bluuebunny/crossref_metadata_2025 huggingface dataset:
A Spherical DC Servo Motor With Three Degrees of Freedom
Authors: Kaneko K. , Yamada I. , Itao K.
Published: July 2009

A spherical DC servo motor with three degrees of freedom is proposed. First, the process of generating three-dimensional torque is analyzed to obtain the torque constant matrix. The matrix elements are shown to vary with rotor inclination, and winding currents are shown to interfere with each other. Then, the dynamics of the spherical motor are investigated theoretically and experimentally, considering torque interference, gyro moment and gravity. Finally, the trajectory of the prototype motor is shown in order to clarify its abilities. This new spherical motor is expected to produce a smaller, a lighter mechanism, since no gears or linkages are needed.
A Method for Modifying Dynamic Properties of Undamped Mechanical Systems
Authors: Tsuei Y. G. , Yee Eric K. L.
Published: July 2009

A method for the parametric study of the eigen frequencies and eigen vectors of a dynamic system is presented. The technique is based on the force response of the original dynamic system and gives a global picture for the behavior of the system with respect to the mass and stiffness parameters. It provides the sensitivity and feasibility of shifting the eigen frequency to a designed value; thus, it can be applied to the modal modification of a dynamic system. Because no iteration is required, the method is efficient.
On the Robot Compliant Motion Control
Authors: Kazerooni H.
Published: July 2009

The work presented here is a nonlinear approach for the control and stability analysis of manipulative systems in compliant maneuvers. Stability of the environment and the manipulator taken as a whole has been investigated using unstructured models for the dynamic behavior of the robot manipulator and the environment, and a bound for stable manipulation has been derived. We show that for stability of the robot, there must be some initial compliancy either in the robot or in the environment. The general stability condition has been extended to the particular case where the environment is very rigid in comparison with the robot stiffness. A fast, light-weight, active end-effector (a miniature robot) which can be attached to the end-point of large commercial robots has been designed and built to verify the control method. The device is a planar, five-bar linkage which is driven by two direct drive, brush-less DC motors. The control method makes the end-effector to behave dynamically as a two-dimensional, Remote Center Compliance (RCC).
PDF Subvariable Control and Its Application to Robot Motion Control
Authors: Leu M. C. , Freed D. I.
Published: July 2009

A method for determining the feedback coefficients of pseudo-derivative-feedback control is presented, along with applications of this control scheme. Simulations are performed for controlling a linear inertia system with disturbance loads and inertia variations, and for controlling a nonlinear system represented by a manipulator arm. The results show that PDF subvariable control quickly rejects disturbances and is insensitive to inertia variations. Also, the position responses do not exhibit overshoot or oscillation. Comparison with the results for proportional-plus-velocity-feedback control shows that the PDF approach is superior in response speed, robustness, and disturbance-handling ability. Experimental results from implementation of both control schemes to a revolute manipulator support this conclusion.
Nonlinear Response of Flexible Robotic Manipulators Performing Repetitive Tasks
Authors: Streit D. A. , Krousgrill C. M. , Bajaj A. K.
Published: July 2009

The dynamics of a flexible manipulator is described by two distinct types of variables, one describing the nominal motion and the other describing the compliant motion. For a manipulator programmed to perform repetitive tasks, the dynamical equations governing the compliant motion are parametrically excited. Nonlinear dynamics of a two-degree-of-freedom model is investigated in parameter regions where the nominal motion is predicted by the Floquet theory to be unstable. Multiple time scales technique is used to study the nonlinear response, and it is shown that the compliant coordinates can execute small but finite amplitude periodic motions. In one particular case, the amplitude of these periodic motions is shown to bifurcate to a periodic solution which subsequently undergoes period-doubling bifurcations leading to chaotic motions.
Interaction of Web Spans: Part I—Statics
Authors: Young G. E. , Shelton J. J. , Fang B.
Published: July 2009

When the friction between the web and a roller between two web spans is small enough that the tension distribution across the web in the downstream span affects the tension distribution in the upstream span interaction will occur. A model is developed which extends the work of one of the authors to this case and utilizes beam theory which is valid when the web is not in a wrinkled or slack edge state. The boundary conditions and static solutions for the three different types of interaction are established. In the circumferential slippage mode a negative steering effect has been identified. A steering effect description function is established which will allow prediction of this phenomenon which can be avoided by proper choice of system parameters.
Finite Element Modeling and Semiactive Control of Vibrations in Road Vehicles
Authors: Khulief Y. A. , Sun S. P.
Published: July 2009

Control of vibrations in lightweight road vehicle systems has placed increasingly higher demands on the technology required to accurately model and predict dynamic response of a vehicle system. In this paper, a method for modeling vehicles as systems of interconnected rigid and flexible bodies is presented. Finite element and component mode substitution techniques are employed to characterize elastic motions of flexible bodies in terms of minimal set of modal coordinates. Equations of motion and constraints of coupled system are written in terms of a set of reference and modal coordinates. Semiactive control techniques are then used for suppressing vibrations at some desired points, in the chassis, located away from suspension attachments. Remote measurement of local displacements and velocities at these points are used to implement a corrective control action into suspension dampers of adjustable damping characteristics. This method is applied to a planar vehicle model with flexible chassis traversing a bump. Numerical results demonstrate validity of the developed model and effectiveness of semiactive control in improving ride quality characteristics.
An Analytical and Experimental Study of the Dynamic Behavior of a Quick-Acting Hydraulic Fuse
Authors: Lee S. R. , Srinivasan K.
Published: July 2009

