bluuebunny/crossref_metadata_2025 huggingface dataset:
A DYNAMICAL SYSTEM APPROACH TO THE GBIG COSMOLOGY
Authors: NOZARI KOUROSH , KIANI F.
Published: May 2011

We study the phase space of an extension of the normal DGP cosmology with a cosmological constant on the brane and curvature effect that is incorporated via the Gauss–Bonnet term in the bulk action. We study late-time cosmological dynamics of this scenario within a dynamical system approach. We show that the stable solution of the cosmological dynamics in this model is a de Sitter phase.
GENERALIZED GRAVITY IN CLIFFORD SPACES, VACUUM ENERGY AND GRAND UNIFICATION
Authors: CASTRO CARLOS
Published: May 2011

Polyvector-valued gauge field theories in Clifford spaces are used to construct a novel Cl (3, 2) gauge theory of gravity that furnishes modified curvature and torsion tensors leading to important modifications of the standard gravitational action with a cosmological constant. Vacuum solutions exist which allow a cancelation of the contributions of a very large cosmological constant term and the extra terms present in the modified field equations. Generalized gravitational actions in Clifford-spaces are provided and some of their physical implications are discussed. It is shown how the 16 fermions and their masses in each family can be accommodated within a Cl (4) gauge field theory. In particular, the Higgs fields admit a natural Clifford-space interpretation that differs from the one in the Chamseddine–Connes spectral action model of non-commutative geometry. We finalize with a discussion on the relationship with the Pati–Salam color-flavor model group SU (4)C × SU (4)F and its symmetry breaking patterns. An Appendix is included with useful Clifford algebraic relations.
A GEOMETRIC SETTING FOR SYSTEMS OF ORDINARY DIFFERENTIAL EQUATIONS
Authors: BUCATARU IOAN , CONSTANTINESCU OANA , DAHL MATIAS F.
Published: May 2011

To a system of second-order ordinary differential equations one can assign a canonical nonlinear connection that describes the geometry of the system. In this paper, we develop a geometric setting that also allows us to assign a canonical nonlinear connection to a system of higher-order ordinary differential equations (HODE). For this nonlinear connection we develop its geometry, and explicitly compute all curvature components of the corresponding Jacobi endomorphism. Using these curvature components we derive a Jacobi equation that describes the behavior of nearby geodesics to a HODE. We motivate the applicability of this nonlinear connection using examples from the equivalence problem, the inverse problem of the calculus of variations, and biharmonicity. For example, using components of the Jacobi endomorphism we express two Wuenschmann-type invariants that appear in the study of scalar third- or fourth-order ordinary differential equations.
Robot algorithms for localization of multiple emission sources
Authors: Mcgill Kathleen , Taylor Stephen
Published: May 2011

The problem of time-varying, multisource localization using robotic swarms has received relatively little attention when compared to single-source localization. It involves distinct challenges regarding how to partition the robots during search to ensure that all sources are located in minimal time, how to avoid obstacles and other robots, and how to proceed after each source is found. Unfortunately, no common set of validation problems and reference algorithms has evolved, and there are no general theoretical foundations that guarantee progress, convergence, and termination. This article surveys the current multisource literature from the viewpoint of these central questions.
Programming wireless sensor networks
Authors: Mottola Luca , Picco Gian Pietro
Published: May 2011

Wireless sensor networks (WSNs) are attracting great interest in a number of application domains concerned with monitoring and control of physical phenomena, as they enable dense and untethered deployments at low cost and with unprecedented flexibility.

However, application development is still one of the main hurdles to a wide adoption of WSN technology. In current real-world WSN deployments, programming is typically carried out very close to the operating system, therefore requiring the programmer to focus on low-level system issues. This not only distracts the programmer from the application logic, but also requires a technical background rarely found among application domain experts. The need for appropriate high-level programming abstractions, capable of simplifying the programming chore without sacrificing efficiency, has long been recognized, and several solutions have hitherto been proposed, which differ along many dimensions.

In this article, we survey the state of the art in programming approaches for WSNs. We begin by presenting a taxonomy of WSN applications, to identify the fundamental requirements programming platforms must deal with. Then, we introduce a taxonomy of WSN programming approaches that captures the fundamental differences among existing solutions, and constitutes the core contribution of this article. Our presentation style relies on concrete examples and code snippets taken from programming platforms representative of the taxonomy dimensions being discussed. We use the taxonomy to provide an exhaustive classification of existing approaches. Moreover, we also map existing approaches back to the application requirements, therefore providing not only a complete view of the state of the art, but also useful insights for selecting the programming abstraction most appropriate to the application at hand.
The state of the art in end-user software engineering
Authors: Ko Amy J. , Abraham Robin , Beckwith Laura , Blackwell Alan , Burnett Margaret , Erwig Martin , Scaffidi Chris , Lawrance Joseph , Lieberman Henry , Myers Brad , Rosson Mary Beth , Rothermel Gregg , Shaw Mary , Wiedenbeck Susan
Published: May 2011

