bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuro-otological findings in tinnitus patients with normal hearing
Authors: Morales-Garcia C , Quiroz G , Matamala J M , Tapia C
Published: December 2009

Introduction:

Tinnitus is usually associated with hearing loss, and patients with tinnitus and normal hearing are unusual. Neuro-otological findings have not previously been described in tinnitus patients with normal hearing.

Aim:

To analyse neuro-otological examination results from a group of tinnitus patients with normal hearing.

Materials and methods:

Seventeen normal-hearing tinnitus patients seen over a 10-year period were retrospectively evaluated. Their results were compared with those of a control group of 17 normal subjects without tinnitus.

Results:

The main neuro-otological finding in the tinnitus patients was caloric test abnormality: a unilateral canal paresis was present in 15 of the 17 patients. Caloric tests were normal in 15 of the 17 control subjects.

Conclusion:

We may infer from these results that tinnitus could be the only clinical manifestation of a cochlear – and presumably cochleo-vestibular – lesion, and that unilateral canal paresis may be the only abnormal finding on neuro-otological examination.
Closed rhinoplasty approach for excision of nasal dermoids
Authors: Harris R L , Daya H
Published: December 2009

Objective:

To assess the efficacy of excision of nasal dermoids through a closed rhinoplasty incision. This is the first description of the use of this approach for excision of superficial nasal dermoids.

Methods:

Three boys aged five, nine and 12 years presented with midline nasal dermoids with minimal cutaneous involvement. Magnetic resonance imaging demonstrated distinct, cystic, superficial nasal masses. The cysts were excised through a closed rhinoplasty approach. In each case, completeness of extirpation was judged by histopathological examination of the excised specimen. Aesthetic outcome was recorded photographically.

Results:

All three patients' cysts were completely excised, with excellent cosmetic results.

Conclusions:

The closed rhinoplasty incision is another approach in the surgeon's armamentarium for excision of small, superficial nasal dermoid cysts. In well selected cases, this approach gives optimal cosmetic results, provides adequate exposure with minimal dissection, and allows total extirpation.
Self-limiting benign paroxysmal positional vertigo following use of whole-body vibration training plate
Authors: Amir I , Young E , Belloso A
Published: December 2009

Objective:

We describe a case of benign paroxysmal positional vertigo which occurred after use of a whole-body vibration training plate.

Method:

Case report and literature review concerning the secondary causes of benign paroxysmal positional vertigo and the physiological effects of whole-body vibration training plates.

Results:

A 44-year-old woman was referred with classic symptoms of benign paroxysmal positional vertigo following use of a whole-body vibration training plate, a popular form of fitness equipment widely used in sports, rehabilitation and beauty treatments. The condition resolved spontaneously after several days. There have been reports of negative side effects in users of this equipment, such as dizziness, headache and a sensation of imbalance; however, there have been no reported cases involving vertigo. Based on a literature review, this equipment may cause side effects, including vertigo, by generating forces that can increase the original amplitude of internal organs, which may potentially cause labyrinthine trauma or dislocation of otoconia, leading to benign paroxysmal positional vertigo.

Conclusions:

We suggest that whole-body vibration training plates may potentially induce benign paroxysmal positional vertigo. Manufacturers may need to make users of this equipment aware of this risk, and remind them to use it with caution.
Rank-one ℤdactions and directional entropy
Authors: ARTHUR ROBINSON E. , ŞAHİN AYŞE A.
Published: December 2009

We study the dynamic properties of rank-one ℤdactions as a function of the geometry of the shapes of the towers generating the action. Some basic properties require only minimal restrictions on the geometry of the towers. Our main results concern the directional entropy of rank-one ℤdactions with rectangular tower shapes, where we show that the geometry of the rectangles plays a significant role. We show that for eachn≤dthere is ann-dimensional direction with entropy zero. We also show that if the growth in eccentricity of the rectangular towers is sub-exponential, then all directional entropies are zero. An example of D. Rudolph shows that, without a restriction on eccentricity, a positive entropy direction is possible.
The concept of ‘ageing well’ in ten Latin American and European countries
Authors: FERNÁNDEZ-BALLESTEROS R. , GARCIA L F. , ABARCA D. , BLANC E. , EFKLIDES A. , MORAITOU D. , KORNFELD R. , LERMA A. J. , MENDOZA-NUMEZ V. M. , MENDOZA-RUVALCABA N. M. , OROSA T. , PAUL C. , PATRICIA S.
Published: December 2009

A review of several studies examining the lay concept of successful ageing and related concepts leads to the conclusion that elders from different cultures appear to agree on most of the components identified in the literature. From the research emerges a multidimensional conceptualisation of ‘successful ageing’ that is described on the basis of physical, emotional, cognitive and social domains, and which coincides with most theoretical and empirical definitions. The main goal of the present research is to study similarities and differences between concepts of ‘successful ageing’ in several Latin American and European countries and in two different age groups, and also to examine whether a similar structure of the lay concept can be found across both continents. The results show minor differences at item levels among countries, continents and age groups, and a similar internal structure across them.
Throttle and brake pedals automation for populated areas
Authors: Onieva E. , Milanés V. , González C. , de Pedro T. , Pérez J. , Alonso J.
Published: December 2009