The dynamic behavior of a quick-acting hydraulic fuse is investigated here by analysis and experiment. The fuse has a very short response time and is designed to respond to pressure and flow transients that immediately follow a line rupture. In view of the short response time, a proper dynamic analysis of the entire hydraulic circuit is necessary, in addition to analysis of the fuse behavior. Dynamic models of the fuse and other hydraulic circuit elements used in the experimental setup are presented. The experiments consist of simulating line leaks and measuring fuse response, under a variety of operating conditions. Experimental and analytical results are in very good agreement if the leak transients are properly characterized.
A New Fluidic Oscillator, Flowmeter, Without Control Port and Feedback Loop
Authors: Shakouchi T.
Published: July 2009

The author has shown a new phenomenon. A three-dimensional, rectangular jet oscillates periodically when it is issued into a suddenly enlarged flow passage. A suitable configuration from the rectangular nozzle feature, a smaller height than the one the flow passage. Using this phenomenon, it is thought that a new fluidic oscillator, flowmeter, without control port and a feedback loop can be constructed. This paper makes clear the condition which causes the oscillation, depends on the relation between the oscillatory frequency and various conditions such as dimensions of the nozzle and flow passage of jet velocity. For the trial manufacture of the above-mentioned fluidic oscillator, the mechanism of oscillation and the oscillatory frequency was investigated.
Assessment of Transient Stability of Nonlinear Dynamic Systems by the Method of Tangent Hyperplanes and the Method of Tangent Hypersurfaces
Authors: Eskiciogˇlu A. M.
Published: July 2009

Two direct methods, the method of tangent hyperplanes and the method of tangent hypersurfaces, are applied to an elementary nonlinear dynamic system for transient stability assessment. The former method is based on the approximation of the asymptotic stability boundary by hyperplanes at a certain class of unstable singular points in the state-space, and the latter replaces hyperplanes by hypersurfaces. The applicability and accuracy of both methods are evaluated through a comparison of results.
Weld Pool Impedance for Pool Geometry Measurement: Stationary and Nonstationary Pools
Authors: Tam A. S. , Hardt D. E.
Published: July 2009

The most elusive quantity in describing weld pool geometry is the depth, since it cannot be directly observed; yet it is the most important quantity to be regulated during welding. This paper addresses the problem of depth feedback measurement for full penetration welds, where the objective is to completely melt the cross section. It has been demonstrated that the existence and size of a full penetration weld can be detected by measuring the mechanical impedance of the resulting weld pool. Previous work in modeling this phenomenon has been limited to stationary welds, and experiments have either used impractical measurement methods or have not provided conclusive results. In this paper, a model of pool motion is developed that applies to both the stationary and moving weld case, and the pool motion is detected directly from changes in the arc voltage. A description of pool motion is derived from an elliptical membrane model, and the total system transfer function, including arc and pool dynamics is derived. A series of experiments demonstrates that the pool motion can indeed be detected for the moving pool case. However, the exact determination of pool oscillation frequencies requires knowledge of the pool perimeter geometry, since the elliptical system has many closely spaced eigenvalues arising from both symmetric and antisymmetric mode shapes.
A New Lagrangian Formulation of Dynamics for Robot Manipulators
Authors: Li Chang-Jin
Published: July 2009

In this paper, a new Lagrangian formulation of dynamics for robot manipulators is developed. The formulation results in well structured form equations of motion for robot manipulators. The equations are an explicit set of closed form second order highly nonlinear and coupling differential equations, which can be used for both the design of the control system (or dynamic simulation) and the computation of the joint generalized forces/torques. The mathematical operations of the formulation are so few that it is possible to realize the computation of the Lagrangian dynamics for robot manipulators in real-time on a micro/mini-computer. For a robot manipulator with n degrees-of-freedom, the number of operations of the formulation is at most (6n2 + 107n − 81) multiplications and (4n2 + 102n − 86) additions; for n = 6, about 780 multiplications and 670 additions.
Positioning and Active Damping of Spring-Mass Systems
Authors: Vincent T. L. , Joshi S. P. , Lin Yeong Ching
Published: July 2009

In this paper, we investigate an alternate approach to the design of controllers for positioning and damping of a system which can be reduced to an equivalent system of springs and masses. The approach taken is to design a controller which uses open-loop positioning followed by closed-loop control for damping. By so doing, we can avoid a conflicting requirements problem associated with traditional state variable feedback design. The open-loop portion of the control is based on optimal control theory, which allows for control saturation. In particular, during this phase of the control, the time to position is minimized. This results in a bang-bang type of control. Once the system has been “positioned,” the controller switches to a closed-loop phase. The particular closed-loop control used here is based on energy methods and is not a full state variable feedback design. The method is illustrated using a low-order spring-mass example, and the results are compared with an LQ design.
Organocatalysis with azahelicenes: the first use of helically chiral pyridine-based catalysts in the asymmetric acyl transfer reaction
Authors: Šámal Michal , Míšek Jiří , Stará Irena G. , Starý Ivo
Published: July 2009

The successful utilisation of a helicene-based organocatalyst in acylative kinetic resolution of racemic secondary alcohol was described. Employing rac-1-phenylethanol, optically pure (–)-(M)-2-aza[6]helicene (5–20 mole %), isobutyric anhydride and N-ethyldiisopropylamine in chloroform at 22–40 °C, an asymmetric acyl transfer reaction took place overwhelming the uncatalysed background process. Moderate reactivity as well as selectivity factor (s = 9, 10) were observed. An effective control of the enantiodiscriminating step in acylative kinetic resolution by the helically chiral organocatalyst was proven for the first time.
Public health implications of establishing a national programme to screen young athletes in the UK
Authors: Elston Julian , Stein Ken
Published: July 2009

Objectives

To assess how much competitive sport contributes to sudden cardiac death (SCD) in young athletes and the impact on population health if this group were to be screened in the UK.

Methods

Using reported and imputed incidence rates of SCD in athletes and non-athletes and false-negative and false-positive test rates reported in three key Italian screening studies, the authors calculated the population and attributable risk fractions of SCD in young athletes and the total population (athletes and non-athletes) aged 12–35 years before and after screening; the number of athletes needed to screen (NNS) to prevent one SCD and the sensitivity and the specificity of screening with electrocardiogram. Using these parameters, the authors developed a decision tree model based on the UK population aged 12–35 years to estimate the annual number of SCDs, the expected number of screening and diagnostic tests and the number of athletes disqualified from competitive sport per SCD prevented.

Results

Participation in competitive athletics contributes to 81.9% (62.4% to 91.6%) of SCD in athletes but only 26.6% (−20.3% to 55.8%) in the total population. After screening, the contribution in the total population falls to 7.2% (−10.7% to 22.4%). The NNS is 38 151 (20 534 to 267 380). A UK screening programme would result in 1 520 021 young athletes being screened, with 140 361 referred for diagnosis. Of an expected 196 SCDs per year, 40 (6 to 74) would be prevented. For every life saved, 791 athletes would be disqualified.

Conclusions

The impact of screening on reducing SCD in young athletes is only modest and would be achieved with significant harms to population health.
Throwing workload and injury risk in elite cricketers
Authors: Saw Richard , Dennis Rebecca J , Bentley David , Farhart Patrick
Published: July 2009

Objective

To investigate the risk between throwing workload and upper limb injury in elite cricketers.

Design

Prospective cohort study.

Setting

Elite Australian cricket.

Participants

28 adult male cricketers aged 18–32 years.

Assessment of risk factors

Daily throwing workload and injury were prospectively monitored over the 2007–2008 cricket season. Risk ratios (RRs) were calculated to describe the association between throwing workload and injury.

Main outcome measurement

Upper limb injury associated with throwing.

Results

Seven (25%) players sustained an injury during the season. Injured players threw approximately 40 more throws/week (p=0.004) and 12.5 more throws per throwing day (p=0.061) than uninjured players. Players were at a significantly increased risk of injury if they completed more than 75 throws/week (RR=1.73, 95% CI=1.03 to 2.92), and there was a trend towards an increased risk if they completed more than 40 throws per throwing day (RR=1.41, 95% CI=0.88 to 2.26). Injured players also completed more throws and had more throwing days (and consequently less rest days) in the week before injury, as compared with the rest of their season preceding that point.

Conclusion

An increased throwing workload is a risk factor for the development of upper limb injury in elite cricketers. Investigation of the kinematics of throwing in elite cricketers would complement this study, and further research is required to develop detailed throwing workload guidelines for cricketers across a range of ages.
Expression of the forkhead box transcription factor FOXP1 is associated with oestrogen receptor alpha, oestrogen receptor beta and improved survival in familial breast cancers
Authors: Rayoo M , Yan M , Takano E A , Bates G J , Brown P J , Banham A H , Fox S B
Published: July 2009

Background:

The role of FOXP1 in sporadic breast cancers has been widely studied but its role in familial breast cancers is yet unexplored.

Aims:

To investigate FOXP1 expression in different molecular subtypes of familial breast cancers and to correlate its expression with clinicopathological parameters, oestrogen receptors (ER) and survival.

Methods:

Immunohistochemical staining for FOXP1 was performed in 126 familial breast carcinomas comprising 35 BRCA1, 34 BRCA2 and 57 BRCAX.

Results:

Nuclear FOXP1 expression ranged from focal weak to widespread strong expression. Expression of FOXP1 was higher in familial breast cancers (54%) compared with sporadic cancers (46%) (p<0.001). There was a significant correlation between FOXP1 with ERα (p = 0.038) and ERβ (p = 0.007) in familial breast cancers. FOXP1 was more highly expressed in familial breast cancers compared with sporadic cancers for luminal (p = 0.021) and basal (p<0.001), but not HER2 and null phenotypes (both p>0.05). The absence of FOXP1 expression was associated with a shorter relapse-free (p = 0.025) and overall survival (p = 0.009) in familial breast cancer. Negativity for FOXP1 was associated with a significantly worse overall survival in BRCA2 cancers (p = 0.021) and there was a non-significant separation of the survival curves for BRCA1 cancers (p = 0.183). No differences in survival were seen for BRCAX cancers (p = 0.762).

