251 research outputs found
Unifying the First Amendment: Free Exercise, the Provision of Subsidies, and a Public Forum Equivalent
Prognostic Markers in Chondrosarcoma: Evaluation of Cell Proliferation and of Regulators of the Cell Cycle
Purpose. The prognosis, treatment principles and prediction of clinical outcome of patients with chondrosarcoma
currently rest on histologic grading which is somewhat ambiguous due to difficulty in pathologic interpretation of this
neoplasm. Immunohistochemistry, flow cytometry and oncogene/tumor suppressor gene expression have been examined
as alternative indices to predict the biologic behavior of these tumors. Because of partial successes obtained with flow
cytometry and because of the improvement in predicting recurrence offered by examining the S-phase fraction, we
undertook the current study to determine if expression of specific regulators of the cell cycle would act as prognostic
indicators for these patients
NASA-UVA Light Aerospace Alloy and Structures Technology Program: LA(2)ST
The NASA-UVA Light Aerospace Alloy and Structures Technology (LA(2)ST) Program continues a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, Civil Engineering and Applied Mechanics, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. We report on progress achieved between July 1 and December 31, 1992. The objective of the LA(2)ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement advances; and critically, a pool of educated graduate students for aerospace technologies
A reservoir for inverse power law decoherence of a qubit
The exact dynamics of a Jaynes-Cummings model for a qubit interacting with a
continuous distribution of bosons, characterized by a special form of the
spectral density, is evaluated analytically. The special reservoir is designed
to induce anomalous decoherence, resulting in an inverse power law relaxation,
of power 3/2, over an evaluated long time scale. If compared to the
exponential-like relaxation obtained from the original Jaynes-Cummings model
for Lorentzian-type spectral density functions, decoherence is strongly
suppressed. The special reservoir exhibits an upper band edge frequency
coinciding with the qubit transition frequency. Known theoretical models of
photonic band gap media suitable for the realization of the designed reservoir
are proposed.Comment: 5 pages, 2 figure
Prognostic Markers in Chondrosarcoma: Evaluation of Cell Proliferation and of Regulators of the Cell Cycle
NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)
The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program continues a high level of activity. Progress achieved between 1 Jan. and 30 Jun. 1993 is reported. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. The following projects are addressed: environmental fatigue of Al-Li-Cu alloys; mechanisms of localized corrosion and environmental fracture in Al-Cu-Li-Mg-Ag alloy X2095 and compositional variations; the effect of zinc additions on the precipitation and stress corrosion cracking behavior of alloy 8090; hydrogen interactions with Al-Li-Cu alloy 2090 and model alloys; metastable pitting of aluminum alloys; cryogenic fracture toughness of Al-Cu-Li + In alloys; the fracture toughness of Weldalite (TM); elevated temperature cracking of advanced I/M aluminum alloys; response of Ti-1100/SCS-6 composites to thermal exposure; superplastic forming of Weldalite (TM); research to incorporate environmental effects into fracture mechanics fatigue life prediction codes such as NASA FLAGRO; and thermoviscoplastic behavior
NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)
Since 1986, the NASA-Langley Research Center has sponsored the NASA-UVa Light Alloy and Structures Technology (LA2ST) Program at the University of Virginia (UVa). The fundamental objective of the LA2ST program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures. The LA2ST program has aimed to product relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies. The scope of the LA2ST Program is broad. Research areas include: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals and Composites, (2) Aerospace Materials Science, (3) Mechanics of materials for Aerospace Structures, and (4) Thermal Gradient Structures. A substantial series of semi-annual progress reports issued since 1987 documents the technical objectives, experimental or analytical procedures, and detailed results of graduate student research in these topical areas
Beyond single-photon localization at the edge of a Photonic Band Gap
We study spontaneous emission in an atomic ladder system, with both
transitions coupled near-resonantly to the edge of a photonic band gap
continuum. The problem is solved through a recently developed technique and
leads to the formation of a ``two-photon+atom'' bound state with fractional
population trapping in both upper states. In the long-time limit, the atom can
be found excited in a superposition of the upper states and a ``direct''
two-photon process coexists with the stepwise one. The sensitivity of the
effect to the particular form of the density of states is also explored.Comment: to appear in Physical Review
Photon-photon correlations and entanglement in doped photonic crystals
We consider a photonic crystal (PC) doped with four-level atoms whose
intermediate transition is coupled near-resonantly with a photonic band-gap
edge. We show that two photons, each coupled to a different atomic transition
in such atoms, can manifest strong phase or amplitude correlations: One photon
can induce a large phase shift on the other photon or trigger its absorption
and thus operate as an ultrasensitive nonlinear photon-switch. These features
allow the creation of entangled two-photon states and have unique advantages
over previously considered media: (i) no control lasers are needed; (ii) the
system parameters can be chosen to cause full two-photon entanglement via
absorption; (iii) a number of PCs can be combined in a network.Comment: Modified, expanded text; added reference
NASA-UVA light aerospace alloy and structures technology program (LA2ST)
The NASA-UVa Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. Projects are being conducted by graduate students and faculty advisors in the Department of Materials Science and Engineering, as well as in the Department of Civil Engineering and Applied Mechanics, at the University of Virginia. Here, we report on progress achieved between July 1 and December 31, 1994. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies
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