Most programs today are written not by professional software developers, but by people with expertise in other domains working towards goals for which they need computational support. For example, a teacher might write a grading spreadsheet to save time grading, or an interaction designer might use an interface builder to test some user interface design ideas. Although these end-user programmers may not have the same goals as professional developers, they do face many of the same software engineering challenges, including understanding their requirements, as well as making decisions about design, reuse, integration, testing, and debugging. This article summarizes and classifies research on these activities, defining the area of End-User Software Engineering (EUSE) and related terminology. The article then discusses empirical research about end-user software engineering activities and the technologies designed to support them. The article also addresses several crosscutting issues in the design of EUSE tools, including the roles of risk, reward, and domain complexity, and self-efficacy in the design of EUSE tools and the potential of educating users about software engineering principles.
A survey of comparison-based system-level diagnosis
Authors: Duarte Elias P. , Ziwich Roverli P. , Albini Luiz C.P.
Published: May 2011

The growing complexity and dependability requirements of hardware, software, and networks demand efficient techniques for discovering disruptive behavior in those systems. Comparison-based diagnosis is a realistic approach to detect faulty units based on the outputs of tasks executed by system units. This survey integrates the vast amount of research efforts that have been produced in this field, from the earliest theoretical models to new promising applications. Key results also include the quantitative evaluation of a relevant reliability metric—the diagnosability—of several popular interconnection network topologies. Relevant diagnosis algorithms are also described. The survey aims at clarifying and uncovering the potential of this technology, which can be applied to improve the dependability of diverse complex computer systems.
Interactive editing of massive imagery made simple
Authors: Summa Brian , Scorzelli Giorgio , Jiang Ming , Bremer Peer-Timo , Pascucci Valerio
Published: May 2011

This article presents a simple framework for progressive processing of high-resolution images with minimal resources. We demonstrate this framework's effectiveness by implementing an adaptive, multi-resolution solver for gradient-based image processing that, for the first time, is capable of handling gigapixel imagery in real time. With our system, artists can use commodity hardware to interactively edit massive imagery and apply complex operators, such as seamless cloning, panorama stitching, and tone mapping.

We introduce a progressive Poisson solver that processes images in a purely coarse-to-fine manner, providing near instantaneous global approximations for interactive display (see Figure 1). We also allow for data-driven adaptive refinements to locally emulate the effects of a global solution. These techniques, combined with a fast, cache-friendly data access mechanism, allow the user to interactively explore and edit massive imagery, with the illusion of having a full solution at hand. In particular, we demonstrate the interactive modification of gigapixel panoramas that previously required extensive offline processing. Even with massive satellite images surpassing a hundred gigapixels in size, we enable repeated interactive editing in a dynamically changing environment. Images at these scales are significantly beyond the purview of previous methods yet are processed interactively using our techniques. Finally our system provides a robust and scalable out-of-core solver that consistently offers high-quality solutions while maintaining strict control over system resources.
Metropolis procedural modeling
Authors: Talton Jerry O. , Lou Yu , Lesser Steve , Duke Jared , Měch Radomír , Koltun Vladlen
Published: May 2011

Procedural representations provide powerful means for generating complex geometric structures. They are also notoriously difficult to control. In this article, we present an algorithm for controlling grammar-based procedural models. Given a grammar and a high-level specification of the desired production, the algorithm computes a production from the grammar that conforms to the specification. This production is generated by optimizing over the space of possible productions from the grammar. The algorithm supports specifications of many forms, including geometric shapes and analytical objectives. We demonstrate the algorithm on procedural models of trees, cities, buildings, and Mondrian paintings.
Image and video upscaling from local self-examples
Authors: Freedman Gilad , Fattal Raanan
Published: May 2011

We propose a new high-quality and efficient single-image upscaling technique that extends existing example-based super-resolution frameworks. In our approach we do not rely on an external example database or use the whole input image as a source for example patches. Instead, we follow alocal self-similarityassumption on natural images and extract patches from extremely localized regions in the input image. This allows us to reduce considerably the nearest-patch search time without compromising quality in most images. Tests, that we perform and report, show that the local self-similarity assumption holds better for small scaling factors where there are more example patches of greater relevance. We implement these small scalings using dedicated novel nondyadic filter banks, that we derive based on principles that model the upscaling process. Moreover, the new filters are nearly biorthogonal and hence produce high-resolution images that are highly consistent with the input image without solving implicit back-projection equations. The local and explicit nature of our algorithm makes it simple, efficient, and allows a trivial parallel implementation on a GPU. We demonstrate the new method ability to produce high-quality resolution enhancement, its application to video sequences with no algorithmic modification, and its efficiency to perform real-time enhancement of low-resolution video standard into recent high-definition formats.
A hybrid hardware--software technique to improve reliability in embedded processors
Authors: Ragel Roshan G. , Parameswaran Sri
Published: May 2011

Numerous methods have been described in research literature with methods to improve reliability of processors by the use of control-flow checking. High performance and code-size penalties cripple the proposed software approaches, while hardware approaches are not scalable and are thus rarely implemented in real embedded systems. In this article, we show that by including control-flow checking as an issue to be considered when designing as embedded processor, we are able to reduce overheads considerably and still provide a scalable solution to this problem. The technique described in this article includes architectural improvements to the processor and binary rewriting of the application. Architectural refinement incorporates additional instructions to the instruction set architecture, while the binary rewriting utilizes these additional instructions into the program flow. Applications from an embedded systems benchmark suite have been used to test and evaluate the system. Our approach increased code size by only 5.55% to 13.5% and reduced performance by just 0.54% to 2.83% for eight different industry standard benchmarks. The additional hardware overhead due to the additional instruction in the design is just 2.70%. In contrast, the state-of-the-art software-only approach required 50% to 150% additional code, and reduced performance by 53.5% to 99.5% when monitoring was inserted. Fault injection analysis demonstrates that our solution is capable of capturing and recovering from all the injected control-flow errors, while the software-only approach detected 87% of the injected control-flow errors.
Closed-loop--based self-adaptive Hardware/Software-Embedded systems
Authors: Diguet Jean-Philippe , Eustache Yvan , Gogniat Guy
Published: May 2011

