bluuebunny/crossref_metadata_2025 huggingface dataset:
NONLOCAL OPTICAL PROPAGATION IN NONLINEAR NEMATIC LIQUID CRYSTALS
Authors: PECCIANTI MARCO , CONTI CLAUDIO , ASSANTO GAETANO , DE LUCA ANTONIO , UMETON CESARE
Published: January 2004

Optical propagation in nematic liquid crystals is characterized by a large and highly-nonlocal Kerr-like nonlinearity. We investigate the fundamental role played by spatial nonlocality in nonlinear optical propagation, and develop a model able to predict the main features of spatial solitons and modulational instability in nematic liquid crystals. The model unifies solitons in physical systems exhibiting different degrees of nonlocality, disclosing a connection between nonlocal solitons and parametric solitons in quadratic media. Finally, soliton breathing as well as other characteristics of nonlocal propagation are experimentally demonstrated in a specifically-engineered liquid crystal cell.
HIGHLY EFFICIENT HOLOGRAPHIC MATERIALS BASED ON POLYMER LIQUID CRYSTALS
Authors: OKANO KUNIHIKO , SHISHIDO ATSUSHI , TSUTSUMI OSAMU , SHIONO TAKESHI , IKEDA TOMIKI
Published: January 2004

Formation of gratings by means of the photoinduced alignment change of polymer liquid crystals (PLCs) has been explored in a glassy state. To obtain high diffraction efficiency (η), we synthesized highly birefringent PLCs containing an azobenzene group directly connected with a tolane moiety (3ATm), in which the alkyl spacer length ( CH 2)m was varied as m=6, 9 and 12. It was found that the values of birefringence in all the PLCs were about 0.4. The behaviors of the photoinduced alignment change and the formation of gratings were found to be dependent on the alkyl spacer length of 3ATm.
STRUCTURED, PHOTOSENSITIVE PVK AND PVCN POLYMER LAYERS FOR CONTROL OF LIQUID CRYSTAL ALIGNMENT
Authors: KACZMAREK MALGOSIA , DYADYUSHA ANDRIY
Published: January 2004

We present characteristics of liquid crystal reorientation in cells with alignment layers made of different poly(vinyl)-type polymers. Mechanically-rubbed poly(N-vinyl carbazole) (PVK) produces planar alignment of liquid crystals with easy axis orthogonal to the rubbing direction and zero pretilt angle. Doping PVK with C 60 makes this liquid crystal–polymer system extremely photosensitive for visible wavelengths. Illumination with a Gaussian beam reveals a complex structure of patterns of reoriented liquid crystal molecules. Using poly(vinyl-cinnamate) (PVCN), exposed to UV light, a periodic alignment of liquid crystals can be achieved via this all-optical method.
WIDELY-TUNABLE, MONOCHROMATIC, AND HIGH-POWER TERAHERTZ SOURCES AND THEIR APPLICATIONS
Authors: DING YUJIE J. , SHI WEI
Published: January 2004

We have demonstrated that coherent terahertz (THz) waves can be efficiently generated and tuned in extremely-wide ranges based on phase-matched difference-frequency generation (DFG) in second-order nonlinear materials. Among all the nonlinear crystals available, we have chosen GaSe and ZnGeP 2, which correspond to two of the best nonlinear materials for the efficient THz generation. This is due to the fact that these two materials have the lowest and next-to-lowest absorption coefficients in the THz domain. In addition, they possess large nonlinear coefficients. For a single GaSe crystal, continuously-tunable and coherent radiation in the extremely-wide ranges of 2.7–38.4 μ m and 58.2–3540 μ m has been achieved. Hence, a novel and promising THz source is finally available. This source has the additional advantages of high coherence (narrow linewidth) and simple alignment. The peak output power for the THz radiation reaches 209 W at the wavelength of 196 μ m (1.53 THz), which corresponds to a power conversion efficiency of 0.055%. On the other hand, for a single ZnGeP 2 crystal we have efficiently generated a monochromatic THz wave continuously-tunable in the ranges of 83.1–1642 μ m and 80.2–1416 μ m . The highest output peak power achieved so far is 134 W. We have also investigated how to use THz waveguides and long coherence lengths for improving the conversion efficiencies. We have reviewed our results on some important applications using these unique sources.
ACTIVE PHOTONIC CRYSTAL NANO-ARCHITECTURES
Authors: SUMMERS CHRISTOPHER J. , NEFF CURTIS W. , PARK WOUNJHANG
Published: January 2004

The development of nano-scaled photonic crystal structures has resulted in many new devices exhibiting non-classical optical behavior. Typically, in these structures a photonic band gap and associated defect mode are used to create waveguides, resonators, couplers and filters. In this paper we propose that the functionality of these structures can be significantly enhanced by the infiltration of the photonic crystal with other classes of materials, particularly highly nonlinear liquid crystals and electro-optical materials. The properties of conventional 2D PC slab waveguides were simulated by the finite difference time domain method and shown to exhibit very large refraction and dispersion, and significant tunable effects under bias when infiltrated with liquid crystal. In particular, a new superlattice photonic crystal concept is proposed and shown to exhibit up to ~50° tunability in the angle of refraction when alternate liquid crystal infiltrated pixel rows were modulated from their aligned to unaligned state. This modulation corresponds to index changes from 1.5 to 2.1; it is assumed that a refractive index change of up to approximately Δn=0.6 can be achieved. The superlattice effect was also demonstrated to induce new switching and out-coupling effects that were strongly dependent on the direction of propagation and index modulation. These simulations demonstrate the potential of a new class of optically-active photonic crystal architectures to tune giant refraction and dispersion characteristics and to enable new switching phenomena.
Island Shangri-La's Environmental Management System: A Long Way to Go!
Authors: Tsai Terence , Chan Larry Chi Chuen , Chou Kitty Hsin Yi , Schultz Maiken , Heike Ferdinandt , Yeung Ken Yuk-Lam
Published: December 2003

