Covers of acts over monoids II

In 1981 Edgar Enochs conjectured that every module has a flat cover and finally proved this in 2001. Since then a great deal of effort has been spent on studying different types of covers, for example injective and torsion free covers. In 2008, Mahmoudi and Renshaw initiated the study of flat covers of acts over monoids but their definition of cover was slightly different from that of Enochs. Recently, Bailey and Renshaw produced some preliminary results on the `other' type of cover and it is this work that is extended in this paper. We consider free, divisible, torsion free and injective covers and demonstrate that in some cases the results are quite different from the module case

ALICE: The Ultraviolet Imaging Spectrograph aboard the New Horizons Pluto-Kuiper Belt Mission

The New Horizons ALICE instrument is a lightweight (4.4 kg), low-power (4.4 Watt) imaging spectrograph aboard the New Horizons mission to Pluto/Charon and the Kuiper Belt. Its primary job is to determine the relative abundances of various species in Pluto's atmosphere. ALICE will also be used to search for an atmosphere around Pluto's moon, Charon, as well as the Kuiper Belt Objects (KBOs) that New Horizons hopes to fly by after Pluto-Charon, and it will make UV surface reflectivity measurements of all of these bodies as well. The instrument incorporates an off-axis telescope feeding a Rowland-circle spectrograph with a 520-1870 angstroms spectral passband, a spectral point spread function of 3-6 angstroms FWHM, and an instantaneous spatial field-of-view that is 6 degrees long. Different input apertures that feed the telescope allow for both airglow and solar occultation observations during the mission. The focal plane detector is an imaging microchannel plate (MCP) double delay-line detector with dual solar-blind opaque photocathodes (KBr and CsI) and a focal surface that matches the instrument's 15-cm diameter Rowland-circle. In what follows, we describe the instrument in greater detail, including descriptions of its ground calibration and initial in flight performance.Comment: 24 pages, 29 figures, 2 tables; To appear in a special volume of Space Science Reviews on the New Horizons missio

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

The effect of MgO on the liquidus temperatures of fayalite slags

The effects of minor MgO additions on the liquidus temperatures of fayalite slag have been investigated experimentally in equilibrium with metallic iron. The synthetic slags were equilibrated, quenched, and subsequently examined by using optical microscopy and electron probe X-ray microanalysis. Liquidus isotherms in the fayalite primary field and boundary lines were determined in the multicomponent systems MgO-"FeO"-CaO-SiO and AlO-MgO-"FeO"-CaO-SiO in equilibrium with metallic iron. The experimental results show that the magnesia addition expands the fayalite primary phase field in size and increases the liquidus temperatures in the fayalite primary phase field. It has been found that the effects of alumina and magnesia additions on the liquidus temperatures in the fayalite primary phase field are independent of each other