bluuebunny/crossref_metadata_2025 huggingface dataset:
HOPF–CYCLIC HOMOLOGY AND RELATIVE CYCLIC HOMOLOGY OF HOPF–GALOIS EXTENSIONS
Authors: JARA P. , ŞTEFAN D.
Published: June 2006

Let $H$ be a Hopf algebra and let $\mathcal{M}_s (H)$ be the category of all left $H$-modules and right $H$-comodules satisfying appropriate compatibility relations. An object in $\mathcal{M}_s (H)$ will be called a stable anti-Yetter–Drinfeld module (over $H$) or a SAYD module, for short. To each $M \in \mathcal{M}_s (H)$ we associate, in a functorial way, a cyclic object $\mathrm{Z}_\ast (H, M)$. We show that our construction can be used to compute the cyclic homology of the underlying algebra structure of $H$ and the relative cyclic homology of $H$-Galois extensions.

Let $K$ be a Hopf subalgebra of $H$. For an arbitrary $M \in \mathcal{M}_s (K)$ we define a right $H$-comodule structure on $\mathrm{Ind}_K^H M := H \otimes_K M$ so that $\mathrm{Ind}_K^H M$ becomes an object in $\mathcal{M}_s (H)$. Under some assumptions on $K$ and $M$ we compute the cyclic homology of $\mathrm{Z}_\ast (H, \mathrm{Ind}_K^H M)$. As a direct application of this result, we describe the relative cyclic homology of strongly graded algebras. In particular, we calculate the cyclic homology of group algebras and quantum tori.

Finally, when $H$ is the enveloping algebra of a Lie algebra $\mathfrak{g}$, we construct a spectral sequence that converges to the cyclic homology of $H$ with coefficients in a given SAYD module $M$. We also show that the cyclic homology of almost symmetric algebras is isomorphic to the cyclic homology of $H$ with coefficients in a certain SAYD module.
Long-term passage of tachyzoites in tissue culture can attenuate virulence ofNeospora caninum in vivo
Authors: BARTLEY P. M. , WRIGHT S. , SALES J. , CHIANINI F. , BUXTON D. , INNES E. A.
Published: June 2006

To determine whether prolongedin vitropassage would result in attenuation of virulencein vivo,Neospora caninumtachyzoites were passaged for different lengths of timein vitroand compared for their ability to cause disease in mice. Groups of Balb/c mice were inoculated intraperitoneally with 5×106or 1×107of low-passage or high-passageN. caninumtachyzoites. The mice were monitored for changes in their demeanour and body weight, and were culled when severe clinical symptoms of murine neosporosis were observed. Mice inoculated with the high-passage parasites survived longer (P<0·05), and showed fewer clinical symptoms of murine neosporosis, compared to the mice receiving the low-passage parasites. The parasite was detected in the brains of inoculated mice using immunohistochemistry and ITS1 PCR. Tissue cysts containing parasites were seen in mice inoculated with both low-passage and high-passage parasites. When thein vitrogrowth rates of the parasites were compared, the high-passage parasites initially multiplied more rapidly (P<0·001) than the low-passage parasites, suggesting that the high-passage parasites had become more adapted to tissue culture. These results would suggest that it is possible to attenuate the virulence ofN. caninumtachyzoites in mice through prolongedin vitropassage.
A detailed comparison of WSD systems: an analysis of the system answers for the SENSEVAL-2 English all words task
Authors: PREISS JUDITA
Published: June 2006

We compare the word sense disambiguation systems submitted for the English-all-words task in SENSEVAL-2. We give several performance measures for the systems, and analyze correlations between system performance and word features. A decision tree learning algorithm is employed to discover the situations in which systems perform particularly well, and the resulting decision tree is examined. We investigate using a decision tree based on the SENSEVAL systems to (i) filter out senses unlikely to be correct, and to (ii) combine WSD systems. Some combinations created in this way outperform the best SENSEVAL system.
Thermosphere density response to the 20–21 November 2003 solar and geomagnetic storm from CHAMP and GRACE accelerometer data
Authors: Bruinsma Sean , Forbes Jeffrey M. , Nerem R. Steven , Zhang Xiaoli
Published: June 2006

Densities in the 400–500 km height region inferred from accelerometer measurements on the CHAMP and GRACE satellites are utilized to study the response to the isolated and severe geomagnetic storm of 20–21 November 2003. The CHAMP and GRACE satellites provide data at approximate local times of 1110/2310 and 1430/0230 hours, respectively. In a global sense, density increases of order 300–800% occur during this storm, with relatively little time delay at high latitudes and with about 4‐hour delay at the equator. Significant latitudinal asymmetries in the response are discussed in the context of neutral wind patterns and enhanced summer versus winter Joule heating rates at high latitudes. Comparisons with the NRLMSISE‐00 empirical model densities during this period show marked differences in amplitude of the response, as well as latitudinal and temporal structures. Evidence for a tight coupling between solar wind and neutral density variability is found for the high‐latitude summer hemisphere near noon, in that densities near 410 km are very responsive to increases in solar wind dynamic pressure, even during periods when both Bz and By are near zero or positive. Filtering of the data reveals regional‐scale (∼1000–2000 km) density anomalies that are common between the CHAMP and GRACE measurements. During the geomagnetic disturbance, alternating regions of density enhancements (∼50%) and depressions (∼50%) exist between the pole and low to middle latitudes that have the appearance of a standing wave pattern. During magnetically quiet intervals before and after the storm, daytime density depressions (∼4–8%) are seen that track the magnetic equator, while density enhancements (∼10%) track the latitudes of the ionospheric Appleton anomaly peaks. Large‐scale (≥1000 km) wave‐like structures are also prevalent during both day and night during the magnetic disturbance and extend throughout both hemispheres, consistent with the concept that these are associated with the so‐called “direct” gravity waves forced in the auroral regions and propagating far from the source. Substantial variability is also present at medium scales (∼300–500 km), but these structures are confined mainly to middle to high latitudes, in accord with theoretical expectations. GRACE‐A and GRACE‐B data are used in a feasibility study of the detection of small‐scale wave activity by taking advantage of the 30‐s separation of the satellites in the same orbital plane. Despite the large amount of maneuvers, which are not always recorded, this first analysis is promising. Amplitude variations of order 10–20% and wave speeds of 1000–1500 m s−1 are observed.
Relativistic electron scattering by electrostatic upper hybrid waves in the radiation belt
Authors: Shklyar D. R. , Kliem B.
Published: June 2006

