bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamical symmetry analysis of ionization and harmonic generation of atoms in bichromatic laser pulses
Authors: Fleischer Avner , Gupta Ashish Kumar , Moiseyev Nimrod
Published: March 2005

Recently the effect of the relative phase ϕ in a high‐intensity (∼1014 W/cm2) two‐color (bichromatic) CW laser with frequencies ω and 2ω on the high‐order harmonic generation (HHG) was studied within the framework of the non‐Hermitian quantum mechanics (NHQM) [Phys Rev A 2004, 69, 043404/1]. Here we emphasize the study of symmetries in bichromatic HHG spectra within the framework of the conventional Hermitian QM, and in particular by taking the duration of the laser pulse into consideration (an effect that has not been included in the non‐Hermitian studies due to the time asymmetry problem in NHQM). The phase dependence of HHG and intense‐field ionization probability in a 1D Xe atom with symmetric field‐free potential and symmetric initial wave function were studied numerically and analytically. From simulations based on a single‐particle response it can be seen that the HHG spectra is symmetric with respect to inversion in the relative phase between the two colors ϕ only if ionization is forbidden in the system and the laser pulse is an adiabatic one. The HHG spectra is symmetric with respect to a π‐shift in ϕ whenever the laser pulse is an adiabatic one, either for bound or open (ionized) systems. The ionization probability is symmetric both to inversion or π‐shift in ϕ; the component probabilities (right‐ and left‐ionization probabilities) have the same ϕ‐dependence, up to a shift of π. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Large first hyperpolarizabilities of substituted aniline oligomers
Authors: de A. Machado A. E. , da Gama A. A. S.
Published: March 2005

Substituted and nonsubstituted aniline oligomers were theoretically investigated. Aniline oligomers with a dicyanoethenyl acceptor group attached at a terminal site of each known structure (emeraldine, pernigraniline, and leucoemeraldine forms), contributing to obtain large first hyperpolarizabilities. The effect of oligomer size on the nonlinear responses was also investigated by considering oligomers with different chain length (tetramers and octamers). The magnitudes of β calculated for the functionalized and nonfunctionalized octamers were larger than for the tetramers and their substituted oligomers. The substituted pernigraniline octamer presented the largest β value among the investigated aniline oligomers. The results of the AM1/TDHF calculations suggest that these aniline‐based materials can be good candidates for second‐order nonlinear optical materials. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Generalized formulation of quantum and classical crystallography using Green's functions
Authors: Karabiyik Hasan , Aygün Muhi̇tti̇n
Published: March 2005

Quantum crystallography is a methodology by which structural information about a crystalline material obtained from X‐ray crystallography is combined with quantum mechanical methods. The objective is to enhance the data obtained from the X‐ray diffraction experiment, which are related to the atomic structure of the crystal, and to predict the properties and efficacy of those chemical compounds from which the crystals are derived. One approach in quantum crystallography is to use a projector matrix with a normalized trace. In this approach, quantum mechanical parameters in the projector matrix are fit into crystallographic data. During this fitting, the properties of the projector matrix called idempotency and normalization are used. Throughout this implementation procedure, Clinton's iteration scheme has been used in addition to the least‐squares technique. The purpose of the present study is to generalize Clinton's iterative equations in quantum crystallography by means of single‐particle Green's functions with the aid of the equal atoms model in the theory of direct methods. Convergency characters of the novel iterative equations are discussed by the steepest descent procedure. Furthermore, whether the calculations are valid in nonorthogonal bases was also examined. The iteration schemes widely used in quantum crystallography have been generalized but, in addition, the generalized expressions relating to the phase determination procedure and the probabilities of the sign relations between the structure factors are obtained and discussed comprehensively. The phrase order of crystallography has been put forward as a new concept. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Atomic decomposition of identity: General formalism for population analysis and energy decomposition
Authors: Mayer I. , Hamza A.
Published: March 2005

The concept of “atomic resolution of identity” has been introduced, leading to a very simple general formalism for generating different decomposition schemes of molecular quantities. Thus, different population analysis and energy partitioning schemes can be treated as special cases of a common framework. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
HREELS, TPD and ESD study of electron‐induced decomposition of trimethylamine on Si(100) at 100 K
Authors: Lozano J. , Early D. , Craig J. H. , Wang P. W. , Kimberlin K. R.
Published: March 2005

The effects of 600 eV electron irradiation on adsorbed layers of trimethylamine (TMA) on a Si(100) surface at 100 K were studied using high‐resolution electron energy loss spectroscopy (HREELS), temperature programmed desorption (TPD), electron‐stimulated desorption (ESD) and x‐ray photoelectron spectroscopy (XPS). Experiments were performed at monolayer and higher coverages. The ESD results obtained on physisorbed TMA indicate electron‐induced decomposition of the parent molecule. The HREELS data also show cleavage of NC bonds on the chemisorbed layer of TMA and deposition of CHx groups on the surface, which is also supported by a dramatic enhancement of hydrogen desorption at 960 K following electron irradiation. This multiple‐step process is supported by ESD signal decay curves obtained during electron irradiation. Following electron irradiation of TMA/Si(100), the intensity of low temperature TPD peaks corresponding to TMA fragments decreases; however, the intensity of the mass 2 peak increases dramatically compared with the un‐irradiated surface. This is indicative of electron‐induced associative desorption of molecular hydrogen. The HREELS data from monolayer coverage of TMA on Si(100) after electron irradiation suggests the removal of CHx groups from the adsorbate layer and deposition of carbon and hydrogen on the surface. In the absence of physisorbed layers there is no indication of electron‐induced desorption of TMA fragments. Copyright © 2005 John Wiley & Sons, Ltd.
Nitrogen analysis using energetic ion beams
Authors: Jiang W. , Shutthanandan V. , Thevuthasan S. , Wang C. M. , Weber W. J.
Published: March 2005

