bluuebunny/crossref_metadata_2025 huggingface dataset:
Some theoretical questions about the G‐particle‐hole hypervirial equation
Authors: Valdemoro C. , Alcoba D. R. , Tel L. M. , Pérez‐Romero E.
Published: August 2010

By applying a matrix contracting mapping, involving the G‐particle‐hole operator, to the matrix representation of the N‐electron density hypervirial equation, one obtains the G‐particle‐hole hypervirial (GHV) equation (Alcoba, et al., Int J Quant Chem 2009, 109, 3178). This equation may be solved by exploiting the stationary property of the hypervirials (Hirschfelder, J Chem Phys 1960, 33, 1462; Fernández and Castro, Hypervirial Theorems., Lecture Notes in Chemistry Series 43, 1987) and by following the general lines of Mazziotti's approach for solving the anti‐Hermitian contracted Schrödinger equation (Mazziotti, Phys Rev Lett 2006, 97, 143002), which can be identified with the second‐order density hypervirial equation. The accuracy of the results obtained with this method when studying the ground‐state of a set of atoms and molecules was excellent when compared with the equivalent full configuration interaction (FCI) quantities. Here, we analyze two open questions: under what conditions the solution of the GHV equation corresponds to a Hamiltonian eigenstate, and the possibility of extending the field of application of this methodology to the study of excited and multiconfigurational states. A brief account of the main difficulties that arise when studying this type of states is described. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Ab initio treatment of charge exchange in H+ + CH collisions
Authors: Bene E. , Halász G. J. , Vibók Á. , Errea L. F. , Méndez L. , Rabadán I. , Bacchus‐Montabonel M. C.
Published: August 2010

Calculations of charge transfer total cross section in proton collisions with CH are presented at collision energies 10 eV < E < 6.25 keV. Two‐state calculations using the sudden approximation for rotation and vibration do not show significant differences with respect to the simple Franck‐Condon approximation, which is appropriate for energies above 200 eV. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Analysis of vibrational modes of the P4 molecule through hyperspherical variants of the local orthogonal coordinates: The limit of dissociation in dimers
Authors: Ragni Mirco , Prudente Frederico V. , Bitencourt Ana C. P. , Barreto Patricia R. P.
Published: August 2010

In this work, we discuss the representation in different orthogonal coordinates sets of highly symmetric P4 molecule whose equilibrium configuration is tetrahedral. For this purpose, the H (or diatom–diatom) and Wigner orthogonal representations are used to study the singlet (ground) electronic state of the title molecule, whereas the V (or diatom–satellites) scheme is used in the triplet electronic state analysis. The equilibrium geometries and the respective electronic energies of Pn, n = 1,…,4, are determined using the coupled cluster and DFT methodologies. Moreover, the vibrational harmonic modes and the minimum energy path of the P4 dissociation in P2 dimers are calculated within DFT procedure. From these calculations, the diatom–diatom and Wigner vectors are used to analyze the behavior of vibrational modes, and the possible fragmentation channels (P4 → 2P2, P3 + P, P2 + 2P, 4P) are discussed. The presented results are compared, when available, with previous theoretical and experimental ones. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Relationships between complex core level spectra and materials properties
Authors: Nelin C. J. , Bagus P. S. , Ilton E. S. , Chambers S. A. , Kuhlenbeck H. , Freund H.‐J.
Published: August 2010

The XPS of many oxides are quite complex and there may be several peaks of significant intensity for each subshell. These peaks arise from many‐electron effects, which normally are treated with configuration interaction (CI) wavefunctions where static correlation effects are taken into account. It is common to use semiempirical methods to determine the matrix elements of the CI Hamiltonian and there are few rigorous CI calculations where parameters are not adjusted to fit experiment. In contrast, we present, in the present work, theoretical XPS spectra obtained with rigorous CI wavefunctions for CeO2 where the XPS are especially complex; several different core levels are studied. This study uses an embedded CeO8 cluster model to represent bulk CeO2 and the relativistic CI wavefunctions are determined using four‐component spinors from Dirac‐Fock calculations. In particular, we examine the importance of interatomic many‐body effects where there is a transfer of electrons from occupied oxygen 2p orbitals into empty cation orbitals as it is common to ascribe the complex XPS to this effect. We also contrast the importance of many‐body charge‐transfer effects for the isoelectronic cations of Ce4+ and La3+. The long‐range goal of this work is to relate the XPS features to the nature of the chemical bonding in CeO2 and we describe our progress toward this goal. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
1Se resonance States of two electron atoms by stabilization method
Authors: Saha Jayanta K. , Bhattacharyya S. , Mukherjee T. K. , Mukherjee P. K.
Published: August 2010

Stabilization method within variational framework has been applied to estimate the positions and widths of several doubly excited 1Se resonance states of two‐electron atoms [Z = 3–10] below N = 2 hydrogenic threshold. Multiexponent Hylleraas basis sets have been used to ensure the inclusion of electron correlation effects. Resonance parameters, namely the positions and widths of a number of such states, have been found for the first time and excellent agreement is observed for the resonance parameters of the states for which theoretical data already exist. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Determining molecule–particle reaction parameters
Authors: Madsen Marianne Sloth , Gross Allan , Mikkelsen Kurt V.
Published: August 2010

