bluuebunny/crossref_metadata_2025 huggingface dataset:
An examination of Alzheimer's disease case definitions using Medicare claims and survey data
Authors: Lin Pei‐Jung , Kaufer Daniel I. , Maciejewski Matthew L. , Ganguly Rahul , Paul John E. , Biddle Andrea K.
Published: May 2010

Background

The prevalence and expenditure estimates of Alzheimer's disease (AD) from studies using one data source to define cases vary widely. The objectives of this study were to assess agreement between AD case definitions classified with Medicare claims and survey data and to provide insight into causes of widely varied expenditure estimates.

Methods

Data were obtained from the 1999–2004 Medicare Current Beneficiary Survey linked with Medicare claims (n = 57,669). Individuals with AD were identified by survey, diagnosis, use of an AD prescription medicine, or some combination thereof. We also explored how much health care and drug expenditures vary by AD case definition.

Results

The prevalence of AD differed significantly by case definition. Using survey report alone yielded more cases (n = 1,994 or 3.46%) than diagnosis codes alone (n = 1,589 or 2.76%) or Alzheimer's medication use alone (n = 1,160 or 2.01%). Agreement between case definitions was low, with kappa coefficients ranging from 0.37 to 0.40. Per capita health expenditures ranged from $16,547 to $24,937, and drug expenditures ranged from $2,303 to $3,519, depending on how AD was defined.

Conclusions

Different information sources yield widely varied prevalence and expenditure estimates. Although claims data provided a more objective means for identifying AD cases, survey report identified more cases, and pharmacy data also are an important source for case ascertainment. Using any single source will underestimate the prevalence and associated cost of AD. The wide range of AD cases identified by using different data sources demands caution interpreting cost‐of‐illness studies using single data sources.
The epigenetics of breast cancer
Authors: Jovanovic Jovana , Rønneberg Jo Anders , Tost Jörg , Kristensen Vessela
Published: May 2010

Epigenetic changes can be defined as stable molecular alterations of a cellular phenotype such as the gene expression profile of a cell that are heritable during somatic cell divisions (and sometimes germ line transmissions) but do not involve changes of the DNA sequence itself. Epigenetic phenomena are mediated by several molecular mechanisms comprising histone modifications, polycomb/trithorax protein complexes, small non‐coding or antisense RNAs and DNA methylation. These different modifications are closely interconnected. Epigenetic regulation is critical in normal growth and development and closely conditions the transcriptional potential of genes. Epigenetic mechanisms convey genomic adaption to an environment thereby ultimately contributing towards given phenotype. In this review we will describe the various aspects of epigenetics and in particular DNA methylation in breast carcinogenesis and their potential application for diagnosis, prognosis and treatment decision.
Ergodic properties of semi-hyperbolic functions with polynomial Schwarzian derivative
Authors: Mayer Volker , Urbański Mariusz
Published: April 2010

The ergodic theory and geometry of the Julia set of meromorphic functions on the complex plane with polynomial Schwarzian derivative are investigated under the condition that the function is semi-hyperbolic, i.e. the asymptotic values of the Fatou set are in attracting components and the asymptotic values in the Julia set are boundedly non-recurrent. We first show the existence, uniqueness, conservativity and ergodicity of a conformal measure m with minimal exponent h; furthermore, we show weak metrical exactness of this measure. Then we prove the existence of a σ-finite invariant measure μ absolutely continuous with respect to m. Our main result states that μ is finite if and only if the order ρ of the function f satisfies the condition h > 3ρ/(ρ+1). When finite, this measure is shown to be metrically exact. We also establish a version of Bowen's Formula, showing that the exponent h equals the Hausdorff dimension of the Julia set of f.
Towards a combinatorial representation theory for the rational Cherednik algebra of type G(r, p, n)
Authors: Griffeth Stephen
Published: April 2010

This paper aims to lay the foundations for a combinatorial study, via orthogonal functions and intertwining operators, of category $\mathcal{O}$ for the rational Cherednik algebra of type G(r, p, n). As a first application, a self-contained and elementary proof of the analogue for the groups G(r, p, n), with r > 1, of Gordon's Theorem (previously Haiman's Conjecture) on the diagonal co-invariant ring is given. No restriction is imposed on p; the result for p ≠ r has been proved by Vale using a technique analogous to Gordon's. Because of the combinatorial application to Haiman's Conjecture, the paper is logically self-contained except for standard facts about complex reflection groups. The main results should be accessible to mathematicians working in algebraic combinatorics who are unfamiliar with the impressive range of ideas used in Gordon's proof of his theorem.
Square-free values of quadratic polynomials
Authors: Friedlander J. B. , Iwaniec H.
Published: April 2010

We consider the quadratic polynomial m2 + D and study the asymptotic formula for the number of integers m, 1≤ m ≤ M, for which the values of the polynomial are square-free. We are interested in particular in the question of how small we can take m in relation to D and still have the asymptotic hold.
Sturm-Liouville problems for the p-Laplacian on a half-line
Authors: Binding Paul , Browne Patrick J. , Karabash Illya M.
Published: April 2010

The nonlinear eigenvalue problem

for 0 ≤ x < ∞, fixed p ∈ (1, ∞), and with y′(0)/y(0) specified is studied under various conditions on the coefficients s and q, leading to either oscillatory or non-oscillatory situations.
Singularities in water waves and the Rayleigh–Taylor problem
Authors: FONTELOS M. A. , DE LA HOZ F.
Published: April 2010

We describe, by means of asymptotic methods and direct numerical simulation, the structure of singularities developing at the interface between two perfect, inviscid and irrotational fluids of different densities ρ1 and ρ2 and under the action of gravity. When the lighter fluid is on top of the heavier fluid, one encounters the water-wave problem for fluids of different densities. In the limit when the density of the lighter fluid is zero, one encounters the classical water-wave problem. Analogously, when the heavier fluid is on top of the lighter fluid, one encounters the Rayleigh–Taylor problem for fluids of different densities, with this being the case when one of the densities is zero for the classical Rayleigh–Taylor problem. We will show that both water-wave and Rayleigh–Taylor problems develop singularities of the Moore-type (singularities in the curvature) when both fluid densities are non-zero. For the classical water-wave problem, we propose and provide evidence of the development of a singularity in the form of a logarithmic spiral, and for the classical Rayleigh–Taylor problem no singularities were found. The regularizing effects of surface tension are also discussed, and estimates of the size and wavelength of the capillary waves, bubbles or blobs that are produced are provided.
Acoustic mode scattering from a heat source
Authors: ATASSI O. V. , GILSON J. J.
Published: April 2010

The scattering of an incident acoustic wave by a non-uniform mean flow resulting from a heat source is investigated. The heat source produces gradients in the mean flow and the speed of sound that scatter the incident duct acoustic mode into vortical, entropic, and higher-order acoustic modes. Linear solutions utilizing the compact source limit and nonlinear solutions to the Euler equations are computed to understand how variations in the amplitude and axial extent of the heat source as well as the incident acoustic wave propagation angle and amplitude modify the scattered solution. For plane wave excitation, significant entropy waves are produced as the net heat addition increases at the expense of the transmitted acoustic energy. When the net heat addition is held constant, increasing the axial extent of the heat source results in a reduction of the entropy waves produced downstream and a corresponding increase in the downstream scattered acoustic energy. For circumferential acoustic mode excitations the incident acoustic wave angle, characterized by the cutoff ratio, significantly modifies the scattered acoustic energy. As the propagating mode cutoff ratio approaches unity, a rise in the scattered vortical disturbance and a decrease in the entropic disturbance amplitude is observed. As the cutoff ratio increases, the scattered solution approaches the plane wave results. Moreover, incident acoustic waves with different frequencies and circumferential mode orders but similar cutoff ratios yield similar scattered wave coefficients. Finally, for large amplitude incident acoustic waves the scattered solution is modified by nonlinear effects. The pressure field exhibits nonlinear steepening of the wavefront and the nonlinear interactions produce higher harmonic frequency content which distorts the sinusoidal variation of the outgoing scattered acoustic waves.
Hegemonic overreach vs. imperial overstretch
Authors: FLORIG DENNIS
Published: April 2010

The concept of hegemonic overreach proposes a revision of Kennedy's notion of imperial overstretch that puts more emphasis on policy choices of hegemonic states. Previous long-cycle theories of hegemonic breakdown have focused on the contradiction between the hegemon's growing military-political commitments and its slipping economic capability relative to rising challenger states. Another key contradiction in US foreign policy is between the imperatives of hegemony and the ideology of messianic mission developed long before the US stepped up to its current global role. Hegemonic overreach, driven by this sense of messianic mission, is a major cause of failure in US foreign policy.
MOMENT-BASED INFERENCE WITH STRATIFIED DATA
Authors: Tripathi Gautam
Published: April 2010

Many data sets used by economists and other social scientists are collected by stratified sampling. The sampling scheme used to collect the data induces a probability distribution on the observed sample that differs from the target or underlying distribution for which inference is to be made. If this effect is not taken into account, subsequent statistical inference can be seriously biased. This paper shows how to do efficient semiparametric inference in moment restriction models when data from the target population are collected by three widely used sampling schemes: variable probability sampling, multinomial sampling, and standard stratified sampling.
EMPIRICAL-LIKELIHOOD-BASED CONFIDENCE INTERVALS FOR CONDITIONAL VARIANCE IN HETEROSKEDASTIC REGRESSION MODELS
Authors: Chan Ngai Hang , Peng Liang , Zhang Dabao
Published: April 2010

Fan and Yao (1998) proposed an efficient method to estimate the conditional variance of heteroskedastic regression models. Chen, Cheng, and Peng (2009) applied variance reduction techniques to the estimator of Fan and Yao (1998) and proposed a new estimator for conditional variance to account for the skewness of financial data. In this paper, we apply empirical likelihood methods to construct confidence intervals for the conditional variance based on the estimator of Fan and Yao (1998) and the reduced variance modification of Chen et al. (2009). Simulation studies and data analysis demonstrate the advantage of the empirical likelihood method over the normal approximation method.
Increased risk of invasive pneumococcal disease in haematological and solid-organ malignancies
Authors: WONG A. , MARRIE T. J. , GARG S. , KELLNER J. D. , TYRRELL G. J. ,   the SPAT Group
Published: April 2010

Large-scale population-based studies have reported a significant increase in invasive pneumococcal disease (IPD) in those with underlying haematological or solid-organ malignancy, but limited condition-specific data are available on rates of IPD in the adult population. A retrospective chart review of all patients with IPD (identified prospectively) in the province of Alberta, Canada (population ~3·3 million) was conducted from 2000 to 2004 to study the epidemiology of IPD. Rates of IPD in patients with various haematological and solid-organ malignancies were determined by obtaining the number of these patients at risk from the provincial cancer registry. Compared to the attack rate of IPD in the adult population aged ⩾18 years (11·0 cases/100 000 per year, 95% CI 10·44–11·65), there were significantly increased rates of IPD in those with lung cancer (143·6 cases/100 000 per year, OR 13·4, 95% CI 9·3–19·4, P<0·001) and multiple myeloma (673·9 cases/100 000 per year, OR 62·8, 95% CI 39·6–99·8, P<0·001). More modestly increased rates of IPD were found in those with chronic lymphocytic leukaemia, acute myeloid leukaemia, acute lymphoblastic leukaemia, and Hodgkin's and non-Hodgkin's lymphoma. There was an increased prevalence of serotype 6A in those with these underlying malignancies, but no other serotypes predominated. Fifty-three percent (48/83) of cases were caused by serotypes in the investigational 13-valent pneumococcal conjugate vaccine (PCV13), and 57/83 (69%) of the cases were caused by serotypes in the 23-valent pneumococcal polysaccharide vaccine (PPV23). The incidence of IPD in adults with certain haematological and solid-organ malignancies is significantly greater than the overall adult population. Such patients should be routinely given pneumococcal polysaccharide vaccine; this population could also be targeted for an expanded valency conjugate vaccine.
… And in Response
Authors: ABBATE CAROLYN
Published: April 2010

Twenty years of Cambridge Opera Journal: in view of the journal's place in the discipline, the occasion seemed worth marking. When Roger Parker and Arthur Groos founded Cambridge Opera Journal in 1989, it offered the first forum to the musical community for serious opera criticism that took into account changing orientations in literary studies and seriously engaged with ideology, reception history, and representations of race, class and gender. Subsequent editors – Mary Hunter, Mary Ann Smart, and Emanuele Senici – continued to foster this wide intellectual perspective and to engage with an extraordinary variety of methodologies. For the current issue, we gave carte blanche to authors who contributed in the first two years of publication to reflect on their past work, or on opera studies, or on the journal, either informally as an opinion piece or through new scholarship – and so to measure time by developments in the discipline itself.
Immigration and Asylum in the United Kingdom
Authors: McClean David
Published: April 2010

This piece offers an account of the law relating to immigration and asylum, especially as it affects ministers of religion and those who give religious reasons for seeking asylum. Beside Nicholas Coulton's passionate advocacy,1 this paper must seem bloodless and even unfeeling. It is a revised version of part of a paper for the European Consortium on Church and State Research, an essentially ‘black-letter’ account of one country's national law constructed to a template that enabled comparisons to be drawn. It began with the observation that United Kingdom immigration law is of daunting complexity; only some limited aspects can be addressed here.
The Failure of Proportionality Tests to Protect Christian Minorities in Western Democracies: AlbertavHutterian Brethren of Wilson Colony
Authors: Ogilvie Margaret H.
Published: April 2010

In 1974, the province of Alberta began to issue drivers' licences with photographs of the licence holder but exempted persons who objected to having their photographs taken for religious reasons from the photograph requirement. At that time the Muslim population of Canada was tiny and it was an unspoken assumption that the exemption was created for the Hutterian Brethren who have long had a number of colonies throughout the Prairies. In 2003, the province made photographs mandatory for all licence holders and created a provincial facial recognition data bank for the photographs. The Wilson colony of Hutterites objected to having their photographs taken on the ground that photographs constitute an infringement of the second commandment concerning idols (Exodus 20.4) as they understand it. Without drivers' licences, the colony is unable to make off colony trips to take their produce to market, or their ill members for medical treatment, or to be volunteer firefighters in their surrounding area, that is, the absence of licensed drivers makes it much more difficult for them to sustain their largely self-sufficient agrarian communal way of life which is also a matter of belief (Acts 2.44) without the expense of hiring taxis or outside drivers on an as-needed basis. The province offered a compromise that Hutterite drivers be issued with photograph-free licences but that photographs would still be required for the data base. The colony suggested a photograph-free licence bearing the words, ‘Not to be used for identification purposes’. Neither side accepted the other's proposal and the colony initiated litigation on the ground that the freedom of religion of the Hutterites pursuant to section 2(a) of the Canadian Charter of Rights and Freedoms (the ‘Charter’) had been infringed. The colony succeeded at trial and by a 2–1 decision in the Alberta Court of Appeal but lost in a 4–3 decision in the Supreme Court of Canada because in the view of the majority, written by McLachlin CJC, the photograph requirement was a ‘reasonable limit’ on religious freedom and ‘demonstrably justifiable in a free and democratic society’ under section 1 of the Charter.
The Future of Church Establishment
Authors: Morris Bob
Published: April 2010

We continue to live in the remains – as opposed to the ruins – of a confessional state. Ruins may be picturesque but have no life. Remains, however, do have being. The fact that the remains exist formally only in England does not mean they have no impact elsewhere in the UK. On the contrary, they continue to have life at the very apex of the constitution.
State Schools and Religious Authority: Where to Draw the Line?
Authors: Barber Paul
Published: April 2010

In December 2009 the Supreme Court by the narrowest of margins (5 to 4) found against the Governing Body of JFS (formerly called the Jews' Free School) on the basis of direct race discrimination. Consequently, schools run by Jews, Sikhs and any other faiths that happen also to be an ‘ethnic group’ are barred from giving priority to children who are members of that faith. As is well known, the very broad definition of ‘ethnic group’ was set by the House of Lords in Mandla v Dowell-Lee at a time when the protections afforded by the more recent laws against religious discrimination were lacking. The majority in the Supreme Court evidently, and with some justification, considered that this definition was sufficiently settled law that only a legislative, and not a judicial, intervention could alter it. In contrast, those faiths and denominations that avoid falling into the Mandla trap, may continue to give priority to their members in admission to their schools. A number of commentators have confidently predicted that this case does not therefore affect most other schools with a religious character. Such a conclusion may be somewhat hasty. The minority held that this was a case of indirect, rather than direct, discrimination and, as such, potentially subject to justification. Perhaps the most surprising element of the judgment is that, unlike Mumby J at first instance, a majority of the Justices did not find it self-evident that a Jewish school giving priority to Jewish applicants in its admissions policy was a proportionate means of pursuing a legitimate aim.
1949 and 1999: Making the Geneva Conventions relevant after the Cold
War
Authors: Forsythe David
Published: April 2010

Après un bref survol de l'évolution du droit international humanitaire
et, en parallèle, du droit international des droits de l'homme depuis 1945,
l'auteur pose la question de savoir comment le CICR, en sa qualité de
gardien des Conventions de Genève, comprend aujourd'hui sa tâche. Le texte
publié par le CICR sous le titre « Projet Avenir: les défis, la mission et
les orientations stratégiques » (RICR, no 829, mars 1998, p. 134) lui sert
de point de départ pour son analyse. Produit d'un long processus de
réflexion, ce texte examine les défis posés par les conflits d'aujourd'hui
et tente de définir les lignes de conduite pour l'organisation. L'auteur
approuve en bonne partie les conclusions auxquelles arrive l'étude,
conclusions qui ne s'écarte guère de la ligne suivie jusqu'à ce jour.
Toutefois, le «projet Avenir» ne donne que peu d'indications sur la
stratégie que le CICR entend suivre pour accomplir son mandat découlant des
Conventions de Genève
The Balkan conflict and respect for international humanitarian
law
Authors:   International Committee
                        of the Red Cross
Published: April 2010

In view of the announcement by Javier Solana, Secretary-General of the
North Atlantic Treaty Organization (NATO), authorizing military action
against the Federal Republic of Yugoslavia, the International Committee of
the Red Cross (ICRC) on 24 March 1999 sent a diplomatic note to NATO and the
respective member States, as well as to the Yugoslav authorities, reminding
them of their obligations under international humanitarian law, in
particular the four Geneva Conventions of 1949.
An overview of lava dome evolution, dome collapse and cyclicity at Soufrière Hills Volcano, Montserrat, 2005–2007
Authors: Loughlin S. C. , Luckett R. , Ryan G. , Christopher T. , Hards V. , De Angelis S. , Jones L. , Strutt M.
Published: April 2010

The third episode of lava dome growth at Soufrière Hills Volcano, Montserrat was characterised by higher average magma discharge rates than either previous dome growth episode at this volcano and yet fewer collapses. During sustained dome growth at moderate‐high average rates (>6 m3/s), we identified 2–6 week discharge pulses that each supplied c.20 Mm3 magma from depth. Our observations are consistent with some existing models but we explain discrepancies by a combination of higher volatile contents and higher ascent rates. Cycles of c. 11–16 days were evident in rockfall, LP rockfall and shallow LP earthquake counts related to dome growth and degassing. We speculate that degassing at the conduit margins together with stick‐slip conduit flow may drive these cycles. Only one major collapse >10 Mm3 occurred during the third episode (on May 20, 2006) as a new magma pulse entered the dome and coincided with heavy rainfall.
Resonance zones for electron interaction with plasma waves in the Earth’s dipole magnetosphere. I. Evaluation for field-aligned chorus, hiss, and electromagnetic ion cyclotron waves
Authors: Ni Binbin , Summers Danny
Published: May 2010

Wave-particle interactions are a key influence on radiation belt particle dynamics. Here electron cyclotron resonance with very-low-frequency chorus, extremely-low-frequency hiss, and electromagnetic ion cyclotron waves in the Earth’s dipole magnetosphere is analyzed. In this first of two companion papers, it is assumed that wave propagation is field aligned. The aim of this investigation is to carry out a detailed examination of “resonance zones” in (L,λ) space (where L denotes magnetic shell and λ the magnetic latitude). These zones are regions in which electron cyclotron resonance occurs for a given wave mode and waveband. Identification of resonance zones is a useful aid in the construction of realistic models of radiation belt electron dynamics, and is hence also useful in the interpretation of observational data.
Electronic spectra of jet-cooled isoindoline: Spectroscopic determination of energy difference between conformational isomers
Authors: Tanaka Sei’ichi , Okuyama Katsuhiko
Published: May 2010

The electronic spectra of jet-cooled isoindoline between the electronic ground (S0) state and the ππ∗ lowest-excited singlet state (S1) were observed by the fluorescence excitation and single-vibronic-level dispersed fluorescence methods. The low-frequency progression due to the puckering vibration appeared in both spectra. Analysis of dispersed spectra together with geometry optimization at the level of B3LYP/6-311+G(d) indicated the presence of conformational isomers possessing axial and equatorial N–H bonds with respect to the molecular plane. The 0–0 bands of the axial and equatorial conformers were measured at 37 022 and 36 761 cm−1, respectively. Three common levels in the S1 state accessible from the respective S0-state zero levels were observed. From their transition frequencies, the S0-state energy difference between the isomers was determined to be 47.7±0.2 cm−1, where the axial conformer was more stable. In the S1 state, the energy difference was 213.7±0.2 cm−1, and the equatorial conformer was more stable. The cause of switching from a stable conformation upon excitation is discussed in terms of the electron conjugation between the π∗ orbital in benzene and the lone pair orbital of nitrogen.
Tests of the RPBE, revPBE, τ-HCTHhyb, ωB97X-D, and MOHLYP density functional approximations and 29 others against representative databases for diverse bond energies and barrier heights in catalysis
Authors: Yang Ke , Zheng Jingjing , Zhao Yan , Truhlar Donald G.
Published: May 2010

Thirty four density functional approximations are tested against two diverse databases, one with 18 bond energies and one with 24 barriers. These two databases are chosen to include bond energies and barrier heights which are relevant to catalysis, and in particular the bond energy database includes metal-metal bonds, metal-ligand bonds, alkyl bond dissociation energies, and atomization energies of small main group molecules. Two revised versions of the Perdew–Burke–Ernzerhof (PBE) functional, namely the RPBE and revPBE functionals, widely used for catalysis, do improve the performance of PBE against the two diverse databases, but give worse results than B3LYP (which denotes the combination of Becke's 3-parameter hybrid treatment with Lee–Yang–Parr correlation functional). Our results show that the Minnesota functionals, M05, M06, and M06-L give the best performance for the two diverse databases, which suggests that they deserve more attention for applications to catalysis. We also obtain notably good performance with the τ-HCTHhyb, ωB97X-D, and MOHLYP functional (where MOHLYP denotes the combination of the OptX exchange functional as modified by Schultz, Zhao, and Truhlar with half of the LYP correlation functional).
Kinetic effects on the Kelvin–Helmholtz instability in ion-to-magnetohydrodynamic scale transverse velocity shear layers: Particle simulations
Authors: Nakamura T. K. M. , Hasegawa H. , Shinohara I.
Published: May 2010

Ion-to-magnetohydrodynamic scale physics of the transverse velocity shear layer and associated Kelvin–Helmholtz instability (KHI) in a homogeneous, collisionless plasma are investigated by means of full particle simulations. The shear layer is broadened to reach a kinetic equilibrium when its initial thickness is close to the gyrodiameter of ions crossing the layer, namely, of ion-kinetic scale. The broadened thickness is larger in B⋅Ω<0 case than in B⋅Ω>0 case, where Ω is the vorticity at the layer. This is because the convective electric field, which points out of (into) the layer for B⋅Ω<0 (B⋅Ω>0), extends (reduces) the gyrodiameters. Since the kinetic equilibrium is established before the KHI onset, the KHI growth rate depends on the broadened thickness. In the saturation phase of the KHI, the ion vortex flow is strengthened (weakened) for B⋅Ω<0 (B⋅Ω>0), due to ion centrifugal drift along the rotational plasma flow. In ion inertial scale vortices, this drift effect is crucial in altering the ion vortex size. These results indicate that the KHI at Mercury-like ion-scale magnetospheric boundaries could show clear dawn-dusk asymmetries in both its linear and nonlinear growth.
Relative unitary implementability of perturbed quantum field dynamics on de Sitter space
Authors: Poon Gary Kaiman
Published: May 2010

We study the quantum dynamics of a Klein–Gordon field on de Sitter space based on the Euclidean vacuum. We prove time evolution is not unitarily implementable. We also consider a Klein–Gordon field perturbed by a local potential V. In this case we prove that the deviation from the V=0 dynamics is unitarily implementable.
rf-electrometer using a carbon nanotube resonant tunneling transistor
Authors: Lechner Lorenz G. , Wu Fan , Danneau Romain , Andresen Søren E. , Hakonen Pertti
Published: May 2010

We have studied resonant tunneling transistors (RTT) made of single-walled carbon nanotube quantum dots in the Fabry–Pérot regime. We show sensitivity to input charge as high as 5×10−6 e/Hz1/2 with a carrier frequency of 719 MHz at 4.2 K. This result is comparable to the best values of charge sensitivity so far reported for radio frequency single electron transistors (rf-SET). Unlike SETs, whose operating temperature is limited as Coulomb blockade vanishes as 1/T, a RTT can operate at higher temperatures, since the dephasing length lϕ∝1/T2/3.
Thermal radiation from a converging shock implosion
Authors: Kjellander Malte , Tillmark Nils , Apazidis Nicholas
Published: May 2010

