bluuebunny/crossref_metadata_2025 huggingface dataset:
Instability and sensitivity of the flow around a rotating circular cylinder
Authors: PRALITS JAN O. , BRANDT LUCA , GIANNETTI FLAVIO
Published: March 2010

The two-dimensional flow around a rotating circular cylinder is studied at Re = 100. The instability mechanisms for the first and second shedding modes are analysed. The region in the flow with a role of ‘wavemaker’ in the excitation of the global instability is identified by considering the structural sensitivity of the unstable mode. This approach is compared with the analysis of the perturbation kinetic energy production, a classic approach in linear stability analysis. Multiple steady-state solutions are found at high rotation rates, explaining the quenching of the second shedding mode. Turning points in phase space are associated with the movement of the flow stagnation point. In addition, a method to examine which structural variation of the base flow has the largest impact on the instability features is proposed. This has relevant implications for the passive control of instabilities. Finally, numerical simulations of the flow are performed to verify that the structural sensitivity analysis is able to provide correct indications on where to position passive control devices, e.g. small obstacles, in order to suppress the shedding modes.
Task space control of mobile manipulators
Authors: Galicki Mirosław
Published: March 2010

This study offers the solution of the end-effector trajectory tracking problem subject to state constraints, suitably transformed into control-dependent ones, for mobile manipulators. Based on the Lyapunov stability theory, a class of controllers fulfilling the above constraints and generating the mobile manipulator trajectory with (instantaneous) minimal energy, is proposed. The problem of manipulability enforcement is solved here based on an exterior penalty function approach which results in continuous mobile manipulator controls even near boundaries of state constraints. The numerical simulation results carried out for a mobile manipulator consisting of a non-holonomic unicycle and a holonomic manipulator of two revolute kinematic pairs, operating in a two-dimensional task space, illustrate the performance of the proposed controllers.
DECONVOLUTING PREFERENCES AND ERRORS: A MODEL FOR BINOMIAL PANEL DATA
Authors: Fosgerau Mogens , Nielsen Søren Feodor
Published: March 2010

In many stated choice experiments researchers observe the random variablesVt,Xt, andYt= 1{U+δ⊤Xt+ εt<Vt},t≤T, whereδis an unknown parameter andUand εtare unobservable random variables. We show that under weak assumptions the distributions ofUand εtand also the unknown parameterδcan be consistently estimated using a sieved maximum likelihood estimation procedure.
Modeling the contribution of phonotactic cues to the problem of word segmentation
Authors: BLANCHARD DANIEL , HEINZ JEFFREY , GOLINKOFF ROBERTA
Published: March 2010

How do infants find the words in the speech stream? Computational models help us understand this feat by revealing the advantages and disadvantages of different strategies that infants might use. Here, we outline a computational model of word segmentation that aims both to incorporate cues proposed by language acquisition researchers and to establish the contributions different cues can make to word segmentation. We present experimental results from modified versions of Venkataraman's (2001) segmentation model that examine the utility of: (1) language-universal phonotactic cues; (2) language-specific phonotactic cues which must be learned while segmenting utterances; and (3) their combination. We show that the language-specific cue improves segmentation performance overall, but the language-universal phonotactic cue does not, and that their combination results in the most improvement. Not only does this suggest that language-specific constraints can be learned simultaneously with speech segmentation, but it is also consistent with experimental research that shows that there are multiple phonotactic cues helpful to segmentation (e.g. Mattys, Jusczyk, Luce & Morgan, 1999; Mattys & Jusczyk, 2001). This result also compares favorably to other segmentation models (e.g. Brent, 1999; Fleck, 2008; Goldwater, 2007; Johnson & Goldwater, 2009; Venkataraman, 2001) and has implications for how infants learn to segment.
Words in puddles of sound: modelling psycholinguistic effects in speech segmentation
Authors: MONAGHAN PADRAIC , CHRISTIANSEN MORTEN H.
Published: March 2010

There are numerous models of how speech segmentation may proceed in infants acquiring their first language. We present a framework for considering the relative merits and limitations of these various approaches. We then present a model of speech segmentation that aims to reveal important sources of information for speech segmentation, and to capture psycholinguistic constraints on children's language perception. The model constructs a lexicon based on information about utterance boundaries and deduces phonotactic constraints from the discovered lexicon. Compared to other models of speech segmentation, our model performs well in terms of accuracy, computational tractability and the number of components of the model. Finally, our model also reflects the psycholinguistic effects of language learning, in terms of the early advantage for segmentation provided by the child's name, and by revealing the overlap in usefulness of information for segmentation and for grammatical categorization of the language.
Segmenting words from natural speech: subsegmental variation in segmental cues
Authors: RYTTING C. ANTON , BREW CHRIS , FOSLER-LUSSIER ERIC
Published: March 2010

Most computational models of word segmentation are trained and tested on transcripts of speech, rather than the speech itself, and assume that speech is converted into a sequence of symbols prior to word segmentation. We present a way of representing speech corpora that avoids this assumption, and preserves acoustic variation present in speech. We use this new representation to re-evaluate a key computational model of word segmentation. One finding is that high levels of phonetic variability degrade the model's performance. While robustness to phonetic variability may be intrinsically valuable, this finding needs to be complemented by parallel studies of the actual abilities of children to segment phonetically variable speech.
Diarrhoea morbidity and mortality in older children, adolescents, and adults
Authors: WALKER C. L. FISCHER , BLACK R. E.
Published: March 2010

