bluuebunny/crossref_metadata_2025 huggingface dataset:
Stellungnahme zur Eingliederungshilfe nach § 35a SGB VIII der Kommission Jugendhilfe der kinder- und jugendpsychiatrischen Fachgesellschaften *unter Mitarbeit von Thomas Meysen
Authors: M. Fegert Jörg , Roosen-Runge Gotthard , Thoms Edelhard , Kirsch Ursula , Kölch Michael
Published: July 2008

Zusammenfassung: Die Eingliederungshilfe für psychisch kranke Kinder und Jugendliche (§ 35a SGB VIII) birgt für praktisch tätige Kinder- und Jugendpsychiater Probleme. Welche Aufgaben hat der Kinder- und Jugendpsychiater im Verfahren, welche Rechte, welche gesetzlichen Bestimmungen sind zu beachten, wie ist die Kooperation mit dem Jugendamt und den Eltern zu gestalten, welche Liquidation ist möglich. Die gemeinsame Kommission Jugendhilfe der Fachgesellschaften hat dazu eine Stellungnahme erarbeitet, die die aktuelle Fassung der Eingliederungshilfe darstellt und häufige Probleme und Lösungsmöglichkeiten aufzeigt. Zusätzlich wurde eine Musterstellungnahme für die Eingliederungshilfe erarbeitet.
The 2005 and 2006 DANDELIONS NO2 and aerosol intercomparison campaigns
Authors: Brinksma E. J. , Pinardi G. , Volten H. , Braak R. , Richter A. , Schönhardt A. , van Roozendael M. , Fayt C. , Hermans C. , Dirksen R. J. , Vlemmix T. , Berkhout A. J. C. , Swart D. P. J. , Oetjen H. , Wittrock F. , Wagner T. , Ibrahim O. W. , de Leeuw G. , Moerman M. , Curier R. L. , Celarier E. A. , Cede A. , Knap W. H. , Veefkind J. P. , Eskes H. J. , Allaart M. , Rothe R. , Piters A. J. M. , Levelt P. F.
Published: July 2008

Dutch Aerosol and Nitrogen Dioxide Experiments for Validation of OMI and SCIAMACHY (DANDELIONS) is a project that encompasses validation of spaceborne measurements of NO2 by the Ozone Monitoring Instrument (OMI) and Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), and of aerosol by OMI and Advanced Along‐Track Scanning Radiometer (AATSR), using an extensive set of ground‐based and balloon measurements over the polluted area of the Netherlands. We present an extensive data set of ground‐based, balloon, and satellite data on NO2, aerosols, and ozone obtained from two campaigns within the project, held during May–June 2005 and September 2006. We have used these data for first validation of OMI NO2, and the data are available through the Aura Validation Data Center website for use in other validation efforts. In this paper we describe the available data, and the methods and instruments used, including the National Institute of Public Health and the Environment (RIVM) NO2 lidar. We show that NO2 from Multi‐Axis Differential Optical Absorption Spectroscopy (MAX‐DOAS) compares well with in situ measurements. We show that different MAX‐DOAS instruments, operating simultaneously during the campaign, give very similar results. We also provide unique information on the spatial homogeneity and the vertical and temporal variability of NO2, showing that during a number of days, the NO2 columns derived from measurements in different directions varied significantly, which implies that, under polluted conditions, measurements in one single azimuth direction are not always representative for the averaged field that the satellite observes. In addition, we show that there is good agreement between tropospheric NO2 from OMI and MAX‐DOAS, and also between total NO2 from OMI and direct‐sun observations. Observations of the aerosol optical thickness (AOT) show that values derived with three ground‐based instruments correspond well with each other, and with aerosol optical thicknesses observed by OMI.
Resolution of direction of oceanic magnetic lineations by the sixth‐generation lithospheric magnetic field model from CHAMP satellite magnetic measurements
Authors: Maus S. , Yin F. , Lühr H. , Manoj C. , Rother M. , Rauberg J. , Michaelis I. , Stolle C. , Müller R. D.
Published: July 2008

The CHAMP satellite continues to provide highly accurate magnetic field measurements from decreasing orbital altitudes (<350 km) at solar minimum conditions. Using the latest 4 years (2004–2007) of readings from the CHAMP fluxgate magnetometer, including an improved scalar data product, we have estimated the lithospheric magnetic field to spherical harmonic degree 120, corresponding to 333 km wavelength resolution. The data were found to be sensitive to crustal field variations up to degree 150 (down to 266 km wavelength), but a clean separation of the lithospheric signal from ionospheric and magnetospheric noise sources was achieved only to degree 120. This new MF6 model is the first satellite‐based magnetic model to resolve the direction of oceanic magnetic lineations, revealing the age structure of oceanic crust.
Quorum-sensing signals in the microbial community of the cabbage white butterfly larval midgut
Authors: Borlee Bradley R , Geske Grant D , Robinson Courtney J , Blackwell Helen E , Handelsman Jo
Published: July 2008

