1,456 research outputs found

    Betti maps, Pell equations in polynomials and almost-Belyi maps

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    We study the Betti map of a particular (but relevant) section of the family of Jacobians of hyperelliptic curves using the polynomial Pell equation A(2) - DB2 = 1, with A, B, D is an element of C[t] and certain ramified covers P-1 -> P-1 arising from such equation and having heavy constrains on their ramification. In particular, we obtain a special case of a result of Andre, Corvaja and Zannier on the submersivity of the Betti map by studying the locus of the polynomials D that fit in a Pell equation inside the space of polynomials of fixed even degree. Moreover, Riemann existence theorem associates to the abovementioned covers certain permutation representations: We are able to characterize the representations corresponding to 'primitive' solutions of the Pell equation or to powers of solutions of lower degree and give a combinatorial description of these representations when D has degree 4. In turn, this characterization gives back some precise information about the rational values of the Betti map

    Hyperelliptic continued fractions and generalized jacobians: Minicourse given by Umberto Zannier

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    These are notes from the minicourse given by Umberto Zannier (Scuola Normale Superiore di Pisa). The notes were worked out by Laura Capuano, Peter Jossen,1 Christina Karolus, and Francesco Veneziano. Most of the material of these lectures, except for the numerical examples which were added by us, is already available in [45], The authors wish to thank Umberto Zannier for the lively discussions in Alpbach, and Olaf Merkert for providing computations of the examples 3.17, 3.28, 3.29, 3.33, and 3.25

    Unicentric or multicentric castleman disease? A case report of a pelvic intraperitoneal mass in a middle aged woman

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    Castleman Disease is a lymphoid disorder characterized by the presence of an enlarged or abnormal lymph node/lymphatic tissue. The disease is classified into unicentric or multicentric variants. The unicentric form is a benign disorder that is usually asymptomatic and consists of a single lymphoid mass that is predominantly located in the mediastinum, but can also rarely develop in the neck or abdomen. The multicentric type involves more than one lymphatic station and is related to the presence of type B symptoms (fevers, night sweats and weight loss), HIV/HHV8 infection and increased serum IL-6 levels. We present the case of an unusual pelvic intraperitoneal manifestation of Castleman Disease in a 52-year-old caucasian woman who showed clinical, radiological, histological and laboratory findings common to both Unicentric and Multicentric Castleman Disease

    Chlamydophila pecorum in fetuses of mediterranean buffalo (bubalus bubalis) bred in Italy

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    In order to study the role played by the different species of Chlamydophila in causing abortions in Mediterranean buffalo, the Authors examined 164 fetuses from 80 different buffalo herds in Southern Italy. Three fetuses, came from two different herds, were positive. Our study confirms the pathogenic role of C. pecorum in buffalo, not only as a cause of neuropathology in calves but as an infectious abortive agent

    The New Paradigms in Clinical Research: From Early Access Programs to the Novel Therapeutic Approaches for Unmet Medical Needs.

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    Despite several innovative medicines gaining worldwide approval in recent years, there are still therapeutic areas for which unsatisfied therapeutic needs persist. For example, high unmet clinical need was observed in patients diagnosed with type 2 diabetes mellitus and hemophilia, as well as in specific age groups, such as the pediatric population. Given the urgent need to improve the therapy of clinical conditions for which unmet clinical need is established, clinical testing, and approval of new medicines are increasingly being carried out through accelerated authorization procedures. Starting from 1992, the Food and Drug Administration and the European Medicines Agency have supported the so-called Early Access Programs (EAPs). Such procedures, which can be based on incomplete clinical data, allow an accelerated marketing authorization for innovative medicines. The growth in pharmaceutical research has also resulted in the development of novel therapeutic approaches, such as biotech drugs and advanced therapy medicinal products, including new monoclonal antibodies for the treatment of asthma, antisense oligonucleotides for the treatment of Duchenne muscular dystrophy and spinal muscular atrophy, and new anticancer drugs that act on genetic biomarkers rather than any specific type of cancer. Even though EAPs and novel therapeutic approaches have brought huge benefits for public health, their implementation is limited by several challenges, including the high risk of safety-related label changes for medicines authorized through the accelerated procedure, the high costs, and the reimbursement and access concerns. In this context, regulatory agencies should provide the best conditions for the implementation of the described new tools

