3,630 research outputs found
A Look at Philosophical Analysis
No full textThe author of this article, Dr. Ralph L. Pounds, is the author of many books and a Professor of Education at the University of Cincinnati. This article was first given as the presidential address of the Ohio Valley Philosophy of Education Society
The rapid X-ray variability of NGC 4051
No full textWe present an analysis of the high-frequency X-ray variability of NGC 4051 (MBH ~ 1.7 × 106 M⊙) based on a series of XMM–Newton observations taken in 2009 with a total exposure of ~570 ks (EPIC pn). These data reveal the form of the power spectrum over frequencies from 10-4 Hz, below the previously detected power spectral break, to ≥10-2 Hz, above the frequency of the innermost stable circular orbit (ISCO) around the black hole (νISCO ~ 10-3 to 10-2 Hz, depending on the black hole spin parameter j ). This is equivalent to probing frequencies of ≥1 kHz in a stellar mass (MBH ~ 10 M⊙) black hole binary system. The power spectrum is a featureless power law over the region of the expected ISCO frequency, suggesting no strong enhancement or change in the variability at the fastest orbital period in the system. Despite the huge amplitude of the flux variations between the observations (peak-to-peak factor of ≥50), the power spectrum appears to be stationary in shape and varies in amplitude at all observed frequencies following the previously established linear rms–flux relation. The rms–flux relation is offset in flux by a small and energy-dependent amount. The simplest interpretation of the offset is in terms of a very soft spectral component that is practically constant (compared to the primary source of variability). One possible origin for this emission is a circumnuclear shock energized by a radiatively driven outflow from the central regions and emitting via inverse-Compton scattering of the central engine’s optical–UV continuum (as inferred from a separate analysis of the energy spectrum). A comparison with the power spectrum of a long XMM–Newton observation taken in 2001 gives only weak evidence for non-stationarity in power spectral shape or amplitude. Despite being among the most precisely estimated power spectra for any active galaxy, we find no strong evidence for quasi-periodic oscillations (QPOs) and determine an upper limit on the strength of a plausible QPO of ≤2 per cent rms in the 3 × 10-3 to 0.1 Hz range and ~5–10 per cent in the 10-4 to 3 × 10-3 Hz range. We compare these results to the known properties of accreting stellar mass black holes in X-ray binaries, with the further aim of developing a ‘black hole unification’ scheme.<br/
BIOINFORMATICS Sample Size Determination for the False Discovery Rate
No full textMotivation There is not a widely applicable method to determine the sample size for experiments basing statistical significance on the false discovery rate (FDR). Results We propose and develop the anticipated false discovery ratio (aFDR) as a conceptual tool for determining sample size. We derive mathematical expressions for the aFDR and anticipated average statistical power. These expressions are used to develop a general algorithm to determine sample size. We provide specific details on how to implement the algorithm for a k-group (k ≥ 2) comparisons. The algorithm performs well for k-group comparisons in a series of traditional simulations and in a real data simulation conducted by resampling from a large, publicly available data set. Availability Documented S-plus and R code libraries are freely available from www.stjuderesearch.org/depts/biostats. Contact: Stan Pounds
A simultaneous XMM-Newton and BeppoSAX observation of the archetypal broad line Seyfert 1 galaxy NGC 5548
No full textWe report the spectral analysis of a long XMM-Newton observation of the well-studied, moderate luminosity broad line Seyfert 1 galaxy NGC 5548. The source was at an historically average brightness and we find the hard (3-10 keV) spectrum can be well fitted by a power law of photon index Gammasimilar to1.75, together with reflection. The only feature in the hard X-ray spectrum is a narrow emission line near 6.4 keV, with an equivalent width of similar to60 eV. The energy and strength of this line are consistent with fluorescence from 'neutral' iron distant from the central continuum source. We find no evidence for a broad Fe K line, with an upper limit well below previous reports, suggesting the inner accretion disc is now absent or highly ionized. The addition of simultaneous BeppoSAX data allows the analysis to be extended to 200 keV, yielding important constraints on the total reflection. Extrapolation of the hard X-ray power law down to 0.3 keV shows a clear 'soft excess' below similar to0.7 keV. After due allowance for the effects of a complex warm absorber, measured with the XMM-Newton RGS, we find that the soft excess is better described as a smooth upward curvature in the continuum flux below similar to2 keV. The soft excess can be modelled either by Comptonized thermal emission or by enhanced reflection from the surface of a highly ionized disc
Progesterone treatment of anovulatory mares
No full textThis study took place over a 3 year period and was conducted in 4 phases. In total, 40 mares of stock horse type were used. All mares were in good health, but had failed to conceive or did not give birth to a live foal from the preceding year's breeding. In phase one, 6 mares were separated in to 3 groups of 2 mares each. Each group received an intramuscular injection of 17-hydroxyprogesterone-n-caproate (17-OHPC), Delalutin. Group I received 125 mg; group II, 250 mg and group III, 375 mg of 17-OHPC. The results were not conclusive. In phase two, 9 mares were randomly divided in to 3 groups of 3 mares each. Group I received 20 mg; group II, 30 mg; and group III, 40 mg of 17-0HPC per 100 pounds body weight. The treatment groups did not differ significantly in number of days in estrus, number of days from ovulation to the next 3 cm follicle, number of days from a 3 cm follicle to ovulation, or conception rate. When the data accumulated from the treated groups were compared to similar data recorded from normal mares a significant difference (P <0.05) was calculated for the number of days from ovulation to the next 3 cm follicle, with the mean time being 7 days less for the treated mare is. In phase three, 15 mares were randomly divided in to 3 groups of 5 mares each. Group I received 40 mg of 17-OHPC per 100 pounds body weight, group II received 20 mg of 17-OHPC per 100 pounds body weight, and group III was designated as the control. There were no significant differences between groups for number of days in estrus. ..
