Radio Sources in the Local Universe

This thesis presents a census of radio sources selected from the NRAO (National Radio Astronomy Observatory) VLA (Very Large Array) Sky Survey (NVSS) and Sydney University Molonglo Sky Survey (SUMSS) catalogues which have also been observed in the first data release of the 6 degree Field Galaxy Survey (6dFGS), a galaxy redshift survey of the local universe. Radio detections were found for 4,506 galaxies in the 6dFGS near-infrared-selected primary sample, a radio detection rate of 16%. A further 1,196 radio sources were observed by 6dF which were missing from the 6dFGS primary sample either because their host galaxies were too blue in colour or they appeared stellar on optical plates. The full sample comprises the largest and most homogeneous set of spectra and redshifts of radio sources in the local universe ever obtained. Results from the study of these objects form an accurate benchmark from which their cosmic evolution may be understood. 6dF spectra of galaxies have been used to determine the physical cause of radio emission from each object as either star formation or an active galactic nucleus powered by a super-massive black hole. These two classes of radio source have been characterised via a determination of the local radio luminosity function at 1.4 GHz; plotting the variation in their space density with luminosity. The star-formation density of the universe at the present epoch has been determined, the value of which which turns out to be in excellent agreement with previously published values. Fractional luminosity functions have also been determined showing that more massive galaxies have higher star-formation rates and are more likely to host a radio-loud AGN. The large-scale structure of star-forming galaxies and radio-loud AGN in the local universe has been studied by determining their clustering properties via the two-point correlation function. Radio-loud AGN are found to cluster more strongly than star-forming galaxies confirming that these objects are biased tracers of the underlying matter distribution. Both star-forming galaxies and AGNs cluster similarly to the underlying host galaxy population in which they reside. This thesis also describes the 843 MHz SUMSS catalogue, made by fitting elliptical Gaussians to sources in images. The catalogue contains radio sources to a limiting peak brightness of 6 mJy/beam at declination less than -50 degrees and 10 mJy/beam at declination greater than -50 degrees. Image artefacts have been classified using a novel technique involving a decision tree, which correctly identifies and rejects spurious sources in over 96% of cases and has ensured the catalogue is more than 95% complete and 90% reliable over most of its flux density range

Effect of Low Energy, High Fiber Diets on Digestibility Traits in Pigs Selected for Residual Feed Intake

In this study, barrows and gilts from the Iowa State University Residual Feed Intake selection lines were fed two diets. The first, the Control diet, was corn and soybean-meal based, and was high in energy yet low in fiber content. The second, the Fiber diet, substituted in corn bran, wheat middlings, and soybean hulls, and resulted in a lower energy and higher fiber diet. These two diets were fed to pigs that had previously been selected for increased and decreased feed efficiency over the course of 8 generations based on residual feed intake. Fecal grab samples were collected from these pigs during the first and third finishing growth-phases with the objective of evaluating differences in dry matter, gross energy, nitrogen, and neutral detergent fiber digestibility between the two genetic lines and the two diets. This study observed beneficial increases in digestibility of fibrous feed components in pigs selected for increased feed efficiency

Iteratively Training Look-Up Tables for Network Quantization

Operating deep neural networks (DNNs) on devices with limited resources requires the reduction of their memory as well as computational footprint. Popular reduction methods are network quantization or pruning, which either reduce the word length of the network parameters or remove weights from the network if they are not needed. In this article we discuss a general framework for network reduction which we call `Look-Up Table Quantization` (LUT-Q). For each layer, we learn a value dictionary and an assignment matrix to represent the network weights. We propose a special solver which combines gradient descent and a one-step k-means update to learn both the value dictionaries and assignment matrices iteratively. This method is very flexible: by constraining the value dictionary, many different reduction problems such as non-uniform network quantization, training of multiplierless networks, network pruning or simultaneous quantization and pruning can be implemented without changing the solver. This flexibility of the LUT-Q method allows us to use the same method to train networks for different hardware capabilities.Comment: Copyright 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other work

Expression Profile Matrix of Arabidopsis Transcription Factor Genes Suggests Their Putative Functions in Response to Environmental Stresses

Numerous studies have shown that transcription factors are important in regulating plant responses to environmental stress. However, specific functions for most of the genes encoding transcription factors are unclear. In this study, we used mRNA profiles generated from microarray experiments to deduce the functions of genes encoding known and putative Arabidopsis transcription factors. The mRNA levels of 402 distinct transcription factor genes were examined at different developmental stages and under various stress conditions. Transcription factors potentially controlling downstream gene expression in stress signal transduction pathways were identified by observed activation and repression of the genes after certain stress treatments. The mRNA levels of a number of previously characterized transcription factor genes were changed significantly in connection with other regulatory pathways, suggesting their multifunctional nature. The expression of 74 transcription factor genes responsive to bacterial pathogen infection was reduced or abolished in mutants that have defects in salicylic acid, jasmonic acid, or ethylene signaling. This observation indicates that the regulation of these genes is mediated at least partly by these plant hormones and suggests that the transcription factor genes are involved in the regulation of additional downstream responses mediated by these hormones. Among the 43 transcription factor genes that are induced during senescence, 28 of them also are induced by stress treatment, suggesting extensive overlap responses to these stresses. Statistical analysis of the promoter regions of the genes responsive to cold stress indicated unambiguous enrichment of known conserved transcription factor binding sites for the responses. A highly conserved novel promoter motif was identified in genes responding to a broad set of pathogen infection treatments. This observation strongly suggests that the corresponding transcription factors play general and crucial roles in the coordinated regulation of these specific regulons. Although further validation is needed, these correlative results provide a vast amount of information that can guide hypothesis-driven research to elucidate the molecular mechanisms involved in transcriptional regulation and signaling networks in plants

