7,478 research outputs found

    Transfer Function Approximations for Large Highly Coupled Elastic Boosters with Fuel Slosh

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    Transfer function approximations for large highly coupled flexible body launch vehicles with liquid fuel slos

    Eumops perotis.

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    Eumops perotis is the largest bat in the United States. The greater mastiff bat resembles other North American free-tailed bats, but is distinguished from other molossids by its large size and lack of long guard hairs on the rump (Barbour and Davis, 1969). E. perotis has the thinnest dentary of any Eumops (Freeman, 1981a).In the United States, E. perotis can be separated from E. underwoodi by its larger size (forearm is 73-83 mm in E. perotis and 65-77 mm in E. underwoodi), darker color, and lack of long guard hairs on the rump. The ears are longer (36-47 mm in E. perotis and 28-32 mm in E. underwoodi), they extend beyond the nose when laid forward, and they are joined at the midline. In E. perotis, the tragus is large, broad, and square, the greatest length of the skull usually is \u3e30 mm rather than less, the basisphenoid pits are large, deep, and not oval shaped, and the third transverse commissure of the M3 hardly is discernible (Barbour and Davis, 1969; Hoffmeister, 1986). Compared with E. perotis, the skull of E. underwoodi (Fig. 2) is shorter, wider, and less robust, and the interorbital region is distinctly hourglass-shaped rather than nearly cylindrical as in E. perotis (Benson, 1947). Compared with E. perotis, E. dabbenei has shorter ears, smaller pointed tragus, more massive skull, and the basisphenoid pits are shallower and less developed (Eger, 1977)

    Optimising the ingredients for evaluation of the effects of intervention

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    Background: In Howard, Best and Nickels (2015, this issue) we presented a set of ideas relevant to the design of single case studies for evaluation of the effects of intervention. These were based on experience with intervention research, methodological expertise and a set of simulations. Our discussion and conclusions were not intended as guidelines (of which there are several in the field) but rather had the aim of stimulating debate and optimising designs in the future. Our paper achieved the first aim - it received a set of varied commentaries, not all of which felt we were optimising designs, and which raised further points for debate. Aims: In this paper, respond to the commentaries, and examine the guidelines for evaluation of the design of single case studies proposed by Tate, Perdices, Rosenkoetter, Wakim, Godbee, Togher & McDonald (2013). We aim to further the discussion our target article has started and extend the scope more broadly to issues that were not discussed in our target article (e.g. replication) Main Contributions & Conclusions: It is clear that there is a strong consensus that adequately designed single case studies of intervention are an appropriate and important tool in our quest for effective interventions with people with cognitive disorders. It is also the case that many agree that there is no single design that is appropriate for every intervention, every participant or every question. However, whichever design is used it must be able to discriminate between the true effect of an intervention on behaviour, and other potential reasons for change (e.g. practice effects, spontaneous recovery, Hawthorne effects, placebo effects). We have suggested that, depending on the conditions and question to be addressed, this can be achieved using a combination of design features. These may include: multiple pre-treatment baselines, treated and untreated (or subsequently treated) items/processes/tasks, control tasks (not predicted to be affected by treatment even when generalisation is expected), and a cross-over phase (replication across items/tasks). In addition, the outcome of treatment should be evaluated statistically. We note that generalisation which is clinically desirable, can lead to particular difficulties in attributing change to intervention unless appropriate controls have been included, and that when items are selected on the basis of poor pre-treatment performance, apparent treatment-related gains may in fact be due to regression to the mean and discuss the implications of this for future research

    The Active Nucleus of IC4970: A Nearby Example of Merger-Induced Cold-Gas Accretion

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    We present results from Chandra X-ray and Spitzer mid-infrared observations of the interacting galaxy pair NGC6872/IC4970 in the Pavo galaxy group and show that the smaller companion galaxy IC4970 hosts a highly obscured active galactic nucleus (AGN). The 0.5-10 keV X-ray luminosity of the nucleus is variable, increasing by a factor 2.9 to 1.7 x 10^{42} erg/s (bright state) on ~100 ks timescales. The X-ray spectrum of the is heavily absorbed (N_H = 3 x 10^{23} cm^{-2}) for power law models with Gamma = 1.5-2.0 and shows a clear 6.4 keV Fe Kalpha line with equivalent width of 144-195 eV. Limits on the diffuse emission in IC4970 from Chandra X-ray data suggest that the available power from Bondi accretion of hot interstellar gas may be an order of magnitude too small to power the AGN. Spitzer images show that 8 micron nonstellar emission is concentrated in the central 1 kpc of IC4970, consistent with high obscuration in this region. The mid-infrared colors of the nucleus are consistent with those expected for a highly obscured AGN. Taken together these data suggest that the nucleus of IC4970 is a Seyfert 2, triggered and fueled by cold material supplied to the central supermassive black hole as a result of the off-axis collision of IC4970 with the cold-gas rich spiral galaxy NGC6872.Comment: 10 pages, 9 figures, submitted to ApJ, MIR flux conversion error corrected in Table 4, MIR colors and paper text unchange

    Understanding differing outcomes from semantic and phonological interventions with children with word-finding difficulties: a group and case series study

