1,082 research outputs found

    A spectroscopic study of LMC X-4

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    The orbital radial velocity semi-amplitude of the binary star system LMC X-4 primary was determined to be 37.9 + or - 2.4 km/s from measurements of the hydrogen absorption lines. The semi-amplitude of the He I and He II absorption lines are consistent with this, namely 44.9 + or - 5.0 and 37.3 + or - 5.3 km/s. The phase and shape of the radial velocity curves of the three ions are consistent with a circular orbit and an ephemeris based upon X-ray measurements of the neutron star, with the exception that the He II absorption line radial velocity curve has detectable shape distortion. Measurements of the He II LAMBOA 4686 emission line velocity are consistent with a phase shifted sine wave of semi-amplitude 535 km/s, a square wave of semi-amplitude 407 km/s, or high order harmonic fits. The spectral type was found to be 08.5 IV-V during X-ray eclipse. Variations to types as early as 07 occur, but not as a function or orbital phase. Absorption line peculiarities were noted on 6 of 58 spectra

    Eye Tracking Food Cues in Subjects who are Overweight/Obese, Weight Loss Maintainers, and Normal Weight

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    Adult obesity is associated with increased morbidity and mortality. Increasing success in weight loss maintenance will decrease the prevalence of overweight and obesity, and therefore help control the adverse health effects of excess weight. Much is known about the behavioral characteristics of successful long-term weight loss maintenance, but less is known about the cognitive processes behind weight loss maintenance. The purposes of this study were to (1) identify differences in visual attention to high-energy dense foods between individuals who are normal weight, weight loss maintainers, and overweight/obese in a high-risk (food-buffet) situation; (2) to evaluate differences in food choices from a food buffet between weight status groups; (3) to analyze correlations between food attention and food choice across weight status groups. No significant differences were found between groups with respect to food attention or food choice. Overall, findings from this study may have been limited by methodology, technology, and sample size. Future research is needed to better understand the interaction of cognitive processes and weight loss maintenance

    Research On Maximizing Critical And Reducing Initial Heat Flux Densities To Eliminate Any Film Boiling And Minimize Distortion During Quenching

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    In the paper the results of testing three types of FUCHS oils: Thermisol QH 120, Thermisol QH 10 and Thermisol QB 46 are discussed. The main attention is paid to critical heat flux densities evaluation because they create a basis for optimizing cooling intensity of any liquid quenchant. In the paper is underlined that any film boiling during quenching is undesirable since it is a reason for big distortion and non-uniform surface harness. It is shown that intensive quenching decreases distortion of steel parts during quenching. To eliminate film boiling during quenching in mineral oils, optimal temperature of oil should be chosen which maximize the first critical heat flux density and special additives should be used to decrease initial heat flux by creating surface micro-coating. Along with the evaluation of heat transfer coefficients, critical heat flux densities inherent to liquid quenchant must be measured first to optimize quenching processes. International DATABASE on cooling characteristics of liquid quenchants must include critical heat flux densities, initial heat flux densities, and heat transfer coefficients allowing optimizing and governing quenching processes

    Mechanics and Mathematical Modeling of Class III Treatment with Orthodontic Appliances with a Movable Ramp

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    Treatment of class III is a current problem in orthodontics that requires constant improvement of its methods, development of new or modifications of known methods and techniques. We have developed and studied the modification of removable functionally-directing orthodontic appliances for treatment of Class III, which consists of a plastic base, vestibular arc, retaining clasps, ramp, which is connected with the base by means of two torsion springs. Its usage ensures a prolonged contact of ramp with the teeth. We studied two types of club-shaped springs (torsion springs): one spring, which create an amortization effect during the action of the ramp, but do not change its inclination angle and second one – spring that seek to increase the angle of the ramp inclination due to the disclosure of its curl

    Susceptibility of Eucalyptus Species and Clones to Red Gum Lerp Psyllid, Glycaspis brimblecombei, (Hemiptera: Psyllidae) in Mbizi Forest Plantation, Tanzania

