bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerodynamic Analysis of Projectile in Gun System Firing Process
Authors: Yu Wei , Zhang Xiaobing
Published: April 2010

During a gun firing, the flow around a projectile will be developing and changing. In particular, the flow around the projectile is disturbed significantly when the projectile overtakes the muzzle flow. Furthermore, the projectile body pressure will also change substantially. Therefore, the shot ejection process has an important effect on the shot accuracy. The maximum projectile velocity is one of the most important design goals of the interior ballistic process and also is the initial condition for the exterior ballistic process. Most researchers take the muzzle velocity as the maximum projectile velocity; actually, after the projectile exits the muzzle, the projectile velocity will increase further due to the influence of the muzzle flow. Most investigations of the muzzle flow focused on the blowout of the high-pressure jet flow after the projectile exited the muzzle. The interior ballistic process was ignored or simply assumed in most investigations. Also, the mutual influence between the moving projectile and the muzzle flow was often neglected. Actually, a precursor shock flow near the muzzle is formed before the projectile exits. This precursor muzzle flow has an important influence on the trajectory of the projectile, especially, for the prevalent trend of gun systems including large caliber cannon and multiple launch gun systems. For these reasons, the interior ballistic process was coupled with the simulation of the flow near the muzzle. A hybrid structured-unstructured gridding method was used to simulate the process from the projectile engraving to the gas ejection phase, accounting for the moving projectile. The simulation results show that the projectile muzzle velocity was 893.99 m/s but the maximum velocity was 899.28 m/s. The projectile velocity increased rapidly to up to 0.8 ms after muzzle exit; thereafter, the projectile velocity increased slowly before reaching its maximum value. The maximum Mach number of the effluent gas increased to 6.83 and the breech pressure decreased to 21.5 MPa at 1.8 ms after the projectile exited the muzzle. The formation and development of the muzzle flow field was highly complex and transient. The analysis of the projectile velocity was conducted during the interior ballistic after-effect period. The predicted muzzle velocity and maximum barrel pressure are in good agreement with those measured in gun firings. Results of the numerical simulation and analysis are helpful to understand and master the aerodynamic process of gun system launching and provide significant guidance for research into shot accuracy and muzzle brake design.
Coadministration of a Tumor-Penetrating Peptide Enhances the Efficacy of Cancer Drugs
Authors: Sugahara Kazuki N. , Teesalu Tambet , Karmali Priya Prakash , Kotamraju Venkata Ramana , Agemy Lilach , Greenwald Daniel R. , Ruoslahti Erkki
Published: April 2010

Penetrating Attack on Tumors

While considerable research effort in oncology is focused on the design of new cancer drugs, an important but relatively understudied research area is the development of methods that optimize the delivery and tumor penetration of existing cancer drugs. Previous work has characterized a peptide (iRGD) that selectively targets and penetrates tumor tissue by virtue of its specific interaction with tumor blood vessels. Now, studying mouse models,

Sugahara
et al.

(p.
1031
, see the cover) show that coinjection of the iRGD peptide increases the tumor penetration and antitumor activity of several cancer drugs, including the cytotoxic agent doxorubicin and the therapeutic antibody trastuzumab (Herceptin), without increasing their harmful effects on healthy tissue. Importantly, these effects did not require chemical conjugation of the cancer drugs to the peptide.
Recent Hotspot Volcanism on Venus from VIRTIS Emissivity Data
Authors: Smrekar Suzanne E. , Stofan Ellen R. , Mueller Nils , Treiman Allan , Elkins-Tanton Linda , Helbert Joern , Piccioni Giuseppe , Drossart Pierre
Published: April 2010

Hotspots on Venus

The surface of Venus shows clear signs of volcanism, but are there active volcanoes on Venus today? The answer to this question will bear on our understanding of the planet's climate evolution and interior dynamics. Using surface thermal emissivity data returned by the Venus Express spacecraft,

Smrekar
et al.

(p.
605
, published online 8 April) looked at three hotspots on Venus. These places were identified by analogy with terrestrial hotspots like Hawaii, which are believed to overlie mantle plumes and to be the most likely sites for current volcanic activity. Lava flows at the three hotspots have anomalously high thermal emissions when compared with their surroundings. Low emissivity is generally interpreted as the result of surface alteration by the corrosive atmosphere of Venus. High emissivity implies that not much alteration took place and thus that the hotspots must represent recently active volcanoes younger than 2.5 million years.
Assessing the relationship between ad volume and awareness of a tobacco education media campaign
Authors: Cowling David W , Modayil Mary V , Stevens Colleen
Published: April 2010

Background

The relation between aided ad recall and level of television ad placement in a public health setting is not well established. We examine this association by looking back at 8 years of the California's Tobacco Control Program's (CTCP) media campaign.

Methods

Starting in July 2001, California's campaign was continuously monitored using five telephone series of surveys and six web-based series of surveys immediately following a media flight. We used population-based statewide surveys to measure aided recall for advertisements that were placed in each of these media flights. Targeted rating points (TRPs) were used to measure ad placement intensity throughout the state.

Results

Cumulative TRPs exhibited a stronger relation with aided ad recall than flight TRPs or TRP density. This association increased after log-transforming cumulative TRP values. We found that a one-unit increase in log-cumulative TRPs led to a 13.6% increase in aided ad recall using web-based survey data, compared to a 5.3% increase in aided ad recall using telephone survey data.

