Correlation tracking study for meter-class solar telescope on space shuttle

The theory and expected performance level of correlation trackers used to control the pointing of a solar telescope in space using white light granulation as a target were studied. Three specific trackers were modeled and their performance levels predicted for telescopes of various apertures. The performance of the computer model trackers on computer enhanced granulation photographs was evaluated. Parametric equations for predicting tracker performance are presented

A Cryogenic Helium Pressurization System for the Lunar Excursion Module

No abstract availabl

Magnetic properties of photospheric regions having very low magnetic flux

The magnetic properties of the quiet Sun are investigated using a novel inversion code, FATIMA, based on the Principal Component Analysis of the observed Stokes profiles. The stability and relatively low noise sensitivity of this inversion procedure allows for the systematic inversion of large data sets with very weak polarization signal. Its application to quiet Sun observations of network and internetwork regions reveals that a significant fraction of the quiet Sun contains kilogauss fields (usually with very small filling factors) and confirms that the pixels with weak polarization account for most of the magnetic flux. Mixed polarities in the resolution element are also found to occur more likely as the polarization weakens.Comment: To apapear in ApJ. 39 pages, 12 figures (2 of them are color figures

Quiet Sun magnetic fields from simultaneous inversions of visible and infrared spectropolarimetric observations

We study the quiet Sun magnetic fields using spectropolarimetric observations of the infrared and visible Fe I lines at 6301.5, 6302.5, 15648 and 15653 A. Magnetic field strengths and filling factors are inferred by the simultaneous fit of the observed Stokes profiles under the MISMA hypothesis. The observations cover an intra-network region at the solar disk center. We analyze 2280 Stokes profiles whose polarization signals are above noise in the two spectral ranges, which correspond to 40% of the field of view. Most of these profiles can be reproduced only with a model atmosphere including 3 magnetic components with very different field strengths, which indicates the co-existence of kG and sub-kG fields in our 1.5" resolution elements. We measure an unsigned magnetic flux density of 9.6 G considering the full field of view. Half of the pixels present magnetic fields with mixed polarities in the resolution element. The fraction of mixed polarities increases as the polarization weakens. We compute the probability density function of finding each magnetic field strength. It has a significant contribution of kG field strengths, which concentrates most of the observed magnetic flux and energy. This kG contribution has a preferred magnetic polarity, while the polarity of the weak fields is balanced.Comment: 16 pages and 14 figure

Bank Erosion Study

The Bank Erosion Study was designed to evaluate eroding fast land bank shorelines as contributors of sand, silt and clay and total nitrogen and total phosphorous introduced into the Chesapeake Bay estuarine system. In addition, the extent and effectiveness of erosion control measures were evaluated for selected shoreline reaches. Fastland banks are the uplands along the shorelines that are composed of semi-consolidated sediments. This study evaluates about 2000 miles of primary tidal shoreline in the Virginia portion of the Chesapeake Bay estuarine system for areas of fast land bank erosion. Primary tidal shorelines are those along the main stem of the Chesapeake Bay and the major tributary estuaries. Approximately 383 miles of shoreline comprising 208 shore reaches are included in. the final analysis. These reaches are responsible for 61% of the annual historic sediment volume loading from tidal shoreline erosion. Sediments for selected representative shore reaches were sampled and analyzed for sand, silt, and clay. Volumetric rates of sediment loading for the study shorelines were determined from historical data. Also, the condition of the shorelines were evaluated by analyzing oblique aerial imagery for 1985 and 1990. From the imagery analysis the extent of defensive shoreline structures (i.e. bulkheads, seawall and revetments) and whether the bank was stable or not was determined. Sediment volume loading was considered to be halted where defensive shoreline structures were installed. There was an increase in shoreline defenses of 18% by 1990. This resulted in an annual reduction of sediment loading by 5%. Total nitrogen and total phosphorous loading from eroding fast land bank sediments have been determined to be significant. This study utilized the results of Ibison et al., 1990 which provided average nutrient loading rates for total nitrogen and total phosphorous from eroded fastland bank sediments. The consequent estimated annual reduction in nutrient loading by defended shorelines for 1990 is about 5% for total nitrogen and total phosphorous. Nineteen reaches have been identified as significant contributors of eroding bank sediments and will require further assessment as to the impacts of nutrient loading

The Acclaim Programme in the South Atlantic and Southern Oceans

The ACCLAIM sea level network consists of six coastal tide gauge sites and approximately a dozen bottom pressure stations in the South Atlantic and Southern Oceans. Since 1985, an extensive dataset of regional sea level and bottom pressure measurements has been acquired. This dataset is being employed at POL in a number of scientific analyses and is available to any interested research worker through the World Ocean Circulation Experiment. In this paper, a review is given of the development and status of the ACCLAIM network and the technology installed at each site. Plans are presented for developments over the next 1-2 years

Do UK universities communicate their brands effectively through their websites?

This paper attempts to explore the effectiveness of UK universities’ websites. The area of branding in higher education has received increasing academic investigation, but little work has researched how universities demonstrate their brand promises through their websites. The quest to differentiate through branding can be challenging in the university context, however. It is argued that those institutions that have a strong distinctive image will be in a better position to face a changing future. Employing a multistage methodology, the web pages of twenty UK universities were investigated by using a combination of content and multivariable analysis. Results indicated ‘traditional values’ such as teaching and research were often well communicated in terms of online brand but ‘emotional values’ like social responsibility and the universities’ environments were less consistently communicated, despite their increased topicality. It is therefore suggested that emotional values may offer a basis for possible future online differentiation

Cysteine Modifiers Suggest an Allosteric Inhibitory Site on the CAL PDZ Domain

Protein–protein interactions have become attractive targets for both experimental and therapeutic interventions. The PSD-95/Dlg1/ZO-1 (PDZ) domain is found in a large family of eukaryotic scaffold proteins that plays important roles in intracellular trafficking and localization of many target proteins. Here, we seek inhibitors of the PDZ protein that facilitates post-endocytic degradation of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR): the CFTR-associated ligand (CAL). We develop and validate biochemical screens and identify methyl-3,4-dephostatin (MD) and its analog ethyl-3,4-dephostatin (ED) as CAL PDZ inhibitors. Depending on conditions, MD can bind either covalently or non-covalently. Crystallographic and NMR data confirm that MD attacks a pocket at a site distinct from the canonical peptide-binding groove, and suggests an allosteric connection between target residue Cys319 and the conserved Leu291 in the GLGI motif. MD and ED thus appear to represent the first examples of small-molecule allosteric regulation of PDZ:peptide affinity. Their mechanism of action may exploit the known conformational plasticity of the PDZ domains and suggests that allosteric modulation may represent a strategy for targeting of this family of protein–protein binding modules