Bosonization of World-Sheet Fermions in Minkowski Space-Time

We propose a way of bosonizing free world-sheet fermions for $4$-dimensional heterotic string theory formulated in Minkowski space-time. We discuss the differences as compared to the standard bosonization performed in Euclidean space-time.Comment: 1+9 pages, TeX macros include

On the Normalization and Hermiticity of Amplitudes in 4D Heterotic Superstrings

We consider how to normalize the scattering amplitudes of 4D heterotic superstrings in a Minkowski background. We fix the normalization of the vacuum amplitude (the string partition function) at each genus, and of every vertex operator describing a physical external string state in a way consistent with unitarity of the $S$-matrix. We also provide an explicit expression for the map relating the vertex operator of an incoming physical state to the vertex operator describing the same physical state, but outgoing. This map is related to hermitean conjugation and to the hermiticity properties of the scattering amplitudes.Comment: 1+33 pages, TeX with macros include

La filière étatique des semences de riz pluvial en Casamance (Sénégal) : fonctionnement, contraintes et perspectives de développement

Description du sujet. Dans les pays subsahariens et en particulier au Sénégal, les systèmes semenciers traditionnels représentent encore l'option la plus répandue dans l'agriculture familiale nonobstant les nombreux efforts des Etats pour développer des filières semencières modernes et économiquement durables. Objectifs. Analyser le secteur semencier formel du riz pluvial de la Casamance, une région à forte vocation rizicole où le riz représente toujours la première source alimentaire des ménages ruraux, aux niveaux organisationnel et de structuration du marché. Méthode. Les données statistiques collectées ont été élaborées pour décrire la situation de la demande/offre de semences certifiées de riz dans la sous-région et la région ciblée. A travers des entretiens semi-directifs, les acteurs principaux de la filière ont été interviewés pour identifier et analyser les maillons de la filière et combler le gap informatif venant des données quantitatives. Résultats. L'étude identifie les principales limites et contraintes ainsi que les inefficacités du système semencier formel conçu comme filière marchande mais non adapté à un contexte de subsistance où la demande commerciale finale de semences certifiées est presque nulle. Une forte dépendance des acteurs impliqués par rapport aux interventions de l'Etat et de ses partenaires techniques et financiers et le manque d'un cadre de concertation et de planification entre les différents acteurs de la chaîne semencière ont été relevés. Conclusions. La mise en oeuvre d’un système semencier intégré et d’un cadre d'actions à entreprendre pour soutenir l'intégration des différentes composantes de la filière sont proposés. Ce cadre peut être retenu comme une démarche d'orientation et d'aide à l’identification et à la hiérarchisation des interventions de l’Etat et de ses PTF. Description of the subject. In sub-Saharan countries and particularly in Senegal, traditional seed systems still represent the most widespread option in family-based agricultures, despite the many efforts made by Governments to develop modern and economically sustainable seed chains. Objectives. Analyse formal rainfed rice seed sector in Casamance, a rice-rich regionwhere rice is still the main source of food for rural households, at the organizational and at the level of market structure. Method. Collected statistical data were processed to describe the situation of demand/supply of certified rice seed in the subregion and in targeted region. Through semi-structured interviews, the main actors of the sector were interviewed to identify and analyse chain structure and to fill the information gap from quantitative data. Results. The study identifies the main limitations and constraints of the sector as well as the inefficiencies of a seed system designed as a market chain and not adapted to a subsistence context where the final commercial demand for certified seeds is almost zero. A strong dependence of the actors involved in relation to interventions of Government and its technical and financial partners and the lack of a consultation and planning framework between actors and supply systems have been outlined. Conclusions. The implementation of an integrated seed system and a framework of actions to be undertaken in the region to support the integration of various chain are proposed. This framework can be used as tool to orient and assist the identification and prioritization of interventions of Government and its TFP. &nbsp

On the computation of one-loop amplitudes with external fermions in 4d heterotic superstrings

We present the technical tools needed to compute any one-loop amplitude involving external spacetime fermions in a four-dimensional heterotic string model a` la Kawai-Lewellen-Tye. As an example, we compute the one-loop three-point amplitude with one "photon" and two external massive fermions ("electrons"). As a check of our computation, we verify that the one-loop contribution to the Anomalous Magnetic Moment vanishes if the model has spacetime supersymmetry, as required by the supersymmetric sum rules.Comment: 1+59 pages, TeX macros included (AMSFonts required

