WorldWideScience

Sample records for external driving force

  1. EXTERNAL FORCES DRIVING CHANGE IN THE ROMANIAN SMALL AND MEDIUM SIZED ENTERPRISES

    Directory of Open Access Journals (Sweden)

    Roiban Roxana Nadina

    2012-07-01

    Full Text Available Change is a constant in everyday life confronting organizations to continuously adapt their strategy, structure, processes, and culture in order to survive and stay competitive on the market. Implementing organizational change is one of the most important skills required for managers and in the meantime the most difficult one. The forces driving change within an organization, that can be either external or internal, are those that propel a company forward towards change and in order to identify the need for change and make the proper changes, managers have to develop a tool that allows them to analyze how does the environment influence their business activities. A vision for change will clarify the directions in which the organization needs to move, starting from its current state and taking in consideration the existing opportunities and threats from the environment that allow to move to a future desired state. The purpose of this paper is to identify the concern for change in the Romanian small and medium sized enterprises by presenting and explaining the past and present influences of the main external forces that have determined the need for change in the last 3-5 years and to make recommendations about future possible changes that have to be performed by managers for a better harmonization with the environment. The research method used for this study is the interview on a sample that contains some of the most relevant SME’s from the western side of Romania, from different industries. We analyzed the main external forces that had an impact on the small and medium sized enterprises and how were they generating the need for organizational change, in order to see which present and future changes are required.

  2. Assessment: A Driving Force.

    Science.gov (United States)

    Rakow, Steven J.

    1992-01-01

    Asserts that educational assessment drives the curriculum. Thus, assessment is very important in contemplating reform in science education. Assessment should be an integral part of the instructional process, utilizing diagnostic testing, monitoring, and summative evaluations. (PR)

  3. Technology as a driving force

    Energy Technology Data Exchange (ETDEWEB)

    Torvund, T. [Norsk Hydro A/S (Norway)

    1994-12-31

    The competitiveness of the Norwegian Continental shelf has been put firmly on the agenda in Norway since the report from a working group set up by the Ministry of Industry and Energy was released in February this year. If there is to be secured a long future for oil and gas activities, a reduction in the time and costs used in the projects of the order of 40-50%, without jeopardizing the high safety and environmental standards achieved in Norway. The paper addresses how technology can be a driving force in achieving these aims. But technology alone cannot do the job. Progress and changes in several other areas are also necessary, and the new scenario also calls for improved relations between all actors in the North Sea, authorities, oil companies, contractors and labour unions. 15 figs.

  4. Manipulating single enzymes by an external harmonic force

    DEFF Research Database (Denmark)

    Lomholt, Michael A; Urbakh, Michael; Metzler, Ralf

    2007-01-01

    We study a Michaelis-Menten reaction for a single two-state enzyme molecule, whose transition rates between the two conformations are modulated by an harmonically oscillating external force. In particular, we obtain a range of optimal driving frequencies for changing the conformation of the enzyme...

  5. Chemical driving force for rafting in superalloys

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1997-08-15

    Full Text Available The author provides a brief overview of the chemical driving forces for rafting in superalloys. Until recently, all theories of the driving force for rafting have considered the compositions of the two phases to be fixed, although accepting...

  6. Internal and External Forces in Language Change.

    Science.gov (United States)

    Yang, Charles D.

    2000-01-01

    Develops a model of language change characterizing the dynamic interaction between internal universal grammar and external linguistic evidence, as mediated by language acquisition. Borrows insights from the study of biological evolution, where internal and external forces interact in similar fashion. Applies the model to explore the loss of the…

  7. Synchronization of cardiorhythm by weak external forcing

    Directory of Open Access Journals (Sweden)

    V. S. Anishchenko

    2000-01-01

    Full Text Available We study the possibility to synchronize cardiorhythm of a human by periodic and aperiodic sequences of light and sound pulses. Aperiodic forcing is defined by variation of RR intervals of another subject. Phase locking between cardiorhythm and weak external forcing is detected on finite time intervals. We observe the 1:1 synchronization for periodic forcing and n:m synchronization for aperiodic one.

  8. Forces driving epithelial wound healing

    Science.gov (United States)

    Brugués, Agustí; Anon, Ester; Conte, Vito; Veldhuis, Jim H.; Gupta, Mukund; Colombelli, Julien; Muñoz, José J.; Brodland, G. Wayne; Ladoux, Benoit; Trepat, Xavier

    2014-09-01

    A fundamental feature of multicellular organisms is their ability to self-repair wounds through the movement of epithelial cells into the damaged area. This collective cellular movement is commonly attributed to a combination of cell crawling and `purse-string’ contraction of a supracellular actomyosin ring. Here we show by direct experimental measurement that these two mechanisms are insufficient to explain force patterns observed during wound closure. At early stages of the process, leading actin protrusions generate traction forces that point away from the wound, showing that wound closure is initially driven by cell crawling. At later stages, we observed unanticipated patterns of traction forces pointing towards the wound. Such patterns have strong force components that are both radial and tangential to the wound. We show that these force components arise from tensions transmitted by a heterogeneous actomyosin ring to the underlying substrate through focal adhesions. The structural and mechanical organization reported here provides cells with a mechanism to close the wound by cooperatively compressing the underlying substrate.

  9. Manipulating single enzymes by an external harmonic force

    DEFF Research Database (Denmark)

    Lomholt, Michael A; Urbakh, Michael; Metzler, Ralf

    2007-01-01

    We study a Michaelis-Menten reaction for a single two-state enzyme molecule, whose transition rates between the two conformations are modulated by an harmonically oscillating external force. In particular, we obtain a range of optimal driving frequencies for changing the conformation of the enzyme......, thereby controlling the enzymatic activity (i.e., product formation). This analysis demonstrates that it is, in principle, possible to obtain information about particular rates within the kinetic scheme....

  10. Thermodynamic driving force for rafting in superalloys

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1996-08-01

    Full Text Available Eshelby’s energy-momentum tensor is used to provide an analytical expression for the driving force for rafting in the elastic regime in a super alloy with a high volume fraction of gamma'. The structure is modeled as a simple cubic array of gamma...

  11. Sequential reconstruction of driving-forces from nonlinear nonstationary dynamics

    Science.gov (United States)

    Güntürkün, Ulaş

    2010-07-01

    This paper describes a functional analysis-based method for the estimation of driving-forces from nonlinear dynamic systems. The driving-forces account for the perturbation inputs induced by the external environment or the secular variations in the internal variables of the system. The proposed algorithm is applicable to the problems for which there is too little or no prior knowledge to build a rigorous mathematical model of the unknown dynamics. We derive the estimator conditioned on the differentiability of the unknown system’s mapping, and smoothness of the driving-force. The proposed algorithm is an adaptive sequential realization of the blind prediction error method, where the basic idea is to predict the observables, and retrieve the driving-force from the prediction error. Our realization of this idea is embodied by predicting the observables one-step into the future using a bank of echo state networks (ESN) in an online fashion, and then extracting the raw estimates from the prediction error and smoothing these estimates in two adaptive filtering stages. The adaptive nature of the algorithm enables to retrieve both slowly and rapidly varying driving-forces accurately, which are illustrated by simulations. Logistic and Moran-Ricker maps are studied in controlled experiments, exemplifying chaotic state and stochastic measurement models. The algorithm is also applied to the estimation of a driving-force from another nonlinear dynamic system that is stochastic in both state and measurement equations. The results are judged by the posterior Cramer-Rao lower bounds. The method is finally put into test on a real-world application; extracting sun’s magnetic flux from the sunspot time series.

  12. Ratchet effect on a relativistic particle driven by external forces

    Energy Technology Data Exchange (ETDEWEB)

    Quintero, Niurka R [Departamento de Fisica Aplicada I, Escuela Universitaria Politecnica, Universidad de Sevilla, Calle Virgen de Africa 7, E-41011 Sevilla (Spain); Alvarez-Nodarse, Renato [Departamento de Analisis Matematico, Facultad de Matematicas, Universidad de Sevilla, Apdo 1160, E-41080 Sevilla (Spain); Cuesta, Jose A, E-mail: niurka@us.es, E-mail: ran@us.es, E-mail: cuesta@math.uc3m.es [Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matematicas, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganes, Madrid (Spain)

    2011-10-21

    We study the ratchet effect of a damped relativistic particle driven by both asymmetric temporal bi-harmonic and time-periodic piecewise constant forces. This system can be formally solved for any external force, providing the ratchet velocity as a nonlinear functional of the driving force. This allows us to explicitly illustrate the functional Taylor expansion formalism recently proposed for this kind of systems. The Taylor expansion reveals particularly useful to obtain the shape of the current when the force is periodic, piecewise constant. We also illustrate the somewhat counterintuitive effect that introducing damping may induce a ratchet effect. When the force is symmetric under time-reversal and the system is undamped, under symmetry principles no ratchet effect is possible. In this situation increasing damping generates a ratchet current which, upon increasing the damping coefficient eventually reaches a maximum and decreases toward zero. We argue that this effect is not specific of this example and should appear in any ratchet system with tunable damping driven by a time-reversible external force. (paper)

  13. Three Dimensional Numerical Simulation for the Driving Force of Weld Solidification Cracking

    Institute of Scientific and Technical Information of China (English)

    Zhibo DONG; Yanhong WEI; Renpei LIU; Zujue DONG

    2005-01-01

    The double ellipsoidal model of heat source is used to analyze the thermal distributions with a three dimensional finite element method (FEM). In the mechanical model, solidification effects are treated by a dynamic element rebirth scheme. The driving force is obtained in the cracking susceptible temperature range. Moreover, this paper presents the effect of solidification shrinkage, external restraint, weld start locations and material properties on the driving force. The comparison between the simulated driving force and the experimental measurements of the material resistance predicts the susceptibility of weld metal solidification cracking.

  14. Forces driving epithelial spreading in zebrafish gastrulation.

    Science.gov (United States)

    Behrndt, Martin; Salbreux, Guillaume; Campinho, Pedro; Hauschild, Robert; Oswald, Felix; Roensch, Julia; Grill, Stephan W; Heisenberg, Carl-Philipp

    2012-10-12

    Contractile actomyosin rings drive various fundamental morphogenetic processes ranging from cytokinesis to wound healing. Actomyosin rings are generally thought to function by circumferential contraction. Here, we show that the spreading of the enveloping cell layer (EVL) over the yolk cell during zebrafish gastrulation is driven by a contractile actomyosin ring. In contrast to previous suggestions, we find that this ring functions not only by circumferential contraction but also by a flow-friction mechanism. This generates a pulling force through resistance against retrograde actomyosin flow. EVL spreading proceeds normally in situations where circumferential contraction is unproductive, indicating that the flow-friction mechanism is sufficient. Thus, actomyosin rings can function in epithelial morphogenesis through a combination of cable-constriction and flow-friction mechanisms.

  15. Driving forces in the Greenlandic urbanization

    DEFF Research Database (Denmark)

    Hendriksen, Kåre

    2014-01-01

    Generally urbanization is recognised as a natural development where the population is mowing into the larger towns driven by e.g. better job opportunities, larger product and service supply and better education and health services, and it is often argued that this is also the driving forces...... for accelerating changes in the Greenlandic settlement pattern. Resent research problematize to what extent this logic is so simple? Also in Greenland, with its 56.000 inhabitants spread over 17 so-called towns and 58 settlements, there is a clear correlation between settlement pattern and job opportunities....... This centralization has left geographical regions with limited livelihood and at the same time a lack of utilization of local resources and trade opportunities. Additionally the Greenlandic so called larger cities are ended in an un-sustainable economical situation manly depending on public financed jobs or social...

  16. Current Reversal Due to Coupling Between Asymmetrical Driving Force and Ratchet Potential

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potential are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal. The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals.

  17. Global Plate Driving Forces at 50Ma

    Science.gov (United States)

    Butterworth, N. P.; Quevedo, L. E.; Müller, R. D.

    2011-12-01

    We apply a novel workflow utilising the BEM-Earth geodynamic software to analyse the global coupled plate-mantle dynamics at 50 Ma. A subduction history model based on kinematic data going as far back as 80 Ma was developed using the GPlates software. Advection of the plates into the mantle takes into account the absolute plate motions and lithospheric thickness derived from its age to produce an estimated density heterogeneity initial model condition in the upper mantle. The resulting global model consists of regions of a mantle viscosity and density structure that is post-processed to ensure smooth non-overlapping 3D surfaces. BEM-Earth is then free to evolve the model toward the 50 Ma solution. The evolution of the model is driven by self-consistent buoyancy driven mantle dynamics. We use the model velocity output to quantify changes in forces driving the plates before and after 50 Ma. We analyse the rapid change in plate motion of India, Africa and plates in the Pacific Ocean basin by considering slab-pull, ridge-push and mantle drag/suction forces that naturally result from such top-down driven mantle flow. We compare the results with plate kinematic reconstructions and other geological observations.

  18. Inflammaging: the driving force in osteoporosis?

    Science.gov (United States)

    Lencel, P; Magne, D

    2011-03-01

    With advancing age, the balance between the amounts of old bone removed and new bone formed during the remodelling process becomes negative. In the past, it was commonly thought that skeletal involution was the result of age-related changes in other organs, and in particular from the decline in ovarian function in women at menopause. Nonetheless, with regard to emerging epidemiologic studies, the hypothesis suggesting that age-related changes such as inflammatory modifications importantly account for age-related bone loss is gaining increasing interest. Aging is indeed associated with immune dysfunction that coexists with a chronic subclinical inflammatory status. The latter is illustrated by a 2-4-fold increase in the levels C-reactive protein (CRP) or interleukin (IL)-6. This inflammatory status, which has been referred to by the neologism "inflammaging", is of sufficient magnitude to impact health and survival time, and correlates with age-related diseases such as atherosclerosis, insulin resistance and Alzheimer's disease. In this article, we first present the factors that condition inflammaging, and propose the hypothesis that inflammaging may be the driving force in age-related bone loss and may even be responsible for osteoporosis due to estrogen deficiency. Finally, we discuss the possibility that pro-inflammatory biomarkers may be used to provide clinical information for identifying patients at risk for osteoporosis, and the possibility that inflammatory cytokines may be targeted to improve bone formation in aged patients undergoing orthopaedic surgery.

  19. EXTERNAL BODY FORCE IN FINITE DIFFERENCE LATTICE BOLTZMANN METHOD

    Institute of Scientific and Technical Information of China (English)

    CHEN Sheng; LIU Zhao-hui; SHI Bao-chang; ZHENG Chu-guang

    2005-01-01

    A new finite difference lattice Boltzmann scheme is developed. Because of analyzing the influence of external body force roundly, the correct Navier-Stokes equations with the external body force are recovered, without any additional unphysical terms. And some numerical results are presented. The result which close agreement with analytical data shows the good performance of the model.

  20. Inversion for the driving forces of plate tectonics

    Science.gov (United States)

    Richardson, R. M.

    1983-01-01

    Inverse modeling techniques have been applied to the problem of determining the roles of various forces that may drive and resist plate tectonic motions. Separate linear inverse problems have been solved to find the best fitting pole of rotation for finite element grid point velocities and to find the best combination of force models to fit the observed relative plate velocities for the earth's twelve major plates using the generalized inverse operator. Variance-covariance data on plate motion have also been included. Results emphasize the relative importance of ridge push forces in the driving mechanism. Convergent margin forces are smaller by at least a factor of two, and perhaps by as much as a factor of twenty. Slab pull, apparently, is poorly transmitted to the surface plate as a driving force. Drag forces at the base of the plate are smaller than ridge push forces, although the sign of the force remains in question.

  1. Inversion for the driving forces of plate tectonics

    Science.gov (United States)

    Richardson, R. M.

    1983-01-01

    Inverse modeling techniques have been applied to the problem of determining the roles of various forces that may drive and resist plate tectonic motions. Separate linear inverse problems have been solved to find the best fitting pole of rotation for finite element grid point velocities and to find the best combination of force models to fit the observed relative plate velocities for the earth's twelve major plates using the generalized inverse operator. Variance-covariance data on plate motion have also been included. Results emphasize the relative importance of ridge push forces in the driving mechanism. Convergent margin forces are smaller by at least a factor of two, and perhaps by as much as a factor of twenty. Slab pull, apparently, is poorly transmitted to the surface plate as a driving force. Drag forces at the base of the plate are smaller than ridge push forces, although the sign of the force remains in question.

  2. Rating forces grip and driving and accelerations of the car with drive different configuration

    Directory of Open Access Journals (Sweden)

    Kowalski Mariusz

    2015-12-01

    Full Text Available The paper shows a typical drive systems used in today's vehicles, mainly cars. Approximated scheme of the formation of the driving force of the vehicle and the necessary mathematical relations for the calculation. For example, a typical passenger car BMW 320 was analyzed and calculations obtained a driving force, of adhesion and acceleration. The calculations were performed for the drive system, the classical (i.e. the rear axle of the vehicle for front-wheel drive and four-wheel drive (4×4. Virtually assumed that to the above mentioned vehicle it is possible buildings of each of said system. These are shown graphically in diagrams bearing a distribution of the forces acting on the substrate and the reactions - the data necessary for the calculations. The resulting calculation is graphically shown in the diagrams, in which is illustrated a change value of the resulting adhesive strength, and the acceleration depending on the drive type vehicle.

  3. Shoulder muscle forces during driving: Sudden steering can load the rotator cuff beyond its repair limit.

    Science.gov (United States)

    Pandis, Petros; Prinold, Joe A I; Bull, Anthony M J

    2015-10-01

    Driving is one of the most common everyday tasks and the rotator cuff muscles are the primary shoulder stabilisers. Muscle forces during driving are not currently known, yet knowledge of these would influence important clinical advice such as return to activities after surgery. The aim of this study is to quantify shoulder and rotator cuff muscle forces during driving in different postures. A musculoskeletal modelling approach is taken, using a modified driving simulator in combination with an upper limb musculoskeletal model (UK National Shoulder Model). Motion data and external force vectors were model inputs and upper limb muscle and joint forces were the outputs. Comparisons of the predicted glenohumeral joint forces were compared to in vivo literature values, with good agreement demonstrated (61 SD 8% body weight mean peak compared to 60 SD 1% body weight mean peak). High muscle activation was predicted in the rotator cuff muscles; particularly supraspinatus (mean 55% of the maximum and up to 164 SD 27 N). This level of loading is up to 72% of mean failure strength for supraspinatus repairs, and could therefore be dangerous for some cases. Statistically significant and large differences are shown to exist in the joint and muscle forces for different driving positions as well as steering with one or both hands (up to 46% body weight glenohumeral joint force). These conclusions should be a key consideration in rehabilitating the shoulder after surgery, preventing specific upper limb injuries and predicting return to driving recommendations. Copyright © 2015. Published by Elsevier Ltd.

  4. Equatorial Rossby Solitary Wave Under the External Forcing

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Kuo; LIU Shi-Da

    2005-01-01

    A simple shallow-water model with influence of external forcing on a β-plane is applied to investigate the nonlinear equatorial Rossby waves in a shear flow. By the perturbation method, the extended variable-coefficient KdV equation under an external forcing is derived for large amplitude equatorial Rossby wave in a shear flow. And then various periodic-like structures for these equatorial Rossby waves are obtained with the help of Jacobi elliptic functions.It is shown that the external forcing plays an important role in various periodic-like structures.

  5. OSHA Laboratory Standard: Driving Force for Laboratory Safety!

    Science.gov (United States)

    Roy, Kenneth R.

    2000-01-01

    Discusses the Occupational Safety and Health Administration's (OSHA's) Laboratory Safety Standards as the major driving force in establishing and maintaining a safe working environment for teachers and students. (Author)

  6. Driving Force Filtering and Driving Mechanism Analysis of Urban Agricultural Development in Weifang County, China

    Directory of Open Access Journals (Sweden)

    SUI Fei-fei

    2016-03-01

    Full Text Available As an agricultural nation, the agricultural landscape is the basic appearance and existence in China, but the common existence often be neglected and contempted. As a new type of design and ideology, the development of urban agricultural landscape will greatly affect the texture and structure of the urban space. According to the urban agricultural production data and the socio-economic data of Weifang County, a set of evaluation index system that could analyze quantitatively the driving force of urban agricultural production changes and the internal drive mechanism was built. The original driving force indicators of economy, society, resources and environment from the time-series were chosen, and then 15 driving forces from the original driving forces by correlation analysis and principal component analysis were selected. The degree of influence was analyzed and the driving forces model by means of partial least squares(PLS was built. The results demonstrated that the factors greatly influenced the increase of urban agricultural output value in Weifang County were per capita net income of rural residents, agricultural machinery total power, effective irrigation area, centralized treatment rate of urban sewage, with the driving exponents 0.2509, 0.1019, 0.1655, 0.1332, respectively. The negative influence factor was the use amount of agricultural plastic film and the driving exponent was-0.2146. The research provides a reference for the development of urban agriculture, as well as a reference for the related study.

  7. Response of Brownian Fluctuations to External Forces

    Science.gov (United States)

    Laub, Jeffrey William

    Millikan's law of particle fall is an empirical result which shows the dependence of particle fall rate in a gas on particle radius and host gas density. The size of submicron particles in gases has long been determined by Millikan's law. The dominant factor is Stokes' law with a correction added to account for the physics of slip. However, it was recently shown by Kim and Fedele that Brownian fluctuations affect the fall rate while showing no anomalies in the density dependence of the rms displacement. The effect was an enhancement of the fall rate of small particles as the density of the host gas is increased. This enhancement showed a size dependence in the form of a smooth transition from the one of decreasing fall rate with increasing density for large particles (~0.4 μm radius) to another of increasing fall rate with increasing gas density for small particles ( ~0.15mum radius). The magnitude of the anomaly is determined by how the rms Brownian velocity compares with its fall rate. In an effort to understand the effect of Brownian fluctuations coupling with gravity, a new experiment has been carried out where an AC field was applied to force particles to fluctuate more in the vertical direction on one hand and where a constant DC field was applied to change the effective force of gravity on the other. These fields were applied to a charged oil drop in the 0.2 to 0.3 μm radius range falling in a nitrogen environment. Displacements over a 4 second time interval were repeatedly measured in both the vertical and horizontal directions. The original experimental apparatus was used with some modifications. The modifications included computer automation of particle control and data taking to allow for longer use of the same particle, up to 120 hours, and to facilitate application of the additional fields. The objective was to make large particles appear to be smaller via forced oscillations and make them fall faster or slower via the DC bias to effect the change in

  8. EEO External Relevant Labor Force Analysis

    Science.gov (United States)

    1980-09-01

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  9. The Driving Forces of Subsidiary Absorptive Capacity

    DEFF Research Database (Denmark)

    Schleimer, Stephanie C.; Pedersen, Torben

    2013-01-01

    The study investigates how a multinational corporation (MNC) can promote the absorptive capacity of its subsidiaries. The focus is on what drives the MNC subsidiary's ability to absorb marketing strategies that are initiated by the MNC parent, as well as how the subsidiary enacts on this absorptive...... as a purposeful response to this dual embeddedness. An analysis of marketing strategy absorptions undertaken by 213 subsidiaries reveals that MNCs can assist their subsidiaries to compete in competitive and dynamic focal markets by forming specific organizational mechanisms that are conducive to the development...

  10. How do cells produce and regulate the driving force in the process of migration?

    Science.gov (United States)

    Zhong, Y.; Ji, B.

    2014-06-01

    Cell migration behaviors have been studied from various aspects and at different length scales (molecular, subcellular and cellular scales), however, the mechanisms of how cell produces and controls the driving force for its migration have not been fully understood. Here for the first time we draw a more unified picture of driving force production that integrates the mechanisms from molecular to subcellular and cellular levels to show how cell produces and regulates the driving force and thus control its motility. We suggest that although the external mechanical and chemical factors can influence cell migration, the cell is able to actively control and regulate its driving force for its motility through controlling the stability of cell adhesion via actively regulating its spreading shape. To demonstrate this picture of regulation of the driving force, a FEM-based simulation framework is developed by modeling the dynamics of adhesion at cell front, de-adhesion at cell rear, and forward motion of cell body under cell traction force for different cell shape. The migration of keratocyte and fibroblast cells is simulated for different matrix rigidity and rigidity gradient. We show that the cell migration speed biphasically depends on the matrix rigidity. The mechanism is that the variation of matrix rigidity tunes the balance of competition between stability of cell adhesion at cell front and instability of adhesion at cell rear, which consequently controls the driving force of cell migration. We further propose a parameter called motility factor for a quantitative description of impact of mechanical properties of matrix and cell shape on the driving force of cell migration.

  11. Contributions of Determining the Forces Distribution in the Harmonic Drive

    Directory of Open Access Journals (Sweden)

    Sava Ianici

    2006-10-01

    Full Text Available The paper presents an original method for determining the forces distributions on the portant elements of the harmonic drives. This method is based on the thin wall shells theory anal on the rotating character of the distributed forces that work upon the flexible toothed wheel.

  12. Stability of GOY Model Under Modulation of Periodic External Force

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ying-Kui; CHEN Shi-Gang; WANG Guang-Rui

    2008-01-01

    There is a phase transition between quasi-periodic state and intermittent chaos in GOY model with a critical value δ0. When we add a modulated periodic external force to the system, the phase transition can also be found with a critical value δe. Due to coupling between the force and the intrinsic fluctuation of the velocity on shells in GOY model, the stability of the system has been changed, which results in the variation of the critical value. For proper intensity and period of the force, δe is unequal to δ0. The critical value is a nonlinear function of amplitude of the force, and the fluctuation of the velocity can resonate with the external force for certain period Te.

  13. Analyzing the Long Term Cohesive Effect of Sector Specific Driving Forces.

    Science.gov (United States)

    Berman, Yonatan; Ben-Jacob, Eshel; Zhang, Xin; Shapira, Yoash

    2016-01-01

    Financial markets are partially composed of sectors dominated by external driving forces, such as commodity prices, infrastructure and other indices. We characterize the statistical properties of such sectors and present a novel model for the coupling of the stock prices and their dominating driving forces, inspired by mean reverting stochastic processes. Using the model we were able to explain the market sectors' long term behavior and estimate the coupling strength between stocks in financial markets and the sector specific driving forces. Notably, the analysis was successfully applied to the shipping market, in which the Baltic dry index (BDI), an assessment of the price of transporting the major raw materials by sea, influences the shipping financial market. We also present the analysis of other sectors-the gold mining market and the food production market, for which the model was also successfully applied. The model can serve as a general tool for characterizing the coupling between external forces and affected financial variables and therefore for estimating the risk in sectors and their vulnerability to external stress.

  14. Analyzing the Long Term Cohesive Effect of Sector Specific Driving Forces.

    Directory of Open Access Journals (Sweden)

    Yonatan Berman

    Full Text Available Financial markets are partially composed of sectors dominated by external driving forces, such as commodity prices, infrastructure and other indices. We characterize the statistical properties of such sectors and present a novel model for the coupling of the stock prices and their dominating driving forces, inspired by mean reverting stochastic processes. Using the model we were able to explain the market sectors' long term behavior and estimate the coupling strength between stocks in financial markets and the sector specific driving forces. Notably, the analysis was successfully applied to the shipping market, in which the Baltic dry index (BDI, an assessment of the price of transporting the major raw materials by sea, influences the shipping financial market. We also present the analysis of other sectors-the gold mining market and the food production market, for which the model was also successfully applied. The model can serve as a general tool for characterizing the coupling between external forces and affected financial variables and therefore for estimating the risk in sectors and their vulnerability to external stress.

  15. Motive, desire, drive: the discourse of force

    Directory of Open Access Journals (Sweden)

    Alan Blum

    2013-12-01

    Full Text Available A review of the original paper on motive by Blum and McHugh (1971 is used as an occasion to make transparent an approach to social theory as it has developed over the years in their work. This method, in treating motive as an illustration, engages it as an example of the status of the signifier as a symptom of interpretive conflict endemic to any situation of action, always inviting an analysis of the symbolic order and imaginative structure that sustains the distinction as a force in social life. In this paper, motive in particular is unpacked to show how it serves as an indication of fundamental ambiguity with respect to a problem-solving situation, revealing in this case constant perplexity in relation to the enigmatic character of what comes to view on any occasion and the recurrent contestation that is released.

  16. Ocean forcing drives glacier retreat sometimes

    Science.gov (United States)

    Bassis, J. N.; Ultee, E.; Ma, Y.

    2015-12-01

    Observations show that marine-terminating glaciers respond to climate forcing nonlinearly, with periods of slow or negligible glacier advance punctuated by abrupt, rapid retreat. Once glacier retreat has initiated, glaciers can quickly stabilize with a new terminus position. Alternatively, retreat can be sustained for decades (or longer), as is the case for Columbia Glacier, Alaska where retreat initiated ~1984 and continues to this day. Surprisingly, patterns of glacier retreat show ambiguous or even contradictory correlations with atmospheric temperature and glacier surface mass balance. Despite these puzzles, observations increasingly show that intrusion of warm subsurface ocean water into fjords can lead to glacier erosion rates that can account for a substantial portion of the total mass lost from glaciers. Here we use a simplified flowline model to show that even relatively modest submarine melt rates (~100 m/a) near the terminus of grounded glaciers can trigger large increases in iceberg calving leading to rapid glacier retreat. However, the strength of the coupling between submarine melt and calving is a strong function of the geometry of the glacier (bed topography, ice thickness and glacier width). This can lead to irreversible retreat when the terminus is thick and grounded deeply beneath sea level or result in little change when the glacier is relatively thin, grounded in shallow water or pinned in a narrow fjord. Because of the strong dependence on glacier geometry, small perturbations in submarine melting can trigger glaciers in their most advanced—and geometrically precarious—state to undergo sudden retreat followed by much slower re-advance. Although many details remain speculative, our model hints that some glaciers are more sensitive than others to ocean forcing and that some of the nonlinearities of glacier response to climate change may be attributable to variations in difficult-to-detect subsurface water temperatures that need to be better

  17. Materials Bound by Non-Chemical Forces: External Fields and the Quantum Vacuum

    CERN Document Server

    Swain, John; Srivastava, Yogendra

    2014-01-01

    We discuss materials which owe their stability to external fields. These include: 1) external electric or magnetic fields, and 2) quantum vacuum fluctuations in these fields induced by suitable boundary conditions (the Casimir effect). Instances of the first case include the floating water bridge and ferrofluids in magnetic fields. An example of the second case is taken from biology where the Casimir effect provides an explanation of the formation of stacked aggregations or "rouleaux" by negatively charged red blood cells. We show how the interplay between electrical and Casimir forces can be used to drive self-assembly of nano-structured materials, and could be generalized both as a probe of Casimir forces and as a means of manufacturing nanoscale structures. Interestingly, all the cases discussed involve the generation of the somewhat exotic negative pressures. We note that very little is known about the phase diagrams of most materials in the presence of external fields other than those represented by the ...

  18. failure analysis and shock protection of external hard disk drive

    African Journals Online (AJOL)

    user

    Technology for processing and storage of data in portable external storage hard disks has ... system was used to simulate the impact of stress on the structure of the hard disk before and ... highlighted [1] that mechanical vibration and shock.

  19. On Optimizing Steering Performance of Multi-axle Vehicle Based on Driving Force Control

    Directory of Open Access Journals (Sweden)

    Wu Zhicheng

    2017-01-01

    Full Text Available The steering performance of multi-axle vehicle with independent driving system is affected by the distribution of the wheel driving force. A nonlinear vehicle dynamics model including magic formula tire model for describing 11 DoF four-axle vehicle with dual-front-axle-steering (DFAS system was presented. The influence of different driving force distribution scheme on the steering performance of the vehicle was analyzed. A control strategy for improving the steady response and transient response of the vehicle steering is proposed. The results show: For the steady response, setting different drive force for internal and external wheels according to the actual steering characteristics of the vehicle can effectively improve its steering characteristics; For the transient response, adopting the zero sideslip angle control strategy and using the PID control algorithm to control the driving force of the outside wheel of tear-two-axle, under angle step input, the vehicle sideslip angle can quickly stabilize to 0 and yaw rate also significantly decreases.

  20. External Force Estimation for Teleoperation Based on Proprioceptive Sensors

    Directory of Open Access Journals (Sweden)

    Enrique del Sol

    2014-03-01

    Full Text Available This paper establishes an approach to external force estimation for telerobotic control in radioactive environments by the use of an identified manipulator model and pressure sensors, without employing a force/torque sensor. The advantages of - and need for - force feedback have been well-established in the field of telerobotics, where electrical and back-drivable manipulators have traditionally been used. This research proposes a methodology employing hydraulic robots for telerobotics tasks based on a model identification scheme. Comparative results of a force sensor and the proposed approach using a hydraulic telemanipulator are presented under different conditions. This approach not only presents a cost effective solution but also a methodology for force estimation in radioactive environments, where the dose rates limit the use of electronic devices such as sensing equipment.

  1. Power, muscular work, and external forces in cycling.

    Science.gov (United States)

    de Groot, G; Welbergen, E; Clijsen, L; Clarijs, J; Cabri, J; Antonis, J

    1994-01-01

    Cycling performance is affected by the interaction of a number of variables, including environment, mechanical, and human factors. Engineers have focused on the development of more efficient bicycles. Kinesiologists have examined cycling performance from a human perspective. This paper summarizes only certain aspects of human ergonomics of cycling, especially those which are important for the recent current research in our departments. Power is a key to performance of physical work. During locomotion an imaginary flow of energy takes place from the metabolism to the environment, with some efficiency. The 'useful' mechanical muscle power output might be used to perform movements and to do work against the environment. The external power is defined as the sum of joint powers, each calculated as the product of the joint (net) moment and angular velocity. This definition of external power is closely related to the mean external power as applied to exercise physiology: the sum of joint powers reflects all mechanical power which in principle can be used to fulfil a certain task. In this paper, the flow of energy for cycling is traced quantitatively as far as possible. Studies on the total lower limb can give insight into the contribution of individual muscles to external power. The muscle velocity (positive or negative) is obtained from the positions and orientations of body segments and a bar linkage model of the lower limb. The muscle activity can be measured by electromyography. In this way, positive and negative work regions in individual muscles are identified. Synergy between active agonistic/antagonistic muscle groups occurs in order to deliver external power. Maximum power is influenced by body position, geometry of the bicycle and pedalling rate. This has to be interpreted in terms of the length-tension and force-velocity-power relationships of the involved muscles. Flat road and uphill cycling at different saddle-tube angles is simulated on an ergometer. The

  2. Measuring Industry Coagglomeration and Identifying the Driving Forces

    DEFF Research Database (Denmark)

    Howard, Emma; Newman, Carol; Tarp, Finn

    2015-01-01

    Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We construct a new coagglomeration index based purely on the location of firms. We ...

  3. WP/084 Measuring Industry Agglomeration and Identifying the Driving Forces

    DEFF Research Database (Denmark)

    Howard, Emma; Tarp, Finn; Newman, Carol

    Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We propose a new measure and examine what it reveals about the importance of transp...

  4. Atlantic Meridional Overturning Circulation response to idealized external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Park, W.; Latif, M. [Leibniz-Institut fuer Meereswissenschaften an der Universitaet Kiel, Kiel (Germany)

    2012-10-15

    The response of the Atlantic Meridional Overturning Circulation (AMOC) to idealized external (solar) forcing is studied in terms of the internal (unforced) AMOC modes with the Kiel Climate Model (KCM), a coupled atmosphere-ocean-sea ice general circulation model. The statistical investigation of KCM's internal AMOC variability obtained from a multi-millennial control run yields three distinct modes: a multi-decadal mode with a period of about 60 years, a quasi-centennial mode with a period of about 100 years and a multi-centennial mode with a period of about 300-400 years. Most variance is explained by the multi-centennial mode, and the least by the quasi-centennial mode. The solar constant varies sinusoidally with two different periods (100 and 60 years) in forced runs with KCM. The AMOC response to the external forcing is rather complex and nonlinear. It involves strong changes in the frequency structure of the variability. While the control run depicts multi-timescale behavior, the AMOC variability in the experiment with 100 year forcing period is channeled into a relatively narrow band centered near the forcing period. It is the quasi-centennial AMOC mode with a period of just under 100 years which is excited, although it is heavily damped in the control run. Thus, the quasi-centennial mode retains its period which does not correspond exactly to the forcing period. Surprisingly, the quasi-centennial mode is also most strongly excited when the forcing period is set to 60 years, the period of the multi-decadal mode which is rather prominent in the control run. It is largely the spatial structure of the forcing rather than its period that determines which of the three internal AMOC modes is excited. The results suggest that we need to understand the full modal structure of the internal AMOC variability in order to understand the circulation's response to external forcing. This could be a challenge for climate models: we cannot necessarily expect that the

  5. External Costs as Driving Forces of Land Use Changes

    Directory of Open Access Journals (Sweden)

    Dirk Loehr

    2010-04-01

    Full Text Available Land conversion is often not carried out in a sustainable way. The loss of arable land and biodiversity, concern about food security and rising costs of infrastructure due to urban sprawl are just some of the problems under discussion. This paper compares Germany, China and Cambodia. The article points out that, despite huge differences in institutions and governance, unsustainable land use changes mostly have some patterns in common: The beneficiaries of land conversion are often well-organized actors, whereas the costs of land conversion are often shifted to poorly organized groups and to society as a whole. A sustainable land use policy has to look for a better coupling of benefits and costs of land use changes. In order to achieve this goal, the article suggests completing the planning law with a suitable economic framework.

  6. WP/084 Measuring Industry Agglomeration and Identifying the Driving Forces

    DEFF Research Database (Denmark)

    Howard, Emma; Tarp, Finn; Newman, Carol

    Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We propose a new measure and examine what it reveals about the importance of transp......Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We propose a new measure and examine what it reveals about the importance...... of transport costs, labour market pooling, and technology transfer for agglomeration processes. We contrast this analysis with insights from existing measures in the literature and find very different underlying stories at work. An exceptionally rich set of data from Vietnam makes us confident that our measure...

  7. Improved Generalized Force Model considering the Comfortable Driving Behavior

    Directory of Open Access Journals (Sweden)

    De-Jie Xu

    2015-01-01

    Full Text Available This paper presents an improved generalized force model (IGFM that considers the driver’s comfortable driving behavior. Through theoretical analysis, we propose the calculation methods of comfortable driving distance and velocity. Then the stability condition of the model is obtained by the linear stability analysis. The problems of the unrealistic acceleration of the leading car existing in the previous models were solved. Furthermore, the simulation results show that IGFM can predict correct delay time of car motion and kinematic wave speed at jam density, and it can exactly describe the driver’s behavior under an urgent case, where no collision occurs. The dynamic properties of IGFM also indicate that stability has improved compared to the generalized force model.

  8. DYNAMICS OF SANDY DESERTIFICATION AND ITS DRIVING FORCES IN WESTERN JILIN PROVINCE

    Institute of Scientific and Technical Information of China (English)

    LI Fang; HE Yan-fen; LIU Zhi-ming; ZHANG Bai

    2004-01-01

    By establishing the interpreting elements, and applying supervised classification, the sandy desertification was interpreted and the desertified land areas of the counties in the western Jilin Province in 1986 and in 2000 were obtained. Taking Tongyu and Qian'an as examples, the natural driving forces and man-made driving forces were analyzed. The paper comes the conclusions that the material sources and the warming and dry climate are the internal causes of potential land desertification; the irrational human activities, such as destroying forest and reclaiming the grassland, are the external causes of potential land desertification; while more rational human activities, such as planting trees and restoring grassland can reverse the land desertification. Furthermore, the countermeasures and suggestions for the development of agriculture and animal husbandry in the western Jilin Province are put forward.

  9. Quantum Statistics of a Forced Oscillator with a Time-Dependent Driving Force

    Institute of Scientific and Technical Information of China (English)

    刘文森

    2003-01-01

    Quantum statistics of a forced harmonic oscillator acted upon by a time-dependent external force are derived using the Wilcox trick and the time-dependent inhomogeneous Bogoliubov transformation formalism.The internal energy,fluctuation of the particle-number average and entropy of this nonequilibrium system are presented explicitly.

  10. External driving synchronization in a superconducting quantum interference device based oscillator

    Science.gov (United States)

    Zhao, Jie; Zhao, Peng; Yu, Haifeng; Yu, Yang

    2016-11-01

    We propose an external driving, self-sustained oscillator based on superconducting resonators. The dynamics of the self-sustained oscillator can be described by a Duffing-van der Pol like equation. Under external driving, the self-sustained oscillator presents synchronization phenomena. We analytically and numerically investigate the synchronization regions, and the results show that the synchronization bandwidth can be quickly adjusted in situ by the external weak magnetic field in sub-nano seconds. Moreover, the system can re-stabilize in about 10 ns with a certain sudden change of driving frequency or the critical current of the superconducting quantum interference device (SQUID). These advantages allow the potential applications of self-sustained oscillators in timing reference, microwave communication and electromagnetic sensing.

  11. Impact of External Cue Validity on Driving Performance in Parkinson's Disease

    Directory of Open Access Journals (Sweden)

    Karen Scally

    2011-01-01

    Full Text Available This study sought to investigate the impact of external cue validity on simulated driving performance in 19 Parkinson's disease (PD patients and 19 healthy age-matched controls. Braking points and distance between deceleration point and braking point were analysed for red traffic signals preceded either by Valid Cues (correctly predicting signal, Invalid Cues (incorrectly predicting signal, and No Cues. Results showed that PD drivers braked significantly later and travelled significantly further between deceleration and braking points compared with controls for Invalid and No-Cue conditions. No significant group differences were observed for driving performance in response to Valid Cues. The benefit of Valid Cues relative to Invalid Cues and No Cues was significantly greater for PD drivers compared with controls. Trail Making Test (B-A scores correlated with driving performance for PDs only. These results highlight the importance of external cues and higher cognitive functioning for driving performance in mild to moderate PD.

  12. Numerical studies of a plasma diode with external forcing

    Science.gov (United States)

    Rekaa, V. L.; Pécseli, H. L.; Trulsen, J. K.

    2012-08-01

    With reference to laboratory Q-machine studies we analyze the dynamics of a plasma diode under external forcing. Assuming a strong axial magnetic field, the problem is analyzed in one spatial dimension by a particle-in-cell code. The cathode is assumed to be operated in electron rich conditions, supplying an abundance of electrons. We compare different forcing schemes with the results obtained by solving the van der Pol equation. In one method of forcing we apply an oscillation in addition to the DC end plate bias and consider both amplitude and frequency variations. An alternative method of perturbation consists of modelling an absorbing grid at some internal position. Also in this case we can have a constant frequency with varying amplitude or alternatively an oscillation with chirped frequency but constant amplitude. We find that the overall features of the forced van der Pol equation are recovered, but the details in the plasma response need more attention to the harmonic responses, requiring extensions of the model equation. The analysis is extended by introducing collisional effects, where we emphasize charge exchange collisions of ions, since these processes usually have the largest cross sections and give significant modifications of the diode performance. In particular we find a reduction in oscillator frequency, although a linear scaling of the oscillation time with the system length remains also in this case.

  13. Impact assessment of land use planning driving forces on environment

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Longgao, E-mail: chenlonggao@163.com [Institute of Land Resources, Jiangsu Normal University (JSNU), Xuzhou 221116 (China); Yang, Xiaoyan [Institute of Land Resources, Jiangsu Normal University (JSNU), Xuzhou 221116 (China); School of Environment and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116 (China); Chen, Longqian [School of Environment and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116 (China); Li, Long [Department of Geography, Vrije Universiteit Brussel, Brussels 1050 (Belgium)

    2015-11-15

    Land use change may exert a negative impact on environmental quality. A state–impact–state (SIS) model describing a state transform under certain impacts has been integrated into land use planning (LUP) environmental impact assessment (LUPEA). This logical model is intuitive and easy to understand, but the exploration of impact is essential to establish the indicator system and to identify the scope of land use environmental impact when it is applied to a specific region. In this study, we investigated environmental driving forces from land use planning (LUPF), along with the conception, components, scope, and impact of LUPF. This method was illustrated by a case study in Zoucheng, China. Through the results, we concluded that (1) the LUPF on environment are impacts originated from the implementation of LUP on a regional environment, which are characterized by four aspects: magnitude, direction, action point, and its owner; (2) various scopes of LUPF on individual environmental elements based on different standards jointly define the final scope of LUPEA; (3) our case study in Zoucheng demonstrates the practicability of this proposed approach; (4) this method can be embedded into LUPEA with direction, magnitudes, and scopes of the LUPF on individual elements obtained, and the identified indicator system can be directly employed into LUPEA and (5) the assessment helps to identify key indicators and to set up a corresponding strategy to mitigate the negative impact of LUP on the environment, which are two important objectives of strategic environmental assessment (SEA) in LUP. - Highlights: • Environmental driving forces from land use planning (LUPF) are investigated and categorized. • Our method can obtains the direction, magnitudes and scopes of environmental driving forces. • The LUPEA scope is determined by the combination of various scopes of LUPF on individual elements. • LUPF assessment can be embedded into LUPEA. • The method can help to

  14. Imprint of external climate forcing on coastal upwelling in past and future climate

    Directory of Open Access Journals (Sweden)

    N. Tim

    2015-11-01

    Full Text Available The Eastern Boundary Upwelling Systems are the major coastal upwelling regions. The trade winds are driving these upwelling regimes located in the subtropics at the eastern boundary of the Atlantic and Pacific Ocean. Here we analyse the impact of the external climate forcing, e.g. the greenhouse gas concentration, solar activity and volcano eruptions, on these upwelling systems in simulations of ensembles of two Earth System Models. The ensembles contain three simulations for each time period which cover the past millennium (900–1850, the 20th century (1850–2005 and the near future (2006–2100. Using a set of simulations, differing only in their initial conditions, enables us to detect whether the variability is driven internally or externally. Our analysis shows that the variability of the simulated upwelling is to the most driven internally and that there are no significant trends except for the scenario with the most dramatic increase of greenhouse gas concentrations.

  15. Analysis of two phase mass transfer kinetics by logarithmic driving force based on chemical thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Nabeshima, Masahiro (Sumitomo Metal Mining Co. Ltd., Tokai, Ibaraki (Japan). Tokai Research Center)

    1994-09-01

    Interphase transfer kinetics of neodymium and nitric acid was studied using a single drop column with recycling organic phase via an external mixing vessel in H[sub 2]O-HNO[sub 3]/NaNO[sub 3]-Nd(NO[sub 3])[sub 3]-tri-n-butylphosphate system. Experimental data have been analyzed by two new concepts for driving forces for transport: synthesized linear and logarithmic forms. The former is defined as geometrical-mean driving force, and the latter is the logarithm of the product of reciprocals of concentration ratios x/x[sup e] and y/y[sup e] against equilibrium states in each phase, i.e. ln[l brace]x[sup e][center dot]y([sup e])/(x[center dot]y)[r brace]. By applying thermodynamic logarithmic form of driving force along reaction coordinate, the net transfer fluxes of neodymium and nitric acid have been represented by chemical affinity under high ionic strengths over a wide range of solvent loading as flux=flux deg[sub f](1-exp(-A/RT)). (author).

  16. Temperature response to external forcing in simulations and reconstructions of the last millennium

    Directory of Open Access Journals (Sweden)

    L. Fernández-Donado

    2012-08-01

    Full Text Available The understanding of natural climate variability and its driving factors is crucial to assess future climate change. Therefore, comparing proxy-based climate reconstructions with forcing factors as well as comparing these with paleoclimate model simulations is key to gain insights into the relative roles of internal versus forced variability. A review of the state of modeling of the last millennium climate previous to the CMIP5-PMIP3 coordinated effort is presented and compared to the available temperature reconstructions. Simulations and reconstructions broadly agree on reproducing the major temperature changes and suggest an overall linear response to external forcing on multidecadal or longer timescales. Internal variability is found to have an important influence at hemispheric and global scales. The spatial distribution of simulated temperature changes during the transition of the Medieval Climate Anomaly to the Little Ice Age disagrees with that found in the reconstructions, thus advocating for internal variability as a possible major player in shaping temperature changes through the millennium.

    A paleo transient climate response (PTCR is defined to provide a quantitative framework for analysing the consistency between simulated and reconstructed climate. Beyond an overall agreement between simulated and reconstructed PTCR ranges, this analysis is able to single out specific discrepancies between some reconstructions and the ensemble of simulations. The disagreement is found in the cases where the reconstructions show reduced covariability with external forcings or when they present high rates of temperature change.

  17. Solvent effects and driving forces in pillararene inclusion complexes.

    Science.gov (United States)

    Schönbeck, Christian; Li, Hui; Han, Bao-Hang; Laursen, Bo W

    2015-06-04

    Pillararenes, a recently discovered class of aromatic macrocycles, form inclusion complexes with a large number of guest molecules, but not much is known about the driving forces of complexation, including the role of the solvent. We have measured the binding thermodynamics for a small number of model complexes in several solvents and used computational chemistry to rationalize the obtained results and identify the driving forces of complexation. Favorable electrostatic interactions between the host and guest are obtained when the charge distribution in the guest matches the negative electrostatic potential in the cavity of the pillararene. Polar guests, however, also interact strongly with polar solvents, thereby shifting the complexation equilibrium away from the complex. The shape of the solvent molecules is another important factor as some solvents are sterically hindered from entering the pillararene cavity. By changing solvent from acetonitrile to o-xylene the binding constant in one case increased more than 4 orders of magnitude. Even electrostatically similar solvents such as o-xylene and p-xylene have very different impacts on the binding constants due to their different abilities to fit into the cavity. The study illustrates the importance of taking into account the interactions between the solvent and the complexing species in the investigation and design of molecular host:guest systems.

  18. Interaction forces drive the environmental transmission of pathogenic protozoa.

    Science.gov (United States)

    Dumètre, Aurélien; Aubert, Dominique; Puech, Pierre-Henri; Hohweyer, Jeanne; Azas, Nadine; Villena, Isabelle

    2012-02-01

    The protozoan parasites Giardia duodenalis, Cryptosporidium spp., and Toxoplasma gondii are pathogens that are resistant to a number of environmental factors and pose significant risks to public health worldwide. Their environmental transmission is closely governed by the physicochemical properties of their cysts (Giardia) and oocysts (Cryptosporidium and Toxoplasma), allowing their transport, retention, and survival for months in water, soil, vegetables, and mollusks, which are the main reservoirs for human infection. Importantly, the cyst/oocyst wall plays a key role in that regard by exhibiting a complex polymeric coverage that determines the charge and hydrophobic characteristics of parasites' surfaces. Interaction forces between parasites and other environmental particles may be, in a first approximation, evaluated following the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. However, due to the molecular topography and nano- to microstructure of the cyst/oocyst surface, non-DVLO hydrophobic forces together with additional steric attractive and/or repulsive forces may play a pivotal role in controlling the parasite behavior when the organism is subjected to various external conditions. Here, we review several parameters that enhance or hinder the adhesion of parasites to other particles and surfaces and address the role of fast-emerging techniques for mapping the cyst/oocyst surface, e.g., by measuring its topology and the generated interaction forces at the nano- to microscale. We discuss why characterizing these interactions could be a crucial step for managing the environmental matrices at risk of microbial pollution.

  19. Entropic stochastic resonance without external force in oscillatory confined space

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Department of Chemical Physics and Hefei National Laboratory for Physical Sciences at Microscales, iChEM, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-05-21

    We have studied the dynamics of Brownian particles in a confined geometry of dumbbell-shape with periodically oscillating walls. Entropic stochastic resonance (ESR) behavior, characterizing by a maximum value of the coherent factor Q at some optimal level of noise, is observed even without external periodic force in the horizontal direction, which is necessary for conventional ESR where the wall is static and the particle is subjected to the force. Interestingly, the ESR can be remarkably enhanced by the particle gravity G, in contrast to the conventional case. In addition, Q decreases (increases) with G in the small (large) noise limit, respectively, while it non-monotonically changes with G for moderate noise levels. We have applied an effective 1D coarsening description to illustrate such a nontrivial dependence on G, by investigating the property of the 1D effective potential of entropic nature and paying special attention to the excess part resulting from the boundary oscillation. Dependences of the ESR strength with other related parameters are also discussed.

  20. The Dynamics and Driving Force of Farmland Ecosystem Productivity

    Institute of Scientific and Technical Information of China (English)

    ZHONG Liang-ping; SHAO Ming-an; LI Yu-shan

    2005-01-01

    Based on the experimental data of crop yield, soil water and fertility of a dryland farming ecosystem in northwest China, a systematic analysis is carried out to study the dynamics of dryland farming ecosystem productivity and its limiting factors. This paper also discusses which of the two limiting factors, i.e., soil water or fertility, is the primary factor and their dynamics. The result shows that fertility is the primary limiting factor when the productivity is rather low. As chemical fertilizer input increases and the productivity promotes, water gradually becomes the primary limiting factor. Chemical fertilizers and plastic film mulching are the two major driving forces that determine the crop productivity and its stability in these areas.

  1. The driving forces of landscape change in Europe

    DEFF Research Database (Denmark)

    Plieninger, Tobias; Draux, Hélène; Fagerholm, Nora

    2016-01-01

    underrepresented landscapes; (b) clarifying the identification and role of actors in landscape change; (c) deploying more robust tools and methods to quantitatively assess the causalities of landscape change; (d) setting up long-term studies that go beyond mapping land-cover change only; (e) strengthening cross......Over the past decades, landscapes worldwide have experienced changes (e.g., urbanization, agricultural intensification, expansion of renewable energy uses) at magnitudes that put their sustainability at risk. The understanding of the drivers of these landscape changes remains challenging, partly...... because landscape research is spread across many domains and disciplines. We here provide a systematic synthesis of 144 studies that identify the proximate and underlying drivers of landscape change across Europe. First, we categorize how driving forces have been addressed and find that most studies...

  2. Multiple Forces Driving China's Economic Development: A New Analytic Framework

    Institute of Scientific and Technical Information of China (English)

    Yahua Wang; Angang Hu

    2007-01-01

    Based on economic growth theory and the World Bank's analytical framework relating to the quality of growth, the present paper constructs a framework that encompasses physical, international, human, natural and knowledge capital to synthetically interpret economic development. After defining the five types of capital and total capital, we analyze the dynamic changes of these types of capital in China and in other countries. The results show that since China's reform and opening up, knowledge, international, human and physical capital have grown rapidly, with speeds of growth higher than that of economic growth. As the five types of capital have all increased at varying paces, the savings level of total capital in China has quadrupled in 25 years and overtook that of the USA in the 1990s. The changes in the five types of capital and total capital reveal that there are progressively multiple driving forces behind China's rapid economic development. Implications for China's long-term economic development are thereby raised.

  3. Study on the Driving Forces of Rocky Desertification in Guizhou Province Based on Variation Coefficient Method

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the driving forces of rocky desertification in Guizhou Province. [Method] Based on GIS and RS technology, the main driving forces of rocky desertification in Guizhou Province were analyzed by means of correlation analysis and variation coefficient method, and then the distribution of rocky desertification in Guizhou Province was assessed synthetically. [Result] The main driving forces of rocky desertification in Guizhou Province were vegetation cover, rainfall, peasant incom...

  4. COMPETITIVENESS IN SERVICES, DRIVING FORCE OF ECONOMIC DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    RAMONA PÎRVU

    2012-12-01

    Full Text Available The competitiveness of a nation is ensured by the profitable activity of firms. They strengthen their position in the domestic and international markets through global strategies whose purpose is to increase productivity and maintain it at a high level. For this, the company must take into account both the internal economic environment which ensures operating conditions and the external economic environment’s development. The five competitive forces determine the industry’s profitability because they configure firms’ selling prices, production costs and investments needed to be competitive in the field. The threat of new competitors limits the potential profit since they involve new production units and the opportunities for market expansion. Economic strength of the buyers and bidders attracts profits to them. Rivalry among existing competitors erodes profits by increasing costs of competition (like advertising, selling expenses or those required for research and development. The presence of substitutive goods or services limits competitors’ prices through buyers’ transfer phenomena limiting and eroding market share of industry / firm in the total production output.

  5. External force estimation and implementation in robotically assisted minimally invasive surgery.

    Science.gov (United States)

    Sang, Hongqiang; Yun, Jintian; Monfaredi, Reza; Wilson, Emmanuel; Fooladi, Hadi; Cleary, Kevin

    2017-06-01

    Robotically assisted minimally invasive surgery can offer many benefits over open surgery and laparoscopic minimally invasive surgery. However, currently, there is no force sensing and force feedback. This research was implemented using the da Vinci research kit. An external force estimation and implementation method was proposed based on dynamics and motor currents. The dynamics of the Patient Side Manipulator was modeled. The dynamic model was linearly parameterized. The estimation principle of external force was derived. The dynamic parameters were experimentally identified using a least squares method. Several experiments including dynamic parameter identification, joint torque estimation, and external force estimation were performed. The results showed that the proposed method could implement force estimation without using a force sensor. The force estimation method was proposed and implemented and experimental results showed the method worked and was feasible. This method could be used for force sensing in minimally invasive surgical robotics in the future. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Using discriminant analysis to detect intrusions in external communication for self-driving vehicles

    Directory of Open Access Journals (Sweden)

    Khattab M.Ali Alheeti

    2017-08-01

    Full Text Available Security systems are a necessity for the deployment of smart vehicles in our society. Security in vehicular ad hoc networks is crucial to the reliable exchange of information and control data. In this paper, we propose an intelligent Intrusion Detection System (IDS to protect the external communication of self-driving and semi self-driving vehicles. This technology has the ability to detect Denial of Service (DoS and black hole attacks on vehicular ad hoc networks (VANETs. The advantage of the proposed IDS over existing security systems is that it detects attacks before they causes significant damage. The intrusion prediction technique is based on Linear Discriminant Analysis (LDA and Quadratic Discriminant Analysis (QDA which are used to predict attacks based on observed vehicle behavior. We perform simulations using Network Simulator 2 to demonstrate that the IDS achieves a low rate of false alarms and high accuracy in detection.

  7. Effect of a powered drive on pushing and pulling forces when transporting bariatric hospital beds.

    Science.gov (United States)

    Wiggermann, Neal

    2017-01-01

    Powered drives designed to assist with moving hospital beds are commercially available but no studies have evaluated whether they reduce the push and pull forces likely contributing to injury in caregivers. This study measured hand forces of 10 caregivers maneuvering a manual and powered bariatric bed through simulated hospital environments (hallway, elevator, and ramp). Peak push and pull forces exceeded previously established psychophysical limits for all activities with the manual bed. For the powered bed, peak forces were significantly (p forces between 38% (maneuvering into elevator) and 94% (descending ramp). Powered drive also reduced stopping distance by 55%. When maneuvering, the integral of hand force was 34% lower with powered drive, but average forces during straight-line pushing did not differ between beds. Powered drive may reduce the risk of injury or the number of caregivers needed for transport. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Investigation of Multiscale Non-equilibrium Flow Dynamics Under External Force Field

    CERN Document Server

    Xiao, Tianbai

    2016-01-01

    The multiple scale non-equilibrium gaseous flow behavior under external force field is investigated. Both theoretical analysis based on the kinetic model equation and numerical study are presented to demonstrate the dynamic effect of external force on the flow evolution, especially on the non-equilibrium heat flux. The current numerical experiment is based on the well-balanced unified gas-kinetic scheme (UGKS), which presents accurate solutions in the whole flow regime from the continuum Navier-Stokes solution to the transition and free molecular ones. The heat conduction in the non-equilibrium regime due to the external forcing term is quantitatively investigated. In the lid-driven cavity flow study, due to the external force field the density distribution inside cavity gets stratified and a multiscale non-equilibrium flow transport appears in a single gas dynamic system. With the increment of external forcing term, the flow topological structure changes dramatically, and the temperature gradient, shearing s...

  9. Behind the wheel and on the map: Genetic and environmental associations between drunk driving and other externalizing behaviors.

    Science.gov (United States)

    Quinn, Patrick D; Harden, K Paige

    2013-11-01

    Drunk driving, a major contributor to alcohol-related mortality, has been linked to a variety of other alcohol-related (e.g., Alcohol Dependence, early age at first drink) and non-alcohol-related externalizing behaviors. In a sample of 517 same-sex twin pairs from the National Longitudinal Study of Adolescent Health, we examined 3 conceptualizations of the etiology of drunk driving in relation to other externalizing behaviors. A series of behavioral-genetic models found consistent evidence for drunk driving as a manifestation of genetic vulnerabilities toward a spectrum of alcohol-related and non-alcohol-related externalizing behaviors. Most notably, multidimensional scaling analyses produced a genetic "map" with drunk driving located near its center, supporting the strength of drunk driving's genetic relations with a broad range of externalizing behaviors. In contrast, nonshared environmental associations with drunk driving were weaker and more diffuse. Drunk driving may be a manifestation of genetic vulnerabilities toward a broad externalizing spectrum. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  10. Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

    Directory of Open Access Journals (Sweden)

    Luning Shi

    2014-01-01

    Full Text Available A prestress force identification method for externally prestressed concrete uniform beam based on the frequency equation and the measured frequencies is developed. For the purpose of the prestress force identification accuracy, we first look for the appropriate method to solve the free vibration equation of externally prestressed concrete beam and then combine the measured frequencies with frequency equation to identify the prestress force. To obtain the exact solution of the free vibration equation of multispan externally prestressed concrete beam, an analytical model of externally prestressed concrete beam is set up based on the Bernoulli-Euler beam theory and the function relation between prestress variation and vibration displacement is built. The multispan externally prestressed concrete beam is taken as the multiple single-span beams which must meet the bending moment and rotation angle boundary conditions, the free vibration equation is solved using sublevel simultaneous method and the semi-analytical solution of the free vibration equation which considered the influence of prestress on section rigidity and beam length is obtained. Taking simply supported concrete beam and two-span concrete beam with external tendons as examples, frequency function curves are obtained with the measured frequencies into it and the prestress force can be identified using the abscissa of the crosspoint of frequency functions. Identification value of the prestress force is in good agreement with the test results. The method can accurately identify prestress force of externally prestressed concrete beam and trace the trend of effective prestress force.

  11. Musculoskeletal modelling of muscle activation and applied external forces for the correction of scoliosis.

    Science.gov (United States)

    Curtin, Maurice; Lowery, Madeleine M

    2014-04-07

    This study uses biomechanical modelling and computational optimization to investigate muscle activation in combination with applied external forces as a treatment for scoliosis. Bracing, which incorporates applied external forces, is the most popular non surgical treatment for scoliosis. Non surgical treatments which make use of muscle activation include electrical stimulation, postural control, and therapeutic exercises. Electrical stimulation has been largely dismissed as a viable treatment for scoliosis, although previous studies have suggested that it can potentially deliver similarly effective corrective forces to the spine as bracing. The potential of muscle activation for scoliosis correction was investigated over different curvatures both with and without the addition of externally applied forces. The five King's classifications of scoliosis were investigated over a range of Cobb angles. A biomechanical model of the spine was used to represent various scoliotic curvatures. Optimization was applied to the model to reduce the curves using combinations of both deep and superficial muscle activation and applied external forces. Simulating applied external forces in combination with muscle activation at low Cobb angles (forces were applied in combination, lower levels of muscle activation or less external force was required to reduce the curvature of the spine, when compared with either muscle activation or external force applied in isolation. The results of this study suggest that activation of superficial and deep muscles may be effective in reducing spinal curvature at low Cobb angles when muscle groups are selected for activation based on the curve type. The findings further suggest the potential for a hybrid treatment involving combined muscle activation and applied external forces at larger Cobb angles.

  12. Cation charge dependence of the forces driving DNA assembly.

    Science.gov (United States)

    DeRouchey, Jason; Parsegian, V Adrian; Rau, Donald C

    2010-10-20

    Understanding the strength and specificity of interactions among biologically important macromolecules that control cellular functions requires quantitative knowledge of intermolecular forces. Controlled DNA condensation and assembly are particularly critical for biology, with separate repulsive and attractive intermolecular forces determining the extent of DNA compaction. How these forces depend on the charge of the condensing ion has not been determined, but such knowledge is fundamental for understanding the basis of DNA-DNA interactions. Here, we measure DNA force-distance curves for a homologous set of arginine peptides. All forces are well fit as the sum of two exponentials with 2.4- and 4.8-Å decay lengths. The shorter-decay-length force is always repulsive, with an amplitude that varies slightly with length or charge. The longer-decay-length force varies strongly with cation charge, changing from repulsion with Arg¹ to attraction with Arg². Force curves for a series of homologous polyamines and the heterogeneous protein protamine are quite similar, demonstrating the universality of these forces for DNA assembly. Repulsive amplitudes of the shorter-decay-length force are species-dependent but nearly independent of charge within each species. A striking observation was that the attractive force amplitudes for all samples collapse to a single curve, varying linearly with the inverse of the cation charge.

  13. The driving forces of land change in the Northern Piedmont of the United States

    Science.gov (United States)

    Auch, Roger F.; Napton, Darrell E.; Kambly, Steven; Moreland, Thomas R.; Sayler, Kristi L.

    2012-01-01

    Driving forces facilitate or inhibit land-use/land-cover change. Human driving forces include political, economic, cultural, and social attributes that often change across time and space. Remotely sensed imagery provides regional land-change data for the Northern Piedmont, an ecoregion of the United States that continued to urbanize after 1970 through conversion of agricultural and forest land covers to developed uses. Eight major driving forces facilitated most of the land conversion; other drivers inhibited or slowed change. A synergistic web of drivers may be more important in understanding land change than individual drivers by themselves.

  14. Distribution of inspiratory drive to the external intercostal muscles in humans

    Science.gov (United States)

    De Troyer, André; Gorman, Robert B; Gandevia, Simon C

    2003-01-01

    The external intercostal muscles in humans show marked regional differences in respiratory effect, and this implies that their action on the lung during breathing is primarily determined by the spatial distribution of neural drive among them. To assess this distribution, monopolar electrodes were implanted under ultrasound guidance in different muscle areas in six healthy individuals and electromyographic recordings were made during resting breathing. The muscles in the dorsal portion of the third and fifth interspace showed phasic inspiratory activity with each breath in every subject. However, the muscle in the ventral portion of the third interspace showed inspiratory activity in only three subjects, and the muscle in the dorsal portion of the seventh interspace was almost invariably silent. Also, activity in the ventral portion of the third interspace, when present, and activity in the dorsal portion of the fifth interspace were delayed relative to the onset of activity in the dorsal portion of the third interspace. In addition, the discharge frequency of the motor units identified in the dorsal portion of the third interspace averaged (mean ± s.e.m.) 11.9 ± 0.3 Hz and was significantly greater than the discharge frequency of the motor units in both the ventral portion of the third interspace (6.0 ± 0.5 Hz) and the dorsal portion of the fifth interspace (6.7 ± 0.4 Hz). The muscle in the dorsal portion of the third interspace started firing simultaneously with the parasternal intercostal in the same interspace, and the discharge frequency of its motor units was even significantly greater (11.4 ± 0.3 vs. 8.9 ± 0.2 Hz). These observations indicate that the distribution of neural inspiratory drive to the external intercostals in humans takes place along dorsoventral and rostrocaudal gradients and mirrors the spatial distribution of inspiratory mechanical advantage. PMID:12563017

  15. UNIFORM ATTRACTOR FOR NONAUTONOMOUS INCOMPRESSIBLE NON-NEWTONIAN FLUID WITH A NEW CLASS OF EXTERNAL FORCES

    Institute of Scientific and Technical Information of China (English)

    Zhao Caidi; Jia Xiaolin; Yang Xinbo

    2011-01-01

    This paper is joint with [27].The authors prove in this article the existence and reveal its structure of uniform attractor for a two-dimensional nonautonomous incompressible non-Newtonian fluid with a new class of external forces.

  16. Spatiotemporal complexity of a predator-prey system with the effect of noise and external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Rao Feng [Institute of Nonlinear Analysis, College of Mathematics and Information Science, Wenzhou University, Wenzhou 325035 (China); Wang Weiming [Institute of Nonlinear Analysis, College of Mathematics and Information Science, Wenzhou University, Wenzhou 325035 (China)], E-mail: weimingwang2003@163.com; Li Zhenqing [Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093 (China)

    2009-08-30

    In this paper, we present a spatial version of the Ivlev-type predator-prey model which contains some important factors, such as noise on predator, external periodic forcing and diffusion processes on both predator and prey. From the numerical results, we know that noise or external periodic forcing can induce instability and enhance the oscillation of the species density, and the cooperation between noise and external periodic forcing inherent to the deterministic dynamics of periodically driven models gives rise to the appearance of a rich transport phenomenology. Furthermore, we demonstrate that the spatially extended system exhibits a resonant patterns and frequency-locking phenomena. Our results show that noise and external periodic forcing play a prominent role in the predator-prey model.

  17. EXISTENCE OF INFINITE ENERGY SOLUTION TO THE INELASTIC BOLTZMANN EQUATION WITH EXTERNAL FORCE

    Institute of Scientific and Technical Information of China (English)

    Wei Jinbo; Zhang Xianwen

    2012-01-01

    In this paper,the Cauchy problem for the inelastic Boltzmann equation with external force is considered in the case of initial data with infinite energy.More precisely,under the assumptions on the bicharacteristic generated by external force,we prove the global existence of solution for small initial data compared to the local Maxwellian exp{-p|x-v|2},which has infinite mass and energy.

  18. Driving forces of Indian summer monsoon on Milankovitch and sub-Milankovitch time scales: A review

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.

    and deep water circulation changes drive the variability of southwest (SW) monsoon in the Indian subcontinent. Different forcing factors act on different time scales. Arabian Sea sediments consist of distinct fauna that are endemic to areas of upwelling...

  19. Analysis of Korean Students' International Mobility by 2-D Model: Driving Force Factor and Directional Factor

    Science.gov (United States)

    Park, Elisa L.

    2009-01-01

    The purpose of this study is to understand the dynamics of Korean students' international mobility to study abroad by using the 2-D Model. The first D, "the driving force factor," explains how and what components of the dissatisfaction with domestic higher education perceived by Korean students drives students' outward mobility to seek…

  20. Recent drying of the Fertile Crescent: natural or externally forced?

    Science.gov (United States)

    Kelley, Colin

    2014-05-01

    There has been a reduction in observed precipitation over the greater Mediterranean region since the middle of the 20th Century. Recent studies suggest that while anthropogenic forcing has already begun to assert itself in recent decades, the preponderance of the winter drying trend is attributable to the large natural multidecadal variability of the North Atlantic Oscillation (NAO), while over the eastern Mediterranean, the anthropogenic, or forced drying signal is more clearly evident. This forced drying is projected to increase during the 21st Century according to the newest global climate models and this aridification would present significant challenges for a region that is already water-stressed. Although the Fertile Crescent is historically known for its agricultural prosperity, the severity and persistence of the recent multiyear drought in Syria, directly prior to the 2011 uprising there, leads us to ask whether this is evidence of emerging global warming influence. This drought exacerbated existing water insecurity, resulting in an agricultural collapse and a mass migration of rural drought refugees to the urban areas in Syria's west. This migration followed the previous influx of Iragi refugees and combined with strong natural population growth to place a severe strain on resources. Here we examine observations of precipitation and temperature, both gridded and stations, along with simulations and projections from the newest global climate models, to estimate the forced contribution to the recent Syrian drought, and assess the uncertainty in future drying according to the models. We find that this region has experienced a long-term downward trend in precipitation, and a concomitant increase in temperature, serving to further dry the soil, and in surface pressure. We find that the shift in the distributions of three-year running means of surface pressure and precipitation due to the forcing make severe events such as the recent Syrian drought several

  1. Spatial and Temporal Dynamics in the Ionic Driving Force for GABAA Receptors

    Directory of Open Access Journals (Sweden)

    R. Wright

    2011-01-01

    Full Text Available It is becoming increasingly apparent that the strength of GABAergic synaptic transmission is dynamic. One parameter that can establish differences in the actions of GABAergic synapses is the ionic driving force for the chloride-permeable GABAA receptor (GABAAR. Here we review some of the sophisticated ways in which this ionic driving force can vary within neuronal circuits. This driving force for GABAARs is subject to tight spatial control, with the distribution of Cl− transporter proteins and channels generating regional variation in the strength of GABAAR signalling across a single neuron. GABAAR dynamics can result from short-term changes in their driving force, which involve the temporary accumulation or depletion of intracellular Cl−. In addition, activity-dependent changes in the expression and function of Cl− regulating proteins can result in long-term shifts in the driving force for GABAARs. The multifaceted regulation of the ionic driving force for GABAARs has wide ranging implications for mature brain function, neural circuit development, and disease.

  2. Drive-amplitude-modulation atomic force microscopy: From vacuum to liquids

    Directory of Open Access Journals (Sweden)

    Miriam Jaafar

    2012-04-01

    Full Text Available We introduce drive-amplitude-modulation atomic force microscopy as a dynamic mode with outstanding performance in all environments from vacuum to liquids. As with frequency modulation, the new mode follows a feedback scheme with two nested loops: The first keeps the cantilever oscillation amplitude constant by regulating the driving force, and the second uses the driving force as the feedback variable for topography. Additionally, a phase-locked loop can be used as a parallel feedback allowing separation of the conservative and nonconservative interactions. We describe the basis of this mode and present some examples of its performance in three different environments. Drive-amplutide modulation is a very stable, intuitive and easy to use mode that is free of the feedback instability associated with the noncontact-to-contact transition that occurs in the frequency-modulation mode.

  3. Urbanization: Main Driving Force in Economic Development in Coming Years

    Institute of Scientific and Technical Information of China (English)

    HuAn'gang; ZhaoBaohua; DavidKelly

    2004-01-01

    The past 25 years has seen an unprecedented exodus of rural immigrants flowing into cities or townships. Coastal China has become the main destination to take in the country's surplus farming labor forces in the rustic population; while the populous central or western provinces,

  4. Superconductor-ferromagnet bilayer under external drive: The role of vortex-antivortex matter

    Science.gov (United States)

    Frota, D. A.; Chaves, A.; Ferreira, W. P.; Farias, G. A.; Milošević, M. V.

    2016-03-01

    Using advanced Ginzburg-Landau simulations, we study the superconducting state of a thin superconducting film under a ferromagnetic layer, separated by an insulating oxide, in applied external magnetic field and electric current. The taken uniaxial ferromagnet is organized into a series of parallel domains with alternating polarization of out-of-plane magnetization, sufficiently strong to induce vortex-antivortex pairs in the underlying superconductor in absence of other magnetic field. We show the organization of such vortex-antivortex matter into rich configurations, some of which are not matching the periodicity of the ferromagnetic film. The variety of possible configurations is enhanced by applied homogeneous magnetic field, where additional vortices in the superconductor may lower the energy of the system by either annihilating the present antivortices under negative ferromagnetic domains or by lowering their own energy after positioning under positive ferromagnetic domains. As a consequence, both the vortex-antivortex reordering in increasing external field and the evolution of the energy of the system are highly nontrivial. Finally, we reveal the very interesting effects of applied dc electric current on the vortex-antivortex configurations, since resulting Lorentzian force has opposite direction for vortices and antivortices, while direction of the applied current with respect to ferromagnetic domains is of crucial importance for the interaction of the applied and the Meissner current, as well as the consequent vortex-antivortex dynamics—both of which are reflected in the anisotropic critical current of the system.

  5. The thermodynamic driving force for kinetics in general and enzyme kinetics in particular.

    Science.gov (United States)

    Pekař, Miloslav

    2015-03-16

    The thermodynamic driving force of a reaction is usually taken as the chemical potential difference between products and reactants. The forward and backward reaction rates are then related to this force. This procedure is of very limited validity, as the resulting expression contains no kinetic factor and gives little information on reaction kinetics. The transformation of the reaction rate as a function of concentration (and temperature) into a function of chemical potential should be more properly performed, as illustrated by a simple example of an enzymatic reaction. The proper thermodynamic driving force is the difference between the exponentials of the totaled chemical potentials of reactants and products.

  6. Evidence for external forcing temporal clustering of great earthquakes

    Science.gov (United States)

    Khachikyan, Galina; Zhumabayev, Beibit; Toyshiev, Nursultan; Kairatkyzy, Dina; Kaldybayev, Azamat; Nurakynov, Serik

    2016-04-01

    It is shown by Bufe and Perkins [2005, BSSA, doi:10.1785/0120040110] and Shearera and Stark [2012, PNAS, doi: 10.1073/pnas.1118525109] that clustering of great earthquakes in 1950-1965 and 2004-2011 years is highly significant, with a 0.5% probability of random occurrence. Lutikov and Rogozhin [2014, Physics of the Solid Earth] reported on a similar clustering in the end of 19th - beginning of 20ty centuries as well, when strongest earthquakes occurred in Tien Shan (1889, M=8.3; and 1911, M=8.2); Alaska (1899, M=8.0); Kashgaria (1902, M=8.2); Mongolia (1905, M=8.2); San Francisco (1906, M=8.3), China(1906, M=8.3); Columbia (1906, M=8.6). Shearera and Stark [2012] have found that clustering of great earthquakes is analogous to seismic swarms that occur for a limited time. Simultaneously, they mentioned that at present no physical mechanism has been proposed to explain possible global seismicity swarms. Our results suggest that a mechanism responsible for temporal clustering of great earthquakes could be an external one related to the processes in the whole solar system including the Sun. We pay attention that the three marked periods of great earthquake clustering are related closely to the extreme phases of the recent Solar Centennial Gleissberg Cycle, which minimums occurred around of 1913 and 2008 years, and maximum - around of 1960 year. In particular, the great earthquake clustering in 1950-1965 coincides closely with the extremely high 19th eleven year solar cycle lasting from February 1954 to October 1964, while a great earthquake clustering after 2004 year coincides closely with the recent prolonged solar minimum developing after 2000 year. Also, we demonstrate that depending on the structure and composition of the lithosphere, strongest earthquakes may prefer to occur either in high or low solar activity. In particular, data analysis for 32 strongest (M=>7.0) earthquakes occurred in 1973-2014 years in the orogeny region of Eurasia, restricted by coordinates

  7. Position and force control of a vehicle with two or more steerable drive wheels

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Unseren, M.A.

    1992-01-01

    When a vehicle with two or more steerable drive wheels is traveling in a circle, the motion of the wheels is constrained. The wheel translational velocity divided by the radius to the center of rotation must be the same for all wheels. When the drive wheels are controlled independently using position control, the motion of the wheels may violate the constraints and the wheels may slip. Consequently, substantial errors can occur in the orientation of the vehicle. A vehicle with N drive wheels has (N - 1) constraints and one degree of freedom. We have developed a new approach to the control of a vehicle with N steerable drive wheels. The novel aspect of our approach is the use of force control. To control the vehicle, we have one degree of freedom for the position on the circle and (N - 1) forces that can be used to reduce errors. Recently, Kankaanranta and Koivo developed a control architecture that allows the force and position degrees of freedom to be decoupled. In the work of Kankaanranta and Koivo the force is an exogenous input We have made the force endogenous by defining the force in terms of the errors in satisfying the rigid body kinematic constraints. We have applied the control architecture to the HERMIES-M robot and have measured a dramatic reduction in error (more than a factor of 20) compared to rations without force control.

  8. Position and force control of a vehicle with two or more steerable drive wheels

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Unseren, M.A.

    1992-11-01

    When a vehicle with two or more steerable drive wheels is traveling in a circle, the motion of the wheels is constrained. The wheel translational velocity divided by the radius to the center of rotation must be the same for all wheels. When the drive wheels are controlled independently using position control, the motion of the wheels may violate the constraints and the wheels may slip. Consequently, substantial errors can occur in the orientation of the vehicle. A vehicle with N drive wheels has (N - 1) constraints and one degree of freedom. We have developed a new approach to the control of a vehicle with N steerable drive wheels. The novel aspect of our approach is the use of force control. To control the vehicle, we have one degree of freedom for the position on the circle and (N - 1) forces that can be used to reduce errors. Recently, Kankaanranta and Koivo developed a control architecture that allows the force and position degrees of freedom to be decoupled. In the work of Kankaanranta and Koivo the force is an exogenous input We have made the force endogenous by defining the force in terms of the errors in satisfying the rigid body kinematic constraints. We have applied the control architecture to the HERMIES-M robot and have measured a dramatic reduction in error (more than a factor of 20) compared to rations without force control.

  9. Position and force control of a vehicle with two or more steerable drive wheels

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Unseren, M.A.

    1992-10-01

    When a vehicle with two or more steerable drive wheels is traveling in a circle, the motion of the wheels is constrained. The wheel translational velocity divided by the radius to the center of rotation must be the same for all wheels. When the drive wheels are controlled independently using position control, the motion of the wheels may violate the constraints and the wheels may slip. Consequently, substantial errors can occur in the orientation of the vehicle. A vehicle with N drive wheels has (N - 1) constraints and one degree of freedom. We have developed a new approach to the control of a vehicle with N steerable drive wheels. The novel aspect of our approach is the use of force control. To control the vehicle, we have one degree of freedom for the position on the circle and (N - 1) forces that can be used to reduce errors. Recently, Kankaanranta and Koivo developed a control architecture that allows the force and position degrees of freedom to be decoupled. In the work of Kankaanranta and Koivo the force is an exogenous input. We have made the force endogenous by defining the force in terms of the errors in satisfying the rigid body kinematic constraints. We have applied the control architecture to the HERMIES-III robot and have measured a dramatic reduction in error (more than a factor of 20) compared to motions without force control.

  10. Theoretical study of enhancing the piezoelectric nanogenerator's output power by optimizing the external force's shape

    Science.gov (United States)

    Xu, Qi; Qin, Yong

    2017-07-01

    The average power is one of the key parameters of piezoelectric nanogenerators (PENGs). In this paper, we demonstrate that the PENG's output can be gigantically improved by choosing driving force with an appropriate shape. When the load resistance is 100 MΩ and the driven forces have a magnitude of 19.6 nN, frequency of 10 Hz, the average power of PENG driven by square shaped force is six orders of magnitude higher than that driven by triangular shaped and sinusoidal shaped forces. These results are of importance for optimizing the average power of the PENGs in practical applications.

  11. Experimental modeling of the effect of hurricane wind forces on driving behavior and vehicle performance.

    Science.gov (United States)

    Rodriguez, Jose M; Codjoe, Julius; Osman, Osama; Ishak, Sherif; Wolshon, Brian

    2015-01-01

    While traffic planning is important for developing a hurricane evacuation plan, vehicle performance on the roads during extreme weather conditions is critical to the success of the planning process. This novel study investigates the effect of gusty hurricane wind forces on the driving behavior and vehicle performance. The study explores how the parameters of a driving simulator could be modified to reproduce wind loadings experienced by three vehicle types (passenger car, ambulance, and bus) during gusty hurricane winds, through manipulation of appropriate software. Thirty participants were then tested on the modified driving simulator under five wind conditions (ranging from normal to hurricane category 4). The driving performance measures used were heading error and lateral displacement. The results showed that higher wind forces resulted in more varied and greater heading error and lateral displacement. The ambulance had the greatest heading errors and lateral displacements, which were attributed to its large lateral surface area and light weight. Two mathematical models were developed to estimate the heading error and lateral displacements for each of the vehicle types for a given change in lateral wind force. Through a questionnaire, participants felt the different characteristics while driving each vehicle type. The findings of this study demonstrate the valuable use of a driving simulator to model the behavior of different vehicle types and to develop mathematical models to estimate and quantify driving behavior and vehicle performance under hurricane wind conditions.

  12. Rising electricity consumption: Driving forces and consequences. The case of rural Zanzibar

    Energy Technology Data Exchange (ETDEWEB)

    Winther, Tanja [Centre for Development and the Environment (SUM), Univ. of Oslo (Norway)

    2007-07-01

    The paper addresses the current, rising electricity consumption in the southern, rural locality of Zanzibar and seeks to account for the range of driving forces behind people's changed practices. The author argues that these forces are, on the one hand, determined by the availability of new technologies and through global and national institutions and influences such as Islam, commercials and changes in the governmental sector (health, education). On the other hand, the paper explores the way such influences interplay with the internal dynamics related to increasing consumption. Through an analysis of the particular character and dynamics of social and cultural life in this region, the author explains why some practices are less likely to change than other practices. For example, people in Zanzibar keep electricity (freezers and stoves) at a distance from their food. By contrast, electric light is perceived as intimately related to education, as illustrated when school children are sent to school for night classes before important exams. To which extent may general approaches to the study of energy consumption draw on this empirical case from Zanzibar? In other contexts, the patterns of people's electricity use certainly differ. In terms of sustainable energy policies, each locality has a particular set of challenges and goals, which to varying degree may be related to poverty reduction and concern for the environment. Methodologically, however, the author argues that the phenomenon of energy consumption may be studied and understood within the same framework of analysis; one that pays attention to both external and internal dynamics, the material and social aspects of technologies and the importance of power relations, gender and negotiations.

  13. Impacts of external forcing on the 20th century global warming

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The impacts of external forcing, including natural and anthropogenic, on the 20th century global warming were assessed with the use of the Grid Atmospheric Model of IAP/LASG Version 1.1.0, following the standard coordinated experiment design of the Climate Variability and Predictability (CLIVAR) International Climate of the Twentieth Century Project (C20C), Phase II. The results indicate that external forcing plays an important role in the evolution of the land surface air temperature on interannual, decadal, and interdecadal time scales, and contributes greatly to the global warming in the following two periods: the early twentieth century between the 1910s and the 1940s and the late twentieth century after the 1970s. External forcing also has strong impact on the regional temperature change during the two warming periods except for parts of the Eurasia and the North America continents. In the cooling period, however, the impact of internal variability is dominant.

  14. Malaria Vaccine Development and How External Forces Shape It: An Overview

    OpenAIRE

    Veronique Lorenz; Gabriele Karanis; Panagiotis Karanis

    2014-01-01

    The aim of this paper is to analyse the current status and scientific value of malaria vaccine approaches and to provide a realistic prognosis for future developments. We systematically review previous approaches to malaria vaccination, address how vaccine efforts have developed, how this issue may be fixed, and how external forces shape vaccine development. Our analysis provides significant information on the various aspects and on the external factors that shape malaria vaccine development...

  15. An active optimal control strategy of rotor vibrations using external forces

    Science.gov (United States)

    Zhu, W.; Castelazo, I.; Nelson, H. D.

    1989-01-01

    An active control strategy for lateral rotor vibrations using external forces is proposed. An extended state observer is used to reconstruct the full states and the unbalance distribution. An optimal controller which accommodates persistent unbalance excitation is derived with feedback of estimated states and unbalances. Numerical simulations were conducted for two separate four degree of freedom rotor systems. These simulations indicated that the proposed strategy can achieve almost complete vibration cancellation. This was shown to be true even when the number of external control forces was less than the system order so long as coordinate coupling was present. Both steady state and transient response at a constant speed are presented.

  16. Pull-in control due to Casimir forces using external magnetic fields

    CERN Document Server

    Esquivel-Sirvent, R; Cocoletzi, G H

    2009-01-01

    We present a theoretical calculation of the pull-in control in capacitive micro switches actuated by Casimir forces, using external magnetic fields. The external magnetic fields induces an optical anisotropy due to the excitation of magneto plasmons, that reduces the Casimir force. The calculations are performed in the Voigt configuration, and the results show that as the magnetic field increases the system becomes more stable. The detachment length for a cantilever is also calculated for a cantilever, showing that it increases with increasing magnetic field. At the pull-in separation, the stiffness of the system decreases with increasing magnetic field.

  17. Tuning the driving force for exciton dissociation in single-walled carbon nanotube heterojunctions

    Science.gov (United States)

    Ihly, Rachelle; Mistry, Kevin S.; Ferguson, Andrew J.; Clikeman, Tyler T.; Larson, Bryon W.; Reid, Obadiah; Boltalina, Olga V.; Strauss, Steven H.; Rumbles, Garry; Blackburn, Jeffrey L.

    2016-06-01

    Understanding the kinetics and energetics of interfacial electron transfer in molecular systems is crucial for the development of a broad array of technologies, including photovoltaics, solar fuel systems and energy storage. The Marcus formulation for electron transfer relates the thermodynamic driving force and reorganization energy for charge transfer between a given donor/acceptor pair to the kinetics and yield of electron transfer. Here we investigated the influence of the thermodynamic driving force for photoinduced electron transfer (PET) between single-walled carbon nanotubes (SWCNTs) and fullerene derivatives by employing time-resolved microwave conductivity as a sensitive probe of interfacial exciton dissociation. For the first time, we observed the Marcus inverted region (in which driving force exceeds reorganization energy) and quantified the reorganization energy for PET for a model SWCNT/acceptor system. The small reorganization energies (about 130 meV, most of which probably arises from the fullerene acceptors) are beneficial in minimizing energy loss in photoconversion schemes.

  18. Tuning the driving force for exciton dissociation in single-walled carbon nanotube heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Ihly, Rachelle; Mistry, Kevin S.; Ferguson, Andrew J.; Clikeman, Tyler T.; Larson, Bryon W.; Reid, Obadiah; Boltalina, Olga V.; Strauss, Steven H.; Rumbles, Garry; Blackburn, Jeffrey L.

    2016-04-25

    Understanding the kinetics and energetics of interfacial electron transfer in molecular systems is crucial for the development of a broad array of technologies, including photovoltaics, solar fuel systems and energy storage. The Marcus formulation for electron transfer relates the thermodynamic driving force and reorganization energy for charge transfer between a given donor/acceptor pair to the kinetics and yield of electron transfer. Here we investigated the influence of the thermodynamic driving force for photoinduced electron transfer (PET) between single-walled carbon nanotubes (SWCNTs) and fullerene derivatives by employing time-resolved microwave conductivity as a sensitive probe of interfacial exciton dissociation. For the first time, we observed the Marcus inverted region (in which driving force exceeds reorganization energy) and quantified the reorganization energy for PET for a model SWCNT/acceptor system. The small reorganization energies (about 130 meV, most of which probably arises from the fullerene acceptors) are beneficial in minimizing energy loss in photoconversion schemes.

  19. Impacts of Human Activity on Biodiversity——An Approach to Driving Force indicators

    Institute of Scientific and Technical Information of China (English)

    RichardDawson; CaoZhiping

    2005-01-01

    The impact of human activity on biodiversity is very complicated, making it difficult to design practical indicators for assessment. Currently, state and response indicators are listed within Chapter 15 of Agenda 21, but no mention is made of driving force indicators and how they relate to biodiversity protection. This paper represents an effort to identify and then operationalize the idea of driving force indicators at national level. Five human induced factors affecting blodiversity were discussed: (a) habitat toss and fragmentation; (b) overexploitation of resources; (c) species introduction; (d) pollution; and (e) climate change. From these five factors, a subset was selected to serve as possible driving force indicators: (1) habitat loss, (2) the ratio of exotic species to indigenous ones, and (3) the change in pollution status. Although the three indicators are relatively simple, they cover the most important human impacts on biodiversity and offer the potential for further redefinition and ultimate use within the spirit of biodiversity protection.

  20. CRISPR as a driving force: the Model T of biotechnology.

    Science.gov (United States)

    Mariscal, Carlos; Petropanagos, Angel

    2016-06-01

    The CRISPR system for gene editing can break, repair, and replace targeted sections of DNA. Although CRISPR gene editing has important therapeutic potential, it raises several ethical concerns. Some bioethicists worry CRISPR is a prelude to a dystopian future, while others maintain it should not be feared because it is analogous to past biotechnologies. In the scientific literature, CRISPR is often discussed as a revolutionary technology. In this paper we unpack the framing of CRISPR as a revolutionary technology and contrast it with framing it as a value-threatening biotechnology or business-as-usual. By drawing on a comparison between CRISPR and the Ford Model T, we argue CRISPR is revolutionary as a product, process, and as a force for social change. This characterization of CRISPR offers important conceptual clarity to the existing debates surrounding CRISPR. In particular, conceptualizing CRISPR as a revolutionary technology structures regulatory goals with respect to this new technology. Revolutionary technologies have characteristic patterns of implementation, entrenchment, and social impact. As such, early identification of technologies as revolutionary may help construct more nuanced and effective ethical frameworks for public policy.

  1. Preliminary Experimental Results for Indirect Vector-Control of Induction Motor Drives with Forced Dynamics

    Directory of Open Access Journals (Sweden)

    Jan Vittek

    2003-01-01

    Full Text Available The contribution presents an extension of indirect vector control of electric drives employing induction motors to 'Forced Dynamic Control'. This method of control offers an accurate realisation of dynamic response profiles, which can be selected by the user. The developed system can be integrated into a drive with a shaft position encoder or a shaft sensoriess drive, in which only the stator currents are measured. The applied stator voltages are determined by a computed inverter switching algorithm. Simulation results and preliminary experimental results for indirect vector control of an idle running induction motor indicate good agreement with the theoretical predictions.

  2. Force control compensation method with variable load stiffness and damping of the hydraulic drive unit force control system

    Science.gov (United States)

    Kong, Xiangdong; Ba, Kaixian; Yu, Bin; Cao, Yuan; Zhu, Qixin; Zhao, Hualong

    2016-05-01

    Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this

  3. External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction.

    Science.gov (United States)

    Yang, Jian; Cong, Weijian; Chen, Yang; Fan, Jingfan; Liu, Yue; Wang, Yongtian

    2014-02-21

    The clinical value of the 3D reconstruction of a coronary artery is important for the diagnosis and intervention of cardiovascular diseases. This work proposes a method based on a deformable model for reconstructing coronary arteries from two monoplane angiographic images acquired from different angles. First, an external force back-projective composition model is developed to determine the external force, for which the force distributions in different views are back-projected to the 3D space and composited in the same coordinate system based on the perspective projection principle of x-ray imaging. The elasticity and bending forces are composited as an internal force to maintain the smoothness of the deformable curve. Second, the deformable curve evolves rapidly toward the true vascular centerlines in 3D space and angiographic images under the combination of internal and external forces. Third, densely matched correspondence among vessel centerlines is constructed using a curve alignment method. The bundle adjustment method is then utilized for the global optimization of the projection parameters and the 3D structures. The proposed method is validated on phantom data and routine angiographic images with consideration for space and re-projection image errors. Experimental results demonstrate the effectiveness and robustness of the proposed method for the reconstruction of coronary arteries from two monoplane angiographic images. The proposed method can achieve a mean space error of 0.564 mm and a mean re-projection error of 0.349 mm.

  4. Numerical-analytical investigation into impact pipe driving in soil with dry friction. Part II: Deformable external medium

    CERN Document Server

    Aleksandrova, Nadezhda

    2013-01-01

    Under analysis is travel of P-waves in an elastic pipe partly embedded in soil with dry friction. The mathematical formulation of the problem on impact pipe driving in soil is based on the model of axial vibration of an elastic bar, considering lateral resistance described using the law of solid dry friction. The author solves problems on axial load on pipe in interaction with external elastic medium, and compares the analytical and numerical results obtained with and without accounting for the external medium deformability.

  5. Symmetries, conservation laws, and time reversibility for Hamiltonian systems with external forces

    NARCIS (Netherlands)

    Schaft, A.J. van der

    1983-01-01

    A system theoretic framework is given for the description of Hamiltonian systems with external forces and partial observations of the state. It is shown how symmetries and conservation laws can be defined within this framework. A generalization of Noether's theorem is obtained. Finally a precise def

  6. Real-Time Control of Humanoid Robots Considering External Forces on Upper Part of the Body

    Science.gov (United States)

    Inomata, Kentaro; Shigemori, Yo; Uchimura, Yutaka

    Recently, the demand for the practical use of service robots has risen significantly because of acceleration of demographic aging, and a humanoid robot is one of the promising form factors of service robots. When a humanoid robot is used by a human in a real environment, the robot needs to be designed by taking into account the various external forces that act on the robot. Thus far, most of the walking humanoid robots have been mainly controlled by the conventional ZMP method to maintain a stable walking posture. However, the conventional ZMP method can not be used to handle the various external forces that act on the upper part of the humanoid robot body. To overcome these problems, in this paper, we propose a novel control method, which we called 3DZMP and pZMP, for a humanoid robot to react to the external force on the upper part of the body. The 3DZMP is defined as the point in three-dimensional space at which the moment about all axes is zero. 3DZMP can prevent the rotation of a humanoid robot. The pZMP is defined as the point corresponding to the orthographic projection of the 3DZMP on a plane. pZMP is used to evaluate the stability of 3DZMP. We implemented the proposed method on a prototype robot and verified that the robot gained the capability to react to external forces that could not be handled by the conventional ZMP method.

  7. A piecewise-integration method for simulating the influence of external forcing on climate

    Institute of Scientific and Technical Information of China (English)

    Zhifu Zhang; Chongjian Qiu; Chenghai Wang

    2008-01-01

    Climate drift occurs in most general circulation models (GCMs) as a result of incomplete physical and numerical representation of the complex climate system,which may cause large uncertainty in sensitivity experiments evaluating climate response to changes in external forcing.To solve this problem,we propose a piecewise-integration method to reduce the systematic error in climate sensitivity studies.The observations are firstly assimilated into a numerical model by using the dynamic relaxation technique to relax to the current state of atmosphere,and then the assimilated fields are continuously used to reinitialize the simulation to reduce the error of climate simulation.When the numerical model is integrated with changed external forcing,the results can be split into two parts,background and perturbation fields,and the background is the state before the external forcing is changed.The piecewise-integration method is used to continuously reinitialize the model with the assimilated field,instead of the background.Therefore,the simulation error of the model with the external forcing can be reduced.In this way,the accuracy of climate sensitivity experiments is greatly improved.Tests with a simple low-order spectral model show that this approach can significantly reduce the uncertainty of climate sensitivity experiments.

  8. Design and Synthesis of Distillation Systems using a Driving Force Based Approach

    DEFF Research Database (Denmark)

    Bek-Pedersen, Erik; Gani, Rafiqul

    2004-01-01

    A new integrated framework for synthesis, design and operation of distillation-based separation schemes is presented here. This framework is based on the driving force approach, which provides a measure of the differences in chemical/physical properties between two co-existing phases in a separat...

  9. Emission of greenhouse gases 1990-2010. Trends and driving forces

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-03-01

    Emissions of greenhouse gases in Norway from 1990-2010 - trends and driving forces, a report that presents emission trends in Norway with the analysis of the main drivers and trends, and a review and analysis of the effectiveness of implemented measures.(Author)

  10. Disruptive Innovations as a Driving Force for the Change of Wireless Telecommunication Infrastructures

    DEFF Research Database (Denmark)

    Kyoseva, Tsvetoslava; Poulkov, Vladimir; Mihaylov, Mihail Rumenov

    2014-01-01

    Innovations are the driving force for fundamental changes and development of future generation telecommunication networks. When considering innovations as drivers for the development of next generation telecommunication networks an important question is whether an innovative emerging technology...... would cause a disruption requiring fundamental change of the infrastructure or will it will only catalyze its evolution. This paper describes the major characteristics of disruptive innovations as a driving force for fundamental changes in existing telecommunications infrastructures. By analyzing...... the current trends in mobile communications, we reason that the emergence of new telecommunication architectures and infrastructures is inevitable. An important consideration in the analysis is the driving role of disruptive technologies for the future of telecommunications. Based on a model for evaluating...

  11. Fingerprints in the clouds: identifying expected cloud responses to external forcing

    Science.gov (United States)

    Marvel, K.; Zelinka, M. D.

    2013-12-01

    Changes in cloud properties in response to external forcing affect the radiation budget of the Earth, which in turn affects the equilibrium climate response. Reconciling modeled and observed cloud trends is therefore crucial in understanding climate sensitivity and the response to anthropogenic increases in greenhouse gas concentrations. While cloud responses differ greatly across models, errors in the locations of large-scale features can obscure even those physical processes that are robust across multiple models. We propose a method to track changes in cloud height, amount, and vertical profile across multiple models, and show that certain characteristics of the response are present in most models. This allows us to calculate a multidimensional fingerprint representing the characteristic cloud response to external forcing. We show how this fingerprint changes when various relevant forcing terms are included or excluded, and differentiate between models with high and low climate sensitivities. This represents an important first step toward detection and attribution of cloud trends.

  12. Design considerations of electromagnetic force in a direct drive permanent magnet brushless motor

    Science.gov (United States)

    Chen, H. S.; Tsai, M. C.

    2008-04-01

    In this paper, a numerical study of electromagnetic force associated with the width of stator teeth, width of rotor back iron, and slot opening for a ten-pole nine-slot direct drive permanent magnet brushless motor is presented. The study calculates the amplitude of the electromagnetic force on the rotating rotor by using the finite-element method. The results show that the amplitude of electromagnetic force, which may cause the noise and vibration of motors, changes with the variation of these above mentioned three factors. The relationship between the considerations of output torque and the minimization of noise and vibration is also established in this paper.

  13. Driving-forces model on individual behavior in scenarios considering moving threat agents

    Science.gov (United States)

    Li, Shuying; Zhuang, Jun; Shen, Shifei; Wang, Jia

    2017-09-01

    The individual behavior model is a contributory factor to improve the accuracy of agent-based simulation in different scenarios. However, few studies have considered moving threat agents, which often occur in terrorist attacks caused by attackers with close-range weapons (e.g., sword, stick). At the same time, many existing behavior models lack validation from cases or experiments. This paper builds a new individual behavior model based on seven behavioral hypotheses. The driving-forces model is an extension of the classical social force model considering scenarios including moving threat agents. An experiment was conducted to validate the key components of the model. Then the model is compared with an advanced Elliptical Specification II social force model, by calculating the fitting errors between the simulated and experimental trajectories, and being applied to simulate a specific circumstance. Our results show that the driving-forces model reduced the fitting error by an average of 33.9% and the standard deviation by an average of 44.5%, which indicates the accuracy and stability of the model in the studied situation. The new driving-forces model could be used to simulate individual behavior when analyzing the risk of specific scenarios using agent-based simulation methods, such as risk analysis of close-range terrorist attacks in public places.

  14. External forces influence the elastic coupling effects during cargo transport by molecular motors.

    Science.gov (United States)

    Berger, Florian; Keller, Corina; Klumpp, Stefan; Lipowsky, Reinhard

    2015-02-01

    Cellular transport is achieved by the cooperative action of molecular motors which are elastically linked to a common cargo. When the motors pull on the cargo at the same time, they experience fluctuating elastic strain forces induced by the stepping of the other motors. These elastic coupling forces can influence the motors' stepping and unbinding behavior and thereby the ability to transport cargos. Based on a generic single motor description, we introduce a framework that explains the response of two identical molecular motors to a constant external force. In particular, we relate the single motor parameters, the coupling strength and the external load force to the dynamics of the motor pair. We derive four distinct transport regimes and determine how the crossover lines between the regimes depend on the load force. Our description of the overall cargo dynamics takes into account relaxational displacements of the cargo caused by the unbinding of one motor. For large forces and weak elastic coupling these back-shifts dominate the displacements. To develop an intuitive understanding about motor cooperativity during cargo transport, we introduce a time scale for load sharing. This time scale allows us to predict how the regulation of single motor parameters influences the cooperativity. As an example, we show that up-regulating the single motor processivity enhances load sharing of the motor pair.

  15. Active contour external force using vector field convolution for image segmentation.

    Science.gov (United States)

    Li, Bing; Acton, Scott T

    2007-08-01

    Snakes, or active contours, have been widely used in image processing applications. Typical roadblocks to consistent performance include limited capture range, noise sensitivity, and poor convergence to concavities. This paper proposes a new external force for active contours, called vector field convolution (VFC), to address these problems. VFC is calculated by convolving the edge map generated from the image with the user-defined vector field kernel. We propose two structures for the magnitude function of the vector field kernel, and we provide an analytical method to estimate the parameter of the magnitude function. Mixed VFC is introduced to alleviate the possible leakage problem caused by choosing inappropriate parameters. We also demonstrate that the standard external force and the gradient vector flow (GVF) external force are special cases of VFC in certain scenarios. Examples and comparisons with GVF are presented in this paper to show the advantages of this innovation, including superior noise robustness, reduced computational cost, and the flexibility of tailoring the force field.

  16. A Study of the Effect of the Fringe Fields on the Electrostatic Force in Vertical Comb Drives

    Directory of Open Access Journals (Sweden)

    Else Gallagher

    2014-10-01

    Full Text Available The equation that describes the relationship between the applied voltage and the resulting electrostatic force within comb drives is often used to assist in choosing the dimensions for their design. This paper re-examines how some of these dimensions—particularly the cross-sectional dimensions of the comb teeth—affect this relationship in vertical comb drives. The electrostatic forces in several vertical comb drives fabricated for this study were measured and compared to predictions made with four different mathematical models in order to explore the amount of complexity required within a model to accurately predict the electrostatic forces in the comb drives.

  17. Position Control of Linear Synchronous Motor Drives with Exploitation of Forced Dynamics Control Principles

    Directory of Open Access Journals (Sweden)

    Jan Vittek

    2004-01-01

    Full Text Available Closed-loop position control of mechanisms directly driven by linear synchronous motors with permanent magnets is presented. The control strategy is based on forced dynamic control, which is a form of feedback linearisation, yielding a non-liner multivariable control law to obtain a prescribed linear speed dynamics together with the vector control condition of mutal orthogonality between the stator current and magnetic flux vectors (assuming perfect estimates of the plant parameters. Outer position control loop is closed via simple feedback with proportional gain. Simulations of the design control sysstem, including the drive with power electronic switching, predict the intended drive performance.

  18. Theoretical critical value curve and driving force formation of ecological migration in the arid land

    Institute of Scientific and Technical Information of China (English)

    ZHU Zi'an; ZHANG Xiaolei

    2006-01-01

    The features of the fragile eco-environment of the arid land decide that its capacity of disturbance-resistance is lower. The natural desert oases in the arid land are in mosaic patches distributed in a wide Gobi desert. The population distribution is greatly dependent on water resources. The population is characterized with dispersed distribution, simple production and living style, and poverty and remoteness. The reason why the ecological migrations are carried out lies in the ecological problems. "Ecological degradation" is the main driving force of the ecological migration. Then, the strength of the driving force depends on the degree of ecological degradation. Hence, whether to carry out ecological migration depends on the extent of ecological degradation.Theoretically, the critical value curve for calculating ecological migration in the arid land is put forward through comprehensive research of relative problems of ecology, economics etc., combined with the ecological migration experience in the arid land, and based on the features of the arid environment. In this article, with this curve, the theoretical research and some practice of the ecological migration have been done from the perspective of natural behavior and governmental behavior of the driving force formation of ecological migration. It analyses the active driving force (factors) and negative forces (factors), and points out the timing and steps of implementing the ecological migration in the arid land. The theoretical curve embodies certain originality and applicability,which provides a quantitative method for evaluating 196the degree of ecological degradation and the theoretical base for implementing ecological migration projects.

  19. Enhanced Diffusion of Molecular Motors in the Presence of Adenosine Triphosphate and External Force

    Science.gov (United States)

    Shinagawa, Ryota; Sasaki, Kazuo

    2016-06-01

    The diffusion of a molecular motor in the presence of a constant external force is considered on the basis of a simple theoretical model. The motor is represented by a Brownian particle moving in a series of parabolic potentials placed periodically on a line, and the potential is switched stochastically from one parabola to another by a chemical reaction, which corresponds to the hydrolysis or synthesis of adenosine triphosphate (ATP) in motor proteins. It is found that the diffusion coefficient as a function of the force exhibits peaks. The mechanism of this diffusion enhancement and the possibility of observing it in F1-ATPase, a biological rotary motor, are discussed.

  20. Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models

    Science.gov (United States)

    Alvarez-Nodarse, R.; Quintero, N. R.; Mertens, F. G.

    2014-10-01

    A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.

  1. Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models.

    Science.gov (United States)

    Alvarez-Nodarse, R; Quintero, N R; Mertens, F G

    2014-10-01

    A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.

  2. External Periodic Force Control of a Single-Degree-of-Freedom Vibroimpact System

    Directory of Open Access Journals (Sweden)

    Jingyue Wang

    2013-01-01

    Full Text Available A single-degree-of-freedom mechanical model of vibro-impact system is established. Bifurcation and chaos in the system are revealed with the time history diagram, phase trajectory map, and Poincaré map. According to the bifurcation and chaos of the actual vibro-impact system, the paper puts forward external periodic force control strategy. The method of controlling chaos by external periodic force feedback controller is developed to guide chaotic motions towards regular motions. The stability of the control system is also analyzed especially by theory. By selecting appropriate feedback coefficients, the unstable periodic orbits of the original chaotic orbit can be stabilized to the stable periodic orbits. The effectiveness of this control method is verified by numerical simulation.

  3. Quantifying internally generated and externally forced climate signals at regional scales in CMIP5 models

    Science.gov (United States)

    Lyu, Kewei; Zhang, Xuebin; Church, John A.; Hu, Jianyu

    2015-11-01

    The Earth's climate evolves because of both internal variability and external forcings. Using Coupled Model Intercomparison Project Phase 5 (CMIP5) models, here we quantify the ratio of externally forced variance to total variance on interannual and longer time scales for regional surface air temperature (SAT) and sea level, which depends on the relative strength of externally forced signal compared to internal variability. The highest ratios are found in tropical areas for SAT but at high latitudes for sea level over the historical period when ocean dynamics and global mean thermosteric contributions are considered. Averaged globally, the ratios over a fixed time interval (e.g., 30 years) are projected to increase during the 21st century under the business-as-usual scenario (RCP8.5). In contrast, under two mitigation scenarios (RCP2.6 and RCP4.5), the ratio declines sharply by the end of the 21st century for SAT, but only declines slightly or stabilizes for sea level, indicating a slower response of sea level to climate mitigation.

  4. Propagation of the state change induced by external forces in local interactions

    Science.gov (United States)

    Lu, Jianjun; Tokinaga, Shozo

    2016-10-01

    This paper analyses the propagation of the state changes of agents that are induced by external forces applied to a plane. In addition, we propose two models for the behavior of the agents placed on a lattice plane, both of which are affected by local interactions. We first assume that agents are allowed to move to another site to maximise their satisfaction. Second, we utilise a model in which the agents choose activities on each site. The results show that the migration (activity) patterns of agents in both models achieve stability without any external forces. However, when we apply an impulsive external force to the state of the agents, we then observe the propagation of the changes in the agents' states. Using simulation studies, we show the conditions for the propagation of the state changes of the agents. We also show the propagation of the state changes of the agents allocated in scale-free networks and discuss the estimation of the agents' decisions in real state changes. Finally, we discuss the estimation of the agents' decisions in real state temporal changes using economic and social data from Japan and the United States.

  5. Dynamic tensile forces drive collective cell migration through three-dimensional extracellular matrices

    Science.gov (United States)

    Gjorevski, Nikolce; S. Piotrowski, Alexandra; Varner, Victor D.; Nelson, Celeste M.

    2015-01-01

    Collective cell migration drives tissue remodeling during development, wound repair, and metastatic invasion. The physical mechanisms by which cells move cohesively through dense three-dimensional (3D) extracellular matrix (ECM) remain incompletely understood. Here, we show directly that migration of multicellular cohorts through collagenous matrices occurs via a dynamic pulling mechanism, the nature of which had only been inferred previously in 3D. Tensile forces increase at the invasive front of cohorts, serving a physical, propelling role as well as a regulatory one by conditioning the cells and matrix for further extension. These forces elicit mechanosensitive signaling within the leading edge and align the ECM, creating microtracks conducive to further migration. Moreover, cell movements are highly correlated and in phase with ECM deformations. Migrating cohorts use spatially localized, long-range forces and consequent matrix alignment to navigate through the ECM. These results suggest biophysical forces are critical for 3D collective migration. PMID:26165921

  6. Hydrodynamic Forces on Macromolecules Protruding from Lipid Bilayers Due to External Liquid Flows.

    Science.gov (United States)

    Jönsson, Peter; Jönsson, Bengt

    2015-11-24

    It has previously been observed that an externally applied hydrodynamic shear flow above a fluid lipid bilayer can change the local concentration of macromolecules that are associated with the lipid bilayer. The external liquid flow results in a hydrodynamic force on molecules protruding from the lipid bilayer, causing them to move in the direction of the flow. However, there has been no quantitative study about the magnitude of these forces. We here use finite element simulations to investigate how the magnitude of the external hydrodynamic forces varies with the size and shape of the studied macromolecule. The simulations show that the hydrodynamic force is proportional to the effective hydrodynamic area of the studied molecule, Ahydro, multiplied by the mean hydrodynamic shear stress acting on the membrane surface, σhydro. The parameter Ahydro depends on the size and shape of the studied macromolecule above the lipid bilayer and scales with the cross-sectional area of the molecule. We also investigate how hydrodynamic shielding from other surrounding macromolecules decreases Ahydro when the surface coverage of the shielding macromolecules increases. Experiments where the protein streptavidin is anchored to a supported lipid bilayer on the floor of a microfluidic channel were finally performed at three different surface concentrations, Φ = 1%, 6%, and 10%, where the protein is being moved relative to the lipid bilayer by a liquid flow through the channel. From photobleaching measurements of fluorescently labeled streptavidin we found the experimental drift data to be within good accuracy of the simulated results, less than 12% difference, indicating the validity of the results obtained from the simulations. In addition to giving a deeper insight into how a liquid flow can affect membrane-associated molecules in a lipid bilayer, we also see an interesting potential of using hydrodynamic flow experiments together with the obtained results to study the size and

  7. Environmental technology: legislation as a driving force for development; Miljoeteknologi: lovverket som drivkraft for utviklingen

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    Technology development providing a reduced pressure on the environment is necessary for a sustainable development. In order to promote such a development in technology, it is important to know which driving forces and barriers influence these processes. Factors contributing to the development of seven technologies are studied, and in general these regulations have played a bigger role for the development than 'pure market forces'. For many participants it is important to be one step ahead of the regulations, i.e. expected regulations are equally important as factual ones in driving the technology development. Simultaneously it is important that the authorities cooperate with the business when introducing new regulations. This will increase acceptance for the regulations and facilitate the necessary adjustments. The most important barrier in the development and use of the technologies studied is probably the lack of demand.

  8. Application of Laser Ranging and VLBI Data to a Study of Plate Tectonic Driving Forces

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The conditions under which changes in plate driving or resistive forces associated with plate boundary earthquakes are measurable with laser ranging or very long base interferometry were investigated. Aspects of plate forces that can be characterized by such measurements were identified. Analytic solutions for two dimensional stress diffusion in a viscoelastic plate following earthquake faulting on a finite fault, finite element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting, and quantitative constraints from modeling of global intraplate stress on the magnitude of deviatoric stress in the lithosphere are among the topics discussed.

  9. Finite Element Analysis of the Vertical Levitation Force in an Electrostatic MEMS Comb Drive Actuator

    Science.gov (United States)

    Wooldridge, J.; Blackburn, J.; Muniz-Piniella, A.; Stewart, M.; Shean, T. A. V.; Weaver, P. M.; Cain, M. G.

    2013-11-01

    A vertical levitation electrostatic comb drive actuator was manufactured for the purpose of measuring piezoelectric coefficients in small-scale materials and devices. Previous modelling work on comb drive levitation has focussed on control of the levitation in standard poly-silicon devices in order to minimize effects on lateral modes of operation required for the accelerometer and gyroscope applications. The actuator developed in this study was manufactured using a 20 μm electroplated Ni process with a 25 μm trench created beneath the released structure through chemical wet etching. A finite element analysis using ZINC was used to model electrostatic potential around a cross section of one static and one movable electrode, from which the net levitation force per unit electrode was calculated. The model was first verified using the electrode geometry from previously studied systems, and then used to study the variation of force as a function of decreasing substrate-electrode distance. With the top electrode surfaces collinear the calculated force density is 0.00651 epsilon0V2Mμm-1, equivalent to a total force for the device of 36.4 μN at an applied voltage of VM=100 V, just 16% larger than the observed value. The measured increase in force with distance was smaller than predicted with the FEA, due to the geometry of the device in which the electrodes at the anchored ends of the supporting spring structure displace by a smaller amount than those at the centre.

  10. Electronic structure and driving forces in {beta}-cyclodextrin: Diclofenac inclusion complexes

    Energy Technology Data Exchange (ETDEWEB)

    Bogdan, Diana [National Institute for Research and Development of Isotopic and Molecular Technologies, Donath street 71-103, 400293 Cluj-Napoca (Romania); Morari, C. [National Institute for Research and Development of Isotopic and Molecular Technologies, Donath street 71-103, 400293 Cluj-Napoca (Romania)]. E-mail: cristim@s3.itim-cj.ro

    2007-07-02

    We investigate the geometry and electronic structure for complexes of {beta}-cyclodextrin with diclofenac using DFT calculations. The effect of solvent is explicitly taken into account. This investigation allows us to draw meaningful conclusions upon the stability of the complex and the nature of the driving forces leading to the complexation process. In particular we emphasize the role of the water, by pointing out the changes in the solvent's electronic structure for different docking geometries.

  11. Understanding Driving Forces and Implications Associated with the Land Use and Land Cover Changes in Portugal

    Directory of Open Access Journals (Sweden)

    Bruno M. Meneses

    2017-02-01

    Full Text Available Understanding the processes of land use and land cover changes (LUCC and the associated driving forces is important for achieving sustainable development. This paper presents the LUCC in Portugal at the regional level (NUTS II from 1995 to 2010 and discusses the main driving forces and implications associated with these LUCC. The main objectives of this work are: (a to quantify the land use and land cover (LUC types (level I of LUC cartography by NUT II in Portugal for the years 1995, 2007 and 2010; (b to assess the spatio-temporal LUCC; and (c to identify and discuss the main driving forces of LUCC and corresponding implications based on correlations and Principal Components Analysis. The results revealed large regional and temporal LUCC and further highlighted the different and sometimes opposite time trends between neighboring regions. By associating driving forces to LUCC, different influences at the regional level were observed, namely LUCC into agriculture land derived from the construction of dams (Alentejo region, or the conversion of coniferous forest into eucalypt forest (Centre region associated with increased gross value added (GVA and employment in industry and forestry. Temporal differentiation was also observed, particularly in the settlements that expanded between 1995 and 2007 due to the construction of large infrastructures (e.g., highways, industrial complexes, or buildings, which is reflected on employment in industry and construction and respective GVA. However, certain LUCC have implications, particularly in energy consumption, for which different behavior between regions can be highlighted in this analysis, but also on land-use sustainability.

  12. Alien plant invasions in South Africa: driving forces and the human dimension

    CSIR Research Space (South Africa)

    Le Maitre, David C

    2004-01-01

    Full Text Available secondary driving forces ? Human population growth and migration Population increases lead to greater demands for food and materials. These demands are met by increasing productivity throughfertilization,adoptionofnewspecies,andbyincreasing the area under... production.1,35,37,48 Where demands cannot be met, people tend to migrate, taking propagules of their custom- ary food and medicinal plant species with them31,49 and inadver- tently carrying invasive species. ? Expanding network of international trade...

  13. The Effects of External Focus of Attention on Shoulder Muscle Activities during Forehand Drive in Table Tennis

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Hatami

    2016-06-01

    Full Text Available Objective: The aim of this study was to evaluate the impact of the external focus of attention on the rotator cuff muscle activity for the timely hit forehand drive by table tennis players. Methods: Twelve professional table tennis players with mean age of 26.5 years voluntarily participated in this study. The electrical activities of the muscles of the shoulder girdle using M.A 300 machine and bipolar electrodes surface under two conditions .First with external focus of attention and then without such attention were recorded, first without any guidance blows forehand drive was carried out by subjects (without focus. Then such subject was asked to focus their attention on the area marked for the ball landing (external focus of attention.      Muscle activities in both preparation and tapping phases were analyzed the three –dimensional (200 Hz, Vicon, with four camera series T motion analysis system was used to obtain the data. Data was analyzed by running reported measures ANOVA at a significance level of p0.05 but the different between the intensity of muscle activity was meaningful. This suggests that there is a mutual influence between the two attention factors and muscles (p=0.03, that is, orientation can have a significant effect on the severity of muscle contraction. Intensities of muscle contraction in the preparation and tapping were different (p<0.05. Conclusion: On the forehand drive technique, the anterior deltoid muscle has the most activity. The type of focus and attention had a significant impact on the change of activity of muscles relative to each other, and the greatest impact is on the reduction of activity of the infraspinatus muscle. This type of focus delays fatigue and results in an increase in the efficiency of neuromuscular in the activities of skills.

  14. Spatiotemporal Modeling of Urban Growth Predictions Based on Driving Force Factors in Five Saudi Arabian Cities

    Directory of Open Access Journals (Sweden)

    Abdullah F. Alqurashi

    2016-08-01

    Full Text Available This paper investigates the effect of four driving forces, including elevation, slope, distance to drainage and distance to major roads, on urban expansion in five Saudi Arabian cities: Riyadh, Jeddah, Makkah, Al-Taif and Eastern Area. The prediction of urban probabilities in the selected cities based on the four driving forces is generated using a logistic regression model for two time periods of urban change in 1985 and 2014. The validation of the model was tested using two approaches. The first approach was a quantitative analysis by using the Relative Operating Characteristic (ROC method. The second approach was a qualitative analysis in which the probable urban growth maps based on urban changes in 1985 is used to test the performance of the model to predict the probable urban growth after 2014 by comparing the probable maps of 1985 and the actual urban growth of 2014. The results indicate that the prediction model of 2014 provides a reliable and consistent prediction based on the performance of 1985. The analysis of driving forces shows variable effects over time. Variables such as elevation, slope and road distance had significant effects on the selected cities. However, distance to major roads was the factor with the most impact to determine the urban form in all five cites in both 1985 and 2014.

  15. Spatiotemporal Variation of Driving Forces for Settlement Expansion in Different Types of Counties

    Directory of Open Access Journals (Sweden)

    Guanglong Dong

    2015-12-01

    Full Text Available Understanding the process of settlement expansion and the spatiotemporal variation of driving forces is the foundation of rational and specific planning for sustainable development. However, little attention has been paid to the spatiotemporal differences of driving forces among different counties, especially when they are representatives of different development types. This study used Guanyun, Kunshan and Changshu as case studies, and binary logistic regression was employed. The results showed that the expansion rates of Kunshan and Changshu were 5.55 and 3.93 times higher than that of Guanyun. The combinations and relative importance of drivers varied with counties and periods. The change in the number of driving forces can be divided into three stages: increasing stage, decreasing stage, and stable stage. In the relatively developed counties, Kunshan and Changshu, the importance of population is decreased, while it remain an important factor in the less developed county, Guanyun. In addition, the effect of GDP stays the same in Kunshan while it becomes the most important factor in Changshu. The distance to the main road and the distance to town are increasingly important in Kunshan and Guanyun, and distance to town has been the only common factor in the last period, indicating the discrepancy is increased. The relative importance of distance to a lake in Kunshan and Changshu increased, reflecting the role of increasing tourism in accelerating settlement expansion.

  16. Determination of External Forces in Alpine Skiing Using a Differential Global Navigation Satellite System

    Directory of Open Access Journals (Sweden)

    Erich Müller

    2013-08-01

    Full Text Available In alpine ski racing the relationships between skier kinetics and kinematics and their effect on performance and injury-related aspects are not well understood. There is currently no validated system to determine all external forces simultaneously acting on skiers, particularly under race conditions and throughout entire races. To address the problem, this study proposes and assesses a method for determining skier kinetics with a single lightweight differential global navigation satellite system (dGNSS. The dGNSS kinetic method was compared to a reference system for six skiers and two turns each. The pattern differences obtained between the measurement systems (offset ± SD were −26 ± 152 N for the ground reaction force, 1 ± 96 N for ski friction and −6 ± 6 N for the air drag force. The differences between turn means were small. The error pattern within the dGNSS kinetic method was highly repeatable and precision was therefore good (SD within system: 63 N ground reaction force, 42 N friction force and 7 N air drag force allowing instantaneous relative comparisons and identification of discriminative meaningful changes. The method is therefore highly valid in assessing relative differences between skiers in the same turn, as well as turn means between different turns. The system is suitable to measure large capture volumes under race conditions.

  17. Monsoonal Responses to External Forcings over the Past Millennium: A Model Study (Invited)

    Science.gov (United States)

    Liu, J.; Wang, B.

    2009-12-01

    The climate variations related to Global Monsoon (GM) and East Asian summer monsoon (EASM) rainfall over the past 1000 years were investigated by analysis of a pair of millennium simulations with the coupled climate model named ECHO-G. The free run was generated using fixed external (annual cycle) forcing, while the forced run was obtained using time-varying solar irradiance variability, greenhouse gases (CO2 and CH4) concentration and estimated radiative effect of volcanic aerosols. The model results indicate that the centennial-millennial variation of the GM and EASM is essentially a forced response to the external radiative forcings (insolation, volcanic aerosols, and greenhouse gases). The GM strength responds more directly to the effective solar forcing (insolation plus radiative effect of the volcanoes) when compared to responses of the global mean surface temperature on centennial timescale. The simulated GM precipitation in the forced run exhibits a significant quasi-bi-centennial oscillation. Weak GM precipitation was simulated during the Little Ice Age (1450-1850) with three weakest periods concurring with the Spörer, Maunder, and Dalton Minimum of solar activity. Conversely, strong GM was simulated during the model Medieval Warm Period (ca. 1030-1240). Before the industrial period, the natural variation in effective solar forcing reinforces the thermal contrasts both between the ocean and continent and between the northern and southern hemispheres, resulting in millennium-scale variation and the quasi-bi-centennial oscillation of the GM. The prominent upward trend in the GM precipitation occurring in the last century and the remarkably strengthening of the global monsoon in the period of 1961-1990 appear unprecedented and owed possibly in part to the increase of atmospheric carbon dioxide concentration. The EASM has the largest meridional extent (5oN-55oN) among all the regional monsoons on globe. Thus, the EASM provides an unique opportunity for

  18. Force rebalance control for a MEMS gyroscope using ascending frequency drive and generalized PI control

    Directory of Open Access Journals (Sweden)

    He Chun-Hua

    2016-01-01

    Full Text Available This paper has proposed a novel force rebalance control method for a MEMS gyroscope using ascending frequency drive and generalized PI control. Theoretical analyses of ascending frequency drive and force rebalance control methods are illustrated in detail. Experimental results demonstrate that the electrical anti-resonant peaks are located at the frequency responses in the RFD system, which seriously deteriorates the original response characteristics. However, they are eliminated in the AFD system, and the electrical coupling signal is also suppressed. Besides, as for the force rebalance control system, the phase margins approximate to 60deg, gain margins are larger than 13dB, and sensitivity margins are smaller than 3.2dB, which validates the control system is stable and robust. The bandwidth of the force rebalance control system is measured to be about 103.2Hz, which accords with the simulation result. The bias instability and angle random walk are evaluated to be 1.65deg/h and 0.06deg/√h, respectively, which achieves the tactical level.

  19. Regional diversity of agricultural labor productivity and its driving force in east China

    Institute of Scientific and Technical Information of China (English)

    Liu Ziqiang; Li Jing; Lu Qi

    2009-01-01

    China's eastern area is at middle and later stage of industrialization during which the relation between ur ban and rural areas,industry and agriculture appears maladjusted The main problems are shrinkage in agricultural somparative earning and lack of driving force of agricultural development.Based on calculating agricultural labor productivity in east China from 1996 to 2005,this paper analyzes contributing degree of motive forces of agriculture develop in ten provinces and cities of east China applying GCA (Grey correlative analysis).The results show that there is no absolute correspondence between the level of industrialization and agricultural labor productivity in Chi,na's cotstern area.There is no synchronous development between industry and agricultural labor productivity in some areas.Fertilizer and agricultural machinery input had high contributing degree for ten years; however,contributing degree in land and irrigation work input was low.Non-materialization inputs became the leading role in most provinc,es and cities' increase of agricultural labor productivity.Modern agricultural development need non-materializationinputs as primary motive.force,at the same time,direct material input and facility input as guaranteed function.Forsome reasons,agricultural development is characterized by "more direct material input,less facility input" in east China now.Optimal driving force model of future agricultural development in east China is that non-materializatior inputs are dominant that perfected facilitv input are guarantee,and that certain substance inputs are necessary.

  20. Vortical flows in strongly coupled Yukawa liquids under external forcing - A molecular dynamics approach

    Science.gov (United States)

    Ganesh, Rajaraman; Charan, Harish

    2016-07-01

    Understanding vortical flows under external forcing in two dimensional (2D) fluids is a fundamental paradigm for structure formation in driven, dissipative systems. Considering Yukawa liquid as a prototype for strongly correlated or strongly coupled plasmas characterized by coupling strength (Γ, the ratio of average potential to kinetic energy per particle) and screening parameter (κ, ratio of mean inter-particle distance to shielding length), we address two important problems: 1. Onset of Rayleigh Benard convection cell (RBCC) in 2D Yukawa liquids subject to gravity and external temperature gradient 2. Onset of von Karman vortices in 2D Yukawa liquid under external pressure head, using large scale, first principles molecular dynamics simulations. For typical values of (Γ,κ), existence of a critical external temperature difference is demonstrated, beyond which RBCC are seen to set in. Beyond this critical external temperature difference, the strength of the maximum convective flow velocity is shown to exhibit a new, hitherto unsuspected linear relationship with external temperature difference and with a slope independent of (Γ,κ). The time taken for the transients to settle down to a steady state RBCC τ_s, is found to be maximum close to the above said critical external temperature difference and is seen to reduce with increasing external temperature difference. For the range of values of (Γ, κ) considered here, τ_s ≃ 10 000-20 000;ω^{-1}_{pd}, where ω_{pd} is dust plasma frequency. As Γ is increased to very high values, due to strong coupling effects, RBC cells are seen to be in a transient state without attaining a steady state for as long as 100 000;ω^{-1}_{pd}, even for a very high external temperature difference. In the second part, we address the existence of universal relation between Strouhal (St) and Rayleigh (Ry) numbers for Yukawa liquid using first principles based classical molecular dynamics. The flow past an obstacle is seen to indeed

  1. Mechanisms driving variability in the ocean forcing of Pine Island Glacier

    Science.gov (United States)

    Webber, Benjamin G. M.; Heywood, Karen J.; Stevens, David P.; Dutrieux, Pierre; Abrahamsen, E. Povl; Jenkins, Adrian; Jacobs, Stanley S.; Ha, Ho Kyung; Lee, Sang Hoon; Kim, Tae Wan

    2017-02-01

    Pine Island Glacier (PIG) terminates in a rapidly melting ice shelf, and ocean circulation and temperature are implicated in the retreat and growing contribution to sea level rise of PIG and nearby glaciers. However, the variability of the ocean forcing of PIG has been poorly constrained due to a lack of multi-year observations. Here we show, using a unique record close to the Pine Island Ice Shelf (PIIS), that there is considerable oceanic variability at seasonal and interannual timescales, including a pronounced cold period from October 2011 to May 2013. This variability can be largely explained by two processes: cumulative ocean surface heat fluxes and sea ice formation close to PIIS; and interannual reversals in ocean currents and associated heat transport within Pine Island Bay, driven by a combination of local and remote forcing. Local atmospheric forcing therefore plays an important role in driving oceanic variability close to PIIS.

  2. Streamwise-body-force-model for rapid simulation combining internal and external flow fields

    Directory of Open Access Journals (Sweden)

    Cui Rong

    2016-10-01

    Full Text Available A streamwise-body-force-model (SBFM is developed and applied in the overall flow simulation for the distributed propulsion system, combining internal and external flow fields. In view of axial stage effects, fan or compressor effects could be simplified as body forces along the streamline. These body forces which are functions of local parameters could be added as source terms in Navier-Stokes equations to replace solid boundary conditions of blades and hubs. The validation of SBFM with uniform inlet and distortion inlet of compressors shows that pressure performance characteristics agree well with experimental data. A three-dimensional simulation of the integration configuration, via a blended wing body aircraft with a distributed propulsion system using the SBFM, has been completed. Lift coefficient and drag coefficient agree well with wind tunnel test results. Results show that to reach the goal of rapid integrated simulation combining internal and external flow fields, the computational fluid dynamics method based on SBFM is reasonable.

  3. Novel bursting patterns in a Van der pol-Duffing oscillator with slow varying external force

    Science.gov (United States)

    Yu, Yue; Zhao, Min; Zhang, Zhengdi

    2017-09-01

    In this paper, we investigate the emergence of bursting dynamics with complex waveforms and their relation to periodic behavior in typical Van der pol-Duffing equation with fifth order polynomial stiffness nonlinearity, when the external force changes slowly with the variation of time. We exploit bifurcation characteristics of the fast subsystem using the slowly changing periodic excitation as a bifurcation parameter to show how the bursting oscillations are created in this model. We also identify that some regimes of bursting patterns are related to codimension two bifurcation type over a wide range of parameters. A subsequent two-parameter continuation reveals a transition in the bursting behavior from fold/fold hysteresis cycle to sup-Hopf/sup-Hopf or limit point cycle/sub-Hopf bursting type. Furthermore, the effects of external forcing item on bursting oscillations are investigated. For instance, the time interval between two adjacent spikes of bursting oscillations is dependent on the forcing frequency. Some numerical simulations are included to illustrate the validity of our study.

  4. Technique of optimization of minimum temperature driving forces in the heaters of regeneration system of a steam turbine unit

    Science.gov (United States)

    Shamarokov, A. S.; Zorin, V. M.; Dai, Fam Kuang

    2016-03-01

    At the current stage of development of nuclear power engineering, high demands on nuclear power plants (NPP), including on their economy, are made. In these conditions, improving the quality of NPP means, in particular, the need to reasonably choose the values of numerous managed parameters of technological (heat) scheme. Furthermore, the chosen values should correspond to the economic conditions of NPP operation, which are postponed usually a considerable time interval from the point of time of parameters' choice. The article presents the technique of optimization of controlled parameters of the heat circuit of a steam turbine plant for the future. Its particularity is to obtain the results depending on a complex parameter combining the external economic and operating parameters that are relatively stable under the changing economic environment. The article presents the results of optimization according to this technique of the minimum temperature driving forces in the surface heaters of the heat regeneration system of the steam turbine plant of a K-1200-6.8/50 type. For optimization, the collector-screen heaters of high and low pressure developed at the OAO All-Russia Research and Design Institute of Nuclear Power Machine Building, which, in the authors' opinion, have the certain advantages over other types of heaters, were chosen. The optimality criterion in the task was the change in annual reduced costs for NPP compared to the version accepted as the baseline one. The influence on the decision of the task of independent variables that are not included in the complex parameter was analyzed. An optimization task was decided using the alternating-variable descent method. The obtained values of minimum temperature driving forces can guide the design of new nuclear plants with a heat circuit, similar to that accepted in the considered task.

  5. Nature of the coupling between neural drive and force-generating capacity in the human quadriceps muscle.

    Science.gov (United States)

    Hug, François; Goupille, Clément; Baum, Daniel; Raiteri, Brent J; Hodges, Paul W; Tucker, Kylie

    2015-11-22

    The force produced by a muscle depends on both the neural drive it receives and several biomechanical factors. When multiple muscles act on a single joint, the nature of the relationship between the neural drive and force-generating capacity of the synergistic muscles is largely unknown. This study aimed to determine the relationship between the ratio of neural drive and the ratio of muscle force-generating capacity between two synergist muscles (vastus lateralis (VL) and vastus medialis (VM)) in humans. Twenty-one participants performed isometric knee extensions at 20 and 50% of maximal voluntary contractions (MVC). Myoelectric activity (surface electromyography (EMG)) provided an index of neural drive. Physiological cross-sectional area (PCSA) was estimated from measurements of muscle volume (magnetic resonance imaging) and muscle fascicle length (three-dimensional ultrasound imaging) to represent the muscles' force-generating capacities. Neither PCSA nor neural drive was balanced between VL and VM. There was a large (r = 0.68) and moderate (r = 0.43) correlation between the ratio of VL/VM EMG amplitude and the ratio of VL/VM PCSA at 20 and 50% of MVC, respectively. This study provides evidence that neural drive is biased by muscle force-generating capacity, the greater the force-generating capacity of VL compared with VM, the stronger bias of drive to the VL.

  6. A Digital Map From External Forcing to the Final Surface Warming Pattern and its Seasonal Cycle

    Science.gov (United States)

    Cai, M.

    2015-12-01

    Historically, only the thermodynamic processes (e.g., water vapor, cloud, surface albedo, and atmospheric lapse rate) that directly influence the top of the atmosphere (TOA) radiative energy flux balance are considered in climate feedback analysis. One of my recent research areas is to develop a new framework for climate feedback analysis that explicitly takes into consideration not only the thermodynamic processes that the directly influence the TOA radiative energy flux balance but also the local dynamical (e.g., evaporation, surface sensible heat flux, vertical convections etc) and non-local dynamical (large-scale horizontal energy transport) processes in aiming to explain the warming asymmetry between high and low latitudes, between ocean and land, and between the surface and atmosphere. In the last 5-6 years, we have developed a coupled atmosphere-surface climate feedback-response analysis method (CFRAM) as a new framework for estimating climate feedback and sensitivity in coupled general circulation models with a full physical parameterization package. In the CFRAM, the isolation of partial temperature changes due to an external forcing alone or an individual feedback is achieved by solving the linearized infrared radiation transfer model subject to individual energy flux perturbations (external or due to feedbacks). The partial temperature changes are addable and their sum is equal to the (total) temperature change (in the linear sense). The CFRAM is used to isolate the partial temperature changes due to the external forcing, due to water vapor feedback, clouds, surface albedo, local vertical convection, and non-local atmospheric dynamical feedbacks, as well as oceanic heat storage. It has been shown that seasonal variations in the cloud feedback, surface albedo feedback, and ocean heat storage/dynamics feedback, directly caused by the strong annual cycle of insolation, contribute primarily to the large seasonal variation of polar warming. Furthermore, the

  7. Different types of scaling in the dynamics of period–doubling maps under external periodic driving

    Directory of Open Access Journals (Sweden)

    N. Yu. Ivank’ov

    2000-01-01

    Full Text Available Based on the renormalization group approach developed by Kuznetsov and Pikovsky (Phys. Lett., A140, 1989, 166 several types of scaling are discussed, which can be observed in a neighborhood of Feigenbaum’s critical point at small amplitudes of the driving. The type of scaling behavior depends on a structure of binary representation of the frequency parameter: F-scaling (Feigenbaum’s for finite binary fractions, P- and Q-scaling (periodic and quasiperiodic for periodic binary fractions, and S-scaling (statistical for non-periodic binary fractions. All types of scaling are illustrated by parameter-plane diagrams for the rescaled Lyapunov exponent.