The overall goal of this study was to examine the role of quorum-sensing (QS) signals in a multispecies microbial community. Toward this aim, we studied QS signals produced by an indigenous member and an invading pathogen of the microbial community of the cabbage white butterfly (CWB) larval midgut (Pieris rapae). As an initial step, we characterized the QS system in Pantoea CWB304, which was isolated from the larval midgut. A luxI homolog, designated panI, is necessary for the production of N-acyl-l-homoserine lactones (AHLs) by Pantoea CWB304. To determine whether AHL signals are exchanged in the alkaline environment of the midgut, we constructed AHL-sensing bioluminescent reporter strains in Pantoea CWB304 and a panI mutant of this strain. In the gut of the CWB larvae, the reporter in an AHL-deficient Pantoea CWB304 detected AHLs when coinoculated with the wild type. To study the role of AHL signals produced by a community invader, we examined pathogenesis of Pseudomonas aeruginosa PAO1 in CWB larvae. Mortality induced by P. aeruginosa PAO1 was significantly reduced when signaling was interrupted by either a potent chemical inhibitor of QS or mutations in the lasI and rhlI AHL synthases of P. aeruginosa PAO1. These results show that AHLs are exchanged among bacteria in the alkaline gut of CWB larvae and contribute to disease caused by P. aeruginosa PAO1.
Stalls and Revisions: A Developmental Perspective on Sentence Production
Authors: Rispoli Matthew , Hadley Pamela , Holt Janet
Published: July 2008

Purpose

The purpose of this research was to test the empirical validity of the stall–revision distinction and to provide a characterization of the development of sentence production using this distinction.

Method

The stall–revision dichotomy for sentence disruptions was studied in 20 typically developing children. The children’s production of short sentences was observed from 21 to 33 months of age. Developmental changes in stall and revision rates were analyzed using hierarchical linear modeling, time centered at 27 months. Differences between stall and revision rates across 2 levels of sentence length were also explored with repeated-measures analysis of variance when the children were 33 months of age.

Results

A clear development trend was observed for revision rate. At 27 months of age, revisions occurred in approximately 1% of children’s sentences and increased with age. No significant individual differences were apparent in the growth parameters for revision rate. In contrast, group developmental trends in stall rate were not discernable. However, stall rate increased significantly with sentence length, whereas revision rate remained constant.

Conclusion

The contrasting pattern of findings provides support for the stall–revision dichotomy. The authors argue that the developmental changes in revision rate reflect changes in the children’s ability to monitor their language production.
Vocabulary Abilities of Children With Williams Syndrome: Strengths, Weaknesses, and Relation to Visuospatial Construction Ability
Authors: Mervis Carolyn B. , John Angela E.
Published: July 2008

Purpose

This project was designed to identify relative strengths and weaknesses in vocabulary ability for children with Williams syndrome (WS) and to demonstrate the importance of stringent matching criteria for cross-group comparisons.

Method

Children with WS and typically developing (TD) children completed standardized assessments of intellectual and language ability. Children with WS also completed a visuospatial construction ability assessment.

Results

Study 1: Concrete and relational vocabulary standard scores were significantly lower for 5- to 7-year-olds with WS than for TD children. Children with WS earned significantly higher standard scores for concrete than for relational vocabulary. When groups were stringently matched for relational vocabulary size, children with WS did not evidence a specific weakness in spatial vocabulary. Study 2: Standard scores for relational vocabulary were similar to those for visuospatial construction ability for 5- to 7-year-olds with WS. Study 3: Nine- to 11-year-olds with WS demonstrated very limited relational vocabulary ability; relational vocabulary ability at 5–7 years was highly correlated with later relational language ability.

Conclusions

Concrete vocabulary is a relative strength for children with WS; relational vocabulary ability is very limited and is at about the level of visuospatial construction ability. Accurate determination of group comparison results depends on stringent group matching.
Experimental Evaluation of a Preschool Language Curriculum: Influence on Children’s Expressive Language Skills
Authors: Justice Laura M. , Mashburn Andrew , Pence Khara L. , Wiggins Alice
Published: July 2008

Purpose

The primary purpose of this study was to investigate child impacts following implementation of a comprehensive language curriculum, the Language-Focused Curriculum (LFC; Bunce, 1995), within their preschool classrooms. As part of this larger purpose, this study identified child-level predictors of expressive language outcomes for children attending at-risk preschool programs as well as main effects for children’s exposure to the language curriculum and its active ingredients—namely, teacher use of language stimulation techniques (LSTs; e.g., open questions, recasts, models).

Method

Fourteen preschool teachers were randomly assigned to 2 conditions. Treatment teachers implemented the experimental curriculum for an academic year; a total of 100 children were enrolled in their classrooms. Comparison teachers maintained their prevailing curriculum; a total of 96 children were enrolled in these classrooms. Teachers’ fidelity of implementation was monitored using structured observations conducted 3 times during the academic year. Children’s growth in expressive language was assessed using measures derived from language samples in the fall and spring, specifically percent complex utterances, rate of noun use, number of different words, and upper bound index.

Results

Children’s language skill in the fall, socioeconomic status (household income), and daily attendance served as significant, positive predictors of their language skill in the spring. The impact of the language curriculum and LST exposure was moderated by children’s classroom attendance, in that the language curriculum accelerated language growth for children who attended preschool regularly; a similar effect was seen for LST exposure.

Conclusions

Adoption of a comprehensive language curriculum may provide a value-added benefit only under highly specific circumstances. Findings suggest that at-risk children who receive relatively large doses of a curriculum (as measured in days of attendance during the academic year) that emphasizes quality language instruction may experience accelerated expressive language growth during pre-kindergarten.
The Effect of the 226-Hz Probe Level on Contralateral Acoustic Stapedius Reflex Thresholds
Authors: Day Jessica E. , Feeney M. Patrick
Published: July 2008

Purpose

The purpose of this study was to examine the effect of the 226-Hz probe level on the acoustic stapedius reflex threshold.

