bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunomodulatory and Protective Roles of Quorum-Sensing Signaling Molecules
N
-Acyl Homoserine Lactones during Infection of Mice with Aeromonas hydrophila
Authors: Khajanchi Bijay K. , Kirtley Michelle L. , Brackman Sheri M. , Chopra Ashok K.
Published: May 2011

Aeromonas hydrophila
leads to both intestinal and extraintestinal infections in animals and humans, and the underlying mechanisms leading to mortality are largely unknown. By using a septicemic mouse model of infection, we showed that animals challenged with
A. hydrophila
die because of kidney and liver damage, hypoglycemia, and thrombocytopenia. Pretreatment of animals with quorum-sensing-associated signaling molecules
N
-acyl homoserine lactones (AHLs), such as butanoyl and hexanoyl homoserine lactones (C
4
- and C
6
-HSLs), as well as
N
-3-oxododecanoyl (3-oxo-C
12
)-HSL, prevented clinical sequelae, resulting in increased survivability of mice. Since little is known as to how different AHLs modulate the immune response during infection, we treated mice with the above AHLs prior to lethal
A. hydrophila
infection. When we compared results in such animals to those in controls, the treated animals exhibited a significantly reduced bacterial load in the blood and other mouse organs, as well as various levels of cytokines/chemokines. Importantly, neutrophil numbers were significantly elevated in the blood of C
6
-HSL-treated mice compared to those in animals given phosphate-buffered saline and then infected with the bacteria. These findings coincided with the fact that neutropenic animals were more susceptible to
A. hydrophila
infection than normal mice. Our data suggested that neutrophils quickly cleared bacteria by either phagocytosis or possibly another mechanism(s) during infection. In a parallel study, we indeed showed that other predominant immune cells inflicted during
A. hydrophila
infections, such as murine macrophages, when they were pretreated with AHLs, rapidly phagocytosed bacteria, whereas untreated cells phagocytosed fewer bacteria. This study is the first to report that AHL pretreatment modulates the innate immune response in mice and enhances their survivability during
A. hydrophila
infection.
Iron-Regulated Lysis of Recombinant Escherichia coli in Host Releases Protective Antigen and Confers Biological Containment
Authors: Guan Lingyu , Mu Wei , Champeimont Jonathan , Wang Qiyao , Wu Haizhen , Xiao Jingfan , Lubitz Werner , Zhang Yuanxing , Liu Qin
Published: May 2011

The use of a recombinant bacterial vector vaccine is an attractive vaccination strategy to induce an immune response to a carried protective antigen. The superiorities of live bacterial vectors include mimicry of a natural infection, intrinsic adjuvant properties, and the potential for administration by mucosal routes.
Escherichia coli
is a simple and efficient vector system for production of exogenous proteins. In addition, many strains are nonpathogenic and avirulent, making it a good candidate for use in recombinant vaccine design. In this study, we screened 23 different iron-regulated promoters in an
E. coli
BL21(DE3) vector and found one, P
viuB
, with characteristics suitable for our use. We fused P
viuB
with lysis gene
E
, establishing an
in vivo
inducible lysis circuit. The resulting
in vivo
lysis circuit was introduced into a strain also carrying an IPTG (isopropyl-β-
d
-thiogalactopyranoside)-inducible P
T7
-controlled protein synthesis circuit, forming a novel
E. coli
-based protein delivery system. The recombinant
E. coli
produced a large amount of antigen
in vitro
and could deliver the antigen into zebrafish after vaccination via injection. The strain subsequently lysed in response to the iron-limiting signal
in vivo
, implementing antigen release and biological containment. The
gapA
gene, encoding the protective antigen GAPDH (glyceraldehyde-3-phosphate dehydrogenase) from the fish pathogen
Aeromonas hydrophila
LSA34, was introduced into the
E. coli
-based protein delivery system, and the resultant recombinant vector vaccine was evaluated in turbot (
Scophtalmus maximus
). Over 80% of the vaccinated fish survived challenge with
A. hydrophila
LSA34, suggesting that the
E. coli
-based antigen delivery system has great potential in bacterial vector vaccine applications.
The association between sedentary leisure and physical activity in middle-aged adults
Authors: Burton Nicola W , Khan Asaduzzaman , Brown Wendy J , Turrell Gavin
Published: May 2011

Aim

The aim of this study was to examine the association between time spent in sedentary leisure and physical activity level in mid-aged men and women.

Methods

Data were from the 2007 HABITAT study in Brisbane, Australia. A mail survey sent to 17 000 adults (40–65 years) provided 11 037 responses (68.5%), and 9121 (82.6%) were analysed. Sedentary leisure was quantified as hours/day spent sitting watching television, in home computer use, in general leisure, and overall, on a usual week and weekend day. Physical activity level (no activity, low, recommended, high, very high) included walking, moderate and vigorous activity combined into a measure of MET.min/week. Data were analysed separately for men and women using multilevel multinomial logistic regression with adjustment for sociodemographic and health variables.

