Early Access: Elementary School Outcomes for Arkansas Better Chance Public Pre-Kindergarten Participants

Public pre-Kindergarten programs are frequently promoted as promising early interventions for at-risk students, as they can equip 3- and 4-year-olds with the cognitive, behavioral, and social skills necessary for success in Kindergarten and beyond. The Arkansas Better Chance (ABC) program provides low-income and at-risk Arkansas students with tuition-free pre-K opportunities in school districts across the state. The current analysis describes the 3rd and 5th grade outcomes of students who enroll in ABC pre-K programs in Arkansas public schools. In an attempt to understand how well these programs are serving students, we follow four cohorts of program participants through elementary school, and we compare their math and reading achievement test scores to those of similar peers who did not attend ABC programs. We find ABC pre-K participants are more likely to fall into demographic groups that are considered at-risk for low academic performance, and that ABC students outperform similar peers on math and reading achievement tests in 3rd grade in three of four cohorts. These findings suggest that this program has the potential to set students up for lasting academic success

Draws and Drawbacks of an Oxford Study Abroad Experience

Using qualitative research methodology, we interviewed 23 American students participating in a study abroad program at Oxford University in the U.K. Results showed four primary draws to participating in the study abroad program and two perceived drawbacks. Positively, Oxford’s first appealing dynamic related to the tutorial system and students’ expanded range of options for specialized topics as well as in-depth study. Next, participants highly valued Oxford’s academic rigor, which accompanied the university’s unique approach to education. Third, Oxford’s location in England appealed to our participants. Finally, students reported hopes that future benefits would result from their decisions to attend Oxford and perceived associations with Oxford’s prestige. As participants weighed these benefits of studying at OU, they contrasted the positive dynamics with two major drawbacks: finances and missed U.S. experiences. Nevertheless, our participants unanimously affirmed their respective decisions to study at Oxford and highly recommended the experience to future potential applicants

Secondary Electron Yield Measurements of Carbon Nanotube Forests: Dependence on Morphology and Substrate

Total, secondary, and backscatter electron yield data were taken with beam energies between 15 eV and 30 keV, in conjunction with energy emission data, to determine the extent of suppression of yield caused by carbon nanotube (CNT) forest coatings on substrates. CNT forests can potentially lower substrate yield due to both its inherently low-yield, low-atomic number (Z) carbon composition, and its bundled, high-aspect ratio structure. Rough surfaces, and in particular, surfaces with deep high-aspect-ratio voids, can suppress yields, as the electrons emitted from lower lying surfaces are recaptured by surface protrusions rather than escaping the near-surface region. Yields of multilayered materials can be modeled essentially serially as a combination of the constituents. However, it is shown that suppression of yields due to CNT forest morphology is more significant than simple predicted contributions of homogeneous layered components. This effect is found to be most pronounced at low energies, where the incident electrons interact preferentially with the CNTs. CNT forests between 20 and 50 μm tall were grown on a thick silicon substrate capped with a 3-nm diffusion barrier of evaporated aluminum using a wet injection chemical vapor deposition (CVD) method. Yields of an annealed substrate and constituent bulk materials were also investigated. At incident electron energies above ~1200 eV, the substrate secondary yield dominated those of the CNT forests, as incident electrons penetrated through the low-density, low-Z CNT forests, and backscattered from the higher-Z substrate. At lower energies \u3c1200 \u3eeV, the CNT forests substantially reduced the overall yields of the substrate, and for \u3c500 eV CNT forest yields were \u3c1, well below the already low yields of bulk graphite. This suppressed yield at low energies is attributed to the porosity and preferred vertical alignment of the CNT forest. The yield’s dependence on the height and density of the CNT forest is also discussed

Influence of Vibrationally-Induced Structural Changes on Carbon Nanotube Forests Suppression of Electron Yield

