bluuebunny/crossref_metadata_2025 huggingface dataset:
Elektronenspektroskopie für Chemische Analysen (ESCA) im industriellen Routinebetrieb
Authors: Albers Th.
Published: July 2007

Eine neue Generation von ESCA‐Systemen wird vorgestellt. Es entspricht modernen industriellen Anforderungen in Bezug auf Bedienungskomfort und Automatisierbarkeit. Es ist ausgestattet mit modernen Servicekonzepten, Internetanbindung und einer Systemsteuerung, die sich um Vakuum, Kühlung und alle weiteren Aufgaben neben der eigentlichen Messung kümmert. Die Qualität der Analytik steht reinen Forschungssystemen nicht nach. Berührungsängste vor dem industriellen, routinemäßigen Einsatz von ESCA als Standardmethode sollten damit endgültig der Vergangenheit angehören.
Charakterisierung von Glas und Glasbeschichtung mittels oberflächensensibler Sondenverfahren
Authors: Scholz Th. , Haase J.
Published: July 2007

Die dargestellten Beispiele der Oberflächen‐ und Mikrobereichsanalyse an Gläsern zeigen, daß die physikalisch orientierten Sondenverfahren praktikabel in den Bereichen Entwicklung, Prozeßkontrolle und Fehleranalyse sind. Aufgrund der für diese Untersuchungen erforderlichen gerätetechnischen Ausstattung und der notwendigen fachlichen und meßtechnischen Erfahrung nutzen eine wachsende Zahl von Glas‐ und Beschichtungsfachleuten externe High Tech Dienstleistungslaboratorien.
Titannitrid als gasabgabereduzierende Schicht auf Edelstahl
Authors: Keutel Karola , Edelmann Christian , Fuchs Henning , Mecke Hubert
Published: July 2007

Unter der Verwendung eines neuen Beschichtungsverfahrens, dem modifizierten Puls‐Arc‐Verfahren werden TiN‐Schichten auf Edelstahl abgeschieden. Die Wirkung einer Titannitridschicht auf die Gasabgabestromdichte des Edelstahls wird untersucht und dargestellt. Messungen an unbeschichtetem Edelstahl und mit Titannitrid beschichtetem Edelstahl, bei dem das DC‐Arc‐Verfahren angewendet wurde, werden als Vergleich zur Bestimmung des Gasabgabeverhaltens herangezogen und ermöglichen dadurch, Aussagen über die Reduktion der Gasabgaberäte zu treffen.
Völlig ölfreie neue Vorvakuumpumpe für saubere Anwendungen
Authors: Bahnen R.
Published: July 2007

In der letzten Zeit geht überall dort, wo trockenes Vorvakuum benötigt wird und saubere Gase gepumpt werden, der Trend hin zu preiswerten Vorvakuumpumpsystemen. Diese ersetzen die seit langer Zeit in der Halbleiterindustrie erprobten trockenen Prozeßpumpen, welche für einfache Anwendungen zu aufwendig und zu teuer sind.

Um eine robuste, preiswerte und zuverlässige trockenverdichtende Vorvakuumpumpe zur Verfügung zu stellen, wurde die altbekannte Technologie der Kolbenkompressoren an die vakuumtechnischen Anforderungen angepaßt. Das daraus resultierende Produkt ist 4stufig in der Lage, 3 − 4 × 10−2 mbar zur Verfügung zu stellen.

Alle gasfördernden Schöpfräume sind vollständig trocken, und die im trocken abgedichteten Getrieberaum befindlichen fettgeschmierten Lager sind zusätzlich nochmals gedichtet. Die Wahl einer besonderen Ventilgeometrie und reibungsarmer Beschichtungswerkstoffe resultiert in einer langlebigen, robusten Maschine, welche auch Störfälle, wie z. B. gebrochene Wafer, überstehen kann.

Anwendungsgebiete sind zum Beispiel Load‐Lock‐Kammern, Analyseninstrumente und vielfältige Einsätze in der Forschung.
Flache Bildschirme — Ein Überblick
Authors: Reuschling R.
Published: July 2007

During the recent years, flat screens have become a part of our modern life. Despite of their quite complex technology, they have been made a mass product, whose most advanced technology is integrated into laptop computers. After a brief description of basic function, an overview of the involved processes and the relevant equipment is given.
Nanotribologie: Messung von mechanischen Eigenschaften im Sub‐Mikrometer‐Bereich
Authors: Hangen Ude D.
Published: July 2007

Hardness of a material describes the resistance of a material under indentation by a solid body. The vickers hardness [1] is determined by loading a diamond pyramid with a known force that is in contact with a specimen. The length of the diagonal of the remaining indent is used to calculate the contact area. The ratio of force and contact area is the vickers hardness. The abilities of modern technique of measurement replace the optical analysis of each indent by calculating the hardness from force and displacement recorded during the indent.