Method

Contralateral reflex thresholds for a 1000-Hz pure-tone stimulus were obtained from 40 young adults with normal hearing using an experimental system at four 226-Hz probe levels (70, 75, 80, and 85 dB SPL) with a repeated measures experimental design.

Results

A repeated measures analysis of variance revealed that as the probe level increased over this 15-dB range, there was a mean decrease in reflex threshold of 2.5 dB SPL (
p
< .001), with the largest decrease for an individual participant of 12 dB.

Conclusion

The results suggest that the level of the 226-Hz probe tone as used in clinical reflex measurements and as specified in the American National Standards Institute (1987) standard is sufficiently high to affect the acoustic reflex by facilitating its activation. The effect is small, on average, but may be of clinical significance for some individuals.
Modulating effects of the low-frequency source on ion energy distributions in a dual frequency capacitively coupled plasma
Authors: Li Xiao-Song , Bi Zhen-Hua , Chang Da-Lei , Li Zhi-Cheng , Wang Shuai , Xu Xiang , Xu Yong , Lu Wen-Qi , Zhu Ai-Min , Wang You-Nian
Published: July 2008

With the energy resolved quadrupole mass spectrometer and hybrid simulation, the influence of low-frequency (LF) source parameters on the ion energy distributions (IEDs) of argon ions impinging on the grounded electrode was studied, both experimentally and numerically, in a dual frequency capacitively coupled plasma. It was shown that for decreasing LF or increasing LF power, the high energy peak in IEDs shifts toward the high energy region significantly. The simulation results were in general agreement with the experimental data.
Na
−
photolysis in THF: Charge transfer to solvent studied from the donors perspective in <10fs detail
Authors: Shoshanim Ofir , Ruhman Sanford
Published: July 2008

Two and three pulse photolysis experiments on terahydrofuran (THF) solutions of Na−, utilizing hyperspectral probing, are described. The objective is to probe the extent and duration of energetic correlations between the primary charge transfer to solvent (CTTS) fragments which are an e− and Na0. The latter is characterized by an intense visible absorption spectrum with fine structure reflecting the atom’s immediate solvent environment. Pump-probe experiments with ∼6fs pulses show that for the majority of irradiated ions, the electron ejection and production of unperturbed Na0 is effectively over in ∼15fs, with no precursors. Three pulse experiments further demonstrate this to be true for nearly all ions irradiated at 3eV. Thus, the 400nm data provide a detailed spectral record of the formation and subsequent solvation and polarization of neutral sodium bubbles in THF. Measures are presented for parametrizing the ensuing spectral evolution. In contrast, exciting at 1.5eV, the red edge of the CTTS band leads to charge transfer with less than unity quantum efficiency. The complementary fraction of absorbing ions is photostable at 800nm, presumably due to preferential solvent stabilization. Prompt secondary irradiation at 2μm can complete ionization of that population leading to additional generation of Na0 but exhibiting much more pronounced spectral structure. Thus, at low photon energies, a short lived correlated and bound electronic excited state is produced with significant yield. These results are discussed in terms of classical models for CTTS spectra, as well as more recent simulations and experiments concerning CTTS in this and other related systems.
Intermediate Hamiltonian Fock-space multireference coupled-cluster method with full triples for calculation of excitation energies
Authors: Musial Monika , Bartlett Rodney J.
Published: July 2008

The intermediate Hamiltonian multireference coupled-cluster (CC) method with singles, doubles, and triples within the excited (1,1) sector of Fock space (FS) is implemented and formulated to calculate excitation energies (EEs). Due to the intermediate Hamiltonian formulation, which provides a robust computational scheme for solving the FS-CC equations, coupled to an efficient factorization strategy, relatively large basis sets and model spaces are employed permitting basis set converged comparisons of the calculated vertical EEs, which can be compared to the experimental data for the N2 and CO molecules. The issue of charge-transfer separability is also addressed.
A new integrable generalization of the Korteweg–de Vries equation
Authors: Karasu-Kalkanlı Ayşe , Karasu Atalay , Sakovich Anton , Sakovich Sergei , Turhan Refik
Published: July 2008

A new integrable sixth-order nonlinear wave equation is discovered by means of the Painlevé analysis, which is equivalent to the Korteweg–de Vries equation with a source. A Lax representation and an auto-Bäcklund transformation are found for the new equation, and its traveling wave solutions and generalized symmetries are studied.
Extracting the pair distribution function of liquids and liquid-vapor surfaces by grazing incidence x-ray diffraction mode
Authors: Vaknin David , Bu Wei , Travesset Alex
Published: July 2008

