19,038 research outputs found
Cross-section and polarization of neutrino-produced 's made simple
Practical formulae are derived for the cross-section and polarization of the
lepton produced in deep-inelastic neutrino-nucleon scattering in the
frame of the simple quark-parton model.Comment: 10 pages, no figure
Self-management of context-aware overlay ambient networks
Ambient Networks (ANs) are dynamically changing and heterogeneous as they consist of potentially large numbers of independent, heterogeneous mobile nodes, with spontaneous topologies that can logically interact with each other to share a common control space, known as the Ambient Control Space. ANs are also flexible i.e. they can compose and decompose dynamically and automatically, for supporting the deployment of cross-domain (new) services. Thus, the AN architecture must be sophisticatedly designed to support such high level of dynamicity, heterogeneity and flexibility. We advocate the use of service specific overlay networks in ANs, that are created on-demand according to specific service requirements, to deliver, and to automatically adapt services to the dynamically changing user and network context. This paper presents a self-management approach to create, configure, adapt, contextualise, and finally teardown service specific overlay networks
Modelling the dynamics of turbulent floods
Consider the dynamics of turbulent flow in rivers, estuaries and floods. Based on the widely used k-epsilon model for turbulence, we use the techniques of centre manifold theory to derive dynamical models for the evolution of the water depth and of vertically averaged flow velocity and turbulent parameters. This new model for the shallow water dynamics of turbulent flow: resolves the vertical structure of the flow and the turbulence; includes interaction between turbulence and long waves; and gives a rational alternative to classical models for turbulent environmental flows
Variable-Frequency QPOs from the Galactic Microquasar GRS 1915+105
We show that the galactic microquasar GRS 1915+105 exhibits quasi-periodic
oscillations (QPOs) whose frequency varies continuously from 1-15 Hz, during
spectrally hard dips when the source is in a flaring state. We report here
analyses of simultaneous energy spectra and power density spectra at 4 s
intervals. The energy spectrum is well fit at each time step by an optically
thick accretion disk plus power law model, while the power density spectrum
consists of a varying red noise component plus the variable frequency QPO. The
features of both spectra are strongly correlated with one another. The 1-15 Hz
QPOs appear when the power law component becomes hard and intense, and
themselves have an energy spectrum consistent with the power law component
(with root mean square amplitudes as high as 10%). The frequency of the
oscillations, however, is most strikingly correlated with the parameters of the
thermal disk component. The tightest correlation is between QPO frequency and
the disk X-ray flux. This fact indicates that the properties of the QPO are not
determined by solely a disk or solely a corona.Comment: Accepted to ApJ Letters, 12 pages, 3 figures, AASTEX forma
Affine Subspace Representation for Feature Description
This paper proposes a novel Affine Subspace Representation (ASR) descriptor
to deal with affine distortions induced by viewpoint changes. Unlike the
traditional local descriptors such as SIFT, ASR inherently encodes local
information of multi-view patches, making it robust to affine distortions while
maintaining a high discriminative ability. To this end, PCA is used to
represent affine-warped patches as PCA-patch vectors for its compactness and
efficiency. Then according to the subspace assumption, which implies that the
PCA-patch vectors of various affine-warped patches of the same keypoint can be
represented by a low-dimensional linear subspace, the ASR descriptor is
obtained by using a simple subspace-to-point mapping. Such a linear subspace
representation could accurately capture the underlying information of a
keypoint (local structure) under multiple views without sacrificing its
distinctiveness. To accelerate the computation of ASR descriptor, a fast
approximate algorithm is proposed by moving the most computational part (ie,
warp patch under various affine transformations) to an offline training stage.