We present an approach for determining the detailed evolution of molecule–particle systems. Classical trajectory calculations have been performed for a molecule–particle system, where the molecule is SO2 and the particle is given by a water cluster. We present the detailed mechanisms of the energy transfer processes as the molecule approaches the particle and the reaction rates such as sticking coefficients. This study shows that the sticking coefficient for SO2 on water is close to one at stratospheric temperatures. These results are compared with those obtained using quantum mechanics/molecular mechanics in combination with statistical mechanics. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Free energy and structure of polyproline peptides: An ab initio and classical molecular dynamics investigation
Authors: Moradi Mahmoud , Lee Jung‐Goo , Babin Volodymyr , Roland Christopher , Sagui Celeste
Published: August 2010

Depending on their environment, polyproline peptides form chiral helices that may be either left‐ (PPII) or right‐handed (PPI). Here, we have characterized both the structure and free energy landscapes of Ace‐(Pro)n‐Nme (n an integer less than 13) peptides, in vacuo and in implicit water environments. Both ab initio and classical molecular dynamics methods were used. In terms of the latter, we used a recently developed Adaptively Biased Molecular Dynamics (ABMD) method in conjunction with three different force fields (ff99, ff99SB, ff03) and two different Generalized Born models for the implicit solvent environment. Specifically, the ABMD method provides for an accurate description of the free energy landscapes in terms of a set of collective variables, which were carefully chosen as to reflect the “slow modes” of the polyproline peptides. These are primarily based on the cis‐trans isomerization associated with the prolyl bonds. In agreement with recent experimental results, the peptides form not only the pure PPII or PPI structures but also a large number of stable conformers having more or less similar free energies, whose distributions we have characterized. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Development of approximately spin projected energy derivatives for biradical systems
Authors: Kitagawa Y. , Saito T. , Nakanishi Y. , Kataoka Y. , Matsui T. , Kawakami T. , Okumura M. , Yamaguchis K.
Published: August 2010

In this article, we summarize a recent progress in our spin‐projected energy derivative method for broken‐symmetry (BS) solutions of singlet biradical systems. Because, the spin projection procedure that is based on the approximate spin projection (AP) method does not involve a spin contamination error, it improves the accuracy of an optimized geometry and a calculated vibrational frequency for the singlet biradical molecule with the low cost of computation. To examine the spin contamination error in the BS energy derivatives and to demonstrate the efficiency of the AP method, we carry out the geometry optimization and the vibrational calculation of singlet CR2 (R = H, F, and CH3) molecules that are the typical singlet biradical systems. The results indicate that the error in the singlet CH2 and C(CH3)2 molecules are serious, however, the error in the singlet CF2 molecule, which has electron withdrawing fluorine atoms is negligible. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Coupled‐cluster theories for the polarizable continuum model. II. Analytical gradients for excited states of molecular solutes by the equation of motion coupled‐cluster method
Authors: Cammi R.
Published: August 2010

The theory for the analytical energy gradients of excited electronic state described by equation of motion couped‐cluster method (EOM‐CC) (Stanton, J Chem Phys, 1993, 99, 8840) has been generalized to molecules in solution within the polarizable continuum model (PCM) framework (Miertuš et al. Chem Phys 1981, 55, 117). The final equations of the PCM‐EOM gradients are developed at the single and double excitation level (CCSD) and are cast in a form similar to that developed for the ground state CC energy derivatives of solvated molecules (Cammi, J Chem Phys 2009, 131, 164104), involving contraction of effective one‐ and two‐particle density matrices with differentiated one‐ and two‐electron integrals over atomic orbitals. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
UNO‐ and ULO‐MRCC(Mk), AP‐UCC and AP‐UBD approaches to diradical systems
Authors: Nishihara Satomich , Yamanaka Shusuke , Saito Tohru , Kitagawa Yasutaka , Kawakami Takashi , Okumura Mitsutaka , Yamaguchi Kizashi
Published: August 2010

In this article, we performed spin‐unrestricted Hartree Fock (UHF) based coupled‐cluster (CC) and Bruckner CC double calculations of methylene, fluorine, HHeH diradical, and ozone. Mukherjee‐type (Mk) Multireference coupled‐cluster (MRCC) calculations of these species were also conducted by the use of UHF natural orbital (UNO) and UHF localized natural orbitals (ULO) as reference orbitals to elucidate size‐consistent error. Comparing calculated results of spin‐unrestricted Hartree‐Fock based coupled‐cluster (UCC) and spin‐unrestricted Bruckner‐Double (UBD) with those of MkMRCC, it was found that spin‐contamination errors of UCC and UBD solutions still remained, though this type of errors for these solutions was considered to be negligible in general. The comparison also revealed scope and applicability of approximate spin‐projection (AP) scheme for UCC and UBD, indicating that the AP procedure corrected spin‐contamination errors to yield good agreement with MRCC in energy. We also performed pure‐ and hybrid‐ density functional theory (DFT) calculations of the same systems, and those calculations provided reasonable singlet‐triplet energy gaps, which were qualitatively good agreement with those of MRCC, AP‐UCC, and AP‐UBD calculations. Implications of the computational results are discussed in relation to applicability of hybrid DFT to large superexchange coupled systems. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
On the simple constrained‐search reformulation of the Hohenberg–Kohn theorem to include degeneracies and more (1964–1979)
Authors: Levy Mel
Published: August 2010

