bluuebunny/crossref_metadata_2025 huggingface dataset:
Determinants of a social clause in international trade negotiations
Authors: Tavernier Edmund M. , Turvey Calum G.
Published: February 2006

Survey data are used to examine the determinants of a “social clause” in international trade negotiations. Proponents of such a clause argue that the inclusion of labor laws, environmental impacts, and other social issues in international trade negotiations would ensure fair competition, an equitable distribution of the benefits of free trade, and, in the case of labor, protect the basic rights of workers. Opponents see these arguments as a disguised form of protectionism and self‐interest based on the protection of labor‐intensive industries in developed countries. Results from a logit model indicate a decreased likelihood for the inclusion of a social clause in international trade negotiations across farm sizes. In particular the results suggest that agricultural producers with annual gross sales including government payments between US$500,000 and US$999,000, are 40% less likely to want labor laws, environmental impacts, and food safety standards to be included as part of international trade negotiations. The results also show that agricultural producers with college experience or college degrees are less likely to want these social interventions while second generation farmers and first generation farmers with a master's degree want labor laws, environmental impacts, and food safety standards to be included as part of international trade negotiations.
Off‐farm labor supply responses to permanent and transitory farm income
Authors: Kwon Chul‐Woo , Orazem Peter F. , Otto Daniel M.
Published: February 2006

A sample of Iowa farm couples is used to evaluate whether off‐farm labor supply decisions respond to permanent and transitory components of farm income. Off‐farm labor supply of both spouses declines in response to increases in permanent farm income. Farm wives also reduce off‐farm labor supply in response to positive transitory farm income shocks. Consequently, one mechanism farm households use to smooth their goods consumption when facing fluctuating farm income is to modify their consumption of leisure. Ability to smooth goods consumption does not imply the absence of liquidity constraints among farm households unless leisure consumption is also smoothed.
Analysis of a supply‐control program under uncertainty and imperfect competition: Chinese cabbage in Taiwan
Authors: Huang Shu‐Yu , Sexton Richard J. , Xia Tian
Published: February 2006

Researchers have often attributed the farm–wholesale price spread, after adjusting for marketing costs, as compensation for marketing firms' risk bearing. However, price spreads in excess of marketing costs can also be due to marketing firms' exercise of market power. In settings where both imperfect competition and marketer risk aversion are plausible, a modeling framework must be sufficiently general to accommodate both types of behavior. This article develops and estimates such a model in the context of fresh produce marketing and develops the implications for analysis of supply‐control programs. The model is applied to the production and marketing of Chinese cabbage in Taiwan and specifically to the analysis of supply‐control programs implemented in this industry by the Taiwanese government. The empirical results provide little support for the hypothesis that marketing firms exhibit risk averse behavior, but they do show that marketing firms exercise oligopsony power in procurement of the product from farmers, and that this power is positively related to the quantity supplied in each market period. This provides a heretofore unexplored impetus for supply controls intended to raise producer incomes. However, such controls are also rendered less effective by imperfect competition because marketing firms capture part of the benefits from supply reduction.
Price and quantity endogeneity in demand analysis: evidence from directed acyclic graphs
Authors: Wang Zijun , Bessler David A.
Published: February 2006

We propose to use the emerging method of directed graphs to study price/quantity endogeneity issues in empirical demand analysis. The approach is illustrated through the examination of U.S. meat consumption. We find that for two major meat products (beef and poultry), retail prices contemporaneously caused quantities consumed, thus were predetermined. In contrast, the quantity consumed of pork appeared to be predetermined relative to its price.
Modeling winegrape prices in disequilibrium
Authors: Oczkowski Edward
Published: February 2006

This article presents an econometric model of winegrape prices which recognizes the existence of demand and supply imbalances in the Australian market. A “markets in disequilibrium” framework is employed to motivate modeling price changes as responding to variations in excess demand/supply. The disequilibrium price equation provides estimates of regional and varietal price discounts/premiums and a measure of the speed of disequilibrium price adjustment. The equilibrium assumption is rejected for the market and substantial differences between equilibrium and disequilibrium estimates point to the inaccuracies of assuming market clearing. Disequilibrium estimates point to significant differences between warm and cool regions and changing speed of disequilibrium adjustment over time.
Productivity growth and inter‐sector spill‐over in Dutch horticulture, 1976–1995
Authors: Oude Lansink Alfons , Bezlepkin Igor
Published: February 2006

This article calculates nonparametric measures of total factor productivity growth on Dutch horticultural firms in the period 1976–1995. Individual components of total factor productivity growth, i.e., efficiency change and technical change are regressed on socioeconomic factors reflecting the effects of the world oil crises, household and demographic characteristics, location, and investment in physical capital. Also, the article investigates the presence of inter‐sector spill‐overs between groups of firms with different specializations in Dutch horticulture.
Evidence for prescribing exercise as therapy in chronic disease
Authors: Pedersen B. K. , Saltin B.
Published: February 2006