We show that the structure factor S(q) of water can be obtained from x-ray synchrotron experiments at grazing angle of incidence (in reflection mode) by using a liquid surface diffractometer. The corrections used to obtain S(q) self-consistently are described. Applying these corrections to scans at different incident beam angles (above the critical angle) collapses the measured intensities into a single master curve, without fitting parameters, which within a scale factor yields S(q). Performing the measurements below the critical angle for total reflectivity yields the structure factor of the top most layers of the water/vapor interface. Our results indicate water restructuring at the vapor/water interface. We also introduce a new approach to extract g(r), the pair distribution function (PDF), by expressing the PDF as a linear sum of error functions whose parameters are refined by applying a nonlinear least square fit method. This approach enables a straightforward determination of the inherent uncertainties in the PDF. Implications of our results to previously measured and theoretical predictions of the PDF are also discussed.
Correlation between plasticity and fragility in Mg-based bulk metallic glasses with modulated heterogeneity
Authors: Park E. S. , Lee J. Y. , Kim D. H. , Gebert A. , Schultz L.
Published: July 2008

A correlation between the kinetic fragility index (m) and enhanced plasticity is presented in Mg-based bulk metallic glasses (BMGs) with modulated heterogeneity by both suitable minor addition and optimal cooling rate. As case study, with minor addition of Gd in Mg65Cu7.5Ni7.5Zn5Ag5Y10−xGdx BMG, plasticity as well as glass-forming ability improves in a wide composition range (2.5≤x≤7.5 at. %). Furthermore, the cooling rate can affect the structural heterogeneity and the deformability of BMGs. With increasing diameters for the alloy x=5, the compressive fracture strain increases from 2.97% at d=1 mm up to 3.74% at d=2 mm and then largely decreases. In particular, the variation of heterogeneity, which can directly affect in the property of BMG, can be evaluated by comparing the m values reflecting the inherent structure of BMGs. This concept can be used as a means of guiding alloy design and processing to alleviate brittleness of BMGs.
Tuning of ungated plasmons by a gate in the field-effect transistor with two-dimensional electron channel
Authors: Popov V. V. , Koudymov A. N. , Shur M. , Polischuk O. V.
Published: July 2008

We show that voltage variations at a short gate can effectively tune higher-order ungated plasmon resonances in field-effect transistors (FETs). These higher-order ungated plasmon resonances may be excited by incoming terahertz radiation with much greater efficiency than the gated plasmon resonances. We calculate the spectra of the terahertz plasmon absorption in the frame of a rigorous electromagnetic approach, which allows us to estimate the radiation resistance. Based on the calculation results, we explain the behavior of different plasmon resonances in terms of the alternating-current FET equivalent circuit. The results may help design high performance plasmonic devices operating in the terahertz frequency range.
Numerical simulation of the Zeeman effect in neutral xenon from NIR diode-laser spectroscopy
Authors: Ngom Baïlo B. , Smith Timothy B. , Huang Wensheng , Gallimore Alec D.
Published: July 2008

We present a numerical method for simulating neutral xenon absorption spectra from diode-laser spectroscopy of the Zeeman-split 6S′[1/2]→6P′[1/2] line at 834.682 nm-air in a galvatron’s plasma. To simulate the spectrum, we apply a Voigt profile to a spectrum of σ-transition lines of even- and odd-numbered isotopes computed from anomalous Zeeman and nonlinear Zeeman hyperfine structure theories, respectively. Simulated spectra agree well with Zeeman-split spectra measured from 30 to 300 G. A commercial nonlinear least-squares solver (LSQNONLIN) returns field strengths and translational plasma kinetic temperatures that minimize the error between simulated and experimental spectra. This work is a preamble to computing magnetic field topology and the speed distribution of neutral xenon particles in the plume of a Hall thruster from diode laser-induced fluorescence.
Extension of linear-scaling divide-and-conquer-based correlation method to coupled cluster theory with singles and doubles excitations
Authors: Kobayashi Masato , Nakai Hiromi
Published: July 2008

This paper describes the extension of the linear-scaling divide-and-conquer (DC)-based correlation method to the coupled cluster with singles and doubles excitations (CCSD) theory. In this DC-CCSD method, the CCSD equations are solved for all subsystems including their buffer regions with the use of the subsystem orbitals, which are obtained by the DC–Hartree–Fock method. Then, the correlation energy of the total system is evaluated by summing up the subsystem contributions other than the buffer regions by the energy density analysis technique. Numerical applications demonstrate that the present DC-CCSD gives highly accurate results with drastically less computational costs with regard to the required computer memory, scratch-disk capacity, and calculation time.
The renormalization group and the implicit function theorem for amplitude equations
Authors: Kirkinis Eleftherios
Published: July 2008

This article lays down the foundations of the renormalization group (RG) approach for differential equations characterized by multiple scales. The renormalization of constants through an elimination process and the subsequent derivation of the amplitude equation [Chen et al., Phys. Rev. E 54, 376 (1996)] are given a rigorous but not abstract mathematical form whose justification is based on the implicit function theorem. Developing the theoretical framework that underlies the RG approach leads to a systematization of the renormalization process and to the derivation of explicit closed-form expressions for the amplitude equations that can be carried out with symbolic computation for both linear and nonlinear scalar differential equations and first order systems but independently of their particular forms. Certain nonlinear singular perturbation problems are considered that illustrate the formalism and recover well-known results from the literature as special cases.
Supersensitive linear piezoresistive property in carbon nanotubes∕silicone rubber nanocomposites
Authors: Dang Zhi-Min , Jiang Mei-Juan , Xie Dan , Yao Sheng-Hong , Zhang Li-Qun , Bai Jinbo
Published: July 2008

High-elasticity carbon nanotube∕methylvinyl silicone rubber (CNT∕VMQ) nanocomposite with a markedly sensitive linear piezoresistive behavior is fabricated by dispersing conductive multiwall carbon nanotubes (MWCNTs) with different aspect ratios (AR=50 and 500) into rubber matrix homogeneously. We disclose that the percolation threshold of the nanocomposites with MWCNTs at AR=50 is abnormally lower than that at AR=500; extremely sensitive positive-pressure coefficient effect of the resistance and excellent cyclic compression under low pressure are also observed in the MWCNT∕VMQ nanocomposite with AR=50 MWCNTs at relatively low loading. These properties might originate from the special microstructure in the nanocomposites with AR=50 MWCNTs. The high-elasticity nanocomposite is very attracting for online compression stress monitoring in future engineering applications.
Shear band melting and serrated flow in metallic glasses
Authors: Georgarakis K. , Aljerf M. , Li Y. , LeMoulec A. , Charlot F. , Yavari A. R. , Chornokhvostenko K. , Tabachnikova E. , Evangelakis G. A. , Miracle D. B. , Greer A. L. , Zhang T.
Published: July 2008

Scanning electron microscopy observations of shear steps on Zr-based bulk metallic glasses show direct evidence of shear band melting due to heat generated by elastic energy release. The estimated range of attained temperatures and the observed morphologies are consistent with shear steps forming at a subsonic speed limited by a required redistribution of local microscopic stresses. The calculations indicate that a 0.2μm layer melts in the vicinity of a shear band forming a 1μm shear step. The plastic part of the stress strain curve is serrated but a majority of shear events are not associated to serrations.
Stretched-exponential a-Si:H∕c-Si interface recombination decay
Authors: De Wolf Stefaan , Olibet Sara , Ballif Christophe
Published: July 2008

The electronic properties of hydrogenated amorphous silicon (a-Si:H) relax following stretched exponentials. This phenomenon was explained in the past by dispersive hydrogen diffusion, or by retrapping included hydrogen motion. In this letter, the authors report that the electronic passivation properties of intrinsic a-Si:H/crystalline silicon (c-Si) interfaces relax following a similar law. Carrier injection dependent a-Si:H∕c-Si interface recombination calculations suggest this originates from amphoteric interface state (or Si dangling bond) reduction, rather than from a field effect. These findings underline the similarity between a-Si:H∕c-Si interface recombination and the electronic properties of a-Si:H bulk material.
Particle competition for complex network community detection
Authors: Quiles Marcos G. , Zhao Liang , Alonso Ronaldo L. , Romero Roseli A. F.
Published: July 2008

In many real situations, randomness is considered to be uncertainty or even confusion which impedes human beings from making a correct decision. Here we study the combined role of randomness and determinism in particle dynamics for complex network community detection. In the proposed model, particles walk in the network and compete with each other in such a way that each of them tries to possess as many nodes as possible. Moreover, we introduce a rule to adjust the level of randomness of particle walking in the network, and we have found that a portion of randomness can largely improve the community detection rate. Computer simulations show that the model has good community detection performance and at the same time presents low computational complexity.
Hexagonal ferrites for use in microwave notch filters and phase shifters
Authors: Fal T. J. , Camley R. E.
Published: July 2008

Recently there has been interest in small, planar, high frequency (10–50 GHz) signal processing devices which are based on metallic ferromagnets. This paper, in contrast, presents theoretical results for devices utilizing a hexagonal ferrite. The notch filter results show attenuation of frequencies in the 40–60 GHz range with applied fields in the 1–5 kOe range. For geometries similar to the ultrasmall metallic devices, the transmission loss at the notch can be from 20 to 140 dB/cm depending on the thickness of the hexagonal ferrite film and the inclusion of dielectric spacers. The phase shifter results show phase shifts of up to 360°, with losses below 2 dB/cm. These results are obtained for devices using thin films around 1 μm in thickness for the hexagonal ferrite, and for reasonable linewidths below 200 Oe.
High-resolution nanofabrication using a highly focused electron beam
Authors: Aref Thomas , Remeika Mikas , Bezryadin Alexey
Published: July 2008

A highly focused electron beam can be used to shape nanodevices. We demonstrate electron beam etching of nanoholes through multiwalled carbon nanotubes (MWNTs) and niobium nanowires. Nanoholes, as small as ∼2.5 nm in diameter, can be reproducibly fabricated. This technique can also be used to fabricate constrictions and larger nanoholes in MWNTs. We argue that with some improvement, this technique might be used to pattern suspended graphene by the removal of targeted single atoms.
Spherical indentation of a finite poroelastic coating
Authors: Galli M. , Oyen M. L.
Published: July 2008

Indentation testing of a finite poroelastic layer is considered. Finite element modeling was used to investigate spherical contact creep tests, with emphasis on the influence of layer thickness and of finite rise time on the time-dependent deformation. Thin layers are stiffened by the substrate constraint even at very small relative indenter penetrations and reach steady state more quickly than thick layers. The degree of consolidation following loading is affected by the interaction of layer thickness and rise time and cannot be predicted from either alone. These results provide guidance for micro- and nanoindentation testings of hydrogel coatings for biomedical applications.
Polymorphic transformation from body-centered to face-centered cubic vanadium metal during mechanosynthesis of nanostructured vanadium nitride determined by extended x-ray absorption fine structure spectroscopy
Authors: López-Flores Víctor , Roldán Manuel A. , Real Concepción , Páez Adela Muñoz , Castro Germán R.
Published: July 2008