Artificial intelligence techniques applied to control processes are particularly useful when the elements to be controlled are complex and can not be described by a linear model. A trade-off between performance and complexity is the main factor in the design of this kind of system. The use of fuzzy logic is specially indicated when trying to emulate such human control actions as driving a car. This paper presents a fuzzy system that cooperatively controls the throttle and brake pedals for automatic speed control up to 50km/h. It is thus appropriate for populated areas where driving involves constant speed changes, but within a range of low speeds because of traffic jams, road signs, traffic lights, etc. The system gets the current and desired speeds for the car and generates outputs to control the two pedals. It has been implemented in a real car, and tested in real road conditions, showing good speed control with smooth actions resulting in accelerations that are comfortable for the car's occupants.
Successive single-word utterances and use of conversational input: a pre-syntactic route to multiword utterances
Authors: HERR-ISRAEL ELLEN , McCUNE LORRAINE
Published: December 2009

In the period between sole use of single words and majority use of multiword utterances, children draw from their existing productive capability and conversational input to facilitate the eventual outcome of majority use of multiword utterances. During this period, children use word combinations that are not yet mature multiword utterances, termed ‘successive single-word utterances’ (SSWUs). The language development of five children, observed in play with their mothers, was studied longitudinally across the transitional period (age 1 ; 3 to 2 ; 0). Results demonstrate a common developmental trajectory from single words to SSWUs, formed with the support of conversation, to more independent SSWUs, and finally to majority use of multiword utterances. The children varied in the extent to which they produced SSWUs and whether they first produced across-turn versus within-turn SSWUs. Possible reasons for variability and why SSWU production may be important to the development of multiword utterances are discussed.
Nesting success of a managed population of Mauritius Fodies Foudia rubra marooned on a partially restored island
Authors: CRISTINACCE ANDREW , GARRETT LUCY J. H. , COLE RUTH E. , TATAYAH R. V. VIKASH , JONES CARL G.
Published: December 2009

The marooning of populations on offshore islands can be used as a conservation technique for species threatened by introduced predators, but post-release breeding success is not always as high as expected. Following the release of Mauritius Fodies onto a partially restored islet of regenerating forest, supplementary food and control of nest parasites through the application of insecticide were used as precautionary measures to aid the establishment of a population. Nests were continuously monitored in the first three breeding seasons to inform future management decisions. The fodies built nests in taller, more mature vegetation and younger females were more likely to abandon nests before incubation started. Eggs were laid between July and February and nests made earlier in the season were more likely to fledge young. Treating nests with the insecticide carbaryl increased the probability of success, but the distance of the nest from the supplementary feeding aviaries had no effect. The number of young per female decreased each breeding season and nesting success was similar to that of fodies using exotic plantation trees on the mainland between 2002 and 2006. Future research using population models and adaptive management could lead to the withdrawal or reduction of support measures for the released population and/or the harvest of individuals to establish populations on other offshore islands.
Threats of environmental mercury to birds: knowledge gaps and priorities for future research
Authors: SEEWAGEN CHAD L.
Published: December 2009

Anthropogenic emissions of mercury have doubled over the past two centuries. Mercury is a dangerous neurotoxin that threatens human health and fish and wildlife populations. The effects of mercury on birds have been relatively well-studied in the laboratory and in nature. Several aspects of neurology, physiology, behaviour, and reproduction have been shown to be adversely affected. Many studies have documented ataxia, lethargy, reduced appetite, reduced egg production, poor hatching success, and aberrant parental care in birds exposed to mercury.

The majority of the research done to date, however, has been focused on select taxa (waterbirds), trophic levels (piscivores), habitat types (aquatic systems), geographic regions (North America and Europe), and life history stages (reproduction), leaving the assessment of mercury's threats to birds incomplete. Successful bird conservation strategies are dependent on a comprehensive understanding of the threats facing populations. Here, I discuss the significant knowledge gaps that remain and subsequently suggest priorities for future mercury research in birds. Studies of mercury in terrestrial, insectivorous, and/or passerine species, and how mercury affects migration are especially recommended to fill gaps in our present understanding.
Neuropsychological outcomes after coronary artery bypass grafting
Authors: SELNES OLA A. , GOTTESMAN REBECCA F.
Published: December 2009

Short- and long-term cognitive declines after cardiac surgery with cardiopulmonary bypass have been reported, but the frequency, severity, nature, and etiology of postoperative cognitive changes have been difficult to quantify. Current studies have corrected the principal methodological shortcoming of earlier studies by including control groups, and have shown that while early postoperative cognitive decline does occur in some patients, it is generally mild and reversible by 3 months after surgery. Late cognitive changes do occur, but comparison with patients undergoing off-pump surgery or those being treated medically suggests that these changes are not specific to CABG or more specifically to the use of cardiopulmonary bypass. (JINS, 2010, 16, 221–226.)
Trente-sixième circulaire à Messieurs les Présidents et let Membres des Comités centraux de secours aux militaires blessés
Authors: Ador G. , Micheli L.
Published: December 2009

Nous avons l'honneur de porter à la connaissance des Comités centraux, qu'une Société ottomane de secours aux blessés et malades militaires vient de se constituer à Constantinople, sur les bases du Congrès international de Genève, ainsi que nous l'apprend une circulaire de S. E. Marco-Pacha, président de la Commission d'organisation.
Circulaire de la société Ottomane
Authors: Pacha Docteur Marco
Published: December 2009

La Société, fondée sur les bases du Congrès internatíonal de Genève, a pour but de venir en aide, par des ambulances libres, aux ambulances militaires et d'apporter au soulagement des blessés toutes les ressources de la science et de la charité.

La Convention de Genève a stipulé la neutralité des ambulances et de leur personnel.
Comité central
Authors: Maggiorani V. , Vitelleschi Marquis Francesco Nobili
Published: December 2009

J'ai l'honneur de vous annoncer que, le 21 décembre dernier, comme le prescrit l'article transitoire no 3, le Comité central s'est réuni pour élire le Conseil directeur, en vertu de l'article 13 des statuts.

Le Conseil directeur reste composé de la manière suivante:

Président: le Commandeur Enrico Guicciardi, sénateur.
L'eclairage sur le champ de bataille pour la recherche des blessés
Authors: Dr Ferrière
Published: December 2009

M. Jacob, médecin-major de première classe, professeur agrégé au Val-de- Grâce s'est livré récemment à des études comparatives sur les différents modes d'éclairage pour la recherche des blessés sur le champ de bataille. Les essais ont porté soit sur des appareils transportables par voitures spéciales, en particulier sur le projecteur électrique de Gaiffe à lampe de 40 ampères, soit sur des appareils transportables par petits chariots ou par deux hommes, en particulier le « Fulgur » et « l'Alpha », soit enfin sur des appareils transportables par un seul homme, spécialement le phare à acétylène de Blériot et l'appareil à lumière oxhydrique ou oxyéthérique de Radiguet.
Constitution physiologique des compagnies
Authors: Dr Ferrière
Published: December 2009

Sons la signature de M. le Dr Bonnette, médecin-major de 2meclasse de l'armée française, nous lisons, dans leCaducéedu 17 août dernier, l'intéressant article qui suit sur la question de la répartition des secours par rang de robusticité physique.
Présidence du Comité central
Authors: de Véliaminoff Zernoff S.
Published: December 2009

Le Comité central de la Société russe de la Croix-Rouge a l'honneur de porter à votre connaissance que, dans sa séance du 7/20 juin 1907, M. le prince M. I. Hilkoff, conseiller privé actuel, secrétaire d'Etat de Sa Majesté l'Empereur et membre du Conseil de l'Empire, a été élu président de la Croix-Rouge de Russie.
Accession à la Convention de Genève de 1906
Authors: Brenner
Published: December 2009

Par note du 24 août dont ci-joint copie, le Gouvernement Impérial ottoman a porté à notre connaissance qu'il adhère à la convention pour l'amélioration du sort des blessés et malades dans les armées en campagne, conclue à Genève le 6 juillet 1906, sous la réserve qu'il se servira dans ses armées de l'emblème du croissant rouge pour protéger ses ambulances.
Regional forest growth rates measured by combining ICESat GLAS and Landsat data
Authors: Dolan Katelyn , Masek Jeffrey G. , Huang Chengquan , Sun Guoqing
Published: December 2009

Forest canopy heights derived from ICESat Geoscience Laser Altimeter System (GLAS) lidar data were combined with Landsat‐based disturbance history maps to assess forest regeneration rates in three regions of the eastern United States (Maine, Virginia, and Mississippi). GLAS observations were screened for topographic relief and waveform quality, and canopy heights were obtained by visual inspection of each waveform. Regressing the GLAS heights against the age of last disturbance yielded vertical growth rates of 0.6 m/yr (Maine), 1.0 m/yr (Virginia), and 1.2 m/yr (Mississippi). Growth rates, when combined with height‐biomass allometric relations, can be converted to estimates of aboveground wood productivity. The study demonstrates that large‐footprint lidar data can be used to measure vertical growth rates when averaged spatially, thus providing unique information on forest regeneration for carbon cycle studies.
Deglacial diatom productivity and surface ocean properties over the Bermuda Rise, northeast Sargasso Sea
Authors: Gil Isabelle M. , Keigwin Lloyd D. , Abrantes Fatima G.
Published: December 2009

Diatom assemblages document surface hydrographic changes over the Bermuda Rise. Between 19.2 and 14.5 ka, subtropical diatom species and Chaetoceros resting spores dominate the flora, as in North Atlantic productive regions today. From 16.9 to 14.6 ka, brackish and fresh water diatoms are common and their contribution is generally coupled with total diatom abundance. This same interval also contains rare grains of ice‐rafted debris. Coupling between those proxies suggests that successive discharge of icebergs might have stimulated productivity during Heinrich event 1 (H1). Iceberg migration to the subtropics likely created an isolated environment involving turbulent mixing, upwelled water, and nutrient‐rich meltwater, supporting diatom productivity in an otherwise oligotrophic setting. In addition, the occurrence of mode water eddies likely brought silica‐rich waters of Southern Ocean origin to the euphotic zone. The persistence of lower‐salinity surface water beyond the last ice rafting suggests continued injection of fresh water by cold‐core rings and advection around the subtropical gyre. These results indicate that opal productivity may have biased estimates of meridional overturning based on 231Pa/230Th ratios in Bermuda Rise sediments during H1.
How different would tropospheric oxidation be over an ice‐free Arctic?
Authors: Voulgarakis A. , Yang X. , Pyle J. A.
Published: December 2009

Climate projections suggest that a complete Arctic sea‐ice retreat is likely in the future during summer. Less ice will cause less light reflection and slower tropospheric photolysis. We use a tropospheric chemistry model to examine how oxidation may differ over an ice‐free Arctic. We find that late‐summer OH concentrations can decrease by 30–60% at polar latitudes, while effects on local ozone and global oxidant abundances are small. Ozone changes become larger in the more extreme case where sea‐ice is also removed in spring and early summer. In this case, we find large spring ozone increases (up to 50–60%) over the Arctic, and even over inhabited high latitude regions (up to 20%), due mainly to a reduction in the impact of bromine chemistry, caused by the sea‐ice retreat. Annual mean ozone also increases in the run with the summer/spring sea‐ice removal, but not in the simulation including only late‐summer sea‐ice removal.
Theory and observations of Ekman flux in the chlorophyll distribution downstream of South Georgia
Authors: Venables Hugh J. , Meredith Michael P.
Published: December 2009

A large phytoplankton bloom occurs downstream of South Georgia, an island on the northern edge of the Scotia Sea, Atlantic sector of the Southern Ocean. This is due to natural iron fertilisation being advected downstream in the Antarctic Circumpolar Current. Mapping of SeaWiFS chl‐a in dynamic height/longitude space reveals the trajectory of surface water under the dual influences of geostrophic flow and Ekman flux. A theoretical estimate of the trajectory shows good agreement with observations. The trajectory is dependent on the wind stress:mixed layer depth ratio, but independent of the latitudinal separation of dynamic height contours. The chl‐a distribution suggests that iron reaches 20°W below the mixed layer, away from the effects of Ekman flux, but beyond the iron is confined to the surface layer. Chl‐a reduces monotonically east of South Georgia with the signal detectable to 15°E, over 3500 km downstream, indicating the basin‐scale biogeochemical influence of the iron supply.
Hortonian scaling and effect of cutoffs on statistics of self‐affine river networks
Authors: Neuman Shlomo P.
Published: December 2009

The planar structure of river networks exhibits fractal properties. In particular, available data indicate a tendency for drainage areas A to be distributed according to a power law; their boundaries and main channels to form self‐affine curves; the characteristic lengths of drainage areas to be independently self‐affine in the one‐dimensional space Z of total channel length, rendering the network elongated (and anisotropic); the inverse network density A/Z to be either constant or self‐affine in Z, depending on whether or not the network fills the two‐dimensional space of A; and (as found in a recent study) areas of given size, vegetative cover, and mean steady state soil moisture, weighted by their flow distance from the basin outlet, to be self‐affine in the one‐dimensional space of this distance. Various theoretical and semiempirical relationships have been proposed among exponents defining some of these and other scale dependencies. Expressions have been proposed for ensemble moments of A and some length measures associated with finite size river basins. We present a new model that views any self‐affine basin property, Y(X), as belonging to an infinite hierarchy of mutually uncorrelated, statistically homogeneous random functions defined on elementary subbasins, each of which is characterized by a unique integral (spatial correlation) scale λ. We cite a mathematically rigorous hydrologic rationale for our model and use it in conjunction with published scaling relations to obtain the probability density function of λ; to derive analytical expressions for ensemble analogs of Horton's scaling laws; to deduce from them that streams of any Horton‐Strahler order ω are associated with integral scales λω ≤ λ ≤ λω+1, where the ratio λω+1/λω is a constant independent of ω; to develop analytical expressions relating statistical moments of Y(X) to arbitrary lower and upper cutoff scales that may (but need not) be taken to represent data support and maximum watershed size; to describe ways of estimating the corresponding parameters; and to provide a theoretical basis for the heretofore unexplained observation that self‐affine amplitude fluctuations of basin boundaries and main channels (as measured by their variance), having a common Hurst exponent, are larger in the former than in the latter.
Intergenic transcripts originating from a subclass of ribosomal DNA repeats silence ribosomal RNA genes in trans
Authors: Santoro Raffaella , Schmitz Kerstin‐Maike , Sandoval Juan , Grummt Ingrid
Published: December 2009

Epigenetic silencing of a fraction of ribosomal DNA (rDNA) requires association of the nucleolar chromatin‐remodelling complex NoRC to 150–250 nucleotide RNAs (pRNA) that originate from an RNA polymerase I promoter located in the intergenic spacer separating rDNA repeats. Here, we show that NoRC‐associated pRNA is transcribed from a sub‐fraction of hypomethylated rRNA genes during mid S phase, acting in trans to inherit DNA methylation and transcriptional repression of late‐replicating silent rDNA copies. The results reveal variability between individual rDNA clusters with distinct functional consequences.
Intrauterine programming of ageing
Authors: Fernandez‐Capetillo Oscar
Published: December 2009

Ageing is an unavoidable corollary to being alive; the most intuitive interpretation of ageing being that it is the consequence of progressive body degeneration. In agreement with this, current models propose that ageing occurs through a stepwise accumulation of DNA damage, which ultimately limits the regenerative capacity of tissues. On the other hand, there is increasing evidence that fetal distress can influence the development of disease in adult life, a phenomenon known as ‘intrauterine programming’. The extent to which an intrauterine exposure to DNA damage can compromise lifespan remains unclear. My group has recently generated a murine model of a human syndrome linked to defective DNA repair and observed that these animals age prematurely, but the accumulation of DNA damage is restricted mostly to the embryonic period. Here, I discuss the implications of this finding and propose that ageing can be influenced by fetal distress.
Conduction mechanism of sputtered BaTiO3 film on Ni substrate
Authors: Bao Lijie , Ryley James , Li Zhigang , Wilker Charles , Zhang Lei , Reardon Damien , Opila Robert
Published: December 2009

BaTiO 3 (BTO) thin film capacitors were deposited on Ni substrate using rf magnetron sputtering. Microstructural studies by x-ray diffraction and transmission electron microscopy reveal that the as-grown BTO films have the columnar structure and the good interface structure. Postdeposition anneal results in the recrystallization of BTO films. The electrical measurements exhibit that the BTO films have high capacitance densities and low leakage currents.
Numerical calculations of RF efficiency from a soliton generating nonlinear transmission line
Authors: Marksteiner Q. R. , Carlsten Bruce , Russell Steve
Published: December 2009

The output frequency and RF generating efficiency of a lumped element or periodic transmission line with nonlinear capacitors and linear inductors is investigated, using both a purely resistive linear load and a load that contains linear reactive components. The nonlinear transmission line creates high frequency RF by converting a long unipolar input pulse into a train of rapidly oscillating solitons. The RF efficiency increases as the modulation depth between adjacent solitons deepens, and is affected by the nonlinearity of the line and the total number of nonlinear stages used. A linear resistive termination distorts the pulse so as to reduce the RF efficiency, particularly when the nonlinearity is high. The RF efficiency is found to increase significantly when a linear load with reactive elements is used which absorbs the desired high frequency component of the signal but reflects the remaining low frequency parts of the signal back into the line.
Photoemission electron microscopy using extreme ultraviolet attosecond pulse trains
Authors: Mikkelsen A. , Schwenke J. , Fordell T. , Luo G. , Klünder K. , Hilner E. , Anttu N. , Zakharov A. A. , Lundgren E. , Mauritsson J. , Andersen J. N. , Xu H. Q. , L’Huillier A.
Published: December 2009

We report the first experiments carried out on a new imaging setup, which combines the high spatial resolution of a photoemission electron microscope (PEEM) with the temporal resolution of extreme ultraviolet (XUV) attosecond pulse trains. The very short pulses were provided by high-harmonic generation and used to illuminate lithographic structures and Au nanoparticles, which, in turn, were imaged with a PEEM resolving features below 300 nm. We argue that the spatial resolution is limited by the lack of electron energy filtering in this particular demonstration experiment. Problems with extensive space charge effects, which can occur due to the low probe pulse repetition rate and extremely short duration, are solved by reducing peak intensity while maintaining a sufficient average intensity to allow imaging. Finally, a powerful femtosecond infrared (IR) beam was combined with the XUV beam in a pump-probe setup where delays could be varied from subfemtoseconds to picoseconds. The IR pump beam could induce multiphoton electron emission in resonant features on the surface. The interaction between the electrons emitted by the pump and probe pulses could be observed.
Multiple classical limits in relativistic and nonrelativistic quantum mechanics
Authors: Yokomizo N. , Barata J. C. A.
Published: December 2009

The existence of a classical limit describing the interacting particles in a second-quantized theory of identical particles with bosonic symmetry is proved. This limit exists in addition to the previously established classical limit with a classical field behavior, showing that the limit ℏ→0 of the theory is not unique. An analogous result is valid for a free massive scalar field: two distinct classical limits are proved to exist, describing a system of particles or a classical field. The introduction of local operators in order to represent kinematical properties of interest is shown to break the permutation symmetry under some localizability conditions, allowing the study of individual particle properties.
Density functional estimations of Heisenberg exchange constants in oligonuclear magnetic compounds: Assessment of density functional theory versus ab initio
Authors: Zein Samir , Poor Kalhor Mahboubeh , Chibotaru Liviu F. , Chermette Henry
Published: December 2009

Modern density functionals were assessed for the calculation of magnetic exchange constants of academic hydrogen oligomer systems. Full-configuration interaction magnetic exchange constants and wavefunctions are taken as references for several Hn model systems with different geometrical distributions from Ciofini et al. [Chem. Phys. 309, 133 (2005)]. Regression analyses indicate that hybrid functionals (B3LYP, O3LYP, and PBE0) rank among the best ones with a slope of typically 0.5, i.e., 100% overestimation with a standard error of about 50 cm−1. The efficiency of the highly ranked functionals for predicting the correct “exact states” (after diagonalization of the Heisenberg Hamiltonian) is validated, and a statistical standard error is assigned for each functional. The singular value decomposition approach is used for treating the overdetermination of the system of equations when the number of magnetic centers is greater than 3. Further discussions particularly about the fortuitous success of the Becke00-x-only functional for treating hydrogenic models are presented.
Lithium adsorption on zigzag graphene nanoribbons
Authors: Uthaisar Chananate , Barone Veronica , Peralta Juan E.
Published: December 2009

We have studied the adsorption of Li atoms at the hollow sites of graphene nanoribbons (zigzag and armchair), graphene, and fullerenes by means of density functional theory calculations including local and semilocal functionals. The binding energy of a Li atom on armchair nanoribbons [of about 1.70 eV for local spin density approximation (LSDA) and 1.20 eV for Perdew–Burke–Ernzerhof (PBE)] is comparable to the corresponding value in graphene (1.55 and 1.04 eV for LSDA and PBE, respectively). Notably, the interaction between Li and zigzag nanoribbons is much stronger. The binding energy of Li at the edges of zigzag nanoribbons is about 50% stronger than in graphene for the functionals studied here. While the charge transfer between the Li adatom and the zigzag nanoribbon significantly affects the magnetic properties of the latter providing an additional interaction mechanism that is not present in a two-dimensional graphene or armchair nanoribbons, we find that the morphology of the edges, rather than magnetism, is responsible for the enhanced Li-nanoribbon interaction.
MgO barrier-perpendicular magnetic tunnel junctions with CoFe/Pd multilayers and ferromagnetic insertion layers
Authors: Mizunuma K. , Ikeda S. , Park J. H. , Yamamoto H. , Gan H. , Miura K. , Hasegawa H. , Hayakawa J. , Matsukura F. , Ohno H.
Published: December 2009

The authors studied an effect of ferromagnetic (Co20Fe60B20 or Fe) layer insertion on tunnel magnetoresistance (TMR) properties of MgO-barrier magnetic tunnel junctions (MTJs) with CoFe/Pd multilayer electrodes. TMR ratio in MTJs with CoFeB/MgO/Fe stack reached 67% at annealing temperature (Ta) of 200 °C and then decreased rapidly at Ta over 250 °C. The degradation of the TMR ratio may be related to crystallization of CoFe(B) into fcc(111) or bcc(011) texture resulting from diffusion of B into Pd layers. MTJs which were in situ annealed at 350 °C just after depositing bottom CoFe/Pd multilayer showed TMR ratio of 78% by postannealing at Ta=200 °C.
Detection of percolating paths in polyhedral segregated network composites using electrostatic force microscopy and conductive atomic force microscopy
Authors: Waddell J. , Ou R. , Capozzi C. J. , Gupta S. , Parker C. A. , Gerhardt R. A. , Seal K. , Kalinin S. V. , Baddorf A. P.
Published: December 2009

Composite specimens possessing polyhedral segregated network microstructures require a very small amount of nanosize filler, <1 vol %, to reach percolation because percolation occurs by accumulation of the fillers along the edges of the deformed polymer matrix particles. In this paper, electrostatic force microscopy (EFM) and conductive atomic force microscopy (C-AFM) were used to confirm the location of the nanosize fillers and the corresponding percolating paths in polymethyl methacrylate/carbon black composites. The EFM and C-AFM images revealed that the polyhedral polymer particles were coated with filler, primarily on the edges as predicted by the geometric models provided.
A combined electro-optical method for the determination of the recombination parameters in InGaN-based light-emitting diodes
Authors: Meneghini Matteo , Trivellin Nicola , Meneghesso Gaudenzio , Zanoni Enrico , Zehnder Ulrich , Hahn Berthold
Published: December 2009

We present an electro-optical method for the extrapolation of the nonradiative and Auger recombination coefficients in InGaN/GaN Light-emitting diodes (LEDs). The method has the advantage of permitting the extrapolation of the recombination parameters of packaged devices, contrary to conventional techniques based on the analysis of quasibulk structures. For the analyzed devices, the average values of the nonradiative and Auger recombination coefficients have been determined to be equal to 2.3×107 s−1 and 1.0×10−30 cm6 s−1, respectively. These results are consistent with previous reports based on the analysis of quasibulk structures and on theoretical simulations. The method described in this paper constitutes an efficient tool for the analysis of the recombination dynamics in GaN-based LEDs. The results obtained within this work support the hypothesis on the importance of Auger recombination in determining the so-called efficiency droop in LED structures.
Spatial/spectral encoding of the spin interactions in ultrafast multidimensional NMR
Authors: Shrot Yoav , Frydman Lucio
Published: December 2009

Two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy provides the means to extract diverse physical, chemical, and biological information at an atomic level. Conventional sampling schemes, however, may result in relatively long 2D experiments; this has stimulated the search for alternative, rapid acquisition schemes. Among the strategies that have been recently proposed for achieving this counts an “ultrafast” approach, relying on the spatial encoding of the indirect domain evolution to provide arbitrary spectra within a single scan. A common feature of all spatial encoding schemes hitherto described is their uniform encoding of a continuous bandwidth of indirect-domain frequencies, regardless of the chemical sites’ spectral distribution within it. These very general conditions, however, are often associated with a number of tradeoffs and compromises in the spectral widths and resolutions that can be achieved for both the direct and indirect domains. This paper proposes a different strategy for single-scan acquisition of 2D spectra, which performs an optimal encoding by employing a priori information regarding the positions of NMR resonances along the indirect domain. We denote this as “spatial/spectral encoding”; the underlying principles of this new approach, together with experimental results based on uni- and multidimensional rf pulse schemes, are presented.
Biomolecular papain thin films grown by matrix assisted and conventional pulsed laser deposition: A comparative study
Authors: György E. , Pérez del Pino A. , Sauthier G. , Figueras A.
Published: December 2009

