bluuebunny/crossref_metadata_2025 huggingface dataset:
ANTERIOR BENDING ON WHOLE VERTEBRAE USING CONTROLLED BOUNDARY CONDITIONS FOR MODEL VALIDATION
Authors: Sapin Emilie , Chan Frédéric , Ayoub Ghazi , Roux Christian , Skalli Wafa , Mitton David
Published: July 2009

Most of the biomechanical experiments, which validate vertebral finite-element models, deal with vertebral bodies in axial compression. In standing position, gravity loads can induce bending on the last thoracic and first lumbar vertebrae. Hence, the purpose of the study was to evaluate the strength of vertebrae submitted to anterior bending. The boundary conditions were carefully assessed for further validation of finite-element models. Fifteen vertebrae (T11–L2) were tested until failure. The load was applied on the anterior part of the vertebral body and distributed to the whole vertebral body through a polymethylmetacrylate layer. The 3D position of the origin of the force relative to the vertebra was assessed using a motion-capture system and 3D reconstructions of the testing device. The mean failure load was equal to 2098 N. Ninety-five percent of the vertebrae failed through a vertical displacement smaller than 1.5 mm. Rotations were weak during the test (< 1°), therefore the protocol can be simplified by removing the motion capture system if the initial 3D origin of the load is known. To our knowledge, it is the first protocol that quantifies the strength of whole vertebrae under anterior bending. It collects with accuracy all the data necessary for one-to-one vertebral finite-element model validations.
CLINICAL OUTCOMES FOLLOWING LUMBAR SURGERY AUGMENTED WITH DIAM INTERSPINOUS IMPLANT
Authors: Crawford Rebecca J. , Price Roger I. , Malone Quentin , Singer Kevin P.
Published: July 2009

Posterior interspinous dynamic stabilization is used increasingly in the treatment of lumbar degenerative spinal conditions, with preliminary evidence for its clinical and biomechanical efficacy emerging. The need remains to define patients who respond best to this form of surgery. This study examined clinical outcomes in 39 patients (21 females) with defined lumbar spinal pathologies, for two years after lumbar surgery augmented with the Device for Intervertebral Assisted Motion (DIAM). Anatomical patient categorization revealed involvement of disc (n=25/39) and facet (n=14/39) lumbar pathology, with clinical indications for surgery being: segmental instability (n=21/39); nerve root compression (n=11/39); and facet joint pain syndrome (n=7/39). Pain, function and satisfaction data were derived from MODEMS self-report questionnaires, which were collected prospectively over a two-year post-operative period. Results showed that L4-5 and L5-S1 were the most common DIAM-implanted spinal levels. Clinically significant post-operative improvement in pain (23.4%) and function (13.5%) occurred between three and twenty-four months. Eleven (of 39) required further lumbar surgery. Nineteen (of 28) were more satisfied at 24 months post-operatively compared to baseline. Disc involvement and segmental instability were the most common presenting lumbar segmental pathologies, yet the least successful in response to surgery augmented with DIAM. Patients with facet involvement reported superior improvement post-operatively compared with those with disc involvement. Patients with facet joint disease demonstrate better outcomes at 24 months following lumbar surgery augmented with DIAM posterior interspinous dynamic stabilization, compared with those presenting with disc pathology.
MARKOVIAN PROJECTION ONTO A DISPLACED DIFFUSION: GENERIC FORMULAS WITH APPLICATIONS
Authors: ANTONOV A. , MISIRPASHAEV T.
Published: July 2009

We develop a systematic approach to Markovian projection onto an effective displaced diffusion, and work out a set of computationally efficient formulas valid for a large class of non-Markovian underlying processes. The generic derivation is followed by applications, including the calculation of FX options in cross-currency models and swaption pricing in LIBOR Market Models, where we are able to recover in an unambiguous way many known analytical approximations and derive several new ones.
MULTIPLE RESCINDABLE OPTIONS AND THEIR PRICING
Authors: DOKUCHAEV NIKOLAI
Published: July 2009

We suggest a modification of an American option such that the option holder can exercise the option early before the expiration and can revert later this decision to exercise; it can be repeated a number of times. This feature gives additional flexibility and risk protection for the option holder. A classification of these options and pricing rules are given. We found that the price of some call options with this feature is the same as for the European call. This means that the additional flexibility costs nothing, similarly to the situation with American and European call options. For the market model with zero interest rate, the price of put options with this feature is also the same as for the standard European put options. Therefore, these options can be more competitive than the standard American options.
PCA-BASED EX-ANTE FORECASTING OF SWAP TERM STRUCTURES
Authors: BLASKOWITZ OLIVER , HERWARTZ HELMUT
Published: July 2009

In this study, we forecast the term structure of EURIBOR swap rates by means of rolling vector autoregressive (VAR) models. In advance, a principal component analysis (PCA) is adopted to reduce the dimensionality of the term structure. To statistically assess the forecasting performance for particular rates and the level, slope and curvature of the swap term structure, we rely on the Henrikkson–Merton statistic. Economic performance is investigated by means of cash flows implied by alternative trading strategies. Finally, a data-driven, adaptive model selection strategy to "predict the best forecasting model" out of a set of 100 alternative PCA/VAR implementations is shown to outperform forecasting schemes that rely on global homogeneity of the term structure.
INVESTMENT TIMING UNDER REGIME SWITCHING
Authors: ELLIOTT ROBERT J. , MIAO HONG , YU JIN
Published: July 2009

