Vacuum local and global electromagnetic self-energies for a point-like and an extended field source

We consider the electric and magnetic energy densities (or equivalently field fluctuations) in the space around a point-like field source in its ground state, after having subtracted the spatially uniform zero-point energy terms, and discuss the problem of their singular behavior at the source's position. We show that the assumption of a point-like source leads, for a simple Hamiltonian model of the interaction of the source with the electromagnetic radiation field, to a divergence of the renormalized electric and magnetic energy density at the position of the source. We analyze in detail the mathematical structure of such singularity in terms of a delta function and its derivatives. We also show that an appropriate consideration of these singular terms solves an apparent inconsistency between the total field energy and the space integral of its density. Thus the finite field energy stored in these singular terms gives an important contribution to the self-energy of the source. We then consider the case of an extended source, smeared out over a finite volume and described by an appropriate form factor. We show that in this case all divergences in local quantities such as the electric and the magnetic energy density, as well as any inconsistency between global and space-integrated local self-energies, disappear.Comment: 8 pages. The final publication is available at link.springer.co

Composition of bird nests is a species-specific characteristic

Bird nests represent an extended phenotype of individuals expressed during reproduction and so exhibit variability in composition, structure and function. Descriptions of nests based on qualitative observations suggest that there is interspecific variation in size and composition but there are very few species in which this has been confirmed. For these species, data of the amounts of different materials indicate that nest construction behaviour is plastic and affected by a variety of factors, such as prevailing temperature, geographic location, and availability of materials. The lack of data on nest composition is hampering our understanding of how nests achieve their various functions and how different species solve the problem of building a nest that will accommodate incubation and allow successful hatching of eggs. This study deconstructed nests of four species of the Turdidae, four species of the Muscicapidae, and six species of the Fringillidae and quantified the size of the nests and their composition. These data were used to test: (1) whether nest size correlated with adult bird mass; (2) whether it was possible to distinguish between species on the basis of their nest composition; and (3) whether, within a species, it was possible to distinguish between the cup lining and the rest of the nest based on composition. Most but not all nest dimensions correlated with bird mass. Principal component analysis revealed species differences based on nest composition and discriminant analysis could distinguish cup lining from the outer nest based on material composition. Intraspecific variation in composition varied among species and in general fewer types of material were found in the cup lining than the outer nest. These data provide insight into how nests are constructed by the different species and in conjunction with studies of the mechanical, thermal and hydrological properties of a nest, will begin to reveal how and why individual species select particular combinations of materials to build a nest

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

Prospective associations of coronary heart disease loci in African Americans using the MetaboChip

Background: Coronary heart disease (CHD) is a leading cause of morbidity and mortality in African Americans. However, there is a paucity of studies assessing genetic determinants of CHD in African Americans. We examined the association of publishe

Immune status of high-risk smoldering multiple myeloma patients and its therapeutic modulation under LenDex: a longitudinal analysis

Persistence of chemoresistant minimal residual disease (MRD) plasma cells (PCs) is associated with inferior survival in multiple myeloma (MM). Thus, characterization of the minor MRD subclone may represent a unique model to understand chemoresistance, but to our knowledge, the phenotypic and genetic features of the MRD subclone have never been investigated. Here, we compared the antigenic profile of MRD vs diagnostic clonal PCs in 40 elderly MM patients enrolled in the GEM2010MAS65 study and showed that the MRD subclone is enriched in cells overexpressing integrins (CD11a/CD11c/CD29/CD49d/CD49e), chemokine receptors (CXCR4), and adhesion molecules (CD44/CD54). Genetic profiling of MRD vs diagnostic PCs was performed in 12 patients; 3 of them showed identical copy number alterations (CNAs), in another 3 cases, MRD clonal PCs displayed all genetic alterations detected at diagnosis plus additional CNAs that emerged at the MRD stage, whereas in the remaining 6 patients, there were CNAs present at diagnosis that were undetectable in MRD clonal PCs, but also a selected number of genetic alterations that became apparent only at the MRD stage. The MRD subclone showed significant downregulation of genes related to protein processing in endoplasmic reticulum, as well as novel deregulated genes such as ALCAM that is prognostically relevant in MM and may identify chemoresistant PCs in vitro. Altogether, our results suggest that therapy-induced clonal selection could be already present at the MRD stage, where chemoresistant PCs show a singular phenotypic signature that may result from the persistence of clones with different genetic and gene expression profiles. This trial was registered at www.clinicaltrials.gov as #NCT01237249