Conclusion:

Results suggest that FOXP1 demonstrates different expression patterns in familial breast cancers than sporadic tumours, even in tumours showing similar phenotypes. They also suggest a different role of FOXP1 as a tumour suppressor in familial tumours, which is unrelated to ER expression and may impact on therapeutic options.
Special communication: China’s first historic efforts to develop a tobacco control advocacy workforce via schools of public health
Authors: Yang T , Yang X , Lv Q , Zhao Q , Ke X
Published: July 2009

This paper provides an overview of a recent 18-month project which set out for the first time to introduce training on tobacco control into the curricula of public health courses in Chinese universities. The aim was to produce graduates with appropriate knowledge and skills to be effective in advocating for policies that could lead to the reduction of tobacco use. Results from this initial project involving seven universities have been encouraging and the new curriculum is to be implemented, with some changes, on a wider scale throughout China. Each of the universities also successfully introduced a smoke-free campus policy and the aim is to extend this policy.
MASSLESS SCALAR FREE FIELD IN 1+1 DIMENSIONS I: WEYL ALGEBRAS PRODUCTS AND SUPERSELECTION SECTORS
Authors: CIOLLI FABIO
Published: July 2009

This is the first of two papers on the superselection sectors of the conformal model in the title, in a time zero formulation. A classification of the sectors of the net of observables as restrictions of solitonic (twisted) and non-solitonic (untwisted) sector automorphisms of proper extensions of the observable net is given. All of them are implemented by the elements of a field net in a non-regular vacuum representation and the existence of a global compact Abelian gauge group is proved. A non-trivial center in the fixed-point net of this gauge group appears, but in an unphysical representation and reducing to the identity in the physical one. The completeness of the described superselection structure, to which the second paper is devoted, is shown in terms of Roberts' net cohomology. Some general features of physical field models defined by twisted cross products of Weyl algebras in non-regular representations are also presented.
FORECASTING FORWARD EXCHANGE RATE RISK PREMIUM IN SINGAPORE DOLLAR/US DOLLAR EXCHANGE RATE MARKET
Authors: KIANI KHURSHID M.
Published: July 2009

In this research, monthly forward exchange rates are evaluated for possible existence of time varying risk premia in Singapore forward foreign exchange rates against US dollar. The time varying risk premia in Singapore dollar is modeled using non-Gaussian signal plus noise models that encompass non-normality and time varying volatility.

The results from signal plus noise models show statistically significant evidence of time varying risk premium in Singapore forward exchange rates although we failed to reject the hypotheses of no risk premium in the series. The results from Gaussian versions of these models are not much different and are in line with Wolff (1987) who also used the same methodology in Gaussian settings.

Our results show statistically significant evidence of volatility clustering in Singapore forward exchange rates. The results from Gaussian signal plus noise models also show statistically significant evidence of volatility clustering and non-normality in Singapore forward foreign exchange rates. Additional tests on the series show that exclusion of conditional heteroskedasticity from the signal plus noise models leads to false statistical inferences.
INDETERMINACY IN A ONE-SECTOR MODEL REVISITED: DEMAND VERSUS SUPPLY-SIDE INDETERMINACY
Authors: SIM NICHOLAS C. S.
Published: July 2009

This paper explains how indeterminacy in a one-sector model may arise due to externalities in the disutility of labor supply, which is termed as demand-side indeterminacy. This contrasts supply-side indeterminacy that is driven by externalities in the production function as exemplified by Benhabib and Farmer (Journal of Economic Theory, 1994). For the one-sector models considered, I find that indeterminacy arises more easily from the demand than from the supply side. In addition, demand and supply-side indeterminacy generate different cyclical patterns of wages, a feature that is useful for identifying episodes of self-fulfilling prophecies within the two types of indeterminacy.
A SIMPLE ALGORITHM FOR THE BASIC (R, Q) INVENTORY CONTROL MODEL WITH RETURN FLOW
Authors: OUYANG HUIQING , ZHU XIANGYANG
Published: July 2009

In recent years, as a result of environmental legislation and an increasing interest in economics, many producers have been forced to implement the PTB (Products Tack Back) program. In this paper, we employ the basic (R, Q) model to control a single-item single-echelon inventory system with return flow. Based on the assumption that the return and the demand are independent Poisson processes, we derive a simple approximate algorithm to determine the optimal control parameters. The numerical examples show that the presented algorithm is more tractable than the exact algorithm and more accurate than other approximate algorithms, such as normal approximation.
CONSISTENCY TEST OF DARK ENERGY MODELS
Authors: CHEN CHIEN-WEN , GU JE-AN , CHEN PISIN
Published: July 2009