We investigate the optimal investment timing strategy in a real option framework. Depending on the state of the economy, whose changes are modeled by a Markov chain, the investment cost can take one of two values. The optimal investment timing decision is determined by finding the free boundary of a perpetual American option. Three investment timing policies, based on different assumptions of investors' information sets, are determined and compared. In the full information case, a significantly earlier optimal exercising time is indicated. We show that an optimal-timing policy suggested by the conventional real option model might ruin the investment opportunities.
A LITERATURE REVIEW AND CLASSIFICATION OF ENTERPRISE SOFTWARE SELECTION APPROACHES
Authors: ŞEN CEYDA GÜNGÖR , BARAÇLI HAYRİ , ŞEN SELÇUK
Published: July 2009

The evaluation and selection of enterprise software has become increasingly difficult for decision makers due to a large number of software products available for many applications. Therefore, systematic and repeatable approaches are needed in order to select the appropriate product that best meets the customer requirements. In this paper, we present a literature review and classification of enterprise software selection approaches from the period 1982–2007. In addition to classifying the selected approaches by functional perspective, the decision-making methods used by these approaches in the generic phases of software selection process are also presented. Results are summarized with comprehensive classification tables. This study is intended as a source for academics and practitioners alike interested in software selection problem, especially those who want to see alternative decision-making techniques that can be used to support the every single step of software selection process.
A NEW METHOD OF MEDICAL IMAGE RETRIEVAL BASED ON COLOR–TEXTURE CORRELOGRAM AND GTI MODEL
Authors: TAI XIAO-YING , WANG LI-DONG , CHEN QIN , FUJI REN , KENJI KITA
Published: July 2009

This paper presents a method for endoscopic image retrieval based on color–texture correlogram and Generalized Tversky's Index (GTI) model. First we define a new image feature named color–texture correlogram, which is the extension of color correlogram. The texture image extracted by texture spectrum algorithm is combined with color feature vector, and then we calculate the spatial correlation of color–texture feature vector. Similarity metric is also the key technology during domain of image retrieval, GTI model is used in medical image retrieval for similarity metric, and the technique of relevance feedback is used in the algorithm to enhance the efficiency of retrieval. Experimental results show that the method discussed in this paper is much more effective.
A DECISION SUPPORT SYSTEM FOR THE ENVIRONMENTAL IMPACT OF ICT AND E-BUSINESS
Authors: YI LAN , THOMAS HYWEL R.
Published: July 2009

Information and communication technologies (ICT) and e-business are affecting our economic progress, social development, and the environment profoundly and in a complex manner. As an emerging field of research, significant interests have been aroused but quantitative studies are rather limited. Traditional systematic approaches for impact studies have been found to be insufficient to deal with this research topic. In order to further explore the relationship between ICT/e-business and the environment, the approach adopted in this study aimed to simulate how ICT/e-business indicators interact with environmental indicators quantitatively. Owing to lack of data and information in the current area in government bodies/councils/research institutes, two questionnaire surveys were conducted. Details of the data collection progress are provided. An artificial neural network (ANN) approach, embedded in a more predictive and empirical model, is suggested herein as a new methodology and possible solution. Furthermore an expert decision support system (EDSS), built around these neural networks with a user-friendly interface and being able to post-process data to information, is developed. The system could be used, for example, by an individual company to analyze how its ICT/e-business adoptions influence its environmental performance.
A MULTICRITERIA DECISION SUPPORT SYSTEM FOR COMPETENCE-DRIVEN PROJECT PORTFOLIO SELECTION
Authors: STUMMER CHRISTIAN , KIESLING ELMAR , GUTJAHR WALTER J.
Published: July 2009

The systematic and proactive development of human resources is of major importance in organizations that rely heavily on the competencies of their employees when engaging in innovative endeavors. Human capital, however, is not only a resource required for conducting research, but also the eventual result of that research. When selecting a research portfolio, the decision-maker (DM) thus needs to take into consideration both current and future competence requirements, as well as other financial and nonfinancial objectives and constraints. We introduce a proper multicriteria decision support system (MCDSS) that first determines the set of Pareto-efficient solutions and then allows the DM to interactively filter and/or explore this set in various ways. Its practical application is demonstrated by means of a showcase at the Electronic Commerce Competence Center (EC3) in Vienna, Austria.
PROTOTYPING OF DIFFRACTIVE GRATING OPTICS FOR SENSOR APPLICATION BY AN INTEGRATED PROBE-BASED SYSTEM
Authors: FOK LO-MING , LIU YUN-HUI , LI WEN J.
Published: July 2009

Diffractive Optical Elements (DOE) are often associated with the use of laser beam shaping equipment. They can be controlled and verified flexibly according to application. This paper demonstrates experimentally the lithography technique used to fabricate a DOE with precisely aligned pattern on a polymer surface. We have designed and fabricated a grating on the lens surface using the direct lithography by an Atomic Force Microscope. A description of the optical design is presented along with a discussion on the integrated manipulation system. The fabrication process has been proven to be cost efficient and reliable. It is believed that this technique can also transfer onto a complicated DOE.
ROBUST EXPONENTIAL STABILITY OF STOCHASTIC TIME-DELAY SYSTEMS WITH UNCERTAINTIES AND NONLINEAR PERTURBATIONS
Authors: YAN HUAICHENG , MENG MAX Q.-H. , HUANG XINHAN , ZHANG HAO
Published: July 2009

