bluuebunny/crossref_metadata_2025 huggingface dataset:
Constitutive expression of a small heat‐shock protein confers cellular thermotolerance and thermal protection to the photosynthetic apparatus in cyanobacteria
Authors: Nakamoto Hitoshi , Suzuki Nobuaki , Roy Sanjit Kumer
Published: July 2002

The role of a small heat‐shock protein (Hsp) in the acquisition of thermotolerance in cyanobacteria was investigated. Synechococcus sp. PCC 7942 was transformed with an expression vector carrying the coding sequence of the hspA gene encoding a small heat‐shock protein from Synechococcus vulcanus under the control of the tac promoter. The transformant which was shown to constitutively express HspA displayed improved viability compared with the reference strain upon transfer from 30 to 50°C in the light. When the heat shock was given in darkness, the survival rate in the reference strain increased greatly, approaching a level similar to that for the HspA expressing strain after heat shock in the light. Expression of HspA increased thermal resistance of photosystem II (PS II) and protected phycocyanin from heat‐induced photobleaching. Our results are indicative of a central role for HspA in amelioration of the harmful effect of light during heat stress and identified the possible sites of action of the small Hsp in vivo to be the PS II complex and the light‐harvesting phycobilisomes.
Defining the minimal structural requirements for partial agonism at the type I myo‐inositol 1,4,5‐trisphosphate receptor
Authors: Wilcox Robert A. , Fauq Abdul , Kozikowski Alan P. , Nahorski Stefan R.
Published: July 2002

The novel synthetic analogues d‐3‐fluoro‐myo‐inositol 1,5‐bisphosphate‐4‐phosphorothioate, [3F‐Ins(1,5)P2‐4PS], d‐3‐fluoro‐myo‐inositol 1,4‐bisphosphate‐5‐phosphorothioate [3F‐Ins(1,4)P2‐5PS], and d‐3‐fluoro‐myo‐inositol 1‐phosphate‐4,5‐bisphosphorothioate [3F‐Ins(1)P‐(4,5)PS2] were utilised to define the structure‐activity relationships which could produce partial agonism at the Ca2+ mobilising myo‐inositol 1,4,5‐trisphosphate [Ins(1,4,5)P3] receptor. Based on prior structure‐activity data we hypothesised that the minimal structural requirements for Ins(1,4,5)P3 receptor partial agonism, were phosphorothioate substitution of the crucial vicinal 4,5‐bisphosphate pair accompanied by another structural perturbation, such fluorination of 3‐position of the myo‐inositol ring. All the analogues fully displaced [3H]Ins(1,4,5)P3 from a single Ins(1,4,5)P3 binding site in pig cerebellar membranes [3F‐Ins(1,5)P2‐4PS (IC50=26 nM), 3F‐Ins(1,4)P2‐5PS (IC50=80 nM) and 3F‐Ins(1)P‐(4,5)PS2 (IC50=109 nM) cf. Ins(1,4,5)P3 (IC50=11 nM)]. In contrast, 3F‐Ins(1,5)P2‐4PS (IC50=424 nM) and 3F‐Ins(1,4)P2‐5PS (IC50=3579 nM) were weak full agonists at the Ca2+ mobilising Ins(1,4,5)P3 receptor of permeabilised SH‐SY5Y neuroblastoma cells, being respectively 4‐ and 36‐fold less potent than Ins(1,4,5)P3 (EC50=99 nM). While 3F‐Ins(1)P‐(4,5)PS2 (EC50=11345 nM) was a partial agonist releasing only 64.3±1.9% of the Ins(1,4,5)P3‐sensitive intracellular Ca2+ pools. 3F‐Ins(1)P‐(4,5)PS2 was unique among the Ins(1,4,5)P3 receptor partial agonists so far identified in having a relatively high affinity for the Ins(1,4,5)P3 binding site, accompanied by a significant loss of intrinsic activity for Ca2+ mobilisation. This improved affinity was probably due to the retention of the 1‐position phosphate, which enhances interaction with the Ins(1,4,5)P3 receptor. 3F‐Ins(1)P‐(4,5)PS2 may be an important lead compound for the development of efficient Ins(1,4,5)P3 receptor antagonists © 1997 Federation of European Biochemical Societies. All rights reserved.
Ribonuclease T1 has different dimensions in the thermally and chemically denatured states: a dynamic light scattering study
Authors: Gast Klaus , Zirwer Dietrich , Damaschun Hilde , Hahn Ulrich , Müller-Frohne Marlies , Wirth Matthias , Damaschun Gregor
Published: July 2002

© 1997 Federation of European Biochemical Societies.
Calcium‐ and pH‐linked oligomerization of sorcin causing translocation from cytosol to membranes
Authors: Zamparelli Carlotta , Ilari Andrea , Verzili Daniela , Vecchini Paola , Chiancone Emilia
Published: July 2002

Sorcin, a cytosolic calcium‐binding protein containing a pair of EF‐hand motifs, undergoes a Ca2+‐dependent translocation to the cell membrane. The underlying conformational change is similar at pH 6.0 and 7.5 and consists in an increase in overall hydrophobicity that involves the aromatic residues and in particular the two tryptophan residues which become less exposed to solvent. The concomitant association from dimers to tetramers indicates that the tryptophan residues, which are located between the EF‐hand sites, become buried at the dimer–dimer interface. Ca2+‐bound sorcin displays a striking difference in solubility as a function of pH that has been ascribed to the formation of calcium‐stabilized aggregates.
Spectral and photochemical properties of borohydride‐treated D1‐D2‐cytochromeb‐559 complex of photosystem II
Authors: Shkuropatov Anatoli Ya , Khatypov Ravil A , Volshchukova Tatyana S , Shkuropatova Valentina A , Owens Thomas G , Shuvalov Vladimir A
Published: July 2002