Diarrhoea is a leading cause of morbidity and mortality yet diarrhoea specific incidence and mortality rates for older children, adolescents, and adults have not been systematically calculated for many countries. We conducted a systematic literature review to generate regional incidence rates by age and to summarize diarrhoea specific mortality rates for regions of the world with inadequate vital registration data. Diarrhoea morbidity rates range from 29·9 episodes/100 person-years for adults in the South East Asian region to 88·4 episodes/100 person-years in older children in the Eastern Mediterranean region and have remained unchanged in the last 30 years. Diarrhoea mortality rates decline as the child ages and remain relatively constant during adulthood. These data are critical for improving estimates worldwide and further highlight the need for improved diarrhoea specific morbidity and mortality data in these age groups.
Abnormalities of the major intrathoracic arteries in Turner syndrome as revealed by magnetic resonance imaging
Authors: Mortensen Kristian Havmand , Hjerrild Britta Eilersen , Andersen Niels Holmark , Sørensen Keld Ejvind , Hørlyck Arne , Pedersen Erik Morre , Lundorf Erik , Christiansen Jens Sandahl , Gravholt Claus Højbjerg
Published: March 2010

Background

Ectatic aortopathy and arterial abnormalities cause excess morbidity and mortality in Turner syndrome, where a state of vasculopathy seemingly extends into the major head and neck branch arteries.

Objective

We investigated the prevalence of abnormalities of the major intrathoracic arteries, their interaction with arterial dimensions, and their association with karyotype.

Design

Magnetic resonance imaging scans determined the arterial abnormalities as well as head and neck branch artery and aortic dimensions in 99 adult women with Turner syndrome compared with 33 healthy female controls. Echocardiography determined aortic valve morphology.

Results

In Turner syndrome, the relative risk of any congenital abnormality was 7.7 (p = 0.003) and 6.7 of ascending aortic dilation (p = 0.02). A bovine aortic arch was seen in both Turner syndrome and controls. Other abnormalities were only encountered in Turner syndrome: elongated transverse aortic arch (47%), bicuspid aortic valve (27%), aortic coarctation (13%), aberrant right subclavian artery (8%), and aortic arch hypoplasia (2%). The innominate and left common carotid arteries were enlarged in Turner syndrome (p < 0.001). Significant associations were first, bicuspid aortic valve with aortic coarctation, elongated transverse aortic arch, and ascending aortic dilation; second, aortic coarctation with elongated aortic arch and descending aortic dilation; third, 45,X with aortic coarctation, elongated transverse aortic arch and ascending aortic dilation; and fourth, branch artery dilation with bicuspid aortic valve, aortic coarctation, elongated transverse aortic arch and 45,X.

Conclusion

An increased risk of arterial abnormalities, aortic dilation, and enlargement of the branch arteries was found in Turner syndrome without distinct patterns of co-segregation.
Non-compacted myocardium and foetal left isomerism as a hydrops’ aetiology
Authors: Rocha Ilda J. G. , Nogueira Rosete M. A. N. , Carriço Ana L. C.
Published: March 2010

We present a case report of a pregnant woman with increased risk for trisomy 21 at first-trimester screening, assessed by ultrasonography, that was sent to our hospital. Amniocentesis was performed at 14 weeks and 2 days to obtain foetal karyotype that was normal (46,XX). At 19 weeks and 1 day, foetal hydrops associated with cardiac malformation was detected by routine scan. Foetal echocardiogram revealed a complete auriculoventricular septal defect, non-compacted myocardium, and a bradycardia of 70–90 beats per minute, which lead to the suspicion of left isomerism. Foetal death occurred at 20 weeks and 3 days. Autopsy was consistent with the prenatal diagnosis.
ON THE MEASUREMENT OF TOTAL FACTOR PRODUCTIVITY: A LATENT VARIABLE APPROACH
Authors: Fuentes J. Rodrigo , Morales Marco
Published: March 2010

Despite the important role that total factor productivity (TFP) has played in the growth literature, few attempts have been made to change the methodology to estimate it. This paper proposes a methodology based on a state-space model to estimate TFP and its determinants. With this methodology, it is possible to reduce the measurement of our ignorance. As a by-product, this estimate yields the capital share in output and the long-term growth rate. When applied to Chile, the estimation shows a capital share around 0.5 and long-term growth of TFP around 1%. Capital accumulation tends to explain the growth rate in the fast growth periods under the econometric estimation more than the traditional growth accounting methodology.
HOW SHOULD THE GOVERNMENT ALLOCATE ITS TAX REVENUES BETWEEN PRODUCTIVITY-ENHANCING AND UTILITY-ENHANCING PUBLIC GOODS?
Authors: Economides George , Park Hyun , Philippopoulos Apostolis
Published: March 2010

We present a fairly standard general equilibrium model of endogenous growth with productive and nonproductive public goods and services. The former enhance private productivity and the latter private utility. We study Ramsey second-best optimal policy, where the latter is summarized by the paths of the income tax rate and the allocation of collected tax revenues between productivity-enhancing and utility-enhancing public expenditures. We show that the properties and macroeconomic implications of the second-best optimal policy (a) are different from the benchmark case of the social planner's first-best allocation and (b) depend crucially on whether public goods and services are subject to congestion.
THE BOUNDED FRAGMENT AND HYBRID LOGIC WITH POLYADIC MODALITIES
Authors: HODKINSON IAN
Published: March 2010

