Analysis of trace elements in forages by near infrared reflectance spectroscopy

Use of near infrared reflectance spectroscopy (NIRS) for elemental analysis has been limited to a few elements including Ca, P, K, and Mg. However, other elements are of interest in the agricultural industry. Therefore, NIRS spectra were collected on forage samples consisting of tall fescue (Festuca arundinacea Schreb.), crested wheatgrass (Agropyron cristatum and A. desertorum), and alfalfa (Medicago sativa L.). Elemental concentrations of Ba, Li, Mo, Ni, Pb, V, Al, S, and Si were determined by ICP (Inductively Coupled Argon Plasma) analysis while selenium (Se) was determined by fluorometry. The elemental analyses were regressed against NIRS apparent absorption from 1100 to 2500 nm at 2-nm increments. Coefficients of variation /CV = (standard error of performance / the mean from the chemical procedure) X 1001 ranged from a high of 211% for Li in crested wheatgrass to 11% for S in alfalfa. Determination of Ba, Li, Mo, Ni, Pb, and V exhibited enough inconsistency in CVs among the three forages to preclude their determination with NIRS. Aluminum and S appear to be present in an organic form that NIRS is able to detect (CV = 22 and 15, 21 and 12, and 28 and 11%, for tall fescue, crested wheatgrass, and alfalfa, respectively). Silica exhibited slightly more variation than S or Al, with alfalfa having the highest CV (49%). Selenium was only determined on a tall fescue population with a CV = 27%. Using the statistical values as parameters indicative of NIRS utility, it appears that Al and S are the only elements in this group of minerals that can be determined with NIRS for these forage types

Companions of Stars: From Other Stars to Brown Dwarfs to Planets: The Discovery of the First Methane Brown Dwarf

The discovery of the first methane brown dwarf provides a framework for describing the important advances in both fundamental physics and astrophysics that are due to the study of companions of stars. I present a few highlights of the history of this subject along with details of the discovery of the brown dwarf Gliese 229B. The nature of companions of stars is discussed with an attempt to avoid biases induced by anthropocentric nomenclature. With the newer types of remote reconnaissance of nearby stars and their systems of companions, an exciting and perhaps even more profound set of contributions to science is within reach in the near future. This includes an exploration of the diversity of planets in the universe and perhaps soon the first solid evidence for biological activity outside our Solar System.Comment: 31 pages, 13 figure

Ecological Invasion, Roughened Fronts, and a Competitor's Extreme Advance: Integrating Stochastic Spatial-Growth Models

Both community ecology and conservation biology seek further understanding of factors governing the advance of an invasive species. We model biological invasion as an individual-based, stochastic process on a two-dimensional landscape. An ecologically superior invader and a resident species compete for space preemptively. Our general model includes the basic contact process and a variant of the Eden model as special cases. We employ the concept of a "roughened" front to quantify effects of discreteness and stochasticity on invasion; we emphasize the probability distribution of the front-runner's relative position. That is, we analyze the location of the most advanced invader as the extreme deviation about the front's mean position. We find that a class of models with different assumptions about neighborhood interactions exhibit universal characteristics. That is, key features of the invasion dynamics span a class of models, independently of locally detailed demographic rules. Our results integrate theories of invasive spatial growth and generate novel hypotheses linking habitat or landscape size (length of the invading front) to invasion velocity, and to the relative position of the most advanced invader.Comment: The original publication is available at www.springerlink.com/content/8528v8563r7u2742

Herschel*-ATLAS: correlations between dust and gas in local submm-selected galaxies

We present an analysis of CO molecular gas tracers in a sample of 500 μ m-selected Herschel -ATLAS galaxies at z < 0 . 05 ( cz < 14990 km s − 1 ). Using 22 − 500 μ m photom- etry from WISE , IRAS and Herschel , with H i data from the literature, we investigate correlations between warm and cold dust, and tracers of the gas in different phases. The correlation between global CO(3–2) line fluxes and FIR–submm fl uxes weakens with increasing IR wavelength ( λ & 60 μ m), as a result of colder dust being less strongly associated with dense gas. Conversely, CO(2–1) and H i line fluxes both ap- pear to be better correlated with longer wavelengths, suggesting that cold dust is more strongly associated with diffuse atomic and molecular gas phases, co nsistent with it being at least partially heated by radiation from old stellar populations . The increased scatter at long wavelengths implies that sub-millimetre fluxes are a po orer tracer of SFR. Fluxes at 22 and 60 μ m are also better correlated with diffuse gas tracers than dense CO(3–2), probably due to very-small-grain emission in the diffu se interstellar medium, which is not correlated with SFR. The FIR/CO luminosity ratio a nd the dust mass/CO luminosity ratio both decrease with increasing luminosit y, as a result of either correlations between mass and metallicity (changing CO/H 2 ) or between CO luminosity and excitation [changing CO(3–2)/CO(1–0)].Web of Scienc

Determinants of international students' academic performance: A comparison between Chinese and other international students

With the increasing number of international students travelling to well-developed countries for higher education, there has been a growing interest in exploring the factors that influence their academic performance during their overseas studies. This study aims to give an insight into international students' learning experience by investigating the differences between Chinese and non-Chinese cultural groups and leads to the identification of the key predictors of their academic achievement via multiple regression analysis. The results suggest that the perceived importance of learning success to family, English writing ability, and social communication with their compatriots are significant predictors for all international students. As the predominant group, Chinese students display some distinctive characteristics. A less active learning strategy is observed among Chinese students relative to others, but no evidence has found that this negatively affects their academic achievement. © 2010 Nuffic

Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization