bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Cognitive-Communicative Disorders of Mild Traumatic Brain Injury Sustained in Combat
Authors: Parrish Christine , Roth Carole , Roberts Brooke , Davie Gail
Published: May 2009

Background: Mild traumatic brain injury (mTBI) is recognized as the signature injury of the current conflicts in Iraq and Afghanistan, yet there remains limited understanding of the persisting cognitive deficits of mTBI sustained in combat. Speech-language pathologists (SLPs) have traditionally been responsible for evaluating and treating the cognitive-communication disorders following severe brain injuries. The evaluation instruments historically used are insensitive to the subtle deficits found in individuals with mTBI.

Objectives: Based on the limited literature and clinical evidence describing traditional and current tests for measuring cognitive-communication deficits (CCD) of TBI, the strengths and weaknesses of the instruments are discussed relative to their use with mTBI. It is necessary to understand the nature and severity of CCD associated with mTBI for treatment planning and goal setting. Yet, the complexity of mTBI sustained in combat, which often co-occurs with PTSD and other psychological health and physiological issues, creates a clinical challenge for speech-language pathologists worldwide. The purpose of the paper is to explore methods for substantiating the nature and severity of CCD described by service members returning from combat.

Methods: To better understand the nature of the functional cognitive-communication deficits described by service members returning from combat, a patient questionnaire and a test protocol were designed and administered to over 200 patients. Preliminary impressions are described addressing the nature of the deficits and the challenges faced in differentiating the etiologies of the CCD.

Conclusions: Speech-language pathologists are challenged with evaluating, diagnosing, and treating the cognitive-communication deficits of mTBI resulting from combat-related injuries. Assessments that are sensitive to the functional deficits of mTBI are recommended. An interdisciplinary rehabilitation model is essential for differentially diagnosing the consequences of mTBI, PTSD, and other psychological and physical health concerns.
Combined effect of tight-focusing and frequency-chirping on laser acceleration of an electron in vacuum
Authors: Gupta Devki Nandan , Jang Hyo Jae , Suk Hyyong
Published: May 2009

The investigation [Gupta et al., Appl. Phys. Lett. 91, 211101 (2007)] for electron acceleration by a tightly focused laser beam is revisited by including the effect of laser frequency chirping. The frequency chirping plays an important role to enhance the electron energy if the laser is tightly focused. Due to the combined effect of frequency chirping and tight focusing of a laser beam, an electron can be accelerated for a longer time in vacuum. As a result, from the proposed investigation, the electron energy gain during the laser acceleration is found to be considerably higher.
Modulated transverse off-plane dust-lattice wave packets in hexagonal two-dimensional dusty plasma crystals
Authors: Farokhi B. , Shahmansouri M. , Kourakis I.
Published: May 2009

The propagation of nonlinear dust-lattice waves in a two-dimensional hexagonal crystal is investigated. Transverse (off-plane) dust grain oscillatory motion is considered in the form of a backward propagating wave packet whose linear and nonlinear characteristics are investigated. An evolution equation is obtained for the slowly varying amplitude of the first (fundamental) harmonic by making use of a two-dimensional lattice multiple scales technique. An analysis based on the continuum approximation (spatially extended excitations compared to the lattice spacing) shows that wave packets will be modulationally stable and that dark-type envelope solitons (density holes) may occur in the long wavelength region. Evidence is provided of modulational instability and of the occurrence of bright-type envelopes (pulses) at shorter wavelengths. The role of second neighbor interactions is also investigated and is shown to be rather weak in determining the modulational stability region. The effect of dissipation, assumed negligible in the algebra throughout the article, is briefly discussed.
Proton diffusion pathways and rates in Y-doped BaZrO3 solid oxide electrolyte from quantum mechanics
Authors: Merinov Boris , Goddard William
Published: May 2009

We carried out quantum mechanical calculations (Perdew-Becke-Ernzerhof flavor of density functional theory) on 12.5% Y-doped BaZrO3 (BYZ) periodic structures to obtain energy barriers for intraoctahedral and interoctahedral proton transfers. We find activation energy (Ea) values of 0.48 and 0.49 eV for the intraoctahedral proton transfers on O–O edges (2.58 and 2.59 Å) of ZrO6 and YO6 octahedra, respectively, and Ea=0.41 eV for the interoctahedral proton transfer at O–O separation of 2.54 Å. These results indicate that both the interoctahedral and intraoctahedral proton transfers are important in the BYZ electrolyte. Indeed, the calculated values bracket the experimental value of Ea=0.44 eV. Based on the results obtained, the atomic level proton diffusion mechanism and possible proton diffusion pathways have been proposed for the BYZ electrolyte. The thermal librations of BO6 octahedra and uncorrelated thermal vibrations of the two oxygen atoms participating in the hydrogen bond lead to a somewhat chaotic fluctuation in the distances between the O atoms involved in the hydrogen bonding. Such fluctuations affect the barriers and at certain O–O distances allow the hydrogen atoms to move within the hydrogen bonds from one potential minimum to the other and between the hydrogen bonds. Concertation of these intra- and inter-H-bond motions results in continuous proton diffusion pathways. Continuity of proton diffusion pathways is an essential condition for fast proton transport.
Valence and inner-valence shell dissociative photoionization of CO in the 26–33 eV range. I. Ion-electron kinetic energy correlation and laboratory frame photoemission
Authors: Lebech M. , Houver J. C. , Dowek D.
Published: May 2009

