bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Programming and Learning Models for Management of a Nonnative Species
Authors: Eiswerth Mark E. , Van Kooten G. Cornelis 
Published: October 2007

Nonnative invasive species result in sizeable economic damages and control costs. Because dynamic optimization models break down if controls depend in complex ways on past controls, nonuniform or scale‐dependent spatial attributes, etc., decision‐support systems that allow learning may be preferred. We compare two models of an invasive weed in California's grazing lands: (i) a stochastic dynamic programming model and (ii) a reinforcement‐based, experience‐weighted attraction (EWA) learning model. We extend the EWA approach by including stochastic forage growth and penalties for repeated application of environmentally harmful controls. Results indicate that EWA learning models offer some promise for managing invasive species. Les espèces non indigènes envahissantes entraînent des dommages économiques et des coûts de lutte considérables. Compte tenu que les modèles d'optimisation dynamique échouent lorsque les moyens de lutte dépendent, de façon complexe, de moyens de lutte antérieurs, d'attributs spatiaux influencés par l'échelle ou non uniformes, etc., l'utilisation de systèmes d'aide à la décision permettant l'apprentissage pourrait être préférable. Nous avons comparé deux modèles dans le cas d'une plante adventice envahissant les pâturages de la Californie: 1. un modèle de programmation dynamique stochastique; 2. un modèle d'apprentissage experience‐weighted attraction (EWA), fondé sur le renforcement. Nous avons élargi le modèle EWA en y incluant la croissance stochastique des fourrages et des pénalités imposées pour l'utilisation répétée de moyens de lutte dommageables pour l'environnement. Selon les résultats obtenus, les modèles d'apprentissage EWA semblent prometteurs pour la gestion des espèces envahissantes.
Economic Effects of Mitigating Apple Maggot Spread
Authors: Zhao Zishun , Wahl Thomas , Marsh Thomas 
Published: October 2007

Apple maggot is an economically important apple pest that is native to the East Coast of North America, including Canada and the United States. Introduced to the West Coast of the United States in 1979, the pest is spreading rapidly in the region, threatening the major apple production area of Washington State, as well as British Columbia. A dynamic simulation model for perennial fruit production is developed to study the potential economic impact of a pest species, such as apple maggot. The model is designed to provide essential information, including the intertemporal distribution of welfare, to aid the design of effective and efficient policy response to pest outbreaks. This model is used to simulate the economic impact of apple maggot spread in Washington State on apple price, trade flows, and welfare changes. La mouche de la pomme est un ravageur originaire de la côte Est de l'Amérique du Nord (canadienne et étatsunienne) qui cause des pertes économiques considérables. Ce ravageur, qui s'est introduit sur la côte Ouest des États‐Unis en 1979, se propage rapidement et menace les principales zones de production de pomme de l'État de Washington et de la Colombie‐Britannique. Nous avons élaboré un modèle de simulation dynamique pour la production pluriannuelle de fruits afin d'étudier l'incidence économique potentielle d'espèces ravageuses telles que la mouche de la pomme. Le modèle a été conçu pour fournir de l'information essentielle, dont la distribution du bien‐être intertemporel, en vue de contribuer à l'élaboration d'une réaction politique efficace de lutte contre les pullulations de ravageurs. Ce modèle est utilisé pour simuler l'incidence économique de la propagation de la mouche de la pomme dans l'État de Washington sur le prix des pommes, le flux des échanges commerciaux et les changements touchant le bien‐être.
PVYn and Potato Wart Disease Outbreaks in Prince Edward Island: Policy Response and Analysis
Authors: Clark J. Stephen , Prochazka Petr , Yiridoe Emmanuel K. , Prochazkova Katerina 
Published: October 2007

