bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of drug release from thermo‐ and pH‐sensitive poly(N‐isopropylacrylamide/itaconic acid) copolymeric hydrogels
Authors: Taşdelen B. , Kayaman‐Apohan N. , Güven O. , Baysal B. M.
Published: August 2004

N‐Isopropylacrylamide/itaconic acid copolymeric hydrogels were prepared by irradiation of the ternary mixtures of N‐isopropylacrylamide/itaconic acid/water by γ‐rays at ambient temperature. The dependence of swelling properties and phase transitions on the comonomer concentration and temperature were investigated. The hydrogels showed both temperature and pH responses. The effect of comonomer concentration on the uptake and release behavior of the hydrogels was studied. Methylene blue (MB) was used as a model drug for the investigation of drug uptake and release behavior of the hydrogels. The release studies showed that the basic parameters affecting the drug release behavior of the hydrogels were pH and temperature of the solution. Copyright © 2004 John Wiley & Sons, Ltd.
Role played by the head size of some non‐ionic surfactants on their adsorption onto montmorillonite clay
Authors: Shalaby Magda N.
Published: August 2004

Sorption behavior of polyoxethylene(n)monooleate series [Ol(EO)n] onto montmorillonite clay was studied at 25°C to investigate the influence of the surfactant's head size on the sorption process. All the tested surfactants exhibited L‐shaped isotherms that means a strong interaction between the adsorbent and the adsorbate. Also, all the obtained isotherms ended with a drastic increase in the isotherm slope at nearly constant equilibrium concentration. This abrupt increase reflected the fairly high affinity of the tested surfactants to the clay surface at high bulk concentration region. The maximum amount adsorbed at the plateau region, Γmax, was calculated according to the Langmuir adsorption theory and followed the order: Ol(EO)14 > Ol(EO)20 < Ol(EO)40 < Ol(EO)80. In case of short ethylene oxide (EO) chain, Γmax decreased with the increase in the chain length; but a reverse result was obtained in case of surfactants with longer EO chain length (20 to 80 units). The free energy of adsorption, ΔG°ad, had negative values indicating the spontaneous adsorption of surfactant molecules onto clay. The values of ΔG°ad increased with increasing EO units from 14 to 20 units and decreased with further elongation in the EO chain from 20 to 80 units. Copyright © 2004 John Wiley & Sons, Ltd.
Quantum chemical calculation of structures and NMR chemical shifts of substituted buta‐1,3‐dienyl‐2‐cations
Authors: Siehl Hans‐Ullrich , Brixner Sandra
Published: August 2004

A computational study of 13C NMR chemical shifts of a series of α‐vinyl substituted vinyl cations (1,3‐dienyl‐2‐cations) 1–6 is presented. The sensitivity of the predicted isotropic shifts to electron correlation, basis set and geometry effects is explored. Comparison with experimental 13C NMR chemical shifts shows that second‐order Møller–Plesset perturbation theory calculations [GIAO‐MP2/tzp//MP2/6–31G(d,p)] perform adequately (deviation ≈ 3–4 ppm) for all carbons of cations 1–6, except for carbons in 6 involved in cyclopropyl hyperconjugation, which give some larger deviations (≈ 6–9 ppm). The Hartree–Fock self‐consistent field (GIAO‐HF/tzp) approximation as well as GIAO‐DFT‐methods together with hybrid functionals (B3LYP) give unsatisfactory results and cannot be relied upon to predict the sequence of signals in the 13C NMR spectra of these type of carbocations. Copyright © 2004 John Wiley & Sons, Ltd.
The impact of the herbicide glyphosate on leaf litter invertebrates within Bitou bush, Chrysanthemoides monilifera ssp rotundata, infestations
Authors: Lindsay Elizabeth A , French Kris
Published: August 2004

Chrysanthemoides monilifera ssp rotundata (L) T Norl (Bitou bush) is a serious environmental weed along the southeast coast of Australia. The herbicide glyphosate is commonly used to control C monilifera on the New South Wales coastline, but there have been few studies examining the effects of this herbicide on invertebrate communities in the field, especially on sand dunes. Control and impact sites were selected in coastal hind dunes heavily infested with C monilifera, and the impact sites were sprayed with a 1:100 v/v dilution of glyphosate‐isopropyl 360 g AE litre−1 SL (Roundup Biactive). Leaf litter invertebrates were sampled before spraying and after spraying by collecting fixed areas of leaf litter in both the control and impact sites. Samples were sorted for particular invertebrates involved in leaf litter decomposition and some of their predators. This study did not identify any significant direct or indirect effects on leaf litter invertebrate abundance or community composition in the four months following herbicide application. The litter invertebrate assemblages were highly variable on a small spatial scale, with abiotic factors more strongly regulating leaf litter invertebrate numbers than glyphosate application. These results conflict with previous studies, indicating that the detrimental indirect effects herbicide application has on non‐target litter invertebrates may depend upon the application rate, the vegetation community and structure and post‐spray weather. Copyright © 2004 Society of Chemical Industry
Electronic transition moment with spin‐orbit coupling of the molecular ion KRb+
Authors: Korek M. , Younes G.
Published: August 2004

By using the electronic wave functions obtained from an ab initio calculation, including the spin‐orbit coupling, the electronic transition moments have been investigated for two bound states of symmetry Ω = 1/2 and Ω = 3/2 of the molecular ion KRb+. Based on a canonical functions approach for the determination of the vibrational wave functions, the matrix elements have been calculated for the bound states considered for v = 0, 10, 20 with v′‐ v = 0, 1, 2, …, 6; by using the same canonical approach, the eigenvalues and abscissas of the corresponding turning points (rmin and rmax) have been investigated for these states that obtained from a theoretical ab initio calculation up to v = 105. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Continuum eigen‐functions of 1‐D time‐independent Schrödinger equation solved by symplectic algorithm
Authors: Qi Yue‐Ying , Liu Xue‐Shen , Ding Pei‐Zhu
Published: August 2004