The constrained‐search reformulation provides a transparent proof of the Hohenberg–Kohn theorem, while extending it to include degeneracies, solving the w‐representability problem, and more. This proof, as first presented at the 1979 Sanibel meeting, is reviewed within the context of a brief historical perspective and my interactions at that meeting. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Generalized Bode envelopes and generalized Nyquist theorem for analysis of uncertain systems
Authors: Nakhmani A. , Lichtsinder M. , Zeheb E.
Published: August 2010

This work is concerned with analysis of uncertain control systems, with regard to clustering of poles inside a simple symmetric bounded contour. We present and use the generalized Bode envelopes, generalized Mikhailov theorem, and the generalized Nyquist theorem for the simultaneous analysis of stability and quality of transient response of uncertain systems. Our results allow one to determine the number of open‐ and closed‐loop poles inside the given symmetric simply connected contour, for the entire uncertain family. The proposed method is computationally efficient and appropriate for solving complex control analysis problems, as evidenced in the examples. Copyright © 2010 John Wiley & Sons, Ltd.
Minimum‐variance control of astronomical adaptive optic systems with actuator dynamics under synchronous and asynchronous sampling
Authors: Raynaud H.‐F. , Correia C. , Kulcsár C. , Conan J.‐M.
Published: August 2010

Adaptive optic (AO) systems are now routinely used in ground‐based telescopes to counter the effects of atmospheric turbulence. A deformable mirror (DM) generates a correction wavefront, which is subtracted from the turbulent wavefront using measurements of the residual phase provided by a wavefront sensor (WFS). Minimizing the variance of the residual phase defines a sampled data control problem combining a continuous time minimum‐variance (MV) performance criterion with a discrete‐time controller. For a fairly general class of linear time‐invariant DM and turbulence WFS models, this control problem can be transformed into an equivalent discrete‐time LQ optimization problem involving a set of (discrete‐time) control‐sufficient statistics of the incoming continuous‐time turbulence. This paper shows how to constructively solve this MV problem in the presence of DM's dynamics, starting from continuous‐time models of DM and turbulence. This result is extended to the case of asynchronous DM/WFS sampling. An illustrative application to optimal control of tip‐tilt turbulent modes for the European extremely large telescope in the presence of first‐order DM's dynamics is presented. Copyright © 2010 John Wiley & Sons, Ltd.
Consensus of second‐order multi‐agent systems with exogenous disturbances
Authors: Yang Hongyong , Zhang Zhenxing , Zhang Siying
Published: August 2010

In this paper, the consensus of second‐order multi‐agent dynamical systems with exogenous disturbances is studied. A pinning control strategy is designed for a part of agents of the multi‐agent systems without disturbances, and this pinning control can bring multiple agents' states to reaching an expected consensus track. Under the influence of the disturbances, disturbance observers‐based control (DOBC) is developed for disturbances generated by an exogenous system to estimate the disturbances. Asymptotical consensus of the multi‐agent systems with disturbances under the composite controller can be achieved for fixed and switching topologies. Finally, by applying an example of multi‐agent systems with switching topologies and exogenous disturbances, the consensus of multi‐agent systems is reached under the DOBC with the designed parameters. Copyright © 2010 John Wiley & Sons, Ltd.
Guaranteed cost control of uncertain discrete‐time singular Markov jump systems with indefinite quadratic cost
Authors: Ma Shuping , Boukas El‐Kébir
Published: August 2010

The guaranteed cost control problem for discrete‐time singular Markov jump systems with parameter uncertainties is discussed. The weighting matrix in quadratic cost function is indefinite. For full and partial knowledge of transition probabilities cases, state feedback controllers are designed based on linear matrix inequalities method which guarantee that the closed‐loop discrete‐time singular Markov jump systems are regular, causal and robust stochastically stable, and the cost value has a zero lower bound and a finite upper bound. A numerical example to illustrate the effectiveness of the method is given in the paper. Copyright © 2010 John Wiley & Sons, Ltd.
Antisubmarine warfare applications for autonomous underwater vehicles: The GLINT09 sea trial results
Authors: Hamilton Michael J. , Kemna Stephanie , Hughes David
Published: August 2010