The Shangri-La Group was known throughout the world as a high-quality service provider in the hotel industry. This case focuses on the Island Shangri-La hotel's long and difficult process of attaining ISO 14001 certification. This involved challenging and changing the dominant "non-Green" business mindset and instilling a somewhat foreign environmentally friendly mentality in stakeholders. How to balance financial profitability with "greening" demands became central to sustaining the hotel's leadership position in an increasingly competitive market place.
BOL China
Authors: Fernandez Juan Antonio , Wang Jennifer Z. , Chen Dongjun
Published: December 2003

BOL China was part of the German group Bertelsmann, one of the biggest media groups in the world. The company was the pioneer of e-business in China with the establishment of Bertelsmann on Line (BOL China). The case presents the situation of the company after one year of operations and relates the difficulties of starting an e-business when the infrastructure of the country was limited. It describes the characteristics of e-business and the demands it posed in terms of strategy and operations. Finally, the case also explores the design of a performance measurement system for the e-business, using the Balanced Score-card as a model.
Gentran Machinery, Inc. (B)
Authors: Carl Pegels C.
Published: December 2003

The two cases describe the problems associated with the implementation of an international manufacturing joint venture in China between an American construction machinery firm and its Chinese counterpart. Case (A) presents the major hurdles the partners had to deal with: cultural, language and management problems. The conflicts between the two sides were exasperated by the lack of Western exposure to Chinese managers and the strict hierarchical management system in the Chinese side of the joint venture. Case (A) does not propose solutions but certainly raises many issues that need resolution.

Case (B) proposes solutions to the problems extensively described in the "A" case. General recommendations were proposed to address the following issues: (a) the general manager's position, power and authority in the joint venture, (b) the organizational design of the joint venture, (c) clarification of the responsibility of both parties, (d) reward system and appraisal system, (e) how to deal with both the Chinese and American incompetent managers, (f) how to deal with the communication problems, both language and cultural, and (g) final comprehensive and position outline of the potential of the joint venture.
STABILITY AND SIMULATION-BASED DESIGN OF STEEL SCAFFOLDING WITHOUT USING THE EFFECTIVE LENGTH METHOD
Authors: CHAN S. L. , CHU A. Y. T. , ALBERMANI F. G.
Published: December 2003

A robust computer procedure for the reliable design of scaffolding systems is proposed. The design of scaffolding is not detailed in design codes and considered by many researchers and engineers as intractable. The proposed method is based on the classical stability function, which performs excellently in highly nonlinear problems. The method is employed to predict the ultimate design load capacities of four tested 3-storey steel scaffolding units, and for the design of a 30 m×20 m×1.3 m 3-dimensional scaffolding system. As the approach is based on the rigorous second-order analysis allowing for the P-δ and P-Δ effects and for notional disturbance forces, no assumption of effective length is required. It is superior to the conventional second-order analysis of plotting only the bending moment diagram with allowance for P-Δ effect since it considers both P-Δ and P-δ effects such that section capacity check is adequate for strength and stability checking. The proposed method can be applied to large deflection and stability analysis and design of practical scaffolding systems in place of the conventional and unreliable effective length method which carries the disadvantages of uncertain assumption of effective length factor (Le/L).
NONLINEAR GENERALIZED BEAM THEORY FOR COLD-FORMED STEEL MEMBERS
Authors: SILVESTRE N. , CAMOTIM D.
Published: December 2003

A geometrically nonlinear Generalized Beam Theory (GBT) is formulated and its application leads to a system of equilibrium equations which are valid in the large deformation range but still retain and take advantage of the unique GBT mode decomposition feature. The proposed GBT formulation, for the elastic post-buckling analysis of isotropic thin-walled members, is able to handle various types of loading and arbitrary initial geometrical imperfections and, in particular, it can be used to perform "exact" or "approximate" (i.e., including only a few deformation modes) analyses. Concerning the solution of the system of GBT nonlinear equilibrium equations, the finite element method (FEM) constitutes the most efficient and versatile numerical technique and, thus, a beam FE is specifically developed for this purpose. The FEM implementation of the GBT post-buckling formulation is reported in some detail and then employed to obtain numerical results, which validate and illustrate the application and capabilities of the theory.
BUCKLING OF A LARGE RING STIFFENED PROLATE DOME UNDER EXTERNAL HYDROSTATIC PRESSURE
Authors: ROSS CARL T. F. , LITTLE ANDREW P. F. , BARTLETT COLIN
Published: December 2003