  8. Land use change and its driving forces in alluvial-plain oasis

    Science.gov (United States)

    Xiao, Luxiang; Zhang, Zengxiang; Chen, Xi; Luo, Geping; Wen, Qingke

    2007-11-01

    Land use change and its driving factors are hot topics of global change research, and also important topics of sustainable development. This paper selected a small area in alluvial plain oasis in Xinjiang Autonomous region of China as the study area. Using Landsat TM data of 1987, 1998 and 2004, the dynamic process of the spatial-temporal characteristics of land use changes were analyzed to improve understanding and to find the driving forces of land use changes so that sustainable land utilization could be practiced. During the 17 years salt-alkali tolerant cropland, cereal cropland, vegetable-fruit land, and shrubbery, had decreased remarkably by 78.59%, 85.95%, 92.13%, 68.43%, respectively. Cotton-liquorice land, grape-hop land, planted forest, residential area in town, residential area in village, and saline-alkaline field had increased dramatically. The increased percentage received the value of 2432.11%, 10103.18%, 889.91%, 222.45%, 96.00%, 44.18%, respectively. By the logistic regression, the main driving factors were derived for each land use type. The advance of technology (fertilizer input, irrigation quota, and animal labor et al.) and market (unit are yield net) were the main driving factors. Policy, in a higher level, influenced the land use dynamics for all the land use changes.

  9. A Stability Criterion for Time-Delay Tension Leg Platform Systems Subjected to External Force

    Institute of Scientific and Technical Information of China (English)

    Chen-Yuan CHEN; Chien-wen SHEN; Cheng-Wu CHEN; Kevin Fong-Rey LIU; Ming-Jen CHENG

    2009-01-01

    Stability analysis plays a central role in nonlinear system theory and engineering application.Over the past few yeats,the stability analysis of fuzzy systems has been proposed and there are many successful applications in practical engineering.Therefore,in this paper firstly proposed is the stability analysis on oceanic structure by fuzzy models.In the present study,Takagi-Sugeno (T-S) fuzzy model is proposed for a time delay tension leg platform (TLP) system subjected to an external wave force.In terms of stability analysis,linear matrix inequality (LMI) conditions are derived via Lyapunov theory to guarantee the stability of the TLP system.

  10. A simple method to construct soliton-like solution of the general KdV equation with external force

    Institute of Scientific and Technical Information of China (English)

    JiefangZHANG; FengminWU

    2000-01-01

    A simple and direct method is described to construct the soliton-like solution for the general KdV equation with external force. Crucial to the method is the assumption that the solution chosen is a special truncated expansion.

  11. Study of deformation of droplet in external force field by using liquid-gas model of lattice-gas

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, Ken-ichi; Watanabe, Tadashi [Japan Atomic Energy Research Inst., Center for Promotion of Computational Science and Engineering, Tokai, Ibaraki (Japan)

    2000-10-01

    The deformation of the droplet by the external force which is assumed to be gravity is studied by using the liquid-gas model of lattice-gas. Two types of liquid-gas models, one is the minimal model and the other is the maximal model, which are distinguished from each other by the added long-range interactions are used for the simulation of the droplet deformation. The difference of the droplet deformation between the maximal model and the minimal model was observed. While the droplet of the minimal model elongates in the direction of the external force, the droplet of the maximal model elongates in the perpendicular direction to the external force. Therefore the droplet deformation in the external force field of the maximal model is more similar to the droplet deformation which is observed in experiments than that of the minimal model. (author)

  12. Influence of an external magnetic field on forced turbulence in a swirling flow of liquid metal

    CERN Document Server

    Gallet, Basile; Mordant, Nicolas

    2009-01-01

    We report an experimental investigation on the influence of an external magnetic field on forced 3D turbulence of liquid gallium in a closed vessel. We observe an exponential damping of the turbulent velocity fluctuations as a function of the interaction parameter N (ratio of Lorentz force over inertial terms of the Navier-Stokes equation). The flow structures develop some anisotropy but do not become bidimensional. From a dynamical viewpoint, the damping first occurs homogeneously over the whole spectrum of frequencies. For larger values of N, a very strong additional damping occurs at the highest frequencies. However, the injected mechanical power remains independent of the applied magnetic field. The simultaneous measurement of induced magnetic field and electrical potential differences shows a very weak correlation between magnetic field and velocity fluctuations. The observed reduction of the fluctuations is in agreement with a previously proposed mechanism for the saturation of turbulent dynamos and wit...

  13. Associated decrements in rate of force development and neural drive after maximal eccentric exercise.

    Science.gov (United States)

    Farup, J; Rahbek, S K; Bjerre, J; de Paoli, F; Vissing, K

    2016-05-01

    The present study investigated the changes in contractile rate of force development (RFD) and the neural drive following a single bout of eccentric exercise. Twenty-four subjects performed 15 × 10 maximal isokinetic eccentric knee extensor contractions. Prior to and at 24, 48, 72, 96, and 168 h during post-exercise recovery, isometric RFD (30, 50 100, and 200 ms), normalized RFD [1/6,1/2, and 2/3 of maximal voluntary contraction (MVC)] and rate of electromyography rise (RER; 30, 50, and 75 ms) were measured. RFD decreased by 28-42% peaking at 48 h (P eccentric exercise. This association suggests that exercise-induced decrements in RFD can, in part, be explained decrements in neural drive. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Driving Forces and Development Strategies of China’s Agro-tourism

    Institute of Scientific and Technical Information of China (English)

    Ling’en; WANG; Shengkui; CHENG; Qingwen; MIN; Lu; HE

    2013-01-01

    In recent years, agro-tourism has sprung up all over the country, and has gradually become a new form of agricultural business and a new force of tourism development. The development of agro-tourism plays an important role in enriching the agricultural industry forms, increasing farmers’ income, promoting the optimization and upgrading of rural industrial structure, and expanding the field of the tourism section. This paper firstly introduces domestic and foreign agro-tourism development and current research situations. Then it analyses the development background of China’s agro-tourism from the perspective of market demand, urbanization and transformation of rural economic structure. Based on analysis, it summarizes models of driving force of China’s agro-tourism: regional traffic driven, city driven, scenic spot driven, and monopolistic resource-driven. According to these four driving force types, development strategies are put forward: Characteristic product development for regional traffic driven model; in-depth theme development for city driven model; interactive development for scenic spot driven model; brand development for resource driven model; priority development for integrated driven model. It is expected to provide reference and guidance for healthy and sustainable development of China’s agro-tourism.

  15. Analysis of Externality of Rural Labor Force Flow in Central and Western Regions of China and Benefit Compensation

    Institute of Scientific and Technical Information of China (English)

    Xin; LI; Haijing; HU

    2013-01-01

    According to the theories of institutional economics and development economics,the positive and negative externality of rural labor force flowing from central and western regions and into eastern regions of China were analyzed,and then it was proposed that it is necessary to positive externality,rather than take"household register"measures to solve the problem simply.

  16. Bidirectional transport by molecular motors: enhanced processivity and response to external forces.

    Science.gov (United States)

    Müller, Melanie J I; Klumpp, Stefan; Lipowsky, Reinhard

    2010-06-02

    Intracellular transport along cytoskeletal filaments is often mediated by two teams of molecular motors that pull on the same cargo and move in opposite directions along the filaments. We have recently shown theoretically that this bidirectional transport can be understood as a stochastic tug-of-war between the two motor teams. Here, we further develop our theory to investigate the experimentally accessible dynamic behavior of cargos transported by strong motors such as kinesin-1 or cytoplasmic dynein. By studying the run and binding times of such a cargo, we show that the properties of biological motors, such as the large ratio of stall/detachment force and the small ratio of superstall backward/forward velocity, are favorable for bidirectional cargo transport, leading to fast motion and enhanced diffusion. In addition, cargo processivity is shown to be strongly enhanced by transport via several molecular motors even if these motors are engaged in a tug-of-war. Finally, we study the motility of a bidirectional cargo under force. Frictional forces arising, e.g., from the viscous cytoplasm, lead to peaks in the velocity distribution, while external forces as exerted, e.g., by an optical trap, lead to hysteresis effects. Our results, in particular our explicit expressions for the cargo binding time and the distance of the peaks in the velocity relation under friction, are directly accessible to in vitro as well as in vivo experiments.

  17. External Load Affects Ground Reaction Force Parameters Non-uniformly during Running in Weightlessness

    Science.gov (United States)

    DeWitt, John; Schaffner, Grant; Laughlin, Mitzi; Loehr, James; Hagan, R. Donald

    2004-01-01

    Long-term exposure to microgravity induces detrimefits to the musculcskdetal system (Schneider et al., 1995; LeBlanc et al., 2000). Treadmill exercise is used onboard the International Space Station as an exercise countermeasure to musculoskeletal deconditioning due to spaceflight. During locomotive exercise in weightlessness (0G), crewmembers wear a harness attached to an external loading mechanism (EL). The EL pulls the crewmember toward the treadmill, and provides resistive load during the impact and propulsive phases of gait. The resulting forces may be important in stimulating bone maintenance (Turner, 1998). The EL can be applied via a bungee and carabineer clip configuration attached to the harness and can be manipulated to create varying amounts of load levels during exercise. Ground-based research performed using a vertically mounted treadmill found that peak ground reaction forces (GRF) during running at an EL of less than one body weight (BW) are less than those that occur during running in normal gravity (1G) (Davis et al., 1996). However, it is not known how the GRF are affected by the EL in a true OG environment. Locomotion while suspended may result in biomechanics that differ from free running. The purpose of this investigation was to determine how EL affects peak impact force, peak propulsive force, loading rate, and impulse of the GRF during running in 0G. It was hypothesized that increasing EL would result in increases in each GRF parameter.

  18. Experimental verification of an equivalent circuit for the characterization of electrothermal micropumps: high pumping velocities induced by the external inductance at driving voltages below 5 V.

    Science.gov (United States)

    Stubbe, Marco; Gyurova, Anna; Gimsa, Jan

    2013-02-01

    Electrothermal micropumps (ETμPs) use local heating to create conductivity and permittivity gradients in the pump medium. In the presence of such gradients, an external AC electric field influences smeared spatial charges in the bulk of the medium. When there is also a symmetry break, the field-charge interaction results in an effective volumetric force resulting in medium pumping. The advantages of the ETμP principle are the absence of moving parts, the opportunity to passivate all the pump structures, homogeneous pump-channel cross-sections, as well as force plateaus in broad frequency ranges. The ETμPs consisted of a DC-heating element and AC field electrodes arranged in a 1000 μm × 250 μm × 60 μm (length × width × height) channel. They were processed as platinum structures on glass carriers. An equivalent-circuit diagram allowed us to model the frequency-dependent pumping velocities of passivated and nonpassivated ETμPs, which were measured at medium conductivities up to 1.0 S/m in the 300 kHz to 52 MHz frequency range. The temperature distributions within the pumps were controlled by thermochromic beads. Under resonance conditions, an additional inductance induced a tenfold pump-velocity increase to more than 50 μm/s at driving voltages of 5 V(rms). A further miniaturization of the pumps is viewed as quite feasible.

  19. Influence of external forcings on abrupt millennial-scale climate changes: a statistical modelling study

    Science.gov (United States)

    Mitsui, Takahito; Crucifix, Michel

    2016-07-01

    The last glacial period was punctuated by a series of abrupt climate shifts, the so-called Dansgaard-Oeschger (DO) events. The frequency of DO events varied in time, supposedly because of changes in background climate conditions. Here, the influence of external forcings on DO events is investigated with statistical modelling. We assume two types of simple stochastic dynamical systems models (double-well potential-type and oscillator-type), forced by the northern hemisphere summer insolation change and/or the global ice volume change. The model parameters are estimated by using the maximum likelihood method with the NGRIP Ca^{2+} record. The stochastic oscillator model with at least the ice volume forcing reproduces well the sample autocorrelation function of the record and the frequency changes of warming transitions in the last glacial period across MISs 2, 3, and 4. The model performance is improved with the additional insolation forcing. The BIC scores also suggest that the ice volume forcing is relatively more important than the insolation forcing, though the strength of evidence depends on the model assumption. Finally, we simulate the average number of warming transitions in the past four glacial periods, assuming the model can be extended beyond the last glacial, and compare the result with an Iberian margin sea-surface temperature (SST) record (Martrat et al. in Science 317(5837): 502-507, 2007). The simulation result supports the previous observation that abrupt millennial-scale climate changes in the penultimate glacial (MIS 6) are less frequent than in the last glacial (MISs 2-4). On the other hand, it suggests that the number of abrupt millennial-scale climate changes in older glacial periods (MISs 6, 8, and 10) might be larger than inferred from the SST record.

  20. Remote sensing monitoring and driving force analysis to forest and greenbelt in Zhuhai

    Science.gov (United States)

    Yuliang Qiao, Pro.

    As an important city in the southern part of Chu Chiang Delta, Zhuhai is one of the four special economic zones which are opening up to the outside at the earliest in China. With pure and fresh air and trees shading the street, Zhuhai is a famous beach port city which is near the mountain and by the sea. On the basis of Garden City, the government of Zhuhai decides to build National Forest City in 2011, which firstly should understand the situation of greenbelt in Zhuhai in short term. Traditional methods of greenbelt investigation adopt the combination of field surveying and statistics, whose efficiency is low and results are not much objective because of artificial influence. With the adventure of the information technology such as remote sensing to earth observation, especially the launch of many remote sensing satellites with high resolution for the past few years, kinds of urban greenbelt information extraction can be carried out by using remote sensing technology; and dynamic monitoring to spatial pattern evolvement of forest and greenbelt in Zhuhai can be achieved by the combination of remote sensing and GIS technology. Taking Landsat5 TM data in 1995, Landsat7 ETM+ data in 2002, CCD and HR data of CBERS-02B in 2009 as main information source, this research firstly makes remote sensing monitoring to dynamic change of forest and greenbelt in Zhuhai by using the combination of vegetation coverage index and three different information extraction methods, then does a driving force analysis to the dynamic change results in 3 months. The results show: the forest area in Zhuhai shows decreasing tendency from 1995 to 2002, increasing tendency from 2002 to 2009; overall, the forest area show a small diminution tendency from 1995 to 2009. Through the comparison to natural and artificial driving force, the artificial driving force is the leading factor to the change of forest and greenbelt in Zhuhai. The research results provide a timely and reliable scientific basis

  1. Supersaturation is a major driving force for protein aggregation in neurodegenerative diseases

    Science.gov (United States)

    Ciryam, Prajwal; Kundra, Rishika; Morimoto, Richard I.; Dobson, Christopher M.; Vendruscolo, Michele

    2015-01-01

    The solubility of proteins is an essential requirement for their function. Yet these ubiquitous molecules can undergo aggregation when the protein homeostasis system becomes impaired. Here we ask which is the driving force for protein aggregation in the cellular environment. Emerging evidence suggests that this phenomenon arises because the native states of many proteins are inherently metastable as their cellular concentrations exceed their critical values. Such `supersaturated' proteins are strongly driven towards aggregation, and are over-represented in specific biochemical pathways associated with neurodegenerative conditions. These observations suggest that effective therapeutic approaches to combat neurodegenerative diseases could be aimed at enhancing the ability of the cell to maintain protein solubility. PMID:25636813

  2. Determination of Optimal Energy Efficient Separation Schemes based on Driving Forces

    DEFF Research Database (Denmark)

    Bek-Pedersen, Erik; Gani, Rafiqul; Levaux, O.

    2000-01-01

    A new integrated approach for synthesis, design and operation of separation schemes is presented. This integrated approach is based on driving forces that promote the desired separation for different separation techniques. A set of algorithms needed by the integrated approach for sequencing...... and design of distillation columns and for generating hybrid separation schemes are presented. The main feature of these algorithms is that they provide a 'visual' solution that also appears to be near optimal in terms of energy consumption. Several illustrative examples highlighting the application...

  3. Neutron single-particle strength in silicon isotopes: Constraining the driving forces of shell evolution

    CERN Document Server

    Stroberg, S R; Tostevin, J A; Bader, V M; Baugher, T; Bazin, D; Berryman, J S; Brown, B A; Campbell, C M; Kemper, K W; Langer, C; Lunderberg, E; Lemasson, A; Noji, S; Otsuka, T; Recchia, F; Walz, C; Weisshaar, D; Williams, S

    2015-01-01

    Shell evolution is studied in the neutron-rich silicon isotopes 36,38,40 Si using neutron single-particle strengths deduced from one-neutron knockout reactions. Configurations involving neutron excita- tions across the N = 20 and N = 28 shell gaps are quantified experimentally in these rare isotopes. Comparisons with shell model calculations show that the tensor force, understood to drive the col- lective behavior in 42 Si with N = 28, is already important in determining the structure of 40 Si with N = 26. New data relating to cross-shell excitations provide the first quantitative support for repulsive contributions to the cross-shell T = 1 interaction arising from three-nucleon forces.

  4. Three-quark interaction: The driving force in the inhomogeneous evolution equations

    Energy Technology Data Exchange (ETDEWEB)

    Bartnik, E.A.; Namyslowski, J.M.

    1984-09-01

    Using perturbative QCD on the light cone (A/sub +/ = 0 gauge), and the Brodsky-Lepage collinear projection, we make a partial-wave projection (in the l/sub z/ component) of the Weinberg equation, and find a set of evolution equations for distribution amplitudes. For l/sub z/not =0 our equations are inhomogeneous, and their solutions show an increasing QCD perturbative effect for the currently available momentum transfers. The driving force of the inhomogenous evolution equations is a three-quark irreducible interaction, which gives terms approx.(1-x)/sup 3/ in the proton's deep-inelastic structure function, breaks the SU(6) symmetry, and contributes to the deviation of the d/u ratio for proton from the value 1/2. That force couples a qq-bar pair to one transverse gluon and one Coulomb gluon.

  5. Internal and External Learning Races in ‘Born Transnationals’: What are the Driving Forces?

    Directory of Open Access Journals (Sweden)

    Jörg FREILING

    2014-03-01

    Full Text Available This paper investigates an under-researched type of ‘born transnationals’ as  young  transnational  companies.  ‘Born  transnationals’  are  equipped  with  specific governance structures that may accelerate the internationalization process based on organizational learning. In this vein, the research question of the paper is: What are the core drivers of organizational learning in case of ‘born transnationals’? Based on a model of organizational learning, we present and  check  a  model-based  set  of  structured  research  propositions  of  the  learning process  of  ‘born  transnationals’.  The  propositions  undergo  a  first  reality  check  by developing two case studies based on semi-structured interviews. Empirical  evidence  challenges  the  role  of  some  factors  (e.g.  the role  of international  experience  and  proactivity  of  entrepreneurs  well-elaborated  in literature  and  examines  whether  others  (e.g.  transactive  knowledge  play  a  pivotal role. Against this background, some of the proposed causalities were to be modified and specified. The  findings  suggest  that  organizational  learning in born transnationals requires social capital and a particular type of learning culture. Moreover, entrepreneurs are well advised to foster the transfer of knowledge among the people in the company as far as possible to turn the 'wheel of knowledge'. The  paper  portrays  a  new  type  of  born  globals, introduces  a  new  model  and  develops  first  causal  structures  in  this  context.  It identifies  and  specifies  drivers  of  learning  processes  of  the  ‘born  transnationals’ archetype.

  6. Proton-coupled electron transfers: pH-dependent driving forces? Fundamentals and artifacts.

    Science.gov (United States)

    Bonin, Julien; Costentin, Cyrille; Robert, Marc; Routier, Mathilde; Savéant, Jean-Michel

    2013-09-25

    Besides its own interest, tryptophan oxidation by photogenerated Ru complexes is one of the several examples where concerted proton-electron transfer (CPET) to water as proton acceptor endowed with a pH-dependent driving force has been invoked to explain the data. Since this notion is contrary to the very basic principles of chemical physics, it was interesting to attempt uncovering the source of this contradiction with an easily accessible substrate. Careful examination of the oxidation of the tryptophan (ethyl ester derivative) bearing a NH3(+)/NH2 group showed that there is no trace of such an unconventional H2O-CPET with a pH-dependent driving force. The reaction mechanism simply consists, with both the NH3(+) acid and NH2 basic forms of the tryptophan derivative, in a rate-determining electron-transfer step followed by deprotonation steps. The same is true with the ethyl ester-methyl amide derivative of tryptophan, whose behavior is even simpler since the molecule does not bear an acid-base group. No such unconventional H2O-CPET was found with phenol, another easily accessible substrate. It may thus be inferred that the same applies to less easily available systems in which electron transfer occurs intramolecularly. These observations help to rid the road of such artificial obstacles and improve present models of H2O-CPET reactions, a landmark towards the understanding of the role of water chains in natural systems.

  7. On arable land changes in Shandong Province and their driving forces

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The decrease of total cultivated area and the lower per capitaavailable arable land resource are now serious problems in Shandong Province, a major agricultural province in China. These problems will become more serious along with the further development of economy. In this paper,based on the statistical information at provincial and county levels, the changes of arable land in Shandong Province and their driving forces during the last 50 years are analyzed. The general changing trends of arable land and per capita available arable land are reducing, and the trends of decrease will continue when the economy is developing. The result of GIS spatial analysis shows that the change of the arable land use in Shandong Province has a regional difference. Eight variables having influences on cultivated land change are analyzed by principal component analysis. The results show that the dynamic development of economy, pressure of social system and progress of scientific techniques in agriculture are the main causes for cultivated land reduction. The principal factors which can be considered as driving forces for arable land change include per capita net living space, total population and per ha grain yield. By using regressive equation, along with analysis on population growth and economic development, cultivated areas in Shandong Province in 2005 and 2010 are predicted respectively. The predicted cultivated areas in Shandong will be 6435.47 thousand hain 2005 and 6336.23 thousand ha in 2010 respectively.

  8. Dissolution Condensation Mechanism of Stress Corrosion Cracking in Liquid Metals: Driving Force and Crack Kinetics

    Science.gov (United States)

    Glickman, Evgeny E.

    2011-02-01

    Stress corrosion cracking (SCC) in aqueous solution is driven by exothermic reactions of metal oxidation. This stimulus, as well as classical mechanisms of SCC, does not apply to SCC in liquid metals (LMs). In the framework of the dissolution-condensation mechanism (DCM), we analyzed the driving force and crack kinetics for this nonelectrochemical mode of SCC that is loosely called "liquid metal embrittlement" (LME). According to DCM, a stress-induced increase in chemical potential at the crack tip acts as the driving force for out-of-the-tip diffusion mass transfer that is fast because diffusion in LMs is very fast and surface energy at the solid-liquid interface is small. In this article, we review two versions of DCM mechanism, discuss the major physics behind them, and develop DCM further. The refined mechanism is applied then to the experimental data on crack velocity V vs stress intensity factor, the activation energy of LME, and alloying effects. It is concluded that DCM provides a good conceptual framework for analysis of a unified kinetic mechanism of LME and may also contribute to SCC in aqueous solutions.

  9. Driving forces and barriers for environmental technology development; Drivkrefter og barrierer for utvikling av miljoeteknologi

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    Driving forces and barriers behind development and usage of environmental technology is discussed, and also whether there are certain characteristics related to environmental innovations compared to other innovations in general. The development of environmental technology is in principle dominated by the same drivers and barriers as any other technology, but the order and strength of the various factors may be different. This examination as well as other empirical studies shows that regulations play a greater part for environmental technology than 'pure market forces'. To many participants it is important to be one step ahead of the regulations, i.e. the expected regulations are equally important as the factual ones in driving the technology development. Players in the business community express that it is important that the authorities cooperate with them when introducing new regulations. This will increase acceptance for the regulations and facilitate the necessary adjustments. The most important barrier in the development and use of the technologies studied is probably the lack of demand.

  10. DYNAMIC CHANGES OF THE WETLAND AND ITS DRIVING FORCES IN FUJIN REGION IN SANJIANG PLAIN, CHINA

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-Qiang; CHEN Ming; WANG Dan-Dan; ZHANG Bai; ZHANG Shu-Qing

    2005-01-01

    Wetland is a kind of key natural resources. However, the wetlands have been shrinking rapidly in Sangjiang Plain and its functions have been degrading. These all hold back the sustainable development of human communities, and lead to great change in the land use /cover (LUCC), consequently caused global changes in climate, water cycling, etc.. Taken Fujin region as a case study, spatial and temporal dynamic processes of wetland and its driving forces were analyzed from 1954 to 2000 in this paper. It showed that the wetlands had been reduced from 52×104 ha to 11×104 ha in areas during the nearly 50 years . The percentage of wetland areas reduced from 61.27% to 12.39%. On the other hand, cultivated land increased from 22×104 ha to 60×104 ha in areas. The percentage of the areas increased from 25.31% to 70.45%. Further quantitative analysis of the wetland landscape conversion characteristics and the correlation analysis between the change of wetland areas and population increase were made. The results showed that 40×104 ha wetlands had been converted to cultivated land within half of a century; the correlation between the rate of wetland loss and that of population increased is nearly -0.922. So it was concluded that the main driving force of wetland shrinkage in Fujin region was the colonization of human being.

  11. Research on driving forces for rural settlement land changes in China

    Institute of Scientific and Technical Information of China (English)

    CHEN Chun; FENG Chang-chun

    2010-01-01

    During the rapid urbanization period, the contradiction between demand for the construction land and the preservation of cultivated land for food security is getting more and more serious in China. With the urbanization the rural settlement land is increasing instead of decreasing. This paper aims at finding the driving forces for rural settlement land expansion. Based on land use change survey data (1996-2006) by the Ministry. of Land and Resources P. R. C., this paper finds that per capita area for rural settlement land is more than per capita area for city township and industrial land in each province except Tibet. Besides, rural settlement land area and per capita rural settlement land area are increasing while the rural population is decreasing in most provinces. The main problems of rural settlement land use are low efficiency, high vacancy rate, chaotic layout and illegal occupancy. Then the driving forces for rural settlement land expansion, including economic development family income, family scale, psychological factors, urbanization, transportation, lack of planning, limited circulation of dwelling-house land and imperfect social security, are explored based on above analysts. Finally, policy recommendations, in view of different influencing factors, are put forward to control the disorder expansion of rural settlement land.

  12. Driving forces behind the construction of an eco-compensation mechanism for wetlands in China

    Science.gov (United States)

    Wang, Changhai

    2016-09-01

    This research revealed important driving forces behind the construction of an eco-compensation mechanism for wetlands (DFEMW) in China. Using China's provincial panel data from 1978 to 2008, a fixed-effects model was used to analyze the impacts of agricultural production systems on wetlands. We identified three DFEMW as follows: the change of wetland resources and protection measures in China; declaration and implementation of the provincial Wetland Protection Ordinance; and wetland degradation by agricultural production systems, which necessitated the establishment of a wetland eco-compensation mechanism. In addition to the DFEMW, a significant positive correlation between wetland area and both rural population and gross agricultural production was identified, in addition to a negative correlation with chemical fertilizer usage, reservoir storage capacity, and irrigation area. The underlying reasons for the serious degradation and inadequate protection of wetlands were market failure and government failure; these were the driving forces behind the need to establish a wetland eco-compensation mechanism. From a governmental perspective, it has been difficult to rectify market failures in resource distribution and thus to prevent wetland degradation. Factors include conflicts of interest, lack of investment, effective special laws, a simple means to protect wetlands, and a multidisciplinary management system. Therefore, the key factor is the coordination of interest relationships between those who utilize wetlands and those who seek to minimize wetland degradation and effectively protect wetlands.

  13. Driving forces behind the Chinese public's demand for improved environmental safety.

    Science.gov (United States)

    Wen, Ting; Wang, Jigan; Ma, Zongwei; Bi, Jun

    2017-12-15

    Over the past decades, the public demand for improved environmental safety keeps increasing in China. This study aims to assess the driving forces behind the increasing public demand for improved environmental safety using a provincial and multi-year (1995, 2000, 2005, 2010, and 2014) panel data and the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model. The potential driving forces investigated included population size, income levels, degrees of urbanization, and educational levels. Results show that population size and educational level are positively (Pdemand for improved environmental safety. No significant impact on demand was found due to the degree of urbanization. For the impact due to income level, an inverted U-shaped curve effect with the turning point of ~140,000 CNY GDP per capita is indicated. Since per capita GDP of 2015 in China was approximately 50,000 CNY and far from the turning point, the public demand for improved environmental safety will continue rising in the near future. To meet the increasing public demand for improved environmental safety, proactive and risk prevention based environmental management systems coupled with effective environmental risk communication should be established. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Salticid predation as one potential driving force of ant mimicry in jumping spiders.

    Science.gov (United States)

    Huang, Jin-Nan; Cheng, Ren-Chung; Li, Daiqin; Tso, I-Min

    2011-05-07

    Many spiders possess myrmecomorphy, and species of the jumping spider genus Myrmarachne exhibit nearly perfect ant mimicry. Most salticids are diurnal predators with unusually high visual acuity that prey on various arthropods, including conspecifics. In this study, we tested whether predation pressure from large jumping spiders is one possible driving force of perfect ant mimicry in jumping spiders. The results showed that small non-ant-mimicking jumping spiders were readily treated as prey by large ones (no matter whether heterospecific or conspecific) and suffered high attack and mortality rates. The size difference between small and large jumping spiders significantly affected the outcomes of predatory interactions between them: the smaller the juvenile jumping spiders, the higher the predation risk from large ones. The attack and mortality rates of ant-mimicking jumping spiders were significantly lower than those of non-ant-mimicking jumping spiders, indicating that a resemblance to ants could provide protection against salticid predation. However, results of multivariate behavioural analyses showed that the responses of large jumping spiders to ants and ant-mimicking salticids differed significantly. Results of this study indicate that predation pressure from large jumping spiders might be one selection force driving the evolution of nearly perfect myrmecomorphy in spiders and other arthropods.

  15. Analysis of two phase mass transfer by logarithmic driving force based on chemical thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Nabeshima, Masahiro (Sumitomo Metal Mining Co. Ltd., Tokyo (Japan))

    1994-04-01

    In the Purex solvent extraction process in the reprocessing of spent fuel, the concentration of separated composition such as U changes continuously from very high condition to trace level. Also in most cases, water phase and organic phase continuously come in contact by counter flow operation. In this research, by the method of circulating organic phase between single liquid drop column and mixing tank, the extraction behavior of Nd and nitric acid in H[sub 2]O-NaNO[sub 3]/HNO[sub 3]-Nd(NO[sub 3])[sub 3]-100% TBP system was traced continuously, and the results of measurement and analysis are reported. The experimental equipment and the experimental condition are shown. As the driving force for two-phase mass transfer, that having chemical thermodynamic basis was introduced. It is considered that this driving force is effective for the kinetic analysis of mass transfer phenomena. Hereafter, it is necessary to confirm the more strict treatment using activity and the applicability to two-phase mass transfer phenomena. (K.I.).

  16. Influence of AC external magnetic field on guidance force relaxation between HTS bulk and NdFeB guideway

    Science.gov (United States)

    Zhang, Longcai; Wang, Suyu; Wang, Jiasu; Zheng, Jun

    2007-12-01

    Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to time-varying external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. So it is required to study whether the guidance force of the bulks is influenced by the inhomogeneity. In this paper, we studied the characteristics of the guidance force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet was used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experiment results, it was found that the guidance force was decreased with the application of the AC external magnetic field, and the decay increased with the amplitude and was almost independent of the frequency.

  17. Is climate change an unforeseen, irresistible and external factor - A force majeure in marine environmental law?

    Science.gov (United States)

    Saul, Roxanne; Barnes, Richard; Elliott, Michael

    2016-12-15

    Several environmental laws include provisions on natural causes or force majeure, which except States from their commitments if it can be proven that the failure to meet the commitment is due to factors outside their control. The European Union Marine Strategy Framework Directive (MSFD) has a pivotal role in managing EU marine waters. This paper analyses natural causes and force majeure provisions of the MFSD and other marine legislation, and addresses their interaction with climate change and its consequences, especially the effect on the obligation of ensuring seas are in Good Environmental Status. Climate change is an exogenic unmanaged pressure in that it emanates from outside the area being managed but in which the management authority has to respond to the consequences of climate change, such as sea level rise and temperature elevation, rather than its causes. It is suggested that a defence by a Member State of force majeure may be accepted if an event was proven to be due to an externality of control, irresistible and unforeseeable. The analysis contends that countering such a legal defence would centre on the fact that climate change is a well-accepted phenomenon, is foreseen with an accepted level of confidence and probability and is due to human actions. However, as yet, this has not been legally tested.

  18. Directed Self-Assembly of sub-10 nm Particles: Role of Driving Forces and Template Geometry in Packing and Ordering.

    Science.gov (United States)

    Mehraeen, Shafigh; Asbahi, Mohamed; Fuke, Wang; Yang, Joel K W; Cao, Jianshu; Tan, Mei Chee

    2015-08-11

    By comparing the magnitude of forces, a directed self-assembly mechanism has been suggested previously in which immersion capillary is the only driving force responsible for packing and ordering of nanoparticles, which occur only after the meniscus recedes. However, this mechanism is insufficient to explain vacancies formed by directed self-assembly at low particle concentrations. Utilizing experiments, and Monte Carlo and Brownian dynamics simulations, we developed a theoretical model based on a new proposed mechanism. In our proposed mechanism, the competing driving forces controlling the packing and ordering of sub-10 nm particles are (1) the repulsive component of the pair potential and (2) the attractive capillary forces, both of which apply at the contact line. The repulsive force arises from the high particle concentration, and the attractive force is caused by the surface tension at the contact line. Our theoretical model also indicates that the major part of packing and ordering of nanoparticles occurs before the meniscus recedes. Furthermore, utilizing our model, we are able to predict the various self-assembly configurations of particles as their size increases. These results lay out the interplay between driving forces during directed self-assembly, motivating a better template design now that we know the importance and the dominating driving forces in each regime of particle size.

  19. Driving biofuels in Europe. A research on the interaction between external regulation and value chain governance

    Energy Technology Data Exchange (ETDEWEB)

    Aantjes, J.C.

    2007-05-15

    To explain the unforeseen ascendancy of biofuels in the transport sector, a thorough understanding of the biofuel industry (i.e. the value chain) is crucial. Next to the industry structure, it seems that the regulatory framework surrounding the chain also contributes to the formation and structure of the biofuel industry in Europe. This assumption rests on the 2003 European Union (EU) biofuel directives for the promotion of biofuels in EU member states. With tax exemptions and reference values, the European Commission (EC) achieves to raise the amount of biofuels in transportation. The hypothesis in this thesis is that the European biofuel industry reflects a correlation between external regulation and value chain structure. More specifically, it is expected to be a mutual relation. The proposition is that value chain actors not only anticipate to the regulatory environment, they are also likely to influence decision-making on regulations in their advantage. Simply stated, value chain actors are concerned with the regulatory framework in order to enhance their position in the chain. From an empirical and theoretical point of view, this is an interesting proposition since the interaction between regulations and value chain governance receive little attention in theory. For the food industry, this approach contributes to understand the development in biofuel regulations and the European biofuel industry. Chapter Two reports the theoretical foundation of this study. The research framework rests on two rather independent streams of literature. The first part discusses 'value chain theory' and enables to examine how the biofuel value chains in Europe looks like. Among the analytical instruments of this research tradition, the role of powerful actors in controlling the value chain is elaborated in depth. The second stream is rooted in political theory and is characterized as 'political decision-making theory'. Its focus is on the formulation of

  20. Human health and the water environment: using the DPSEEA framework to identify the driving forces of disease.

    Science.gov (United States)

    Gentry-Shields, Jennifer; Bartram, Jamie

    2014-01-15

    There is a growing awareness of global forces that threaten human health via the water environment. A better understanding of the dynamic between human health and the water environment would enable prediction of the significant driving forces and effective strategies for coping with or preventing them. This report details the use of the Driving Force-Pressure-State-Exposure-Effect-Action (DPSEEA) framework to explore the linkage between water-related diseases and their significant driving forces. The DPSEEA frameworks indicate that a select group of driving forces, including population growth, agriculture, infrastructure (dams and irrigation), and climate change, is at the root cause of key global disease burdens. Construction of the DPSEEA frameworks also allows for the evaluation of public health interventions. Sanitation was found to be a widely applicable and effective intervention, targeting the driver/pressure linkage of most of the water-related diseases examined. Ultimately, the DPSEEA frameworks offer a platform for constituents in both the health and environmental fields to collaborate and commit to a common goal targeting the same driving forces.

  1. Application of laser ranging and VLBI data to a study of plate tectonic driving forces. [finite element method

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The measurability of changes in plate driving or resistive forces associated with plate boundary earthquakes by laser rangefinding or VLBI is considered with emphasis on those aspects of plate forces that can be characterized by such measurements. Topics covered include: (1) analytic solutions for two dimensional stress diffusion in a plate following earthquake faulting on a finite fault; (2) two dimensional finite-element solutions for the global state of stress at the Earth's surface for possible plate driving forces; and (3) finite-element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting.

  2. The roles of external forcing and natural variability in global warming hiatuses

    Science.gov (United States)

    Zhang, Lei

    2016-11-01

    Global mean surface temperature (GMST) rising has slowed down since late 1990s, which is referred to as the global warming hiatus. There was another global warming hiatus event during 1940s-1960s. The roles of the external forcing and the natural variability in both global warming hiatuses are explored, using EOF analysis. The first two leading EOF modes of the 5-year running mean global sea surface temperature (SST) reflect the global warming scenario (EOF1) and the interdecadal Pacific oscillation (IPO)-like natural variability (EOF2), respectively. In observation, PC2 was in its positive phase (eastern Pacific cooling) during 1940s-1960s, which contributed to the previous warming hiatus. In addition, GMST trends are found to be negative during late 1950s and 1960s in most of the CMIP5 historical runs, which implies that the external forcing also contributed to the pause in the GMST rising. It is further demonstrated that it is the natural radiative forcing (volcanic forcing) that caused the drop-down of GMST in 1960s. The current global warming hiatus has been attributed to the eastern Pacific cooling/enhanced Pacific trade winds. It is shown that the PC2 switched to its positive phase in late 1990s, and hence the IPO-like natural variability made a contribution to the slowdown of GMST rising in the past decade. It is also found that the EOF1 mode (global warming mode) of the observed SST features a smaller warming in tropical Pacific compared to the Indian Ocean and the tropical Atlantic. Such inter-basin warming contrast, which is attributed to the "ocean thermostat" mechanism, has been suggested to contribute to the intensification of Pacific trade winds since late 1990s as well. Global warming hiatuses are also found in the future projections from CMIP5 models, and the spatial pattern of the SST trends during the warming-hiatus periods exhibits an IPO-like pattern, which resembles the observed SST trends since late 1990s.

  3. Convergence Rate to Stationary Solutions for Boltzmann Equation with External Force

    Institute of Scientific and Technical Information of China (English)

    Seiji UKAI; Tong YANG; Huijiang ZHAO

    2006-01-01

    For the Boltzmann equation with an external force in the form of the gradient of a potential function in space variable, the stability of its stationary solutions as local Maxwellians was studied by S. Ukai et al. (2005) through the energy method. Based on this stability analysis and some techniques on analyzing the convergence rates to stationary solutions for the compressible Navier-Stokes equations, in this paper, we study the convergence rate to the above stationary solutions for the Boltzmann equation which is a fundamental equation in statistical physics for non-equilibrium rarefied gas. By combining the dissipation from the viscosity and heat conductivity on the fluid components and the dissipation on the non-fluid component through the celebrated H-theorem, a convergence rate of the same order as the one for the compressible Navier-Stokes is obtained by constructing some energy functionals.

  4. Solutions to Master equations of quantum Brownian motion in a general environment with external force

    Energy Technology Data Exchange (ETDEWEB)

    Roura, Albert [Los Alamos National Laboratory; Fleming, C H [UNIV OF MARYLAND; Hu, B L [UNIV OF MARYLAND

    2008-01-01

    We revisit the model of a system made up of a Brownian quantum oscillator linearly coupled to an environment made up of many quantum oscillators at finite temperature. We show that the HPZ master equation for the reduced density matrix derived earlier [B.L. Hu, J.P. Paz, Y. Zhang, Phys. Rev. D 45, 2843 (1992)] has incorrectly specified coefficients for the case of nonlocal dissipation. We rederive the QBM master equation, correctly specifying all coefficients, and determine the position uncertainty to be free of excessive cutoff sensitivity. Our coefficients and solutions are reduced entirely to contour integration for analytic spectra at arbitrary temperature, coupling strength, and cut-off. As an illustration we calculate the master equation coefficients and solve the master equation for ohmic coupling (with finite cutoff) and example supra-ohmic and sub-ohmic spectral densities. We determine the effect of an external force on the quantum oscillator and also show that our representation of the master equation and solutions naturally extends to a system of multiple oscillators bilinearly coupled to themselves and the bath in arbitrary fashion. This produces a formula for investigating the standard quantum limit which is central to addressing many theoretical issues in macroscopic quantum phenomena and experimental concerns related to low temperature precision measurements. We find that in a dissipative environment, all initial states settle down to a Gaussian density matrix whose covariance is determined by the thermal reservoir and whose mean is determined by the external force. We specify the thermal covariance for the spectral densities we explore.

  5. The role of biotic forces in driving macroevolution: beyond the Red Queen

    Science.gov (United States)

    Voje, Kjetil L.; Holen, Øistein H.; Liow, Lee Hsiang; Stenseth, Nils Chr.

    2015-01-01

    A multitude of hypotheses claim that abiotic factors are the main drivers of macroevolutionary change. By contrast, Van Valen's Red Queen hypothesis is often put forward as the sole representative of the view that biotic forcing is the main evolutionary driver. This imbalance of hypotheses does not reflect our current knowledge: theoretical work demonstrates the plausibility of biotically driven long-term evolution, whereas empirical work suggests a central role for biotic forcing in macroevolution. We call for a more pluralistic view of how biotic forces may drive long-term evolution that is compatible with both phenotypic stasis in the fossil record and with non-constant extinction rates. Promising avenues of research include contrasting predictions from relevant theories within ecology and macroevolution, as well as embracing both abiotic and biotic proxies while modelling long-term evolutionary data. By fitting models describing hypotheses of biotically driven macroevolution to data, we could dissect their predictions and transcend beyond pattern description, possibly narrowing the divide between our current understanding of micro- and macroevolution. PMID:25948685

  6. Talin2-mediated traction force drives matrix degradation and cell invasion.

    Science.gov (United States)

    Qi, Lei; Jafari, Naser; Li, Xiang; Chen, Zaozao; Li, Liqing; Hytönen, Vesa P; Goult, Benjamin T; Zhan, Chang-Guo; Huang, Cai

    2016-10-01

    Talin binds to β-integrin tails to activate integrins, regulating cell migration, invasion and metastasis. There are two talin genes, TLN1 and TLN2, encoding talin1 and talin2, respectively. Talin1 regulates focal adhesion dynamics, cell migration and invasion, whereas the biological function of talin2 is not clear and, indeed, talin2 has been presumed to function redundantly with talin1. Here, we show that talin2 has a much stronger binding to β-integrin tails than talin1. Replacement of talin2 Ser339 with Cys significantly decreased its binding to β1-integrin tails to a level comparable to that of talin1. Talin2 localizes at invadopodia and is indispensable for the generation of traction force and invadopodium-mediated matrix degradation. Ablation of talin2 suppressed traction force generation and invadopodia formation, which were restored by re-expressing talin2 but not talin1. Furthermore, re-expression of wild-type talin2 (but not talin2(S339C)) in talin2-depleted cells rescued development of traction force and invadopodia. These results suggest that a strong interaction of talin2 with integrins is required to generate traction, which in turn drives invadopodium-mediated matrix degradation, which is key to cancer cell invasion. © 2016. Published by The Company of Biologists Ltd.

  7. Effects of a compression garment on shoulder external rotation force outputs during isotonic contractions.

    Science.gov (United States)

    Tsuruike, Masaaki; Ellenbecker, Todd S

    2013-02-01

    The use of compression garments (CGs) has been advocated for performance enhancement and recovery in athletes. The effect of a CG on humeral rotation motor control has not been previously tested. The purpose of this study was to examine the isotonic contraction of external rotation (ER) of the glenohumeral joint at different force outputs to determine the effect of wearing a long sleeve CG on muscular performance. Twelve male college tennis players and 12 male college soccer players were tested for ER of the dominant shoulder during both concentric and eccentric isotonic contractions. The subjects performed 5 consecutive repetitions of both concentric and eccentric ER at 20-30% and 40-50% of maximum voluntary isometric contraction (MVIC) intensities. All subjects were tested with and without CG as well as with and without ongoing visual feedback information (OVFI). The order of CG wearing and the presence of OVFI were randomly assigned across all subjects. The results indicated a significant 3-way interaction between CG wearing and OVFI across 2 loads. Specifically, significantly different mean value of the completion time was found between OVFI and no-OVFI without CG wearing at 40-50% of MVIC, whereas no difference in the completion time was found with and without OVFI with CG wearing. Taken together, with CG wearing, athletes may have ER at 40-50% of MVIC more readily maintained by peripheral feedback without visuomotor control imposed on force outputs as compared without CG wearing.

  8. Unraveling the genetic driving forces enabling antibiotic resistance at the single cell level

    Science.gov (United States)

    Bos, Julia

    Bacteria are champions at finding ways to quickly respond and adapt to environments like the human gut, known as the epicentre of antibiotic resistance. How do they do it? Combining molecular biology tools to microfluidic and fluorescence microscopy technologies, we monitor the behavior of bacteria at the single cell level in the presence of non-toxic doses of antibiotics. By tracking the chromosome dynamics of Escherichia coli cells upon antibiotic treatment, we examine the changes in the number, localization and content of the chromosome copies within one cell compartment or between adjacent cells. I will discuss how our work pictures the bacterial genomic plasticity as a driving force in evolution and how it provides access to the mechanisms controlling the subtle balance between genetic diversity and stability in the development of antibiotic resistance.

  9. Greatest Happiness Principle in a Complex System: Maximisation versus Driving Force

    Directory of Open Access Journals (Sweden)

    Katalin Martinás

    2012-06-01

    Full Text Available From philosophical point of view, micro-founded economic theories depart from the principle of the pursuit of the greatest happiness. From mathematical point of view, micro-founded economic theories depart from the utility maximisation program. Though economists are aware of the serious limitations of the equilibrium analysis, they remain in that framework. We show that the maximisation principle, which implies the equilibrium hypothesis, is responsible for this impasse. We formalise the pursuit of the greatest happiness principle by the help of the driving force postulate: the volumes of activities depend on the expected wealth increase. In that case we can get rid of the equilibrium hypothesis and have new insights into economic theory. For example, in what extent standard economic results depend on the equilibrium hypothesis?

  10. Models for Analyzing the Driving Force of Cultivated Land Supply Change

    Institute of Scientific and Technical Information of China (English)

    LIU Yanfang; ZHANG Yuqian; XIAO Bin

    2004-01-01

    This paper focuses on a series of quantitative analysis models, such as grey relational analysis model, hierarchical cluster analysis model, principal component analysis model, linear regression model and elastic coefficient model. These models are used to analyze the comprehensive function and effect of driving forces systemically, including analysis on features, analysis for differentiating the primary and the secondary, analysis on comprehensive effects, analysis of elasticity, analysis of prediction. The primary and characteristic factors can be extracted by analysis of features and analysis for differentiating the primary and the secondary. Analysis on prediction and elasticity can predict the area of cultivated land in the future and find out which factors exert great influence on the cultivated land supply.

  11. The Impact of Evolutionary Driving Forces on Human Complex Diseases: A Population Genetics Approach

    Directory of Open Access Journals (Sweden)

    Amr T. M. Saeb

    2016-01-01

    Full Text Available Investigating the molecular evolution of human genome has paved the way to understand genetic adaptation of humans to the environmental changes and corresponding complex diseases. In this review, we discussed the historical origin of genetic diversity among human populations, the evolutionary driving forces that can affect genetic diversity among populations, and the effects of human movement into new environments and gene flow on population genetic diversity. Furthermore, we presented the role of natural selection on genetic diversity and complex diseases. Then we reviewed the disadvantageous consequences of historical selection events in modern time and their relation to the development of complex diseases. In addition, we discussed the effect of consanguinity on the incidence of complex diseases in human populations. Finally, we presented the latest information about the role of ancient genes acquired from interbreeding with ancient hominids in the development of complex diseases.

  12. Chronic inflammation-related DNA damage response: a driving force of gastric cardia carcinogenesis.

    Science.gov (United States)

    Lin, Runhua; Xiao, Dejun; Guo, Yi; Tian, Dongping; Yun, Hailong; Chen, Donglin; Su, Min

    2015-02-20

    Gastric cardia cancer (GCC) is a highly aggressive disease associated with chronic inflammation. To investigate the relationship between DNA damage response (DDR) and chronic inflammation, we collected 100 non-tumor gastric cardia specimens of Chaoshan littoral, a high-risk region for esophageal and gastric cardia cancer. A significantly higher proportion of severe chronic inflammation was found in dysplastic epithelia (80.9%) in comparison with that in non-dysplastic tissues (40.7%) (Pchronic inflammation degrees from normal to severe inflammation (Pchronic inflammation-related DNA damage response may be a driving force of gastric cardia carcinogenesis. Based on these findings, DNA damage response in non-malignant tissues may become a promising biomedical marker for predicting malignant transformation in the gastric cardia.

  13. Synchronized aromaticity as an enthalpic driving force for the aromatic Cope rearrangement.

    Science.gov (United States)

    Babinski, David J; Bao, Xiaoguang; El Arba, Marie; Chen, Bo; Hrovat, David A; Borden, Weston Thatcher; Frantz, Doug E

    2012-10-03

    We report herein experimental and theoretical evidence for an aromatic Cope rearrangement. Along with several successful examples, our data include the first isolation and full characterization of the putative intermediate that is formed immediately after the initial [3,3] sigmatropic rearrangement. Calculations at the B3LYP/6-31G(d) level of theory predict reaction energy barriers in the range 22-23 kcal/mol for the [3,3]-rearrangement consistent with the exceptionally mild reaction conditions for these reactions. The experimental and computational results support a significant enthalpic contribution of the concomitant pyrazole ring formation that serves as both a kinetic and thermodynamic driving force for the aromatic Cope rearrangement.

  14. Stress-triggered atavistic reprogramming (STAR) addiction: driving force behind head and neck cancer?

    Science.gov (United States)

    Masuda, Muneyuki; Wakasaki, Takahiro; Toh, Satoshi

    2016-01-01

    Recent results of the Cancer Genome Atlas on head and neck squamous cell carcinoma (HNSCC) revealed that HNSCC lacked predominant gain-of-function mutations in oncogenes, whereas an essential role for epigenetics in oncogenesis has become apparent. In parallel, it has gained general acceptance that cancer is considered as complex adaptive system, which evolves responding environmental selective pressures. This somatic evolution appears to proceed concurrently with the acquisition of an atavistic pluripotent state (i.e., "stemness"), which is inducible by intrinsic epigenetic reprogramming program as demonstrated by induced pluripotent stem (iPS) cells. This Nobel prize-winning discovery has markedly accelerated and expanded cancer stem cell research from the point of epigenetic reprogramming. Taken together, we hypothesize that stress-triggered atavistic reprogramming (STAR) may be the major driving force of HNSCC evolution. In this perspective, we discuss the possible mechanisms of STAR in HNSCC, focusing on recent topics of epigenetic reprogramming in developmental and cancer cell biology.

  15. Entropic transport without external force in confined channel with oscillatory boundary

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Department of Chemical Physics & Hefei National Laboratory for Physical Sciences at Microscales, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-12-28

    The dynamics of point-like Brownian particles in a periodic confined channel with oscillating boundaries has been studied. Directional transport (DT) behavior, characterized by net displacement along the horizontal direction, is observed even without external force which is necessary for the conventional DT where the boundaries are static. For typical parameter values, the average velocity V{sub t} of DT reaches a maximum with the variation of the noise intensity D, being alike to the phenomenon of stochastic resonance. Interestingly, we find that V{sub t} shows nontrivial dependences on the particle gravity G depending on the noise level. When the noise is large, V{sub t} increases monotonically with G indicating that heavier particle moves faster, while for small noise, V{sub t} shows a bell-shape dependence on G, suggesting that a particle with an intermediate weight may move the fastest. Such results were not observed for DT in a channel with static boundaries. To understand these findings, we have adopted an effective one-dimensional coarsening description, which facilitates us to introduce an effective entropic force along the horizontal direction. The average force is apparently nonzero due to the oscillatory boundary, hence leading to the net transport, and it shows similar dependences as V{sub t} on the noise intensity D and particle gravity G. The dependences of the DT behavior on other parameters describing the oscillatory channel have also been investigated, showing that DT is more pronounced for larger oscillation amplitude and frequency, and asymmetric geometry within a channel period and phase difference between neighboring periods are both necessary for the occurrence of DT.

  16. Driving force analysis of the agricultural water footprint in China based on the LMDI method.

    Science.gov (United States)

    Zhao, Chunfu; Chen, Bin

    2014-11-04

    China's water scarcity problems have become more severe because of the unprecedented economic development and population explosion. Considering agriculture's large share of water consumption, obtaining a clear understanding of Chinese agricultural consumptive water use plays a key role in addressing China's water resource stress and providing appropriate water mitigation policies. We account for the Chinese agricultural water footprint from 1990 to 2009 based on bottom up approach. Then, the underlying driving forces are decomposed into diet structure effect, efficiency effect, economic activity effect, and population effect, and analyzed by applying a log-mean Divisia index (LMDI) model. The results reveal that the Chinese agricultural water footprint has risen from the 94.1 Gm3 in 1990 to 141 Gm3 in 2009. The economic activity effect is the largest positive contributor to promoting the water footprint growth, followed by the population effect and diet structure effect. Although water efficiency improvement as a significant negative effect has reduced overall water footprint, the water footprint decline from water efficiency improvement cannot compensate for the huge increase from the three positive driving factors. The combination of water efficiency improvement and dietary structure adjustment is the most effective approach for controlling the Chinese agricultural water footprint's further growth.

  17. Vegetation Dynamics and Associated Driving Forces in Eastern China during 1999–2008

    Directory of Open Access Journals (Sweden)

    Jian Peng

    2015-10-01

    Full Text Available Vegetation is one of the most important components of the terrestrial ecosystem and, thus, monitoring the spatial and temporal dynamics of vegetation has become the key to exploring the basic process of the terrestrial ecosystem. Vegetation change studies have focused on the relationship between climatic factors and vegetation dynamics. However, correlations among the climatic factors always disturb the results. In addition, the impact of anthropogenic activities on vegetation dynamics was indeterminate. Here, vegetation dynamics in 14 provinces in Eastern China over a 10-year period was quantified to determine the driving mechanisms relating to climate and anthropogenic factors using partial correlation analysis. The results showed that from 1999 to 2008, the vegetation density increased in the whole, with spatial variations. The vegetation improvement was concentrated in the Yangtze River Delta, with the vegetation degradation concentrated in the other developed areas, such as Beijing-Tianjin-Hebei Region and the Pearl River Delta. The annual NDVI changes were mainly driven by temperature in Northeast China and the Pearl River Delta, and by precipitation in the Bohai Rim; while in the Yangtze River Delta, the driving forces of temperature and precipitation almost equaled each other.  Furthermore, the impact of anthropogenic activities on vegetation dynamics had accumulative effects in the time series, and had a phase effect on the vegetation change trend.

  18. Analysis on Electromagnetic Characteristics of Research Reactor Control Rod Drive Mechanism for Thrust Force Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Hyung; Choi, Myoung Hwan; Yu, Je Yong; Cho, Yeong Garp; Kim, Jong In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    The control rod drive mechanism (CRDM) is the part of reactor regulating system (RRS), which is located in the reactor pool top or the room below the reactor pool. The function of the CRDM is to insert, withdraw or maintain neutron absorbing material (control rod) at any required position within the reactor core, in order to the reactivity of the core. There are so many kinds of CRDM, such as magnetic-jack type, hydraulic type, rack and pinion type, chain type and linear or rotary step motor and so on. As a part of a new project, we are investigating the movable coil electromagnetic drive mechanism (MCEDM) which is new scheme for the reactor control rod adopted by China Advanced Research Reactor (CARR). To have a better knowledge of the electromagnetic and magnetic characteristics, numerical models of MCEDM are proposed. Especially in order to achieve improved thrust force, numerical magnetic field calculations for various kinds of magnetic and electromagnetic configuration have been performed. As a result, we present the improved design of MCEDM for research reactor

  19. Spatial heterogeneity of the driving forces of cropland change in China

    Institute of Scientific and Technical Information of China (English)

    LIU; Xuhua; WANG; Jinfeng; LIU; Mingliang; MENG; Bin

    2005-01-01

    By using digital satellite remote sensing data acquired in 1987―1989 and 1999―2000 and GIS combined with the natural and socio-economic data, this paper drew an integrated zonation of the cropland change and its driving forces in China. The results indicated that the cropland change in the study period was constrained by geographical factors and driven by climate change as well as socio-economic system. Moreover, the regional differences of the drivers for cropland change were significant. In the midwest of China, natural condition changes and geographical background were the main constraints and drivers, while in Eastern China, social and economic changes and economic policies were the main driving forces. The cropland loss was nationwide. The dominant factors to cause this decrease included buildup of developing area to attract foreign capital and technologies, changes of industry structure due to urban influence, the change of employment notions thanks to living standard improvement, rapid urbanization due to the expansion of cities and towns, the diminished farming net income partly because of the global warming effects, and the rapid economic growth stimulated by the convenient transportation system. These factors interact and interdepend with each other to cause the cropland loss in China recently. The reasons for the increase of cropland were primarily the cultivation and deforestation by the farmers who want to increase income. This study on the mechnism of LUCC relied on the cropland change integrated classification considering the natural or human factors both inside and outside the region, which provides a new approach to study the integrated regionalization and LUCC mechanism.

  20. Driving forces for import of waste for energy recovery in Sweden.

    Science.gov (United States)

    Olofsson, Mattias; Sahlin, Jenny; Ekvall, Tomas; Sundberg, Johan

    2005-02-01

    Between 1996 and 2002, the Swedish import of so-called yellow waste for energy recovery increased. The import mainly consisted of separated wood waste and mixes of used wood and paper and/or plastics that was combusted in district heat production plants (DHPPs). Some mixed waste was imported to waste incineration plants for energy recovery (10% of the import of yellow waste for energy recovery in 2002). The import came primarily from Germany, the Netherlands, Norway, Denmark and Finland. We identified six underlying driving forces for this recent increase of imported waste which are outlined and their interactive issues discussed. --The energy system infrastructure, which enables high energy recovery in Sweden. --The energy taxation, where high Swedish taxes on fossil fuels make relatively expensive solid biofuels the main alternative for base load production of district heat. --The quality of the waste-derived fuels, which has been higher in the exporting countries than in Sweden. --The bans on landfilling within Europe and the shortage of waste treatment capacity. --Taxes on waste management in Europe. --Gate fee differences between exporting countries and Sweden. In the future, the overall strength of these driving forces will probably be weakened. A Swedish tax on waste incineration is being investigated. In other European countries, the ambition to reach the Kyoto targets and increase the renewable electricity production could improve the competitiveness of waste-derived fuels in comparison with fossil fuels. Swedish DHPPs using waste-derived fuels will experience higher costs after the Waste Incineration Directive is fully implemented. The uncertainty about European waste generation and treatment capacity, however, might have a large influence on the future gate fees and thus also on the yellow waste import into Sweden.

  1. Quantitative attribution of major driving forces on soil organic carbon dynamics

    Science.gov (United States)

    Wu, Yiping; Liu, Shuguang; Tan, Zhengxi

    2015-03-01

    Soil organic carbon (SOC) storage plays a major role in the global carbon cycle and is affected by many factors including land use/management changes (e.g., biofuel production-oriented changes). However, the contributions of various factors to SOC changes are not well understood and quantified. This study was designed to investigate the impacts of changing farming practices, initial SOC levels, and biological enhancement of grain production on SOC dynamics and to attribute the relative contributions of major driving forces (CO2 enrichment and farming practices) using a fractional factorial modeling design. The case study at a crop site in Iowa in the United States demonstrated that the traditional corn-soybean (CS) rotation could still accumulate SOC over this century (from 4.2 to 6.8 kg C/m2) under the current condition; whereas the continuous-corn (CC) system might have a higher SOC sequestration potential than CS. In either case, however, residue removal could reduce the sink potential substantially. Long-term simulation results also suggested that the equilibrium SOC level may vary greatly (˜5.7 to ˜11 kg C/m2) depending on cropping systems and management practices, and projected growth enhancement could make the magnitudes higher (˜7.8 to ˜13 kg C/m2). Importantly, the factorial design analysis indicated that residue management had the most significant impact (contributing 49.4%) on SOC changes, followed by CO2 Enrichment (37%), Tillage (6.2%), the combination of CO2 Enrichment-Residue removal (5.8%), and Fertilization (1.6%). In brief, this study is valuable for understanding the major forces driving SOC dynamics of agroecosystems and informative for decision-makers when seeking the enhancement of SOC sequestration potential and sustainability of biofuel production, especially in the Corn Belt region of the United States.

  2. Driving forces for home-based reablement; a qualitative study of older adults' experiences.

    Science.gov (United States)

    Hjelle, Kari Margrete; Tuntland, Hanne; Førland, Oddvar; Alvsvåg, Herdis

    2017-09-01

    As a result of the ageing population worldwide, there has been a growing international interest in a new intervention termed 'reablement'. Reablement is an early and time-limited home-based intervention with emphasis on intensive, goal-oriented and interdisciplinary rehabilitation for older adults in need of rehabilitation or at risk of functional decline. The aim of this qualitative study was to describe how older adults experienced participation in reablement. Eight older adults participated in semi-structured interviews. A qualitative content analysis was used as the analysis strategy. Four main themes emerged from the participants' experiences of participating in reablement: 'My willpower is needed', 'Being with my stuff and my people', 'The home-trainers are essential', and 'Training is physical exercises, not everyday activities'. The first three themes in particular reflected the participants' driving forces in the reablement process. Driving forces are intrinsic motivation in interaction with extrinsic motivation. Intrinsic motivation was based on the person's willpower and responsibility, and extrinsic motivation was expressed to be strengthened by being in one's home environment with 'own' people, as well as by the co-operation with the reablement team. The reablement team encouraged and supported the older adults to regain confidence in performing everyday activities as well as participating in the society. Our findings have practical significance for politicians, healthcare providers and healthcare professionals by contributing to an understanding of how intrinsic and extrinsic motivation influence reablement. Some persons need apparently more extrinsic motivational support also after the time-limited reablement period is completed. The municipal health and care services need to consider individualised follow-up programmes after the intensive reablement period in order to maintain the achieved skills to perform everyday activities and participate in

  3. Comparative Study on the Human Driving Force of Cultivated Land and Construction Land Use Change in Hubei Province,China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Change trend of cultivated land and construction land in Hubei Province is analyzed.The years 1998-2003 are the reduction period of cultivated land;the years 2004-2007 are the increase period of cultivated land;the years 1988-2002 are the slow growth period of construction land;and the years of 2003 and 2007 are the increase period of construction land.Based on related social economic statistical data in 1988-2007,human driving forces on cultivated land and construction land in Hubei Province are analyzed quantitatively and comparatively by using SPSS software and mathematical statistics method.Result shows that driving force factors have negative driving effect on cultivated land,and positive driving effect on construction land.Driving force factors have significant differences of driving effects on cultivated land and construction land.Three principal components affecting the changes of cultivated land and construction land are policy,population and economic development level,and gap between urban and rural living standards.The three principal components have different degrees of sensitivity on the two land use types and the effects direction are reverse.The other factor driving abilities are relatively weak,and these factors have relatively stronger driving force on construction land than that on cultivated land.It is put forward that Hubei Province should implement rational allocation of land resources and scientific and rational use in order to ensure land security and to realize the sustainable development of regional economy and society based on the intensive land use,the planning policy constraints,and the agricultural and industrial production.

  4. Driving forces behind the increasing cardiovascular treatment intensity.A dynamic epidemiologic model of trends in Danish cardiovascular drug utilization.

    DEFF Research Database (Denmark)

    Kildemoes, Helle Wallach; Andersen, Morten

    to 619 DDD/TID from 1996 to 2005 (117%). Population ageing accounted for 22 percentage points. Treatment intensity with statins increased from 5 to 121 DDD/TID. Population ageing accounted for one eighth of this increase. Increasing incidence rates was the main driving force behind the growing statin......Background: In many Western countries cardiovascular treatment intensity (DDD/1000 inhabitants/day, DDD/TID) has grown substantially during the last decades. Changed drug utilization pattern - rather than population ageing - was hypothesized to be the main driving force behind the growth....... Objectives: To investigate the driving forces behind the increasing treatment prevalence of cardiovascular drugs, in particular statins, by means of a dynamic epidemiologic drug utilization model. Methods: Material: All Danish residents older than 20 years by January 1, 1996 (4.0 million inhabitants), were...

  5. Geographic concentration and driving forces of agricultural land use in China

    Institute of Scientific and Technical Information of China (English)

    Yuluan ZHAO; Xiubin LI; Liangjie XIN; Haiguang HAO

    2012-01-01

    Since the 1990s,China has entered the middle phase of urbanization which leads to the existence of significant geographic concentration of agricultural land use.The average value of regional concentration degree of ten representative crops in China was 59.03%,showing a high degree of geographic concentration in farming.Some typical agriculture provinces in farming have arisen.The degree of geographic concentration in farming has been enhanced,with the average degree of regional concentration often crops increasing considerably by 3.83% in 2009compared to that in 1990 (55.20%).The spatial growing center of farming was found to move westward and northward during 1990-2009.Meanwhile food production concentrated in the Northeast China and main producing area,and cash crops production concentrated in Northwest China.Off-farm employment of rural labor force,commercialization of agricultural product and regional comparative advantage are the main driving forces of geographic concentration of agricultural land use.Governmental policies with regional differences should be considered to promote further development of agriculture.

  6. External forcing as a source for the observed multi-decadal relation between AMV and the Indian summer monsoon

    Science.gov (United States)

    Svendsen, Lea; Luo, Feifei; Sankar, Syam; Gao, Yongqi; Keenlyside, Noel; Vareed Joseph, Porathur; Johannessen, Ola

    2016-04-01

    The instrumental records show a significant positive correlation between the Atlantic multi-decadal variability (AMV) and the Indian summer monsoon (ISM) rainfall, where a positive (negative) AMV is associated with more (less) ISM rainfall. We have used both proxy reconstruction and twelve models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to investigate if the observed AMV-ISM relation is a persistent internal climate signal or externally forced. A comparison of several annual resolution proxy records both from the Atlantic and for the ISM show that the multi-decadal variability in both indices is persistent, but the link between them is not. The correlation between the two regions is weak, and even negative in some periods, before the instrumental time period. The analysis of CMIP5 simualtions is consistent with these results. While none of the CMIP5 models investigated simulate the significant AMV-ISM connection in the pre-industrial control simulations with fixed external forcing, three of the models reproduce the relation in the 20th century historical simulations with transient forcing. In these models external forcing is linked to the mid-to-upper tropospheric temperature pattern with a strengthened land-ocean contrast over South Asia, consistent with an enhanced ISM, as well as the evolution of AMV. We conclude that the significant AMV-ISM relation found in the observations after the industrial revolution may be associated with external forcing, rather than being internal climate variability.

  7. Role of external magnetic field and current closure in the force balance mechanism of a magnetically stabilized plasma torch

    Science.gov (United States)

    G, Ravi; Goyal, Vidhi

    2012-10-01

    Experimental investigations on the role of applied external magnetic field and return current closure in the force balance mechanism of a plasma torch are reported. The plasma torch is of low power and has wall, gas and magnetic stabilization mechanisms incorporated in it. Gas flow is divided into two parts: axial-central and peripheral-shroud, applied magnetic field is axial and return current is co-axial. Results indicate that application of large external magnetic field gives rise to not only J x B force but also, coupled with gas flow, to a new drag-cum-centrifugal force that acts on the plasma arc root and column. The magnetic field also plays a role in the return current closure dynamics and thus in the overall force balance mechanism. This in turn affects the electro-thermal efficiency of the plasma torch. Detailed experimental results, analytical calculations and physical model representing the processes will be presented and discussed.

  8. The Dynamic Change in the Total Arable Land and its Driving Forces in Tongling City of Anhui Province

    Institute of Scientific and Technical Information of China (English)

    Yan; LI; Zhongxiang; YU

    2014-01-01

    According to Anhui Statistical Yearbook( 2003-2012) and the second national land survey data,this article analyzes the current situation of land use and the dynamic change in the total arable land in Tongling City. On the basis of this,using grey relational analysis,this article analyzes the driving forces for arable land changes in Tongling City. Studies show that population growth,the improvement of level of urbanization and the rapid development of the economy are the main driving forces for arable land changes. Based on the findings,the strategies are put forth in order to ensure the dynamic balance of total arable land.