This article presents our methodology for implementing self-adaptivness within an OS-based and reconfigurable embedded system according to objectives such as quality of service, performance, or power consumption. We detail our approach to separate application-specific decisions and hardware/software-implementation decisions at system level. The former are related to the efficiency control of applications and based on the knowledge of application engineers. The latter are generic and address the choice between various hardware and software implementations according to user objectives. The decision management is implemented as an adaptive closed-loop model. We describe how each design step may be implemented and especially how we solved the issue of stability. Finally, we present a video-tracking application implemented on a FPGA to demonstrate the effectiveness of our solution, results are given for a system built around a NIOS soft-core with μCOS II RTOS and new services for managing hardware and software tasks transparently.
Fine-grained DVFS using on-chip regulators
Authors: Eyerman Stijn , Eeckhout Lieven
Published: May 2011

Limit studies on Dynamic Voltage and Frequency Scaling (DVFS) provide apparently contradictory conclusions. On the one hand early limit studies report that DVFS is effective at large timescales (on the order of million(s) of cycles) with large scaling overheads (on the order of tens of microseconds), and they conclude that there is no need for small overhead DVFS at small timescales. Recent work on the other hand—motivated by the surge of on-chip voltage regulator research—explores the potential of fine-grained DVFS and reports substantial energy savings at timescales of hundreds of cycles (while assuming no scaling overhead).

This article unifies these apparently contradictory conclusions through a DVFS limit study that simultaneously explores timescale and scaling speed. We find that coarse-grained DVFS is unaffected by timescale and scaling speed, however, fine-grained DVFS may lead to substantial energy savings for memory-intensive workloads. Inspired by these insights, we subsequently propose a fine-grained microarchitecture-driven DVFS mechanism that scales down voltage and frequency upon individual off-chip memory accesses using on-chip regulators. Fine-grained DVFS reduces energy consumption by 12% on average and up to 23% over a collection of memory-intensive workloads for an aggressively clock-gated processor, while incurring an average 0.08% performance degradation (and at most 0.14%). We also demonstrate that the proposed fine-grained DVFS mechanism is orthogonal to existing coarse-grained DVFS policies, and further reduces energy by 6% on average and up to 11% for memory-intensive applications with limited performance impact (at most 0.7%).
Exploring the effects of on-chip thermal variation on high-performance multicore architectures
Authors: Cher Chen-Yong , Kursun Eren
Published: May 2011

Inherent temperature variation among cores in a multicore architecture can be caused by a number of factors including process variation, cooling and packaging imperfections, and even placement of the chip in the module. Current dynamic thermal management techniques assume identical heating profiles for homogeneous multicore architectures. Our experimental results indicate that inherent thermal variation is very common in existing multicores. While most multicore chips accommodate multiple thermal sensors, the dynamic power/thermal management schemes are oblivious of the inherent heating tendencies. Hence, in the case of variation, the chip faces repetitive hotspots running on such cores. In this article, we propose a technique that leverages the on-chip sensor infrastructure as well as the capabilities of power/thermal management to effectively reduce the heating and minimize local hotspots. This technique can be used in existing multicore chips as long as the thermal sensor data can be made transparent to the power/thermal management at the software layer. According to our experimental analysis on test-chips, 5°C peak temperature reduction can be achieved with no performance degradation, hence the inherent energy efficiency of the chip can be improved without any performance or cost penalty.
Adaptive timekeeping replacement
Authors: Wu Carole-Jean , Martonosi Margaret
Published: May 2011

In chip multiprocessors (CMPs), several high-performance cores typically compete for capacity in a shared last-level cache. This causes degraded and unpredictable memory performance for multiprogrammed and parallel workloads. In response, recent schemes apportion cache bandwidth and capacity in ways that offer better aggregate performance for the workloads. These schemes, however, focus primarily on relatively coarse-grained capacity management without concern for operating system process priority levels.

In this work, we explore capacity management approaches that are both temporally and spatially more fine-grained than prior work. We also consider operating system priority levels as part of capacity management. We propose a capacity management mechanism based on timekeeping techniques that track the time interval since the last access to cached data. This Adaptive Timekeeping Replacement (ATR) scheme maintains aggregate cache occupancies that reflect the priority and footprint of each application. The key novelties of our work are (1) ATR offers a complete cache capacity management framework taking into account application priorities and memory characteristics, and (2) ATR's fine-grained cache capacity control is demonstrated to be effective and important in improving the performance of parallel workloads in addition to sequential ones.

