bluuebunny/crossref_metadata_2025 huggingface dataset:
Detailed characterization of plasma wave behavior using collective Thomson scattering (invited)
Authors: Montgomery D. S. , Kline J. L. , Tierney T. E.
Published: October 2004

Collective Thomson scattering is widely used to measure bulk plasma parameters in high density, laser-produced plasmas, and is used to detect plasma waves from instabilities. However, inhomogeneity in these small plasmas often leads to a spectrum with insufficient resolution to discern phenomena such as wave damping and nonlinear wave effects. Two techniques are discussed for laser-produced plasmas to overcome these limitations, and provide details of wave damping and nonlinear behavior. First, imaging Thomson scattering is used to obtain spatially resolved plasma wave profiles in a 100–200 eV plasma, and allows us to infer ion-ion collisional damping rates. Second, a diffraction-limited laser beam is used to drive stimulated Raman scattering in a hot plasma, generating large amplitude Langmuir waves. The comparatively small interaction volume permits sufficient spectral resolution to observe nonlinear wave behavior previously unresolved in other experiments.
Two-dimensional electron cyclotron emission imaging diagnostic for TEXTOR
Authors: Wang J. , Domier C. W. , Xia Z. G. , Liang Y. , Luhmann N. C. , Park H. , Munsat T. , Mazzucato E. , van de Pol M. J. , Classen I. G. J. , Donné A. J. H.
Published: October 2004

A two-dimensional electron cyclotron emission imaging (ECEI) diagnostic has been developed in which broad bandwidth radiation is collected by a vertically aligned mixer array and separated by frequency band. Using a 16 element array, and an 8 band receiver attached to each array element, time-resolved 16×8 images of electron temperature profiles and fluctuations of the TEXTOR plasma are acquired with vertical and horizontal channel spacings of 11 and 8 mm, and spot sizes of 13 and 9 mm, respectively. The system is wideband tunable from 95 to 130 GHz, and the focus location may be shifted horizontally via translation of one of the optical imaging elements. System design and laboratory testing details of the ECE Imaging optics and multichannel wideband electronics are presented, together with TEXTOR plasma data.
Hamilton-Jacobi equation for the least-action/least-time dynamical path based on fast marching method
Authors: Dey Bijoy K. , Janicki Marek R. , Ayers Paul W.
Published: October 2004

Classical dynamics can be described with Newton’s equation of motion or, totally equivalently, using the Hamilton-Jacobi equation. Here, the possibility of using the Hamilton-Jacobi equation to describe chemical reaction dynamics is explored. This requires an efficient computational approach for constructing the physically and chemically relevant solutions to the Hamilton-Jacobi equation; here we solve Hamilton-Jacobi equations on a Cartesian grid using Sethian’s fast marching method [J. A. Sethian, Proc. Natl. Acad. Sci. USA 93, 1591 (1996)]. Using this method, we can—starting from an arbitrary initial conformation—find reaction paths that minimize the action or the time. The method is demonstrated by computing the mechanism for two different systems: a model system with four different stationary configurations and the H+H2→H2+H reaction. Least-time paths (termed brachistochrones in classical mechanics) seem to be a suitable chioce for the reaction coordinate, allowing one to determine the key intermediates and final product of a chemical reaction. For conservative systems the Hamilton-Jacobi equation does not depend on the time, so this approach may be useful for simulating systems where important motions occur on a variety of different time scales.
Global potential energy surfaces for the Al+(1S)+H2 system
Authors: Salazar Michael R.
Published: October 2004

Global, three-dimensional multireference ab initio potential energy surfaces have been calculated for the AlH2+ system for the two lowest energy singlet states and the lowest energy triplet state. These surfaces were calculated using the multireference configuration interaction level of theory with a large basis set. The accuracy of the surfaces were checked against available experimental data and previous theoretical investigations. The areas of surface crossings between the ground state singlet surface and the lowest energy triplet surface and the first excited singlet surface have been thoroughly investigated in all three dimensions and found to give rise to two regions of surface crossings—an “early” crossing (reduced H2 distance) and a “late” crossing (enlarged H2 distance). It is anticipated that both of these crossings will be important in modeling the dynamics of the system. Each of the global potential energy surfaces were fit by interpolation methodology to obtain analytic representations of the surfaces. A representative classical simulation on the ground state singlet surface was performed and discussed.
Self-diffusion of rodlike and spherical particles in a matrix of charged colloidal spheres: A comparison between fluorescence recovery after photobleaching and fluorescence correlation spectroscopy
Authors: Lellig C. , Wagner J. , Hempelmann R. , Keller S. , Lumma D. , Härtl W.
Published: October 2004

