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Improving Visual Field Examination of the Macula Using Structural Information
Purpose: To investigate a novel approach for structure-function modeling in glaucoma to improve visual field testing in the macula.
Methods: We acquired data from the macular region in 20 healthy eyes and 31 with central glaucomatous damage. Optical coherence tomography (OCT) scans were used to estimate the local macular ganglion cell density. Perimetry was performed with a fundus-tracking device using a 10-2 grid. OCT scans were matched to the retinal image from the fundus perimeter to accurately map the tested locations onto the structural damage. Binary responses from the subjects to all presented stimuli were used to calculate the structure-function model used to generate prior distributions for a ZEST (Zippy Estimation by Sequential Testing) Bayesian strategy. We used simulations based on structural and functional data acquired from an independent dataset of 20 glaucoma patients to compare the performance of this new strategy, structural macular ZEST (MacS-ZEST), with a standard ZEST.
Results: Compared to the standard ZEST, MacS-ZEST reduced the number of presentations by 13% in reliable simulated subjects and 14% with higher rates (â„20%) of false positive or false negative errors. Reduction in mean absolute error was not present for reliable subjects but was gradually more important with unreliable responses (â„10% at 30% error rate).
Conclusions: Binary responses can be modeled to incorporate detailed structural information from macular OCT into visual field testing, improving overall speed and accuracy in poor responders.
Translational Relevance: Structural information can improve speed and reliability for macular testing in glaucoma practice
Chemical abundances and properties of the ionized gas in NGC 1705
We obtained [O III] narrow-band imaging and multi-slit MXU spectroscopy of
the blue compact dwarf (BCD) galaxy NGC 1705 with FORS2@VLT to derive chemical
abundances of PNe and H II regions and, more in general, to characterize the
properties of the ionized gas. The auroral [O III]\lambda4363 line was detected
in all but one of the eleven analyzed regions, allowing for a direct estimate
of their electron temperature. The only object for which the [O III]\lambda4363
line was not detected is a possible low-ionization PN, the only one detected in
our data. For all the other regions, we derived the abundances of Nitrogen,
Oxygen, Neon, Sulfur and Argon out to ~ 1 kpc from the galaxy center. We detect
for the first time in NGC 1705 a negative radial gradient in the oxygen
metallicity of -0.24 \pm 0.08 dex kpc^{-1}. The element abundances are all
consistent with values reported in the literature for other samples of dwarf
irregular and blue compact dwarf galaxies. However, the average (central)
oxygen abundance, 12 + log(O/H)=7.96 \pm 0.04, is ~0.26 dex lower than previous
literature estimates for NGC 1705 based on the [O III]\lambda4363 line. From
classical emission-line diagnostic diagrams, we exclude a major contribution
from shock excitation. On the other hand, the radial behavior of the emission
line ratios is consistent with the progressive dilution of radiation with
increasing distance from the center of NGC 1705. This suggests that the
strongest starburst located within the central 150 pc is responsible for
the ionization of the gas out to at least 1 kpc. The gradual dilution of
the radiation with increasing distance from the center reflects the gradual and
continuous transition from the highly ionized H II regions in the proximity of
the major starburst into the diffuse ionized gas.Comment: Accepted for publication on A
Chemical abundances in the nucleus of the Sagittarius dwarf spheroidal galaxy
We present Iron, Magnesium, Calcium, and Titanium abundances for 235 stars in
the central region of the Sagittarius dwarf spheroidal galaxy (within 9.0
arcmin ~70 pc from the center) from medium-resolution Keck/DEIMOS spectra. All
the considered stars belong to the massive globular cluster M54 or to the
central nucleus of the galaxy (Sgr,N). In particular we provide abundances for
109 stars with [Fe/H] > -1.0, more than doubling the available sample of
spectroscopic metallicity and alpha-elements abundance estimates for Sgr dSph
stars in this metallicity regime. Also, we find the first confirmed member of
the Sagittarius dwarf spheroidal with [Fe/H]< -2.0 based on analysis of iron
lines. We find for the first time a metallicity gradient in the Sgr,N
population, whose peak iron abundance goes from [Fe/H]=-0.38 for R < 2.5 arcmin
to [Fe/H]=-0.57 for 5.0 < R < 9.0 arcmin. On the other hand the trends of
