B\"ottcher coordinates

A well-known theorem of B\"ottcher asserts that an analytic germ f:(C,0)->(C,0) which has a superattracting fixed point at 0, more precisely of the form f(z) = az^k + o(z^k) for some a in C^*, is analytically conjugate to z->az^k by an analytic germ phi:(C,0)->(C,0) which is tangent to the identity at 0. In this article, we generalize this result to analytic maps of several complex variables

Hot Stars With Cool Companions

Young intermediate-mass stars have become high-priority targets for direct-imaging planet searches following the recent discoveries of planets orbiting e.g. HR 8799 and Beta Pictoris. Close stellar companions to these stars can affect the formation and orbital evolution of any planets, and so a census of the multiplicity properties of nearby intermediate mass stars is needed. Additionally, the multiplicity can help constrain the important binary star formation physics. We report initial results from a spectroscopic survey of 400 nearby A- and B-type stars. We search for companions by cross-correlating high resolution and high signal-to-noise ratio echelle spectra of the targets stars against model spectra for F- to M-type stars. We have so far found 18 new candidate companions, and have detected the spectral lines of the secondary in 4 known spectroscopic binary systems. We present the distribution of mass-ratios for close companions, and find that it differs from the distribution for wide ($a < 100$ AU) intermediate-mass binaries, which may indicate a different formation mechanism for the two populations.Comment: Submitted as part of the 18th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun Proceedings of Lowell Observatory (9-13 June 2014

Correcting For Telluric Absorption: Methods, Case Studies, And Release Of The TelFit Code

Ground-based astronomical spectra are contaminated by the Earth's atmosphere to varying degrees in all spectral regions. We present a Python code that can accurately fit a model to the telluric absorption spectrum present in astronomical data, with residuals of similar to 3%-5% of the continuum for moderately strong lines. We demonstrate the quality of the correction by fitting the telluric spectrum in a nearly featureless A0V star, HIP 20264, as well as to a series of dwarf M star spectra near the 819 nm sodium doublet. We directly compare the results to an empirical telluric correction of HIP 20264 and find that our model-fitting procedure is at least as good and sometimes more accurate. The telluric correction code, which we make freely available to the astronomical community, can be used as a replacement for telluric standard star observations for many purposes.UT Austin Hutchinson fellowshipUniversity of TexasAstronom

Alternative Treatment Options for Controlling Anthelmintic-Resistant \u3cem\u3eHaemonchus contortus\u3c/em\u3e Populations in South Dakota Sheep Herds

Haemonchus contortus is a common economically important gastrointestinal nematode that obliges the survival and productivity of small ruminants, especially sheep and goats. Anthelmintic resistance is a primary challenge in ruminant health management programs in preventing and controlling the H. contortus populations; therefore, there is a great necessity in finding and developing natural plant products for use as alternatives to commercial anthelmintics for controlling H. contortus in pastured sheep and goats. This dissertation has three major aims conducted in three separate studies: the first in vivo one was to evaluate the extended effect of a springtime, combined-treatment with 3 anthelmintics having different mechanism of action including moxidectin (Cydectin®), albendazole (Valbazen®), and levamisole (all given orally); this project was also coupled with a rotational grazing program on egg shedding in the United States Northern Great Plains flock of ewes whose H. contortus population showed benzimidazole and avermectin resistance. The results of fecal egg counts (FECs) 2 weeks before and after the treatment for 250 ewes showed a 99.99% FEC reduction from 3650 eggs per gram (EPG) to 0.17 EPG. The egg output remained very low until 10 weeks on paddocks. Output peaked on the 16th week at 42.1 EPG. During the following year, mean spring FEC was only 66.1 EPG and only 5.1 for the fall. Unfortunately, by the spring of 2016 egg output had increased to 1116.0 and remained high in 2017. The second study was an in vitro project aimed to measure the anthelmintic activity of Melilotus alba (white sweet clover) on H. contortus. The anthelmintic activity of methanol extracts from different sweet clover plant parts (i.e. leaves, stems, pods) were measured using a larval migration assay involving unsheathed third-stage H. contortus juveniles (J3). Stems and pods showed no anthelmintic activity, while 97.3% migration inhibition was measured in the leaf-extract at 30 mg/ml. An aqueous extract of the leaves (concentration of 670 mg/ml water) inhibited migration by 98% after 24 hrs., and no motility was observed after 48 hrs. Inhibition was higher at an acidic pH (e.g. pH of 3 and 5) than at a neutral pH (e.g. 7.4). Cytotoxicity of the aqueous leaf-extract was measured with unpolarized bovine ileal epithelial cells at 5 differing concentrations of the extract using an absorbance-based AlamarBlue assay. This assay showed that the extracts were vey toxic (100% cytotoxicity) at high concentrations. The goal of the third study was to evaluate M. alba anthelmintic effect on H. contortus under in vivo conditions. The experimental yearling ewes naturally and heavily infected with H. contortus were fed 0.68 kg of fresh-frozen M. alba (white sweet clover) (harvested from local plants in late fall) per day for 2 weeks. FECs were determined daily after the 2 weeks to estimate the post-treatment worm loads. Under these conditions, the results did not show any decrease in egg shedding, no significant effect (p \u3e 0.05), within either experimental groups compared to the controls, but it showed an unexpected significant rise in egg output during the treatment period. The findings of these three studies suggest that the hypobiotic fourth-stage juveniles is the major cause of the rapid massive increase in H. contortus in spring; therefore keeping the animals inside the barns for a full year and applying a combined triple treatment while the animals are still inside the barns might help in the eradication of the arresting J4, then the next step is to run FECs next spring, and if the results showed no evidence of haemonchosis, then the animals could be released to the pasture using a rotational grazing system. Since the M. alba leaf-extracts showed signs of cytotoxicity to the unpolarized cells, this evidence should be investigated deeply using polarized intestinal cell lines and high doses of leaves should be given to experimental animals. If the future testing of white sweat clover extracts revealed no sign of toxicity, drenches of concentrated leafextracts and/or first-year plants containing mostly leaves could be fed to H. contortus infected sheep and goats. Such studies are encouraged to better evaluate the usefulness of feeding M. alba leaves

Numerical calculation of ion runaway distributions

Ions accelerated by electric fields (so-called runaway ions) in plasmas may explain observations in solar flares and fusion experiments, however limitations of previous analytic work have prevented definite conclusions. In this work we describe a numerical solver of the 2D non-relativistic linearized Fokker-Planck equation for ions. It solves the initial value problem in velocity space with a spectral-Eulerian discretization scheme, allowing arbitrary plasma composition and time-varying electric fields and background plasma parameters. The numerical ion distribution function is then used to consider the conditions for runaway ion acceleration in solar flares and tokamak plasmas. Typical time scales and electric fields required for ion acceleration are determined for various plasma compositions, ion species and temperatures, and the potential for excitation of toroidal Alfv\'en eigenmodes during tokamak disruptions is considered.Comment: 25 pages, 8 figure

Medical Care Expenditure Indexes: A Comparison of Indexes using MarketScan and Pharmetrics Data

In recent years, healthcare service utilization has undergone several shifts, having potentially important implications for the cost of medical care.