The paper reports on the buckling of a ring-stiffened hemi-ellipsoidal prolate dome under external hydrostatic pressure. The study was partly theoretical and partly experimental, where in the case of the latter, the finite element method was used. Comparison between experiment and theory was good. The effect of ring stiffening the dome was to increase its buckling resistance by a factor of 2.05.
INELASTIC BUCKLING OF RECTANGULAR STEEL PLATES USING A RAYLEIGH–RITZ METHOD
Authors: SMITH S. T. , BRADFORD M. A. , OEHLERS D. J.
Published: December 2003

The paper presents a Rayleigh–Ritz based non-discretization method of analysis for the inelastic local buckling of rectangular steel plates subjected to applied in-plane axial, bending and shear actions with various boundary conditions. Use is made of the pb-2 representation of the displacement function as the product of a domain polynomial and a boundary polynomial. The constitutive model for the plate is an adaptation of the von Mises yield criterion and the associated flow rule presented in an infinitesimal form, and which leads to an incremental and iterative method of solution. The convergence and accuracy of the solutions are demonstrated, and it is shown that the method of analysis is computationally feasible for the solution of inelastic bifurcative plate instability problems. A parametric study is then undertaken for a range of plate boundary conditions under various regimes of applied loading.
ANALYTICAL SOLUTION OF DYNAMIC ANALYSIS OF SHEAR FLEXIBLE CLAMPED RECTANGULAR PLATES
Authors: JOHN MARIAM JOSEPH , KABIR HUMAYUN R. H.
Published: December 2003

A study on the suitability of a set of solution functions in an analytical solution approach for the dynamic response of a clamped, moderately-thick plate subjected to a dynamic load is presented. The solution methodology involves obtaining free vibration responses using a recently developed analytical solution approach based on the double Fourier series equations proposed by Kabir and Chaudhuri, and applying the modal superposition method in solving the dynamic response. The equilibrium equations for the plate are defined by a set of three highly-coupled partial differential equations that are based on the Mindlin theory. The solution functions are assumed in the form of double Fourier series that satisfy the boundary conditions. The dynamic load considered is a step impulse load applied at the center of the plate. Results include convergence characteristics of transverse displacement and moment and variation of these quantities with respect to aspect ratios. These analytical solutions are useful for testing the accuracy of numerical methods.
AN IMPROVED RAYLEIGH–RITZ SUBSTRUCTURE SYNTHESIS METHOD ADOPTING MIXED COORDINATES
Authors: SCHEBLE MARIO , RAUSCHERT AGUSTÍN G. , CONVERTI JOSÉ
Published: December 2003

This paper presents an improvement of the Rayleigh–Ritz substructure synthesis method that retains all the advantages of the more elaborate existing versions. The displacement field in each component is represented by a set of simple non-admissible shape functions (generalized coordinates). These are subject to a transformation to mixed coordinates (physical and internal). The physical coordinates are defined where necessary to impose boundary conditions and geometrical compatibility. The internal coordinates are chosen in order to optimize the condition number of the matrices involved. Such a change of coordinates makes possible the use of the convenient assembling procedure of the Finite Element Method. The procedure, done in a systematic manner, leaves no free choice to the user and leads to an optimal numerical behavior. Several examples of applications are presented.
SCALING LAW AND PHYSICAL SIMILITUDE FOR BUCKLING AND VIBRATION OF ANTISYMMETRIC ANGLE-PLY LAMINATED CYLINDRICAL SHELLS
Authors: UNGBHAKORN VARIDDHI , SINGHATANADGID PAIROD
Published: December 2003

The similitude invariants and scaling laws for the buckling and free vibration of antisymmetric angle-ply laminated circular cylindrical shells were derived by directly applying the similitude transformation to the governing differential equations of the problem considered. The scaling laws relate the buckling load and natural frequency of a model to those of a prototype when the similarity requirements between the two systems are fulfilled. In the absence of experimental data, the validity of the scaling laws was verified by calculating theoretically the buckling loads and fundamental frequencies of vibration of the model and substituting them into the scaling laws to yield values for the prototype, which were then compared with those directly computed for the prototype. The numerical studies show that for the case of complete similitude with various stacking sequence, number of plies, and radius ratio, the solutions predicted by the similitude theory agree exactly with those obtained directly from the theory. Some typical partial similitude cases were also investigated. It was demonstrated that the partial similitude model with distortion in stacking sequence is reliable for predicting the behavior of the prototype. On the other hand, models with distortion in material properties are not recommended because of the existence of large discrepancies in the predicted results.
LSI-BASED EFFICIENT EMULATION OVERCOMING ALGORITHMIC RESTRICTIONS INHERENT IN QUANTUM COMPUTERS
Authors: FUJISHIMA MINORU
Published: December 2003

Quantum computers are believed to perform high-speed calculations, compared with conventional computers. However, the quantum computer solves NP (non-deterministic polynomial) problems at a high speed only when a periodic function can be used in the process of calculation. To overcome the restrictions stemming from the quantum algorithm, we are studying the emulation by a LSI (large scale integrated circuit). In this report, first, it is explained why a periodic function is required for the algorithm of a quantum computer. Then, it is shown that the LSI emulator can solve NP problems at a high speed without using a periodic function.
SURFACE LEAKAGE CURRENT RELATED $\frac{1}{f}$ NOISE IN NONILLUMINATED FOCAL PLANE ARRAY Hg1-xCdxTe DIODE
Authors: PEREZ J. P. , SIGNORET P. , MYARA M. , ASAAD I. , ORSAL B.
Published: December 2003

