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Sample records for sun-earth l2 point

  1. Orbit Determination Error Analysis Results for the Triana Sun-Earth L2 Libration Point Mission

    Science.gov (United States)

    Marr, G.

    2003-01-01

    Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination error analysis results are presented for all phases of the Triana Sun-Earth L1 libration point mission and for the science data collection phase of a future Sun-Earth L2 libration point mission. The Triana spacecraft was nominally to be released by the Space Shuttle in a low Earth orbit, and this analysis focuses on that scenario. From the release orbit a transfer trajectory insertion (TTI) maneuver performed using a solid stage would increase the velocity be approximately 3.1 km/sec sending Triana on a direct trajectory to its mission orbit. The Triana mission orbit is a Sun-Earth L1 Lissajous orbit with a Sun-Earth-vehicle (SEV) angle between 4.0 and 15.0 degrees, which would be achieved after a Lissajous orbit insertion (LOI) maneuver at approximately launch plus 6 months. Because Triana was to be launched by the Space Shuttle, TTI could potentially occur over a 16 orbit range from low Earth orbit. This analysis was performed assuming TTI was performed from a low Earth orbit with an inclination of 28.5 degrees and assuming support from a combination of three Deep Space Network (DSN) stations, Goldstone, Canberra, and Madrid and four commercial Universal Space Network (USN) stations, Alaska, Hawaii, Perth, and Santiago. These ground stations would provide coherent two-way range and range rate tracking data usable for orbit determination. Larger range and range rate errors were assumed for the USN stations. Nominally, DSN support would end at TTI+144 hours assuming there were no USN problems. Post-TTI coverage for a range of TTI longitudes for a given nominal trajectory case were analyzed. The orbit determination error analysis after the first correction maneuver would be generally applicable to any libration point mission utilizing a direct trajectory.

  2. Minimum time solar sailing from geosynchronous orbit to the sun-earth L2 point

    Science.gov (United States)

    Hur, Sun H.; Bryson, Arthur E., Jr.

    1992-08-01

    An approximate time-optimal of a solar sail from a geosynchronous orbit to the sun-earth L2 libration point is found using a combined method of local optimization and single shooting. The local optimization strategy is based on maximizing the time rate of change of an energy variable at each time. This strategy overcomes the numerical difficulties associated with solving optimal control problems of long duration like the solar sail transfer problem. The single shooting portion of the method is employed to meet the terminal constraints. The combined method can be applied to other optimal low thrust transfer problems of long duration.

  3. Formation Flying Satellite Control Around the L2 Sun-Earth Libration Point

    Science.gov (United States)

    Hamilton, Nicholas H.

    2001-12-01

    A growing interest in formation flying satellites demands development and analysis of control and estimation algorithms for station-keeping and formation maneuvering. This thesis discusses the development of a discrete linear-quadratic- regulator control algorithm for formations in the vicinity of the L2 sun-earth libration point. The development of an appropriate Kalman filter is included as well. Simulations are created for the analysis of the station-keeping and various formation maneuvers of the Stellar Imager mission. The simulations provide tracking error, estimation error, and control effort results. From the control effort, useful design parameters such as AV and propellant mass are determined. For formation maneuvering, the drone spacecraft track to within 4 meters of their desired position and within 1.3 millimeters per second of their desired zero velocity. The filter, with few exceptions, keeps the estimation errors within their three-sigma values. Without noise, the controller performs extremely well, with the drones tracking to within several micrometers. Bach drone uses around 1 to 2 grams of propellant per maneuver, depending on the circumstances.

  4. Orbit Determination (OD) Error Analysis Results for the Triana Sun-Earth L1 Libration Point Mission and for the Fourier Kelvin Stellar Interferometer (FKSI) Sun-Earth L2 Libration Point Mission Concept

    Science.gov (United States)

    Marr, Greg C.

    2003-01-01

    The Triana spacecraft was designed to be launched by the Space Shuttle. The nominal Triana mission orbit will be a Sun-Earth L1 libration point orbit. Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination (OD) error analysis results are presented for all phases of the Triana mission from the first correction maneuver through approximately launch plus 6 months. Results are also presented for the science data collection phase of the Fourier Kelvin Stellar Interferometer Sun-Earth L2 libration point mission concept with momentum unloading thrust perturbations during the tracking arc. The Triana analysis includes extensive analysis of an initial short arc orbit determination solution and results using both Deep Space Network (DSN) and commercial Universal Space Network (USN) statistics. These results could be utilized in support of future Sun-Earth libration point missions.

  5. CHANG'E-2 lunar escape maneuvers to the Sun-Earth L2 libration point mission

    Science.gov (United States)

    Liu, Lei; Liu, Yong; Cao, Jianfeng; Hu, Songjie; Tang, Geshi; Xie, Jianfeng

    2014-01-01

    This paper addresses lunar escape maneuvers of the first Chinese Sun-Earth L2 libration point mission by the CHANG'E-2 satellite, which is also the world's first satellite to reach the L2 point from a lunar orbit. The lunar escape maneuvers are heavily constrained by the remaining propellant and the condition of telemetry, track and command, among others. First, these constraints are analyzed and summarized to design a target L2 Lissajous orbit and an initial transfer trajectory. Second, the maneuver mathematical models are studied. The multilevel maneuver schemes which consist of phasing maneuvers and a final lunar escape maneuver are designed for actual operations. Based on the scheme analysis and comparison, the 2-maneuver scheme with a 5.3-h-period phasing orbit is ultimately selected. Finally, the mission status based on the scheme is presented and the control operation results are discussed in detail. The methodology in this paper is especially beneficial and applicable to a future multi-mission instance in the deep space exploration.

  6. Spacecraft Formation Flying near Sun-Earth L2 Lagrange Point: Trajectory Generation and Adaptive Full-State Feedback Control

    Science.gov (United States)

    Wong, Hong; Kapila, Vikram

    2004-01-01

    In this paper, we present a method for trajectory generation and adaptive full-state feedback control to facilitate spacecraft formation flying near the Sun-Earth L2 Lagrange point. Specifically, the dynamics of a spacecraft in the neighborhood of a Halo orbit reveals that there exist quasi-periodic orbits surrounding the Halo orbit. Thus, a spacecraft formation is created by placing a leader spacecraft on a desired Halo orbit and placing follower spacecraft on desired quasi-periodic orbits. To produce a formation maintenance controller, we first develop the nonlinear dynamics of a follower spacecraft relative to the leader spacecraft. We assume that the leader spacecraft is on a desired Halo orbit trajectory and the follower spacecraft is to track a desired quasi-periodic orbit surrounding the Halo orbit. Then, we design an adaptive, full-state feedback position tracking controller for the follower spacecraft providing an adaptive compensation for the unknown mass of the follower spacecraft. The proposed control law is simulated for the case of the leader and follower spacecraft pair and is shown to yield global, asymptotic convergence of the relative position tracking errors.

  7. Capturing small asteroids into a Sun-Earth Lagrangian point

    Science.gov (United States)

    Lladó, Neus; Ren, Yuan; Masdemont, Josep J.; Gómez, Gerard

    2014-02-01

    In this paper we address the feasibility of capturing small Near-Earth Asteroids (NEAs) into the vicinity of the Sun-Earth L2 libration point using a continuous-thrust propulsion system assumed to be attached to the asteroid. The vicinity of this libration point is a gateway to the Earth-Moon neighborhood and using it for capture, or for transit, small NEAs could be interesting for mining or science purposes.

  8. Capturing small asteroids into Sun-Earth Lagrangian points for mining purposes

    OpenAIRE

    Lladó, Neus; Ren, Yuan; Masdemont Soler, Josep; Gomez Muntaner, Gerard

    2012-01-01

    The aim of this paper is to study the capture of small Near Earth Objects (NEOs) into the Sun-Earth L2 using low-thrust propulsion for mining or science purposes. As it is well known, the vicinity of these points is inside a net of dynamical channels suitable for the transport in the Earth-Moon neighborhood, so different final destinations from here could be easily considered. Asteroids with very small mass and not representing a potential hazard are analyzed. An initial pruning o...

  9. Solar radiation pressure used for formation flying control around the Sun-Earth libration point

    Institute of Scientific and Technical Information of China (English)

    Sheng-ping GONG; Jun-feng LI; He-xi BAOYIN

    2009-01-01

    Solar radiation pressure is used to control the formation flying around the L2 libration point in the Sun-Earth system. Formation flying control around a halo orbit requires a very small thrust that cannot be satisfied by the latest thrusters. The key contribution of this paper is that the continuous low thrust is produced by solar radiation pressure to achieve the tight formation flying around the libration point. However, only certain families of formation types can be controlled by solar radiation pressure since the direction of solar radiation pressure is restricted to a certain range. Two types of feasible formations using solar radiation pressure control are designed. The conditions of feasible formations are given analytically. Simulations are presented for each case, and the results show that the formations are well controlled by solar radiation pressure.

  10. Understanding the Sun-Earth Libration Point Orbit Formation Flying Challenges For WFIRST and Starshade

    Science.gov (United States)

    Webster, Cassandra M.; Folta, David C.

    2017-01-01

    In order to fly an occulter in formation with a telescope at the Sun-Earth L2 (SEL2) Libration Point, one must have a detailed understanding of the dy-namics that govern the restricted three body system. For initial purposes, a linear approximation is satisfactory, but operations will require a high-fidelity modeling tool along with strategic targeting methods in order to be successful. This paper focuses on the challenging dynamics of the transfer trajectories to achieve the relative positioning of two spacecraft to fly in formation at SEL2, in our case, the Wide-Field Infrared Survey Telescope (WFIRST) and a proposed Starshade. By modeling the formation transfers using a high fidelity tool, an accurate V approximation can be made to as-sist with the development of the subsystem design required for a WFIRST and Starshade formation flight mission.

  11. Long Term Missions at the Sun-Earth Libration Point L1: ACE, SOHO, and WIND

    Science.gov (United States)

    Roberts, Craig E.

    2011-01-01

    Three heliophysics missions -- the Advanced Composition Explorer (ACE), Solar Heliospheric Observatory (SOHO), and the Global Geoscience WIND -- have been orbiting the Sun-Earth interior libration point L1 continuously since 1997, 1996, and 2004, respectively. ACE and WIND (both NASA missions) and SOHO (an ESA-NASA joint mission) are all operated from the NASA Goddard Space Flight Center (GSFC). While ACE and SOHO have been dedicated libration point orbiters since their launches, WIND has had also a remarkable 10-year career flying a deep-space, multiple lunar-flyby trajectory prior to 2004. That era featured 36 targeted lunar flybys with excursions to both L1 and L2 before its final insertion in L1 orbit. A figure depicts the orbits of the three spacecraft, showing projections of the orbits onto the orthographic planes of a solar rotating ecliptic frame of reference. The SOHO orbit is a quasi-periodic halo orbit, where the frequencies of the in-plane and out-of-plane motions are practically equal. Such an orbit is seen to repeat itself with a period of approximately 178 days. For ACE and WIND, the frequencies of the in-plane and out-of-plane motions are unequal, giving rise to the characteristic Lissajous motion. ACE's orbit is of moderately small amplitude, whereas WIND's orbit is a large-amplitude Lissajous of dimensions close to those of the SOHO halo orbit. As motion about the collinear points is inherently unstable, stationkeeping maneuvers are necessary to prevent orbital decay and eventual escape from the L1 region. Though the three spacecraft are dissimilar (SOHO is a 3-axis stabilized Sun pointer, WIND is a spin-stabilized ecliptic pole pointer, and ACE is also spin-stabilized with its spin axis maintained between 4 and 20 degrees of the Sun), the stationkeeping technique for the three is fundamentally the same. The technique consists of correcting the energy of the orbit via a delta-V directed parallel or anti-parallel to the Spacecraft-to-Sun line. SOHO

  12. 从日地系统L2出发借力月球飞越近地小行星%Near-Earth Asteroid Flyby Trajectories from the Sun-Earth L2 via Lunar Gravity Assist

    Institute of Scientific and Technical Information of China (English)

    何胜茂; 彭超; 高扬

    2016-01-01

    There are several flight options for the Chang’E-2 spacecraft after its remaining at the Sun-Earth L2 point, for example, impacting the Moon or recapture into lunar orbit, returning to Earth orbit or atmospheric reentry, heading for halo orbits of the Earth-Moon L1 or L2 or the Sun-Earth L1 point, as well as flying by near-Earth asteroids in interplanetary space (Finally, Chang’E-2 successfully implemented a close flyby of Toutatis, a potentially hazardous near-Earth asteroid, on Dec.13, 2012). The analyses of these flight options require designing preliminary transfer trajectories with total velocity impulses no more than 100 m/s in four-body dynamics, in which the motion of the spacecraft is influenced by the gravities of the Sun, Earth, and Moon. In this study, we shall present low-energy Toutatis flyby trajectories from a Sun-Earth L2 quasi-periodic orbit, specifically, via a single lunar gravity assist that is intentionally utilized for exploring potential benefits, compared with the direct transfer manner that is adopted in the practical mission. Compared with the direct transfer trajectories to the asteroid, lunar gravity assist is demonstrated to be capable of saving propellant for the Toutatis flyby mission, and the equivalent velocity impulses are 58.46 m/s.%对于停留在日地系统L2的“嫦娥2号”探测器,其后续飞行方案有多个选项,例如主动撞月或重返月球轨道、返回地球轨道或再入大气、飞往地月系统L1/L2或日地系统L1、进入深空飞越近地小行星(最终,“嫦娥2号”于2012年12月13日成功地实现了对Toutatis小行星的近距离飞越)。探讨上述的飞行方案需要对飞行轨道进行初步设计,总的速度脉冲限制在100 m/s以内并且需要考虑探测器同时受到太阳、地球、月球的引力作用。本研究设计了探测器从日地系统L2出发借力月球实现Toutatis小行星飞越的飞行方案,与直接飞越方案相比

  13. Near-Earth asteroid flyby trajectories from the Sun-Earth L2 for Chang'e-2's extended flight

    Science.gov (United States)

    Gao, Yang

    2013-02-01

    Driven by curiosity about possible flight options for the Chang'e-2 spacecraft after it remains at the Sun-Earth L2 point, effective approaches were developed for designing preliminary fuel-optimal near-Earth asteroid flyby trajectories. The approaches include the use of modified unstable manifolds, grid search of the manifolds' parameters, and a two-impulse maneuver for orbital phase matching and z-axis bias change, and are demonstrated to be effective in asteroid target screening and trajectory optimization. Asteroid flybys are expected to be within a distance of 2 × 107 km from the Earth owing to the constrained Earth-spacecraft communication range. In this case, the spacecraft's orbital motion is significantly affected by the gravities of both the Sun and the Earth, and therefore, the concept of the "heliocentric oscillating-Kepler orbit" is proposed, because the classical orbital elements of the flyby trajectories referenced in the heliocentric inertial frame oscillate significantly with respect to time. The analysis and results presented in this study show that, among the asteroids whose orbits are the most accurately predicted, "Toutatis", "2005 NZ6", or "2010 CL19" might be encountered by Chang'e-2 in late 2012 or 2013 with total impulses less than 100m/s.

  14. Near-Earth asteroid flyby trajectories from the Sun-Earth L2 for Chang'e-2's extended flight

    Institute of Scientific and Technical Information of China (English)

    Yang Gao

    2013-01-01

    Driven by curiosity about possible flight options for the Chang'e-2 spacecraft after it remains at the Sun-Earth L2 point,effective approaches were developed for designing preliminary fuel-optimal near-Earth asteroid flyby trajectories.The approaches include the use of modified unstable manifolds,grid search of the manifolds' parameters,and a two-impulse maneuver for orbital phase matching and z-axis bias change,and are demonstrated to be effective in asteroid target screening and trajectory optimization.Asteroid flybys are expected to be within a distance of 2 × 107 km from the Earth owing to the constrained Earth-spacecraft communication range.In this case,the spacecraft's orbital motion is significantly affected by the gravities of both the Sun and the Earth,and therefore,the concept of the“heliocentric oscillating-Kepler orbit” is proposed,because the classical orbital elements of the flyby trajectories referenced in the heliocentric inertial frame oscillate significantly with respect to time.The analysis and results presented in this study show that,among the asteroids whose orbits are the most accurately predicted,“Toutatis”,“2005 NZ6”,or “2010CL19” might be encountered by Chang'e-2 in late 2012 or 2013 with total impulses less than 100 m/s.

  15. Research on Control Method of Keeping Flight Formation by Using SDRE on the Sun-Earth Libration Points

    Directory of Open Access Journals (Sweden)

    He Zhenqi

    2017-01-01

    Full Text Available Keeping the flying formation of spacecraft is a key problem which needs to be solved in deep space exploration missions. In this paper, the nonlinear dynamic model of formation flying is established and a series of transformations are carried out on this model equation. By using SDRE (State-Dependent Riccati Equation algorithm, the optimal control of flying formation is realized. Compared with the traditional control method based on the average orbit elements and LQR (Linear Quadratic Regulator control method, the SDRE control method has higher control precision and is more suitable for the advantages of continuous control in practical engineering. Finally, the parameter values of the sun-earth libration point L2 are substituted in the equation and simulation is performed. The simulation curves of SDRE controller are compared with LQR controller. The results show that the SDRE controllers time cost is less than the LQR controllers and the former’s fuel consumption is less than the latter’s in the system transition process.

  16. Optimal Sunshade Configurations for Space-Based Geoengineering near the Sun-Earth L1 Point.

    Directory of Open Access Journals (Sweden)

    Joan-Pau Sánchez

    Full Text Available Within the context of anthropogenic climate change, but also considering the Earth's natural climate variability, this paper explores the speculative possibility of large-scale active control of the Earth's radiative forcing. In particular, the paper revisits the concept of deploying a large sunshade or occulting disk at a static position near the Sun-Earth L1 Lagrange equilibrium point. Among the solar radiation management methods that have been proposed thus far, space-based concepts are generally seen as the least timely, albeit also as one of the most efficient. Large occulting structures could potentially offset all of the global mean temperature increase due to greenhouse gas emissions. This paper investigates optimal configurations of orbiting occulting disks that not only offset a global temperature increase, but also mitigate regional differences such as latitudinal and seasonal difference of monthly mean temperature. A globally resolved energy balance model is used to provide insights into the coupling between the motion of the occulting disks and the Earth's climate. This allows us to revise previous studies, but also, for the first time, to search for families of orbits that improve the efficiency of occulting disks at offsetting climate change on both global and regional scales. Although natural orbits exist near the L1 equilibrium point, their period does not match that required for geoengineering purposes, thus forced orbits were designed that require small changes to the disk attitude in order to control its motion. Finally, configurations of two occulting disks are presented which provide the same shading area as previously published studies, but achieve reductions of residual latitudinal and seasonal temperature changes.

  17. Optimal Sunshade Configurations for Space-Based Geoengineering near the Sun-Earth L1 Point.

    Science.gov (United States)

    Sánchez, Joan-Pau; McInnes, Colin R

    2015-01-01

    Within the context of anthropogenic climate change, but also considering the Earth's natural climate variability, this paper explores the speculative possibility of large-scale active control of the Earth's radiative forcing. In particular, the paper revisits the concept of deploying a large sunshade or occulting disk at a static position near the Sun-Earth L1 Lagrange equilibrium point. Among the solar radiation management methods that have been proposed thus far, space-based concepts are generally seen as the least timely, albeit also as one of the most efficient. Large occulting structures could potentially offset all of the global mean temperature increase due to greenhouse gas emissions. This paper investigates optimal configurations of orbiting occulting disks that not only offset a global temperature increase, but also mitigate regional differences such as latitudinal and seasonal difference of monthly mean temperature. A globally resolved energy balance model is used to provide insights into the coupling between the motion of the occulting disks and the Earth's climate. This allows us to revise previous studies, but also, for the first time, to search for families of orbits that improve the efficiency of occulting disks at offsetting climate change on both global and regional scales. Although natural orbits exist near the L1 equilibrium point, their period does not match that required for geoengineering purposes, thus forced orbits were designed that require small changes to the disk attitude in order to control its motion. Finally, configurations of two occulting disks are presented which provide the same shading area as previously published studies, but achieve reductions of residual latitudinal and seasonal temperature changes.

  18. Early Mission Maneuver Operations for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission

    Science.gov (United States)

    Roberts, Craig; Case, Sara; Reagoso, John; Webster, Cassandra

    2015-01-01

    The Deep Space Climate Observatory mission launched on February 11, 2015, and inserted onto a transfer trajectory toward a Lissajous orbit around the Sun-Earth L1 libration point. This paper presents an overview of the baseline transfer orbit and early mission maneuver operations leading up to the start of nominal science orbit operations. In particular, the analysis and performance of the spacecraft insertion, mid-course correction maneuvers, and the deep-space Lissajous orbit insertion maneuvers are discussed, com-paring the baseline orbit with actual mission results and highlighting mission and operations constraints..

  19. Mission to the Sun-Earth L5 Lagrangian Point: An Optimal Platform for Space Weather Research

    Science.gov (United States)

    Vourlidas, Angelos

    2015-04-01

    The Sun-Earth Lagrangian L5 point is a uniquely advantageous location for space weather research and monitoring. It covers the "birth-to-impact" travel of solar transients; it enables imaging of solar activity at least 3 days prior to a terrestrial viewpoint and measures the solar wind conditions 4-5 days ahead of Earth impact. These observations, especially behind east limb magnetograms, will be a boon for background solar wind models, which are essential for coronal mass ejection (CME) and shock propagation forecasting. From an operational perspective, the L5 orbit is the space weather equivalent to the geosynchronous orbit for weather satellites. Optimal for both research and monitoring, an L5 mission is ideal for developing a Research-to-Operations capability in Heliophysics.

  20. A small mission concept to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science

    Science.gov (United States)

    Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer, M.; Vial, J.-C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; Pinto, R.; Auchère, F.; Harrison, R. A.; Eyles, C.; Gan, W.; Lamy, P.; Xia, L.; Eastwood, J. P.; Kong, L.; Wang, J.; Wimmer-Schweingruber, R. F.; Zhang, S.; Zong, Q.; Soucek, J.; An, J.; Prech, L.; Zhang, A.; Rochus, P.; Bothmer, V.; Janvier, M.; Maksimovic, M.; Escoubet, C. P.; Kilpua, E. K. J.; Tappin, J.; Vainio, R.; Poedts, S.; Dunlop, M. W.; Savani, N.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T.; DeForest, C.; Webb, D.; Lugaz, N.; Fuselier, S. A.; Dalmasse, K.; Tallineau, J.; Vranken, D.; Fernández, J. G.

    2016-08-01

    We present a concept for a small mission to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science. The proposed INvestigation of Solar-Terrestrial Activity aNd Transients (INSTANT) mission is designed to identify how solar coronal magnetic fields drive eruptions, mass transport and particle acceleration that impact the Earth and the heliosphere. INSTANT is the first mission designed to (1) obtain measurements of coronal magnetic fields from space and (2) determine coronal mass ejection (CME) kinematics with unparalleled accuracy. Thanks to innovative instrumentation at a vantage point that provides the most suitable perspective view of the Sun-Earth system, INSTANT would uniquely track the whole chain of fundamental processes driving space weather at Earth. We present the science requirements, payload and mission profile that fulfill ambitious science objectives within small mission programmatic boundary conditions.

  1. Sun-Earth Days

    Science.gov (United States)

    Thieman, J.; Ng, C.; Lewis, E.; Cline, T.

    2010-08-01

    Sun-Earth Day is a well-coordinated series of programs, resources and events under a unique yearly theme highlighting the fundamentals of heliophysics research and missions. A menu of activities, conducted throughout the year, inspire and educate participants. Sun-Earth Day itself can vary in date, but usually is identified by a celebration on or near the spring equinox. Through the Sun-Earth Day framework we have been able to offer a series of coordinated events that promote and highlight the Sun, its connection to Earth and the other planets. Sun-Earth Day events are hosted by educators, museums, amateur astronomers and scientists and occur at schools, community groups, parks, planetaria and science centers around the globe. Sun-Earth Day raises the awareness and knowledge of formal and informal education audiences concerning space weather and heliophysics. By building on the success of Sun-Earth Day yearly celebrations, we seek to affect people of all backgrounds and ages with the wonders of heliophysics science, discovery, and exploration in ways that are both tangible and meaningful to their lives.

  2. Sun, Earth and Sky

    CERN Document Server

    Lang, Kenneth R

    2006-01-01

    This Second Edition of Sun, Earth and Sky updates the popular text by providing comprehensive accounts of the most recent discoveries made by five modern solar spacecraft during the past decade. Their instruments have used sound waves to peer deep into the Sun’s inner regions and measure the temperature of its central nuclear reactor, and extended our gaze far from the visible Sun to record energetic outbursts that threaten Earth. Breakthrough observations with the underground Sudbury Neutrino Observatory are also included, which explain the new physics of ghostly neutrinos and solve the problematic mismatch between the predicted and observed amounts of solar neutrinos. This new edition of Sun, Earth and Sky also describes our recent understanding of how the Sun’s outer atmosphere is heated to a million degrees, and just where the Sun’s continuous winds come from. As humans we are more intimately linked with our life-sustaining Sun than with any other astronomical object, and the new edition therefore p...

  3. On the Transfer and Control of Space Probes Around the L1 Point of the Sun-Earth+Moon System

    Science.gov (United States)

    Hou, Xi-Yun; Liu, Lin

    2008-01-01

    The motion around the collinear libration points in the restricted three body problem is unstable. But there exist conditionally stable periodic orbits around these points. Special-purpose space probes located in the vicinity of these points (e.g., ISEE-3, SOHO) can benefit from this dynamical property, in regard to maintaining the orbit in position and the energy required of placing the probe in position. As an example, we study in this paper the launch and orbital control of a space probe around the L1 libration point in the system consisting of the Sun and the Earth-Moon. We present some theoretical and numerical simulations' results, which may serve as a basis for the realization of such a space probe in future.

  4. Lissajous Orbit Control for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission

    Science.gov (United States)

    Roberts, Craig; Case, Sarah; Reagoso, John

    2015-01-01

    DSCOVR Lissajous Orbit sized such that orbit track never extends beyond 15 degrees from Earth-Sun line (as seen from Earth). Requiring delta-V maneuvers, control orbit to obey a Solar Exclusion Zone (SEZ) cone of half-angle 4 degrees about the Earth-Sun line. Spacecraft should never be less than 4 degrees from solar center as seen from Earth. Following Lissajous Orbit Insertion (LOI), DSCOVR should be in an opening phase that just skirts the 4-degree SEZ. Maximizes time to the point where a closing Lissajous will require avoidance maneuvers to keep it out of the SEZ. Station keeping maneuvers should take no more than 15 minutes.

  5. Sun, Earth and Sky

    Science.gov (United States)

    Lang, Kenneth R.

    1995-01-01

    The Sun is enveloped by a hot, tenuous million-degree corona that expands to create a continuous solar wind that sweeps past all the planets and fills the heliosphere. The solar wind is modulated by strong gusts that are initiated by powerful explosions on the Sun, including solar flares and coronal mass ejections. This dynamic, invisible outer atmosphere of the Sun is currently under observation with the soft X-ray telescope aboard the Yohkoh spacecraft, whose results are presented. We also show observations from the Ulysses spacecraft that is now passing over the solar pole, sampling the solar wind in this region for the first time. Two other spacecraft, Voyager 1 and 2, have recently detected the outer edge of the invisible heliosphere, roughly halfway to the nearest star. Magnetic solar activity, the total radiative output from the Sun, and the Earth's mean global surface temperature all vary with the 11-year sunspot cycle in which the total number of sunspots varies from a maximum to a minimum and back to a maximum again in about 11 years. The terrestrial magnetic field hollows out a protective magnetic cavity, called the magnetosphere, within the solar wind. This protection is incomplete, however, so the Sun feeds an unseen world of high-speed particles and magnetic fields that encircle the Earth in space. These particles endanger spacecraft and astronauts, and also produce terrestrial aurorae. An international flotilla of spacecraft is now sampling the weak points in this magnetic defense. Similar spacecraft have also discovered a new radiation belt, in addition to the familiar Van Allen belts, except fed by interstellar ions instead of electrons and protons from the Sun.

  6. Floating-Point $L^2$-Approximations

    OpenAIRE

    Brisebarre, Nicolas; Hanrot, Guillaume

    2007-01-01

    International audience; Computing good polynomial approximations to usual functions is an important topic for the computer evaluation of those functions. These approximations can be good under several criteria, the most desirable being probably that the relative error is as small as possible in the $L^{\\infty}$ sense, i.e. everywhere on the interval under study. In the present paper, we investigate a simpler criterion, the $L^2$ case. Though finding a best polynomial $L^2$-approximation with ...

  7. Sensitivity Analysis of Initial Error for the Trajectory to the Sun-Earth Libration Point%飞往日-地动平衡点轨道初始误差敏感度分析

    Institute of Scientific and Technical Information of China (English)

    王亚敏; 乔栋; 崔平远

    2015-01-01

    对从环月轨道飞往日-地动平衡点轨道的转移轨道初始误差敏感度进行了数值仿真与分析。介绍了两种类型的转移轨道:长转移与短转移。建立初始速度误差与轨道末端偏差之间的数学关系式,采用数值计算获得了初始速度误差与轨道末端偏差量之间的线性关系曲线。通过建立轨道初始状态与末端状态量的一阶变分表达式,来说明始末偏差量呈线性关系的原因以及适用范围。研究表明,长转移轨道相较于短转移,对初始速度误差更为敏感,其始末偏差的线性关系适用范围更小。%The sensitivity of initial error for the transfer trajectory from lunar orbit to the Sun-Earth libration point orbit was calculated and analyzed.First,the short and long transfer trajectories for this kind of transfer issue were proposed.Then,the mathematical relation between initial error and terminal derivation was built.The relation is found to be linear by numerical calculation.Finally,the reason why the linear relation existed and its applicable conditions were explored by the first-order variation expression of initial error and terminal derivation.The result indicated that the long transfer is more sensitive to initial error than short transfer and that the applicable conditions for long transfer is stricter.

  8. 日地平动点卫星两脉冲转移轨道设计%Two impulses transfer trajectory design for Sun-Earth libration point missions

    Institute of Scientific and Technical Information of China (English)

    李明涛; 郑建华; 于锡峥; 高东

    2009-01-01

    Two impulses transfer trajectory design based on the least differential corrections method was studied, differential correction equation with the altitude and the flight path angle constraints was concluded, and the convergence of the method was discussed. Halo orbit around the L_1 libration point of the Sun-Earth system was taken as the objective orbit, two impulses transfer trajectory was designed in the framework of the circular restricted three-body problem. Effect of Halo orbit insertion (HOI) point and amplitude was studied in a systematic way, a strategy for the selection of HOI point was given, and the fast transfer trajectory for e-mergency was also studied. Numerical simulation shows that the proposed method is very effective, and transfer trajectory with moderate flight time can be obtained by choosing points on the near Earth side of Halo orbit as HOI point.%研究基于最小二乘微分修正方法的平动点卫星两脉冲转移轨道设计,推导了考虑高度和航迹角约束的微分修正公式,讨论了该方法的收敛性.以日地L_1点附近的Halo轨道为目标轨道,在圆型限制性三体问题模型下设计了其转移轨道,系统地研究了HOI(Halo Orbit Insertion)点和Halo轨道幅值对转移轨道的影响,给出了HOI点的选择策略,并讨论了应急情况下快速转移轨道设计.数值仿真验证了方法的有效性,选择Halo轨道靠近地球侧的点作HOI点可以获得飞行时间适中的转移轨道.

  9. Sun-Earth Day Connects History, Culture and Science

    Science.gov (United States)

    Cline, T.; Thieman, J.

    2003-12-01

    The NASA Sun-Earth Connection Education forum annually promotes and event called Sun-Earth Day: a national celebration of the Sun, the space around the Earth (geospace), and how all of it affects life on our planet. For the past 3 years this event has provided a venue by which classrooms, museums, planetaria, and at NASA centers have had a sensational time sharing stories, images, and activities related to the Sun-Earth connections and the views o fthe Sun from Earth. Each year we select a different theme by which NASA Space Science can be further related to cross-curricular activities. Sun-Earth Day 2002, "Celebrate the Equinox", drew parallels between Native American Cultures and NASA's Sun-Earth Connection research via cultural stories, interviews, web links, activities and Native American participation. Sun-Earth Day 2003, "Live From the Aurora", shared the beauty of the Aurora through a variety of activities and stories related to perspectives of Northern Peoples. Sun-Earth Day 2004 will share the excitement of the transit of Venus through comparisons of Venus with Earth and Mars, calculations of the distances to nearby stars, and the use of transits to identify extra-solar planets. Finally, Sun-Earth Day 2005 will bring several of these themes together by turning our focus to the history and culture surrounding ancient observatories such as Chaco Canyon, Machu Picchu, and Chichen Itza.

  10. Transfer trajectory design between L2 in Sun-Earth system and L1 in Sun-Mars system%日地系L2点与日火系L1点转移轨道设计

    Institute of Scientific and Technical Information of China (English)

    吕敬; 张明明; 张永威

    2013-01-01

    将太阳-地球-火星-飞行器组成的四体问题分解成由太阳-地球-飞行器和太阳-火星-飞行器两个共面圆形限制性三体问题,设计日地系L2点与日火系L1点Lyapunov轨道之间的转移轨道,该转移轨道可以作为探测火星时的低能中间转移轨道.采用Richardson三阶近似解作为初始值,运用微分修正方法分别得到两个不同三体系统下拉格朗日点的精确Lyapunov轨道.基于Lyapunov轨道不变流形以及微分修正方法,设计了日地系L2点与日火系L1点间的转移轨道.将所得结果与基于Halo轨道不变流形设计的转移轨道进行了对比.结论表明:利用Lyapunov轨道不变形设计探火中间转移轨道相较于利用Halo轨道不变流形设计探火中间转移轨道在能量消耗以及飞行时间上都存在优势.

  11. Sun-Earth Day 2005: Ancient Observatories: Timeless Knowledge

    Science.gov (United States)

    Thieman, J. R.; Cline, T.; Lewis, E.; Hawkins, I.; Odenwald, S.; Mayo, L.

    2005-05-01

    The NASA Sun-Earth Connection Education Forum (SECEF) annually promotes an event called Sun-Earth Day. For Sun-Earth Day 2005 SECEF has selected a theme called "Ancient Observatories: Timeless Knowledge. This year's Sun-Earth Day theme is your ticket to a fascinating journey through time as we explore centuries of sun watching by a great variety of cultures. From ancient solar motion tracking to modern solar activity monitoring the Sun has always occupied an important spot in mankind's quest to understand the Universe. Sun-Earth Day events usually are centered on the spring equinox around March 21, but this year there has already been a webcast from the San Francisco Exploratorium and the Native American ruins at Chaco Canyon, New Mexico on the day of winter solstice 2004. There will be another webcast on March 20 live from Chichen Itza, Mexico highlighting the solar alignment that makes a serpent appear on one of the ancient pyramids. The website http://sunearthday.nasa.gov has been developed to provide the necessary resources and opportunities for participation by scientists and educators in giving school or general public programs about Sun-Earth Day. The goal is to involve as much of the student population and the public in this event as possible and to help them understand the importance of the Sun for ancient and modern peoples. Through engaging activities available on the website, classrooms and museums can create their own event or participate in one of the opportunities we make available. Scientists, educators, amateur astronomers, and museums are invited to register on the website to receive a free packet of materials about Sun-Earth Day for use in making presentations or programs about the event. Past and future Sun-Earth Days will be discussed as well.

  12. Sun-Earth Connection EPO's with Multiple Uses and Audiences

    Science.gov (United States)

    Foster, S. Q.; Johnson, R. M.; Russell, R.; Lu, G.; Richmond, A.; Maute, A.; Haller, D.; Conery, C.; Bintner, G.; Kiessling, D.; Hughes, W. J.

    2005-05-01

    The three-year life of an EPO grant can be a journey guided by clear goals and enriched by collaborative and outreach opportunities connecting Space sciences to Earth sciences for both K-12 and public audiences. This point is illustrated by two EPO projects funded by NASA Sun-Earth Connection research grants to the High Altitude Observatory (HAO) at the National Center for Atmospheric Research. They are entering their final year coordinated by the Office of Education and Outreach at University Corporation for Atmospheric Research. The content focus of both projects is well aligned with HAO's research mission and the expertise of our scientists, addressing solar dynamics, space weather, and the impacts of solar events on the magnetosphere, as well as societies inhabiting Earth's surface. The first project (Gang Lu, PI) develops presentation resources, inquiry activities, and tips that will help HAO scientists be better prepared to visit K-12 classrooms. Unexpectedly, the simultaneous development of a Teachers' Guide to NCAR's new Climate Discovery exhibit, which takes an Earth system approach to climate and global change, has created a niche for this EPO resource to be revised and repurposed for a needed unit in the guide about the exhibit's graphic panels on Sun-Earth connections. The second project (Art Richmond, PI) engages two high school "Teachers in Residence" to develop resources they can utilize with their students. Excited by exceptional educational graphics and animations in the new Physics of the Aurora: Earth Systems module co-produced by HAO and the COMET Program for advanced undergraduate courses, they chose to adapt appropriate sections of the module to enrich Earth science and math concepts addressed in their 9th and 10th grade astronomy and general physics classes. Simultaneously, the Windows to the Universe web site, which continuously updates space science content and is now developing a new Space Weather section with support from the Center for

  13. Application of Foreign Spacecrafts of Sun-Earth Libration Points and Manners of Transfer Trajectory%国外日-地动平衡点卫星应用及转移轨道实现方式

    Institute of Scientific and Technical Information of China (English)

    周天帅; 李东; 陈新民; 杨虎军

    2004-01-01

    圆形限制性三体问题中存在5个动平衡点.其中日-地系统中共线平衡点L1和L2是近十几年来国外研究热点.首先介绍了5个平衡点的位置关系及卫星应用,接着从理论上简单比较了Halo轨道和Lissajous轨道的区别,指出Halo轨道和Lissajous轨道是线性化偏差方程的特解.介绍国外日-地动平衡点卫星应用情况,分析了转移轨道的两种可行方式.

  14. Sun-Earth Day - Teaching Heliophysics Through Education Technology

    Science.gov (United States)

    Thieman, J.; Cline, T.; Lewis, E.

    2010-01-01

    Sun-Earth Day (SED) is an Education and Outreach program supported by the U.S, National Aeronautics and Space Administration (NASA). The intent of the program is to teach students and the general public about Heliophysics (the science of the study of the Sun, how it varies, and how solar dynamics affect the rest of the solar system, especially the Earth). The program was begun ten years ago. Each year since that time a particular day has been designated as "Sun-Earth Day ,,. Usually the day of the spring equinox (March 20 or 21) is Sun-Earth Day, but other days have been used as well. Each year a theme is chosen relating to Heliophysics and events reflecting that theme are planned not only for Sun-Earth Day, but for the entire year. From the very beginning educational technology was emphasized in the events in order to effectively reach wide audiences with the SED message. The main approach has been to have a "webcast" related to each year's theme, often from a location that supports the theme as well. For example, a webcast took place from the Mayan pyramids at Chichen Itza, Mexico to highlight the theme of "Ancient Observatories, Timeless Knowledge". Webcasts were not the only technology employed, however. Many of the themes centered on the dynamic nature of the Sun and the effects that solar storms can have on interplanetary space and in our day-to-day life on Earth. Activities for tracking when solar storms happen and how they affect the Earth were developed and brought together in an educational package called Space Weather Action Centers. This project is explained in more detail in another presentation in this session being given by Norma Teresinha Oliveira Reis. Recent Sun-Earth Days have utilized "social networking" technologies to reach widespread groups on the internet. Podcasts, Vodcasts, Facebook, Twitter, and Second Life are the types of network technologies being employed now. The NASA Distance learning Network is another method for bringing Sun-Earth

  15. International Sun-Earth Explorer (ISEE)

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    Series of three US satellites designed to study the solar wind and its interaction with the Earth's magnetosphere. ISEE-1 and 2 were placed into highly elliptical Earth orbits. ISEE-3 was placed in a halo orbit at the L1 Lagrangian point between the Sun and Earth. It gave advance warning of solar storms heading towards Earth. (See also INTERNATIONAL COMETARY EXPLORER and EXPLORER.)...

