bluuebunny/crossref_metadata_2025 huggingface dataset:
Between Kant and Pufendorf: humanitarian intervention, statist anti-cosmopolitanism and critical international theory
Authors: DEVETAK RICHARD
Published: July 2007

Immanuel Kant and Samuel Pufendorf were both exercised by the relationship between politics, morality and lawful authority; a relationship that goes to the heart of the sovereign state’s existence and legitimacy. However, while Kant defended the authority of the moral law, believing morality provides higher authoritative norms than the sovereign state, Pufendorf defends the political morality of authority, believing the sovereign state should submit to no higher moral norms. The rivalry between these two positions is reprised in current debate between cosmopolitanism and statism over humanitarian intervention. Arguing against statism, this article defends a Habermasian-style critical international theory which affords a ‘cosmopolitanism without imperialism’.
Two-scale convergence for nonlinear Dirichlet problems in perforated domains
Authors: Casado-Díaz J.
Published: July 2007

The aim of the present paper is to adapt the method of two-scale convergence to the homogenization of a pseudomonotone Dirichlet problem in perforated domains with periodic structure. The limit problem and a corrector result are obtained.
Universal phantom maps out of loop spaces
Authors: Iriye K.
Published: July 2007

We consider the universal phantom map out of a non-finite loop space. First we obtain a necessary and sufficient condition for the universal phantom map out of ΩG for a simply connected compact Lie group G to be essential. Next we prove that the universal phantom map out of ΩkX is essential for all k ≥ 2 if X is a simply connected non-contractible finite CW-complex. Ingredients in the proof are the Browder's ∞-implication argument and the Eilenberg–Moore spectral sequence.
Phragmen–Lindelöf theorems and the asymptotic behaviour of solutions of quasilinear elliptic equations in slabs
Authors: Jin Z. , Lancaster K.
Published: July 2007

The asymptotic behaviour of solutions of second-order quasilinear elliptic partial differential equations defined on unbounded domains in Rn contained in strips (when n = 2) or slabs (when n > 2) is investigated when such solutions satisfy Dirichlet boundary conditions and the Dirichlet boundary data have appropriate asymptotic behaviour at infinity. We prove Phragmèn–Lindelöf theorems for large classes of elliptic operators, including uniformly elliptic operators and operators with well-defined genre, establish exponential decay estimates for uniformly elliptic operators when the Dirichlet boundary data vanish outside a compact set, establish the uniqueness of solutions, and give examples of solutions for non-uniformly elliptic operators which decay but do not decay exponentially. Our principal theorems are proven using special barrier functions; these barriers are constructed by considering an operator associated to our original operator.
Minimizing non-convex multiple integrals: a density result
Authors: Celada P. , Perrotta S.
Published: July 2007

We consider variational problems of the form

where Ω is a bounded open set in RN, f : RN → R is a possibly non-convex lower semicontinuous function with p-growth at infinity for some 1 < p < ∞, and the boundary datum u0 is any function in W1, p (Ω). Assuming that the convex envelope f** of f is affine on each connected component of the set {f** < f}, we prove the existence of solutions to ( P) for every continuous function g such that (i) g has no strict local minima and (ii) every convergent sequence of extremum points of g eventually belongs to an interval where g is constant, thus showing that the set of continuous functions g that yield existence to (P) is dense in the space of continuous functions on R.
A connection formula for Sturm—Liouville spectral functions
Authors: Eastham M. S. P.
Published: July 2007

This note develops a connection formula for spectral functions given in a recent paper by Gilbert and Harris.
Steady vortex in a uniform shear flow of an ideal fluid
Authors: Emamizadeh B.
Published: July 2007

This paper is concerned with the existence of maximizers for a certain non-convex energy functional, relative to a class of rearrangements of a given function. Physically, the solution represents a uniform shear flow containing a bounded vortex anomaly, in R2. The prescribed data are the rearrangement class of the vorticity field.
Homoclinic-Hopf interaction: an autoparametric bifurcation
Authors: Fečkan M. , Gruendler J.
Published: July 2007

Bifurcation of periodic and chaotic solutions is investigated for coupled perturbed autonomous ordinary differential equations (ODEs) when the first unperturbed ODE has a homoclinic solution and the second unperturbed ODE possesses a Hopf singularity.
Large-time behaviour of solutions to the dissipative nonlinear Schrödinger equation
Authors: Hayashi N. , Kaikina E. I. , Naumkin P. I.
Published: July 2007

We study the Cauchy problem for the nonlinear Schrödinger equation with dissipation

where L is a linear pseudodifferential operator with dissipative symbol ReL(ξ) ≥ C1|ξ|2/(1 + ξ2) and |L′(ξ)| ≤ C2(|ξ|+ |ξ|n) for all ξ ∈ R. Here, C1, C2 > 0, n ≥ 1. Moreover, we assume that L(ξ) = αξ2 + O(|ξ|2+γ) for all |ξ| < 1, where γ > 0, Re α > 0, Im α ≥ 0. When L(ξ) = αξ2, equation (A) is the nonlinear Schrödinger equation with dissipation ut − αuxx + i|u|2u = 0. Our purpose is to prove that solutions of (A) satisfy the time decay estimate

under the conditions that u0 ∈ Hn,0 ∩ H0,1 have the mean value

and the norm ‖u0‖Hn,0 + ‖u0‖H0,1 = ε is sufficiently small, where σ = 1 if Im α > 0 and σ = 2 if Im α = 0, and

