Sample variance, source clustering and their influence on the counts of faint radio sources

The shape of the curves defined by the counts of radio sources per unit area as a function of their flux density was one of the earliest cosmological probes. Radio source counts continue to be an area of astrophysical interest as they can be used to study the relative populations of galaxy types in the Universe (as well as investigate any cosmological evolution in their respective luminosity functions). They are also a vital consideration for determining howsource confusion may limit the depth of a radio interferometer observation, and are essential for characterizing the extragalactic foregrounds in cosmicmicrowave background experiments. There is currently no consensus as to the relative populations of the faintest (sub-mJy) source types, where the counts show a turn-up. Most of the source count data in this regime are gathered from multiple observations that each use a deep, single pointing with an interferometric radio telescope. These independent count measurements exhibit large amounts of scatter (factors of the order of a few) that significantly exceeds their respective stated uncertainties. In this paper, we use a simulation of the extragalactic radio continuum emission to assess the level at which sample variance may be the cause of the scatter. We find that the scatter induced by sample variance in the simulated counts decreases towards lower flux density bins as the raw source counts increase. The field-to-field variations make significant contributions to the scatter in the measurements of counts derived from deep observations that consist of a single pointing, and could even be the sole cause at >100 μJy. We present a method for evaluating the flux density limit that a radio survey must reach in order to reduce the count uncertainty induced by sample variance to a specific value. We also derive a method for correcting Poisson errors on source counts from existing and future deep radio surveys in order to include the uncertainties due to the cosmological clustering of sources. A conclusive empirical constraint on the effect of sample variance at these low luminosities is unlikely to arise until the completion of future large-scale radio surveys with next-generation radio telescopes.Web of Scienc

Separate processing of texture and form in the ventral stream : evidence from fMRI and visual agnosia.

Real-life visual object recognition requires the processing of more than just geometric (shape, size, and orientation) properties. Surface properties such as color and texture are equally important, particularly for providing information about the material properties of objects. Recent neuroimaging research suggests that geometric and surface properties are dealt with separately, within the lateral occipital cortex (LOC) and the collateral sulcus (CoS), respectively. Here we compared objects that either differed in aspect ratio or in surface texture only, keeping all other visual properties constant. Results on brain-intact participants confirmed that surface texture activates an area in the posterior CoS, quite distinct from the area activated by shape within LOC. We also tested two patients with visual object agnosia, one of whom (DF) performed well on the texture task but at chance on the shape task, while the other (MS) showed the converse pattern. This behavioral double dissociation was matched by a parallel neuroimaging dissociation, with activation in CoS but not LOC in patient DF, and activation in LOC but not CoS in patient MS. These data provide presumptive evidence that the areas respectively activated by shape and texture play a causally necessary role in the perceptual discrimination of these features

Hydrocarbon formation and oxidation in spark-ignition engines

This report summarizes the key results and conceptual findings from a three year research program on hydrocarbon formation and oxidation mechanisms in spark-ignition engines. Research was carried out in four areas: laminar flame quenching experimental and analytical studies; quench layer studies in a spark-ignition engine using a rapid-acting gas sampling valve; flow visualization studies in a transparent engine to determine quench layer and quench crevice gas motion; studies of heat transfer, mixing and HC oxidation in the exhaust port. More detailed descriptions of the individual research activities in these areas can be found in the theses and publications completed to date which form Volumes II to XI of the final report on this program.Final report on a research program funded by General Motors Research Laboratories, September 1976 to August 1979

MicroRNA-194 modulates glucose metabolism and its skeletal muscle expression is reduced in diabetes

BACKGROUND: The regulation of microRNAs (miRNAs) at different stages of the progression of type 2 diabetes mellitus (T2DM) and their role in glucose homeostasis was investigated. METHODS: Microarrays were used to assess miRNA expression in skeletal muscle biopsies taken from healthy individuals and patients with pre-diabetes or T2DM, and insulin resistant offspring of rat dams fed a high fat diet during pregnancy. RESULTS: Twenty-three miRNAs were differentially expressed in patients with T2DM, and 7 in the insulin resistant rat offspring compared to their controls. Among these, only one miRNA was similarly regulated: miR-194 expression was significantly reduced by 25 to 50% in both the rat model and in human with pre-diabetes and established diabetes. Knockdown of miR-194 in L6 skeletal muscle cells induced an increase in basal and insulin-stimulated glucose uptake and glycogen synthesis. This occurred in conjunction with an increased glycolysis, indicated by elevated lactate production. Moreover, oxidative capacity was also increased as we found an enhanced glucose oxidation in presence of the mitochondrial uncoupler FCCP. When miR-194 was down-regulated in vitro, western blot analysis showed an increased phosphorylation of AKT and GSK3β in response to insulin, and an increase in expression of proteins controlling mitochondrial oxidative phosphorylation. CONCLUSIONS: Type 2 diabetes mellitus is associated with regulation of several miRNAs in skeletal muscle. Interestingly, miR-194 was a unique miRNA that appeared regulated across different stages of the disease progression, from the early stages of insulin resistance to the development of T2DM. We have shown miR-194 is involved in multiple aspects of skeletal muscle glucose metabolism from uptake, through to glycolysis, glycogenesis and glucose oxidation, potentially via mechanisms involving AKT, GSK3 and oxidative phosphorylation. MiR-194 could be down-regulated in patients with early features of diabetes as an adaptive response to facilitate tissue glucose uptake and metabolism in the face of insulin resistance