Considerable knowledge has accumulated in recent decades concerning the significance of physical activity in the treatment of a number of diseases, including diseases that do not primarily manifest as disorders of the locomotive apparatus. In this review we present the evidence for prescribing exercise therapy in the treatment of metabolic syndrome‐related disorders (insulin resistance, type 2 diabetes, dyslipidemia, hypertension, obesity), heart and pulmonary diseases (chronic obstructive pulmonary disease, coronary heart disease, chronic heart failure, intermittent claudication), muscle, bone and joint diseases (osteoarthritis, rheumatoid arthritis, osteoporosis, fibromyalgia, chronic fatigue syndrome) and cancer, depression, asthma and type 1 diabetes. For each disease, we review the effect of exercise therapy on disease pathogenesis, on symptoms specific to the diagnosis, on physical fitness or strength and on quality of life. The possible mechanisms of action are briefly examined and the principles for prescribing exercise therapy are discussed, focusing on the type and amount of exercise and possible contraindications.
Ubiquitin Binding in Endocytosis – How Tight Should It Be and Where Does It Happen?
Authors: Madshus Inger Helene
Published: February 2006

Ubiquitin is an important tag in membrane transport. From studies in yeast, monoubiquitin has been considered sufficient to elicit uptake of cell surface transporters and receptors into endosomes. Two articles in the current issue of Traffic (Hawryluk et al. and Barriere et al.) indicate that stronger binding is required to retain and concentrate cargo in endocytic microdomains of the plasma membrane. High avidity interactions can be obtained by tandemly arrayed ubiquitin interaction motifs (UIM), in proteins such as the endocytic adaptors epsin and Eps15, interacting with polyubiquitin or by UIM‐containing proteins binding several ubiquitins brought together through oligomerization of receptors. A controversial issue has been where such interactions take place. One view is that the association of epsin with ubiquitinated cargo is negatively regulated by its interaction with clathrin (Chen H and De Camilli P. Proc Natl Acad Sci USA 2005;102:2766–2771). This contention is now challenged by the articles of Hawryluk et al. and Barriere et al. Hawryluk et al. demonstrate that epsin and Eps15 consistently co‐localize with clathrin but never with caveolin.
Amyloid Precursor Protein and Notch Intracellular Domains are Generated after Transport of their Precursors to the Cell Surface
Authors: Kaether Christoph , Schmitt Stephanie , Willem Michael , Haass Christian
Published: February 2006

Alzheimer's disease is characterized by brain deposition of extracellular amyloid β‐peptide (Aβ)‐containing plaques. The cellular site of γ‐secretase activity, which releases Aβ and the corresponding amyloid precursor protein intracellular domain (AICD), remains controversial. Proposed cleavage sites range from the endoplasmic reticulum (ER), the Golgi apparatus, and the cell surface to endosomal compartments. We now used C99‐green fluorescent protein (GFP), a fluorescent reporter substrate for γ‐secretase activity and monitored AICD production in living cells. C99‐GFP is efficiently cleaved by γ‐secretase, and AICD‐GFP is released into the cytosol. Inhibiting γ‐secretase results in accumulation of C99‐GFP in early endosomes. By blocking selective transport steps along the secretory pathway, we demonstrate that γ‐secretase does not cleave its substrates in the ER, the Golgi/trans‐Golgi network, or in secretory vesicles. In contrast, inhibition of endocytosis did not inhibit cleavage of C99‐GFP. Similar results were obtained for another γ‐secretase substrate, NotchΔE. Our results suggest that intracellular domains are generated by γ‐secretase at the plasma membrane and/or early endosomes.
Autoantibodies in Argentine Women with Recurrent Pregnancy Loss
Authors: Bustos Daniel , Moret Ana , Tambutti Monica , Gogorza Sebastian , Testa Roberto , Ascione Amanda , Prigoshin Norma
Published: February 2006

Problem

To determine the presence or absence of subclinical autoimmunity in Caucasian Argentine healthy women with first trimester recurrent pregnancy loss (RPL), the sera of 118 healthy women with a history of three or more consecutive abortions and 125 fertile control women without abortions and two children were analyzed for the presence of autoantibodies: immunoglobulin (Ig)G and IgM anticardiolipin, antinuclear (ANA), antismooth muscle (ASMA), antimitocondrial (AMA), antiliver‐kidney‐microsomal fraction (LKM), antigastric parietal cells (GPC), antineutrophil cytoplasmatic (ANCA) and antibodies antigliadin type IgA and IgG and IgA antitransglutaminase related with celiac disease (CD).

Method of study

ANA, ASMA, AMA, anti‐LKM, antibodies to GPC and ANCA were determined by indirect immunofluorescence (IFI) and anticardiolipin, antigliadina and antitransglutaminase antibodies were measured by enzyme‐linked immunosorbent assays (ELISA).

Results

There was no significant difference between controls and patients with ANA, ASMA, AMA, LKM, ANCA and GPC. The prevalence of anticardiolipin antibodies in RPL was significantly higher than controls (P < 0,01) and the prevalence of positive antibodies for antigliadina type IgA and IgG and IgA antitransglutaminase in RPL was significantly higher than controls (P < 0.04).

Conclusion

We show that Caucasian Argentine women with RPL showed significantly higher incidence of anticardiolipin antibodies than normal controls and finally we recommended the screening of IgA and IgG antigliadina and IgA antitransglutaminase antibodies in pregnancy, because of the high prevalence of subclinical CD in RPL and the chance of reversibility through consumption of a gluten free diet.
A Sandwich Enzyme‐Linked Immunoabsorbent Assay for Measurement of Gonadotropin‐Releasing Hormone‐Toxin Conjugates
Authors: Yang Wei‐Hsiung , Allen Matt C. , Wieczorek Maciej , Michael Glode L. , Nett Terry M.
Published: February 2006

Problem  Biological effectiveness of targeted cytotoxins is dependent on their stability, circulating half‐life, receptor binding ability, and cytotoxicity. The objective of this study was to compare stability of gonadotropin‐releasing hormone (GnRH)‐toxin conjugates made with disulfide linkers to those using a maleimidodibutyryl (mb) linkage.