Surveillance in antisubmarine warfare (ASW) has traditionally been carried out by means of submarines or frigates with towed arrays. These techniques are manpower intensive. Alternative approaches have recently been suggested concerning distributed mobile and stationary sensors, such as sonobuoys and autonomous underwater vehicles (AUVs). To field a fully operational system, many technological hurdles need to be overcome. These include battery life, limited acoustic communications ranges, incorporating sonar signal processing on the AUV's embedded hardware, and increasing autonomy to ensure that the system as a whole acts in a sensible and appropriate fashion. The main thrust of this paper is how the latter two issues have been addressed for a real experimental system and how the proposed solutions have been demonstrated at sea. This paper describes ongoing development at the NATO Undersea Research Centre (NURC) to construct an autonomous distributed sensor system that uses AUVs for ASW applications. In a series of at‐sea experiments, we have demonstrated real‐time processing—incorporating traditional ASW processing as far as tracking—and adaptive autonomous behaviors, which concern AUV navigation to optimize target localization. This paper describes the hardware and software configurations that facilitated the rapid development of this system and details the recent at‐sea successes that have been demonstrated with our AUV, towed arrays, and active acoustic sources. Results are given of our most recent at‐sea trial, GLINT09, held in the summer of 2009, when an AUV with a towed array detected and maneuvered in response to an active source. © 2010 Wiley Periodicals, Inc.
Comparison of empirical and theoretical remote sensing based bathymetry models in river environments
Authors: Flener C. , Lotsari E. , Alho P. , Käyhkö J.
Published: August 2010

Knowledge of underwater morphology is an essential component of many hydrological and environmental applications such as flood modelling and lotic habitat mapping. Remote sensing allows modelling of bathymetry at spatial scales that are impossible to achieve with traditional methods. However, the use of passive remote sensing for modelling water depth in fluvial environments remains a challenge.

Different methods of computing bathymetry models based on remotely sensed imagery combined with ground measurements for calibration were investigated in order to produce a digital bathymetry model of a reach of the river Tana in Lapland. An empirical deep water correction model was evaluated together with theoretical hydraulically assisted bathymetry (HAB) models.

The empirical model produced good results, correlating to known depths at 0.98 (R
2 = 0.96) with a mean error of ±12.0 cm. It was demonstrated that usable levels of accuracy can be achieved with data that had previously been considered unsuitable for bathymetry modelling. Some issues related to channel substrate were addressed. The models based on hydraulic theory were tested for the first time outside the area they were developed in. Both models were found to be rather sensitive to certain assumptions, such as the channel friction parameter. The HAB models are able to produce relative depth estimates that can under certain conditions approach actual depths at accuracies similar to the empirical model.

Extensive accuracy assessment was performed in order to evaluate the vertical as well as the spatial accuracy of the three models. Copyright © 2010 John Wiley & Sons, Ltd.
Using airborne scanning laser altimetry (LiDAR) to estimate surface connectivity of floodplain water bodies
Authors: Negishi J. N. , Sagawa S. , Sanada S. , Kume M. , Ohmori T. , Miyashita T. , Kayaba Y.
Published: August 2010

This study tested the applicability of airborne scanning laser altimetry (LiDAR) for characterizing surface connectivity of floodplain water bodies by comparing it with in situ measurements of water levels, and examined whether LiDAR derived data accurately predicted the occurrence of globally imperilled unionid mussels. We intensively examined 10 isolated and 3 connected floodplain water bodies (IWBs and CWBs, respectively) located within a 15‐km lowland segment of the Kiso River in Japan. Using a digital elevation model (DEM) of floodplain ground surface, which is derived from LiDAR, and water surface DEM, which is obtained from records of water level fluctuations, the frequency of surface connectivity between IWBs and the main channel (inundation frequency) was calculated. Inundation frequency of IWBs was also measured in situ using water level and temperature probes. Also, the occurrence of mussels in CWBs and IWBs were examined. LiDAR derived data well predicted in situ derived one with a high level of accuracy (r2 > 0.77), validating the LiDAR‐based approach. Some errors existed in the predictive model, indicating that the applicability of LiDAR data is limited by its spatial resolution and snapshot nature. The occurrence of mussels was positively explained by an increasing level of inundation frequency, and the high accuracies of empirical models were validated using data for other 67 water bodies within the study segment. This study overall demonstrated a high potential of LiDAR data for efficiently monitoring hydrological and biological conditions of floodplain water bodies in the Kiso River and beyond. Copyright © 2010 John Wiley & Sons, Ltd.
Evaluation of δD and δ18O as natural markers of invertebrate source environment and dispersal in the middle Mississippi River‐floodplain ecosystem
Authors: Myers D. J. , Whitledge G. W. , Whiles M. R.
Published: August 2010