The fluorescence recovery after photobleaching (FRAP) method and the fluorescence correlation spectroscopy (FCS) have been applied on suspensions of highly charged colloidal spheres with a small content of rod-shaped tobacco mosaic virus (TMV) particles. Since these methods only determine the self-diffusion coefficient of the fluorescently labeled species, DS of the rods and the spheres could independently be measured. The ionic strength of the dispersion medium has been varied to measure self-diffusion of rods and spheres in dependence on the degree of order of the matrix spheres. In contrast to FRAP, which allows the determination of the long-time self-diffusion coefficient DSL, FCS measures self-diffusion on a shorter time scale. Thus a comparison of the results that were obtained by FCS and FRAP, in combination with Brownian Dynamics simulations, gives insight into the time dependence of the self-diffusion coefficient of an interacting colloidal system. As the mean interparticle distance of the matrix is of the same order of magnitude as the length of a TMV rod, the rotational motion is influenced by the assembly of spheres around a TMV particle. Since FCS is sensitive both to translational and rotational motion, whereas FRAP, which probes the diffusion at much larger length scales, is only sensitive to the translational motion of TMV, the comparison of diffusion coefficients measured employing FRAP and FCS can give some insights in the rotational diffusion: the experimental data indicate a slowing down of the rotational motion of a TMV rod with increasing structural order of the matrix spheres.
The role of the reaction force to characterize local specific interactions that activate the intramolecular proton transfers in DNA basis
Authors: Herrera Bárbara , Toro-Labbe Alejandro
Published: October 2004

MP2/6-311G** and B3LYP/6-311G** studies of the intramolecular proton transfer in adenine, cytosine, guanine, and thymine has been performed, with the aim of evaluating the role of the reaction force as a global descriptor of the process. It turns out that the reaction force profile is quite an interesting tool to characterize reaction mechanisms. Indeed, in adenine and cytosine the proton transfer is assisted by an increasing electronic delocalization in the adjacent ring, whereas in guanine and thymine the attractive electrostatic interaction with the acceptor oxygen atom is strong enough to promote the transfer.
Full configuration interaction calculation of singlet excited states of Be3
Authors: Junquera-Hernández José Miguel , Sánchez-Marı́n José , Bendazzoli Gian Luigi , Evangelisti Stefano
Published: October 2004

The full configuration interaction (FCI) study of the singlets vertical spectrum of the neutral beryllium trimer has been performed using atomic natural orbitals [3s2p1d] basis set. The FCI triangular equilibrium structure of the ground state has been used to calculate the FCI vertical excitation energies up to 4.8 eV. The FCI vertical ionization potential for the same geometry and basis set amounts to 7.6292 eV. The FCI dipole and quadrupole transition moments from the ground state are reported as well. The FCI electric quadrupole moment of the X 3A1′ ground state has been also calculated with the same basis set (Θzz=−2.6461 a.u., Θxx=Θyy=−1/2Θzz). Twelve of the 19 calculated excited singlets are doubly excited states. Most of the states have large multiconfigurational character. These results provide benchmark values for electronic correlation multireference methods. (4e×6MO)CAS-SDCI values for the same energies and properties are also reported.
Thermodynamic behaviors of polyampholytes at low temperatures
Authors: Xu Beisi , Huang Lei , Liang Haojun
Published: October 2004

The thermodynamic properties of 6-mer polyampholyte chains were simulated with the multicanonical Monte Carlo method in a three-dimensional off-lattice model. The results demonstrate that the number of the charged monomers on the chain and the sequence significantly affect the transition behaviors of polyampholyte chains. In the case of the random distribution of the charged monomers, two oppositely charged monomers act as two stickers during a collapse process, due to which the movement of monomers is suppressed and the chains can more directly reach their solid state. Interestingly, in a proper arrangement of the charged monomers, the chains may have a proteinlike nondegenerate state, i.e., the chain is designable. The transition of such polyampholyte chains appears to be of a two-state, all-or-none type.
Reactions of N+, N2+, and N3+ with NO from 300 to 1400 K
Authors: Midey Anthony J. , Miller Thomas M. , Viggiano A. A.
Published: October 2004

Rate constants have been measured from 300 to 1400 K in a selected ion flow tube (SIFT) and a high temperature flowing afterglow for the reactions of N+, N2+ and N3+ with NO. In all of the systems, the rate constants are substantially less than the collision rate constant. Comparing the high temperature results to kinetics studies as a function of translational energy show that all types of energy (translational, rotational, and vibrational) affect the reactivity approximately equally for all three ions. Branching ratios have also been measured at 300 and 500 K in a SIFT for the N+ and N3+ reactions. An increase in the N2+ product at the expense of NO+ nondissociative charge transfer product occurs at 500 K with N+. The branching ratios for the reaction of N3+ with NO have also been measured in the SIFT, showing that only nondissociative charge transfer giving NO+ occurs up to 500 K. The current results are discussed in the context of the many previous studies of these ions in the literature.
Sublimation enthalpy of dye molecules measured using fluorescence
Authors: Stefanov André , Stibor Alexander , Dominguez-Clarimon Alex , Arndt Markus
Published: October 2004

We present an in-flight fluorescence detection scheme for molecular beams which is applied to determine the enthalpy of sublimation of dye molecules. We investigate tetraphenylporphyrin (TPP), porphine, and nile red, which are believed to be suitable candidates for molecular de Broglie wave interferometry [L. Hackermüller et al., Phys. Rev. Lett. 91, 090408, 2003]. The measured values are Hsub(TPP)=142±3 kJ/mol, Hsub(porphine)=87±3 kJ/mol, and Hsub(nile red)=66±2 kJ/mol. For TPP, sublimation enthalpies differ in the literature by more than a factor of 2. Our measurements confirm a value at the lower end of this scale. We discuss changes in the character of the molecular flow with the source temperature as a prime reason for discrepancies in the published data.
Raman spectra of ionic liquids: A simulation study of LaCl3 and its mixtures with alkali chlorides
Authors: Glover William J. , Madden Paul A.
Published: October 2004