We present the symplectic algorithm for solving the continuum eigen‐functions of 1‐dimensional (1D) time‐independent Schrödinger equation, which keeps Wronskian conservation of linearly independent continuum eigen‐functions. This symplectic algorithm has been applied to the computation of the linearly independent continuum eigen‐functions of both 1D soft‐coulomb potential and Pöshl–Teller short‐range potential as well as the radial continuum eigen‐functions of hydrogen atom. The numerical results using the symplectic algorithm are in agreement with the existing theories. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Quantum electronic transport in a configuration interaction basis
Authors: Delaney P. , Greer J. C.
Published: August 2004

An overview of a many‐body approach to calculation of electronic transport in molecular systems is given. The physics required to describe electronic transport through a molecule at the many‐body level, without relying on commonly made assumptions such as the Landauer formalism or linear response theory, is discussed. Physically, our method relies on the incorporation of scattering boundary conditions into a many‐body wavefunction and application of the maximum entropy principle to the transport region. Mathematically, this simple physical model translates into a constrained nonlinear optimization problem. A strategy for solving the constrained optimization problem is given. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Single nucleotide polymorphism analysis in the human phosphatase PTPrj gene using matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry
Authors: Powell Ned , Dudley Ed , Morishita Mariko , Bogdanova Tetyana , Tronko Mykola , Thomas Gerry
Published: August 2004

Data derived from analysis of single nucleotide polymorphisms (SNPs) are being applied in many diverse fields, from medical studies of disease mechanisms and individual drug response, to population genetics for tracking migration and mixing of ancestral groups and also in forensic science for the identification of human remains and identification of individuals from bodily samples. All these applications have in common the need to generate data for multiple loci from large numbers of samples. Matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS) is a promising platform for the generation of such data and we present a simple, flexible and robust technique for SNP determination. We demonstrate these features by typing two SNPs (Q276P and R326Q) in the human phosphatase gene PTPrj, which has been implicated in the aetiology of colon, lung, breast and thyroid cancers. A nucleotide depletion primer extension assay using no commercial kits or dideoxyNTPs was used to genotype a panel of DNAs derived from thyroid cancer patients and normal volunteers. The results obtained were in perfect agreement with those generated via restriction fragment length polymorphism analysis. No significant association was noted between possession of either allelic variant and a disease state, but the technique was validated as simple, flexible and appropriate for application in this context. Furthermore, it was highly cost‐effective and required minimal optimisation, rendering it ideal for this type of pilot study. Copyright © 2004 John Wiley & Sons, Ltd.
Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction
Authors: Unger Matthias , Frank Andreas
Published: August 2004

Here we describe a liquid chromatography/mass spectrometry (LC/MS) method with automated online extraction (LC/LC/MS) to simultaneously determine the in vitro inhibitory potency of herbal extracts on six major human drug‐metabolising cytochrome P450 enzymes. Substrates were incubated with a commercially available mixture of CYP1A2/2C8/2C9/2C19/2D6 and 3A4 from baculovirus‐infected insect cells and the resulting metabolites were quantified with LC/LC/MS using electrospray ionisation in the selected ion monitoring mode. Consistent inhibitory activities were obtained for known inhibitors and plant extracts using the enzyme/substrate cocktail and the individual enzymes/substrates. Popular herbal remedies including devil's claw root (Harpagophytum procumbens), feverfew herb (Tanacetum parthenium), fo‐ti root (Polygonum multiflorum), kava‐kava root (Piper methysticum), peppermint oil (Mentha piperita), eucalyptus oil (Eucalyptus globulus), red clover blossom (Trifolium pratense) and grapefruit juice (GJ; Citrus paradisi) could be identified as inhibitors of the applied CYP enzymes with IC50 values between 20 and 1000 μg/mL. Copyright © 2004 John Wiley & Sons, Ltd.
Identification of some new clemastine metabolites in dog, horse, and human urine with liquid chromatography/tandem mass spectrometry
Authors: Tevell Annica , Bondesson Ulf , Törneke Karolina , Hedeland Mikael
Published: August 2004

The metabolism of clemastine was studied in dogs, horses, and humans after a single dose of Tavegyl®. The urine collected was extracted by solid‐phase extraction or hydrolyzed with β‐glucuronidase and then extracted by liquid‐liquid extraction, prior to analysis for unchanged drug and phase I and II metabolites by liquid chromatography/tandem mass spectrometry. The metabolites were identified by their molecular mass and interpretation of the product ion spectra, since no standard substances were available. Unchanged drug was recovered in urine samples from dogs and humans, but not from horses. In dogs and humans, the phase I metabolite, norclemastine, was identified, and clemastine metabolites with one and two additional oxygens were found in all three species. In horses and dogs monohydroxylation on one of the aromatic rings or the adjacent methyl group was favored while, in humans, the additional oxygen was positioned on either the aromatic or the aliphatic part of the structure, and the aliphatic reaction seemed to result in at least three isomers. In the metabolites with two additional oxygens, both the oxygens were found on the aliphatic fragment in humans and dogs, whereas they were situated on the aromatic part of the structure in horses. In human patients, glucuronidated monohydroxyclemastine was recovered, and in urine from horses both mono‐ and dihydroxyclemastine glucuronides were identified, while phase II metabolites could not be recovered from the dog urine. Clemastine metabolism in dogs and horses has, to our knowledge, not been studied before, and new metabolites from humans are presented in this article. Thus, the metabolites described in the present work have not been previously reported in the literature. Copyright © 2004 John Wiley & Sons, Ltd.
Anticipation‐based partial redundancy elimination for static single assignment form
Authors: VanDrunen Thomas , Hosking Antony L.
Published: August 2004

