359 research outputs found
Non-Hermitian SUSY Hydrogen-like Hamiltonians with real spectra
It is shown that the radial part of the Hydrogen Hamiltonian factorizes as
the product of two not mutually adjoint first order differential operators plus
a complex constant epsilon. The 1-susy approach is used to construct
non-hermitian Hamiltonians with hydrogen spectra. Other non-hermitian
Hamiltonians are shown to admit an extra `complex energy' at epsilon. New
self-adjoint hydrogen-like Hamiltonians are also derived by using a 2-susy
transformation with complex conjugate pairs epsilon, (c.c) epsilon.Comment: LaTeX2e file, 13 pages, 6 EPS figures. New references added. The
present is a reorganized and simplified versio
Activation of visible up-conversion luminescence in transparent and conducting ZnO:Er:Yb films by laser annealing
Transparent and conducting ZnO:Er:Yb thin films with visible up-conversion (660-nm emission under 980-nm excitation) were fabricated by RF magnetron sputtering. The as-deposited films were found to be transparent and conducting and the activation of the Er ions in these films to produce up-conversion luminescence was achieved by different post deposition annealing treatments in air, vacuum or by laser annealing using a Nd:YVO4 laser. The structural, electrical and optical properties and the up-conversion efficiency of these films were found to be strongly influenced by the annealing method, and a detailed study is reported in this paper. It has been demonstrated that, although the air annealing was the most efficient in terms of up-conversion, laser annealing was the only method capable of activating Er ions while preserving the electrical conductivity of the doped films. It has been shown that a minimum energy was needed in laser annealing to optically activate the rare earth ions in the ZnO host material to produce up-conversion. Up-converting and transparent conducting ZnO:Er:Yb films with an electrical resistivity of 5×10-2 Ω·cm and transparency ~80% in the visible wavelength range has been achieved by laser annealing
The alhambra survey: evolution of galaxy spectral segregation
We study the clustering of galaxies as a function of spectral type and redshift in the range 0.35 <z <1.1 using data from the Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The data cover 2.381 deg2 in 7 fields, after applying a detailed angular selection mask, with accurate photometric redshifts down to IAB <24. From this catalog we draw five fixed number density redshift-limited bins. We estimate the clustering evolution for two different spectral populations selected using the ALHAMBRA-based photometric templates: quiescent and star-forming galaxies. For each sample we measure the real-space clustering using the projected correlation function. Our calculations are performed over the range [0.03, 10.0] h-1 Mpc, allowing us to find a steeper trend for Mpc, which is especially clear for star-forming galaxies. Our analysis also shows a clear early differentiation in the clustering properties of both populations: star-forming galaxies show weaker clustering with evolution in the correlation length over the analyzed redshift range, while quiescent galaxies show stronger clustering already at high redshifts and no appreciable evolution. We also perform the bias calculation where similar segregation is found, but now it is among the quiescent galaxies where a growing evolution with redshift is clearer (abrigatted). These findings clearly corroborate the well-known color-density relation, confirming that quiescent galaxies are mainly located in dark matter halos that are more massive than those typically populated by star-forming galaxies.Ministerio de Economía y Competitividad y FEDER AYA2010-22111-C03-02 AYA2013-48623-C2-2 AYA2012-39620 AYA2013-40611-P AYA2013-42227-P AYA2013-43188-P AYA2013-48623-C2-1 ESP2013-48274 AYA2014-58861-C3-1Junta de Andalucía TIC114 JA2828 P10-FQM-644
Analysis and description of disease-specific quality of life in patients with anal fistula
INTRODUCTION:
In patients diagnosed with anal fistula, knowing the quality of life specifically related to the disease can help coloproctology specialists to choose the most appropriate therapeutic strategy for each case. The aim of our study is to analyzse and describe the factors related to the specific quality of life in a consecutive series of patients diagnosed with anal fistula.
METHODS:
Observational, cross-sectional study carried out from March 2015 to February 2017. All patients were assessed in the colorectal surgery unit of a hospital in southeast of Spain. After performing an initial anamnesis and a physical examination, patients diagnosed with anal fistula completed the Quality of Life in Ppatients with Anal Fistula Questionnaire (QoLAF-Q). This questionnaire specifically measures quality of life in people with anal fistula and its score range is the following: zero impact = 14 points, limited impact = 15 to 28 points, moderate impact = 29 to 42 points, high impact = 43 to 56 points, and very high impact = 57 to 70 points.