Method of study  We developed a sandwich enzyme‐linked immunoabsorbent assay recognizing both GnRH analog and cytotoxin to ensure the conjugate measured was intact. Anti‐D‐Leu6‐GnRH was used for capture and anti‐pokeweed antiviral protein (anti‐PAP) or anti‐RNase for quantification. Specificity was verified by lack of reactivity with ovine FSH and LH, PAP, RNase, and D‐Lys6‐GnRH.

Results  Conjugates prepared using disulfide linkages were not stable in serum in vitro (half‐lives <10 min), whereas mb conjugates had half‐lives >2 hr. Clearance of mbGnRH‐PAP from the circulation of sheep was rapid (t1/2 <20 min).

Conclusion  The assays were found to be specific, sensitive and accurate for measurement of GnRH‐toxin conjugates in vitro and in vivo.
Short‐term Cytolytic Mediators’ Expression in Decidual Lymphocytes is Enhanced by Interleukin‐15
Authors: Strbo Natasa , Laskarin Gordana , Crncic Tatjana Bogovic , Juretic Frankovic Koraljka , Bedenicki Ivica , Tokmadzic Vlatka Sotosek , Randic Ljiljana , Bouteiller Philippe Le , Tabiasco Julie , Podack Eckhard R. , Rukavina Daniel
Published: February 2006

Problem

We investigated whether decidual adherent cells (DAC) and interleukin (IL)‐15, in comparison to interleukin (IL)‐2 affect cytolytic potential of first trimester decidual lymphocytes (DL).

Method of study

Decidual mononuclear cells were obtained by enzymatic digestion and density gradient centrifugation. Non‐adherent DL were collected after 2‐hr adherence and cultured for 18 or 72 hr with: IL‐15 (0.5–5 ng/mL), IL‐2 (100–1000 U/mL) or both of these cytokines, DAC (ratio 3:1 and 1:1) or DAC and anti‐IL‐15 antibody. Perforin, Fas ligand (FasL) and granzyme B were detected at mRNA level in indicated culture conditions. Cytolytic activity of DL against K‐562, P815 and P815‐Fas was measured by 2‐hr PKH‐26 cytotoxicity assay. The dynamics of perforin protein and mRNA expression were measured in DL after a contact with K‐562 targets.

Results

Interleukin‐15 enhanced perforin, FasL and granzyme B transcription after 18‐hr culture and prevented perforin protein downregulation, observed after DL culture. IL‐2 had similar effects. DAC sustained perforin expression in DL and anti‐IL‐15 monoclonal antibody abrogated this effect. DAC increased cytotoxicity of DL against K‐562 which was mediated by IL‐15.

Conclusion

Interleukin‐15, probably produced by DAC, upregulates cytolytic mediators’ expression and perforin‐mediated cytotoxicity of DL, with equal efficiency as high concentrations of IL‐2.
Elevation of Macrophage Colony‐Stimulating Factor in Amniotic Fluid at Late Stage of Normal Pregnancy
Authors: Hayashi Masatoshi , Hombo Yoshiyasu , Shibazaki Mitsuei , Nakajima Atsuko , Inaba Noriyuki
Published: February 2006

Problem

Macrophage colony‐stimulating factor (M‐CSF) promotes placental growth and maintenance, and regulates trophoblast invasion into the placental bed. We evaluated whether the amniotic fluid M‐CSF levels at the late stage of normal pregnancy is altered compared with those at the middle stage.

Method of study

This study enrolled 52 subjects experiencing normotensive pregnancies with single fetuses, of whom 26 were women at the late stage (term gravidas) and 26 were women at the middle stage (controls). The average gestational age at entry was 38 weeks of gestation and 17 weeks, respectively. Amniotic fluid was collected from these subjects. Amniotic fluid M‐CSF levels were determined by the enzyme‐linked immunosorbent assay method then compared between term gravidas and controls.

Results

Amniotic fluid M‐CSF concentrations were 4815 pg/mL (median) in term gravidas and 3795 pg/mL in controls; the concentrations were significantly higher in term gravidas than in controls.

Conclusions

We demonstrated a significant increase in amniotic fluid M‐CSF levels in term gravidas. These results suggest that elevated levels of M‐CSF in amniotic fluid have an important immunological function in the maintenance of pregnancy and fetal growth.
Embryonic Stem Cells: Similarities and Differences Between Human and Murine Embryonic Stem Cells
Authors: Koestenbauer Sonja , Zech Nicolas H. , Juch Herbert , Vanderzwalmen Pierre , Schoonjans Luc , Dohr Gottfried
Published: February 2006

The derivation of murine embryonic stem (mES) cell lines was reported for the first time in 1981 (Nature, 1981; 292:154–156; Proc Natl Acad Sci U S A, 1981; 78:7634–7638), and they have since proved to be a very useful tool with which to study mammalian development, which is characterized by pluripotency and differentiation. About 20 years later, the successful generation of human embryonic stem (hES) cell lines was described (Science, 1998; 282:1145–1147). Although mES and hES are derived from mammals, they cannot be looked at as being one and the same. While basic information for hES can be derived from mES, such information does not correspond on a one‐to‐one basis. This review gives an overview of the characteristics of embryonic stem cells with the main focus on the similarities and differences between human and mES cells.
High Levels of Peripheral Blood NK Cells in Women Suffering from Recurrent Spontaneous Abortion are Reverted from High‐Dose Intravenous Immunoglobulins
Authors: Perricone Roberto , Muzio Gioia Di , Perricone Carlo , Giacomelli Roberto , Nardo Domenico De , Fontana Luigi , Carolis Caterina De
Published: February 2006

Problem

To determine the levels of peripheral blood natural killer (NK) cells in healthy women and recurrent aborters, and the effect of intravenous immunoglobulins (IVIGs) on these levels.

