bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear lower bounds for δc(p) for a class of 2D self‐destructive percolation models
Authors: van den Berg J. , de Lima B.N.B.
Published: February 2009

The self‐destructive percolation model is defined as follows: Consider percolation with parameter p > pc. Remove the infinite occupied cluster. Finally, give each vertex (or, for bond percolation, each edge) that at this stage is vacant, an extra chance δ to become occupied. Let δc(p) be the minimal value of δ, needed to obtain an infinite occupied cluster in the final configuration. This model was introduced by van den Berg and Brouwer. They showed, for the site model on the square lattice (and a few other 2D lattices satisfying a special technical condition) that δc(p) ≥ ${(p-p_{c})\over {p}} $. In particular, δc(p) is at least linear in p − pc.

Although the arguments used by van den Berg and Brouwer look very lattice‐specific, we show that they can be suitably modified to obtain similar linear lower bounds for δc(p) (with p near pc) for a much larger class of 2D lattices, including bond percolation on the square and triangular lattices, and site percolation on the star lattice (or matching lattice) of the square lattice. © 2009 Wiley Periodicals, Inc. Random Struct. Alg., 2009
Cytochrome c on Silica Nanoparticles: Influence of Nanoparticle Size on Protein Structure, Stability, and Activity
Authors: Shang Wen , Nuffer Joseph H. , Muñiz‐Papandrea Virginia A. , Colón Wilfredo , Siegel Richard W. , Dordick Jonathan S.
Published: February 2009

The structure, thermodynamic and kinetic stability, and activity of cytochrome c (cyt c) on silica nanoparticles (SNPs) of different sizes have been studied. Adsorption of cyt c onto larger SNPs results in both greater disruption of the cyt c global structure and more significant changes of the local heme microenvironment than upon adsorption onto smaller SNPs. The disruption of the heme microenvironment leads to a more solvent‐accessible protein active site, as suggested by Soret circular dichroism spectroscopy and through an increase in peroxidase activity as a function of increased SNP size. Similarly, the stability of cyt c decreases more dramatically upon adsorption onto larger SNPs. These results are consistent with changes in protein–nanoparticle interactions that depend on the size or surface curvature of the supporting nanostructure. This study provides further fundamental insights into the effects of nanoscale surfaces on adsorbed protein structure and function.
Rational Synthesis of Magnetic Thermosensitive Microcontainers as Targeting Drug Carriers
Authors: Chen Li‐Bo , Zhang Feng , Wang Chang‐Chun
Published: February 2009

A new approach to the fabrication of magnetic thermosensitive microcontainers of Fe3O4 nanoparticles with poly(N‐isopropylacrylamide) walls is presented. The microcontainers undergo a temperature‐induced volume phase transition and present an impressive magnetic response. The microcontainers have a well‐defined structure with a narrow size distribution. The wall thicknesses of the microcontainers can be controlled according to requirements. Compared to other preparation methods, the process is simple and reproducible. The magnetic saturation of these microcontainers is high enough to meet most requirements of bioapplications. To further investigate the potential application of these microcontainers, they are tested as drug carriers, with the drug loading and releasing processes carefully studied. The drug encapsulation efficiency and drug content in the carriers are pH‐dependent, and the carriers have a maximal drug loading of about 50 wt% under alkaline conditions. The release of the drug from the microcontainers can be controlled by the environmental pH, temperature, and magnetic force.
Cobalt Nanoparticle Arrays made by Templated Solid‐State Dewetting
Authors: Oh Yong‐Jun , Ross Caroline A. , Jung Yeon Sik , Wang Yang , Thompson Carl V.
Published: February 2009

Self‐assembled cobalt particle arrays are formed by annealing, which cause agglomeration (dewetting) of thin Co films on oxidized silicon substrates that are topographically prepatterned with an array of 200‐nm‐period pits. The Co nanoparticle size and uniformity are related to the initial film thickness, annealing temperature, and template geometry. One particle per 200‐nm‐period pit is formed from a 15‐nm film annealed at 850 °C; on a smooth substrate, the same annealing process forms particles with an average interparticle distance of 200 nm. Laser annealing enables templated dewetting of 5‐nm‐thick films to give one particle per pit. Although the as‐deposited films exhibit a mixture of hexagonal close‐packed and face‐centered cubic (fcc) phases, the ordered cobalt particles are predominantly twinned fcc crystals with weak magnetic anisotropy. Templated dewetting is shown to provide a method for forming arrays of nanoparticles with well‐controlled sizes and positions.
A Simple Top‐Down/Bottom‐Up Approach to Sectored, Ordered Arrays of Nanoscopic Elements Using Block Copolymers
Authors: Park Soojin , Yavuzcetin Ozgur , Kim Bokyung , Tuominen Mark T. , Russell Thomas P.
Published: February 2009

A top‐down/bottom‐up approach is demonstrated by combining electron‐beam (e‐beam) lithography and a solvent annealing process. Micellar arrays of polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP) with a high degree of lateral order can be produced on a surface where sectoring is defined by e‐beam patterning. The e‐beam is used to crosslink the block copolymer (BCP) film immediately after spin‐coating when the BCP is disordered or in a highly ordered solvent‐annealed film. Any patterns can be written into the BCP by crosslinking. Upon exposure to a preferential solvent for the minor component block followed by drying, cylindrical nanopores are generated within the nonexposed areas by a surface reconstruction process, while, in the exposed areas, the films remain unchanged. Nickel nanodot arrays can be placed over selected areas on a surface by thermal evaporation and lift‐off process.
A method for enterprise knowledge map construction based on social classification
Authors: Liu Lu , Li Jing , Lv Chenggong
Published: February 2009

