2,963 research outputs found
Cell survival in B16 melanoma after treatment with combinations of cytotoxic agents: lack of potentiation.
The extent of tumour, cell kill, produced by treating B16 melanomas with vincristine, cyclophosphamide, 5-fluorouracil and gamma-rays, alone and in combination, was determined using an in vitro colony assay. Cell kill by vincristine was revealed as a reduction in the yield of cells obtained by trypsinization, and as a decrease in the colony-forming ability of the extracted cells. The reduction in cell yield was interpreted as evidence of rapid cell lysis. Cyclophosphamide and gamma-rays also reduced both cell yield and surviving fraction, but in this case the small decrease in cell yield was due to an increase in cell volume. FU had no effect on cell yield, but surviving fraction was reduced. Tumour weight was also measured, and used in conjunction with cell yield and surviving fraction data to calculate the fraction of surviving cells per tumour following treatment with the agents. In combination studies, single doses of two different cytotoxic agents were given either simultaneously, or up to 24 h apart in either sequence, and assays were performed 24 h after the second drug was given. Combinations of vincristine + cyclophosphamide and 5-fluorouracil + gamma-rays were chosen because they had been shown by other workers to exhibit marked schedule dependency, including considerabl potentiation, against leukaemic cell lines. However, in the B16 melanoma there was no evidence of schedule-dependent cell killing with either of these combinations. For all sequences studied, the fraction of surviving cells per tumour was slightly greater than the predicted additive response calculated from single-drug controls
Association of Botryosphaeriaceae grapevine trunk disease fungi with the reproductive structures of Vitis vinifera
Several species belonging to the Botryosphaeriaceae were isolated from grapevine (Vitis vinifera) tissue other than wood during a survey of two vineyards planted to cultivars āChardonnayā and āShirazā in the Hunter Valley, New South Wales, Australia over the 2007/08 and 2008/09 growing seasons. A total of 188 isolates corresponding to nine different species of Diplodia, Dothiorella and Neofusicoccum anamorphs were isolated from dormant buds, flowers, pea-sized berries and mature berries prior to harvest in addition to 142 isolates from the trunks of the same vines. Furthermore, the occurrence of Dothiorella viticola, Diplodia mutila and Neofusicoccum australe is reported here for the first time from grapevines in the Hunter Valley. These findings may provide important information for the management and spread of Botryosphaeriaceae in vineyards where they are considered serious wood-invading pathogens. Botryosphaeriaceae are occasionally found on bunches, however, until now they have not directly been relatedĀ to bunch rots. Control strategies for trunk diseases caused by Botryosphaeriaceae are currently limited to remedial surgery and wound protection. These strategies do not consider other grapevine tissue as potential inoculum sources for infection of Botryosphaeriaceae in the vineyard.
Attacking Group Protocols by Refuting Incorrect Inductive Conjectures
Automated tools for finding attacks on flawed security protocols often fail to deal adequately with group protocols. This is because the abstractions made to improve performance on fixed 2 or 3 party protocols either preclude the modelling of group protocols all together, or permit modelling only in a fixed scenario, which can prevent attacks from being discovered. This paper describes Coral, a tool for finding counterexamples to incorrect inductive conjectures, which we have used to model protocols for both group key agreement and group key management, without any restrictions on the scenario. We will show how we used Coral to discover 6 previously unknown attacks on 3 group protocols
Classical and quantum regimes of two-dimensional turbulence in trapped Bose-Einstein condensates
We investigate two-dimensional turbulence in finite-temperature trapped
Bose-Einstein condensates within damped Gross-Pitaevskii theory. Turbulence is
produced via circular motion of a Gaussian potential barrier stirring the
condensate. We systematically explore a range of stirring parameters and
identify three regimes, characterized by the injection of distinct quantum
vortex structures into the condensate: (A) periodic vortex dipole injection,
(B) irregular injection of a mixture of vortex dipoles and co-rotating vortex
clusters, and (C) continuous injection of oblique solitons that decay into
vortex dipoles. Spectral analysis of the kinetic energy associated with
vortices reveals that regime (B) can intermittently exhibit a Kolmogorov
power law over almost a decade of length or wavenumber () scales.