Conclusions

In California, the relation between aided ad recall and cumulative TRPs showed a diminishing return after a large volume of ad placements These findings may be useful in planning future ad placement for CTCP's media campaign.
Evaluation of California's in-school tobacco use prevention education (TUPE) activities using a nested school-longitudinal design, 2003–2004 and 2005–2006
Authors: Park Hye-Youn , Dent Clyde , Abramsohn Erin , Dietsch Barbara , McCarthy William J
Published: April 2010

Background

Current legislative language requires the California Department of Public Health, California Tobacco Control Program, to evaluate the effectiveness of the school-based Tobacco Use Prevention Education (TUPE) programme in California every 2 years. The objective of the study was to measure change and to identify the impact of school-based tobacco use prevention education activities on youth smoking prevalence and attitudes over time, spanning two school year surveys (2003–2004 and 2005–2006).

Methods

Evaluation focused on school-based tobacco use prevention activities in 57 schools (student sample size, n=16 833) that participated in the in-school administration of the 2003–2004 and 2005–2006 California Student Tobacco Surveys. Hierarchical linear models were used to predict student tobacco use and precursors to tobacco use.

Results

Overall, student tobacco use, intention to smoke, number of friends smoking and perceived smoking prevalence by peers increased as students moved through grades 9 and 10 to grades 11 and 12. TUPE-related activities showed a suggestive association (p=0.06) with reduced rate in student tobacco use between the two surveys after adjusting for other contextual factors such as each school's socioeconomic characteristics.

Conclusions

TUPE activities appears to be beneficial in reducing tobacco use in California high school students over time. Other contextual factors were important moderating influences on student tobacco use.
Policy-driven tobacco control
Authors: Francis John A , Abramsohn Erin M , Park Hye-Youn
Published: April 2010

Background

Since the passage of Proposition 99, California's comprehensive tobacco control programme has benefited from a localised policy adoption process that allows for the innovation and diffusion of strong local tobacco control policies throughout the state.

Methods

The policy adoption continuum is described in the context of California's smoke-free workplace movement, and the influence of policy-driven tobacco control initiatives on social norms, behaviour and the public's health was examined.

Results

The Smoke-free California policy adoption continuum reflects a general approach for policy innovation and diffusion that builds social acceptance and influences social norms, while minimising unintended consequences and creating best practices in tobacco control. California's local smoke-free workplace policies have reduced secondhand smoke exposure and supported attitude and behaviour changes. The effects of local policy adoption led to the nation's first statewide smoke-free workplace law.

Conclusions

Proposition 99 created an unprecedented tobacco control infrastructure that supported local policy innovation and diffusion to influence social norms and behaviours. Tobacco control policy efforts should address campaign challenges, oppose pre-emption and confront tobacco industry influence. Advocates must be cautious of pursuing a statewide policy prematurely, as it may result in a weak and/or pre-emptive policy that can stymie local policy efforts and prolong the adoption of a meaningful statewide policy.
Leucine supplementation favors liver protein status but does not reduce body fat in rats during 1 week of food restriction
Authors: Pedrosa Rogerio G. , Donato Jose , Pires Ivanir S. , Tirapegui Julio
Published: April 2010

An important role in protein–energy metabolism has been attributed to leucine because of its long-term effects on body fat reduction and on the improvement of some indicators of protein status in rodents. The present study investigated the influence of leucine supplementation on the body composition and protein status of rats during the early phase of weight loss, which is characterized by a rapid loss of body weight. Thirty adult male Wistar rats were divided into 2 groups, a control and a leucine group (diet supplemented with 0.59% L-leucine), and were submitted to 1 week of 50% food restriction. The following parameters were evaluated: chemical carcass composition, protein and RNA content in liver and gastrocnemius muscle, and serum concentrations of insulin-like growth factor-1 and corticosterone. A higher liver weight and liver protein content were observed in the supplemented group (p < 0.05). However, no difference in body fat was found between groups (p > 0.05). The results indicate that low-dose leucine supplementation favors liver protein status but does not reduce body fat in rats during the early phase of rapid weight loss.
Gastrointestinal protective effect of dietary spices during ethanol-induced oxidant stress in experimental rats
Authors: Prakash Usha N.S. , Srinivasan Krishnapura
Published: April 2010

Spices are traditionally known to have digestive stimulant action and to cure digestive disorders. In this study, the protective effect of dietary spices with respect to activities of antioxidant enzymes in gastric and intestinal mucosa was examined. Groups of Wistar rats were fed for 8 weeks with diets containing black pepper (0.5%), piperine (0.02%), red pepper (3.0%), capsaicin (0.01%), and ginger (0.05%). All these spices significantly enhanced the activities of antioxidant enzymes — superoxide dismutase, catalase, glutathione reductase, and glutathione-S-transferase — in both gastric and intestinal mucosa, suggesting a gastrointestinal protective role for these spices. In a separate study, these dietary spices were found to alleviate the diminished activities of antioxidant enzymes in gastric and intestinal mucosa under conditions of ethanol-induced oxidative stress. The gastroprotective effect of the spices was also reflected in their positive effect on mucosal glycoproteins, thereby lowering mucosal injury. The amelioration of the ethanol-induced decrease in the activities of antioxidant enzymes in gastric and intestinal mucosa by dietary spices suggests their beneficial gastrointestinal protective role. This is the first report on the gastrointestinal protective potential of dietary spices.
Little change in markers of protein breakdown and oxidative stress in humans in immobilization-induced skeletal muscle atrophy
Authors: Glover Elisa I. , Yasuda Nobuo , Tarnopolsky Mark A. , Abadi Arkan , Phillips Stuart M.
Published: April 2010