An extended XMM–Newton observation of the Seyfert galaxy NGC 4051 – III. Fe K emission and absorption
No full textAn extended XMM–Newton observation of the Seyfert 1 galaxy NGC 4051 in 2009 detected a photoionized outflow with a complex absorption-line velocity structure and a broad correlation of velocity with ionization parameter, shown by Pounds & Vaughan to be consistent with a highly ionized, high-velocity wind running into the interstellar medium or previous ejecta, losing much of its kinetic energy in the resultant strong shock. In this paper, we examine the Fe K spectral region in more detail and find support for two distinct velocity components in the highly ionized absorber, with values corresponding to the putative fast wind (∼0.12c) and the post-shock flow (v∼ 5000–7000 km s[Superscript: −1]). The Fe K absorption-line structure is seen to vary on a orbit-to-orbit time-scale, apparently responding to both a short-term increase in ionizing flux and – perhaps more generally – to changes in the soft X-ray (and simultaneous ultraviolet) luminosity. The latter result is particularly interesting in providing independent support for the existence of shocked gas being cooled primarily by Compton scattering of accretion disc photons. The Fe K emission is represented by a narrow fluorescent line from near-neutral matter, with a weak red wing modelled here by a relativistic diskline. The narrow line flux is quasi-constant throughout the 45-d 2009 campaign, but is resolved, with a velocity width consistent with scattering from a component of the post-shock flow. Evidence for a P Cygni profile is seen in several individual orbit spectra for resonance transitions in both Fe xxv and Fe xxvi
Effect of feeding yearling steers on bluestem pasture 2 pounds of corn or soybean pellets during the latter part of the grazing season.
No full textThirty-six head of good quality yearling Hereford steers were used
in this test. They had been grazing together on bluestem pasture previous
to the test. The steers were divided into three lots of 12 steers
each, in a manner to equalize any difference due to previous winter
treatments. They were grazed on bluestem pasture and received the
following treatment from August 6, 1953, to October 23, 1953.
Lot I-No supplement.
Lot 2-Two pounds of soybean pellets per head daily.
Lot 3-Two pounds of corn per head daily.
The steers were rotated on the pastures every 15 days to equalize
any differences that might be due to pastures
Patient-centred communication in Ask-the-expert healthcare websites
No full textThe study presented in this article explores to what extent and in what ways the communication between clinicians and patients on Ask-the-Expert healthcare websites is patient-centred. It further demonstrates the value of using a theory- and text-driven discourse analytical approach for the analysis of verbal communication in a (specific health) professional domain. The UK website Netdoctor is used as a case study. Thirty exchanges from this site, on the topic of depression, were analysed using a discourse-pragmatic framework, drawing on existing theories and definitions of patient-centred communication (PCC), a classification of empathic communication acts (Pounds 2011) and existing research on advice-giving in online communication. The analysis shows that, overall, experts make wide use of PCC, particularly empathic expression, in their online responses. The author concludes that there is a high potential for the expression of PCC on Ask-the-Expert health sites and that this may be more or less exploited, depending on the restrictions imposed on the contributors by the site managers and users’ expectation
Diagnostic strategies using DNA testing for hereditary haemochromatosis in at-risk populations: a systematic review and economic evaluation
No full textOBJECTIVE: To evaluate DNA testing for detecting hereditary haemochromatosis (HHC) in subgroups of patients suspected of having the disorder and in family members of those diagnosed with HHC. DATA SOURCES: Major electronic databases, searched from inception to April 2007. REVIEW METHODS: A systematic review was undertaken using a priori methods and a de novo model developed to assess costs and consequences of DNA testing. RESULTS: Eleven studies were identified for estimating the clinical validity of genotyping for the C282Y mutation for the diagnosis of HHC. No clinical effectiveness studies meeting the inclusion criteria were identified. Two North American cost-effectiveness studies of reasonable quality were identified but their generalisability to the UK is not clear. Three cohort studies met the inclusion criteria for the review of psychosocial aspects. All had methodological limitations and their generalisability is difficult to determine. The clinical sensitivity of C282Y homozygosity for HHC ranged from 28.4% to 100%, or from 91.3% to 92.4% when considering only the most relevant studies. Clinical specificity ranged from 98.8% to 100%. One study found that gene testing was a cost-effective method of screening relatives of patients with haemochromatosis, whereas the other found that genotyping the spouse of a homozygote was the most cost-efficient strategy. Genetic testing for haemochromatosis appears to be well accepted, is accompanied by few negative psychosocial outcomes and may lead to reduced anxiety. The de novo economic model showed that, in people suspected of having haemochromatosis, the DNA strategy is cost saving compared with the baseline strategy using liver biopsy (cost saved per case detected 123 pounds), largely because of the reduction in liver biopsies. For family testing of siblings the DNA strategy is not cost saving because of the costs of the DNA test (additional cost per case detected 200 pounds). If the cost of the test were to reduce from 100 pounds to 60 pounds, the DNA strategy would be the cheaper one. For family testing of offspring the DNA test strategy is cheaper than the baseline biochemical testing strategy (cost saved per case detected 7982 pounds). Sensitivity analyses showed that the conclusions in each case are robust across all reasonable parameter values. CONCLUSIONS: The preferred strategy in practice is DNA testing in conjunction with testing iron parameters when there is clear clinical indication of risk for haemochromatosis because of biochemical criteria or when there is familial risk for HHC. Access to genetic testing and centralisation of test provision in expert laboratories would lower the cost of testing, improve the cost-effectiveness of the strategy and improve the quality of information provided to clinicians and patients.<br/
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