Movement of invertebrates among large rivers, tributaries, and floodplain lakes or dispersal of adult aquatic insects from riverine or floodplain habitats may provide important subsidies to food webs in receiving habitats. Intensive sampling at habitat interfaces and artificial labelling are two approaches to assess freshwater invertebrate dispersal, but these are difficult to implement at a landscape scale. Natural chemical tracers have been used to track dispersal of fishes and marine invertebrates, but the potential applicability of stable isotope ratios as natural tracers of invertebrate dispersal in freshwater environments has not been assessed. We evaluated stable hydrogen and oxygen isotopes (δD and δ18O) as natural markers of source environment and dispersal of macroinvertebrates in the middle Mississippi River, tributaries and floodplain wetlands. Water and invertebrates were collected from 12 sites during 2007–2008. Water δD and δ18O differed among the river, its tributaries, and floodplain wetlands and were strongly correlated with invertebrate δD and δ18O. Variability in invertebrate δ18O rendered it ineffective as an indicator of invertebrate source environment. Mean δD of Mississippi River invertebrates differed from δD of invertebrates from floodplain wetlands; δD distinguished invertebrates from these two environments with >80% accuracy. Neither δD nor δ18O of aquatic insects changed following emergence from their natal site. Preservation method (ethanol or freezing) did not affect invertebrate δD or δ18O. Invertebrate δD may be a useful natural tracer of natal environment and dispersal in the Mississippi River‐floodplain ecosystem and other freshwater systems where spatial variation in water δD is present. Copyright © 2010 John Wiley & Sons, Ltd.
Novel plant communities limit the effects of a managed flood to restore riparian forests along a large regulated river
Authors: Cooper D. J. , Andersen D. C.
Published: August 2010

Dam releases used to create downstream flows that mimic historic floods in timing, peak magnitude and recession rate are touted as key tools for restoring riparian vegetation on large regulated rivers. We analysed a flood on the 5th‐order Green River below Flaming Gorge Dam, Colorado, in a broad alluvial valley where Fremont cottonwood riparian forests have senesced and little recruitment has occurred since dam completion in 1962. The stable post dam flow regime triggered the development of novel riparian communities with dense herbaceous plant cover. We monitored cottonwood recruitment on landforms inundated by a managed flood equal in magnitude and timing to the average pre‐dam flood. To understand the potential for using managed floods as a riparian restoration tool, we implemented a controlled and replicated experiment to test the effects of artificially modified ground layer vegetation on cottonwood seedling establishment. Treatments to remove herbaceous vegetation and create bare ground included herbicide application (H), ploughing (P), and herbicide plus ploughing (H + P). Treatment improved seedling establishment. Initial seedling densities on treated areas were as much as 1200% higher than on neighbouring control (C) areas, but varied over three orders of magnitude among the five locations where manipulations were replicated. Only two replicates showed the expected seedling density rank of (H + P) > P > H> C. Few seedlings established in control plots and none survived 1 year. Seedling density was strongly affected by seed rain density. Herbivory affected growth and survivorship of recruits, and few survived nine growing seasons. Our results suggest that the novel plant communities are ecologically and geomorphically resistant to change. Managed flooding alone, using flows equal to the pre‐dam mean annual peak flood, is an ineffective riparian restoration tool where such ecosystem states are present and floods cannot create new habitat for seedling establishment. This problem significantly limits long‐term river and riparian management options. Copyright © 2010 John Wiley & Sons, Ltd.
Discriminative frequent subgraph mining with optimality guarantees
Authors: Thoma Marisa , Cheng Hong , Gretton Arthur , Han Jiawei , Kriegel Hans‐Peter , Smola Alex , Song Le , Yu Philip S. , Yan Xifeng , Borgwardt Karsten M.
Published: August 2010

The goal of frequent subgraph mining is to detect subgraphs that frequently occur in a dataset of graphs. In classification settings, one is often interested in discovering discriminative frequent subgraphs, whose presence or absence is indicative of the class membership of a graph. In this article, we propose an approach to feature selection on frequent subgraphs, called CORK, that combines two central advantages. First, it optimizes a submodular quality criterion, which means that we can yield a near‐optimal solution using greedy feature selection. Second, our submodular quality function criterion can be integrated into gSpan, the state‐of‐the‐art tool for frequent subgraph mining, and help to prune the search space for discriminative frequent subgraphs even during frequent subgraph mining. Copyright © 2010 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 3: 302‐318, 2010
Dimensions of communication in urban science education: Interactions and transactions
Authors: Emdin Christopher
Published: August 2010

This paper is birthed from my lifelong experiences as student, teacher, administrator, and researcher in urban science classrooms. This includes my years as a minority student in biology, chemistry, and physics classrooms, 10 tears as science teacher and high school science department chair, 5‐years conducting research on youth experiences in urban science classrooms, and current work in preparing science teachers for teaching in urban schools. These experiences afford me both emic and etic lenses through which to view urban science classrooms and urban youth communities. This paper, both experiential and research based, forms an ethnography of urban youth communication and introduces the science education community to an aspect of science teaching that has been overlooked in traditional science education research. In documenting urban youth communication across social fields, this paper contributes to the research in science education that addresses science talk with urban youth in science classrooms (C. Ballenger, 1997; P. Gee, 1997). More specifically, I utilize the lenses I bring to urban science education research to interrogate the larger research questions of whether urban students' modes of communication are supported in the urban science classroom and the effects of this support or lack thereof on true participation/engagement of urban youth in science. © 2010 Wiley Periodicals, Inc. Sci Ed 95: 1–20, 2011
The interaction of H2O with Fe‐doped SrTiO3(100) surfaces
Authors: Voigts F. , Argirusis C. , Maus‐Friedrichs W.
Published: August 2010