The kinetic energy spectrum of regime (C) exhibits a clear power law
associated with an inertial range for weak-wave turbulence, and a
power law for high wavenumbers. We thus identify distinct regimes of forcing
for generating either two-dimensional quantum turbulence or classical weak-wave
turbulence that may be realizable experimentally.Comment: 11 pages, 10 figures. Minor updates to text and figures 1, 2 and
Non-equilibrium dynamics: Studies of reflection of Bose-Einstein condensates
The study of the non-equilibrium dynamics in Bose-Einstein condensed gases
has been dominated by the zero-temperature, mean field Gross-Pitaevskii
formalism. Motivated by recent experiments on the reflection of condensates
from silicon surfaces, we revisit the so-called {\em classical field}
description of condensate dynamics, which incorporates the effects of quantum
noise and can also be generalized to include thermal effects. The noise is
included in a stochastic manner through the initial conditions. We show that
the inclusion of such noise is important in the quantitative description of the
recent reflection experiments
Coherent spin control by electromagnetic vacuum fluctuations
In coherent control, electromagnetic vacuum fluctuations usually cause
coherence loss through irreversible spontaneous emission. However, since the
dissipation via emission is essentially due to correlation of the fluctuations,
when emission ends in a superposition of multiple final states, correlation
between different pathways may build up if the "which-way" information is not
fully resolved (i.e., the emission spectrum is broader than the transition
energy range). Such correlation can be exploited for spin-flip control in a
-type three-level system, which manifests itself as an all-optical
spin echo in nonlinear optics with two orders of optical fields saved as
compared with stimulated Raman processes. This finding represents a new class
of optical nonlinearity induced by electromagnetic vacuum fluctuations.Comment: 7 pages including 5 figure
Generic Model Refactorings
Many modeling languages share some common concepts and principles. For example, Java, MOF, and UML share some aspects of the concepts\ud
of classes, methods, attributes, and inheritance. However, model\ud
transformations such as refactorings specified for a given language\ud
cannot be readily reused for another language because their related\ud
metamodels may be structurally different. Our aim is to enable a\ud
flexible reuse of model transformations across various metamodels.\ud
Thus, in this paper, we present an approach allowing the specification\ud
of generic model transformations, in particular refactorings, so\ud
that they can be applied to different metamodels. Our approach relies\ud
on two mechanisms: (1) an adaptation based mainly on the weaving\ud
of aspects; (2) the notion of model typing, an extension of object\ud
typing in the model-oriented context. We validated our approach by\ud
performing some experiments that consisted of specifying three well\ud
known refactorings (Encapsulate Field, Move Method, and Pull Up Method)\ud
and applying each of them onto three different metamodels (Java,\ud
MOF, and UML)
The Josephson plasmon as a Bogoliubov quasiparticle
We study the Josephson effect in alkali atomic gases within the two-mode
approximation and show that there is a correspondence between the Bogoliubov
description and the harmonic limit of the phase representation. We demonstrate
that the quanta of the Josephson plasmon can be identified with the Bogoliubov
excitations of the two-site Bose fluid. We thus establish a mapping between the
Bogoliubov approximation for the many-body theory and the linearized pendulum
Hamiltonian.Comment: 9 pages, LaTeX, submitted to J. Phys.
Quantum state of two trapped Bose-Einstein condensates with a Josephson coupling
We consider the precise quantum state of two trapped, coupled Bose Einstein
condensates in the two-mode approximation. We seek a representation of the
state in terms of a Wigner-like distribution on the two-mode Bloch sphere. The
problem is solved using a self-consistent rotation of the unknown state to the
south pole of the sphere. The two-mode Hamiltonian is projected onto the
harmonic oscillator phase plane, where it can be solved by standard techniques.
Our results show how the number of atoms in each trap and the squeezing in the
number difference depend on the physical parameters. Considering negative
scattering lengths, we show that there is a regime of squeezing in the relative
phase of the condensates which occurs for weaker interactions than the
superposition states found by Cirac et al% (quant-ph/9706034, 13 June 1997).
The phase squeezing is also apparent in mildly asymmetric trap configurations.Comment: 26 pages, 11 figure
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