4,095 research outputs found
On the AGN radio luminosity distribution and the black hole fundamental plane
We have studied the dependence of the AGN nuclear radio (1.4 GHz) luminosity
on both the AGN 2-10 keV X-ray and the host-galaxy K-band luminosity. A
complete sample of 1268 X-ray selected AGN (both type 1 and type 2) has been
used, which is the largest catalogue of AGN belonging to statistically well
defined samples where radio, X and K band information exists. At variance with
previous studies, radio upper limits have been statistically taken into account
using a Bayesian Maximum Likelihood fitting method. It resulted that a good fit
is obtained assuming a plane in the 3D L_R-L_X-L_K space, namely logL_R= xi_X
logL_X + xi_K logL_K + xi_0, having a ~1 dex wide (1 sigma) spread in radio
luminosity. As already shown, no evidence of bimodality in the radio luminosity
distribution was found and therefore any definition of radio loudness in AGN is
arbitrary. Using scaling relations between the BH mass and the host galaxy
K-band luminosity, we have also derived a new estimate of the BH fundamental
plane (in the L_5GHz -L_X-M_BH space). Our analysis shows that previous
measures of the BH fundamental plane are biased by ~0.8 dex in favor of the
most luminous radio sources. Therefore, many AGN studies, where the BH
fundamental plane is used to investigate how AGN regulate their radiative and
mechanical luminosity as a function of the accretion rate, or many AGN/galaxy
co-evolution models, where radio-feedback is computed using the AGN fundamental
plane, should revise their conclusions.Comment: Submitted to MNRAS. Revised version after minor referee comments. 12
pages, 12 figure
The higher grading structure of the WKI hierarchy and the two-component short pulse equation
A higher grading affine algebraic construction of integrable hierarchies,
containing the Wadati-Konno-Ichikawa (WKI) hierarchy as a particular case, is
proposed. We show that a two-component generalization of the Sch\" afer-Wayne
short pulse equation arises quite naturally from the first negative flow of the
WKI hierarchy. Some novel integrable nonautonomous models are also proposed.
The conserved charges, both local and nonlocal, are obtained from the Riccati
form of the spectral problem. The loop-soliton solutions of the WKI hierarchy
are systematically constructed through gauge followed by reciprocal B\" acklund
transformation, establishing the precise connection between the whole WKI and
AKNS hierarchies. The connection between the short pulse equation with the
sine-Gordon model is extended to a correspondence between the two-component
short pulse equation and the Lund-Regge model
The algebraic structure behind the derivative nonlinear Schroedinger equation
The Kaup-Newell (KN) hierarchy contains the derivative nonlinear Schr\"
odinger equation (DNLSE) amongst others interesting and important nonlinear
integrable equations. In this paper, a general higher grading affine algebraic
construction of integrable hierarchies is proposed and the KN hierarchy is
established in terms of a Kac-Moody algebra and principal
gradation. In this form, our spectral problem is linear in the spectral
parameter. The positive and negative flows are derived, showing that some
interesting physical models arise from the same algebraic structure. For
instance, the DNLSE is obtained as the second positive, while the Mikhailov
model as the first negative flows, respectively. The equivalence between the
latter and the massive Thirring model is explicitly demonstrated also. The
algebraic dressing method is employed to construct soliton solutions in a
systematic manner for all members of the hierarchy. Finally, the equivalence of
the spectral problem introduced in this paper with the usual one, which is
quadratic in the spectral parameter, is achieved by setting a particular
automorphism of the affine algebra, which maps the homogeneous into principal
gradation.Comment: references adde
Factors associated with costs of hospitalization of severely mentally Ill patients
Background: Efforts to contain costs associated with general medical care include particular efforts for
psychiatric disorders. Hospitalization represents the largest component of costs for psychiatric care and there is
growing interest in balancing clinical needs against limiting costs of inpatient psychiatric care of patients with severe
mental illnesses. This study aimed to evaluate clinical factors associated with actual costs of inpatient psychiatric
care.
Method: We evaluated a cohort of 589 hospitalized psychiatric patients with severe mental illnesses at a
nonprofit, university-affiliated psychiatric hospital for factors associated with annualized total costs of inpatient care
over a three-year period, using bivariate and multivariate analyses.
Results: As expected, days-hospitalized was the major determinant of total costs of hospital care. In addition,
several clinical and treatment factors also were associated significantly and independently with costs in multivariate
modeling. These included presence of psychosis, electroconvulsive treatment, specialist consultations, use of
multiple antipsychotics or of clozapine, and being discharged to a supervised living arrangement, but not sex, age,
marital status, employment, or substance abuse.
Discussion: As expected, costs of psychiatric hospitalization were dominated by per-diem charges, but also
influenced by other, potentially modifiable treatment factors generally associated with more severe psychotic
illnesses. The study is based on actual costs rather than on insurer-reimbursements and a large study-sample,
though at a single institution. Specific factors identified encourage focusing on patient characteristics associated
with greater costs and redoubled efforts to apply and improve alternative, cost-effective interventions such as partialhospital
and intensive outpatient treatment
The BeppoSAX High Energy Large Area Survey (HELLAS) - VI. The radio properties
We present results of a complete radio follow-up obtained with the VLA and
ATCA radio telescopes down to a 6 cm flux limit of about 0.3 mJy of all the 147
X-ray sources detected in the BeppoSAX HELLAS survey. We found 53 X-ray/radio
likely associations, corresponding to about one third of the X-ray sample.
Using the two point spectral index alpha_ro=0.35 we divided all the HELLAS
X-ray sources in radio quiet and radio loud. We have 26 sources classified as
radio-loud objects, corresponding to about 18% of the HELLAS sample. In
agreement with previous results, the identified radio-loud sources are
associated mainly with Type 1 AGNs with L(5-10 keV) > 10^44 erg/s, while all
the identified Type 2 AGNs and Emission Line Galaxies are radio quiet objects
with L(5-10 keV) < 10^44 erg/s. The analysis of the radio spectral index
suggests that Type 1 AGNs have a mean radio spectral index flatter than Type 2
AGNs and Emission Line Galaxies.Comment: 12 pages, 5 figures, MNRAS, accepte
Aging-dependent functional alterations of mitochondrial DNA (mtDNA) from human fibroblasts transferred into mtDNA-less cells
To investigate the role that aging-dependent accumulation of mitochondrial DNA (mtDNA) mutations plays in the senescence processes, mitochondria from fibroblasts of 21 normal human individuals between 20 weeks (fetal) and 103 years of age were introduced into human mtDNA-less (ρ0) 206 cells by cytoplast × ρ0 cell fusion, and 7-31 transformant clones were isolated from each fusion. A slight cell donor age-dependent decrease in growth rate was detected in the transformants. Using an O2 consumption rate of 1 fmol/min/cell, which was not observed in any transformant among 158 derived from individuals 20 weeks (fetal) to 37 years of age, as a cut-off to identify respiratory-deficient clones, 11 such clones were found among 198 transformants derived from individuals 39-103 years of age. Furthermore, conventional and nonparametric analysis of the respiratory rates of 356 clones revealed a very significant decrease with donor age. In other analyses, a very significant age-dependent decline in the mtDNA content of the clones was observed, without, however, any significant correlation with the decrease in O2 consumption rate in the defective transformants. These observations clearly indicate the occurrence in the fibroblast-derived transformants of two independent, age-related functional alterations of mtDNA, presumably resulting from structural damage to this genome
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