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Sample records for adaptive step size

  1. A chaos detectable and time step-size adaptive numerical scheme for nonlinear dynamical systems

    NASA Astrophysics Data System (ADS)

    Chen, Yung-Wei; Liu, Chein-Shan; Chang, Jiang-Ren

    2007-02-01

    The first step in investigation the dynamics of a continuous time system described by ordinary differential equations is to integrate them to obtain trajectories. In this paper, we convert the group-preserving scheme (GPS) developed by Liu [International Journal of Non-Linear Mechanics 36 (2001) 1047-1068] to a time step-size adaptive scheme, x=x+hf(x,t), where x∈R is the system variables we are concerned with, and f(x,t)∈R is a time-varying vector field. The scheme has the form similar to the Euler scheme, x=x+Δtf(x,t), but our step-size h is adaptive automatically. Very interestingly, the ratio h/Δt, which we call the adaptive factor, can forecast the appearance of chaos if the considered dynamical system becomes chaotical. The numerical examples of the Duffing equation, the Lorenz equation and the Rossler equation, which may exhibit chaotic behaviors under certain parameters values, are used to demonstrate these phenomena. Two other non-chaotic examples are included to compare the performance of the GPS and the adaptive one.

  2. Search Control Algorithm Based on Random Step Size Hill-Climbing Method for Adaptive PMD Compensation

    NASA Astrophysics Data System (ADS)

    Tanizawa, Ken; Hirose, Akira

    Adaptive polarization mode dispersion (PMD) compensation is required for the speed-up and advancement of the present optical communications. The combination of a tunable PMD compensator and its adaptive control method achieves adaptive PMD compensation. In this paper, we report an effective search control algorithm for the feedback control of the PMD compensator. The algorithm is based on the hill-climbing method. However, the step size changes randomly to prevent the convergence from being trapped at a local maximum or a flat, unlike the conventional hill-climbing method. The randomness depends on the Gaussian probability density functions. We conducted transmission simulations at 160Gb/s and the results show that the proposed method provides more optimal compensator control than the conventional hill-climbing method.

  3. Transform Domain Robust Variable Step Size Griffiths' Adaptive Algorithm for Noise Cancellation in ECG

    NASA Astrophysics Data System (ADS)

    Hegde, Veena; Deekshit, Ravishankar; Satyanarayana, P. S.

    2011-12-01

    The electrocardiogram (ECG) is widely used for diagnosis of heart diseases. Good quality of ECG is utilized by physicians for interpretation and identification of physiological and pathological phenomena. However, in real situations, ECG recordings are often corrupted by artifacts or noise. Noise severely limits the utility of the recorded ECG and thus needs to be removed, for better clinical evaluation. In the present paper a new noise cancellation technique is proposed for removal of random noise like muscle artifact from ECG signal. A transform domain robust variable step size Griffiths' LMS algorithm (TVGLMS) is proposed for noise cancellation. For the TVGLMS, the robust variable step size has been achieved by using the Griffiths' gradient which uses cross-correlation between the desired signal contaminated with observation or random noise and the input. The algorithm is discrete cosine transform (DCT) based and uses symmetric property of the signal to represent the signal in frequency domain with lesser number of frequency coefficients when compared to that of discrete Fourier transform (DFT). The algorithm is implemented for adaptive line enhancer (ALE) filter which extracts the ECG signal in a noisy environment using LMS filter adaptation. The proposed algorithm is found to have better convergence error/misadjustment when compared to that of ordinary transform domain LMS (TLMS) algorithm, both in the presence of white/colored observation noise. The reduction in convergence error achieved by the new algorithm with desired signal decomposition is found to be lower than that obtained without decomposition. The experimental results indicate that the proposed method is better than traditional adaptive filter using LMS algorithm in the aspects of retaining geometrical characteristics of ECG signal.

  4. The Dynamics of Cumulative Step Size Adaptation on the Ellipsoid Model.

    PubMed

    Beyer, Hans-Georg; Hellwig, Michael

    2016-01-01

    The behavior of the [Formula: see text]-Evolution Strategy (ES) with cumulative step size adaptation (CSA) on the ellipsoid model is investigated using dynamic systems analysis. At first a nonlinear system of difference equations is derived that describes the mean value evolution of the ES. This system is successively simplified to finally allow for deriving closed-form solutions of the steady state behavior in the asymptotic limit case of large search space dimensions. It is shown that the system exhibits linear convergence order. The steady state mutation strength is calculated, and it is shown that compared to standard settings in [Formula: see text] self-adaptive ESs, the CSA control rule allows for an approximately [Formula: see text]-fold larger mutation strength. This explains the superior performance of the CSA in non-noisy environments. The results are used to derive a formula for the expected running time. Conclusions regarding the choice of the cumulation parameter c and the damping constant D are drawn.

  5. A family of variable step-size affine projection adaptive filter algorithms using statistics of channel impulse response

    NASA Astrophysics Data System (ADS)

    Shams Esfand Abadi, Mohammad; AbbasZadeh Arani, Seyed Ali Asghar

    2011-12-01

    This paper extends the recently introduced variable step-size (VSS) approach to the family of adaptive filter algorithms. This method uses prior knowledge of the channel impulse response statistic. Accordingly, optimal step-size vector is obtained by minimizing the mean-square deviation (MSD). The presented algorithms are the VSS affine projection algorithm (VSS-APA), the VSS selective partial update NLMS (VSS-SPU-NLMS), the VSS-SPU-APA, and the VSS selective regressor APA (VSS-SR-APA). In VSS-SPU adaptive algorithms the filter coefficients are partially updated which reduce the computational complexity. In VSS-SR-APA, the optimal selection of input regressors is performed during the adaptation. The presented algorithms have good convergence speed, low steady state mean square error (MSE), and low computational complexity features. We demonstrate the good performance of the proposed algorithms through several simulations in system identification scenario.

  6. Adaptive step-size algorithm for Fourier beam-propagation method with absorbing boundary layer of auto-determined width

    SciTech Connect

    Learn, R.; Feigenbaum, E.

    2016-05-27

    Two algorithms that enhance the utility of the absorbing boundary layer are presented, mainly in the framework of the Fourier beam-propagation method. One is an automated boundary layer width selector that chooses a near-optimal boundary size based on the initial beam shape. Furthermore, the second algorithm adjusts the propagation step sizes based on the beam shape at the beginning of each step in order to reduce aliasing artifacts.

  7. Numerosity perception after size adaptation

    PubMed Central

    Zimmermann, Eckart; Fink, Gereon R.

    2016-01-01

    While some researchers propose the existence of a special numerosity sense, others challenge this view and argue that numerosity is derived from low-level features as density information. Here, we used size adaptation to manipulate the apparent area size of an object set without changing its physical density. After size adaptation, two probe patches were shown, each of which contained a specific numerosity of dots. Subjects were required to report, which probe patch contained more dots. Numerosity perception was compared between conditions where probe patches were adapted to appear smaller or larger. Size adaptation affected numerosity perception in a logarithmic fashion, increasing with the numerosity in the probe patch. No changes in density perception were found after size adaptation. Data suggest that size and density information play only a minor role in the estimation of low numerosities. In stark contrast, high numerosities strongly depend on size and density information. The data reinforce recent claims of separate mechanism for the perception of low and high numerosities. PMID:27650296

  8. An adaptive out-of-step relay

    SciTech Connect

    Centeno, V.; Phadke, A.G.; Edris, A.; Benton, J.; Gaudi, M.; Michel, G.

    1997-01-01

    The paper describes the development of an adaptive out-of-step relay, from the formulation of its concept to its field implementation at the Florida-Georgia interface. Adaptive relaying seeks to make adjustments to the relay characteristics as system conditions change, thereby making the relay more attuned to the prevailing power system conditions. The work described here began as a theoretical examination of the out-of-step relaying application, its possible shortcomings, and the opportunities to make adaptive improvements. It is shown that for a system that behaves primarily as a two-machine power system, the out-of-step relay could be made more secure by applying the principle of equal area criterion. The paper describes the theory of such a relay, its hardware configuration, and the system as it is installed in the field. The newly developed technology of synchronized phasor measurements plays an important role in the realization of this relay. The paper includes a summary of the field experience gathered over a period of one year.

  9. Stepwise two-stage sample size adaptation.

    PubMed

    Wan, Hong; Ellenberg, Susan S; Anderson, Keaven M

    2015-01-15

    Several adaptive design methods have been proposed to reestimate sample size using the observed treatment effect after an initial stage of a clinical trial while preserving the overall type I error at the time of the final analysis. One unfortunate property of the algorithms used in some methods is that they can be inverted to reveal the exact treatment effect at the interim analysis. We propose using a step function with an inverted U-shape of observed treatment difference for sample size reestimation to lessen the information on treatment effect revealed. This will be referred to as stepwise two-stage sample size adaptation. This method applies calculation methods used for group sequential designs. We minimize expected sample size among a class of these designs and compare efficiency with the fully optimized two-stage design, optimal two-stage group sequential design, and designs based on promising conditional power. The trade-off between efficiency versus the improved blinding of the interim treatment effect will be discussed.

  10. Stepping strategies for regulating gait adaptability and stability.

    PubMed

    Hak, Laura; Houdijk, Han; Steenbrink, Frans; Mert, Agali; van der Wurff, Peter; Beek, Peter J; van Dieën, Jaap H

    2013-03-15

    Besides a stable gait pattern, gait in daily life requires the capability to adapt this pattern in response to environmental conditions. The purpose of this study was to elucidate the anticipatory strategies used by able-bodied people to attain an adaptive gait pattern, and how these strategies interact with strategies used to maintain gait stability. Ten healthy subjects walked in a Computer Assisted Rehabilitation ENvironment (CAREN). To provoke an adaptive gait pattern, subjects had to hit virtual targets, with markers guided by their knees, while walking on a self-paced treadmill. The effects of walking with and without this task on walking speed, step length, step frequency, step width and the margins of stability (MoS) were assessed. Furthermore, these trials were performed with and without additional continuous ML platform translations. When an adaptive gait pattern was required, subjects decreased step length (p<0.01), tended to increase step width (p=0.074), and decreased walking speed while maintaining similar step frequency compared to unconstrained walking. These adaptations resulted in the preservation of equal MoS between trials, despite the disturbing influence of the gait adaptability task. When the gait adaptability task was combined with the balance perturbation subjects further decreased step length, as evidenced by a significant interaction between both manipulations (p=0.012). In conclusion, able-bodied people reduce step length and increase step width during walking conditions requiring a high level of both stability and adaptability. Although an increase in step frequency has previously been found to enhance stability, a faster movement, which would coincide with a higher step frequency, hampers accuracy and may consequently limit gait adaptability.

  11. Secondary tasks impair adaptation to step and gradual visual displacements

    PubMed Central

    Galea, J.M.; Sami, S.; Albert, N.B.; Miall, R.C.

    2016-01-01

    Performing two competing tasks can result in dividing cognitive resources between the tasks and impaired motor adaptation. In previous work we have reported impaired learning when participants had to switch from one visual displacement adaptation task to another. Here we examined whether or not a secondary task had a similar effect on adaptation to a visual displacement . The resource dividing task involved simultaneously adapting to a step visual displacement whilst vocally shadowing an auditory stimulus . The switching task required participants to adapt to opposing visual displacements in an alternating manner with the left and right hands. We found that both manipulations had a detrimental effect on adaptation rate. We then integrated these tasks and found the combination caused a greater decrease in adaptation rate than either manipulation in isolation. Experiment 2 showed that adaptation to a gradually imposed visual displacement was influenced in a similar manner to step adaptation. Therefore although gradual adaptation involves minimal awareness it still can be disrupted by a cognitively demanding secondary task. We propose that awareness and cognitive resource can be regarded as qualitatively different but that awareness may be a marker of the amount of resource required. For example, large errors are both noticed and require substantial cognitive resource to connect. However a lack of awareness does not mean an adaptation task will be resistant to interference from a resource consuming secondary task. PMID:20101396

  12. Adaptive size modification by dominant female meerkats.

    PubMed

    Russell, Andrew F; Carlson, Anne A; McIlrath, Grant M; Jordan, Neil R; Clutton-Brock, Tim

    2004-07-01

    In species of cooperative insects that live in large groups, selection for increased fecundity has led to the evolution of an increased body size among female reproductives, but whether this is also true of cooperative vertebrates is unknown. Among vertebrates, morphological modification of female breeders has only been documented in a single species; in naked mole rats (Heterocephalus glaber), acquisition of alpha status is associated with a significant increase in body size through an elongation of the lumbar vertebrae. Here we provide evidence of morphological modification among breeding females of a cooperative carnivore, the meerkat (Suricata suricatta), and demonstrate that this modification is likely to be adaptive. The same female meerkats were significantly larger when they were dominant than when they were subordinate. This increased body size was not explained by differences in age, foraging efficiency, or investment in offspring care, but may have arisen, in part, through increased levels of hormone that govern bone growth. Increases in body size are likely to result in fitness benefits, for large females delivered larger litters and had heavier offspring, both of which are known to correlate positively with measures of breeding success in meerkats. Our results suggest that the acquisition of alpha status in female meerkats is associated with an adaptive increase in body size and hence that morphological modification of female vertebrates may be more widespread than has been previously supposed.

  13. Size distributions of quantum islands on stepped substrates.

    PubMed

    Liang, S; Zhu, H L; Wang, W

    2009-10-21

    The size distributions of self-assembled quantum islands on stepped substrates are studied using kinetic Monte Carlo simulations. It is found that the energy barrier E(SW) between the step and the terrace region is the key factor in affecting the size distribution of islands. With small E(SW) (< or = 0.1 eV), lines of uniform islands can be obtained at relative low surface coverage. As the surface coverage is increased, wirelike islands can be obtained. Scaling behavior is obeyed for the size distributions of the wirelike islands. When the size distributions are separated into their width and length components, however, scaling is only observed in the length distribution of the wirelike islands. With larger E(SW), the size distribution of islands shows a clear bimodal size distribution and anomalous growth temperature dependent island size evolutions are observed. The simulation results reproduce qualitatively the phenomena observed in the cases of InAs islands grown on stepped GaAs substrates.

  14. Adaptive time steps in trajectory surface hopping simulations

    NASA Astrophysics Data System (ADS)

    Spörkel, Lasse; Thiel, Walter

    2016-05-01

    Trajectory surface hopping (TSH) simulations are often performed in combination with active-space multi-reference configuration interaction (MRCI) treatments. Technical problems may arise in such simulations if active and inactive orbitals strongly mix and switch in some particular regions. We propose to use adaptive time steps when such regions are encountered in TSH simulations. For this purpose, we present a computational protocol that is easy to implement and increases the computational effort only in the critical regions. We test this procedure through TSH simulations of a GFP chromophore model (OHBI) and a light-driven rotary molecular motor (F-NAIBP) on semiempirical MRCI potential energy surfaces, by comparing the results from simulations with adaptive time steps to analogous ones with constant time steps. For both test molecules, the number of successful trajectories without technical failures rises significantly, from 53% to 95% for OHBI and from 25% to 96% for F-NAIBP. The computed excited-state lifetime remains essentially the same for OHBI and increases somewhat for F-NAIBP, and there is almost no change in the computed quantum efficiency for internal rotation in F-NAIBP. We recommend the general use of adaptive time steps in TSH simulations with active-space CI methods because this will help to avoid technical problems, increase the overall efficiency and robustness of the simulations, and allow for a more complete sampling.

  15. Selecting step sizes in sensitivity analysis by finite differences

    NASA Technical Reports Server (NTRS)

    Iott, J.; Haftka, R. T.; Adelman, H. M.

    1985-01-01

    This paper deals with methods for obtaining near-optimum step sizes for finite difference approximations to first derivatives with particular application to sensitivity analysis. A technique denoted the finite difference (FD) algorithm, previously described in the literature and applicable to one derivative at a time, is extended to the calculation of several simultaneously. Both the original and extended FD algorithms are applied to sensitivity analysis for a data-fitting problem in which derivatives of the coefficients of an interpolation polynomial are calculated with respect to uncertainties in the data. The methods are also applied to sensitivity analysis of the structural response of a finite-element-modeled swept wing. In a previous study, this sensitivity analysis of the swept wing required a time-consuming trial-and-error effort to obtain a suitable step size, but it proved to be a routine application for the extended FD algorithm herein.

  16. Automatic multirate methods for ordinary differential equations. [Adaptive time steps

    SciTech Connect

    Gear, C.W.

    1980-01-01

    A study is made of the application of integration methods in which different step sizes are used for different members of a system of equations. Such methods can result in savings if the cost of derivative evaluation is high or if a system is sparse; however, the estimation and control of errors is very difficult and can lead to high overheads. Three approaches are discussed, and it is shown that the least intuitive is the most promising. 2 figures.

  17. A new adaptive time step method for unsteady flow simulations in a human lung.

    PubMed

    Fenández-Tena, Ana; Marcos, Alfonso C; Martínez, Cristina; Keith Walters, D

    2017-04-07

    The innovation presented is a method for adaptive time-stepping that allows clustering of time steps in portions of the cycle for which flow variables are rapidly changing, based on the concept of using a uniform step in a relevant dependent variable rather than a uniform step in the independent variable time. A user-defined function was developed to adapt the magnitude of the time step (adaptive time step) to a defined rate of change in inlet velocity. Quantitative comparison indicates that the new adaptive time stepping method significantly improves accuracy for simulations using an equivalent number of time steps per cycle.

  18. In vivo myosin step-size from zebrafish skeletal muscle

    PubMed Central

    Ajtai, Katalin; Sun, Xiaojing; Takubo, Naoko; Wang, Yihua

    2016-01-01

    Muscle myosins transduce ATP free energy into actin displacement to power contraction. In vivo, myosin side chains are modified post-translationally under native conditions, potentially impacting function. Single myosin detection provides the ‘bottom-up’ myosin characterization probing basic mechanisms without ambiguities inherent to ensemble observation. Macroscopic muscle physiological experimentation provides the definitive ‘top-down’ phenotype characterizations that are the concerns in translational medicine. In vivo single myosin detection in muscle from zebrafish embryo models for human muscle fulfils ambitions for both bottom-up and top-down experimentation. A photoactivatable green fluorescent protein (GFP)-tagged myosin light chain expressed in transgenic zebrafish skeletal muscle specifically modifies the myosin lever-arm. Strychnine induces the simultaneous contraction of the bilateral tail muscles in a live embryo, causing them to be isometric while active. Highly inclined thin illumination excites the GFP tag of single lever-arms and its super-resolution orientation is measured from an active isometric muscle over a time sequence covering many transduction cycles. Consecutive frame lever-arm angular displacement converts to step-size by its product with the estimated lever-arm length. About 17% of the active myosin steps that fall between 2 and 7 nm are implicated as powerstrokes because they are beyond displacements detected from either relaxed or ATP-depleted (rigor) muscle. PMID:27249818

  19. Variable step size and order strategy for delay differential equations in PIE(CIE)s mode

    NASA Astrophysics Data System (ADS)

    Aziz, Nurul Huda Abdul; Majid, Zanariah Abdul

    2014-12-01

    This article deals with the strategy of variable step size and variable order implementation that has been formulated for solving first order of delay differential equations. This strategy is adapted in PIE(CIE)s mode which is generally based on predictor-corrector scheme in multistep block method of order 4 to 9 with s is for convergence test. The purpose here is to enhance the efficiency of the developed predictor-corrector algorithm in the capability to vary automatically not only for the step size, but the order of the method employed as well. All order and coefficients are stored in the code in order to avoid an expensive computational work. The delay argument would be evaluated using Newton divided-difference interpolation at which the points involved would be similar to the current order of the method. Illustrative examples are included to demonstrate the validity and applicability of the presented strategy and comparison is made with the existing results.

  20. Concurrent directional adaptation of reactive saccades and hand movements to target displacements of different size.

    PubMed

    Borisova, Steliana; Bock, Otmar; Grigorova, Valentina

    2014-01-01

    When eye and hand movements are concurrently aimed at double-step targets that call for equal and opposite changes of response direction (-10° for the eyes, +10° for the hand), adaptive recalibration of both motor systems is strongly attenuated; instead, hand but not eye movements are changed by corrective strategies (V. Grigorova et al., 2013a). The authors introduce a complementary paradigm, where double-step targets call for a -10° change of eye and a -30° change for hand movements. If compared to control subjects adapting only the eyes or only the hand, adaptive improvements were comparable for the eyes but were twice as large for the hand; in contrast, eye and hand aftereffects were comparable to those in control subjects. The authors concluded that concurrent exposure of eyes and hand to steps of the same direction but different size facilitated hand strategies, but didn't affect recalibration. This finding together with previous one (V. Grigorova et al., 2013a), suggests that concurrent adaptation of eyes and hand reveals different mechanisms of recalibration for step sign and step size, which are shared by reactive saccades and hand movements. However, hand mostly benefits from strategies provoked by the difference in target step sign and size.

  1. Awareness of sensorimotor adaptation to visual rotations of different size.

    PubMed

    Werner, Susen; van Aken, Bernice C; Hulst, Thomas; Frens, Maarten A; van der Geest, Jos N; Strüder, Heiko K; Donchin, Opher

    2015-01-01

    Previous studies on sensorimotor adaptation revealed no awareness of the nature of the perturbation after adaptation to an abrupt 30° rotation of visual feedback or after adaptation to gradually introduced perturbations. Whether the degree of awareness depends on the magnitude of the perturbation, though, has as yet not been tested. Instead of using questionnaires, as was often done in previous work, the present study used a process dissociation procedure to measure awareness and unawareness. A naïve, implicit group and a group of subjects using explicit strategies adapted to 20°, 40° and 60° cursor rotations in different adaptation blocks that were each followed by determination of awareness and unawareness indices. The awareness index differed between groups and increased from 20° to 60° adaptation. In contrast, there was no group difference for the unawareness index, but it also depended on the size of the rotation. Early adaptation varied between groups and correlated with awareness: The more awareness a participant had developed the more the person adapted in the beginning of the adaptation block. In addition, there was a significant group difference for savings but it did not correlate with awareness. Our findings suggest that awareness depends on perturbation size and that aware and strategic processes are differentially involved during adaptation and savings. Moreover, the use of the process dissociation procedure opens the opportunity to determine awareness and unawareness indices in future sensorimotor adaptation research.

  2. Multi time-step wavefront reconstruction for tomographic adaptive-optics systems.

    PubMed

    Ono, Yoshito H; Akiyama, Masayuki; Oya, Shin; Lardiére, Olivier; Andersen, David R; Correia, Carlos; Jackson, Kate; Bradley, Colin

    2016-04-01

    In tomographic adaptive-optics (AO) systems, errors due to tomographic wavefront reconstruction limit the performance and angular size of the scientific field of view (FoV), where AO correction is effective. We propose a multi time-step tomographic wavefront reconstruction method to reduce the tomographic error by using measurements from both the current and previous time steps simultaneously. We further outline the method to feed the reconstructor with both wind speed and direction of each turbulence layer. An end-to-end numerical simulation, assuming a multi-object AO (MOAO) system on a 30 m aperture telescope, shows that the multi time-step reconstruction increases the Strehl ratio (SR) over a scientific FoV of 10 arc min in diameter by a factor of 1.5-1.8 when compared to the classical tomographic reconstructor, depending on the guide star asterism and with perfect knowledge of wind speeds and directions. We also evaluate the multi time-step reconstruction method and the wind estimation method on the RAVEN demonstrator under laboratory setting conditions. The wind speeds and directions at multiple atmospheric layers are measured successfully in the laboratory experiment by our wind estimation method with errors below 2  ms-1. With these wind estimates, the multi time-step reconstructor increases the SR value by a factor of 1.2-1.5, which is consistent with a prediction from the end-to-end numerical simulation.

  3. Opinion: Adaptive Computing and the Internet: One Step forward, Two Steps Back?

    ERIC Educational Resources Information Center

    Lazzaro, Joseph J.

    1994-01-01

    This overview of adaptive technology for computers and networking identifies issues that must be addressed for people with disabilities to participate fully in online activities. Discussion includes adaptive equipment; Internet access; and graphical user interface (GUI) concerns. Contact information for vendors for adaptive technology and…

  4. Effects of Calibration Sample Size and Item Bank Size on Ability Estimation in Computerized Adaptive Testing

    ERIC Educational Resources Information Center

    Sahin, Alper; Weiss, David J.

    2015-01-01

    This study aimed to investigate the effects of calibration sample size and item bank size on examinee ability estimation in computerized adaptive testing (CAT). For this purpose, a 500-item bank pre-calibrated using the three-parameter logistic model with 10,000 examinees was simulated. Calibration samples of varying sizes (150, 250, 350, 500,…

  5. Environmental adaptation in stomatal size independent of the effects of genome size

    PubMed Central

    Jordan, Gregory J; Carpenter, Raymond J; Koutoulis, Anthony; Price, Aina; Brodribb, Timothy J

    2015-01-01

    Cell sizes are linked across multiple tissues, including stomata, and this variation is closely correlated with genome size. These associations raise the question of whether generic changes in cell size cause suboptimal changes in stomata, requiring subsequent evolution under selection for stomatal size. We tested the relationships among guard cell length, genome size and vegetation type using phylogenetically independent analyses on 67 species of the ecologically and structurally diverse family, Proteaceae. We also compared how genome and stomatal sizes varied at ancient (among genera) and more recent (within genus) levels. The observed 60-fold range in genome size in Proteaceae largely reflected the mean chromosome size. Compared with variation among genera, genome size varied much less within genera (< 6% of total variance) than stomatal size, implying evolution in stomatal size subsequent to changes in genome size. Open vegetation and closed forest had significantly different relationships between stomatal and genome sizes. Ancient changes in genome size clearly influenced stomatal size in Proteaceae, but adaptation to habitat strongly modified the genome–stomatal size relationship. Direct adaptation to the environment in stomatal size argues that new proxies for past concentrations of atmospheric CO2 that incorporate stomatal size are superior to older models based solely on stomatal frequency. PMID:25266914

  6. Adaptive spectral window sizes for feature extraction from optical spectra

    NASA Astrophysics Data System (ADS)

    Kan, Chih-Wen; Lee, Andy Y.; Pham, Nhi; Nieman, Linda T.; Sokolov, Konstantin; Markey, Mia K.

    2008-02-01

    We propose an approach to adaptively adjust the spectral window size used to extract features from optical spectra. Previous studies have employed spectral features extracted by dividing the spectra into several spectral windows of a fixed width. However, the choice of spectral window size was arbitrary. We hypothesize that by adaptively adjusting the spectral window sizes, the trends in the data will be captured more accurately. Our method was tested on a diffuse reflectance spectroscopy dataset obtained in a study of oblique polarization reflectance spectroscopy of oral mucosa lesions. The diagnostic task is to classify lesions into one of four histopathology groups: normal, benign, mild dysplasia, or severe dysplasia (including carcinoma). Nine features were extracted from each of the spectral windows. We computed the area (AUC) under Receiver Operating Characteristic curve to select the most discriminatory wavelength intervals. We performed pairwise classifications using Linear Discriminant Analysis (LDA) with leave-one-out cross validation. The results showed that for discriminating benign lesions from mild or severe dysplasia, the adaptive spectral window size features achieved AUC of 0.84, while a fixed spectral window size of 20 nm had AUC of 0.71, and an AUC of 0.64 is achieved with a large window size containing all wavelengths. The AUCs of all feature combinations were also calculated. These results suggest that the new adaptive spectral window size method effectively extracts features that enable accurate classification of oral mucosa lesions.

  7. Factors influencing the effect size distribution of adaptive substitutions

    PubMed Central

    Oakley, Christopher G.; Gould, Billie A.; Schemske, Douglas W.

    2016-01-01

    The distribution of effect sizes of adaptive substitutions has been central to evolutionary biology since the modern synthesis. Early theory proposed that because large-effect mutations have negative pleiotropic consequences, only small-effect mutations contribute to adaptation. More recent theory suggested instead that large-effect mutations could be favoured when populations are far from their adaptive peak. Here we suggest that the distributions of effect sizes are expected to differ among study systems, reflecting the wide variation in evolutionary forces and ecological conditions experienced in nature. These include selection, mutation, genetic drift, gene flow, and other factors such as the degree of pleiotropy, the distance to the phenotypic optimum, whether the optimum is stable or moving, and whether new mutation or standing genetic variation provides the source of adaptive alleles. Our goal is to review how these factors might affect the distribution of effect sizes and to identify new research directions. Until more theory and empirical work is available, we feel that it is premature to make broad generalizations about the effect size distribution of adaptive substitutions important in nature. PMID:27053750

  8. Projection Operator: A Step Towards Certification of Adaptive Controllers

    NASA Technical Reports Server (NTRS)

    Larchev, Gregory V.; Campbell, Stefan F.; Kaneshige, John T.

    2010-01-01

    One of the major barriers to wider use of adaptive controllers in commercial aviation is the lack of appropriate certification procedures. In order to be certified by the Federal Aviation Administration (FAA), an aircraft controller is expected to meet a set of guidelines on functionality and reliability while not negatively impacting other systems or safety of aircraft operations. Due to their inherent time-variant and non-linear behavior, adaptive controllers cannot be certified via the metrics used for linear conventional controllers, such as gain and phase margin. Projection Operator is a robustness augmentation technique that bounds the output of a non-linear adaptive controller while conforming to the Lyapunov stability rules. It can also be used to limit the control authority of the adaptive component so that the said control authority can be arbitrarily close to that of a linear controller. In this paper we will present the results of applying the Projection Operator to a Model-Reference Adaptive Controller (MRAC), varying the amount of control authority, and comparing controller s performance and stability characteristics with those of a linear controller. We will also show how adjusting Projection Operator parameters can make it easier for the controller to satisfy the certification guidelines by enabling a tradeoff between controller s performance and robustness.

  9. INTERACTING EFFECTS OF VARYING STEP-SIZE AND FEEDBACK IN PROGRAMED INSTRUCTION.

    ERIC Educational Resources Information Center

    GORDON, JOHN M., JR.

    THE FOLLOWING HYPOTHESES WERE TESTED DURING THIS STUDY--(1) PROVIDING KNOWLEDGE OF CORRECT RESPONSE DOES NOT INCREASE THE EFFECTIVENESS OF SMALL STEP-SIZE PROGRAMS FOR STUDENTS AT ALL ACHIEVEMENT LEVELS, (2) PROVIDING KNOWLEDGE OF CORRECT RESPONSE DOES INCREASE THE EFFECTIVENESS OF MODERATE STEP-SIZE PROGRAMS AT ALL ACHIEVEMENT LEVELS, AND (3)…

  10. Performance Comparison of Variable Step Size Techniques of Sato and Godard-Based Blind Equalizer

    NASA Astrophysics Data System (ADS)

    Suthendran, K.; Arivoli, T.

    2015-04-01

    The modern digital high speed wireless communication system demands quick convergence rate and low steady state error. The balancing between the demands can be achieved by opting step size. Thus, it is essential to define new algorithms to equalize channels and mitigate noise in communications. It is renowned that time varying step size blind equalization technique can speed up the convergence rate and minimize the misadjustment. This work presents a variable step size (VSS) approach based on godard blind equalization algorithm to resolve the conflict between the convergence rate and precision of the fixed step-size godard algorithm. The results of this projected approach is compared with the existing variable step size sato algorithm for a pulse amplitude modulated (PAM) input symbol.

  11. Local Discontinuous Galerkin Approximations And Variable Step Size, Variable Order Time Integration For Richards' Equation

    NASA Astrophysics Data System (ADS)

    Li, H.; Farthing, M. W.; Dawson, C. N.; Miller, C. T.

    2004-12-01

    Numerical simulation of Richards' equation continues to be difficult. It is highly nonlinear under common constitutive relations and exhibits sharp fronts in both the pressure head and volume fraction for many problems of interest. For a number of multiphase flow problems, the use of variable order and variable step size temporal discretizations has shown some advantages. However, the spatial discretizations commonly used for variably saturated flow are dominated by nonadaptive, low-order finite difference and finite element methods. Discontinuous Galerkin (DG) finite element methods have received significant attention in a number of fields for hyperbolic PDE's and, more recently, for elliptic and parabolic problems. DG approaches like the local discontinuous Galerkin (LDG) method are appealing for modeling subsurface flow since they can lead to velocity fields that are locally mass-conservative without the need for auxiliary variables or alternative meshes. DG discretizations are also inherently local and so better-suited for unstructured meshes and h-p adaption strategies than traditional methods. While some work has been done recently for multiphase subsurface flow, there are a range of issues related to the performance of DG methods for highly nonlinear parabolic problems like Richards' equation that have not been investigated fully. In this work, we consider the combination of higher order adaptive time integration with an LDG spatial discretization for Richards' equation. We compare this approach to standard low-order methods for a series of test problems and consider a number of issues including the methods' relative accuracy and computational efficiency.

  12. Finite element/finite volume approaches with adaptive time stepping strategies for transient thermal problems

    NASA Technical Reports Server (NTRS)

    Mohan, Ram V.; Tamma, Kumar K.

    1993-01-01

    An adaptive time stepping strategy for transient thermal analysis of engineering systems is described which computes the time step based on the local truncation error with a good global error control and obtains optimal time steps to be used during the analysis. Combined mesh partitionings involving FEM/FVM meshes based on physical situations to obtain numerically improved physical representations are also proposed. Numerical test cases are described and comparative pros and cons are identified for practical situations.

  13. In Vitro and In Vivo Single Myosin Step-Sizes in Striated Muscle a

    PubMed Central

    Burghardt, Thomas P.; Sun, Xiaojing; Wang, Yihua; Ajtai, Katalin

    2016-01-01

    Myosin in muscle transduces ATP free energy into the mechanical work of moving actin. It has a motor domain transducer containing ATP and actin binding sites, and, mechanical elements coupling motor impulse to the myosin filament backbone providing transduction/mechanical-coupling. The mechanical coupler is a lever-arm stabilized by bound essential and regulatory light chains. The lever-arm rotates cyclically to impel bound filamentous actin. Linear actin displacement due to lever-arm rotation is the myosin step-size. A high-throughput quantum dot labeled actin in vitro motility assay (Qdot assay) measures motor step-size in the context of an ensemble of actomyosin interactions. The ensemble context imposes a constant velocity constraint for myosins interacting with one actin filament. In a cardiac myosin producing multiple step-sizes, a “second characterization” is step-frequency that adjusts longer step-size to lower frequency maintaining a linear actin velocity identical to that from a shorter step-size and higher frequency actomyosin cycle. The step-frequency characteristic involves and integrates myosin enzyme kinetics, mechanical strain, and other ensemble affected characteristics. The high-throughput Qdot assay suits a new paradigm calling for wide surveillance of the vast number of disease or aging relevant myosin isoforms that contrasts with the alternative model calling for exhaustive research on a tiny subset myosin forms. The zebrafish embryo assay (Z assay) performs single myosin step-size and step-frequency assaying in vivo combining single myosin mechanical and whole muscle physiological characterizations in one model organism. The Qdot and Z assays cover “bottom-up” and “top-down” assaying of myosin characteristics. PMID:26728749

  14. An adaptive time-stepping strategy for solving the phase field crystal model

    SciTech Connect

    Zhang, Zhengru; Ma, Yuan; Qiao, Zhonghua

    2013-09-15

    In this work, we will propose an adaptive time step method for simulating the dynamics of the phase field crystal (PFC) model. The numerical simulation of the PFC model needs long time to reach steady state, and then large time-stepping method is necessary. Unconditionally energy stable schemes are used to solve the PFC model. The time steps are adaptively determined based on the time derivative of the corresponding energy. It is found that the use of the proposed time step adaptivity cannot only resolve the steady state solution, but also the dynamical development of the solution efficiently and accurately. The numerical experiments demonstrate that the CPU time is significantly saved for long time simulations.

  15. Sensitivity of a thermodynamic sea ice model with leads to time step size

    NASA Technical Reports Server (NTRS)

    Ledley, T. S.

    1985-01-01

    The characteristics of sea ice models, developed to study the physics of the growth and melt of ice at the ocean surface and the variations in ice extent, depend on the size of the time step. Thus, to study longer-term variations within a reasonable computer budget, a model with a scheme allowing longer time steps has been constructed. However, the results produced by the model can definitely depend on the length of the time step. The sensitivity of a model to time-step size can be reduced by appropriate approaches. The present investigation is concerned with experiments which use a formulation of a lead parameterization that can be considered as a first step toward the development of a lead parameterization suitable for a use in long-term climate studies.

  16. Aircraft conceptual design - an adaptable parametric sizing methodology

    NASA Astrophysics Data System (ADS)

    Coleman, Gary John, Jr.

    Aerospace is a maturing industry with successful and refined baselines which work well for traditional baseline missions, markets and technologies. However, when new markets (space tourism) or new constrains (environmental) or new technologies (composite, natural laminar flow) emerge, the conventional solution is not necessarily best for the new situation. Which begs the question "how does a design team quickly screen and compare novel solutions to conventional solutions for new aerospace challenges?" The answer is rapid and flexible conceptual design Parametric Sizing. In the product design life-cycle, parametric sizing is the first step in screening the total vehicle in terms of mission, configuration and technology to quickly assess first order design and mission sensitivities. During this phase, various missions and technologies are assessed. During this phase, the designer is identifying design solutions of concepts and configurations to meet combinations of mission and technology. This research undertaking contributes the state-of-the-art in aircraft parametric sizing through (1) development of a dedicated conceptual design process and disciplinary methods library, (2) development of a novel and robust parametric sizing process based on 'best-practice' approaches found in the process and disciplinary methods library, and (3) application of the parametric sizing process to a variety of design missions (transonic, supersonic and hypersonic transports), different configurations (tail-aft, blended wing body, strut-braced wing, hypersonic blended bodies, etc.), and different technologies (composite, natural laminar flow, thrust vectored control, etc.), in order to demonstrate the robustness of the methodology and unearth first-order design sensitivities to current and future aerospace design problems. This research undertaking demonstrates the importance of this early design step in selecting the correct combination of mission, technologies and configuration to

  17. An Adaptive Fourier Filter for Relaxing Time Stepping Constraints for Explicit Solvers

    SciTech Connect

    Gelb, Anne; Archibald, Richard K

    2015-01-01

    Filtering is necessary to stabilize piecewise smooth solutions. The resulting diffusion stabilizes the method, but may fail to resolve the solution near discontinuities. Moreover, high order filtering still requires cost prohibitive time stepping. This paper introduces an adaptive filter that controls spurious modes of the solution, but is not unnecessarily diffusive. Consequently we are able to stabilize the solution with larger time steps, but also take advantage of the accuracy of a high order filter.

  18. A new theory for multistep discretizations of stiff ordinary differential equations: Stability with large step sizes

    NASA Technical Reports Server (NTRS)

    Majda, G.

    1985-01-01

    A large set of variable coefficient linear systems of ordinary differential equations which possess two different time scales, a slow one and a fast one is considered. A small parameter epsilon characterizes the stiffness of these systems. A system of o.d.e.s. in this set is approximated by a general class of multistep discretizations which includes both one-leg and linear multistep methods. Sufficient conditions are determined under which each solution of a multistep method is uniformly bounded, with a bound which is independent of the stiffness of the system of o.d.e.s., when the step size resolves the slow time scale, but not the fast one. This property is called stability with large step sizes. The theory presented lets one compare properties of one-leg methods and linear multistep methods when they approximate variable coefficient systems of stiff o.d.e.s. In particular, it is shown that one-leg methods have better stability properties with large step sizes than their linear multistep counter parts. The theory also allows one to relate the concept of D-stability to the usual notions of stability and stability domains and to the propagation of errors for multistep methods which use large step sizes.

  19. Boosting the accuracy and speed of quantum Monte Carlo: Size consistency and time step

    NASA Astrophysics Data System (ADS)

    Zen, Andrea; Sorella, Sandro; Gillan, Michael J.; Michaelides, Angelos; Alfè, Dario

    2016-06-01

    Diffusion Monte Carlo (DMC) simulations for fermions are becoming the standard for providing high-quality reference data in systems that are too large to be investigated via quantum chemical approaches. DMC with the fixed-node approximation relies on modifications of the Green's function to avoid singularities near the nodal surface of the trial wave function. Here we show that these modifications affect the DMC energies in a way that is not size consistent, resulting in large time-step errors. Building on the modifications of Umrigar et al. and DePasquale et al. we propose a simple Green's function modification that restores size consistency to large values of the time step, which substantially reduces time-step errors. This algorithm also yields remarkable speedups of up to two orders of magnitude in the calculation of molecule-molecule binding energies and crystal cohesive energies, thus extending the horizons of what is possible with DMC.

  20. A marching-walking hybrid induces step length adaptation and transfers to natural walking.

    PubMed

    Long, Andrew W; Finley, James M; Bastian, Amy J

    2015-06-01

    Walking is highly adaptable to new demands and environments. We have previously studied adaptation of locomotor patterns via a split-belt treadmill, where subjects learn to walk with one foot moving faster than the other. Subjects learn to adapt their walking pattern by changing the location (spatial) and time (temporal) of foot placement. Here we asked whether we can induce adaptation of a specific walking pattern when one limb does not "walk" but instead marches in place (i.e., marching-walking hybrid). The marching leg's movement is limited during the stance phase, and thus certain sensory signals important for walking may be reduced. We hypothesized that this would produce a spatial-temporal strategy different from that of normal split-belt adaptation. Healthy subjects performed two experiments to determine whether they could adapt their spatial-temporal pattern of step lengths during the marching-walking hybrid and whether the learning transfers to over ground walking. Results showed that the hybrid group did adapt their step lengths, but the time course of adaptation and deadaption was slower than that for the split-belt group. We also observed that the hybrid group utilized a mostly spatial strategy whereas the split-belt group utilized both spatial and temporal strategies. Surprisingly, we found no significant difference between the hybrid and split-belt groups in over ground transfer. Moreover, the hybrid group retained more of the learned pattern when they returned to the treadmill. These findings suggest that physical rehabilitation with this marching-walking paradigm on conventional treadmills may produce changes in symmetry comparable to what is observed during split-belt training.

  1. A marching-walking hybrid induces step length adaptation and transfers to natural walking

    PubMed Central

    Long, Andrew W.; Finley, James M.

    2015-01-01

    Walking is highly adaptable to new demands and environments. We have previously studied adaptation of locomotor patterns via a split-belt treadmill, where subjects learn to walk with one foot moving faster than the other. Subjects learn to adapt their walking pattern by changing the location (spatial) and time (temporal) of foot placement. Here we asked whether we can induce adaptation of a specific walking pattern when one limb does not “walk” but instead marches in place (i.e., marching-walking hybrid). The marching leg's movement is limited during the stance phase, and thus certain sensory signals important for walking may be reduced. We hypothesized that this would produce a spatial-temporal strategy different from that of normal split-belt adaptation. Healthy subjects performed two experiments to determine whether they could adapt their spatial-temporal pattern of step lengths during the marching-walking hybrid and whether the learning transfers to over ground walking. Results showed that the hybrid group did adapt their step lengths, but the time course of adaptation and deadaption was slower than that for the split-belt group. We also observed that the hybrid group utilized a mostly spatial strategy whereas the split-belt group utilized both spatial and temporal strategies. Surprisingly, we found no significant difference between the hybrid and split-belt groups in over ground transfer. Moreover, the hybrid group retained more of the learned pattern when they returned to the treadmill. These findings suggest that physical rehabilitation with this marching-walking paradigm on conventional treadmills may produce changes in symmetry comparable to what is observed during split-belt training. PMID:25867742

  2. Stability with large step sizes for multistep discretizations of stiff ordinary differential equations

    NASA Technical Reports Server (NTRS)

    Majda, George

    1986-01-01

    One-leg and multistep discretizations of variable-coefficient linear systems of ODEs having both slow and fast time scales are investigated analytically. The stability properties of these discretizations are obtained independent of ODE stiffness and compared. The results of numerical computations are presented in tables, and it is shown that for large step sizes the stability of one-leg methods is better than that of the corresponding linear multistep methods.

  3. A cascade reaction network mimicking the basic functional steps of adaptive immune response

    NASA Astrophysics Data System (ADS)

    Han, Da; Wu, Cuichen; You, Mingxu; Zhang, Tao; Wan, Shuo; Chen, Tao; Qiu, Liping; Zheng, Zheng; Liang, Hao; Tan, Weihong

    2015-10-01

    Biological systems use complex ‘information-processing cores’ composed of molecular networks to coordinate their external environment and internal states. An example of this is the acquired, or adaptive, immune system (AIS), which is composed of both humoral and cell-mediated components. Here we report the step-by-step construction of a prototype mimic of the AIS that we call an adaptive immune response simulator (AIRS). DNA and enzymes are used as simple artificial analogues of the components of the AIS to create a system that responds to specific molecular stimuli in vitro. We show that this network of reactions can function in a manner that is superficially similar to the most basic responses of the vertebrate AIS, including reaction sequences that mimic both humoral and cellular responses. As such, AIRS provides guidelines for the design and engineering of artificial reaction networks and molecular devices.

  4. Effect of reaction-step-size noise on the switching dynamics of stochastic populations

    NASA Astrophysics Data System (ADS)

    Be'er, Shay; Heller-Algazi, Metar; Assaf, Michael

    2016-05-01

    In genetic circuits, when the messenger RNA lifetime is short compared to the cell cycle, proteins are produced in geometrically distributed bursts, which greatly affects the cellular switching dynamics between different metastable phenotypic states. Motivated by this scenario, we study a general problem of switching or escape in stochastic populations, where influx of particles occurs in groups or bursts, sampled from an arbitrary distribution. The fact that the step size of the influx reaction is a priori unknown and, in general, may fluctuate in time with a given correlation time and statistics, introduces an additional nondemographic reaction-step-size noise into the system. Employing the probability-generating function technique in conjunction with Hamiltonian formulation, we are able to map the problem in the leading order onto solving a stationary Hamilton-Jacobi equation. We show that compared to the "usual case" of single-step influx, bursty influx exponentially decreases the population's mean escape time from its long-lived metastable state. In particular, close to bifurcation we find a simple analytical expression for the mean escape time which solely depends on the mean and variance of the burst-size distribution. Our results are demonstrated on several realistic distributions and compare well with numerical Monte Carlo simulations.

  5. Vertebral Adaptations to Large Body Size in Theropod Dinosaurs

    PubMed Central

    Wilson, John P.; Woodruff, D. Cary; Gardner, Jacob D.; Flora, Holley M.; Horner, John R.; Organ, Chris L.

    2016-01-01

    Rugose projections on the anterior and posterior aspects of vertebral neural spines appear throughout Amniota and result from the mineralization of the supraspinous and interspinous ligaments via metaplasia, the process of permanent tissue-type transformation. In mammals, this metaplasia is generally pathological or stress induced, but is a normal part of development in some clades of birds. Such structures, though phylogenetically sporadic, appear throughout the fossil record of non-avian theropod dinosaurs, yet their physiological and adaptive significance has remained unexamined. Here we show novel histologic and phylogenetic evidence that neural spine projections were a physiological response to biomechanical stress in large-bodied theropod species. Metaplastic projections also appear to vary between immature and mature individuals of the same species, with immature animals either lacking them or exhibiting smaller projections, supporting the hypothesis that these structures develop through ontogeny as a result of increasing bending stress subjected to the spinal column. Metaplastic mineralization of spinal ligaments would likely affect the flexibility of the spinal column, increasing passive support for body weight. A stiff spinal column would also provide biomechanical support for the primary hip flexors and, therefore, may have played a role in locomotor efficiency and mobility in large-bodied species. This new association of interspinal ligament metaplasia in Theropoda with large body size contributes additional insight to our understanding of the diverse biomechanical coping mechanisms developed throughout Dinosauria, and stresses the significance of phylogenetic methods when testing for biological trends, evolutionary or not. PMID:27442509

  6. Analysis of steps adapted protocol in cardiac rehabilitation in the hospital phase

    PubMed Central

    Winkelmann, Eliane Roseli; Dallazen, Fernanda; Bronzatti, Angela Beerbaum Steinke; Lorenzoni, Juliara Cristina Werner; Windmöller, Pollyana

    2015-01-01

    Objective To analyze a cardiac rehabilitation adapted protocol in physical therapy during the postoperative hospital phase of cardiac surgery in a service of high complexity, in aspects regarded to complications and mortality prevalence and hospitalization days. Methods This is an observational cross-sectional, retrospective and analytical study performed by investigating 99 patients who underwent cardiac surgery for coronary artery bypass graft, heart valve replacement or a combination of both. Step program adapted for rehabilitation after cardiac surgery was analyzed under the command of the physiotherapy professional team. Results In average, a patient stays for two days in the Intensive Care Unit and three to four days in the hospital room, totalizing six days of hospitalization. Fatalities occurred in a higher percentage during hospitalization (5.1%) and up to two years period (8.6%) when compared to 30 days after hospital discharge (1.1%). Among the postoperative complications, the hemodynamic (63.4%) and respiratory (42.6%) were the most prevalent. 36-42% of complications occurred between the immediate postoperative period and the second postoperative day. The hospital discharge started from the fifth postoperative day. We can observe that in each following day, the patients are evolving in achieving the Steps, where Step 3 was the most used during the rehabilitation phase I. Conclusion This evolution program by steps can to guide the physical rehabilitation at the hospital in patients after cardiac surgery. PMID:25859866

  7. Exponential time-differencing with embedded Runge–Kutta adaptive step control

    SciTech Connect

    Whalen, P.; Brio, M.; Moloney, J.V.

    2015-01-01

    We have presented the first embedded Runge–Kutta exponential time-differencing (RKETD) methods of fourth order with third order embedding and fifth order with third order embedding for non-Rosenbrock type nonlinear systems. A procedure for constructing RKETD methods that accounts for both order conditions and stability is outlined. In our stability analysis, the fast time scale is represented by a full linear operator in contrast to particular scalar cases considered before. An effective time-stepping strategy based on reducing both ETD function evaluations and rejected steps is described. Comparisons of performance with adaptive-stepping integrating factor (IF) are carried out on a set of canonical partial differential equations: the shock-fronts of Burgers equation, interacting KdV solitons, KS controlled chaos, and critical collapse of two-dimensional NLS.

  8. Step-Detection and Adaptive Step-Length Estimation for Pedestrian Dead-Reckoning at Various Walking Speeds Using a Smartphone

    PubMed Central

    Ho, Ngoc-Huynh; Truong, Phuc Huu; Jeong, Gu-Min

    2016-01-01

    We propose a walking distance estimation method based on an adaptive step-length estimator at various walking speeds using a smartphone. First, we apply a fast Fourier transform (FFT)-based smoother on the acceleration data collected by the smartphone to remove the interference signals. Then, we analyze these data using a set of step-detection rules in order to detect walking steps. Using an adaptive estimator, which is based on a model of average step speed, we accurately obtain the walking step length. To evaluate the accuracy of the proposed method, we examine the distance estimation for four different distances and three speed levels. The experimental results show that the proposed method significantly outperforms conventional estimation methods in terms of accuracy. PMID:27598171

  9. Adaptive evolution and effective population size in wild house mice.

    PubMed

    Phifer-Rixey, Megan; Bonhomme, François; Boursot, Pierre; Churchill, Gary A; Piálek, Jaroslav; Tucker, Priscilla K; Nachman, Michael W

    2012-10-01

    Estimates of the proportion of amino acid substitutions that have been fixed by selection (α) vary widely among taxa, ranging from zero in humans to over 50% in Drosophila. This wide range may reflect differences in the efficacy of selection due to differences in the effective population size (N(e)). However, most comparisons have been made among distantly related organisms that differ not only in N(e) but also in many other aspects of their biology. Here, we estimate α in three closely related lineages of house mice that have a similar ecology but differ widely in N(e): Mus musculus musculus (N(e) ∼ 25,000-120,000), M. m. domesticus (N(e) ∼ 58,000-200,000), and M. m. castaneus (N(e) ∼ 200,000-733,000). Mice were genotyped using a high-density single nucleotide polymorphism array, and the proportions of replacement and silent mutations within subspecies were compared with those fixed between each subspecies and an outgroup, Mus spretus. There was significant evidence of positive selection in M. m. castaneus, the lineage with the largest N(e), with α estimated to be approximately 40%. In contrast, estimates of α for M. m. domesticus (α = 13%) and for M. m. musculus (α = 12 %) were much smaller. Interestingly, the higher estimate of α for M. m. castaneus appears to reflect not only more adaptive fixations but also more effective purifying selection. These results support the hypothesis that differences in N(e) contribute to differences among species in the efficacy of selection.

  10. Simulation step size analysis of a whole-cell computational model of bacteria

    NASA Astrophysics Data System (ADS)

    Abreu, Raphael; Castro, Maria Clicia S.; Silva, Fabrício Alves B.

    2016-12-01

    Understanding how complex phenotypes arise from individual molecules and their interactions is a major challenge in biology and, to meet this challenge, computational approaches are increasingly employed. As an example, a recent paper [1] proposed a whole-cell model Mycoplasma genitalium including all cell components and their interactions. 28 modules representing several cell functions were modeled independently, and then integrated into a single computational model. One assumption considered in the whole-cell model of M.Genitalium is that all 28 modules can be modeled independently given the 1 second step size used in simulations. This is a major assumption, since it simplifies the modeling of several cell functions and makes the modeling of the system as a whole feasible. In this paper we investigate the dependency of experimental results on that assumption. We have simulated the M.Genitalium cell cycle using several simulation time step sizes and compared the results to the ones obtained with the system using 1 second simulation time step.

  11. One-step synthesis of hybrid inorganic-organic nanocomposite coatings by novel laser adaptive ablation deposition technique

    NASA Astrophysics Data System (ADS)

    Serbezov, Valery; Sotirov, Sotir

    2013-03-01

    A novel approach for one-step synthesis of hybrid inorganic-organic nanocomposite coatings by new modification of Pulsed Laser Deposition technology called Laser Adaptive Ablation Deposition (LAAD) is presented. Hybrid nanocomposite coatings including Mg- Rapamycin and Mg- Desoximetasone were produced by UV TEA N2 laser under low vacuum (0.1 Pa) and room temperature onto substrates from SS 316L, KCl and NaCl. The laser fluence for Mg alloy was 1, 8 J/cm2 and for Desoximetasone 0,176 J/cm2 and for Rapamycin 0,118 J/cm2 were respectively. The threedimensional two-segmented single target was used to adapt the interaction of focused laser beam with inorganic and organic material. Magnesium alloy nanoparticles with sizes from 50 nm to 250 nm were obtained in organic matrices. The morphology of nanocomposites films were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Fourier Transform Infrared (FTIR) spectroscopy measurements were applied in order to study the functional properties of organic component before and after the LAAD process. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of Mg alloy presence in hybrid nanocomposites coatings. The precise control of process parameters and particularly of the laser fluence adjustment enables transfer on materials with different physical chemical properties and one-step synthesis of complex inorganic- organic nanocomposites coatings.

  12. Sample size calculation for stepped wedge and other longitudinal cluster randomised trials.

    PubMed

    Hooper, Richard; Teerenstra, Steven; de Hoop, Esther; Eldridge, Sandra

    2016-11-20

    The sample size required for a cluster randomised trial is inflated compared with an individually randomised trial because outcomes of participants from the same cluster are correlated. Sample size calculations for longitudinal cluster randomised trials (including stepped wedge trials) need to take account of at least two levels of clustering: the clusters themselves and times within clusters. We derive formulae for sample size for repeated cross-section and closed cohort cluster randomised trials with normally distributed outcome measures, under a multilevel model allowing for variation between clusters and between times within clusters. Our formulae agree with those previously described for special cases such as crossover and analysis of covariance designs, although simulation suggests that the formulae could underestimate required sample size when the number of clusters is small. Whether using a formula or simulation, a sample size calculation requires estimates of nuisance parameters, which in our model include the intracluster correlation, cluster autocorrelation, and individual autocorrelation. A cluster autocorrelation less than 1 reflects a situation where individuals sampled from the same cluster at different times have less correlated outcomes than individuals sampled from the same cluster at the same time. Nuisance parameters could be estimated from time series obtained in similarly clustered settings with the same outcome measure, using analysis of variance to estimate variance components. Copyright © 2016 John Wiley & Sons, Ltd.

  13. A 10-step safety management framework for construction small and medium-sized enterprises.

    PubMed

    Gunduz, Murat; Laitinen, Heikki

    2016-07-20

    It is of great importance to develop an occupational health and safety management system (OHS MS) to form a systemized approach to improve health and safety. It is a known fact that thousands of accidents and injuries occur in the construction industry. Most of these accidents occur in small and medium-sized enterprises (SMEs). This article provides a 10-step user-friendly OHS MS for the construction industry. A quantitative OHS MS indexing method is also introduced in the article. The practical application of the system to real SMEs and its promising results are also presented.

  14. A Three-Step Approach with Adaptive Additive Magnitude Selection for the Sharpening of Images

    PubMed Central

    Lee, Tien-Lin

    2014-01-01

    Aimed to find the additive magnitude automatically and adaptively, we propose a three-step and model-based approach for the sharpening of images in this paper. In the first pass, a Grey prediction model is applied to find a global maximal additive magnitude so that the condition of oversharpening in images to be sharpened can be avoided. During the second pass, edge pixels are picked out with our previously proposed edge detection mechanism. In this pass, a low-pass filter is also applied so that isolated pixels will not be regarded as around an edge. In the final pass, those pixels detected as around an edge are adjusted adaptively based on the local statistics, and those nonedge pixels are kept unaltered. Extensive experiments on natural images as well as medical images with subjective and objective evaluations will be given to demonstrate the usefulness of the proposed approach. PMID:25309951

  15. A Robust Diffusion Estimation Algorithm with Self-Adjusting Step-Size in WSNs.

    PubMed

    Shao, Xiaodan; Chen, Feng; Ye, Qing; Duan, Shukai

    2017-04-10

    In wireless sensor networks (WSNs), each sensor node can estimate the global parameter from the local data in a distributed manner. This paper proposed a robust diffusion estimation algorithm based on a minimum error entropy criterion with a self-adjusting step-size, which are referred to as the diffusion MEE-SAS (DMEE-SAS) algorithm. The DMEE-SAS algorithm has a fast speed of convergence and is robust against non-Gaussian noise in the measurements. The detailed performance analysis of the DMEE-SAS algorithm is performed. By combining the DMEE-SAS algorithm with the diffusion minimum error entropy (DMEE) algorithm, an Improving DMEE-SAS algorithm is proposed for a non-stationary environment where tracking is very important. The Improving DMEE-SAS algorithm can avoid insensitivity of the DMEE-SAS algorithm due to the small effective step-size near the optimal estimator and obtain a fast convergence speed. Numerical simulations are given to verify the effectiveness and advantages of these proposed algorithms.

  16. Adaptive multi-step Full Waveform Inversion based on Waveform Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Hu, Yong; Han, Liguo; Xu, Zhuo; Zhang, Fengjiao; Zeng, Jingwen

    2017-04-01

    Full Waveform Inversion (FWI) can be used to build high resolution velocity models, but there are still many challenges in seismic field data processing. The most difficult problem is about how to recover long-wavelength components of subsurface velocity models when seismic data is lacking of low frequency information and without long-offsets. To solve this problem, we propose to use Waveform Mode Decomposition (WMD) method to reconstruct low frequency information for FWI to obtain a smooth model, so that the initial model dependence of FWI can be reduced. In this paper, we use adjoint-state method to calculate the gradient for Waveform Mode Decomposition Full Waveform Inversion (WMDFWI). Through the illustrative numerical examples, we proved that the low frequency which is reconstructed by WMD method is very reliable. WMDFWI in combination with the adaptive multi-step inversion strategy can obtain more faithful and accurate final inversion results. Numerical examples show that even if the initial velocity model is far from the true model and lacking of low frequency information, we still can obtain good inversion results with WMD method. From numerical examples of anti-noise test, we see that the adaptive multi-step inversion strategy for WMDFWI has strong ability to resist Gaussian noise. WMD method is promising to be able to implement for the land seismic FWI, because it can reconstruct the low frequency information, lower the dominant frequency in the adjoint source, and has a strong ability to resist noise.

  17. Effective population size is positively correlated with levels of adaptive divergence among annual sunflowers.

    PubMed

    Strasburg, Jared L; Kane, Nolan C; Raduski, Andrew R; Bonin, Aurélie; Michelmore, Richard; Rieseberg, Loren H

    2011-05-01

    The role of adaptation in the divergence of lineages has long been a central question in evolutionary biology, and as multilocus sequence data sets have become available for a wide range of taxa, empirical estimates of levels of adaptive molecular evolution are increasingly common. Estimates vary widely among taxa, with high levels of adaptive evolution in Drosophila, bacteria, and viruses but very little evidence of widespread adaptive evolution in hominids. Although estimates in plants are more limited, some recent work has suggested that rates of adaptive evolution in a range of plant taxa are surprisingly low and that there is little association between adaptive evolution and effective population size in contrast to patterns seen in other taxa. Here, we analyze data from 35 loci for six sunflower species that vary dramatically in effective population size. We find that rates of adaptive evolution are positively correlated with effective population size in these species, with a significant fraction of amino acid substitutions driven by positive selection in the species with the largest effective population sizes but little or no evidence of adaptive evolution in species with smaller effective population sizes. Although other factors likely contribute as well, in sunflowers effective population size appears to be an important determinant of rates of adaptive evolution.

  18. Comparing adaptive stepped care and monetary-based voucher interventions for opioid dependence.

    PubMed

    Brooner, Robert K; Kidorf, Michael S; King, Van L; Stoller, Kenneth B; Neufeld, Karin J; Kolodner, Ken

    2007-05-01

    This 6-month randomized clinical trial (with 3-month follow-up) used a 2x2 design to compare the independent and combined effectiveness of two interventions designed to improve outcomes in treatment-seeking opioid dependent patients (n=236): motivated stepped care (MSC) and contingent voucher incentives (CVI). MSC is an adaptive treatment strategy that uses principles of negative reinforcement and avoidance to motivate both attendance to varying levels of counseling services and brief periods of abstinence [Brooner, R.K., Kidorf, M., 2002. Using behavioral reinforcement to improve methadone treatment participation. Sci. Pract. Perspect. 1, 38-46; Brooner, R.K., Kidorf, M.S., King, V.L., Peirce, J.M., Bigelow, G.E., Kolodner, K., 2004. A modified "stepped care" approach to improve attendance behavior in treatment seeking opioid abusers. J. Subst. Abuse Treat. 27, 223-232]. In contrast, CVI [Higgins, S., Delaney, D.D., Budney, A.J., Bickel, W.K., Hughes, J.R., Foerg, B.A., Fenwick, J.W., 1991. A behavioral approach to achieving initial cocaine abstinence. Am. Psychiatr. 148, 1218-1224] relies on positive reinforcement to motivate drug abstinence. The results showed that the combined approach (MSC+CVI) was associated with the highest proportion of drug-negative urine samples during both the randomized and 3-month follow-up arms of the evaluation. The CVI-only and the MSC-only conditions evidenced similar proportions of drug-negative urine samples that were both significantly greater than the standard care (SC) comparison group. Voucher-based reinforcement was associated with better retention, while adaptive stepped-based care was associated with better adherence to scheduled counseling sessions. These results suggest that both CVI and MSC are more effective than routine care for reducing drug use in opioid dependent outpatients, and that the overall benefits of MSC are enhanced further by adding positive reinforcement.

  19. A New Modified Artificial Bee Colony Algorithm with Exponential Function Adaptive Steps.

    PubMed

    Mao, Wei; Lan, Heng-You; Li, Hao-Ru

    2016-01-01

    As one of the most recent popular swarm intelligence techniques, artificial bee colony algorithm is poor at exploitation and has some defects such as slow search speed, poor population diversity, the stagnation in the working process, and being trapped into the local optimal solution. The purpose of this paper is to develop a new modified artificial bee colony algorithm in view of the initial population structure, subpopulation groups, step updating, and population elimination. Further, depending on opposition-based learning theory and the new modified algorithms, an improved S-type grouping method is proposed and the original way of roulette wheel selection is substituted through sensitivity-pheromone way. Then, an adaptive step with exponential functions is designed for replacing the original random step. Finally, based on the new test function versions CEC13, six benchmark functions with the dimensions D = 20 and D = 40 are chosen and applied in the experiments for analyzing and comparing the iteration speed and accuracy of the new modified algorithms. The experimental results show that the new modified algorithm has faster and more stable searching and can quickly increase poor population diversity and bring out the global optimal solutions.

  20. A New Modified Artificial Bee Colony Algorithm with Exponential Function Adaptive Steps

    PubMed Central

    Mao, Wei; Li, Hao-ru

    2016-01-01

    As one of the most recent popular swarm intelligence techniques, artificial bee colony algorithm is poor at exploitation and has some defects such as slow search speed, poor population diversity, the stagnation in the working process, and being trapped into the local optimal solution. The purpose of this paper is to develop a new modified artificial bee colony algorithm in view of the initial population structure, subpopulation groups, step updating, and population elimination. Further, depending on opposition-based learning theory and the new modified algorithms, an improved S-type grouping method is proposed and the original way of roulette wheel selection is substituted through sensitivity-pheromone way. Then, an adaptive step with exponential functions is designed for replacing the original random step. Finally, based on the new test function versions CEC13, six benchmark functions with the dimensions D = 20 and D = 40 are chosen and applied in the experiments for analyzing and comparing the iteration speed and accuracy of the new modified algorithms. The experimental results show that the new modified algorithm has faster and more stable searching and can quickly increase poor population diversity and bring out the global optimal solutions. PMID:27293426

  1. Effects of reinforcer quality and step size on rats' performance under progressive ratio schedules.

    PubMed

    Covarrubias, Pablo; Aparicio, Carlos F

    2008-06-01

    The Mathematical Principles of Reinforcement (MPR) model accurately predicts performance in fixed ratio (FR) schedules of reinforcement. The aim of the present study was to assess the generality of MPR with rats responding under progressive ratio (PR) schedules of different step sizes (PR1 or PR3) that provided either food or saccharin pellets. The results showed that the rats responding for saccharin pellets produced higher breakpoints (i.e., completed higher ratios) than those responding for food pellets. In terms of theoretical parameters, one finding unanticipated on the basis of MPR was that the a parameter (specific activation) was higher for the PR3 schedules. This finding suggests that specific activation may be affected indirectly by motor parameters of the task.

  2. One-step synthesis of FePt nanoparticles with tunable size.

    PubMed

    Chen, Min; Liu, J P; Sun, Shouheng

    2004-07-14

    A one-step synthesis of FePt nanoparticles is reported. The size, composition, and shape of the particles are controlled by varying the synthetic parameters such as molar ratio of stabilizers to metal precursor, addition sequence of the stabilizers and metal precursors, heating rate, heating temperature, and heating duration. An assembly of large (6 nm or greater) FePt nanoparticles, especially oxide-coated FePt nanoparticles, can sustain higher temperature (up to 650 degrees C) annealing without noticeable particle sintering. Room temperature coercivity of an assembly containing discrete FePt dots can reach as high as 1.3 T, a value that is suitable for hard magnetic applications.

  3. Discrete Step Sizes of Molecular Motors Lead to Bimodal Non-Gaussian Velocity Distributions under Force.

    PubMed

    Vu, Huong T; Chakrabarti, Shaon; Hinczewski, Michael; Thirumalai, D

    2016-08-12

    Fluctuations in the physical properties of biological machines are inextricably linked to their functions. Distributions of run lengths and velocities of processive molecular motors, like kinesin-1, are accessible through single-molecule techniques, but rigorous theoretical models for these probabilities are lacking. Here, we derive exact analytic results for a kinetic model to predict the resistive force (F)-dependent velocity [P(v)] and run length [P(n)] distribution functions of generic finitely processive molecular motors. Our theory quantitatively explains the zero force kinesin-1 data for both P(n) and P(v) using the detachment rate as the only parameter. In addition, we predict the F dependence of these quantities. At nonzero F, P(v) is non-Gaussian and is bimodal with peaks at positive and negative values of v, which is due to the discrete step size of kinesin-1. Although the predictions are based on analyses of kinesin-1 data, our results are general and should hold for any processive motor, which walks on a track by taking discrete steps.

  4. Discrete Step Sizes of Molecular Motors Lead to Bimodal Non-Gaussian Velocity Distributions under Force

    NASA Astrophysics Data System (ADS)

    Vu, Huong T.; Chakrabarti, Shaon; Hinczewski, Michael; Thirumalai, D.

    2016-08-01

    Fluctuations in the physical properties of biological machines are inextricably linked to their functions. Distributions of run lengths and velocities of processive molecular motors, like kinesin-1, are accessible through single-molecule techniques, but rigorous theoretical models for these probabilities are lacking. Here, we derive exact analytic results for a kinetic model to predict the resistive force (F )-dependent velocity [P (v )] and run length [P (n )] distribution functions of generic finitely processive molecular motors. Our theory quantitatively explains the zero force kinesin-1 data for both P (n ) and P (v ) using the detachment rate as the only parameter. In addition, we predict the F dependence of these quantities. At nonzero F , P (v ) is non-Gaussian and is bimodal with peaks at positive and negative values of v , which is due to the discrete step size of kinesin-1. Although the predictions are based on analyses of kinesin-1 data, our results are general and should hold for any processive motor, which walks on a track by taking discrete steps.

  5. 40 CFR 141.81 - Applicability of corrosion control treatment steps to small, medium-size and large water systems.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... treatment steps to small, medium-size and large water systems. 141.81 Section 141.81 Protection of... WATER REGULATIONS Control of Lead and Copper § 141.81 Applicability of corrosion control treatment steps... review and approve the addition of a new source or long-term change in water treatment before it...

  6. 40 CFR 141.81 - Applicability of corrosion control treatment steps to small, medium-size and large water systems.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... treatment steps to small, medium-size and large water systems. 141.81 Section 141.81 Protection of... WATER REGULATIONS Control of Lead and Copper § 141.81 Applicability of corrosion control treatment steps... review and approve the addition of a new source or long-term change in water treatment before it...

  7. 40 CFR 141.81 - Applicability of corrosion control treatment steps to small, medium-size and large water systems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... treatment steps to small, medium-size and large water systems. 141.81 Section 141.81 Protection of... WATER REGULATIONS Control of Lead and Copper § 141.81 Applicability of corrosion control treatment steps... review and approve the addition of a new source or long-term change in water treatment before it...

  8. Structured estimation - Sample size reduction for adaptive pattern classification

    NASA Technical Reports Server (NTRS)

    Morgera, S.; Cooper, D. B.

    1977-01-01

    The Gaussian two-category classification problem with known category mean value vectors and identical but unknown category covariance matrices is considered. The weight vector depends on the unknown common covariance matrix, so the procedure is to estimate the covariance matrix in order to obtain an estimate of the optimum weight vector. The measure of performance for the adapted classifier is the output signal-to-interference noise ratio (SIR). A simple approximation for the expected SIR is gained by using the general sample covariance matrix estimator; this performance is both signal and true covariance matrix independent. An approximation is also found for the expected SIR obtained by using a Toeplitz form covariance matrix estimator; this performance is found to be dependent on both the signal and the true covariance matrix.

  9. Two-step Adaptive Management for choosing between two management actions.

    PubMed

    Moore, Alana L; Walker, Leila; Runge, Michael C; McDonald-Madden, Eve; McCarthy, Michael A

    2017-01-31

    Adaptive management is widely advocated to improve environmental management. Derivations of optimal strategies for adaptive management, however, tend to be case specific and time consuming. In contrast, managers might seek relatively simple guidance, such as insight into when a new potential management action should be considered, and how much effort should be expended on trialing such an action. We constructed a two time-step scenario where a manager is choosing between two possible management actions. The manager has a total budget which can be split between a learning phase and an implementation phase. We use this scenario to investigate when and how much a manager should invest in learning about the management actions available. The optimal investment in learning can be understood intuitively by accounting for the expected value of sample information, the benefits that accrue during learning, the direct costs of learning, and the opportunity costs of learning. We find that the optimal proportion of the budget to spend on learning is characterized by several critical thresholds that mark a jump from spending a large proportion of the budget on learning to spending nothing. For example, as sampling variance increases it is optimal to spend a larger proportion of the budget on learning, up to a point - if the sampling variance passes a critical threshold, it is no longer beneficial to invest in learning. Similar thresholds are observed as a function of the total budget and the difference in the expected performance of the two actions. We illustrate how this model can be applied using a case study of choosing between alternative rearing diets for hihi, an endangered New Zealand passerine. Although the model presented is a simplified scenario, we believe it is relevant to many management situations. Managers often have relatively short time horizons for management, and might be reluctant to consider further investment in learning and monitoring beyond collecting

  10. Effects of Class Size and Adaptive Teaching Competency on Classroom Processes and Academic Outcome

    ERIC Educational Resources Information Center

    Bruhwiler, Christian; Blatchford, Peter

    2011-01-01

    In many studies of class size effects, teacher characteristics are missing, even though many argue it is not class size that is important but teacher quality. In the present study teachers' effectiveness on the learning progress was assessed while teaching a unit with predefined learning objectives. To measure adaptive teaching competency a…

  11. Adaptability of stride-to-stride control of stepping movements in human walking.

    PubMed

    Bohnsack-McLagan, Nicole K; Cusumano, Joseph P; Dingwell, Jonathan B

    2016-01-25

    Humans continually adapt their movements as they walk on different surfaces, avoid obstacles, etc. External (environmental) and internal (physiological) noise-like disturbances, and the responses that correct for them, each contribute to locomotor variability. This variability may sometimes be detrimental (perhaps increasing fall risk), or sometimes beneficial (perhaps reflecting exploration of multiple task solutions). Here, we determined how humans regulated stride-to-stride fluctuations in walking when presented different task goals that allowed them to exploit inherent redundancies in different ways. Fourteen healthy adults walked on a treadmill under each of four conditions: constant speed only (SPD), constant speed and stride length (LEN), constant speed and stride time (TIM), or constant speed, stride length, and stride time (ALL). Multiple analyses tested competing hypotheses that participants might attempt to either equally satisfy all goals simultaneously, or instead adopt systematic intermediate strategies that only partly satisfied each individual goal. Participants exhibited similar average stepping behavior, but significant differences in variability and stride-to-stride serial correlations across conditions. Analyses of the structure of stride-to-stride fluctuation dynamics demonstrated humans resolved the competing goals presented not by minimizing errors equally with respect to all goals, but instead by trying to only partly satisfy each goal. Thus, humans exploit task redundancies even when they are explicitly removed from the task specifications. These findings may help identify when variability is predictive of, or protective against, fall risk. They may also help inform rehabilitation interventions to better exploit the positive contributions of variability, while minimizing the negative.

  12. Adaptive Protein Evolution in Animals and the Effective Population Size Hypothesis

    PubMed Central

    Galtier, Nicolas

    2016-01-01

    The rate at which genomes adapt to environmental changes and the prevalence of adaptive processes in molecular evolution are two controversial issues in current evolutionary genetics. Previous attempts to quantify the genome-wide rate of adaptation through amino-acid substitution have revealed a surprising diversity of patterns, with some species (e.g. Drosophila) experiencing a very high adaptive rate, while other (e.g. humans) are dominated by nearly-neutral processes. It has been suggested that this discrepancy reflects between-species differences in effective population size. Published studies, however, were mainly focused on model organisms, and relied on disparate data sets and methodologies, so that an overview of the prevalence of adaptive protein evolution in nature is currently lacking. Here we extend existing estimators of the amino-acid adaptive rate by explicitly modelling the effect of favourable mutations on non-synonymous polymorphism patterns, and we apply these methods to a newly-built, homogeneous data set of 44 non-model animal species pairs. Data analysis uncovers a major contribution of adaptive evolution to the amino-acid substitution process across all major metazoan phyla—with the notable exception of humans and primates. The proportion of adaptive amino-acid substitution is found to be positively correlated to species effective population size. This relationship, however, appears to be primarily driven by a decreased rate of nearly-neutral amino-acid substitution because of more efficient purifying selection in large populations. Our results reveal that adaptive processes dominate the evolution of proteins in most animal species, but do not corroborate the hypothesis that adaptive substitutions accumulate at a faster rate in large populations. Implications regarding the factors influencing the rate of adaptive evolution and positive selection detection in humans vs. other organisms are discussed. PMID:26752180

  13. "So We Adapt Step by Step": Acculturation experiences affecting diabetes management and perceived health for Chinese American immigrants.

    PubMed

    Chun, Kevin M; Chesla, Catherine A; Kwan, Christine M L

    2011-01-01

    This study examines how acculturation affects type 2 diabetes management and perceived health for Chinese American immigrants in the U.S. Acculturation experiences or cultural adaptation experiences affecting diabetes management and health were solicited from an informant group of immigrant patients and their spouses (N = 40) during group, couple and individual interviews conducted from 2005 to 2008. A separate respondent group of immigrant patients and their spouses (N = 19) meeting inclusion criteria reviewed and confirmed themes generated by the informant group. Using interpretive phenomenology, three key themes in patients' and spouses' acculturation experiences were identified: a) utilizing health care, b) maintaining family relations and roles, and c) establishing community ties and groundedness in the U.S. Acculturation experiences reflecting these themes were broad in scope and not fully captured by current self-report and proxy acculturation measures. In the current study, shifting family roles and evaluations of diabetes care and physical environment in the U.S. significantly affected diabetes management and health, yet are overlooked in acculturation and health investigations. Furthermore, the salience and impact of specific acculturation experiences respective to diabetes management and perceived health varied across participants due to individual, family, developmental, and environmental factors. In regards to salience, maintaining filial and interdependent family relations in the U.S. was of particular concern for older participants and coping with inadequate health insurance in the U.S. was especially distressing for self-described lower-middle to middle-class participants. In terms of impact, family separation and relocating to ethnically similar neighborhoods in the U.S. differentially affected diabetes management and health due to participants' varied family relations and pre-migration family support levels and diverse cultural and linguistic

  14. Simulation and experimental design of a new advanced variable step size Incremental Conductance MPPT algorithm for PV systems.

    PubMed

    Loukriz, Abdelhamid; Haddadi, Mourad; Messalti, Sabir

    2016-05-01

    Improvement of the efficiency of photovoltaic system based on new maximum power point tracking (MPPT) algorithms is the most promising solution due to its low cost and its easy implementation without equipment updating. Many MPPT methods with fixed step size have been developed. However, when atmospheric conditions change rapidly , the performance of conventional algorithms is reduced. In this paper, a new variable step size Incremental Conductance IC MPPT algorithm has been proposed. Modeling and simulation of different operational conditions of conventional Incremental Conductance IC and proposed methods are presented. The proposed method was developed and tested successfully on a photovoltaic system based on Flyback converter and control circuit using dsPIC30F4011. Both, simulation and experimental design are provided in several aspects. A comparative study between the proposed variable step size and fixed step size IC MPPT method under similar operating conditions is presented. The obtained results demonstrate the efficiency of the proposed MPPT algorithm in terms of speed in MPP tracking and accuracy.

  15. 40 CFR 141.81 - Applicability of corrosion control treatment steps to small, medium-size and large water systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 23 2011-07-01 2011-07-01 false Applicability of corrosion control... WATER REGULATIONS Control of Lead and Copper § 141.81 Applicability of corrosion control treatment steps to small, medium-size and large water systems. (a) Systems shall complete the applicable...

  16. 40 CFR 141.81 - Applicability of corrosion control treatment steps to small, medium-size and large water systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Applicability of corrosion control... WATER REGULATIONS Control of Lead and Copper § 141.81 Applicability of corrosion control treatment steps to small, medium-size and large water systems. (a) Systems shall complete the applicable...

  17. Adaptive and nonadaptive genome size evolution in Karst endemic flora of China.

    PubMed

    Kang, Ming; Tao, Junjie; Wang, Jing; Ren, Chen; Qi, Qingwen; Xiang, Qiu-Yun; Huang, Hongwen

    2014-06-01

    Genome size variation is of fundamental biological importance and has been a longstanding puzzle in evolutionary biology. Several hypotheses for genome size evolution including neutral, maladaptive, and adaptive models have been proposed, but the relative importance of these models remains controversial. Primulina is a genus that is highly diversified in the Karst region of southern China, where genome size variation and the underlying evolutionary mechanisms are poorly understood. We reconstructed the phylogeny of Primulina using DNA sequences for 104 species and determined the genome sizes of 101 species. We examined the phylogenetic signal in genome size variation, and tested the fit to different evolutionary models and for correlations with variation in latitude and specific leaf area (SLA). The results showed that genome size, SLA and latitudinal variation all displayed strong phylogenetic signals, but were best explained by different evolutionary models. Furthermore, significant positive relationships were detected between genome size and SLA and between genome size and latitude. Our study is the first to investigate genome size evolution on such a comprehensive scale and in the Karst region flora. We conclude that genome size in Primulina is phylogenetically conserved but its variation among species is a combined outcome of both neutral and adaptive evolution.

  18. Diminishing Returns of Population Size in the Rate of RNA Virus Adaptation

    PubMed Central

    Miralles, Rosario; Moya, Andrés; Elena, Santiago F.

    2000-01-01

    Whenever an asexual viral population evolves by adapting to new environmental conditions, beneficial mutations, the ultimate cause of adaptation, are randomly produced and then fixed in the population. The larger the population size and the higher the mutation rate, the more beneficial mutations can be produced per unit time. With the usually high mutation rate of RNA viruses and in a large enough population, several beneficial mutations could arise at the same time but in different genetic backgrounds, and if the virus is asexual, they will never be brought together through recombination. Thus, the best of these genotypes must outcompete each other on their way to fixation. This competition among beneficial mutations has the effect of slowing the overall rate of adaptation. This phenomenon is known as clonal interference. Clonal interference predicts a speed limit for adaptation as the population size increases. In the present report, by varying the size of evolving vesicular stomatitis virus populations, we found evidence clearly demonstrating this speed limit and thus indicating that clonal interference might be an important factor modulating the rate of adaptation to an in vitro cell system. Several evolutionary and epidemiological implications of the clonal interference model applied to RNA viruses are discussed. PMID:10729131

  19. Adaptive Fraunhofer diffraction particle sizing instrument using a spatial light modulator.

    PubMed

    Hirleman, E D; Dellenback, P A

    1989-11-15

    Integration of a magnetooptic spatial light modulator into a Fraunhofer diffraction particle sizing instrument is proposed and demonstrated theoretically and experimentally. The concept gives the instrument the ability to reconfigure a detector array on-line and thereby adapt to the measurement context.

  20. Increased Back-Bonding Explains Step-Edge Reactivity and Particle Size Effect for CO Activation on Ru Nanoparticles.

    PubMed

    Foppa, Lucas; Copéret, Christophe; Comas-Vives, Aleix

    2016-12-28

    Carbon monoxide is a ubiquitous molecule, a key feedstock and intermediate in chemical processes. Its adsorption and activation, typically carried out on metallic nanoparticles (NPs), are strongly dependent on the particle size. In particular, small NPs, which in principle contain more corner and step-edge atoms, are surprisingly less reactive than larger ones. Hereby, first-principles calculations on explicit Ru NP models (1-2 nm) show that both small and large NPs can present step-edge sites (e.g., B5 and B6 sites). However, such sites display strong particle-size-dependent reactivity because of very subtle differences in local chemical bonding. State-of-the-art crystal orbital Hamilton population analysis allows a detailed molecular orbital picture of adsorbed CO on step-edges, which can be classified as flat (η(1) coordination) and concave (η(2) coordination) sites. Our analysis shows that the CO π-metal dπ hybrid band responsible for the electron back-donation is better represented by an oxygen lone pair on flat sites, whereas it is delocalized on both C and O atoms on concave sites, increasing the back-bonding on these sites compared to flat step-edges or low-index surface sites. The bonding analysis also rationalizes why CO cleavage is easier on step-edge sites of large NPs compared to small ones irrespective of the site geometry. The lower reactivity of small NPs is due to the smaller extent of the Ru-O interaction in the η(2) adsorption mode, which destabilizes the η(2) transition-state structure for CO direct cleavage. Our findings provide a molecular understanding of the reactivity of CO on NPs, which is consistent with the observed particle size effect.

  1. Maximum type 1 error rate inflation in multiarmed clinical trials with adaptive interim sample size modifications.

    PubMed

    Graf, Alexandra C; Bauer, Peter; Glimm, Ekkehard; Koenig, Franz

    2014-07-01

    Sample size modifications in the interim analyses of an adaptive design can inflate the type 1 error rate, if test statistics and critical boundaries are used in the final analysis as if no modification had been made. While this is already true for designs with an overall change of the sample size in a balanced treatment-control comparison, the inflation can be much larger if in addition a modification of allocation ratios is allowed as well. In this paper, we investigate adaptive designs with several treatment arms compared to a single common control group. Regarding modifications, we consider treatment arm selection as well as modifications of overall sample size and allocation ratios. The inflation is quantified for two approaches: a naive procedure that ignores not only all modifications, but also the multiplicity issue arising from the many-to-one comparison, and a Dunnett procedure that ignores modifications, but adjusts for the initially started multiple treatments. The maximum inflation of the type 1 error rate for such types of design can be calculated by searching for the "worst case" scenarios, that are sample size adaptation rules in the interim analysis that lead to the largest conditional type 1 error rate in any point of the sample space. To show the most extreme inflation, we initially assume unconstrained second stage sample size modifications leading to a large inflation of the type 1 error rate. Furthermore, we investigate the inflation when putting constraints on the second stage sample sizes. It turns out that, for example fixing the sample size of the control group, leads to designs controlling the type 1 error rate.

  2. Size differentiation in Finnish house sparrows follows Bergmann's rule with evidence of local adaptation.

    PubMed

    Brommer, J E; Hanski, I K; Kekkonen, J; Väisänen, R A

    2014-04-01

    Bergmann's rule predicts that individuals are larger in more poleward populations and that this size gradient has an adaptive basis. Hence, phenotypic divergence in size traits between populations (PST ) is expected to exceed the level of divergence by drift alone (FST ). We measured 16 skeletal traits, body mass and wing length in 409 male and 296 female house sparrows Passer domesticus sampled in 12 populations throughout Finland, where the species has its northernmost European distributional margin. Morphometric differentiation across populations (PST ) was compared with differentiation in 13 microsatellites (FST ). We find that twelve traits phenotypically diverged more than FST in both sexes, and an additional two traits diverged in males. The phenotypic divergence exceeded FST in several traits to such a degree that findings were robust also to strong between-population environmental effects. Divergence was particularly strong in dimensions of the bill, making it a strong candidate for the study of adaptive molecular genetic divergence. Divergent traits increased in size in more northern populations. We conclude that house sparrows show evidence of an adaptive latitudinal size gradient consistent with Bergmann's rule on the modest spatial scale of ca. 600 km.

  3. Clinical efforts to reduce myocardial infarct size--the next step.

    PubMed

    Braunwald, Eugene

    2011-01-01

    Prompt myocardial reperfusion reduces infarct size in patients experiencing coronary occlusion. However, its clinical value is limited because reperfusion also causes ischemic myocardial reperfusion injury (IMRI). Considerable research to reduce IMRI has been conducted. Three interventions appear to be promising: 1) myocardial conditioning, which consists of repetitive occlusions of coronary or other arteries prior to or at the time of myocardial reperfusion; 2) the administration of cyclosporine A; and 3) the administration of adenosine. A plan for the testing of these interventions in patients with acute myocardial infarction is described.

  4. On the performance of voltage stepping for the simulation of adaptive, nonlinear integrate-and-fire neuronal networks.

    PubMed

    Kaabi, Mohamed Ghaith; Tonnelier, Arnaud; Martinez, Dominique

    2011-05-01

    In traditional event-driven strategies, spike timings are analytically given or calculated with arbitrary precision (up to machine precision). Exact computation is possible only for simplified neuron models, mainly the leaky integrate-and-fire model. In a recent paper, Zheng, Tonnelier, and Martinez (2009) introduced an approximate event-driven strategy, named voltage stepping, that allows the generic simulation of nonlinear spiking neurons. Promising results were achieved in the simulation of single quadratic integrate-and-fire neurons. Here, we assess the performance of voltage stepping in network simulations by considering more complex neurons (quadratic integrate-and-fire neurons with adaptation) coupled with multiple synapses. To handle the discrete nature of synaptic interactions, we recast voltage stepping in a general framework, the discrete event system specification. The efficiency of the method is assessed through simulations and comparisons with a modified time-stepping scheme of the Runge-Kutta type. We demonstrated numerically that the original order of voltage stepping is preserved when simulating connected spiking neurons, independent of the network activity and connectivity.

  5. Adapting to Reductions in Team Size: An Examination of Three Structural Alternatives

    DTIC Science & Technology

    2005-06-01

    Std Z39-18 Reductions in Team Size 2 Abstract Research on downsizing in organizations has traditionally focused on the affective- based reactions...of survivors or the reactions of financial markets to downsizing announcements. Very little research has examined how organizational units adapt to... downsizing . This paper investigates three structural approaches to downsizing in teams and directly tests the general proposition that the

  6. SHARP, a first step towards a full sized Jules Verne Launcher

    SciTech Connect

    Bertolini, L.R.; Hunter, J.W.; Powell, J.R.; Tidman, D.A.

    1993-05-01

    A vital element for space exploration and utilization is the ability to affordably place large quantities of consumables and building material into low earth orbit. Calculations and supportive data indicate this can be done with a large hydrogen gas gun referred to as the Jules Verne Launcher (JVL). We present a design for the JVL based upon the concept of side injecting preheated hydrogen along a long barrel. This dramatically reduces the peak pressures in the launcher as well as the pressures and g-loads at the vehicle. The JVL has the promise of reducing payload delivery costs to Low Earth Orbit (LEO) to below $500/kg. The Super High Altitude Research Project (SHARP) is a conventional two-stage hydrogen gas gun which is configured to launch 5 kg packages on suborbital trajectories. It is the first step towards the much larger Jules Verne system and will demonstrate several important features of the larger system. SHARP is currently in the middle of a series of tests aimed at its first milestone. This is to launch 5 kg at 4 km/sec horizontally. In its inclined configuration SHARP should launch vehicles to apogees in excess of 400 km and ranges in excess of 700 km.

  7. Body Size Adaptations to Altitudinal Climatic Variation in Neotropical Grasshoppers of the Genus Sphenarium (Orthoptera: Pyrgomorphidae)

    PubMed Central

    2015-01-01

    Altitudinal clines in body size can result from the effects of natural and sexual selection on growth rates and developing times in seasonal environments. Short growing and reproductive seasons constrain the body size that adults can attain and their reproductive success. Little is known about the effects of altitudinal climatic variation on the diversification of Neotropical insects. In central Mexico, in addition to altitude, highly heterogeneous topography generates diverse climates that can occur even at the same latitude. Altitudinal variation and heterogeneous topography open an opportunity to test the relative impact of climatic variation on body size adaptations. In this study, we investigated the relationship between altitudinal climatic variation and body size, and the divergence rates of sexual size dimorphism (SSD) in Neotropical grasshoppers of the genus Sphenarium using a phylogenetic comparative approach. In order to distinguish the relative impact of natural and sexual selection on the diversification of the group, we also tracked the altitudinal distribution of the species and trends of both body size and SSD on the phylogeny of Sphenarium. The correlative evidence suggests no relationship between altitude and body size. However, larger species were associated with places having a warmer winter season in which the temporal window for development and reproduction can be longer. Nonetheless, the largest species were also associated with highly seasonal environments. Moreover, large body size and high levels of SSD have evolved independently several times throughout the history of the group and male body size has experienced a greater evolutionary divergence than females. These lines of evidence suggest that natural selection, associated with seasonality and sexual selection, on maturation time and body size could have enhanced the diversification of this insect group. PMID:26684616

  8. Body Size Adaptations to Altitudinal Climatic Variation in Neotropical Grasshoppers of the Genus Sphenarium (Orthoptera: Pyrgomorphidae).

    PubMed

    Sanabria-Urbán, Salomón; Song, Hojun; Oyama, Ken; González-Rodríguez, Antonio; Serrano-Meneses, Martin A; Cueva Del Castillo, Raúl

    2015-01-01

    Altitudinal clines in body size can result from the effects of natural and sexual selection on growth rates and developing times in seasonal environments. Short growing and reproductive seasons constrain the body size that adults can attain and their reproductive success. Little is known about the effects of altitudinal climatic variation on the diversification of Neotropical insects. In central Mexico, in addition to altitude, highly heterogeneous topography generates diverse climates that can occur even at the same latitude. Altitudinal variation and heterogeneous topography open an opportunity to test the relative impact of climatic variation on body size adaptations. In this study, we investigated the relationship between altitudinal climatic variation and body size, and the divergence rates of sexual size dimorphism (SSD) in Neotropical grasshoppers of the genus Sphenarium using a phylogenetic comparative approach. In order to distinguish the relative impact of natural and sexual selection on the diversification of the group, we also tracked the altitudinal distribution of the species and trends of both body size and SSD on the phylogeny of Sphenarium. The correlative evidence suggests no relationship between altitude and body size. However, larger species were associated with places having a warmer winter season in which the temporal window for development and reproduction can be longer. Nonetheless, the largest species were also associated with highly seasonal environments. Moreover, large body size and high levels of SSD have evolved independently several times throughout the history of the group and male body size has experienced a greater evolutionary divergence than females. These lines of evidence suggest that natural selection, associated with seasonality and sexual selection, on maturation time and body size could have enhanced the diversification of this insect group.

  9. A Step Towards Developing Adaptive Robot-Mediated Intervention Architecture (ARIA) for Children With Autism

    PubMed Central

    Bekele, Esubalew T; Lahiri, Uttama; Swanson, Amy R.; Crittendon, Julie A.; Warren, Zachary E.; Sarkar, Nilanjan

    2013-01-01

    Emerging technology, especially robotic technology, has been shown to be appealing to children with autism spectrum disorders (ASD). Such interest may be leveraged to provide repeatable, accurate and individualized intervention services to young children with ASD based on quantitative metrics. However, existing robot-mediated systems tend to have limited adaptive capability that may impact individualization. Our current work seeks to bridge this gap by developing an adaptive and individualized robot-mediated technology for children with ASD. The system is composed of a humanoid robot with its vision augmented by a network of cameras for real-time head tracking using a distributed architecture. Based on the cues from the child’s head movement, the robot intelligently adapts itself in an individualized manner to generate prompts and reinforcements with potential to promote skills in the ASD core deficit area of early social orienting. The system was validated for feasibility, accuracy, and performance. Results from a pilot usability study involving six children with ASD and a control group of six typically developing (TD) children are presented. PMID:23221831

  10. Blood Oxygen Level-Dependent Activation of the Primary Visual Cortex Predicts Size Adaptation Illusion

    PubMed Central

    Pooresmaeili, Arezoo; Arrighi, Roberto; Biagi, Laura; Morrone, Maria Concetta

    2016-01-01

    In natural scenes, objects rarely occur in isolation but appear within a spatiotemporal context. Here, we show that the perceived size of a stimulus is significantly affected by the context of the scene: brief previous presentation of larger or smaller adapting stimuli at the same region of space changes the perceived size of a test stimulus, with larger adapting stimuli causing the test to appear smaller than veridical and vice versa. In a human fMRI study, we measured the blood oxygen level-dependent activation (BOLD) responses of the primary visual cortex (V1) to the contours of large-diameter stimuli and found that activation closely matched the perceptual rather than the retinal stimulus size: the activated area of V1 increased or decreased, depending on the size of the preceding stimulus. A model based on local inhibitory V1 mechanisms simulated the inward or outward shifts of the stimulus contours and hence the perceptual effects. Our findings suggest that area V1 is actively involved in reshaping our perception to match the short-term statistics of the visual scene. PMID:24089504

  11. Treatment of pain in patients with renal insufficiency: the World Health Organization three-step ladder adapted.

    PubMed

    Launay-Vacher, Vincent; Karie, Svetlana; Fau, Jean-Baptiste; Izzedine, Hassane; Deray, Gilbert

    2005-03-01

    The World Health Organization established official recommendations for managing pain in cancer patients. Since then, this stepladder approach has been widely adopted as a conceptual framework to treat all types of pain. However, those guidelines have not been critically evaluated for use in patients with renal insufficiency. In these patients, the questions of drug dosage adjustment and renal toxicity must be considered. This article reviews the pharmacokinetics of major analgesic drugs and data on their use and/or behavior in renal failure and considers their potential nephrotoxicity. Finally, according to available data in the international literature on pharmacokinetics, recommendations for dosage adjustment in patients with renal failure, and their potential nephrotoxicity, the World Health Organization three-step ladder for the treatment of pain was modified and adapted for patients with impaired renal function. Perspective This well-known treatment strategy now adapted for use in patients with renal insufficiency should secure and rationalize pain treatment in those patients.

  12. Head size, weaponry, and cervical adaptation: Testing craniocervical evolutionary hypotheses in Ceratopsia.

    PubMed

    VanBuren, Collin S; Campione, Nicolás E; Evans, David C

    2015-07-01

    The anterior cervical vertebrae form the skeletal connection between the cranial and postcranial skeletons in higher tetrapods. As a result, the morphology of the atlas-axis complex is likely to be shaped by selection pressures acting on either the head or neck. The neoceratopsian (Reptilia:Dinosauria) syncervical represents one of the most highly modified atlas-axis regions in vertebrates, being formed by the complete coalescence of the three most anterior cervical vertebrae. In ceratopsids, the syncervical has been hypothesized to be an adaptation to support a massive skull, or to act as a buttress during intraspecific head-to-head combat. Here, we test these functional/adaptive hypotheses within a phylogenetic framework and critically examine the previously proposed methods for quantifying relative head size in the fossil record for the first time. Results indicate that neither the evolution of cranial weaponry nor large head size correlates with the origin of cervical fusion in ceratopsians, and we, therefore, reject both adaptive hypotheses for the origin of the syncervical. Anterior cervical fusion has evolved independently in a number of amniote clades, and further research on extant groups with this peculiar anatomy is needed to understand the evolutionary basis for cervical fusion in Neoceratopsia.

  13. The Qdot-labeled actin super-resolution motility assay measures low-duty cycle muscle myosin step size.

    PubMed

    Wang, Yihua; Ajtai, Katalin; Burghardt, Thomas P

    2013-03-05

    Myosin powers contraction in heart and skeletal muscle and is a leading target for mutations implicated in inheritable muscle diseases. During contraction, myosin transduces ATP free energy into the work of muscle shortening against resisting force. Muscle shortening involves relative sliding of myosin and actin filaments. Skeletal actin filaments were fluorescently labeled with a streptavidin conjugate quantum dot (Qdot) binding biotin-phalloidin on actin. Single Qdots were imaged in time with total internal reflection fluorescence microscopy and then spatially localized to 1-3 nm using a super-resolution algorithm as they translated with actin over a surface coated with skeletal heavy meromyosin (sHMM) or full-length β-cardiac myosin (MYH7). The average Qdot-actin velocity matches measurements with rhodamine-phalloidin-labeled actin. The sHMM Qdot-actin velocity histogram contains low-velocity events corresponding to actin translation in quantized steps of ~5 nm. The MYH7 velocity histogram has quantized steps at 3 and 8 nm in addition to 5 nm and larger compliance compared to that of sHMM depending on the MYH7 surface concentration. Low-duty cycle skeletal and cardiac myosin present challenges for a single-molecule assay because actomyosin dissociates quickly and the freely moving element diffuses away. The in vitro motility assay has modestly more actomyosin interactions, and methylcellulose inhibited diffusion to sustain the complex while preserving a subset of encounters that do not overlap in time on a single actin filament. A single myosin step is isolated in time and space and then characterized using super-resolution. The approach provides a quick, quantitative, and inexpensive step size measurement for low-duty cycle muscle myosin.

  14. Numerical simulation of diffusion MRI signals using an adaptive time-stepping method

    NASA Astrophysics Data System (ADS)

    Li, Jing-Rebecca; Calhoun, Donna; Poupon, Cyril; Le Bihan, Denis

    2014-01-01

    The effect on the MRI signal of water diffusion in biological tissues in the presence of applied magnetic field gradient pulses can be modelled by a multiple compartment Bloch-Torrey partial differential equation. We present a method for the numerical solution of this equation by coupling a standard Cartesian spatial discretization with an adaptive time discretization. The time discretization is done using the explicit Runge-Kutta-Chebyshev method, which is more efficient than the forward Euler time discretization for diffusive-type problems. We use this approach to simulate the diffusion MRI signal from the extra-cylindrical compartment in a tissue model of the brain gray matter consisting of cylindrical and spherical cells and illustrate the effect of cell membrane permeability.

  15. Developing a two-step heat treatment for inactivating desiccation-adapted Salmonella spp. in aged chicken litter.

    PubMed

    Chen, Zhao; Wang, Hongye; Jiang, Xiuping

    2015-02-01

    The effectiveness of a two-step heat treatment for eliminating desiccation-adapted Salmonella spp. in aged chicken litter was evaluated. The aged chicken litter with 20, 30, 40, and 50% moisture contents was inoculated with a mixture of four Salmonella serotypes for a 24-h adaptation. Afterwards, the inoculated chicken litter was added into the chicken litter with the adjusted moisture content for a 1-h moist-heat treatment at 65 °C and 100% relative humidity inside a water bath, followed by a dry-heat treatment in a convection oven at 85 °C for 1 h to the desired moisture level (<10-12%). After moist-heat treatment, the populations of Salmonella in aged chicken litter at 20 and 30% moisture contents declined from ≈6.70 log colony-forming units (CFU)/g to 3.31 and 3.00 log CFU/g, respectively. After subsequent 1-h dry-heat treatment, the populations further decreased to 2.97 and 2.57 log CFU/g, respectively. Salmonella cells in chicken litter with 40% and 50% moisture contents were only detectable by enrichment after 40 and 20 min of moist-heat treatment, respectively. Moisture contents in all samples were reduced to <10% after a 1-h dry-heat process. Our results demonstrated that the two-step heat treatment was effective in reducing >5.5 logs of desiccation-adapted Salmonella in aged chicken litter with moisture content at or above 40%. Clearly, the findings from this study may provide the chicken litter processing industry with an effective heat treatment method for producing Salmonella-free chicken litter.

  16. Solar-driven thermo- and electrochemical degradation of nitrobenzene in wastewater: Adaptation and adoption of solar STEP concept.

    PubMed

    Gu, Di; Shao, Nan; Zhu, Yanji; Wu, Hongjun; Wang, Baohui

    2017-01-05

    The STEP concept has successfully been demonstrated for driving chemical reaction by utilization of solar heat and electricity to minimize the fossil energy, meanwhile, maximize the rate of thermo- and electrochemical reactions in thermodynamics and kinetics. This pioneering investigation experimentally exhibit that the STEP concept is adapted and adopted efficiently for degradation of nitrobenzene. By employing the theoretical calculation and thermo-dependent cyclic voltammetry, the degradation potential of nitrobenzene was found to be decreased obviously, at the same time, with greatly lifting the current, while the temperature was increased. Compared with the conventional electrochemical methods, high efficiency and fast degradation rate were markedly displayed due to the co-action of thermo- and electrochemical effects and the switch of the indirect electrochemical oxidation to the direct one for oxidation of nitrobenzene. A clear conclusion on the mechanism of nitrobenzene degradation by the STEP can be schematically proposed and discussed by the combination of thermo- and electrochemistry based the analysis of the HPLC, UV-vis and degradation data. This theory and experiment provide a pilot for the treatment of nitrobenzene wastewater with high efficiency, clean operation and low carbon footprint, without any other input of energy and chemicals from solar energy.

  17. Super-resolution reconstruction algorithm based on adaptive convolution kernel size selection

    NASA Astrophysics Data System (ADS)

    Gao, Hang; Chen, Qian; Sui, Xiubao; Zeng, Junjie; Zhao, Yao

    2016-09-01

    Restricted by the detector technology and optical diffraction limit, the spatial resolution of infrared imaging system is difficult to achieve significant improvement. Super-Resolution (SR) reconstruction algorithm is an effective way to solve this problem. Among them, the SR algorithm based on multichannel blind deconvolution (MBD) estimates the convolution kernel only by low resolution observation images, according to the appropriate regularization constraints introduced by a priori assumption, to realize the high resolution image restoration. The algorithm has been shown effective when each channel is prime. In this paper, we use the significant edges to estimate the convolution kernel and introduce an adaptive convolution kernel size selection mechanism, according to the uncertainty of the convolution kernel size in MBD processing. To reduce the interference of noise, we amend the convolution kernel in an iterative process, and finally restore a clear image. Experimental results show that the algorithm can meet the convergence requirement of the convolution kernel estimation.

  18. Closed loop adaptive control of spectrum-producing step using neural networks

    DOEpatents

    Fu, C.Y.

    1998-11-24

    Characteristics of the plasma in a plasma-based manufacturing process step are monitored directly and in real time by observing the spectrum which it produces. An artificial neural network analyzes the plasma spectrum and generates control signals to control one or more of the process input parameters in response to any deviation of the spectrum beyond a narrow range. In an embodiment, a plasma reaction chamber forms a plasma in response to input parameters such as gas flow, pressure and power. The chamber includes a window through which the electromagnetic spectrum produced by a plasma in the chamber, just above the subject surface, may be viewed. The spectrum is conducted to an optical spectrometer which measures the intensity of the incoming optical spectrum at different wavelengths. The output of optical spectrometer is provided to an analyzer which produces a plurality of error signals, each indicating whether a respective one of the input parameters to the chamber is to be increased or decreased. The microcontroller provides signals to control respective controls, but these lines are intercepted and first added to the error signals, before being provided to the controls for the chamber. The analyzer can include a neural network and an optional spectrum preprocessor to reduce background noise, as well as a comparator which compares the parameter values predicted by the neural network with a set of desired values provided by the microcontroller. 7 figs.

  19. Closed loop adaptive control of spectrum-producing step using neural networks

    DOEpatents

    Fu, Chi Yung

    1998-01-01

    Characteristics of the plasma in a plasma-based manufacturing process step are monitored directly and in real time by observing the spectrum which it produces. An artificial neural network analyzes the plasma spectrum and generates control signals to control one or more of the process input parameters in response to any deviation of the spectrum beyond a narrow range. In an embodiment, a plasma reaction chamber forms a plasma in response to input parameters such as gas flow, pressure and power. The chamber includes a window through which the electromagnetic spectrum produced by a plasma in the chamber, just above the subject surface, may be viewed. The spectrum is conducted to an optical spectrometer which measures the intensity of the incoming optical spectrum at different wavelengths. The output of optical spectrometer is provided to an analyzer which produces a plurality of error signals, each indicating whether a respective one of the input parameters to the chamber is to be increased or decreased. The microcontroller provides signals to control respective controls, but these lines are intercepted and first added to the error signals, before being provided to the controls for the chamber. The analyzer can include a neural network and an optional spectrum preprocessor to reduce background noise, as well as a comparator which compares the parameter values predicted by the neural network with a set of desired values provided by the microcontroller.

  20. A viral packaging motor varies its DNA rotation and step size to preserve subunit coordination as the capsid fills.

    PubMed

    Liu, Shixin; Chistol, Gheorghe; Hetherington, Craig L; Tafoya, Sara; Aathavan, K; Schnitzbauer, Joerg; Grimes, Shelley; Jardine, Paul J; Bustamante, Carlos

    2014-04-24

    Multimeric, ring-shaped molecular motors rely on the coordinated action of their subunits to perform crucial biological functions. During these tasks, motors often change their operation in response to regulatory signals. Here, we investigate a viral packaging machine as it fills the capsid with DNA and encounters increasing internal pressure. We find that the motor rotates the DNA during packaging and that the rotation per base pair increases with filling. This change accompanies a reduction in the motor's step size. We propose that these adjustments preserve motor coordination by allowing one subunit to make periodic, specific, and regulatory contacts with the DNA. At high filling, we also observe the downregulation of the ATP-binding rate and the emergence of long-lived pauses, suggesting a throttling-down mechanism employed by the motor near the completion of packaging. This study illustrates how a biological motor adjusts its operation in response to changing conditions, while remaining highly coordinated.

  1. The role of tissue adaptation and graft size in immune tolerance.

    PubMed

    Hauben, Ehud; Roncarolo, Maria Grazia; Draghici, Elena; Nevo, Uri

    2007-11-01

    Understanding how immune tolerance is induced and maintained is critical for our approach to immune-related diseases. Ecoimmunity is a new theory that views the immune system-tissue interaction as a co-adapting predator-prey system. Ecoimmunity suggests that tissues adapt to the selective immune pressure during ontogeny and throughout life. Therefore, immune tolerance towards 'self' represents a symmetric balance between the propensity of the immune system to prey on 'self' cells, and the tissue's specific capacity to undergo phenotypic adaptations in order to avoid destructive immune interaction. According to this theory, we hypothesized that tissues of adult immune-deficient mice, which are not exposed to selective immune pressure, will not withstand immune activity and will therefore display higher susceptibility to graft rejection. To test this prediction, C57Bl/6 wild type female mice were rendered diabetic by streptozotocin and transplanted with syngeneic pancreatic islets isolated from either immune-deficient C57Bl/6 SCID or wild type females. Remarkably, recipients of islet grafts from immune-deficient syngeneic donors displayed significantly impaired glucose homeostasis compared to mice transplanted with islets of wild type donors (p<0.001, two way repeated measures ANOVA). The severity of this impairment was correlated with islet graft size, suggesting a capacity of transplanted islets to gradually acquire a tolerogenic phenotype. These findings support the view of graft survival that is based on 'natural selection' of tissue cells. In addition, we describe a new experimental system for molecular characterization of self-tolerance.

  2. Nonlinear Effects of Nanoparticles: Biological Variability From Hormetic Doses, Small Particle Sizes, and Dynamic Adaptive Interactions

    PubMed Central

    Bell, Iris R.; Ives, John A.; Jonas, Wayne B.

    2014-01-01

    Researchers are increasingly focused on the nanoscale level of organization where biological processes take place in living systems. Nanoparticles (NPs, e.g., 1–100 nm diameter) are small forms of natural or manufactured source material whose properties differ markedly from those of the respective bulk forms of the “same” material. Certain NPs have diagnostic and therapeutic uses; some NPs exhibit low-dose toxicity; other NPs show ability to stimulate low-dose adaptive responses (hormesis). Beyond dose, size, shape, and surface charge variations of NPs evoke nonlinear responses in complex adaptive systems. NPs acquire unique size-dependent biological, chemical, thermal, optical, electromagnetic, and atom-like quantum properties. Nanoparticles exhibit high surface adsorptive capacity for other substances, enhanced bioavailability, and ability to cross otherwise impermeable cell membranes including the blood-brain barrier. With super-potent effects, nano-forms can evoke cellular stress responses or therapeutic effects not only at lower doses than their bulk forms, but also for longer periods of time. Interactions of initial effects and compensatory systemic responses can alter the impact of NPs over time. Taken together, the data suggest the need to downshift the dose-response curve of NPs from that for bulk forms in order to identify the necessarily decreased no-observed-adverse-effect-level and hormetic dose range for nanoparticles. PMID:24910581

  3. Nonlinear effects of nanoparticles: biological variability from hormetic doses, small particle sizes, and dynamic adaptive interactions.

    PubMed

    Bell, Iris R; Ives, John A; Jonas, Wayne B

    2014-05-01

    Researchers are increasingly focused on the nanoscale level of organization where biological processes take place in living systems. Nanoparticles (NPs, e.g., 1-100 nm diameter) are small forms of natural or manufactured source material whose properties differ markedly from those of the respective bulk forms of the "same" material. Certain NPs have diagnostic and therapeutic uses; some NPs exhibit low-dose toxicity; other NPs show ability to stimulate low-dose adaptive responses (hormesis). Beyond dose, size, shape, and surface charge variations of NPs evoke nonlinear responses in complex adaptive systems. NPs acquire unique size-dependent biological, chemical, thermal, optical, electromagnetic, and atom-like quantum properties. Nanoparticles exhibit high surface adsorptive capacity for other substances, enhanced bioavailability, and ability to cross otherwise impermeable cell membranes including the blood-brain barrier. With super-potent effects, nano-forms can evoke cellular stress responses or therapeutic effects not only at lower doses than their bulk forms, but also for longer periods of time. Interactions of initial effects and compensatory systemic responses can alter the impact of NPs over time. Taken together, the data suggest the need to downshift the dose-response curve of NPs from that for bulk forms in order to identify the necessarily decreased no-observed-adverse-effect-level and hormetic dose range for nanoparticles.

  4. An Efficient Adaptive Window Size Selection Method for Improving Spectrogram Visualization

    PubMed Central

    Khan, Omar Usman

    2016-01-01

    Short Time Fourier Transform (STFT) is an important technique for the time-frequency analysis of a time varying signal. The basic approach behind it involves the application of a Fast Fourier Transform (FFT) to a signal multiplied with an appropriate window function with fixed resolution. The selection of an appropriate window size is difficult when no background information about the input signal is known. In this paper, a novel empirical model is proposed that adaptively adjusts the window size for a narrow band-signal using spectrum sensing technique. For wide-band signals, where a fixed time-frequency resolution is undesirable, the approach adapts the constant Q transform (CQT). Unlike the STFT, the CQT provides a varying time-frequency resolution. This results in a high spectral resolution at low frequencies and high temporal resolution at high frequencies. In this paper, a simple but effective switching framework is provided between both STFT and CQT. The proposed method also allows for the dynamic construction of a filter bank according to user-defined parameters. This helps in reducing redundant entries in the filter bank. Results obtained from the proposed method not only improve the spectrogram visualization but also reduce the computation cost and achieves 87.71% of the appropriate window length selection. PMID:27642291

  5. An Efficient Adaptive Window Size Selection Method for Improving Spectrogram Visualization.

    PubMed

    Nisar, Shibli; Khan, Omar Usman; Tariq, Muhammad

    2016-01-01

    Short Time Fourier Transform (STFT) is an important technique for the time-frequency analysis of a time varying signal. The basic approach behind it involves the application of a Fast Fourier Transform (FFT) to a signal multiplied with an appropriate window function with fixed resolution. The selection of an appropriate window size is difficult when no background information about the input signal is known. In this paper, a novel empirical model is proposed that adaptively adjusts the window size for a narrow band-signal using spectrum sensing technique. For wide-band signals, where a fixed time-frequency resolution is undesirable, the approach adapts the constant Q transform (CQT). Unlike the STFT, the CQT provides a varying time-frequency resolution. This results in a high spectral resolution at low frequencies and high temporal resolution at high frequencies. In this paper, a simple but effective switching framework is provided between both STFT and CQT. The proposed method also allows for the dynamic construction of a filter bank according to user-defined parameters. This helps in reducing redundant entries in the filter bank. Results obtained from the proposed method not only improve the spectrogram visualization but also reduce the computation cost and achieves 87.71% of the appropriate window length selection.

  6. The PhytoSCALE project: calibrating phytoplankton cell size as a proxy for climatic adaptation

    NASA Astrophysics Data System (ADS)

    Henderiks, Jorijntje; Gerecht, Andrea; Hannisdal, Bjarte; Liow, Lee Hsiang; Reitan, Trond; Schweder, Tore; Edvardsen, Bente

    2013-04-01

    The Cenozoic fossil record reveals that coccolithophores (marine unicellular haptophyte algae) were globally more common and widespread, larger, and more heavily calcified before 34 million years ago (Ma), in a high-CO2 greenhouse world. We have recently demonstrated that changes in atmospheric CO2 have, directly or indirectly, exerted an important long-term control on the ecological prominence of coccolithophores as a whole [1]. On closer inspection, this macroevolutionary pattern primarily reflects the decline in abundance and subsequent extinction of large-celled and heavily calcified lineages, while small-sized species appear to have been more successful in adapting to the post-34 Ma "icehouse" world. Coccolith size (length) is a proxy for cellular volume-to-surface ratios (V:SA), as determined from fossil coccosphere geometries. Algal V:SA provides physiological constraints on carbon acquisition and other resource uptake rates, affecting both photosynthesis and calcification, and is therefore considered to be a key indicator of adaptation. As a general rule, small cells have faster growth rates than large cells under similar environmental conditions, giving small species a competitive advantage when resources become limiting. Our research aims to bridge the gap between short-term experimental observations of physiological and phenotypic plasticity in the modern species Emiliania huxleyi and Coccolithus pelagicus, and time series of the long-term phenotypic variability of their Cenozoic ancestors. Single-clone growth experiments revealed significant plasticity in cell size and coccolith volume under growth-limiting conditions. However, the range in coccolith size (length) remained relatively constant for single genotypes between various growth conditions. With these new data we test to what extent the size variation observed in the fossil time series is a reflection of anagenetic changes (i.e. evolution of an ancestral species to a descendant species without

  7. Influence of background size, luminance and eccentricity on different adaptation mechanisms.

    PubMed

    Gloriani, Alejandro H; Matesanz, Beatriz M; Barrionuevo, Pablo A; Arranz, Isabel; Issolio, Luis; Mar, Santiago; Aparicio, Juan A

    2016-08-01

    Mechanisms of light adaptation have been traditionally explained with reference to psychophysical experimentation. However, the neural substrata involved in those mechanisms remain to be elucidated. Our study analyzed links between psychophysical measurements and retinal physiological evidence with consideration for the phenomena of rod-cone interactions, photon noise, and spatial summation. Threshold test luminances were obtained with steady background fields at mesopic and photopic light levels (i.e., 0.06-110cd/m(2)) for retinal eccentricities from 0° to 15° using three combinations of background/test field sizes (i.e., 10°/2°, 10°/0.45°, and 1°/0.45°). A two-channel Maxwellian view optical system was employed to eliminate pupil effects on the measured thresholds. A model based on visual mechanisms that were described in the literature was optimized to fit the measured luminance thresholds in all experimental conditions. Our results can be described by a combination of visual mechanisms. We determined how spatial summation changed with eccentricity and how subtractive adaptation changed with eccentricity and background field size. According to our model, photon noise plays a significant role to explain contrast detection thresholds measured with the 1/0.45° background/test size combination at mesopic luminances and at off-axis eccentricities. In these conditions, our data reflect the presence of rod-cone interaction for eccentricities between 6° and 9° and luminances between 0.6 and 5cd/m(2). In spite of the increasing noise effects with eccentricity, results also show that the visual system tends to maintain a constant signal-to-noise ratio in the off-axis detection task over the whole mesopic range.

  8. A Bayesian adaptive blinded sample size adjustment method for risk differences.

    PubMed

    Hartley, Andrew Montgomery

    2015-01-01

    Adaptive sample size adjustment (SSA) for clinical trials consists of examining early subsets of on trial data to adjust estimates of sample size requirements. Blinded SSA is often preferred over unblinded SSA because it obviates many logistical complications of the latter and generally introduces less bias. On the other hand, current blinded SSA methods for binary data offer little to no new information about the treatment effect, ignore uncertainties associated with the population treatment proportions, and/or depend on enhanced randomization schemes that risk partial unblinding. I propose an innovative blinded SSA method for use when the primary analysis is a non-inferiority or superiority test regarding a risk difference. The method incorporates evidence about the treatment effect via the likelihood function of a mixture distribution. I compare the new method with an established one and with the fixed sample size study design, in terms of maximization of an expected utility function. The new method maximizes the expected utility better than do the comparators, under a range of assumptions. I illustrate the use of the proposed method with an example that incorporates a Bayesian hierarchical model. Lastly, I suggest topics for future study regarding the proposed methods.

  9. Widespread Genetic Incompatibilities between First-Step Mutations during Parallel Adaptation of Saccharomyces cerevisiae to a Common Environment

    PubMed Central

    Otto, Sarah P.

    2017-01-01

    Independently evolving populations may adapt to similar selection pressures via different genetic changes. The interactions between such changes, such as in a hybrid individual, can inform us about what course adaptation may follow and allow us to determine whether gene flow would be facilitated or hampered following secondary contact. We used Saccharomyces cerevisiae to measure the genetic interactions between first-step mutations that independently evolved in the same biosynthetic pathway following exposure to the fungicide nystatin. We found that genetic interactions are prevalent and predominantly negative, with the majority of mutations causing lower growth when combined in a double mutant than when alone as a single mutant (sign epistasis). The prevalence of sign epistasis is surprising given the small number of mutations tested and runs counter to expectations for mutations arising in a single biosynthetic pathway in the face of a simple selective pressure. Furthermore, in one third of pairwise interactions, the double mutant grew less well than either single mutant (reciprocal sign epistasis). The observation of reciprocal sign epistasis among these first adaptive mutations arising in the same genetic background indicates that partial postzygotic reproductive isolation could evolve rapidly between populations under similar selective pressures, even with only a single genetic change in each. The nature of the epistatic relationships was sensitive, however, to the level of drug stress in the assay conditions, as many double mutants became fitter than the single mutants at higher concentrations of nystatin. We discuss the implications of these results both for our understanding of epistatic interactions among beneficial mutations in the same biochemical pathway and for speciation. PMID:28114370

  10. First Steps School Intervention Module: CLASS-- Contingencies for Learning Academic and Social Skills. (Adapted Preschool Version). An Early School Intervention Program for At-Risk Kindergartners. A Component of the First Steps Program.

    ERIC Educational Resources Information Center

    Golly, Annemieke; Stiller, Bruce

    This report describes the second module of an early intervention program for at-risk kindergartners who show the early signs of antisocial behavior patterns. The second module of the "First Steps" program describes a school intervention involving the target child, peers, and teachers that teaches an adaptive, prosocial pattern of school…

  11. A multiobjective optimization approach for combating Aedes aegypti using chemical and biological alternated step-size control.

    PubMed

    Dias, Weverton O; Wanner, Elizabeth F; Cardoso, Rodrigo T N

    2015-11-01

    Dengue epidemics, one of the most important viral disease worldwide, can be prevented by combating the transmission vector Aedes aegypti. In support of this aim, this article proposes to analyze the Dengue vector control problem in a multiobjective optimization approach, in which the intention is to minimize both social and economic costs, using a dynamic mathematical model representing the mosquitoes' population. It consists in finding optimal alternated step-size control policies combining chemical (via application of insecticides) and biological control (via insertion of sterile males produced by irradiation). All the optimal policies consists in apply insecticides just at the beginning of the season and, then, keep the mosquitoes in an acceptable level spreading into environment a few amount of sterile males. The optimization model analysis is driven by the use of genetic algorithms. Finally, it performs a statistic test showing that the multiobjective approach is effective in achieving the same effect of variations in the cost parameters. Then, using the proposed methodology, it is possible to find, in a single run, given a decision maker, the optimal number of days and the respective amounts in which each control strategy must be applied, according to the tradeoff between using more insecticide with less transmission mosquitoes or more sterile males with more transmission mosquitoes.

  12. Exploration of zeroth-order wavefunctions and energies as a first step toward intramolecular symmetry-adapted perturbation theory

    SciTech Connect

    Gonthier, Jérôme F.; Corminboeuf, Clémence

    2014-04-21

    Non-covalent interactions occur between and within all molecules and have a profound impact on structural and electronic phenomena in chemistry, biology, and material science. Understanding the nature of inter- and intramolecular interactions is essential not only for establishing the relation between structure and properties, but also for facilitating the rational design of molecules with targeted properties. These objectives have motivated the development of theoretical schemes decomposing intermolecular interactions into physically meaningful terms. Among the various existing energy decomposition schemes, Symmetry-Adapted Perturbation Theory (SAPT) is one of the most successful as it naturally decomposes the interaction energy into physical and intuitive terms. Unfortunately, analogous approaches for intramolecular energies are theoretically highly challenging and virtually nonexistent. Here, we introduce a zeroth-order wavefunction and energy, which represent the first step toward the development of an intramolecular variant of the SAPT formalism. The proposed energy expression is based on the Chemical Hamiltonian Approach (CHA), which relies upon an asymmetric interpretation of the electronic integrals. The orbitals are optimized with a non-hermitian Fock matrix based on two variants: one using orbitals strictly localized on individual fragments and the other using canonical (delocalized) orbitals. The zeroth-order wavefunction and energy expression are validated on a series of prototypical systems. The computed intramolecular interaction energies demonstrate that our approach combining the CHA with strictly localized orbitals achieves reasonable interaction energies and basis set dependence in addition to producing intuitive energy trends. Our zeroth-order wavefunction is the primary step fundamental to the derivation of any perturbation theory correction, which has the potential to truly transform our understanding and quantification of non

  13. Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey.

    PubMed

    Marchis, F; Kaasalainen, M; Hom, E F Y; Berthier, J; Enriquez, J; Hestroffer, D; Le Mignant, D; de Pater, I

    2006-11-01

    This paper presents results from a high spatial resolution survey of 33 main-belt asteroids with diameters >40 km using the Keck II Adaptive Optics (AO) facility. Five of these (45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra) were confirmed to have satellite. Assuming the same albedo as the primary, these moonlets are relatively small (∼5% of the primary size) suggesting that they are fragments captured after a disruptive collision of a parent body or captured ejecta due to an impact. For each asteroid, we have estimated the minimum size of a moonlet that can positively detected within the Hill sphere of the system by estimating and modeling a 2-σ detection profile: in average on the data set, a moonlet located at 2/100 × R(Hill) (1/4 × R(Hill)) with a diameter larger than 6 km (4 km) would have been unambiguously seen. The apparent size and shape of each asteroid was estimated after deconvolution using a new algorithm called AIDA. The mean diameter for the majority of asteroids is in good agreement with IRAS radiometric measurements, though for asteroids with a D < 200 km, it is underestimated on average by 6-8%. Most asteroids had a size ratio that was very close to those determined by lightcurve measurements. One observation of 104 Klymene suggests it has a bifurcated shape. The bi-lobed shape of 121 Hermione described in Marchis et al. [Marchis, F., Hestroffer, D., Descamps, P., Berthier, J., Laver, C., de Pater, I., 2005c. Icarus 178, 450-464] was confirmed after deconvolution. The ratio of contact binaries in our survey, which is limited to asteroids larger than 40 km, is surprisingly high (∼6%), suggesting that a non-single configuration is common in the main-belt. Several asteroids have been analyzed with lightcurve inversions. We compared lightcurve inversion models for plane-of-sky predictions with the observed images (9 Metis, 52 Europa, 87 Sylvia, 130 Elektra, 192 Nausikaa, and 423 Diotima, 511 Davida). The AO images allowed us to

  14. Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey

    PubMed Central

    Marchis, F.; Kaasalainen, M.; Hom, E.F.Y.; Berthier, J.; Enriquez, J.; Hestroffer, D.; Le Mignant, D.; de Pater, I.

    2008-01-01

    This paper presents results from a high spatial resolution survey of 33 main-belt asteroids with diameters >40 km using the Keck II Adaptive Optics (AO) facility. Five of these (45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra) were confirmed to have satellite. Assuming the same albedo as the primary, these moonlets are relatively small (∼5% of the primary size) suggesting that they are fragments captured after a disruptive collision of a parent body or captured ejecta due to an impact. For each asteroid, we have estimated the minimum size of a moonlet that can positively detected within the Hill sphere of the system by estimating and modeling a 2-σ detection profile: in average on the data set, a moonlet located at 2/100 × RHill (1/4 × RHill) with a diameter larger than 6 km (4 km) would have been unambiguously seen. The apparent size and shape of each asteroid was estimated after deconvolution using a new algorithm called AIDA. The mean diameter for the majority of asteroids is in good agreement with IRAS radiometric measurements, though for asteroids with a D < 200 km, it is underestimated on average by 6–8%. Most asteroids had a size ratio that was very close to those determined by lightcurve measurements. One observation of 104 Klymene suggests it has a bifurcated shape. The bi-lobed shape of 121 Hermione described in Marchis et al. [Marchis, F., Hestroffer, D., Descamps, P., Berthier, J., Laver, C., de Pater, I., 2005c. Icarus 178, 450–464] was confirmed after deconvolution. The ratio of contact binaries in our survey, which is limited to asteroids larger than 40 km, is surprisingly high (∼6%), suggesting that a non-single configuration is common in the main-belt. Several asteroids have been analyzed with lightcurve inversions. We compared lightcurve inversion models for plane-of-sky predictions with the observed images (9 Metis, 52 Europa, 87 Sylvia, 130 Elektra, 192 Nausikaa, and 423 Diotima, 511 Davida). The AO images allowed us to

  15. Body size and testicular traits of tropically-adapted bucks raised under extensive husbandry in Ethiopia.

    PubMed

    Mekasha, Y; Tegegne, A; Abera, A; Rodriguez-Martinez, H

    2008-04-01

    Five tropically adapted buck breeds extensively managed in Ethiopia were studied to determine possible effects of breed and age on body size and testicular traits. In all, 177 bucks were selected following stratified random sampling, and evaluated in three age groups: <14 months (young), 14-19.5 months (intermediate) and 19.6-24 months (old). The breeds studied were Arsi-Bale (AB; N = 35), Central Highlands (CH; N = 33), Afar (N = 35), Boran (N = 36) and Woito-Guji (WG; N = 38). In all the three age groups, Boran and CH bucks were the heaviest (p < 0.05), Afar were the lightest, and AB and WG were in between. The highest body weight (BW) was achieved in the intermediate age group for Afar, but in the oldest age group for the other breeds. In the youngest age group, scrotal circumference (SC) was the widest (p < 0.05) for Boran and CH and the narrowest for Afar, AB and WG, while in the intermediate and the oldest age groups, Boran showed the widest SC. Boran, WG and CH had higher (p < 0.05) testicular weight (TW) than Afar and AB in the youngest age group. Boran retained the highest (p < 0.05) TW in the intermediate and the oldest age groups, while in the oldest age group WG and AB medium TW and Afar had the lowest TW. However, Afar had the highest TW expressed as percentage of BW. SC was well correlated with TW (p < 0.001; r = 0.74) and BW (p < 0.001; r = 0.61), indicating a linear, positive association between BW and TW (p < 0.001; r = 0.51). In conclusion, body size and testicular traits of Ethiopian bucks under an extensive management system are influenced differently by breed and age group.

  16. Combined use of leaf size and economics traits allows direct comparison of hydrophyte and terrestrial herbaceous adaptive strategies

    PubMed Central

    Pierce, Simon; Brusa, Guido; Sartori, Matteo; Cerabolini, Bruno E. L.

    2012-01-01

    Background and Aims Hydrophytes generally exhibit highly acquisitive leaf economics. However, a range of growth forms is evident, from small, free-floating and rapidly growing Lemniden to large, broad-leaved Nymphaeiden, denoting variability in adaptive strategies. Traits used to classify adaptive strategies in terrestrial species, such as canopy height, are not applicable to hydrophytes. We hypothesize that hydrophyte leaf size traits and economics exhibit sufficient overlap with terrestrial species to allow a common classification of plant functional types, sensu Grime's CSR theory. Methods Leaf morpho-functional traits were measured for 61 species from 47 water bodies in lowland continental, sub-alpine and alpine bioclimatic zones in southern Europe and compared against the full leaf economics spectrum and leaf size range of terrestrial herbs, and between hydrophyte growth forms. Key Results Hydrophytes differed in the ranges and mean values of traits compared with herbs, but principal components analysis (PCA) demonstrated that both groups shared axes of trait variability: PCA1 encompassed size variation (area and mass), and PCA2 ranged from relatively dense, carbon-rich leaves to nitrogen-rich leaves of high specific leaf area (SLA). Most growth forms exhibited trait syndromes directly equivalent to herbs classified as R adapted, although Nymphaeiden ranged between C and SR adaptation. Conclusions Our findings support the hypothesis that hydrophyte adaptive strategy variation reflects fundamental trade-offs in economics and size that govern all plants, and that hydrophyte adaptive strategies can be directly compared with terrestrial species by combining leaf economics and size traits. PMID:22337079

  17. The critical size is set at a single-cell level by growth rate to attain homeostasis and adaptation.

    PubMed

    Ferrezuelo, Francisco; Colomina, Neus; Palmisano, Alida; Garí, Eloi; Gallego, Carme; Csikász-Nagy, Attila; Aldea, Martí

    2012-01-01

    Budding yeast cells are assumed to trigger Start and enter the cell cycle only after they attain a critical size set by external conditions. However, arguing against deterministic models of cell size control, cell volume at Start displays great individual variability even under constant conditions. Here we show that cell size at Start is robustly set at a single-cell level by the volume growth rate in G1, which explains the observed variability. We find that this growth-rate-dependent sizer is intimately hardwired into the Start network and the Ydj1 chaperone is key for setting cell size as a function of the individual growth rate. Mathematical modelling and experimental data indicate that a growth-rate-dependent sizer is sufficient to ensure size homeostasis and, as a remarkable advantage over a rigid sizer mechanism, it reduces noise in G1 length and provides an immediate solution for size adaptation to external conditions at a population level.

  18. Mechanisms of adaptation from a multiple to a single step recovery strategy following repeated exposure to forward loss of balance in older adults.

    PubMed

    Carty, Christopher P; Cronin, Neil J; Lichtwark, Glen A; Mills, Peter M; Barrett, Rod S

    2012-01-01

    When released from an initial, static, forward lean angle and instructed to recover with a single step, some older adults are able to meet the task requirements, whereas others either stumble or fall. The purpose of the present study was to use the concept of margin of stability (MoS) to investigate balance recovery responses in the anterior-posterior direction exhibited by older single steppers, multiple steppers and those that are able to adapt from multiple to single steps following exposure to repeated forward loss of balance. One hundred and fifty-one healthy, community dwelling, older adults, aged 65-80 years, participated in the study. Participants performed four trials of the balance recovery task from each of three initial lean angles. Balance recovery responses in the anterior-posterior direction were quantified at three events; cable release (CR), toe-off (TO) and foot contact (FC), for trials performed at the intermediate lean angle. MoS was computed as the anterior-posterior distance between the forward boundary of the Base of Support (BoS) and the vertical projection of the velocity adjusted centre of mass position (XCoM). Approximately one-third of participants adapted from a multiple to a single step recovery strategy following repeated exposure to the task. MoS at FC for the single and multiple step trials in the adaptation group were intermediate between the exclusively single step group and the exclusively multiple step group, with the single step trials having a significant, 3.7 times higher MoS at FC than the multiple step trials. Consistent with differences between single and multiple steppers, adaptation from multiple to single steps was attributed to an increased BoS at FC, a reduced XCoM at FC and an increased rate of BoS displacement from TO to FC. Adaptations occurred within a single test session and suggest older adults that are close to the threshold of successful recovery can rapidly improve dynamic stability following repeated

  19. Polytomous Adaptive Classification Testing: Effects of Item Pool Size, Test Termination Criterion, and Number of Cutscores

    ERIC Educational Resources Information Center

    Gnambs, Timo; Batinic, Bernad

    2011-01-01

    Computer-adaptive classification tests focus on classifying respondents in different proficiency groups (e.g., for pass/fail decisions). To date, adaptive classification testing has been dominated by research on dichotomous response formats and classifications in two groups. This article extends this line of research to polytomous classification…

  20. Long-Lasting Modifications of Saccadic Eye Movements Following Adaptation Induced in the Double-Step Target Paradigm

    ERIC Educational Resources Information Center

    Alahyane, Nadia; Pelisson, Denis

    2005-01-01

    The adaptation of saccadic eye movements to environmental changes occurring throughout life is a good model of motor learning and motor memory. Numerous studies have analyzed the behavioral properties and neural substrate of oculomotor learning in short-term saccadic adaptation protocols, but to our knowledge, none have tested the persistence of…

  1. Adaptation of an evidence-based intervention for Appalachian women: new STEPS (Strength Through Education, Physical fitness and Support) for breast health.

    PubMed

    Gallant, Nancy R; Corbin, Marilyn; Bencivenga, Marcyann M; Farnan, Michelle; Wiker, Nancy; Bressler, Andrea; Camacho, Fabian; Lengerich, Eugene J

    2013-06-01

    Appalachia is characterized by a high prevalence of individual-level risks for breast cancer, including physical inactivity and postmenopausal obesity. The availability of local, evidence-based programs to improve physical fitness is limited. We adapted an evidence-based intervention, StrongWomen, to improve physical fitness and increase breast cancer knowledge among women 40 years and older in Appalachian Pennsylvania. Utilizing a multi-site, community-based design, we tested the adapted 12-week, supervised program-New STEPS (Strength Through Education, Physical fitness and Support)-among 139 women. The completion rate was 67.6 %. Pre/post scores improved for each of six fitness assessments (P<0.01). We found differences in overall fitness by study site (P<0.001), but no differences by age (P=0.13) or by previous breast cancer diagnosis (P=0.73). New STEPS is an adapted, evidence-based program that can improve physical fitness and breast cancer awareness among women in Appalachian Pennsylvania. New STEPS may help fill a void in local fitness programs for Appalachian women at risk for breast cancer or breast cancer recurrence.

  2. Geographic body size variation in the periodical cicadas Magicicada: implications for life cycle divergence and local adaptation.

    PubMed

    Koyama, T; Ito, H; Kakishima, S; Yoshimura, J; Cooley, J R; Simon, C; Sota, T

    2015-06-01

    Seven species in three species groups (Decim, Cassini and Decula) of periodical cicadas (Magicicada) occupy a wide latitudinal range in the eastern United States. To clarify how adult body size, a key trait affecting fitness, varies geographically with climate conditions and life cycle, we analysed the relationships of population mean head width to geographic variables (latitude, longitude, altitude), habitat annual mean temperature (AMT), life cycle and species differences. Within species, body size was larger in females than males and decreased with increasing latitude (and decreasing habitat AMT), following the converse Bergmann's rule. For the pair of recently diverged 13- and 17-year species in each group, 13-year cicadas were equal in size or slightly smaller on average than their 17-year counterparts despite their shorter developmental time. This fact suggests that, under the same climatic conditions, 17-year cicadas have lowered growth rates compared to their 13-years counterparts, allowing 13-year cicadas with faster growth rates to achieve body sizes equivalent to those of their 17-year counterparts at the same locations. However, in the Decim group, which includes two 13-year species, the more southerly, anciently diverged 13-year species (Magicicada tredecim) was characterized by a larger body size than the other, more northerly 13- and 17-year species, suggesting that local adaptation in warmer habitats may ultimately lead to evolution of larger body sizes. Our results demonstrate how geographic clines in body size may be maintained in sister species possessing different life cycles.

  3. Two-step size reduction and post-washing of steam exploded corn stover improving simultaneous saccharification and fermentation for ethanol production.

    PubMed

    Liu, Zhi-Hua; Chen, Hong-Zhang

    2017-01-01

    The simultaneous saccharification and fermentation (SSF) of corn stover biomass for ethanol production was performed by integrating steam explosion (SE) pretreatment, hydrolysis and fermentation. Higher SE pretreatment severity and two-step size reduction increased the specific surface area, swollen volume and water holding capacity of steam exploded corn stover (SECS) and hence facilitated the efficiency of hydrolysis and fermentation. The ethanol production and yield in SSF increased with the decrease of particle size and post-washing of SECS prior to fermentation to remove the inhibitors. Under the SE conditions of 1.5MPa and 9min using 2.0cm particle size, glucan recovery and conversion to glucose by enzymes were 86.2% and 87.2%, respectively. The ethanol concentration and yield were 45.0g/L and 85.6%, respectively. With this two-step size reduction and post-washing strategy, the water utilization efficiency, sugar recovery and conversion, and ethanol concentration and yield by the SSF process were improved.

  4. Statistical modelling of wildfire size and intensity: a step toward meteorological forecasting of summer extreme fire risk

    NASA Astrophysics Data System (ADS)

    Hernandez, C.; Keribin, C.; Drobinski, P.; Turquety, S.

    2015-12-01

    In this article we investigate the use of statistical methods for wildfire risk assessment in the Mediterranean Basin using three meteorological covariates, the 2 m temperature anomaly, the 10 m wind speed and the January-June rainfall occurrence anomaly. We focus on two remotely sensed characteristic fire variables, the burnt area (BA) and the fire radiative power (FRP), which are good proxies for fire size and intensity respectively. Using the fire data we determine an adequate parametric distribution function which fits best the logarithm of BA and FRP. We reconstruct the conditional density function of both variables with respect to the chosen meteorological covariates. These conditional density functions for the size and intensity of a single event give information on fire risk and can be used for the estimation of conditional probabilities of exceeding certain thresholds. By analysing these probabilities we find two fire risk regimes different from each other at the 90 % confidence level: a "background" summer fire risk regime and an "extreme" additional fire risk regime, which corresponds to higher probability of occurrence of larger fire size or intensity associated with specific weather conditions. Such a statistical approach may be the ground for a future fire risk alert system.

  5. Adaptation.

    PubMed

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

  6. Social Influences on Executive Functions Development in Children and Adolescents: Steps Toward a Social Neuroscience of Predictive Adaptive Responses.

    PubMed

    Dishion, Thomas J

    2016-01-01

    This commentary discusses the findings and implications of four empirical papers that establish a reciprocal, longitudinal link between the social environment and executive functions from childhood to adolescence. Two future directions are suggested by this work. The first is a call for measurement research to clarify the nomological network of various measurements of self-regulation and executive functions across a variety of methods and procedures. The second new direction is to broaden the analysis of executive function to include a wider array of predictive adaptive responses to various environmental conditions, including those where youth are chronically marginalized or otherwise stressed. Findings from these studies suggest that the executive functions within the brain guide adaptation in both deviant as well as competent responses to the social environment. Understanding various forms of adaptation will enhance the potential for prevention as well as avoid iatrogenic intervention strategies with misinformed targets.

  7. Adaptive sample size modification in clinical trials: start small then ask for more?

    PubMed

    Jennison, Christopher; Turnbull, Bruce W

    2015-12-20

    We consider sample size re-estimation in a clinical trial, in particular when there is a significant delay before the measurement of patient response. Mehta and Pocock have proposed methods in which sample size is increased when interim results fall in a 'promising zone' where it is deemed worthwhile to increase conditional power by adding more subjects. Our analysis reveals potential pitfalls in applying this approach. Mehta and Pocock use results of Chen, DeMets and Lan to identify when increasing sample size, but applying a conventional level α significance test at the end of the trial does not inflate the type I error rate: we have found the greatest gains in power per additional observation are liable to lie outside the region defined by this method. Mehta and Pocock increase sample size to achieve a particular conditional power, calculated under the current estimate of treatment effect: this leads to high increases in sample size for a small range of interim outcomes, whereas we have found it more efficient to make moderate increases in sample size over a wider range of cases. If the aforementioned pitfalls are avoided, we believe the broad framework proposed by Mehta and Pocock is valuable for clinical trial design. Working in this framework, we propose sample size rules that apply explicitly the principle of adding observations when they are most beneficial. The resulting trial designs are closely related to efficient group sequential tests for a delayed response proposed by Hampson and Jennison.

  8. Estimated performance of an adaptive trailing-edge device aimed at reducing fuel consumption on a medium-size aircraft

    NASA Astrophysics Data System (ADS)

    Diodati, Gianluca; Concilio, Antonio; Ricci, Sergio; De Gaspari, Alessandro; Huvelin, Fabien; Dumont, Antoine; Godard, Jean-Luc

    2013-03-01

    This paper deals with the estimation of the performance of a medium-size aircraft (3-hour flight range) equipped with an adaptive trailing edge device (ATED) that runs span-wise from the wing root in the flap zone and extends chord-wise for a limited percentage of the MAC. Computations are calculated referring to the full wing and do not refer to the complete aircraft configuration. Aerodynamic computations, taking into account ideal shapes, have been performed by using both Euler and Navier- Stokes method in order to extract the wing polars for the reference and the optimal wing, implementing an ATED, deflected upwards and downwards. A comparison of the achieved results is discussed. Considering the shape domain, a suitable interpolation procedure has been set up to obtain the wing polar envelop of the adaptive wing, intended as the set of "best" values, picked by each different polar. At the end, the performances of the complete reference and adaptive wing are computed and compared for a symmetric, centered, leveled and steady cruise flight for a medium size aircraft. A significant fuel burn reduction estimate or, alternatively, an increased range capability is demonstrated, with margins of further improvements. The research leading to these results has gratefully received funding from the European Union Seventh Framework Programme (FP7/2007- 2013) under Grant Agreement n° 284562.

  9. The Chinese Life-Steps Program: A Cultural Adaptation of a Cognitive-Behavioral Intervention to Enhance HIV Medication Adherence

    ERIC Educational Resources Information Center

    Shiu, Cheng-Shi; Chen, Wei-Ti; Simoni, Jane; Fredriksen-Goldsen, Karen; Zhang, Fujie; Zhou, Hongxin

    2013-01-01

    China is considered to be the new frontier of the global AIDS pandemic. Although effective treatment for HIV is becoming widely available in China, adherence to treatment remains a challenge. This study aimed to adapt an intervention promoting HIV-medication adherence--favorably evaluated in the West--for Chinese HIV-positive patients. The…

  10. Steps Ahead: Adaptation of physical activity and dietary guidelines for reducing unhealthy weight gain in the Lower Misissippi Delta

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of our study was to test the effectiveness of adapting the Dietary Guidelines for Americans (2010) (DG), with and without a physical activity (PA) component, in reducing weight gain in the Lower Mississippi Delta region (LMD) of the United States. A sample of 121 White and African-Americ...

  11. Saccade Adaptation and Visual Uncertainty

    PubMed Central

    Souto, David; Gegenfurtner, Karl R.; Schütz, Alexander C.

    2016-01-01

    Visual uncertainty may affect saccade adaptation in two complementary ways. First, an ideal adaptor should take into account the reliability of visual information for determining the amount of correction, predicting that increasing visual uncertainty should decrease adaptation rates. We tested this by comparing observers' direction discrimination and adaptation rates in an intra-saccadic-step paradigm. Second, clearly visible target steps may generate a slower adaptation rate since the error can be attributed to an external cause, instead of an internal change in the visuo-motor mapping that needs to be compensated. We tested this prediction by measuring saccade adaptation to different step sizes. Most remarkably, we found little correlation between estimates of visual uncertainty and adaptation rates and no slower adaptation rates with more visible step sizes. Additionally, we show that for low contrast targets backward steps are perceived as stationary after the saccade, but that adaptation rates are independent of contrast. We suggest that the saccadic system uses different position signals for adapting dysmetric saccades and for generating a trans-saccadic stable visual percept, explaining that saccade adaptation is found to be independent of visual uncertainty. PMID:27252635

  12. Coevolution of adaptive technology, maladaptive culture and population size in a producer-scrounger game.

    PubMed

    Lehmann, Laurent; Feldman, Marcus W

    2009-11-07

    Technology (i.e. tools, methods of cultivation and domestication, systems of construction and appropriation, machines) has increased the vital rates of humans, and is one of the defining features of the transition from Malthusian ecological stagnation to a potentially perpetual rising population growth. Maladaptations, on the other hand, encompass behaviours, customs and practices that decrease the vital rates of individuals. Technology and maladaptations are part of the total stock of culture carried by the individuals in a population. Here, we develop a quantitative model for the coevolution of cumulative adaptive technology and maladaptive culture in a 'producer-scrounger' game, which can also usefully be interpreted as an 'individual-social' learner interaction. Producers (individual learners) are assumed to invent new adaptations and maladaptations by trial-and-error learning, insight or deduction, and they pay the cost of innovation. Scroungers (social learners) are assumed to copy or imitate (cultural transmission) both the adaptations and maladaptations generated by producers. We show that the coevolutionary dynamics of producers and scroungers in the presence of cultural transmission can have a variety of effects on population carrying capacity. From stable polymorphism, where scroungers bring an advantage to the population (increase in carrying capacity), to periodic cycling, where scroungers decrease carrying capacity, we find that selection-driven cultural innovation and transmission may send a population on the path of indefinite growth or to extinction.

  13. Peak Muscle Activation, Joint Kinematics, and Kinetics during Elliptical and Stepping Movement Pattern on a Precor Adaptive Motion Trainer

    ERIC Educational Resources Information Center

    Rogatzki, Matthew J.; Kernozek, Thomas W.; Willson, John D.; Greany, John F.; Hong, Di-An; Porcari, John P.

    2012-01-01

    Kinematic, kinetic, and electromyography data were collected from the biceps femoris, rectus femoris (RF), gluteus maximus, and erector spinae (ES) during a step and elliptical exercise at a standardized workload with no hand use. Findings depicted 95% greater ankle plantar flexion (p = 0.01), 29% more knee extension (p = 0.003), 101% higher peak…

  14. The adaptive significance of population differentiation in offspring size of the least killifish, Heterandria formosa

    PubMed Central

    Leips, Jeff; Helen Rodd, F; Travis, Joseph

    2013-01-01

    We tested the hypothesis that density-dependent competition influences the evolution of offspring size. We studied two populations of the least killifish (Heterandria formosa) that differ dramatically in population density; these populations are genetically differentiated for offspring size, and females from both populations produce larger offspring when they experience higher social densities. To look at the influences of population of origin and relative body size on competitive ability, we held females from the high-density population at two different densities to create large and small offspring with the same genetic background. We measured the competitive ability of those offspring in mesocosms that contained either pure or mixed population treatments at either high or low density. High density increased competition, which was most evident in greatly reduced individual growth rates. Larger offspring from the high-density population significantly delayed the onset of maturity of fish from the low-density population. From our results, we infer that competitive conditions in nature have contributed to the evolution of genetically based interpopulation differences in offspring size as well as plasticity in offspring size in response to conspecific density. PMID:23610636

  15. Endopolyploidy as a potential alternative adaptive strategy for Arabidopsis leaf size variation in response to UV-B.

    PubMed

    Gegas, Vasilis C; Wargent, Jason J; Pesquet, Edouard; Granqvist, Emma; Paul, Nigel D; Doonan, John H

    2014-06-01

    The extent of endoreduplication in leaf growth is group- or even species-specific, and its adaptive role is still unclear. A survey of Arabidopsis accessions for variation at the level of endopolyploidy, cell number, and cell size in leaves revealed extensive genetic variation in endopolyploidy level. High endopolyploidy is associated with increased leaf size, both in natural and in genetically unstructured (mapping) populations. The underlying genes were identified as quantitative trait loci that control endopolyploidy in nature by modulating the progression of successive endocycles during organ development. This complex genetic architecture indicates an adaptive mechanism that allows differential organ growth over a broad geographic range and under stressful environmental conditions. UV-B radiation was identified as a significant positive climatic predictor for high endopolyploidy. Arabidopsis accessions carrying the increasing alleles for endopolyploidy also have enhanced tolerance to UV-B radiation. UV-absorbing secondary metabolites provide an additional protective strategy in accessions that display low endopolyploidy. Taken together, these results demonstrate that high constitutive endopolyploidy is a significant predictor for organ size in natural populations and is likely to contribute to sustaining plant growth under high incident UV radiation. Endopolyploidy may therefore form part of the range of UV-B tolerance mechanisms that exist in natural populations.

  16. Parametric study of grid size, time step and turbulence modeling on Navier-Stokes computations over airfoils

    NASA Technical Reports Server (NTRS)

    Rumsey, Christopher L.; Anderson, W. Kyle

    1988-01-01

    An upwind-biased implicit approximate factorization algorithm is applied to several steady and unsteady turbulent flows. The thin layer form of the compressible Navier-Stokes equation is used. Both the flux vector splitting and flux difference splitting methods are used to determine fluxes, and the results are compared. Flux difference splitting predicts results more accurately than flux vector splitting on a given mesh size, but, in its present implementation, is more severely limited by the maximum CFL number for unsteady time accurate flows. Physical aspects of the computations are also examined. An equilibrium turbulent boundary layer model computes generally better steady and unsteady results than a nonequilibrium model when there is little to no boundary layer separation. Conversely, when a significant region of separation exists, the nonequilibrium model performs in better agreement with experiment.

  17. Two-Step Nucleation and Growth of InP Quantum Dots via Magic-Sized Cluster Intermediates

    SciTech Connect

    Gary, Dylan C.; Terban, Maxwell W.; Billinge, Simon J. L.; Cossairt, Brandi M.

    2015-01-30

    We report on the role of magic-sized clusters (MSCs) as key intermediates in the synthesis of indium phosphide quantum dots (InP QDs) from molecular precursors. These observations suggest that previous efforts to control nucleation and growth by tuning precursor reactivity have been undermined by formation of these kinetically persistent MSCs prior to QD formation. The thermal stability of InP MSCs is influenced by the presence of exogenous bases as well as choice of the anionic ligand set. Addition of a primary amine, a common additive in previous InP QD syntheses, to carboxylate terminated MSCs was found to bypass the formation of MSCs, allowing for homogeneous growth of InP QDs through a continuum of isolable sizes. Substitution of the carboxylate ligand set for a phosphonate ligand set increased the thermal stability of one particular InP MSC to 400°C. The structure and optical properties of the MSCs with both carboxylate and phosphonate ligand sets were studied by UV-Vis absorption spectroscopy, powder XRD analysis, and solution ³¹P{¹H} and ¹H NMR spectroscopy. Finally, the carboxylate terminated MSCs were identified as effective single source precursors (SSPs) for the synthesis of high quality InP QDs. Employing InP MSCs as SSPs for QDs effectively decouples the formation of MSCs from the subsequent second nucleation event and growth of InP QDs. The concentration dependence of this SSP reaction, as well as the shape uniformity of particles observed by TEM suggests that the stepwise growth from MSCs directly to QDs proceeds via a second nucleation event rather than an aggregative growth mechanism.

  18. Two-Step Nucleation and Growth of InP Quantum Dots via Magic-Sized Cluster Intermediates

    DOE PAGES

    Gary, Dylan C.; Terban, Maxwell W.; Billinge, Simon J. L.; ...

    2015-01-30

    We report on the role of magic-sized clusters (MSCs) as key intermediates in the synthesis of indium phosphide quantum dots (InP QDs) from molecular precursors. These observations suggest that previous efforts to control nucleation and growth by tuning precursor reactivity have been undermined by formation of these kinetically persistent MSCs prior to QD formation. The thermal stability of InP MSCs is influenced by the presence of exogenous bases as well as choice of the anionic ligand set. Addition of a primary amine, a common additive in previous InP QD syntheses, to carboxylate terminated MSCs was found to bypass the formationmore » of MSCs, allowing for homogeneous growth of InP QDs through a continuum of isolable sizes. Substitution of the carboxylate ligand set for a phosphonate ligand set increased the thermal stability of one particular InP MSC to 400°C. The structure and optical properties of the MSCs with both carboxylate and phosphonate ligand sets were studied by UV-Vis absorption spectroscopy, powder XRD analysis, and solution ³¹P{¹H} and ¹H NMR spectroscopy. Finally, the carboxylate terminated MSCs were identified as effective single source precursors (SSPs) for the synthesis of high quality InP QDs. Employing InP MSCs as SSPs for QDs effectively decouples the formation of MSCs from the subsequent second nucleation event and growth of InP QDs. The concentration dependence of this SSP reaction, as well as the shape uniformity of particles observed by TEM suggests that the stepwise growth from MSCs directly to QDs proceeds via a second nucleation event rather than an aggregative growth mechanism.« less

  19. First steps toward 3D high resolution imaging using adaptive optics and full-field optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Blanco, Leonardo; Blavier, Marie; Glanc, Marie; Pouplard, Florence; Tick, Sarah; Maksimovic, Ivan; Chenegros, Guillaume; Mugnier, Laurent; Lacombe, Francois; Rousset, Gérard; Paques, Michel; Le Gargasson, Jean-François; Sahel, Jose-Alain

    2008-09-01

    We describe here two parts of our future 3D fundus camera coupling Adaptive Optics and full-field Optical Coherence Tomography. The first part is an Adaptive Optics flood imager installed at the Quinze-Vingts Hospital, regularly used on healthy and pathological eyes. A posteriori image reconstruction is performed, increasing the final image quality and field of view. The instrument lateral resolution is better than 2 microns. The second part is a full-field Optical Coherence Tomograph, which has demonstrated capability of performing a simple kind of "4 phases" image reconstruction of non biological samples and ex situ retinas. Final aim is to couple both parts in order to achieve 3D high resolution mapping of in vivo retinas.

  20. Size as a line of least evolutionary resistance: diet and adaptive morphological radiation in New World monkeys.

    PubMed

    Marroig, Gabriel; Cheverud, James M

    2005-05-01

    New World monkeys (NWM) display substantial variation (two orders of magnitude) in body size. Despite this, variation in skull size and associated shape show a conserved allometric relationship, both within and between genera. Maximum likelihood estimates of quantitative ancestral states were used to compare the direction of morphological differentiation with the phenotypic (p(max)) and genetic (g(max)) lines of least evolutionary resistance (LLER). Diversification in NWM skulls occurred principally along the LLER defined by size variation. We also obtained measures of morphological amount and pace of change using our skull data together with published genetic distances to test whether the LLER influenced the amount and pace of diversification. Moreover, data on an ecological factor (diet) was obtained from the literature and used to test the association of this niche-related measure with the morphological diversification. Two strategies were used to test the association of LLER with the morphological and dietary amount and pace of change, one focusing on both contemporary genera and maximum likelihood reconstructed ancestors and the other using only the 16 contemporary genera in a phylogenetic comparative analysis. Our results suggest that the LLER influenced the path, amount, and pace of morphological change. Evolution also occurred away from the LLER in some taxa but this occurred at a slower pace and resulted in a relatively low amount of morphological change. We found that longer branch lengths (time) are associated with larger differences in p(max) orientation. However, on a macroevolutionary scale there is no such trend. Diet is consistently associated with both absolute size differences and morphological integration patterns, and we suggest that this ecological factor might be driving adaptive radiation in NWM. Invasion of diet-based adaptive zones involves changes in absolute size, due to metabolic and foraging constraints, resulting in simple allometric

  1. High order finite volume methods on wavelet-adapted grids with local time-stepping on multicore architectures for the simulation of shock-bubble interactions

    NASA Astrophysics Data System (ADS)

    Hejazialhosseini, Babak; Rossinelli, Diego; Bergdorf, Michael; Koumoutsakos, Petros

    2010-11-01

    We present a space-time adaptive solver for single- and multi-phase compressible flows that couples average interpolating wavelets with high-order finite volume schemes. The solver introduces the concept of wavelet blocks, handles large jumps in resolution and employs local time-stepping for efficient time integration. We demonstrate that the inherently sequential wavelet-based adaptivity can be implemented efficiently in multicore computer architectures using task-based parallelism and introducing the concept of wavelet blocks. We validate our computational method on a number of benchmark problems and we present simulations of shock-bubble interaction at different Mach numbers, demonstrating the accuracy and computational performance of the method.

  2. Adaptations to "Thermal Time" Constraints in Papilio: Latitudinal and Local Size Clines Differ in Response to Regional Climate Change.

    PubMed

    Scriber, J Mark; Elliot, Ben; Maher, Emily; McGuire, Molly; Niblack, Marjie

    2014-01-21

    Adaptations to "thermal time" (=Degree-day) constraints on developmental rates and voltinism for North American tiger swallowtail butterflies involve most life stages, and at higher latitudes include: smaller pupae/adults; larger eggs; oviposition on most nutritious larval host plants; earlier spring adult emergences; faster larval growth and shorter molting durations at lower temperatures. Here we report on forewing sizes through 30 years for both the northern univoltine P. canadensis (with obligate diapause) from the Great Lakes historical hybrid zone northward to central Alaska (65° N latitude), and the multivoltine, P. glaucus from this hybrid zone southward to central Florida (27° N latitude). Despite recent climate warming, no increases in mean forewing lengths of P. glaucus were observed at any major collection location (FL to MI) from the 1980s to 2013 across this long latitudinal transect (which reflects the "converse of Bergmann's size Rule", with smaller females at higher latitudes). Unlike lower latitudes, the Alaska, Ontonogon, and Chippewa/Mackinac locations (for P. canadensis) showed no significant increases in D-day accumulations, which could explain lack of size change in these northernmost locations. As a result of 3-4 decades of empirical data from major collection sites across these latitudinal clines of North America, a general "voltinism/size/D-day" model is presented, which more closely predicts female size based on D-day accumulations, than does latitude. However, local "climatic cold pockets" in northern Michigan and Wisconsin historically appeared to exert especially strong size constraints on female forewing lengths, but forewing lengths quickly increased with local summer warming during the recent decade, especially near the warming edges of the cold pockets. Results of fine-scale analyses of these "cold pockets" are in contrast to non-significant changes for other Papilio populations seen across the latitudinal transect for P. glaucus

  3. Adaptive plasticity of floral display size in animal-pollinated plants

    PubMed Central

    Harder, Lawrence D; Johnson, Steven D

    2005-01-01

    Plants need not participate passively in their own mating, despite their immobility and reliance on pollen vectors. Instead, plants may respond to their recent pollination experience by adjusting the number of flowers that they display simultaneously. Such responsiveness could arise from the dependence of floral display size on the longevity of individual flowers, which varies with pollination rate in many plant species. By hand-pollinating some inflorescences, but not others, we demonstrate plasticity in display size of the orchid Satyrium longicauda. Pollination induced flower wilting, but did not affect the opening of new flowers, so that within a few days pollinated inflorescences displayed fewer flowers than unpollinated inflorescences. During subsequent exposure to intensive natural pollination, pollen removal and receipt increased proportionally with increasing display size, whereas pollen-removal failure and self-pollination accelerated. Such benefit–cost relations allow plants that adjust display size in response to the prevailing pollination rate to increase their attractiveness when pollinators are rare (large displays), or to limit mating costs when pollinators are abundant (small displays). Seen from this perspective, pollination-induced flower wilting serves the entire plant by allowing it to display the number of flowers that is appropriate for the current pollination environment. PMID:16321788

  4. Selection for brain size impairs innate, but not adaptive immune responses

    PubMed Central

    Kotrschal, Alexander; Kolm, Niclas; Penn, Dustin J.

    2016-01-01

    Both the brain and the immune system are energetically demanding organs, and when natural selection favours increased investment into one, then the size or performance of the other should be reduced. While comparative analyses have attempted to test this potential evolutionary trade-off, the results remain inconclusive. To test this hypothesis, we compared the tissue graft rejection (an assay for measuring innate and acquired immune responses) in guppies (Poecilia reticulata) artificially selected for large and small relative brain size. Individual scales were transplanted between pairs of fish, creating reciprocal allografts, and the rejection reaction was scored over 8 days (before acquired immunity develops). Acquired immune responses were tested two weeks later, when the same pairs of fish received a second set of allografts and were scored again. Compared with large-brained animals, small-brained animals of both sexes mounted a significantly stronger rejection response to the first allograft. The rejection response to the second set of allografts did not differ between large- and small-brained fish. Our results show that selection for large brain size reduced innate immune responses to an allograft, which supports the hypothesis that there is a selective trade-off between investing into brain size and innate immunity. PMID:26962144

  5. Intraspecific variation in body size and the rate of reproduction in female insects - adaptive allometry or biophysical constraint?

    PubMed

    Berger, David; Olofsson, Martin; Friberg, Magne; Karlsson, Bengt; Wiklund, Christer; Gotthard, Karl; Gilburn, Andre

    2012-11-01

    1. A high rate of reproduction may be costly if ecological factors limit immediate reproductive output as a fast metabolism compromises own future survival. Individuals with more reserves need more time and opportunity to realize their reproductive potential. Theory therefore predicts that the reproductive rate, defined as the investment in early reproduction in proportion to total potential, should decrease with body size within species. 2. However, metabolic constraints on body size- and temperature-dependent biological rates may impede biophysical adaptation. Furthermore, the sequential manner resources that are allocated to somatic vs. reproductive tissue during ontogeny may, when juveniles develop in unpredictable environments, further contribute to non-adaptive variation in adult reproductive rates. 3. With a model on female egg laying in insects, we demonstrate how variation in body reserves is predicted to affect reproductive rate under different ecological scenarios. Small females always have higher reproductive rates but shorter lifespans. However, incorporation of female host selectivity leads to more similar reproductive rates among female size classes, and oviposition behaviour is predicted to co-evolve with reproductive rate, resulting in small females being more selective in their choice and gaining relatively more from it. 4. We fed simulations with data on the butterfly Pararge aegeria to compare model predictions with reproductive rates of wild butterflies. However, simulated reproductive allometry was a poor predictor of that observed. Instead, reproductive rates were better explained as a product of metabolic constraints on rates of egg maturation, and an empirically derived positive allometry between reproductive potential and size. However, fitness is insensitive to moderate deviations in reproductive rate when oviposition behaviour is allowed to co-evolve in the simulations, suggesting that behavioural compensation may mitigate putative

  6. Adaptations in tibial cortical thickness and total volumetric bone density in postmenopausal South Asian women with small bone size.

    PubMed

    Darling, Andrea L; Hakim, Ohood A; Horton, Khim; Gibbs, Michelle A; Cui, Liang; Berry, Jacqueline L; Lanham-New, Susan A; Hart, Kathryn H

    2013-07-01

    There is some evidence that South Asian women may have an increased risk of osteoporosis compared with Caucasian women, although whether South Asians are at increased risk of fracture is not clear. It is unknown whether older South Asian women differ from Caucasian women in bone geometry. This is the first study, to the authors' knowledge, to use peripheral Quantitative Computed Tomography (pQCT) to measure radial and tibial bone geometry in postmenopausal South Asian women. In comparison to Caucasian women, Asian women had smaller bone size at the 4% (-18% p<0.001) and 66% radius (-15% p=0.04) as well as increased total density at the 4% (+13% p=0.01) radius. For the tibia, they had a smaller bone size at the 4% (-16% p=0.005) and 14% (-38% p=0.002) sites. Also, Asians had increased cortical thickness (-17% p=0.04) at the 38% tibia, (in proportion to bone size (-30% p=0.003)). Furthermore, at the 4% and 14% tibia there were increased total densities (+12% to +29% p<0.01) and at the 14% tibia there was increased cortical density (+5% p=0.005) in Asians. These differences at the 14% and 38% (but not 4%) remained statistically significant after adjustment for Body Mass Index (BMI). These adaptations are similar to those seen previously in Chinese women. Asian women had reduced strength at the radius and tibia, evidenced by the 20-40% reduction in both polar Strength Strain Index (SSIp) and fracture load (under bending). Overall, the smaller bone size in South Asians is likely to be detrimental to bone strength, despite some adaptations in tibial cortical thickness and tibial and radial density which may partially compensate for this.

  7. Adaptive variation in offspring size in the terrestrial isopod, Armadillidium vulgare

    USGS Publications Warehouse

    Brody, M.S.; Lawlor, L.R.

    1984-01-01

    Variation in the birth size of offspring of the terrestrial isopod, Armadillidium vulgare, was observed in laboratory experiments and in field populations. In the laboratory, larger offspring were produced when the mother's food supply was reduced. In field populations, larger offspring were produced during the summer, a period of reduced food availability. Smaller offspring are produced in the spring, when food is readily available. Females may be making larger young to increase survival during the more severe conditions of the summer breeding period.

  8. Spatiotemporally modulated Vestigial gradient by Wingless signaling adaptively regulates cell division for precise wing size control.

    PubMed

    Zhu, Hao

    2011-01-07

    In animal development, the growth of a tissue or organ is timely arrested when it reaches the stereotyped correct size. How this is robustly controlled remains poorly understood. The prevalent viewpoint, which is that morphogen gradients, due to their organizing roles in development, are directly responsible for growth arrest, cannot explain a number of observations. Recent findings from studies of the Drosophila wing have revealed that the interpretation of the Wingless gradient requires signaling-induced self-inhibition and that cell proliferation is controlled by graded vestigial expression. These findings highlight a growth control mechanism that involves Wingless regulated vestigial expression, but a question is whether they can quantitatively explain the observed precision and robustness of wing size control. Quantitative and systematic investigation into Wingless signaling using a mathematical model has elucidated two points. First, negative regulation of the Vestigial gradient by Wingless signaling makes vestigial expression precise and robust. Second, weak Wingless signaling in a primarily small wing pouch causes a short and steep Vestigial gradient, which stimulates more cell divisions and leads to a significant expansion of the wing pouch; however, strong Wingless signaling in a primarily large wing pouch causes a long and smooth Vestigial gradient, which stimulates fewer cell divisions and results in a slight expansion of the wing pouch. These results substantially decipher an inherent mechanism of tissue and organ size control. Our model explains, and is supported by, a number of experimental observations.

  9. Size Exclusion Chromatography Studies of the Initial Self-Association Steps of Chicken Egg White Lysozyme Nucleation

    NASA Technical Reports Server (NTRS)

    Ewing, Felecia; Donovan, David; Pusey, Marc

    2000-01-01

    Nucleation is one of the least understood aspects of crystallogenesis. In the case of macromolecule nucleation, this understanding is further hampered by uncertainty over what precisely is being discussed. We define the process of solute self-association (aggregation, oligomerization, interaction, clustering, etc.) whereby n-mers (n > or = 2) having a crystallographic or nascent crystallographic arrangement leading to the critical nucleus reversibly form in the solution, to be part of the nucleation process. This reversible self-association process is a fundamental part of the nucleation process, and occurs as a function of the solute concentration. In the case of chicken egg white lysozyme, a considerable body of experimental evidence leads us to the conclusion that it also forms the crystal growth units. Size exclusion chromatography is a simple and direct method for determining the equilibrium constants for the self-association process. A Pharmacia FPLC system was used to provide accurate solution flow rates. The column, injection valve, and sample loop were all mounted within a temperature-controlled chamber. Chromatographically re-purified lysozyme was first dialyzed against the column equilibration buffer, with injection onto the column after several hours pre-incubation at the running temperature. Preliminary experiments, were carried out using a Toyopearl HW-50F column (1 x 50cm), equilibrated with 0.1 M sodium acetate, 5% sodium chloride, pH 4.6, at 15C. Protein concentrations from 0.1 to 4 mg/ml were employed (C(sub sat) = 1.2 mg/ml). The data from several different protein preparations consistently shows a progressively decreasing elution volume with increasing protein concentration, indicating that reversible self-association is occurring. The dotted line indicates the monomeric lysozyme elution volume. However, lysozyme interacts with the column matrix in these experiments, which complicates data analysis.Accordingly, we are testing silica-based HPLC

  10. Adapt

    NASA Astrophysics Data System (ADS)

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  11. Constant phycobilisome size in chromatically adapted cells of the cyanobacterium Tolypothrix tenuis, and variation in Nostoc sp

    SciTech Connect

    Ohki, K.; Gantt, E.; Lipschultz, C.A.; Ernst, M.C.

    1985-12-01

    Phycobilisomes of Tolypothrix tenuis, a cyanobacterium capable of complete chromatic adaptation, were studied from cells grown in red and green light, and in darkness. The phycobilisome size remained constant irrespective of the light quality. The hemidiscoidal phycobilisomes had an average diameter of about 52 nanometers and height of about 33 nanometers, by negative staining. The thickness was equivalent to a physocyanin molecule (about 10 nanometers). The molar ratio of allophycocyanin, relative to other phycobiliproteins always remained at about 1:3. Phycobilisomes from red light grown cells and cells grown heterotrophically in darkness were indistinguishable in their pigment composition, polypeptide pattern, and size. Eight polypeptides were resolved in the phycobilin region (17.5 to 23.5 kilodaltons) by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Half of these were invariable, while others were variable in green and red light. It is inferred that phycoerythrin synthesis in green light resulted in a one for one substitution of phycocyanin, thus retaining a constant phycobilisome size. Tolypothrix appears to be one of the best examples of phycobiliprotein regulation with wavelength. By contrast, in Nostoc sp., the decrease in phycoerythrin in red light cells was accompanied by a decrease in phycobilisome size but not a regulated substitution.

  12. Adaptive-filtering of trisomy 21: risk of Down syndrome depends on family size and age of previous child

    NASA Astrophysics Data System (ADS)

    Neuhäuser, Markus; Krackow, Sven

    2007-02-01

    The neonatal incidence rate of Down syndrome (DS) is well-known to accelerate strongly with maternal age. This non-linearity renders mere accumulation of defects at recombination during prolonged first meiotic prophase implausible as an explanation for DS rate increase with maternal age, but might be anticipated from chromosomal drive (CD) for trisomy 21. Alternatively, as there is selection against genetically disadvantaged embryos, the screening system that eliminates embryos with trisomy 21 might decay with maternal age. In this paper, we provide the first evidence for relaxed filtering stringency (RFS) to represent an adaptive maternal response that could explain accelerating DS rates with maternal age. Using historical data, we show that the proportion of aberrant live births decrease with increased family size in older mothers, that inter-birth intervals are longer before affected neonates than before normal ones, and that primiparae exhibit elevated levels of DS incidence at higher age. These findings are predicted by adaptive RFS but cannot be explained by the currently available alternative non-adaptive hypotheses, including CD. The identification of the relaxation control mechanism and therapeutic restoration of a stringent screen may have considerable medical implications.

  13. Facile fabrication of a silicon nanowire sensor by two size reduction steps for detection of alpha-fetoprotein biomarker of liver cancer

    NASA Astrophysics Data System (ADS)

    Binh Pham, Van; ThanhTung Pham, Xuan; Nhat Khoa Phan, Thanh; Thanh Tuyen Le, Thi; Chien Dang, Mau

    2015-12-01

    We present a facile technique that only uses conventional micro-techniques and two size-reduction steps to fabricate wafer-scale silicon nanowire (SiNW) with widths of 200 nm. Initially, conventional lithography was used to pattern SiNW with 2 μm width. Then the nanowire width was decreased to 200 nm by two size-reduction steps with isotropic wet etching. The fabricated SiNW was further investigated when used with nanowire field-effect sensors. The electrical characteristics of the fabricated SiNW devices were characterized and pH sensitivity was investigated. Then a simple and effective surface modification process was carried out to modify SiNW for subsequent binding of a desired receptor. The complete SiNW-based biosensor was then used to detect alpha-fetoprotein (AFP), one of the medically approved biomarkers for liver cancer diagnosis. Electrical measurements showed that the developed SiNW biosensor could detect AFP with concentrations of about 100 ng mL-1. This concentration is lower than the necessary AFP concentration for liver cancer diagnosis.

  14. Simulation Study on Effects of Order and Step Size of Runge-Kutta Methods that Solve Contagious Disease and Tumor Models.

    PubMed

    Z, Wang; Q, Wang; Dj, Klinke

    2016-09-01

    Biological processes such as contagious disease spread patterns and tumor growth dynamics are modelled using a set of coupled differential equations. Experimental data is usually used to calibrate models so they can be used to make future predictions. In this study, numerical methods were implemented to approximate solutions to mathematical models that were not solvable analytically, such as a SARS model. More complex models such as a tumor growth model involve high-dimensional parameter spaces; efficient numerical simulation techniques were used to search for optimal or close-to-optimal parameter values in the equations. Runge-Kutta methods are a group of explicit and implicit numerical methods that effectively solve the ordinary differential equations in these models. Effects of the order and the step size of Runge-Kutta methods were studied in order to maximize the search accuracy and efficiency in parameter spaces of the models. Numerical simulation results showed that an order of four gave the best balance between truncation errors and the simulation speed for SIR, SARS, and tumormodels studied in the project. The optimal step size for differential equation solvers was found to be model-dependent.

  15. A quantitative method for evaluating numerical simulation accuracy of time-transient Lamb wave propagation with its applications to selecting appropriate element size and time step.

    PubMed

    Wan, Xiang; Xu, Guanghua; Zhang, Qing; Tse, Peter W; Tan, Haihui

    2016-01-01

    Lamb wave technique has been widely used in non-destructive evaluation (NDE) and structural health monitoring (SHM). However, due to the multi-mode characteristics and dispersive nature, Lamb wave propagation behavior is much more complex than that of bulk waves. Numerous numerical simulations on Lamb wave propagation have been conducted to study its physical principles. However, few quantitative studies on evaluating the accuracy of these numerical simulations were reported. In this paper, a method based on cross correlation analysis for quantitatively evaluating the simulation accuracy of time-transient Lamb waves propagation is proposed. Two kinds of error, affecting the position and shape accuracies are firstly identified. Consequently, two quantitative indices, i.e., the GVE (group velocity error) and MACCC (maximum absolute value of cross correlation coefficient) derived from cross correlation analysis between a simulated signal and a reference waveform, are proposed to assess the position and shape errors of the simulated signal. In this way, the simulation accuracy on the position and shape is quantitatively evaluated. In order to apply this proposed method to select appropriate element size and time step, a specialized 2D-FEM program combined with the proposed method is developed. Then, the proper element size considering different element types and time step considering different time integration schemes are selected. These results proved that the proposed method is feasible and effective, and can be used as an efficient tool for quantitatively evaluating and verifying the simulation accuracy of time-transient Lamb wave propagation.

  16. Application of adaptive optics for controlling the NIF laser performance and spot size

    SciTech Connect

    Auerbach, J.; Bliss, E.; Henesian, M.; Lawson, J.; Manes, K.; Renard, P.; Sacks, R.; Salmon, T.; Trenholme, J.; Williams, W.; Winters, S.; Zacharias, R

    1998-08-17

    The National Ignition Facility (NIF) laser will use a 192-beam multi-pass architecture capable of delivering several MJ of UV energy in temporal pulse formats varying from sub-ns square to 20 ns precisely-defined high-contrast shapes. Each beam wavefront will be subjected to effects of optics inhomogeneities, figuring errors, mounting distortions, prompt and slow thermal effects from flashlamps, driven and passive air-path turbulence, and gravity-driven deformations. A 39-actuator intra-cavity deformable mirror, controlled by data from a 77-lenslet Hartman sensor will be used to correct these wavefront aberrations and thus to assure that stringent farfield spot requirements are met. We have developed numerical models for the expected distortions, the operation of the adaptive optic system, and the anticipated effects on beam propagation, component damage, frequency conversion, and target-plane energy distribution. These models have been extensively validated against data from LLNL's Beamlet, and Amplab lasers. We review the expected beam wavefront aberrations and their potential for adverse effects on the laser performance, describe our model of the corrective system operation, and display our predictions for corrected-beam operation of the NI

  17. Active impulsive noise control using maximum correntropy with adaptive kernel size

    NASA Astrophysics Data System (ADS)

    Lu, Lu; Zhao, Haiquan

    2017-03-01

    The active noise control (ANC) based on the principle of superposition is an attractive method to attenuate the noise signals. However, the impulsive noise in the ANC systems will degrade the performance of the controller. In this paper, a filtered-x recursive maximum correntropy (FxRMC) algorithm is proposed based on the maximum correntropy criterion (MCC) to reduce the effect of outliers. The proposed FxRMC algorithm does not requires any priori information of the noise characteristics and outperforms the filtered-x least mean square (FxLMS) algorithm for impulsive noise. Meanwhile, in order to adjust the kernel size of FxRMC algorithm online, a recursive approach is proposed through taking into account the past estimates of error signals over a sliding window. Simulation and experimental results in the context of active impulsive noise control demonstrate that the proposed algorithms achieve much better performance than the existing algorithms in various noise environments.

  18. Resistance training using eccentric overload induces early adaptations in skeletal muscle size.

    PubMed

    Norrbrand, Lena; Fluckey, James D; Pozzo, Marco; Tesch, Per A

    2008-02-01

    Fifteen healthy men performed a 5-week training program comprising four sets of seven unilateral, coupled concentric-eccentric knee extensions 2-3 times weekly. While eight men were assigned to training using a weight stack (WS) machine, seven men trained using a flywheel (FW) device, which inherently provides variable resistance and allows for eccentric overload. The design of these apparatuses ensured similar knee extensor muscle use and range of motion. Before and after training, maximal isometric force (MVC) was measured in tasks non-specific to the training modes. Volume of all individual quadriceps muscles was determined by magnetic resonance imaging. Performance across the 12 exercise sessions was measured using the inherent features of the devices. Whereas MVC increased (P < 0.05) at all angles measured in FW, such a change was less consistent in WS. There was a marked increase (P < 0.05) in task-specific performance (i.e., load lifted) in WS. Average work showed a non-significant 8.7% increase in FW. Quadriceps muscle volume increased (P < 0.025) in both groups after training. Although the more than twofold greater hypertrophy evident in FW (6.2%) was not statistically greater than that shown in WS (3.0%), all four individual quadriceps muscles of FW showed increased (P < 0.025) volume whereas in WS only m. rectus femoris was increased (P < 0.025). Collectively the results of this study suggest more robust muscular adaptations following flywheel than weight stack resistance exercise supporting the idea that eccentric overload offers a potent stimuli essential to optimize the benefits of resistance exercise.

  19. Sensori-motor adaptation to knee osteoarthritis during stepping-down before and after total knee replacement

    PubMed Central

    Mouchnino, L; Gueguen, N; Blanchard, C; Boulay, C; Gimet, G; Viton, J-M; Franceschi, J-P; Delarque, A

    2005-01-01

    Background Stepping-down is preceded by a shift of the center of mass towards the supporting side and forward. The ability to control both balance and lower limb movement was investigated in knee osteoarthritis patients before and after surgery. It was hypothesized that pain rather than knee joint mobility affects the coordination between balance and movement control. Methods The experiment was performed with 25 adult individuals. Eleven were osteoarthritic patients with damage restricted to one lower limb (8 right leg and 3 left leg). Subjects were recruited within two weeks before total knee replacement by the same orthopedic surgeon using the same prosthesis and technics of surgery. Osteoarthritic patients were tested before total knee replacement (pre-surgery session) and then, 9 of the 11 patients were tested one year after the surgery when re-educative training was completed (post-surgery session). 14 adult individuals (men: n = 7 and women: n = 7) were tested as the control group. Results The way in which the center of mass shift forward and toward the supporting side is initiated (timing and amplitude) did not vary within patients before and after surgery. In addition knee joint range of motion of the leading leg remained close to normal before and after surgery. However, the relative timing between both postural and movement phases was modified for the osteoarthritis supporting leg (unusual strategy for stepping-down) before surgery. The "coordinated" control of balance and movement turned to be a "sequential" mode of control; once the body weight transfer has been completed, the movement onset is triggered. This strategy could be aimed at shortening the duration-time supporting on the painful limb. However no such compensatory response was observed. Conclusion The change in the strategy used when supporting on the arthritis and painful limb could result from the action of nociceptors that lead to increased proprioceptor thresholds, thus gating the

  20. Silencing urease: a key evolutionary step that facilitated the adaptation of Yersinia pestis to the flea-borne transmission route.

    PubMed

    Chouikha, Iman; Hinnebusch, B Joseph

    2014-12-30

    The arthropod-borne transmission route of Yersinia pestis, the bacterial agent of plague, is a recent evolutionary adaptation. Yersinia pseudotuberculosis, the closely related food-and water-borne enteric species from which Y. pestis diverged less than 6,400 y ago, exhibits significant oral toxicity to the flea vectors of plague, whereas Y. pestis does not. In this study, we identify the Yersinia urease enzyme as the responsible oral toxin. All Y. pestis strains, including those phylogenetically closest to the Y. pseudotuberculosis progenitor, contain a mutated ureD allele that eliminated urease activity. Restoration of a functional ureD was sufficient to make Y. pestis orally toxic to fleas. Conversely, deletion of the urease operon in Y. pseudotuberculosis rendered it nontoxic. Enzymatic activity was required for toxicity. Because urease-related mortality eliminates 30-40% of infective flea vectors, ureD mutation early in the evolution of Y. pestis was likely subject to strong positive selection because it significantly increased transmission potential.

  1. Adaptive beamlet-based finite-size pencil beam dose calculation for independent verification of IMRT and VMAT

    SciTech Connect

    Park, Justin C.; Li, Jonathan G.; Arhjoul, Lahcen; Yan, Guanghua; Lu, Bo; Fan, Qiyong; Liu, Chihray

    2015-04-15

    Purpose: The use of sophisticated dose calculation procedure in modern radiation therapy treatment planning is inevitable in order to account for complex treatment fields created by multileaf collimators (MLCs). As a consequence, independent volumetric dose verification is time consuming, which affects the efficiency of clinical workflow. In this study, the authors present an efficient adaptive beamlet-based finite-size pencil beam (AB-FSPB) dose calculation algorithm that minimizes the computational procedure while preserving the accuracy. Methods: The computational time of finite-size pencil beam (FSPB) algorithm is proportional to the number of infinitesimal and identical beamlets that constitute an arbitrary field shape. In AB-FSPB, dose distribution from each beamlet is mathematically modeled such that the sizes of beamlets to represent an arbitrary field shape no longer need to be infinitesimal nor identical. As a result, it is possible to represent an arbitrary field shape with combinations of different sized and minimal number of beamlets. In addition, the authors included the model parameters to consider MLC for its rounded edge and transmission. Results: Root mean square error (RMSE) between treatment planning system and conventional FSPB on a 10 × 10 cm{sup 2} square field using 10 × 10, 2.5 × 2.5, and 0.5 × 0.5 cm{sup 2} beamlet sizes were 4.90%, 3.19%, and 2.87%, respectively, compared with RMSE of 1.10%, 1.11%, and 1.14% for AB-FSPB. This finding holds true for a larger square field size of 25 × 25 cm{sup 2}, where RMSE for 25 × 25, 2.5 × 2.5, and 0.5 × 0.5 cm{sup 2} beamlet sizes were 5.41%, 4.76%, and 3.54% in FSPB, respectively, compared with RMSE of 0.86%, 0.83%, and 0.88% for AB-FSPB. It was found that AB-FSPB could successfully account for the MLC transmissions without major discrepancy. The algorithm was also graphical processing unit (GPU) compatible to maximize its computational speed. For an intensity modulated radiation therapy (

  2. Influence of ocular chromatic aberration and pupil size on transverse resolution in ophthalmic adaptive optics optical coherence tomography.

    PubMed

    Fernández, Enrique; Drexler, Wolfgang

    2005-10-03

    Optical coherence tomography (OCT) enables visualization of the living human retina with unprecedented high axial resolution. The transverse resolution of existing OCT approaches is relatively modest as compared to other retinal imaging techniques. In this context, the use of adaptive optics (AO) to correct for ocular aberrations in combination with OCT has recently been demonstrated to notably increase the transverse resolution of the retinal OCT tomograms. AO is required when imaging is performed through moderate and large pupil sizes. A fundamental difference of OCT as compared to other imaging techniques is the demand of polychromatic light to accomplish high axial resolution. In ophthalmic OCT applications, the performance is therefore also limited by ocular chromatic aberrations. In the current work, the effects of chromatic and monochromatic ocular aberrations on the quality of retinal OCT tomograms, especially concerning transverse resolution, sensitivity and contrast, are theoretically studied and characterized. The repercussion of the chosen spectral bandwidth and pupil size on the final transverse resolution of OCT tomograms is quantitatively examined. It is found that losses in the intensity of OCT images obtained with monochromatic aberration correction can be up to 80 %, using a pupil size of 8 mm diameter in combination with a spectral bandwidth of 120 nm full width at half maximum for AO ultrahigh resolution OCT. The limits to the performance of AO for correction of monochromatic aberrations in OCT are established. The reduction of the detected signal and the resulting transverse resolution caused by chromatic aberration of the human eye is found to be strongly dependent on the employed bandwidth and pupil size. Comparison of theoretical results with experimental findings obtained in living human eyes is also provided.

  3. Monodisperse α-Fe2O3 Mesoporous Microspheres: One-Step NaCl-Assisted Microwave-Solvothermal Preparation, Size Control and Photocatalytic Property

    NASA Astrophysics Data System (ADS)

    Cao, Shao-Wen; Zhu, Ying-Jie

    2011-12-01

    A simple one-step NaCl-assisted microwave-solvothermal method has been developed for the preparation of monodisperse α-Fe2O3 mesoporous microspheres. In this approach, Fe(NO3)3 · 9H2O is used as the iron source, and polyvinylpyrrolidone (PVP) acts as a surfactant in the presence of NaCl in mixed solvents of H2O and ethanol. Under the present experimental conditions, monodisperse α-Fe2O3 mesoporous microspheres can form via oriented attachment of α-Fe2O3 nanocrystals. One of the advantages of this method is that the size of α-Fe2O3 mesoporous microspheres can be adjusted in the range from ca. 170 to ca. 260 nm by changing the experimental parameters. High photocatalytic activities in the degradation of salicylic acid are observed for α-Fe2O3 mesoporous microspheres with different specific surface areas.

  4. Nonstandard Finite Difference Schemes: Relations Between Time and Space Step-Sizes in Numerical Schemes for PDE's That Follow from Positivity Condition

    NASA Technical Reports Server (NTRS)

    Mickens, Ronald E.

    1996-01-01

    A large class of physical phenomena can be modeled by evolution and wave type Partial Differential Equations (PDE). Few of these equations have known explicit exact solutions. Finite-difference techniques are a popular method for constructing discrete representations of these equations for the purpose of numerical integration. However, the solutions to the difference equations often contain so called numerical instabilities; these are solutions to the difference equations that do not correspond to any solution of the PDE's. For explicit schemes, the elimination of this behavior requires functional relations to exist between the time and space steps-sizes. We show that such functional relations can be obtained for certain PDE's by use of a positivity condition. The PDE's studied are the Burgers, Fisher, and linearized Euler equations.

  5. Monodisperse α-Fe2O3 Mesoporous Microspheres: One-Step NaCl-Assisted Microwave-Solvothermal Preparation, Size Control and Photocatalytic Property.

    PubMed

    Cao, Shao-Wen; Zhu, Ying-Jie

    2010-08-18

    A simple one-step NaCl-assisted microwave-solvothermal method has been developed for the preparation of monodisperse α-Fe2O3 mesoporous microspheres. In this approach, Fe(NO3)3 · 9H2O is used as the iron source, and polyvinylpyrrolidone (PVP) acts as a surfactant in the presence of NaCl in mixed solvents of H2O and ethanol. Under the present experimental conditions, monodisperse α-Fe2O3 mesoporous microspheres can form via oriented attachment of α-Fe2O3 nanocrystals. One of the advantages of this method is that the size of α-Fe2O3 mesoporous microspheres can be adjusted in the range from ca. 170 to ca. 260 nm by changing the experimental parameters. High photocatalytic activities in the degradation of salicylic acid are observed for α-Fe2O3 mesoporous microspheres with different specific surface areas.

  6. Adaptive sliding mode back-stepping pitch angle control of a variable-displacement pump controlled pitch system for wind turbines.

    PubMed

    Yin, Xiu-xing; Lin, Yong-gang; Li, Wei; Liu, Hong-wei; Gu, Ya-jing

    2015-09-01

    A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines. The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set. The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set. The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed. An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties. The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine.

  7. Optimizing trial design in pharmacogenetics research: comparing a fixed parallel group, group sequential, and adaptive selection design on sample size requirements.

    PubMed

    Boessen, Ruud; van der Baan, Frederieke; Groenwold, Rolf; Egberts, Antoine; Klungel, Olaf; Grobbee, Diederick; Knol, Mirjam; Roes, Kit

    2013-01-01

    Two-stage clinical trial designs may be efficient in pharmacogenetics research when there is some but inconclusive evidence of effect modification by a genomic marker. Two-stage designs allow to stop early for efficacy or futility and can offer the additional opportunity to enrich the study population to a specific patient subgroup after an interim analysis. This study compared sample size requirements for fixed parallel group, group sequential, and adaptive selection designs with equal overall power and control of the family-wise type I error rate. The designs were evaluated across scenarios that defined the effect sizes in the marker positive and marker negative subgroups and the prevalence of marker positive patients in the overall study population. Effect sizes were chosen to reflect realistic planning scenarios, where at least some effect is present in the marker negative subgroup. In addition, scenarios were considered in which the assumed 'true' subgroup effects (i.e., the postulated effects) differed from those hypothesized at the planning stage. As expected, both two-stage designs generally required fewer patients than a fixed parallel group design, and the advantage increased as the difference between subgroups increased. The adaptive selection design added little further reduction in sample size, as compared with the group sequential design, when the postulated effect sizes were equal to those hypothesized at the planning stage. However, when the postulated effects deviated strongly in favor of enrichment, the comparative advantage of the adaptive selection design increased, which precisely reflects the adaptive nature of the design.

  8. Compact polymeric four-wavelength multiplexers based on cascaded step-size MMI for 1G/10G hybrid TDM-PON applications.

    PubMed

    Fan, Shu-Hao; Guidotti, Daniel; Chien, Hung-Chang; Chang, Gee-Kung

    2008-08-18

    A novel polymeric four-wavelength multiplexer based on a new design concept of cascaded step-size multimode interferometer (CSS-MMI) is first presented. It can be fabricated by using planar lightwave circuit (PLC) technology and is highly compatible with both current 1-Gbps and future 10Gbps optical transceivers for applications in next generation 1-Gbps and 10-Gbps coexisting time-division-multiplexed passive optical network (TDM PON). By combining two types of proposed CSS-MMI 1??2 wavelength splitters, a compact 1.5cm-long four wavelength multiplexer is realized without requiring complicated design and tedious calculation. In addition, the upstream wavelength channel at 1310 nm has 0.18 dB low insertion loss and three downstream wavelength channels at 1490 nm, 1550 nm and 1590 nm exhibit insertion losses of 1.21 dB, 1.34 dB and 1.02 dB, respectively, with their extinction ratios ranging from 11.71 dB to 32.07 dB.

  9. Crystal-Size Effects on Carbon Dioxide Capture of a Covalently Alkylamine-Tethered Metal-Organic Framework Constructed by a One-Step Self-Assembly

    PubMed Central

    Kim, Yun Kyeong; Hyun, Sung-min; Lee, Jae Hwa; Kim, Tae Kyung; Moon, Dohyun; Moon, Hoi Ri

    2016-01-01

    To enhance the carbon dioxide (CO2) uptake of metal-organic frameworks (MOFs), amine functionalization of their pore surfaces has been studied extensively. In general, amine-functionalized MOFs have been synthesized via post-synthetic modifications. Herein, we introduce a one-step construction of a MOF ([(NiLethylamine)(BPDC)] = MOFNH2; [NiLethylamine]2+ = [Ni(C12H32N8)]2+; BPDC2− = 4,4‘-biphenyldicarboxylate) possessing covalently tethered alkylamine groups without post-synthetic modification. Two-amine groups per metal centre were introduced by this method. MOFNH2 showed enhanced CO2 uptake at elevated temperatures, attributed to active chemical interactions between the amine groups and the CO2 molecules. Due to the narrow channels of MOFNH2, the accessibility to the channel of CO2 is the limiting factor in its sorption behaviour. In this context, only crystal size reduction of MOFNH2 led to much faster and greater CO2 uptake at low pressures. PMID:26757890

  10. Particle Swarm Optimization and Varying Chemotactic Step-Size Bacterial Foraging Optimization Algorithms Based Dynamic Economic Dispatch with Non-smooth Fuel Cost Functions

    NASA Astrophysics Data System (ADS)

    Praveena, P.; Vaisakh, K.; Rama Mohana Rao, S.

    The Dynamic economic dispatch (DED) problem is an optimization problem with an objective to determine the optimal combination of power outputs for all generating units over a certain period of time in order to minimize the total fuel cost while satisfying dynamic operational constraints and load demand in each interval. Recently social foraging behavior of Escherichia coli bacteria has been explored to develop a novel algorithm for distributed optimization and control. The Bacterial Foraging Optimization Algorithm (BFOA) is currently gaining popularity in the community of researchers, for its effectiveness in solving certain difficult real-world optimization problems. This article comes up with a hybrid approach involving Particle Swarm Optimization (PSO) and BFO algorithms with varying chemo tactic step size for solving the DED problem of generating units considering valve-point effects. The proposed hybrid algorithm has been extensively compared with those methods reported in the literature. The new method is shown to be statistically significantly better on two test systems consisting of five and ten generating units.

  11. Solution of two-dimensional electromagnetic scattering problem by FDTD with optimal step size, based on a semi-norm analysis

    SciTech Connect

    Monsefi, Farid; Carlsson, Linus; Silvestrov, Sergei; Rančić, Milica; Otterskog, Magnus

    2014-12-10

    To solve the electromagnetic scattering problem in two dimensions, the Finite Difference Time Domain (FDTD) method is used. The order of convergence of the FDTD algorithm, solving the two-dimensional Maxwell’s curl equations, is estimated in two different computer implementations: with and without an obstacle in the numerical domain of the FDTD scheme. This constitutes an electromagnetic scattering problem where a lumped sinusoidal current source, as a source of electromagnetic radiation, is included inside the boundary. Confined within the boundary, a specific kind of Absorbing Boundary Condition (ABC) is chosen and the outside of the boundary is in form of a Perfect Electric Conducting (PEC) surface. Inserted in the computer implementation, a semi-norm has been applied to compare different step sizes in the FDTD scheme. First, the domain of the problem is chosen to be the free-space without any obstacles. In the second part of the computer implementations, a PEC surface is included as the obstacle. The numerical instability of the algorithms can be rather easily avoided with respect to the Courant stability condition, which is frequently used in applying the general FDTD algorithm.

  12. Crystal-Size Effects on Carbon Dioxide Capture of a Covalently Alkylamine-Tethered Metal-Organic Framework Constructed by a One-Step Self-Assembly

    NASA Astrophysics Data System (ADS)

    Kim, Yun Kyeong; Hyun, Sung-Min; Lee, Jae Hwa; Kim, Tae Kyung; Moon, Dohyun; Moon, Hoi Ri

    2016-01-01

    To enhance the carbon dioxide (CO2) uptake of metal-organic frameworks (MOFs), amine functionalization of their pore surfaces has been studied extensively. In general, amine-functionalized MOFs have been synthesized via post-synthetic modifications. Herein, we introduce a one-step construction of a MOF ([(NiLethylamine)(BPDC)] = MOFNH2 [NiLethylamine]2+ = [Ni(C12H32N8)]2+ BPDC2‑ = 4,4‘-biphenyldicarboxylate) possessing covalently tethered alkylamine groups without post-synthetic modification. Two-amine groups per metal centre were introduced by this method. MOFNH2 showed enhanced CO2 uptake at elevated temperatures, attributed to active chemical interactions between the amine groups and the CO2 molecules. Due to the narrow channels of MOFNH2, the accessibility to the channel of CO2 is the limiting factor in its sorption behaviour. In this context, only crystal size reduction of MOFNH2 led to much faster and greater CO2 uptake at low pressures.

  13. Using a generational time-step model to simulate dynamics of adaptation to transgenic corn and crop rotation by western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Crowder, D W; Onstad, D W

    2005-04-01

    We expanded a simulation model of the population dynamics and genetics of the western corn rootworm for a landscape of corn, soybean, and other crops to study the simultaneous development of resistance to both crop rotation and transgenic corn. Transgenic corn effective against corn rootworm was recently approved in 2003 and may be a very effective new technology for control of western corn rootworm in areas with or without the rotation-resistant variant. In simulations of areas with rotation-resistant populations, planting transgenic corn to only rotated cornfields was a robust strategy to prevent resistance to both traits. In these areas, planting transgenic corn to only continuous fields was not an effective strategy for preventing adaptation to crop rotation or transgenic corn. In areas without rotation-resistant phenotypes, gene expression of the allele for resistance to transgenic corn was the most important factor affecting the development of resistance to transgenic corn. If the allele for resistance to transgenic corn is recessive, resistance can be delayed longer than 15 yr, but if the resistant allele is dominant then resistance usually developed within 15 yr. In a sensitivity analysis, among the parameters investigated, initial allele frequency and density dependence were the two most important factors affecting the evolution of resistance. We compared the results of this simulation model with a more complicated model and results between the two were similar. This indicates that results from a simpler model with a generational time-step can compare favorably with a more complex model with a daily time-step.

  14. The collapsed cone algorithm for 192Ir dosimetry using phantom-size adaptive multiple-scatter point kernels

    NASA Astrophysics Data System (ADS)

    Carlsson Tedgren, Åsa; Plamondon, Mathieu; Beaulieu, Luc

    2015-07-01

    The aim of this work was to investigate how dose distributions calculated with the collapsed cone (CC) algorithm depend on the size of the water phantom used in deriving the point kernel for multiple scatter. A research version of the CC algorithm equipped with a set of selectable point kernels for multiple-scatter dose that had initially been derived in water phantoms of various dimensions was used. The new point kernels were generated using EGSnrc in spherical water phantoms of radii 5 cm, 7.5 cm, 10 cm, 15 cm, 20 cm, 30 cm and 50 cm. Dose distributions derived with CC in water phantoms of different dimensions and in a CT-based clinical breast geometry were compared to Monte Carlo (MC) simulations using the Geant4-based brachytherapy specific MC code Algebra. Agreement with MC within 1% was obtained when the dimensions of the phantom used to derive the multiple-scatter kernel were similar to those of the calculation phantom. Doses are overestimated at phantom edges when kernels are derived in larger phantoms and underestimated when derived in smaller phantoms (by around 2% to 7% depending on distance from source and phantom dimensions). CC agrees well with MC in the high dose region of a breast implant and is superior to TG43 in determining skin doses for all multiple-scatter point kernel sizes. Increased agreement between CC and MC is achieved when the point kernel is comparable to breast dimensions. The investigated approximation in multiple scatter dose depends on the choice of point kernel in relation to phantom size and yields a significant fraction of the total dose only at distances of several centimeters from a source/implant which correspond to volumes of low doses. The current implementation of the CC algorithm utilizes a point kernel derived in a comparatively large (radius 20 cm) water phantom. A fixed point kernel leads to predictable behaviour of the algorithm with the worst case being a source/implant located well within a patient

  15. The collapsed cone algorithm for (192)Ir dosimetry using phantom-size adaptive multiple-scatter point kernels.

    PubMed

    Tedgren, Åsa Carlsson; Plamondon, Mathieu; Beaulieu, Luc

    2015-07-07

    The aim of this work was to investigate how dose distributions calculated with the collapsed cone (CC) algorithm depend on the size of the water phantom used in deriving the point kernel for multiple scatter. A research version of the CC algorithm equipped with a set of selectable point kernels for multiple-scatter dose that had initially been derived in water phantoms of various dimensions was used. The new point kernels were generated using EGSnrc in spherical water phantoms of radii 5 cm, 7.5 cm, 10 cm, 15 cm, 20 cm, 30 cm and 50 cm. Dose distributions derived with CC in water phantoms of different dimensions and in a CT-based clinical breast geometry were compared to Monte Carlo (MC) simulations using the Geant4-based brachytherapy specific MC code Algebra. Agreement with MC within 1% was obtained when the dimensions of the phantom used to derive the multiple-scatter kernel were similar to those of the calculation phantom. Doses are overestimated at phantom edges when kernels are derived in larger phantoms and underestimated when derived in smaller phantoms (by around 2% to 7% depending on distance from source and phantom dimensions). CC agrees well with MC in the high dose region of a breast implant and is superior to TG43 in determining skin doses for all multiple-scatter point kernel sizes. Increased agreement between CC and MC is achieved when the point kernel is comparable to breast dimensions. The investigated approximation in multiple scatter dose depends on the choice of point kernel in relation to phantom size and yields a significant fraction of the total dose only at distances of several centimeters from a source/implant which correspond to volumes of low doses. The current implementation of the CC algorithm utilizes a point kernel derived in a comparatively large (radius 20 cm) water phantom. A fixed point kernel leads to predictable behaviour of the algorithm with the worst case being a source/implant located well within a patient

  16. Security: Step by Step

    ERIC Educational Resources Information Center

    Svetcov, Eric

    2005-01-01

    This article provides a list of the essential steps to keeping a school's or district's network safe and sound. It describes how to establish a security architecture and approach that will continually evolve as the threat environment changes over time. The article discusses the methodology for implementing this approach and then discusses the…

  17. A low-complexity 2-point step size gradient projection method with selective function evaluations for smoothed total variation based CBCT reconstructions

    NASA Astrophysics Data System (ADS)

    Song, Bongyong; Park, Justin C.; Song, William Y.

    2014-11-01

    The Barzilai-Borwein (BB) 2-point step size gradient method is receiving attention for accelerating Total Variation (TV) based CBCT reconstructions. In order to become truly viable for clinical applications, however, its convergence property needs to be properly addressed. We propose a novel fast converging gradient projection BB method that requires ‘at most one function evaluation’ in each iterative step. This Selective Function Evaluation method, referred to as GPBB-SFE in this paper, exhibits the desired convergence property when it is combined with a ‘smoothed TV’ or any other differentiable prior. This way, the proposed GPBB-SFE algorithm offers fast and guaranteed convergence to the desired 3DCBCT image with minimal computational complexity. We first applied this algorithm to a Shepp-Logan numerical phantom. We then applied to a CatPhan 600 physical phantom (The Phantom Laboratory, Salem, NY) and a clinically-treated head-and-neck patient, both acquired from the TrueBeam™ system (Varian Medical Systems, Palo Alto, CA). Furthermore, we accelerated the reconstruction by implementing the algorithm on NVIDIA GTX 480 GPU card. We first compared GPBB-SFE with three recently proposed BB-based CBCT reconstruction methods available in the literature using Shepp-Logan numerical phantom with 40 projections. It is found that GPBB-SFE shows either faster convergence speed/time or superior convergence property compared to existing BB-based algorithms. With the CatPhan 600 physical phantom, the GPBB-SFE algorithm requires only 3 function evaluations in 30 iterations and reconstructs the standard, 364-projection FDK reconstruction quality image using only 60 projections. We then applied the algorithm to a clinically-treated head-and-neck patient. It was observed that the GPBB-SFE algorithm requires only 18 function evaluations in 30 iterations. Compared with the FDK algorithm with 364 projections, the GPBB-SFE algorithm produces visibly equivalent quality CBCT

  18. A low-complexity 2-point step size gradient projection method with selective function evaluations for smoothed total variation based CBCT reconstructions.

    PubMed

    Song, Bongyong; Park, Justin C; Song, William Y

    2014-11-07

    The Barzilai-Borwein (BB) 2-point step size gradient method is receiving attention for accelerating Total Variation (TV) based CBCT reconstructions. In order to become truly viable for clinical applications, however, its convergence property needs to be properly addressed. We propose a novel fast converging gradient projection BB method that requires 'at most one function evaluation' in each iterative step. This Selective Function Evaluation method, referred to as GPBB-SFE in this paper, exhibits the desired convergence property when it is combined with a 'smoothed TV' or any other differentiable prior. This way, the proposed GPBB-SFE algorithm offers fast and guaranteed convergence to the desired 3DCBCT image with minimal computational complexity. We first applied this algorithm to a Shepp-Logan numerical phantom. We then applied to a CatPhan 600 physical phantom (The Phantom Laboratory, Salem, NY) and a clinically-treated head-and-neck patient, both acquired from the TrueBeam™ system (Varian Medical Systems, Palo Alto, CA). Furthermore, we accelerated the reconstruction by implementing the algorithm on NVIDIA GTX 480 GPU card. We first compared GPBB-SFE with three recently proposed BB-based CBCT reconstruction methods available in the literature using Shepp-Logan numerical phantom with 40 projections. It is found that GPBB-SFE shows either faster convergence speed/time or superior convergence property compared to existing BB-based algorithms. With the CatPhan 600 physical phantom, the GPBB-SFE algorithm requires only 3 function evaluations in 30 iterations and reconstructs the standard, 364-projection FDK reconstruction quality image using only 60 projections. We then applied the algorithm to a clinically-treated head-and-neck patient. It was observed that the GPBB-SFE algorithm requires only 18 function evaluations in 30 iterations. Compared with the FDK algorithm with 364 projections, the GPBB-SFE algorithm produces visibly equivalent quality CBCT image for

  19. Role of adaptive and non-adaptive mechanisms forming complex patterns of genome size variation in six cytotypes of polyploid Allium oleraceum (Amaryllidaceae) on a continental scale

    PubMed Central

    Duchoslav, Martin; Šafářová, Lenka; Jandová, Michaela

    2013-01-01

    Background and Aims Although the large variation in genome size among different species is widely acknowledged, the occurrence and extent of variation below the species level are still controversial and have not yet been satisfactorily analysed. The aim of this study was to assess genome size variation in six ploidy levels (2n = 3x–8x) of the polyploid Allium oleraceum over a large geographical gradient and to search for potential interpretations of the size variation. Methods The genome sizes of 407 individuals of A. oleraceum collected from 114 populations across Europe were determined by flow cytometry using propidium iodide staining. The genome size variation was correlated with spatial, climatic and habitat variables. Key Results The mean holoploid genome size (2C DNA) was 42·49, 52·14, 63·34, 71·94, 85·51 and 92·12 pg at the tri-, tetra-, penta-, hexa-, hepta- and octoploid levels, respectively. Genome size varied from a minimum of 2·3 % in the octoploids to a maximum of 18·3 % in the tetraploids. Spatial structuring of genome size was observed within the tetra- and pentaploids, where 2C DNA significantly increased with both latitude and longitude, and correlated with several climatic variables, suggesting a gradient of continentality. Genome size in hexaploids showed low variation, weak correlation with climatic variables and no spatial structuring. Downsizing in monoploid genome size was observed between all cytotypes except for heptaploids. Splitting populations into western and eastern European groups resulted in strong differences in monoploid genome size between groups in tetra- and pentaploids but not in hexaploids. The monoploid genome sizes of the cytotypes were similar in the western group but diverged in the eastern group. Conclusions Complex patterns of holoploid and monoploid genome size variation found both within and between A. oleraceum cytotypes are most likely the result of several interacting factors, including different

  20. Adaptive re-tracking algorithm for retrieval of water level variations and wave heights from satellite altimetry data for middle-sized inland water bodies

    NASA Astrophysics Data System (ADS)

    Troitskaya, Yuliya; Lebedev, Sergey; Soustova, Irina; Rybushkina, Galina; Papko, Vladislav; Baidakov, Georgy; Panyutin, Andrey

    by the improved threshold algorithm. The possibility of determination of significant wave height (SWH) in the lakes through a two-step adaptive retracking is also studied. Calculation of the parameter SWH for Gorky Reservoir from May 2010 to March 2014 showed the anomalously high values of SWH, derived from altimetry data [15], which means that the calibration of this SWH for inland waters is required. Calibration ground measurements were performed at Gorky reservoir in 2011-2013, when wave height, wind speed and air temperature were collected by equipment placed on a buoy [15] collocated with Jason-1 and Jason-2 altimetry data acquisition. The results obtained on the basis of standard algorithm and method for adaptive re-tracking at Rybinsk , Gorky , Kuibyshev , Saratov and Volgograd reservoirs and middle-sized lakes of Russia: Chany, Segozero, Hanko, Oneko, Beloye, water areas of which are intersected by the Jason-1,2 tracks, were compared and their correlation with the observed data of hydrological stations in reservoirs and lakes was investigated. It was noted that the Volgograd reservoir regional re-tracking to determine the water level , while the standard GDR data are practically absent. REFERENCES [1] AVISO/Altimetry. User Handbook. Merged TOPEX/ POSEIDON Products. Edition 3.0. AVISO. Toulouse., 1996. [2] C.M. Birkett et al., “Surface water dynamics in the Amazon Basin: Application of satellite radar altimetry,” J. Geophys. Res., vol. 107, pp. 8059, 2002. [3] G. Brown, “The average impulse response of a rough surface and its applications,” IEEE Trans. Antennas Propagat., vol. 25, pp. 67-74, 1977. [4] I.O. Campos et al., “Temporal variations of river basin waters from Topex/Poseidon satellite altimetry. Application to the Amazon basin,” Earth and Planetary Sciences, vol. 333, pp. 633-643, 2001. [5] A.V. Kouraev et al., “Ob’ river discharge from TOPEX/Poseidon satellite altimetry (1992-2002),” Rem. Sens. Environ., vol. 93, pp. 238-245, 2004

  1. The stellar mass-size relation for cluster galaxies at z = 1 with high angular resolution from the Gemini/GeMS multiconjugate adaptive optics system

    NASA Astrophysics Data System (ADS)

    Sweet, Sarah M.; Sharp, Robert; Glazebrook, Karl; Rigaut, Francois; Carrasco, Eleazar R.; Brodwin, Mark; Bayliss, Matthew; Stalder, Brian; Abraham, Roberto; McGregor, Peter

    2017-01-01

    We present the stellar mass-size relation for 49 galaxies within the z = 1.067 cluster SPT-CL J0546-5345, with full width at half-maximum ˜80-120 mas Ks-band data from the Gemini multiconjugate adaptive optics system (GeMS/GSAOI). This is the first such measurement in a cluster environment, performed at sub-kpc resolution at rest-frame wavelengths dominated by the light of the underlying old stellar populations. The observed stellar mass-size relation is offset from the local relation by 0.21 dex, corresponding to a size evolution proportional to (1 + z)-1.25, consistent with the literature. The slope of the stellar mass-size relation β = 0.74 ± 0.06, consistent with the local relation. The absence of slope evolution indicates that the amount of size growth is constant with stellar mass. This suggests that galaxies in massive clusters such as SPT-CL J0546-5345 grow via processes that increase the size without significant morphological interference, such as minor mergers and/or adiabatic expansion. The slope of the cluster stellar mass-size relation is significantly shallower if measured in Hubble Space Telescope (HST)/Advanced Camera for Surveys imaging at wavelengths blueward of the Balmer break, similar to rest-frame ultraviolet relations at z = 1 in the literature. The stellar mass-size relation must be measured at redder wavelengths, which are more sensitive to the old stellar population that dominates the stellar mass of the galaxies. The slope is unchanged when GeMS Ks-band imaging is degraded to the resolution of K-band HST/Near Infrared Camera and Multi-Object Spectrometer resolution but dramatically affected when degraded to Ks-band Magellan/FourStar resolution. Such measurements must be made with adaptive optics in order to accurately characterize the sizes of compact, z = 1 galaxies.

  2. Next Step for STEP

    SciTech Connect

    Wood, Claire; Bremner, Brenda

    2013-08-09

    The Siletz Tribal Energy Program (STEP), housed in the Tribe’s Planning Department, will hire a data entry coordinator to collect, enter, analyze and store all the current and future energy efficiency and renewable energy data pertaining to administrative structures the tribe owns and operates and for homes in which tribal members live. The proposed data entry coordinator will conduct an energy options analysis in collaboration with the rest of the Siletz Tribal Energy Program and Planning Department staff. An energy options analysis will result in a thorough understanding of tribal energy resources and consumption, if energy efficiency and conservation measures being implemented are having the desired effect, analysis of tribal energy loads (current and future energy consumption), and evaluation of local and commercial energy supply options. A literature search will also be conducted. In order to educate additional tribal members about renewable energy, we will send four tribal members to be trained to install and maintain solar panels, solar hot water heaters, wind turbines and/or micro-hydro.

  3. Beyond "One Size Fits All": Physician Nonverbal Adaptability to Patients' Need for Paternalism and Its Positive Consultation Outcomes.

    PubMed

    Carrard, Valérie; Schmid Mast, Marianne; Cousin, Gaëtan

    2016-11-01

    In this study, we tested whether physicians' ability to adapt their nonverbal behavior to their patients' preferences for a paternalistic interaction style is related to positive consultation outcomes. We hypothesized that the more physicians adapt their nonverbal dominance behavior to match their patients' preferences for physician paternalism, the more positively the patients perceive the medical interaction. We assessed the actual nonverbal dominance behavior of 32 general practitioners when interacting with two of their patients and compared it with each of their patients' preferences for paternalism to obtain a measure of adaptability. Additionally, we measured patient outcomes with a questionnaire assessing patient satisfaction, trust in the physician, and evaluation of physician competence. Results show that the more nonverbal dominance the physician shows toward the patient who prefers a more paternalistic physician, as compared to toward the patient who prefers a less paternalistic physician (i.e., the more the physician shows nonverbal behavioral adaptability), the more positive the consultation outcomes are. This means that physicians' ability to adapt aspects of their nonverbal dominance behavior to their individual patients' preferences is related to better outcomes for patients. As this study shows, it is advantageous for patients when a physician behaves flexibly instead of showing the same behavior towards all patients. Physician training might want to focus more on teaching a diversity of different behavior repertoires instead of a given set of behaviors.

  4. Niche expansion leads to small-scale adaptive divergence along an elevation gradient in a medium-sized passerine bird

    PubMed Central

    McCormack, John E; Smith, Thomas B

    2008-01-01

    Niche expansion can lead to adaptive differentiation and speciation, but there are few examples from contemporary niche expansions about how this process is initiated. We assess the consequences of a niche expansion by Mexican jays (Aphelocoma ultramarina) along an elevation gradient. We predicted that jays at high elevation would have straighter bills adapted to feeding on pine cones, whereas jays at low elevation would have hooked bills adapted to feeding on acorns. We measured morphological and genetic variation of 95 adult jays and found significant differences in hook length between elevations in accordance with predictions, a pattern corroborated by analysis at the regional scale. Genetic results from microsatellite and mtDNA variation support phenotypic differentiation in the presence of gene flow coupled with weak, but detectable genetic differentiation between high- and low-elevation populations. These results demonstrate that niche expansion can lead to adaptive divergence despite gene flow between parapatric populations along an elevation gradient, providing information on a key precursor to ecological speciation. PMID:18544512

  5. Adaptations to “Thermal Time” Constraints in Papilio: Latitudinal and Local Size Clines Differ in Response to Regional Climate Change

    PubMed Central

    Scriber, J. Mark; Elliot, Ben; Maher, Emily; McGuire, Molly; Niblack, Marjie

    2014-01-01

    Adaptations to “thermal time” (=Degree-day) constraints on developmental rates and voltinism for North American tiger swallowtail butterflies involve most life stages, and at higher latitudes include: smaller pupae/adults; larger eggs; oviposition on most nutritious larval host plants; earlier spring adult emergences; faster larval growth and shorter molting durations at lower temperatures. Here we report on forewing sizes through 30 years for both the northern univoltine P. canadensis (with obligate diapause) from the Great Lakes historical hybrid zone northward to central Alaska (65° N latitude), and the multivoltine, P. glaucus from this hybrid zone southward to central Florida (27° N latitude). Despite recent climate warming, no increases in mean forewing lengths of P. glaucus were observed at any major collection location (FL to MI) from the 1980s to 2013 across this long latitudinal transect (which reflects the “converse of Bergmann’s size Rule”, with smaller females at higher latitudes). Unlike lower latitudes, the Alaska, Ontonogon, and Chippewa/Mackinac locations (for P. canadensis) showed no significant increases in D-day accumulations, which could explain lack of size change in these northernmost locations. As a result of 3–4 decades of empirical data from major collection sites across these latitudinal clines of North America, a general “voltinism/size/D-day” model is presented, which more closely predicts female size based on D-day accumulations, than does latitude. However, local “climatic cold pockets” in northern Michigan and Wisconsin historically appeared to exert especially strong size constraints on female forewing lengths, but forewing lengths quickly increased with local summer warming during the recent decade, especially near the warming edges of the cold pockets. Results of fine-scale analyses of these “cold pockets” are in contrast to non-significant changes for other Papilio populations seen across the latitudinal

  6. Size-changeable x-ray beam collimation using an adaptive x-ray optical system based on four deformable mirrors

    NASA Astrophysics Data System (ADS)

    Goto, T.; Matsuyama, S.; Nakamori, H.; Hayashi, H.; Sano, Y.; Kohmura, Y.; Yabashi, M.; Ishikawa, T.; Yamauchi, K.

    2016-09-01

    A two-stage adaptive optical system using four piezoelectric deformable mirrors was constructed at SPring-8 to form collimated X-ray beams. The deformable mirrors were finely deformed to target shapes (elliptical for the upstream mirrors and parabolic for the downstream mirrors) based on shape data measured with the X-ray pencil beam scanning method. Ultraprecise control of the mirror shapes enables us to obtain various collimated beams with different beam sizes of 314 μm (358 μm) and 127 μm (65 μm) in the horizontal (vertical) directions, respectively, with parallelism accuracy of 1 μrad rms.

  7. Adaptive plasticity of egg size in response to competition in the cowpea weevil, Callosobruchus maculatus (Coleoptera: Bruchidae).

    PubMed

    Kawecki, Tadeusz J

    1995-04-01

    Life history theory predicts that larger propagules should be produced when the offspring are expected to experience intense competition. This study tested whether female cowpea weevils responded to high larval or adult density by producing larger eggs. In a splitbrood design I measured the effect of density experienced by females at their larval stage (1 vs. 4-6 larvae/cowpea) on the size of eggs produced just after emergence. The females were then kept either at low adult density (1 female+1 male per vial), or at high adult density (10 females+10 males) for 2 days, and tested for the effect of this adult density treatment on the size of eggs laid subsequently. I measured egg length and width, as well as the diameter of the entrance tunnel made by the larva, which can be regarded as a crude measure of larval size. Females that experienced high adult density subsequently laid slightly wider eggs than those kept at low density. This difference, albeit small (about 1-4% after correction for female weight and the effect of family, depending on the statistical model used), was statistically significant and robust to alterations of the statistical model. It may be a remnant of a larger plastic response of egg size to competition that has become eroded during many generations in high-density laboratory cultures. There was no difference in egg length or the diameter of the entrance tunnel. Eggs laid just after emergence by females reared at high larval density also tended to be wider than those produced by females that had no competitors. This effect was only marginally significant, however, and sensitive to the statistical model. Both egg length and width and the diameter of the entrance tunnel increased with female weight and decreased with female age. The tunnel diameter was positively correlated with both egg length and width, but the effect of width was larger.

  8. Adaptive changes in size and age at metamorphosis can qualitatively vary with predator type and available defenses.

    PubMed

    Higginson, A D; Ruxton, G D

    2010-09-01

    In many taxa the timing of metamorphosis is plastic in response to predation risk during the pre-metamorphic stage, and trends in both age and body size at metamorphosis have been the subject of much study. The responses to cues of predators are predominantly to be larger or equal-sized at the same age or older at metamorphosis. These observations are in direct contrast with existing theoretical treatments of this plasticity, which mostly predict earlier and smaller metamorphosis and never later and larger metamorphosis without invoking indirect effects on growth rate. Here we resolve the discrepancy between theory and observation using a dynamic state-dependent model that incorporates morphological and behavioral responses to predation risk. We allow prey to choose the optimal activity level and/or investment in defense over the growth period. We show that under certain conditions, metamorphosis at a larger size and later time is likely to be optimal. Our analysis allows us to make testable predictions about the changes in activity level of prey as they grow and how the effect of providing refuges will vary with predator type. Several of these predictions are supported by a meta-analysis of metamorphic responses to caged predators by larval amphibians and insects. Our predictions lead to insights about the feedback effects of antipredator responses on growth and subsequent implications for life history.

  9. The adaptive computer-aided diagnosis system based on tumor sizes for the classification of breast tumors detected at screening ultrasound.

    PubMed

    Moon, Woo Kyung; Chen, I-Ling; Chang, Jung Min; Shin, Sung Ui; Lo, Chung-Ming; Chang, Ruey-Feng

    2017-04-01

    Screening ultrasound (US) is increasingly used as a supplement to mammography in women with dense breasts, and more than 80% of cancers detected by US alone are 1cm or smaller. An adaptive computer-aided diagnosis (CAD) system based on tumor size was proposed to classify breast tumors detected at screening US images using quantitative morphological and textural features. In the present study, a database containing 156 tumors (78 benign and 78 malignant) was separated into two subsets of different tumor sizes (<1cm and ⩾1cm) to explore the improvement in the performance of the CAD system. After adaptation, the accuracies, sensitivities, specificities and Az values of the CAD for the entire database increased from 73.1% (114/156), 73.1% (57/78), 73.1% (57/78), and 0.790 to 81.4% (127/156), 83.3% (65/78), 79.5% (62/78), and 0.852, respectively. In the data subset of tumors larger than 1cm, the performance improved from 66.2% (51/77), 68.3% (28/41), 63.9% (23/36), and 0.703 to 81.8% (63/77), 85.4% (35/41), 77.8% (28/36), and 0.855, respectively. The proposed CAD system can be helpful to classify breast tumors detected at screening US.

  10. Innoversity in knowledge-for-action and adaptation to climate change: the first steps of an 'evidence-based climatic health' transfrontier training program.

    PubMed

    Lapaige, Véronique; Essiembre, Hélène

    2010-01-01

    It has become increasingly clear to the international scientific community that climate change is real and has important consequences for human health. To meet these new challenges, the World Health Organization recommends reinforcing the adaptive capacity of health systems. One of the possible avenues in this respect is to promote awareness and knowledge translation in climatic health, at both the local and global scales. Within such perspective, two major themes have emerged in the field of public health research: 1) the development of advanced training adapted to 'global environment' change and to the specific needs of various groups of actors (doctors, nurses, public health practitioners, health care managers, public service managers, local communities, etc) and 2) the development of strategies for implementing research results and applying various types of evidence to the management of public health issues affected by climate change. Progress on these two fronts will depend on maximum innovation in transdisciplinary and transsectoral collaborations. The general purpose of this article is to present the program of a new research and learning chair designed for this double set of developmental objectives - a chair that emphasizes 'innoversity' (the dynamic relationship between innovation and diversity) and 'transfrontier ecolearning for adaptive actions'. The Écoapprentissages, santé mentale et climat collaborative research chair (University of Montreal and Quebec National Public Health Institute) based in Montreal is a center for 'transdisciplinary research' on the transfrontier knowledge-for-action that can aid adaptation of the public health sector, the public mental health sector, and the public service sector to climate change, as well as a center for complex collaborations on evidence-based climatic health 'training'. This program-focused article comprises two main sections. The first section presents the 'general' and 'specific contexts' in which the

  11. Innoversity in knowledge-for-action and adaptation to climate change: the first steps of an ‘evidence-based climatic health’ transfrontier training program

    PubMed Central

    Lapaige, Véronique; Essiembre, Hélène

    2010-01-01

    It has become increasingly clear to the international scientific community that climate change is real and has important consequences for human health. To meet these new challenges, the World Health Organization recommends reinforcing the adaptive capacity of health systems. One of the possible avenues in this respect is to promote awareness and knowledge translation in climatic health, at both the local and global scales. Within such perspective, two major themes have emerged in the field of public health research: 1) the development of advanced training adapted to ‘global environment’ change and to the specific needs of various groups of actors (doctors, nurses, public health practitioners, health care managers, public service managers, local communities, etc) and 2) the development of strategies for implementing research results and applying various types of evidence to the management of public health issues affected by climate change. Progress on these two fronts will depend on maximum innovation in transdisciplinary and transsectoral collaborations. The general purpose of this article is to present the program of a new research and learning chair designed for this double set of developmental objectives – a chair that emphasizes ‘innoversity’ (the dynamic relationship between innovation and diversity) and ‘transfrontier ecolearning for adaptive actions’. The Écoapprentissages, santé mentale et climat collaborative research chair (University of Montreal and Quebec National Public Health Institute) based in Montreal is a center for ‘transdisciplinary research’ on the transfrontier knowledge-for-action that can aid adaptation of the public health sector, the public mental health sector, and the public service sector to climate change, as well as a center for complex collaborations on evidence-based climatic health ‘training’. This program-focused article comprises two main sections. The first section presents the ‘general’ and

  12. Combined Protein A and size exclusion high performance liquid chromatography for the single-step measurement of mAb, aggregates and host cell proteins.

    PubMed

    Gjoka, Xhorxhi; Schofield, Mark; Cvetkovic, Aleksandar; Gantier, Rene

    2014-12-01

    Quantification of monoclonal antibody (mAb) monomer, mAb aggregates, and host cell proteins (HCPs) is critical for the optimization of the mAb production process. The present work describes a single high throughput analytical tool capable of tracking the concentration of mAb, mAb aggregate and HCPs in a growing cell culture batch. By combining two analytical HPLC methods, Protein A affinity and size-exclusion chromatography (SEC), it is possible to detect a relative increase or decrease in the concentration of all three entities simultaneously. A comparison of the combined Protein A-SEC assay to SEC alone was performed, demonstrating that it can be useful tool for the quantification of mAb monomer along with trending data for mAb aggregate and HCP. Furthermore, the study shows that the Protein A-SEC method is at least as accurate as other commonly used analytical methods such as ELISA and Bradford.

  13. Finite-Size Scaling of a First-Order Dynamical Phase Transition: Adaptive Population Dynamics and an Effective Model.

    PubMed

    Nemoto, Takahiro; Jack, Robert L; Lecomte, Vivien

    2017-03-17

    We analyze large deviations of the time-averaged activity in the one-dimensional Fredrickson-Andersen model, both numerically and analytically. The model exhibits a dynamical phase transition, which appears as a singularity in the large deviation function. We analyze the finite-size scaling of this phase transition numerically, by generalizing an existing cloning algorithm to include a multicanonical feedback control: this significantly improves the computational efficiency. Motivated by these numerical results, we formulate an effective theory for the model in the vicinity of the phase transition, which accounts quantitatively for the observed behavior. We discuss potential applications of the numerical method and the effective theory in a range of more general contexts.

  14. Finite-Size Scaling of a First-Order Dynamical Phase Transition: Adaptive Population Dynamics and an Effective Model

    NASA Astrophysics Data System (ADS)

    Nemoto, Takahiro; Jack, Robert L.; Lecomte, Vivien

    2017-03-01

    We analyze large deviations of the time-averaged activity in the one-dimensional Fredrickson-Andersen model, both numerically and analytically. The model exhibits a dynamical phase transition, which appears as a singularity in the large deviation function. We analyze the finite-size scaling of this phase transition numerically, by generalizing an existing cloning algorithm to include a multicanonical feedback control: this significantly improves the computational efficiency. Motivated by these numerical results, we formulate an effective theory for the model in the vicinity of the phase transition, which accounts quantitatively for the observed behavior. We discuss potential applications of the numerical method and the effective theory in a range of more general contexts.

  15. Adaptation of a cyanobacterium to a biochemically rich environment in experimental evolution as an initial step toward a chloroplast-like state.

    PubMed

    Hosoda, Kazufumi; Habuchi, Masumi; Suzuki, Shingo; Miyazaki, Mikako; Takikawa, Go; Sakurai, Takahiro; Kashiwagi, Akiko; Sueyoshi, Makoto; Matsumoto, Yusuke; Kiuchi, Ayako; Mori, Kotaro; Yomo, Tetsuya

    2014-01-01

    Chloroplasts originated from cyanobacteria through endosymbiosis. The original cyanobacterial endosymbiont evolved to adapt to the biochemically rich intracellular environment of the host cell while maintaining its photosynthetic function; however, no such process has been experimentally demonstrated. Here, we show the adaptation of a model cyanobacterium, Synechocystis sp. PCC 6803, to a biochemically rich environment by experimental evolution. Synechocystis sp. PCC 6803 does not grow in a biochemically rich, chemically defined medium because several amino acids are toxic to the cells at approximately 1 mM. We cultured the cyanobacteria in media with the toxic amino acids at 0.1 mM, then serially transferred the culture, gradually increasing the concentration of the toxic amino acids. The cells evolved to show approximately the same specific growth rate in media with 0 and 1 mM of the toxic amino acid in approximately 84 generations and evolved to grow faster in the media with 1 mM than in the media with 0 mM in approximately 181 generations. We did not detect a statistically significant decrease in the autotrophic growth of the evolved strain in an inorganic medium, indicating the maintenance of the photosynthetic function. Whole-genome resequencing revealed changes in the genes related to the cell membrane and the carboxysome. Moreover, we quantitatively analyzed the evolutionary changes by using simple mathematical models, which evaluated the evolution as an increase in the half-maximal inhibitory concentration (IC50) and estimated quantitative characteristics of the evolutionary process. Our results clearly demonstrate not only the potential of a model cyanobacterium to adapt to a biochemically rich environment without a significant decrease in photosynthetic function but also the properties of its evolutionary process, which sheds light of the evolution of chloroplasts at the initial stage.

  16. Exploring the size adaptability of the B ring binding zone of the colchicine site of tubulin with para-nitrogen substituted isocombretastatins.

    PubMed

    Jiménez, Carmen; Ellahioui, Younes; Álvarez, Raquel; Aramburu, Laura; Riesco, Alejandra; González, Myriam; Vicente, Alba; Dahdouh, Abdelaziz; Ibn Mansour, Ahmed; Jiménez, Carlos; Martín, Diego; Sarmiento, Rogelio G; Medarde, Manuel; Caballero, Esther; Peláez, Rafael

    2015-07-15

    We have synthesized and assayed dimethylaminophenyl, pyrrolidin-1-ylphenyl and carbazole containing phenstatins and isocombretastatins as analogues of the highly potent indoleisocombretastatins with extended or reduced ring sizes. This is an attempt to explore beyond the structural constraints of the X-ray crystal structures the zone of the colchicine site where the tropolone ring of colchicine binds to tubulin (zone 1). The isocombretastatins display up to 30 fold increased water solubility when compared with combretastatin A-4, potent inhibition of tubulin polymerization, and nanomolar cytotoxicities against several human cancer cell lines irrespective of the size of the B ring. On the other hand, substitutions ortho to the nitrogen cause an important reduction in potency. We have also shown that representative compounds inhibit autophagy. These results show that zone 1 can adapt to systems of different size as far as they stay in a common plane, but does not tolerate substituents protruding above or below it. These results can help in the understanding of the binding modes of structures with similar systems and in the design of new colchicine site ligands.

  17. PHOEBE - step by step manual

    NASA Astrophysics Data System (ADS)

    Zasche, P.

    2016-03-01

    An easy step-by-step manual of PHOEBE is presented. It should serve as a starting point for the first time users of PHOEBE analyzing the eclipsing binary light curve. It is demonstrated on one particular detached system also with the downloadable data and the whole procedure is described easily till the final trustworthy fit is being reached.

  18. Multiple stage miniature stepping motor

    DOEpatents

    Niven, William A.; Shikany, S. David; Shira, Michael L.

    1981-01-01

    A stepping motor comprising a plurality of stages which may be selectively activated to effect stepping movement of the motor, and which are mounted along a common rotor shaft to achieve considerable reduction in motor size and minimum diameter, whereby sequential activation of the stages results in successive rotor steps with direction being determined by the particular activating sequence followed.

  19. Analysis of the dynamics of adaptation to transgenic corn and crop rotation by western corn rootworm (Coleoptera: Chrysomelidae) using a daily time-step model.

    PubMed

    Crowder, D W; Onstad, D W; Cray, M E; Pierce, C M F; Hager, A G; Ratcliffe, S T; Steffey, K L

    2005-04-01

    Western corn rootworm, Diabrotica virgifera virgifera LeConte, has overcome crop rotation in several areas of the north central United States. The effectiveness of crop rotation for management of corn rootworm has begun to fail in many areas of the midwestern United States, thus new management strategies need to be developed to control rotation-resistant populations. Transgenic corn, Zea mays L., effective against western corn rootworm, may be the most effective new technology for control of this pest in areas with or without populations adapted to crop rotation. We expanded a simulation model of the population dynamics and genetics of the western corn rootworm for a landscape of corn; soybean, Glycine max (L.); and other crops to study the simultaneous development of resistance to both crop rotation and transgenic corn. Results indicate that planting transgenic corn to first-year cornfields is a robust strategy to prevent resistance to both crop rotation and transgenic corn in areas where rotation-resistant populations are currently a problem or may be a problem in the future. In these areas, planting transgenic corn only in continuous cornfields is not an effective strategy to prevent resistance to either trait. In areas without rotation-resistant populations, gene expression of the allele for resistance to transgenic corn, R, is the most important factor affecting the evolution of resistance. If R is recessive, resistance can be delayed longer than 15 yr. If R is dominant, resistance may be difficult to prevent. In a sensitivity analysis, results indicate that density dependence, rotational level in the landscape, and initial allele frequency are the three most important factors affecting the results.

  20. Newmark local time stepping on high-performance computing architectures

    NASA Astrophysics Data System (ADS)

    Rietmann, Max; Grote, Marcus; Peter, Daniel; Schenk, Olaf

    2017-04-01

    In multi-scale complex media, finite element meshes often require areas of local refinement, creating small elements that can dramatically reduce the global time-step for wave-propagation problems due to the CFL condition. Local time stepping (LTS) algorithms allow an explicit time-stepping scheme to adapt the time-step to the element size, allowing near-optimal time-steps everywhere in the mesh. We develop an efficient multilevel LTS-Newmark scheme and implement it in a widely used continuous finite element seismic wave-propagation package. In particular, we extend the standard LTS formulation with adaptations to continuous finite element methods that can be implemented very efficiently with very strong element-size contrasts (more than 100x). Capable of running on large CPU and GPU clusters, we present both synthetic validation examples and large scale, realistic application examples to demonstrate the performance and applicability of the method and implementation on thousands of CPU cores and hundreds of GPUs.

  1. Adaptive SPECT

    PubMed Central

    Barrett, Harrison H.; Furenlid, Lars R.; Freed, Melanie; Hesterman, Jacob Y.; Kupinski, Matthew A.; Clarkson, Eric; Whitaker, Meredith K.

    2008-01-01

    Adaptive imaging systems alter their data-acquisition configuration or protocol in response to the image information received. An adaptive pinhole single-photon emission computed tomography (SPECT) system might acquire an initial scout image to obtain preliminary information about the radiotracer distribution and then adjust the configuration or sizes of the pinholes, the magnifications, or the projection angles in order to improve performance. This paper briefly describes two small-animal SPECT systems that allow this flexibility and then presents a framework for evaluating adaptive systems in general, and adaptive SPECT systems in particular. The evaluation is in terms of the performance of linear observers on detection or estimation tasks. Expressions are derived for the ideal linear (Hotelling) observer and the ideal linear (Wiener) estimator with adaptive imaging. Detailed expressions for the performance figures of merit are given, and possible adaptation rules are discussed. PMID:18541485

  2. Hydrologic consistency analysed through modeling at multiple time steps: does hydrological model performance benefit from finer time step information?

    NASA Astrophysics Data System (ADS)

    Ficchi, Andrea; Perrin, Charles; Andréassian, Vazken

    2015-04-01

    We investigate the operational utility of fine time step hydro-climatic information using a large catchment data set. The originality of this data set lies in the availability of precipitation data from the 6-minute rain gauges of Météo-France, and in the size of the catchment set (217 French catchments in total). The rainfall-runoff model used (GR4) has been adapted to hourly and sub-hourly time steps (up to 6-minute) from the daily time step version (Perrin et al., 2003). The model is applied at different time steps ranging from 6-minute to 1 day (6-, 12-, 30-minute, 1-, 3-, 6-, 12-hour and 1 day) and the evolution of model performance for each catchment is evaluated at the daily time step by aggregation of model outputs. Three classes of behavior are found according to the trend of model performance as the time step becomes finer: (i) catchments presenting an improvement of model performance; (ii) catchments with a model performance insensitive to the time step; (iii) catchments for which the performance even deteriorates as the time step becomes finer. The reasons behind these different trends are investigated from a hydrological point of view, by relating the model sensitivity to data at finer time step to catchment descriptors. References: Perrin, C., C. Michel and V. Andréassian (2003), "Improvement of a parsimonious model for streamflow simulation", Journal of Hydrology, 279(1-4): 275-289.

  3. Evaluation of several two-step scoring functions based on linear interaction energy, effective ligand size, and empirical pair potentials for prediction of protein-ligand binding geometry and free energy.

    PubMed

    Rahaman, Obaidur; Estrada, Trilce P; Doren, Douglas J; Taufer, Michela; Brooks, Charles L; Armen, Roger S

    2011-09-26

    The performances of several two-step scoring approaches for molecular docking were assessed for their ability to predict binding geometries and free energies. Two new scoring functions designed for "step 2 discrimination" were proposed and compared to our CHARMM implementation of the linear interaction energy (LIE) approach using the Generalized-Born with Molecular Volume (GBMV) implicit solvation model. A scoring function S1 was proposed by considering only "interacting" ligand atoms as the "effective size" of the ligand and extended to an empirical regression-based pair potential S2. The S1 and S2 scoring schemes were trained and 5-fold cross-validated on a diverse set of 259 protein-ligand complexes from the Ligand Protein Database (LPDB). The regression-based parameters for S1 and S2 also demonstrated reasonable transferability in the CSARdock 2010 benchmark using a new data set (NRC HiQ) of diverse protein-ligand complexes. The ability of the scoring functions to accurately predict ligand geometry was evaluated by calculating the discriminative power (DP) of the scoring functions to identify native poses. The parameters for the LIE scoring function with the optimal discriminative power (DP) for geometry (step 1 discrimination) were found to be very similar to the best-fit parameters for binding free energy over a large number of protein-ligand complexes (step 2 discrimination). Reasonable performance of the scoring functions in enrichment of active compounds in four different protein target classes established that the parameters for S1 and S2 provided reasonable accuracy and transferability. Additional analysis was performed to definitively separate scoring function performance from molecular weight effects. This analysis included the prediction of ligand binding efficiencies for a subset of the CSARdock NRC HiQ data set where the number of ligand heavy atoms ranged from 17 to 35. This range of ligand heavy atoms is where improved accuracy of predicted ligand

  4. Local Climate Action Framework: A Step-by-Step Implementation Guide

    EPA Pesticide Factsheets

    This guide provides step-by-step guidance and resources for local governments to plan, implement, and evaluate climate, energy, and sustainability projects/programs to reduce greenhouse gas emissions and adapt to climate change impacts.

  5. Stepped nozzle

    DOEpatents

    Sutton, George P.

    1998-01-01

    An insert which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment.

  6. Stepped nozzle

    DOEpatents

    Sutton, G.P.

    1998-07-14

    An insert is described which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment. 5 figs.

  7. Effects of Particle Size and Adaptation Duration on the Digestible and Metabolizable Energy Contents and Digestibility of Various Chemical Constituents in Wheat for Finishing Pigs Determined by the Direct or Indirect Method.

    PubMed

    Fan, Yuanfang; Ma, Yongxi; Guo, Panpan; Yang, Yuyuan; Xia, Tian; Liu, Ling

    2016-08-19

    This experiment was conducted as a 3 × 2 × 2 factorial design to examine the effects of particle size (mean particle size of 331, 640 or 862 μm), evaluation method (direct vs. indirect method) and adaptation duration (7 or 26 days) on the energy content and the apparent total tract digestibility (ATTD) of various chemical components in wheat when fed to finishing pigs. Forty-two barrows (Duroc x Landrace x Yorkshire) with an initial body weight of 63.0 ± 0.8 kg were individually placed in metabolic cages and randomly allotted to 1 of 7 diets with 6 pigs fed each diet. For the indirect method, the pigs were fed either a corn-soybean meal based basal diet or diets in which 38.94% of the basal diet was substituted by wheat of the different particle sizes. In the direct method, the diets contained 97.34% wheat with the different particle sizes. For both the direct and indirect methods, the pigs were adapted to their diets for either 7 or 26 days. A reduction in particle size linearly increased the digestible (DE) and metabolizable energy (ME) contents as well as the ATTD of gross energy, crude protein, organic matter, ether extract (EE) and acid detergent fiber (ADF) (p<0.05), and had a trend to increase the ATTD of dry matter of wheat (p=0.084). The DE, ME contents and ATTD of gross energy, crud protein, dry matter and organic matter were higher (p<0.05) when determined by the direct method, but the ATTD of ADF, EE and neutral detergent fiber were higher when determined by the indirect method (p<0.05). Prolongation of the adaption duration decreased the ATTD of neutral detergent fiber (p<0.05) and had a trend to increase the ATTD of EE (P=0.061). There were no interactions between particle size and the duration of the adaptation duration. The ATTD of EE in wheat was influenced by a trend of interaction between method and adaptation duration (p=0.074). The ATTD of ADF and EE in wheat was influenced by an interaction between evaluation method and wheat particle size

  8. Adaptive Discontinuous Galerkin Approximation to Richards' Equation

    NASA Astrophysics Data System (ADS)

    Li, H.; Farthing, M. W.; Miller, C. T.

    2006-12-01

    Due to the occurrence of large gradients in fluid pressure as a function of space and time resulting from nonlinearities in closure relations, numerical solutions to Richards' equations are notoriously difficult for certain media properties and auxiliary conditions that occur routinely in describing physical systems of interest. These difficulties have motivated a substantial amount of work aimed at improving numerical approximations to this physically important and mathematically rich model. In this work, we build upon recent advances in temporal and spatial discretization methods by developing spatially and temporally adaptive solution approaches based upon the local discontinuous Galerkin method in space and a higher order backward difference method in time. Spatial step-size adaption, h adaption, approaches are evaluated and a so-called hp-adaption strategy is considered as well, which adjusts both the step size and the order of the approximation. Solution algorithms are advanced and performance is evaluated. The spatially and temporally adaptive approaches are shown to be robust and offer significant increases in computational efficiency compared to similar state-of-the-art methods that adapt in time alone. In addition, we extend the proposed methods to two dimensions and provide preliminary numerical results.

  9. Adaptive Cuckoo Search Algorithm for Unconstrained Optimization

    PubMed Central

    2014-01-01

    Modification of the intensification and diversification approaches in the recently developed cuckoo search algorithm (CSA) is performed. The alteration involves the implementation of adaptive step size adjustment strategy, and thus enabling faster convergence to the global optimal solutions. The feasibility of the proposed algorithm is validated against benchmark optimization functions, where the obtained results demonstrate a marked improvement over the standard CSA, in all the cases. PMID:25298971

  10. Adaptive cuckoo search algorithm for unconstrained optimization.

    PubMed

    Ong, Pauline

    2014-01-01

    Modification of the intensification and diversification approaches in the recently developed cuckoo search algorithm (CSA) is performed. The alteration involves the implementation of adaptive step size adjustment strategy, and thus enabling faster convergence to the global optimal solutions. The feasibility of the proposed algorithm is validated against benchmark optimization functions, where the obtained results demonstrate a marked improvement over the standard CSA, in all the cases.

  11. Micromachine Wedge Stepping Motor

    SciTech Connect

    Allen, J.J.; Schriner, H.K.

    1998-11-04

    A wedge stepping motor, which will index a mechanism, has been designed and fabricated in the surface rnicromachine SUMMiT process. This device has demonstrated the ability to index one gear tooth at a time with speeds up to 205 teeth/see. The wedge stepper motor has the following features, whi:h will be useful in a number of applications. o The ability to precisely position mechanical components. . Simple pulse signals can be used for operation. o Only 2 drive signals are requixed for operation. o Torque and precision capabilities increase with device size . The device to be indexed is restrained at all times by the wedge shaped tooth that is used for actuation. This paper will discuss the theory of operation and desi=m of the wedge stepping motor. The fabrication and testing of I he device will also be presented.

  12. Performance Analysis of Adaptive Volterra Filters in the Finite-Alphabet Input Case

    NASA Astrophysics Data System (ADS)

    Besbes, Hichem; Jaïdane, Mériem; Ezzine, Jelel

    2004-12-01

    This paper deals with the analysis of adaptive Volterra filters, driven by the LMS algorithm, in the finite-alphabet inputs case. A tailored approach for the input context is presented and used to analyze the behavior of this nonlinear adaptive filter. Complete and rigorous mean square analysis is provided without any constraining independence assumption. Exact transient and steady-state performances expressed in terms of critical step size, rate of transient decrease, optimal step size, excess mean square error in stationary mode, and tracking nonstationarities are deduced.

  13. A passive microfluidic system based on step emulsification allows the generation of libraries of nanoliter-sized droplets from microliter droplets of varying and known concentrations of a sample.

    PubMed

    Postek, W; Kaminski, T S; Garstecki, P

    2017-03-29

    We present a novel geometry of microfluidic channels that allows us to passively generate monodisperse emulsions of hundreds of droplets smaller than 1 nL from collections of larger (ca. 0.4 μL) mother droplets. We introduce a new microfluidic module for the generation of droplets via passive break-up at a step. The module alleviates a common problem in step emulsification with efficient removal of the droplets from the vicinity of the step. In our solution, the droplets are pushed away from the step by a continuous liquid that bypasses the mother droplets via specially engineered bypasses that lead to the step around the main channel. We show that the bypasses tighten the distribution of volume of daughter droplets and eliminate subpopulations of daughter droplets. Clearing away the just produced droplets from the vicinity of the step provides for similar conditions of break-up for every subsequent droplet and, consequently, leads to superior monodispersity of the generated emulsions. Importantly, this function is realized autonomously (passively) in a protocol in which only a sequence of large mother droplets is forced through the module. Our system features the advantage of step emulsification systems in that the volumes of the generated droplets depend very weakly on the rate of flow through the module - an increase in the flow rate by 300% causes only a slight increase of the average diameter of generated droplets by less than 5%. We combined our geometry with a simple T-junction and a simple trap-based microdroplet dilutor to produce a collection of libraries of droplets of gradually changing and known concentrations of a sample. The microfluidic system can be operated with only two syringe pumps set at constant rates of flow during the experiment.

  14. A Step-by-Step Guide to Personalize Learning

    ERIC Educational Resources Information Center

    Bray, Barbara; McClaskey, Kathleen

    2013-01-01

    It is known that every learner is unique and that one-size-fits-all instruction does not work for most. How can a classroom environment be created that gives each learner voice and choice? The co-founders of Personalize Learning, LLC, offer a detailed six-step approach. This article provides the background on what is and what is not Personalized…

  15. Adaptive Strategies for Materials Design using Uncertainties.

    PubMed

    Balachandran, Prasanna V; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-21

    We compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young's (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don't. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.

  16. Segmented Coil Fails In Steps

    NASA Technical Reports Server (NTRS)

    Stedman, Ronald S.

    1990-01-01

    Electromagnetic coil degrades in steps when faults occur, continues to operate at reduced level instead of failing catastrophically. Made in segments connected in series and separated by electrically insulating barriers. Fault does not damage adjacent components or create hazard. Used to control valves in such critical applications as cooling systems of power generators and chemical process equipment, where flammable liquids or gases handled. Also adapts to electrical control of motors.

  17. Evaluation of tropically-adapted straightbred and crossbred beef cattle: Heifer age and size at first conception and characteristics of their first calves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of this work were to estimate genetic effects for age and size at estimated time of first conception, and temperament in straightbred and crossbred heifers (n = 554) produced from Romosinuano, Brahman, and Angus cattle, and to evaluate first parturition performance of heifers, includi...

  18. Optimal timing of retinal scanning during dark adaptation, in the presence of fixation on a target: the role of pupil size dynamics.

    PubMed

    Gramatikov, Boris I; Irsch, Kristina; Guyton, David

    2014-01-01

    While validating our newly developed vision screener based on a double-pass retinal scanning system, we noticed that in all patients the signals from the retina were significantly higher when measurements were performed within a certain time interval referenced to the initial moment when the lights were dimmed and the test subject was asked to fixate on a target. This appeared to be most likely attributable to pupil size dynamics and triggered the present study, whose aim was to assess the pupillary “lights-off” response while fixating on a target in the presence of an accommodative effort. We found that pupil size increases in the first 60 to 70 s after turning off the room lights, and then it decreases toward the baseline in an exponential decay. Our results suggest that there is an optimal time window during which pupil size is expected to be maximal, that is during the second minute after dimming the room lights. During this time, window retinal diagnostic instruments based on double-pass measurement technology should deliver an optimal signal-to-noise ratio. We also propose a mathematical model that can be used to approximate the behavior of the normalized pupil size.

  19. Optimal timing of retinal scanning during dark adaptation, in the presence of fixation on a target: the role of pupil size dynamics

    NASA Astrophysics Data System (ADS)

    Gramatikov, Boris I.; Irsch, Kristina; Guyton, David

    2014-10-01

    While validating our newly developed vision screener based on a double-pass retinal scanning system, we noticed that in all patients the signals from the retina were significantly higher when measurements were performed within a certain time interval referenced to the initial moment when the lights were dimmed and the test subject was asked to fixate on a target. This appeared to be most likely attributable to pupil size dynamics and triggered the present study, whose aim was to assess the pupillary "lights-off" response while fixating on a target in the presence of an accommodative effort. We found that pupil size increases in the first 60 to 70 s after turning off the room lights, and then it decreases toward the baseline in an exponential decay. Our results suggest that there is an optimal time window during which pupil size is expected to be maximal, that is during the second minute after dimming the room lights. During this time, window retinal diagnostic instruments based on double-pass measurement technology should deliver an optimal signal-to-noise ratio. We also propose a mathematical model that can be used to approximate the behavior of the normalized pupil size.

  20. TH-E-BRE-11: Adaptive-Beamlet Based Finite Size Pencil Beam (AB-FSPB) Dose Calculation Algorithm for Independent Verification of IMRT and VMAT

    SciTech Connect

    Park, C; Arhjoul, L; Yan, G; Lu, B; Li, J; Liu, C

    2014-06-15

    Purpose: In current IMRT and VMAT settings, the use of sophisticated dose calculation procedure is inevitable in order to account complex treatment field created by MLCs. As a consequence, independent volumetric dose verification procedure is time consuming which affect the efficiency of clinical workflow. In this study, the authors present an efficient Pencil Beam based dose calculation algorithm that minimizes the computational procedure while preserving the accuracy. Methods: The computational time of Finite Size Pencil Beam (FSPB) algorithm is proportional to the number of infinitesimal identical beamlets that constitute the arbitrary field shape. In AB-FSPB, the dose distribution from each beamlet is mathematically modelled such that the sizes of beamlets to represent arbitrary field shape are no longer needed to be infinitesimal nor identical. In consequence, it is possible to represent arbitrary field shape with combinations of different sized and minimal number of beamlets. Results: On comparing FSPB with AB-FSPB, the complexity of the algorithm has been reduced significantly. For 25 by 25 cm2 squared shaped field, 1 beamlet of 25 by 25 cm2 was sufficient to calculate dose in AB-FSPB, whereas in conventional FSPB, minimum 2500 beamlets of 0.5 by 0.5 cm2 size were needed to calculate dose that was comparable to the Result computed from Treatment Planning System (TPS). The algorithm was also found to be GPU compatible to maximize its computational speed. On calculating 3D dose of IMRT (∼30 control points) and VMAT plan (∼90 control points) with grid size 2.0 mm (200 by 200 by 200), the dose could be computed within 3∼5 and 10∼15 seconds. Conclusion: Authors have developed an efficient Pencil Beam type dose calculation algorithm called AB-FSPB. The fast computation nature along with GPU compatibility has shown performance better than conventional FSPB. This completely enables the implantation of AB-FSPB in the clinical environment for independent

  1. Adaptive EZW coding using a rate-distortion criterion

    NASA Astrophysics Data System (ADS)

    Yin, Che-Yi

    2001-07-01

    This work presents a new method that improves on the EZW image coding algorithm. The standard EZW image coder uses a uniform quantizer with a threshold (deadzone) that is identical in all subbands. The quantization step sizes are not optimized under the rate-distortion sense. We modify the EZW by applying the Lagrange multiplier to search for the best step size for each subband and allocate the bit rate for each subband accordingly. Then we implement the adaptive EZW codec to code the wavelet coefficients. Two coding environments, independent and dependent, are considered for the optimization process. The proposed image coder retains all the good features of the EZW, namely, embedded coding, progressive transmission, order of the important bits, and enhances it through the rate-distortion optimization with respect to the step sizes.

