Non-Abelian Braiding of Lattice Bosons

We report on a numerical experiment in which we use time-dependent potentials to braid non-abelian quasiparticles. We consider lattice bosons in a uniform magnetic field within the fractional quantum Hall regime, where $\nu$, the ratio of particles to flux quanta, is near 1/2, 1 or 3/2. We introduce time-dependent potentials which move quasiparticle excitations around one another, explicitly simulating a braiding operation which could implement part of a gate in a quantum computation. We find that different braids do not commute for $\nu$ near $1$ and $3/2$, with Berry matrices respectively consistent with Ising and Fibonacci anyons. Near $\nu=1/2$, the braids commute.Comment: 5 pages, 1 figur

Assessing the Awareness of Lead Hazards in the Greater Burlington Area

Introduction. Lead is a heavy metal found in and around homes built before 1978, comprising more than 80% of the housing stock in Chittenden County, Vermont. Lead exposure during infancy and childhood can have deleterious effects on development. Our study assessed baseline community understanding of potential household lead hazards in Chittenden County, Vermont. Methods.. 123 paper, 10-question surveys were randomly administered to Chittenden County, VT residents to assess recognition of lead toxicology symptoms and awareness of lead safety programs. Scores were treated as continuous variables, demographically grouped, and analyzed using non-parametric statistical analysis (Mann-Whitney & Kruskal-Wallis). Individual questions were treated as dichotomous variables, demographically grouped and analyzed using chi-squared testing. Results.. 48% of survey participants understood the interaction between ADHD and lead or knew the importance of window maintenance. 54.5% were aware of the Burlington Lead Program\u27s assistance program. Participants earning less than $60,000 and those with less than a graduate degree scored statistically lower (p Conclusion.. Lesser-known lead poisoning symptoms and home interventions that decrease lead exposure should be emphasized to the community. High-risk groups requiring targeted education include those who rent, have lower income and education levels. Primary care providers could serve a larger role in educating patients. Additional efforts should be made to publicize services offered by the Burlington Lead Program.https://scholarworks.uvm.edu/comphp_gallery/1241/thumbnail.jp

A Predicted Correlation Between Age Gradient and Star Formation History in FIRE Dwarf Galaxies

We explore the radial variation of star formation histories in dwarf galaxies simulated with Feedback In Realistic Environments (FIRE) physics. The sample contains 9 low-mass field dwarfs with M_ star = 10^5 - 10^7 M_sun from previous FIRE results, and a new suite of 17 higher mass field dwarfs with M_star = 10^7 - 10^9 M_sun introduced here. We find that age gradients are common in our dwarfs, with older stars dominant at large radii. The strength of the gradient correlates with overall galaxy age such that earlier star formation produces a more pronounced gradient. The relation between formation time and strength of the gradient is driven by both mergers and star-formation feedback. Mergers can both steepen and flatten the age gradient depending on the timing of the merger and star formation history of the merging galaxy. In galaxies without significant mergers, early feedback pushes stars to the outskirts at early times. Interestingly, among galaxies without mergers, those with large dark matter cores have flatter age gradients because these galaxies have more late-time feedback. If real galaxies have age gradients as we predict, stellar population studies that rely on sampling a limited fraction of a galaxy can give a biased view of its global star formation history. We show that central fields can be biased young by a few Gyrs while outer fields are biased old. Fields positioned near the 2D half-light radius will provide the least biased measure of a dwarf galaxy's global star formation history.Comment: 13 pages, 8 figures. Submitted to MNRAS, comments welcom

On the Conditions for Neutron-Rich Gamma-Ray Burst Outflows

We calculate the structure and neutron content of neutrino-heated MHD winds driven from the surface of newly-formed magnetars (``proto-magnetars'') and from the midplane of hyper-accreting disks, two of the possible central engines for gamma-ray bursts (GRBs) and hyper-energetic supernovae (SNe). Both the surface of proto-magnetars and the midplane of neutrino-cooled accretion flows (NDAFs) are electron degenerate and neutron-rich (neutron-to-proton ratio n/p >> 1). If this substantial free neutron excess is preserved to large radii in ultra-relativistic outflows, several important observational consequences may result. Weak interaction processes, however, can drive n/p to ~1 in the nondegenerate regions that obtain just above the surfaces of NDAFs and proto-magnetars. Our calculations show that mildly relativistic neutron-rich outflows from NDAFs are possible in the presence of a strong poloidal magnetic field. However, we find that neutron-rich winds possess a minimum mass-loss rate that likely precludes simultaneously neutron-rich and ultra-relativistic (Lorentz factor > 100) NDAF winds accompanying a substantial accretion power. In contrast, proto-magnetars are capable of producing neutron-rich long-duration GRB outflows ~10-30 seconds following core bounce for sub-millisecond rotation periods; such outflows would, however, accompany only extremely energetic events, in which the GRB + SN energy budget exceeds ~ 4e52 ergs. Neutron-rich highly relativistic outflows may also be produced during some short-duration GRBs by geometrically thick accretion disks formed from compact object mergers. The implications for r-process nucleosynthesis, optical transients due to non-relativistic neutron-rich winds, and Nickel production in proto-magnetar and NDAF winds are also briefly discussed.Comment: 24 pages, 7 figures, submitted to Ap