As a special case of nuclear reaction analysis (NRA), nuclear elastic scattering analysis (or non‐Rutherford scattering analysis) is one of the important methods in ion beam analysis and is the preferred technique to analyze light elements in a heavy matrix. Compared with nuclear reaction, nuclear scattering usually has cross‐sections several orders of magnitude larger, which allows quantitative analysis of light elements in a quicker and more convenient manner. Similar to NRA, this method complements the analysis of widely used Rutherford backscattering spectrometry. In this study, the scattering cross‐sections for14N(p,p)14N and14N(α,α)14N at a laboratory angle of 150° are measured over energy regions from 2.480 to 3.774 MeV using an amorphous film of Si3N4on Si wafer. Examples for the analysis of lattice disorder on the nitrogen sublattice in Au2+‐irradiated GaN single crystals will be demonstrated. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis and characterization of silica sphere‐packing mesoporous materials
Authors: Roque‐Malherbe Rolando , Marquez Francisco
Published: March 2005

In the present study, using the Stobe–Fink–Bohn (SFB) method we synthesize and characterize silica sphere‐packing mesoporous materials. The SFB procedure was modified slightly to obtain materials with high specific surface area. The structure and essential features of the materials obtained were studied with the help of scanning electron microscopy and the analysis of isotherms of physical adsorption of N2 at 77 K. Some of the sphere‐packing materials obtained possess a relatively large specific surface area and the presence of a mesoporous structure within the silica spheres has been demonstrated; consequently, these materials could be used as adsorbents, catalysts and other high‐surface‐area and porosity‐related applications. Copyright © 2005 John Wiley & Sons, Ltd.
XPS and Raman spectroscopic characterization of LiMn2O4 spinels
Authors: Ramana C. V. , Massot M. , Julien C. M.
Published: March 2005

Surface analysis of lithium manganese oxides synthesized by the melt–impregnation method has been made by x‐ray photoelectron spectroscopy. These results revealed the change in the average oxidation state of Mn cations upon lithium substitution in Li1+δMn2−δO4 spinels. Studies of the local structure characterized by Raman scattering show the MnO bonding evolution as a function of the replacement of manganese cations. Modification in the trigonal distortion of MnO6 octahedra is evidenced by insertion of lithium ions into the octahedral holes of the [B2]O4 spinel framework. Copyright © 2005 John Wiley & Sons, Ltd.
Erosion rate variations during XPS sputter depth profiling of nanoporous films
Authors: Gaspar Daniel J. , Engelhard Mark H. , Henry Matthew C. , Baer Donald R.
Published: March 2005

Sputter depth profiling is commonly used to obtain valuable information regarding the three dimensional distribution of elements within a sample, and is one of the best ways to measure the composition of a buried interface or the uniformity of a thin film. X‐ray photoelectron spectroscopy (XPS) is one of the analysis tools often used in conjunction with ion beam erosion to obtain sputter depth profiles. However, to obtain accurate depth information it is often necessary to understand better the sputtering process for a specific materials system. Artifacts such as differential sputtering, varying sputter rates and ion beam‐induced chemistry are well known. Here, however, we present evidence from experiments on a porous thin film deposited on an Si wafer that relatively small chemical and/or structural changes in a nanoporous film can affect the rate of erosion measured during sputter depth profiling. Reproducible variations in sputter rate are found with chemical modification leading to compositional changes of the nanoporous thin film. The origin of the sputter rate changes is discussed with the aid of results obtained using Fourier transform infrared spectroscopy, profilometry, nuclear reaction analysis, electron microscopy and XPS‐based depth profiling. Copyright © 2005 John Wiley & Sons, Ltd.
The impact of beta‐adrenoreceptor gene polymorphisms on survival in patients with congestive heart failure*
Authors: de Groote Pascal , Lamblin Nicolas , Helbecque Nicole , Mouquet Frédéric , Mc Fadden Eugène , Hermant Xavier , Amouyel Philippe , Dallongeville Jean , Bauters Christophe
Published: March 2005

Objective:

Discordant results have been published regarding a possible association between beta‐adrenoreceptor (βAR) gene polymorphisms and survival in patients with congestive heart failure (CHF). The aim of the study was to analyze the impact of five functional βAR gene polymorphisms in patients with stable CHF.

Methods:

We prospectively studied 444 consecutive patients with CHF related to left ventricular systolic dysfunction. The β1ARSer49Gly, β1ARGly389Arg, β2AR Arg16Gly, β2AR Gln27Glu and β2AR Thr164Ile polymorphisms were determined. Patients underwent echocardiography, radionuclide angiography and a cardiopulmonary exercise test.

Results:

Mean age was 56.6±11.9 years old, left ventricular ejection fraction (LVEF) was 32±12%, and peak VO2 was 15.5±4.9 ml/min/kg or 63±18% of maximal predicted VO2. Most of the patients (95%) were receiving angiotensin converting enzyme inhibitors and 91% β‐blockers. There was no statistically significant differences between baseline characteristics among β1AR and β2AR genotypes. During a median follow‐up period of 1232 days, there were 110 cardiac‐related deaths and five urgent transplantations. Independent predictors of survival were percent (%) of maximal predicted VO2 (p<0.0001), age (p<0.0001), LVEF (p=0.004), creatinine (p=0.02) and atrial fibrillation (p=0.04). No βAR polymorphisms were associated with survival. However, patients with the combined β2ARGly16Gly/β2ARGln27Gln genotype, who express receptors highly sensitive to down‐regulation, had a significantly lower survival rate than patients with other genotypes but only in univariate analysis.

