267 research outputs found

    Relaxation of classical many-body hamiltonians in one dimension

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    The relaxation of Fourier modes of hamiltonian chains close to equilibrium is studied in the framework of a simple mode-coupling theory. Explicit estimates of the dependence of relevant time scales on the energy density (or temperature) and on the wavenumber of the initial excitation are given. They are in agreement with previous numerical findings on the approach to equilibrium and turn out to be also useful in the qualitative interpretation of them. The theory is compared with molecular dynamics results in the case of the quartic Fermi-Pasta-Ulam potential.Comment: 9 pag. 6 figs. To appear in Phys.Rev.

    IKZF1 Deletions with COBL Breakpoints Are Not Driven by RAG-Mediated Recombination Events in Acute Lymphoblastic Leukemia

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    IKZF1 deletion (ΔIKZF1) is an important predictor of relapse in both childhood and adult B-cell precursor acute lymphoblastic leukemia (B-ALL). Previously, we revealed that COBL is a hotspot for breakpoints in leukemia and could promote IKZF1 deletions. Through an international collaboration, we provide a detailed genetic and clinical picture of B-ALL with COBL rearrangements (COBL-r). Patients with B-ALL and IKZF1 deletion (n = 133) were included. IKZF1 ∆1-8 were associated with large alterations within chromosome 7: monosomy 7 (18%), isochromosome 7q (10%), 7p loss (19%), and interstitial deletions (53%). The latter included COBL-r, which were found in 12% of the IKZF1 ∆1-8 cohort. Patients with COBL-r are mostly classified as intermediate cytogenetic risk and frequently harbor ETV6, PAX5, CDKN2A/B deletions. Overall, 56% of breakpoints were located within COBL intron 5. Cryptic recombination signal sequence motifs were broadly distributed within the sequence of COBL, and no enrichment for the breakpoint cluster region was found. In summary, a diverse spectrum of alterations characterizes ΔIKZF1 and they also include deletion breakpoints within COBL. We confirmed that COBL is a hotspot associated with ΔIKZF1, but these rearrangements are not driven by RAG-mediated recombination

    A Multicriteria Analysis on the Strategies to Open Taiwan's Mobile Virtual Network Operators Services

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    [[abstract]]This study investigates the trends followed by MVNOs (Mobile Virtual Network Operators) in the last three years and analyzes the strategies that can contribute to the success of Taiwan's telecommunications industry and marketing. We apply the method and concept of PATTERN (Planning Assistance Through Technical Evaluation of Relevance Number) to establish relevant systems for searching out the key successful factors of strategies to attract MVNOs. We also use the fuzzy Multi-Criteria Decision Making (MCDM) method for analyzing the different preference of a decision group in the criteria weights and for ranking the alternatives in a fuzzy environment in order to provide a strategy scheme. These results provide a reference to assist telecommunications operators, 3G license owners, potential MVNOs, and equipment manufacturers when working out business plans.[[incitationindex]]SCI[[booktype]]箙

    Multidimensional Facets of Perceived Risk in Mobile Travel Booking

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    Despite the growing prevalence of smartphones in daily life and travel context, travellers still perceive an extent of risk associated with using their smartphone to book travel products. In order to alleviate or reduce perceived risk, it is important to better understand the dimensions of and the factors that contribute to perceived risk. This study analysed 411 responses from an online panel to examine perceived risk in mobile travel booking and identified the following facets: time risk, financial risk, performance risk, privacy/security risk, psychological risk, physical risk, and device risk. Several antecedents of perceived risk were identified. Perceived collection of personal information via smartphones contributes positively, while consumer innovativeness, trust, and visibility contribute negatively to perceived risk. Further, the predictive validity of perceived risk is confirmed as it significantly explains perceived usefulness, attitude, and behavioural intention in mobile travel booking. Implications to manage perceived risk and its antecedents are provided

    Molecular Evolution and Functional Diversification of Fatty Acid Desaturases after Recurrent Gene Duplication in Drosophila