Merkel Cell Polyomavirus DNA in Persons without Merkel Cell Carcinoma

Merkel cell polyomavirus (MCPyV) DNA was detected in 88% of Merkel cell carcinomas in contrast to 16% of other skin tumors. MCPyV was also found in anogenital and oral samples (31%) and eyebrow hairs (50%) of HIV-positive men and in forehead swabs (62%) of healthy controls. MCPyV thus appears to be widespread

Herschel-ATLAS/GAMA: A difference between star formation rates in strong-line and weak-line radio galaxies

We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields. Classifying the radio sources in terms of their optical spectra, we find that strong-emission-line sources ('high-excitation radio galaxies') have, on average, a factor of ~4 higher 250-μm Herschel luminosity than weak-line ('lowexcitation') radio galaxies and are also more luminous than magnitude-matched radio-quiet galaxies at the same redshift. Using all five H-ATLAS bands, we show that this difference in luminosity between the emission-line classes arises mostly from a difference in the average dust temperature; strong-emission-line sources tend to have comparable dust masses to, but higher dust temperatures than, radio galaxies with weak emission lines. We interpret this as showing that radio galaxies with strong nuclear emission lines are much more likely to be associated with star formation in their host galaxy, although there is certainly not a one-to-one relationship between star formation and strong-line active galactic nuclei (AGN) activity. The strong-line sources are estimated to have star formation rates at least a factor of 3-4 higher than those in the weak-line objects. Our conclusion is consistent with earlier work, generally carried out using much smaller samples, and reinforces the general picture of high-excitation radio galaxies as being located in lower-mass, less evolved host galaxies than their low-excitation counterparts.Peer reviewe

Pattern representation and recognition with accelerated analog neuromorphic systems

Despite being originally inspired by the central nervous system, artificial neural networks have diverged from their biological archetypes as they have been remodeled to fit particular tasks. In this paper, we review several possibilites to reverse map these architectures to biologically more realistic spiking networks with the aim of emulating them on fast, low-power neuromorphic hardware. Since many of these devices employ analog components, which cannot be perfectly controlled, finding ways to compensate for the resulting effects represents a key challenge. Here, we discuss three different strategies to address this problem: the addition of auxiliary network components for stabilizing activity, the utilization of inherently robust architectures and a training method for hardware-emulated networks that functions without perfect knowledge of the system's dynamics and parameters. For all three scenarios, we corroborate our theoretical considerations with experimental results on accelerated analog neuromorphic platforms.Comment: accepted at ISCAS 201

Assessment of potential cardiotoxic side effects of mitoxantrone in patients with multiple sclerosis

Previous studies showed that mitoxantrone can reduce disability progression in patients with multiple sclerosis (MS). There is, however, concern that it may cause irreversible cardiomyopathy with reduced left ventricular (LV) ejection fraction (EF) and congestive heart failure. The aim of this prospective study was to investigate cardiac side effects of mitoxantrone by repetitive cardiac monitoring in MS patients. The treatment protocol called for ten courses of a combined mitoxantrone (10 mg/m(2) body surface) and methylprednisolone therapy. Before each course, a transthoracic echocardiogram was performed to determine the LV end-diastolic diameter, the end-systolic diameter and the fractional shortening; the LV-EF was calculated. Seventy-three patients participated (32 males; age 48 +/- 12 years, range 20-75 years; 25 with primary progressive, 47 with secondary progressive and 1 with relapsing-remitting MS) who received at least four courses of mitoxantrone. Three of the 73 patients were excluded during the study (2 patients discontinued therapy; 1 patient with a previous history of ischemic heart disease developed atrial fibrillation after the second course of mitoxantrone). The mean cumulative dose of mitoxantrone was 114.0 +/- 33.8 mg. The mean follow-up time was 23.4 months (range 10-57 months). So far, there has been no significant change in any of the determined parameters (end-diastolic diameter, end-systolic diameter, fractional shortening, EF) over time during all follow-up investigations. Mitoxantrone did not cause signs of congestive heart failure in any of the patients. Further cardiac monitoring is, however, needed to determine the safety of mitoxantrone after longer follow-up times and at higher cumulative doses. Copyright (C) 2005 S. Karger AG, Basel