bluuebunny/crossref_metadata_2025 huggingface dataset:
Musical characteristics of Enka
Authors: Maki Okada
Published: November 2008

This paper presents an analysis of enka, a type of Japanese popular song. I shall attempt to elucidate the musical characteristics of enka by examining its musical scales, melodies, vocal techniques and rhythms. We shall see, however, that enka is a composite genre, not characterised by a single type of scale or rhythm. Furthermore, it is virtually impossible to understand enka without reference to other types of Japanese popular song. Thus some discussion of such other genres will also be required.
Some aspects of Japanese popular music
Authors: Junko Kitagawa
Published: November 2008

In 1959, the Conlon report, a presentation of United States government policies in relation to Asian cultures, stated the following about Japanese culture (in a section titled ‘Social change’):

Developments within and among the various Japanese social classes suggest the dynamic, changing quality of modern Japan … No area of Japan, moreover, is beyond the range of the national publications, radio, and even TV. New ideas can be quickly and thoroughly disseminated; it is in this sense that Japanese culture can become more standardised even as it is changing. Many of the changes look in the direction of the United States; in such diverse fields as gadgets, popular music, and fashions. American influence is widespread. And this is but one evidence of the general desire to move away from the spartan, austere past toward a more comfortable, convenient future.
Cathy's homecoming and the Other world: Kate Bush's ‘Wuthering Heights’
Authors: Losseff Nicky
Published: November 2008

Curiosity value quite possibly accounted for the success of Kate Bush's first single in 1978. Those who have continued to admire her more particularly for her later musical achievements, which have surely consolidated her position as one of the most individual and innovative artists of the 1980s and 1990s, do so possibly in spite of (rather than because of) the impact of ‘Wuthering Heights’. No other song of hers has had the same public appeal – it stayed in the British charts for seventy-five weeks (Rice 1991) – and perhaps the smaller group of admirers who remain loyal engage more with the intensely personal visions into which her lyrics have matured, as opposed to that first, more musically zany, original hit.
Cantopop and Mandapop in pre-postcolonial Hong Kong: identity negotiation in the performances of Anita Mui Yim-Fong
Authors: Witzleben J. Lawrence
Published: November 2008

The following comments appeared on the front page of the Hong Kong newspaper South China Morning Post on 19 January 1989, in a story about a performance in the Chinese city of Guangzhou (Canton) by Hong Kong singer Anita Mui YimFong .
‘Let's Hurt Someone’: Violence and Cultural Memory in the Plays of Neil LaBute
Authors: Saal Ilka
Published: November 2008

In this essay Ilka Saal examines one of the most perplexing aspects of Neil LaBute's work: his deployment of excessive and gratuitous violence. She insists that such deployment of violence has little to do with a humanist critique of the propensity for evil in all of us, nor with the playwright's biography (as suggested by a number of critics), but instead functions as a satirical interrogation of the mythological significance attributed to violence in American culture. The casual cruelties of LaBute's ordinary mid-Americans point up the central and ‘ordinary’ role that violence has played in the nation's history and self-understanding. Focusing on the example of the one-act play a gaggle of saints and drawing on the theories of Jan Assmann and Richard Slotkin, she shows in what ways LaBute uses violence to interrogate the country's cultural memory and to alert us to the general lethargy that has settled over the nation with regard to the historical violence it systematically exerted against its Others. Ilka Saal received her PhD in Literature from Duke University, North Carolina and is now working as Associate Professor of English at the University of Richmond, Virginia, where she teaches modern and contemporary American literature and culture. She is the author of New Deal Theater: the Vernacular Tradition in American Political Theater (Palgrave Macmillan, 2007), Dramatizing the Disease: Representations of AIDS on the US American Stage (Tectum, 1997), and co author of Passionate Politics: the Cultural Work of American Melodrama from the Early Republic to the Present (Cambridge Scholars Press, 2008).
‘Did You Watch the Man or Did You Watch the Goose?’ Children's Responses to Puppets in Live Theatre
Authors: Reason Matthew
Published: November 2008

Puppets are inanimate objects that, when watched by an audience, are invested with life and motion and character. This is particularly the case, we imagine, with children's theatre, where there is a cultural assumption that young audiences engage with the illusion and imaginative experience. In this article Matthew Reason uses innovative visual arts-based audience research to explore this question, asking how children respond to puppets in live theatre. In doing so he engages with questions of reality, illusion, belief, and disbelief in the theatre, as well as with questions about the respect and sophistication of young audiences. Matthew Reason is a Senior Lecturer in Theatre and Head of Programme for MA Studies in Creative Practice at York St John University. In 2006 he published Documentation, Disappearance, and the Representation of Live Performance (Palgrave), and a full-length exploration of children's experiences of live theatre, The Young Audience, will be published by Trentham Books in 2010.
On a variant of sum-product estimates and explicit exponential sum bounds in prime fields
Authors: BOURGAIN J. , GARAEV M. Z.
Published: November 2008

Let Fp be the field of a prime order p and F*p be its multiplicative subgroup. In this paper we obtain a variant of sum-product estimates which in particular implies the bound

for any subset A ⊂ Fp with 1 < |A| < p12/23. Then we apply our estimate to obtain explicit bounds for some exponential sums in Fp. We show that for any subsets X, Y, Z ⊂ F*p and any complex numbers αx, βy, γz with |αx| ≤ 1, |βy| ≤ 1, |γz| ≤ 1, the following bound holds:

We apply this bound further to show that if H is a subgroup of F*p with |H| > p1/4, then

Finally we show that if g is a generator of F*p then for any M < p the number of solutions of the equation

is less than $M^{3-1/24+o(1)}\Bigl(1+(M^2/p)^{1/24}\Bigr).$. This implies that if p1/2 < M < p, then
Period polynomials and explicit formulas for Hecke operators on Γ0(2)
Authors: FUKUHARA SHINJI , YANG YIFAN
Published: November 2008

Let Sw+2(Γ0(N)) be the vector space of cusp forms of weight w + 2 on the congruence subgroup Γ0(N). We first determine explicit formulas for period polynomials of elements in Sw+2(Γ0(N)) by means of Bernoulli polynomials. When N = 2, from these explicit formulas we obtain new bases for Sw+2(Γ0(2)), and extend the Eichler–Shimura–Manin isomorphism theorem to Γ0(2). This implies that there are natural correspondences between the spaces of cusp forms on Γ0(2) and the spaces of period polynomials. Based on these results, we will find explicit form of Hecke operators on Sw+2(Γ0(2)). As an application of main theorems, we will also give an affirmative answer to a speculation of Imamoglu and Kohnen on a basis of Sw+2(Γ0(2)).
Aging, fitness and muscular performance
Authors: Fowlie Stephen
Published: November 2008

A decrease in habitual physical activity accompanies old age in mammalian species and in healthy man.74,142This is not simply a consequence of a parallel decline in exercise capacity, and factors other than those which limit aerobic capacity and endurance performance must be involved.143Moreover, most old people remain at least moderately active.144Everyday activities may require cardiorespiratory and muscle performance which is much nearer the maximum in elderly individuals than in younger people and further reduction in reserves by, for example, illness, will more readily cause disability.

Regular moderate activity is sufficient to mitigate declining exercise capacity and muscle performance and conditioning programmes may well confer additional benefits even at advanced ages. Exercise remains good for you regardless of age. A suitable programme is one of moderate to high workrates, involving large muscle groups and performed for 15–30 minutes every other day.145The intensity is best guided by heart rate, for which a variety of formulae have been proposed.146

The complex interaction of physiological factors influencing muscular performance has been illustrated. Only when these physiological processes are disentangled and better defined will we elucidate the molecular mechanisms which underlie age-associated changes. It is not yet possible to define the relative importance of intrinsic and extrinsic influences, but the proportion of the decline in VO2max which is directly attributable to intrinsic aging is smaller than is usually assumed, probably less than 50%.147While the most critical determinant of VO2max in young subjects is probably cardiac output,148we now recognize that in elderly people the balance shifts; muscle performance, changes in blood distribution and peripheral microvascular capacity become ever more important determinants of exercise performance and should command increasing research interest.
Amazonian biomass burning‐derived acid and nutrient deposition in the north Andean montane forest of Ecuador
Authors: Boy Jens , Rollenbeck Rütger , Valarezo Carlos , Wilcke Wolfgang
Published: November 2008

We explored the influence of biomass burning in Amazonia and northeastern Latin America on N, C, P, S, K, Ca, Mg, Al, Mn, and Zn cycles of an Andean montane forest in south Ecuador exposed to the Amazon basin between May 1998 and April 2003. We assessed the response of the element budget of three microcatchments (8–13 ha) to the variations in atmospheric deposition between the intensive burning season and outside the burning season in Amazonia. There were significantly elevated H, N, and Mn depositions during biomass burning. Elevated H deposition during biomass burning caused elevated base metal loss from the canopy and the organic horizon and deteriorated already low base metal supply of the vegetation. N was only retained during biomass burning but not during nonfire conditions when deposition was much smaller. We conclude that biomass burning‐related aerosol emissions in Amazonia are large enough to substantially increase element deposition at the western rim of Amazonia. Particularly the related increase of acid deposition impoverishes already base metal scarce ecosystems. As biomass burning is most intense during El Niño situations, a shortened El Niño–Southern Oscillation cycle because of global warming likely enhances the acid deposition at our study forest.
Is the data collection period of the Large‐Scale Biosphere‐Atmosphere Experiment in Amazonia representative of long‐term climatology?
Authors: Rosolem Rafael , Shuttleworth William James , de Gonçalves Luis Gustavo Gonçalves
Published: November 2008

The Large‐Scale Biosphere‐Atmosphere Experiment in Amazonia (LBA) sampled surface‐atmosphere flux exchanges and related ecohydrometeorological processes at several flux tower sites in the Amazonian region between 1999 and 2006. This extensive database is now being analyzed to investigate, for example, the carbon balance of the Amazon basin and the effect of land use change in the basin on climate. It is therefore important to establish whether the period during which these data were collected is representative of the long‐term climatology for the region. This study analyzed long‐term climate station data for stations located nearby the LBA eddy flux tower sites. Measurements taken during the period of data collection were compared with the long‐term station climatology using the Kolmogorov‐Smirnov test and analysis of histogram from random samples from the long‐term climatological record. In terms of precipitation, the LBA data collection period is statistically consistent with the climatology for all LBA study sites. In terms of temperature, the same result is true for most flux station sites; the main exception being the Bananal Island site where the temperature during the LBA period is significantly warmer by about 1°C. There were some short periods when temperature in the region of other LBA flux sites was also statistically different (higher) during the LBA data collection period and an average but not statistically significant tendency toward higher temperatures across the whole region during the LBA period relative to previous years. This is probably because there has been significant land cover change near some of the LBA study sites, but a contribution from climate warming cannot be ruled out.
Phase changes of ambient particles in the Southern Great Plains of Oklahoma
Authors: Martin Scot T. , Rosenoern Thomas , Chen Qi , Collins Donald R.
Published: November 2008

A new instrument, a 1 × 3 tandem differential mobility analyzer (1 × 3‐TDMA), was deployed in June 2007 in the Southern Great Plains, Oklahoma, USA to study the phase of ambient particles. Its primary measurement, the irreversibility of the hygroscopic growth factor, is obtained by reversibly cycling relative humidity (RH) by ±8% and testing for irreversible changes in diameter. In 101 runs, efflorescence occurred 72% of the time for particles sampled at ambient RH. Deliquescence occurred in 13% of the runs. The more frequent occurrence of efflorescence compared to deliquescence was explained at least in part by the distribution of ambient RH, which had a median of 80% and quartiles of 65% and 93% RH. The deliquescence and efflorescence events were nearly exclusive from one another and could be separated by Min[RH Ambient, Inlet RH] <40% for deliquescence and Max[RH Ambient, Inlet RH] >50% for efflorescence. In outlook, the data set from the 1 × 3‐TDMA regarding the phase and hence water content of ambient particles can be used for validating regional chemical transport models of particle phase.
The role of vorticity fluxes in the dynamics of the Zapiola Anticyclone
Authors: Volkov Denis L. , Fu Lee‐Lueng
Published: November 2008

The Argentine Basin in the South Atlantic Ocean is one of the most energetic regions in the ocean with complicated dynamics, which plays an important role in the global climate. A number of observations have discovered an intense anticyclonic gyre of barotropic circulation around the Zapiola Rise in the center of the basin. Theoretical studies have shown that the Zapiola Anticyclone represents an eddy‐driven flow controlled by bottom friction. Recent advances in high‐resolution global‐ocean data syntheses, performed using NASA supercomputing facilities, provide realistic simulations of the circulation and the variability in the Argentine Basin. Using these simulations and satellite altimeter observations, we analyzed the vorticity balance of the Zapiola Anticyclone. Our results suggest the dominance of vorticity fluxes and the advection of the potential vorticity over a nonuniform bottom topography in determining the variability of the gyre, while the impact of the local wind stress is small. The divergence of the relative vorticity anomaly advection by eddies is found to be the most important contributor to the relative vorticity flux divergence influencing the variability of the Zapiola Anticyclone. Our results demonstrate that the relative vorticity influencing the variability of the anticyclone is mainly advected from the south where the northern branch of the Antarctic Circumpolar Current at the Subpolar Front is located.
Venus Express/VIRTIS observations of middle and lower cloud variability and implications for dynamics
Authors: McGouldrick K. , Baines K. H. , Momary T. W. , Grinspoon D. H.
Published: November 2008

We present an analysis of Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) data, carried out to characterize the morphological, geographical, and evolutionary trends of the middle and lower cloud features that are observed in the atmosphere of Venus as variations in brightness temperatures in specific near‐infrared wavelengths. In this preliminary study, we analyze only data collected over the span of 11 orbits. The mean radiance as a function of latitude is consistent with previous ground‐based observations, indicating that the overall global distribution of mean cloud cover is stable, at least on a 10‐ to 20‐year time scale. In contrast with the consistent level of radiance at high latitudes, a significant amount of variability to the radiance exists at lower latitudes, consistent with significant convective activity in the lower and middle cloud decks. The morphology of the holes tends from highly variable orientations of features with aspect ratios of nearly one at low latitudes, to very large aspect ratios and zonally oriented features at higher latitudes. The peak radiance of the holes appears not to demonstrate a latitudinal tendency. There is evidence of more variability to the morphology and radiance of features at lower latitudes. To investigate the evolution of the holes, we examine a sequence of images taken over a 5 h span of a single orbit. If this limited amount of data is representative, then the typical e‐folding time scale for the evolution of a hole is about 1 day.
Degradation of Victoria crater, Mars
Authors: Grant John A. , Wilson Sharon A. , Cohen Barbara A. , Golombek Matthew P. , Geissler Paul E. , Sullivan Robert J. , Kirk Randolph L. , Parker Timothy J.
Published: November 2008

The ∼750 m diameter and ∼75 m deep Victoria crater in Meridiani Planum, Mars, is a degraded primary impact structure retaining a ∼5 m raised rim consisting of 1–2 m of uplifted rocks overlain by ∼3 m of ejecta at the rim crest. The rim is 120–220 m wide and is surrounded by a dark annulus reaching an average of 590 m beyond the raised rim. Comparison between observed morphology and that expected for pristine craters 500–750 m across indicates that the original, pristine crater was close to 600 m in diameter. Hence, the crater has been erosionally widened by ∼150 m and infilled by ∼50 m of sediments. Eolian processes are responsible for most crater modification, but lesser mass wasting or gully activity contributions cannot be ruled out. Erosion by prevailing winds is most significant along the exposed rim and upper walls and accounts for ∼50 m widening across a WNW–ESE diameter. The volume of material eroded from the crater walls and rim is ∼20% less than the volume of sediments partially filling the crater, indicating eolian infilling from sources outside the crater over time. The annulus formed when ∼1 m deflation of the ejecta created a lag of more resistant hematite spherules that trapped <10–20 cm of darker, regional basaltic sands. Greater relief along the rim enabled meters of erosion. Comparison between Victoria and regional craters leads to definition of a crater degradation sequence dominated by eolian erosion and infilling over time.
Implementation of Collaborative E-Supply-Chain Initiatives: An Initial Challenging and Final Success Case from Grocery Retailing
Authors: Pramatari Katerina , Evgeniou Theodoros (Theos) , Doukidis Georgios
Published: November 2008

We discuss the challenges of implementing an Internet-based platform for creating collaborative supply chains using a case study in the retail sector. The case presents how an Internet-based collaboration platform was implemented to address the strategic issue of increasing shelf availability and customer service in grocery retailing, an issue that has emerged as one of the major confrontations for the whole sector over the past years. The case presented shows the challenges of executing such strategic collaborative supply-chain initiatives which, although arguably beneficial, can be hindered by IT adoption failures. A longitudinal view of the case is presented, from an initial pilot back in 2001 to the final success in 2005. We discuss the particular challenges of the execution of Internet-enabled collaborative supply-chain initiatives as well as possible managerial actions through a simple framework we develop based on the lessons from the case.
Dynamic control and information processing in the Belousov–Zhabotinsky reaction using a coevolutionary algorithm
Authors: Toth Rita , Stone Christopher , Adamatzky Andrew , de Lacy Costello Ben , Bull Larry
Published: November 2008

We propose that the behavior of nonlinear media can be controlled dynamically through coevolutionary systems. In this study, a light-sensitive subexcitable Belousov–Zhabotinsky reaction is controlled using a heterogeneous cellular automaton. A checkerboard image comprising of varying light intensity cells is projected onto the surface of a catalyst-loaded gel resulting in rich spatiotemporal chemical wave behavior. The coevolved cellular automaton is shown to be able to either increase or decrease chemical activity through dynamic control of the light intensity within each cell in both simulated and real chemical systems. The approach is then extended to construct a number of simple logical functions.
Characteristics of Al2O3 gate dielectrics partially fluorinated by a low energy fluorine beam
Authors: Kim Sung Woo , Park Byoung Jae , Kang Se Koo , Kong Bo Hyun , Cho Hyung Koun , Yeom Geun Young , Heo Sungho , Hwang Hyunsang
Published: November 2008

The partial fluorination of Al2O3 gate dielectrics was examined by exposing an oxide-nitride-aluminum oxide (ONA) stack to a low energy fluorine beam, and its effect on the properties of the ONA was investigated. Exposing ONA to about 10 eV fluorine beam resulted in a 5-nm-thick AlOxFy layer on the ONA by replacing some Al–O to Al–F. The electrical properties such as leakage current and memory window characteristics were improved after fluorination of the ONA, possibly due to the improved charge trapping characteristics through the formation of an AlOxFy layer on the Al2O3 without changing the blocking layer thickness.
Microstructure and crystal defects in ZnMgO pleated nanosheets
Authors: Wang J. R. , Zhang Y. Z. , Ye Z. Z. , Lu J. G. , He H. P. , Zeng Y. J. , Ma Q. B. , Huang J. Y. , Zhu L. P. , Wu Y. Z. , Yang Y. F. , Gong L.
Published: November 2008

Dislocations in the ZnMgO pleated nanosheets were observed from high-resolution transmission electron microscopy (TEM). The Burgers vector was identified as 1/3⟨112¯3⟩ from the Fourier filtered TEM images. Raman spectra revealed that there were microstructure defects in the ZnMgO nanosheets with the increasing Mg content. The incorporation of the Mg impurities in the ZnMgO nanosheets may promote the congregation of oxygen vacancies and thus facilitate the generation of dislocations. The oxygen deficiency as well as surface dislocations played an important role in determining the optical properties of ZnMgO pleated nanosheets.
Precision shooting: Sampling long transition pathways
Authors: Grünwald Michael , Dellago Christoph , Geissler Phillip L.
Published: November 2008

The kinetics of collective rearrangements in solution, such as protein folding and nanocrystal phase transitions, often involve free energy barriers that are both long and rough. Applying methods of transition path sampling to harvest simulated trajectories that exemplify such processes is typically made difficult by a very low acceptance rate for newly generated trajectories. We address this problem by introducing a new generation algorithm based on the linear short time behavior of small disturbances in phase space. Using this “precision shooting” technique, arbitrarily small disturbances can be propagated in time, and any desired acceptance ratio of shooting moves can be obtained. We demonstrate the method for a simple but computationally problematic isomerization process in a dense liquid of soft spheres. We also discuss its applicability to barrier-crossing events involving metastable intermediate states.
Pressure-energy correlations in liquids. II. Analysis and consequences
Authors: Bailey Nicholas P. , Pedersen Ulf R. , Gnan Nicoletta , Schrøder Thomas B. , Dyre Jeppe C.
Published: November 2008

We present a detailed analysis and discuss consequences of the strong correlations of the configurational parts of pressure and energy in their equilibrium fluctuations at fixed volume reported for simulations of several liquids in the previous paper [N. P. Bailey et al., J. Chem. Phys. 129, 184507 (2008)]. The analysis concentrates specifically on the single-component Lennard-Jones system. We demonstrate that the potential may be replaced, at fixed volume, by an effective power law but not simply because only short-distance encounters dominate the fluctuations. Indeed, contributions to the fluctuations are associated with the whole first peak of the radial distribution function, as we demonstrate by an eigenvector analysis of the spatially resolved covariance matrix. The reason the effective power law works so well depends crucially on going beyond single-pair effects and on the constraint of fixed volume. In particular, a better approximation to the potential includes a linear term, which contributes to the mean values of potential energy and virial, but little to their fluctuations, for density fluctuations which conserve volume. We also study in detail the zero temperature limit of the (classical) crystalline phase, where the correlation coefficient becomes very close, but not equal, to unity, in more than one dimension; in one dimension the limiting value is exactly unity. In the second half of the paper we consider four consequences of strong pressure-energy correlations: (1) analyzing experimental data for supercritical argon we find 96% correlation; (2) we discuss the particular significance acquired by the correlations for viscous van der Waals liquids approaching the glass transition: For strongly correlating viscous liquids knowledge of just one of the eight frequency-dependent thermoviscoelastic response functions basically implies knowledge of them all; (3) we reinterpret aging simulations of ortho-terphenyl carried out by Mossa et al. [Eur. Phys. J. B 30, 351 (2002)], showing their conclusions follow from the strongly correlating property; and (4) we briefly discuss the presence of the correlations (after appropriate time averaging) in model biomembranes, showing that significant correlations may be present even in quite complex systems.
Optimized effective potentials from arbitrary basis sets
Authors: Heaton-Burgess Tim , Yang Weitao
Published: November 2008

We investigate the use of a regularized optimized effective potential (OEP) energy functional and L-curve procedure [T. Heaton-Burgess, F. A. Bulat, and W. Yang, Phys. Rev. Lett. 98, 256401 (2007)] for determining physically meaningful OEPs from arbitrary combinations of finite orbital and potential basis sets. The important issue of the manner in which the optimal regularization parameter is determined from the L-curve perspective is reconsidered with the introduction of a rigorous measure of the quality of the potential generated—that being, the extent to which the Ghosh–Parr exchange energy virial relation is satisfied along the L-curve. This approach yields nearly identical potentials to our previous work employing a minimum derivative condition, however, gives rise to slightly lower exact-exchange total energies. We observe that the ground-state energy and orbital energies obtained from this approach, either with balanced or unbalanced basis sets, yield meaningful potentials and energies which are in good comparison to other (a priori balanced) finite basis OEP calculations and experimental ionization potentials. As such, we believe that the regularized OEP functional approach provides a computationally robust method to address the numerical stability issues of this often ill-posed problem.
Microwave dielectric and Raman scattering studies on bismuth zinc niobate thin films
Authors: Sudheendran K. , Raju K. C. James , Singh Manoj K. , Katiyar Ram S.
Published: November 2008

Bismuth zinc niobate (Bi1.5Zn1.0Nb1.5O7) thin films were deposited on fused silica substrates by pulsed laser deposition. Its phase composition and microstructure were characterized by x-ray diffraction and atomic force microscopy. The as deposited films were amorphous and all of them were crystallized after a postdeposition annealing at 600 °C for 30 min in air. The crystallite size of the films was found to be varying between 31 and 60 nm with respect to the oxygen pressure in the deposition chamber. The films were found to be less oriented with the decreasing crystallite size. The films deposited under different oxygen pressures showed a microwave dielectric permittivity in between 98–124 and a loss tangent in between 0.005 and 0.007 over the X-band frequency range. From the Raman scattering data of the bulk and thin films, it was found that the Raman modes in thin films are relatively more intense and additional Raman modes were appearing in the films in the low frequency range, which reveal that the local symmetry in the films is different from that of the bulk. The variations in the microwave dielectric properties due to processing can be attributed to the change in the local symmetry of the film.
Free flight of an oscillated string pendulum as a tool for the mechanical characterization of an individual polymer nanofiber
Authors: Burman Michael , Arinstein Arkadii , Zussman Eyal
Published: November 2008

The physical principles of a method for the mechanical testing of individual nanofibers are presented. A fiber with an attached mass undergoing a test is considered as a string pendulum. In addition to regular oscillations under the elastic force, the suspended bob performs free flight only under gravity which can be easily tracked. Based on a model developed to analyze the resonant frequency dependence of these flights, the Young’s modulus of the nanofiber was determined. The proposed method was verified with testing of individual nanofibers of nylon-66, which demonstrated the increase in the Young’s modulus for fiber diameters below 500nm.
Laser annealing characteristics of multiple bulk defect populations within DKDP crystals
Authors: DeMange Paul , Carr Christopher W. , Negres Raluca A. , Radousky Harry B. , Demos Stavros G.
Published: November 2008

Laser annealing by pre-exposure to subdamage threshold laser pulses is a well-established method to increase the damage performance of bulk KH2PO4 and KDxH2−xPO4 nonlinear optical materials. The origin of laser-induced damage is believed to be localized absorption by a defect structure, either a light-absorbing foreign nanoparticle or a cluster of stoichiometric defects. It has been recently shown that there are at least three populations of such defect structures in these materials in which pre-exposure to laser pulses of specific fluence and wavelength results in a measurable reduction in their number density or decrease in their susceptibility to damage. In this work, we investigate the annealing characteristics of these three populations of defect structures in DKDP under variable irradiation conditions. The aim is to understand the similarities and differences between these populations in the way they interact with laser light. The results depict distinct behaviors that reveal information on the relationship between the defect populations and their modifications responsible for annealing.
Fluctuation-induced conductivity of polycrystalline Ni doped Cu0.5Tl0.5Ba2Ca2Cu3−yNiyO10−δ (y=, 0.5, 1.0, 1.5) superconductors
Authors: Hassan Najmul , Khan Nawazish A.
Published: November 2008

The fluctuation-induced conductivity of Ni free and Ni doped Cu0.5Tl0.5Ba2Ca2Cu3−yNiyO10−δ (y=0, 0.5, 1.0, 1.5) samples is investigated for comparison of dimensionality of fluctuations above the mean-field critical temperature. The temperature dependence of paraconductivity can be described by a power law following Aslamazov–Larkin (AL) type equations for these polycrystalline superconductors. It is observed from these studies that at higher temperatures, the fluctuations in the order parameter of the carriers follow two-dimensional (2D) AL behavior, whereas at lower temperatures (closer to transition temperature) their behavior is three-dimensional (3D) AL. From the analysis of our results, we have also evaluated the exponents of dimensionality, the coherence lengths, and the crossover temperatures. The crossover temperature from 2D to 3D have substantially been shifted to lower temperatures with increasing Ni doping, which is most likely related to the scattering of the carriers by remnant spins of Ni atoms. These scattering promote a reduction in the coherence length of the carriers along c-axis. These studies have also shown that the carrier concentration in the conducting CuO2 planes is the most essential; the role of antiferromagnetism in the mechanism of superconductivity is secondary.
Universal critical-like scaling of dynamic properties in symmetry-selected glass formers
Authors: Drozd-Rzoska Aleksandra , Rzoska Sylwester J. , Paluch Marian
Published: November 2008

Evidence for a possible general validity of the critical-like behavior of dielectric relaxation time or viscosity τ,η∝(T−TC)−ϕ with ϕ→9 and TC<Tg on approaching glass temperature (Tg) is shown. This universal behavior is found in various systems where the vitrification is dominated by a selected element of symmetry. The supporting evidence was obtained on the basis of the distortion-sensitive, derivative-based analysis of τ(T) data for a rodlike liquid crystalline compound (E7), orientationally disordered crystals (plastic crystals), a colloidal nanofluid system, polymer melt (polystyrene), oligomeric liquid (EPON 828), and low molecular weight glass formers (glycerol, threitol, sorbitol, and 1-propanol). Results presented explain the puzzling experimental artifacts supporting the dynamical scaling model [R. H. Colby, Phys. Rev. E 61, 1783 (2000); B. M. Erwin, R. H. Colby, J. Non-Cryst. Solids 307–310, 225 (2002)]. It is suggested that spin-glass-like systems may be linked to the discussed pattern.
Particle size effect on strength, failure, and shock behavior in polytetrafluoroethylene-Al-W granular composite materials
Authors: Herbold E. B. , Nesterenko V. F. , Benson D. J. , Cai J. , Vecchio K. S. , Jiang F. , Addiss J. W. , Walley S. M. , Proud W. G.
Published: November 2008

The variation of metallic particle size and sample porosity significantly alters the dynamic mechanical properties of high density granular composite materials processed using a cold isostatically pressed mixture of polytetrafluoroethylene (PTFE), aluminum (Al), and tungsten (W) powders. Quasistatic and dynamic experiments are performed with identical constituent mass fractions with variations in the size of the W particles and pressing conditions. The relatively weak polymer matrix allows the strength and fracture modes of this material to be governed by the granular type behavior of agglomerated metal particles. A higher ultimate compressive strength was observed in relatively high porosity samples with small W particles compared to those with coarse W particles in all experiments. Mesoscale granular force chains of the metallic particles explain this unusual phenomenon as observed in hydrocode simulations of a drop-weight test. Macrocracks forming below the critical failure strain for the matrix and unusual behavior due to a competition between densification and fracture in dynamic tests of porous samples were also observed. Numerical modeling of shock loading of this granular composite material demonstrated that the internal energy, specifically thermal energy, of the soft PTFE matrix can be tailored by the W particle size distribution.
Understanding the disorder of the DNA base cytosine on the Au(111) surface
Authors: Kelly Ross E. A. , Lukas Maya , Kantorovich Lev N. , Otero Roberto , Xu Wei , Mura Manuela , Lægsgaard Erik , Stensgaard Ivan , Besenbacher Flemming
Published: November 2008

Using ultrahigh vacuum scanning tunneling microscopy (STM) and ab initio density functional theory, we have investigated in detail structures formed by cytosine on the Au(111) surface in clean ultrahigh vacuum conditions. In spite of the fact that the ground state of this DNA base on the surface is shown to be an ordered arrangement of cytosine one-dimensional branches (filaments), this structure has never been observed in our STM experiments. Instead, disordered structures are observed, which can be explained by only a few elementary structural motifs: filaments, five- and sixfold rings, which randomly interconnect with each other forming bent chains, T junctions, and nanocages. The latter may have trapped smaller structures inside. The formation of such an unusual assembly is explained by simple kinetic arguments as a liquid-glass transition.
Two-dimensional junction identification in multicrystalline silicon solar cells by scanning Kelvin probe force microscopy
Authors: Jiang C.-S. , Moutinho H. R. , Reedy R. , Al-Jassim M. M. , Blosse A.
Published: November 2008

We report on a two-dimensional investigation of the p-n junction in multicrystalline silicon solar cells using scanning Kelvin probe force microscopy (SKPFM). The junction location and depth were identified by SKPFM potential measurement and subsequent data analysis, where a procedure taking bias-voltage-induced changes in the potential and electric field was developed to avoid the effects of surface Fermi level pinning. Device simulation supported the junction identification procedure and showed a possible deviation of ∼40 nm in the junction identification. The two-dimensional electric-field images show that the shape of the junction follows the surface topography of the device, or, in other words, the junction depth is identical over the device.
Polymer stabilized liquid crystal films reflecting both right- and left-circularly polarized light
Authors: Guo Jinbao , Cao Hui , Wei Jie , Zhang Duowei , Liu Fang , Pan Guohui , Zhao Dongyu , He Wanli , Yang Huai
Published: November 2008

A single-layer polymer stabilized liquid crystal (PSLC) film reflecting both right- and left-circularly polarized light has been developed by a wash-out/refill method. The PSLC film was achieved by prefabricating the polymer network with a left-handed helical structure and then refilling a cholesteric liquid crystal with a right-handed helical structure into the network. The reflection intensity of the PSLC film is close to 100% when the pitch lengths of the two opposite helical structures are the same. It was demonstrated that the memory effect of the polymer network is an important mechanism for the resulting film properties.
The three-dimensional structure of an electromagnetically generated dipolar vortex in a shallow fluid layer
Authors: Akkermans R. A. D. , Cieslik A. R. , Kamp L. P. J. , Trieling R. R. , Clercx H. J. H. , van Heijst G. J. F.
Published: November 2008

Many experiments have been performed in electromagnetically driven shallow fluid layers to study quasi-two-dimensional (Q2D) turbulence, the shallowness of the layer commonly is assumed to ensure Q2D dynamics. In this paper, however, we demonstrate that shallow fluid flows exhibit complex three-dimensional (3D) structures. For this purpose we study one of the elementary vortex structures in Q2D turbulence, the dipolar vortex, in a shallow fluid layer. The flow evolution is studied both experimentally and by numerical simulations. Experimentally, stereoscopic particle image velocimetry is used to measure instantaneously all three components of the velocity field in a horizontal plane, and 3D numerical simulations provide the full 3D velocity and vorticity fields over the entire flow domain. It is found that significant and complex 3D structures and vertical motions occur throughout the flow evolution, i.e., during and after the forcing phase. We conclude that the bottom friction is not the main mechanism leading to three-dimensionality of the flow but rather the impermeability of the boundaries. It is further shown that free-surface deformations, i.e., gravity waves, are of minor importance too as a mechanism to generate 3D motion. Furthermore, it is demonstrated that the observations are not due to three-dimensionality introduced by the forcing mechanism but intrinsically due to the flow dynamics itself. The flow evolution is analyzed with respect to its quasi-two-dimensionality by adopting the ratio of “horizontal” to “vertical” kinetic energies, the normalized horizontal divergence, and a measure of the relaxation to a Poiseuille-like profile. An important observation is that, although the relative magnitude of the vertical velocity as compared to the horizontal flow components decreases for decreasing fluid depth, the vertical profile of the horizontal flow relaxes rather slowly to a Poiseuille-like profile, i.e., not faster than the bottom friction time scale.
The effect of TiO2 nanoparticle concentration on conduction mechanism for TiO2-polymer diode
Authors: Yoo K. H. , Kang K. S. , Chen Y. , Han K. J. , Kim Jaehwan
Published: November 2008

Polymer Schottky diodes using p-type poly(3,4-ethylenedioxythiophene:poly (styrenesulfonate) (PEDOT:PSS) doped with various concentrations of n-type TiO2 nanoparticles have been fabricated. Although Al/PEDOT:PSS/Au Schottky diode does not show a clear diode characteristics, the Al∕TiO2-PEDOT:PSS/Au Schottky diode exhibites excellent rectification characteristics. A Schottky diode with highly doped TiO2 nanoparticles (20wt%) shows high forward current having more than three orders of magnitude with respect to pristine PEDOT:PSS Schottky diode. The conduction mechanism of the TiO2 doped Schottky diodes shows best fit of space charge limited conduction process compared to the other mechanisms including Schottky emission and Poole–Frenkel emission.
Absolutely continuous spectrum of a Schrödinger operator on a tree
Authors: Kupin S.
Published: November 2008

We give sufficient conditions for the presence of the absolutely continuous spectrum of a Schrödinger operator on a regular rooted tree without loops (also called regular Bethe lattice or Cayley tree).
Contrast mechanism of magnetic domains in electron acoustic imaging
Authors: Song H. Z. , Li Y. X. , Zhao K. Y. , Zeng H. R. , Hui S. X. , Li G. R. , Yin Q. R.
Published: November 2008

