bluuebunny/crossref_metadata_2025_split huggingface dataset:
Co-existence of different host-adapted forms of the Myzus persicae group (Hemiptera: Aphididae) in southern Italy
Authors: Margaritopoulos J.T. , Blackman R.L. , Tsitsipis J.A. , Sannino L. 
Published: April 2003

AbstractMultivariate morphometric analysis (method of canonical variates) was used to compare 38 parthenogenetic lineages and three field collections of aphids of the Myzus persicae (Sulzer) group sampled on peach and tobacco in the Caserta region of southern Italy. Comparisons were also made with the morphology of lineages collected on peach in Lehonia, in central eastern Greece away from tobacco-growing regions, and on tobacco in Naphplion, in southern Greece. The lineages were measured after parthenogenetic rearing for one to three generations on the same host (potato) under constant conditions. As in previous work, the multivariate morphometric approach separated the aphids from peach from those feeding on tobacco. The life cycle category of the lineages was also examined. Almost all the lineages from peach in Caserta were holocyclic, yet the lineages from tobacco in the same region were unable to produce sexual morphs. The results suggest that tobacco-adapted and non-tobacco-adapted forms co-exist in the same region in southern Italy, not only because they colonize different host plants, but also because they have different life cycles. This is in complete contrast to the situation in peach-growing areas of northern Greece, and shows that the ecology and population structure of M. persicae is different in neighbouring counties of the Mediterranean area, even where climatic conditions and cultivated crops are similar.
The lectin jacalin induces phosphorylation of ERK and JNK in CD4+ T cells
Authors: Tamma Seetha M Lakshmi , Kalyanaraman V S , Pahwa Savita , Dominguez Paul , Modesto Ron R 
Published: April 2003

Abstract
The CD4 molecule plays an essential role in mediating the transduction of intracellular signals by functioning as a coreceptor for the complex T cell receptor/CD3 and also acts as the primary receptor for human immunodeficiency virus (HIV). Several authors have shown evidence that jacalin, a plant lectin, binds to CD4 and inhibits in vitro HIV infection. We analyzed jacalin-induced intracellular signaling events in CD4+ T cells and have shown that cell activation resulted in tyrosine phosphorylation of intracellular substrates p56lck, p59fyn, ZAP-70, p95 vav, phospholipase C-γ1, and ras activation, as assessed by conversion of ras guanosine 5′-diphosphate to ras guanosine 5′-triphosphate. We further examined extracellular regulated kinase (ERK) and c-jun NH2-terminal kinase (JNK) phosphorylation following stimulation with jacalin. The data indicate that the kinetics of JNK phosphorylation is delayed. Optimum phosphorylation of ERK2 was observed by 10 min, and that of JNK was observed by 30 min. Pretreatment with gp120 followed by stimulation with jacalin resulted in marked inhibition of all of the aforementioned intracellular events. The data presented here provide insight into the intracellular signaling events associated with the CD4 molecule–jacalin–gp120 interactions and HIV-induced CD4+ T cell anergy. Jacalin may be used as a possible tool for the study of CD4-mediated signal transduction and HIV-impaired CD4+ T cell activation.
Partially Hydrogenated 1,1′‐Binaphthyl as Ligand Scaffold in Metal‐Catalyzed Asymmetric Synthesis
Authors: Au‐Yeung Terry T.‐L. , Chan Shu‐Sun , Chan Albert S. C. 
Published: April 2003

AbstractAlthough chiral binaphthyl‐type ligands are already known to be effective over a broad spectrum of reactions, they sometimes fail in providing high enantioselectivities in some catalytic asymmetric reactions. This article summarizes recent attempts to elevate their performance by partly hydrogenating the naphthyl components of the binaphthyl. The synthetic routes to some of these ligands are briefly outlined. Positive results are observed in asymmetric hydrogenation, alkylation, borane reduction, epoxidation and hetero‐Diels–Alder reactions. The function of the partially reduced binaphthyl skeleton, however, can sometimes be disadvantageous or ambiguous as illustrated in reactions such as asymmetric ring‐closing metathesis, 1,4‐conjugate addition, epoxidation, allylic alkylation, trimethylsilylcyanation, epoxide ring‐opening and hydroformylation.
Polymer‐Supported Bisacetoxybromate(I) Anion –‐An Efficient Co‐Oxidant in the TEMPO‐Mediated Oxidation of Primary and Secondary Alcohols
Authors: Brünjes Marco , Sourkouni‐Argirusi Georgia , Kirschning Andreas 
Published: April 2003