Partial redundancy elimination (PRE) is a program transformation that identifies and eliminates expressions that are redundant on at least one (but not necessarily all) execution paths of a program without increasing any path length. Chow, Kennedy and co‐workers devised an algorithm (SSAPRE) for performing partial redundancy elimination on intermediate representations in static single assignment (SSA) form. The practicality of that algorithm is limited by the following concerns: (1) it makes assumptions about the namespace that are stronger than those of SSA form and that may not be valid if other optimizations have already been performed on the program; (2) if redundancies occur in nested expressions, the algorithm may expose but not eliminate them (requiring a second pass of the algorithm); (3) it misses cases covered by the state of the art in PRE; and (4) it is difficult to understand and implement. We present an algorithm (A‐SSAPRE) structurally similar to SSAPRE that uses anticipation rather than availability; this algorithm is simpler than SSAPRE, covers more cases, eliminates nested redundancies on a single pass, and makes no assumptions about the namespace. Copyright © 2004 John Wiley & Sons, Ltd.
Comparative chemistry of isolable divalent compounds of silicon, germanium, and tin
Authors: Kira Mitsuo , Ishida Shintaro , Iwamoto Takeaki
Published: August 2004

Recent studies of the synthesis, structures, spectroscopic properties, and reactions of a series of isolable metallylenes (R2E:, E = Si (1), Ge (2), and Sn (3); R2 = 1,1,4,4‐tetrakis(trimethylsilyl)butane‐1,4‐diyl) are summarized. Because these group‐14 metallylenes bear the same helmet‐like ligand, a straightforward discussion of the element‐dependence of the intrinsic properties of the group‐14 element divalent compounds is possible. All these metallylenes were monomeric both in solution and in the solid state, indicating the effective steric protection by the ligand against dimerization. A small σπ conjugation between CSi(substituent) σ orbitals and the vacant npz orbitals of divalent atoms in R2E: exists and the extent decreases in the order E = Si > Ge > Sn, as evidenced by UV‐vis and NMR spectroscopies and X‐ray crystallography. However, the extent of the σπ conjugation in metallylenes 1–3 was much smaller than the electron‐donating effects of neighboring nitrogen atoms in known stable cyclic diamino‐substituted metallylenes, and hence metallylenes 1–3 are regarded as the least electronically perturbed. Comparative studies of the unique reactions among these metallylenes are also discussed. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 4: 243–253; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20019
Structural Study of Alkaline 1‐Phenyl‐1H‐1, 2, 3, 4‐tetrazole‐5‐thiolate Salts: An Example of Periodicity in Alkaline Cations
Authors: Hernández‐Arganis Michelle , Toscano Rubén A. , Moya‐Cabrera Mónica , García‐Montalvo Verónica , Cea‐Olivares Raymundo
Published: August 2004

The alkaline 1‐phenyl‐1H‐1, 2, 3, 4‐tetrazole‐5‐thiolate salts, M[C6H5N4CS] (M = Li (1), Na (2), K (3), Rb (4) and Cs (5)) were obtained and characterized by means of mass spectrometry (FAB+) and NMR (1H; 13C) spectroscopy. The structures of Na (2), K (3), Rb (4) and Cs (5) compounds were determined by X‐ray diffraction methods. The ligand shows a rich variety of coordination patterns with the alkaline cations. The formation of a four‐membered ring MSCN in the compounds with heavier alkali cations (K, Rb and Cs) is shown. In all the cations the coordination number around it increases with the ionic radius. Compounds with Cs+ and Rb+ exhibited the formation of Cs‐C and Rb‐C interactions with the phenyl group.
Synthesis, Crystal Structure, IR Spectra and Thermal Analysis of Na[Ag(sac)2] (sac = saccharinate)
Authors: Yilmaz Veysel T. , Hamamci Sevim , Thöne Carsten
Published: August 2004

The reaction of silver nitrate with sodium saccharinate (Na[sac]) in the presence of 2‐pyridinepropanol in aqueous solution yields the title complex, Na[Ag(sac)2]. The compound crystallizes in the triclinic space group $P {\bar 1}$ [a = 8.0481(6), b = 9.0587(6), c = 11.1642(8) Å; α = 100.064(3), β = 99.917(3) and γ = 92.367(3)°, Z = 2]. The structure consists of Na+ and [Ag(sac)2]‐ ions, in which each silver(I) ion is doubly bridged by the sac ligands, exhibiting a distorted 'T' shaped AgN2O coordination arrangement with one long [Ag‐Osulfonyl = 2.6390(10) Å] and two shorter bonds [Ag‐N = 2.1405(11) and 2.1570(11) Å]. The coordination around silver(I) is trigonal planar and the N‐Ag‐N bond angle is 158.99(5)°. The Na+ ion is five‐coordinate with two carbonyl and three sulfonyl O atoms of the adjacent sac ligands and acts as a bridge between [Ag(sac)2]‐ units, resulting in a three‐dimensional network. The i.r. spectra and thermal decomposition behaviour of Na[Ag(sac)2] are discussed in detail.
Zur Reaktion der Meldrumsäure mit Schwefeldichlorid ‐ Synthese und Eigenschaften eines ungewöhnlichen 1,3‐Dithietans [1]
Authors: Kuhn Norbert , Al‐Sheikh Ahmed , Maichle‐Mößmer Cäcilia , Steimann Manfred , Ströbele Markus
Published: August 2004