We evaluate our ideas using a full-system simulator and multiprogrammed workloads of both sequential and parallel applications. This is the first detailed study of shared cache capacity management considering thread behaviors in parallel applications. ATR outperforms an unmanaged system by as much as 1.63X and by an average of 1.19X. ATR's fine-grained temporal control is particularly important for parallel applications, which are expected to be increasingly prevalent in years to come.
Sketching interactive systems with sketchify
Authors: Obrenovic Željko , Martens Jean-Bernard
Published: May 2011

Recent discussions in the interaction design community have called attention to sketching as an omnipresent element of any disciplined activity of design, and have pointed out that sketching should be extended beyond the simple creation of a pencil trace on paper. More specifically, the need to deal with all attributes of a user experience, especially the timing, phrasing, and feel of the interaction, has been identified. In this article, we propose extending the concept of sketching with a pencil on paper to the more generic concept of fluent exploration of interactive materials. We define interactive materials as any piece of software or hardware that represents or simulates a part of the interactive user experience, such as input from sensors, output in the form of sound, video, or image, or interaction with Web services or specialized programs. We have implemented the proposed concept within Sketchify, a tool for sketching user interfaces. Sketchify gives designers the freedom to manipulate interactive materials by combining elements of traditional freehand sketching with functional extensions and end-user programming tools, such as spreadsheets and scripting. We have evaluated Sketchify in the education of interaction designers, identifying both successful aspects and aspects that need further improvements.
Solving systems of rational equations through strategy iteration
Authors: Gawlitza Thomas Martin , Seidl Helmut
Published: May 2011

We present practical algorithms for computing exact least solutions of equation systems over the reals with addition, multiplication by positive constants, minimum and maximum. The algorithms are based on strategy iteration. Our algorithms can, for instance, be used for the analysis of recursive stochastic games. In the present article we apply our techniques for computing abstract least fixpoint semantics of affine programs over the relational template polyhedra domain. In particular, we thus obtain practical algorithms for computing abstract least fixpoint semantics over the abstract domains of intervals, zones, and octagons.
Diagnostic Evaluation of Information Retrieval Models
Authors: Fang Hui , Tao Tao , Zhai Chengxiang
Published: May 2011

Developing effective retrieval models is a long-standing central challenge in information retrieval research. In order to develop more effective models, it is necessary to understand the deficiencies of the current retrieval models and the relative strengths of each of them. In this article, we propose a general methodology to
analytically
and
experimentally
diagnose the weaknesses of a retrieval function, which provides guidance on how to further improve its performance. Our methodology is motivated by the empirical observation that good retrieval performance is closely related to the use of various retrieval heuristics. We connect the weaknesses and strengths of a retrieval function with its implementations of these retrieval heuristics, and propose two strategies to check how well a retrieval function implements the desired retrieval heuristics. The first strategy is to formalize heuristics as constraints, and use constraint analysis to analytically check the implementation of retrieval heuristics. The second strategy is to define a set of relevance-preserving perturbations and perform diagnostic tests to empirically evaluate how well a retrieval function implements retrieval heuristics. Experiments show that both strategies are effective to identify the potential problems in implementations of the retrieval heuristics. The performance of retrieval functions can be improved after we fix these problems.
Conversational alignment
Authors: Henderson Austin , Harris Jed
Published: May 2011

Models help bridge the gap between observing and making---especially when systems are involved (as in designing for interaction, service, and evolution). This forum introduces new models, links them to existing models, and describes their history and why they matter.
Adipokines identified as new downstream targets for adiponectin: lessons from adiponectin-overexpressing or -deficient mice
Authors: Ge Qian , Ryken Laurence , Noel Laurence , Maury Eléonore , Brichard Sonia M.
Published: May 2011

Adipokines play a central role in the pathogenesis of the metabolic syndrome. Among them, adiponectin (ApN), a master regulator of immune and fuel homeostasis, is decreased. Identifying downstream adipokines targeted by ApN may help in deciphering this syndrome. We have generated transgenic mice, allowing persistent and moderate overexpression of ApN (ApN-Overex) specifically in white adipose tissue (AT). We took advantage of this model to unravel the adipokine secretion profile triggered by ApN. AT was fractionated into adipocytes and stromal-vascular cells (SVC), which were cultured for 8 h. Profiling of secretory products by antibody arrays and subsequent ELISAs showed that the secretion of three proinflammatory factors (IL-17B, IL-21, TNFα) and three hematopoietic growth factors [GF; thrombopoietin and granulocyte (macrophage) colony-stimulating-factors] was reduced in adipocytes of ApN-Overex mice compared with wild-type mice. In the SVC of these mice, besides the hematopoietic GFs, the secretion of another GF (vascular endothelial GF receptor 1), two chemokines (RANTES and ICAM-1), and two proinflammatory factors (IL-6 and IL-12p70) was reduced as well. Only one cytokine, IL-1 receptor 4, was oversecreted by SVC of ApN-Overex mice, which may exhibit anti-inflammatory properties. Most of these changes in secretion were due to corresponding changes in mRNAs. A reverse profile of adipokine expression was observed in ApN-KO mice. In conclusion, ApN regulates in vivo the secretion of downstream adipokines, thereby inducing a shift of the immune balance in both adipocytes and SVC toward a less inflammatory phenotype. These downstream adipokines may be new therapeutic targets for the management of the metabolic syndrome.
Systolic dysfunction in cardiac-specific ligand-inducible MerCreMer transgenic mice
Authors: Hall Michael E. , Smith Grant , Hall John E. , Stec David E.
Published: May 2011