[Mg/Fe], [Ca/Fe], and [Ti/Fe] with [Fe/H] are the same over the entire region
explored by our study. We reproduce the observed chemical patterns of the
Sagittarius dwarf spheroidal as a whole with a chemical evolution model
implying a high mass progenitor ( M_(DM)=6 X 10^{10} Msun ) and a significant
event of mass-stripping occurred a few Gyr ago, presumably starting at the
first peri-Galactic passage after infall.Comment: Accepted for publication to A&A, 12 pages, 14 figures, 1 tabl
Resonating bipolarons
Electrons coupled to local lattice deformations end up in selftrapped
localized molecular states involving their binding into bipolarons when the
coupling is stronger than a certain critical value. Below that value they exist
as essentially itinerant electrons. We propose that the abrupt crossover
between the two regimes can be described by resonant pairing similar to the
Feshbach resonance in binary atomic collision processes. Given the
intrinsically local nature of the exchange of pairs of itinerant electrons and
localized bipolarons, we demonstrate the occurrence of such a resonance on a
finite-size cluster made out of metallic atoms surrounding a polaronic ligand
center.Comment: 7 pages, 4 figures, to be published in Europhysics Letter
Orchestrating Forest Policy in Italy: Mission Impossible?
In the Italian political and economic agenda the forest sector occupies a marginal role. The forest sector in Italy is characterized by a high institutional fragmentation and centralized decision-making processes dominated by Public Forest Administrations. Public participation in forest policy processes has been implemented since the 1990s at national, regional and local levels in several cases. However, today no significant changes have been observed in the overall governance of the forest sector and stakeholders' involvement in Italian forest policy decision-making is still rather limited. The aims of this paper are to describe the state of forest-related participatory processes in Italy at various levels (national, regional and local) and identify which factors and actors hinder or support the establishment and implementation of participatory forest-related processes in the country. The forest-related participatory processes are analyzed adopting a qualitative-based approach and interpreting interactive, complex and non-linear participatory processes through the lens of panarchy theory
The 2003 eclipse of EE Cep is coming. A review of past eclipses
EE Cep is an eclipsing binary with a period of 5.6 years. The next eclipse
will occur soon, in May-June 2003, and all available past eclipses were
collected and briefly analysed. EE Cep shows very large changes of the shape
and the depth of minima during different eclipses, however it is possible to
single out some persistent features. The analysis suggests that the eclipsing
body should be a long object surrounded by an extended semi-transparent
envelope. As an explanation, a model of a precessing optically thick disc,
inclined to the plane of the binary orbit, is invoked. The changes of its
spatial orientation, which is defined by the inclination of the disc and the
tilt, induced most probably by precession of the disc spin axis with a period
of about 50 years, produce strange photometric behaviour of this star. The
H_alpha emission, and possibly the NaI absorptions, show significant changes
during several months outside of the eclipse phase.Comment: 7 pages, 7 figures, LaTeX2e, accepted by A&
Evolution of Phase-Space Density in Dark Matter Halos
The evolution of the phase-space density profile in dark matter (DM) halos is
investigated by means of constrained simulations, designed to control the
merging history of a given DM halo. Halos evolve through a series of quiescent
phases of a slow accretion intermitted by violent events of major mergers. In
the quiescent phases the density of the halo closely follows the NFW profile
and the phase-space density profile, Q(r), is given by the Taylor & Navarro
power law, r^{-beta}, where beta ~ 1.9 and stays remarkably stable over the
Hubble time. Expressing the phase-space density by the NFW parameters, Q(r)=Qs
(r/Rs)^{-beta}, the evolution of Q is determined by Qs. We have found that the
effective mass surface density within Rs, Sigma_s = rhos Rs, remains constant
throughout the evolution of a given DM halo along the main branch of its
merging tree. This invariance entails that Qs ~ Rs^{-5/2} and Q(r) ~
Sigma_s^{-1/2} Rs^{-5/2} (r/ Rs)^{-beta}. It follows that the phase-space
density remains constant, in the sense of Qs=const., in the quiescent phases
and it decreases as Rs^{-5/2} in the violent ones. The physical origin of the
NFW density profile and the phase-space density power law is still unknown.