A number of studies in rodents suggest that disuse atrophy results from a large increase in proteolysis affected by, or accompanying, increased oxidative stress. Little information is available, however, about the effects of immobilization on markers of muscle protein breakdown and oxidative stress in humans. Therefore, the purpose of this investigation was to measure markers of breakdown or oxidative stress in subjects who underwent 14 days of knee-brace-mediated immobilization. Vastus lateralis samples taken from 21 young subjects before, and 2 days and 14 days after, single leg immobilization were measured for ubiquitin-protein conjugates, caspase 3/7 activity, the 14-kDa caspase-3 cleaved actin fragment, 4-hydroxy-2-nonenal (4-HNE) adducts, and protein carbonyls. Quadriceps cross-sectional area decreased by 5.7% ± 1.1% (p < 0.0001) following immobilization. Ubiquitin-protein conjugates were elevated at 2 days of immobilization (12%, p < 0.05) but were not different from baseline at 14 days. Levels of the 14-kDa actin fragment and caspase 3/7 activity did not change over the immobilization period. The oxidative stress markers, 4-HNE adducts and protein carbonyls, did not change at any time point. These static measures of breakdown and oxidative modification suggest that a small increase in protein ubiquitination occurs early (2 days), but elevations in ubiquitinated or oxidatively modified proteins are not sustained during the later phase (14 days) of uncomplicated disuse atrophy in humans, suggesting that these pathways are not playing a major role in simple disuse-induced atrophic loss of protein mass.
Evaluation of exercise and potassium chloride supplementation on blood pressure and nociceptive threshold in hypertensive rats
Authors: Galdino Giovane S. , Lopes Airton M.C. , Franca Valéria M. , Duarte Igor D.G. , Perez Andrea C.
Published: April 2010

Hypertensive subjects present an increased nociceptive threshold, and the lack or delay of pain perception may impede detection of angina and myocardial infarction. Nutritional interventions, like potassium chloride (KCl) diet supplementation, and exercises are common nonpharmacological indications for treating hypertension. Spontaneous hypertensive rats (SHR) and normotensive male Wistar rats were submitted to a combination of exercise and KCl diet supplementation. Exercise reduced the nociceptive threshold in SHR; however, this effect was inhibited by KCl supplementation. Exercise and KCl supplementation did not alter systolic blood pressure. Reduction of the nociceptive threshold by exercise may be important for the detection of angina and myocardial infarction in hypertensive individuals.
Postexercise heart rate recovery in children: relationship with power output, blood pH, and lactate
Authors: Buchheit Martin , Duché Pascale , Laursen Paul B. , Ratel Sébastien
Published: April 2010

The aim of the present study was to determine whether differences in age-related heart rate recovery (HRR) kinetics were associated with differences in power output, blood lactate concentration ([La]b), and acidosis among children, adolescents, and adults. Ten prepubertal boys (aged 9.6 ± 0.7 years), 6 pubertal boys (aged 15.2 ± 0.8 years), and 7 men (aged 20.4 ± 1.0 years) performed 10 repeated 10-s all-out cycling sprints, interspersed with 5-min passive recovery intervals. Mean power output (MPO) was measured during each sprint, and HRR, [La]b, and acidosis (pHb) were determined immediately after each sprint. Children displayed a shorter time constant of the primary component of HRR than adolescents and adults (17.5 ± 4.1 vs. 38.0 ± 5.3 and 36.9 ± 4.9 s, p < 0.001 for both), but no difference was observed between adolescents and adults (p = 1.00). MPO, [La]b, and pHb were also lower in children compared with the other 2 groups (p < 0.001 for both). When data were pooled, HRR was significantly correlated with MPO (r = 0.48, p < 0.001), [La]b (r = 0.58, p < 0.001), and pHb (r = –0.60, p < 0.001). Covarying for MPO, [La]b, or pHb abolished the between-group differences in HRR (p = 0.42, p = 0.19, and p = 0.16, respectively). Anaerobic glycolytic contribution and power output explained a significant portion of the HRR variance following high-intensity intermittent exercise. The faster HRR kinetic observed in children appears to be related, at least in part, to their lower work rate and inherent lack of anaerobic metabolic capacity.
Nutrition inequities in Canada
Authors: Tarasuk Valerie , Fitzpatrick Sandra , Ward Heather
Published: April 2010

In Canada, increased morbidity and shorter life expectancy have been found among those with lower incomes and lower levels of education, but there has been little examination of socioeconomic variation in food and nutrient intake. Using data from the 2004 Canadian Community Health Survey, we examined the relationship between household income and education level and adults’ and children’s intakes of energy, fibre, micronutrients, and number of servings consumed of food groups from Canada’s Food Guide. To explore the public health significance of observed associations, we estimated the prevalence of inadequacy for selected nutrients for adults, stratifying by household income, education level, and sex. We found that a higher household income adequacy and (or) higher levels of education were associated with increased consumption of milk and alternatives, and vegetables and fruit, and significantly higher vitamin, mineral, and fibre intakes among both adults and children. The prevalence of inadequate nutrient intakes among adults was higher among adults with the lowest level of income adequacy or educational attainment, compared with others. Our results suggest that the nutritional quality of Canadians’ food intakes is, in part, a function of their social position. The impact of policy and program interventions needs to be examined across socioeconomic strata to ensure that actions reduce rather than exacerbate nutrition inequities.
The John Sutton memorial lecture, 2009. Conductance systems: an integrative approach to the physiology of extreme conditions
Authors: Shephard Roy J.
Published: April 2010