Knowledge map is an important and effective instrument for enterprise knowledge management. A large number of unordered knowledge resources in the enterprises bring about difficulties to the knowledge map construction. It is necessary to construct the enterprise knowledge map from a systematic perspective. Considering influences of individual's cognition on the organizational knowledge structure, this paper introduces social classification into the enterprise context and proposes a three‐level architecture for enterprise knowledge map construction, i.e. the individual knowledge tagging, the domain topic selection and the inter‐domain association analysis layer. In this architecture, domain serves as the basic unit to display knowledge and their relationships, as well as provides a pragmatic context for knowledge navigation and reuse. Incorporating the above elements, a method is formulated and applied to a real‐world case. Copyright © 2009 John Wiley & Sons, Ltd.
Analysing relational benefits in e‐business environment from behavioural perspective
Authors: Su Qin , Li Ling , Cui Yan Wu
Published: February 2009

This paper explores relational benefits from Chinese customer's behavioural perspective, which is a valuable addition to the existing literature that focuses on the western cultural background. The findings of this research show that the relational benefits exist in the online shopping context. In addition to confidence benefit, special treatment benefit and social benefit that have been recognized in traditional services, a new benefit scale, honour benefit, is identified in this study. Empirical data from over 500 online consumers suggest that the relational benefits are becoming more and more important and can possibly turn into the sources of the new competitive advantage for the enterprise in the e‐business environment. Copyright © 2009 John Wiley & Sons, Ltd.
A global approach for three‐dimensional analysis of tall buildings
Authors: Carpinteri A. , Lacidogna G. , Puzzi S.
Published: February 2009

In the literature, several approximate approaches have been proposed to analyse the lateral loading distribution of external loads in high‐rise buildings; in this paper, a general method is proposed for the analysis of the lateral loading distribution of three‐dimensional structures composed of any kind of bracings (frames, framed walls, shear walls, closed and/or open thin‐walled cores and tubes) under the customary assumption of floor slabs being undeformable in their planes. This general formulation allows analyses of high‐rise structures by taking into account the torsional rigidity of the elements composing the building without gross simplifications, even in the case of very complex shapes and with the contemporary presence of different kinds of bracing. The method is aimed at gaining an insight into the force flow in the structure, in order to understand how the building response is governed by decisive structural parameters and to compare preliminary calculations with other approaches such as the structural finite element analysis. Copyright © 2009 John Wiley & Sons, Ltd.
Reaktive Nanometer‐Multischichten als maßgeschneiderte Wärmequellen beim Fügen
Authors: Dietrich Georg , Braun Stefan , Gawlitza Peter , Leson Andreas
Published: February 2009

Zum Fügen von Bauteilen eingesetzte Löt und Schweißverfahren haben im Allgemeinen eine deutliche Erwärmung der an die Fügezonen angrenzenden Bereiche zur Folge. Dies kann zu festigkeitsmindernden Gefügeveränderungen der Materialien und/ oder zu Eigenspannungen aufgrund unterschiedlicher Wärmeausdehnung der zu fügenden Bauteile führen. Ein neuer Ansatz, die für das Fügen notwendige Energie kurzzeitig und exakt im Bereich der Fügezone einzubringen, wurde kürzlich durch die Entwicklung von sogenannten Reaktivmultischichten (RMS) eröffnet. RMS bestehen aus mehreren hundert bis zu einigen tausend Wechselschichten aus mindestens zwei Materialien, welche exotherm miteinander reagieren können. Die Dicken der Einzelschichten liegen dabei im Bereich von 10‐50 nm. Nach Einwirkung einer Aktivierungsenergie wird innerhalb der Nanometer‐Multischicht eine atomare Interdiffusion beider Materialien ineinander angeregt, wodurch es innerhalb kürzester Zeit zu einer hohen Wärmefreisetzung in einem lokal eng begrenzten Gebiet kommt. Durch Variation von Materialzusammensetzung, Periodendicke und Gesamtschichtdicke kann gezielt Einfluss auf charakteristische Eigenschaften der RMS wie abgegebene Wärmemengen, Ausbreitungsgeschwindigkeiten und maximal erreichbare Temperaturen genommen werden. Für die industrielle Anwendung steht damit eine präzise kontrollierbare und maßgeschneiderte Energie‐ bzw. Wärmequelle zur Verfügung.