Decadal ocean forcing and Antarctic ice sheet response: Lessons from the Amundsen Sea

Mass loss from the Antarctic Ice Sheet is driven by changes at the marine margins. In the Amundsen Sea, thinning of the ice shelves has allowed the outlet glaciers to accelerate and thin, resulting in inland migration of their grounding lines. The ultimate driver is often assumed to be ocean warming, but the recent record of ocean temperature is dominated by decadal variability rather than a trend. The distribution of water masses on the Amundsen Sea continental shelf is particularly sensitive to atmospheric forcing, while the regional atmospheric circulation is highly variable, at least in part because of the impact of tropical variability. Changes in atmospheric circulation force changes in ice shelf melting, which drive step-wise movement of the grounding line between localized high points on the bed. When the grounding line is located on a high point, outlet glacier flow is sensitive to atmosphere-ocean variability, but once retreat or advance to the next high point has been triggered, ocean circulation and melt rate changes associated with the evolution in geometry of the sub-ice-shelf cavity dominate, and the sensitivity to atmospheric forcing is greatly reduced

Anarchy in the UK: Reading Beryl the Peril via historic conceptions of childhood

© 2014 Taylor & Francis. Much work within the field of childhood studies has focused on the social discourses through which childhood is understood. This article draws on this work in developing a critical framework for considering the appeal of Beryl the Peril. The article examines the influence of conceptualisations of childhood prevalent in the nineteenth and early twentieth centuries. These theorised children as disruptive and requiring restraint. Approved literature for children sought to socialise them into the adult order. However, a more subversive strain, identifiable in Lewis Carroll's Alice novels, celebrated an anarchic vision of childhood. This article examines how Beryl the Peril negotiated these conflicting conceptions of childhood. Beryl is an unruly force; her opponent, and representative of social authority, is Dad. Their clashes play out the tensions in these articulations of childhood. The development of Beryl over nearly 60 years provides an opportunity to examine how her subversive spirit has remained appealing

New models of care: a liaison psychiatry service for medically unexplained symptoms and frequent attenders in primary care

Aims and method: This paper describes the process of setting up and the early results from a new liaison psychiatry service in primary care for people identified as frequent general practice attenders with long-term conditions or medically unexplained symptoms. Using a rapid evidence synthesis, we identified existing service models, mechanisms to identify and refer patients, and outcomes for the service. Considering this evidence, with local contingencies we defined options and resources. We agreed a model to set up a service in three diverse general practices. An evaluation explored the feasibility of the service and of collecting data for clinical, service and economic outcomes. Results: High levels of patient and staff satisfaction, and reductions in the utilisation of primary and secondary healthcare, with associated cost savings are reported. Clinical implications: A multidisciplinary liaison psychiatry service integrated in primary care is feasible and may be evaluated using routinely collected data

Philosophical and Educational Perspectives on Engineering and Technological Literacy, IV

In this fourth edition of Philosophical Perspectives on Engineering and Technological Literacy, the divisional publication of the Technological and Engineering Literacy and Philosophy of Engineering (TELPhE) Division of ASEE, is trying a new format. Over the years members of the division have noted that many of us keep coming back to the annual ASEE conference year after year not only for the technical papers, but the deep and wide-ranging conversations that crop up organically and spontaneously at the conference like flowers in the desert after a rain. This may be an appropriate metaphor since within our own academic institutions the opportunities to have wide ranging conversations with others who have similar interests in the larger questions that underlie engineering education are often difficult to start or hard to find. Such conversations matter; dialog is fundamental to the practice of both philosophy and literacy. It is a truism to say that we learn through interacting with others and refine our own ideas by sharpening them against those of others. However the practical reality of a conference is to at least not lose money and that of today’s academic life is to publish one’s work. In conjunction, however, these have the effect of steering academic writing towards papers and presentations rather than free ranging dialog. For TELPhE, a group focused on the ideas and narratives that underlie the learning of engineering, it is not clear that such outward facing, many-to-one, ways of communicating are by themselves meeting the Division’s needs. As Mark Twain is alleged to have said, “Let us make a special effort to stop communicating with each other, so we can have some conversation.” This edition begins with an anchoring paper, John Heywood’s Why Technological Literacy and for Whom? which was presented at the 2016 ASEE Annual Conference and Exhibition in New Orleans, Louisiana. In this paper Professor Heywood’s intent was “raise questions about the intent of technological literacy in society at the present time.” Following the ASEE conference a call was put out to all members of the TELPhE Division asking for short responses to Professor Heywood’s paper. These responses, in random order, follow the anchoring paper. Unlike more traditional journals each author was free to comment in the style and form they best saw fit; instruction for style and formatting were minimal to non-existent. The author’s papers have been left mostly “as is” with only consistency between fonts, layout, and similar issues addressed. In cases where a title was not provided by the author one was inserted; apologies to the authors in advance. It is hoped that this form of “dialog journal” will enable a wider ranging conversation within TELPhE that spans not only those who can attend the ASEE conference and whom stumble in to conversation, but also those whose time, circumstance, and resources don’t give them opportunities to attend. The larger goal of this format is to stimulate ongoing dialogs and capture them in ways that are both readable and archival.https://lib.dr.iastate.edu/ece_books/1003/thumbnail.jp