3,548 research outputs found
Data management study, volume 5. Appendix I - Contract or data package overall management /MA/, scheduling /SC/, MANNING and financial /MF/ Final report
Overall management, scheduling, manpower, and financial aspects of Voyager data managemen
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A point mutation of integrin beta 1 subunit blocks binding of alpha 5 beta 1 to fibronectin and invasin but not recruitment to adhesion plaques.
A point mutation in a highly conserved region of the beta 1 subunit, Asp130 to Ala (D130A) substitution, abrogates the Arg-Gly-Asp (RGD)-dependent binding of alpha 5 beta 1 to fibronectin (FN) without disrupting gross structure or heterodimer assembly. The D130A mutation also interferes with binding to invasin, a ligand that lacks RGD sequence. In spite of the lack of detectable FN binding by alpha 5 beta 1(D130A), it was recruited to adhesion plaques formed on FN by endogenous hamster receptors. Thus, intact ligand binding function is not required for recruitment of alpha 5 beta 1 to adhesion plaques. Overexpression of beta 1(D130A) partially interfered with endogenous alpha 5 beta 1 function, thus defining a dominant negative beta 1 integrin mutation
Measurement of stopping beam distributions in the PIBETA detector
Precise calculation of the geometrical acceptance of a large solid angle
detector with an integrated stopping target relies on precise knowledge of the
beam geometry. We describe four alternative methods that we used to measure the
beam stopping distributions in the PIBETA detector active target: (i) light
response of segmented target elements to incident beam particles, (ii)
back-tracking of charged particles from pi+ and mu+ decays using multi-wire
proportional chambers, (iii) volume distribution of the Dalitz decay
(pi0->gamma e+e-) event vertices, and (iv) the opening angle distribution of
two pi0 photons originating from the beta decay of pi+ at rest. We demonstrate
consistent results obtained by these four independent approaches and show how
particular beam stopping distributions affect the detector's geometrical
acceptance.Comment: 38 pages, 16 postscript figures, 2 tables, LaTeX, submitted to Nucl.
Instrum. Meth.
Chronology of Range Expansion of the Coyote, Canis latrans, in New York
Coyotes (Canis latrans) were historically restricted to central North America. In less than two centuries, however, Coyotes have colonized most of the continent, including much of northeastern North America. Better understanding causes and proximate mechanisms of this expansion requires a detailed understanding of how Coyotes colonized areas on a fine scale. We examined the establishment of Coyotes in the State of New York by collecting and analyzing reports of their first occurrence throughout the state over the past century, and creating a detailed map of range expansion. Coyotes first entered New York from the north, circled the Adirondack region prior to colonizing it, and then expanded southward and westward at ca. 78-90 km/decade. The revealed pattern lends little support to the hypotheses that the range expansion is attributable to translocations and releases, or that Coyotes were historically present in the region and only recently expanded in numbers. Rather, the data suggest a correlative relationship between anthropogenic land use and Coyote range expansion
Charging-driven coarsening and melting of a colloidal nanoparticle monolayer at an ionic liquid-vacuum interface
We induce and investigate the coarsening and melting dynamics of an initially
static nanoparticle colloidal monolayer at an ionic liquid-vacuum interface,
driven by a focused, scanning electron beam. Coarsening occurs through grain
interface migration and larger-scale motions such as grain rotations, often
facilitated by sliding dislocations. The progressive decrease in area fraction
that drives melting of the monolayer is explained using an electrowetting model
whereby particles at the interface are solvated once their accumulating charge
recruits sufficient counterions to subsume the particle. Subject to stochastic
particle removal from the monolayer, melting is recapitulated in simulations
with a Lennard-Jones potential. This new driving mechanism for colloidal
systems, whose dynamical timescales we show can be controlled with the
accelerating voltage, opens the possibility to manipulate particle interactions
dynamically without need to vary particle intrinsic properties or surface
treatments. Furthermore, the decrease in particle size availed by electron
imaging presents opportunities to observe force and time scales in a
lesser-explored regime intermediate between typical colloidal and molecular
systems.Comment: 14 pages, 6 figures, also see supplementary ancilliary fil
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