Nano‐hardness measurements now can be used to determine the mechanical properties of thin films and structures in the range from less than 10 nm to 1μm. Hardness can be measured with very small indentations, which could not be analyzed according to vickers. Time dependent properties as creep and viscose flux of material can be checked on sub‐micron scale. The technique of nano‐hardness measurements is comparable to the universal hardness test [2] for metals, whose minimum indentation depth of h = 0.2 μm still is too big for many applications. Combined with an atomic force microscope (AFM) the presented technique is capable image the area of interest before and after testing. Mechanical properties like friction‐constants and wear can be measured quantitatively. The indenter can be used as a micro‐machining tool with high precision as well.
Mechanical Stress in Vapour Deposited Thin Films
Authors: Pulker Hans K.
Published: July 2007

The goal of this paper was to review the problem of mechanical stresses in thin films. Particularly the origin of tensile as well as compressive intrinsic stresses and their semi‐quantitative mathematical treatments are discussed.
Dünnschichtverdampfer in der thermischen Trenntechnik
Authors: Kaiser Bernhard , Kranz Michael
Published: July 2007

So wertvoll Dünnschichtverdampfer für die thermische Verfahrenstechnik sind, so schwierig ist ihre Dimensionierung und Vorausberechenbarkeit. Trotz vieler Untersuchungen fanden sich mathematische Beschreibungen stets nur für sehr begrenzte Gültigkeitsbereiche. Für die Auslegung von Dünnschichtverdampfern ist man gezwungen auf umfangreiche Erfahrungswerte zurückzugreifen. Ohne Technikumsversuche kommt man jedoch meistens nicht aus.
Elektrische Isolation mit Aluminiumoxid
Authors: Mayer Helmut , Heinicke Erhard
Published: July 2007

In diesem Beitrag wird über Keramik‐Metall‐Verbindungen berichtet, die in der Elektrotechnik als Strom‐ und Spannungsdurchführungen verwendet werden. Der Anwender erhält Auskunft über die Auswahl Kriterien geeigneter Werkstoffe und spezielle Konstruktionsmerkmale solcher Produkte. An einigen Beispielen wird ihre Anwendungsbreite demonstriert.
Heliumlecksuche unter extremen Prüfbedingungen
Authors: Schröder Gerald , Pauly Fred , Filho João da Cruz Payão
Published: July 2007

Unter den bekannten Lecksuchverfahren hat sich die Dichtheitsprüfung mit Helium als Spürgas auf Grund ihrer hohen Empfindlichkeit und vielseitigen Anwendungsmöglichkeit als universelles Verfahren in der industriellen Fertigung und im Forschungsbereich etabliert. Es gibt verschiedene Prüfvarianten, die standardmäßig bei einem Differenzdruck von Δp = 1 bar und bei Raumtemperatur durchgeführt werden. Wenn aber in Sonderfällen eine Aussage zur Dichtheit eines Bauteils unter besonderen Betriebsbedingungen erforderlich ist, muss hierfür ein spezieller Prüfaufbau konzipiert werden.

Im Bericht werden zwei Prüfungen unter extremen Prüfbedingungen mit den dazu erforderlichen Prüfaufbauten vorgestellt.

Im ersten Fall wurden sowohl Aluminium/Edelstahl — Reibschweißverbindungen als auch Rohr‐Klemmringverschraubungen (Fa. SWAGELOK®) bei den geforderten außergewöhnlichen Betriebsbedingungen von −196 °C und 10 bar Überdruck auf Dichtheit getestet und für spezielle Anwendungen qualifiziert. Dazu wurden die Testobjekte in einen Vakuumbehälter eingebaut, komplett in flüssigen Stickstoff eingetaucht und mit Druck beaufschlagt. Über einen an den Vakuum‐Rezipienten angeschlossenen Helium‐Leckdetektor konnte dann die integrale Helium‐Leckagerate direkt bestimmt werden. Beide Verbindungsarten erfüllten die gestellten Anforderungen und wiesen keine Leckageraten im Bereich > 10−9 mbar · l · s−1 auf.

Im zweiten Fall wurden Untersuchungen zum Dichtverhalten von Rohr‐Steckverbindungen für die Gaszuführung an Hochtemperatur‐Brennstoffzellen unter den späteren Betriebsbedingungen, d.h. bei 950 °C und einem Differenzdruck von 200 mbar, durchgeführt. Die Messungen ergaben Leckageraten bei 950 °C im Bereich von 10−2 bis 10−3 mbar · l · s−1. Die Versuche haben gezeigt, dass die Steckverbindungen für einen Einsatz bei 950 °C geeignet sind. Die Leckagerate läßt sich aber durch Veränderung von Spaltbreite und Oberflächengüte noch weiter herabsetzen.
Pumping speed measurement of turbomolecular pumps by a quasistationary pump‐down method
Authors: Jitschin W.
Published: July 2007

The pumping speed of a turbomolecular pump is usually measured by injecting a stationary known gas flow via a standardised test dome into the pump and measuring the equilibrium pressure in the test dome. The ratio of gas throughput and pressure is just the pumping speed. In practice, the pressure can be conveniently and accurately measured, whereas the convenient and accurate throughput measurement is a challenging experimental problem. The present paper reports on a new method for measuring the pumping speed in which the throughput is generated by the pumping down of a vessel via an orifice. From the decrease of vessel pressure with time, and from known vessel volume, the throughput can be directly and accurately derived. Exploring measurements by the new method in fact give high accuracy, systematical error sources are practically negligible.
Zur Kennlinienstabilität von Seitenkanalverdichtern About the stability of the characteristic curves of side channel compressors
Authors: Surek D.
Published: July 2007