Conclusions:

In this prospective study, we found no association between five functional βAR polymorphisms and survival in patients with stable CHF. However, we demonstrated, only in univariate analysis, a possible association between the combined β2ARGly16Gly/β2ARGln27Gln genotype and survival.
Effects of nebivolol on left ventricular function in elderly patients with chronic heart failure: results of the ENECA study
Authors: Edes Istvan , Gasior Zbigniew , Wita Krystian
Published: March 2005

Aim

To examine the effect of the beta1‐selective beta‐blocker nebivolol, administered as add‐on therapy, on left ventricular function in 260 elderly patients (>65 years) with chronic heart failure (CHF).

Methods

The principal inclusion criteria were (1) NYHA class II–IV CHF and (2) a left ventricular ejection fraction (LVEF) ≤35%. The primary end‐point was the change in LVEF in response to nebivolol treatment for 8 months.

Results

Baseline LVEF values in the two groups were as follows: nebivolol 25.41±7.09% and control 26.41±5.55%. LVEF improved significantly (p=0.027) more in the nebivolol group (6.51±9.15%) than in the control group (3.97±9.20%), the relative improvement (percentage increase in the initial value) being 35.70±57.62% in the nebivolol group and 19.19±40.96% (p=0.008) in the placebo group. Examination of different subgroups did not reveal any heterogeneity in the effects of nebivolol treatment vs. placebo treatment. There were no significant differences between the nebivolol and placebo groups as concerns the changes in clinical status, quality of life, or safety parameters.

Conclusion

The findings of the ENECA study confirmed that nebivolol significantly improved cardiac function and proved to be safe and well tolerated in elderly patients with signs of CHF and an impaired LVEF.
Molecular mimicry may contribute to pathogenesis of ulcerative colitis
Authors: Kovvali Gopala , Das Kiron M.
Published: March 2005

Ulcerative colitis (UC) is a chronic inflammatory bowel disease with mucosal inflammation and ulceration of the colon. There seems to be no single etiological factor responsible for the onset of the disease. Autoimmunity has been emphasized in the pathogenesis of UC. Perinuclear anti‐neutrophil cytoplasmic antibodies (pANCA) are common in UC, and recently two major species of proteins immunoreactive to pANCA were detected in bacteria from the anaerobic libraries. This implicates colonic bacterial protein as a possible trigger for the disease‐associated immune response. Autoantibodies and T‐cell response against human tropomyosin isoform 5 (hTM5), an isoform predominantly expressed in colon epithelial cells, were demonstrated in patients with UC but not in Crohn's colitis. We identified two bacterial protein sequences in NCBI database that have regions of significant sequence homology with hTM5. Our hypothesis is that molecular mimicry may be responsible for the pathogenesis of UC.
Polarised distribution of the RNA‐binding protein Staufen in differentiated intestinal epithelial cells
Authors: Gautrey Hannah , McConnell Josie , Hall Judith , Hesketh John
Published: March 2005

mRNA localisation, as a mechanism for directing localised protein synthesis, plays a vital role in the functioning of certain cells, such as neurons and oocytes. Potentially this mechanism may also occur in polarised intestinal epithelial cells. Here we show that Staufen155, a protein involved in mRNA localisation and transport, is asymmetrically distributed in differentiated Caco‐2 intestinal epithelial cells and partly co‐localised with calnexin, a marker of the endoplasmic reticulum. The localisation to the apical region of the cell indicates that Staufen may be involved in localisation of transcripts to this domain.
Confinement and crowding effects on tryptophan synthase α2β2 complex
Authors: Pioselli Barbara , Bettati Stefano , Mozzarelli Andrea
Published: March 2005

Biological molecules experience in vivo a highly crowded environment. The investigation of the functional properties of the tryptophan synthase α2β2 complex either entrapped in wet nanoporous silica gels or in the presence of the crowding agents dextran 70 and ficoll 70 indicates that the rates of the conformational transitions associated to catalysis and regulation are reduced, and an open and less catalytically active conformation is stabilized.
Histone demethylation catalysed by LSD1 is a flavin‐dependent oxidative process
Authors: Forneris Federico , Binda Claudia , Vanoni Maria Antonietta , Mattevi Andrea , Battaglioli Elena
Published: March 2005

Lysine‐specific histone demethylase 1 (LSD1) is a very recently discovered enzyme which specifically removes methyl groups from Lys4 of histone 3. We have addressed the functional properties of the protein demonstrating that histone demethylation involves the flavin‐catalysed oxidation of the methylated lysine. The nature of the substrate that acts as the electron acceptor required to complete the catalytic cycle was investigated. LSD1 converts oxygen to hydrogen peroxide although this reactivity is not as pronounced as that of other flavin‐dependent oxidases. Our findings raise the possibility that in vivo LSD1 might not necessarily function as an oxidase, but it might use alternative electron acceptors.
Analysis of the domain properties of the novel cytochrome P450 RhF
Authors: Hunter Dominic J.B. , Roberts Gareth A. , Ost Tobias W.B. , White John H. , Müller Steffen , Turner Nicholas J. , Flitsch Sabine L. , Chapman Stephen K.
Published: March 2005

