bluuebunny/crossref_metadata_2025 huggingface dataset:
Transport, magnetic, specific heat, internal friction, and shear modulus in the charge ordered La0.25Ca0.75MnO3 manganite
Authors: Zheng R. K. , Tang A. N. , Yang Y. , Wang W. , Li G. , Li X. G. , Ku H. C.
Published: June 2003

The resistivity, magnetization, specific heat, shear modulus, and internal friction in the charge-ordered (CO) La0.25Ca0.75MnO3 were studied. The electronic conduction in the CO state was found to obey Mott's variable-range hopping model with a change in the localization length ξ near TN. A large decrease of the magnetization was observed between the Néer temperature TN and the charge ordering transition temperature TCO, which was attributed to the consequence of the orbital ordering. Drastic stiffening in shear modulus and an internal friction peak appeared just below TCO, and were explained as due to the coupling between the lattice strain and the orbital degree of freedom. A small upturn of the magnetization and a small softening of the ultrasound near TCA≈42 K suggest the evolution of spin canting from the matrix of long-range antiferromagnetic state.
Passive vibration isolation using a Roberts linkage
Authors: Garoi F. , Winterflood J. , Ju L. , Jacob J. , Blair D. G.
Published: June 2003

The article present an ultralow frequency passive vibration isolation device as part of the preisolation stage for the Australian International Gravitational Observatory (AIGO). This isolator is based on the Roberts linkage and simulates a very long radius conical pendulum to provide two-dimensional isolation. It is designed as the second horizontal isolation component of the preisolator and it will support the remaining four isolation stages of the AIGO vibration isolator chain. A description of the device together with a theoretical model and its measured isolation performance are presented. With the current setup, we obtained 32 dB of isolation at 1 Hz.
Free-electron-laser-based biophysical and biomedical instrumentation
Authors: Edwards G. S. , Austin R. H. , Carroll F. E. , Copeland M. L. , Couprie M. E. , Gabella W. E. , Haglund R. F. , Hooper B. A. , Hutson M. S. , Jansen E. D. , Joos K. M. , Kiehart D. P. , Lindau I. , Miao J. , Pratisto H. S. , Shen J. H. , Tokutake Y. , van der Meer A. F. G. , Xie A.
Published: June 2003

A survey of biophysical and biomedical applications of free-electron lasers (FELs) is presented. FELs are pulsed light sources, collectively operating from the microwave through the x-ray range. This accelerator-based technology spans gaps in wavelength, pulse structure, and optical power left by conventional sources. FELs are continuously tunable and can produce high-average and high-peak power. Collectively, FEL pulses range from quasicontinuous to subpicosecond, in some cases with complex superpulse structures. Any given FEL, however, has a more restricted set of operational parameters. FELs with high-peak and high-average power are enabling biophysical and biomedical investigations of infrared tissue ablation. A midinfrared FEL has been upgraded to meet the standards of a medical laser and is serving as a surgical tool in ophthalmology and human neurosurgery. The ultrashort pulses produced by infrared or ultraviolet FELs are useful for biophysical investigations, both one-color time-resolved spectroscopy and when coupled with other light sources, for two-color time-resolved spectroscopy. FELs are being used to drive soft ionization processes in mass spectrometry. Certain FELs have high repetition rates that are beneficial for some biophysical and biomedical applications, but confound research for other applications. Infrared FELs have been used as sources for inverse Compton scattering to produce a pulsed, tunable, monochromatic x-ray source for medical imaging and structural biology. FEL research and FEL applications research have allowed the specification of spin-off technologies. On the horizon is the next generation of FELs, which is aimed at producing ultrashort, tunable x rays by self-amplified spontaneous emission with potential applications in biology.
Vacuum level alignment of pentacene on LiF/Au
Authors: Watkins N. J. , Gao Y.
Published: June 2003

We examined the interfaces of pentacene on LiF/Au substrates as a function of LiF thickness. We found that, regardless of the thickness of LiF, upon pentacene deposition onto LiF, the pentacene vacuum level aligns with that of LiF. We also show that LiF exhibits an interface dipole when deposited onto Au and that the magnitude of the interface dipole increases as the LiF thickness increases. The change in vacuum level as a function of LiF thickness allows the Fermi level position within the band gap of pentacene to be moved from 0.5 eV above the highest occupied molecular orbital to 2.1 eV above the highest occupied molecular orbital. This produces a hole injection barrier of 0.5 eV at the pentacene/Au interface and an electron injection barrier of 0.1 eV at the pentacene/40-Å-LiF/Au interface.
Enhanced ionization in the cylindrical Hall thruster
Authors: Smirnov A. , Raitses Y. , Fisch N. J.
Published: June 2003

Conventional annular Hall thrusters do not scale efficiently to low power. An alternative approach, a cylindrical Hall thruster with a cusp-type magnetic field distribution, has been investigated. A relatively large 9-cm-diam version of a cylindrical thruster, operated in 300–1000 W power range, and the 2.6 cm miniaturized cylindrical Hall thruster, operated in the power range 50–300 W, exhibited performance comparable with conventional annular Hall thrusters of the similar size. The cylindrical thrusters have unusually high propellant utilization, compared to conventional Hall thrusters. Numerical simulations, performed within the framework of a quasi-one-dimensional stationary thruster model, show that the increase in the propellant utilization does not appear to be quantitatively explained by a reduction of plasma wall losses. A more complete theoretical model, likely including kinetic effects, will be necessary to explain the observed propellant utilization effect.
Experimental characterization and modeling of the reliability of three-terminal dual-damascene Cu interconnect trees
Authors: Gan C. L. , Thompson C. V. , Pey K. L. , Choi W. K.
Published: June 2003