Zur Herstellung der Reaktivmultischichten werden Sputterverfahren, wie das Magnetronsputtern und das Ionenstrahlsputtern angewandt. Mit diesen Verfahren können Nanometerschichten über einen langen Zeitraum reproduzierbar, hochpräzise und stabil abgeschieden werden. Die RMS werden dabei direkt auf die jeweiligen Bauteile beschichtet oder auch als universell einsetzbare freistehende Folie hergestellt.
HiPIMS ‐ Technologie und Anwendungsfelder
Authors: Bandorf Ralf , Vergöhl Michael , Werner Oliver , Sittinger Volker , Bräuer Günter
Published: February 2009

Seit der Einführung der planaren Magnetronkatode Mitte der siebziger Jahre hat die Magnetronzerstäubung fast alle Industriezweige, für die dünne Schichten eine Rolle spielen, im Sturm erobert. Zahlreiche Meilensteine wurden in den zurückliegenden 30 Jahren gesetzt. Zu den wichtigsten zählen sicher das Rohrmagnetron („CMAG”︁) und die Einführung gepulster Plasmen. Hochleistungs‐Impuls‐Magnetronsputtern (HiPIMS) oder auch Hochleistungs‐Puls‐Magnetronsputtern (HPPMS) ist ein weiterer innovativer Schritt zu Schichten mit neuer Qualität. HiPIMS nutzt Pulse im Megawattbereich, so dass an der Targetoberfläche Leistungsdichten von 1000 W/cm2 und mehr erzeugt werden (konventionell: 20 – 50 W/cm2).

besonderen Vorteile der neuen Technik liegen darin, dass mit 50 – 90 % ein sehr hoher Anteil der am Substrat kondensierenden Spezies ionisiert ist, so dass herausragende Schichteigenschaften wie hohe Dichte, extrem glatte Oberflächen oder hohe Brechzahlen für optische Schichten erwartet werden können.

en einer Einführung in das Thema hochionisierter Puls‐Plasmen wird das Potenzial dieser neuen Technologie an aktuellen Forschungsergebnissen im Bereich industrieller Entwicklung für verschiedene Branchen vorgestellt.
Biological tissue characterisation in narrow beam x‐ray scattering techniques
Authors: Tartari A. , De Felici M. , Gambaccini M. , Querzoli P. , Bonifazzi C. , Ferrero C. , Felici R.
Published: February 2009

High‐quality momentum distributions of the x‐ray scattering intensity are obtained from intact excited biological samples in a wide interval of the momentum transfer variable covering the SAXS (small‐angle x‐ray scattering) and the WAXS (wide‐angle x‐ray scattering) ranges. It is shown that especially in the case of soft tissues the SAXS integrated intensity largely prevails compared to the WAXS opening its possible exploitation in practical narrow beam diagnostic techniques. Moreover, it is demonstrated that, in the SAXS regime, brain tissue can be characterised in terms of amplitude variations of the myelin series period. Copyright © 2009 John Wiley & Sons, Ltd.
How to Treat Esophageal Perforations When Determinants and Predictors of Mortality Are Considered
Authors: Udelnow Andrej , Huber‐Lang Markus , Juchems Markus , Träger Karl , Henne‐Bruns Doris , Würl Peter
Published: February 2009

Background

Published lethality rates of esophageal perforation (EP) vary depending on patient‐ and disease‐related factors. This study was designed to evaluate how these factors impact death. Furthermore, we calculated the predictive accuracy of the Mortality Prediction Model (MPM II) and the Simplified Acute Physiology Score (SAPS II) for in‐hospital death. Conclusions about treatment decisions were drawn based on our data and analysis of recent literature.

Methods

Every patient who was treated for EP at our department from December 2001 to July 2008 is included in this study. Logistic regression analyses of various risk factors, such as etiology, time interval, size, comorbidities, localization, type of treatment, and preexisting pathologies of the esophagus on death, were performed.

Results

Of the 41 patients diagnosed with EP, nine died (21%). The most important risk factor concerning death was cirrhosis of the liver (0 vs. 89% mortality; odds ratio, 208; P < 0.001). Accuracy for lethality risk prediction was calculated with MPM II and SAPS II on admission, and afterward the characteristic increase that occurred was evaluated by using receiver operator characteristic curves. Optimal results were achieved by using a characteristic SAPS II increase (AUC 0.86; P: 0.009) after the patient was admitted to the intensive care unit.

Conclusions

Our study was the first to demonstrate that a rapid or continuous increase more than 40 of the daily SAPS II clearly indicates that a high risk of death is imminent. This should be used as a reevaluation factor when choosing a treatment strategy.
Postoperative Fatigue: A Review
Authors: Zargar‐Shoshtari Kamran , Hill Andrew G.
Published: February 2009

Background

Postoperative fatigue (POF) significantly impacts well‐being after major surgery. However, this topic has received little emphasis.

Methods

We conducted a comprehensive search on major databases with a focus on studies relevant to assessment and etiology of POF.

Results

POF has been measured by a number of different and inadequate instruments. It has a complicated etiology, with a number of biological and psychological factors implicated. However, the etiology of this condition has not been fully explained.

Conclusions

The role of local inflammation in the development of POF requires further research. Multimodal interventions should be conducted with a focus on addressing various factors that contribute to the development and progression of POF.
Lateral Subfascial Endoscopic Perforating Vein Surgery as Treatment for Lateral Perforating Vein Incompetence and Venous Ulceration
Authors: Wang Mao‐hua , Jin Xing , Zhang Shi‐yi , Wu Xue‐jun , Zhong Zhen‐yue , Wang Mo , Dong Dian‐ning , Yuan Hai
Published: February 2009

Background

The aim of this study was to evaluate the clinical results of lateral subfascial endoscopic perforating vein surgery (SEPS).

