Searching for high-redshift centimeter-wave continuum, line and maser emission using the Square Kilometer Array

We discuss the detection of redshifted line and continuum emission at radio wavelengths using a Square Kilometer Array (SKA), specifically from low-excitation rotational molecular line transitions of CO and HCN (molecular lines), the recombination radiation from atomic transitions in almost-ionized hydrogen (radio recombination lines; RRLs), OH and water maser lines, as well as from synchrotron and free-free continuum radiation and HI 21-cm line radiation. The detection of radio lines with the SKA offers the prospect to determine the redshifts and thus exact luminosities for some of the most distant and optically faint star-forming galaxies and active galactic nuclei (AGN), even those galaxies that are either deeply enshrouded in interstellar dust or shining prior to the end of reionization. Moreover, it provides an opportunity to study the astrophysical conditions and resolved morphologies of the most active regions in galaxies during the most active phase of star formation at redshift z~2. A sufficiently powerful and adaptable SKA correlator will enable wide-field three-dimensional redshift surveys at chosen specific high redshifts, and will allow new probes of the evolution of large-scale structure (LSS) in the distribution of galaxies. The detection of molecular line radiation favours pushing the operating frequencies of SKA up to at least 26 GHz, and ideally to 40 GHz, while very high redshift maser emissions requires access to about 100 MHz. To search for LSS the widest possible instantaneous field of view would be advantageous.Comment: 12 pages, 2 figures. To appear in "Science with the Square Kilometer Array," eds. C. Carilli and S. Rawlings, New Astronomy Reviews (Elsevier: Amsterdam

Australia: PISA Australia—Excellence and Equity?

Australia’s education system reflects its history of federalism. State and territory governments are responsible for administering education within their jurisdiction and across the sector comprising government (public), Catholic systemic and other independent schooling systems. They collaborate on education policy with the federal government. Over the past two decades the federal government has taken a greater role in funding across the education sector, and as a result of this involvement and the priorities of federal governments of the day, Australia now has one of the highest rates of non-government schooling in the OECD. Funding equity across the sectors has become a prominent issue. Concerns have been compounded by evidence of declining student performance since Australia’s initial participation in PISA in 2000, and the increasing gap between our high achievers and low achievers. This chapter explores Australia’s PISA 2018 results and what they reveal about the impact of socioeconomic level on student achievement. It also considers the role of school funding and the need to direct support to those schools that are attempting to educate the greater proportion of an increasingly diverse student population including students facing multiple layers of disadvantage

A Dense Gas Trigger for OH Megamasers

HCN and CO line diagnostics provide new insight into the OH megamaser (OHM) phenomenon, suggesting a dense gas trigger for OHMs. We identify three physical properties that differentiate OHM hosts from other starburst galaxies: (1) OHMs have the highest mean molecular gas densities among starburst galaxies; nearly all OHM hosts have = 10^3-10^4 cm^-3 (OH line-emitting clouds likely have n(H2) > 10^4 cm^-3). (2) OHM hosts are a distinct population in the nonlinear part of the IR-CO relation. (3) OHM hosts have exceptionally high dense molecular gas fractions, L(HCN)/L(CO)>0.07, and comprise roughly half of this unusual population. OH absorbers and kilomasers generally follow the linear IR-CO relation and are uniformly distributed in dense gas fraction and L(HCN), demonstrating that OHMs are independent of OH abundance. The fraction of non-OHMs with high mean densities and high dense gas fractions constrains beaming to be a minor effect: OHM emission solid angle must exceed 2 pi steradians. Contrary to conventional wisdom, IR luminosity does not dictate OHM formation; both star formation and OHM activity are consequences of tidal density enhancements accompanying galaxy interactions. The OHM fraction in starbursts is likely due to the fraction of mergers experiencing a temporal spike in tidally driven density enhancement. OHMs are thus signposts marking the most intense, compact, and unusual modes of star formation in the local universe. Future high redshift OHM surveys can now be interpreted in a star formation and galaxy evolution context, indicating both the merging rate of galaxies and the burst contribution to star formation.Comment: 5 pages, 3 figures, 1 table, accepted by ApJ Letter

A New H I Survey of Active Galaxies

We have conducted a new Arecibo survey for H I emission for 113 galaxies with broad-line (type 1) active galactic nuclei (AGNs) out to recession velocities as high as 35,000 km/s. The primary aim of the study is to obtain sensitive H I spectra for a well-defined, uniformly selected sample of active galaxies that have estimates of their black hole masses in order to investigate correlations between H I properties and the characteristics of the AGNs. H I emission was detected in 66 out of the 101 (65%) objects with spectra uncorrupted by radio frequency interference, among which 45 (68%) have line profiles with adequate signal-to-noise ratio and sufficiently reliable inclination corrections to yield robust deprojected rotational velocities. This paper presents the basic survey products, including an atlas of H I spectra, measurements of H I flux, line width, profile asymmetry, optical images, optical spectroscopic parameters, as well as a summary of a number of derived properties pertaining to the host galaxies. To enlarge our primary sample, we also assemble all previously published H I measurements of type 1 AGNs for which can can estimate black hole masses, which total an additional 53 objects. The final comprehensive compilation of 154 broad-line active galaxies, by far the largest sample ever studied, forms the basis of our companion paper, which uses the H I database to explore a number of properties of the AGN host galaxies.Comment: To appear in ApJS; 31 pages. Preprint will full-resolution figures can be downloaded from http://www.ociw.edu/~lho/preprints/ms1.pd

Effects of Dietary Sodium Intake on Blood Flow Regulation During Exercise in Salt Resistant Individuals