RESULTS:
A total of 80 patients were included. The median score obtained in the questionnaire for the sample studied was 34.00 (range=14-68). Statistically significant differences between patients with "primary anal fistula" (n=65) and "recurrent anal fistula" (n=15) were observed (mean rank=42.96 vs. mean rank=29.83, p=0.048). Furthermore, an inverse proportion (P=.016) between "time with clinical symptoms" and "impact on quality of life" was found (5 years: mean rank = 19.00). There were no statistically significant differences (P=.149) between quality of life amongst patients diagnosed with complex (mean rank = 36.13) and simple fistulae (mean rank = 43.59).
CONCLUSIONS:
Anal fistulae exert moderate-high impact on patients' quality of life. "Shorter time experiencing clinical symptoms" and the "presence of primary fistula" are factors that can be associated with worse quality of life
The ALHAMBRA survey: evolution of galaxy spectral segregation
We study the clustering of galaxies as a function of spectral type and
redshift in the range using data from the Advanced Large
Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The data
cover 2.381 deg in 7 fields, after applying a detailed angular selection
mask, with accurate photometric redshifts [] down to
. From this catalog we draw five fixed number density,
redshift-limited bins. We estimate the clustering evolution for two different
spectral populations selected using the ALHAMBRA-based photometric templates:
quiescent and star-forming galaxies. For each sample, we measure the real-space
clustering using the projected correlation function. Our calculations are
performed over the range Mpc, allowing us to find a
steeper trend for Mpc, which is especially clear for
star-forming galaxies. Our analysis also shows a clear early differentiation in
the clustering properties of both populations: star-forming galaxies show
weaker clustering with evolution in the correlation length over the analysed
redshift range, while quiescent galaxies show stronger clustering already at
high redshifts, and no appreciable evolution. We also perform the bias
calculation where similar segregation is found, but now it is among the
quiescent galaxies where a growing evolution with redshift is clearer. These
findings clearly corroborate the well known colour-density relation, confirming
that quiescent galaxies are mainly located in dark matter halos that are more
massive than those typically populated by star-forming galaxies.Comment: 14 pages, 9 figures, accepted by Ap
The ALHAMBRA survey : Estimation of the clustering signal encoded in the cosmic variance
The relative cosmic variance () is a fundamental source of
uncertainty in pencil-beam surveys and, as a particular case of count-in-cell
statistics, can be used to estimate the bias between galaxies and their
underlying dark-matter distribution. Our goal is to test the significance of
the clustering information encoded in the measured in the ALHAMBRA
survey. We measure the cosmic variance of several galaxy populations selected
with band luminosity at as the intrinsic dispersion in
the number density distribution derived from the 48 ALHAMBRA subfields. We
compare the observational with the cosmic variance of the dark
matter expected from the theory, . This provides an
estimation of the galaxy bias . The galaxy bias from the cosmic variance is
in excellent agreement with the bias estimated by two-point correlation
function analysis in ALHAMBRA. This holds for different redshift bins, for red
and blue subsamples, and for several band luminosity selections. We find
that increases with the band luminosity and the redshift, as expected
from previous work. Moreover, red galaxies have a larger bias than blue
galaxies, with a relative bias of . Our results
demonstrate that the cosmic variance measured in ALHAMBRA is due to the
clustering of galaxies and can be used to characterise the affecting
pencil-beam surveys. In addition, it can also be used to estimate the galaxy
bias from a method independent of correlation functions.Comment: Astronomy and Astrophysics, in press. 9 pages, 4 figures, 3 table
Stellar populations of galaxies in the ALHAMBRA survey up to . II. Stellar content of quiescent galaxies within the dust-corrected stellar masscolour and the colourcolour diagrams
Our aim is to determine the distribution of stellar population parameters
(extinction, age, metallicity, and star formation rate) of quiescent galaxies
within the rest-frame stellar masscolour and colourcolour diagrams
corrected for extinction up to . These novel diagrams reduce the
contamination in samples of quiescent galaxies owing to dust-reddened galaxies,
and they provide useful constraints on stellar population parameters. We set
constraints on the stellar population parameters of quiescent galaxies
combining the ALHAMBRA multi-filter photo-spectra with our SED-fitting code
MUFFIT, making use of composite stellar population models. The extinction
obtained by MUFFIT allowed us to remove dusty star-forming (DSF) galaxies from
the sample of red galaxies. The distributions of stellar population
parameters across these rest-frame diagrams are revealed after the dust
correction and are fitted by the LOESS method to reduce uncertainty effects.