  16. Transfer Trajectories to L3 Libration Point of Sun-Earth System%基于准流形方法日地系L3点转移轨道设计

    Institute of Scientific and Technical Information of China (English)

    潘迅; 泮斌峰

    2015-01-01

    针对深空探测中轨道转移时间长且能量消耗较大的问题,提出基于准流形实现从地球停泊轨道到日地系L3点转移轨道的设计方法.在日地限制性三体问题模型下,在L1点或L2点Halo轨道上施加扰动推力,构造准流形,利用其非线性三体动力学特性,通过霍曼转移轨道与近地轨道进行拼接,使航天器进入准流形后能够无动力滑行到L3点附近区域.在准流形与L3点周期轨道交点,施加速度脉冲,使航天器进入相应周期轨道,从而完成轨道转移.仿真结果表明,利用该方法所得结果与基于不变流形的转移轨道相比,能将速度增量从4 398 m/s减少为4 014 m/s,并将转移时间从9年以上缩短到7.3年以内,有效地提高了航天器的工作效率.

  17. CUNY Sun-Earth Research, Space Climate

    Science.gov (United States)

    Cotten, D. E.; Cheung, T. D.; Marchese, P. J.; Johnson, L. P.; Austin, S.; Tremberger, G.

    2007-05-01

    Faculty and students at Queensborough Community College and Medgar Evers College of the City University of New York (CUNY) have, over several years now, employed simple software familiar to most undergraduate students to perform useful calculations, including statistical analyses, regarding various geophysical phenomena. Topics have included Space Weather, Interplanetary Magnetic Field (IMF) direction and strength fluctuations, geomagnetic and ionospheric responses to solar flares, and Coronal Mass Ejection (CME) events. Our statistical analyses have utilized second-order measures of fluctuation of the IMF strength, especially what we now call the Cheung number: the number of times that the value of Sigma-B, as provided by the ACE (Advanced Composition Explorer) data, has exceeded 0.5nT during a 6 hour interval. We have also utilized the Higuchi fractal dimension of various somewhat random fluctuations, including Sigma-B and the brightness or strength of adjacent pixels or data points in somewhat random data sequences in time or spatial dimension, including IMF fluctuations and SOHO (Solar Heliographic Observer) images of the Sun. These we have correlated with each other and with such variables as SEP (Solar Energetic Particle) peak flux, TEC (Total Electron Content) of the ionosphere, and Dst (Disturbance storm-time) in the geomagnetic field. Recent results indicate that the IMF fluctuation measures are well correlated with the SEP peak flux, the Dst, and TEC. Higuchi fractal analysis of SOHO photospheric ultraviolet brightness indicates, consistent with concomitant increased chaos or randomness of photospheric brightness, an increased likelihood of solar flare events or CME affecting interplanetary space and the earth's magnetosphere/ionosphere/atmosphere.

  18. Thermal design of solar observer at L1 Lagrangian point in Sun-Earth system%日-地系拉格朗日 L1点太阳观测器热设计

    Institute of Scientific and Technical Information of China (English)

    王祥; 李义; 杨献伟

    2013-01-01

    对将运行于日-地L1点的太阳观测器进行了热设计,重点论述了日-地L1点的轨道外热流计算和Lyman α日冕仪(LACI)反射镜M2光阱、Lyman α日冕成像仪(LADI)滤光片组件、CCD组件、电箱、观测器主体等部分的热设计方案。通过在探测器对日面设置集热板,将观测器的主动加热功耗降低了73%;选用预埋热管的设计方案解决了对日定向观测导致的框架温差问题。仿真分析结果表明,在对日高温工作、对日低温工作、低温存储、轨道转移等4个极端工况下,观测器各组件温度均满足指标要求。该热设计方案以较低的加热功耗,解决了太阳观测器在轨工作阶段的散热、轨道转移阶段的保温等问题,满足CCD焦面工作温度<-50℃的要求。%To ensure the temperature requirements of the solar observer working at L 1 Lagrangian point , the thermal design for Lyman αCoronagraphy Imager(LACI) and Lyman αDisk Image(LADI) was carried out, and the heat flux of the orbit was calculated .The thermal designs of light trap , filter components , detector com-ponents, electric box, and entirety of the observer were discussed in details .By using collector panels settled in the side facing to the Sun , the active heating power could be reduced by 73%.In order to reduce the tem-perature gradient caused by long-term observation facing to the sun , a heat pipe was embedded in the frame . Simulation results show that all conditions meet the temperature indicator in 4 typical cases .The thermal de-sign system with a low active power solves many problems , such as the cooling of the observer in orbit , insula-tion during orbital transfer phase , and meets the working temperature requirement of below -50℃for a CCD plane .

  19. Mass-loss through the L2 Lagrange point - application to main-sequence EMRI

    Science.gov (United States)

    Linial, Itai; Sari, Re'em

    2017-08-01

    We consider stable mass transfer from the secondary to the primary of an extreme mass ratio binary system. We show that when the mass transfer is sufficiently fast, mass leakage occurs through the outer Lagrange point L2, in addition to the usual transfer through L1. We provide an analytical estimate for the mass leakage rate through L2 and find the conditions in which it is comparable to the mass transfer rate through L1. Focusing on a binary system of a main-sequence star and a supermassive black hole, driven by the emission of gravitational radiation, we show that it may sustain stable mass transfer, along with mass-loss through L2. If such a mass transferring system occurs at our Galactic Centre, it produces a gravitational wave signal detectable by future detectors, such as Laser Interferometer Space Antenna (LISA). The signal evolves according to the star's adiabatic index and cooling time. For low-mass stars, the evolution is faster than the Kelvin-Helmholtz cooling rate driving the star out of the main-sequence. In some cases, the frequency and amplitude of the signal may both decrease with time, contrary to the standard chirp of a coalescing binary. Mass-loss through L2, when occurs, decreases the evolution time-scale of the emitted gravitational wave signal by up to a few tens of per cent. We conclude that L2 mass ejection is a crucial factor in analysing gravitational waves signals produced by such systems.

  20. Sun-earth connection education through modern views of ancient

    Science.gov (United States)

    Thieman, J. R.

    The NASA Sun-Earth Connection Education Forum (SECEF) has the responsibility of using the latest science results from the study of solar physics, space physics, and aeronomy to inspire students in the classroom and to inform the public in general. SECEF works with NASA's Sun-Earth Connection spaceflight missions to accomplish this goal. Each year the missions and SECEF combine to promote their science through a major event designed to attract the attention of all. In late 2004 and 2005 the event will be the study of solar observatories created by ancient peoples and a comparison of their knowledge and culture to present understanding. Two solar observatory sites will be featured, Chaco Canyon in the U.S. and Chichen Itza in Mexico. There are many other places throughout the world that could also be featured as solar observatories and some of these may be described on the SECEF web site or used in future occurrences. Special emphasis is placed on events associated with the solstice and equinox dates. It is hoped that there will be happenings around the world on these days and SECEF will work with many museums, science centers, and other groups to help make this happen. Plans for the 2005 Ancient Observatories event and possible future events on the same subject will be described.

  1. Lunar and Lagrangian Point L1 L2 CubeSat Communication and Navigation Considerations

    Science.gov (United States)

    Schaire, Scott; Wong, Yen F.; Altunc, Serhat; Bussey, George; Shelton, Marta; Folta, Dave; Gramling, Cheryl; Celeste, Peter; Anderson, Mile; Perrotto, Trish; hide

    2017-01-01

    CubeSats have grown in sophistication to the point that relatively low-cost mission solutions could be undertaken for planetary exploration. There are unique considerations for lunar and L1/L2 CubeSat communication and navigation compared with low earth orbit CubeSats. This paper explores those considerations as they relate to the Lunar IceCube Mission. The Lunar IceCube is a CubeSat mission led by Morehead State University with participation from NASA Goddard Space Flight Center, Jet Propulsion Laboratory, the Busek Company and Vermont Tech. It will search for surface water ice and other resources from a high inclination lunar orbit. Lunar IceCube is one of a select group of CubeSats designed to explore beyond low-earth orbit that will fly on NASA’s Space Launch System (SLS) as secondary payloads for Exploration Mission (EM) 1. Lunar IceCube and the EM-1 CubeSats will lay the groundwork for future lunar and L1/L2 CubeSat missions. This paper discusses communication and navigation needs for the Lunar IceCube mission and navigation and radiation tolerance requirements related to lunar and L1/L2 orbits. Potential CubeSat radios and antennas for such missions are investigated and compared. Ground station coverage, link analysis, and ground station solutions are also discussed. This paper will describe modifications in process for the Morehead ground station, as well as further enhancements of the Morehead ground station and NASA Near Earth Network (NEN) that are being considered. The potential NEN enhancements include upgrading current NEN Cortex receiver with Forward Error Correction (FEC) Turbo Code, providing X-band uplink capability, and adding ranging options. The benefits of ground station enhancements for CubeSats flown on NASA Exploration Missions (EM) are presented. This paper also describes how the NEN may support lunar and L1/L2 CubeSats without any enhancements. In addition, NEN is studying other initiatives to better support the CubeSat community

  2. A Note on Dynamics About the Coherent Sun–Earth–Moon Collinear Libration Points

    Science.gov (United States)

    Olikara, Zubin P.; Gómez, Gerard; Masdemont, Josep J.

    Orbits about the Sun-Earth libration points are perturbed by the Moon, and orbits about the Earth-Moon libration points are perturbed by the Sun. We study both situations in the framework of a single, coherent model, the Hill restricted four-body problem. This model is presented in a Sun-Earth rotating reference frame to complement its earlier Earth-Moon frame formulation. We provide an overview of the planar quasi-periodic orbits that originate from the L 1 and L 2 Lyapunov periodic orbits in Hill's problem and the circular restricted three-body problem. The role of resonances is also discussed.

  3. High-Performance Data Analysis Tools for Sun-Earth Connection Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Interactive Data Language (IDL) is a standard tool used by many researchers in observational fields. Present day Sun-Earth Connection missions like SOHO, or...

  4. Blow-up solutions for L 2 supercritical gKdV equations with exactly k blow-up points

    Science.gov (United States)

    Lan, Yang

    2017-08-01

    In this paper we consider the slightly L 2-supercritical gKdV equations \\partialt u+(uxx+u\\vert u\\vert p-1)_x=0 , with the nonlinearity 5 and 0L 2-supercritical gKdV equations. Such solutions can be viewed as solutions with a single blow-up point. In this paper we will prove the existence of solutions with multiple blow-up points, and give a description of the formation of the singularity near the blow-up time.

  5. Phasing Delta-V for transfers from Sun-Earth halo orbits to the Moon

    Science.gov (United States)

    Chen, Hongru; Kawakatsu, Yasuhiro; Hanada, Toshiya

    2016-10-01

    Inspired by successful extended missions such as the ISEE-3, an investigation for the extended mission that involves a lunar encounter following a Sun-Earth halo orbit mission is considered valuable. Most previous studies present the orbit-to-orbit transfers where the lunar phase is not considered. Intended for extended missions, the present work aims to solve for the minimum phasing ∆V for various initial lunar phases. Due to the solution multiplicity of the two-point boundary value problem, the general constrained optimization algorithm that does not identify multiple feasible solutions is shown to miss minima. A two-step differential corrector with a two-body Lambert solver is developed for identifying multiple solutions. The minimum ∆V associated with the short-way and long-way approaches can be recovered. It is acquired that the required ∆V to cover all initial lunar phases is around 45 m/s for the halo orbit with out-of-plane amplitude Az greater than 3.5×105 km, and 14 m/s for a small halo orbit with Az=1×105 km. In addition, the paper discusses the phasing planning based on the ∆V result and the shift of lunar phase with halo orbit revolution.

  6. Sun-Earth Day: Growth and Impact of NASA E/PO Program

    Science.gov (United States)

    Hawkins, I.; Thieman, J.

    2004-12-01

    Over the past six years, the NASA Sun-Earth Connection Education Forum has sponsored and coordinated education public outreach events to highlight NASA Sun-Earth Connection research and discoveries. Our strategy involves using celestial phenomena, such as total solar eclipses and the Transit of Venus to celebrate Sun-Earth Day, a popular Education and Public Outreach international program. Sun-Earth Day also focuses attention on Equinoxes and Solstices to engage K-12 schools and the general public in space science activities, demonstrations, and interactions with space scientists. In collaboration with partners that include the Exploratorium, Maryland Science Center, NASA Connect, Sun-Earth Connection missions, Ideum, and others, we produce webcasts, other multi-media, and print resources for use by school and informal educators nation-wide. We provide training and professional development to K-12 educators, museum personnel, amateur astronomers, Girl Scout leaders, etc., so they can implement their own outreach programs taking advantage of our resources. A coordinated approach promotes multiple programs occurring each year under a common theme. We will report lessons learned from several years of experience, and strategies for growth and sustainability. We will also share our plans for "Ancient Observatories - Timeless Knowledge" our theme for Sun-Earth Day 2005, which will feature solar alignments at ancient sites that mark the equinoxes and/or solstices. The video and webcast programming will feature several sites including: Chaco Canyon (New Mexico), Hovenweep (Utah), and Chichen Itza (Mexico). Many of these sites present unique opportunities to develop authentic cultural connections to Native Americans, highlighting the importance of the Sun across the ages.

  7. Orbital mechanics near Lagrange's points

    OpenAIRE

    Utashima, Masayoshi; 歌島 昌由

    1997-01-01

    The first libration-point satellite ISEE-3 (International Sun-Earth Explorer-3) was launched in 1978. Though, no libration-point satellites were realized after the launch of the ISEE-3, NASA launched the ESA's Solar and Heliospheric Observatory (SOHO) spacecraft into the halo orbit in the sun-earth system in late 1995. The halo orbit in the sun-earth system is adequate for missions such as solar observation, astronomical observation, NEO (Near Earth Objects) observation, communications with t...

  8. Earth-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5

    DEFF Research Database (Denmark)

    Gopalswamy, Nat; Davila, Joseph M.; Auchère, Frédéric

    2011-01-01

    . The Earth-Affecting Solar Causes Observatory (EASCO) is a proposed mission to be located at the Sun-Earth L5 that overcomes these deficiencies. The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center, to see how the mission can be implemented...

  9. Orbit Determination of Spacecraft in Earth-Moon L1 and L2 Libration Point Orbits

    Science.gov (United States)

    Woodard, Mark; Cosgrove, Daniel; Morinelli, Patrick; Marchese, Jeff; Owens, Brandon; Folta, David

    2011-01-01

    The ARTEMIS mission, part of the THEMIS extended mission, is the first to fly spacecraft in the Earth-Moon Lissajous regions. In 2009, two of the five THEMIS spacecraft were redeployed from Earth-centered orbits to arrive in Earth-Moon Lissajous orbits in late 2010. Starting in August 2010, the ARTEMIS P1 spacecraft executed numerous stationkeeping maneuvers, initially maintaining a lunar L2 Lissajous orbit before transitioning into a lunar L1 orbit. The ARTEMIS P2 spacecraft entered a L1 Lissajous orbit in October 2010. In April 2011, both ARTEMIS spacecraft will suspend Lissajous stationkeeping and will be maneuvered into lunar orbits. The success of the ARTEMIS mission has allowed the science team to gather unprecedented magnetospheric measurements in the lunar Lissajous regions. In order to effectively perform lunar Lissajous stationkeeping maneuvers, the ARTEMIS operations team has provided orbit determination solutions with typical accuracies on the order of 0.1 km in position and 0.1 cm/s in velocity. The ARTEMIS team utilizes the Goddard Trajectory Determination System (GTDS), using a batch least squares method, to process range and Doppler tracking measurements from the NASA Deep Space Network (DSN), Berkeley Ground Station (BGS), Merritt Island (MILA) station, and United Space Network (USN). The team has also investigated processing of the same tracking data measurements using the Orbit Determination Tool Kit (ODTK) software, which uses an extended Kalman filter and recursive smoother to estimate the orbit. The orbit determination results from each of these methods will be presented and we will discuss the advantages and disadvantages associated with using each method in the lunar Lissajous regions. Orbit determination accuracy is dependent on both the quality and quantity of tracking measurements, fidelity of the orbit force models, and the estimation techniques used. Prior to Lissajous operations, the team determined the appropriate quantity of tracking

  10. Sun-Earth Day: Reaching the Education Audience by Informal Means

    Science.gov (United States)

    Thieman, J.; Lewis, E.; Cline, T.

    2010-01-01

    For ten years the Sun-Earth Day program has promoted Heliophysics education to ever larger audiences through events centered on attractive annual themes. What originally started out as a one day event quickly evolved into a series of programs and events that occur throughout the year culminating with a celebration on or near the Spring Equinox. The events are often formal broadcasts or webcasts seeking to convey the science behind the latest solar-terrestrial mission discoveries. This has been quite successful, but it is clear that the younger generation increasingly depends on social networking approaches and informal news transmission for learning what is happening in the world around them. For 2010, the Sun-Earth Day team put emphasis on using informal approaches to bring the theme to the audience. The main event, a webcast from the NASA booth at the National Science Teachers Association (NSTA) annual meeting by the NASA EDGE group, took a lighthearted and offbeat approach to interviewing scientists and educators about Heliophysics news. NASA EDGE programs are unscripted and unpredictable, and that represents a different approach to getting the message across. The webcast was supplemented by a number of social networking avenues. The Sun-Earth Day program explored a wide range of social media applications including Facebook, Twitter, NING, podcasting, iPhone apps, etc. Each of these offers unique and effective methods to promote Heliophysics content and mission related highlights. The facebook site was quite popular and message posting there told the Sun-Earth Day story piece by piece. The same could be said of twittering and the tweetup held at the NSTA site. Has all of this been effective? Results are still being gathered, but anecdotal responses from the world seem very positive. What other methods might be used in the future to bring the science to a personal hands-on, interactive experience? Outcomes: Participants will: (1) Be introduced to the Sun-Earth

  11. Climate and weather of the Sun-Earth system (CAWSES) highlights from a priority program

    CERN Document Server

    Lübken, Franz-Josef

    2012-01-01

    CAWSES (Climate and Weather of the Sun-Earth System) is the most important scientific program of SCOSTEP (Scientific Committee on Solar-Terrestrial Physics). CAWSES has triggered a scientific priority program within the German Research Foundation for a period of 6 years. Approximately 30 scientific institutes and 120 scientists were involved in Germany with strong links to international partners. The priority program focuses on solar influence on climate, atmospheric coupling processes, and space climatology. This book summarizes the most important results from this program covering some impor

  12. Momentum Management of Chang'e-2 Satellite on L2 Point%“嫦娥二号”卫星L2点角动量管理

    Institute of Scientific and Technical Information of China (English)

    戴居峰; 徐红兵; 崔雁; 薛锐

    2013-01-01

    对“嫦娥二号”(CE-2)卫星进入环绕日地拉格朗日L2点的李萨如轨道后卫星喷气卸载所产生的影响进行了研究.提出了一种利用光压力矩辅助卫星太阳电池翼角度调整进行角动量管理的方法.在轨试验表明,太阳光压强度足够对飞行在L2点环绕轨道上的CE-2卫星进行角动量管理,可以大幅度减少动量轮在轨喷气卸载的次数,有利于CE-2卫星的轨道维持.%Since Chang'e-2 (CE-2) satellite entered the Lissajous orbit surrounding the Earth-Sun Lagrange point L2,the effect of jet uninstall was studied.A momentum management method by light pressure was given.The in orbit test shows that the Solar light pressure is strong enough to unload the momentum of CE-2 satellite,which is surrounding the L2 point.This method can substantially reduce the number of jet uninstall,and benefit the orbit maintenance of CE-2 satellite.

  13. Perceived Learning Difficulty and Actual Performance: Explicit and Implicit Knowledge of L2 English Grammar Points among Instructed Adult Learners

    Science.gov (United States)

    Silva, Luis Humberto Rodríguez; Roehr-Brackin, Karen

    2016-01-01

    This article draws on an approach that conceptualizes L2 learning difficulty in terms of implicit and explicit knowledge. In a study with first language Mexican Spanish university-level learners (n = 30), their teachers (n = 11), and applied linguistics experts (n = 3), we investigated the relationship between (a) these groups' difficulty…

  14. Student Mastery of the Sun-Earth-Moon System in a Flipped Classroom of Pre-service Elementary Education Students

    Science.gov (United States)

    Larsen, Kristine

    2014-01-01

    One of the current trends in pedagogy at all levels(K-college) is the so-called ‘flipped classroom’, in which students prepare for a class meeting through self-study of the material. It is based on a rejection of the classic model of the faculty member as the ‘sage on the stage’ instead, responsibility for learning shifts to the individual student. The faculty member takes on the role of learning facilitator or mentor, and focuses the students’ learning by crafting and administering timely formative assessments (in multiple formats and applied multiple times) that aid both students and the faculty member in tracking the students’ mastery of the learning outcomes. In a flipped, freshman-only, section of SCI 111 Elementary Earth-Physical Sciences (a required introductory science course for pre-service elementary school teachers) the students learned through a combination of individual and group hands-on in-class activities, technology (including PowerPoint presentations and short videos viewed prior to attending class), in-class worksheets, and in-class discussions. Students self-differentiated in how they interacted with the available teaching materials, deciding which activities to spend the most time on based on their individual needs (based on an online quiz taken the night before the class period, and their personal self-confidence with the material). Available in-class activities and worksheets were developed by the faculty member based on student scores on the online quiz as well as personal messages submitted through the course management system the night before the class meeting. While this placed a significant burden on the faculty member in terms of course preparation, it allowed for just-in-time teaching to take place. This poster describes the results of student mastery of content centered on the sun-earth-moon system (specifically seasons, moon phases, and eclipses) as compared to traditional classroom sections.

  15. Visualizing Sun-Earth-Moon Relationships through Hands-On Modeling

    Science.gov (United States)

    Morton, Abby

    2013-04-01

    "Tell me and I forget, teach me and I may remember, involve me and I learn." -Benjamin Franklin Understanding the spatial relationships between the sun, Earth and Moon is fundamental to any basic earth science education. Since both of the following concepts involve shadows on three-dimensional spheres, seeing them on paper is not often conducive to understanding. In the first activity, students use five Styrofoam balls painted to look like the sun and the four positions of the earth in each season. Students position the Earth-balls in their correct order around the sun and translate what they are seeing onto paper. In the second activity, students hold up a Styrofoam ball painted half white, half black. A picture of the sun is projected at the front of the classroom. They move the ball around their heads as if they were the Earth, keeping the lit side of the moon always facing the sun. They then draw the phases of the moon as they see them.

  16. ITM-Related Data and Model Services at the Sun Earth Connection Active Archive (SECAA)

    Science.gov (United States)

    McGuire, R.; Bilitza, D.; Kovalick, T.; Papitashvili, N.; Candey, R.; Han, D.

    2004-12-01

    NASA's Sun Earth Connection Active Archive (SECAA) provides access to a large volume of data and models that are of relevance to Ionospheric, Thermospheric and Mesospheric (ITM) physics. SECAA has developed a number of web systems to facilitate user access to this important data source and is making these services available through Web Services (or Application Programming Interfaces, API) directly to applications such as VxOs. The Coordinated Data Analysis web (CDAWeb) lets user plot data using a wide range of parameter display options including mapped images and movies. Capabilities also include parameter listings and data downloads in CDF and ASCII format. CDAWeb provides access to data from most of NASA's currently operating space science satellites and many of the earlier missions; of special ITM interest are DE-2, ISIS, FAST, Equator-S, and TIMED. SECAA maintains and supports the Common Data Format (CDF) including software to read and write CDF files. Most recently translator services have been added for CDF translations to/from netCDF, FITS, CDFXML, and ASCII. The SSCWeb interface enables users to plot orbits for the majority of space physics satellites (including TIMED, UARS, DMSP, NOAA, LANL etc.) and to query for magnetic field line conjunctions between multiple spacecraft and ground stations and for magnetic region occupancy. Recently an Interactive 3-D orbit viewer was added to SSCWeb. Access to legacy data from older ITM satellite missions is provided through the ATMOWeb system with the ability to generate plots and download data subsets in ASCII format. Recently added capabilities include the option to filter the data using an upper and lower boundary for any one of the data set parameters. We will also present the newest version of the web portal to SECAA's models catalog, ftp archive, and web interfaces. The web interfaces (Fortran, C, Java) let users compute, list, plot, and download model parameters for selected models (IRI, IGRF, MSIS/CIRA, AE

  17. High-Performance Data Analysis Tools for Sun-Earth Connection Missions

    Science.gov (United States)

    Messmer, Peter

    2011-01-01

    The data analysis tool of choice for many Sun-Earth Connection missions is the Interactive Data Language (IDL) by ITT VIS. The increasing amount of data produced by these missions and the increasing complexity of image processing algorithms requires access to higher computing power. Parallel computing is a cost-effective way to increase the speed of computation, but algorithms oftentimes have to be modified to take advantage of parallel systems. Enhancing IDL to work on clusters gives scientists access to increased performance in a familiar programming environment. The goal of this project was to enable IDL applications to benefit from both computing clusters as well as graphics processing units (GPUs) for accelerating data analysis tasks. The tool suite developed in this project enables scientists now to solve demanding data analysis problems in IDL that previously required specialized software, and it allows them to be solved orders of magnitude faster than on conventional PCs. The tool suite consists of three components: (1) TaskDL, a software tool that simplifies the creation and management of task farms, collections of tasks that can be processed independently and require only small amounts of data communication; (2) mpiDL, a tool that allows IDL developers to use the Message Passing Interface (MPI) inside IDL for problems that require large amounts of data to be exchanged among multiple processors; and (3) GPULib, a tool that simplifies the use of GPUs as mathematical coprocessors from within IDL. mpiDL is unique in its support for the full MPI standard and its support of a broad range of MPI implementations. GPULib is unique in enabling users to take advantage of an inexpensive piece of hardware, possibly already installed in their computer, and achieve orders of magnitude faster execution time for numerically complex algorithms. TaskDL enables the simple setup and management of task farms on compute clusters. The products developed in this project have the

  18. NASA Sun-Earth Connections Theory Program: The Structure and Dynamics of the Solar Corona and Inner Heliosphere

    Science.gov (United States)

    Mikic, Zoran; Grebowsky, Joseph M. (Technical Monitor)

    2001-01-01

    This report covers technical progress during the fourth quarter of the second year of NASA Sun-Earth Connections Theory Program (SECTP) contract 'The Structure and Dynamics of the Solar Corona and Inner Heliosphere,' NAS5-99188, between NASA and Science Applications International Corporation, and covers the period May 16,2001 to August 15, 2001. Under this contract SAIC and the University of California, Irvine (UCI) have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD model.

  19. The effects of oblateness and solar radiation pressure on halo orbits in the photogravitational Sun-Earth system

    Science.gov (United States)

    Srivastava, Vineet K.; Kumar, Jai; Kushvah, Badam Singh

    2016-12-01

    In this paper, we construct a third-order analytic approximate solution using the Lindstedt-Poincare method in the photogravitational circular restricted three body problem considering the Sun as a radiating source and the Earth as an oblate spheroid for computing halo orbits around the collinear Lagrangian points L1 and L2. Further, the well-known differential correction and continuation schemes are used to compute halo orbits and their families numerically. The effects of solar radiation pressure and oblateness on the orbit are studied around both Lagrangian points. From the study, it is noticed that time period of the halo orbit increases around L1 and L2 accounting oblateness of the Earth and solar radiation pressure of the Sun. It is also found that stability of halo orbits is a weak function of the out-of-plane amplitude and mass reduction factor.

  20. Earth-Affecting Solar Causes Observatory (EASCO): A Potential International Living with a Star Mission from Sun-Earth L5

    Science.gov (United States)

    Gopalswamy, N.; Davila, J. M.; St Cyr, O. C.; Sittler, E. C.; Auchere, F.; Duvall, Jr. T. L.; Hoeksema, J. T.; Maksimovic, M.; MacDowall, R. J.; Szabo, A.; Collier, M. R.

    2011-01-01

    This paper describes the scientific rationale for an L5 mission and a partial list of key scientific instruments the mission should carry. The L5 vantage point provides an unprecedented view of the solar disturbances and their solar sources that can greatly advance the science behind space weather. A coronagraph and a heliospheric imager at L5 will be able to view CMEs broadsided, so space speed of the Earth-directed CMEs can be measured accurately and their radial structure discerned. In addition, an inner coronal imager and a magnetograph from L5 can give advance information on active regions and coronal holes that will soon rotate on to the solar disk. Radio remote sensing at low frequencies can provide information on shock-driving CMEs, the most dangerous of all CMEs. Coordinated helioseismic measurements from the Sun Earth line and L5 provide information on the physical conditions at the base of the convection zone, where solar magnetism originates. Finally, in situ measurements at L5 can provide information on the large-scale solar wind structures (corotating interaction regions (CIRs)) heading towards Earth that potentially result in adverse space weather.

  1. 日地系统多物理耦合机制的设计与实现%Design and Implementation of Multi-physics Coupling Mechanism of Sun-Earth System

    Institute of Scientific and Technical Information of China (English)

    李姗姗; 王群

    2011-01-01

    以日地系统活动规律研究为背景,通过对SCIRUN提出的PRMI进行4点改进,提出一种高效的日地系统多物理耦合交互机制PRMI,能够在物理模型组件进行并行远程方法调用实现耦合交互的同时,自动实现网格重映射和数据并行分布重映射.实验结果证明PRMI具有较好的性能.%In the background of study on activity regularity of the sun-earth system, this paper proposes an efficient multi-physics coupling interaction mechanism PRMI++ for sun-earth system based on SCIRUN group's PRMI with four-point improvement. It can automatically accomplish gird re-mapping and parallel distribution re-mapping of data when the physical model components on the parallel remote method invocation to achieve coupling interactions. Experimental results prove PRMI++ has better performance.

  2. A primal-dual interior-point framework for using the L1 or L2 norm on the data and regularization terms of inverse problems

    Science.gov (United States)

    Borsic, A.; Adler, A.

    2012-09-01

    Maximum a posteriori estimates in inverse problems are often based on quadratic formulations, corresponding to a least-squares fitting of the data and to the use of the L2 norm on the regularization term. While the implementation of this estimation is straightforward and usually based on the Gauss-Newton method, resulting estimates are sensitive to outliers and result in spatial distributions of the estimates that are smooth. As an alternative, the use of the L1 norm on the data term renders the estimation robust to outliers, and the use of the L1 norm on the regularization term allows the reconstruction of sharp spatial profiles. The ability therefore to use the L1 norm either on the data term, on the regularization term, or on both is desirable, though the use of this norm results in non-smooth objective functions which require more sophisticated implementations compared to quadratic algorithms. Methods for L1-norm minimization have been studied in a number of contexts, including in the recently popular total variation regularization. Different approaches have been used and methods based on primal-dual interior-point methods (PD-IPMs) have been shown to be particularly efficient. In this paper we derive a PD-IPM framework for using the L1 norm indifferently on the two terms of an inverse problem. We use electrical impedance tomography as an example inverse problem to demonstrate the implementation of the algorithms we derive, and the effect of choosing the L2 or the L1 norm on the two terms of the inverse problem. Pseudo-codes for the algorithms and a public domain implementation are provided.

  3. The Real Reasons for Seasons--Sun-Earth Connections: Unraveling Misconceptions about the Earth and Sun. Grades 6-8. Teacher's Guide. LHS GEMS.

    Science.gov (United States)

    Gould, Alan; Willard, Carolyn; Pompea, Stephen

    This guide is aimed at helping students arrive at a clear understanding of seasons as they investigate the connections between the sun and the earth. Activities include: (1) "Name the Season"; (2) "Sun-Earth Survey"; (3) "Trip to the Sun"; (4) "What Shape is Earth's Orbit?"; (5) "Temperatures around the…

  4. Controlling a transfer trajectory with realistic impulses assumming perturbations in the Sun-Earth-Moon Quasi-Bicircular Problem

    Science.gov (United States)

    Leiva, A. M.; Briozzo, C. B.

    In a previous work we successfully implemented a control algorithm to stabilize unstable periodic orbits in the Sun-Earth-Moon Quasi-Bicircular Problem (QBCP). Applying the same techniques, in this work we stabilize an unstable trajectory performing fast transfers between the Earth and the Moon in a dynamical system similar to the QBCP but incorporating the gravitational perturbation of the planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, assumed to move on circular coplanar heliocentric orbits. In the control stage we used as a reference trajectory an unstable periodic orbit from the unperturbed QBCP. We performed 400 numerical experiments integrating the trajectories over time spans of ~40 years, taking for each one random values for the initial positions of the planets. In all cases the control impulses applied were larger than 20 cm/s, consistently with realistic implementations. The minimal and maximal yearly mean consumptions were ~10 m/s and ~71 m/s, respectively. FULL TEXT IN SPANISH

  5. Optimal design of near-Earth asteroid sample-return trajectories in the Sun-Earth-Moon system

    Science.gov (United States)

    He, Shengmao; Zhu, Zhengfan; Peng, Chao; Ma, Jian; Zhu, Xiaolong; Gao, Yang

    2016-08-01

    In the 6th edition of the Chinese Space Trajectory Design Competition held in 2014, a near-Earth asteroid sample-return trajectory design problem was released, in which the motion of the spacecraft is modeled in multi-body dynamics, considering the gravitational forces of the Sun, Earth, and Moon. It is proposed that an electric-propulsion spacecraft initially parking in a circular 200-km-altitude low Earth orbit is expected to rendezvous with an asteroid and carry as much sample as possible back to the Earth in a 10-year time frame. The team from the Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences has reported a solution with an asteroid sample mass of 328 tons, which is ranked first in the competition. In this article, we will present our design and optimization methods, primarily including overall analysis, target selection, escape from and capture by the Earth-Moon system, and optimization of impulsive and low-thrust trajectories that are modeled in multi-body dynamics. The orbital resonance concept and lunar gravity assists are considered key techniques employed for trajectory design. The reported solution, preliminarily revealing the feasibility of returning a hundreds-of-tons asteroid or asteroid sample, envisions future space missions relating to near-Earth asteroid exploration.

  6. Optimal design of near-Earth asteroid sample-return trajectories in the Sun-Earth-Moon system

    Institute of Scientific and Technical Information of China (English)

    Shengmao He; Zhengfan Zhu; Chao Peng; Jian Ma; Xiaolong Zhu; Yang Gao

    2016-01-01

    In the 6th edition of the Chinese Space Trajec-tory Design Competition held in 2014, a near-Earth asteroid sample-return trajectory design problem was released, in which the motion of the spacecraft is modeled in multi-body dynamics, considering the gravitational forces of the Sun, Earth, and Moon. It is proposed that an electric-propulsion spacecraft initially parking in a circular 200-km-altitude low Earth orbit is expected to rendezvous with an asteroid and carry as much sample as possible back to the Earth in a 10-year time frame. The team from the Technology and Engi-neering Center for Space Utilization, Chinese Academy of Sciences has reported a solution with an asteroid sample mass of 328 tons, which is ranked first in the competition. In this article, we will present our design and optimization methods, primarily including overall analysis, target selec-tion, escape from and capture by the Earth–Moon system, and optimization of impulsive and low-thrust trajectories that are modeled in multi-body dynamics. The orbital res-onance concept and lunar gravity assists are considered key techniques employed for trajectory design. The reported solution, preliminarily revealing the feasibility of returning a hundreds-of-tons asteroid or asteroid sample, envisions future space missions relating to near-Earth asteroid explo-ration.

  7. The Spanish Space Weather Service SeNMEs. A Case Study on the Sun-Earth Chain

    Science.gov (United States)

    Palacios, J.; Cid, C.; Guerrero, A.; Saiz, E.; Cerrato, Y.; Rodríguez-Bouza, M.; Rodríguez-Bilbao, I.; Herraiz, M.; Rodríguez-Caderot, G.

    2016-04-01

    The Spanish Space Weather Service SeNMEs, www.senmes.es, is a portal created by the SRG-SW of the Universidad de Alcalá, Spain, to meet societal needs of near real-time space weather services. This webpage-portal is divided in different sections to fulfill users needs about space weather effects: radio blackouts, solar energetic particle events, geomagnetic storms and presence of geomagnetically induced currents. In less than one year of activity, this service has released a daily report concerning the solar current status and interplanetary medium, informing about the chances of a solar perturbation to hit the Earth's environment. There are also two different forecasting tools for geomagnetic storms, and a daily ionospheric map. These tools allow us to nowcast a variety of solar eruptive events and forecast geomagnetic storms and their recovery, including a new local geomagnetic index, LDiñ, along with some specific new scaling. In this paper we also include a case study analysed by SeNMEs. Using different high resolution and cadence data from space-borne solar telescopes SDO, SOHO and GOES, along with ionospheric and geomagnetic data, we describe the Sun-Earth feature chain for the event.

  8. Restoration and Archiving of Data from the Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE 1)

    Science.gov (United States)

    Lennartsson, O. W.

    1997-01-01

    The objective of this project has been to complete the archiving of energetic (10 eV/epsilon - 18 keV/epsilon) ion composition data from the Lockheed Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE 1) satellite, using a particular data format that had previously been approved by NASA and the NSSDC. That same format, a combination of ion velocity moments and differential flux spectra, had been used in 1991 to archive, at the NSSDC, the first 28 months (the "Prime" period of ISEE investigations) of data from the Lockheed instrument under NASA Contract NAS5-33047. With the completion of this project, the almost 4 1/2-year time span of these unique data is now covered by a very compact set, approximately 1 gigabyte in total, of electronic files with physical quantities, all in ASCII. The files are organized by data type and time of data acquisition, in Universal Time, and named according to year and day of year. Each calendar day has five separate files (five types of data), the lengths of which vary from day to day, depending on the instrument mode of operation. The data format and file structure are described in detail in appendices 1 and 2. The physical medium consists of high-density (6250 cpi) 9-track magnetic tapes, complemented by a set of hardcopy line plots of certain plasma parameters. In this case there are five tapes, to be added to the six previous ones from 1991, and 25 booklets of plots, one per month, to be added to the previous 28. The tapes, including an extra standard-density (1600 cpi) tape with electronic versions of the Data User's Guide and self-guiding VAX/VMS command files, and the hardcopy plots are being boxed for shipment to the NSSDC.

  9. Restoration and Archiving of Data from the Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE 1)

    Science.gov (United States)

    Lennartsson, O. W.

    1997-08-01

    The objective of this project has been to complete the archiving of energetic (10 eV/epsilon - 18 keV/epsilon) ion composition data from the Lockheed Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE 1) satellite, using a particular data format that had previously been approved by NASA and the NSSDC. That same format, a combination of ion velocity moments and differential flux spectra, had been used in 1991 to archive, at the NSSDC, the first 28 months (the "Prime" period of ISEE investigations) of data from the Lockheed instrument under NASA Contract NAS5-33047. With the completion of this project, the almost 4 1/2-year time span of these unique data is now covered by a very compact set, approximately 1 gigabyte in total, of electronic files with physical quantities, all in ASCII. The files are organized by data type and time of data acquisition, in Universal Time, and named according to year and day of year. Each calendar day has five separate files (five types of data), the lengths of which vary from day to day, depending on the instrument mode of operation. The data format and file structure are described in detail in appendices 1 and 2. The physical medium consists of high-density (6250 cpi) 9-track magnetic tapes, complemented by a set of hardcopy line plots of certain plasma parameters. In this case there are five tapes, to be added to the six previous ones from 1991, and 25 booklets of plots, one per month, to be added to the previous 28. The tapes, including an extra standard-density (1600 cpi) tape with electronic versions of the Data User's Guide and self-guiding VAX/VMS command files, and the hardcopy plots are being boxed for shipment to the NSSDC.