The Cre-loxP system is a useful tool to study the physiological effects of gene knockout in the heart. One limitation with using this system in the heart is the toxic effect of chronic expression of the Cre recombinase. To circumvent this limitation, a widely used inducible cardiac-specific model, Myh6-MerCreMer (Cre), using tamoxifen (TAM) to activate Cre has been developed. The current study examined cardiac function in Cre-positive C57B/J6 mice exposed to one, three, or five daily doses of a 40 mg/kg TAM to induce Cre activity specifically in the heart. Echocardiography demonstrated no statistically significant differences in systolic function (SF) at baseline as assessed by fractional shortening. In mice exposed to five injections, a significant fall in all determinants of SF was observed 6 days after TAM was initiated. However, SF returned to baseline levels 10 days after TAM initiation although the hearts exhibited significant hypertrophy. Heart weight-to-tibia length ratios were 73 ± 3, 78.5 ± 6, and 87.6 ± 9 mg/cm for one, three, and five TAM injections, respectively. TAM had no effect on cardiac function or hypertrophy in Cre-negative mice. Cre-positive mice receiving five TAM injections had significant reductions in cardiac mitochondrial ATP and significant reductions in the expression of proteins important for the regulation of cardiac oxidative phosphorylation including peroxisome proliferator-activated receptor-γ coactivator-1α and pyruvate dehydrogenase kinase-4. Thus inducible cardiac-specific activation of Cre recombinase caused a transient decline in SF that was dependent on the number of TAM doses and associated with significant hypertrophy and alterations in mitochondrial ATP and important proteins involved in the regulation of cardiac oxidative phosphorylation.
Baroreceptor unloading in postural tachycardia syndrome augments peripheral chemoreceptor sensitivity and decreases central chemoreceptor sensitivity
Authors: Taneja Indu , Medow Marvin S. , Clarke Debbie A. , Ocon Anthony J. , Stewart Julian M.
Published: May 2011

While orthostatic tachycardia is the hallmark of postural tachycardia syndrome (POTS), orthostasis also initiates increased minute ventilation (V̇e) and decreased end-tidal CO2 in many patients. We hypothesized that chemoreflex sensitivity would be increased in patients with POTS. We therefore measured chemoreceptor sensitivity in 20 POTS (16 women and 4 men) and 14 healthy controls (10 women and 4 men), 16–35 yr old by exposing them to eucapneic hyperoxia (30% O2), eucapneic hypoxia (10% O2), and hypercapnic hyperoxia (30% O2 + 5% CO2) while supine and during 70° head-upright tilt. Heart rate, mean arterial pressure, O2 saturation, end-tidal CO2, and V̇e were measured. Peripheral chemoreflex sensitivity was calculated as the difference in V̇e during hypoxia compared with room air divided by the change in O2 saturation. Central chemoreflex sensitivity was determined by the difference in V̇e during hypercapnia divided by the change in CO2. POTS subjects had an increased peripheral chemoreflex sensitivity (in l·min−1·%oxygen−1) in response to hypoxia (0.42 ± 0.38 vs. 0.19 ± 0.17) but a decreased central chemoreflex sensitivity (l·min−1·Torr−1) CO2 response (0.49 ± 0.38 vs. 1.04 ± 0.18) compared with controls. CO2 sensitivity was also reduced in POTS subjects when supine. POTS patients are markedly sensitized to hypoxia when upright but desensitized to CO2 while upright or supine. The interactions between orthostatic baroreflex unloading and altered chemoreflex sensitivities may explain the hyperventilation in POTS patients.
Urinary Prothrombin Fragment 1+2 in relation to Development of Non-Symptomatic and Symptomatic Venous Thromboembolic Events following Total Knee Replacement
Authors: Borris Lars C. , Breindahl Morten , Lassen Michael R. , Pap Ákos F.
Published: May 2011

Prothrombin fragment 1+2 is excreted in urine (uF1+2) as a result ofin vivothrombin generation and can be a marker of coagulation status after an operative procedure. This study compared uF1+2 levels in patients with symptomatic and non-symptomatic venous thromboembolism (VTE) after total knee replacement (TKR) and in event-free sex- and age-matched controls. Significantly higher median uF1+2 levels were seen in the VTE patients on days 1, 3, and the day of venography (mostly day 7) after TKR compared with controls. The uF1+2 levels tended to be high in some patients with symptomatic VTE; however, the discriminatory efficacy of the test could not be evaluated. In conclusion, this study showed that patients with VTE tend to have significantly higher uF1+2 levels compared with patients without events between days 1 and 7 after TKR surgery. Measurement of uF1+2 could provide a simple, non-invasive clinical test to identify patients at risk of VTE.
Pain in Amyotrophic Lateral Sclerosis: A Neglected Aspect of Disease
Authors: Handy Chalonda R. , Krudy Christina , Boulis Nicholas , Federici Thais
Published: May 2011

