1,449 research outputs found
Shuttle Return-to-Flight IH-108 Aerothermal Test at CUBRC - Flow Field Calibration and CFD
This paper discusses one specific aspect of the Shuttle Retrun-To-Flight IH-108 Aerothermal Test at Calspan-University of Buffalo Research Center (CUBRC), the test flow field calibration. It showed the versatility of the CUBRC Large Energy National Shock Tunnel (LENS) II wind tunnel for an aerothermal test with unique and demanding requirements. CFD analyses were used effectively to extend the test range at the low end of the Mach range. It demonstrated how ground test facility and CFD synergy can be utilitzed iteratively to enhance the confidence in the fedility of both tools. It addressed the lingering concerns of the aerothermal community on use of inpulse facility and CFD analysis. At the conclusion of the test program, members from the NASA Marshall (MSFC), CUBRC and USA (United Space Alliance) Consultants (The Grey Beards) were asked to independently verify the flight scaling data generated by Boeing for flight certification of the re-designed external tank (ET) components. The blind test comparison showed very good results
Creation of the universe with a stealth scalar field
The stealth scalar field is a non-trivial configuration without any
back-reaction to geometry, which is characteristic for non-minimally coupled
scalar fields. Studying the creation probability of the de Sitter universe with
a stealth scalar field by the Hartle and Hawking's semi-classical method, we
show that the effect of the stealth field can be significant. For the class of
scalar fields we consider, creation with a stealth field is possible for a
discrete value of the coupling constant and its creation probability is always
less than that with a trivial scalar field. However, those creation rates can
be almost the same depending on the parameters of the theory.Comment: 7 pages; v2, references added; v3, creation of the open universe
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Energy Extraction from Higher Dimensional Black Holes and Black Rings
We analyze the energy extraction by the Penrose process in higher dimensions.
Our result shows the efficiency of the process from higher dimensional black
holes and black rings can be rather high compared with than that in four
dimensional Kerr black hole. In particular, if one rotation parameter vanishes,
the maximum efficiency becomes infinitely large because the angular momentum is
not bounded from above. We also apply a catastrophe theory to analyze the
stability of black rings. It indicates a branch of black rings with higher
rotational energy is unstable, which should be a different type of instability
from the Gregory-Laflamme's one.Comment: 11 pages, 7 figure
Species Abundance Patterns in Complex Evolutionary Dynamics
An analytic theory of species abundance patterns (SAPs) in biological
networks is presented. The theory is based on multispecies replicator dynamics
equivalent to the Lotka-Volterra equation, with diverse interspecies
interactions. Various SAPs observed in nature are derived from a single
parameter. The abundance distribution is formed like a widely observed
left-skewed lognormal distribution. As the model has a general form, the result
can be applied to similar patterns in other complex biological networks, e.g.
gene expression.Comment: 4 pages, 3 figures. Physical Review Letters, in pres
Cosmic Colored Black Holes
We present spherically symmetric static solutions (a particle-like solution
and a black hole solution) in the Einstein-Yang-Mills system with a
cosmological constant.Although their gravitational structures are locally
similar to those of the Bartnik-McKinnon particles or the colored black holes,
the asymptotic behavior becomes quite different because of the existence of a
cosmological horizon. We also discuss their stability by means of a catastrophe
theory as well as a linear perturbation analysis and find the number of
unstable modes.Comment: 12 pages, latex, 4 figures (available upon request
Gauge-invariant gluon mass, infrared Abelian dominance and stability of magnetic vacuum
We give an argument for deriving analytically the infrared ``Abelian''
dominance in a gauge invariant way for the Wilson loop average in SU(2)
Yang--Mills theory. In other words, we propose a possible mechanism for
realizing the dynamical Abelian projection in the SU(2) gauge-invariant manner
without breaking color symmetry. This supports validity of the dual
superconductivity picture for quark confinement. We also discuss the stability
of the vacuum with magnetic condensation as a by-product of this result.Comment: 25 pages, 3 figures (4 eps files); version accepted for publication
in Phys.Rev.D; One paragraph is added at each end of sections 3,4 and 5 for
comparing the analytical result with the lattice results of my group based on
the new formulation, together with the results in the conventional MAG if
available. footnote 4 is added, and a reference is added. A number of
sentences and phrases are improve
Backflow and dissipation during the quantum decay of a metastable Fermi liquid
The particle current in a metastable Fermi liquid against a first-order phase
transition is calculated at zero temperature. During fluctuations of a droplet
of the stable phase, in accordance with the conservation law, not only does an
unperturbed current arise from the continuity at the boundary, but a backflow
is induced by the density response. Quasiparticles carrying these currents are
scattered by the boundary, yielding a dissipative backflow around the droplet.