    Efficient adaptive pseudo-symplectic numerical integration techniques for Landau-Lifshitz dynamics

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    Numerical time integration schemes for Landau-Lifshitz magnetization dynamics are considered. Such dynamics preserves the magnetization amplitude and, in the absence of dissipation, also implies the conservation of the free energy. This property is generally lost when time discretization is performed for the numerical solution. In this work, explicit numerical schemes based on Runge-Kutta methods are introduced. The schemes are termed pseudo-symplectic in that they are accurate to order p, but preserve magnetization amplitude and free energy to order q > p. An effective strategy for adaptive time-stepping control is discussed for schemes of this class. Numerical tests against analytical solutions for the simulation of fast precessional dynamics are performed in order to point out the effectiveness of the proposed methods

    A minimum-dissipation time-integration strategy for large-eddy simulation of incompressible turbulent flows

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    Adaptive time stepping can significantly enhance the accuracy and the efficiency of computational methods. In this work, a time-integration strategy with adaptive time step control is proposed for large-eddy simulation of turbulent flows. The algorithm is based on Runge-Kutta methods and consists in adjusting the time-step size dynamically to ensure that the numerical dissipation rate due to the temporal scheme is smaller than the molecular and subgrid-scale ones within a desired tolerance. The effectiveness of the method, as compared to standard CFL-like criteria, is assessed by large-eddy simulations of the three-dimensional Taylor-Green Vortex

    Increased IGF-1: IGFBP-3 ratio in patients with hepatocellular carcinoma

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    BACKGROUND: The development of hepatocellular carcinoma in liver cirrhosis is associated with altered synthesis and secretion of several growth factors. AIM: The aim of this prospective study was to investigate the potential implication of IGF-I and its major binding protein (IGFBP-3) in the development of hepatocellular carcinoma. PATIENTS AND METHODS: IGF-I and IGFBP-3 were measured in 150 healthy subjects, 40 patients with liver cirrhosis and 63 with liver cirrhosis and untreated hepatocellular carcinoma. The ratio between IGF-I and IGFBP-3 was also calculated. RESULTS: Serum IGF-I (70 ± 10 and 65 ± 7 vs. 185 ± 6.4 μg/l, P < 0.001) and IGFBP-3 levels (1225 ± 113 and 984 ± 67 vs. 3017 ± 80 μg/l, P < 0.001) were lower in patients with liver cirrhosis, without or with hepatocellular carcinoma, than in controls. Age was negatively correlated with IGF-I levels In patients with liver cirrhosis (r = -0.6; P = 0.0002) as well as in controls (r = -0.8, P < 0.0001), but not in patients with hepatocellular carcinoma (r = -0.2; P = 0.2). Additionally, in patients with liver cirrhosis (r = -0.54; P = 0.0003) and more weakly in those with hepatocellular carcinoma (r = -0.24; P = 0.04) IGF-I levels were negatively correlated with liver failure measured according with Child class. Despite patients with class C hepatocellular carcinoma being older than those in the same functional class with cirrhosis (64 ± 2 vs. 57 ± 2 years, P < 0.01), they had a significantly increased IGF-I : IGFBP-3 ratio (0.18 ± 0.05 vs. 0.41 ± 0.09, P = 0.04), due mostly to increased IGF-I levels (27.1 ± 5.6 vs. 42 ± 6.2 μg/l) as IGFBP-3 levels were similar to patients with cirrhosis (734 ± 81 vs. 679 ± 83 μg/l). CONCLUSIONS: Hepatocellular carcinoma is associated with a higher IGF-I : IGFBP-3 ratio than that found in patients with liver cirrhosis and a similar degree of liver failure
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