We show that the bounded fragment of first-order logic and the hybrid language with ‘downarrow’ and ‘at’ operators are equally expressive even with polyadic modalities, but that their ‘positive’ fragments are equally expressive only for unary modalities.
European‐wide simulations of croplands using an improved terrestrial biosphere model: Phenology and productivity
Authors: Smith P. C. , De Noblet‐Ducoudré N. , Ciais P. , Peylin P. , Viovy N. , Meurdesoif Y. , Bondeau A.
Published: March 2010

Aiming at producing improved estimates of carbon source/sink spatial and interannual patterns across Europe (35% croplands), this work combines the terrestrial biosphere model Organizing Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE), for vegetation productivity, water balance, and soil carbon dynamics, and the generic crop model Simulateur Multidisciplinaire pour les Cultures Standard (STICS), for phenology, irrigation, nitrogen balance, and harvest. The ORCHIDEE‐STICS model, relying on three plant functional types for the representation of temperate agriculture, is evaluated over the last few decades at various spatial and temporal resolutions. The simulated leaf area index seasonal cycle is largely improved relative to the original ORCHIDEE simulating grasslands, and compares favorably with remote‐sensing observations (correlation doubles over Europe). Crop yield is derived from annual net primary productivity and compared with wheat and grain maize harvest data for five European countries. Discrepancies between 30 year mean simulated and reported yields are large in Mediterranean countries. Interannual variability amplitude expressed relative to the mean is reduced toward the observed variability (≈10%) when using ORCHIDEE‐STICS. Overall, this study highlights the importance of accounting for the specific phenologies of crops sown both in winter and in spring and for irrigation applied to spring crops in regional/global models of the terrestrial carbon cycle. Limitations suggest to account for temporal and spatial variability in agricultural practices for further simulation improvement.
Finite‐difference time‐domain modeling of infrasound from pulsating auroras and comparison with recent observations
Authors: de Larquier Sebastien , Pasko Victor P. , Stenbaek‐Nielsen Hans C. , Wilson Charles R. , Olson John V.
Published: March 2010

A FDTD model of infrasound propagation in a realistic atmosphere is used to provide quantitative interpretation of the recently reported infrasound signatures from pulsating aurora. The pressure perturbations observed on the ground are analyzed as a function of energy flux of precipitating auroral electrons and geometry and altitude localization of the source. The results indicate that fluxes on the order of 50 erg/cm2/s are needed to explain pressure waves magnitudes of 0.05 Pa observed on the ground. This energy is unlikely to be provided exclusively by precipitating electrons, and Joule heating associated with the electrojet modulated by the pulsating aurora may be responsible for part of the deposited energy.
Cluster observations of bidirectional beams caused by electron trapping during antiparallel reconnection
Authors: Egedal J. , Lê A. , Katz N. , Chen L.‐J. , Lefebvre B. , Daughton W. , Fazakerley A.
Published: March 2010

So‐called bidirectional electron beams have been observed by a number of spacecraft missions mainly in the inflow of reconnection regions. Here we show that these beam‐like features in the electron distribution function are explained by electron trapping. The trapping is mainly controlled by a positive acceleration potential, Φ∥, which is related to the structure of the parallel electric fields in the vicinity of the reconnection region. Guided by the results of a kinetic simulation, we extend a recent analytical model for the electron distribution function applicable to the inflow region in antiparallel reconnection. The model is successfully compared to data observed by the four Cluster spacecraft inside an active reconnection region. The anisotropy recorded in the electron distributions is consistent with mainly electric trapping of electrons by Φ∥. In the analysis we determine the profiles of Φ∥ along the paths of the Cluster spacecraft during their encounter with a reconnection region. Typical values of eΦ∥ are in excess of 1 keV (much higher than the electron temperature in the ambient lobe plasma) and Φ∥ traps all thermal electrons. This is important for the internal structure of the Hall current system associated with the ion diffusion region because extended trapping significantly alters the electrical and kinematic properties of the electron fluid. Finally, at the boundary between the inflow and exhaust regions the values of eΦ∥ in the inflow region smoothly approach the shoulder energies (up to 15 keV) of the so‐called flat‐top distribution observed in the reconnection exhaust. This suggests that Φ∥ may be important also to the formation of the flat‐top distributions.
Role of oxygen ions in the formation of a bifurcated current sheet in the magnetotail
Authors: Dalena S. , Greco A. , Zimbardo G. , Veltri P.
Published: March 2010

Cluster observations in the near‐Earth magnetotail have shown that sometimes the current sheet is bifurcated, i.e., it is divided in two layers. The influence of magnetic turbulence on ion motion in this region is investigated by numerical simulation, taking into account the presence of both protons and oxygen ions. The magnetotail current sheet is modeled as a magnetic field reversal with a normal magnetic field component Bn, plus a three‐dimensional spectrum of magnetic fluctuations δB, which represents the observed magnetic turbulence. The dawn‐dusk electric field Ey is also included. A test particle simulation is performed using different values of δB, Ey and injecting two different species of particles, O+ ions and protons. O+ ions can support the formation of a double current layer both in the absence and for large values of magnetic fluctuations (δB/B0 = 0.0 and δB/B0 ≥ 0.4, where B0 is the constant magnetic field in the magnetospheric lobes).
Comparison of seasonal changes in fluorescent dissolved organic matter among aquatic lake and stream sites in the Green Lakes Valley
Authors: Miller Matthew P. , McKnight Diane M.
Published: March 2010