Therefore, equation (A) is considered as a critical case for the large-time asymptotic behaviour because the solutions of the Cauchy problem for the equation ut − αuxx + i|u|p−1u = 0, with p > 3 have the same time decay estimate ‖u‖L∞ = O(t−½) as that of solutions to the linear equation. On the other hand, note that solutions of the Cauchy problem (A) have an additional logarithmic time decay. Our strategy of the proof of the large-time asymptotics of solutions is to translate (A) to another nonlinear equation in which the mean value of the nonlinearity is zero for all time.
Stability and existence of multiple periodic solutions for a quasilinear differential equation with maxima
Authors: Pinto Manuel , Trofimchuk Sergei
Published: July 2007

We study the stability of periodic solutions of the scalar delay differential equation

where f(t) is a periodic forcing term and δ,p∈R. We study stability in the first approximation showing that the non-smooth equation (*) can be linearized along some ‘non-singular’ periodic solutions. Then the corresponding variational equation together with the Krasnosel'skij index are used to prove the existence of multiple periodic solutions to (*). Finally, we apply a generalization of Halanay's inequality to establish conditions for global attractivity in equations with maxima.
Cauchy problem for the time-dependent Ginzburg–Landau model of superconductivity
Authors: Rodriguez-Bernal A. , Wang B.
Published: July 2007

The Cauchy problem for the time-dependent Ginzburg–Landau equations of superconductivity in Rd (d = 2, 3) is investigated in this paper. When d = 2, we show that the Cauchy problem for this model is well posed in L2. When d = 3, we establish the existence result of solutions for L3 initial data and the uniqueness result for L4 initial data.
A generalization of a theorem of Barron and Jensen and a comparison theorem for lower semicontinuous viscosity solutions
Authors: Ishii Hitoshi
Published: July 2007

We extend and clarify some of observations due to Barron and Jensen concerning the relation between subdifferentials and superdifferentials of a function and extend the comparison principle for semicontinuous solutions of Hamilton–Jacobi equations with convex Hamiltonians to that in infinite-dimensional Hilbert spaces.
Structure of the Fučík spectrum and existence of solutions for equations with asymmetric nonlinearities
Authors: Ben-Naoum A. K. , Fabry C. , Smets D.
Published: July 2007

Let L : dom L ⊂ L2(Ω) → L2(Ω) be a self-adjoint operator, Ω being open and bounded in RN. We give a description of the Fučík spectrum of L away from the essential spectrum. Let λ be a point in the discrete spectrum of L; provided that some non-degeneracy conditions are satisfied, we prove that the Fučík spectrum consists locally of a finite number of curves crossing at (λ, λ). Each of these curves can be associated to a critical point of the function H : x ↦ 〈|x|,x〉L2 restricted to the unit sphere in ker(L – λI). The corresponding critical values determine the slopes of these curves. We also give global results describing the Fučík spectrum, and existence results for semilinear equations, by performing degree computations between the Fučík curves.
Duality relations for nonlinear incompressible two-dimensional elasticity
Authors: Francfort G. A. , Suquet P. M.
Published: July 2007

Keller's phase-interchange relation, which computes the overall conductivity of a two-dimensional checkerboard with alternating conductivity, is revisited in the context of nonlinear incompressible elasticity. A general phase-interchange relation is obtained in a monotone setting through H-convergence and in a convex setting through variational methods. Several Keller-like applications are presented.
Enhancing ecosystem management through social-ecological inventories: lessons from Kristianstads Vattenrike, Sweden
Authors: SCHULTZ LISEN , FOLKE CARL , OLSSON PER
Published: July 2007

Environmental policy increasingly emphasizes involvement of local users and land owners in ecosystem management, but conservation planning is still largely a bureaucratic-scientific endeavour of identifying biological values for protection. Neither biological inventories nor stakeholder analyses, that tend to focus on conflicting interests, capture human resources in the landscape or the social structures and processes underlying biological conservation values. Social-ecological inventories are therefore proposed during the preparation phase of conservation projects as a means to identify people with ecosystem knowledge that practise ecosystem management. The method presented here focuses on local steward groups acting outside official management plans. In a social-ecological inventory of a river basin of southern Sweden, local steward groups, their ecosystem management activities, motives and links to other actors involved in ecosystem management were identified through interviews, participatory observations and a review of documents and other written material. Several hundred active local stewards were organized in 10 local steward groups that managed and monitored a range of ecosystem services at different spatial scales. Contributions of local stewards included on-site ecosystem management, long-term and detailed monitoring of species and ecosystem dynamics, local ecological knowledge, public support for ecosystem management and specialized networks. Two conservation projects are used to illustrate how local steward groups came together in multi-level networks and collaborated around specific conservation issues. The projects have been linked to ecosystem management at the landscape level through a flexible municipality organization, the Ecomuseum Kristianstads Vattenrike (EKV). EKV has acted as a ‘bridging organization’, coordinating and connecting many of the local steward groups to organizations and institutions at other levels. The process has been guided by social capital and shared visions for the whole landscape. The study shows that ecosystem management likely relies on multi-level collaboration and social-ecological inventories may help identify actors that are fundamental in such management systems. Social-ecological inventories should be employed in any attempt to develop and implement ecosystem management.
The instantaneous rate dependence in low temperature laboratory rock friction and rock deformation experiments
Authors: Beeler N. M. , Tullis T. E. , Kronenberg A. K. , Reinen L. A.
Published: July 2007

