Studies of Work ‘in the Wild’

Computer Supported Cooperative Work (CSCW) -     

Simulation of the submerged energy nozzle-mold water model system using laser-optical and computational fluid dynamics methods

The present work describes quantitative digital particle image velocimetry measurements of a full-scale water model of a thin slab mold. Different casting speeds and two submerged entry nozzles with one and two outlet ports have been investigated. The flow pattern of the single-port nozzle shows a counterclockwise-rotating double vortex that is nearly steady-state but leads to high stationary surface waves. The flow jets out of the two-port nozzle oscillate and produce a transient flow pattern with low wave amplitudes. The amplitudes for the one-port nozzle show a linear variation with the volumetric flow rate. The experimental results lead to a good interpretation of the flow phenomena and are used to validate steady-state numerical simulations with the commercial program, CFX, on the basis of the Reynolds equations. To describe anisotropic turbulence effects, the Reynolds stress model (RSM) is used for the flat single-port nozzle and the standard k-ɛ model for the mold flow. The calculated mean velocities and wave amplitudes, predicted from pressure distribution at the water surface, are generally in the consensus of the experimental data. An erratum to this article is available at .     

Synthesis of enantiomerically pure 1-O-phosphocholine-2-O-acyl-octadecane and 1-O-phosphocholine-2-N-acyl-octadecane

This is the first report on the chemical synthesis of enantiomerically pure R- or S-1-O-phosphocholine-2-O-acyl-octadecanes and R- or S-1-O-phosphocholine-2-N-acyl-octadecanes. From a structural point of view these phospholipids are intermediates between phosphatidylcholine and sphingomyelin. The synthesis of these model compounds is based on R- or S-1.2-O-isopropylidene-glyceraldeyde for chain elongation in a Wittig reaction with pentadecane-triphenylphosphine bromide. The resulting 1.2-O-isopropylidene-octadec-3-en is converted to R- or S-1.2-octadecanediol by catalytic hydrogenation of the double bond and by acidic removal of the isopropylidene protecting group. Tritylation of R- or S-1.2-octadecanediol results in the general intermediates R- or S-1-O-trityl-2-hydroxy-octadecane. These are the key intermediates for the synthesis of the phosphatidylcholine- or sphingomyelin-like end products. R- or S-1-O-phosphocholine-2-O-acyl-octadecane is obtained from the tritylated intermediates via benzylation in position 2, acidic detritylation and conversion of the R- or S-1-hydroxy-2-benzyl-octadecanes to the respective phosphocholines via the phosphoethanolamines. Catalytic hydrogenolysis of the benzyl group results in R- or S-1-O-phosphocholine-2-hydroxy-octadecane, which is converted to the phosphatidylcholine-like end products by acylation. R- or S-1-O-phosphocholine-2-N-acyl-octadecane is obtained from the tritylated intermediate by conversion of the R- or S-2-hydroxy group into the N-phthalimido group, which is achieved by inversion of the configuration using the Mitsunobu reaction with phthalimid. After acidic detritylation, the product is converted to the respective S- or R-1-O-phosphocholine derivative in a similar sequence of reactions. The phthalimido group is converted to the 2-amino group, and acylation results in the sphingomyelin-like end products.     

A Historical View of Studies of Women’s Work

Computer Supported Cooperative Work (CSCW) - This paper places observational studies of women’s work in historical perspective. We present some of the very early studies (carried out in the...     

Comparison of selective cytotoxicity of alkyl lysophospholipids

Alkyl lysophospholipids have been shown to be cytooxic to a number of neoplastic tissues. One, ET-18-OCH₃, has been used to selectively purge leukemic cells from mixtures with normal marrow progenitor cells,in vitro andin vivo. We have measured the 50% inhibitory (IC₅₀) effect of a series of ether, lipids (EL) on leukemic cells (HL60, K562, Daudi, KG-1, KG-1a) and normal marrow progenitor cells. Cells were incubated with varying concentrations of EL for 4 hr and assayed for viability, [³H]thymidine incorporation and clonogenicity in semi-solid media. The effect on protein kinase C (PKC) activity was assayed for each compound. Compounds tested included three glycerophosphocholine analogs-ET-18-OCH₃, ET-16-NHCOCH₃, and BM 41.440. In addition, a lipoidal amine, CP 46665, an ethyleneglycolphospholipid, AEPL, and four single chain alkylphosphocholine analogs, HePC₂, HePC₃, HePC₄ and HePC₆ were also tested. During the period of incubation, the cells remained viable (>70%) as judged by trypan blue dye exclusion. The glycerophosphocholines were the most active and showed the highest therapeutic index. The lipoidal amine was active, but toxic to normal marrow progenitor cells. The ethyleneglycolphospholipid was active against HL60, but not against the other cell lines. The single chain alkylphosphocholine analogs were less active. All of the compounds inhibited PKC activity; however, the glycerophosphocholines were the most inhibitory. Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl Ether Lipids, Tokyo, Japan, May 1989.     