High energy concentration in gas is produced experimentally by focusing cylindrical shock waves in a specially constructed shock tube. The energy concentration is manifested by the formation of a hot gas core emitting light at the center of a test chamber at the instant of shock focus. Experimental and numerical investigations show that the shape of the shock wave close to the center of convergence has a large influence on the energy concentration level. Circular shocks are unstable and the resulting light emission varies greatly from run to run. Symmetry and stability of the converging shock are achieved by wing-shaped flow dividers mounted radially in the test chamber, forming the shock into a more stable polygonal shape. Photometric and spectroscopic analysis of the implosion light flash from a polygonal shock wave in argon is performed. A series of 60 ns time-resolved spectra spread over the 8 μs light flash shows the emission variation over the flash duration. Blackbody fits of the spectroscopic data give a maximum measured gas temperature of 5800 K in the beginning of the light flash. Line emissions originating in transitions in neutral argon atoms from energy levels of up to 14.7 eV were also detected.
Gröbli solution for three magnetic vortices
Authors: Komineas Stavros , Papanicolaou Nikos
Published: May 2010

The dynamics of N point vortices in a fluid is described by the Helmholtz–Kirchhoff (HK) equations which lead to a completely integrable Hamiltonian system for N=2 or 3 but chaotic dynamics for N>3. Here we consider a generalization of the HK equations to describe the dynamics of magnetic vortices within a collective-coordinate approximation. In particular, we analyze in detail the dynamics of a system of three magnetic vortices by a suitable generalization of the solution for three point vortices in an ordinary fluid obtained by Gröbli more than a century ago. The significance of our results for the dynamics of ferromagnetic elements is briefly discussed.
Twinning Ge0.54Si0.46 nanocrystal growth mechanism in amorphous SiO2 films
Authors: Liu L. Z. , Wu X. L. , Li T. H. , Chu Paul K.
Published: May 2010

Ge 0.54 Si 0.46 alloy nanocrystals (NCs) with different twinning structures are synthesized by magnetron sputtering followed by high temperature (>1100 °C) annealing and rapid cooling. The local strain induced by rapid cooling enables neighboring NCs to coalesce quickly. Because of insufficient time to form individual structures, a leading twinning interface forms inevitably in the interior of the NCs. The twinning NCs with large surface free energies reconstruct for energy optimization at high temperature. Consequently, the twinning layer thickness shrinks slowly, finally transforming into untwined stable NCs with the lowest surface free energy. Our experimental observations are corroborated by theoretical calculation.
Note: Characterization of the plasma parameters of a capillary discharge-produced plasma channel waveguide to guide an intense laser pulse
Authors: Higashiguchi Takeshi , Hikida Masafumi , Terauchi Hiromitsu , Bai Jin-xiang , Kikuchi Takashi , Tao Yezheng , Yugami Noboru
Published: May 2010

We demonstrated the production of an optical waveguide in a capillary discharge-produced plasma using a cylindrical capillary. Plasma parameters of its waveguide were characterized by use of both a Nomarski laser interferometer and a hydrogen plasma line spectrum. A space-averaged maximum temperature of 3.3 eV with electron densities of the order of 1017 cm−3 was observed at a discharge time of 150 ns and a maximum discharge current of 400 A. An ultrashort, intense laser pulse was guided by use of this plasma channel.
Topology-energy relationships and lowest energy configurations for pentagonal dodecahedral (H2O)20X clusters, X=empty, H2O, NH3, H3O+: The importance of O-topology
Authors: Anick David J.
Published: May 2010

For (H2O)20X water clusters consisting of X enclosed by the 512 dodecahedral cage, X=empty, H2O, NH3, and H3O+, databases are made consisting of 55–82 isomers optimized via B3LYP/6-311++G∗∗. Correlations are explored between ground state electronic energy (Ee) or electronic energy plus zero point energy (Ee+ZPE) and the clusters’ topology, defined as the set of directed H-bonds. Linear regression is done to identify topological features that correlate with cluster energy. For each X, variables are found that account for 99% of the variance in Ee and predict it with a rms error under 0.2 kcal/mol. The method of analysis emphasizes the importance of an intermediate level of structure, the “O-topology,” consisting of O-types and a list of O pairs that are bonded but omitting H-bond directions, as a device to organize the databases and reduce the number of structures one needs to consider. Relevant variables include three parameters, which count the number of H-bonds having particular donor and acceptor types; |M|2, where M is the cluster’s vector dipole moment; and the projection of M onto the symmetry axis of X. Scatter diagrams for Ee or Ee+ZPE versus |M| show that clusters fall naturally into “families” defined by the values of certain discrete parameters, the “major parameters,” for each X. Combining “family” analysis and O-topologies, a small group of clusters is identified for each X that are candidates to be the global minimum, and the minimum is determined. For X=H3O+, one cluster with central hydronium lies just 2.08 kcal/mol above the lowest isomer with surface hydronium. Implications of the methodology for dodecahedral (H2O)20(NH4+) and (H2O)20(NH4+)(OH−) are discussed, and new lower energy isomers are found. For MP2/TZVP, the lowest-energy (H2O)20(NH4+) isomer features a trifurcated H-bond. The results suggest a much more efficient and comprehensive way of seeking low-energy water cluster geometries that may have wide applicability.
Ionic multilayers at the free surface of an ionic liquid, trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide, probed by x-ray reflectivity measurements
Authors: Nishi Naoya , Yasui Yukinori , Uruga Tomoya , Tanida Hajime , Yamada Tasuku , Nakayama Shun-ichi , Matsuoka Hideki , Kakiuchi Takashi
Published: May 2010

