3,013 research outputs found

    FDI in Space: Spatial Autoregressive Relationships in Foreign Direct Investment

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    Theoretical models of foreign direct investment (FDI) have only recently begun to model the role of third countries, and the empirical FDI literature has almost exclusively examined bilateral FDI data without recognizing the potential interdependence between FDI decisions to alternative host countries. This paper uses spatial econometric techniques to examine the spatial correlation between FDI to alternative (neighboring) regions. The sign of such correlations can provide evidence for or against alternative theories for FDI motivations. Using data on OECD countries from 1980-2000, we find evidence consistent with export platform FDI in Europe.

    Leishmania (Viannia) spp. dissemination and tissue tropism in naturally infected dogs (Canis familiaris).

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    First evidence is presented for Leishmania (Viannia) spp. dissemination and tissue tropism in the domestic dog. Using PCR and histology, parasites were detected in the conjunctiva, lung, lymph nodes and ovaries of 2 naturally infected Peruvian dogs. The detection of parasites in the blood indicates that parasite dissemination to those organs may have been haematogenous

    PPD v1.0—an integrated, web-accessible database of experimentally determined protein pK(a) values

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    The Protein pK(a) Database (PPD) v1.0 provides a compendium of protein residue-specific ionization equilibria (pK(a) values), as collated from the primary literature, in the form of a web-accessible postgreSQL relational database. Ionizable residues play key roles in the molecular mechanisms that underlie many biological phenomena, including protein folding and enzyme catalysis. The PPD serves as a general protein pK(a) archive and as a source of data that allows for the development and improvement of pK(a) prediction systems. The database is accessed through an HTML interface, which offers two fast, efficient search methods: an amino acid-based query and a Basic Local Alignment Search Tool search. Entries also give details of experimental techniques and links to other key databases, such as National Center for Biotechnology Information and the Protein Data Bank, providing the user with considerable background information. The database can be found at the following URL:

    The cell adhesion molecule Fasciclin2 regulates brush border length and organization in Drosophila renal tubules

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    Multicellular organisms rely on cell adhesion molecules to coordinate cell–cell interactions, and to provide navigational cues during tissue formation. In Drosophila, Fasciclin 2 (Fas2) has been intensively studied due to its role in nervous system development and maintenance; yet, Fas2 is most abundantly expressed in the adult renal (Malpighian) tubule rather than in neuronal tissues. The role Fas2 serves in this epithelium is unknown. Here we show that Fas2 is essential to brush border maintenance in renal tubules of Drosophila. Fas2 is dynamically expressed during tubule morphogenesis, localizing to the brush border whenever the tissue is transport competent. Genetic manipulations of Fas2 expression levels impact on both microvilli length and organization, which in turn dramatically affect stimulated rates of fluid secretion by the tissue. Consequently, we demonstrate a radically different role for this well-known cell adhesion molecule, and propose that Fas2-mediated intermicrovillar homophilic adhesion complexes help stabilize the brush border

    Short inverted repeats contribute to localized mutability in human somatic cells.

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    Selected repetitive sequences termed short inverted repeats (SIRs) have the propensity to form secondary DNA structures called hairpins. SIRs comprise palindromic arm sequences separated by short spacer sequences that form the hairpin stem and loop respectively. Here, we show that SIRs confer an increase in localized mutability in breast cancer, which is domain-dependent with the greatest mutability observed within spacer sequences (∼1.35-fold above background). Mutability is influenced by factors that increase the likelihood of formation of hairpins such as loop lengths (of 4-5 bp) and stem lengths (of 7-15 bp). Increased mutability is an intrinsic property of SIRs as evidenced by how almost all mutational processes demonstrate a higher rate of mutagenesis of spacer sequences. We further identified 88 spacer sequences showing enrichment from 1.8- to 90-fold of local mutability distributed across 283 sites in the genome that intriguingly, can be used to inform the biological status of a tumor

    Determining when a hospital admission of an older person can be avoided in a subacute setting: a systematic review and concept analysis

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    Objective To conduct a systematic review of the evidence for when a hospital admission for an older person can be avoided in subacute settings. We examined the definition of admission avoidance and the evidence for the factors that are required to avoid admission to hospital in this setting. Methods Using defined PICOD criteria, we conducted searches in three databases (Medline, Embase and Cinahl) from January 2006 to February 2018. References were screened by title and abstract followed by full paper screening by two reviewers. Additional studies were searched from the grey literature, experts in the field and forward and backward referencing. Data were narratively described, and concept analysis was used to investigate the definition of admission avoidance. Results A total of 17 studies were considered eligible for review; eight provided a definition of admission avoidance and 10 described admission avoidance criteria. We identified three factors which play a key role in admission avoidance in the subacute setting: (1) ambulatory care sensitive conditions and common medical scenarios for the older person, which included respiratory infections or pneumonia, urinary tract infections and catheter care, dehydration and associated symptoms, falls and behavioural management, and managing ongoing chronic conditions; (2) criteria/tools, referring to interventions that have used clinical expertise in conjunction with a range of general and geriatric triage tools; in condition-specific interventions, the decision whether to admit or not was based on level of risk determined by defined clinical tools; and (3) personnel and resources, referring to the need for experts to make the initial decision to avoid an admission. Supervision by nurses or physicians was still needed at subacute level, requiring resources such as short-stay beds, intravenous antibiotic treatment or fluids for rehydration and rapid access to laboratory tests. Conclusion<jats:p/> The review identified a set of criteria for ambulatory care sensitive conditions and common medical scenarios for the older person that can be treated in the subacute setting with appropriate tools and resources. This information can help commissioners and care providers to take on these important elements and deliver them in a locally designed way

