The masses, radii and luminosities of the components of U Geminorum

This is the author accepted manuscript. The final version is available from [publisher] via http://dx.doi.org/10.1111/j.1365-2966.2005.09262.xWe present a phase-resolved spectroscopic study of the secondary star in the cataclysmic variable (CV) U Gem. We use our data to measure the radial velocity semi-amplitude, systemic velocity and rotational velocity of the secondary star. Combining this with literature data allows us to determine masses and radii for both the secondary star and white dwarf, which are independent of any assumptions about their structure. We use these to compare their properties to those of field stars and find that both components follow field mass-radius relationships. The secondary star has the mass, radius, luminosity and photometric temperature of an M2 star, but a spectroscopic temperature of M4. The latter may well be due to a high metallicity. There is a troubling inconsistency between the radius of the white dwarf inferred from its gravitational redshift and inclination and that inferred from its temperature, flux and astrometric distance. We find that there are two fundamental limits to the accuracy of the parameters we can derive. First, the radial velocity curve of the secondary star deviates from a sinusoid, in part because of its asphericity (which can be modelled) and in part because the line flux is not evenly distributed over its surface. Secondly, we cannot be certain which spectral type is the best match for the lines of the secondary star, and the derived rotational velocity is a function of the spectral type of the template star used.The Isaac Newton Telescope is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. We thank Stuart Littlefair for useful discussions, and the referee Robert Smith for a careful reading and useful suggestions. Computing was performed on the Exeter node of the Starlink network, funded by PPARC

The masses, radii and luminosities of the components of U Geminorum

We present a phase-resolved spectroscopic study of the secondary star in the cataclysmic variable U Gem. We use our data to measure the radial velocity semi-amplitude, systemic velocity and rotational velocity of the secondary star. Combining this with literature data allows us to determine masses and radii for both the secondary star and white dwarf which are independent of any assumptions about their structure. We use these to compare their properties with those of field stars and find that both components follow field mass-radius relationships. The secondary star has the mass, radius, luminosity and photometric temperature of an M2 star, but a spectroscopic temperature of M4. The latter may well be due to a high metallicity. There is a troubling inconsistency between the radius of the white dwarf inferred from its gravitational redshift and inclination and that inferred from its temperature, flux, and astrometric distance. We find that there are two fundamental limits to the accuracy of the parameters we can derive. First the radial velocity curve of the secondary star deviates from a sinusoid, in part because of its asphericity (which can be modelled) and in part because the line flux is not evenly distributed over its surface. Second we cannot be certain which spectral type is the best match for the lines of the secondary star, and the derived rotational velocity is a function of the spectral type of the template star used.Comment: 12 pages, 10 figures. Accepted for MNRA

The relationship between individual needs and the choice of incentive schemes in the South African Breweries

After careful review of all the relevant literature pertaining to motivation, performance management and compensation in the form of incentives, this thesis focuses primarily on determining whether a statistically significant relationship exists between individual needs and the choice of an incentive scheme option. The secondary aims of the research are to determine whether: A relationship exists between the job grade of an individual and the choice of an incentive scheme. A particular incentive scheme option is preferred by the employees in The South African Breweries (SAB). A particular preference exists, and if so, to make recommendations to SAB for consideration as alternatives to their existing incentive scheme options. After collation of the survey data from the respondents in the sample, the analysis and discussion of the results determined that no significant relationship exists between individual needs and the choice of an incentive scheme option. It was, however, determined that a significant relationship exists between the grade of the employees in SAB and their choice of an incentive scheme. 81% of all respondents indicated a desire for shares as an option in their Short Term Incentives (STI) which indicates a desire for shares in some form or another and may well indicate a level of confidence and commitment by the employees to the organisation. Although the research hypothesis was not proven, significant insights into remuneration within SAB was obtained, which has resulted in recommendations being made for further research into the option of shares in some form or another in the organisation. A further recommendation for SAB is to consider some form of share options for all employees in the organisation. As many other organisations that are performing at remarkable levels attest this performance to share ownership and the behaviour that emanates from it, it would be in the interests of SAB to further investigate the issue as it may improve performance, ownership and retention within the company

Ferritic nitrocarburising of tool steels

Four different tool steel materials, P20, H13, M2 and D2, were nitrocarburised at 570&deg;C in a fluidised bed furnace. The reactive diffusion of nitrogen and carbon into the various substrate microstructures is compared and related to the different alloy carbide distributions. The effect of carbon bearing gas (carbon dioxide, natural gas) on carbon absorption is reported, as well as its influence on compound layer growth and porosity. Partial reduction of Fe3O4 at the surface resulted in the formation of a complex, epsi-nitride containing oxide layer. In H13, carbon was deeply absorbed throughout the entire diffusion zone, affecting the growth of grain boundary cementite, nitrogen diffusivity and the sharpness of the compound layer: diffusion zone interface. When natural gas was used, carbon became highly concentrated in the compound layer, while surface decarburisation occurred with carbon dioxide. These microstructural effects are discussed in relation to hardness profiles, and compound layer hardness and ductility. The surfaces were characterised using glow discharge optical emission spectroscopy, optical and scanning electron microscopy and X-ray diffraction.<br /