Earthquake occurrence probabilities that account for stress transfer and time‐dependent failure depend on the product of the effective normal stress and a lab‐derived dimensionless coefficient a. This coefficient describes the instantaneous dependence of fault strength on deformation rate, and determines the duration of precursory slip. Although an instantaneous rate dependence is observed for fracture, friction, crack growth, and low temperature plasticity in laboratory experiments, the physical origin of this effect during earthquake faulting is obscure. We examine this rate dependence in laboratory experiments on different rock types using a normalization scheme modified from one proposed by Tullis and Weeks [1987]. We compare the instantaneous rate dependence in rock friction with rate dependence measurements from higher temperature dislocation glide experiments. The same normalization scheme is used to compare rate dependence in friction to rock fracture and to low‐temperature crack growth tests. For particular weak phyllosilicate minerals, the instantaneous friction rate dependence is consistent with dislocation glide. In intact rock failure tests, for each rock type considered, the instantaneous rate dependence is the same size as for friction, suggesting a common physical origin. During subcritical crack growth in strong quartzofeldspathic and carbonate rock where glide is not possible, the instantaneous rate dependence measured during failure or creep tests at high stress has long been thought to be due to crack growth; however, direct comparison between crack growth and friction tests shows poor agreement. The crack growth rate dependence appears to be higher than the rate dependence of friction and fracture by a factor of two to three for all rock types considered.
Group velocity cones in diverging magnetic reconnection structures
Authors: Singh Nagendra
Published: July 2007

In a typical geometry of magnetic reconnection, the so‐called exhaust regions diverge out of the localized diffusion region. The diverging reconnection structure is conical in shape with its apex near the x‐line. Such conical regions have been seen in both MHD and kinetic simulations of reconnection as well as in satellite observations. We demonstrate here that depending on the reconnection regime, the cone angle of the exhaust regions found in numerical simulations and as well as in satellite observations compare well with the maximum angles of group‐velocity cones associated with the slow MHD mode, or the whistler mode, or the kinetic Alfvén wave (KAW). For each of these three reconnection regimes, we give a quantitative description of the group velocity cones. In the MHD case the cone angle is small and increases almost linearly with the plasma β < 2. In the whistler regime the cone angle is a constant of 19.5°. In the KAW regime the cone angle depends on plasma β as well as on the timescale associated with the diffusion process in the current sheet. The close agreement between the observed and simulated exhaust cone angles and the group‐velocity cone angles in all the three reconnection regimes is highly suggestive that “at least” the geometrical feature of the exhaust region is determined by the group velocity of the disturbances, which propagate out of the diffusion region.
Permeability evolution in quartz fault gouges under hydrothermal conditions
Authors: Giger Silvio B. , Tenthorey Eric , Cox Stephen F. , Fitz Gerald John D.
Published: July 2007

The permeability (k) of fine‐grained quartz aggregates were measured in situ during hot pressing (HPing) experiments to explore the evolution of fluid transport properties of fault zones during the interseismic period. Experiments were conducted at temperatures of 150°C and between 700 and 850°C, with confining and pore water pressures of 250 and 150 MPa, respectively. Significant permeability reduction was observed between 700 and 850°C, with permeability reduction rates (r= (1/t) ln (kto/kt)), ranging from approximately 6 × 10−5s−1at 700°C to a maximum of approximately 7.4 × 10−4s−1at 850°C. Permeability decreased exponentially with time, and the permeability reduction rate increased with increasing temperature, increasing differential stress, and decreasing grain size. Analysis of the permeability‐porosity relationships indicates that permeability in the simulated gouge at high temperature shuts off at a critical porosity of 0.045 ± 0.004. The presence of microstructures, such as grain interpenetration, grain shape truncation, arrays of fluid inclusions, and development of quartz overgrowths on grains, indicate that k reduction was controlled by dissolution‐precipitation creep processes. Extrapolation of the permeability reduction rates, measured in this study, to temperatures typical of the continental seismogenic regime highlights the strongly time‐dependent nature of permeability in natural fault wear products at depths of nucleation of major earthquakes. Within the recurrence time of large earthquakes, quartz‐rich fault zones in the fluid‐active midcrustal to lower continental crustal regimes can evolve from high‐permeability conduits to low‐permeability seals. Episodic changes in the fluid transport properties of faults during the interseismic period are likely to impact on the pore pressure evolution of fault wear products.
Variable fractal dimension: A major control for floc structure and flocculation kinematics of suspended cohesive sediment
Authors: Maggi Federico
Published: July 2007

While the fractal dimension of suspended flocs of cohesive sediment is known to vary with the shear rate, electrochemical properties of the sediment and environment, geometrical restructuring, and presence of organic matter, experimental data presented in this work suggest changes in fractal dimension also during floc genesis at constant sedimentological and hydraulic conditions. A power law function is proposed to describe these changes in floc fractal dimension during floc growth and is used to analyze its impact on floc structural parameters, settling velocity, and kinematics of aggregation and breakup. An analysis of this model for the fractal dimension highlights changes of approximately a factor of 2 or more in floc porosity and aggregation and breakup frequencies and of approximately 1 order of magnitude in floc excess density and settling velocity compared to values estimated with constant fractal dimension. The results from this model compare well with prior experimental data collected in situ (Khelifa and Hill, 2006; Manning and Dyer, 1999).
Removal of sulfur dioxide and formation of sulfate aerosol in Tokyo
Authors: Miyakawa T. , Takegawa N. , Kondo Y.
Published: July 2007