Observations of particle precipitation into the Earth's atmosphere performed on low‐altitude satellites have excited substantial interest in relativistic electron precipitation bursts from the outer zone of the radiation belt. As underlying mechanism of such bursts, we suggest particle scattering into the loss cone due to higher‐order cyclotron resonance interaction between relativistic electrons and intense narrow‐band upper hybrid waves, which are frequently observed outside the plasmapause. The case of a single wave and the case of a wide wave number spectrum are considered, and approximate expressions for the relativistic particle diffusion coefficients in phase space are calculated for conditions of an inhomogeneous plasma. It is found that relativistic electrons have a preference over lower‐energy electrons from the viewpoint of the number of cyclotron resonances that a particle crosses during each bounce period. Owing to the predominantly longitudinal direction of the upper hybrid wave group velocity, the resonant wave‐particle interaction can take place over many electron bounce periods, which facilitates the particle scattering into the loss cone. The theory developed in the present paper accounts for two main features of the relativistic electron precipitation bursts, namely, a strong energy dependence in the electron precipitation process and the small‐scale burst structure, which is primarily attributed to the localization and strong inhomogeneity of the growth region of the upper hybrid modes responsible for the scattering. The existence of intrinsic temporal structure of the precipitation on timescales comparable to the bounce period is also consistent with the theory due to the high efficiency of the scattering process.
Medium‐scale traveling ionospheric disturbances affecting GPS measurements: Spatial and temporal analysis
Authors: Hernández‐Pajares M. , Juan J. M. , Sanz J.
Published: June 2006

In this work we present a simple technique to estimate the medium‐scale traveling ionospheric disturbances (MSTIDs) characteristics (such as occurrence, velocity, vertical propagation) with periods lower than 20 min and its application to a set of GPS data both temporally and spatially representative (near one solar cycle and four local networks in the Northern and Southern Hemispheres, respectively). Some of the main results presented in this paper are the MSTIDs which occur at daytime in local winter and nighttime in local summer, related to the solar terminator and modulated by the solar cycle. They present equatorward (from ∼100 to 400 m/s) and westward (∼50 to 200 m/s) horizontal propagation velocities, respectively. The corresponding periods are compatible (higher) with the theoretical prediction, which is given by the neutral atmosphere buoyancy period associated with the Brunt‐Väisälä frequency (about 600 s). Moreover, higher TIDs productivity is mainly associated with the downward vertical propagation. Finally, the results obtained in this study suggest the possibility of developing future MSTID models to mitigate its impact in applications like precise satellite navigation.
Globally synchronous ice core volcanic tracers and abrupt cooling during the last glacial period
Authors: Bay R. C. , Bramall N. E. , Price P. B. , Clow G. D. , Hawley R. L. , Udisti R. , Castellano E.
Published: June 2006

We perform a Monte Carlo pattern recognition analysis of the coincidence between three regional volcanic histories from ice coring of Greenland and Antarctica over the period 2 to 45 ka, using SO4 anomalies in Greenland and East Antarctica determined by continuous core chemistry, together with West Antarctic volcanic ash layers determined by remote optical borehole logging and core assays. We find that the Antarctic record of volcanism correlates with Glacial abrupt climate change at a 95% to >99.8% (∼3σ) significance level and that volcanic depositions at the three locations match at levels exceeding 3σ, likely indicating that many common horizons represent single eruptive events which dispersed material world wide. These globally coincident volcanics were associated with abrupt cooling, often simultaneous with onsets or sudden intensifications of millennial cold periods. The striking agreement between sites implies that the consistency of current timescales obtained by isotopic and glaciological dating methods is better than estimated.
Monthly averages of nitrous oxide and ozone for the Northern and Southern Hemisphere high latitudes: A “1‐year climatology” derived from ILAS/ILAS‐II observations
Authors: Khosrawi F. , Müller R. , Proffitt M. H. , Nakajima H.
Published: June 2006

Correlations of ozone (O3) and nitrous oxide (N2O) have been suggested as a tool for validating photochemical models and as a reference for estimating high‐latitude ozone loss. However, so far no analysis of ozone‐tracer relations is available that provides a good temporal coverage during all months. Here we combine measurements from the Improved Limb Atmospheric Spectrometers (ILAS/ILAS‐II) to derive an O3/N2O climatology for the high‐latitude regions in the Northern and Southern Hemisphere for each month of the year, thus providing a complete seasonal cycle. ILAS and ILAS‐II operated on board the Advanced Earth Observing Satellite (ADEOS/ADEOS‐II), and both instruments use the solar occultation technique. ILAS operated for 8 months in 1996/1997, and ILAS‐II operated for 7 months in 2003. The ILAS‐II measurements cover the months that are not available from ILAS. The ILAS/ILAS‐II correlations of ozone versus nitrous oxide are organized monthly in both hemispheres by partitioning these data into equal bins of altitude or potential temperature. The resulting families of curves allow separation of ozone changes due to photochemistry from those due to transport. The combined ILAS/ILAS‐II data set corroborates earlier findings that the families of O3/N2O curves are separated and generally do not cross and further that the separation is much clearer for the potential temperature binning than for the altitude binning. The much clearer separation for the potential temperature binning is due to transport being predominantly isentropic. Thus these curves are particularly suitable for the validation of photochemical models. The seasonal cycle of O3/N2O distributions in the Northern and Southern Hemisphere high latitudes is found to be rather different. In the Southern Hemisphere, O3/N2O distributions are influenced by the strong chemical ozone loss in the Antarctic vortex and by a much longer duration of the polar vortex. In the Northern Hemisphere, diabatic descent is much more pronounced. Solely during the setup phase of the polar vortex the N2O/O3 distributions in the two hemispheres are rather similar.
Validation of ILAS‐II version 1.4 O3, HNO3, and temperature data through comparison with ozonesonde, ground‐based FTS, and lidar measurements in Alaska
Authors: Yamamori Miho , Kagawa Akiko , Kasai Yasuko , Mizutani Kohei , Murayama Yasuhiro , Sugita Takafumi , Irie Hitoshi , Nakajima Hideaki
Published: June 2006

Version 1.4 data from the Improved Limb Atmospheric Spectrometer‐II (ILAS‐II) were validated through comparison with profile data measured by several instruments at Poker Flat (65.1°N, 147.5°W), Alaska. The height profiles of O3 and HNO3 provided by ILAS‐II were compared with those retrieved from spectra measured by a ground‐based Fourier transform infrared spectrometer (FTS). The O3 and HNO3 abundances measured by ILAS‐II and FTS in the 17–35 km altitude range agreed within the precision of the two measurements. The O3 volume mixing ratios measured by ILAS‐II above (below) 20 km were 10% lower (higher) than those from the FTS measurements. The HNO3 values from ILAS‐II and FTS agreed to within 10% above 17 km. The O3 profiles obtained from electrochemical concentration cell (ECC) ozonesondes launched from Fairbanks (64.8°N, 147.9°W) were also compared to ILAS‐II data. The ILAS‐II ozone abundance agreed with the ozonesonde values. Comparison of mesospheric and upper stratospheric temperature data obtained by ILAS‐II and Rayleigh lidar indicated that the temperature derived from ILAS‐II was significantly higher (lower) than that from lidar at about 60 (40) km.
Global tropospheric ozone modeling: Quantifying errors due to grid resolution
Authors: Wild Oliver , Prather Michael J.
Published: June 2006

Ozone production in global chemical models is dependent on model resolution because ozone chemistry is inherently nonlinear, the timescales for chemical production are short, and precursors are artificially distributed over the spatial scale of the model grid. In this study we examine the sensitivity of ozone, its precursors, and its production to resolution by running a global chemical transport model at four different resolutions between T21 (5.6° × 5.6°) and T106 (1.1° × 1.1°) and by quantifying the errors in regional and global budgets. The sensitivity to vertical mixing through the parameterization of boundary layer turbulence is also examined. We find less ozone production in the boundary layer at higher resolution, consistent with slower chemical production in polluted emission regions and greater export of precursors. Agreement with ozonesonde and aircraft measurements made during the NASA TRACE‐P campaign over the western Pacific in spring 2001 is consistently better at higher resolution. We demonstrate that the numerical errors in transport processes on a given resolution converge geometrically for a tracer at successively higher resolutions. The convergence in ozone production on progressing from T21 to T42, T63, and T106 resolution is likewise monotonic but indicates that there are still large errors at 120 km scales, suggesting that T106 resolution is too coarse to resolve regional ozone production. Diagnosing the ozone production and precursor transport that follow a short pulse of emissions over east Asia in springtime allows us to quantify the impacts of resolution on both regional and global ozone. Production close to continental emission regions is overestimated by 27% at T21 resolution, by 13% at T42 resolution, and by 5% at T106 resolution. However, subsequent ozone production in the free troposphere is not greatly affected. We find that the export of short‐lived precursors such as NOx by convection is overestimated at coarse resolution.
Prototypical solitons in the South China Sea
Authors: Klymak Jody M. , Pinkel Robert , Liu Cho‐Teng , Liu Antony K. , David Laura
Published: June 2006

