Gauge theory renormalizations from the open bosonic string

We present a unified point of view on the different methods available in the literature to extract gauge theory renormalization constants from the low-energy limit of string theory. The Bern-Kosower method, based on an off-shell continuation of string theory amplitudes, and the construction of low-energy string theory effective actions for gauge particles, can both be understood in terms of strings interacting with background gauge fields, and thus reproduce, in the low-energy limit, the field theory results of the background field method. We present in particular a consistent off-shell continuation of the one-loop gluon amplitudes in the open bosonic string that reproduces exactly the results of the background field method in the Feynman gauge.Comment: 14 pages, latex, no figure

Deep spectroscopy in nearby galaxy clusters: III Orbital structure of galaxies in Abell 85

Galaxies in clusters are strongly affected by their environment. They evolve according to several physical mechanisms that are active in clusters. Their efficiency can strongly depend on the orbital configuration of the galaxies. Our aim is to analyse the orbits of the galaxies in the cluster Abell 85, based on the study of the galaxy velocity anisotropy parameter. We have solved the Jeans equation under the assumption that the galaxies in A85 are collisionless objects, within the spherically symmetric gravitational potential of the virialized cluster. The mass of the cluster was estimated with X-ray and caustic analyses. We find that the anisotropy profile of the full galaxy population in A85 is an increasing monotonic function of the distance from the cluster centre: on average, galaxies in the central region (r/r200 < 0.3) are on isotropic orbits, while galaxies in the outer regions are on radial orbits. We also find that the orbital properties of the galaxies strongly depend on their stellar colour. In particular, blue galaxies are on less radial orbits than red galaxies. The different families of cluster galaxies considered here have the pseudo phase-space density profiles Q(r) and Qr(r) consistent with the profiles expected in virialized dark matter halos in $N$-body simulations. This result suggests that the galaxies in A85 have reached dynamical equilibrium within the cluster potential. Our results indicate that the origin of the blue and red colour of the different galaxy populations is the different orbital shape rather than the accretion time.Comment: 15 pages, 15 figures. Accepted for publication at MNRA

Practical Bayesian Modeling and Inference for Massive Spatial Datasets On Modest Computing Environments

With continued advances in Geographic Information Systems and related computational technologies, statisticians are often required to analyze very large spatial datasets. This has generated substantial interest over the last decade, already too vast to be summarized here, in scalable methodologies for analyzing large spatial datasets. Scalable spatial process models have been found especially attractive due to their richness and flexibility and, particularly so in the Bayesian paradigm, due to their presence in hierarchical model settings. However, the vast majority of research articles present in this domain have been geared toward innovative theory or more complex model development. Very limited attention has been accorded to approaches for easily implementable scalable hierarchical models for the practicing scientist or spatial analyst. This article is submitted to the Practice section of the journal with the aim of developing massively scalable Bayesian approaches that can rapidly deliver Bayesian inference on spatial process that are practically indistinguishable from inference obtained using more expensive alternatives. A key emphasis is on implementation within very standard (modest) computing environments (e.g., a standard desktop or laptop) using easily available statistical software packages without requiring message-parsing interfaces or parallel programming paradigms. Key insights are offered regarding assumptions and approximations concerning practical efficiency.Comment: 20 pages, 4 figures, 2 table

Comments on Supersymmetric Vector and Matrix Models

Some results in random matrices are generalized to supermatrices, in particular supermatrix integration is reduced to an integration over the eigenvalues and the resulting volume element is shown to be equivalent to a one dimensional Coulomb gas of both positive and negative charges.It is shown that,for polynomial potentials, after removing the instability due to the annihilation of opposite charges, supermatrix models are indistinguishable from ordinary matrix models, in agreement with a recent result by Alvarez-Gaume and Manes. It is pointed out however that this may not be true for more general potentials such as for instance the supersymmetric generalization of the Penner model.Comment: 6 page

A numerical study of interactions and stellar bars

For several decades it has been known that stellar bars in disc galaxies can be triggered by interactions, or by internal processes such as dynamical instabilities. In this work, we explore the differences between these two mechanisms using numerical simulations. We perform two groups of simulations based on isolated galaxies, one group in which a bar develops naturally, and another group in which the bar could not develop in isolation. The rest of the simulations recreate 1:1 coplanar fly-by interactions computed with the impulse approximation. The orbits we use for the interactions represent the fly-bys in groups or clusters of different masses accordingly to the velocity of the encounter. In the analysis we focus on bars' amplitude, size, pattern speed and their rotation parameter, ${\cal R}=R_{CR}/R_{bar}$. The latter is used to define fast (${\cal R}1.4$). Compared with equivalent isolated galaxies we find that bars affected or triggered by interactions: (i) remain in the slow regime for longer; (ii) are more boxy in face-on views; (iii) they host kinematically hotter discs. Within this set of simulations we do not see strong differences between retrograde or prograde fly-bys. We also show that slow interactions can trigger bar formation.Comment: 12 pages, 7 figures. Accepted for publication in MNRA

