10,335 research outputs found
The Effect of the AGN Feedback on the Interstellar Medium of Early-Type Galaxies: 2D Hydrodynamical Simulations of the Low-Rotation Case
We present 2D hydrodynamical simulations for the evolution of early-type
galaxies containing central massive black holes (MBHs), starting at age 2 Gyr.
The code contains accurate and physically consistent radiative and mechanical
AGN wind feedback, with parsec-scale central resolution. Mass input comes from
stellar evolution; energy input includes Type Ia and II supernova and stellar
heating; star-formation is included. Realistic, axisymmetric dynamical models
for the galaxies are built solving the Jeans' equations. The lowest mass models
(Mstar = 8 10^{10}Msun) develop global outflows sustained by SNIa's heating,
ending with a significantly lower amount of hot gas and new stars. In more
massive models, nuclear outbursts last to the present epoch, with large and
frequent fluctuations in nuclear emission and from the gas (Lx). Each burst
last ~ 10^{7.5} yr, during which (for r < 2-3 kpc) cold, inflowing, and hot,
outflowing gas phases coexist. The Lx-T relation for the gas matches that of
local galaxies. AGN activity causes positive feedback for star formation.
Roughly half of the total mass loss is recycled into new stars (DeltaMstar),
just ~ 3% of it is accreted on the MBH, the remainder being ejected from the
galaxy. The ratio between the mass of gas expelled to that in to new stars, the
load factor, is ~0.6. Rounder galaxies shapes lead to larger final MBH masses,
DeltaMstar, and Lx. Almost all the time is spent at very low nuclear
luminosities, yet one quarter of the total energy is emitted at an Eddington
ratio > 0.1. The duty-cycle of AGN activity approximates 4% (Abridged).Comment: 26 pages, 15 figure, submitted to ApJ. Comments welcom
Cut-free Calculi and Relational Semantics for Temporal STIT Logics
We present cut-free labelled sequent calculi for a central formalism in logics of agency: STIT logics with temporal operators. These include sequent systems for Ldm , Tstit and Xstit. All calculi presented possess essential structural properties such as contraction- and cut-admissibility. The labelled calculi G3Ldm and G3Tstit are shown sound and complete relative to irreflexive temporal frames. Additionally, we extend current results by showing that also Xstit can be characterized through relational frames, omitting the use of BT+AC frames
Effect of Al doping on the optical phonon spectrum in Mg(1-x)Al(x)B(2)
Raman and infrared absorption spectra of Mg(1-x)Al(x)B(2) have been collected
for 0<x<0.5 in the spectral range of optical phonons. The x-dependence of the
peak frequency, the width and the intensity of the observed Raman lines has
been carefully analized. A peculiar x-dependence of the optical modes is
pointed out for two different Al doping ranges. In particular the onset of the
high-doping structural phase previously observed in diffraction measurements is
marked by the appearence of new spectral components at high frequencies. A
connection between the whole of our results and the observed suppression of
superconductivity in the high doping region is established
On The Low-Frequency Vibrational Modes of C
The vibrational spectrum of C is compared to the spectrum of a
classical isotropic elastic spherical shell. We show correlations between the
low frequency modes of C and those of the spherical shell. We find the
spherical model gives the approximate frequency ordering for the low frequency
modes. We estimate a Poisson ratio of and a transverse
speed of sound of m/s for the equivalent elastic shell. We
also find that for the
shell modes and , independent of elastic constants. We
find that this ratio compares favorably with an experimental value of 1.17.Comment: 11 pages, 3 figures in Postscript, uses REVTEX, to be published in
Chem. Phys. Let
Rain estimation from satellites: An examination of the Griffith-Woodley technique
The Griffith-Woodley Technique (GWT) is an approach to estimating precipitation using infrared observations of clouds from geosynchronous satellites. It is examined in three ways: an analysis of the terms in the GWT equations; a case study of infrared imagery portraying convective development over Florida; and the comparison of a simplified equation set and resultant rain map to results using the GWT. The objective is to determine the dominant factors in the calculation of GWT rain estimates. Analysis of a single day's convection over Florida produced a number of significant insights into various terms in the GWT rainfall equations. Due to the definition of clouds by a threshold isotherm the majority of clouds on this day did not go through an idealized life cycle before losing their identity through merger, splitting, etc. As a result, 85% of the clouds had a defined life of 0.5 or 1 h. For these clouds the terms in the GWT which are dependent on cloud life history become essentially constant. The empirically derived ratio of radar echo area to cloud area is given a singular value (0.02) for 43% of the sample, while the rainrate term is 20.7 mmh-1 for 61% of the sample. For 55% of the sampled clouds the temperature weighting term is identically 1.0. Cloud area itself is highly correlated (r=0.88) with GWT computed rain volume. An important, discriminating parameter in the GWT is the temperature defining the coldest 10% cloud area. The analysis further shows that the two dominant parameters in rainfall estimation are the existence of cold cloud and the duration of cloud over a point
Cancer mortality in Europe, 2000-2004, and an overview of trends since 1975