Electromigration tests on Cu dual-damascene interconnect tree structures consisting of straight via-to-via (or contact-to-contact) lines with an extra via in the middle of the line have been carried out. Like Al-based interconnects, the reliability of a segment in a Cu-based interconnect tree strongly depends on the stress conditions of connected segments. The analytic model based on a nodal analysis developed for Al trees gives a conservative estimate of the lifetime of Cu-based interconnect trees. However, there are important differences in the results obtained under similar test conditions for Al-based and Cu-based interconnect trees. These differences are thought to be associated with variations in the architectural schemes of the two metallization systems. The absence of a conducting electromigration-resistant overlayer in Cu technology and the low critical stress for void nucleation at the Cu/interlevel diffusion barrier interface (e.g., the Cu/Si3N4 interface) leads to different failure modes between Cu and Al interconnects. As a result, the most highly stressed segment in a Cu-based interconnect tree is not always the least reliable. Moreover, the possibility of liner rupture at stressed dual-damascene vias lead to significant differences in tree reliabilities in Cu compared to Al. While an interconnect tree can be treated as a fundamental unit whose reliability is independent of that of other units in Al-based interconnect architectures, interconnect trees cannot be treated as fundamental units for circuit-level reliability analyses for Cu-based interconnects.
Six-band k⋅p calculation of the hole mobility in silicon inversion layers: Dependence on surface orientation, strain, and silicon thickness
Authors: Fischetti M. V. , Ren Z. , Solomon P. M. , Yang M. , Rim K.
Published: June 2003

A six-band k⋅p model has been used to study the mobility of holes in Si inversion layers for different crystal orientations, for both compressive or tensile strain applied to the channel, and for a varying thickness of the Si layer. Scattering assisted by phonons and surface roughness has been accounted for, also comparing a full anisotropic model to an approximated isotropic treatment of the matrix elements. Satisfactory qualitative (and in several cases also quantitative) agreement is found between experimental data and theoretical results for the density and temperature dependence of the mobility for (001) surfaces, as well as for the dependence of the mobility on surface orientation [for the (011) and (111) surfaces]. Both compressive and tensile strain are found to enhance the mobility, while confinement effects result in a reduced hole mobility for a Si thickness ranging from 30 to 3 nm.
Nucleation and interface formation mechanisms in atomic layer deposition of gate oxides
Authors: Frank Martin M. , Chabal Yves J. , Wilk Glen D.
Published: June 2003

We present an in situ infrared spectroscopic study of the interface formation during atomic layer deposition of alternative high-permittivity (high-κ) gate dielectrics. Layer-by-layer oxide growth may be achieved by alternating pulses of a molecular metal precursor (e.g., trimethylaluminum for aluminum oxide growth) and water vapor. Contrary to common belief, we find that the metal precursor, not the oxidizing agent, is the key factor to control Al2O3 nucleation on hydrogen-terminated silicon. Metal surface species catalyze subsurface Si oxidation. These findings have direct implications on growth conditions to optimize semiconductor-dielectric interfaces.
Cubic GaN formation in Mn/GaN multilayer films grown on 6H-SiC(0001)
Authors: Cui Y. , Lazorov V. K. , Goetz M. M. , Liu H. , Robertson D. P. , Gajdardziska-Josifovska M. , Li L.
Published: June 2003

Cubic GaN was grown on 6H-SiC(0001) by electron-cyclotron resonance plasma-assisted molecular-beam epitaxy. The growth process consisted of first depositing a 20-nm GaN buffer, followed by ten periods of alternating layers of 1 monolayer (ML) Mn and 10 ML GaN, and finally capped with 30 nm GaN. High-resolution transmission electron micrographs of film cross sections were recorded and digital diffractograms were calculated to determine the lattice structures of the different film layers. It was found that the crystal structure in the GaN buffer and capping layer matches the 2H-wurtzite GaN. However, uniform cubic zinc-blende GaN phase was observed in place of the nominal multilayer Mn/GaN region. The density of defects typically observed in GaN films is drastically reduced within the cubic and capping layer, indicating improved film quality possibly due to the surfactant effect of Mn. Based on the one-dimensional Ising model of polytype formation, a mechanism is proposed to explain the growth of cubic GaN in the Mn/GaN region.
Light amplification in semiconductor nanocrystals: Quantum rods versus quantum dots
Authors: Htoon H. , Hollingworth J. A. , Malko A. V. , Dickerson R. , Klimov V. I.
Published: June 2003

We perform side-by-side comparison of optical gain properties of spherical and elongated nanocrystals (quantum dots and quantum rods, respectively). This comparison indicates that elongated nanoparticles provide several features beneficial for lasing applications, such as enhanced absorption cross sections (and hence reduced lasing threshold and improved photostability), increased optical gain lifetime, and extended optical gain spectral range through the use of transitions that involve both ground and excited electronic states.
Enhanced carrier-mediated ferromagnetism in GaMnN by codoping of Mg
Authors: Kim K. H. , Lee K. J. , Kim D. J. , Kim H. J. , Ihm Y. E. , Kim C. G. , Yoo S. H. , Kim C. S.
Published: June 2003

The effects of Mg codoping on the structural, electronic transport, and magnetic properties of GaMnN films are investigated. Mg was shown to compete with Mn for incorporation into the growing films at impingement, and to replace Mn. The partial replacement of Mn by Mg in GaMnN has resulted in an increase of conductivity of the region. The enhanced transport property due to the highly efficient dopant Mg resulted in a remarkable increase of the saturation magnetization, indicating an interaction between Mn and Mg for the carrier-mediated ferromagnetism. The increased carrier population by Mg codoping enabled a full mediation among the Mn atoms, and consequently, suppressed the paramagnetic rise in the temperature-dependent magnetization measurement.
Analysis of light propagation in index-tunable photonic crystals
Authors: Xiong Sibei , Fukshima Hiroshi
Published: June 2003

Propagation behaviors of light in index-tunable photonic crystals were analyzed by calculating the directions of the group velocity of light in the photonic crystals. Simulation results reveal that the band structures of tunable photonic crystals are highly anisotropic and the equifrequency surface curves in the wave-vector space of photonic crystals can show acute variation corresponding to an index change when operation frequency and incident angle are carefully selected. In the case of a triangular system composed of ferroelectric background and circular airholes, “on/off” switching can be operated when operation frequency a/λ is 0.4205 and the incident angle falls into a window of 32°–49°. Light can deflect 40° when the operation frequency a/λ and incident angle are 0.5372 and 23°, respectively. Two types of optical switches based on the anisotropic characteristics of index-tunable photonic crystals are proposed, which will find great potential applications in optical communications.
Temperature dependence of the energy gap and free carrier absorption in bulk InAs0.05Sb0.95 single crystals
Authors: Bansal Bhavtosh , Dixit V. K. , Venkataraman V. , Bhat H. L.
Published: June 2003

Temperature dependence of the energy gap and free carrier absorption in a high-quality InAs0.05Sb0.95 single crystal was studied between 90 K and 430 K through the absorption spectra. At this alloy concentration, the room-temperature energy gap was measured to be 0.15 eV. Varshni- and the Bose–Einstein-type fit parameters were obtained from the measured temperature dependence of the energy gap, and the latter gave the zero-temperature gap to be 0.214 eV. It was found that although Weider’s empirical formula for the dependence of the energy gap on temperature and the alloy concentration agrees with the value of the gap at room temperature, it is inaccurate in describing its temperature dependence. From the free carrier absorption measurements, the phonon limited cross section of 7.35×10−16 cm2 at 15 μm was deduced at room temperature.
Paramagnetic to antiferromagnetic phase transformation in sputter deposited Pt–Mn thin films
Authors: Ladwig Peter F. , Chang Y. Austin , Linville Eric S. , Morrone Augusto , Gao Jenny , Pant Bharat B. , Schlutz Alan E. , Mao Sining
Published: June 2003

Sputter deposited, equiatomic Pt–Mn thin films used in giant magnetoresistive spin valves are found not to exist in the antiferromagnetic state required for device operation. Therefore, an annealing step is needed to induce a phase transformation from the as-deposited, paramagnetic A1 (fcc) phase to the antiferromagnetic L10 phase. The L10 phase is the thermodynamically stable configuration, but favorable kinetics for the transformation were only found above 260 °C. The A1 to L10 phase transformation was studied by x-ray diffraction, transmission electron microscopy and differential scanning calorimetry (DSC). The nucleation and growth conditions were evaluated and an exothermic transformation enthalpy of −12.1 kJ/mol of atoms was determined. The kinetics of the reaction were simulated using the Johnson–Mehl–Avrami analysis, where the necessary parameters were determined by the Kissinger and Ozawa methods from constant scanning rate DSC experiments [H. Yinnon and D. R. Uhlmann, J. Non-Cryst. Solids 54, 253 (1983)]. The resulting simulations were compared to DSC data as well as isothermal x-ray peak shift data and a reasonable agreement was obtained.
Electron transport properties in magnetic tunnel junctions with epitaxial NiFe (111) ferromagnetic bottom electrodes
Authors: Yu Ji Hyung , Lee Hyuck Mo , Ando Yasuo , Miyazaki Terunobu
Published: June 2003

By employing epitaxial NiFe (111) films as ferromagnetic bottom electrodes, magnetic tunnel junctions with layer sequence of Si (111)/epitaxial Ag/epitaxial Cu/epitaxial NiFe/Al-oxide/CoFe/IrMn/NiFe/Ta were prepared. High tunneling magnetoresistance (TMR) ratios were obtained and the bias dependence of TMR was remarkably reduced. The reason for the small bias dependence of TMR was explained by inelastic electron tunneling spectroscopy. It was clearly elucidated that a well-defined sharp interface formed between the tunnel barrier and the ferromagnetic electrode that is nearly free of crystalline defects. This magnetic tunnel junction has a large capability in engineering aspects if we can reduce the barrier thickness further by decreasing the interface roughness.
Getting ahead of IVR: A demonstration of mid-infrared induced molecular dissociation on a sub-statistical time scale
Authors: Windhorn Lars , Yeston Jake S. , Witte Thomas , Fuß Werner , Motzkus Marcus , Proch Detlev , Kompa Karl-Ludwig , Moore C. Bradley
Published: June 2003

Gaseous diazomethane (CH2N2) has been irradiated with femtosecond laser pulses tuned to the CNN asymmetric stretch at 2100 cm−1 in the mid-infrared. Laser-induced fluorescence detection of CH21 [537 nm, b̃1B1(0 16 0)←ã1A1(0 0 0)] confirms infrared (IR) multiphoton-induced scission of the C–N bond on two distinct time scales, 480±70 fs and 36±8 ps. The longer time scale is consistent with a statistical dissociation process; the shorter one is indicative of directed dissociation, which occurs more rapidly than statistical intramolecular vibrational energy redistribution because of direct coupling of the vibrational energy from the IR-excitation mode into the reaction coordinate. Anisotropy measurements demonstrate that the CH2 group bends significantly out of the molecular plane prior to the dissociation.
Toxicology analysis by means of the JSM-method
Authors: Blinova V. G. , Dobrynin D. A. , Finn V. K. , Kuznetsov S. O. , Pankratova E. S.
Published: June 2003

Motivation: A model for learning potential causes of toxicity from positive and negative examples and predicting toxicity for the dataset used in the Predictive Toxicology Challenge (PTC) is presented. The learning model assumes that the causes of toxicity can be given as substructures common to positive examples that are not substructures of negative examples. This assumption results in the choice of a learning model, called the JSM-method, and a language for representing chemical compounds, called the Fragmentary Code of Substructure Superposition (FCSS). By means of the latter, chemical compounds are represented as sets of substructures which are ‘biologically meaningful’ from the expert point of view.

Results: The chosen learning model and representation language show comparatively good performance for the PTC dataset: for three sex/species groups the predictions were ROC optimal, for one group the prediction was nearly optimal. The predictions tend to be conservative (few predictions and almost no errors), which can be explained by the specific features of the learning model.

Availability: by request to finn@viniti.ru; serge@viniti.ru, http://ki-www2.intellektik.informatik.tu-darmstadt.de/~jsm/QDA

Contact: serge@viniti.ru

* To whom correspondence should be addressed.
Putting the Predictive Toxicology Challenge
into perspective: reflections on the results
Authors: Benigni Romualdo , Giuliani Alessandro
Published: June 2003

Motivation: Chemical carcinogenicity is of primary interest, because it drives much of the current regulatory actions regarding new and existing chemicals, and its experimental determination involves time-consuming and expensive animal testing. Both academia and private companies are actively trying to develop SAR and QSAR models. This paper reviews the new Predictive Toxicology Challenge (PTC) results, by putting them into the context of previous attempts.

Results: A marked dependency of the prediction ability of the different algorithms on the training sets was observed, pointing to a still insufficient coverage of the chemical carcinogens ‘universe’. A theoretical treatment of the possible developments of the Artificial Intelligence approaches is sketched.

Contact: rbenigni@iss.it

* To whom correspondence should be addressed.
Fast sequence clustering using a suffix array algorithm
Authors: Malde Ketil , Coward Eivind , Jonassen Inge
Published: June 2003

Motivation: Efficient clustering is important for handling the large amount of available EST sequences. Most contemporary methods are based on some kind of all-against-all comparison, resulting in a quadratic time complexity. A different approach is needed to keep up with the rapid growth of EST data.

Results: A new, fast EST clustering algorithm is presented. Sub-quadratic time complexity is achieved by using an algorithm based on suffix arrays. A prototype implementation has been developed and run on a benchmark data set. The produced clusterings are validated by comparing them to clusterings produced by other methods, and the results are quite promising.

Availability: The source code for the prototype implementation is available under a GPL license from http://www.ii.uib.no/~ketil/bio/

Contact: ketil@ii.uib.no

* To whom correspondence should be addressed.
Pyranose oxidase identified as a member of the GMC
oxidoreductase family
Authors: Albrecht Mario , Lengauer Thomas
Published: June 2003

Fungal pyranose oxidase is a flavoenzyme whose preferred substrate among several monosaccharides is d-glucose. After a comprehensive analysis of conserved features in a structure-based multiple sequence alignment of homologous proteins, we could classify this enzyme into the GMC oxidoreductase family. The identified homology also suggests a three-dimensional protein structure similar to the functionally related glucose oxidase.

Contact: mario.albrecht@mpi-sb.mpg.de

* To whom correspondence should be addressed.
A comparison of parametric versus permutation
methods with applications to general and temporal
microarray gene expression data
Authors: Xu Ronghui , Li Xiaochun
Published: June 2003

Motivation: In analyses of microarray data with a design of different biological conditions, ranking genes by their differential‘ importance’ is often desired so that biologists can focus research on a small subset of genes that are most likely related to the experiment conditions. Permutation methods are often recommended and used, in place of their parametric counterparts, due to the small sample sizes of microarray experiments and possible non-normality of the data. The recommendations, however, are based on classical knowledge in the hypothesis test setting.

Results: We explore the relationship between hypothesis testing and gene ranking. We indicate that the permutation method does not provide a metric for the distance between two underlying distributions. In our simulation studies permutation methods tend to be equally or less accurate than parametric methods in ranking genes. This is partially due to the discreteness of the permutation distributions, as well as the non-metric property. In data analysis the variability in ranking genes can be assessed by bootstrap. It turns out that the variability is much lower for permutation than parametric methods, which agrees with the known robustness of permutation methods to individual outliers in the data.