Recently we proposed a new approach to test dark energy models based on the observational data. In that work we focused particularly on quintessence models for demonstration and invoked a widely used parametrization of the dark energy equation of state. In this paper we take the more recent SN Ia , CMB and BAO data, invoke the same parametrization, and apply this method of consistency test to five dark energy models, including the ΛCDM model, the generalized Chaplygin gas, and three quintessence models: exponential, power-law and inverse-exponential potentials. We find that the exponential potential of quintessence is ruled out at the 95.4% confidence level, while the other four models are consistent with data. This consistency test can be efficiently performed since for all models it requires the constraint of only a single parameter space that by choice can be easily accessed.
UNUSUAL HIGGS OR SUPERSYMMETRY FROM NATURAL ELECTROWEAK SYMMETRY BREAKING
Authors: DERMÍŠEK RADOVAN
Published: July 2009

This review provides an elementary discussion of electroweak symmetry breaking in the minimal and the next-to-minimal supersymmetric models with the focus on the fine-tuning problem — the tension between natural electroweak symmetry breaking and the direct search limit on the Higgs boson mass. Two generic solutions of the fine-tuning problem are discussed in detail: models with unusual Higgs decays; and models with unusual pattern of soft supersymmetry breaking parameters.
STRONG MODE TRANSFORMATION OF ELASTIC WAVES BY SPHERICAL SOLID OBJECT
Authors: ZHANG XIN , WU FUGEN
Published: July 2009

We investigate mode transformation between longitudinal mode and transverse mode by spherical solid object. By analyzing the scattering cross section, we find that longitudinal wave (L) transformation to transverse wave (T) is much more than transverse wave (T) transformation to longitudinal wave (L). The ratio of L → T converted waves to T → L converted waves is verified to be independent of frequency. The strongest mode transformation between transverse mode and longitudinal mode can be obtained by choosing a solid sphere with large density and low shear velocity and background with small density and high shear velocity.
OPTIMAL BOUNDS ON DISPERSION COEFFICIENT IN ONE-DIMENSIONAL PERIODIC MEDIA
Authors: CONCA CARLOS , MARTÍN JORGE SAN , SMARANDA LOREDANA , VANNINATHAN MUTHUSAMY
Published: July 2009

In this paper, we consider the macroscopic quantity, namely the dispersion tensor associated with a periodic structure in one dimension (see Refs. 5 and 7). We describe the set in which this quantity lies, as the microstructure varies preserving the volume fraction.
PATTERN FORMATION IN A RING NETWORK WITH DELAY
Authors: GUO SHANGJIANG , YUAN YUAN
Published: July 2009

We consider a ring network of three identical neurons with delayed feedback. Regarding the coupling coefficients as bifurcation parameters, we obtain codimension one bifurcation (including a Fold bifurcation and Hopf bifurcation) and codimension two bifurcations (including Fold–Fold bifurcations, Fold–Hopf bifurcations and Hopf–Hopf bifurcations). We also give concrete formulas for the normal form coefficients derived via the center manifold reduction that provide detailed information about the bifurcation and stability of various bifurcated solutions. In particular, we obtain stable or unstable equilibria, periodic solutions, and quasi-periodic solutions.
OPTICAL ANGULAR MANIPULATION OF LIQUID CRYSTAL DROPLETS IN LASER TWEEZERS
Authors: BRASSELET E. , JUODKAZIS S.
Published: July 2009

The high sensitivity of liquid crystals to external fields, especially electromagnetic fields, confer to them fascinating properties. In the case of light fields, their large optical nonlinearities over a broad spectrum have great application potential for all-optical devices. The linear optical properties of liquid crystals, such as their high refractive index, birefringence and transparency, are also of great practical interest in optofluidics, which combines the use of optical tools in microfluidic environments. A representative example is the laser micromanipulation of liquid crystalline systems using optical tweezing techniques. Liquid crystal droplets represent a class of systems that can be easily prepared and manipulated by light, with or without a nonlinear light-matter coupling. Here we review different aspects of quasi-statics and dynamical optical angular manipulation of liquid crystal droplets trapped in laser tweezers. In particular, we discuss to the influence of the phase (nematic, cholesteric or smectic), the bulk ordering symmetry, the droplet size, the polarization state and power of the trapping light, together with the prominent role of light–matter angular momentum exchanges and optical orientational nonlinearities.
DARK SOLITON SOLUTIONS TO THE NONLINEAR SCHRÖDINGER EQUATION FOR ULTRASHORT PULSE PROPAGATION IN METAMATERIALS
Authors: CHENG XI , ZHUANG BINXIAN , DAI XIAOYU , SU WENHUA , WEN SHUANGCHUN
Published: July 2009

The nonlinear Schrödinger equation for ultrashort pulse propagation in metamaterials with a nonlinear polarization is solved by an extended tanh function expansion method, and the dark solitary wave solutions for various conditions are obtained. The role of the dispersive magnetic permeability, which manifests itself as self-steepening and higher order nonlinear dispersion terms in the nonlinear Schrödinger equation in dark solitary wave propagation, is identified. It is found that the negative self-steepening effect in metamaterials makes the solitary wave move to the leading side, opposite to that in ordinary materials, in which the self-steepening effect is always positive. Most importantly, due to the role of the second order nonlinear dispersion, dark solitons can be formed in the absence of linear dispersion, or even in the case of anomalous linear group velocity dispersion, different from the conditions for dark soliton formation in ordinary materials.
THRESHOLD REDUCTION OF STIMULATED BRILLOUIN SCATTERING BY ENHANCING INITIAL BRILLOUIN ULTRASOUNDS
Authors: ZHU YONGXIANG , LU QISHENG , GUO SHAOFENG , CHENG XIANG'AI
Published: July 2009

