1,474 research outputs found
The reconstruction theorem in Besov spaces
The theory of regularity structures [9] sets up an abstract framework of modelled distributions generalising the usual Hölder functions and allowing one to give a meaning to several ill-posed stochastic PDEs. A key result in that theory is the so-called reconstruction theorem: it defines a continuous linear operator that maps spaces of modelled distributions into the usual space of distributions. In the present paper, we extend the scope of this theorem to analogues to the whole class of Besov spaces Bp,qγ with non-integer regularity indices. We then show that these spaces behave very much like their classical counterparts by obtaining the corresponding embedding theorems and Schauder-type estimates
SiNx:Tb3+--Yb3+, an efficient down-conversion layer compatible with a silicon solar cell process
SiN x : Tb 3+-Yb 3+, an efficient down-conversion layer compatible with
silicon solar cell process Abstract Tb 3+-Yb 3+ co-doped SiN x down-conversion
layers compatible with silicon Photovoltaic Technology were prepared by
reactive magnetron co-sputtering. Efficient sensitization of Tb 3+ ions through
a SiN x host matrix and cooperative energy transfer between Tb 3+ and Yb 3+
ions were evidenced as driving mechanisms of the down-conversion process. In
this paper, the film composition and microstructure are investigated alongside
their optical properties, with the aim of maximizing the rare earth ions
incorporation and emission efficiency. An optimized layer achieving the highest
Yb 3+ emission intensity was obtained by reactive magnetron co-sputtering in a
nitride rich atmosphere for 1.2 W/cm and 0.15 W/cm power density
applied on the Tb and Yb targets, respectively. It was determined that
depositing at 200 {\textdegree}C and annealing at 850 {\textdegree}C leads to
comparable Yb 3+ emission intensity than depositing at 500 {\textdegree}C and
annealing at 600 {\textdegree}C, which is promising for applications toward
silicon solar cells.Comment: Solar Energy Materials and Solar Cells, Elsevier, 201
Photometric Constraints on the Redshift of z~10 candidate UDFj-39546284 from deeper WFC3/IR+ACS+IRAC observations over the HUDF
Ultra-deep WFC3/IR observations on the HUDF from the HUDF09 program revealed
just one plausible z~10 candidate UDFj-39546284. UDFj-39546284 had all the
properties expected of a galaxy at z~10 showing (1) no detection in the deep
ACS+WFC3 imaging data blueward of the F160W band, exhibiting (2) a blue
spectral slope redward of the break, and showing (3) no prominent detection in
deep IRAC observations. The new, similarly deep WFC3/IR HUDF12 F160W
observations over the HUDF09/XDF allow us to further assess this candidate.
These observations show that this candidate, previously only detected at ~5.9
sigma in a single band, clearly corresponds to a real source. It is detected at
~5.3 sigma in the new H-band data and at ~7.8 sigma in the full 85-orbit H-band
stack. Interestingly, the non-detection of the source (<1 sigma) in the new
F140W observations suggests a higher redshift. Formally, the best-fit redshift
of the source utilizing all the WFC3+ACS (and IRAC+K-band) observations is
11.8+/-0.3. However, we consider the z~12 interpretation somewhat unlikely,
since the source would either need to be ~20x more luminous than expected or
show very high-EW Ly-alpha emission (which seems improbable given the extensive
neutral gas prevalent early in the reionization epoch). Lower-redshift
solutions fail if only continuum models are allowed. Plausible lower-redshift
solutions require that the H-band flux be dominated by line emission such as
Halpha or [OIII] with extreme EWs. The tentative detection of line emission at
1.6 microns in UDFj-39546284 in a companion paper suggests that such emission
may have already been found.Comment: 6 pages, 4 figures, 1 table, accepted for publication in ApJ Letters,
updated to match the version in pres
S-CANDELS: The Spitzer-Cosmic Assembly Near-Infrared Deep Extragalactic Survey. Survey Design, Photometry, and Deep IRAC Source Counts
The Spitzer-Cosmic Assembly Deep Near-Infrared Extragalactic Legacy Survey
(S-CANDELS; PI G. Fazio) is a Cycle 8 Exploration Program designed to detect
galaxies at very high redshifts (z > 5). To mitigate the effects of cosmic
variance and also to take advantage of deep coextensive coverage in multiple
bands by the Hubble Space Telescope Multi-Cycle Treasury Program CANDELS,
S-CANDELS was carried out within five widely separated extragalactic fields:
the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS,
the HST Deep Field North, and the Extended Groth Strip. S-CANDELS builds upon
the existing coverage of these fields from the Spitzer Extended Deep Survey
(SEDS) by increasing the integration time from 12 hours to a total of 50 hours
but within a smaller area, 0.16 square degrees. The additional depth
significantly increases the survey completeness at faint magnitudes. This paper
describes the S-CANDELS survey design, processing, and publicly-available data
products. We present IRAC dual-band 3.6+4.5 micron catalogs reaching to a depth
of 26.5 AB mag. Deep IRAC counts for the roughly 135,000 galaxies detected by
S-CANDELS are consistent with models based on known galaxy populations. The
increase in depth beyond earlier Spitzer/IRAC surveys does not reveal a
significant additional contribution from discrete sources to the diffuse Cosmic
Infrared Background (CIB). Thus it remains true that only roughly half of the
estimated CIB flux from COBE/DIRBE is resolved.Comment: 23 pages, 19 figures, accepted by ApJ
Positive Impact of Increases in Condom Use among Female Sex Workers and Clients in a Medium HIV Prevalence Epidemic: Modelling Results from Project SIDA1/2/3 in Cotonou, Benin
Background A comprehensive, HIV prevention programme (Projet Sida1/2/3) was implemented among female sex workers (FSWs) in Cotonou, Benin, in 1993 following which condom use among FSWs increased threefold between 1993 and 2008 while FSW HIV prevalence declined from 53.3% to 30.4%. Objective Estimate the potential impact of the intervention on HIV prevalence/incidence in FSWs, clients and the general population in Cotonou, Benin. Methods and Findings A transmission dynamics model parameterised with setting-specific bio-behavioural data was used within a Bayesian framework to fit the model and simulate HIV transmission in the high and low-risk population of Cotonou and to estimate HIV incidence and infections averted by SIDA1/2/3. Our model results suggest that prior to SIDA1/2/3 commercial sex had contributed directly or indirectly to 93% (84–98%) of all cumulative infections and that the observed decline in FSWs HIV prevalence was more consistent with the self-reported post-intervention increase in condom use by FSWs than a counterfactual assuming no change in condom use after 1993 (CF-1). Compared to the counterfactual (CF-1), the increase in condom use may have prevented 62% (52–71%) of new HIV infections among FSWs between 1993 and 2008 and 33% (20–46%) in the overall population. Conclusions Our analysis provides plausible evidence that the post-intervention increase in condom use during commercial sex significantly reduced HIV prevalence and incidence among FSWs and general population. Sex worker interventions can be effective even in medium HIV prevalence epidemics and need to be sustained over the long-term
- …