This study analyzed the impact of PVYn and potato wart disease outbreaks in PEI on the potato industry. The two disease outbreaks resulted in loss of the U.S. seed export market to PEI producers. The effects of the disease outbreaks were mitigated through value‐added processing. Price premiums for processed potatoes allowed PEI potato farmers to abandon seed export and helped to sustain financial viability potato production. Policy responses to the two disease outbreaks include (i) development of zones policies, which helped to reopen markets into the United States, and (ii) compensation to producers above the minimum levels required under the federal Seeds Act and Regulations. Implementation of the zones policy had beneficial impacts on the potato industry. In contrast, compensation above minimum requirements may set a costly precedent for future disease outbreaks. Dans la présente étude, nous avons analysé les répercussions des flambées de virus PVYn et de galle variqueuse à l'Î.‐P.‐É. sur l'industrie de la pomme de terre. En raison de ces flambées, les producteurs de l'Î.‐P.‐É. ont perdu le marché d'exportation de la pomme de terre de semence vers les États‐Unis. La transformation à valeur ajoutée a aidéà atténuer les répercussions. Les bonifications reçues pour la pomme de terre transformée ont permis aux producteurs de l'Î.‐P.‐É. d'abandonner le marché d'exportation de la pomme de terre de semence et ont contribuéà maintenir la viabilité financière de cette production. Les réactions politiques à ces deux flambées ont inclus: i) l'élaboration de politiques en fonction des zones qui a favorisé la réouverture des marchés étatsuniens; ii) le versement d'indemnisations supérieures à celles prévues par la Loi sur les semences et le Règlement sur les semences. La mise en vigueur de politiques en fonction des zones a eu des effets bénéfiques sur l'industrie. Toutefois, le versement d'indemnisations supérieures aux exigences minimales pourrait créer un précédent coûteux advenant de futures flambées de maladies.
Understanding the Structure of Canadian Farm Incomes in the Design of Safety Net Programs1
Authors: Mussell Al , Moore Terri‐lyn , McEwan Ken , Duffy Randy 
Published: October 2007

The effectiveness of safety net programs in meeting their purpose depends implicitly on the nature of farm profitability distributions. This study provides an empirical characterization of farm operating profit distributions and assesses the implications for Canadian safety net programs. Pooled time series data from the Statistics Canada Tax Data Program and the Farm Financial Survey is queried across a range of farm types and provinces, with quartile distributions of Earnings Before Interest, Taxes, Depreciation, and Amortization (EBITDA) within four farm‐size categories analyzed. The results show that regardless of farm type or province, there is greater variation in operating profit within a sales category than there is across the sales categories, and that the range in operating profit increases with size, revealing some very profitable small farms and unprofitable large farms. Thus, the discussion of the social value of farm stabilization programs ought not to be focused on farm size alone. L'efficacité avec laquelle les programmes de protection du revenu atteignent leurs objectifs dépend implicitement de la nature des distributions de probabilités des fermes. La présente étude établit une caractérisation empirique des distributions du bénéfice d'exploitation agricole et évalue les répercussions sur les programmes de protection du revenu au Canada. Des données chronologiques tirées du Programme des données fiscales (PDF) et de l'Enquête financière sur les fermes (EFF) de Statistique Canada sont totalisées par type de ferme et par province, y compris des distributions par quartile du résultat avant intérêts, impôts et dotations aux amortissements (EBITDA) de quatre catégories de taille de ferme. Les résultats ont montré que, sans égard au type de ferme ou à la province, la variation du bénéfice d'exploitation au sein d'une même catégorie de ventes était supérieure à la variation du bénéfice d'exploitation observée entre les différentes catégories de ventes et que l'étendue du bénéfice d'exploitation augmentait avec la taille, révélant des fermes de petite taille très rentables et des fermes de grande taille non rentables. Par conséquent, la discussion sur la valeur sociale des programmes de stabilisation du revenu agricole ne devrait pas s'appuyer sur la taille de la ferme uniquement.
Effect of exercise duration on ceramide metabolism in the rat heart
Authors: Baranowski M. , Zabielski P. , Blachnio A. , Gorski J. 
Published: October 2007