In this paper, the delay-dependent robust exponential mean-square stability analysis problem is considered for a class of uncertain stochastic systems with time-varying delay and nonlinear perturbations. Some sufficient conditions on delay-dependent robust exponential stability in the mean square are established in terms of linear matrix inequalities (LMIs) by exploiting a novel Lyapunov–Krasovskii functional and by making use of zero equations methods. These developed results indicate less conservatism than the existing ones due to the introduction of some free weighting matrices which can be selected properly. The new delay-dependent stability criteria are expressed as a set of LMIs, which can be readily solved by using standard numerical software. Numerical examples are provided to demonstrate the effectiveness and the applicability of the proposed criteria.
ABNORMAL SECTIONS DETECTION BASED ON INTER-FRAMES INFORMATION IN VIDEO SEQUENCE
Authors: WANG WEI , WANG RUNSHENG , GAO WEI
Published: July 2009

An approach is proposed for abnormal sections detection and rank classification in video sequences. In this approach, we give the definition of the abnormality of the video sections and create an abnormal factor to evaluate the abnormality. Firstly, the histogram is selected to describe the color change in the section, and then the histograms of the frames selected from the section compose the histogram matrix. In order to improve the process efficiency, the principal components analysis is used to reduce dimensions of the histogram matrix. Secondly, the information of frames differences is used to describe the motion change information, and the information twice frame difference is used to describe the change rate. Lastly, the results from the features are fused to get the final result. This method is experimented with some samples. The results show that this method can realize the abnormal detection and rank classification of video sequences, and the results are better than the other related techniques.
FORCE CONTROL OF A REHABILITATION WALKER FOR STANDING ASSISTANCE WITH STABILITY
Authors: CHUGO DAISUKE , TAKASE KUNIKATSU
Published: July 2009

This paper proposes a walker system with power assistance device for standing-up motion. Our system focuses on family use for aged people who need nursing in their daily life. Our key ideas are based on two topics. The first topic is new assistance manipulator mechanism with four parallel linkages. Our proposed manipulator mechanism requires only smaller actuators and realizes rigid structure with lighter linkages compared with general manipulator. Thus, we can design our assistance system compactly with low-cost using our mechanism. The second topic is the combination of force and position control. According to the patient's posture during standing-up, our control system selects more appropriate control method from them. Furthermore, the walker coordinates its assistance position and maintains the stable posture of the patient during standing assistance. We use the reference of standing-up motion which is based on the typical standing-up motion by a nursing specialist for realizing the natural assistance. The performance of our proposed assistance system is verified by experiments using our prototype.
DEFINING KPI SETS FOR INDUSTRIAL RESEARCH ORGANIZATIONS — A PERFORMANCE MEASUREMENT APPROACH
Authors: SAMSONOWA TATJANA , BUXMANN PETER , GERTEIS WOLFGANG
Published: July 2009

In today's challenging economic climate it is more important than ever for companies to acquire comparable competitive advantage in their market. While previous research has investigated the performance measurement of R&D as a whole organization, very little research has been done into the performance management for just the research function itself. This, however, is of particular interest to larger organizations. This paper (1) introduces a framework for performance measurement for industrial research, and (2) presents a set of clusters, representing the content dimension for measuring research organizations. Based on the clusters, we were able to evaluate the extent to which performance measurement in practice in different companies can be compared. We discovered that the clusters follow a particular consistent distribution across organizations when the clusters are ranked by importance. For this empirical analysis, data was collected through in-depth case studies including more than 60 interviews and thorough document analyses.
THE ROLE OF ABSORPTIVE CAPACITY IN FACILITATING "OPEN INNOVATION" OUTCOMES: A STUDY OF AUSTRALIAN SMEs IN THE MANUFACTURING SECTOR
Authors: HUANG FANG , RICE JOHN
Published: July 2009

The open innovation approach emphasizes porous knowledge boundaries between firms and upstream suppliers, but tends to ignore questions of transformative efficiency and effectiveness once the knowledge reaches the focal organization. In this paper, we test for the significance of interaction effects between open innovation strategies and absorptive capacity, finding support for the idea that effective knowledge absorption capabilities are of vital importance in the facilitation of innovation effectiveness.
IMPROVING INNOVATION CAPABILITIES OF SMALL ENTERPRISES: CLUSTER STRATEGY AS A TOOL
Authors: FORSMAN HELENA
Published: July 2009

This study focuses on innovation capabilities in small enterprises and how their development can be supported by regional strategies. The study utilizes multiple case studies. The empirical evidence is based on data from four regions in Finland. Each of them has adopted an industrial cluster approach as the basis of regional development. The study draws a common framework for assessing how regional development efforts meet the needs of innovation development in small enterprises. The findings demonstrate that most of the efforts for improving innovation capabilities of small enterprises are appropriate for innovation generation in the front-end phase. Instead, there were no significant efforts to support innovation adoption. Further, the highly conceptualised development services provided by a variety of public organizations meet the needs of large companies. However, these services match poorly with the nature of innovation development in small enterprises.
INNOVATION DIFFUSION: MOBILE TELEPHONY ADOPTION IN CHINA
Authors: LIU XIELIN , WU FENG-SHANG , CHU WEN-LIN
Published: July 2009

