Tourism, Economic Expansion and Poverty in Nicaragua: Investigating Cointegration and Causal Relations

Replaced with revised version of paper 09/10/07.Food Security and Poverty, International Development,

Metabolism of amino acid amides in Pseudomonas putida ATCC 12633

The metabolism of the natural amino acid L-valine, the unnatural amino acids D-valine, and D-, L-phenylglycine (D-, L-PG), and the unnatural amino acid amides D-, L-phenylglycine amide (D, L-PG-NH2) and L-valine amide (L-Val-NH2) was studied in Pseudomonas putida ATCC 12633. The organism possessed constitutive L-amidase activities towards L-PG-NH2 and L-Val-NH2, both following the same pattern of expression, suggesting the involvement of similarly regulated enzymes, or a common enzyme. Quite surprisingly, growth in mineral media with L-PG-NH2 resulted in variable, long lag phases of growth and strongly reduced L-amidase activities. Conversion of D-PG-NH2 into D-PG and L-PG also occurred and could be attributed to the presence of an inducible D-amidase and the racemization of the amino acid amide in combination with L-amidase activity, respectively. The further degradation of L-PG and D-PG involved constitutive L-PG aminotransferase and inducible D-PG dehydrogenase activities, respectively, both with a high degree of enantioselectivity. Amino acid racemase activity for D- and L-PG was not detected.

Characterization of bacterial communities associated with Brassica napus L. growing on a Zn-contaminated soil and their effects on root growth

peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=bijp20The attached document is the author's final accepted/submitted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it

An optimization model for metabolic pathways

This article is available open access through the publisher’s website through the link below. Copyright @ The Author 2009.Motivation: Different mathematical methods have emerged in the post-genomic era to determine metabolic pathways. These methods can be divided into stoichiometric methods and path finding methods. In this paper we detail a novel optimization model, based upon integer linear programming, to determine metabolic pathways. Our model links reaction stoichiometry with path finding in a single approach. We test the ability of our model to determine 40 annotated Escherichia coli metabolic pathways. We show that our model is able to determine 36 of these 40 pathways in a computationally effective manner. Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics online (http://bioinformatics.oxfordjournals.org/cgi/content/full/btp441/DC1)

Modelling Tourism Development and Long-run Economic Growth in Aruba

Tourism has over the past decades turned into a core activity for accelerated growth. The purpose of this study is to determine the role of tourism in the economy of Aruba. More specifically, this investigation attempts to answer the following questions: (1) is there is a long-run equilibrium relation between tourism development (TD) and economic growth in Aruba?; and (2) if so, what is the causality direction between TD and economic growth? This exercise involves applying an econometric methodology consisting of unit root testing, cointegration analysis, vector error correction modeling (VECM), and Granger causality testing. The results show there is one cointegrating relation between these two variables, while the VECM comprises both a short- and a long-run relation. The short-run dynamics of the model suggests a speed of correction of 0.25%, meaning that it would take about 10.5 years to correct for disturbances back to equilibrium. The long-run relation indicates that a 1% change in tourism revenues would lead to a 0.49% increase in real GDP in the long-run, ceteris paribus. Our findings have also empirically verified the presence of the Tourism-Led Growth Hypothesis (TLGH) in the case of Aruba. They show that tourism is in part an endogenous growth process, requiring a systematic allocation of resources (e.g., financial means, leadership, creativity, innovation, and entrepreneurship) to sustain its development for local and regional economies

Neurobehavioral function and low-level exposure to brominated flame retardants in adolescents : a cross-sectional study

Background: Animal and in vitro studies demonstrated a neurotoxic potential of brominated flame retardants, a group of chemicals used in many household and commercial products to prevent fire. Although the first reports of detrimental neurobehavioral effects in rodents appeared more than ten years ago, human data are sparse. Methods: As a part of a biomonitoring program for environmental health surveillance in Flanders, Belgium, we assessed the neurobehavioral function with the Neurobehavioral Evaluation System (NES-3), and collected blood samples in a group of high school students. Cross-sectional data on 515 adolescents (13.6-17 years of age) was available for the analysis. Multiple regression models accounting for potential confounders were used to investigate the associations between biomarkers of internal exposure to brominated flame retardants [serum levels of polybrominated diphenyl ether (PBDE) congeners 47, 99, 100, 153, 209, hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA)] and cognitive performance. In addition, we investigated the association between brominated flame retardants and serum levels of FT3, FT4, and TSH. Results: A two-fold increase of the sum of serum PBDE's was associated with a decrease of the number of taps with the preferred-hand in the Finger Tapping test by 5.31 (95% CI: 0.56 to 10.05, p = 0.029). The effects of the individual PBDE congeners on the motor speed were consistent. Serum levels above the level of quantification were associated with an average decrease of FT3 level by 0.18 pg/mL (95% CI: 0.03 to 0.34, p = 0.020) for PBDE-99 and by 0.15 pg/mL (95% CI: 0.004 to 0.29, p = 0.045) for PBDE-100, compared with concentrations below the level of quantification. PBDE-47 level above the level of quantification was associated with an average increase of TSH levels by 10.1% (95% CI: 0.8% to 20.2%, p = 0.033), compared with concentrations below the level of quantification. We did not observe effects of PBDE's on neurobehavioral domains other than the motor function. HBCD and TBBPA did not show consistent associations with performance in the neurobehavioral tests. Conclusions: This study is one of few studies and so far the largest one investigating the neurobehavioral effects of brominated flame retardants in humans. Consistently with experimental animal data, PBDE exposure was associated with changes in the motor function and the serum levels of the thyroid hormones