628 research outputs found

    Standard isotrivial fibrations with pg = q = 1, II

    Get PDF
    A smooth, projective surface S is called a standard isotrivial fibration if there exists a finite group G which acts faithfully on two smooth projective curves C and F so that S is isomorphic to the minimal desingularization of T {colon equals} (C × F) / G. Standard isotrivial fibrations of general type with pg = q = 1 have been classified in [F. Polizzi, Standard isotrivial fibrations with pg = q = 1, J. Algebra 321 (2009),1600-1631] under the assumption that T has only Rational Double Points as singularities. In the present paper we extend this result, classifying all cases where S is a minimal model. As a by-product, we provide the first examples of minimal surfaces of general type with pg = q = 1, KS2 = 5 and Albanese fibration of genus 3. Finally, we show with explicit examples that the case where S is not minimal actually occurs. © 2009 Elsevier B.V. All rights reserved

    The fundamental group and torsion group of Beauville surfaces

    Full text link
    We give a survey on the fundamental group of surfaces isogenous to a higher product. If the surfaces are regular, e.g. if they are Beauville surfaces, the first homology group is a finite group. We present a MAGMA script which calculates the first homology groups of regular surfaces isogenous to a product.Comment: 14 pages; MAGMA script included; v2: minor corrections, final version to appear in the Proceedings of the Conference "Beauville Surfaces and Groups", Newcastle University (UK), 7-9th June 201

    Charging induced asymmetry in molecular conductors

    Full text link
    We investigate the origin of asymmetry in various measured current-voltage (I-V) characteristics of molecules with no inherent spatial asymmetry, with particular focus on a recent break junction measurement. We argue that such asymmetry arises due to unequal coupling with the contacts and a consequent difference in charging effects, which can only be captured in a self-consistent model for molecular conduction. The direction of the asymmetry depends on the sign of the majority carriers in the molecule. For conduction through highest occupied molecular orbitals (i.e. HOMO or p-type conduction), the current is smaller for positive voltage on the stronger contact, while for conduction through lowest unoccupied molecular orbitals (i.e. LUMO or n-type conduction), the sense of the asymmetry is reversed. Within an extended Huckel description of the molecular chemistry and the contact microstructure (with two adjustable parameters, the position of the Fermi energy and the sulphur-gold bond length), an appropriate description of Poisson's equation, and a self-consistently coupled non-equilibrium Green's function (NEGF) description of transport, we achieve good agreement between theoretical and experimental I-V characteristics, both in shape as well as overall magnitude.Comment: length of the paper has been extended (4 pages to 6 pages), two new figures have been added (3 figures to 5 figures), has been accepted for PR

    A Density Matrix-based Algorithm for Solving Eigenvalue Problems

    Full text link
    A new numerical algorithm for solving the symmetric eigenvalue problem is presented. The technique deviates fundamentally from the traditional Krylov subspace iteration based techniques (Arnoldi and Lanczos algorithms) or other Davidson-Jacobi techniques, and takes its inspiration from the contour integration and density matrix representation in quantum mechanics. It will be shown that this new algorithm - named FEAST - exhibits high efficiency, robustness, accuracy and scalability on parallel architectures. Examples from electronic structure calculations of Carbon nanotubes (CNT) are presented, and numerical performances and capabilities are discussed.Comment: 7 pages, 3 figure

    Terahertz detection in single wall carbon nanotubes

    Full text link
    It is reported that terahertz radiation from 0.69 THz to 2.54 THz has been sensitively detected in a device consisting of bundles of metallic carbon nanotubes, quasi-optically coupled through a lithographically fabricated antenna, and a silicon lens. The measured data are consistent with a bolometric process and show promise for operation above 4.2 K.Comment: 9 page

    The Case of Insertional Adductor Tendinopathy of an International-Level 3,000-m Steeplechase Runner

    Get PDF
    Background: Groin pain is a frequent condition among athletes. One of the causes of groin pain is tendinopathy, a frequently diagnosed medical condition, which can also occur in the adductor muscles. Despite the high prevalence of this medical condition among athletes, it is infrequent to observe tendinopathic groin pain in steeplechase runners. The aim of this case study is to describe the case of an international-level 3,000-m steeplechase runner with groin pain, who was subsequently diagnosed with adductor insertional tendinopathy. Case Presentation: We present the case of an Italian 3,000-m steeplechase and long distance runner, Ala Zoghlami (180 cm, 57 kg), with groin pain, diagnosed as insertional adductor tendinopathy. The runner, after manifesting the painful symptomatology, underwent medical screening (ultrasound and MRI). The radiological investigations highlighted adductor tendinopathy. After refraining from training, the runner underwent medical and physical therapy which, in the first phase, did not improve the painful symptomatology. Further evaluation, after 6 months from the initial training cessation, highlighted a case of malocclusion. Such was treated from a dentistry perspective with the creation of a personalized dental bite. Results: A multidisciplinary approach which included medical and physical therapy, osteopathy, and dentistry, in adjunct with refraining from training, was able to reduce the symptomatology and allowed a correct return to run (after 9 months from the first painful manifestation) of the steeplechase runner. To date, Ala Zoghlami has fully recovered and was able to win the 3,000-m steeplechase race during the 2021 national Italian competition