The presence of ionic multilayers at the free surface of an ionic liquid, trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide ([TOMA+][C4C4N−]), extending into the bulk from the surface to the depth of ∼60 Å has been probed by x-ray reflectivity measurements. The reflectivity versus momentum transfer (Q) plot shows a broad peak at Q∼0.4 Å−1, implying the presence of ionic layers at the [TOMA+][C4C4N−] surface. The analysis using model fittings revealed that at least four layers are formed with the interlayer distance of 16 Å. TOMA+ and C4C4N− are suggested not to be segregated as alternating cationic and anionic layers at the [TOMA+][C4C4N−] surface. It is likely that the detection of the ionic multilayers with x-ray reflectivity has been realized by virtue of the greater size of TOMA+ and C4C4N− and the high critical temperature of [TOMA+][C4C4N−].
A near infrared instrument to monitor relative hemoglobin concentrations of human bone tissue in vitro and in vivo
Authors: Aziz Syed Mahfuzul , Khambatta Faram , Vaithianathan Tharshan , Thomas John C. , Clark Jillian M. , Marshall Ruth
Published: May 2010

A continuous wave near infrared instrument has been developed to monitor in vivo changes in the hemoglobin concentration of the trabecular compartment of human bone. The transmitter uses only two laser diodes of wavelengths 685 and 830 nm, and the receiver uses a single silicon photodiode operating in the photovoltaic mode. The functioning of the instrument and the depth of penetration of the near infrared signals was determined in vitro using tissue-equivalent phantoms. The instrument achieves a depth of penetration of approximately 2 cm for an optode separation of 4 cm and, therefore, has the capacity to interrogate the trabecular compartment of human bone. The functioning of the instrument was tested in vivo to evaluate the relative oxy-hemoglobin (HbO2) and deoxy-hemoglobin (Hb) concentrations of the proximal tibial bone of apparently healthy, normal weight, adult subjects in response to a 3 min on, 5 min off, vascular occlusion protocol. The traces of the relative Hb and HbO2 concentrations obtained were reproducible in controlled conditions. The instrument is relatively simple and flexible, and offers an inexpensive platform for further studies to obtain normative data for healthy cohorts, and to evaluate disease-specific performance characteristics for cohorts with vasculopathies of bone.
Reactions of C2(a ∏3u) with selected saturated alkanes: A temperature dependence study
Authors: Hu Renzhi , Zhang Qun , Chen Yang
Published: May 2010

We present a temperature dependence study on the gas phase reactions of the C2(a ∏3u) radical with a selected series of saturated alkanes (C2H6, C3H8, n-C4H10, i-C4H10, and n-C6H14) by means of pulsed laser photolysis/laser-induced fluorescence technique. The bimolecular rate constants for these reactions were obtained between 298 and 673 K. A pronounced negative temperature effect was observed for n-C4H10, i-C4H10, and n-C6H14 and interpreted in terms of steric hindrance of the more reactive secondary or tertiary C–H bonds by less reactive CH3 groups. Detailed analysis of our experimental results reveals quantitatively the temperature dependence of reactivities for the primary, secondary, and tertiary C–H bonds in these saturated alkanes and further lends support to a mechanism of hydrogen abstraction.
Model of sheared granular material and application to surface-driven granular flows under gravity
Authors: Lee Cheng-Hsien , Huang Ching-Jer
Published: May 2010

This work presents a novel model of sheared granular materials that consist of two-dimensional, slightly inelastic, circular disks. To capture the static and kinetic features of the granular flow involving different regimes, both the shear stress and pressure are superimposed by a rate-independent component (representing the static contribution) and a rate-dependent component (representing the kinetic contribution), as determined using granular kinetic theory. The dilatancy law is adopted to close the set of equations, and the constraint that static pressure is non-negative is utilized to determine the transition between the dense regime and the inertial regime. The balance equation of granular temperature incorporates the works done by both the static and kinetic components of shear stress. This enabled the proposed model to predict the hysteretic flow thresholds and the shear bands. Additionally, a thick, surface-driven granular flow under gravity is investigated using the proposed model. The predicted velocity, volume fraction, granular temperature, and stress are consistent with results obtained using the molecular dynamic method. This finding demonstrates the ability of the proposed model to simulate granular flow in which the quasistatic, dense, and kinetic regimes coexist simultaneously.
Stabilization of thin liquid films flowing over locally heated surfaces via substrate topography
Authors: Tiwari Naveen , Davis Jeffrey M.
Published: May 2010

