Silicon consumption and population density changes of dominant planktonic diatoms in Lake Constance

(1) Interactions between silicon concentration and diatom growth have been studied in Lake Constance with data on number and volume of cells per unit volume of water and concentration of dissolved reactive silicon. (2) Concentration of dissolved reactive silicon was found to decrease markedly during the spring and summer growth period of diatoms in 1979 and 1980. (3) Amounts of silicon taken up per cell and per unit cell volume have been calculated from the changes in silicon concentration and the increases in population density for several diatom species. The silicon to cell quotient (mg per million cells) varied over a wide range from 0.005 for Stephanodiscus hantzschii to 0.72 for Synedra acus, while that of silicon per unit cell volume (mg mm-3) varied over a narrower range from 0. 10 for Stephanodiscus hantzschii and Fragilaria crotonesis to 0.36 for Synedra acus. (4) A four-compartment model, that allows estimates of the rates of growth and of loss of diatom populations to be calculated, is outlined. (5) Summer succession from Asterionellaformosa to either Fragilaria crotonensis (in 1979) or Stephanodiscus binderanus (in 1980) is explained by interspecific differences in the effects of silicon concentration on growth and death. For Asterionellaformosa, silicon depletion did not stop cell-division but led to the death of most of the population. For Fragilaria crotonensis and Stephanodiscus binderanus cell division stopped but cells did not die and population growth continued after the concentration of dissolved silicon had increased agai

Hadron masses from dynamical, non-perturbatively O(a) improved Wilson fermions

We present results on light hadron masses from simulations of full QCD and report on experiences in running such simulations on a Hitachi SR8000-F1 supercomputer.Comment: Lattice 2000 (Spectrum), 4 pages, 6 eps figure

The Density Profile of Cluster-scale Dark Matter Halos

We measure the average gravitational shear profile of 6 massive clusters (M_vir ~ 10^15 M_sun) at z=0.3 out to a radius ~2h^-1 Mpc. The measurements are fitted to a generalized NFW-like halo model \rho(r) with an arbitrary r -> 0 slope \alpha. The data are well fitted by such a model with a central cusp with \alpha ~ 0.9 - 1.6 (68% confidence interval). For the standard-NFW case \alpha = 1.0, we find a concentration parameter c_vir that is consistent with recent predictions from high-resolution CDM N-body simulations. Our data are also well fitted by an isothermal sphere model with a softened core. For this model, our 1\sigma upper limit for the core radius corresponds to a limit \sigma_star \leq 0.1 cm^2 g^-1 on the elastic collision cross-section in a self-interacting dark matter model.Comment: 4 pages, 3 figures; version accepted for publication by ApJ Letters. Three figures omitted to allow space for new fig. 3 and expanded results and discussion sections, including NSIS model fi

Commentary: Where Is the Economic Analysis of Payment Law?

Modem payment law began precisely a quarter of a millennium ago, when Lord Mansfield decided Miller v. Race. After 250 years, we know little more than Mansfield, even with the analytic power of modern neoclassical microeconomics. Many of the simplest questions have no easy answer: What is a payment? (The U.C.C. has no definition.) What is payment finality, and why is it important? (There is no consensus, especially because payment finality was law long before bankers discovered its connection to systemic risk.) What is the normative rationale of the clearing and settlement rules in the U.C.C.? (Again, no consensus, and not even much commentary.) What is the proper scope of payment law? (Explain why U.C.C. Article 5 is in most payment casebooks, and the law of suretyship is not.) Neoclassical microeconomics has been a general success in business law: a facile framework for difficult legal problems. But it has not worked in payment law, with a few exceptions such as the allocation of risk for fraud and mistake. Is there a reason for this? Read this commentary to find out

Music Teacher Knowledge: An Examination of the Intersections Between Instrumental Music Teaching and Conducting.

The purpose of this study was to examine the complexities of instrumental music teacher knowledge and explore how participants describe the intersections between instrumental music teaching and conducting. The key research question guiding this study was: How do high school instrumental music teachers describe the intersections between instrumental music teaching and conducting? Sub questions include (a) What key experiences do instrumental music teachers describe as being most meaningful to their development as teachers and conductors? (b) Which aspects of practice do instrumental music teachers perceive and describe as being related to the intersection between instrumental music teaching and their development as conductors, and (c) What dilemmas of practice do instrumental music teachers perceive and describe as being related to the intersection between instrumental music teaching and their development as conductors? This study focused on the participants’ (N = 4) perceptions and descriptions of the intersections between instrumental music teaching and conducting. A multiple case study design (Stake, 2006) was used to examine the commonalities and unique aspects across cases. Sources of data included: participant interviews, one participant focus group, one observation of each of the participants conducting and teaching their high school ensembles, and two stimulated recall events with each participant using previously recorded conducting footage. The central finding of this study suggests that the practice of instrumental music teaching demands a specialized form of knowledge that reflects the integration of, rather than the intersection between, both teaching and conducting. This specialized form of knowledge informs the participants’ in-the-moment decision-making, judgments, and communication with students and the ensemble as a whole. The dilemmas of practice related to instrumental music teaching and conducting include the participants’ ability to listen, assess, and respond to sound in the moment, and their ability to apply powerful lessons and experiences from mentor teachers and/or professional role models to their specific teaching context. The findings of this study suggest implications for music teacher education and conducting education, specifically in the areas of devising professional development opportunities that are systematic, multilevel, and multifaceted, and that mirror the integrated nature of teaching and conducting that occurs in practice.PhDMusic: Music EducationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111554/1/sommerb_1.pd