Health utility bias: A meta-analytic evaluation

A common assertion is that rating scale (RS) values are lower than both standard gamble (SG) and time tradeoff (TTO) values. However, differences among these methods may be due to method specific bias. While SG and TTO suffer systematic bias, RS responses are known to depend on the range and frequency of other health states being evaluated. Over many diverse studies this effect is predicted to diminish. Thus, a systematic review and data synthesis of RS-TTO and RS-SG difference scores may better reveal persistent dissimilarities. PURPOSE: To establish through systematic review and meta-analysis the net effect of biases that endure over many studies of utilities

Impacts of catastrophic earthquakes on the insect communities in estuarine mangroves, Northern Taiwan

As a catastrophic earthquake is unpredictable and occurs only occasionally, impacts on biotic communities are seldom known. Monthly changes in insect communities in the mangroves along the Danshui Estuary were monitored for more than 3 years from before and after two catastrophic earthquakes in Taiwan the Chi-Chi earthquake (M-L = 7.3) of September 21, 1999 and the 3-31 earthquake (M-L = 6.8) of March 31, 2002. Here we show that the Chi-Chi earthquake not only caused large declines in total individual number but also total species number of insects. It also resulted in greater variability among samples, and shifts in insect communities. Non-biting midges and rove beetles, whose immatures inhabited the riparian underground or aquatic sediments, were most severely affected. By 7 months after the Chi-Chi earthquake, the insect communities had recovered to a level comparable to that before the earthquake. However, the influence of the 3-31 earthquake on the insect communities was less severe. It is concluded that the more-severe impacts of the Chi-Chi earthquake than the 3-31 earthquake can be attributable to differences in ground shaking, occurrence time, biodiversity, and growing conditions of insects at those times

High performance Beowulf computer for lattice QCD

We describe the construction of a high performance parallel computer composed of PC components, as well as the performance test in lattice QCD.Comment: Lattice 2001 (Algorithms and Machines) 3 page

High-resolution UV spectrum of the benzene—N2 van der Waals complex

The rotationally resolved spectrum of the 610 band of the S1 ← S0 electronic transition of the benzene—N2 van der Waals complex has been recorded and 119 transitions assigned. The C6H6·N2 complex, produced in a pulsed molecular beam, was detected by mass-selected two-photon two-colour ionization employing a high-resolution (ΔνUV = 100 MHz, fwhm) pulsed-amplified cw laser for the resonant intermediate excitation. The observed rotational structure is that of a rigid symmetric top with weaker additional rotational transitions most likely arising from the free internal rotation of the N2 in the plane parallel to the benzene ring. The N2 is located parallel to the benzene ring at a distance of 3.50 Å; this decreases by 45 mÅ in the excited electronic state

Blow up criterion for compressible nematic liquid crystal flows in dimension three

In this paper, we consider the short time strong solution to a simplified hydrodynamic flow modeling the compressible, nematic liquid crystal materials in dimension three. We establish a criterion for possible breakdown of such solutions at finite time in terms of the temporal integral of both the maximum norm of the deformation tensor of velocity gradient and the square of maximum norm of gradient of liquid crystal director field.Comment: 22 page

Role of Umklapp Processes in Conductivity of Doped Two-Leg Ladders

Recent conductivity measurements performed on the hole-doped two-leg ladder material $\mathrm{Sr_{14-x}Ca_xCu_{24}O_{41}}$ reveal an approximately linear power law regime in the c-axis DC resistivity as a function of temperature for $x=11$. In this work, we employ a bosonic model to argue that umklapp processes are responsible for this feature and for the high spectral weight in the optical conductivity which occurs beyond the finite frequency Drude-like peak. Including quenched disorder in our model allows us to reproduce experimental conductivity and resistivity curves over a wide range of energies. We also point out the differences between the effect of umklapp processes in a single chain and in the two-leg ladder.Comment: 10 pages, 2 figure

A simple variational approach to the quantum Frenkel-Kontorova model

We present a simple and complete variational approach to the one-dimensional quantum Frenkel-Kontorova model. Dirac's time-dependent variational principle is adopted together with a Hatree-type many-body trial wavefunction for the atoms. The single-particle state is assumed to have the Jackiw-Kerman form. We obtain an effective classical Hamiltonian for the system which is simple enough for a complete numerical solution for the static ground state of the model. Numerical results show that our simple approach captures the essence of the quantum effects first observed in quantum Monte Carlo studies.Comment: 12 pages, 2 figure

Strings in Homogeneous Background Spacetimes

The string equations of motion for some homogeneous (Kantowski-Sachs, Bianchi I and Bianchi IX) background spacetimes are given, and solved explicitly in some simple cases. This is motivated by the recent developments in string cosmology, where it has been shown that, under certain circumstances, such spacetimes appear as string-vacua. Both tensile and null strings are considered. Generally, it is much simpler to solve for the null strings since then we deal with the null geodesic equations of General Relativity plus some additional constraints. We consider in detail an ansatz corresponding to circular strings, and we discuss the possibility of using an elliptic-shape string ansatz in the case of homogeneous (but anisotropic) backgrounds.Comment: 25 pages, REVTE

Outer Regions of the Milky Way

With the start of the Gaia era, the time has come to address the major challenge of deriving the star formation history and evolution of the disk of our MilkyWay. Here we review our present knowledge of the outer regions of the Milky Way disk population. Its stellar content, its structure and its dynamical and chemical evolution are summarized, focussing on our lack of understanding both from an observational and a theoretical viewpoint. We describe the unprecedented data that Gaia and the upcoming ground-based spectroscopic surveys will provide in the next decade. More in detail, we quantify the expect accuracy in position, velocity and astrophysical parameters of some of the key tracers of the stellar populations in the outer Galactic disk. Some insights on the future capability of these surveys to answer crucial and fundamental issues are discussed, such as the mechanisms driving the spiral arms and the warp formation. Our Galaxy, theMilkyWay, is our cosmological laboratory for understanding the process of formation and evolution of disk galaxies. What we learn in the next decades will be naturally transferred to the extragalactic domain.Comment: 22 pages, 10 figures, Invited review, Book chapter in "Outskirts of Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and Space Science Library, Springer, in pres

Image tag completion by local learning

The problem of tag completion is to learn the missing tags of an image. In this paper, we propose to learn a tag scoring vector for each image by local linear learning. A local linear function is used in the neighborhood of each image to predict the tag scoring vectors of its neighboring images. We construct a unified objective function for the learning of both tag scoring vectors and local linear function parame- ters. In the objective, we impose the learned tag scoring vectors to be consistent with the known associations to the tags of each image, and also minimize the prediction error of each local linear function, while reducing the complexity of each local function. The objective function is optimized by an alternate optimization strategy and gradient descent methods in an iterative algorithm. We compare the proposed algorithm against different state-of-the-art tag completion methods, and the results show its advantages