This presentation explores the value of mechanical, electrical, and mathematical analogues in understanding and evaluating a variety of closely integrated transport processes in human biology. Particular attention is directed to a major interest of John Sutton: the factors limiting transport of oxygen from the atmosphere to the working muscles when exercising in a variety of hostile environments. In most circumstances, the limiting term in a closely linked chain of conductances seems to be in the blood stream, and its magnitude can be estimated by measurements of maximal oxygen intake. Despite recent criticisms of this index by those who have proposed a feed-forward control of maximal aerobic effort, conductance theory suggests that the main limitation of oxygen transport is normally maximal cardiac output. Therefore, careful laboratory determinations of maximal oxygen intake continue to provide a convenient integrating assessment of an individual’s cardiorespiratory function, with many important applications in sports medicine and exercise science.
Policy directions to promote healthy dietary patterns in CanadaThis paper is one of a selection of papers published in the CSCN–CSNS 2009 Conference, entitled Are dietary patterns the best way to make nutrition recommendations for chronic disease prevention?
Authors: Tarasuk Valerie
Published: April 2010

The effective promotion of healthy dietary patterns rests on a supportive policy environment. Given the vast, ever-expanding selection of foods in Canadian supermarkets and the proliferation of nutrition-related food marketing, more effective communication tools are needed to help consumers understand food selections within the context of a total diet. In addition, policy actions at the federal, provincial, and municipal levels are needed to lift economic and geographic barriers to food access for specific population subgroups.
SCHEDULING SENSORS BY TILING LATTICES
Authors: KLAPPENECKER ANDREAS , LEE HYUNYOUNG , WELCH JENNIFER L.
Published: April 2010

Suppose that wirelessly communicating sensors are placed in a regular fashion on the points of a lattice. Common communication protocols allow the sensors to broadcast messages at arbitrary times, which can lead to problems should two sensors broadcast at the same time. It is shown that one can exploit a tiling of the lattice to derive a deterministic periodic schedule for the broadcast communication of sensors that is guaranteed to be collision-free. The proposed schedule is shown to be optimal in the number of time slots.
A MAXIMAL PREDICTABILITY PORTFOLIO SUBJECT TO A TURNOVER CONSTRAINT
Authors: TAKAYA YOSHIHIRO , KONNO HIROSHI
Published: April 2010

The authors demonstrated in earlier papers that a maximal predictability portfolio (MPP) using a dynamic strategy leads to a significantly better ex-post performance than the one based on a static strategy and the index. In this paper, we will consider a maximal predictability portfolio subject to transaction cost. To reduce transaction cost, we employ turnover constraint. It will be shown that this approach leads to a significantly better performance than the standard MPP and the index.
SAMPLE AVERAGE APPROXIMATION METHODS FOR A CLASS OF STOCHASTIC VARIATIONAL INEQUALITY PROBLEMS
Authors: XU HUIFU
Published: April 2010

In this paper we apply the well known sample average approximation (SAA) method to solve a class of stochastic variational inequality problems (SVIPs). We investigate the existence and convergence of a solution to the sample average approximated SVIP. Under some moderate conditions, we show that the sample average approximated SVIP has a solution with probability one and with probability approaching one exponentially fast with the increase of sample size, the solution converges to its true counterpart. Finally, we apply the existence and convergence results to SAA method for solving a class of stochastic nonlinear complementarity problems and stochastic programs with stochastic constraints.
A NONMONOTONE FILTER BARZILAI-BORWEIN METHOD FOR OPTIMIZATION
Authors: ZHANG YAN , SUN WENYU , QI LIQUN
Published: April 2010

In this paper we present a new globalization strategy of the Barzilai-Borwein gradient method for large scale unconstrained optimization. Based on the filter technique introduced by Fletcher and Leyffer, a modified Barzilai-Borwein method is presented. We prove the global convergence of this method. Extensive numerical results on a set of CUTEr test problems show that the proposed method is competitive.
IMPROVED PROJECTED GRADIENT ALGORITHMS FOR SINGLY LINEARLY CONSTRAINED QUADRATIC PROGRAMS SUBJECT TO LOWER AND UPPER BOUNDS
Authors: FU YUN-SHAN , DAI YU-HONG
Published: April 2010