AbstractA polymer‐bound reagent for the efficient oxidation of primary alcohols to aldehydes and secondary alcohols to ketones in the presence of a catalytic amount of 2,2,6,6‐tetramethyl‐1‐piperidinyloxyl (TEMPO) is described. The oxidation process is particular mild and allows one to prepare aldehydes with α‐chirality without racemization. This also includes the synthesis of α‐aminoaldehydes. In most cases, work‐up of this heavy metal‐free oxidation is achieved by simple filtration followed by removal of the solvent. Insight into the role of the bromate(I) anion in the oxidation process was gained from the TEMPO‐mediated oxidation of benzaldehyde in the presence of the hypochlorite anion loaded on an anion exchange resin.
Randomized comparison of the coil‐design Crossflex and the tubular NIR stent
Authors: Thuesen Leif , Andersen Henning R. , Krusell Lars R. , Bøtker Hans E. , Jørgensen Erik , Kelbæk Henning , Kristensen Steen D. 
Published: April 2003

AbstractThe purpose of this study was to compare the angiographic outcome of implantation of the coil‐design Crossflex stent with the tubular NIR stent for treatment of coronary artery stenoses. Two hundred twenty‐three patients with one genuine coronary artery lesion were randomized to implantation with a 15 mm Crossflex stent (n = 112) or a 16 mm NIR stent (n = 111). The patients had angiographic follow‐up after 6 months. Primary endpoint was minimal luminal diameter (MLD) after 6 months. There was a similar clinical outcome in the two groups. At 6‐month follow‐up, the MLD was significantly lower in the Crossflex group (1.94 ± 0.79 mm) than in the NIR group (2.37 ± 0.84 mm; P < 0.001). Early gain was the same in the two groups. Late loss and percent diameter stenoses were significantly higher in the Crossflex group. The binary restenoses rate was 26% and 17% in the Crossflex and the NIR groups, respectively (P = NS). The coil‐design Crossflex stent was found to be inferior to the tubular NIR stent concerning late loss and MLD at 6‐month follow‐up. Cathet Cardiovasc Intervent 2003;59:8–12. © 2003 Wiley‐Liss, Inc.
Endovascular closure of a large renal arteriovenous fistula
Authors: Rimon Uri , Garniek Alexander , Golan Gil , Schneiderman Jacob , Morag Benyamina 
Published: April 2003

AbstractA case is described of a large renal arteriovenous fistula causing long‐term cardiovascular complications. Successful percutaneous embolization was achieved using temporary occlusion balloons, Guglielmi detachable coils, regular nondetachable spring coils, and cyanacrylate. The advanced therapeutic tools we used can improve the prognosis of patients with large and complicated arteriovenuos fistulas and prevent surgery. Cathet Cardiovasc Intervent 2003;59:66–70. © 2003 Wiley‐Liss, Inc.
Regio‐ and Stereoselective Double Addition of Anionic C‐Nucleophiles to Cobalt‐Stabilized Acetylenedicarbaldehyde
Authors: Sui‐Seng Christine , Soleilhavoup Michèle , Maurette Luc , Tedeschi Christine , Donnadieu Bruno , Chauvin Remi 
Published: April 2003

AbstractThough intrinsically unstable, Gorgues’ acetylenedicarbaldehyde is an appealing, highly functional C4 synthon, which can be stabilized by η2 complexation to a Co2(CO)6 unit. In contrast to the homologous dibenzoylacetylene complex, it can be used as a normal, doubly electrophilic, non‐conjugated γ‐dicarbonyl substrate toward alkyl‐, aryl‐, and alkynyllithium compounds or magnesium bromides; these anionic C‐nucleophiles do not predominantly attack at the metal‐carbonyl center. The 1,4‐dialkyl‐ and 1,4‐diphenylbut‐2‐yne‐1,4‐diol products are obtained with significant meso/dl diastereoselectivity (4−66% de), which can be explained by a simple model based on X‐ray diffraction data and MM calculations. The alkyl‐ and arylmagnesium bromide reactants are more selective than their lithium counterparts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Regioselective Spiroannulations of α‐Acetyl Lactones
Authors: Christoffers Jens , Oertling Heiko , Frey Wolfgang 
Published: April 2003

