The weak Frenet frame of non-smooth curves with finite total curvature and absolute torsion

We deal with a notion of weak binormal and weak principal normal for non-smooth curves of the Euclidean space with finite total curvature and total absolute torsion. By means of piecewise linear methods, we first introduce the analogous notation for polygonal curves, where the polarity property is exploited, and then make use of a density argument. Both our weak binormal and normal are rectifiable curves which naturally live in the projective plane. In particular, the length of the weak binormal agrees with the total absolute torsion of the given curve. Moreover, the weak normal is the vector product of suitable parameterizations of the tangent indicatrix and of the weak binormal. In the case of smooth curves with positive curvature, the weak binormal and normal yield (up to a lifting) the classical notions of binormal and normal.Comment: 18 pages, 2 figure

Bounded variation and relaxed curvature of surfaces

We consider a relaxed notion of energy of non-parametric codimension one surfaces that takes account of area, mean curvature, and Gauss curvature. It is given by the best value obtained by approximation with inscribed polyhedral surfaces. The BV and measure properties of functions with finite relaxed energy are studied. Concerning the total mean and Gauss curvature, the classical counterexample by Schwarz-Peano to the definition of area is also analyzed.Comment: 25 page

Properly pricing country risk: a model for pricing long-term fundamental risk applied to central and eastern European countries

The private sector has used proxies such as sovereign credit ratings, spreads on sovereign bonds and spreads on sovereign credit default swaps (CDS) to gauge country risk, even though these measures are pricing the risk of default of government bonds, which is different from the risks facing private participants in cross-border financing. Under normal market conditions, the CDS spreads are a very useful source of information on country risk. However, the recent crisis has shown that the CDS spreads might lead to some underpricing or overpricing of fundamentals in the case of excessively low or excessively high risk aversion. In this paper we develop an alternative measure of country risk that extracts the volatile, short-term market sentiment component from the sover eign CDS spread in order to improve its reliability in periods of market distress. We show that adverse market sentiment was a key driver of the sharp increase in sovereign CDS spreads of central and eastern European (CEE) countries during the most severe phase of the crisis. We also show that our measure of country risk sheds some light on the observed stability of cross-border bank flows to CEE banks during the crisis.country risk, credit default swaps, credit ratings, cross-border flows, financial crisis, central and eastern Europe, foreign-owned banks

SINTESI DI IBRIDI DUALI ANTICOLINESTERASICI E H2S DONATORI PER IL TRATTAMENTO DEL MORBO D'ALZHEIMER

La malattia di Alzheimer (AD) è un disordine neurodegenerativo progressivo, incurabile, che rappresenta la più comune forma di demenza nelle persone anziane. Le cause neuropatologiche non sono tuttora completamente note, tuttavia sono stati identificati numerosi fattori quali l’aggregazione beta-amiloide, con formazione di grovigli neurofibrillari, alterati livelli di acetilcolina, stress ossidativo e disomeostasi di ioni metallici che rivestono un ruolo chiave nella patogenesi. Alla luce delle insoddisfacenti terapie ad oggi in uso in questa tesi di laurea sono state sintetizzate molecole ibride combinando una porzione anticolinesterasica con porzioni capaci di rilasciare in vivo H2S

Tissue metabolomics and HR-MAS NMR

High-Resolution Magic Angle Spinning (HR-MAS) Nuclear Magnetic Resonance (NMR) can play an important role among the analytical methods that can be used in metabolomics. It was developed more than 25 years ago,[1] and since then it has been used to analyze cells and biological tissues in many fields: biochemical, biomedical,[2] plants,[3] agriculture,[4] food,[5] etc. Typical problems tackled are information on cellular metabolisms of physiological and pathological processes, response to some kind of stress, differences among cultivars or varieties, metabolism in little living organisms. HR-MAS NMR has become an important platform for metabolomic studies. The technique allows the detection of the metabolic profile directly on intact tissue samples and cells, producing NMR spectra with resolution that can be comparable to that obtained from sample extract solutions, avoiding complex metabolite extraction processes, and preserving tissue and cellular structures. These studies can be based on the analysis of metabolic profiles in their entirety or on the quantification of individual metabolites or metabolite ratios. The basis of the technique, some critical issues and some examples of application in different contexts will be shown. [1] L. L. Cheng, C. L. Lean, A. Bogdanova, S. C. Wright, Jr, J. L. Ackerman, T. J. Brady, L. Garrido, Magnetic resonance in medicine (1996), 36, 653-8 [2] L. L Cheng, NMR in biomedicine (2023), 36, e4684. [3] C. Deborde, A. Moing, L. Roch, D. Jacob, D. Rolin, P. Giraudeau, Progress in Nuclear Magnetic Resonance Spectroscopy (2017), 102-103, 61-97. [4] P. Mazzei, A. Piccolo, Chemical and Biological Technologies in Agriculture (2017), 4, 11/1-11/13. [5] C. Corsaro, N. Cicero, D. Mallamace, S. Vasi, C. Naccari, A. Salvo, S. V. Giofre, G. Dugo, Food Research International (2016), 89(Part_3), 1085-1094

Computational Fluid Dynamics analysis of heat transfer problems in heated channels with water at supercritical pressure