Das 1,3‐Dithietan {MelS}2 (8) wird durch Umsetzung der Meldrumsäure MelH2 (1, Mel = C6H6O4) und Schwefeldichlorid in guter Ausbeute erhalten. 8 reagiert mit den Nukleophilen PPh3 und 2,3‐Dihydro‐1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐yliden (12, Im)zu den zwitterionischen Verbindungen Mel‐S‐PPh3 (11) und Mel‐S‐Im (13).Mit wäss. Ammoniak wird das dianionische Disulfid (NH4)2[Mel‐S‐S‐Mel] (14) erhalten. Die Kristalllstrukturen von 8, 11, und 14 werden diskutiert.
On the Landau approximation in plasma physics
Authors: Alexandre R , Villani C
Published: August 2004

This paper studies the approximation of the Boltzmann equation by the Landau equation in a regime when grazing collisions prevail. While all previous results in the subject were limited to the spatially homogeneous case, here we manage to cover the general, space-dependent situation, assuming only basic physical estimates of finite mass, energy, entropy and entropy production. The proofs are based on the recent results and methods introduced previously in [R. Alexandre, C. Villani, Comm. Pure Appl. Math. 55 (1) (2002) 30–70] by both authors, and the entropy production smoothing effects established in [R. Alexandre et al., Arch. Rational Mech. Anal. 152 (4) (2000) 327–355]. We are able to treat realistic singularities of Coulomb type, and approximations of the Debye cut. However, our method only works for finite-time intervals, while the Landau equation is supposed to describe long-time corrections to the Vlasov–Poisson equation. If the mean-field interaction is neglected, then our results apply to physically relevant situations after a time rescaling.

Nous étudions l’approximation de l’équation de Boltzmann par l’équation de Landau quand les collisions rasantes sont dominantes. Alors que tous les résultats connus auparavant en la matière concernaient le cas spatialement homogène, ici nous parvenons à couvrir le cas général, spatialement inhomogène, supposant seulement des estimations a priori physiquement réalistes portant sur la masse, l’énergie, l’entropie et la production d’entropie. Les preuves reposent sur les résultats et méthodes mis au point récemment par les auteurs dans [R. Alexandre, C. Villani, Comm. Pure Appl. Math. 55 (1) (2002) 30–70], et sur les effets de régularisation par production d’entropie établis dans [R. Alexandre et al., Arch. Rational Mech. Anal. 152 (4) (2000) 327–355]. Nos résultats couvrent certaines singularités physiquement réalistes de type coulombien, et des approximations de la coupure de Debye. Cependant, nos résultats s’appliquent sur un intervalle de temps fini, alors que l’équation de Landau est censée décrire les corrections en temps grand de l’équation de Vlasov–Poisson. Si le terme d’interaction de champ moyen est négligé, nos résultats s’appliquent à des situations physiquement réalistes après un changement d’échelle de temps.
A-quasiconvexity: weak-star convergence and the gap
Authors: Fonseca Irene , Leoni Giovanni , Müller Stefan
Published: August 2004

Lower semicontinuity results with respect to weak-

\ast

convergence in the sense of measures and with respect to weak convergence in 

L^p

are obtained for functionals

\upsilon \in L^{1}\left(\Omega ;ℝ^{m}\right)\mapsto \int \limits_{\Omega }f\left(x,\upsilon \left(x\right)\right)\text{dx},

where admissible sequences

\{v_n\}

satisfy a first order system of PDEs

\mathcal Av_n=0

. We suppose that

\mathcal A

has constant rank,

f

is

\mathcal A

-quasiconvex and satisfies the non standard growth conditions

\frac{1}{C}\left(\left|\upsilon \right|^{p} - 1\right)⩽f\left(\upsilon \right)⩽C\left(1 + \left|\upsilon \right|^{q}\right)

with

q\in [p,pN/(N−1))

for

p⩽N−1

,

q\in [p,p+1)

for

p>N−1

. In particular, our results generalize earlier work where

\mathcal Av=0

reduced to

v=∇^su

for some

s\in ℕ

.

Des résultats de semi-continuité inférieure pour la convergence faible des mesures sont obtenues pour des fonctionnelles

\upsilon \in L^{1}\left(\Omega ;ℝ^{m}\right)\mapsto \int \limits_{\Omega }f\left(x,\upsilon \left(x\right)\right)\text{dx},

où les suites admissibles

\{v_n\}

satisfont un système d’EDP du 1er ordre et

\mathcal Av_n=0

. Nous supposons que

\mathcal A

a un rang constant, que

f

est

\mathcal A

-quasiconvexe et satisfait les conditions de croissance non standards

\frac{1}{C}\left(\left|\upsilon \right|^{p} - 1\right)⩽f\left(\upsilon \right)⩽C\left(1 + \left|\upsilon \right|^{q}\right)

où

q\in [p,pN/(N−1))

pour

p⩽N−1

,

q\in [p,p+1)

pour

p>N−1

. En particulier, nos résultats généralisent des résultats antérieurs où

\mathcal Av=0

se réduit à

v=∇^su

pour

s\in ℕ

.
Pseudoholomorphic strips in symplectisations I: Asymptotic behavior
Authors: Abbas Casim
Published: August 2004

This paper is part of a larger program, the investigation of the Chord Problem in three dimensional contact geometry. The main tool will be pseudoholomorphic strips in the symplectisation of a three dimensional contact manifold with two totally real submanifolds

L_0

,

L_1

as boundary conditions. The submanifolds

L_0

and

L_1

do not intersect transversally. The subject of this paper is to study the asymptotic behavior of such pseudoholomorphic strips.

