HFPK 334: An unusual Supernova Remnant in the Small Magellanic Cloud

We present new Australia Telescope Compact Array (ATCA) radio-continuum and XMM-Newton/Chandra X-ray Observatory (CXO) observations of the unusual supernova remnant HFPK 334 in the Small Magellanic Cloud (SMC). The remnant follows a shell type morphology in the radio-continuum and has a size of $\sim$20~pc at the SMC distance. The X-ray morphology is similar, however, we detect a prominent point source close to the center of the SNR exhibiting a spectrum with a best fit powerlaw with a photon index of $\Gamma = 2.7 \pm 0.5$. This central point source is most likely a background object and cannot be directly associated with the remnant. The high temperature, nonequilibrium conditions in the diffuse region suggest that this gas has been recently shocked and point toward a younger SNR with an age of $\lesssim 1800$ years. With an average radio spectral index of $\alpha=-0.59\pm0.09$ we find that an equipartition magnetic field for the remnant is $\sim$90~$\mu$G, a value typical of younger SNRs in low-density environments. Also, we report detection of scattered radio polarisation across the remnant at 20~cm, with a peak fractional polarisation level of 25$\pm$5\%.Comment: 19 pages, 6-figures, submitted to A

Non-random dispersal in the butterfly Maniola jurtina: implications for metapopulation models

The dispersal patterns of animals are important in metapopulation ecology because they affect the dynamics and survival of populations. Theoretical models assume random dispersal but little is known in practice about the dispersal behaviour of individual animals or the strategy by which dispersers locate distant habitat patches. In the present study, we released individual meadow brown butterflies (Maniola jurtina) in a non-habitat and investigated their ability to return to a suitable habitat. The results provided three reasons for supposing that meadow brown butterflies do not seek habitat by means of random flight. First, when released within the range of their normal dispersal distances, the butterflies orientated towards suitable habitat at a higher rate than expected at random. Second, when released at larger distances from their habitat, they used a non-random, systematic, search strategy in which they flew in loops around the release point and returned periodically to it. Third, butterflies returned to a familiar habitat patch rather than a non-familiar one when given a choice. If dispersers actively orientate towards or search systematically for distant habitat, this may be problematic for existing metapopulation models, including models of the evolution of dispersal rates in metapopulations

Neutron-proton analyzing power at 12 MeV and inconsistencies in parametrizations of nucleon-nucleon data

We present the most accurate and complete data set for the analyzing power Ay(theta) in neutron-proton scattering. The experimental data were corrected for the effects of multiple scattering, both in the center detector and in the neutron detectors. The final data at En = 12.0 MeV deviate considerably from the predictions of nucleon-nucleon phase-shift analyses and potential models. The impact of the new data on the value of the charged pion-nucleon coupling constant is discussed in a model study.Comment: Six pages, four figures, one table, to be published in Physics Letters

Update on a Pharmacokinetic-Centric Alternative Tier II Program for MMT—Part I: Program Implementation and Lessons Learned

Concerns have been raised regarding environmental manganese exposure since high exposures have been associated with neurological disorders. The USA Environmental Protection Agency most recent human health risk assessment of inhaled manganese conducted in 1993 identified specific areas of uncertainty regarding manganese pharmacokinetics. This led to the development of a test rule under the USA Clean Air Act that required the generation of pharmacokinetic information on the inorganic manganese combustion products of the organometallic fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT). The Alternative Tier 2 testing program for MMT, described in this paper, has yielded substantial pharmacokinetic data and has enabled the generation of physiologically based pharmacokinetic (PBPK) models for manganese. These models are capable of predicting tissue manganese concentrations across a variety of dose routes, levels, and durations while accounting for factors such as age, gender, and reproductive status, enabling the consideration of tissue dosimetry in future risk assessments

Testing an Intentional Naming Scheme Using Genetic Algorithms

Abstract. Various attempts have been made to use genetic algorithms (GAs) for software testing, a problem that consumes a large amount of time and eort in software development. We demonstrate the use of GAs in automating testing of complex data structures and methods for manipulating them, which to our knowledge has not been successfully displayed before on non-trivial software structures. We evaluate the ef-fectiveness of our GA-based test suite generation technique by applying it to test the design and implementation of the Intentional Naming Sys-tem (INS), a new scheme for resource discovery and service location in a dynamic networked environment. Our analysis using GAs reveals serious problems with both the design of INS and its inventors ' implementation.

Mechanism of Pion Production in alphaalphap Scattering at 1 GeV/nucleon

The one-pion and two-pion production in the p(alpha, alpha prime)X reaction at an energy of E{alpha} = 4.2 GeV has been studied by simultaneous registration of the scattered alpha particles and the secondary pion or proton. The obtained results demonstrate that the inelastic alpha-particle scattering on the proton at the energy of the experiment proceeds either through excitation and decay of Delta resonance in the projectile or through excitation in the target proton of the Roper resonance, which decays mainly on a nucleon and a pion or a nucleon and a sigma meson - system of two pions in the isospin I = 0, S-wave.Comment: 16 pages, 10 figures. Submitted to Proceedings of the XX International Baldin Seminar on High - Energy Physics Problems, Dubna, October 4 - 9, 201

Reversible [4 + 1] Cycloaddition of Arenes by a “Naked” Acyclic Aluminyl Compound

The large steric profile of the N-heterocyclic boryloxy ligand, –OB­(NDippCH)2, and its ability to stabilize the metal-centered HOMO, are exploited in the synthesis of the first example of a “naked” acyclic aluminyl complex, [K­(2.2.2-crypt)]­[Al­{OB­(NDippCH)2}2]. This system, which is formed by substitution at AlI (rather than reduction of AlIII), represents the first O-ligated aluminyl compound and is shown to be capable of hitherto unprecedented reversible single-site [4 + 1] cycloaddition of benzene. This chemistry and the unusual regioselectivity of the related cycloaddition of anthracene are shown to be highly dependent on the availability (or otherwise) of the K+ countercation

A New Measurement of the 1S0 Neutron-Neutron Scattering Length using the Neutron-Proton Scattering Length as a Standard

The present paper reports high-accuracy cross-section data for the 2H(n,nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np obtained from neutron-deuteron (nd) breakup agrees with that from free np scattering, we conclude that our investigation of the nn FSI done simultaneously and under identical conditions gives the correct value for a_nn. Our value for a_nn is in agreement with that obtained in pion-deuteron capture measurements but disagrees with values obtained from earlier nd breakup studies.Comment: 4 pages and 3 figure

Low-energy Pion-nucleon Scattering

This paper contains the results of an analysis of recent low-energy pion-nucleon scattering experiments. Obtained are phase shifts, the pion-nucleon coupling constant and an estimate of the Sigma term.Comment: 30 pages, 11 figures, LaTe