Experimental results are presented for current-voltage and dynamic resistance-voltage characteristics of Hg1-xCdxTe ion implanted n+-on-p junction photodiodes with x = 0,3. By measuring the temperature dependence of the dc characteristics in the temperature range [77 K, 175 K], it was found that the dark current can be represented with two components at low reverse-bias: diffusion and surface leakage current. Furthermore, reporting on electrical noise spectral density as a function of temperature and dark current, we assume that below 120 K, [Formula: see text] noise current is surface leakage current related.
Managing Knowledge Flows between High-Tech Firms and Universities: Empirical Evidence from the Biotechnology Industry in the UK
Authors: Salazar Alvarez Angel J.
Published: January 2004

The accelerating change and innovation in the biotechnology sector has increased the pressure on firms to challenge the traditional "Mode-one" approach to manage and transfer scientific and technological knowledge from university research centres. Firms, and universities, are increasingly adopting new and more complex approaches for the management and transfer of such knowledge and related innovations. This paper illustrates and conceptualises these emerging approaches from a strategic and knowledge management perspective. In so doing, this chapter draws from key theoretical contributions from the academic literature in order to explain the emerging management and transfer processes, which are identified in five specific University-Industry collaborations in the Biotechnology Sector in the United Kingdom. The paper integrates these transfer processes into a wider strategic framework, which would enable firms to successfully manage and internalise public scientific and technological knowledge.
Knowledge Sharing in a Co-Opetitive Environment: The Case of Business Clusters
Authors: Molina Maria , Yoong Pak
Published: January 2004

This paper reports preliminary results from a study that examines factors influencing knowledge sharing among members of business clusters based in Wellington, New Zealand. Business clusters are local concentrations of competitive firms in related industries that do business with each other. Earthquake Engineering, Creative Capital, Natural Hazards, Optics and Software are examples of clusters stu-died in this paper. However, some of the companies in many business clusters are direct competitors in the local arena and they are often expected to co-operate and share business knowledge with each other when they are considering bidding for international projects or contracts. This knowledge may be considered to have provided each company with a competitive advantage. Therefore, trying to successfully operate in this mixed environment of "co-operation" and "competition" can pose a dilemma for many members of business clusters. For this study, a three-stage data collection strategy was used: a focus group, online voting exercise and individual interviews. Representatives from seven business clusters in the Wellington region took part in this study. Analysis of the data revealed that several factors do influence knowledge sharing in business clusters, such as: sharing a common understanding and commitment to the cluster idea; initial respect and trust between cluster members; and having strong, charismatic cluster champions/leaders. These factors will be explored and the implications for practice and research will also be discussed.
Understanding Organizational Learning Through Knowledge Management
Authors: Sharma Rumesh Kumar
Published: January 2004

The literature on organizational learning and knowledge management over the last decade has been extensive and far-reaching. This paper analyses the proliferation of these concepts along different disciplinary perspectives by tracing their evolution. The analysis reveals that organizational learning is a diffused; ill-defined concept with little consideration made for its practical application. Knowledge management on the other hand is a medley of different approaches but lack a unifying vision. As a result, it is difficult to establish synergistic relationship between these two concepts. An attempt is made to show how knowledge management models may be used to facilitate organizational learning. The models discussed include the Intellectual Capital Model, the Socially Constructed Model and the Knowledge Category Model. Each of these models is assessed in order to determine how they contribute towards the practical realization of organizational learning. The review shows that although these models differ in terms of how knowledge is perceived and in terms of the dynamics of learning involved, each of them has the capacity to contribute in unique ways towards organizational learning. The paper proposes that attempts to seek synergistic relationships that link organizational learning and knowledge management should be examined more closely to facilitate the practical realization of organizational learning.
Applying Knowledge Management in Higher Education: The Creation of a Learning Organisation
Authors: Metaxiotis Kostas , Psarras John
Published: January 2004

Knowledge Management (KM) has recently received considerable attention in the computer information systems community and is continuously gaining interest by industry, enterprises and academia. As we are moving into an era of "knowledge capitalism", knowledge management in combination with information management will play a fundamental role towards the success of transforming individual knowledge into organizational knowledge. Higher education (HE) institutions are in the knowledge business, since they are involved in knowledge creation, dissemination and learning. The increasing economic importance of knowledge, which nowadays redefines the links among education, work and learning, makes the role of KM in HE crucial.