The D1‐D2‐cytochromeb‐559 reaction center complex of photosystem II with an altered pigment composition was prepared from the original complex by treatment with sodium borohydride (BH−4). The absorption spectra of the modified and original complexes were compared to each other and to the spectra of purified chlorophyllaand pheophytina(Pheoa) treated with BH−4in methanolic solution. The results of these comparisons are consistent with the presence in the modified complex of an irreversibly reduced Pheoamolecule, most likely 131‐deoxo‐131‐hydroxy‐Pheoa, replacing one of the two native Pheoamolecules present in the original complex. Similar to the original preparation, the modified complex was capable of a steady‐state photoaccumulation of Pheo−and P680+. It is concluded that the pheophytinamolecule which undergoes borohydride reduction is not involved in the primary charge separation and seems to represent a previously postulated photochemically inactive Pheoamolecule. The Qyand Qxtransitions of this molecule were determined to be located at 5°C at 679.5–680 nm and 542 nm, respectively.
Rewiring a receptor: negative output from positive input
Authors: Taylor Barry L , Johnson Mark S
Published: July 2002

A point mutation or covalent modification in bacterial chemotaxis receptors causes bacteria to be repelled by attractants, and attracted to repellents. The variety of conditions causing inverse responses suggest that the signal transduction mechanism in receptors can be readily rewired to elicit inverse responses. A model is presented in which the orientation of a critical residue with respect to an active site determines whether the receptor produces normal or inverted signals. The model is consistent with observed responses and can be generalized to include receptors in other signal transduction systems.
Differences in chain length distribution of inulin fromCynara scolymusandHelianthus tuberosusare reflected in a transient plant expression system using the respective 1‐FFT cDNAs
Authors: Hellwege Elke M , Raap Maik , Gritscher Dominique , Willmitzer Lothar , Heyer Arnd G
Published: July 2002

A newly isolated cDNA clone,Cy3, encoding the fructan fructan 1‐fructosyltransferase (1‐FFT) from artichoke was expressed using tobacco protoplasts as expression system. Analysis of the inulin molecules synthesized upon incubation of protoplast extracts with a mixture of oligofructans (DP3–5) shows the production of inulins with a degree of polymerization (DP) of up to 23, whereas parallel experiments performed using a 1‐FFT cDNA from Jerusalem artichoke led to the production of fructans with a DP of up to only 12. The results of in vitro fructan synthesis catalyzed by transiently expressed enzymes therefore reflect the difference of in vivo fructan composition of Jerusalem artichoke (MDP=8–10) and artichoke (MDP=65). These data suggest that the fructan pattern in a given species is mainly defined by the enzymatic characteristics of 1‐FFT.
Identification of a novel human phosphatidic acid phosphatase type 2 isoform
Authors: Hooks Shelley B. , Ragan Seamus P. , Lynch Kevin R.
Published: July 2002

Two human isoforms of membrane associated phosphatidic acid phosphatase have been described (PAP‐2a and ‐2b), and both enzymes have been shown to have broad substrate specificity and wide tissue distribution [Kai et al., J. Biol. Chem. 272 (1997) 24572–24578]. With this report we describe a third isoform, PAP‐2c, that we found by searching the database of expressed sequence tags (dbEST) with PAP‐2a and PAP‐2b sequences. Key structural features described previously in PAP‐2a and ‐2b, including the glycosylation site, putative transmembrane domains, and the proposed catalytic site, are conserved in the novel phosphatase. The kinetics of the three enzymes were compared using as substrates phosphatidic acid, lysophosphatidic acid, and N‐oleoyl ethanolamine phosphatidic acid. K
m values for each of the substrates, respectively, were (in μM) PAP‐2a: 98, 170, 116; PAP‐2b: 100, 110, 56; and PAP‐2c: 150, 340, 138. Expression of PAP‐2c mRNA is more restricted than the two previously described isoforms.
Overexpression of nucleoside diphosphate kinases induces neurite outgrowth and their substitution to inactive forms leads to suppression of nerve growth factor‐ and dibutyryl cyclic AMP‐induced effects in PC12D cells
Authors: Ishijima Yasushi , Shimada Nobuko , Fukuda Mitsugu , Miyazaki Hidetaka , Orlov Nicolay Ya , Orlova Tatiana G , Yamada Takeshi , Kimura Narimichi
Published: July 2002

Whether nucleoside diphosphate kinase (NDPK) is involved in neuronal differentiation was investigated with special reference to its enzyme activity. Neurite outgrowth of PC12D cells induced by nerve growth factor or a cyclic AMP analog was suppressed to some extent when inactive NDPKs (the active site histidine 118 was replaced with alanine), not active forms, were transiently overexpressed. This suppression was more definite in their stably expressed clones. NDPKβ‐transfected clones and, to a lesser extent, NDPKα‐transfected clones, but not inactive NDPK‐transfected clones, extended neurites without differentiation inducers. These results imply that NDPKs may play a role by exerting their enzyme activity during differentiation of PC12 cells.
A critical comparison of the hemolytic and fungicidal activities of cationic antimicrobial peptides
Authors: Helmerhorst Eva J , Reijnders Ingrid M , van 't Hof Wim , Veerman Enno C.I , Nieuw Amerongen Arie V
Published: July 2002

The hemolytic and fungicidal activity of a number of cationic antimicrobial peptides was investigated. Histatins and magainins were inactive against human erythrocytes and Candida albicans cells in phosphate buffered saline, but displayed strong activity against both cell types when tested in 1 mM potassium phosphate buffer supplemented with 287 mM glucose. The HC50/IC50 ratio, indicative of the therapeutic index, was about 30 for all peptides tested. PGLa was most hemolytic (HC50=0.6 μM) and had the lowest therapeutic index (HC50/IC50=0.5). Susceptibility to hemolysis was shown to increase with storage duration of the erythrocytes and also significant differences were found between blood collected from different individuals. In this report, a sensitive assay is proposed for the testing of the hemolytic activities of cationic peptides. This assay detects subtle differences between peptides and allows the comparison between the hemolytic and fungicidal potency of cationic peptides.
Membrane potential stabilizes the O intermediate in liposomes containing bacteriorhodopsin
Authors: Kalaidzidis Inna V , Belevich Ilya N , Kalaidzidis Yannis L , Kaulen Andrey D
Published: July 2002