Descriptive epidemiology of vulvar and vaginal cancers in Vaud, Switzerland, 1974-1994

Background: To analyse trends in incidence, survival and risk of second neoplasms following vaginal and vulvar cancers using data collected by the Swiss Cancer Registry of Vaud over the 21-year period 1974-1994. Materials and methods: Subjects were 257 vulvo-vaginal cancers. Of these, 69 were vaginal, 153 vulvar cancers, and 35 non-specified lower genital tract neoplasms; 94 in situ neoplasms were also registered (85 for the vulva). Results: Invasive vaginal cancer incidence decreased from 0.8 in 1974-1984 to 0.4/100,000 women in 1985-1994, while invasive vulvar cancer incidence remained approximately stable around 1.2/100,000 (world standard); incidence of in situ vulvar cancer increased from 0.8 to 1.3/100,000, the rise being larger in younger women. Significant excesses for second primary neoplasms were observed for oro-pharyngeal and lung cancer, and for non-melanomatous skin neoplasms, as well as for invasive vulvar cancers following in situ cancers. Conclusions: This population-based dataset confirms that the incidence of in situ vulvar (but not invasive vulvar or vaginal cancer) has been increasing over the last 20 years. The excess second primary neoplasms supports the hypotheses that human papillomavirus and cigarette smoking are related to vulvo-vaginal neoplasm

Two-loop Yang-Mills diagrams from superstring amplitudes

Starting from the superstring amplitude describing interactions among D-branes with a constant world-volume field strength, we present a detailed analysis of how the open string degeneration limits reproduce the corresponding field theory Feynman diagrams. A key ingredient in the string construction is represented by the twisted (Prym) super differentials, as their periods encode the information about the background field. We provide an efficient method to calculate perturbatively the determinant of the twisted period matrix in terms of sets of super-moduli appropriate to the degeneration limits. Using this result we show that there is a precise one-to-one correspondence between the degeneration of different factors in the superstring amplitudes and one-particle irreducible Feynman diagrams capturing the gauge theory effective action at the two-loop level.Comment: 42 pages plus appendices, 10 figure

Dietary approach to stop hypertension (DASH) diet and associated socioeconomic inequalities in the United Kingdom

The dietary approach to stop hypertension (DASH) diet is an effective measure in the prevention and treatment of CVD. We evaluated recent trends in socioeconomic differences in the DASH score in the UK population, using education, occupation and income as proxies of socioeconomic position (SEP). We analyzed data on 6416 subjects aged 18 and older collected in the National Diet and Nutrition Survey (NDNS 2008-2016). The DASH score was calculated using sex-specific quintiles of DASH items. Multiple linear regression and quantile regression models were used to evaluate the trend in DASH score according to SEP. The mean DASH score was 24 (standard deviation: 5). The estimated mean differences between people with no qualification and those having the highest level of education was -3.61 points (95% CI: -4.00; -3.22). The mean difference between subjects engaged in routine occupations and those engaged in high managerial and professional occupations was -3.41 points (95% CI: -3.89; -2.93) and for those in the first fifth and last fifth of the household income distribution was -2.71 points (95% CI: -3.15; -2.28). DASH score improved over time and no significant differences in the trend were observed across SEP. The widest socioeconomic differences emerged for consumption of fruit, vegetables, wholegrains, nuts, seeds and legumes. Despite an overall increase in the DASH score, a persisting SEP gap was observed. This is an important limiting factor in reducing the high socioeconomic inequality in CVD observed in the UK

Effects of curing on the hydro-mechanical behaviour of cement-bentonite mixtures for cut-off walls

Cement-bentonite cut-off walls are commonly employed in geoenvironmental applications to limit ground water flow and pollutant transport. The wide diffusion of this artificial material in the current practice is not only due to its low permeability, but also to its simplicity of use. In this paper, experimental evidences about the role of curing on the hydro-mechanical behaviour of cement-bentonite mixtures are presented. Different curing times and curing conditions (representative for either water saturated or hydrocarbon polluted soils) have been considered, and their effects on both hydraulic conductivity and mechanical response in oedometer and triaxial conditions have been assessed. A unified hydro-mechanical framework, accounting for the changes of material fabric occurring with curing time and environment, is formulated. The hydraulic conductivity is very well predicted by a Kozeny-Carman like equation, whereas the mechanical behaviour is finely reproduced via an enhanced elastic–plastic constitutive model