Ground‐based in situ measurements of sulfur dioxide (SO2) and submicron sulfate aerosol (SO42−) together with carbon monoxide (CO) were conducted at an urban site in Tokyo, Japan from spring 2003 to winter 2004. The observed concentrations of SO2 were affected dominantly by anthropogenic emissions (for example, manufacturing industries) in source areas, while small fraction of the data (<30%) was affected by large point sources of SO2 (power plant and volcano). Although emission sources of CO in Tokyo are different from those of SO2, the major emission sources of CO and SO2 are colocated, indicating that CO can be used as a tracer of anthropogenic SO2 emissions in Tokyo. The ratio of SO42− to total sulfur compounds (SOx = SO2 + SO42−) and the remaining fraction of SOx, which is derived as the ratio of the linear regression slope of the SOx‐CO correlation, is used as measures for the formation of SO42− and removal of SOx, respectively. Using these parameters, the average formation efficiency of SO42− (i.e., amount of SO42− produced per SO2 emitted from emission sources) are estimated to be 0.18 and 0.03 in the summer and winter periods, respectively. A simple box model was developed to estimate the lifetime of SOx. The lifetime of SOx for the summer period (26 h) is estimated to be about two times longer than that for the winter period (14 h). The seasonal variations of the remaining fraction of SOx, estimated formation efficiency of SO42−, and lifetime of SOx are likely due to those of the boundary layer height and photochemical activity (i.e., hydroxyl radical). These results provide useful insights into the formation and removal processes of sulfur compounds exported from an urban area.
Effects of bias correction on precipitation trend over China
Authors: Ding Yongjian , Yang Daqing , Ye Baisheng , Wang Ninglian
Published: July 2007

Long‐term monthly climatic data during 1951–1998 at 627 meteorological stations over China have been analysed in this study to examine the impact of bias corrections on monthly and yearly precipitation trends. The impacts of bias corrections on trends depended on the gauge catch efficiency and changes of wind speed, temperature, snow percentage, and number of trace and measurable precipitation days. Trends of corrected and measured monthly and yearly precipitation have similar regional patterns over China, although the trends are different quantitatively over some regions. Precipitation trends in summer months are generally higher than winter season because of high precipitation in summer and low in winter. For instance, trends in January and July are −8 to +20 mm/10a and −37 to +55 mm/10a over China for the measured data during 1951–1998, respectively. Bias corrections enhance monthly precipitation trends in every month by about 7 to 18%, leading to an 8% overall enhancement of absolute yearly precipitation trends over China. For the individual stations, the difference in corrected and measured annual precipitation trends varies from −4.1 to +19.0 mm/10a (−5.0 to +1.7%/10a) across China. It is important to note that bias corrections can change precipitation trend. Our analyses show that bias corrections have changed monthly and yearly precipitation trend direction from positive to negative over some regions in China. The trend changes reported here are large enough to affect regional climate and hydrology analyses, particularly over cold regions. More efforts are needed to quantify the impact of bias corrections on precipitation change analyses over other large countries and regions.
First global distributions of nitric acid in the troposphere and the stratosphere derived from infrared satellite measurements
Authors: Wespes Catherine , Hurtmans Daniel , Herbin Hervé , Barret Brice , Turquety Solène , Hadji‐Lazaro Juliette , Clerbaux Cathy , Coheur Pierre‐François
Published: July 2007

Global distributions of nitric acid (HNO3) partial columns in the troposphere and the stratosphere are shown for the first time. HNO3 vertical profiles are retrieved from a set of high‐resolution infrared spectra, measured by the nadir‐viewing Interferometric Monitor for Greenhouse Gases (IMG) instrument onboard the ADEOS satellite. Ten successive days of IMG operation in April 1997 are analyzed, yielding quasi‐global distributions. We show that the IMG measurements contain between 0.7 and 1.8 independent pieces of information on the HNO3 vertical distribution; the extent of which depends on the observed scene. In the tropics and the midlatitudes, tropospheric and stratospheric columns can be separated, whereas, in the colder polar regions, the total column is the most relevant quantity. A detailed error budget reveals that the accuracy on the profile measurements ranges from 5–15% in the stratosphere to about 20–30% in the middle troposphere, and as much as 60% in the lowermost troposphere where the measurements are less sensitive. The global distributions of tropospheric and stratospheric partial columns are presented and discussed. In the stratosphere we measure higher columns at both poles than in the intertropical belt, as expected for the period in April analyzed here. In the troposphere, the zonal distributions show elevated values nearby NOx source regions, such as central Europe, the Eastern coast of the United States, and the North‐West of India. Typical profiles with mixing ratios up to 2 ppbv in the boundary layer and 1 ppbv in the free troposphere are identified. These novel results indicate a possible role of HNO3 in the long‐range transport of active nitrogen and open promising perspectives for future space missions dedicated to atmospheric chemistry.
Wind induced oscillator dynamics in the Black Sea revealed by Lagrangian drifters
Authors: Ivanov Leonid M. , Melnichenko Oleg V. , Collins Curtis A. , Eremeev Valery N. , Motyzhev Sergey V.
Published: July 2007