In the bacteriorhodopsin‐containing proteoliposomes, a laser flash is found to induce formation of a bathointermediate decaying in several seconds, the difference spectrum being similar to the purple–blue transition. Different pH buffers do not affect the intermediate, whereas an uncoupler, gramicidin A, and lipophilic ions accelerate decay of the intermediate or inhibit its formation. In the liposomes containing E204Q bacteriorhodopsin mutant, formation of the intermediate is suppressed. In the wild‐type bacteriorhodopsin liposomes, the bathointermediate formation is pH‐independent within the pH 5–7 range. The efficiency of the long‐lived O intermediate formation increases at a low pH. In the wild‐type as well as in the E204Q mutant purple membrane, the O intermediate decay is slowed down at slightly higher pH values than that of the purple–blue transition. It is suggested that the membrane potential affects the equilibrium between the bacteriorhodopsin ground state (Glu‐204 is protonated and Asp‐85 is deprotonated) and the O intermediate (Asp‐85 is protonated and Glu‐204 is deprotonated), stabilizing the latter by changing the relative affinity of Asp‐85 and Glu‐204 to H+. At a low pH, protonation of a proton‐releasing group (possibly Glu‐194) in the bacteriorhodopsin ground state seems to prevent deprotonation of the Glu‐204 during the photocycle. Thus, all protonatable residues of the outward proton pathway should be protonated in the O intermediate. Under such conditions, membrane potential stabilization of the O intermediate in the liposomes can be attributed to the direct effect of the potential on the pK value of Asp‐85.
Functional expression of His‐tagged sensory rhodopsin I inEscherichia coli
Authors: Schmies Georg , Chizhov Igor , Engelhard Martin
Published: July 2002

Sensory rhodopsin I (SRI) fromHalobacterium salinarumwas functionally expressed inEscherichia coliand subsequently purified to homogeneity using a C‐terminal His‐tag anchor. Yields of 3–4 mg SRI/l cell culture can be obtained. The absorption and photocycle properties of SRI were similar if not indistinguishable from those of the homologously expressed SRI. A global fit analysis of the photocycle data and the calculation of the spectra of states provided strong evidence for the existence of an N‐like intermediate.
Over‐the‐counter use of oral contraceptives in Kuwait
Authors: Shah M.A. , Shah N.M. , Al‐Rahmani E. , Behbehani J. , Radovanovic Z.
Published: July 2002

Oral contraceptive pills (OCPs) are available over‐the‐counter (OTC) in Kuwait, and constitute a leading method for spacing and limiting children. Data from a nationally representative survey of Kuwaiti women are used to examine OTC use of OCPs. One‐fourth of the women initiated use without consulting a doctor, and 50% bought OCPs from the pharmacy. No socioeconomic or demographic differences were found between those who consulted a physician, implying that women of different background have similar accessibility to the physician. Using multivariate analysis, the odds of consulting a physician were found to be significantly lower for women who first bought OCPs directly from the commercial pharmacy. The duration of first time OCP use did not differ according to physician consultation. It is concluded that OTC availability of OCPs has many advantages and prevents unwanted pregnancy. However, there is a need for better packaging and instructions that would enable high‐risk women to identify themselves and to use OCPs under physician supervision.
Prognostic factors related to cervical cancer survival in Mexican women
Authors: Flores‐Luna L , Salazar‐Martinez E , Escudero‐De los Rios P , Gonzalez‐Lira G , Zamora‐Muñoz S , Lazcano‐Ponce E
Published: July 2002

Objective: To identify prognostic survival factors among Mexican women with cervical cancer.Methods: A total of 378 women with cervical cancer admitted from 1984 to 1996 to our referral hospital were evaluated, using survival analysis (Kaplan–Meier and Cox proportional hazards method). We designed a symptom index which included asymptomatic conditions, severity of symptoms and comorbidity.Results: Overall 5‐year survival was 66.6%. The shortest survival time was for FIGO stage IV (21.5%,P<0.001) and adenosquamous histologic type (53.1%,P=0.15). The main prognostic factors were primary symptoms (RR, 2.6; 95% CI, 1.02–6.66); systemic symptoms (RR, 3.3; 95% CI, 1.23–9.01); FIGO stage IV (RR, 5.5; 95% CI, 2.36–12.96); and oncogenic symptoms (prognostic comorbidity present) (RR, 2.3; 95% CI, 1.08–4.89).Conclusions: Our findings show that clinical stage and several types of symptoms influence CC survival. This present strategy to assess morphological and clinical characteristics may be a more accurate indicator of survival rate and potentially an efficient indicator of new therapeutic alternatives.
Cyclofem®/Cyclo‐ProveraTM: Emerging countries' perspective
Authors: Garza‐Flores J.J
Published: July 2002

Cyclo‐ProveraTM, the original name of the combination of 25 mg medroxyprogesterone acetate and 5 mg estradiol cypionate, later known as Cyclofem® and hereafter referred to MPA/E2C, has proven its use‐effectiveness (pregnancy rate less than 1%) in routine service delivery conditions. Overall, the life‐table discontinuation rates at 1 year ranged from 33.5% to 71.8%. Only a third of total discontinuations were attributable to the injectable contraceptive method, thus raising the importance of service delivery issues related to its continued use. The results of introductory trials in Mexico, Indonesia, Thailand, Tunisia, Jamaica and, more recently, Brazil, Colombia, Chile and Peru have demonstrated that MPA/E2C is a highly effective contraceptive that could be offered as an alternative to current fertility regulation methods for many women around the world. In addition, the results of studies were the basis for the approval of MPA/E2C by local health authorities and its inclusion in the Ministries of Health Family Planning Programs.
Prognosis‐predicting system based on factors related to survival of cervical carcinoma
Authors: Yuan Chiou‐Chung , Wang Peng‐Hui , Lai Chiung‐Ru , Yen Ming‐Shyen , Chen Chih‐Yu , Juang Chi‐Mon
Published: July 2002