In this framework, this paper presents the key concepts of human-computer interaction in knowledge management, discusses their applicability to HE and proposes the creation of learning organisations in HE institutions, as an innovative way to apply KM to HE.
E-Learning in Higher Educational Institutions in Indonesia
Authors: Kuntoro Ratna Dewi , Al-Hawamdeh Suliman
Published: January 2004

Private and academic institutions are embracing E-learning as an attempt to improve the learning process, encourage knowledge transfer and compliment their existing learning environment. For many countries with a large population, limited resources and remote geographical areas like Indonesia, E-learning holds the key to better education and provide better access to knowledge resources. E-learning is still new in Indonesia and there are not many studies reported in the literature. This study aimed to provide some ideas about the state of E-learning in Indonesia, specifically in higher education institutions. A survey was carried out to reveal the state of E-learning in higher education institutions in Indonesia. Sample of the population consists of lecturers, developers and researchers who work for higher education institutions in Indonesia. While the study showed that most of the E-learning projects are new and the level of participation is slow, the quality of E-learning courses is perceived as fair. As E-learning development in Indonesia is still in its early stages, serious efforts are needed to facilitate E-learning in higher institutions. The study identified infrastructure problems and staffs' reluctance to adopt E-learning as the main problems for the slow implementation and adoption of E-learning. Despite these problems, E-learning is expected to gain momentum in Indonesia as it is perceived as an effective way to educate the population of Indonesia.
Business Intelligence from Web Usage Mining
Authors: Abraham Ajith
Published: January 2004

The rapid e-commerce growth has made both business community and customers face a new situation. Due to intense competition on the one hand and the customer's option to choose from several alternatives, the business community has realized the necessity of intelligent marketing strategies and relationship management. Web usage mining attempts to discover useful knowledge from the secondary data obtained from the interactions of the users with the Web. Web usage mining has become very critical for effective Web site management, creating adaptive Web sites, business and support services, personalization, network traffic flow analysis and so on. This paper presents the important concepts of Web usage mining and its various practical applications. Further a novel approach called "intelligent-miner" (i-Miner) is presented. i-Miner could optimize the concurrent architecture of a fuzzy clustering algorithm (to discover web data clusters) and a fuzzy inference system to analyze the Web site visitor trends. A hybrid evolutionary fuzzy clustering algorithm is proposed to optimally segregate similar user interests. The clustered data is then used to analyze the trends using a Takagi-Sugeno fuzzy inference system learned using a combination of evolutionary algorithm and neural network learning. Proposed approach is compared with self-organizing maps (to discover patterns) and several function approximation techniques like neural networks, linear genetic programming and Takagi–Sugeno fuzzy inference system (to analyze the clusters). The results are graphically illustrated and the practical significance is discussed in detail. Empirical results clearly show that the proposed Web usage-mining framework is efficient.
A Practical Approach: Localization-Based Global Metadata Registry for Progressive Data Integration
Authors: Jeong Dongwon , Baik Doo-Kwon , Park Soo-Hyun
Published: January 2004

Until now, many researches based on metadata have been studied for data integration in various fields. However, there exists a problem in that the existing approaches still require much cost to build an initial guideline, which is sometimes called as a registry, global metadata set. The most critical problem of existing researches is that the researches have not been seriously considered on the corresponding domain properties- data level and user level. Most of all, it is difficult to create a standardized guideline on the entire data with the restricted cost. In this paper, we propose a method to progressively integrate databases considering the domain properties under limited cost. For instance, in scientific data, general users are interested in the simple and easy scientific data, which has low complexity. On the other hand, scientists or experts can utilize more detailed and specialized data as well as the general data. It means that an initial data quantity to be integrated is determined by the relationship of the domain properties. We show the implementation results of applying it to scientific data managed by Korea Institute of Science and Technology Information. The proposed method provides a progressive data integration mechanism, and especially it gives successful and efficient output on the creation of a standard guideline in the situation where the given cost is limited.
Regional Internet Exchange for MENA Countries and its Performance Evaluation
Authors: Al-Zoubaidi A.
Published: January 2004

In this paper we propose a Regional Internet Exchange (RIX) scheme for MENA countries intra-regional traffic, compared with the existing situation for Internet service provision. The RIX architecture is proposed, implemented, and evaluated using simulation. Simultaneous comparative performance evaluation of Internet service provision for the existing and the proposed scenarios are presented. It is focused to measure utilization, message delays, access time and client perceived latencies performance metrics. The study shows that the proposed scheme results in less international bandwidth utilization and it reduces significantly the access time and most importantly it is inherently cost-effective.
C-Peptide Colocalizes with Macrophages in Early Arteriosclerotic Lesions of Diabetic Subjects and Induces Monocyte Chemotaxis In Vitro
Authors: Marx Nikolaus , Walcher Daniel , Raichle Claudia , Aleksic Milos , Bach Helga , Grüb Miriam , Hombach Vinzenz , Libby Peter , Zieske Arthur , Homma Satoki , Strong Jack
Published: January 2004

Objective—

Increased levels of C-peptide, a cleavage product of proinsulin, circulate in patients with insulin resistance and early type 2 diabetes, a high-risk population for the development of a diffuse and extensive pattern of arteriosclerosis. This study tested the hypothesis that C-peptide might participate in atherogenesis in these patients.

Method and Results—

We demonstrate significantly higher intimal C-peptide deposition in thoracic artery specimens from young diabetic subjects compared with matched nondiabetic controls as determined by immunohistochemical staining. C-peptide colocalized with monocytes/macrophages in the arterial intima of artery specimen from diabetic subjects. In vitro, C-peptide stimulated monocyte chemotaxis in a concentration-dependent manner with a maximal 2.3±0.4-fold increase at 1 nmol/L C-peptide. Pertussis toxin, wortmannin, and LY294002 inhibited C-peptide–induced monocyte chemotaxis, suggesting the involvement of pertussis toxin-sensitive G-proteins as well as a phosphoinositide 3-kinase (PI3K)-dependent mechanism. In addition, C-peptide treatment activated PI3K in human monocytes, as demonstrated by PI3K activity assays.