Theoretical Raman spectra of the elpasolite-structured crystal Cs2NaLaCl6 and of molten mixtures of LaCl6 with NaCl and CsCl have been obtained from computer simulations in order to examine how the Raman spectra reflect the coordination structure around the La3+ ions. This system is a model for many other trivalent metal halides and for examining how the network structure of the pure melts is broken down by the addition of alkali halides with different structure-breaking powers. The results suggest a way of reconciling the conclusions of Raman studies about the structures of the melts with those of neutron and x-ray-diffraction studies, which have already been examined with the same simulation methods. The Raman spectra, both polarized and depolarized, are calculated from a model for the dependence of the polarizability of the system on the ionic coordinates which was inspired by electronic structure calculations of the polarizabilities of ions in a condensed phase environment. Some results on the lifetimes of the coordination complexes responsible for the appearance of the discrete Raman bands are discussed.
Semiquantal time-dependent Hartree approach to condensed phase chemical dynamics: Application to the system-bath model
Authors: Ando Koji
Published: October 2004

A semiquantal analysis of condensed phase chemical dynamics, outlined recently for a double-well linearly coupled to dissipative harmonic bath [K. Ando, Chem. Phys. Lett. 376, 532 (2003)], is formulated in detail to clarify its general features as well as the specifics of the linear and quadratic coupling cases. The theory may be called a “semiquantal time-dependent Hartree (SQTDH)” approach, as it assumes a factorized product of the squeezed coherent state wave packets for the variational subspace of the many-dimensional time-dependent wave function. Due to this assumption, it straightforwardly satisfies the canonicity condition introduced by Marumori et al. [Prog. Theor. Phys. 64, 1294 (1980)] and is described by a set of Hamilton equations of motion in an extended phase space that includes auxiliary coordinates representing the wave packet widths. The potential in the extended phase space provides a pictorial understanding of the quantum effects affected due to the bath coupling, e.g., suppression of the wave packet spreading in terms of the potential wall developing along the auxiliary coordinates. The idea is illustrated by prototypical models of quartic double-well and cubic metastable potentials linearly and quadratically coupled to the bath. Further applications and extensions, where the SQTDH method will offer a practical approach for introducing quantum effects into realistic molecular dynamics simulations, are also discussed.
Non-self-similar, linear dynamics during pinch-off of a hollow annular jet
Authors: Suryo Ronald , Doshi Pankaj , Basaran Osman A.
Published: October 2004

Based on an experimental and computational study of the breakup of a drop (jet) of small viscosity in an ambient fluid of large viscosity, Doshi et al. [Science 302, 1185 (2003)] have shown that the breakup of a drop (jet) of zero viscosity in a very viscous ambient fluid gives rise to an unexpected, nonuniversal form of singularity. Doshi et al. conjectured that the nonuniversal dynamics result from the fact that stresses exerted by the inner fluid are negligible. To verify this conjecture and overcome computational difficulties associated with simulating systems in which the disparity between the viscosities of the inner and the outer fluids is large, the breakup of an annular jet whose core is a gas of negligible viscosity is analyzed. Calculations show that as the jet’s minimum radius hmin→0, both core- and shell-side pressures remain bounded while surface tension pressure, which diverges as 1/hmin, is balanced by viscous normal stress exerted by the shell fluid. Simulations show that interfacial points move radially inward with the same velocity. Fourier decomposition of interface shapes confirms that the dynamics are linear. As hmin→0, the axial length scale remains finite, its value varying with imposed initial and boundary conditions. Thus, the breakup is not self-similar and the final breakup profile is nonuniversal.
Shear-induced phase separation in “nonentangled” oligomer mixture
Authors: Takenaka Mikihito , Miyazawa Masaaki , Nishitsuji Shotaro , Hashimoto Takeji
Published: October 2004

Shear-induced phase separation was found in “nonentangled” oligomer mixture. The sheared mixture in one phase becomes turbid and its scattering pattern exhibits so-called “butterfly pattern” which is commonly observed in shear-induced phase separation of semidilute polymer solutions. The origin of the shear-induced phase separation is found to be dynamical asymmetry due to the difference in the glass transition temperature.
The force generated by biological membranes on a polymer rod and its response: Statics and dynamics
Authors: Daniels D. R. , Turner M. S.
Published: October 2004

We propose a theory for the force exerted by a fluctuating membrane on a polymer rod tip. Using statistical mechanical methods, the expression for the generated force is written in terms of the distance of the rod tip from the membrane “frame.” We apply the theory in calculating the stall force and membrane displacement required to cease the growth of a growing fiber induced by membrane fluctuations, as well as the membrane force and membrane displacement required for rod/fiber buckling. We also consider the dynamics of a growing fiber tip under the influence of a fluctuation-induced membrane force. We discuss the importance of our results in various biological contexts. Finally, we present a method to simultaneously extract both the rigidity of the semiflexible rod and the force applied by, e.g., the membrane from the measurements of the bending fluctuations of the rod. Such a measurement of the force would give information about the thermodynamics of the rod polymerization that involves the usual Brownian ratchet mechanism.
Analysis of cooperativity and localization for atomic rearrangements
Authors: Trygubenko Semen A. , Wales David J.
Published: October 2004

