Spontaneous Emission in ultra-cold spin-polarised anisotropic Fermi Seas

We examine and explain the spatial emission patterns of ultracold excited fermions in anisotropic trapping potentials in the presence of a spin polarised Fermi sea of ground state atoms. Due to the Pauli principle, the Fermi sea modifies the available phase space for the recoiling atom and thereby modifies its decay rate and the probability of the emitted photon's direction. We show that the spatial anisotropies are due to an intricate interplay between Fermi energies and degeneracy values of specific energy levels and identify a regime in which the emission will become completely directional. Our results are relevant for recent advances in trapping and manipulating cold fermionic samples experimentally and give an example of a conceptually new idea for a directional photon source.Comment: 7 pages, 7 figure

A deep Chandra observation of the poor cluster AWM4 - II. The role of the radio jets in enriching the intra-cluster medium

We use a Chandra observation of the poor cluster AWM4 to map the temperature and abundance of the intra-cluster medium, so as to examine the influence of the central radio galaxy on its environment. While the cluster core is generally enriched to near-solar abundances, we find evidence of super-solar abundances correlated with the radio jets, extending ~35 kpc from the core of the central dominant galaxy NGC 6051 along its minor axis. We conclude that the enriched gas has been transported out of the central galaxy through the action of the radio source. We estimate the excess mass of iron in the entrained gas to be ~1.4x10^6 Msol, and find that this can be produced in the core of NGC 6051 within the timescale of the AGN outburst. The energy required to transport this gas to its current location is ~4.5x10^57 erg, a significant fraction of the estimated total mechanical energy output of the AGN, though this estimate is dependent on the degree of enrichment of the uplifted gas. The larger near-solar abundance region is also compatible with enrichment by metals mixed outward from NGC 6051 over a much longer timescale.Comment: Accepted for publication in MNRAS, 11 pages, 6 figure

De novo identification of complex traits associated with asthma

IntroductionAsthma is a heterogeneous inflammatory disease often associated with other complex phenotypes. Identifying asthma-associated diseases and uncovering the molecular mechanisms mediating their interaction can help detangle the heterogeneity of asthma. Network analysis is a powerful approach for untangling such inter-disease relationships.MethodsHere, we integrated information on physical contacts between common single nucleotide polymorphisms (SNPs) and gene expression with expression quantitative trait loci (eQTL) data from the lung and whole blood to construct two tissue-specific spatial gene regulatory networks (GRN). We then located the asthma GRN (level 0) within each tissue-specific GRN by identifying the genes that are functionally affected by asthma-associated spatial eQTLs. Curated protein interaction partners were subsequently identified up to four edges or levels away from the asthma GRN. The eQTLs spatially regulating genes on levels 0–4 were queried against the GWAS Catalog to identify the traits enriched (hypergeometric test; FDR ≤ 0.05) in each level.ResultsWe identified 80 and 82 traits significantly enriched in the lung and blood GRNs, respectively. All identified traits were previously reported to be comorbid or associated (positively or negatively) with asthma (e.g., depressive symptoms and lung cancer), except 8 traits whose association with asthma is yet to be confirmed (e.g., reticulocyte count). Our analysis additionally pinpoints the variants and genes that link asthma to the identified asthma-associated traits, a subset of which was replicated in a comorbidity analysis using health records of 26,781 asthma patients in New Zealand.DiscussionOur discovery approach identifies enriched traits in the regulatory space proximal to asthma, in the tissue of interest, without a priori selection of the interacting traits. The predictions it makes expand our understanding of possible shared molecular interactions and therapeutic targets for asthma, where no cure is currently available

The problem of interpretation in vignette methodology in research with young people

In this paper we explore how interpretation is dealt with by researchers using a vignette methodology. Researchers using vignette methodology often struggle with interpretation: how to interpret the responses when participants shift between discussing the vignettes as themselves, taking the perspective of the character in the vignette and commenting on what ‘ought’ to happen. We argue that by foregrounding a consideration of the method with an explicitly articulated theoretical position of dialogicality, issues inherent in interpretation become a valuable addition to the research rather than an obstacle to be overcome. In the paper we discuss ‘Louise’ a young carer, detailing the various positions she takes in her talk about the vignette of Mary, a fictitious young carer, to illustrate how a perspective based in dialogical theory contributed to the analysis of her various moves through different identity positions