The rapid diffusion of mobile telephony is an important subject in diffusion studies of innovation. This study attempts to learn how mobile telephony diffuses in China, which has the most mobile telephone subscribers worldwide, in terms of the appropriate growth model and forces driving the diffusion. To identify the appropriate growth model, this study compares the fitness and forecasting ability of three conventional models — the Logistic, Bass, and Gompertz models. The determinants of the diffusion rate are then analyzed based on the most appropriate model. Empirical results, based on data for mobile telephone subscribers in China for 1986–2007, indicate that the Gompertz model performs best. Moreover, the four determinants for the diffusion rate are: number of fixed-line telephone subscribers, the low cost of mobile handsets, pre-paid service and the personal handy-phone system (PHS) service.
Bi-ComForWaRD: BIVARIATE COMPLEX FOURIER-WAVELET REGULARIZED DECONVOLUTION FOR MEDICAL IMAGING
Authors: RAO M. VENU GOPALA , VATHSAL S.
Published: June 2009

In this paper, we propose a new hybrid Bivariate Complex Fourier Wavelet Regularized Deconvolution (Bi-ComForWaRD) that is an extension to the ComForWaRD algorithm, for medical imaging. This new algorithm is a two-step process, a global blur compensation using generalized Wiener filter and followed by a denoising algorithm using local adaptive Bivariate shrinkage function. It is a low-complexity denoising algorithm using the joint statistics of the wavelet coefficients and considers the statistical dependencies between the coefficients. And also, the performance of this system will be demonstrated on both the orthogonal wavelet transform and the dual-tree complex wavelet transform (DT-CWT) and some comparisons with the best available wavelet-based image denoising results will be given in order to illustrate the effectiveness of the system.
NEURAL NETWORK-BASED INTERPOLATION AND EXTRAPOLATION OF WIND TUNNEL TEST DATA
Authors: SELVI S. THAMARAI , MAHENDRAN E. , RAMA S.
Published: June 2009

There is an increasing need to apply emerging technologies in knowledge-based management system. This proposed system captures the knowledge of experts and the knowledge acquired for designing a new systems. Wind Tunnel Test data of missiles has been taken into consideration for knowledge management. Interpolation and Extrapolation of missile test data has been attempted using neural network technique General Regression Neural Networks training algorithm. The results produced by neural network training methodologies are validated with the existing test data. The knowledge extraction using neural network is found suitable for interpolation and to some extent for extrapolation, thereby reducing the cost as well as number of test runs in Wind Tunnel Test.
DYNAMIC COMPLEXITIES OF HOLLING TYPE II FUNCTIONAL RESPONSE PREDATOR–PREY SYSTEM WITH DIGEST DELAY AND IMPULSIVE HARVESTING ON THE PREY
Authors: JIA JIANWEN , CAO HUI
Published: June 2009

In this paper, we introduce and study Holling type II functional response predator–prey system with digest delay and impulsive harvesting on the prey, which contains with periodically pulsed on the prey and time delay on the predator. We investigate the existence and global attractivity of the predator-extinction periodic solutions of the system. By using the theory on delay functional and impulsive differential equation, we obtain the sufficient condition with time delay and impulsive perturbations for the permanence of the system.
A THRESHOLD MODEL FOR CELL SURVIVAL
Authors: RANGAN A. , ARUNACHALAM V.
Published: June 2009

This paper deals with a threshold model for gene damages in a cell subject to repair. The damages and repairs are considered to be stochastic events. The status of the cell is partitioned into a number of states representing the number of proliferative gene damages it has suffered. The probability of finding the cell with a certain number of gene damages at any time and the expected number of repairs in an arbitrary interval are obtained.
MAKESPAN MINIMIZATION WITH MACHINE AVAILABILITY CONSTRAINTS
Authors: FU BIN , HUO YUMEI , ZHAO HAIRONG
Published: July 2009

We investigate the problems of scheduling n jobs to m machines with availability constraints. We consider two different models of availability constraints: the preventive model where the unavailability is due to preventive machine maintenance, and the fixed job model where the unavailability is due to a priori assignment of some of the n jobs to certain machines at certain times. In both models, the objective is to minimize the makespan. We assume that m is a constant, and if a job is interrupted by the unavailable interval, it can be resumed after the machine becomes available.

For fixed job model, we show there is an FPTAS. For the preventive model, we show that if at least one machine is always available, then the PTAS for Multiple Subset Sum problem given by Kellerer can be applied to get a PTAS; otherwise, every machine has some unavailable intervals, we show that if (m - 1) machines each of which has unavailable intervals with total length bounded by α(n) · P sum /m where P sum is the total processing time of all jobs and α(n) can be any non-negative function, we can develop a (1 + α(n) + ∊)-approximation algorithm for any constant 0 < ∊ < 1; further we show that there does not exist any polynomial time (1 + α(n) - o(1))-approximation unless P = NP.
ON CONSTRUCTION OF ALMOST-RAMANUJAN GRAPHS
Authors: SUN HE , ZHU HONG
Published: July 2009

O. Reingold et al. introduced the notion zig-zag product on two different graphs, and presented a fully explicit construction of d-regular expanders with the second largest eigenvalue O(d-1/3). In the same paper, they ask whether or not the similar technique can be used to construct expanders with the second largest eigenvalue O(d-1/2). Such graphs are called Ramanujan graphs. Recently, zig-zag product has been generalized by A. Ben-Aroya and A. Ta-Shma. Using this technique, they present a family of expanders with the second largest eigenvalue d-1/2 + o(1), what they call almost-Ramanujan graphs. However, their construction relies on local invertible functions and the dependence between the big graph and several small graphs, which makes the construction more complicated.