The (VA+, Ve, ê) vector correlation method, combining imaging and time-of-flight resolved electron-ion coincidence techniques, is used to probe dissociative photoionization (DPI) of CO induced by vacuum ultra violet linearly or circularly polarized synchrotron radiation in the 26–33 eV photon excitation energy range. It provides original information about both the photoionization dynamics of the CO molecule and the dissociation dynamics of the CO+ molecular ions. The explored region corresponds to valence and inner-valence CO+ ionic states, which involve doubly or multiply excited electronic configurations. In this paper I we identify up to 17 DPI reaction pathways by the position of the intermediate CO+ molecular states in the Franck–Condon region and the (C++O) or (O++C) dissociation limits to which they correlate. For these processes we report the laboratory frame βC+/O+ and βe asymmetry parameters as well as the relative branching ratios in selected binding energy bands. The I(χ,θe,φe) molecular frame photoelectron angular distributions for selected PI processes will be reported in a companion paper II and compared with multichannel Schwinger configuration interaction ab initio calculations of these observables.
Size and surface orientation effects on thermal expansion coefficient of one-dimensional silicon nanostructures
Authors: Zhao H. , Aluru N. R.
Published: May 2009

We perform classical molecular dynamics simulations based on the Tersoff interatomic potential to investigate the size and surface orientation dependence of lattice constant and thermal expansion coefficient of one-dimensional silicon nanostructures. Three different surface orientations of silicon are considered, i.e., Si(110), Si(111), and Si(100) with 2×1 reconstruction. For each surface orientation, we investigate nanostructures with thicknesses ranging from 0.3 to 5.0 nm. We compute the vibrational amplitude of surface atoms, lattice constant, and thermal expansion coefficient as a function of size and temperature, and compare them for different surface orientations. An analytical expression is developed to compute the variation of the thermal expansion coefficient with size of the nanostructure.
Improvement in the determination by 1/f noise measurements of the interface state distribution in polysilicon thin film transistors in relation with the compensation law of Meyer Neldel
Authors: Pichon L. , Boukhenoufa A. , Cretu B. , Rogel R.
Published: May 2009

Low-frequency (1/f) noise is studied in N-channel furnace solid phase crystallized (FSPC) and in laser solid phase crystallized (LSPC) polysilicon thin film transistors (TFTs) biased from weak to strong inversion. Noise analysis is supported by the theory of charge carrier trapping/detrapping at the interface tunneling into gate oxide traps. The distribution of interface trap states (NT) is deduced from the number of carriers trapped into the oxide. Noise measurements for devices biased from weak to moderate inversion allow the determination of the distribution of deep level trap states associated with dangling bond-type defects (NTdb), whereas measurements from moderate to strong inversion give the distribution of shallow level trap states (NTts) associated with strained bond defects. The noise analysis clearly shows that the slope of both exponential distributions equals to the reverse of the Meyer Neldel energy EMN (0.035 and 0.055 eV for FSPC and LSPC TFTs, respectively). For LSPC devices the resulting distribution of interface states (NT=NTdb+NTts) is one decade lower and it is attributed to the effects of the laser annealing on the active layer crystal quality.
Restoration of terahertz signals distorted by atmospheric water vapor absorption
Authors: Wang Yingxin , Chen Zhiqiang , Zhao Ziran , Zhang Li , Kang Kejun , Zhang Yan
Published: May 2009

Terahertz spectroscopic measurements under ordinary atmospheric conditions may suffer interferences from water vapor absorption in the ambient air. A manifold of narrow absorption lines appears in the terahertz spectrum at particular frequencies corresponding to the pure rotational transitions of water molecules. For real-world data, such effect results in unwanted spectral artifacts in the deconvolved spectrum of the examined sample and thus complicates its frequency-dependent characterization. In this paper we use a signal postprocessing algorithm consisting of line shape fitting and spectral subtraction procedures to eliminate the water lines. Restoration of terahertz signals from simulated data and low-humidity measurements is first demonstrated to validate the algorithm. Furthermore, to overcome the difficulty of eliminating strong lines which lead to possible excessive absorption under high-humidity environment, we propose to modify the objective function in spectral subtraction by smoothing the residual spectrum to get acceptable performance.
Curved electronic pixel arrays using a cut and bend approach
Authors: Street R. A. , Wong W. S. , Lujan R.
Published: May 2009

Electronics fabricated on a flat flexible substrate can readily be bent into a cylinder or cone but not into a general three-dimensional curved shape. A solution to this problem is described, in which an electronic device is first fabricated on a flat surface and then shaped to a good approximation of any smooth curved shape, using a cut and bend approach, following the design principles of a geodesic dome. A small additional strain allows the surface to conform to an exact spherical cap. The array is fabricated with amorphous silicon thin film transistors and photodiodes on a plastic substrate.
The role of He in enhancing the intensity and lifetime of H and D emissions from laser-induced atmospheric-pressure plasma
Authors: Kurniawan Koo Hendrik , Lie Tjung Jie , Suliyanti Maria Margaretha , Hedwig Rinda , Pardede Marincan , Ramli Muliadi , Niki Hideaki , Abdulmadjid Syahrun Nur , Idris Nasrullah , Lahna Kurnia , Kusumoto Yoshihumi , Kagawa Kiichiro , Tjia May On
Published: May 2009

A series of measurements have been performed on the time dependences of the intensities of helium, hydrogen, and deuterium emission lines from the corresponding laser-induced helium plasma at atmospheric pressure for two different He flow rates. The prolonged Hα and Hβ emissions along with their constant intensity ratio over a relatively extended period indicate the need to provide an alternative excitation mechanism other than the well-known thermal excitation process in a hot plasma. This additional excitation mechanism is also related to the metastable excited state of a He atom as indicated by the similar characteristics of the observed time dependence of the emission intensities. The enhanced intensity and lifetime of He emission at a high He flow rate was explained in terms of the collision-induced increase in the number of He atoms excited to above the 2 S10 metastable state, which was also responsible for the delayed excitation of H and D atoms via an energy transfer mechanism involving a Penning-like chemi-ionization process. Finally, the benefits of He-assisted delayed excitation of H and D atoms and the aforementioned enhanced intensity and lifetime at a high He flow rate were demonstrated by the achievement of clearly resolved Hα and Dα emission lines.
High rate synthesis of crystalline silicon films from SiH4+He using high density microwave plasma
Authors: Jia Haijun , Kondo Michio
Published: May 2009

By using a high density microwave-induced plasma source, depositions of crystalline silicon films from SiH4+He mixture are investigated systematically. Microwave power and SiH4 flow rate are used as the variable deposition parameters. Results demonstrate that film deposition rate increases with increasing both the microwave power and the SiH4 flow rate. While film crystallinity promotes with increasing the microwave power but degrades with increasing the SiH4 flow rate. After optimizing the film deposition conditions, highly crystallized Si films are deposited at a rate higher than 1000 nm/s. Promotion of the dissociation efficiency of source gases and enhancement in the diffusion length of film precursors on growing surface are suggested to be main factors responsible for the simultaneous achievements of the high deposition rate and the high film crystallinity. Mechanisms under these phenomena are discussed in detail.
Absolute measurement of the nonlinear refractive indices of reference materials
Authors: Boudebs Georges , Fedus Kamil
Published: May 2009

We report absolute measurements of the nonlinear refractive index on carbon disulfide (CS2) and fused silica. These materials are commonly used as standard references in nonlinear optical experiments. To obtain more accurate values than those usually used, we have combined the z-scan method inside a 4-f imaging system (in order to analyze the spatial distortion of the diffracted pump beam) with the “Kerr shutter” experiment (to evaluate the temporal pulse width durations for three different wavelengths such as 1064, 532, and 355 nm). We obtained surprisingly n2 values one order of magnitude less than the one usually taken into account in the picosecond regime and a more significant dispersion of the nonlinear refraction index. Experimental and simulated Z-scan transmittance profiles as well as acquired autocorrelation functions in the Kerr-gating experiments are presented here in order to validate our measurements.
Method of descent for integrable lattices
Authors: Bogoyavlensky Oleg
Published: May 2009

A method of descent for constructing integrable Hamiltonian systems is introduced. The derived periodic and nonperiodic lattices possess Lax representations with spectral parameter and have plenty of first integrals. Examples of Liouville-integrable four-dimensional Hamiltonian Lotka–Volterra systems are presented.
Three-dimensional solutions of supersymmetrical intertwining relations and pairs of isospectral Hamiltonians
Authors: Cannata F. , Ioffe M. V. , Nishnianidze D. N.
Published: May 2009

The general solution of supersymmetrical intertwining relations for three-dimensional Schrödinger operators is built using the class of second order supercharges with nondegenerate constant metric. This solution includes several models with arbitrary parameters. We are interested only in quantum systems which are not amenable to separation of variables, i.e., cannot be reduced to lower dimensional problems. All constructed Hamiltonians are partially integrable—each of them commutes with a symmetry operator of fourth order in momenta. The same models can be considered also for complex values of parameters leading to a class of non-Hermitian isospectral Hamiltonians.
Van der Waals model for phase transitions in thermoresponsive surface films
Authors: McCoy John D. , Curro John G.
Published: May 2009

Phase transitions in polymeric surface films are studied with a simple model based on the van der Waals equation of state. Each chain is modeled by a single bead attached to the surface by an entropic-Hooke’s law spring. The surface coverage is controlled by adjusting the chemical potential, and the equilibrium density profile is calculated with density functional theory. The interesting feature of this model is the multivalued nature of the density profile seen at low temperature. This van der Waals loop behavior is resolved with a Maxwell construction between a high-density phase near the wall and a low-density phase in a “vertical” phase transition. Signatures of the phase transition in experimentally measurable quantities are then found. Numerical calculations are presented for isotherms of surface pressure, for the Poisson ratio, and for the swelling ratio.
On the accurate calculation of polarizabilities and second hyperpolarizabilities of polyacetylene oligomer chains using the CAM-B3LYP density functional
Authors: Limacher Peter A. , Mikkelsen Kurt V. , Lüthi Hans Peter
Published: May 2009

The polarizability and second hyperpolarizability of polyacetylene oligomer chains of increasing size up to C24H26 were investigated by means of the Coulomb-attenuating method (CAM-B3LYP) using response theory. It was found that this long-range corrected density functional removes to large parts the overestimation observed for standard methods and in many cases provides results close to those of coupled cluster calculations. A direct comparison to experimentally observed dynamic hyperpolarizabilities is made to estimate the accuracy of the method. A basis set study revealed a noticeable contribution of diffuse orbitals to the hyperpolarizability also for larger oligomers. Furthermore, CAM-B3LYP is also confirmed to provide molecular geometries close to experimentally observed structures, especially for longer chain lengths.
Transition into a gapless state and concentration anomalies in the properties of Bi1−xSbx solid solutions
Authors: Rogacheva E. I. , Drozdova A. A. , Nashchekina O. N. , Dresselhaus M. S. , Dresselhaus G.
Published: May 2009

For Bi1−xSbx solid solutions (x=0.01–0.05), the dependences of the electrical conductivity, Hall coefficient, charge carrier mobility, magnetoresistance, Seebeck coefficient, and microhardness on the Sb concentration have been obtained in the temperature range of 77–300K. In the isotherms of these properties, distinct extrema or inflection points have been observed in the range of x=0.025–0.035. The presence of these concentration anomalies is attributed to the critical phenomena, which accompany the transition into a gapless state under increasing Sb concentration.
Enhanced sampling in generalized ensemble with large gap of sampling parameter: Case study in temperature space random walk
Authors: Zhang Cheng , Ma Jianpeng
Published: May 2009

We present an efficient sampling method for computing a partition function and accelerating configuration sampling. The method performs a random walk in the λ space, with λ being any thermodynamic variable that characterizes a canonical ensemble such as the reciprocal temperature β or any variable that the Hamiltonian depends on. The partition function is determined by minimizing the difference of the thermal conjugates of λ (the energy in the case of λ=β), defined as the difference between the value from the dynamically updated derivatives of the partition function and the value directly measured from simulation. Higher-order derivatives of the partition function are included to enhance the Brownian motion in the λ space. The method is much less sensitive to the system size, and to the size of λ window than other methods. On the two dimensional Ising model, it is shown that the method asymptotically converges the partition function, and the error of the logarithm of the partition function is much smaller than the algorithm using the Wang–Landau recursive scheme. The method is also applied to off-lattice model proteins, the AB models, in which cases many low energy states are found in different models.
Localized electronic states induced by defects and possible origin of ferroelectricity in strontium titanate thin films
Authors: Kim Y. S. , Kim J. , Moon S. J. , Choi W. S. , Chang Y. J. , Yoon J.-G. , Yu J. , Chung J.-S. , Noh T. W.
Published: May 2009

Several defect configurations including oxygen vacancies have been investigated as possible origins of the reported room-temperature ferroelectricity of strontium titanate (STO) thin films [Y. S. Kim et al., Appl. Phys. Lett. 91, 042908 (2007)]. First-principles calculations revealed that the Sr–O–O vacancy complexes create deep localized states in the band gap of SrTiO3 without affecting its insulating property. These results are consistent with electronic structural changes determined from optical transmission and x-ray absorption measurements. Our work suggests importance of oxygen vacancies and their complexes in understanding of electronic properties of perovskite oxide thin films, including STO.
Improved thermoelectric properties of Mg2SixGeySn1−x−y nanoparticle-in-alloy materials
Authors: Wang S. , Mingo N.
Published: May 2009

We theoretically find that introducing nanoparticles into Mg2SixGeySn1−x−y alloys considerably improves their thermoelectric figure of merit (ZT). We have computed the thermal conductivity versus nanoparticle size of this class of nanocomposites for nine different material types at various temperatures. We provide validity ranges of nanoparticle concentration that will not reduce the thermoelectric power factor, but will considerably decrease the thermal conductivity. ZT enhancements of two times the alloy values are within reach. In particular, n-type Mg2Si0.4Sn0.6 with Mg2Si or Mg2Ge nanoparticles stand out as one of the best materials for intermediate temperature (800 K) applications, providing a good nontoxic alternative to PbTe.
Relativistic plasma shutter for ultraintense laser pulses
Authors: Reed Stephen A. , Matsuoka Takeshi , Bulanov Stepan , Tampo Motonobu , Chvykov Vladimir , Kalintchenko Galina , Rousseau Pascal , Yanovsky Victor , Kodama Ryousuke , Litzenberg Dale W. , Krushelnick Karl , Maksimchuk Anatoly
Published: May 2009

A relativistic plasma shutter technique is proposed and tested to remove the sub-100 ps pedestal of a high-intensity laser pulse. The shutter is an ultrathin foil placed before the target of interest. As the leading edge of the laser ionizes the shutter material it will expand into a relativistically underdense plasma allowing for the peak pulse to propagate through while rejecting the low intensity pedestal. An increase in the laser temporal contrast is demonstrated by measuring characteristic signatures in the accelerated proton spectra and directionality from the interaction of 30 TW pulses with ultrathin foils along with supporting hydrodynamic and particle-in-cell simulations.
Measuring spin diffusion of electrons in bulk n-GaAs using circularly dichromatic absorption difference spectroscopy of spin gratings
Authors: Yu Hua-Liang , Zhang Xiu-Min , Wang Peng-Fei , Ni Hai-Qiao , Niu Zhi-Chuan , Lai Tianshu
Published: May 2009