Quiescent galaxy samples defined via classical diagrams are typically
contaminated by a % fraction of DSF galaxies. A significant part of the
galaxies in the green valley are actually obscured star-forming galaxies
(%). Consequently, the transition of galaxies from the blue cloud to
the red sequence, and hence the related mechanisms for quenching, seems to be
much more efficient and faster than previously reported. The rest-frame stellar
masscolour and colourcolour diagrams are useful for constraining
the age, metallicity, extinction, and star formation rate of quiescent galaxies
by only their redshift, rest-frame colours, and/or stellar mass. Dust
correction plays an important role in understanding how quiescent galaxies are
distributed in these diagrams and is key to performing a pure selection of
quiescent galaxies via intrinsic colours.Comment: (37 pages, 29 figures, accepted for publication in A&A
The ALHAMBRA survey: Accurate merger fractions by PDF analysis of photometric close pairs
Our goal is to develop and test a novel methodology to compute accurate close
pair fractions with photometric redshifts. We improve the current methodologies
to estimate the merger fraction f_m from photometric redshifts by (i) using the
full probability distribution functions (PDFs) of the sources in redshift
space, (ii) including the variation in the luminosity of the sources with z in
both the selection of the samples and in the luminosity ratio constrain, and
(iii) splitting individual PDFs into red and blue spectral templates to deal
robustly with colour selections. We test the performance of our new methodology
with the PDFs provided by the ALHAMBRA photometric survey. The merger fractions
and rates from the ALHAMBRA survey are in excellent agreement with those from
spectroscopic work, both for the general population and for red and blue
galaxies. With the merger rate of bright (M_B <= -20 - 1.1z) galaxies evolving
as (1+z)^n, the power-law index n is larger for blue galaxies (n = 2.7 +- 0.5)
than for red galaxies (n = 1.3 +- 0.4), confirming previous results.
Integrating the merger rate over cosmic time, we find that the average number
of mergers per galaxy since z = 1 is N_m = 0.57 +- 0.05 for red galaxies and
N_m = 0.26 +- 0.02 for blue galaxies. Our new methodology exploits
statistically all the available information provided by photometric redshift
codes and provides accurate measurements of the merger fraction by close pairs
only using photometric redshifts. Current and future photometric surveys will
benefit of this new methodology.Comment: Submitted to A&A, 15 pages, 15 figures, 6 tables. Comments are
welcome. Close pair systems available at
https://cloud.iaa.csic.es/alhambra/catalogues/ClosePairs
The supersymmetric modified Poschl-Teller and delta-well potentials
New supersymmetric partners of the modified Poschl-Teller and the Dirac's
delta well potentials are constructed in closed form. The resulting
one-parametric potentials are shown to be interrelated by a limiting process.
The range of values of the parameters for which these potentials are free of
singularities is exactly determined. The construction of higher order
supersymmetric partner potentials is also investigated.Comment: 20 pages, LaTeX file, 4 eps figure
The ALHAMBRA photometric system
This paper presents the characterization of the optical range of the ALHAMBRA
photometric system, a 20 contiguous, equal-width, medium-band CCD system with
wavelength coverage from 3500A to 9700A. The photometric description of the
system is done by presenting the full response curve as a product of the
filters, CCD and atmospheric transmission curves, and using some first and
second order moments of this response function. We also introduce the set of
standard stars that defines the system, formed by 31 classic spectrophotometric
standard stars which have been used in the calibration of other known
photometric systems, and 288 stars, flux calibrated homogeneously, from the
Next Generation Spectral Library (NGSL). Based on the NGSL, we determine the
transformation equations between Sloan Digital Sky Survey (SDSS) ugriz
photometry and the ALHAMBRA photometric system, in order to establish some
relations between both systems. Finally we develop and discuss a strategy to
calculate the photometric zero points of the different pointings in the
ALHAMBRA project.Comment: Astronomical Journal on the 14th of January 201
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