Splanchnic Removal of Atrial Natriuretic Factor (ANF) in Man

In order to assess the effect of food ingestion on splanchnic disposal of human alpha-atrial natriuretic peptide (ANF), hepatic-intestinal removal of ANF was determined before and after a test meal. Hepatic venous and arterial plasma samples were obtained from six subjects, most of whom had only disorders of minor degree. Hepatic blood flow (HBF) increased significantly after meal ingestion (1.10 ± 0.17 [SEM] to 1.51 ± 0.26 L/min, P < .01). Baseline arterial ANF (10.9 ± 3.1 pmol/L) did not change significantly. In contrast, hepatic venous ANF increased after meal intake (5.7 ± 2.0 to 8.4 ± 1.9 pmol/L, P < .05), and accordingly the splanchnic fractional extraction decreased (0.53 ± 0.09 to 0.35 ± 0.08), although this was not statistically significant. Splanchnic clearance of ANF increased from 347 ± 90 mL/min to a maximal value of 615 ± 158 mL/min (P < .05). Splanchnic removal of ANF was 3.0 ± 0.5 pmol/min before and increased to a maximum value (7.1 ± 2.2 pmol/min, P < .05) 35 minutes after ingestion of the meal. Our results showed enhanced splanchnic removal of ANF after food intake. This is due to increased hepatic-intestinal clearance of the peptide consequent on increased splanchnic blood flow, rather than altered fractional extraction of ANF

Toward quantification of strain-related mosaicity in shocked lunar and terrestrial plagioclase by in situ micro-X-ray diffraction

Studies of shock metamorphism of feldspar typically rely on qualitative petrographic observations, which, while providing invaluable information, can be difficult to interpret. Shocked feldspars, therefore, are now being studied in greater detail by various groups using a variety of modern techniques. We apply in situ micro-X-ray diffraction (μXRD) to shocked lunar and terrestrial plagioclase feldspar to contribute to the development of a quantitative scale of shock deformation for the feldspar group. Andesine and labradorite from the Mistastin Lake impact structure, Labrador, Canada, and anorthite from Earth's Moon, returned during the Apollo program, were examined using optical petrography and assigned to subgroups of the optical shock level classification system of Stöffler (1971). Two-dimensional μXRD patterns from the same samples revealed increased peak broadening in the chi dimension (χ), due to strain-related mosaicity, with increased optical signs of deformation. Measurement of the full width at half maximum along χ (FWHMχ) of these peaks provides a quantitative way to measure strain-related mosaicity in plagioclase feldspar as a proxy for shock level

Shock effects in plagioclase feldspar from the Mistastin Lake impact structure, Canada

Shock metamorphism, caused by hypervelocity impact, is a poorly understood process in feldspar due to the complexity of the crystal structure, the relative ease of weathering, and chemical variations, making optical studies of shocked feldspars challenging. Understanding shock metamorphism in feldspars, and plagioclase in particular, is vital for understanding the history of Earth's moon, Mars, and many other planetary bodies. We present here a comprehensive study of shock effects in andesine and labradorite from the Mistastin Lake impact structure, Labrador, Canada. Samples from a range of different settings were studied, from in situ central uplift materials to clasts from various breccias and impact melt rocks. Evidence of shock metamorphism includes undulose extinction, offset twins, kinked twins, alternate twin deformation, and partial to complete transformation to diaplectic plagioclase glass. In some cases, isotropization of alternating twin lamellae was observed. Planar deformation features (PDFs) are notably absent in the plagioclase, even when present in neighboring quartz grains. It is notable that various microlites, twin planes, and compositionally different lamellae could easily be mistaken for PDFs and so care must be taken. A pseudomorphous zeolite phase (levyne-Ca) was identified as a replacement mineral of diaplectic feldspar glass in some samples, which could, in some instances, also be potentially mistaken for PDFs. We suggest that the lack of PDFs in plagioclase could be due to a combination of structural controls relating to the crystal structure of different feldspars and/or the presence of existing planes of weakness in the form of twin and cleavage planes

The Relationship between Leadership Traits, Market Orientation and Corporate Culture on Customer’s Retention on Quasi-Government Organizations in The U.S Virgin Islands

This paper examines the relationships between transformational leadership, market orientation and corporate culture in customer retention in quasi-government organizations. The purpose of this research is to identify and examine this synergistic fit that was not researched as a combination in previous literature. In recent years, small business owners have realized the importance of strategic leadership in achieving both shareholders and stakeholders interest. A comparison of quasi-government organizations reveals that, in the U.S. Virgin Islands, market orientation leads to higher customer retention, knowledge competence, enhanced market-based innovations and higher profit margins. A hybrid of the three organizational phenomenon is critical findings of this study. This paper will further examine the three pillows associated profitable organizations: leadership, market orientation, and corporate culture. The findings of this research will have significant implications for strategic business unit’s managers who relies on economic forecast to maximize financial returns in quasi-government agencies

Proton-induced noise in digicons

The Space Telescope, which carries four Digicons, will pass several times per day through a low-altitude portion of the radiation belt called the South Atlantic Anomaly. This is expected to create interference in what is otherwise anticipated to be a noise-free device. Two essential components of the Digicon, the semiconductor diode array and the UV transmitting window, generate noise when subjected to medium-energy proton radiation, a primary component of the belt. These trapped protons, having energies ranging from 2 to 400 Mev and fluences at the Digicon up to 4,000 P+/sec-sq cm, pass through both the window and the diode array, depositing energy in each. In order to evaluate the effect of these protons, engineering test models of Digicon tubes to be flown on the High Resolution Spectrograph were irradiated with low-flux monoenergetic proton beams at the University of Maryland cyclotron. Electron-hole pairs produced by the protons passing through the diodes or the surrounding bulk caused a background count rate. This is the result of holes diffusing over a distance of many diode spacings, causing counts to be triggered simultaneously in the output circuits of several adjacent diodes. Pulse-height spectra of these proton-induced counts indicate that most of the bulk-related counts overlap the single photoelectron peak. A geometrical model will be presented of the charge collection characteristics of the diode array that accounts for most of the observed effects

Video Guidance, Landing, and Imaging system (VGLIS) for space missions

The feasibility of an autonomous video guidance system that is capable of observing a planetary surface during terminal descent and selecting the most acceptable landing site was demonstrated. The system was breadboarded and "flown" on a physical simulator consisting of a control panel and monitor, a dynamic simulator, and a PDP-9 computer. The breadboard VGLIS consisted of an image dissector camera and the appropriate processing logic. Results are reported