In this paper, we shall give a generalized theorem of zig-zag product. Specifically, the zig-zag product of one "big" graph and several "small" graphs with the same size will be formalized. By choosing the big graph and several small graphs individually, we shall present a family of fully explicitly almost-Ramanujan graphs with locally invertible function waived.
OPTIMAL SEMI-ONLINE ALGORITHM FOR SCHEDULING ON A BATCH PROCESSING MACHINE
Authors: LIU MING , XU YINFENG , CHU CHENGBIN , WANG LU
Published: July 2009

We consider two semi-online scheduling problems on a single batch (processing) machine with jobs' nondecreasing processing times and jobs' nonincreasing processing times, respectively. Our objective is to minimize the makespan. A batch processing machine can handle up to B jobs simultaneously. We study an unbounded model where B = ∞. The jobs that are processed together construct a batch, and all jobs in a batch start and complete at the same time. The processing time of a batch is given by the longest processing time of any job in the batch. Jobs arrive over time. Let pj denote the processing time of job Jj. Given job Jj and its following job Jj + 1, we assume that pj + 1 ≥ α pj, where α ≥ 1 is a constant number, for the first problem with jobs' nondecreasing processing times. For the second problem, we assume that pj + 1 ≤ α pj, where 0 < α < 1 is a constant number. We propose an optimal algorithm for both problems with a competitive ratio [Formula: see text] for the first problem and [Formula: see text] for the second problem.
ERROR-TOLERANT TRIVIAL TWO-STAGE GROUP TESTING FOR COMPLEXES USING ALMOST SEPARABLE AND ALMOST DISJUNCT MATRICES
Authors: LANG WEIWEI , WANG YUEXUAN , YU JAMES , GAO SUOGANG , WU WEILI
Published: July 2009

In this paper, we define an α-almost (k; 2e + 1)-separable matrix and an α-almostke-disjunct matrix. Using their complements, we devise algorithms for fault-tolerant trivial two-stage group tests (pooling designs) for k-complexes. We derive the expected values for the given algorithms to identify all such positive complexes.
MULTI-TERMINAL NETWORK CONNECTEDNESS ON SERIES-PARALLEL NETWORKS
Authors: FARLEY TONI R. , COLBOURN CHARLES J.
Published: July 2009

Network operation may require that a specified number k of nodes be able to communicate via paths consisting of operating edges and nodes. In an environment of node and edge failure, this leads to associated reliability measures. When the k nodes are known in advance, this has been widely studied as k-terminal reliability; when the k nodes are chosen uniformly at random, this has been studied as k-resilience. A third notion, when it suffices to have anyk nodes communicate, is related to the expected size of the largest component in the network. We generalize these three measures to the probability that given h nodes chosen in advance and i nodes chosen at random, they appear in a component of size at least k = h + i + j. As expected, for general networks, for most choices of (h, i, j) the computation is #P-complete and hence unlikely to admit a polynomial time algorithm. We develop polynomial time algorithms in the special case that the network is series-parallel, which subsume and generalize earlier methods for k-terminal reliability and k-resilience.
Fighting physics
Authors: Smith Jonathan M.
Published: June 2009

The laws of physics and the Internet's routing infrastructure affect performance in a big way.
Snapshot isolation and integrity constraints in replicated databases
Authors: Lin Yi , Kemme Bettina , Jiménez-Peris Ricardo , Patiño-Martínez Marta , Armendáriz-Iñigo José Enrique
Published: June 2009

Database replication is widely used for fault tolerance and performance. However, it requires replica control to keep data copies consistent despite updates. The traditional correctness criterion for the concurrent execution of transactions in a replicated database is 1-copy-serializability. It is based on serializability, the strongest isolation level in a nonreplicated system. In recent years, however, Snapshot Isolation (SI), a slightly weaker isolation level, has become popular in commercial database systems. There exist already several replica control protocols that provide SI in a replicated system. However, most of the correctness reasoning for these protocols has been rather informal. Additionally, most of the work so far ignores the issue of integrity constraints. In this article, we provide a formal definition of 1-copy-SI using and extending a well-established definition of SI in a nonreplicated system. Our definition considers integrity constraints in a way that conforms to the way integrity constraints are handled in commercial systems. We discuss a set of necessary and sufficient conditions for a replicated history to be producible under 1-copy-SI. This makes our formalism a convenient tool to prove the correctness of replica control algorithms.
Distributing content updates over a mobile social network
Authors: Ioannidis Stratis , Chaintreau Augustin , Massoulié Laurent
Published: June 2009

We study the dissemination of content updates, such as news or traffic information, over a mobile social network. In this application, mobile users receive content updates from their service provider. To improve coverage and increase capacity, we assume that they also share such updates, opportunistically, whenever they meet. We show that the service provider can allocate its downlink bandwidth so that it maximizes the aggregate utility over all users, i.e., the social welfare. Moreover, we specify a condition under which the system is highly scalable: even if the total bandwidth dedicated by the service provider remains fixed, the expected content age at each user grows slowly (as log(n)) with the number of users n.
Crop Yield Gaps: Their Importance, Magnitudes, and Causes
Authors: Lobell David B. , Cassman Kenneth G. , Field Christopher B.
Published: July 2009

