469 research outputs found

    Unbounded Recursion and Non-size-increasing Functions

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    We investigate the computing power of function algebras defined by means of unbounded recursion on notation. We introduce two function algebras which contain respectively the regressive logspace computable functions and the non-size-increasing logspace computable functions. However, such algebras are unlikely to be contained in the set of logspace computable functions because this is equivalent to L=P . Finally, we introduce a function algebra based on simultaneous recursion on notation for the non-size-increasing functions computable in polynomial time and linear space

    Imaging multi-age construction settlement behaviour by advanced SAR interferometry

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    This paper focuses on the application of Advanced Satellite Synthetic Aperture Radar Interferometry (A-DInSAR) to subsidence-related issues, with particular reference to ground settlements due to external loads. Beyond the stratigraphic setting and the geotechnical properties of the subsoil, other relevant boundary conditions strongly influence the reliability of remotely sensed data for quantitative analyses and risk mitigation purposes. Because most of the Persistent Scatterer Interferometry (PSI) measurement points (Persistent Scatterers, PSs) lie on structures and infrastructures, the foundation type and the age of a construction are key factors for a proper interpretation of the time series of ground displacements. To exemplify a methodological approach to evaluate these issues, this paper refers to an analysis carried out in the coastal/deltaic plain west of Rome (Rome and Fiumicino municipalities) affected by subsidence and related damages to structures. This region is characterized by a complex geological setting (alternation of recent deposits with low and high compressibilities) and has been subjected to different urbanisation phases starting in the late 1800s, with a strong acceleration in the last few decades. The results of A-DInSAR analyses conducted from 1992 to 2015 have been interpreted in light of high-resolution geological/geotechnical models, the age of the construction, and the types of foundations of the buildings on which the PSs are located. Collection, interpretation, and processing of geo-thematic data were fundamental to obtain high-resolution models; change detection analyses of the land cover allowed us to classify structures/infrastructures in terms of the construction period. Additional information was collected to define the types of foundations, i.e., shallow versus deep foundations. As a result, we found that only by filtering and partitioning the A-DInSAR datasets on the basis of the above-mentioned boundary conditions can the related time series be considered a proxy of the consolidation process governing the subsidence related to external loads as confirmed by a comparison with results from a physically based back analysis based on Terzaghi's theory. Therefore, if properly managed, the A-DInSAR data represents a powerful tool for capturing the evolutionary stage of the process for a single building and has potential for forecasting the behaviour of the terrain-foundation-structure combination

    Two-dimensional repulsive Fermi polarons with short and long-range interactions

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    We study the repulsive polaron problem in a two-component two-dimensional system of fermionic atoms. We use two different interaction models: a short-range (hard-disk) potential and a dipolar potential. In our approach, all the atoms have the same mass and we consider the system to be composed of a uniform bath of a single species and a single atomic impurity. We use the diffusion Monte Carlo method to evaluate polaron properties such as its chemical potential and pair distribution functions, together with a discussion on the deficit of volume induced by the impurity. We also evaluate observables that allow us to determine the validity of the quasi-particle picture: the quasi-particle residue and the effective mass of the polaron. Employing two different potentials allows us to identify the universality regime, where the properties depend only on the gas parameter nas2n a_s^2 fixed by the bath density and the two-dimensional scattering length

    Conformational Studies by Dynamic NMR. 97.Structure, Conformation, Stereodynamics and Enantioseparation of Aryl Substituted Norbornanes.