We propose measures of localization and cooperativity for the analysis of atomic rearrangements. We show that for both clusters and bulk material cooperative rearrangements usually have significantly lower barriers than uncooperative ones, irrespective of the degree of localization. We also find that previous methods used to sample stationary points are biased towards rearrangements of particular types. Linear interpolation between local minima in double-ended transition state searches tends to produce cooperative rearrangements, while random perturbations of all the coordinates, as sometimes used in single-ended searches, have the opposite effect.
Van der Waals interactions in a dielectric with continuously varying dielectric function
Authors: Podgornik Rudi , Parsegian V. Adrian
Published: October 2004

We formulate and evaluate the van der Waals part of the free energy due to a dielectric profile that varies continuously throughout the space between two interacting bodies. Not considering the work needed to create the inhomogeneous dielectric profile, focusing only on that part of the free energy affected by the inhomogeneity, we compare the ensuing interaction free energy with that of the original Lifshitz formulation with its step function changes at material boundaries and uniform dielectric medium. Rather than the monotonically varying attraction between like bodies given by the original formulation, the inhomogeneous continuous dielectric function leads to attractions as well as repulsions. The Lifshitz result emerges naturally in the limit of separations much larger than the thickness of the interfaces.
Water-soluble silica-overcoated CdS:Mn/ZnS semiconductor quantum dots
Authors: Yang Heesun , Holloway Paul H. , Santra Swadeshmukul
Published: October 2004

Highly luminescent and photostable CdS:Mn/ZnS core/shell quantum dots are not water soluble because of their hydrophobicity. To create water-soluble quantum dots by an appropriate surface functionalization, CdS:Mn/ZnS quantum dots synthesized in a water-in-oil (W/O) microemulsion system (reverse micelles) were consecutively overcoated with a very thin silica layer (∼2.5 nm thick) within the same reverse micellar system. The water droplet serves as a nanosized reactor for the controlled hydrolysis and condensation of a silica precursor, tetraethyl orthosilicate (TEOS), using an ammonium hydroxide (NH4OH) catalyst. Structural characterizations with transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) indicate that the silica-quantum dot nanocomposites consist of a layered structure. Owing to the amorphous, porous nature of a silica layer, the optical and photophysical properties of silica-overcoated CdS:Mn/ZnS quantum dots are found to remain close to those of uncoated counterparts.
Applicability of continuum mechanics to pressure drop in small orifices
Authors: Kusmanto Febe , Jacobsen Elissa L. , Finlayson Bruce A.
Published: October 2004

Pressure drop in small orifices (8–109 μm) is examined by comparing the experimental data of Hasegawa, Suganuma, and Watanabe [Phys. Fluids 9, 1 (1997)] with theoretical and numerical solutions of the Navier–Stokes equations in order to test the claim by Hasegawa, Suganuma, and Watanabe that the data could not be explained by traditional continuum mechanics. The Reynolds number varies from zero (for the theoretical solution to Stokes flow) to 1000. The ratio of the orifice thickness to its diameter varies from 0.092 to 1.14. The primary increase in pressure drop is shown to be due to the effect of a finite thickness of the orifice, and this effect is predicted for Stokes flow by the theory of Dagan, Weinbaum, and Pfeffer [J. Fluid Mech. 115, 505 (1982)]. Numerical results presented here agree with Dagan, Weinbaum, and Pfeffer at Reynolds numbers below 10 and with the experimental data of Hasegawa, Suganuma, and Watanabe for low and intermediate Reynolds numbers. Most of the data can be predicted using traditional continuum mechanics.
Flow field properties local to near-wall shear layers in a low Reynolds number turbulent boundary layer
Authors: Klewicki J. C. , Hirschi C. R.
Published: October 2004

Combined hot-wire anemometry and flow visualizations are used to explore the properties of near-wall shear layers in a low Reynolds number turbulent boundary layer (Rθ=U∞θ/ν≅1200). The experiments employed two four-element probes positioned in the buffer layer. Data from these sensors were acquired synchronously with high speed, dual view, 35 mm movies of vaporized mineral oil fog illuminated via two orthogonal laser sheets. Near-wall shear layers were identified as satisfying the visual criterion of a narrow fissure of passive marker moving upward through the buffer layer in concert with a strong deceleration in the axial velocity trace. The present results reveal that the local flow fields satisfying these criteria regularly contain adjacent and spatially compact regions of opposing-sign spanwise vorticity ωz in the streamwise/wall-normal plane. A number of features were identified relative to whether ωz at the upper probe was positive or negative. In this regard, the configuration with positive ωz located above a region of negative ωz correlated with a more rapid wall-normal transport of the passive marker. Conditionally averaged measurements indicate that the flows local to near-wall shear layers have an attenuated opposing effect relative to the long time vωz contribution to the Reynolds stress gradient. Overall, these observations point to the change-of-scale mechanism rather than gradient transport in establishing the large Reynolds stress gradient in the buffer layer. Both spatial configurations of ωz were revealed to have association with an advective acceleration upstream of the detected shear layer. The scale of this accelerated region was larger for the condition of negative ωz located above a region of positive ωz. The detection of near-wall shear layers had a strong visual correlation with clusters of spanwise vortices, often occurring in counter-rotating pairs.
Molecular tagging velocimetry measurements of axial flow in a concentrated vortex core
Authors: Bohl Douglas G. , Koochesfahani Manoochehr M.
Published: October 2004

