Investigation of light scattering in high reflecting pigmented coatings quarterly report, 1 may - 1 aug. 1965

Application of light scattering theories to highly pigmented coating

X-RAY STRUCTURAL STUDIES ON 3 ANALOGS OF THE ALPHA-ANOMER OF THE ANTITUMOR ANTIBIOTIC SHOWDOMYCIN - DIFFERENTIAL RING-PUCKERING EFFECTS OF HYDROXYL SUGAR SUBSTITUENTS IN LYXO AND ARABINO CONFIGURATIONS

The crystal structures of three a-analogues of the anititumour antibiotic showdomycin (1) have been determined at room temperature. They are 2-(a-D-2'- deoxyribofuranosyl)maleimide (2), 2-(a-D-arabinofuranosyl) maleimide (3) and 2-(a-D-lyxofuranosyl)- maleimide (4). The structures were refined to R factors of 0-039, 0-042 and 0-029 for 971, 1025 and 716 observed reflections. The conformational properties of the sugar rings are discussed in detail, in relation to the differing hydroxyl group substitutions. Compounds (2) and (3) have CY-endo, C4"-exo and CY-endo ring puckers, whereas (3) has C2"-endo, C l'-exo puckers. Compound (3) has an intramolecular hydrogen bond between the 05' and 02' hydroxyl groups. This and the sugar pucker difference are in accord with NMR chemical shift data for the O5' and O2' protons. Crystal data: compound (2), C9H11NOs, orthorhombic, P212~21, a = 5-916 (1), b = 8-191 (1), c = 19.691 (3) A, Z = 4; compound (3), C9HIINO6, orthorhombic, P212121, a = 6.785 (1), b = 8.006 (1), c = 17.564 (2) A, Z= 4; compound (4), C9HI1NO6, monoclinic, P2~, a = 8.681 (1), b = 5.135 (1), c= 11-364 (1) A, Z= 2

Analysis of stratospheric ozone, temperature, and minor constituent data

The objective of this research is to use available satellite measurements of temperature and constituent concentrations to test the conceptual picture of stratospheric chemistry and transport. This was originally broken down into two sub-goals: first, to use the constituent data to search for critical tests of our understanding of stratospheric chemistry and second, to examine constituent transport processes emphasizing interactions with chemistry on various time scales. A third important goal which has evolved is to use the available solar backscattered ultraviolet (SBUV) and Total Ozone Mapping Spectrometer (TOMS) data from Nimbus 7 to describe the morphology of recent changes in Antarctic and global ozone with emphasis on searching for constraints to theories. The major effort now being pursued relative to the two original goals is our effort as a theoretical team for the Arctic Airborne Stratospheric Expedition (AASE). Our effort for the AASE is based on the 3D transport and chemistry model at Goddard. Our goal is to use this model to place the results from the mission data in a regional and global context. Specifically, we set out to make model runs starting in late December and running through March of 1989, both with and without heterogeneous chemistry. The transport is to be carried out using dynamical fields from a 4D data assimilation model being developed under separate funding from this task. We have successfully carried out a series of single constituent transport experiments. One of the things demonstrated by these runs was the difficulty in obtaining observed low N2O abundances in the vortex without simultaneously obtaining very high ozone values. Because the runs start in late December, this difficulty arises in the attempt to define consistent initial conditions for the 3D model. To accomplish a consistent set of initial conditions, we are using the 2D photochemistry-transport model of Jackman and Douglass and mapping in potential temperature, potential vorticity space as developed by Schoeberl and coworkers

Trends in stratospheric minor constituents

Photochemical models predict that increasing source gas concentrations are also expected to lead to changes in the concentrations of both catalytically active radical species (such as NO2, ClO, and OH) and inactive reservoir species (such as HNO3, HCl, and H2O). For simplicity, we will refer to all these as trace species. Those species that are expected to have increasing concentration levels are investigated. Additionally, the trace species concentration levels are monitored for unexpected changes on the basis of the measure increase in source gases. Carrying out these investigations is difficult due to the limited data base of measurements of stratospheric trace species. In situ measurements are made only infrequently, and there are few satelliteborne measurements, most over a time space insufficient for trend determination. Instead, ground-based measurements of column content must be used for many species, and interpretation is complicated by contributions from the troposphere or mesosphere or both. In this chapter, we examine existing measurements as published or tabulated

The devil is in the third year: a longitudinal study of erosion of empathy in medical school.

PURPOSE: This longitudinal study was designed to examine changes in medical students\u27 empathy during medical school and to determine when the most significant changes occur. METHOD: Four hundred fifty-six students who entered Jefferson Medical College in 2002 (n = 227) and 2004 (n = 229) completed the Jefferson Scale of Physician Empathy at five different times: at entry into medical school on orientation day and subsequently at the end of each academic year. Statistical analyses were performed for the entire cohort, as well as for the matched cohort (participants who identified themselves at all five test administrations) and the unmatched cohort (participants who did not identify themselves in all five test administrations). RESULTS: Statistical analyses showed that empathy scores did not change significantly during the first two years of medical school. However, a significant decline in empathy scores was observed at the end of the third year which persisted until graduation. Findings were similar for the matched cohort (n = 121) and for the rest of the sample (unmatched cohort, n = 335). Patterns of decline in empathy scores were similar for men and women and across specialties. CONCLUSIONS: It is concluded that a significant decline in empathy occurs during the third year of medical school. It is ironic that the erosion of empathy occurs during a time when the curriculum is shifting toward patient-care activities; this is when empathy is most essential. Implications for retaining and enhancing empathy are discussed