On the Influence of Magnetic Fields on the Structure of Protostellar Jets

We here present the first results of fully three-dimensional (3-D) MHD simulations of radiative cooling pulsed (time-variable) jets for a set of parameters which are suitable for protostellar outflows. Considering different initial magnetic field topologies in approximate $equipartition$ with the thermal gas, i.e., (i) a longitudinal, and (ii) a helical field, both of which permeating the jet and the ambient medium; and (iii) a purely toroidal field permeating only the jet, we find that the overall morphology of the pulsed jet is not very much affected by the presence of the different magnetic field geometries in comparison to a nonmagnetic calculation. Instead, the magnetic fields tend to affect essentially the detailed structure and emission properties behind the shocks at the head and at the pulse-induced internal knots, particularly for the helical and toroidal geometries. In these cases, we find, for example, that the $H_\alpha$ emissivity behind the internal knots can be about three to four times larger than that of the purely hydrodynamical jet. We also find that some features, like the nose cones that often develop at the jet head in 2-D calculations involving toroidal magnetic fields, are smoothed out or absent in the 3-D calculations.Comment: 13 pages, 3 figures, Accepted by ApJ Letters after minor corrections (for high resolution figures, see http://www.iagusp.usp.br/~adriano/h.tar

Systematic Errors in Cosmic Microwave Background Interferometry

Cosmic microwave background (CMB) polarization observations will require superb control of systematic errors in order to achieve their full scientific potential, particularly in the case of attempts to detect the B modes that may provide a window on inflation. Interferometry may be a promising way to achieve these goals. This paper presents a formalism for characterizing the effects of a variety of systematic errors on interferometric CMB polarization observations, with particular emphasis on estimates of the B-mode power spectrum. The most severe errors are those that couple the temperature anisotropy signal to polarization; such errors include cross-talk within detectors, misalignment of polarizers, and cross-polarization. In a B mode experiment, the next most serious category of errors are those that mix E and B modes, such as gain fluctuations, pointing errors, and beam shape errors. The paper also indicates which sources of error may cause circular polarization (e.g., from foregrounds) to contaminate the cosmologically interesting linear polarization channels, and conversely whether monitoring of the circular polarization channels may yield useful information about the errors themselves. For all the sources of error considered, estimates of the level of control that will be required for both E and B mode experiments are provided. Both experiments that interfere linear polarizations and those that interfere circular polarizations are considered. The fact that circular experiments simultaneously measure both linear polarization Stokes parameters in each baseline mitigates some sources of error.Comment: 19 pages, 9 figures, submitted to Phys. Rev.

Mosaicking with cosmic microwave background interferometers

Measurements of cosmic microwave background (CMB) anisotropies by interferometers offer several advantages over single-dish observations. The formalism for analyzing interferometer CMB data is well developed in the flat-sky approximation, valid for small fields of view. As the area of sky is increased to obtain finer spectral resolution, this approximation needs to be relaxed. We extend the formalism for CMB interferometry, including both temperature and polarization, to mosaics of observations covering arbitrarily large areas of the sky, with each individual pointing lying within the flat-sky approximation. We present a method for computing the correlation between visibilities with arbitrary pointing centers and baselines and illustrate the effects of sky curvature on the l-space resolution that can be obtained from a mosaic.Comment: 9 pages; submitted to Ap

Untreated and Enzyme-Modified Bovine Whey Products Reduce Association of Salmonella Typhimurium, Escherichia coli O157:H7 and Cronobacter malonaticus (formerly Enterobacter sakazakii) to CaCo-2 Cells

Adhesion of a micro-organism to a cell surface is often considered to be the first step in pathogenesis. Inhibiting this process may have therapeutic effects in vivo. This study investigates the inhibitory effects of various bovine whey products on the association of Salm. Typhimurium, E. coli O157:H7 and C. malonaticus (formerly Enterobacter sakazakii) to the human CaCo-2 cell line. Invasion of CaCo-2 cells by Salm. Typhimurium and C. malonaticus was also examined