In this paper, we consider the projected gradient algorithms for solving the quadratic program with bound constraints and a single linear equality constraint (SLBQP). We establish the relationship between the Lagrangian multiplier in the projection subproblem and the Lagrangian multiplier in the original optimization problem. Then we give an improved initial estimate of the Lagrangian multiplier in the subproblem based on this relationship. It appears that this initial estimate is very close to the optimal Lagrangian multiplier after several iterations of the outer loop. This will reduce at most 40% of the computing time in the projection subproblem. This initial guess can also be used in all kinds of projected gradient methods for solving the SLBQP problem. The numerical results show that it brings much more improvement in monotone algorithms than in nonmonotone algorithms. We also apply the adaptive steepest descent step-size and the Dai-Yuan step-size which are two monotone step-sizes to the projected gradient method of this SLBQP problem. Our numerical experiments showed that their performance can be better than some other monotone projected gradient methods.
GENERALIZED MEASURE OF UNCERTAINTY AND THE MAXIMIZABLE ENTROPY
Authors: OU CONGJIE , EL KAABOUCHI AZIZ , CHEN JINCAN , LE MÉHAUTÉ ALAIN , WANG ALEXANDRE QIUPING
Published: April 2010

For a random variable x we can define a variational relationship with practical physical meaning as [Formula: see text], where I is the uncertainty measure. With the help of a generalized definition of expectation, [Formula: see text], we can find the concrete forms of the maximizable entropies for any given probability distribution function, where g({pi}) may have different forms for different statistical methods which include the extensive and non-extensive statistics. Moreover, it is pointed out that this generalized uncertainty measure is valid not only for thermodynamic systems but also for non-thermodynamic systems.
THREE-DIMENSIONAL SIMULATION OF CONDENSED EXPLOSIVE-INDUCED FLOW PROPAGATION AND INTERACTION WITH GLASS CURTAIN WALL
Authors: DENG RONG-BING , JIN XIAN-LONG
Published: April 2010

In order to carry out blast response of curtain wall, the first step is to understand the complex flow of the air blasts around the structures and predict the blast loads acting on the structures. But in earlier studies related to blast resistant design of glass curtain wall, blast flow induced by condensed explosive is not taken into account due to expensively computational resources required. Based on high performance computing, this paper presents a new three-dimensional numerical simulation method of condensed explosive-induced flow propagation and impact on a complex glass curtain wall, where the fluid is represented by solving Navier–Stokes equations with a multimaterial arbitrary Lagrangian–Eulerian (ALE) formulation. In particular, the whole analytical model consists of condensed explosive, air, detailed curtain wall system, and ground, which comprehensively represents the real fluid–structure interaction environment. Final calculation has been performed on the Dawning 4000A supercomputer based on the domain decomposition method. The flow mechanisms of blast wave rounding curtain wall is visualized and the simulated pressure history of gauge is in good agreement with the experimental result which validates this method. The present method is shown to be a useful tool for blast resistance design of curtain wall in the future.
INFLUENCE OF MECHANICAL STRESS IN A MULTILAYER STRUCTURE ON SPATIAL DISTRIBUTION OF DOPANTS IN IMPLANTED-JUNCTION AND DIFFUSION-JUNCTION RECTIFIERS
Authors: PANKRATOV E. L.
Published: April 2010

The influence of mechanical stress in a multilayer structure on spatial distribution of dopants in implanted-junction and diffusion-junction rectifiers, which was produced in the structure has been analyzed. It is shown that the stress leads to additional reduction of spatial dimensions of the p–n junction in comparison with the reduction — a result of inhomogeneity — of the diffusion coefficient of dopant and other parameters of dopant redistribution (see, for example, Refs. 1–3).
COMPOSITION CONTROL AND ITS ELECTRICAL PROPERTIES OF TaNx THIN FILMS
Authors: JIANG H. C. , WANG C. J. , ZHANG W. L. , SI X.
Published: April 2010

TaN thin films were deposited on Al 2 O 3 wafers by DC reactive magnetron sputtering. The composition control by nitrogen partial flux in the working gas and the electrical properties of the samples were investigated in detail. The results show that the atomic number ratio of Ta to N in the samples can be adjusted from 4 to 0.88, corresponding to the contents of N in the samples from 20 at.% to 53 at.%, by adjusting the nitrogen partial flux from 2% to 6%. The main phases in the TaN x thin films are hexagonal Ta 2 N , body centered cubic Ta 10 N and face centered cubic TaN at lower N contents (lower than 28 at.%). However, at higher N contents (higher than 28 at.%), orthorhombic Ta 3 N 5 phase gradually precipitates out from the samples, and the hexagonal Ta 2 N phase disappears. When the N contents in the samples are lower than 28 at.%, the sheet resistance and resistivity of TaN x thin films are all low. With further increase of the N contents, the sheet resistance and resistivity of TaN x thin films increase sharply. The sheet resistance and the resistivity of the samples can be adjusted from 17 Ω/sq. to 77 Ω/sq., from 344 μΩ ·cm to 1030 μΩ ·cm by adjusting the nitrogen contents, respectively. When the nitrogen contents in the samples are lower than 28 at.%, the TCR of the samples is less than 50 ppm/°C. With further increase of N contents, the TCR of the samples increases sharply up to a few hundred ppm/°C.
AC CONDUCTIVITY AND DIELECTRIC PROPERTIES OF PMMA/FULLERENE COMPOSITES
Authors: NASR G. M. , AHMED R. M.
Published: April 2010