The spectral characteristics of whole water dissolved organic matter (DOM) and fulvic acid were studied in samples collected from an alpine lake, a subalpine lake, and a subalpine stream during snowmelt and the summer growing season. Excitation‐emission matrices of whole water DOM and fulvic acid were analyzed by parallel factor analysis (PARAFAC). Allochthonous inputs of terrestrially derived fulvic acid DOM were dominant during snowmelt at the alpine lake, and during both snowmelt and summer at the subalpine sites. At the alpine lake, autochthonous inputs of DOM dominated during the summer phytoplankton bloom, and the spectral characteristics of the whole water DOM diverged from those of the fulvic acid. For example, the quinone‐like fluorophores in whole water DOM at the alpine lake were more oxidized and microbially derived than the fulvic acid fraction during the summer. At the subalpine sites, the seasonal changes in the source and redox state of the quinone‐like fluorophores of the whole water DOM tracked those of the fulvic acid pool. However, at both lake sites there was a greater contribution of amino acid‐like fluorophores in the whole water DOM than the fulvic acid fraction. This trend was not observed at the subalpine stream site. Principal components analysis (PCA) of the PARAFAC components suggests that during snowmelt, the chemical quality of the DOM at the alpine lake was similar to that of the subalpine stream; whereas the alpine site was more similar to the subalpine lake during the summer. Spectral characterization and PCA of the PARAFAC components suggest that nonhumic quinone‐like and amino acid‐like fluorophores were produced in the alpine lake during the summer phytoplankton bloom. Our results show that different types of water bodies produce different seasonal patterns in whole water DOM and fulvic acid quantity and quality.
Information theory–based approach for location of monitoring water level gauges in polders
Authors: Alfonso Leonardo , Lobbrecht Arnold , Price Roland
Published: March 2010

Data collection is a critical activity in the management of water systems because it supports informed decision making. Data are collected by means of monitoring networks in which water level gauges are of particular interest because of their implications for flood management. This paper introduces a number of modifications to previously published methods that use information theory to design hydrological monitoring networks in order to make the methods applicable to the design of water level monitors for highly controlled polder systems. The new contributions include the use of a hydrodynamic model for entropy analysis, the introduction of the quantization concept to filter out noisy time series, and the use of total correlation to evaluate the performance of three different pairwise dependence criteria. The resulting approach, water level monitoring design in polders (WMP), is applied to a polder in the Pijnacker region, Netherlands. Results show that relatively few monitors are adequate to collect the information of a polder area in spite of its large number of target water levels. It is found, in addition, that the directional information transfer DITYX is more effective in finding independent monitors, whereas DITXY is better for locating sets of monitors with high joint information content. WMP proves to be a suitable and simple method as part of the design of monitoring networks for polder systems.
Comment on “Preserving the Boltzmann ensemble in replica-exchange molecular dynamics” [J. Chem. Phys. 129, 164112 (2008)]
Authors: Fukuda Ikuo
Published: March 2010

A brief discussion of the ergodic description of constant temperature molecular dynamics (MD) is provided; the discussion is based on the analysis of criticisms raised in a recent paper [B. Cooke and S. C. Schmidler, J. Chem. Phys.129, 164112 (2008)]. In the paper, the following criticisms relating to the basic concepts of constant temperature MD are made in mathematical manners: (I) the Nosé–Hoover (NH) equation is not measure-preserving; (II) NH system and NH chain system are not ergodic under the Boltzmann measure; and (III) the Nosé Hamiltonian system as well as the Nosé–Poincaré Hamiltonian system is not ergodic. In this comment, I show the necessity for the reconsideration of these criticisms. The NH equation is measure-preserving, where the measure carries the Boltzmann–Gibbs density; this fact provides the compatibility between MD equation and the Boltzmann–Gibbs distribution. The arguments advanced in support of the above criticisms are unsound; ergodicities of those systems are still not theoretically judged. I discuss exact ergodic-theoretical expressions appropriate for constant temperature MD, and explain the reason behind the incorrect recognitions.
The Dirac equation in Kerr–Newman–Ads black hole background
Authors: Belgiorno Francesco , Cacciatori Sergio L.
Published: March 2010

We consider the Dirac equation on the Kerr–Newman–AdS black hole background. We first perform the variable separation for the Dirac equation and define the Hamiltonian operator Ĥ. Then we show that for a massive Dirac field with mass μ≥1/(2l), where l is linked to the cosmological constant Λ by Λ≕−3/l2, essential self-adjointness of Ĥ on C0∞((r+,∞)×S2)4 is obtained even in presence of the boundarylike behavior of infinity in an asymptotically AdS black hole background. Furthermore, qualitative spectral properties of the Hamiltonian are taken into account and in agreement with the existing results concerning the case of stationary axisymmetric asymptotically flat black holes we infer the absence of time-periodic and normalizable solutions of the Dirac equation around the black hole in the nonextremal case.
Complex dynamics of three interacting spheres in a rotating drum
Authors: Davidheiser James E. , Syers Paul , Segrè P. N. , Weeks Eric R.
Published: March 2010