Second-order Post-Minkowskian scattering in arbitrary dimensions

We extract the long-range gravitational potential between two scalar particles with arbitrary masses from the two-to-two elastic scattering amplitude at 2nd Post-Minkowskian order in arbitrary dimensions. In contrast to the four-dimensional case, in higher dimensions the classical potential receives contributions from box topologies. Moreover, the kinematical relation between momentum and position on the classical trajectory contains a new term which is quadratic in the tree-level amplitude. A precise interplay between this new relation and the formula for the scattering angle ensures that the latter is still linear in the classical part of the scattering amplitude, to this order, matching an earlier calculation in the eikonal approach. We point out that both the eikonal exponentiation and the reality of the potential to 2nd post-Minkowskian order can be seen as a consequence of unitarity. We finally present closed-form expressions for the scattering angle given by leading-order gravitational potentials for dimensions ranging from four to ten.Comment: 51 pages, 1 figure, version to appear in JHE

The holographic QCD axion

A holographic model of QCD axion is presented. It describes a composite axion in the KSVZ class. Having a gravity dual, based on the Witten-Sakai-Sugimoto model, it is calculable in the strongly coupled regime. Its basic properties are derived, including the low energy Lagrangian, from which the axion couplings to nucleons can be derived. Basic features in the deconfined phase are studied as well. In particular, the temperature dependence of the axion mass is extracted from the topological susceptibility. As an aside, the topological susceptibility of strongly coupled N = 4 SYM at finite temperature is derived for the first time.Fil: Bigazzi, Francesco. Istituto Nazionale di Fisica Nucleare. Sezione di Firenze; ItaliaFil: Caddeo, Alessio. Istituto Nazionale di Fisica Nucleare. Sezione di Firenze; Italia. Università degli Studi di Firenze; ItaliaFil: Cotrone, Aldo L.. Istituto Nazionale di Fisica Nucleare. Sezione di Firenze; Italia. Università degli Studi di Firenze; ItaliaFil: Di Vecchia, Paolo. Universidad de Copenhagen; Dinamarca. Royal Institute of Technology; SueciaFil: Marzolla, Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Istituto Nazionale di Fisica Nucleare. Sezione di Firenze; Italia. Università degli Studi di Firenze; Itali

A multi-methodological protocol to characterize PDO olive oils

An analytical approach including Panel Test, Isotope Ratio Mass Spectrometry (IRMS) and Nuclear Magnetic Resonance (NMR) spectroscopy was proposed to characterize Italian “Colline Pontine” PDO olive oils (40 samples) of two consecutive crop years. Our approach has evidenced the high quality of these olive oils. Only 6 of 40 olive oils samples were defined as “defective” by the official Panel Test due to the detection of negative sensory attributes. The low variability of isotopic data monitored by IRMS confirmed that the olive oil samples all came from a limited geographical area. NMR spectra did not evidence any chemical composition anomaly in the investigated samples. In order to assess the influence of harvesting year over the olive oil chemical composition, the NMR analysis was extended to other 22 olive oil samples of a third harvesting year. NMR data were submitted to two different statistical methods, namely, analysis of variance (ANOVA) and principal component analysis (PCA) allowing olive oils of three consecutive harvesting years to be grouped

Trend of estimated glomerular flitration rate in a large cohort of HIV mother-to -child infected patients, an observational multicenter study from 2010 to 2018

Background: People vertically infected with HIV (PVI-HIV) are a special population, due to exposition since birth to HIV and antiretroviral therapy (ART). Among ART, Tenofovir disoproxil fumarate (TDF) was widely used in recent years, but there are few data on safety in these patients; in particular, data about estimated glomerular filtration rate (eGFR) trend in this population. Aim of our study is to evaluate eGFR trend in a multicentre cohort of PVI-HIV exposed to TDF

On the Compton Scattering in String Theory

We explicitly compute the Compton amplitude for the scattering of a photon and a (massless) ``electron/positron'' at tree level and one loop, in a four-dimensional fermionic heterotic string model. We comment on the relationship between the amplitudes we compute in string theory and the corresponding ones in field theory.Comment: 1+12 pages, LaTe