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder marked by progressive loss of motor neurons, muscle wasting, and respiratory dysfunction. With disease progression, secondary symptoms arise creating new problematic conditions for ALS patients. Amongst these is pain. Although not a primary consequence of disease, pain occurs in a substantial number of individuals. Yet, studies investigating its pathomechanistic properties in the ALS patient are lacking. Therefore, more exploratory efforts into its scope, severity, impact, and treatment should be initiated. Several studies investigating the use of Clostridial neurotoxins for the reduction of pain in ALS patients suggest the potential for a neural specific approach involving focal drug delivery. Gene therapy represents a way to accomplish this. Therefore, the use of viral vectors to express transgenes that modulate the nociceptive cascade could prove to be an effective way to achieve meaningful benefit in conditions of pain in ALS.
The Discovery of Novel Selective D1 Dopaminergic Agonists: A-68930, A-77636, A-86929, and ABT-413
Authors: Martin Yvonne Connolly
Published: May 2011

The novel selective D1 dopaminergic full agonists A-68930, A-77636 were discovered by the synthesis of molecules to probe the bioactive conformation of the partial agonist SKF-38393, by the use of this information to add D1 affinity and selectivity to a screening hit, and by traditional medicinal chemistry exploration of structure-activity relationships. The subsequent design of A-86929 and ABT-413 capitalized on these results, recently disclosed agonists, and traditional medicinal chemistry.
Role of Natural Killer and Dendritic Cell Crosstalk in Immunomodulation by Commensal Bacteria Probiotics
Authors: Rizzello Valeria , Bonaccorsi Irene , Dongarrà Maria Luisa , Fink Lisbeth Nielsen , Ferlazzo Guido
Published: May 2011

A cooperative dialogue between natural killer (NK) cells and dendritic cells (DCs) has been elucidated in the last years. They help each other to acquire their complete functions, both in the periphery and in the secondary lymphoid organs. Thus, NK cells′ activation by dendritic cells allows the killing of transformed or infected cells in the periphery but may also be important for the generation of adaptive immunity. Indeed, it has been shown that NK cells may play a key role in polarizing a Th1 response upon interaction with DCs exposed to microbial products. This regulatory role of DC/NK cross‐talk is of particular importance at mucosal surfaces such as the intestine, where the immune system exists in intimate association with commensal bacteria such as lactic acid bacteria (LAB). We here review NK/DC interactions in the presence of gut‐derived commensal bacteria and their role in bacterial strain‐dependent immunomodulatory effects. We particularly aim to highlight the ability of distinct species of commensal bacterial probiotics to differently affect the outcome of DC/NK cross‐talk and consequently to differently influence the polarization of the adaptive immune response.
Spectral Line Broadening in Dense Plasmas
Authors: Omar Banaz
Published: May 2011

Spectral line broadening is calculated based on a microscopic quantum statistical approach. By using thermodynamic Green's function, plasma correlation effect, electrostatic and dynamic screening, and perturber-radiator interaction are taken into account. Ions are treated in quasistatic approximation due to Stark effect. The line broadening
for 6678 Å (21P-31D) and
5016 Å (21S-31P) transitions of neutral helium is calculated in the electron density range ne=(0.25–50)×1022 m-3 and temperature range T=(0.5–4)×104 K, and the density and temperature dependence of the line width are investigated. A good agreement is shown by comparing the calculated values with the existing experimental and theoretical data.
Stability of the NLS Equation with Viscosity Effect
Authors: Karjanto N. , Tiong K. M.
Published: May 2011

A nonlinear Schrödinger (NLS) equation with an effect of viscosity is derived from a Korteweg‐de Vries (KdV) equation modified with viscosity using the method of multiple time scale. It is well known that the plane‐wave solution
of the NLS equation exhibits modulational instability phenomenon. In this paper, the
modulational instability of the plane‐wave solution of the NLS equation modified with
viscosity is investigated. The corresponding modulational dispersion relation is expressed
as a quadratic equation with complex‐valued coefficients. By restricting the modulational
wavenumber into the case of narrow‐banded spectra, it is observed that a type of dissipation,
in this case the effect of viscosity, stabilizes the modulational instability, as confirmed by earlier findings.
Effects of Vitamin D Plus Calcium Supplements on Pharmacokinetics of Isoflavones in Thai Postmenopausal Women
Authors: Teekachunhatean Supanimit , Pongnad Paveena , Rojanasthein Noppamas , Manorot Maleeya , Sangdee Chaichan
Published: May 2011

The objective of this study was to determine the effects of vitamin D3 plus calcium supplements (D3‐calcium) on pharmacokinetics of isoflavones in Thai postmenopausal women. This study was an open‐labeled, randomized three‐phase crossover study. Twelve healthy subjects were randomized to receive one of the following regimens: (a) a single dose of isoflavones, (b) a single dose of isoflavones, and D3‐calcium, or (c) continuous D3‐calcium for 7 days followed by a single dose of isoflavones on the 8th day. After a washout period, subjects were switched to receive the 2 remaining regimens according to their randomized sequences. Blood samples were collected before dose and at specific time points until 32 hours after isoflavone administration. Plasma was treated with β‐glucuronidase/sulfatase to hydrolyze glucuronide and sulfate conjugates of daidzein and genistein. Plasma concentrations of daidzein and genistein were determined by high performance liquid chromatography. The estimated pharmacokinetic parameters of isoflavones were time to maximal plasma concentration (Tmax), maximal plasma concentration (Cmax), half‐life (t1/2) and area under the plasma concentration‐time curve (AUC). Tmax of daidzein and genistein after regimen B was significantly longer than that of regimen A. Other pharmacokinetic parameters of daidzein and genistein obtained following the three regimens were not significantly different.
TNFα Accelerates Monocyte to Endothelial Transdifferentiation in Tumors by the Induction of Integrin α5 Expression and Adhesion to Fibronectin
Authors: Li Bin , Pozzi Ambra , Young Pampee P.
Published: May 2011