Biomolecular papain thin films were grown both by matrix assisted pulsed laser evaporation (MAPLE) and conventional pulsed laser deposition (PLD) techniques with the aid of an UV KrF∗ (λ=248 nm, τFWHM≅20 ns) excimer laser source. For the MAPLE experiments the targets submitted to laser radiation consisted on frozen composites obtained by dissolving the biomaterial powder in distilled water at 10 wt % concentration. Conventional pressed biomaterial powder targets were used in the PLD experiments. The surface morphology of the obtained thin films was studied by atomic force microscopy and their structure and composition were investigated by Fourier transform infrared spectroscopy. The possible physical mechanisms implied in the ablation processes of the two techniques, under comparable experimental conditions were identified. The results showed that the growth mode, surface morphology as well as structure of the deposited biomaterial thin films are determined both by the incident laser fluence value as well as target preparation procedure.
Assessment of stress contributions in GaN high electron mobility transistors of differing substrates using Raman spectroscopy
Authors: Beechem Thomas , Christensen Adam , Green D. S. , Graham Samuel
Published: December 2009

The capability of gallium nitride (GaN) high power transistors arises, in large part, due to piezoelectric polarizations that induce the formation of a carrier rich two-dimensional electron gas. These polarizations, in turn, are directly related to the strain and hence stress that is present within the transistor. As a consequence, the stress load, as well as its measurement, is extremely important to the optimization of this device class. In response, this study demonstrates a technique to quantify the magnitude of operational thermoelastic stress that evolves in a GaN transistor through simultaneous use of the Raman signal’s Stokes peak position and linewidth. After verifying the technique through comparison with a finite element model, the method is then utilized in the analysis of high electron mobility transistors grown on silicon (Si) and silicon carbide (SiC) substrates. For each series of device, the major stress contributors—thermoelastic, converse piezoelectric, and residual—are acquired and compared. While the magnitudes of the components are larger in those devices grown on silicon, the resultant biaxial loads in each of the devices are comparable at high power levels as the dominant residual tensile stress is counterbalanced by the compressive thermoelastic contribution.
Surface acoustic waves in a periodically patterned layered structure
Authors: Maznev A. A. , Every A. G.
Published: December 2009

Dispersion relations of surface acoustic modes in a supported film with periodic mass loading at the surface are calculated using the plane wave expansion method. The model captures the salient features of recent experiments on the laser excitation of surface waves in periodically patterned thin film structures, such as a bandgap inside the Brillouin zone arising from the hybridization and avoided crossing of the Rayleigh and Sezawa modes. We demonstrate that the ellipticity of the particle motion in the surface waves plays an important role in determining the width of the bandgaps. In particular, bandgaps at the Brillouin zone boundary close completely when the surface particle motion in a given acoustic mode becomes circular. Another interesting finding is that of an isolated point within the leaky Rayleigh–Sezawa branch where the periodicity-induced attenuation vanishes.
Three types of dissociated misfit dislocations in epitaxial Ba0.3Sr0.7TiO3 thin films grown on (001) LaAlO3
Authors: Lu C. J. , Li Chao , Zhang Y. C. , Ye W. N. , Shan F. K. , Xia L. H.
Published: December 2009

Three types of dissociated misfit dislocations (MDs) in epitaxial Ba0.3Sr0.7TiO3 thin films grown on (001) LaAlO3 have been studied by high-resolution transmission electron microscopy. First, a MD with b=[101] dissociates into two edge partials and results in the incline of film lattice. Second, a [110] MD is split into two (1/2)[110] partials of mixed character. In the third case, a [110] MD of mixed character is composed of three partials which are reacted with two (1/2)⟨110⟩ stacking faults. Neither of the three types of dissociation reactions has been reported before for MDs in perovskite thin films.
Preparation of semiconductor nanospheres by laser-induced phase separation
Authors: Qin Wen-Jing , Kulinich Sergei A. , Yang Xiao-Bo , Sun Jing , Du Xi-Wen
Published: December 2009

Semiconductor nanospheres were efficiently synthesized by the pulsed-laser-ablation-in-liquid technique applied to suspensions of certain powders. The nanosphere formation is demonstrated to follow a solid phase separation mechanism and take place in a low-temperature zone of the laser-irradiated volume, while the high temperature and rapid cooling rate generated by pulsed laser are crucial for the particle shape. The synthetic route is applied to different material systems and proved to be a general way for manufacturing various high-quality nanostructures with spherical shape.
Mg segregation in Mg-rich Mg–Ni switchable mirror studied by Rutherford backscattering, elastic recoil detection analysis, and nuclear reaction analysis
Authors: Sekiba D. , Horikoshi M. , Abe S. , Ishii S.
Published: December 2009