Im Gegensatz zu radialen und axialen Turboverdichtern verfügen Seitenkanalverdichter über stabile Betriebskennlinien im gesamten Betriebsbereich. Diese für den Betriebseinsatz von Seitenkanalverdichtern vorteilhafte Eigenschaft wurde bisher entgegengenommen, ohne nach den Ursachen dafür zu fragen. Da stabile Betriebskennlinien von Turbomaschinen für die Kennfelderweiterung im Teillastbereich angestrebt und von vielen Anwenderbereichen gefordert werden, sollen im folgenden Beitrag die Ursachen für diese Erscheinung in Seitenkanalverdichtern ermittelt werden, mit dem Ziel, die dafür verantwortlichen Strömungsstrukturen auch in anderen Verdichterbauarten zu nutzen, um den zulässigen Betriebsbereich zu erweitern. Es muß auch die Frage beantwortet werden, ob Seitenkanalverdichterstufen in der Lage sind, bei Kopplung mit Stufen anderer Verdichterbauarten der kombinierten Verdichtereinheit eine stabile Kennlinie aufzuprägen. Wenn Seitenkanalverdichter dazu in der Lage sind, könnten Erweiterungen der Lage sind, könnten Erweiterungen der Betriebsbereiche von Turboverdichtern mit Seitenkanalverdichterendstufen ohne Pumpgrenze erreicht werden.
Winter survival of pea, faba bean and white lupin cultivars in contrasting Italian locations and sowing times, and implications for selection
Authors: ANNICCHIARICO P. , IANNUCCI A.
Published: July 2007

Increasing grain legume yields via autumn sowing requires winter-hardy material. Forty-nine pea, 24 faba bean and 11 white lupin cultivars recently released by 29 breeding institutions worldwide were sown in autumn 2002 at Lodi (northern Italy) and Foggia (southern Italy) on two different dates at each location, with the objective of assessing the winter survival of species and cultivars, its consistency across locations and sowing times, its relationship with grain yield and various morphophysiological traits and the implications for selection. The winter seasons were representative for the sites and had 54 frost days and −7·3°C absolute minimum temperature in Lodi, and 8 frost days and −3·4°C absolute minimum temperature in Foggia. The species differed in optimal sowing time at each location. Mild winter temperatures, preventing a sufficient hardening against late frosts, led to higher proportions of plants killed over winter in Foggia than in Lodi (0·17 v. 0·12 for pea; 0·20 v. 0·16 for faba bean; 0·34 v. 0·11 for lupin). Variation in winter mortality was much larger within species than among species. Winter mortality and grain yield of cultivars were inversely correlated (r=−0·49, −0·43 and −0·74 for entry means over locations of pea, faba bean and lupin, respectively). The consistency across environments of genotype winter mortality, estimated by genetic correlations, was high across sowing times and low across locations for faba bean, moderate across sowing times and fairly low across locations for pea, and always fairly high for lupin. A visual cold tolerance score was always related to better winter survival. Winter survival tended to correlate with larger seeds in faba bean and lupin, and was associated with later flowering in lupin. A rosette-like winter growth habit (defined by lower height/number of leaves ratio of seedlings in January) was correlated with winter survival in all species (after partialling out the influence of seed size in faba bean and lupin). The optimal index of indirect selection for low winter mortality included the cold tolerance score, the seedling height/number of leaves ratio and the seed size for faba bean, the first two of these variables for pea, but only the first variable for lupin. The gain in predicted efficiency over direct selection was high for faba bean (29%) and modest for pea and lupin (⩽10%).
Competitive traits and the stability of wheat cultivars in differing natural weed environments on the northern Canadian Prairies
Authors: MASON H. , GOONEWARDENE L. , SPANER D.
Published: July 2007

Nine spring wheat cultivars, selected on the basis of height, tillering capacity and maturity, were grown in differing levels of natural weed presence at three locations in Edmonton and New Norway, Alberta between 2003 and 2004. The objectives of the study were to (1) identify competitive traits in wheat cultivars, (2) determine whether traits associated with competitive ability differ under increasing weed pressure and (3) assess cultivar stability in and adaptation to environments differing in yield potential and weed competition. Eight experimental environments (including conventionally and organically managed fields with and without common oats sown as a weed analogue) were grouped into low, medium and high weed pressure levels, based on mean total weed biomass. Tallness and early heading and maturity were related to increased grain yield at the highest weed level. Greater spikes/m2, tallness and early heading were associated with reduced weed biomass, depending on weed level. Principal component analysis (PCA) revealed that height accounted for a small amount of variation in low weed environments, yet was more important as weed pressure increased. Finlay–Wilkinson (Finlay & Wilkinson 1963) stability analysis demonstrated that cultivars responded differently in environments differing in yield potential and in weed pressure. Older wheat cultivars were generally more yield-stable across environments, while modern semidwarf cultivars were more sensitive to changes in weed level. The cultivar Park (released in 1963) was the most yield- and weed-stable cultivar, coupled with relatively high yields and average weed biomass accumulation, and may therefore be well adapted to low yielding or high weed environments.
Does laryngopharyngeal reflux affect healing and recovery after tonsillectomy?
Authors: Elwany S , Nour Y A , Magdy E A
Published: July 2007

Introduction:

Laryngopharyngeal reflux is increasingly being implicated in several otolaryngological disorders.

Aims:

To study a potential correlation between pre-operative laryngopharyngeal reflux and wound healing and recovery after tonsillectomy, based on subjective and objective findings.

Materials and methods:

A prospective, blinded study was undertaken, including 60 patients scheduled for tonsillectomy, divided into two equal groups: a study group (group A) with pre-operative laryngopharyngeal reflux documented using ambulatory 24-hour pH monitoring; and a control group (group B) without laryngopharyngeal reflux.

Results:

Group A had significantly higher pain scores on the seventh and 14th post-operative days (p = 0.022 andp = 0.000, respectively) and took a significantly longer time to return to normal eating (p = 0.013), compared with group B. Group A also showed significantly slower healing on the seventh and 14th post-operative days, as estimated by assessing the grade of post-operative slough formation (p = 0.016 andp = 0.029, respectively). A significant correlation between the number of pharyngeal reflux episodes and the degree of post-operative slough was also found.