The interaction of H2O with 0.013 at.% Fe‐doped SrTiO3(100) was investigated in situ with Metastable Induced Electron Spectroscopy (MIES), Ultraviolet Photoelectron Spectroscopy (UPS) and XPS at room temperature. Low Energy Electron Diffraction (LEED) was applied to gather information about the surface termination. To clear up the influence of surface defects, untreated and weakly sputtered SrTiO3 surfaces were investigated. The sputtering results in the formation of oxygen‐related defects in the top surface layer.

The interaction of untreated SrTiO3 surfaces with H2O is only weak. Small amounts of OH groups can be identified only with MIES due to its extreme surface sensitivity. Sputtered surfaces show a larger OH formation. Nondissociative H2O adsorption is not observed. We therefore conclude that the exposure of H2O to SrTiO3(100) results in the dissociation near surface defects only, resulting in the formation of surface hydroxyl groups. Copyright © 2010 John Wiley & Sons, Ltd.
Functionalized imidazolium wear‐resistant ionic liquid ultrathin films for MEMS/NEMS applications
Authors: Mo Yufei , Huang Fuchuan , Zhao Fei
Published: August 2010

As a kind of new material, ionic liquids (ILs) are considered a new type of lubricant for micro/nanoelectromechanical system (M/NEMS) due to their excellent thermal and electrical conductivity. However, so far, only a few reports have investigated the friction and wear of thin films of these materials at the micro scale. Evaluating the nanoscale tribological performance of ILs when applied as films of a few nanometers thickness on a substrate is a critical step for their application in M/NEMS devices. To achieve this purpose, IL thin films with four kinds of anions were synthesized and prepared on single‐crystal silicon wafers by the dip‐coating method. Film thickness was determined by the ellipsometric method. Their surface morphologies were observed by means of atomic force microscopy (AFM). The nano and micro tribological properties of the IL films were investigated by a friction force microscope (FFM)with a spherical probe and a UMT‐2MT tribotester, respectively. The corresponding morphologies of the wear tracks of the IL films were examined using a three‐dimensional non‐contact interferometric microscope. The impact of temperature on the adhesion behavior was studied, as well as the effect of sliding frequency and load on the friction coefficient, load bearing capacity and anti‐wear durability. It was found that friction, adhesion and durability of IL films were strongly dependent on their anionic molecular structures, wettability and ambient environment. Copyright © 2010 John Wiley & Sons, Ltd.
Adsorption of carbon monoxide on Pd low‐index surfaces and (110) reconstructed surface
Authors: Zhang Jing , Wang Zhen , Wang Ze Xin
Published: August 2010

Adsorption and diffusion of carbon monoxide on Pd low‐index surfaces and missing‐row Pd (110) reconstructed surface have been investigated by the extended London–Eyring–Polyani–Sato (LEPS) method constructed by means of a five‐parameter Morse potential. All critical characteristics, such as adsorption site, adsorption geometry, binding energy, CO vibrational frequency have been obtained and compared with the experimental and theoretical data. On these surfaces, the stable adsorption sites of CO are changed with increasing CO coverage. On the missing‐row Pd (110) reconstructed surface, there are five stable adsorption sites: H1, H2 (H1 and H2 are threefold hollow sites on (111) subsurface), B (bridge site on the second layer), SB (short‐bridge site), and T (top site). Copyright © 2010 John Wiley & Sons, Ltd.
Slope estimation in structural line‐segment heteroscedastic measurement error models
Authors: McAssey Michael P. , Hsieh Fushing
Published: August 2010

This paper extends the line‐segment parametrization of the structural measurement error (ME) model to situations in which the error variance on both variables is not constant over all observations. Under these conditions, we develop a method‐of‐moments estimate of the slope, and derive its asymptotic variance. We further derive an accurate estimator of the variability of the slope estimate based on sample data in a rather general setting. We perform simulations that validate our results and demonstrate that our estimates are more precise than estimates under a different model when the ME variance is not small. Finally, we illustrate our estimation approach using real data involving heteroscedastic ME, and compare its performance with that of earlier models. Copyright © 2010 John Wiley & Sons, Ltd.
Linear mixed models for skew‐normal/independent bivariate responses with an application to periodontal disease
Authors: Bandyopadhyay Dipankar , Lachos Victor H. , Abanto‐Valle Carlos A. , Ghosh Pulak
Published: August 2010