Pin on disc wear investigation of nitrocarburised H13 tool steel

Nitrocarburised H13 disks were tested in dry, sliding wear against a stationary ruby ball (pin). Three different 4 h nitrocarburising treatments were compared, using N2/NH3/CO2, N2/NH3/natural gas and N2/NH3 gas mixtures, resulting in compound layers of varying thickness, hardness, porosity and oxide morphology. During mild, oxidative wear, with the formation of abrasive wear debris, the most brittle and oxidised surfaces performed poorly. Polishing to a bright, reflective finish greatly reduced wear. However, the N2/NH3/CO2 sample also frequently maintained a \u27very mild\u27 wear regime, owing to the formation of a protective film between the wear surfaces, and resulting in a lowering of the friction coefficient. This treated surface was porous and covered in a complex layer of coarse oxide+epsi-carbonitride. Nitrocarburised samples and wear tracks were characterised by optical microscopy, SEM, atomic force microscopy and stylus profilometry.<br /

Change of Magnetic Properties of Th₂Fe₁₇ Due to Interstitial Solution of C and N

The changes in magnetic and crystallographic properties in the series Th2Fe17Cx and Th2Fe 17Nx have been studied. The changes in the latter series were also studied by 57Fe Mössbauer spectroscopy. The ultimate enhancements of the saturation moments in these series are 13% and 24%, respectively. This is much larger than observed previously in the corresponding rare-earth compounds, although the Curie temperature enhancements are of comparable magnitude. In the Th-Fe-C system a novel compound of the BaCd 11 type was found, having a Curie temperature around 370 K

Transmission-blocking activity induced by malaria vaccine candidates Pfs25/Pvs25 is a direct and predictable function of antibody titer

<p>Abstract</p> <p>Background</p> <p>Mosquito stage malaria vaccines are designed to induce an immune response in the human host that will block the parasite's growth in the mosquito and consequently block transmission of the parasite. A mosquito membrane-feeding assay (MFA) is used to test transmission-blocking activity (TBA), but in this technique cannot accommodate many samples. A clear understanding of the relationship between antibody levels and TBA may allow ELISA determinations to be used to predict TBA and assist in planning vaccine development.</p> <p>Methods</p> <p>Rabbit anti-Pfs25 sera and monkey anti-Pvs25 sera were generated and the antibody titers were determined by a standardized ELISA. The biological activity of the same sera was tested by MFA using <it>Plasmodium </it>gametocytes (cultured <it>Plasmodium falciparum </it>or <it>Plasmodium vivax </it>from malaria patients) and <it>Anopheles </it>mosquitoes.</p> <p>Results</p> <p>Anti-Pfs25 and anti-Pvs25 sera showed that ELISA antibody units correlate with the percent reduction in the oocyst density per mosquito (Spearman Rank correlations: 0.934 and 0.616, respectively), and fit a hyperbolic curve when percent reduction in oocyst density is plotted against antibody units of the tested sample. Antibody levels also correlated with the number of mosquitoes that failed to become infected, and this proportion can be calculated from the reduction in oocyst numbers and the distribution of oocysts per infected mosquito in control group.</p> <p>Conclusion</p> <p>ELISA data may be used as a surrogate for the MFA to evaluate transmission-blocking vaccine efficacy. This will facilitate the evaluation of transmission-blocking vaccines and implementation of this malaria control strategy.</p

Semantic segmentation and photogrammetry of crowdsourced images to monitor historic facades

Crowdsourced images hold information could potentially be used to remotely monitor heritage sites, and reduce human and capital resources devoted to on-site inspections. This article proposes a combination of semantic image segmentation and photogrammetry to monitor changes in built heritage sites. In particular, this article focuses on segmenting potentially damaging plants from the surrounding stone masonry and other image elements. The method compares different backend models and two model architectures: (i) a one-stage model that segments seven classes within the image, and (ii) a two-stage model that uses the results from the first stage to refine a binary segmentation for the plant class. The final selected model can achieve an overall IoU of 66.9% for seven classes (54.6% for one-stage plant, 56.2% for two-stage plant). Further, the segmentation output is combined with photogrammetry to build a 3D segmented model to measure the area of biological growth. Lastly, the main findings from this paper are: (i) With the help of transfer learning and proper choice of model architecture, image segmentation can be easily applied to analyze crowdsourcing data. (ii) Photogrammetry can be combined with image segmentation to alleviate image distortions for monitoring purpose. (iii) Beyond the measurement of plant area, this method has the potential to be easily transferred into other tasks, such as monitoring cracks and erosion, or as a masking tool in the photogrammetry workflow

The Ursinus Weekly, May 21, 1909

Brotherhood of St. Paul fletcherizes • Buffalo Bill in Philadelphia • Malcolm Shackelford entertains audience • Glee club • Lecture • Baseball • Ursinus Union • Tennis tournament • Society notes • Alumni notes • Personals • Field house fund • Literary Supplement: A day in May; The power of sentiment; A generation of vipers; Literary criticism on Tolstoy; The power of ideas; Money and hypocrisyhttps://digitalcommons.ursinus.edu/weekly/2873/thumbnail.jp