  2. Piezoelectric step-motion actuator

    DOEpatents

    Mentesana; Charles P.

    2006-10-10

    A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

  3. A Feedfordward Adaptive Controller to Reduce the Imaging Time of Large-Sized Biological Samples with a SPM-Based Multiprobe Station

    PubMed Central

    Otero, Jorge; Guerrero, Hector; Gonzalez, Laura; Puig-Vidal, Manel

    2012-01-01

    The time required to image large samples is an important limiting factor in SPM-based systems. In multiprobe setups, especially when working with biological samples, this drawback can make impossible to conduct certain experiments. In this work, we present a feedfordward controller based on bang-bang and adaptive controls. The controls are based in the difference between the maximum speeds that can be used for imaging depending on the flatness of the sample zone. Topographic images of Escherichia coli bacteria samples were acquired using the implemented controllers. Results show that to go faster in the flat zones, rather than using a constant scanning speed for the whole image, speeds up the imaging process of large samples by up to a 4× factor. PMID:22368491

  4. Gestalt and Other Strategies for Exploring Dreams through a Step-by-Step Approach.

    ERIC Educational Resources Information Center

    France, M. Honore; Allen, G. Edward

    1993-01-01

    The Gestalt dream approach is a practical way to explore personal issues. This article demonstrates how dream work can be adapted by counselors to focus clients to direct forms of personal exploration. A four-step strategy is described. (Authors)

  5. Unzipping mechanism of the double-stranded DNA unwinding by a hexameric helicase: quantitative analysis of the rate of the dsDNA unwinding, processivity and kinetic step-size of the Escherichia coli DnaB helicase using rapid quench-flow method.

    PubMed

    Galletto, Roberto; Jezewska, Maria J; Bujalowski, Wlodzimierz

    2004-10-08

    Kinetics of the double-stranded (ds) DNA unwinding by the Escherichia coli replicative helicase DnaB protein has been examined under single-turnover conditions using the chemical quench-flow technique. The unwinding reaction proceeds through an initial conformational transition followed by the unwinding catalytic steps and the release of the single-stranded (ss) DNA. Analyses of the reaction as a function of the number of base-pairs in the dsDNA reveal that the number of catalytic steps is not strictly proportional to the length of the dsDNA. As the helicase approaches the end of the substrate, the remaining approximately 11 bp of the DNA melts without catalytic participation of the enzyme. The kinetic step-size of the DnaB helicase, i.e. the number of the base-pairs unwound in a single catalytic step is only 1.4(+/- 0.2). The low value of the step-size indicates that the helicase unwinds a single base-pair in a single catalytic step. Thus, the DnaB helicase unzips the dsDNA in a reverse process to the zipping mechanism of the non-enzymatic double helix formation. The protein is a fast helicase that at 25 degrees C unwinds approximately 291 bp/s, much faster than previously thought, and the unwinding rate can be much higher at higher temperatures. However, the ATP-state of the enzyme has an increased dissociation rate, resulting in only a moderate unwinding processivity, P = 0.89(+/- 0.03), little dependent on the temperature. The conformational transition of the DnaB helicase-DNA complex, preceding the unwinding, is an intrinsic transition of the enzyme from the stationary conformation to the ATP-state of the helicase.

  6. Adaptation Criteria for the Personalised Delivery of Learning Materials: A Multi-Stage Empirical Investigation

    ERIC Educational Resources Information Center

    Thalmann, Stefan

    2014-01-01

    Personalised e-Learning represents a major step-change from the one-size-fits-all approach of traditional learning platforms to a more customised and interactive provision of learning materials. Adaptive learning can support the learning process by tailoring learning materials to individual needs. However, this requires the initial preparation of…

  7. Step-Growth Polymerization.

    ERIC Educational Resources Information Center

    Stille, J. K.

    1981-01-01

    Following a comparison of chain-growth and step-growth polymerization, focuses on the latter process by describing requirements for high molecular weight, step-growth polymerization kinetics, synthesis and molecular weight distribution of some linear step-growth polymers, and three-dimensional network step-growth polymers. (JN)

  8. Stepping motor controller

    DOEpatents

    Bourret, Steven C.; Swansen, James E.

    1984-01-01

    A stepping motor is microprocessingly controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  9. Stepping motor controller

    DOEpatents

    Bourret, S.C.; Swansen, J.E.

    1982-07-02

    A stepping motor is microprocessor controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  10. RETRACTED: Size-controlled spherical polymer nanoparticles: synthesis with tandem acoustic emulsification followed by soap-free emulsion polymerization and one-step fabrication of colloidal crystal films of various colors.

    PubMed

    Hirai, Yuki; Nakabayashi, Koji; Kojima, Maya; Atobe, Mahito

    2014-11-01

    We have developed a novel synthesis method for size-controlled polymer nanoparticles using soap-free emulsion polymerization. This new synthetic method involves sequential ultrasonic irradiation (20kHz→500kHz→1.6MHz→2.4MHz) for acoustic emulsification of a water-insoluble monomer such as methylmethacrylate (MMA) in an aqueous medium, followed by emulsion polymerization in the obtained solution without using any surfactants. The sequential ultrasonication (tandem acoustic emulsification) could provide a clear and stable emulsified solution containing monomer droplets with relatively narrow size distribution in the nanometer range. The subsequent polymerization in this solution yielded size-controlled polymethylmethacrylate (PMMA) nanoparticles and monodisperse PMMA nanoparticles of different sizes. Furthermore, colloidal crystal films could be easily prepared from the as-polymerized nanoparticle solution using the fluidic-cell method. Moreover, we succeeded to modify the structural color of colloidal crystal films by the addition of a small amount of organic solvent to the as-polymerized nanoparticle solution for the fluidic-cell method.

  11. Evaluation of Several Two-Step Scoring Functions Based on Linear Interaction Energy, Effective Ligand Size, and Empirical Pair Potentials for Prediction of Protein-Ligand Binding Geometry and Free Energy

    PubMed Central

    Rahaman, Obaidur; Estrada, Trilce P.; Doren, Douglas J.; Taufer, Michela; Brooks, Charles L.; Armen, Roger S.

    2011-01-01

    The performance of several two-step scoring approaches for molecular docking were assessed for their ability to predict binding geometries and free energies. Two new scoring functions designed for “step 2 discrimination” were proposed and compared to our CHARMM implementation of the linear interaction energy (LIE) approach using the Generalized-Born with Molecular Volume (GBMV) implicit solvation model. A scoring function S1 was proposed by considering only “interacting” ligand atoms as the “effective size” of the ligand, and extended to an empirical regression-based pair potential S2. The S1 and S2 scoring schemes were trained and five-fold cross validated on a diverse set of 259 protein-ligand complexes from the Ligand Protein Database (LPDB). The regression-based parameters for S1 and S2 also demonstrated reasonable transferability in the CSARdock 2010 benchmark using a new dataset (NRC HiQ) of diverse protein-ligand complexes. The ability of the scoring functions to accurately predict ligand geometry was evaluated by calculating the discriminative power (DP) of the scoring functions to identify native poses. The parameters for the LIE scoring function with the optimal discriminative power (DP) for geometry (step 1 discrimination) were found to be very similar to the best-fit parameters for binding free energy over a large number of protein-ligand complexes (step 2 discrimination). Reasonable performance of the scoring functions in enrichment of active compounds in four different protein target classes established that the parameters for S1 and S2 provided reasonable accuracy and transferability. Additional analysis was performed to definitively separate scoring function performance from molecular weight effects. This analysis included the prediction of ligand binding efficiencies for a subset of the CSARdock NRC HiQ dataset where the number of ligand heavy atoms ranged from 17 to 35. This range of ligand heavy atoms is where improved accuracy of

  12. Simple and Inexpensive CD-ROM Networking: A Step-by-Step Approach.

    ERIC Educational Resources Information Center

    Cain, Mark

    1993-01-01

    Describes a low-cost, upgradeable, CD-ROM network and gives a step-by-step description of the installation process, including inventorying assets, learning about network components, selecting a network, installing adapter boards, attaching cabling, installing software, testing, configuring the server, installing search software, installing a menu,…

  13. A Step by Step Guide for Planning a Japanese Cultural Festival.

    ERIC Educational Resources Information Center

    Murphy, Carole

    Teachers at all academic levels can adapt the design and content of the sixth grade Japanese cultural festival detailed in this learning packet. Material is divided into 2 sections. Section 1 provides a step-by-step guide to planning and conducting the festival. These instructions, based on 5 years of experience, include a detailed planning…

  14. Adaptive Optics Imaging of the Circumbinary Disk around the T Tauri Binary UY Aurigae: Estimates of the Binary Mass and Circumbinary Dust Grain Size Distribution

    NASA Astrophysics Data System (ADS)

    Close, L. M.; Dutrey, A.; Roddier, F.; Guilloteau, S.; Roddier, C.; Northcott, M.; Ménard, F.; Duvert, G.; Graves, J. E.; Potter, D.

    1998-05-01

    We have obtained high-resolution (FWHM = 0.15") deep images of the UY Aur binary at J, H, and K' with the University of Hawaii adaptive optics instrument. We clearly detect an R ~ 500 AU circumbinary disk discovered with millimeter interferometry, making UY Aur the second young binary with a confirmed circumbinary disk. It appears that the disk is inclined ~42° from face on. We find that the near side of the disk is brighter than the far side by factors of 2.6, 2.7, and 6.5 times at K', H, and J, respectively. The original GG Tau circumbinary disk has been reexamined and is found to have similar flux ratios of 1.5, 2.6, and 3.6 at K', H, and J, respectively. A realistic power-law distribution (p = 4.7) of spherical dust aggregates (composed of silicates, amorphous carbon, and graphite) that reproduces the observed ISM extinction curve also predicts these observed flux ratios from Mie scattering theory. We find the observed preference of forward-scattering over back-scattering is well fitted (global χ2 minimization) by Mie scattering off particles in the range amin = 0.03 μm to amax = 0.5-0.6 μm. The existence of a significant population of grain radii larger than 0.6 μm is not supported by the scattering observations. Based on the observed disk inclination we derive an orbit for UY Aur where the mass for the binary is 1.6+0.47-0.67 M⊙. Based on the observed K7 and M0 spectral types for UY Aur A and B, accretion disk models for the inner disks around the central stars were constructed. The models suggest that small (lower limit R ~ 5-10 AU) inner disks exist around B and A. It appears that B is accreting ~5 times faster than A, and that both inner disks may be exhausted in ~102-103 yr without replenishment from the outer circumbinary disk. Our images suggest that these inner disks may indeed be resupplied with material through thin streamers of material that penetrate inside the circumbinary disk. Currently it appears that such a streamer may be a close to UY

  15. Physiological adaptations to reproduction. I. Experimentally increasing litter size enhances aspects of antioxidant defence but does not cause oxidative damage in mice.

    PubMed

    Garratt, Michael; Pichaud, Nicolas; King, Edith D Aloise; Brooks, Robert C

    2013-08-01

    Life history theory suggests that investment in reproduction can trade off against growth, longevity and both reproduction and performance later in life. One possible reason for this trade-off is that reproduction directly causes somatic damage. Oxidative stress, an overproduction of reactive oxygen species in relation to cellular defences, can correlate with reproductive investment and has been implicated as a pathway leading to senescence. This has led to the suggestion that this aspect of physiology could be an important mechanism underlying the trade-off between reproduction and lifespan. We manipulated female reproductive investment to test whether oxidative stress increases with reproduction in mice. Each female's pups were cross-fostered to produce litters of either two or eight, representing low and high levels of reproductive investment for wild mice. No differences were observed between reproductive groups at peak lactation for several markers of oxidative stress in the heart and gastrocnemius muscle. Surprisingly, oxidative damage to proteins was lower in the livers of females with a litter size of eight than in females with two pups or non-reproductive control females. While protein oxidation decreased, activity levels of the antioxidant enzyme superoxide dismutase increased in the liver, suggesting this may be one pathway used to protect against oxidative stress. Our results highlight the need for caution when interpreting correlative relationships and suggest that oxidative stress does not increase with enhanced reproductive effort during lactation.

  16. 2-Step IMAT and 2-Step IMRT in three dimensions

    SciTech Connect

    Bratengeier, Klaus

    2005-12-15

    In two dimensions, 2-Step Intensity Modulated Arc Therapy (2-Step IMAT) and 2-Step Intensity Modulated Radiation Therapy (IMRT) were shown to be powerful methods for the optimization of plans with organs at risk (OAR) (partially) surrounded by a target volume (PTV). In three dimensions, some additional boundary conditions have to be considered to establish 2-Step IMAT as an optimization method. A further aim was to create rules for ad hoc adaptations of an IMRT plan to a daily changing PTV-OAR constellation. As a test model, a cylindrically symmetric PTV-OAR combination was used. The centrally placed OAR can adapt arbitrary diameters with different gap widths toward the PTV. Along the rotation axis the OAR diameter can vary, the OAR can even vanish at some axis positions, leaving a circular PTV. The width and weight of the second segment were the free parameters to optimize. The objective function f to minimize was the root of the integral of the squared difference of the dose in the target volume and a reference dose. For the problem, two local minima exist. Therefore, as a secondary criteria, the magnitude of hot and cold spots were taken into account. As a result, the solution with a larger segment width was recommended. From plane to plane for varying radii of PTV and OAR and for different gaps between them, different sets of weights and widths were optimal. Because only one weight for one segment shall be used for all planes (respectively leaf pairs), a strategy for complex three-dimensional (3-D) cases was established to choose a global weight. In a second step, a suitable segment width was chosen, minimizing f for this global weight. The concept was demonstrated in a planning study for a cylindrically symmetric example with a large range of different radii of an OAR along the patient axis. The method is discussed for some classes of tumor/organ at risk combinations. Noncylindrically symmetric cases were treated exemplarily. The product of width and weight of

  17. Step by Step: Avoiding Spiritual Bypass in 12-Step Work

    ERIC Educational Resources Information Center

    Cashwell, Craig S.; Clarke, Philip B.; Graves, Elizabeth G.

    2009-01-01

    With spirituality as a cornerstone, 12-step groups serve a vital role in the recovery community. It is important for counselors to be mindful, however, of the potential for clients to be in spiritual bypass, which likely will undermine the recovery process.

  18. Smoothing out step changes of LMP

    SciTech Connect

    Li, Fangxing

    2008-08-15

    The locational marginal pricing methodology may lead to a step change when system load grows, creating higher financial risk, especially for small and medium-sized market participants. A proposed continuous LMP method is a straightforward solution to eliminate these step changes when load grows. (author)

  19. Detection of Steps in Single Molecule Data

    PubMed Central

    Aggarwal, Tanuj; Materassi, Donatello; Davison, Robert; Hays, Thomas; Salapaka, Murti

    2013-01-01

    Over the past few decades, single molecule investigations employing optical tweezers, AFM and TIRF microscopy have revealed that molecular behaviors are typically characterized by discrete steps or events that follow changes in protein conformation. These events, that manifest as steps or jumps, are short-lived transitions between otherwise more stable molecular states. A major limiting factor in determining the size and timing of the steps is the noise introduced by the measurement system. To address this impediment to the analysis of single molecule behaviors, step detection algorithms incorporate large records of data and provide objective analysis. However, existing algorithms are mostly based on heuristics that are not reliable and lack objectivity. Most of these step detection methods require the user to supply parameters that inform the search for steps. They work well, only when the signal to noise ratio (SNR) is high and stepping speed is low. In this report, we have developed a novel step detection method that performs an objective analysis on the data without input parameters, and based only on the noise statistics. The noise levels and characteristics can be estimated from the data providing reliable results for much smaller SNR and higher stepping speeds. An iterative learning process drives the optimization of step-size distributions for data that has unimodal step-size distribution, and produces extremely low false positive outcomes and high accuracy in finding true steps. Our novel methodology, also uniquely incorporates compensation for the smoothing affects of probe dynamics. A mechanical measurement probe typically takes a finite time to respond to step changes, and when steps occur faster than the probe response time, the sharp step transitions are smoothed out and can obscure the step events. To address probe dynamics we accept a model for the dynamic behavior of the probe and invert it to reveal the steps. No other existing method addresses

  20. Space-Time Adaptive Solution of Richards' Equation

    NASA Astrophysics Data System (ADS)

    Abhishek, C.; Miller, C. T.; Farthing, M. W.

    2003-12-01

    Efficient, robust simulation of groundwater flow in the unsaturated zone remains computationally expensive, especially for problems characterized by sharp fronts in both space and time. Standard approaches that employ uniform spatial and temporal discretizations for the numerical solution of these problems lead to inefficient and expensive simulations. In this work, we solve Richards' equation using adaptive methods in both space and time. Spatial adaption is based upon a coarse grid solve and gradient-based error indicators, while the spatial step size is adjusted using a fixed-order approximation. Temporal adaption is accomplished using variable-order, variable-step-size approximations based upon the backward difference formulas up to fifth order. Since the advantages of similar adaptive methods in time are now established, we evaluate our method by comparison with a uniform spatial discretization that is adaptive in time for four different test problems. The numerical results demonstrate that the proposed method provides a robust and efficient alternative to standard approaches for simulating variably saturated flow.

  1. One-step microlithography

    NASA Astrophysics Data System (ADS)

    Kahlen, Franz-Josef; Sankaranarayanan, Srikanth; Kar, Aravinda

    1997-09-01

    Subject of this investigation is a one-step rapid machining process to create miniaturized 3D parts, using the original sample material. An experimental setup where metal powder is fed to the laser beam-material interaction region has been built. The powder is melted and forms planar, 2D geometries as the substrate is moved under the laser beam in XY- direction. After completing the geometry in the plane, the substrate is displaced in Z-direction, and a new layer of material is placed on top of the just completed deposit. By continuous repetition of this process, 3D parts wee created. In particular, the impact of the focal spot size of the high power laser beam on the smallest achievable structures was investigated. At a translation speed of 51 mm/s a minimum material thickness of 590 micrometers was achieved. Also, it was shown that a small Z-displacement has a negligible influence on the continuity of the material deposition over this power range. A high power CO2 laser was used as energy source, the material powder under investigation was stainless steel SS304L. Helium was used as shield gas at a flow rate of 15 1/min. The incident CO2 laser beam power was varied between 300 W and 400 W, with the laser beam intensity distribute in a donut mode. The laser beam was focused to a focal diameter of 600 (Mu) m.

  2. A Step Circuit Program.

    ERIC Educational Resources Information Center

    Herman, Susan

    1995-01-01

    Aerobics instructors can use step aerobics to motivate students. One creative method is to add the step to the circuit workout. By incorporating the step, aerobic instructors can accommodate various fitness levels. The article explains necessary equipment and procedures, describing sample stations for cardiorespiratory fitness, muscular strength,…

  3. An evaluation of temporally adaptive transformation approaches for solving Richards' equation

    NASA Astrophysics Data System (ADS)

    Williams, Glenn A.; Miller, Cass T.

    Developing robust and efficient numerical solution methods for Richards' equation (RE) continues to be a challenge for certain problems. We consider such a problem here: infiltration into unsaturated porous media initially at static conditions for uniform and non-uniform pore size media. For ponded boundary conditions, a sharp infiltration front results, which propagates through the media. We evaluate the resultant solution method for robustness and efficiency using combinations of variable transformation and adaptive time-stepping methods. Transformation methods introduce a change of variable that results in a smoother solution, which is more amenable to efficient numerical solution. We use adaptive time-stepping methods to adjust the time-step size, and in some cases the order of the solution method, to meet a constraint on nonlinear solution convergence properties or a solution error criterion. Results for three test problems showed that adaptive time-stepping methods provided robust solutions; in most cases transforming the dependent variable led to more efficient solutions than untransformed approaches, especially as the pore-size uniformity increased; and the higher-order adaptive time integration method was robust and the most efficient method evaluated.

  4. Flipping Adapters for Space Launch System

    NASA Video Gallery

    The structural test article adapter is flipped at Marshall testing facility Building 4705. The turnover is an important step in finishing the machining work on the adapter, which will undergo tests...

  5. Human heat adaptation.

    PubMed

    Taylor, Nigel A S

    2014-01-01

    In this overview, human morphological and functional adaptations during naturally and artificially induced heat adaptation are explored. Through discussions of adaptation theory and practice, a theoretical basis is constructed for evaluating heat adaptation. It will be argued that some adaptations are specific to the treatment used, while others are generalized. Regarding ethnic differences in heat tolerance, the case is put that reported differences in heat tolerance are not due to natural selection, but can be explained on the basis of variations in adaptation opportunity. These concepts are expanded to illustrate how traditional heat adaptation and acclimatization represent forms of habituation, and thermal clamping (controlled hyperthermia) is proposed as a superior model for mechanistic research. Indeed, this technique has led to questioning the perceived wisdom of body-fluid changes, such as the expansion and subsequent decay of plasma volume, and sudomotor function, including sweat habituation and redistribution. Throughout, this contribution was aimed at taking another step toward understanding the phenomenon of heat adaptation and stimulating future research. In this regard, research questions are posed concerning the influence that variations in morphological configuration may exert upon adaptation, the determinants of postexercise plasma volume recovery, and the physiological mechanisms that modify the cholinergic sensitivity of sweat glands, and changes in basal metabolic rate and body core temperature following adaptation.

  6. Exploiting Adaptive Optics with Deformable Secondary Mirrors

    DTIC Science & Technology

    2007-03-08

    progress in tomographic wavefront sensing and altitude conjugated adaptive correction, and is a critical step forward for adaptive optics for future large...geostationary satellites, captured at the 6.5 m MMT telescope, using the deformable secondary adaptive optics system....new technology to the unique development of deformable secondary mirrors pioneered at the University of Arizona’s Center for Astronomical Adaptive

  7. Details for Manuscript Number SSM-D-06-00377R1 “Targeted Ethnography as a Critical Step to Inform Cultural Adaptations of HIV Prevention Interventions for Adults with Severe Mental Illness.”

    PubMed Central

    Gonzalez, M. Alfredo; McKinnon, Karen; Elkington, Katherine S; Pinto, Diana; Mann, Claudio Gruber; Mattos, Paulo E

    2007-01-01

    As in other countries worldwide, adults with severe mental illness (SMI) in Brazil are disproportionately infected with HIV relative to the general population. Brazilian psychiatric facilities lack tested HIV prevention interventions. To adapt existing interventions, developed only in the U.S., we conducted targeted ethnography with adults with SMI and staff from two psychiatric institutions in Brazil. We sought to characterize individual, institutional, and interpersonal factors that may affect HIV risk behavior in this population. We conducted 350 hours of ethnographic field observations in two mental health service settings in Rio de Janeiro, and 9 focus groups (n = 72) and 16 key-informant interviews with patients and staff in these settings. Data comprised field notes and audiotapes of all exchanges, which were transcribed, coded, and systematically analyzed. The ethnography characterized the institutional culture and identified: 1) patients’ risk behaviors; 2) the institutional setting; 3) intervention content; and 4) intervention format and delivery strategies. Targeted ethnography also illuminated broader contextual issues for development and implementation of HIV prevention interventions for adults with SMI in Brazil, including an institutional culture that did not systematically address patients’ sexual behavior, sexual health, or HIV sexual risk, yet strongly impacted the structure of patients’ sexual networks. Further, ethnography identified the Brazilian concept of “social responsibility” as important to prevention work with psychiatric patients. Targeted ethnography with adults with SMI and institutional staff provided information critical to the adaptation of tested U.S. HIV prevention interventions from the US for Brazilians with SMI. PMID:17475382

  8. Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei XVI: A 13 Year Study of Spectral Variability in NGC 5548

    NASA Technical Reports Server (NTRS)

    Peterson, B. M.; Berlind, P.; Bertram, R.; Bischoff, K.; Bochkarev, N. G.; Burenkov, A. N.; Calkins, M.; Carrasco, L.; Chavushyan, V. H.

    2002-01-01

    We present the final installment of an intensive 13 year study of variations of the optical continuum and broad H beta emission line in the Seyfert 1 galaxy NGC 5548. The database consists of 1530 optical continuum measurements and 1248 H beta measurements. The H beta variations follow the continuum variations closely, with a typical time delay of about 20 days. However, a year-by-year analysis shows that the magnitude of emission-line time delay is correlated with the mean continuum flux. We argue that the data are consistent with the simple model prediction between the size of the broad-line region and the ionizing luminosity, r is proportional to L(sup 1/2)(sub ion). Moreover, the apparently linear nature of the correlation between the H beta response time and the nonstellar optical continuum F(sub opt) arises as a consequence of the changing shape of the continuum as it varies, specifically F(sub opt) is proportional to F(sup 0.56)(sub UV).

  9. Small RNA Library Preparation Method for Next-Generation Sequencing Using Chemical Modifications to Prevent Adapter Dimer Formation.

    PubMed

    Shore, Sabrina; Henderson, Jordana M; Lebedev, Alexandre; Salcedo, Michelle P; Zon, Gerald; McCaffrey, Anton P; Paul, Natasha; Hogrefe, Richard I

    2016-01-01

    For most sample types, the automation of RNA and DNA sample preparation workflows enables high throughput next-generation sequencing (NGS) library preparation. Greater adoption of small RNA (sRNA) sequencing has been hindered by high sample input requirements and inherent ligation side products formed during library preparation. These side products, known as adapter dimer, are very similar in size to the tagged library. Most sRNA library preparation strategies thus employ a gel purification step to isolate tagged library from adapter dimer contaminants. At very low sample inputs, adapter dimer side products dominate the reaction and limit the sensitivity of this technique. Here we address the need for improved specificity of sRNA library preparation workflows with a novel library preparation approach that uses modified adapters to suppress adapter dimer formation. This workflow allows for lower sample inputs and elimination of the gel purification step, which in turn allows for an automatable sRNA library preparation protocol.

  10. A study on a micro-stepping drive system for space pointing platform

    NASA Astrophysics Data System (ADS)

    Yang, Shuang; Li, Bao-quan; Zhang, Xin

    2011-08-01

    Along with the continuous development of the research in the space exploration field, the precision rotation control system is widely utilized in a lot of payloads of the satellites. It is stepping motor cooperating with reduction gear wheel to accomplish the precision rotation in some pointing platforms of the camera used in the satellite. By contrast with that, the approach of this paper could precisely control the rotation angle of the stepping motor without using reduction gear wheel. Therefore, the size and the height of the instrument would be reduced base on simplifying the structural design. Moreover, it reduces the cost to some extent. In this paper, it is adopted that the digital signal processor (DSP) controller and bipolar constant current motor drive circuit UC3717 to make a high performance, high subdivision, miniature control system come true, which is used to drive two-phase hybrid stepping motor. The methods are applied by the driver system that sine cosine micro stepping and constant current chopper drive with a fixed chopper period. The driver system also supplies the functions that involve subdivision selection, clockwise rotation or counter clockwise rotation control, and over current or over voltage or under voltage or overload protection, and so on. The description in this paper also includes the total schematic design, the approach to get current table in different subdivision levels, the current control method in hybrid stepping motor, the way to reduce electro- magnetic interference (EMI) of the hybrid stepping motor. And the total schematic design contains the DSP controller, the communication interface of the driver system, the design of power driving circuit, the interface circuit between the electrical sources, the constant current chopper drive circuit for the two-phase hybrid stepping motor. At last, it is verified by some experimental investigations that the control system not only has miniature size, simplified system design

  11. Adapted Canoeing for the Handicapped.

    ERIC Educational Resources Information Center

    Frith, Greg H.; Warren, L. D.

    1984-01-01

    Safety as well as instructional recommendations are offered for adapting canoeing as a recreationial activity for handicapped students. Major steps of the instructional program feature orientation to the water and canoe, entry and exit techinques, and mobility procedures. (CL)

  12. Golgi-Cox Staining Step by Step

    PubMed Central

    Zaqout, Sami; Kaindl, Angela M.

    2016-01-01

    Golgi staining remains a key method to study neuronal morphology in vivo. Since most protocols delineating modifications of the original staining method lack details on critical steps, establishing this method in a laboratory can be time-consuming and frustrating. Here, we describe the Golgi-Cox staining in such detail that should turn the staining into an easily feasible method for all scientists working in the neuroscience field. PMID:27065817

  13. Link Dependent Adaptive Radio Simulation

    DTIC Science & Technology

    2014-06-01

    14. ABSTRACT This paper shows the optimized Link Dependent Adaptive Radio (LDAR) using the variable QAM OFDM modulation size which adapts to channel...bit error rate (BER), Orthogonal Frequency Division Multiplexing ( OFDM ) 16. SECURITY CLASSIFICATION OF: Unclassified 17. LIMITATION OF ABSTRACT...using the variable QAM OFDM modulation size which adapts to channel conditions. The LDAR enhanced performance is illustrated by use of a flight path

  14. WAKES: Wavelet Adaptive Kinetic Evolution Solvers

    NASA Astrophysics Data System (ADS)

    Mardirian, Marine; Afeyan, Bedros; Larson, David

    2016-10-01

    We are developing a general capability to adaptively solve phase space evolution equations mixing particle and continuum techniques in an adaptive manner. The multi-scale approach is achieved using wavelet decompositions which allow phase space density estimation to occur with scale dependent increased accuracy and variable time stepping. Possible improvements on the SFK method of Larson are discussed, including the use of multiresolution analysis based Richardson-Lucy Iteration, adaptive step size control in explicit vs implicit approaches. Examples will be shown with KEEN waves and KEEPN (Kinetic Electrostatic Electron Positron Nonlinear) waves, which are the pair plasma generalization of the former, and have a much richer span of dynamical behavior. WAKES techniques are well suited for the study of driven and released nonlinear, non-stationary, self-organized structures in phase space which have no fluid, limit nor a linear limit, and yet remain undamped and coherent well past the drive period. The work reported here is based on the Vlasov-Poisson model of plasma dynamics. Work supported by a Grant from the AFOSR.

  15. Information on stepping motors

    NASA Astrophysics Data System (ADS)

    Fongarland, G.

    1982-04-01

    The principles of the stepping motors which are often used in servomechanisms are reviewed. Variable reluctance as well as permanent magnet stepping motors are considered. Their operation is explained which includes permanent rotation, starting, stopping, and resonance effects. Several application examples, drawn from problems in automation, are outlined.

  16. STEP Experiment Requirements

    NASA Technical Reports Server (NTRS)

    Brumfield, M. L. (Compiler)

    1984-01-01

    A plan to develop a space technology experiments platform (STEP) was examined. NASA Langley Research Center held a STEP Experiment Requirements Workshop on June 29 and 30 and July 1, 1983, at which experiment proposers were invited to present more detailed information on their experiment concept and requirements. A feasibility and preliminary definition study was conducted and the preliminary definition of STEP capabilities and experiment concepts and expected requirements for support services are presented. The preliminary definition of STEP capabilities based on detailed review of potential experiment requirements is investigated. Topics discussed include: Shuttle on-orbit dynamics; effects of the space environment on damping materials; erectable beam experiment; technology for development of very large solar array deployers; thermal energy management process experiment; photovoltaic concentrater pointing dynamics and plasma interactions; vibration isolation technology; flight tests of a synthetic aperture radar antenna with use of STEP.

  17. Adaptive superposition of finite element meshes in linear and nonlinear dynamic analysis

    NASA Astrophysics Data System (ADS)

    Yue, Zhihua

    2005-11-01

    The numerical analysis of transient phenomena in solids, for instance, wave propagation and structural dynamics, is a very important and active area of study in engineering. Despite the current evolutionary state of modern computer hardware, practical analysis of large scale, nonlinear transient problems requires the use of adaptive methods where computational resources are locally allocated according to the interpolation requirements of the solution form. Adaptive analysis of transient problems involves obtaining solutions at many different time steps, each of which requires a sequence of adaptive meshes. Therefore, the execution speed of the adaptive algorithm is of paramount importance. In addition, transient problems require that the solution must be passed from one adaptive mesh to the next adaptive mesh with a bare minimum of solution-transfer error since this form of error compromises the initial conditions used for the next time step. A new adaptive finite element procedure (s-adaptive) is developed in this study for modeling transient phenomena in both linear elastic solids and nonlinear elastic solids caused by progressive damage. The adaptive procedure automatically updates the time step size and the spatial mesh discretization in transient analysis, achieving the accuracy and the efficiency requirements simultaneously. The novel feature of the s-adaptive procedure is the original use of finite element mesh superposition to produce spatial refinement in transient problems. The use of mesh superposition enables the s-adaptive procedure to completely avoid the need for cumbersome multipoint constraint algorithms and mesh generators, which makes the s-adaptive procedure extremely fast. Moreover, the use of mesh superposition enables the s-adaptive procedure to minimize the solution-transfer error. In a series of different solid mechanics problem types including 2-D and 3-D linear elastic quasi-static problems, 2-D material nonlinear quasi-static problems

  18. Adaptive processes drive ecomorphological convergent evolution in antwrens (Thamnophilidae).

    PubMed

    Bravo, Gustavo A; Remsen, J V; Brumfield, Robb T

    2014-10-01

    Phylogenetic niche conservatism (PNC) and convergence are contrasting evolutionary patterns that describe phenotypic similarity across independent lineages. Assessing whether and how adaptive processes give origin to these patterns represent a fundamental step toward understanding phenotypic evolution. Phylogenetic model-based approaches offer the opportunity not only to distinguish between PNC and convergence, but also to determine the extent that adaptive processes explain phenotypic similarity. The Myrmotherula complex in the Neotropical family Thamnophilidae is a polyphyletic group of sexually dimorphic small insectivorous forest birds that are relatively homogeneous in size and shape. Here, we integrate a comprehensive species-level molecular phylogeny of the Myrmotherula complex with morphometric and ecological data within a comparative framework to test whether phenotypic similarity is described by a pattern of PNC or convergence, and to identify evolutionary mechanisms underlying body size and shape evolution. We show that antwrens in the Myrmotherula complex represent distantly related clades that exhibit adaptive convergent evolution in body size and divergent evolution in body shape. Phenotypic similarity in the group is primarily driven by their tendency to converge toward smaller body sizes. Differences in body size and shape across lineages are associated to ecological and behavioral factors.

  19. Online adaptation and verification of VMAT

    SciTech Connect

    Crijns, Wouter; Defraene, Gilles; Depuydt, Tom; Haustermans, Karin; Van Herck, Hans; Maes, Frederik; Van den Heuvel, Frank

    2015-07-15

    Purpose: This work presents a method for fast volumetric modulated arc therapy (VMAT) adaptation in response to interfraction anatomical variations. Additionally, plan parameters extracted from the adapted plans are used to verify the quality of these plans. The methods were tested as a prostate class solution and compared to replanning and to their current clinical practice. Methods: The proposed VMAT adaptation is an extension of their previous intensity modulated radiotherapy (IMRT) adaptation. It follows a direct (forward) planning approach: the multileaf collimator (MLC) apertures are corrected in the beam’s eye view (BEV) and the monitor units (MUs) are corrected using point dose calculations. All MLC and MU corrections are driven by the positions of four fiducial points only, without need for a full contour set. Quality assurance (QA) of the adapted plans is performed using plan parameters that can be calculated online and that have a relation to the delivered dose or the plan quality. Five potential parameters are studied for this purpose: the number of MU, the equivalent field size (EqFS), the modulation complexity score (MCS), and the components of the MCS: the aperture area variability (AAV) and the leaf sequence variability (LSV). The full adaptation and its separate steps were evaluated in simulation experiments involving a prostate phantom subjected to various interfraction transformations. The efficacy of the current VMAT adaptation was scored by target mean dose (CTV{sub mean}), conformity (CI{sub 95%}), tumor control probability (TCP), and normal tissue complication probability (NTCP). The impact of the adaptation on the plan parameters (QA) was assessed by comparison with prediction intervals (PI) derived from a statistical model of the typical variation of these parameters in a population of VMAT prostate plans (n = 63). These prediction intervals are the adaptation equivalent of the tolerance tables for couch shifts in the current clinical

  20. The Next Giant Step

    NASA Video Gallery

    Artist Robert McCall painted "The Next Giant Step" in 1979 to commemorate the heroism and courage of spaceflight pioneers. Located in the lobby of Johnson's building 2, the mural depicts America's ...

  1. CEIP Next Steps

    EPA Pesticide Factsheets

    The Clean Energy Incentive Program (CEIP) next steps document details the EPA’s outreach strategy for stakeholder input on the design and implementation of the CEIP. Additionally, this document lists provisions on the CEIP where stakeholder input is sought

  2. Transformational adaptation when incremental adaptations to climate change are insufficient.

    PubMed

    Kates, Robert W; Travis, William R; Wilbanks, Thomas J

    2012-05-08

    All human-environment systems adapt to climate and its natural variation. Adaptation to human-induced change in climate has largely been envisioned as increments of these adaptations intended to avoid disruptions of systems at their current locations. In some places, for some systems, however, vulnerabilities and risks may be so sizeable that they require transformational rather than incremental adaptations. Three classes of transformational adaptations are those that are adopted at a much larger scale, that are truly new to a particular region or resource system, and that transform places and shift locations. We illustrate these with examples drawn from Africa, Europe, and North America. Two conditions set the stage for transformational adaptation to climate change: large vulnerability in certain regions, populations, or resource systems; and severe climate change that overwhelms even robust human use systems. However, anticipatory transformational adaptation may be difficult to implement because of uncertainties about climate change risks and adaptation benefits, the high costs of transformational actions, and institutional and behavioral actions that tend to maintain existing resource systems and policies. Implementing transformational adaptation requires effort to initiate it and then to sustain the effort over time. In initiating transformational adaptation focusing events and multiple stresses are important, combined with local leadership. In sustaining transformational adaptation, it seems likely that supportive social contexts and the availability of acceptable options and resources for actions are key enabling factors. Early steps would include incorporating transformation adaptation into risk management and initiating research to expand the menu of innovative transformational adaptations.

  3. Transformational adaptation when incremental adaptations to climate change are insufficient

    PubMed Central

    Kates, Robert W.; Travis, William R.; Wilbanks, Thomas J.

    2012-01-01

    All human–environment systems adapt to climate and its natural variation. Adaptation to human-induced change in climate has largely been envisioned as increments of these adaptations intended to avoid disruptions of systems at their current locations. In some places, for some systems, however, vulnerabilities and risks may be so sizeable that they require transformational rather than incremental adaptations. Three classes of transformational adaptations are those that are adopted at a much larger scale, that are truly new to a particular region or resource system, and that transform places and shift locations. We illustrate these with examples drawn from Africa, Europe, and North America. Two conditions set the stage for transformational adaptation to climate change: large vulnerability in certain regions, populations, or resource systems; and severe climate change that overwhelms even robust human use systems. However, anticipatory transformational adaptation may be difficult to implement because of uncertainties about climate change risks and adaptation benefits, the high costs of transformational actions, and institutional and behavioral actions that tend to maintain existing resource systems and policies. Implementing transformational adaptation requires effort to initiate it and then to sustain the effort over time. In initiating transformational adaptation focusing events and multiple stresses are important, combined with local leadership. In sustaining transformational adaptation, it seems likely that supportive social contexts and the availability of acceptable options and resources for actions are key enabling factors. Early steps would include incorporating transformation adaptation into risk management and initiating research to expand the menu of innovative transformational adaptations. PMID:22509036

  4. Class Size.

    ERIC Educational Resources Information Center

    Underwood, Siobhan; Lumsden, Linda S.

    1994-01-01

    The items featured in this annotated bibliography touch on several aspects of the multifaceted class-size debate. Allen Odden reviews the literature and contends that class-size reduction should be used "sparingly and strategically." C. M. Achilles and colleagues examines two different class-size situations and find student test…

  5. Stepped frequency ground penetrating radar

    DOEpatents

    Vadnais, Kenneth G.; Bashforth, Michael B.; Lewallen, Tricia S.; Nammath, Sharyn R.

    1994-01-01

    A stepped frequency ground penetrating radar system is described comprising an RF signal generating section capable of producing stepped frequency signals in spaced and equal increments of time and frequency over a preselected bandwidth which serves as a common RF signal source for both a transmit portion and a receive portion of the system. In the transmit portion of the system the signal is processed into in-phase and quadrature signals which are then amplified and then transmitted toward a target. The reflected signals from the target are then received by a receive antenna and mixed with a reference signal from the common RF signal source in a mixer whose output is then fed through a low pass filter. The DC output, after amplification and demodulation, is digitized and converted into a frequency domain signal by a Fast Fourier Transform. A plot of the frequency domain signals from all of the stepped frequencies broadcast toward and received from the target yields information concerning the range (distance) and cross section (size) of the target.

  6. A gradient-adaptive lattice-based complex adaptive notch filter

    NASA Astrophysics Data System (ADS)

    Zhu, Rui; Yang, Feiran; Yang, Jun

    2016-12-01

    This paper presents a new complex adaptive notch filter to estimate and track the frequency of a complex sinusoidal signal. The gradient-adaptive lattice structure instead of the traditional gradient one is adopted to accelerate the convergence rate. It is proved that the proposed algorithm results in unbiased estimations by using the ordinary differential equation approach. The closed-form expressions for the steady-state mean square error and the upper bound of step size are also derived. Simulations are conducted to validate the theoretical analysis and demonstrate that the proposed method generates considerably better convergence rates and tracking properties than existing methods, particularly in low signal-to-noise ratio environments.

  7. Subcellular Size

    PubMed Central

    Marshall, Wallace F.

    2016-01-01

    All of the same conceptual questions about size in organisms apply equally at the level of single cells. What determines the size, not only of the whole cell, but of all its parts? What ensures that subcellular components are properly proportioned relative to the whole cell? How does alteration in organelle size affect biochemical function? Answering such fundamental questions requires us to understand how the size of individual organelles and other cellular structures is determined. Knowledge of organelle biogenesis and dynamics has advanced rapidly in recent years. Does this knowledge give us enough information to formulate reasonable models for organelle size control, or are we still missing something? PMID:25957302

  8. Visual Adaptation

    PubMed Central

    Webster, Michael A.

    2015-01-01

    Sensory systems continuously mold themselves to the widely varying contexts in which they must operate. Studies of these adaptations have played a long and central role in vision science. In part this is because the specific adaptations remain a powerful tool for dissecting vision, by exposing the mechanisms that are adapting. That is, “if it adapts, it's there.” Many insights about vision have come from using adaptation in this way, as a method. A second important trend has been the realization that the processes of adaptation are themselves essential to how vision works, and thus are likely to operate at all levels. That is, “if it's there, it adapts.” This has focused interest on the mechanisms of adaptation as the target rather than the probe. Together both approaches have led to an emerging insight of adaptation as a fundamental and ubiquitous coding strategy impacting all aspects of how we see. PMID:26858985

  9. A fragment based step-by-step strategy for determining the most stable conformers of biomolecules

    NASA Astrophysics Data System (ADS)

    Li, Hongbao; Lin, Zijing; Luo, Yi

    2014-08-01

    For biomolecules of increased size and flexibility, more efficient and reliable strategies are always needed to determine their stable low-energy conformers. Here, we propose a fragment based step-by-step strategy to search for the full conformational space of biomolecules. In this strategy, the molecule is divided into several fragments and each of them is systematically optimized in a step-by-step fashion. It can significantly reduce the computational cost without losing any accuracy as demonstrated by the conformer search of several representative di-/tri-/tetra-peptides. Such an approach will be very useful for finding the stable conformers of large biomolecules.

  10. Global error estimation based on the tolerance proportionality for some adaptive Runge-Kutta codes

    NASA Astrophysics Data System (ADS)

    Calvo, M.; González-Pinto, S.; Montijano, J. I.

    2008-09-01

    Modern codes for the numerical solution of Initial Value Problems (IVPs) in ODEs are based in adaptive methods that, for a user supplied tolerance [delta], attempt to advance the integration selecting the size of each step so that some measure of the local error is [similar, equals][delta]. Although this policy does not ensure that the global errors are under the prescribed tolerance, after the early studies of Stetter [Considerations concerning a theory for ODE-solvers, in: R. Burlisch, R.D. Grigorieff, J. Schröder (Eds.), Numerical Treatment of Differential Equations, Proceedings of Oberwolfach, 1976, Lecture Notes in Mathematics, vol. 631, Springer, Berlin, 1978, pp. 188-200; Tolerance proportionality in ODE codes, in: R. März (Ed.), Proceedings of the Second Conference on Numerical Treatment of Ordinary Differential Equations, Humbold University, Berlin, 1980, pp. 109-123] and the extensions of Higham [Global error versus tolerance for explicit Runge-Kutta methods, IMA J. Numer. Anal. 11 (1991) 457-480; The tolerance proportionality of adaptive ODE solvers, J. Comput. Appl. Math. 45 (1993) 227-236; The reliability of standard local error control algorithms for initial value ordinary differential equations, in: Proceedings: The Quality of Numerical Software: Assessment and Enhancement, IFIP Series, Springer, Berlin, 1997], it has been proved that in many existing explicit Runge-Kutta codes the global errors behave asymptotically as some rational power of [delta]. This step-size policy, for a given IVP, determines at each grid point tn a new step-size hn+1=h(tn;[delta]) so that h(t;[delta]) is a continuous function of t. In this paper a study of the tolerance proportionality property under a discontinuous step-size policy that does not allow to change the size of the step if the step-size ratio between two consecutive steps is close to unity is carried out. This theory is applied to obtain global error estimations in a few problems that have been solved with

  11. Adaptive Management

    EPA Science Inventory

    Adaptive management is an approach to natural resource management that emphasizes learning through management where knowledge is incomplete, and when, despite inherent uncertainty, managers and policymakers must act. Unlike a traditional trial and error approach, adaptive managem...

  12. A GPU-accelerated adaptive discontinuous Galerkin method for level set equation

    NASA Astrophysics Data System (ADS)

    Karakus, A.; Warburton, T.; Aksel, M. H.; Sert, C.

    2016-01-01

    This paper presents a GPU-accelerated nodal discontinuous Galerkin method for the solution of two- and three-dimensional level set (LS) equation on unstructured adaptive meshes. Using adaptive mesh refinement, computations are localised mostly near the interface location to reduce the computational cost. Small global time step size resulting from the local adaptivity is avoided by local time-stepping based on a multi-rate Adams-Bashforth scheme. Platform independence of the solver is achieved with an extensible multi-threading programming API that allows runtime selection of different computing devices (GPU and CPU) and different threading interfaces (CUDA, OpenCL and OpenMP). Overall, a highly scalable, accurate and mass conservative numerical scheme that preserves the simplicity of LS formulation is obtained. Efficiency, performance and local high-order accuracy of the method are demonstrated through distinct numerical test cases.

  13. Stepped inlet optical panel

    DOEpatents

    Veligdan, James T.

    2001-01-01

    An optical panel includes stacked optical waveguides having stepped inlet facets collectively defining an inlet face for receiving image light, and having beveled outlet faces collectively defining a display screen for displaying the image light channeled through the waveguides by internal reflection.

  14. Quick and Easy Adaptations and Accommodations for Early Childhood Students

    ERIC Educational Resources Information Center

    Breitfelder, Leisa M.

    2008-01-01

    Research-based information is used to support the idea of the use of adaptations and accommodations for early childhood students who have varying disabilities. Multiple adaptations and accommodations are outlined. A step-by-step plan is provided on how to make specific adaptations and accommodations to fit the specific needs of early childhood…

  15. Adaptive strategies for materials design using uncertainties

    SciTech Connect

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-21

    Here, we compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.

  16. Adaptive strategies for materials design using uncertainties

    DOE PAGES

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; ...

    2016-01-21

    Here, we compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material withmore » desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.« less

  17. Adaptive Strategies for Materials Design using Uncertainties

    PubMed Central

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-01

    We compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties. PMID:26792532

  18. Optimal time step for incompressible SPH

    NASA Astrophysics Data System (ADS)

    Violeau, Damien; Leroy, Agnès

    2015-05-01

    A classical incompressible algorithm for Smoothed Particle Hydrodynamics (ISPH) is analyzed in terms of critical time step for numerical stability. For this purpose, a theoretical linear stability analysis is conducted for unbounded homogeneous flows, leading to an analytical formula for the maximum CFL (Courant-Friedrichs-Lewy) number as a function of the Fourier number. This gives the maximum time step as a function of the fluid viscosity, the flow velocity scale and the SPH discretization size (kernel standard deviation). Importantly, the maximum CFL number at large Reynolds number appears twice smaller than with the traditional Weakly Compressible (WCSPH) approach. As a consequence, the optimal time step for ISPH is only five times larger than with WCSPH. The theory agrees very well with numerical data for two usual kernels in a 2-D periodic flow. On the other hand, numerical experiments in a plane Poiseuille flow show that the theory overestimates the maximum allowed time step for small Reynolds numbers.

  19. Microstructure of room temperature ionic liquids at stepped graphite electrodes

    SciTech Connect

    Feng, Guang; Li, Song; Zhao, Wei; Cummings, Peter T.

    2015-07-14

    Molecular dynamics simulations of room temperature ionic liquid (RTIL) [emim][TFSI] at stepped graphite electrodes were performed to investigate the influence of the thickness of the electrode surface step on the microstructure of interfacial RTILs. A strong correlation was observed between the interfacial RTIL structure and the step thickness in electrode surface as well as the ion size. Specifically, when the step thickness is commensurate with ion size, the interfacial layering of cation/anion is more evident; whereas, the layering tends to be less defined when the step thickness is close to the half of ion size. Furthermore, two-dimensional microstructure of ion layers exhibits different patterns and alignments of counter-ion/co-ion lattice at neutral and charged electrodes. As the cation/anion layering could impose considerable effects on ion diffusion, the detailed information of interfacial RTILs at stepped graphite presented here would help to understand the molecular mechanism of RTIL-electrode interfaces in supercapacitors.

  20. Osteogenic index of step exercise depending on choreographic movements, session duration, and stepping rate

    PubMed Central

    Santos‐Rocha, R A; Oliveira, C S; Veloso, A P

    2006-01-01

    Background Step exercise has been promoted as a low impact physical activity recommended for the improvement of cardiorespiratory and muscular fitness. This recreational activity might also be recommended to improve bone health since mechanical load plays an important role in the normal development of the skeleton. Methods Our main purpose was to characterised 100 step sessions and to calculated osteogenic index (OI) according to Turner and Robling: OI (one session) = peak ground reaction force(BW)*ln(number of loading cycles+1). Results Main results (mean±SD) were as follows: OI was 12.0±0.8; peak ground reaction force (GRF) was 1.40±0.10 times body weight (BW); session duration was 38.6±8.3 min; stepping rate was 134.6±4.7 beats per minute (bpm); the movements performed most often were marching, knee hop, side leg, L step, and over the top; and the number of loading cycles was 4194.1±1055.2. OI and GRF increased significantly when stepping rate was higher than 135 bpm. This stepping rate might be used as a reference for higher intensity classes. A frequency of two to three sessions per week of step exercise is recommended. Conclusions Despite the benefits that have been stated when step classes are structured correctly and adapted to the participants, further research is needed concerning biomechanical load, exercise prescription, and injury prevention. PMID:16920771

  1. Step Prototype Development Status

    NASA Astrophysics Data System (ADS)

    Mehls, C.; Bayart, C.; Bower, J.; Clarke, B.; Cox, C.; Gill, D.; Stricker, D.; Vora, N.; Wang, S.; Zhou, P.; Torii, R.; Worden, P.; Debra, D.; Dittus, H.; Loeffler, F.

    2008-09-01

    STEP, the Satellite Test of the Equivalence Principle [1], proposes to test the Equivalence Principle to a part in 1018 by comparing the free-fall acceleration of cylindrical shaped test masses [2] in Earth orbit. Magnetic bearings constrain the test mass motion to their axis of symmetry [3]. The displacement of the test masses is measured using a DC SQUID and superconducting coils [4], enabling a displacement sensitivity as small as 10-15 m. In combination with a small spring stiffness a differential acceleration sensitivity of 10-18 g is achievable. Residual satellite acceleration is reduced to better than 10-14 g by compensating satellite drag forces with thrust provided by helium gas. We report on recent progress in the development of STEP prototype flight accelerometers, in particular the development of the high precision quartz housing for the engineering inner accelerometer and the testing of SQUID and capacitive readout systems using 'brass board' accelerometer prototypes.

  2. The digital step edge

    NASA Technical Reports Server (NTRS)

    Haralick, R. M.

    1982-01-01

    The facet model was used to accomplish step edge detection. The essence of the facet model is that any analysis made on the basis of the pixel values in some neighborhood has its final authoritative interpretation relative to the underlying grey tone intensity surface of which the neighborhood pixel values are observed noisy samples. Pixels which are part of regions have simple grey tone intensity surfaces over their areas. Pixels which have an edge in them have complex grey tone intensity surfaces over their areas. Specially, an edge moves through a pixel only if there is some point in the pixel's area having a zero crossing of the second directional derivative taken in the direction of a non-zero gradient at the pixel's center. To determine whether or not a pixel should be marked as a step edge pixel, its underlying grey tone intensity surface was estimated on the basis of the pixels in its neighborhood.

  3. Steps toward hypertelescopes on Earth and in space

    NASA Astrophysics Data System (ADS)

    Labeyrie, A.; Le Coroller, H.; Dejonghe, J.

    2008-07-01

    For imaging faint and complex sources at high angular resolution, hypertelescopes (direct-imaging many-aperture interferometers using a densified pupil) gain sensitivity with respect to few-aperture interferometers and to Fizeau interferometers. Steps are taken to expand the Carlina-Proto technical prototype built at Observatoire de Haute-Provence, 18m in aperture size, and to define a larger (100-200m) Carlina-Science version, incorporating 100 or more small apertures. Following initial observing by Speckle Interferometry, adaptive co-pistoning is expected to become available, using "Dispersed Speckle" piston sensing on bright stars, and a modified Laser Guide Star on faint (mv > 25) fields. "Extremely Large Hypertelescope" versions of such instruments, with aperture size beyond a kilometer, are considered for deep-field imaging on cosmological sources. These can be interferometrically coupled with ELTs, or arrays of telescopes, at sites such as the Macon range (Andes) considered by ESO for its E-ELT. Space versions are proposed to ESA and NASA.

  4. Dynamic pupillary response controlled by the pupil size effect.

    PubMed

    Sun, F; Tauchi, P; Stark, L

    1983-11-01

    Pupillary escape has been described as an initial contraction followed by a slow redilatation, occurring in response to a step stimulus of low-intensity light. When the initial pupil size is small, the response to the same step stimulus is pupillary capture, a steady and sustained contraction. In this experiment a comparison was made between three modes of controlling pupil size and thereby of regulating the pupillary response: contralateral light background level, ipsilateral light background level, and accommodative level with which there is no change in retinal adaptation. All three level setting modes showed similar results in illustrating the pupil size effect. In addition, an inhibitory effect was found with both ipsilateral and contralateral light backgrounds that is independent of Weber's Law in the contralateral case. Our results lead to the formulation of a binocular model, featuring an internal parameter control whereby a signal dependent on the static pupil size regulates the gains of the parallel phasic and tonic pathways, the former responsive to transient changes of light, and the latter to background levels of light and accommodative levels. Our findings also raise interesting questions concerning the loci of these complex interactions in the simple neuroanatomy of the pupillary pathways.

  5. 3D Structured Grid Adaptation

    NASA Technical Reports Server (NTRS)

    Banks, D. W.; Hafez, M. M.

    1996-01-01

    Grid adaptation for structured meshes is the art of using information from an existing, but poorly resolved, solution to automatically redistribute the grid points in such a way as to improve the resolution in regions of high error, and thus the quality of the solution. This involves: (1) generate a grid vis some standard algorithm, (2) calculate a solution on this grid, (3) adapt the grid to this solution, (4) recalculate the solution on this adapted grid, and (5) repeat steps 3 and 4 to satisfaction. Steps 3 and 4 can be repeated until some 'optimal' grid is converged to but typically this is not worth the effort and just two or three repeat calculations are necessary. They also may be repeated every 5-10 time steps for unsteady calculations.

  6. Step Detection Robust against the Dynamics of Smartphones

    PubMed Central

    Lee, Hwan-hee; Choi, Suji; Lee, Myeong-jin

    2015-01-01

    A novel algorithm is proposed for robust step detection irrespective of step mode and device pose in smartphone usage environments. The dynamics of smartphones are decoupled into a peak-valley relationship with adaptive magnitude and temporal thresholds. For extracted peaks and valleys in the magnitude of acceleration, a step is defined as consisting of a peak and its adjacent valley. Adaptive magnitude thresholds consisting of step average and step deviation are applied to suppress pseudo peaks or valleys that mostly occur during the transition among step modes or device poses. Adaptive temporal thresholds are applied to time intervals between peaks or valleys to consider the time-varying pace of human walking or running for the correct selection of peaks or valleys. From the experimental results, it can be seen that the proposed step detection algorithm shows more than 98.6% average accuracy for any combination of step mode and device pose and outperforms state-of-the-art algorithms. PMID:26516857

  7. Platelet size in man.

    PubMed

    Paulus, J M

    1975-09-01

    The shape and parameters of platelet size distributions were studied in 50 normal persons and 97 patients in order to test the proposed thesis that platelet size heterogeneity results mainly from aging in the circulation. This thesis was contradicted (1) by size distributions of age-homogeneous, newly-born cell populations which were lognormal with increased (instead of decreased) dispersion of volumes and (2) by the macrothrombocytosis found in some populations with normal age distribution. For these reasons, thrombocytopoiesis appeared to play the major role in determining platelet size. A model was built in which the volume variation of platelet territories due to megakaryocyte growth and membrane demarcation at each step of maturation was a random proportion of the previous value of the volume. This model explains the lognormal shape of both newborn and circulating platelet size distributions. It also implies that (1) the mean and standard deviation of platelet logvolumes depend on the rates of volume change of the individual platelet territories (growth rate minus demarcation rate) as well as on megakaryocyte maturation time; (2) platelet hyperdestruction causes an increase in the mean and dispersion of the rates of territory volume change; (3) Mediterranean macrothrombocytosis and some hereditary macrothrombocytotic thrombocytopenias or dysthrombocytopoieses reflect a diminished rate of territory demarcation, and (4) platelet size heterogeneity is caused mainly by the variations in territory growth and demarcation and not by aging in the circulation.

  8. Step proof mass dynamics

    NASA Astrophysics Data System (ADS)

    Wiegand, M.; Scheithauer, S.; Theil, S.

    2004-05-01

    The Satellite Test of Equivalence Principle (STEP) is a joint European-US project to investigate one of the most fundamental principles in physics, the Equivalence of inertia and passive gravitational mass. As STEP matures into a flight program, the development of a precise spacecraft dynamics simulator becomes crucial. The simulator is primarily needed for design, test and verification of the drag-free control (DFC) system and the flight software. The drag-free concept involves centering the proof mass located inside a satellite. As the proof mass is free of external disturbances (drag free), it follows a purely gravitational orbit. Since the satellite is forced to follow the proof mass, it too follows the same gravitational orbit, canceling all non-gravitational forces. For the STEP Mission, the DFC system is required to attenuate any disturbance forces acting on the spacecraft to achieve residual acceleration at location of the accelerometer of less than 3×10 -14 m/s2 (rms) across the measurement bandwidth. While the simulator is based on a high-fidelity six-degree-of-freedom numerical simulation, a simplified model is used to analyze the proof mass dynamics. The stability analysis of the proof mass motion is performed by transformation of the simplified model into the standard form of the Mathieu differential equation. The stability regions of the solution are applied to choose proper values for parameters like coupling forces between satellite and proof mass as a function of spacecraft rotation. The paper describes the calculation of the spacecraft/payload dynamics and the assumptions used to derive the underlying algorithms with a special emphasis on numerical precision issues.

  9. New photolithography stepping machine

    SciTech Connect

    Hale, L.; Klingmann, J.; Markle, D.

    1995-03-08

    A joint development project to design a new photolithography steeping machine capable of 150 nanometer overlay accuracy was completed by Ultratech Stepper and the Lawrence Livermore National Laboratory. The principal result of the project is a next-generation product that will strengthen the US position in step-and-repeat photolithography. The significant challenges addressed and solved in the project are the subject of this report. Design methods and new devices that have broader application to precision machine design are presented in greater detail while project specific information serves primarily as background and motivation.

  10. Steps to the moon

    USGS Publications Warehouse

    ,; Dale, Alvin E.

    1976-01-01

    On July 20, 1969, man walked on the surface of the Moon and began a new chapter of his studies that will eventually disclose the geologic nature of the Earth's nearest neighbor. Although he has finally reached the Moon and sampled its substance, much work and study remain before he will know the full scientific significance of the first landing. This booklet briefly summarizes the steps man has taken to understand the Moon and what he thinks he has learned to date as a result of his centuries-long speculations and studies.

  11. A Reconfigurable Stepping Motor

    NASA Astrophysics Data System (ADS)

    Rogers, Charles; Selvaggi, Richard

    2009-04-01

    Multiphase brushless actuators, commonly known as the stepper motors, are ubiquitous for many precision control applications. Developments in the microelectronics have lead to their use as efficient drive motors for modern electric vehicles. Understanding the physics and the control logic for interfacing these transducers continues to be important for scientists and engineers. An overview of the stepping motor principles and interfacing requirements is presented and a simple working model used to teach the concepts of stepper motors is described and demonstrated. This model was used to design a much larger stepper motor required to precisely rotate a massive optical system in the undergraduate advanced physics laboratory.

  12. Prospective Adaptation in the Use of External Representations

    ERIC Educational Resources Information Center

    Martin, Lee; Schwartz, Daniel L.

    2009-01-01

    An important element of adaptive expertise involves stepping away from a routine to retool one's knowledge or environment. The current study investigated two forms of this adaptive pattern: fault-driven adaptations, which are reactions to a difficulty, and prospective adaptations, which are proactive reformulations. Graduate and undergraduate…

  13. Climate adaptation

    NASA Astrophysics Data System (ADS)

    Kinzig, Ann P.

    2015-03-01

    This paper is intended as a brief introduction to climate adaptation in a conference devoted otherwise to the physics of sustainable energy. Whereas mitigation involves measures to reduce the probability of a potential event, such as climate change, adaptation refers to actions that lessen the impact of climate change. Mitigation and adaptation differ in other ways as well. Adaptation does not necessarily have to be implemented immediately to be effective; it only needs to be in place before the threat arrives. Also, adaptation does not necessarily require global, coordinated action; many effective adaptation actions can be local. Some urban communities, because of land-use change and the urban heat-island effect, currently face changes similar to some expected under climate change, such as changes in water availability, heat-related morbidity, or changes in disease patterns. Concern over those impacts might motivate the implementation of measures that would also help in climate adaptation, despite skepticism among some policy makers about anthropogenic global warming. Studies of ancient civilizations in the southwestern US lends some insight into factors that may or may not be important to successful adaptation.

