The Physical Propagator of a Slowly Moving Charge

We consider an electron which is electromagnetically dressed in such a way that it is both gauge invariant and that it has the associated electric and magnetic fields expected of a moving charge. We study the propagator of this dressed electron and, for small velocities, show explicitly at one loop that at the natural (on-shell) renormalisation point, $p_0=m$, ${\bold p}= m{\bold v}$, one can renormalise the propagator multiplicatively. Furthermore the renormalisation constants are infra-red finite. This shows that the dressing we use corresponds to a slowly moving, physical asymptotic field.Comment: 10 pages, plain TeX, 1 Figure (uuencoded needs epsfig.sty

Charges from Dressed Matter: Construction

There is a widespread belief in particle physics that there is no relativistic description of a charged particle. This is claimed to be due to persistent, long range interactions which distort the in and out going plane waves and generate infra-red divergences. In this paper we will show that this is not the case in QED. We construct locally gauge invariant charged fields which do create in and out Fock states. In a companion paper we demonstrate that the Green's functions of these fields have a good pole structure describing particle propagation.Comment: 29 pages, LaTeX, 2 figures, two new references, minor changes, version to appear in Annals of Physic

Challenging homophobic bullying in schools: the politics of progress

In recent years homophobic bullying has received increased attention from NGOs, academics and government sources and concern about the issue crosses traditional moral and political divisions. This article examines this ‘progressive’ development and identifies the ‘conditions of possibility’ that have enabled the issue to become a harm that can be spoken of. In doing so it questions whether the readiness to speak about the issue represents the opposite to prohibitions on speech (such as the notorious Section 28) or whether it is based on more subtle forms of governance. It argues that homophobic bullying is heard through three key discourses (‘child abuse’, ‘the child victim’ and ‘the tragic gay’) and that, while enabling an acknowledgement of certain harms, they simultaneously silence other needs and experiences. It then moves to explore the aspirational and ‘liberatory’ political investments that underlie these seemingly ‘common-sense’ descriptive discourses and concludes with a critique of the quasi-criminal responses that the dominant political agenda of homophobic bullying gives rise to. The article draws on, and endeavours to develop a conversation between, critical engagements with the contemporary politics of both childhood and sexuality

Density estimation with Gaussian processes for gravitational-wave posteriors

The properties of black-hole and neutron-star binaries are extracted from gravitational-wave signals using Bayesian inference. This involves evaluating a multi-dimensional posterior probability function with stochastic sampling. The marginal probability density distributions from which the samples are drawn are usually interpolated with kernel density estimators. Since most post-processing analysis within the field is based on these parameter estimation products, interpolation accuracy of the marginals is essential. In this work, we propose a new method combining histograms and Gaussian Processes as an alternative technique to fit arbitrary combinations of samples from the source parameters. This method comes with several advantages such as flexible interpolation of non-Gaussian correlations, Bayesian estimate of uncertainty, and efficient re-sampling with Hamiltonian Monte Carlo

Il futuro non (è) scritto

Review of Recensione diCuratori: Paolo Carlotti, Anna Irene Del Monaco, Dina NenciniTitolo: L’ampliamento della Camera dei Deputati. Letture e prospettive per il progetto. Collana: Lettura e progetto. Nuova Serie FrancoAngeliLingua: italiano Editore: FrancoAngeliCaratteristiche: formato 14x21,5 cm, brossura, b/nISBN: 9788891751027Anno: 201

Degraded Paper: Stabilization and Strengthening Through Nanocellulose Application