Background: To update the pattern of cancer mortality in Europe. Materials and methods: We analysed cancer mortality in 34 European countries during 2000-2004, with an overview of trends in 1975-2004 using data from the World Health Organization. Results: From 1990-1994 to 2000-2004, overall cancer mortality in the European Union declined from 185.2 to 168.0/100 000 (world standard, −9%) in men and from 104.8 to 96.9 (−8%) in women, with larger falls in middle age. Total cancer mortality trends were favourable, though to a variable degree, in all major European countries, including Russia, but not in Romania. The major determinants of these favourable trends were the decline of lung (−16%) and other tobacco-related cancers in men, together with the persistent falls in gastric cancer, and the recent appreciable falls in colorectal cancer. In women, relevant contributions came from the persistent decline in cervical cancer and the recent falls in breast cancer mortality, particularly in northern and western Europe. Favourable trends were also observed for testicular cancer, Hodgkin lymphomas, leukaemias, and other neoplasms amenable to treatment, though the reductions were still appreciably smaller in eastern Europe. Conclusion: This updated analysis of cancer mortality in Europe showed a persistent favourable trend over the last year
A comparison of trends in mortality from primary liver cancer and intrahepatic cholangiocarcinoma in Europe
Background To update and compare mortality from primary liver cancer (PLC) and intrahepatic cholangiocarcinoma (ICC) in Europe in 1990-2010. Materials and methods We used data from the World Health Organization (WHO) to compute age-standardized (world population) mortality rates, and used joinpoint analysis to identify substantial changes. Results Between 2002 and 2007, PLC rates in the European Union (EU) declined from 3.9 to 3.6/100 000 men. Around 2007, the highest male rates were in France (6.2/100 000), Spain (4.9), and Italy (4.0), while the lowest ones were in Sweden (1.1), the Netherlands (1.2), and the UK (1.8). In women, mortality was lower (0.8/100 000 in 2007 in the EU), and showed more favourable trends, with a decline of over 2% per year over the last two decades as compared with 0.4% in men, in the EU. In contrast, the EU mortality from ICC increased by around 9% in both sexes from 1990 to 2008, reaching rates of 1.1/100 000 men and 0.75/100 000 women. The highest rates were in UK, Germany, and France (1.2-1.5/100 000 men, 0.8-1.1/100 000 women). Conclusions PLC mortality has become more uniform across Europe over recent years, with an overall decline; in contrast, ICC mortality has substantially increased in most Europ
European cancer mortality predictions for the year 2012
Background: Estimating current cancer mortality figures is important for defining priorities for prevention and treatment. Materials and methods: Using logarithmic Poisson count data joinpoint models on mortality and population data from the World Health Organization database, we estimated numbers of deaths and age-standardized rates in 2012 from all cancers and selected cancer sites for the whole European Union (EU) and its six more populated countries. Results: Cancer deaths in the EU in 2012 are estimated to be 1 283 101 (717 398 men and 565 703 women) corresponding to standardized overall cancer death rates of 139/100 000 men and 85/100 000 women. The fall from 2007 was 10% in men and 7% in women. In men, declines are predicted for stomach (−20%), leukemias (−11%), lung and prostate (−10%) and colorectal (−7%) cancers, and for stomach (−23%), leukemias (−12%), uterus and colorectum (−11%) and breast (−9%) in women. Almost stable rates are expected for pancreatic cancer (+2-3%) and increases for female lung cancer (+7%). Younger women show the greatest falls in breast cancer mortality rates in the EU (−17%), and declines are expected in all individual countries, except Poland. Conclusion: Apart for lung cancer in women and pancreatic cancer, continuing falls are expected in mortality from major cancers in the E
No measure for culture? Value in the new economy
This paper explores articulations of the value of investment in culture and the arts through a critical discourse analysis of policy documents, reports and academic commentary since 1997. It argues that in this period, discourses around the value of culture have moved from a focus on the direct economic contributions of the culture industries to their indirect economic benefits. These indirect benefits are discussed here under three main headings: creativity and innovation, employability, and social inclusion. These are in turn analysed in terms of three forms of capital: human, social and cultural. The paper concludes with an analysis of this discursive shift through the lens of autonomist Marxist concerns with the labour of social reproduction. It is our argument that, in contemporary policy discourses on culture and the arts, the government in the UK is increasingly concerned with the use of culture to form the social in the image of capital. As such, we must turn our attention beyond the walls of the factory in order to understand the contemporary capitalist production of value and resistance to it. </jats:p
A Semantic Grid Oriented to E-Tourism
With increasing complexity of tourism business models and tasks, there is a
clear need of the next generation e-Tourism infrastructure to support flexible
automation, integration, computation, storage, and collaboration. Currently
several enabling technologies such as semantic Web, Web service, agent and grid
computing have been applied in the different e-Tourism applications, however
there is no a unified framework to be able to integrate all of them. So this
paper presents a promising e-Tourism framework based on emerging semantic grid,
in which a number of key design issues are discussed including architecture,
ontologies structure, semantic reconciliation, service and resource discovery,
role based authorization and intelligent agent. The paper finally provides the
implementation of the framework.Comment: 12 PAGES, 7 Figure
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