Tumor-associated myeloid cells are believed to promote tumor development by stimulating tumor growth, angiogenesis, invasion, and metastasis. Tumor-associated myeloid cells that coexpress endothelial and myeloid markers represent a proangiogenic subpopulation known as vascular leukocytes. Recently, we and others had shown that tumor-derived TNFα promotes local tumor growth and vascularity. Our data suggested that tumor growth is in part due to TNFα-mediated increased numbers of tumor-associated vascular leukocytes (i.e., myeloid–endothelial biphenotypic cells). The work detailed herein explored the mechanism by which TNFα mediates endothelial differentiation of myeloid cells. Our studies showed that fibronectin is a robust facilitator of endothelial differentiation of blood mononuclear cells in vitro. We have found that TNFα treatment of monocytes significantly increased expression of α5β1 integrin, a major fibronectin receptor enriched on endothelial cells, leading to a consequent fourfold increase in fibronectin adhesion. Furthermore, TNFα-treated monocytes upregulated expression of endothelial markers, flk-1(VEGFR2/KDR) and VE-cadherin. Integrin α5 subunit inhibitory antibodies blocked adhesion to fibronectin as well as consequent upregulation of flk-1 and VE-cadherin transcripts, implying a role for outside-in signaling by the α5β1 integrin after binding fibronectin. Finally, treatment of mouse tumors with anti-α5 antibodies reduced accumulation of tumor vascular leukocytes in vivo. Our studies suggest that tumor cell–derived TNFα constitutes a tumor microenvironment signal that promotes differentiation of tumor-associated monocytes toward a proangiogenic/provasculogenic myeloid–endothelial phenotype via upregulation of the fibronectin receptor α5β1. Mol Cancer Res; 9(6); 702–11. ©2011 AACR.
Vein of Galen Aneurysms: Presentation and Endovascular Management
Authors: Hassan Tamer , Nassar Mahmoud , Elghandour Mamdouh
Published: May 2011

Background: We present our experience with managing 13 cases of vein of Galen aneurysm with a special focus on endovascular strategies. This clinical review deals with the multivariable clinical presentation of vein of Galen aneurysms and the role of transarterial endovascular treatment. Methods: Thirteen patients diagnosed with vein of Galen aneurysms have been reviewed. Clinical presentation, diagnostic modalities and treatment strategies are also documented for each. MRI and three-dimensional CT angiogram (3D CTA) were performed for all patients. Transarterial embolization with Histoacryl was performed in 8 patients proved to have true vein of Galen aneurysmal malformation (VGAM). Results: Clinical presentation was variable including hydrocephalus, headaches, heart failure, coma, epilepsy, and even left orbital swelling. MRI demonstrated large vein of Galen aneurysms in all the cases. 3D CTA demonstrated true VGAM in 10 patients. Two cases proved to have vein of Galen varices. Endovascular treatment was conducted successfully in 8 patients and resulted in arrest of head growth, resolution of headaches and improvement of cardiac condition. Conclusion: The transarterial approach proved to be a successful way of management of true VGAM that yielded better outcomes.
Declining Stroke and Vascular Event Recurrence Rates in Secondary Prevention Trials Over the Past 50 Years and Consequences for Current Trial Design
Authors: Hong Keun-Sik , Yegiaian Sharon , Lee Meng , Lee Juneyoung , Saver Jeffrey L.
Published: May 2011

Background—

It is widely supposed, but not well-demonstrated, that cumulative advances in standard care have reduced recurrent stroke and cardiovascular events in secondary prevention trials.

Methods and Results—

Systematic search identified all randomized, controlled trials of medical secondary stroke prevention therapies published from 1960 to 2009. Randomized, controlled trials narrowly focused on single stroke mechanisms, including atrial fibrillation, cervical carotid stenosis, and intracranial stenosis, were excluded. From control arms of individual trials, we extracted data for baseline characteristics and annual event rates for recurrent stroke, fatal stroke, and major vascular events and analyzed trends over time. Fifty-nine randomized controlled trials were identified, enrolling 66 157 patients in control arms. Over the 5 decade periods, annual event rates declined, per decade, for recurrent stroke by 0.996% (
P
=0.001), fatal stroke by 0.282% (
P
=0.003), and major vascular events by 1.331% (
P
=0.001). Multiple regression analyses identified increasing antithrombotic use and lower blood pressures as major contributors to the decline in recurrent stroke. For recurrent stroke, annual rates fell from 8.71% in trials launched in the 1960s to 6.10% in the 1970s, 5.41% in the 1980s, 4.04% in the 1990s, and 4.98% in the 2000s. The sample size required for a trial to have adequate power to detect a 20% reduction in recurrent stroke increased 2.2-fold during this period.

