Spin Observables in Antilambda-Lambda Production from Antiproton-Proton Annihilation with a Transverse Inital State Polarization

The formalism describing the scattering of two spin-1/2 objects is reviewed for the case of antilambda-lambda production from antiproton-proton annihilation. It is shown that an experiment utilizing a transverse target polarization can, in principle, completely determine the spin structure of the reaction. Additional measurements, even those using both beam and target polarizations, would not be sensitive to any additional spin dynamics. Thus, the transverse target polarization allows access to the complete set of spin observables, not just the subset upon which the literature has previously focused. This discussion is especially relevant in light of the data collected by PS185/3 at LEAR.Comment: 7 pages, no figure

A multifrequency angular power spectrum analysis of the Leiden polarization surveys

The Galactic synchrotron emission is expected to be the most relevant source of astrophysical contamination in cosmic microwave background polarization measurements, at least at frequencies 30'. We present a multifrequency analysis of the Leiden surveys, linear polarization surveys covering essentially the Northern Celestial Hemisphere at five frequencies between 408 MHz and 1411 MHz. By implementing specific interpolation methods to deal with these irregularly sampled data, we produced maps of the polarized diffuse Galactic radio emission with pixel size of 0.92 deg. We derived the angular power spectrum (APS) (PI, E, and B modes) of the synchrotron dominated radio emission as function of the multipole, l. We considered the whole covered region and some patches at different Galactic latitudes. By fitting the APS in terms of power laws (C_l = k l^a), we found spectral indices that steepen with increasing frequency: from a = -(1-1.5) at 408 MHz to a = -(2-3) at 1411 MHz for 10 < l < 100 and from a = -0.7 to a = -1.5 for lower multipoles (the exact values depending on the considered sky region and polarization mode). The bulk of this steepening can be interpreted in terms of Faraday depolarization effects. We then considered the APS at various fixed multipoles and its frequency dependence. Using the APSs of the Leiden surveys at 820 MHz and 1411 MHz, we determined possible ranges for the rotation measure, RM, in the simple case of an interstellar medium slab model. Taking also into account the polarization degree at 1.4 GHz, we could break the degeneracy between the identified RM intervals. The most reasonable of them turned out to be RM = 9-17 rad/m^2.Comment: 18 pages, 14 figures. Astronomy and Astrophysics, in pres

Therapeutic efficacy of sulfadoxine-pyrimethamine for plasmodium falciparum malaria

Objectives. To assess the therapeutic efficacy of sulfadoxinepyrimethamine (SP) after 5 years of use as first-line treatment of uncomplicated Plasmodium falciparum malaria, and thus guide the selection of artemisinin-based combination therapy in Mpumalanga, South Africa. Design. An open-label, in vivo therapeutic efficacy study of patients with uncomplicated P. falciparum malaria treated with a single oral dose of SP, with response to treatment monitored clinically and parasitologically on days 1, 2, 3, 7, 14, 21, 28 and 42. Setting. Mangweni and Naas public health care clinics, Tonga district in rural Mpumalanga. Subjects, outcome measures and results. Of 152 patients recruited sequentially, 149 (98%) were successfully followed up for 42 days. One hundred and thirty-four patients (90%) demonstrated adequate clinical and parasitological response. Of the 15 patients (10%) who failed treatment, 2 (1.3%) had an early treatment failure, and polymerase chain reaction confirmed recrudescent infection in all 13 patients (8.7%) who had late parasitological (N = 11) or clinical (N = 2) failure. Gametocyte carriage was prevalent following SP treatment (84/152) and this has increased significantly since implementation in 1998 (relative risk 2.77 (confidence interval 1.65 - 4.66); p = 0.00004). Conclusion. Asexual P. falciparum parasites in Mpumalanga remain sensitive to SP, with no significant difference between the baseline cure rate (94.5%) at introduction in 1998, and the present 90% cure rate (p = 0.14). However, since gametocyte carriage has increased significantly we recommend that SP be combined with artesunate in Mpumalanga to reduce gametocyte carriage and thus decrease malaria transmission and potentially delay antimalarial resistance. S Afr Med J 2005; 95: 346-349

Merging of Low-Mass Systems and the Origin of the Fundamental Plane

We present a new set of dissipationless N-body simulations to examine the feasibility of creating bright ellipticals (following the Kormendy relation) by hierarchically merging present-day early-type dwarf galaxies, and to study how the encounter parameters affect the location of the end-product in the $- R_{e}$ plane. We investigate the merging of one-component galaxies of both equal and different masses, the merging of two-component galaxy models to explore the effect of dark halos on the final galaxy characteristics, and the merging of ultracompact dwarf galaxies. We find that the increase of $$ with $R_e$ is attributable to an increase in the initial orbital energy. The merger remnants shift down in the $- R_{e}$ plane and fail to reach the KR. Thus, the KR is not reproducable by mergers of dwarf early-type systems, rendering untenable the theory that present-day dwarfs are responsible for even a small fraction of the present-day ellipticals, unless a considerable amount of dissipation is invoked. However, we do find that present-day dwarfs can be formed by the merger of ultra-compact dwarfs.Comment: 10 pages, 8 figures. Accepted for publication in MNRA