Contact: rxu@jimmy.harvard.edu

* To whom correspondence should be addressed.
University libraries in Iran: a study based on published sources
Authors: Reza Davarpanah Mohammed
Published: June 2003

This paper examines the contemporary university library system in Iran. The eight key factors studied are: library systems, resources and collection building, technical processing, services, information technology applications, co‐operation and exchange of information resources, administration and staffing, and financial administration. While examining these variables, the problems being faced by university libraries are also discussed and suggestions for dealing with them are offered.
Human resource management issues in audit firms: a research agenda
Authors: Brierley John A. , Gwilliam David R.
Published: June 2003

This paper discusses the contribution and value of research into human resource management issues as they affect auditors and audit firms, and to identify areas for future research. The contribution and areas for future research are identified in terms of four areas, namely career development, staffing patterns, the multi‐disciplinery global firm, and the management structure and practice as they relate to audit firms. This is followed by a discussion about the value of this research. In the conclusion the paper argues for future research to adopt a greater sociological and organizational perspective, including studies which work shadow auditors and audit teams, and longitudinal studies.
Streamflow and Water Well Responses to Earthquakes
Authors: Montgomery David R. , Manga Michael
Published: June 2003

Earthquake-induced crustal deformation and ground shaking can alter stream flow and water levels in wells through consolidation of surficial deposits, fracturing of solid rocks, aquifer deformation, and the clearing of fracture-filling material. Although local conditions affect the type and amplitude of response, a compilation of reported observations of hydrological response to earthquakes indicates that the maximum distance to which changes in stream flow and water levels in wells have been reported is related to earthquake magnitude. Detectable streamflow changes occur in areas within tens to hundreds of kilometers of the epicenter, whereas changes in groundwater levels in wells can occur hundreds to thousands of kilometers from earthquake epicenters.
Facilitation of Spinal NMDA Receptor Currents by Spillover of Synaptically Released Glycine
Authors: Ahmadi Seifollah , Muth-Selbach Uta , Lauterbach Andreas , Lipfert Peter , Neuhuber Winfried L. , Zeilhofer Hanns Ulrich
Published: June 2003

In the mammalian CNS,
N
-methyl-D-aspartate (NMDA) receptors serve prominent roles in many physiological and pathophysiological processes including pain transmission. For full activation, NMDA receptors require the binding of glycine. It is not known whether the brain uses changes in extracellular glycine to modulate synaptic NMDA responses. Here, we show that synaptically released glycine facilitates NMDA receptor currents in the superficial dorsal horn, an area critically involved in pain processing. During high presynaptic activity, glycine released from inhibitory interneurons escapes the synaptic cleft and reaches nearby NMDA receptors by so-called spillover. In vivo, this process may contribute to the development ofinflammatory hyperalgesia.
Biosynthesis of the Food and Cosmetic Plant Pigment Bixin (Annatto)
Authors: Bouvier Florence , Dogbo Odette , Camara Bilal
Published: June 2003

Bixin, also known as annatto, is a seed-specific pigment widely used in foods and cosmetics since pre-Columbian times. We show that three genes from
Bixa orellana
, native to tropical America, govern bixin biosynthesis. These genes code for lycopene cleavage dioxygenase, bixin aldehyde dehydrogenase, and norbixin carboxyl methyltransferase, which catalyze the sequential conversion of lycopene into bixin. Introduction of these three genes in
Escherichia coli
engineered to produce lycopene induced bixin synthesis, thus expanding the supply of this economically important plant product.
Raney Ni-Sn Catalyst for H
2
Production from Biomass-Derived Hydrocarbons
Authors: Huber G. W. , Shabaker J. W. , Dumesic J. A.
Published: June 2003

Hydrogen (H
2
) was produced by aqueous-phase reforming of biomass-derived oxygenated hydrocarbons at temperatures near 500 kelvin over a tin-promoted Raney-nickel catalyst. The performance of this non–precious metal catalyst compares favorably with that of platinum-based catalysts for production of hydrogen from ethylene glycol, glycerol, and sorbitol. The addition of tin to nickel decreases the rate of methane formation from C-O bond cleavage while maintaining the high rates of C-C bond cleavage required for hydrogen formation.
Lattice Animals and Self-Organized Criticality
Authors: Shahverdian A. Yu
Published: June 2003

The paper considers one model of SOC close to BTW and slider blocks models. In addition, it introduces an additional time parameter and imposes special restrictions on the avalanche geometrical structure. The generalization and modification of the avalanche's concept allows us to apply H. Weyl's theorem in the dynamical system theory so as to obtain the strong and exact results in this area. We introduce some combinatorial characteristic of clusters and use it as a tool for estimating the frequency of the avalanches. The results obtained give the asymptotically exact expressions for the asymptotical frequency as well as two special types of such extended avalanches. In some special cases, they reduce the determination of the frequency of the avalanches to combinatorial enumerative problem for lattice animals on the d-dimensional torus. The other two results are related to the one-dimensional model and establish the connection between the SOC and the theory of number partitions.
UV-Induced Fractal Surfaces
Authors: Beleznai Cs. , Vajtai R. , Nánai L.
Published: June 2003