We propose reducing the threshold of stimulated Brillouin Scattering by enhancing the initial Brillouin ultrasounds, since the high threshold results from the low intensity of the sounds that exist in thermal noises. Theoretical analysis shows that the threshold can be reduced by at least one order through introducing comparatively weak Brillouin ultrasounds. Schemes for enhancing the initial ultrasounds are also proposed, including stimulation by transducers, by electroacoustic media or by direct radiation of microwaves.
EXISTENCE OF SOLUTIONS AND ITERATIVE APPROXIMATIONS FOR NONLINEAR SYSTEMS ARISING IN FREE CONVECTION
Authors: BRIGHI BERNARD , GUESMIA SENOUSSI
Published: July 2009

We study the existence and the regularity of the solutions of some nonlinear partial differential system arising in the study of free convection in a two-dimensional bounded domain, modeling a porous medium saturated with a fluid. By introducing an iterative method, the closeness of such solutions by solution of linear elliptic problems is given with an exponential rate of convergence.
SVM LEARNING AND Lp APPROXIMATION BY GAUSSIANS ON RIEMANNIAN MANIFOLDS
Authors: YE GUI-BO , ZHOU DING-XUAN
Published: July 2009

We confirm by the multi-Gaussian support vector machine (SVM) classification that the information of the intrinsic dimension of Riemannian manifolds can be used to illustrate the efficiency (learning rates) of learning algorithms. We study an approximation scheme realized by convolution operators involving the Gaussian kernels with flexible variances. The essential analysis lies in the study of its approximation order in Lp (1 ≤ p < ∞) norm as the variance of the Gaussian tends to zero. It is different from the analysis for approximation in C(X) since pointwise estimations do not work any more. The Lp approximation arises from the SVM case where the approximated function is the Bayes rule and is not continuous, in general. The approximation error is estimated by imposing a regularity condition that the approximated function lies in some interpolation spaces. Then, the learning rates for multi-Gaussian regularized classifiers with general classification loss functions are derived, and the rates depend on the intrinsic dimension of the Riemannian manifold instead of the dimension of the underlying Euclidean space. Here, the input space is assumed to be a connected compact C∞ Riemannian submanifold of ℝn. The uniform normal neighborhoods of the Riemannian manifold and the radial basis form of Gaussian kernels play an important role.
A NOTE ON THE SPECTRUM OF BI-INFINITE BI-DIAGONAL RANDOM MATRICES
Authors: LINDNER MARKO
Published: July 2009

The purpose of this paper is to demonstrate the use of the results from [5, 6] for the explicit computation of the spectrum of two-sided infinite matrices with random diagonals. Here we consider the case of two random diagonals, one of them the main diagonal. Our result is a generalization of [24, Theorem 8.1] by Trefethen, Contedini and Embree from the case of one random and one constant diagonal to the case of two random diagonals.
A Methodological Examination of MIS Survey Research from 1992–2006
Authors: Abareshi Ahmad , Martin Bill
Published: July 2009

It would be useful for IS researchers to know the major methodological methods used in IS filed and the trends MIS is experiencing in this regard. For this reason, we have conducted a meta-research on three leading IS journals over a period of 15 years in an attempt to provide the MIS field with an overview of research methodologies used and help researchers in choosing appropriate research method. 651 survey-based studies reported in three leading MIS journals between 1992 and 2006 are reviewed. The findings indicate that a considerable proportion of MIS research has been conducted using the survey method. In terms of research purpose, there has been an imbalance between the use of exploratory and explanatory surveys. Consequently, it is to be expected that in the immediate future, the trend will be much more towards the development of models and the explanation of relationships that is towards explanatory studies.
Design of an Ontology as a Support to the Knowledge Audit Process in Organisations
Authors: Perez-Soltero Alonso , Barcelo-Valenzuela Mario , Sanchez-Schmitz Gerardo
Published: July 2009

The objective of this article is to show an ontology that can serve as support to represent the results obtained throughout the knowledge audit process in organisations. This paper describes the form to represent what was obtained throughout the audit process and its advantages, as well as the mechanism to reuse the information gathered from it. The design of the proposed ontology, the elements to be presented from knowledge audit, the way in which they can be represented with the help of the ontology, and their potential reuse for the development of applications are shown.
The Successful Implementation of Knowledge Management Processes: The Role of Human Resource Systems "An Empirical Study in the Jordanian Mobile Telecommunication Companies"
Authors: Alhawary Faleh Abdelgader , Al-Zegaier Hanadi
Published: July 2009