Numerous studies have demonstrated the potential for particles in fluids to exhibit complicated dynamical behavior. In this work, we study a horizontal rotating drum filled with pure glycerol and three large, heavy spheres. The rotation of the drum causes the spheres to cascade and tumble and thus interact with each other. We find several different behaviors of the spheres depending on the drum rotation rate. Simpler states include the spheres remaining well separated, or states where two or all three of the spheres come together and cascade together. We also see two more complex states, where two or three of the spheres move erratically. The main signature of this erratic motion is that pairs of spheres intermittently approach each other (sometimes colliding) and then separate; the time between collisions is variable even for a fixed rotation rate. We characterize these disordered states and find a complex phase space with a rich set of behaviors. This experiment serves as a simple model system to demonstrate complex behavior in simple fluid dynamical systems.
Band gap aligned conducting interface modifier enhances the performance of thermal stable polymer-TiO2 nanorod solar cell
Authors: Huang Yu-Ching , Yen Wei-Che , Liao Yu-Chia , Yu Ya-Chien , Hsu Cheng-Chih , Ho Mei-Lin , Chou Pi-Tai , Su Wei-Fang
Published: March 2010

In this paper, we show that the poly(3-hexyl-thiophene)/TiO2 nanorod hybrid material is more thermally stable than the poly(3-hexyl-thiophene)/[6,6]-phenyl C61-bntyric acid methyl ester (P3HT/PCBM) hybrid material. A metal free conducting interface modifier of oligo-3-hexyl thiophene carboxylic acid (oligo-3HT-COOH) has been synthesized that exhibits aligned band gap for the P3HT/TiO2 hybrid. The conducting modifier shows an increase in power conversion efficiency of 4.8 times over an insulating modifier of oleic acid and 2.2 folds improvement over small molecule modifier of pyridine. These increases are due to a reduced recombination rate (42 μs carrier life time) and fast electron injection time of 0.24 ps. This interface modifier makes thermally stable organic-inorganic hybrid materials useful for fabrication of all solution processable solar cells.
An efficient algorithm for classical density functional theory in three dimensions: Ionic solutions
Authors: Knepley Matthew G. , Karpeev Dmitry A. , Davidovits Seth , Eisenberg Robert S. , Gillespie Dirk
Published: March 2010

Classical density functional theory (DFT) of fluids is a valuable tool to analyze inhomogeneous fluids. However, few numerical solution algorithms for three-dimensional systems exist. Here we present an efficient numerical scheme for fluids of charged, hard spheres that uses O(N log N) operations and O(N) memory, where N is the number of grid points. This system-size scaling is significant because of the very large N required for three-dimensional systems. The algorithm uses fast Fourier transforms (FFTs) to evaluate the convolutions of the DFT Euler–Lagrange equations and Picard (iterative substitution) iteration with line search to solve the equations. The pros and cons of this FFT/Picard technique are compared to those of alternative solution methods that use real-space integration of the convolutions instead of FFTs and Newton iteration instead of Picard. For the hard-sphere DFT, we use fundamental measure theory. For the electrostatic DFT, we present two algorithms. One is for the “bulk-fluid” functional of Rosenfeld [Y. Rosenfeld, J. Chem. Phys. 98, 8126 (1993)] that uses O(N log N) operations. The other is for the “reference fluid density” (RFD) functional [D. Gillespie et al., J. Phys.: Condens. Matter 14, 12129 (2002)]. This functional is significantly more accurate than the bulk-fluid functional, but the RFD algorithm requires O(N2) operations.
Phase stability of carbon clathrates at high pressure
Authors: Wang Jian-Tao , Chen Changfeng , Wang Ding-Sheng , Mizuseki H. , Kawazoe Y.
Published: March 2010

Group-IV element clathrates have attracted considerable interest in recent years. Here, we report an ab initio study on the structural stability of carbon clathrates at high pressure and identify fcc-C136 clathrate as the third most stable carbon phase after cubic diamond and hexagonal graphite. A pressure-induced phase transition is predicted to occur around 17 GPa from hexagonal graphite to fcc-C136, which is more stable than other carbon clathrates such as hex-C40 and sc-C46, and the recently predicted metastable M-carbon up to 26 GPa. Phonon dispersion calculations confirm the dynamic stability of fcc-C136 as well as diamond.
The basic polyhedral clusters, the optimum glass formers, and the composition-structure-property (glass-forming ability) correlation in Cu–Zr metallic glasses
Authors: Sha Z. D. , Xu B. , Shen L. , Zhang A. H. , Feng Y. P. , Li Y.
Published: March 2010

Using the large-scale atomic/molecular massively parallel simulator, chemical short-range order of the Cu–Zr binary system over the three good glass-forming compositional ranges has been investigated. Based on a statistical analysis, a simple route has been developed for broad investigations of the basic polyhedral clusters, optimum glass formers, as well as the composition-structure-property (glass-forming ability) correlation. In addition, topological short-range orders of the basic polyhedral clusters in the three compositional ranges were characterized. Our findings have implications for understanding the nature, forming ability, and properties of metallic glasses.
Spatially resolved measurements of the ferromagnetic phase transition by ac-susceptibility investigations with x-ray photoelectron emission microscope
Authors: Römer F. M. , Kronast F. , Heyne L. , Hassel C. , Banholzer A. , Kläui M. , Meckenstock R. , Lindner J. , Farle M.
Published: March 2010

