NASA space station software standards issues

The selection and application of software standards present the NASA Space Station Program with the opportunity to serve as a pacesetter for the United States software in the area of software standards. The strengths and weaknesses of each of the NASA defined software standards issues are summerized and discussed. Several significant standards issues are offered for NASA consideration. A challenge is presented for the NASA Space Station Program to serve as a pacesetter for the U.S. Software Industry through: (1) Management commitment to software standards; (2) Overall program participation in software standards; and (3) Employment of the best available technology to support software standard

Maintenance and Cure-Jones Act-Seaman Going and Coming from Ship Held in Service of Ship-Shipowner Held to Accept Duty for Safe Transportation in Providing Travel Pay and Attempting to Control Transportation. Williamson v. Western Pacific Dredging Corp. (D. Ore. 1969)

This recent case discusses Williamson v. Western Pacific Dredging Corp. (D. Ore. 1969)

Formation of droplets of alternating composition in microfluidic channels and applications to indexing of concentrations in droplet-based assays

For screening the conditions for a reaction by using droplets (or plugs) as microreactors, the composition of the droplets must be indexed. Indexing here refers to measuring the concentration of a solute by addition of a marker, either internal or external. Indexing may be performed by forming droplet pairs, where in each pair the first droplet is used to conduct the reaction, and the second droplet is used to index the composition of the first droplet. This paper characterizes a method for creating droplet pairs by generating alternating droplets, of two sets of aqueous solutions in a flow of immiscible carrier fluid within PDMS and glass microfluidic channels. The paper also demonstrates that the technique can be used to index the composition of the droplets, and this application is illustrated by screening conditions of protein crystallization. The fluid properties required to form the steady flow of the alternating droplets in a microchannel were characterized as a function of the capillary number Ca and water fraction. Four regimes were observed. At the lowest values of Ca, the droplets of the two streams coalesced; at intermediate values of Ca the alternating droplets formed reliably. At even higher values of Ca, shear forces dominated and caused formation of droplets that were smaller than the cross-sectional dimension of the channel; at the highest values of Ca, coflowing laminar streams of the two immiscible fluids formed. In addition to screening of protein crystallization conditions, understanding of the fluid flow in this system may extend this indexing approach to other chemical and biological assays performed on a microfluidic chip

Comment mesurer les progrès de la lecture?

New observations of Neptune’s clouds in the near infrared were acquired in October 2013 with SINFONI on ESO’s Very Large Telescope (VLT) in Chile. SINFONI is an Integral Field Unit spectrometer returning a 64 × 64 pixel image with 2048 wavelengths. Image cubes in the J-band (1.09 – 1.41 μm) and H-band (1.43 – 1.87 μm) were obtained at spatial resolutions of 0.1″and 0.025″per pixel, while SINFONI’s adaptive optics provided an effective resolution of approximately 0.1″. Image cubes were obtained at the start and end of three successive nights to monitor the temporal development of discrete clouds both at short timescales (i.e. during a single night) as well as over the longer period of the three-day observing run. These observations were compared with similar H-band observations obtained in September 2009 with the NIFS Integral Field Unit spectrometer on the Gemini-North telescope in Hawaii, previously reported by Irwin et al., Icarus 216, 141-158, 2011, and previously unreported Gemini/NIFS observations at lower spatial resolution made in 2011. We find both similarities and differences between these observations, spaced over four years. The same overall cloud structure is seen with high, bright clouds visible at mid-latitudes (30 – 40°N,S), with slightly lower clouds observed at lower latitudes, together with small discrete clouds seen circling the pole at a latitude of approximately 60°S. However, while discrete clouds were visible at this latitude at both the main cloud deck level (at 2–3 bars) and in the upper troposphere (100–500mb) in 2009, no distinct deep (2–3 bar), discrete circumpolar clouds were visible in 2013, although some deep clouds were seen at the southern edge of the main cloud belt at 30–40°S, which have not been observed before. The nature of the deep sub-polar discrete clouds observed in 2009 is intriguing. While it is possible that in 2013 these deeper clouds were masked by faster moving, overlying features, we consider that it is unlikely that this should have happened in 2013, but not in 2009 when the upper-cloud activity was generally similar. Meanwhile, the deep clouds seen at the southern edge of the main cloud belt at 30 – 40°S in 2013, should also have been detectable in 2009, but were not seen. Hence, these observations may have detected a real temporal variation in the occurrence of Neptune’s deep clouds, pointing to underlying variability in the convective activity at the pressure of the main cloud deck at 2–3 bars near Neptune’s south pole and also in the main observable cloud belt at 30 – 40°S.</p

Multi-step synthesis of nanoparticles performed on millisecond time scale in a microfluidic droplet-based system

This paper reports a plug-based, microfluidic method for performing multi-step chemical reactions with millisecond time-control. It builds upon a previously reported method where aqueous reagents were injected into a flow of immiscible fluid (fluorocarbons) (H. Song et al., Angew. Chem. Int. Ed., 2003, 42, 768). The aqueous reagents formed plugs – droplets surrounded and transported by the immiscible fluid. Winding channels rapidly mixed the reagents in droplets. This paper shows that further stages of the reaction could be initiated by flowing additional reagent streams directly into the droplets of initial reaction mixture. The conditions necessary for an aqueous stream to merge with aqueous droplets were characterized. The Capillary number could be used to predict the behavior of the two-phase flow at the merging junction. By transporting solid reaction products in droplets, the products were kept from aggregating on the walls of the microchannels. To demonstrate the utility of this microfluidic method it was used to synthesize colloidal CdS and CdS/CdSe core-shell nanoparticles

A Droplet-Based, Composite PDMS/Glass Capillary Microfluidic System for Evaluating Protein Crystallization Conditions by Microbatch and Vapor-Diffusion Methods with On-Chip X-Ray Diffraction

On-chip protein crystallization and diffraction: Proteins can be crystallized in nanoliter volumes by using both microbatch and vapor-diffusion techniques inside composite PDMS/glass microfluidic devices (PDMS=polydimethylsiloxane). The quality of crystals can be assessed directly by on-chip X-ray diffraction