AbstractAim:  We aimed at gaining more insight into the mechanisms underlying exercise‐induced alterations in myocardial ceramide (CER) content by employing physical activity of various durations and examining all key pathways of CER metabolism.Methods:  The experiments were carried out on male Wistar rats divided into four groups (n = 6 in each case): control, exercised for 30 and 90 min and until exhaustion on the electrically driven treadmill moving with a speed of 1200 m h−1 and set at +10° incline. The animals were anaesthetized and samples of the heart’s left ventricle were excised.Results:  Thirty‐minute exercise decreased the level of CER in the heart by 15%. However, after 90 min of running it returned to the baseline and at the point of exhaustion it exceeded that of the control animals by 26%. The initial reduction in the content of CER was probably a result of its augmented degradation, as a concomitant elevation in the activity of acid ceramidase and the level of sphingosine was observed. The transition from reduction in CER content after 30 min of exercise to its accumulation at the point of exhaustion was a consequence of gradual reduction in the activity of acid ceramidase and simultaneous increase in the rate of de novo CER synthesis, as evidenced by progressive activation of serine palmitoyltransferase and accumulation of sphinganine.Conclusion:  We conclude that the effect of physical effort on myocardial CER content and metabolism depends to a large extent on exercise duration.
Spinal cord long‐term potentiation is attenuated by the NMDA‐2B receptor antagonist Ro 25‐6981
Authors: Pedersen L. M. , Gjerstad J. 
Published: October 2007

AbstractAim: The NR2B‐containingN‐methyl‐d‐aspartate (NMDA) receptors may be involved in a variety of phenomena including synaptic plasticity, memory formation and pain perception. Here we used the NMDA‐2B receptor antagonist Ro 25‐6981 to investigate the role of the NR2B‐containing NMDA receptors in spinal nociception.Methods: Extracellular single unit recordings were performed from dorsal horn wide dynamic range (WDR) neurones in intact urethane‐anaesthetized Sprague–Dawley rats. The responses of the WDR neurones evoked by C‐fibre activation after sciatic nerve stimulation were defined according to latencies. To block the dorsal horn NMDA‐2B receptors, the antagonist Ro 25‐6981 was applied topically onto the spinal cord. High‐frequency stimulation (HFS) of the sciatic nerve was used to induce spinal long‐term potentiation (LTP).Results: Spinal administration of the NMDA‐2B receptor antagonist Ro 25‐6981 had a clear antinociceptive effect at the spinal level (P < 0.05, C‐fibre evoked responses after 4 mmRo 25‐6981 vs. C‐fibre evoked responses in baseline). Moreover, spinal administration of this antagonist clearly attenuated the magnitude of spinal cord LTP after HFS conditioning (P < 0.05, C‐fibre evoked responses after HFS vs. C‐fibre evoked responses after 8 mmRo 25‐6981 + HFS).Conclusion: The present study indicates that expression of full LTP in dorsal horn neurones obtained by HFS conditioning may be dependent on the NMDA receptors containing the NR2B subunit. This suggests that activation of dorsal horn NR2B‐containing NMDA receptors may be involved in use‐dependent sensitization at the spinal level.
Carbon monoxide inhalation reduces skeletal muscle fatigue resistance
Authors: Morse C. I. , Pritchard L. J. , Wüst R. C. I. , Jones D. A. , Degens H. 
Published: October 2007

AbstractAim:  To determine whether inhalation of carbon monoxide (CO), resulting in carboxyhaemoglobin (COHb) levels observed in smokers, had an effect on muscle fatigue during electrically evoked and voluntary muscle contractions.Methods:  Young non‐smoking males inspired CO from a Douglas bag until their COHb level reached 6%. During the control condition the same participants inspired ambient air from a Douglas bag for 6 min. Fatigue was assessed as the decline in torque in isometric knee extensions, during 2 min of electrically evoked contractions (30 Hz, 1 s on, 1 s off) and during 2 min of maximal isometric voluntary contractions (1 s on, 1 s off). A fatigue index (FI) was calculated as the ratio of final torque : initial torque. Time to peak torque (TPT) and half relaxation time (½RT) were also determined for the electrically evoked contractions.Results:  The FI during both the voluntary fatigue test (control: 0.80 ± 0.09 vs. CO: 0.70 ± 0.08; mean ± SD) and that of the fatigue test with electrically evoked contractions (control: 0.61 ± 0.09 vs. CO: 0.53 ± 0.12) was significantly lower after CO inhalation than after inhalation of ambient air (P < 0.05). There was, however, no effect of CO on the changes in TPT or ½RT during the fatigue test.Conclusion:  Carbon monoxide inhalation resulting in COHb levels found in smokers has an acute impact on the ability of the muscle to resist fatigue.
Upregulated expression of S100A6 in human gastric cancer
Authors: YANG Yan Qing , ZHANG Lan Jing , DONG Hui , JIANG Chang Long , ZHU Zheng Gang , WU Jian Xin , WU Yun Lin , HAN Jun Song , XIAO Hua Sheng , GAO Heng Jun , ZHANG Qing Hua 
Published: October 2007