Lagrangian drifter observations of the Black Sea circulation between 2002 and 2003 show six transitions between two meta‐stable states representing single gyre structures centered in either the western or eastern sub‐basin of the Black Sea, respectively. The major mechanisms driving such an oscillator dynamics are Ekman pumping for the eastern sub‐basin, and most likely a resonance excitation for the western sub‐basin. The sea strongly amplifies the wind responses of 120‐day periodicity. Data analysis demonstrates that two‐gyre structure (“Knipovich spectacles”) was a transient between the states. Residence time for the sea to occupy either state is mainly determined by the instability of the gyres, wind variability and, probably, variations in the pycnocline. This behavior is a manifestation of a bimodal dynamical regime which affects the long‐term (climatic), large‐scale transport and mixing of bio‐geochemical substances.
Prologue: Development of English Literacy in Spanish-Speaking Children: Transforming Research Into Practice
Authors: Garcia Gil Narro , McCardle Peggy , Nixon Stephanie M.
Published: July 2007

Purpose

The purpose of the present article is to provide the background for the clinical forum contained in this issue, which showcases prereading and reading development research that was conducted with Spanish-speaking children who were English language learners.

Method

We focus on the articles presented in this clinical forum and provide the background for the research.

Implications

There is a need for further educational research to ensure that practitioners achieve literacy for all children.
Coupling term derivation and general implementation of state-specific multireference coupled cluster theories
Authors: Evangelista Francesco A. , Allen Wesley D. , Schaefer Henry F.
Published: July 2007

Simple closed-form expressions are derived for the “same vacuum” renormalization terms that arise in state-specific multireference coupled cluster (MRCC) theories. Explicit equations are provided for these coupling terms through the triple excitation level of MRCC theory, and a general expression is included for arbitrary-order excitations. The first production-level code (PSIMRCC) for state-specific and rigorously size-extensive Mukherjee multireference coupled cluster singles and doubles (MkCCSD) computations has been written. This code is also capable of evaluating analogous Brillouin-Wigner multireference energies (BWCCSD), including a posteriori size-extensivity corrections. Using correlation-consistent basis sets (cc-pVXZ, X=D,T,Q), MkCCSD and BWCCSD were tested and compared on two classic multireference problems: (1) the dissociation potential curve of molecular fluorine (F2) and (2) the structure and vibrational frequencies of ozone. Comparison with experimental data shows that the Mukherjee method is generally superior to the Brillouin-Wigner theory in predicting energies, structures, and vibrational frequencies. Particularly accurate results for F2 are obtained by applying the MkCCSD method with localized molecular orbitals. Although the MkCCSD theory greatly improves upon single-reference CCSD for the geometric parameters and a1 vibrational frequencies of ozone, the antisymmetric stretching frequency ω3(b2) remains pathological and cannot be properly treated without the inclusion of connected triple excitations. Finally, preliminary multireference MkCCSD results are reported for the singlet-triplet splittings in ortho-, meta-, and para-benzyne, coming within 1.5kcalmol−1 of experiment in all cases.
Observation of ultrahigh density InGaN quantum dots
Authors: Tsai H. L. , Wang T. Y. , Yang J. R. , Wang T. C. , Hsu J. T. , Shiojiri M.
Published: July 2007

High density InGaN quantum dots (QDs) grown on an underlying GaN layer that was partially masked with SiNx nanocrystals were investigated by cross-sectional high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy, and energy dispersive x-ray spectroscopy. The layer of SiNx masks appeared as a dark line in the HAADF-STEM images, and from the thickness of that dark line, the height of the masks was roughly estimated to be less than 2nm. The InGaN QDs appeared as bright triangles in the HAADF-STEM images. The QDs can be regarded as nanosized island crystals consisting of {101¯1} sidewalls, with a height of several nanometers. The lattices in the InGaN crystals were strained as compared to the underlying and the capping GaN lattices and contacted them coherently.
Molecular potential energy surfaces constructed from interpolation of systematic fragment surfaces
Authors: Collins Michael A.
Published: July 2007

A systematic method for approximating the ab initio electronic energy of molecules from the energies of molecular fragments has previously been presented. Here it is shown that this approach provides a feasible, systematic method for constructing a global molecular potential energy surface (PES) for reactions of a moderate-sized molecule from the corresponding surfaces for small molecular fragments. The method is demonstrated by construction of PESs for the reactions of a hydrogen atom with propane and n-pentane.
Why does the B3LYP hybrid functional fail for metals?
Authors: Paier Joachim , Marsman Martijn , Kresse Georg
Published: July 2007

The B3LYP hybrid functional has shown to successfully predict a wide range of molecular properties. For periodic systems, however, the failure to attain the exact homogeneous electron gas limit as well as the semiempirical construction turns out to be a major drawback of the functional. We rigorously assess the B3LYP functional for solids through calculations of lattice parameters, bulk moduli, and thermochemical properties (atomization energies and reaction energies). The theoretical lattice constants overestimate the experimental ones by approximately 1%, and hence behave similarly to the PBE gradient-corrected exchange-correlation functional. B3LYP atomization energies of solids are drastically worse than those of nonempirical hybrid Hartree-Fock/density functionals (HF/DFT) such as PBE0 and HSE03. These large errors can be traced back to the lack of a proper description of “free-electron-like” systems with a significant itinerant character (metals and small gap semiconductors). Similar calculations using the popular semiempirical B3PW91 hybrid functional, which fulfills the uniform electron gas limit, show a clear improvement over B3LYP regarding atomization energies. Finally, theoretical values for heats of formation for both the B3LYP as well as the B3PW91 functionals are presented. These document a most likely fortuitously good agreement with experiment for the B3LYP hybrid functional.
Effect of film thickness and laser energy density on the microstructure of a-GaAs films after excimer laser crystallization
Authors: Pirzada Daniel , Trivedi Pankaj , Field David , Cheng Gary J.
Published: July 2007