Surface signatures associated with non‐linear internal waves are often seen in satellite images of the western South China Sea (SCS) slope and shelf. Observation in the deep sea, to the east, are rare. Here we report on the evolution of an energetic packet as it propagated through the deep central basin of the SCS, toward the western slope and shelf. The waves have amplitudes estimated at 170 m, half widths of 3 km, and phase speeds of 2.9 ± 0.1 m/s, faster than the mode‐1 linear phase speed of 2.6 m/s. The shape and observed phase speed were consistent with the Korteweg‐deVries (KdV) model over the 65‐km path that they were tracked. The intrinsic velocity shear of the waves is small compared to pre‐existing shears, and the waves exhibit weak turbulence. The KdV fit and a satellite‐derived estimate of horizontal wave extent imply a westward energy flux of 4.5 GW for each crest.
IUPAC-NIST Solubility Data Series. 81. Hydrocarbons with Water and Seawater—Revised and Updated. Part 11. C13–C36 Hydrocarbons with Water
Authors: Shaw David G. , Maczynski Andrzej , Goral Marian , Wisniewska-Goclowska Barbara , Skrzecz Adam , Owczarek Iwona , Blazej Krystyna , Haulait-Pirson Marie-Claire , Hefter Glenn T. , Kapuku F. , Maczynska Zofia , Szafranski Andrzej
Published: June 2006

The mutual solubilities and related liquid–liquid equilibria of C13–C36 hydrocarbons with water are exhaustively and critically reviewed. Reports of experimental determination of solubility in 56 chemically distinct binary systems that appeared in the primary literature prior to end of 2002 are compiled. For 17 systems sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Data Series, a new method based on the evaluation of all the experimental data for a given homologous series of aliphatic and aromatic hydrocarbons was used.
A Reference Multiparameter Viscosity Equation for R134a with an Optimized Functional Form
Authors: Scalabrin G. , Marchi P. , Span R.
Published: June 2006

An optimization technique was applied to develop a functional form for a multiparameter viscosity equation η=η(ρ,T) for R134a. The results obtained are very promising, with an average absolute deviation of 0.55% for the currently available 549 primary data points. Compared to viscosity equations available in the literature, this is a significant improvement. Advantages become evident especially at gaseous states. As usual, both the development and the use of the viscosity equation require a highly accurate equation of state in order to convert the independent variables used for the experimental data and in most applications, (P,T), into the independent variables of the viscosity equation, (ρ,T). Though the equation was developed directly using the available data, the zero-density viscosity and the reduced second viscosity virial coefficient are correctly reproduced in the data range. The technique used to develop the equation, which is heuristic and not theoretically founded, is capable of selecting consistent data sets and thus is a powerful tool for screening the available experimental data. For the viscosity surface representation of a pure fluid this study shows that the limit in the achievement of a better accuracy is much more due to the present experimental uncertainty level for this property rather than to the effectiveness of the proposed modeling method.
A New Equation of State for H2O Ice Ih
Authors: Feistel Rainer , Wagner Wolfgang
Published: June 2006

Various thermodynamic equilibrium properties of naturally abundant, hexagonal ice (ice Ih) of water (H2O) have been used to develop a Gibbs energy function g(T,p) of temperature and pressure, covering the ranges 0–273.16 K and 0 Pa–210 MPa, expressed in the temperature scale ITS-90. It serves as a fundamental equation from which additional properties are obtained as partial derivatives by thermodynamic rules. Extending previously developed Gibbs functions, it covers the entire existence region of ice Ih in the T-p diagram. Close to zero temperature, it obeys the theoretical cubic limiting law of Debye for heat capacity and Pauling’s residual entropy. It is based on a significantly enlarged experimental data set compared to its predecessors. Due to the inherent thermodynamic cross relations, the formulas for particular quantities like density, thermal expansion, or compressibility are thus fully consistent with each other, are more reliable now, and extended in their ranges of validity. In conjunction with the IAPWS-95 formulation for the fluid phases of water, the new chemical potential of ice allows an alternative computation of the melting and sublimation curves, being improved especially near the triple point, and valid down to 130 K sublimation temperature. It provides an absolute entropy reference value for liquid water at the triple point.
Ion induced lamellar-lamellar phase transition in charged surfactant systems
Authors: Harries Daniel , Podgornik Rudi , Parsegian V. Adrian , Mar-Or Etay , Andelman David
Published: June 2006

We propose a model for the liquid-liquid (Lα→Lα′) phase transition observed in osmotic pressure measurements of certain charged lamellae-forming amphiphiles. The model free energy combines mean-field electrostatic and phenomenological nonelectrostatic interactions, while the number of dissociated counterions is treated as a variable degree of freedom that is determined self-consistently. The model, therefore, joins two well-known theories: the Poisson-Boltzmann theory for ionic solutions between charged lamellae and the Langmuir-Frumkin-Davies adsorption isotherm modified to account for charged adsorbing species. Minimizing the appropriate free energy for each interlamellar spacing, we find the ionic density profiles and the resulting osmotic pressure. While in the simple Poisson-Boltzmann theory the osmotic pressure isotherms are always smooth, we observe a discontinuous liquid-liquid phase transition when the Poisson-Boltzmann theory is self-consistently augmented by the Langmuir-Frumkin-Davies adsorption. This phase transition depends on the area per amphiphilic head group, as well as on nonelectrostatic interactions of the counterions with the lamellae and interactions between counterion-bound and counterion-dissociated surfactants. Coupling the lateral phase transition in the bilayer plane with electrostatic interactions in the bulk, our results offer a qualitative explanation for the existence of the Lα→Lα′ phase transition of didodecyldimethylammonium bromide (DDABr), but the transition's apparent absence for the chloride and the iodide homologs. More quantitative comparisons with experiment require better understanding of the microscopic basis of the phenomenological model parameters.
Photoionization of Li and Na in Debye plasma environments
Authors: Sahoo Satyabrata , Ho Y. K.
Published: June 2006