OBJECTIVE:  The expression of S100A6 (calcyclin), a member of the S100 calcium binding protein family, is elevated in a number of malignant tumors, but there have been few reports about its expression in gastric cancer. The aim of this study was to investigate its expression regulations in human gastric cancer and noncancerous mucosa, and the response to chemotherapeutic drugs in the gastric cancer cell line.MATERIALS AND METHODS:  In one matched gastric cancer sample pair, the serial analysis of gene expression (SAGE) experiment was conducted to compare the gene expression profiles between cancerous and adjacent tissues. To detect the expression regulations among more cancerous tissues, microarrays were carried out and real‐time RT‐PCR was conducted to validate the results. At the protein level, Western blot and tissue microarray (TMA) examination were further used to verify S100A6 expression. The regulation detection of S100A6 with flurouracil and doxorubicin at the mRNA and protein level was performed in the SGC7901 cell line.RESULTS:  With the SAGE strategy, five times more S100A6 tags were identified in cancer tissues than in normal tissues. With the cDNA microarray, S100A6 was found to be significantly upregulated in 21 of 42 (50%) nonselective gastric cancers. In 10 other paired samples, the upregulation of S100A6 was consolidated with RT‐PCR and Western blot analysis as well. A total of 14 endoscopy‐sectioned gastric noncancerous lesions and corresponding normal gastric mucosa were also applied to profile the gene expression; both cDNA microarray and RT‐PCR demonstrated no significant alterations of S100A6 at the mRNA level. TMA examination showed that 34 of 52 (65.4%) cancer samples were positively stained, while only 17 of 80 (21.3%) noncancerous lesions were positively detected and all nine normal mucosae were detected to be negative. An in vitro experiment showed that in the gastric cell line SGC‐7901, S100A6 mRNA was detected to be upregulated from 24 to 72 h after treatment with 5 mg/L 5‐flurouracil or 0.3 mg/L doxorubicin, and there were two wave upregulations of the S100A6 protein.CONCLUSION:  The observed regulated expression of S100A6 suggests that it is associated with gastric cancer tumorigenesis and quantitation of S100A6 is a promising tool for diagnosis of gastric cancer.
Robust Likelihood Methods Based on the Skew‐t and Related Distributions
Authors: Azzalini Adelchi , Genton Marc G. 
Published: October 2007

Summary The robustness problem is tackled by adopting a parametric class of distributions flexible enough to match the behaviour of the observed data. In a variety of practical cases, one reasonable option is to consider distributions which include parameters to regulate their skewness and kurtosis. As a specific representative of this approach, the skew‐t distribution is explored in more detail and reasons are given to adopt this option as a sensible general‐purpose compromise between robustness and simplicity, both of treatment and of interpretation of the outcome. Some theoretical arguments, outcomes of a few simulation experiments and various wide‐ranging examples with real data are provided in support of the claim.
Antimicrobial Resistance in Bacteria from Swiss Veal Calves at Slaughter
Authors: Di Labio E. , Regula G. , Steiner A. , Miserez R. , Thomann A. , Ledergerber U. 
Published: October 2007