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    Developmental Language Disorder occurs in up to 10% of children and many of these children have difficulty retrieving words in their receptive vocabulary. Such word-finding difficulties (WFD) can impact social development and educational outcomes. This research aims to develop the evidence-base for supporting children with WFD and inform the design and analysis of intervention studies. We included 20 children (age 6 to 8) with WFD each of whom participated in two interventions one targeting semantic attributes and the other phonological attributes of target words. The interventions, employing word-webs, were carefully constructed to facilitate direct comparison of outcome which was analysed at both group and case-series level. The study used a robust crossover design with pre-intervention baseline, between–intervention wash-out and post-intervention follow-up testing. We incorporated: matching of item sets on individual performance at baseline, independent randomisation of order of intervention and items to condition, blinding of assessor, evaluation of fidelity and control items. The interventions were clinically feasible, with weekly sessions over six weeks. Intervention improved children’s word-finding abilities with statistically significant change only during treatment phases of the study and not over baseline, wash-out or follow-up phases. For the group the semantic intervention resulted in a gain of almost twice as many items as the phonological intervention, a significant difference. However, children differed in their response to intervention. Importantly, case-series analysis revealed outcomes predictable on the basis of children’s theoretically driven language profiles. Taking account of individual profiles in determining choice of intervention would enable more children to benefit. The study provides new evidence to inform and refine clinical practice with this population. Future studies should be designed such that results can be analysed at both group and case series levels to extend theoretical understanding and optimise use of appropriate interventions

    Double Lobed Radio Quasars from the Sloan Digital Sky Survey

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    We have combined a sample of 44984 quasars, selected from the Sloan Digital Sky Survey (SDSS) Data Release 3, with the FIRST radio survey. Using a novel technique where the optical quasar position is matched to the complete radio environment within 450", we are able to characterize the radio morphological make-up of what is essentially an optically selected quasar sample, regardless of whether the quasar (nucleus) itself has been detected in the radio. About 10% of the quasar population have radio cores brighter than 0.75 mJy at 1.4 GHz, and 1.7% have double lobed FR2-like radio morphologies. About 75% of the FR2 sources have a radio core (> 0.75 mJy). A significant fraction (~40%) of the FR2 quasars are bent by more than 10 degrees, indicating either interactions of the radio plasma with the ICM or IGM. We found no evidence for correlations with redshift among our FR2 quasars: radio lobe flux densities and radio source diameters of the quasars have similar distributions at low (mean 0.77) and high (mean 2.09) redshifts. Using a smaller high reliability FR2 sample of 422 quasars and two comparison samples of radio-quiet and non-FR2 radio-loud quasars, matched in their redshift distributions, we constructed composite optical spectra from the SDSS spectroscopic data. Based on these spectra we can conclude that the FR2 quasars have stronger high-ionization emission lines compared to both the radio quiet and non-FR2 radio loud sources. This is consistent with the notion that the emission lines are brightened by ongoing shock ionization of ambient gas in the quasar host as the radio source expands.Comment: 20 pages, 10 figures - some of which have been reduced in quality / size. Accepted for publication in the Astronomical Journa

    Extended Emission Line Gas in Radio Galaxies - PKS0349-27

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    PKS0349-27 is a classical FRII radio galaxy with an AGN host which has a spectacular, spiral-like structure in its extended emission line gas (EELG). We have measured the velocity field in this gas and find that it splits into 2 cloud groups separated by radial velocities which at some points approach 400 km/s Measurements of the diagnostic emission line ratios [OIII]5007/H-beta, [SII]6716+6731/H-alpha, and [NII]6583/H-alpha in these clouds show no evidence for the type of HII region emission associated with starburst activity in either velocity system. The measured emission line ratios are similar to those found in the nuclei of narrow-line radio galaxies, but the extended ionization/excitation cannot be produced by continuum emission from the active nucleus alone. We present arguments which suggest that the velocity disturbances seen in the EELG are most likely the result of a galaxy-galaxy collision or merger but cannot completely rule out the possibility that the gas has been disrupted by the passage of a radio jet.Comment: 12 pages, 3 fig pages, to appear in the Astrophys.

    Star Formation, Radio Sources, Cooling X-ray Gas, and Galaxy Interactions in the Brightest Cluster Galaxy in 2A0335+096

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    We present deep emission-line imaging taken with the SOAR Optical Imaging Camera of the brightest cluster galaxy (BCG) in the nearby (z=0.035) X-ray cluster 2A0335+096. We analyze long-slit optical spectroscopy, archival VLA, Chandra X-ray, and XMM UV data. 2A0335+096 is a bright, cool-core X-ray cluster, once known as a cooling flow. Within the highly disturbed core revealed by Chandra X-ray observations, 2A0335+096 hosts a highly structured optical emission-line system. The redshift of the companion is within 100 km/s of the BCG and has certainly interacted with the BCG, and is likely bound to it. The comparison of optical and radio images shows curved filaments in H-alpha emission surrounding the resolved radio source. The velocity structure of the emission-line bar between the BCG nucleus and the companion galaxy provides strong evidence for an interaction between the two in the last ~50 Myrs. The age of the radio source is similar to the interaction time, so this interaction may have provoked an episode of radio activity. We estimate a star formation rate of >7 solar mass/yr based on the Halpha and archival UV data, a rate similar to, but somewhat lower than, the revised X-ray cooling rate of 10-30 solar masses/year estimated from XMM spectra by Peterson & workers. The Halpha nebula is limited to a region of high X-ray surface brightness and cool X-ray temperature. The detailed structures of H-alpha and X-ray gas differ. The peak of the X-ray emission is not the peak of H-alpha emission, nor does it lie in the BCG. The estimated age of the radio lobes and their interaction with the optical emission-line gas, the estimated timescale for depletion and accumulation of cold gas, and the dynamical time in the system are all similar, suggesting a common trigger mechanism.Comment: Accepted AJ, July 2007 publication. Vol 134, p. 14-2
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