A KrF excimer laser with 30 ns pulse duration is used for crystallization of a-GaAs grown on silicon substrate using molecular beam epitaxy technique. The effect of laser energy density and film thickness on grain morphology has been studied. Scanning electron microscopy and high-resolution electron backscatter diffraction have been used to study the texture and microstructure evolution during the crystallization of initially amorphous GaAs thin films. The integrated information on grain size distribution, preferred orientation, and nature of grain boundaries provides useful information to postulate the mechanism of grain growth and the likely role of different contributing parameters in the evolution of final texture under the highly transient processing conditions prevailing during the short laser irradiation. The texture ranges from weak ⟨111⟩ fiber texture to strong ⟨100⟩ texture depending on film thickness and laser influence. The grain structure and texture development are discussed based on the three melting regimes: (1) partial meting regime; (2) complete melting regime; and (3) near-complete melting regime.
Volume conservation in bulk metallic glasses
Authors: Ma D. , Stoica A. D. , Wang X.-L.
Published: July 2007

The authors report that the excess molar volumes of mixing for ∼30 metalloid-free bulk metallic glasses (BMGs) are essentially zero, indicating that the original volumes of “mechanically mixed” constituent elemental metals are conserved after glass formation. This is attributed to the lack of solute-solute bonds and the ideal-mixing nature of solvent-solute bonding upon amorphization. The hard-sphere atomic packing fractions of most of these BMGs are found to be ∼0.74, comparable to the maximum packing efficiency for close-packed structures. These findings present a different perspective for understanding amorphous structures.
Effects of shock-breakout pressure on ejection of micron-scale material from shocked tin surfaces
Authors: Zellner M. B. , Grover M. , Hammerberg J. E. , Hixson R. S. , Iverson A. J. , Macrum G. S. , Morley K. B. , Obst A. W. , Olson R. T. , Payton J. R. , Rigg P. A. , Routley N. , Stevens G. D. , Turley W. D. , Veeser L. , Buttler W. T.
Published: July 2007

This effort investigates the relation between ejecta production and shock-breakout pressure (PSB) for Sn shocked with a Taylor shockwave (unsupported) to pressures near the solid-on-release/partial melt-on-release phase transition region. The shockwaves were created by detonation of high explosive (HE) PBX-9501 on the front side of Sn coupons. Ejecta production at the backside or free side of the Sn coupons was characterized through use of piezoelectric pins, optical shadowgraphy, x-ray attenuation radiography, and optical-heterodyne velocimetry. Ejecta velocities, dynamic volume densities, and areal densities were then correlated with the shock-breakout pressure of Sn surfaces characterized by roughness average of Ra=16 μin or Ra=32 μin.
Polyacrylonitrile as a gate dielectric material
Authors: Hsu Hui-Lin , Yang Wei-Chang , Lee Ya-Lien , Yew Tri-Rung
Published: July 2007

A soluble organic material, polyacrylonitrile (PAN), was investigated for its feasibility of gate dielectric applications. The solution-processed PAN was spin coated in air. Results show that leakage current density as low as 0.3nA∕cm2 for 50nm PAN dielectrics could be achieved via process optimization. Functional transistor characteristics were achieved in air for the implementation of PAN in organic thin-film transistors using pentacene or poly(3-hexylthiophene) as a semiconductor material.
Apparatus to study the onset of free convection about vertical and inclined hot wires
Authors: Giaretto Valter , Miraldi Elio , Torchio Marco F.
Published: July 2007

This article describes a methodology and an apparatus used to evaluate the onset time of free convection in hot-wire experiments. The evaluation of the onset time is useful to obtain a measurement interval that is suitable to estimate the thermal properties of a fluid. If a pure conduction regime is present, the hot-wire temperature increment versus time is a straight line in a semilog plot, whereas the convection effect induces a deviation from this trend. An algorithm based on the F test is proposed to evaluate the onset time of free convection. The experimental facility has the particular feature of allowing an easy change of the hot-wire inclination angle up to 118.3mrad. The wire is kept in a tilted position by a permanent horseshoe magnet, and the tilting angle from the vertical is measured by a theodolite. Some testing results using water are discussed for vertical and inclined wires. A good agreement between the experimental onset times and the theoretical ones is found in the case of a vertical wire.
Versatile platform for creating gradient combinatorial libraries via modulated light exposure
Authors: Berry Brian C. , Stafford Christopher M. , Pandya Mayur , Lucas Leah A. , Karim Alamgir , Fasolka Michael J.
Published: July 2007