Method of study

A total of 659 women were evaluated for NK cells by means of flow cytofluorimetry: 42 non‐pregnant healthy women, 394 non‐pregnant recurrent spontaneous abortion (RSA) women, 36 pregnant healthy women and 187 pregnant RSA women. Fifty‐four of the pregnant RSA women were treated with IVIG; in 18 of them NK cells were measured immediately before and after the very first IVIG infusion (0.5 g/kg body weight).

Results

Blood NK cell results were increased in RSA pregnant/non‐pregnant women, and significantly reduced by IVIG, even after the very first infusion. In RSA pregnant women treated by means of IVIG therapy, 92.3% success rate was observed.

Conclusions

High levels of NK cells are detected in women affected by RSA. IVIGs are capable of decreasing them with a short‐ and long‐term efficacy, allowing having a very high success rate of pregnancies in RSA women.
Evidence for Expression of Both Classical and Non‐Classical Major Histocompatibility Complex Class I Genes in Bovine Trophoblast Cells
Authors: Davies Christopher J. , Eldridge Jennifer A. , Fisher Patricia J. , Schlafer Donald H.
Published: February 2006

Problem

During the third trimester of pregnancy bovine trophoblast cells in the interplacentomal and arcade regions of the placenta express major histocompatibility complex class I (MHC‐I) antigens. At parturition immunological recognition of MHC‐I antigens appears to contribute to normal placental release. Therefore, we hypothesized that during late pregnancy bovine trophoblast cells express polymorphic, classical MHC‐I antigens.

Method of study

Cloning, microarray screening and sequencing of cDNA were used to study transcription of MHC‐I genes in peripheral blood mononuclear cells (PBMC) and interplacentomal, trophoblast cells. Real‐time reverse transcription, polymerase chain reaction (RT‐PCR) was used to compare the abundance of MHC‐I transcripts in PBMC and trophoblast cells.

Results

Screening of cloned MHC‐I cDNA on MHC‐I microarrays indicated that in PBMC 90–98% of MHC‐I transcripts were encoded by classical MHC‐I genes with the remainder encoded by non‐classical MHC‐I genes. In contrast, 21–66% of MHC‐I transcripts from interplacentomal trophoblast cells were from classical genes and 34–79% were from non‐classical genes. Transcripts from four non‐classical MHC‐I loci were identified by sequence analysis. Real‐time RT‐PCR indicated that the overall levels of MHC‐I gene expression in PBMC and trophoblast were similar.

Conclusion

Bovine interplacentomal trophoblast cells express both classical and non‐classical MHC‐I genes, but the relative level of expression varies considerably.
The Impact of Merger Activity on Executive Pay in the United Kingdom
Authors: GIRMA SOURAFEL , THOMPSON STEVE , WRIGHT PETER W.
Published: February 2006

We examine the impact of mergers and acquisitions on the remuneration of CEOs in the UK from 1981 to 1996. We find that CEO pay is not strongly related to company performance. In contrast, increases in firm size do have a significant impact. There is also evidence that acquisitions offer CEOs the scope to influence their pay positively. We also note however that CEOs engaging in ‘wealth‐reducing’ acquisitions experience significantly lower remuneration than their counterparts whose deals meet with market approval. This result suggests that shareholder–principals have at least some success in penalizing managers for unwarranted, empire‐building, mergers.
Dumping: Trade Policy in Need of a Theoretical Make Over*
Authors: Kerr William A.
Published: February 2006

But sufficient justification is to be found in the usage of the most authoritative writers and in the considerations of economy and precision of terminology for confining the term dumping toprice‐discrimination between national markets(original emphasis).

Jacob Viner (1923, p. 3)1

Anti‐dumping cases are on the rise internationally and are becoming a major weapon in the protectionist arsenal. The definitions of dumping, however, are not based on theoretically sound economic reasoning meaning firms are often falsely accused of engaging in unfair pricing practices when exporting. The historic bases of the current definitions are outlined and their theoretical deficiencies fully explained. Suggestions are made regarding how the definition of dumping used in international law could be put on a sound economic basis.

