bluuebunny/crossref_metadata_2025 huggingface dataset:
Markers of Inflammation and Weight Change in Middle‐Aged Adults: Results From the Prospective MONICA/KORA S3/F3 Study
Authors: Holz Thomas , Thorand Barbara , Döring Angela , Schneider Andrea , Meisinger Christine , Koenig Wolfgang
Published: April 2010

We investigated associations of markers of inflammation such as albumin, fibrinogen, C‐reactive protein (CRP), and white blood cell count (WBCC) with future weight gain and weight loss in middle‐aged adults in order to further elucidate the relationship between subclinical inflammation and weight change. Data were derived from the third population‐based MONICA (Monitoring of Trends and Determinants in Cardiovascular Diseases) Augsburg survey (S3) conducted as part of the multinational World Health Organization MONICA project in 1994–1995 and a follow‐up examination, to which all eligible subjects from S3 were invited in 2004–2005 (F3). In total, 2,792 persons (1,391 men, 1,401 women) aged 25–74 years at baseline were analyzed. Subjects with elevated concentrations of inflammatory markers were more prone to gain weight during follow‐up. The odds ratios (OR) for a large mean annual weight gain (i.e., on average 1.02 kg/year) was 1.73 (95% confidence interval (CI) 1.27, 2.35) in fully adjusted analyses for subjects in the highest compared to the lowest quartile of fibrinogen. The respective ORs were 1.45 (95% CI, 1.08, 1.94) and 1.37 (95% CI, 1.03, 1.82) for CRP and WBCC. Stratified analyses revealed that associations were strongest among subjects who quitted smoking during the follow‐up period (new quitters). Associations of inflammatory markers with large mean annual weight loss were weaker and became nonsignificant after multivariable adjustment. In conclusion, elevated levels of inflammatory markers are independently associated with weight gain in middle‐aged adults, particularly among new quitters. This suggests that inflammation plays a key role in the process of weight gain, especially after smoking cessation.
Cold‐Induced Adaptive Thermogenesis in Lean and Obese
Authors: Wijers Sander L.J. , Saris Wim H.M. , Lichtenbelt Wouter D. van Marken
Published: April 2010

On entering a cold environment, people react by increasing insulation and energy expenditure (EE). However, large interindividual differences exist in the relative contribution of each mechanism. Short‐term studies revealed that obese subjects increase EE (i.e., adaptive thermogenesis) less than lean subjects, which might have implications for the predisposition to obesity. In this study, we validate the differences in adaptive thermogenesis between lean and obese upon midterm mild cold exposure. Therefore, 10 lean and 10 obese subjects were exposed for 48 h to mild cold (16 °C) in a respiration chamber. The preceding 36 h they stayed in the same chamber at a neutral temperature (22 °C) for the baseline measurements. EE, physical activity, skin temperature, and core temperature have been measured for the last 24 h of both parts. Mean daytime EE increased significantly in the lean subjects (P < 0.01), but not in the obese. Physical activity decreased significantly in the lean (P < 0.01) and the obese (P < 0.001) subjects. The change in EE was related to the change in physical activity in both groups (respectively R2 = 0.673, P < 0.01 and R2 = 0.454, P < 0.05). Upon mild cold exposure, lean subjects decreased proximal skin temperature less, but distal skin temperature more than obese. In conclusion, the interindividual differences in cold‐induced thermogenesis were related to changes in physical activity in both lean and obese, pointing at the existence of individual variation in physical activity to compensate for cold‐induced thermogenesis. Furthermore, although a large part of the lean subjects counteracted the cold by increasing EE, most obese subjects changed temperature distribution, and therefore, increased insulation.
Preschool Speech, Language Skills, and Reading at 7, 9, and 10 Years: Etiology of the Relationship
Authors: Hayiou-Thomas Marianna E. , Harlaar Nicole , Dale Philip S. , Plomin Robert
Published: April 2010

Purpose

To examine the etiology of the relationship between preschool speech and language, and later reading skills.

Method

One thousand six hundred seventy-two children from the Twins Early Development Study (B. R. Oliver & R. Plomin, 2007) were given a comprehensive speech and language assessment at 4½ years. Reading was assessed at 7, 9, and 10 years. Twin analyses were applied to the data to assess the contributions of genetic and environmental factors to the longitudinal relationships between speech and reading, and language and reading.

Results

Phenotypically, there is a moderate and stable relationship between 4½-year speech and language scores and reading at 7, 9, and 10 years. Etiologically, at the individual-differences level, both genetic and shared environmental factors contribute to the links between language skills and reading. By contrast, genetic factors account for most of the relationship between early speech and later reading. At the extremes, there appears to be an even stronger role for genetic factors in accounting for the prediction from early speech and language impairments to later reading outcome.

Conclusion

Both genetic and environmental factors contribute to the relationship between early language skills and reading, whereas genetic factors play a dominant role in the relationship between early speech and reading.
Production of Tense Morphology by Afrikaans-Speaking Children With and Without Specific Language Impairment
Authors: Southwood Frenette , van Hout Roeland
Published: April 2010

Purpose

To establish whether the predictions of the extended optional infinitive (EOI) hypothesis (Rice, Wexler, & Cleave, 1995) hold for the language of Afrikaans-speaking children with specific language impairment (SLI) and whether tense marking is a possible clinical marker of SLI in Afrikaans.

Method

Production of tense morphology was examined in 3 groups of Afrikaans-speaking children—15 with SLI who were 6 years old, 15 typically developing (TD) 4-year-olds matched on mean length of utterance, and 15 TD 6-year-olds—using both elicited and spontaneously produced verb forms.

Results

On the sentence completion task, children with SLI fared on par with 4-year-olds and worse than age-matched peers. However, in terms of spontaneous production of morphemes pertaining to tense, children with SLI fared worse than both TD groups. Furthermore, children with SLI mostly made the same types of errors as 4-year-olds, although some errors were unique to the SLI group. Most errors entailed omissions, of modal and temporal auxiliaries as well as of copula
be
.

Conclusion

The errors offer support for the EOI hypothesis. Tense marking has the potential to be a clinical marker of SLI in Afrikaans, but further research with larger groups of Afrikaans-speaking children, including children of other ages, is needed to confirm this.
Randomized Comparison of Augmented and Nonaugmented Language Interventions for Toddlers With Developmental Delays and Their Parents
Authors: Romski MaryAnn , Sevcik Rose A. , Adamson Lauren B. , Cheslock Melissa , Smith Ashlyn , Barker R. Michael , Bakeman Roger
Published: April 2010

Purpose

This study compared the language performance of young children with developmental delays who were randomly assigned to 1 of 3 parent-coached language interventions. Differences in performance on augmented and spoken word size and use, vocabulary size, and communication interaction skills were examined.

Method

Sixty-eight toddlers with fewer than 10 spoken words were randomly assigned to augmented communication input (AC-I), augmented communication output (AC-O), or spoken communication (SC) interventions; 62 children completed the intervention. This trial assessed the children’s symbolic language performance using communication measures from the language transcripts of the 18th and 24th intervention sessions and coding of target vocabulary use.

Results

All children in the AC-O and AC-I intervention groups used augmented and spoken words for the target vocabulary items, whereas children in the SC intervention produced a very small number of spoken words. Vocabulary size was substantially larger for AC-O and AC-I than for SC groups.

Conclusions

This study found that augmented language interventions that include parent coaching have a positive communication effect on young children with developmental delays who begin with fewer than 10 spoken words. Clinical implications suggest that augmented communication does not hinder, and actually aids, speech production abilities in young children with developmental delays.
A Treatment Sequence for Phonological Alexia/Agraphia
Authors: Beeson Pélagie M. , Rising Kindle , Kim Esther S. , Rapcsak Steven Z.
Published: April 2010

Purpose

Damage to left perisylvian cortex often results in impaired phonological processing abilities with written language profiles consistent with phonological alexia and phonological agraphia. The purpose of this article was to examine a behavioral treatment sequence for such individuals intended to strengthen phonological processing and links between phonology and orthography, as well as train a means to maximize use of residual orthographic and phonological knowledge for spelling.

Method

Two women with persistent impairments of written language and phonological processing following damage to left perisylvian cortical regions participated in this study. Both exhibited characteristic features of phonological alexia and agraphia in that reading and spelling performance for real words was better preserved than nonwords (lexicality effect). A 2-stage treatment protocol was administered to strengthen sublexical skills (phonological treatment) and to train interactive use of lexical and sublexical information to maximize spelling performance (interactive treatment).

Results

Both participants improved phonological processing abilities and reading/spelling via the sublexical route. They also improved spelling of real words and were able to detect and correct most residual errors using an electronic spelling aid.

Conclusions

Behavioral treatment served to strengthen phonological skills supporting reading and spelling, and provided a functional compensatory strategy to overcome residual weaknesses.
Le contrôle de plaque, un élément essentiel du
succès du traitement orthodontique
Authors: Dersot Jean-Marc
Published: April 2010

C'est parce que les tissus parodontaux, et plus particulièrement le
desmodonte, existent que l'orthodontiste peut envisager le déplacement
dentaire provoqué. Dans un souci d'intégrer la notion de
coût/bénéfice/sécurité, l'orthodontiste se doit de
prévenir, de réduire et/ou d'éviter les effets
délétères de ses traitements sur les tissus parodontaux.
L'inflammation gingivale à forte composante hyperplasique, les pertes
d'attache, l'alvéolyse et la résorption radiculaire peuvent
entraîner, en valeur absolue, une réduction des structures
parodontales de soutien. La clé de la prévention de ces
problèmes réside dans le contrôle de plaque, phase trop souvent
bâclée, voire négligée. Le challenge, avant tout traitement
orthodontique, aussi bien chez l'enfant que chez l'adulte, est de changer le
comportement du patient face à sa cavité buccale et à la plaque
bactérienne. L'objectif de cet article est de parcourir la
littérature fondée sur les preuves (revues systématiques,
méta-analyses), d'apporter des éléments de réflexion et des
propositions concrètes pour résoudre définitivement cette phase
essentielle de tout traitement orthodontique qu'est la motivation, phase qui
peut aussi être réalisée par des « auxiliaires de santé ».
Rapports réciproques entre orthodontie et parodontologie. Intérêt d'une synergie d'action effective
Authors: Ngom Papa Ibrahima , Benoist Henri Michel , Soulier-Peigue Delphine , Niang Awa
Published: April 2010

L'objectif de cette revue de littérature est de faire le point sur les rapports réciproques entre l'orthodontie et la parodontologie. Un des fondements rationnels de notre discipline est que des relations intra- et inter-arcades normales sont un préalable anatomique et fonctionnel dans la préservation d'une denture saine. Certaines dysmorphoses orthodontiques sont ainsi associées à des difficultés à maintenir une bonne hygiène avec une gingivite et potentiellement une parodontite comme possibles conséquences. De la même façon, l'alignement correct des dents dans leurs arcades respectives et l'établissement de relations inter-arcades normales que procurent les traitements orthodontiques facilitent le maintien de l'hygiène et le contrôle de l'inflammation parodontale. D'un autre côté, les dispositifs orthodontiques par leur présence constituent de véritables pièges à plaque et contribuent de ce fait au risque local de maladie parodontal. Les parodontites sont des maladies infectieuses inflammatoires d'origine bactérienne provoquant une perte du support osseux et ligamentaires des dents. Elles sont accompagnées de troubles esthétiques et fonctionnels dus au processus pathologique lui-même (déplacements dentaires pathologiques, recession gingivale, mobilités dentaires) ou aux séquelles laissées par le traitement parodontal. L'orthodontie peut contribuer à la prise en charge de ces problèmes esthétiques et fonctionnels. Sa mise en œuvre requiert néanmoins un contrôle préalable de la progression de la maladie parodontale et une bonne connaissance de la biomécanique spécifique du déplacement orthodontique des dents au parodonte réduit. Les résultats à court terme et long terme montrent l'efficacité de la synergie d'action entre orthodontie et parodontie.
Détection et thérapeutique des troubles
temporo-mandibulaires en orthodontie
Authors: Bocquet Emmanuelle , Moreau Alexis , Danguy Michel , Danguy Chantal
Published: April 2010

L'orthodontiste est confronté chaque jour à des troubles de
l'occlusion, dont la prise en charge lui est habituelle. En revanche, la
gestion de troubles temporo-mandibulaires est moins évidente, que ce
soit au niveau détection, diagnostic ou prise en charge
thérapeutique.
Aussi, une connaissance approfondie de l'anatomo-physiologie de
l'articulation temporo-mandibulaire, de ses mécanismes d'action est
indispensable pour permettre au praticien de détecter et diagnostiquer
les différentes pathologies résultant de phénomènes
étiologiques variés.
Le diagnostic rigoureux, au moyen d'un examen clinique approfondi et
d'examens complémentaires axiographiques et radiologiques, du
dysfonctionnement temporo-mandibulaire et de ses étiologies (notamment
dento-alvéolaires et occlusales) permettra de mettre en place une
thérapeutique appropriée, qu'elle soit orthodontique pure, ou en
collaboration avec des confrères d'autres disciplines (occlusodontiste,
chirurgien, ostéopathe...).
Le traitement orthodontique peut-il générer des algies
et/ou dysfonctionnements articulaires ou musculaires
(ADAM) ? Une revue de littérature
Authors: Gebeile-Chauty Sarah , Robin Olivier , Messaoudi Yassine , Aknin Jean-Jacques
Published: April 2010

Longtemps considérée comme fortement
responsable des algies et/ou dysfonctionnements articulaires ou musculaires
(ADAM), l'occlusion est aujourd'hui considérée comme un des facteurs
participant à l'étiologie, parmi d'autres.
Les études récentes, revues de littérature ou méta-analyses,
études longitudinales avec suivi d'enfants traités sur plusieurs
années, concluent à l'absence de risque pour un traitement
orthodontique de déclencher des ADAM. L'apparition de signes d'ADAM au
cours d'un traitement orthodontique doit être replacée dans le
contexte épidémiologique caractérisé par une forte
augmentation de leur prévalence au cours de la période de
l'adolescence.
En conclusion, si les traitements orthodontiques ne peuvent être
considérés comme des facteurs étiopathogéniques
avérés des ADAM, il n'existe pas, à l'inverse, d'arguments
scientifiques permettant de justifier l'indication de traitements
orthodontiques dans le seul but de traiter les ADAM.
Generating chaos for discrete time-delayed systems via impulsive control
Authors: Guan Zhi-Hong , Liu Na
Published: April 2010

Generating chaos for a class of discrete time-delayed systems via impulsive control is investigated in this paper. With the augmented matrix method, the time-delay impulsive systems can be transformed into a new class of linear discrete impulsive systems. Based on the largest Lyapunov exponent and the boundedness of the systems, some theoretical results about the chaotification for the discrete impulsive systems with time delay are derived and an example is given to visualize the satisfactory control performance.
High vacuum cells for classical surface techniques
Authors: Martinez Imee Su , Baldelli Steven
Published: April 2010

Novel glass cells were designed and built to be able to perform surface potential and surface tension measurements in a contained environment. The cells can withstand pressures of approximately 1×10−6 Torr, providing a reasonable level of control in terms of the amounts of volatile contaminants during experimentation. The measurements can take several hours; thus the cells help maintain the integrity of the sample in the course of the experiment. To test for the feasibility of the cell design, calibration measurements were performed. For the surface potential cell, the modified TREK 6000B-7C probe exhibited performance comparable to its unmodified counterpart. The correlation measurements between applied potential on the test surface and the measured potential showed R-values very close to 1 as well as standard deviation values of less than 1. Results also demonstrate improved measurement values for experiments performed in vacuum. The surface tension cell, on the other hand, which was used to perform the pendant drop method, was tested on common liquids and showed percentage errors of 0.5% when compared to literature values. The fabricated cells redefine measurements using classical surface techniques, providing unique and novel methods of sample preparation, premeasurement preparation, and sample analysis at highly beneficial expenditure cost.
Dielectrophoretic spectra of translational velocity and critical frequency for a spheroid in traveling electric field
Authors: Bunthawin Sakshin , Wanichapichart Pikul , Tuantranont Adisorn , Coster Hans G. L.
Published: April 2010

An analysis has been made of the dielectrophoretic (DEP) forces acting on a spheroidal particle in a traveling alternating electric field. The traveling field can be generated by application of alternating current signals to an octapair electrode array arranged in phase quadrature sequence. The frequency dependent force can be resolved into two orthogonal forces that are determined by the real and the imaginary parts of the Clausius–Mossotti factor. The former is determined by the gradient in the electric field and directs the particle either toward or away from the tip of the electrodes in the electrode array. The force determined by the imaginary component is in a direction along the track of the octapair interdigitated electrode array. The DEP forces are related to the dielectric properties of the particle. Experiments were conducted to determine the DEP forces in such an electrode arrangement using yeast cells (Saccharomyces cervisiate TISTR 5088) with media of various conductivities. Experimental data are presented for both viable and nonviable cells. The dielectric properties so obtained were similar to those previously reported in literature using other DEP techniques.
Static spherically symmetric solutions of the SO(5) Einstein Yang–Mills equations
Authors: Bartnik Robert , Fisher Mark , Oliynyk Todd A.
Published: April 2010

Globally regular (i.e., asymptotically flat and regular interior) spherically symmetric and localized (“particlelike”) solutions of the coupled Einstein Yang–Mills (EYM) equations with gauge group SU(2) have been known for more than 20 years, yet their properties are still not well understood. Spherically symmetric Yang–Mills fields are classified by a choice of isotropy generator and SO(5) is distinguished as the simplest gauge group having a model with a non-Abelian residual (little) group, SU(2)×U(1), which admits globally regular particlelike solutions. We exhibit an algebraic gauge condition which normalizes the residual gauge freedom to a finite number of discrete symmetries. This generalizes the well-known reduction to the real magnetic potential w(r,t) in the original SU(2) YM model. Reformulating using gauge-invariant polynomials dramatically simplifies the system and makes numerical search techniques feasible. We find three families of embedded SU(2) EYM equations within the SO(5) system, one of which was first detected only within the gauge-invariant polynomial reduced system. Numerical solutions representing mixtures of the three SU(2) subsystems are found, classified by a pair of positive integers.
Structural and optoelectronical characterization of Si–SiO2/SiO2 multilayers with applications in all Si tandem solar cells
Authors: Maestre D. , Palais O. , Barakel D. , Pasquinelli M. , Alfonso C. , Gourbilleau F. , De Laurentis M. , Irace A.
Published: April 2010

SiO 2 multilayers with embedded Si nanocrystals (Si-ncs) were investigated as an approach for developing highly efficient all Si tandem solar cells. The nanostructured samples, fabricated by means of a reactive magnetron sputtering, were structurally and optoelectronically characterized using different techniques. High resolution transmission electron microscopy (TEM) and energy filtered images in TEM show a high density of Si-nc with uniform sizes below 4 nm, while electrical characterization indicates high resistance values (102 kΩ) of these samples. In order to develop a better understanding of the optoelectronical behavior, photocurrent I-V curves were measured, obtaining variations under “dark” or “illumination” conditions. Recombination lifetimes in the order of tenths of nanoseconds were estimated by applying the transverse pump/probe technique.
Morphologies, structures, and interfacial electronic structure of perylene on Au(111)
Authors: Manandhar K. , Sambur J. B. , Parkinson B. A.
Published: April 2010

Various coverages of perylene thin films on Au(111) were investigated using scanning tunneling microscopy (STM) and ultraviolet photoelectron spectroscopy and x-ray photoelectron spectroscopy. A Schottky junction formed between Au(111) and perylene consisted of a large 0.65 eV interface dipole and a hole barrier height of 0.85 eV. A wetting layer of approximately 4 Å thickness was initially formed followed by island formation, consistent with Stranski–Krastanov growth. Room temperature STM investigations of nominal one monolayer perylene films revealed symmetry equivalent domains and two different stable commensurate lattice structures. Perylene film growth mode, film structure and the energy level diagram are discussed.
Influence of hole geometry and lattice constant on extraordinary optical transmission through subwavelength hole arrays in metal films
Authors: Li Jiang-Yan , Hua Yi-Lei , Fu Jin-Xin , Li Zhi-Yuan
Published: April 2010

We fabricate a series of square-lattice subwavelength circular, rectangular, and trapezoidal air-hole arrays drilled in opaque gold thin films and measured the transmission spectra of light passing through these metallic nanostructures in the near-infrared range. The measured results show strong dependence of extraordinary optical transmission on the lattice constant, hole size, and hole shape. The wavelengths of the transmission peaks and dips are mainly determined by the lattice constant. However, they are also influenced by the parameters of the hole size and hole shape. The experimental data agree well with numerical calculation results by means of a plane-wave transfer-matrix method when the detailed geometry of the air holes is fully considered. The results indicate that the extraordinary light transmission through subwavelength metallic nanostructures of air-hole arrays are governed by excitation of surface plasmon polaritons on the metal surface and their scattering by periodic air-hole arrays.
On certain new integrable second order nonlinear differential equations and their connection with two dimensional Lotka–Volterra system
Authors: Pradeep R. Gladwin , Chandrasekar V. K. , Senthilvelan M. , Lakshmanan M.
Published: April 2010

In this paper, we consider a second order nonlinear ordinary differential equation of the form ẍ+k1(ẋ2/x)+(k2+k3x)ẋ+k4x3+k5x2+k6x=0, where ki’s, i=1,2,…,6, are arbitrary parameters. By using the modified Prelle–Singer procedure, we identify five new integrable cases in this equation besides two known integrable cases, namely (i) k2=0, k3=0 and (ii) k1=0, k2=0, k5=0. Among these five, four equations admit time-dependent first integrals and the remaining one admits time-independent first integral. From the time-independent first integral, nonstandard Hamiltonian structure is deduced, thereby proving the Liouville sense of integrability. In the case of time-dependent integrals, we either explicitly integrate the system or transform to a time-independent case and deduce the underlying Hamiltonian structure. We also demonstrate that the above second order ordinary differential equation is intimately related to the two dimensional Lotka–Volterra system. From the integrable parametric choices of the above nonlinear equation all the known integrable cases of the LV system can be deduced.
Intrinsic effect of Mn doping in PZN–12%PT single crystals
Authors: Hentati Mouhamed Amin , Guennou Mael , Dammak Hichem , Khemakhem Hamadi , Thi Mai Pham
Published: April 2010

In this work we study the influence of manganese doping on the electromechanical properties of PZN–12%PT single crystal. The full electromechanical tensor of doped PZN–12%PT in the tetragonal single domain state is determined by the resonance-antiresonance method. Doping leads to a decrease in the dielectric transverse permittivity ε11T and of the shear piezoelectric coefficient d15. We show by dielectric constant ε33T measurements that the single domain state in doped crystal is stable in plates as thin as 90 μm, whereas it was unstable in plates thinner than 300 μm for the undoped crystals. This intrinsic effect is discussed by using a volume effect model based on the symmetry conforming principle of point defects. [Ren, Nature Mater. 3, 91 (2004)]. Mn doping forces the stability of PZN–12%PT single domain state, which makes the doped crystal a most suitable candidate than the pure crystal for high frequency ultrasonic medical imaging probe.
2
n
-SEMA
-a robust solid state nuclear magnetic resonance experiment for measuring heteronuclear dipolar couplings in static oriented systems using effective transverse spin-lock
Authors: Jayanthi S. , Ramanathan K. V.
Published: April 2010

Separated local field (SLF) spectroscopy is a powerful technique to measure heteronuclear dipolar couplings. The method provides site-specific dipolar couplings for oriented samples such as membrane proteins oriented in lipid bilayers and liquid crystals. A majority of the SLF techniques utilize the well-known Polarization Inversion Spin Exchange at Magic Angle (PISEMA) pulse scheme which employs spin exchange at the magic angle under Hartmann–Hahn match. Though PISEMA provides a relatively large scaling factor for the heteronuclear dipolar coupling and a better resolution along the dipolar dimension, it has a few shortcomings. One of the major problems with PISEMA is that the sequence is very much sensitive to proton carrier offset and the measured dipolar coupling changes dramatically with the change in the carrier frequency. The study presented here focuses on modified PISEMA sequences which are relatively insensitive to proton offsets over a large range. In the proposed sequences, the proton magnetization is cycled through two quadrants while the effective field is cycled through either two or four quadrants. The modified sequences have been named as 2n-SEMA where n represents the number of quadrants the effective field is cycled through. Experiments carried out on a liquid crystal and a single crystal of a model peptide demonstrate the usefulness of the modified sequences. A systematic study under various offsets and Hartmann–Hahn mismatch conditions has been carried out and the performance is compared with PISEMA under similar conditions.
Conditionally exactly solvable potentials and exceptional orthogonal polynomials
Authors: Dutta D. , Roy P.
Published: April 2010

It is shown that polynomials associated with solutions of certain conditionally exactly solvable potentials obtained via unbroken as well as broken supersymmetry belong to the category of exceptional orthogonal polynomials. Some properties of such polynomials, e.g., recurrence relation, ladder operators, differential equations, etc., have been obtained.
Comment on “Wave functions for a Duffin–Kemmer–Petiau particle in a time-dependent potential” [J. Math. Phys. 48, 073515 (2007)]
Authors: Castro L. B. , de Castro A. S.
Published: April 2010

It is shown that the paper “Wave functions for a Duffin–Kemmer–Petiau particle in a time-dependent potential” by Merad and Bensaid [J. Math. Phys. 48, 073515 (2007)] is not correct in using inadvertently a non-Hermitian Hamiltonian in a formalism that does require Hermitian Hamiltonians.
The Liouville equation for singular ergodic magnetic Schrödinger operators
Authors: Kang Yang , Klein Abel
Published: April 2010

We study the time evolution of a density matrix in a quantum mechanical system described by an ergodic magnetic Schrödinger operator with singular magnetic and electric potentials, the electric field being introduced adiabatically. We construct a unitary propagator that solves weakly the corresponding time-dependent Schrödinger equation and solve a Liouville equation in an appropriate Hilbert space.
Colossal magnetoresistance accompanied with magnetorelaxor behavior in phase-separated Ca1−xCexMnO3 thin films and CaMnO3/Ca0.92Ce0.08MnO3 superlattices
Authors: Xiang P.-H. , Yamada H. , Sawa A. , Akoh H.
Published: April 2010

We report on the transport properties of electron-doped manganite Ca1−xCexMnO3 (CCMO, 0≤x≤0.08) films and superlattices composed of insulating layers CaMnO3 (CMO) and Ca0.92Ce0.08MnO3 (CCMO8), deposited on nearly lattice-matched NdAlO3 substrates. The CCMO (x=0.06 and 0.07) films show colossal magnetoresistance (CMR) accompanied with magnetorelaxor behavior, which can be ascribed to the phase separation of canted G-type antiferromagnetic metal and C-type antiferromagnetic insulator. The (CMO)m/(CCMO8)n superlattices with 4≤m, n≤8 (unit cells) resemble the solid-solution CCMO (x=0.06 and 0.07) films in CMR and magnetorelaxor behavior, suggesting that the phase separation takes place in the superlattices. The CMR and magnetorelaxor behavior of the (CMO)m/(CCMO8)n superlattices strongly depend on the thicknesses of constituent CMO and CCMO8 layers. The origin of the phase separation in the superlattices is discussed in terms of the charge transfer and the phase competition at the interfaces.
Frequency dependent capacitance spectroscopy using conductive diamond tips on GaAs/Al2O3 junctions
Authors: Eckhardt C. , Silvano de Sousa J. , Brezna W. , Bethge O. , Bertagnolli E. , Smoliner J.
Published: April 2010

In this work, an unusual low frequency behavior observed in scanning capacitance microscopy/spectroscopy on GaAs/Al2O3 junctions is investigated. Using a two-dimensional simulation, we show that the frequency behavior of the capacitance—voltage curves can be explained through an increased minority carrier concentration at to the GaAs–Al2O3 interface and tip geometry effects on the nanoscale. An analytic approach to estimate the transition frequency between the low frequency and high frequency regime is also given.
Intertwining relations and Darboux transformations for Schrödinger equations in (n+1) dimensions
Authors: Schulze-Halberg Axel
Published: April 2010

We evaluate the intertwining relation for Schrödinger equations in (n+1) dimensions. The conditions for the existence of a Darboux transformation are analyzed and compared to their (1+1) dimensional counterparts. A complete solution of the conditions is given for (2+1) dimensions, and a Darboux transformation is constructed.
An integrable coupling family of the Toda lattice systems, its bi-Hamiltonian structure, and a related nonisospectral integrable lattice family
Authors: Xu Xi-Xiang
Published: April 2010

Starting from a four-by-four matrix spectral problem, an integrable coupling family of the Toda lattice systems is derived. A pair of discrete Hamiltonian operators is presented, and a sequence of the corresponding Hamiltonian functionals is constructed by using the discrete variational identity. Then, the bi-Hamiltonian structure of the obtained integrable coupling family is established. Finally, a nonisospectral integrable lattice family associated with the obtained integrable coupling family is given through nonisospectral discrete zero curvature representation.
Effects of rf magnetic field and wave reflection on multipactor discharge on a dielectric
Authors: Sazontov A. G. , Nevchaev V. E.
Published: April 2010

This paper analyzes the effects of the rf magnetic field and partial reflection of the circularly polarized electromagnetic wave on multipactor discharge on a dielectric. A statistical theory (taking into account the velocity spread of injected electrons) is constructed to evaluate the multipactor induced breakdown and saturation level. It is concluded that the spread of initial velocities considerably changes the condition for multipactor initiation in comparison with the dynamic approach. This effect is especially strong for the case of relatively low rf electric field amplitude (when the transit time essentially exceeds the rf period) and leads to the oscillation suppression of effective electron yield and to an increase in the threshold of multipactor growth. It is established that the rf magnetic field eliminates the upper boundary of the susceptibility diagram, while the low boundary almost remains unchanged. It is also found that the presence of partial reflection causes degradation of the saturation level (in comparison with the nonreflecting case) and results in decreasing of the characteristic time required to achieve the steady state.
Strain distribution in quantum dot of arbitrary polyhedral shape: Analytical solution
Authors: Nenashev A. V. , Dvurechenskii A. V.
Published: April 2010

An analytical expression of the strain distribution due to lattice mismatch is obtained in an infinite isotropic elastic medium (a matrix) with a three-dimensional polyhedron-shaped inclusion (a quantum dot). The expression was obtained utilizing the analogy between electrostatic and elastic theory problems. The main idea lies in similarity of behavior of point charge electric field and the strain field induced by point inclusion in the matrix. This opens a way to simplify the structure of the expression for the strain tensor. In the solution, the strain distribution consists of contributions related to faces and edges of the inclusion. A contribution of each face is proportional to the solid angle at which the face is seen from the point where the strain is calculated. A contribution of an edge is proportional to the electrostatic potential which would be induced by this edge if it is charged with a constant linear charge density. The solution is valid for the case of inclusion having the same elastic constants as the matrix. Our method can be applied also to the case of semi-infinite matrix with a free surface. Three particular cases of the general solution are considered—for inclusions of pyramidal, truncated pyramidal, and “hut-cluster” shape. In these cases considerable simplification was achieved in comparison with previously published solutions.
Deconvolution of spectral data using a doorway-coupling model Hamiltonian
Authors: Bittinger Kyle L. , Field Robert W.
Published: April 2010

The doorway-mediated mechanism for dynamical processes represents the first step beyond statistical dynamics toward an explicit mechanism. A bright state→doorway state→dark bath doorway-coupling model Hamiltonian characterizes the small molecule limit behavior of the doorway state in mediating the interaction with other dark states in the large molecule limit. Established methods of spectral deconvolution are extended to determine the parameters of a doorway-coupling model Hamiltonian from the energies and intensities of eigenstates in a high-resolution spectrum. The most important parameters of the Hamiltonian, including the doorway state energy and bright∼doorway matrix element, may be computed directly from moments of the spectral intensity distribution. We demonstrate that these parameters can be recovered accurately even when some eigenstates are unresolved. The deconvolution procedure is applied to the spectrum of the 3ν3 Ka=1 vibrational level of S1 acetylene, where a single, local, T3 doorway level mediates coupling to the T1,2 manifold. Previous studies of this S1∼T3 perturbation are discussed in light of the doorway state energies and matrix elements obtained by inversion of the spectral data.
Wavefront-sensor-based electron density measurements for laser-plasma accelerators
Authors: Plateau G. R. , Matlis N. H. , Geddes C. G. R. , Gonsalves A. J. , Shiraishi S. , Lin C. , van Mourik R. A. , Leemans W. P.
Published: April 2010

Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength and hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, offer greater phase sensitivity and straightforward analysis, improving shot-to-shot plasma density diagnostics.
Note: Thermal analog to atomic force microscopy force-displacement measurements for nanoscale interfacial contact resistance
Authors: Iverson Brian D. , Blendell John E. , Garimella Suresh V.
Published: April 2010

Thermal diffusion measurements on polymethylmethacrylate-coated Si substrates using heated atomic force microscopy tips were performed to determine the contact resistance between an organic thin film and Si. The measurement methodology presented demonstrates how the thermal contrast signal obtained during a force-displacement ramp is used to quantify the resistance to heat transfer through an internal interface. The results also delineate the interrogation thickness beyond which thermal diffusion in the organic thin film is not affected appreciably by the underlying substrate.
Simulation of striation in large-gap coplanar plasma display panels
Authors: He Feng , Zhao Xiaofei , He Shoujie , Ouyang Jiting
Published: April 2010

The discharge processes and striation phenomenon in large-gap coplanar plasma display panels (PDPs) were investigated by particle-in-cell/Monte Carlo collision. The current pulse on electrodes and the delay time of discharge in simulation are consistent with the experimental results in large-gap PDP cell. Moreover, the current on cathode is mainly by displacement current during the rising edge of the second discharge. The evolution of the second series striations shows that the change in potential causes the striations “suddenly” change from the first series to the second one. The spatial distribution of electron energy and electron energy distribution function (EEDF) are also obtained in the simulation. In the region of striation, the average energy of electrons changes remarkably as the striation forms, and EEDF is similar to that in the negative glow region. Negative glow can be considered as the important region in striation forming.
Island-to-percolation transition during the room-temperature growth of sputtered nanoscale Pd films on hexagonal SiC
Authors: Ruffino F. , Grimaldi M. G.
Published: April 2010

We have studied the growth of room-temperature sputtered Pd films on 6H-SiC by using the atomic force microscopy technique. In particular, we analyzed the Pd film surface morphology as a function of the film thickness from 3 to 72 nm observing that the Pd grows initially (thickness 2–12 nm) as three-dimensional (3D) islands. Then (thickness 12–36 nm) the Pd film morphology evolves from compact 3D islands to partially coalesced wormlike structures, followed (36–60 nm) by a percolation morphology and finally to a continuous and rough film (at 72 nm). The application of the interrupted coalescence model allowed us to evaluate the critical mean islands diameter Rc≈6.6 nm for the partial coalescence process while the application of the kinetic freezing model allowed us to evaluate the room-temperature Pd surface diffusion coefficient Ds≈1.4×10−17 m2/s on 6H-SiC. Finally, the application of the Vincent’s model allowed us to evaluate the critical Pd coverage Pc=68% for the percolation transition.
Optical properties of quasi-tetragonal BiFeO3 thin films
Authors: Chen P. , Podraza N. J. , Xu X. S. , Melville A. , Vlahos E. , Gopalan V. , Ramesh R. , Schlom D. G. , Musfeldt J. L.
Published: April 2010

Optical transmission spectroscopy and spectroscopic ellipsometry were used to extract the optical properties of an epitaxially grown quasi-tetragonal BiFeO3 thin film in the near infrared to near ultraviolet range. The absorption spectrum is overall blue shifted compared with that of rhombohedral BiFeO3, with an absorption onset near 2.25 eV, a direct 3.1 eV band gap, and charge transfer excitations that are ∼0.4 eV higher than those of the rhombohedral counterpart. We interpret these results in terms of structural strain and local symmetry breaking.
Dynamics of chains and dendrimers with heterogeneous semiflexibility
Authors: Dolgushev Maxim , Blumen Alexander
Published: April 2010

Based on our recent model for the dynamics of semiflexlible treelike networks [M. Dolgushev and A. Blumen, J. Chem. Phys. 131, 044905 (2009)], we study the dynamical properties of chain polymers and of dendrimers whose junctions display different stiffness degrees (SD). In these polymers the functionality f of the inner junctions is constant, being f=2 for the linear chains and f=3 for the dendrimers. This allows us to focus on the effects caused by the heterogeneities due to different SD. For this we study alternating, diblock, as well as random arrangements of the SD. Each of these cases shows a particular, macroscopically observable behavior, which allows to distinguish between the different microscopic SD arrangements.
Finite temperature infrared spectroscopy of polycyclic aromatic hydrocarbon molecules: Path-integral molecular dynamics
Authors: Calvo F. , Parneix P. , Van-Oanh N.-T.
Published: April 2010

The vibrational spectra of the naphthalene, pyrene, and coronene molecules have been computed in the 0–3500 cm−1 infrared range using classical and quantum molecular dynamics simulations based on a dedicated tight-binding potential energy surface. The ring-polymer molecular dynamics (RPMD) and partially adiabatic centroid molecular dynamics (CMD) methods have been employed to account for quantum nuclear effects. The contributions of quantum delocalization to the line shift and broadening are significant in the entire spectral range and of comparable magnitude as pure thermal effects. While the two methods generally produce similar results, the CMD method may converge slower at low temperature with increasing Trotter discretization number. However, and contrary to the CMD method, the RPMD approach suffers from serious resonance problems at high frequencies and low temperatures.
Strong field effects in rotational femtosecond degenerate four-wave mixing
Authors: Gelin Maxim F. , Riehn Christoph , Kunitski Maksim , Brutschy Bernhard
Published: April 2010

We study theoretically strong field effects in rotational femtosecond degenerate four-wave-mixing (DFWM). First, we developed a perturbative approach and calculated the leading correction to the standard (weak field) formula for femtosecond DFWM signal. Second, we constructed a nonperturbative approach for computing femtosecond DFWM signals excited by (short) pulses of arbitrary intensity. Third, we worked out the theory to describe femtosecond DFWM with an extra aligning pulse. We show that the strong-pulse-induced nonadiabatic alignment does explain many experimentally detected features that develop in femtosecond DFWM signals with increasing laser intensity beyond the standard weak field regime. However, we also show that this nonadiabatic alignment cannot solely be responsible for the onset of the heterodyne detection and pronounced constant background in DFWM signals excited by high intensity laser pulses.
The inverse problem for the Gross–Pitaevskii equation
Authors: Malomed Boris A. , Stepanyants Yury A.
Published: April 2010

Two different methods are proposed for the generation of wide classes of exact solutions to the stationary Gross–Pitaevskii equation (GPE). The first method, suggested by the work of Kondrat’ev and Miller [Izv. Vyssh. Uchebn. Zaved., Radiofiz IX, 910 (1966)], applies to one-dimensional (1D) GPE. It is based on the similarity between the GPE and the integrable Gardner equation, all solutions of the latter equation (both stationary and nonstationary ones) generating exact solutions to the GPE. The second method is based on the “inverse problem” for the GPE, i.e., construction of a potential function which provides a desirable solution to the equation. Systematic results are presented for one- and two-dimensional cases. Both methods are illustrated by a variety of localized solutions, including solitary vortices, for both attractive and repulsive nonlinearity in the GPE. The stability of the 1D solutions is tested by direct simulations of the time-dependent GPE.
Fluorescent resonant excitation energy transfer in linear polyenes
Authors: Das Mousumi , Ramasesha S.
Published: April 2010

We have studied the dynamics of excitation transfer between two conjugated polyene molecules whose intermolecular separation is comparable to the molecular dimensions. We have employed a correlated electron model that includes both the charge-charge, charge-bond, and bond-bond intermolecular electron repulsion integrals. We have shown that the excitation transfer rate varies as inverse square of donor-acceptor separation R−2 rather than as R−6, suggested by the Förster type of dipolar approximation. Our time-evolution study also shows that the orientational dependence on excitation transfer at a fixed short donor-acceptor separation cannot be explained by Förster type of dipolar approximation beyond a certain orientational angle of rotation of an acceptor polyene with respect to the donor polyene. The actual excitation transfer rate beyond a certain orientational angle is faster than the Förster type of dipolar approximation rate. We have also studied the excitation transfer process in a pair of push-pull polyenes for different push-pull strengths. We have seen that, depending on the push-pull strength, excitation transfer could occur to other dipole coupled states. Our study also allows for the excitation energy transfer to optically dark states which are excluded by Förster theory since the one-photon transition intensity to these states (from the ground state) is zero.
New laser apparatus to measure oscillation amplitude down to picometer at megahertz frequencies
Authors: Zhang F. Z. , Walheim S. , Schimmel T. , Marti O.
Published: April 2010

A laser setup to study shear oscillations at small amplitudes with resonance frequencies up to 3 MHz is presented. The new approach combines gauging of the Gaussian laser beam and a lock-in amplifier. The device is tested with a 3 MHz AT-cut quartz crystal. The oscillation amplitude at the edge of the electrode on the quartz crystal is measured with a resolution of 2 pm.