Cet article fait partie d’un programme de travail plus grand : la recherche sur le problème de Chord en géometrie de contact en dimension trois. L’outil essentiel sont des bandes pseudo-holomorphes dans la symplectisation d’une variété contact à dimension trois avec la condition au bord suivante : les deux composantes de la frontière sont contenues dans deux sous-variétés totalement réelles

L_0

,

L_1

. Les variétés

L_0

et

L_1

ont des intersections non-transverses. Le sujet de cet article est l’étude du comportement asymptotique des solutions.
A Liouville theorem for solutions of the Monge–Ampère equation with periodic data
Authors: Li YanYan , Caffarelli L
Published: August 2004

A classical result of Jörgens, Calabi and Pogorelov states that any strictly convex smooth function

u

with

\det(D^2u)=\mathrm{constant}

in 

R^n

must be a quadratic polynomial. We establish the following extension: any strictly convex smooth function

u

with

\det(D^2u)

being 1-periodic in each variable must be the sum of a quadratic polynomial and a function which is 1-periodic in each variable. Given any positive periodic right-hand side, the existence and uniqueness of such solutions are well known.

Selon un théorème classique de Jörgens, Calabi et Pogorelov, toute solution régulière et strictement convexe de l’équation

\det(D^2u)=\mathrm{constante}

dans

R^n

doit être égale à un polynôme quadratique. On démontre le résultat suivant : si

u

une fonction régulière et strictement convexe telle que

\det(D^2u)

est 1-périodique par rapport à chaque variable, alors

u

est la somme d’un polynôme quadratique et d’une fonction 1-périodique par rapport à chaque variable. Étant donnée une fonction périodique et positive

f

, l’existence et l’unicité des solutions de

\det(D^2u)=f

est un problème bien connu.
A minimization problem associated with elliptic systems of FitzHugh–Nagumo type
Authors: Dancer E.N. , Yan Shusen
Published: August 2004

We consider a minimization problem associated with the elliptic systems of FitzHugh–Nagumo type and prove that the minimizer of this minimization problem has not only a boundary layer, but also may oscillate in a set of positive measure.

Nous étudions des solutions d’énergie minimale pour l’équation de FitzHugh–Nagumo. Nous prouvons que ces solutions ont plusieurs transitions rapids si la diffusion est petite.
Weakly stable multidimensional shocks
Authors: Coulombel Jean-François
Published: August 2004

We study the linear stability of multidimensional shock waves for systems of conservation laws in the case where Majda’s uniform stability condition is violated. The linearized problem is attacked using the “good unknown” of Alinhac. We prove an energy estimate and show that the solutions to the linearized problem have singularities localized along bicharacteristic curves originating from the boundary. The application to isentropic gas dynamics is detailed.

Nous étudions dans cet article la stabilité linéaire des ondes de choc multidimensionnelles qui ne sont pas uniformément stables au sens de Majda. Pour le problème linéarisé, nous montrons une estimation d’énergie sur la « bonne inconnue » d’Alinhac. En particulier, nous montrons que les solutions du problème linéarisé ont des singularités le long de courbes bicaractéristiques émanant du bord du domaine. Pour finir, nous traitons l’exemple de la dynamique des gaz isentropique.
Asymptotic behaviour and correctors for linear Dirichlet problems with simultaneously varying operators and domains
Authors: Dal Maso Gianni , Murat François
Published: August 2004

We consider a sequence of Dirichlet problems in varying domains (or, more generally, of relaxed Dirichlet problems involving measures in

\mathcal M_0^+(Ω)

) for second order linear elliptic operators in divergence form with varying matrices of coefficients. When the matrices

H

-converge to a matrix 

A^0

, we prove that there exist a subsequence and a measure

μ^0

in 

\mathcal M_0^+(Ω)

such that the limit problem is the relaxed Dirichlet problem corresponding to 

A^0

and 

μ^0

. We also prove a corrector result which provides an explicit approximation of the solutions in the

H^1

-norm, and which is obtained by multiplying the corrector for the

H

-converging matrices by some special test function which depends both on the varying matrices and on the varying domains.

Nous considérons une suite de problèmes de Dirichlet dans des ouverts variables (ou plus généralement une suite de problèmes de Dirichlet relaxés définis par des mesures de

\mathcal M_0^+(Ω)

pour des opérateurs elliptiques linéaires du deuxième ordre sous forme divergence avec des matrices de coefficients elles aussi variables. Quand les matrices

H

-convergent vers une matrice 

A^0

, nous démontrons qu’il existe une sous suite et une mesure 

μ^0

de

\mathcal M_0^+(Ω)

telles qu’à la limite on obtienne le problème de Dirichlet relaxé correspondant à 

A^0

et 

μ^0

. Nous démontrons également un résultat de correcteur qui donne une approximation explicite des solutions en norme 

H^1

; ce correcteur est obtenu en multipliant le correcteur pour la

H

-convergence des matrices par une fonction test spéciale qui dépend à la fois des matrices variables et des ouverts variables.
Inverse problem for a nonlinear Helmholtz equation
Authors: Jalade Emmanuel
Published: August 2004

This paper is devoted to the uniqueness of the coefficients

θ,φ\in L^∞(ℝ^3)

, and

ψ\in L^∞(ℝ^3,ℝ^3)

for the nonlinear Helmholtz equations

\begin{align*}
&−Δv(x)−k^2v(x)=θ(x)v(x)F(|v(x)|) \text{ and}\\
& −Δv(x)−k^2v(x)=(φ(x)v(x)+iψ(x).∇v(x))|∇v(x)|^r|v(x)|^s.
\end{align*}

For small values of

λ

, a solution

v

is uniquely constructed by adding a small outgoing perturbation to the plane wave

x→λe^{ikx.d}

, where

|d|=1

and

λ⩾0

. We can write

v=v(x,λ,d)=λe^{ikx.d}+u^s_∞(x/|x|,d,λ)e^{ik|x|}/|x|+O(1/|x|^2)

for large

|x|

. For a fixed

k>0

, we would like to prove that

θ, φ

and

\mathrm{div}ψ

can be uniquely reconstructed from the behaviour of

u^s_∞(x/|x|,d,λ)

as

λ→0

. We prove the uniqueness in this paper.

L’objet de ce papier est d’étudier l’unicité des coefficients

θ,φ\in L^∞(ℝ^3)

, et

ψ\in L^∞(ℝ^3,ℝ^3)

pour les Équations de Helmholtz non linéaires

\begin{align*}
&−Δv(x)−k^2v(x)=θ(x)v(x)F(|v(x)|) \text{ et}\\
&−Δv(x)−k^2v(x)=(φ(x)v(x)+iψ(x).∇v(x))|∇v(x)|^r|v(x)|^s.
\end{align*}

Quand

λ

est assez petit, on construit de manière unique une solution

v

en ajoutant à l’onde incidente plane

x→λe^{ikx.d}

(

|d|=1

,

λ⩾0

) une perturbation

k

-sortante. On peut ainsi écrire

v=v(x,λ,d)=λe^{ikx.d}+u^s_∞(x/|x|,d,λ)e^{ik|x|}/|x|+O(1/|x|^2)

quand

|x|→+∞

. Considérons que

k>0

est fixé. Le problème abordé dans ce papier est de montrer que

θ,φ

et

\mathrm{div}ψ

peuvent être construits de manière unique à partir du comportement asymptotique de

u^s_∞(x/|x|,d,λ)

quand

λ→0

. Nous démontrons l’unicité pour ce problème inverse, et développerons quelques aspects concernant la reconstruction.
The preventive effect of the convection and of the diffusion in the blow-up phenomenon for parabolic equations
Authors: Tersenov Alkis S
Published: August 2004

The goal of this paper is to investigate the role of the gradient term and of the diffusion coefficient in the preventing of the blow-up of the solution for semilinear and quasilinear parabolic problems.

Le but de cet article est de voir comment le terme de gradient et le coefficient de diffusion empêchent l’explosion des solutions des problèmes semilinéaires et quasilinéaires paraboliques.
Karyotype analyses and studies on the nuclear DNA content in 30 genotypes of potato (Solanum tuberosum) L.
Authors: Mohanty I.C. , Mahapatra D. , Mohanty S. , Das A.B.
Published: August 2004

The cytophotometric estimation of 4C DNA content, and karyotypic and somatic chromosome number analyses were carried out in 30 genotypes comprising seven cultivars and 23 advanced breeding lines of Solanum tuberosum. Detailed karyotype analysis revealed genotype specific chromosomal characteristics and structural alterations in chromosomes of the genome, with a rare phenomenon of aneusomatic (2n = 4x + 2 = 50) condition in cv.K. Chandramukhi. The origin of this variation could be attributed to mitotic non‐disjunction in the shoots giving rise to aneusomatic roots. Highly significant variations in the genome length, volume and total form percentage were noted at the cultivar level. The total chromosome length varied from 84.56 μm in cv.K. Pukhraj to 127.62 μm in MS/89‐60, with an average value of 100.94 μm ± 1.82. Total chromosome volume varied from 57.22 μm3 in MS/92‐1090 to 132.64 μm3 in JW‐160. Significant variations in the 4C DNA content (7.28–15.83 pg) were recorded at the cultivar level, with an exceptionally high DNA content (22.24 pg) in cv.K. Chandramukhi. This could be due to the aneusomatic condition of this genotype. Correlation studies revealed interdependence between the chromosomal and nuclear parameters of the genotypes. Structural alterations in the chromosomes, as well as loss or addition of highly repetitive sequences in the genome, caused variations in DNA content at the cultivar level. Variations in genomic structure and nuclear DNA content of the 48‐chromosome genotypes suggest a genetic drift during microevolution, leading to the development of new cultivars.
WD repeat‐containing mitotic checkpoint proteins act as transcriptional repressors during interphase
Authors: Yoon Young-Mee , Baek Kwan-Hyuck , Jeong Sook-Jung , Shin Hyun-Jin , Ha Geun-Hyoung , Jeon Ae-Hwa , Hwang Sang-Gu , Chun Jang-Soo , Lee Chang-Woo
Published: August 2004

WD repeats are implicated in protein–protein interactions and regulate a wide variety of cellular functions, including chromatin remodeling and transcription. The WD repeats of the Bub3 and Cdc20 kinetochore proteins are important for the physical interactions of these proteins with Mad2 and BubR1 to yield a kinetochore protein complex capable of delaying anaphase by inhibiting ubiquitin ligation via the anaphase‐promoting complex/cyclosome. Here, we show that Bub3 and Cdc20 form a complex with histone deacetylases; this interaction appears to confer transcriptional repressor activity in a heterologous DNA‐binding context. In addition, inhibition of Bub3 and Cdc20 expression significantly impairs interphase cell cycle. These results indicate that Bub3 and Cdc20 play additional roles in the integration of cell cycle arrest as transcriptional repressors.
Phenotypic selection and characterization of randomly produced non‐haemolytic mutants of the toxic sea anemone protein sticholysin II
Authors: Alegre-Cebollada Jorge , Lacadena Valle , Oñaderra Mercedes , Mancheño José M. , Gavilanes José G. , del Pozo Álvaro Martı́nez
Published: August 2004

A rapid screening method for haemolytic activity, using blood agar plates, has been developed to analyze randomly produced mutant variants of the pore‐forming protein sticholysin II (Stn II). Those exhibiting a reduced activity were selected and the DNA corresponding to each Stn II variant sequenced. Once the mutation produced was determined, protein variants were isolated and characterized in terms of structure (circular dichroism spectra and thermal stability) and haemolytic activity. Three single mutation protein variants, at residues K19, F106 and Y111, showed a significantly decreased haemolytic activity while their thermostability was identical to that of the wild‐type protein. Considering the obtained data and based on the three‐dimensional structure of the protein, the role of these residues on the mechanism of haemolysis has been analyzed.
Assembly of nicotinic α7 subunits in Xenopus oocytes is partially blocked at the tetramer level
Authors: Nicke Annette , Thurau Heike , Sadtler Sven , Rettinger Jürgen , Schmalzing Günther
Published: August 2004

The assembly of nicotinic α1β1γδ, α3β4, and α7 receptors and 5‐hydroxytryptamine 3A (5HT3A) receptors was comparatively evaluated in Xenopus oocytes by blue native PAGE analysis. While α1βγδ subunits, α3β4 subunits, and 5HT3A subunits combined efficiently to pentamers, α7 subunits existed in various assembly states including trimers, tetramers, pentamers, and aggregates. Only α7 subunits that completed the assembly process to homopentamers acquired complex‐type carbohydrates and appeared at the cell surface. We conclude that Xenopus oocytes have a limited capacity to guide the assembly of α7 subunits, but not 5HT3A subunits to homopentamers. Accordingly, ER retention of imperfectly assembled α7 subunits rather than inefficient routing of fully assembled α7 receptors to the cell surface limits surface expression levels of α7 nicotinic acetylcholine receptors.
Effect of Shifting Policies on Traditional Birth Attendant Training
Authors: Kruske Sue , Barclay Lesley
Published: August 2004

Traditional birth attendant (TBA) training commenced in many places in the non‐Western world in the 1970s, supported by the World Health Organization and other funding bodies. By 1997, senior policy makers decided to refocus priorities on the provision of “skilled attendants” to assist birthing women. The definition of skilled attendants excluded TBAs and resulted in the subsequent withdrawal of funding for TBA training globally. A review of the health and sociological literature and international policy documents that address TBA training revealed how international policy and professional orientation are reflected in education programs designed for the TBA. Policy makers risk ignoring the important cultural and social roles TBAs fulfill in their local communities and fail to recognize the barriers to the provision of skilled care. The provision of skilled attendants for all birthing women cannot occur in isolation from TBAs who in themselves are also highly skilled. This article argues a legitimacy of alternative worldviews and acknowledges the contribution TBAs make to childbearing women across the world.
Determinants of Women's Decision Making on Whether to Treat Nausea and Vomiting of Pregnancy Pharmacologically
Authors: Baggley Anne , Navioz Yvette , Maltepe Caroline , Koren Gideon , Einarson Adrienne
Published: August 2004

Nausea and vomiting of pregnancy (NVP) affects up to 80% of all women to some degree during their pregnancies. Diclectin (doxy lamine and pyridoxine [vitamin B6]) has been on the Canadian market for many years and is indicated as the drug of choice for the treatment of NVP. However, some women choose not to treat NVP with pharmacologic measures, perhaps due to a persistent fear of teratogenic risk. The objective of this study was to determine the factors that influence a woman's decision not to treat NVP with pharmacologic measures. Fifty‐nine women recruited from the Motherisk Nausea and Vomiting Helpline completed a questionnaire. All were informed that Diclectin was considered safe for use during pregnancy. At a follow‐up telephone call, 34% were not using any pharmacologic treatment, and of those who were taking the drug, 26% were using less than the recommended dose. Reasons cited for not using the medication were insufficient safety data, preference for non‐pharmacologic methods, and being made to feel uncomfortable by the physician. Of the women who did use Diclectin, the most convincing reassuring information that it was safe to use came from friends and family. Many other factors play a large role in a women's decision making.
Modulation of vertebral and tibial growth by compression loading: Diurnal versus full‐time loading
Authors: Stokes Ian A. , Gwadera Jodie , Dimock Abigail , Farnum Cornelia E. , Aronsson David D.
Published: August 2004

Purpose: This study was designed to determine whether the amount of endochondral growth response to mechanical compression and the underlying growth mechanism differed with night‐time or day‐time loading, relative to full‐time loading.

Methods: Mechanical compression (nominally 0.1 MPa stress) was applied across tibial and tail vertebral growth plates of growing Sprague–Dawley rats. Four groups of animals (five per group) were used: 24/24 h (full‐time loading); 12/24 h (day‐loading); 12/24 h (night‐loading); and 0/24 h (sham instrumented). Contralateral tibiae and adjacent vertebrae served as within‐animal controls. The animals were euthanized after eight days. Growth plates were processed for quantitative histology to measure 24‐h growth, total and BrdU‐positive proliferative zone chondrocyte counts, and hypertrophic chondrocytic enlargement in the growth direction.

Results: Growth as a percentage of within‐animal control averaged 82% (full‐time); 93% (day‐loading); 90% (night‐loading); 100% (sham) for vertebrae. For proximal tibiae it averaged 70% (full‐time); 84% (day‐loading); 86% (night‐loading); 89% (sham). Reduced amount of hypertrophic chondrocytic enlargement explained about half of this effect in full‐time loaded growth plates, but was not significantly altered in half‐time loaded growth plates. The remaining variation in growth was apparently explained by reduced total numbers of proliferative zone chondrocytes. These findings indicate that sustained compression loading suppressed growth more than intermittent loading at both anatomical locations. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Behavior of lithium and its isotopes during weathering of Hawaiian basalt
Authors: Huh Youngsook , Chan Lui‐Heung , Chadwick Oliver A.
Published: August 2004