Objective: To establish a different category system based on grouping of the risk factors in patients with cervical smear.Methods:Univariate and multivariate analyses of factors associated with survival time were performed in 443 patients with stage Ib–IIa squamous cell carcinoma (SCC) from 1985 to 1989.Results:Univariate analysis showed that parametrial extension, bulky tumor size (≥4 cm), uterine body involvement, poor differentiation and pelvic lymph node (LN) metastasis were prognostically significant. However, by multiple regression method, only LN metastasis, deep stromal invasion (DSI), and poor differentiation (PD) were significantly related to the patient's survival time with risk ratios of 2.78, 2.61 and 1.52, respectively. A prognosis‐predicting system was established on the basis of these simplified factors: groups of high, intermediate, low and very low‐risks, obtained survival rates of 93–96%, 77%, 51% and 25–37%, respectively.Conclusions:Using this simple model, cervical carcinomas can be classified prognostically for predicting 5‐year‐survival rates, and for risk‐guided therapy in the future.
Collaborative research and development on mifepristone in China to reduce unwanted pregnancies and recourse to abortion
Authors: Duncan G.W.
Published: July 2002

A program proposed and executed by The Concept Foundation and funded by the Rockefeller Foundation demonstrates the feasibility of using private/public‐sector collaboration for making mifepristone widely available. The application of mifepristone to emergency, luteal phase and menstrual induction contraception is being assessed in clinical research programs conducted in accordance with international standards for good clinical research. Opportunities for introduction of mifepristone in developing countries are being pursued using mifepristone produced in China in accordance with international standards of good manufacturing practice.
An integrated benchmarking approach to distribution center performance using DEA modeling
Authors: Ross Anthony , Droge Cornelia
Published: July 2002

This research proposes an integrated benchmarking framework illustrated in the context of a large supply chain system comprised of 102 distribution centers (DCs). We employ recent extensions of data envelopment analysis while addressing difficulties often associated with empirical data in real life settings. The study measures DC productivity in a large scale setting, evaluates and identifies DCs with consistent best performance using facet analysis, and detects performance trends using window analysis of 4 years’ data. This extensive evaluation of the empirical production frontier and of “role model” DCs provided very interesting insights for strategically managing operations. Our approach opens up possible new directions for examining supply chain DCs or other activities where explicit knowledge about the relationship between the inputs and outputs is not well known.
Determination of an optimal set of design requirements using house of quality
Authors: Park Taeho , Kim Kwang‐Jae
Published: July 2002

Quality Function Deployment (QFD) has been used to translate customer needs and wants into technical design requirements in order to increase customer satisfaction. QFD utilizes the house of quality (HOQ), which is a matrix providing a conceptual map for the design process, as a construct for understanding Customer Requirements (CRs) and establishing priorities of Design Requirements (DRs) to satisfy them. Some methodological issues occurring in the conventional HOQ are discussed, and then a new integrative decision model for selecting an optimal set of DRs is presented using a modified HOQ model. The modified HOQ prioritization procedure employs a multi‐attribute decision method for assigning relationship ratings between CRs and DRs instead of a conventional relationship rating scale, such as 1–3–9. The proposed decision model has been applied to an indoor air quality improvement problem as an illustrative example.
Nonlinear monotone semigroups and viscosity solutions
Authors: Biton Samuel
Published: July 2002

In a celebrated paper motivated by applications to image analysis, L. Alvarez, F. Guichard, P.-L. Lions and J.-M. Morel showed that any monotone semigroup defined on the space of bounded uniformly continuous functions, which satisfies suitable regularity and locality assumptions is in fact a semigroup associated to a fully nonlinear, possibly degenerate, second-order parabolic partial differential equation. In this paper, we extend this result by weakening the assumptions required on the semigroup to obtain such a result and also by treating the case where the semigroup is defined on a general space of continuous functions like, for example, a space of continuous functions with a prescribed growth at infinity. These extensions rely on a completely different proof using in a more central way the monotonicity of the semigroup and viscosity solutions methods. Then we study the consequences on the partial differential equation of various additional assumptions on the semigroup. Finally we briefly present the adaptation of our proof to the case of two-parameters families.

Dans un célèbre article motivé par les applications au traitement d’image, L. Alvarez, F. Guichard, P.-L. Lions and J.-M. Morel ont montré qu’un semi-groupe monotone défini sur l’espace des fonctions bornées uniformément continues satisfaisant des hypothèses de régularité et de localité est en fait un semi-groupe associé à une équation aux dérivées partielles parabolique non linéaire éventuellement dégénérée. Dans le présent article, nous étendons ce résultat en affaiblissant légèrement les hypothèses nécessaires et en traitant le cas de semi-groupes définis sur des espaces généraux de fonctions continues. Ces extension résultent d’une preuve totalement différente utilisant de manière plus centrale la monotonie du semi-groupe et des méthodes de solutions de viscosité. Nous étudions ensuite les conséquences d’hypothèses supplémentaires sur le semi-groupe. Finallement, nous présentons brièvement l’adaptation au cas d’une famille d’opérateurs à deux paramètres.
Quasiharmonic fields
Authors: Iwaniec Tadeusz , Sbordone Carlo
Published: July 2002

To every solution of an elliptic PDE there corresponds a quasiharmonic field

\mathcal F = [B,E]

− a pair of vector fields with

\mathrm{div} B = 0

and

\mathrm{curl} E=0

which are coupled by a distortion inequality. Quasiharmonic fields capture all the analytic spirit of quasiconformal mappings in the complex plane. Among the many desirable properties, we give dimension free and nearly optimal

L^p

-estimates for the gradient of the solutions to the divergence type elliptic PDEs with measurable coefficients. However, the core of the paper deals with quasiharmonic fields of unbounded distortion, which have far reaching applications to the non-uniformly elliptic PDEs. As far as we are aware this is the first time non-isotropic PDEs have been successfully treated. The right spaces for such equations are the Orlicz–Zygmund classes

L^2\log^αL

. Examples we give here indicate that one cannot go far beyond these classes.

