Star formation in infrared bright and infrared faint starburst interacting galaxies

Short wavelength IUE spectra of Arp 248b and UGC 8315N are combined with optical spectra and interpreted using a combination of spectrum synthesis and spectral diagnostics to place constraints on the massive star populations of the central regions of these galaxies and to deduce information about the star formation histories in the last 10(exp 8) years. The authors find that both galaxies have substantial fractions of their optical light coming from massive stars and that Arp 248b may be dominated in the UV by WR stars. The UV spectra are dominated by radiation from evolved massive stars and the authors place and age on the burst in Arp 248b of a few tens of millions of years

Protein-based molecular contrast optical coherence tomography with phytochrome as the contrast agent

We report the use of phytochrome A (phyA), a plant protein that can reversibly switch between two states with different absorption maxima (at 660 and 730 nm), as a contrast agent for molecular contrast optical coherence tomography (MCOCT). Our MCOCT scheme builds up a difference image revealing the distribution of phyA within a target sample from pairs of consecutive OCT A-scans acquired at a probe wavelength of 750 nm, both with and without additional illumination of the target sample with 660-nm light. We demonstrate molecular imaging with this new MCOCT modality in a target sample containing a mixture of 0.2% Intralipid and 83 µM of phyA

The University of Minnesota Supplemental Fertilizer Nitrogen Worksheet

The University of Minnesota Supplemental Fertilizer N Worksheet was developed as a simple, quick, reliable, and inexpensive alternative decision aid tool to assess potential fertilizer N losses. The worksheet is a series of three questions with multiple-choice answers. Depending on the answers, numbers are assigned for each question that are summed, and then the recommendation is made for supplemental N applications. It has been used with success for 10 years in Minnesota as a decision aid as well as an educational tool regarding fertilizer N management strategies

Corn Response to Nitrogen Management under Fully-Irrigated vs. Water-Stressed Conditions

Characterizing corn (Zea mays L.) grain yield (GY) response to N is critical for maximizing profits, increasing N use efficiency and minimizing environmental impacts. Although a large database of GY response to N exists for highly productive soils, few data exist for less productive soils. While changes in precipitation are expected in the future, few studies have compared GY response to varying N management practices under conditions of varying water availability. We measured GY and basal stalk nitrate nitrogen (BSN) at harvest using split-applied urea at eight N rates under fully-irrigated (FI) and water-stressed (WS) conditions in a loamy sand over 2 yr (2009 and 2010). We also measured GY and BSN using single, pre-plant applications of urea, polymer-coated urea (PCU) and urea amended with urease and nitrification inhibitors (IU) at one or two N rates. The results showed that economic optimum nitrogen rate (EONR) and agronomic optimum nitrogen rate (AONR) did not vary by water management, in spite of significant increases in GY (up to 48%) under FI compared to WS. Modification of N fertilizer timing or N source was effective for increasing GY (by 18–41%) with FI, but did not affect GY under WS conditions. Averaged across years, BSN was greater with WS compared to FI at most N rates; however, BSN corresponding to AONR was within the optimal range for both water regimes. These findings may have important implications in areas where changes in irrigation practices or water availability are expected under future climate conditions

Protein-based molecular contrast optical coherence tomography

We describe a novel technique for contrast enhancement in optical coherence tomography (OCT) which uses optically switchable protein based chromophores. Photosensitive proteins, such as bacteriorhodopsin and phytochrome, are promising OCT molecular contrast agents by reason of their remarkably low transition activation intensities compatible with in vivo imaging, and their potential for use as genetically expressible markers for molecular imaging. This study details the use of a novel optical switch suppression scheme which uses the absorption change between the two state groups of phytochrome to extract concentration and distribution information of the contrast agent within a target sample

Rounding and uncertainties in parameters determined from fits to experimental data, or a failure to round data-analysis fit parameters properly may make them useless

Almost no physically interesting physico/chemical parameter is determined directly from a measurement. Rather, they are determined by performing a least-squares fit of some model to a set of data. Unfortunately, there seems to be no commonly accepted set of `best practices' for determining how to round off such fitted parameter values to a minimum number of significant digits while ensuring that they retain the ability to reproduce the experimental data within their uncertainties. This sometimes results in lists of fitted parameters with no quoted uncertainties that have 2--3 times as many significant digits as the data being fitted, or to the results of an analysis being defined by parameters that are (unnecessarily?) quoted to more digits than normal computer double precision, which makes those results difficult or impossible to apply. Alternatively, it may also lead to fitted parameters being `over-rounded' so that the model no longer accurately represents the experimental data. This presentation describes a `best practice' to address these problems, offers a general-purpose least-squares fitting program that applies it, and provides an illustrative application of this approach in a study of the A\,^1\Sigma_u^+ - X\,^1\Sigma_g^+ system of Mg$_2$.Ope

Updated perspectives on educational diagnosticians’ understanding of reading assessments

Chappell, Stephens, Kinnison, and Pettigrew (2009) conducted a study investigating educational diagnosticians knowledge of early reading development. Our study replicated the work of Chappell et al. through a mixed methods design that investigated educational diagnosticians’ perceptions and knowledge of early reading development. Additionally, our study sought to gain a better understanding of how educational diagnosticians selected assessment instruments. Our findings suggested that educational diagnosticians may lack understanding of the early developmental processes of reading and that there may be limited use of diagnostic assessment instruments when evaluating students who are struggling to read

QED for a Fibrillar Medium of Two-Level Atoms

We consider a fibrillar medium with a continuous distribution of two-level atoms coupled to quantized electromagnetic fields. Perturbation theory is developed based on the current algebra satisfied by the atomic operators. The one-loop corrections to the dispersion relation for the polaritons and the dielectric constant are computed. Renormalization group equations are derived which demonstrate a screening of the two-level splitting at higher energies. Our results are compared with known results in the slowly varying envelope and rotating wave approximations. We also discuss the quantum sine-Gordon theory as an approximate theory.Comment: 32 pages, 4 figures, uses harvmac and epsf. In this revised version, infra-red divergences are more properly handle