    Quantum Loop Subalgebra and Eigenvectors of the Superintegrable Chiral Potts Transfer Matrices

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    It has been shown in earlier works that for Q=0 and L a multiple of N, the ground state sector eigenspace of the superintegrable tau_2(t_q) model is highly degenerate and is generated by a quantum loop algebra L(sl_2). Furthermore, this loop algebra can be decomposed into r=(N-1)L/N simple sl_2 algebras. For Q not equal 0, we shall show here that the corresponding eigenspace of tau_2(t_q) is still highly degenerate, but splits into two spaces, each containing 2^{r-1} independent eigenvectors. The generators for the sl_2 subalgebras, and also for the quantum loop subalgebra, are given generalizing those in the Q=0 case. However, the Serre relations for the generators of the loop subalgebra are only proven for some states, tested on small systems and conjectured otherwise. Assuming their validity we construct the eigenvectors of the Q not equal 0 ground state sectors for the transfer matrix of the superintegrable chiral Potts model.Comment: LaTeX 2E document, using iopart.cls with iopams packages. 28 pages, uses eufb10 and eurm10 fonts. Typeset twice! Version 2: Details added, improvements and minor corrections made, erratum to paper 2 included. Version 3: Small paragraph added in introductio

    Eigenvectors in the Superintegrable Model I: sl_2 Generators

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    In order to calculate correlation functions of the chiral Potts model, one only needs to study the eigenvectors of the superintegrable model. Here we start this study by looking for eigenvectors of the transfer matrix of the periodic tau_2(t)model which commutes with the chiral Potts transfer matrix. We show that the degeneracy of the eigenspace of tau_2(t) in the Q=0 sector is 2^r, with r=(N-1)L/N when the size of the transfer matrix L is a multiple of N. We introduce chiral Potts model operators, different from the more commonly used generators of quantum group U-tilde_q(sl-hat(2)). From these we can form the generators of a loop algebra L(sl(2)). For this algebra, we then use the roots of the Drinfeld polynomial to give new explicit expressions for the generators representing the loop algebra as the direct sum of r copies of the simple algebra sl(2).Comment: LaTeX 2E document, 11 pages, 1 eps figure, using iopart.cls with graphicx and iopams packages. v2: Appended text to title, added acknowledgments and made several minor corrections v3: Added reference, eliminated ambiguity, corrected a few misprint

    Reactivity of penicillin-binding proteins with peptidoglycan-mimetic beta-lactams: what's wrong with these enzymes?

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    Beta-lactams exert their antibiotic action through their inhibition of bacterial DD-peptidases (penicillin-binding proteins). Bacteria, in general, carry several such enzymes localized on the outside of their cell membrane to catalyze the final step in cell wall (peptidoglycan) synthesis. They have been classified into two major groups, one of high molecular weight, the other of low. Members of the former group act as transpeptidases in vivo, and their inhibition by beta-lactams leads to cessation of bacterial growth. The latter group consists of DD-carboxypeptidases, and their inhibition by beta-lactams is generally not fatal to bacteria. We have previously shown that representatives of the former group are ineffective at catalyzing the hydrolysis/aminolysis of peptidoglycan-mimetic peptides in vitro [Anderson et al. (2003) Biochem. J. 373, 949-955]. The theme of these experiments is expanded in the present paper where we describe the synthesis of a series of beta-lactams (penicillins and cephalosporins) containing peptidoglycan-mimetic side chains and the kinetics of their inhibition of a panel of penicillin-binding proteins spanning the major classes (Escherichia coli PBP 2 and PBP 5, Streptococcus pneumoniae PBP 1b, PBP 2x and PBP 3, the Actinomadura R39 DD-peptidase, and the Streptomyces R61 DD-peptidase). The results of these experiments mirror and expand the previous results with peptides. Neither peptides nor beta-lactams with appropriate peptidoglycan-mimetic side chains react with the solubilized constructs of membrane-bound penicillin binding proteins (the first five enzymes above) at rates exceeding those of generic analogues. Such peptides and beta-lactams do react at greatly enhanced rates with certain soluble low molecular weight enzymes (R61 and R39 DD-peptidases). The former result is unexpected and interesting. Why do the majority of penicillin-binding proteins not recognize elements of local peptidoglycan structure? Possible answers are discussed. That this question needs to be asked casts fascinating shadows on current studies of penicillin-binding proteins for new drug design
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