Results

The only significant negative associations were between watching television on a week day and high activity in men (0.91; 0.83–0.98), and home computer use on a weekend day and very high activity in men (0.89; 0.81–0.98). For both men and women, there were significant positive associations between overall sedentary leisure time on a week day and very high activity (men: 1.07, 1.02–1.13; women: 1.10, 1.04–1.16), home computer use on a week day and very high activity (men: 1.11, 1.01–1.22; women: 1.15, 1.04–1.27) and general leisure on a week day and most activity levels.

Conclusions

Sedentary leisure is mainly independent of physical activity and does not preclude meeting physical activity recommendations.
Vascular anatomy of the spinal cord
Authors: Santillan Alejandro , Nacarino Veronica , Greenberg Edward , Riina Howard A , Gobin Y Pierre , Patsalides Athos
Published: May 2011

In this article, a detailed description of the normal arterial supply and venous drainage of the spinal cord is provided, and the role of catheter angiography and MR angiography in depicting the vascular anatomy of the spinal cord is discussed.
Geostatistical modeling of riparian forest microclimate and its implications for sampling
Authors: Eskelson Bianca N.I. , Anderson Paul. D. , Hagar Joan C. , Temesgen Hailemariam
Published: May 2011

Predictive models of microclimate under various site conditions in forested headwater stream – riparian areas are poorly developed, and sampling designs for characterizing underlying riparian microclimate gradients are sparse. We used riparian microclimate data collected at eight headwater streams in the Oregon Coast Range to compare ordinary kriging (OK), universal kriging (UK), and kriging with external drift (KED) for point prediction of mean maximum air temperature (Tair). Several topographic and forest structure characteristics were considered as site-specific parameters. Height above stream and distance to stream were the most important covariates in the KED models, which outperformed OK and UK in terms of root mean square error. Sample patterns were optimized based on the kriging variance and the weighted means of shortest distance criterion using the simulated annealing algorithm. The optimized sample patterns outperformed systematic sample patterns in terms of mean kriging variance mainly for small sample sizes. These findings suggest methods for increasing efficiency of microclimate monitoring in riparian areas.
Effects of aspect and type of competition on the early performance of Nothofagus dombeyi and Nothofagus nervosa in a mixed plantation
Authors: Donoso Pablo J. , Muñoz Ariel A. , Thiers Oscar , Soto Daniel P. , Donoso Claudio
Published: May 2011

In the Andes of Chile, two valuable Nothofagus tree species coexist (Nothofagus dombeyi (Mirb.) Oerst. and Nothofagus nervosa (Phil.) Krasser). They could provide an opportunity for mixed plantations because of their ecological differences. In a mixed plantation with a checkerboard design on a good site where the two species naturally coexist, we evaluated their performance according to aspect and type of competition. Nothofagus dombeyi had a greater survivorship (90% vs. 65%) and growth (twice in diameter and 20% greater in height). Forking was significantly lower in N. nervosa (23% vs. 70%). Aspect did not significantly affect the performance of N. dombeyi. The north aspect had a significant negative effect on survivorship of N. nervosa, but aspect did not significantly affect growth or forking of this species. The aspect – type of competition interaction was only significant for N. nervosa in diameter and marginally significant in height. The checkerboard design allowed for a clear separation of interspecific and intraspecific competition in this mixed plantation. Interspecific competition favored growth of N. nervosa on the north aspect (facilitation) and was detrimental to N. nervosa on the south aspect (competition). These results have a direct application when planting mixtures of species of complementary ecological characteristics that can increase the value of the plantation.
The potential cost of environmental certification to vegetation management in plantation forests: a New Zealand case study
Authors: Rolando Carol A. , Watt Michael S. , Zabkiewicz Jerzy A.
Published: May 2011

Plantation forests certified by the Forest Stewardship Council have restrictions on herbicide use. Since certified plantations are dependant on herbicides for cost-effective vegetation management, compliance requires a shift from current chemical practices. Using New Zealand plantation forests as a case study, discounted cash flow analyses were used to estimate the cost of certification-compliant vegetation control regimes compared with current non-compliant methods. We examined methods that (i) reduce the quantity of herbicides by using spot control and (ii) avoid the use of herbicides by using weed mats, manual, and mechanical control. Cost analyses were undertaken for low-, medium-, and high-productivity sites. The internal rate of return of the non-compliant regime was between 5% and 5.8% across the productivity range. Spot control was cheaper than current non-compliant practice. However, spot control is limited by site suitability and the availability of labour. Non-chemical control methods were expensive relative to other regimes. Reductions in the internal rate of return varied across low- and high-productivity sites between 0.8% and 0.5% for manual control, 1.3% and 0.8% for mechanical control, and 1.7% and 1.0% for weed mats. Meeting the goals of certification while retaining cost-effective vegetation control presents a challenge to the plantation forestry sector.
Simulating fuel treatment effects in dry forests of the western United States: testing the principles of a fire-safe forest
Authors: Johnson Morris C. , Kennedy Maureen C. , Peterson David L.
Published: May 2011