The properties of the heme, flavin mononucleotide (FMN) and FeS domains of P450 RhF, from Rhodococcus sp. NCIMB 9784, expressed separately and in combination are analysed. The nucleotide preference, imidazole binding and reduction potentials of the heme and FMN domains are unaltered by their separation. The intact enzyme is monomeric and the flavin is confirmed to be FMN. The two one‐electron reduction potentials of the FMN are −240 and −270 mV. The spectroscopic and thermodynamic properties of the FeS domain, masked in the intact enzyme, are revealed for the first time, confirming it as a 2Fe–2S ferredoxin with a reduction potential of −214 mV.
Induction of uteroglobin‐related protein 2 (Ugrp2) expression by EGF and TGFα
Authors: Yamada Atsushi , Kimura Shioko
Published: March 2005

Uteroglobin‐related protein 2 (UGRP2) is thought to play a role in inflammation and/or epithelial cell differentiation in the lung. Induction of Ugrp2 mRNA expression by epidermal growth factor (EGF) and transforming growth factor α was examined using mouse transformed lung Clara cell‐derived mtCC cells. The EGF‐induced increase of Ugrp2 occurred at the transcriptional level that required the EGF receptor and the activation of the ERK‐MAPK and phosphoinositide‐3 kinase pathways.
Holocene aridity and storm phases, Gulf and Atlantic coasts, USA
Authors: Otvos Ervin G.
Published: March 2005

A bottomland flora that prevailed between ∼9900 and 6000 cal yr B.P. in a North Carolina stream valley may not reflect a regionally much wetter Atlantic climate, coeval with record drought in the Great Plains region and assumed dry Gulf coastal conditions. Such conditions were inferred for 6000 ± 1000 yr ago when the Bermuda High may have consistently occupied summer positions far to the NE. Arid episodes coeval with the Little River local wet interval are known from eolian sediments and pollen spectra in the Atlantic and the Gulf coastal plain. For multiple reasons, the regional extent, intensity, and duration of coastal aridity and alternating wet phases and the Bermuda High positions are not yet adequately constrained. The climate and edaphic causes for the steadily growing predominance of southern pines over hardwoods, achieved between ∼8900 and 4200 cal yr B.P. at different sites at different times are similarly still unresolved. New data from Shelby Lake, AL, reconfirms that no credible field or other proxy evidence exists for a previously postulated “catastrophic Gulf hurricane phase” in the late Holocene.
Gehirn und Geist: Biologie und Psychologie auf der Suche nach dem ganzen Menschen
Authors: Markl Hubert
Published: March 2005

Zusammenfassung. Der Mensch-Tier-Vergleich hat eine lange vorwissenschaftliche (meist metaphorisch-allegorische) und eine weiterwirkende wissenschaftliche Tradition, die letztlich in der evolutionären, also genetischen Verwandtschaft von Tier und Mensch begründet ist. Zwar werden dadurch viele Grundstrukturen des menschlichen Verhaltens erklärbar, doch ist es noch wichtiger, den Blick auf das zu richten, was an Verhalten und seelischen Eigenschaften des Menschen einzigartig ist. Die wichtigste angeborene Disposition könnte es sein, dass genetische Anlagen den Menschen in zwar unvergleichlichem, aber selbst dann durchaus vergleichsweise zu bewertendem Grade lernfähig, lernoffen, damit aber auch von eigener Lernerfahrung und vor allem von sozialem Lernen und sozialer Belehrung abhängig gemacht haben. Was sein Verhalten betrifft, ist der Mensch bei Geburt ein ganz unfertiges Tier. Bewusstsein seiner selbst, seiner Gefühle und seiner Gedanken, sowie entsprechende Bewusstseinszuschreibung und Einfühlungsvermögen in Empfindungen und Absichten anderer - menschlicher wie tierischer - Verhaltenspartner, sowie symbolisch-syntaktische Sprache, die beides zu reflektieren und mitzuteilen erlaubt, schaffen eine neue, geistige Welt, ohne deshalb die Rahmenbedingungen der Naturgesetze zu verlassen oder außer Kraft zu setzen. Freier Wille als die Fähigkeit in den Grenzen der Naturgesetze nach eigener Überlegung Entscheidungen zu treffen, muss den physischen Leistungsbedingungen des Gehirns nicht widersprechen: es ist die bewusste Reflektion über Wahlmöglichkeiten des Verhaltens, wie sie ihre Gehirne bereits unseren Tiervorfahren ermöglichten.
Das ALS-Depressionsinventar (ADI):
Authors: Kübler Andrea , Winter Susanne , Kaiser Jochen , Birbaumer Niels , Hautzinger Martin
Published: March 2005