Conclusion—

C-peptide accumulated in the vessel wall in early atherogenesis in diabetic subjects and may promote monocyte migration into developing lesions. These data support the hypothesis that C-peptide may play an active role in atherogenesis in diabetic patients and suggest a new mechanism for accelerated arterial disease in diabetes.
Transduction of the N-Terminal Fragments of MYPT1 Enhances Myofilament Ca
2+
Sensitivity in an Intact Coronary Artery
Authors: Hirano Katsuya , Derkach Dmitry N. , Hirano Mayumi , Nishimura Junji , Takahashi Shosuke , Kanaide Hideo
Published: January 2004

Objective—

The region of the 110 kDa regulatory subunit (MYPT1) of smooth muscle myosin phosphatase involved in the regulation of contraction was determined under physiological conditions.

Methods and Results—

Using HIV Tat protein-mediated protein transduction, the N-terminal fragments of MYPT1 were introduced to the intact porcine coronary arterial strips. Pre-incubation with 3 μmol/L TAT-MYPT1
1–374
, a construct containing the Tat peptide and the residues 1 to 374 of MYPT1, for 15 minutes augmented (2.4-fold) the subsequent contraction induced by adding 1.25 mmol/L of extracellular Ca
2+
under 118 mmol/L K
+
depolarization, with no augmentation of the [Ca
2+
]
i
elevation. The deletion of the Tat peptide, MYPT1
1–374
, abolished the augmenting effect. TAT-MYPT1
1–296
demonstrated a weaker but significant augmentation (1.7-fold). However, TAT-MYPT1
1–171
, TAT-MYPT1
39–374
, TAT-MYPT1
39–296
, and TAT-MYPT1
297–374
had no augmenting activity. The myosin light chain phosphorylation level as a function of extracellular Ca
2+
concentrations was shifted to the left in the strips pretreated with TAT-MYPT1
1–374
compared with the control.

Conclusions—

Region 1 to 296 was the minimal region involved in the enhancement of contraction, and region 297 to 374 played a supplemental role. These results suggested that the interaction mainly between catalytic subunit and MYPT1 play a critical role in the regulation of the endogenous myosin phosphatase in intact smooth muscle.
Pulmonary Vein Denervation Enhances Long-Term Benefit After Circumferential Ablation for Paroxysmal Atrial Fibrillation
Authors: Pappone Carlo , Santinelli Vincenzo , Manguso Francesco , Vicedomini Gabriele , Gugliotta Filippo , Augello Giuseppe , Mazzone Patrizio , Tortoriello Valter , Landoni Giovanni , Zangrillo Alberto , Lang Christopher , Tomita Takeshi , Mesas Cézar , Mastella Elio , Alfieri Ottavio
Published: January 2004

Background—

There are no data to evaluate the relationship between autonomic nerve function modification and recurrent atrial fibrillation (AF) after circumferential pulmonary vein ablation (CPVA). This study assesses the incremental benefit of vagal denervation by radiofrequency in preventing recurrent AF in a large series of patients undergoing CPVA for paroxysmal AF.

Methods and Results—

Data were collected on 297 patients undergoing CPVA for paroxysmal AF. Abolition of all evoked vagal reflexes around all pulmonary vein ostia was defined as complete vagal denervation (CVD) and was obtained in 34.3% of patients. Follow-up ended at 12 months. Heart rate variability attenuation, consistent with vagal withdrawal, was detectable for up to 3 months after CPVA, particularly in patients with reflexes and CVD, who were less likely to have recurrent AF than those without reflexes (
P
=0.0002, log-rank test). Only the percentage area of left atrial isolation and CVD were predictors of AF recurrence after CPVA (
P
<0.001 and
P
=0.025, respectively).

Conclusions—

This study suggests that adjunctive CVD during CPVA significantly reduces recurrence of AF at 12 months.
Developmental Control of Titin Isoform Expression and Passive Stiffness in Fetal and Neonatal Myocardium
Authors: Lahmers Sunshine , Wu Yiming , Call Douglas R. , Labeit Siegfried , Granzier Henk
Published: January 2004

Developmental changes in contractile behavior are known to occur during fetal and postnatal heart development. In this study, we examined whether adaptations take place in titin. A range of species was used to evaluate titin isoform expression and altered function during cardiac muscle development. A novel titin exon microarray that allows all 363 titin exons to be monitored simultaneously was used for transcript studies. Results reveal expression of fetal titin isoforms, characterized by additional spring elements both in the tandem Ig and PEVK region of the molecule. At the protein level, the fetal cardiac isoform predominates in fetal and neonatal myocardium and gradually disappears during postnatal development with a time course that varies in different species. Passive myocardium, contrary to previous reports, was found to be less stiff in the neonate than in the adult. This can be explained by the unique spring composition of fetal cardiac titin expressed by the neonate. Changes in titin expression are likely to impact functional transitions and diastolic filling behavior during development of the heart.
Hemicraniectomy for Massive Middle Cerebral Artery Territory Infarction
Authors: Gupta Rishi , Connolly E. Sander , Mayer Stephan , Elkind Mitchell S.V.
Published: January 2004

Background and Purpose—

Hemicraniectomy and durotomy have been proposed in many small series to relieve intracranial hypertension and tissue shifts in patients with large hemispheric infarcts, thereby preventing death from herniation. Our objective was to review the literature to identify patients most likely to benefit from hemicraniectomy.