We used the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS) to simulate fuel treatment effects on 45 162 stands in low- to midelevation dry forests (e.g., ponderosa pine ( Pinus ponderosa Dougl. ex. P. & C. Laws.) and Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) of the western United States. We evaluated treatment effects on predicted post-treatment fire behavior (fire type) and fire hazard (torching index). FFE-FVS predicts that thinning and surface fuel treatments reduced crown fire behavior relative to no treatment; a large proportion of stands were predicted to transition from active crown fire pre-treatment to surface fire post-treatment. Intense thinning treatments (125 and 250 residual trees·ha–1) were predicted to be more effective than light thinning treatments (500 and 750 residual trees·ha–1). Prescribed fire was predicted to be the most effective surface fuel treatment, whereas FFE-FVS predicted no difference between no surface fuel treatment and extraction of fuels. This inability to discriminate the effects of certain fuel treatments illuminates the consequence of a documented limitation in how FFE-FVS incorporates fuel models and we suggest improvements. The concurrence of results from modeling and empirical studies provides quantitative support for “fire-safe” principles of forest fuel reduction (sensu Agee and Skinner 2005. For. Ecol. Manag. 211: 83–96).
Demography and spatial dynamics in balsam fir stands after a spruce budworm outbreak
Authors: Rossi Sergio , Morin Hubert
Published: May 2011

The renewal of balsam fir (Abies balsamea (L.) P. Mill.) stands is related to the recurrent spruce budworm (Archips fumiferana Clemens [syn.: Choristoneura fumiferana (Clemens)]) outbreaks that favour the growth of the regeneration following death of the dominant trees. The aim of this study was to investigate the population demography and the spatial relationships among individuals in four permanent plots of the boreal forest of Quebec, Canada, after a spruce budworm outbreak. This was realized by collecting data on trees and saplings every five years from 1994 to 2004 and by using Ripley’s K statistics. The younger plots showed recruitment of up to 90 new trees·ha–1·year–1, and mortality following competition among individuals affected up to 27% and 50% of the trees and saplings, respectively. In the plot with the lowest tree density, sapling recruitment was estimated as 378 new individuals·ha–1·year–1. Saplings were aggregated at all spatial scales, whereas trees showed a random pattern of stem distribution. A significant tendency to separation between saplings and trees was observed. The specific stand dynamics observed in balsam fir are connected to an abundant advance regeneration and an age-dependent competition for resources in a heterogeneous environment with different levels of resource availability.
Augmentation of cellular immune response byIpomoea obscuraand Ipobscurine alkaloid attenuates tumor growth in mice
Authors: Hamsa T.P. , Kuttan Girija
Published: May 2011

The immune status of the host plays a crucial role in controling the process of carcinogenesis. General or selective activation of various immunocompetent cells and their secretory function to maintain a healthy immune status may help in cancer prophylaxis, as well as therapy. The present study focused on the effect of Ipomoea obscura and Ipobscurine on cell-mediated immune response. In this study we evaluated the effect of I. obscura and an indole alkaloid fraction from I. obscura on effector mechanisms of cell-mediated immune response by analyzing cytotoxic T lymphocyte (CTL) activity, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC), and antibody-dependent complement-mediated cytotoxicity (ACC). The effect of I. obscura and Ipobscurine on interleukin-2 (IL-2) and interferon-γ (IFN-γ) levels was also analyzed. In the in vitro and in vivo systems, I. obscura and Ipobscurine treatment augmented cell-mediated immune response by enhancing the killing activity of CTL and NK cells from splenocytes in normal as well as tumor-bearing mice. ADCC and ACC were also enhanced significantly in both normal and tumor-bearing animals after drug administration, compared with untreated control. Administration of I. obscura and Ipobscurine significantly enhanced the production of IL-2 and IFN-γ in normal as well as tumor-bearing animals. This study reveals that both I. obscura and Ipobscurine have the potential to augment immune response through the enhanced secretion of IL-2 and IFN-γ by T cells and thereby inhibit tumor growth and as an alternative medicine for cancer treatment.
Profound cardioprotection with timolol in a female rat model of aging-related altered left ventricular function
Authors: Sozmen Nazli N. , Tuncay Erkan , Bilginoglu Ayca , Turan Belma
Published: May 2011

Increasing evidence shows a marked beneficial effect with β-blockers in heart dysfunction via scavenging reactive oxygen species. Previously we showed that chronic treatment with either timolol or propranolol possessed similar beneficial effects for heart function in male rats as age increased, whereas only timolol exerted similar benefits in female rats. Therefore, in this study, we aimed first to examine the cellular bases for age-related alterations in excitation–contraction coupling in ventricular myocytes from female rats and, second, to investigate the hypothesis that age-related changes in [Ca2+]ihomeostasis and receptor-mediated system can be prevented with chronic timolol treatment. Chronic timolol treatment of 3-month-old female rats abolished age-related decrease in left ventricular developed pressure and the attenuated responses to β-adrenoreceptor stimulation. It also normalized the altered parameters of [Ca2+]itransients, decreased Ca2+loading of sarcoplasmic reticulum and increased basal [Ca2+]i, and decreased L-type Ca2+currents in 12-month-old female rats compared with the 3-month-old group. Adenylyl cyclase activity, β-adrenoreceptor affinity to its agonist, and β-adrenoreceptor density of the 12-month-old group are normalized to those of the 3-month-old group. Moreover, timolol treatment prevented dysfunction of the antioxidant system, including increased lipid peroxidation, decreased ratio of reduced glutathione to oxidized glutathione, and decreased activities of thioredoxin reductase and glucose-6-phosphate dehydrogenase, in the left ventricle of hearts from the 12-month-old group. Our data confirmed that aging-related early myocardial impairment is primarily related to a dysfunctional antioxidant system and impairment of Ca2+homeostasis, which can be prevented with chronic timolol treatment.
HIGHLY NONLINEAR COMPLEXITY OF INTERACTION DYNAMICS IN SCALE-FREE NETWORKS
Authors: TANG SHAOTING , JIANG XIN , PEI SEN , LIU ZHICONG , MA LILI , ZHANG ZHANLI , ZHENG ZHIMING
Published: May 2011

Interaction dynamics induced by finite-capacity effect is a typical diffusion model on networks. Although several significant properties of it like condensation have been well studied, the origin of its highly nonlinear complexity, influenced by complex structure and interactive behavior, is still missing. Aimed at filling this gap, we propose entropy to quantify the complexity and exhibit its strong dependence on two coupled crucial elements of nodes, the local topology and the finite capacity. Further, the performance of interaction dynamics, efficiency function is also analyzed in terms of entropy rate and relatively promoted through routing strategy arguments supported by maximum entropy theory studies. This will play a crucial role for inference problems emerging in the field of interaction dynamics on complex networks.
CRITICAL BEHAVIOR OF THE CONTACT PROCESS DELAYED BY INFECTION AND IMMUNIZATION PERIODS
Authors: DA SILVA P. C. , LYRA M. L. , DA SILVA L. R. , CORSO G. , FULCO U. L.
Published: May 2011

We analyze the absorbing state phase transition exhibited by two distinct unidimensional delayed contact process (CP). The first is characterized by the introduction of an infection period and the second by an immune period in the dynamics of the original model. We characterize these CP by the quantities t d (infection or disease period) and t i (immune period). The quantity t d corresponds to the period interval an individual remains infected after being contaminated, while the period t i is the time interval an individual remains immune after being cured. We used Monte Carlo simulations to compute the critical parameters associated with the absorbing state phase transition exhibited by these models. We find two distinct power-law scale relations for the critical infection rate [Formula: see text] and the critical cure rate [Formula: see text]. For the CP delayed by the minimum infection period we find μd = 0.98, while we obtained μi = 0.80 for the case of a delay due to immunity. In addition, we used a finite-size scaling analysis to estimate the critical exponents β/ν and ν, and found that these models belong to the universality class of directed percolation irrespective to the time delay.
MICROSCOPIC MECHANISM OF THE GIANT ELECTRORHEOLOGICAL EFFECT
Authors: CHEN SHUYU , HUANG XIANXIANG , WEN WEIJIA , SHENG PING , VAN DER VEGT NICO F. A.
Published: May 2011

Electrorheological (ER) fluids are a type of colloids whose rheological characteristics can be varied reversibly with the application of an electric field. The traditional ER mechanism is based on induced polarization arising from the dielectric constant contrast between the suspended solid particles and the fluid. However, for induced polarization there is a maximum value for the dimensionless electric susceptibility χ ∼ 0.24. That implies an upper bound for the traditional ER effect. For permanent molecular dipoles, χ can be as high as 4–50. Thus, one to two orders of magnitude higher electric energy can be gained by harnessing the molecular dipoles. Indeed, the recent discovery of the giant electrorheological (GER) effect, in nanoparticles of urea-coated barium titanate oxalate suspended in silicone oil, has shown that the theoretical upper bound of the traditional ER effect is no longer applicable to this new type of electrorheological fluid. A phenomenological model of the GER mechanism, based on aligned molecular dipoles of urea molecules in the contact regions of the nanoparticles, yields an adequate account of the observed effect but without a microscopic picture on how this can occur. More recently, by using molecular dynamics (MD) to simulate the urea-silicone oil mixture confined between two bounding surfaces of a nanocontact, we find that the urea molecules, which has a molecular dipole moment of 4.6 Debye, can form aligned dipolar filaments that penetrate the oil film to bridge the two substrates, with the attendant lowering of the aligning field for the urea dipoles. This phenomenon is explainable on the basis of a 3D to 1D crossover in urea molecules' microgeometry, realized through the confinement effect provided by the oil chains. The resulting electrical energy density is shown to give an excellent account of the observed yield stress variation as a function of the electric field.
UNDERSTANDING ELECTRIC INTERACTIONS IN SUSPENSIONS IN GRADIENT AC ELECTRIC FIELDS II: SIMULATIONS AND APPLICATION EXPLORATION
Authors: TADA SHIGERU , SHEN YAN , JACQMIN DAVID , FU BINGMEI , QIU ZHIYONG
Published: May 2011