Circular dichromatic absorption difference spectroscopy is developed to measure the spin diffusion dynamics of electrons in bulk n-GaAs. This spectroscopy has higher detection sensitivity over homodyne detection of spin-grating-diffracted signal. A model to describe circular dichromatic absorption difference signal is derived and used to fit experimental signal to retrieve decaying rate of spin gratings. A spin diffusion constant of Ds=201±25 cm2/s for bulk n-GaAs has been measured at room temperature using this technique and is close to electron diffusion constant (Dc), which is much different from the case in GaAs quantum wells where Ds is markedly less than Dc.
Ionospheric chemistry: Theoretical treatment of ONOO+ and of NO3+
Authors: Ndome H. , Hochlaf M.
Published: May 2009

In light of accurate ab initio calculations, we discuss the charge transfer, vibrational and electronic de-excitations between O2/O2++NO+/NO and O/O++NO2+/NO2 through the formation and decomposition of NO3+ and ONOO+. For that purpose, we generated the potentials of the electronic ground and excited states of the colliding and molecular species involved in these reactions. We used configuration interaction methods and a large basis set. We predict multistep pathways, which involve both the long range and the molecular regions of the potential energy surfaces of the electronic states of the stable isomers of NO3+ and those of the weakly bound charge transfer complex ONOO+. The couplings between these electronic states such as vibronic, Renner–Teller, Jahn–Teller, and spin orbit are believed to play crucial roles during these important ionospheric ion-molecule reactions.
Squaring cooperative binding circles
Authors: Deutman Alexander B. C. , Monnereau Cyrille , Moalin Mohamed , Coumans Ruud G. E. , Veling Nico , Coenen Michiel , Smits Jan M. M. , de Gelder René , Elemans Johannes A. A. W. , Ercolani Gianfranco , Nolte Roeland J. M. , Rowan Alan E.
Published: May 2009

The cooperative binding effects of viologens and pyridines to a synthetic bivalent porphyrin receptor are used as a model system to study how the magnitudes of these effects relate to the experimentally obtained values. The full thermodynamic and kinetic circles concerning both activation and inhibition of the cage of the receptor for the binding of viologens were measured and evaluated. The results strongly emphasize the apparent character of measured binding and rate constants, in which the fractional saturation of receptors with other guests is linearly expressed in these constants. The presented method can be used as a simple tool to better analyze and comprehend the experimentally observed kinetics and thermodynamics of natural and artificial cooperative systems.
Contrasting concepts of learning and contrasting research methodologies: Affinities and bias
Authors: Hodkinson Phil , Macleod Flora
Published: May 2009

This paper analyses the conceptual significance of different methods of researching learning. Based largely upon our own experiences, we briefly compare the use of mini‐ethnography, life history, cross‐sectional surveys and existing panel survey data. We argue that there are strong affinities between each of these methods and significantly different ways of understanding the nature of learning: mini‐ethnographies with learning as participation, life history with learning as construction and both types of survey with learning as acquisition. Three things follow. The first is that decisions about how to research learning are related to decisions about how to conceptualise and theorise learning. The second is that there is no foolproof empirical way to adjudicate between different conceptualisations of learning, though empirical evidence can and should play a significant part in informing such decisions. The third is that though mixing methods (including mixing more than one different qualitative approach) can bring advantages, the integration of the findings of mixed methods in relation to learning requires careful and sometimes difficult conceptual work.
Tripping, slipping and losing the way: Moving beyond methodological difficulties in social research
Authors: Pirrie Anne , Macleod Gale
Published: May 2009

This article is intended as a contribution to the debate on the epistemology of educational research. It is as much concerned with research as a social process as it is with the process of social research. The authors draw upon ways of walking, discussions of embodiment, place and materiality, and their analogues in relation to the processes of social research in order to explore alternative ways of knowing, and to explore what happens when accounts of the difficulties in conducting research are generally suppressed in sanitised reports of research findings. The distinctions between ‘occupant’ and ‘inhabitant’ knowledge, and between wayfaring and travelling betoken radically different conceptions of applied research in the social sciences. The authors explore the potential of anthropological and literary metaphors to explain the methodological challenges encountered during a specific research project: a three‐year study of ‘routes, destinations and outcomes’ for a group of young people excluded from special schools and Pupil Referral Units, funded by the Department for Children, Schools and Families.
Building a Workforce Development System as an Economic Development Strategy: Lessons from US Programs
Authors: Garmise Shari
Published: May 2009

In the knowledge economy, the economic prosperity of places is increasingly tied to the talents of its people. Therefore, many cities and regions have made the attraction and retention of skilled people a core economic development strategy. This article argues that a better strategy is actually to increase the overall pool of talent available, and to do so means rethinking, and investing in, the workforce system. Once the literature and theory has been reviewed, the second half of the article mines multiple US case studies for useful lessons on how workforce systems can be developed and better aligned to economic development.
Disability, Health and the Labour Market: Evidence from the Welsh Health Survey
Authors: Jones Melanie K. , Latreille Paul L.
Published: May 2009

This study uses data from the Welsh Health Survey to examine issues of disability/health measurement and its impact on labour market outcomes. The data suggest that self-reported disability, general health and summary composite measures of physical and mental health are broadly consistent both in measurement and predictions for labour market outcomes. This consistency in measurement is also demonstrated at the local level but the employment disadvantage associated with disability is found to vary considerably within Wales.
Triple Crisis in Belgium
Authors: Aernoudt Rudy
Published: May 2009