A long-wave lubrication analysis is used to study the influence of topographical features on the linear stability of noninertial coating flows over a locally heated surface. Thin liquid films flowing over surfaces with localized heating develop a pronounced ridge at the upstream edge of the heater. This ridge becomes unstable to transverse perturbations above a critical Marangoni number and evolves into an array of rivulets even in the limit of noninertial flow. Similar fluid ridges form near topographical variations on isothermal surfaces, but these ridges are stable to perturbations. The influence of basic topographical features on the stability of the locally heated film is analyzed. In contrast to its destabilizing influence on liquid films resting on heated, horizontal walls, even such nonoptimized topography is found to be effective at stabilizing the flowing film with respect to rivulet formation and subsequent rupture. Optimal topographical features that suppress variations in the free-surface shape are also determined. The critical Marangoni number at the instability threshold increases substantially with appropriate topography even for nonzero Biot numbers. An energy analysis is used to provide insight into the mechanism by which the topography stabilizes the flow. Because the stabilizing effect of the topographical features is only weakly sensitive to the governing parameters and particular temperature profile, the use of such features could be a simple alternative in applications to more complicated methods of stabilization.
Numerical study of pressure forcing of wind on dynamically evolving water waves
Authors: Liu Yi , Yang Di , Guo Xin , Shen Lian
Published: May 2010

We simulate the dynamic evolution of nonlinear water waves coupled with wind turbulence. We first investigate simple wave trains to obtain pressure distribution, based on which parameters for wave growth are quantified and their dependence on wave age and wave steepness is shown. We then investigate broadband waves to obtain physical insights to wind forcing for phase-resolved wavefield simulation. It is found that for long wave components, the wave growth parameter can be approximated by the value of the corresponding monochromatic waves; for short waves, stochastic modeling is suggested.
Relationship between population of the fibril-prone conformation in the monomeric state and oligomer formation times of peptides: Insights from all-atom simulations
Authors: Nam Hoang Bao , Kouza Maksim , Zung Hoang , Li Mai Suan
Published: May 2010

Despite much progress in understanding the aggregation process of biomolecules, the factors that govern its rates have not been fully understood. This problem is of particular importance since many conformational diseases such as Alzheimer, Parkinson, and type-II diabetes are associated with the protein oligomerization. Having performed all-atom simulations with explicit water and various force fields for two short peptides KFFE and NNQQ, we show that their oligomer formation times are strongly correlated with the population of the fibril-prone conformation in the monomeric state. The larger the population the faster the aggregation process. Our result not only suggests that this quantity plays a key role in the self-assembly of polypeptide chains but also opens a new way to understand the fibrillogenesis of biomolecules at the monomeric level. The nature of oligomer ordering of NNQQ is studied in detail.
Tunneling magnetoresistance on the surface of a topological insulator with periodic magnetic modulations
Authors: Zhang Ya , Zhai Feng
Published: May 2010

We investigate the band and transport features of Dirac electrons on the surface of a three-dimensional topological insulator under the modulation of a periodic exchange field provided by an array of ferromagnetic insulating (FI) stripes. The Dirac point is shifted (unchanged) by the superlattice when the magnetizations of adjacent FI stripes are parallel (antiparallel). For a finite magnetic superlattice, there exists a full transmission gap for both the parallel and antiparallel configurations. When the two kinds of transmission gaps have no overlap, a large magnetoresistance ratio with a tunable sign can be achieved.
Phototransistor with nanocrystalline Si/amorphous Si bilayer channel
Authors: Vygranenko Yuri , Nathan Arokia , Vieira Manuela , Sazonov Andrei
Published: May 2010

We report a field-effect phototransistor with a channel comprising a thin nanocrystalline silicon transport layer and a thicker hydrogenated amorphous silicon absorption layer. The semiconductor and dielectric layers were deposited by radio-frequency plasma enhanced chemical vapor deposition. The phototransistor with channel length of 24 microns and photosensitive area of 1.4 mm2 shows an off-current of about 1 pA, and high photoconductive gain in the subthreshold region. Measurements of the quantum efficiency at different incident light intensities and biasing conditions, along with spectral-response characteristics, and threshold voltage stability characterization demonstrate the feasibility of the phototransistor for low light level detection.
Stochastic resonance in a nanoscale Y-branch switch
Authors: Hartmann F. , Hartmann D. , Kowalzik P. , Forchel A. , Gammaitoni L. , Worschech L.
Published: May 2010

The self-gating effect in a nanoscale Y-branch switch was exploited to tune the bistable switching so small that noise induced switching occurs. In this regime, the time-dependent response to a weak external periodic signal was studied. The noise-activated switching of the junction was synchronized with the weak external periodic signal due to the presence of the sole internal noise. A maximum synchronization is found and interpreted in terms of stochastic resonance.
Static dielectric constant of Al nanocrystal/Al2O3 nanocomposite thin films determined by the capacitance-voltage reconstruction technique
Authors: Liu Z. , Chen T. P. , Liu Y. , Yang M. , Wong J. I. , Cen Z. H.
Published: May 2010

Al nanocrystal (nc-Al)/Al2O3 nanocomposite thin films were synthesized by radio-frequency magnetron sputtering. The static dielectric constant (εr) of the nanocomposite thin films was determined by the capacitance-voltage reconstruction technique which was able to correct for the influence of high current conduction in the thin films. In contrast to pure Al2O3, the nanocomposite has a much higher εr and its εr exhibits strong temperature dependence also. The higher εr is attributed to the dipole effect of the Al–O dangling bonds due to the presence of nc-Al in the Al2O3 matrix. However, the dipole effect degrades at a higher temperature, which explains the observed decrease in εr with increasing temperature.