We used numerical simulations of a continuous model and the molecular dynamics model to understand the particle instability, formation of island-like structures and existence of one critical particle concentration of 1% (v/v) for formation of island-like structures in the suspension in a gradient AC electric field reported in Paper I. The simulations of the continuous model show that the critical concentration of 1% (v/v) is the concentration of which the particles of a suspension are just fully filling the lower field region finally. According to the MD simulations, the particles instability does exist in the corn oil in a gradient AC electric field, anisotropic polarization interactions among the particles are responsible for the particle instability and have memory, and the memory is still kept even when the particles are transported by a dielectrophoresis force. The island-like structures can be regarded as signature of the memory. We explored possibilities to apply our findings in biomedical fields.
LINEWIDTH OF PHONONS IN ORDER–DISORDER PHASE TRANSITIONS WITH RANDOM TELEGRAPH NOISE
Authors: KARACALI H. , YURTSEVEN H.
Published: May 2011

We derive an expression for the linewidth of phonons involved in the order–disorder phase transitions in solids. The linewidth is obtained as a function of the dwell time from which the activation energy can be computed. A new viewpoint is presented on the assumption that the fluctuations in the random variable of the noise, which is carried by the random particles involved in the order–disorder mechanism, affect the linewidth of the phonons.
H(z) DIAGNOSTICS ON THE NATURE OF DARK ENERGY
Authors: DEL CAMPO SERGIO , HERRERA RAMÓN , PAVÓN DIEGO
Published: May 2011

The two dominant components of the cosmic budget today, pressureles matter and dark energy, may or may not be interacting with each other. Currently, both possibilities appear compatible with observational data. We propose several criteria based on the history of the Hubble factor that can help discern whether they are interacting and whether dark energy is phantom or quintessence in nature.
THE CRAB: A CONNECTED FRACTILE OF INFINITE CONNECTIVITY
Authors: HELMBERG GILBERT
Published: May 2011

In the plane IR2, let A0 be the unit interval on the x-axis, and let A(1) be the polygonal path with nodes (0, 0), [Formula: see text], (½, 0), [Formula: see text], (1, 0). Let S be the operator which, applied to a segment B(0) in IR2, replaces it by a polygonal path B(1) = SB(0), a similar copy of A(1), but with the same endpoints as B(0). Denote by S(n) the n-th iterate of S. The limit set (with respect to the Hausdorff metric) A(∞) = lim n → ∞ S(n)A(0) is a space-filling curve which is the closure of its interior and the union of four half-size copies of itself, intersecting only in their boundaries. Although A(∞) is of infinite connectivity, it is a tile tessellating the plane. It is related to the set of Eisenstein fractions and has a boundary of Hausdorff dimension [Formula: see text]
THE RECONSTRUCTION OF SATELLITE IMAGES BASED ON FRACTAL INTERPOLATION
Authors: CHEN CHING-JU , CHENG SHU-CHEN , HUANG Y. M.
Published: May 2011

This study discussed the application of a fractal interpolation method in satellite image data reconstruction. It used low-resolution images as the source data for fractal interpolation reconstruction. Using this approach, a high-resolution image can be reconstructed when there is only a low-resolution source image available.

The results showed that the high-resolution image data from fractal interpolation can effectively enhance the sharpness of the border contours. Implementing fractal interpolation on an insufficient image resolution image can avoid jagged edges and mosaic when enlarging the image, as well as improve the visibility of object features in the region of interest. The proposed approach can thus be a useful tool in land classification by satellite images.
MULTIFRACTAL DETRENDED CROSS-CORRELATION ANALYSIS OF CHINESE STOCK MARKETS BASED ON TIME DELAY
Authors: ZHAO XIAOJUN , SHANG PENGJIAN , JIN QIUYUE
Published: May 2011

Multifractal detrended cross-correlation analysis (MF-DXA) has been developed to detect the long-range power-law cross-correlation of two simultaneous series. However, the synchronization of underlying data can not be guaranteed integrated by a variety of factors. We artificially imbed a time delay in considered series and study its influence on the multifractal cross-correlation analysis. Time delay is found to affect the multifractal characterization, where a larger time delay causes a weaker multifractality. We also propose an alternative modification on MF-DXA to make the process more robust. The logarithmic return and volatility of Chinese stock indices show cross-correlation scaling behavior and strong multifractality by MF-DXA as well as singularity spectrum analysis.
A NEW FRACTAL INTERPOLATION ALGORITHM AND ITS APPLICATIONS TO SELF-AFFINE SIGNAL RECONSTRUCTION
Authors: ZHAI MING-YUE , FERNÁNDEZ-MARTÍNEZ JUAN LUIS , RECTOR JAMES W.
Published: May 2011