This article details the design, construction, and operation of flexible system that modulates light exposure for the purpose of fabricating continuous and discrete gradient combinatorial libraries. Designed for versatility, the device combines “off the shelf” components, modular accessories, and flexible computer control, so that it can be used for a variety of combinatorial research applications. Salient aspects and capabilities of the instrument are illustrated through two practical examples. The first case demonstrates how user defined exposure functions can be used to create continuous surface energy gradient libraries with a linear profile. The second example illustrates the creation of continuous and discrete libraries for mapping exposure-property functions in a photocurable polymer system.
Solidification contraction-free synthesis for the Yb0.15Co4Sb12 bulk material
Authors: Geng H. Y. , Ochi S. , Guo J. Q.
Published: July 2007

The solidification contraction and feeding ability of Yb partially filled CoSb3 skutterudite alloys were studied in this letter. It is found that the pore formation was mainly due to the large solidification contraction during the L+CoSb→CoSb2 peritectic phase transition and the primary dendrite networks. Homogeneous and full density Yb0.15Co4Sb12 bulk material was synthesized directly from the peritectic phase transition L+CoSb2→CoSb3 by controlling the melting temperature and starting materials. The result of thermoelectric property measurement from room temperature to 500°C shows that the thermoelectric dimensionless figure of merit reaches to the maximum of 0.7 at 400°C.
Time tuning of ferroelectric film varactors under pulse voltages
Authors: Kozyrev Andrey B. , Osadchy Vitaly N. , Kosmin Dmitry M. , Tumarkin Andrey V. , Kaydanova Tatiana , Ginley David
Published: July 2007

Significant difference in the capacitance tunability of paraelectric state ferroelectric capacitors under dc and pulse voltages is demonstrated. Along with a fast tuning (τ<10ns) the slow relaxation processes (τ⩾100s) responsible for up to ∼30% variation of the capacitance were observed. The observed effect is a main obstacle for application of paraelectric state ferroelectrics on microwaves.
Positronium annihilation and pore surface chemistry in mesoporous silica films
Authors: He Chunqing , Oka Toshitaka , Kobayashi Yoshinori , Oshima Nagayasu , Ohdaira Toshiyuki , Kinomura Atsushi , Suzuki Ryoichi
Published: July 2007

Lifetimes of ortho-positronium in mesoporous silica films were measured before and after surface trimethylsilylation of –OH groups. Variations of positronium lifetimes in the mesopores upon the surface modification indicate that the interaction between positronium and the pore surface is weakened in the pores, whose surface is covered with –CH3 groups, in comparison with those covered with –OH groups. This is consistent with the authors’ previous observation that positronium slowing down is less efficient in the pores covered with –CH3 groups. The present work demonstrates that in the porosimetric application of positron annihilation lifetime spectroscopy, the interaction between positronium and the pore surface has to be properly taken into consideration.
Pattern formation in martensitic thin films
Authors: Shu Y. C. , Yen J. H.
Published: July 2007

Pattern formation in martensitic materials refers to the accommodation problem of how to mix martensitic variants coherently to minimize the strain energy. A framework motivated by energy-minimizing multirank laminated patterns is proposed to study this problem in martensitic films. It is found that the interfaces between the variants of martensite can be quite different in thin films than in bulk materials, and they typically have a simpler structure. Various intriguing and fascinating self-accommodation patterns are predicted for martensitic thin films with different orientations. The results are in good agreement with the Bhattacharya-James thin-film theory [K. Bhattacharya and R. D. James, J. Mech. Phys. Solids 47, 531 (1999)] as well as with experimental observations.
Analysis for crystal structure of Bi(Fe,Sc)O3 thin films and their electrical properties
Authors: Yasui Shintaro , Uchida Hiroshi , Nakaki Hiroshi , Nishida Ken , Funakubo Hiroshi , Koda Seiichiro
Published: July 2007

Thin films of Bi(Fe1−xScx)O3 (BFSO) system were fabricated on (111)Pt∕TiO2∕SiO2∕(100)Si substrates by chemical solution deposition to improve the electrical resistivity by substituting electrically unstable Fe3+ cations for stable Sc3+ cations. A single phase of perovskite was obtained in the range of x=0–0.30, in which selective replacement of Fe3+ and Sc3+ was confirmed in x=0–0.15 by using Raman measurement. The leakage current density of the BFSO films was reduced by increasing x. A well-saturated polarization–electric field hysteresis loop was obtained for BFSO films with x=0.15, showing remanent polarization of approximately 35μC∕cm2.
Cell encapsules with tunable transport and mechanical properties
Authors: Luo Dawei , Pullela Srinivasa Rao , Marquez Manuel , Cheng Zhengdong
Published: July 2007

We utilized a microfluidic device with hydrodynamic flow focusing geometry to produce uniform agarose droplets in the range of 50 to 110 μm. The transport property of the thermally gelled particles was tailored by layer-by-layer (LBL) polyelectrolytes coating on the surface and was measured via the release rates of Rhodamine B. The mechanical strength of the capsules was further enhanced by a coating of silica nano-particles in addition to polyelectrolyte coatings. We demonstrated that yeast cells can be successfully encapsulated into agarose capsules.
Telomere length is paternally inherited and is associated with parental lifespan
Authors: Njajou Omer T. , Cawthon Richard M. , Damcott Coleen M. , Wu Shih-Hsuan , Ott Sandy , Garant Michael J. , Blackburn Elizabeth H. , Mitchell Braxton D. , Shuldiner Alan R. , Hsueh Wen-Chi
Published: July 2007