The characteristics of the axial flow within the core of a concentrated line vortex are investigated using molecular tagging velocimetry (MTV). A well-defined array of isolated vortices of alternating sign is generated in the wake of a NACA-0012 airfoil pitching sinusoidally at small amplitude and high reduced frequencies. The circulation and peak vorticity of the vortices are varied by the choice of oscillation frequency. Interaction of these two-dimensional vortices with the walls of the test section generates an axial flow within the vortex cores. The magnitude of the axial flow and its spatial/temporal characteristics are quantified using the MTV technique. Results show that the peak axial flow speeds can be very high, of the order maximum swirl speed of the vortices. The maximum axial speed ratio (maximum axial speed normalized by maximum swirl speed) is found to vary in the range 0.6–1.0 for the parameters investigated here. Initially, the axial flow is spatially confined in isolated structures corresponding to the core of vortices. As the vortex convects downstream, however, the spatial structure of axial flow changes from isolated regions to a continuous region for the highest reduced frequency investigated here. This change in structure is correlated with a significant decrease in the peak axial flow speed.
Tunable resonance hyper-Raman spectroscopy of second-order nonlinear optical chromophores
Authors: Shoute Lian C. T. , Blanchard-Desce Mireille , Kelley Anne Myers
Published: October 2004

Two-photon-resonant hyper-Raman spectra are reported for three “push–pull” conjugated organic chromophores bearing -NO2 acceptor groups, two dipolar and one octupolar. The excitation source is an unamplified picosecond mode-locked Ti:sapphire laser tunable from 720 to 950 nm. The linear resonance Raman spectra of the same molecules are measured using excitation from the laser second harmonic. Excitation on resonance with the lowest-lying band in the linear absorption spectrum yields nearly identical resonance Raman and resonance hyper-Raman spectra. However, excitation into a region that appears to contain more than one electronic transition gives rise to different intensity patterns in the linear and nonlinear spectra, indicating that different transitions contribute differently to the one-photon and two-photon oscillator strength. The promise of the hyper-Raman technique for examining electronic transitions that are both one- and two-photon allowed is discussed.
A bubble fission model for collapsing cavitation bubbles
Authors: Delale Can F. , Tunç Mutlu
Published: October 2004

A bubble fission model that takes into account energy dissipation during violent collapses of cavitation bubbles is introduced by assuming volume conservation and continuity of the gas pressure during instantaneous breakup, invoking either Rayleigh–Taylor instability or high speed microjet formation. In particular, a modified Rayleigh–Plesset equation is derived for the volumetric motion of the fission fragments in rebound. Results obtained under a pressure signal typical for cavitation bubbles confirm the scaling law of Brennen [C. E. Brennen, “Fission of collapsing cavitation bubbles,” J. Fluid Mech. 472, 153 (2002)] and the observations in experiments.
Ubiquitin-mediated fluorescence complementation reveals that Jun ubiquitinated by Itch/AIP4 is localized to lysosomes
Authors: Fang Deyu , Kerppola Tom K.
Published: October 2004

Ubiquitin family peptide modifications regulate the functions and stabilities of many proteins. We have developed an approach for the visualization of ubiquitinated proteins in living cells designated ubiquitin-mediated fluorescence complementation (UbFC). This approach is based on complementation among fragments of fluorescent proteins when they are brought together by the covalent conjugation of ubiquitin fused to one fragment to a substrate protein fused to a complementary fragment. The UbFC strategy enables simultaneous visualization of proteins modified by different ubiquitin family peptides and comparison of their effects on protein localization. Visualization of ubiquitinated Jun revealed that it was localized predominantly to cytoplasmic structures. In contrast, Jun conjugated to small ubiquitin-related modifier 1 (SUMO1) was localized to subnuclear foci. Comparison of the distribution of ubiquitinated Jun with markers for various cytoplasmic compartments revealed that ubiquitinated Jun was localized to lysosomal vesicles. Fractionation of cell lysates confirmed that the majority of ubiquitinated Jun partitioned to the cytoplasmic fraction, and density gradient centrifugation analysis demonstrated that it cosedimented with lysosomal β-hexosaminidase activity. Mutation of a recognition sequence for the E3 ligase Itch/AIP4 prevented Jun ubiquitination and stabilized it in cells. Inhibition of lysosomal protein degradation by bafilomycin or chloroquine stabilized Jun but had no effect on the stability of mutated Jun that was not ubiquitinated by Itch/AIP4. The visualization of ubiquitinated Jun in living cells has uncovered a lysosomal pathway for Jun degradation that involves ubiquitination by Itch/AIP4.
Multiple sequences in the C terminus of MaxiK channels are involved in expression, movement to the cell surface, and apical localization
Authors: Kwon Sang-Ho , Guggino William B.
Published: October 2004

Apical expression of the large-conductance, calcium- and voltage-activated potassium (MaxiK) channel in the cortical collecting duct is responsible for flow-stimulated potassium secretion. Here, we identify two cytoplasmic regions controlling apical expression of the MaxiK channel. Disruption of the proximal region results in the intracellular retention of the MaxiK channel without affecting channel assembly, thereby reducing surface expression. Coexpression of the WT channel with this mutant results in a reduction of WT MaxiK channel at the cell surface. Our data indicate that this proximal region is necessary for export of the MaxiK channel from the endoplasmic reticulum as a way to assess the final assembly of the channel. Deletion of a more distal region disrupts apical sorting, resulting in a nonpolarized distribution of the channel without impairing its surface delivery. In summary, we have found that sequences of amino acids in the C terminus of the MaxiK channel operate after the channel is assembled into a multimer and play a role in its expression, movement to the cell surface, and apical localization.
Requirement ofc-mybin T cell development and in mature T cell function
Authors: Lieu Yen K. , Kumar Atul , Pajerowski Anthony G. , Rogers Thomas J. , Reddy E. Premkumar
Published: October 2004