Methods

Our study was conducted from February 2002 to January 2007. Sixty‐three patients with lateral incompetent perforating veins (IPVs) and venous ulceration were allocated to two groups. Group 1 comprised 31 patients (33 limbs) who underwent only routine surgery (saphenofemoral or saphenopopliteal ligation, stripping, phlebectomies, endovascular laser treatment [EVLT], medial SEPS, and skin grafting). Group 2 comprised 32 patients (35 limbs) who underwent our routine surgery with the addition of lateral SEPS. Bidirectional ultrasonography was performed before the operation, and 6 weeks, 6 months, and 1 year after surgery. Clinical score and disability score were collected at the same time.

Results

Twenty‐nine (87.9%) of 33 limbs with active ulcers in group 1 healed, with recurrence in four (12.1%) limbs at follow‐up at 25.9 ± 10.0 months. All 35 limbs in group 2 healed, with recurrence in 0 (0.0%) limbs at follow‐up at 25.4 ± 10.1 months. Lateral SEPS could reduce the rate of recurrence of ulcers (Kaplan–Meier analysis). Patients in group 2 also showed improvement in clinical and disability scores, although they were not statistically significant differences (t test, p > 0.05). A significantly higher proportion of patients in group 1 had IPVs on the lateral aspect of the lower leg on ultrosonography imaging.

Conclusions

Lateral SEPS could contribute to ulcer healing and reduce ulcer recurrence. The addition of lateral SEPS to routine surgery did reduce the number of IPVs. Lateral SEPS may be safe and effective for lateral perforating vein incompetence and venous ulceration.
Cervical degenerative index: a new quantitative radiographic scoring system for cervical spondylosis with interobserver and intraobserver reliability testing
Authors: Ofiram Elisha , Garvey Timothy A. , Schwender James D. , Denis Francis , Perra Joseph H. , Transfeldt Ensor E. , Winter Robert B. , Wroblewski Jill M.
Published: February 2009

Background

The lack of a widely available scoring system for cervical degenerative spondylosis encouraged the authors to establish and validate a systematic quantitative radiographic index.

Materials and methods

This study included intraobserver and interobserver reliability testing among three reviewers with different years of experience. Each observer independently scored four cervical radiographs of 48 patients at separate intervals, and statistical analysis of the grading was performed.

Results

There was high intraobserver and interobserver reliability between the two experienced observers. There was fair reliability between the less experienced observer and the more experienced observers.

Conclusions

The cervical degenerative index appears to be a reliable and reproducible radiographic assessment of cervical spondylosis. The index will have direct applicability for longitudinal study of cervical spondylosis and may be clinically relevant as well.
Effects of attack of saprobic fungi on twig litter decomposition by endophytic fungi
Authors: Fukasawa Yu , Osono Takashi , Takeda Hiroshi
Published: February 2009

Endophytic fungi of healthy twig tissues act as dominant primary colonizers of twig litters and are exposed to the attacks of saprobic secondary colonizers. In the present study, we examined the effect of interspecific interactions on the decay rate of twigs in laboratory experiments using two endophytic ascomycetes (Phomopsis sp. and Xylaria sp.) and two saprobic basidiomycetes (Mycena polygramma and Phanerochaete filamentosa) on twigs of Japanese beech (Fagus crenata) as a model system. Both endophytes were defensive against two saprobes on 2% malt agar, and were not replaced by the saprobes in the twigs during the incubation period. However, inoculation of the saprobes reduced the mass loss of twig components (acid‐unhydrolyzable residue (AUR), holocellulose, soluble carbohydrate, and polyphenol). Especially when the twigs previously inoculated with Xylaria sp. or Phomopsis sp. were successively inoculated with M. polygramma the net weight of AUR increased, which was probably due to the synthesized melanin in hyphae of the endophytes. Our findings indicate that interspecific interactions between endophytic and saprobic fungi do affect the total mass of humic substances produced during the litter decay process.
Proteomic Study of Hepatic Nuclear Extracts in an Adaptive Acetaminophen Tolerance Model
Authors: Steele Pamela S. , Linder Mark W. , Valdes Roland , Franke Deanna D. H. , Jortani Saeed A.
Published: February 2009

Introduction

Variability in response to acetaminophen (APAP)-induced aseptic inflammation and tolerance to the impending hepatic damage has been described. To understand the mechanism of adaptive tolerance, we investigated the proteomic profiles of crude nuclear lysates in a mouse model. We hypothesized that pretreatment with low doses of APAP prior to a toxic dose results in differential protein expression.

Materials and Methods

Mice (BALB/C) were separated into three groups: the pretreated (PT) group received incremental doses of APAP while the last dose only (LD) and naïve groups were given saline vehicle. A toxic dose of APAP was administered on the seventh day to the PT and LD animals only and all groups were euthanized 3 h postdose. Total protein from crude hepatic nuclear lysates were applied to protein arrays and analyzed by immunoaffinity mass spectrometry.

Results and Discussion

Comparative data analyses of protein peaks revealed a protein that was significantly increased at m/z of 60,030 (p60) in the LD animals vs the other two groups. The closest match for the preliminary identification of the p60 protein based on a Swiss-Prot/TagIdent database search using the approximate isoelectric point and molecular weight information was Ccr4–Not complex subunit-2. This protein is a subunit of a multiprotein complex and serves as a transcriptional suppressor involved in controlling mRNA synthesis and degradation. Preliminary identification was also supported by Western blot analysis using anti-CNOT2 antibody.