Les cas d'antidumping sont internationalement à la hausse et deviennent une arme importante dans l'arsenal du protectionniste.Cependant, les définitions de dumping ne sont pas basées sur un raisonnement économique théoriquement sains, c'est à dire les firmes exportatrices sont souvent faussement accusées de s'engager dans des pratiques de tarification favorables. Les bases historiques des définitions courantes sont décrites et leurs insuffisances théoriques sont entièrement expliquées. Des suggestions sont faites concernant la façon dont la définition de dumping dans le droit international pourrait être basée sur des concepts économiques solides.
Tariff‐Rate Quota Liberalization: The Case of World Price Uncertainty and Supply Management
Authors: Rude James I. , Gervais Jean‐Philippe
Published: February 2006

This paper examines the options for liberalizing tariff‐rate quotas when a marketing board controls domestic production and international prices are stochastic. Lowering over‐quota tariff and increasing import quota volumes are not equivalent. The trade‐offs between the two types of trade reforms are examined through numerical simulations for the Canadian chicken industry. Introducing world price variability results in a distribution of welfare impacts for the different groups in the industry. Consumers and processors gain more with tariff liberalization than with increased import quotas. The difference in producer surplus between liberalization regimes is truncated so that producers only see down‐side risk under the tariff liberalization regime.

Le présent article a examiné les options concernant la libéralisation des contingents tarifaires lorsqu'un office de commercialisation encadre la production nationale et que les prix internationaux sont stochastiques. Diminuer le taux de droit hors contingent et augmenter les volumes de contingent d'importation ne sont pas des options équivalentes. Nous avons examiné les deux types de réforme commerciale en effectuant des simulations numériques pour le secteur du poulet au Canada. Incorporer la variabilité du prix mondial provoque une distribution de répercussions sur le bien‐être des divers groupes du secteur. Les consommateurs et les transformateurs gagnent davantage en appliquant une libéralisation des droits hors contingent qu'en appliquant une augmentation des contingents d'importation. La différence quant au surplus des producteurs entre les régimes de libéralisation est tronquée de sorte que les producteurs ne voient que le risque de perte sous un régime de libéralisation tarifaire.
Estimating the Impacts of Government Interventions in the International Rice Market
Authors: Chen Chi‐Chung , McCarl Bruce A. , Chang Ching‐Cheng
Published: February 2006

A procedure is developed to estimate the distortions and welfare impacts of government interventions in the international rice market. The procedure is based on a spatial equilibrium model and the application of conjectural variations. The model estimates asymmetric price distortions caused by policies in both exporting and importing countries. We find that the measures of price distortion are slightly larger due to actions in importing countries than in exporting countries. The results show that welfare gains of U.S.$1.2 billion or about 14.8% are possible when all trading distortions are removed.

Nous avons mis au point une méthode pour estimer les répercussions de l'intervention gouvernementale sur les distorsions et le bien‐être sur le marché international du riz. Cette méthode est fondée sur un modèle d'équilibre spatial et l'application de variations conjecturales. Le modèle estime les distorsions de prix asymétriques causées par les politiques des pays exportateurs et importateurs. Nous avons trouvé que la distorsion des prix est légèrement plus élevée dans les pays importateurs que dans les pays exportateurs, en raison de leurs mesures respectives. Les résultats ont montré qu'il était possible de réaliser des gains de 1,2 milliard $US, soit environ 14.8 %, en éliminant la distorsions des échanges.
Insuring Eggs in Baskets: Should the Government Insure Individual Risks?
Authors: Hart Chad E. , Hayes Dermot J. , Babcock Bruce A.
Published: February 2006

The vast majority of crop and revenue insurance policies sold in North America are single‐crop policies that insure against low yields or low revenues for each crop grown on a particular farm. This practice of insuring one crop at a time runs counter to the traditional risk management practice of diversifying across several enterprises to avoid putting all of one's eggs in a single basket. This paper examines the construction of a whole‐farm crop revenue insurance program to include livestock price risk. The results show that at coverage levels of 95% or lower, the fair insurance premiums for this product on a well‐diversified Iowa farm are far lower than the fair premiums for the corn crop alone on the same farm. The calculation of premium rates for the whole‐farm insurance product is derived from a method for imposing correlations first proposed by Iman and Conover in 1982. The potential income transfer from crop insurance is also examined. We find that the income transfer due to the subsidization of single‐commodity policies is greater than the total premium for whole‐farm policies.

La grande majorité de polices d'assurances de récolte et de revenu agricole vendues en Amérique du nord sont des polices de récolte individuelle qui assurent contre des rendements faibles ou bas revenu pour chaque récolte cultivée par une ferme particulière. Cette pratique de n'assurer une récolte à la fois fonctionne à l'opposé de la pratique traditionnelle de gestion des risques par la diversification à travers plusieurs entreprises pour éviter de mettre tous ses oeufs dans un seul panier. Cet article examine la construction d'un programme d'assurance agricole pour l'ensemble des récoltes produites par une ferme y compris le bétail évalue le risque. Les résultats montrent qu'aux niveaux d'assurance plus petits ou égaux à 95 pourcents, les primes d'assurance justes pour ce type de police pour une ferme bien diversifiée de l'Iowa sont bien inférieures aux primes justes pour une police de simple couvrant le maïs et ce pour la même ferme. Le calcul des taux de prime pour une police couvrant l'ensemble des récoltes est dérivé d'une méthode pour imposer des corrélations originalement proposée par Iman et Conover en 1982. Le transfert potentiel de revenu à partir de l'assurance de récolte agricole est également examiné. Nous trouvons que le transfert de revenu dûà la subvention des polices pour récolte singulière est plus grand que la prime entière pour une police couvrant l'ensemble des récoltes.
Verifying Timing and Frequency of Revealed Preference Violations and Application to the BSE Outbreak in Japan
Authors: Jin Hyun J.
Published: February 2006

This paper proposes a method to differentiate a socioeconomic shock from other transitory shocks in the revealed preference test by verifying the timing and frequency of the demand shifts. If frequency of the revealed preference violations is substantially high in a period that is synchronized with the timing of a socioeconomic shock, it suggests that changes in the demand patterns are because of the socioeconomic shock. Specifically, this paper splits the entire sample into several subperiods and compares the expected probability and realized probability of noting observations involved in the shifts. The method is applied to the Japanese and South Korean meat import demand related to the bovine spongiform encephalopathy (BSE) outbreak in Japan. Empirical results show that there are excess violations after September 2001 in the Japanese data but not in the South Korean data, suggesting that the BSE event has influenced Japanese meat import demand, but not South Korean meat import demand.