Carbon nanotube (CNT) forest coatings have been found to lower electron yield from material surfaces. The suppressed yields have been attributed to both the lower inherent yields of low-atomic number carbon and the enhanced electron recapture resulting from the morphology of the carbon layer. To explore the relative contributions of these two causes of yield suppression, tests have been made on CNT forest-coated conducting substrate samples subjected to vibrationally-induced changes of the coating structure. The extent of vibrationally-induced structural changes—due, for example, to shear-force conditions during space-vehicle transit—are of interest, as CNT have been a frequent topic of scientific curiosity and space applications due to their high tensile strength, high aspect ratio geometry, and unique electromagnetic characteristics. Their use has also been beneficial for sensor equipment, both terrestrial and space-faring, due to their extremely low photon and electron reflectivity

Suppresion of Electron Yield With Carbon Nanotube Forests: A Case Study

Electron emission of carbon nanotube (CNT) forests grown on silicon substrates was measured to investigate possible electron yield suppression due to the composition and morphology of CNT forests. CNT forests are vertically-oriented tubular formations of graphitic carbon grown on a substrate; these have been widely investigated for their extreme properties in optical, electrical, and mechanical aspects of physics and material sciences. CNT coatings are good candidates for yield reduction, in analogy with the near-ideal blackbody optical properties of CNT forests. Carbon with its low atomic number has an inherent low yield due to its low density of bulk electrons. Furthermore, the large aspect ratio of this vertically-aligned CNT allows for easy penetration of the high energy incident electrons, but enhanced recapture of lower-energy secondary electrons due to their wider angular distribution of emission. Total (TEY), secondary (SEY) and backscattered (BSEY) yield curves using 15 eV to 30 keV electron beams, along with energy emission spectra, were acquired for three CNT forest samples to determine the extent of yield suppression of the substrate due to the CNT forests [Wood, 2018]

Changes to inhaled corticosteroid dose when initiating combination inhaler therapy in long-acting β agonist-naive patients with asthma : a retrospective database analysis

Retrospective prescribing data were obtained from 46 general practice surgeries in NHS Scotland. Patients with asthma who were naïve to previous long-acting β agonist therapy and initiated combination inhaler therapy in 2008–2009 were classified according to the inhaled corticosteroid (ICS) dose in their combination inhaler compared with the highest dose of ICS they received before initiation. Among the 685 patients (541 (79.0%) who had been prescribed an ICS previously), those originally on low-, medium- or high-dose ICS were changed to high-dose combination therapy in 122/250 (48.8%), 94/151 (62.3%) or 85/113 (75.2%) cases in each ICS dose category, respectively. These results suggest that evaluation of appropriate high-dose ICS prescribing in general practice is needed

Sex-based Differences in C. elegans Responsiveness to Aversive Stimuli

Behavioral differences between sexes are evident across many species. The underlying mechanisms surrounding such differences are not fully elucidated, however, due to the complexities of animal behavior. The nematode Caenorhabditis elegans (C. elegans) is a well-characterized, genetically amenable species with two sexes, hermaphrodites (XX) and males (XO). This makes it an appropriate model system for investigating sex-based behavioral differences. Chemosensation in C. elegans is mediated by exposed ciliated sensory neurons, one of which is ASH. ASH is a polymodal nociceptor that elicits reversal when an animal encounters aversive stimuli. We hypothesized that hermaphrodite and male C. elegans worms respond differently to stimuli detected by ASH such as the bitter tastant quinine, the detergent sodium dodecyl sulfate (SDS), and the heavy metal copper (CuCl2). Wild-type assay-age hermaphrodites and males were picked from a nematode growth media (NGM) plate with E. coli OP50 and kept on an NGM plate without food for 10 minutes prior to assaying. A drop of aversive stimulus was placed in front of a forward-moving animal, and the animal’s response was recorded. A positive response is backwards movement within 4 seconds after contact with the stimulus. Our results reveal a quantifiable difference in how wild-type hermaphrodite and male C. elegans respond to aversive stimuli. Specifically, wild-type males are less responsive than hermaphrodites to quinine, SDS, and CuCl2. Further investigations will be conducted through experiments with C. elegans strains in which hermaphrodites have masculinized, and males have feminized nervous systems or subsets of neurons. Through these experiments, we aim to explore potential sites of difference that lead to these observable differences in responsiveness to aversive stimuli