Methods—

All available individual cases from the English literature were reviewed and analyzed to determine whether age, vascular territory of infarction, side of infarction, reported time to surgery, and signs of herniation predict outcome in patients after hemicraniectomy. All studies included were retrospective and uncontrolled; there were no randomized controlled trials.

Results—

Of 15 studies screened, 12 studies describing 129 patients met the criteria for analysis; 9 patients treated at our institution were added, for a total of 138 patients. After a minimum follow-up of 4 months, 10 patients (7%) were functionally independent, 48 (35%) were mildly to moderately disabled, and 80 (58%) died or were severely disabled. Of 75 patients who were >50 years of age, 80% were dead or severely disabled compared with 32% of 63 patients ≤50 years of age (
P
<0.00001). The timing of surgery, hemisphere infarcted, presence of signs of herniation before surgery, and involvement of other vascular territories did not significantly affect outcome.

Conclusions—

Age may be a crucial factor in predicting functional outcome after hemicraniectomy in patients with large middle cerebral artery territory infarction.
Differential Pattern of Tissue Plasminogen Activator–Induced Proximal Middle Cerebral Artery Recanalization Among Stroke Subtypes
Authors: Molina Carlos A. , Montaner Joan , Arenillas Juan F. , Ribo Marc , Rubiera Marta , Alvarez-Sabín José
Published: January 2004

Background and Purpose—

We aimed to evaluate the timing, speed, and degree of tissue plasminogen activator (tPA)–induced recanalization in patients with proximal middle cerebral artery (MCA) occlusion of different stroke subtypes.

Methods—

We evaluated 72 patients with acute stroke caused by proximal MCA occlusion treated with intravenous tPA in <3 hours. Transcranial Doppler monitoring of recanalization was conducted during tPA infusion and at 6 hours. Strokes were categorized as large-vessel disease strokes, cardioembolic strokes, or strokes of undetermined origin according to Trial of Org 10172 in Acute Stroke Treatment criteria.

Results—

During 1-hour tPA infusion, recanalization occurred in 34 patients (47%); 32% showed a sudden, 50% showed a stepwise, and 18% showed a slow pattern of recanalization. One-hour recanalization was more frequent in patients with cardioembolic stroke (59%) compared with large-vessel disease (8%) and undetermined origin (50%) strokes. A cardiac source of emboli was identified in 81% of patients who showed a sudden clot breakup during tPA infusion. Rate of complete recanalization at 6 hours was higher (
P
=0.006) in patients with cardioembolic stroke (50%) compared with other stroke subtypes (27%). Sudden recanalization was associated (
P
=0.002) with a higher degree of neurological improvement at 24 hours compared with stepwise, slow, and no recanalization. A graded response in long-term outcome was observed in relation to the speed of clot lysis during tPA administration.

Conclusions—

We demonstrate that the pattern of tPA-induced MCA recanalization differs among stroke subtypes. Early recanalization was more frequent, faster, and more complete in patients with cardioembolic stroke compared with other stroke subtypes.
Continuous 15-Year Decrease in Incidence and Mortality of Stroke in Finland
Authors: Sivenius Juhani , Tuomilehto Jaakko , Immonen-Räihä Pirjo , Kaarisalo Minna , Sarti Cinzia , Torppa Jorma , Kuulasmaa Kari , Mähönen Markku , Lehtonen Aapo , Salomaa Veikko
Published: January 2004

Background and Purpose—

The purpose of this study was to analyze the incidence and mortality trends in stroke events among persons 25 to 74 years of age in Finland during 1983 to 1997.

Methods—

The population-based FINSTROKE register recorded 5650 new strokes among persons 25 to 74 years of age in 2 geographical areas of Finland: 2770 in the Kuopio area (east central Finland) and 2880 in Turku (southwestern Finland). Of these, 3065 were men and 2585 were women.

Results—

The rates of acute stroke events fell during the whole study period in both men and women. In both FINSTROKE areas combined, the average annual decline in the age-standardized incidence of first stroke events was 2.0% (95% confidence interval [CI], −2.8 to −1.2;
P
<0.001) among men and 1.7% (95% CI, −2.6 to −0.8;
P
<0.001) among women. The decline in the incidence of ischemic stroke was even steeper, 2.9%/y (95% CI, −4.9 to −1.1;
P
<0.001) among men and 3.1%/y (95% CI, −5.0 to −1.1;
P
<0.001) among women, whereas the incidence of intracerebral hemorrhage and subarachnoid hemorrhage did not change. Mortality from all stroke events declined in the FINSTROKE areas by 3.7%/y (95% CI, −5.3 to −2.0;
P
<0.001) among men and by 4.1%/y (95% CI, −5.9 to −2.4;
P
<0.001) among women. The 28-day case fatality of all stroke events also tended to decline, but the decline was of borderline statistical significance only (
P
=0.07 among men,
P
=0.05 among women).