AbstractMonocyclic spiroannulation precursors 3a−c were obtained by Michael reactions of α‐acetyl lactones 6a−c with methyl vinyl ketone (7). The selective formation of either regioisomer of both β‐oxo (5a−c) and δ‐oxo (4a−c) lactones from 3a−c was achieved by varying the reaction conditions. The δ‐oxo lactones 4a−c were obtained under basic (buffered) conditions in a pyrrolidine/AcOH system. Under acidic conditions, the annulation reaction afforded β‐oxo lactones 5a−c. Byproducts 8b,c were identified to be the decomposition products of β‐oxo lactones 5b and 5c by comparison with the spectra of the alcohols 10b,c derived directly from δ‐oxo lactones 4b and 4c by saponification/decarboxylation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The diagnostic utility of FLAIR imaging in clinically verified amyotrophic lateral sclerosis
Authors: Zhang Lijuan , Uluǧ Aziz M. , Zimmerman Robert D. , Lin Michael T. , Rubin Michael , Beal M. Flint 
Published: April 2003

AbstractPurposeTo explore the overall diagnostic ability of magnetic resonance (MR) fluid‐attenuated inversion recovery (FLAIR) imaging for clinically verified amyotrophic lateral sclerosis (ALS).Materials and MethodsAbnormal signal intensity in FLAIR images of 18 patients with ALS and 18 age‐matched normal controls were scored and compared. Six patients had serial MR imaging scans within 97 days. Mann Whitney U statistics and ANOVA were used for statistical analysis.ResultsHyperintensity in the subcortical white matter (SWM) and the dark line along the posterior rim of the precentral gyri were found more frequently in patients with ALS. The scores for these two signs were significantly different from those of normal controls. Hyperintensity in the corticospinal tract (CST) was found in both ALS and normal controls, but the difference was not statistically significant. ANOVA on the serial FLAIR studies revealed no significant difference in the scores among the series. The hyperintensity in SWM had a sensitivity of 56% and specificity of 94%, while the dark line in the motor cortex had a 74% sensitivity and 67% specificity.ConclusionHyperintensity in SWM and the dark line along the posterior rim of the precentral gyri appeared more frequently in the patients with ALS. SWM hyperintensity has a better specificity in association with clinically verified ALS, while the motor dark line has a better sensitivity. No correlation was found between the FLAIR findings and progression of the disease. J. Magn. Reson. Imaging 2003;17:521–527. © 2003 Wiley‐Liss, Inc.
The use of reflectometric test kits for estimating nitrification and soil invertase activity in the field
Authors: Gromes Reiner , Behrens Sandra , Nagel Elke 
Published: April 2003

AbstractThe objective of this study was to test the applicability of different reflectometric test kits for the determination of potential nitrification and the activity of invertase in soil directly in the field. For the investigation of nitrification in the field, the incubation time was reduced because a linear correlation between incubation time and nitrification rates was found. Likewise, a linear correlation between invertase activity and the incubation temperature was observed which allowed for the calculation of temperature‐dependent factors. Activity measurements in the field at lower temperatures in comparison to the standard procedure were corrected by these factors. Ten different soils were investigated for potential nitrification and invertase activity with standard methods in comparison to field tests with reflectometric detection of the reaction products. The results showed that the reflectometric test kits are suitable for the estimation of potential nitrification and invertase activity directly in the field.
Comparative Crystallization Study of Several Linear Dinitramines in Nitrocellulose‐Based Gels
Authors: Spitzer Denis , Braun Silke , Schäfer Michael Richard , Ciszek Fabrice 
Published: April 2003

AbstractThis study deals with the crystallization behaviour of several dinitramines with plasticizing abilities in a nitrocellulose‐based gel. The tendency of these compounds to interact with nitrocellulose is an important parameter for the development of new propellants, especially for those which should have a temperature‐independent combustion. It is shown that, on the basis of their crystallization behaviour, the nine studied dinitramines form three different groups. Whereas the first one (large symmetrical molecules) exhibits a strong crystallization tendency, the second group (asymmetric compounds) has low crystalline contents and shows a good interaction capacity with nitrocellulose. At last, DNDA6 (2,4‐dinitro‐2,4‐diazahexane) with 3.3 noncrystallizing molecules per anhydroglucosidic unit of nitrocellulose, presents the most pronounced interaction with nitrocellulose, due to its lowest content of crystalline plasticizer.
Classical Langevin dynamics for model Hamiltonians
Authors: Cohen Morrel H. 
Published: April 2003