Previous reports have suggested that the protooncogenec-mybparticipates in T cell development in the thymus and mature T cell proliferation. We have generated two T cell-specificc-mybknockout mouse models, myb/LckCre and myb/CD4Cre. We have demonstrated thatc-mybis required for the development of thymocytes at the DN3 stage, for survival and proliferation of double-positive thymocytes, for differentiation of single-positive CD4 and CD8 T cells, and for the proliferative responses of mature T cells. In addition, our data show thatc-mybis directly involved in the formation of double-positive CD4+CD8+CD25+, CD4+CD25+, and CD8+CD25+ T cells, developmental processes that may imply a role forc-mybin autoimmune dysfunction.
Quantum speciation in
Aegilops
: Molecular cytogenetic evidence from rDNA cluster variability in natural populations
Authors: Raskina Olga , Belyayev Alexander , Nevo Eviatar
Published: October 2004

Data are presented on quantum speciation in the
Sitopsis
section of the genus
Aegilops
(
Poaceae
,
Monocotyledones
). Two small, peripheral, isolated, wild populations of annual cross-pollinated
Ae
.
speltoides
and annual self-pollinated
Ae
.
sharonensis
are located 30 m apart on different soil types. Despite the close proximity of the two species and their close relatedness, no mixed groups are known. Comparative molecular cytogenetic analysis based on the intrapopulation variability of rRNA-encoding DNA (rDNA) chromosomal patterns of individual
Ae
.
speltoides
geno-types revealed an ongoing dynamic process of permanent chromosomal rearrangements. Chromosomal mutations can arise
de novo
and can be eliminated. Analysis of the progeny of the investigated genotypes testifies that inheritance of
de novo
rDNA sites happens frequently. Heterologous recombination and/or transposable elements-mediated rDNA transfer seem to be the mechanisms for observed chromosomal repatterning. Consequently, several modified genomic forms, intermediate between
Ae
.
speltoides
and
Ae
.
sharonensis
, permanently arise in the studied wild population of
Ae
.
speltoides
, which make it possible to recognize
Ae
.
sharonensis
as a derivative species of
Ae
.
speltoides
, as well as to propose rapidness and canalization of quantum speciation in
Sitopsis
species.
Do Economic Reforms Accelerate Urban Growth? The Case of China
Authors: Anderson Gordon , Ge Ying
Published: October 2004

This paper examines the determinants of city growth in China. Evidence is provided that economic reforms played an important role in accelerating urban growth. The relative magnitude of the state sector has a negative impact on city growth and the city's openness to foreign direct investment has a positive impact on city growth. The results also lend support to the impact of other factors on urban growth, such as geography, industrial structure and human capital accumulation.
Value of subtraction in fat‐saturated three‐dimensional contrast‐enhanced magnetic resonance angiography of the hemodialysis fistula
Authors: Takahashi N. , Sato M. , Niitsu M. , Saida Y.
Published: October 2004

Purpose: To evaluate image subtraction in a three‐dimensional contrast‐enhanced magnetic resonance angiography (3D CE‐MRA) using fat suppression for the hemodialysis fistula.

Material and Methods: Fifteen patients suffering from hemodialysis fistula dysfunction were imaged with 3D CE‐MRA using fat suppression and digital subtraction angiography (DSA). Non‐subtracted and subtracted MRA images using maximum intensity projection (MIP) were constructed and the validity of the MRA interpretations of the degree of vascular stenoses was evaluated using DSA as the standard of reference. Image quality was assessed using qualitative analysis (vessel contrast) and quantitative analysis (contrast‐to‐noise ratio (CNR) of the vessel versus the background).

Results: In the vessels with stenosis of 50% or greater, the sensitivity and specificity of the non‐subtracted MRA were 89.5% and 81.8%, respectively, and of the subtracted MRA 89.5% and 86.4%, respectively. There was no significant difference in the detectability of stenoses between either MRA. The vessel contrast of the anterior interosseous artery and the CNR of the anterior interosseous artery versus the background on the subtracted MRA were significantly superior to those on the non‐subtracted MRA. With regard to the radial artery and cephalic vein, there was no significant difference in the vessel contrast and CNR between either MRA.