  10. Improving solar wind persistence forecasts: Removing transient space weather events, and using observations away from the Sun-Earth line

    Science.gov (United States)

    Kohutova, Petra; Bocquet, François-Xavier; Henley, Edmund M.; Owens, Matthew J.

    2016-10-01

    This study demonstrates two significant ways of improving persistence forecasts of the solar wind, which exploit the relatively unchanging nature of the ambient solar wind to provide 27 day forecasts, when using data from the Lagrangian L1 point. Such forecasts are useful as a prediction tool for the ambient wind, and for benchmarking of solar wind models. We show that solar wind persistence forecasts can be improved by removing transient solar wind features such as coronal mass ejections (CMEs). Using CME indicators to automatically identify CME-contaminated periods in ACE data from 1998 to 2011, and replacing these with solar wind from a previous synodic rotation, persistence forecasts improve (relative to a baseline): skill scores for Bz, a crucial parameter for determining solar wind geoeffectiveness, improve by 7.7 percentage points when using a proton temperature-based indicator with good operational potential. We also show that persistence forecasts can be improved by using measurements away from L1, to reduce the requirement on coronal stability for an entire synodic period, at the cost of reduced lead time. Using STEREO-B data from 2007 to 2013 to create such a reduced lead time persistence forecast, we show that Bz skill scores improve by 17.1 percentage points relative to ACE. Finally, we report on implications for persistence forecasts from any future missions to the L5 Lagrangian point and on the successful operational implementation (in spring 2015) of the normal (ACE-based) and reduced lead time (STEREO-based) persistence forecasts in the Met Office's Space Weather Operations Centre, as well as plans for future improvements.

  11. A Full Study on the Sun-Earth Connection of an Earth-Directed CME Magnetic Flux Rope

    CERN Document Server

    Vemareddy, P

    2015-01-01

    We present an investigation of an eruption event of coronal mass ejection (CME) magnetic flux rope (MFR) from source active region (AR) NOAA 11719 on 11 April 2013 utilizing observations from SDO, STEREO, SOHO, and WIND spacecraft. The source AR consists of pre-existing sigmoidal structure stacked over a filament channel which is regarded as MFR system. EUV observations of low corona suggest a further development of this MFR system by added axial flux through tether-cutting reconnection of loops at the middle of sigmoid under the influence of continuous slow flux motions during past two days. Our study implies that the MFR system in the AR is initiated to upward motion by kink-instability and further driven by torus-instability. The CME morphology, captured in simultaneous three-point coronagraph observations, is fitted with Graduated Cylindrical Shell (GCS) model and discerns an MFR topology with orientation aligning with magnetic neutral line in the source AR. This MFR expands self-similarly and is found to...

  12. L2 listening at work

    DEFF Research Database (Denmark)

    Øhrstrøm, Charlotte

    This dissertation on adult second language (L2) learning investigates individual learners’ experiences with listening in Danish as an L2 in everyday situations at work. More specifically, the study explores when international employees, who work at international companies in Denmark with English ...... oriented approaches within the research field of Second Language Acquisition (SLA)....

  13. Representation and Embodiment of Meaning in L2 Communication: Motion Events in the Speech and Gesture of Advanced L2 Korean and L2 English Speakers

    Science.gov (United States)

    Choi, Soojung; Lantolf, James P.

    2008-01-01

    This study investigates the interface between speech and gesture in second language (L2) narration within Slobin's (2003) thinking-for-speaking (TFS) framework as well as with respect to McNeill's (1992, 2005) growth point (GP) hypothesis. Specifically, our interest is in whether speakers shift from a first language (L1) to a L2 TFS pattern as…

  14. L2 listening at work

    DEFF Research Database (Denmark)

    Øhrstrøm, Charlotte

    This dissertation on adult second language (L2) learning investigates individual learners’ experiences with listening in Danish as an L2 in everyday situations at work. More specifically, the study explores when international employees, who work at international companies in Denmark with English...... as a corporate language, listen in Danish at work, how they handle these situations, what problems they experience, and why some situations are more difficult to listen in than others. The study makes use of qualitative research methods and theoretical aspects from psycholinguistic approaches as well as socially...

  15. Adaptive surrogate model based multi-objective transfer trajectory optimization between different libration points

    Science.gov (United States)

    Peng, Haijun; Wang, Wei

    2016-10-01

    An adaptive surrogate model-based multi-objective optimization strategy that combines the benefits of invariant manifolds and low-thrust control toward developing a low-computational-cost transfer trajectory between libration orbits around the L1 and L2 libration points in the Sun-Earth system has been proposed in this paper. A new structure for a multi-objective transfer trajectory optimization model that divides the transfer trajectory into several segments and gives the dominations for invariant manifolds and low-thrust control in different segments has been established. To reduce the computational cost of multi-objective transfer trajectory optimization, a mixed sampling strategy-based adaptive surrogate model has been proposed. Numerical simulations show that the results obtained from the adaptive surrogate-based multi-objective optimization are in agreement with the results obtained using direct multi-objective optimization methods, and the computational workload of the adaptive surrogate-based multi-objective optimization is only approximately 10% of that of direct multi-objective optimization. Furthermore, the generating efficiency of the Pareto points of the adaptive surrogate-based multi-objective optimization is approximately 8 times that of the direct multi-objective optimization. Therefore, the proposed adaptive surrogate-based multi-objective optimization provides obvious advantages over direct multi-objective optimization methods.

  16. Noticing in L2 writing

    OpenAIRE

    Geist, Monika

    2013-01-01

    The study investigated the ways L2 learners of English reflect on their use of English while completing a writing task and the strategies learners apply in order to resolve their language-related problems. Factors which might have some influence on the learners' noticing and problem-solving behaviour were explored using a qualitative, inductive research approach involving the detailed analyses of ten participants. Think-aloud protocols and stimulated recall interviews were used to investigate...

  17. Testing the Strong Equivalence Principle with spacecraft ranging towards the nearby Lagrangian points

    CERN Document Server

    Congedo, Giuseppe

    2016-01-01

    General relativity is supported by great experimental evidence. Yet there is a lot of interest in precisely setting its limits with on going and future experiments. A question to answer is about the validity of the Strong Equivalence Principle. Ground experiments and Lunar Laser Ranging have provided the best upper limit on the Nordtvedt parameter $\\sigma[\\eta]=4.4\\times 10^{-4}$. With the future planetary mission BepiColombo, this parameter will be further improved by at least an order of magnitude. In this paper we envisage yet another possible testing environment with spacecraft ranging towards the nearby Sun-Earth collinear Lagrangian points. Neglecting errors in planetary masses and ephemerides, we forecast $\\sigma[\\eta]=6.4\\text{-}2.0\\times10^{-4}$ (5 yr integration time) via ranging towards $L_1$ in realistic and optimistic scenarios depending on current and future range capabilities and knowledge of the Earth's ephemerides. A combined measurement, $L_1$+$L_2$, gives instead $4.8\\text{-}1.7\\times10^{-4...

  18. On the effects of L2 perception and of individual differences in L1 production on L2 pronunciation

    Science.gov (United States)

    Kartushina, Natalia; Frauenfelder, Ulrich H.

    2014-01-01

    The speech of late second language (L2) learners is generally marked by an accent. The dominant theoretical perspective attributes accents to deficient L2 perception arising from a transfer of L1 phonology, which is thought to influence L2 perception and production. In this study we evaluate the explanatory role of L2 perception in L2 production and explore alternative explanations arising from the L1 phonological system, such as for example, the role of L1 production. Specifically we examine the role of an individual’s L1 productions in the production of L2 vowel contrasts. Fourteen Spanish adolescents studying French at school were assessed on their perception and production of the mid-close/mid-open contrasts, /ø-œ/ and /e-ε/, which are, respectively, acoustically distinct from Spanish sounds, or similar to them. The participants’ native productions were explored to assess (1) the variability in the production of native vowels (i.e., the compactness of vowel categories in F1/F2 acoustic space), and (2) the position of the vowels in the acoustic space. The results revealed that although poorly perceived contrasts were generally produced poorly, there was no correlation between individual performance in perception and production, and no effect of L2 perception on L2 production in mixed-effects regression analyses. This result is consistent with a growing body of psycholinguistic and neuroimaging research that suggest partial dissociations between L2 perception and production. In contrast, individual differences in the compactness and position of native vowels predicted L2 production accuracy. These results point to existence of surface transfer of individual L1 phonetic realizations to L2 space and demonstrate that pre-existing features of the native space in production partly determine how new sounds can be accommodated in that space. PMID:25414678

  19. On the effects of L2 perception and of individual differences in L1 production on L2 pronunciation.

    Science.gov (United States)

    Kartushina, Natalia; Frauenfelder, Ulrich H

    2014-01-01

    The speech of late second language (L2) learners is generally marked by an accent. The dominant theoretical perspective attributes accents to deficient L2 perception arising from a transfer of L1 phonology, which is thought to influence L2 perception and production. In this study we evaluate the explanatory role of L2 perception in L2 production and explore alternative explanations arising from the L1 phonological system, such as for example, the role of L1 production. Specifically we examine the role of an individual's L1 productions in the production of L2 vowel contrasts. Fourteen Spanish adolescents studying French at school were assessed on their perception and production of the mid-close/mid-open contrasts, /ø-œ/ and /e-ε/, which are, respectively, acoustically distinct from Spanish sounds, or similar to them. The participants' native productions were explored to assess (1) the variability in the production of native vowels (i.e., the compactness of vowel categories in F1/F2 acoustic space), and (2) the position of the vowels in the acoustic space. The results revealed that although poorly perceived contrasts were generally produced poorly, there was no correlation between individual performance in perception and production, and no effect of L2 perception on L2 production in mixed-effects regression analyses. This result is consistent with a growing body of psycholinguistic and neuroimaging research that suggest partial dissociations between L2 perception and production. In contrast, individual differences in the compactness and position of native vowels predicted L2 production accuracy. These results point to existence of surface transfer of individual L1 phonetic realizations to L2 space and demonstrate that pre-existing features of the native space in production partly determine how new sounds can be accommodated in that space.

  20. On the effects of L2 perception and of individual differences in L1 production on L2 pronunciation

    Directory of Open Access Journals (Sweden)

    Natalia eKartushina

    2014-11-01

    Full Text Available The speech of late second language (L2 learners is generally marked by an accent. The dominant theoretical perspective attributes accents to deficient L2 perception arising from a transfer of L1 phonology, which is thought to influence L2 perception and production. In this study we evaluate the explanatory role of L2 perception in L2 production and explore alternative explanations arising from the L1 phonological system, such as for example, the role of L1 production. Specifically we examine the role of an individual’s L1 productions in the production of L2 vowel contrasts. Fourteen Spanish adolescents studying French at school were assessed on their perception and production of the mid-close/mid-open contrasts, /ø-œ/ and /e-ε/, which are, respectively, acoustically distinct from Spanish sounds, or similar to them. The participants’ native productions were explored to assess 1 the variability in the production of native vowels (i.e., the compactness of vowel categories in F1/F2 acoustic space, and 2 the position of the vowels in the acoustic space. The results revealed that although poorly perceived contrasts were generally produced poorly, there was no correlation between individual performance in perception and production, and no effect of L2 perception on L2 production in mixed-effects regression analyses. This result is consistent with a growing body of psycholinguistic and neuroimaging research that suggest partial dissociations between L2 perception and production. In contrast, individual differences in the compactness and position of native vowels predicted L2 production accuracy. These results point to existence of surface transfer of individual L1 phonetic realisations to L2 space and demonstrate that pre-existing features of the native space in production partly determine how new sounds can be accommodated in that space.

  1. Existence and Stability the Lagrangian point $L_4$ for the Earth-Sun system under a relativistic framework

    CERN Document Server

    Perdomo, Oscar M

    2016-01-01

    It is well known that, from the Newtonian point of view, the Lagrangian point $L_4$ in the circular restricted three body is stable if $\\mu< \\frac{1}{18}(9-\\sqrt{19})\\approx 0.03852$. In this paper we will provide a formula that allows us to compute the eigenvalues of the matrix that determines the stability of the equilibrium points of a family of ordinary differential equations. As an application we will show that, under the relativistic framework, the Lagrangian point $L_4$ is also stable for the Sun-Earth system. Similar arguments show the stability for $L_4$ not only for the Sun-Earth system but for systems coming from a range of values for $\\mu$ similar to those in the Newtonian restricted three body problem.

  2. The Acquisition of L2 Phonology

    Science.gov (United States)

    Wojtaszek, Adam; Arabski, Janusz

    2011-01-01

    The Acquisition of L2 Phonology is a wide-ranging new collection which focuses on various aspects of the acquisition of an L2 phonological system. The authors are researchers and practitioners from five different countries. The volume has been divided into three major sections. Phonetic Analysis presents five studies of language learners in both…

  3. The Acquisition of L2 Phonology

    Science.gov (United States)

    Wojtaszek, Adam; Arabski, Janusz

    2011-01-01

    The Acquisition of L2 Phonology is a wide-ranging new collection which focuses on various aspects of the acquisition of an L2 phonological system. The authors are researchers and practitioners from five different countries. The volume has been divided into three major sections. Phonetic Analysis presents five studies of language learners in both…

  4. Defining and Operationalising L2 Complexity

    Science.gov (United States)

    Bulte, Bram; Housen, Alex

    2012-01-01

    This chapter takes a critical look at complexity in L2 research. We demonstrate several problems in the L2 literature in terms of how complexity has been defined and operationalised as a construct. In the first part of the chapter we try to unravel its highly complex, multidimensional nature by presenting a taxonomic model that identifies major…

  5. Access to Mars from Earth-Moon Libration Point Orbits:. [Manifold and Direct Options

    Science.gov (United States)

    Kakoi, Masaki; Howell, Kathleen C.; Folta, David

    2014-01-01

    This investigation is focused specifically on transfers from Earth-Moon L(sub 1)/L(sub 2) libration point orbits to Mars. Initially, the analysis is based in the circular restricted three-body problem to utilize the framework of the invariant manifolds. Various departure scenarios are compared, including arcs that leverage manifolds associated with the Sun-Earth L(sub 2) orbits as well as non-manifold trajectories. For the manifold options, ballistic transfers from Earth-Moon L(sub 2) libration point orbits to Sun-Earth L(sub 1)/L(sub 2) halo orbits are first computed. This autonomous procedure applies to both departure and arrival between the Earth-Moon and Sun-Earth systems. Departure times in the lunar cycle, amplitudes and types of libration point orbits, manifold selection, and the orientation/location of the surface of section all contribute to produce a variety of options. As the destination planet, the ephemeris position for Mars is employed throughout the analysis. The complete transfer is transitioned to the ephemeris model after the initial design phase. Results for multiple departure/arrival scenarios are compared.

  6. A Key Factor Affecting L2 (English) Vocabulary Acquisition:L2 (English) Proficiency

    Institute of Scientific and Technical Information of China (English)

    周祁林

    2014-01-01

    There are some certain factors affecting L2 ( English) vocabulary acquisition such as L2 ( English) proficiency, readers’ purpose and the habit of reading, and the difficulty of target words and context, among which the first plays a key role. The paper, through a review of the relevant experimental researches, reaches a conclusion that L2 ( English) proficiency does influence much upon L2 vocabulary acquisition.

  7. The L2 Motivational Self System and L2 Achievement: A Study of Saudi EFL Learners

    Science.gov (United States)

    Moskovsky, Christo; Assulaimani, Turki; Racheva, Silvia; Harkins, Jean

    2016-01-01

    The research reported in this article explores the relationship between Dörnyei's (2005, 2009) Second Language Motivational Self System (L2MSS) and the L2 proficiency level of Saudi learners of English as a foreign language (EFL). Male and female participants (N = 360) responded to a questionnaire relating to the main components of L2MSS, the…

  8. Using Eye-Tracking to Investigate Topics in L2 Acquisition and L2 Processing

    Science.gov (United States)

    Roberts, Leah; Siyanova-Chanturia, Anna

    2013-01-01

    Second language (L2) researchers are becoming more interested in both L2 learners' knowledge of the target language and how that knowledge is put to use during real-time language processing. Researchers are therefore beginning to see the importance of combining traditional L2 research methods with those that capture the moment-by-moment…

  9. Review of L2 Vocabulary Acquisition Studies

    Institute of Scientific and Technical Information of China (English)

    周先军

    2014-01-01

    Vocabulary is important in language and language acquisition, but it did not catch as much attention as it deserved for a long time. In this thesis, I’ll go through changes of vocabulary studied in linguistics and language teaching as well as rise of L2 vocabulary acquisition studies. Several aspects of L2 vocabulary acquisition studies will then be reviewed.Issues that need to be further studied will at last be put forward.

  10. Review of L2 Vocabulary Acquisition Studies

    Institute of Scientific and Technical Information of China (English)

    周先军

    2014-01-01

    Vocabulary is important in language and language acquisition, but it did not catch as much attention as it deserved for a long time. In this thesis, I’ll go through changes of vocabulary studied in linguistics and language teaching as well as rise of L2 vocabulary acquisition studies. Several aspects of L2 vocabulary acquisition studies will then be reviewed .Issues that need to be further studied will at last be put forward.

  11. Lexical representation of novel L2 contrasts

    Science.gov (United States)

    Hayes-Harb, Rachel; Masuda, Kyoko

    2005-04-01

    There is much interest among psychologists and linguists in the influence of the native language sound system on the acquisition of second languages (Best, 1995; Flege, 1995). Most studies of second language (L2) speech focus on how learners perceive and produce L2 sounds, but we know of only two that have considered how novel sound contrasts are encoded in learners' lexical representations of L2 words (Pallier et al., 2001; Ota et al., 2002). In this study we investigated how native speakers of English encode Japanese consonant quantity contrasts in their developing Japanese lexicons at different stages of acquisition (Japanese contrasts singleton versus geminate consonants but English does not). Monolingual English speakers, native English speakers learning Japanese for one year, and native speakers of Japanese were taught a set of Japanese nonwords containing singleton and geminate consonants. Subjects then performed memory tasks eliciting perception and production data to determine whether they encoded the Japanese consonant quantity contrast lexically. Overall accuracy in these tasks was a function of Japanese language experience, and acoustic analysis of the production data revealed non-native-like patterns of differentiation of singleton and geminate consonants among the L2 learners of Japanese. Implications for theories of L2 speech are discussed.

  12. Suggestions of keeping L2 motivation

    Institute of Scientific and Technical Information of China (English)

    徐斌

    2014-01-01

    How will we keep the motivation during the second language as long as we can, which confuses us, though what the L2 motivation is and how it is developed have been discussed by the psychologists, educators, etc. The aim of this passage is to clarify the basic content of motivation, including the definition, classification, importance, etc. how the current situation is in se-nior high students’English learning motivation, what should be done to keep such motivation. In the following part, it will be read that the introduction, the chapter stating the content and classification of (L 2) motivation, the chapter analyzing the necessity and state of L2 motivation at senor high, the chapter offering approach to keep that motivation, and the conclusion. All of them use the comparison, explanation and cites.

  13. L-2-hydroxyglutaric aciduria: A case report

    Directory of Open Access Journals (Sweden)

    Jović Nebojša J.

    2014-01-01

    Full Text Available Introduction. L-2-Hydroxyglutaric aciduria (L-2-HGA is an autosomal recessive neurometabolic disease with a slowly progressive course and characterized by increased levels of hydroxyglutaric acid in urine, cerebrospinal fluid and plasma. In this condition clinical features mainly consist of mental deterioration, ataxia and motor deficits. Case Outline. The patient is a 16-year-old girl, the first and only child of healthy, non-consanguineous parents of Serbian origin. At the age of 4 years her walk became unsteady and ataxic. Other signs of cerebellar involvement were soon observed. Head circumference was above two standard deviations (55 cm. Mild mental retardation was revealed by formal intelligence testing (IQ 60. MR examination of the brain showed confluent subcortical white matter lesions spread centripetally, and atrophy of the cerebellar vermis with involvement of dentate nuclei, without deep white matter abnormalities. Laboratory investigation revealed increased amounts and a very large peak of HGA in urine and plasma. Enantiomeric analysis confirmed the L-configuration (>90% establishing the diagnosis of L-2-HGA. The first epileptic seizure, partial with secondary generalization, occurred at age of 8 years. Favorable seizure control was achieved. A slow progression of neurological impairment was noted. Therapeutic trials with oral coenzyme Q10 and with oral riboflavin showed no biochemical and clinical effects. Recently, the diagnosis was proven by the presence of a mutation in the L-2-HGA gene. Conclusion. To our knowledge, this is the first report of L-2-HGA in Serbia. L-2-HGA must be considered in the differential diagnosis based on specific findings in cranial MRI.

  14. L^2-Betti numbers of hypersurface complements

    CERN Document Server

    Maxim, Laurentiu

    2012-01-01

    In \\cite{DJL07} it was shown that if $\\scra$ is an affine hyperplane arrangement in $\\C^n$, then at most one of the $L^2$--Betti numbers $b_i^{(2)}(\\C^n\\sm \\scra,\\id)$ is non--zero. In this note we prove an analogous statement for complements of complex affine hyperurfaces in general position at infinity. Furthermore, we recast and extend to this higher-dimensional setting results of \\cite{FLM,LM06} about $L^2$--Betti numbers of plane curve complements.

  15. Selective Teaching of L2 Pronunciation

    Science.gov (United States)

    Husby, Olaf; Koreman, Jacques; Martínez-Paricio, Violeta; Abrahamsen, Jardar E.; Albertsen, Egil; Hedayatfar, Keivan; Bech, Øyvind

    2015-01-01

    The pronunciation of a second or foreign language is often very challenging for L2 learners. It is difficult to address this topic in the classroom, because learners with different native languages (L1s) can have very different challenges. We have therefore developed a Computer-Assisted Listening and Speaking Tutor (CALST), which selectively…

  16. L2 Writing Conferences: Investigating Teacher Talk

    Science.gov (United States)

    Ewert, Doreen E.

    2009-01-01

    Although the role of social interaction through conversational activities is well established in the L2 writing classroom in relation to idea development, understanding rhetorical modes, the creation of a sense of audience, as well as the promotion of feedback, relatively little attention has been given to the actual discourse of teachers and…

  17. Hyperbolic L2-modules with Reproducing Kernels

    Institute of Scientific and Technical Information of China (English)

    David EELPODE; Frank SOMMEN

    2006-01-01

    Abstract In this paper, the Dirac operator on the Klein model for the hyperbolic space is considered. A function space containing L2-functions on the sphere Sm-1 in (R)m, which are boundary values of solutions for this operator, is defined, and it is proved that this gives rise to a Hilbert module with a reproducing kernel.

  18. Phonological bases for L2 morphological learning.

    Science.gov (United States)

    Hu, Chieh-Fang

    2010-08-01

    Two experiments examined the hypothesis that L1 phonological awareness plays a role in children's ability to extract morphological patterns of English as L2 from the auditory input. In Experiment 1, 84 Chinese-speaking third graders were tested on whether they extracted the alternation pattern between the base and the derived form (e.g., inflate - inflation) from multiple exposures. Experiment 2 further assessed children's ability to use morphological cues for syntactic categorization through exposures to novel morphologically varying forms (e.g., lutate vs. lutant) presented in the corresponding sentential positions (noun vs. verb). The third-grade EFL learners revealed emergent sensitivity to the morphological cues in the input but failed in fully processing intraword variations. The learners with poorer L1 PA were likely to encounter difficulties in identifying morphological alternation rules and in discovering the syntactic properties of L2 morphology. In addition to L1 PA, L2 vocabulary knowledge also contributed significantly to L2 morphological learning.

  19. Investigating L2 Performance in Text Chat

    Science.gov (United States)

    Sauro, Shannon; Smith, Bryan

    2010-01-01

    This study examines the linguistic complexity and lexical diversity of both overt and covert L2 output produced during synchronous written computer-mediated communication, also referred to as chat. Video enhanced chatscripts produced by university learners of German (N = 23) engaged in dyadic task-based chat interaction were coded and analyzed for…

  20. L2 Chinese: Grammatical Development and Processing

    Science.gov (United States)

    Mai, Ziyin

    2016-01-01

    Two recent books (Jiang, 2014, "Advances in Chinese as a second language"; Wang, 2013, "Grammatical development of Chinese among non-native speakers") provide new resources for exploring the role of processing in acquiring Chinese as a second language (L2). This review article summarizes, assesses and compares some of the…

  1. Repair Negotiation by English L2 Learners

    Science.gov (United States)

    Choi, Yujeong

    2012-01-01

    It is widely accepted that L2 learners often face communication problems due to lack of competency in the target language and familiarity with its culture of origin. One way to resolve miscommunication problems is to seek clarification of the utterance; this process is called "repair negotiation" (Nakahama et al. 2001). Repair…

  2. Irregular wavelet frames on L2(Rn)

    Institute of Scientific and Technical Information of China (English)

    YANG Deyun; ZHOU Xingwei

    2005-01-01

    In this paper, we present the conditions on dilation parameter {sj }j that ensure a discrete irregular wavelet system {Snj/2ψ(sj·-bk)}j∈(Z),k∈(Z)n to be a frame on L2(Rn),and for the wavelet frame we consider the perturbations of translation parameter b and frame function ψ respectively.

  3. Voice Blogging and L2 Speaking Performance

    Science.gov (United States)

    Hsu, Hsiu-Chen

    2016-01-01

    This paper reports on an exploratory study that investigated the effect of extensive speaking practice on the development of L2 speaking complexity, accuracy, and fluency in voice blogging. The participants were 30 college EFL (English as a foreign language) learners in Taiwan. As a supplement to the insufficient speaking practice in class, each…

  4. Using Conventional Sequences in L2 French

    Science.gov (United States)

    Forsberg, Fanny

    2010-01-01

    By means of a phraseological identification method, this study provides a general description of the use of conventional sequences (CSs) in interviews at four different levels of spoken L2 French as well as in interviews with native speakers. Use of conventional sequences is studied with regard to overall quantity, category distribution and type…

  5. L’ACQUISIZIONE DEI SEGNALI DISCORSIVI IN ITALIANO L2

    Directory of Open Access Journals (Sweden)

    Elisabetta Jafrancesco

    2015-07-01

    analyzed the use of SD in the spoken dialogue between students at the basic, independent and competent CEFR levels, with reference to the taxonomic SD model proposed by Bazzanella in the Grande grammatica italiana di consultazione (1995. In relation to the specific context, we integrated new features, focusing on key macro-phenomena that emerged, with the intention of considering how L2 data acquisition can be a reference point for the definition of training consistent with the natural processes of competence development.

  6. Preparing an L2 Role-Play: How Students Manage L2 Deficits

    Science.gov (United States)

    Edstrom, Anne

    2013-01-01

    There is considerable variation in the implementation of role-play activities in second language (L2)/foreign language (FL) classroom settings, and little information is available about how students actually manage them, particularly with regards to overcoming their L2 deficits. This study examines the preparation of role-plays by university…

  7. Phonological Substitution Errors in L2 ASL Sentence Processing by Hearing M2L2 Learners

    Science.gov (United States)

    Williams, Joshua; Newman, Sharlene

    2016-01-01

    In the present study we aimed to investigate phonological substitution errors made by hearing second language (M2L2) learners of American Sign Language (ASL) during a sentence translation task. Learners saw sentences in ASL that were signed by either a native signer or a M2L2 learner. Learners were to simply translate the sentence from ASL to…

  8. The Effects of L1 and L2 Group Discussions on L2 Reading Comprehension

    Science.gov (United States)

    Turnbull, Blake; Evans, Moyra Sweetnam

    2017-01-01

    The aim of this study was to explore the effects of post-reading group discussions in both first (L1) and second (L2) languages on L2 reading comprehension. The participants were fifteen Japanese university students of intermediate-level English. Three cohorts read four English texts and produced individual written recalls. Group 1 (the control…

  9. The Impact of Resilience on L2 Learners' Motivated Behaviour and Proficiency in L2 Learning

    Science.gov (United States)

    Kim, Tae-Young; Kim, Yoon-Kyoung

    2017-01-01

    This exploratory study focused on the factors that constitute second language (L2) learners' resilience, and how these factors are related to L2 learning by investigating what relation resilience may have to motivated behaviour and proficiency in English learning. A total of 1620 secondary school learners of English participated in a questionnaire…

  10. The Impact of Resilience on L2 Learners' Motivated Behaviour and Proficiency in L2 Learning

    Science.gov (United States)

    Kim, Tae-Young; Kim, Yoon-Kyoung

    2017-01-01

    This exploratory study focused on the factors that constitute second language (L2) learners' resilience, and how these factors are related to L2 learning by investigating what relation resilience may have to motivated behaviour and proficiency in English learning. A total of 1620 secondary school learners of English participated in a questionnaire…

  11. Processing Focus Structure in L1 and L2 French: L2 Proficiency Effects on ERPs

    Science.gov (United States)

    Reichle, Robert V.; Birdsong, David

    2014-01-01

    This study examined the event-related potentials (ERPs) elicited by focus processing among first language (L1) speakers and second language (L2) learners of French. Participants read wh-questions containing explicit focus marking, followed by responses instantiating contrastive and informational focus. We hypothesized that L2 proficiency would…

  12. Semantic Representation of Newly Learned L2 Words and Their Integration in the L2 Lexicon

    Science.gov (United States)

    Bordag, Denisa; Kirschenbaum, Amit; Rogahn, Maria; Opitz, Andreas

    2017-01-01

    The present semantic priming study explores the integration of newly learnt L2 German words into the L2 semantic network of German advanced learners. It provides additional evidence in support of earlier findings reporting semantic inhibition effects for emergent representations. An inhibitory mechanism is proposed that temporarily decreases the…

  13. Development and implementation of a novel assay for L-2-hydroxyglutarate dehydrogenase (L-2-HGDH) in cell lysates: L-2-HGDH deficiency in 15 patients with L-2-hydroxyglutaric aciduria

    DEFF Research Database (Denmark)

    Kranendijk, M; Salomons, G S; Gibson, K M

    2009-01-01

    L-2-hydroxyglutaric aciduria (L-2-HGA) is a rare inherited autosomal recessive neurometabolic disorder caused by mutations in the gene encoding L-2-hydroxyglutarate dehydrogenase. An assay to evaluate L-2-hydroxyglutarate dehydrogenase (L-2-HGDH) activity in fibroblast, lymphoblast and/or lymphoc...

  14. How L2 words are stored: the episodic L2 hypothesis.

    Science.gov (United States)

    Witzel, Naoko Ouchi; Forster, Kenneth I

    2012-11-01

    This article reports findings from 3 experiments examining whether 2nd language (L2) words are represented in episodic memory, as originally proposed by Jiang and Forster (2001). Experiment 1 was a direct replication of Jiang and Forster, testing highly proficient Chinese-English bilinguals. Masked translation priming was obtained in an episodic recognition task from L2 to the 1st language (L1) for studied "old" L1 targets but not for unstudied "new" targets. This experiment also confirmed the translation asymmetry generally found in lexical decision tasks, namely, priming in the L1-L2 direction but not in the L2-L1 direction. Experiment 2 showed that recently learned words in an unfamiliar language (therefore, words that are obviously represented episodically) could also prime their L1 translations in an episodic recognition task but not in a lexical decision task. Finally, in Experiment 3, masked repetition priming was used with an episodic recognition memory task. For native speakers of English, repetition (L1-L1) priming is obtained only for old words, because there is no episodic representation for new words. However, Chinese-English bilinguals tested with the same items showed repetition (L2-L2) priming for both old and new words, indicating that the new L2 words were represented episodically as well. Overall, the results from these 3 experiments support the hypothesis that L2 words are represented in episodic memory. Finally, the mechanisms behind why L2-L1 translation priming can be obtained in episodic recognition and not in lexical decision are discussed.

  15. COMPUTING THE VOCABULARY DEMANDS OF L2 READING

    Directory of Open Access Journals (Sweden)

    Tom Cobb

    2007-02-01

    Full Text Available Linguistic computing can make two important contributions to second language (L2 reading instruction. One is to resolve longstanding research issues that are based on an insufficiency of data for the researcher, and the other is to resolve related pedagogical problems based on insufficiency of input for the learner. The research section of the paper addresses the question of whether reading alone can give learners enough vocabulary to read. When the computer’s ability to process large amounts of both learner and linguistic data is applied to this question, it becomes clear that, for the vast majority of L2 learners, free or wide reading alone is not a sufficient source of vocabulary knowledge for reading. But computer processing also points to solutions to this problem. Through its ability to reorganize and link documents, the networked computer can increase the supply of vocabulary input that is available to the learner. The development section of the paper elaborates a principled role for computing in L2 reading pedagogy, with examples, in two broad areas, computer-based text design and computational enrichment of undesigned texts.

  16. The Application of L2TP VPN%L2TP VPN的应用

    Institute of Scientific and Technical Information of China (English)

    宁云亭

    2009-01-01

    介绍了虚拟专用网络的产生背景、实现方式、性能特点.重点介绍了L2TP VPN与IPsec VPN虚拟专用网络,比较了构成特点和适用对象,给出了构建L2TP VPN网络实例.

  17. Orthogonal Multiwavelet Frames in L2Rd

    Directory of Open Access Journals (Sweden)

    Liu Zhanwei

    2012-01-01

    Full Text Available We characterize the orthogonal frames and orthogonal multiwavelet frames in L2Rd with matrix dilations of the form (Df(x=detAf(Ax, where A is an arbitrary expanding d×d matrix with integer coefficients. Firstly, through two arbitrarily multiwavelet frames, we give a simple construction of a pair of orthogonal multiwavelet frames. Then, by using the unitary extension principle, we present an algorithm for the construction of arbitrarily many orthogonal multiwavelet tight frames. Finally, we give a general construction algorithm for orthogonal multiwavelet tight frames from a scaling function.

  18. Knowledge sources in L2 learning

    Directory of Open Access Journals (Sweden)

    Diana Ayliff

    2011-08-01

    Full Text Available Should one bother to teach grammar to second language (L2 learners of English? The purpose of this article is to examine the hypothesis that there is an interface between explicit and implicit knowledge sources. Three groups of learners at the Nelson Mandela Metropolitan University were asked to articulate, first without a prompt and then with a prompt, the grammatical rules they were applying to correct common errors.  The test results suggest that there is a high correlation between what they seemingly know implicitly and the hidden, possibly previously explicit knowledge source on which they are drawing.  The article concludes by discussing some of the theoretical implications of the research.

  19. Negative evidence in L2 acquisition

    Directory of Open Access Journals (Sweden)

    Anne Dahl

    2005-02-01

    Full Text Available This article deals with the L2 acquisition of differences between Norwegian and English passives, and presents data to show that the acquisition of these differences by Norwegian L2 acquirers of English cannot be fully explained by positive evidence, cues, conservativism or economy. Rather, it is argued, it is natural to consider whether indirect negative evidence may facilitate acquisition by inferencing. The structures in focus are impersonal passive constructions with postverbal NPs and passive constructions with intransitive verbs. These sentences are ungrammatical in English. Chomsky (1981 proposes that this is a result of passive morphology absorbing objective case in English. There is no such case to be assigned to the postverbal NP in impersonal passives. In passive constructions with intransitive verbs, the verb does not assign objective case, so that there is no case for the passive morphology to absorb. Thus, impersonal passives have to be changed into personal passives, where the NP receives nominative case, and the objective case is free to go to the passive morphology. Intransitive verbs, however, cannot be used in the passive voice at all. Both the structures discussed in this article, i.e. are grammatical in Norwegian. However, the options available in English, viz. personal passives and active sentences, are equally possible. Åfarli (1992 therefore proposes that Norwegian has optional case absorption (passive morphology optionally absorbs case. On the basis on such observations, we may propose a parameter with the settings [+case absorption] for English, and [-case absorption], signifying optional case absorption, for Norwegian. This means that none of the structures that are grammatical in English can function as positive evidence for the [+case absorption] setting, since they are also grammatical in optional case absorption languages. The question is how this parameter is set.

  20. L2 Willingness to Communicate, Openness to Experience, Extraversion, and L2 Unwillingness to Communicate: The Iranian EFL Context

    Science.gov (United States)

    Khany, Reza; Nejad, Ali Mansouri

    2017-01-01

    This study examines the relationship between L2 willingness to communicate (L2WTC), L2 unwillingness to communicate (L2UWTC) and the personality traits of openness to experience and extraversion in an Iranian context. The Pearson correlation and descriptive statistics were used to analyse the results from a study with 217 English major students. A…

  1. Transfer and Semantic Universals in the L2 Acquisition of the English Article System by Child L2 Learners

    Science.gov (United States)

    Morales-Reyes, Alexandra; Soler, Inmaculada Gómez

    2016-01-01

    L2 learners' problems with English articles have been linked to learners' L1 and their access to universal semantic features (e.g., definiteness and specificity). Studies suggest that L2 adults rely on their L1 knowledge, while child L2 learners rely more on their access to semantic universals. The present study investigates whether child L2

  2. Low Parametric Sensitivity Realizations with relaxed L2-dynamic-range-scaling constraints

    OpenAIRE

    Hilaire, Thibault

    2009-01-01

    This paper presents a new dynamic-range scaling for the implementation of filters/controllers in state-space form. Relaxing the classical L2-scaling constraints by specific fixed-point considerations allows for a higher degree of freedom for the optimal L2-parametric sensitivity problem. However, overflows in the implementation are still prevented. The underlying constrained problem is converted into an unconstrained problem for which a solution can be provided. This leads to realizations whi...

  3. Low Parametric Sensitivity Realizations with relaxed L2-dynamic-range-scaling constraints

    OpenAIRE

    Hilaire, Thibault

    2009-01-01

    This paper presents a new dynamic-range scaling for the implementation of filters/controllers in state-space form. Relaxing the classical L2-scaling constraints by specific fixed-point considerations allows for a higher degree of freedom for the optimal L2-parametric sensitivity problem. However, overflows in the implementation are still prevented. The underlying constrained problem is converted into an unconstrained problem for which a solution can be provided. This leads to realizations whi...

  4. The L2 Acquisition of English Passive%The L2Acquisition of English Passive

    Institute of Scientific and Technical Information of China (English)

    张丽

    2015-01-01

    Passive voice is an important grammatical category in language learning while it varies in different languages.In order to diminish the negative impact on L1 transfer and maintain the originality of passive voice in L2 learning,this essay centers on the grammatical differences of passive voice both in English and Chinese and propose practical teaching strategies.

  5. On the Relationship between Iranian L2 Teachers' Pedagogical Beliefs and L2 Learners' Attitudes

    Science.gov (United States)

    Sharajabian, Maryam; Hashemian, Mahmood

    2015-01-01

    The present study employed a descriptive survey design to investigate L2 learners' attitudes towards language learning, and the possible effects of teachers' beliefs on learners' attitudes. Participants were chosen from among 2 groups: Twenty EFL teachers were asked to take part in this study and 80 from a pool of 213 learners at 2 language…

  6. Revisiting Fluctuations in L2 Article Choice in L1-Korean L2-English Learners.

    Science.gov (United States)

    Sarker, Bijon K; Baek, Seunghyun

    2016-06-25

    The current study investigated the distinction of L2 (second language) English article choice sensitivity in fifty-three L1-Korean L2-English learners in semantic contexts. In the context of English as a foreign language, the participants were divided into two groups based on grammatical ability as determined by their performance on a cloze test. In addition, a forced-choice elicitation test and a writing production test were administered to assess, respectively, the participants' receptive and productive article choice abilities. Regardless of grammatical ability, the results disclosed the overuse of the indefinite a in the [[Formula: see text]definite, -specific] context and the definite the in the [-definite, [Formula: see text]specific] context on the forced-choice elicitation test. In the [[Formula: see text]definite, [Formula: see text]specific] and [-definite, -specific] contexts, however, the overuse of either the indefinite a or the definite the, respectively, was less likely. Furthermore, it was revealed on the writing test that the participants more accurately used the definite the than the indefinite a, and they were also found to unreasonably omit more articles than to add or substitute articles on the writing production test. The findings across the two tests indicate that L1-Korean L2-English learners are more likely to have intrinsic difficulties transferring their L1 noun phrase (NP) knowledge to L2 NP knowledge owing to structural discrepancies and complex interfaces between L1 NPs and L2 NPs with respect to syntactic, semantic and pragmatic/discourse language subsystems.