Experimental results show that ASR is not only better than the state-of-the-art
descriptors under various image transformations, but also performs well without
a dedicated affine invariant detector when dealing with viewpoint changes.Comment: To Appear in the 2014 European Conference on Computer Visio
Antitumorigenic Evaluation of Thalidomide Alone and in Combination with Cisplatin in DBA2/J Mice
Thalidomide's reported ability to inhibit angiogenesis has led to clinical trials determining its effectiveness in combating various types of cancer. This study explored thalidomide's antitumorigenic potential when administered alone and in combination with cisplatin to DBA2/J mice whose tumors were induced by murine erythroleukemic cells. Thalidomide treatment alone produced no significant inhibitory effect on tumor development and metastasis. Mice that received both drugs had significantly lower incidences of both primary and secondary tumors as compared to the untreated control group. Cisplatin, administered alone or in combination with thalidomide, led to a significant delay in tumor formation and a longer life span than was recorded in untreated mice. However, the combination treatment results were not significantly different from those of cisplatin treatment used as a single agent. In in vitro cell multiplication studies using murine erythroleukemic and murine endothelial cells, thalidomide failed to inhibit cell proliferation. However, cisplatin treatment with or without thalidomide, significantly inhibited the multiplication of both cell lines in a dose dependent manner. Thalidomide does not appear to be a beneficial adjuvant to cisplatin treatment
Clarification of the relationship between bound and scattering states in quantum mechanics: Application to 12C + alpha
Using phase-equivalent supersymmetric partner potentials, a general result
from the inverse problem in quantum scattering theory is illustrated, i.e.,
that bound-state properties cannot be extracted from the phase shifts of a
single partial wave, as a matter of principle. In particular, recent R-matrix
analyses of the 12C + alpha system, extracting the asymptotic normalization
constant of the 2+ subthreshold state, C12, from the l=2 elastic-scattering
phase shifts and bound-state energy, are shown to be unreliable. In contrast,
this important constant in nuclear astrophysics can be deduced from the
simultaneous analysis of the l=0, 2, 4, 6 partial waves in a simplified
potential model. A new supersymmetric inversion potential and existing models
give C12=144500+-8500 fm-1/2.Comment: Expanded version (50% larger); three errors corrected (conversion of
published reduced widths to ANCs); nine references added, one remove
Recommended from our members
The first international workshop on the role and impact of mathematics in medicine: a collective account
The First International Workshop on The Role and Impact of Mathematics in Medicine (RIMM) convened in Paris in June 2010. A broad range of researchers discussed the difficulties, challenges and opportunities faced by
those wishing to see mathematical methods contribute to improved medical outcomes. Finding mechanisms for inter-
disciplinary meetings, developing a common language, staying focused on the medical problem at hand, deriving
realistic mathematical solutions, obtainin
Second year technical report on-board processing for future satellite communications systems
Advanced baseband and microwave switching techniques for large domestic communications satellites operating in the 30/20 GHz frequency bands are discussed. The nominal baseband processor throughput is one million packets per second (1.6 Gb/s) from one thousand T1 carrier rate customer premises terminals. A frequency reuse factor of sixteen is assumed by using 16 spot antenna beams with the same 100 MHz bandwidth per beam and a modulation with a one b/s per Hz bandwidth efficiency. Eight of the beams are fixed on major metropolitan areas and eight are scanning beams which periodically cover the remainder of the U.S. under dynamic control. User signals are regenerated (demodulated/remodulated) and message packages are reformatted on board. Frequency division multiple access and time division multiplex are employed on the uplinks and downlinks, respectively, for terminals within the coverage area and dwell interval of a scanning beam. Link establishment and packet routing protocols are defined. Also described is a detailed design of a separate 100 x 100 microwave switch capable of handling nonregenerated signals occupying the remaining 2.4 GHz bandwidth with 60 dB of isolation, at an estimated weight and power consumption of approximately 400 kg and 100 W, respectively
Roughness of Interfacial Crack Front: Correlated Percolation in the Damage Zone
We show that the roughness exponent zeta of an in-plane crack front slowly
propagating along a heterogeneous interface embeded in a elastic body, is in
full agreement with a correlated percolation problem in a linear gradient. We
obtain zeta=nu/(1+nu) where nu is the correlation length critical exponent. We
develop an elastic brittle model based on both the 3D Green function in an
elastic half-space and a discrete interface of brittle fibers and find
numerically that nu=1.5, We conjecture it to be 3/2. This yields zeta=3/5. We
also obtain by direct numerical simulations zeta=0.6 in excellent agreement
with our prediction. This modelling is for the first time in close agreement
with experimental observations.Comment: 4 pages RevTeX
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