Le présent article propose une méthode pour distinguer un choc socioéconomique d'autres formes de chocs transitoires dans le test des préférences révélées en vérifiant le moment et la fréquence des déplacements de la demande. Si la fréquence des violations de préférences révélées est substantiellement élevée au cours d'une période correspondant à la survenue d'un choc socioéconomique, les changements observés dans les courbes de demande pourraient être liés au choc socioéconomique. Plus particulièrement, nous avons divisé l'échantillon en plusieurs sous‐périodes et avons comparé la probabilité anticipée et la probabilité réalisée d'après les observations notées dans les déplacements. Nous avons appliqué cette méthode à la demande d'importation de viande du Japon et de la Corée du Sud à la suite de la flambée d'ESB au Japon. Les résultats empiriques ont montré de nombreuses violations après septembre 2001 dans les données japonaises, mais non dans les données sud‐coréennes, ce qui porte à croire que l'épisode d'ESB a influencé la demande d'importation de viande du Japon, mais non celle de la Corée du Sud.
The Siting of Livestock Facilities and Environmental Regulations
Authors: Weersink Alfons , Eveland Christin
Published: February 2006

The significant variation in the stringency of environmental regulations across Ontario municipalities in the late 1990s created the possibility of pollution havens where expanding livestock operations would locate in those municipalities with the lowest regulatory compliance costs. Using actual building permit data rather than aggregate regional production numbers, the study examined the factors affecting spatial changes. Instead of locating to reduce environmental compliance costs as suggested by the pollution haven hypothesis, barns are being built largely where the livestock sector is concentrated suggesting the existence of agglomeration economies. The result suggests that the normalization of standards across the province through the new Nutrient Management Act will not significantly influence the location decisions of expanding or new livestock facilities which are largely determined by economic factors associated with livestock infrastructure support.

L'importante variation de sévérité des règlements environnementaux dans les municipalités de l'Ontario vers la fin des années 1990 a créé la possibilité de refuges pour pollueurs: les fermes d'élevage en expansion allaient s'installer dans les municipalités où les coûts de conformité aux règlements étaient les plus faibles. À l'aide de données sur les permis de construire plutôt que de données agrégées sur la production régionale, la présente étude a examiné les facteurs qui influaient sur les changements spatiaux. Au lieu de s'installer là où les coûts de conformité aux règlements sont faibles comme le laisse supposer l'hypothèse des refuges pour pollueurs, les entreprises choisissent de s'installer là où le secteur de l'élevage est concentré, ce qui laisse supposer l'existence d'économies d'agglomération. Les résultats semblent indiquer que l'uniformisation des normes à l'échelle provinciale en vertu de la Loi sur la gestion des éléments nutritifs n'aura pas d'influence significative sur le choix des endroits où seront construits les bâtiments des exploitations en expansion ou des nouvelles exploitations puisque ce choix est en grande partie motivé par des facteurs économiques liés au soutien à l'infrastructure de l'élevage.
Myofascial force transmission is increasingly important at lower forces: firing frequency‐related length–force characteristics of rat extensor digitorum longus
Authors: Meijer H. J. M. , Baan G. C. , Huijing P. A.
Published: February 2006

Aim:  Effects of submaximal stimulation frequencies on myofascial force transmission were investigated for rat anterior crural muscles with all motor units activated.

Methods:  Tibialis anterior and extensor hallucis longus (TAEHL) muscles were kept at constant muscle–tendon complex length, but extensor digitorum longus muscle (EDL) was lengthened distally. All muscles were activated simultaneously at 10, 20, 30 and 100 Hz within an intact anterior crural compartment.

Results:  At lower frequencies, significant proximo‐distal EDL force differences exist. Absolute EDL proximo‐distal active force differences were highest at 100 Hz (ΔFdist‐prox = 0.4 N). However, the normalized difference was highest at 10 Hz (ΔFdist‐prox = 30%Fdist). Firing‐frequency dependent shifts of the ascending limb of the EDL length–force curve to higher lengths were confirmed for a muscle within an intact compartment, although effects of firing frequency assessed at proximal and distal EDL tendons differed quantitatively. As EDL was lengthened distally, TAEHL distal isometric active force decreased progressively. The absolute decrease was highest for 100 Hz (ΔFfrom initial = −0.25 N). However, the highest normalized decrease was found for 10 Hz stimulation (ΔFfrom initial = −40%).