Problems for MOND in Clusters and the Ly-alpha Forest

The observed dynamics of gas and stars on galactic and larger scales cannot be accounted for by self-gravity, indicating that there are large quantities of unseen matter, or that gravity is non-Newtonian in these regimes. Milgrom's MOdified Newtonian Dynamics (MOND) postulates that Newton's laws are modified at very low acceleration, and can account for the rotation curves of galaxies and some other astrophysical observations, without dark matter. Here we apply MOND to two independent physical systems: Ly-alpha absorbers and galaxy clusters. While physically distinct, both are simple hydrodynamical systems with characteristic accelerations in the MOND regime. We find that Ly-alpha absorbers are somewhat smaller than in Newtonian gravity with dark matter, but the result depends crucially on the (unknown) background acceleration field in which they are embedded. In clusters MOND appears to explain the observed (baryonic) mass-temperature relation. However, given observed gas density and enclosed mass profiles and the assumption of hydrostatic equilibrium, MOND predicts radial temperature profiles which disagree badly with observations. We show this explicitly for the Virgo, Abell 2199 and Coma clusters, but the results are general, and seem very difficult to avoid. If this discrepancy is to be resolved by positing additional (presumably baryonic) dark matter, then this dark matter must have ~1-3 times the cluster gas mass within 1 Mpc. This result strongly disfavors MOND as an alternative to dark matter (Abridged).Comment: Revised version. Important caveat in Ly-alpha calculation discussed; conclusions weakened. Coma cluster and calculation of dark matter mass required by MOND added; cluster conclusions strengthened. 11 EmulateApJ pages with 3 embedded figures. Accepted by Ap

Dam design for pastoral stock water supplies

These notes provide information on many components of water harvesting storage systems designed for use in semi-arid areas. The notion of a water harvesting and storage system is deliberately emphasised. No single design component can be considered in isolation if the goal of a drought-proof water supply is to be achieved. A drought-proof surface water supply is achieved by integrating the many design components of a water harvesting/storage system into a practical plan.https://researchlibrary.agric.wa.gov.au/bulletins/1078/thumbnail.jp

Regulation of progesterone receptor signaling by BRCA1 in mammary cancer

Inherited mutations of the BRCA1 gene (chromosome 17q21), a tumor suppressor, lead to an increased risk of breast cancer, ovarian cancer, and several other hormone-responsive tumor types. Over the last ten years, BRCA1 has been found to play major roles in DNA damage signaling, repair, and cell cycle checkpoints. In addition, unfolding evidence suggests that BRCA1 functions as a co-regulator for steroid hormone receptors and modulates steroid hormone action. In this paper, we will briefly review this evidence and present a model to address the role of the progesterone and estrogen receptors in BRCA1 mutant mammary carcinogenesis. Finally, we will consider some of the clinical implications of this model

Chiral Hierarchies, Compositeness and the Renormalization Group

A wide class of models involve the fine--tuning of significant hierarchies between a strong--coupling ``compositeness'' scale, and a low energy dynamical symmetry breaking scale. We examine the issue of whether such hierarchies are generally endangered by Coleman--Weinberg instabilities. A careful study using perturbative two--loop renormalization group methods finds that consistent large hierarchies are not generally disallowed.Comment: 22 pp + 5 figs (uuencoded and submitted separately), SSCL-Preprint-490; FERMI-PUB-93/035-

A Candidate Substellar Companion to HR 7329

We present the discovery of a candidate substellar companion from a survey of nearby, young stars with the NICMOS coronagraph on the Hubble Space Telescope. The H ~ 12 mag object was discovered approximately 4" from the young A0V star HR 7329. Using follow-up spectroscopy from STIS, we derive a spectral type between M7V and M8V with an effective temperature of ~ 2600 K. We estimate that the probability of a chance alignment with a foreground dwarf star of this nature is ~ 10^(-8) and therefore suggest the object (HR 7329B) is physically associated with HR 7329 with a projected separation of 200 AU. Current brown dwarf cooling models indicate a mass of less than 50 Jupiter masses for HR 7329B based on age estimates of < 30 Myr for HR7329A.Comment: 8 pages LATEX, 5 ps figures, accepted for Ap

Choline transporter-like protein 4 (CTL4) links to non-neuronal acetylcholine synthesis.

Synthesis of acetylcholine (ACh) by non-neuronal cells is now well established and plays diverse physiologic roles. In neurons, the Na(+) -dependent, high affinity choline transporter (CHT1) is absolutely required for ACh synthesis. In contrast, some non-neuronal cells synthesize ACh in the absence of CHT1 indicating a fundamental difference in ACh synthesis compared to neurons. The aim of this study was to identify choline transporters, other than CHT1, that play a role in non-neuronal ACh synthesis. ACh synthesis was studied in lung and colon cancer cell lines focusing on the choline transporter-like proteins, a five gene family choline-transporter like protein (CTL)1-5. Supporting a role for CTLs in choline transport in lung cancer cells, choline transport was Na(+) -independent and CTL1-5 were expressed in all cells examined. CTL1, 2, and 5 were expressed at highest levels and knockdown of CTL1, 2, and 5 decreased choline transport in H82 lung cancer cells. Knockdowns of CTL1, 2, 3, and 5 had no effect on ACh synthesis in H82 cells. In contrast, knockdown of CTL4 significantly decreased ACh secretion by both lung and colon cancer cells. Conversely, increasing expression of CTL4 increased ACh secretion. These results indicate that CTL4 mediates ACh synthesis in non-neuronal cell lines and presents a mechanism to target non-neuronal ACh synthesis without affecting neuronal ACh synthesis