Future trajectories of food prices, food security, and cropland expansion are closely linked to future average crop yields in the major agricultural regions of the world. Because the maximum possible yields achieved in farmers' fields might level off or even decline in many regions over the next few decades, reducing the gap between average and potential yields is critical. In most major irrigated wheat, rice, and maize systems, yields appear to be at or near 80% of yield potential, with no evidence for yields having exceeded this threshold to date. A fundamental constraint in these systems appears to be uncertainty in growing season weather; thus tools to address this uncertainty would likely reduce gaps. Otherwise, short-term prospects for yield gains in irrigated agriculture appear grim without increased yield potential. Average yields in rainfed systems are commonly 50% or less of yield potential, suggesting ample room for improvement, though estimation of yield gaps for rainfed regions is subject to more errors than for irrigated regions. Several priorities for future research are identified.
Personality and Coping
Authors: Carver Charles S. , Connor-Smith Jennifer
Published: July 2009

Personality psychology addresses views of human nature and individual differences. Biological and goal-based views of human nature provide an especially useful basis for construing coping; the five-factor model of traits adds a useful set of individual differences. Coping—responses to adversity and to the distress that results—is categorized in many ways. Meta-analyses link optimism, extraversion, conscientiousness, and openness to more engagement coping; neuroticism to more disengagement coping; and optimism, conscientiousness, and agreeableness to less disengagement coping. Relations of traits to specific coping responses reveal a more nuanced picture. Several moderators of these associations also emerge: age, stressor severity, and temporal proximity between the coping activity and the coping report. Personality and coping play both independent and interactive roles in influencing physical and mental health. Recommendations are presented for ways future research can expand on the growing understanding of how personality and coping shape adjustment to stress.
Human Development in Societal Context
Authors: Huston Aletha C. , Bentley Alison C.
Published: July 2009

Low family socioeconomic position is a net of related conditions—low income, material deprivation, single-parent family structure, low educational level, minority ethnic group membership, and immigrant status. According to ecological theory, proximal contexts experienced by children, including family, material resources, out-of-school experiences, schools, neighborhoods, and peers, are mediators of poverty effects. Developmental timing of exposure to poverty conditions and the processes by which effects occur differ for cognitive and social domains of development. Understanding how contexts combine and interact is as important as understanding their independent influences. Effects may be cumulative, but advantages in one context can also ameliorate disadvantages in others. Although research is typically based on unidirectional causal models, the relations between the developing child and the contexts he or she experiences are reciprocal and transactional. Finally, although income inequality has increased greatly, little is known about the influences of relative poverty and social inequality on human development.
Mechanisms underlying Andersen's syndrome pathology in skeletal muscle are revealed in human myotubes
Authors: Sacconi S. , Simkin D. , Arrighi N. , Chapon F. , Larroque M. M. , Vicart S. , Sternberg D. , Fontaine B. , Barhanin J. , Desnuelle C. , Bendahhou S.
Published: July 2009

Andersen's syndrome is a rare disorder that has been defined with a triad: periodic paralysis, cardiac arrhythmia, and development anomalies. Muscle weakness has been reported in two-thirds of the patients. KCNJ2 remains the only gene linked to Andersen's syndrome; this gene encodes for the α-subunit of the strong inward-rectifier K+ channel Kir2.1. Several studies have shown that Andersen's syndrome mutations lead to a loss of function of the K+ channel activity in vitro. However, ex vivo studies on isolated patient muscle tissue have not been reported. We have performed muscle biopsies of controls and patients presenting with clinically and genetically defined Andersen's syndrome disorder. Myoblasts were cultured and characterized morphologically and functionally using the whole cell patch-clamp technique. No morphological difference was observed between Andersen's syndrome and control myoblasts at each passage of the cell culture. Cellular proliferation and viability were quantified in parallel with direct cell counts and showed no difference between control and Andersen's syndrome patients. Moreover, our data show no significant difference in myoblast fusion index among Andersen's syndrome and control patients. Current recordings carried out on myotubes revealed the absence of an inwardly rectifying Ba2+-sensitive current in affected patient cells. One consequence of the Ik1 current loss in Andersen's syndrome myotubes is a shift of the resting membrane potential toward depolarizing potentials. Our data describe for the first time the functional consequences of Andersen's syndrome mutations ex vivo and provide clues to the K+ channel pathophysiology in skeletal muscle.
Control of tight junctional sealing: roles of epidermal growth factor and prostaglandin E2
Authors: Flores-Benitez D. , Rincon-Heredia R. , Razgado L. F. , Larre I. , Cereijido M. , Contreras R. G.
Published: July 2009