AbstractWe propose a scheme for extending the model Hamiltonian method developed originally for studying the equilibrium properties of complex perovskite systems to include Langevin dynamics. The extension is based on Zwanzig's treatment of nonlinear generalized Langevin's equations. The parameters entering the equations of motion are to be determined by mapping from first‐principles calculations, as in the original model Hamiltonian method. The scheme makes possible, in principle, the study of the dynamics and kinetics of structural transformations inaccessible to the original model Hamiltonian method. Moreover, we show that the equilibrium properties are governed by an effective Hamiltonian which differs from that used in previous work by a term which captures the coherent part of the previously ignored dynamical interaction with the omitted degrees of freedom. We describe how the additional information required for the Langevin equations can be obtained by a minor extension of the previous mapping.
Calculation of Feynman diagrams in space and time by stationary phase
Authors: Gutzwiller M. 
Published: April 2003

AbstractFeynman diagrams are usually derived in relativistic space and time, and then immediately converted into energy and momentum by a Fourier transform. A method is proposed that allows keeping the external vertices at fixed locations and finite times, while the internal vertices are integrated in space‐time as well. Propagators between the vertices are the well‐known Bessel functions of the relativistic distance. The example of the Compton effect is worked out.
Lattice effects in manganites
Authors: Iadonisi G. , Cataudella V. , De Filippis G. , Marigliano Ramaglia V. , Perroni C. A. , Ventriglia F. 
Published: April 2003

AbstractThe interplay of the electron–phonon interaction and of the double and super‐exchange magnetic effects in the La1–xCaxMnO3 perovskites with 0 < x < 0.5 is studied. It is shown that treating the electron–phonon interaction in a fully quantum manner in the intermediate electron–phonon coupling regime a charge density instability occurs near the metal–insulator transition, induced by either temperature or hole doping. Also the effects of the magnetic field and the oxygen isotope substitution on the phase diagram, the electron–phonon correlation function and the infrared absorption at x = 0.3 is studied. The lattice displacements show a strong correlation with the conductivity and the magnetic properties of the system. Finally the conductivity spectra are characterized by a marked sensitivity to the external parameters near the phase boundary.
Interplay between inelastic X‐ray scattering and ab initio density‐response calculations: Insight into the electronic correlations in aluminum
Authors: Tischler J. Z. , Larson B. C. , Zschack P. , Fleszar A. , Eguiluz A. G. 
Published: April 2003

AbstractInelastic X‐ray scattering (IXS) measurements on Al have been analyzed in conjunction with ab initio, time‐dependent density functional theory (TDDFT) calculations of the electron–hole excitation spectrum. The dynamical structure factor evaluated with use of the many‐body kernel fxc obtained within the adiabatic extension of the local‐density approximation (ALDA) is shown to be in good agreement with the IXS energy‐loss data for energies up to about 20 eV, for momentum transfers up to twice the Fermi wave vector. For larger energy transfers the complex, frequency‐dependent fxc obtained by Devreese and collaborators via dynamical‐exchange decoupling techniques is shown to lead to a description of the IXS data comparable with that of the ALDA. For low energies the ALDA works better, a conclusion with a simple physical interpretation. The analysis of the relative merits of the models for the many‐body interactions is made using IXS cross sections that were obtained in absolute units; to this end, a procedure was introduced which is applicable for arbitrary materials, not just for sp‐bonded Al.
Many‐body vacuum diagrams and their recursive graphical construction
Authors: Pelster A. , Glaum K. 
Published: April 2003

AbstractThe grand‐canonical potential of many‐body physics can be considered as a functional of the interaction‐free correlation function. As such it obeys a nonlinear functional differential equation which can be turned into a recursion relation. This is solved graphically order by order in the two‐particle interaction to find all connected vacuum diagrams with their proper weights. As a special case, the procedure is applied to generate the Hugenholtz diagrams for a weakly interacting Bose gas.
New approach to study melting processes in metal nanoparticles: capacitance measurements
Authors: Parravicini G. B. , Stella A. , Ungureanu M. C. , Merli P. G. , Migliori A. , Kofman R. 
Published: April 2003