  14. SPAR-H Step-by-Step Guidance

    SciTech Connect

    W. J. Galyean; A. M. Whaley; D. L. Kelly; R. L. Boring

    2011-05-01

    This guide provides step-by-step guidance on the use of the SPAR-H method for quantifying Human Failure Events (HFEs). This guide is intended to be used with the worksheets provided in: 'The SPAR-H Human Reliability Analysis Method,' NUREG/CR-6883, dated August 2005. Each step in the process of producing a Human Error Probability (HEP) is discussed. These steps are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff. The discussions on dependence are extensive and include an appendix that describes insights obtained from the psychology literature.

  15. Free energy of steps using atomistic simulations

    NASA Astrophysics Data System (ADS)

    Freitas, Rodrigo; Frolov, Timofey; Asta, Mark

    The properties of solid-liquid interfaces are known to play critical roles in solidification processes. Particularly special importance is given to thermodynamic quantities that describe the equilibrium state of these surfaces. For example, on the solid-liquid-vapor heteroepitaxial growth of semiconductor nanowires the crystal nucleation process on the faceted solid-liquid interface is influenced by the solid-liquid and vapor-solid interfacial free energies, and also by the free energies of associated steps at these faceted interfaces. Crystal-growth theories and mesoscale simulation methods depend on quantitative information about these properties, which are often poorly characterized from experimental measurements. In this work we propose an extension of the capillary fluctuation method for calculation of the free energy of steps on faceted crystal surfaces. From equilibrium atomistic simulations of steps on (111) surfaces of Copper we computed accurately the step free energy for different step orientations. We show that the step free energy remains finite at all temperature up to the melting point and that the results obtained agree with the more well established method of thermodynamic integration if finite size effects are taken into account. The research of RF and MA at UC Berkeley were supported by the US National Science Foundation (Grant No. DMR-1105409). TF acknowledges support through a postdoctoral fellowship from the Miller Institute for Basic Research in Science.

  16. A spatially and temporally adaptive solution of Richards’ equation

    NASA Astrophysics Data System (ADS)

    Miller, Cass T.; Abhishek, Chandra; Farthing, Matthew W.

    2006-04-01

    Efficient, robust simulation of groundwater flow in the unsaturated zone remains computationally expensive, especially for problems characterized by sharp fronts in both space and time. Standard approaches that employ uniform spatial and temporal discretizations for the numerical solution of these problems lead to inefficient and expensive simulations. In this work, we solve Richards' equation using adaptive methods in both space and time. Spatial adaption is based upon a coarse grid solve and a gradient error indicator using a fixed-order approximation. Temporal adaption is accomplished using variable order, variable step size approximations based upon the backward difference formulas up to fifth order. Since the advantages of similar adaptive methods in time are now established, we evaluate our method by comparison with a uniform spatial discretization that is adaptive in time for four different one-dimensional test problems. The numerical results demonstrate that the proposed method provides a robust and efficient alternative to standard approaches for simulating variably saturated flow in one spatial dimension.

  17. Exploring Size.

    ERIC Educational Resources Information Center

    Brand, Judith, Ed.

    1995-01-01

    "Exploring" is a magazine of science, art, and human perception that communicates ideas museum exhibits cannot demonstrate easily by using experiments and activities for the classroom. This issue concentrates on size, examining it from a variety of viewpoints. The focus allows students to investigate and discuss interconnections among…

  18. Adaptation through proportion

    NASA Astrophysics Data System (ADS)

    Xiong, Liyang; Shi, Wenjia; Tang, Chao

    2016-08-01

    Adaptation is a ubiquitous feature in biological sensory and signaling networks. It has been suggested that adaptive systems may follow certain simple design principles across diverse organisms, cells and pathways. One class of networks that can achieve adaptation utilizes an incoherent feedforward control, in which two parallel signaling branches exert opposite but proportional effects on the output at steady state. In this paper, we generalize this adaptation mechanism by establishing a steady-state proportionality relationship among a subset of nodes in a network. Adaptation can be achieved by using any two nodes in the sub-network to respectively regulate the output node positively and negatively. We focus on enzyme networks and first identify basic regulation motifs consisting of two and three nodes that can be used to build small networks with proportional relationships. Larger proportional networks can then be constructed modularly similar to LEGOs. Our method provides a general framework to construct and analyze a class of proportional and/or adaptation networks with arbitrary size, flexibility and versatile functional features.

  19. [Effects of stepped counseling intervention on quality of life among newly diagnosed HIV-positive patients].

    PubMed

    Hsiao, Ching-Fang; Chao, Shu-Ling; Tsai, Tsui-Ching; Chuang, Peing

    2004-04-01

    The purpose of this research was to understand how stepped counseling intervention affects quality of life in newly diagnosed HIV-positive patients. The study made use of quasi-experimental methodology that included a three-step interview process over 45 days. The theoretical framework supporting interviews with 32 newly diagnosed HIV-positive patients in northern Taiwan included a combination of rational-emotive therapy, cognitive-behavior therapy, and health education. Participants were divided into an experimental and control group of equal size. Data collection also included responses to the WHOQOL-HIV instrument at the beginning and end of each interview session. Responses were analyzed with the SPSS software package. The results showed a 25-point difference between pre- and post-test scores in the experimental group (SD = 3.2) and a 6 point difference in the control group (SD = 4.3). The results indicate that stepped counseling techniques are effective in helping this patient population to adjust to the physical, emotional, social, and environmental stresses associated with their newly diagnosis. The researchers suggest that stepped counseling be used with all newly diagnosed HIV-positive Taiwanese patients in all hospitals and clinics to promote adaptive abilities and to control the further spread of HIV.

  20. Stair-stepped Mound

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-429, 22 July 2003

    This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a stair-stepped mound of sedimentary rock (right of center) on the floor of a large impact crater in western Arabia Terra near 11.0oN, 4.4oW. Sedimentary rock outcrops are common in the craters of this region. The repeated thickness and uniformity of the layers that make up this mound suggest that their depositional environment was one in which cyclic or episodic events occurred over some period of time. The sediments might have been deposited in a lake, or they may have settled directly out of the atmosphere. Most of the layered material was later eroded away, leaving this circular mound and the other nearby mesas and knobs. The image is illuminated by sunlight from the lower left.

  1. Portable Slot-Sizing Tool

    NASA Technical Reports Server (NTRS)

    Zuver, Nelson T.

    1987-01-01

    Portable milling tool consisting of air-motor-driven cutter held in adjustable moving slide made possible local removal of chromium plating in close-tolerance, onsite remachining and sizing of half-hole slots on longeron bridges. Made from commercially available parts, including air motor capable of variable speeds up to 900 rpm, ball end mill, revolving handle, two miter gears, and ball slide. Adaptation of portable sizing tool useful for field modification of such large equipment as trucks, aircraft, and ships.

  2. Adaptation of naturally paced saccades

    PubMed Central

    Blangero, Annabelle; Herman, James P.; Wallman, Josh; Harwood, Mark R.

    2014-01-01

    In the natural environment, humans make saccades almost continuously. In many eye movement experiments, however, observers are required to fixate for unnaturally long periods of time. The resulting long and monotonous experimental sessions can become especially problematic when collecting data in a clinical setting, where time can be scarce and subjects easily fatigued. With this in mind, we tested whether the well-studied motor learning process of saccade adaptation could be induced with a dramatically shortened intertrial interval. Observers made saccades to targets that stepped left or right either ∼250 ms or ∼1,600 ms after the saccade landed. In experiment I, we tested baseline saccade parameters to four different target amplitudes (5°, 10°, 15°, and 20°) in the two timing settings. In experiments II and III, we adapted 10° saccades via 2° intrasaccadic steps either backwards or forwards, respectively. Seven subjects performed eight separate adaptation sessions (2 intertrial timings × 2 adaptation direction × 2 session trial lengths). Adaptation proceeded remarkably similarly in both timing conditions across the multiple sessions. In the faster-paced sessions, robust adaptation was achieved in under 2 min, demonstrating the efficacy of our approach to streamlining saccade adaptation experiments. Although saccade amplitudes were similar between conditions, the faster-paced condition unexpectedly resulted in significantly higher peak velocities in all subjects. This surprising finding demonstrates that the stereotyped “main sequence” relationship between saccade amplitude and peak velocity is not as fixed as originally thought. PMID:24623511

  3. Use of adapted Aspergillus niger in the bioleaching of spent refinery processing catalyst.

    PubMed

    Santhiya, Deenan; Ting, Yen-Peng

    2006-01-02

    Spent refinery processing catalyst is listed as a hazardous waste; the toxicity characteristic leaching procedure (TCLP) extracts of the catalyst are found to contain heavy metals at concentrations exceeding the regulated levels. In the present investigation, Aspergillus niger was adapted to single metal ions Ni, Mo or Al (at 100-2,000 mg/L in steps of 100mg/L) and then to a mixture of Ni, Mo and Al (at a mass ratio of 1:2:6, as approximately present in the spent catalyst). Adaptation experiments with single metals showed that the fungus could tolerate up to 1,000 mg/L Ni, 1,200 mg/L Mo and 2,000 mg/L Al. In the presence of a mixture of these metals, the fungus was able to tolerate up to 100mg/L Ni, 200mg/L Mo and 600 mg/L Al. One-step bioleaching experiments with 1 wt% spent catalyst (of particle size <37 microm) were carried out using un-adapted and various adapted fungal strains. In contrast to the adapted strains, the un-adapted strain showed no growth in the presence of the catalyst. Ni:Mo:Al-adapted strain was the most efficient in the leaching of metals from the catalyst (at 78.5% Ni, 82.3% Mo and 65.2% Al) over 30 days due to its tolerance to the toxic elements at 1 wt%. More importantly, the Ni:Mo:Al-adapted strain was capable of bioleaching up to 3 wt% spent catalyst. The TCLP extracts of the spent catalyst after bioleaching using the Ni:Mo:Al-adapted strain showed the concentrations of Ni and Mo were well within the regulated levels.

  4. Green Schools Energy Project: A Step-by-Step Manual.

    ERIC Educational Resources Information Center

    Quigley, Gwen

    This publication contains a step-by-step guide for implementing an energy-saving project in local school districts: the installation of newer, more energy-efficient "T-8" fluorescent tube lights in place of "T-12" lights. Eleven steps are explained in detail: (1) find out what kind of lights the school district currently uses;…

  5. Steps per day: the road to senior health?

    PubMed

    Aoyagi, Yukitoshi; Shephard, Roy J

    2009-01-01

    In older adults, as in younger individuals, habitual moderate-intensity physical activity is associated with a reduced risk of various chronic health conditions, including certain types of cardiovascular and musculoskeletal disease and certain forms of cancer. However, the pattern of physical activity associated with such benefits remains unclear. One problem is that most investigators have examined patterns of physical activity using either subjective questionnaires or accelerometer or pedometer measurements limited to a single week, despite clear evidence of both the unreliability/invalidity of questionnaires and seasonal changes in activity patterns. Since 2000, we have thus conducted an interdisciplinary study examining the habitual physical activity and health of elderly people living in a medium-sized Japanese town (the Nakanojo Study). In about one-tenth of some 5000 available subjects aged > or =65 years, physical activity has already been assessed continuously for 24 h/day for >8 years using a specially adapted pedometer/accelerometer. This device has a storage capacity of 36 days and can distinguish >10 intensities of physical activity (expressed in metabolic equivalents [METs]). Data have to date been summarized as daily step counts and daily durations of activity of <3 and >3 METs, averaged over a 1-year period. This article provides a detailed overview of both factors influencing habitual physical activity and relationships between such activity and health in an elderly population. To date, analyses have been cross-sectional in type. Substantial associations have been noted between the overall health of participants and both the daily duration of effort undertaken at an intensity of >3 METs and the daily step count. In men, the extent of health is associated more closely with the daily duration of activity of >3 METs than with the daily step count, whereas in women, the association is closer for the step count than for the duration of activity >3 METs

  6. Toothbrush Adaptations.

    ERIC Educational Resources Information Center

    Exceptional Parent, 1987

    1987-01-01

    Suggestions are presented for helping disabled individuals learn to use or adapt toothbrushes for proper dental care. A directory lists dental health instructional materials available from various organizations. (CB)

  7. Attention modulates adaptive motor learning in the 'broken escalator' paradigm.

    PubMed

    Patel, Mitesh; Kaski, Diego; Bronstein, Adolfo M

    2014-07-01

    The physical stumble caused by stepping onto a stationary (broken) escalator represents a locomotor aftereffect (LAE) that attests to a process of adaptive motor learning. Whether such learning is primarily explicit (requiring attention resources) or implicit (independent of attention) is unknown. To address this question, we diverted attention in the adaptation (MOVING) and aftereffect (AFTER) phases of the LAE by loading these phases with a secondary cognitive task (sequential naming of a vegetable, fruit and a colour). Thirty-six healthy adults were randomly assigned to 3 equally sized groups. They performed 5 trials stepping onto a stationary sled (BEFORE), 5 with the sled moving (MOVING) and 5 with the sled stationary again (AFTER). A 'Dual-Task-MOVING (DTM)' group performed the dual-task in the MOVING phase and the 'Dual-Task-AFTEREFFECT (DTAE)' group in the AFTER phase. The 'control' group performed no dual task. We recorded trunk displacement, gait velocity and gastrocnemius muscle EMG of the left (leading) leg. The DTM, but not the DTAE group, had larger trunk displacement during the MOVING phase, and a smaller trunk displacement aftereffect compared with controls. Gait velocity was unaffected by the secondary cognitive task in either group. Thus, adaptive locomotor learning involves explicit learning, whereas the expression of the aftereffect is automatic (implicit). During rehabilitation, patients should be actively encouraged to maintain maximal attention when learning new or challenging locomotor tasks.

  8. STEP Tether Dynamics Preliminary Analysis

    NASA Technical Reports Server (NTRS)

    Glaese, John R.

    2000-01-01

    The General Tethered Object Simulation System (GTOSS) has been successfully converted to the PC environment. GTOSS has been run under Microsoft Windows 95, 98 and NT4.0 with no problems noted. Adaptation to the PC environment and definition of the 3 three body configuration required resizing some of the GTOSS internal data arrays. To allow studies of the tether dynamics accompanying electrodynamic thrust, a tether current flow model has also been developed for GTOSS. This model includes effects due to the earth's magnetic field and ionosphere, tether conductivity, temperature, motion, shape and available power. Sample cases have been defined for a proposed STEP-AIRSEDS (Space Transfer using Electrodynamic Propulsion-The Michigan Technic Corporation proposed tether missions for commercial applications) three body configuration. This required definition of a 6th power scenario for GTOSS. This power scenario allows a user to specify whether orbit raising or orbit lowering is to be performed by selecting the number of the tether. Orbit raising and orbit lowering sample cases have been run successfully. Results from these runs have been included in this report. Results have only been generated so far for a three body configuration. Only point end masses have been represented. No attitude dynamics have been included. Initial results suggest that tether current can have significant and detrimental effects on tether dynamics and provisions will have to be made for control of it. This control will have to be considered in connection with desired target orbits for electrodynamic thrusting, as well as end body attitude control, momentum management of proposed control moment gyros, solar array pointing. All of these items will interact and thus, any system simulation will have to have each of these effects modeled in sufficient detail to display these interactions.

  9. An adaptive grid algorithm for one-dimensional nonlinear equations

    NASA Technical Reports Server (NTRS)

    Gutierrez, William E.; Hills, Richard G.

    1990-01-01

    Richards' equation, which models the flow of liquid through unsaturated porous media, is highly nonlinear and difficult to solve. Step gradients in the field variables require the use of fine grids and small time step sizes. The numerical instabilities caused by the nonlinearities often require the use of iterative methods such as Picard or Newton interation. These difficulties result in large CPU requirements in solving Richards equation. With this in mind, adaptive and multigrid methods are investigated for use with nonlinear equations such as Richards' equation. Attention is focused on one-dimensional transient problems. To investigate the use of multigrid and adaptive grid methods, a series of problems are studied. First, a multigrid program is developed and used to solve an ordinary differential equation, demonstrating the efficiency with which low and high frequency errors are smoothed out. The multigrid algorithm and an adaptive grid algorithm is used to solve one-dimensional transient partial differential equations, such as the diffusive and convective-diffusion equations. The performance of these programs are compared to that of the Gauss-Seidel and tridiagonal methods. The adaptive and multigrid schemes outperformed the Gauss-Seidel algorithm, but were not as fast as the tridiagonal method. The adaptive grid scheme solved the problems slightly faster than the multigrid method. To solve nonlinear problems, Picard iterations are introduced into the adaptive grid and tridiagonal methods. Burgers' equation is used as a test problem for the two algorithms. Both methods obtain solutions of comparable accuracy for similar time increments. For the Burgers' equation, the adaptive grid method finds the solution approximately three times faster than the tridiagonal method. Finally, both schemes are used to solve the water content formulation of the Richards' equation. For this problem, the adaptive grid method obtains a more accurate solution in fewer work units and

  10. Effect of saccadic amplitude adaptation on subsequent adaptation of saccades in different directions.

    PubMed

    Kojima, Yoshiko; Iwamoto, Yoshiki; Yoshida, Kaoru

    2005-12-01

    We have shown previously that adaptation of horizontal saccades exerts facilitating effects on subsequent adaptation of saccades in the same direction. Now we investigated the effect on saccades in different directions. A series of three alternating gain changes was induced by intrasaccadic step (ISS) of the target in two monkeys. The gain of saccades to horizontal or vertical target steps was decreased by backward ISS (conditioning). Then, we used forward ISS to increase their gain back to approximately 1.0. Finally, we induced a gain decrease for saccades to oblique target steps with backward ISS. We analyzed dependency of test adaptation rates on the direction of conditioning saccades. The rate of adaptation of the horizontal component of oblique saccades was significantly larger when conditioned with horizontal saccade adaptation than with vertical saccade adaptation. The rate for the vertical component did not show such differences. Following horizontal saccade adaptation, the horizontal component adapted faster than the vertical component. After vertical saccade adaptation, the vertical component tended to adapt at higher rates. Taken together, the results indicate that horizontal saccade adaptation exerts a facilitating effect on subsequent adaptation of the horizontal component of oblique saccades.

  11. Grid generation and adaptation for the Direct Simulation Monte Carlo Method. [for complex flows past wedges and cones

    NASA Technical Reports Server (NTRS)

    Olynick, David P.; Hassan, H. A.; Moss, James N.

    1988-01-01

    A grid generation and adaptation procedure based on the method of transfinite interpolation is incorporated into the Direct Simulation Monte Carlo Method of Bird. In addition, time is advanced based on a local criterion. The resulting procedure is used to calculate steady flows past wedges and cones. Five chemical species are considered. In general, the modifications result in a reduced computational effort. Moreover, preliminary results suggest that the simulation method is time step dependent if requirements on cell sizes are not met.

  12. Unique characteristics of motor adaptation during walking in young children

    PubMed Central

    Musselman, Kristin E.; Patrick, Susan K.; Vasudevan, Erin V. L.; Bastian, Amy J.

    2011-01-01

    Children show precocious ability in the learning of languages; is this the case with motor learning? We used split-belt walking to probe motor adaptation (a form of motor learning) in children. Data from 27 children (ages 8–36 mo) were compared with those from 10 adults. Children walked with the treadmill belts at the same speed (tied belt), followed by walking with the belts moving at different speeds (split belt) for 8–10 min, followed again by tied-belt walking (postsplit). Initial asymmetries in temporal coordination (i.e., double support time) induced by split-belt walking were slowly reduced, with most children showing an aftereffect (i.e., asymmetry in the opposite direction to the initial) in the early postsplit period, indicative of learning. In contrast, asymmetries in spatial coordination (i.e., center of oscillation) persisted during split-belt walking and no aftereffect was seen. Step length, a measure of both spatial and temporal coordination, showed intermediate effects. The time course of learning in double support and step length was slower in children than in adults. Moreover, there was a significant negative correlation between the size of the initial asymmetry during early split-belt walking (called error) and the aftereffect for step length. Hence, children may have more difficulty learning when the errors are large. The findings further suggest that the mechanisms controlling temporal and spatial adaptation are different and mature at different times. PMID:21368001

  13. The Stepping Stone Approach

    NASA Astrophysics Data System (ADS)

    Brumfitt, A.

    Education is a profession in its own right. It has its own parameters, passions and language. Having the responsibility both of educare and educere, education has a focus of delivering specific factual knowledge whilst drawing out the creative mind. Space Science is a special vehicle having the properties of both educare and educere. It has a magic and wonder that touches the very essence of an individual and his place in time and space; it offers the "wow" factor that all teachers strive for. Space Science is the wrapping paper for other elements in the curriculum, e.g. cross-curricula and skill-based activities, such as language development, creativity, etc. as well as the pure sciences which comprise of engineering, physics and other natural sciences from astronomy to chemistry to biology. Each of these spheres of influence are relevant from kindergarten to undergraduate studies and complement, and in addition support informal education in museums, science centers and the world of e-learning. ESA Science Education has devised the "Stepping Stone Approach" to maximize the greatest outreach to all education stakeholders in Europe. In this paper we illustrate how to best reach these target groups with very specific activities to trigger and sustain enthusiasm whilst supporting the pedagogical, subject content and skill-based needs of a prescribed curriculum.

  14. 1992 STEP Symposium

    NASA Astrophysics Data System (ADS)

    Lui, Tony

    The year 1992 marks the quincentenary jubilee of the famous voyage of Christopher Columbus to the New World, a trip which initiated sustained contact between Europe and the American continent. Courageous explorations often lead to advancement of mankind, be they in uncharted territory or science. As much as Columbus was unaware of what lay in store for his voyage, we were just as poorly informed about what lay beyond our home planet when we began space exploration about three decades ago. There is much similarity among the pioneering spirits characteristic of both endeavors. It is thus fitting to celebrate this quincentenary occasion by declaring 1992 International Space Year (ISY).In conjunction with the COSPAR Meeting and the International Convention of the World Space Congress to be held in Washington, D.C., from August to September 1992, a 4-day symposium on the initial results from the Solar-Terrestrial Energy Program (STEP) Facilities and Theory Campaigns will be held at Johns Hopkins University, Applied Physics Laboratory, Laurel, Md., August 24-27. 1992.

  15. STEPS: JPL's Astrometric Exoplanet Survey

    NASA Technical Reports Server (NTRS)

    Shaklan, Stuart; Pravdo, Steve

    2008-01-01

    Presentation topics include: STEPS ground-based astrometry at Hale Telescope; the instrument; why astronomy and why M-dwarfs; motion of center of light about center of mass in photocentric orbit; photocentric motion vs. fractional mass; high-resolution imaging of STEPS targets; GU 802 p one possible orbit plotted with data, Keplerian frame; GJ 802 results; STEPS future; and a bibliography of STEPS papers.

  16. SPAR-H Step-by-Step Guidance

    SciTech Connect

    April M. Whaley; Dana L. Kelly; Ronald L. Boring; William J. Galyean

    2012-06-01

    Step-by-step guidance was developed recently at Idaho National Laboratory for the US Nuclear Regulatory Commission on the use of the Standardized Plant Analysis Risk-Human Reliability Analysis (SPAR-H) method for quantifying Human Failure Events (HFEs). This work was done to address SPAR-H user needs, specifically requests for additional guidance on the proper application of various aspects of the methodology. This paper overviews the steps of the SPAR-H analysis process and highlights some of the most important insights gained during the development of the step-by-step directions. This supplemental guidance for analysts is applicable when plant-specific information is available, and goes beyond the general guidance provided in existing SPAR-H documentation. The steps highlighted in this paper are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff.

  17. Size Matters

    PubMed Central

    Long, Kimberly; Abuelenen, Toaa; Pava, Libia; Bastille, Maya

    2011-01-01

    We tallied the number of possible mutant amino acids in proteins thought to be inactivated early in tumorigenesis and in proteins thought to be inactivated late in tumorigenesis, respectively. Proteins thought to be inactivated early in tumorigenesis, on average, have a greater number of alternative, mutant possibilities, which raises the possibility that the sequential order of mutations associated with cancer development reflects the random chance, throughout life, of a mutagen inactivating a larger versus a smaller target. The hypothesis that the temporal order of genetic changes in cancer reflects mutagen target sizes leads to novel considerations of 1) the mechanisms of the acquisition of cancer hallmarks and 2) cancer screening strategies. PMID:22701759

  18. On the stability of adaptation process in active noise control systems.

    PubMed

    Ardekani, Iman Tabatabaei; Abdulla, Waleed H

    2011-01-01

    The stability analysis of the adaptation process, performed by the filtered-x least mean square algorithm on weights of active noise controllers, has not been fully investigated. The main contribution of this paper is conducting a theoretical stability analysis for this process without utilizing commonly used simplifying assumptions regarding the secondary electro-acoustic channel. The core of this analysis is based on the root locus theory. The general rules for constructing the root locus plot of the adaptation process are derived by obtaining root locus parameters, including start points, end points, asymptote lines, and breakaway points. The conducted analysis leads to the derivation of a general upper-bound for the adaptation step-size beyond which the mean weight vector of the active noise controller becomes unstable. Also, this analysis yields the optimum step-size for which the adaptive active noise controller has its fastest dynamic performance. The proposed upper-bound and optimum values apply to general secondary electro-acoustic channels, unlike the commonly used ones which apply to only pure delay channels. The results are found to agree very well with those obtained from numerical analyses and computer simulation experiments.

  19. Steps toward lunar settlement

    SciTech Connect

    Jones, E.M.

    1988-01-01

    The costs of transporting people and material to low-earth-orbit (LEO), and thence to the lunar surface, will constrain the pace and pattern of lunar development. Beginning as a spartan ''base camp'' completely supplied from Earth, a lunar science-and-resource-development facility could grow in size, amenities, and capability to the point that passenger transport becomes a major expense. At such a stage, some employees of the facility might be given the opportunity to become permanent residents; and at that point, lunar settlement will have begun. We assume growth rates of facilities and staff contained by the annual delivery of 900 tons to LEO. During the base camp era, about 100 tons would be delivered annually to the lunar surface. Within six years, the facility could grow to a collection of 25 modules, housing a staff of about 16 with each member of the staff serving a six-month tour on a staggered schedule. At the end of this first phase, oxygen produced from lunar ilmenite and delivered to lunar orbit for use as propellant would allow annual lunar-bound cargos of about 200 tons. Production from lunar materials of heat shields for aerobraking would enable economical delivery of lunar oxygen to LEO and, therefore, could raise lunar-bound cargoes to about 450 tons. Accumulatin of production capabilities would eventually allow use of lunar construction materials, to build farms and increase per capita living and working space. Once closed-loop environmental systems are in place, transport costs are dominated by staff rotation and the facility is limited to a maximum staff size of about 300. Further expansion requires that some staff become permanent residents.

  20. Friction of atomically stepped surfaces

    NASA Astrophysics Data System (ADS)

    Dikken, R. J.; Thijsse, B. J.; Nicola, L.

    2017-03-01

    The friction behavior of atomically stepped metal surfaces under contact loading is studied using molecular dynamics simulations. While real rough metal surfaces involve roughness at multiple length scales, the focus of this paper is on understanding friction of the smallest scale of roughness: atomic steps. To this end, periodic stepped Al surfaces with different step geometry are brought into contact and sheared at room temperature. Contact stress that continuously tries to build up during loading, is released with fluctuating stress drops during sliding, according to the typical stick-slip behavior. Stress release occurs not only through local slip, but also by means of step motion. The steps move along the contact, concurrently resulting in normal migration of the contact. The direction of migration depends on the sign of the step, i.e., its orientation with respect to the shearing direction. If the steps are of equal sign, there is a net migration of the entire contact accompanied by significant vacancy generation at room temperature. The stick-slip behavior of the stepped contacts is found to have all the characteristic of a self-organized critical state, with statistics dictated by step density. For the studied step geometries, frictional sliding is found to involve significant atomic rearrangement through which the contact roughness is drastically changed. This leads for certain step configurations to a marked transition from jerky sliding motion to smooth sliding, making the final friction stress approximately similar to that of a flat contact.

  1. Powerlessness Reinterpreted: Reframing Step One.

    ERIC Educational Resources Information Center

    Young, Susan L.

    The 12 steps of the well-known mutual help group, Alcoholics Anonymous (AA), begin with Step One, admitting powerlessness. Although Step One has helped many problem drinkers and other addicts, its spiritual concepts have been criticized. The possibility of reconceptualizing powerlessness as empowering, not only within AA and its offshoot programs,…

  2. SAGE - MULTIDIMENSIONAL SELF-ADAPTIVE GRID CODE

    NASA Technical Reports Server (NTRS)

    Davies, C. B.

    1994-01-01

    acceptable since it makes possible an overall and local error reduction through grid redistribution. SAGE includes the ability to modify the adaption techniques in boundary regions, which substantially improves the flexibility of the adaptive scheme. The vectorial approach used in the analysis also provides flexibility. The user has complete choice of adaption direction and order of sequential adaptions without concern for the computational data structure. Multiple passes are available with no restraint on stepping directions; for each adaptive pass the user can choose a completely new set of adaptive parameters. This facility, combined with the capability of edge boundary control, enables the code to individually adapt multi-dimensional multiple grids. Zonal grids can be adapted while maintaining continuity along the common boundaries. For patched grids, the multiple-pass capability enables complete adaption. SAGE is written in FORTRAN 77 and is intended to be machine independent; however, it requires a FORTRAN compiler which supports NAMELIST input. It has been successfully implemented on Sun series computers, SGI IRIS's, DEC MicroVAX computers, HP series computers, the Cray YMP, and IBM PC compatibles. Source code is provided, but no sample input and output files are provided. The code reads three datafiles: one that contains the initial grid coordinates (x,y,z), one that contains corresponding flow-field variables, and one that contains the user control parameters. It is assumed that the first two datasets are formatted as defined in the plotting software package PLOT3D. Several machine versions of PLOT3D are available from COSMIC. The amount of main memory is dependent on the size of the matrix. The standard distribution medium for SAGE is a 5.25 inch 360K MS-DOS format diskette. It is also available on a .25 inch streaming magnetic tape cartridge in UNIX tar format or on a 9-track 1600 BPI ASCII CARD IMAGE format magnetic tape. SAGE was developed in 1989, first

  3. Bacterial surface adaptation

    NASA Astrophysics Data System (ADS)

    Utada, Andrew

    2014-03-01

    Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

  4. Multiple-time-stepping generalized hybrid Monte Carlo methods

    SciTech Connect

    Escribano, Bruno; Akhmatskaya, Elena; Reich, Sebastian; Azpiroz, Jon M.

    2015-01-01

    Performance of the generalized shadow hybrid Monte Carlo (GSHMC) method [1], which proved to be superior in sampling efficiency over its predecessors [2–4], molecular dynamics and hybrid Monte Carlo, can be further improved by combining it with multi-time-stepping (MTS) and mollification of slow forces. We demonstrate that the comparatively simple modifications of the method not only lead to better performance of GSHMC itself but also allow for beating the best performed methods, which use the similar force splitting schemes. In addition we show that the same ideas can be successfully applied to the conventional generalized hybrid Monte Carlo method (GHMC). The resulting methods, MTS-GHMC and MTS-GSHMC, provide accurate reproduction of thermodynamic and dynamical properties, exact temperature control during simulation and computational robustness and efficiency. MTS-GHMC uses a generalized momentum update to achieve weak stochastic stabilization to the molecular dynamics (MD) integrator. MTS-GSHMC adds the use of a shadow (modified) Hamiltonian to filter the MD trajectories in the HMC scheme. We introduce a new shadow Hamiltonian formulation adapted to force-splitting methods. The use of such Hamiltonians improves the acceptance rate of trajectories and has a strong impact on the sampling efficiency of the method. Both methods were implemented in the open-source MD package ProtoMol and were tested on a water and a protein systems. Results were compared to those obtained using a Langevin Molly (LM) method [5] on the same systems. The test results demonstrate the superiority of the new methods over LM in terms of stability, accuracy and sampling efficiency. This suggests that putting the MTS approach in the framework of hybrid Monte Carlo and using the natural stochasticity offered by the generalized hybrid Monte Carlo lead to improving stability of MTS and allow for achieving larger step sizes in the simulation of complex systems.

  5. Steps toward fault-tolerant quantum chemistry.

    SciTech Connect

    Taube, Andrew Garvin

    2010-05-01

    MPI alone is insufficient to achieve parallel scaling; QC developers have been forced to use alternative approaches to achieve scalability and would be receptive to radical shifts in the programming paradigm. Initial work in adapting the simplest QC method, Hartree-Fock, to this the new programming model indicates that the approach is beneficial for QC applications. However, the advantages to being able to scale to exascale computers are greatest for the computationally most expensive algorithms; within QC these are the high-accuracy coupled-cluster (CC) methods. Parallel coupledcluster programs are available, however they are based on the conventional MPI paradigm. Much of the effort is spent handling the complicated data dependencies between the various processors, especially as the size of the problem becomes large. The current paradigm will not survive the move to exascale computers. Here we discuss the initial steps toward designing and implementing a CC method within this model. First, we introduce the general concepts behind a CC method, focusing on the aspects that make these methods difficult to parallelize with conventional techniques. Then we outline what is the computational core of the CC method - a matrix multiply - within the task-based approach that the FAST-OS project is designed to take advantage of. Finally we outline the general setup to implement the simplest CC method in this model, linearized CC doubles (LinCC).

  6. Adaptive management

    USGS Publications Warehouse

    Allen, Craig R.; Garmestani, Ahjond S.

    2015-01-01

    Adaptive management is an approach to natural resource management that emphasizes learning through management where knowledge is incomplete, and when, despite inherent uncertainty, managers and policymakers must act. Unlike a traditional trial and error approach, adaptive management has explicit structure, including a careful elucidation of goals, identification of alternative management objectives and hypotheses of causation, and procedures for the collection of data followed by evaluation and reiteration. The process is iterative, and serves to reduce uncertainty, build knowledge and improve management over time in a goal-oriented and structured process.

  7. On Bayesian adaptive video super resolution.

    PubMed

    Liu, Ce; Sun, Deqing

    2014-02-01

    Although multiframe super resolution has been extensively studied in past decades, super resolving real-world video sequences still remains challenging. In existing systems, either the motion models are oversimplified or important factors such as blur kernel and noise level are assumed to be known. Such models cannot capture the intrinsic characteristics that may differ from one sequence to another. In this paper, we propose a Bayesian approach to adaptive video super resolution via simultaneously estimating underlying motion, blur kernel, and noise level while reconstructing the original high-resolution frames. As a result, our system not only produces very promising super resolution results outperforming the state of the art, but also adapts to a variety of noise levels and blur kernels. To further analyze the effect of noise and blur kernel, we perform a two-step analysis using the Cramer-Rao bounds. We study how blur kernel and noise influence motion estimation with aliasing signals, how noise affects super resolution with perfect motion, and finally how blur kernel and noise influence super resolution with unknown motion. Our analysis results confirm empirical observations, in particular that an intermediate size blur kernel achieves the optimal image reconstruction results.

  8. On Bayesian Adaptive Video Super Resolution.

    PubMed

    Liu, Ce; Sun, Deqing

    2013-06-26

    Although multi-frame super resolution has been extensively studied in past decades, super resolving real-world video sequences still remains challenging. In existing systems, either the motion models are oversimplified, or important factors such as blur kernel and noise level are assumed to be known. Such models cannot capture the intrinsic characteristics that may differ from one sequence to another. In this paper, we propose a Bayesian approach to adaptive video super resolution via simultaneously estimating underlying motion, blur kernel and noise level while reconstructing the original high-res frames. As a result, our system not only produces very promising super resolution results outperforming the state of the art, but also adapts to a variety of noise levels and blur kernels. To further analyze the effect of noise and blur kernel, we perform a two-step analysis using the Cramer-Rao bounds. We study how blur kernel and noise influence motion estimation with aliasing signals, how noise affects super resolution with perfect motion, and finally how blur kernel and noise influence super resolution with unknown motion. Our analysis results confirm empirical observations, in particular that an intermediate size blur kernel achieves the optimal image reconstruction results.

  9. [The adaptive-compensatory reactions in adjusting to space flights].

    PubMed

    Volozhin, A I

    1995-01-01

    In this paper an evolutionary approach is used to substantiate the steps of life evolution on Earth towards overcoming the gravitational forces with the formation of metabolic cycles controlling the energetic of anti-G processes. The step of an adaptation to hypogravity was similar to return of surface animals to an aquatic environment. The impossibility of coming back to land was the "price" of adaptation to the aquatic environment. This phenomenon was used by the author as a logical model of human adaptation to a weightless environment. The concept of adaptation is examined from two points of view: adaptation and compensation. The scheme contains 4 steps of adaptation to space mission environments: Step I-preadaptation (phase of primary reactions); Step II-compensation of body structures not being in line with the conditions of a novel environment; Step III-the formation of parameters of an organism corresponding to the norm of adaptation to weightlessness; Step IV-the return of cosmonauts to Earth under hypergravity conditions. In compliance with these steps we consider the tasks of supporting space missions to facilitate body readaptation after return to Earth, i.e., to decrease the "price" of adaptation.

  10. Practical and low cost whole-organism motility assay: A step-by-step protocol.

    PubMed

    Preston, Sarah; Jabbar, Abdul; Nowell, Cameron; Joachim, Anja; Ruttkowski, Baerbel; Cardno, Tony; Hofmann, Andreas; Gasser, Robin B

    2016-02-01

    Here, we provide a step-by-step protocol for a practical and low cost whole-organism assay for the screening of chemical compounds for activity against parasitic worms. This assay has considerable advantages over conventional methods, mainly in relation to ease of use, throughput, time and cost. It is readily suited to the screening of hundreds to thousands of compounds for subsequent hit-to-lead optimisation, and should be applicable to many different parasites and other organisms commensurate with the size of wells in the microtiter plates used for phenotypic screening.

  11. An hp-adaptivity and error estimation for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Bey, Kim S.

    1995-01-01

    This paper presents an hp-adaptive discontinuous Galerkin method for linear hyperbolic conservation laws. A priori and a posteriori error estimates are derived in mesh-dependent norms which reflect the dependence of the approximate solution on the element size (h) and the degree (p) of the local polynomial approximation. The a posteriori error estimate, based on the element residual method, provides bounds on the actual global error in the approximate solution. The adaptive strategy is designed to deliver an approximate solution with the specified level of error in three steps. The a posteriori estimate is used to assess the accuracy of a given approximate solution and the a priori estimate is used to predict the mesh refinements and polynomial enrichment needed to deliver the desired solution. Numerical examples demonstrate the reliability of the a posteriori error estimates and the effectiveness of the hp-adaptive strategy.

  12. Control Software for Piezo Stepping Actuators

    NASA Technical Reports Server (NTRS)

    Shields, Joel F.

    2013-01-01

    A control system has been developed for the Space Interferometer Mission (SIM) piezo stepping actuator. Piezo stepping actuators are novel because they offer extreme dynamic range (centimeter stroke with nanometer resolution) with power, thermal, mass, and volume advantages over existing motorized actuation technology. These advantages come with the added benefit of greatly reduced complexity in the support electronics. The piezo stepping actuator consists of three fully redundant sets of piezoelectric transducers (PZTs), two sets of brake PZTs, and one set of extension PZTs. These PZTs are used to grasp and move a runner attached to the optic to be moved. By proper cycling of the two brake and extension PZTs, both forward and backward moves of the runner can be achieved. Each brake can be configured for either a power-on or power-off state. For SIM, the brakes and gate of the mechanism are configured in such a manner that, at the end of the step, the actuator is in a parked or power-off state. The control software uses asynchronous sampling of an optical encoder to monitor the position of the runner. These samples are timed to coincide with the end of the previous move, which may consist of a variable number of steps. This sampling technique linearizes the device by avoiding input saturation of the actuator and makes latencies of the plant vanish. The software also estimates, in real time, the scale factor of the device and a disturbance caused by cycling of the brakes. These estimates are used to actively cancel the brake disturbance. The control system also includes feedback and feedforward elements that regulate the position of the runner to a given reference position. Convergence time for smalland medium-sized reference positions (less than 200 microns) to within 10 nanometers can be achieved in under 10 seconds. Convergence times for large moves (greater than 1 millimeter) are limited by the step rate.

  13. Adaptive Thresholds

    SciTech Connect

    Bremer, P. -T.

    2014-08-26

    ADAPT is a topological analysis code that allow to compute local threshold, in particular relevance based thresholds for features defined in scalar fields. The initial target application is vortex detection but the software is more generally applicable to all threshold based feature definitions.

  14. Step-gradient capillary electrochromatography.

    PubMed

    Euerby, M R; Gilligan, D; Johnson, C M; Bartle, K D

    1997-10-01

    The analytical benefits of using a step-gradient in capillary electrochromatography (CEC) are demonstrated. The application of step-gradient CEC to the analysis of six diuretics of widely differing lipophilicities was evaluated and shown to result in a marked reduction in the analysis time and an improvement in the peak shape for later-eluting lipophilic components. When the step-gradient approach was performed in an automated mode, the retention time RSD for repeated injections was below 1%.

  15. Adaptation of adaptive optics systems.

    NASA Astrophysics Data System (ADS)

    Xin, Yu; Zhao, Dazun; Li, Chen

    1997-10-01

    In the paper, a concept of an adaptation of adaptive optical system (AAOS) is proposed. The AAOS has certain real time optimization ability against the variation of the brightness of detected objects m, atmospheric coherence length rO and atmospheric time constant τ by means of changing subaperture number and diameter, dynamic range, and system's temporal response. The necessity of AAOS using a Hartmann-Shack wavefront sensor and some technical approaches are discussed. Scheme and simulation of an AAOS with variable subaperture ability by use of both hardware and software are presented as an example of the system.

  16. Step by Step to Smoke-Free Schools.

    ERIC Educational Resources Information Center

    VanSciver, James H.; Roberts, H. Earl

    1989-01-01

    This ERIC digest discusses ways of effectively banning smoking in schools so that controversies do not continue after implementation of the policy. By advocating a process approach, the document cites steps taken by the Lake Forest School Board to prohibit smoking in and around school grounds. Step one involved committee planning involving…

  17. Step-by-Step Visual Manuals: Design and Development

    ERIC Educational Resources Information Center

    Urata, Toshiyuki

    2004-01-01

    The types of handouts and manuals that are used in technology training vary. Some describe procedures in a narrative way without graphics; some employ step-by-step instructions with screen captures. According to Thirlway (1994), a training manual should be like a tutor that permits a student to learn at his own pace and gives him confidence for…

  18. Preface, Soil Science: A step-by-step analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book provides step-by-step procedures for soil professionals, without a lot of background theory. Chapters are targeted toward agricultural and environmental consultants, producers, students, teachers, government, and industry. Applied soil scientists gave input through a survey, which guided t...

  19. Leading Change Step-by-Step: Tactics, Tools, and Tales

    ERIC Educational Resources Information Center

    Spiro, Jody

    2010-01-01

    "Leading Change Step-by-Step" offers a comprehensive and tactical guide for change leaders. Spiro's approach has been field-tested for more than a decade and proven effective in a wide variety of public sector organizations including K-12 schools, universities, international agencies and non-profits. The book is filled with proven tactics for…

  20. Variable time-stepping in the pathwise numerical solution of the chemical Langevin equation.

    PubMed

    Ilie, Silvana

    2012-12-21

    Stochastic modeling is essential for an accurate description of the biochemical network dynamics at the level of a single cell. Biochemically reacting systems often evolve on multiple time-scales, thus their stochastic mathematical models manifest stiffness. Stochastic models which, in addition, are stiff and computationally very challenging, therefore the need for developing effective and accurate numerical methods for approximating their solution. An important stochastic model of well-stirred biochemical systems is the chemical Langevin Equation. The chemical Langevin equation is a system of stochastic differential equation with multidimensional non-commutative noise. This model is valid in the regime of large molecular populations, far from the thermodynamic limit. In this paper, we propose a variable time-stepping strategy for the numerical solution of a general chemical Langevin equation, which applies for any level of randomness in the system. Our variable stepsize method allows arbitrary values of the time-step. Numerical results on several models arising in applications show significant improvement in accuracy and efficiency of the proposed adaptive scheme over the existing methods, the strategies based on halving/doubling of the stepsize and the fixed step-size ones.

  1. Effects of an aft facing step on the surface of a laminar flow glider wing

    NASA Technical Reports Server (NTRS)

    Sandlin, Doral R.; Saiki, Neal

    1993-01-01

    A motor glider was used to perform a flight test study on the effects of aft facing steps in a laminar boundary layer. This study focuses on two dimensional aft facing steps oriented spanwise to the flow. The size and location of the aft facing steps were varied in order to determine the critical size that will force premature transition. Transition over a step was found to be primarily a function of Reynolds number based on step height. Both of the step height Reynolds numbers for premature and full transition were determined. A hot film anemometry system was used to detect transition.

  2. Change of ruminal sodium transport in sheep during dietary adaptation.

    PubMed

    Etschmann, Benjamin; Suplie, Annabelle; Martens, Holger

    2009-02-01

    Rumen adaptation plays an important role in the productive cycle of dairy cattle. In this study, the time course of functional rumen epithelium adaptation after a change from hay feeding (ad libitum) to a mixed hay/concentrate diet was monitored by measuring Na+ transport rates in Ussing chamber experiments. A total of 18 sheep were subjected to different periods of mixed hay/concentrate feeding ranging from 0 weeks (control; hay ad libitum) to 12 weeks (800 g hay plus 800 g concentrate per day in two equal portions). For each animal, the net absorption of sodium was measured following the mixed hay/concentrate feeding period. Net Na transport, Jnet, significantly rose from 2.15 +/- 0.43 (control) to 3.73 +/- 1.02 microeq x cm(-2) x h(-1) after one week of mixed hay/ concentrate diet, reached peak levels of 4.55 +/- 0.50 microEq x cm(-2) x h(-1) after four weeks and levelled out at 3.92 +/- 0.36 microeq x cm(-2) x h(-1) after 12 weeks of mixed feeding. Thus, 73% of functional adaptation occurred during the first week after diet change. This is in apparent contrast to findings that morphological adaptation takes approximately six weeks to reach peak levels. Hence, early functional adaptation to a mixed hay/concentrate diet is characterised by enhanced Na absorption rates per epithelial cell. Absorption rates are likely to be further enhanced by proliferative effects on the rumen epithelium (number and size of papillae) when concentrate diets are fed over longer periods of time. Early functional adaptation without surface area enlargement of the rumen epithelium appears to be the first step in coping with altered fermentation rates following diet change.

  3. Premotor inhibitory neurons carry signals related to saccade adaptation in the monkey.

    PubMed

    Kojima, Yoshiko; Iwamoto, Yoshiki; Robinson, Farrel R; Noto, Christopher T; Yoshida, Kaoru

    2008-01-01

    Cerebellar output changes during motor learning. How these changes cause alterations of motoneuron activity and movement remains an unresolved question for voluntary movements. To answer this question, we examined premotor neurons for saccadic eye movement. Previous studies indicate that cells in the fastigial oculomotor region (FOR) within the cerebellar nuclei on one side exhibit a gradual increase in their saccade-related discharge as the amplitude of ipsiversive saccades adaptively decreases. This change in FOR activity could cause the adaptive change in saccade amplitude because neurons in the FOR project directly to the brain stem region containing premotor burst neurons (BNs). To test this possibility, we recorded the activity of saccade-related burst neurons in the area that houses premotor inhibitory burst neurons (IBNs) and examined their discharge during amplitude-reducing adaptation elicited by intrasaccadic target steps. We specifically analyzed their activity for off-direction (contraversive) saccades, in which the IBN activity would increase to reduce saccade size. Before adaptation, 29 of 42 BNs examined discharged, at least occasionally, for contraversive saccades. As the amplitude of contraversive saccades decreased adaptively, half of BNs with off-direction spike activity showed an increase in the number of spikes (14/29) or an earlier occurrence of spikes (7/14). BNs that were silent during off-direction saccades before adaptation remained silent after adaptation. These results indicate that the changes in the off-direction activity of BNs are closely related to adaptive changes in saccade size and are appropriate to cause these changes.

  4. Flow Focusing: a versatile technology to produce size-controlled and specific-morphology microparticles.

    PubMed

    Martín-Banderas, Lucía; Flores-Mosquera, María; Riesco-Chueca, Pascual; Rodríguez-Gil, Alfonso; Cebolla, Angel; Chávez, Sebastián; Gañán-Calvo, Alfonso M

    2005-07-01

    The Flow Focusing platform is especially advantageous for micro- and nanoparticle production. This versatile technique is amenable to designing the size, surface treatment and internal topology of the particles; mechanical stresses are minimal-an optimal feature for the manipulation of delicate substances. Multiplexing and high-rate production are readily implemented. Adaptive operational design can lead, in one single step, to finely tuned microcapsules encasing different products within a targeted morphology. This achievement is of great significance for most microcapsule applications in the biosciences (for example, drug delivery, cell encapsulation, and the production of bead arrays).

  5. Adaptation Forestry in Minnesota's Northwoods

    NASA Astrophysics Data System (ADS)

    Cornett, M.; White, M.; Etterson, J.; Kavajecz, L.; Mead, J.; Handler, S.; Swanston, C.; Hall, K.

    2014-12-01

    Forest restoration and management goals are shifting in northern Minnesota in light of new information on climate trends. Adaptation forestry encompasses a combination of practices designed to favor native populations and species likely to persist under warmer, drier conditions. The overarching project goal is to increase the adaptive capacity of northern forests such that they continue to sustain a variety of services, including carbon sequestration, fiber production, watershed protection, and wildlife habitat. We are currently testing the feasibility and efficacy of adaptation forestry in the northern Great Lakes region in three common forest types: Boreal-Mixed, Pine, and Hardwoods. 12 sites (2,000 acres total) recently subjected to a range of structural treatments (gap creation, shelterwood, and clear-cut with reserves) were coupled with "adaptation plantings" of species that are likely to thrive under changed climate conditions (e.g., red oak, bur oak, white pine). Seedlings, ~110,000 total, originated from two source locations, one that reflects current adaptation to the climate of northern Minnesota and another from a more southern source in central Minnesota. To date, we have assessed results from two growing seasons by tracking survival, growth and phenological characteristics of planted seedlings. This project is a first step in determining whether adaptation management can be used as a tool to help northern forests transition to an uncertain future. Cooperation with state, federal, and academic partners may ultimately influence the adaptive capacity across millions of acres in the Great Lakes region.

  6. Adaptive Dynamic Bayesian Networks

    SciTech Connect

    Ng, B M

    2007-10-26

    A discrete-time Markov process can be compactly modeled as a dynamic Bayesian network (DBN)--a graphical model with nodes representing random variables and directed edges indicating causality between variables. Each node has a probability distribution, conditional on the variables represented by the parent nodes. A DBN's graphical structure encodes fixed conditional dependencies between variables. But in real-world systems, conditional dependencies between variables may be unknown a priori or may vary over time. Model errors can result if the DBN fails to capture all possible interactions between variables. Thus, we explore the representational framework of adaptive DBNs, whose structure and parameters can change from one time step to the next: a distribution's parameters and its set of conditional variables are dynamic. This work builds on recent work in nonparametric Bayesian modeling, such as hierarchical Dirichlet processes, infinite-state hidden Markov networks and structured priors for Bayes net learning. In this paper, we will explain the motivation for our interest in adaptive DBNs, show how popular nonparametric methods are combined to formulate the foundations for adaptive DBNs, and present preliminary results.

  7. Adaptive equalization

    NASA Astrophysics Data System (ADS)

    Qureshi, S. U. H.

    1985-09-01

    Theoretical work which has been effective in improving data transmission by telephone and radio links using adaptive equalization (AE) techniques is reviewed. AE has been applied to reducing the temporal dispersion effects, such as intersymbol interference, caused by the channel accessed. Attention is given to the Nyquist telegraph transmission theory, least mean square error adaptive filtering and the theory and structure of linear receive and transmit filters for reducing error. Optimum nonlinear receiver structures are discussed in terms of optimality criteria as a function of error probability. A suboptimum receiver structure is explored in the form of a decision-feedback equalizer. Consideration is also given to quadrature amplitude modulation and transversal equalization for receivers.

  8. Connector adapter

    NASA Technical Reports Server (NTRS)

    Hacker, Scott C. (Inventor); Dean, Richard J. (Inventor); Burge, Scott W. (Inventor); Dartez, Toby W. (Inventor)

    2007-01-01

    An adapter for installing a connector to a terminal post, wherein the connector is attached to a cable, is presented. In an embodiment, the adapter is comprised of an elongated collet member having a longitudinal axis comprised of a first collet member end, a second collet member end, an outer collet member surface, and an inner collet member surface. The inner collet member surface at the first collet member end is used to engage the connector. The outer collet member surface at the first collet member end is tapered for a predetermined first length at a predetermined taper angle. The collet includes a longitudinal slot that extends along the longitudinal axis initiating at the first collet member end for a predetermined second length. The first collet member end is formed of a predetermined number of sections segregated by a predetermined number of channels and the longitudinal slot.

  9. Adaptive manifold learning.

    PubMed

    Zhang, Zhenyue; Wang, Jing; Zha, Hongyuan

    2012-02-01

    Manifold learning algorithms seek to find a low-dimensional parameterization of high-dimensional data. They heavily rely on the notion of what can be considered as local, how accurately the manifold can be approximated locally, and, last but not least, how the local structures can be patched together to produce the global parameterization. In this paper, we develop algorithms that address two key issues in manifold learning: 1) the adaptive selection of the local neighborhood sizes when imposing a connectivity structure on the given set of high-dimensional data points and 2) the adaptive bias reduction in the local low-dimensional embedding by accounting for the variations in the curvature of the manifold as well as its interplay with the sampling density of the data set. We demonstrate the effectiveness of our methods for improving the performance of manifold learning algorithms using both synthetic and real-world data sets.

  10. 6 Steps to a Solution.

    ERIC Educational Resources Information Center

    LeTendre, Brenda Guenther

    2000-01-01

    Getting answers to questions about schools and student learning requires that educators know how to collect, analyze, and interpret data. Six critical steps in this process include: posing questions, establishing judgment criteria, making a plan, gathering data, analyzing data, and interpreting results. These steps can serve as a beginning guide…

  11. Physical modeling of stepped spillways

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stepped spillways applied to embankment dams are becoming popular for addressing the rehabilitation of aging watershed dams, especially those situated in the urban landscape. Stepped spillways are typically placed over the existing embankment, which provides for minimal disturbance to the original ...

  12. Adaptive sampler

    DOEpatents

    Watson, B.L.; Aeby, I.

    1980-08-26

    An adaptive data compression device for compressing data is described. The device has a frequency content, including a plurality of digital filters for analyzing the content of the data over a plurality of frequency regions, a memory, and a control logic circuit for generating a variable rate memory clock corresponding to the analyzed frequency content of the data in the frequency region and for clocking the data into the memory in response to the variable rate memory clock.

  13. Adaptive antennas

    NASA Astrophysics Data System (ADS)

    Barton, P.

    1987-04-01

    The basic principles of adaptive antennas are outlined in terms of the Wiener-Hopf expression for maximizing signal to noise ratio in an arbitrary noise environment; the analogy with generalized matched filter theory provides a useful aid to understanding. For many applications, there is insufficient information to achieve the above solution and thus non-optimum constrained null steering algorithms are also described, together with a summary of methods for preventing wanted signals being nulled by the adaptive system. The three generic approaches to adaptive weight control are discussed; correlation steepest descent, weight perturbation and direct solutions based on sample matrix conversion. The tradeoffs between hardware complexity and performance in terms of null depth and convergence rate are outlined. The sidelobe cancellor technique is described. Performance variation with jammer power and angular distribution is summarized and the key performance limitations identified. The configuration and performance characteristics of both multiple beam and phase scan array antennas are covered, with a brief discussion of performance factors.

  14. Leidenfrost Drop on a Step

    NASA Astrophysics Data System (ADS)

    Lagubeau, Guillaume; Le Merrer, Marie; Clanet, Christophe; Quere, David

    2008-11-01

    When deposited on a hot plate, a water droplet evaporates quickly. However, a vapor film appears under the drop above a critical temperature, called Leidenfrost temperature, which insulates the drop from its substrate. Linke & al (2006) reported a spontaneous movement of such a drop, when deposited on a ratchet. We study here the case of a flat substrate decorated with a single micrometric step. The drop is deposited on the lower part of the plate and pushed towards the step at small constant velocity. If the kinetic energy of the drop is sufficient, it can climb up the step. In that case, depending on the substrate temperature, the drop can either be decelerated or accelerated by the step. We try to understand the dynamics of these drops, especially the regime where they accelerate. Taking advantage of this phenomenon, we could then build a multiple-step setup, making it possible for a Leidenfrost drop to climb stairs.

  15. A Step-by-Step Clinical Approach for the Management of Neuroendocrine Tumours.

    PubMed

    Yordanova, A; Ahmadzadehfar, H; Gonzalez-Carmona, M; Strassburg, C; Mayer, K; Feldmann, G; Schmidt-Wolf, I; Lingohr, P; Fischer, S; Kristiansen, G; Essler, M

    2017-02-01

    Neuroendocrine tumours (NET) are rare neoplasms, but the incidence is permanently increasing. Most of the NETs are slow proliferating and clinically silent, and for that reason, they are often diagnosed at a stage with advanced disease. The complexity and diversity of the NET-biology require the treatment of patients in specialised centres to guarantee a qualified, multidisciplinary treatment planning. At our institution, we developed an interdisciplinary model for the assessment and treatment of NET. The aim was to adapt the guidelines to the clinical practice, exchange of current knowledge, and a tailored approach to the individual patient. In our team are included medical professionals from pathology, radiology, oncology, gastroenterology, oncological surgery, and nuclear medicine. In this paper, we describe step-by-step a procedural algorithm for the management of patients with neuroendocrine tumours, focusing on midgut-NETs in terms of therapy.

  16. Luminosity progression in dart-stepped leader step formation

    NASA Astrophysics Data System (ADS)

    Wang, D.; Takagi, N.; Uman, M. A.; Jordan, D. M.

    2016-12-01

    Using a high-speed optical imaging system, we have observed the step formation bright pulse discharges occurring at the tip of dart-stepped leaders of rocket triggered lightning with a time resolution of 0.1 µs and a spatial resolution of about 1.4 m. Each of the step formation pulse discharges appeared to initiate at a location immediately below the bottom of its previous pulse discharge and to propagate in bidirectional (upward and downward) waves with a speed on the order of 107 m/s. The downward waves of the pulse discharges tended to slow down significantly after they propagated a distance of about 2 m. Based on the results observed in this study and those published in literatures, we propose a conceptual view of leader step formation.

  17. Continuous versus step-by-step scanning mode of a novel 3D scanner for CyberKnife measurements.

    PubMed

    Al Kafi, M Abdullah; Mwidu, Umar; Moftah, Belal

    2015-11-01

    The purpose of the study is to investigate the continuous versus step-by-step scanning mode of a commercial circular 3D scanner for commissioning measurements of a robotic stereotactic radiosurgery system. The 3D scanner was used for profile measurements in step-by-step and continuous modes with the intent of comparing the two scanning modes for consistency. The profile measurements of in-plane, cross-plane, 15 degree, and 105 degree were performed for both fixed cones and Iris collimators at depth of maximum dose and at 10cm depth. For CyberKnife field size, penumbra, flatness and symmetry analysis, it was observed that the measurements with continuous mode, which can be up to 6 times faster than step-by-step mode, are comparable and produce scans nearly identical to step-by-step mode. When compared with centered step-by-step mode data, a fully processed continuous mode data gives rise to maximum of 0.50% and 0.60% symmetry and flatness difference respectfully for all the fixed cones and Iris collimators studied.

  18. The NIST Step Class Library (Step Into the Future)

    DTIC Science & Technology

    1990-09-01

    Katherine C. Morris (kc@cme.nist.gov) Factory Automation System Division National Institute of Standards and Technology "Any meaningful exchange of...Industrial Automation Systems (1C 184) Subcommittee on Manufacturing Data and Languages (SC4).[NCGA90] [Smith89] 2. The Omnibus Trade Act of 1988 changed the...Figure 6. Excerpt from a STEP exclange file based on the Geometry model 1be NIST STEP Class Libary Page 13 An issue of concern in this

  19. Step-by-step growth of complex oxide microstructures

    SciTech Connect

    Datskos, Panos G.; Cullen, David A.; Sharma, Jaswinder K.

    2015-06-10

    The synthesis of complex and hybrid oxide microstructures is of fundamental interest and practical applications. However, the design and synthesis of such structures is a challenging task. We developed a solution phase process to synthesize complex silica and silica titania hybrid microstructures by exploiting the emulsion droplet based shape control and step by step growth. The strategy is robust and can be extended to make complex hybrid structures made of two or more materials while each having its own shape.

  20. Dynamically optimized Wang-Landau sampling with adaptive trial moves and modification factors.

    PubMed

    Koh, Yang Wei; Lee, Hwee Kuan; Okabe, Yutaka

    2013-11-01

    The density of states of continuous models is known to span many orders of magnitudes at different energies due to the small volume of phase space near the ground state. Consequently, the traditional Wang-Landau sampling which uses the same trial move for all energies faces difficulties sampling the low-entropic states. We developed an adaptive variant of the Wang-Landau algorithm that very effectively samples the density of states of continuous models across the entire energy range. By extending the acceptance ratio method of Bouzida, Kumar, and Swendsen such that the step size of the trial move and acceptance rate are adapted in an energy-dependent fashion, the random walker efficiently adapts its sampling according to the local phase space structure. The Wang-Landau modification factor is also made energy dependent in accordance with the step size, enhancing the accumulation of the density of states. Numerical simulations show that our proposed method performs much better than the traditional Wang-Landau sampling.

  1. Speech perception at positive signal-to-noise ratios using adaptive adjustment of time compression.

    PubMed

    Schlueter, Anne; Brand, Thomas; Lemke, Ulrike; Nitzschner, Stefan; Kollmeier, Birger; Holube, Inga

    2015-11-01

    Positive signal-to-noise ratios (SNRs) characterize listening situations most relevant for hearing-impaired listeners in daily life and should therefore be considered when evaluating hearing aid algorithms. For this, a speech-in-noise test was developed and evaluated, in which the background noise is presented at fixed positive SNRs and the speech rate (i.e., the time compression of the speech material) is adaptively adjusted. In total, 29 younger and 12 older normal-hearing, as well as 24 older hearing-impaired listeners took part in repeated measurements. Younger normal-hearing and older hearing-impaired listeners conducted one of two adaptive methods which differed in adaptive procedure and step size. Analysis of the measurements with regard to list length and estimation strategy for thresholds resulted in a practical method measuring the time compression for 50% recognition. This method uses time-compression adjustment and step sizes according to Versfeld and Dreschler [(2002). J. Acoust. Soc. Am. 111, 401-408], with sentence scoring, lists of 30 sentences, and a maximum likelihood method for threshold estimation. Evaluation of the procedure showed that older participants obtained higher test-retest reliability compared to younger participants. Depending on the group of listeners, one or two lists are required for training prior to data collection.