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    CAN 140:163414 AN 2003:996217 CAPLUS (COPYRIGHT (C) 2008 ACS ON SCIFINDER (R)) ABSTRACT THE STRUCTURE OF A 1,7,7-TRIARYLNORBORNANE (I) HAS BEEN DETD. BY X-RAY DIFFRACTION AND WAS FOUND ESSENTIALLY EQUAL TO THAT PREDICTED BY MOL. MECHANICS CALCNS. RESTRICTED ROTATION OF THE ARYL GROUPS ALSO HAS BEEN OBSD. BY DYNAMIC NMR SPECTROSCOPY IN THIS COMPD. AND IN A NO. OF ANALOGOUSLY SUBSTITUTED NORBORNANES. THE ARYL-NORBORNANE BOND ROTATION BARRIERS WERE MEASURED BY LINE SHAPE ANAL. OF THE 13C NMR SPECTRA OBTAINED AT TEMPS. LOWER THAN -100 °C AND WERE FOUND TO COVER THE RANGE 6.0 TO 7.9 KCAL MOL-1. AN EXCEPTION WAS THE ROTATION INVOLVING THE O-ANISYL GROUP IN II, WHICH OCCURS NEAR AMBIENT TEMP. SINCE THE CORRESPONDING BARRIER IS MUCH HIGHER (14.4 KCAL MOL-1). IN ONE CASE (III) CONFIGURATIONAL ENANTIOMERS COULD BE SEPD. BY CHIRAL HPLC AND THE CORRESPONDING CD SPECTRA RECORDED

    Sudden death in lambda light chain AL cardiac amyloidosis: a review of literature and update for clinicians and pathologists

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    Light chain (AL) amyloidosis is the most common type of systemic amyloidosis, affecting around 10 people per million per year. In Europe, approximately 5000 new diagnosis per year are reported. Deposition of amyloid fibrils derived from antibody light chains are key pathogenic agents in AL amyloidosis. They can be deposited in multiple organs but cardiac involvement carries a major risk of mortality. The prognosis is poor in cases associated with multiple myeloma. The average survival is around 1 year. Up to half of all patients with cardiac amyloidosis die suddenly; 75% ofthose deaths are due to heart failure. Ventricular arrhythmia is also associated with cardiac amyloidosis and unexpected death. It is crucial to make a diagnosis and start treatment at an early stage. Recent data suggest that cardiac amyloidosis has become a treatable and curable condition with a combination of agents targeting multiple steps of the amyloid cascade. ICD implantation may not be as effective for the therapy of light chain (AL) cardiac amyloidosis as supposed earlier. In cases of unexpected and sudden death, autopsy may show unknown conditions and is valuable to assess existing risks for family members. Even after careful autopsy, a proportion of sudden deaths, ranging from 2 to 54%, remain unexplained and this broad range of values is likely due to the heterogeneity of autopsy protocols. Post mortem diagnosis of cardiac amyloidosis still represents a challenge for forensic pathologists. Detailed morphologic study of the heart and a complete histopathologic study are mandatory. Immunohistochemistry is essential for amyloid subclassification. A review of existing literature is performed by the authors and a methodological approach in post mortem diagnosis of light chain AL cardiac amyloidosis is proposed. Both macroscopic and microscopic findings are discussed

    Carbon nitride thin films as all-in-one technology for photocatalysis

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    Organic π-conjugated polymers are promising heterogeneous photocatalysts that involve photoredox or energy transfer processes. In such settings, the materials are usually applied in the form of dis..

    Two-dimensional Mixture of Dipolar Fermions: Equation of State and Magnetic Phases

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    We study a two-component mixture of fermionic dipoles in two dimensions at zero temperature, interacting via a purely repulsive 1/r31/r^3 potential. This model can be realized with ultracold atoms or molecules, when their dipole moments are aligned in the confinement direction orthogonal to the plane. We characterize the unpolarized mixture by means of the Diffusion Monte Carlo technique. Computing the equation of state, we identify the regime of validity for a mean-field theory based on a low-density expansion and compare our results with the hard-disk model of repulsive fermions. At high density, we address the possibility of itinerant ferromagnetism, namely whether the ground state can be fully polarized in the fluid phase. Within the fixed-node approximation, we show that the accuracy of Jastrow-Slater trial wave functions, even with the typical two-body backflow correction, is not sufficient to resolve the relevant energy differences. By making use of the iterative-backflow improved trial wave functions, we observe no signature of a fully-polarized ground state up to the freezing density.Comment: 12 pages, 6 figure