  7. Possible effect of explicit knowledge on L2 learning

    Institute of Scientific and Technical Information of China (English)

    尚冰玉

    2014-01-01

    Ellis (2004) had given a specific working definition of explicit knowledge in the definition and measure-ment of L2 explicit knowledge. He said this kind of knowledge is“the conscious awareness of what a lan-guage or language in general consists of and / or of the roles that it plays in human life.” To be more specific, explicit knowledge is part of declarative memory, and it is stored in the limbic system of the brain. Besides, it is always presented in consciousness and can be verbalized. For example, a L2 learner can point out that in this sentence“The boy plays basketball”.“-S”should be put after the predicate“play”, because the subject of the sentence is the third person singular pronoun. Also, the process of learning explicit knowledge is controlled or monitored. In general, experts test explicit knowledge mainly by grammar. But there are also some other aspects of explicit knowledge that need to be considered, such as the pronunciation, vocabulary, pragmatic features and so on. This essay considers what effect of the as-pects I have mentioned above might have on second language learning.

  8. Acquisition of motion in L2 Estonian

    Directory of Open Access Journals (Sweden)

    Liis Nelis

    2016-05-01

    Full Text Available This study focuses on the acquisition of Motion in Estonian by native English speakers. The aim was to determine how English learners of Estonian are influenced by their first language (L1 when describing Motion events in Estonian as their second language (L2. Prior studies have claimed that people develop certain ways of thinking for speaking when learning their first language which affect the acquisition of other languages (e.g. Slobin 1996, Pool, Pajusalu 2012 i.a.. In order to find out how native English speakers are influenced by their L1 when acquiring Motion in Estonian, an experiment was implemented on 22 participants (11 native English speakers and 11 native Estonian speakers in which they were asked to write a short narrative in Estonian based on a picture book by Mayer (1969. The Motion events found in the narratives were analysed one by one. The findings suggest that L1 thinking patterns influence the intermediate learners more than the advanced or beginner learners, thus partly supporting the findings of Cadierno and Ruiz (2006 who reached a similar conclusion.

  9. Proficiency effect on L2 pragmatic competence

    Directory of Open Access Journals (Sweden)

    Feng Xiao

    2015-12-01

    Full Text Available This paper synthesizes cross-sectional studies of the effect of proficiency on second language (L2 pragmatics to answer the synthesis question: Does proficiency affect adult learners’ pragmatic competence? Findings have revealed an overall positive proficiency effect on pragmatic competence, and in most cases higher proficiency learners have higher pragmatic competence. However, increased proficiency does not guarantee a native-like pragmatic performance because proficiency effect varies depending on the nature of target pragmatic features such as types of speech acts (degrees of directness and conventionality (e.g., Cook & Liddicoat, 2002; Félix-Brasdefer, 2007, modalities of pragmatic performance (comprehension and production (e.g., Bradovi-Harlig, 2008, 2009, social variables involved in task situations, such as social status (e.g., Allami & Naeimi, 2011, social distance (e.g., Maeshiba, Yoshinaga, Kasper, & Ross, 1996, and power relationship (e.g., Al-Gahtani & Roever, 2012. Moreover, proficiency effect is mediated by contextual variables such as length of stay in the target language community (e.g., Shardakova, 2005; Taguchi, 2011, 2013; Xu, Case, & Wang, 2009.

  10. ASC Trilab L2 Codesign Milestone 2015

    Energy Technology Data Exchange (ETDEWEB)

    Trott, Christian Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hammond, Simon David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dinge, Dennis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lin, Paul T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vaughan, Courtenay T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cook, Jeanine [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Edwards, Harold C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rajan, Mahesh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hoekstra, Robert J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    For the FY15 ASC L2 Trilab Codesign milestone Sandia National Laboratories performed two main studies. The first study investigated three topics (performance, cross-platform portability and programmer productivity) when using OpenMP directives and the RAJA and Kokkos programming models available from LLNL and SNL respectively. The focus of this first study was the LULESH mini-application developed and maintained by LLNL. In the coming sections of the report the reader will find performance comparisons (and a demonstration of portability) for a variety of mini-application implementations produced during this study with varying levels of optimization. Of note is that the implementations utilized including optimizations across a number of programming models to help ensure claims that Kokkos can provide native-class application performance are valid. The second study performed during FY15 is a performance assessment of the MiniAero mini-application developed by Sandia. This mini-application was developed by the SIERRA Thermal-Fluid team at Sandia for the purposes of learning the Kokkos programming model and so is available in only a single implementation. For this report we studied its performance and scaling on a number of machines with the intent of providing insight into potential performance issues that may be experienced when similar algorithms are deployed on the forthcoming Trinity ASC ATS platform.

  11. L2, the minor capsid protein of papillomavirus

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Joshua W. [Department of Pathology, The Johns Hopkins University, Baltimore, MD 21287 (United States); Roden, Richard B.S., E-mail: roden@jhmi.edu [Department of Pathology, The Johns Hopkins University, Baltimore, MD 21287 (United States); Department of Oncology, The Johns Hopkins University, Baltimore, MD 21287 (United States); Department of Gynecology and Obstetrics, The Johns Hopkins University, Baltimore, MD 21287 (United States)

    2013-10-15

    The capsid protein L2 plays major roles in both papillomavirus assembly and the infectious process. While L1 forms the majority of the capsid and can self-assemble into empty virus-like particles (VLPs), L2 is a minor capsid component and lacks the capacity to form VLPs. However, L2 co-assembles with L1 into VLPs, enhancing their assembly. L2 also facilitates encapsidation of the ∼8 kbp circular and nucleosome-bound viral genome during assembly of the non-enveloped T=7d virions in the nucleus of terminally differentiated epithelial cells, although, like L1, L2 is not detectably expressed in infected basal cells. With respect to infection, L2 is not required for particles to bind to and enter cells. However L2 must be cleaved by furin for endosome escape. L2 then travels with the viral genome to the nucleus, wherein it accumulates at ND-10 domains. Here, we provide an overview of the biology of L2. - Highlights: • L2 is the minor antigen of the non-enveloped T=7d icosahedral Papillomavirus capsid. • L2 is a nuclear protein that can traffic to ND-10 and facilitate genome encapsidation. • L2 is critical for infection and must be cleaved by furin. • L2 is a broadly protective vaccine antigen recognized by neutralizing antibodies.

  12. Development and implementation of a novel assay for L-2-hydroxyglutarate dehydrogenase (L-2-HGDH) in cell lysates: L-2-HGDH deficiency in 15 patients with L-2-hydroxyglutaric aciduria.

    Science.gov (United States)

    Kranendijk, M; Salomons, G S; Gibson, K M; Aktuglu-Zeybek, C; Bekri, S; Christensen, E; Clarke, J; Hahn, A; Korman, S H; Mejaski-Bosnjak, V; Superti-Furga, A; Vianey-Saban, C; van der Knaap, M S; Jakobs, C; Struys, E A

    2009-12-01

    L-2-hydroxyglutaric aciduria (L-2-HGA) is a rare inherited autosomal recessive neurometabolic disorder caused by mutations in the gene encoding L-2-hydroxyglutarate dehydrogenase. An assay to evaluate L-2-hydroxyglutarate dehydrogenase (L-2-HGDH) activity in fibroblast, lymphoblast and/or lymphocyte lysates has hitherto been unavailable. We developed an L-2-HGDH enzyme assay in cell lysates based on the conversion of stable-isotope-labelled L-2-hydroxyglutarate to 2-ketoglutarate, which is converted into L-glutamate in situ. The formation of stable isotope labelled L-glutamate is therefore a direct measure of L-2-HGDH activity, and this product is detected by liquid chromatography-tandem mass spectrometry. A deficiency of L-2-HGDH activity was detected in cell lysates from 15 out of 15 L-2-HGA patients. Therefore, this specific assay confirmed the diagnosis unambiguously affirming the relationship between molecular and biochemical observations. Residual activity was detected in cells derived from one L-2-HGA patient. The L-2-HGDH assay will be valuable for examining in vitro riboflavin/FAD therapy to rescue L-2-HGDH activity.

  13. Evidence from adult L1 Afrikaans L2 French

    African Journals Online (AJOL)

    (UG) is operative in adult L2 acquisition, have investigated the role that ... ungrammatical in the L2, and consists of explicit teaching and corrective feedback (Schwartz ..... unlike L1 learners, employ their general problem-solving skills (rather.

  14. Gender Bender: Gender Errors in L2 Pronoun Production

    Science.gov (United States)

    Anton-Mendez, Ines

    2010-01-01

    To address questions about information processing at the message level, pronoun errors of second language (L2) speakers of English were studied. Some L2 pronoun errors--"he/she" confusions by Spanish speakers of L2 English--could be due to differences in the informational requirements of the speakers' two languages, providing a window into the…

  15. A Conceptual Review of Age Effect on L2 Acquisition

    Science.gov (United States)

    Sang, Yuan

    2017-01-01

    The importance of age effect on an additional language (L2) acquisition has long been recognized in the field of L2 education. Research was conducted to reveal the influence of age to the rate and ultimate attainment of L2 teaching and learning, yet controversial results were discovered. Consequently, stereotypes and misunderstanding exist among…

  16. Peer Response to L2 Student Writing: Patterns and Expectations

    Science.gov (United States)

    Abdalla Salih, Abdel Rahman

    2013-01-01

    This paper reports the corrective feedback patterns in L2 writing and the student writers' preferences for peer feedback. The study examines the actual focus of peer review and the types of corrective feedback provided in L2 composing process. Sixteen L2 matriculation students at a Malaysian university took part in five peer review sessions,…

  17. Seroepidemiology of Human Papillomavirus 16 (HPV16) L2 and Generation of L2-Specific Human Chimeric Monoclonal Antibodies

    National Research Council Canada - National Science Library

    Wang, Joshua W; Jagu, Subhashini; Wu, Wai-Hong; Viscidi, Raphael P; Macgregor-Das, Anne; Fogel, Jessica M; Kwak, Kihyuck; Daayana, Sai; Kitchener, Henry; Stern, Peter L; Gravitt, Patti E; Trimble, Cornelia L; Roden, Richard B S

    2015-01-01

    Presently, the seroprevalence of human papillomavirus (HPV) minor capsid antigen L2-reactive antibody is not well understood, and no serologic standard exists for L2-specific neutralizing antibodies...

  18. An overview of L-2-hydroxyglutarate dehydrogenase gene (L2HGDH) variants: a genotype-phenotype study

    DEFF Research Database (Denmark)

    Steenweg, Marjan E; Jakobs, Cornelis; Errami, Abdellatif;

    2010-01-01

    L-2-Hydroxyglutaric aciduria (L2HGA) is a rare, neurometabolic disorder with an autosomal recessive mode of inheritance. Affected individuals only have neurological manifestations, including psychomotor retardation, cerebellar ataxia, and more variably macrocephaly, or epilepsy. The diagnosis of ...

  19. An overview of L-2-hydroxyglutarate dehydrogenase gene (L2HGDH) variants: a genotype-phenotype study

    DEFF Research Database (Denmark)

    Steenweg, Marjan E; Jakobs, Cornelis; Errami, Abdellatif;

    2010-01-01

    L-2-Hydroxyglutaric aciduria (L2HGA) is a rare, neurometabolic disorder with an autosomal recessive mode of inheritance. Affected individuals only have neurological manifestations, including psychomotor retardation, cerebellar ataxia, and more variably macrocephaly, or epilepsy. The diagnosis of ...... variants (http://www.LOVD.nl/L2HGDH). Every user can access the database and submit variants/patients. Furthermore, we report on the phenotype, including neurological manifestations and urinary levels of L2HG, and we evaluate the phenotype-genotype relationship....

  20. The Role of L1 and L2 Working Memory in Literal and Inferential Comprehension in L2 Reading

    Science.gov (United States)

    Alptekin, Cem; Ercetin, Gulcan

    2010-01-01

    Reading span as a measure of L1 or L2 working memory capacity is shown to be related to L2 reading comprehension. Albeit limited, there is research on the relationship between both L1 and L2 reading spans and their roles in L2 reading comprehension, yet these studies take reading as a global construct rather than delving into its multi-level…

  1. Analysis list: TCF7L2 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available TCF7L2 Blood,Breast,Digestive tract,Liver,Pancreas,Prostate,Uterus + hg19 http://db...archive.biosciencedbc.jp/kyushu-u/hg19/target/TCF7L2.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/TCF7L2.5.tsv http:...//dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/TCF7L2.10.tsv http://dbarchive.bio...sciencedbc.jp/kyushu-u/hg19/colo/TCF7L2.Blood.tsv,http://dbarchive.biosciencedbc....jp/kyushu-u/hg19/colo/TCF7L2.Breast.tsv,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/TCF7L2.Digestive_tract.tsv,http:

  2. Orbital Maneuvers for Spacecrafts Travelling to/from the Lagrangian Points

    Science.gov (United States)

    Bertachini, A.

    The well-known Lagrangian points that appear in the planar restricted three-body problem (Szebehely, 1967) are very important for astronautical applications. They are five points of equilibrium in the equations of motion, what means that a particle located at one of those points with zero velocity will remain there indefinitely. The collinear points (L1, L2 and L3) are always unstable and the triangular points (L4 and L5) are stable in the present case studied (Sun-Earth system). They are all very good points to locate a space-station, since they require a small amount of V (and fuel), the control to be used for station-keeping. The triangular points are specially good for this purpose, since they are stable equilibrium points. In this paper, the planar restricted three-body problem is regularized (using Lemaître regularization) and combined with numerical integration and gradient methods to solve the two point boundary value problem (the Lambert's three-body problem). This combination is applied to the search of families of transfer orbits between the Lagrangian points and the Earth, in the Sun-Earth system, with the minimum possible cost of the control used. So, the final goal of this paper is to find the magnitude and direction of the two impulses to be applied in the spacecraft to complete the transfer: the first one when leaving/arriving at the Lagrangian point and the second one when arriving/living at the Earth. This paper is a continuation of two previous papers that studied transfers in the Earth-Moon system: Broucke (1979), that studied transfer orbits between the Lagrangian points and the Moon and Prado (1996), that studied transfer orbits between the Lagrangian points and the Earth. So, the equations of motion are: whereis the pseudo-potential given by: To solve the TPBVP in the regularized variables the following steps are used: i) Guess a initial velocity Vi, so together with the initial prescribed position ri the complete initial state is known; ii

  3. Vocabulary Development in Norwegian L1 and L2 Learners in the Kindergarten-School Transition

    Science.gov (United States)

    Karlsen, Jannicke; Lyster, Solveig-Alma Halaas; Lervåg, Arne

    2017-01-01

    This study examined the vocabulary development of Norwegian second language (L2) learners with Urdu/Punjabi as their first language (L1) at two time-points from kindergarten to primary school, and compared it to the vocabulary development of monolingual Norwegian children. Using path models, the associations between number of picture books in the…

  4. Using Learning Strategies:A Review in L2 Listening Research

    Institute of Scientific and Technical Information of China (English)

    田秀峰

    2013-01-01

    This paper briefly reviews some significant learning strategies in L2 listening research. By pointing out both the feasibil⁃ities and difficulties in implementing those strategies in Chinese EFL classrooms, it attempts to raise English language practitio⁃ners’awareness of reforming the listening instruction and of utilizing strategic teaching approaches so as to enhance students’lis⁃tening proficiency.

  5. The Ontological Status of Learner Grammaticality Judgments to UG Approaches to L2 Acquisition.

    Science.gov (United States)

    Christie, Katrien and Lantolf, James P.

    1992-01-01

    Reports on grammaticality judgments by early learners of a second language (Italian). The data, contrary to what might be assumed, point to no relationship between intuition and performance for L2 Learners. Data concerning advanced learners may prove to be more valid. (34 references) (LET)

  6. L2 Learner Age from a Contextualised Perspective

    Science.gov (United States)

    Djigunovic, Jelena Mihaljevic

    2014-01-01

    In this qualitative study the author focuses on age effects on young learners' L2 development by comparing the L2 learning processes of six young learners in an instructed setting: three who had started learning English as L2 at age 6/7 and three who had started at age 9/10. Both earlier and later young beginners were followed for three years…

  7. Working memory and L2 reading: theoretical and methodological issues

    OpenAIRE

    Erçetin, Gülcan

    2015-01-01

    This article reviews research on working memory (WM) and its role in second language (L2) reading. After a brief theoretical account of WM, the article focuses on methods of measuring WM and issues surrounding its measurement. Next, the paper provides a review of studies on the relationship between L1 and L2 WM, their relationships with L2 reading, and the interaction between WM capacity and domain knowledge in terms of their effects on L2 reading comprehension. Conclusions regarding the role...

  8. L2, the minor capsid protein of papillomavirus

    Science.gov (United States)

    Wang, Joshua W.; Roden, Richard B.S.

    2013-01-01

    The capsid protein L2 plays major roles in both papillomavirus assembly and the infectious process. While L1 forms the majority of the capsid and can self-assemble into empty virus-like particles (VLPs), L2 is a minor capsid component and lacks the capacity to form VLPs. However, L2 co-assembles with L1 into VLPs, enhancing their assembly. L2 also facilitates encapsidation of the ~8kbp circular and nucleosome-bound viral genome during assembly of the non-enveloped T=7d virions in the nucleus of terminally differentiated epithelial cells, although, like L1, L2 is not detectably expressed in infected basal cells. With respect to infection, L2 is not required for particles to bind to and enter cells. However L2 must be cleaved by furin for endosome escape. L2 then travels with the viral genome to the nucleus, wherein it accumulates at ND-10 domains. Here, we provide an overview of the biology of L2. PMID:23689062

  9. Motivational dimension of willingness to communicate in L2: The impacts of criterion measure, ideal L2 self, family influence, and attitudes to L2 culture

    Directory of Open Access Journals (Sweden)

    Afsaneh Ghanizadeh

    2016-07-01

    Full Text Available The purpose of the present study is to explore the interrelationship between four components of Dörnyei's Motivational Self-System (criterion measure, ideal L2 self, attitudes to L2 culture and community, and family influence and willingness to communicate in the second language (L2 WTC. Questionnaire data were collected from 160 Iranian EFL learners. Results of multiple regression analysis indicated that four aforementioned motivational factors can account for approximately 10 percent of the variance in WTC among Iranian EFL learners. Furthermore, this study found that WTC correlated significantly and positively with all motivational factors except family influence. Besides, it was found that among the components of WTC, WTC in reading correlated with both criterion measure and ideal L2 self. WTC in writing did not correlate with any of the motivational factors. WTC in listening was associated with criterion measure as well as ideal L2 self, although the magnitude of correlation with ideal L2 self was higher. The discussion and implications of the findings are presented with reference to the earlier findings.

  10. Event-related brain potentials and second language learning: syntactic processing in late L2 learners at different L2 proficiency levels

    NARCIS (Netherlands)

    Hell, J.G. van; Tokowicz, N.

    2010-01-01

    There are several major questions in the literature on late second language (L2) learning and processing. Some of these questions include: Can late L2 learners process an L2 in a native-like way? What is the nature of the differences in L2 processing among L2 learners at different levels of L2 profi

  11. Event-related brain potentials and second language learning: syntactic processing in late L2 learners at different L2 proficiency levels

    NARCIS (Netherlands)

    Hell, J.G. van; Tokowicz, N.

    2010-01-01

    There are several major questions in the literature on late second language (L2) learning and processing. Some of these questions include: Can late L2 learners process an L2 in a native-like way? What is the nature of the differences in L2 processing among L2 learners at different levels of L2

  12. Identification of a new DPY19L2 mutation and a better definition of DPY19L2 deletion breakpoints leading to globozoospermia.

    Science.gov (United States)

    Ghédir, Houda; Ibala-Romdhane, Samira; Okutman, Ozlem; Viot, Géraldine; Saad, Ali; Viville, Stéphane

    2016-01-01

    The purpose of this study was to analyze DPY19L2 sequence variants to investigate the mechanism leading to the entire DPY19L2 deletion in a large cohort of infertile globozoospermic patients. An improved analysis of the DPY19L2 deletion breakpoints (BPs) allowed us to identify two BPs located in a small 1 kb region and to more precisely localize the BPs reported previously. Three genes [spermatogenesis associated 16 (SPATA16), protein interacting with PRKCA (PICK1) and DPY19L2] were previously correlated with globozoospermia, but a homozygous deletion of the entire DPY19L2 was identified as the most frequent alteration causing this phenotype. In addition, several point mutations in this gene were reported. In previous work, we have identified nine BPs for the DPY19L2 deletion clustered in two hotspot regions, while others reported a total of five BPs. We screened for the DPY19L2 deletion and for mutations in the DPY19L2, SPATA16 and PICK1 genes in a cohort of 21 Tunisian globozoospermic patients. In order to characterize the DPY19L2 deletion BPs, we sequenced a 2 kb fragment on low copy repeat (LCR) 1 and LCR2 in Tunisian fertile controls to distinguish between single-nucleotide polymorphisms (SNPs) and LCR-specific markers. Molecular analyses performed on 18 genetically independent individuals showed that 11 (61.1%) were homozygous for the DPY19L2 deletion, 2 (11.1%) were homozygous for the non-synonymous mutation (p.R298C) in exon 8, 1 patient (5.6%) was homozygous for a new splice-site mutation at the junction exon-intron 16 [c.1579_1580+4delAGGTAAinsTCAT] and no DPY19L2, SPATA16 or PICK1 mutations were identified for 4 patients (22.2%). By defining 15 specific LCR markers, we characterized 2 BPs for the DPY19L2 deletion in 11 patients showing the homozygous deletion. Using 20 non-LCR-specific SNPs, we identified 8 distinct haplotypes. A limitation of this study is the small number of patients owing to the rarity of this form of male infertility. Our data showed

  13. Neural changes underlying early stages of L2 vocabulary acquisition.

    Science.gov (United States)

    Pu, He; Holcomb, Phillip J; Midgley, Katherine J

    2016-11-01

    Research has shown neural changes following second language (L2) acquisition after weeks or months of instruction. But are such changes detectable even earlier than previously shown? The present study examines the electrophysiological changes underlying the earliest stages of second language vocabulary acquisition by recording event-related potentials (ERPs) within the first week of learning. Adult native English speakers with no previous Spanish experience completed less than four hours of Spanish vocabulary training, with pre- and post-training ERPs recorded to a backward translation task. Results indicate that beginning L2 learners show rapid neural changes following learning, manifested in changes to the N400 - an ERP component sensitive to lexicosemantic processing and degree of L2 proficiency. Specifically, learners in early stages of L2 acquisition show growth in N400 amplitude to L2 words following learning as well as a backward translation N400 priming effect that was absent pre-training. These results were shown within days of minimal L2 training, suggesting that the neural changes captured during adult second language acquisition are more rapid than previously shown. Such findings are consistent with models of early stages of bilingualism in adult learners of L2 (e.g. Kroll and Stewart's RHM) and reinforce the use of ERP measures to assess L2 learning.

  14. Promoting L2 Vocabulary Learning through Narrow Reading

    Science.gov (United States)

    Kang, Eun Young

    2015-01-01

    Krashen (2004) has advocated that narrow reading, i.e., reading a series of texts addressing one specific topic, is an effective method to grow vocabulary. While narrow reading has been championed to have many advantages for L2 vocabulary learning, there remains a relative dearth of empirical studies that test the impact of narrow reading on L2

  15. L2-Betti numbers of locally compact groups

    DEFF Research Database (Denmark)

    Petersen, Henrik Densing

    We introduce a notion of L2-Betti numbers for locally compact, second countable, unimodular groups. We study the relation to the standard notion of L2-Betti numbers of countable discrete groups for lattices. In this way, several new computations are obtained for countable groups, including lattices...

  16. Prosodic and Lexical Marking of Contrast in L2 Italian

    Science.gov (United States)

    Turco, Giuseppina; Dimroth, Christine; Braun, Bettina

    2015-01-01

    We investigated the second language (L2) acquisition of pragmatic categories that are not as consistently and frequently encoded in the L2 than in the first language (L1). Experiment 1 showed that Italian speakers linguistically highlighted affirmative polarity contrast (e.g. "The child ate the candies" following after "The child…

  17. Proficiency and Sequential Organization of L2 Requests

    Science.gov (United States)

    Al-Gahtani, Saad; Roever, Carsten

    2012-01-01

    L2 requests in developmental pragmatics research are commonly investigated using non-interactive data collection techniques or sidelining the larger discourse sequence in which the request proper is embedded. This study takes a different approach to the study of L2 requests. In a cross-sectional design, we collected role play data from learners at…

  18. Design Issues and Inference in Experimental L2 Research

    Science.gov (United States)

    Hudson, Thom; Llosa, Lorena

    2015-01-01

    Explicit attention to research design issues is essential in experimental second language (L2) research. Too often, however, such careful attention is not paid. This article examines some of the issues surrounding experimental L2 research and its relationships to causal inferences. It discusses the place of research questions and hypotheses,…

  19. Vocabulary Acquisition in L2: Does CALL Really Help?

    Science.gov (United States)

    Averianova, Irina

    2015-01-01

    Language competence in various communicative activities in L2 largely depends on the learners' size of vocabulary. The target vocabulary of adult L2 learners should be between 2,000 high frequency words (a critical threshold) and 10,000 word families (for comprehension of university texts). For a TOEIC test, the threshold is estimated to be…

  20. Lexical Patterns in L2 Textual Gist Identification Assessment

    Science.gov (United States)

    Yamada, Kyoko

    2009-01-01

    Gist identification or coherent situation model construction performance is an important criterion not only in L1 and L2 reading comprehension assessment but also in every aspect of discourse processing. Whereas most previous L2 research has investigated schematic knowledge of readers about relations within a text, more recent studies have used…

  1. L2 learner age from a contextualised perspective

    Directory of Open Access Journals (Sweden)

    Jelena Mihaljeviđ Djigunoviđ

    2014-01-01

    Full Text Available In this qualitative study the author focuses on age effects on young learners’ L2 development by comparing the L2 learning processes of six young learners in an instructed setting: three who had started learning English as L2 at age 6/7 and three who had started at age 9/10. Both earlier and later young beginners were followed for three years (during their second, third and fourth year of learning English. The participants’ L2 development was measured through their oral output elicited by a two-part speaking task administered each year. Results of the analyses are interpreted taking into account each learners’ individual characteristics (learning ability, attitudes and motivation, self-concept and the characteristics of the context in which they were learning their L2 (attitudes of school staff and parents to early L2 learning, home support, in-class and out-of-class exposure to L2, socio-economic status. The findings show that earlier and later young beginners follow different trajectories in their L2 learning, which reflects different interactions which age enters into with the other variables.

  2. Discussion: How different can perspectives on L2 development be?

    NARCIS (Netherlands)

    Hulstijn, J.H.

    2015-01-01

    In this article I discuss the contributions to this special issue of Language Learning on orders and sequences in second language (L2) development. Using a list of questions, I attempt to characterize what I see as the strengths, limitations, and unresolved issues in the approaches to L2 development

  3. Design Issues and Inference in Experimental L2 Research

    Science.gov (United States)

    Hudson, Thom; Llosa, Lorena

    2015-01-01

    Explicit attention to research design issues is essential in experimental second language (L2) research. Too often, however, such careful attention is not paid. This article examines some of the issues surrounding experimental L2 research and its relationships to causal inferences. It discusses the place of research questions and hypotheses,…

  4. The Effects of L2 Experience on L3 Perception

    Science.gov (United States)

    Onishi, Hiromi

    2016-01-01

    This study examines the influence of experience with a second language (L2) on the perception of phonological contrasts in a third language (L3). This study contributes to L3 phonology by examining the influence of L2 phonological perception abilities on the perception of an L3 at the beginner level. Participants were native speakers of Korean…

  5. Learning L2 Rhythm : Does the direction of acquisition matter?

    NARCIS (Netherlands)

    van Maastricht, Lieke; Krahmer, Emiel; Swerts, Marc; Prieto, Pilar

    2016-01-01

    This study investigates the acquisition of second language (L2) rhythm by speakers of Dutch and Spanish, two languages that traditionally are considered to be rhythmically different. Specifically, it investigates whether the direction in which the L2 is learned (from Dutch to Spanish, or vice versa)

  6. Learning L2 Rhythm : does the direction of acquisition matter?

    NARCIS (Netherlands)

    van Maastricht, Lieke; Krahmer, Emiel; Swerts, Marc; Prieto, Pilar

    2016-01-01

    This study investigates the acquisition of second language (L2) rhythm by speakers of Dutch and Spanish, two languages that traditionally are considered to be rhythmically different. Specifically, it investigates whether the direction in which the L2 is learned (from Dutch to Spanish, or vice versa)

  7. L2-Betti numbers of locally compact groups

    DEFF Research Database (Denmark)

    Petersen, Henrik Densing

    We introduce a notion of L2-Betti numbers for locally compact, second countable, unimodular groups. We study the relation to the standard notion of L2-Betti numbers of countable discrete groups for lattices. In this way, several new computations are obtained for countable groups, including lattices...

  8. Towards Effective Instruction on Aspect in L2 Spanish

    Science.gov (United States)

    Gonzalez, Paz

    2008-01-01

    This study investigates whether L2 instruction on the Spanish aspectual system containing a recognition task of the learners' L1 (Dutch) aspectual system helps the learner to understand and interiorise the L2 system. Second year Dutch university students (N = 20) took part in the experiment. In weekly groups of two to four, the students received…

  9. Honest Bayesian confidence sets for the L2-norm

    NARCIS (Netherlands)

    Szabó, B.; van der Vaart, A.; van Zanten, H.

    2015-01-01

    We investigate the problem of constructing Bayesian credible sets that are honest and adaptive for the L2L2-loss over a scale of Sobolev classes with regularity ranging between [D,2D][D,2D], for some given DD in the context of the signal-in-white-noise model. We consider a scale of prior distributio

  10. Global existence for an L^2 critical Nonlinear Dirac equation in one dimension

    CERN Document Server

    Candy, Timothy

    2011-01-01

    We prove global existence from $L^2$ initial data for a nonlinear Dirac equation known as the Thirring model. Local existence in $H^s$ for $s>0$, and global existence for $s>1/2$, has recently been proven by Selberg and Tesfahun by using $X^{s, b}$ spaces together with a type of null form estimate. In contrast, motivated by the recent work of Machihara, Nakanishi, and Tsugawa, we first prove local existence in $L^2$ by using null coordinates, where the time of existence depends on the profile of the initial data. To extend this to a global existence result we need to rule out concentration of $L^2$ norm, or charge, at a point. This is done by decomposing the solution into an approximately linear component and a component with improved integrability. We then prove global existence for all $s>0$.

  11. SIGNIFICANCE OF RHYTHMIC CULTURAL INPUT IN DEALING WITH FOSSILIZATION IN L2/FL TEACHING

    Institute of Scientific and Technical Information of China (English)

    LiYan

    2004-01-01

    Based on research carried out on four pilot classes,this paper makes surveys how intercultural factors can lead to fossilization in second language learning and foreign language (L2/FL) learning process, so as to highlight the magnificent value of deep-structure cultural transfer in L2/FL teaching and learning procedure. Furthermore. the paper goes deeper into the significance of rhythmic and contrastive cultural input in L2/FL class via analysis on results of sampled items. The paper reaches a conclusion that contrastive deep-structure cultural transfer is basically “I+I” approach in cultural instruction in nature, but the point is how it goes is in accordance with human knowledge/skill acquisition principle.

  12. IMPARARE L’ITALIANO L2 CON LE CANZONI. UN CONTRIBUTO DIDATTICO

    Directory of Open Access Journals (Sweden)

    Elisabetta Mauroni

    2011-07-01

    Full Text Available Il presente contributo si inserisce nel filone degli studi che hanno messo in evidenza la potenziale ricchezza della canzone come strumento di facilitazione dell’apprendimento della L2, e come mezzo per l’approccio al testo letterario per studenti di italiano L1, additandone il carattere di attività particolarmente efficace e ‘consonante’ con una prospettiva umanistico-affettiva, comunicativa, nonché socio-costruttivista. In queste pagine sono presentate alcune attività didattiche (pensate ora per gli apprendenti di italiano L2, ora per gli studenti di italiano L1 formulate a partire da alcuni testi del cantautore Claudio Baglioni (Io sono qui, Le vie dei Colori, Bolero, Fammi andar via tratti dall’album Io sono qui, 1995, edizioni CBS. I testi qui didattizzati sono utilizzabili in diverse prospettive: grammaticale, lessicale, retorica, socio-culturale, ecc.; e per diversi livelli di competenza linguistica (L2: A1-C1; L1.     Learning italian l2 through song.  A didactic contribution   This article is part of a series of studies which focus on the potential richness of songs as tools for facilitating L2 learning, as well as being a way to approach literary texts for L1 Italian students, being a particularly effective activity from a humanistic-affective, communicative and socio-constructivist point of view.  A few didactic activities are presented (designed for L2 Italian learners, or for L1 Italian learners based on songs by Claudio Baglioni (Io sono qui, Le vie dei Colori, Bolero, Fammi andar via from the album Io sono qui, 1995, edizioni CBS.  The texts were adapted for diverse didactic uses: grammatical, lexical, rhetorical, socio-cultural, etc and for different levels of linguistic competence (L2: A1-C1, L1

  13. The effect of computer-assisted translation on L2 learners’ mastery of writing

    Directory of Open Access Journals (Sweden)

    Ahmad Ali Kazemzadeh

    2014-07-01

    Full Text Available Computer-Assisted Translation (CAT is an alternative approach to computer translation that integrates human expertise into the automatic translation process. In this realm, the few studies that deal with Computer Assisted Translation (CAT as a language learning tool focus on its use by advanced learners, not by beginners. Yet, freely available CAT engines (i.e. Google Translate position themselves to cater precisely to the needs of learners with a limited command of a second language (L2. Anecdotal classroom evidence points to beginners availing themselves of CAT help, even against the advice of teachers. In order to find out whether CAT could help develop learners’ writing skills in L2, some tests were run asking participants to write directly into L2 in one instance and into L1 in another, while pre-editing the L1 and post-editing the L2 within the CAT’s Translate.google.com interface. The analysis of the output shows that CAT helps beginners to communicate more, particularly when they have a lesser mastery of the language. The less their mastery of the L2, the greater the difference between the number of words composed with the help of CAT and the number of those written directly into L2. It also helps them to communicate better, with blind marking indicating higher quality when writing with CAT mediation. Looking at the screen recordings, on the other hand, we found that writing directly into L2 requires more effort, as measured by number of pauses, and involves more engagement with the task, as measured by the number of editing interventions.

  14. How to Make L2 Easier to Process ?The Role of L2 Proficiency and Semantic Category in Translation Priming

    Institute of Scientific and Technical Information of China (English)

    XIN WANG

    2014-01-01

    The current study reports four masked translation priming experiments and demonstrates that L2 proficiency plays a role in translation priming but it is not the only factor determining translation priming patterns . Instead , language dominance might be more accurate in predicting priming patterns . Given the asymmetrical representations of L 1 and L2 as described by most bilingual models , the conditions to produce L2‐L1 priming not only depends on the task , but also the category size in semantic categorization . Relevant results will be discussed in relation to bilingual models . One implication of the current results is that processing L2 in a specific semantic context can be optimal to L2 lexical access .

  15. Studies on L2 Learning Motivation of Primary and Middle School Stu-dents from the Perspective of L2 Motivational Self System

    Institute of Scientific and Technical Information of China (English)

    刘凤阁

    2013-01-01

    An empirical survey among 219 school students in the framework of L2 Motivational Self System found that Ideal L2 Self, Ought-to L2 Self and L2 Learning Experience in the System make different contributions to L2 motivation respectively and L2 Learning Experience is the largest contributor to L2 motivation for primary and middle school students. The pedagogical im⁃plications are also suggested.

  16. Integrating Portfolios into the L2 Arabic Classroom

    OpenAIRE

    Husseinali, Ghassan

    2012-01-01

    This is an action research study that reports on using student portfolios in a second language (L2) Arabic class. The goal of this study was to examine the validity of using portfolios as an L2assessment procedure and to ascertain the effectiveness of portfolios as an L2 learning tool. In this class, portfolios replaced weekly quizzes, which counted for 30% of the final grade. Portfolios were also used to supplement the course textbook, namely Al-Kitaab (Brustad, Al-Batal, & Al-Tonsi, 1995).D...

  17. Calibration of comprehension and performance in L2 reading

    Directory of Open Access Journals (Sweden)

    Seda SARAC

    2009-10-01

    Full Text Available Comprehension monitoring is crucial for successful reading. Although the researchers appreciate the importance of comprehension monitoring in L2 reading, there are only a few studies done on the comprehension monitoring ability of L2 readers. The main aim of this study was to investigate the comprehension monitoring abilities of university students while reading expository texts in L2. The results showed that the students’ were not able to calibrate their comprehension at above chance level whereas they were able to calibrate their performance. The results were discussed comparative to findings from earlier research in L1 reading.

  18. Child L2 learning of English in a bilingual setting

    OpenAIRE

    Fleta Guillén, María Teresa

    2004-01-01

    Learning a second language (L2) in a bilingual school can be compared to first language acquisition (L1) in that both processes develop in a natural and unconscious manner. In this paper I investigate the nature of early grammars in second language acquisition. One of the main concerns is whether child learners show a developmental process in L2 acquisition and, if they do, whether there is transference from the children’s L1, and whether the L2 acquisition process resembles the L1 acquisitio...

  19. Integrating Portfolios into the L2 Arabic Classroom

    OpenAIRE

    Husseinali, Ghassan

    2012-01-01

    This is an action research study that reports on using student portfolios in a second language (L2) Arabic class. The goal of this study was to examine the validity of using portfolios as an L2assessment procedure and to ascertain the effectiveness of portfolios as an L2 learning tool. In this class, portfolios replaced weekly quizzes, which counted for 30% of the final grade. Portfolios were also used to supplement the course textbook, namely Al-Kitaab (Brustad, Al-Batal, & Al-Tonsi, 1995).D...

  20. Assimilation of L2 vowels to L1 phonemes governs L2 learning in adulthood: a behavioral and ERP study

    Science.gov (United States)

    Grimaldi, Mirko; Sisinni, Bianca; Gili Fivela, Barbara; Invitto, Sara; Resta, Donatella; Alku, Paavo; Brattico, Elvira

    2014-01-01

    According to the Perceptual Assimilation Model (PAM), articulatory similarity/dissimilarity between sounds of the second language (L2) and the native language (L1) governs L2 learnability in adulthood and predicts L2 sound perception by naïve listeners. We performed behavioral and neurophysiological experiments on two groups of university students at the first and fifth years of the English language curriculum and on a group of naïve listeners. Categorization and discrimination tests, as well as the mismatch negativity (MMN) brain response to L2 sound changes, showed that the discriminatory capabilities of the students did not significantly differ from those of the naïve subjects. In line with the PAM model, we extend the findings of previous behavioral studies showing that, at the neural level, classroom instruction in adulthood relies on assimilation of L2 vowels to L1 phoneme categories and does not trigger improvement in L2 phonetic discrimination. Implications for L2 classroom teaching practices are discussed. PMID:24860470

  1. Assimilation of L2 vowels to L1 phonemes governs L2 learning in adulthood: a behavioral and ERP study.

    Science.gov (United States)

    Grimaldi, Mirko; Sisinni, Bianca; Gili Fivela, Barbara; Invitto, Sara; Resta, Donatella; Alku, Paavo; Brattico, Elvira

    2014-01-01

    According to the Perceptual Assimilation Model (PAM), articulatory similarity/dissimilarity between sounds of the second language (L2) and the native language (L1) governs L2 learnability in adulthood and predicts L2 sound perception by naïve listeners. We performed behavioral and neurophysiological experiments on two groups of university students at the first and fifth years of the English language curriculum and on a group of naïve listeners. Categorization and discrimination tests, as well as the mismatch negativity (MMN) brain response to L2 sound changes, showed that the discriminatory capabilities of the students did not significantly differ from those of the naïve subjects. In line with the PAM model, we extend the findings of previous behavioral studies showing that, at the neural level, classroom instruction in adulthood relies on assimilation of L2 vowels to L1 phoneme categories and does not trigger improvement in L2 phonetic discrimination. Implications for L2 classroom teaching practices are discussed.