A chaque solution d’une équation elliptique correspond un champ quasiharmonique

\mathcal F = [B,E]

, un couple de champs de vecteurs qui vérifient

\mathrm{div} B = 0

et

\mathrm{curl} E=0

et qui sont couplés par une inégalité de distorsion. Les champs harmoniques capturent l’esprit analytique des applications quasiconformes dans le plan complexe. Dans cet article sont fournies des estimations

L^p

concernant le gradient de solutions faibles d’une équation elliptique aux dérivées partielles, indépendantes de la dimension et presque optimales. Sont aussi considérés des champs quasiharmoniques avec distorsion non bornée, hypothèse non sans conséquences sur les équations non uniformément elliptiques. A notre connaissance c’est la première fois que sont obtenus des résultats significatifs pour des équations non-isotropiques. Les bons espaces pour de telles équations sont les espaces

L^2\log^αL

. Des exemples montrent qu’il est difficile de s’éloigner de cette classe.
Positive bound states having prescribed symmetry for a class of nonlinear elliptic equations in RN
Authors: Catrina Florin , Wang Zhi-Qiang
Published: July 2002

We consider positive solutions of

-\operatorname{div}(|x|^{-2a}\nabla u)=|x|^{-bp}u^{p-1},\quad u\geq 0\text{ in } \mathbf{R}^N

where for

N⩾2: a<(N−2)/2, a<b<a+1

, and

p=2N/(N−2(1+a−b))

. Ground state solutions are the extremal functions of the Caffarelli–Kohn–Nirenberg inequalities [6]. In [10] the authors have observed symmetry breaking phenomena for ground state solutions in a subregion of the parameters. In this paper, we continue our study on the structure of
bound state solutions
and construct bound state solutions having prescribed symmetry.

On considère les solutions positive à

-\operatorname{div}(|x|^{-2a}\nabla u)=|x|^{-bp}u^{p-1},\quad u\geq o\text{ dans } \mathbf{R}^N

où, pour

N⩾2: a<(N−2)/2, a<b<a+1

, et

p=2N/(N−2(1+a−b))

. Les solutions à état fondamental sont les fonctions extrémales pour les inégalités des Caffarelli–Kohn–Nirenberg [6]. Dans [10] les auteurs ont observé une brisure de symétrie pour les solutions d’état fondamental dans une région des paramètres. L’objet de cet article est l’étude de la structure des solutions à état borné et de construire des solutions à état borné avec une symétrie prescrite.
Long-time vanishing properties of solutions of some semilinear parabolic equations
Authors: Belaud Yves , Helffer Bernard , Véron Laurent
Published: July 2002

We study the long-time behavior of solutions of semilinear parabolic equations of the following type (PE)

∂_tu−∇.A(x,t,u,∇u)+f(x,u)=0

where

f(x,u)≈b(x)|u|^{q−1}u

,

b

being a nonnegative bounded and measurable function and

q

a real number such that

0≤q<1

. We give criteria which imply that any solution of the above equations vanishes in finite time and these criteria are associated to semi-classical limits of some Schrödinger operators. We also give a series of sufficient conditions on

b(x)

which imply that any supersolution with positive initial data does not to vanish identically for any positive

t

.

Nous étudions le comportement en temps grand de solutions d’équations paraboliques du type (PE)

∂_tu−∇.A(x,t,u,∇u)+f(x,u)=0

, où

f(x,u)≈b(x)|u|^{q−1}u

,

b

étant une fonction positive, bornée et mesurable, et

q

un nombre réel tel que

0≤q<1

. Nous donnons des critères qui impliquent que toute solution des équations ci-dessus devient identiquement nulle en temps fini et ces critères sont associés à des problèmes de limite semi-classique d’opérateurs de Schrödinger. Nous donnons aussi une série de conditions suffisantes sur

b(x)

qui impliquent que toute sur-solution avec des données initiales positives ne devient jamais identiquement égale à zéro.
A nonlinear oblique derivative boundary value problem for the heat equation: Analogy with the porous medium equation
Authors: Caffarelli Luis A , Roquejoffre Jean-Michel
Published: July 2002

The problem under investigation is the heat equation in the upper half-plane, to which the diffusion in the longitudinal direction has been suppressed, and augmented with a nonlinear oblique derivative condition. This paper proves global existence and qualitative properties to the Cauchy problem for this model, furthering the study [18] of the self-similar solutions. The qualitative behaviour of the solutions exhibits a strong analogy with the porous medium equation: propagation with compact support and finite speed, free boundary relation and time-asymptotic convergence to self-similar solutions.

Le problème étudié concerne l'équation de la chaleur dans le demi-plan supérieur, sans diffusion longitudinale, avec une condition à la limite non linéaire. On démontre l'existence globale d'une solution au problème de Cauchy, ainsi que diverses propriétés qualitatives. En particulier, les solutions présentent une forte analogie avec celles de l'équation des milieux poreux, comme : la propagation à vitesse finie, la relation de frontière libre et la convergence en temps grand vers des solutions auto-similaires.
Reaction-diffusion problems in cylinders with no invariance by translation. Part II: Monotone perturbations
Authors: Hamel François
Published: July 2002

The purpose of this work is the study of the existence and of
a priori
properties of solutions

(c, u)

of the following reaction-diffusion equations in infinite cylinders

Σ = ℝ × ω

with outward unit normal

\nu

:

\tag{P}
\begin{cases}
\Delta u - \beta \left(x_{1},y,c\right)\partial _{1}u + f\left(x_{1},u\right) = 0 & \text{in }\Sigma \\
\partial _{v}u = 0 & \text{on }\partial \Sigma \\
u\left( - \infty ,.\right) = 0,\ u\left( + \infty ,.\right) = 1 &
\end{cases}

The functions

−β

and

f

are given and are non decreasing in

x_1

. The results on the existence and on the necessary conditions are related to two “limit problems” as

x_1 → ±∞

.