    Two-dimensional Mixture of Dipolar Fermions: Equation of State and Magnetic Phases

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    We study a two-component mixture of fermionic dipoles in two dimensions at zero temperature, interacting via a purely repulsive 1/r31/r^3 potential. This model can be realized with ultracold atoms or molecules, when their dipole moments are aligned in the confinement direction orthogonal to the plane. We characterize the unpolarized mixture by means of the Diffusion Monte Carlo technique. Computing the equation of state, we identify the regime of validity for a mean-field theory based on a low-density expansion and compare our results with the hard-disk model of repulsive fermions. At high density, we address the possibility of itinerant ferromagnetism, namely whether the ground state can be fully polarized in the fluid phase. Within the fixed-node approximation, we show that the accuracy of Jastrow-Slater trial wave functions, even with the typical two-body backflow correction, is not sufficient to resolve the relevant energy differences. By making use of the iterative-backflow improved trial wave functions, we observe no signature of a fully-polarized ground state up to the freezing density.Comment: 12 pages, 6 figure

    Emerging Role of Cellular Prion Protein in the Maintenance and Expansion of Glioma Stem Cells

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    Cellular prion protein (PrPC) is a membrane-anchored glycoprotein representing the physiological counterpart of PrP scrapie (PrPSc), which plays a pathogenetic role in prion diseases. Relatively little information is however available about physiological role of PrPC. Although PrPC ablation in mice does not induce lethal phenotypes, impairment of neuronal and bone marrow plasticity was reported in embryos and adult animals. In neurons, PrPC stimulates neurite growth, prevents oxidative stress-dependent cell death, and favors antiapoptotic signaling. However, PrPC activity is not restricted to post-mitotic neurons, but promotes cell proliferation and migration during embryogenesis and tissue regeneration in adult. PrPC acts as scaold to stabilize the binding between dierent membrane receptors, growth factors, and basement proteins, contributing to tumorigenesis. Indeed, ablation of PrPC expression reduces cancer cell proliferation and migration and restores cell sensitivity to chemotherapy. Conversely, PrPC overexpression in cancer stem cells (CSCs) from dierent tumors, including gliomas\u2014the most malignant brain tumors\u2014is predictive for poor prognosis, and correlates with relapses. The mechanisms of the PrPC role in tumorigenesis and its molecular partners in this activity are the topic of the present review, with a particular focus on PrPC contribution to glioma CSCs multipotency, invasiveness, and tumorigenicity

    Brugada syndrome and job fitness: report of three cases

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    Summary Introduction. Brugada syndrome is an inherited arrhythmogenic disorder predisposing patients to a high risk of sudden cardiac death. Specific guidelines on the health surveillance of affected workers are lacking. Objective. By presenting three illustrative cases, we propose an interdisciplinary approach for the clinical and functional evaluation of Brugada syndrome workers, aimed at continuing the occupational activity, by formulating appropriate prescriptions and limitations. Materials and methods. The subjects were investigated with an interdisciplinary protocol including 24-hour Holter electrocardiography with modified precordial leads, pharmacological test with ajmaline, molecular genetic analysis, electrophysiological study with ventricular stimulation, risk stratification, and occupational medicine evaluation. Results. The first case is a female 42 year-old company manager with positive ajmaline test and CACNA1C gene mutation (judged fit for the job with limitations regarding work-related stress); the second is a male 44 year-old welder with positive ajmaline test, SCN5A gene mutation, and associated OSAS (obstructive sleep apnea syndrome), who was advised to refrain from night shifts and driving company vehicles; the third subject is a male 45 year-old electrical technician with inducible ventricular tachyarrhythmia, who was implanted with a biventricular cardioverter defibrillator, and therefore recommended to avoid exposure to electromagnetic fields and working at heights. Conclusion. Patients with Brugada syndrome may come to the attention of the occupational physician. In this circumstance, the collaboration with an expert cardiologist allows to define the functional capabilities and the arrhythmogenic risk, and to formulate the judgment for job fitness
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