Knowledge is a resource that is valuable to an organisation's ability to innovate and compete. It exists within the individual employees, and also in a composite sense within the organisation. Therefore, it is important that organisations find a way to tap into this knowledge and effectively manage knowledge processes in order to preserve and expand its core competencies to maintain a sustainable competitive advantage. The purpose of this study is to examine the impact of human resource systems (HR planning System, HR Training System, HR Reward System, HR recruitment System) on the successful implementation of knowledge management processes (acquisition, application, sharing). Respondents consist of top/senior managers, human resource managers, and heads of departments in the Jordanian mobile telecommunication companies. A questionnaire survey was developed to collect data from respondents, a sample of 150 were selected according to a simple random sampling technique. Different statistical tools were used to test study hypotheses. The study findings shows that overall human resource systems have a significant impact on knowledge management processes. Based on the findings, the study suggest future research which can seek an enhanced understanding of the relationship of HRS with knowledge management processes in other sectors and other countries as well, since cultural differences exist among organisations, which influence employee perceptions regarding knowledge management processes. This study has implications for HR managers or decision-makers to create an organisational environment that encourages employee empowerment, integration and socialisation by eliminating all forms of barriers and red tapes, which can allow people to participate for new opportunities and foster a positive social interaction culture before introducing knowledge management initiatives.
ADVANCES IN F0F1-ATP SYNTHASE BIOLOGICAL PROTEIN NANOMOTOR: FROM MECHANISMS AND STRATEGIES TO POTENTIAL APPLICATIONS
Authors: KHATAEE H. R. , KHATAEE A. R.
Published: July 2009

Movement and shape changes are fundamental aspects of all living organisms. This biological motility results from the biological nanomotors, in particular protein nanomotors. Cells contain a variety of protein nanomotors that rotate (e.g., F0F1-ATP synthase or bacterial flagellar motors) or move in a linear fashion (e.g., the kinesin, myosin and dynein motors). F0F1-ATP synthase is one of the ideal nanomotors or energy providing systems for micro/nanomachines because of its small size, smart and perfect structure, and ultra-high energy transfer efficiency. Therefore, in this paper, we have reviewed the structure, mechanism, and potential applications of the F0F1-ATP synthase nanomotor. In all organisms, the F0F1-ATP synthase consists of two distinct nanomotors, F0and F1. The F0moiety is embedded in the membrane and is a detergent soluble unit while the F1moiety protrudes from the membrane and is a water soluble unit. F0F1-ATP synthase operates as two stepper motor/generators coupled by a common shaft and an electrochemical-to-mechanical-to-chemical energy transducer with an astounding 360° rotary motion of subunits. F0F1-ATP synthase nanomotor may enable the creation of a new class of sensors, mechanical force transducers, actuators, and nanomechanical devices. Thus, the F0F1-ATP synthase nanomotor field has expanded into a wide variety of science.
FUNCTIONALITY OF BARE NITINOL SURFACES
Authors: SHABALOVSKAYA SVETLANA , UNDISZ ANDREAS , RETTENMAYR MARKUS , RONDELLI GIANNI
Published: July 2009

The results of pilot in situ studies of the responses of Nitinol surfaces to deformation are presented. It is shown that the mechanical behavior of Nitinol surfaces differs, depending on oxide thickness and its chemical composition. The corrosion resistance of the surfaces evaluated in strain-free and strained states using potentiodynamic and potentiostatic cyclic polarization at the body potentials demonstrated quite stable behavior.
The limitations of Quaternary lithostratigraphy: an example from southern Ireland
Authors: Knight Jasper
Published: July 2009

The lithostratigraphy of Quaternary extra-glacial (cold-climate) sediments is described from five sites along the south coast of Ireland. These sediments are compared to a regional-scale lithostratigraphic framework. This comparison enables consideration of the applicability of standard lithostratigraphic principles and practices to the Quaternary record. It is concluded that a strict lithostratigraphic approach is not favourable towards interpreting the age or depositional process/environment of Quaternary sediments, either in isolation or as part of a sedimentary succession. The concepts of time transgression and lateral equivalence are useful interpretive tools that can support lithostratigraphic procedures as applied to the Quaternary record.
Geotechnical controls on a steep lateral moraine undergoing paraglacial slope adjustment
Authors: Curry Alastair M. , Sands Tim B. , Porter Philip R.
Published: July 2009

Sustained post ‘Little Ice Age’ retreat of the northern lobe of the Feegletscher, Valais, Switzerland, has exposed lateral moraines that show pronounced oversteepening on the upper proximal slopes, with upper-slope segments displaying angles of up to about 70°. Paraglacial processes have eroded gullies into the upper-slope segments, and associated debris-flow deposits result in lower angles of between 34° and 25° in the mid-slope and slope-foot zones, respectively. In order to assess the geotechnical properties of morainic sediments that permit development of quasi-stable, oversteepened slope segments, a standard suite of geotechnical measures was applied to samples of Feegletscher moraine sediments. Shear box testing yielded angles of friction ranging from 35° for loose samples to 52° for dense samples. Although the heterogeneous nature of moraine deposits makes laboratory testing of the whole size range of
in situ
sediments impractical, shear box test results imply that
in situ
upper-slope angles exceed the angles of friction of moraine sediments by 26°–40°. We are unable to replicate angles of friction in shear box tests that correspond to
in situ
angles of the upper-slope sections measured in the field. However, we suggest that distal dipping mica-schist clasts may play an important role in permitting high-angle slope stability. Quasi-stable storage of glacigenic sediments in high-angle moraine sequences over decadal timescales has implications for understanding the period following deglaciation over which paraglacial reworking and redistribution of sediments may operate.
Paraglacial geomorphology of Quaternary volcanic landscapes in the southern Coast Mountains, British Columbia
Authors: Friele Pierre A. , Clague John J.
Published: July 2009

