9,750 research outputs found
Gas flows through shallow T-junctions and parallel microchannel networks
We apply a recent extension of the Hele-Shaw scheme to analyze steady compressible viscous flows
through micro T-junctions. The linearity of the problem in terms of an appropriately defined
quadratic form of the pressure facilitates the definition of the viscous resistance of the configuration,
relating the gas mass-flow rate to entrance and exit conditions. Furthermore, under rather mild
restrictions, the performance of complex microchannel networks may be estimated through
superposition of the contributions of multiple basic junction elements. This procedure is applied to
an optimization model problem of a parallel microchannel network. The analysis and results are
readily adaptable to incompressible flows
Munsell colour notation in ceramic description: an experiment
Archaeologists are making increased use of standardised colour descriptions for material they excavate and study, generally employing the Munsell colour system (Munsell 1966). Readings of soil colours are common practice on most excavations, where they may have significance (at least within small areas) for differentiating soil types. Elsewhere standard colour descriptions are found most frequently applied to pottery, where it is felt necessary to provide accurate descriptions of fabric, surfaces, or decoration
Highly Mutable Linker Regions Regulate HIV-1 Rev Function and Stability.
HIV-1 Rev is an essential viral regulatory protein that facilitates the nuclear export of intron-containing viral mRNAs. It is organized into structured, functionally well-characterized motifs joined by less understood linker regions. Our recent competitive deep mutational scanning study confirmed many known constraints in Rev's established motifs, but also identified positions of mutational plasticity, most notably in surrounding linker regions. Here, we probe the mutational limits of these linkers by testing the activities of multiple truncation and mass substitution mutations. We find that these regions possess previously unknown structural, functional or regulatory roles, not apparent from systematic point mutational approaches. Specifically, the N- and C-termini of Rev contribute to protein stability; mutations in a turn that connects the two main helices of Rev have different effects in different contexts; and a linker region which connects the second helix of Rev to its nuclear export sequence has structural requirements for function. Thus, Rev function extends beyond its characterized motifs, and is tuned by determinants within seemingly plastic portions of its sequence. Additionally, Rev's ability to tolerate many of these massive truncations and substitutions illustrates the overall mutational and functional robustness inherent in this viral protein
A Dependence of Hadron Production in Inelastic Muon Scattering and Dimuon Production by Protons
The A dependence of the production of hadrons in inelastic muon scattering
and of the production of dimuons in high proton interactions are simply
related. Feynman x distributions and z scaling distributions in nuclei are
compared with energy loss models. Suggestions for new data analyses are
presented.Comment: 14pp +13 figures, UPR report 607T (available from
ftp://dept.physics.upenn.edu/muhad
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