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Effects of measurement statistics on the detection of damage in the Alamosa Canyon Bridge
This paper presents a comparison of the statistics on the measured model parameters of a bridge structure to the expected changes in those parameters caused by damage. It is then determined if the changes resulting from damage are statistically significant. This paper considers the most commonly used modal parameters for indication of damage: modal frequency, mode shape, and mode shape curvature. The approach is divided into two steps. First, the relative uncertainties (arising from random error sources) of the measured modal frequencies, mode shapes, and mode shape curvatures are determined by Monte Carlo analysis of the measured data. Based on these uncertainties, 95% statistical confidence bounds are computed for these parameters. The second step is the determination of the measured change in these parameters resulting from structural damage. Changes which are outside the 95% bounds are considered to be statistically significant. It is proposed that this statistical significance can be used to selectively filter which modes are used for damage identification. The primary conclusion of the paper is that the selection of the appropriate parameters to use in the damage identification algorithm must take into account not only the sensitivity of the damage indicator to the structural deterioration, but also the uncertainty inherent in the measurement of the parameters used to compute the indicator
Governing diversity: Dutch political parties' preferences on the role of the state in civic integration policies
This article analyses political debates about civic integration policies in the Netherlands, so as to identify different conceptions of the role of the state in ensuring social cohesion by governing diversity. Drawing on the literature on party systems, it presents an analysis of political party positions on the role of the state in civic integration along two dimensions: economic distribution on the one hand, and sociocultural governance on the other hand. I find that while the large majority of Dutch political parties adopt authoritarian positions on the sociocultural axis in favour of state intervention to protect Dutch culture and identity, their positions diverge significantly on the classic economic Left-Right dimension. The most contentious issue in Dutch civic integration politics is whether the state, the market or individual migrants should be responsible for financing and organising courses. Thus, this article proposes an innovative model for analysing the politics of citizenship, which enables us to comprehend how citizenship policies are shaped not only by views on how identity and culture relate to social cohesion, but also by diverging perspectives on socio-economic justice.Cities, Migration and Global Interdependenc
On the formation of a Hawking-radiation photosphere around microscopic black holes
We show that once a black hole surpasses some critical temperature
, the emitted Hawking radiation interacts with itself and forms a
nearly thermal photosphere. Using QED, we show that the dominant interactions
are bremsstrahlung and electron-photon pair production, and we estimate
, which when calculated more precisely is
found to be 45 GeV. The formation of the photosphere is
purely a particle physics effect, and not a general relativistic effect, since
the the photosphere forms roughly Schwarzschild radii away from
the black hole. The temperature of the photosphere decreases with distance
from the black hole, and the outer surface is determined by the constraint
(for the QED case), since this is the point at which electrons
and positrons annihilate, and the remaining photons free stream to infinity.
Observational consequences are discussed, and it is found that, although the
QED photosphere will not affect the Page-Hawking limits on primordial black
holes, which is most important for 100MeV black holes, the inclusion of QCD
interactions may significantly effect this limit, since for QCD we estimate
. The photosphere greatly reduces possibility of
observing individual black holes with temperatures greater than ,
since the high energy particles emitted from the black hole are processed
through the photosphere to a lower energy, where the gamma ray background is
much higher. The temperature of the plasma in the photosphere can be extremely
high, and this offers interesting possibilities for processes such as symmetry
restoration.Comment: Latex, 16 pages, 3 postscript figures, submitted to PRD. Also
available at http://fnas08.fnal.gov
Phenomenology of -CDM model: a possibility of accelerating Universe with positive pressure
Among various phenomenological models, a time-dependent model is selected here to investigate the -CDM cosmology.
Using this model the expressions for the time-dependent equation of state
parameter and other physical parameters are derived. It is shown that
in model accelerated expansion of the Universe takes place at negative
energy density, but with a positive pressure. It has also been possible to
obtain the change of sign of the deceleration parameter during cosmic
evolution.Comment: 16 Latex pages, 11 figures, Considerable modifications in the text;
Accepted in IJT
Clinical Outcomes in Patients with Type 2 Diabetes Mellitus and Peripheral Artery Disease: Results from the EXSCEL Trial
Background: Recent trials have identified anti-diabetes mellitus agents that lower major adverse cardiovascular event (MACE) rates, although some increase rates of lower-extremity amputation (LEA). Patients with peripheral artery disease (PAD) have greater incidence of diabetes mellitus and risk for LEA, prompting this investigation of clinical outcomes in patients with diabetes mellitus and PAD in the EXSCEL trial (Exenatide Study of Cardiovascular Event Lowering). Methods: EXSCEL evaluated the effects of once-weekly exenatide (a GLP-1 [glucagon-like peptide-1] receptor agonist) versus placebo on the rates of the primary composite MACE end point (cardiovascular death, myocardial infarction, or stroke) among patients with type 2 diabetes mellitus. In this post hoc analysis, we assessed the association of baseline PAD with rates of MACE, LEA, and the effects of exenatide versus placebo in patients with and without PAD. Results: EXSCEL included 2800 patients with PAD (19% of the trial population). These individuals had higher unadjusted and adjusted rates of MACE compared with patients without PAD (13.6% versus 11.4%, respectively) as well as a higher adjusted hazard ratio (adjusted hazard ratio, 1.13 [95% CI, 1.00-1.27]; P=0.047). Patients with PAD had higher all-cause mortality (adjusted hazard ratio 1.38 [95% CI, 1.20-1.60]; P<0.001) and more frequent LEA (adjusted hazard ratio 5.48 [95% CI, 4.16-7.22]; P<0.001). Patients treated with exenatide or placebo had similar rates of MACE and LEA, regardless of PAD status. Conclusions: EXSCEL participants with PAD had higher rates of all-cause mortality and LEA compared with those without PAD. There were no differences in MACE or LEA rates with exenatide versus placebo. Clinical Trial Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT01144338