A new fractal interpolation method called PPA (Pointed Point Algorithm) based on IFS is proposed to interpolate the self-affine signals with the expected interpolation error, solving the problem that the ordinary fractal interpolation can't get the value of any arbitrary point directly, which has not been found in the existing literatures. At the same time, a new method to calculate the vertical scaling factors is proposed based on the genetic algorithm, which works together with the PPA algorithm to get the better interpolation performance. Experiments on the theoretical data and real field seismic data show that the proposed interpolation schemes can not only get the expected point's value, but also get a great accuracy in reconstruction of the seismic profile, leading to a significant improvement over other trace interpolation methods.
FLUCTUATIONS OF THE RIEMANN STAIRCASE
Authors: LAN BOON LEONG
Published: May 2011

The one-sided power spectrum of the fluctuations of the Riemann staircase is calculated numerically and shown to be Lorentzian, like the one-sided power spectrum of the fluctuations of the spectral staircase for classically chaotic systems. This result provides further evidence in support of Berry's conjecture that the En's of the enigmatic Riemann zeroes 1/2 + iEn are real because they are the quantized energies of a system which is classically chaotic.
LIMIT LAWS FOR ERGODIC PROCESSES
Authors: THOUVENOT JEAN-PAUL , WEISS BENJAMIN
Published: May 2011

The study of limit laws for normalized sums of a sequence of random variables is one of the classical topics in probability theory. We give here two results showing that ergodic stationary processes can admit an arbitrary distribution as the limit of normalized sums. In the first, we take the usual average of the first n variables, but the process is not integrable. In the second, the variables take on only two values and the sequence of normalizing constants is constructed inductively. In both cases the processes can be defined as factors of an arbitrary aperiodic measure preserving system.
PERIODIC FIRST INTEGRALS FOR HAMILTONIAN SYSTEMS OF LIE TYPE
Authors: FLORES ESPINOZA RUBEN
Published: May 2011

In this paper, we study the existence problem of periodic first integrals for periodic Hamiltonian systems of Lie type. From a natural ansatz for time-dependent first integrals, we refer their existence to the existence of periodic solutions for a periodic Euler equation on the Lie algebra associated to the original system. Under different criteria based on properties for the Killing form or on exponential properties for the adjoint group, we prove the existence of Poisson algebras of periodic first integrals for the class of Hamiltonian systems considered. We include an application for a nonlinear oscillator having relevance in some modern physics applications.
STOCHASTIC EINSTEIN EQUATIONS
Authors: DZHUNUSHALIEV VLADIMIR
Published: May 2011

Stochastic Einstein equations are considered when three-dimensional space metric γij are stochastic functions. The probability density for the stochastic quantities is connected with Perelman's entropy functional. As an example, the Friedman Universe is considered. It is shown that for the Friedman Universe the dynamical evolution is not changed. The connection between general relativity and Ricci flow is discussed.
ISOMETRIC IMMERSIONS INTO LORENTZIAN PRODUCTS
Authors: ROTH JULIEN
Published: May 2011

We give a necessary and sufficient condition for an n-dimensional Riemannian manifold to be isometrically immersed into one of the Lorentzian products 𝕊n× ℝ1or ℍn× ℝ1. This condition is expressed in terms of its first and second fundamental forms, the tangent and normal projections of the vertical vector field. As applications, we give an equivalent condition in a spinorial way and we deduce the existence of a one-parameter family of isometric maximal deformation of a given maximal surface obtained by rotating the shape operator.
Consumer trust in e-commerce web sites
Authors: Beatty Patricia , Reay Ian , Dick Scott , Miller James
Published: May 2011

Trust is at once an elusive, imprecise concept, and a critical attribute that must be engineered into e-commerce systems. Trust conveys a vast number of meanings, and is deeply dependent upon context. The literature on engineering trust into e-commerce systems reflects these ambiguous meanings; there are a large number of articles, but there is as yet no clear theoretical framework for the investigation of trust in e-commerce.
E
-commerce, however, is predicated on trust; indeed, any e-commerce vendor that fails to establish a trusting relationship with their customers is doomed. There is a very clear need for specific guidance on e-commerce system attributes and business operations that will effectively promote consumer trust. To address this need, we have conducted a meta-study of the empirical literature on trust in e-commerce systems. This area of research is still immature, and hence our meta-analysis is qualitative rather than quantitative. We identify the major theoretical frameworks that have been proposed in the literature, and propose a qualitative model incorporating the various factors that have been empirically found to influence consumer trust in e-commerce. As this model is too complex to be of practical use, we explore subsets of this model that have the strongest support in the literature, and discuss the implications of this model for Web site design. Finally, we outline key conceptual and methodological needs for future work on this topic.
Human activity analysis
Authors: Aggarwal J.K. , Ryoo M.S.
Published: May 2011

Human activity recognition is an important area of computer vision research. Its applications include surveillance systems, patient monitoring systems, and a variety of systems that involve interactions between persons and electronic devices such as human-computer interfaces. Most of these applications require an automated recognition of high-level activities, composed of multiple simple (or atomic) actions of persons. This article provides a detailed overview of various state-of-the-art research papers on human activity recognition. We discuss both the methodologies developed for simple human actions and those for high-level activities. An approach-based taxonomy is chosen that compares the advantages and limitations of each approach.

