888,937 research outputs found
First excited state calculation using different phonon bases for the two-site Holstein model
The single-electron energy and static charge-lattice deformation correlations
have been calculated for the first excited state of a two-site Holstein model
within perturbative expansions using different standard phonon bases obtained
through Lang-Firsov (LF) transformation, LF with squeezed phonon states,
modified LF, modified LF transformation with squeezed phonon states, and also
within weak-coupling perturbation approach. Comparisons of the convergence of
the perturbative expansions for different phonon bases reveal that modified LF
approach works much better than other approaches for major range of the
coupling strength.Comment: 11 pages (REVTEX), 4 postscript figure
Representing Isabelle in LF
LF has been designed and successfully used as a meta-logical framework to
represent and reason about object logics. Here we design a representation of
the Isabelle logical framework in LF using the recently introduced module
system for LF. The major novelty of our approach is that we can naturally
represent the advanced Isabelle features of type classes and locales.
Our representation of type classes relies on a feature so far lacking in the
LF module system: morphism variables and abstraction over them. While
conservative over the present system in terms of expressivity, this feature is
needed for a representation of type classes that preserves the modular
structure. Therefore, we also design the necessary extension of the LF module
system.Comment: In Proceedings LFMTP 2010, arXiv:1009.218
Cessation of mass drug administration for lymphatic filariasis in Zanzibar in 2006: was transmission interrupted?
BACKGROUND: Lymphatic filariasis (LF) is targeted for elimination through annual mass drug administration (MDA) for 4-6 years. In 2006, Zanzibar stopped MDA against LF after five rounds of MDA revealed no microfilaraemic individuals during surveys at selected sentinel sites. We asked the question if LF transmission was truly interrupted in 2006 when MDA was stopped. METHODOLOGY/PRINCIPAL FINDINGS: In line with ongoing efforts to shrink the LF map, we performed the WHO recommended transmission assessment surveys (TAS) in January 2012 to verify the absence of LF transmission on the main Zanzibar islands of Unguja and Pemba. Altogether, 3275 children were tested on both islands and 89 were found to be CFA positive; 70 in Pemba and 19 in Unguja. The distribution of schools with positive children was heterogeneous with pronounced spatial variation on both islands. Based on the calculated TAS cut-offs of 18 and 20 CFA positive children for Pemba and Unguja respectively, we demonstrated that transmission was still ongoing in Pemba where the cut-off was exceeded. CONCLUSIONS: Our findings indicated ongoing transmission of LF on Pemba in 2012. Moreover, we presented evidence from previous studies that LF transmission was also active on Unguja shortly after stopping MDA in 2006. Based on these observations the government of Zanzibar decided to resume MDA against LF on both islands in 2013
Light Field Denoising via Anisotropic Parallax Analysis in a CNN Framework
Light field (LF) cameras provide perspective information of scenes by taking
directional measurements of the focusing light rays. The raw outputs are
usually dark with additive camera noise, which impedes subsequent processing
and applications. We propose a novel LF denoising framework based on
anisotropic parallax analysis (APA). Two convolutional neural networks are
jointly designed for the task: first, the structural parallax synthesis network
predicts the parallax details for the entire LF based on a set of anisotropic
parallax features. These novel features can efficiently capture the high
frequency perspective components of a LF from noisy observations. Second, the
view-dependent detail compensation network restores non-Lambertian variation to
each LF view by involving view-specific spatial energies. Extensive experiments
show that the proposed APA LF denoiser provides a much better denoising
performance than state-of-the-art methods in terms of visual quality and in
preservation of parallax details
Deep near-infrared luminosity function of a cluster of galaxies at z=0.3
The deep near-infrared luminosity function of AC118, a cluster of galaxies at
z=0.3, is presented. AC118 is a bimodal cluster, as evidenced both by our
near-infrared images of lensed galaxies, by public X-ray Rosat images and by
the spatial distribution of bright galaxies. Taking advantage of the extension
and depth of our data, which sample an almost unexplored region in the depth
vs. observed area diagram, we derive the luminosity function (LF), down to the
dwarf regime (M*+5), computed in several cluster portions. The overall LF,
computed on a 2.66 Mpc2 areas (H_0=50 km/s/Mpc), has an intermediate slope
(alpha=-1.2). However, the LF parameters depend on the surveyed cluster region:
the central concentration has 2.6^{+5.1}_{-1.7} times more bright galaxies and
5.3^{+7.2}_{-2.3} times less dwarfs per typical galaxy than the outer region,
which includes galaxies at an average projected distance of ~580 kpc (errors
are quoted at the 99.9 % confidence level). The LF in the secondary AC118 clump
is intermediate between the central and outer one. In other words, the
near-infrared AC118 LF steepens going from high to low density regions. At an
average clustercentric distance of ~580 kpc, the AC118 LF is statistically
indistinguishable from the LF of field galaxies at similar redshift, thus
suggesting that the hostile cluster environment plays a minor role in shaping
the LF at large clustercentric distances, while it strongly affects the LF at
higher galaxy density.Comment: ApJ, in press. The whole paper with all high resolution images is
available at http://www.na.astro.it/~andreon/listapub.htm
The ISO 170um Luminosity Function of Galaxies
We constructed a local luminosity function (LF) of galaxies using a
flux-limited sample (S_170 > 0.195Jy) of 55 galaxies at z < 0.3 taken from the
ISO FIRBACK survey at 170um. The overall shape of the 170-um LF is found to be
different from that of the total 60-um LF (Takeuchi et al. 2003): the bright
end of the LF declines more steeply than that of the 60-um LF. This behavior is
quantitatively similar to the LF of the cool subsample of the IRAS PSCz
galaxies. We also estimated the strength of the evolution of the LF by assuming
the pure luminosity evolution (PLE): L(z) \propto (1+z)^Q. We obtained
Q=5.0^{+2.5}_{-0.5} which is similar to the value obtained by recent Spitzer
observations, in spite of the limited sample size. Then, integrating over the
170-um LF, we obtained the local luminosity density at 170um, \rho_L(170um). A
direct integration of the LF gives \rho_L(170um) = 1.1 \times 10^8 h Lsun
Mpc^{-3}, whilst if we assume a strong PLE with Q=5, the value is 5.2 \times
10^7 h Lsun Mpc^{-3}. This is a considerable contribution to the local FIR
luminosity density. By summing up with other available infrared data, we
obtained the total dust luminosity density in the Local Universe,
\rho_L(dust)=1.1 \times 10^8 h Lsun Mpc^{-3}. Using this value, we estimated
the cosmic star formation rate (SFR) density hidden by dust in the Local
Universe. We obtained \rho_SFR(dust) \simeq 1.1-1.2 h \times 10^{-2} Msun
yr^{-1} Mpc^{-3}$, which means that 58.5% of the star formation is obscured by
dust in the Local Universe.Comment: A&A in pres
- …