Menus for Feeding Black Holes
Black holes are the ultimate prisons of the Universe, regions of spacetime
where the enormous gravity prohibits matter or even light to escape to
infinity. Yet, matter falling toward the black holes may shine spectacularly,
generating the strongest source of radiation. These sources provide us with
astrophysical laboratories of extreme physical conditions that cannot be
realized on Earth. This chapter offers a review of the basic menus for feeding
matter onto black holes and discusses their observational implications.Comment: 27 pages. Accepted for publication in Space Science Reviews. Also to
appear in hard cover in the Space Sciences Series of ISSI "The Physics of
Accretion onto Black Holes" (Springer Publisher
Detecting a stochastic gravitational wave background with the Laser Interferometer Space Antenna
The random superposition of many weak sources will produce a stochastic
background of gravitational waves that may dominate the response of the LISA
(Laser Interferometer Space Antenna) gravitational wave observatory. Unless
something can be done to distinguish between a stochastic background and
detector noise, the two will combine to form an effective noise floor for the
detector. Two methods have been proposed to solve this problem. The first is to
cross-correlate the output of two independent interferometers. The second is an
ingenious scheme for monitoring the instrument noise by operating LISA as a
Sagnac interferometer. Here we derive the optimal orbital alignment for
cross-correlating a pair of LISA detectors, and provide the first analytic
derivation of the Sagnac sensitivity curve.Comment: 9 pages, 11 figures. Significant changes to the noise estimate
Observing Supermassive Black Holes across cosmic time: from phenomenology to physics
In the last decade, a combination of high sensitivity, high spatial
resolution observations and of coordinated multi-wavelength surveys has
revolutionized our view of extra-galactic black hole (BH) astrophysics. We now
know that supermassive black holes reside in the nuclei of almost every galaxy,
grow over cosmological times by accreting matter, interact and merge with each
other, and in the process liberate enormous amounts of energy that influence
dramatically the evolution of the surrounding gas and stars, providing a
powerful self-regulatory mechanism for galaxy formation. The different
energetic phenomena associated to growing black holes and Active Galactic
Nuclei (AGN), their cosmological evolution and the observational techniques
used to unveil them, are the subject of this chapter. In particular, I will
focus my attention on the connection between the theory of high-energy
astrophysical processes giving rise to the observed emission in AGN, the
observable imprints they leave at different wavelengths, and the methods used
to uncover them in a statistically robust way. I will show how such a combined
effort of theorists and observers have led us to unveil most of the SMBH growth
over a large fraction of the age of the Universe, but that nagging
uncertainties remain, preventing us from fully understating the exact role of
black holes in the complex process of galaxy and large-scale structure
formation, assembly and evolution.Comment: 46 pages, 21 figures. This review article appears as a chapter in the
book: "Astrophysical Black Holes", Haardt, F., Gorini, V., Moschella, U and
Treves A. (Eds), 2015, Springer International Publishing AG, Cha
Dark matter and Colliders searches in the MSSM
We study the complementarity between dark matter experiments (direct
detection and indirect detections) and accelerator facilities (the CERN LHC and
a TeV Linear Collider) in the framework of the
constrained Minimal Supersymmetric Standard Model (MSSM). We show how
non--universality in the scalar and gaugino sectors can affect the experimental
prospects to discover the supersymmetric particles. The future experiments will
cover a large part of the parameter space of the MSSM favored by WMAP
constraint on the relic density, but there still exist some regions beyond
reach for some extreme (fine tuned) values of the supersymmetric parameters.
Whereas the Focus Point region characterized by heavy scalars will be easily
probed by experiments searching for dark matter, the regions with heavy
gauginos and light sfermions will be accessible more easily by collider
experiments. More informations on both supersymmetry and astrophysics
parameters can be thus obtained by correlating the different signals.Comment: 25 pages, 10 figures, corrected typos and reference adde
On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes
The sensitivity of a search for sources of TeV neutrinos can be improved by
grouping potential sources together into generic classes in a procedure that is
known as source stacking. In this paper, we define catalogs of Active Galactic
Nuclei (AGN) and use them to perform a source stacking analysis. The grouping
of AGN into classes is done in two steps: first, AGN classes are defined, then,
sources to be stacked are selected assuming that a potential neutrino flux is
linearly correlated with the photon luminosity in a certain energy band (radio,
IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino
production in AGN, this correlation is motivated by hadronic AGN models, as
briefly reviewed in this paper.
The source stacking search for neutrinos from generic AGN classes is
illustrated using the data collected by the AMANDA-II high energy neutrino
detector during the year 2000. No significant excess for any of the suggested
groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic
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