Conclusions—

Incidence and mortality of stroke events declined significantly in these 2 register areas in Finland during the 15-year period of 1983 to 1997.
Periodontal Disease as a Risk Factor for Ischemic Stroke
Authors: Grau Armin J. , Becher Heiko , Ziegler Christoph M. , Lichy Christoph , Buggle Florian , Kaiser Claudia , Lutz Rainer , Bültmann Stefan , Preusch Michael , Dörfer Christof E.
Published: January 2004

Background and Purpose—

Chronic infectious diseases may increase the risk of stroke. We investigated whether periodontal disease, including periodontitis and gingivitis, is a risk factor for cerebral ischemia.

Methods—

We performed a case-control study with 303 patients examined within 7 days after acute ischemic stroke or transient ischemic attack, 300 population controls, and 168 hospital controls with nonvascular and noninflammatory neurological diseases. All subjects received a complete clinical and radiographic dental examination. The individual mean clinical attachment loss measured at 4 sites per tooth served as the main indicator for periodontitis.

Results—

Patients had higher clinical attachment loss than population (
P
<0.001) and hospital (
P
=0.010) controls. After adjustment for age, sex, number of teeth, vascular risk factors and diseases, childhood and adult socioeconomic conditions, and lifestyle factors, the risk of cerebral ischemia increased with more severe periodontitis. Subjects with severe periodontitis (mean clinical attachment loss >6 mm) had a 4.3-times-higher (95% confidence interval, 1.85 to 10.2) risk of cerebral ischemia than subjects with mild or without periodontitis (≤3 mm). Severe periodontitis was a risk factor in men but not women and in younger (<60 years) but not older subjects. Periodontitis increased the risk of cerebral ischemia caused by large-artery atherosclerosis, cardioembolism, and cryptogenic etiology. Gingivitis and severe radiologic bone loss were also independently associated with the risk of cerebral ischemia, whereas caries was not.

Conclusions—

Our study indicates that periodontal disease, a treatable condition, is an independent risk factor for cerebral ischemia in men and younger subjects.
Cortical Microinfarcts and Demyelination Significantly Affect Cognition in Brain Aging
Authors: Kövari Enikö , Gold Gabriel , Herrmann François R. , Canuto Alessandra , Hof Patrick R. , Michel Jean-Pierre , Bouras Constantin , Giannakopoulos Panteleimon
Published: January 2004

Background and Purpose—

Microvascular lesions are common in brain aging, but their clinical impact is debated. Methodological problems such as the masking effect of concomitant pathologies may explain discrepancies among previous studies. To evaluate the cognitive consequences of such lesions, we prospectively investigated elderly individuals with various degrees of cognitive impairment but without significant neurofibrillary tangle pathology or macrovascular lesions.

Methods—

This was a clinicopathological study of 45 elderly individuals. Cognitive status was assessed prospectively with the Clinical Dementia Rating (CDR) scale; neuropathological evaluation included Aβ-protein deposition staging and bilateral semiquantitative assessment of cortical microinfarcts, focal cortical and white matter glioses, and diffuse white matter and periventricular demyelination.

Results—

In a univariate logistic regression model, cortical microinfarcts explained 36.1% of the variability in CDR; periventricular demyelination, 10.6%; and diffuse white matter demyelination, 4.6%. After controlling for age and Aβ-protein deposition, cortical microinfarcts were the best predictor of cognitive status (19.9% of CDR variability), whereas periventricular and diffuse white matter demyelination accounted for 9.7% and 5.4% of CDR variability, respectively. Altogether, these 3 types of microvascular lesions explained 27.9% of the clinical variability. Focal cortical and white matter glioses were not related to clinical outcome.

Conclusions—

Our data imply that cortical microinfarcts and both periventricular and deep white matter demyelination contribute significantly to the progression of cognitive deficits in brain aging. In contrast, the neuropathological evaluation of focal cortical and white matter gliosis has no clinical validity.
Essential role of HGF (hepatocyte growth factor) in blood formation in Xenopus
Authors: Koibuchi Nobutaka , Kaneda Yasufumi , Taniyama Yoshiaki , Matsumoto Kunio , Nakamura Toshikazu , Ogihara Toshio , Morishita Ryuichi
Published: January 2004

In this study, we investigated the role of hepatocyte growth factor (HGF) in blood formation during Xenopus development. First, we examined the gene expression of HGF and its receptor, c-met, by whole-mount in situ hybridization during development. Strong signals of HGF as well as c-met were detected early in the developing ventral mesoderm, which later gives rise to the ventral blood island. Furthermore, to study the role of HGF, we blocked the HGF signaling pathway in Xenopus embryos by using truncated c-met lacking the tyrosine kinase domain. Injection of truncated c-met mRNA resulted in a marked decrease in the number of circulating blood cells. Similar results were obtained using morpholino antisense HGF oligonucleotides. Moreover, we also analyzed the expression of several early primitive blood markers in the blood island of these embryos. RNA in situ analysis revealed a significant reduction (or absence) of stem cell leukemia (SCL), α-globin, and GATA-1 expression, but not GATA-2 expression. In contrast, no significant difference was observed in the levels of expression of early definitive blood markers, SCL, GATA-2, and GATA-3 in the dorsolateral plate, as analyzed by in situ hybridization. Overall, the present study demonstrated that HGF is necessary for primitive hematopoiesis by regulating the expression of SCL. (Blood. 2004;103:3320-3325)