Poly (tetrafluorethylene) and polyimide samples were irradiated by a pulsed laser source at 308 nm and the resulting surface morphology was investigated. The photoablated surfaces show a strong dependence on the optical and structural parameters of the polymers. The roughness of the fractal surfaces has been characterized by means of calculating their fractal dimensions and the results are interpreted as a function of the polymer physical parameters.
Multifractality in High Energy Collisions
Authors: Blažek Mikuláš
Published: June 2003

With increasing energy of nuclear collisions, several statistical distributions of produced particles show changes in shape. This also concerns the scaling indices which characterize multifractality in the observed particle density distributions. In the present contribution, the self-similar processes governing that multifractality are described in more detail. It is shown especially that the corresponding extended fundamental equation reproduces, with very good accuracy, the data resulting from the oxygen beam at 60 and 200 A GeV colliding with the emulsion nuclei. The approximate description of the quantities characterizing scaling properties near the quark-gluon phase transition is discussed too.
Lack of NB1 GP (CD177/HNA-2a) gene transcription in NB1 GP- neutrophils from NB1 GP–expressing individuals and association of low expression with NB1 gene polymorphisms
Authors: Wolff Jens , Brendel Cornelia , Fink Ludger , Bohle Rainer M. , Kissel Karin , Bux Juergen
Published: June 2003

The human neutrophil NB1 glycoprotein (NB1 GP, HNA-2a, CD177) has gained clinical importance for being involved in pulmonary transfusion reactions and immune neutropenias. The NB1 GP shows the unique feature of being expressed only on a neutrophil subpopulation. Recently, we identified splicing defects responsible for an NB1 GP deficiency. In this study, we have investigated the molecular basis of the heterogeneous expression of NB1 GP by separating the 2 neutrophil subpopulations using immunofluorescence followed by single-cell picking or by fluorescence-activated cell sorter. We found a lack of NB1 mRNA in the NB1 GP- cells that remained constant even after granulocyte colony-stimulating factor (G-CSF) administration. Comparing the cDNA sequences of donors with a large (> 60%) and those with a small (< 40%) NB1 GP–expressing subpopulation, we found 6 polymorphisms. Of the 6, 3 were significantly associated with a small NB1 GP–expressing subpopulation, indicating a genetic basis for NB1 GP nonexpression.
A simple method to predict response to immunosuppressive therapy in patients with myelodysplastic syndrome
Authors: Saunthararajah Yogen , Nakamura Ryotaro , Wesley Robert , Wang Qiong J. , Barrett A. John
Published: June 2003

Immunosuppression with antithymocyte globulin (ATG) or cyclosporine (CSA) can be used to treat the cytopenia associated with myelodysplastic syndrome (MDS). Previously, we identified HLA-DR15, younger age, and shorter duration of red cell transfusion dependence as pretreatment variables that correlate significantly with a response. Using these pretreatment variables we have devised a simple method to prospectively identify patients with low or high probabilities of response to immunosuppression. The ability of this system to predict response was confirmed in a separate cohort of 23 patients with MDS treated with immunosuppression.
Childhood bereavement services: a survey of UK provision
Authors: Rolls L , Payne S
Published: June 2003

The purpose of the study was to identify the location, range and type of childhood bereavement service provision in the UK. A questionnaire was mailed to 127 services who were either solely dedicated to childhood bereavement or who offered a service within the range of work of a host organization and for which there was a supporting organizational structure. Responses were received from 108 services (a response rate of 85%). The findings identified that 85% of childhood bereavement services are located in the voluntary sector; 14% are dedicated childhood bereavement services, while 86% are offered as part of a host organization. Forty-four per cent of host organizations are hospices. The majority of services (73%) relied on both paid and unpaid staff, with 11% relying entirely on paid staff and 14% of services relying entirely on unpaid staff. The interventions offered ranged from individual family work (86%), individual child work (62%), groupwork with families (53%) and groupwork with children (45%). In addition, services offered prebereavement support (64%), a ’drop-inflservice (17%), information and advice (95%), training (32%) and the provision of resources (88%). As well as offering a service to children and their families, 74% of childhood bereavement services provided a service to ’secondary users‘, such as schools (66%), the emergency services (28%) and other professionals (63%). In terms of funding, 12% of services relied solely on external sources of funding, including donations, legacies, revenue from the host organization or grants, while 12% of services relied solely on internal sources of funding, including fundraising and training. The majority of services (73%), however, gained income from a range of sources. The study identifies the diversity of provision that has implications for the evaluation of childhood bereavement services.
Autobiographical narrative and psychiatry
Authors: Oyebode Femi
Published: June 2003

This paper addresses how mental illness and psychiatry are presented in autobiographical narratives. The richness of clinical psychopathology unmediated by the expectations of psychiatry is described. The rituals of psychiatry, the importance of the personal relationships between patients and clinicians, and the subjective beliefs of people about mental illness are explored.
The patient within — psychopathology in the helping professions
Authors: Tillett Richard
Published: June 2003

Doctors, like other health professionals, show increased rates of psychological morbidity, including anxiety, depression, suicide, drug and alcohol misuse and professional exhaustion (burnout). This might be due in part to the pressures of clinical work, but might also reflect Malan's ‘helping profession syndrome’, in which an individual chooses, usually unconsciously, to work as a carer as a response to personal vulnerability, or ‘the patient within’. This paper reviews the literature relating to the complex relationship that health professionals have with their work role, discusses the implications for the profession, and proposes areas of prophylactic or remedial action.
Current issues in child and adolescent psychopharmacology. Part 2: Anxiety and obsessive—compulsive disorders, autism, Tourette's and schizophrenia
Authors: Coghill Dave
Published: June 2003