Epithelia can adjust the permeability of the paracellular permeation route by regulating the degree of sealing of the tight junction. This is reflected by a transepithelial electrical resistance (TER) ranging from a few tenths to several thousand ohms times square centimeters, depending on the difference in composition between the fluid in the lumen and the interstitial fluid. Although teleologically sound, such correlation requires a physiological explanation. We have previously shown that urine extracts from different animal species increase the TER of Madin-Darby canine kidney (MDCK) monolayers and that these effects are mediated by epidermal growth factor (EGF) contained in the flowing intratubular fluid that eventually reaches the urine. This increase in TER is accompanied by an enhanced expression of claudin-4 (cln-4) and a decrement of cln-2. These changes are transient, peaking at ∼16 h and returning to control values in ∼24 h. In the present work we investigated how EGF provokes this transient response, and we found that the activation of extracellular-regulated kinases 1/2 (ERK1/2) by EGF is essential to increase TER and cln-4 content, but it does not appear to participate in cln-2 downregulation. On the other hand, prostaglandin synthesis, stimulated by EGF, functions as a negative feedback, turning off the signal initiated by EGF. Thus, PGE2 blocks ERK1/2 by a mechanism that involves the Gαs protein, adenylyl cyclase as well as protein kinase A in MDCK cells. In summary, the permeability of a given segment of the nephron depends on the expression of different claudin types, which may be modulated by EGF and prostaglandins.
Involvement of a functional NADPH oxidase in neutrophils and macrophages during programmed cell clearance: implications for chronic granulomatous disease
Authors: Sanmun Duangmanee , Witasp Erika , Jitkaew Siriporn , Tyurina Yulia Y. , Kagan Valerian E. , Åhlin Anders , Palmblad Jan , Fadeel Bengt
Published: July 2009

Resolution of inflammation requires clearance of activated neutrophils by macrophages in a manner that prevents injury to adjacent tissues. Surface changes, including phosphatidylserine (PS) exposure, may target neutrophils for phagocytosis. In this study, we show that externalization of PS is defective in phorbol myristate acetate (PMA)-activated neutrophils obtained from chronic granulomatous disease (CGD) patients with mutations in components of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Moreover, activated neutrophils from CGD patients failed to undergo clearance upon cocultivation with macrophages from normal donors. In line with these results, treatment of donor neutrophils with diphenyleneiodonium (DPI), an inhibitor of NADPH oxidase, blocked PMA-induced PS oxidation and externalization and prevented their engulfment by macrophages. Furthermore, primary macrophages from CGD patients or human gp91phox-deficient PLB-985 cells differentiated into macrophage-like cells were defective for engulfment of apoptotic target cells. Pretreatment of normal macrophages with DPI also suppressed the subsequent ingestion of PS-positive target cells. Together, these data demonstrate that NADPH oxidase plays an important role in the process of macrophage disposal of target cells (programmed cell clearance). Thus we speculate that the lack of a functional NADPH oxidase results in impaired neutrophil clearance and the exaggerated inflammation that is characteristic for CGD.
PLAGL2 expression-induced lung epithelium damages at bronchiolar alveolar duct junction in emphysema: bNip3- and SP-C-associated cell death/injury activity
Authors: Yang Yih-Sheng , Yang Meng-Chun W. , Guo Yuhong , Williams Olatunji W. , Weissler Jonathan C.
Published: July 2009

Emphysema and bronchitis are major components of chronic obstructive pulmonary disease (COPD). Pleomorphic adenoma gene like-2 (PLAGL2), a zinc finger DNA-binding protein, is a transcription factor of the surfactant protein C (SP-C) promoter. Using an inducible transgenic mouse model, PLAGL2 and SP-C were ectopically expressed in lung epithelial cells of terminal bronchiole including the bronchoalveolar duct junction (BADJ), where only few cells express both genes under normal conditions. Ectopic PLAGL2 was also expressed in alveolar type II cells of induced mice. The overexpression of PLAGL2 was associated with the development of air space enlargement in the distal airways of adult mice. Defective alveolar septa and degraded airway fragments were found in the lesions of emphysematous lungs, indicating chronic airway destruction. Female mice were particularly sensitive to the effects of PLAGL2 overexpression with more dramatic emphysematous changes compared with male mice. In addition, analysis of the respiratory system mechanics in the mice indicated that the induction of PLAGL2 resulted in a significant increase in respiratory system compliance. Both TdT-mediated dUTP nick end labeling (TUNEL) and caspase-3 analyses showed that apoptotic activity was increased in epithelial cells within the emphysematous lesions as well as at the BADJ. Our results indicate that increased cell injury and/or death could be caused directly by the upregulation of PLAGL2 downstream gene, bNip3, a preapoptotic molecule that dimerizes with Bcl-2, or indirectly by the aberrant expression of SP-C-induced endoplasmic reticulum stress in epithelial cells. Finally, increased expression of PLAGL2 in alveolar epithelial cells correlated with the development of emphysema in the lung of COPD patients. In summary, our data from both animal and human studies support a novel pathogenic role of PLAGL2 in pulmonary emphysema, a critical aspect of severe COPD.
Inhibition of bilirubin metabolism induces moderate hyperbilirubinemia and attenuates ANG II-dependent hypertension in mice
Authors: Vera Trinity , Granger Joey P. , Stec David E.
Published: July 2009