Ce travail porte sur l’étude de l’existence et d’estimations
a priori
de solutions

(c, u)

d’équations de réaction-diffusion dans des cylindres infinis

Σ = ℝ × ω

de normale extérieure unitaire

\nu

:

\tag{P}
\begin{cases}
\Delta u - \beta \left(x_{1},y,c\right)\partial _{1}u + f\left(x_{1},u\right) = 0 & \text{dans }\Sigma \\ \partial _{v}u = 0 & \text{sur }\partial \Sigma \\
u\left( - \infty ,.\right) = 0,\ u\left( + \infty ,.\right) = 1 &
\end{cases}

Les fonctions

−β

et

f

sont données et sont croissantes par rapport à

x_1

. Les résultats d’existence et les conditions nécessaires sont reliés à deux « problèmes limites » quand

x_1 → ±∞

.
A generalization of the Weinstein-Moser theorems on periodic orbits of a Hamiltonian system near an equilibrium
Authors: Bartsch Thomas
Published: July 2002

We study the Hamiltonian system (HS)

\.{x} = JH′(x)

where

H \in C^2 (ℝ^{2N}, ℝ)

satisfies

H (0) = 0

,

H′ (0) = 0

and the quadratic form

Q(x) = \frac{1}{2}\langle H^{″}(0)x,x \rangle

is non-degenerate. We fix

τ_0 > 0

and assume that

ℝ^{2N} ≅ E\oplus F

decomposes into linear subspaces

E

and

F

which are invariant under the flow associated to the linearized system (LHS)

\.{x} = JH″ (0) x

and such that each solution of (LHS) in

E

is

τ_0

-periodic whereas no solution of (LHS) in

F − 0

is

τ_0

-periodic. We write

σ(τ_0) = σ_Q(τ_0)

for the signature of the quadratic form

Q

restricted to

E

. If

σ(τ_0) ≠ 0

then there exist periodic solutions of (HS) arbitrarily close to 0. More precisely we show, either there exists a sequence

x_k → 0

of

τ_k

-periodic orbits on the energy level

H^{−1} (0)

with

τ_k → τ_0

; or for each

λ

close to 0 with

λσ(τ_0) > 0

the energy level

H^{−1} (λ)

contains at least

½|σ(τ_0)|

distinct periodic orbits of (HS) near 0 with periods near

τ_0

. This generalizes a result of Weinstein and Moser who assumed

Q\mid E

to be positive definite.

Nous considérons le système hamiltonien (HS)

\.{x} = JH′(x)

ou

H \in C^2 (ℝ^{2N}, ℝ)

satisfait

H (0) = 0

,

H′ (0) = 0

et la forme quadratique

Q(x) = \frac{1}{2}\langle H^{″}(0)x,x \rangle

est non-dégénérée. Nous fixons

τ_0 > 0

et supposons

ℝ^{2N} ≅ E\oplus F

est la somme des sous-espaces linéaires

E

,

F

qui sont invariants sous le flot associé au système linéaire (LHS)

\.{x} = JH″ (0) x

. En plus chaque solution de (LHS) dans

E

est

τ_0

-périodique lorsqu’aucune des solutions de (LHS) dans

F − 0

soit

τ_0

-périodique. Soit

σ(τ_0) = σ_Q(τ_0)

la signature de la forme quadratique

Q

restreint à

E

. Si

σ(τ_0) ≠ 0

il existe des solutions périodiques de (HS) arbitrairement près de 0. Plus précisément nous démontrons que ou bien il existe une suite

x_k → 0

des solutions

τ_k

-périodique au niveau

H^{−1} (0)

avec

τ_k → τ_0

ou bien pour chaque

λ

près de 0 tel que

λσ(τ_0) > 0

il existe au moins

\frac{1}{2}\left|\sigma \left(\tau _{0}\right)\right|

solutions périodiques au niveau

H^{−1} (λ)

près de 0 avec des périodes près de

τ_0

. Ce résultat généralise un théorème de Weinstein et Moser qui supposent que

Q\mid E

est positif défini.
Reaction-diffusion problems in cylinders with no invariance by translation. Part I: Small perturbations
Authors: Hamel François
Published: July 2002

This paper deals with existence and uniqueness of solutions

(c,u)

of reaction-convection-diffusion equations mainly derived from combustion models and set in infinite cylinders

Σ = \{(x_1,y) ∈ ℝ × ω\}

\begin{cases}
a(x_1,y,u,\nabla u)\Delta u - (c + \alpha (y))\partial _1 u + \overrightarrow{q}(x_1,y,u,\nabla u) \cdot \nabla u \\
\qquad + f(u) + g(x_{1},y,u,\nabla u) = 0& \text{in }\Sigma \\
\partial _{\nu }u = 0 &\text{on }\partial \Sigma \\
u( - \infty , \cdot) = 0,\quad u( + \infty , \cdot ) = 1
\end{cases}

The functions

a

,

α

,

\overrightarrow q

,

f

and

g

are given. The section

ω

is a bounded smooth domain with outward unit normal

ν

. The existence of

(c,u)

is proved under various normalization conditions when the perturbative terms a,

\overrightarrow q

,

g

are close to

(1,\overrightarrow 0,0)

, and a continuity result as

(a,\overrightarrow q,g) → (1,\overrightarrow 0,0)

is stated.