Zusammenfassung. Theoretischer Hintergrund: Bei der amyotrophen Lateralsklerose (ALS) handelt es sich um eine fortschreitende degenerative Erkrankung, die zu vollständigem motorischen Funktionsausfall führen kann. Depressive Stimmung bei ALS-Patienten wirkt sich verkürzend auf die verbleibende Lebensspanne aus. Zur quantitativen Erfassung von Depression bei ALS-Patienten werden Fragebögen verwendet, die die spezifische Situation der zunehmenden körperlichen Beeinträchtigung bis hin zur vollständigen Lähmung und künstlicher Ernährung und Beatmung nicht berücksichtigen. Fragestellung: Die Entwicklung eines speziell auf diese Patientengruppe ausgerichteten Inventars zur Messung depressiver Symptomatik. Methode: Das neu entworfene Inventar wurde gesunden Personen (93), ALS-Patienten (76) und depressiven Patienten (56) vorgelegt. Anhand der Ergebnisse wurde das ursprüngliche Inventar auf 12 Items reduziert (ADI-12). Ergebnis: 75% der ALS-Patienten wiesen depressive Symptome auf. Patienten mit ALS waren signifikant weniger depressiv als Patienten mit Depression. Schlussfolgerungen: Bei ALS-Patienten ist mit depressiver Verstimmung zu rechnen. Mit dem ADI-12 kann Depression auch noch bei schwerstbeeinträchtigten ALS-Patienten gemessen werden.
Das “Systemisch Orientierte Erhebungsinventar“ im Vergleich zur intuitiv-unstrukturierten Exploration
Authors: Wiesflecker Sabine , Kubinger Klaus D.
Published: March 2005

Zusammenfassung. Theoretischer Hintergrund: Etlichen strukturierten Anamnesefragebogen bzw. -leitfäden wurde unlängst ein Gesprächsleitfaden zur psychologischen Anamneseerhebung bei Kindern und Jugendlichen, der auf den Grundlagen der Systemischen Therapie aufbaut, zur Seite gestellt. Fragestellung: Es geht um den Informationsbeitrag innerhalb einer psychologischen Untersuchung den das Systemisch Orientierte Erhebungsinventar von Kubinger (2003) im Vergleich zu einem “intuitiven-unstrukturierten“ Anamnesegespräch, wie es vor allem von wenig routinierten Praktiker(inne)n geführt wird. Methode: Die Untersuchungsmethode war ein Experiment, in dem mit Fallrekonstruktionen gearbeitet wurde, die jeweils mehrmals unter zwei verschiedenen experimentellen Bedingungen von insgesamt 10 Rollenspielern als angeblichen Klienten verwirklicht wurden. 20 Psychologiestudierende führten die entsprechenden Erstgespräche durch. Ergebnisse: Hinsichtlich der Validität laut Anzahl der für die Fallbehandlung relevanten Informationen sowie hinsichtlich der Ökonomie laut (geringer) Anzahl der für die Fallbehandlung irrelevanten Informationen ist das Systemisch Orientierte Erhebungsinventar der “intuitiv-unstrukturierten“ Gesprächsführung eindeutig überlegen. Schlussfolgerungen: Insbesondere für Unroutinierte ist beim Erstgespräch die Anwendung des Systemisch Orientierten Erhebungsinventars einer “intuitiven-unstrukturierten“ Gesprächsführung vorzuziehen.
On the singularity problem of the elastic‐gravitational dislocation theory applied to plane‐Earth models
Authors: Wang Rongjiang
Published: March 2005

The Earth's gravity field may significantly modify static deformations of large earthquakes. In the elastic‐gravitational dislocation theory, which was first published in the early 1980s, the gravity effect is taken into account by including a constant external gravity in plane‐Earth models. When using this theory, however, the response functions of the models exhibit singularities below a critical wave number, if the models contain an infinite compressible half space medium. Furthermore, the previous algorithm treated these singularities in an incorrect mathematical way. It is shown here that the boundary value problem for such plane‐Earth models is unsolvable at all for the low wave number range because of the unstable initial state of the models used. This study clarifies the role and differences played by unsolvability and instability and suggests a consistent way to solve the problem.
Variations in the diurnal character of tropical cyclone wind speeds
Authors: Cerveny Randall S. , Balling Robert C.
Published: March 2005

A significant decline in diurnal temperature range (DTR) is identified along the Atlantic seaboard. Recent studies suggest that DTR changes demonstrate a human‐created weekly cycle and may therefore be anthropogenic. In this study, we address whether there is a change in the diurnal variation in Tropical Cyclone (TC) wind speeds that is consistent with the DTR trend over land. Our analysis of 34 years of TC activity reveals variations such that the difference between day and night wind speeds of TCs has decreased over time. Our work gives limited support to the contention that TC diurnal wind speed differences are thermally driven and, hence, warmer night temperatures (a smaller DTR over time) are leading to stronger nighttime winds over time. Our study initiates investigation of potential influences of climate changes (such as DTR) on secondary climatic phenomena.
CaSiO3 perovskite at lower mantle pressures
Authors: Caracas R. , Wentzcovitch R. , Price G. David , Brodholt J.
Published: March 2005

We investigate by first‐principles the structural behavior of CaSiO3 perovskite up to lower mantle pressures. We confirm that the cubic perovskite modification is unstable at all pressures. The zero Kelvin structure is stabilized by SiO6 octahedral rotations that lower the symmetry to tetragonal, orthorhombic, rhombohedral, or to a cubic supercell. The resulting structures have comparable energies and equation of state parameters. This suggests that relatively small deviatoric/shear stresses might induce phase transformations between these various structures softening some elastic moduli, primarily the shear modulus. The seismic signature accompanying a local increase in CaSiO3 content should be a positive density anomaly and a negative VS anomaly.
Radial evolution of cross helicity in high‐latitude solar wind
Authors: Breech B. , Matthaeus W. H. , Minnie J. , Oughton S. , Parhi S. , Bieber J. W. , Bavassano B.
Published: March 2005

We employ a turbulence transport theory to explain the high‐latitude radial evolution of cross helicity, or Alfvénicity, observed by the Ulysses spacecraft. Evolution is slower than at low latitudes due to weakened shear driving.
Finding realistic dike models from interferometric synthetic aperture radar data: The February 2000 eruption at Piton de la Fournaise
Authors: Fukushima Y. , Cayol V. , Durand P.
Published: March 2005