The pathway for vanadium nitride (VN) formation obtained by milling treatment has been traced out. At the initial stages of the process, the reactant, vanadium metal, showing body-centered cubic (bcc) structure, becomes highly distorted. Simultaneously, the formation of a small nucleus of the product, VN, takes place. X-ray absorption spectroscopy (XAS) has allowed the quantification of the distortion degree as well as the detection of the VN nucleus in the early stages of their formation, while other standard structural characterization techniques are unable to detect such phenomena. For increasing milling times, apart from the expected increase in the size of the VN nucleus, a polymorphic transformation from bcc to fcc vanadium metal has been recorded. This phase might play a key role in the overall synthesis process and could be a reaction intermediate in other solid state processes involving V metal. The sensitivity of XAS to noncrystalline domains and to highly distorted environments, as well as the use of high resolution x-ray diffraction, has provided the relevant information to understand the whole reaction process.
Diffusion and activation of n-type dopants in germanium
Authors: Koike Masahiro , Kamata Yoshiki , Ino Tsunehiro , Hagishima Daisuke , Tatsumura Kosuke , Koyama Masato , Nishiyama Akira
Published: July 2008

The diffusion and activation of n-type impurities (P and As) implanted into p-type Ge(100) substrates were examined under various dose and annealing conditions. The secondary ion mass spectrometry profiles of chemical concentrations indicated the existence of a sufficiently high number of impurities with increasing implanted doses. However, spreading resistance probe profiles of electrical concentrations showed electrical concentration saturation in spite of increasing doses and indicated poor activation of As relative to P in Ge. The relationships between the chemical and electrical concentrations of P in Ge and Si were calculated, taking into account the effect of incomplete ionization. The results indicated that the activation of P was almost the same in Ge and Si. The activation ratios obtained experimentally were similar to the calculated values, implying insufficient degeneration of Ge. The profiles of P in Ge substrates with and without damage generated by Ge ion implantation were compared, and it was clarified that the damage that may compensate the activated n-type dopants has no relationship with the activation of P in Ge.
Experimental study of a hybrid single flux quantum digital superconducting quantum interference device magnetometer
Authors: Reich Torsten , Febvre Pascal , Ortlepp Thomas , Uhlmann F. Hermann , Kunert Juergen , Stolz Ronny , Meyer Hans-Georg
Published: July 2008

Digital superconducting quantum interference devices (SQUIDs) have been proposed to extend the dynamic range of analog SQUIDs whenever magnetic fields varying in a wide range need to be measured. We developed a digital SQUID concept, based on the single flux quantum technique, using the reliable 1 kA/cm2 niobium trilayer technology of the FLUXONICS Foundry. We present an extensive experimental analysis to evaluate the digital SQUID magnetometer operation in shielded and unshielded conditions. Bit error rate measurements have shown reliable operation of the digital superconducting circuitry with operation margins of ±11%, confirmed by stable operation in unshielded magnetometer mode for more than 10 h. The best intrinsic magnetic field resolution, corresponding to one magnetic single flux quantum (Φ0), was found to be about 4.2 nT. Peak-to-peak amplitudes of 14 800 and 2810 flux quanta Φ0 could be measured, respectively, for inductively coupled current and magnetic field inputs. A flux noise level of 220 mΦ0/Hz at 0.1 Hz has been measured, corresponding to a dynamic range of 76 dB (e.g., above 12 bits). Furthermore, preliminary experiments have shown that the integration of a digital SQUID with an analog dc SQUID in a hybrid magnetometer is a solution to reach simultaneously a high dynamic range and an increased field sensitivity. Such a device is of utmost importance to detect magnetic fields with high dynamic range to monitor earthquakes in the presence of high amplitude external magnetic perturbations.
Unusual surface reliefs from photoinduced creeping and aggregation behavior of azopolymer
Authors: Lee Seungwoo , Jeong Yong-Cheol , Park Jung-Ki
Published: July 2008

We report the spontaneous formation of unusual surface reliefs, in which two sets of sinusoidal gratings were hierarchically structured, merely by single-step holographic inscription on amorphous azopolymer films. By monitoring of growth behavior of surface reliefs during holographic inscription, we found that the formation of additional grating is caused by the creeping and resulting aggregation of dome structures. Our direct observation of creeping and aggregation behavior is expected to contribute to enhancing the understanding of unusual surface reliefs, and also in fabricating complex surface reliefs.
Separation of electronic and ionic conductivity in mixed conductors from the ac response: Application to Pr0.56Bi0.04Li0.2TiO3
Authors: García-Sánchez Mario-Fidel , Fernández Nestor , Martínez-Sarrión María-Luisa , Mestres Lourdes , Fernández-Gutierrez Floiran , Santana Guillermo , Ruiz-Salvador A. Rabdel
Published: July 2008

A method has been developed for separation of ionic and electronic conductivity in mixed conductors. The procedure is accomplished by using blocking electrodes and the Kramers–Kronig relations for separating the dc conductivity from total response. This method was applied to lithium inserted and deinserted sample of Pr0.56Bi0.04Li0.2TiO3. This material is an ionic conductor, and after insertion, electronic conduction appears in the sample. The deinserted sample has a similar electric behavior to the original material. This method does not need any previous model when processing the data. Hence, it avoids those modeling related mistakes and increases the possibilities of dielectric spectroscopy.
Identification of deep trap levels from thermally stimulated current spectra of semi-insulating CdZnTe detector material
Authors: Pavlović M. , Jakšić M. , Zorc H. , Medunić Z.
Published: July 2008