Telomere length (TL) is emerging as a biomarker for aging and survival. To evaluate factors influencing this trait, we measured TL in a large homogeneous population, estimated the heritability (h
2
), and tested for parental effects on TL variation. Our sample included 356 men and 551 women, aged 18–92 years, from large Amish families. Mean TL in leukocytes was measured by quantitative PCR (mean: 6,198 ± 1,696 bp). The h
2
of TL was 0.44 ± 0.06 (
P
< 0.001), after adjusting for age, sex, and TL assay batch. As expected, TL was negatively correlated with age (
r
= −0.40;
P
< 0.001). There was no significant difference in TL between men and women, consistent with our previous findings that Amish men lived as long as Amish women. There was a stronger and positive correlation and association between TL in the offspring and paternal TL (
r
= 0.46,
P
< 0.001; β = 0.22,
P
= 0.006) than offspring and maternal TL (
r
= 0.18,
P
= 0.04; β = −0.02,
P
= 0.4). Furthermore, we observed a positive correlation and association between daughter's TL and paternal lifespan (
r
= 0.20,
P
< 0.001; β = 0.21,
P
= 0.04), but not between daughter's TL and maternal lifespan (
r
= −0.01, β = 0.04; both
P
= not significant). Our data, which are based on one of the largest family studies of human TL, support a link between TL and aging and lifespan and suggest a strong genetic influence, possibly via an imprinting mechanism, on TL regulation.
IL-6-dependent and -independent pathways in the development of interleukin 17-producing T helper cells
Authors: Kimura Akihiro , Naka Tetsuji , Kishimoto Tadamitsu
Published: July 2007

CD4
+
T cells producing IL-17 [T helper (Th)17], as distinct from Th1 or Th2 cells, have recently been shown to be associated with autoimmunity, but it is not entirely clear how Th17 cells are generated from naïve T cells. We demonstrate here that IL-6, but not TNF-α or IL-1β, can, in combination with TGF-β, induce Th17 cell generation from naïve T cells and inhibit TGF-β-induced Foxp3 expression. Moreover, conditioned medium from lipopolysaccharide-stimulated bone marrow-derived dendritic cells (DCCM) can induce IL-17 production in naïve T cells. Interestingly, IL-17 was produced by DCCM even with the addition of anti-gp130 antibody or DCCM from IL-6 KO mice. The combination of IL-6 and TGF-β could maintain activation of signal transducer and activator of transcription (Stat)3, but not of Stat1. IL-27 or IFN-γ suppressed the induction of Th17 cells by TGF-β plus IL-6 and maintained Stat1 activation under these conditions. In contrast, both Stat1 and Stat3 remained to be activated in naïve T cells cultured with DCCM. These findings represent a different basis for Th17 differentiation from naïve T cells.
Endocytic Down-Regulation of ErbB2 Is Stimulated by Cleavage of Its C-Terminus
Authors: Lerdrup Mads , Bruun Silas , Grandal Michael V. , Roepstorff Kirstine , Kristensen Malene M. , Hommelgaard Anette M. , van Deurs Bo
Published: July 2007

High ErbB2 levels are associated with cancer, and impaired endocytosis of ErbB2 could contribute to its overexpression. Therefore, knowledge about the mechanisms underlying endocytic down-regulation of ErbB2 is warranted. The C-terminus of ErbB2 can be cleaved after various stimuli, and after inhibition of HSP90 with geldanamycin this cleavage is accompanied by proteasome-dependent endocytosis of ErbB2. However, it is unknown whether C-terminal cleavage is linked to endocytosis. To study ErbB2 cleavage and endocytic trafficking, we fused yellow fluorescent protein (YFP) and cyan fluorescent protein (CFP) to the N- and C-terminus of ErbB2, respectively (YFP-ErbB2-CFP). After geldanamycin stimulation YFP-ErbB2-CFP became cleaved in nonapoptotic cells in a proteasome-dependent manner, and a markedly larger relative amount of cleaved YFP-ErbB2-CFP was observed in early endosomes than in the plasma membrane. Furthermore, cleavage took place at the plasma membrane, and cleaved ErbB2 was internalized and degraded far more efficiently than full-length ErbB2. Concordantly, a C-terminally truncated ErbB2 was also readily endocytosed and degraded in lysosomes compared with full-length ErbB2. Altogether, we suggest that geldanamycin leads to C-terminal cleavage of ErbB2, which releases the receptor from a retention mechanism and causes endocytosis and lysosomal degradation of ErbB2.
Correcting for gene-specific dye bias in DNA microarrays using the method of maximum likelihood
Authors: Kelley Ryan , Feizi Hoda , Ideker Trey
Published: July 2007

Motivation: In two-color microarray experiments, well-known differences exist in the labeling and hybridization efficiency of Cy3 and Cy5 dyes. Previous reports have revealed that these differences can vary on a gene-by-gene basis, an effect termed gene-specific dye bias. If uncorrected, this bias can influence the determination of differentially expressed genes.

Results: We show that the magnitude of the bias scales multiplicatively with signal intensity and is dependent on which nucleotide has been conjugated to the fluorescent dye. A method is proposed to account for gene-specific dye bias within a maximum-likelihood error modeling framework. Using two different labeling schemes, we show that correcting for gene-specific dye bias results in the superior identification of differentially expressed genes within this framework. Improvement is also possible in related ANOVA approaches.

Availability: A software implementation of this procedure is freely available at http://cellcircuits.org/VERA

Contact:  rmkelley@ucsd.edu

Supplementary information: Supplementary data are available at Bioinformatics online.