  9. 旅游流驱动力系统分析%Study on the driving force of tourist flows

    Institute of Scientific and Technical Information of China (English)

    杨兴柱; 顾朝林; 王群

    2011-01-01

    to spatial distance factor and ignore spatial structures of tourism origin and destination; attach importance to tourism demand factors and ignore tourism product supply.Based on the conclusion and reference of domestic and abroad relevant theory of tourist flow, pull, push, resistance, inertia and spatial structure forces are the main driving factors. Pull, push, inertia and spatial structure forces have positive correlation with tourist flows. Resistance force has negative correlation with tourist flows. Finally, the paper builds conceptual model of tourist flow-driven mechanism. A conceptual model can reflect the formation of tourist flow driven by tourism activities in both internal and external systems, consisting of tourism demand and tourism attraction. At the same time, the formation of tourist flow is affected by resistance and spatial structure. A conceptual model can also reflect a comprehensive, holistic, dynamic development and change. The conceptual model offers a new study viewpoint of tourism geography. It also provides a simple analytical framework for tourism planning, tourism marketing and management. The model can guide spatial development and travel routes organization, and infrastructure and transportation planning and also provide a scientific foundation for the harmonious and sustainable development of tourism destination as well as the implementation of tourism policy.

  10. A statistical modelling study of the abrupt millennial-scale climate changes focusing on the influence of external forcings

    CERN Document Server

    Mitsui, Takahito

    2015-01-01

    Dansgaard-Oeschger (DO) events are abrupt millennial-scale climate changes mainly detected in the North Atlantic region during the last glacial cycle. The frequency of the DO events varied in time, supposedly because of changes in background climate conditions. Here, we investigate the influences of external forcings on DO events with statistical modelling. We assume two types of generic stochastic dynamical systems models (double-well potential-type and oscillator-type), forced by the northern hemisphere summer insolation change and/or the global ice volume change. The models are calibrated by maximizing their likelihood and compared using the Bayesian Information Criterion (BIC). Among the models, the stochastic oscillator model forced by both insolation and ice volume changes is favored by the NGRIP calcium ion data. The BIC scores provide positive evidence for the ice volume forcing in the presence of the insolation forcing but weak evidence for the insolation forcing in the presence of the ice volume for...

  11. Heterogeneous Memorized Continuous Time Random Walks in an External Force Fields

    Science.gov (United States)

    Wang, Jun; Zhou, Ji; Lv, Long-Jin; Qiu, Wei-Yuan; Ren, Fu-Yao

    2014-09-01

    In this paper, we study the anomalous diffusion of a particle in an external force field whose motion is governed by nonrenewal continuous time random walks with correlated memorized waiting times, which involves Reimann-Liouville fractional derivative or Reimann-Liouville fractional integral. We show that the mean squared displacement of the test particle which is dependent on its location of the form (El-Wakil and Zahran, Chaos Solitons Fractals, 12, 1929-1935, 2001) where is the anomalous exponent, the diffusion exponent is dependent on the model parameters. We obtain the Fokker-Planck-type dynamic equations, and their stationary solutions are of the Boltzmann-Gibbs form. These processes obey a generalized Einstein-Stokes-Smoluchowski relation and the second Einstein relation. We observe that the asymptotic behavior of waiting times and subordinations are of stretched Gaussian distributions. We also discuss the time averaged in the case of an harmonic potential, and show that the process exhibits aging and ergodicity breaking.

  12. Long-term dynamics in land resource use and the driving forces in the Beressa watershed, highlands of Ethiopia

    NARCIS (Netherlands)

    Amsalu Taye, A.; Stroosnijder, L.; Graaff, de J.

    2007-01-01

    Land degradation in the Ethiopian highlands is considered to be one of the major problems threatening agricultural development and food security in the country. However, knowledge about the forces driving the long-term dynamics in land resources use is limited. This research integrates biophysical i

  13. FOREST LANDSCAPE PATTERN DYNAMICS OF LUONING COUNTY IN HENAN PROVINCE AND ITS DRIVING FORCES

    Institute of Scientific and Technical Information of China (English)

    DING Sheng-yan; QIAN Le-xiang; CAO Xin-xiang; LI Shuang; LI Hao-min

    2003-01-01

    With the help of ARC/INFOR and ERDAS software, based on the information from forest resources distribution maps and TM images, four indices were chosen to analyze spatial pattern changes of forest landscape of Luoning County, Henan Province from 1983 to 1999. The results showed that: 1) The number and total area of patches were rapidly increased with time changes. The fragmentation degree of the landscape was increasing great-ly. 2) The area of some forest patch types, especially shrub forest, economic forest, Populus spp. Forest, Quercus spp. Forest, sparse forest, deserted grassland etc. Had been greatly changed. 3) The fragemation degree of each forest patch type became greater from 1983 to 1999.4) The transition probabilities of deserted forest, economic forest,Pi-nus tabulaeformis forest, Populus spp. Forest exceed 85%,Robinia pseuoacacia forest, deserted grassland, 65% and Quercus spp. Forest, non-forest, shrub forest had smaller ones, which were 26.5%, 29.1% and 45.3%, respec-tively. The main transition trends of various patches were non-forest and Quercus spp. Forest. During the course of transition, the types that 50% of area was remained were Quercus spp. Forest, non-forest and shrub forest. Accord-ing to above analyses, the main driving forces, such as the management policies, market economy factors and influ-ences of human activities etc. Were brought out.

  14. Driving forces of organic carbon spatial distribution in the tropical seascape

    Science.gov (United States)

    Gillis, L. G.; Belshe, F. E.; Ziegler, A. D.; Bouma, T. J.

    2017-02-01

    An important ecosystem service of tropical coastal vegetation including seagrass beds and mangrove forests is their ability to accumulate carbon. Here we attempt to establish the driving forces for the accumulation of surface organic carbon in southern Thailand coastal systems. Across 12 sites we found that in line with expectations, seagrass beds (0.6 ± 0.09%) and mangrove forests (0.9 ± 0.3%) had higher organic carbon in the surface (top 5 cm) sediment than un-vegetated mudflats (0.4 ± 0.04%). Unexpectedly, however, mangrove forests in this region retained organic carbon, rather than outwell it, under normal tidal conditions. No relationship was found between organic carbon and substrate grain size. The most interesting finding of our study was that climax and pioneer seagrass species retained more carbon than mixed-species meadows, suggesting that plant morphology and meadow characteristics can be important factors in organic carbon accumulation. Insights such as these are important in developing carbon management strategies involving coastal ecosystems such as offsetting of carbon emissions. The ability of tropical coastal vegetation to sequester carbon is an important aspect for valuing the ecosystems. Our results provide some initial insight into the factors affecting carbon sequestration in these ecosystems, but also highlight the need for further research on a global scale.

  15. Stress-triggered atavistic reprogramming (STAR) addiction: driving force behind head and neck cancer?

    Science.gov (United States)

    Masuda, Muneyuki; Wakasaki, Takahiro; Toh, Satoshi

    2016-01-01

    Recent results of the Cancer Genome Atlas on head and neck squamous cell carcinoma (HNSCC) revealed that HNSCC lacked predominant gain-of-function mutations in oncogenes, whereas an essential role for epigenetics in oncogenesis has become apparent. In parallel, it has gained general acceptance that cancer is considered as complex adaptive system, which evolves responding environmental selective pressures. This somatic evolution appears to proceed concurrently with the acquisition of an atavistic pluripotent state (i.e., “stemness”), which is inducible by intrinsic epigenetic reprogramming program as demonstrated by induced pluripotent stem (iPS) cells. This Nobel prize-winning discovery has markedly accelerated and expanded cancer stem cell research from the point of epigenetic reprogramming. Taken together, we hypothesize that stress-triggered atavistic reprogramming (STAR) may be the major driving force of HNSCC evolution. In this perspective, we discuss the possible mechanisms of STAR in HNSCC, focusing on recent topics of epigenetic reprogramming in developmental and cancer cell biology. PMID:27429838

  16. Invasion of Nostocales (cyanobacteria) to Subtropical and Temperate Freshwater Lakes - Physiological, Regional, and Global Driving Forces.

    Science.gov (United States)

    Sukenik, Assaf; Hadas, Ora; Kaplan, Aaron; Quesada, Antonio

    2012-01-01

    Similar to the increased number of studies on invasive plants and animals in terrestrial and aquatic ecosystems, many reports were recently published on the invasion of Nostocales (cyanobacteria) to freshwater environments worldwide. Invasion and proliferation of Nostocales in new habitats have the potential to significantly alter the structure of the native community and to modify ecosystem functioning. But most importantly, they influence the water quality due to a variety of toxic compounds that some species produce. Therefore a special attention was given to the invasion and persistence of toxic cyanobacteria in many aquatic ecosystems. Here we summarize the currently published records on the invasion of two Nostocales genera, Cylindrospermopsis and Aphanizomenon, to lakes and water reservoirs in subtropical and temperate zones. These invading species possess traits thought to be common to many invasive organisms: high growth rate, high resource utilization efficiency and overall superior competitive abilities over native species when local conditions vary. Assuming that dispersion routes of cyanobacteria have not been changed much in recent decades, their recent establishment and proliferation in new habitats indicate changes in the environment under which they can exploit their physiological advantage over the native phytoplankton population. In many cases, global warming was identified as the major driving force for the invasion of Nostocales. Due to this uncontrollable trend, invasive Nostocales species are expected to maintain their presence in new habitats and further expand to new environments. In other cases, regional changes in nutrient loads and in biotic conditions were attributed to the invasion events.

  17. Spatial-Temporal Pattern and Driving Forces of Land Use Changes in Xiamen

    Institute of Scientific and Technical Information of China (English)

    QUAN Bin; CHEN Jian-Fei; QIU Hong-Lie; M.J.M.R(O)MKENS; YANG Xiao-Qi; JIANG Shi-Feng; LI Bi-Cheng

    2006-01-01

    Using Landsat TM data of 1988, 1998 and 2001, the dynamic process of the spatial-temporal characteristics of land use changes during 13 years from 1988 to 2001 in the special economic zone of Xiamen, China was analyzed to improve understanding and to find the driving forces of land use change so that sustainable land utilization could be practiced.During the 13 years cropland decreased remarkably by nearly 11304.95 ha. The areas of rural-urban construction and water body increased by 10152.24 ha and 848.94 ha, respectively. From 1988 to 2001, 52.5% of the lost cropland was converted into rural-urban industrial land. Rapid urbanization contributed to a great change in the rate of cropland land use during these years. Land-reclamation also contributed to a decrease in water body area as well as marine ecological and environmental destruction. In the study area 1) urbanization and industrialization, 2) infrastructure and agricultural intensification, 3) increased affluence of the farming community, and 4) policy factors have driven the land use changes.Possible sustainable land use measures included construction of a land management system, land planning, development of potential land resources, new technology applications, and marine ecological and environmental protection.

  18. Analysis of Urban Expansion and Driving Forces in Xuzhou City Based on Remote Sensing

    Institute of Scientific and Technical Information of China (English)

    HU Zhao-ling; DU Pei-jun; GUO Da-zhi

    2007-01-01

    Based on satellite remote sensing TM/ETM+ images of Xuzhou city, land use forms of the city in 1987, 1994 and 2000 were extracted by using a neural network classification method. The expansion contribution rate and annual expansion intensity index of each administrative district have been calculated and the contribution rate matrices and spatial distribution maps of land use changes were obtained. Based on the above analysis, the characteristics of urban expansion from 1987 to 2000 have been explored. From 1987 to 1994, the expansion contribution rate of Quanshan district reached 46.80%, the highest in all administrative districts of Xuzhou city; Tongshan town was in a high-speed expansion period; both Quanshan and Yunlong districts were experiencing fast-speed expansion periods while the entire city was expanding at a medium-speed with an annual expansion intensity index of 0.98; the city spread eastwards and southwards. From 1994 to 2000, the expansion contribution rate of Quanshan district reached 43.67%, the highest in Xuzhou; the entire city was in a medium-speed expansion period with an annual expansion intensity index of 1.04; the city has rapidly been extended towards the southeast. According to the contribution rate matrices of land use changes, urban expansion mainly usurps cropland and woodland. A quantitative analysis found that population growth, industrialization and economic development are the primary driving forces behind urban expansion.

  19. Driving force for indentation cracking in glass: composition, pressure and temperature dependence.

    Science.gov (United States)

    Rouxel, Tanguy

    2015-03-28

    The occurrence of damage at the surface of glass parts caused by sharp contact loading is a major issue for glass makers, suppliers and end-users. Yet, it is still a poorly understood problem from the viewpoints both of glass science and solid mechanics. Different microcracking patterns are observed at indentation sites depending on the glass composition and indentation cracks may form during both the loading and the unloading stages. Besides, we do not know much about the fracture toughness of glass and its composition dependence, so that setting a criterion for crack initiation and predicting the extent of the damage yet remain out of reach. In this study, by comparison of the behaviour of glasses from very different chemical systems and by identifying experimentally the individual contributions of the different rheological processes leading to the formation of the imprint--namely elasticity, densification and shear flow--we obtain a fairly straightforward prediction of the type and extent of the microcracks which will most likely form, depending on the physical properties of the glass. Finally, some guidelines to reduce the driving force for microcracking are proposed in the light of the effects of composition, temperature and pressure, and the areas for further research are briefly discussed.

  20. Rocky Land Desertification and its Driving Forces in the Karst Areas of Rural Guangxi, Southwest China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    With a subtropical climate, Guangxi Zhuaug Autonomous Region has a typical karst landscape. Rocky desertification has become a serious environmental issue due to its high vulnerability caused by the joint effect of natural settings and human activities, because of which its eco- environment has been deteriorated in recent years, and farmland has been disappearing sharply at the same time. This, in turn, has exacerbated the poverty level in the rural areas of the region. In this study, we monitored the spatial distribution of rocky land desertification and its temporal evolution using Landsat TM/ETM images of 1985, 1995, 2000 and 2005. We also analyzed the driving forces of the desertification and its expansion. Through constructing regression models by using all the relevant variables and considering the lagged effects as well as fixed effects, we quantified the exact role of different factors causing rocky land desertification in the study area with some new findings. The newfindings in this study are greatly helpful for preserving, restoring and reconstructing the degraded mountain environment in Guangxi and other karst areas in Southwest China, and also for alleviating poverty in the rural areas in the future.

  1. Yield Improvement and Advanced Defect Control——Driving Forces for Modeling of Bulk Crystal Growth

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Yield improvement and advanced defect control can be identified as the driving forces for modeling of industrial bulk crystal growth. Yield improvement is mainly achieved by upscaling of the whole crystal growth apparatus and increased processing windows with more tolerances for parameter variations. Advanced defect control means on one hand a reduction of the number of deficient crystal defects and on the other hand the formation of beneficial crystal defects with a uniform distribution and well defined concentrations in the whole crystal. This "defect engineering" relates to the whole crystal growth process as well as the following cooling and optional annealing processes, respectively. These topics were illustrated in the paper by examples of modeling and experimental results of bulk growth of silicon (Si), gallium arsenide (GaAs), indium phosphide (InP) and calcium fluoride (CaF2). These examples also involve the state of the art of modeling of the most important melt growth techniques, crystal pulling (Czochralski methods) and vertical gradient freeze (Bridgman-type methods).

  2. Biopolymers under large external forces and mean-field RNA virus evolutionary dynamics

    Science.gov (United States)

    Ahsan, Syed Amir

    The modeling of the mechanical response of single-molecules of DNA and RNA under large external forces through statistical mechanical methods is central to this thesis with a small portion devoted to modeling the evolutionary dynamics of positive-sense single-stranded RNA viruses. In order to develop and test models of biopolymer mechanics and illuminate the mechanisms underlying biological processes where biopolymers undergo changes in energy on the order of the thermal energy, , entails measuring forces and lengths on the scale of piconewtons (pN) and nanometers (nm), respectively. A capacity achieved in the past two decades at the single-molecule level through the development of micromanipulation techniques such as magnetic and optical tweezers, atomic force microscopy, coupled with advances in micro- and nanofabrication. The statistical mechanical models of biopolymers developed in this dissertation are dependent upon and the outcome of these advancements and resulting experiments. The dissertation begins in chapter 1 with an introduction to the structure and thermodynamics of DNA and RNA, highlighting the importance and effectiveness of simple, two-state models in their description as a prelude to the emergence of two-state models in the research manuscripts. In chapter 2 the standard models of the elasticity of polymers and of a polymer gel are reviewed, characterizing the continuum and mean-field models, including the scaling behavior of DNA in confined spaces. The research manuscript presented in the last section of chapter 2 (section 2.5), subsequent to a review of a Flory gel and in contrast to it, is a model of the elasticity of RNA as a gel, with viral RNA illustrating an instance of such a network, and shown to exhibit anomalous elastic behavior, a negative Poisson ratio, and capable of facilitating viral RNA encapsidation with further context provided in section 5.1. In chapter 3 the experimental methods and behavior of DNA and RNA under mechanical

  3. Self-consistent treatment of electrostatics in molecular DNA braiding through external forces.

    Science.gov (United States)

    Lee, Dominic J

    2014-06-01

    In this paper we consider a physical system in which two DNA molecules braid about each other. The distance between the two molecular ends, on either side of the braid, is held at a distance much larger than supercoiling radius of the braid. The system is subjected to an external pulling force, and a moment that induces the braiding. In a model, developed for understanding such a system, we assume that each molecule can be divided into a braided and unbraided section. We also suppose that the DNA is nicked so that there is no constraint of the individual linking numbers of the molecules. Included in the model are steric and electrostatic interactions, thermal fluctuations of the braided and unbraided sections of the molecule, as well as the constraint on the braid linking (catenation) number. We compare two approximations used in estimating the free energy of the braided section. One is where the amplitude of undulations of one molecule with respect to the other is determined only by steric interactions. The other is a self-consistent determination of the mean-squared amplitude of these undulations. In this second approximation electrostatics should play an important role in determining this quantity, as suggested by physical arguments. We see that if the electrostatic interaction is sufficiently large there are indeed notable differences between the two approximations. We go on to test the self-consistent approximation-included in the full model-against experimental data for such a system, and we find good agreement. However, there seems to be a slight left-right-handed braid asymmetry in some of the experimental results. We discuss what might be the origin of this small asymmetry.

  4. Gravity is indeed the driving force for fault pattern formation and westward displacement of the lithosphere

    CERN Document Server

    Papa, A R R

    2005-01-01

    Gravity influence of the Sun and the Moon on the Earth is the cause of the fault pattern on Earth's surface we observe nowadays and also of the westward displacement of the lithosphere. A somewhat related hypotheses advanced in the past have been that tidal torque of the Moon may be significant. However, it has been argued that it is untenable essentially on the grounds that the viscosity of the Earth's mantle is far too high in comparison with the forces involved. To state this it was assumed that the Earth's relevant characteristic is that of two spherical shells separated by a viscous liquid, the external shell rotating at a constant angular velocity with respect to the inner shell. Here I show that this picture is not quite right and that a more careful look leads us to one in which both shells rotates at different mean angular velocities and with a forward-backward sequence of movements relative to each other. In this way what was supposed to be the principal factor against gravity influence becomes the ...

  5. Transient Dynamics of Elastic Hele-Shaw Cell Due to External Forces with Application to Impulse Mitigation

    CERN Document Server

    Tulchinsky, Arie

    2015-01-01

    We study the transient dynamics of a viscous liquid contained in a narrow gap between a rigid surface and a parallel elastic plate. The elastic plate is deformed due to an externally applied time-varying pressure-field. We model the flow-field via the lubrication approximation, and the plate deformation by the Kirchhoff-Love plate theory. We obtain a self-similarity solution for the case of an external point force acting on the elastic plate. The pressure and deformation field during and after the application of the external force are derived and presented by closed form expressions. We examine a uniform external pressure acting on the elastic plate over a finite region and during a finite time period, similar to the viscous-elastic interaction time-scale. The interaction between elasticity and viscosity is shown to reduce by order of magnitude the pressure within the Hele-Shaw cell compared with the externally applied pressure, thus suggesting such configurations may be used for impact mitigation.

  6. Trends and projections of Southern Hemisphere baroclinicity: the role of external forcing and impact on Australian rainfall

    Science.gov (United States)

    Frederiksen, Carsten S.; Frederiksen, Jorgen S.; Sisson, Janice M.; Osbrough, Stacey L.

    2016-07-01

    Changes in the characteristics of Southern Hemisphere (SH) storms, in all seasons, during the second half of the twentieth century, have been related to changes in the annual cycle of SH baroclinic instability. In particular, significant negative trends in baroclinic instability, as measured by the Phillips Criterion, have been found in the region of the climatological storm tracks; a zonal band of significant positive trends occur further poleward. Corresponding to this decrease/increase in baroclinic instability there is a decrease/increase in the growth rate of storm formation at these latitudes over this period, and in some cases a preference for storm formation further poleward than normal. Based on model output from a multi-model ensemble (MME) of coupled atmosphere-ocean general circulation models, it is shown that these trends are the result of external radiative forcing, including anthropogenic greenhouse gases, ozone, aerosols and land-use change. The MME is used in an analysis of variance method to separate the internal (natural) variability in the Phillips Criterion from influences associated with anomalous external radiative forcing. In all seasons, the leading externally forced mode has a significant trend and a loading pattern highly correlated with the pattern of trends in the Phillips Criterion. The covariance between the externally forced component of SH rainfall and the leading external mode strongly resembles the MME pattern of SH rainfall trends. A comparison between similar analyses of MME simulations using the second half of the twenty-first century of the Representative Concentration Pathways (RCP) RCP8.5 and RCP4.5 scenarios show that trends in the Phillips Criterion and rainfall are projected to continue and intensify under increasing anthropogenic greenhouse gas concentrations.

  7. Trends and projections of Southern Hemisphere baroclinicity: the role of external forcing and impact on Australian rainfall

    Science.gov (United States)

    Frederiksen, Carsten S.; Frederiksen, Jorgen S.; Sisson, Janice M.; Osbrough, Stacey L.

    2017-05-01

    Changes in the characteristics of Southern Hemisphere (SH) storms, in all seasons, during the second half of the twentieth century, have been related to changes in the annual cycle of SH baroclinic instability. In particular, significant negative trends in baroclinic instability, as measured by the Phillips Criterion, have been found in the region of the climatological storm tracks; a zonal band of significant positive trends occur further poleward. Corresponding to this decrease/increase in baroclinic instability there is a decrease/increase in the growth rate of storm formation at these latitudes over this period, and in some cases a preference for storm formation further poleward than normal. Based on model output from a multi-model ensemble (MME) of coupled atmosphere-ocean general circulation models, it is shown that these trends are the result of external radiative forcing, including anthropogenic greenhouse gases, ozone, aerosols and land-use change. The MME is used in an analysis of variance method to separate the internal (natural) variability in the Phillips Criterion from influences associated with anomalous external radiative forcing. In all seasons, the leading externally forced mode has a significant trend and a loading pattern highly correlated with the pattern of trends in the Phillips Criterion. The covariance between the externally forced component of SH rainfall and the leading external mode strongly resembles the MME pattern of SH rainfall trends. A comparison between similar analyses of MME simulations using the second half of the twenty-first century of the Representative Concentration Pathways (RCP) RCP8.5 and RCP4.5 scenarios show that trends in the Phillips Criterion and rainfall are projected to continue and intensify under increasing anthropogenic greenhouse gas concentrations.

  8. Influence of external climate forcing on coastal upwelling systems analysed in ensemble of past millennium climate simulations

    Science.gov (United States)

    Tim, Nele; Zorita, Eduardo; Hünicke, Birgit; Yi, Xin; Emeis, Kay

    2016-04-01

    Eastern Boundary Upwelling Systems are highly productive coastal ocean areas where nutrient rich, cold water upwells by the action of favorable winds. Observations over the 20th century and ocean sediment records, which may be indicative of upwelling, display an intensification due to stronger external climate forcing, such as increasing greenhouse gas concentrations or changes in solar irradiance. This intensification is compatible with the hypothesis put forward by Bakun (1990) that a stronger external radiative forcing should lead to a more intense coastal upwelling. Here, we analyze ensemble of simulations covering the past millennium with the aim of identifying and quantifying the role of external climate forcing on upwelling in the major Eastern Boundary Upwelling System. We analyse the decadal variability and centennial trends of upwelling in ensemble of simulations with the global climate model MPI-ESM covering the past millennium, the last 150 years and the next 100 years. The future simulations were driven by three IPCC scenarios of concentrations of anthropogenic greenhouse gases, RCP2.5, RCP4.5 and RCP 8.5. For the past millennium and the last 150 years, coastal upwelling does not show any imprint of external forcing. This result indicates that chaotic internal variability has dominated upwelling intensity in major upwelling regions over the last thousand years and even since industrialisation up to present. For the 21st century, all ensemble members show a consistent and significant intensification of upwelling in the strongest scenario RCP8.5 for the Benguela upwelling region, consistent and significant weakening for Morocco and California, and no significant change for the Peruvian upwelling. Weaker scenarios do not produce consistent long-term trends that are replicated in all ensemble members. The results are confirmed by analysing another ensemble of past millennium simulations with the model CESM-CAM5 (Community Earth System Model

  9. Significance of Neglected Hydrodynamic Forces on the Motion of Submerged Particles Acted on by External Body Forces

    Science.gov (United States)

    Cooper, Daniel; Charonko, John; Vlachos, Pavlos

    2011-11-01

    Recently, the manipulation of submerged particles using electromagnetic body forces has drawn increasing interest from a variety of fields, particularly medicine, where electrophoretic manipulation in lab-on-a-chip applications and magnetic drug targeting have become important areas of interest. As a direct result of this increasing interest a large number of simulations have been performed investigating the performance of devices and systems whose operation is based upon these physics. In the vast majority of cases, these simulations are based upon a force balance of the applicable body force and Stokes drag. Such simulations neglect additional hydrodynamic forces, including the added mass, Basset, Saffman, and Magnus forces. In the current study, the full equations of motion containing all of the aforementioned terms are nondimensionalized leading to a set of nondimensional parameters governing the behavior of the particle. A parametric investigation is then performed by calculating particle trajectories for both Poiseuille and Womersley flows. This analysis reveals that in many cases, the forces neglected in previous simulations are significant and should not be neglected in future studies.

  10. Land Use Change and Driving Forces in Guangzhou City during 1996- 2012

    Institute of Scientific and Technical Information of China (English)

    Yiying; YAO; Dafang; WU; Yanyan; LIU; Yihua; LIU; Qixian; CHEN; Haolong; CHEN; Jiaxin; WU; Jialiang; ZHONG

    2015-01-01

    Based on the statistical data of land use change,from the perspective of sustainable use,we use literature inquiry,statistical analysis,GIS spatial analysis and dynamic degree model of land use,to analyze the land use change characteristics,land use amount and spatial distribution characteristics in Guangzhou City during 1996- 2012,and further elaborate the driving forces of land use change to get the basic law of land use change in Guangzhou City. The results show that the construction land was rapidly expanded,causing a significant reduction in arable land( from 129286 ha in 1996 to 84567 ha in 2012); in construction land,the land for residential,industrial and mining use and transportation land dramatically increased,and the single dynamic degree of transportation land was close to 7. 1%. In comparison with other developed cities,it is found that economic factors and policy factors are important factors affecting land use change in Guangzhou City,and the growth rate of economic density of land was high in Tianhe District and Yuexiu District. From the perspective of sustainable use,the future land use in Guangzhou City needs to better coordinate the relationship between various types of land,between socio-economic development and coordinated land use development,between environmental protection and land development and utilization. Through a series of land consolidation activities,it is necessary to strengthen the protection of farmland,improve the intensive and economical use of construction land,improve the ecological environment,and coordinate development of urban and rural areas,to ultimately achieve sustainable land use in Guangzhou City.

  11. Crop modeling: Studying the effect of water stress on the driving forces governing plant water potential

    Science.gov (United States)

    van Emmerik, T. H. M.; Mirfenderesgi, G.; Bohrer, G.; Steele-Dunne, S. C.; Van De Giesen, N.

    2015-12-01

    Water stress is one of the most important environmental factors that influence plant water dynamics. To prevent excessive water loss and physiological damage, plants can regulate transpiration by adjusting the stomatal aperture. This enhances survival, but also reduced photosynthesis and productivity. During periods of low water availability, stomatal regulation is a trade-off between optimization of either survival or production. Water stress defence mechanisms lead to significant changes in plant dynamics, e.g. leaf and stem water content. Recent research has shown that water content in a corn canopy can change up to 30% diurnally as a result of water stress, which has a considerable influence on radar backscatter from a corn canopy [1]. This highlighted the potential of water stress detection using radar. To fully explore the potential of water stress monitoring using radar, we need to understand the driving forces governing plant water potential. For this study, the recently developed the Finite-Element Tree-Crown Hydrodynamic model version 2 (FETCH2) model is applied to a corn canopy. FETCH2 is developed to resolve the hydrodynamic processes within a plant using the porous media analogy, allowing investigation of the influence of environmental stress factors on plant dynamics such as transpiration, photosynthesis, stomatal conductance, and leaf and stem water content. The model is parameterized and evaluated using a detailed dataset obtained during a three-month field experiment in Flevoland, the Netherlands, on a corn canopy. [1] van Emmerik, T., S. Steele-Dunne, J. Judge and N. van de Giesen: "Impact of Diurnal Variation in Vegetation Water Content on Radar Backscatter of Maize During Water Stress", Geosciences and Remote Sensing, IEEE Transactions on, vol. 52, issue 7, doi: 10.1109/TGRS.2014.2386142, 2015.

  12. Changes in Growing Season Vegetation and Their Associated Driving Forces in China during 2001–2012

    Directory of Open Access Journals (Sweden)

    Xianfeng Liu

    2015-11-01

    Full Text Available In recent decades, the monitoring of vegetation dynamics has become crucial because of its important role in terrestrial ecosystems. In this study, a satellite-derived normalized difference vegetation index (NDVI was combined with climate factors to explore the spatiotemporal patterns of vegetation change during the growing season, as well as their driving forces in China from 2001 to 2012. Our results showed that the growing season NDVI increased continuously during 2001–2012, with a linear trend of 1.4%/10 years (p < 0.01. The NDVI in north China mainly exhibited an increasing spatial trend, but this trend was generally decreasing in south China. The vegetation dynamics were mainly at a moderate intensity level in both the increasing and decreasing areas. The significantly increasing trend in the NDVI for arid and semi-arid areas of northwest China was attributed mainly to an increasing trend in the NDVI during the spring, whereas that for the north and northeast of China was due to an increasing trend in the NDVI during the summer and autumn. Different vegetation types exhibited great variation in their trends, where the grass-forb community had the highest linear trend of 2%/10 years (p < 0.05, followed by meadow, and needle-leaf forest with the lowest increasing trend, i.e., a linear trend of 0.3%/10 years. Our results also suggested that the cumulative precipitation during the growing season had a dominant effect on the vegetation dynamics compared with temperature for all six vegetation types. In addition, the response of different vegetation types to climate variability exhibited considerable differences. In terms of anthropological activity, our statistical analyses showed that there was a strong correlation between the cumulative afforestation area and NDVI during the study period, especially in a pilot region for ecological restoration, thereby suggesting the important role of ecological restoration programs in ecological recovery

  13. A study on the fundamental mechanism and the evolutionary driving forces behind aerobic fermentation in yeast.

    Directory of Open Access Journals (Sweden)

    Arne Hagman

    Full Text Available Baker's yeast Saccharomyces cerevisiae rapidly converts sugars to ethanol and carbon dioxide at both anaerobic and aerobic conditions. The later phenomenon is called Crabtree effect and has been described in two forms, long-term and short-term effect. We have previously studied under fully controlled aerobic conditions forty yeast species for their central carbon metabolism and the presence of long-term Crabtree effect. We have also studied ten steady-state yeast cultures, pulsed them with glucose, and followed the central carbon metabolism and the appearance of ethanol at dynamic conditions. In this paper we analyzed those wet laboratory data to elucidate possible mechanisms that determine the fate of glucose in different yeast species that cover approximately 250 million years of evolutionary history. We determine overflow metabolism to be the fundamental mechanism behind both long- and short-term Crabtree effect, which originated approximately 125-150 million years ago in the Saccharomyces lineage. The "invention" of overflow metabolism was the first step in the evolution of aerobic fermentation in yeast. It provides a general strategy to increase energy production rates, which we show is positively correlated to growth. The "invention" of overflow has also simultaneously enabled rapid glucose consumption in yeast, which is a trait that could have been selected for, to "starve" competitors in nature. We also show that glucose repression of respiration is confined mainly among S. cerevisiae and closely related species that diverged after the whole genome duplication event, less than 100 million years ago. Thus, glucose repression of respiration was apparently "invented" as a second step to further increase overflow and ethanol production, to inhibit growth of other microbes. The driving force behind the initial evolutionary steps was most likely competition with other microbes to faster consume and convert sugar into biomass, in niches that

  14. Long-term regional precipitation disparity in northwestern China and its driving forces

    Directory of Open Access Journals (Sweden)

    H. F. Lee

    2014-08-01

    Full Text Available Subject to the unique physical setting of northwestern China (NW China, precipitation in the region is characterized by salient regional differences. Yet, the long-term regional precipitation disparity in NW China still remains insufficiently-explored. In the present study, we base on historical documentation to reconstruct the precipitation indices of two macro regions in NW China between AD580–1979 to address the following issues: (1 determine the multi-decadal to centennial regional precipitation disparity in NW China, a topic which has not been systematically examined in previous paleo-climate/paleo-environment studies; and (2 find the major driving forces behind it. Wavelet analysis, which is ideal for analyzing non-stationary systems, is applied. Our results show that there is significant regional discrepancy of precipitation change in NW China over extended period. Although there is significant association between the regional precipitation disparity in NW China and various modes of atmospheric circulation, the association is characterized by a regime shift during the transition from the Medieval Warm Period to the Little Ice Age. Most importantly, the low-frequency cycle of the El Niño–Southern Oscillation is found to be the most prominent pacemaker of regional precipitation disparity in NW China at the multi-decadal to centennial timescales. Our findings help to demonstrate which atmospheric circulation is primarily responsible for the long-term regional precipitation disparity in NW China, which may have important implications for water resource management in NW China in the near future.

  15. Jordan's First Research Reactor Project: Driving Forces, Present Status and the Way Ahead

    Energy Technology Data Exchange (ETDEWEB)

    Xoubi, Ned, E-mail: Ned@Xoubi.co [Jordan Atomic Energy Commission (JAEC), P.O.Box 70, Shafa Badran, 11934 Amman (Jordan)

    2011-07-01

    In a gigantic step towards establishing Jordan's nuclear power program, Jordan Atomic Energy Commission (JAEC) is building the first nuclear research and test reactor in the Kingdom. The new reactor will serve as the focal point for Jordan Center for Nuclear Research (JCNR), a comprehensive state of the art nuclear center not only for Jordan but for the whole region, the center will include in addition to the reactor a radioisotopes production plant, a nuclear fuel fabrication plant, a cold neutron source (CNS), a radioactive waste treatment facility, and education and training center. The JRTR reactor is the only research reactor new build worldwide in 2010, it is a 5 MW light water open pool multipurpose reactor, The reactor core is composed of 18 fuel assemblies, MTR plate type, with 19.75% enriched uranium silicide (U{sub 3}Si{sub 2}) in an aluminum matrix. It is reflected on all sides by beryllium and graphite blocks. Reactor power is upgradable to 10 MW with a maximum thermal flux of 1.45x10{sup 14} cm{sup -2}s{sup -1}. The reactor reactivity is controlled by four Hafnium Control Absorber Rods (CAR). Jordan Center for Nuclear Research is located in Ramtha city, it is owned by Jordan Atomic Energy Commission (JAEC), and is contracted to Korea Atomic Energy Research Institute (KAERI) and Daewoo E and C. The JCNR project is a 56 months EPC fixed price contract for the design engineering, construction, and commissioning the JCNR reactor, and other nuclear facilities. The project presents many challenges for both the owner and the contractor, being the first nuclear reactor for Jordan, and the first nuclear export for Korea. The driving forces, present status and the way ahead will be presented in this paper. (author)

  16. Detailed Per-residue Energetic Analysis Explains the Driving Force for Microtubule Disassembly.

    Directory of Open Access Journals (Sweden)

    Ahmed T Ayoub

    2015-06-01

    Full Text Available Microtubules are long filamentous hollow cylinders whose surfaces form lattice structures of αβ-tubulin heterodimers. They perform multiple physiological roles in eukaryotic cells and are targets for therapeutic interventions. In our study, we carried out all-atom molecular dynamics simulations for arbitrarily long microtubules that have either GDP or GTP molecules in the E-site of β-tubulin. A detailed energy balance of the MM/GBSA inter-dimer interaction energy per residue contributing to the overall lateral and longitudinal structural stability was performed. The obtained results identified the key residues and tubulin domains according to their energetic contributions. They also identified the molecular forces that drive microtubule disassembly. At the tip of the plus end of the microtubule, the uneven distribution of longitudinal interaction energies within a protofilament generates a torque that bends tubulin outwardly with respect to the cylinder's axis causing disassembly. In the presence of GTP, this torque is opposed by lateral interactions that prevent outward curling, thus stabilizing the whole microtubule. Once GTP hydrolysis reaches the tip of the microtubule (lateral cap, lateral interactions become much weaker, allowing tubulin dimers to bend outwards, causing disassembly. The role of magnesium in the process of outward curling has also been demonstrated. This study also showed that the microtubule seam is the most energetically labile inter-dimer interface and could serve as a trigger point for disassembly. Based on a detailed balance of the energetic contributions per amino acid residue in the microtubule, numerous other analyses could be performed to give additional insights into the properties of microtubule dynamic instability.

  17. Effects of Micropump Driving Parameters on Traveling Wave Driving Force%行波微泵驱动参数对驱动效果的影响

    Institute of Scientific and Technical Information of China (English)

    张冲; 魏守水; 魏长智

    2012-01-01

    提出一种新型的无阀机械微泵,它依靠微泵管道顶部铺设的压电薄膜阵列产生的超声行波来驱动微管道中的流体。根据超声行波驱动微流体的原理对微泵进行ANSYS有限元建模和CFX流固耦合计算,得到了选定模态下内边长为200μm的方形微泵管道中流体的动力黏度与微泵驱动能力的关系,以及驱动电压幅值和频率对管口流速的影响曲线。结果表明:驱动电压的幅值大小与管口流速成正比,且当驱动频率等于共振频率时驱动效果最明显;当流体动力黏度小于0.001Pa.s时微流体流速随黏度增大而线性增大,之后则缓慢减小。此外,通过CFX后处理得到了微管道中的截面流速矢量图,由矢量图可以看出,在行波驱动作用显著的部分流速分布呈现自微管顶部向下逐渐减慢的特点,而在行波驱动作用极微弱的部分则流速分布近似呈抛物线形状。%A novel type of valveless mechanical micro--pump was proposed herein. It transported the liquid depending on the driving force of traveling wave which was produced by piezoelectric films fabricated on the top surface of the channel. Using finite element software, according to the principle of ultrasonic traveling wave driving,a model was structured and solved. The relationships among the ve- locity of microfluidic and driving factors such as the dynamic viscosity of liquid, the driving voltage amplitude and frequency were obtained for the first time under condition of the selected modal of square micro--pipe with a caliber of 200μm. The results show that the voltage amplitude is propor- tional to the flow velocity and the best driving efficiency is obtained on the resonance frequency;When the dynamic viscosity is below 0. 001Pa · s, the flow velocity will increase along with the rising viscos- ity while decrease above that value. In addition, the section velocity vector diagrams have been ob- tained, which illustrate that the flow

  18. Dynamics of completely unfolded and native proteins through solid-state nanopores as a function of electric driving force.

    Science.gov (United States)

    Oukhaled, Abdelghani; Cressiot, Benjamin; Bacri, Laurent; Pastoriza-Gallego, Manuela; Betton, Jean-Michel; Bourhis, Eric; Jede, Ralf; Gierak, Jacques; Auvray, Loïc; Pelta, Juan

    2011-05-24

    We report experimentally the dynamic properties of the entry and transport of unfolded and native proteins through a solid-state nanopore as a function of applied voltage, and we discuss the experimental data obtained as compared to theory. We show an exponential increase in the event frequency of current blockades and an exponential decrease in transport times as a function of the electric driving force. The normalized current blockage ratio remains constant or decreases for folded or unfolded proteins, respectively, as a function of the transmembrane potential. The unfolded protein is stretched under the electric driving force. The dwell time of native compact proteins in the pore is almost 1 order of magnitude longer than that of unfolded proteins, and the event frequency for both protein conformations is low. We discuss the possible phenomena hindering the transport of proteins through the pores, which could explain these anomalous dynamics, in particular, electro-osmotic counterflow and protein adsorption on the nanopore wall.

  19. Sector trends and driving forces of global energy use and greenhouse gas emissions: focus in industry and buildings

    Energy Technology Data Exchange (ETDEWEB)

    Price, Lynn; Worrell, Ernst; Khrushch, Marta

    1999-09-01

    Disaggregation of sectoral energy use and greenhouse gas emissions trends reveals striking differences between sectors and regions of the world. Understanding key driving forces in the energy end-use sectors provides insights for development of projections of future greenhouse gas emissions. This report examines global and regional historical trends in energy use and carbon emissions in the industrial, buildings, transport, and agriculture sectors, with a more detailed focus on industry and buildings. Activity and economic drivers as well as trends in energy and carbon intensity are evaluated. The authors show that macro-economic indicators, such as GDP, are insufficient for comprehending trends and driving forces at the sectoral level. These indicators need to be supplemented with sector-specific information for a more complete understanding of future energy use and greenhouse gas emissions.

  20. Examining Land Use and Land Cover Spatiotemporal Change and Driving Forces in Beijing from 1978 to 2010

    Directory of Open Access Journals (Sweden)

    Yichen Tian

    2014-11-01

    Full Text Available Land use and land cover (LULC datasets for Beijing in 1978, 1987, 1992, 2000 and 2010 were developed from Landsat images using the object-oriented classification approach. The relationships between social-economic, demographic and political factors and time-series LULC data were examined for the periods between 1978 and 2010. The results showed the effectiveness of using the object-oriented decision tree classification method for LULC classification with time series of Landsat images. Combined with anthropogenic driving forces, our research can effectively explain the detailed LULC change trajectories corresponding to different stages and give new insights for Beijing LULC change patterns. The results show a significant increase in forest and built-up areas, but a decrease in arable lands, due to urbanization and reforestation. Large ecological projects result in an increase of forest areas and population, and economic conditions result in urban expansion. The anthropogenic driving forces analysis results further prove that both population increase and economic development played important roles in the expansion of built-up areas. Both the qualitative and quantitative anthropogenic driving forces analysis methods were helpful for better understanding the mechanisms of LULC change.

  1. Cultivated Land Changes and Their Driving Forces-A Satellite Remote Sensing Analysis in the Yellow River Delta, China

    Institute of Scientific and Technical Information of China (English)

    ZHAO Geng-Xing; G.LIN; J.J.FLETCHER; C.YUILL

    2004-01-01

    Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined.The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e.,an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.

  2. Critical driving force for martensitic transformation fcc (γ)→hcp(ε) in Fe-Mn-Si shape memory alloys

    Institute of Scientific and Technical Information of China (English)

    金学军; 徐祖耀; 李麟

    1999-01-01

    By the application of Chou’s new geometry model and the available data from binary Fe-Mn, Fe-Si and Mn-Si systems, as well as SGTE DATA for lattice stability parameters of three elements from Dinsdale, the Gibbs free energy as a function of temperature of the fcc(γ) and hep(ε) phases in the Fe-Mn-Si system is reevaluated. The relationship between the Neel temperature of the γ phase and concentration of constituents in mole fraction, is fitted and verified by the experimental results. The critical driving force for the martensitic transformation fcc (γ)→ hep (ε), △ GCγ→ε, defined as the free energy difference between γ and ε phases at Ms of various alloys can also be obtained with a known Ms. It is found that the driving force varies with the composition of alloys, e. g. △ GCγ→ε = - 100.99 J/mol in Fe-27.0Mn-6.0Si and △ GCγ→ε = - 122.11 J/mol in Fe-26.9Mn-3.37Si. The compositional dependence of critical driving force accorded with the expression formulated by Hsu of the

  3. Quantifying the Driving Forces of Informal Urbanization in the Western Part of the Greater Cairo Metropolitan Region

    Directory of Open Access Journals (Sweden)

    Taher Osman

    2016-06-01

    Full Text Available This paper discusses the driving forces (DFs of informal urbanization (IU in the greater Cairo metropolitan region (GCMR using the Analytic Hierarchy Process (AHP. The IU patterns in the GCMR have been extremely influenced by seven DFs: geographical characteristics, availability of life facilities, economic incentives, land demand and supply, population increase, administrative function, and development plans. This research found that these forces vary significantly in how they influence urban growth in the three study sectors, namely, the middle, north, and south areas in the western part of the GCMR. The forces with the highest influence were economic incentives in the middle sector, population increase in the north sector, and the administrative function in the south sector. Due to the lower availability of buildable land in the middle sector, the land demand and supply force had a lesser influence in this sector compared to in the north and south sectors. The development plans force had medium influence in all sectors. The geographical characteristics force had little influence in both the middle and the north sectors, but higher influence than economic incentives, availability of life facilities, and development plans in the south sector. Because of the spatial variances in life facilities organizations in the GCMR, the life facilities availability force had little effect on IU in the south sector.

  4. Study on the Characteristics and Driving Forces of Changes of the Urban Land-Use Structure in Wuhan in 1990s

    Institute of Scientific and Technical Information of China (English)

    LiuYaobin; 5ongXuefeng

    2005-01-01

    On the basis of the information entropy and equilibrium degree of urban land-use spatial structure, the paper analyzes the characteristics and rules of urban land-use spatial structure changes in Wuhan in 1990s, in which the types of land-use are shrinking and urban land-use changes are disequilibria. With PCA and GRA employed, the driving forces have also been analyzed. The driving force of city welfare and social structure, the towing force of city industrial structure transition, and the pressing force of city construction and reconstruction are main momentum factors. Moreover, the latter forces are more significant.

  5. Effect of Automobile External Flow Field on Driving Stability%汽车外流场对汽车行驶稳定性影响研究

    Institute of Scientific and Technical Information of China (English)

    潘利峰; 钱仲凯; 饶大行; 陈耀辉; 李发宗; 李传志

    2012-01-01

    汽车在高速公路上会车时,空气流场对汽车行驶稳定性有很大影响。本文利用通用流体分析软件,建立两汽车会车的有限元模型,对其外流场进行流体动力学仿真,得到两汽车会车时的侧向压力和速度,分析其外流场对汽车行驶稳定性的影响。根据仿真的结果,提出了提高汽车会车时行驶稳定性的措施,以保证汽车行驶的安全性。%The external flow field will affect the driving stability of the car when it is traveling on the expressway.The paper,employing the general fluid analysis software,builds the finite element model of meeting cars,carries out the external field fluid dynamics simulation,attains the lateral pressure and the speed of the two meeting cars and analyses the effect of the external flow field on the driving stability of the automobile.Based on the simulation results,the paper puts forward the measures to improve the stability and ensure the safety of the automobile.

  6. Driving forces of main landscape change processes from past 200 years in Central Europe - differences between old democratic and post-socialist countries

    Directory of Open Access Journals (Sweden)

    Skokanová Hana

    2016-03-01

    Full Text Available The article compares and points out differences in driving forces of four main landscape change processes that shaped post-socialist countries and old democratic countries of Central Europe during the last two centuries. Studying landscape change processes and corresponding driving forces helps in understanding patterns of present landscape and can help among others in better prediction of future landscape change trends. Here, the presented results are based on review of scientific articles published in peer-reviewed journals between 2000 and 2014. Driving forces affecting these processes were grouped into four categories. Economic forces drove mainly agricultural intensification; agricultural land abandonment and urbanisation and were pronounced especially in the second half of the 20th century and at the beginning of the 21st century. Technological driving forces affected agricultural intensification especially in the 19th century and the second half of the 20th century while cultural driving forces had the biggest impact on urbanisation at the beginning of the 21st century. Political driving forces affected agricultural intensification, urbanisation as well as agricultural land abandonment and were pronounced mainly during the second half of the 20th century in the post-socialist countries. Political forces in the form of subsidies drove agricultural extensification at the beginning of the 21st century. The drivers for the agricultural intensification as well as urbanisation seem to be similar for both old democratic and post-socialist countries. In contrast, agricultural land abandonment in the old democratic countries was driven by technological, cultural and economic driving forces while in the post-socialist countries the political driving forces were mainly responsible. Changes in systems for subsidies and changes in the agricultural commodity markets are also responsible for different frequencies and rates of extensification of

  7. The role of external forcing and Pacific trade winds in recent changes of the global climate system

    Science.gov (United States)

    Friedman, Andrew; Gastineau, Guillaume; Khodri, Myriam

    2017-04-01

    The Pacific trade winds experienced an unprecedented strengthening since the mid 1990s. Several studies have proposed that the increased Pacific trade winds were associated with the reduced rate of global mean surface temperature warming in the first decade of the 21st century, as well as far-reaching atmospheric teleconnections. We designed a set of ensemble partial coupling experiments using the IPSL-CM5A-LR coupled model that allow us to cleanly distinguish the influence of Pacific trade wind variability from that of external forcing over the past few decades. In this study, we quantify the respective impacts of these processes on surface temperature, ocean heat content, and atmospheric teleconnections. We designed two ensembles of coupled simulations using partial coupling with the IPSL-CM5A-LR model to separate the Pacific internal variability and that of external radiative forcing. We prescribe surface wind stress in the tropical Pacific (20°S to 20°N) from 1979-2014 in two ensembles of 30 members each: (1) Prescribed climatological model wind stress, which allows us to estimate the influence of external radiative forcing in the absence of variability within the Pacific Ocean. (2) Wind stress anomalies from ERA-Interim reanalysis added to the model wind stress climatology, which accounts for the effects of both external radiative forcing and the wind stress variability. We find that the observed wind stress anomalies account for the pattern of eastern tropical Pacific cooling when compared to the climatology experiment, so that it resembles the observed trends from 1992-2011. The tropical Pacific shows dominant heat uptake in the western Pacific above the 20°C isotherm, which contributed to slow the warming of tropical SST during the 2000s. The trade wind increase is associated with a strengthening of the Pacific Walker circulation, and zonal shifts in tropical rainfall. Despite tropical SST biases which affect the response of tropical rainfall and the

  8. Taking Advantage of External Funding for Air Force Officer PH.D. Candidates at Civilian Universities

    Science.gov (United States)

    2009-12-01

    Education,” http://www.afit.edu/grad.cfm. 21 Clarence W. Hannon et al., “Graduate Education within the Armed Forces,” Group Research Project...Force Line Officers, Research Report no. AFHRL-TR-70-7 (Lackland AFB, TX: Personnel Research Division, 1970). 56 Clarence W. Hannon et al...Bolton, Benjamin F. Findley, William S. Mosley, Lawrence Mwambola, Jeffrey N. Renehan, Glenward L. Spivey, John F. Thompson , Jack Weinstein. ―Air

  9. Decoupled external forces in a predictor-corrector segmentation scheme for LV contours in Tagged MR images.

    Science.gov (United States)

    Garcia-Barnes, Jaume; Andaluz, Albert; Carreras, Francesc; Gil, Debora

    2010-01-01

    Computation of functional regional scores requires proper identification of LV contours. On one hand, manual segmentation is robust, but it is time consuming and requires high expertise. On the other hand, the tag pattern in TMR sequences is a problem for automatic segmentation of LV boundaries. We propose a segmentation method based on a predictor-corrector (Active Contours - Shape Models) scheme. Special stress is put in the definition of the AC external forces. First, we introduce a semantic description of the LV that discriminates myocardial tissue by using texture and motion descriptors. Second, in order to ensure convergence regardless of the initial contour, the external energy is decoupled according to the orientation of the edges in the image potential. We have validated the model in terms of error in segmented contours and accuracy of regional clinical scores.

  10. Understanding the driving forces behind the losses of soil carbon across England and Wales

    Science.gov (United States)

    Bellamy, Patricia

    2010-05-01

    More than twice as much carbon is held in soils as in vegetation or the atmosphere, and changes in soil carbon content can have a large effect on the global carbon budget. The possibility that climate change is being reinforced by increased carbon dioxide emissions from soils owing to rising temperature is the subject of a continuing debate. But evidence for the suggested feedback mechanism has to date come solely from small-scale laboratory and field experiments and modelling studies. Here we use data from the National Soil Inventory of England and Wales obtained between 1978 and 2003 to show that carbon was lost from soils across England and Wales over the survey period at a mean rate of 0.6% yr-1 (relative to the existing soil carbon content). We find that the relative rate of carbon loss increased with soil carbon content and was more than 2% yr-1 in soils with carbon contents greater than 100 g kg-1. The relationship between rate of carbon loss and carbon content is irrespective of land use, suggesting a link to climate change. Our findings indicate that losses of soil carbon in England and Wales—and by inference in other temperate regions—are likely to have been offsetting absorption of carbon by terrestrial sinks. To investigate the possible driving forces of the measured losses of soil carbon we applied a simple model of soil carbon turnover to evaluate alternative explanations for the observed trends. We find that neither changes in decomposition resulting from the effects of climate change on soil temperature and moisture, nor changes in carbon input from vegetation, could account on their own for the overall trends. Of other explanations, results indicate that past changes in land use and management were probably dominant. The climate change signal, such as it is, is masked by these other changes. A more sophisticated model of carbon change (DAYCENT) has now been applied across the whole range of soils in England and Wales. This model has been

  11. Forcing a unitary transformation by an external field comparing two approaches based on optimal control theory

    CERN Document Server

    Palao, J P; Palao, Jose P.; Kosloff, Ronnie

    2002-01-01

    A quantum gate is realized by specific unitary transformations operating on states representing qubits. Considering a quantum system employed as an element in a quantum computing scheme, the task is therefore to enforce the pre-specified unitary transformation. This task is carried out by an external time dependent field. Optimal control theory has been suggested as a method to compute the external field which alters the evolution of the system such that it performs the desire unitary transformation. This study compares two recent implementations of optimal control theory to find the field that induces a quantum gate. The first approach is based on the equation of motion of the unitary transformation. The second approach generalizes the state to state formulation of optimal control theory. This work highlight the formal relation between the two approaches.

  12. Structures of Equatorial Envelope Rossby Wave Under a Generalized External Forcing

    Institute of Scientific and Technical Information of China (English)

    FUZun-Tao; LIUShi-Da; LIUShi-Kuo

    2004-01-01

    The cubic nonlinear Schroedinger (NLS for short) equation with a generalized external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial cnvelope Rossby waves are obtained with the help of a new transformation, Jacobi elliptic functions,and elliptic equation. It is shown that different types of resonant phase-locked diabatic heating play different roles in structures of equatorial envelope Rossby wave.

  13. Structures of Equatorial Envelope Rossby Wave Under a Generalized External Forcing

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Da; LIU Shi-Kuo

    2004-01-01

    The cubic nonlinear Schrodinger (NLS for short) equation with a generalized external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial envelope Rossby waves are obtained with the help of a new transformation, Jacobi elliptic functions,and elliptic equation. It is shown that different types of resonant phase-locked diabatic heating play different roles in structures of equatorial envelope Rossby wave.

  14. Self-Biased-SMA Drive PU Microgripper with Force Sensing in Visual Servo

    Directory of Open Access Journals (Sweden)

    Ren-Jung Chang

    2013-06-01

    Full Text Available An innovative design of a polyurethane microgripper system with force sensor is developed for the measurement of gripping force in vision-based control. A microgripper mechanism integrated with a force sensing arm is fabricated by an excimer laser. The microgripper is actuated by a self-biased-SMA (Shape Memory Alloy actuator. A computer-vision method through the ERES (Extended Regional Edge Statistics algorithm is employed to track the motion of gripper. The position information of the gripping point together with the deflection of the force sensing arm is utilized for sensing force. A fuzzy expert with a PI controller in a visual servo is employed to test the performance of sensing the gripping force in grasping of 38μm diameter metal rod. In the performance test, the microgripper system provides a maximum gripping size of 40μm, a maximum force resolution of 1μN and a maximum gripping force of 58μN.

  15. Final Environmental Assessment for New Golf Driving Range at Buckley Air Force Base, Colorado

    Science.gov (United States)

    2002-11-01

    include plains cottonwood, Russian olive ( Elaeagnus angustifolia ), Virginia Environmental Assessment New Golf Driving Range Affected Environment...Chenopodium album Lamb’s quarter Chondrosum gracile Blue grama Convolvulus arvensis Bindweed Cynoglossum officinale Hound’s tongue Elaeagnus ... angustifolia Russian olive Lygodesmia juncea Skeleton Plant Opuntia mercerize Prickly pear Pathenocissus quinquifolia Virginia creeper Plantago major

  16. Driving forces analysis of reservoir wetland evolution in Beijing during 1984-2010

    Institute of Scientific and Technical Information of China (English)

    GONG Zhaoning; LI Hong; ZHAO Wenji; GONG Huili

    2013-01-01

    The reservoir wetland,which is the largest artificial wetland in Beijing,constitutes one of the important urban ecological infrastructures.Considering two elements of natural environment and socio-economy,this paper established the driving factor indexing system of Beijing reservoir wetland evolution.Natural environment driving factors include precipitation,temperature,entry water and groundwater depth; social economic driving factors include resident population,urbanization rate and per capita GDP.Using multi-temporal Landsat TM images from 1984 to 2010 in Beijing,the spatial extent and the distribution of Beijing reservoir wetlands were extracted,and the change of the wetland area about the three decade years were analyzed.Logistic regression model was used to explore for each of the three periods:from 1984 to 1998,from 1998 to 2004 and from 2004 to 2010.The results showed that the leading driving factors and their influences on reservoir wetland evolution were different for each period.During 1984-1998,two natural environment indices:average annual precipitation and entry water index were the major factors driving the increase in wetland area with the contribution rate of Logistic regression being 5.78 and 3.50,respectively,and caused the wetland growth from total area of 104.93 km2 to 219.96 km2.From 1998 to 2004,as the impact of human activities intensified the main driving factors were the number of residents,groundwater depth and urbanization rate with the contribution rate of Logistic regression 9.41,9.18,and 7.77,respectively,and caused the wetland shrinkage rapidly from the total area of 219.96 km2 to 95.71 km2.During 2004-2010,reservoir wetland evolution was impacted by both natural and socio-economic factors,and the dominant driving factors were urbanization rate and precipitation with the contribution rate of 6.62 and 4.22,respectively,and caused the wetland total area growth slightly to 109.73 km2.

  17. Spatial driving forces of dominant land use/land cover transformations in the Dongjiang River watershed, Southern China.

    Science.gov (United States)

    Gao, Changjun; Zhou, Ping; Jia, Peng; Liu, Zhiyong; Wei, Long; Tian, Huiling

    2016-02-01

    Information about changes in, and causes of, land use/land cover (LULC) is crucial for land use resource planning. We investigated the processes involved in LULC change (LUCC) in the Dongjiang Watershed, in Southern China, over a 15-year period to gain a better understanding of the causes of the main types of LUCC. Using a depth transition matrix and redundancy analysis (RDA), the major types and causes of LUCC for each LULC type over the past 15 years were identified. LUCC exhibited obvious net change, relatively low persistence, and high swap change. The swap changes in most LULC types were considered as a strong signal of LULC transformations. The driving forces behind swap changes were quantified and identified through RDA. The results showed that all driving forces played important roles in explaining swap changes of LULC, although the relative effects of these drivers varied widely with both LULC type and time period. Swap changes of the LULC types were generally classified into two categories. Some, e.g., built-up land and wetland, were affected mostly by landform and/or distance factors, while others, e.g., grassland and woodland, were modulated mostly by climate and/or socioeconomic factors. Selected spatial driving forces and local land use policies played important roles in explaining the dominant LUCC types, but on different timescales. These findings may improve understanding of the detailed processes involved in LUCC, landscape transformation, and the causes of LUCC in other areas with extensive LUCC and could help managers plan, design, and implement land resource management.

  18. Numerical-analytical investigation into impact pipe driving in soil with dry friction. Part I: Nondeformable external medium

    CERN Document Server

    Aleksandrova, Nadezhda

    2013-01-01

    The study focuses on propagation of longitudinal waves in an elastic pipe partly embedded in a medium with dry friction. Mathematical formulation of the problem on the impact pipe driving into the soil is based on the model of longitudinal vibration of an elastic rod with taking into account lateral resistance. The lateral resistance of soil is described by the law of the contact dry friction. Numerical and analytical solutions to problems on longitudinal impulse loading of a pipe are compared.

  19. Euler-Poincaré Reduction of Externally Forced Rigid Body Motion

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    2004-01-01

    . Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincaré reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modelling, estimation and control of mechanical systems......-known Euler-Poincaré reduction to a rigid body motion with forcing....

  20. Calculation of the self-formation driving force for composite microstructure in liquid immiscible alloy system

    Institute of Scientific and Technical Information of China (English)

    LIU Xingjun; WANG Cuiping; Ikuo OHNUMA; Ryosuke KAINUMA; Kiyohito ISHIDA; CHEN Xiaohu

    2005-01-01

    Using Becker's method, we calculate the interfacial energy between two liquid phases in an immiscible system. Based on the Gibbs-Thomson equation, the force acting on the droplet towards the thermal center can be obtained by integrating the interfacial energy between the droplet and matrix liquid phase, which is related to both the radius of a droplet and the temperature gradient. In addition, the forces of gravitation and buoyancy also act on the droplet. The calculated results indicate that the resultant for these forces together mainly decides the microstructure morphology of the solidified alloy. The calculated results are in good agreement with the corresponding experimental results.

  1. Trade in Service:A New Driving Force for World Economic Recovery

    Institute of Scientific and Technical Information of China (English)

    Yan Manman

    2009-01-01

    @@ Energy scarcity,environmental pressure and sluggish external demand,all are testing the development strategy of counties worldwide in the post-crisis era.On November 24,the 2nd China Trade in Services Congress pulled its curtains at the China National Convention Center in Beijing.

  2. The Economic Rationality and Institutional Driving Force of Edible Agro-products Enterprises Adopting ISO9000 Standards

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhi-jing; WU Xiu-min; CHEN Hong-yue

    2011-01-01

    This paper analyzed the economic rationality and institutional driving force of edible agro-products enterprises adopting ISO9000 standards,and built the theoretical analysis framework of enterprises adopting ISO9000 standards.The results indicated that the enterprises adopted ISO9000 standards form a variety of promoting product quality and safety business strategy options based on the considerations that getting economic efficiency and the access to resources.Based on the results,some recommendations were given for stimulating enterprises to adopt ISO9000 standards.

  3. Electrochemical reduction of carbon fluorine bond in 4-fluorobenzonitrile Mechanistic analysis employing Marcus Hush quadratic activation-driving force relation

    Science.gov (United States)

    Muthukrishnan, A.; Sangaranarayanan, M. V.

    2007-10-01

    The reduction of carbon-fluorine bond in 4-fluorobenzonitrile in acetonitrile as the solvent, is analyzed using convolution potential sweep voltammetry and the dependence of the transfer coefficient on potential is investigated within the framework of Marcus-Hush quadratic activation-driving force theory. The validity of stepwise mechanism is inferred from solvent reorganization energy estimates as well as bond length calculations using B3LYP/6-31g(d) method. A novel method of estimating the standard reduction potential of the 4-fluorobenzonitrile in acetonitrile is proposed.

  4. Motion of essentially admissible V-shaped polygonal curves govorned by generalized crystalline motion with a driving force

    OpenAIRE

    ISHIWATA, Tetsuya

    2012-01-01

    In this paper we consider the motion of non-closed planar polygonal curves governed by generalized crystalline curvature flow with a driving force. In the context of ”crystalline motion”, we usually restrict the curves in the special class of polygonal curves, so-called ”admissible class.” We here extend the previous results to wider class which is called ”essentially admissible class.” In such a class, there are no order-preserving structure, thus, controlling the movement of the solution cu...

  5. Effect of Lanthanum on Driving Force for Cu6Sn5 Growth and Improvement of Solder Joint Reliability

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By means of adding low content of rare earth element La into Sn60-Pb40 solder alloy, the growth of Cu6Sn5 intermetallic compound at the interface of solder joint is hindered, and the thermal fatigue life of solder joint is increased by 2 times. The results of thermodynamic calculation based on diffusion kinetics show that, the driving force for Cu6Sn5 growth is lowered by adding small content of La in Sn60-Pb40 solder alloy. Meanwhile, there is an effective local mole fraction range of La, in which, 0.18% is the limited value and 0.08% is the best value.

  6. Protein folding: complex potential for the driving force in a two-dimensional space of collective variables.

    Science.gov (United States)

    Chekmarev, Sergei F

    2013-10-14

    Using the Helmholtz decomposition of the vector field of folding fluxes in a two-dimensional space of collective variables, a potential of the driving force for protein folding is introduced. The potential has two components. One component is responsible for the source and sink of the folding flows, which represent respectively, the unfolded states and the native state of the protein, and the other, which accounts for the flow vorticity inherently generated at the periphery of the flow field, is responsible for the canalization of the flow between the source and sink. The theoretical consideration is illustrated by calculations for a model β-hairpin protein.

  7. Late Pliocene to Pleistocene sensitivity of the Greenland Ice Sheet in response to external forcing and internal feedbacks

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Sebastian J.; DeConto, Robert M. [University of Massachusetts, Department of Geosciences, Amherst, MA (United States); Pollard, David [Pennsylvania State University, Earth and Environmental Systems Institute, College of Earth and Mineral Sciences, University Park, PA (United States)

    2011-09-15

    The timing and nature of ice sheet variations on Greenland over the last {proportional_to}5 million years remain largely uncertain. Here, we use a coupled climate-vegetation-ice sheet model to determine the climatic sensitivity of Greenland to combined sets of external forcings and internal feedbacks operating on glacial-interglacial timescales. In particular, we assess the role of atmospheric pCO{sub 2}, orbital forcing, and vegetation dynamics in modifying thresholds for the onset of glaciation in late Pliocene and Pleistocene. The response of circum-Arctic vegetation to declining levels of pCO{sub 2} (from 400 to 200 ppmv) and decreasing summer insolation includes a shift from boreal forest to tundra biomes, with implications for the surface energy balance. The expansion of tundra amplifies summer surface cooling and heat loss from the ground, leading to an expanded summer snow cover over Greenland. Atmospheric and land surface fields respond to forcing most prominently in late spring-summer and are more sensitive at lower Pleistocene-like levels of pCO{sub 2}. We find cold boreal summer orbits produce favorable conditions for ice sheet growth, however simulated ice sheet extents are highly dependent on both background pCO{sub 2} levels and land-surface characteristics. As a result, late Pliocene ice sheet configurations on Greenland differ considerably from late Pleistocene, with smaller ice caps on high elevations of southern and eastern Greenland, even when orbital forcing is favorable for ice sheet growth. (orig.)

  8. Multi-scales Analysis of Driving Forces on Land Use/Cover Change in China: Taking Farmland Returning to Forest or Grassland as a Case

    Institute of Scientific and Technical Information of China (English)

    Zhou Hongjian; Huang Shuling; Wang Yuanyuan; Wang Jing'ai; Jia Huicong

    2006-01-01

    Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecological security level and influences the regional sustainable development. Adjusting unreasonable land use mode and reconstructing natural land cover are important ways to maintain and improve the ecological environment. Also reclaiming farmland as areas for forests and grasslands (FRFG) is another way. Successful implementation of FRFG in China is the result of comprehensive effect of the multi-scales driving forces.This paper analyses the driving forces of FRFG in China on a national (country) -regional (province) - local(county) - household (farmer) level scale, and the results are: driving forces at the national scale include ecological and food security and the western development of China;at the regional scale, ecological and economic benefits become the main factors to influence the dimension of FRFG under the same policy. The driving forces can be divided into 6 types: industrial structure adjustment,water source protection, flood prevention, the Three-Gorge Project protection, reduction of the amount of sediment flowing into the Yellow River and wind erosion desertification prevention. The driving forces at the local scale can be divided into 12 types with developing leading industries, increasing farmers'income and improving agricultural production conditions as the main types; at the household scale, the national policy meeting farmers' demands and the optimization of individual interests are all driving forces.

  9. Predation risk as a driving force for phenotypic assortment: a cross-population comparison.

    Science.gov (United States)

    Croft, D P; Darden, S K; Ruxton, G D

    2009-05-22

    Frequency-dependent predation has been proposed as a general mechanism driving the phenotypic assortment of social groups via the 'oddity effect', which occurs when the presence of odd individuals in a group allows a predator to fixate on a single prey item, increasing the predator's attack-to-kill ratio. However, the generality of the oddity effect has been debated and, previously, there has not been an ecological assessment of the role of predation risk in driving the phenotypic assortment of social groups. Here, we compare the levels of body length assortment of social groups between populations of the Trinidadian guppy (Poecilia reticulata) that experience differences in predation risk. As predicted by the oddity effect hypothesis, we observe phenotypic assortment by body length to be greater under high predation risk. However, we found that a number of low-predation populations were also significantly assorted by body length, suggesting that other mechanisms may have a role to play.

  10. Quasi-two-layer finite-volume scheme for modeling shallow water flows with the presence of external forces

    CERN Document Server

    Karelsky, K V; Slavin, A G

    2011-01-01

    The numerical method for study of hydrodynamic flows over an arbitrary bed profile in the presence of external force is proposed in this paper. This method takes into account the external force effect, it uses the quasi-two-layer model of hydrodynamic flows over a stepwise boundary with consideration of features of the flow near the step. A distinctive feature of the proposed method is the consideration of the properties of the process of the waterfall, namely the fluid flow on the step in which the fluid does not wet part of the vertical wall of the step. The presence of dry zones in the vertical part of the step indicates violation of the conditions of hydrostatic flow. The quasi-two-layer approach allows to determine the size of the dry zone of the vertical component of the step. Consequently it gives an opportunity to figure out the amount of kinetic energy dissipation. There are performed the numerical simulations based on the proposed algorithm of various physical phenomena, such as a breakdown of the r...

  11. Improvements in springback control by external force laser-assisted sheet bending of titanium and aluminum alloys

    Science.gov (United States)

    Gisario, A.; Barletta, M.; Venettacci, S.

    2016-12-01

    The present investigation deals with an external-force laser assisted bending process of Grade 2 CP titanium and AA 7075 T6 aluminum sheets. High bending angles, sharp fillet radii and control of springback were achieved by tuning the contact pressure of a hydraulically driven tool with the local and selective heating of the bending zone by irradiation with a high power diode laser. First, the role of laser operational parameters, namely power, scanning speed and number of passes, in metal bending was investigated, allowing to identify the most suitable processing window. Second, a custom-built equipment to measure the bending angle during the forming process, together with the metal temperature, was implemented. Real-time monitoring of the bending angle and temperature allowed to evaluate the continuous evolution of the geometry of the metal substrates during the external force laser-assisted bending process. Experimental results showed both metal sheets could be bent to high angles with very low fillet radii by the appropriate combination of the tooling contact pressure and selective laser heating of the bending zone. Laser heating also reduces the risk of rupture in both metals during bending at high angles, limits the springback extent up to 10 times on titanium and 30 times on aluminum in comparison with conventional bending process and does not affect significantly the visual appearance of the bending zone.

  12. Pipeline integrity management: integration of geotechnical and mechanical assessment to control potential risks due to external forces

    Energy Technology Data Exchange (ETDEWEB)

    Malpartida Moya, John E.; Sota, Giancarlo Massucco de la; Seri, Walter [Compania Operadora de Gas del Amazonas, Lima (Peru)

    2009-07-01

    Every pipeline integrity management system evaluates and controls various threats. On pipelines which have particular characteristics as it is the case of the Andean pipelines and pipelines crossing jungles, one of the main threats are the external forces. Even, this threat causes a greater number of failures than other threats like corrosion or the third part damage. Facing this situation, the pipeline integrity management system of TgP has achieved an important development in the use and suitable handling of the information provided by diverse techniques of pipeline mechanical inspection and geotechnical inspection of the right-of-way (ROW). This document presents our methodology, which interrelate information of the in-line inspection, information of geotechnical inspections of the ROW, instrumentation (Strain Gages), topographic monitoring, among others. All this information is supported in a Geographic Information System (GIS) which allows us to integrate the information. By means of the pipeline integrity management system we control potential risks due to external forces, we have been able to act before events become critical, with no occurrence of failures. This system allows us simultaneously to optimize efforts and preserve the mechanical integrity of our pipelines, not producing neither personal nor environmental nor economical affectation. (author)

  13. An Examination of the External and Internal Forces that have Shaped the Department of Veterans Affairs

    Science.gov (United States)

    2014-05-22

    vacation to the West coast.65 However, before his death, and in another of his interesting management choices , he selected a highly qualified...of the bonus.98 Congress was more forgiving and recognized the public perception of the Army’s use of force on veterans. They voted to provide a per...Hoover to head the review. Mr. Hoover, a Republican, may have seemed an unusual choice for a Democratic President, but he was a respected organizer

  14. Using LDR as Sensing Element for an External Fuzzy Controller Applied in Photovoltaic Pumping Systems with Variable-Speed Drives.

    Science.gov (United States)

    Maranhão, Geraldo Neves De A; Brito, Alaan Ubaiara; Leal, Anderson Marques; Fonseca, Jéssica Kelly Silva; Macêdo, Wilson Negrão

    2015-09-22

    In the present paper, a fuzzy controller applied to a Variable-Speed Drive (VSD) for use in Photovoltaic Pumping Systems (PVPS) is proposed. The fuzzy logic system (FLS) used is embedded in a microcontroller and corresponds to a proportional-derivative controller. A Light-Dependent Resistor (LDR) is used to measure, approximately, the irradiance incident on the PV array. Experimental tests are executed using an Arduino board. The experimental results show that the fuzzy controller is capable of operating the system continuously throughout the day and controlling the direct current (DC) voltage level in the VSD with a good performance.

  15. Using LDR as Sensing Element for an External Fuzzy Controller Applied in Photovoltaic Pumping Systems with Variable-Speed Drives

    Directory of Open Access Journals (Sweden)

    Geraldo Neves De A. Maranhão

    2015-09-01

    Full Text Available In the present paper, a fuzzy controller applied to a Variable-Speed Drive (VSD for use in Photovoltaic Pumping Systems (PVPS is proposed. The fuzzy logic system (FLS used is embedded in a microcontroller and corresponds to a proportional-derivative controller. A Light-Dependent Resistor (LDR is used to measure, approximately, the irradiance incident on the PV array. Experimental tests are executed using an Arduino board. The experimental results show that the fuzzy controller is capable of operating the system continuously throughout the day and controlling the direct current (DC voltage level in the VSD with a good performance.

  16. Bilateral deficit in explosive force production is not caused by changes in agonist neural drive.

    Directory of Open Access Journals (Sweden)

    Matthew W Buckthorpe

    Full Text Available Bilateral deficit (BLD describes the phenomenon of a reduction in performance during synchronous bilateral (BL movements when compared to the sum of identical unilateral (UL movements. Despite a large body of research investigating BLD of maximal voluntary force (MVF there exist a paucity of research examining the BLD for explosive strength. Therefore, this study investigated the BLD in voluntary and electrically-evoked explosive isometric contractions of the knee extensors and assessed agonist and antagonist neuromuscular activation and measurement artefacts as potential mechanisms. Thirteen healthy untrained males performed a series of maximum and explosive voluntary contractions bilaterally (BL and unilaterally (UL. UL and BL evoked twitch and octet contractions were also elicited. Two separate load cells were used to measure MVF and explosive force at 50, 100 and 150 ms after force onset. Surface EMG amplitude was measured from three superficial agonists and an antagonist. Rate of force development (RFD and EMG were reported over consecutive 50 ms periods (0-50, 50-100 and 100-150 ms. Performance during UL contractions was compared to combined BL performance to measure BLD. Single limb performance during the BL contractions was assessed and potential measurement artefacts, including synchronisation of force onset from the two limbs, controlled for. MVF showed no BLD (P = 0.551, but there was a BLD for explosive force at 100 ms (11.2%, P = 0.007. There was a BLD in RFD 50-100 ms (14.9%, P = 0.004, but not for the other periods. Interestingly, there was a BLD in evoked force measures (6.3-9.0%, P<0.001. There was no difference in agonist or antagonist EMG for any condition (P≥0.233. Measurement artefacts contributed minimally to the observed BLD. The BLD in volitional explosive force found here could not be explained by measurement issues, or agonist and antagonist neuromuscular activation. The BLD in voluntary and evoked explosive force

  17. Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing

    Directory of Open Access Journals (Sweden)

    E. Katragkou

    2009-05-01

    Full Text Available Regional air quality decadal simulations were carried out using the air quality model CAMx driven off-line by the regional climate model RegCM3 for the time slice 1991–2000 using two different datasets of external meteorological forcing to constrain RegCM3: the ERA40 global atmospheric reanalysis dataset and the output from the GCM ECHAM5. The focus of this work is to compare the perfect lateral boundary conditions experiment with the GCM driven control experiment and to investigate how this external meteorological forcing affects near surface ozone. The different RegCM3 meteorological forcings resulted in changes of near surface ozone over Europe ranging between ±5 ppb for winter and summer, while all model parameterizations and anthropogenic emissions remained unchanged. Changes in near surface ozone are induced by changes in meteorological fields and biogenic emissions, which are on-line calculated and meteorology-dependent. The model simulations suggest that the change in solar radiation is the factor that mostly modulates the ozone changes in summer. During winter season it is found that the induced changes in NOx explain about 40% of the ozone variability. The meteorological induced changes in biogenic emissions are quite low for winter with rather small impact on ozone while they are more temperature than radiation dependent. Using multiple regression analysis to associate the changes in near surface ozone with the respective changes in selected meteorological parameters and ozone precursors, an explained variance of 70% in summer and 60% in winter is reproduced.

  18. Increasing climate extremes under global warming - What is the driving force?

    Science.gov (United States)

    Yoon, Jin-Ho

    2017-04-01

    More climate extreme events have occurred in recent years, including the continual development of extreme drought in California, the severe cold winters in the eastern U.S. since 2014, 2015 Washington drought, and excessive wildfire events over Alaska in 2015. These have been casually attributed to global warming. However, a need for further understanding of mechanisms responsible for climate extremes is growing. In this presentation, we'll use sets of climate model simulation that designed to identify the role of the oceanic feedback in increasing climate extremes under global warming. One is with a fully coupled climate model forced by 1% ramping CO2, and the other is with an atmosphere only model forced by the same CO2 forcing. By contrasting these two, an importance of the oceanic feedback in increasing climate extremes under global warming can be diagnosed.

  19. Blood pressure is the major driving force for plaque formation in aortic-constricted ApoE-/- mice

    DEFF Research Database (Denmark)

    Johansson, Maria E.; Wickman, Anna; Skøtt, Ole

    2006-01-01

    OBJECTIVE: Using an aortic constriction model in mice, we studied whether the increase in pressure or the activation of the renin-angiotensin system (RAS) and its main receptors is the main driving force for plaque progression. METHODS: Male ApoE mice underwent sham surgery or placement of a supr......OBJECTIVE: Using an aortic constriction model in mice, we studied whether the increase in pressure or the activation of the renin-angiotensin system (RAS) and its main receptors is the main driving force for plaque progression. METHODS: Male ApoE mice underwent sham surgery or placement...... of a suprarenal silver clip around the aorta (AoC). Half the group was treated with the selective AT1 receptor antagonist losartan (30 mg/kg per day) for 4 weeks. RESULTS: Anesthetized mean arterial pressure (MAP) was increased in AoC mice compared to sham (106 +/- 3 versus 90 +/- 1 mmHg, P ....09 versus 0.07 +/- 0.01%, P distribution. Furthermore, we found no support...

  20. [Land use change dynamics and driving forces of the vulnerable ecological region in northwestern Shanxi Province, China].

    Science.gov (United States)

    Li, Xiu-Fen; Liu, Li-Min; Qi, Xin; Zhang, Jin-Xin; Zhao, Tong-Bin; Wang, Yi; Liu, Xue-Fen; Zhou, Yong-Bin

    2014-10-01

    By using remote sensing and GIS technology, this paper collected land use information of 1980, 1990, 2000 and 2010 and the relevant statistical data, and analyzed the characteristics of land use change and its driving forces in northwestern Shanxi Province, the typical ecological fragile area. The results showed that there were significant changes in land use patterns in the past 30 years. During 1980-1990, 1990-2000 and 2000-2010 periods, the area of farmland decreased continuously, while the areas of grassland and woodland experienced increase-decrease-increase and decrease-increase-decrease patterns of change, respectively. The areas of industrial and resident lands increased continuously, but the water body and unused land decreased. The farmland was mainly transformed to grassland and woodland, and the areas of industrial and resident lands increased from the farmland. The lost area of water body was transformed to grassland and farmland. The decrease of unused land was due to the implementation of ecological engineering and urban ex-panding. In general, the changes of land use types were significantly higher before 2000 than after 2000. The industrial and resident lands, unused land and grassland changed drastically. The relationships between land use types and driving forces indicated that population pressure and economic development led to the changes of industrial land and farmland; policy of forestry ecological engi- neering drove the changes of woodland and grassland; the drought-characterized climate was the major cause inducing the decrease of water area and hindering the restoration of forest.

  1. Experimental evidence of landscape reorganization under changing external forcing: implications to climate-driven knickpoints

    Science.gov (United States)

    Singh, Arvind; Tejedor, Alejandro; Grimaud, Jean-Louis; Foufoula-Georgiou, Efi

    2017-04-01

    Understanding and quantifying geomorphic and topologic re-organization of landscape in response to changing climatic or tectonic forcing is of scientific and practical interest. Although several studies have addressed the large-scale response (e.g., change in mean relief), studies on the smaller-scale drainage pattern re-organization and quantification of landscape vulnerability to the timing, magnitude, and frequency of changing forcing are lacking. To that goal, a series of controlled laboratory experiments were conducted to study the effect of changing precipitation patterns on landscape evolution at the short and long-time scales. High resolution digital elevation (DEM) both in space and time were measured for a range of rainfall patterns and uplift rates. Results from our study show a distinct signature of the precipitation increase on the probabilistic and geometrical structure of landscape features, evident in widening and deepening of channels and valleys, change in drainage patterns within sub-basins and change in the space-time structure of erosional and depositional events. A spatially explicit analysis of the locus of these erosional and depositional events show an acceleration of erosion in the hillslopes when the rainfall intensity is increased, while the incision in fluvial channels is slowed down exhibiting a sediment-flux dependent behavior. Finally, we document the changes in the longitudinal river profiles with increasing precipitation intensity, revealing the formation of knickpoints at certain confluences where large discontinuities in the ratio Qs/Qw are observed.

  2. The Effects of Dominant Driving Forces on Summer Precipitation during Different Periods in Beijing

    Directory of Open Access Journals (Sweden)

    Fuxing Li

    2017-02-01

    Full Text Available Wavelet analysis methods (CWT, XWT, WTC were employed to evaluate the impact of dominant climatic driving factors on summer precipitation in the Beijing area based on monthly precipitation data of Beijing ranging from 1880 to 2014. The two climatic driving factors, i.e., the East Asian summer monsoon (EASM and the Northern Limit of Western Pacific Subtropical High (NWPSH were considered in particular. The relationships between summer precipitation and EASM/NWPSH were also examined. The results revealed similar periods in low-frequency oscillation (76–95 years and mid-range frequency oscillation (32–60 years for the summer precipitation in the Beijing area and EASM/NWPSH. The summer precipitation correlated positively with the NWPSH and EASM, especially for periods of 43 years and 33 years, respectively. This indicates that summer precipitation during 1880–1960 and during the years after 1960 was significantly affected by NWPSH and EASM, respectively. Based on the periodic change of 33 years for both summer precipitation and EASM, heavy precipitation can be expected to occur again in Beijing at approximately 2026. Understanding the relationships between summer precipitation and climatic factors is of significant importance for precipitation predictions and water resource variations in the Beijing area.

  3. Increases in inspiratory neural drive in response to rapid oscillating airflow braking forces (vibration).

    Science.gov (United States)

    Sumners, David Paul; Green, David A; Mileva, Katya N; Bowtell, Joanna L

    2008-02-29

    To investigate whether 10 breaths against a vibration stimulus elicits increments of spontaneous and maximal inspiratory mouth pressure (maxMP) and tidal mean inspiratory flow (iV(T)/T(I)) upon stimulus removal. Twelve healthy subjects (8 female, 4 male; 22-50 years old), recruited from the University student body, completed 3 maximal inspirations before (pre) and after (post) 10 inspirations against resistive loading with a vibration-type stimulus (VIB; youbreathe, Exoscience Ltd., London, UK), pressure-matched resistive loading (RES) or resting breathing (CON; no load). The trials were presented in a random order. maxMP and involuntary tidal breathing were compared pre and post conditioning. Inspiratory neural drive increased only after VIB as evidenced by increased tidal and maxMP and mean inspiratory flow (iV(T)/T(I); p control breathing on maximal maxMP or tidal responses. Ten conditioning breaths of VIB lead to increased maximal inspiratory mouth pressure and spontaneous mouth pressure and mean inspiratory flow possibly through a common mechanism of increased descending respiratory drive.

  4. Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012

    DEFF Research Database (Denmark)

    Muresan, Ioana Stefania; Khan, Shfaqat Abbas; Aschwanden, Andy

    thickness or retreat of the floating tongue of a glacier) caused by enhanced calving or a longer-term thinning due to a mass deficit of the ice sheet. Recent findings indicate the reduced buttressing at the marine terminus is responsible for the recent dynamic changes observed in Greenland......-term trends of several decade time scales. Here, we study the mechanisms controlling dynamic changes at the terminus of Jakobshavn Isbræ over a period of 172 years. The recent glacier acceleration began in late 1990s but there is evidence for glacier retreat of comparable magnitude in 1930s, when a similarly...... warm period occurred. To control the acceleration and retreat based on observed front positions during 1840-2012, we use an ocean model modifier that implements forcing at the ocean boundary using melange back pressure offsets. The mean temperature anomaly in west Greenland, the North Atlantic...

  5. Ultrasensitive hysteretic force sensing with parametric nonlinear oscillators

    Science.gov (United States)

    Papariello, Luca; Zilberberg, Oded; Eichler, Alexander; Chitra, R.

    2016-08-01

    We propose a method for linear detection of weak forces using parametrically driven nonlinear resonators. The method is based on a peculiar feature in the response of the resonator to a near resonant periodic external force. This feature stems from a complex interplay among the parametric drive, external force, and nonlinearities. For weak parametric drive, the response exhibits the standard Duffing-like single jump hysteresis. For stronger drive amplitudes, we find a qualitatively new double jump hysteresis which arises from stable solutions generated by the cubic Duffing nonlinearity. The additional jump exists only if the external force is present and the frequency at which it occurs depends linearly on the amplitude of the external force, permitting a straightforward ultrasensitive detection of weak forces. With state-of-the-art nanomechanical resonators, our scheme should permit force detection in the attonewton range.

  6. The Study on the Block Boundary's Driving Forces and Tectonic Stress Field of China Mainland and Its Adjacent Areas Using GPS Data

    Institute of Scientific and Technical Information of China (English)

    Du Zhi-xing; Qu Ji-kun; Han Bao-min; Jin Feng-xiang; Chai Yan-ju

    2003-01-01

    After reviewing the inversion study on the driving forces of China mainland and its adjacent areas, the inversion computation is made by means of genetic finite element method and covering complex method based on the displacement observations of the Crustal Movement Observation Network of China. The whole procedures of inversion study, including parameter selection, computation conditions, inversion analysis and interpretation, are given out in details. Then some conclusions are drawn:(1)the main driving forces acting on China mainland are still from the collision of Indian plate with Eurasian plate;(2)the driving forces of Pacific plate and Philippine plate are significant to the eastern China;(3)the back basin of Japan sea arc is continuously extending;(4)the forces from north prevent the northern motion of China.

  7. Self-similar expansion of solar coronal mass ejections: Implications for Lorentz self-force driving

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, Prasad; Arunbabu, K. P.; Mauriya, Adwiteey [Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008 (India); Vourlidas, Angelos, E-mail: p.subramanian@iiserpune.ac.in [Space Science Division, Naval Research Laboratory, 4555 Overlook Avenue, SW Washington, DC 20375 (United States)

    2014-08-01

    We examine the propagation of several coronal mass ejections (CMEs) with well-observed flux rope signatures in the field of view of the SECCHI coronagraphs on board the STEREO satellites using the graduated cylindrical shell fitting method of Thernisien et al. We find that the manner in which they propagate is approximately self-similar; i.e., the ratio (κ) of the flux rope minor radius to its major radius remains approximately constant with time. We use this observation of self-similarity to draw conclusions regarding the local pitch angle (γ) of the flux rope magnetic field and the misalignment angle (χ) between the current density J and the magnetic field B. Our results suggest that the magnetic field and current configurations inside flux ropes deviate substantially from a force-free state in typical coronagraph fields of view, validating the idea of CMEs being driven by Lorentz self-forces.

  8. Both contractile axial and lateral traction force dynamics drive amoeboid cell motility.

    Science.gov (United States)

    Bastounis, Effie; Meili, Ruedi; Álvarez-González, Begoña; Francois, Joshua; del Álamo, Juan C; Firtel, Richard A; Lasheras, Juan C

    2014-03-17

    Chemotaxing Dictyostelium discoideum cells adapt their morphology and migration speed in response to intrinsic and extrinsic cues. Using Fourier traction force microscopy, we measured the spatiotemporal evolution of shape and traction stresses and constructed traction tension kymographs to analyze cell motility as a function of the dynamics of the cell's mechanically active traction adhesions. We show that wild-type cells migrate in a step-wise fashion, mainly forming stationary traction adhesions along their anterior-posterior axes and exerting strong contractile axial forces. We demonstrate that lateral forces are also important for motility, especially for migration on highly adhesive substrates. Analysis of two mutant strains lacking distinct actin cross-linkers (mhcA(-) and abp120(-) cells) on normal and highly adhesive substrates supports a key role for lateral contractions in amoeboid cell motility, whereas the differences in their traction adhesion dynamics suggest that these two strains use distinct mechanisms to achieve migration. Finally, we provide evidence that the above patterns of migration may be conserved in mammalian amoeboid cells.

  9. Line tension at lipid phase boundaries as driving force for HIV fusion peptide-mediated fusion

    Science.gov (United States)

    Yang, Sung-Tae; Kiessling, Volker; Tamm, Lukas K.

    2016-04-01

    Lipids and proteins are organized in cellular membranes in clusters, often called `lipid rafts'. Although raft-constituent ordered lipid domains are thought to be energetically unfavourable for membrane fusion, rafts have long been implicated in many biological fusion processes. For the case of HIV gp41-mediated membrane fusion, this apparent contradiction can be resolved by recognizing that the interfaces between ordered and disordered lipid domains are the predominant sites of fusion. Here we show that line tension at lipid domain boundaries contributes significant energy to drive gp41-fusion peptide-mediated fusion. This energy, which depends on the hydrophobic mismatch between ordered and disordered lipid domains, may contribute tens of kBT to fusion, that is, it is comparable to the energy required to form a lipid stalk intermediate. Line-active compounds such as vitamin E lower line tension in inhomogeneous membranes, thereby inhibit membrane fusion, and thus may be useful natural viral entry inhibitors.

  10. Chronic Inflammation-Related HPV: A Driving Force Speeds Oropharyngeal Carcinogenesis.

    Science.gov (United States)

    Liu, Xin; Ma, Xiangrui; Lei, Zhengge; Feng, Hao; Wang, Shasha; Cen, Xiao; Gao, Shiyu; Jiang, Yaping; Jiang, Jian; Chen, Qianming; Tang, Yajie; Tang, Yaling; Liang, Xinhua

    2015-01-01

    Oropharyngeal squamous cell carcinoma (OPSCC) has been known to be a highly aggressive disease associated with human papilloma virus (HPV) infection. To investigate the relationship between HPV and chronic inflammation in oropharyngeal carcinogenesis, we collected 140 oral mucous fresh specimens including 50 OPSCC patients, 50 cancer in situ, 30 precancerous lesions, and 10 normal oral mucous. Our data demonstrated that there was a significantly higher proportion of severe chronic inflammation in dysplastic epithelia in comparison with that in normal tissues (Pchronic inflammation degrees from mild to severe inflammation (Pinflammation response and immune suppression in HPV-positive OPSCC. These indicated that persistent chronic inflammation-related HPV infection might drive oropharyngeal carcinogenesis and MDSCs might pay an important role during this process. Thus, a combination of HPV infection and inflammation expression might become a helpful biomedical marker to predict oropharyngeal carcinogenesis.

  11. What drives interannual variability of hypoxia in Chesapeake Bay: Climate forcing versus nutrient loading?

    Science.gov (United States)

    Li, Ming; Lee, Younjoo J.; Testa, Jeremy M.; Li, Yun; Ni, Wenfei; Kemp, W. Michael; Di Toro, Dominic M.

    2016-03-01

    Oxygen depletion in estuaries is a worldwide problem with detrimental effects on many organisms. Although nutrient loading has been stabilized for a number of these systems, seasonal hypoxia persists and displays large year-to-year variations, with larger hypoxic volumes in wetter years and smaller hypoxic volumes in drier years. Data analysis points to climate as a driver of interannual hypoxia variability, but nutrient inputs covary with freshwater flow. Here we report an oxygen budget analysis of Chesapeake Bay to quantify relative contributions of physical and biogeochemical processes. Vertical diffusive flux declines with river discharge, whereas longitudinal advective flux increases with river discharge, such that their total supply of oxygen to bottom water is relatively unchanged. However, water column respiration exhibits large interannual fluctuations and is correlated with primary production and hypoxic volume. Hence, the model results suggest that nutrient loading is the main mechanism driving interannual hypoxia variability in Chesapeake Bay.

  12. External forcing of earthquake swarms at Alpine regions: example from a seismic meteorological network at Mt. Hochstaufen SE-Bavaria

    Directory of Open Access Journals (Sweden)

    V. Svejdar

    2011-11-01

    Full Text Available In the last few years, it has been shown that above-average rainfall and the following diffusion of excess water into subsurface structures is able to trigger earthquake swarms in the uppermost brittle portion of the Earth's crust. However, there is still an ongoing debate on whether the crust already needs to be in a critical-to-failure state or whether it is sufficient that water is transported rapidly within channels and veins of karst or similar geological formations to the underlying, earthquake-generating layers. Also unknown is the role of other forcing mechanisms, possible co-variables and probably necessary tectonic loading in the triggering process of earthquakes. Because of these problems, we do not use an explicit physical model but instead analyze the meteorological and geophysical data via sophisticated statistical models. ewline We are interested in the influence of a more complete set of possible forcing parameters, including the influence of synthetic earth tides, on the occurrence of earthquake swarms. In this context, regression models are the adequate tool, since the calculation of simple correlations can be confounded by the other variables. Since our outcome variable (the number of quakes is a count, we use Poisson regression models that include the plausible assumption of a Poisson distribution for the counts. For this study, we use nearly continuous recordings of a seismic and meteorological network in the years 2002–2008 at Mt. Hochstaufen in SE-Bavaria. Our non-linear regression model reveals correlations between external forces and the triggering of earthquakes. In addition to the still dominant influence of rainfall, theoretical estimated tidal tilt show some weak influence on the swarm generation. However, the influence of the modeled trend functions shows that rain is by far not the most important forcing mechanism present in the data.

  13. Spatial Patterns and Driving Forces of Greenhouse Land Change in Shouguang City, China

    Directory of Open Access Journals (Sweden)

    Bohua Yu

    2017-03-01

    Full Text Available As an important facet of modern agricultural development, greenhouses satisfy ever-increasing demands for agricultural production and, therefore, constitute a growing proportion of global agriculture. However, just a handful of countries regularly collect statistics on the land cover of greenhouse infrastructure. Even when collected, these data cannot provide the detailed spatial information required for environmental risk assessment. It is, therefore, important to map spatial changes in greenhouse land cover using remote sensing (RS approaches to determine the underlying factors driving these changes. In this paper, we apply a support vector machine (SVM algorithm to identify greenhouse land cover in Shouguang City, China. Enhanced thematic mapper (ETM images were selected as the data source for land use classification in this study as they can be freely acquired and offer the necessary spatial resolution. We then used a binary logistic regression model to quantitatively discern the mechanisms underlying changes in greenhouse land cover. The results of this study show that greenhouse land cover in Shouguang increased by 50.51% between 2000 and 2015, and that 90.39% of this expansion took place between 2010 and 2015. Elevation, slope, precipitation, and the distance to the nearest rural settlements and coastline are all significant factors driving expansion in greenhouse land cover, while distance to the nearest urban areas, rivers, roads, railways, and coastline have contributed to contractions in this land use type. Our research provided a practical approach to allow the detection of changes in greenhouse land cover in the countries with using free or low-cost satellite images.

  14. Effect of external shearing force on exfoliation structure and properties of high-performance epoxy/clay nanocomposites

    Institute of Scientific and Technical Information of China (English)

    LU Hai-jun; ZHANG Bao-yan; CHEN Xiang-bao

    2005-01-01

    To further investigate the influence of organic modifiers (primary amine with catalytic hydrogen and quaternary alkylammonium salt) on exfoliation behavior of clay tactoids, high-speed emulsifying and homogeneous mixing(HEHM) and ball milling were used to exert external shearing force on two organic clay tactoids (termed as MMTDDA and MMTDBDA, respectively), which were organically modified with DoDecyl Amine(DDA) and Dodecyl Benzyl Dimethyl Ammonium chloride(DBDA) ,respectively. The effects of external shearing force on microstructure and properties of both resultant nanocomposites were investigated by X-ray diffractometry(XRD), transmission electron microscopy(TEM) and thermogravimetric analysis(TGA). The results show that whether the clay tactoids are organically modified with catalytic primary amine or quaternary alkylammonium salt, the large agglomerates will not be finely dispersed or exfoliated by conventional mixing (magnetic stirring). After being vigorously sheared by HEHM or ball milling, the dispersion and exfoliation of clay tactoids are increasingly promoted for both MMTDDA and MMTDBDA, and the mechanical properties of the high-performance epoxy/clay nanocomposites are enhanced. For epoxy/MMTDDA nanocomposites, impact strength can be increased up to 44.5 kJ/m2 from 32.1 kJ/m2 , which is about 39% higher than that of pristine matrix, and the flexural strength is enhanced by about 4%. A similar enhancement for epoxy/MMTDBDA nanocomposites has also been achieved. Improvement on thermal stability of epoxy/clay nanocomposites is dependent on the exfoliation of clay layers and molecular structure of the modifiers. The onset temperature is increased with the clay loading decreasing from 5% or higher content to 3% (mass fraction), and the DBDA modifier with the heat-resistant benzyl may also improve the stability of epoxy/MMTDBDA nanocomposites.

  15. The importance of ENSO nonlinearities in tropical pacific response to external forcing

    Science.gov (United States)

    Karamperidou, Christina; Jin, Fei-Fei; Conroy, Jessica L.

    2016-12-01

    Tropical Pacific climate varies at interannual, decadal and centennial time scales, and exerts a significant influence on global climate. Climate model projections exhibit a large spread in the magnitude and pattern of tropical Pacific warming in response to greenhouse-gas forcing. Here, we show that part of this spread can be explained by model biases in the simulation of interannual variability, namely the El Niño/Southern Oscillation (ENSO) phenomenon. We show that models that exhibit strong ENSO nonlinearities simulate a more accurate balance of ENSO feedbacks, and their projected tropical Pacific sea surface temperature warming pattern is closely linked to their projected ENSO response. Within this group, models with ENSO nonlinearity close to observed project stronger warming of the cold tongue, whereas models with stronger than observed ENSO nonlinearity project a more uniform warming of the tropical Pacific. These differences are also manifest in the projected changes of precipitation patterns, thereby highlighting that ENSO simulation biases may lead to potentially biased projections in long-term precipitation trends, with great significance for regional climate adaptation strategies.

  16. Theoretical analysis of ferromagnetic microparticles in streaming liquid under the influence of external magnetic forces

    Science.gov (United States)

    Brandl, Martin; Mayer, Michael; Hartmann, Jens; Posnicek, Thomas; Fabian, Christian; Falkenhagen, Dieter

    2010-09-01

    The microsphere based detoxification system (MDS) is designed for high specific toxin removal in extracorporeal blood purification using functionalized microparticles. A thin wall hollow fiber membrane filter separates the microparticle-plasma suspension from the bloodstream. For patient safety, it is necessary to have a safety system to detect membrane ruptures that could lead to the release of microparticles into the bloodstream. A non-invasive optical detection system including a magnetic trap is developed to monitor the extracorporeal venous bloodstream for the presence of released microparticles. For detection, fluorescence-labeled ferromagnetic beads are suspended together with adsorbent particles in the MDS circuit. In case of a membrane rupture, the labeled particles would be released into the venous bloodstream and partly captured by the magnetic trap of the detector. A physical model based on fluidic, gravitational and magnetic forces was developed to simulate the motion and sedimentation of ferromagnetic particles in a magnetic trap. In detailed simulation runs, the concentrations of accumulated particles under different applied magnetic fields within the magnetic trap are shown. The simulation results are qualitatively compared with laboratory experiments and show excellent accordance. Additionally, the sensitivity of the particle detection system is proofed in a MDS laboratory experiment by simulation of a membrane rupture.

  17. Theoretical analysis of ferromagnetic microparticles in streaming liquid under the influence of external magnetic forces

    Energy Technology Data Exchange (ETDEWEB)

    Brandl, Martin, E-mail: martin.brandl@donau-uni.ac.a [Center for Biomedical Technology, Danube University Krems, Krems (Austria); Mayer, Michael [University of Applied Sciences, St. Poelten (Austria); Hartmann, Jens; Posnicek, Thomas [Center for Biomedical Technology, Danube University Krems, Krems (Austria); Fabian, Christian [University of Applied Sciences, St. Poelten (Austria); Falkenhagen, Dieter [Center for Biomedical Technology, Danube University Krems, Krems (Austria)

    2010-09-15

    The microsphere based detoxification system (MDS) is designed for high specific toxin removal in extracorporeal blood purification using functionalized microparticles. A thin wall hollow fiber membrane filter separates the microparticle-plasma suspension from the bloodstream. For patient safety, it is necessary to have a safety system to detect membrane ruptures that could lead to the release of microparticles into the bloodstream. A non-invasive optical detection system including a magnetic trap is developed to monitor the extracorporeal venous bloodstream for the presence of released microparticles. For detection, fluorescence-labeled ferromagnetic beads are suspended together with adsorbent particles in the MDS circuit. In case of a membrane rupture, the labeled particles would be released into the venous bloodstream and partly captured by the magnetic trap of the detector. A physical model based on fluidic, gravitational and magnetic forces was developed to simulate the motion and sedimentation of ferromagnetic particles in a magnetic trap. In detailed simulation runs, the concentrations of accumulated particles under different applied magnetic fields within the magnetic trap are shown. The simulation results are qualitatively compared with laboratory experiments and show excellent accordance. Additionally, the sensitivity of the particle detection system is proofed in a MDS laboratory experiment by simulation of a membrane rupture.

  18. Driving force for the hydration of the swelling clays: case of montmorillonites saturated with alkaline-earth cations.

    Science.gov (United States)

    Salles, Fabrice; Douillard, Jean-Marc; Bildstein, Olivier; Gaudin, Cedric; Prelot, Benedicte; Zajac, Jerzy; Van Damme, Henri

    2013-04-01

    Important structural modifications occur in swelling clays upon water adsorption. The multi-scale evolution of the swelling clay structure is usually evidenced by various experimental techniques. However, the driving force behind such phenomena is still not thoroughly understood. It appears strongly dependent on the nature of the interlayer cation. In the case of montmorillonites saturated with alkaline cations, it was inferred that the compensating cation or the layer surface could control the hydration process and thus the opening of the interlayer space, depending on the nature of the interlayer cation. In the present study, emphasis is put on the impact of divalent alkaline-earth cations compensating the layer charge in montmorillonites. Since no experimental technique offers the possibility of directly determining the hydration contributions related to interlayer cations and layer surfaces, an approach based on the combination of electrostatic calculations and immersion data is developed here, as already validated in the case of montmorillonites saturated by alkaline cations. This methodology allows to estimate the hydration energy for divalent interlayer cations and therefore to shed a new light on the driving force for hydration process occurring in montmorillonites saturated with alkaline-earth cations. Firstly, the surface energy values obtained from the electrostatic calculations based on the Electronegativity Equalization Method vary from 450 mJ m(-2) for Mg-montmorillonite to 1100 mJ m(-2) for Ba-montmorillonite. Secondly, considering both the hydration energy for cations and layer surfaces, the driving force for the hydration of alkaline-earth saturated montmorillonites can be attributed to the interlayer cation in the case of Mg-, Ca-, Sr-montmorillonites and to the interlayer surface in the case of Ba-montmorillonites. These results explain the differences in behaviour upon water adsorption as a function of the nature of the interlayer cation

  19. Sensitivity of oxygen dynamics in the water column of the Baltic Sea to external forcing

    Directory of Open Access Journals (Sweden)

    S. Miladinova

    2010-04-01

    Full Text Available A 1-D biogeochemical/physical model of marine systems has been applied to study the oxygen cycle in four stations of different sub-basins of the Baltic Sea, namely, in the Gotland Deep, Bornholm, Arkona and Fladen. The model consists of the biogeochemical model of Neumann et al. (2002 coupled with the 1-D General Ocean Turbulence Model (GOTM. The model has been forced with meteorological data from the ECMWF reanalysis project for the period 1998–2003, producing a six year hindcast which is validated with datasets from the Baltic Environmental Database (BED for the same period. The vertical profiles of temperature and salinity are relaxed towards both profiles provided by 3-D simulations of General Estuarine Transport Model (GETM and observed profiles from BED. Modifications in the parameterisation of the air-sea oxygen fluxes have led to a significant improvement of the model results in the surface and intermediate water layers. The largest mismatch with observations is found in simulating the oxygen dynamics in the Baltic Sea bottom waters. The model results demonstrate the good capability of the model to predict the time-evolution of the physical and biogeochemical variables at all different stations. Comparative analysis of the modelled oxygen concentrations with respect to observation data is performed to distinguish the relative importance of several factors on the seasonal, interannual and long-term variations of oxygen. It is found that natural physical factors, like the magnitude of the vertical turbulent mixing, wind speed and the variation of temperature and salinity fields are the major factors controlling the oxygen dynamics in the Baltic Sea. The influence of limiting nutrients is less pronounced, at least under the nutrient flux parameterisation assumed in the model.

  20. Scientific Élan Vital: Entropy Deficit or Inhomogeneity as a Unified Concept of Driving Forces of Life in Hierarchical Biosphere Driven by Photosynthesis

    Directory of Open Access Journals (Sweden)

    Naoki Sato

    2012-02-01

    Full Text Available Life is considered something different from non-living things, but no single driving force can account for all the different aspects of life, which consists of different levels of hierarchy, such as metabolism, cell physiology, multi-cellular development and organization, population dynamics, ecosystem, and evolution. Although free energy is evidently the driving force in biochemical reactions, there is no established relationship between metabolic energy and spatiotemporal organization of living organisms, or between metabolic energy and genetic information. Since Schrödinger pointed out the importance of exporting entropy in maintaining life, misunderstandings of entropy notion have been obstacles in constructing a unified view on the driving forces of life. Here I present a simplified conceptual framework for unifying driving forces of life at various different levels of hierarchy. The key concept is “entropy deficit”, or simply, ‘inhomogeneity’, which is defined as the difference of maximal possible entropy and actual entropy. This is equivalent to information content in genetic information and protein structure, and is also defined similarly for non-homogeneous structures in ecosystems and evolution. Entropy deficit or inhomogeneoity is a unified measure of all driving forces of life, which could be considered a scientific equivalent to ‘élan vital’ of Bergson.

  1. Embryo as epiphenomenon: some cultural, social and economic forces driving the stem cell debate.

    Science.gov (United States)

    Green, R M

    2008-12-01

    Our human embryonic stem cell debates are not simply about good or bad ethical arguments. The fetus and the embryo have instead become symbols for a larger set of value conflicts occasioned by social and cultural changes. Beneath our stem cell debates lie conflicts between those who would privilege scientific progress and individual choice and others who favour the sanctity of family life and traditional family roles. Also at work, on both the national and international levels, is the use of the embryo by newly emergent social groups to express resentment against cultural elites. The organisational needs of religious groups have also played a role, with the issue of protection of the embryo and fetus serving as a useful means of rallying organisational allegiance in the Roman Catholic and evangelical communities. Because the epiphenomenal moral positions on the status and use of the embryo are driven by the powerful social, cultural or economic forces beneath them, they will most likely change only with shifts in the underlying forces that sustain them.

  2. The Role of CO2 Physiological Forcing in Driving Future Precipitation Variability and Precipitation Extremes

    Science.gov (United States)

    Skinner, C. B.; Poulsen, C. J.

    2015-12-01

    Transpired water contributes roughly 25% to total precipitation over the Earth's land surface. In addition to transpiration's impact on climatological mean precipitation, recent work suggests that transpiration reduces daily and intraseasonal precipitation variability in tropical forest regions. Projected increases in the concentration of CO2 are expected to reduce transpiration through changes in plant physiology (termed the CO2 physiological effect). Here, we use an ensemble of climate model experiments to assess the potential contribution of the CO2 physiological effect to future changes in precipitation variability and extreme precipitation events. Within our model simulations, precipitation responses to the physiological effects of increased CO2 concentrations are greatest throughout the tropics. In most tropical forest regions CO2 physiological forcing increases the annual number of dry (less than 0.1 mm/day) and extremely wet (rainfall exceeds 95th percentile) days. Changes in precipitation are primarily driven by an increase in surface temperature and subsequent changes in atmospheric stability and moisture convergence over vegetated tropical land regions. Our results suggest that the plant physiological response to CO2 forcing may serve as an important contributor to future precipitation variability in the tropics, and that future work should aim to reduce uncertainty in the response of plant physiology to changes in climate.

  3. 利益相关都外部压力下企业碳减排驱动机制探究%Driving Mechanism of Enterprise’Carbon Emission Reduction Under External Pressure of Stakeholders

    Institute of Scientific and Technical Information of China (English)

    代文; 易智慧

    2016-01-01

    Under the influence of the global energy crisis and greenhouse effect among the govern-ments around the world.However,Chinese enterprises are often found to be reluctant to reduce carbon emission,poor in the effects of carbon reduction,and deficient in system designing of re-duce emissions.Therefore,it is necessary to introduce stakeholder theory to explore the driving mechanism in enterprises’reduction of carbon emissions.This paper first analyzes the present situation of carbon emission reduction and its existing problems.Secondly,from the perspective of stakeholders,combining external driving force to reduce carbon emissions with enterprise's stakeholders such as external organizations,it analyzes the driving mechanism of enterprises'car-bon emission reduction under the pressure of stakeholders.Finally,based on the pressure of stakeholders to reduce carbon emissions,this paper proposes some suggestions to promote the enterprises’efforts to reduce carbon emission.%在全球性能源危机以及温室效应的影响下,减少二氧化碳排放量、发展低碳经济已然成为各国政府共同关注的话题。但我国企业中普遍存在着自愿碳减排的意愿不强、碳减排的效果不佳和碳减排制度设计缺乏等问题。因此,引入利益相关都理论对企业碳减排驱动机理进行探究:首先,对碳减排实施现状及存在的问题进行分析。其次,从利益相关都的视角,将碳减排驱动力与企业的外部组织机构等众多利益相关都联系起来,分析利益相关都压力下企业碳减排的驱动机制。最后,基于碳减排相关利益都的压力,提出促进企业进行碳减排的政策建议。

  4. The driving force of prophages and CRISPR-Cas system in the evolution of Cronobacter sakazakii

    Science.gov (United States)

    Zeng, Haiyan; Zhang, Jumei; Li, Chensi; Xie, Tengfei; Ling, Na; Wu, Qingping; Ye, Yingwang

    2017-01-01

    Cronobacter sakazakii is an important foodborne pathogens causing rare but life-threatening diseases in neonates and infants. CRISPR-Cas system is a new prokaryotic defense system that provides adaptive immunity against phages, latter play an vital role on the evolution and pathogenicity of host bacteria. In this study, we found that genome sizes of C. sakazakii strains had a significant positive correlation with total genome sizes of prophages. Prophages contributed to 16.57% of the genetic diversity (pan genome) of C. sakazakii, some of which maybe the potential virulence factors. Subtype I-E CRISPR-Cas system and five types of CRISPR arrays were found in the conserved site of C. sakazakii strains. CRISPR1 and CRISPR2 loci with high variable spacers were active and showed potential protection against phage attacks. The number of spacers from two active CRISPR loci in clinical strains was significant less than that of foodborne strains, it maybe a reason why clinical strains were found to have more prophages than foodborne strains. The frequently gain/loss of prophages and spacers in CRISPR loci is likely to drive the quick evolution of C. sakazakii. Our study provides a new insight into the co-evolution of phages and C. sakazakii. PMID:28057934

  5. Farming and forestry land use changes in China and their driving forces from 1900 to 1980

    Institute of Scientific and Technical Information of China (English)

    GE; Quansheng; DAI; Junhu

    2005-01-01

    A variety of agricultural and forestry land use materials, especially those in the first half of 20th century, were collected. According to land use change in this period, the whole country is demarcated into seven regions, Northeast China, North China, Northwest and Loess Plateau, Southeast and Coastal Region, Southwest China, Qinghai-Tibetan Plateau, Inner Mongolia and Xinjiang, in proper order by using Cluster Analysis. The farming and forestry land use change in these regions were analyzed. The results show that the total cultivated land areas increased in this period, especially in the 1950s and 1960s the cultivated land area increased more significantly, but differed in different regions, and the most rapid increasing rate was 2.63 percent a year. On the other hand, the forestry land area was increasing in most parts of this period, especially after 1949. But in most regions, the decrease of forestry land area at the end of 1970s is also very obvious. It is regarded that the population increase, food production, natural disasters and some related government policies were among the main driving factors for farming and forestry land use change.

  6. Regulatory gene mutation: a driving force behind group a Streptococcus strain- and serotype-specific variation.

    Science.gov (United States)

    Sarkar, Poulomee; Sumby, Paul

    2017-02-01

    Data from multiple bacterial pathogens are consistent with regulator-encoding genes having higher mutation frequencies than the genome average. Such mutations drive both strain- and type- (e.g., serotype, haplotype) specific phenotypic heterogeneity, and may challenge public health due to the potential of variants to circumvent established treatment and/or preventative regimes. Here, using the human bacterial pathogen the group A Streptococcus (GAS; S. pyogenes) as a model organism, we review the types and regulatory-, phenotypic-, and disease-specific consequences of naturally occurring regulatory gene mutations. Strain-specific regulator mutations that will be discussed include examples that transform isolates into hyper-invasive forms by enhancing expression of immunomodulatory virulence factors, and examples that promote asymptomatic carriage of the organism. The discussion of serotype-specific regulator mutations focuses on serotype M3 GAS isolates, and how the identified rewiring of regulatory networks in this serotype may be contributing to a decades old epidemiological association of M3 isolates with particularly severe invasive infections. We conclude that mutation plays an outsized role in GAS pathogenesis and has clinical relevance. Given the phenotypic variability associated with regulatory gene mutations, the rapid examination of these genes in infecting isolates may inform with respect to potential patient complications and treatment options.

  7. Tendency to occupy a statistically dominant spatial state of the flow as a driving force for turbulent transition

    CERN Document Server

    Chekmarev, Sergei F

    2012-01-01

    A simple analytical model for a turbulent flow is proposed, which considers the flow as a collection of localized spatial structures that are composed of elementary "cells" in which the state of the particles (atoms or molecules) is uncertain. The Reynolds number is associated with the ratio between the total phase volume for the system and that for the elementary cell. Calculating the statistical weights of the collections of the localized structures, it is shown that as the Reynolds number increases, the elementary cells group into the localized structures, which successfully explains the onset of turbulence and some other characteristic properties of turbulent flows. It is also shown that the basic assumptions underlying the model are involved in the derivation of the Navier-Stokes equation, which suggests that the driving force for the turbulent transition described with the hydrodynamic equations is essentially the same as in the present model, i.e. the tendency of the system to occupy a statistically do...

  8. Solvent driving force ensures fast formation of a persistent and well-separated radical pair in plant cryptochrome

    DEFF Research Database (Denmark)

    Lüdemann, Gesa; Solov'yov, Ilia; Kubar, Tomás

    2015-01-01

    radical pair has despite various theoretical and experimental efforts not been unambiguously identified yet. We challenge this unambiguity through a unique quantum mechanical molecular dynamics approach where we perform electron transfer dynamics simulations taking into account the motion of the protein......The photoreceptor protein cryptochrome is thought to host, upon light absorption, a radical pair which is sensitive to very weak magnetic fields, endowing migratory birds with a magnetic compass sense. The molecular mechanism which leads to formation of a stabilised, magnetic field sensitive...... upon the electron transfer. This approach allows us to follow the time evolution of the electron transfer in an unbiased fashion and to reveal the molecular driving force which ensures fast electron transfer in cryptochrome guaranteeing formation of a persistent radical pair suitable...

  9. Driving forces behind the increasing cardiovascular treatment intensity.A dynamic epidemiologic model of trends in Danish cardiovascular drug utilization.

    DEFF Research Database (Denmark)

    Kildemoes, Helle Wallach; Andersen, Morten

    followed with respect to out-of-hospital redemptions of cardiovascular prescription drugs in the period 1996-2005. The impact of population ageing on cardiovascular treatment intensity was investigated by comparing crude and age/gender standardised intensities. Epidemiologic model: We developed a three...... prevalence. Conclusions: Increasing cardiovascular treatment intensity was driven by increases in age/gender specific drug use - rather than by population ageing. Although the increased prevalence of use in all age groups reflects an increasing incidence, recruitment of long-term users is expected to add......Background: In many Western countries cardiovascular treatment intensity (DDD/1000 inhabitants/day, DDD/TID) has grown substantially during the last decades. Changed drug utilization pattern - rather than population ageing - was hypothesized to be the main driving force behind the growth...

  10. Solvent driving force ensures fast formation of a persistent and well-separated radical pair in plant cryptochrome

    DEFF Research Database (Denmark)

    Lüdemann, Gesa; Solov'yov, Ilia; Kubar, Tomás;

    2015-01-01

    The photoreceptor protein cryptochrome is thought to host, upon light absorption, a radical pair which is sensitive to very weak magnetic fields, endowing migratory birds with a magnetic compass sense. The molecular mechanism which leads to formation of a stabilised, magnetic field sensitive radi...... upon the electron transfer. This approach allows us to follow the time evolution of the electron transfer in an unbiased fashion and to reveal the molecular driving force which ensures fast electron transfer in cryptochrome guaranteeing formation of a persistent radical pair suitable...... for magnetoreception. We argue that this unraveled molecular mechanism is a general principle inherent to all proteins of the cryptochrome/photolyase family and that cryptochromes are, therefore, tailored to potentially function as efficient chemical magnetoreceptors....

  11. Analysis on Temporal and Spatial Changes and Driving Forces of Poverty-Stricken Areas in Hebei Province

    Institute of Scientific and Technical Information of China (English)

    Shi Xiaoli; Yuan Jinguo; Wang Wei

    2005-01-01

    This paper takes poverty-stricken county as the basic unit, and selects net income per peasant to study the poverty status in Hebei Province during 1986~2000.Temporal and spatial changes of povertystricken areas are analyzed. The result shows that poverty-stricken areas in Hebei Province distributed concentratedly and the areas decreased during 1986~2000, the net income per peasant was on the rise with an increasing speed in off-poverty counties being slightly higher than that in poverty-stricken counties, but the growth rate was extremely unstable,rising slowly in off-poverty counties while dropping in poverty-stricken counties. The main driving forces that influenced temporal and spatial changes were economic development of the whole province,ecological environment quality, infrastructure conditions and radiation of the key city. On this basis, some anti-poverty countermeasures suitable to local conditions are proposed.

  12. On the possibility of the electron polarization to be the driving force for the C60-TMB nanowire growth

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Geng, Junfeng; Solov'yov, Andrey V.;

    2009-01-01

    The effect of electron polarization has been suggested to explain the exceptionally large length-to width aspect ratio (more than 3000) in recently observed C_60-based nanowires. The theoretical estimates performed in the present Letter show that at room temperature the effect of electron...... polarization is negligibly small and, therefore, cannot become the driving force for nanowire growth along one preferential direction. Experimental measurements are in agreement with the theoretical analysis: the nanowires have been observed to emerge from the polar 1,2,4-trimethylbenzene and non-polar 1......,3,5-trimethylbenzene solution of C_60, while no nanowires from polar toluene, 1,2,3-trimethylbenzene and non-polar benzene solutions could be recorded....

  13. Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012

    Science.gov (United States)

    Muresan, I. S.; Khan, S. A.; Aschwanden, A.; Khroulev, C.; Bjork, A. A.; Box, J. E.

    2014-12-01

    Greenland's main outlet glaciers have more than doubled their contribution to global sea-level rise over the past decade through acceleration of ice discharge. One of the triggering mechanisms is a reduction in resistance (buttressing) at the marine based glacier front (i.e. through reduced thickness or retreat of the floating tongue of a glacier) caused by enhanced calving or a longer-term thinning due to a mass deficit of the ice sheet. Recent findings indicate the reduced buttressing at the marine terminus is responsible for the recent dynamic changes observed in Greenland, but the controlling processes and triggering mechanisms are still unclear. Furthermore, our current understanding is almost entirely based on observations from a short-term record spanning only from a year to a decade, and is characterized by short-term fluctuations and therefore not representative for longer-term trends of several decade time scales. Here, we study the mechanisms controlling dynamic changes at the terminus of Jakobshavn Isbræ over a period of 172 years. The recent glacier acceleration began in late 1990s but there is evidence for glacier retreat of comparable magnitude in 1930s, when a similarly warm period occurred. To control the acceleration and retreat based on observed front positions during 1840-2012, we use an ocean model modifier that implements forcing at the ocean boundary using melange back pressure offsets. The mean temperature anomaly in west Greenland, the North Atlantic oscillation (NAO) winter index and the Atlantic multidecadal oscillation (AMO) index anomalies for the period 1900-2012 sustain our modelling results. The modelled surface elevation changes near the front are considered and compared with observed surface elevation changes for the period 1880-2012. Furthermore, the modelled mass loss signal between 1997-2012 is validated based on ice mass change observations which we estimate using altimeter surveys from NASA's ATM flights during 1997

  14. Error signals driving locomotor adaptation

    DEFF Research Database (Denmark)

    Choi, Julia T; Jensen, Peter; Nielsen, Jens Bo

    2016-01-01

    perturbations. Forces were applied to the ankle joint during the early swing phase using an electrohydraulic ankle-foot orthosis. Repetitive 80 Hz electrical stimulation was applied to disrupt cutaneous feedback from the superficial peroneal nerve (foot dorsum) and medial plantar nerve (foot sole) during...... anaesthesia (n = 5) instead of repetitive nerve stimulation. Foot anaesthesia reduced ankle adaptation to external force perturbations during walking. Our results suggest that cutaneous input plays a role in force perception, and may contribute to the 'error' signal involved in driving walking adaptation when...

  15. Study on driving forces of wetland change in the Western Liaohe River basin based on random forest model

    Science.gov (United States)

    Wu, Menghong; Yang, Changbao; Zhang, Yanhong; Lin, Nan

    2017-05-01

    Based on the platform of RS and GIS, random forest progression model is used for study driving force of wetland change in western Liaohe river basin, five influencing factors which include elevation, slope, temperature, precipitation and population density are chosen to establish random forest progression model about the wetland change and the driving factors. Using the the mean value of the prediction accuracy outside the bag calculated by the model to evaluate the importance of the variables. The result indicates that the coefficient of partial correlation between precipitation and wetland density is the largest among the five influencing factors, followed by temperature, population density, elevation and slope is smallest. The influence of natural factors on the change of wetland density is mainly reflected in precipitation and temperature factors, and the precipitation is obviously higher than that of temperature, under the influence of human factors, the influence of population density factor on wetland density is higher than that of elevation and slope factor. The result shows that in the past 40 years, the human activities in the study area have increased the density of wetland to some extent, but it is not the main factor.

  16. Analysis of spatio-temporal pattern and driving force of land cover change using multi-temporal remote sensing images

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Landuse and land cover change is regarded as a good indicator that represents the impact of human activities on earth’s environment.When the large collection of multi-temporal satellite images has become available,it is possible to study a long-term historical process of land cover change.This study aims to investigate the spatio-temporal pattern and driving force of land cover change in the Pearl River Delta region in southern China,where the rapid development has been witnessed since 1980s.The fast economic growth has been associated with an accelerated expansion of urban landuse,which has been recorded by historical remote sensing images.This paper reports the method and outcome of the research that attempts to model spatio-temporal pattern of land cover change using multi-temporal satellite images.The classified satellite images were compared to detect the change from various landuse types to built-up areas.The trajectories of land cover change have then been established based on the time-series of the classified land cover classes.The correlation between the expansion of built-up areas and selected economic data has also been analysed for better understanding on the driving force of the rapid urbanisation process.The result shows that,since early 1990s,the dominant trend of land cover change has been from farmland to urban landuse.The relationship between economic growth indicator(measured by GDP)and built-up area can well fit into a linear regression model with correlation coefficients greater than 0.9.It is quite clear that cities or towns have been sprawling in general,demonstrating two growth models that were closely related to the economic development stages.

  17. Empirical Analysis of Internal Driving Force of Medical Professionalism%医师职业精神内源性驱动力的实证探讨

    Institute of Scientific and Technical Information of China (English)

    于德华; 李建刚; 许树长; 黄红; 刘薇群; 董政军; 程卢山

    2013-01-01

    以“优质护理服务工程”、产科“一贯制”工作模式与传统工作模式为基础,分析了医务人员职业精神内源性驱动力的差异.结果表明:不同工作模式下心理契约有显著差异,变革组高于试点组; “医患交流互动”因素对工作行为发生积极变化的重要性有显著的差异,变革组高于传统组;在相同工作环境下,不同自尊水平的医务人员,其职业精神的表现有显著差异,自尊水平越高,员工满意度和工作敬业度得分越高、工作倦怠得分越低,即职业精神表现越好.提出医师职业精神的内源性驱动力来自3个方面:内部组织赋予医务人员的内心体验,外部顾客(患者)赋予医务人员的内心体验,医务人员自我人格特征.%With comparing "High Quality Nursing Service Project" and "Consistent Obstetrics" with traditional working mode, the difference of internal driving force of medical professionalism is analyzed. Results indicate that the difference of psychological contract in different working modes is significant, and the score of reform group is higher than that in traditional group; the importance of the factor of "doctor-patient communication" which has caused positive changes of work behavior is significantly different in different working modes, and the score of reform group is higher than that in traditional group; in the same working mode, medical staffs having different self-esteem levels have different employee satisfaction, and the higher level of self-esteem medical staffs have, the higher their employee satisfaction. The internal driving force of medical professionalism lies in 3 aspects: inner experience from internal organization, inner feeling from external customer (patients), and self personality characteristics of medical staffs.

  18. Molecular dynamics study of response of liquid N,N-dimethylformamide to externally applied electric field using a polarizable force field

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Weimin; Niu, Haitao; Lin, Tong; Wang, Xungai; Kong, Lingxue [Institute for Frontier Materials, Deakin University, Waurn Ponds VIC 3216 (Australia)

    2014-01-28

    The behavior of Liquid N,N-dimethylformamide subjected to a wide range of externally applied electric fields (from 0.001 V/nm to 1 V/nm) has been investigated through molecular dynamics simulation. To approach the objective the AMOEBA polarizable force field was extended to include the interaction of the external electric field with atomic partial charges and the contribution to the atomic polarization. The simulation results were evaluated with quantum mechanical calculations. The results from the present force field for the liquid at normal conditions were compared with the experimental and molecular dynamics results with non-polarizable and other polarizable force fields. The uniform external electric fields of higher than 0.01 V/nm have a significant effect on the structure of the liquid, which exhibits a variation in numerous properties, including molecular polarization, local cluster structure, rotation, alignment, energetics, and bulk thermodynamic and structural properties.

  19. Prescription drug advertising: is it a driving force on drug pricing?

    Science.gov (United States)

    Millstein, Lloyd G

    2003-01-01

    It has been shown that drug companies will sell more drugs when they use DTC advertising, but it is also true that many consumers who are suffering--unaware there is help for their symptoms--will learn from these ads that help is available. Advertising to consumers, like advertising to professionals, will continue to be one of the best methods of providing information. Of course, healthcare professionals also have the sales representatives, their colleagues, medical journals, and medical conventions as additional options for needed information. The consumer may or may not use other methods, such as the Internet, the library or friends or family, but the advertising is a starting point for a dialogue. If the DTC ad provides consumers with "information," which is different from "advertising," the drug company will be providing a worthwhile service to consumers and potential patients. No doubt consumers will begin demanding higher quality information from DTC ads and will frown upon the ads that are blatantly trying just to sell a drug. It will also reap the benefits of improved consumer awareness and patient compliance. A DTC ad that is consumer-friendly, does not use fear appeal, is educational in tone, and downplays the "hard sell" and hype will go a long way in offering important information to the casual observer. Oversight by the FDA will ensure the information meets the requirements they have set down for prescription drug advertising. That is, advertising will be truthful and fairly balanced and will meet what the government, consumers and, no doubt, the medical community wants. Attempting to control drug costs, by controlling advertising, will not be an easy task. This has an implication across all product areas, not just drugs. DTC advertising has become a lightening rod for cost containment issues, but is it alone driving demand for prescription products? I don't think so.

  20. Transitions in Land Use Architecture under Multiple Human Driving Forces in a Semi-Arid Zone

    Directory of Open Access Journals (Sweden)

    Issa Ouedraogo

    2015-07-01

    Full Text Available The present study aimed to detect the main shifts in land-use architecture and assess the factors behind the changes in typical tropical semi-arid land in Burkina Faso. Three sets of time-series LANDSAT data over a 23-year period were used to detect land use changes and their underpinning drivers in multifunctional but vulnerable ecologies. Group discussions in selected villages were organized for mapping output interpretation and collection of essential drivers of change as perceived by local populations. Results revealed profound changes and transitions during the study period. During the last decade, shrub and wood savannahs exhibited high net changes (39% and −37% respectively with a weak net positive change for cropland (only 2%, while cropland and shrub savannah exhibited high swap (8% and 16%. This suggests that the area of cropland remained almost unchanged but was subject to relocation, wood savannah decreased drastically, and shrub savannah increased exponentially. Cropland exhibited a null net persistence while shrub and wood savannahs exhibited positive and negative net persistence (1.91 and −10.24, respectively, indicating that there is movement toward agricultural intensification and wood savannah tended to disappear to the benefit of shrub savannah. Local people are aware of the changes that have occurred and support the idea that illegal wood cutting and farming are inappropriate farming practices associated with immigration; absence of alternative cash generation sources, overgrazing and increasing demand for wood energy are driving the changes in their ecosystems. Policies that integrate restoration and conservation of natural ecosystems and promote sustainable agroforestry practices in the study zone are highly recommended.

  1. Spatial pattern of land use change and its driving force in Jiangsu Province.

    Science.gov (United States)

    Du, Xindong; Jin, Xiaobin; Yang, Xilian; Yang, Xuhong; Zhou, Yinkang

    2014-03-18

    Scientific interpretation of the mechanism of land use change is important for government planning and management activities. This study analyzes the land use change in Jiangsu Province using three land use maps of 2000, 2005 and 2008. The study results show that there was a significant change in land use. The change was mainly characterized by a continuous built-up land expansion primarily at the expense of cropland loss, and the trend became increasingly rapid. There was an obvious regional difference, as most of the cropland loss or built-up land expansion took place in southern Jiangsu, where the rate of built-up land expansion was faster than in central and northern Jiangsu. Meanwhile, the spatial pattern changed remarkably; in general, the number of patches (NumP) showed a declining trend, and the mean patch size (MPS) and patch size standard deviation (PSSD) displayed increase trends. Furthermore, the relative importance of selected driven factors was identified by principal component analysis (PCA) and general linear model (GLM). The results showed that not only the relative importance of a specific driving factor may vary, but the driven factors may as well. The most important driven factor changed from urban population (UP), secondary gross domestic product (SGDP) and gross domestic product (GDP) during 2000-2005 to resident population (RP), population density (POD) and UP during 2005-2008, and the deviance explained (DE) decreased from 91.60% to 81.04%. Policies also had significant impacts on land use change, which can be divided into direct and indirect impacts. Development policies usually had indirect impacts, particularly economic development policies, which promote the economic development to cause land use change, while land management policies had direct impacts. We suggest that the government should think comprehensively and cautiously when proposing a new development strategy or plan.

  2. Impacts of Human Activity on Biodiversity-An Approach to Driving Force Indicators%人类活动对生物多样性的影响

    Institute of Scientific and Technical Information of China (English)

    Richard Dawson; 曹志平

    2005-01-01

    The impact of human activity on biodiversity is very complicated, making it difficult to design practical indicators for assessment. Currently, state and response indicators are listed within Chapter 15 of Agenda 21, but no mention is made of driving force indicators and how they relate to biodiversity protection. This paper repre-sents an effort to identify and then operationalize the idea of driving force indicators at national level Five humaninduced factors affecting biodiversity were discussed: (a) habitat loss and fragmentation; (b) overexploitation of resources; (c) species introduction; (d) pollution; and (e) climate change. From these five factors, a subset was selected to serve as possible driving force indicators: (1) habitat loss, (2) the ratio of exotic species to indigenous ones, and (3) the change in pollution status. Although the three indicators are relatively simple, they cover the most important human impacts on biodiversity and offer the potential for further redefinition and ultimate use within the spirit of biodiversity protection.

  3. A Study of the Driving Force Model Revealing Changes in Land Utilization Level Based on 3S Technologies--The Example of Yuanmou, Yunnan, China

    Institute of Scientific and Technical Information of China (English)

    HE Jin-feng; CHEN Guo-jie; YANG Zhong

    2005-01-01

    This paper introduced the theory and approaches of building driving force models revealing the changes in land utilization level by integrating RS, GPS, and GIS technologies based on the example of Yuanmou County of Yunnan Province. We first created the land utilization type database, natural driving forces for land utilization database, and human driving forces for land utilization database. Then we obtained the dependent and the independent variables of changes in land utilization level by exploring various data. Lastly we screened major factors affecting changes in land utilization level by using the po- werful spatial correlation analysis and main component analysis module of GIS and obtained a multivariable linear regression model of the changes in land utilization level by using GIS spatial regression analysis module.

  4. Reverse evolution: driving forces behind the loss of acquired photosynthetic traits.

    Directory of Open Access Journals (Sweden)

    Francisco de Castro

    Full Text Available The loss of photosynthesis has occurred often in eukaryotic evolution, even more than its acquisition, which occurred at least nine times independently and which generated the evolution of the supergroups Archaeplastida, Rhizaria, Chromalveolata and Excavata. This secondary loss of autotrophic capability is essential to explain the evolution of eukaryotes and the high diversity of protists, which has been severely underestimated until recently. However, the ecological and evolutionary scenarios behind this evolutionary "step back" are still largely unknown.Using a dynamic model of heterotrophic and mixotrophic flagellates and two types of prey, large bacteria and ultramicrobacteria, we examine the influence of DOC concentration, mixotroph's photosynthetic growth rate, and external limitations of photosynthesis on the coexistence of both types of flagellates. Our key premises are: large bacteria grow faster than small ones at high DOC concentrations, and vice versa; and heterotrophic flagellates are more efficient than the mixotrophs grazing small bacteria (both empirically supported. We show that differential efficiency in bacteria grazing, which strongly depends on cell size, is a key factor to explain the loss of photosynthesis in mixotrophs (which combine photosynthesis and bacterivory leading to purely heterotrophic lineages. Further, we show in what conditions an heterotroph mutant can coexist, or even out-compete, its mixotrophic ancestor, suggesting that bacterivory and cell size reduction may have been major triggers for the diversification of eukaryotes.Our results suggest that, provided the mixotroph's photosynthetic advantage is not too large, the (small heterotroph will also dominate in nutrient-poor environments and will readily invade a community of mixotrophs and bacteria, due to its higher efficiency exploiting the ultramicrobacteria. As carbon-limited conditions were presumably widespread throughout Earth history, such a

  5. Evolution of cell populations in vitro: peculiarities, driving forces, mechanisms and consequences

    Directory of Open Access Journals (Sweden)

    Kunakh V. A.

    2013-07-01

    Full Text Available This review outlines the major features and distinctions of cell populations, types and directions of selection in such populations. Population-genetic basis for cell adaptation to growth conditions in vitro is elucidated; in particular, peculiarities of genome evolution in the course of cell dedifferentiation and further cell adaptation to growth conditions in passaged culture are evaluated. Main factors of variation and selection in cell populations in vitro, influence of growth conditions on structure of cell populations and some regularities of cultured cells and regenerated plants are considered. Details of creation of stable cell lines-producers of biologically active substances are presented. Views and suppositions of author resulting from analysis of both literature data and own multiyear studies on cell population genetics are set forth. Among others are substantiated such key statements: cell culture in vitro presents dynamically-heterogeneous biological system, clone population, which is developing (evolving as a result of major driving factors of evolution – variation, heredity, selection and drift of genes (genotypes; interaction between these processes determines the biological characteristics of each particular cell line grown in specific conditions; in adaptation of cells to growth conditions in vitro one can single out three periods: the initial population of isolated cells, the period of strain (cell line formation and the established strain. The division into periods is determined by the type, direction and intensity of «natural» selection that acts in cell population. The formed (adapted to growth in vitro strains are genetically heterogeneous, they are characterized by the presence of physiological and genetic homeostasis, which are mostly caused by the action of stabilizing selection; cultured cells of higher plants are able to synthesize practically all classes of secondary (specialized compounds (alkaloids, steroids

  6. Particle motion in a periodic driving flow. The role of added mass force and the finite size of particles

    Science.gov (United States)

    Ruiz Chavarria, Gerardo; Lopez Sanchez, Erick Javier

    2016-11-01

    The motion of particles in a fluid is an open problem. The main difficulty arises from the fact that hydrodynamical forces acting on a particle depend on the flow properties. In addition, the form and the size of particles must be taken into account. In this work we present numerical results of the particle transport in a periodic driving flow in a channel flushing into an open domain. To study the transport of particles we solve the equation of motion for a spherical particle in which we include the drag, the gravity, the buoyancy, the added mass and the history force. Additionally we include the corrections for a particle of finite size. For solving this equation a knowledge of the velocity field is required. To obtain the velocity field we solve the Navier Stokes and the continuity equations with a finite volume method. In the flow under study a vorticity dipole and a spanwise vortex are present, both have an important influence on the motion of particles. The dipole enhances displacement of particles because flow between vortices behaves like a jet and the spanwise vortex produces the lifting and deposition of particles from/to the bottom. We observe clustering of particles both into the channel and in the open domain as observed in coastal systems. The authors acknowledge DGAPA-UNAM by support under project PAPIIT IN115315 "Ondas y estructuras coherentes en dinámica de fluidos".

  7. The generalized Langevin equation revisited: Analytical expressions for the persistence dynamics of a viscous fluid under a time dependent external force

    Science.gov (United States)

    Olivares-Rivas, Wilmer; Colmenares, Pedro J.

    2016-09-01

    The non-static generalized Langevin equation and its corresponding Fokker-Planck equation for the position of a viscous fluid particle were solved in closed form for a time dependent external force. Its solution for a constant external force was obtained analytically. The non-Markovian stochastic differential equation, associated to the dynamics of the position under a colored noise, was then applied to the description of the dynamics and persistence time of particles constrained within absorbing barriers. Comparisons with molecular dynamics were very satisfactory.

  8. Apico-basal forces exerted by apoptotic cells drive epithelium folding.

    Science.gov (United States)

    Monier, Bruno; Gettings, Melanie; Gay, Guillaume; Mangeat, Thomas; Schott, Sonia; Guarner, Ana; Suzanne, Magali

    2015-02-12

    Epithelium folding is a basic morphogenetic event that is essential in transforming simple two-dimensional epithelial sheets into three-dimensional structures in both vertebrates and invertebrates. Folding has been shown to rely on apical constriction. The resulting cell-shape changes depend either on adherens junction basal shift or on a redistribution of myosin II, which could be driven by mechanical signals. Yet the initial cellular mechanisms that trigger and coordinate cell remodelling remain largely unknown. Here we unravel the active role of apoptotic cells in initiating morphogenesis, thus revealing a novel mechanism of epithelium folding. We show that, in a live developing tissue, apoptotic cells exert a transient pulling force upon the apical surface of the epithelium through a highly dynamic apico-basal myosin II cable. The apoptotic cells then induce a non-autonomous increase in tissue tension together with cortical myosin II apical stabilization in the surrounding tissue, eventually resulting in epithelium folding. Together our results, supported by a theoretical biophysical three-dimensional model, identify an apoptotic myosin-II-dependent signal as the initial signal leading to cell reorganization and tissue folding. This work further reveals that, far from being passively eliminated as generally assumed (for example, during digit individualization), apoptotic cells actively influence their surroundings and trigger tissue remodelling through regulation of tissue tension.

  9. Determination of Oxygen Transport Properties from Flux and Driving Force Measurements

    DEFF Research Database (Denmark)

    Dalslet, Bjarke Thomas; Søgaard, Martin; Hendriksen, Peter Vang

    2007-01-01

    We demonstrate that an electrolyte probe can be used to measure the difference in oxygen chemical potential across the surface, when an oxygen flux is forced through an oxygen permeable membrane disk. The oxygen flux as well as the total oxygen chemical potential difference is carefully controlled...... by an oxygen pump. The developed method is tested on a (La0.6Sr0.4)0.99Co0.2Fe0.8O3−delta membrane. An La0.75Sr0.25MnO3/Y0.16Zr0.84O1.92/La0.75Sr0.25MnO3 oxygen pump was attached to one side of the membrane. A conical Ce0.9Gd0.1O1.95 (CG10) electrolyte probe was pressed against the other side of the membrane....... The voltage difference between the base and the tip of the CG10 probe was recorded with an applied oxygen flux through the membrane. This voltage was used to extract precise values of the surface exchange rate constant, kO. Using these values of kO, the vacancy diffusion factor, Dv0, could be extracted from...

  10. [The driving force in the thinking of Norbert Elias. An attempt at psychoanalytic interpretation].

    Science.gov (United States)

    Schröter, M

    1993-07-01

    The theory of civilization proposed by the eminent sociologist Norbert Elias, who died in 1990, has its roots in Freud's theory of culture. Elias always denied the importance of personal factors in connection with his work, but as has been demonstrated in connection with artists such as Leonardo da Vinci and indeed Freud himself, this does not make it any the less legitimate to go in search of those infantile/unconscious motifs and affective sources powering Elias' prodigious scholarly creativity and informing his work, in however sublimated a form. Proceeding from the observation that successful scholarly or artistic production represents a synthesis of the forces of id, ego and super-ego, i.e. of affect, knowledge and conscience, the author demonstrates that concerns of central moment to Elias' thinking--commitment and non-involvement, establishment and outsider, the restraining of aggression in the civilizational process, interdependence of individuals--are partly the product of early experiences which Elias was able to turn to fruitful account in his work.

  11. Optimized comb drive finger shape for shock-resistant actuation

    NARCIS (Netherlands)

    Engelen, Johan B.C.; Abelmann, Leon; Elwenspoek, Miko C.

    2010-01-01

    This work presents the analytical solution, realization and measurement of a comb drive with finger shapes optimized for shock-resistant actuation. The available force for actuating an external load determines how large shock forces can be compensated for. An analytical expression is presented for t

  12. Supply Chain Management as a Driving Force for Generating Competitive Advantage for Dairy Companies

    Directory of Open Access Journals (Sweden)

    Irina Olegovna Poleshkina

    2016-11-01

    Full Text Available The study aims to uncover the reserves to generate competitive advantages for the participants of the market of perishables in the case of the dairy sector due to the formation of effective supply chains, as this category of goods is the most demanding in terms of periods and conditions of transportation and terms of preservation. The research technique is based on the concepts of value chains and supply chain management. In order to optimize the distribution of functions between the participants of the dairy chain a process-based approach has been applied. The research has revealed the main reasons for high aggregate costs and the places of their formation at each stage of the dairy supply chain. The article proposes the mechanisms to address three main problems arising from the process of building relations between the participants of the dairy supply chain in Russia. These problems are associated with a disproportionate margin distribution between the participants of the chain, with non-compliance of the quality of raw milk with the requirements for the production of specific types of dairy products, and with distrust of the supply chain participants, which increases transaction costs and forces to create reserve supplies which reduce the competitiveness of the whole dairy supply chain in general. In order to improve the competitiveness of all participants in the dairy chain, the article presents several mechanisms for solving these problems. The first is margin distribution based on the costs incurred by each participant of the dairy chain. The second is the use of a mathematical model to determine the assortment of goods of a dairy enterprise on the basis of the incoming volume and quality of raw milk according to the seasonal factor and the demand for dairy products. The third is the feasibility of refusal from the formation of reserve supplies by all participants of the dairy chain, which will not only minimize aggregate costs, but also

  13. Multi Satellites Monitoring of Land Use/Cover Change and Its Driving Forces in Kashgar Region, China

    Science.gov (United States)

    Maimaitiaili, Ayisulitan; Aji, xiaokaiti; Kondoh, Akihiko

    2016-04-01

    Multi Satellites Monitoring of Land Use/Cover Change and Its Driving Forces in Kashgar Region, China Ayisulitan Maimaitiaili1, Xiaokaiti Aji2 Akihiko Kondoh2 1Graduate School of Science, Chiba University, Japan 2Center for Environmental Remote Sensing, Chiba University The spatio-temporal changes of Land Use/Cover (LUCC) and its driving forces in Kashgar region, Xinjiang Province, China, are investigated by using satellite remote sensing and a geographical information system (GIS). Main goal of this paper is to quantify the drivers of LUCC. First, considering lack of the Land Cover (LC) map in whole study area, we produced LC map by using Landsat images. Land use information from Landsat data was collected using maximum likelihood classification method. Land use change was studied based on the change detection method of land use types. Second, because the snow provides a key water resources for stream flow, agricultural production and drinking water for sustaining large population in Kashgar region, snow cover are estimated by Spot Vegetation data. Normalized Difference Snow Index (NDSI) algorithm are applied to make snow cover map, which is used to screen the LUCC and climate change. The best agreement is found with threshold value of NDSI≥0.2 to generate multi-temporal snow cover and snowmelt maps. Third, driving forces are systematically identified by LC maps and statistical data such as climate and socio-economic data, regarding to i) the climate changes and ii) socioeconomic development that the spatial correlation among LUCC, snow cover change, climate and socioeconomic changes are quantified by using liner regression model and negative / positive trend analysis. Our results showed that water bodies, bare land and grass land have decreasing notably. By contrast, crop land and urban area have continually increasing significantly, which are dominated in study area. The area of snow/ice have fluctuated and has strong seasonal trends, total annual snow cover

  14. Orbital motion in generalized static fields of FELs accounting for axial magnetic field, beam forces, undulator and external focusing

    Energy Technology Data Exchange (ETDEWEB)

    Papadichev, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)

    1995-12-31

    Various types of undulators with or without axial magnetic field are used in FELs. Supplementary beam focusing can be applied by wedging, inclining or profiling pole faces of plan undulators or superposing external focusing magnetic fields in addition to undulator own focusing. Space-charge forces influence significantly particle motion in high-current, low-energy electron beams. Finally, one can use simultaneously two or more different undulators for some specific purpose: more efficient and selective higher harmonics generation, changing polarization types and direction, gain enhancement in double-period undulator etc. All these cases can be treated by solving the generalized equations of transverse orbital motion in a linear approximation, which is widely used for orbit calculation, gives sufficient accuracy for practical purposes and allows to consider many variants and optimize the chosen one. The undulator field is described as a field of two plane undulators with mutually orthogonal fields and an arbitrary axial (phase) shift between them. Various values of the phase shift correspond to right- or left-handed helical undulators, plane undulator of different polarization etc. The general formulae are reduced to forms that allow easier examination of particular cases: planar or helical undulator combined with axial magnetic field or without it, gyroresonance, limiting beam current, polarization etc.

  15. Establishment and validation of standardized animal models of spinal cord injury by normal external force-caused fracture dislocation

    Institute of Scientific and Technical Information of China (English)

    Weibing Shuang; Qiang Liu; Shoubin Jiao; Yang Yang

    2011-01-01

    The duplication of animal models plays a key role in spinal cord injury research; however, there has been limited study into normal, external force-derived fracture dislocation. This study adopted experimental devices, designed in-house, to construct standardized ventral and dorsal spinal cord injury animal models of 6 g and 17 g falling from a height of 2, 4, and 10 cm, and 15, 30 or 50 g transversal compression on the spinal cord. The results showed that gradual increases in the degree of histopathological injury led to decreased Tarlov and Basso, Beattie and Bresnahan scores for the behavioral test, and increased Ashworth scores for the hind limb. Furthermore, there was a gradual decline in the slope test in the rats with dorsal spinal cord injury that correlated to increases in the falling substance weight or falling height. Similar alterations were observed in the ventral spinal cord injured rats, proportional to the increase in compression weight. Our experimental findings indicate that the standardized experimental rat models of dorsal and ventral spinal cord injury are stable, reliable and reproducible.

  16. Toward a Theory of Island Pedogeography: Testing the driving forces for pedological assemblages in archipelagos of different origins

    Science.gov (United States)

    Ibáñez, Juan-José; Effland, William R.

    2011-12-01

    The Theory of Island Biogeography has been based on biodiversity studies and used as a powerful predictive tool. Currently pedogeography does not have a similar theoretical construct. Although island biodiversity and biological assemblages have been topics of widespread interest in biogeography, ecology and conservation biology, soil scientists have conducted few studies of pedodiversity and pedological assemblages in archipelagos. Several studies have demonstrated that pedodiversity and biodiversity patterns have striking similarities in very disparate environments and at different scales, thus it is possible to test for a similar construct of island pedogeography. We analyze similarities and differences in the pedosphere for three archipelagos with different origins: (i) oceanic-intra-plate chains islands (Hawaiian Islands), (ii) oceanic-intra-plate cluster islands (Canary Islands), (iii) non-marine land-bridge islands with volcanism associated with plate boundary conditions (Aegean Islands) and (iv) as a comparison, islands in a nonplate boundary setting (the British Isles). In the Canary Islands, we also compiled selected biological, physiographical, geological and climatic data for further analysis of pedodiversity, climatic diversity, geodiversity and biodiversity. Our pedogeographic analysis of the three archipelagos indicates archipelagos of varying origins contain different soil assemblages with plate tectonics as the main driving force. The similarities between pedodiversity and biodiversity are more remarkable than the differences. We tested the hypothesis that soil taxa distributions on island chains can be modelled as a power function similar to the species-area relationship (SAR) proposed by McArthur and Wilson for archipelagos. The SAR functional relationship has been widely corroborated in other biodiversity studies. The same patterns were obtained for pedodiversity and biodiversity in the British Isles, and after that in the Aegean Archipelago. In

  17. Nonequivalence of membrane voltage and ion-gradient as driving forces for the bacterial flagellar motor at low load.

    Science.gov (United States)

    Lo, Chien-Jung; Leake, Mark C; Pilizota, Teuta; Berry, Richard M

    2007-07-01

    Many bacterial species swim using flagella. The flagellar motor couples ion flow across the cytoplasmic membrane to rotation. Ion flow is driven by both a membrane potential (V(m)) and a transmembrane concentration gradient. To investigate their relation to bacterial flagellar motor function we developed a fluorescence technique to measure V(m) in single cells, using the dye tetramethyl rhodamine methyl ester. We used a convolution model to determine the relationship between fluorescence intensity in images of cells and intracellular dye concentration, and calculated V(m) using the ratio of intracellular/extracellular dye concentration. We found V(m) = -140 +/- 14 mV in Escherichia coli at external pH 7.0 (pH(ex)), decreasing to -85 +/- 10 mV at pH(ex) 5.0. We also estimated the sodium-motive force (SMF) by combining single-cell measurements of V(m) and intracellular sodium concentration. We were able to vary the SMF between -187 +/- 15 mV and -53 +/- 15 mV by varying pH(ex) in the range 7.0-5.0 and extracellular sodium concentration in the range 1-85 mM. Rotation rates for 0.35-microm- and 1-microm-diameter beads attached to Na(+)-driven chimeric flagellar motors varied linearly with V(m). For the larger beads, the two components of the SMF were equivalent, whereas for smaller beads at a given SMF, the speed increased with sodium gradient and external sodium concentration.

  18. Analysis on the multi-dimensional spectrum of the thrust force for the linear motor feed drive system in machine tools

    Science.gov (United States)

    Yang, Xiaojun; Lu, Dun; Ma, Chengfang; Zhang, Jun; Zhao, Wanhua

    2017-01-01

    The motor thrust force has lots of harmonic components due to the nonlinearity of drive circuit and motor itself in the linear motor feed drive system. What is more, in the motion process, these thrust force harmonics may vary with the position, velocity, acceleration and load, which affects the displacement fluctuation of the feed drive system. Therefore, in this paper, on the basis of the thrust force spectrum obtained by the Maxwell equation and the electromagnetic energy method, the multi-dimensional variation of each thrust harmonic is analyzed under different motion parameters. Then the model of the servo system is established oriented to the dynamic precision. The influence of the variation of the thrust force spectrum on the displacement fluctuation is discussed. At last the experiments are carried out to verify the theoretical analysis above. It can be found that the thrust harmonics show multi-dimensional spectrum characteristics under different motion parameters and loads, which should be considered to choose the motion parameters and optimize the servo control parameters in the high-speed and high-precision machine tools equipped with the linear motor feed drive system.

  19. Spatiotemporal Pattern and Driving Forces of Arable Land-Use Intensity in China: Toward Sustainable Land Management Using Emergy Analysis

    Directory of Open Access Journals (Sweden)

    Hualin Xie

    2014-05-01

    Full Text Available The level of arable land-use intensity has important impacts on food security and rural sustainable development. Using the emergy method, we investigate the spatial disparities and driving forces of arable land-use intensity in China from 1999 to 2008 at the national, regional and provincial levels. The empirical results show that chemical fertilizer was the largest component of agricultural inputs and that agricultural diesel oil recorded the highest growth rate. The degree of heterogeneities in arable land-use intensity in China showed a decreasing trend, which resulted mainly from the differences among the eastern, northeastern, central and western regions. The regional disparities in labor, pesticides and plastic sheeting decreased from 1999 to 2008. The per capita annual net incomes of household operations and the agricultural policies had a significant positive correlation with total inputs, fertilizer inputs, pesticide inputs and agricultural plastic sheeting. In addition, the nonagricultural population had a greater impact on agricultural plastic sheeting. Finally, we suggest that there is an urgent need to focus on the effects of chemical fertilizer and pesticide inputs on the ecological environment. Agricultural support policies should be introduced for the poor agricultural production provinces.

  20. Analysis of the Influencing Factors and Key Driving Force concerning the Efficiency of Green Supply Chain of Fruits and Vegetables

    Institute of Scientific and Technical Information of China (English)

    Yingtang; LI; Zhong; QIAO

    2014-01-01

    Like the general green supply chain,the green supply chain of fruits and vegetables also requires low negative effects of the environment and high resource utilization rate,as well as the healthiness and freshness of fruits and vegetables.Currently,the level of development of the green supply chain of fruits and vegetables is low in China,and the freshness of fruits and vegetables can not be well maintained,so there is an urgent need to improve the operational efficiency of the green supply chain of fruits and vegetables.The operational efficiency of the green supply chain of fruits and vegetables is affected by many factors,and the most important factor is the incomplete consistency between the individual interests of supply chain members and the overall interests of supply chain.Therefore,the key driving force to improve the efficiency of green supply chain of fruits and vegetables is to build the scientific and rational collaborative decision-making mechanism of supply chain,in order to solve the problems concerning the green supply chain of fruits and vegetables,such as risk sharing,cost control and revenue allocation,thereby achieving the coordinated development of the green supply chain of fruits and vegetables.

  1. Invasion of Nostocales (cyanobacteria to subtropical and temperate freshwater lakes – Physiological, regional and global driving forces

    Directory of Open Access Journals (Sweden)

    Assaf eSukenik

    2012-03-01

    Full Text Available Similarly to the increased number of studies on invasive plants and animals in terrestrial and aquatic ecosystems, many reports were recently published on the invasion of Nostocales (cyanobacteria to freshwater environments worldwide. Invasion and proliferation of Nostocales in new habitats have the potential to significantly alter the structure of native community and to modify ecosystem functioning. But most importantly, they influence the water quality due to a variety of toxic compounds that some species produce. Therefore a special attention was given to the invasion and persistence of toxic cyanobacteria in many aquatic ecosystems. Here we summarize the currently published records on the invasion of two Nostocales genera, Cylindrospermopsis and Aphanizomenon, to lakes and water reservoirs in subtropical and temperate zones. These invading species possess traits thought to be common to many invasive organisms: high growth rate, high resource utilization efficiency and overall superior competitive abilities over native species when local conditions vary. Assuming that dispersion routes of cyanobacteria have not been changed much in recent decades, their recent establishment and proliferation in new habitats indicate changes in the environment under which they can exploit their physiological advantage over the native phytoplankton population. In many cases global warming was identified as the major driving force for the invasion of Nostocales. Due to this uncontrollable trend, invasive Nostocales species are expected to maintain their presence in new habitats and further expand to new environments. In other cases regional changes in nutrient loads and in biotic conditions were attributed to the invasion events

  2. The Driving Forces for the Practice of Strategic Planning in SMEs: Evidence from Harare Metropolitan Province, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Maxwell Sandada

    2016-08-01

    Full Text Available Despite Zimbabwe sharing with the rest of the world, the notion that SMEs are the impeccable engines to economic revival, growth and development, many of the nation`s SMEs are plagued with high failure rates. Previous studies carried out in most foreign countries suggested that the high failure rate of SMEs was attributable to lack of strategic planning among a host of other factors. Against this backdrop, the purpose of this study was to examine the driving forces for the practice of strategic planning in SMEs. A quantitative cross sectional study was conducted among active SMEs who are registered with the Ministry of Small and Medium Enterprises and Cooperative Development in Zimbabwe. The study revealed that globalisation, business ownership motivations, environmental dynamism and innovation & technological advancement have a positive and statistically significant influence on the adoption or practice of strategic planning among SMEs. The study has important implications for the practice and implementation of strategic planning among SMEs especially in the context of a developing country such as Zimbabwe.

  3. A microfluidic device based on gravity and electric force driving for flow cytometry and fluorescence activated cell sorting.

    Science.gov (United States)

    Yao, Bo; Luo, Guo-an; Feng, Xue; Wang, Wei; Chen, Ling-xin; Wang, Yi-ming

    2004-12-01

    A novel method based on gravity and electric force driving of cells was developed for flow cytometry and fluorescence activated cell sorting in a microfluidic chip system. In the experiments cells flowed spontaneously under their own gravity in a upright microchip, passed through the detection region and then entered into the sorting electric field one by one at an average velocity of 0.55 mm s(-1) and were fluorescence activated cell sorted (FACS) by a switch-off activation program. In order to study the dynamical and kinematic characteristics of single cells in gravity and electric field of microchannels a physical and numerical module based on Newton's Law of motion was established and optimized. Hydroxylpropylmethyl cellulose (HPMC) was used to minimize cell assembling, sedimentation and adsorption to microchannels. This system was applied to estimate the necrotic and apoptotic effects of ultraviolet (UV) light on HeLa cells by exposing them to UV radiation for 10, 20 or 40 min and the results showed that UV radiation induced membrane damage contributed to the apoptosis and necrosis of HeLa cells.

  4. Driving forces in energy-related CO2 emissions in south and east coastal China: commonality and variations

    Science.gov (United States)

    Gao, C.; Liu, Y.; Jin, J.; Wei, T.

    2015-12-01

    East and south coastal China contributes to respectively about 30% and 8% of CO2 emissions in China and the world, and therefore play a critical role in achieving the national goal of emission reduction to mitigate the global warming. It also serves as a benchmark for the less developed regions of China, in terms of achieving the developed world's human development standard under lower per capita emissions. We analyze the driving forces of emissions in this region and their provincial characteristics by applying the Logarithmic Mean Divisia Index method. Our findings show that emissions have been doubled during the period from 2000 to 2012, along with three and two folds increase in economy and energy consumption, respectively. This suggests a persistent lock between economic growth and emissions, even in this socioeconomically advanced region in China. Provincial difference in annual emission growth reveals three distinguished low-carbon developmental stages, owning mainly to the effectiveness of energy efficiency in reducing emission growth. This may explain why previous climate policies have aimed to reduce carbon intensity. These results indicate that targeted measures on enhancing energy efficiency in the short term and de-carbonization of both the economic and energy structure in the long term can lower the emission growth more effectively and efficiently. They also suggest that factor-driven emission reduction strategies and policies are needed in the geographically and socioeconomically similar regions.

  5. Entropy-enthalpy transduction caused by conformational shifts can obscure the forces driving protein-ligand binding.

    Science.gov (United States)

    Fenley, Andrew T; Muddana, Hari S; Gilson, Michael K

    2012-12-04

    Molecular dynamics simulations of unprecedented duration now can provide new insights into biomolecular mechanisms. Analysis of a 1-ms molecular dynamics simulation of the small protein bovine pancreatic trypsin inhibitor reveals that its main conformations have different thermodynamic profiles and that perturbation of a single geometric variable, such as a torsion angle or interresidue distance, can select for occupancy of one or another conformational state. These results establish the basis for a mechanism that we term entropy-enthalpy transduction (EET), in which the thermodynamic character of a local perturbation, such as enthalpic binding of a small molecule, is camouflaged by the thermodynamics of a global conformational change induced by the perturbation, such as a switch into a high-entropy conformational state. It is noted that EET could occur in many systems, making measured entropies and enthalpies of folding and binding unreliable indicators of actual thermodynamic driving forces. The same mechanism might also account for the high experimental variance of measured enthalpies and entropies relative to free energies in some calorimetric studies. Finally, EET may be the physical mechanism underlying many cases of entropy-enthalpy compensation.

  6. [Landscape pattern change of Dongzhai Harbour mangrove, South China analyzed with a patch-based method and its driving forces].

    Science.gov (United States)

    Huang, Xing; Xin, Kun; Li, Xiu-zhen; Wang, Xue-ping; Ren, Lin-jing; Li, Xi-zhi; Yan, Zhong-zheng

    2015-05-01

    According to the interpreted results of three satellite images of Dongzhai Harbour obtained in 1988, 1998 and 2009, the changes of landscape pattern and the differences of its driving forces of mangrove forest in Dongzhai Harbour were analyzed with a patch-based method on spatial distribution dynamics. The results showed that the areas of mangrove forest in 1988, 1998 and 2009 were 1809.4, 1738.7 and 1608.2 hm2 respectively, which presented a trend of decrease with enhanced degree of landscape fragmentation. The transformations among different landscape types indicated that the mangrove, agricultural land and forest land were mainly changed into built-up land and aquaculture pond. The statistical results obtained from three different methods, i.e., accumulative counting, percentage counting and main transformation route counting, showed that natural factors were the main reason for the changes of patch number, responsible for 58.6%, 72.2% and 72.1% of patch number change, respectively, while the percentages of patch area change induced by human activities were 70.4%, 70.3% and 76.4%, respectively, indicating that human activities were the primary factors of the change of patch areas.

  7. Characteristics of secondary migration driving force of tight oil and its geologic effect: a case study of Jurassic in Central Sichuan Basin

    Science.gov (United States)

    Pang, Zhenglian; Tao, Shizhen; Zhang, Bin; Wu, Songtao; Yang, Jiajing; Chen, Ruiyin

    2017-04-01

    As the rising of its production, tight oil is becoming more and more important. Much research has been done about it. Some articles mention that buoyancy is ineffective for tight oil secondary migration, and abnormal pressure is the alternative. Others believe that overpressure caused hydrocarbon generation is the very force. Though opinions have been given, there are two inadequacies. Firstly, the points are lack of sufficient evidences. Mostly, they are only one or two sentences in the papers. Secondly, geologic effect of the change of driving force hasn't been discussed. In this context, analog experiments, physical property testing, mercury injection, and oil/source comparison were utilized to study 3 issues: origin and value of tight oil secondary migration resistance, values and effectiveness of different potential driving forces, and geologic effect of tight oil secondary migration driving force. Firstly, resistance values of tight reservoir were detected by analog experiments. The value of tight limestone is 15.8MPa, while tight sandstone is 10.7MPa. Tiny size of pores and throats in tight reservoir is the main reason causing huge resistances. Over 90% of pores and throats in tight reservoir are smaller than 1μm. They form huge capillary force when oil migrating through them. Secondly, maximum of buoyancy in study area was confirmed, 0.09MPa, too small to overcome the resistances. Meanwhile, production data suggests that tight oil distribution pattern is not controlled by buoyancy. Conversely, analog experiment proves that overpressure caused by hydrocarbon generation can reach 38MPa, large enough to be the driving force. This idea is also supported by positive correlation between output and source rock formation pressure. Thirdly, is the geologic effect of tight oil secondary migration resistance and driving force. Tight oil can migrate only as non-darcy flow due to huge resistances according to percolation experiments. It needs to overcome the starting

  8. The Driving Force

    Institute of Scientific and Technical Information of China (English)

    Liu Zhiyang

    2011-01-01

    There is a popular aphorism in China,"The third-class enterprise produces products,the second-class creates brands,and the first-class develops standards".This shows that Standardization has been heavily emphasized in China.As the super large govemment-owned enterprise,the State Grid Corporation of China (SGCC) bears the mission of providing public energy and implementing social responsibility with the construction and operation of national power grid as its core business,SGCC has been always paying great attention to the standardization work since its establishment,and made outstanding achievements in both standardization and corporate development,ranked 7th in the FORTUNE GLOBAL 500 in 2011.

  9. Land use and land cover change and its driving forces in Maqu County, China in the past 25 years

    Institute of Scientific and Technical Information of China (English)

    JunFeng Lu; ZhiBao Dong; GuangYin Hu; WenJin Li; WanYin Luo; MingLiang Tan

    2016-01-01

    Maqu County is located in the northeast Qinghai-Tibetan Plateau, and it is the main watershed for the Yellow River. The ecosystem there is extremely vulnerable and sensitive to climate change and human activities, which have caused significant deterioration of the eco-environment in this region. In order to restore the ecological environment, a government project to restore the grazing areas to grassland was implemented in Maqu County in early 2004. This study evaluates the effects of that restoration project on land use and land cover change (LUCC), and explores the driving forces of LUCC in Maqu County. In the study we used Landsat images obtained in 1989, 2004, 2009, and 2014 to establish databases of land use and land cover. Then we derived LUCC information by overlaying these layers using GIS software. Finally, we analyzed the main forces responsible for LUCC. The results showed that forests, high-coverage grasslands, and marshes experienced the most signif-icant decreases during 1989–2004, by 882.8 ha, 35,250.4 ha, and 2,753.4 ha, respectively. However, moderate- and low-coverage grasslands and sand lands showed the opposite trend, increasing by 12,529.7 ha, 25,491.0 ha, and 577.5 ha, respectively. LUCC in 2004–2009 showed that ecological degradation slowed compared with 1989−2004. During 2009–2014, high- and moderate-coverage grasslands increased obviously, but low-coverage grasslands, marshes, unused lands, sand lands, and water areas showed the opposite trend. These results suggested that the degradation of the eco-environment was obvious before 2009, showing a decrease in the forests, grasslands, and water areas, and an increase in unused lands. The ecological degradation was reversed after 2009, as was mainly evidenced by increases in high-and mod-erate-coverage grasslands, and the shrinkage rate of marshes decreased obviously. These results showed that the project of restoring grazing lands to grassland had a positive effect on the LUCC. Other

  10. Comparison of the driving forces of spring phenology among savanna landscapes by including combined spatial and temporal heterogeneity.

    Science.gov (United States)

    Zhu, Likai; Southworth, Jane; Meng, Jijun

    2015-10-01

    Understanding spatial and temporal dynamics of land surface phenology (LSP) and its driving forces are critical for providing information relevant to short- and long-term decision making, particularly as it relates to climate response planning. With the third generation Global Inventory Monitoring and Modeling System (GIMMS3g) Normalized Difference Vegetation Index (NDVI) data and environmental data from multiple sources, we investigated the spatio-temporal changes in the start of the growing season (SOS) in southern African savannas from 1982 through 2010 and determined its linkage to environmental factors using spatial panel data models. Overall, the SOS occurs earlier in the north compared to the south. This relates in part to the differences in ecosystems, with northern areas representing high rainfall and dense tree cover (mainly tree savannas), whereas the south has lower rainfall and sparse tree cover (mainly bush and grass savannas). From 1982 to 2010, an advanced trend was observed predominantly in the tree savanna areas of the north, whereas a delayed trend was chiefly found in the floodplain of the north and bush/grass savannas of the south. Different environmental drivers were detected within tree- and grass-dominated savannas, with a critical division being represented by the 800 mm isohyet. Our results supported the importance of water as a driver in this water-limited system, specifically preseason soil moisture, in determining the SOS in these water-limited, grass-dominated savannas. In addition, the research pointed to other, often overlooked, effects of preseason maximum and minimum temperatures on the SOS across the entire region. Higher preseason maximum temperatures led to an advance of the SOS, whereas the opposite effects of preseason minimum temperature were observed. With the rapid increase in global change research, this work will prove helpful for managing savanna landscapes and key to predicting how projected climate changes will affect

  11. Free energy partitioning analysis of the driving forces that determine ion density profiles near the water liquid-vapor interface.

    Science.gov (United States)

    Arslanargin, Ayse; Beck, Thomas L

    2012-03-14

    Free energy partitioning analysis is employed to explore the driving forces for ions interacting with the water liquid-vapor interface using recently optimized point charge models for the ions and SPC/E water. The Na(+) and I(-) ions are examined as an example kosmotrope/chaotrope pair. The absolute hydration free energy is partitioned into cavity formation, attractive van der Waals, local electrostatic, and far-field electrostatic contributions. We first compute the bulk hydration free energy of the ions, followed by the free energy to insert the ions at the center of a water slab. Shifts of the ion free energies occur in the slab geometry consistent with the SPC/E surface potential of the water liquid-vapor interface. Then the free energy profiles are examined for ion passage from the slab center to the dividing surface. The profiles show that, for the large chaotropic I(-) ion, the relatively flat total free energy profile results from the near cancellation of several large contributions. The far-field electrostatic part of the free energy, largely due to the water liquid-vapor interface potential, has an important effect on ion distributions near the surface in the classical model. We conclude, however, that the individual forms of the local and far-field electrostatic contributions are expected to be model dependent when comparing classical and quantum results. The substantial attractive cavity free energy contribution for the larger I(-) ion suggests that there is a hydrophobic component important for chaotropic ion interactions with the interface.

  12. The CSIRO Mk3L climate system model version 1.0 – Part 2: Response to external forcings

    Directory of Open Access Journals (Sweden)

    S. J. Phipps

    2012-05-01

    Full Text Available The CSIRO Mk3L climate system model is a coupled general circulation model, designed primarily for millennial-scale climate simulation and palaeoclimate research. Mk3L includes components which describe the atmosphere, ocean, sea ice and land surface, and combines computational efficiency with a stable and realistic control climatology. It is freely available to the research community. This paper evaluates the response of the model to external forcings which correspond to past and future changes in the climate system.

    A simulation of the mid-Holocene climate is performed, in which changes in the seasonal and meridional distribution of incoming solar radiation are imposed. Mk3L correctly simulates increased summer temperatures at northern mid-latitudes and cooling in the tropics. However, it is unable to capture some of the regional-scale features of the mid-Holocene climate, with the precipitation over Northern Africa being deficient. The model simulates a reduction of between 7 and 15% in the amplitude of El Niño-Southern Oscillation, a smaller decrease than that implied by the palaeoclimate record. However, the realism of the simulated ENSO is limited by the model's relatively coarse spatial resolution.

    Transient simulations of the late Holocene climate are then performed. The evolving distribution of insolation is imposed, and an acceleration technique is applied and assessed. The model successfully captures the temperature changes in each hemisphere and the upward trend in ENSO variability. However, the lack of a dynamic vegetation scheme does not allow it to simulate an abrupt desertification of the Sahara.

    To assess the response of Mk3L to other forcings, transient simulations of the last millennium are performed. Changes in solar irradiance, atmospheric greenhouse gas concentrations and volcanic emissions are applied to the model. The model is again broadly successful at simulating larger-scale changes in the

  13. 三维滑坡推力计算方法探讨%CALCULATION METOD FOR DRIVING FORCE OF THREE-DIMENSIONAL LANDSLIDES

    Institute of Scientific and Technical Information of China (English)

    张常亮; 李同录; 李萍

    2011-01-01

    The common two-dimensional(2D)methods for the driving forces of landslides don't consider the lateral variation and confinements,which can make the stabilization design un-precisely. Three-dimensional(3D) method can reflect the spatialdistribution of the driving force of landslide. So it can resolve the problem of 2D methods. This paper provides a general formula for calculating the driving force of 3D landslide. It is based on the method of the general form of 3D equilibrium proposed by the authors. The paper presents case studies and a comparison between the 2D and 3D methods. Then,it obtains a distribution function of the lateral variation. This function reflects the spatial distribution of the driving force of 3D landslides,and makes slope stabilization design more reasonable.%常规二维滑坡推力计算没有考虑其横向变化,导致设计过于保守,三维推力计算方法的提出则能体现滑坡推力的空间分布,解决二维存在的问题.本文在三维极限平衡法统一模型的基础上,建立了求解三维滑坡推力的统一公式.利用实例,通过二维推力计算与三维计算结果的对比分析,获得三维推力的横向分布函数,有效反映出三维滑坡推力的空间分布状态,所得三维滑坡推力应用于设计更合理.

  14. [Spatio-temporal change of sand-fixing function and its driving forces in desertification control ecological function area of Hunshandake, China].

    Science.gov (United States)

    Shen, Lu; Tian, Mei-rong; Gao, Ji-xi; Qian, Jin-ping

    2016-01-01

    Soil erosion is an important ecological and environmental problem in Hunshandake Desert, and the sand-fixing function determines the degree of ecological security in the entire region. In order to clarify the situation of windbreak and sand fixation in Hunshandake area, and to guide the prevention and treatment of desertification on regional scale, based on the meteorological and remote sensing data, this paper quantitatively analyzed the temporal and spatial pattern of windbreak and sand fixation ability between 2000-2010 by the revised wind erosion equation (RWEQ) model, meanwhile, the driving forces for each county ( or banner) in the functional zone were analyzed with the method of principal component analysis. The results showed that there was a fluctuation of the sand fixing capacity in Hunshandake over time, generally rendering a decline trend. The coniferous forest and grassland had strong windbreak and sand fixation capacity in unit area among the various land categories. In terms of spatial distribution, the windbreak and sand fixation function in western and southeastern region was weak and needed to be strengthened with ecological restoration efforts. Through the study of the social driving forces of each administrative region in the function zone, there were 3 main social driving forces of soil erosion in the administrative functions: the intensity of input-output, the level of economic development and the level of agriculture-husbandry development.

  15. Force

    CERN Document Server

    Graybill, George

    2007-01-01

    Forces are at work all around us. Discover what a force is, and different kinds of forces that work on contact and at a distance. We use simple language and vocabulary to make this invisible world easy for students to ""see"" and understand. Examine how forces ""add up"" to create the total force on an object, and reinforce concepts and extend learning with sample problems.

  16. 10-15 years of GST monitoring over mountain permafrost in Switzerland: Indicators for driving forces for permafrost evolution

    Science.gov (United States)

    Staub, Benno; Delaloye, Reynald; Hilbich, Christin; Lambiel, Christophe; Nötzli, Jeannette; Völksch, Ingo

    2013-04-01

    Ground Surface Temperatures (GST) are mainly controlled by atmospheric factors and topographical effects and represent an important standard element within the operational permafrost monitoring network PERMOS in Switzerland. Due to its shape, position and extent the Alpine arc is influenced by prevailing winds from several directions provoking a complex and highly variable pattern of precipitation in different regions of Switzerland with a general trend to a more continental climate in some inner-alpine valleys. The lower boundary for the occurrence of mountain permafrost in the Swiss Alps is located at about 2500 m asl., close to the free atmosphere where air temperatures are almost homogenous in all regions, but precipitation usually shows large regional differences regarding timing and quantity depending on the meteorological conditions. At the elevation range of mountain permafrost the ground surface remains snow-free only for about 4-5 months (between June and November) with a high temporal and spatial variability, while over the rest of the year it stays well shielded from the atmosphere (due to the high surface albedo and emissivity and low thermal conductivity of snow). Therefore, the influence of the atmosphere at this boundary layer on the ground thermal regime is well reflected by GST measurements on a very local, site-specific scale. Relative values like GST anomalies can serve as indicators describing processes of energy and heat transfer at the ground surface in a semi-quantitative way. This information is used in a signal-response analysis integrating GST with other permafrost monitoring elements that represent the permafrost response to external effects (e.g. relative changes in borehole temperatures, apparent electrical resistivities or rock glacier creep rates). To identify and quantify the dominant processes and factors controlling the response of Alpine permafrost to external forces, special consideration is devoted to the characteristics of

  17. STUDY OF STATIC AND DYNAMIC STABILITY OF THIN-WALLED BARS EXCITED BY PERIODICAL AXIAL EXTERNAL FORCES.

    Directory of Open Access Journals (Sweden)

    Minodora Maria PASĂRE

    2010-10-01

    Full Text Available In these paper, starting from the relations for the displacements and spinning the transversal section of a bar with thin walls of sections opened expressed by the corresponding influence functions and introducing the components of the exterior forces distributed and the moments of the exterior forces distributed due to the inertia forces, the exciting axial forces together with the following effect of these and of the reaction forces of the elastic environment for leaning it may reach to the system of the equations of parametric vibrations under the form of three integral equation These equations may serve for the study of vibrations of the bars, to study the static stability and to study the dynamic stability

  18. Gear bearing drive

    Science.gov (United States)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  19. Effect of dust ion collision on dust ion acoustic waves in the framework of damped Zakharov-Kuznetsov equation in presence of external periodic force

    Science.gov (United States)

    Kanti Das, Tushar; Ali, Rustam; Chatterjee, Prasanta

    2017-10-01

    The dynamics of dust ion acoustic waves (DIAWs) is investigated in a magnetized dusty plasma whose constituents are cold ions, superthermal electrons, and dust particles in the framework of a damped Zakharov-Kuznetsov (dZK) equation in the presence of externally applied periodic force. The dZK equation is derived employing the standard reductive perturbation technique. The effect of dust ion collision on the quasiperiodic and chaotic motion of dust ion acoustic waves is discussed. It is observed that the collision frequency νid 0 plays the role of a switching parameter from the quasiperiodic route to chaos for the DIAWs.

  20. Effect of pinning and driving force on the metastability effects in weakly pinned superconductors and the determination of spinodal line pertaining to order-disorder transition

    Indian Academy of Sciences (India)

    A D Thakur; S S Banerjee; M J Higgins; S Ramakrishnan; A K Grover

    2006-01-01

    We explore the effect of varying drive on metastability features exhibited by the vortex matter in single crystals of 2H-NbSe2 and CeRu2 with varying degree of random pinning. The metastable nature of vortex matter is reflected in the path dependence of the critical current density, which in turn is probed in a contact-less way via AC-susceptibility measurements. The sinusoidal AC magnetic field applied during AC susceptibility measurements appears to generate a driving force on the vortex matter. In a nascent pinned single crystal of 2H-NbSe2, where the peak effect (PE) pertaining to the order-disorder phenomenon is a sharp first-order-like transition, the supercooling feature below the peak temperature is easily wiped out by the reorganization caused by the AC driving force. In this paper, we elucidate the interplay between the drive and the pinning which can conspire to make the path-dependent AC-susceptibility response of different metastable vortex states appear identical. An optimal balance between the pinning and driving force is needed to view the metastability effects in typically weakly pinned specimen of low temperature superconductors. As one uses samples with larger pinning in order to differentiate the response of different metastable vortex states, one encounters a new phenomenon, viz., the second magnetization peak (SMP) anomaly prior to the PE. Supercooling/superheating can occur across both the PE and the SMP anomalies and both of these are known to display non-linear characteristics as well. Interplay between the path dependence in the critical current density and the non-linearity in the electromagnetic response determine the metastability effects seen in the first and the third harmonic response of the AC susceptibility across the temperature regions of the SMP and the PE. The limiting temperature above which metastability effects cease can be conveniently located in the third harmonic data, and the observed behavior can be rationalized within

  1. Tuning a PD Controller Based on an SVR for the Control of a Biped Robot Subject to External Forces and Slope Variation

    Directory of Open Access Journals (Sweden)

    João P. Ferreira

    2014-03-01

    The ZMP is calculated by reading four force sensors placed under each of the robot’s feet. The gait implemented in this biped is similar to a human gait, which is acquired and adapted to the robot’s size. The main contribution of this paper is the fine-tuning of the ZMP controller based on the SVR. To implement and test this, the biped robot was subjected to external forces and slope variation. Some experiments are presented and the results show that the implemented gait combined with the correct tuning of the SVR controller is appropriate for use with this biped robot. The SVR controller runs at 0.2 ms, which is about 50 times faster than a corresponding first- order TSK neural-fuzzy network.

  2. Research on Driving Force in Rural Land Capitalization%农村土地资产化的驱动力研究

    Institute of Scientific and Technical Information of China (English)

    薛红霞

    2012-01-01

    Studying the driving force in rural land capitalization is the foundation to build and perfect the mechanism of rural land capitalization. In order to solve such problems as the vacancy of the main land ownership and the limitation of land disposition, which prevent the process of rural land capitalization this paper analyzes the driving forces in rural land capitalization and their deficiencies, using the methods of empirical and normative analysis, qualitative and quantitative analysis, comparative and systems analysis, with the following conclusions; the key to building the mechanism of rural land capitalization is to enhance the driving force, improve the market environment, land management system and the government's macro-control capacity, and reduce or gradually eliminate the resistance.%研究农村土地资产化的驱动力是构建和完善农村土地资产化机制的基础.为解决土地所有权主体虚置及土地处分权受限等阻碍农村土地资产化进程的问题,采用实证分析与规范分析相结合、定性分析与定量分析相结合、比较分析法和系统分析法分析农村土地资产化的驱动力及其缺陷,得出结论是构建农村土地资产化机制的核心在于增强驱动力,完善市场环境、土地制度和政府宏观管理调控能力,减少或逐步消除土地资产化的推阻力.

  3. The effect of electric field geometry on the performance of electromembrane extraction systems: Footprints of a third driving force along with migration and diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Moazami, Hamid Reza [School of Physics and Accelerators, NSTRI, P. O. Box, 11365-8486, Tehran (Iran, Islamic Republic of); Hosseiny Davarani, Saied Saeed, E-mail: ss-hosseiny@sbu.ac.ir [Faculty of Chemistry, Shahid Beheshti University, G. C., 1983963113, Evin, Tehran (Iran, Islamic Republic of); Mohammadi, Jamil; Nojavan, Saeed [Faculty of Chemistry, Shahid Beheshti University, G. C., 1983963113, Evin, Tehran (Iran, Islamic Republic of); Abrari, Masoud [Laser and Plasma Research Institute, Shahid Beheshti University, G. C., 1983963113, Evin, Tehran (Iran, Islamic Republic of)

    2015-09-03

    The distribution of electric field vectors was first calculated for electromembrane extraction (EME) systems in classical and cylindrical electrode geometries. The results showed that supported liquid membrane (SLM) has a general field amplifying effect due to its lower dielectric constant in comparison with aqueous donor/acceptor solutions. The calculated norms of the electric field vector showed that a DC voltage of 50 V can create huge electric field strengths up to 64 kV m{sup −1} and 111 kV m{sup −1} in classical and cylindrical geometries respectively. In both cases, the electric field strength reached its peak value on the inner wall of the SLM. In the case of classical geometry, the field strength was a function of the polar position of the SLM whereas the field strength in cylindrical geometry was angularly uniform. In order to investigate the effect of the electrode geometry on the performance of real EME systems, the analysis was carried out in three different geometries including classical, helical and cylindrical arrangements using naproxen and sodium diclofenac as the model analytes. Despite higher field strength and extended cross sectional area, the helical and cylindrical geometries gave lower recoveries with respect to the classical EME. The observed decline of the signal was proved to be against the relations governing migration and diffusion processes, which means that a third driving force is involved in EME. The third driving force is the interaction between the radially inhomogeneous electric field and the analyte in its neutral form. - Highlights: • Electric field vectors have been calculated in EME systems. • A new driving force has been proposed in EME systems. • EME can be theoretically applied to nonionic polarizable analytes.

  4. Using geoinformatics and cultural anthropology to identify links between land change, driving forces and actors in the Okavango catchment

    Science.gov (United States)

    Röder, Achim; Stellmes, Marion; Pröpper, Michael; Schneibel, Anne

    2015-04-01

    intensive uses, although the same processes are likely to occur in parts of the Okavango region in the future. Literature: Banwart, S. (2011). "Save our soils." Nature 474: 151-152. Bürgi, M., A. M. Hersperger, et al. (2004). "Driving forces of landscape change - current and new directions." Landscape Ecology 19: 857-868. Butchart, S. H. M., M. Walpole, et al. (2010). "Global Biodiversity: Indicators of Recent Declines." Science 328(5982): 1164-1168. Ellis, E. C. and N. Ramankutty (2008). "Putting people in the map: anthropogenic biomes of the world." Frontiers in Ecology and the Environment 6(8): 439-447. Foley, J. A., R. Defries, et al. (2005). "Global consequences of land use." Science 309(5734): 570-574. Geist, H. J. and E. F. Lambin (2002). "Proximate causes and underlying driving forces of tropical deforestation." BioScience 52(2): 143-150. Haub, C. (2012) World Population Data Sheet. World Population Hein, L., K. van Koppen, et al. (2006). "Spatial scales, stakeholders and the valuation of ecosystem services." Ecological Economics 57: 209-228. Hersperger, A. M., M.-P. Gennaio, et al. (2010). "Linking land change with driving forces and actors: four conceptual models." Ecology and Society 15(4): 1-17. Huang, C., L. S. Davis, et al. (2002). "An assessment of support vector machines for land cover classification." International Journal of Remote Sensing 23(4): 725-749. IPCC (2013). Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. T. F. Stocker, G. Qin, G.-K. Plattneret al. Cambridge, Cambridge University Press. Jönsson, P. and L. Eklundh (2004). "TIMESAT - a program for analysing time-series of satellite sensor data." Computers and Geosciences 30(833-845). Kowalski, B., N. Azebaze, et al. (2013). "Mashare - The People." Biodiversity & Ecology 5: 121-128. Lal, R. (2013). "Climate-strategic agriculture and the water-soil-waste nexus." Journal of Plant

  5. The application of an external wrist extension force reduces electromyographic activity of wrist extensor muscles during gripping.

    NARCIS (Netherlands)

    Elk, N. van; Faes, M.C.; Degens, H.; Kooloos, J.G.M.; Lint, J.A. de; Hopman, M.T.E.

    2004-01-01

    STUDY DESIGN: Experimental repeated-measures study. OBJECTIVE: To investigate the effect of different extension forces applied to the palm of the hand on electromyographic (EMG) activity of the wrist extensor muscles during hand gripping. BACKGROUND: Lateral epicondylitis is usually caused by repeti

  6. DYNAMIC MODEL OF CROP GROWTH SYSTEM AND NUMERICAL SIMULATION OF CROP GROWTH PROCESS UNDER THE MULTI-ENVIRONMENT EXTERNAL FORCE ACTION

    Institute of Scientific and Technical Information of China (English)

    李自珍; 王万雄; 徐彩琳

    2003-01-01

    According to the biomechanic theory and method, the dynamic mechanism of crop growth under the external force action of multi-environment factors (light, temperature, soil and nutrients etc.) was comprehensively explored. Continuous-time Markov (CTM) approach was adopted to build the dynamic model of the crop growth system and the simulated numerical method. The growth rate responses to the variation of the external force and the change of biomass saturation value were studied. The crop grew in the semiarid area was taken as an example to carry out the numerical simulation analysis, therefore the results provide the quantity basis for the field management. Comparing the dynamic model with the other plant growth model, the superiority of the former is that it displays multi-dimension of resource utilization by means of combining macroscopic with microcosmic and reveals the process of resource transition. The simulation method of crop growth system is advanced and manipulated. A real simulation result is well identical with field observational results.

  7. Priming Silicic Giant Magma Bodies: Finding Evidence for Internal Forcing Versus External Triggering of Supereruptions by Phase Equilibria Modeling.

    Science.gov (United States)

    Tramontano, S.; Gualda, G. A. R.; Ghiorso, M. S.; Kennedy, B.

    2015-12-01

    It is important to understand what triggers silicic eruptions because of the implications for modern-day systems. The goal of this project is to use phase equilibria modeling (i.e. rhyolite-MELTS) to determine to what extent magmas within the crust are induced to erupt due to external triggers (e.g. earthquakes; new magma injection; neighboring eruptions) and to what extent they naturally evolve to a point where eruption is inevitable (e.g. by fluid exsolution and decrease in magma strength and density). Whole-rock compositions from four rhyolite tuffs across the globe associated with large or supereruptions (Mamaku Tuff, New Zealand; Peach Spring Tuff, SW USA; early and late-erupted Bishop Tuff, California; and Toba Tuff, Indonesia) are studied using rhyolite-MELTS modeling. Key physical properties of magma are strongly affected by the initial volatile content due to fluid exsolution. By running simulations with varying water contents, we can track the evolution of fluid exsolution during crystallization. Isobaric (constrained temperature change at constant pressure) and isochoric (constrained temperature change at constant volume) models were run for the four compositions. In constrained-pressure scenarios, fluid is free to exsolve as crystallization proceeds, and the total system volume can increase or decrease accordingly; this would require deformation of the surrounding crust to accommodate the magma volume change. In constrained-volume scenarios, bubble exsolution is limited to the volume change due to crystallization; in this case, pressure can decrease or increase (if bubbles are absent or present). For fixed-pressure scenarios, fluid exsolution is more extensive and leads to internal triggering, at least for fluid-saturated conditions; external triggering is more likely in fluid-undersaturated conditions. For fixed-volume scenarios, none of the systems cross a fragmentation threshold for the crystal contents typically observed in natural pumice. If

  8. Study on Farmland Use Change and Driving Force in the High and Cold Areas in Northwest Yunnan——A Case Study of Ninglang Yi Autonomous County

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    On the basis of overview of the study area,by analyzing the dynamic change of farmland in Ninglang County,we can find that the farmland area in this county tended to decrease from 1996 to 2008.According to the investigation data concerning land change provided by Bureau of Land and Resources in Ninglang County and socio-economic data provided by Bureau of Statistics in Ninglang County,we select 11 indices,such as total population,GDP,total output value of county and so on,coupled with SPSS statistical method,we adopt principal component analysis method to analyze driving force factors of farmland use change in the high and cold areas in Northwest Yunnan.The results show that the two factors of economic development and population growth are the dominant driving factors impacting farmland use change,and the policy factors,such as "returning farmland to forests",are also the important driving factors impacting Ninglang County.

  9. Driving force-dependent block by internal Ba(2+) on the Kir2.1 channel: Mechanistic insight into inward rectification.

    Science.gov (United States)

    Hsieh, Chi-Pan; Kuo, Chung-Chin; Huang, Chiung-Wei

    2015-07-01

    The Kir2.1 channel is characterized by strong inward rectification; however, the mechanism of the steep voltage dependence near the equilibrium potential remains to be investigated. Here, we studied the internal Ba(2+) block of the Kir2.1 channel expressed in Xenopus oocytes. We showed that the driving force and thus the K(+) ion flux significantly influenced the apparent affinity of the block by internal Ba(2+). Kinetic analysis revealed that the binding rate shifted with the driving force and changed steeply near the equilibrium point, either in the presence or absence of the transmembrane electrical field. The unbinding rate was determined by the intrinsic affinity of the site. Mutagenesis studies revealed that the high-affinity binding site for Ba(2+) was located near T141 at the internal entrance of the selectivity filter. The steep change of the blocking affinity near the equilibrium potential may result from the flux-coupling effect in the single-file, multi-ion cytoplasmic pore.

  10. Driving Forces of Dynamic Changes in Soil Erosion in the Dahei Mountain Ecological Restoration Area of Northern China Based on GIS and RS.

    Science.gov (United States)

    Li, Xiao; Niu, Xiang; Wang, Bing; Gao, Peng; Liu, Yu

    2016-01-01

    Dynamic change in soil erosion is an important focus of regional ecological restoration research. Here, the dynamic changes of soil erosion and its driving forces in the Dahei Mountain ecological restoration area of northern China were analyzed by LANDSAT TM remote sensing captured via geographic information system (GIS) technologies during three typical periods in 2004, 2008 and 2013. The results showed the following: (1) a decrease in intensive erosion and moderate erosion areas, as well as an increase in light erosion areas, was observed during two periods: one from 2004 to 2008 and the other from 2008 to 2013. (2) Between 2004 and 2008, the variation in the range of slight erosion was the largest (24.28%), followed by light erosion and intensive erosion; between 2008 and 2013, the variation in the range of intensive erosion area was the largest (9.89%), followed by slight erosion and moderate erosion. (3) Socioeconomic impact, accompanied by natural environmental factors, was the main driving force underlying the change in soil erosion within the ecological restoration area. In particular, the socioeconomic factors of per capita forest area and land reclamation rate, as well as the natural environmental factor of terrain slope, significantly influenced soil erosion changes within the ecological restoration area.

  11. The effect of electric field geometry on the performance of electromembrane extraction systems: footprints of a third driving force along with migration and diffusion.

    Science.gov (United States)

    Moazami, Hamid Reza; Hosseiny Davarani, Saied Saeed; Mohammadi, Jamil; Nojavan, Saeed; Abrari, Masoud

    2015-09-03

    The distribution of electric field vectors was first calculated for electromembrane extraction (EME) systems in classical and cylindrical electrode geometries. The results showed that supported liquid membrane (SLM) has a general field amplifying effect due to its lower dielectric constant in comparison with aqueous donor/acceptor solutions. The calculated norms of the electric field vector showed that a DC voltage of 50 V can create huge electric field strengths up to 64 kV m(-1) and 111 kV m(-1) in classical and cylindrical geometries respectively. In both cases, the electric field strength reached its peak value on the inner wall of the SLM. In the case of classical geometry, the field strength was a function of the polar position of the SLM whereas the field strength in cylindrical geometry was angularly uniform. In order to investigate the effect of the electrode geometry on the performance of real EME systems, the analysis was carried out in three different geometries including classical, helical and cylindrical arrangements using naproxen and sodium diclofenac as the model analytes. Despite higher field strength and extended cross sectional area, the helical and cylindrical geometries gave lower recoveries with respect to the classical EME. The observed decline of the signal was proved to be against the relations governing migration and diffusion processes, which means that a third driving force is involved in EME. The third driving force is the interaction between the radially inhomogeneous electric field and the analyte in its neutral form.

  12. [Spatiotemporal patterns and driving forces of land use change in industrial relocation area: a case study of old industrial area in Tiexi of Shenyang, Northeast China].

    Science.gov (United States)

    Wang, Mei-Ling; Bing, Long-Fei; Xi, Feng-Ming; Wu, Rui; Geng, Yong

    2013-07-01

    Based on the QuickBird remote sensing images and with the support of GIS, this paper analyzed the spatiotemporal characteristics of land use change and its driving forces in old industrial area of Tiexi, Shenyang City of Liaoning Province in 2000-2010. During the study period, the industrial and mining warehouse land pattern had the greatest change, evolving from the historical pattern of residential land in the south and of industrial land in the north into residential land as the dominant land use pattern. In the last decade, the residential land area increased by 9%, mainly transferred from the industrial and mining warehouse land located in the north of Jianshe Road, while the industrial and mining warehouse land area decreased by 20%. The land areas for the commercial service and for the administrative and public services were increased by 1.3% and 3.1%, respectively. The land area for construction had a greater change, with an overall change rate being 76.9%. The land use change rate in 2000-2005 was greater than that in 2005-2010. National development strategies and policies, regional development planning, administrative reform, and industrial upgrading were the main driving forces of the land use change in old industrial area of Tiexi.

  13. Driving forces and barriers to improved energy performance of buildings: an analysis of energy performance of Swedish buildings, 2000-2006

    Energy Technology Data Exchange (ETDEWEB)

    Fuglseth, Bente Beckstroem

    2008-06-15

    The building sector is responsible for a substantial part of energy use and green house gas emissions in Europe. This report explores driving forces and barriers to improved energy performance of buildings, using the Swedish building sector as a case. The development of energy performance of buildings in Sweden from 2000 until 2006 is explored by applying a threefold understanding of energy performance of buildings: substitution from fossil fuels to renewable energy, conversion from electrical heating to thermal energy and reduction in energy demand. Three explanatory approaches are used to analyse driving forces and barriers to improved energy performance: the techno-economic approach stresses the physical aspects of infrastructure and technologies, the institutional approach emphasizes the role of institutional factors, while the regulative approach focuses on formal rules and laws. The study concludes that all factors have promoted substitution of fossil fuels with renewable energy, while they have prevented conversion from electrical heating to thermal energy and reduction in energy demand. (author). 95 refs

  14. On the Driving Forces of Magnetically Induced Martensitic Transformation in Directionally Solidified Polycrystalline Ni-Mn-In Meta-Magnetic Shape Memory Alloy with Structural Anisotropy

    Science.gov (United States)

    Hu, Qiaodan; Zhou, Zhenni; Yang, Liang; Huang, Yujin; Li, Jun; Li, Jianguo

    2017-08-01

    The magnetic anisotropy energy (MAE) in the ferromagnetic shape memory alloys (FSMAs) provides the driving forces to obtain large magnetic field induced strain (MFIS) by rearranging the martensitic variants. However, to date, no significant MAE was observed in the new class of Ni-Mn-Z (Z = In, Sn, Sb) metamagnetic shape memory alloys (MSMAs). Here, we report a significant magnetic anisotropy in Ni48Mn35In17 Heusler alloy with a [110]A fiber texture prepared by the directional solidification. In this case, when the applied magnetic field is along the [110]A direction, a larger magnetization change is obtained compared with that of the randomly oriented samples, which increases the driving forces for the magnetically induced martensitic transformation (MIMT). In contrast, along the [110]A direction, the magnetocaloric effect (MCE) is enhanced by 60 pct, the MFIS is improved by 20 pct, and the critical field for the MFIS is reduced by 0.5 T. Such a peculiar magnetic behavior could be well explained by a proposed model on the viewpoint of the transformation of ferromagnetic austenite phase. Furthermore, considering the thermodynamics aspects, we demonstrate that two main magnetic energies of the Zeeman energy and the MAE in the MSMAs assist each other to promote the MIMT, instead of opposing each other in the FSMAs. This discovery of the strong magnetic anisotropy in highly textured polycrystals provides a feasible route to enhance the MIMT, and new insights to design and prepare the Ni-Mn-based Heusler alloys for practical applications.

  15. A piezo motor based on a new principle with high output force, rigidity and integrity: The Tuna Drive

    Science.gov (United States)

    Liu, Xiaolong; Lu, Qingyou

    2012-11-01

    We present a linear piezoelectric motor as simple as one piezoelectric scanner tube (PST) spring-clamping a central shaft at both ends with roughly equal clamping forces. The clamping points are aligned with ±X electrodes at one end and ±Y electrodes at the other end. Thus, the ±X (or ±Y) push-pull motions of the PST can cause the push-pull motions of the clamping points on the shaft (called push-pull rubbing), which reduces the total dynamic friction force at one (or the other) end of the PST. This new piezo motor advances one step by fast push-pull rubbing at one end while slowly retracting the PST followed by fast push-pull rubbing at the other end while slowly elongating the PST. Apart from the obvious advantages of simplicity, rigidity, integrity, etc., we will also show that this motor can produce a large output force, which we believe is because of the huge drop of the clamping friction force when the push-pull rubbing occurs.

  16. The Contribution of Electric Force to Sintering Ⅱ.Natures of the Applied Electric Field for Driving lonic Diffusion

    Institute of Scientific and Technical Information of China (English)

    SHIShang-zhao

    1994-01-01

    Through discussion on the acting forces of the applied electric field on the ionic system,it was shown that a periordical field with both even and odd components is to be applied.The suitable wavelengty,the extent of the field intensity and electric potential and the application of the selected field were suggested.

  17. The short range anion-H interaction is the driving force for crystal formation of ions in water.

    Science.gov (United States)

    Alejandre, José; Chapela, Gustavo A; Bresme, Fernando; Hansen, Jean-Pierre

    2009-05-07

    The crystal formation of NaCl in water is studied by extensive molecular dynamics simulations. Ionic solutions at room temperature and various concentrations are studied using the SPC/E and TIP4P/2005 water models and seven force fields of NaCl. Most force fields of pure NaCl fail to reproduce the experimental density of the crystal, and in solution some favor dissociation at saturated conditions, while others favor crystal formation at low concentration. A new force field of NaCl is proposed, which reproduces the experimental phase diagram in the solid, liquid, and vapor regions. This force field overestimates the solubility of NaCl in water at saturation conditions when used with standard Lorentz-Berthelot combining rules for the ion-water pair potentials. It is shown that precipitation of ions is driven by the short range interaction between Cl-H pairs, a term which is generally missing in the simulation of ionic solutions. The effects of intramolecular flexibility of water on the solubility of NaCl ions are analyzed and is found to be small compared to rigid models. A flexible water model, extending the rigid SPC/E, is proposed, which incorporates Lennard-Jones interactions centered on the hydrogen atoms. This force field gives liquid-vapor coexisting densities and surface tensions in better agreement with experimental data than the rigid SPC/E model. The Cl-H, Na-O, and Cl-O pair distribution functions of the rigid and flexible models agree well with experiment. The predicted concentration dependence of the electric conductivity is in fair agreement with available experimental data.

  18. Analysis of Driving Force and Constraint Force of A 3UPU-Ⅰ Spatial Parallel Manipulator based on Force/Torque Balance Equations and CAD Variable Geometric Approach%基于力/矩平衡方程和变量几何法的3UPU-Ⅰ并联机构驱动力和约束力分析

    Institute of Scientific and Technical Information of China (English)

    岳秋琴

    2013-01-01

    提出利用力/力矩平衡方程CAD变量几何法求解并联机构各分支的驱动力和约束力.以3UPU-Ⅰ并联机构为例,首先利用求解驱动力和约束力的数学方程及计算机变量几何法,在3UPU-Ⅰ并联机构的模拟基础上构造该机构的三维F/T(力/力矩)模拟机构.然后从平衡方程中推演出一个力雅克比矩Gf,当改变驱动参数时,F/T模拟机构和Gf随之变化,驱动力和约束力自动求解和动态显示.%A CAD variation geometry approach and force/torque balance equations are proposed for solving driving force and constraint force of a 3-dof 3UPU-Ⅰ spatial parallel manipulator.Taking the 3UPU-Ⅰ spatial parallel manipulator for example,by using the mathematical equation and computer variation geometry method for solving driving force and constraint force,the 3D F/T (force/torque) simulation mechanism is constructed based on simulation mechanism of the parallel manipulator.A force Jacobian matrix equation Gf is derived from the balance equations of the manipulator,when the driving dimensions of active limbs parameter is modified,the configuration of the F/ T simulation mechanisms and Gf are varied correspondingly,and the driving and constraint force are solved automatically and visualized dynamically.

  19. Improving the Drive System of Permanent Magnet Linear Synchronous Motor Based on Direct Thrust Force Control Applying Space Vector Modulation

    Directory of Open Access Journals (Sweden)

    Mehdi Manoochehri

    2012-07-01

    Full Text Available Applying the direct thrust force control (DFC method in permanent magnet linear synchronous motor (PMLSM leads to some important problems. The most important disadvantages of applying this method are electromagnetic force and linkage flux big ripple and variable switching frequency. In this paper space vector modulation (SVM technique is applied for removing the disadvantages of classic DFC method. SVM technique makes the switching frequency constant and provides continues Voltage space compared with discrete space in classic method. Simulation results confirmed the theory. They show that combining the DFC method with SVM technique removes lots of the disadvantages of classic DFC method like big ripples and variable switching and remains the benefits of this method.

  20. “Coloniality of power” in East Central Europe: external penetration as internal force in post-socialist Hungarian politics

    Directory of Open Access Journals (Sweden)

    Agnes Gagyi

    2016-08-01

    Full Text Available Joining a series of analyses of effects of othering, orientalism, or coloniality in East Central Europe, the paper asks how long-term structural-ideological effects of global hierarchies, as reflected in post-colonial contexts by the term “coloniality of power,” can be conceptualized for East Central Europe. In a case study of political polarization in post-socialist Hungary,it examines the effects of global integration,  claiming that two dominant economic-political blocks formed along a division of vertical alliances related to integration with either Western or national capital. From those positions, they developed divergent political ideologies of development: modernization through Western integration, versus the protection of “national” wealth from Western capital and its local allies. While both propagated capitalist integration, they each needed to develop ideologies that appealed to electorates suffering the costs of integration. One framing of developmentalist emancipation promised Western modernity through rejection of popular, backward characteristics of the country, including nationalism. The other promised advancement in the global hierarchy through overcoming internal and external enemies of national development. These two, mutually reinforcing ideological positions, which I call“democratic antipopulism” and “antidemocratic populism,” denied the contradiction between elites’ and workers’ interest and perpetuated existing global hierarchies. Within the wider debate over cross-contextual applications of the notion of “coloniality of power,” and of emancipative efforts born from the “colonial wound,” the paper emphasizes the significance of the structural conditions, positions and alliances within which experiences of global domination are born and mobilized.

