UCDs as Probes of the Major and Minor Merger Histories of Galaxies

Two competing theories posit that Ultra Compact Dwarfs (UCDs) form either as the stripped nuclei of dwarf galaxies or as giant globular clusters (GGCs) associated with the largest globular cluster (GC) systems. By focussing on the field and group environments where young UCDs may be most common, we have discovered the first UCD that is clearly the result of recent (<4 Gyr ago) stripping of a companion galaxy. However, we have also found a definitive case of a multiple-UCD system created via GC formation processes, which are likely associated with major galaxy mergers. We demonstrate that it is possible to reliably distinguish the two types of UCD, thereby probing both the major and minor merger histories of individual galaxies.Comment: 2 pages, 1 figure, to appear in the proceedings of the conference "A Universe of Dwarf Galaxies" (Lyon, June 14-18, 2010

On the survivability and detectability of terrestrial meteorites on the moon

Materials blasted into space from the surface of early Earth may preserve a unique record of our planet's early surface environment. Armstrong et al. (2002) pointed out that such materials, in the form of terrestrial meteorites, may exist on the Moon and be of considerable astrobiological interest if biomarkers from early Earth are preserved within them. Here, we report results obtained via the AUTODYN hydrocode to calculate the peak pressures within terrestrial meteorites on the lunar surface to assess their likelihood of surviving the impact. Our results confirm the order-of-magnitude estimates of Armstrong et al. (2002) that substantial survivability is to be expected, especially in the case of relatively low velocity (ca. 2.5 km/s) or oblique (≤45°) impacts, or both. We outline possible mechanisms for locating such materials on the Moon and conclude that searching for them would be a scientifically valuable activity for future lunar exploration

Role of carbon dioxide and ion transport in the formation of sub-embryonic fluid by the blastoderm of the Japanese quail

1. The explanted blastoderm of the Japanese quail was used to explore the role of ions and carbon dioxide in determining the rate of sub-embryonic fluid (SEF) production between 54 and 72 h of incubation. 2. Amiloride, an inhibitor of Na+/H+ exchange, at concentrations of 10-3 to 10-6 M substantially decreased the rate of SEF production when added to the albumen culture medium. N-ethylmaleimide, an inhibitor of V type H+ ATPase, also decreased this rate but only to a small extent at the highest dose applied, 10-3 M. Both inhibitors had no effect on SEF production when added to the SEF. 3. The inhibitors of cellular bicarbonate and chloride exchange, 4-acetamido-4-'isothiocyano-2, 2-'disulphonic acid (SITS) and 4,4'diisothiocyanostilbene-2,2-'disulphonic acid (DIDS), had no effect upon SEF production. 4. Ouabain, an inhibitor of Na+/K+ ATPase, decreased SEF production substantially at all concentrations added to the SEF (10-3 to 10-6 M). Three sulphonamide inhibitors of carbonic anhydrase, acetazolamide, ethoxzolamide and benzolamide, decreased SEF production when added to the SEF at concentrations of 10-3 to 10-6 M. Benzolamide was by far the most potent. Neither ouabain nor the sulphonamides altered SEF production when added to the albumen culture medium. 5. Using a cobalt precipitation method, carbonic anhydrase activity was localised to the endodermal cells of the area vasculosa. The carbonic anhydrase activity was primarily associated with the lateral plasma membranes, which together with the potent inhibitory effect of benzolamide, suggests the carbonic anhydrase of these cells is the membrane-associated form, CA IV. 6. The changes in SEF composition produced by inhibitors were consistent with the production of SEF by local osmotic gradients. 7. It is concluded that a Na+/K+ ATPase is located on the basolateral membranes of the endodermal cells of the area vasculosa , and that a sodium ion/hydrogen ion exchanger is located on their apical surfaces. Protons for this exchanger would be provided by the hydration of CO2 catalysed by the membrane-associated carbonic anhydrase. Furthermore, it is proposed that the prime function of the endodermal cells of the area vasculosa is the production of SEF

An Envy-Free Cake Division Algorithm

mathematics

Two Stage Auctions I: Private-Value Strategies

game theory ; economic equilibrium ; information

Fair Division by Point Allocation

economic theory

On the harmonic measure of stable processes

Using three hypergeometric identities, we evaluate the harmonic measure of a finite interval and of its complementary for a strictly stable real L{\'e}vy process. This gives a simple and unified proof of several results in the literature, old and recent. We also provide a full description of the corresponding Green functions. As a by-product, we compute the hitting probabilities of points and describe the non-negative harmonic functions for the stable process killed outside a finite interval

Replacing sodium bicarbonate with half amount of calcareous marine algae in the diet of beef cattle

This study evaluated the effects of feeding calcareous marine algae or sodium bicarbonate as rumen buffer on the performance, behaviour, in vitro diet digestibility, and meat quality of beef cattle. A total of 180 Charolaise bullocks (536-38 kg; 14-1 months of age) were divided into two homogeneous groups and fed a diet with a mineral mix containing 40% sodium bicarbonate or 20% calcareous marine algae (CMA) for the entire fattening period (130 days). Of the in vivo and in vitro parameters evaluated, CMA supplementation improved average daily gain and feed conversion ratio and reduced the prevalence of bloat and lameness. Bullocks fed CMA tended to exhibit a calmer behaviour while in the pen. Supplementation with CMA improved rumen pH and in vitro digestion. Meat from bullocks fed CMA showed a lower pH and higher lightness and tenderness. The results suggest that CMA is more effective than sodium bicarbonate in buffering beef cattle, with a positive impact on growth performance, feed efficiency, health, and meat quality

An Internet-Based Course And The Application Of Employment-Based Methods In Civil Engineering Projects

The paper addresses the question of how educational activities in civil engineering in the Netherlands can contribute to the application of employment-based programs in developing countries. National policy makers and international donor representatives acknowledge the various advantages of employment-based programs. However, for a number of reasons the implementation of such programs generally forms a severe bottleneck. Because of the limited number of implemented programs the employment-based methods have not been sufficiently tested and improved, which in turn inhibits reaching the full potential of the employmentbased policies. The University of Twente (UT) has developed a modest program to assist interested governmental and private organisations to enhance the scope and quality of implementation of projects. Based on the existing body of knowledge - to which in particular ILO, WORK and IHE have contributed - a course has been established that can be followed via the Internet. This course offers the basic principles of employment-based civil engineering as well as a framework to develop and implement project proposals. Each of the three modules consists of course material (texts, pictures and films) and an individual assignment that the student submits to the lecturer. Next, the University's internship and traineeship programs provide interested candidates an opportunity to render practical assistance at the spot while at the same time collecting and processing data. After their preparation at the UT the students normally spend 3 to 4 months abroad, frequently in outlying areas. The preparation and execution are carried out under supervision of University staff, while the University also provides financial support by paying for the international travel. Besides their direct contribution to development activities, the students' experiences and reports form the input for improvements in implementation and policy making. So far over 20 students have executed such assignments, mainly in South Africa. The oral presentation of the paper includes a demonstration of the Internet-based course and a discussion with participants on concrete project ideas