An energy of the hydrodynamic mass flow of the liquid and a friction force
exerted on the droplet by the quasiparticles have been obtained in terms of a
potential of their interaction with the droplet.Comment: 5 pages (REVTeX), to be published in Phys. Rev.
Radiosensitization of gliomas by intracellular generation of 5-fluorouracil potentiates prodrug activator gene therapy with a retroviral replicating vector.
A tumor-selective non-lytic retroviral replicating vector (RRV), Toca 511, and an extended-release formulation of 5-fluorocytosine (5-FC), Toca FC, are currently being evaluated in clinical trials in patients with recurrent high-grade glioma (NCT01156584, NCT01470794 and NCT01985256). Tumor-selective propagation of this RRV enables highly efficient transduction of glioma cells with cytosine deaminase (CD), which serves as a prodrug activator for conversion of the anti-fungal prodrug 5-FC to the anti-cancer drug 5-fluorouracil (5-FU) directly within the infected cells. We investigated whether, in addition to its direct cytotoxic effects, 5-FU generated intracellularly by RRV-mediated CD/5-FC prodrug activator gene therapy could also act as a radiosensitizing agent. Efficient transduction by RRV and expression of CD were confirmed in the highly aggressive, radioresistant human glioblastoma cell line U87EGFRvIII and its parental cell line U87MG (U87). RRV-transduced cells showed significant radiosensitization even after transient exposure to 5-FC. This was confirmed both in vitro by a clonogenic colony survival assay and in vivo by bioluminescence imaging analysis. These results provide a convincing rationale for development of tumor-targeted radiosensitization strategies utilizing the tumor-selective replicative capability of RRV, and incorporation of radiation therapy into future clinical trials evaluating Toca 511 and Toca FC in brain tumor patients
Temozolomide combined with irinotecan caused regression in an adult pleomorphic rhabdomyosarcoma patient-derived orthotopic xenograft (PDOX) nude-mouse model.
Adult pleomorphic rhabdomyosarcoma (RMS) is a rare and recalcitrant, highly-malignant mesenchymal tumor in need of improved therapeutic strategies. Our laboratory pioneered the patient-derived orthotopic xenograft (PDOX) nude mouse model with the technique of surgical orthotopic implantation (SOI). We previously described the development of a PDOX model of adult pleomorphic RMS where the tumor behaved similar to the patient donor. A high-grade pleomorphic rhabdomyosarcoma from a striated muscle was previously grown orthotopically in the right biceps-femoris muscle of nude mice to establish the PDOX model. In the present study, the PDOX models were randomized into the following treatment groups when tumor volume reached 100 mm3: G1, control without treatment; G2, cyclophosphamide (CPA) 140 mg/kg, intraperitoneal (i.p.) injection, weekly, for 3 weeks; G3, temozolomide (TEM), 25 mg/kg, per oral (p.o.), daily, for 21 days; G4, temozolomide (TEM) 25 mg/kg, p.o., daily, for 21 days combined with irinotecan (IRN), 4 mg/kg, i.p., daily for 21 days. After 3 weeks, treatment of PDOX with TEM combined with IRN was so powerful that it resulted in tumor regression and the smallest tumor volume compared to other groups. The RMS PDOX model should be of use to design the treatment program for the patient and for drug discovery and evaluation for this recalcitrant tumor type
Translocal imagination of Hong Kong connections: the shifting of Chow Yun-Fat's star image since 1997
Anyone who is interested in Hong Kong cinema must be familiar with one name: Chow Yun-fat (b. 1955). He rose to film stardom in the 1980s when Hong Kong cinema started to attract global attention beyond East Asia. During his early screen career, Chow established a star image as an urban citizen of modern Hong Kong through films such as A Better Tomorrow/Yingxiong bense (John Woo, 1986), City on Fire/Longhu fengyun (Ringo Lam, 1987), All About Ah-Long/A Lang de gushi (Johnnie To, 1989), God of Gamblers/Du shen (Wong Jing, 1989), and Hard Boiled/Lashou shentan (John Woo, 1992)
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