Spatially resolved ac susceptibility measurements on epitaxial Fe films are performed as a function of temperature using a conventional soft-x-ray photoelectron emission microscope. A magnetic contrast is observed at sample locations where the magnetic film undergoes a para/ferromagnetic phase transition. Due to the wedge structure of the Fe film and the thickness dependence of the Curie temperature the spatial extend of the phase transition region and the correlation length can be estimated.
Vibrational multiconfiguration self-consistent field theory: Implementation and test calculations
Authors: Heislbetz Sandra , Rauhut Guntram
Published: March 2010

A state-specific vibrational multiconfiguration self-consistent field (VMCSCF) approach based on a multimode expansion of the potential energy surface is presented for the accurate calculation of anharmonic vibrational spectra. As a special case of this general approach vibrational complete active space self-consistent field calculations will be discussed. The latter method shows better convergence than the general VMCSCF approach and must be considered the preferred choice within the multiconfigurational framework. Benchmark calculations are provided for a small set of test molecules.
Temperature dependence of spin diffusion length in silicon by Hanle-type spin precession
Authors: Sasaki T. , Oikawa T. , Suzuki T. , Shiraishi M. , Suzuki Y. , Noguchi K.
Published: March 2010

The Hanle-type spin precession method was carried out in association with nonlocal (NL) magnetoresistance measurement using a highly doped (5×1019 cm−3) silicon (Si) channel. The spin diffusion length obtained by the Hanle-method is in good agreement with that of the gap dependence of NL signals. We have evaluated the interface and bulk channel effects separately, and it was demonstrated that the major factor of temperature dependence of NL signals originates from the spin polarization reduction at interface between the tunnel barrier and silicon.
Pump-pump experiment in KH2PO4 crystals: Coupling two different wavelengths to identify the laser-induced damage mechanisms in the nanosecond regime
Authors: Reyné S. , Duchateau G. , Natoli J.-Y. , Lamaignère L.
Published: March 2010

Laser-induced damage experiments based on an original pump-pump set-up have been carried out in the nanosecond regime for KH2PO4 (KDP) crystal. The impact of a simultaneous mixing of 351 nm and 1064 nm pulses has been experimentally studied and compared to a model based on heat transfer, the Mie theory and a Drude model. This study sheds light on the physical processes implied in the KDP laser damage. In particular, a three-photon ionization mechanism is shown to be responsible for laser damage in KDP.
Electrical and mechanical coupling nanodamage in single ZnO nanobelts
Authors: Yang Ya , Qi Junjie , Gu Yousong , Guo Wen , Zhang Yue
Published: March 2010

The electrical and mechanical coupling nanodamage in single ZnO nanobelts has been investigated by using a conductive atomic force microscope. The measured damage threshold voltage was found to decrease from 12 to 6 V as the loading forces were changed from 20 to 180 nN. The mechanism of the decrease in the damage threshold voltages is suggested to be attributed to the strain induced change in electric structures in ZnO.
A Fact is a Fact, but Perception is Reality: Stakeholders' Perceptions and Urban Policies in the Process of Urban Restructuring
Authors: Kokx Anita , van Kempen Ronald
Published: March 2010

Distressed urban areas suffer, by definition, from a number of serious problems. It is often assumed that all relevant stakeholders agree about the character of these problems and the right policy solutions. Reality, however, is more complex. In this paper we investigate how local stakeholders and residents in a Dutch post-WWII neighborhood perceive urban problems and solutions. The findings show the very opposite perceptions about reality and about effective solutions in distressed neighborhoods held by local managers and residents. The main conclusion is that a power-driven narrative of problematic post-WWII neighborhoods within a neoliberal strategic urban agenda has led to a power-driven urban governance arrangement to the exclusion of residents.
Decentralization and Electoral Accountability
Authors: Lago-Peñas Ignacio , Lago-Peñas Santiago
Published: March 2010

On the basis of aggregated and individual-level survey data of national and regional elections in Spain, this paper analyzes how economic voting is impacted by vertical and horizontal dimensions of clarity of responsibility. Our findings suggest that economic voting is enhanced when mechanisms of accountability are simple.
Metal-insulator quantum critical point beneath the high
T
c
superconducting dome
Authors: Sebastian Suchitra E. , Harrison N. , Altarawneh M. M. , Mielke C. H. , Liang Ruixing , Bonn D. A. , Hardy W. N. , Lonzarich G. G.
Published: March 2010

An enduring question in correlated systems concerns whether superconductivity is favored at a quantum critical point (QCP) characterized by a divergent quasiparticle effective mass. Despite such a scenario being widely postulated in high
T
c
cuprates and invoked to explain non-Fermi liquid transport signatures, experimental evidence is lacking for a critical divergence under the superconducting dome. We use ultrastrong magnetic fields to measure quantum oscillations in underdoped YBa
2
Cu
3
O

6+
x

, revealing a dramatic doping-dependent upturn in quasiparticle effective mass at a critical metal-insulator transition beneath the superconducting dome. Given the location of this QCP under a plateau in
T
c
in addition to a postulated QCP at optimal doping, we discuss the intriguing possibility of two intersecting superconducting subdomes, each centered at a critical Fermi surface instability.
The TWEAK–Fn14 system is a critical regulator of denervation-induced skeletal muscle atrophy in mice
Authors: Mittal Ashwani , Bhatnagar Shephali , Kumar Akhilesh , Lach-Trifilieff Estelle , Wauters Sandrine , Li Hong , Makonchuk Denys Y. , Glass David J. , Kumar Ashok
Published: March 2010