  1. Use of a device that applies external kneading-like force on the abdomen for treatment of constipation

    Institute of Scientific and Technical Information of China (English)

    Konstantinos Mimidis; David Galinsky; Efraim Rimon; Vassilios Papadopoulos; Yehuda Zicherman; Dimitrios Oreopoulos

    2005-01-01

    AIM: To evaluate the efficacy of a recently developed device that applies kneading-like motion on the abdomen in improving constipation in elderly long-term care patients.METHODS: Thirty constipated elderly patients were randomly selected from two nursing homes. They were instructed to use the device once daily for 20 min. Rate of bowel movements, volume and consistency of stool and the use of laxantia were all recorded during a 3-wk baseline period and for 12-wk treatment period. Colonic transit time (CTT) was measured in 13 patients by radiopaque markers during the baseline and at the end of treatment.RESULTS: Bowel movement rate (BM/week) increased from 1.4±0.4 BM/wk during baseline to 3.9±0.8 BM/wk during treatment (P<5.0×10-7). Stool amount that was "low" in 30 patients during baseline increased in 21 patients at the end of the study period (χ2 = 19.048-P =1.3×10-5). Stool consistency, that was "hard" in 25 patients and "soft" in 5 patients during baseline, ameliorated in 23 patients at the end of the study (only 2 patients referred "hard" stool) (χ2= 21.043-P = 4.0×10-6). The mean baseline CTT measured was 92.3±32.3 h at baseline and decreased to 49.4±31.3 h during the study period (P = 0.000208). No side effects were observed during the study period.CONCLUSION: External mechanical vibration of the abdomen reduced CTT and helped to relieve severe constipation in elderly constipated patients.

  2. Use of induced acceleration to quantify the (de)stabilization effect of external and internal forces on postural responses.

    Science.gov (United States)

    van Asseldonk, Edwin H F; Carpenter, Mark G; van der Helm, Frans C T; van der Kooij, Herman

    2007-12-01

    Due to the mechanical coupling between the body segments, it is impossible to see with the naked eye the causes of body movements and understand the interaction between movements of different body parts. The goal of this paper is to investigate the use of induced acceleration analysis to reveal the causes of body movements. We derive the analytical equations to calculate induced accelerations and evaluate its potential to study human postural responses to support-surface translations. We measured the kinematic and kinetic responses of a subject to sudden forward and backward translations of a moving platform. The kinematic and kinetics served as input to the induced acceleration analyses. The induced accelerations showed explicitly that the platform acceleration and deceleration contributed to the destabilization and restabilization of standing balance, respectively. Furthermore, the joint torques, coriolis and centrifugal forces caused by swinging of the arms, contributed positively to stabilization of the Center of Mass. It is concluded that induced acceleration analyses is a valuable tool in understanding balance responses to different kinds of perturbations and may help to identify the causes of movement in different pathologies.

  3. The endothermic ATP hydrolysis and crossbridge attachment steps drive the increase of force with temperature in isometric and shortening muscle.

    Science.gov (United States)

    Offer, Gerald; Ranatunga, K W

    2015-04-15

    The isometric tetanic tension of skeletal muscle increases with temperature because attached crossbridge states bearing a relatively low force convert to those bearing a higher force. It was previously proposed that the tension-generating step(s) in the crossbridge cycle was highly endothermic and was therefore itself directly targeted by changes in temperature. However, this did not explain why a rapid rise in temperature (a temperature jump) caused a much slower rate of rise of tension than a rapid length step. This led to suggestions that the step targeted by a temperature rise is not the tension-generating step but is an extra step in the attached pathway of the crossbridge cycle, perhaps located on a parallel pathway. This enigma has been a major obstacle to a full understanding of the operation of the crossbridge cycle. We have now used a previously developed mechano-kinetic model of the crossbridge cycle in frog muscle to simulate the temperature dependence of isometric tension and shortening velocity. We allowed all five steps in the cycle to be temperature-sensitive. Models with different starting combinations of enthalpy changes and activation enthalpies for the five steps were refined by downhill simplex runs and scored by their ability to fit experimental data on the temperature dependence of isometric tension and the relationship between force and shortening velocity in frog muscle. We conclude that the first tension-generating step may be weakly endothermic and that the rise of tension with temperature is largely driven by the preceding two strongly endothermic steps of ATP hydrolysis and attachment of M.ADP.Pi to actin. The refined model gave a reasonable fit to the available experimental data and after a temperature jump the overall rate of tension rise was much slower than after a length step as observed experimentally. The findings aid our understanding of the crossbridge cycle by showing that it may not be necessary to include an additional

  4. Orbital-scale nonlinear response of East Asian summer monsoon to its potential driving forces in the late Quaternary

    Science.gov (United States)

    Yi, Liang; Shi, Zhengguo; Tan, Liangcheng; Deng, Chenglong

    2017-06-01

    We conducted a statistical study to characterize the nonlinear response of the East Asian summer monsoon (EASM) to its potential forcing factors over the last 260 ka on orbital timescales. We find that both variation in solar insolation and global ice volume were responsible for the nonlinear forcing of orbital-scale monsoonal variations, accounting for 80% of the total variance. Specifically, EASM records with dominated precession variance exhibit a more sensitive response to changes in solar insolation during intervals of enhanced monsoon strength, but are less sensitive during intervals of reduced monsoon strength. In the case of global ice volume with 100-ka variance, this difference is not one of sensitivity but rather a difference in baseline conditions, such as the relative areas of land and sea which affected the land-sea thermal gradient. We therefore suggest that EASM records with dominated precession variance recorded the signal of a shift in the location of the Inter-tropical Convergence Zone, and the associated changes in the incidence of torrential rainfall; while for proxies with dominated 100-ka variance, it recorded changes in the land-sea thermal gradient via its effects on non-torrential precipitation.

  5. Dehydrogenation Kinetics and Modeling Studies of MgH2 Enhanced by Transition Metal Oxide Catalysts Using Constant Pressure Thermodynamic Driving Forces

    Directory of Open Access Journals (Sweden)

    Saidi Temitope Sabitu

    2012-06-01

    Full Text Available The influence of transition metal oxide catalysts (ZrO2, CeO2, Fe3O4 and Nb2O5 on the hydrogen desorption kinetics of MgH2 was investigated using constant pressure thermodynamic driving forces in which the ratio of the equilibrium plateau pressure (pm to the opposing plateau (pop was the same in all the reactions studied. The results showed Nb2O5 to be vastly superior to other catalysts for improving the thermodynamics and kinetics of MgH2. The modeling studies showed reaction at the phase boundary to be likely process controlling the reaction rates of all the systems studied.

  6. Linkage-Based Frameworks for Sustainability Assessment: Making a Case for Driving Force-Pressure-State-Exposure-Effect-Action (DPSEEA Frameworks

    Directory of Open Access Journals (Sweden)

    Brian Veitch

    2009-08-01

    Full Text Available The main objective of this paper is to discuss different approaches, identify challenges, and to select a framework for delivering effective sustainability assessments. Sustainable development is an idealistic concept and its assessment has always been a challenge. Several approaches, methodologies and conceptual frameworks have been developed in various disciplines, ranging from engineering to business and to policy making. The paper focuses mainly on various linkage-based frameworks and demonstrates that the driving force-state-exposure-effect-action (DPSEEA framework can be used to achieve sustained health benefits and environmental protection in accordance with the principles of sustainable development, especially because of its resemblance to the environmental risk assessment and management paradigms. The comparison of linkage-based frameworks is demonstrated through an example of sustainability in a higher educational institution.

  7. Driving Force to Explore the Urban Art and Design%城市艺术设计推动力探究

    Institute of Scientific and Technical Information of China (English)

    李焱

    2011-01-01

    个案例的列举与分析,探讨现有城市艺术设计的成就与问题。思考部分我国现状,为城市艺术设计发展进程总结出:政府支持,商业互利,公众参与,多方合作,国际交流,五点推动力以供参考。%Based on the percentage of bill in Philadelphia of United States,the European city of culture and artistic nature,Japan's international achievements and experience of three cases cited and analysis of existing urban art and design achievements and problems.Thinking part of our current situation,urban art and design development process for the sum of government support,business benefits,public participation,multilateral cooperation,international exchange,five driving force for reference.

  8. A Study on the Electromagnet Thrust force Characteristics of Newly Proposed Hybrid Bottom-mounted Control Rod Drive Mechanism for Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Hyung; Cho, Yeong Garp; Choi, Myoung Hwan; Yu, Je Yong; Kim, Ji Ho; Kim, Jong In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-05-15

    The control rod drive mechanism (CRDM) is the part of reactor regulating system (RRS), which is located in the reactor pool top (Top-mounted) or the room below the reactor pool (Bottom-mounted). The function of the CRDM is to insert, withdraw or maintain neutron absorbing material at any required position within the reactor core, in order to the reactivity control of the core. There are so many kinds of CRDM, such as magneticjack type, hydraulic type, rack and pinion type, chain type and linear or rotary step motor and so on. As a part of a new project, we have investigated the movable coil electromagnetic drive mechanism (MCEDM) which is new scheme for the reactor control rod adopted by China Advanced Research Reactor (CARR) as shown in Fig.1. To improve a better function of the electromagnetic and magnetic characteristics, new model CRDM, which is named a hybrid bottommounted CRDM (HBCRDM), is proposed. Especially in order to achieve improved thrust force, numerical magnetic field calculations between MCEDM and HBCRDM have been carried out and the HBCRDM FEM results have been compared with the MCEDM FEM results, and FEM results are summarized in the following sections

  9. Conformational gating of the electron transfer reaction QA−⋅QB → QAQB−⋅ in bacterial reaction centers of Rhodobacter sphaeroides determined by a driving force assay

    Science.gov (United States)

    Graige, M. S.; Feher, G.; Okamura, M. Y.

    1998-01-01

    The mechanism of the electron transfer reaction, QA−⋅QB → QAQB−⋅, was studied in isolated reaction centers from the photosynthetic bacterium Rhodobacter sphaeroides by replacing the native Q10 in the QA binding site with quinones having different redox potentials. These substitutions are expected to change the intrinsic electron transfer rate by changing the redox free energy (i.e., driving force) for electron transfer without affecting other events that may be associated with the electron transfer (e.g., protein dynamics or protonation). The electron transfer from QA−⋅ to QB was measured by three independent methods: a functional assay involving cytochrome c2 to measure the rate of QA−⋅ oxidation, optical kinetic spectroscopy to measure changes in semiquinone absorption, and kinetic near-IR spectroscopy to measure electrochromic shifts that occur in response to electron transfer. The results show that the rate of the observed electron transfer from QA−⋅ to QB does not change as the redox free energy for electron transfer is varied over a range of 150 meV. The strong temperature dependence of the observed rate rules out the possibility that the reaction is activationless. We conclude, therefore, that the independence of the observed rate on the driving force for electron transfer is due to conformational gating, that is, the rate limiting step is a conformational change required before electron transfer. This change is proposed to be the movement, controlled kinetically either by protein dynamics or intermolecular interactions, of QB by ≈5 Å as observed in the x-ray studies of Stowell et al. [Stowell, M. H. B., McPhillips, T. M., Rees, D. C., Soltis, S. M., Abresch, E. & Feher, G. (1997) Science 276, 812–816]. PMID:9751725

  10. ANALYSIS OF DRIVING FORCES ON THE CHANGE OF HISTORICAL FARMLAND USE IN SHANDONG PROVINCE DURING THE QING DYNASTY (1644-1911)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue-qin; GE Quan-sheng; ZHENG Jing-yun

    2003-01-01

    How land-cover has been changed by human use over the last 300 years is one of the five overarching questions guiding the Land-use/Cover Change (LUCC) Science/Research Plan. China has variety of historical docu-ments providing unique data superiority. So the characteristics of farmland area in Shandong Province during the Qing Dynasty (1644-1911) are summarized firstly: 1) the rising trend of farmland area was striking; 2) farmland area had re-markable fluctuation; 3) farmland area per capita decreased dramatically; 4) wasteland reclamation index increased rapidly. Then, the driving forces of farmland area change are analyzed. It is concluded that natural and human factors are jointly influential. Among the driving forces, human dimensions are the main factors of farn land area change,which direct the general tendency of the changes mentioned above. And the natural factors influence the stability of farmland area as well. Variation of the natural factors would act as the major contributory factor to farmland area change during years or periods of abrupt climatic changes, or during the intensive occurring periods of natural hazards.Besides, the passive aspects of human factors, such as war chaos also influenced the fluctuation of the farmland area.This research indicates that it is feasible to study the land-use/cover change by Chinese historical literatures, which has huge potential to provide a comprehensive picture of the growing dominance of human land-use and land-cover pat-terns that can be used in many global change research projects.

  11. European climate in the late twenty-first century: regional simulations with two driving global models and two forcing scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Raeisaenen, J. [Division of Atmospheric Sciences, Department of Physical Sciences, University of Helsinki, Gustaf Haellstroemin katu 2, PO Box 64, 00014, Helsinki (Finland); Rossby Centre, Swedish Meteorological and Hydrological Institute, 60176, Norrkoeping (Sweden); Hansson, U.; Ullerstig, A.; Doescher, R.; Graham, L.P.; Jones, C.; Meier, H.E.M.; Samuelsson, P.; Willen, U. [Rossby Centre, Swedish Meteorological and Hydrological Institute, 60176, Norrkoeping (Sweden)

    2004-01-01

    A basic analysis is presented for a series of regional climate change simulations that were conducted by the Swedish Rossby Centre and contribute to the PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects) project. For each of the two driving global models HadAM3H and ECHAM4/OPYC3, a 30-year control run and two 30-year scenario runs (based on the SRES A2 and B2 emission scenarios) were made with the regional model. In this way, four realizations of climate change from 1961-1990 to 2071-2100 were obtained. The simulated changes are larger for the A2 than the B2 scenario (although with few qualitative differences) and in most cases in the ECHAM4/OPYC3-driven (RE) than in the HadAM3H-driven (RH) regional simulations. In all the scenario runs, the warming in northern Europe is largest in winter or late autumn. In central and southern Europe, the warming peaks in summer when it locally reaches 10 C in the RE-A2 simulation and 6-7 C in the RH-A2 and RE-B2 simulations. The four simulations agree on a general increase in precipitation in northern Europe especially in winter and on a general decrease in precipitation in southern and central Europe in summer, but the magnitude and the geographical patterns of the change differ markedly between RH and RE. This reflects very different changes in the atmospheric circulation during the winter half-year, which also lead to quite different simulated changes in windiness. All four simulations show a large increase in the lowest minimum temperatures in northern, central and eastern Europe, most likely due to reduced snow cover. Extreme daily precipitation increases even in most of those areas where the mean annual precipitation decreases. (orig.)

  12. Polycation-π interactions are a driving force for molecular recognition by an intrinsically disordered oncoprotein family.

    Directory of Open Access Journals (Sweden)

    Jianhui Song

    Full Text Available Molecular recognition by intrinsically disordered proteins (IDPs commonly involves specific localized contacts and target-induced disorder to order transitions. However, some IDPs remain disordered in the bound state, a phenomenon coined "fuzziness", often characterized by IDP polyvalency, sequence-insensitivity and a dynamic ensemble of disordered bound-state conformations. Besides the above general features, specific biophysical models for fuzzy interactions are mostly lacking. The transcriptional activation domain of the Ewing's Sarcoma oncoprotein family (EAD is an IDP that exhibits many features of fuzziness, with multiple EAD aromatic side chains driving molecular recognition. Considering the prevalent role of cation-π interactions at various protein-protein interfaces, we hypothesized that EAD-target binding involves polycation- π contacts between a disordered EAD and basic residues on the target. Herein we evaluated the polycation-π hypothesis via functional and theoretical interrogation of EAD variants. The experimental effects of a range of EAD sequence variations, including aromatic number, aromatic density and charge perturbations, all support the cation-π model. Moreover, the activity trends observed are well captured by a coarse-grained EAD chain model and a corresponding analytical model based on interaction between EAD aromatics and surface cations of a generic globular target. EAD-target binding, in the context of pathological Ewing's Sarcoma oncoproteins, is thus seen to be driven by a balance between EAD conformational entropy and favorable EAD-target cation-π contacts. Such a highly versatile mode of molecular recognition offers a general conceptual framework for promiscuous target recognition by polyvalent IDPs.

  13. Polycation-π interactions are a driving force for molecular recognition by an intrinsically disordered oncoprotein family.

    Science.gov (United States)

    Song, Jianhui; Ng, Sheung Chun; Tompa, Peter; Lee, Kevin A W; Chan, Hue Sun

    2013-01-01

    Molecular recognition by intrinsically disordered proteins (IDPs) commonly involves specific localized contacts and target-induced disorder to order transitions. However, some IDPs remain disordered in the bound state, a phenomenon coined "fuzziness", often characterized by IDP polyvalency, sequence-insensitivity and a dynamic ensemble of disordered bound-state conformations. Besides the above general features, specific biophysical models for fuzzy interactions are mostly lacking. The transcriptional activation domain of the Ewing's Sarcoma oncoprotein family (EAD) is an IDP that exhibits many features of fuzziness, with multiple EAD aromatic side chains driving molecular recognition. Considering the prevalent role of cation-π interactions at various protein-protein interfaces, we hypothesized that EAD-target binding involves polycation- π contacts between a disordered EAD and basic residues on the target. Herein we evaluated the polycation-π hypothesis via functional and theoretical interrogation of EAD variants. The experimental effects of a range of EAD sequence variations, including aromatic number, aromatic density and charge perturbations, all support the cation-π model. Moreover, the activity trends observed are well captured by a coarse-grained EAD chain model and a corresponding analytical model based on interaction between EAD aromatics and surface cations of a generic globular target. EAD-target binding, in the context of pathological Ewing's Sarcoma oncoproteins, is thus seen to be driven by a balance between EAD conformational entropy and favorable EAD-target cation-π contacts. Such a highly versatile mode of molecular recognition offers a general conceptual framework for promiscuous target recognition by polyvalent IDPs.

  14. Driving force and development strategies of agro-tourism in China%驱动因素视角的我国农业旅游发展模式与策略研究

    Institute of Scientific and Technical Information of China (English)

    王灵恩; 何露; 成升魁; 闵庆文

    2012-01-01

    agro-tourism research and development in China for a more comprehensive knowledge about this sector. Foreign scholars have done so lot on the theory and empiricism of agro-tourism, community participation of women, diversification of operations, role of multi-functional agriculture and agro-heritage in tourism, impact of climate change on agro-tourism, sustainable development of agro-tourism, etc. Domestic scholars have focused mainly on empirical analysis of the concept of agro-tourism, state of development and countermeasures of agro-tourism, impacts of agro-tourism and festive tourism. This paper also analyzed the development of China's agro-tourism from the perspective of market demand, urbanization and rural economic restructuring. It discussed the driving forces of tourism demand, tourism development, accelerated urbanization, "re-turn-to-nature" drive, rural economic restructuring, agriculture, and tourism breakthrough achievement. Based on analysis of developments in China's agro-tourism, four driving forces were identified. The nation-wide tourism was driven by regional transportation, city development, scenic spot and resource monopoly. It was clear that the more driving factors there were, the more beneficial was the development of agro-tourism. The paper emphasized that under the concept of market economy, the development of agro-tourism always required a variety of external conditions for the jointly promotion of agro-tourism. Also with changing internal and external conditions, the driven factors for agro-tourism development changed. In conclusion therefore, development strategies were presented as the driving force of China's agro-tourism industry. Traffic-driven strategy and characteristics of product and urban development influenced strategic in-depth theme development of hot spot tourism sites. Link-driven development and unique-resource driven strategies were the brands of development for integrated mode of agro-tourism development. The development

  15. Intrinsic driving force of rural land integrated consolidation%农村土地综合整治的内在驱动力分析

    Institute of Scientific and Technical Information of China (English)

    邹伟; 胡莉; 林庶民; 胡锋

    2013-01-01

      为充分发挥农村土地综合整治的积极作用,从理论上探究其与城乡统筹发展的关系,从历史角度对其进行定位,并进行理论升华。在对农村土地整治内涵剖析的基础上,从经济、社会、政治3个方面分析农村土地综合整治的内在驱动力,揭示了农村土地综合整治对社会经济的积极影响,进而对农村土地综合整治进行了理性思考,最后从规划管理、决策机制、产权制度、收益分配、主导主体和配套制度等方面提出相关的对策建议,该文为进一步推进农村土地综合整治提供了较好的理论支撑和实践参考。%Urban-rural integrated development is one of the important topics of today's society and economic development in China. In recent years, being a crucial means of urban-rural integrated development, rural land integrated consolidation has received unprecedented advancement, which has also functioned positively in aspects such as alleviating the contradiction between supply and demand of land, changing farmers' production and lifestyle, and so on. However, issues such as farmers' being forced to go upstairs and poverty due to going upstairs which went against farmers' will and did harm to farmers' right appeared in some places, and those issues have a negative influence on propelling consolidation activity. Some researchers and management levels expressed doubts about it, and a land-management department was once forced to suspend the approval of relevant project. Now, it is very urgent to clarify the relationship between rural land integrated consolidation and the urban-rural integrated development theoretically, discuss the inner driving force, and to implement the theory. Firstly, from the perspective of concept refreshment, this paper makes fundamental analysis of the connotation, nature, function, and significance of rural land integrated consolidation under urban-rural integrated development, proposes

  16. 基于创业网络的科技企业孵化器外部创新驱动机制%The external innovation drive mechanism of technology enterprises incubator on the perspective of entrepreneurial network

    Institute of Scientific and Technical Information of China (English)

    阎明宇

    2014-01-01

    Technology business incubators mainly utilizes the network to provide support for the incu-bated enterprises . T herefore ,the research of technology business incubators entrepreneurial net-work’s main function and external innovation driving mechanism have been emphasized in recent years .Based on the incubation function of technology business incubators ,technology enterprises can easily build its entrepreneurial network .The subjects of this entrepreneurial network include the gov-ernment ,affiliates ,financial institutions ,agencies ,universities and research institutions .T he entrepre-neurial network which make up of these subjects can synergy ,form a drive mechanism which consist of technical supportive drive mechanism ,find supportive drive mechanism and opportunity supportive drive mechanism .It can drive the external technological innovation of new ventures and finally com-bine with the internal technological innovation drive mechanism cultivating competitive strategic re-sources ,w hich is essential to the survival and development of new ventures .%由于科技企业孵化器主要是通过组织网络来为在孵企业提供支持的,因此,基于组织网络角度对科技企业孵化器创业网络主体功能、外部创新驱动机制等的研究,近年来备受重视。认为依托科技企业孵化器的孵化功能,初创的科技企业能够更加容易地构建创业网络,其主体主要包括政府部门、相关企业、金融机构、大学、科研机构以及中介机构。基于这些网络主体构成的创业网络则可以发挥协同作用,形成一个从技术支持、资金支持到机会支持的三大机制相互协调、相互促进的科技企业外部创新驱动机制,从新创科技企业外部寻求驱动其创新的因素。并最终结合企业自身的内部创新驱动机制进行技术创新,培养出具有竞争优势的战略资源,使其具备必要的生存和发展能力。

  17. 基于EKF的Duffing振子正弦策动力判别算法%Identification of Sine Driving Force of Duffing Oscillator Based on Extended Kalman Filter

    Institute of Scientific and Technical Information of China (English)

    芮国胜; 张洋; 张嵩; 苗俊

    2012-01-01

    以Duffing振子系统为研究对象,分析了以正弦函数为周期策动力的Duffing方程基本形式及相应的振子运动,并用扩展卡尔曼滤波(extended Kalnan filter,EKF)对Duffing振子系统进行递推滤波,实现了对Duffing振子系统的稳定估计.根据滤波过程中周期策动力随卡尔曼增益的变化,提出了一种基于卡尔曼增益判别Duffing振子系统周期策动力的方法,可以作为运用Duffing振子进行弱信号检测的依据.仿真结果表明,与经典Lyapunov指数判别法相比,该算法具有更好的判别性能.%In studying Duffing oscillator systems, a basic model using sine function as a periodic driving force and the system oscillator's movement are analyzed. Extended Kalman filter is used to process and estimate the Duffing oscillator system according to the change of the Kalman gain in the filtering process. A method using the Kalman gain to identify the periodic force is proposed, which can be used for weak signal detection with a Duffing oscillator. Simulations show performance improvement as compared with the Lypunov exponent method.

  18. Crystal structure of a trapped catalytic intermediate suggests that forced atomic proximity drives the catalysis of mIPS.

    Science.gov (United States)

    Neelon, Kelly; Roberts, Mary F; Stec, Boguslaw

    2011-12-07

    1-L-myo-inositol-phosphate synthase (mIPS) catalyzes the first step of the unique, de novo pathway of inositol biosynthesis. However, details about the complex mIPS catalytic mechanism, which requires oxidation, enolization, intramolecular aldol cyclization, and reduction, are not fully known. To gain further insight into this mechanism, we determined the crystal structure of the wild-type mIPS from Archaeoglobus fulgidus at 1.7 Å, as well as the crystal structures of three active-site mutants. Additionally, we obtained the structure of mIPS with a trapped 5-keto-glucose-6-phosphate intermediate at 2 Å resolution by a novel (to our knowledge) process of activating the crystal at high temperature. A comparison of all of the crystal structures of mIPS described in this work suggests a novel type of catalytic mechanism that relies on the forced atomic proximity of functional groups. The lysine cluster is contained in a small volume in the active site, where random motions of these side chains are responsible for the progress of the complex multistep reaction as well as for the low rate of catalysis. The mechanism requires that functional groups of Lys-274, Lys-278, Lys-306, and Lys-367 assume differential roles in the protonation/deprotonation steps that must occur during the mIPS reaction. This mechanism is supported by the complete loss of activity of the enzyme caused by the Leu-257 mutation to Ala that releases the lysine containment.

  19. Mediterranean coastal dune vegetation: Are disturbance and stress the key selective forces that drive the psammophilous succession?

    Science.gov (United States)

    Ciccarelli, Daniela

    2015-11-01

    Plant communities of coastal dunes are distributed along a characteristic sea-inland gradient. Generally, there is a shift from annual and short height species with small leaves in the initial successional stages to perennial tall shrubs with tough leaves in later phases. Assessing the community-weighted mean (CWM) trait values is used in plant ecology to describe ecosystem properties especially during succession. In particular, CSR (Competitive, Stress-tolerant, and Ruderal strategy) classification allows us to explore community functional shifts in terms of disturbance, stress and competition selective forces. The functional basis of the psammophilous succession was studied based on the following questions: (1) Can we circumscribe different functional types among plant species of Mediterranean coastal dunes? (2) How do CWM trait values vary along the environmental sea-inland gradient? (3) What is the relative importance of competition, stress and disturbance in the processes of plant community assembling? (4) Can we postulate that along primary successions there is generally a shift from ruderality to stress-tolerance? An explorative analysis of functional groups was performed by Non-Metric Multidimensional Scaling (NMDS) analysing nine morpho-functional traits measured for 45 taxa from 880 dune plots localised in Tuscany (central Italy, Europe). NMDS ordination showed a scattered distribution of psammophytes that could not be delimited in precise plant functional types. The first NMDS axis has been interpreted as a leaf economics axis because it was correlated to leaf area (LA) and leaf dry matter content (LDMC), while the second one was a plant size axis because of its correlation with canopy height. Along the sea-inland gradient, pioneer plant communities of upper beach were dominated by ruderals (with the lowest values of LDMC and specific leaf area - SLA), well-adapted to the harsh environmental conditions of coastal dunes. More distant from the sea, where

  20. New-type driving forces of urban agglomerations development in China%中国城市群发育的新型驱动力研究

    Institute of Scientific and Technical Information of China (English)

    王婧; 方创琳

    2011-01-01

    Urban agglomeration (UA) is a new terrain unit involved in international competition and international division of labor. With the development of economic globalization and the boot of information and technology, UAs in China have developed gradually. In this process, five new-type driving forces (DF) have appeared, which are economic globalization, new-type industrialization, informatization, rapid transportation and government dominant, and studies on the five ones have important value. Based on analysis of mechanism of five new-type DF for UA and comparative analysis of some relative indexes, it is found out as follows: economic globalization drives UAs enter the international system and the higher level of UAs opening and the more industrial and technology transfers, the better UAs develop under the background of economic globalization; new-type industrialization drives UAs become manufacturing bases which injects new energies for development,and the higher level of industrialization and the better high-tech industry develops, the better UAs develop; informatization integrates all information and drives them flow at a high speed, and the higher level of informatization, the better UAs develop under the background of informatization age; transportation is the channel for materials and information exchange, and rapid transportation impels UAs to be connected closely and builds up the foundation of UAs development; new correlative policy is like a roll booster for impelling UAs development, in a correct way. Based on the above analysis, the paper suggests that further studies towards UAs development in China should focus on spatial and temporal differences of DFs and braking forces.%城市群是国家参与全球竞争和国际分工的全新地域单元,城市群发育对于推进城市化进程、增强综合国力具有显著作用,研究城市群发育驱动力具有重要价值.伴随着不断加强的全球化、信息化进程,中国城市群逐渐发育

  1. Differential thermodynamic driving force of first- and second-generation antihistamines to determine their binding affinity for human H1 receptors.

    Science.gov (United States)

    Hishinuma, Shigeru; Sugawara, Kenta; Uesawa, Yoshihiro; Fukui, Hiroyuki; Shoji, Masaru

    2014-09-15

    Differential binding sites for first- and second-generation antihistamines were indicated on the basis of the crystal structure of human histamine H1 receptors. In this study, we evaluated differences between the thermodynamic driving forces of first- and second-generation antihistamines for human H1 receptors and their structural determinants. The binding enthalpy and entropy of 20 antihistamines were estimated with the van't Hoff equation using their dissociation constants obtained from their displacement curves against the binding of [(3)H]mepyramine to membrane preparations of Chinese hamster ovary cells expressing human H1 receptors at various temperatures from 4°C to 37°C. Structural determinants of antihistamines for their thermodynamic binding properties were assessed by quantitative structure-activity relationship (QSAR) analyses. We found that entropy-dependent binding was more evident in second- than first-generation antihistamines, resulting in enthalpy-entropy compensation between the binding forces of first- and second-generation antihistamines. QSAR analyses indicated that enthalpy-entropy compensation was determined by the sum of degrees, maximal electrostatic potentials, water-accessible surface area and hydrogen binding acceptor count of antihistamines to regulate their affinity for receptors. In conclusion, it was revealed that entropy-dependent hydrophobic interaction was more important in the binding of second-generation antihistamines, even though the hydrophilicity of second-generation antihistamines is generally increased. Furthermore, their structural determinants responsible for enthalpy-entropy compensation were explored by QSAR analyses. These findings may contribute to understanding the fundamental mechanisms of how the affinity of ligands for their receptors is regulated.

  2. Daylighting as the Driving Force of the Design Process: from the Results of a Survey to the Implementation into an Advanced Daylighting Project

    Directory of Open Access Journals (Sweden)

    Valerio R.M. Lo Verso

    2014-12-01

    Full Text Available This paper presents a study for the transformation of an industrial area in Turin, Italy. The area hosts two buildings (one of which appointed as listed to be transformed into dwellings. A synergic approach was adopted which combined expertise from architecture, social-economics, psychology and building physics sciences. Building physics sciences lead the research team. A user-centered design was pursued, using a bottom-up approach. A specifically developed questionnaire was submitted on-line to potential users. The survey showed that ‘amount of daylight’, ‘size of rooms’, ‘tranquility of the area’ and ‘presence of a private garden’ were perceived by users to be the most positive aspects of both their present and future, ideal home. These results were then implemented into the project. The exploitation of daylight became the driving force of the transformation project. Especially for the listed building, skylights and light wells were designed to bring daylight into the cores of the buildings, which host common spaces such as libraries or study rooms. The amount of daylight was assessed through the legislative index of the average daylight factor and through a climate-based modeling approach, calculating dynamic metrics such as the spatial daylight autonomy and the Useful Daylight Illuminance. The paper critically compares and discusses these two approaches. Finally, the energy demand for lighting was also calculated to analyze how the increased exploitation of daylight may imply a reduced need for electricity for lighting.

  3. Background, driving force and constraints to build smart grids%智能电网的背景、推动力和制约

    Institute of Scientific and Technical Information of China (English)

    穆钢; 肖白

    2012-01-01

    The scope of smart grids was discussed in this paper. The background, the driving forces and the constraints of smart grids were investigated. And some emerging frontier technologies of smart grids were summarized. For the new challenges of large scale renewable generation incorporating to grid, the comprehensive strategies should be adopted to multi-aspects (power generation side, grid side and load side) to overcome the side effects of grid renewable generation. Many countermeasures can be taken to achieve the well power generation at power generation side, unhindered power transmission at grid side and proper utilization at load side.%讨论智能电网的范畴,分析智能电网发展的背景、推动力和制约,概述智能电网的几个前沿领域.针对智能电网面临的“大规模可再生能源接入”新挑战,指出克服其影响应多管齐下、综合施策.分别讨论在电源侧、电网侧和负荷侧可以采取的对策,以实现电源侧发得好、电网侧送得出、负荷侧用得巧.

  4. A thermo-mechanical correlation with driving forces for hcp martensite and twin formations in the Fe–Mn–C system exhibiting multicomposition sets

    Directory of Open Access Journals (Sweden)

    Jinichiro Nakano

    2013-01-01

    Full Text Available The thermodynamic properties of the Fe–Mn–C system were investigated by using an analytical model constructed by a CALPHAD approach. The stacking fault energy (SFE of the fcc structure with respect to the hcp phase was always constant at T0, independent of the composition and temperature when other related parameters were assumed to be constant. Experimental limits for the thermal hcp formation and the mechanical (deformation-induced hcp formation were separated by the SFE at T0. The driving force for the fcc to hcp transition, defined as a dimensionless value –dGm/(RT, was determined in the presence of Fe-rich and Mn-rich composition sets in each phase. Carbon tended to partition to the Mn-rich phase rather than to the Fe-rich phase for the compositions studied. The results obtained revealed a thermo-mechanical correlation with empirical yield strength, maximum true stress and maximum true strain. The proportionality between thermodynamics and mechanical properties is discussed.

  5. Long-term Dynamics of Cultivated Land Resources and Their Driving Forces of Guyuan City in Upper Reaches of Jinghe River

    Institute of Scientific and Technical Information of China (English)

    CHEN Caocao; XIE Gaodi; ZHEN Lin; LENG Yunfa

    2008-01-01

    The land use patterns in Guyuan City, Ningxia Hui Autonomous Region of China, have changed greatlyover the years, due to population growth and farming and stock raising development. This study, using 50-year statis-tical data of cultivated land and 14-year spatial data of land use pattern, analyzed the developmental stages, the char-acter, and the spatial variance of farmland in the city, and discussed the driving forces of cultivated land changes basedon empirical and conceptual statistical models. First, the change of cultivated land area went through different stages ofrapid increase, fluctuating change, decrease and rapid decrease from 1949 to 2004, additionally, social and economicpolicies in different stages had an important impact on farmland variance. Second, from 1986 to 2000, the quantity ofcultivated land increased, but its quality decreased. Third, social and economic factors are determinant factors in culti-vated land transition. Five constructed paths explain cultivated land transition. Factors that have direct or indirect ef-fects on farmland include the economy (Xeco), the population (Xpop), agricultural output (Xagr), and scientific input (Xsci).The sequence of impact was Xeco>Xpop>Xsci>Xagr. Among all these impacts, Xeco was the major positive one, and Xpopwas the major negative one. It is urgent to take measures or adopt a policy to stop the vicious cycle in coo-environmentand agriculture production. Otherwise, negative patterns of farmland use will increase, and high-quality cultivated landwill continue to decline.

  6. A thermo-mechanical correlation with driving forces for hcp martensite and twin formations in the Fe-Mn-C system exhibiting multicomposition sets.

    Science.gov (United States)

    Nakano, Jinichiro

    2013-02-01

    The thermodynamic properties of the Fe-Mn-C system were investigated by using an analytical model constructed by a CALPHAD approach. The stacking fault energy (SFE) of the fcc structure with respect to the hcp phase was always constant at T0, independent of the composition and temperature when other related parameters were assumed to be constant. Experimental limits for the thermal hcp formation and the mechanical (deformation-induced) hcp formation were separated by the SFE at T0. The driving force for the fcc to hcp transition, defined as a dimensionless value -dGm/(RT), was determined in the presence of Fe-rich and Mn-rich composition sets in each phase. Carbon tended to partition to the Mn-rich phase rather than to the Fe-rich phase for the compositions studied. The results obtained revealed a thermo-mechanical correlation with empirical yield strength, maximum true stress and maximum true strain. The proportionality between thermodynamics and mechanical properties is discussed.

  7. Driving forces in researchers mobility

    CERN Document Server

    Gargiulo, Floriana

    2013-01-01

    Starting from the dataset of the publication corpus of the APS during the period 1955-2009, we reconstruct the individual researchers trajectories, namely the list of the consecutive affiliations for each scholar. Crossing this information with different geographic datasets we embed these trajectories in a spatial framework. Using methods from network theory and complex systems analysis we characterise these patterns in terms of topological network properties and we analyse the dependence of an academic path across different dimensions: the distance between two subsequent positions, the relative importance of the institutions (in terms of number of publications) and some socio-cultural traits. We show that distance is not always a good predictor for the next affiliation while other factors like "the previous steps" of the career of the researchers (in particular the first position) or the linguistic and historical similarity between two countries can have an important impact. Finally we show that the dataset ...

  8. Effect of External Forced Flow and Boiling Film on Heat Transfer of AISI 4140 Steel Horizontal Rod During Direct Quenching%Effect of External Forced Flow and Boiling Film on Heat Transfer of AISI 4140 Steel Horizontal Rod During Direct Quenching

    Institute of Scientific and Technical Information of China (English)

    A H Meysami; R Ghasemzadeh; S H Seyedein; M R Aboutalebi

    2011-01-01

    The effects of rod falling and moving, external flow field, boiling film and radiation were investigated on fluid flow and heat transfer of AISI 4140 steel horizontal rod during direct quenching by mathematical modeling. The flow field and heat transfer in quenching tank were simulated by computational fluid dynamics (CFD) method considering falling and moving of rods during process. Therefore, modeling of flow field was done by a fixed-mesh method for general moving objects equations, and then, energy equation was solved with a numerical approach so that effeet of boiling film heat flux was considered as a source term in energy equation for solid-liquid boundary. Simulated results were verified by comparing with published and experimental data and there was a good agreement between them. Also, the effects of external forced flow and film boiling were investigated on heat flux output, temperature distribution and heat transfer coefficient of rod. Also simulated results determined optimum quenching time for this process.

  9. Seasonal and Interannual Fast-Ice Variability from MODIS Surface-Temperature Anomalies, and its Link to External Forcings in Atka Bay, Antarctica

    Science.gov (United States)

    Paul, S.; Hoppmann, M.; Willmes, S.; Heinemann, G.

    2016-12-01

    Around Antarctica, sea ice is regularly attached to coastal features. These regions of mostly seasonal fast ice interact with the atmosphere, ocean and coastal ecosystem in a variety of ways. The growth and breakup cycles may depend on different factors, such as water- and air temperatures, wind conditions, tides, ocean swell, the passage of icebergs and the presence of nearby polynyas. However, a detailed understanding about the interaction between these factors and the fast-ice cycle is missing. In order to better understand the linkages between general fast-ice evolution and external forcing factors, we present results from an observational case study performed on the seasonal fast-ice cover of Atka Bay, eastern Weddell Sea. The ice conditions in this region are critical for the supply of the German wintering station Neumayer III. Moreover, the fast ice at Atka Bay hosts a unique ecosystem based on the presence of a sub-ice platelet layer and a large emperor penguin colony. While some qualitative characterizations on the seasonal fast-ice cycle in this region exist, no proper quantification was carried out to date. The backbone of this work is a new algorithm, which yields the first continuous time series of open-water fractions from Moderate-Resolution Imaging Spectroradiometer (MODIS) surface temperatures. The open-water fractions are derived from a range of running multi-day median temperature composites, utilizing the thermal footprint of warm open water and thin ice in contrast to cold pack-ice/ice-shelf areas. This unique, and manually validated dataset allows us to monitor changes in fast-ice extent on a near daily basis, for a period of 14 years (2002-2015). In a second step, we combine these results with iceberg observations, data from the meteorological observatory, and auxiliary satellite data in order to identify the main factors governing fast-ice formation and break-up.

  10. Analysis on Farmland Changes and the Driving Forces in Shijiazhuang%石家庄市耕地变化及其驱动力分析

    Institute of Scientific and Technical Information of China (English)

    刘巧芹; 连季婷; 宁玉萍; 郭爱请; 秦岭; 齐志国

    2012-01-01

    In order to draw up viable farmland protection measures and intensive land use standards of urban and rural settlements, farmland changes and the driving forces were analyzed by comparative analysis and principal component analysis. The results showed that: total arable land and per capita farmland showed a decreasing trend; the reducing rate of cultivated land in fast economic development year was bigger than that of in slow development time, and the counties with high levels of economic development had higher reducing rate than the counties with low levels of economic development; among the factors of farmland reduction, economic development was the fundamental driving factor, population growth was an important one, technological progress and ascension of multiple cropping index compensate for the loss of production capacity of arable land, and the national policy had an important impact on the reduction rate of farmland; protection of farmland should be enhanced from population controlled, the construction land planned scientifically and controlled strictly, and the protection of basic farmland strengthened, etc so that the relationship between human and land coordinates develop in Shijiazhuang.%为了制定切实可行的耕地保护措施和城乡居民点集约用地标准,应用对比分析和主成分分析法,分析了石家庄市耕地变化特征及其驱动力.结果表明,石家庄市耕地总面积和人均耕地面积呈现减少趋势,减少速率时间和区域差异明显,经济发展速度快的年份和经济发展水平高的县市减少速率大;经济发展是耕地减少的根本动力,人口增长是耕地减少的重要因素,科技进步和复种指数提高补偿了耕地减少的产能损失,国家政策松紧对耕地减少速率具有重要影响;应从控制人口数量、科学规划并严格控制建设用地、加强基本农田保护等方面加强耕地保护,以促进区域人地关系协调发展.

  11. 多倍化是杂草起源与演化的驱动力%Polyploidization, one of the driving forces for weed origin and evolution

    Institute of Scientific and Technical Information of China (English)

    李君; 强胜

    2012-01-01

    杂草及外来植物入侵给全球经济发展及生态环境都带来了严重危害,研究其起源与演化将有助于它们的管理与控制.多倍化是植物进化的主要驱动力量,然而多倍化在杂草起源与演化中的作用还停留在种类统计以及零碎的研究案例证据上.本文综述了植物多倍体基因组结构及基因表达的研究进展以及染色体加倍后的生态学效应.多倍化促进了基因组水平与表型水平的进化,影响物种或群体生存竞争能力和繁殖扩展能力,提高物种或群体生态适应性.这一遗传过程可能促使外来种在新的生境中的成功入侵进而转变为杂草,并提出重视开展对杂草及外来入侵植物的多倍化研究的设想.%Weeds and alien invasive plants have caused tremendously ecological and socio-economic damages and loses worldwide, therefore,it is important to study origin and evolution of weeds for their effective management. Polyploidy is believed to be the main driving force of plant evolution, however, its playing the role in weeds origin and evolution is poorly understood. In this paper we review the progresses on the polyploid genome structure and gene expression and the ecological consequences of chromosome doubling. The polyploidy promotes the evolution of genomic and phenotype, affects the species survival competition, reproduction and expansion capability, and improves the ecological adaptability. Polyploidization can drive the successful invasion of invasive alien species and consequently evolution into a weed in new habitats. In addition, it is proposed that the research works on invasive alien plants may focus on polyploidization function in weed evolution and alien plant invasion.

  12. Assessing driving forces of land use and land cover change by a mixed-method approach in north-eastern Ghana, West Africa.

    Science.gov (United States)

    Kleemann, Janina; Baysal, Gülendam; Bulley, Henry N N; Fürst, Christine

    2017-03-20

    Land use and land cover change (LULCC) is the result of complex human-environmental interactions. The high interdependencies in social-ecological systems make it difficult to identify the main drivers. However, knowledge of key drivers of LULCC, including indirect (underlying) drivers which cannot be easily determined by spatial or economic analyses, is essential for land use planning and especially important in developing countries. We used a mixed-method approach in order to detect drivers of LULCC in the Upper East Region of northern Ghana by different qualitative and quantitative methods which were compared in a confidence level analysis. Viewpoints from experts help to answer why the land use is changing, since many triggering effects, especially non-spatial and indirect drivers of LULCC, are not measurable by other methodological approaches. Geo-statistical or economic analyses add to validate the relevance of the expert-based results. First, we conducted in-depth interviews and developed a list of 34 direct and indirect drivers of LULCC. Subsequently, a group of experts was asked in a questionnaire to select the most important drivers by using a Likert scale. This information was complemented by remote sensing analysis. Finally, the driver analysis was compared to information from literature. Based on these analyses there is a very high confidence that population growth, especially in rural areas, is a major driver of LULCC. Further, current farming practice, bush fires, livestock, the road network and climate variability were the main direct drivers while the financial capital of farmers and customary norms regarding land tenure were listed as important indirect drivers with high confidence. Many of these driving forces, such as labour shortage and migration, are furthermore interdependent. Governmental laws, credits, the service by extension officers, conservational agriculture and foreign agricultural medium-scale investments are currently not driving

  13. H2O-rich melt inclusions in fayalitic olivine from Hekla volcano: Implications for phase relationships in silicic systems and driving forces of explosive volcanism on Iceland

    Science.gov (United States)

    Portnyagin, Maxim; Hoernle, Kaj; Storm, Sonja; Mironov, Nikita; van den Bogaard, Christel; Botcharnikov, Roman

    2012-12-01

    Silicic Icelandic magmas are widely believed to contain low to moderate H2O content prior to degassing, and that their high explosivity mostly results from the interaction of the magmas with ice or meteoric water. Here we report the compositions of glass inclusions (SiO2=57-72 wt%, K2O=1.3-2.6 wt%) in Fe-rich olivines (Fo2-42) from the largest Holocene eruptions of Hekla volcano (H3 and H4) on Iceland, which preserved quenched melts with very high primary H2O contents (3.3-6.2 wt%). The silicic Hekla melts originate primarily by extensive (˜90%) crystal fractionation of H2O-poor (˜0.6 wt%) basalts and represent an end member in the systematics of terrestrial magmas because they originate at low fO2 (ΔQFM ˜-0.1 to -0.4) and have as high H2O contents as significantly more oxidized island-arc magmas (ΔQFM≥1). This demonstrates that H2O and ΔQFM do not correlate in silicic magmas from different tectonic settings, and that fO2, not H2O content, shows a major difference between silicic ocean-island (e.g., Icelandic) and island-arc magmas. Analysis of available experimental data suggests that high H2O activity and low fO2 expand the field of olivine stability in silicic melts. Low fO2 and low MgO content could also suppress crystallization of amphibole. On the basis of these results we propose that an anhydrous mineral assemblage bearing Fe-rich olivine in evolved volcanic and Skaergaard-type intrusive rocks does not imply low H2O in magmas prior to degassing but, in contrast to the commonly held view, is an indicator of H2O-rich silicic parental magmas crystallized at low fO2. Finally, the high H2O content in magma was a major driving force of the largest explosive eruptions of Hekla volcano and must be at least as important for driving silicic explosive volcanism on Iceland as magma-ice interaction.

  14. Drive Stands

    Data.gov (United States)

    Federal Laboratory Consortium — The Electrical Systems Laboratory (ESL)houses numerous electrically driven drive stands. A drive stand consists of an electric motor driving a gearbox and a mounting...

  15. Loss of TAK1 increases cell traction force in a ROS-dependent manner to drive epithelial–mesenchymal transition of cancer cells

    Science.gov (United States)

    Lam, C R I; Tan, C; Teo, Z; Tay, C Y; Phua, T; Wu, Y L; Cai, P Q; Tan, L P; Chen, X; Zhu, P; Tan, N S

    2013-01-01

    Epithelial–mesenchymal transition (EMT) is a crucial step in tumor progression, and the TGFβ–SMAD signaling pathway as an inductor of EMT in many tumor types is well recognized. However, the role of non-canonical TGFβ–TAK1 signaling in EMT remains unclear. Herein, we show that TAK1 deficiency drives metastatic skin squamous cell carcinoma earlier into EMT that is conditional on the elevated cellular ROS level. The expression of TAK1 is consistently reduced in invasive squamous cell carcinoma biopsies. Tumors derived from TAK1-deficient cells also exhibited pronounced invasive morphology. TAK1-deficient cancer cells adopt a more mesenchymal morphology characterized by higher number of focal adhesions, increase surface expression of integrin α5β1 and active Rac1. Notably, these mutant cells exert an increased cell traction force, an early cellular response during TGFβ1-induced EMT. The mRNA level of ZEB1 and SNAIL, transcription factors associated with mesenchymal phenotype is also upregulated in TAK1-deficient cancer cells compared with control cancer cells. We further show that TAK1 modulates Rac1 and RhoA GTPases activities via a redox-dependent downregulation of RhoA by Rac1, which involves the oxidative modification of low-molecular weight protein tyrosine phosphatase. Importantly, the treatment of TAK1-deficient cancer cells with Y27632, a selective inhibitor of Rho-associated protein kinase and antioxidant N-acetylcysteine augment and hinders EMT, respectively. Our findings suggest that a dysregulated balance in the activation of TGFβ–TAK1 and TGFβ–SMAD pathways is pivotal for TGFβ1-induced EMT. Thus, TAK1 deficiency in metastatic cancer cells increases integrin:Rac-induced ROS, which negatively regulated Rho by LMW-PTP to accelerate EMT. PMID:24113182

  16. Interactions between seasonality and oceanic forcing drive the phytoplankton variability in the tropical-temperate transition zone (~ 30°S) of Eastern Australia

    Science.gov (United States)

    Armbrecht, Linda H.; Schaeffer, Amandine; Roughan, Moninya; Armand, Leanne K.

    2015-04-01

    The East Australian Current (EAC) has been shown to be warming rapidly, which is expected to cause latitudinal shifts in phytoplankton abundance, distribution and composition along the east Australian coast. Yet a lack of phytoplankton information exists northward of 34°S. Here, we provide the first detailed taxonomic time-series survey (monthly sampling for about one annual cycle, 2011-2012) in the east Australian tropical-temperate transition zone (~ 30°S, upstream of the EAC separation point at ~ 31-32°S). All phytoplankton (categorised depending on their association with specific water-types) show a seasonal signal with abundance maxima (minima) during summer (winter). This seasonal signal is most pronounced in the seasonal/bloom category and least expressed by deep-water taxa, which prefer cold, saline and dense bottom water independent of the season. Different extents of EAC encroachment onto the continental shelf drive the cross-shelf phytoplankton composition and distribution, such that a weak EAC is associated with phytoplankton community being organised along 'depth' and 'distance from the coast' gradients with high phytoplankton abundances inshore. A strong EAC favours the occurrence of warm-water taxa offshore and an increase in diatom abundance on the mid-shelf (53% shelf width). We conclude that the phytoplankton community in the tropical-temperate transition zone of Eastern Australia is driven by an interaction of intrinsic seasonal cycles and primarily EAC-driven oceanic forcing. Our findings benefit studies located in Western Boundary Current systems worldwide, in which warming and strengthening of these currents are predicted to severely impact phytoplankton dynamics.

  17. Loss of TAK1 increases cell traction force in a ROS-dependent manner to drive epithelial-mesenchymal transition of cancer cells.

    Science.gov (United States)

    Lam, C R I; Tan, C; Teo, Z; Tay, C Y; Phua, T; Wu, Y L; Cai, P Q; Tan, L P; Chen, X; Zhu, P; Tan, N S

    2013-10-10

    Epithelial-mesenchymal transition (EMT) is a crucial step in tumor progression, and the TGFβ-SMAD signaling pathway as an inductor of EMT in many tumor types is well recognized. However, the role of non-canonical TGFβ-TAK1 signaling in EMT remains unclear. Herein, we show that TAK1 deficiency drives metastatic skin squamous cell carcinoma earlier into EMT that is conditional on the elevated cellular ROS level. The expression of TAK1 is consistently reduced in invasive squamous cell carcinoma biopsies. Tumors derived from TAK1-deficient cells also exhibited pronounced invasive morphology. TAK1-deficient cancer cells adopt a more mesenchymal morphology characterized by higher number of focal adhesions, increase surface expression of integrin α5β1 and active Rac1. Notably, these mutant cells exert an increased cell traction force, an early cellular response during TGFβ1-induced EMT. The mRNA level of ZEB1 and SNAIL, transcription factors associated with mesenchymal phenotype is also upregulated in TAK1-deficient cancer cells compared with control cancer cells. We further show that TAK1 modulates Rac1 and RhoA GTPases activities via a redox-dependent downregulation of RhoA by Rac1, which involves the oxidative modification of low-molecular weight protein tyrosine phosphatase. Importantly, the treatment of TAK1-deficient cancer cells with Y27632, a selective inhibitor of Rho-associated protein kinase and antioxidant N-acetylcysteine augment and hinders EMT, respectively. Our findings suggest that a dysregulated balance in the activation of TGFβ-TAK1 and TGFβ-SMAD pathways is pivotal for TGFβ1-induced EMT. Thus, TAK1 deficiency in metastatic cancer cells increases integrin:Rac-induced ROS, which negatively regulated Rho by LMW-PTP to accelerate EMT.

  18. On Driving Force and Strategy of Brand Management Strategy in Universities%大学品牌经营战略源动力与策略研究

    Institute of Scientific and Technical Information of China (English)

    郑哲文; 周铁军

    2012-01-01

    China’s higher education benefits much from the enhancement of economic strength and the vast demand for talent in its scale and educational strength development,which is bound to be faced with new challenges.The implementation of the university brand strategy,strengthening the brand management strategy and enhancing the strength of universities is both an imperative that work and a long-term strategy of China’s education departments and the government.The survey data analysis for the driving force for brand management building shows that it is necessary to integrate the will of all the staff and students,assess the situation and establish brand awareness,and form the brand management strategy in line with the times.The paper proposes that the university should focus on brand management strategy and issues to emphasize.%我国的高等教育规模与教育实力发展得益于我国经济实力的增强和社会对人才的大量需求,也必然面临新的挑战;实施高校品牌战略,强化品牌经营战略,提升高校实力,是一件刻不容缓的工作,是我国教育部门和政府一项长远战略;对品牌经营建设源动力调查数据分析表明汇聚全体师生员工意愿、审时度势、树立品牌意识一、制定品牌经营战略是十分必要的和符合时势的,并提出了对大学品牌经营策略和应注重的问题。

  19. 西安市户外运动市场驱动力分析%Analysis of the driving forces of Xi'an city outdoor sports market

    Institute of Scientific and Technical Information of China (English)

    刘格平; 路锋辉

    2013-01-01

    In order to promote the development of Xi'an city outdoor sports market,driving force of Xi'an city outdoor sports market development is analyzed through literature review and interview method.Results show that the development of natural resources,human resources,tourism resources play the important role in the outdoor sports market development,but the outdoor sports investment is another important part;perfect the laws and policies to help the market,but should cultivate the participants of outdoor sprots; developing market organization helps the development of marketization.To cultivate compound talents,focusing on sports,is essential to promote the development of outdoor sports market.%针对西安市户外运动发展中存在的问题,分析西安市户外运动市场驱动力.研究表明,开发自然资源、人文资源、旅游资源对户外运动市场化发展具有重要作用,但是应注重户外运动本身的投入;完善法规制度,出台政策有助于市场培育,但应把握好户外运动发展参与者的培育;发展市场组织机构,有利于户外运动企业化、俱乐部模式运作,对于促进市场化发展具有重要的意义,但应把握好行业发展的关键,而不是过分追求经济效益.培育复合型人才,侧重体育,是推进户外运动市场发展的重要内容.

  20. Influence of external disturbances to dynamic balance of the semi-anthropomimetic robot

    Directory of Open Access Journals (Sweden)

    Petrović Vladimir M.

    2014-01-01

    Full Text Available The idea of building an artificial man extends through the entire history of mankind. In this paper we present a semi-anthropomimetic robot, as a structure that consists of an upper human-like body mounted on a cart (mobile platform. Semi-anthropomimetic robot uses the three-wheeled mobile platform (two driving wheels and one passive wheel. Upper body configuration is represented as an anthropomimetic structure with antagonistically coupled drives. The aim of this paper is analysis of the robot behaviour under disturbances. Two types of disturbances are examined: disturbances following from the cart motion, and external disturbances. External disturbances (external impulse and long term external force emulate interaction of the robot with its environment. Numerous simulations were performed, in order to analyze the balance of the robot. Accordingly, appropriate dimensions of the mobile platform are estimated, relying on the ZMP concept. [Projekat Ministarstva nauke Republike Srbije, br. TR-35003 i br. III-44008

  1. Impact of external resistance and maximal effort on force-velocity characteristics of the knee extensors during strengthening exercise: a randomized controlled experiment.

    Science.gov (United States)

    Van Roie, Evelien; Bautmans, Ivan; Boonen, Steven; Coudyzer, Walter; Kennis, Eva; Delecluse, Christophe

    2013-04-01

    It remains controversial whether maximal effort attained by high external resistance is required to optimize muscle adaptation to strengthening exercise. Here, we compared different training protocols reaching maximal effort with either high-resistance (HImax, 80% of 1-repetition maximum [1RM]) or low-resistance (LOmax, ≤40% 1RM). Thirty-six young volunteers were randomly assigned to 9 weeks of leg extension training at either HImax (1 set of 10-12 repetitions at 80% 1RM), LO (1 set of 10-12 repetitions at 40% 1RM, no maximal effort), or LOmax (1 set of 10-12 repetitions at 40% 1RM, preceded [no rest] by 60 repetitions at 20-25% 1RM). Knee extension 1RM was measured preintervention and postintervention and before the 7th, 13th, and 19th training sessions. Preintervention and postintervention, knee extensor static (PTstat) and dynamic (PTdyn) peak torque, maximal work (MW), and speed of movement at 20% (S20), 40% (S40), and 60% (S60) of PTstat were recorded with a Biodex dynamometer. All the groups showed a significant increase in 1RM, with a greater improvement in HImax from the 13th session on (p < 0.05). The HImax was the only group that significantly increased PTstat (+7.4 ± 8.1%, p = 0.01). The LOmax showed a significantly greater increase in S20 (+6.0 ± 3.2%), PTdyn (+9.8 ± 5.6%), and MW (+15.1 ± 10.6%) than both HImax and LO (p = 0.044 for S20, p = 0.030 for PTdyn, p = 0.025 for MW) and was the only group that increased in S40 (+7.7 ± 9.7%, p = 0.032). In conclusion, significant differences between HImax and LOmax on force-velocity characteristics of the knee extensors were found, although maximal effort was achieved in both training regimens. Thus, LOmax may not be considered as a replacement for HImax but rather as an alternative with different training-specific adaptations.

  2. The main features of seasonal variability in the external forcing and dynamics of a deep mountain lake (Redó, Pyrenees

    Directory of Open Access Journals (Sweden)

    David M. LIVINGSTONE

    2000-09-01

    Full Text Available Lake Redó, a dimictic oligotrophic mountain lake, was monitored for two complete years from July 1996 to July 1998. The main seasonal variations in the physical, chemical and biological parameters are described, with special emphasis on the comparison of external forcing (weather and atmospheric deposition with internal lake dynamics. Annual mean air temperature was estimated to be 3.6 °C. The duration of ice cover on the lake was 4.5 months in 1996/97 and 5.8 months in 1997/98. The lake water was very ionpoor (mean annual conductivity 12 μS cm-1; however, ion concentrations in the lake were higher than in the precipitation, the differences being due mainly to Ca2+ and bicarbonates originating in the catchment. NH4 + was the main ion in the precipitation, with an average concentration of 17 μM, while in the lake it was always below 3 μM. However, the concentration of dissolved inorganic nitrogen always exceeded that of soluble reactive phosphorus by two or three orders of magnitude, so the latter is likely to be the limiting nutrient for phytoplankton growth. Four main production episodes were identified, occurring during spring and autumn overturn, in the upper hypolimnion during summer stratification, and under the ice at the beginning of the ice-covered period. The highest chlorophyll-a concentrations (1.2-2.2 μg l-1 were attained during spring overturn; concentrations of chlorophyll-c were high during both spring and autumn overturn, while chlorophyll-b was comparatively important in the upper hypolimnion during the stratification period. Daphnia pulicaria was the most abundant macrozooplankton species; its abundance was highest during the icecovered period, when its biomass was comparable to the measured sestonic particulate carbon concentration. The Daphnia maximum was associated with higher concentrations of NH4 + and dissolved organic carbon, suggesting that it may play an important role in the pelagic biogeochemical compartment of

  3. 双库协同机制对知识发现主流发展的驱动%The Driving Force of Double Bases Cooperating Mechanism to Knowledge Discovery Main Stream

    Institute of Scientific and Technical Information of China (English)

    周颖; 杨炳儒

    2003-01-01

    The paper, by a research report, summarizes emergence and definition of double bases cooperating mecha-nism, and introduces its driving force and influence to many sides of main stream of knowledge discovery from struc-tural model to algorithm , from structuring data mining to complex type data mining. The influence also expands tophilosophy field. It has been above five years from proposing it to now. Summarizing it makes us learn a thing clear-ly : its functions are not simply improvement to algorithm, are to bring forward many new structural models and tech-nology methods . It answers those urgent questions in the one paragraph of the paper to a greater extent. So we maysay: double bases cooperating mechanism has important driving force to main stream of knowledge discovery.

  4. 基于利益相关者理论的企业环境绩效影响因素研究%The Driving Force of Improving Coroparate Environmental Performance Based on the Stakeholder Theory

    Institute of Scientific and Technical Information of China (English)

    刘蓓蓓; 俞钦钦; 毕军; 张炳; 张永亮

    2009-01-01

    基于利益相关者理论,通过构建企业环境绩效与企业受到各利益相关者环境压力的计量模型,并在江苏常熟地区展开问卷调查,分析了影响企业环境绩效的利益相关者,结果表明:在该实证区域,以主动性环境管理行为度量企业环境绩效时,投资者、竞争者、消费者和社区居民等外部利益相关者对企业环境绩效的提高有显著的正影响;政府虽然给企业造成了很高的环境压力,但并不是造成企业之间环境绩效差异的原因;媒体和环保非政府组织等外部利益相关者作用尚不明显.结论说明:我国政府通过引入利益相关者参与企业环境治理,已经取得一定成效.建议我国政府继续推动环境政策创新,积极创造更多利益相关者成长的制度空间,为我国企业环境绩效的提高提供更多动力.%Based on the stakeholder theory, this study established an econometric model to identify the key external stakeholders that may play a role in engaging enterprises to take environmental management initiatives, and tested the hypothesis by questionnaire in Changshu city. The results indicate that investors, consumers, competitors, and local community have positive significant effects in improving corporate environmental management. Though pressure from the government is relatively high, it does not implicate positive effect on corporate environmental performance. The role of media, environmental NGOs are not significant, either. Conclusions implicate that the Chinese government has made some improvements through inducing various stakeholders to participate in corpoarate environmental governance. Suggustions are that Chinese government should keep on promoting policy innovation, exploring more institutional space for more stakeholders and providing new driving force for the improvement of corporate environmental management.

  5. Estímulos ao Desenvolvimento Tecnológico: Influência do Mercado Driving Forces for Technology Development: Market

    Directory of Open Access Journals (Sweden)

    José de A. Cid

    2002-01-01

    Full Text Available Hoje em dia não se discute mais a importância da Pesquisa e Desenvolvimento para a sobrevivência e longevidade de uma Empresa. Todo tipo de indústria sente o impacto do aumento da competição e da velocidade dos avanços tecnológicos. Entretanto, os recursos estão escassos, tanto para as despesas necessárias às atividades de negócio quanto para a pesquisa, o que deixa os gerentes com a difícil tarefa de decidir onde os recursos serão aplicados. Anos atrás, quando os recursos eram (aparentemente ilimitados a força que impulsionava a pesquisa era o desafio da descoberta do novo. A complexidade do processo, os intricados métodos de análise, a quebra de barreiras do conhecimento, alimentavam as mentes dos cientistas. Depois da pesquisa, os profissionais de marketing deveriam encontrar mercados para os novos produtos. Atualmente a pesquisa de mercado, as ferramentas de análise de negócio e outros aspectos outrora desconhecidos dos cientistas dominam as mesas dos gerentes. Este artigo descreve três diferentes abordagens na distribuição de recursos para pesquisa e resume alguns dos princípios que ajudam as empresas a funcionar melhor.Nowadays the importance of Research and Development to a Company survival and longevity is well known. Virtually every industry feels the impact of increased competition and the fast pace of technology change. However, resources are getting scarce, both for doing business and research as well, leaving managers with the tough job of selecting which project will get funding. Years ago, when money was (seemingly unlimited the driving force to research was the challenge of inventing something new. The process complexity, the intricate analysis methods, the breaking of new frontiers were the food for the scientists inquiring minds. Then marketing professionals had to work to find or create market. Now market research, business analysis tools and other aspects once unknown to scientists rule. This article

  6. Study on the Characteristics and Driving Forces of Changes of the Urban Land-Use Structure in Wuhan in 1990s%20世纪90年代武汉城市土地利用结构变动特点及动力分析

    Institute of Scientific and Technical Information of China (English)

    刘耀彬; 宋学锋

    2005-01-01

    On the basis of the information entropy and equilibrium degree of urban land-use spatial structure, the paper analyzes the characteristics and rules of urban land-use spatial structure changes in Wuhan in 1990s, in which the types of land-use are shrinking and urban land-use changes are disequilibria. With PCA and GRA employed, the driving forces have also been analyzed. The driving force of dty welfare and social structure, the towing force of city industrial structure transition, and the pressing force of city construction and reconstruction are main momentum factors. Moreover, the latter forces are more significant.

  7. Longitudinal force estimation for motorized wheels driving electric vehicle based on improved closed-loop subspace identification%基于改进闭环子空间辨识的电动轮汽车纵向力估计

    Institute of Scientific and Technical Information of China (English)

    徐兴; 陈特; 陈龙; 王吴杰

    2016-01-01

    In order to realize the control and coordinated allocation of tire longitudinal force for motorized wheels driving electric vehicle,a longitudinal force estimation method was proposed based on improved closed-loop subspace identification.The characteristics of electric drive system of motorized wheels driving vehicle was analyzed to propose a longitudinal force estimation model.The road simulation test on chassis dynamometer was carried out, and the experimental data were collected. The subspace identification algorithm N4SID was deviated when model input and noise were correlated.To solve the problem,an improved closed-loop subspace identification method was investigated.The results show that compared with N4SID identification method,the improved closed-loop subspace identification method has better anti-interference ability with higher longitudinal force estimation accuracy and better real-time tracking capability,which can meet the requirements of driving force model predictive control based on data driving.%为实现电动轮汽车轮胎纵向力的控制与协调分配,提出了基于改进闭环子空间辨识的电动轮汽车纵向力估计方法。分析了电动轮汽车电驱动系统特性,在此基础上提出了用于辨识的纵向力估计模型。进行底盘测功机道路模拟试验并采集数据。模型输入与噪声相关时,子空间 N4SID (nu-merical algorithm for subspace identification)辨识算法是有偏的,针对这一问题,研究了一种改进闭环子空间辨识算法。结果表明:对比子空间 N4SID 辨识算法,改进闭环子空间辨识算法辨识出的模型具有更好的抗干扰性,纵向力估计精度更高,实时跟踪效果更好,满足基于数据驱动的驱动力模型预测控制的需求。

  8. Drugged Driving

    Science.gov (United States)

    ... Parents & Educators Children & Teens Search Connect with NIDA : Google Plus Facebook LinkedIn Twitter YouTube Flickr RSS Menu ... misuse of prescription drugs can make driving a car unsafe—just like driving after drinking alcohol. Drugged ...

  9. An Experimental Study on the Driving System of Vibratory Feeding

    Directory of Open Access Journals (Sweden)

    Liang Han

    2013-10-01

    Full Text Available This paper describes the development of vibratory transmission system, and concentrates on its driving technology. Vibratory feeder is used to transfer parts from one place to another by vibration which plays an important role in assembly automation. Decoupled vibratory feeder (DVF is a novel feeder which can be excited in two mutual perpendicular directions. In decoupled vibratory feeder system (DVFS, vibration angle, frequency and waveform of driving signals can be easily adjusted in software way, as well as the phase angle between vertical vibration and horizontal vibration, so DVFS has a great superiority. Up to now, two DVFS prototypes have been successfully developed, but the driving technology cannot meet the demands of parts’ smooth moving. The electromagnet, the core of the drive system, should be optimized in its external dimensions and drive performance. And we fabricate a series of electromagnets. To test electromagnet performance, a test system has been designed. Presently, two researches on the electromagnet driving circuit have been made in our laboratory. One method is to receive analog signal from D/A output, then drive electromagnet through power amplifier. The other method actually is to use a switching circuit controlled by PWM technology. In this paper, we used the latter method in the test system and control system. The author makes experience about influencing factors of the electromagnetic force and gets some data. Also, the controller has greatly improved the performance of vibratory feeder.

  10. 基于BP神经网络的体外索索力预测及MATLAB实现%Prediction of the external tendons force based on BP neural network and MATLAB

    Institute of Scientific and Technical Information of China (English)

    熊辉霞; 张耀庭; 苗雨

    2011-01-01

    为了进一步研究体外预应力混凝土结构体外索极限应力的确定方法,在分析影响体外预应力混凝土结构体外索极限应力因素的基础上,运用神经网络预测的原理,采用误差反向传播神经网络即BP神经网络对体外索的索力进行了预测.预测结果表明,应用BP神经网络模型能准确的预测体外索的索力.预测结果和试验结果相比误差在10%以内,可以满足实际工程的需要.%In order to determine the maximum stress of the externally prestressed concrete structures, various factors that influence the stress were analyzed, and the theory of BP (Back Propagation) neural network was used to predict the external tendon force. The results show that the BP neural network model can predict the limit of the external tendon force and the error of the results is less than 10% compared to the experiment results, which is good enough to satisfy practical engineering needs.