Deuterium Toward WD1634-573: Results from the Far Ultraviolet Spectroscopic Explorer (FUSE) Mission

We use Far Ultraviolet Spectrocopic Explorer (FUSE) observations to study interstellar absorption along the line of sight to the white dwarf WD1634-573 (d=37.1+/-2.6 pc). Combining our measurement of D I with a measurement of H I from Extreme Ultraviolet Explorer data, we find a D/H ratio toward WD1634-573 of D/H=(1.6+/-0.5)e-5. In contrast, multiplying our measurements of D I/O I=0.035+/-0.006 and D I/N I=0.27+/-0.05 with published mean Galactic ISM gas phase O/H and N/H ratios yields D/H(O)=(1.2+/-0.2)e-5 and D/H(N)=(2.0+/-0.4)e-5, respectively. Note that all uncertainties quoted above are 2 sigma. The inconsistency between D/H(O) and D/H(N) suggests that either the O I/H I and/or the N I/H I ratio toward WD1634-573 must be different from the previously measured average ISM O/H and N/H values. The computation of D/H(N) from D I/N I is more suspect, since the relative N and H ionization states could conceivably vary within the LISM, while the O and H ionization states will be more tightly coupled by charge exchange.Comment: 23 pages, 5 figures; AASTEX v5.0 plus EPSF extensions in mkfig.sty; accepted by ApJ Supplemen

Modelling the chromosphere and transition region of Epsilon Eri (K2 V)

Measurements of ultraviolet line fluxes from Space Telescope Imaging Spectrograph and Far-Ultraviolet Spectroscopic Explorer spectra of the K2-dwarf Epsilon Eri are reported. These are used to develop new emission measure distributions and semi-empirical atmospheric models for the chromosphere and lower transition region of the star. These models are the most detailed constructed to date for a main-sequence star other than the Sun. New ionisation balance calculations, which account for the effect of finite density on dielectronic recombination rates, are presented for carbon, nitrogen, oxygen and silicon. The results of these calculations are significantly different from the standard Arnaud & Rothenflug ion balance, particularly for alkali-like ions. The new atmospheric models are used to place constraints on possible First Ionisation Potential (FIP) related abundance variations in the lower atmosphere and to discuss limitations of single-component models for the interpretation of certain optically thick line fluxes.Comment: 22 pages, 9 figure

Discovery of a cataclysmic variable with a sub-stellar companion

We find that the ROSAT source 1RXS J105010.3-140431 is a cataclysmic variable with orbital period of 88.6 minutes and a spectrum closely resembling WZ Sge. In particular, emission lines are flanked by Stark-broadened absorption wings probably originating in the photosphere of a compact object. The Balmer absorption lines can be modeled by the spectrum of a DA white dwarf with 13 000 $< T_{eff} <$ 24 000 K. The strong absorption lines allowed us to obtain direct radial velocities of the white dwarf using the cross-correlation technique. We find an extremely low white dwarf radial velocity half amplitude, $K_{wd}$ = 4 $\pm$ 1 km s$^{-1}$. This is consistent with the upper limit obtained from the H$\alpha$ emission line wing K < 20 km s$^{-1}$. The corresponding mass function is incompatible with a main sequence secondary, but is compatible with a post orbital period minimum cataclysmic variable with a brown dwarf-like secondary. The formal solution gives a secondary mass of 10-20 jovian masses. Doppler maps for the emission lines and the hypothesis of black-body emission indicate a steady state (T $\sim r^{-3/4}$) accretion disk mainly emitting in H$\alpha$ and an optically thicker hotspot with a strong contribution to the higher order Balmer lines and \ion{He}{I} 5875. As in other long cycle length dwarf novae, evidence for inner disk removal is found from the analysis of the emission lines.Comment: 14 figures, 2 of them composed. Total 20 figures. Accepted for publication in Astronomy and Astrophysic