Conclusion

Considering the APAP tolerance model, we conclude that toxicogenomic approaches such as nuclear profiling are useful tools in assessing differential expression of transcriptional factors involved in inflammatory response and adaptive tolerance to toxins.
Evaluation of quality of life related to nutritional status
Authors: Wanden-Berghe Carmina , Sanz-Valero Javier , Escribà-Agüir Vicenta , Castelló-Botia Isabel , Guardiola-Wanden-Berghe Rocio ,   for Red de Malnutrición en Iberoamérica – Ciencia y Tecnología para el Desarrollo (Red MeI – CYTED)
Published: February 2009

The way in which the quality of life related to health (HRQoL) is affected by the nutritional status of the patient is a subject of constant interest and permanent debate. The purpose of the present paper is to review those studies that relate HRQoL to nutritional status and examine the tools (questionnaires) that they use to investigate this relationship. A critical review of published studies was carried out via an investigation of the following databases: MEDLINE (via PubMed); EMBASE; The Cochrane Library; Cumulative Index to Nursing and Allied Health Literature (CINAHL); Institute for Scientific Information (ISI) Web of Science; Latin American and Caribbean Health Sciences Literature (LILACS); Spanish Health Sciences Bibliographic Index (IBECS). The search was carried out from the earliest date possible until July 2007.The medical subject heading terms used were ‘quality of life’, ‘nutritional status’ and ‘questionnaires’. The articles had to contain at least one questionnaire that evaluated quality of life. Twenty-eight documents fulfilling the inclusion criteria were accepted, although none of them used a specific questionnaire to evaluate HRQoL related to nutritional status. However, some of them used a combination of generic questionnaires with the intention of evaluating the same. Only three studies selectively addressed the relationship between nutritional status and quality of life, this evaluation being performed not by means of specific questionnaires but by statistical analysis of data obtained via validated questionnaires.
A cross-constrained variational problem for the generalized Davey–Stewartson system
Authors: Gan Zaihui , Zhang Jian
Published: February 2009

We study the sharp threshold for blow-up and global existence and the instability of standing wave eiωtuω(x) for the Davey–Stewartson system

in ℝ3, where uω is a ground state. By constructing a type of cross-constrained variational problem and establishing so-called cross-invariant manifolds of the evolution flow, we derive a sharp criterion for global existence and blow-up of the solutions to (DS), which can be used to show that there exist blow-up solutions of (DS) arbitrarily close to the standing waves.
Three-term arithmetic progressions and sumsets
Authors: Sanders Tom
Published: February 2009

Suppose that G is an abelian group and that A ⊂ G is finite and contains no non-trivial three-term arithmetic progressions. We show that |A+A| »ε|A|(log|A|)⅓−ε.
Multiplicity of positive solutions for a class of problems with critical growth in ℝN
Authors: Alves Claudianor O. , de Morais Filho Daniel C. , Souto Marco A. S.
Published: February 2009

Using variational methods, we establish the existence and multiplicity of positive solutions for the following class of problems:

where λ,β∈(0,∞), q∈(1,2*−1), 2*=2N/(N−2), N≥3, V,Z:ℝN→ℝ are continuous functions verifying some hypotheses.
On the characteristic initial-value problem for linear partial functional-differential equations of hyperbolic type
Authors: Šremr Jiří
Published: February 2009

Theorems on the Fredholm alternative and well-posedness of the characteristic initial-value problem

are established, where l : C($\mathcal{D}$;ℝ) is a linear bounded operator, q ∈ L($\mathcal{D}$;ℝ), ϕ:[a,b]→ℝ, ψ:[c,d]→ℝ are absolutely continuous functions and $\mathcal{D}$=[a,b]×[c,d]. Some solvability conditions of the problem considered are also given.
Multiplicity theorems for semilinear elliptic problems depending on a parameter
Authors: Kristály Alexandru , Papageorgiou Nikolaos S.
Published: February 2009

We consider semilinear elliptic problems in which the right-hand-side nonlinearity depends on a parameter λ > 0. Two multiplicity results are presented, guaranteeing the existence of at least three non-trivial solutions for this kind of problem, when the parameter λ belongs to an interval (0,λ*). Our approach is based on variational techniques, truncation methods and critical groups. The first result incorporates as a special case problems with concave–convex nonlinearities, while the second one involves concave nonlinearities perturbed by an asymptotically linear nonlinearity at infinity.
On application of kinetic formulation of the Le Roux system
Authors: Cheng Zhixin
Published: February 2009

We use the compensated compactness method coupled with some basic ideas of kinetic formulation developed by Lions, Perthame, Souganidis and Tadmor to give a refined proof for the existence of global bounded entropy solutions to the Le Roux system. This new method of the reduction of Young measures can be applied to solve other problems.
Geochemical stages at Jasper Seamount and the origin of intraplate volcanoes
Authors: Konter J. G. , Staudigel H. , Blichert‐Toft J. , Hanan B. B. , Polvé M. , Davies G. R. , Shimizu N. , Schiffman P.
Published: February 2009