Conclusion: Both subtracted and non‐subtracted MRA techniques are useful in detecting hemodialysis fistula dysfunction.
Spontaneous involution of a non‐optic astrocytoma in neurofibromatosis type I: serial magnetic resonance imaging evaluation
Authors: Cakirer S. , Karaarslan E.
Published: October 2004

A patient with neurofibromatosis type I (NF1) was followed‐up with serial magnetic resonance imaging (MRI) studies over a period of 6 years. A contrast‐enhancing lesion of the internal capsule, histologically proven to be pilocytic astrocytoma through stereotactic brain biopsy with mass effect and associated edema, was detected to reveal spontaneous involution on follow‐up MRI studies. Although spontaneous regression of gliomas of the optic pathway‐hypothalamus in patients with NF1 is relatively common in the literature, spontaneous involution of non‐optic (i.e. areas other than optic pathways and hypothalamus) gliomas is rarely reported. Conservative management with follow‐up MRI studies should be considered for non‐optic glial tumors and tumor‐like masses in patients with NF1, and surgical treatment should not be considered unless the lesions exhibit a rapid or unrelenting growth on serial MRI studies or produce significant clinical deterioration.
Persistent primitive trigeminal artery associated with aneurysm: report of two cases and review of the literature
Authors: Li M. H. , Li W. B. , Pan Y. P. , Fang C. , Wang W.
Published: October 2004

We present two cases of persistent primitive trigeminal artery (PPTA) associated with a giant aneurysm originating at the opening of the PPTA on the internal carotid artery (ICA). In one case, opening of the PPTA occurred 4 months after balloon occlusion of the ICA, when a giant aneurysm located at the cavernous segment of the ICA was being treated. The PPTA was occluded successfully using a Guglielmi detachable coil (GDC). A vertebral artery approach was taken. This is the first report of the opening of a PPTA associated with contrast filling of the aneurysm after balloon occlusion of the parent artery. The possibility of contrast filling of the aneurysm via potential PPTA should therefore be considered in the event of an ICA aneurysm with parent artery occlusion.
Repeatability of sonographic measurements in clubfeet
Authors: Aurell Y. , Adlercreutz C. , Andriesse H. , Jonsson K.
Published: October 2004

Purpose: To assess the intra‐ and interobserver agreement of ultrasound assessment of clubfoot patho‐anatomy in early childhood.

Material and Methods: Seventeen clubfeet in 12 children were sequentially scanned by 2 examiners and repeat assessments were carried out independently. Three well‐defined imaging planes were chosen to evaluate navicular displacement: the medial malleolus‐navicular (MM‐N) distance, soft tissue thickness, talar deformity and the calcaneo‐cuboid (C‐C) distance. Intra‐ and interobserver agreement was analysed using Cohen's kappa for the discrete variables and by Bland‐Altman's graphic technique for measurements.

Results: Kappa values for intra‐observer agreement were 0.82 for navicular displacement, 0.93 for “talar head pointing laterally”, and 0.70 for medial deviation of the talar neck. The corresponding interobserver kappa values were 0.70, 0.68, and 0.36. The mean difference between the two observers for the MM‐N distance was 0.42±3.0 mm and for the soft tissue thickness 0.35±2.0 mm; the C‐C distance showed a mean interobserver distance of 0.0±2.8 mm.

Conclusion: The imaging planes used to study the talo‐navicular and calcaneo‐cuboid relationships are reproducible and relatively easy to learn. Intra‐ and interobserver assessments were acceptable for MM‐N distance, soft tissue thickness, navicular displacement and “talar head pointing laterally”, but questionable for the C‐C distance and medial deviation of the talar neck.
Usefulness of diffusion tensor imaging of white matter in alzheimer disease and vascular dementia
Authors: Sugihara S. , Kinoshita T. , Matsusue E. , Fujii S. , Ogawa T.
Published: October 2004

Purpose: To evaluate the usefulness of diffusion tensor imaging in detecting the water diffusivity caused by neuropathological change in Alzheimer disease and vascular dementia.

Material and Methods: Twenty patients with Alzheimer disease, 20 with vascular dementia, and 10 control subjects were examined. Diffusion tensor imaging applied diffusion gradient encoding in six non‐collinear directions. Fractional anisotropy values were compared in the genu and splenium of the corpus callosum, and anterior and posterior white matter among the three groups.

Results: In the patients with Alzheimer disease, fractional anisotropy values of the posterior white matter were significantly lower than those of controls. In patients with vascular dementia, fractional anisotropy values of the anterior white matter tended to be lower than those of the posterior white matter ( P=0.07).

Conclusion: Diffusion tensor imaging reflects the neuropathological changes in the white matter, and may be useful in the diagnosis of Alzheimer disease and vascular dementia.
XBP1
Authors: Sriburi Rungtawan , Jackowski Suzanne , Mori Kazutoshi , Brewer Joseph W.
Published: October 2004

When the protein folding capacity of the endoplasmic reticulum (ER) is challenged, the unfolded protein response (UPR) maintains ER homeostasis by regulating protein synthesis and enhancing expression of resident ER proteins that facilitate protein maturation and degradation. Here, we report that enforced expression of XBP1(S), the active form of the XBP1 transcription factor generated by UPR-mediated splicing of XBP1 mRNA, is sufficient to induce synthesis of phosphatidylcholine, the primary phospholipid of the ER membrane. Cells overexpressing XBP1(S) exhibit elevated levels of membrane phospholipids, increased surface area and volume of rough ER, and enhanced activity of the cytidine diphosphocholine pathway of phosphatidylcholine biosynthesis. These data suggest that XBP1(S) links the mammalian UPR to phospholipid biosynthesis and ER biogenesis.
BagBoosting for tumor classification with gene expression data
Authors: Dettling Marcel
Published: October 2004

Motivation: Microarray experiments are expected to contribute significantly to the progress in cancer treatment by enabling a precise and early diagnosis. They create a need for class prediction tools, which can deal with a large number of highly correlated input variables, perform feature selection and provide class probability estimates that serve as a quantification of the predictive uncertainty. A very promising solution is to combine the two ensemble schemes bagging and boosting to a novel algorithm called BagBoosting.