Cet article traite de l’existence et de l’unicité de solutions

(c,u)

d’équations de réaction-convection-diffusion provenant essentiellement de modèles de combustion et posées dans des cylindres infinis

Σ = \{(x_1,y) ∈ ℝ × ω\}

\begin{cases}
a(x_1,y,u,\nabla u)\Delta u - (c + \alpha (y))\partial _1 u + \overrightarrow{q}(x_1,y,u,\nabla u) \cdot \nabla u \\
\qquad + f(u) + g(x_{1},y,u,\nabla u) = 0& \text{in }\Sigma \\
\partial _{\nu }u = 0 &\text{on }\partial \Sigma \\
u( - \infty , \cdot) = 0,\quad u( + \infty , \cdot ) = 1
\end{cases}

Les fonctions

a

,

α

,

\overrightarrow q

,

f

et

g

sont données. La section

ω

est un domaine borné régulier de normale extérieure unitaire

ν

. L’existence de

(c,u)

est prouvée pour différentes conditions de normalisation quand les termes perturbatifs a,

\overrightarrow q

,

g

sont proches de

(1,\overrightarrow 0,0)

, et on énonce un résultat de continuité quand

(a,\overrightarrow q,g) → (1,\overrightarrow 0,0)

.
Eventual monotonicity and convergence to travelling fronts for the solutions of parabolic equations in cylinders
Authors: Roquejoffre Jean-Michel
Published: July 2002

The paper is concerned with the long-time behaviour of the solutions of a certain class of semilinear parabolic equations in cylinders, which contains as a particular case the multidimensional thermo-diffusive model in combustion theory. We prove, under minimal conditions on the initial values, that the solutions eventually become monotone in the direction of the axis of the cylinder on every compact subset; this implies convergence to travelling fronts. This result is applied to propagation versus extinction problems: given a compactly supported initial datum, sufficient conditions ensuring that the solution will either converge to 0 or to a pair of travelling fronts are given. Additional information on the corresponding equations in finite cylinders is also obtained.

Cet article traite du comportement en grand temps des solutions d’une classe d’équations paraboliques dans des cylindres; ce type d’équation contient le modèle thermo-diffusif multidimensionnel de la théorie de la combustion. Nous montrons que, sous des hypothèses minimales sur la donnée initiale, les solutions deviennent, en temps fini, monotones sur tout compact dans la direction de l’axe du cylindre; ceci implique la convergence vers des ondes progressives. Ce résultat est ensuite appliquéà des problèmes de propagation et d’extinction: une donnée initiale étant fixée, on donne des conditions suffisantes pour que la solution qui en est issue tende vers 0, ou converge vers deux fronts se déplaçant dans des directions opposées. On obtient enfin des informations supplémentaires pour des équations dans des cylindres bornés.
Bifurcation and stability of families of hyperbolic vector fields in dimension three
Authors: Plaza Sergio , Vera Jaime
Published: July 2002

In this article we study the global stability of one-parameter families of hyperbolic vector fields with simple bifurcations in three-dimensional manifolds at least in all known cases (
see
introduction).

L’objet de ce travail est d’étudier la stabilité globale des familles à un paramètre de champs de vecteurs hyperboliques avec bifurcations simples dans les variétés de dimension trois. Cette étude est faite au moins dans les cas connus (voir le préliminaire).
Homoclinics: Poincaré-Melnikov type results via a variational approach
Authors: Ambrosetti Antonio , Badiale Marino
Published: July 2002

We introduce a variational approach to obtain some Poincaré-Melnikov type results on the existence and multiplicity of homoclinics.
Multiple boundary peak solutions for some singularly perturbed Neumann problems
Authors: Gui Changfeng , Wei Juncheng , Winter Matthias
Published: July 2002

We consider the problem

\begin{cases}
ɛ^{2}\Delta u - u + f\left(u\right) = 0 & \text{in }\Omega \\
u > 0 \text{ in }\Omega , \quad \partial \text{u}/ \partial v = 0 &\text{on }\partial \Omega ,
\end{cases}

where

Ω

is a bounded smooth domain in

R^N

,

ɛ > 0

is a small parameter and

f

is a superlinear, subcritical nonlinearity. It is known that this equation possesses boundary spike solutions such that the spike concentrates, as

ε

approaches zero, at a critical point of the mean curvature function

H(P)

,

P \in ∂ Ω

. It is also known that this equation has multiple boundary spike solutions at multiple nondegenerate critical points of

H(P)

or multiple local maximum points of

H(P)

.

In this paper, we prove that for any fixed positive integer

K

there exist boundary

K

-
peak
solutions at a local minimum point of

H(P)

. This implies that for any smooth and bounded domain there always exist boundary

K

-
peak
solutions.

We first use the Liapunov–Schmidt method to reduce the problem to finite dimensions. Then we use a maximizing procedure to obtain multiple boundary spikes.

Nous considerons le problème

\begin{cases}
ɛ^{2}\Delta u - u + f\left(u\right) = 0 & \text{in }\Omega \\
u > 0 \text{ in }\Omega , \quad \partial \text{u}/ \partial v = 0 &\text{on }\partial \Omega ,
\end{cases}

où Ω est une domaine bornée avec frontiére lisse en

R^N

,

ɛ > 0

est un parametre petit, et

f

est surlinéaire et souscritique. Il est bien connu que cette équation possede des solutions avec pointe sur la frontiére telle que la pointe se concentre (quand

ε

tend vers zero) à une pointe critique de la courbure moyenne

H(P) \in ∂ Ω

. Il est aussi connu que cette équation possede pleusieurs solutions avec pointes qui se concentrent sur pleusieurs points critiques nondégénerés de

H(P)

, ou sur pleusieurs maxima locaux de

H(P)

.

Dans ce papier, nous prouvons que, pour chaque entier positif

K

donné, il existe solutions avec

K

pointes l̀a frontiére, situées sur un minimum relatif de

H(P)

. Ceci implique que pour chaque domaine qui est lisse et bornée il existe toujours des solutions avec

K

pointes à la frontiére.