  2. Being Prepared for Climate Change: Checklists of Potential Climate Change Risks, from Step 3

    EPA Pesticide Factsheets

    The Being Prepared for Climate Change workbook is a guide for constructing a climate change adaptation plan based on identifying risks and their consequences. These checklists (from Step 3 of the workbook) help users identify risks.

  3. A fully implicit, fully adaptive time and space discretisation method for phase-field simulation of binary alloy solidification

    NASA Astrophysics Data System (ADS)

    Rosam, J.; Jimack, P. K.; Mullis, A.

    2007-08-01

    A fully implicit numerical method based upon adaptively refined meshes for the simulation of binary alloy solidification in 2D is presented. In addition we combine a second-order fully implicit time discretisation scheme with variable step size control to obtain an adaptive time and space discretisation method. The superiority of this method, compared to widely used fully explicit methods, with respect to CPU time and accuracy, is shown. Due to the high nonlinearity of the governing equations a robust and fast solver for systems of nonlinear algebraic equations is needed to solve the intermediate approximations per time step. We use a nonlinear multigrid solver which shows almost h-independent convergence behaviour.

  4. 7 Steps to Aging Well

    MedlinePlus

    ... Issue Past Issues Special Section 7 Steps to Aging Well Past Issues / Winter 2007 Table of Contents ... Exercise: A Guide from the National Institute on Aging is a publication from NIA that has strength, ...

  5. Adaptive walking in Alzheimer's disease.

    PubMed

    Orcioli-Silva, Diego; Simieli, Lucas; Barbieri, Fabio Augusto; Stella, Florindo; Gobbi, Lilian Teresa Bucken

    2012-01-01

    The aim of this study is to analyze dual-task effects on free and adaptive gait in Alzheimer's disease (AD) patients. Nineteen elders with AD participated in the study. A veteran neuropsychiatrist established the degree of AD in the sample. To determine dual-task effects on free and adaptive gait, patients performed five trials for each experimental condition: free and adaptive gait with and without a dual-task (regressive countdown). Spatial and temporal parameters were collected through an optoelectronic tridimensional system. The central stride was analyzed in free gait, and the steps immediately before (approaching phase) and during the obstacle crossing were analyzed in adaptive gait. Results indicated that AD patients walked more slowly during adaptive gait and free gait, using conservative strategies when confronted either with an obstacle or a secondary task. Furthermore, patients sought for stability to perform the tasks, particularly for adaptive gait with dual task, who used anticipatory and online adjustments to perform the task. Therefore, the increase of task complexity enhances cognitive load and risk of falls for AD patients.

  6. Adaptive Walking in Alzheimer's Disease

    PubMed Central

    Orcioli-Silva, Diego; Simieli, Lucas; Barbieri, Fabio Augusto; Stella, Florindo; Gobbi, Lilian Teresa Bucken

    2012-01-01

    The aim of this study is to analyze dual-task effects on free and adaptive gait in Alzheimer's disease (AD) patients. Nineteen elders with AD participated in the study. A veteran neuropsychiatrist established the degree of AD in the sample. To determine dual-task effects on free and adaptive gait, patients performed five trials for each experimental condition: free and adaptive gait with and without a dual-task (regressive countdown). Spatial and temporal parameters were collected through an optoelectronic tridimensional system. The central stride was analyzed in free gait, and the steps immediately before (approaching phase) and during the obstacle crossing were analyzed in adaptive gait. Results indicated that AD patients walked more slowly during adaptive gait and free gait, using conservative strategies when confronted either with an obstacle or a secondary task. Furthermore, patients sought for stability to perform the tasks, particularly for adaptive gait with dual task, who used anticipatory and online adjustments to perform the task. Therefore, the increase of task complexity enhances cognitive load and risk of falls for AD patients. PMID:22991684

  7. Microstructure of room temperature ionic liquids at stepped graphite electrodes

    DOE PAGES

    Feng, Guang; Li, Song; Zhao, Wei; ...

    2015-07-14

    Molecular dynamics simulations of room temperature ionic liquid (RTIL) [emim][TFSI] at stepped graphite electrodes were performed to investigate the influence of the thickness of the electrode surface step on the microstructure of interfacial RTILs. A strong correlation was observed between the interfacial RTIL structure and the step thickness in electrode surface as well as the ion size. Specifically, when the step thickness is commensurate with ion size, the interfacial layering of cation/anion is more evident; whereas, the layering tends to be less defined when the step thickness is close to the half of ion size. Furthermore, two-dimensional microstructure of ionmore » layers exhibits different patterns and alignments of counter-ion/co-ion lattice at neutral and charged electrodes. As the cation/anion layering could impose considerable effects on ion diffusion, the detailed information of interfacial RTILs at stepped graphite presented here would help to understand the molecular mechanism of RTIL-electrode interfaces in supercapacitors.« less

  8. Optimizing step gauge measurements and uncertainties estimation

    NASA Astrophysics Data System (ADS)

    Hennebelle, F.; Coorevits, T.; Vincent, R.

    2017-02-01

    According to the standard ISO 10360-2 (2001 Geometrical product specifications (GPS)—acceptance and reverification tests for coordinate measuring machines (CMM)—part 2: CMMs used for measuring size (ISO 10360-2:2001)), we verify the coordinate measuring machine (CMM) performance against the manufacturer specification. There are many types of gauges used for the calibration and verification of CMMs. The step gauges with parallel faces (KOBA, MITUTOYO) are well known gauges to perform this test. Often with these gauges, only the unidirectional measurements are considered which avoids having to deal with a residual error that affects the tip radius compensation. However the ISO 10360-2 standard imposes the use of a bidirectional measurement. Thus, the bidirectional measures must be corrected by the residual constant offset probe. In this paper, we optimize the step gauge measurement and a method is given to mathematically avoid the problem of the constant offset of the tip radius. This method involves measuring the step gauge once and to measure it a second time with a shift of one slot in order to obtain a new set of equations. Uncertainties are also presented.

  9. Universal Design: A Step toward Successful Aging

    PubMed Central

    Carr, Kelly; Weir, Patricia L.; Azar, Dory; Azar, Nadia R.

    2013-01-01

    The concept of aging successfully has become increasingly important as demographics shift towards an aging population. Successful aging has been defined to include (1) a low probability of disease and disease-related disability; (2) a high level of physical and cognitive functioning; and (3) an active engagement in life. The built environment can create opportunities or constraints for seniors to participate in social and productive activities. Universally designed spaces are more easily accessed and used by a spectrum of people without specialized adaptations. Thus, a universally designed environment creates opportunities for older adults to participate in these activities without the stigmatization associated with adapted or accessible designs. Providing older adults with specific universal design options (e.g., lever handle faucets) has the potential to increase the ease of completing activities of daily living, which promotes a continual engagement in life. Literature regarding universal design is promising; however, its theory requires further attention from professionals designing the built environment, evidence of the significance of its application from academics, and the embracement of its core principles from society. Overall, universal design has the potential to provide a stepping stone toward successful aging. PMID:23431446

  10. Comparing Anisotropic Output-Based Grid Adaptation Methods by Decomposition

    NASA Technical Reports Server (NTRS)

    Park, Michael A.; Loseille, Adrien; Krakos, Joshua A.; Michal, Todd

    2015-01-01

    Anisotropic grid adaptation is examined by decomposing the steps of flow solution, ad- joint solution, error estimation, metric construction, and simplex grid adaptation. Multiple implementations of each of these steps are evaluated by comparison to each other and expected analytic results when available. For example, grids are adapted to analytic metric fields and grid measures are computed to illustrate the properties of multiple independent implementations of grid adaptation mechanics. Different implementations of each step in the adaptation process can be evaluated in a system where the other components of the adaptive cycle are fixed. Detailed examination of these properties allows comparison of different methods to identify the current state of the art and where further development should be targeted.

  11. Small RNA Library Preparation Method for Next-Generation Sequencing Using Chemical Modifications to Prevent Adapter Dimer Formation

    PubMed Central

    Henderson, Jordana M.; Lebedev, Alexandre; Salcedo, Michelle P.; Zon, Gerald; McCaffrey, Anton P.; Paul, Natasha; Hogrefe, Richard I.

    2016-01-01

    For most sample types, the automation of RNA and DNA sample preparation workflows enables high throughput next-generation sequencing (NGS) library preparation. Greater adoption of small RNA (sRNA) sequencing has been hindered by high sample input requirements and inherent ligation side products formed during library preparation. These side products, known as adapter dimer, are very similar in size to the tagged library. Most sRNA library preparation strategies thus employ a gel purification step to isolate tagged library from adapter dimer contaminants. At very low sample inputs, adapter dimer side products dominate the reaction and limit the sensitivity of this technique. Here we address the need for improved specificity of sRNA library preparation workflows with a novel library preparation approach that uses modified adapters to suppress adapter dimer formation. This workflow allows for lower sample inputs and elimination of the gel purification step, which in turn allows for an automatable sRNA library preparation protocol. PMID:27875576

  12. A step-by-step methodology for enterprise interoperability projects

    NASA Astrophysics Data System (ADS)

    Chalmeta, Ricardo; Pazos, Verónica

    2015-05-01

    Enterprise interoperability is one of the key factors for enhancing enterprise competitiveness. Achieving enterprise interoperability is an extremely complex process which involves different technological, human and organisational elements. In this paper we present a framework to help enterprise interoperability. The framework has been developed taking into account the three domains of interoperability: Enterprise Modelling, Architecture and Platform and Ontologies. The main novelty of the framework in comparison to existing ones is that it includes a step-by-step methodology that explains how to carry out an enterprise interoperability project taking into account different interoperability views, like business, process, human resources, technology, knowledge and semantics.

  13. Writing a Simulation Scenario: A Step-By-Step Guide.

    PubMed

    Bambini, Deborah

    2016-02-01

    Simulation is becoming a widely used method of helping nurses learn and maintain competency in the clinical area for both staff educators in clinical settings and nursing faculty in academic settings. Designing an effective simulation experience requires thoughtful planning, knowledge of educational principles, and knowledge of best practices in both simulation and clinical practice. An evidence-based strategy for writing a simulation scenario for nurses and other health care providers in any setting is described. A step-by-step process is outlined that incorporates best practices. Examples and suggestions are provided to help readers create quality simulation experiences.

  14. Partial Return Yoke for MICE Step IV and Final Step

    SciTech Connect

    Witte, Holger; Plate, Stephen; Berg, J.Scott; Tarrant, Jason; Bross, Alan

    2015-06-01

    This paper reports on the progress of the design and construction of a retro-fitted return yoke for the international Muon Ionization Cooling Experiment (MICE). MICE is a proof-of-principle experiment aiming to demonstrate ionization cooling experimentally. In earlier studies we outlined how a partial return yoke can be used to mitigate stray magnetic field in the experimental hall; we report on the progress of the construction of the partial return yoke for MICE Step IV. We also discuss an extension of the Partial Return Yoke for the final step of MICE; we show simulation results of the expected performance.

  15. Adaptive clinical trial designs in oncology

    PubMed Central

    Zang, Yong; Lee, J. Jack

    2015-01-01

    Adaptive designs have become popular in clinical trial and drug development. Unlike traditional trial designs, adaptive designs use accumulating data to modify the ongoing trial without undermining the integrity and validity of the trial. As a result, adaptive designs provide a flexible and effective way to conduct clinical trials. The designs have potential advantages of improving the study power, reducing sample size and total cost, treating more patients with more effective treatments, identifying efficacious drugs for specific subgroups of patients based on their biomarker profiles, and shortening the time for drug development. In this article, we review adaptive designs commonly used in clinical trials and investigate several aspects of the designs, including the dose-finding scheme, interim analysis, adaptive randomization, biomarker-guided randomization, and seamless designs. For illustration, we provide examples of real trials conducted with adaptive designs. We also discuss practical issues from the perspective of using adaptive designs in oncology trials. PMID:25811018

  16. Step by Step: Using Kodaly To Build Vocal Improvisation.

    ERIC Educational Resources Information Center

    Whitcomb, Rachel

    2003-01-01

    Describes how to teach elementary students about vocal improvisation using the Kodaly-based approach. Discusses the three steps involved in this technique: (1) develop familiar singing patterns; (2) use a question and answer format; and (3) begin improvisation. Includes examples of solfege patterns and a vocal question and answer. (CMK)

  17. Finite element simulation of adaptive aerospace structures with SMA actuators

    NASA Astrophysics Data System (ADS)

    Frautschi, Jason; Seelecke, Stefan

    2003-07-01

    The particular demands of aerospace engineering have spawned many of the developments in the field of adaptive structures. Shape memory alloys are particularly attractive as actuators in these types of structures due to their large strains, high specific work output and potential for structural integration. However, the requisite extensive physical testing has slowed development of potential applications and highlighted the need for a simulation tool for feasibility studies. In this paper we present an implementation of an extended version of the M'ller-Achenbach SMA model into a commercial finite element code suitable for such studies. Interaction between the SMA model and the solution algorithm for the global FE equations is thoroughly investigated with respect to the effect of tolerances and time step size on convergence, computational cost and accuracy. Finally, a simulation of a SMA-actuated flexible trailing edge of an aircraft wing modeled with beam elements is presented.

  18. Adaptive evolutionary artificial neural networks for pattern classification.

    PubMed

    Oong, Tatt Hee; Isa, Nor Ashidi Mat

    2011-11-01

    This paper presents a new evolutionary approach called the hybrid evolutionary artificial neural network (HEANN) for simultaneously evolving an artificial neural networks (ANNs) topology and weights. Evolutionary algorithms (EAs) with strong global search capabilities are likely to provide the most promising region. However, they are less efficient in fine-tuning the search space locally. HEANN emphasizes the balancing of the global search and local search for the evolutionary process by adapting the mutation probability and the step size of the weight perturbation. This is distinguishable from most previous studies that incorporate EA to search for network topology and gradient learning for weight updating. Four benchmark functions were used to test the evolutionary framework of HEANN. In addition, HEANN was tested on seven classification benchmark problems from the UCI machine learning repository. Experimental results show the superior performance of HEANN in fine-tuning the network complexity within a small number of generations while preserving the generalization capability compared with other algorithms.

  19. Step-by-step phacoemulsification training program for ophthalmology residents

    PubMed Central

    Yulan, Wang; Yaohua, Sheng; Jinhua, Tao; Min, Wang

    2013-01-01

    Aims: The aim was to analyze the learning curve of phacoemulsification (phaco) performed by residents without experience in performing extra-capsular cataract extraction (ECCE) in a step-by-step training program (SBSTP). Materials and Methods: Consecutive surgical records of phaco performed from March 2009 to Sept 2011 by four residents without previous ECCE experience were retrospectively reviewed. The completion rate of the first 30 procedures by each resident was calculated. The main intraoperative phaco parameter records for the first 30 surgeries by each resident were compared with those for their last 30 surgeries. Intraoperative complications in the residents’ procedures were also recorded and analyzed. Results: A total of 1013 surgeries were performed by residents. The completion rate for the first 30 phaco procedures was 79.2 ± 5.8%. The main reasons for halting the procedure were as follows: Anterior capsule tear, inability to crack the nucleus, and posterior capsular rupture during phaco or cortex removal. Cumulative dissipated energy of phaco power used during the surgeries was significantly less in the last 30 cases compared with the first 30 cases (30.10 ± 17.58 vs. 55.41 ± 37.59, P = 0.021). Posterior capsular rupture rate was 2.5 ± 1.2% in total (10.8 ± 4.2% in the first 30 cases and 1.7 ± 1.9% in the last 30 cases, P = 0.008; a statistically significant difference). Conclusion: The step-by-step training program might be a necessary process for a resident to transit from dependence to a self-supported operator. It is also an essential middle step between wet lab training to performing the entire phaco procedure on the patient both effectively and safely. PMID:24178407

  20. Step-by-step magic state encoding for efficient fault-tolerant quantum computation.

    PubMed

    Goto, Hayato

    2014-12-16

    Quantum error correction allows one to make quantum computers fault-tolerant against unavoidable errors due to decoherence and imperfect physical gate operations. However, the fault-tolerant quantum computation requires impractically large computational resources for useful applications. This is a current major obstacle to the realization of a quantum computer. In particular, magic state distillation, which is a standard approach to universality, consumes the most resources in fault-tolerant quantum computation. For the resource problem, here we propose step-by-step magic state encoding for concatenated quantum codes, where magic states are encoded step by step from the physical level to the logical one. To manage errors during the encoding, we carefully use error detection. Since the sizes of intermediate codes are small, it is expected that the resource overheads will become lower than previous approaches based on the distillation at the logical level. Our simulation results suggest that the resource requirements for a logical magic state will become comparable to those for a single logical controlled-NOT gate. Thus, the present method opens a new possibility for efficient fault-tolerant quantum computation.

  1. Steps of Reprocessing and Equipments

    PubMed Central

    Lee, Yong Kook

    2013-01-01

    With the increasing interest in endoscopy and the rising number of endoscopic examinations in hospitals, the importance of endoscopic reprocessing is also increasing. Cure facilities that are understaffed and ill-equipped are trying to cope with the problems of insufficient cleaning and high infection risks. To prevent endoscopy-associated infection, the endoscope cleaning, and disinfection guidelines prepared by the Korean Society of Gastrointestinal Endoscopy must be followed. In this review, the steps of endoscopic reprocessing and the equipments required in each step are discussed. PMID:23767039

  2. Job Interviews: 10 Steps to Success! Pocket Job Series No. 4.

    ERIC Educational Resources Information Center

    Lindgren, Amy

    This book is the fourth in a series of six pocket-sized books written for career changers and laid-off workers. Each book is written at a 7th- to 10th-grade reading level and contains examples, hands-on self-discovery exercises, and step-by-step advice for a successful job search. This book provides a step-by-step process for succeeding in any…

  3. Changing Careers: Steps to Success.

    ERIC Educational Resources Information Center

    Sikula, Lola

    This book is intended to assist adults who are contemplating changing careers or actually doing so. The information, exercises, questionnaires, guides, and bibliographies included in it are designed to give adults the coping skills to adapt to and work through the personal, financial, and other changes that accompany the career change process. The…

  4. Efficacy of a step-by-step carving technique for dental students.

    PubMed

    Kilistoff, Alan J; Mackenzie, Louis; D'Eon, Marcel; Trinder, Krista

    2013-01-01

    This study demonstrates the effectiveness of a step-by-step carving technique that is quickly and efficiently mastered by dental students. Thirty-six final-year dental students volunteered to participate in this study. The students were given pre-prepared lower right first molar simulation teeth that had the occlusal half replaced in carving wax. The study was conducted in three time phases: pre-test (Time 1), participative learning (Time 2), and post-test (Time 3). The pre-test had the students carve the wax with no instruction. Instruction and demonstration of the technique were given at Time 2, and the post-test had the students carve the tooth again with no guidance but with training. A statistically significant increase with a nearly medium effect size was found from Time 1 to Time 2. A statistically significant increase with a medium effect size was found when comparing Time 2 to Time 3. A statistically significant increase with a large effect size was found when comparing Time 1 to Time 3. This technique has proved to be an effective method of simultaneously teaching a large cohort of predoctoral dental students. The technique is consistent with constructivist learning theory.

  5. Simple adaptive cubic spline interpolation of fluorescence decay functions

    NASA Astrophysics Data System (ADS)

    Kuśba, J.; Czuper, A.

    2007-05-01

    Simple method allowing for adaptive cubic spline interpolation of fluorescence decay functions is proposed. In the first step of the method, the interpolated function is integrated using the known adaptive algorithm based on Newton-Cotes quadratures. It is shown that, in this step, application of the Simpson's rule provides the smallest number of calls of the interpolated function. In the second step of the method, a typical cubic spline approximation is used to find values of the interpolated function between the points evaluated in the first step.

  6. Motion mode recognition and step detection algorithms for mobile phone users.

    PubMed

    Susi, Melania; Renaudin, Valérie; Lachapelle, Gérard

    2013-01-24

    Microelectromechanical Systems (MEMS) technology is playing a key role in the design of the new generation of smartphones. Thanks to their reduced size, reduced power consumption, MEMS sensors can be embedded in above mobile devices for increasing their functionalities. However, MEMS cannot allow accurate autonomous location without external updates, e.g., from GPS signals, since their signals are degraded by various errors. When these sensors are fixed on the user's foot, the stance phases of the foot can easily be determined and periodic Zero velocity UPdaTes (ZUPTs) are performed to bound the position error. When the sensor is in the hand, the situation becomes much more complex. First of all, the hand motion can be decoupled from the general motion of the user. Second, the characteristics of the inertial signals can differ depending on the carrying modes. Therefore, algorithms for characterizing the gait cycle of a pedestrian using a handheld device have been developed. A classifier able to detect motion modes typical for mobile phone users has been designed and implemented. According to the detected motion mode, adaptive step detection algorithms are applied. Success of the step detection process is found to be higher than 97% in all motion modes.

  7. Motion Mode Recognition and Step Detection Algorithms for Mobile Phone Users

    PubMed Central

    Susi, Melania; Renaudin, Valérie; Lachapelle, Gérard

    2013-01-01

    Microelectromechanical Systems (MEMS) technology is playing a key role in the design of the new generation of smartphones. Thanks to their reduced size, reduced power consumption, MEMS sensors can be embedded in above mobile devices for increasing their functionalities. However, MEMS cannot allow accurate autonomous location without external updates, e.g., from GPS signals, since their signals are degraded by various errors. When these sensors are fixed on the user's foot, the stance phases of the foot can easily be determined and periodic Zero velocity UPdaTes (ZUPTs) are performed to bound the position error. When the sensor is in the hand, the situation becomes much more complex. First of all, the hand motion can be decoupled from the general motion of the user. Second, the characteristics of the inertial signals can differ depending on the carrying modes. Therefore, algorithms for characterizing the gait cycle of a pedestrian using a handheld device have been developed. A classifier able to detect motion modes typical for mobile phone users has been designed and implemented. According to the detected motion mode, adaptive step detection algorithms are applied. Success of the step detection process is found to be higher than 97% in all motion modes. PMID:23348038

  8. Seven Steps to Successful Inclusion.

    ERIC Educational Resources Information Center

    Whitworth, Jerry

    This report highlights the experiences of the Lighthouse Project, which successfully included students with disabilities in elementary, middle, and high school general education classes in a school district in southwest Tennessee. Drawing on findings from the Lighthouse Project, the report describes the following seven steps that must be present…

  9. Ten Steps to "TQM Plus."

    ERIC Educational Resources Information Center

    Kaufman, Roger; Hirumi, Atsusi

    1992-01-01

    Total Quality Management Plus (TQM) goes beyond customer satisfaction to consider quality of life, environmental conditions, crime rates, and health and well-being. Steps to integrate such concerns into the TQM process include being ready for challenges, creating a quality system to collect performance data, defining the ideal school and world…

  10. Design of converging stepped spillways

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Roller compacted concrete (RCC) stepped spillways are growing in popularity for providing overtopping protection for aging watershed dams with inadequate auxiliary spillway capacity and for the construction of new dams. Unobtainable land rights, topographic features, and land use changes caused by ...

  11. Evaluation of Florida's STEP Program.

    ERIC Educational Resources Information Center

    Florida State Dept. of Health and Rehabilitative Services, Tallahassee.

    Project STEP (Short Term Elective Program) is an outdoor-educational program that, through teaching wilderness survival skills and affording a necessity for their use, provides juvenile delinquents with a feeling of self-reliance and self-worth. The program is designed for committed youths, primarily males, at least 13 to 14 years of age, but…

  12. Ten Steps for Peace Education

    ERIC Educational Resources Information Center

    n/a

    2005-01-01

    This brief guide is for parents and teachers who seek to nurture the values of compassion and good will in their children?s lives. It describes ten steps or actions to promote peace and goodwill in the home, in family activities, and in school.

  13. One-Step Coal Liquefaction

    NASA Technical Reports Server (NTRS)

    Qader, S. A.

    1984-01-01

    Steam injection improves yield and quality of product. Single step process for liquefying coal increases liquid yield and reduces hydrogen consumption. Principal difference between this and earlier processes includes injection of steam into reactor. Steam lowers viscosity of liquid product, so further upgrading unnecessary.

  14. Two step continuous method to synthesize colloidal spheroid gold nanorods.

    PubMed

    Chandra, S; Doran, J; McCormack, S J

    2015-12-01

    This research investigated a two-step continuous process to synthesize colloidal suspension of spheroid gold nanorods. In the first step; gold precursor was reduced to seed-like particles in the presence of polyvinylpyrrolidone and ascorbic acid. In continuous second step; silver nitrate and alkaline sodium hydroxide produced various shape and size Au nanoparticles. The shape was manipulated through weight ratio of ascorbic acid to silver nitrate by varying silver nitrate concentration. The specific weight ratio of 1.35-1.75 grew spheroid gold nanorods of aspect ratio ∼1.85 to ∼2.2. Lower weight ratio of 0.5-1.1 formed spherical nanoparticle. The alkaline medium increased the yield of gold nanorods and reduced reaction time at room temperature. The synthesized gold nanorods retained their shape and size in ethanol. The surface plasmon resonance was red shifted by ∼5 nm due to higher refractive index of ethanol than water.

  15. Cytoplasmic Volume Modulates Spindle Size During Embryogenesis

    PubMed Central

    Good, Matthew C.; Vahey, Michael D.; Skandarajah, Arunan; Fletcher, Daniel A.; Heald, Rebecca

    2014-01-01

    Rapid and reductive cell divisions during embryogenesis require that intracellular structures adapt to a wide range of cell sizes. The mitotic spindle presents a central example of this flexibility, scaling with the dimensions of the cell to mediate accurate chromosome segregation. To determine whether spindle size regulation is achieved through a developmental program or is intrinsically specified by cell size or shape, we developed a system to encapsulate cytoplasm from Xenopus eggs and embryos inside cell-like compartments of defined sizes. Spindle size was observed to shrink with decreasing compartment size, similar to what occurs during early embryogenesis, and this scaling trend depended on compartment volume rather than shape. Thus, the amount of cytoplasmic material provides a mechanism for regulating the size of intracellular structures. PMID:24233724

  16. Dissecting a complex neurosurgical illustration: step-by-step development.

    PubMed

    Suk, Ian

    2011-12-01

    Modern computer graphics software has enabled the medical illustrator to render very complex anatomy by composing many different layers of drawings simultaneously. This and the author's capacity to take an "editorial" approach to compress several chronological events into a single, comprehensive two-dimensional illustration are analyzed in a step-by-step process. Through a series of images, the article provides a visual synopsis of the development of an illustration for an extensive clinical case: total sacrectomy performed through an all-posterior approach. Originally given as a slide presentation at the American Association of Neurological Surgeons Theodore Kurze Lecture in April 2011, the article provides some detailed notes on the techniques the author used to develop a comprehensive neurosurgical illustration.

  17. Saccadic Adaptation in 10–41 Month-Old Children

    PubMed Central

    Lemoine-Lardennois, Christelle; Alahyane, Nadia; Tailhefer, Coline; Collins, Thérèse; Fagard, Jacqueline; Doré-Mazars, Karine

    2016-01-01

    When saccade amplitude becomes systematically inaccurate, adaptation mechanisms gradually decrease or increase it until accurate saccade targeting is recovered. Adaptive shortening and adaptive lengthening of saccade amplitude rely on separate mechanisms in adults. When these adaptation mechanisms emerge during development is poorly known except that adaptive shortening processes are functional in children above 8 years of age. Yet, saccades in infants are consistently inaccurate (hypometric) as if adaptation mechanisms were not fully functional in early childhood. Here, we tested reactive saccade adaptation in 10–41 month-old children compared to a group of 20–30 year-old adults. A visual target representing a cartoon character appeared at successive and unpredictable locations 10° apart on a computer screen. During the eye movement toward the target, it systematically stepped in the direction opposite to the saccade to induce an adaptive shortening of saccade amplitude (Experiment 1). In Experiment 2, the target stepped in the same direction as the ongoing saccade to induce an adaptive lengthening of saccade amplitude. In both backward and forward adaptation experiments, saccade adaptation was compared to a control condition where there was no intrasaccadic target step. Analysis of baseline performance revealed both longer saccade reaction times and hypometric saccades in children compared to adults. In both experiments, children on average showed gradual changes in saccade amplitude consistent with the systematic intrasaccadic target steps. Moreover, the amount of amplitude change was similar between children and adults for both backward and forward adaptation. Finally, adaptation abilities in our child group were not related to age. Overall the results suggest that the neural mechanisms underlying reactive saccade adaptation are in place early during development. PMID:27252640

  18. One size fits all: Eurasian lynx females share a common optimal litter size.

    PubMed

    Gaillard, Jean-Michel; Nilsen, Erlend B; Odden, John; Andrén, Henrik; Linnell, John D C

    2014-01-01

    Lack proposed that the average clutch size of altricial species should be determined by the average maximum number of young the parents can raise such that all females in a given population should share a common optimal clutch size. Support for this model remains equivocal and recent studies have suggested that intra-population variation in clutch size is adaptive because each female has its own optimal clutch size associated with its intrinsic ability to raise offspring. Although Lack litter size and condition-dependent litter size are presented as two competing models, both are based on the concept of individual optimization. We propose a unified optimal litter size model (called 'adaptive litter size') and identify a set of conditions under which a common vs. a state-dependent optimal litter size should be observed. We test whether females of Eurasian lynx (Lynx lynx) have a common optimal litter size, or whether they adjust their litter size according to their state. We used a detailed individual-based data set collected from contrasting populations of Eurasian lynx in Scandinavia. Observed reproductive patterns in female lynx provide strong support for the existence of a common optimal litter size. Litter size did not vary according to female body mass or reproductive category, or among contrasted populations and years. A litter size of 2 was associated with a higher fitness than both smaller and larger litters, and thus corresponded to the 'adaptive litter size' for female lynx. We suggest that the reproductive pattern of female lynx might correspond to a risk avoidance tactic common to all individuals, which has evolved in response to strong environmental constraints generated by a highly unpredictable food supply during lactation.

  19. [The central vein catheterization. 2. Procedure, step by step].

    PubMed

    Schmalz-Ott, Stéphane; Monti, Matteo; Vollenweider, Peter

    2008-10-29

    Several approaches exist for central vein catheterization. Mastery of the various steps of this procedure and understanding of the basics of asepsis are critical to prevent any complication. They also built the basis for an exhaustive communication with the patient, to obtain an informed consent. This article can in addition be used to develop a checklist in order to (self-)assess competence in procedural skills.

  20. Undertaking a literature review: a step-by-step approach.

    PubMed

    Cronin, Patricia; Ryan, Frances; Coughlan, Michael

    Nowadays, most nurses, pre- and post-qualification, will be required to undertake a literature review at some point, either as part of a course of study, as a key step in the research process, or as part of clinical practice development or policy. For student nurses and novice researchers it is often seen as a difficult undertaking. It demands a complex range of skills, such as learning how to define topics for exploration, acquiring skills of literature searching and retrieval, developing the ability to analyse and synthesize data as well as becoming adept at writing and reporting, often within a limited time scale. The purpose of this article is to present a step-by-step guide to facilitate understanding by presenting the critical elements of the literature review process. While reference is made to different types of literature reviews, the focus is on the traditional or narrative review that is undertaken, usually either as an academic assignment or part of the research process.

  1. Power laws, discontinuities and regional city size distributions

    USGS Publications Warehouse

    Garmestani, A.S.; Allen, C.R.; Gallagher, C.M.

    2008-01-01

    Urban systems are manifestations of human adaptation to the natural environment. City size distributions are the expression of hierarchical processes acting upon urban systems. In this paper, we test the entire city size distributions for the southeastern and southwestern United States (1990), as well as the size classes in these regions for power law behavior. We interpret the differences in the size of the regional city size distributions as the manifestation of variable growth dynamics dependent upon city size. Size classes in the city size distributions are snapshots of stable states within urban systems in flux. ?? 2008.

  2. Stilt walking: how do we learn those first steps?

    PubMed

    Akram, Sakineh B; Frank, James S

    2009-09-01

    This study examined how young healthy adults learn stilt walking. Ten healthy male university students attended two sessions of testing held on two consecutive days. In each session participants performed three blocks of 10 stilt-walking trials. Angular movements of head and trunk and the spatial and temporal gait parameters were recorded. When walking on stilts young adults improved their gait velocity through modifications of step parameters while maintaining trunk movements close to that observed during normal over-ground walking. Participants improved their performance by increasing their step frequency and step length and reducing the double support percentage of the gait cycle. Stilts are often used for drywall installation, painting over-the-head areas and raising workers above the ground without the burden of erecting scaffolding. This research examines the locomotor adaptation as young healthy adults learn the complex motor task of stilt walking; a task that is frequently used in the construction industry.

  3. Industrial-size photobioreactors

    SciTech Connect

    Ogbonna, J.C.; Tanaka, Hideo

    1997-07-01

    Photosynthetic microorganisms can be engineered to produce pharmaceuticals, chemical intermediates, and clean energy (e.g., hydrogen). They also fix atmospheric carbon dioxide--an important consideration as increased levels of carbon dioxide are linked to global warming. As a first step in the photobioreactor design, the authors investigated the relative significance of the exponential and the linear growth rates during light-limited batch cultivation of photosynthetic cells using various types and sizes of photobioreactors. They also developed a mathematical model that could explain the existence of the various growth phases during the light-limited batch cultivation. Because the cost of electricity is high, use of solar energy is obviously desirable, because it is abundant and free. However, an appropriate method for harvesting the solar energy and distributing the light inside the photobioreactor is required. A light collection device consisting of Fresnel lenses is used to collect the solar light, which is then distributed inside the reactor through the optical fibers. Because the position of the sun changes continuously, the device is equipped with a light-tracking sensor so that the lenses rotate with the position of the sun. Because of diurnal and seasonal changes in the sunlight intensity, however, high volumetric productivity is difficult to achieve if only solar energy is used for reactor illumination. For maximum productivity, therefore, the solar light should be supplemented with an artificial light source at night and on cloudy days.

  4. Step tracking program for concentrator solar collectors

    NASA Astrophysics Data System (ADS)

    Ciobanu, D.; Jaliu, C.

    2016-08-01

    The increasing living standards in developed countries lead to increased energy consumption. The fossil fuel consumption and greenhouse gas effect that accompany the energy production can be reduced by using renewable energy. For instance, the solar thermal systems can be used in temperate climates to provide heating during the transient period or cooling during the warmer months. Most used solar thermal systems contain flat plate solar collectors. In order to provide the necessary energy for the house cooling system, the cooling machine uses a working fluid with a high temperature, which can be supplied by dish concentrator collectors. These collectors are continuously rotated towards sun by biaxial tracking systems, process that increases the consumed power. An algorithm for a step tracking program to be used in the orientation of parabolic dish concentrator collectors is proposed in the paper to reduce the consumed power due to actuation. The algorithm is exemplified on a case study: a dish concentrator collector to be implemented in Brasov, Romania, a location with the turbidity factor TR equal to 3. The size of the system is imposed by the environment, the diameter of the dish reflector being of 3 meters. By applying the proposed algorithm, 60 sub-programs are obtained for the step orientation of the parabolic dish collector over the year. Based on the results of the numerical simulations for the step orientation, the efficiency of the direct solar radiation capture on the receptor is up to 99%, while the energy consumption is reduced by almost 80% compared to the continuous actuation of the concentrator solar collector.

  5. Climate change adaptation for the US National Wildlife Refuge System

    USGS Publications Warehouse

    Griffith, Brad; Scott, J. Michael; Adamcik, Robert S.; Ashe, Daniel; Czech, Brian; Fischman, Robert; Gonzalez, Patrick; Lawler, Joshua J.; McGuire, A. David; Pidgorna, Anna

    2009-01-01

    Since its establishment in 1903, the National Wildlife Refuge System (NWRS) has grown to 635 units and 37 Wetland Management Districts in the United States and its territories. These units provide the seasonal habitats necessary for migratory waterfowl and other species to complete their annual life cycles. Habitat conversion and fragmentation, invasive species, pollution, and competition for water have stressed refuges for decades, but the interaction of climate change with these stressors presents the most recent, pervasive, and complex conservation challenge to the NWRS. Geographic isolation and small unit size compound the challenges of climate change, but a combined emphasis on species that refuges were established to conserve and on maintaining biological integrity, diversity, and environmental health provides the NWRS with substantial latitude to respond. Individual symptoms of climate change can be addressed at the refuge level, but the strategic response requires system-wide planning. A dynamic vision of the NWRS in a changing climate, an explicit national strategic plan to implement that vision, and an assessment of representation, redundancy, size, and total number of units in relation to conservation targets are the first steps toward adaptation. This adaptation must begin immediately and be built on more closely integrated research and management. Rigorous projections of possible futures are required to facilitate adaptation to change. Furthermore, the effective conservation footprint of the NWRS must be increased through land acquisition, creative partnerships, and educational programs in order for the NWRS to meet its legal mandate to maintain the biological integrity, diversity, and environmental health of the system and the species and ecosystems that it supports.

  6. Climate change adaptation for the US National Wildlife Refuge System.

    PubMed

    Griffith, Brad; Scott, J Michael; Adamcik, Robert; Ashe, Daniel; Czech, Brian; Fischman, Robert; Gonzalez, Patrick; Lawler, Joshua; McGuire, A David; Pidgorna, Anna

    2009-12-01

    Since its establishment in 1903, the National Wildlife Refuge System (NWRS) has grown to 635 units and 37 Wetland Management Districts in the United States and its territories. These units provide the seasonal habitats necessary for migratory waterfowl and other species to complete their annual life cycles. Habitat conversion and fragmentation, invasive species, pollution, and competition for water have stressed refuges for decades, but the interaction of climate change with these stressors presents the most recent, pervasive, and complex conservation challenge to the NWRS. Geographic isolation and small unit size compound the challenges of climate change, but a combined emphasis on species that refuges were established to conserve and on maintaining biological integrity, diversity, and environmental health provides the NWRS with substantial latitude to respond. Individual symptoms of climate change can be addressed at the refuge level, but the strategic response requires system-wide planning. A dynamic vision of the NWRS in a changing climate, an explicit national strategic plan to implement that vision, and an assessment of representation, redundancy, size, and total number of units in relation to conservation targets are the first steps toward adaptation. This adaptation must begin immediately and be built on more closely integrated research and management. Rigorous projections of possible futures are required to facilitate adaptation to change. Furthermore, the effective conservation footprint of the NWRS must be increased through land acquisition, creative partnerships, and educational programs in order for the NWRS to meet its legal mandate to maintain the biological integrity, diversity, and environmental health of the system and the species and ecosystems that it supports.

  7. Maternal Size and Age Shape Offspring Size in a Live-Bearing Fish, Xiphophorus birchmanni

    PubMed Central

    Kindsvater, Holly K.; Rosenthal, Gil G.; Alonzo, Suzanne H.

    2012-01-01

    Many studies of offspring size focus on differences in maternal investment that arise from ecological factors such as predation or competition. Classic theory predicts that these ecological factors will select for an optimal offspring size, and therefore that variation in a given environment will be minimized. Yet recent evidence suggests maternal traits such as size or age could also drive meaningful variation in offspring size. The generality of this pattern is unclear, as some studies suggest that it may represent non-adaptive variation or be an artifact of temporal or spatial differences in maternal environments. To clarify this pattern, we asked how maternal size, age and condition are related to each other in several populations of the swordtail Xiphophorus birchmanni. We then determined how these traits are related to offspring size, and whether they could resolve unexplained intra-population variation in this trait. We found that female size, age, and condition are correlated within populations; at some of these sites, older, larger females produce larger offspring than do younger females. The pattern was robust to differences among most, but not all, sites. Our results document a pattern that is consistent with recent theory predicting adaptive age- and size-dependence in maternal investment. Further work is needed to rule out non-adaptive explanations for this variation. Our results suggest that female size and age could play an under-appreciated role in population growth and evolution. PMID:23139785

  8. Adaptive sampling for noisy problems

    SciTech Connect

    Cantu-Paz, E

    2004-03-26

    The usual approach to deal with noise present in many real-world optimization problems is to take an arbitrary number of samples of the objective function and use the sample average as an estimate of the true objective value. The number of samples is typically chosen arbitrarily and remains constant for the entire optimization process. This paper studies an adaptive sampling technique that varies the number of samples based on the uncertainty of deciding between two individuals. Experiments demonstrate the effect of adaptive sampling on the final solution quality reached by a genetic algorithm and the computational cost required to find the solution. The results suggest that the adaptive technique can effectively eliminate the need to set the sample size a priori, but in many cases it requires high computational costs.

  9. Meissner-Effect Stepping Motor

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    1991-01-01

    Proposed stepping motor derives torque from diamagnetic repulsion produced by Meissner effect - exclusion of magnetic field from interior of superconductor. Design of motor takes advantage of silver-doped YB2Cu3O and other compounds superconductive at temperatures as high as that of liquid nitrogen. Skin of rotor cooled below its superconducting-transition temperature by liquid nitrogen. O-rings prevent leaks of liquid nitrogen from rotor. Weight, cost, and maintenance reduced.

  10. Adaptation to climate change in developing countries.

    PubMed

    Mertz, Ole; Halsnaes, Kirsten; Olesen, Jørgen E; Rasmussen, Kjeld

    2009-05-01

    Adaptation to climate change is given increasing international attention as the confidence in climate change projections is getting higher. Developing countries have specific needs for adaptation due to high vulnerabilities, and they will in this way carry a great part of the global costs of climate change although the rising atmospheric greenhouse gas concentrations are mainly the responsibility of industrialized countries. This article provides a status of climate change adaptation in developing countries. An overview of observed and projected climate change is given, and recent literature on impacts, vulnerability, and adaptation are reviewed, including the emerging focus on mainstreaming of climate change and adaptation in development plans and programs. The article also serves as an introduction to the seven research articles of this special issue on climate change adaptation in developing countries. It is concluded that although many useful steps have been taken in the direction of ensuring adequate adaptation in developing countries, much work still remains to fully understand the drivers of past adaptation efforts, the need for future adaptation, and how to mainstream climate into general development policies.

  11. Adaptive Highlighting of Links to Assist Surfing on the Internet

    DTIC Science & Technology

    2002-01-01

    in about 5 to 10 steps, or less. Keywords: Internet, search, intelligent crawler, reinforcement learning , adaptivity, information filtering 1...into the value estimation algorithm to be described below. 2.5 Adaptation 2.5.1 On-line reinforcement learning (RL) RL is the state-of-the-art method...window update, dotted line: reinforcement learning . User switched weights randomly in every 50 steps. In the moving window update experiment the

  12. Size and scaling in human evolution.

    PubMed

    Pilbeam, D; Gould, S J

    1974-12-06

    Our general conclusion is simply stated: many lineages display phyletic size increase; allometric changes almost always accompany increase in body size. We cannot judge adaptation until we separate such changes into those required by increasing size and those serving as special adaptations to changing environments. In our view, the three australopithecines are, in a number of features, scaled variants of the "same" animal. In these characters, A. africanus is no more "advanced" than the larger, more robust forms. The one early hominid to show a significant departure from this adaptive pattern toward later hominids-cranially, dentally, and postcranially-is H. habilis from East Africa. The australopithecines, one of which was probably a precursor of the Homolineage, were apparently a successful group of basically vegetarian hominids, more advanced behaviorally than apes (87), but not hunter-gatherers. The fossil hominids of Africa fall into two major groupings. One probable lineage, the australopithecines, apparently became extinct without issue; the other evolved to modern man. Both groups displayed steady increase in body size. We consider quantitatively two key characters of the hominid skull: cranial capacity and cheek tooth size. The variables are allometrically related to body size in both lineages. In australopithecines, the manner of relative growth neatly meets the predictions for functional equivalence over a wide range of sizes (negative allometry of cranial capacity with a slope against body weight of 0.2 to 0.4 and positive allometry of postcanine area with a slope near 0.75). In the A. africanus to H. sapiens lineage, cranial capacity increases with positive allometry (slope 1.73) while cheek teeth decrease absolutely (slope - 0.725). Clearly, these are special adaptations unrelated to the physical requirements of increasing body size. We examined qualitatively other features, which also seem to vary allometrically. Of course, many characters should be

  13. Adaptive Changes in Grain-Size in Morphological Processing

    ERIC Educational Resources Information Center

    Lee, Chang H.

    2008-01-01

    Substantial neurobiological data indicate that the dominant cortical region for printed-word recognition shifts from a temporo-parietal (dorsal) to an occipito-temporal (ventral) locus with increasing recognition experience. The circuits also have different characteristic speeds of response and word preferences. Previous evidence suggested that…

  14. Sample Size Reassessment and Hypothesis Testing in Adaptive Survival Trials

    PubMed Central

    Magirr, Dominic; Jaki, Thomas; Koenig, Franz; Posch, Martin

    2016-01-01

    Mid-study design modifications are becoming increasingly accepted in confirmatory clinical trials, so long as appropriate methods are applied such that error rates are controlled. It is therefore unfortunate that the important case of time-to-event endpoints is not easily handled by the standard theory. We analyze current methods that allow design modifications to be based on the full interim data, i.e., not only the observed event times but also secondary endpoint and safety data from patients who are yet to have an event. We show that the final test statistic may ignore a substantial subset of the observed event times. An alternative test incorporating all event times is found, where a conservative assumption must be made in order to guarantee type I error control. We examine the power of this approach using the example of a clinical trial comparing two cancer therapies. PMID:26863139

  15. A multi-step transversal linearization (MTL) method in non-linear structural dynamics

    NASA Astrophysics Data System (ADS)

    Roy, D.; Kumar, Rajesh

    2005-10-01

    interpolation increases, the Lagrangian interpolation is shown to overcome this numerical problem. Finally, the family of MTL methods is illustrated through limited numerical results for a couple of harmonically driven workhorse oscillators, viz. the hardening Duffing and the Duffing-Holmes' oscillators. Comparisons with results obtained via a sixth-order Runge-Kutta method with adaptive time step-sizes are also provided.

  16. Adaptive Image Denoising by Mixture Adaptation

    NASA Astrophysics Data System (ADS)

    Luo, Enming; Chan, Stanley H.; Nguyen, Truong Q.

    2016-10-01

    We propose an adaptive learning procedure to learn patch-based image priors for image denoising. The new algorithm, called the Expectation-Maximization (EM) adaptation, takes a generic prior learned from a generic external database and adapts it to the noisy image to generate a specific prior. Different from existing methods that combine internal and external statistics in ad-hoc ways, the proposed algorithm is rigorously derived from a Bayesian hyper-prior perspective. There are two contributions of this paper: First, we provide full derivation of the EM adaptation algorithm and demonstrate methods to improve the computational complexity. Second, in the absence of the latent clean image, we show how EM adaptation can be modified based on pre-filtering. Experimental results show that the proposed adaptation algorithm yields consistently better denoising results than the one without adaptation and is superior to several state-of-the-art algorithms.

  17. Adaptive Image Denoising by Mixture Adaptation.

    PubMed

    Luo, Enming; Chan, Stanley H; Nguyen, Truong Q

    2016-10-01

    We propose an adaptive learning procedure to learn patch-based image priors for image denoising. The new algorithm, called the expectation-maximization (EM) adaptation, takes a generic prior learned from a generic external database and adapts it to the noisy image to generate a specific prior. Different from existing methods that combine internal and external statistics in ad hoc ways, the proposed algorithm is rigorously derived from a Bayesian hyper-prior perspective. There are two contributions of this paper. First, we provide full derivation of the EM adaptation algorithm and demonstrate methods to improve the computational complexity. Second, in the absence of the latent clean image, we show how EM adaptation can be modified based on pre-filtering. The experimental results show that the proposed adaptation algorithm yields consistently better denoising results than the one without adaptation and is superior to several state-of-the-art algorithms.

  18. Acta Clinica Croatica: progress of a journal step by step.

    PubMed

    Ramljak, Gordana

    2014-03-01

    The journal Acta Clinica Croatica (ACC) was founded in 1962 under the title Anali Bolnice Dr. M. Stojanović. In 1995, the title of the journal was changed into its present form and ever since all papers have been published in English. In 2000, the electronic (online) edition of the ACC was released in addition to the print version. The paper presents development of the journal from 1962 to 2012 based on the analysis of the following SCOPUS citation index parameters: type and number of documents published in the journal; number of citations; and number of domestic and foreign authors. The studied period was analyzed in three time segments: the period from 1995 to 1999, the period from 2000 to 2006 and the period from 2007 to 2012. The same parameters were analyzed in the Web of Science/SCI-Expanded bibliographic and citation index for the 2007-2012 period. The increasing number of documents, authors (both domestic and foreign) and citations demonstrates gradual rise in the quality, visibility and impact of the journal. The fifty years of experience show that a goal, at first very distant and almost unachievable, may be reached by progressing step by step.

  19. Adaptive boxcar/wavelet transform

    NASA Astrophysics Data System (ADS)

    Sezer, Osman G.; Altunbasak, Yucel

    2009-01-01

    This paper presents a new adaptive Boxcar/Wavelet transform for image compression. Boxcar/Wavelet decomposition emphasizes the idea of average-interpolation representation which uses dyadic averages and their interpolation to explain a special case of biorthogonal wavelet transforms (BWT). This perspective for image compression together with lifting scheme offers the ability to train an optimum 2-D filter set for nonlinear prediction (interpolation) that will adapt to the context around the low-pass wavelet coefficients for reducing energy in the high-pass bands. Moreover, the filters obtained after training is observed to posses directional information with some textural clues that can provide better prediction performance. This work addresses a firrst step towards obtaining this new set of training-based fillters in the context of Boxcar/Wavelet transform. Initial experimental results show better subjective quality performance compared to popular 9/7-tap and 5/3-tap BWTs with comparable results in objective quality.

  20. First steps towards a scatterometry reference standard

    NASA Astrophysics Data System (ADS)

    Bodermann, Bernd; Hansen, Poul-Erik; Burger, Sven; Henn, Mark-Alexander; Gross, Hermann; Bär, Markus; Scholze, Frank; Endres, Johannes; Wurm, Matthias

    2012-10-01

    Supported by the European Commission and EURAMET, a consortium of 10 participants from national metrology institutes, universities and companies has recently started a joint research project with the aim of overcoming current challenges in optical scatterometry for traceable linewidth metrology and to establish scatterometry as a traceable and absolute metrological method for dimensional measurements. This requires a thorough investigation of the influence of all significant sample, tool and data analysis parameters, which affect the scatterometric measurement results. For this purpose and to improve the tool matching between scatterometers, CD-SEMs and CD-AFMs, experimental and modelling methods will be enhanced. The different scatterometry methods will be compared with each other and with specially adapted atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurement systems. Additionally novel methods for sophisticated data analysis will be developed and investigated to reach significant reductions of the measurement uncertainties in critical dimension (CD) metrology. To transfer traceability to industrial applications of scatterometry an important step and one final goal of this project is the realisation of different waferbased reference standard materials for calibration of scatterometers. The approaches to reach these goals and first design considerations and preliminary specification of the scatterometry standards are presented and discussed.

  1. Composite-step product methods for solving nonsymmetric linear systems

    SciTech Connect

    Chan, T.F.; Szeto, T.

    1994-12-31

    The Biconjugate Gradient (BCG) algorithm is the {open_quotes}natural{close_quotes} generalization of the classical Conjugate Gradient method to nonsymmetric linear systems. It is an attractive method because of its simplicity and its good convergence properties. Unfortunately, BCG suffers from two kinds of breakdowns (divisions by 0): one due to the non-existence of the residual polynomial, and the other due to a breakdown in the recurrence relationship used. There are many look-ahead techniques in existence which are designed to handle these breakdowns. Although the step size needed to overcome an exact breakdown can be computed in principle, these methods can unfortunately be quite complicated for handling near breakdowns since the sizes of the look-ahead steps are variable (indeed, the breakdowns can be incurable). Recently, Bank and Chan introduced the Composite Step Biconjugate Gradient (CSBCG) algorithm, an alternative which cures only the first of the two breakdowns mentioned by skipping over steps for which the BCG iterate is not defined. This is done with a simple modification of BCG which needs only a maximum look-ahead step size of 2 to eliminate the (near) breakdown and to smooth the sometimes erratic convergence of BCG. Thus, instead of a more complicated (but less prone to breakdown) version, CSBCG cures only one kind of breakdown, but does so with a minimal modification to the usual implementation of BCG in the hope that its empirically observed stability will be inherited. The authors note, then, that the Composite Step idea can be incorporated anywhere the BCG polynomial is used; in particular, in product methods such as CGS, Bi-CGSTAB, and TFQMR. Doing this not only cures the breakdown mentioned above, but also takes on the advantages of these product methods, namely, no multiplications by the transpose matrix and a faster convergence rate than BCG.

  2. Adapting the ALP Model for Student and Institutional Needs

    ERIC Educational Resources Information Center

    Sides, Meredith

    2016-01-01

    With the increasing adoption of accelerated models of learning comes the necessary step of adapting these models to fit the unique needs of the student population at each individual institution. One such college adapted the ALP (Accelerated Learning Program) model and made specific changes to the target population, structure and scheduling, and…

  3. Beyond Reduction: Climate Change Adaptation Planning for Universities and Colleges

    ERIC Educational Resources Information Center

    Owen, Rochelle; Fisher, Erica; McKenzie, Kyle

    2013-01-01

    Purpose: The purpose of this paper is to outline a unique six-step process for the inclusion of climate change adaption goals and strategies in a University Climate Change Plan. Design/methodology/approach: A mixed-method approach was used to gather data on campus climate change vulnerabilities and adaption strategies. A literature review…

  4. Step-by-Step Simulation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    Radiolytic species are formed approximately 1 ps after the passage of ionizing radiation through matter. After their formation, they diffuse and chemically react with other radiolytic species and neighboring biological molecules, leading to various oxidative damage. Therefore, the simulation of radiation chemistry is of considerable importance to understand how radiolytic species damage biological molecules [1]. The step-by-step simulation of chemical reactions is difficult, because the radiolytic species are distributed non-homogeneously in the medium. Consequently, computational approaches based on Green functions for diffusion-influenced reactions should be used [2]. Recently, Green functions for more complex type of reactions have been published [3-4]. We have developed exact random variate generators of these Green functions [5], which will allow us to use them in radiation chemistry codes. Moreover, simulating chemistry using the Green functions is which is computationally very demanding, because the probabilities of reactions between each pair of particles should be evaluated at each timestep [2]. This kind of problem is well adapted for General Purpose Graphic Processing Units (GPGPU), which can handle a large number of similar calculations simultaneously. These new developments will allow us to include more complex reactions in chemistry codes, and to improve the calculation time. This code should be of importance to link radiation track structure simulations and DNA damage models.

  5. Step-length biofeedback device for walk rehabilitation.

    PubMed

    Montoya, R; Dupui, P; Pagès, B; Bessou, P

    1994-07-01

    A biofeedback gait training system for step length is proposed, adapted to the correction of spatial walking asymmetries by means of a simple, quick and reliable method for daily clinical use. The system is composed of a walkway and a gait analysis device (locometer) measuring the main temporal and distance factors of gait. The step length is imposed on the subject by lighted targets appearing on the walkway, alternately on the right and left side; the subject is asked to place a swinging foot on the lighted target. Feedback to the subject is supplied by direct visual information (the subject looking at the movement and the position of the foot with respect to the lighted target) and an acoustic signal delivered in real time when the length step error is greater than an allowed value. The method is validated on a population of hemiparetic patients who have suffered from a stroke and who have been reeducated with traditional rehabilitation methods. The patients were divided into two groups; one group following a gait training with biofeedback (BFB group) and one group following a gait training without biofeedback (reference group). Preliminary results are presented, showing a significant beneficial effect of the biofeedback method in increasing the step length of paretic limbs and in correcting step-length asymmetry.

  6. Lessons learned in stepped chute research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Early research on stepped chutes focused on steep gravity style stepped chutes. Today, the research trend has shifted to stepped chutes applied to more moderate slopes like those for aging embankment dams. Research contributions have been made on hydraulic properties of stepped chutes including ai...

  7. Hydraulic Design of Stepped Spillways Workshop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stepped chutes and spillways are commonly used for routing discharges during flood events. In addition, stepped chutes are used for overtopping protection of earthen embankments. Stepped spillways provide significant energy dissipation due to its stepped feature; as a result, the stilling basin as...

  8. Research on test of product based on spatial sampling criteria and variable step sampling mechanism

    NASA Astrophysics Data System (ADS)

    Li, Ruihong; Han, Yueping

    2014-09-01

    This paper presents an effective approach for online testing the assembly structures inside products using multiple views technique and X-ray digital radiography system based on spatial sampling criteria and variable step sampling mechanism. Although there are some objects inside one product to be tested, there must be a maximal rotary step for an object within which the least structural size to be tested is predictable. In offline learning process, Rotating the object by the step and imaging it and so on until a complete cycle is completed, an image sequence is obtained that includes the full structural information for recognition. The maximal rotary step is restricted by the least structural size and the inherent resolution of the imaging system. During online inspection process, the program firstly finds the optimum solutions to all different target parts in the standard sequence, i.e., finds their exact angles in one cycle. Aiming at the issue of most sizes of other targets in product are larger than that of the least structure, the paper adopts variable step-size sampling mechanism to rotate the product specific angles with different steps according to different objects inside the product and match. Experimental results show that the variable step-size method can greatly save time compared with the traditional fixed-step inspection method while the recognition accuracy is guaranteed.

  9. Step-reduced synthesis of starch-silver nanoparticles.

    PubMed

    Raghavendra, Gownolla Malegowd; Jung, Jeyoung; Kim, Dowan; Seo, Jongchul

    2016-05-01

    In the present process, silver nanoparticles were directly synthesized in a single step by microwave irradiation of a mixture of starch, silver nitrate, and deionized water. This is different from the commonly adopted procedure for starch-silver nanoparticle synthesis in which silver nanoparticles are synthesized by preparing a starch solution as a reaction medium first. Thus, the additional step associated with the preparation of the starch solution was eliminated. In addition, no additional reducing agent was utilized. The adopted method was facile and straight forward, affording spherical silver nanoparticles with diameter below 10nm that exhibited good antibacterial activity. Further, influence of starch on the size of the silver nanoparticles was noticed.

  10. One-step fabrication of supramolecular microcapsules from microfluidic droplets.

    PubMed

    Zhang, Jing; Coulston, Roger J; Jones, Samuel T; Geng, Jin; Scherman, Oren A; Abell, Chris

    2012-02-10

    Although many techniques exist for preparing microcapsules, it is still challenging to fabricate them in an efficient and scalable process without compromising functionality and encapsulation efficiency. We demonstrated a simple one-step approach that exploits a versatile host-guest system and uses microfluidic droplets to generate porous microcapsules with easily customizable functionality. The capsules comprise a polymer-gold nanoparticle composite held together by cucurbit[8]uril ternary complexes. The dynamic yet highly stable micrometer-sized structures can be loaded in one step during capsule formation and are amenable to on-demand encapsulant release. The internal chemical environment can be probed with surface enhanced Raman spectroscopy.

  11. Adapting lean to histology laboratories.

    PubMed

    Buesa, René J

    2009-10-01

    Histology laboratories (histolabs) can increase productivity and reduce turnaround time and errors by using any one of several available management tools. After a few years of operation, all histolabs develop workflow problems. Histology laboratories handling more than 20,000 cases per year benefit the most from implementing management tools, as occurred in the 25 facilities summarized in this article. Discontinuous workflow, lack of "pulling" between steps, accepting unavoidable waiting times while working with small batches within work cells, and a workflow with an uneven rate of completion, are some of the adaptations required by the Lean system when it is used in histology because 70% of the tasks are manual and the flow has to be interrupted to add value to the pieces of tissue during tissue processing, no matter how short that step is. After all these adaptations are incorporated, the histolab becomes as "Lean" as it can be, and the qualifier is also a recognition of the effort and personnel involvement in the implementation. Given its service nature, productivity increments do not expand the histolab customer base and could lead to staffing reductions. This is one of the causes of reluctance by some employees for implementing these techniques which are mostly driven by cost reductions sought by insurance companies and administrators, and not necessarily because of a real medical need to reduce the turnaround time. Finally, any histolab wanting to improve its workflow can follow some easy steps presented here as a guide to accomplish that objective. These steps stress the need for the supervisors to insure that the personnel in the histology laboratory are being paid at a comparable rate as other histolabs in the area.

  12. A Caenorhabditis elegans wild type defies the temperature-size rule owing to a single nucleotide polymorphism in tra-3.

    PubMed

    Kammenga, Jan E; Doroszuk, Agnieszka; Riksen, Joost A G; Hazendonk, Esther; Spiridon, Laurentiu; Petrescu, Andrei-Jose; Tijsterman, Marcel; Plasterk, Ronald H A; Bakker, Jaap

    2007-03-02

    Ectotherms rely for their body heat on surrounding temperatures. A key question in biology is why most ectotherms mature at a larger size at lower temperatures, a phenomenon known as the temperature-size rule. Since temperature affects virtually all processes in a living organism, current theories to explain this phenomenon are diverse and complex and assert often from opposing assumptions. Although widely studied, the molecular genetic control of the temperature-size rule is unknown. We found that the Caenorhabditis elegans wild-type N2 complied with the temperature-size rule, whereas wild-type CB4856 defied it. Using a candidate gene approach based on an N2 x CB4856 recombinant inbred panel in combination with mutant analysis, complementation, and transgenic studies, we show that a single nucleotide polymorphism in tra-3 leads to mutation F96L in the encoded calpain-like protease. This mutation attenuates the ability of CB4856 to grow larger at low temperature. Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain. The data show that size adaptation of ectotherms to temperature changes may be less complex than previously thought because a subtle wild-type polymorphism modulates the temperature responsiveness of body size. These findings provide a novel step toward the molecular understanding of the temperature-size rule, which has puzzled biologists for decades.

  13. Age-Related Differences in Locomotor Strategies During Adaptive Walking.

    PubMed

    Lowry, Kristin A; Sebastian, Katherine; Perera, Subashan; Van Swearingen, Jessie; Smiley-Oyen, Ann L

    2016-11-21

    Simultaneous control of lower limb stepping movements and trunk motion is important for skilled walking; adapting gait to environmental constraints requires frequent alternations in stepping and trunk motion. These alterations provide a window into the locomotor strategies adopted by the walker. The authors examined gait strategies in young and healthy older adults when manipulating step width. Anteroposterior (AP) and mediolateral (ML) smoothness (quantified by harmonic ratios) and stepping consistency (quantified by gait variability) were analyzed during narrow and wide walking while controlling cadence to preferred pace. Results indicated older adults preserved ML smoothness at the expense of AP smoothness, shortened their steps, and exhibited reduced stepping consistency. The authors conclude that older adults prioritized ML control over forward progression during adaptive walking challenges.

  14. Adaptive statistical pattern classifiers for remotely sensed data

    NASA Technical Reports Server (NTRS)

    Gonzalez, R. C.; Pace, M. O.; Raulston, H. S.

    1975-01-01

    A technique for the adaptive estimation of nonstationary statistics necessary for Bayesian classification is developed. The basic approach to the adaptive estimation procedure consists of two steps: (1) an optimal stochastic approximation of the parameters of interest and (2) a projection of the parameters in time or position. A divergence criterion is developed to monitor algorithm performance. Comparative results of adaptive and nonadaptive classifier tests are presented for simulated four dimensional spectral scan data.