Deep trap levels in the semi-insulating (SI) CdZnTe detector material were characterized by simultaneous multiple peak analysis based on thermally stimulated current (TSC) measurements. In our TSCs that have been published previously electron hole pairs were created through the use of proton beam irradiation. Charge carriers were captured in deep traps and afterward released by thermal emission, which was recorded in the 90–300 K range. We showed that the obtained TSC spectra could be well fitted with a unique set of 14 different deep traps, which were all simultaneously and completely characterized. The obtained trap data are in good accordance with earlier deep trap characterizations of the other authors obtained on similar SI CdZnTe materials using different methods.
A high speed, postprocessing free, quantum random number generator
Authors: Dynes J. F. , Yuan Z. L. , Sharpe A. W. , Shields A. J.
Published: July 2008

A quantum random number generator (QRNG) based on gated single photon detection of an In–GaAs photodiode at gigahertz frequency is demonstrated. Owing to the extremely long coherence time of each photon, each photons’ wave function extends over many gating cycles of the photodiode. The collapse of the photon wave function on random gating cycles as well as photon random arrival time detection events are used to generate sequences of random bits at a rate of 4.01Mbit∕s. Importantly, the random outputs are intrinsically biasfree and require no postprocessing procedure to pass random number statistical tests, making this QRNG an extremely simple device.
Thin film NiTi coatings on optical fiber Bragg sensors
Authors: Mohanchandra K. P. , Karnani S. , Emmons M. C. , Richards W. L. , Carman G. P.
Published: July 2008

This paper describes the sputter deposition and characterization of nickel titanium (NiTi) thin film shape memory alloy onto the surface of an optical fiber Bragg grating. The NiTi coating uniformity, crystallinity, and transformation temperatures are measured using scanning electron microscope, x-ray diffraction, and differential scanning calorimeter, respectively. The strain in the optical fiber is measured using centroid calculation of wavelength shifts. Results show distinct and abrupt changes in the optical fiber signal with the four related transformation temperatures represented by the austenite-martensite forward and reverse phase transformations. These tests demonstrate a coupling present between optical energy and thermal energy, i.e., a modified multiferroic material.
Isotope disorder of phonons in GaN and its beneficial effect on high power field effect transistors
Authors: Khurgin Jacob B. , Jena Debdeep , Ding Yujie J.
Published: July 2008

We analyze the influence of isotope disorder on longitudinal optical (LO) phonon modes in GaN and then study the scattering by disordered LO phonons in the channel of high power transistor. Results indicate that as a larger number of LO phonons gets excited, a more efficient cooling of electrons can be accomplished and most of the spurious hot phonon effects can be mitigated leading to significant improvement in the saturation velocity. To the best of our knowledge this is the first ever example of disorder playing constructive role in the performance of room-temperature electronic devices.
Scanning optical probe microscopy with submicrometer resolution using an organic photodetector
Authors: An Kwang H. , O’Connor Brendan , Pipe Kevin P. , Zhao Yiying , Shtein Max
Published: July 2008

A high-resolution scanning optical microscopy technique is demonstrated, in which an organic photodetector on a silicon-based scanning probe cantilever scans a sample, simultaneously recording optical and topographic data with submicrometer resolution, while showing no measurable degradation during the scan. Potential applications of the probe include characterization of optoelectronic materials and devices, as well as simultaneous topographic and fluorescence microscopy of biological samples. Extension to these applications is aided by the fact that the probe is compatible with conventional atomic force microscopy systems and does not suffer some of the practical difficulties of existing near-field scanning optical microscopy systems.
Critical fields and anisotropy of NdFeAsO0.82F0.18 single crystals
Authors: Jia Ying , Cheng Peng , Fang Lei , Luo Huiqian , Yang Huan , Ren Cong , Shan Lei , Gu Changzhi , Wen Hai-Hu
Published: July 2008

By using flux method, we have grown single crystals of NdFeAsO0.82F0.18 at ambient pressures. Resistive measurements reveal a surprising discovery that the anisotropy Γ=(mc∕mab)1∕2 is below 5, which is much smaller than the theoretically calculated value. The data measured up to 400K show a curved feature, which prevents a conjectured linear behavior for an unconventional metal. The upper critical fields determined based on the Werthamer–Helfand–Hohenberg formula [N. R. Werthamer et al., Phys. Rev. 147, 295 (1966)] are Hc2ab(T=0K)≈304T and Hc2c(T=0K)≈62–70T. These high values indicate very encouraging applications of the new superconductors.
On the width of the recombination zone in ambipolar organic field effect transistors
Authors: Kemerink M. , Charrier D. S. H. , Smits E. C. P. , Mathijssen S. G. J. , de Leeuw D. M. , Janssen R. A. J.
Published: July 2008