Skeletal muscle atrophy occurs in a variety of clinical settings, including cachexia, disuse, and denervation. Inflammatory cytokines have been shown to be mediators of cancer cachexia; however, the role of cytokines in denervation- and immobilization-induced skeletal muscle loss remains unknown. In this study, we demonstrate that a single cytokine, TNF-like weak inducer of apoptosis (TWEAK), mediates skeletal muscle atrophy that occurs under denervation conditions. Transgenic expression of TWEAK induces atrophy, fibrosis, fiber-type switching, and the degradation of muscle proteins. Importantly, genetic ablation of TWEAK decreases the loss of muscle proteins and spared fiber cross-sectional area, muscle mass, and strength after denervation. Expression of the TWEAK receptor Fn14 (fibroblast growth factor–inducible receptor 14) and not the cytokine is significantly increased in muscle upon denervation, demonstrating an unexpected inside-out signaling pathway; the receptor up-regulation allows for TWEAK activation of nuclear factor κB, causing an increase in the expression of the E3 ubiquitin ligase MuRF1. This study reveals a novel mediator of skeletal muscle atrophy and indicates that the TWEAK–Fn14 system is an important target for preventing skeletal muscle wasting.
Fibroblast growth factor receptors 1 and 2 in keratinocytes control the epidermal barrier and cutaneous homeostasis
Authors: Yang Jingxuan , Meyer Michael , Müller Anna-Katharina , Böhm Friederike , Grose Richard , Dauwalder Tina , Verrey Francois , Kopf Manfred , Partanen Juha , Bloch Wilhelm , Ornitz David M. , Werner Sabine
Published: March 2010

Fibroblast growth factors (FGFs) are master regulators of organogenesis and tissue homeostasis. In this study, we used different combinations of FGF receptor (FGFR)-deficient mice to unravel their functions in the skin. Loss of the IIIb splice variants of FGFR1 and FGFR2 in keratinocytes caused progressive loss of skin appendages, cutaneous inflammation, keratinocyte hyperproliferation, and acanthosis. We identified loss of FGF-induced expression of tight junction components with subsequent deficits in epidermal barrier function as the mechanism underlying the progressive inflammatory skin disease. The defective barrier causes activation of keratinocytes and epidermal γδ T cells, which produce interleukin-1 family member 8 and S100A8/A9 proteins. These cytokines initiate an inflammatory response and induce a double paracrine loop through production of keratinocyte mitogens by dermal cells. Our results identify essential roles for FGFs in the regulation of the epidermal barrier and in the prevention of cutaneous inflammation, and highlight the importance of stromal–epithelial interactions in skin homeostasis and disease.
ERO1-β, a pancreas-specific disulfide oxidase, promotes insulin biogenesis and glucose homeostasis
Authors: Zito Ester , Chin King-Tung , Blais Jaime , Harding Heather P. , Ron David
Published: March 2010

Mammals have two genes encoding homologues of the endoplasmic reticulum (ER) disulfide oxidase ERO1 (ER oxidoreductin 1). ERO1-β is greatly enriched in the endocrine pancreas. We report in this study that homozygosity for a disrupting allele of Ero1lb selectively compromises oxidative folding of proinsulin and promotes glucose intolerance in mutant mice. Surprisingly, concomitant disruption of Ero1l, encoding the other ERO1 isoform, ERO1-α, does not exacerbate the ERO1-β deficiency phenotype. Although immunoglobulin-producing cells normally express both isoforms of ERO1, disulfide bond formation and immunoglobulin secretion proceed at nearly normal pace in the double mutant. Moreover, although the more reducing environment of their ER protects cultured ERO1-β knockdown Min6 cells from the toxicity of a misfolding-prone mutant Ins2Akita, the diabetic phenotype and islet destruction promoted by Ins2Akita are enhanced in ERO1-β compound mutant mice. These findings point to an unexpectedly selective function for ERO1-β in oxidative protein folding in insulin-producing cells that is required for glucose homeostasis in vivo.
Clinical Practice Guidelines for Clostridium difficile Infection in Adults: 2010 Update by the Society for Healthcare Epidemiology of America (SHEA) and the Infectious Diseases Society of America (IDSA)
Authors: Cohen Stuart H. , Gerding Dale N. , Johnson Stuart , Kelly Ciaran P. , Loo Vivian G. , McDonald L. Clifford , Pepin Jacques , Wilcox Mark H.
Published: March 2010

Since publication of the Society for Healthcare Epidemiology of America position paper onClostridium difficileinfection in 1995, significant changes have occurred in the epidemiology and treatment of this infection.C. difficileremains the most important cause of healthcare-associated diarrhea and is increasingly important as a community pathogen. A more virulent strain ofC. difficilehas been identified and has been responsible for more-severe cases of disease worldwide. Data reporting the decreased effectiveness of metronidazole in the treatment of severe disease have been published. Despite the increasing quantity of data available, areas of controversy still exist. This guideline updates recommendations regarding epidemiology, diagnosis, treatment, and infection control and environmental management.
Cause and Cancer Epidemiology
Authors: GOODMAN STEVEN N. , SAMET JONATHAN M.
Published: March 2010