Conclusions—

Recurrent stroke and vascular event rates have declined substantially over the last 5 decades, with improved blood pressure control and more frequent use of antiplatelet therapy as the leading causes. Considerably larger sample sizes are now needed to demonstrate incremental improvements in medical secondary prevention.
Prolonged Urocortin 2 Administration in Experimental Heart Failure
Authors: Rademaker Miriam T. , Charles Christopher J. , Ellmers Leigh J. , Lewis Lynley K. , Nicholls M. Gary , Richards A. Mark
Published: May 2011

Although acute administration of urocortin 2 has beneficial actions in heart failure, the integrated hemodynamic, hormonal, and renal effects of sustained urocortin 2 treatment in this disease have not been investigated. In the current study, we administered a 4-day infusion of a vehicle control (0.9% saline; n=6) or urocortin 2 (0.75 μg/kg per hour; n=6) to sheep with pacing-induced heart failure. Compared with time-matched controls, infusion of urocortin 2 produced rapid (30-minute) and persistent (4-day) improvements in cardiac contractility (day 4: control 905±73 versus urocortin 2 1424±158 mm Hg/s;
P
<0.001) and output (2.6±0.1 versus 3.8±0.3 L/min;
P
<0.001), together with reductions in left atrial pressure (28±1 versus 12±1 mm Hg;
P
<0.001) and peripheral resistance (30±2 versus 20±2 mm Hg/L per min;
P
<0.001). In contrast, urocortin 2–induced falls in mean arterial pressure were not established until the second day (day 4: 74±2 versus 72±2 mm Hg;
P
<0.05). Prolonged urocortin 2 administration was associated with sustained (days 0 to 4) declines in plasma renin activity (day 4: 1.33±0.27 versus 0.73±0.20 nmol/L per hour;
P
<0.001), aldosterone (970±383 versus 396±96 pmol/L;
P
<0.05), vasopressin (2.4±0.8 versus 1.3±0.1 pmol/L;
P
<0.05), endothelin 1 (7.2±0.7 versus 4.5±0.4 pmol/L;
P
<0.01), and atrial (269±27 versus 150±19 pmol/L;
P
<0.001) and B-type (65±9 versus 29±6 pmol/L;
P
<0.001) natriuretic peptides, as well as an acute transient rise in plasma cortisol (day 1:
P
<0.001). Chronic urocortin 2 also persistently augmented urinary sodium (day 4: 4-fold increase;
P
<0.001) and creatinine (1.4-fold;
P
<0.001) excretion and creatinine clearance (1.5-fold;
P
<0.01) compared with control. Food consumption was temporarily suppressed (
P
<0.05). In conclusion, 4-day urocortin 2 administration induces sustained improvements in hemodynamics and renal function, in association with inhibition of multiple vasoconstrictor/volume-retaining systems. These findings support the therapeutic potential for urocortin 2 in heart failure.
The Mnemosyne Atlas and the Meaning of Panel 79 in Aby Warburg's Oeuvre as a Distributed Object
Authors: Angel Sara
Published: May 2011

With his Mnemosyne Atlas Aby Warburg set out to find a revisionist method for studying art that surpassed its understanding through language. But his goal set up a new challenge. How does one comprehend what Warburg called an “art history without text” when he offered no explanation for its use? The following essay addresses this question utilizing a theoretical framework outlined by Alfred Gell in Art and Agency: Towards a New Anthropological Theory, which views an artist's output as a network of its creator's distributed personhood.
When the Rich Don't Get Richer: Equalizing Tendencies of Creative Networks
Authors: Bell John , Ippolito Jon
Published: May 2011

Analysis of the collaborative online environment The Pool suggests that inequalities in some creative networks may level out over time due to the long-term effects of user ratings.
The Social Network of Dante's Inferno
Authors: Cappelli Amedeo , Coscia Michele , Giannotti Fosca , Pedreschi Dino , Rinzivillo Salvo
Published: May 2011

This work aims to approach the phenomenon of culture through the development of new methods and more powerful tools to capture the content of digitally stored literary material. The authors chose as a test bed Dante's characters of al di là, a domain consisting in a set of data and relations complex enough to sharpen existing tools. The methods of investigation under development should help scholars of a literary text to concretize part of their interpretative intentions. For this purpose, the authors adopt advanced methodologies suitable to obtain a rich representation, expressing the multirelational network inherent in the text.
Cybernetic Bacteria 2.0
Authors: Dumitriu Anna , Whitby Blay
Published: May 2011

The transdisciplinary art project Cybernetic Bacteria 2.0 brings together an artist, a philosopher, a microbiologist, an artificial life programmer and an interactive media specialist, to investigate the relationship of the emerging science of bacterial communication to our own digital communications networks, looking in particular at ‘packet data’ and bacterial quorum sensing. The project seeks to reflect the complexity of communication taking place at a microscopic level in comparison with human communication technologies such as the Internet.
Evolution of Romance Language in Written Communication: Network Analysis of Late Latin and Early Romance Corpora
Authors: Mehler Alexander , Diewald Nils , Waltinger Ulli , Gleim Rüdiger , Esch Dietmar , Job Barbara , Küchelmann Thomas , Pustylnikov Olga , Blanchard Philippe
Published: May 2011

In this paper, the authors induce linguistic networks as a prerequisite for detecting language change by means of the Patrologia Latina, a corpus of Latin texts from the 4th to the 13th century.