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    Glycaspis brimblecombei is a sap-sucking insect that feeds on Eucalypts. The pest is native to Australia. The nymph feeds on eucalypt leaves and secretes honeydew with which they construct a waxy cover (called a lerp) around themselves. This cover is whitish and conical in shape and shelters the insects until the adult stage. The insect is considered a serious pest that causes leaf discoloration, severe leaf drop, twig dieback and some tree mortality on some Eucalyptus species. In October 2016, the red gum lerp psyllid was recorded for the first time in Mbizi forest plantation in Tanzania infesting Eucalyptus camaldulensis and different Eucalyptus clones. A study was conducted to determine the susceptibility of Eucalypt germplasm to the insect pest. Results showed that E. camaldulensis was more infested followed by GC 514, GC 167, GC 584, GC 15, GC 785 clones while GC 940 was the least infested. Eucalyptus grandis was not infested. Stakeholders can be able to use the susceptibility grouping of the Eucalyptus germplasm to determine what to plant in areas of red gum lerp psyllid infestation. Similar research work should be carried in all major host tree growing areas to determine susceptibility groups for the areas

    A Search for Planets Transiting the M Dwarf Debris Disk Host, AU Microscopii

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    We present high cadence, high precision multi-band photometry of the young, M1Ve, debris disk star, AU Microscopii. The data were obtained in three continuum filters spanning a wavelength range from 4500\AA to 6600\AA, plus Hα\alpha, over 28 nights in 2005. The lightcurves show intrinsic stellar variability due to starspots with an amplitude in the blue band of 0.051 magnitudes and a period of 4.847 days. In addition, three large flares were detected in the data which all occur near the minimum brightness of the star. We remove the intrinsic stellar variability and combine the lightcurves of all the filters in order to search for transits by possible planetary companions orbiting in the plane of the nearly edge-on debris disk. The combined final lightcurve has a sampling of 0.35 minutes and a standard deviation of 6.8 millimags (mmag). We performed Monte Carlo simulations by adding fake transits to the observed lightcurve and find with 95% significance that there are no Jupiter mass planets orbiting in the plane of the debris disk on circular orbits with periods, P ≤5\le 5 days. In addition, there are no young Neptune-like planets (with radii 2.5×\times smaller than the young Jupiter) on circular orbits with periods, P ≤3\le 3 days.Comment: accepted to MNRA

    Case History Illustrating the Challenges of Foundation Design and Construction in Karst Terrain

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    This paper discusses the challenges associated with design and construction of foundation systems for a Corporate Campus located in Chester County, Pennsylvania that is underlain by Karst terrain. A comprehensive subsurface investigation was implemented to develop adequate foundation systems and related site work precautions. Because there was evidence of sinkhole activity prior to any construction work, and the subsoils revealed some variability from a consistency/density standpoint, the selected foundation system design included a combination of soil improvement using compaction grouting for shallow foundations and deep drilled-pier foundations. After construction activities began, several occurrences of solution activity were documented and repaired. During construction of drilled-pier foundations at one of the structure locations, a significant number of voids and discontinuities in the rock were encountered. The impact of these discontinuities and voids was dramatic to the effort and time necessary to complete the drilled pier foundation construction for this structure. After careful consideration of potential cost and schedule impacts, the foundation design for remaining structures was modified to eliminate the use of drilled piers and incorporated only compaction grouting for support of shallow foundation systems. Interaction of the Geotechnical Engineer, Construction Manager, Owner, and Contractor began early in the construction process and this interaction became critical to the project success as work proceeded on this project

    Bi-log-concave distribution functions

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    Nonparametric statistics for distribution functions F or densities f=F' under qualitative shape constraints provides an interesting alternative to classical parametric or entirely nonparametric approaches. We contribute to this area by considering a new shape constraint: F is said to be bi-log-concave, if both log(F) and log(1 - F) are concave. Many commonly considered distributions are compatible with this constraint. For instance, any c.d.f. F with log-concave density f = F' is bi-log-concave. But in contrast to the latter constraint, bi-log-concavity allows for multimodal densities. We provide various characterizations. It is shown that combining any nonparametric confidence band for F with the new shape-constraint leads to substantial improvements, particularly in the tails. To pinpoint this, we show that these confidence bands imply non-trivial confidence bounds for arbitrary moments and the moment generating function of F

    What Do Nectaris Basin Impact Melt Rocks Look like and Where Can We Find Them?

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    The formation of the Nectaris basin is a key event defining the stratigraphy of the Moon. Its absolute age, therefore, is a linchpin for lunar bombardment history. Fernandes et al. gave a thorough account of the history of different samples thought to originate in Nectaris, with the upshot being there is little agreement on what samples represent Nectaris, if any. We are revisiting the effort to identify Nectaris basin impact-melt rocks at the Apollo 16 site, to model their emplacement, and to use these parameters to examine other sites where Nectaris impact melt is more abundant and/or more recognizable for potential further study
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