  2. A direct comparison between two independently calibrated time transfer techniques: T2L2 and GPS Common-Views

    Science.gov (United States)

    Rovera, G. D.; Abgrall, M.; Courde, C.; Exertier, P.; Fridelance, P.; Guillemot, Ph; Laas-Bourez, M.; Martin, N.; Samain, E.; Sherwood, R.; Torre, J.-M.; Uhrich, P.

    2016-06-01

    We present a direct comparison between two satellite time transfer techniques on independently calibrated links: Time Transfer by Laser Link (T2L2) and Common-Views (CV) of satellites from the Global Positioning System (GPS) constellation. The GPS CV and T2L2 links between three European laboratories where independently calibrated against the same reference point of the local timescales. For all the links the mean values of the differences between GPS CV and T2L2 are equal or below 240 ps, with standard deviations below 500 ps, mostly due to GPS CV. Almost all deviations from 0 ns are within the combined uncertainty estimates. Despite the weak number of common points obtained, due to the fact that T2L2 is weather dependent, these results are providing an unprecedented sub-ns consistency between two independently calibrated microwave and optical satellite time transfer techniques.

  3. The development of conjunction use in advanced L2 speech

    Directory of Open Access Journals (Sweden)

    Marcin Jaroszek

    2011-12-01

    Full Text Available The article discusses the results of a longitudinal study of how the use of conjunctions, as an aspect of spoken discourse competence of 13 selected advanced students of English, developed throughout their 3-year English as a foreign language (EFL tertiary education. The analysis was carried out in relation to a number of variables, including 2 reference levels, one representing English native discourse and the other observed in teacher talk in actual EFL classes, language type exposure, as registered by the participants of the study on a weekly basis, and teaching procedures. The study investigated possible factors determining the development of 3 aspects of conjunction use: (a formal conjunctions, (b specific conjunctions, that is, those conjunctions that are both characteristic of natural English discourse and are underrepresented in L2 discourse, and (c conjunction diversity. The results point to a restricting effect of teacher talk on the development of specific conjunction use and conjunction diversity. These 2 aspects of conjunction use enjoyed only a slight rise, approaching the teacher reference level. On the other hand, formal conjunctions use did increase radically throughout the study, exceeding the native reference level. In this case teacher talk played a reinforcing role at most. As indicated in a correlational analysis, although there was a clear tendency of the participants’ development of conjunction use towards the native reference level, exposure to authentic English may not have been facilitative of the development of this discourse aspect. An interesting observation was made with reference to the effect of formal instruction on the development of conjunction use: Although the subjects did receive intensive training in conjunction use in the 1st semester of their EFL course, it was not until the 2nd year that their levels of formal conjunction use in spoken output increased. This suggests that formal instruction may have

  4. L2-gain and passivity techniques in nonlinear control

    CERN Document Server

    van der Schaft, Arjan

    2017-01-01

    This standard text gives a unified treatment of passivity and L2-gain theory for nonlinear state space systems, preceded by a compact treatment of classical passivity and small-gain theorems for nonlinear input-output maps. The synthesis between passivity and L2-gain theory is provided by the theory of dissipative systems. Specifically, the small-gain and passivity theorems and their implications for nonlinear stability and stabilization are discussed from this standpoint. The connection between L2-gain and passivity via scattering is detailed. Feedback equivalence to a passive system and resulting stabilization strategies are discussed. The passivity concepts are enriched by a generalised Hamiltonian formalism, emphasising the close relations with physical modeling and control by interconnection, and leading to novel control methodologies going beyond passivity. The potential of L2-gain techniques in nonlinear control, including a theory of all-pass factorizations of nonlinear systems, and of parametrization...

  5. Okeanos Explorer (EX1503L2): Tropical Exploration (Mapping II)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During EX-15-03L2, multibeam data will be collected 24 hours a day and XBT casts will be conducted at an interval defined by prevailing oceanographic conditions, but...

  6. Recombinant expression and purification of L2 domain of human ...

    African Journals Online (AJOL)

    USER

    2010-08-16

    Aug 16, 2010 ... and plays an important role in some malignant processes. L2 domain of ..... production of monoclonal antibodies, screening for specific ligands and studies on ... Isolation and characterization of. A-431 cells that retain high ...

  7. Effects of task repetition on L2 oral performance

    OpenAIRE

    Finardi, Kyria Rebeca

    2008-01-01

    This study departs from the assumption that speaking an L2 is a complex cognitive ability (FORTKAMP, 2000) whose execution seems to involve tradeoff effects among the different goals of speech production, mainly among fluency, accuracy and complexity (BYGATE, 1998, 1999, 2001b; FOSTER e SKEHAN, 1996; SKEHAN e FOSTER, 1995, 2001; SKEHAN, 1998). Bygate (2001b) studied the effects of task familiarity on L2 speech performance. He found that in repeating a narrative task there were gains in terms ...

  8. SINGULAR INTEGRAL OPERATORS IN L2 SPACE WITH CHEBYSHEV WEIGHTS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper defines a class of singular integral operators Iwj on L2wj space,where wights wj(j=1-4) are four kinds of Chebyshev weights.The authors prove that Iwj is an unique linear extension of classic singular integral operator Iwj on Holder space,some important properties of Iwj and some results of singular integral equation in L2wj space.

  9. ERP correlates of intramodal and crossmodal L2 acquisition

    Directory of Open Access Journals (Sweden)

    Salden Uta

    2011-05-01

    Full Text Available Abstract Background The present study compared the neural correlates of an intramodally and a crossmodally acquired second language (L2. Deaf people who had learned their L1, German Sign Language (DGS, and their L2, German, through the visual modality were compared with hearing L2 learners of German and German native speakers. Correct and incorrect German sentences were presented word by word on a computer screen while the electroencephalogram was recorded. At the end of each sentence, the participants judged whether or not the sentence was correct. Two types of violations were realized: Either a semantically implausible noun or a violation of subject-verb number agreement was embedded at a sentence medial position. Results Semantic errors elicited an N400, followed by a late positivity in all groups. In native speakers of German, verb-agreement violations were followed by a left lateralized negativity, which has been associated with an automatic parsing process. We observed a syntax related negativity in both high performing hearing and deaf L2 learners as well. Finally, this negativity was followed by a posteriorly distributed positivity in all three groups. Conclusions Although deaf learners have learned German as an L2 mainly via the visual modality they seem to engage comparable processing mechanisms as hearing L2 learners. Thus, the data underscore the modality transcendence of language.

  10. The multipath and SNR Quality in civil code L2

    Science.gov (United States)

    Polezel, W. G.; Souza, E. M.; Monico, J. F.

    2007-12-01

    The new generation of GPS satellites, with the addition of the new L2C civil code, may provide to the users better positioning capabilities. The new code in the L2 may increase the signal robustness, improve resistance to interference, reduce tracking noise and consequently, improve accuracy and provide better positioning inside buildings and in wooded areas. The second civil frequency code will eliminate the need of using fragile semi- codeless tracking techniques currently used in connection with L2. The L2C has a different structure that allows civil and military share the same code. L2C owns two codes of different length: moderate code (CM) and long code (CL). The CM was chosen to have 10.230 chips repeated to every 20 millisecond. The CL was chosen to have 767250 chips with period of 1.5 second. The main reasons for these choices were due to excellent correlation properties. Furthermore, L2C enhances performance by having no data modulation on CL code, which improves, among others, the threshold tracking performance. Comparing the L2C acquisition with the C/A, the CM code is ten times longer than the C/A and the two components have half the total power. This is an important feature for many low-power applications. Although this signal has several advantages, some investigations about its performance are necessary, mainly about the provided accuracy under some effects, for example, multipath. Thus, this paper aims to analyze the L2C signal, as well as its quality using some parameters, such as Signal to Noise Ratio (SNR) and multipath level (MP). The experiment was realized at Sao Paulo State University UNESP in Presidente Prudente, Brazil. The data were collected by two receivers of different brands, both able to collect the L2C signal, and connected to the same antenna, thought the use of a splitter. The results showed that the MP and SNR values were better for the modernized satellites. Furthermore, the SNR values of the two receivers were similar while the

  11. A model of the effect of uncertainty on the C elegans L2/L2d decision.

    Directory of Open Access Journals (Sweden)

    Leon Avery

    Full Text Available At the end of the first larval stage, the C elegans larva chooses between two developmental pathways, an L2 committed to reproductive development and an L2d, which has the option of undergoing reproductive development or entering the dauer diapause. I develop a quantitative model of this choice using mathematical tools developed for pricing financial options. The model predicts that the optimal decision must take into account not only the expected potential for reproductive growth, but also the uncertainty in that expected potential. Because the L2d has more flexibility than the L2, it is favored in unpredictable environments. I estimate that the ability to take uncertainty into account may increase reproductive value by as much as 5%, and discuss possible experimental tests for this ability.

  12. Status of the T2L2/Jason2 Experiment

    Science.gov (United States)

    Exertier, Pierre; Samain, Etienne; Bonnefond, Pascal; Guillemot, Philippe

    2010-12-01

    The T2L2 (Time Transfer by Laser Link) project, developed by CNES and OCA will permit the synchronization of remote ultra stable clocks and the determination of their performances over intercontinental distances. The principle of the experiment derives from Satellite Laser Ranging (SLR) technology with dedicated space equipment. T2L2 was accepted in 2005 to be on board the Jason2 altimetry satellite. The payload consists of both event timer and photo detection modules. The system uses the ultra-stable quartz oscillator of DORIS as on-board reference clock on one hand, and the Laser Reflector Array, making T2L2 a real two-way time transfer system on the other hand. The expected time stability of the T2L2 instrument (detection and timing), referenced by the DORIS oscillator and including all internal error sources should be at the level of 10-12 ps at 1 s and T2L2 should permit to maintain a precision of 1 to a few ps when measuring the phase of a clock during around 1000 seconds. First analysis of T2L2 data permitted to validate some important characteristics of the experiment such as the sensitivity of the instrument to laser pulse amplitude (from single to multi-photon detection mode), data noises (of different sources, SLR and T2L2), and first error budget and time stability of ground to space time transfers. The paper describes the space experiment and highlights the different steps of the data processing after a first year of operations (between July 2008 and June 2009). We show the time stability which can be reached when a laser station is equipped with an Hydrogen Maser or a Cesium clock as a time reference; thus, the first estimations give 7 ps over 30 s. We conclude by presenting the campaigns of ground to ground time transfers already planned between the Paris Observatory and different places in Europe.

  13. Event-Related Brain Potentials and Second Language Learning: Syntactic Processing in Late L2 Learners at Different L2 Proficiency Levels

    Science.gov (United States)

    van Hell, Janet G.; Tokowicz, Natasha

    2010-01-01

    There are several major questions in the literature on late second language (L2) learning and processing. Some of these questions include: Can late L2 learners process an L2 in a native-like way? What is the nature of the differences in L2 processing among L2 learners at different levels of L2 proficiency? In this article, we review studies that…

  14. Sun-earth environment study to understand earthquake prediction

    Science.gov (United States)

    Mukherjee, S.

    2007-05-01

    Earthquake prediction is possible by looking into the location of active sunspots before it harbours energy towards earth. Earth is a restless planet the restlessness turns deadly occasionally. Of all natural hazards, earthquakes are the most feared. For centuries scientists working in seismically active regions have noted premonitory signals. Changes in thermosphere, Ionosphere, atmosphere and hydrosphere are noted before the changes in geosphere. The historical records talk of changes of the water level in wells, of strange weather, of ground-hugging fog, of unusual behaviour of animals (due to change in magnetic field of the earth) that seem to feel the approach of a major earthquake. With the advent of modern science and technology the understanding of these pre-earthquake signals has become stronger enough to develop a methodology of earthquake prediction. A correlation of earth directed coronal mass ejection (CME) from the active sunspots has been possible to develop as a precursor of the earthquake. Occasional local magnetic field and planetary indices (Kp values) changes in the lower atmosphere that is accompanied by the formation of haze and a reduction of moisture in the air. Large patches, often tens to hundreds of thousands of square kilometres in size, seen in night-time infrared satellite images where the land surface temperature seems to fluctuate rapidly. Perturbations in the ionosphere at 90 - 120 km altitude have been observed before the occurrence of earthquakes. These changes affect the transmission of radio waves and a radio black out has been observed due to CME. Another heliophysical parameter Electron flux (Eflux) has been monitored before the occurrence of the earthquakes. More than hundreds of case studies show that before the occurrence of the earthquakes the atmospheric temperature increases and suddenly drops before the occurrence of the earthquakes. These changes are being monitored by using Sun Observatory Heliospheric observatory (SOHO) satellite data. Whatever the manifestations in the environment of the atmosphere or geosphere may be, there is a positive correlation of CMEs with change in magnetic field followed by aurora borealis or sudden spark of light from the sky before an earthquake. Any change in geomorphology in the pixel level, changes in groundwater level, geochemical anomalies of soils surrounding active faults and vegetation anomalies should be monitored in the mirror image position of sunspots on the earth facing side in reference to CME from the sun.

  15. The Maunder minimum and the variable sun-earth connection

    CERN Document Server

    Wei Hock Soon, Willie

    2003-01-01

    This book takes an excursion through solar science, science history, and geoclimate with a husband and wife team who revealed some of our sun's most stubborn secrets. E Walter and Annie S D Maunder's work helped in understanding our sun's chemical, electromagnetic and plasma properties. They knew the sun's sunspot migration patterns and its variable, climate-affecting, inactive and active states in short and long time frames. An inactive solar period starting in the mid-seventeenth century lasted approximately seventy years, one that E Walter Maunder worked hard to make us understand: the Maun

  16. Development of Relative Clause Constructions in English L2

    Directory of Open Access Journals (Sweden)

    Yumiko Yamaguchi

    2016-01-01

    Full Text Available This study explores how relative clause (RC constructions develop in the acquisition of English as a second language (L2. The acquisition of RC constructions has been the focus of much research in the field of language acquisition, but a majority of L2 studies in this area is experimental based on the Noun Phrase Accessibility Hierarchy (NPAH (Keenan & Comrie, 1977. In this study, the spontaneous speech production by a Japanese primary school child, learning English in a naturalistic environment, was audio-recorded regularly over two years, and the development of RC constructions was compared with the acquisition of other English morphological and syntactic structures as represented within Processability Theory (PT (Pienemann, 1998; Pienemann, Di Biase, & Kawaguchi, 2005; Pienemann & Keßler, 2011. Although PT predicts that subordinate clauses are acquired at the highest stage in processability hierarchy, the results in this longitudinal study show that some types of RC constructions emerge at earlier stages in L2 English acquisition. The results also show that RC constructions in the Japanese child’s English L2 develop in the similar way to those reported in L1 studies (e.g., Diessel, 2004.Keywords: relative clause constructions, English L2, Processability Theory, the Noun Phrase Accessibility Hierarchy, Japanese child

  17. Positive aspects of interlinguistic influences in the process of L2 acquisition

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    Sylwia Mikołajczak

    2014-01-01

    Full Text Available The processes that take place in the mind of a multilingual person during the second language acquisition are mostly shrouded in mystery. We can only observe traces of these processes manifesting themselves in the interpenetration of two or more linguistic systems. The current study aims to recognize how the knowledge of L1, in this case Spanish, influences on the acquisition and usage of the target language – Portuguese (L2, and how to take advantage of the interferences to make the L2 learners succeed. The possibility of linguistic influences grows with each acquired language. There are also important contributing factors such as a degree of similarity between the languages, a level of proficiency in each of them, and the manner and time of a language acquisition. During the Portuguese course at the Spanish Philology, we can observe such phenomena as: code switching or total displacement, hybrids, false friends, multi-word units calquing, and morphogrammatical transfer. Although one of the factors that affects the L2 acquisition is the level of proficiency, the students hardly take advantage of their mother tongue, selecting the language typologically closer to Portuguese, Spanish. The students use the previously acquired knowledge to create analogies that should be considered as an intermediate step in the acquisition of L2, not as something negative, but rather a means for providing a starting point for the analysis of error which, consequently, leads to improvement.

  18. Merits and Demerits of CMC in L2 Language Learning

    Institute of Scientific and Technical Information of China (English)

    郭熠

    2015-01-01

    In the digital era,with the rapid development of the computer technology,the possibility and interest of utilizing Internet in L2 language classrooms has gradually increased.In particular,as a useful tool for enhancing language learning and teaching the computer-mediated communication(CMC)through the Internet has become extremely popular over the last five years.Based on the previous literatures,this essay aims not only to discuss a string of actual merits of CMC in terms of L2 teaching and learning but also some demerits belong to it.Furthermore,in order to achieve the most appropriate way to implement CMC into the L2 classroom,some possible solutions for dealing with those disadvantages will also be suggested.

  19. L2TP VPN分析及配置

    Institute of Scientific and Technical Information of China (English)

    陈金莲

    2012-01-01

    在微软的Windows Server 2005中,集成了VPN技术,可以实现Site to Site VPN和L2TPVPN、PPTPVPN两种形式的Eemote Access VPN,其中L2TPVPN、PPTPVPN比较常用。虽然对于大型企业而言,用Windows Server 2003做VPN的可能性不大,但对于小型企业或个人用户来说,用这种VPN实现远程接入不失为一个较好的解决方案。下面,笔者就个人配置经历来详细解析一下L2TP VPN及配置要点。

  20. The TCF7L2 locus and type 1 diabetes

    Directory of Open Access Journals (Sweden)

    Polychronakos Constantin

    2007-08-01

    Full Text Available Abstract Background TCF7L2 belongs to a subfamily of TCF7-like HMG box-containing transcription factors, and maps to human chromosome 10q25.3. A recent study identified genetic association of type 2 diabetes (T2D with this gene, correlated with diminished insulin secretion. This study aimed to investigate the possibility of genetic association between TCF7L2 and type 1 diabetes (T1D. Methods The SNP most significantly associated with T2D, rs7903146, was genotyped in 886 T1D nuclear family trios with ethnic backgrounds of mixed European descent. Results This study found no T1D association with, and no age-of-onset effect from rs7903146. Conclusion This study suggests that a T2D mechanism mediated by TCF7L2 does not participate in the etiology of T1D.

  1. Relative Importance of Learning Variables on L2 Performance

    Directory of Open Access Journals (Sweden)

    Olivares-Cuhat, Gabriela

    2010-01-01

    Full Text Available In this article, the results of a pilot study investigating the relative importance of various learner variables on L2 performance are presented. The study was conducted with the participation of forty students enrolled in a beginning Spanish class at a large midwestern university. The CANAL‑S test, FLCAS and SILL surveys were administered to evaluate language learning aptitude, anxiety and learning strategy use. Demographic data and exam grades were also recorded. The data was first analyzed within the framework of a causal model with correlational and multiple regression analyses. A second step involved the evaluation of the relative importance of the learner variables. Third, the validity of the causality postulated between foreign language anxiety and L2 performance was examined. Overall, this paper confirmed the prevailing role played by language learning aptitude and anxiety, and demonstrated the applicability of a multivariate model to analyze the impact of individual differences on L2 performance.

  2. Controllability of Second-Order Equations in L2

    Directory of Open Access Journals (Sweden)

    Hugo Leiva

    2010-01-01

    Full Text Available We present a simple proof of the interior approximate controllability for the following broad class of second-order equations in the Hilbert space L2(Ω: ÿ+Ay=1ωu(t, t∈(0,τ], y(0=y0, ẏ(0=y1, where Ω is a domain in RN(N≥1, y0,y1∈L2(Ω, ω is an open nonempty subset of Ω, 1ω denotes the characteristic function of the set ω, the distributed control u belongs to L2(0,τ;L2(Ω, and A:D(A⊂L2(Ω→L2(Ω is an unbounded linear operator with the following spectral decomposition: Az=∑j=1∞λj∑k=1γj〈z,ϕj,k〉ϕj,k, with the eigenvalues λj given by the following formula: λj=j2mπ2m, j=1,2,3,… and m≥1 is a fixed integer number, multiplicity γj is equal to the dimension of the corresponding eigenspace, and {ϕj,k} is a complete orthonormal set of eigenvectors (eigenfunctions of A. Specifically, we prove the following statement: if for an open nonempty set ω⊂Ω the restrictions ϕj,kω=ϕj,k|ω of ϕj,k to ω are linearly independent functions on ω, then for all τ≥2/πm-1 the system is approximately controllable on [0,τ]. As an application, we prove the controllability of the 1D wave equation.

  3. Non-optionality at Zulu L2 first syntax

    Directory of Open Access Journals (Sweden)

    Sibusisiwe Dube

    2008-08-01

    Full Text Available The Valueless Features Hypothesis of Eubank (1993/94; 1994; 1996 proposes that certain types of apparently optional syntactic processes that appear in initial and not in mature state grammars are due to a lack of specification of inflectional feature values at the initial state of grammatical knowledge. Thus the apparent optionality in the placement of medial adverbs vis-a-vis thematic or finite main verbs evident in the early stages of second language (L2 acquisition is attributed to non-transfer of the strength values of morphological features instantiated in the learners' first language (LJ. This paper provides experimental evidence from Zulu L2 acquisition of verb raising by English native speakers, which suggests non-optionality in the early developmental stages of L2 syntax. The paper suggests that the initial obligaloriness of a non-verb raising syntactic analysis evident in the early stages of Zulu L2 acquisition is LJ -based; indicating transfer of [- strong] Vfeatures in T instantiated in English. Die 'Valueless Features Hypothesis' van Eubank' (1993/94; 1994; 1996 stel voor dat sekere tipes skynbare opsionele sintaktiese prosesse wat by aanvanklike grammatikas voorkom, maar nie by grammatikas in 'n gevorderde stadium nie, die gevolg is van 'n gebrek aan spesifikasie van infleksionele kenmerkwaardes tydens die aanvanklike stadium van grammatikale kennis. Derhalwe word die skynbare opsionaliteit in die plasing van tussenbywoorde teenoor tematiese of hoofwerkwoorde in 'npersoonsvorm wat by die vroee stadiums van die aankweek van 'n tweede taal (L2 duidelik blyk, toegeskryf aan die nie-oordrag van die kragwaardes van morfologiese kenmerke wat in die leerder se eerste taal (LJ geinstansieer is. Hierdie skripsie lewer eksperimentele bewyse van werkwoordverheffing by die aanleer van Zulu (L2 deur aangebore Engelssprekendes, wat nie-opsionaliteit in die vroee ontwikkelingstadia van L2- sinsleer suggereer. Die skripsie stel voor dat die

  4. A L2HGDH initiator methionine codon mutation in a Yorkshire terrier with L-2-hydroxyglutaric aciduria

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    Farias Fabiana HG

    2012-07-01

    Full Text Available Abstract Background L-2-hydroxyglutaric aciduria is a metabolic repair deficiency characterized by elevated levels of L-2-hydroxyglutaric acid in urine, blood and cerebrospinal fluid. Neurological signs associated with the disease in humans and dogs include seizures, ataxia and dementia. Case presentation Here we describe an 8 month old Yorkshire terrier that presented with episodes of hyperactivity and aggressive behavior. Between episodes, the dog’s behavior and neurologic examinations were normal. A T2 weighted MRI of the brain showed diffuse grey matter hyperintensity and a urine metabolite screen showed elevated 2-hydroxyglutaric acid. We sequenced all 10 exons and intron-exon borders of L2HGDH from the affected dog and identified a homozygous A to G transition in the initiator methionine codon. The first inframe methionine is at p.M183 which is past the mitochondrial targeting domain of the protein. Initiation of translation at p.M183 would encode an N-terminal truncated protein unlikely to be functional. Conclusions We have identified a mutation in the initiation codon of L2HGDH that is likely to result in a non-functional gene. The Yorkshire terrier could serve as an animal model to understand the pathogenesis of L-2-hydroxyglutaric aciduria and to evaluate potential therapies.

  5. A Stable Control of a Cstr with Input Multiplicities Using Artificial Neural Network Based Narma-l2

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    Prabhaker Reddy Ginuga

    2014-01-01

    Full Text Available In this paper, the Neural network based NARMA-L2 controller is analyzed to an isothermal continuous stirred tank reactor (CSTR which exhibits input multiplicities in space velocity on product of B. i.e., two values of space velocity will give the same value of product B. The Performance of Neural network based NARMA-L2 controller and conventional PI controller have been evaluated through simulation studies. As the NARMA-L2 controller provides always the two values of space velocity for control action and by selecting the value nearer to the operating point, it is found to give stable and better responses than conventional PI controller. The PI controller results in unstable condition or switch over from initial lower input space velocity to higher input space velocity vice versa. Thus, NARMA-L2 controller is found to overcome the control problems of PI controller due to the input multiplicities.

  6. Influence of Syllable Structure on L2 Auditory Word Learning

    Science.gov (United States)

    Hamada, Megumi; Goya, Hideki

    2015-01-01

    This study investigated the role of syllable structure in L2 auditory word learning. Based on research on cross-linguistic variation of speech perception and lexical memory, it was hypothesized that Japanese L1 learners of English would learn English words with an open-syllable structure without consonant clusters better than words with a…

  7. Deconstructing Gender Stereotyping through Literature in L2

    Science.gov (United States)

    Yulita, Leticia

    2010-01-01

    While it is generally accepted that literature fosters (inter)cultural learning, few qualitative studies have sought to understand in what ways interculturality is developed. This article investigates the development of Spanish L2 students' intercultural awareness through the reading of a short story entitled "Norma y Ester" by Argentine writer,…

  8. A dynamic usage based perspective on L2 writing

    NARCIS (Netherlands)

    Verspoor, M.H.; Schmid, M.S.; Xu, X.

    2012-01-01

    The goal of this study was to explore the contribution that a dynamic usage based (DUB) perspective can bring to the establishment of objective measures to assess L2 learners' written texts and at the same time to gain insight into the dynamic process of language development. Four hundred and thirty

  9. Can Production Precede Comprehension in L2 Acquisition?

    Science.gov (United States)

    Tasseva-Kurktchieva, Mila

    2015-01-01

    So far, the comprehension and production language modes have typically been studied separately in generative second language acquisition research, with the focus shifting from one to the other. This article revisits the asymmetric relationship between comprehension and production by examining the second language (L2) acquisition of the noun phrase…

  10. SemEval 2014 Task 5 - L2 Writing Assistant

    NARCIS (Netherlands)

    Gompel, M. van; Hendrickx, I.H.E.; Bosch, A.P.J. van den; Lefever, E.; Hoste, V.

    2014-01-01

    We present a new cross-lingual task for SemEval concerning the translation of L1 fragments in an L2 context. The task is at the boundary of Cross-Lingual Word Sense Disambiguation and Machine Translation. It finds its application in the field of computer-assisted translation, particularly in the con

  11. Generators with interior degeneracy on spaces of L^2 type

    Directory of Open Access Journals (Sweden)

    Genni Fragnelli

    2012-10-01

    Full Text Available We consider operators in divergence and in nondivergence form with degeneracy at the interior of the space domain. Characterizing the domain of the operators, we prove that they generate positive analytic semigroups on spaces of L^2 type. Finally, some applications to linear and semilinear parabolic evolution problems and to linear hyperbolic ones are presented.

  12. L2 Processing of Plural Inflection in English

    Science.gov (United States)

    Song, Yoonsang

    2015-01-01

    This study investigates (1) whether late second language (L2) learners can attain native-like knowledge of English plural inflection even when their first language (L1) lacks an equivalent and (2) whether they construct hierarchically structured representations during online sentence processing like native speakers. In a self-paced reading task,…

  13. Learner Negotiation of L2 Form in Transcription Exercises

    Science.gov (United States)

    Mennim, Paul

    2012-01-01

    Negotiation of language form is thought to engage learning processes by helping learners to notice gaps in their developing L2 and find target-like ways of filling them. Self-transcription, where learners work together to find language errors in recordings of their own oral output, is an awareness raising exercise that encourages such negotiation.…

  14. Effects and Student Perceptions of Collaborative Writing in L2

    Science.gov (United States)

    Shehadeh, Ali

    2011-01-01

    This study investigated the effectiveness and students' perceptions of collaborative writing (CW) in second language (L2). The study involved 38 first year students in two intact classes at a large university in the UAE (United Arab Emirates). One class consisted of 18 students and was considered the experimental group, and the second consisted of…

  15. The Role of Individual Differences in L2 Writing

    Science.gov (United States)

    Kormos, Judit

    2012-01-01

    Although the role of individual differences in second language (L2) speech has been extensively studied, the impact of individual differences on the process of second language writing and the written product has been a neglected area of research. In this paper, I review the most important individual difference factors that might explain variations…

  16. PEER REVISION OF WRITING IN L2 CLASSROOM

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Peer revision,a supplementary strategy to teacher revisionof writing in L2 classroom,makes passive receivers of teacherrevision become active revisers,enabling students to involve inmore motivated language learning.Benefits of peer revision andits implications for teacher and student roles are discussed.Thisarticle also tentatively analyzes ways of preparing students foreffective peer revision.

  17. The Teaching of L2 Pronunciation through Processing Instruction

    Science.gov (United States)

    Gonzales-Bueno, Manuela; Quintana-Lara, Marcela

    2011-01-01

    The goal of this study is to pilot test whether the instructional approach known as Processing Instruction could be adapted to the teaching of second language (L2) pronunciation. The target sounds selected were the Spanish tap and trill. Three groups of high school students of Spanish as a foreign language participated in the study. One group…

  18. The Effectiveness of L2 Pronunciation Instruction: A Narrative Review

    Science.gov (United States)

    Thomson, Ron I.; Derwing, Tracey M.

    2015-01-01

    Research on the efficacy of second language (L2) pronunciation instruction has produced mixed results, despite reports of significant improvement in many studies. Possible explanations for divergent outcomes include learner individual differences, goals and foci of instruction, type and duration of instructional input, and assessment procedures.…

  19. Affective Variables and Japanese L2 Reading Ability

    Science.gov (United States)

    Kondo-Brown, Kimi

    2006-01-01

    This study investigates how 17 affective factors are related to Japanese second language (L2) reading comprehension and "kanji" knowledge test scores of 43 university students in advanced Japanese courses. Major findings are that: a) reading comprehension ability and "kanji" knowledge have direct associations with…

  20. The Analysis of L2 Learners'Fossilization in Interlanguage

    Institute of Scientific and Technical Information of China (English)

    赵冰

    2008-01-01

    The author designed a questionnaire,emailed and interviewed thirty advanced L2 learners who work as L2 lecturers in a university to get a survey on the processing of fossilization in their foreign language learning and teaching from the causes of purpose of learning.teaching tasks and other factors involved.AU of the subjects thought that their coinlnand of the target language was not as good as a native speaker's of target language in many aspects.That is.there existed fossilization among them.However,most of them agreed that their command of the target language was adequate for their professional and communication needs.Results also suggest that fossilization Can be conscious to this group of L2 learners;it is deeply related with the L2 learners'motivations;it can be affected by personal famres such as ages,learning styles and teaching tasks;it is changeable and unpredictable;and jt is diffcult to eradicate.

  1. Epilogue: Exploring L2 Writing-SLA Interfaces

    Science.gov (United States)

    Ortega, Lourdes

    2012-01-01

    In this closing commentary, I first briefly recognize areas that have made the dialogue between the fields of second language (L2) writing and second language acquisition (SLA) difficult in the past. I then offer some comments on the interfaces that are brought to the fore by the contributions gathered in the special issue. The themes explored are…

  2. L2 Reading Motivation among Sri Lankan University Students

    Science.gov (United States)

    Dhanapala, Kusumi Vasantha; Hirakawa, Yukiko

    2016-01-01

    This study investigated the extent of the motivational processes that facilitated the text comprehension among 406 Sri Lankan university students in Sri Lanka. Students' L2 text comprehension and reading motivation were assessed using a reading comprehension test and a reading motivation and attitude questionnaire. The Principal Componential…

  3. Grammar Teaching and Learning in L2: Necessary, but Boring?

    Science.gov (United States)

    Jean, Gladys; Simard, Daphnee

    2011-01-01

    This descriptive inquiry-based study targeted second language (L2) high school students' (n = 2321) and teachers' (n = 45) beliefs and perceptions about grammar instruction, specifically about grammatical accuracy, corrective feedback, and diverse forms of grammar teaching and learning. Results showed only slight discrepancies between students'…

  4. L1-L2 Sentence Translation in Classroom Grammar Tests

    Science.gov (United States)

    Salem, Ilana

    2012-01-01

    L1-L2 translation of separate sentences is one kind of task format used by mainstream EFL teachers to assess their learners' grammatical accuracy. Aimed at improving teacher-written translation items, this study analyses linguistic features potentially causing such decontextualized cues (and their target responses) to sound odd or untypical of…

  5. Memorization versus Semantic Mapping in L2 Vocabulary Acquisition

    Science.gov (United States)

    Khoii, Roya; Sharififar, Samira

    2013-01-01

    This study investigated the effects of two cognitive strategies, rote memorization and semantic mapping, on L2 vocabulary acquisition. Thirty-eight intermediate female EFL learners divided into two experimental groups participated in this study. Each experimental group used one of the strategies for vocabulary acquisition. After the four-month…

  6. Lexical Bundles in L1 and L2 Academic Writing

    Science.gov (United States)

    Chen, Yu-Hua; Baker, Paul

    2010-01-01

    This paper adopts an automated frequency-driven approach to identify frequently-used word combinations (i.e., "lexical bundles") in academic writing. Lexical bundles retrieved from one corpus of published academic texts and two corpora of student academic writing (one L1, the other L2), were investigated both quantitatively and qualitatively.…

  7. Using Turnitin to Provide Feedback on L2 Writers' Texts

    Science.gov (United States)

    Kostka, Ilka; Maliborska, Veronika

    2016-01-01

    Second language (L2) writing instructors have varying tools at their disposal for providing feedback on students' writing, including ones that enable them to provide written and audio feedback in electronic form. One tool that has been underexplored is Turnitin, a widely used software program that matches electronic text to a wide range of…

  8. Communicative adequacy and linguistic complexity in L2 writing

    NARCIS (Netherlands)

    F. Kuiken; I. Vedder; R. Gilabert

    2010-01-01

    The chapter investigates the relationship between communicative adequacy and linguistic complexity (syntactic complexity, lexical diversity, accuracy) of the written output of L2 writers of Dutch, Italian and Spanish. The main goal of the CALC study (‘Communicative Adequacy and Linguistic Complexity

  9. Developing Intentionality and L2 Classroom Task-Engagement

    Science.gov (United States)

    Stelma, Juup

    2014-01-01

    This paper extends work on "intentionality", from philosophy, psychology and education to an exploration of learners' meaning-making in L2 classroom task-engagement. The paper draws on both phenomenological and folk-psychological perspectives on intentionality, and employs John R. Searle's intrinsic (mental) and derived (observable)…

  10. Epilogue: Exploring L2 Writing-SLA Interfaces

    Science.gov (United States)

    Ortega, Lourdes

    2012-01-01

    In this closing commentary, I first briefly recognize areas that have made the dialogue between the fields of second language (L2) writing and second language acquisition (SLA) difficult in the past. I then offer some comments on the interfaces that are brought to the fore by the contributions gathered in the special issue. The themes explored are…

  11. Grammar Teaching and Learning in L2: Necessary, but Boring?

    Science.gov (United States)

    Jean, Gladys; Simard, Daphnee

    2011-01-01

    This descriptive inquiry-based study targeted second language (L2) high school students' (n = 2321) and teachers' (n = 45) beliefs and perceptions about grammar instruction, specifically about grammatical accuracy, corrective feedback, and diverse forms of grammar teaching and learning. Results showed only slight discrepancies between students'…

  12. Young L2 learners' performance on a novel morpheme task.

    Science.gov (United States)

    Kohnert, Kathryn; Danahy, Kerry

    2007-07-01

    The teaching of an invented language rule has been proposed as a possible non-biased, language-independent assessment technique useful in differentiating young L2 learners with specific language impairment from their typically developing peers. The current study explores these notions by testing typically developing sequential bilingual children's ability to learn an invented language rule in either L1 (Spanish) or L2 (English). Participants were 20 children, age 3:6-5:8, who attended a Head Start programme. For all children, Spanish was the primary language spoken in the home and English was the primary language of instruction. Children were randomly assigned two groups. Group L1 was taught the novel language rule in Spanish; Group L2 was taught the novel language rule in English. Performance was better for the L1 group than for the L2 group. Moreover, not all of these typical language learners were able to learn the new rule, even in their strongest language. These findings suggest that even for typically developing children, specific language proficiency as well as individual differences are closely linked to performance on this novel morpheme learning task.

  13. Posters, Self-Directed Learning, and L2 Vocabulary Acquisition

    Science.gov (United States)

    Cetin, Yakup; Flamand, Lee

    2013-01-01

    Posters, either as promotions by various ELT publishing houses or prepared by ELT teachers and students, are widely used on the walls of many foreign language classrooms. Many of them consist of colourful pictures along with L2 vocabulary, grammar, and texts in order to contribute to the foreign language learning process. However, many ELT…

  14. New Perspectives on Multilingualism and L2 Acquisition: An Introduction

    Science.gov (United States)

    de Zarobe, Leyre Ruiz; de Zarobe, Yolanda Ruiz

    2015-01-01

    This article focuses on the description of one of the main features of current multilingualism, complexity, through a selection of issues related to its role in L2 acquisition, as the proper notion of multilingualism, multilingualism as a social phenomenon and multilingualism as a multidimensional phenomenon. We also present several aspects of…

  15. The Laplace transform and polynomial approximation in L2

    DEFF Research Database (Denmark)

    Labouriau, Rodrigo

    2016-01-01

    in play is bounded in a neighbourhood of the origin, then the moments of all order are finite and the class of polynomials is dense in L2. The existence of the moments of all orders is well known for the case where the measure is concentrated in the positive real line (see Feller, 1966), but the result...

  16. Young L2 Learners' Performance on a Novel Morpheme Task

    Science.gov (United States)

    Kohnert, Kathryn; Danahy, Kerry

    2007-01-01

    The teaching of an invented language rule has been proposed as a possible non-biased, language-independent assessment technique useful in differentiating young L2 learners with specific language impairment from their typically developing peers. The current study explores these notions by testing typically developing sequential bilingual children's…

  17. Implicit Learning of L2 Word Stress Regularities

    Science.gov (United States)

    Chan, Ricky K. W.; Leung, Janny H. C.

    2014-01-01

    This article reports an experiment on the implicit learning of second language stress regularities, and presents a methodological innovation on awareness measurement. After practising two-syllable Spanish words, native Cantonese speakers with English as a second language (L2) completed a judgement task. Critical items differed only in placement of…

  18. L2 English Listening:A Metacognitive Approach

    Institute of Scientific and Technical Information of China (English)

    于红霞

    2014-01-01

    Metacognitive instruction is considered to be an effective approach of teaching listening in L2 context. Related research reports positively about the relation between listening performance and metacognitive instruction. However, when implementing metacognitive instruction in English classrooms in the context of China, there are some aspects deserving our further discussion.

