972 research outputs found
Vertex Intrinsic Fitness: How to Produce Arbitrary Scale-Free Networks
We study a recent model of random networks based on the presence of an
intrinsic character of the vertices called fitness. The vertices fitnesses are
drawn from a given probability distribution density. The edges between pair of
vertices are drawn according to a linking probability function depending on the
fitnesses of the two vertices involved. We study here different choices for the
probability distribution densities and the linking functions. We find that,
irrespective of the particular choices, the generation of scale-free networks
is straightforward. We then derive the general conditions under which
scale-free behavior appears. This model could then represent a possible
explanation for the ubiquity and robustness of such structures.Comment: 4 pages, 3 figures, RevTe
Overview of progress in neutrino scattering measurements
Recent progress in neutrino scattering experiments with few GeV neutrino
beams is reviewed, focusing on new experimental input since the beginning of
the NuInt workshop series in 2001. Progress in neutrino quasi-elastic
scattering, resonance production, coherent pion production, scattering in the
transition region between the resonance and deep inelastic regimes, and nuclear
effects in neutrino-nucleus scattering, is discussed.Comment: To appear in the proceedings of 5th International Workshop on
Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt07), Batavia,
Illinois, 30 May - 3 Jun 2007. Submitted to AIP Conf.Pro
Can a 3+2 Oscillation Model Explain the NuTeV Electroweak Results?
The weak mixing angle result from NuTeV falls three standard deviations above
the value determined by global electroweak fits. It has been suggested that one
possible explanation for this result could be the oscillation of electron
neutrinos in the NuTeV beam to sterile neutrinos. This article examines several
cases of masses and mixings for 3+2 neutrino oscillation models which fit the
current oscillation data at 99% CL. We conclude that electron to sterile
neutrino oscillations can account for only up to a third of a standard
deviation between the NuTeV determination of the weak mixing angle and the
standard model.Comment: 3 pages, 2 figures, submitted to Brief Report
Exploring multi-stability in semiconductor ring lasers: theory and experiment
We report the first experimental observation of multi-stable states in a
single-longitudinal mode semiconductor ring laser. We show how the operation of
the device can be steered to either monostable, bistable or multi-stable
dynamical regimes in a controlled way. We observe that the dynamical regimes
are organized in well reproducible sequences that match the bifurcation
diagrams of a two-dimensional model. By analyzing the phase space in this
model, we predict how the stochastic transitions between multi-stable states
take place and confirm it experimentally.Comment: 4 pages, 5 figure
Topological insight into the non-Arrhenius mode hopping of semiconductor ring lasers
We investigate both theoretically and experimentally the stochastic switching
between two counter-propagating lasing modes of a semiconductor ring laser.
Experimentally, the residence time distribution cannot be described by a simple
one parameter Arrhenius exponential law and reveals the presence of two
different mode-hop scenarios with distinct time scales. In order to elucidate
the origin of these two time scales, we propose a topological approach based on
a two-dimensional dynamical system.Comment: 4 pages, 3 figure
Neutrino interactions with nuclei
We present a model for neutrino-nucleus scattering in the energy region
relevant for present and forthcoming neutrino-oscillation experiments. The
model is based on the RPA treatment of the nuclear responses in the
quasi-elastic and Delta-resonance region. It includes also in a
phenomenological way nucleon knock-out. It aims at the description, within a
single framework, of several final state channels i.e. quasi-elastic,
incoherent and coherent one-pion production and two- or several-nucleon
knock-out.Comment: To appear in the proceedings of 6th International Workshop on
Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt09), Sitges, Spain,
18 - 22 May 200
MiniBooNE
The physics motivations, design, and status of the Booster Neutrino
Experiment at Fermilab, MiniBooNE, are briefly discussed. Particular emphasis
is given on the ongoing preparatory work that is needed for the MiniBooNE muon
neutrino to electron neutrino oscillation appearance search. This search aims
to confirm or refute in a definitive and independent way the evidence for
neutrino oscillations reported by the LSND experiment.Comment: 3 pages, no figures, to appear in the proceedings of the 9th
International Conference on Astroparticle and Underground Physics (TAUP
2005), Zaragoza, Spain, 10-14 Sep 200
Investigation of mid-infrared AlInSb LEDs with an n-i-p structure
We report on the investigation on mid-infrared AlInSb LEDs with an n-i-p structure. Compared to the conventional AlInSb LEDs with a p-i-n structure, a better current spreading corresponding to a uniform current distribution in the active region is expected in the n-i-p structure because of a high electron mobility in the n-type AlInSb material. The output optical power of laterally injected LEDs were investigated as a function of the device geometry by COMSOL simulations and confirmed by experimental results
The Critical Role of Genome Maintenance Proteins in Immune Evasion During Gammaherpesvirus Latency
Gammaherpesviruses are important pathogens that establish latent infection in their natural host for lifelong persistence. During latency, the viral genome persists in the nucleus of infected cells as a circular episomal element while the viral gene expression program is restricted to non-coding RNAs and a few latency proteins. Among these, the genome maintenance protein (GMP) is part of the small subset of genes expressed in latently infected cells. Despite sharing little peptidic sequence similarity, gammaherpesvirus GMPs have conserved functions playing essential roles in latent infection. Among these functions, GMPs have acquired an intriguing capacity to evade the cytotoxic T cell response through self-limitation of MHC class I-restricted antigen presentation, further ensuring virus persistence in the infected host. In this review, we provide an updated overview of the main functions of gammaherpesvirus GMPs during latency with an emphasis on their immune evasion properties
Ultrashort Q-switched pulses from a passively mode-locked distributed Bragg reflector semiconductor laser
A compact semiconductor mode-locked laser (MLL) is presented that demonstrates strong passive Q-switched mode-locking over a wide range of drive conditions. The Q-switched frequency is tunable between 1 and 4Â GHz for mode-locked pulses widths around 3.5Â ps. The maximum ratio of peak to average power of the pulse-train is >120, greatly exceeding that of similarly sized passively MLLs
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