This chapter provides an overview of causal inference, focusing on the interpretation of epidemiologic data on cancer risk. It begins with an introduction to the centuries-old discussion on cause and causation and next considers the epidemiologic concept of causation, setting the discussion in the context of current understanding of carcinogenesis as a multistep process. The criteria for causation, often attributed to the British medical statistician Sir Austin Bradford Hill (Hill, 1965) or to the 1964 Report of the U.S. Surgeon General on tobacco (US Department of Health Education and Welfare—DHEW, 1964), have provided a framework for evaluating evidence to judge the causality of associations. These criteria are addressed in depth, and their application is illustrated with the example of smoking, both active and passive, and lung cancer. The chapter concludes with a consideration of emerging issues concerned with causation, including the interpretation of data coming from the new technologies of contemporary “molecular epidemiology” and new approaches to evaluating causation.
Morphologic and Molecular Classification of Human Cancer
Authors: GIORDANO THOMAS J.
Published: March 2010

This chapter provides an overview of the morphologic assessment of cancer along with the progress made to date for select tumor types in the molecular classification revolution. Topics covered include morphologic classification of cancer, current nomenclature of human cancer, molecular methods for tumor classification, tumor-specific signatures and multitumor classifications, and organ-specific morphologic and molecular classification of select tumors.
Molecular and Genetic Events in Neoplastic Transformation
Authors: ERSON AYSE E. , PETTY ELIZABETH M.
Published: March 2010

This chapter illustrates some of the basic molecular and genetic mechanisms that underlie the development of cancer. The chapter is organized into four main sections. The first section examines perspectives on the roles of oncogenes, tumor suppressor genes, and genomic instability genes in the pathogenesis of malignancy. The second section presents the genetic and epigenetic alterations that disrupt normal function of cancer genes. The third section discusses the alteration of cell cycle progression and checkpoint mechanisms relative to their possible contribution to carcinogenesis. The last section summarizes the phenotypic characteristics of cancer cells, including proliferation, apoptosis, angiogenesis, and metastasis as related to specific molecular events.
Risk Assessment of Carcinogenic Hazards
Authors: STAYNER LESLIE T. , BOFFETTA PAOLO , VAINIO HARRI
Published: March 2010

This chapter presents a brief overview of the current concepts, methods, and controversies related to cancer risk assessment with a special emphasis on the role of epidemiologic studies. Topics covered include definition of the risk assessment process, hazard identification, exposure assessment, and risk characterization.
Application of Biomarkers in Cancer Epidemiology
Authors: GARCÍA-CLOSAS MONTSERRAT , VERMEULEN ROEL , SHERMAN MARK E. , MOORE LEE E. , SMITH MARTYN T. , ROTHMAN NATHANIEL
Published: March 2010

Biomarkers are increasingly being incorporated into epidemiologic studies of cancer etiology, often referred to as molecular epidemiology. This chapter focuses on the use of biomarkers in the context of etiologic research. It begins with a discussion of the development and characterization of biomarkers for use in epidemiologic studies, with a particular emphasis on understanding the components of variance and their impact on estimates of disease risk. It then discusses key issues in the use of exposure, intermediate end points, genetic susceptibility, and tumor biomarkers; and reviews the main epidemiologic study designs that use biomarkers. The chapter concludes with comments on collecting and processing biologic samples for use in molecular epidemiology studies.
International Patterns of Cancer Incidence and Mortality
Authors: PARKIN D. MAXWELL , BRAY FREDDIE I.
Published: March 2010

This chapter considers the patterns of cancer mainly with respect to what they tell us of differences in the risk of cancer among populations and the possible explanations for them. Information on the burden of disease has a different, albeit related, use during the planning and monitoring of programs of cancer control. The main role of cancer surveillance in this context lies in the assessment of the current magnitude of the cancer burden and its likely future evolution as well as monitoring the effects of early detection/screening, treatment, and palliative care.
Migrant Studies
Authors: KOLONEL LAURENCE N. , WILKENS LYNNE R.
Published: March 2010

This chapter discusses the contributions of migrant studies to cancer research. Migrant populations have contributed essential information to research on the etiology of cancer. Foremost, they have shown the dominant role of environmental factors in determining cancer risk. Because the direction and magnitude of change in incidence vary by cancer site for each migrant group, these studies support the view that the major risk factors for various cancer sites also differ. In some instances, migrant studies have provided information on critical periods of life when risk factors are most influential. They have also suggested useful etiologic hypotheses, particularly those related to lifestyle, especially diet.
Tobacco
Authors: THUN MICHAEL J. , HENLEY S. JANE
Published: March 2010

This chapter considers the factors that transformed tobacco use from a ceremonial practice in pre-Columbian times to a global epidemic. It discusses the role of nicotine addiction in sustaining and modifying exposure to the carcinogens in tobacco, the cancers caused by various forms of tobacco use, the global burden of tobacco-attributable disease, the extent to which design changes in cigarettes have altered their pathogenicity, the influence of genetic and other factors on susceptibility to addiction or carcinogenesis, and finally the immense opportunities for prevention.
Alcohol
Authors: MARSHALL JAMES R. , FREUDENHEIM JO
Published: March 2010

This chapter begins by summarizing current understanding of the mechanisms by which alcohol might affect cancer risk and then evaluates the molecular genetic factors that appear relevant to alcohol metabolism and hence the impact of alcohol on cancer risk. It briefly reviews the means by which alcohol's effects can be studied and their limitations. The role of alcohol in cancer at major cancer sites is then used to gauge the likely importance of alcohol to cancer risk and prevention. These sites are either ones for which there is a substantial literature linking alcohol to risk, or they are associated with significant morbidity and mortality.