Results: When bagging is used as a module in boosting, the resulting classifier consistently improves the predictive performance and the probability estimates of both bagging and boosting on real and simulated gene expression data. This quasi-guaranteed improvement can be obtained by simply making a bigger computing effort. The advantageous predictive potential is also confirmed by comparing BagBoosting to several established class prediction tools for microarray data.

Availability: Software for the modified boosting algorithms, for benchmark studies and for the simulation of microarray data are available as an R package under GNU public license at http://stat.ethz.ch/~dettling/bagboost.html
TFExplorer: integrated analysis database for predicted transcription regulatory elements
Authors: Kim Jinsoo , Seo Jungmin , Lee Young Seek , Kim Sangsoo
Published: October 2004

Summary: TFExplorer is a web-based integrated database for predicted regulatory elements in human, mouse and rat. It shows predicted binding sites of transcription factors in the promoter regions, along with their phylogenetic footprinting information. In addition, TFExplorer can search for genes that have a given sequence pattern in their promoter regions using the motif-searching method.

Availability: TFExplorer is freely available at http://mars.kribb.re.kr:8080/tfExplorer/

Contact:  sskimb@kribb.re.kr
CANADIAN REFLECTIONS ON THE TOBACCO WARS: SOME UNINTENDED CONSEQUE5NCES OF MASS TORT LITIGATION
Authors: Berryman Jeff
Published: October 2004

During the 1990s many Commonwealth legislatures enacted ‘class action’ or ‘representative proceedings’ legislation.1The main justification for these initiatives was to increase access to justice for claimants particularly where the injury was widespread but the harm suffered by any particular individual was small. Much of this legislation built on developments in the United States, which had developed a sizable jurisprudence in the area. ‘Mass torts’, those defined as having a large impact engaging multiple claimants, have often formed the cause of action in US class actions. A review of the website ‘Big Class Actions‘,2which lists over one hundred current suits in the United States, is instructive on how the class action industry has grown in that country.
THE MOX PLANT LITIGATION: THE FIRST HALF-LIFE
Authors: Churchill Robin , Scott Joanne
Published: October 2004

In 2001 Ireland commenced litigation against the United Kingdom (UK) over the construction and operation of a plant to produce mixed oxide fuels at the Sellafield nuclear complex in north-west England. This litigation, which had been only partially concluded at the time of writing, raises a series of fascinating and often complex issues of both international and EU law. These include the potential for overlapping jurisdiction between different international tribunals; the division of competence between the EC and its Member States in relation to participation in treaties; and the use of litigation as a strategy for settling inter-State disputes. The aim of this article, apart from giving a snapshot of the position that the increasingly tortuous course of this litigation had reached by January 2004, is to explore these issues. The article begins by setting out the background to the litigation and giving a quick overview of its course so far. It then explores in more detail the questions of overlapping jurisdiction of international tribunals and of EC law raised by the litigation, before concluding with a few, rather speculative, thoughts about Ireland's choice of litigation as a strategy.
DECISIONS OF INTERNATIONAL TRIBUNALS: INTERNATIONAL COURT OF JUSTICE: I. APPLICATION FOR REVISION OF THE JUDGMENT OF 11 JULY 1996 IN THE CASE CONCERNING APPLICATION OF THE CONVENTION ON THE PREVENTION AND PUNISHMENT OF THE CRIME OF GENOCIDE (BOSNIA AND HERZEGOVINA v YUGOSLAVIA), PRELIMINARY OBJECTIONS (YUGOSLAVIA v BOSNIA AND HERZEGOVINA), JUDGMENT OF 3 FEBRUARY 2003
Authors: Tsagourias Nicholas
Published: October 2004

In its judgment of 3 February 2003, the International Court of Justice (ICJ) declared the application submitted by the Federal Republic of Yugoslavia (FRY) for revision of its 1996 judgment concerning the Application of the Convention on the Prevention and Punishment of the Crime of Genocide, inadmissible.1The Court found that the request for revision was not based on the ‘discovery’ of a ‘fact’ and, therefore, one of the conditions of Article 61 of the Statute of the Court was not satisfied. This commentary will appraise the decision by examining the formal and substantive criteria for revision, a rather neglected and underused process.2
II. AVENA AND OTHER MEXICAN NATIONALS {MEXICO v UNITED STATES OF AMERICA), PROVISIONAL MEASURES, ORDER OF 5 FEBRUARY 2003
Authors: Ghandhi Sandy
Published: October 2004

The International Court of Justice is not a human rights court but it does hear human rights cases.1This is hardly remarkable. As Professor Ian Brownlie has pointed out ‘[h]uman rights problems occur in specific legal contexts. The issues may arise… within the framework of a standard-setting convention, or within general international law.’2Because human rights treaties normally have their own dispute settlement procedure, the situations in which the International Court of Justice is more likely to have to grapple with human rights issues lie within the realms of general international law or in non-human rights specific treaty provisions, which may, nevertheless, raise such issues. In addition, some human rights treaties, such as the Convention on the Prevention and Punishment of the Crime of Genocide 1948, contain provisions specifically referring disputes to the International Court of Justice.3Thus, it should come as no surprise that the Court has been involved in a number of cases involving human rights questions.