Dielectric properties and electrical conductivity of different concentrations of Poly methylmethacrylate (PMMA)/fullerene C60 composites have been reported at room temperature in the frequency range from 1 kHz to 5 MHz. The frequency dependence of complex permittivity, ε*, and complex electrical modulus, M*, have been measured. Frequency dependence of dielectric constant, follows Cole–Cole dielectric relaxation equations, was investigated diagrammatically. Moreover, equations of Tsangaris et al. have been tested for our case to describe the dielectric behavior of particulate polymeric composite containing fillers which give a satisfactory agreement taking into account the variation of the aspect ratio with the volume fraction of fullerene C60 doped in the PMMA matrix.
ALGEBRAIC APPROACH TO DYNAMICS OF MULTIVALUED NETWORKS
Authors: LI ZHIQIANG , CHENG DAIZHAN
Published: April 2010

Using semi-tensor product of matrices, a matrix expression for multivalued logic is proposed, where a logical variable is expressed as a vector, and a logical function is expressed as a multilinear mapping. Under this framework, the dynamics of a multivalued logical network is converted into a standard discrete-time linear system. Analyzing the network transition matrix, easily computable formulas are obtained to show (a) the number of equilibriums; (b) the numbers of cycles of different lengths; (c) transient period, the minimum time for all points to enter the set of attractors, respectively. A method to reconstruct the logical network from its network transition matrix is also presented. This approach can also be used to convert the dynamics of a multivalued control network into a discrete-time bilinear system. Then, the structure and the controllability of multivalued logical control networks are revealed.
INTERNAL RESONANCES AND BIFURCATIONS OF AN ARRAY BELOW THE FIRST PULL-IN INSTABILITY
Authors: GUTSCHMIDT STEFANIE , GOTTLIEB ODED
Published: April 2010

A nonlinear continuum model is used to investigate the dynamic behavior of an array of N nonlinearly coupled microbeams. Investigations concentrate on the region below the array's first pull-in instability, which is shown to be governed by several internal three-to-one and combination resonances. The nonlinear equations of motion for a two-element system are solved using the asymptotic multiple-scales method for the weak nonlinear system. The analytically obtained periodic response of two coupled microbeams is numerically evaluated by a continuation technique and complemented by a numerical analysis of a three-element array which exhibits quasi-periodic responses and lengthy chaotic transients. This study of small-size microbeam arrays serves for design purposes and the understanding of nonlinear nearest-neighbor interactions of medium- and large-size arrays.
BIFURCATION ANALYSIS OF THE 1D AND 2D GENERALIZED SWIFT–HOHENBERG EQUATION
Authors: GAO HONGJUN , XIAO QINGKUN
Published: April 2010

In this paper, bifurcation of the generalized Swift–Hohenberg equation is considered. We first study the bifurcation of the generalized Swift–Hohenberg equation in one spatial dimension with three kinds of boundary conditions. With the help of Liapunov–Schmidt reduction, the original equation is transformed to the reduced system, and then the bifurcation analysis is carried out. Secondly, bifurcation of the generalized Swift–Hohenberg equation in two spatial dimensions with periodic boundary conditions is also considered, using the perturbation method, asymptotic expressions of the nontrivial solutions bifurcated from the trivial solution are obtained. Moreover, the stability of the bifurcated solutions is discussed.
SIMPLE CONSERVATIVE, AUTONOMOUS, SECOND-ORDER CHAOTIC COMPLEX VARIABLE SYSTEMS
Authors: MARSHALL DELMAR , SPROTT J. C.
Published: April 2010

It is shown that, for analytic functions f, systems of the form [Formula: see text] and [Formula: see text] cannot produce chaos; and that systems of the form [Formula: see text] and [Formula: see text] are conservative. Eight simple chaotic systems of the form [Formula: see text] with quadratic and cubic polynomial f(z, z*) are given. Lyapunov spectra are calculated, and the systems' phase space trajectories are displayed. For each system, a Hamiltonian is given, if one exists.
SIMPLE MODELS FOR SCALING IN PHYLOGENETIC TREES
Authors: HERNÁNDEZ-GARCÍA EMILIO , TUĞRUL MURAT , ALEJANDRO HERRADA E. , EGUÍLUZ VÍCTOR M. , KLEMM KONSTANTIN
Published: April 2010

Many processes and models — in biological, physical, social, and other contexts — produce trees whose depth scales logarithmically with the number of leaves. Phylogenetic trees, describing the evolutionary relationships between biological species, are examples of trees for which such scaling is not observed. With this goal, we analyze numerically two branching models leading to nonlogarithmic scaling of the depth with the number of leaves. For Ford's alpha model, although a power-law scaling of the depth with tree size was established analytically, our numerical results illustrate that the asymptotic regime is approached only at very large tree sizes. We introduce here a new model, the activity model, showing analytically and numerically that it also displays a power-law scaling of the depth with tree size at a critical parameter value.
SIMULATION OF LARGE SCALE CORTICAL NETWORKS BY INDIVIDUAL NEURON DYNAMICS
Authors: SCHMIDT G. , ZAMORA-LÓPEZ G. , KURTHS J.
Published: April 2010