Bivariate clustered (correlated) data often encountered in epidemiological and clinical research are routinely analyzed under a linear mixed model (LMM) framework with underlying normality assumptions of the random effects and within‐subject errors. However, such normality assumptions might be questionable if the data set particularly exhibits skewness and heavy tails. Using a Bayesian paradigm, we use the skew‐normal/independent (SNI) distribution as a tool for modeling clustered data with bivariate non‐normal responses in an LMM framework. The SNI distribution is an attractive class of asymmetric thick‐tailed parametric structure which includes the skew‐normal distribution as a special case. We assume that the random effects follow multivariate SNI distributions and the random errors follow SNI distributions which provides substantial robustness over the symmetric normal process in an LMM framework. Specific distributions obtained as special cases, viz. the skew‐t, the skew‐slash and the skew‐contaminated normal distributions are compared, along with the default skew‐normal density. The methodology is illustrated through an application to a real data which records the periodontal health status of an interesting population using periodontal pocket depth (PPD) and clinical attachment level (CAL). Copyright © 2010 John Wiley & Sons, Ltd.
Effects of alliances, time, and network cohesion on the initiation of foreign sales by new ventures
Authors: Yu Jifeng , Gilbert Brett Anitra , Oviatt Benjamin M.
Published: August 2010

In this study, we seek to advance the network perspective on new venture internationalization by examining the role of networks in accelerating new venture sales into foreign markets. We propose that knowledge derived from ventures' technology and marketing alliances increases the likelihood that new ventures begin exploiting opportunities in international markets. We also argue that the extent to which the networks open the venture to new knowledge or constrain it to knowledge already shared among the partners will influence the initiation of foreign sales by a venture. Using a longitudinal dataset of 118 ventures in the U.S. biotechnology industry, we confirm that different types of alliances (and, therefore, different types of knowledge—technology and marketing knowledge) differentially impact the likelihood of new venture internationalization. Moreover, network cohesion among venture alliances increases the likelihood that marketing alliances will promote initial foreign market sales, but decreases the likelihood that technology alliances will do so. Our research is a timely response to a call for the study of interactive effects among network structure, complex tasks, and time, and it provides a possible explanation for certain unexpected findings in studies that did not consider the effects of time. Copyright © 2010 John Wiley & Sons, Ltd.
Corporate Governance and returns on information technology investment: evidence from an emerging market
Authors: Ho Joanna L. Y. , Wu Anne , Xu Sean Xin
Published: August 2010

Prior studies have reported mixed findings on the impact of corporate information technology (IT) investment on firm performance. This study investigates the effect of corporate governance, an important management control mechanism, on the relation between IT investment and firm performance in the Taiwanese electronics industry. Specifically, we explore board independence and foreign ownership, which have increasingly become salient factors concerning corporate governance in emerging markets. We address their roles across firms of different sizes and in industries where degrees of competitiveness run a wide gamut. Our results show a positive moderating effect of board independence on the IT investment‐firm performance relation, especially when competition intensifies. Furthermore, we find that the greater the foreign ownership in small firms, the more positive the IT investment‐firm performance relation, suggesting that foreign investors may bring IT expertise to help small firms reap the benefits of using IT. Copyright © 2010 John Wiley & Sons, Ltd.
Fear and distrust in global software engineering projects
Authors: Piri Arttu , Niinimäki Tuomas , Lassenius Casper
Published: August 2010

When global software engineering (GSE) is understood as knowledge intensive collaborative work, many of the reasons for the problems encountered in GSE projects can be traced back to the social conditions framing the collaboration between people at different physical sites. A total of 59 interviews were conducted in eight GSE projects of two large software companies with sites in Finland and other countries. As a result of categorization of problems related to group relations, the lack of trust between the main site and the other sites, and the fear of negative personal consequences among the project employees at the main site due to introduction of GSE were found to be the major problems in the projects. Our analysis suggests that poorly communicated reasoning for GSE can lay the ground for fear and for distrust between employees at remote sites. Unfulfilled cognitive expectations and fear related to one's professional future were found to be the sources of distrust toward employees at off‐site locations. The main contribution of this study is a novel empirical description of the linkages between fear and distrust in GSE. In addition, practical implications to effectively implement an organizational change from collocated development to distributed development are suggested. Copyright © 2010 John Wiley & Sons, Ltd.
Software disasters—understanding the past, to improve the future
Authors: McQuaid Patricia A.
Published: August 2010

Over the years, there have been several major software disasters, resulting from poor software project management, poor risk assessment, and poor development and testing practices. The results of the disasters range from project delays, project cancelations, loss of millions of dollars of equipment, to human fatalities. It is important to study software disasters, to alert developers and testers to be ever vigilant, and to understand that huge catastrophes can arise from what seem like small problems. This paper examines such failures as the Mars Polar Lander, the Patriot missile, and the Therac‐25 radiation deaths. The focus of the paper is on the factors that led to these problems, an analysis of the problems, and the lessons to be learned that relate to software engineering, safety engineering, government and corporate regulations, and oversight by users of the systems. A model named STAMP, Systems‐Theoretic Accident Modeling and Process, will be introduced, as a model to analyze these types of accidents. This model is based on systems theory, where the focus is on systems taken as a whole, as opposed to traditional failure‐event models where the parts are examined separately. It is by understanding the past, that we can improve the future. Copyright © 2010 John Wiley & Sons, Ltd.
The SPI manifesto and the ECQA SPI manager certification scheme
Authors: Korsaa Morten , Biro Miklos , Messnarz Richard , Johansen Jörn , Vohwinkel Detlef , Nevalainen Risto , Schweigert Tomas
Published: August 2010