Nous utilisons la methode de Liapunov–Schmidt pour reduire le problème dans une espace de dimension finie. Ensuite, nous utilisons une procédé de maximization pour obtenir les pointes sur la frontiére.
Young measure approach to characterization of behaviour of integral functionals on weakly convergent sequences by means of their integrands
Authors: Sychev M.
Published: July 2002

It is known that sequential weak lower semicontinuity and weak-strong convergence (in the scalar case) properties of integral functionals may be characterized by means of their integrands. In this paper we introduce a Young measure approach obtaining both these results and the characterization for the second property in the vector-valued case. We discuss also motivations for the definition of strict quasiconvexity, and point out that the characterization of the classes of functionals having weak-strong convergence property everywhere is not a trivial problem in the general case.

On sait que les propriétés de semicontinuité séquentielle faible et de convergence faible-forte (dans le cas scalaire) pour les intégrales fonctionnelles peuvent être caractérisées au moyen de leurs intégrants. Dans ce papier nous introduisons une approche pour la mesure de Young et nous obtenons ces résultats ainsi que la caractérisation de la seconde propriété dans le cas à valeur vectorielle. Nous discutons également les motivations pour définir la quasiconvexité stricte, et remarquons que la caractérisation des classes de fonctionnelles ayant partout la propriété de convergence faible-forte n’est pas un problème trivial dans le cas général.
Multiple homoclinic solutions for a class of autonomous singular systems in R2
Authors: Caldiroli Paolo , Nolasco Margherita
Published: July 2002

We look for homoclinic solutions for a class of second order autonomous Hamiltonian systems in

\mathbf R^2

with a potential

V

having a strict global maximum at the origin and a finite set

S ⊂ \mathbf R^2

of singularities, namely

V(x) → −∞

as

\mathrm{dist}(x, S) → 0

. We prove that if

V

satisfies a suitable geometrical property then for any

k\in N

the system admits a homoclinic orbit turning

k

times around a singularity

ξ\in S

.

Nous cherchons des solutions homoclines pour une classe de systèmes hamiltoniens autonomes du second ordre dans

\mathbf R^2

définis par un potentiel

V

ayant un maximum global strict à l’origine et un ensemble fini

S ⊂ \mathbf R^2

de singularités:

V(x) → −∞

quand

\mathrm{dist}(x, S) → 0

. Nous montrons que si

V

vérifie une certaine propriété géométrique, alors le système possède une orbite homocline qui tourne

k

fois autour d’une singularité

ξ\in S

.
The structure of extremals of a class of second order variational problems
Authors: Marcus Moshe , Zaslavski Alexander J.
Published: July 2002

We study the structure of extremals of a class of second order variational problems without convexity, on intervals in

R_+

. The problems are related to a model in thermodynamics introduced in [7]. We are interested in properties of the extremals which are independent of the length of the interval, for all sufficiently large intervals. As in [12, 13] the study of these properties is based on the relation between the variational problem on bounded, large intervals and a limiting problem on

R_+

. Our investigation employs techniques developed in [10, 12, 13] along with turnpike techniques developed in [16, 17].

On étudie la structure des extrêmales d’une classe de problèmes variationnels non convexes du deuxième ordre, sur des intervalles de

R_+

. Ces problèmes sont reliés à un modèle thérmodynamique introduit dans [7]. Nous nous intéressons aux propriétés des extrêmales qui ne dependent pas de la longeur des intervalles, pourvu que ceux-ci soient assez grands. Comme dans [12,13] l’etude de ces propriétés s’appuie sur la relation entre le problème variationnel sur de grands intervalles bornés et un problème limite sur

R_+

. Notre travail emploie des techniques développées dans [10,12,13] ainsi que dans [16,17].
The effect of recombinant human bone morphogenetic protein‐2 on femoral reconstruction with an intercalary allograft in a dog model
Authors: Pluhar G. Elizabeth , Manley Paul A. , Heiner John P. , Vanderby Ray , Seeherman Howard J. , Markel Mark D.
Published: July 2002

This study compared the effect of augmentation of allograft–host bone junctions with recombinant human bone morphogenetic protein‐2 (rhBMP‐2) on an absorbable collagen sponge (ACS), autogenous cancellous bone graft (CBG), and a collagen sponge alone in a canine intercalary femoral defect model repaired with a frozen allograft. Outcome assessment included serial radiographs, dual energy X‐ray absorptiometry scans, and gait analyses, and mechanical testing and histology of post‐mortem specimens. The distal junction healed more quickly and completely with rhBMP‐2 than ACS alone based on qualitative radiography and histologic evaluations. The primary tissue in the unhealed gaps in the ACS group was fibrous connective tissue. The proximal allograft–host bone junction had complete bone union in the three treatment groups. There was significantly greater new bone callus formation at both junctions with rhBMP‐2 than with CBG or ACS alone that resulted in increased bone density around the allograft–host bone junctions. All dogs shifted their weight from the treated leg to the contralateral pelvic limb immediately after surgery. Weight bearing forces were redistributed equally between the pelvic limbs at 12 weeks after surgery with rhBMP‐2, at 16 weeks after surgery with CBG, and at 24 weeks after surgery with ACS alone. Bending and compressive stiffnesses of the whole treated femora were equal to the contralateral control femora in all treatment groups, whereas torsional rigidities of the whole treated femora for the CBG and ACS groups were significantly less than the control. Both the proximal and distal junctions the treated with rhBMP‐2 had torsional stiffnesses and strengths equal to intact control bones. Ultimate failure torques of the proximal junctions of the CBG group and of both junctions of the ACS group were significantly less than the BMP‐treated bones. Augmentation of the allograft–host bone junctions with rhBMP‐2 on an ACS gave results for all parameters measured that equaled or exceeded autogenous graft in this canine intercalary femoral defect model. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.