Understanding the functional dynamics of the mammalian brain is one of the central aims of modern neuroscience. Mathematical modeling and computational simulations of neural networks can help in this quest. In recent publications, a multilevel model has been presented to simulate the resting-state dynamics of the cortico-cortical connectivity of the mammalian brain. In the present work we investigate how much of the dynamical behavior of the multilevel model can be reproduced by a strongly simplified model. We find that replacing each cortical area by a single Rulkov map recreates the patterns of dynamical correlation of the multilevel model, while the outcome of other models and setups mainly depends on the local network properties, e.g. the input degree of each vertex. In general, we find that a simple simulation whose dynamics depends on the global topology of the whole network is far from trivial. A systematic analysis of different dynamical models and coupling setups is required.
STRUCTURAL ORGANIZATION OF FUNCTIONAL NETWORKS FROM EEG SIGNALS DURING MOTOR LEARNING TASKS
Authors: DE VICO FALLANI FABRIZIO , BALUCH FARHAN , ASTOLFI LAURA , SUBRAMANIAN DEVIKA , ZOURIDAKIS GEORGE , BABILONI FABIO
Published: April 2010

The evaluation of the topological properties of brain networks is an emerging research topic, since the estimated cerebral connectivity patterns often have relatively large size and complex structure. Since a graph is a mathematical representation of a network, the use of a theoretical graph approach would describe concisely the topological features of the functional network estimated from neuroimaging techniques. In particular, by applying the process of coherence analysis to high-density EEG recordings, rich visualizations can be developed that provide a means for spatiotemporal analysis of changes in synchronous brain activity. In the present work, we studied the changes in brain synchronization networks during performance of a complex visuomotor task with strategic components in normal subjects. In particular, we evaluated the differences in the functional network topology associated with human learning by calculating global and local efficiency indexes. Our results suggest that during an initial period of learning, which is probably related to the most significant cognitive processes, the particular organization of functional links in the alpha frequency band (8–12 Hz) tends to increase the efficiency of communication within the cerebral network. Such evidence could be interpreted as due to the need for a new strategy formulation. Overall, this approach enabled us to capture a shift in topology made during the process of learning and thus helped us to shed more light on the neural correlates of strategy formulation. Our findings provide strong support for the efficacy of theoretical graph analysis to study complex brain networks.
DISTRIBUTION OF DETRENDED STOCK MARKET DATA
Authors: LAN BOON LEONG , YEOH EE VON , NG JIN AUN
Published: April 2010

For stock market data, the empirical distribution of the return for stock price and the empirical distribution of the return for stock market index are well known. However, for the detrended data (defined as data divided by trend), which is a different fluctuating quantity compared to the return, only the distribution of detrended daily stock volume is known so far. In this paper, we show that for both stock price and stock market index, the detrended daily data is well fitted by a stable probability density with characteristic exponent parameter less than 2. The trend was modeled using either cubic smoothing spline or principal component analysis. The significance of our results for stock market modeling is discussed.
HOM-ALGEBRAS AND HOM-COALGEBRAS
Authors: MAKHLOUF ABDENACER , SILVESTROV SERGEI
Published: April 2010

The aim of this paper is to develop the theory of Hom-coalgebras and related structures. After reviewing some key constructions and examples of quasi-deformations of Lie algebras involving twisted derivations and giving rise to the class of quasi-Lie algebras incorporating Hom–Lie algebras, we describe the notion and some properties of Hom-algebras and provide examples. We introduce Hom-coalgebra structures, leading to the notions of Hom-bialgebra and Hom–Hopf algebras, and prove some fundamental properties and give examples. Finally, we define the concept of Hom–Lie admissible Hom-coalgebra and provide their classification based on subgroups of the symmetric group.
INVARIANTS OF DEFECTLESS IRREDUCIBLE POLYNOMIALS
Authors: BROWN RON , MERZEL JONATHAN L.
Published: April 2010

Defectless irreducible polynomials over a Henselian valued field (F, v) have been studied by means of strict systems of polynomial extensions and complete (also called "saturated") distinguished chains. Strong connections are developed here between these two approaches and applications made to both. In the tame case in which a root α of an irreducible polynomial f generates a tamely ramified extension of (F, v), simple formulas are given for the Krasner constant, the Brink separant and the diameter of f. In this case a (best possible) result is given showing that a sufficiently good approximation in an extension field K of F to a root of a defectless polynomial f over F guarantees the existence of an exact root of f in K. Also in the tame case a (best possible) result is given describing when a polynomial is sufficiently close to a defectless polynomial so as to guarantee that the roots of the two polynomials generate the same extension fields. Another application in the tame case gives a simple characterization of the minimal pairs (in the sense of N. Popescu et al.). A key technical result is a computation in the tame case of the Newton polygon of f(x+α). Invariants of defectless polynomials are discussed and the existence of defectless polynomials with given invariants is proven. Khanduja's characterization of the tame polynomials whose Krasner constants equal their diameters is generalized to arbitrary defectless polynomials. Much of the work described here will be seen not to require the hypothesis that (F, v) is Henselian.
MONOMIAL BASES FOR SOME IRREDUCIBLE 𝔤2-MODULES
Authors: LEE DONG-IL
Published: April 2010

We find relations for finite-dimensional irreducible representations of the simple Lie algebra 𝔤2, resulting in an explicit construction of Gröbner–Shirshov pairs and monomial bases for 𝔤2-modules V(nΛ2).
CHARACTER DEGREE SUMS AND REAL REPRESENTATIONS OF FINITE CLASSICAL GROUPS OF ODD CHARACTERISTIC
Authors: VINROOT C. RYAN
Published: April 2010