    Submarine Geomorphology and Sedimentary Features around the Egadi Islands (Western Mediterranean Sea)

    Get PDF
    The physiography, the geomorphological features and the sedimentary bedforms offshore Egadi Islands (Italy) have been illustrated and mapped through an integrated analysis of high-resolution bathymetric, seismo-acoustic and sedimentological data. The study area is characterized by a wide, up to 25 km, continental shelf which is separated by a NNW trending linear incision, the Marettimo Channel, along which several erosional and depositional features have been detected and mapped. Sedimentary prograding wedges were detected at water depths between 100-125 m along the shelf margin, which accumulated during sea level fall and lowstand stages of the last glacio-eustatic cycle (post- MIS 5.5). The study detected several slope breaks defining scarps across the continental shelf, which were interpreted as coastal cliffs that originated during the post-LGM eustatic sea level rise. Several fields of different types of sedimentary bedforms, including 2-D and 3-D hydraulic dunes and sorted bedforms, were found across the continental shelf, providing evidence of a high hydrodynamic regime affecting the seafloor. Further on, the study recognized erosive and depositional features related to bottom currents (contourites) in the Marettimo Channel. These findings provide a better understanding of the morpho-sedimentary evolution of the Egadi Islands offshore in the latest Quaternary. Moreover, they offer essential scientific support for effectively managing the most valuable priority habitats for conservation , such as Posidonia oceanica meadow and coralline algae bioconstructions (Coralligenous habitat)

    On-site magnetization in open antiferromagnetic chains: a classical analysis versus NMR experiments in a spin-1 compound

    Full text link
    The response of an open spin chain with isotropic antiferromagnetic interactions to a uniform magnetic field is studied by classical Monte Carlo simulations. It is observed how the induced on-site magnetization is non uniform, due to the occurrence of edge staggered terms which decay exponentially over a distance equal to the zero field correlation length of the infinite chain. The total magnetic moment associated to each staggered term is found to be about half of the original single-spin magnitude and to decrease as the inverse of temperature (i.e. to behave as a Curie-like moment). The numerical results are compared to recent NMR findings in spinless-doped Y(2)BaNiO(5); the remarkable agreement found shows that, for temperatures above the Haldane gap, the classical approach gives a correct picture of the boundary effects observed in the Heisenberg S=1 chain.Comment: 4 pages, 4 eps figures; minor changes in the text; added reference

    Impact of Periodontitis on Glycemic Control and Metabolic Status in Diabetes Patients: Current Knowledge on Early Disease Markers and Therapeutic Perspectives

    Get PDF
    Diabetes mellitus and periodontitis are two of the most common chronic diseases affecting the world's population, and they are intimately linked. For several years, in fact, it has been known that there is an interdependent relationship between the two diseases: Diabetes promotes the destruction of periodontal tissues, and periodontal disease negatively affects glycemic control. In relation to the control of dental plaque and oral dysbiosis responsible for periodontal disease, both nonsurgical and surgical therapy associated with proper home hygiene procedures have emerged as essential for good glycemic control. Moreover, several evidences suggest the essential role played by the control of periodontal disease in preventing the onset of the most common complications of diabetes: cardiovascular diseases, retinopathies, and other systemic diseases. The aim of this study is to update the current knowledge on the bi-univocal relationship between diabetes and periodontitis and the impact of therapy in the optimal management of these two disorders. From the information found in the literature, it has emerged that the correct treatment of periodontal disease in diabetic patients represents one of the main mechanisms and means currently established and valid to control periodontal disease and glucose metabolism and prevent the onset or development of diabetic complications

    Evidence that muscle cells do not express the histidine-rich glycoprotein associated with AMP deaminase but can internalise the plasma protein

    Get PDF
    Histidine-rich glycoprotein (HRG) is synthesized by liver and is present at relatively high concentration in the plasma of vertebrates. We have previously described the association of a HRG-like molecule to purified rabbit skeletal muscle AMP deaminase (AMPD). We also provided the first evidence for the presence of a HRG-like protein in human skeletal muscle where a positive correlation between HRG content and total determined AMPD activity has been shown. In the present paper we investigate the origin of skeletal muscle HRG. The screening of a human skeletal muscle cDNA expression library using an anti-HRG antibody failed to reveal any positive clone. The RT-PCR analysis, performed on human skeletal muscle RNA as well as on RNA from the rhabdomyosarcoma (RD) cell line, failed to show any mRNA specific for the plasma HRG or for the putative muscle variant. When the RD cells were incubated with human plasma HRG, a time-dependent increase of the HRG immunoreactivity was detected both at the plasma membrane level and intracellularly. The internalisation of HRG was inhibited by the addition of heparin. The above data strongly suggest that skeletal muscle cells do not synthesize the muscle variant of HRG but instead can actively internalise it from plasma
    • …
    corecore