Conclusions:

Laryngopharyngeal reflux can significantly decrease wound healing following tonsillectomy. Therefore, pre-operative recognition and management of this condition is desirable in order to eliminate its negative post-operative effect.
Connection formulae for spectral functions associated with singular Sturm–Liouville equations
Authors: Gilbert D. J. , Harris B. J.
Published: July 2007

We consider the Sturm–Liouville equation

with the initial condition

and suppose that Weyl's limit-point case holds at infinity. Let ρα(μ) be the corresponding spectral function and its symmetric derivative. We show that for almost all μ ∈ R, if exists and is positive for some α ∈ [0, π), then (i) exists and is positive for all β ∈ [0, π), and (ii) for all α1, α2 ∈ (0, π) \ {½ π},
Symplectic embeddings from R2n into some manifolds
Authors: Jiang M.-Y.
Published: July 2007

We show by elementary methods that there are symplectic embeddings from standard (R2n, ω0) into (Σ x R2n−2, ω ⊕ ω0) and (T2n−2k x R2k, ω ⊕ ω0), where (Σ, ω) is a closed two-dimensional symplectic manifold, and (T2n−2k, ω) is the torus with a constant symplectic form ω. Some estimates of Gromov's symplectic capacity are given for bounded domains in these manifolds.
Exact regions of oscillation for a neutral differential equation
Authors: Cheng S. S. , Lin Y. Z.
Published: July 2007

This paper is concerned with a neutral differential equation with four constant coefficients, one delay and one advancement. By means of the theory of envelopes, we consider all possible values of the parameters involved in the equation and obtain a complete set of necessary and sufficient conditions for all solutions to be oscillatory.
Spectral stability of modulated travelling waves bifurcating near essential instabilities
Authors: Sandstede B. , Scheel A.
Published: July 2007

Localized travelling waves to reaction-diffusion systems on the real line are investigated. The issue addressed in this work is the transition to instability which arises when the essential spectrum crosses the imaginary-axis. In the first part of this work, it has been shown that large modulated pulses bifurcate near the onset of instability; they are a superposition of the primary pulse with spatially periodic Turing patterns of small amplitude. The bifurcating modulated pulses can be parametrized by the wavelength of the Turing patterns. Furthermore, they are time periodic in a moving frame. In the second part, spectral stability of the bifurcating modulated pulses is addressed. It is shown that the modulated pulses are spectrally stable if and only if the small Turing patterns are spectrally stable, that is, if their continuous spectrum only touches the imaginary-axis at zero. This requires an investigation of the period map associated with the time-periodic modulated pulses.
Nonlinear Riemann—Hilbert problems with Lipschitz continuous boundary condition
Authors: Wegert E. , Efendiev M. A.
Published: July 2007

Using a norm inequality for singular integral operators in pairs of weighted Lebesgue spaces we are able to prove existence and uniqueness results for solutions of nonlinear RiemannHilbert problems with non-compact Lipschitz continuous restriction curves.
Complete blow-up for quasilinear degenerate parabolic equations
Authors: Suzuki R.
Published: July 2007

Non-negative post-blow-up solutions of the quasilinear degenerate parabolic equation

in RN (or a bounded domain with Dirichlet boundary condition) are studied. Various sufficient conditions for complete blow-up of solutions are given.
Estimates for the periodic and semi-periodic eigenvalues of Hill's equation
Authors: Coskun Haskiz , Harris B. J.
Published: July 2007

We consider Hill's equation

on the interval [0, a] with periodic and semi-periodic boundary condition. We derive the asymptotic form of the eigenvalues without smoothness conditions on q.
Uniqueness and stability for the determination of boundary defects by electrostatic measurements
Authors: Rondi L.
Published: July 2007

The inverse problem of the determination of boundary defects in a planar conductor by a finite number of electrostatic measurements on the boundary is considered. Uniqueness results and stability estimates are proved under essentially minimal regularity assumptions on the data. Finally, Lipschitz estimates for the determination of surface linear cracks are developed.
Inequalities for the Hurwitz zeta function
Authors: Alzer Horst
Published: July 2007

Let be the Hurwitz zeta function. Furthermore, let p > 1 and α ≠ 0 be real numbers and n ≥ 2 be an integer. We determine the best possible constants a(p, α, n), A(p, α, n), b(p, n) and B(p, n) such that the inequalities

and

hold for all positive real numbers x1,…,xn.
A construction of laminates from rank-1 polygons
Authors: Iqbal Z.
Published: July 2007

We construct non-trivial laminates distributed continuously along a smooth closed ‘evolute’ curve by approximating an auxiliary (‘involute’) curve by a polygon with rank-1 sides. We give an explicit example in which the evolute has no rank-1 connections. Using these techniques, given a finite set of matrices B1,…,Br and any other matrix A, we show how to construct a laminate with positive mass at each Bi, any proportion less than 1 of its support on the Bi, and centre of mass at A.
The LSW model for Ostwald ripening with kinetic undercooling
Authors: Niethammer Barbara
Published: July 2007

We study a Stefan problem for coarsening of many small particles of solid phase in undercooled liquid phase which includes surface tension and kinetic undercooling effects. A mean-field model is derived by homogenization of the free boundary problem. It extends the classical theory of Lifshitz et al. by taking into account effects due to kinetic undercooling.
Relaxation of some multi-well problems
Authors: Bhattacharya Kaushik , Dolzmann Georg
Published: July 2007