Ocean intraplate volcanoes (OIVs) are formed in a sequence of stages, from large to small, that involve a systematic progression in mantle melting in terms of volumes and melt fractions with concomitant distinct mantle source signatures. The Hawaiian volcanoes are the best‐known example of this type of evolution, even though they are extraordinarily large. We explore the Pb‐Sr‐Nd‐Hf isotopic evolution of much smaller OIVs in the Fieberling‐Guadalupe Seamount Trail (FGST) and small, near‐ridge generated seamounts in the same region. In particular, we investigate whether we can extend the Hawaiian models to Jasper Seamount in the FGST, which displays three distinct volcanic stages. Each stage has characteristic variations in Pb‐Sr‐Nd‐Hf isotopic composition and trace element enrichment that are remarkably similar to the systematics observed in Hawaii: (1) The most voluminous, basal “shield building” stage, the Flank Transitional Series (FTS), displays slightly isotopically enriched compositions compared to the common component C and the least enriched trace elements (143Nd/144Nd: 0.512866–0.512909, 206Pb/204Pb: 18.904–19.054; La/Sm: 3.71–4.82). (2) The younger and substantially less voluminous Flank Alkalic Series (FAS) is comparatively depleted in Sr, Nd, and Hf isotope compositions plotting on the side of C, near the least extreme values for the Austral Islands and St. Helena. Trace elements are highly enriched (143Nd/144Nd: 0.512912–0.512948, 206Pb/204Pb: 19.959–20.185; La/Sm: 9.24). (3) The Summit Alkalic Series (SAS) displays the most depleted Sr, Nd, and Hf isotope ratios and is very close in isotopic composition to the nearby near‐ridge seamounts but with highly enriched trace elements (143Nd/144Nd: 0.512999–0.513050, 206Pb/204Pb: 19.080–19.237; La/Sm: 5.73–8.61). These data fit well with proposed multicomponent melting models for Hawaii, where source lithology controls melt productivity. We examine the effect of melting a source with dry peridotite, wet peridotite, and pyroxenite, calculating melt productivity functions with depth to evaluate the effect of potential temperature and lithospheric thickness. This type of melting model appears to explain the isotopic variation in a range of small to large OIVs, in particular for OIVs occurring far from the complicating effects of plate boundaries and continental crust, constraining their geodynamic origin.
Volcanic inflation measured in the caldera of Axial Seamount: Implications for magma supply and future eruptions
Authors: Nooner Scott L. , Chadwick William W.
Published: February 2009

Since 2000, ambient seawater pressure has been precisely measured at five seafloor benchmarks inside the summit caldera at Axial Seamount to monitor volcanic inflation, using a remotely operated vehicle to deploy a mobile pressure recorder (MPR) in campaign‐style surveys. Additionally, seawater pressure has been measured at the caldera center with multiyear deployments of continuously recording bottom pressure recorders (BPRs). These pressure data (converted to depth) are currently the only measurements of volcanic inflation at a submarine volcano. We show new data spanning 2004 to 2007 documenting steady inflation of 12.7 ± 0.4 cm/a at the caldera center. The spatial pattern of uplift is consistent with magma storage in a shallow reservoir underlying the caldera at a depth of ∼3.5 km, and the current uplift rate implies that magma is being supplied to the volcano at a rate of ∼7.5 × 106 m3/a. However, the supply rate immediately after the last eruption in 1998 was significantly higher, and the temporal pattern of uplift at Axial caldera appears to be governed by at least two processes occurring at very different time scales. We interpret the high uplift rates immediately following the 1998 eruption as either due to influx from one or more small satellite magma bodies or as the result of viscoelastic relaxation and/or poroelastic behavior of the crust surrounding the shallow magma chamber, and we present a numerical model which supports the latter interpretation. In contrast, we interpret the current lower uplift rate as due to a steady longterm magma supply from the mantle. This two component uplift pattern has not been observed on land volcanoes, suggesting that magma supply/storage processes beneath this ridge axis volcano differ from volcanoes on land (including Iceland). To reconstruct the uplift history at Axial, we fit the combined MPR and BPR data to two possible uplift scenarios, with which we forecast that the next eruption at Axial is likely to occur by about 2020, when most of the ∼3 m of deflation that occurred during the 1998 eruption will have been recovered.
Electron impact excitation of carbon monoxide in comet Hale‐Bopp
Authors: Campbell L. , Brunger M. J.
Published: February 2009

The fourth positive emissions of carbon monoxide in the coma of comet Hale‐Bopp have been assumed to be due mainly to fluorescence induced by sunlight. Based on this assumption they were used to deduce the abundance of carbon monoxide in the comet, giving a value higher than in other comets. Emissions produced by electron impact excitation of CO were not considered. Recent measurements and theoretical calculations of integral cross sections for electron impact excitation of CO allow the contribution of electron impact to be calculated, giving about 40% of the total. This implies that the abundance of CO in the outer coma of comet Hale‐Bopp was only 60% of that previously deduced. However, as the high proportion of CO in comet Hale‐Bopp was also seen in some other measurements, alternative explanations are considered. The method of calculation is tested by successfully predicting the O I emission at 1356 Å, supporting the belief that this line is due to electron impact excitation.
Cold dense magnetopause boundary layer under northward IMF: Results from THEMIS and MHD simulations
Authors: Li Wenhui , Raeder Joachim , Øieroset Marit , Phan Tai D.
Published: February 2009