The present work, partly made during a three month stage at the University of Aberdeen (UK), is aimed to investigate the heat transfer problem in heated channels with water at supercritical pressure. The analysis is performed with three different Computational Fluid Dynamics codes (SWIRL, an “in-house” CFD code, FLUENT and STAR-CCM+, general-purpose CFD codes). The aim of this work is to evaluate the performances of different low-Reynolds number turbulence models in predicting mixed convection heat transfer of fluids at supercritical pressure, with particular attention to the features that are affected by the modifications of the turbulence field due to influence of flow acceleration and buoyancy. Several simulations are performed and the predicted results are compared with the data obtained by the experimental facility in the Nuclear Engineering Laboratory at the University of Manchester. The simulated test section is 2 m long, with a diameter of 25.4 mm (1”). Different operating conditions are imposed for water at 25 MPa, in both downward and upward flow. Mainly, the analysis is conducted using the Yang-Shih turbulence model and the SWIRL CFD code in simple two-dimensional geometry. Results on a broad-spectrum of boundary conditions are achieved and a better understanding of the heat transfer behaviour was developed by the analysis of the dimensionless velocity and the dimensionless turbulent kinetic energy, for different axial locations along the pipe. Deterioration and enhancement phenomena are pointed out considering the ratio between the Nusselt number in the mixed convection flow and the Nusselt number of forced flow, while the difference between the effects of buoyancy and flow acceleration is pointed out by the Buoyancy parameter Bo*, introduced by Jackson, et al. (1979). Some numerical aspects are also pointed out. The low-Reynolds number k-e turbulence models adopted in the work, are generally able to predict both heat transfer enhancement and deterioration phenomena even if, in some upward flow cases, wall temperature over prediction was obtained from the simulations, due to the large change in fluid properties when temperature reaches the pseudocritical value. So, the predicted effect of buoyancy is much greater than suggested by a buoyancy parameter based on bulk temperature. Buoyancy and the consequent laminarization effects mainly govern the occurrence of deterioration in the considered experimental data, but other mechanisms contribute to the occurrence of this phenomenon

The Motivation to Write Profile-College: A Tool to Assess the Writing Motivation of Teacher Candidates

Writing is an important aspect of literacy regardless of the grade or discipline. State standards have defined the writing genres, crafts, and skills that are to be taught by teachers in PK-12 classrooms. However, in addition to standards, research indicates that a teacher’s own conception of writing is crucial to establishing classroom conditions necessary for young writers to grow, explore and take risks. If this is the job of PK-12 educators, then it is essential for higher education instructors to understand and explore the writing conceptions of teacher candidates. One of these critical conceptions is the motivation to write. The Motivation to Write Profile-College (MWP-C) was designed and validated to assess the writing motivation of teacher candidates. The profile can inform the important conversations necessary to ensure that teacher candidates are fully prepared to teach writing as motivated writers themselves

The trans-sialidase from Trypanosoma cruzi induces thrombocytopenia during acute Chagas' disease by reducing the platelet sialic acid contents

Strong thrombocytopenia is observed during acute infection with Trypanosoma cruzi, the parasitic protozoan agent of American trypanosomiasis or Chagas' disease. The parasite sheds trans-sialidase, an enzyme able to mobilize the sialyl residues on cell surfaces, which is distributed in blood and is a virulence factor. Since the sialic acid content on the platelet surface is crucial for determining the half-life of platelets in blood, we examined the possible involvement of the parasite-derived enzyme in thrombocytopenia induction. We found that a single intravenous injection of trans-sialidase into naïve mice reduced the platelet count by 50%, a transient effect that lasted as long as the enzyme remained in the blood. CD43(−/−) mice were affected to a similar extent. When green fluorescent protein-expressing platelets were treated in vitro with trans-sialidase, their sialic acid content was reduced together with their life span, as determined after transfusion into naïve animals. No apparent deleterious effect on the bone marrow was observed. A central role for Kupffer cells in the clearance of trans-sialidase-altered platelets was revealed after phagocyte depletion by administration of clodronate-containing liposomes and splenectomy. Consistent with this, parasite strains known to exhibit more trans-sialidase activity induced heavier thrombocytopenia. Finally, the passive transfer of a trans-sialidase-neutralizing monoclonal antibody to infected animals prevented the clearance of transfused platelets. Results reported here strongly support the hypothesis that the trans-sialidase is the virulence factor that, after depleting the sialic acid content of platelets, induces the accelerated clearance of the platelets that leads to the thrombocytopenia observed during acute Chagas' disease

A second large plasmid encodes conjugative transfer and antimicrobial resistance in O119:H2 and some typical O111 enteropathogenic \u3ci\u3eEscherichia coli\u3c/i\u3e strains

A novel and functional conjugative transfer system identified in O119:H2 enteropathogenic Escherichia coli (EPEC) strain MB80 by subtractive hybridization is encoded on a large multidrug resistance plasmid, distinct from the well-described EPEC adherence factor (EAF) plasmid. Variants of the MB80 conjugative resistance plasmid were identified in other EPEC strains, including the prototypical O111:NM strain B171, from which the EAF plasmid has been sequenced. This separate large plasmid and the selective advantage that it confers in the antibiotic era have been overlooked because it comigrates with the virulence plasmid on conventional gels