Mathematical models of phase transitions in solids lead to the variational problem, minimize ∫Ω W (Du) dx, where W has a multi-well structure, i.e. W = 0 on a multi-well set K and W > 0 otherwise. We study this problem in two dimensions in the case of equal determinant, i.e. for K = SO(2)U1 ∪ … ∪SO(2)Uk or K = O(2)U1 ∪ … ∪ O(2)Uk for U1, … , Uk ∈ M2×2 with det Ui = δ in three dimensions when the matrices Ui are essentially two-dimensional and also for K = SO(3)Û1 ∪ … ∪ SO(3)Ûk for U1, … , Uk ∈ M3×3 with , which arises in the study of thin films. Here, Ûi denotes the (3×2) matrix formed with the first two columns of Ui. We characterize generalized convex hulls, including the quasiconvex hull, of these sets, prove existence of minimizers and identify conditions for the uniqueness of the minimizing Young measure. Finally, we use the characterization of the quasiconvex hull to propose ‘approximate relaxed energies’, quasiconvex functions which vanish on the quasiconvex hull of K and grow quadratically away from it.
Qualitative behaviour of positive solutions of a predator—prey model: effects of saturation
Authors: Du Yihong , Lou Yuan
Published: July 2007

We study a predator–prey system with Holling–Tanner interaction terms. We show that if the saturation rate m is large, spatially inhomogeneous steady-state solutions arise, contrasting sharply with the small-m case, where no such solution could exist. Furthermore, for large m, we give sharp estimates on the ranges of other parameters where spatially inhomogeneous solutions can exist. We also determine the asymptotic behaviour of the spatially inhomogeneous solutions as m → ∞, and an interesting relation between this population model and free boundary problems is revealed.
Analyticity of solitary wave solutions to generalized Kadomtsev—Petviashvili equations
Authors: Kato Keiichi , Pipolo Patrick-Nicolas
Published: July 2007

In this paper we prove the existence and analyticity of solitary waves of generalized Kadomtsev–Petviashvili equations satisfying a set of conditions on linear and nonlinear terms which determine their behaviour at infinity and around 0.
Global solution to the equations of viscous gas flows
Authors: Wang Dehua
Published: July 2007

The global solution, stability and evolution of regularities are studied for the initial-boundary-value problem of a viscous compressible gas flow. With global a priori estimates and careful analysis, the existence of global classical solutions in Hölder space is established.
Norovirus–host interaction: implications for disease control and prevention
Authors: Tan Ming , Jiang Xi
Published: July 2007

Noroviruses (NVs) are a major cause of acute gastroenteritis epidemics in both developing and developed countries and affect people of all ages. Three main human histo-blood group antigens (HBGAs) – the ABO, Lewis and secretor families – are involved in NV recognition and eight strain-specific receptor-binding patterns in two major binding groups have been described. The receptor-binding interface is located at the outermost surface of the P domain of the viral capsid. Each interface contains two major binding sites and each site interacts with a carbohydrate side-chain of the HBGAs via multiple hydrogen bonds. Soluble HBGAs in human milk are able to block binding of NV to HBGA receptors, suggesting a potential decoy receptor for the protection of infants from NV infection. Phylogenetic analysis has revealed limited genetic relatedness among NVs with similar receptor-binding patterns. This review summarises and discusses recent advances and highlights implications for future studies in the control and prevention of NV gastroenteritis.
On the spatiotemporal behavior of sea ice concentration anomalies in the Northern Hemisphere
Authors: Lukovich J. V. , Barber D. G.
Published: July 2007

Reduction in the aerial extent and thickness of sea ice in the Northern Hemisphere is an important element in understanding how the arctic responds to global‐scale climate variability and change. Previous studies have demonstrated a significant reduction in minimum sea ice extent [Serreze et al., 2003] with record reduction in 2005. Observational studies attribute this phenomenon to variations in sea level pressure and large‐scale atmospheric teleconnection patterns such as the Northern Annular Mode (NAM) [Deser et al., 2000; Serreze et al., 2003]. In this study we examine variations in sea ice in the context of spatiotemporal variability of sea ice concentration (SIC) anomalies in the Northern Hemisphere during the onset of ice formation. Examined in particular are timescales associated with coherent regions of persistence in an e‐folding time spatial distribution (EFSD). Annual variations of weekly SIC anomalies are studied and spatial relations between positive and negative SIC anomalies are explored on a hemispheric scale. The results from this investigation demonstrate coherent SIC persistence patterns throughout the Northern Hemisphere, with timescales ranging from 3 to 7 weeks. Spatial correspondence between negative trends in SIC anomalies and the EFSD suggests that the same mechanism may be responsible for both increased ice reduction and persistence in this region. Examination of spatial coherence in SIC anomalies indicates that maximum SIC anomalies prevail near the Kara Sea, Beaufort Sea, and Chukchi Sea regions during late summer/early fall from 1979 to 2004. A latitudinal assessment at 80°, 70°, and 60°N indicates a poleward shift and retreat in SIC anomalies, while also underlining the decadal shift in variability often attributed to the NAM.
Simulation of field injection experiments in heterogeneous unsaturated media using cokriging and artificial neural network
Authors: Ye Ming , Khaleel Raziuddin , Schaap Marcel G. , Zhu Jianting
Published: July 2007

