79,086 research outputs found

    On structure constants with two spinning twist-two operators

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    I consider three-point functions of one protected and two unprotected twist-two operators with spin in N=4 SYM at weak coupling. At one loop I formulate an empiric conjecture for the dependence of the corresponding structure constants on the spins of the operators. Using such an ansatz and some input from explicit perturbative results, I fix completely various infinite sets of one-loop structure constants of these three-point functions. Finally, I determine the two-loop corrections to the structure constants for a few fixed values of the spins of the operators.Comment: 21 page

    Physics with charged kaons: recent and future experiments

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    This paper summarizes some recent progress and future perspectives in the experimental investigation of the Standard Model (and physics beyond it) using charged kaon decays, except for the important mode K+ -> pi+ nu nubar discussed in detail in other contributions to this workshop.Comment: Invited talk at the Workshop on e+e- in the 1-2 GeV range, Alghero, Italy, September 2003 (eConf C0309101). 5 pages, 3 figures. Added and corrected some reference

    Parallel Implementation of Efficient Search Schemes for the Inference of Cancer Progression Models

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    The emergence and development of cancer is a consequence of the accumulation over time of genomic mutations involving a specific set of genes, which provides the cancer clones with a functional selective advantage. In this work, we model the order of accumulation of such mutations during the progression, which eventually leads to the disease, by means of probabilistic graphic models, i.e., Bayesian Networks (BNs). We investigate how to perform the task of learning the structure of such BNs, according to experimental evidence, adopting a global optimization meta-heuristics. In particular, in this work we rely on Genetic Algorithms, and to strongly reduce the execution time of the inference -- which can also involve multiple repetitions to collect statistically significant assessments of the data -- we distribute the calculations using both multi-threading and a multi-node architecture. The results show that our approach is characterized by good accuracy and specificity; we also demonstrate its feasibility, thanks to a 84x reduction of the overall execution time with respect to a traditional sequential implementation

    The Birth of a New Industry: Entry by Start-ups and the Drivers of Firm Growth. The Case of Encryption Software

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    The paper analyses the birth of the Encryption Software Industry (ESI), a new niche in the software industry. Using a Chandlerian perspective, this work reports the main facts about firm entry and growth, with a particular focus on start-up strategies and actions. Since scale economies do not play a major role in ESI, the paper investigates the different sources of firm competitive advantages. This work shows that innovation and product differentiation, along with investments in co-specialised assets, are variables strongly correlated to young firm probability to survive and grow. In so doing, we have collected highly detailed information on product introduction, US patents granted, worldwide alliances and biographical data of firm founders.Entry, Entrepreneurship, Innovation, Software.

    ABJM θ\theta-Bremsstrahlung at four loops and beyond: non-planar corrections

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    We consider the Bremsstrahlung function associated to a 1/6-BPS Wilson loop in ABJM theory, with a cusp in the couplings to scalar fields. We non-trivially extend its recent four-loop computation at weak coupling to include non-planar corrections. We have recently proposed a conjecture relating this object to supersymmetric circular Wilson loops with multiple windings, which can be computed via localization. We find agreement between this proposal and the perturbative computation of the Bremsstrahlung function, including color sub-leading corrections. This supports the conjecture and hints at its validity beyond the planar approximation.Comment: 22 page

    Diagnosis and management of treatment-refractory hypothyroidism: an expert consensus report

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    There is a frequently encountered subset of hypothyroid patients who are refractory to standard thyroid hormone replacement treatment and require unexpectedly high doses of levothyroxine. In addition to clinical situations where hypothyroid patients are non-compliant, or where there is the possibility of excipient-induced disease exacerbation (gluten/celiac disease), therapeutic failure may be due to impaired absorption of the administered drug. The common approach to managing patients with unusual thyroxine needs is to escalate the dose of levothyroxine until targeted TSH levels are achieved. This approach can increase the risk for prolonged exposure to supratherapeutic doses of levothyroxine, which increase the chances of adverse outcomes. Repeated adjustments of levothyroxine can also escalate the costs of treatment, as frequent office visits and laboratory tests are required to determine and maintain the desired dose. Clinicians should take a systematic approach to managing patients whom they suspect of having treatment-refractory hypothyroidism. This may include searching for, and adjusting, occult medical conditions and/or other factors that may affect the absorption of levothyroxine, before up-titrating the dose of traditional levothyroxine therapy. Depending on the underlying pathology, another approach that may be considered is to try alternative formulations of levothyroxine that are less susceptible to intolerance issues related to excipients, or, in some cases, to malabsorption. The early discovery of these factors via a thoughtful patient work-up may avoid unnecessary thyroid medication adjustments and their consequences for both patients and clinicians

    QCD and spin effects in black hole airshowers

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    In models with large extra dimensions, black holes may be produced in high-energy particle collisions. We revisit the physics of black hole formation in extensive airshowers from ultrahigh-energy cosmic rays, focusing on collisional QCD and black hole emissivity effects. New results for rotating black holes are presented. Monte Carlo simulations show that QCD effects and black hole spin produce no observable signatures in airshowers. These results further confirm that the main characteristics of black hole-induced airshowers do not depend on the fine details of micro black hole models.Comment: 6 pages, 2 figures, accepted for publication in Physical Review
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