Contrast origin of magnetic domain structure imaged by scanning electron acoustic microscopy (SEAM) is studied by analyzing qualitatively the interaction between an incident electron beam and a sample. Some parameters related to the acoustic signal detected by a piezoelectric transducer are obtained through solving a vibration equation. Contrasted with magnetic domain structures of Terfenol-D and Fe81Ga19 alloys obtained by SEAM in linear and nonlinear (second harmonic) modes, imaging mechanism of magnetic domains is attributed to piezomagnetic coupling mechanism, magnetostrictive coupling mechanism, and thermal-wave coupling mechanism.
Theory of nonlinear creep in polymer glasses
Authors: Chen Kang , Schweizer Kenneth S. , Stamm Rebecca , Lee Eunwoong , Caruthers James M.
Published: November 2008

A statistical segment-scale constitutive equation theory for the nonlinear mechanics and relaxation of polymer glasses recently proposed by two of us is applied to study nonlinear creep and recovery. The key physics resides in a deformation-dependent elastic modulus and alpha relaxation time, which are determined by a segment-displacement-dependent dynamical free energy that quantifies the transient localization and activated hopping processes. For simple creep and recovery, the amplitudes of the instantaneous up- and down strain jumps are equal and exhibit upward deviations from a linear dependence on applied stress due to modulus softening. Nonexponential relaxation indicative of a distribution of alpha relaxation times is incorporated and shown to be crucial in determining the so-called delayed elastic deformation at intermediate times. The amount of delayed recovered strain appears to saturate at long times at a value equal to the total delayed elastic deformation during creep. Calculations of the time-dependent creep compliance covering the linear and nonlinear regimes are presented. Horizontal shifts can collapse the compliance curves at different stress levels onto a master plot as seen experimentally, and the extracted shift factor quantitatively agrees with the a priori computed normalized alpha relaxation time. Calculations for two-step creep at small stress are in reasonable agreement with experiments on poly(methylmethacrylate) glass, although systematic deviations occur at very high applied stresses.
Release of cationic polymer-DNA complexes from the endosome: A theoretical investigation of the proton sponge hypothesis
Authors: Yang Shuang , May Sylvio
Published: November 2008

Polyplexes are complexes composed of DNA and cationic polymers; they are promising transport vehicles for nonviral gene delivery. Cationic polymers that contain protonatable groups, such as polyethylenimine, have been suggested to trigger endosomal escape of polyplexes according to the “proton sponge hypothesis.” Here, osmotic swelling is induced by a decrease in the endosomal pH value, leading to an accumulation of polymer charge accompanied by the influx of Cl− ions to maintain overall electroneutrality. We study a theoretical model of the proton sponge mechanism. The model is based on the familiar Poisson–Boltzmann approach, modified so as to account for the presence of ionizable polyelectrolytes within self-consistent field theory with assumed ground state dominance. We consider polyplexes, composed of fixed amounts of DNA and cationic polymer, to coexist with uncomplexed cationic polymer in an enclosing vesicle of fixed volume. For such a system, we calculate the increase in osmotic pressure upon moderately decreasing the pH value and relate that pressure to the rupture tension of the enclosing membrane. Our model predicts membrane rupture upon pH decrease only within a certain range of free polymer content in the vesicle. That range narrows with increasing amount of DNA. Consequently, there exists a maximal amount of DNA that can be incorporated into a vesicle while maintaining the ability of content release through the proton sponge mechanism.
Ab initio intermolecular potential energy surfaces of the water-rare gas atom complexes
Authors: Makarewicz Jan
Published: November 2008

Highly accurate analytical intermolecular potential energy surfaces (PESs) of the complexes composed of the water molecule and the rare gas (Rg) atom are presented for Rg=He, Ne, Ar, and Kr. These PESs were scanned using the supermolecule coupled cluster singles and doubles including connected triples method [CCSD(T)]. Efficient basis sets including the bond functions (3s3p2d1f1g) enabled the calculation of more than 430 single-point interaction energies for each complex. These energies were utilized to construct the analytical many-body representations of the PESs. They were refined using the interaction energies evaluated at the complete basis set limit in the PES stationary points. In addition, the corrections from the core correlation were calculated for the complexes including He, Ne, and Ar. The many-body PES of XeH2O was built using the ab initio energy values reported by Wen and Jäger [J. Phys. Chem. A 110, 7560 (2006)]. The clear regularities of the equilibrium structure and the potential barriers were found in the RgH2O series. A comparison of the ab initio and experimental PESs of ArH2O [R. C. Cohen and R. J. Saykally, J. Chem. Phys. 98, 6007 (1993)] reveals their close similarity, except for the potential barriers corresponding to the planar saddle points. Their energetic order is different in both PESs. This suggests that an alternative PES with the reversed barriers, consistent with the ab initio ones, could be derived from the experimental data.
Chaos suppression in a spin-torque nano-oscillator
Authors: Xu H. Z. , Chen X. , Liu J.-M.
Published: November 2008

We propose a novel practicable self-control scheme to suppress chaos in a spin-torque nano-oscillator in the presence of spin-polarized dc and ac. The magnetization dynamics is investigated by performing micromagnetic simulation. A complete chaos control diagram is obtained, indicating that employment of this proper self-control scheme over a broad frequency range of the ac can greatly reduce the degree of chaoticity in the oscillator.