Development report: Automatic System Test and Calibration (ASTAC) equipment

A microcomputer based automatic test system was developed for the daily performance monitoring of wind energy system time domain (WEST) analyzer. The test system consists of a microprocessor based controller and hybrid interface unit which are used for inputing prescribed test signals into all WEST subsystems and for monitoring WEST responses to these signals. Performance is compared to theoretically correct performance levels calculated off line on a large general purpose digital computer. Results are displayed on a cathode ray tube or are available from a line printer. Excessive drift and/or lack of repeatability of the high speed analog sections within WEST is easily detected and the malfunctioning hardware identified using this system

Decomposing color structure into multiplet bases

We illustrate how QCD color structure elegantly can be decomposed into orthogonal multiplet bases corresponding to irreducible representations of SU(Nc) with the aid of Wigner 3j and 6j coefficients. We also show how to calculate the relevant 3j and 6j coefficients using multiplet bases and birdtrack techniques and argue that only a relatively small number of Wigner 3j and 6j coefficients are required. For up to six gluons plus quark-antiquark pairs we explicitly calculate all 6j coefficients required for up to NLO calculations.Comment: Version published in JHE

Vimentin in mammary gland morphogenesis and contractility during lactation

The mammary gland becomes fully differentiated upon pregnancy and lactation preparing it for nourishing the offspring. Mammary basal epithelial cells lining the ducts and alveoli contract to propel the secreted milk to the nipple. These cells express vimentin intermediate filaments, which have been shown to be involved in development and regulation of cell mechanical strength and movement. While vimentin deficiency was shown to reduce basal epithelial cell proportion and delay ductal outgrowth during pubertal mammary gland development, little is known about the role of vimentin in the lactating mammary gland. In this research project the role of vimentin in basal cell contractility and lactogenic differentiation was explored. The comparison of lactating mammary gland phenotype in wild type (WT) and vimentin knock-out (Vim-/-) mice showed no clear differences, but detailed image analysis revealed a large variation in the alveolar size and disorganised morphology in Vim-/- mammary gland. While milk lipid droplets were fewer but larger inside lactating Vim-/- mammary epithelial cells, the analysis of milk spots and litter weights in the pups of WT and Vim-/- dams demonstrated no significant effects on nursing, suggesting that any defects in lactational differentiation are likely compensated with other mechanisms. Furthermore, no consistent changes in the contractile readout, myosin II phosphorylation, upon vimentin silencing or knockout were detected in human and mouse mammary glands, respectively. This might further reflect the adaptive capacity of the organ to sustain the vital function in mammals. Further details of vimentin in mammary gland function might be detected when examining the actively contracting gland

Resilience in ecology and sustainability science

Peer reviewe

Linear instability for incompressible inviscid fluid flows : two classes of perturbations

textOne approach to examining the stability of a fluid flow is to linearize the evolution equation at an equilibrium and determine (if possible) the stability of the resulting linear evolution equation. In this dissertation, the space of perturbations of the equilibrium flow is split into two classes and growth of the linear evolution operator on each class is analyzed. Our classification of perturbations is most naturally described in V.I. Arnold’s geometric view of fluid dynamics. The first class of perturbations we examine are those that preserve the topology of vortex lines and the second class is the factor space corresponding to the first class. In this dissertation we establish lower bounds for the essential spectral radius of the linear evolution operator restricted to each class of perturbations.Mathematic

The Development of a New Anemometer for Measuring High Speed Winds on Mount Washington, New Hampshire

Mount Washington, NH is well known as the Home of the Worlds Worst Weather. Winds on the mountain regularly exceed 100 miles per hour, the record being 231 mph on April 12, 1934. There is a long history of weather observation on the mountain that has included various recording techniques. Until recently, the primary means of recording data has been paper strip charts. This project represents significant improvements to the Observatory\u27s instrumentation system. Measuring windspeed on Mount Washington presents a number of design challenges. Any instruments directly exposed to the weather must be very durable. Fortunately this problem had been solved and allowed attention to be focused on the instrumentation. The challenge then becomes ensuring the accuracy and reliability of measurements taken from the instruments. This involves electrical interfacing concerns and decisions about how best to distribute the computation of the collected data. The part of this work that was the biggest success is the hardware. For the first time, the Observatory has research grade instruments for measuring and recording windspeed, barometric pressure and temperature and a proper error analysis on each instrument

Chemical abundances in cool metal rich disk dwarf stars

The present study of spectra of twelve metal-rich cool dwarf stars, carefully selected in order to cover a range of temperatures (~4400 - 6000 K), is a follow up on Feltzing & Gustafsson (1998, A&AS 129, 237) with the aim to understand the apparent over-ionization and anomalous elemental abundances found by them for the K dwarf stars in their sample. Our method of analysis employs synthetic spectra of the full spectrum both to constrain the continuum level and to derive abundances. It is shown that by using this method and imposing a strict excitation equilibrium (possible to do because of the care in selection of observed Fe I lines) we are able to show that metal-rich K dwarf stars do not show anomalous stellar abundances, as indicated in Feltzing & Gustafsson (1998), and can, with reasonable efforts, be analyzed in order to increase the number of metal-rich stars with useful chemical abundances. With abundance analysis by means of spectrum synthesis and assuming Local Thermodynamic Equilibrium (LTE) the abundances of Na, Si, Ca, Sc, Ti, V, Cr, Fe, Co, Ni, and Nd have been derived. Also ionization balance is satisfied for Fe and Cr after correcting the stellar effective temperatures such that both ionization and excitation equilibrium were satisfied. In addition, spectra from five cool dwarf stars of the Feltzing & Gustafsson (1998) sample have been analyzed with the methods used in this work. They show essentially the same abundance patterns as the new stars in this sample.Comment: 15 pages, latex, 5 figures, Accepted for publication in A&