Belgium is facing a triple crisis. This could create a valuable opportunity to encourage the country to make some vital structural reforms that would be completely off the policy agenda in quieter times.
Misplaced Expectations? The Experience of Applied Local Economic Development in Post-Apartheid South Africa
Authors: Nel Etienne , Binns Tony , Bek David
Published: May 2009

A hallmark of post-apartheid South Africa has been the introduction of bold and innovative policy in areas ranging from the national Constitution to resource management policy. In line with this approach, there has been a clear commitment to principles of decentralization and participatory development, with Local Economic Development (LED) featuring prominently in national, provincial and local government pronouncements and planning. Despite considerable policy and funding support for LED, results at best can be described as only modest. This paper critically reflects on the importance attached to LED in South Africa, what has been attempted over the last decade, and the various reasons that might explain the limitations experienced with applied LED, including those that are inherent in the nature of LED and those that can be attributed to local factors. The paper draws upon field-based research undertaken over more than a decade and the findings of a major study undertaken by an international development finance organization. The paper raises challenging questions about the nature, focus and potential of LED as an appropriate development intervention.
Effective Communication Only Part of the Strategy Needed to Promote Help-Seeking of Young People with Mental Health Problems
Authors: Phillipson Lyn , Jones Sandra C. , Wiese Elizabeth
Published: May 2009

Formative research was undertaken in the Illawarra region of New South Wales (south of Sydney, Australia) to identify local communication strategies to influence the help-seeking behavior of young people in relation to a new youth-focused general practice (or physician) led mental health service. Research with the target market (12–25years) revealed the need for a local campaign to address the stigma associated with the use of mental health services and the need to emphasize the central role of the general practitioner or physician to the service. The results also indicated that any overarching campaign should be complemented by segment-specific strategies which tailor not only communication variables and channels to reach different market segments, but also consider varying aspects of the product or service to reach a broad cross-section of the target group.
Short article: Age and synchrony effects in visuospatial working memory
Authors: Rowe Gillian , Hasher Lynn , Turcotte Josée
Published: May 2009

Younger and older adults were administered a computerized version of the Corsi Block visuospatial working memory (VSWM) span task at either their peak or off-peak time of day and in either a high-interference (ascending order of administration, starting with short lists first) or low-interference (descending order, starting with longest lists first) format. Young adults’ span scores were highest in the ascending format. By contrast, older adults performed better in the low-interference format, replicating findings with verbal memory span studies. Although both age groups benefited from being tested at their peak time, the advantage was far greater for older adults, but only in the low-interference format; their scores on the high-interference format were not helped by peak-time testing. These findings are consistent with the suggestion that young adults’ performance on span tasks is influenced by practice and strategies, but the performance of older adults is heavily influenced by interference—which is best controlled at peak times of day. Our findings suggest that both time of testing and interference play critical roles in determining age differences in VSWM span, and both a reduction in interference and peak-time testing may be necessary to optimize older adults’ performance and to maximize the reduction in age differences.
Misdirection, attention and awareness: Inattentional blindness reveals temporal relationship between eye movements and visual awareness
Authors: Kuhn Gustav , Findlay John M.
Published: May 2009

We designed a magic trick that could be used to investigate how misdirection can prevent people from perceiving a visually salient event, thus offering a novel paradigm to examine inattentional blindness. We demonstrate that participants’ verbal reports reflect what they saw rather than inferences about how they thought the trick was done and thus provide a reliable index of conscious perception. Eye movements revealed that for a subset of participants their conscious perception was not related to where they were looking at the time of the event and thus demonstrate how overt and covert attention can be spatially dissociated. However, detection of the event resulted in rapid shifts of eye movements towards the detected event, thus indicating a strong temporal link between overt and covert attention, and that covert attention can be allocated at least 2 or 3 saccade targets ahead of where people are fixating.
Relaxed MHD states of a multiple region plasma
Authors: Hole M.J. , Mills R. , Hudson S. R. , Dewar R.L.
Published: May 2009

We calculate the stability of a multiple relaxation region MHD (MRXMHD) plasma, or stepped-Beltrami plasma, using both variational and tearing mode treatments. The configuration studied is a periodic cylinder. In the variational treatment, the problem reduces to an eigenvalue problem for the interface displacements. For the tearing mode treatment, analytic expressions for the tearing mode stability parameter Δ′, being the jump in the logarithmic derivative in the helical flux across the resonant surface, are found. The stability of these treatments is compared for m = 1 displacements of an illustrative reverse field pinch-like configuration, comprising two distinct plasma regions. For pressureless configurations, we find the marginal stability conclusions of each treatment to be identical, confirming the analytical results in the literature. The tearing mode treatment also resolves ideal MHD unstable solutions for which Δ′ → ∞: these correspond to displacement of a resonant interface. Wall stabilization scans resolve the internal and external ideal kink. Scans with increasing pressure are also performed: these indicate that both variational and tearing mode treatments have the same stability trends with β, and show destabilization in configurations with increasing core pressure. Combined, our results suggest that variational stability of MRXMHD configurations is sufficient for both ideal and tearing (Δ′ < 0) stability. Such configurations, and their stability properties, are of emerging importance in the quest to find mathematically rigorous solutions of ideal MHD force balance in 3D geometry.
Online databases and computational tools for non-LTE spectroscopy
Authors: Ralchenko Yuri
Published: May 2009