A calculation of the photoionization cross sections is presented for alkali-metal atoms such as Li and Na in plasma environments. The computational scheme is based on the complex coordinate rotation method. A model potential formalism has been used to simplify the computational complexity of the problems of making quantitative predictions of properties and interactions of many electron systems in Debye plasmas. The plasma environment is found to appreciably influence the photoionization cross sections. In this regard the photoionization cross sections of isolated atoms are also discussed that is found to be in good agreement with the previous theoretical results. It is observed that the strong plasma screening effect remarkably alters the photoionization cross sections near the ionization threshold. The Cooper minimum in the photoionization cross sections of Na shifts toward the higher energy as the plasma screening effect increases. For Li, the Cooper minimum is uncovered in strong plasma environments. This is the first time such structures have been determined.
The carrier gas pressure effect in a laminar flow diffusion chamber, homogeneous nucleation of n-butanol in helium
Authors: Hyvärinen Antti-Pekka , Brus David , Ždímal Vladimír , Smolík Jiři , Kulmala Markku , Viisanen Yrjö , Lihavainen Heikki
Published: June 2006

Homogeneous nucleation rate isotherms of n-butanol+helium were measured in a laminar flow diffusion chamber at total pressures ranging from 50to210kPa to investigate the effect of carrier gas pressure on nucleation. Nucleation temperatures ranged from 265to280K and the measured nucleation rates were between 102 and 106cm−3s−1. The measured nucleation rates decreased as a function of increasing pressure. The pressure effect was strongest at pressures below 100kPa. This negative carrier gas effect was also temperature dependent. At nucleation temperature of 280K and at the same saturation ratio, the maximum deviation between nucleation rates measured at 50 and 210kPa was about three orders of magnitude. At nucleation temperature of 265K, the effect was negligible. Qualitatively the results resemble those measured in a thermal diffusion cloud chamber. Also the slopes of the isothermal nucleation rates as a function of saturation ratio were different as a function of total pressure, 50kPa isotherms yielded the steepest slopes, and 210kPa isotherms the shallowest slopes. Several sources of inaccuracies were considered in the interpretation of the results: uncertainties in the transport properties, nonideal behavior of the vapor-carrier gas mixture, and shortcomings of the used mathematical model. Operation characteristics of the laminar flow diffusion chamber at both under-and overpressure were determined to verify a correct and stable operation of the device. We conclude that a negative carrier gas pressure effect is seen in the laminar flow diffusion chamber and it cannot be totally explained with the aforementioned reasons.
Auxiliary-field quantum Monte Carlo calculations of molecular systems with a Gaussian basis
Authors: Al-Saidi W. A. , Zhang Shiwei , Krakauer Henry
Published: June 2006

We extend the recently introduced phaseless auxiliary-field quantum Monte Carlo (QMC) approach to any single-particle basis and apply it to molecular systems with Gaussian basis sets. QMC methods in general scale favorably with the system size as a low power. A QMC approach with auxiliary fields, in principle, allows an exact solution of the Schrödinger equation in the chosen basis. However, the well-known sign/phase problem causes the statistical noise to increase exponentially. The phaseless method controls this problem by constraining the paths in the auxiliary-field path integrals with an approximate phase condition that depends on a trial wave function. In the present calculations, the trial wave function is a single Slater determinant from a Hartree-Fock calculation. The calculated all-electron total energies show typical systematic errors of no more than a few millihartrees compared to exact results. At equilibrium geometries in the molecules we studied, this accuracy is roughly comparable to that of coupled cluster with single and double excitations and with noniterative triples [CCSD(T)]. For stretched bonds in H2O, our method exhibits a better overall accuracy and a more uniform behavior than CCSD(T).
Experiments with microrods in a radio-frequency plasma sheath
Authors: Marcus L. R. , Annaratone B. M. , Thomas H. M. , Morfill G. E.
Published: June 2006

This paper presents an experimental analysis of the behavior of elongated particles suspended in an rf-enhanced plasma sheath and subjected to different forces. The linear motion of the particles through the chamber was tracked, and the forces acting on the particles were analyzed. Two different experiments shall be presented here, involving the balance of the Lorentz force or the electrostatic force with the neutral drag force on the microrods. In both experiments, the sheath electric field, charging of the particles, floating potential, as well as many other factors, were used to quantify the forces and interpret the experiments.
Theoretical characterization of dihydrogen adducts with halide anions
Authors: Vitillo Jenny G. , Damin Alessandro , Zecchina Adriano , Ricchiardi Gabriele
Published: June 2006