An important paradigm in geomorphology is
paraglacial sedimentation
, a phrase first used almost 40 years ago to describe reworking of glacial sediment by mass wasting and streams during and after continental-scale deglaciation. The concept has been extended to include non-glacial landforms and landscapes conditioned by glaciation. In this paper we apply the paraglacial concept to volcanoes in southern British Columbia, Canada, that formed, in part, in contact with glacier ice. The Cheekye River basin, a small watershed on the flank of a volcano that erupted against the decaying Cordilleran ice sheet, has a Holocene history marked by an exponential decay in debris-flow activity and sediment yield. Its history is consistent with the primary exhaustion model of the paraglacial cycle. At larger spatial scales, this primary sediment is reworked by rivers and transported downstream and augmented by stochastic geomorphic events. Repeated large landslides from Mount Meager volcano in southern British Columbia have delivered a disproportionate volume of sediment to the fluvial system: although occupying only 2% of the watershed area, 25–75% of the 10 km
3
of sediment deposited in Lillooet River valley during the Holocene originated from the volcano. In these cases a significant overall reduction in sediment yield must await the removal, by erosion, of volcanic edifices, a process that could take up to millions of years. These examples of paraglacial activity on Quaternary volcanoes are end members in the spectrum of landscape response to Pleistocene deglaciation.
Climate sensitivity: implications for the response of geomorphological systems to future climate change
Authors: Harrison Stephan
Published: July 2009

Climate sensitivity is defined as the equilibrium temperature response of the climate system to a doubling of atmospheric CO
2
levels from pre-industrial levels. Despite three decades of debate in the climatological literature on the estimation and significance of climate sensitivity, very little appears in the geomorphological literature on the implications of this for geomorphological systems. This paper reviews the concept of climate sensitivity and applies its findings to an assessment of future landscape change in cold regions. It is concluded that paraglacial processes will become the dominant mechanism of sediment transfer in currently glaciated catchments and that this period of sediment mobilization will be the last episode of major sediment movement for geological time periods.
Holocene microweathering rates and processes on ice-eroded bedrock, Røldal area, Hardangervidda, southern Norway
Authors: Nicholson Dawn T.
Published: July 2009

Post-glacial weathering of ice-eroded metamorphic bedrock was investigated in the Røldal area (60°N) of the Hardangervidda Plateau in southern Norway. Quartz veins were used as reference surfaces to determine a mean post-glacial surface lowering rate of 0.55 mm ka
−1
. Chemical characteristics of late-season runoff were determined for one catchment (Snøskar) and a chemical erosion rate of 4.9 t km
−2
a
−1
was obtained. A mean
in situ
fracture enlargement due to microweathering of 0.12 mm ka
−1
was also determined. These rates are low, although comparable with similar environments in cold regions, and suggest that microweathering has had relatively little impact on Holocene landscape evolution. Weathering rind thickness was found to be less on fracture walls than on exposed bedrock surfaces, suggesting fractures have not played a significant role in microweathering. Observations of weathering morphology reveal a range of forms including shallow spalling, tafoni and pseudokarren, indicating locally intense weathering activity. Analysis of interrelationships between multiple weathering indices points to the importance of bedrock microweathering as a precursor to macro-breakdown and landform evolution. The research reasserts the importance of chemical activity in cold environments and the importance of moisture supply for effective microweathering.
The role of buoyancy in palsa formation
Authors: Seppälä Matti , Kujala Kauko
Published: July 2009

The formation of a palsa is based on the thermal properties of peat. Frozen wet peat has a high thermal conductivity, and therefore cold can penetrate deep into peat layers if the snow cover is thin; while the dry peat in summer insulates the frozen core of a palsa, so that the permafrost core is preserved. The volumetric growth of the palsa is based on the buoyancy effect of the frozen core, which lifts it, causing some water to accumulate under the core, where it freezes during the next winter and forms thin ice layers. Only when the frozen peat core touches the frost-susceptible silt or silty till layer at the bottom of the mire does ice segregation start to play an important role in the formation of the palsa.
Navigating Between the Scylla and Charybdis of Prescribing Dietary Protein for Chronic Kidney Diseases
Authors: Franch Harold A. , Mitch William E.
Published: July 2009

A fundamental clinical problem in treating patients with chronic kidney disease (CKD) is designing their diets: an excess of protein leads to the accumulation of uremic toxins, whereas a diet insufficient in protein could lead to loss of lean body mass. The benefits of dietary protein restriction include reducing the accumulation of metabolic waste products that can suppress appetite and stimulate muscle protein wasting. There also is a potential for slowing the loss of kidney function. Unfortunately, advanced CKD is strongly associated with a protein wasting syndrome that is directly correlated with morbidity and mortality. Fortunately, the mechanisms underlying negative responses to an excess of dietary protein, including the causes of the wasting syndrome, are beginning to be understood. We have examined how dietary protein influences the mechanisms causing protein wasting, and we propose a framework for approaching the variable dietary protein requirements in patients with CKD or end-stage kidney disease.