  19. L2 Reading Motivation among Sri Lankan University Students

    Science.gov (United States)

    Dhanapala, Kusumi Vasantha; Hirakawa, Yukiko

    2016-01-01

    This study investigated the extent of the motivational processes that facilitated the text comprehension among 406 Sri Lankan university students in Sri Lanka. Students' L2 text comprehension and reading motivation were assessed using a reading comprehension test and a reading motivation and attitude questionnaire. The Principal Componential…

  20. Hedging, Inflating, and Persuading in L2 Academic Writing

    Science.gov (United States)

    Hinkel, Eli

    2005-01-01

    This study analyzes the types and frequencies of hedges and intensifiers employed in NS and NNS academic essays included in a corpus of L1 and L2 student academic texts (745 essays/220,747 words). The overarching goal of this investigation is to focus on these lexical and syntactic features of written discourse because they effectively lend…

  1. (T2L2) Time Transfer by Laser Link

    Science.gov (United States)

    Veillet, Christian; Fridelance, Patricia

    1995-05-01

    T2L2 (Time Transfer by Laser Link) is a new generation time transfer experiment based on the principles of LASSO (Laser Synchronization from Synchronous Orbit) and used with an operational procedure developed at OCA (Observatoire de la Cote d'Azur) during the active intercontinental phase of LASSO. The hardware improvements could lead to a precision better than 10 ps for time transfer (flying clock monitoring or ground based clock comparison). Such a package could fly on any spacecraft with a stable clock. It has been developed in France in the frame of the PHARAO project (cooled atom clock in orbit) involving CNES and different laboratories. But T2L2 could fly on any spacecraft carrying a stable oscillator. A GPS satellite would be a good candidate, as T2L2 could allow to link the flying clock directly to ground clocks using light, aiming to important accuracy checks, both for time and for geodesy. Radioastron (a flying VLBI antenna with a H-maser) is also envisioned, waiting for a PHARAO flight. The ultimate goal of T2L2 is to be part of more ambitious missions, as SORT (Solar Orbit Relativity Test), aiming to examine aspects of the gravitation in the vicinity of the Sun.

  2. Sociocultural Theory and L2: State of the Art

    Science.gov (United States)

    Lantolf, James P.

    2006-01-01

    This article considers the implications of two central constructs of sociocultural theory (SCT) for second language (L2) development: mediation and internalization. It first discusses Vygotsky's general theoretical claim that human mental activity arises as a consequence of the functional system formed by our biologically specified mental…

  3. Effect of Alignment on L2 Written Production

    Science.gov (United States)

    Wang, Chuming; Wang, Min

    2015-01-01

    This article aims to uncover how L2 writing is affected by alignment, a socio-cognitive process involving dynamic coordination and adaptation. For this, two studies were conducted. Study 1 required two groups of 24 learners of English as a foreign language (EFL) to continue in English two stories with their endings removed, both of which had a…

  4. L2-Accented Speech in L3 Production

    Science.gov (United States)

    Wrembel, Magdalena

    2010-01-01

    The paper is aimed at investigating the sources of cross-linguistic influence in the third language (L3) phonology, and, particularly, the impact of the second language (L2) on the phonological acquisition of another foreign language. The study consisted in foreign accent judgements performed by a group of expert judges who were presented with…

  5. New Perspectives on Multilingualism and L2 Acquisition: An Introduction

    Science.gov (United States)

    de Zarobe, Leyre Ruiz; de Zarobe, Yolanda Ruiz

    2015-01-01

    This article focuses on the description of one of the main features of current multilingualism, complexity, through a selection of issues related to its role in L2 acquisition, as the proper notion of multilingualism, multilingualism as a social phenomenon and multilingualism as a multidimensional phenomenon. We also present several aspects of…

  6. Strategic Processing and Predictive Inference Generation in L2 Reading

    Science.gov (United States)

    Nahatame, Shingo

    2014-01-01

    Predictive inference is the anticipation of the likely consequences of events described in a text. This study investigated predictive inference generation during second language (L2) reading, with a focus on the effects of strategy instructions. In this experiment, Japanese university students read several short narrative passages designed to…

  7. Influence of musical training on perception of L2 speech

    NARCIS (Netherlands)

    Sadakata, M.; Zanden, L.D.T. van der; Sekiyama, K.

    2010-01-01

    The current study reports specific cases in which a positive transfer of perceptual ability from the music domain to the language domain occurs. We tested whether musical training enhances discrimination and identification performance of L2 speech sounds (timing features, nasal consonants and vowels

  8. Deconstructing Gender Stereotyping through Literature in L2

    Science.gov (United States)

    Yulita, Leticia

    2010-01-01

    While it is generally accepted that literature fosters (inter)cultural learning, few qualitative studies have sought to understand in what ways interculturality is developed. This article investigates the development of Spanish L2 students' intercultural awareness through the reading of a short story entitled "Norma y Ester" by Argentine…

  9. Phonetics Instruction Improves Learners' Perception of L2 Sounds

    Science.gov (United States)

    Kissling, Elizabeth M.

    2015-01-01

    Explicit phonetics instruction can help second language (L2) learners to moderately improve their pronunciation, but less is known about how the instruction affects learners' perception, even though there is evidence that perception and pronunciation are related. This study provided phonetics instruction to students (n = 46) studying Spanish as a…

  10. Teaching L2 Pragmatics: Opportunities for Continuing Professional Development

    Science.gov (United States)

    Vellenga, Heidi

    2011-01-01

    Teaching L2 pragmatics is often not covered in teacher education programs, and is an excellent area for continuing professional development. As part of a larger project on instructed interlanguage pragmatics, volunteer instructor participants were asked to teach a series of lessons on pragmatics to university-aged (19-23) ESL learners in ESL and…

  11. L2-Accented Speech in L3 Production

    Science.gov (United States)

    Wrembel, Magdalena

    2010-01-01

    The paper is aimed at investigating the sources of cross-linguistic influence in the third language (L3) phonology, and, particularly, the impact of the second language (L2) on the phonological acquisition of another foreign language. The study consisted in foreign accent judgements performed by a group of expert judges who were presented with…

  12. Influence of Syllable Structure on L2 Auditory Word Learning

    Science.gov (United States)

    Hamada, Megumi; Goya, Hideki

    2015-01-01

    This study investigated the role of syllable structure in L2 auditory word learning. Based on research on cross-linguistic variation of speech perception and lexical memory, it was hypothesized that Japanese L1 learners of English would learn English words with an open-syllable structure without consonant clusters better than words with a…

  13. Lexical Bundles in L1 and L2 Academic Writing

    Science.gov (United States)

    Chen, Yu-Hua; Baker, Paul

    2010-01-01

    This paper adopts an automated frequency-driven approach to identify frequently-used word combinations (i.e., "lexical bundles") in academic writing. Lexical bundles retrieved from one corpus of published academic texts and two corpora of student academic writing (one L1, the other L2), were investigated both quantitatively and qualitatively.…

  14. Developing Intentionality and L2 Classroom Task-Engagement

    Science.gov (United States)

    Stelma, Juup

    2014-01-01

    This paper extends work on "intentionality", from philosophy, psychology and education to an exploration of learners' meaning-making in L2 classroom task-engagement. The paper draws on both phenomenological and folk-psychological perspectives on intentionality, and employs John R. Searle's intrinsic (mental) and derived (observable)…

  15. Institutional Forces and L2 Writing Feedback in Higher Education

    Science.gov (United States)

    Seror, Jeremie

    2009-01-01

    There has recently been growing interest in the relationship between second language (L2) writing development and the institutional contexts in which this process is embedded. The present study examines this relationship by reporting on an eight-month qualitative investigation of international university students and their perspectives on the…

  16. Facebook Activities and the Investment of L2 Learners

    Science.gov (United States)

    Shafie, Latisha Asmaak; Yaacob, Aizan; Singh, Paramjit Kaur Karpal

    2016-01-01

    The article discusses the investment of L2 learners in the English language on Facebook that they portrayed through their Facebook activities. It studied four informants consisted of diploma students in a Malaysian university. The study consisted of 14 weeks of online observation and semi-structured interviews. Data were collected from online…

  17. Collaborative Revision in L2 Writing: Learners' Reflections

    Science.gov (United States)

    Memari Hanjani, Alireza

    2016-01-01

    L2 learning literature has reflected on the problems surrounding the application of teacher written feedback and peer feedback in EFL contexts. To address the disadvantages of these feedback forms, this exploratory case study examined EFL learners' reactions to a collaborative revision activity. Interview data were collected from eight native…

  18. Lexical Aspects of Very Advanced L2 French

    Science.gov (United States)

    Lundell, Fanny Forsberg; Lindqvist, Christina

    2014-01-01

    The present study investigates the possibilities for adult learners to attain nativelikeness in the domain of lexis. Aspects investigated are general lexical knowledge (C-test), receptive deep knowledge, productive collocation knowledge, and productive lexico-pragmatic knowledge in a group of long-residency Swedish French second language (L2)…

  19. Posters, Self-Directed Learning, and L2 Vocabulary Acquisition

    Science.gov (United States)

    Cetin, Yakup; Flamand, Lee

    2013-01-01

    Posters, either as promotions by various ELT publishing houses or prepared by ELT teachers and students, are widely used on the walls of many foreign language classrooms. Many of them consist of colourful pictures along with L2 vocabulary, grammar, and texts in order to contribute to the foreign language learning process. However, many ELT…

  20. LA DIDATTICA DELL’ITALIANO L2 A DETENUTI STRANIERI

    Directory of Open Access Journals (Sweden)

    Valentina Bonfanti

    2012-07-01

    Full Text Available L’insegnamento dell’italiano L2 all’interno degli istituti penitenziari è diventata un’esigenza fondamentale, data la crescente presenza di detenuti stranieri nelle strutture detentive del nostro Paese.Il presente lavoro analizza le peculiarità dell’insegnamento dell’italiano L2 a detenuti stranieri: ruolo e caratteristiche del docente, bisogni e motivazioni dell’apprendente, problematiche legate al contesto specifico di apprendimento. In particolare si intende mettere in evidenza il ruolo primario della scrittura come mezzo fondamentale per svolgere attività quotidiane (padroneggiare regolamenti, richieste, “domandine” e come strumento per la rieducazione.Per meglio comprendere le specificità dell’insegnamento in questo contesto, viene presentato un sillabo per apprendenti detenuti redatto da Antonella Benucci ed in appendice due interviste rivolte a docenti della Casa Circondariale di Monza.TEACHING ITALIAN L2 TO FOREIGN INMATESTeaching Italian L2 in prisons has become a basic need, given the growing number of foreign detainees in Italian prisons.This paper analyzes the peculiarity of teaching Italian L2 to foreign inmates: the teacher’s role and characteristics, the student’s needs and motivations, problems linked to the specific setting. We highlight the primary role of writing as a fundamental means for carrying out daily activities (mastering rules, requests, “small questions” and as a re-education tool.To better understand the specificity of teaching in this context, a syllabus for detainees compiled by Antonella Benucci is presented and there are two interviews with teachers working in a prison in Monza.

  1. New approaches to robust l2-l∞ and H∞ filtering for uncertain discrete-time systems

    Institute of Scientific and Technical Information of China (English)

    高会军; 王常虹

    2003-01-01

    The problems of robust l2-l∞ and H∞ filtering for discrete-time systems with parameter uncer- tainty residing in a polytope are investigated in this paper. The filtering strategies are based on new ro- bust performance criteria derived from a new result of parameter-dependent Lyapunov stability condition, which exhibit less conservativeness than previous results in the quadratic framework. The designed filters guaranteeing a prescribed l2-l∞ or H∞ noise attenuation level can be obtained from the solution of convex optimization problems, which can be solved via efficient interior point methods. Numerical examples have shown that the filter design procedures proposed in this paper are much less conservative than earlier results.

  2. Learning Second Language Suprasegmentals: Effect of L2 Experience on Prosody and Fluency Characteristics of L2 Speech

    Science.gov (United States)

    Trofimovich, Pavel; Baker, Wendy

    2006-01-01

    This study examines effects of short, medium, and extended second language (L2) experience (3 months, 3 years, and 10 years of United States residence, respectively) on the production of five suprasegmentals (stress timing, peak alignment, speech rate, pause frequency, and pause duration) in six English declarative sentences by 30 adult Korean…

  3. Relationship of L1 Skills and L2 Aptitude to L2 Anxiety on the Foreign Language Classroom Anxiety Scale

    Science.gov (United States)

    Sparks, Richard L.; Patton, Jon

    2013-01-01

    The Foreign Language Classroom Anxiety Scale (FLCAS) has been challenged on the grounds that it may also assess language learning skills. In this study, 128 students who had been administered measures of first language (L1) skills in elementary school were followed from 1st to 10th grade. Fifty-three students had completed second language (L2)…

  4. Tracing trajectories: motion event construal by advanced L2 French-English and L2 French-German speakers

    NARCIS (Netherlands)

    Carroll, M.; Weimar, K.; Flecken, M.E.P.; Lambert, M.; Stutterheim, C. von

    2012-01-01

    Although the typological contrast between Romance and Germanic languages as verb-framed versus satellite-framed (Talmy 1985) forms the background for many empirical studies on L2 acquisition, the inconclusive picture to date calls for more differentiated, fine-grained analyses. The present study goe

  5. How stressful is L2 stress? A cross-linguistic study of L2 perception and production of metrical systems

    NARCIS (Netherlands)

    Kijak, A.M.

    2009-01-01

    This dissertation addresses the second language (L2) acquisition of word stress in production and perception, from both a phonological-theoretical and psycholinguistic angle. It investigates how cross-linguistic differences in the (types of) metrical systems of native speakers of a variety of first

  6. Sub-ns time transfer consistency: a direct comparison between GPS CV and T2L2

    Science.gov (United States)

    Exertier, P.; Samain, E.; Courde, C.; Aimar, M.; Torre, J. M.; Rovera, G. D.; Abgrall, M.; Uhrich, P.; Sherwood, R.; Herold, G.; Schreiber, U.; Guillemot, P.

    2016-12-01

    This paper presents a direct comparison between two satellite time transfer techniques: common-view (CV) of satellites from the global positioning system (GPS) constellation, and time transfer by laser link (T2L2) through the low orbiting satellite Jason-2. We describe briefly both techniques, together with two independent relative calibration campaigns of the links involving four European laboratories. Between the same remote time scale reference points, the mean values of the calibrated differences between GPS CV and T2L2 are below 240 ps, with standard deviations below 500 ps, mostly due to GPS CV. Almost all sample deviations from 0 ns are within the combined uncertainty estimates. Despite the relatively small number of common points obtained, due to the fact that T2L2 is weather dependent, these results provide an unprecedented sub-ns consistency between two independently calibrated microwave and optical satellite time transfer techniques.

  7. Lexical Inference in L2: Predictive Roles of Vocabulary Knowledge and Reading Skill beyond Reading Comprehension

    Science.gov (United States)

    Prior, Anat; Goldina, Anna; Shany, Michal; Geva, Esther; Katzir, Tami

    2014-01-01

    The current study examined the predictive roles of L2 vocabulary knowledge and L2 word reading skills in explaining individual differences in lexical inferencing in the L2. Participants were 53 Israeli high school students who emigrated from the former Soviet Union, and spoke Russian as an L1 and Hebrew as an L2. L2 vocabulary knowledge and…

  8. ALLOPHONIC SPLITS IN L2 PHONOLOGY: THE QUESTION OF LEARNABILITY

    Directory of Open Access Journals (Sweden)

    Gregory K . Iverson

    2001-06-01

    Full Text Available The research reported in this paper is intended as a contribution to the understanding of several wellknown problems relating to the leaming of phonemic contrasts in second language (L2 phonology. The paper describes a series of ongoing studies examining what Lado (1957 hypothesized to represent maximum diffículty in second language pronunciation, narnely, a phonemic split. This is the process involved when an L2 learner must split native language (NL allophones into separate target language (TL phonemes. Two core principles of phonological theory are described and evaluated for their relevante in explaining the series of well-defined, implicationally-related stages involved in a phonemic split. Finally, the paper reports the results of an empirical study designed to test the explanatory adequacy of these principles, and concludes with a discussion of the implications of these studies for second language phonology in general.

  9. Optimally weighted L(2) distance for functional data.

    Science.gov (United States)

    Chen, Huaihou; Reiss, Philip T; Tarpey, Thaddeus

    2014-09-01

    Many techniques of functional data analysis require choosing a measure of distance between functions, with the most common choice being L2 distance. In this article we show that using a weighted L2 distance, with a judiciously chosen weight function, can improve the performance of various statistical methods for functional data, including k-medoids clustering, nonparametric classification, and permutation testing. Assuming a quadratically penalized (e.g., spline) basis representation for the functional data, we consider three nontrivial weight functions: design density weights, inverse-variance weights, and a new weight function that minimizes the coefficient of variation of the resulting squared distance by means of an efficient iterative procedure. The benefits of weighting, in particular with the proposed weight function, are demonstrated both in simulation studies and in applications to the Berkeley growth data and a functional magnetic resonance imaging data set.

  10. Literary Language in Development of L2 Competence

    Directory of Open Access Journals (Sweden)

    Dan Lu

    2012-11-01

    Full Text Available Nowadays it is believed that language in daily communication rather than literary language should be the target of learning in L2 education. This is mainly because literary language is said to be uncommon in life. This paper reports on a study in which some Hong Kong ESL learners’ English proficiency was re-examined through literary texts. These learners had reached intermediate or advanced levels of English prior to the study and were generally competent in daily English. However, many of them encountered difficulty in understanding literary language. Their proficiency in general English test could not match their performances in understanding literary works. The findings reveal that learners who are strong in general proficiency may not be good in understanding literary language. Lack of literary language in the curriculum results in a false and distorted picture about the learners’ proficiency. Literary language helps upgrade L2 learners’ real proficiency in the target language.

  11. Object Tracking via 2DPCA and l2-Regularization

    Directory of Open Access Journals (Sweden)

    Haijun Wang

    2016-01-01

    Full Text Available We present a fast and robust object tracking algorithm by using 2DPCA and l2-regularization in a Bayesian inference framework. Firstly, we model the challenging appearance of the tracked object using 2DPCA bases, which exploit the strength of subspace representation. Secondly, we adopt the l2-regularization to solve the proposed presentation model and remove the trivial templates from the sparse tracking method which can provide a more fast tracking performance. Finally, we present a novel likelihood function that considers the reconstruction error, which is concluded from the orthogonal left-projection matrix and the orthogonal right-projection matrix. Experimental results on several challenging image sequences demonstrate that the proposed method can achieve more favorable performance against state-of-the-art tracking algorithms.

  12. IL WORKSHOP DI FONETICA IN ITALIANO L2/LS

    Directory of Open Access Journals (Sweden)

    Lidia Calabrò

    2015-07-01

    Full Text Available Lavorare sugli aspetti fonetico-fonologici di una lingua straniera sembra essere ritenuta un’impresa abbastanza ardua da parte dei docenti e un lavoro faticosissimo da parte degli apprendenti. Attraverso un’esperienza iniziata con studenti lusofoni del brasile si vuole presentare il workshop di fonetica nell’italiano L2 come proposta di didattica integrativa al fine di sensibilizzare gli studenti ai tratti segmentali e soprasegmentali della L2 a contrasto con quelli della loro L1. Nel presente contributo verranno presentate alcune attività riguardanti la percezione e l’articolazione dei suoni vocalici, la tecnica della proprioception e la presentazione della tabella fonemica per le vocali, le trascrizioni fonetiche e la durata vocalica in sillaba accentata. Tutte le attività prevedono un coinvolgimento personale e totale del singolo apprendente e di tutta la classe in quanto il workshop si avvale di multimodalità, multimedialità e apprendimento collaborativo al fine di scoprire i suoni della L2 e riflettere sulla loro percezione e articolazione.Italian L2/FL phonetic workshopsSecond language phonetics and phonological aspects are considered difficult to teach and learn by teachers and learners respectively. Based on a teaching experience with Brazilian students, this paper aims at presenting phonetic workshops in Italian as a second language to raise consciousness in students about the FL segmental and suprasegmental aspects in contrast to those of their L1. Some activities related to Italian vowels will be presented: perception and articulation, the proprioception technique and the phonemic chart, phonetic transcriptions and vowel length in stressed syllables. The activities involve the students in a more personal, total and physical way in collaboration with their classmates. The workshop designed as multimodal, multimedia and cooperative, aiming at discovering the sounds of the FL and reflecting on the perception and articulation

  13. Feedback in L2 writing: the students' perspective

    OpenAIRE

    Vokic, Gabriela

    2008-01-01

    Given the disparate views in L2 writing literature on what constitutes effective teacher feedback, this qualitative study approached this issue from the student???s perspective. In order to examine what constitutes effective teacher feedback from the student???s standpoint, fifty-four student responses to three drastically different feedback styles were analyzed. The results of this preliminary study are partially in line with Hyland (1998), since it was found that whethe...

  14. L2 Quality as a Competitive Edge - Project Presentation

    DEFF Research Database (Denmark)

    Ditlevsen, Marianne Grove; Kastberg, Peter

    2000-01-01

    In our paper we would like to present an interdisciplinary project "L2 as a Competitive Edge". We'll be doing this by first giving you a project overview in section 0. The overview will then in the section 1 and 2 be followed by a presentation of two of the most interesting themes, serving as poi...... of departure for further discussion. The two themes are "The evaluation of language quality" and "Method - an Integrated Approach"....

  15. Effects of sentence context in L2 natural speech comprehension

    OpenAIRE

    Fitzpatrick, I.

    2007-01-01

    Electrophysiological studies consistently find N400 effects of semantic incongruity in non-native written language comprehension. Typically these N400 effects are later than N400 effects in native comprehension, suggesting that semantic processing in one’s second language (L2) may be delayed compared to one’s first language (L1). In this study we were firstly interested in replicating the semantic incongruity effect using natural auditory speech, which poses strong demands on the speed of pro...

  16. CLASSIFICATION OF L2 WRITING PROCESS AND WRITING STRATEGIES

    OpenAIRE

    Abas, Imelda Hermilinda; Aziz, Noor Hashima Abd

    2017-01-01

    English for second language writing has developed greatly, from product oriented approach to process oriented approach. This implies that the focus of L2 writing has shifted from the final product of writing to the process of writing. Because of its own rules and conventions, writing skill is considered difficult to learn in a short period of time. Although it is a difficult skill, writing is essential for second language learners’ academic success. Second language researchers are still tryin...

  17. T2L2 - Time Transfer by Laser Link

    Science.gov (United States)

    Weick, J.; Samain, E.; Bério, Ph.

    2005-12-01

    T2L2 is an experiment based on laser ranging technique coupled with time-frequency metrology. The goal consists in synchronizing ground and space clocks using short light pulses travelling between the ground and a satellite. The instrument will be integrated to the Jason-2 altimetric satellite launched in 2008. The experiment should enhance the performances of time transfert by one or two magnitudes compared to existing microwave techniques like GPS and Two-Way.

  18. Acquisition of L2 Japanese Geminates: Training with Waveform Displays

    Science.gov (United States)

    Motohashi-Saigo, Miki; Hardison, Debra M.

    2009-01-01

    The value of waveform displays as visual feedback was explored in a training study involving perception and production of L2 Japanese by beginning-level L1 English learners. A pretest-posttest design compared auditory-visual (AV) and auditory-only (A-only) Web-based training. Stimuli were singleton and geminate /t,k,s/ followed by /a,u/ in two…

  19. The new type 2 diabetes gene TCF7L2.

    Science.gov (United States)

    Florez, Jose C

    2007-07-01

    Common variants in the gene that encodes the transcription factor 7-like 2 (TCF7L2) have been strongly associated with type 2 diabetes. This highly reproducible association may uncover novel mechanisms of glycemic pathophysiology. The initial publication of an association of common variants in TCF7L2 with type 2 diabetes in people of European descent has been followed by an avalanche of replication reports. These papers not only confirm the original finding, but also extend it to other populations, fine map the source of the association signal, describe its effect on metabolic parameters in humans, open the door to a more precise molecular characterization, and provide an insight into its possible impact on diabetes therapy. The discovery of TCF7L2 as a diabetes gene illustrates that novel true diabetes genes can be found, their association with type 2 diabetes replicated and their effect incorporated into risk prediction models. It is hoped that the detection of other such genes in genome-wide association scans will help elucidate the genetic architecture of this disease.

  20. CONSIDERAZIONI SULLA DIDATTICA DELL’ITALIANO L2 IN SVIZZERA

    Directory of Open Access Journals (Sweden)

    Elena Maria Pandolfi

    2010-09-01

    Full Text Available L'articolo propone alcune considerazioni sulla didattica dell'italiano come L2 in Svizzera, partendo da una breve disamina della posizione che l'italiano ha in Svizzera all'interno del suo territorio e nei Cantoni non italofoni. Si è dunque trattato della didattica dell'italiano L2 in Svizzera abbozzando i tratti principali che caratterizzano la didattica fuori e all'interno del territorio italofono. Si è anche proposta una lista di alcuni lessemi marcati in diatopia che caratterizzano l'italiano in Svizzera, sottolineando come questi e altri tratti più squisitamente sociolinguistici possano indurre a considerare anche l'italiano come una lingua pluricentrica, con le implicazioni che questo concetto ha per la didattica dell'italiano L2 in Svizzera, anche dal punto di vista della riflessione metalinguistica.   The paper proposes some considerations concerning teaching Italian as a second language in Switzerland. Through a brief description of the position of Italian inside the Swiss quadrilingualism the teaching approaches are discussed taking into account the peculiar situation inside and outside the Italian territory. Besides the paper presents a list of some common lexemes diatopically marked inducing, along with sociolinguistic parameters, at considering Italian as a pluricentric language with the implication the concept may have concerning the teaching of Italian as a second language in Switzerland.

  1. L2 OSTC-CPM: Theory and design

    CERN Document Server

    Hesse, Matthias; Deneire, Luc

    2008-01-01

    The combination of space-time coding (STC) and continuous phase modulation (CPM) is an attractive field of research because both STC and CPM bring many advantages for wireless communications. Zhang and Fitz [1] were the first to apply this idea by constructing a trellis based scheme. But for these codes the decoding effort grows exponentially with the number of transmitting antennas. This was circumvented by orthogonal codes introduced by Wang and Xia [2]. Unfortunately, based on Alamouti code [3], this design is restricted to two antennas. However, by relaxing the orthogonality condition, we prove here that it is possible to design L2-orthogonal space-time codes which achieve full rate and full diversity with low decoding effort. In part one, we generalize the two-antenna code proposed by Wang and Xia [2] from pointwise to L2-orthogonality and in part two we present the first L2-orthogonal code for CPM with three antennas. In this report, we detail these results and focus on the properties of these codes. Of...

  2. Accounting for L2 learners’ errors in word stress placement

    Directory of Open Access Journals (Sweden)

    Clara Herlina Karjo

    2016-01-01

    Full Text Available Stress placement in English words is governed by highly complicated rules. Thus, assigning stress correctly in English words has been a challenging task for L2 learners, especially Indonesian learners since their L1 does not recognize such stress system. This study explores the production of English word stress by 30 university students. The method used for this study is immediate repetition task. Participants are instructed to identify the stress placement of 80 English words which are auditorily presented as stimuli and immediately repeat the words with correct stress placement. The objectives of this study are to find out whether English word stress placement is problematic for L2 learners and to investigate the phonological factors which account for these problems. Research reveals that L2 learners have different ability in producing the stress, but three-syllable words are more problematic than two-syllable words. Moreover, misplacement of stress is caused by, among others, the influence of vowel lenght and vowel height.

  3. Three-dimensional hydrodynamic simulations of L2 Puppis

    CERN Document Server

    Chen, Zhuo; Frank, Adam; Blackman, Eric G

    2016-01-01

    Recent observations of the L2 Puppis system suggest that the Mira-like variable may be in the early stages of forming a bipolar planetary nebula (PN). As one of nearest and brightest AGB stars, and due to its status as a binary, L2 Puppis serves as a benchmark object for studying the late-stages of stellar evolution. We perform global, three-dimensional, adaptive-mesh-refinement hydrodynamic simulations of the L2 Puppis system with AstroBEAR. The broad-band spectral-energy-distribution (SED) and synthetic observational images are post-processed from our simulations using the radiative transfer code RADMC-3D. Given the reported binary parameters, we are able to reproduce the current observational data if a short pulse of dense material is released from the AGB star with a velocity sufficient to escape the primary but not the binary. Such a situation could emanate from a thermal pulse, be induced by a periastron passage of the secondary, or could be launched if the primary ingests a planet.

  4. The impact of language co-activation on L1 and L2 speech fluency.

    Science.gov (United States)

    Bergmann, Christopher; Sprenger, Simone A; Schmid, Monika S

    2015-10-01

    Fluent speech depends on the availability of well-established linguistic knowledge and routines for speech planning and articulation. A lack of speech fluency in late second-language (L2) learners may point to a deficiency of these representations, due to incomplete acquisition. Experiments on bilingual language processing have shown, however, that there are strong reasons to believe that multilingual speakers experience co-activation of the languages they speak. We have studied to what degree language co-activation affects fluency in the speech of bilinguals, comparing a monolingual German control group with two bilingual groups: 1) first-language (L1) attriters, who have fully acquired German before emigrating to an L2 English environment, and 2) immersed L2 learners of German (L1: English). We have analysed the temporal fluency and the incidence of disfluency markers (pauses, repetitions and self-corrections) in spontaneous film retellings. Our findings show that learners to speak more slowly than controls and attriters. Also, on each count, the speech of at least one of the bilingual groups contains more disfluency markers than the retellings of the control group. Generally speaking, both bilingual groups-learners and attriters-are equally (dis)fluent and significantly more disfluent than the monolingual speakers. Given that the L1 attriters are unaffected by incomplete acquisition, we interpret these findings as evidence for language competition during speech production.

  5. Memória de trabalho e desempenho em tarefas de L2

    Directory of Open Access Journals (Sweden)

    Ingrid Fontanini

    2005-01-01

    Full Text Available O presente artigo examina se a natureza da relação entre memória de trabalho e desempenho em tarefas de língua estrangeira (L2 é geral ou específica. Uma bateria de quatro testes de memória de trabalho em inglês e quatro tarefas de desempenho foi aplicada em doze estudantes universitários de nível elementar em inglês como L2. A análise mostrou uma correlação significativa entre a medida geral de memória de trabalho e as tarefas de leitura, sintaxe e produção oral. Quanto às tarefas de memória de trabalho específicas, a medida de amplitude de leitura correlacionou significativamente com a tarefa de sintaxe, e a medida de amplitude oral correlacionou tanto com as tarefas de produção oral, quanto com as de sintaxe. Os resultados do presente estudo sinalizam para uma natureza híbrida da relação entre memória de trabalho e desempenho em tarefas em L2.This paper examines whether the nature of the relationship between working memory and the performance in L2 tasks is domain-free or task-specific. A set of four working memory tests in English and four L2 performance tasks was applied to twelve undergraduate beginner students of English as a second language. Correlational analyses showed significant correlation between the operation-word span test and the reading, syntactic and speaking tasks. As for the specific span tests, the reading span test correlated significantly with the syntactic task, and the speaking span test correlated both with the speech production task and the syntactic task. The results of the present study point to a hybrid nature of the relationship between working memory capacity and L2 task performance.

  6. 定点在日-地(月)系L1点附近的探测器的发射及维持%On the Transfer and Control of Spacecrafts Around the L1 Point of the Sun-Earth+Moon System

    Institute of Scientific and Technical Information of China (English)

    侯锡云; 刘林

    2007-01-01

    在限制性三体问题中共线平动点附近的运动虽然是不稳定的,但可以是有条件稳定的,该动力学特征使得一些有特殊目的的探测器只需消耗较少的能量即可定点在这些点附近(如ISEE-3、SOHO).以日-地(月)系的L1点为例,根据其附近的运动特征,探讨定点探测器的发射与轨道控制问题,给出了相应的数值模拟结果,为工程上的实现提供理论依据.

  7. English L2 reading getting to the bottom

    CERN Document Server

    Birch, Barbara M

    2014-01-01

    English L2 Reading, Third Edition offers teachers research-based insights into bottom-up skills in reading English as a second language and a solid foundation on which to build reading instruction. Core linguistic and psycholinguistic concepts are presented within the context of their application to teaching. The goal is to balance or supplement (not replace) top-down approaches and methodologies with effective low-level options for teaching English reading. The text's pedagogical features- Questions, Study Guide Questions. Discussion Questions, Spotlight on Teaching sections- engage readers o

  8. Effect of L2 phonetic learning on L1 vowels

    OpenAIRE

    Jiang, Haisheng

    2008-01-01

    This research examines the effect of L2 phonetic learning on L1 vowel production. Mandarin-English bilinguals differing in amount of L1 use produced Mandarin and English vowels. An acoustic analysis showed that both the Mandarin-English bilinguals of high L1 use and those of low L1 use deviated from the norm of Mandarin vowel /i/. The Mandarin-English bilinguals of low L1 use who successfully acquired English vowel /aj/ deviated from the norm of Mandarin vowel /aj/, indicating a carry-over ef...

  9. Strong limit theorems in noncommutative L2-spaces

    CERN Document Server

    Jajte, Ryszard

    1991-01-01

    The noncommutative versions of fundamental classical results on the almost sure convergence in L2-spaces are discussed: individual ergodic theorems, strong laws of large numbers, theorems on convergence of orthogonal series, of martingales of powers of contractions etc. The proofs introduce new techniques in von Neumann algebras. The reader is assumed to master the fundamentals of functional analysis and probability. The book is written mainly for mathematicians and physicists familiar with probability theory and interested in applications of operator algebras to quantum statistical mechanics.

  10. SYNCHRONOUS CMC, WORKING MEMORY, AND L2 ORAL PROFICIENCY DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    J. Scott Payne

    2005-09-01

    Full Text Available Recently a number of quasi-experimental studies have investigated the potential of a cross-modality transfer of second language competency between real-time, conversational exchange via text and speech (Abrams, 2003; Beauvious, 1998; Kost, 2004; Payne & Whitney, 2002. Payne and Whitney employed Levelt's (1989 model of language production and concepts from working memory as a rationale for a hypothesized connection between synchronous computer-mediated communication (SCMC and second language (L2 speech and as a basis for predicting the differential contributions of SCMC to the L2 oral proficiency development.This study extends the psycholinguistic framework reported in Payne and Whitney (2002 with discourse and corpus analytic techniques to explore how individual differences in working memory capacity may affect the frequency of repetition and other patterns of language use in chatroom discourse. Working memory capacity was measured by a reading span and nonword repetition test. Oral proficiency was measured with a speaking task that solicited a 5-minute speech sample and was scored based on a holistic scale. The data collected from 20 chat sessions were analyzed for occurrences of repetition and relexicalization, as well as language output measures. Findings suggest a connection between working memory and language output as measured in this study.

  11. Acquisition of L2 Japanese Geminates: Training with Waveform Displays

    Directory of Open Access Journals (Sweden)

    Miki Motohashi-Saigo

    2009-06-01

    Full Text Available The value of waveform displays as visual feedback was explored in a training study involving perception and production of L2 Japanese by beginning-level L1 English learners. A pretest-posttest design compared auditory-visual (AV and auditory-only (A-only Web-based training. Stimuli were singleton and geminate /t,k,s/ followed by /a,u/ in two conditions (isolated words, carrier sentences. Fillers with long vowels were included. Participants completed a forced-choice identification task involving minimal triplets: singletons, geminates, long vowels (e.g., sasu, sassu, saasu. Results revealed a significant improvement in geminate identification following training, especially for AV; b significant effect of geminate (lowest scores for /s/; c no significant effect of condition; and d no significant improvement for the control group. Most errors were misperceptions of geminates as long vowels. Test of generalization revealed 5% decline in accuracy for AV and 14% for A-only. Geminate production improved significantly (especially for AV based on rater judgments; improvement was greatest for /k/ and smallest for /s/. Most production errors involved substitution of a singleton for a geminate. Post-study interviews produced positive comments on Web-based training. Waveforms increased awareness of durational differences. Results support the effectiveness of auditory-visual input in L2 perception training with transfer to novel stimuli and improved production.

  12. Smart Grid Enabled L2 EVSE for the Commercial Market

    Energy Technology Data Exchange (ETDEWEB)

    Weeks, John [Eaton Corporation, Arden, NC (United States); Pugh, Jerry [Eaton Corporation, Arden, NC (United States)

    2015-03-31

    In 2011, the DOE issued Funding Opportunity DE-FOA-0000554 as a means of addressing two major task areas identified by the Grid Integration Tech Team (GITT) that would help transition Electric vehicles from a market driven by early adopters and environmental supporters to a market with mainstream volumes. Per DE-FOA-0000554, these tasks were: To reduce the cost of Electric Vehicle Supply Equipment (EVSE), thereby increasing the likelihood of the build out of EV charging infrastructure. The goal of increasing the number of EVSE available was to ease concerns over range anxiety, and promote the adoption of electric vehicles: To allow EV loads to be managed via the smart grid, thereby maintaining power quality, reliability and affordability, while protecting installed distribution equipment. In December of that year, the DOE awarded one of the two contracts targeted toward commercial EVSE to Eaton, and in early 2012, we began in earnest the process of developing a Smart Grid Enable L2 EVSE for the Commercial Market (hereafter known as the DOE Charger). The design of the Smart Grid Enabled L2 EVSE was based primarily on the FOA requirements along with input from the Electric Transportation Infrastructure product line (hereafter ETI) marketing team who aided in development of the customer requirements.

  13. L2 Orthogonal Space Time Code for Continuous Phase Modulation

    CERN Document Server

    Hesse, Matthias; Deneire, Luc

    2008-01-01

    To combine the high power efficiency of Continuous Phase Modulation (CPM) with either high spectral efficiency or enhanced performance in low Signal to Noise conditions, some authors have proposed to introduce CPM in a MIMO frame, by using Space Time Codes (STC). In this paper, we address the code design problem of Space Time Block Codes combined with CPM and introduce a new design criterion based on L2 orthogonality. This L2 orthogonality condition, with the help of simplifying assumption, leads, in the 2x2 case, to a new family of codes. These codes generalize the Wang and Xia code, which was based on pointwise orthogonality. Simulations indicate that the new codes achieve full diversity and a slightly better coding gain. Moreover, one of the codes can be interpreted as two antennas fed by two conventional CPMs using the same data but with different alphabet sets. Inspection of these alphabet sets lead also to a simple explanation of the (small) spectrum broadening of Space Time Coded CPM.

  14. On the Construction of Low-Energy Cislunar and Trans-lunar Transfers Based on the Libration Points

    CERN Document Server

    Xu, Ming; Xu, Shijie

    2014-01-01

    There exist cislunar and trans-lunar libration points near the Moon, which are referred as the LL1 and LL2 points respectively and can generate the different types of low-energy trajectories transferring from Earth to Moon. The time-dependent analytic model including the gravitational forces from the Sun, Earth and Moon is employed to investigate the energy-minimal and practical transfer trajectories. However, different from the circular restricted three-body problem, the equivalent gravitational equilibria are defined according to the geometry of instantaneous Hill's boundary due to the gravitational perturbation from the Sun. The relationship between the altitudes of periapsis and eccentricities is achieved from the Poincar\\'e mapping for all the lunar captured trajectories, which presents the statistical feature of the fuel cost and captured orbital elements rather than generating a specified Moon-captured segment. The minimum energy required by the captured trajectory on a lunar circular orbit is deduced ...

