4,476 research outputs found
A multidimensional approach to the measurement of poverty
By using fuzzy set theory a cross country multidimensional analysis of poverty is performed on the basis of ECHP data. A set of composite indicators is contructed in order to analyse different dimensions of poverty. For each indicator is calculated an unidimensional poverty ratio, thus allowing a comparison among countries and indicators on the dimensions of poverty. Finally, for each country a multidimensional poverty ratio is obtained.
Imprints of a high velocity wind on the soft x-ray spectrum of PG 1211+143
An extended XMM-Newton observation of the luminous narrow line Seyfert galaxy
PG 1211+143 in 2014 has revealed a more complex high velocity wind, with
components distinguished in velocity, ionization level, and column density.
Here we report soft x-ray emission and absorption features from the ionized
outflow, finding counterparts of both high velocity components, v ~ 0.129c and
v ~ 0.066c, recently identified in the highly ionized Fe K absorption spectrum.
The lower ionization of the co-moving soft x-ray absorbers imply a distribution
of higher density clouds embedded in the main outflow, while much higher column
densities for the same flow component in the hard x-ray spectra suggest
differing sight lines to the continuum x-ray source.Comment: 8 pages, 5 figures, 4 tables; Accepted for publication in MNRA
An Inkjet Printed Chipless RFID Sensor for Wireless Humidity Monitoring
A novel chipless RFID humidity sensor based on a finite Artificial Impedance
Surface (AIS) is presented. The unit cell of the AIS is composed of three
concentric loops thus obtaining three deep and high Q nulls in the
electromagnetic response of the tag. The wireless sensor is fabricated using
low-cost inkjet printing technology on a thin sheet of commercial coated paper.
The patterned surface is placed on a metal backed cardboard layer. The relative
humidity information is encoded in the frequency shift of the resonance peaks.
Varying the relative humidity level from 50% to 90%, the frequency shift has
proven to be up to 270MHz. The position of the resonance peaks has been
correlated to the relative humidity level of the environment on the basis of a
high number of measurements performed in a climatic chamber, specifically
designed for RF measurements of the sensor. A very low error probability of the
proposed sensor is demonstrated when the device is used with a 10% RH humidity
level discrimination
Latent class models in financial data analysis
This paper deals with optimal international portfolio choice by developing a latent class approach based on the distinction between international and non-international investors. On the basis of micro data, we analyze the effects of many social, demographic, economic and financial characteristics on the probability to be an international investor. Traditional measures of equity home bias do not allow for the existence of international investment rationing operators. On the contrary, by resorting to latent class analysis it is possible to detect the unobservable distinction between international investors and investors who are precluded from operating into international financial markets and, therefore, to evaluate the role of these unobservable constraints on equity home bias
Discovery of Broad Soft X-ray Absorption Lines from the Quasar Wind in PDS 456
High resolution soft X-ray spectroscopy of the prototype accretion disk wind
quasar, PDS 456, is presented. Here, the XMM-Newton RGS spectra are analyzed
from the large 2013-2014 XMM-Newton campaign, consisting of 5 observations of
approximately 100 ks in length. During the last observation (hereafter OBS. E),
the quasar is at a minimum flux level and broad absorption line profiles are
revealed in the soft X-ray band, with typical velocity widths of km s. During a period of higher flux in the 3rd and 4th
observations (OBS. C and D, respectively), a very broad absorption trough is
also present above 1 keV. From fitting the absorption lines with models of
photoionized absorption spectra, the inferred outflow velocities lie in the
range . The absorption lines likely originate from He and H-like
neon and L-shell iron at these energies. Comparison with earlier archival data
of PDS 456 also reveals similar absorption structure near 1 keV in a 40 ks
observation in 2001, and generally the absorption lines appear most apparent
when the spectrum is more absorbed overall. The presence of the soft X-ray
broad absorption lines is also independently confirmed from an analysis of the
XMM-Newton EPIC spectra below 2 keV. We suggest that the soft X-ray absorption
profiles could be associated with a lower ionization and possibly clumpy phase
of the accretion disk wind, where the latter is known to be present in this
quasar from its well studied iron K absorption profile and where the wind
velocity reaches a typical value of 0.3.Comment: 44 pages, including 13 figures, accepted for publication in The
Astrophysical Journa
Short term X-ray spectral variability of the quasar PDS 456 observed in a low flux state
We present an analysis of the 2013 Suzaku campaign on the nearby luminous
quasar PDS 456, covering a total duration of ~1 Ms and a net exposure of 455
ks. During these observations, the X-ray flux was suppressed by a factor of >10
in the soft X-ray band when compared to other epochs. We investigated the
broadband continuum by constructing a spectral energy distribution, making use
of the optical/UV photometry and hard X-ray spectra from the later
XMM-Newton/NuSTAR campaign in 2014. The high energy part of this low flux state
cannot be accounted for by self-consistent accretion disc and corona models
without attenuation by absorbing gas, which partially covers a substantial
fraction of the line of sight towards the X-ray source. Two absorption layers
are required, of column density and ,
with average covering factors of ~80% (with typical 5% variations) and 60%
(10-15%), respectively. In these observations PDS 456 displays significant
short term X-ray spectral variability, on timescales of ~100 ks, which can be
accounted for by variable covering of the absorbing gas. The partial covering
absorber prefers an outflow velocity of at
the >99.9% confidence level over the case where . This is
consistent with the velocity of the highly ionised outflow responsible for the
blueshifted iron K absorption profile. We therefore suggest that the partial
covering clouds could be the denser, or clumpy part of an inhomogeneous
accretion disc wind. Finally we estimate the size-scale of the X-ray source
from its variability. The radial extent of the X-ray emitter is found to be of
the order ~15-20 , although the hard X-ray (>2 keV) emission may
originate from a more compact or patchy corona of hot electrons, which is ~6-8
in size.Comment: 38 pages, 13 figures, accepted for publication in MNRA
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