Atomic structure and collisional databases have been actively developed since the early era of the World Wide Web. It is only recently that a number of plasma kinetics databases have become available for the physics community. Moreover, it is now possible to perform advanced online collisional–radiative calculations for plasmas far from local thermodynamic equilibrium (LTE). We describe several online databases and tools that can be used in non-LTE research. Special attention is given to the new databases recently developed at the National Institute of Standards and Technology.
Commutator maps, measure preservation, and 𝑇-systems
Authors: Garion Shelly , Shalev Aner
Published: May 2009

Let

G
G

be a finite simple group. We show that the commutator map

α
:
G
×
G
→
G

\alpha :G \times G \rightarrow G

is almost equidistributed as

|

G

|

→
∞

|G| \rightarrow \infty

. This somewhat surprising result has many applications. It shows that a for a subset

X
⊆
G

X \subseteq G

we have
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="alpha Superscript negative 1 Baseline left-parenthesis upper X right-parenthesis slash StartAbsoluteValue upper G EndAbsoluteValue squared equals StartAbsoluteValue upper X EndAbsoluteValue slash StartAbsoluteValue upper G EndAbsoluteValue plus o left-parenthesis 1 right-parenthesis">

α

−
1

(
X
)

/

|

G

|

2

=

|

X

|

/

|

G

|

+
o
(
1
)

\alpha ^{-1}(X)/|G|^2 = |X|/|G| + o(1)

, namely

α
\alpha

is almost measure preserving. From this we deduce that almost all elements

g
∈
G

g \in G

can be expressed as commutators

g
=
[
x
,
y
]

g = [x,y]

where

x
,
y

x,y

generate

G
G

.

This enables us to solve some open problems regarding

T
T

-systems and the Product Replacement Algorithm (PRA) graph. We show that the number of

T
T

-systems in

G
G

with two generators tends to infinity as

|

G

|

→
∞

|G| \rightarrow \infty

. This settles a conjecture of Guralnick and Pak. A similar result follows for the number of connected components of the PRA graph of

G
G

with two generators.

Some of our results apply for more general finite groups and more general word maps.

Our methods are based on representation theory, combining classical character theory with recent results on character degrees and values in finite simple groups. In particular the so called Witten zeta function
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="zeta Superscript upper G Baseline left-parenthesis s right-parenthesis equals sigma-summation Underscript chi element-of upper I r r left-parenthesis upper G right-parenthesis Endscripts chi left-parenthesis 1 right-parenthesis Superscript negative s">

ζ
G

(
s
)
=

∑

χ
∈
Irr
⁡
(
G
)

χ
(
1

)

−
s

\zeta ^G(s) = \sum _{\chi \in \operatorname {Irr}(G)}\chi (1)^{-s}

plays a key role in the proofs.
Elliptic equations with critical growth and a large set of boundary singularities
Authors: Ghoussoub Nassif , Robert Frédéric
Published: May 2009

We solve variationally certain equations of stellar dynamics of the form
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="minus sigma-summation Underscript i Endscripts partial-differential Subscript i i Baseline u left-parenthesis x right-parenthesis equals StartFraction StartAbsoluteValue u EndAbsoluteValue Superscript p minus 2 Baseline u left-parenthesis x right-parenthesis Over dist left-parenthesis x comma script upper A right-parenthesis Superscript s Baseline EndFraction">

−

∑
i

∂

i
i

u
(
x
)
=

|

u

|

p
−
2

u
(
x
)

dist

(
x
,

A

)
s

-\sum _i\partial _{ii} u(x) =\frac {|u|^{p-2}u(x)}{\textrm {dist} (x,{\mathcal A} )^s}

in a domain

Ω
\Omega

of

R

n

\mathbb {R}^n

, where

A

{\mathcal A}

is a proper linear subspace of

R

n

\mathbb {R}^n

. Existence problems are related to the question of attainability of the best constant in the following inequality due to Maz’ya (1985):
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="0 greater-than mu Subscript s comma script upper P Baseline left-parenthesis normal upper Omega right-parenthesis equals inf left-brace integral Underscript normal upper Omega Endscripts StartAbsoluteValue nabla u EndAbsoluteValue squared d x vertical-bar u element-of upper H Subscript 1 comma 0 Superscript 2 Baseline left-parenthesis normal upper Omega right-parenthesis normal a normal n normal d integral Underscript normal upper Omega Endscripts StartFraction StartAbsoluteValue u left-parenthesis x right-parenthesis EndAbsoluteValue Superscript 2 Super Superscript star Superscript left-parenthesis s right-parenthesis Baseline Over StartAbsoluteValue pi left-parenthesis x right-parenthesis EndAbsoluteValue Superscript s Baseline EndFraction d x equals 1 right-brace comma">

0
>

μ

s
,

P

(
Ω
)
=
inf

{

∫

Ω

|

∇
u

|

2

d
x

|

u
∈

H

1
,
0

2

(
Ω
)

a
n
d

∫

Ω

|

u
(
x
)

|

2

⋆

(
s
)

|

π
(
x
)

|

s

d
x
=
1

}

,

0>\mu _{s,\mathcal {P}}(\Omega ) =\inf \left \{\int _{\Omega }|\nabla u|^2 dx\; \left |\; u\in H_{1,0}^2(\Omega ) \;\mathrm { and }\; \int _{\Omega }\frac {|u(x)|^{2^{\star }(s)}}{|\pi (x)|^s} dx=1\right .\right \},