  15. Real Time Implementation of NARMA-L2 Control of a Single Link Manipulator

    Directory of Open Access Journals (Sweden)

    S. S. Mokri

    2008-01-01

    Full Text Available Nonlinearities and parametric uncertainties are unavoidable problems faced in controlling robot manipulator. A single link manipulator driven by a permanent magnet brushed dc motor is a nonlinear dynamics due to effects of gravitational force, mass of the payload, posture of the manipulator and viscous friction coefficient. Furthermore, uncertainties arise because of changes of the rotor resistance with temperature and random variation of friction while operating. Due to this fact, classical PID controller can not be used effectively since it is developed based on linear system theory. In order to overcome this problem, in this research, a neural network control scheme, NARMA-L2 Control is adopted and implemented in real time for controlling a DC motor driven single link manipulator with unknown dynamics. However, the real time experimentation showed that the proposed system results in chattering of the control signal. Hence, the system also chatters within the desired trajectory. As a solution, real time Smoothed NARMA-L2 Control scheme is implemented. Physical results showed that the improved control scheme has not only reduced the chattering but has successfully controlled the single link manipulator for both point-to-point and continuous path motion control.

  16. Double-Talk Detection Algorithm Based on the l2 Norm

    Institute of Scientific and Technical Information of China (English)

    Wang Shao-wei; Zhu Qiu-ping; Yang Yong

    2004-01-01

    Echo canceller generally needs a double-talk detector which is used to keep the adaptive filter from diverging in the appearance of near-end speech. In this paper we adopt a new double-talk detection algorithm based on l2 norm to detect the existence of near-end speech in an acoustic echo canceller. We analyze this algorithm from the point of view of functional analysis and point out that the proposed double-talk detection algorithm has the same performance as the classic one in a finite Banach space. The remarkable feature of this algorithm is its higher accuracy and better computation complexity. The fine properties of this algorithm are confirmed by computer simulation and the application in a multimedia communication system.

  17. The Influence of Positive Attitudes and Motivation on Successful L2 learning

    Institute of Scientific and Technical Information of China (English)

    陈影

    2015-01-01

    As the development of the second language learning(L2),it becomes more significant to study the factors that influence the success in L2 learning.Positive attitudes and motivation definitely play vital role in L2 learning process. This paper briefly analyses how these two factors influence L2 learning.

  18. The Influence of Positive Attitudes and Motivation on Successful L2 learning

    Institute of Scientific and Technical Information of China (English)

    陈影

    2015-01-01

    As the development of the second language learning(L2),it becomes more significant to study the factors that influence the success in L2 learning.Positive attitudes and motivation definitely play vital role in L2 learning process.This paper briefly analyses how these two factors influence L2learning.

  19. Profiles of More and Less Successful L2 Learners: A Cluster Analysis Study

    Science.gov (United States)

    Sparks, Richard L.; Patton, Jon; Ganschow, Leonore

    2012-01-01

    This retrospective study examined L1 achievement, intelligence, L2 aptitude, and L2 proficiency profiles of 208 students completing two years of high school L2 courses. A cluster analysis was performed to determine whether distinct cognitive and achievement profiles of more and less successful L2 learners would emerge. The results of…

  20. Initiating round robins in the L2 classroom - preliminary observations

    DEFF Research Database (Denmark)

    Mortensen, Kristian; Hazel, Spencer

    2011-01-01

    position in which round robins are initiated and how this is talked and embodied into being by the participants as well as the design of the turn that initiates the round robin activity. Relevant to the initiation and further development of the round robin are the physical arrangement of the classroom......Complementing recent interactional research on the contingent operation of online task accomplishment, this paper deals with a specific way of organizing and managing tasks in plenary L2 classrooms – namely the round robin. This may seem like a “traditional” and rigid form of classroom organization...... that reduces students’ contributions to responses to the teacher’s elicitations. This paper shows that although the round robin puts certain interactional features out of play, it is nonetheless done in and through participants’ mutual orientation to the ongoing activity. The paper describes the sequential...

  1. New Physics in {Delta}L = 2 neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Delepine, David; Gonzalez Macias, Vannia [Division de Ciencias e Ingenierias de la Universidad de Guanajuato, C.P. 37150, Leon, Guanajuato (Mexico); Khalil, Shaaban [Centre for Theoretical Physics, British University in Egypt, El Sherouk City, Postal No, 11837, PO Box 43 (Egypt); Lopez Castro, Gabriel [Departamento de Fisica, Cinvestav, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)

    2011-04-01

    We propose a general framework to constrain {Delta}L = 2 processes by measuring observables associated with neutrino-antineutrino oscillations in {pi}{sup {+-}} decays. First, we use this formalism as a new strategy for detecting the CP-violating phases and the effective mass of muon Majorana neutrinos. Within the generic framework of quantum field theory, we compute the non-factorizable probability for producing a pair of same-charged muons in {pi}{sup {+-}} decays as a distinctive signature of {nu}{sub {mu}}-{nu}*{sub {mu}}. Using the neutrino-antineutrino oscillation probability reported by MINOS collaboration, a new stringent bound on the effective muon-neutrino mass is derived. Secondly, we interpret the production of the pair of same-charged muons as a result of lepton number violating (LNV) interactions at the neutrino source, which allow us to constrain New Physics.

  2. Global magnetohydrodynamic instabilities in the L-2M stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Mikhailov, M. I., E-mail: mikhaylov-mi@nrcki.ru [National Research Centre Kurchatov Institute (Russian Federation); Shchepetov, S. V., E-mail: shch@fpl.gpi.ru [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Nührenberg, C.; Nührenberg, J. [Max-Planck-Institut für Plasmaphysik (Germany)

    2015-12-15

    Analysis of global magnetohydrodynamic (MHD) instabilities in the L-2M stellarator (Prokhorov General Physics Institute, Russian Academy of Sciences) is presented. The properties of free-boundary equilibria states are outlined, the stability conditions for small-scale modes are briefly discussed, and the number of trapped particles is estimated. All the magnetic configurations under study are stable against ballooning modes. It is shown that global ideal internal MHD modes can be found reliably only in Mercier unstable plasmas. In plasma that is stable with respect to the Mercier criterion, global unstable modes that are localized in the vicinity of the free plasma boundary and are not associated with any rational magnetic surface inside the plasma (the so-called peeling modes) can be found. The radial structure of all perturbations under study is almost entirely determined by the poloidal coupling of harmonics. The results of calculations are compared with the available experimental data.

  3. Overt and covert contrast in L2 phonology

    Science.gov (United States)

    Eckman, Fred R.; Iverson, Gregory K.; Song, Jae Yung

    2016-01-01

    This paper reports results on the acquisition of the English /p/ - /b/ contrast by native speakers of Arabic. This contrast does not exist in the participants’ native language (NL). The central finding of this study is that some of the research participants exhibited a covert contrast between these segments in their interlanguage productions. That is, two of the five Arabic-speaking participants who were transcribed as having no contrast between [p] and [b] did, in fact, produced a statistically reliable distinction in voice onset time lags between the two target segments. The existence of such an intermediate stage of covert contrast in the learning of L2 phonology is eminently plausible, in view of the progressive nature of phonological acquisition. Our results help bring the learning of second-language contrasts into conformity with findings of the same phenomenon in the areas of L1 acquisition and phonologically disordered speech. PMID:28090439

  4. Overt and covert contrast in L2 phonology.

    Science.gov (United States)

    Eckman, Fred R; Iverson, Gregory K; Song, Jae Yung

    2015-01-01

    This paper reports results on the acquisition of the English /p/ - /b/ contrast by native speakers of Arabic. This contrast does not exist in the participants' native language (NL). The central finding of this study is that some of the research participants exhibited a covert contrast between these segments in their interlanguage productions. That is, two of the five Arabic-speaking participants who were transcribed as having no contrast between [p] and [b] did, in fact, produced a statistically reliable distinction in voice onset time lags between the two target segments. The existence of such an intermediate stage of covert contrast in the learning of L2 phonology is eminently plausible, in view of the progressive nature of phonological acquisition. Our results help bring the learning of second-language contrasts into conformity with findings of the same phenomenon in the areas of L1 acquisition and phonologically disordered speech.

  5. Control of asteroid retrieval trajectories to libration point orbits

    Science.gov (United States)

    Ceriotti, Matteo; Sanchez, Joan Pau

    2016-09-01

    The fascinating idea of shepherding asteroids for science and resource utilization is being considered as a credible concept in a not too distant future. Past studies identified asteroids which could be efficiently injected into manifolds which wind onto periodic orbits around collinear Lagrangian points of the Sun-Earth system. However, the trajectories are unstable, and errors in the capture maneuver would lead to complete mission failure, with potential danger of collision with the Earth, if uncontrolled. This paper investigates the controllability of some asteroids along the transfers and the periodic orbits, assuming the use of a solar-electric low-thrust system shepherding the asteroid. Firstly, an analytical approach is introduced to estimate the stability of the trajectories from a dynamical point of view; then, a numerical control scheme based on a linear quadratic regulator is proposed, where the gains are optimized for each trajectory through a genetic algorithm. A stochastic simulation with a Monte Carlo approach is used to account for different perturbed initial conditions and the epistemic uncertainty on the asteroid mass. Results show that only a small subset of the considered combinations of trajectories/asteroids are reliably controllable, and therefore controllability must be taken into account in the selection of potential targets.

  6. Stochastic analysis of the control of the movement of the spacecraft in the vicinity of the colinear libration point by means of the forces of luminous pressure

    Science.gov (United States)

    Lukyanov, S. S.

    1983-01-01

    This paper is dedicated to the possible investigation of the utilization of the solar radiation pressure for the spacecraft motion control in the vicinity of collinear libration point of planar restricted ring problem of three bodies. The control is realized by changing the solar sail area at its permanent orientation. In this problem the influence of the trajectory errors and the errors of the execution control is accounted. It is worked out, the estimation method of the solar sail sizes, which are necessary for spacecraft keeping in the vicinity of collinear libration point during the certain time with given probability. The main control parameters were calculated for some examples in case of libration points of the Sun-Earth and Earth-Moon systems.

  7. IMPARARE L’ITALIANO L2/LS CON TESTI TEATRALI

    Directory of Open Access Journals (Sweden)

    Erminia Ardissino

    2010-09-01

    Full Text Available Il saggio tratta dell'impiego di testi teatrali come fonti di esercizi per l'apprendimento dell'italiano L2/LS. Dopo alcune riflessioni teoriche, si presentano sei proposte di lavoro, con relative soluzioni, adatte a studenti del livello B2-C2 del quadro di riferimento. Si tratta di esercizi ricavati da drammi in un unico atto di Pirandello (La morsa e Lumìe di Sicilia, da Verga (un confronto fra Cavalleria rusticana nella forma drammatica e novellistica, e da Tommaso Landolfi (Ombre. Ogni proposta sfrutta una peculiarità del testo teatrale che si costituisce nell'incontro di dialoghi con didascalie. Anzitutto si tratta di comprendere come si costruiscono i personaggi, quindi di vedere la funzione delle didascalie in relazione al testo, infine di riflettere sulle diverse modalità in cui avvengono i dialoghi, includendo le forme di silenzio. Il testo teatrale appare così molto adatto ad esercizi di lingua, perché mette in gioco le capacità interpretative e immaginative degli studenti, li fa discutere e parlare sulla base delle loro intuizioni.   This paper investigates the use of play scripts as inspiration for Italian L2/FL exercises. After a brief discussion on theory, six project proposals and their solutions, suitable for B2-C2 level students, are presented.  These exercises are based on one-act plays by Pirandello (La Morsa and Lumìe di Sicilia, Verga (a comparison between Cavalleria Rusticana in drama and narrative forms and Tommaso Landolfi (Ombre.  Each project focuses on a specific aspect of the script  and is made up of dialogues with captions. After the way the characters are constructed is investigated, then the function of the captions in relation to the texts is considered, and finally students reflect on the different ways the dialogues are presented, including the pauses. Play scripts lend themselves to language exercises, because they encourage students to use their interpretation skills and imaginations to talk about

  8. L2 willingness to communicate (WTC and international posture in the Polish educational context

    Directory of Open Access Journals (Sweden)

    Anna Mystkowska-Wiertelak

    2011-08-01

    Full Text Available Speaking, the language skill whose mastering appears to be the ultimate aim of every attempt at learning a foreign language, constitutes a formidable challenge. Apart from involving the online interaction of complex processes of conceptualization, formulation, articulation and monitoring (Levelt, 1989, it appears prone to numerous psychological and social influences that, being difficult to control, may consistently hinder development. One of such factors, closely related to the concept of anxiety, is L2 willingness to communicate (WTC, called “the most immediate determinant of L2 use” (Clement, Baker, & MacIntyre, 2003, p. 191. Perceived as either a personality trait or/and a context-related feature, WTC seems capable of accounting for a person’s first and second language communication. Interestingly it can be related to the learner’s disposition towards the target language culture, general interest in international affairs, willingness to travel and sustain contacts with speakers of other languages, which, defined as international posture (Yashima, 2002, serves as a strong predictor of success in language learning. The present paper reports the results of a survey conducted among 111 students of English, in the majority prospect teachers of English. The aim was to establish the degree of correlation between their international posture and WTC. The results do not corroborate the outcomes of other studies performed in the field (cf. Yashima, 2002, 2009, which might point to the unique characteristics of the Polish educational context.

  9. James Webb Space Telescope - L2 Communications for Science Data Processing

    Science.gov (United States)

    Johns, Alan; Seaton, Bonita; Gal-Edd, Jonathan; Jones, Ronald; Fatig, Curtis; Wasiak, Francis

    2008-01-01

    JWST is the first NASA mission at the second Lagrange point (L2) to identify the need for data rates higher than 10 megabits per second (Mbps). JWST will produce approximately 235 Gigabits of science data every day that will be downlinked to the Deep Space Network (DSN). To get the data rates desired required moving away from X-band frequencies to Ka-band frequencies. To accomplish this transition, the DSN is upgrading its infrastructure. This new range of frequencies are becoming the new standard for high data rate science missions at L2. With the new frequency range, the issues of alternatives antenna deployment, off nominal scenarios, NASA implementation of the Ka-band 26 GHz, and navigation requirements will be discussed in this paper. JWST is also using Consultative Committee for Space Data Systems (CCSDS) standard process for reliable file transfer using CCSDS File Delivery Protocol (CFDP). For JWST the use of the CFDP protocol provides level zero processing at the DSN site. This paper will address NASA implementations of Ground Stations in support of Ka-band 26 GHz and lesson learned from implementing a file base (CFDP) protocol operational system.

  10. L2 Spelling Errors in Italian Children with Dyslexia.

    Science.gov (United States)

    Palladino, Paola; Cismondo, Dhebora; Ferrari, Marcella; Ballagamba, Isabella; Cornoldi, Cesare

    2016-05-01

    The present study aimed to investigate L2 spelling skills in Italian children by administering an English word dictation task to 13 children with dyslexia (CD), 13 control children (comparable in age, gender, schooling and IQ) and a group of 10 children with an English learning difficulty, but no L1 learning disorder. Patterns of difficulties were examined for accuracy and type of errors, in spelling dictated short and long words (i.e. disyllables and three syllables). Notably, CD were poor in spelling English words. Furthermore, their errors were mainly related with phonological representation of words, as they made more 'phonologically' implausible errors than controls. In addition, CD errors were more frequent for short than long words. Conversely, the three groups did not differ in the number of plausible ('non-phonological') errors, that is, words that were incorrectly written, but whose reading could correspond to the dictated word via either Italian or English rules. Error analysis also showed syllable position differences in the spelling patterns of CD, children with and English learning difficulty and control children. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Blogging Identity: How L2 Learners Express Themselves

    Directory of Open Access Journals (Sweden)

    Kiyomi FUJII

    2015-06-01

    Full Text Available This study discusses language learning and identity, particularly pertaining to intermediate-advanced-level Japanese-language learners, focusing on their target language and identity expression through their interactions with peers and Japanese college students. When learners of Japanese express their identities while interacting with others in their target language, they feel a gap between the self-image they want to present, and the image they are capable of presenting in Japanese (Siegal, 1994, 1995, 1996. Along with adjusting their L1 and L2 usage depending on their interlocutor (Kurata 2007, learners also use different sentence-ending styles depending on the role they want to assume (Cook 2008. By conducting a case study, the present inquiry attempts to address how learners of Japanese express their identities through blog conversations, focusing on their language choice and expressions. Results suggest that participants use the formal endings for self-presentation and projection of their student and classmate identity. However, when expressing emotion some students preferred informal endings, or sentence-final particles.

  12. Dyadic Bivariate Wavelet Multipliers in L2(R2)

    Institute of Scientific and Technical Information of China (English)

    Zhong Yan LI; Xian Liang SHI

    2011-01-01

    The single 2 dilation wavelet multipliers in one-dimensional case and single A-dilation (where A is any expansive matrix with integer entries and |detA|=2)wavelet multipliers in twodimensional case were completely characterized by Wutam Consortium(1998)and Li Z.,et al.(2010).But there exist no results on multivariate wavelet multipliers corresponding to integer expansive dilation.matrix with the absolute value of determinant not 2 in L2(R2).In this paper,we choose 2I2=(0202)as the dilation matrix and consider the 2I2-dilation multivariate wavelet Ψ={ψ1,ψ2,ψ3}(which is called a dyadic bivariate wavelet)multipliers.Here we call a measurable function family f={f1,f2,f3}a dyadic bivariate wavelet multiplier if Ψ1={F-1(f1ψ1),F-1(f2ψ2),F-1(f3ψ3)} is a dyadic bivariate wavelet for any dyadic bivariate wavelet Ψ={ψ1,ψ2,ψ3},where(f)and,F-1 denote the Fourier transform and the inverse transform of function f respectively.We study dyadic bivariate wavelet multipliers,and give some conditions for dyadic bivariate wavelet multipliers.We also give concrete forms of linear phases of dyadic MRA bivariate wavelets.

  13. Wavelet Decomposition Method for $L_2/$/TV-Image Deblurring

    KAUST Repository

    Fornasier, M.

    2012-07-17

    In this paper, we show additional properties of the limit of a sequence produced by the subspace correction algorithm proposed by Fornasier and Schönlieb [SIAM J. Numer. Anal., 47 (2009), pp. 3397-3428 for L 2/TV-minimization problems. An important but missing property of such a limiting sequence in that paper is the convergence to a minimizer of the original minimization problem, which was obtained in [M. Fornasier, A. Langer, and C.-B. Schönlieb, Numer. Math., 116 (2010), pp. 645-685 with an additional condition of overlapping subdomains. We can now determine when the limit is indeed a minimizer of the original problem. Inspired by the work of Vonesch and Unser [IEEE Trans. Image Process., 18 (2009), pp. 509-523], we adapt and specify this algorithm to the case of an orthogonal wavelet space decomposition for deblurring problems and provide an equivalence condition to the convergence of such a limiting sequence to a minimizer. We also provide a counterexample of a limiting sequence by the algorithm that does not converge to a minimizer, which shows the necessity of our analysis of the minimizing algorithm. © 2012 Society for Industrial and Applied Mathematics.

  14. Analysis of glycosidases activity in Chlamydia trachomatis L2 serotype

    Directory of Open Access Journals (Sweden)

    Dr. Sanjiv Rughooputh

    2006-01-01

    Full Text Available Chlamydiae are prokaryotic, gram negative, intracellular parasites, causing a number of human diseases with serious sequelae. The exact mechanism of chlamydial attachment and entry into the host cell is still unclear. Chlamydia trachomatis, SA2F (L2 was tested for the activity of glycosidases. Glycosidases are involved in the synthesis and breakdown of cell-wall polysaccharides, and have a pivotal role in attachment to the surface of host cells as well as in the invasion process of other infective agents. For these reasons, glycosidases are likely to provide important information regarding the general behaviour of this bacterium. Ten different glycosides bound to p-nitrophenol (pNP substrate were tested. Assays were performed on lysed and unlysed chlamydial extracts.Our results provided strong evidence for the existence of glycosidase activity in C.trachomatis, strain SA2F peaking at pH 5.0 and pH 7.5-8.0 There was a high enzymatic activity against p-NPa mannopyranoside and p-NP b-N acetylglucosamine with a recovery of 88% suggesting that the enzymes were present on the bacterial surface. Activity against these sugars, which form part of either the extracellular filler or in endoplasmic reticulum may suggest of a possible mechanism of cellular invasion.

  15. The perceptual magnet effect (PME) in L2 consonants

    Science.gov (United States)

    Hattori, Kota

    2005-09-01

    The perceptual magnet effect (PME) has been investigated in conjunction with L1 vowels and consonants. However, there has been a paucity of examinations of the effect in L2 speech perception. The present study used the methodology of Iverson and Kuhl [P. Iverson and P. K. Kuhl, J. Acoust. Soc. Am. 99, 1130-1140 (1996)] to examine whether Japanese speakers who have had exposure to English-speaking environments for more than 1 year exhibit the PME for /r/ and /l/. Eighteen synthetic stimuli were generated. Ten Japanese speakers and 12 American English speakers participated in an identification and rating task. Each participant engaged in ten experimental sessions (ten sessions of each of the 18 stimuli). They chose either /ra/ or /la/ and gave a rating with a 1-7 scale. They also underwent a similarity scaling task to determine the similarity of 306 pairs of the 18 stimuli with a 1-7 scale. The results indicated that, while the English speakers demonstrated the PME, some native speakers of Japanese did exhibit the PME and prefer some exemplars of English /r/ and /l/ over others. The results also revealed that other Japanese speakers exhibited reorganized perceptual space without the PME.

  16. L2 Learners’ Proficiency Development through Noticing Feedback

    Directory of Open Access Journals (Sweden)

    Seyed Saber Alavi

    2015-10-01

    Full Text Available This experimental study investigated the relationship between noticing of corrective feedback and L2 development considering the learners’ perspective on error correction. Specifically, it aimed to uncover the noticeability and effectiveness of recasts, prompts, a combination of the two, to determine a relationship between noticing of CF and learning of the past tense. The participants were four groups of college ESL learners (n = 40. Each group was assigned to a treatment condition, but the researcher taught the control group. CF was provided to learners in response to their mistakes in forming the past tense. While noticing of CF was assessed through immediate recall and questionnaire responses, learning outcomes were measured through picture description administered via pre-test, post-test, and delayed post-test design. Learner beliefs about CF were probed by means of a 40-item questionnaire. The results indicated that the noticeability of CF is dependent on the grammatical target it addresses and that the feedback techniques that push learners to self-correct alone or in combination with target exemplars are more effective in. In relation to the learning outcomes, the overall past tense accuracy increased more than that for questions, but there were no significant differences between the groups. Finally, in relation to the beliefs about CF, the participants’ responses centered on the importance of oral CF, recasts as CF technique, prompts as CF technique, and affective consequences of CF, two of which mediated the noticeability of the supplied CF, but none impacted the learning outcomes.

  17. New Developments in the SCIAMACHY L2 Ground Processor

    Science.gov (United States)

    Gretschany, Sergei; Lichtenberg, Günter; Meringer, Markus; Theys, Nicolas; Lerot, Christophe; Liebing, Patricia; Noel, Stefan; Dehn, Angelika; Fehr, Thorsten

    2016-04-01

    SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric ChartographY) aboard ESA's environmental satellite ENVISAT observed the Earth's atmosphere in limb, nadir, and solar/lunar occultation geometries covering the UV-Visible to NIR spectral range. It is a joint project of Germany, the Netherlands and Belgium and was launched in February 2002. SCIAMACHY doubled its originally planned in-orbit lifetime of five years before the communication to ENVISAT was severed in April 2012, and the mission entered its post-operational phase. In order to preserve the best quality of the outstanding data recorded by SCIAMACHY, data processors are still being updated. This presentation will highlight three new developments that are currently being incorporated into the forthcoming Version 7 of ESA's operational Level 2 processor: 1. Tropospheric BrO, a new retrieval based on the scientific algorithm of (Theys et al., 2011). This algorithm had been originally developed for the GOME-2 sensor and later adapted for SCIAMACHY. The main principle of the new algorithm is to utilize BrO total columns (already an operational product) and split them into stratospheric VCDstrat and tropospheric VCDtrop fractions. BrO VCDstrat is determined from a climatological approach, driven by SCIAMACHY O3 and NO2 observations. VCDtrop is then determined simply as a difference: VCDtrop = VCDtotal - VCDstrat. 2. Improved cloud flagging using limb measurements (Liebing, 2015). Limb cloud flags are already part of the SCIAMACHY L2 product. They are currently calculated employing the scientific algorithm developed by (Eichmann et al., 2015). Clouds are categorized into four types: water, ice, polar stratospheric and noctilucent clouds. High atmospheric aerosol loadings, however, often lead to spurious cloud flags, when aerosols had been misidentified as clouds. The new algorithm will better discriminate between aerosol and clouds. It will also have a higher sensitivity w.r.t. thin clouds. 3. A new

  18. L2 Classroom Interaction: A Sociocultural Theoretical Perspective

    OpenAIRE

    武田, 礼子

    2015-01-01

    本稿は,社会文化理論から見た外国語学習における教室内相互行為を考察する。まず,学習者の認知的発達が社会的かつ文化的に形成されると論じるヴィゴツキーの社会文化理論の4つの概念である媒介,最近接発達領域,足場掛け,ランゲージングについて論じる。次に社会文化理論からみた外国語学習における相互行為の先行研究を紹介する。ここでは上級者主導の相互行為,異なる母語の学習者間の相互行為,また一人の学習者における自己内省による相互行為を含む。それらの研究を通して学習者間の相互行為の潜在的可能性を考察し,学習の機会を最大限に生かすための提案をする。This article reviews studies on classroom interaction in the L2 classroom from a sociocultural theoretical perspective. These studies posit that a person’s cognitive development is socially and culturally created. The paper first ...

  19. Culturally Responsive L2 Education: An Awareness-Raising Proposal

    Science.gov (United States)

    Porto, Melina

    2010-01-01

    The increasing prevalence of multilingual, multiethnic, and multicultural classrooms in varied educational contexts worldwide points to the importance of cultural factors in language education and education in general. In the EFL/ESL classroom of this century, ELT is seen as including much more than purely linguistic aspects as it focuses also on…

  20. Do L2 Writing Courses Affect the Improvement of L1 Writing Skills via Skills Transfer from L2 to L1?

    Science.gov (United States)

    Gonca, Altmisdort

    2016-01-01

    This study investigates the relationship of second language (L2) writing skills proficiency with the first language (L1) writing skills, in light of the language transfer. The study aims to analyze the positive effects of L2 writing proficiency on L1 writing proficiency. Forty native Turkish-speaking university students participated in the study.…

  1. Bilingual lexical access during L1 sentence reading: The effects of L2 knowledge, semantic constraint, and L1-L2 intermixing.

    Science.gov (United States)

    Titone, Debra; Libben, Maya; Mercier, Julie; Whitford, Veronica; Pivneva, Irina

    2011-11-01

    Libben and Titone (2009) recently observed that cognate facilitation and interlingual homograph interference were attenuated by increased semantic constraint during bilingual second language (L2) reading, using eye movement measures. We now investigate whether cross-language activation also occurs during first language (L1) reading as a function of age of L2 acquisition and task demands (i.e., inclusion of L2 sentences). In Experiment 1, participants read high and low constraint English (L1) sentences containing interlingual homographs, cognates, or control words. In Experiment 2, we included French (L2) filler sentences to increase salience of the L2 during L1 reading. The results suggest that bilinguals reading in their L1 show nonselective activation to the extent that they acquired their L2 early in life. Similar to our previous work on L2 reading, high contextual constraint attenuated cross-language activation for cognates. The inclusion of French filler items promoted greater cross-language activation, especially for late stage reading measures. Thus, L1 bilingual reading is modulated by L2 knowledge, semantic constraint, and task demands.

  2. Phonological Memory and the Acquisition of Grammar in Child L2 Learners

    Science.gov (United States)

    Verhagen, Josje; Leseman, Paul; Messer, Marielle

    2015-01-01

    Previous studies show that second language (L2) learners with large phonological memory spans outperform learners with smaller memory spans on tests of L2 grammar. The current study investigated the relationship between phonological memory and L2 grammar in more detail than has been done earlier. Specifically, we asked how phonological memory…

  3. Investigating the Role of Multiple Intelligences in Determining Vocabulary Learning Strategies for L2 Learners

    Science.gov (United States)

    Sistani, Mahsa; Hashemian, Mahmood

    2016-01-01

    This study, first, examined whether there was any relationship between Iranian L2 learners' vocabulary learning strategies (VLSs), on the one hand, and their multiple intelligences (MI) types, on the other hand. In so doing, it explored the extent to which MI would predict L2 learners' VLSs. To these ends, 40 L2 learners from Isfahan University of…

  4. CALL--Enhanced L2 Listening Skills--Aiming for Automatization in a Multimedia Environment

    Science.gov (United States)

    Mayor, Maria Jesus Blasco

    2009-01-01

    Computer Assisted Language Learning (CALL) and L2 listening comprehension skill training are bound together for good. A neglected macroskill for decades, developing listening comprehension skill is now considered crucial for L2 acquisition. Thus this paper makes an attempt to offer latest information on processing theories and L2 listening…

  5. Repetition and Focus on Form in Processing L2 Spanish Words: Implications for Pronunciation Instruction

    Science.gov (United States)

    Trofimovich, Pavel; Gatbonton, Elizabeth

    2006-01-01

    Situated in the context of learning second language (L2) pronunciation, this article discusses from information-processing and pedagogical perspectives the role of repetitive practice with L2 input and of explicit focus on its form-related (phonological) properties. First, we report the results of an auditory word-priming experiment with 60 L2

  6. L^2-Betti numbers of rigid C*-tensor categories and discrete quantum groups (preprint)

    DEFF Research Database (Denmark)

    Kyed, David; Raum, Sven; Vaes, Stefaan;

    2017-01-01

    We compute the $L^2$-Betti numbers of the free $C^*$-tensor categories, which are the representation categories of the universal unitary quantum groups $A_u(F)$. We show that the $L^2$-Betti numbers of the dual of a compact quantum group $G$ are equal to the $L^2$-Betti numbers of the representat...

  7. Learning L2 German vocabulary through reading: the effect of three enhancement techniques compared

    NARCIS (Netherlands)

    Peters, E.; Hulstijn, J.H.; Sercu, L.; Lutjeharms, M.

    2009-01-01

    This study investigated three techniques designed to increase the chances that second language (L2) readers look up and learn unfamiliar words during and after reading an L2 text. Participants in the study, 137 college students in Belgium (L1 = Dutch, L2 = German), were randomly assigned to one of

  8. Effects of Glosses on Learning of L2 Grammar and Vocabulary

    Science.gov (United States)

    Jung, Jookyoung

    2016-01-01

    The present study examines how glossing of second language (L2) texts affects L2 learners' reading comprehension as well as their learning of L2 grammar and vocabulary. It employed a pretest, immediate posttest, and delayed posttest design with two treatment sessions. The target features were English unaccusativity and 10 pseudo-word items.…

  9. A Prerequisite to L1 Homophone Effects in L2 Spoken-Word Recognition

    Science.gov (United States)

    Nakai, Satsuki; Lindsay, Shane; Ota, Mitsuhiko

    2015-01-01

    When both members of a phonemic contrast in L2 (second language) are perceptually mapped to a single phoneme in one's L1 (first language), L2 words containing a member of that contrast can spuriously activate L2 words in spoken-word recognition. For example, upon hearing cattle, Dutch speakers of English are reported to experience activation…

  10. Perceptual Filtering in L2 Lexical Memory: A Neural Network Approach to Second Language Acquisition

    Science.gov (United States)

    Nelson, Robert

    2012-01-01

    A number of asymmetries in lexical memory emerge when monolinguals and early bilinguals are compared to (relatively) late second language (L2) learners. Their study promises to provide insight into the internal processes that both support and ultimately limit L2 learner achievement. Generally, theory building in L2 and bilingual lexical memory has…

  11. Investigating an Innovative Computer Application to Improve L2 Word Recognition from Speech

    Science.gov (United States)

    Matthews, Joshua; O'Toole, John Mitchell

    2015-01-01

    The ability to recognise words from the aural modality is a critical aspect of successful second language (L2) listening comprehension. However, little research has been reported on computer-mediated development of L2 word recognition from speech in L2 learning contexts. This report describes the development of an innovative computer application…

  12. SLA Research and L2 Pedagogy: Misapplications and Questions of Relevance

    Science.gov (United States)

    Spada, Nina

    2015-01-01

    There has been considerable debate about the relevance and applicability of SLA theory and research for L2 pedagogy. There are those who maintain that SLA must be applicable to L2 pedagogy: a view based on the argument that because SLA is a subfield of applied linguistics, it should have direct relevance to L2 teaching. Others take the view that…

  13. Factors Affecting Grammatical and Lexical Complexity of Long-Term L2 Speakers' Oral Proficiency

    Science.gov (United States)

    Lahmann, Cornelia; Steinkrauss, Rasmus; Schmid, Monika S.

    2016-01-01

    There remains considerable disagreement about which factors drive second language (L2) ultimate attainment. Age of onset (AO) appears to be a robust factor, lending support to theories of maturational constraints on L2 acquisition. The present study is an investigation of factors that influence grammatical and lexical complexity at the stage of L2

  14. Morphological and Syntactic Transfer in Child L2 Acquisition of the English Dative Alternation.

    Science.gov (United States)

    Whong-Barr, Melinda; Schwartz, Bonnie D.

    2002-01-01

    Compares the acquisition of the English to- and for-dative alternation by native-speaking English, Japanese, and Korean children. Investigates whether second language learners (L2) like native language learners overextend the double-object variant and whether L2 learners, like L2 adults, transfer properties of the native language grammar.…

  15. Semantic Categorization of Placement Verbs in L1 and L2 Danish and Spanish

    Science.gov (United States)

    Cadierno, Teresa; Ibarretxe-Antuñano, Iraide; Hijazo-Gascón, Alberto

    2016-01-01

    This study investigates semantic categorization of the meaning of placement verbs by Danish and Spanish native speakers and two groups of intermediate second language (L2) learners (Danish learners of L2 Spanish and Spanish learners of L2 Danish). Participants described 31 video clips picturing different types of placement events. Cluster analyses…

  16. Perceptual Filtering in L2 Lexical Memory: A Neural Network Approach to Second Language Acquisition

    Science.gov (United States)

    Nelson, Robert

    2012-01-01

    A number of asymmetries in lexical memory emerge when monolinguals and early bilinguals are compared to (relatively) late second language (L2) learners. Their study promises to provide insight into the internal processes that both support and ultimately limit L2 learner achievement. Generally, theory building in L2 and bilingual lexical memory has…

  17. SLA Research and L2 Pedagogy: Misapplications and Questions of Relevance

    Science.gov (United States)

    Spada, Nina

    2015-01-01

    There has been considerable debate about the relevance and applicability of SLA theory and research for L2 pedagogy. There are those who maintain that SLA must be applicable to L2 pedagogy: a view based on the argument that because SLA is a subfield of applied linguistics, it should have direct relevance to L2 teaching. Others take the view that…

  18. Individual Variation in L2 Study-Abroad Outcomes: A Case Study from Indonesian Pragmatics

    Science.gov (United States)

    Hassall, Timothy

    2015-01-01

    This is a study of two Australian learners of Indonesian during a short stay abroad. It examines their contrasting success in acquiring L2 address terms, in tandem with their contrasting experiences of the L2 culture setting. It thereby helps explain the persistent finding of great individual variation in L2 gains--and in particular pragmatic…

  19. Implicit prosody and cue-based retrieval: L1 and L2 agreement and comprehension during reading

    Directory of Open Access Journals (Sweden)

    Elizabeth Pratt

    2016-12-01

    Full Text Available This project focuses on structural and prosodic effects during reading, examining their influence on agreement processing and comprehension in native English (L1 and Spanish-English bilingual (L2 speakers. We consolidate research from several distinct areas of inquiry—cognitive processing, reading fluency, and L1/L2 processing—in order to support the integration of prosody with a cue-based retrieval mechanism for subject-verb agreement.To explore this proposal, the experimental design manipulated text presentation to influence implicit prosody, using sentences designed to induce subject-verb agreement attraction errors. Materials included simple and complex relative clauses with head nouns and verbs that were either matched or mismatched for number. Participants read items in one of three presentation formats (whole sentence, word-by-word, or phrase-by-phrase, rated each item for grammaticality, and responded to a comprehension probe. Results indicated that while overall, message comprehension was prioritized over subject-verb agreement computation, presentation format differentially affected both measures in the L1 and L2 groups. For the L1 participants, facilitating the projection of phrasal prosody onto text (phrase-by-phrase presentation enhanced performance in agreement processing, while disrupting prosodic projection via word-by-word presentation decreased comprehension accuracy. For the L2 participants however, phrase-by-phrase presentation was not significantly beneficial for agreement processing, and also resulted in lower comprehension accuracy. These differences point to a significant role of prosodic phrasing during agreement processing in both L1 and L2 speakers, additionally suggesting that it may contribute to a cue-based retrieval agreement model, either acting as a cue directly, or otherwise scaffolding the retrieval process. The discussion and results presented provide support both for a cue-based retrieval mechanism in

  20. Unbalanced Bilinguals’ Asymmetric Associations Between L2 Words for Taxonomic Categories of Basic and Superordinate Levels

    Directory of Open Access Journals (Sweden)

    Bohua Chen

    2016-03-01

    Full Text Available The revised hierarchical model seems different from the distributed conceptual feature model in predicting how unbalanced bilinguals would be aware of semantic relations between words for taxonomic categories of basic level (exemplar words and words for those of superordinate level (category names in L2. We did a series of four experiments to compare unbalanced bilinguals’ awareness of conceptual relations between exemplar words and between exemplar words and category names in their first (L1 and second language (L2. A priming task of semantic categorization was adopted, and the participants were 72 college students, who began to learn L2 in classroom settings at a late age and achieved an L2 proficiency between intermediate and advanced levels. The reaction times indicated that the participants could automatically process not only the exemplar-word but also the category-name primes in L2. Activations of semantic representations for the category names in L2 seemed to spread to those for the exemplar words in L1 and L2, but activations of semantic presentations for the exemplar words in L2 spread only to those for the example words in L1 for the participants. It was concluded that unbalanced bilinguals appear to have developed asymmetric associations between category names and exemplar words in L2. The implication is that L2 learners should learn L2 words mainly by means of using the language and not taking rote memory of isolated words.

  1. Do the Four Clades of the mtDNA Haplogroup L2 Evolve at Different Rates?

    Science.gov (United States)

    Torroni, Antonio; Rengo, Chiara; Guida, Valentina; Cruciani, Fulvio; Sellitto, Daniele; Coppa, Alfredo; Calderon, Fernando Luna; Simionati, Barbara; Valle, Giorgio; Richards, Martin; Macaulay, Vincent; Scozzari, Rosaria

    2001-01-01

    Forty-seven mtDNAs collected in the Dominican Republic and belonging to the African-specific haplogroup L2 were studied by high-resolution RFLP and control-region sequence analyses. Four sets of diagnostic markers that subdivide L2 into four clades (L2a–L2d) were identified, and a survey of published African data sets appears to indicate that these clades encompass all L2 mtDNAs and harbor very different geographic/ethnic distributions. One mtDNA from each of the four clades was completely sequenced by means of a new sequencing protocol that minimizes time and expense. The phylogeny of the L2 complete sequences showed that the two mtDNAs from L2b and L2d seem disproportionately derived, compared with those from L2a and L2c. This result is not consistent with a simple model of neutral evolution with a uniform molecular clock. The pattern of nonsynonymous versus synonymous substitutions hints at a role for selection in the evolution of human mtDNA. Regardless of whether selection is shaping the evolution of modern human mtDNAs, the population screening of L2 mtDNAs for the mutations identified by our complete sequence study should allow the identification of marker motifs of younger age with more restricted geographic distributions, thus providing new clues about African prehistory and the origin and relationships of African ethnic groups. PMID:11595973

  2. Diorgano,Dichloro-tin (IV) Complexes of 4-X-Benzohydroxamic Acid (X=Cl,OCH3):Synthesis,Characterization,Antitumor Activity in Vitro and the Crystal Structure of trans-[Me2Sn(L2)2

    Institute of Scientific and Technical Information of China (English)

    Jing Hua ZHAO; Tai Gang LIANG; Qing Shan LI; Armando J.L.Pombeiro

    2003-01-01

    A series of diorganotin (IV) derivatives of R2SnL2 (R = Me, Et, n-Bu, ph or Cl; L = L1 or L2) and their corresponding mixed-ligand complexes R2Sn (L1)(L2) have been prepared and the structure of trans-Me2Sn (L2) 2 was characterized by FT-IR, 1H, 13C and 119Sn NMR spectroscopies, MS, elemental analysis, melting points and X-ray diffraction. The structure-activity relationships were discussed.