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    Frequent gene duplications in the genome incessantly supply new genetic materials for functional innovation presumably driven by positive Darwinian selection. This mechanism in the desaturase gene family has been proposed to be important in triggering the pheromonal diversification in insects. With the recent completion of a dozen Drosophila genomes, a genome-wide perspective is possible. In this study, we first identified homologs of desaturase genes in 12 Drosophila species and noted that while gene duplication events are relatively frequent, gene losses are not scarce, especially in the desat1–desat2–desatF clade. By reconciling the gene tree with species phylogeny and the chromosomal synteny of the sequenced Drosophila genomes, at least one gene loss in desat2 and a minimum of six gene gains (resulting in seven desatF homologs, α-η), three gene losses and one relocation in desatF were inferred. Upon branching off the ancestral desat1 lineage, both desat2 and desatF gained novel functions through accelerating protein evolution. The amino acid residues under positive selection located near the catalytic sites and the C-terminal region might be responsible for altered substrate selectivity between closely related species. The association between the expression pattern of desatF-α and the chemical composition of cuticular hydrocarbons implies that the ancestral function of desatF-α is the second desaturation at the four carbons after the first double bond in diene synthesis, and the shift from bisexual to female-specific expression in desatF-α occurred in the ancestral lineage of Drosophila melanogaster subgroup. A relationship between the number of expressed desatF homologs and the diene diversification has also been observed. These results suggest that the molecular diversification of fatty acid desaturases after recurrent gene duplication plays an important role in pheromonal diversity in Drosophila

    Expression of Foxp3 in colorectal cancer but not in Treg cells correlates with disease progression in patients with colorectal cancer

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    Background: Regulatory T cells (Treg) expressing the transcription factor forkhead-box protein P3 (Foxp3) have been identified to counteract anti-tumor immune responses during tumor progression. Besides, Foxp3 presentation by cancer cells itself may also allow them to evade from effector T-cell responses, resulting in a survival benefit of the tumor. For colorectal cancer (CRC) the clinical relevance of Foxp3 has not been evaluated in detail. Therefore the aim of this study was to study its impact in colorectal cancer (CRC). Methods and Findings: Gene and protein analysis of tumor tissues from patients with CRC was performed to quantify the expression of Foxp3 in tumor infiltrating Treg and colon cancer cells. The results were correlated with clinicopathological parameters and patients overall survival. Serial morphological analysis demonstrated Foxp3 to be expressed in cancer cells. High Foxp3 expression of the cancer cells was associated with poor prognosis compared to patients with low Foxp3 expression. In contrast, low and high Foxp3 level in tumor infiltrating Treg cells demonstrated no significant differences in overall patient survival. Conclusions: Our findings strongly suggest that Foxp3 expression mediated by cancer cells rather than by Treg cells contribute to disease progression

    Analysis of efficiency and profitability of franchise services

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    The present study analyses the relative efficiency of franchise services and characterises the best companies, confirming the relationship between efficiency and profit. These companies are from the trade and other services sector , the main group of service-providing companies in the Spanish economy. The methodology calls for first comparing the relative efficiency of franchisers and ownership enterprises. Second, the focus turns to the most efficient franchise services, using a super-efficiency model to rank them. The paper then goes on to cover the analysis of the main characteristics of the best franchise enterprises, the number of own establishments in a franchise business and the profitability of the company. This paper presents arguments as to why companies from the trade and other services sector are included. The main conclusion is that, whilst the number of establishments is irrelevant in achieving greater efficiency, many of the most efficient enterprises have high returns.GarcĂ­a Martin, CJ.; Medal Bartual, A.; Peris-Ortiz, M. (2014). Analysis of efficiency and profitability of franchise services. Service Industries Journal. 34(9):796-810. doi:10.1080/02642069.2014.905921S79681034

    IKZF1 Deletions with COBL Breakpoints Are Not Driven by RAG-Mediated Recombination Events in Acute Lymphoblastic Leukemia

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    IKZF1 deletion (ΔIKZF1) is an important predictor of relapse in both childhood and adult B-cell precursor acute lymphoblastic leukemia (B-ALL). Previously, we revealed that COBL is a hotspot for breakpoints in leukemia and could promote IKZF1 deletions. Through an international collaboration, we provide a detailed genetic and clinical picture of B-ALL with COBL rearrangements (COBL-r). Patients with B-ALL and IKZF1 deletion (n = 133) were included. IKZF1 ∆1-8 were associated with large alterations within chromosome 7: monosomy 7 (18%), isochromosome 7q (10%), 7p loss (19%), and interstitial deletions (53%). The latter included COBL-r, which were found in 12% of the IKZF1 ∆1-8 cohort. Patients with COBL-r are mostly classified as intermediate cytogenetic risk and frequently harbor ETV6, PAX5, CDKN2A/B deletions. Overall, 56% of breakpoints were located within COBL intron 5. Cryptic recombination signal sequence motifs were broadly distributed within the sequence of COBL, and no enrichment for the breakpoint cluster region was found. In summary, a diverse spectrum of alterations characterizes ΔIKZF1 and they also include deletion breakpoints within COBL. We confirmed that COBL is a hotspot associated with ΔIKZF1, but these rearrangements are not driven by RAG-mediated recombination
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