The interaction between a hydrogen molecule and the halide anions F−, Cl−, Br−, and I− has been studied at different levels of theory and with different basis sets. The most stable configurations of the complexes have a linear geometry, while the t-shaped complexes are saddle points on the potential energy surface, opposite to what is observed for alkali cations. An electrostatic analysis conducted on the resulting adducts has highlighted the predominance of the electrostatic term in the complexation energy and, in particular, of the quadrupole- and dipole-polarizability dependent contributions. Another striking difference with respect to the positive ions, is the fact that although the binding energies have similar values (ranging between 25 and 3kJ∕mol for F− and I−, respectively), the vibrational shift of the ν̃H–H and in general the perturbation of the hydrogen molecule in complexes are much greater in the complexes with anions (Δν̃H–H ranges between −720 and −65cm−1). Another difference with respect to the interaction with cations is a larger charge transfer from the anion to the hydrogen molecule. The Δν̃ is the result of the cooperative role of the electrostatics and of the charge transfer in the interaction. The correlation between binding energies and vibrational shift is far from linear, contrary to what is observed for cation complexes, in accordance with the higher polarizability and dynamic polarizability of the molecule along the molecular axis. The observed correlation may be valuable in the interpretation of spectra and thermodynamic properties of adsorbed H2 in storage materials.
Mass detection sensitivity of piezoelectric cantilevers with a nonpiezoelectric extension
Authors: Shen Zuyan , Shih Wan Y. , Shih Wei-Heng
Published: June 2006

A piezoelectric cantilever (PEC) is a transverse transducer consisting of a piezoelectric layer, e.g., lead zirconate titanate (PZT), bonded to a nonpiezoelectric layer, e.g., stainless steel, which has a uniform cross section throughout the length. A PEC with a thin nonpiezoelectric extension, on the other hand, has two distinctive sections each with its own thickness and transverse mass-density and elastic-modulus profiles. A piezoelectric cantilever with a nonpiezoelectric extension has been increasingly used as an in situ biosensor that has the advantage of dipping only the nonpiezoelectric extension part in an aqueous solution without electrically insulating the piezoelectric section. In this study, we examined both experimentally and theoretically the effect of the thin nonpiezoelectric extension, in particular, its length ratio to the piezoelectric part on the vibration wave form and mass detection sensitivity of a PEC. We showed that the nonpiezoelectric extension caused substantial distortion to the vibration wave form. Due to the wave form distortion, the mass detection sensitivity of a PEC with a nonpiezoelectric extension can be higher than that of a PEC of the same length without a nonpiezoelectric extension. Using PECs consisting of a 0.25mm thick PZT layer and a 0.07mm thick stainless steel of various lengths, l1, and a 0.07mm thick nonpiezoelectric stainless steel extension of various lengths, l2, we showed that for any l1, the maximum mass detection sensitivities of first, second, and third modes occurred at l2∕l1=0.6, 0.28, and 0.16 and the maximum values were, respectively, 1.42, 3.9, and 6.7 times the mass detection sensitivity of a PEC of the same l1 without a nonpiezoelectric extension.
Dynamic angle-scanning reflectometer device
Authors: García-Valenzuela A. , Sandoval-Romero G. E. , Sánchez-Pérez C. , Castañeda L. , Guadarrama-Santana A.
Published: June 2006

This article describes a simple and fast angle-scanning reflectometer. Approximate formulas for the design and implementation of this type of reflectometer are provided. An experimental device was assembled and its performance was evaluated. The instrument scans the angle of incidence of a laser beam in a range of 5°–10° in less than 0.2ms. The reflectance equivalent noise of our experimental device was about 0.005. The instrument is suitable to measure the coherent reflectance versus the angle of incidence from light diffusing samples.
Dissipative trapped-electron instability in quasihelically symmetric stellarators
Authors: Rafiq T. , Hegna C. C.
Published: June 2006

The linear electrostatic dissipative trapped-electron mode is investigated in a quasihelically symmetric (QHS) stellarator and a configuration whose symmetry is spoiled by the addition of a mirror contribution to the magnetic spectrum. The effect of the trapped electrons is accounted for using the drift kinetic equation with an energy-dependent Krook collision operator and an effective collision frequency giving the rate of detrapping. The ballooning mode formalism and Wentzel-Kramers-Brillouin type boundary conditions are used to solve an eigenvalue problem for a drift wave equation with nearly adiabatic electrons in a fully three-dimensional magnetohydrodynamic equilibria. The trapped-electron growth rate is calulated using a perturbative approach. Multiple classes of helically localized and toroidally localized eigenfunctions in the ballooning space are calculated. The results of the QHS configuration is compared and contrasted with the results of the mirror configuration. The helically trapped modes are found to be most destabilizing. In both configurations the magnitude of the linear growth rates are comparable, crudely indicating the same level of anomalous flux as has also been observed in the edge region of experiments.
Temperature control device for single molecule measurements using the atomic force microscope
Authors: Yang Yao , Lin Fan-Chi , Yang Guoliang
Published: June 2006

The design and implementation of a temperature control device for the atomic force microscope (AFM) are described. This device is based on a thermoelectric module which can be used for both heating and cooling the samples in the AFM liquid chamber within the range of 5–50°C. A thermocouple is inserted in the liquid chamber to measure the sample temperature. A commercial thermoelectric temperature controller is used to keep the temperature constant during a measurement, which can be stabilized within 0.1°C. To dissipate the heat generated by the thermoelectric module during cooling, a water cooled heat sink is used. Using this device, imaging and mechanical unfolding experiments were carried out at different temperatures. The results show that the temperature control device does not significantly reduce the imaging capacities of the AFM, and that the force-induced unfolding of individual protein molecules can be readily observed at different temperatures. Temperature dependent single molecule measurements can broaden the applications of AFM and reveal new insights into the macromolecular structures and processes.
Scanning near-field optical microscope working with a CdSe∕ZnS quantum dot based optical detector
Authors: Aigouy L. , Samson B. , Julié G. , Mathet V. , Lequeux N. , Nì. Allen C. , Diaf H. , Dubertret B.
Published: June 2006