Simulations of moisture flow in heterogeneous soils are often hampered by lack of measurements of soil hydraulic parameters, making it necessary to rely on other sources of information. In this paper, we develop a methodology to integrate data that can be easily obtained (for example, initial moisture content, θi, bulk density, and soil texture) with data on soil hydraulic properties via cokriging and Artificial Neural Network (ANN)‐based pedotransfer functions. The method is applied to generate heterogeneous soil hydraulic parameters at a field injection site in southeastern Washington State. Stratigraphy at the site consists of imperfectly stratified layers with irregular layer boundaries. Cokriging is first used to generate three‐dimensional heterogeneous fields of bulk density and soil texture using an extensive data set of field‐measured θi, which carry signature about site heterogeneity and stratigraphy. Soil texture and bulk density are subsequently input into an ANN‐based site‐specific pedotransfer function to generate three‐dimensional heterogeneous soil hydraulic parameter fields. The stratigraphy at the site is well represented by the estimated pedotransfer variables and soil hydraulic parameters. The parameter estimates are then used to simulate a field injection experiment at the site. A relatively good agreement is obtained between the simulated and observed moisture contents. The spatial distribution pattern of observed moisture content as well as the southeastward moisture movement is captured well in the simulations. In contrast to earlier work using an effective parameter approach (Yeh et al., 2005), we are able to reproduce the observed splitting of the moisture plume in a coarse sand unit that is sandwiched between two fine‐textured units. The simple method of combining cokriging and ANN for site characterization provides unbiased prediction of the observed moisture plume and is flexible so that additional measurements of various types can be included as they become available.
Anti‐cyclonic eddies northwest of Luzon in summer–fall observed by satellite altimeters
Authors: Yuan Dongliang , Han Weiqing , Hu Dunxin
Published: July 2007

Anti‐cyclonic eddies northwest of Luzon of the Philippines in summer‐fall are identified in the merged data products of satellite altimeters of Topex/Poseidon, Jason‐1 and European Research Satellites. The generation and propagation of the anti‐cyclonic eddies, which are confirmed by satellite ocean color data, are found to be a seasonal phenomenon that is phase‐locked to the onset of the southwesterly monsoon and the relaxation of the cyclonic wind curl in the northeastern South China Sea. The eddies originate from northwest of Luzon in summer, move across the northeastern South China Sea to reach the China continental slope in fall, and propagate southwestward along the continental slope in fall–winter, inducing shelfbreak current variations in the western South China Sea in fall–winter. The anti‐cyclonic eddy discovered by Li et al. (1998) in the northern South China Sea is found to originate from northwest of Luzon and carry primarily the South China Sea waters. It does not appear to be an eddy shed from the Kuroshio in the Luzon Strait area as alluded by Li et al. (1998) and others.
Development of the Literacy Achievement Gap: A Longitudinal Study of Kindergarten Through Third Grade
Authors: Foster Wayne A. , Miller Merideth
Published: July 2007

Purpose

The major goal of this study was to specify the developmental trajectories for phonics and early text comprehension skills of children from kindergarten through third grade.

Method

Data from the Early Childhood Longitudinal Study (N= 12,261) were used in this study. The participants were divided into 3 school readiness groups based on an assessment of literacy skill development at the time of entrance into kindergarten. The different groups were tracked on phonics and text comprehension development through the third grade.

Results

Students in the average and high literacy readiness groups achieved high scores in decoding (phonics) by the end of the first grade. Students in the low readiness group did not match these scores until the third grade. Although the phonics gap was essentially closed in the third grade, a second, very significant text comprehension gap was exposed. The 3 readiness groups were analyzed to assess the relative contributions of parent education, income, and kindergarten literacy score to third-grade literacy achievement.

Clinical Implications

The results of this study stress the need for speech-language pathologists to assess emergent literacy skills in their speech and language clients and to include appropriate literacy goals in the treatment regimen as a means for reducing the potential need for identification as learning disabled in reading in the later years of elementary school.
Narrative and Vocabulary Development of Bilingual Children From Kindergarten to First Grade: Developmental Changes and Associations Among English and Spanish Skills
Authors: Uccelli Paola , Páez Mariela M.
Published: July 2007

Purpose

Research has identified English oral language proficiency as being critical for bilingual students' literacy development. This study examines developmental patterns and associations among oral vocabulary and narrative skills in a longitudinal sample of 24 Spanish/English bilingual children from low socioeconomic backgrounds so as to further our understanding of the development of oral proficiency.

Method

English and Spanish data were gathered using standardized vocabulary tests and narrative elicitation tasks provided to kindergartners and first graders. Narratives were coded for length using two measures of productivity and for quality at two levels: story score and language score. Descriptive, correlation, multivariate, and regression analyses were conducted.

Results

Significant gains from kindergarten to first grade were found for all English oral language measures. Despite showing improvements in English vocabulary, the majority of children continued to score below the monolingual mean in first grade. For English narrative productivity, total number of different words (TDW) proved to be a sensitive developmental measure in contrast to total number of words (TNW). In Spanish, significant gains were noted only for narrative story score. Kindergarten Spanish story scores predicted first-grade English narrative quality even when controlling for the effects of English vocabulary and English narrative productivity. First-grade Spanish narrative quality was best predicted by Spanish vocabulary.