Recognition methodologies for an analysis of the simple actions of a single person are first presented in the article. Space-time volume approaches and sequential approaches that represent and recognize activities directly from input images are discussed. Next, hierarchical recognition methodologies for high-level activities are presented and compared. Statistical approaches, syntactic approaches, and description-based approaches for hierarchical recognition are discussed in the article. In addition, we further discuss the papers on the recognition of human-object interactions and group activities. Public datasets designed for the evaluation of the recognition methodologies are illustrated in our article as well, comparing the methodologies' performances. This review will provide the impetus for future research in more productive areas.
Strict intersection types for the Lambda Calculus
Authors: Bakel Steffen Van
Published: May 2011

This article will show the usefulness and elegance of strict intersection types for the Lambda Calculus, that are strict in the sense that they are the representatives of equivalence classes of types in the BCD-system [Barendregt et al. 1983]. We will focus on the essential intersection type assignment; this system is almost syntax directed, and we will show that all major properties hold that are known to hold for other intersection systems, like the approximation theorem, the characterization of (head/strong) normalization, completeness of type assignment using filter semantics, strong normalization for cut-elimination and the principal pair property. In part, the proofs for these properties are new; we will briefly compare the essential system with other existing systems.
Edge-aware color appearance
Authors: Kim Min H. , Ritschel Tobias , Kautz Jan
Published: May 2011

Color perception is recognized to vary with surrounding spatial structure, but the impact of edge smoothness on color has not been studied in color appearance modeling. In this work, we study the appearance of color under different degrees of edge smoothness. A psychophysical experiment was conducted to quantify the change in perceived lightness, colorfulness, and hue with respect to edge smoothness. We confirm that color appearance, in particular lightness, changes noticeably with increased smoothness. Based on our experimental data, we have developed a computational model that predicts this appearance change. The model can be integrated into existing color appearance models. We demonstrate the applicability of our model on a number of examples.
Nonutilization bounds and feasible regions for arbitrary fixed-priority policies
Authors: Liu Xue , Abdelzaher Tarek
Published: May 2011

Prior research on schedulability bounds focused primarily on bounding
utilization/
as a means to meet deadline constraints. Nontrivial bounds were found for a handful of scheduling policies in which utilization is directly related to the ability of the policy to meet deadlines. Examples include rate-monotonic, deadline-monotonic, and EDF scheduling. For most other scheduling policies, however, utilization is not correlated with schedulability. For example, shortest-job-first can miss deadlines at an arbitrarily low utilization. This raises the question of whether or not some other nonutilization-based metric might be more indicative of schedulability in those cases. This article answers the above question positively by extending the notion of schedulability bounds, in a uniform manner, to arbitrary (fixed) priorities and nonutilization metrics. We present a simple function that generates the schedulability metric to be bounded from the definition of a fixed-priority scheduling policy, and derive a nontrivial schedulability bound on that metric for aperiodic tasks. It is shown that the generated metrics and bounds are valid in that no deadline misses occur when these bounds are not violated. This result allows efficient real-time admission control to be performed in systems with arbitrary fixed-priority scheduling policies. As an example, we illustrate applying schedulability bounds for admission control to shortest-job-first and velocity-monotonic scheduling. While the proposed nonutilization bounds and feasible regions are derived for fixed-priority scheduling policies, the authors are investigating extensions of the results to dynamic-priority scheduling.
Fast multidimension multichoice knapsack heuristic for MP-SoC runtime management
Authors: Ykman-Couvreur Ch. , Nollet V. , Catthoor F. , Corporaal H.
Published: May 2011

Since the application complexity is growing and applications can be dynamically activated, the major challenge for heterogeneous multiprocessor platforms is to select at runtime an energy-efficient mapping of these applications. Taking into account that many different possible implementations per application can be available, and that the selection must meet the application deadlines under the available platform resources, this runtime optimization problem can be modeled as a Multidimension Multichoice Knapsack Problem (MMKP), which is known to be NP-hard. Not only algorithms for an optimal solution, but also state-of-the-art heuristics for real-time systems are still too slow for runtime management of multiprocessor platforms. This article provides a new fast and lightweight heuristic for finding near-optimal solutions for MMKP problems. The main contribution of this heuristic is: (i) the Pareto filtering of each initial MMKP set to reduce the search space, (ii) the sorting of all Pareto points together in a single two-dimension search space, where (iii) a very fast greedy algorithm solves the MMKP. Experiments show that our heuristic finds solutions close (within 0% to 0.4%) to the ones obtained by the fastest state-of-the-art heuristics, in just a fraction of the execution time (more than 97.5% gain on a StrongARM processor) and can run in less than 1ms for multiprocessor problem sizes. This is required for realistic OS reaction times in video and wireless application sets.
Deterministic finite automata characterization and optimization for scalable pattern matching
Authors: Vespa Lucas , Weng Ning
Published: May 2011

Memory-based Deterministic Finite Automata (DFA) are ideal for pattern matching in network intrusion detection systems due to their deterministic performance and ease of update of new patterns, however severe DFA memory requirements make it impractical to implement thousands of patterns. This article aims to understand the basic relationship between DFA characteristics and memory requirements, and to design a practical memory-based pattern matching engine. We present a methodology that consists of theoretical DFA characterization, encoding optimization, and implementation architecture. Results show the validity of the characterization metrics, effectiveness of the encoding techniques, and efficiency of the memory-based pattern engines.
Parallelization libraries
Authors: Bhattacharjee Abhishek , Contreras Gilberto , Martonosi Margaret
Published: May 2011

Creating efficient, scalable dynamic parallel runtime systems for chip multiprocessors (CMPs) requires understanding the overheads that manifest at high core counts and small task sizes.