The performance of organic light emitting field effect transistors is strongly influenced by the width of the recombination zone. We present an analytical model for the recombination profile. By assuming Langevin recombination, the recombination zone width W is found to be given byW=4.34dδ, with d and δ the gate dielectric and accumulation layer thicknesses, respectively. The model compares favorably to both numerical calculations and measured surface potential profiles of an actual ambipolar device.
Transient carrier transfer in tunnel injection structures
Authors: Talalaev V. G. , Tomm J. W. , Zakharov N. D. , Werner P. , Gösele U. , Novikov B. V. , Sokolov A. S. , Samsonenko Y. B. , Egorov V. A. , Cirlin G. E.
Published: July 2008

InGaAs tunnel injection nanostructures consisting of a single quantum well as injector and a quantum dot layer as emitter are studied by time-resolved photoluminescence spectroscopy. The quantum dot photoluminescence undergoes substantial changes when proceeding from direct quantum dot excitation to quantum well excitation, which causes an indirect population of the dot ground states. This results in a lowered effective carrier temperature within the dots. Results on the carrier transfer versus barrier thickness are discussed within the Wentzel–Kramers–Brillouin approximation. Deviations for barrier thicknesses <5nm are assigned to the formation of nanobridges that are actually detected by transmission electron microscopy.
Real-time optical reflectometry enabled by amplified dispersive Fourier transformation
Authors: Goda Keisuke , Solli Daniel R. , Jalali Bahram
Published: July 2008

The axial scan rate of optical frequency-domain reflectometry and optical coherence tomography can be increased to megahertz frequencies by dispersive Fourier transformation. However, the fundamental connection between dispersion and loss creates a trade-off between detection sensitivity and acquisition speed. Here we circumvent this predicament by using distributed Raman postamplification of the reflection from the sample. The Raman amplification enables measurement of weak signals, which are otherwise buried in detector noise. It extends the depth range without sacrificing the acquisition speed. Single-shot imaging with improved sensitivity at an axial scan rate of 36.6MHz is demonstrated.
Control of threshold voltage in ZnO-based oxide thin film transistors
Authors: Park Jin-Seong , Jeong Jae Kyeong , Mo Yeon-Gon , Kim Hye Dong , Kim Chang-Jung
Published: July 2008

We investigated the feasibility of controlling the threshold voltage (Vth) by adjusting the thickness of the active layer (tactive) rather than by conventional chemical doping in indium-gallium-zinc oxide (IGZO) transistors with an inverted staggered structure. The value of Vth of the IGZO transistor was linearly modulated from −15.3±1.6to−0.1±0.21V by reducing tactive without any significant change in the field-effect mobility (μFE), subthreshold gate swing, or Ion∕off ratio. The free electron density extracted from the relationship between tactive and Vth was 1.9×1017cm−3, which was consistent with the value of 1.5×1017cm−3 obtained from the C-V measurement for the 30-nm-thick IGZO films. The slight increase in the μFE with increasing tactive, which was in contradiction with the behavior of the corresponding amorphous Si transistor, was explained by the anomalous behavior of the source/drain contact resistance.
Formation of a manganese oxide barrier layer with thermal chemical vapor deposition for advanced large-scale integrated interconnect structure
Authors: Neishi Koji , Aki Shiro , Matsumoto Kenji , Sato Hiroshi , Itoh Hitoshi , Hosaka Shigetoshi , Koike Junichi
Published: July 2008

Advanced large-scale integrated interconnect structure faces a major challenge in forming a thin and conformal diffusion barrier layer. We deposited a Mn oxide layer by thermal chemical vapor deposition (CVD) on SiO2 substrates and investigated deposition behavior and diffusion barrier property. A thin Mn oxide layer was formed with a uniform thickness of 2.6–10nm depending on deposition temperature between 100 and 400°C. Heat-treated samples of Cu/CVD-Mn oxide/SiO2 indicated no interdiffusion at 400°C for 100h. The CVD of the Mn oxide layer was found to be an excellent barrier formation process.
High-temperature annealing behavior of deep levels in 1MeV electron irradiated p-type 6H-SiC
Authors: Alfieri Giovanni , Kimoto Tsunenobu
Published: July 2008

We report on the thermal stability of deep levels detected after 1MeV electron irradiated p-type 6H-SiC. The investigation was performed by deep level transient spectroscopy, and an isochronal annealing series was carried out in the 373–2073K temperature range. We found seven traps located between 0.23 and 1.3eV above the valence band edge (EV). Two traps anneal out at temperatures below 1273K, while the others display a high thermal stability up to 2073K. The nature of the detected traps is discussed on the basis of their annealing behavior and previous data found in the literature.
Ti/Al/Mo/Au Ohmic contacts to all-binary AlN/GaN high electron mobility transistors
Authors: Wang Liang , Adesida Ilesanmi , Dabiran Amir M. , Wowchak Andrew M. , Chow Peter P.
Published: July 2008

Electrical and microstructural characterizations of the Ti/Al/Mo/Au Ohmic contacts to ultrathin AlN/GaN heterostructures were carried out. It was found that as-deposited contacts had linear I-V behavior due to high tunneling current across the thin AlN barrier. A contact resistance of 0.455 Ω mm was obtained for samples annealed at 800 °C without any premetallization plasma treatment. Transmission electron microscopy studies showed that despite the use of Ti, the AlN layer remained intact. Mushroom-shaped TiN protrusions were formed only along threading dislocations, which terminated in the AlN layer. The TiN protrusions acted as metal plugs/spikes thereby aiding carrier transport.