Implications

The need for early assessment and monitoring of expressive vocabulary and oral narrative skills, and the potential contributions of Spanish story organization skills to English narrative performance in bilingual children from low socioeconomic families, are highlighted.
Teaching Struggling Readers Who Are Native Spanish Speakers: What Do We Know?
Authors: Mathes Patricia G. , Pollard-Durodola Sharolyn D. , Cárdenas-Hagan Elsa , Linan-Thompson Sylvia , Vaughn Sharon
Published: July 2007

Purpose

The purpose of this article is to share what we have learned from a series of 4 scientific studies about preventing reading failure through early intervention with native Spanish-speaking students who are struggling readers. The goal is to provide guidance to practitioners about effective practices for working with native Spanish-speaking children who are struggling to become readers using evidence rather than conjecture and opinion.

Method

First, the method and findings are summarized from each of 4 scientific studies (2 English, 2 Spanish) examining supplemental reading intervention that was provided in addition to core reading instruction in first grade. Second, the supplemental interventions are detailed. Next, aspects of instruction that appear to generalize from what we know about preventing reading failure among native English speakers are discussed. Last, the types of adjustments made to this instruction in order to accommodate the needs of English language learners are examined.

Implications

Outcomes confirm that native Spanish-speaking children benefited from explicit, systematic instruction that shared many of the same elements that have been proven to be effective with native English speakers. Further, English as a second language teaching techniques (i.e., use of concrete gestures and visual aids, consistent and repeated routines, and use of repeated phrases and consistent language) benefited native Spanish speakers who were struggling to learn to read in English. However, little transfer of knowledge from one language to another was detected.
Explicit star products on orbits of nilpotent Lie groups with square integrable representations
Authors: Maillard Jean-Marie
Published: July 2007

We construct star products on the orbits of nilpotent Lie groups with square integrable representations. These star products, which are generalizations of the Moyal star product, are obtained by formal expansion from integral formulas in the Schwartz space of functions on the orbits. These integral formulas are deduced by Fourier transformation from associative but not commutative twisted convolution products on these groups modulo their centers, which are associated with generalized Weyl transformations. We express explicitly the two cochains of these star products as function of the terms of the Campbell-Hausdorff formula, and we study the associativity of these formal star products. Then, we develop a symbolic calculus on the space of polynomials on the orbits, and we show, in particular, that these star products correspond to the completely symmetric ordering.
A theoretical interpretation of magnetoresistance mobility in silicon inversion layers
Authors: Donetti L. , Gámiz F. , Cristoloveanu S.
Published: July 2007

The magnetoresistance technique has been introduced recently as a means of determining experimentally the mobility in bulk metal-oxide-semiconductor transistor and silicon-on-insulator devices. This technique does not require a precise determination of the channel length, and it also has the advantage of allowing mobility extraction when the application of other methods is problematic, notably with weak inversion and short device length. The magnetoresistance mobility extracted in this way is related but not identical to the normal effective drift mobility. In this work we simulate electron transport in the presence of a magnetic field for different device structures. The simulations allow us to study the conditions under which magnetoresistance mobility and effective mobility coincide, and to measure the difference, where it exists. We find that at low temperatures the two quantities coincide, while at room temperature a difference of more than 20% may appear. We take this to be a consequence of the energy difference between subbands and the resulting distribution of electrons among them. We then explain the fact that the two mobility measures coincide at low temperatures when only the ground subband is occupied by analyzing the energy dependence of the momentum relaxation time.
In situ reflection high energy electron diffraction surface pole figure study of biaxial texture evolution in anisotropic Mg nanoblades during shadowing growth
Authors: Tang F. , Wang G.-C. , Lu T.-M.
Published: July 2007

The reflection high energy electron diffraction (RHEED) surface pole figure technique has been applied to an in situ study of the biaxial texture evolution in the anisotropic film of Mg nanoblades. These nanoblades were grown by thermal vapor under the shadowing effect using oblique angle deposition. To compensate for the effects of the anisotropic morphology of the Mg film on the RHEED surface pole figure, a method of intensity normalization has been employed. From the normalized pole figures, we observed a development of (101¯0)[0001] biaxial texture in the film during the growth. When the film grows thicker the texture axes tilt more towards the incident vapor flux. The variation of the azimuthal angle orientation is mainly around the [0001] axis during growth and the azimuthal dispersion angle around the [0001] axis reduces. The change of texture axis tilting angle has been correlated to the change of the nanoblade tilting angle. The azimuthal angle alignment of the nanoblades is argued to be the result of maximizing the vapor flux capture cross section by nanoblades during the growth.
Origin of recoil hysteresis loops in Sm–Co∕Fe exchange-spring magnets
Authors: Choi Y. , Jiang J. S. , Pearson J. E. , Bader S. D. , Liu J. P.
Published: July 2007

Open recoil loops are often interpreted as a consequence of a breakdown in exchange coupling and attributed to the decoupled soft phase in exchange-coupled permanent magnets. However, in element-specific recoil loop measurements on Sm–Co∕Fe exchange spring magnets, the authors found that the open recoil loops were present not only in the soft (Fe) layer but also in the hard (Sm–Co) layer, and were not a consequence of exchange coupling breakdown between the soft and hard layers. Comparison between the experimental results and micromagnetic calculations reveals that the observed open recoil loops originate from the anisotropy variations in the Sm–Co layer.
Microstructure of neat alcohols: A molecular dynamics study
Authors: Zoranić Larisa , Sokolić Franjo , Perera Aurélien
Published: July 2007