SummaryBacteria with antimicrobial resistance can be transferred from animals to humans and may compromise antimicrobial treatment in case of infection. To determine the antimicrobial resistance situation in bacteria from Swiss veal calves, faecal samples from 500 randomly selected calves originating from 129 farms were collected at four big slaughterhouses. Samples were cultured for Escherichia coli, Enterococcus sp. and Campylobacter sp. and isolated strains were tested for antimicrobial susceptibility to selected antimicrobial agents by the minimal inhibitory concentration technique using the broth microdilution method. From 100 farms, data on farm management, animal husbandry and antimicrobial treatments of the calves were collected by questionnaire. Risk factors associated with antimicrobial resistance were identified by logistic regression. In total, 467 E. coli, 413 Enterococcus sp. and 202 Campylobacter sp. were isolated. Of those, 68.7%, 98.7% and 67.8%, respectively, were resistant to at least one of the tested antimicrobial agents. Resistance was mainly observed to antimicrobials frequently used in farm animals. Prevalence of resistance to antimicrobials important for human treatment was generally low. However, a rather high number of quinupristin/dalfopristin‐resistant Enterococcus faecium and ciprofloxacin‐resistant Campylobacter sp. were detected. External calf purchase, large finishing groups, feeding of milk by‐products and administration of antimicrobials through feed upon arrival of the animals on the farm significantly increased the risk of antimicrobial resistance at farm level. Participation in a quality assurance programme and injection of a macrolide upon arrival of the animals on the farm had a protective effect. The present study showed that veal calves may serve as a reservoir for resistant bacteria. To ensure food safety, veal calves should be included in the national monitoring programme for antimicrobial resistance in farm animals. By improving farm management and calf husbandry the prevalence of resistance may be reduced.
Mosaic Tetracycline Resistance Genes and Their Flanking Regions in
Bifidobacterium thermophilum
and
Lactobacillus johnsonii
Authors: van Hoek Angela H. A. M. , Mayrhofer Sigrid , Domig Konrad J. , Flórez Ana B. , Ammor Mohammed S. , Mayo Baltasar , Aarts Henk J. M. 
Published: October 2007

ABSTRACT

For the first time, mosaic tetracycline resistance genes were identified in
Lactobacillus johnsonii
and in
Bifidobacterium thermophilum
strains. The
L. johnsonii
strain investigated contains a complex hybrid gene,
tet
(O/W/32/O/W/O), whereas the five bifidobacterial strains possess two different mosaic
tet
genes: i.e.,
tet
(W/32/O) and
tet
(O/W). As reported by others, the crossover points of the mosaic
tet
gene segments were found at similar positions within the genes, suggesting a hot spot for recombination. Analysis of the sequences flanking these genes revealed that the upstream part corresponds to the 5′ end of the mosaic open reading frame. In contrast, the downstream region was shown to be more variable. Surprisingly, in one of the
B. thermophilum
strains a third
tet
determinant was identified, coding for the efflux pump Tet(L).
Interactions of Methylene Blue with Human Disulfide Reductases and Their Orthologues fromPlasmodium falciparum
Authors: Buchholz Kathrin , Schirmer R. Heiner , Eubel Jana K. , Akoachere Monique B. , Dandekar Thomas , Becker Katja , Gromer Stephan 
Published: October 2007

ABSTRACTMethylene blue (MB) has experienced a renaissance mainly as a component of drug combinations againstPlasmodium falciparummalaria. Here, we report biochemically relevant pharmacological data on MB such as rate constants for the uncatalyzed reaction of MB at pH 7.4 with cellular reductants like NAD(P)H (k= 4 M−1s−1), thioredoxins (k= 8.5 to 26 M−1s−1), dihydrolipoamide (k= 53 M−1s−1), and slowly reacting glutathione. As the disulfide reductases are prominent targets of MB, optical tests for enzymes reducing MB at the expense of NAD(P)H under aerobic conditions were developed. The product leucomethylene blue (leucoMB) is auto-oxidized back to MB at pH 7 but can be stabilized by enzymes at pH 5.0, which makes this colorless compound an interesting drug candidate. MB was found to be an inhibitor and/or a redox-cycling substrate of mammalian andP. falciparumdisulfide reductases, with thekcatvalues ranging from 0.03 s−1to 10 s−1at 25°C. Kinetic spectroscopy of mutagenized glutathione reductase indicates that MB reduction is conducted by enzyme-bound reduced flavin rather than by the active-site dithiol Cys58/Cys63. The enzyme-catalyzed reduction of MB and subsequent auto-oxidation of the product leucoMB mean that MB is a redox-cycling agent which produces H2O2at the expense of O2and of NAD(P)H in each cycle, turning the antioxidant disulfide reductases into pro-oxidant enzymes. This explains the termssubversive substrateorturncoat inhibitorfor MB. The results are discussed in cell-pathological and clinical contexts.