AbstractThe size reduction of the nanosystems with respect to macroscopic samples (or also in the micrometric size range) necessarily implies a concomitant and substantial increase of the surface to volume ratio. The surface atoms often play a role in determining or affecting basic properties of the samples investigated. As a consequence, the quest for new techniques specialized to the study of the electrical, optical or thermodynamic behavior of the surfaces or interfaces is becoming progressively more important. By means of capacitance measurements on metallic (specifically Ga) nanoparticles, through the relationship between derivative of the dielectric constant with respect to the temperature and the contribution to entropy due to the applied electric field, we show that initial disorder starts to take place ≈65 K before full melting. The premelting region is characterized by two regimes, which will be briefly illustrated.
Festschrift in honour of Jozef T. Devreese
Authors: Brosens Fons , Fomin Vladimir , Lemmens Lucien , Peeters François 
Published: April 2003

AbstractThe present special issue of physica status solidi (b) is dedicated to Professor Dr. Jozef T. Devreese on the occasion of his 65th birthday. Professor Devreese from the Laboratory of Theoretical Physics of Solids at Antwerp University is a distinguished theoretical physicist with outstanding achievements in various areas of condensed matter physics over many decades. 40 contributions written by his colleagues, collaborators, and friends were assembled in this edition.The cover picture of this Liber Amicorum shows an artist's view of the polaron, originally sketched by Jozef T. Devreese for the cover of Ref. [1].
Predicting Passive Intestinal Absorption Using A Single Parameter
Authors: Sanghvi Tapan , Ni Nina , Mayersohn Michael , Yalkowsky Samuel H. 
Published: April 2003

AbstractA model is proposed for the prediction of either high or low fraction absorbed for an orally administered, passively transported drug on the basis of a new absorption parameter, Π. The model includes only two inputs: the octanol‐water partition coefficient (Kow) and the dimensionless oversaturation number (OLumen). The latter is the ratio of the concentration of drug delivered to the gastrointestinal (GI) fluid to the solubility of the drug in that environment. Thus, OLumen is equal to the dose‐normalized solubility for suspensions and unity for solutions. The value of Π increases with an increase in Kow and a decrease in OLumen for suspensions, and is equal to Kow for solutions.
A model and a general problem on plastic flow under large deformations
Authors: Litvinov W.G. 
Published: April 2003

AbstractWe introduce a constitutive equation of the plastic flow such that a medium is considered as a fluid, whose viscosity depends on the second invariant of the tensor of strains accumulated under a plastic flow and on the second invariant of the deviator of the stress tensor. For this constitutive equation a general problem on plastic flow under large deformations is formulated and studied. It is supposed that the surface forces acting on a body are defined in the form of a feedback such that the forces at a moment t depend on the shape of the body at this moment. The problem consists of finding the configuration of the deformed body at each moment of time, velocities, strains, and stresses. The general problem is approximated by problems with delay. We prove the existence and the uniqueness of a solution for the problems with delay. The solution of the original problem is obtained as a limit of the solutions of the problems with delay as the delay parameter tends to zero.
Wave propagation in a waveguide
Authors: Rawlins A.D. , Mahmood‐ul‐Hassan  
Published: April 2003

AbstractWe shall consider the sound radiation of a surface wave mode which propagates towards the mouth of a semi‐infinite waveguide which supports surface waves. This semi‐infinite waveguide is symmetrically located inside an infinite waveguide whose surface is lined with an absorbent surface. The whole system constitutes a new trifurcated waveguide boundary value problem. This model results in a scalar Wiener‐Hopf problem. An exact closed form solution is obtained with the aid of the Wiener‐Hopf technique. The theoretical problem solved has application in acoustics and electromagnetism.
A singular Homann differential equation
Authors: Agarwal R.P. , O'Regan D. 
Published: April 2003

AbstractGeneral existence criteria are presented for the boundary value problem y″ + qf(t, y, y′) = 0, 0 < t < 1, with ‐ay(0) + by′ (0) = c0 and y(1) = 0. Our nonlinearity f may be singular at y = 0.