\]
where

0
>
s
>
2

0>s>2

,

2

⋆

(
s
)
=

2
(
n
−
s
)

n
−
2

2^{\star }(s) =\frac {2(n-s)}{n-2}

and where

π
\pi

is the orthogonal projection on a linear space

P

\mathcal {P}

, where

dim

R

⁡

P

≥
2

\operatorname {dim}_{\mathbb {R}}\mathcal {P}\geq 2

(see also Badiale-Tarantello (2002)). We investigate this question and how it depends on the relative position of the subspace

P

⊥

{\mathcal P}^{\bot }

, the orthogonal of

P

\mathcal P

, with respect to the domain

Ω
\Omega

, as well as on the curvature of the boundary

∂
Ω

\partial \Omega

at its points of intersection with

P

⊥

{\mathcal P}^{\bot }

.
Bessel potentials, hitting distributions and Green functions
Authors: Byczkowski T. , Małecki J. , Ryznar M.
Published: May 2009

The purpose of the paper is to find explicit formulas for basic objects pertaining to the potential theory of the operator

(
I
−
Δ

)

α

/

2

(I-\Delta )^{\alpha /2}

, which is based on Bessel potentials

J

α

=
(
I
−
Δ

)

−
α

/

2

J_{\alpha }=(I-\Delta )^{-\alpha /2}

,

0
>
α
>
2

0>\alpha >2

. We compute the harmonic measure of the half-space and obtain a concise form for the corresponding Green function of the operator

(
I
−
Δ

)

α

/

2

(I-\Delta )^{\alpha /2}

. As an application we provide sharp estimates for the Green function of the half-space for the relativistic process.
Predictor correlation impacts machine learning algorithms: implications for genomic studies
Authors: Nicodemus Kristin K. , Malley James D.
Published: May 2009

Motivation: The advent of high-throughput genomics has produced studies with large numbers of predictors (e.g. genome-wide association, microarray studies). Machine learning algorithms (MLAs) are a computationally efficient way to identify phenotype-associated variables in high-dimensional data. There are important results from mathematical theory and numerous practical results documenting their value. One attractive feature of MLAs is that many operate in a fully multivariate environment, allowing for small-importance variables to be included when they act cooperatively. However, certain properties of MLAs under conditions common in genomic-related data have not been well-studied—in particular, correlations among predictors pose a problem.

Results: Using extensive simulation, we showed considering correlation within predictors is crucial in making valid inferences using variable importance measures (VIMs) from three MLAs: random forest (RF), conditional inference forest (CIF) and Monte Carlo logic regression (MCLR). Using a case–control illustration, we showed that the RF VIMs—even permutation-based—were less able to detect association than other algorithms at effect sizes encountered in complex disease studies. This reduction occurred when ‘causal’ predictors were correlated with other predictors, and was sharpest when RF tree building used the Gini index. Indeed, RF Gini VIMs are biased under correlation, dependent on predictor correlation strength/number and over-trained to random fluctuations in data when tree terminal node size was small. Permutation-based VIM distributions were less variable for correlated predictors and are unbiased, thus may be preferred when predictors are correlated. MLAs are a powerful tool for high-dimensional data analysis, but well-considered use of algorithms is necessary to draw valid conclusions.

Contact:  kristin.nicodemus@well.ox.ac.uk

Supplementary information:  Supplementary data are available at Bioinformatics online.
Bisoprolol in patients with heart failure and moderate to severe chronic obstructive pulmonary disease: a randomized controlled trial
Authors: Hawkins Nathaniel M. , MacDonald Michael R. , Petrie Mark C. , Chalmers George W. , Carter Roger , Dunn Francis G. , McMurray John J.V.
Published: May 2009

Aims

Heart failure (HF) and chronic obstructive pulmonary disease (COPD) frequently coexist. No study has prospectively examined the effects of beta‐blockade in those with both conditions.

Methods and results

We randomized 27 patients with HF and coexistent moderate or severe COPD to receive bisoprolol or placebo, titrated to maximum tolerated dose over 4 months. The primary outcome was forced expiratory volume in 1 s (FEV1). The study is registered with ClinicalTrials.gov, number: NCT00702156. Patients were elderly and predominantly male. Cardiovascular comorbidity, smoking history, and pulmonary function were similar in each group (mean FEV1 1.37 vs. 1.26 L, P = 0.52). A reduction in FEV1 occurred after 4 months following treatment with bisoprolol compared with placebo (−70 vs. +120 mL, P = 0.01). Reversibility following inhaled β2‐agonist and static lung volumes were not impaired by bisoprolol. All measures of health status exhibited a consistent non‐significant improvement, including the Short Form 36 physical and mental component scores (2.6 vs. 0.5 and 0.8 vs. −0.3, respectively), Minnesota Living with Heart Failure Questionnaire (−2.5 vs. 3.5) and Chronic Respiratory Questionnaire (0.07 vs. −0.24). The mean number of COPD exacerbations was similar in the bisoprolol and placebo groups (0.50 and 0.31, respectively, P = 0.44).

Conclusion

Initiation of bisoprolol in patients with HF and concomitant moderate or severe COPD resulted in a reduction in FEV1. However, symptoms and quality of life were not impaired.