Conclusions:  At submaximal stimulation frequencies, myofascial force transmission is present and the fraction of force transmitted myofascially increases with progressively lower firing frequencies. Evidently, the stiffness of epimuscular myofascial paths of force transmission decreases less than the stiffness of serial sarcomeres and myotendinous pathways. It is concluded that low firing frequencies as encountered in vivo enhance the relative importance of epimuscular myofascial force transmission with respect to myotendinous force transmission.
The Global Regulatory Proteins LetA and RpoS Control Phospholipase A, Lysophospholipase A, Acyltransferase, and Other Hydrolytic Activities of
Legionella pneumophila
JR32
Authors: Broich Markus , Rydzewski Kerstin , McNealy Tamara L. , Marre Reinhard , Flieger Antje
Published: February 2006

Legionella pneumophila
possesses a variety of secreted and cell-associated hydrolytic activities that could be involved in pathogenesis. The activities include phospholipase A, lysophospholipase A, glycerophospholipid:cholesterol acyltransferase, lipase, protease, phosphatase, RNase, and
p
-nitrophenylphosphorylcholine (p-NPPC) hydrolase. Up to now, there have been no data available on the regulation of the enzymes in
L. pneumophila
and no data at all concerning the regulation of bacterial phospholipases A. Therefore, we used
L. pneumophila
mutants in the genes coding for the global regulatory proteins RpoS and LetA to investigate the dependency of hydrolytic activities on a global regulatory network proposed to control important virulence traits in
L. pneumophila
. Our results show that both
L. pneumophila rpoS
and
letA
mutants exhibit on the one hand a dramatic reduction of secreted phospholipase A and glycerophospholipid:cholesterol acyltransferase activities, while on the other hand secreted lysophospholipase A and lipase activities were significantly increased during late logarithmic growth phase. The cell-associated phospholipase A, lysophospholipase A, and p-NPPC hydrolase activities, as well as the secreted protease, phosphatase, and p-NPPC hydrolase activities were significantly decreased in both of the mutant strains. Only cell-associated phosphatase activity was slightly increased. In contrast, RNase activity was not affected. The expression of
plaC
, coding for a secreted acyltransferase, phospholipase A, and lysophospholipase A, was found to be regulated by LetA and RpoS. In conclusion, our results show that RpoS and LetA affect phospholipase A, lysophospholipase A, acyltransferase, and other hydrolytic activities of
L. pneumophila
in a similar way, thereby corroborating the existence of the LetA/RpoS regulation cascade.
Oxygen Reactivity of PutA from
Helicobacter
Species and Proline-Linked Oxidative Stress
Authors: Krishnan Navasona , Becker Donald F.
Published: February 2006

Proline is converted to glutamate in two successive steps by the proline utilization A (PutA) flavoenzyme in gram-negative bacteria. PutA contains a proline dehydrogenase domain that catalyzes the flavin adenine dinucleotide (FAD)-dependent oxidation of proline to Δ
1
-pyrroline-5-carboxylate (P5C) and a P5C dehydrogenase domain that catalyzes the NAD
+
-dependent oxidation of P5C to glutamate. Here, we characterize PutA from
Helicobacter hepaticus
(PutA
Hh
) and
Helicobacter pylori
(PutA
Hp
) to provide new insights into proline metabolism in these gastrointestinal pathogens. Both PutA
Hh
and PutA
Hp
lack DNA binding activity, in contrast to PutA from
Escherichia coli
(PutA
Ec
), which both regulates and catalyzes proline utilization. PutA
Hh
and PutA
Hp
display catalytic activities similar to that of PutA
Ec
but have higher oxygen reactivity. PutA
Hh
and PutA
Hp
exhibit 100-fold-higher turnover numbers (∼30 min
−1
) than PutA
Ec
(<0. 3 min
−1
) using oxygen as an electron acceptor during catalytic turnover with proline. Consistent with increased oxygen reactivity, PutA
Hh
forms a reversible FAD-sulfite adduct. The significance of increased oxygen reactivity in PutA
Hh
and PutA
Hp
was probed by oxidative stress studies in
E. coli.
Expression of PutA
Ec
and PutA from
Bradyrhizobium japonicum
, which exhibit low oxygen reactivity, does not diminish stress survival rates of
E. coli
cell cultures. In contrast, PutA
Hp
and PutA
Hh
expression dramatically reduces
E. coli
cell survival and is correlated with relatively lower proline levels and increased hydrogen peroxide formation. The discovery of reduced oxygen species formation by PutA suggests that proline catabolism may influence redox homeostasis in the ecological niches of these
Helicobacter
species.
Biosynthesis of a Natural Polyketide-Isoprenoid Hybrid Compound, Furaquinocin A: Identification and Heterologous Expression of the Gene Cluster
Authors: Kawasaki Takashi , Hayashi Yutaka , Kuzuyama Tomohisa , Furihata Kazuo , Itoh Nobuya , Seto Haruo , Dairi Tohru
Published: February 2006