This paper reviews the evidence base supporting the use of pharmacological treatments for child and adolescent psychiatric disorders. Recent advances in knowledge are highlighted, with some of the controversies. New evidence supports a role for selective serotonin reuptake inhibitors in the treatment of anxiety disorders and obsessive–compulsive disorder. Educational and behavioural approaches remain the mainstay of treatment for children and adolescents with autism, but there is evidence that adjunctive medication may be effective. Atypical antipsychotics have been investigated in the treatment of Tourette syndrome and early-onset schizophrenia. Many questions remain unanswered and further research is needed in all areas of paediatric psychopharmacology.
‘Teaching the teachers' in psychiatry
Authors: Vassilas Christopher A. , Brown Nicholas , Wall David , Womersley Hester
Published: June 2003

The teaching of medical skills to medical students and to other doctors is a skill in itself. The traditional ‘apprenticeship’ system of learning within medicine is now known to be inefficient and flawed, in both the UK and in other countries where it has been scrutinised. This article sets out guiding principles to help doctors set up ‘teaching the teachers' courses, which teach the skills of teaching. Psychiatrists at all grades, from senior house officer up to consultant, need some teaching skills, and the authors outline how to plan a course, determine the needs of potential learners and set its objectives and content. Guidance is given on some of the opportunities that are available to obtain formal qualifications in medical education.
Psychological debriefing is a waste of time
Authors: Wessely S. , Deahl M.
Published: June 2003

People who experience serious traumatic events may become distressed and are at risk of developing psychological illness. Because of the perceived need to ease the distress and to prevent chronicity, various forms of psychological therapy have been deployed. One such therapy is psychological debriefing. Some claim that it is helpful, others claim it may not do any good but at least it does no harm, but still others claim that it increases the risk of people developing long-term psychological symptoms following a traumatic event. Statutory agencies, charities and commercial organisations offer their services to victims following traumatic events. Fearing litigation, some companies require their employees to undergo debriefing following certain incidents. But is psychological debriefing the right treatment? Is it cost-effective? And what of the concerns that it may lead to long-term problems? Could litigation be joined because of exposure to psychological debriefing? We asked two experts who have published widely on the subject – Professor Simon Wessely and Professor Martin Deahl – to debate the proposition that psychological debriefing is a waste of time.
Interface between authorship, industry and science in the domain of therapeutics
Authors: Healy David , Cattell Dinah
Published: June 2003

Background

Changes in the character of medical authorship.

Aims

To compare the impact of industry-linked and non-industry linked articles.

Method

We compared articles on sertraline being coordinated by a medical writing agency with articles not coordinated in this way. We calculated numbers of Medline-listed articles per author, journal impactfactors, literature profiles and citation rates of both sets of articles.

Results

Non-agency-linked articles on sertraline had an average of 2.95 authors per article, a mean length of 3.4 pages, a mean Medline listing of 37 articles per author (95% CI 27–47) and a mean literature profile of 283 per article (95% CI 130–435). Agency-linked articles on sertraline had an average of 6.6 authors per article, a mean length of 10.7 pages, a mean Medline listing of 70 articles per author (95% CI 62–79) and a mean literature profile of 1839 per article (95% CI 1076-2602). The citation rate for agency articles was 20.2 (95% CI 13.4–27.0) and for non-agency articles it was 3.7 (95% CI 3.3–8.1).

Conclusions

The literature profiles and citation rates of industry-linked and non-industry-linked articles differ. The emerging style of authorship in industry-linked articles can deliver good-quality articles, but it raises concerns for the scientific base of therapeutics.
Molecular Tumor Markers in the Blood: Early Prediction of Disease Outcome in Melanoma Patients Treated With a Melanoma Vaccine
Authors: Wascher Robert A. , Morton Donald L. , Kuo Christine , Elashoff Robert M. , Wang He-Jing , Gerami Mehri , Hoon Dave S.B.
Published: June 2003

Purpose: Patients with American Joint Committee on Cancer (AJCC) stage III melanoma are at high risk of recurrence and death. We hypothesized that a multiple-marker reverse transcriptase polymerase chain reaction (MM-RT-PCR) blood assay could predict, early in the course of therapy, those patients destined to experience treatment failure with a melanoma vaccine (MV) previously shown to improve survival in a phase II clinical trial.

Patients and Methods: After complete surgical resection, prospectively collected cryopreserved peripheral-blood lymphocyte specimens (n = 90) from the serial bleeds of 30 patients with AJCC stage III melanoma were studied by MM-RT-PCR, using the markers tyrosinase, melanoma antigen recognized by T cells-1 (MART-1), and universal melanoma antigen gene-A (uMAG-A). All patients were enrolled in a phase II MV trial during the period of blood draws, and were selected for this study in a blinded fashion. Median duration of clinical follow-up was 74 months for the 13 survivors and 11 months for the 17 nonsurvivors.

Results: The presence of at least one melanoma-specific RT-PCR marker was associated with an increased risk of disease recurrence (risk rate, 3.12; P = .02) and decreased risk of survival (relative rate, 2.62; P = .0496) by multivariate analysis.

