29,093 research outputs found
Depletion potentials near geometrically structured substrates
Using the recently developed so-called White Bear version of Rosenfeld's
Fundamental Measure Theory we calculate the depletion potentials between a
hard-sphere colloidal particle in a solvent of small hard spheres and simple
models of geometrically structured substrates: a right-angled wedge or edge. In
the wedge geometry, there is a strong attraction beyond the corresponding one
near a planar wall that significantly influences the structure of colloidal
suspensions in wedges. In accordance with an experimental study, for the edge
geometry we find a free energy barrier of the order of several which
repels a big colloidal particle from the edge.Comment: 7 pages, 7 figure
Pairing in the Framework of the Unitary Correlation Operator Method (UCOM): Hartree-Fock-Bogoliubov Calculations
In this first in a series of articles, we apply effective interactions
derived by the Unitary Correlation Operator Method (UCOM) to the description of
open-shell nuclei, using a self-consistent Hartree-Fock-Bogoliubov framework to
account for pairing correlations. To disentangle the particle-hole and
particle-particle channels and assess the pairing properties of \VUCOM, we
consider hybrid calculations using the phenomenological Gogny D1S interaction
to derive the particle-hole mean field. In the main part of this article, we
perform calculations of the tin isotopic chain using \VUCOM in both the
particle-hole and particle-particle channels. We study the interplay of both
channels, and discuss the impact of non-central and non-local terms in
realistic interactions as well as the frequently used restriction of pairing
interactions to the partial wave. The treatment of the center-of-mass
motion and its effect on theoretical pairing gaps is assessed independently of
the used interactions.Comment: 14 pages, 10 figures, to appear in Phys. Rev. C, title modified
accordingl
Earth-based radar contribution to Mars sample return
Earth based radar has often observed planets decades before space missions and provided valuable information leading to the success of those missions. As a Mars Sample Return Mission is contemplated, possible measurements by earth based radar should be reviewed. Earth based radars provide measurements of topography, bulk dielectric constants, rms slopes, and surface rock populations. All of these measurement will be valuable to a Mars Sample Return Mission. The 1988 and 1990 oppositions provide excellent positions for the extension of southern earth based coverage of Mars to -25 deg, while oppositions for the rest of the 1990's will provide coverage of northern latitudes to 25 deg
Thermal environment
Human tolerance in thermal environment, thermal physiology of space clothing, and biothermal considerations in space cabin desig
Science Verification Results from PMAS
PMAS, the Potsdam Multi-Aperture Spectrophotometer, is a new integral field
instrument which was commissioned at the Calar Alto 3.5m Telescope in May 2001.
We report on results obtained from a science verification run in October 2001.
We present observations of the low-metallicity blue compact dwarf galaxy
SBS0335-052, the ultra-luminous X-ray Source X-1 in the Holmberg II galaxy, the
quadruple gravitational lens system Q2237+0305 (the "Einstein Cross"), the
Galactic planetary nebula NGC7027, and extragalactic planetary nebulae in M31.
PMAS is now available as a common user instrument at Calar Alto Observatory.Comment: 4 pages, 9 figures (attached in JPEG format), Euro3D Science Workshop
Proceedings, held in Cambridge May 21-23, 2003, to appear in AN (accepted
Spinorial Characterizations of Surfaces into 3-dimensional pseudo-Riemannian Space Forms
We give a spinorial characterization of isometrically immersed surfaces of
arbitrary signature into 3-dimensional pseudo-Riemannian space forms. For
Lorentzian surfaces, this generalizes a recent work of the first author in
to other Lorentzian space forms. We also characterize
immersions of Riemannian surfaces in these spaces. From this we can deduce
analogous results for timelike immersions of Lorentzian surfaces in space forms
of corresponding signature, as well as for spacelike and timelike immersions of
surfaces of signature (0,2), hence achieving a complete spinorial description
for this class of pseudo-Riemannian immersions.Comment: 9 page
Increasing Ultrasound-Guided Thyroid Biopsy Yield
Objectives: Conduct Plan-Do-Study-Act (PDSA) performance improvement project to improve thyroid biopsy yield Short Term\u3ereduce unsuccessful biopsies by 50% Long-Term\u3eeliminate unsuccessful biopsieshttps://jdc.jefferson.edu/patientsafetyposters/1064/thumbnail.jp
Stable marriage and roommates problems with restricted edges: complexity and approximability
In the Stable Marriage and Roommates problems, a set of agents is given, each of them having a strictly ordered preference list over some or all of the other agents. A matching is a set of disjoint pairs of mutually acceptable agents. If any two agents mutually prefer each other to their partner, then they block the matching, otherwise, the matching is said to be stable. We investigate the complexity of finding a solution satisfying additional constraints on restricted pairs of agents. Restricted pairs can be either forced or forbidden. A stable solution must contain all of the forced pairs, while it must contain none of the forbidden pairs.
Dias et al. (2003) gave a polynomial-time algorithm to decide whether such a solution exists in the presence of restricted edges. If the answer is no, one might look for a solution close to optimal. Since optimality in this context means that the matching is stable and satisfies all constraints on restricted pairs, there are two ways of relaxing the constraints by permitting a solution to: (1) be blocked by as few as possible pairs, or (2) violate as few as possible constraints n restricted pairs.
Our main theorems prove that for the (bipartite) Stable Marriage problem, case (1) leads to View the MathML source-hardness and inapproximability results, whilst case (2) can be solved in polynomial time. For non-bipartite Stable Roommates instances, case (2) yields an View the MathML source-hard but (under some cardinality assumptions) 2-approximable problem. In the case of View the MathML source-hard problems, we also discuss polynomially solvable special cases, arising from restrictions on the lengths of the preference lists, or upper bounds on the numbers of restricted pairs
- …