We have developed a scanning near-field optical microscope that uses a subwavelength-sized silica sphere covered with CdSe∕ZnS quantum dots as a fluorescent optical detector. Due to the good photostability of these semiconducting particles, we are routinely able to perform several successive scans without a noticeable decrease of fluorescence signals. As an example, we will show some images of the light immediately transmitted through 300nm wide slits made in a thin gold film. We will also discuss the advantages of such fluorescent probes compared to other near-field optical techniques.
Toroidal and poloidal flows in single-fluid and two-fluid tokamak equilibria
Authors: Thyagaraja A. , McClements K. G.
Published: June 2006

Toroidal flow velocities of the order of the local sound speed and poloidal flows exceeding theoretical predictions have been observed in several tokamaks. Steady toroidal and poloidal flow effects are studied using dissipationless single-fluid and two-fluid theory, with electron inertia neglected in the latter case. An exact analytic treatment of the two-fluid system, with the electron and ion temperatures both assumed to be flux functions and ion poloidal flows neglected, reveals a much wider class of rotation profiles than those corresponding to rigid body rotation of flux surfaces, which is required by ideal magnetohydrodynamics (MHD). A generalized expression is obtained for the variation of the density on a flux surface in the presence of flows, and a relation is established between the rotation and temperature profiles that makes it possible to test experimentally the assumption of rigid body rotation. Relaxing the assumption that ion temperature is a flux function leads to a still wider class of possible profiles. It is shown that ion momentum balance in the absence of ion poloidal flows implies a Grad-Shafranov equation that is structurally similar to the standard ideal MHD form of this equation. Leading order ion poloidal flow corrections to the Grad-Shafranov equation are also computed.
On the use of critical gradient models in fusion plasma transport studies
Authors: Carreras B. A. , Lynch V. E. , van Milligen B. Ph. , Sánchez R.
Published: June 2006

Transport models for tokamak devices are often based on transport coefficients involving a critical threshold condition. In this paper, it is argued that the validation of such models against experimental data requires special care when the system profiles are close to this threshold (at some locations), due to the contribution of fluctuations to transport. The arguments presented here could have implications for the understanding and modeling of heat transport in tokamaks, since the large stiffness of the temperature profile observed in experimental points to a near-critical situation over much of the radius. The difficulties are illustrated by means of a simplified transport model, and a possible way to ameliorate this issue is proposed.
Theoretical study of valence photoelectron spectra of Re(CO)5X (X=Cl, Br, and I): A spin-orbit DK3 symmetry-adapted cluster/symmetry-adapted cluster-configuration interaction study
Authors: Nakajima Takahito , Hane Shintaro , Hirao Kimihiko
Published: June 2006

The valence photoelectron spectra of Re(CO)5X (X=Cl, Br, and I) are studied theoretically using symmetry-adapted cluster (SAC)/SAC-configuration interaction (SAC-CI) theory. The relativistic effects are included by the third-order Douglas-Kroll (DK3) method, and the spin-orbit coupling is also considered. Both electron correlation and relativistic effects are significant in assigning the valence photoelectron spectra of Re(CO)5X (X=Cl, Br, and I). DK3-SAC/SAC-CI provides values for the relative peak positions in a reasonable agreement with the observed photoelectron spectra. The sequence of ionization energies for Re(CO)5Cl, Re(CO)5Br, and Re(CO)5I are calculated as e′[a1(Cl)]>e′[e(Re+Cl)]≈e″[e(Re+Cl)]>e″[b2(Re)]>e′[e(Re–Cl)]>e″[e(Re–Cl)], e′[a1(Br)]>e′[e(Re+Br)]>e″[e(Re+Br)+b2(Re)]>e″[b2(Re)+e(Re+Br)]>e′[e(Re–Br)]>e″[e(Re–Br)], and e′[e(Re+I)+a1(I)]>e″[b2(Re)+e(Re+I)]≈e′[a1(I)+e(Re+I)]>e″[e(Re+I)+b2(Re)]>e′[e(Re–I)]>e″[e(Re–I)], respectively. These assignments are quite new and different from previous assignments.
Is E112 a relatively inert element? Benchmark relativistic correlation study of spectroscopic constants in E112H and its cation
Authors: Mosyagin N. S. , Isaev T. A. , Titov A. V.
Published: June 2006

We report the first results of relativistic correlation calculation of the spectroscopic properties for the ground state of E112H and its cation in which spin-orbit interaction is taken into account non-perturbatively. Studying the properties of E112 (eka-Hg) is required for chemical identification of its long-lived isotope, 112283. It is shown that appropriate accounting for spin-orbit effects leads to dramatic impact on the properties of E112H whereas they are not so important for E112H+. The calculated equilibrium distance, Recalc=1.662Å, in E112H is notably smaller than Reexpt=(1.738±0.003)Å and Recalc=1.738Å in HgH, whereas the dissociation energy, Decalc=0.42eV, in E112H is close to Deexpt=0.46eV and Decalc=0.41eV in HgH. These data are quite different from ReNH=1.829Å and DeNH=0.06eV obtained for E112H within the scalar-relativistic Douglas-Kroll approximation [Nakajima and Hirao, Chem. Phys. Lett. 329, 511 (2000)]. Our results indicate that E112 should not be expected to behave like a noble gas in contrast to the results by other authors.
Identification of bifunctional Δ12/ω3 fatty acid desaturases for improving the ratio of ω3 to ω6 fatty acids in microbes and plants
Authors: Damude Howard G. , Zhang Hongxiang , Farrall Leonard , Ripp Kevin G. , Tomb Jean-Francois , Hollerbach Dieter , Yadav Narendra S.
Published: June 2006