Pd / Mg 3.3 Ni films were prepared by dc sputtering deposition on three different substrates of glass, diamondlike carbon/Si, and Si. Hydrogenation and dehydrogenation cycles were performed on these samples simultaneously. The optical switching property due to the hydrogenation and dehydrogenation was monitored by the transmission of laser light via the glass substrate. The switching ability was totally lost after 120 cycles. We made comparative study of the composition change between the new (as-deposited) and old (after 120 switching cycles) samples by Rutherford backscattering (RBS), elastic recoil detection analysis (ERDA), and nuclear reaction analysis (NRA). From the RBS results we found out the segregation of a Mg layer between the Pd cap layer and the rest of the Mg–Ni layer. At the Pd/Mg interface in the old sample, thin MgO layer formed probably during the dehydrogenation process with O2. ERDA showed that there is much hydrogen in the old sample. NRA displayed the depth profiles of hydrogen distribution in the old sample. It is revealed that much hydrogen is accumulated at the interface between the Pd cap layer and the segregated Mg layer. It can be concluded that the formations of oxide and hydride of the segregated Mg layer are the main reasons for the degradation of the Mg3.3Ni switchable mirror.
On a regularity criterion for the Navier–Stokes equations involving gradient of one velocity component
Authors: Zhou Yong , Pokorný Milan
Published: December 2009

We improve the regularity criterion for the incompressible Navier–Stokes equations in the full three-dimensional space involving the gradient of one velocity component. The method is based on recent results of Cao and Titi [see “Regularity criteria for the three dimensional Navier–Stokes equations,” Indiana Univ. Math. J. 57, 2643 (2008)] and Kukavica and Ziane [see “Navier-Stokes equations with regularity in one direction,” J. Math. Phys. 48, 065203 (2007)]. In particular, for s∊[2,3], we get that the solution is regular if ∇u3∊Lt(0,T;Ls(R3)), 2/t+3/s≤2312.
Structural aspects of the solvation shell of lysine and acetylated lysine: A Car–Parrinello and classical molecular dynamics investigation
Authors: Carnevale V. , Raugei S.
Published: December 2009

Lysine acetylation is a post-translational modification, which modulates the affinity of protein-protein and/or protein-DNA complexes. Its crucial role as a switch in signaling pathways highlights the relevance of charged chemical groups in determining the interactions between water and biomolecules. A great effort has been recently devoted to assess the reliability of classical molecular dynamics simulations in describing the solvation properties of charged moieties. In the spirit of these investigations, we performed classical and Car–Parrinello molecular dynamics simulations on lysine and acetylated-lysine in aqueous solution. A comparative analysis between the two computational schemes is presented with a focus on the first solvation shell of the charged groups. An accurate structural analysis unveils subtle, yet statistically significant, differences which are discussed in connection to the significant electronic density charge transfer occurring between the solute and the surrounding water molecules.
Universal divergenceless scaling between structural relaxation and caged dynamics in glass-forming systems
Authors: Ottochian A. , De Michele C. , Leporini D.
Published: December 2009

On approaching the glass transition, the microscopic kinetic unit spends increasing time rattling in the cage of the first neighbors, whereas its average escape time, the structural relaxation time τα, increases from a few picoseconds up to thousands of seconds. A thorough study of the correlation between τα and the rattling amplitude, expressed by the Debye–Waller factor, was carried out. Molecular-dynamics simulations of both a model polymer system and a binary mixture were performed by varying the temperature, the density ρ, the potential and the polymer length to consider the structural relaxation as well as both the rotational and the translation diffusion. The present simulations, together with MD studies on other glassformers, evidence the scaling between the structural relaxation and the caged dynamics. An analytic model of the master curve is developed in terms of two characteristic length scales a2¯ 1/2 and σa21/2, pertaining to the distance to be covered by the kinetic unit to reach a transition state. The model does not imply τα divergences. The comparison with the experiments supports the numerical evidence over a range of relaxation times as wide as about eighteen orders of magnitude. A comparison with other scaling and correlation procedures is presented. In particular, the density scaling of the length scales a2¯ 1/2, σa21/2∝ρ−1/3 is shown to be not supported by the present simulations. The study suggests that the equilibrium and the moderately supercooled states of the glassformers possess key information on the huge slowing-down of their relaxation close to the glass transition. The latter, according to the present simulations, exhibits features consistent with the Lindemann melting criterion and the free-volume model.
Self-consistent potentials and linear regime conductance of cylindrical nanowire transistors in the R-matrix formalism
Authors: Nemnes G. A. , Ion L. , Antohe S.
Published: December 2009

One of the major difficulties in solving the coupled Schrödinger–Poisson equations for open quantum systems is providing the wave functions for a large energy set. In this context, the R-matrix formalism provides an alternative method to obtain efficiently the wave functions. In a first step, which is energy independent, the eigenvalue problem associated with the quantum system is solved only once using fixed boundary conditions. Then, in a second step, the wave functions and transmission coefficients are obtained with a much lower computational effort for each energy. As an application, self-consistent potential and charge distribution, as well as the ballistic source-drain conductance, are calculated for a cylindrical nanowire transistor. The numerical accuracy with respect to basis cardinality is also discussed.