Neat methanol and tert-butanol are studied by molecular dynamics with the focus on the microstructure of these two alcohols. The site-site radial distribution functions, the corresponding structure factors, and an effective local one-body density function are shown to be the appropriate statistical quantities that point in a complementary manner towards the same microstructure for any given liquid. Methanol is found to be a weakly associated liquid forming various chainlike patterns (open and closed) while tert-butanol is almost entirely associated and forms micellelike primary pattern. The presence of stable local microheterogeneity within homogeneous disordered phase appears as a striking feature of these liquids. The absence of any such apparent clustering in water—a stronger hydrogen bonding liquid—through the same two statistical quantities is analyzed.
High-efficiency GaInP∕GaAs∕InGaAs triple-junction solar cells grown inverted with a metamorphic bottom junction
Authors: Geisz J. F. , Kurtz Sarah , Wanlass M. W. , Ward J. S. , Duda A. , Friedman D. J. , Olson J. M. , McMahon W. E. , Moriarty T. E. , Kiehl J. T.
Published: July 2007

The authors demonstrate a thin, Ge-free III–V semiconductor triple-junction solar cell device structure that achieved 33.8%, 30.6%, and 38.9% efficiencies under the standard 1sun global spectrum, space spectrum, and concentrated direct spectrum at 81suns, respectively. The device consists of 1.8eV Ga0.5In0.5P, 1.4eV GaAs, and 1.0eV In0.3Ga0.7As p-n junctions grown monolithically in an inverted configuration on GaAs substrates by organometallic vapor phase epitaxy. The lattice-mismatched In0.3Ga0.7As junction was grown last on a graded GaxIn1−xP buffer. The substrate was removed after the structure was mounted to a structural “handle.” The current-matched, series-connected junctions produced a total open-circuit voltage over 2.95V at 1sun.
Electrophotoluminescence of ZnO film
Authors: Ma Xiangyang , Chen Peiliang , Li Dongsheng , Zhang Yuanyuan , Yang Deren
Published: July 2007

The electric-field-controlled photoluminescence (PL), i.e., electrophotoluminescence (EPL) of ZnO film has been investigated via a ZnO-based metal-insulator-semiconductor (MIS) structure on a silicon substrate applied with different biases. Compared with the PL of ZnO film in the case where there is no bias on the MIS structure, the positive bias with negative voltage applied on silicon substrate significantly enhances the near-band-edge ultraviolet emission while suppressing the deep-level-related visible emissions, whereas the negative bias hardly changes the PL of ZnO film. The mechanism for EPL of ZnO film is proposed in terms of the electric-field effect on the bending of energy bands of ZnO.
Miniaturized dynamic light scattering instrumentation for use in microfluidic applications
Authors: Chastek Thomas Q. , Beers Kathryn L. , Amis Eric J.
Published: July 2007

Five designs for a miniaturized dynamic light scattering (DLS) instrument are described that incorporate microfluidic flow of the sample volume and fiber optic probes directly embedded into the sample. These instruments were demonstrated to accurately determine the size of 10–100nm particles dispersed in organic and aqueous solvents with most sample sizes less than 150μl. Small stir bars were incorporated directly into the instruments, and enabled blending of different solutions immediately prior to DLS measurements. Demonstration of the instruments’ capabilities include high throughput measurements of the micelle to unimer transition for poly(styrene-b-isoprene) in mixed toluene/hexadecane solvent, obtained by systematically blending toluene-rich and hexadecane-rich polymer solutions. The critical solvent composition was quickly identified with less than 20mg of polymer. Further capabilities include temperature control, demonstrated by identification of a critical micelle temperature of poly(ethylene oxide-b-propylene oxide-b-ethylene oxide), as well as multiangle DLS measurements.
Pneumatically actuated elastomeric device for nanoscale surface patterning
Authors: Li Shifeng , Dellinger Timothy M. , Wang Qin , Szegedi Sandra , Liu Chang
Published: July 2007

The authors present a simple polydimethysiloxane (PDMS) device for nanoscale surface patterning by controllably bringing a hard silicon nitride tip on a PDMS membrane in and out of contact with surfaces using pressurized gas to inflate the membrane. The writing process is analogous to contact printing. By regulating the pressured gas to actuate the silicon nitride tip on the PDMS membrane, the nanometer size features can be easily fabricated on substrates. Moreover, using the dot matrix method, this PDMS device can masklessly fabricate arbitrary patterns. In this letter, a nanometer scale three-line pattern is demonstrated.
Large hysteretic magnetoresistance in high-mobility semiconductor quantum wires bridged by single-domain nanomagnets
Authors: Bae J.-U. , Lin T.-Y. , Yoon Y. , Kim S. J. , Bird J. P. , Imre A. , Porod W. , Reno J. L.
Published: July 2007

The authors discuss hysteresis in the magnetoresistance of hybrid semiconductor/ferromagnetic devices composed of high-mobility semiconductor quantum wires (QWs) bridged by single-domain Co nanomagnets (NMs). This hysteresis is shown to be consistent with the ballistic transport of electrons in the QW through the nonuniform magnetic field generated by the NM. It is also found to be strongly dependent on tilt angle, suggestive of a transition between easy- and hard-axis magnetizations.
Early stage of material movements in eutectic SnPb solder joint undergoing current stressing at 150°C
Authors: Ho C. E. , Lee A. , Subramanian K. N. , Liu W.
Published: July 2007

X-ray fluorescence spectroscopy was used to study movements of Sn and Pb in the eutectic SnPb solder joint undergoing electromigration with a current density of 104A∕cm2 at 150°C. During early stages of current stressing, Sn moves toward the anode faster than Pb. However, on continued application of current stressing, both Sn and Pb will continue to accumulate at the anode. Such accumulation of conductive species facilitates the formation of hillock with associated valley near the cathode.