PURPOSE: Dietary sodium intake guidelines is ≤2,300 mg/day, yet is exceeded by 90% of Americans. This study examined the impact of a high sodium diet on blood flow regulation during exercise. METHODS: Six males (25 ± 2 years) consumed dietary sodium intake guidelines for two weeks, with one week salt-capsule supplemented (HS: 6,900 mg/day of sodium) and the other week placebo-capsule supplemented (LS: 2,300 mg/day of sodium). At the end of each week, peripheral hemodynamic measurements [blood flow (BF), shear rate (SR), and flow mediated dilation (FMD)/SR)] of the brachial and superficial femoral artery were taken during handgrip (HG) and plantar flexion (PF) exercise, respectively. Each exercise workload was 3 minutes and progressed by 8 kilograms until exhaustion. RESULTS: There were no differences between LS and HS in blood pressure (82 ± 4 v 80 ± 5 mmHg; p = 0.3) or heart rate (56 ± 6 v 59 ± 10 bpm; p = 0.4). HG and PF exercise increased BF, SR, and FMD/SR across workload (p \u3c 0.03 for all), but no difference between diets (p \u3e 0.05 for all). CONCLUSION: Despite previous reports that HS impairs resting vascular function, this study revealed that peripheral vascular function and blood flow regulation during exercise is not impacted by a HS diet.https://scholarscompass.vcu.edu/gradposters/1082/thumbnail.jp

An Examination of Performance of First Year Students at an Ontario University: An Admission Perspective

Major changes in the Ontario secondary school system over the last 15 years have increased the concerns within some universities about the use of Grade 13 marks as the principal criterion for evaluating applicants. These concerns focus on grade inflation, variability of marks among schools, and how appropriate some subjects are for university admission. This paper reports on a study of these issues conducted at McMaster University. The relationship between Grade 13 admission and Year I university averages was examined. Two issues that have received little attention elsewhere were also examined: how Year I performance varied by applicant status, and the relationship between individual Grade 13 subjects and Year I performance. The results indicate that Grade 13 marks, which are the only measure of a student's achievement available, continue to be a reasonable predictor of subsequent performance in Year I. Grade 13 subjects were identified that were more consistently associated with Year I performance than others. There was also evidence that some Grade 13 subjects may be contributing to an "inflated" admission average. The results of this study should be useful in evaluating existing admission policies and in the development of the new Ontario Academic Courses.Au cours des 15 dernières années, de sérieux changements dans le système des écoles secondaires de l'Ontario ont ajouté à l'inquiétude qui règne au sein de certaines universités face à l'emploi des notes de la 13e année comme critère principal d'évaluation des candidats universitaires. Ces craintes se centrent sur des notes "gonflées", sur une notation variable d'école en école et sur la pertinence de certains cours à l'entrée universitaire. Ce papier traite d'une étude à ce sujet, menée à l'université McMaster, qui visait à percevoir les rapports entre la moyenne d'admission de la 13e année et celle de la lere année universitaire. L'étude porta également sur l'écart entre la performance universitaire et le statut du candidat et sur la performance universitaire reliée à certaines matières de la 13e année, deux questions qui avaient suscité jusqu 'ici peu d'intérêt. Les résultats de cette étude indiquent que les notes de la 13e année, qui sont le seul système de mesure actuel du rendement scolaire, n'en demeurent pas moins un indice valide de la performance post-secondaire. Dans ce rapport, certaines matières de 13e année furent identifiées et étroite-ment associées au succès universitaire. Les découvertes signalèrent également un rapport probable entre certains sujets de 13e année et la hausse dans la moyenne d'admission. Toutes ces données devraient servira évaluer les procédures actuelles d'admission et servir à la mise sur pied de nouveaux 'cours pré-universitaires'

New limits for neutrinoless tau decays

Neutrinoless 3-prong tau lepton decays into a charged lepton and either two charged particles or one neutral meson have been searched for using 4.79fb^(-1) of data collected with the CLEO II detector at Cornell Electron Storage Ring. This analysis represents an update of a previous study and the addition of six decay channels. In all channels the numbers of events found are compatible with background estimates and branching fraction upper limits are set for 28 different decay modes. These limits are either more stringent than those set previously or represent the first attempt to find these decays

A Search for OH Megamasers at z > 0.1. I. Preliminary Results

We present the preliminary results of a survey for OH megamasers underway at the Arecibo Observatory. The goals of the survey are to calibrate the luminosity function of OH megamasers to the low-redshift galaxy merger rate (0.1 < z < 0.2), and to use the enhanced sample of OH megamasers provided by the survey to study OH megamaser environments, engines, lifetimes, and structure. The survey should double the known OH megamaser sample to roughly 100 objects. Survey results will be presented in installments to facilitate community access to the data. Here we report the discovery of 11 OH megamasers and one OH absorber, and include upper limits on the isotropic 1667 MHz OH line luminosity of 53 other luminous infrared galaxies at z > 0.1. The new megamasers show a wide range of spectral properties, but are consistent with the extant set of 55 previously reported objects, only 8 of which have z > 0.1.Comment: 18 pages, 3 figures, accepted for publication in the Astronomical Journa

Aharonov-Bohm-like effect for light propagating in nematics with disclinations

Using a geometric approach for the propagation of light in anisotropic media, we investigate what effect the director field of disclinations may have on the polarization state of light. Parallel transport around the defect, of the spinor describing the polarization, indicates the acquisition of a topological phase, in analogy with the Aharonov-Bohm effect.Comment: 6 pages, to appear in Europhysics Letter