Furaquinocin (FQ) A, produced by
Streptomyces
sp. strain KO-3988, is a natural polyketide-isoprenoid hybrid compound that exhibits a potent antitumor activity. As a first step toward understanding the biosynthetic machinery of this unique and pharmaceutically useful compound, we have cloned an FQ A biosynthetic gene cluster by taking advantage of the fact that an isoprenoid biosynthetic gene cluster generally exists in flanking regions of the mevalonate (MV) pathway gene cluster in actinomycetes. Interestingly,
Streptomyces
sp. strain KO-3988 was the first example of a microorganism equipped with two distinct mevalonate pathway gene clusters. We were able to localize a 25-kb DNA region that harbored FQ A biosynthetic genes (
fur
genes) in both the upstream and downstream regions of one of the MV pathway gene clusters (MV2) by using heterologous expression in
Streptomyces lividans
TK23. This was the first example of a gene cluster responsible for the biosynthesis of a polyketide-isoprenoid hybrid compound. We have also confirmed that four genes responsible for viguiepinol [3-hydroxypimara-9(11),15-diene] biosynthesis exist in the upstream region of the other MV pathway gene cluster (MV1), which had previously been cloned from strain KO-3988. This was the first example of prokaryotic enzymes with these biosynthetic functions. By phylogenetic analysis, these two MV pathway clusters were identified as probably being independently distributed in strain KO-3988 (orthologs), rather than one cluster being generated by the duplication of the other cluster (paralogs).
Nickel Represses the Synthesis of the Nickel Permease NixA ofHelicobacter pylori
Authors: Wolfram Lutz , Haas Elvira , Bauerfeind Peter
Published: February 2006

Nickel acquisition is necessary for urease activity, a major virulence factor of the human gastric pathogenHelicobacter pylori. NixA was identified as a specific nickel uptake system in this organism. Addition of small amounts of nickel to media strongly stimulates urea hydrolysis. On the other hand, high nickel concentrations are deleterious to cell growth. As a possible protective reaction, nickel uptake seems to be reduced inH. pylorigrown in nickel-rich media. These observations led to investigations of regulation of the expression of the nickel permease NixA. We found that increasing the nickel concentration in media reduced the amount of NixA. In order to address the question of whether this phenomenon was subject to transcriptional or translational regulation, we quantifiednixAmRNA fromH. pyloriby real-time PCR. The amount ofnixAmRNA was gradually reduced five- to sevenfold in a time- and concentration-dependent manner. Repression could be measured as soon as 5 min after nickel addition, and the maximum repression occurred after 20 to 30 min. The maximum repression was obtained with an external nickel concentration of 100 μM. The observed nickel repression of NixA was dependent onnikRencoding the nickel-responsive regulatory protein NikR. In conclusion, we demonstrated that synthesis of the NixA nickel permease ofH. pylorishows nickel-responsive regulation mediated by NikR to maintain the balance between effective nickel acquisition and a toxic overload.
Archaeal and Bacterial SecD and SecF Homologs Exhibit Striking Structural and Functional Conservation
Authors: Hand Nicholas J. , Klein Reinhard , Laskewitz Anke , Pohlschröder Mechthild
Published: February 2006

The majority of secretory proteins are translocated into and across hydrophobic membranes via the universally conserved Sec pore. Accessory proteins, including the SecDF-YajC
Escherichia coli
membrane complex, are required for efficient protein secretion.
E. coli
SecDF-YajC has been proposed to be involved in the membrane cycling of SecA, the cytoplasmic bacterial translocation ATPase, and in the stabilizing of SecG, a subunit of the Sec pore. While there are no identified archaeal homologs of either SecA or SecG, many archaea possess homologs of SecD and SecF. Here, we present the first study that addresses the function of archaeal SecD and SecF homologs. We show that the SecD and SecF components in the model archaeon
Haloferax volcanii
form a cytoplasmic membrane complex in the native host. Furthermore, as in
E. coli
, an
H. volcanii
Δ
secFD
mutant strain exhibits both severe cold sensitivity and a Sec-specific protein translocation defect. Taken together, these results demonstrate significant functional conservation among the prokaryotic SecD and SecF homologs despite the distinct composition of their translocation machineries.
CcpA Causes Repression of the
phoPR
Promoter through a Novel Transcription Start Site, P
A6
Authors: Puri-Taneja Ankita , Paul Salbi , Chen Yinghua , Hulett F. Marion
Published: February 2006

The
Bacillus subtilis
PhoPR two-component system is directly responsible for activation or repression of Pho regulon genes in response to phosphate deprivation. The response regulator, PhoP, and the histidine kinase, PhoR, are encoded in a single operon with a complex promoter region that contains five known transcription start sites, which respond to at least two regulatory proteins. We report here the identification of another direct regulator of
phoPR
transcription, carbon catabolite protein A, CcpA. This regulator functions in the presence of glucose or other readily metabolized carbon sources. The maximum derepression of
phoPR
expression in a
ccpA
mutant compared to a wild-type stain was observed under excess phosphate conditions with glucose either throughout growth in a high-phosphate defined medium or in a low-phosphate defined medium during exponential growth, a growth condition when
phoPR
transcription is low in a wild-type strain due to the absence of autoinduction. Either HPr or Crh were sufficient to cause CcpA dependent repression of the
phoPR
promoter in vivo. A
ptsH1
(Hpr)
crh
double mutant completely relieves
phoPR
repression during phosphate starvation but not during phosphate replete growth. In vivo and in vitro studies showed that CcpA repressed
phoPR
transcription by binding directly to the
cre
consensus sequence present in the promoter. Primer extension and in vitro transcription studies revealed that the CcpA regulation of
phoPR
transcription was due to repression of P
A6
, a previously unidentified promoter positioned immediately upstream of the
cre
box. Eσ
A
was sufficient for transcription of P
A6
, which was repressed by CcpA in vitro. These studies showed direct repression by CcpA of a newly discovered Eσ
A
-responsive
phoPR
promoter that required either Hpr or Crh in vivo for direct binding to the putative consensus
cre
sequence located between P
A6
and the five downstream promoters characterized previously.