Manners and method in classical criticism of the early eighteenth century

This article explores a neglected period in the history of classical scholarship: the first decades of the eighteenth century. It focuses on the tension between an evolving idea of method, and the tradition of personal polemic which had been an important part of the culture of scholarship since the Renaissance. There are two case studies: the conflict between Jean Le Clerc and Pieter Burman, and the controversy that followed Richard Bentley's edition of Horace's Odes. Both demonstrate the need to revise current paradigms for writing the history of scholarship, and invite us to reconsider the role of methodology in producing of scholarly authority

Terrestrial exposure of a fresh Martian meteorite causes rapid changes in hydrogen isotopes and water concentrations

Determining the hydrogen isotopic compositions and H2O contents of meteorites and their components is important for addressing key cosmochemical questions about the abundance and source(s) of water in planetary bodies. However, deconvolving the effects of terrestrial contamination from the indigenous hydrogen isotopic compositions of these extraterrestrial materials is not trivial, because chondrites and some achondrites show only small deviations from terrestrial values such that even minor contamination can mask the indigenous values. Here we assess the effects of terrestrial weathering and contamination on the hydrogen isotope ratios and H2O contents of meteoritic minerals through monitored terrestrial weathering of Tissint, a recent Martian fall. Our findings reveal the rapidity with which this weathering affects nominally anhydrous phases in extraterrestrial materials, which illustrates the necessity of sampling the interiors of even relatively fresh meteorite falls and underlines the importance of sample return missions

Constraints on spin observables in antiproton-proton to antiLambda-Lambda

It is recalled that spin-observables in the strangeness-exchange reaction $\bar{p}{p} \to \bar{\Lambda}{\Lambda}$ are not independent but are related to each other by simple algebraic relations. This provides constraints on the existing data on polarization and spin-correlation coefficients, and also on the forthcoming data obtained using a polarized proton target.Comment: RevTex, 9 page

Development of mathematical pathways for VET students to articulate to related higher education courses: a focus on engineering

Australia needs more qualified professionals in the Science, Technology, Engineering, and Mathematics (STEM) areas. The national focus on widening participation in higher education (HE) includes strengthening pathways from vocational education and training (VET). VET students often lack the mathematics skills necessary to articulate successfully to their chosen university degrees. Current approaches such as bridging and foundation mathematics programs are not tailored or sufficiently contextualised for VET articulants. This project is developing a mathematics pathway designed to improve the readiness of VET engineering diploma graduates for higher education study in engineering degree programs. Arrangements are flexible so that students can complete these pathways either as part of their engineering diploma as a VET student or as part of preparatory study at the diploma level at university. Many VET students are granted credit when entering a HE course in engineering and can transfer directly to second year units which may assume a level of mathematical knowledge by the university. However, in the VET Diploma of Engineering Technical (MEM50212), there is only one core unit in mathematics (MEM30012A) equivalent to year 9 level and there are two mathematics electives, MEM23004A and MEM23007A, which are part of the advanced diploma and often not taught by many TAFE providers due to student demand and staff capabilities. The lack of required mathematics often leaves the student with a large gap in the required knowledge for success in HE. The project has been underway for over a year and significant progress has been made in developing the pathway for engineering. To date, the mathematical knowledge outcomes from the VET courses have been mapped to the requirements of the HE courses at the University of Tasmania, Flinders University and James Cook University. Gaps in mathematical knowledge have been identified. A formal articulation agreement has been established through TasTAFE and the University of Tasmania where current VET students will be able to enroll in the university foundation mathematics units and receive credit towards their VET diploma in engineering. In addition to the foundation units, the students need to do an online component. This consists of a few compulsory topics which are not covered in the foundation units with supporting examples, practice problems, practical application and self-assessed quizzes for each mathematics topic covered in the foundation units, contextualised to engineering. VET students are applied learners and therefore often struggle with the transition to HE. The online component of the pathway is designed to support the student by providing the context to the mathematics they are learning. Another advantage of the pathway is that it exposes the VET students to HE units and the university environment while satisfying the university mathematics entry requirements

The mass assembly of galaxy groups and the evolution of the magnitude gap

We investigate the assembly of groups and clusters of galaxies using the Millennium dark matter simulation and the associated gas simulations and semi-analytic catalogues of galaxies. In particular, in order to find an observable quantity that could be used to identify early-formed groups, we study the development of the difference in magnitude between their brightest galaxies to assess the use of magnitude gaps as possible indicators. We select galaxy groups and clusters at redshift z=1 with dark matter halo mass M(R200) > 1E13/h Msun, and trace their properties until the present time (z=0). We consider only the systems with X-ray luminosity L_X> 0.25E42/h^2 erg/s at z=0. While it is true that a large magnitude gap between the two brightest galaxies of a particular group often indicates that a large fraction of its mass was assembled at an early epoch, it is not a necessary condition. More than 90% of fossil groups defined on the basis of their magnitude gaps (at any epoch between 0<z<1) cease to be fossils within 4 Gyr, mostly because other massive galaxies are assembled within their cores, even though most of the mass in their haloes might have been assembled at early times. We show that, compared to the conventional definition of fossil galaxy groups based on the magnitude gap Delta m(12)> 2 (in the R-band, within 0.5R200 of the centre of the group), an alternative criterion Delta m(14)>2.5 (within the same radius) finds 50% more early-formed systems, and those that on average retain their fossil phase longer. However, the conventional criterion performs marginally better at finding early-formed groups at the high-mass end of groups. Nevertheless, both criteria fail to identify a majority of the early-formed systems.Comment: 16 pages, 11 figures, 2 tables. Accepted for publication in MNRA