Dike intrusions often cause complex ground displacements that are not sufficiently explained by simple analytical models. We develop a method to find complex and realistic dike geometries and overpressures from interferometric synthetic aperture radar (InSAR) data. This method is based on a combination of a boundary element method with realistic topography and a neighborhood algorithm inversion. Dike model geometry is roughly a quadrangle with its top reaching the ground. The inversion has two stages: search and appraisal. The appraisal stage involves calculations of model marginal probability density functions using misfit values calculated during the search stage. The misfit function takes into account the variance and correlation of data noise. Synthetic tests show that a model is successfully retrieved within predicted narrow confidence intervals. We apply the method on InSAR data of the February 2000 flank eruption at Piton de la Fournaise and get a trapezoid dike dipping seaward (61.0°–67.3°) with its bottom passing 800–1000 m beneath the summit. A model with a basal slip plane does not better explain observed asymmetric displacements, and thus this asymmetry is solely attributed to the dipping dike. The dike lies above a narrow band of preeruption seismicity, suggesting that lateral magma propagation occurred. Neglecting topography results in poor modeling at depth and in overestimations of overpressure (or opening), height (both about 30%), and volume (about 20%).
Earthquake slip distribution: A statistical model
Authors: Kagan Yan Y.
Published: March 2005

The purpose of this paper is to interpret slip statistics in a framework of extended earthquake sources. We first discuss deformation pattern of the Earth's surface from earthquakes and suggest that continuum versus block motion controversy can be reconciled by a model of the fractal distribution of seismic sources. We consider earthquake slip statistical distributions as they can be inferred from seismic moment‐frequency relations and geometrical scaling for earthquakes. Using various assumptions on temporal earthquake occurrence, these distributions are synthesized to evaluate the accuracy of geologic fault slip determinations and to estimate uncertainties in long‐term earthquake patterns based on paleoseismic data. Because the seismic moment distribution is a power law (Pareto), a major part of the total seismic moment is released by major earthquakes,M≥ 1019.5N m (moment magnitudem≥ 7); for these large earthquakes the rupture is confined to the upper brittle crust layer. We review the various moment‐frequency and earthquake scaling relationships and apply them to infer the slip distribution at area‐ and site‐specific regions. Simulating the seismic moment and strain accumulation process demonstrates that some synthetics can be interpreted as examples of a quasiperiodic sequence. We demonstrate the application of the derived slip statistical relations by analyzing the slip distribution and history of the San Andreas fault at Wrightwood, California.
Multicycle dynamics of nonplanar strike‐slip faults
Authors: Duan Benchun , Oglesby David D.
Published: March 2005

We perform two‐dimensional dynamic models of strike‐slip faults with a change in strike (a bend) over multiple earthquake cycles to examine the long‐term effects of nonplanar fault geometry. A viscoelastic model (a proxy for off‐fault deformation and tectonic loading) is introduced for the interseismic process to avoid pathological stress buildup around the bend. A finite element method with an elastodynamic model is used to simulate dynamic earthquake ruptures. We find that stresses near the bend differ strongly from the regional stress field and that the fault develops a relatively steady state in which the stress level and the event pattern on the fault are stable. Reduced normal stress on the dilatational side and increased normal stress on the compressive side of the bend during dynamic ruptures result in the bend serving as an initiation and/or a termination point(s) for rupture. Typical events on such a fault consist of two classes: unilateral events that rupture only the favorable segment and bilateral events that rupture the favorable segment and part of or the entire unfavorable segment. In the latter class of events, a time delay in rupture around the bend results from a high yield stress on the compressive side of the bend. Other effects of the bent fault geometry include higher displacement on the inward wall than on the outward wall, higher slip on the more favorable segment than on the less favorable segment, and a large slip velocity on the compressive side of the bend.
Life history of an anticyclonic eddy
Authors: Sangrà P. , Pelegrí J. L. , Hernández‐Guerra A. , Arregui Igor , Martín J. M. , Marrero‐Díaz A. , Martínez A. , Ratsimandresy A. W. , Rodríguez‐Santana A.
Published: March 2005

We use the trajectory of three buoys dragged below the surface mixed layer, together with sea surface temperature imagery, to examine the evolution of an anticyclonic warm‐core eddy since its generation by the Canary Islands. Two buoys remain within the eddy during some 100 days, and the third one remains almost 200 days, while drifting southwestward up to 500 km with the mean Canary Current. The eddy merges with several younger anticyclonic and cyclonic eddies, in each occasion, suffering substantial changes. The eddy core, defined as a region with near‐solid‐body‐type rotation and radial convergence, initially occupies the whole eddy. After interacting with another vortex the inner core markedly slows down, although it continues displaying radial convergence and relatively small radial oscillations, and an uncoupled outer ring is formed or enhanced, which revolves even more slowly and displays large radial fluctuations. The vortex extensive life is consistent with its inertially stable character and observations of radial convergence. A very simple model of vortex merging, where cylinders fuse conserving mass and angular momentum, gives fair results. The observations suggest that the eddy changes, as the result of its own slow evolution and sporadic mixing events, from a young stage, where the core retains its vorticity and occupies most of the eddy, through a mature stage, where the eddy has a reduced inner core and a slowly revolving outer ring, to a decay stage, where the vorticity maximum is substantially reduced.
Observed positive feedback between the NAO and the North Atlantic SSTA tripole
Authors: Pan Lin‐Lin
Published: March 2005