Spausdinimo senosiomis spaudos staklėmis judėjimas

At the end of the twentieth century, increased access to certain technologies and processes, such as 3D scanning, computer-aided design, rapid fabrication and microcircuitry, enabled consumers to become creators of material design. These activities, which collectively came to be known as making, extended across both public and private sectors, including the study of the book. This paper offers an extended discourse on the full range of activities comprising the bibliographical maker movement, which in recent years has coalesced around the idea that maker culture may be employed to enhance our understanding of not only the history but also the future of the book. The application of these new technologies toward critical book studies has proceeded from the practice-based approach to research and instruction first begun under the auspices of the bibliographical press movement in the mid-twentieth century. In keeping with this earlier work, biblio-making is predicated upon the idea that certain kinds of knowledge are best gained through personal experience and experimentation. This article will first outline the benefits of applying 3D technologies to the goals of book history before locating and describing the activities of participating individuals and institutions within three broad categories: holistic, 3D digitisation; recovering historical tools and processes; and creative experiments in book design. As the article demonstrates, the strength and potential of the bibliographical maker movement lies in its widening community of practice and that, by virtue of its being an open-access network of constituents, it is now poised to make a significant and lasting contribution to the study of the book.XX a. pabaigoje padidėjusi prieiga prie tam tikrų technologijų ir procesų tokių kaip 3D skenavimas, kompiuterinis projektavimas, sparti gamyba bei mikroschemos leido vartotojams tapti medžiagų dizaino kūrėjais. Ši veikla, kuri apibendrintai pradėta vadinti „kūrimu“ (angl. making), apėmė viešąjį ir privatų sektorius, įskaitant knygų tyrimus. Šiame straipsnyje pateikiamas platus visos veiklos spektro diskursas, apimantis spausdinimo senosiomis spaudos staklėmis kūrėjų judėjimą, kuris pastaraisiais metais susiliejo su idėja, skelbiančia, kad kūrėjų kultūra gali būti pasitelkta siekiant pagerinti mūsų supratimą ne tik apie knygos istoriją, bet ir jos ateitį. Šių naujų technologijų taikymas kritiniams knygų tyrimams kilo iš praktika pagrįsto požiūrio į tyrimus, o mokymai pirmiausia buvo pradėti XX a. viduryje pasitelkiant spausdinimo senosiomis spaudos staklėmis judėjimą. Remiantis šiuo ankstesniu darbu, knygų kūrimas grindžiamas idėja, kad tam tikras žinias geriausia įgyti per asmeninę patirtį ir bandymus. Šiame straipsnyje pirmiausia apibūdinami 3D technologijų taikymo knygų istorijos tikslams pranašumai prieš nustatant ir aprašant dalyvaujančių asmenų ir institucijų trijų plačių kategorijų veiklą: holistinę, 3D skaitmeninimą; istorinių įrankių ir procesų atkūrimą; kūrybinius knygų dizaino eksperimentus. Kaip rodo straipsnis, bibliografijos kūrėjų judėjimo stiprybė ir potencialas slypi besiplečiančioje aktyvioje bendruomenėje, o kadangi tai yra atvirosios prieigos elementų tinklas, tai dabar ji pasirengusi įnešti reikšmingą ir ilgalaikį indėlį į knygų tyrimą

The Performance of US Bond Mutual Funds

We evaluate the performance of the US bond mutual fund industry using a comprehensive sample of bond funds over a long time period from January 1998 to February 2017. In this one study, we evaluate bond fund selectivity, market timing and performance persistence. We evaluate bond funds relative to their self-declared benchmarks and in terms of both gross-of-fee returns and net-of-fee returns. We document considerable abnormal performance among funds both to the fund (gross returns) and to the investor (net returns). Bond fund performance is found to be superior in the post financial crisis period. However, past strong performance cannot be relied upon to predict future performance. Finally, while some funds exhibit market timing ability; we find a predominance of negative market timing among US bond mutual funds