We examined the pedogenic behavior of lithium (Li) and its isotopes in Hawaii by sampling same‐age lava flows under mean annual rainfall ranging from 18 to 300 cm. Lithium concentrations in these soils vary from 1 to 29 ppm. Whereas Na, K, and Ca are completely leached from the soil at the most humid and severely weathered site, Li, Mg, Si, and Al show significant retention due to their association with secondary clay minerals. In these soils, allochthonous Li delivered in marine and mineral aerosol mixes with basalt‐derived Li, modifying the isotopic composition of the Li pool. The ability of soil to retain Li is related to its effective cation exchange capacity, which in turn is governed by rainfall and leaching intensity and their resulting effect on mineralogy. Lithium isotope ratios have a large range (δ7Li of −0.4 to 14‰), well beyond the intershield or temporal variation of the lavas of Hawaiian volcanoes (2.5 to 5.7‰). The most unweathered samples have δ7Li (∼5–6‰) comparable to that of Mauna Kea and Mauna Loa lavas. The Li concentrations and isotope ratios together suggest that in arid to subhumid sites there is a net addition of isotopically heavier lithium from marine aerosol but that under greater rainfall there is a net loss of Li, and isotopically light Li is preferentially retained. Thus, during incongruent weathering of primary minerals, Li, especially 6Li, is adsorbed and sequestered by the clay mineral fraction of high cation exchange capacity soils in drier regions but lost from highly weathered, low cation exchange capacity acidic soils in the wetter regions.
Northward and southward migrations of frontal zones during the past 40 kyr in the Kuroshio‐Oyashio transition area
Authors: Harada Naomi , Ahagon Naokazu , Uchida Masao , Murayama Masafumi
Published: August 2004

The variation of sea surface temperature (SST) in the Kuroshio‐Oyashio transition area and the Okhotsk Sea during the last 40 kyr was estimated using long‐chain unsaturated alkyl ketones (alkenones). The temperature difference between the present and the last glacial period was about 5°–6°C in the Kuroshio‐Oyashio transition area, slightly larger than the 4°C previously reported. Moreover, alkenones were not detected before 18 kyr B.P. in or near the Okhotsk Sea, perhaps because of nearly year‐round sea‐ice expansion, which would have prevented the growth of alkenone producers, or because alkenones were less well preserved in surface sediments during the glacial period. The northward and southward migrations of frontal zones were evaluated using differences in alkenone temperatures between stations located in the vicinity of the Subarctic Front (SAF), Subarctic Boundary (SAB), and Kuroshio Bifurcation Front (KBF). All three frontal zones migrated southward during the glacial period, compared with their present positions, and their relative positions were different between the Holocene and glacial periods. In particular, the distance between the SAF and the SAB was reduced during the glacial period compared with at present. The northward and southward migration of the frontal zones may relate to both mid to low atmospheric circulation and polar atmospheric circulation.
The role of the air‐sea temperature difference in air‐sea exchange
Authors: Phillips Leon F.
Published: August 2004

Recent laboratory measurements have shown that the stationary‐state vapor pressures of aniline and n‐heptanol are enhanced by the application of a positive temperature gradient in the vapor, that the vapor pressure of water over 50 percent sulfuric acid is enhanced by a positive temperature gradient and diminished by a negative temperature gradient, and that values of the Onsager heat of transport derived from these measurements are of similar magnitude to the latent heats of vaporization. When the vapor gap over which the temperature difference is applied is less than about 0.8 mean free paths, the liquid behaves as though its surface were at the temperature close to that of the gas on the other side of the Knudsen layer. These results are discussed in relation to field measurements of the rate of air‐sea exchange of carbon dioxide.
Forced expression of the cyclin B1–CDC2 complex induces proliferation in adult rat cardiomyocytes
Authors: BICKNELL Katrina A. , COXON Carmen H. , BROOKS Gavin
Published: August 2004

Repair of the mature mammalian myocardium following injury is impaired by the inability of the majority of cardiomyocytes to undergo cell division. We show that overexpression of the cyclin B1–CDC2 (cell division cycle 2 kinase) complex re-initiates cell division in adult cardiomyocytes. Thus strategies targeting the cyclin B1–CDC2 complex might re-initiate cell division in mature cardiomyocytes in vivo and facilitate myocardial regeneration following injury.
Transthyretin interacts with the lysosome-associated membrane protein (LAMP-1) in circulation
Authors: CHANG Melissa H. Y. , HUA Chi T. , ISAAC Elizabeth L. , LITJENS Tom , HODGE Greg , KARAGEORGOS Litsa E. , MEIKLE Peter J.
Published: August 2004

LAMP-1 (lysosome-associated membrane protein), a major glycoprotein present in the lysosomal membrane, constitutes up to 50% of total membrane proteins. LAMP-1, expressed at the plasma membrane, is reported to be the major molecule expressing the sialyl-Lewis X antigen. Two forms of LAMP-1 exist; the full-length LAMP-1 [LAMP-1 (+Tail)] has a highly glycosylated lumenal domain, a membrane-spanning domain and a short cytoplasmic tail, and the truncated LAMP-1 [LAMP-1 (−Tail)] contains only the lumenal domain. Soluble LAMP-1 (±Tail) has been reported in circulation. LAMP-1 at the cell surface has been shown to interact with E-selectin and galectin and is proposed to function in cell–cell interactions. However, the functional role(s) of soluble LAMP-1 in circulation is unclear. To investigate the functional role of soluble LAMP-1 in circulation, recombinant LAMP-1 (−Tail) and LAMP-1 (+Tail) were produced in HT1080 cells. Two immune-quantification assays were developed to distinguish between the LAMP-1 forms. The interaction and aggregation properties of the different LAMP-1 forms were investigated using the immune-quantification assays. Only LAMP-1 (+Tail) was found to aggregate and interact with plasma proteins. Plasma proteins that interact with LAMP-1 were isolated by affinity chromatography with either the recombinant LAMP-1 (−Tail) or a synthesized peptide consisting of the 14 amino acids of the LAMP-1 cytoplasmic tail. Transthyretin was found to interact with the cytoplasmic tail of LAMP-1. Transthyretin exists as a homotetramer in plasma, as such may play a role in the aggregation of LAMP-1 in circulation.