A layer of nearly stagnant cold dense plasma is observed by THEMIS spacecraft in a closed field region immediately inside the dayside magnetopause near the low‐latitude boundary layer on 3 June 2007. Using the OpenGGCM global MHD magnetosphere numerical model, we successfully reproduce this observed cold dense plasma layer in the simulation. The simulation results show that reconnection first occurs poleward of the cusp in the northern hemisphere, creating new open field lines extending southward and forming an open field layer; then subsequently occurs in the other hemisphere, creating new closed field lines that capture the magnetosheath plasma and form the dayside cold dense plasma layer. In this event, the open layer and the skin of the cold dense plasma layer have a southward tangential flow while the inner part of the cold dense plasma layer has a more stagnant and more turbulent flow.
Evaluation of whistler‐mode chorus intensification on the nightside during an injection event observed on the THEMIS spacecraft
Authors: Li W. , Thorne R. M. , Angelopoulos V. , Bonnell J. W. , McFadden J. P. , Carlson C. W. , LeContel O. , Roux A. , Glassmeier K. H. , Auster H. U.
Published: February 2009

The intensification of the nightside whistler‐mode chorus emissions is observed in the low‐density region outside the plasmapause during the injection of anisotropic plasma sheet electrons into the inner magnetosphere. Time History of Events and Macroscale Interactions During Substorms data of the electron phase space density over the energy range between 0.1 keV and 30 keV are used to develop an analytical model for the distribution of injected suprathermal electrons. The path‐integrated gain of chorus waves is then evaluated with the HOTRAY code by tracing whistler‐mode chorus waves in a hot magnetized plasma. The simulated wave gain is compared to the observed wave electric field and magnetic field, respectively. The results indicate that lower‐energy (<1 keV) plasma sheet electrons can penetrate deeper toward the Earth but cause little chorus intensification, while higher‐energy (1 keV to tens of kiloelectron volts) electrons can be injected at relatively higher L‐shells and are responsible for the intensification of lower‐band and upper‐band whistler‐mode chorus. Compared to the lower‐band chorus, a relatively higher electron anisotropy is required to generate upper‐band chorus. In addition, higher plasma density results in stronger wave intensity and a broader frequency band of chorus waves.
Alfvén wave evolution within corotating interaction regions associated with the formation of magnetic holes/decreases
Authors: Tsubouchi K.
Published: February 2009

One‐dimensional magnetohydrodynamics (MHD) simulations were performed to validate the evolution of large‐amplitude Alfvénic fluctuations embedded in the high‐speed solar wind as it interacts with the low‐speed stream flowing ahead. It is well known that the interaction of the high‐ and low‐speed streams results in the formation of a corotating interaction region (CIR) bounded by forward and reverse shocks. After passing through the reverse shock, the initial Alfvénic fluctuation disintegrates into two Alfvén modes traveling in opposite directions in a plasma rest frame. These modes bound a region where the magnetic field intensity is largely below the background level. The appearance of this magnetic depression, called a “magnetic hole” (MH) or “magnetic decrease” (MD), is highly consistent with previous solar wind observations in that the structure is often identified close to the reverse shock within CIRs and holds pressure balance. The process by which such evolution of Alfvénic fluctuations results in MH/MD formation is elucidated: A local maximum in the field components of the fluctuation, which have originally monotonic gradients (e.g., dBy/dx < 0), is formed due to the amplification when the field passes through the reverse shock. This causes local current reversal (dBy/dx > 0) within the fluctuation, where the initial force balance (∇p ∼ J × B) is violated. The resultant force sweeps the plasma backward to form a pressure increase and simultaneous magnetic decrease within the CIR, which can be associated with a MH/MD. This model naturally describes the formation process of a MH/MD.
Wideband impedance matrix representation of passive waveguide components based on cascaded planar junctions
Authors: Mira F. , San Blas A. A. , Boria V. E. , Gimeno B.
Published: February 2009

A very efficient technique for the full‐wave analysis of passive waveguide components, composed of the cascade connection of planar junctions, is presented. This novel technique provides the wideband generalized impedance matrix representation of the whole structure in the form of pole expansions, thus extracting the most expensive computations from the frequency loop. For this purpose, the structure is segmented into planar junctions and uniform waveguide sections, which are characterized in terms of wideband impedance matrices. Then, an efficient iterative algorithm for combining such matrices, and finally providing the wideband generalized impedance matrix of the complete structure, is followed. Two waveguide filters have been used to prove the accuracy and efficiency of this novel technique, which is specially suited for modeling complex geometries.
Ionospheric penetration characteristics of ELF waves radiated from a current source in the lithosphere related to seismic activity
Authors: Ozaki M. , Yagitani S. , Nagano I. , Miyamura K.
Published: February 2009

Electromagnetic wave radiation from an underground current source related to seismic activity is discussed. In order to estimate the ionospheric effects on the electromagnetic waves associated with the seismic activity, ELF waves in the frequency range from 10 Hz to 1 kHz in the ionosphere radiated from a possible seismic current source modeled as an electric dipole located in the lithosphere, are precisely computed by using a full‐wave analysis. In this calculation, the ionosphere is assumed to be an inhomogeneous and anisotropic medium, and the Earth's crust is assumed to be a homogeneous and isotropic conductive medium. Especially, the effects of the geomagnetic field on the ionospheric wave propagation are precisely considered. The results of the calculations in the frequency range from 10 Hz to 1 kHz show frequency dependence in spatial distributions of the wave intensities due to the geomagnetic field‐aligned whistler propagation in the ionosphere and the Earth‐ionosphere waveguide propagation. Wave intensities which could be observed on the ground and in the ionosphere are determined by assuming the magnitude of the current moment of a seismic dipole source. In a possible situation, the current moment is estimated to be about 80 A·m/Hz1/2 which generates a detectable wave magnetic field on the ground just above a seismic source. However, if we try to detect it in the ionosphere, the source current moment must be thousands of times more intense.
Structure of human insulin-like peptide 5 and characterization of conserved hydrogen bonds and electrostatic interactions within the relaxin framework
Authors: Haugaard-Jönsson Linda M. , Hossain Mohammed Akhter , Daly Norelle L. , Craik David J. , Wade John D. , Rosengren K. Johan
Published: February 2009