Let 𝔽q be a finite field with q elements, where q is the power of an odd prime, and let GSp (2n, 𝔽q) and GO ±(2n, 𝔽q) denote the symplectic and orthogonal groups of similitudes over 𝔽q, respectively. We prove that every real-valued irreducible character of GSp (2n, 𝔽q) or GO ±(2n, 𝔽q) is the character of a real representation, and we find the sum of the dimensions of the real representations of each of these groups. We also show that if G is a classical connected group defined over 𝔽q with connected center, with dimension d and rank r, then the sum of the degrees of the irreducible characters of G(𝔽q) is bounded above by (q + 1)(d+r)/2. Finally, we show that if G is any connected reductive group defined over 𝔽q, for any q, the sum of the degrees of the irreducible characters of G(𝔽q) is bounded below by q(d-r)/2(q - 1)r. We conjecture that this sum can always be bounded above by q(d-r)/2(q + 1)r.
LUSZTIG SYMMETRIES AND AUTOMORPHISMS OF QUANTUM SUPERALGEBRAS Uq(osp(1|2r))
Authors: CHEN XUEKUN , YANG SHILIN
Published: April 2010

We first construct algebra automorphisms Ti (1 ≤ i ≤ r) of ℤ2-graded Hopf algebra Uq( osp (1|2r)), which are called Lusztig's symmetries. It is shown that they satisfy braid group relations. The algebraic automorphisms of Uq( osp (1|2r)) are also described.
Checking in with Ben Bederson
Authors: Staff Ubiquity
Published: April 2010

By focusing on the user experience, the University of Maryland's Human-Computer Interaction Lab aims to improve lives through projects such as the International Children's Digital Library. Benjamin B. Bederson, interviewed here, is an Associate Professor of Computer Science and director of the Human-Computer Interaction Lab at the Institute for Advanced Computer Studies at the University of Maryland, College Park. His work is on information visualization, interaction strategies, and digital libraries.
Patterns for Success
Authors: Staff Ubiquity
Published: April 2010

Scott D. Anthony speaks about using innovation theory to transform organizations and create the next wave of growth. Anthony is a partner at Innosight, a management, consulting and education company located in Watertown, Massachusetts, and is co-author with Clayton M. Christensen and Erik A. Roth of the new book, "Seeing What's Next: Using the Theories of Innovation to Predict Industry Change."
Technologically Mediated Lifeworld
Authors: Tripathi Arun Kumar
Published: April 2010

Understanding the connection between science and technology is an essential step toward creating a more humane technoscience in the future.
An Interview with John Markoff
Authors: Ubiquity staff
Published: April 2010

John Markoff is author of the new best-seller "What the Dormouse Said: How the 60s Counterculture Shaped the Personal Computer Industry," and is a senior writer for The New York Times. His other books include "Cyberpunk: Outlaws and Hackers on the Computer Frontier" and "Takedown: The Pursuit and Capture of Kevin Mitnick, America's Most Wanted Computer Outlaw."
The cucumber season
Authors: Andersen Espen
Published: April 2010

Epsen Andersen asks, "How does the nature of information change when there is little of it?"
10 Things I've Learned About Teaching Online
Authors: Everson Michelle
Published: April 2010

Michelle Everson has been teaching online for five years. Here, she shares the top 10 best practices she has learned about online teaching.
Tips and Tools for Fostering a Creative e-Learning Class
Authors: Landay Susan
Published: April 2010

Despite the effectiveness of e-learning, online learners remain notorious for losing focus, getting bored, checking email, chatting, texting, sorting through piles of neglected mail, or tuning out altogether. It's not their fault. Trainers haven't equipped online learners with an arsenal of tools and toys that will help them stay focused. Here, we will look at some popular classroom methods of addressing the kinesthetic, visual, tactile, and interactive needs of learners, and explore some low cost ways to help online learners make the most of their remote learning experience.
Discussion Management Tips for Online Educators
Authors: Macek Jo
Published: April 2010

Jo Macek examines 10 best practices for managing class discussions in an online or virtual classroom.
E-Learning and Management Information Systems
Authors: El-Ghareeb Haitham A.
Published: April 2010

E-learning is the 'learning' process revolution enabled by new technologies that, hopefully, will present an effective and efficient learning process that doesn't exist today. Learning management systems (LMSs) are responsible for 'learning' activities, while university management information systems (UMISs) are responsible for handling University managerial activities. This article seeks to explain the differences between the two and how they are used.
E-Learning Tools for STEM
Authors: Andersen Maria H.
Published: April 2010

You'd think that instructors who teach math and hard sciences (or STEM fields) would be quick to pick up new technologies and be early adopters of e-learning. But in many of my interactions with administrators, what I actually hear is this: "Faculty from almost every discipline are interested in using new technologies and teaching online, except the people in math, science, and engineering." It's not that these faculty members don't want to teach online; it's that they can't see how to do it in their discipline. Here are six tools that are absolute necessities to get a math or hard sciences instructor teaching online successfully.
How Tiny Camcorders are Changing Education
Authors: Rowell Laurie
Published: April 2010

How effective are Flip cameras and other mini-camcorders as learning tools? Where are video-in-the-classroom assignment s taking education? Jake Dunagan, one of the tech prognosticators from the Institute for the Future, helps explain where video in the classroom will be going in coming years. Additionally, three intrepid instructors, who have been experimenting with mini-camcorders in their curricula, explain how they are using the technology and what their students are learning. These folks believe that using camcorders as a medium is affecting not only the message but the student communicators and their learning process.