Population studies indicate that moderate hyperbilirubinemia is associated with reduced incidence of cardiovascular diseases, including hypertension. Despite this correlative evidence, no studies have directly tested the hypothesis that moderate increases in plasma bilirubin levels can attenuate the development of hypertension. This hypothesis was tested by treating mice with Indinavir, a drug that competes with bilirubin for metabolism by UDP-glucuronosyltransferase 1A1 (UGT1A1). Treatment of mice with Indinavir (500 mg·kg−1·day−1, gavage) resulted in a twofold increase in plasma unconjugated bilirubin levels. Next, we determined the effect of Indinavir-induced changes in plasma bilirubin on the development of ANG II-dependent hypertension. Moderate hyperbilirubinemia was induced 3 days before the implantation of an osmotic minipump that delivered ANG II at a rate of 1 μg·kg−1·min−1. ANG II infusion increased mean arterial pressure (MAP) by 20 mmHg in control mice but by only 6 mmHg in mice treated with Indinavir ( n = 6). Similar to Indinavir treatment, direct infusion of bilirubin (37.2 mg·kg−1·day−1iv) resulted in a twofold increase in plasma bilirubin levels and also attenuated the development of ANG II-dependent hypertension. Moderate hyperbilirubinemia resulted in an increase in plasma nitrate/nitrite levels, which averaged 36 ± 2 vs. 50 ± 7 μM in ANG II vehicle vs. Indinavir-treated mice ( n = 5). Moderate hyperbilirubinemia resulted in attenuation of vascular oxidative stress as determined by dihydroethidium staining of aortic segments. These results indicate that moderate hyperbilirubinemia prevents ANG II-dependent hypertension by a mechanism that may involve decreases in vascular oxidative stress.
Expression and phosphorylation of the Na+-Cl− cotransporter NCC in vivo is regulated by dietary salt, potassium, and SGK1
Authors: Vallon Volker , Schroth Jana , Lang Florian , Kuhl Dietmar , Uchida Shinichi
Published: July 2009

The Na-Cl cotransporter NCC is expressed in the distal convoluted tubule, activated by phosphorylation, and has been implicated in renal NaCl and K+ homeostasis. The serum and glucocorticoid inducible kinase 1 (SGK1) contributes to renal NaCl retention and K+ excretion, at least in part, by stimulating the epithelial Na+ channel and Na+-K+-ATPase in the downstream segments of aldosterone-sensitive Na+/K+ exchange. In this study we confirmed in wild-type mice (WT) that dietary NaCl restriction increases renal NCC expression and its phosphorylation at Thr53, Thr58, and Ser71, respectively. This response, however, was attenuated in mice lacking SGK1 ( Sgk1−/−), which may contribute to impaired NaCl retention in those mice. Total renal NCC expression and phosphorylation at Thr53, Thr58, and Ser71 in WT were greater under low- compared with high-K+ diet. This finding is consistent with a regulation of NCC to modulate Na+ delivery to downstream segments of Na+/K+ exchange, thereby modulating K+ excretion. Dietary K+-dependent variation in renal expression of total NCC and phosphorylated NCC were not attenuated in Sgk1−/− mice. In fact, high-K+ diet-induced NCC suppression was enhanced in Sgk1−/− mice. The hyperkalemia induced in Sgk1−/− mice by a high-K+ diet may have augmented NCC suppression, thereby increasing Na+ delivery and facilitating K+ excretion in downstream segments of impaired Na+/K+ exchange. In summary, changes in NaCl and K+ intake altered NCC expression and phosphorylation, an observation consistent with a role of NCC in NaCl and K+ homeostasis. The two maneuvers dissociated plasma aldosterone levels from NCC expression and phosphorylation, implicating additional regulators. Regulation of NCC expression and phosphorylation by dietary NaCl restriction appears to involve SGK1.
Atrial natriuretic peptide and nitric oxide signaling antagonizes vasopressin-mediated water permeability in inner medullary collecting duct cells
Authors: Klokkers Jens , Langehanenberg Patrik , Kemper Björn , Kosmeier Sebastian , von Bally Gert , Riethmüller Christoph , Wunder Frank , Sindic Aleksandra , Pavenstädt Hermann , Schlatter Eberhard , Edemir Bayram
Published: July 2009

AVP and atrial natriuretic peptide (ANP) have opposite effects in the kidney. AVP induces antidiuresis by insertion of aquaporin-2 (AQP2) water channels into the plasma membrane of collecting duct principal cells. ANP acts as a diuretic factor. An ANP- and nitric oxide (NO)/soluble guanylate cyclase (sGC)-induced insertion of AQP2 into the plasma membrane is reported from different models. However, functional data on the insertion of AQP2 is missing. We used primary cultured inner medullary collecting duct (IMCD) cells and digital holographic microscopy, calcein-quenching measurements, and immunofluorescence and Western blotting to analyze the effects of ANP and NO donors on AQP2 phosphorylation, membrane expression, and water permeability. While AVP led to acceleration in osmotically induced swelling, ANP had no effect. However, in AVP-pretreated cells ANP significantly decreased the kinetics of cell swelling. This effect was mimicked by 8-bromo-cGMP and blunted by PKG inhibition. Stimulation of the NO/sGC pathway or direct activation of sGC with BAY 58-2667 had similar effects to ANP. In cells treated with AVP, AQP2 was predominantly localized in the plasma membrane, and after additional incubation with ANP AQP2 was mostly localized in the cytosol, indicating an increased retrieval of AQP2 from the plasma membrane by ANP. Western blot analysis showed that ANP was able to reduce AVP-induced phosphorylation of AQP2 at position S256. In conclusion, we show that the diuretic action of ANP or NO in the IMCD involves a decreased localization of AQP2 in the plasma membrane which is mediated by cGMP and PKG.