In this article, we assess these overheads on Intel's Threading Building Blocks (TBB) and OpenMP. First, we use real hardware and simulations to detail various scheduler and synchronization overheads. We find that these can amount to 47% of TBB benchmark runtime and 80% of OpenMP benchmark runtime. Second, we propose load balancing techniques such as occupancy-based and criticality-guided task stealing, to boost performance.

Overall, our study provides valuable insights for creating robust, scalable runtime libraries.
Blended interaction spaces for distributed team collaboration
Authors: O'hara Kenton , Kjeldskov Jesper , Paay Jeni
Published: May 2011

In recent years there has been an introduction of sophisticated new video conferencing technologies (e.g., HP Halo, Cisco Telepresence) that have led to enhancements in the collaborative user experience over traditional video conferencing technologies. Traditional video conferencing set-ups often distort the shared spatial properties of action and communication due to screen and camera orientation disparities and other asymmetries. These distortions affect access to the common resources used to mutually organize action and communication. By contrast, new systems, such as Halo, are physically configured to reduce these asymmetries and orientation disparities, thereby minimizing these spatial distortions. By creating appropriate shared spatial geometries, the distributed spaces become “blended” where the spatial geometries of the local space continue coherently across the distributed boundary into the remote site, providing the illusion of a single unified space. Drawing on theories of embodied action and workplace design we discuss the importance of this geometric “blending” of space for distributed collaboration and how this is achieved in systems such as Halo. We then extend these arguments to explore the concept of
Blended Interaction Spaces
: blended spaces in which interactive groupware is incorporated in ways spatially consistent with the physical geometries of the video-mediated set-up. We illustrate this discussion through a system called BISi that introduces interactive horizontal and vertical multipoint surfaces into a blended video-mediated collaboration space. In presenting this system, we highlight some of the particular challenges of creating these systems arising from the spatial consequences of different interaction mechanisms (e.g., direct touch or remote control) and how they affect movement and spatial configuration of people in these spaces.
Contextual Video Recommendation by Multimodal Relevance and User Feedback
Authors: Mei Tao , Yang Bo , Hua Xian-Sheng , Li Shipeng
Published: May 2011

With Internet delivery of video content surging to an unprecedented level, video recommendation, which suggests relevant videos to targeted users according to their historical and current viewings or preferences, has become one of most pervasive online video services. This article presents a novel contextual video recommendation system, called VideoReach, based on multimodal content relevance and user feedback. We consider an online video usually consists of different modalities (i.e., visual and audio track, as well as associated texts such as query, keywords, and surrounding text). Therefore, the recommended videos should be relevant to current viewing in terms of multimodal relevance. We also consider that different parts of videos are with different degrees of interest to a user, as well as different features and modalities have different contributions to the overall relevance. As a result, the recommended videos should also be relevant to current users in terms of user feedback (i.e., user click-through). We then design a unified framework for VideoReach which can seamlessly integrate both multimodal relevance and user feedback by relevance feedback and attention fusion. VideoReach represents one of the first attempts toward contextual recommendation driven by video content and user click-through, without assuming a sufficient collection of user profiles available. We conducted experiments over a large-scale real-world video data and reported the effectiveness of VideoReach.
Effects of Usage-Based Feedback on Video Retrieval
Authors: Vallet David , Hopfgartner Frank , Jose Joemon M. , Castells Pablo
Published: May 2011

We present a model for exploiting community-based usage information for video retrieval, where implicit usage information from past users is exploited in order to provide enhanced assistance in video retrieval tasks, and alleviate the effects of the semantic gap problem. We propose a graph-based model for all types of implicit and explicit feedback, in which the relevant usage information is represented. Our model is designed to capture the complex interactions of a user with an interactive video retrieval system, including the representation of sequences of user-system interaction during a search session. Building upon this model, four recommendation strategies are defined and evaluated. An evaluation strategy is proposed based on simulated user actions, which enables the evaluation of our recommendation strategies over a usage information pool obtained from 24 users performing four different TRECVid tasks. Furthermore, the proposed simulation approach is used to simulate usage information pools with different characteristics, with which the recommendation approaches are further evaluated on a larger set of tasks, and their performance is studied with respect to the scalability and quality of the available implicit information.
An internet of things that do not exist
Authors: Speed Chris
Published: May 2011

On Heritage aims to offer and promote a rich discussion at the intersection of art, performance, and culture that expands the boundaries of HCI while broadening our understanding of how things of the past come to matter in the present.