INSL5 (insulin-like peptide 5) is a two-chain peptide hormone related to insulin and relaxin. It was recently discovered through searches of expressed sequence tag databases and, although the full biological significance of INSL5 is still being elucidated, high expression in peripheral tissues such as the colon, as well as in the brain and hypothalamus, suggests roles in gut contractility and neuroendocrine signalling. INSL5 activates the relaxin family peptide receptor 4 with high potency and appears to be the endogenous ligand for this receptor, on the basis of overlapping expression profiles and their apparent co-evolution. In the present study, we have used solution-state NMR to characterize the three-dimensional structure of synthetic human INSL5. The structure reveals an insulin/relaxin-like fold with three helical segments that are braced by three disulfide bonds and enclose a hydrophobic core. Furthermore, we characterized in detail the hydrogen-bond network and electrostatic interactions between charged groups in INSL5 by NMR-monitored temperature and pH titrations and undertook a comprehensive structural comparison with other members of the relaxin family, thus identifying the conserved structural features of the relaxin fold. The B-chain helix, which is the primary receptor-binding site of the relaxins, is longer in INSL5 than in its close relative relaxin-3. As this feature results in a different positioning of the receptor-activation domain ArgB23 and TrpB24, it may be an important contributor to the difference in biological activity observed for these two peptides. Overall, the structural studies provide mechanistic insights into the receptor selectivity of this important family of hormones.
Cellular and molecular effects of mechanical stretch on vascular cells and cardiac myocytes
Authors: Shyu Kou-Gi
Published: February 2009

Cells in the cardiovascular system are permanently subjected to mechanical forces due to the pulsatile nature of blood flow and shear stress, created by the beating heart. These haemodynamic forces play an important role in the regulation of vascular development, remodelling, wound healing and atherosclerotic lesion formation. Mechanical stretch can modulate several different cellular functions in VSMCs (vascular smooth muscle cells). These functions include, but are not limited to, cell alignment and differentiation, migration, survival or apoptosis, vascular remodelling, and autocrine and paracrine functions. Laminar shear stress exerts anti-apoptotic, anti-atherosclerotic and antithrombotic effects on ECs (endothelial cells). Mechanical stretch of cardiac myocytes can modulate growth, apoptosis, electric remodelling, alterations in gene expression, and autocrine and paracrine effects. The aim of the present review is primarily to summarize the cellular and molecular effects of mechanical stretch on vascular cells and cardiac myocytes, emphasizing the molecular mechanisms underlying the regulation. Knowledge of the impact of mechanical stretch on the cardiovascular system is vital to the understanding of the pathogenesis of cardiovascular diseases, and is also crucial to provide new insights into the prevention and therapy of cardiovascular diseases.
The protective effects of exercise and phosphoinositide 3-kinase (p110α) in the failing heart
Authors: Owen Kate L. , Pretorius Lynette , McMullen Julie R.
Published: February 2009

Despite the development of a wide range of therapies, heart failure remains a leading cause of death in Western society. New therapies are needed to help combat this debilitating condition. Exercise is becoming an increasingly important feature of rehabilitation programmes for patients with heart failure. Before the 1980s, patients with heart failure were advised not to exercise as it was thought that exercise would increase the risk of a cardiac event (such as myocardial infarction). However, in recent years both aerobic and resistance training have been shown to be safe and beneficial for patients with heart failure, improving exercise tolerance and quality of life, and preventing muscular deconditioning. The molecular mechanisms responsible for exercise-induced cardioprotection are yet to be elucidated, however studies in transgenic mice have identified PI3K(p110α) (phosphoinositide 3-kinase p110α) as a likely mediator. PI3K(p110α) is a lipid kinase which is activated in the heart during chronic exercise training, and is important for maintaining heart structure and function in various pathological settings. In the present review the protective effects of PI3K(p110α) in the failing heart and its potential as a therapeutic strategy for the treatment of heart failure is discussed.
RGS proteins: identifying new GAPs in the understanding of blood pressure regulation and cardiovascular function
Authors: Gu Steven , Cifelli Carlo , Wang Sean , Heximer Scott P.
Published: February 2009

Understanding the mechanisms that underlie BP (blood pressure) variation in humans and animal models may provide important clues for reducing the burden of uncontrolled hypertension in industrialized societies. High BP is often associated with increased signalling via G-protein-coupled receptors. Three members of the RGS (regulator of G-protein signalling) superfamily RGS2, RGS4 and RGS5 have been implicated in the attenuation of G-protein signalling pathways in vascular and cardiac myocytes, as well as cells of the kidney and autonomic nervous system. In the present review, we discuss the current state of knowledge regarding their differential expression and function in cardiovascular tissues, and the likelihood that one or more of these alleles are candidate hypertension genes. Together, findings from the studies described herein suggest that development of methods to modulate the expression and function of RGS proteins may be a possible strategy for the treatment and prevention of hypertension and cardiovascular disease.