Conclusion: MM-RT-PCR of the blood provided early prediction of subsequent disease recurrence and death in clinically disease-free AJCC stage III melanoma patients enrolled in a MV phase II trial. On the basis of the results of this pilot study, the MM-RT-PCR blood assay should be considered as a clinically important monitoring tool for assessing patient response to adjuvant therapy, and in the surveillance of clinically disease-free patients for the earliest signs of recurrence.
Randomized Phase II Study of Temozolomide Given Every 8 Hours or Daily With Either Interferon Alfa-2b or Thalidomide in Metastatic Malignant Melanoma
Authors: Danson S. , Lorigan P. , Arance A. , Clamp A. , Ranson M. , Hodgetts J. , Lomax L. , Ashcroft L. , Thatcher N. , Middleton M.R.
Published: June 2003

Purpose: Temozolomide is an imidazotetrazine with a mechanism of action similar to dacarbazine and equivalent activity in melanoma. It is well tolerated and is a candidate for combination chemotherapy and schedule manipulation. In this study, we combined temozolomide with interferon alfa-2b and, separately, with thalidomide, and we administered temozolomide alone in a compressed schedule. The objectives of this randomized phase II, two-center study were to determine response rates, overall survival, and tolerability of the regimens in patients with advanced metastatic melanoma.

Patients and Methods: One hundred eighty-one patients with metastatic melanoma were randomly assigned to receive up to six 4-weekly cycles consisting of temozolomide 200 mg/m2 every 8 hours for five doses, or temozolomide 200 mg/m2 daily for days 1 to 5 plus interferon alfa-2b 5 MU (million International Units) subcutaneously three times a week, or temozolomide 150 mg/m2 (increased after one cycle to 200 mg/m2) daily on days 1 to 5 plus thalidomide 100 mg daily days 1 to 28.

Results: The treatment arms were well balanced for known prognostic factors. Median survival was 5.3 months for 8-hourly temozolomide, 7.7 months for temozolomide/interferon, and 7.3 months for temozolomide/thalidomide; and 1-year survivals were 18%, 26%, and 24%, respectively. Response or disease stabilization occurred in 20% of patients (95% confidence interval [CI], 10% to 33%) given 8-hourly temozolomide, 21% (95% CI, 12% to 33%) given temozolomide/interferon, and 25% (95% CI, 15% to 38%) given temozolomide/thalidomide. Grade 3 or 4 nonhematologic toxicities were similar in each arm except for infection, which was more frequent with 8-hourly temozolomide. There were fewer instances of grade 3 or 4 myelotoxicity with temozolomide/thalidomide.

Conclusion: Of the three regimens tested, the combination of temozolomide and thalidomide seems the most promising for future study.
The pattern of neuroblast formation, mitotic domains and proneural gene expression during early brain development inDrosophila
Authors: Urbach Rolf , Schnabel Ralf , Technau Gerhard M.
Published: June 2003

In the Drosophila embryo, studies on CNS development have so far mainly focused on the relatively simply structured ventral nerve cord. In the trunk, proneural genes become expressed in small cell clusters at specific positions of the ventral neuroectoderm. A lateral inhibition process mediated by the neurogenic genes ensures that only one cell within each proneural cluster delaminates as a neural stem cell (neuroblast). Thus, a fixed number of neuroblasts is formed, according to a stereotypical spatiotemporal and segmentally repeated pattern, each subsequently generating a specific cell lineage. Owing to higher complexity and hidden segmental organisation, the mechanisms underlying the development of the brain are much less understood. In order to pave the way towards gaining deeper insight into these mechanisms,we have undertaken a comprehensive survey of early brain development until embryonic stage 11, when all brain neuroblasts have formed. We describe the complete spatiotemporal pattern of formation of about 100 brain neuroblasts on either side building the trito-, deuto- and protocerebrum. Using 4D-microscopy, we have uncovered various modes of neuroblast formation that are related to specific mitotic domains of the procephalic neuroectoderm. Furthermore, a detailed description is provided of the dynamic expression patterns of proneural genes (achaete, scute, lethal of scute, atonal)in the procephalic neuroectoderm and the individual neuroblasts. Finally, we present direct evidence that, in contrast to the trunk, adjacent cells within specific domains of the procephalic neuroectoderm develop as neuroblasts,indicating that mechanisms controlling neuroblast formation differ between head and trunk.
TheDrosophilabZIP transcription factor Vrille is involved in hair and cell growth
Authors: Szuplewski Sébastien , Kottler Benjamin , Terracol Régine
Published: June 2003

Vri is closely related to bZIP transcription factors involved in growth or cell death. vri clonal and overexpression analyses revealed defects at the cellular level. vri clones in the adult cuticle contain smaller cells with atrophic bristles. The phenotypes are strictly cell autonomous. Clones induced in the eye precursor cells lead to individuals with smaller eyes and reduced number of ommatidia with an abnormal morphology and shorter photoreceptor cell stalks. Overexpression of vri is anti-proliferative in embryonic dorsal epidermis and in imaginal discs, and induces apoptosis. On the wing surface, larger cells with multiple trichomes are observed, suggesting cytoskeletal defects. In salivary glands, vri overexpression leads to smaller cells and organs. We also show that vri is involved in locomotion and flight and interacts genetically with genes encoding actin-binding proteins. The phenotypes observed are consistent with the hypothesis that vri is required for normal cell growth and proliferation via the regulation of the actin cytoskeleton.