  11. Electric drives

    CERN Document Server

    Boldea, Ion

    2005-01-01

    ENERGY CONVERSION IN ELECTRIC DRIVESElectric Drives: A DefinitionApplication Range of Electric DrivesEnergy Savings Pay Off RapidlyGlobal Energy Savings Through PEC DrivesMotor/Mechanical Load MatchMotion/Time Profile MatchLoad Dynamics and StabilityMultiquadrant OperationPerformance IndexesProblemsELECTRIC MOTORS FOR DRIVESElectric Drives: A Typical ConfigurationElectric Motors for DrivesDC Brush MotorsConventional AC MotorsPower Electronic Converter Dependent MotorsEnergy Conversion in Electric Motors/GeneratorsPOWER ELECTRONIC CONVERTERS (PECs) FOR DRIVESPower Electronic Switches (PESs)The

  12. The Investigation of Driving Forces of Constructing Japan and India Security System%日印安保体系构建的动力考察

    Institute of Scientific and Technical Information of China (English)

    李家成; 李昂

    2015-01-01

    Recently,the construction of Japan and India security system becomes the new norm of the coop-eration between Japan and India.Six driving forces are boosting the development of Japan and India security system:the assertive rise of China,the enticing of the United States,the rapid rise of India,the strategic ambitions of India to leverage from Japan,Japan's stiring up troubles in the Sino-Indian border dispute,the jointly guarding of Indo-Pacific maritime security by Japan and India.The new norm may help Japan and India achieve world power ambitions and America cast “Asia-Pacific rebalancing”strategy,but it will have a significant adverse impact on the China's overall national security and reshape the geopolitical situation in the Indian-Pacific region.To differentiate Japan and India security system,China should perform the two-hand strategy with striking and hooking in for India,on the one hand,reinforce and broaden the cooperation between China and India,in order to differentiate Japan and India security system;on the other hand,push the construction of China-Pakistan Economic Corridor,in order to restrict India and enhance China's strate-gic position.%近年来,日印安保体系的构建成为日印安全合作的新常态。本文总结了日印安保体系发展的六大动力,即中国的崛起促使日印积极接近、美国鼓励日印合作更上层楼、印度的崛起促使日本拉拢印度、印度的战略雄心促使印度借力日本、日本在中印边界争端上煽风点火、日印共同“护卫”印太海上安全。这一新常态虽有助于日印实现世界大国的雄心和美国施展“亚太再平衡”战略,但却会重塑印太地区的地缘政治局势,对中国总体国家安全产生重大不利影响。中国应当对印度施行打拉结合的两手策略,一方面夯实并拓宽中印合作,以分化日印安保体系;另一方面力推中巴经济走廊建设,以牵制印度并增强中国的战略地位。

  13. [Driving forces of carbon emission from energy consumption in China old industrial cities: a case study of Shenyang City, Northeast China].

    Science.gov (United States)

    Ren, Wan-Xia; Geng, Yong; Xue, Bing

    2012-10-01

    To quantitatively analyze the effects of anthropogenic factors on regional environmental quality is a hot topic in the field of sustainable development research. Taking the typical old industrial city Shenyang in Northeast China as a case, and by using the IPCC method for calculating carbon emission from energy consumption, this paper estimated the carbon emission from energy consumption in the city in 1978-2009, and a time series analysis on the anthropogenic factors driving this carbon emission was made by the STIRPAT model based upon Kaya equation and ridge regression. In 1978-2009, the carbon emission in the city had a slow increase first, slow decrease then, and a rapid increase thereafter. The total carbon emission in 2009 was 4.6 times of that in 1978. Population growth was the main factor driving the growth of the emission, and there existed an equal-proportional variation between the population growth and the carbon emission growth. Urbanization was another main driving factor followed by population growth, and the per capita GDP was positively correlated with the carbon emission. Kuznets curve did not exist for the relationship between economic development and carbon emission in Shenyang. Energy source intensity reduction (representing technology improvement) was the main factor driving the reduction of the total carbon emission.

  14. 知识管理内部驱动力与知识管理动态能力关系研究%Study on relation between knowledge management internal driving force and knowledge management dynamic apability

    Institute of Scientific and Technical Information of China (English)

    杨俊祥; 和金生

    2013-01-01

    知识经济时代,知识管理无疑是打造和增强企业技术创新能力、提高企业技术创新绩效的有效工具.知识管理是一个动态发展的过程,知识管理的成功离不开来自于企业内部多方面力量的推动.本文基于对知识管理内部驱动力以及知识管理的动态能力组成要素的研究分析,构建了知识管理内部驱动力各构成要素与知识管理动态能力各构成要素之间的作用关系模型,并做了实证验证,为我国企业有效实施知识管理提供了有益的理论建议和策略指导.%In the era of knowledge economy, it is undoubted that knowledge management is an effective tool for enterprises to create and enhance ability of technology innovation, and to improve the technology innovation performance. As a dynamic process, successful knowledge management depends on enterprise knowledge management internal driving forces. Based on study on the knowledge management internal driving force and knowledge management dynamic ability, this article constructs an interaction model between knowledge management internal driving forces and knowledge management dynamic ability, and conducts empirical testing, the study conclusion will provide a valuable theory suggestion and practice guidance for Chinese enterprises to carry out knowledge management.

  15. Relative contributions of external SST forcing and internal atmospheric variability to July-August heat waves over the Yangtze River valley

    Science.gov (United States)

    Chen, Xiaolong; Zhou, Tianjun

    2017-08-01

    The Yangtze River valley (YRV), located in central-eastern China, has witnessed increased numbers of heat waves in the summer since 1951. Knowing what factors control and affect the interannual variability of heat waves, especially distinguishing the contributions of anomalous sea surface temperature (SST) forcings and those of internal modes of variability, is important to improving heat wave prediction. After evaluating 70 members of the atmospheric model intercomparison project (AMIP) experiments from the 25 models that participated in the coupled model intercomparison project phase 5 (CMIP5), 13 high-skill members (HSMs) are selected to estimate the SST-forced variability. The results show that approximately 2/3 of the total variability of the July-August heat waves in the YRV during 1979-2008 can be attributed to anomalous SST forcings, whereas the other 1/3 are due to internal variability. Within the SST-forced component, one-half of the influence is from the impact of the El Niño-Southern Oscillation (ENSO) and the other half is from non-ENSO related SST forcings, specifically, the SST anomalies in the North Pacific and the North Atlantic. Both the decaying El Niño and developing La Niña accompanied by a warm Indian Ocean and cold central Pacific, respectively, are favorable to hotter summers in the YRV because these patterns strengthen and extend the western North Pacific Subtropical High (WNPSH) westwards, for which the decaying ENSO plays a dominant role. The internal variability shows a circumglobal teleconnection in which Rossby waves propagate southeastwards over the Eurasian Continent and strengthen the WNPSH. Atmospheric model sensitivity experiments confirm that non-ENSO SST forcings can modulate the WNPSH and heat wave variability by projecting their influences onto the internal mode.

  16. Pile Driving

    Science.gov (United States)

    1987-01-01

    Machine-oriented structural engineering firm TERA, Inc. is engaged in a project to evaluate the reliability of offshore pile driving prediction methods to eventually predict the best pile driving technique for each new offshore oil platform. Phase I Pile driving records of 48 offshore platforms including such information as blow counts, soil composition and pertinent construction details were digitized. In Phase II, pile driving records were statistically compared with current methods of prediction. Result was development of modular software, the CRIPS80 Software Design Analyzer System, that companies can use to evaluate other prediction procedures or other data bases.

  17. Exact solution of a quantum forced time-dependent harmonic oscillator

    Science.gov (United States)

    Yeon, Kyu Hwang; George, Thomas F.; Um, Chung IN

    1992-01-01

    The Schrodinger equation is used to exactly evaluate the propagator, wave function, energy expectation values, uncertainty values, and coherent state for a harmonic oscillator with a time dependent frequency and an external driving time dependent force. These quantities represent the solution of the classical equation of motion for the time dependent harmonic oscillator.

  18. Driving forces behind the increasing cardiovascular treatment intensity.A dynamic epidemiologic model of trends in Danish cardiovascular drug utilization.

    DEFF Research Database (Denmark)

    Kildemoes, Helle Wallach; Andersen, Morten

    -state (untreated, treated, dead) semi-Markov model to analyse the dynamics of drug use. Transitions were from untreated to treated (incidence), the reverse (discontinuation), and from either untreated or treated to dead. Stratified by sex and age categories, prevalence trends of "growth driving" drug categories...... were analysed, exploring trends in incidence- mortality- and discontinuation rates. Trends in prevalence proportions were estimated from logistic regression. Incidence-, discontinuation and mortality rates from Poisson regression. Results: The total cardiovascular treatment intensity increased from 285...

  19. Physical and Socioeconomic Driving Forces of Land-Use and Land-Cover Changes: A Case Study of Wuhan City, China

    Directory of Open Access Journals (Sweden)

    Xiangmei Li

    2016-01-01

    Full Text Available To investigate precise nexus between land-use and land-cover changes (LUCC and driving factors for rational urban management, we used remotely sensed images to map land use and land cover (LULC from 1990 to 2010 for four time periods using Wuhan city, China, as a case study. Partial least squares (PLS method was applied to analyze the relationships between LUCC and the driving factors, mainly focusing on three types of LULC, that is, arable land, built-up area, and water area. The results were as follows: (1 during the past two decades, the land-use pattern in Wuhan city showed dramatic change. Arable land is made up of the largest part of the total area. The increased built-up land came mainly from the conversion of arable land for the purpose of economic development. (2 Based on the Variable Importance in Projection (VIP, the joint effects of socioeconomic and physical factors on LUCC were dominant, though annual temperature, especially annual precipitation, proved to be less significant to LUCC. Population, tertiary industry proportion, and gross output value of agriculture were the most significant factors for three major types of LULC. This study could help us better understand the driving mechanism of urban LUCC and important implications for urban management.

  20. Experimental Study on the Impact of External Geometrical Shape on Free and Forced Convection Time Dependent Average Heat Transfer Coefficient during Cooling Process

    Directory of Open Access Journals (Sweden)

    Sundus Hussein Abd

    2012-01-01

    Full Text Available In this research, an experimental study was conducted to high light the impact of the exterior shape of a cylindrical body on the forced and free convection heat transfer coefficients when the body is hold in the entrance of an air duct. The impact of changing the body location within the air duct and the air speed are also demonstrated. The cylinders were manufactured with circular, triangular and square sections of copper for its high thermal conductivity with appropriate dimensions, while maintaining the surface area of all shapes to be the same. Each cylinder was heated to a certain temperature and put inside the duct at certain locations. The temperature of the cylinder was then monitored. The heat transfer coefficient were then calculated for forced convection for several Reynolds number (4555-18222.The study covered free convection impact for values of Rayleigh number ranging between (1069-3321. Imperical relationships were obtained for all cases of forced and free convection and compared with equations of circular cylindrical shapes found in literature. These imperical equations were found to be in good comparison with that of other sources.

  1. A new force emerges from the dark side: evidence is growing that an intrinsic property of the universe is helping to drive its expansion

    CERN Multimedia

    Cookson, C

    2003-01-01

    "Astronomical surveys over the past five years have forced cosmologists to conclude that ordinary matter - in the form of familiar stars, planets and interstellar dust or more exotic objects, such as quasars and neutron stars - makes up only 4 per cent of the universe" (1 page).

  2. Forces at the Main Mechanism of a Railbound Forging Manipulator

    Directory of Open Access Journals (Sweden)

    Florian Ion Tiberiu Petrescu

    2015-12-01

    Full Text Available Forging manipulators have become more prevalent in the industry today. They are used to manipulate objects to be forged. The most common forging manipulators are moving on a railway to have a greater precision and stability. They have been called the railbound forging manipulators. In this paper we determine the driving forces of the main mechanism from such manipulator. Forces diagram shows a typical forging manipulator, with the basic motions in operation process: walking, motion of the tong and buffering. The lifting mechanism consists of several parts including linkages, hydraulic drives and motion pairs. Hydraulic drives are with the lifting hydraulic cylinder, the buffer hydraulic cylinder and the leaning hydraulic cylinder, which are individually denoted by c1, c2 and c3. In this work considering that the kinematics is being solved it determines the forces of the mechanism. In the first place shall be calculated all external forces from the mechanism (The inertia forces, gravitational forces and the force of the weight of the cast part. Is then calculated all the forces from couplers. 

  3. Families of Fokker-Planck equations and the associated entropic form for a distinct steady-state probability distribution with a known external force field.

    Science.gov (United States)

    Asgarani, Somayeh

    2015-02-01

    A method of finding entropic form for a given stationary probability distribution and specified potential field is discussed, using the steady-state Fokker-Planck equation. As examples, starting with the Boltzmann and Tsallis distribution and knowing the force field, we obtain the Boltzmann-Gibbs and Tsallis entropies. Also, the associated entropy for the gamma probability distribution is found, which seems to be in the form of the gamma function. Moreover, the related Fokker-Planck equations are given for the Boltzmann, Tsallis, and gamma probability distributions.

  4. [Driving force analysis of land use change in the developed area based on Probit regression model: A case study of Nanjing City, China].

    Science.gov (United States)

    Liu, Kang; Li, Yue-e; Wu, Qun; Shen, Jian-fen

    2015-07-01

    Based on the remote sensing image in 1996, 2002 and 2010, with the help of RS and GIS technology, and using the Probit regression model, this paper analyzed the characteristics of land use change in Nanjing City from 1996 to 2010, and the driving factors of land use change. The results showed that the cultivated land and woodland decreased, constructive land, garden plot and grassland continued to increase, and the comprehensive land use change rate was rising since 1996. The results of regression model for cultivated land and woodland change indicated that the change of cultivated land in the years 1996-2002 was mainly affected by the factors of "distance to the nearest rural settlement" and "farmers' population density". However, in the years 2002-2010 it was mainly affected by the factors of "change of per area GDP", "distance to the rural settlement" and "distance to the nearest road". The change of woodland in the years 1996-2002 was mainly affected by the factors of "the elevation" and "distance to the rural settlement". However, in the years 2002-2010 it was mainly affected by the factors of "change of per area GDP", "population density" and "distance to the nearest road". By comparison, the early driving factors of land use change were mainly natural factors, but in recent years, they were mainly social, economic and demographic factors.

  5. Distracted Driving

    Science.gov (United States)

    ... What's this? Submit What's this? Submit Button Distracted Driving Recommend on Facebook Tweet Share Compartir Each day in the United States, over 8 people are killed and 1,161 injured in crashes ...

  6. DRIVING GREEN

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    China is promoting environmentally friendly cars to save energy and protect the environment While people enjoy the pleasure and convenience of driving, they are also creating and breathing more and more toxic

  7. Enhancement of wave and acceleration of electron in plasma in the external field

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper investigates the enhancement of Langmuir and ion-acoustic wave and the acceleration of the electron in collisionless plasma.in the presence of an external transverse field.Based on hydrodynamic equations,an equation formulizing the parametric instability was derived.Furthermore,the formula for ponderomotive force and the expression that describes the electron acceleration were obtained.The results show that Langmuir and ion-acoustic wave are enhanced and the charged particles can be accelerated by the coupling of wave-wave.In addition,it can be concluded that ponderomotive force,due to the coupling of the external field(pump)to the Langmuir wave(ion-acoustic wave),is the driving force to excite the parametric instability and comprises the high- and low-frequency components.

  8. 我国现阶段土地利用变化驱动力的宏观分析%Macro-analysis on the driving forces of the land-use change in China

    Institute of Scientific and Technical Information of China (English)

    李平; 李秀彬; 刘学军

    2001-01-01

    Land-use is one complex system, which is affected by many factors, including both socio-economic elements and natural resources and environment. This paper firstly established a framework for macro-analysis on the driving forces of land-use change in China, in which economic welfare, environmental welfare, the need for food security and the advancement of science and technology are the main forces contributing to the land-use changes. Then the paper analyzed the basic contradictions in the land-use change in recent years on the basis of current situation of land-use and economic development in China. In the third section, according to the analytical framework established firstly and the basic contradictions in the land-use change, and on the basis of the land-use data and other related socio economic documents in recent years, this paper analyzed and computed the indexes of the driving forces of the land-use change and represented their spatial distribution in China. By the distribution of these driving forces, the whole China can be seen as three distinct sub-areas: Tibet-southwest sub-area, central-northwest sub-area and east sub-area, each of which takes on different features in respect of the driving forces of land-use changes. As indicated in this paper, the economic welfare is the fundamental impetus to the land-use changes, and the environmental welfare and the need for food security are also important factors in China. The future land-use change is ultimately decided by the performance of these factors and their interactions.%土地利用的基本竞争模型是土地利用类型变化驱动力分析的理论基础。把握土地利用个体目标和社会目标的关系,尤其是它们之间的矛盾及其地区差异,是进行土地利用变化驱动力宏观分析的有效途径。工业化城市化与粮食安全之间的矛盾、农业发展与生态环境保护之间的矛盾是现阶段我国土地利用变化的基本矛盾。土地利用变化

  9. Analysis of application about driving circuit of external load switch in single-phase smart meter based on the magnetic latching relay%基于磁保持继电器的单相智能电能表外接负荷开关应用分析

    Institute of Scientific and Technical Information of China (English)

    马利人; 甘依依

    2013-01-01

    介绍单相智能电能表外控技术要求和磁保持继电器技术特点,详述了磁保持继电器有源隔离驱动电路的工作原理,分析了外置开关的通断状态检测的实用方法,并指出了单相智能电能表技术规范应补充的具体内容.%To introduces the technology requirements of the external control about single - phase smart meter and technical characteristics of magnetic latching relay, details the working principle about the active - isolated driving circuit of the latching relay, analyzes the practical methods about the detection of external switching condition, and pointed out the specific content should be added to technical specifications of single - phase smart meter.

  10. Biogeochemistry and ecosystems of continental margins in the western North Pacific Ocean and their interactions and responses to external forcing - an overview and synthesis

    Science.gov (United States)

    Liu, K.-K.; Kang, C.-K.; Kobari, T.; Liu, H.; Rabouille, C.; Fennel, K.

    2014-12-01

    In this special issue we examine the biogeochemical conditions and marine ecosystems in the major marginal seas of the western North Pacific Ocean, namely, the East China Sea, the Japan/East Sea to its north and the South China Sea to its south. They are all subject to strong climate forcing as well as anthropogenic impacts. On the one hand, continental margins in this region are bordered by the world's most densely populated coastal communities and receive tremendous amount of land-derived materials. On the other hand, the Kuroshio, the strong western boundary current of the North Pacific Ocean, which is modulated by climate oscillation, exerts strong influences over all three marginal seas. Because these continental margins sustain arguably some of the most productive marine ecosystems in the world, changes in these stressed ecosystems may threaten the livelihood of a large population of humans. This special issue reports the latest observations of the biogeochemical conditions and ecosystem functions in the three marginal seas. The studies exemplify the many faceted ecosystem functions and biogeochemical expressions, but they reveal only a few long-term trends mainly due to lack of sufficiently long records of well-designed observations. It is critical to develop and sustain time series observations in order to detect biogeochemical changes and ecosystem responses in continental margins and to attribute the causes for better management of the environment and resources in these marginal seas.

  11. 鄱阳湖退化芦苇湿地驱动因子分析%Analysis on the driving forces of the degraded Phragmites australis wetlands in Poyang Lake

    Institute of Scientific and Technical Information of China (English)

    周莉荫; 李勇; 任琼

    2015-01-01

    以鄱阳湖退化芦苇湿地为研究对象,综合考虑自然和人为因素,探求芦苇湿地退化的驱动力. 呼吁加强湿地植物资源管理及有效利用,保护人类赖以生存与发展的湿地资源.%In this paper, degraded Phragmites australis wetland in Poyang Lake was took as study object, natural and human factors were comprehensively considered to explore the driving force of the degradation of Ph. australis wetland. It was calling for strengthening the management and effective utilization of wetland plant resources and protecting the wetland resources for human survival and development.

  12. 制造企业服务化--驱动力、模式、路径和绩效研究综述%A Review on Driving Forces, Modes, Paths and Performance of Servitization in Manufacturing Enterprises

    Institute of Scientific and Technical Information of China (English)

    高文军; 陈静; 陈菊红

    2016-01-01

    Servitization has become a hotspot of scholars at home and abroad. It reviews driving forces, modes, paths and performance of servitization in manufacturing enterprises on the base of summarizing its concept from the views of conversion process and phenomenon. It also proposes the future research framework and content in accordance with the existing deficiencies.%制造企业服务化已成为国内外学者研究的热点问题。在从转化过程和现象两个视角对制造企业服务化概念进行概述的基础上,综述了制造企业服务化的驱动力、模式、路径和绩效;基于已有研究的不足,给出了未来进一步研究的框架和内容。

  13. A contrast of two typical LUCC processes and their driving forces in oases of arid areas: A case study of Sangong River Watershed at the northern foot of Tianshan Mountains

    Institute of Scientific and Technical Information of China (English)

    TANG FaShu; CHEN Xi; LUO GePing; LIN Qing; LIU HaiLong

    2007-01-01

    Aerial photographs taken in 1978 and 1987, Landsat TM images in 1998 as well as soil, hydrology and socio-economic data for the oases in Sangong River Watershed were processed by Remote Sensing (RS) and Geographic Information System (GIS). There are two typical agricultural land uses in oases,Farm-based Land Use with large-scale intensified agricultural activities (FLU) and Household Responsibility-based Land Use with small-scale activities (HRLU). The Index Model of Land Use/Land Cover Change (LUCC), Weighted Index Sum (WIS) and logistic stepwise regression model were established to contrast the two typical LUCC processes and their driving forces. The land use patterns were dominated by cropland and grassland for the entire region, and cropland, residential and industrial land were increasing stably. In the HRLU areas, woodland and grassland declined dramatically, but in the FLU areas, grassland decreased only by 12.0%, whereas woodland increased by 13.7%. LUCC was stronger in the earlier stage (1978-1987) than in the later stage (1987-1998) for the entire region. LUCC was more intense in the HRLU areas than in the FLU areas during the entire period (1978-1998). Policy was a key factor in the land use change, and water resources were a precondition in land use. Under the control of policy and water resources,the main human driving factors included population and economy, and the main natural restrictions were soil fertility and groundwater depth. Human driving factors controlled the land change in the HRLU areas, but natural restriction factors dominated in the FLU areas. In the mean time,intensification of LUCC in the region had some spatiotemporal implications with a fluctuation of impact factors.

  14. Offset Compound Gear Drive

    Science.gov (United States)

    Stevens, Mark A.; Handschuh, Robert F.; Lewicki, David G.

    2010-01-01

    The Offset Compound Gear Drive is an in-line, discrete, two-speed device utilizing a special offset compound gear that has both an internal tooth configuration on the input end and external tooth configuration on the output end, thus allowing it to mesh in series, simultaneously, with both a smaller external tooth input gear and a larger internal tooth output gear. This unique geometry and offset axis permits the compound gear to mesh with the smaller diameter input gear and the larger diameter output gear, both of which are on the same central, or primary, centerline. This configuration results in a compact in-line reduction gear set consisting of fewer gears and bearings than a conventional planetary gear train. Switching between the two output ratios is accomplished through a main control clutch and sprag. Power flow to the above is transmitted through concentric power paths. Low-speed operation is accomplished in two meshes. For the purpose of illustrating the low-speed output operation, the following example pitch diameters are given. A 5.0 pitch diameter (PD) input gear to 7.50 PD (internal tooth) intermediate gear (0.667 reduction mesh), and a 7.50 PD (external tooth) intermediate gear to a 10.00 PD output gear (0.750 reduction mesh). Note that it is not required that the intermediate gears on the offset axis be of the same diameter. For this example, the resultant low-speed ratio is 2:1 (output speed = 0.500; product of stage one 0.667 reduction and stage two 0.750 stage reduction). The design is not restricted to the example pitch diameters, or output ratio. From the output gear, power is transmitted through a hollow drive shaft, which, in turn, drives a sprag during which time the main clutch is disengaged.

  15. 1980-2012年村域居民点演变特征及其驱动力分析%Evolution characteristics and its driving force of rural residential land at village level during 1980-2012

    Institute of Scientific and Technical Information of China (English)

    冯应斌; 杨庆媛

    2016-01-01

    Appraisal. Based on rural residential land evolution process at spatial and time dimensions and its characteristics in Guni village of Chongqing in resent 30 years since 1980, we analyzed evolution characteristics of rural residential land scale, space form, structure system and landscape pattern at village level, and summed up general rule of rural residential land evolution in space and time dimensions. The results showed that rural residential land area in Guni village was 22.79 hm2in 1980, and increased to 33.47 hm2in 2012. The average annual growth reached 1.21%. Rural residential land patch had been in a central tendency at time dimension, and expansion rate of rural residential land experienced a process from pure extension to coexistence of expansion and tightening. Rural residential land patch was in an irregular shape, which was departed from circular and square at spatial and time dimensions. The spatial structure of rural residential land presented an evolution tendency from relatively centralized to comparatively decentralized, while spatial structure system of main settlements had an acute evolution with unreasonable grade. The landscape diversity of rural residential land patch and its uniform distribution degree had a further improvement at village level, but the landscape heterogeneity had been further stood out at group level. Leading factors (total population, quantity of labor force and peasant household) could promote the expansion of rural residential land scale. However, its influence had a downward trend with time scale. Economic development level factors such as average income were inducement factors, and its driving force had further strengthened with time. Locations along the highway were one of the leading driving forces of newly-added rural residential land expansion, and the expansion of rural residential land since 2005 had been the result of new rural reconstruction policy-driven. Based on driving force model of rural residential land

  16. Defensive externality and blame projection following failure.

    Science.gov (United States)

    Hochreich, D J

    1975-09-01

    This study focuses upon the relationship between internal-external control and defensive blame projection. Trust was used as a moderator variable for making differential predictions concerning the behavior of two subgroups of externals: defensive externals, whose externality is presumed to reflect primarily a verbal technique of defense, and congruent externals, whose externality reflects a more genuine belief that most outcomes are determined by forces beyond their personal control. As predicted, defensive externals showed a stronger tendency than did congruent externals and internals to resort to blame projection following failure at an achievement task. There were no group differences in attribution following task success. Defensive externals were found to be more responsive to negative feedback than were congruent externals.

  17. Death Drive

    OpenAIRE

    Stühler, Rebekka Hellstrøm

    2012-01-01

    The aim of this project is to investigate why the Freudian term Death Drive is not acknowledged in modern psychological therapy. On basis of psychoanalytical theory and through a literary analysis, the project will present a discussion of the significance and presence of the term within these practises.

  18. Containment atmosphere response to external sprays

    Energy Technology Data Exchange (ETDEWEB)

    Green, J.; Almenas, K. [Univ. of Maryland, College Park, MD (United States)

    1995-09-01

    The application of external sprays to a containment steel shell can be an effective energy removal method and has been proposed in the passive AP-600 design. Reduction of the steel shell temperature in contact with the containment atmosphere enhances both heat and mass transfer driving forces. Large scale experimental data in this area is scarce, therefore the measurements obtained from the E series tests conducted at the German HDR facility deserve special attention. These long term tests simulated various severe accident conditions, including external spraying of the hemispherical steel shell. This investigation focuses upon the integral response of the HDR containment atmosphere during spray periods and upon methods by which lumped parameter system codes, like CONTAIN, model the underlying condensation phenomena. Increases in spray water flowrates above a minimum value were ineffective at improving containment pressure reduction since the limiting resistance for energy transfer lies in the noncondensable-vapor boundary layer at the inner condensing surface. The spray created an unstable condition by cooling the upper layers of a heated atmosphere and thus inducing global natural circulation flows in the facility and subsequently, abrupt changes in lighter-than-air noncondensable (J{sub 2}/He) concentrations. Modeling results using the CONTAIN code are outlined and code limitations are delineated.

  19. Empirical Evaluation On External Debt Of Malaysia

    OpenAIRE

    Nor’Aznin Abu Bakar; Sallahuddin Hassan

    2011-01-01

    This study analyzes the effects of external debts on economic growth in Malaysia. The analysis is conducted both at aggregate and disaggregate levels. The empirical results are based on VAR estimates using GDP, external debts, capital accumulation, labor force and human capital. Estimation results at the aggregate level indicate that total external debts affect economic growth positively. In particular, one percentage point increase in total external debts generates 1.29 percentage point of e...

  20. Vegetation dynamics and its driving forces from climate change and human activities in the Three-River Source Region, China from 1982 to 2012

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ying; Zhang, Chaobin; Wang, Zhaoqi; Chen, Yizhao; Gang, Chengcheng [School of Life Science, Nanjing University, Xianlin Road 163, Qixia District, Nanjing, 210046 (China); An, Ru [School of Earth Science and Engineering, Hohai University, Xikang Road 129, Nanjing, 210098 (China); Li, Jianlong, E-mail: lijianlongnju@163.com [School of Life Science, Nanjing University, Xianlin Road 163, Qixia District, Nanjing, 210046 (China)

    2016-09-01

    The Three-River Source Region (TRSR), a region with key importance to the ecological security of China, has undergone climate changes and a shift in human activities driven by a series of ecological restoration projects in recent decades. To reveal the spatiotemporal dynamics of vegetation dynamics and calculate the contributions of driving factors in the TRSR across different periods from 1982 to 2012, net primary productivity (NPP) estimated using the Carnegie–Ames–Stanford approach model was used to assess the status of vegetation. The actual effects of different climatic variation trends on interannual variation in NPP were analyzed. Furthermore, the relationships of NPP with different climate factors and human activities were analyzed quantitatively. Results showed the following: from 1982 to 2012, the average NPP in the study area was 187.37 g cm{sup −2} yr{sup −1}. The average NPP exhibited a fluctuation but presented a generally increasing trend over the 31-year study period, with an increase rate of 1.31 g cm{sup −2} yr{sup −2}. During the entire study period, the average contributions of temperature, precipitation, and solar radiation to NPP interannual variation over the entire region were 0.58, 0.73, and 0.09 g cm{sup −2} yr{sup −2}, respectively. Radiation was the climate factor with the greatest influence on NPP interannual variation. The factor that restricted NPP increase changed from temperature and radiation to precipitation. The average contributions of climate change and human activities to NPP interannual variation were 1.40 g cm{sup −2} yr{sup −2} and − 0.08 g cm{sup −2} yr{sup −2}, respectively. From 1982 to 2000, the general climate conditions were favorable to vegetation recovery, whereas human activities had a weaker negative impact on vegetation growth. From 2001 to 2012, climate conditions began to have a negative impact on vegetation growth, whereas human activities made a favorable impact on vegetation

  1. Driving Mechanism Study on Rural Labour Force's Transference Under the City and Countryside Overall Plan%城乡统筹视角下农村劳动力转移驱动机理研究

    Institute of Scientific and Technical Information of China (English)

    石永明; 邱道持; 骆东奇

    2011-01-01

    农村劳动力转移对促进社会主义新农村建设、解决“三农”问题意义重大.本文以重庆市璧山县为例,在对2个街办3个乡镇150余农户抽样调查基础上分析了该地区农村劳动力转移的经济学、土地流转、心理学和社会学方面的驱动机理,并提出加快农村劳动力转移需完善保障机制、发展现代农业、加快城镇建设等一系列建议.%Rural Labour Force's Transference has big sense in promoting the socialistic new rural construction and resolving the "countryside-agriculture-farmer" problems. On the census data from more than 150 rural families (mainly is egress work) and more than 150 peasant laborer being out of 3 towns and 2 sub-district offices in the Chongqing Municipality's Bishan County, this paper has analyzed its economic, psychological and land circulation and sociological driving mechanism, and proposed to consummate the safeguard mechanism, to develop modern agriculture, to develop the town construction and so on a series of suggestions for speeding up the Rural Labour Force's Transference.

  2. Drive integration challenges for perpendicular recording

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, S.E.; Lairson, B.M.; Nguy, Hai; Nguyen, Linda; Huang, Ton; Adler, Jason; Gopalaswamy, Srini

    2001-10-01

    Integration of heads and media for perpendicular recording into disk drives will require new developments in several areas. This paper discusses the methods we use to characterize error rate and servo performance of perpendicular recording components, and highlights the impact of skew angle and external field on recording performance. We also report our first efforts to incorporate perpendicular components into disk drives.

  3. A study on AB{sub 2}O{sub 6} compounds. Pt. V. A DFT study on charge balance as driving force for structural organisation

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Horst P. [Saarbruecken Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2015-11-01

    In continuation of earlier investigations on the structures of AB{sub 2}O{sub 6} compounds we have remodelled those with A=Ca, Sr, Ba and B=As, Sb, V, Nb, Ta by relaxation in DFT calculations with the VASP code. The results match the real structures very closely. We have then calculated charges of the constituent atoms by means of a Bader analysis of the calculated electron density distribution. The results of these calculations are discussed with the aim to establish a correlation between the charges of the atoms and the vicinity structure around the atoms. Similar calculations were done first for all these compounds in a rosiaite type structure and second for CaAs{sub 2}O{sub 6} in all the other structures found for these compounds. We discuss how the balance of charges changes on forcing the systems into another topology, and we finally address the issue that structural organisation is strongly determined by the need to balance charges of the constituting elements in their specific stoichiometric relation.

  4. Driving-force compensation to improve the bias thermal stability of MEMS gyroscopes%改善MEMS陀螺误差温度稳定性的驱动力补偿方法

    Institute of Scientific and Technical Information of China (English)

    刘宇航; 陈志勇; 张嵘

    2013-01-01

    由于微机电系统(MEMS)陀螺通常采用微加工工艺生产制造,因此总是受微加工过程带来的的各种精度缺陷影响.对于MEMS陀螺,其零位输出误差因受环境因素影响而无法保持稳定,随时间表现出漂移特性,这种特性严重限制了MEMS陀螺在更高精度应用中的可用性.该文研究了一种改善MEMS陀螺零位误差温度稳定性的方法.通过分析陀螺运动特性及主要误差源,阐明陀螺驱动力对检测方向的耦合作用是零偏误差同相分量产生并随温度漂移的主要原因之一.为抑制陀螺驱动力耦合作用,提出对陀螺检测轴施加补偿静电力的方法.温度试验结果表明:施加补偿作用后,陀螺零偏误差同相分量的温度稳定性在12~60℃范围内提高了3倍以上.%Micro electro mechanical system (MEMS) gyroscopes can be manufactured using micro-machining procedures,but they are all subject to unavoidable defects related to the fabrication processes.The zero-rate output (ZRO) of a MEMS gyroscope is known to vary with the environment which severely restricts high-precision applications.This paper presents a method to improve MEMS gyroscope thermal stability during temperature variations.Analysis of the gyro's error sources and fundamental dynamics show that the coupling of driving forces has a crucial effect on the in phase ZRO and also contributes to the instabilities of the gyro's bias.The coupling of the gyro driving forces can be suppressed by electrostatic force compensation applied to the sensing axis with temperature tests showing that the gyro bias is three times more stable after compensation for temperatures of 12 ~ 60℃.

  5. A high force of plasmodium vivax blood-stage infection drives the rapid acquisition of immunity in papua new guinean children.

    Directory of Open Access Journals (Sweden)

    Cristian Koepfli

    Full Text Available BACKGROUND: When both parasite species are co-endemic, Plasmodium vivax incidence peaks in younger children compared to P. falciparum. To identify differences in the number of blood stage infections of these species and its potential link to acquisition of immunity, we have estimated the molecular force of blood-stage infection of P. vivax ((molFOB, i.e. the number of genetically distinct blood-stage infections over time, and compared it to previously reported values for P. falciparum. METHODS: P. vivax (molFOB was estimated by high resolution genotyping parasites in samples collected over 16 months in a cohort of 264 Papua New Guinean children living in an area highly endemic for P. falciparum and P. vivax. In this cohort, P. vivax episodes decreased three-fold over the age range of 1-4.5 years. RESULTS: On average, children acquired 14.0 new P. vivax blood-stage clones/child/year-at-risk. While the incidence of clinical P. vivax illness was strongly associated with mol FOB (incidence rate ratio (IRR = 1.99, 95% confidence interval (CI95 [1.80, 2.19], (molFOB did not change with age. The incidence of P. vivax showed a faster decrease with age in children with high (IRR = 0.49, CI95 [0.38, 0.64] p<0.001 compared to those with low exposure (IRR = 0.63, CI95[0.43, 0.93] p = 0.02. CONCLUSION: P. vivax (molFOB is considerably higher than P. falciparum (molFOB (5.5 clones/child/year-at-risk. The high number of P. vivax clones that infect children in early childhood contribute to the rapid acquisition of immunity against clinical P. vivax malaria.

  6. 微陀螺梳齿静电驱动力的计算方法%The Calculation Method of the Electrostatic Drive Force of Micro Machined Groscope Comb

    Institute of Scientific and Technical Information of China (English)

    姚峰林; 高世桥

    2011-01-01

    To calculate the electrostatic force in the micro machined gyroscope is a key problem in the mechanical characteristic of it. Base on the principle of electrostatic drive of the micro machined gyroscope, the paper introduces infinite plane model, edge-effect model and comer-effect model as the electrostatic field computation module of the micro comb. It deduces the formula of capacitance computation and electrostatic force of three models. By the numerical calculation and finite element calculation, it gets the capacitance and the electrostatic force of the gyroscope and the applicable circumstance of each model that the overlap length in variation. It suggests that the edge-effect and the corner-effect of comb should be fully considered when designing and computing the comb.%准确计算静电力是分析微机械陀螺力学特性的关键.文章基于微陀螺静电驱动原理,介绍了微梳齿结构的静电场计算的无限大平板模型,边缘效应模型,拐角效应模型三种模型.推导了三种模型的电容计算公式和静电力计算公式.通过数值计算和有限元计算,得到交叠长度变化时,不同计算模型的电容和静电驱动力的对比和各种模型的适用范围.说明在微尺度条件下静电场的边缘效应和拐角效应应当在设计和计算梳齿时应当充分考虑.

  7. 冷轧机附加倾斜后双侧非对称轧制力的计算%Asymmetric Roll Force Calculation With Additional Tilt for Drive Side and Operator Side of Cold Strip Mill

    Institute of Scientific and Technical Information of China (English)

    刘宝权; 张鸿; 王自东; 王军生; 张岩

    2011-01-01

    对冷轧带钢轧制过程中因辊缝倾斜调整过量所导致的单边浪缺陷和断带进行了分析,应用影响函数法计算辊系变形,通过迭代计算出附加倾斜后的传动侧轧制力、操作侧轧制力、辊间压力分布、单位宽度轧制力分布、出口厚度横向分布、出口横向张应力分布。理论计算和实际测量结果表明,冷轧机双侧轧制力差值与倾斜调整量呈近似线性增长的规律。根据轧制力差值与倾斜量之间的比例关系,用实测轧制力差值对倾斜值进行动态限幅,可有效避免冷轧过程中断带事故的发生。%The single edge wave and strip break caused by excessive tilting adjustment were analyzed. Influence func tion method was adopted to model the roll deformation. Adding different tilt, roll force of drive side, roll force of operator side, transverse distribution of contact pressure between rolls, transverse distribution of roll force, trans verse distribution of strip thickness at exit side and transverse distribution of tension at exit side were calculated by using iterative method. The theoretical calculation and the actual measurement results show that the difference be- tween the bilateral increases almost linearly with tilt adjustment value. The break strip accidents are effectively aver ted by dynamic limiting to tilt setting value with the measured differential roll force, according to the proportional relationship between the differential roll force and the tilt.

  8. 基于外加驱动场的相干调控来增强古斯—汉欣位移%Enhancement of Goos-Hnchen Shift by Coherent Control Based on External Drive Field

    Institute of Scientific and Technical Information of China (English)

    邓文武

    2011-01-01

    he manipulation of the Goos-Hnchen shifts in the reflected and transmitted light beam through a cavity containing two-level atomic medium,via two external coherent control field,by modifying the dispersion-absorption properties of the intracavity medium,the lateral shifts of the reflected and transmitted beams can be easily controlled by adjusting detuning of the external control field.And the lateral shifts can be enhanced in weak amplification region.%通过外加驱动场来调控腔中二能级介质的吸收-色散关系来调控反射光和透射光的古斯-汉欣位移。研究表明,在弱放大区域附近对古斯-汉欣位移的控制比强吸收或强放大特性下要灵敏,可以实现位移的突变和增强。

  9. STUDY ON THE SPATIAL PATTERNS OF LAND-USE CHANGE AND ANALYSES OF DRIVING FORCES IN NORTHEASTERN CHINA DURING 1990-2000

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Land-use change is an important aspect of global environment change. It is, in a sense, the direct resultof human activities influencing our physical environment. Supported by the dynamic serving system of national resources,including both the environment database and GIS technology, this paper analyzed the land-use change in northeastern Chi-na in the past ten years (1990 -2000). It divides northeastern China into five land-use zones based on the dynamic de-gree (DD) of land-use: woodland/grassland - arable land conversion zone, dry land - paddy field conversion zone, ur-ban expansion zone, interlocked zone of farming and pasturing, and reclamation and abandoned zone. In the past tenyears, land-use change of northeastern China can be generalized as follows: increase of cropland area was obvious, pad-dy field and dry land increased by 74. 9 and 276. 0 thousand ha respectively; urban area expanded rapidly, area of townand rural residence increased by 76. 8 thousand ha; area of forest and grassland decreased sharply with the amount of1399. 0 and 1521.3 thousand ha respectively; area of water body and unused land increased by 148.4 and 513.9 thou-sand ha respectively. Besides a comprehensive analysis of the spatial patterns of land use, this paper also discusses thedriving forces in each land-use dynamic zones. The study shows that some key biophysical factors affect conspicuously theconversion of different land-use types. In this paper, the relationships between land-use conversion and DEM, accumulat-ed temperature(≥10℃) and precipitation were analysed and represented. We conclude that the land-use changes in north-east China resulted from the change of macro social and economic factors and local physical elements. Rapid populationgrowth and management changes, in some sense, can explain the shaping of woodland/grassland-cropland conversionzone. The conversion from dry land to paddy field in the dry land - paddy field conversion zone, apart from the

  10. POMDP-based Planning Model of Driving Force during Shield Tunneling%基于部分可观测Markov决策过程理论的盾构推进载荷规划

    Institute of Scientific and Technical Information of China (English)

    胡祥涛; 张红旗; 李自成; 黄永安

    2014-01-01

    针对盾构掘进过程中位姿控制问题,提出了基于部分可观测马尔科夫决策过程(Partially observable Markov decision processes, POMDP)理论的推进载荷规划方法。在推进载荷规划模型中,将盾构自动纠偏看成不确定环境下序贯决策问题,充分考虑掘进过程中随机因素的影响,将盾构掘进过程中受到的阻力、推进载荷和盾构位姿分别定义为POMDP的状态集、行动集和观测集,然后重点讨论了信念状态、状态转移函数和观测函数等几个关键参数的获取方法。在计算值函数时,考虑了盾构位姿偏离程度和盾构载荷平稳程度对推进载荷决策的影响,建立了立即收益函数和长期折扣收益函数,并采用基于点的值迭代算法寻求推进载荷最优规划策略。针对天津地铁9号线进行了案例分析,结果表明基于POMDP的推进载荷规划方法是合理有效的,能够顺应掘进阻力随机变化。%In shield tunneling, the automatic control systems are mostly based on empirical relationships and do not have a precise theoretical background. Consequently, the present automatic control systems control the shield according to a snake-like motion to move it back onto the planned alignment. To solve such problems, an approach that adopts partially observable Markov decision processes (POMDP) theory to plan the driving force with explicit representation of the uncertainty during excavation is presented. In POMDP, the huge resistances during excavation, shield attitudes, and the driving force of possible world are scattered as the state set, observe set and action set, respectively. Furthermore, the deviations of shield attitude from planned alignment and the stationary of the loads acting on the shield are considered in the calculation of the value function. The experimental results confirm that the driving force planning based on POMDP is reasonable, and have certain ability of compliance at the

  11. LAND USE AND ITS DRIVING FORCES AT VILLAGE SCALE IN NUJIANG RIVER WATERSHED OF NORTHERN YUNNAN%怒江云南北段的村域土地利用及驱动力分析

    Institute of Scientific and Technical Information of China (English)

    赵莉莉; 杨文忠; 孟广涛; 范勋承

    2012-01-01

    Driving forces analysis is imperative in the study of land-use/cover changes (LUCC). We carried out a study on LUCC and its driving forces at village scale. Study pilots were 4 communities adjacent to the Gaoligongshan Nature Reserve in Nujiang River watershed of Northern Yunnan. SPOT-5 remote sensing images combining with field investigation were used to classify land use types and create classification system. Land use patterns and characteristics at village scale were analyzed by using Fragstats 3. 3. Meanwhile, socioeconomic data were obtained through household survey, semi-structure interviewing, and questionnaires. Relationship between land use pattern and socioeconomic status was built to analyze driving forces of LUCC. Results showed that land use was driven mainly by natural conditions,villagers' education level, and social customs. At the same time, households' cash incomes depended strongly upon extensive land uses. Study results provide quantified information for land resource management and village economic development in Nujiang River Watershed of Northern Yunnan. Methods we adopt can be used as a reference for LUCC studies at local scale.%驱动力分析是土地利用研究的重要内容。选择怒江流域北段高黎贡山自然保护区周边4个自然村为研究对象,应用高分辨率SPOT-5遥感影像数据,结合实地逐块核实,对土地利用/覆被进行分类,并建立土地利用类型分类系统,用Fragstats 3.3分析得到村域土地利用格局和特征;同时,采用入户调查、半结构访谈和问卷调查等方法,获得的村域详细社会经济数据,建立土地利用与社会经济之间的关联,分析村域土地利用的驱动力。结果显示:村域土地利用主要受自然条件、受教育程度、生活习俗等因子的驱动,且经济收入主要依赖于粗放的土地利用。研究结果能为怒江云南北段的土地资源合理利用和村域经济发展提供数据支持;研究方法

  12. LAND USE CHANGE AND ITS SOCIO-ECONOMIC DRIVING FORCES UNDER STRESS OF PROJECT IN OLD RESERVOIR AREA --Case Study of Linshui Reservoir Area of Dahonghe Reservoir in Sichuan Province

    Institute of Scientific and Technical Information of China (English)

    SHAO Jin-gan; HUANG Xue-qin; QU Ming; WEI Chao-fu; XIE De-ti

    2005-01-01

    The old reservoir areas built in 1950s-1970s left behind many socio-economic problems, because of the administrative backward migration and little migration fund, and all these problems would be tied to land. Based on interviewing with peasant households, combining land use survey and socio-economic statistical index, this paper analyzed land use change and its corresponding driving forces in Linshui reservoir area of Dahonghe Reservoir. Results showed that land use change in the reservoir area was mainly embodied on low-lying land submergence and migration requisition land. The former changed the land use patterns, and the latter mainly reconstructed original land property and made land over-fragmented. Cultivated land per capita was 0.041ha in this area, below the cordon of cultivated land per capita enacted by FAO. Currently, there were still 30.25% of peasant households being short of grain in trimester of one year, and there were 35.27% of people living under the poverty line. The conditions of eco-environment in Linshui Reservoir Area were worse, and healthy and sub-healthy eco-environment accounted for less proportion, composed of green belt around the reservoir area and paddy field ecosystem, and economic forest and orchard ecosystem, respectively. The stress of the reservoir project was macroscopic background to analyze the driving factors of land use change, and real underlying diving factor of the land use change in the area was the change of cultural landscape under the stress of reservoir project. The rapid increase of population was the key factor to induce the change of man-land relationship in the reservoir area, the low level of rural economy was the crucial factor to decide how migrants input for production, and the belief of migrants, influencing the land use patterns in a certain extent, was the inducing factor to keep land use stable. The low-lying submergence and infrastructure construction accompanied the reservoir project were leading

  13. Directed motion generated by heat bath nonlinearly driven by external noise

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhuri, J Ray [Department of Physics, Katwa College, Katwa, Burdwan 713 130, West Bengal (India); Barik, D [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Banik, S K [Department of Physics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0435 (United States)

    2007-12-07

    Based on the heat bath system approach where the bath is nonlinearly modulated by an external Gaussian random force, we propose a new microscopic model to study directed motion in the overdamped limit for a nonequilibrium open system. Making use of the coupling between the heat bath and the external modulation as a small perturbation, we construct a Langevin equation with multiplicative noise- and space-dependent dissipation and the corresponding Fokker-Planck-Smoluchowski equation in the overdamped limit. We examine the thermodynamic consistency condition and explore the possibility of observing a phase-induced current as a consequence of state-dependent diffusion and, necessarily, nonlinear driving of the heat bath by the external noise.

  14. 新疆博州地区土地利用变化及驱动力分析%Analysis of Land Use/Cover Change and Driving Force on Bo Zhou of Xinjiang Province Zone

    Institute of Scientific and Technical Information of China (English)

    杜倩; 王勇辉

    2012-01-01

    The land use structure and the quality of land resource change constantly, because ot the natural factors and human factors, which results in the variation of the regional ecological environment and global environment. This article used the data of the land utilization in BoZhou of Xinjiang province from 2001 to 2009 to analyze its dynamic change. The conclusion is that farmland and land for household, industry, traffic and water conservancy facilities have increased in varying changes, while garden and grassland area have decreased. Afterwards, the social driving forces of the variation of land area in BoZhou were ana- lyzed quantitatively by analyzing the related data of social economy development, by the means of principal component analysis. We concluded that the adjustment of agricultural structure, economic development, production benefit, political and economic policies are main social driving forces causing variation of land u- tilization and the first industry is still in a dominant position.%由于受自然因素与人文因素的影响,土地利用结构以及土地资源质量不断变化,从而引起区域生态环境和全球环境的变化。文章运用新疆博州2000--2009年土地利用数据,分析其土地利用的动态变化情况,发现耕地、居民点及工矿用地、交通用地、水利设施都有不同程度的增加,园地与牧草地的面积有所减少。接着运用博州社会经济发展状况有关数据和主成分分析法对博州地区面积变化的社会驱动力作定量分析,总结出农业结构的调整、经济发展、农业生产效益、政治经济政策这4个因素是引起博州土地利用变化的主要社会驱动力因子,且第一产业仍然处于主导地位。

  15. 1976年以来江苏盐城滨海湿地景观变化及驱动力分析%Landscape changes of Jiangsu Yancheng coastal wetlands and their driving forces since 1976

    Institute of Scientific and Technical Information of China (English)

    左平; 李云; 赵书河; 周鑫; 滕厚锋; 陈浩

    2012-01-01

    Temporal and spatial variations of landscape changes and their driving forces are analyzed in Yancheng coastal wetlands based on topography data in 1976 and remote sensing data in 1987, 1992, 1997, 2002 and 2007. The results show that the area of Yancheng natural coastal wetlands decreased gradually with the massive loss of Aeluropus sinensis, Suaeda glauca communities and great increase of fish pondsand agricultural lands. A landscape index shows Yancheng coastal wetlands are rapidly deteriorating and experiencing landscape fragmentation. Their driving forces are pushed by both human disturbance and physical conditions with policy-oriented activities of all kinds of wetlands development, alien species introduction and coastal erosion/accretion conditions. The existing development model on Yancheng coastal wetlands might be substituted by wise use and scientific management as soon as possible for the aim of biodiversity conservation and ecosystem health.%基于1976年的地形测绘数据和1987,1992,1997,2002,2007年的遥感数据提取土地利用和景观的时空变化,进而分析近40 a来江苏盐城滨海湿地的景观变化和驱动力.研究表明:自1976年以来盐城滨海湿地中的自然湿地总面积呈逐渐减少的趋势;景观的主要变化特征表现为以獐茅、碱蓬群落为代表的自然湿地的大面积减少,和以鱼塘、农业用地为代表的人工湿地的大面积增加.景观指标分析表明盐城滨海湿地景观总体上有破碎化程度加剧的趋势.结果分析认为,这种变化既受到政策导向型的各类滩涂开发等人为干扰活动的影响,也受到滨海湿地自然演化和潮滩蚀淤等自然因素的影响.尽快改变盐城滨海湿地现有的开发利用模式,使各种人类活动对整个生态系统的压力减到最小,以获得经济、社会、生态效益的统一.

  16. [Bilateral eye injuries by external transversal force].

    Science.gov (United States)

    Geidel, K; Schob, S; Unterlauft, J D; Wiedemann, P; Meier, P

    2016-12-14

    A 49-year-old female victim of violent crime with an acute bilateral loss of vision was referred to our hospital. The ophthalmological evaluation showed complete subconjunctival hemorrhage of both eyes, bilateral hemophthalmos and hypotonia of the left eye. These raised the suspicion of an occult scleral rupture. We immediately performed exploratory surgery and found a perforating scleral lesion of the left eye and a penetrating scleral lesion of the right eye. Furthermore, a small, cruciform wound was detected on the left temple. In cooperation with the department of radiology, the extraordinary injury pattern was reconstructed: a horizontal stab wound with perforation of the left eye and penetration of the right eye caused by a screwdriver. Visual rehabilitation necessitated further surgical interventions. Besides the intraoperative approach, immediate primary wound management within 100 h of trauma plays a pivotal role for long-term outcome.

  17. External Otitis (Swimmer's Ear)

    Science.gov (United States)

    ... to Pneumococcal Vaccine Additional Content Medical News External Otitis (Swimmer's Ear) By Bradley W. Kesser, MD, Associate ... the Outer Ear Ear Blockages Ear Tumors External Otitis (Swimmer's Ear) Malignant External Otitis Perichondritis External otitis ...

  18. Water drives peptide conformational transitions

    CERN Document Server

    Nerukh, Dmitry

    2011-01-01

    Transitions between metastable conformations of a dipeptide are investigated using classical molecular dynamics simulation with explicit water molecules. The distribution of the surrounding water at different moments before the transitions and the dynamical correlations of water with the peptide's configurational motions indicate that water is the main driving force of the conformational changes.

  19. Death Drive in Tourism Studies

    NARCIS (Netherlands)

    Buda, Dorina

    2014-01-01

    The psychoanalytical concept of the death drive refers to a constant metapsychological force at the junction between life and death: it is not understood in a biological sense of physical demise of the body, nor in opposition to life. Geographies of tourist performances in places in the proximity of

  20. Death Drive in Tourism Studies

    NARCIS (Netherlands)

    Buda, Dorina

    2014-01-01

    The psychoanalytical concept of the death drive refers to a constant metapsychological force at the junction between life and death: it is not understood in a biological sense of physical demise of the body, nor in opposition to life. Geographies of tourist performances in places in the proximity of

  1. Standardization of Mobile Satellite Service Technology in ITU-R:Driving Force of Integrated Mobile Services%ITU-R卫星移动通信标准--整合移动业务的动力

    Institute of Scientific and Technical Information of China (English)

    金秀英

    2015-01-01

    认为国际电信联盟无线电通信部门(ITU-R)关于卫星移动通信的标准化新进展将在全球移动通信设备和系统无缝连接的实现过程中起到重要作用,卫星和地面的集成/混合的天地一体化系统将充分发挥原系统各自的优势,未来多数的卫星移动业务(MSS)都将基于这种天地一体化系统。指出IMT-Advanced系统的卫星部分和ITU-R标准化无线接口是集成MSS系统的关键技术,将成为激活MSS产业的新的驱动力。%Wel-developed standards wil play an important role in facilitating seamless interworking of equipment and systems global y. Most future MSS services wil use integrated and/or hybrid satel ite-terrestrial networks that leverage both satel ite and terrestrial networks. Satel ite components of IMT-Advanced systems and ITU-R standardized radio interfaces provide key technology in integrated satel ite and terrestrial networks, and this wil be a new driving force behind MSS industries.

  2. [Study on the types and water pollution driving forces of the typical and medium-small-sized cities in the southern China based on the analysis of water environment].

    Science.gov (United States)

    Jiao, Shi-Xing; Wang, La-Chun; Huo, Yu; Chen, Chang-Chun; Teng, Juan

    2009-07-15

    According to the major pollution sources of urban water environment, 10 indexes such as industrial sewage quantity were closen to establish evaluation indexes system about the types and influencing factors of the typical and medium-small-sized cities in the southern China. Case studies of 16 typical and medium-small-sized cities were taken in Jiangsu, Zhejiang, Hubei and Anhui provinces. Combined with SPSS 11.0 cluster analysis results, city types were divided in reference to the values of water resources comprehensive pollution indexes and economical development indexes. The driving forces about city water environment pollution were studied by principal component analysis method. The result indicates that the 16 cities belong to two categories and four sub-categories, which are rich economy as well as light pollution of water environment and poor economy as well as heavy pollution of water environment. The influencing factors of water environment pollution are in sequence of industrial water pollution, agricultural no-point source pollution and urban domestic water pollution. The main factors of water environment pollution influenced I category cities, II as well as IV category cities and III category cities are industrial water pollution, urban domestic pollution and agricultural no-point source pollution respectively.

  3. Research on Driving Forces of the Education of Martial Arts Morality in Promoting the Development of Teenagers%武德教育对促进青少年健康成长的内驱力研究

    Institute of Scientific and Technical Information of China (English)

    冯庆雨

    2015-01-01

    本文以武德教育和青少年德育为研究对象。结合青少年发育过程中的生理、心理特征,以武德教育为突破口进行研究。分析了现阶段我国青少年思想道德教育中存在的问题;论述了武德教育的时代特性;探讨了武德教育促进青少年健康成长的有机融合研究;提出了武德教育驱动青少年德育建设的有效途径。%This paper takes the education of martial arts morality and teenagers'morality as its research object. The research is carried out by taking its breakthrough from the education of martial arts morality while connecting biological and psychological characteristics of teenagers.It analyzes problems existing in morality education among Chinese teenagers at present and discusses features of education of martial arts morality in modern times.By exploring the organic integration of education of martial arts into the development of teenagers,it proposes effective ways of enhancing driving forces of education of martial arts morality in promoting teenagers'morality.

  4. A comparison of the Wheeler-Jonas model and the linear driving force at constant-pattern model for the prediction of the service time of activated carbon cartridges.

    Science.gov (United States)

    Grévillot, Georges; Marsteau, Stéphanie; Vallières, Cécile

    2011-05-01

    The linear driving force (LDF) model is applied to predict the service life of activated carbon cartridges. It is compared with the currently used Wheeler-Jonas equation, which results from a model of chemical reaction kinetics. The LDF model is based on a mass transfer model of adsorbate into the particle. The two models are studied in constant-pattern conditions. The properties of the two models are first clarified and then compared. It is shown that the Wheeler-Jonas equation leads to symmetrical breakthrough curves, whereas the constant-pattern LDF equation results in asymmetrical curves. Thus, the curvature of the isotherm has no influence on the shape of the Wheeler-Jonas curve. For the LDF breakthrough curve, it is shown that the asymmetry increases with the curvature of the isotherm. Wheeler-Jonas can be used with a Dubinin-Raduskevitch isotherm, whereas the LDF model analytical solution is valid for a Langmuir isotherm only. The LDF model can be used with the DR isotherm, but a numerical solution is required. At very low concentrations where the isotherm is linear, the constant pattern no longer exists and both models fail. The Dubinin-Raduskevitch isotherm must be fitted with a Langmuir isotherm to use the analytical solution of the LDF model.

  5. [Using the 'Driving Force - Pressure - State - Exposure - Effects - Action' (DPSEEA) model of the World Health Organization (WHO) for the analysis of risks related to the use of pesticides in agricultural activities in the state of Rio de Janeiro].

    Science.gov (United States)

    Araújo-Pinto, Mariana de; Peres, Frederico; Moreira, Josino Costa

    2012-06-01

    This paper seeks to apply the DPSEEA model (WHO) to identify major health risks to rural workers and the environment associated with the intensive use of pesticides in the State of Rio de Janeiro, based on an analysis of official public documents and a review of the (national and international) literature. It emphasizes the two main representative branches of agriculture in the state: family farming in the mountain region and the monoculture of sugarcane in the flatlands. Results show that the bulk of the determinants identified in the DPSEEA Matrix are related to deficiencies in actions for monitoring and surveillance of pesticide use, as well as a lack of technical assistance provided by the Public Sector in Rio de Janeiro State. Most of the actions developed in the state address the effects of pesticide exposure and, to a lesser extent, exposure to these chemicals, failing to focus on the higher levels of the matrix (such as driving forces and pressure). These are considered, by several authors, as the most appropriate when tackling the complex and systemic issues, such as the scope of this paper. By means of this study, an attempt was made to enable the application of the DPSEEA Model to assist in environmental and occupational health surveillance initiatives.

  6. Land Use and Land Cover Change in Taohe River Basin and Its Driving Forces%洮河流域土地利用/土地覆被变化及其驱动机制研究

    Institute of Scientific and Technical Information of China (English)

    李常斌; 杨林山; 杨文瑾; 王帅兵

    2014-01-01

    The purpose of this article is to detect the land use and land cover change (LULCC) in Taohe River Basin (TRB) from 1980s to the 2000s and explore its main driving forces. We first build a database of the LULCC by collecting and reorganizing the land use and land cover maps and images, along with data from hy-drometeorologic and socio-economic surveys. The methods that we adopt for estimating the LULCC include the comprehensive utilization index, the transition matrix, and the dynamic index. Correlation analysis and principal components analysis (PCA) are then used for identifying the socioeconomic driving factors of the LULCC before the driving mechanisms are determined through fitting the Multiple Linear Regression Expres-sions (MLREs) to every land use type. It is found that forestland and grassland decreased while cultivated land increased over the past 30 years, despite the obvious heterogeneities in time and space. Temporally, cultivated land and forestland experienced a decline while grassland gained during 1980 s-1990 s;thereafter, cultivated land increased at the expense of forestland and grassland. Spatially, forestland and grassland in the upper and middle reaches of the TRB reduced but cultivated land grew;in the lower reaches, opposite trends took place. Overall, change in cultivated land was the most significant of all land-use types, and both deforestation and af-forestation went on simultaneously. Correlation analysis and PCA show that the LULCC in the TRB were driv-en mostly by the regional economic development, and that the main types of land use-cultivated land, forest-land, and grassland-were also affected by agricultural growth, featuring farming population and area expan-sion. The small categories of land uses-built-up land and water body were influenced by a combined set of"re-gional economy + farming factors + urbanization and climate" driving mechanism. Accordingly, the MLREs were fitted with satisfactory accuracies for both calibration and

  7. 基子集成商视角韵复桑产品系统创新驱动力研究%Research on the Innovation Driving Forces of Complex Products and Systems based on the Perspective of Integrators

    Institute of Scientific and Technical Information of China (English)

    苏敬勤; 刘静

    2012-01-01

    本文采用单案例研究方法,从系统集成商的视角对DJ公司进行了探索性案例研究,运用内容分析法归纳提炼出13个影响DJ公司产品创新的观测变量,形成实证研究量表,并通过问卷调查收集了118个样本数据,运用探索性因子分析的方法对影响因素进行了提取,得出影响复杂产品系统创新的三个主成分因子,即市场控制力、核心技术控制力和动态能力,构成复杂产品系统创新的驱动力主成分。%Complex Products and Systems(COPS) industries play important roles in the economic prosperity of China. CoPS show peculiar features in terms of product characteristics and innovation process. They are custom ized, costly, and technologyintensive products, systems, services, and infrastructure manufactured in single or small batches. During the CoPS innovation process, a system integrator's capabilities directly affect the quality and efficiency of CoPS projects. However, system integrators will not be productive unless they can identify the key fac tors which affect the process of CoPS projects. Because of those different features compared with ordinary masspro duced products theories about product innovation can not available to explain what key factors affect the innovation efficiency of COPS. Therefore, this study highlights the different dimensions of key factors and effects on product in novation in complex product systems innovation and aims to explore drivinz forces (kev factors) of CoPS innovation. In this paper, we used two methods to explore main elements of driving forces (key iactors)of CoPS innova tion. Firstly, the single exploratory case study method is adopted. DL was chose as our case, since the foundation of the People's Republic of China, the Company has successively experienced six large scale technology transforma tions and step by step turned into a modern enterprise being able to design and manufacture highlevel diesel

  8. Collaboration: The Driving Force for Success

    Science.gov (United States)

    Rourke, James; Boone, Elizabeth

    2008-01-01

    Nestled in the mountains and surrounded by Christmas tree farms, Ashe County Middle School is a small, rural school in the far northwest corner of North Carolina. Recognized nationally for its fine academic and co-curricular programs, the school prepares students for high school and real-life situations by teaching important concepts, essential…

  9. Three Driving Forces of Labor Market

    Institute of Scientific and Technical Information of China (English)

    Gao Zhanqiang

    2009-01-01

    @@ The sub prime in Wall Street of USA finally turned into global economic crisis. China, as the second largest export country in the world, caught in the biting cold economic storm. As the declining export directly plays on the weakness of Chinese economy, shrinking domestic demand and weak export market worsens the employment situation in China.

  10. Pattern-formation under acoustic driving forces

    Science.gov (United States)

    Valverde, Jose Manuel

    2015-07-01

    Chemical and metallurgical processes enhanced by high intensity acoustic waves, thermoacoustic engines and refrigerators, fuel rods in nuclear reactors, heat exchanger tubes, offshore and vibrating structures, solar thermal collectors, acoustic levitators, microfluidic devices, cycling, musical acoustics, blood flow through veins/arteries, hearing in the mammalian ear, carbon nanotube loudspeakers, etc. The evolution of a myriad of processes involving the oscillation of viscous fluids in the presence of solid boundaries is up to a certain extent influenced by acoustic streaming. In addition to the sound field, viscous energy dissipation at the fluid-solid boundary causes a time-independent fluid circulation, which can lead to a significant enhancement of heat, mass and momentum transfer at large oscillation amplitudes. A particularly relevant phenomenon that can be notably affected by acoustic streaming is the promotion of sound waves by temperature gradients or viceversa (thermoacoustics), which is at the basis of potentially efficient and environmental friendly engines and refrigerators that have attracted a renewed interest in the last years. In the present manuscript, historical developments and the underlying basic physics behind acoustic streaming and thermoacoustics are reviewed from an unifying perspective.

  11. The driving force role of ruthenacyclobutanes

    KAUST Repository

    Vummaleti, Sai V. C.

    2015-02-07

    DFT calculations have been used to determine the thermodynamic and kinetic preference for ruthenacyclobutanes resulting from the experimentally proposed interconversion pathways (olefin and alkylidene rotations) through the investigation of cross-metathesis reaction mechanism for neutral Grubbs catalyst, RuCl2(=CHEt)NHC (A), with ethylene and 1-butene as the substrates. Our results show that although the proposed interconversions are feasible due to the predicted low energy barriers (2-6 kcal/mol), the formation of ruthenacyclobutane is kinetically favored over the competitive reactions involving alkylidene rotations. In comparison with catalyst A, the reaction energy profile for cationic Piers catalyst [RuCl2(=CHPCy3)NHC+] (B) is more endothermic in nature with both ethylene and 1-butene substrates.

  12. SINEs as driving forces in genome evolution.

    Science.gov (United States)

    Schmitz, J

    2012-01-01

    SINEs are short interspersed elements derived from cellular RNAs that repetitively retropose via RNA intermediates and integrate more or less randomly back into the genome. SINEs propagate almost entirely vertically within their host cells and, once established in the germline, are passed on from generation to generation. As non-autonomous elements, their reverse transcription (from RNA to cDNA) and genomic integration depends on the activity of the enzymatic machinery of autonomous retrotransposons, such as long interspersed elements (LINEs). SINEs are widely distributed in eukaryotes, but are especially effectively propagated in mammalian species. For example, more than a million Alu-SINE copies populate the human genome (approximately 13% of genomic space), and few master copies of them are still active. In the organisms where they occur, SINEs are a challenge to genomic integrity, but in the long term also can serve as beneficial building blocks for evolution, contributing to phenotypic heterogeneity and modifying gene regulatory networks. They substantially expand the genomic space and introduce structural variation to the genome. SINEs have the potential to mutate genes, to alter gene expression, and to generate new parts of genes. A balanced distribution and controlled activity of such properties is crucial to maintaining the organism's dynamic and thriving evolution.

  13. Quantum metrology. Optically measuring force near the standard quantum limit.

    Science.gov (United States)

    Schreppler, Sydney; Spethmann, Nicolas; Brahms, Nathan; Botter, Thierry; Barrios, Maryrose; Stamper-Kurn, Dan M

    2014-06-27

    The Heisenberg uncertainty principle sets a lower bound on the noise in a force measurement based on continuously detecting a mechanical oscillator's position. This bound, the standard quantum limit, can be reached when the oscillator subjected to the force is unperturbed by its environment and when measurement imprecision from photon shot noise is balanced against disturbance from measurement back-action. We applied an external force to the center-of-mass mot