We report the identification of bifunctional Δ12/ω3 desaturases from
Fusarium moniliforme
,
Fusarium graminearum
, and
Magnaporthe grisea
. The bifunctional activity of these desaturases distinguishes them from all known Δ12 or ω3 fatty acid desaturases. The ω3 desaturase activity of these enzymes also shows a broad ω6 fatty acid substrate specificity by their ability to convert linoleic acid (LA), γ-linolenic acid, di-homo-γ-linolenic acid, and arachidonic acid to the ω3 fatty acids, α-linolenic acid (ALA), stearidonic acid, eicosatetraenoic acid, and eicosapentaenoic acid (EPA), respectively. Phylogenetic analysis suggests that ω3 desaturases arose by independent gene duplication events from a Δ12 desaturase ancestor. Expression of
F. moniliforme
Δ12/ω3 desaturase resulted in high ALA content in both
Yarrowia lipolytica
, an oleaginous yeast naturally deficient in ω3 desaturation, and soybean. In soybean, seed-specific expression resulted in 70.9 weight percent of total fatty acid (%TFA) ALA in a transformed seed compared with 10.9%TFA in a null segregant seed and 53.2%TFA in the current best source of ALA, linseed oil. The ALA/LA ratio in transformed seed was 22.3, a 110- and 7-fold improvement over the null segregant seed and linseed oil, respectively. Thus, these desaturases have potential for producing nutritionally desirable ω3 long-chain polyunsaturated fatty acids, such as EPA, with a significantly improved ratio of ω3/ω6 long-chain polyunsaturated fatty acids in both oilseeds and oleaginous microbes.
Stratum corneum cytokines and skin irritation response to sodium lauryl sulfate
Authors: De Jongh Cindy M. , Verberk Maarten M. , Withagen Carien E. T. , Jacobs John J. L. , Rustemeyer Thomas , Kezic Sanja
Published: June 2006

Little is known about cytokines involved in chronic irritant contact dermatitis. Individual cytokine profiles might explain at least part of the differences in the individual response to irritation. Our objective was to investigate the relation between baseline stratum corneum (SC) cytokine levels and the skin response to a single and a repeated irritation test. This study also aimed to determine changes in SC cytokine levels after repeated irritation. Transepidermal water loss (TEWL) and erythema were measured in 20 volunteers after single 24‐hr exposure to 1% sodium lauryl sulfate (SLS), and during and after repeated exposure to 0.1% SLS over a 3‐week period. SC cytokine levels were measured from an unexposed skin site and from the repeatedly exposed site. Interleukin (IL)‐1α decreased by 30% after repeated exposure, while IL‐1RA increased 10‐fold and IL‐8 increased fourfold. Baseline IL‐1RA and IL‐8 values were predictors of TEWL and erythema after single exposure (r = 0.55–0.61). 6 subjects showed barrier recovery during repeated exposure. Baseline IL‐1RA and IL‐8 levels are likely to be indicators of higher skin irritability after single exposure to SLS. Barrier repair in some of the subjects might explain the lack of agreement between the TEWL response after single and repeated irritation.
Understanding Psychopathology
Authors: Krueger Robert F. , Markon Kristian E.
Published: June 2006

Research on psychopathology is at a historical crossroads. New technologies offer the promise of lasting advances in our understanding of the causes of human psychological suffering. Making the best use of these technologies, however, requires an empirically accurate model of psychopathology. Much current research is framed by the model of psychopathology portrayed in current versions of the Diagnostic and Statistical Manual of Mental Disorders ( DSM; American Psychiatric Association, 2000 ). Although the modern DSMs have been fundamental in advancing psychopathology research, recent research also challenges some assumptions made in the DSM—for example, the assumption that all forms of psychopathology are well conceived of as discrete categories. Psychological science has a critical role to play in working through the implications of this research and the challenges it presents. In particular, behavior-genetic, personality, and quantitative-psychological research perspectives can be melded to inform the development of an empirically based model of psychopathology that would constitute an evolution of the DSM.
Therapeutic potential of RNA interference against cancer
Authors: Takeshita Fumitaka , Ochiya Takahiro
Published: June 2006

One of the most dramatic events of the past 5 years in the field of molecular biology has been the discovery of RNA interference (RNAi). Although RNAi is an evolutionarily conserved phenomenon for sequence‐specific gene silencing in mammalian cells, exogenous small interfering RNA (siRNA) and vector‐based short hairpin RNA (shRNA) can also invoke RNAi responses. Both are now not only experimental tools for analyzing gene function but are expected to be excellent avenues for drug target discovery and the emerging class of gene medicine for targeting incurable diseases such as cancer. The success of cancer therapeutic use of RNAi relies on the development of safe and efficacious delivery systems that introduce siRNA and shRNA expression vectors into target tumor cells. For their delivery, a variety of strategies have been used, most of them based on traditional gene therapy delivery systems. In this review, we present siRNA delivery method strategies and discuss the potential of RNAi‐based gene therapy in cancer treatment. (Cancer Sci 2006; 97: 689–696)