Software process improvement (SPI) can be seen as a profession having its own competence needs and its own community of interest. European projects EQN and EU Cert have defined skill sets and a common certification scheme for about 20 professions, mainly in the IT domain. European Certification and Qualification Association ECQA is created to manage certification and provide the necessary infrastructure. A common way to approach the IT domain from a process perspective is the ‘3S’ concept (Software, Systems, Services). Software process can be seen as the first spearhead among these. The first software process models, such as CMM and SPICE, have already existed for about 20 years. With all the experience that the models bring, it is reasonable to start the PI profession from the software process. Software Process Improvement Manager (SPI Manager) is one of the new topics in ECQA. The development of the SPI Manager training and certification scheme has been done in many small steps so far. This paper explains the current structure and the main components of SPI Manager competences, training needs and the certification scheme. Several other schemes will be developed in the future for process improvement‐related competences. The current version of the SPI Manager skill set is mainly based on software, systems and service processes and their related reference models. It could also be used in the future in domains other than IT. Copyright © 2010 John Wiley & Sons, Ltd.
KASL‐II: a dynamic four‐loop model for knowledge sharing and learning
Authors: Georgiadou Elli , Siakas Kerstin V.
Published: August 2010

Knowledge sharing is by far the most important component of a knowledge management programme. Organizations strive to gain competitive advantage through efficiencies. When organizations realize that organizational knowledge is by far the most valuable resource, they need to find ways for efficient and effective knowledge sharing. We explore the barriers to knowledge sharing especially in virtual and multicultural teams. In particular, we unfold the human and cultural challenges that can create added competitive value for virtual and networked organizations. We conclude that the ideal environment and working practices will be to change the mindset and behaviour of team members so that instead of perceiving knowledge sharing as an extra task for the team members, isolated from the knowledge of other team members, it (knowledge sharing) becomes the natural way to work for everyone. Finally, we propose the dynamic knowledge acquisition and sharing lifecycle (KASL‐II) model for aiding the knowledge sharing process by showing the stages of translating an organization's mission and goals into objectives, and how decisions and actions operate for materialising these objectives. Copyright © 2010 John Wiley & Sons, Ltd.
Make test process assessment similar to software process assessment—the Test SPICE approach
Authors: Steiner Michael , Blaschke Monique , Philipp Michael , Schweigert Tomas
Published: August 2010

This article presents an ISO/IEC 15504 II conformant test assessment approach. It argues the need for such a method by reviewing the common approaches of ISTQB, TMM and TPI/TMAP and it outlines the first version of Test SPICE. The paper shows how ISO/IEC 15504 V was used as a starting point and it describes the actual model. Copyright © 2010 John Wiley & Sons, Ltd.
Evaluation of multi‐tasking software system performance with consideration of module dependency
Authors: Lee Chong Hyung , Kim Yong‐Ha , Park Dong Ho
Published: August 2010

This paper proposes new stochastic models that describe the task processing by the Markovian software availability model with perfect debugging and study the method to evaluate the system performance for the multi‐tasking software system having several modules. We assume that the software system, which is integrated by all modules, can process multiple tasks simultaneously. Each task, which is to be processed, is assumed to have multiple subtasks that are processed by the corresponding modules of the software system. Based on these models, we derive several performance measures, such as the expected numbers of subtasks and tasks whose processes can be completed within a certain time interval and the completion probability for each subtask and task. We also discuss the impacts that the number of modules constituting the system has on such performance measures. Furthermore, we consider the notion of module dependency for evaluation of certain probabilities of our interest and study its effects on such probabilities. Numerical examples are provided to illustrate our proposed models. Copyright © 2010 John Wiley & Sons, Ltd.
Toward trustworthy software process models: an exploratory study on transformable process modeling
Authors: Zhang He , Kitchenham Barbara , Jeffery Ross
Published: August 2010

Software process modeling and simulation have become effective tools for support of software process management and improvement over the past two decades. They have recently been integrated into the Trustworthy Process Management Framework (TPMF) as the infrastructural components to facilitate the delivery of trustworthy software products. This paper proposes the concept of Trustworthy Software Process Models as inputs to TPMF and introduces transformable process modeling for supporting effective and productive development of trustworthy process models. Furthermore, this paper undertakes an exploratory study on process model transformation by investigating and comparing process modeling semantics between quantitative (e.g., System Dynamics, SD) and qualitative forms of modeling and simulation. By following the model transformation scheme, a quantitative continuous (SD) software evolution process model is successfully transformed into its qualitative form for simulation. The results present the different capabilities and performance between these two modeling paradigms, as well as the possible benefits and interesting perspectives of transformable process modeling. Copyright © 2010 John Wiley & Sons, Ltd.