  15. What Promotes Wisdom in 12-Step Recovery?

    PubMed

    DiGangi, Julia A; Majer, John M; Mendoza, Leslie; Droege, Jocelyn R; Jason, Leonard A; Contreras, Richard

    2014-01-01

    Research investigations on twelve-step groups such as Alcoholics Anonymous (AA) and Narcotics Anonymous (NA) have addressed a number of resources associated with 12-step recovery. However, little is known about the role of wisdom, and whether aspects of 12-step participation might increase this resource among 12-step members. An exploratory analysis revealed that participants who reported having a "spiritual awakening" and considered themselves "members" of 12-step groups reported significantly higher levels of wisdom. Twelve-step meeting attendance was not significantly related to wisdom scores. Findings suggest certain aspects of 12-step involvement are associated with wisdom and may play a role in substance abuse recovery.

  16. Step-induced magnetic anisotropy in Co/stepped Cu(001) as a function of step density and Cu step decoration

    SciTech Connect

    Kawakami, R.K.; Bowen, M.O.; Choi, H.J.; Escorcia-Aparicio, E.J.; Qiu, Z.Q.

    1999-04-01

    The step-induced in-plane uniaxial magnetic anisotropy of fcc Co/stepped Cu(001) was investigated using a curved substrate to provide a continuous range of vicinal angles from 0{degree} to 6{degree}. The anisotropy strength was found to depend linearly on the step density, indicating that the biaxial strain does not make a significant contribution to the step-induced anisotropy. Using a side growth geometry to decorate the Co step edges with Cu adsorbates, we observed that the step-induced anisotropy strength approaches zero at roughly 0.7 atomic rows of Cu, independent of step density. {copyright} {ital 1999 American Institute of Physics.}

  17. Hybrid adaptive ascent flight control for a flexible launch vehicle

    NASA Astrophysics Data System (ADS)

    Lefevre, Brian D.

    hybrid adaptive flight controller, development of a Newton's method based online parameter update that is modified to include a step size which regulates the rate of change in the parameter estimates, comparison of the modified Newton's method and recursive least squares online parameter update algorithms, modification of the neural network's input structure to accommodate for the nature of the nonlinearities present in a launch vehicle's ascent flight, examination of both tracking error based and modeling error based neural network weight update laws, and integration of feedback filters for the purpose of preventing harmful interaction between the flight control system and flexible structural modes. To validate the hybrid adaptive controller, a high-fidelity Ares I ascent flight simulator and a classical gain-scheduled proportional-integral-derivative (PID) ascent flight controller were obtained from the NASA Marshall Space Flight Center. The classical PID flight controller is used as a benchmark when analyzing the performance of the hybrid adaptive flight controller. Simulations are conducted which model both nominal and off-nominal flight conditions with structural flexibility of the vehicle either enabled or disabled. First, rigid body ascent simulations are performed with the hybrid adaptive controller under nominal flight conditions for the purpose of selecting the update laws which drive the indirect and direct adaptive components. With the neural network disabled, the results revealed that the recursive least squares online parameter update caused high frequency oscillations to appear in the engine gimbal commands. This is highly undesirable for long and slender launch vehicles, such as the Ares I, because such oscillation of the rocket nozzle could excite unstable structural flex modes. In contrast, the modified Newton's method online parameter update produced smooth control signals and was thus selected for use in the hybrid adaptive launch vehicle flight

  18. Immersed Boundary Fractional Step Method

    NASA Astrophysics Data System (ADS)

    Taira, Kunihiko

    2005-11-01

    We present a new formulation of the immersed boundary method for incompressible flow over moving rigid bodies. Like many existing techniques we introduce a set of interpolation points on the surface at which the no-slip boundary condition is satisfied by including a (regularized) force in the momentum equations. By introducing interpolation and regularization operators and grouping pressure and force unknowns together, the discretized Navier-Stokes equations with the immersed boundary method can be formulated with an identical structure to the traditional fractional step method, but with a modified Poisson equation whose unknowns are both the pressure and the boundary force. The method highlights the analogous roles of pressure and boundary forcing as Lagrange multipliers in order to satisfy the divergence free and no-slip constraints, respectively. The overall method is found to be a simple addition to an existing fractional step code and the extended Poisson equation is solved efficiently with the conjugate gradient method. We demonstrate convergence and present results for two-dimensional flows with a variety of moving rigid bodies.

  19. On Effect Size

    ERIC Educational Resources Information Center

    Kelley, Ken; Preacher, Kristopher J.

    2012-01-01

    The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension,…

  20. Automated measurement of diatom size

    USGS Publications Warehouse

    Spaulding, Sarah A.; Jewson, David H.; Bixby, Rebecca J.; Nelson, Harry; McKnight, Diane M.

    2012-01-01

    Size analysis of diatom populations has not been widely considered, but it is a potentially powerful tool for understanding diatom life histories, population dynamics, and phylogenetic relationships. However, measuring cell dimensions on a light microscope is a time-consuming process. An alternative technique has been developed using digital flow cytometry on a FlowCAM® (Fluid Imaging Technologies) to capture hundreds, or even thousands, of images of a chosen taxon from a single sample in a matter of minutes. Up to 30 morphological measures may be quantified through post-processing of the high resolution images. We evaluated FlowCAM size measurements, comparing them against measurements from a light microscope. We found good agreement between measurement of apical cell length in species with elongated, straight valves, including small Achnanthidium minutissimum (11-21 µm) and largeDidymosphenia geminata (87–137 µm) forms. However, a taxon with curved cells, Hannaea baicalensis (37–96 µm), showed differences of ~ 4 µm between the two methods. Discrepancies appear to be influenced by the choice of feret or geodesic measurement for asymmetric cells. We describe the operating conditions necessary for analysis of size distributions and present suggestions for optimal instrument conditions for size analysis of diatom samples using the FlowCAM. The increased speed of data acquisition through use of imaging flow cytometers like the FlowCAM is an essential step for advancing studies of diatom populations.

  1. Tropically adapted cattle of Africa: perspectives on potential role of copy number variations.

    PubMed

    Wang, M D; Dzama, K; Rees, D J G; Muchadeyi, F C

    2016-04-01

    Africa is host to diverse and locally adapted cattle breeds that are expected to survive the harsh and extreme tropical environments associated with diseases and parasite infections, heat stress and episodes of feed and water scarcity. Genomic copy number variations (CNVs) are considered to be primary role players in cattle breed formation and adaptation where isolation and genetic drift together with subsequent mutations have created an enormous diversity of local populations. CNVs are modifications in DNA structure comprising deletions, duplications and insertions that are >1 kb in size. Despite attracting much attention, the frequency and pattern of bovine CNV events, especially in African cattle breeds, are for the most part largely unknown. Characterization of genetic variation in the indigenous cattle of Africa will be a vital step toward dissecting the molecular mechanisms underlying phenotypic variation and local adaptation. This review therefore aims to describe the current knowledge regarding bovine CNVs and the implications and potentials they encompass for dissecting genetic adaptation and the genotypic skeleton of tropical African cattle populations.

  2. Astronomical image denoising by means of improved adaptive backtracking-based matching pursuit algorithm.

    PubMed

    Liu, Qianshun; Bai, Jian; Yu, Feihong

    2014-11-10

    In an effort to improve compressive sensing and spare signal reconstruction by way of the backtracking-based adaptive orthogonal matching pursuit (BAOMP), a new sparse coding algorithm called improved adaptive backtracking-based OMP (ABOMP) is proposed in this study. Many aspects have been improved compared to the original BAOMP method, including replacing the fixed threshold with an adaptive one, adding residual feedback and support set verification, and others. Because of these ameliorations, the proposed algorithm can more precisely choose the atoms. By adding the adaptive step-size mechanism, it requires much less iteration and thus executes more efficiently. Additionally, a simple but effective contrast enhancement method is also adopted to further improve the denoising results and visual effect. By combining the IABOMP algorithm with the state-of-art dictionary learning algorithm K-SVD, the proposed algorithm achieves better denoising effects for astronomical images. Numerous experimental results show that the proposed algorithm performs successfully and effectively on Gaussian and Poisson noise removal.

  3. Habituation of visual adaptation

    PubMed Central

    Dong, Xue; Gao, Yi; Lv, Lili; Bao, Min

    2016-01-01

    Our sensory system adjusts its function driven by both shorter-term (e.g. adaptation) and longer-term (e.g. learning) experiences. Most past adaptation literature focuses on short-term adaptation. Only recently researchers have begun to investigate how adaptation changes over a span of days. This question is important, since in real life many environmental changes stretch over multiple days or longer. However, the answer to the question remains largely unclear. Here we addressed this issue by tracking perceptual bias (also known as aftereffect) induced by motion or contrast adaptation across multiple daily adaptation sessions. Aftereffects were measured every day after adaptation, which corresponded to the degree of adaptation on each day. For passively viewed adapters, repeated adaptation attenuated aftereffects. Once adapters were presented with an attentional task, aftereffects could either reduce for easy tasks, or initially show an increase followed by a later decrease for demanding tasks. Quantitative analysis of the decay rates in contrast adaptation showed that repeated exposure of the adapter appeared to be equivalent to adaptation to a weaker stimulus. These results suggest that both attention and a non-attentional habituation-like mechanism jointly determine how adaptation develops across multiple daily sessions. PMID:26739917

  4. VisAdapt: A Visualization Tool to Support Climate Change Adaptation.

    PubMed

    Johansson, Jimmy; Opach, Tomasz; Glaas, Erik; Neset, Tina-Simone; Navarra, Carlo; Linner, Bjorn-Ola; Rod, Jan Ketil

    2017-01-01

    The web-based visualization VisAdapt tool was developed to help laypeople in the Nordic countries assess how anticipated climate change will impact their homes. The tool guides users through a three-step visual process that helps them explore risks and identify adaptive actions specifically modified to their location and house type. This article walks through the tool's multistep, user-centered design process. Although VisAdapt's target end users are Nordic homeowners, the insights gained from the development process and the lessons learned from the project are applicable to a wide range of domains.

  5. Sleep facilitates long-term face adaptation.

    PubMed

    Ditye, Thomas; Javadi, Amir Homayoun; Carbon, Claus-Christian; Walsh, Vincent

    2013-10-22

    Adaptation is an automatic neural mechanism supporting the optimization of visual processing on the basis of previous experiences. While the short-term effects of adaptation on behaviour and physiology have been studied extensively, perceptual long-term changes associated with adaptation are still poorly understood. Here, we show that the integration of adaptation-dependent long-term shifts in neural function is facilitated by sleep. Perceptual shifts induced by adaptation to a distorted image of a famous person were larger in a group of participants who had slept (experiment 1) or merely napped for 90 min (experiment 2) during the interval between adaptation and test compared with controls who stayed awake. Participants' individual rapid eye movement sleep duration predicted the size of post-sleep behavioural adaptation effects. Our data suggest that sleep prevented decay of adaptation in a way that is qualitatively different from the effects of reduced visual interference known as 'storage'. In the light of the well-established link between sleep and memory consolidation, our findings link the perceptual mechanisms of sensory adaptation--which are usually not considered to play a relevant role in mnemonic processes--with learning and memory, and at the same time reveal a new function of sleep in cognition.

  6. Moral transhumanism: the next step.

    PubMed

    Tennison, Michael N

    2012-08-01

    Although transhumanism offers hope for the transcendence of human biological limitations, it generates many intrinsic and consequential ethical concerns. The latter include issues such as the exacerbation of social inequalities and the exponentially increasing technological capacity to cause harm. To mitigate these risks, many thinkers have initiated investigations into the possibility of moral enhancement that could limit the power disparities facilitated by biotechnological enhancement. The arguments often focus on whether moral enhancement is morally permissible, or even obligatory, and remain largely in the realm of the hypothetical. This paper proposes that psilocybin may represent a viable, practical option for moral enhancement and that its further research in the context of moral psychology could comprise the next step in the development of moral transhumanism.

  7. Perturbations of ground support alter posture and locomotion coupling during step initiation in Parkinson's disease.

    PubMed

    Rogers, Mark W; Hilliard, Marjorie Johnson; Martinez, Katherine M; Zhang, Yunhui; Simuni, Tanya; Mille, Marie-Laure

    2011-02-01

    During the initiation of stepping, anticipatory postural adjustments (APAs) for lateral weight transfer and propulsion normally precede the onset of locomotion. In Parkinson's disease (PD), impaired step initiation typically involves altered APA ground force production with delayed step onset and deficits in stepping performance. If, as in stance and gait, sensory information about lower limb load is important for the control of stepping, then perturbations influencing loading conditions could affect the step initiation process. This study investigated the influence of changes in lower limb loading during step initiation in patients with PD and healthy control subjects. Participants performed rapid self-triggered step initiation with the impending single stance limb positioned over a pneumatically actuated platform. In perturbation trials, the stance limb ground support surface was either moved vertically downward (DROP) or upward (ELEVATE) by 1.5 cm shortly after the onset of the APA phase. Overall, PD patients demonstrated a longer APA duration, longer time to first step onset, and slower step speed than controls. In both groups, the DROP perturbation reinforced the intended APA kinetic changes for lateral weight transfer and resulted in a significant reduction in APA duration, increase in peak amplitude, and earlier time to first step onset compared with other conditions. During ELEVATE trials that opposed the intended weight transfer forces both groups rapidly adapted their stepping to preserve standing stability by decreasing step length and duration, and increasing step height and foot placement laterally. The findings suggested that sensory information associated with limb load and/or foot pressure modulates the spatial and temporal parameters of posture and locomotion components of step initiation in interaction with a centrally generated feedforward mode of neural control. Moreover, impaired step initiation in PD may at least acutely be enhanced by

  8. Adaptive tracking of narrowband HF channel response

    NASA Astrophysics Data System (ADS)

    Arikan, F.; Arikan, O.

    2003-12-01

    Estimation of channel impulse response constitutes a first step in computation of scattering function, channel equalization, elimination of multipath, and optimum detection and identification of transmitted signals through the HF channel. Due to spatial and temporal variations, HF channel impulse response has to be estimated adaptively. Based on developed state-space and measurement models, an adaptive Kalman filter is proposed to track the HF channel variation in time. Robust methods of initialization and adaptively adjusting the noise covariance in the system dynamics are proposed. In simulated examples under good, moderate and poor ionospheric conditions, it is observed that the adaptive Kalman filter based channel estimator provides reliable channel estimates and can track the variation of the channel in time with high accuracy.

  9. Development of Underwater Laser Scaling Adapter

    NASA Astrophysics Data System (ADS)

    Bluss, Kaspars

    2012-12-01

    In this paper the developed laser scaling adapter is presented. The scaling adapter is equipped with a twin laser unit where the two parallel laser beams are projected onto any target giving an exact indication of scale. The body of the laser scaling adapter is made of Teflon, the density of which is approximately two times the water density. The development involved multiple challenges - numerical hydrodynamic calculations for choosing an appropriate shape which would reduce the effects of turbulence, an accurate sealing of the power supply and the laser diodes, and others. The precision is estimated by the partial derivation method. Both experimental and theoretical data conclude the overall precision error to be in the 1% margin. This paper presents the development steps of such an underwater laser scaling adapter for a remotely operated vehicle (ROV).

  10. Optical Profilometers Using Adaptive Signal Processing

    NASA Technical Reports Server (NTRS)

    Hall, Gregory A.; Youngquist, Robert; Mikhael, Wasfy

    2006-01-01

    A method of adaptive signal processing has been proposed as the basis of a new generation of interferometric optical profilometers for measuring surfaces. The proposed profilometers would be portable, hand-held units. Sizes could be thus reduced because the adaptive-signal-processing method would make it possible to substitute lower-power coherent light sources (e.g., laser diodes) for white light sources and would eliminate the need for most of the optical components of current white-light profilometers. The adaptive-signal-processing method would make it possible to attain scanning ranges of the order of decimeters in the proposed profilometers.

  11. Forecasting Sensorimotor Adaptability from Baseline Inter-Trial Correlations

    NASA Technical Reports Server (NTRS)

    Beaton, K. H.; Bloomberg, J. J.

    2014-01-01

    One of the greatest challenges surrounding adaptation to the spaceflight environment is the large variability in symptoms, and corresponding functional impairments, from one crewmember to the next. This renders preflight training and countermeasure development difficult, as a "one-size-fits-all" approach is inappropriate. Therefore, it would be highly advantageous to know ahead of time which crewmembers might have more difficulty adjusting to the novel g-levels inherent to spaceflight. Such knowledge could guide individually customized countermeasures, which would enable more efficient use of crew time, both preflight and inflight, and provide better outcomes. The primary goal of this project is to look for a baseline performance metric that can forecast sensorimotor adaptability without exposure to an adaptive stimulus. We propose a novel hypothesis that considers baseline inter-trial correlations, the trial-to-trial fluctuations in motor performance, as a predictor of individual sensorimotor adaptive capabilities. To-date, a strong relationship has been found between baseline inter-trial correlations and adaptability in two oculomotor systems. For this project, we will explore an analogous predictive mechanism in the locomotion system. METHODS: Baseline Inter-trial Correlations: Inter-trial correlations specify the relationships among repeated trials of a given task that transpire as a consequence of correcting for previous performance errors over multiple timescales. We can quantify the strength of inter-trial correlations by measuring the decay of the autocorrelation function (ACF), which describes how rapidly information from past trials is "forgotten." Processes whose ACFs decay more slowly exhibit longer-term inter-trial correlations (longer memory processes), while processes whose ACFs decay more rapidly exhibit shorterterm inter-trial correlations (shorter memory processes). Longer-term correlations reflect low-frequency activity, which is more easily

  12. Topographic ERP analyses: a step-by-step tutorial review.

    PubMed

    Murray, Micah M; Brunet, Denis; Michel, Christoph M

    2008-06-01

    In this tutorial review, we detail both the rationale for as well as the implementation of a set of analyses of surface-recorded event-related potentials (ERPs) that uses the reference-free spatial (i.e. topographic) information available from high-density electrode montages to render statistical information concerning modulations in response strength, latency, and topography both between and within experimental conditions. In these and other ways these topographic analysis methods allow the experimenter to glean additional information and neurophysiologic interpretability beyond what is available from canonical waveform analyses. In this tutorial we present the example of somatosensory evoked potentials (SEPs) in response to stimulation of each hand to illustrate these points. For each step of these analyses, we provide the reader with both a conceptual and mathematical description of how the analysis is carried out, what it yields, and how to interpret its statistical outcome. We show that these topographic analysis methods are intuitive and easy-to-use approaches that can remove much of the guesswork often confronting ERP researchers and also assist in identifying the information contained within high-density ERP datasets.

  13. A Step by Step Protocol for Subretinal Surgery in Rabbits

    PubMed Central

    Al-Nawaiseh, Sami; Thieltges, Fabian; Liu, Zengping; Strack, Claudine; Brinken, Ralf; Braun, Norbert; Wolschendorf, Marc; Maminishkis, Arvydas; Eter, Nicole; Stanzel, Boris V.

    2016-01-01

    Age related macular degeneration (AMD), retinitis pigmentosa, and other RPE related diseases are the most common causes for irreversible loss of vision in adults in industrially developed countries. RPE transplantation appears to be a promising therapy, as it may replace dysfunctional RPE, restore its function, and thereby vision. Here we describe a method for transplanting a cultured RPE monolayer on a scaffold into the subretinal space (SRS) of rabbits. After vitrectomy xenotransplants were delivered into the SRS using a custom made shooter consisting of a 20-gauge metallic nozzle with a polytetrafluoroethylene (PTFE) coated plunger. The current technique evolved in over 150 rabbit surgeries over 6 years. Post-operative follow-up can be obtained using non-invasive and repetitive in vivo imaging such as spectral domain optical coherence tomography (SD-OCT) followed by perfusion-fixed histology. The method has well-defined steps for easy learning and high success rate. Rabbits are considered a large eye animal model useful in preclinical studies for clinical translation. In this context rabbits are a cost-efficient and perhaps convenient alternative to other large eye animal models. PMID:27684952

  14. A Step by Step Protocol for Subretinal Surgery in Rabbits.

    PubMed

    Al-Nawaiseh, Sami; Thieltges, Fabian; Liu, Zengping; Strack, Claudine; Brinken, Ralf; Braun, Norbert; Wolschendorf, Marc; Maminishkis, Arvydas; Eter, Nicole; Stanzel, Boris V

    2016-09-13

    Age related macular degeneration (AMD), retinitis pigmentosa, and other RPE related diseases are the most common causes for irreversible loss of vision in adults in industrially developed countries. RPE transplantation appears to be a promising therapy, as it may replace dysfunctional RPE, restore its function, and thereby vision. Here we describe a method for transplanting a cultured RPE monolayer on a scaffold into the subretinal space (SRS) of rabbits. After vitrectomy xenotransplants were delivered into the SRS using a custom made shooter consisting of a 20-gauge metallic nozzle with a polytetrafluoroethylene (PTFE) coated plunger. The current technique evolved in over 150 rabbit surgeries over 6 years. Post-operative follow-up can be obtained using non-invasive and repetitive in vivo imaging such as spectral domain optical coherence tomography (SD-OCT) followed by perfusion-fixed histology. The method has well-defined steps for easy learning and high success rate. Rabbits are considered a large eye animal model useful in preclinical studies for clinical translation. In this context rabbits are a cost-efficient and perhaps convenient alternative to other large eye animal models.

  15. Incremental exposure facilitates adaptation to sensory rearrangement. [vestibular stimulation patterns

    NASA Technical Reports Server (NTRS)

    Lackner, J. R.; Lobovits, D. N.

    1978-01-01

    Visual-target pointing experiments were performed on 24 adult volunteers in order to compare the relative effectiveness of incremental (stepwise) and single-step exposure conditions on adaptation to visual rearrangement. The differences between the preexposure and postexposure scores served as an index of the adaptation elicited during the exposure period. It is found that both single-step and stepwise exposure to visual rearrangement elicit compensatory changes in sensorimotor coordination. However, stepwise exposure, when compared to single-step exposur in terms of the average magnitude of visual displacement over the exposure period, clearly enhances the rate of adaptation. It seems possible that the enhancement of adaptation to unusual patterns of sensory stimulation produced by incremental exposure reflects a general principle of sensorimotor function.

  16. Considerations when calculating the sample size for an inequality test

    PubMed Central

    2016-01-01

    Click here for Korean Translation. Calculating the sample size is a vital step during the planning of a study in order to ensure the desired power for detecting clinically meaningful differences. However, estimating the sample size is not always straightforward. A number of key components should be considered to calculate a suitable sample size. In this paper, general considerations for conducting sample size calculations for inequality tests are summarized. PMID:27482308

  17. Considerations when calculating the sample size for an inequality test.

    PubMed

    In, Junyong

    2016-08-01

    Click here for Korean Translation. Calculating the sample size is a vital step during the planning of a study in order to ensure the desired power for detecting clinically meaningful differences. However, estimating the sample size is not always straightforward. A number of key components should be considered to calculate a suitable sample size. In this paper, general considerations for conducting sample size calculations for inequality tests are summarized.

  18. Kinematic analysis of step ascent among patients with central visual field loss.

    PubMed

    Timmis, Matthew A; Scarfe, Amy C; Tabrett, Daryl R; Pardhan, Shahina

    2014-01-01

    Vision is of paramount importance in regulating adaptive gait. Using three-dimensional motion analysis, the current study investigated how central visual field loss (CFL) affects step ascent. Ten patients with chronic CFL (77 ± 10 years) and 13 visual normal participants (72 ± 6 years) walked up to and ascended a single step (of varying height). Movement kinematics assessed the period immediately prior to and during step ascent. Compared to visual normal participants, patients with CFL exhibited a lower lead foot horizontal crossing velocity, increased lead limb swing time and increased head flexion (looking down at more immediate areas of the ground/step). They also took longer to initiate the step up, transfer weight to the lead foot upon landing on the upper level and increased trail limb swing time when negotiating the medium and high step height. Increased variability was also shown in a number of dependent measures. Data indicate that during step ascent, patients with CFL exhibit a cautious stepping strategy when compared to visual normal participants. This cautious strategy becomes increasingly evident when negotiating higher step heights, as shown by an increased planning time prior to entering the relatively unstable period of single support during the step up. The increased variability among CFL patients increases their likelihood of experiencing dynamic instability and falling during step ascent.

  19. A Mutational Hotspot and Strong Selection Contribute to the Order of Mutations Selected for during Escherichia coli Adaptation to the Gut

    PubMed Central

    Lourenço, Marta; Güleresi, Daniela; Barroso-Batista, João; Gordo, Isabel

    2016-01-01

    The relative role of drift versus selection underlying the evolution of bacterial species within the gut microbiota remains poorly understood. The large sizes of bacterial populations in this environment suggest that even adaptive mutations with weak effects, thought to be the most frequently occurring, could substantially contribute to a rapid pace of evolutionary change in the gut. We followed the emergence of intra-species diversity in a commensal Escherichia coli strain that previously acquired an adaptive mutation with strong effect during one week of colonization of the mouse gut. Following this first step, which consisted of inactivating a metabolic operon, one third of the subsequent adaptive mutations were found to have a selective effect as high as the first. Nevertheless, the order of the adaptive steps was strongly affected by a mutational hotspot with an exceptionally high mutation rate of 10−5. The pattern of polymorphism emerging in the populations evolving within different hosts was characterized by periodic selection, which reduced diversity, but also frequency-dependent selection, actively maintaining genetic diversity. Furthermore, the continuous emergence of similar phenotypes due to distinct mutations, known as clonal interference, was pervasive. Evolutionary change within the gut is therefore highly repeatable within and across hosts, with adaptive mutations of selection coefficients as strong as 12% accumulating without strong constraints on genetic background. In vivo competitive assays showed that one of the second steps (focA) exhibited positive epistasis with the first, while another (dcuB) exhibited negative epistasis. The data shows that strong effect adaptive mutations continuously recur in gut commensal bacterial species. PMID:27812114

  20. Outward Bound to the Galaxies--One Step at a Time

    ERIC Educational Resources Information Center

    Ward, R. Bruce; Miller-Friedmann, Jaimie; Sienkiewicz, Frank; Antonucci, Paul

    2012-01-01

    Less than a century ago, astronomers began to unlock the cosmic distances within and beyond the Milky Way. Understanding the size and scale of the universe is a continuing, step-by-step process that began with the remarkably accurate measurement of the distance to the Moon made by early Greeks. In part, the authors have ITEAMS (Innovative…

  1. Expressing Adaptation Strategies Using Adaptation Patterns

    ERIC Educational Resources Information Center

    Zemirline, N.; Bourda, Y.; Reynaud, C.

    2012-01-01

    Today, there is a real challenge to enable personalized access to information. Several systems have been proposed to address this challenge including Adaptive Hypermedia Systems (AHSs). However, the specification of adaptation strategies remains a difficult task for creators of such systems. In this paper, we consider the problem of the definition…

  2. Effects of dopaminergic therapy on locomotor adaptation and adaptive learning in persons with Parkinson's disease.

    PubMed

    Roemmich, Ryan T; Hack, Nawaz; Akbar, Umer; Hass, Chris J

    2014-07-15

    Persons with Parkinson's disease (PD) are characterized by multifactorial gait deficits, though the factors which influence the abilities of persons with PD to adapt and store new gait patterns are unclear. The purpose of this study was to investigate the effects of dopaminergic therapy on the abilities of persons with PD to adapt and store gait parameters during split-belt treadmill (SBT) walking. Ten participants with idiopathic PD who were being treated with stable doses of orally-administered dopaminergic therapy participated. All participants performed two randomized testing sessions on separate days: once while optimally-medicated (ON meds) and once after 12-h withdrawal from dopaminergic medication (OFF meds). During each session, locomotor adaptation was investigated as the participants walked on a SBT for 10 min while the belts moved at a 2:1 speed ratio. We assessed locomotor adaptive learning by quantifying: (1) aftereffects during de-adaptation (once the belts returned to tied speeds immediately following SBT walking) and (2) savings during re-adaptation (as the participants repeated the same SBT walking task after washout of aftereffects following the initial SBT task). The withholding of dopaminergic medication diminished step length aftereffects significantly during de-adaptation. However, both locomotor adaptation and savings were unaffected by levodopa. These findings suggest that dopaminergic pathways influence aftereffect storage but do not influence locomotor adaptation or savings within a single session of SBT walking. It appears important that persons with PD should be optimally-medicated if walking on the SBT as gait rehabilitation.

  3. Adapting natural resource management to climate change: The South Central Oregon and Northern Rockies Adaptation Partnerships

    NASA Astrophysics Data System (ADS)

    Halofsky, J.; Peterson, D. L.

    2015-12-01

    Concrete ways to adapt to climate change are needed to help natural resource managers take the first steps to incorporate climate change into management and take advantage of opportunities to balance the negative effects of climate change. We recently initiated two science-management climate change adaptation partnerships, one with three national forests and one national park in south central Oregon, and the other with 16 national forests, three national parks and other stakeholders in the northern Rockies region. Goals of both partnerships were to: (1) synthesize published information and data to assess the exposure, sensitivity, and adaptive capacity of key resource areas, including water use, infrastructure, fisheries, and vegetation and disturbance; (2) develop science-based adaptation strategies and tactics that will help to mitigate the negative effects of climate change and assist the transition of biological systems and management to a warmer climate; (3) ensure adaptation strategies and tactics are incorporated into relevant planning documents; and (4) foster an enduring partnership to facilitate ongoing dialogue and activities related to climate change in the partnerships regions. After an initial vulnerability assessment by agency and university scientists and local resource specialists, adaptation strategies and tactics were developed in a series of scientist-manager workshops. The final vulnerability assessments and adaptation actions are incorporated in technical reports. The partnerships produced concrete adaptation options for national forest and other natural resource managers and illustrated the utility of place-based vulnerability assessments and scientist-manager workshops in adapting to climate change.

  4. Adapting Natural Resource Management to Climate Change: The Blue Mountains and Northern Rockies Adaptation Partnerships

    NASA Astrophysics Data System (ADS)

    Halofsky, J.; Peterson, D. L.

    2014-12-01

    Concrete ways to adapt to climate change are needed to help natural resource managers take the first steps to incorporate climate change into management and take advantage of opportunities to balance the negative effects of climate change. We recently initiated two science-management climate change adaptation partnerships, one with three national forests and other key stakeholders in the Blue Mountains region of northeastern Oregon, and the other with 16 national forests, three national parks and other stakeholders in the northern Rockies region. Goals of both partnerships were to: (1) synthesize published information and data to assess the exposure, sensitivity, and adaptive capacity of key resource areas, including water use, infrastructure, fisheries, and vegetation and disturbance; (2) develop science-based adaptation strategies and tactics that will help to mitigate the negative effects of climate change and assist the transition of biological systems and management to a warmer climate; (3) ensure adaptation strategies and tactics are incorporated into relevant planning documents; and (4) foster an enduring partnership to facilitate ongoing dialogue and activities related to climate change in the partnerships regions. After an initial vulnerability assessment by agency and university scientists and local resource specialists, adaptation strategies and tactics were developed in a series of scientist-manager workshops. The final vulnerability assessments and adaptation actions are incorporated in technical reports. The partnerships produced concrete adaptation options for national forest and other natural resource managers and illustrated the utility of place-based vulnerability assessments and scientist-manager workshops in adapting to climate change.

  5. Variable Is Better Than Invariable: Sparse VSS-NLMS Algorithms with Application to Adaptive MIMO Channel Estimation

    PubMed Central

    Gui, Guan; Chen, Zhang-xin; Xu, Li; Wan, Qun; Huang, Jiyan; Adachi, Fumiyuki

    2014-01-01

    Channel estimation problem is one of the key technical issues in sparse frequency-selective fading multiple-input multiple-output (MIMO) communication systems using orthogonal frequency division multiplexing (OFDM) scheme. To estimate sparse MIMO channels, sparse invariable step-size normalized least mean square (ISS-NLMS) algorithms were applied to adaptive sparse channel estimation (ACSE). It is well known that step-size is a critical parameter which controls three aspects: algorithm stability, estimation performance, and computational cost. However, traditional methods are vulnerable to cause estimation performance loss because ISS cannot balance the three aspects simultaneously. In this paper, we propose two stable sparse variable step-size NLMS (VSS-NLMS) algorithms to improve the accuracy of MIMO channel estimators. First, ASCE is formulated in MIMO-OFDM systems. Second, different sparse penalties are introduced to VSS-NLMS algorithm for ASCE. In addition, difference between sparse ISS-NLMS algorithms and sparse VSS-NLMS ones is explained and their lower bounds are also derived. At last, to verify the effectiveness of the proposed algorithms for ASCE, several selected simulation results are shown to prove that the proposed sparse VSS-NLMS algorithms can achieve better estimation performance than the conventional methods via mean square error (MSE) and bit error rate (BER) metrics. PMID:25089286

  6. Advancements in adaptive aerodynamic technologies for airfoils and wings

    NASA Astrophysics Data System (ADS)

    Jepson, Jeffrey Keith

    Although aircraft operate over a wide range of flight conditions, current fixed-geometry aircraft are optimized for only a few of these conditions. By altering the shape of the aircraft, adaptive aerodynamics can be used to increase the safety and performance of an aircraft by tailoring the aircraft for multiple flight conditions. Of the various shape adaptation concepts currently being studied, the use of multiple trailing-edge flaps along the span of a wing offers a relatively high possibility of being incorporated on aircraft in the near future. Multiple trailing-edge flaps allow for effective spanwise camber adaptation with resulting drag benefits over a large speed range and load alleviation at high-g conditions. The research presented in this dissertation focuses on the development of this concept of using trailing-edge flaps to tailor an aircraft for multiple flight conditions. One of the major tasks involved in implementing trailing-edge flaps is in designing the airfoil to incorporate the flap. The first part of this dissertation presents a design formulation that incorporates aircraft performance considerations in the inverse design of low-speed laminar-flow adaptive airfoils with trailing-edge cruise flaps. The benefit of using adaptive airfoils is that the size of the low-drag region of the drag polar can be effectively increased without increasing the maximum thickness of the airfoil. Two aircraft performance parameters are considered: level-flight maximum speed and maximum range. It is shown that the lift coefficients for the lower and upper corners of the airfoil low-drag range can be appropriately adjusted to tailor the airfoil for these two aircraft performance parameters. The design problem is posed as a part of a multidimensional Newton iteration in an existing conformal-mapping based inverse design code, PROFOIL. This formulation automatically adjusts the lift coefficients for the corners of the low-drag range for a given flap deflection as

  7. [Biology of size and gravity].

    PubMed

    Yamashita, Masamichi; Baba, Shoji A

    2004-03-01

    responsible for this feature, are subject we discuss in this article. Three major topics in gravitational and space biology are; how living systems have been adapted to terrestrial gravity and evolved, how living systems respond to exotic gravitational environment, and whether living systems could respond and adapt to microgravity. Biology of size can contribute to find a way to answer these question, and answer why gravity is important in biology, at explaining why gravity has been a dominant factor through the evolutional history on the earth.

  8. Saccade adaptation specific to visual context.

    PubMed

    Herman, James P; Harwood, Mark R; Wallman, Josh

    2009-04-01

    When saccades consistently overshoot their targets, saccade amplitudes gradually decrease, thereby maintaining accuracy. This adaptive process has been seen as a form of motor learning that copes with changes in physical parameters of the eye and its muscles, brought about by aging or pathology. One would not expect such a motor-repair mechanism to be specific to the visual properties of the target stimulus. We had subjects make saccades to sudden movements of either of two targets-a steadily illuminated circle or a flickering circle-one of which stepped back during each saccade it elicited, simulating the effect of a hypermetric saccade. Saccade gain (saccade amplitude/target amplitude) decreased by 15% for the target that stepped back versus 6% for the target that did not step back. Most of the change in gain between successive blocks of trials of each type occurred on the first saccade of the block, decreasing by 0.12 on the first trial of a step-back block and increasing by 0.1 on the first trial of a no-step-back block. The differential adaptation of the two targets required postsaccadic feedback of both target types, as shown in a separate experiment, in which saccades to only one target received feedback, and the gain did not differ between the two target types. This demonstration that a context defined by a visual stimulus can serve as an effective cue for switching saccade gain between states suggests that saccade adaptation may have a heretofore unsuspected dimension of adaptability.

  9. Early steps of angiosperm pollinator coevolution.

    PubMed

    Hu, Shusheng; Dilcher, David L; Jarzen, David M; Winship Taylor, David

    2008-01-08

    The hypothesis that early flowering plants were insect-pollinated could be tested by an examination of the pollination biology of basal angiosperms and the pollination modes of fossil angiosperms. We provide data to show that early fossil angiosperms were insect-pollinated. Eighty-six percent of 29 extant basal angiosperm families have species that are zoophilous (of which 34% are specialized) and 17% of the families have species that are wind-pollinated, whereas basal eudicot families and basal monocot families more commonly have wind and specialized pollination modes (up to 78%). Character reconstruction based on recent molecular trees of angiosperms suggests that the most parsimonious result is that zoophily is the ancestral state. Combining pollen ornamentation, size, and aperture characteristics and the abundance of single-species pollen clumps of Cenomanian angiosperm-dispersed pollen species from the Dakota Formation demonstrates a dominance of zoophilous pollination (76% versus 24% wind pollination). The zoophilous pollen species have adaptations for pollination by generalist insects (39%), specialized pollen-collecting insects (27%), and other specialized pollinators (10%). These data quantify the presences of more specialized pollination modes during the mid-Cretaceous angiosperm diversification.

  10. Early steps of angiosperm–pollinator coevolution

    PubMed Central

    Hu, Shusheng; Dilcher, David L.; Jarzen, David M.; Winship Taylor, David

    2008-01-01

    The hypothesis that early flowering plants were insect-pollinated could be tested by an examination of the pollination biology of basal angiosperms and the pollination modes of fossil angiosperms. We provide data to show that early fossil angiosperms were insect-pollinated. Eighty-six percent of 29 extant basal angiosperm families have species that are zoophilous (of which 34% are specialized) and 17% of the families have species that are wind-pollinated, whereas basal eudicot families and basal monocot families more commonly have wind and specialized pollination modes (up to 78%). Character reconstruction based on recent molecular trees of angiosperms suggests that the most parsimonious result is that zoophily is the ancestral state. Combining pollen ornamentation, size, and aperture characteristics and the abundance of single-species pollen clumps of Cenomanian angiosperm-dispersed pollen species from the Dakota Formation demonstrates a dominance of zoophilous pollination (76% versus 24% wind pollination). The zoophilous pollen species have adaptations for pollination by generalist insects (39%), specialized pollen-collecting insects (27%), and other specialized pollinators (10%). These data quantify the presences of more specialized pollination modes during the mid-Cretaceous angiosperm diversification. PMID:18172206

  11. Cardiovascular Adaptations to Exercise Training.

    PubMed

    Hellsten, Ylva; Nyberg, Michael

    2015-12-15

    Aerobic exercise training leads to cardiovascular changes that markedly increase aerobic power and lead to improved endurance performance. The functionally most important adaptation is the improvement in maximal cardiac output which is the result of an enlargement in cardiac dimension, improved contractility, and an increase in blood volume, allowing for greater filling of the ventricles and a consequent larger stroke volume. In parallel with the greater maximal cardiac output, the perfusion capacity of the muscle is increased, permitting for greater oxygen delivery. To accommodate the higher aerobic demands and perfusion levels, arteries, arterioles, and capillaries adapt in structure and number. The diameters of the larger conduit and resistance arteries are increased minimizing resistance to flow as the cardiac output is distributed in the body and the wall thickness of the conduit and resistance arteries is reduced, a factor contributing to increased arterial compliance. Endurance training may also induce alterations in the vasodilator capacity, although such adaptations are more pronounced in individuals with reduced vascular function. The microvascular net increases in size within the muscle allowing for an improved capacity for oxygen extraction by the muscle through a greater area for diffusion, a shorter diffusion distance, and a longer mean transit time for the erythrocyte to pass through the smallest blood vessels. The present article addresses the effect of endurance training on systemic and peripheral cardiovascular adaptations with a focus on humans, but also covers animal data.

  12. LBTO's long march to full operation - step 1

    NASA Astrophysics Data System (ADS)

    Veillet, C.; Brynnel, J.; Hill, J.; Wagner, R.; Ashby, D.; Christou, J.; Little, J.; Summers, D.

    2014-08-01

    For the LBT Observatory, the next couple of years promise to be both exciting and challenging. Exciting as the long awaited suite of first generation instruments and GLAO become available for binocular operations, while regular interferometric observations will make LBT the first operational ELT. Challenging because LBTO will have to handle maintenance and upgrades of instruments or key components like its adaptive secondaries about which it has much to learn. Step1 will outline a plan optimizing LBTOs scientific production while mitigating the consequences of the inevitable setbacks the challenges will bring.

  13. Single-phase-field model of stepped surfaces.

    PubMed

    Castro, M; Hernández-Machado, A; Cuerno, R

    2009-02-01

    We formulate a phase-field description of step dynamics on vicinal surfaces that makes use of a single dynamical field, at variance with previous analogous works in which two coupled fields are employed, namely, a phase-field proper plus the physical adatom concentration. Within an asymptotic sharp interface limit, our formulation is shown to retrieve the standard Burton-Cabrera-Frank model in the general case of asymmetric attachment coefficients (Ehrlich-Schwoebel effect). We confirm our analytical results by means of numerical simulations of our phase-field model. Our present formulation seems particularly well adapted to generalization when additional physical fields are required.

  14. Safeguards Envelope: The First Steps

    SciTech Connect

    Richard Metcalf; Jean Ragusa; Robert Bean

    2008-03-01

    The possibility exists for real time accountancy and assay of nuclear materials as they move through a reprocessing facility. This project aims to establish working parameters and local figures of merit to identify possible diversion in real time with minimal operational impact. Factors such as pH, NOX gas concentration, flow speeds and radiation fields are rarely taken into account in safeguards methodologies and will be included to increase the confidence of location and assay of nuclear materials. An adaptable, real data model is being created of the contactors of the Advanced Fuel Cycle Facility and will be analyzed using the appropriate modeling codes. This model will then be subjected to three, diversion scenarios and a figure of merit methodology will be utilized to create the operational parameters under which these diversion scenarios would be detected. This analysis for figure of merit methodology will include statistical fluctuations, operator error, and a rudimentary analysis of transient conditions. The long term goal of the project includes expansion universally over the plant, methods of detection without requiring access to proprietary information, and an evaluation of the requirements for future figure of merit methodologies.

  15. Accurate and stable time stepping in ice sheet modeling

    NASA Astrophysics Data System (ADS)

    Cheng, Gong; Lötstedt, Per; von Sydow, Lina

    2017-01-01

    In this paper we introduce adaptive time step control for simulation of the evolution of ice sheets. The discretization error in the approximations is estimated using "Milne's device" by comparing the result from two different methods in a predictor-corrector pair. Using a predictor-corrector pair the expensive part of the procedure, the solution of the velocity and pressure equations, is performed only once per time step and an estimate of the local error is easily obtained. The stability of the numerical solution is maintained and the accuracy is controlled by keeping the local error below a given threshold using PI-control. Depending on the threshold, the time step Δt is bound by stability requirements or accuracy requirements. Our method takes a shorter Δt than an implicit method but with less work in each time step and the solver is simpler. The method is analyzed theoretically with respect to stability and applied to the simulation of a 2D ice slab and a 3D circular ice sheet. The stability bounds in the experiments are explained by and agree well with the theoretical results.

  16. A New Type of Motor: Pneumatic Step Motor

    PubMed Central

    Stoianovici, Dan; Patriciu, Alexandru; Petrisor, Doru; Mazilu, Dumitru; Kavoussi, Louis

    2011-01-01

    This paper presents a new type of pneumatic motor, a pneumatic step motor (PneuStep). Directional rotary motion of discrete displacement is achieved by sequentially pressurizing the three ports of the motor. Pulsed pressure waves are generated by a remote pneumatic distributor. The motor assembly includes a motor, gearhead, and incremental position encoder in a compact, central bore construction. A special electronic driver is used to control the new motor with electric stepper indexers and standard motion control cards. The motor accepts open-loop step operation as well as closed-loop control with position feedback from the enclosed sensor. A special control feature is implemented to adapt classic control algorithms to the new motor, and is experimentally validated. The speed performance of the motor degrades with the length of the pneumatic hoses between the distributor and motor. Experimental results are presented to reveal this behavior and set the expectation level. Nevertheless, the stepper achieves easily controllable precise motion unlike other pneumatic motors. The motor was designed to be compatible with magnetic resonance medical imaging equipment, for actuating an image-guided intervention robot, for medical applications. For this reason, the motors were entirely made of nonmagnetic and dielectric materials such as plastics, ceramics, and rubbers. Encoding was performed with fiber optics, so that the motors are electricity free, exclusively using pressure and light. PneuStep is readily applicable to other pneumatic or hydraulic precision-motion applications. PMID:21528106

  17. Split-Step Timing of Professional and Junior Tennis Players

    PubMed Central

    Leskosek, Bojan; Filipcic, Tjasa

    2017-01-01

    Abstract The purpose of the study was to determine the timing of a split-step in three categories of tennis players in four groups of strokes. Subjects were divided into three groups: male and female junior, and male professional tennis players. During two tournaments, all matches were recorded with two fixed video cameras. For every stroke, the timing of the split-step between the opponent’s impact point when hitting the ball and the player’s split-step was measured. A two-way analysis of variance (ANOVA) was used to determine the differences between groups of strokes, players and the interaction Player x Stroke Group. A Tukey post-hoc test was employed to determine specific differences. The results revealed differences between players in detecting the opponent’s movement, stroke and ball flight, which were reflected in different split-step timings. Each tennis player has his/her own timing mechanism which they adapt to various game situations. Response times differ significantly depending on the game situation. On average, they are the lowest in the serve, and then gradually rise from the return of the serve to baseline game, reaching the highest values in specific game situations. Players react faster in the first serve than in the second one and in the return of the serve, the response times are lower after the return of the second serve PMID:28210342

  18. Adaptive control based on retrospective cost optimization

    NASA Astrophysics Data System (ADS)

    Santillo, Mario A.

    This dissertation studies adaptive control of multi-input, multi-output, linear, time-invariant, discrete-time systems that are possibly unstable and nonminimum phase. We consider both gradient-based adaptive control as well as retrospective-cost-based adaptive control. Retrospective cost optimization is a measure of performance at the current time based on a past window of data and without assumptions about the command or disturbance signals. In particular, retrospective cost optimization acts as an inner loop to the adaptive control algorithm by modifying the performance variables based on the difference between the actual past control inputs and the recomputed past control inputs based on the current control law. We develop adaptive control algorithms that are effective for systems that are nonminimum phase. We consider discrete-time adaptive control since these control laws can be implemented directly in embedded code without requiring an intermediate discretization step. Furthermore, the adaptive controllers in this dissertation are developed under minimal modeling assumptions. In particular, the adaptive controllers require knowledge of the sign of the high-frequency gain and a sufficient number of Markov parameters to approximate the nonminimum-phase zeros (if any). No additional modeling information is necessary. The adaptive controllers presented in this dissertation are developed for full-state-feedback stabilization, static-output-feedback stabilization, as well as dynamic compensation for stabilization, command following, disturbance rejection, and model reference adaptive control. Lyapunov-based stability and convergence proofs are provided for special cases. We present numerical examples to illustrate the algorithms' effectiveness in handling systems that are unstable and/or nonminimum phase and to provide insight into the modeling information required for controller implementation.

  19. Roadmap towards justice in urban climate adaptation research

    NASA Astrophysics Data System (ADS)

    Shi, Linda; Chu, Eric; Anguelovski, Isabelle; Aylett, Alexander; Debats, Jessica; Goh, Kian; Schenk, Todd; Seto, Karen C.; Dodman, David; Roberts, Debra; Roberts, J. Timmons; Vandeveer, Stacy D.

    2016-02-01

    The 2015 United Nations Climate Change Conference in Paris (COP21) highlighted the importance of cities to climate action, as well as the unjust burdens borne by the world's most disadvantaged peoples in addressing climate impacts. Few studies have documented the barriers to redressing the drivers of social vulnerability as part of urban local climate change adaptation efforts, or evaluated how emerging adaptation plans impact marginalized groups. Here, we present a roadmap to reorient research on the social dimensions of urban climate adaptation around four issues of equity and justice: (1) broadening participation in adaptation planning; (2) expanding adaptation to rapidly growing cities and those with low financial or institutional capacity; (3) adopting a multilevel and multi-scalar approach to adaptation planning; and (4) integrating justice into infrastructure and urban design processes. Responding to these empirical and theoretical research needs is the first step towards identifying pathways to more transformative adaptation policies.

  20. Strategy Guideline: HVAC Equipment Sizing

    SciTech Connect

    Burdick, A.

    2012-02-01

    The heating, ventilation, and air conditioning (HVAC) system is arguably the most complex system installed in a house and is a substantial component of the total house energy use. A right-sized HVAC system will provide the desired occupant comfort and will run efficiently. This Strategy Guideline discusses the information needed to initially select the equipment for a properly designed HVAC system. Right-sizing of an HVAC system involves the selection of equipment and the design of the air distribution system to meet the accurate predicted heating and cooling loads of the house. Right-sizing the HVAC system begins with an accurate understanding of the heating and cooling loads on a space; however, a full HVAC design involves more than just the load estimate calculation - the load calculation is the first step of the iterative HVAC design procedure. This guide describes the equipment selection of a split system air conditioner and furnace for an example house in Chicago, IL as well as a heat pump system for an example house in Orlando, Florida. The required heating and cooling load information for the two example houses was developed in the Department of Energy Building America Strategy Guideline: Accurate Heating and Cooling Load Calculations.

  1. Biofunctional Understanding and Judgment of Size

    PubMed Central

    Jin, Zheng; Lee, Yang; Yuan, Zheng

    2016-01-01

    Research has shown that the meaningfulness of the material increases judged size, whereas symmetry decreases size judgments. These findings have been interpreted in terms of information processing, with a greater quantity of information leading to a judgment of larger size. An alternative view based on biofunctional understanding theory emphasizes the quality of affordance-triggered biological activity as reported and observed in attitudes toward playing sports, effortless understanding, knowledge-in-action, meditative wisdom, and body–mind cycle of adaptation. This alternative implies that affordance biofunctional activity is naturally size-diminishinging as it moves toward coherence and size-expanding as it moves away from coherence influencing judgments of size accordingly. Here we tested this hypothesis in the realm of sensorimotor integration. Our first experiment showed that phonologically unpronounced or symmetric symbols elicit smaller size judgments than phonologically pronounced and asymmetric symbols. Next, we manipulated the quantity of meaning with the affordance (possibilities for biofunctional activity) orthogonally in a second experiment; results indicated that meaning affects size judgments only in the absence of phonological information. We conclude that the biofunctional activity affordance may be responsible for observed differences in size judgment. PMID:27047438

  2. Passive adaptive imaging through turbulence

    NASA Astrophysics Data System (ADS)

    Tofsted, David

    2016-05-01

    Standard methods for improved imaging system performance under degrading optical turbulence conditions typically involve active adaptive techniques or post-capture image processing. Here, passive adaptive methods are considered where active sources are disallowed, a priori. Theoretical analyses of short-exposure turbulence impacts indicate that varying aperture sizes experience different degrees of turbulence impacts. Smaller apertures often outperform larger aperture systems as turbulence strength increases. This suggests a controllable aperture system is advantageous. In addition, sub-aperture sampling of a set of training images permits the system to sense tilts in different sub-aperture regions through image acquisition and image cross-correlation calculations. A four sub-aperture pattern supports corrections involving five realizable operating modes (beyond tip and tilt) for removing aberrations over an annular pattern. Progress to date will be discussed regarding development and field trials of a prototype system.

  3. Simulation of Unique Pressure Changing Steps and Situations in Psa Processes

    NASA Technical Reports Server (NTRS)

    Ebner, Armin D.; Mehrotra, Amal; Knox, James C.; LeVan, Douglas; Ritter, James A.

    2007-01-01

    A more rigorous cyclic adsorption process simulator is being developed for use in the development and understanding of new and existing PSA processes. Unique features of this new version of the simulator that Ritter and co-workers have been developing for the past decade or so include: multiple absorbent layers in each bed, pressure drop in the column, valves for entering and exiting flows and predicting real-time pressurization and depressurization rates, ability to account for choked flow conditions, ability to pressurize and depressurize simultaneously from both ends of the columns, ability to equalize between multiple pairs of columns, ability to equalize simultaneously from both ends of pairs of columns, and ability to handle very large pressure ratios and hence velocities associated with deep vacuum systems. These changes to the simulator now provide for unique opportunities to study the effects of novel pressure changing steps and extreme process conditions on the performance of virtually any commercial or developmental PSA process. This presentation will provide an overview of the cyclic adsorption process simulator equations and algorithms used in the new adaptation. It will focus primarily on the novel pressure changing steps and their effects on the performance of a PSA system that epitomizes the extremes of PSA process design and operation. This PSA process is a sorbent-based atmosphere revitalization (SBAR) system that NASA is developing for new manned exploration vehicles. This SBAR system consists of a 2-bed 3-step 3-layer system that operates between atmospheric pressure and the vacuum of space, evacuates from both ends of the column simultaneously, experiences choked flow conditions during pressure changing steps, and experiences a continuously changing feed composition, as it removes metabolic CO2 and H20 from a closed and fixed volume, i.e., the spacecraft cabin. Important process performance indicators of this SBAR system are size, and the

  4. Extracorporeal gas exchange in acute lung injury: step by step towards expanded indications?

    PubMed Central

    2010-01-01

    Extracorporeal membrane oxygenation (ECMO) is widely accepted as a rescue therapy in patients with acute life-threatening hypoxemia in the course of severe acute respiratory distress syndrome (ARDS). However, possible side effects and complications are considered to limit beneficial outcome effects. Therefore, widening indications with the aim of reducing ventilator induced lung injury (VILI) is still controversial. Consequently, technological progress is an important strategy. Miniaturized ECMO systems are believed to simplify handling and reduce side effects and complications. Mueller and co-workers evaluated such a small-sized device in 60 patients with severe ARDS. They accomplished both the treatment of severe hypoxemia and reduction of VILI, demonstrating feasibility, a moderate rate of severe complications, and a 45% intensive care survival rate. Although neither randomized nor controlled, this study should encourage others to implement such systems in clinical practice. From a strategic perspective, this is another small but useful step towards implementing extracorporeal gas exchange for the prevention of VILI. It is already common sense that the prevention of acute life-threatening hypoxemia usually outweighs the risks of this technique. The next step should be to prove that prevention of life-threatening VILI balances the risks too. PMID:20236482

  5. Extracorporeal gas exchange in acute lung injury: step by step towards expanded indications?

    PubMed

    Dembinski, Rolf; Kuhlen, Ralf

    2010-01-01

    Extracorporeal membrane oxygenation (ECMO) is widely accepted as a rescue therapy in patients with acute life-threatening hypoxemia in the course of severe acute respiratory distress syndrome (ARDS). However, possible side effects and complications are considered to limit beneficial outcome effects. Therefore, widening indications with the aim of reducing ventilator induced lung injury (VILI) is still controversial. Consequently, technological progress is an important strategy. Miniaturized ECMO systems are believed to simplify handling and reduce side effects and complications. Mueller and co-workers evaluated such a small-sized device in 60 patients with severe ARDS. They accomplished both the treatment of severe hypoxemia and reduction of VILI, demonstrating feasibility, a moderate rate of severe complications, and a 45% intensive care survival rate. Although neither randomized nor controlled, this study should encourage others to implement such systems in clinical practice. From a strategic perspective, this is another small but useful step towards implementing extracorporeal gas exchange for the prevention of VILI. It is already common sense that the prevention of acute life-threatening hypoxemia usually outweighs the risks of this technique. The next step should be to prove that prevention of life-threatening VILI balances the risks too.

  6. Adaptive radiation of multituberculate mammals before the extinction of dinosaurs.

    PubMed

    Wilson, Gregory P; Evans, Alistair R; Corfe, Ian J; Smits, Peter D; Fortelius, Mikael; Jernvall, Jukka

    2012-03-14

    The Cretaceous-Paleogene mass extinction approximately 66 million years ago is conventionally thought to have been a turning point in mammalian evolution. Prior to that event and for the first two-thirds of their evolutionary history, mammals were mostly confined to roles as generalized, small-bodied, nocturnal insectivores, presumably under selection pressures from dinosaurs. Release from these pressures, by extinction of non-avian dinosaurs at the Cretaceous-Paleogene boundary, triggered ecological diversification of mammals. Although recent individual fossil discoveries have shown that some mammalian lineages diversified ecologically during the Mesozoic era, comprehensive ecological analyses of mammalian groups crossing the Cretaceous-Paleogene boundary are lacking. Such analyses are needed because diversification analyses of living taxa allow only indirect inferences of past ecosystems. Here we show that in arguably the most evolutionarily successful clade of Mesozoic mammals, the Multituberculata, an adaptive radiation began at least 20 million years before the extinction of non-avian dinosaurs and continued across the Cretaceous-Paleogene boundary. Disparity in dental complexity, which relates to the range of diets, rose sharply in step with generic richness and disparity in body size. Moreover, maximum dental complexity and body size demonstrate an adaptive shift towards increased herbivory. This dietary expansion tracked the ecological rise of angiosperms and suggests that the resources that were available to multituberculates were relatively unaffected by the Cretaceous-Paleogene mass extinction. Taken together, our results indicate that mammals were able to take advantage of new ecological opportunities in the Mesozoic and that at least some of these opportunities persisted through the Cretaceous-Paleogene mass extinction. Similar broad-scale ecomorphological inventories of other radiations may help to constrain the possible causes of mass extinctions.

  7. Stepping Up to Science and Math

    ERIC Educational Resources Information Center

    Goldston, Dee

    2004-01-01

    "Stepping Up to Science and Math" invites teachers to step back and rethink the way they teach both of these essential subjects. Then it illustrates how teachers can step up the pace with Standards-based activities that make learning more effective and efficient. (New lessons featuring gummy worms, school buses, or the planet Mars help teachers…

  8. STEPS: Moving from Welfare to Work.

    ERIC Educational Resources Information Center

    Vail, Ann; Cummings, Merrilyn; Kratzer, Connie; Galindo, Vickie

    Cooperative extension service faculty at New Mexico State University started the Steps to Employment and Personal Success (STEPS) program to help Temporary Assistance for Needy Families (TANF) clients qualify for and maintain full-time employment and strengthen their families for long-term success. Clients are referred to STEPS by New Mexico…

  9. CAD for 4-step braided fabric composites

    SciTech Connect

    Pandey, R.; Hahn, H.T.

    1994-12-31

    A general framework is provided to predict thermoelastic properties of three dimensional 4-step braided fabric composites. Three key steps involved are (1) the development of a CAD model for yarn architecture, (2) the extraction of a unit cell (3) the prediction of the thermoelastic properties based on micromechanics. Main features of each step are summarized and experimental correlations are provided in the paper.

  10. 7 CFR 60.122 - Production step.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Production step. 60.122 Section 60.122 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... FOR FISH AND SHELLFISH General Provisions Definitions § 60.122 Production step. Production step...

  11. 7 CFR 65.230 - Production step.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Production step. 65.230 Section 65.230 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards..., PEANUTS, AND GINSENG General Provisions Definitions § 65.230 Production step. Production step means,...

  12. 7 CFR 65.230 - Production step.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Production step. 65.230 Section 65.230 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards..., PEANUTS, AND GINSENG General Provisions Definitions § 65.230 Production step. Production step means,...

  13. The Complexity of One-Step Equations

    ERIC Educational Resources Information Center

    Ngu, Bing

    2014-01-01

    An analysis of one-step equations from a cognitive load theory perspective uncovers variation within one-step equations. The complexity of one-step equations arises from the element interactivity across the operational and relational lines. The higher the number of operational and relational lines, the greater the complexity of the equations.…

  14. Ten steps to successful software process improvement

    NASA Technical Reports Server (NTRS)

    Kandt, R. K.

    2003-01-01

    This paper identifies ten steps for managing change that address organizational and cultural issues. Four of these steps are critical, that if not done, will almost guarantee failure. This ten-step program emphasizes the alignment of business goals, change process goals, and the work performed by the employees of an organization.

  15. 15 CFR 732.1 - Steps overview.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INDUSTRY AND SECURITY, DEPARTMENT OF COMMERCE EXPORT ADMINISTRATION REGULATIONS STEPS FOR USING THE EAR § 732.1 Steps overview. (a)(1) Introduction. In this part, references to the EAR are references to 15... EAR by listing logical steps in § 732.2 through § 732.5 of this part that you can take in...

  16. 15 CFR 732.1 - Steps overview.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INDUSTRY AND SECURITY, DEPARTMENT OF COMMERCE EXPORT ADMINISTRATION REGULATIONS STEPS FOR USING THE EAR § 732.1 Steps overview. (a)(1) Introduction. In this part, references to the EAR are references to 15... EAR by listing logical steps in § 732.2 through § 732.5 of this part that you can take in...

  17. 15 CFR 732.1 - Steps overview.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INDUSTRY AND SECURITY, DEPARTMENT OF COMMERCE EXPORT ADMINISTRATION REGULATIONS STEPS FOR USING THE EAR § 732.1 Steps overview. (a)(1) Introduction. In this part, references to the EAR are references to 15... EAR by listing logical steps in § 732.2 through § 732.5 of this part that you can take in...

  18. 15 CFR 732.1 - Steps overview.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INDUSTRY AND SECURITY, DEPARTMENT OF COMMERCE EXPORT ADMINISTRATION REGULATIONS STEPS FOR USING THE EAR § 732.1 Steps overview. (a)(1) Introduction. In this part, references to the EAR are references to 15... EAR by listing logical steps in § 732.2 through § 732.5 of this part that you can take in...

  19. 15 CFR 732.1 - Steps overview.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... INDUSTRY AND SECURITY, DEPARTMENT OF COMMERCE EXPORT ADMINISTRATION REGULATIONS STEPS FOR USING THE EAR § 732.1 Steps overview. (a)(1) Introduction. In this part, references to the EAR are references to 15... EAR by listing logical steps in § 732.2 through § 732.5 of this part that you can take in...

  20. Mixing and Matching Deep-UV Step-and-Scan with I-Line Step and Repeat

    NASA Astrophysics Data System (ADS)

    Sewell, Harry

    1995-12-01

    This paper reviews all the major aspects of successfully implementing a “mix and match” (Deep-UV/I-line, stepper/scanner) strategy. The resolution and linewidth-control limits of I-line are quantified for a number of the process levels and compared with the capabilities of Deep-UV step-and-scan. This analysis predicts the typical mix of steppers and scanners in a 256 MBit production line for 250 nm lithography. A step-by-step procedure to achieve and monitor successful matching is reviewed. The procedure begins by defining a “golden system”, which is used to produce reference wafers for the setup and monitoring of all the systems being mixed and matched. The reference wafers are used to ensure that the pre-aligners of the systems are calibrated and that offsets are adapted to allow the transfer of wafers between systems. The wafers are also used to match both wafer-stage grid and exposure-field distortions. The matching of both wafer-grid and stepper-field distortions are reviewed. The implementation of stage correction-tables is demonstrated. It is indicated that grid matching to better than 10 nm is achievable. It is also indicated that the dynamic scanning of a step-and-scan system allows the monitoring and correction of such typical stepper problems as field magnification and rotation. The critical aspects of multi-field matching between stepper and scanner are analyzed. The key factors that allow the successful overlaying of large, single, scanned fields with multiple, small, stepped fields are reviewed. The total overlay accuracy achieved using step-and-scan, and “mix-and-match” is analyzed and demonstrated.