Cellulose nanomaterials are a promising material for the stabilization of degraded paper, since their characteristics in composition, structure and physical properties are close to those of cellulose. Two types of nanocellulose were tested regarding their performance in stabilizing fragile papers: cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC). The suspensions were applied to a pure cellulose paper and historical newspaper. The study included optical and microscopic characterization, determination of pH, conductivity, and rheology as well as measurement of changes in tensile strength after treatment. The results showed that the pH, as well as the optical and haptic properties, were not altered after treatment. A 50% increase in paper’s tensile strength is achieved with 3% CNC applied on the paper. In addition, fluorescence microscopy demonstrated that, due to their nanoscale dimension, the suspensions can reinforce the surface but also fully penetrate the paper matrix achieving therefore an overall stabilization.Cellulose Nanomaterialien sind ein vielversprechendes Material für die Stabilisierung von degradiertem Papier, da sie in Zusammensetzung und Struktur der Cellulose ähnlich sind. Cellulose Nanofibrillen und Cellulose Nanokristalle wurden in Hinblick auf ihre Fähigkeit zur Stabilisierung von fragilen Papieren getestet. Die Suspensionen wurden auf Filterpapier und historisches Zeitungspapier aufgebracht. Die Charakterisierung der Proben beinhaltete optische und mikroskopische Veränderungen, Messung der Zugfestigkeit und Bestimmung des pH-Werts. Die optischen und haptischen Veränderungen der Papierproben durch die Behandlung waren minimal, der pH-Wert wurde nicht negativ verändert. Die Papierfestigkeit wurde – bei einem Auftrag von 3 wt% Nanokristallen – um 50% erhöht. Mittels Fluoreszenzmikroskopie konnte gezeigt werden, dass die Suspensionen aufgrund ihrer Dimensionen im Nanobereich sowohl die Oberfläche verstärken als auch das Papierfasergefüge durchdringen und somit eine umfassende Festigung erzielen

Pedagogically Semi-Equivalent Repertoire Analogies: Soprano Fach

For decades, conservatories have divided singing into two tracks: classical (voce chiusa) or musical theater (CCM). Young singers are forced to decide which track they will continue on—seemingly for the rest of their careers. But the demand for a single skill set does not reflect today’s job market nor the vocal demands singers will face throughout their careers. Singers, instead, must be readily able to compete at high levels on more than one track. Yet the majority of programs have not restructured to accommodate this change. Such recalcitrance is detrimental to singers as they navigate high-stakes, high-pressure careers with little to no knowledge of crucial skills they may need. Often this can lead to over-singing, poor vocal health, and sometimes the end of a career. I propose a way in which both tracks—voce chiusa and CCM—can be used symbiotically. This combinatorial approach is good for future careers, but more importantly, it is beneficial to a singer’s intrinsic laryngeal muscle development. Finding a healthy belt for voce chiusa-trained singers is equally beneficial as finding a strong head-voice for CCM singers. This synthesis of vocal techniques actually yields a super-technique—a more flexible, healthy, and individualized sound that is unified through the use of the breath. This document is an exposition of the pedagogical benefits of learning both traditional, voce chiusa and CCM repertoire concurrently in vocal training. I also offer repertoire that supports this combinatorial approach in order to make its utility in the voice studio more accessible. This repertoire features pedagogically semi-equivalent song pairings with a focus on the soprano Fach. I will highlight the major areas of equivalence and pedagogical efficacy shared by the voce chiusa and CCM repertoire paired. Twenty-five style pairings are offered as a sample of the future catalog I hope to aggregate for all major voice types. The purpose of the catalog is to incorporate pluralistic style in the studio by combining the pedagogical methods of voce chiusa and CCM singing in order to train singers to have greater vocal development, flexibility, and health

Experimental and statistical investigations on atmospheric heavy metals concentrations in an industrial area of Southern Italy

In this paper we present experimental protocol and statistical proceduresfor evaluating atmospheric concentrationsof TSP and heavy metals(Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in the area of Tito Scalo (PZ, Southern Italy), a small industrial site, far from urban areas and surrounded by agricultural and naturalistic sites. In order to characterise the concentrations level and the temporal pattern of each pollutant, we have analysed data collected in two field surveys (April-December 1997, April-December 1998) with univariate and multivariate statistical methods. Furthermore we have investigated the relationships between pollutants concentrationsand meteoclimatic parameters(temp erature and rainfalls)

Analisi e gestione del rischio clinico e applicazione alle macchine della radioterapia

LAUREA MAGISTRAL

Los documentos medievales como fuentes para el estudio de las parroquias e iglesias gallegas: el distrito de Monte de Meda (Lugo)

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