Algal phagostimulants for marine herbivorous gastropods

Methanol extracts of the green algaUlva pertusa contain four kinds of glycerolipids that are active as feeding-stimulants for marine herbivorous gastropods. These compounds are digalactosyldiacylglycerol (DGDG), 1,2-diacylglycerly-4-O-(N,N,N-trimethyl)-homoserine (DGTH), 1-monoacylglyceryl-4'-O-(N,N,N-trimethyl)-homoserine (MGTH), and 6-sulfoquinovosyldiacylglycerol (SQDG). The various gastropods exhibit marked specificity, however, as young abaloneHaliotis discus respond to DGDG and DGTH at minute dosages of 20–30 g/sample zone, but do not respond to 300 g of SQDG, which is a phagostimulant for two other kinds of gastropods,Turbo comutus andOmphalius pfeifferi.Chemical Studies on Phagostimulants for Marine Gastropods. Part VI. For Part V, see Sakata et al. (1986b).     

Feeding-stimulant activity of algal glycerolipids for marine herbivorous gastropods

Phagostimulant activity of glycerolipids such as digalactosyldiacylglycerol (DGDG), 6-sulfoquinovosyldiacylglycerol (SQDG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), etc., have been examined using the Avicel plate method for three kinds of marine herbivorous gastropods, the abaloneHaliotis discus, the turban shellTurbo cornutus, and the topshellOmphalius pfeifferi. DGDG showed strong activity for all the test animals. SQDG was much less active than the other glycerolipids for abalone. The turban shell and the top shell responded more or less sensitively to all tested glycerolipids at doses of 10–20g/sample zone.Chemical Studies on Phagostimulants for Marine Gastropods. Part VIII. For Part VII, see Sakata et al. (1988a).     

Time-of-flight studies on catalytic model reactions

Time-of-flight spectroscopy (TOF) and REMPI-TOF (resonance enhanced multi-photon ionization-TOF) were applied to measure the angular and translational energy distribution, as well as the internal state resolved energy distribution of desorption and reaction products on some model systems. Desorption of hydrogen and deuterium from clean and modified Pd(111) surfaces was studied, where the palladium sample was part of a permeation source. Water formation by reaction of oxygen with hydrogen on palladium was investigated by using different types of hydrogen supply: molecular H₂ exposure and atomic H exposure from the gas phase, as well as H exposure by permeating hydrogen. Vanadium oxide nanostructures on Pd(111) were prepared and the influence on D₂ desorption and D₂O production was investigated with the permeation technique. Additionally, deuterium desorption from sulfur and oxygen covered V(111) and V(100) surfaces was studied by TOF and REMPI-TOF spectroscopy. From the TOF spectra information concerning the reaction and desorption dynamics (activation barriers) could be gained.     

Spezifische Bedarfe bei zahnärztlichen Patienten mit Demenz und ihre ethischen Implikationen

Definition of the problem

The central foundations of successful dental treatment consist of a trustful patient-dentist relationship, the professional and psychosocial expertise of the team treating the patient, and consideration of ethical aspects both during the therapeutic decision-making process and during the subsequent execution of therapy. This is especially true of the dental treatment of (mostly elder) persons with dementia, calling for an in-depth assessment of the various normative implications.

Arguments

In geriatric dentistry in particular, situational dilemmas regarding treatment often arise from specific constellations (e.?g. greatly reduced potential for dental therapy, lack of ability regarding oral hygiene and lack of individual patient responsibility) combined with an acute need for treatment and the necessary involvement of third parties. These dilemmas frequently place additional professional and normative demands on the dentist. The current contribution discusses this specific situation, first by way of theoretical discourse and subsequently with a case-related approach on the basis of two case histories.

Conclusion

It becomes clear here that classic state-of-the-art therapies are replaced by “compromise treatment” in many cases in geriatric dentistry. Such treatment follows divergent diagnostic and therapeutic rules, poses changed requirements in terms of communication and presents specific ethical challenges and pitfalls.