NCEP‐NCAR reanalysis data from 1948 to 2001 are used to examine the relationship between the North Atlantic Oscillation (NAO) and the North Atlantic sea surface temperature anomaly (SSTA) tripole. It is demonstrated that the atmospheric anomalies associated with NAO produce tripole‐like sea surface temperature (SST) anomalies; in turn, the SSTA tripole produces NAO‐like atmospheric anomalies. Therefore, a positive feedback between the NAO and the SSTA tripole is suggested. The results are statistically significant; they clarify prior uncertainties associated with the relationship between the NAO and the North Atlantic SSTA tripole.
Trypanothione reductase from the human parasiteEntamoeba histolytica: a new drug target
Authors: Tamayo Elsa María , Iturbe Angélica , Hernández Eva , Hurtado Gerardo , De Lourdes Gutiérrez‐X. María , Rosales José Luis , Woolery Mathew , Ondarza Raúl N.
Published: March 2005

Although there is a general agreement that the protistEntamoeba histolyticalacks glutathione, it has been a matter of dispute as to whether this human parasite contains the glutathione derivative known as trypanothione. In the present study, we describe a gene for the TR (trypanothione reductase) obtained fromE. histolyticaby PCR amplification of its DNA. After Northern‐blot analysis, the radiolabelled DNA probe fromTrypanosoma cruzihybridizes with the total RNA ofEntamoeba, showing that the TR gene is expressed as mRNA. We have demonstrated the presence of the NADPH‐dependent TR activityin vitrowith partially purified extracts and showed also that the thiol‐bimane compound isolated and purified fromE. histolyticatrophozoites, unequivocally corresponds, by matrix‐assisted laser‐desorption ionization–time‐of‐flight MS, to the characteristic monoprotonated ion of trypanothione‐(bimane)2withm/z1104.4 and the trypanothione‐(bimane) withm/z914.3. The PCR product consisted of 1476 bp (491 deduced amino acids), has sequences diagnostic for the reducing catalytic site (CVNVGC) as well as domains for binding NADPH, FAD I and FAD II that are present in all members of this group of disulphide‐reducing enzymes, as well as those unique to TRs. The putative protein sequence is 86% identical with that of TR fromT. cruziand it is also clearly distinguishable from other related reductases by phylogenetic analysis. We can conclude, from these highly reliable experiments, thatE. histolyticacontains the TR enzyme and the thiol compound trypanothione that was previously supposed to occur only in trypanosomatids.
The fractal structure of polycation–DNA complexes
Authors: Sarkar Supti , Lee Li Kim , Hart Stephen L. , Hailes Helen C. , Levy Susana M. , Tabor Alethea , Shamlou Parviz Ayazi
Published: March 2005

We used static light scattering to obtain new measurements on the internal structure of aggregated non‐viral gene‐delivery particles in colloidal suspension. The vector particles are prepared by charge neutralization of plasmid DNA either by poly‐l‐lysine or by a Lipofectin/integrin‐targeting peptide. We use established theories of the stability of colloidal particles and fractal concepts to explain the aggregation processes and demonstrate the existence of a new property (fractal dimension) of the aggregated vector particles. Aggregation is shown to produce particles with fractal dimensions in the range between 1.8 and 2.4; the former suggests a loose three‐dimensional structure and the latter characterizes an aggregation process that leads to the formation of particles with tightly packed structures. We show that the fractal dimension of the vector particles is sensitive to changes in physicochemical conditions (ionic strength) of the buffer solution and propose that fractal dimension may provide a useful means of monitoring the physical state of non‐viral delivery‐vector particles during preparation and storage.
Effects of buffer properties on cyclodextrin glucanotransferase reactions and cyclodextrin production from raw sago (Cycas revoluta) starch
Authors: Kamaruddin Kamarulzaman , Illias Rosli Md. , Aziz Suraini Abdul , Said Mamot , Hassan Osman
Published: March 2005

Results from the present study have shown that the ionic species of buffers, pH values and reaction temperature can affect the enzyme unit activities and product specificity of Toruzyme® (Novo Nordisk A/S Bagsvaerd, Denmark) CGTase (cyclodextrin glucanotransferase). Applying a similar reaction environment (acetate buffer, pH 6.0; temperature, 60 °C), the CGTase was found to be capable of producing pre dominantly β‐cyclodextrin from either raw or gelatinized sago (Cycas revoluta) starch. Changing the buffer from acetate to phosphate reduced the yield of β‐cyclodextrin from 2.48 to 1.42 mg/ml and also affected the product specificity, where production of both α‐ and β‐cyclodextrins were more pronounced. The decrease in the production of cyclodextrins in phosphate buffer was significant at both pH 6.0 and 7.0. However, changing the buffer to Tris/HCl (pH 7.0) showed a significant increase in β‐cyclodextrin production. Increasing the ionic strength of sodium acetate and Tris/HCl buffers at pH 6.0 and 7.0 to equivalent ionic strength of phosphate buffers showed no significant effects on cyclodextrin production. Higher yield of cyclodextrins at pH 7.0 when Tris/HCl was used might be due to the binding of chloride ions at the calcium‐binding sites of the CGTase, resulting in the shift of the optimum pH close to physiological environment, leading to an increase in the activities and specificity.
Enzymic asymmetric hydrolysis of d,l‐p‐hydroxyphenylglycine methyl ester in aqueous ionic liquid co‐solvent mixtures
Authors: Lou Wenyong , Zong Minhua , Wu Hong
Published: March 2005

