bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.

Résumé
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

.

Résumé
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.

Résumé

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.

Résumé

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.

Résumé
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.

Résumé
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.

Résumé

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.

Résumé

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.

Résumé
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

AbstractThe 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.
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

AbstractPurpose: 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.
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.
Characterization of bromosulphophthalein binding to human glutathione S-transferase A1-1: thermodynamics and inhibition kinetics
Authors: KOLOBE Doris , SAYED Yasien , DIRR Heini W. 
Published: August 2004

In addition to their catalytic functions, GSTs (glutathione S-transferases) bind a wide variety of structurally diverse non-substrate ligands. This ligandin function is known to result in the inhibition of catalytic function. The interaction between hGSTA1-1 (human class Alpha GST with two type 1 subunits) and a non-substrate anionic ligand, BSP (bromosulphophthalein), was studied by isothermal titration calorimetry and inhibition kinetics. The binding isotherm is biphasic, best described by a set of two independent sites: a high-affinity site and a low-affinity site(s). The binding stoichiometries for these sites are 1 and 3 molecules of BSP respectively. BSP binds to the high-affinity site 80 times more tightly (Kd=0.12 μM) than it does to the low-affinity site(s) (Kd=9.1 μM). Binding at these sites is enthalpically and entropically favourable, with no linkage to protonation events. Temperature- and salt-dependent studies indicate the significance of hydrophobic interactions in the binding of BSP, and that the low-affinity site(s) displays low specificity towards the anion. Binding of BSP results in the release of ordered water molecules at these hydrophobic sites, which more than offsets unfavourable entropic changes during binding. BSP inhibition studies show that the binding of BSP to its high-affinity site does not inhibit hGSTA1-1. This site, located near Trp-20, may be related to the buffer-binding site observed in GSTP1-1. The low-affinity-binding site(s) for BSP is most probably located at or near the active site of hGSTA1-1. Binding to this site(s) results in non-competitive inhibition with respect to CDNB (1-chloro-2,4-dinitrobenzene) (KiBSP=16.8±1.9 μM). Given the properties of the H site and the relatively small size of the electrophilic substrate CDNB, it is plausible that the active site of the enzyme can simultaneously accommodate both BSP and CDNB. This would explain the non-competitive behaviour of certain inhibitors that bind the active site (e.g. BSP).
Structural requirements of the glucocorticoid-response unit of the carbamoyl-phosphate synthase gene
Authors: SCHONEVELD Onard J. L. M. , GAEMERS Ingrid C. , DAS Atze T. , HOOGENKAMP Maarten , RENES Johan , RUIJTER Jan M. , LAMERS Wouter H. 
Published: August 2004

The GRU (glucocorticoid-response unit) within the distal enhancer of the gene encoding carbamoyl-phosphate synthase, which comprises REs (response elements) for the GR (glucocorticoid receptor) and the liver-enriched transcription factors FoxA (forkhead box A) and C/EBP (CCAAT/enhancer-binding protein), and a binding site for an unknown protein denoted P3, is one of the simplest GRUs described. In this study, we have established that the activity of this GRU depends strongly on the positioning and spacing of its REs. Mutation of the P3 site within the 25 bp FoxA–GR spacer eliminated GRU activity, but the requirement for P3 could be overcome by decreasing the length of this spacer to ≤12 bp, by optimizing the sequence of the REs in the GRU, and by replacing the P3 sequence with a C/EBPβ sequence. With spacers of ≤12 bp, the activity of the GRU depended on the helical orientation of the FoxA and GR REs, with highest activities observed at 2 and 12 bp respectively. Elimination of the 6 bp C/EBP–FoxA spacer also increased GRU activity 2-fold. Together, these results indicate that the spatial positioning of the transcription factors that bind to the GRU determines its activity and that the P3 complex, which binds to the DNA via a 75 kDa protein, functions to facilitate interaction between the FoxA and glucocorticoid response elements when the distance between these transcription factors means that they have difficulties contacting each other.
Characterization of the first non-insect invertebrate functional angiotensin-converting enzyme (ACE): leech TtACE resembles the N-domain of mammalian ACE
Authors: RIVIÈRE Guillaume , MICHAUD Annie , DELOFFRE Laurence , VANDENBULCKE Franck , LEVOYE Angélique , BRETON Christophe , CORVOL Pierre , SALZET Michel , VIEAU Didier 
Published: August 2004

Angiotensin-converting enzyme (ACE) is a zinc metallopeptidase that plays a major role in blood homoeostasis and reproduction in mammals. In vertebrates, both transmembrane and soluble ACE, containing one or two homologous active sites, have been characterized. So far, several ACEs from invertebrates have been cloned, but only in insects. They are soluble and display a single active site. Using biochemical procedures, an ACE-like activity was detected in our model, the leech, Theromyzon tessulatum. Annelida is the most distant phylum in which an ACE activity has been observed. To gain more insight into the leech enzyme, we have developed a PCR approach to characterize its mRNA. The approx. 2 kb cDNA has been predicted to encode a 616-amino-acid soluble enzyme containing a single active site, named TtACE (T. tessulatum ACE). Surprisingly, its primary sequence shows greater similarity to vertebrates than to invertebrates. Stable in vitro expression of TtACE in transfected Chinese-hamster ovary cells revealed that the leech enzyme is a functional metalloprotease. As in mammals, this 79 kDa glycosylated enzyme functions as a dipeptidyl carboxypeptidase capable of hydrolysing angiotensin I to angiotensin II. However, a weak chloride inhibitory effect and acetylated N-acetyl-SDKP (Ac SDAcKP) hydrolysis reveal that TtACE activity resembles that of the N-domain of mammalian ACE. In situ hybridization shows that its cellular distribution is restricted to epithelial midgut cells. Although the precise roles and endogenous substrates of TtACE remain to be identified, characterization of this ancestral peptidase will help to clarify its physiological roles in non-insect invertebrate species.