Yet, the numerical experiments show that halos recover these relations after
the violent phases. The major mergers drive Rs to increase and Qs to decrease
discontinuously while keeping Qs Rs^{5/2} = const. The virial equilibrium in
the quiescent phases implies that a DM halos evolves along a sequence of NFW
profiles with constant energy per unit volume (i.e., pressure) within Rs.Comment: 7 pages, 5 figures, accepted by the Astrophysical Journal. Revised, 2
figures adde
Detecting anomalies in water distribution networks using EPR modelling paradigm
This is the author accepted manuscript. The final version is available from IWA Publishing via the DOI in this record.Sustainable management of water distribution networks (WDNs) requires effective exploitation of available data from pressure/flow devices. Water companies collect a large amount of such data, which need to be managed correctly and analysed effectively using appropriate techniques. Furthermore, water companies need to balance the data gathering and handling costs with the benefits of extracting useful information. Recent approaches implementing data mining techniques for analysing pressure/flow data appear very promising, because they can automate mundane tasks involved in data analysis process and efficiently deal with sensor data collected. Furthermore, they rely on empirical observations of a WDN behaviour over time, allowing reproducing/predicting possible future behaviour of the network. This paper investigates the effectiveness of the evolutionary polynomial regression (EPR) paradigm to reproduce the behaviour of a WDN using online data recorded by low-cost pressure/flow devices. Using data from a real district metered area, the case study presented shows that by using the EPR paradigm a model can be built which enables the accurate reproduction and prediction of the WDN behaviour over time and detection of flow anomalies due to possible unreported bursts or unknown increase of water withdrawal. Such an EPR model might be integrated into an early warning system to raise alarms when anomalies are detected.The research reported in this paper was founded by two projects of the Italian Scientific Research Program of National Interest PRIN-2012: âAnalysis tools for management of water losses in urban aqueductsâ and âTools and procedures for advanced and sustainable management of water distribution networksâ
PNe and H II regions in the starburst irregular galaxy NGC 4449 from LBT MODS data
We present deep 350010000 spectra of H II regions and planetary
nebulae (PNe) in the starburst irregular galaxy NGC 4449, acquired with the
Multi Object Double Spectrograph at the Large Binocular Telescope. Using the
"direct" method, we derived the abundance of He, N, O, Ne, Ar, and S in six H
II regions and in four PNe in NGC 4449. This is the first case of PNe studied
in a starburst irregular outside the Local Group. Our H II region and PN sample
extends over a galacto-centric distance range of 2 kpc and spans
0.2 dex in oxygen abundance, with average values of and for H II regions and PNe, respectively. PNe and H
II regions exhibit similar oxygen abundances in the galacto-centric distance
range of overlap, while PNe appear more than 1 dex enhanced in nitrogen
with respect to H II regions. The latter result is the natural consequence of N
being mostly synthesized in intermediate-mass stars and brought to the stellar
surface during dredge-up episodes. On the other hand, the similarity in O
abundance between H II regions and PNe suggests that NGC 4449' s interstellar
medium has been poorly enriched in elements since the progenitors of
the PNe were formed. Finally, our data reveal the presence of a negative oxygen
gradient for both H II regions and PNe, whilst nitrogen does not exhibit any
significant radial trend. We ascribe the (unexpected) nitrogen behaviour as due
to local N enrichment by the conspicuous Wolf-Rayet population in NGC 4449.Comment: Accepted for publication on Ap
Dyadic analysis for multi-block data in sport surveys analytics
Analyzing sports data has become a challenging issue as it involves not standard data structures coming from several sources and with different formats, being often high dimensional and complex. This paper deals with a dyadic structure (athletes/coaches), characterized by a large number of manifest and latent variables. Data were collected in a survey administered within a joint project of University of Naples Federico II and Italian Swimmer Federation. The survey gathers information about psychosocial aspects influencing swimmersâ performance. The paper introduces a data processing method for dyadic data by presenting an alternative approach with respect to the current used models and provides an analysis of psychological factors affecting the actor/partner interdependence by means of a quantile regression. The obtained results could be an asset to design strategies and actions both for coaches and swimmers establishing an original use of statistical methods for analysing athletes psychological behaviour
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