An aqueous solution of ionic liquid BMIM·BF4 (1‐butyl‐3‐methylimidazolium tetrafluoroborate) was used as the reaction medium for the asymmetric hydrolysis of d,l‐p‐hydroxyphenylglycine methyl ester to enantiopure l‐HPG (l‐p‐hydroxyphenylglycine) for the first time. Papain was screened out from five proteases and two lipases tested because of its high activity and enantioselectivity for this reaction. A comparative study demonstrated that papain is more active, enantioselective and stable in the sodium phosphate buffer solution of BMIM·BF4 than in aqueous buffer and in the buffer solutions of several typical organic solvents examined. l‐HPG with an e.e. (enantiomeric excess) of 95.6% and the yield of 47.4% (on a mole basis) could be obtained when the reaction was performed in a buffer solution of 12.5% (v/v) BMIM·BF4 (pH 7.0). The aqueous ionic liquid co‐solvent increased papain's half‐life by 3.1‐, 3.8‐, 4.7‐ and 16.3‐fold when compared with aqueous buffer, aqueous propan‐2‐ol, aqueous acetonitrile and aqueous 1,4‐dioxan co‐solvent respectively at 40 °C. When hydrolysis was conducted under reduced pressure, the yield, the e.e. of the l‐HPG and the e.e. of remaining d‐hydroxyphenylglycine methyl ester achieved were as high as 49.8, 98.1 and >99.0% respectively.
The combined effects of two anti‐aggregatory agents, α‐cyclodextrin and Ca2+, on the refolding process of denatured α‐amylase
Authors: Yazdanparast Razieh , Khodarahmi Reza
Published: March 2005

It is now a well‐known fact that α‐CD (α‐cyclodextrin) and Ca2+ are two important folding agents in the re‐activation and refolding processes of many denatured enzyme solutions. Bacillus sp. α‐amylase was extensively denatured in a 6 M guanidinium chloride solution overnight. Under suitable renaturation conditions, 20–30% more activity was recovered in the presence of various concentrations of α‐CD (0–100 mM). Similarly, 25–30% more activity was recovered under the influence of different concentrations of Ca2+ (0–100 mM). Regardless of these results, both α‐CD and Ca2+ at 100 mM concentrations were separately capable of preventing the extent of aggregate formation by 86 and 77% respectively. These observations clearly indicate that the effects of α‐CD and/or Ca2+ on the process of aggregation and refolding (activity recovery) are not synchronized: both agents mostly act as anti‐aggregatory agents instead of acting as refolding agents.
High‐level expression of a neoagarobiose‐producing β‐agarase gene from Agarivorans sp. JAMB‐A11 in Bacillus subtilis and enzymic properties of the recombinant enzyme
Authors: Ohta Yukari , Hatada Yuji , Ito Susumu , Horikoshi Koki
Published: March 2005

The structural gene for a neoagarobiose‐producing β‐agarase of an Agarivorans isolate was expressed in Bacillus subtilis. High‐level production of the recombinant enzyme was achieved corresponding to a level of 1.9×104 units/l of the culture broth. The efficiency of the production is thus 30‐fold greater than that of the original strain. The recombinant enzyme (RagaA11) had a molecular mass of 105 kDa and a specific activity of 371 units/mg. The optimal pH and temperature of the enzyme were 7.5–8.0 and 40 °C respectively. The enzyme is an endo‐type β‐agarase hydrolysing not only agarose, but also neoagarotetraose, to yield neoagarobiose as the final main product, representing approx. 90 mol% of total products. RagaA11 would be useful for industrial production of neoagarobiose.
Mechanisms of translational regulation in Drosophila
Authors: Wilhelm James E. , Smibert Craig A.
Published: March 2005

Translational regulation plays an essential role in many phases of the Drosophila life cycle. During embryogenesis, specification of the developing body pattern requires co‐ordination of the translation of oskar, gurken and nanos mRNAs with their subcellular localization. In addition, dosage compensation is controlled by Sex‐lethal‐mediated translational regulation while dFMR1 (the Drosophila homologue of the fragile X mental retardation protein) controls translation of various mRNAs which function in the nervous system. Here we describe some of the mechanisms that are utilized to regulate these various processes. Our review highlights the complexity that can be involved with multiple factors employing different mechanisms to control the translation of a single mRNA.
Myocardial regeneration with bone‐marrow‐derived stem cells
Authors: Yoon Young‐Sup , Lee Namho , Scadova Heather
Published: March 2005

Despite significant therapeutic advances, heart failure remains the predominant cause of mortality in the Western world. Ischaemic cardiomyopathy and myocardial infarction are typified by the irreversible loss of cardiac muscle (cardiomyocytes) and vasculature composed of endothelial cells and smooth muscle cells, which are essential for maintaining cardiac integrity and function. The recent identification of adult and embryonic stem cells has triggered attempts to directly repopulate these tissues by stem cell transplantation as a novel therapeutic option. Reports describing provocative and hopeful examples of myocardial regeneration with adult bone‐marrow‐derived stem and progenitor cells have increased the enthusiasm for the use of these cells, yet many questions remain regarding their therapeutic potential and the mechanisms responsible for the observed therapeutic effects. In this review article we discuss the current preclinical and clinical advances in bone‐marrow‐derived stem or progenitor cell therapies for regeneration or repair of the ischaemic myocardium and their multiple related mechanisms involved in myocardial repair and regeneration.