  3. Analysis of Discrete L2 Projection on Polynomial Spaces with Random Evaluations

    KAUST Repository

    Migliorati, Giovanni

    2014-03-05

    We analyze the problem of approximating a multivariate function by discrete least-squares projection on a polynomial space starting from random, noise-free observations. An area of possible application of such technique is uncertainty quantification for computational models. We prove an optimal convergence estimate, up to a logarithmic factor, in the univariate case, when the observation points are sampled in a bounded domain from a probability density function bounded away from zero and bounded from above, provided the number of samples scales quadratically with the dimension of the polynomial space. Optimality is meant in the sense that the weighted L2 norm of the error committed by the random discrete projection is bounded with high probability from above by the best L∞ error achievable in the given polynomial space, up to logarithmic factors. Several numerical tests are presented in both the univariate and multivariate cases, confirming our theoretical estimates. The numerical tests also clarify how the convergence rate depends on the number of sampling points, on the polynomial degree, and on the smoothness of the target function. © 2014 SFoCM.

  4. Encapsidating artificial human papillomavirus-16 mE7 protein in human papillomavirus-6b L1/L2 virus like particles

    Institute of Scientific and Technical Information of China (English)

    XU Yu-fei; WANG Qing-yong; ZHANG Hong-tao; HAN Ye-hua; SONG Guo-xing; XU Xue-mei

    2007-01-01

    Background Human papillomaviruses (HPVs) can infect squamous or mucosal epithelia and cause cervical cancer or genital warts. Coinfection with multiple HPV types is a common finding of many epidemiological studies. Therefore, it is necessary to develop a vaccine, which can eradicate established HPV infections and prevent other HPV infections. In this study, we generated chimeric virus like particles (cVLPs) composed of HPV-6b L1, HPV-6b L2 and one artificial HPV-16 mE7 proteins.Methods The artificial HPV-16 mE7 gene was designed by codon modification, point mutation and gene shuffling then chemically synthesized and subcloned behind HPV-6b L2. HPV-6b L1 and L2-mE7 were expressed in insect cells by using Bac-to-Bac system. The generated cVLPs were purified by CsCl gradient ultracentrifuge and analyzed by immunoblot, electron microscope and haemagglutination assay.Results The HPV-6b L1 and L2-mE7 proteins were well expressed in insect cells and could selfassemble into cVLPs,whose diameter was about 55 nm and similar to that of HPV-6b L1/L2 VLPs. Intact cVLPs could be recognized by H6.M48 neutralizing monoclonal antibody and HPV-6b L2 polyclonal antibody, while the denatured cVLPs, but not the intact cVLPs, were reactive to HPV-16 E7 polyclonal antibody. HPV-6b L1/L2-mE7 cVLPs haemagglutinated mouse erythrocytes as efficiently as HPV-6b L1/L2 VLPs did.Conclusions The insertion of the 158 amino acid HPV-16 mE7 protein behind L2 did not disrupt the correct assembling of cVLPs. The morphological characteristics and haemagglutinating activity of cVLPs were similar to those of HPV-6b L1/L2 VLPs. The cVLPs retained conformational B cell epitopes of HPV-6 VLPs and HPV-16 mE7 protein had an internal location in the cVLPs. Therefore, large modified E7 protein with higher immunogenicity could be incorporated into cVLPs by fusing to the C-terminus of L2, which would help to improve the therapeutic effects of L1/L2-E7 cVLPs.

  5. PD-L2: A prognostic marker in chromophobe renal cell carcinoma?

    Science.gov (United States)

    Erlmeier, Franziska; Weichert, Wilko; Autenrieth, Michael; Wiedemann, Max; Schrader, Andres Jan; Hartmann, Arndt; Ivanyi, Philipp; Steffens, Sandra

    2017-05-01

    In the context of cancer immunotherapy, PD-1 as well as PD-L1 has been widely studied in renal cell carcinoma (RCC). PD-1 and PD-L1 play a significant role as prognostic markers in clear cell renal cell carcinoma. In contrast, little is known about PD-L2 expression patterns in RCC, especially in rarer subtypes. The aim of this study was to evaluate the prevalence, distribution and prognostic impact of PD-L2 expression in chromophobe (ch)RCC. Eighty-one patients who underwent renal surgery due to chRCC were retrospectively evaluated. Tumor specimens were analyzed for PD-L2 expression by immunohistochemistry. Expression data were associated with clinicopathological parameters and overall survival (OS). Twenty-three (28.4%) patients showed a PD-L2 > median (PD-L2 high) staining intensity. No significant association between clinicopathological parameters and PD-L2 expression was identified. A significant difference between 5- and 10-year OS in dependence of PD-L2 expression was found (PD-L2 low 96.4 and 87.7% vs. PD-L2 high 87.1 and 56%; log rank, p = 0.029). However, in multivariate analysis PD-L2 expression failed to be proofed as an independent prognostic factor. In conclusion, to our knowledge this is the first study evaluating the prognostic impact of PD-L2 in a considerably large cohort of chRCC. Our results showed a significant diminished OS in dependence of PD-L2 expression. This implicates that PD-L2 might play a role as prognostic marker in chRCC demanding further evaluation.

  6. Effects of task repetition on L2 oral performance Efeitos da repetição de tarefas na produção oral em L2

    OpenAIRE

    Kyria Rebeca Finardi

    2008-01-01

    This study departs from the assumption that speaking an L2 is a complex cognitive ability (FORTKAMP, 2000) whose execution seems to involve tradeoff effects among the different goals of speech production, mainly among fluency, accuracy and complexity (BYGATE, 1998, 1999, 2001b; FOSTER e SKEHAN, 1996; SKEHAN e FOSTER, 1995, 2001; SKEHAN, 1998). Bygate (2001b) studied the effects of task familiarity on L2 speech performance. He found that in repeating a narrative task there were gains in terms ...

  7. Assimilation of L2 vowels to L1 phonemes governs L2 learning in adulthood – A behavioral and ERP study

    Directory of Open Access Journals (Sweden)

    Mirko eGrimaldi

    2014-05-01

    Full Text Available According to the Perceptual Assimilation Model (PAM, acoustic similarity/dissimilarity between sounds of the second language (L2 and the native language (L1 governs L2 learnability in adulthood and predicts L2 sound perception by naïve listeners. We performed behavioral and neurophysiological experiments on two groups of university students at the first and fifth years of the English language curriculum and on a group of naïve listeners. Categorization and discrimination tests, as well as the mismatch negativity (MMN brain response to L2 sound changes, showed that the discriminatory capabilities of the students did not significantly differ from those of the naïve subjects. In line with the PAM model, we extend the findings of previous behavioral studies showing that, at the neural level, classroom instruction in adulthood relies on assimilation of L2 vowels to L1 phoneme categories and does not trigger improvement in L2 phonetic discrimination.

  8. Embedded aspect in L2 acquisition: Evidence from L1 Russian learners of Greek

    Directory of Open Access Journals (Sweden)

    Sviatlana Karpava

    2013-06-01

    Full Text Available This work investigates first language (L1 influence on the second language (L2 acquisition of aspect, comparing participants with homogeneous L1 background (Russian in Mainland Greece (L2 Standard Modern Greek and Cyprus (L2 Cypriot Greek, where verb complementation takes a finite form instead of an infinitival as is possible in Russian. Focus of the experimental study lies on embedded environments, which require only perfective aspect in Greek but allow either perfective or imperfective in Russian. The findings support the Full Transfer/Full Access Hypothesis, according to which aspect is part of Universal Grammar and L2 learners can reach native-like attainment due to access to it, while at the initial stage of L2 acquisition transfer from L1 into L2 takes place.

  9. An Introduction of Zoltán D?rnyei's L2 Motivational Theories%An Introduction of Zoltán Dörnyei's L2 Motivational Theories

    Institute of Scientific and Technical Information of China (English)

    王晓磊; 周密

    2016-01-01

    Professor Zoltán D?rnyei is an influential researcher of L2 learning motivation. Since 1990s, he put forward several important L2 learning motivational theories and made special contribution to this field. This paper introduces his four L2 learn-ing motivational theories:1)Three-level framework of L2 motivation;2) Process model of L2 motivation;3)The L2 Motivation-al Self System;4) Directed Motivational Currents (DMC).

  10. The Application of Bottom-up and Top-down Processing in L2 Listening Comprehension

    Institute of Scientific and Technical Information of China (English)

    温颖茜

    2008-01-01

    Listening comprehension is one of the four basic skills for language learning and is also one of the most difficult tasks L2 learners ever experienced.L2 listening comprehemion is a cognitvive process,in which listeners use both bottom-up andtop-downprocessing to comprehend the auraltext.Thepaper focmes on the applicationof the two approaches in L2 lis-tening comprehemiom

  11. Diction and Expression in Error Analysis Can Enhance Academic Writing of L2 University Students

    OpenAIRE

    Muhammad Sajid

    2016-01-01

    Without proper linguistic competence in English language, academic writing is one of the most challenging tasks, especially, in various genre specific disciplines by L2 novice writers. This paper examines the role of diction and expression through error analysis in English language of L2 novice writers’ academic writing in interdisciplinary texts of IT & Computer sciences and Business & Management sciences. Though the importance of vocabulary in L2 academic discourse is widely recognized, the...

  12. Effects of Different Reading Purposes on L2 Learners’IVA

    Institute of Scientific and Technical Information of China (English)

    WANG Wei

    2015-01-01

    According to the former studies, there are many factors having effects on second language (L2) learners’incidental vo⁃cabulary acquisition (IVA). This paper is aimed to reveal how reading a text with different purposes might affect IVA of L 2 learn⁃ers. The results of this study show that there is a closed relationship between the efficiency of IVA and reading purposes. Besides, it also has something to do with L2 learners’reading abilities.

  13. A Subspace Embedding Method in L2 Norm via Fast Cauchy Transform

    Directory of Open Access Journals (Sweden)

    Xu Xiang

    2013-01-01

    Full Text Available We propose a subspace embedding method via Fast Cauchy Transform (FCT in L2 norm. It is motivated by and complements the work of the subspace embedding method in Lp norm, for all p∈[1,∞] except p = 2, by K. L. Clarkson (ACM-SIAM, 2013. Unlike the traditionally used orthogonal basis in Johnson-Lindenstrauss (JL embedding, we employ the well-conditioned basis in L2 norm to obtain concentration property of FCT in L2 norm.

  14. Adult ESL Korean Readers' Responses about Their Reading in L1 Korean and L2 English

    Science.gov (United States)

    Kim, Misun

    2010-01-01

    In this research study I explore: (a) beliefs Korean ESL readers have about reading in L1 and L2 prior to the Retrospective Miscue Analysis (RMA) sessions, (b) how their beliefs about reading affect the way they read in L1 and L2 and their evaluation of themselves as readers in L1 and L2 reading, and (c) change of their beliefs about reading and…

  15. Working memory capacity and speech production in L2: evidences from a picture description task

    Directory of Open Access Journals (Sweden)

    Kyria Finardi

    2012-11-01

    Full Text Available This is an experimental study which aimed at investigating theralationsship between working memory capacity and measuresof L2 speech performance in a picture description task. The mainassumption underlying the present study was that L2 speaking isa complex cognitive task which is carried out within theconstraints of a limited-capacity system, namely, working memory.In this system, there are trade-off effects between the storage andprocessing functions of working memory just as in L2 speakingthere are trade-off effects among fluency, accuracy and complexitywhen L2 learners perform under processing pressure.

  16. A Study of the Differences Between Children's L1 and Adults'L2 in SLA

    Institute of Scientific and Technical Information of China (English)

    孙岩; 马炳军

    2015-01-01

    The differences between children's L1 acquisition and adults'L2 acquisition based on a qualitative analysis are dis-cussed and compared.Through systematic review of the relevant literature in light of the theories of L1 and L2 acquisition between children and adults,and analysis of the factors both influencing children's L1 and adults'L2 acquisition.The findings show that two different acquisitions are distinguished in such aspects as in acquisition age,device,mode,environment and motivation,which conclude that children's L1 acquisition is effortless while adults'L2 acquisition is painful.

  17. Points of Transition: Understanding the Constructed Identities of L2 Learners/Users across Time and Space

    Science.gov (United States)

    Adawu, Anthony; Martin-Beltran, Melinda

    2012-01-01

    Using sociocultural and poststructuralist theoretical lenses, this study examines the narrative construction of language-learner identity across time and space. We applied cross-narrative methodologies to analyze language-learning autobiographies and interview data from three English users who had recently transitioned to a U.S. context for…

  18. The RNA-binding protein, ZFP36L2, influences ovulation and oocyte maturation.

    Directory of Open Access Journals (Sweden)

    Christopher B Ball

    Full Text Available ZFP36L2 protein destabilizes AU-rich element-containing transcripts and has been implicated in female fertility. In the C57BL/6NTac mouse, a mutation in Zfp36l2 that results in the decreased expression of a form of ZFP36L2 in which the 29 N-terminal amino acid residues have been deleted, ΔN-ZFP36L2, leads to fertilized eggs that arrest at the two-cell stage. Interestingly, homozygous ΔN-Zfp36l2 females in the C57BL/6NTac strain release 40% fewer eggs than the WT littermates (Ramos et al., 2004, suggesting an additional defect in ovulation and/or oocyte maturation. Curiously, the same ΔN-Zfp36l2 mutation into the SV129 strain resulted in anovulation, prompting us to investigate a potential problem in ovulation and oocyte maturation. Remarkably, only 20% of ΔN-Zfp36l2 oocytes in the 129S6/SvEvTac strain matured ex vivo, suggesting a defect on the oocyte meiotic maturation process. Treatment of ΔN-Zfp36l2 oocytes with a PKA inhibitor partially rescued the meiotic arrested oocytes. Furthermore, cAMP levels were increased in ΔN-Zfp36l2 oocytes, linking the cAMP/PKA pathway and ΔN-Zfp36l2 with meiotic arrest. Since ovulation and oocyte maturation are both triggered by LHR signaling, the downstream pathway was investigated. Adenylyl cyclase activity was increased in ΔN-Zfp36l2 ovaries only upon LH stimulation. Moreover, we discovered that ZFP36L2 interacts with the 3'UTR of LHR mRNA and that decreased expression levels of Zfp36l2 correlates with higher levels of LHR mRNA in synchronized ovaries. Furthermore, overexpression of ZFP36L2 decreases the endogenous expression of LHR mRNA in a cell line. Therefore, we propose that lack of the physiological down regulation of LHR mRNA levels by ZFP36L2 in the ovaries is associated with anovulation and oocyte meiotic arrest.

  19. Learning to perceive and recognize a second language: the L2LP model revised

    Science.gov (United States)

    van Leussen, Jan-Willem; Escudero, Paola

    2015-01-01

    We present a test of a revised version of the Second Language Linguistic Perception (L2LP) model, a computational model of the acquisition of second language (L2) speech perception and recognition. The model draws on phonetic, phonological, and psycholinguistic constructs to explain a number of L2 learning scenarios. However, a recent computational implementation failed to validate a theoretical proposal for a learning scenario where the L2 has less phonemic categories than the native language (L1) along a given acoustic continuum. According to the L2LP, learners faced with this learning scenario must not only shift their old L1 phoneme boundaries but also reduce the number of categories employed in perception. Our proposed revision to L2LP successfully accounts for this updating in the number of perceptual categories as a process driven by the meaning of lexical items, rather than by the learners' awareness of the number and type of phonemes that are relevant in their new language, as the previous version of L2LP assumed. Results of our simulations show that meaning-driven learning correctly predicts the developmental path of L2 phoneme perception seen in empirical studies. Additionally, and to contribute to a long-standing debate in psycholinguistics, we test two versions of the model, with the stages of phonemic perception and lexical recognition being either sequential or interactive. Both versions succeed in learning to recognize minimal pairs in the new L2, but make diverging predictions on learners' resulting phonological representations. In sum, the proposed revision to the L2LP model contributes to our understanding of L2 acquisition, with implications for speech processing in general. PMID:26300792

  20. Transcription factor NFE2L2/NRF2 is a regulator of macroautophagy genes

    Science.gov (United States)

    Pajares, Marta; Jiménez-Moreno, Natalia; García-Yagüe, Ángel J.; Escoll, Maribel; de Ceballos, María L.; Van Leuven, Fred; Rábano, Alberto; Yamamoto, Masayuki; Rojo, Ana I.; Cuadrado, Antonio

    2016-01-01

    ABSTRACT Autophagy is a highly coordinated process that is controlled at several levels including transcriptional regulation. Here, we identify the transcription factor NFE2L2/NRF2 (nuclear factor, erythroid 2 like 2) as a regulator of autophagy gene expression and its relevance in a mouse model of Alzheimer disease (AD) that reproduces impaired APP (amyloid β precursor protein) and human (Hs)MAPT/TAU processing, clearance and aggregation. We screened the chromatin immunoprecipitation database ENCODE for 2 proteins, MAFK and BACH1, that bind the NFE2L2-regulated enhancer antioxidant response element (ARE). Using a script generated from the JASPAR's consensus ARE sequence, we identified 27 putative AREs in 16 autophagy-related genes. Twelve of these sequences were validated as NFE2L2 regulated AREs in 9 autophagy genes by additional ChIP assays and quantitative RT-PCR on human and mouse cells after NFE2L2 activation with sulforaphane. Mouse embryo fibroblasts of nfe2l2-knockout mice exhibited reduced expression of autophagy genes, which was rescued by an NFE2L2 expressing lentivirus, and impaired autophagy flux when exposed to hydrogen peroxide. NFE2L2-deficient mice co-expressing HsAPPV717I and HsMAPTP301L, exhibited more intracellular aggregates of these proteins and reduced neuronal levels of SQSTM1/p62, CALCOCO2/NDP52, ULK1, ATG5 and GABARAPL1. Also, colocalization of HsAPPV717I and HsMAPTP301L with the NFE2L2-regulated autophagy marker SQSTM1/p62 was reduced in the absence of NFE2L2. In AD patients, neurons expressing high levels of APP or MAPT also expressed SQSTM1/p62 and nuclear NFE2L2, suggesting their attempt to degrade intraneuronal aggregates through autophagy. This study shows that NFE2L2 modulates autophagy gene expression and suggests a new strategy to combat proteinopathies. PMID:27427974

  1. Learning to perceive and recognize a second language: the L2LP model revised

    Directory of Open Access Journals (Sweden)

    Jan-Willem eVan Leussen

    2015-08-01

    Full Text Available We present a test of a revised version of the Second Language Linguistic Perception (L2LP model, a computational model of the acquisition of second language (L2 speech perception and recognition. The model draws on phonetic, phonological and psycholinguistic constructs to explain a number of L2 learning scenarios. However, a recent computational implementation failed to validate a theoretical proposal for a learning scenario where the L2 has less phonemic categories than the native language (L1 along a given acoustic continuum. According to the L2LP, learners faced with this learning scenario must not only shift their old L1 phoneme boundaries but also reduce the number of categories employed in perception. Our proposed revision to L2LP successfully accounts for this updating in the number of perceptual categories as a process driven by the meaning of lexical items, rather than by the learners’ awareness of the number and type of phonemes that are relevant in their new language, as the previous version of L2LP assumed. Results of our simulations show that meaning-driven learning correctly predicts the developmental path of L2 phoneme perception seen in empirical studies. Additionally, and to contribute to a long-standing debate in psycholinguistics, we test two versions of the model, with the stages of phonemic perception and lexical recognition being either sequential or interactive. Both versions succeed in learning to recognize minimal pairs in the new L2, but make diverging predictions on learners' resulting phonological representations. In sum, the proposed revision to the L2LP model contributes to our understanding of L2 acquisition, with implications for speech processing in general.

  2. Learning to perceive and recognize a second language: the L2LP model revised.

    Science.gov (United States)

    van Leussen, Jan-Willem; Escudero, Paola

    2015-01-01

    We present a test of a revised version of the Second Language Linguistic Perception (L2LP) model, a computational model of the acquisition of second language (L2) speech perception and recognition. The model draws on phonetic, phonological, and psycholinguistic constructs to explain a number of L2 learning scenarios. However, a recent computational implementation failed to validate a theoretical proposal for a learning scenario where the L2 has less phonemic categories than the native language (L1) along a given acoustic continuum. According to the L2LP, learners faced with this learning scenario must not only shift their old L1 phoneme boundaries but also reduce the number of categories employed in perception. Our proposed revision to L2LP successfully accounts for this updating in the number of perceptual categories as a process driven by the meaning of lexical items, rather than by the learners' awareness of the number and type of phonemes that are relevant in their new language, as the previous version of L2LP assumed. Results of our simulations show that meaning-driven learning correctly predicts the developmental path of L2 phoneme perception seen in empirical studies. Additionally, and to contribute to a long-standing debate in psycholinguistics, we test two versions of the model, with the stages of phonemic perception and lexical recognition being either sequential or interactive. Both versions succeed in learning to recognize minimal pairs in the new L2, but make diverging predictions on learners' resulting phonological representations. In sum, the proposed revision to the L2LP model contributes to our understanding of L2 acquisition, with implications for speech processing in general.

  3. Lepton flavour violating decays of $\\mu$ and $\\tau$ lepton in a gauge group $SU_L(2)\\times SU_R(2)\\times SU_l(2)$

    CERN Document Server

    Fayyazuddin,

    2016-01-01

    A model for electroweak unification based on gauge group $ SU_L(2)\\times SU_R(2)\\times SU_l(2) $ for leptons is formulated. The group $SU_l(2)$ is in the lepton space.The left handed leptons and anti-leptons are assigned to the fundamental representation $(2,2,\\bar{2})$ of the group.The left- right symmetric gauge group $ SU_L(2)\\times SU_R(2)\\times U_{Y_1}(1) $ is contained in the above group for leptons. Out of three vector bossons $ Y_\\mu^\\pm $,$Y_{3\\mu}$ of $SU_l(2)$,the charged vector bosons $Y_\\mu^\\pm$ mediate the lepton number violating $ \\mu$ and $\\tau$ decays. The neutral vector bosson $ Y_{3\\mu}$ with coupling constant $ g_{Y}$ plays the same role as the vector bosson $B_{1\\mu}$ with coupling constant $g_1$ associated with Abelian part $ U_{Y_1}(1)$ with $Y_1=\\mp1$ for leptons and anti leptons. The left handed quarks and anti quarks are assigned to representations (2,1) and (1,2) with $Y_1=\\pm \\frac{1}{3}$ of the left-right symmetric gauge group. The lepton number violating $\\mu~and~\\tau$ decays sim...

  4. 哺乳动物FoxL2基因的分子进化分析%Molecular Evolution Analysis for Mammal FoxL2 Gene

    Institute of Scientific and Technical Information of China (English)

    刘丽丽; 刘静; 张向伟; 黄林艳; 李蓉; 李成磊; 王勤

    2015-01-01

    本研究以FoxL2基因为研究对象,选取GenBank公布的26个物种的FoxL2基因氨基酸序列,代表脊椎动物中5纲15目21科24属,重点分析哺乳动物中该基因的结构与功能相关性以及其系统发育情况.结果表明:26条FoxL2基因序列存在非常保守的forkhead结构域,哺乳类比非哺乳动物多出丙氨酸、甘氨酸及脯氨酸重复区,其中多聚丙氨酸束的缩短可能与Ⅰ型BPES相关,而多聚丙氨酸束的延伸使核内蛋白错位和细胞质聚集导致Ⅱ型BPES.FoxL2含有较多磷酸化位点,推测其在体内的活性可能是通过磷酸化调控的.FoxL2基因氨基酸序列构建的系统发育树中亲缘关系较近的物种能够较好的聚在一起.

  5. Investigating L2 spoken English through the role play learner corpus

    Directory of Open Access Journals (Sweden)

    Andrea Nava

    2011-04-01

    Full Text Available We describe an exploratory study carried out within the University of Milan, Department of English the aim of which was to analyse features of the spoken English of first-year Modern Languages undergraduates. We compiled a learner corpus, the “Role Play” corpus, which consisted of 69 role-play interactions in English carried out by first-year students at B1+-B2 levels according to the Common European Framework of Reference. The analysis focused on the students’ use of two features of spoken English grammar, tails and the discourse markers ‘yes’ and ‘yeah’. Instances of these features from the data were compared with examples of British native speaker, learner and Italian native speaker usage. Preliminary findings pointed to the role of the students’ first language, L2 proficiency and specific task features in the range and frequency of these phenomena as well as in the functions they deployed in the spoken discourse of the informants.

  6. Second Language Cyber Rhetoric: A Study of Chinese L2 Writers in an Online Usenet Group

    Directory of Open Access Journals (Sweden)

    Joel Bloch

    2004-09-01

    Full Text Available It has been argued that the expectations of traditional L2 writing classroom can be problematic for Chinese students, particularly in the area of argumentation and critical thinking. On the other hand, writing on the Internet has been shown to be substantially different in ways that may liberate the students from the constraints of the classroom. This argument, however, has typically focused on American writers, ignoring how cyberspace is being appropriated by those outside of the Western tradition of rhetoric. In this study, I examine how Chinese writers use the Internet as an alternative writing space to produce a rhetoric that incorporates traditional Chinese rhetorical forms expressed in English. The study focuses on how a group of Chinese writers respond on the Internet to a television segment accusing the Chinese government of planting spies. I found that the Chinese writers use the Internet to build a collective response to the television show using a variety of rhetorical strategies, even to the point of forcing the television network to meet with them. By situating their arguments in the tradition of Chinese rhetoric, I found that these alternative forms of writing found in cyberspace are affected by the traditions of Chinese rhetoric.

  7. Importanza della diversità diatopica nell’insegnamento della lingua spagnola come L2

    Directory of Open Access Journals (Sweden)

    Silvia Lafuente

    2013-03-01

    Full Text Available The syncretic cultural identity, in which the Spanish language and its linguistic hegemony are grounded and have reflected its political hegemony, led Spain to take on a predominant role in standardization over the centuries. However, the present situation of the Spanish language is characterized by pluricentrism covering the vast territory in which the language is spoken. This means that a number of cen- ters have set up prestigious standard models providing norms for a country or region. Therefore, a fair enactment of this polycentrism requires national norms, different ways of codification of the Spanish language, answers to geographical and social forms which have split after a common departure and the idea that the varieties of the Spanish language fulfill speakers’ different expressive requirements and help to enhance national identities, in the face of the domination of the peninsular model. This point of view must guide linguistic research, methodology in lexicography, school grammar, translation of foreign languages and especially the teaching of Spanish as L2.

  8. Applying Dynamical Systems Theory to Optimize Libration Point Orbit Stationkeeping Maneuvers for WIND

    Science.gov (United States)

    Brown, Jonathan M.; Petersen, Jeremy D.

    2014-01-01

    NASA's WIND mission has been operating in a large amplitude Lissajous orbit in the vicinity of the interior libration point of the Sun-Earth/Moon system since 2004. Regular stationkeeping maneuvers are required to maintain the orbit due to the instability around the collinear libration points. Historically these stationkeeping maneuvers have been performed by applying an incremental change in velocity, or (delta)v along the spacecraft-Sun vector as projected into the ecliptic plane. Previous studies have shown that the magnitude of libration point stationkeeping maneuvers can be minimized by applying the (delta)v in the direction of the local stable manifold found using dynamical systems theory. This paper presents the analysis of this new maneuver strategy which shows that the magnitude of stationkeeping maneuvers can be decreased by 5 to 25 percent, depending on the location in the orbit where the maneuver is performed. The implementation of the optimized maneuver method into operations is discussed and results are presented for the first two optimized stationkeeping maneuvers executed by WIND.

  9. L1-L2 Convergence in Clausal Packaging in Japanese and English

    Science.gov (United States)

    Brown, Amanda; Gullberg, Marianne

    2013-01-01

    This study investigates L1-L2 convergence among bilinguals at an intermediate (CEFR-B2) level of L2 proficiency, focusing on the clausal packaging of Manner and Path of motion. Previous research has shown cross-linguistic differences between English and Japanese in this domain (Allen et al., 2003; Kita & Ozyurek, 2003, though note Brown &…

  10. The Role of Phonology and Phonetics in L2 Kanji Learning

    Science.gov (United States)

    Hagiwara, Akiko

    2016-01-01

    This study explores whether emphasizing the phonetic components of "kanji," Chinese characters used in Japanese, facilitates second language (L2) learners' novel character learning. Previous L2 studies on Chinese characters indicate that phonology plays a major part in word identification. However, this view remains controversial,…

  11. Estimativos L^2 para una clase de operadores pseudodiferenciales definidos en el toro

    Directory of Open Access Journals (Sweden)

    Duván Cardona

    2013-12-01

    Full Text Available En este trabajo se establecen estimativos L 2 para operadores pseudodiferenciales definidos en el toro. Los operadores considerados surgen del estudio de operadores entre grupos abelianos localmente compactos. Abstract. In this work we establish L 2 estimates from pseudo-differential operators defined on the torus. Such operators arise from the study of operators on locally compact abelian groups.

  12. Looking for the Big Picture: Macrostrategies for L2 Teacher Observation and Feedback

    Science.gov (United States)

    Salas, Spencer; Mercado, Leonardo

    2010-01-01

    While an extensive body of literature in TESOL studies the different paradigms that drive second language (L2) teachers' conceptualizations of their professional identities and practice, there is still a need for more research into how L2 supervisors construct the realities of supervision and how their interpretations of those realities inform…

  13. Native Speakers’ Perceptions of Fluency and Accent in L2 Speech

    NARCIS (Netherlands)

    Pinget, A.C.H.; Bosker, H.R.; Quené, H.; de Jong, N.H.

    2014-01-01

    Oral fluency and foreign accent distinguish L2 from L1 speech production. In language testing practices, both fluency and accent are usually assessed by raters. This study investigates what exactly native raters of fluency and accent take into account when judging L2. Our aim is to explore the relat

  14. L2-proficiency-dependent laterality shift in structural connectivity of brain language pathways

    NARCIS (Netherlands)

    Xiang, H.; Leeuwen, T.M. van; Dediu, D.; Roberts, L.; Norris, D.G.; Hagoort, P.

    2015-01-01

    Diffusion tensor imaging (DTI) and a longitudinal language learning approach were applied to investigate the relationship between the achieved second language (L2) proficiency during L2 learning and the reorganization of structural connectivity between core language areas. Language proficiency tests

  15. L1 Use in L2 Vocabulary Learning: Facilitator or Barrier

    Science.gov (United States)

    Liu, Jing

    2008-01-01

    Based on empirical research and qualitative analysis, this paper aims to explore the effects of L1 use on L2 vocabulary teaching. The results show that, during L2 vocabulary teaching process, the proper application of L1 can effectively facilitate the memorization of new words, and the bilingual method (both English explanation and Chinese…

  16. The Effects of Hypertext Glosses on L2 Vocabulary Acquisition: A Meta-Analysis

    Science.gov (United States)

    Yun, Jee Hwan

    2010-01-01

    In the field of second language acquisition (SLA), "comprehensible input" (Krashen, 1985) has been considered a critical factor to help learners acquire foreign and second languages (L2). From this perspective, the notion of extensive or free voluntary reading (Day & Bamford, 1998; Krashen, 1993) has emerged that L2 learners should be given more…

  17. The Effects of Corrective Feedback on Instructed L2 Speech Perception

    Science.gov (United States)

    Lee, Andrew H.; Lyster, Roy

    2016-01-01

    To what extent do second language (L2) learners benefit from instruction that includes corrective feedback (CF) on L2 speech perception? This article addresses this question by reporting the results of a classroom-based experimental study conducted with 32 young adult Korean learners of English. An instruction-only group and an instruction + CF…

  18. ESP Students' Views on Online Language Resources for L2 Text Production Purposes

    Science.gov (United States)

    Kozlova, Inna; Presas, Marisa

    2013-01-01

    The use of online language resources for L2 text production purposes is a recent phenomenon and has not yet been studied in depth. Increasing availability of new online resources seems to be changing the very nature of L2 text production. The traditional dictionary, hitherto a default resource to help with language doubts, is being left behind…

  19. Older Learners in SLA Research: A First Look at Working Memory, Feedback, and L2 Development

    Science.gov (United States)

    Mackey, Alison; Sachs, Rebecca

    2012-01-01

    A great deal of research into second-language (L2) development focuses on the role of cognitive factors and other individual differences. Studies of children and prime-of-life adult L2 learners suggest that differences exist in the learning processes of these groups. However, to date, little empirical work has been conducted with older adult…

  20. A Study of Relationships between L1 Pragmatic Transfer and L2 Proficiency

    Science.gov (United States)

    Bu, Jiemin

    2012-01-01

    Studies in interlanguage pragmatics have shown that L2 learners' proficiency has an influence on the occurrences of L1 pragmatic transfer. However, questions remain whether the relationship between L1 pragmatic transfer and L2 proficiency is positive or negative. This paper is designed to study L1 pragmatic transfer in requests made by Chinese…

  1. Differences in process and process-product relations in L2 writing

    NARCIS (Netherlands)

    van Weijen, D.; van den Bergh, H.; Rijlaarsdam, G.; Sanders, T.

    2008-01-01

    This study examines whether writers vary how they write under influence of the changing task situation when writing in a second language (L2) and, if so, whether differences in the way they write are related to variations in text quality. Twenty first year students wrote four texts each in their L2

  2. Twelve Activities for Teaching the Pragmatics of Complaining to L2 Learners

    Science.gov (United States)

    Hilliard, Amanda

    2017-01-01

    Pragmatic competence, or the ability to use language appropriately in a variety of contexts, is a critical skill for communication in a second language (L2). Thus, teaching that focuses on developing students' abilities to communicate effectively in an L2 must also include a focus on developing students' pragmatic competence. This article…

  3. L1 use during L2 writing: an empirical study of a complex phenomenon

    NARCIS (Netherlands)

    van Weijen, D.; van den Bergh, H.; Rijlaarsdam, G.; Sanders, T.

    2009-01-01

    This study examined writers’ use of their first language (L1) while writing in their second language (L2). Twenty students each wrote four short argumentative essays in their L1 (Dutch) and four in their L2 (English) under think-aloud conditions. We analysed whether L1 use varied between writers and

  4. Perceptions of the Difficulties of Postgraduate L2 Thesis Students Writing the Discussion Section

    Science.gov (United States)

    Bitchener, John; Basturkmen, Helen

    2006-01-01

    In postgraduate study, students including L2 students are often required to write a thesis and, as a growing literature reveals, L2 students often experience difficulties in the writing of this genre. While most of this research has involved surveys (questionnaires and interviews) and case studies of supervisor perceptions, only a few studies have…

  5. Web-Based Collaborative Writing in L2 Contexts: Methodological Insights from Text Mining

    Science.gov (United States)

    Yim, Soobin; Warschauer, Mark

    2017-01-01

    The increasingly widespread use of social software (e.g., Wikis, Google Docs) in second language (L2) settings has brought a renewed attention to collaborative writing. Although the current methodological approaches to examining collaborative writing are valuable to understand L2 students' interactional patterns or perceived experiences, they can…

  6. Societal Responses to Adult Difficulties in L2 Acquisition: Toward an Evolutionary Perspective on Language Acquisition

    Science.gov (United States)

    Schumann, John H.

    2013-01-01

    It is generally accepted that second language (L2) acquisition becomes more difficult as one grows older and that success in adult L2 acquisition is highly variable. Nevertheless, humans in language contact situations have to cope with intergroup communication. This article examines the ways society has responded to this challenge. It describes…

  7. The Influence of Schema and Cultural Difference on L1 and L2 Reading

    Science.gov (United States)

    Yang, Shi-sheng

    2010-01-01

    Reading in L1 shares numerous basic elements with reading in L2, and the processes also differ greatly. Intriguing questions involve whether there are two parallel cognitive processes at work, or whether there are processing strategies that accommodate both L1 and L2. This paper examines how reading in L1 is different from and similar to reading…

  8. L1 use during L2 writing: an empirical study of a complex phenomenon

    NARCIS (Netherlands)

    D. van Weijen; H. van den Bergh; G. Rijlaarsdam; T. Sanders

    2009-01-01

    This study examined writers’ use of their first language (L1) while writing in their second language (L2). Twenty students each wrote four short argumentative essays in their L1 (Dutch) and four in their L2 (English) under think-aloud conditions. We analysed whether L1 use varied between writers and

  9. The Role of Noticing and Attention in the Acquisition of L2 Grammatical Knowledge

    Institute of Scientific and Technical Information of China (English)

    李洁慧

    2012-01-01

    The discussion in the literature on the question of how L2 grammatical knowledge is acquired has been influenced by the issue of noticing and attention. This article gives an overview of the important role of noticing and attention in L2 acquisition.

  10. L1 English/L2 Spanish: Orthography-Phonology Activation without Contrasts

    Science.gov (United States)

    Shea, Christine

    2017-01-01

    We consider how orthography activates sounds that are in a noncontrastive relationship in the second language (L2) and for which only one variant exists in the first language (L1). Participants were L1 English / L2 Spanish and native Spanish listeners. Intervocalically, Spanish graphemes "b d g" correspond phonetically to stops and…

  11. The Role of Phonology and Phonetics in L2 Kanji Learning

    Science.gov (United States)

    Hagiwara, Akiko

    2016-01-01

    This study explores whether emphasizing the phonetic components of "kanji," Chinese characters used in Japanese, facilitates second language (L2) learners' novel character learning. Previous L2 studies on Chinese characters indicate that phonology plays a major part in word identification. However, this view remains controversial,…

  12. Listening in a Multilingual World: The Challenges of Second Language (L2) Listening

    Science.gov (United States)

    Rost, Michael

    2014-01-01

    Research into language acquisition and oral language use was examined in order to identify key factors that contribute to the successful acquisition of second language (L2) listening ability. The factors were grouped into three major domains: affective, cognitive, and interpersonal. It is claimed that in each domain, proficient L2 listeners have…

  13. Processing Strategies by Beginning L2 Learners of English and Spanish: A Crosslinguistic Study

    Science.gov (United States)

    Brandl, Anel

    2013-01-01

    A central issue in second language acquisition (SLA) research is the relationship between morphosyntactic and lexical-semantic knowledge among L2 learners. It has been proposed that, L2 language acquisition starts with transfer of L1 semantic and morphosyntactic processing strategies; however, it has been observed that, at lower proficiency…

  14. Long-Term Crosslinguistic Transfer of Skills from L1 to L2

    Science.gov (United States)

    Sparks, Richard; Patton, Jon; Ganschow, Leonore; Humbach, Nancy

    2009-01-01

    This study investigated the relationship of first language (L1) skills in elementary school and second language (L2) learning in high school. Students classified as high-, average-, and low-proficiency L2 learners were compared on L1 achievement measures of reading, spelling, vocabulary, phonological awareness, and listening comprehension…

  15. L2 Academic Discourse Socialization through Oral Presentations: An Undergraduate Student's Learning Trajectory in Study Abroad

    Science.gov (United States)

    Kobayashi, Masaki

    2016-01-01

    The present study provides an in-depth, longitudinal account of an undergraduate student's L2 discourse socialization in an academic exchange program in Canada. By invoking Rogoff's (1995) notion of participatory appropriation, this qualitative case study examined an L2 student's task-related strategies and performance as they evolved over time in…

  16. Concurrent Data Elicitation Procedures, Processes, and the Early Stages of L2 Learning: A Critical Overview

    Science.gov (United States)

    Leow, Ronald P.; Grey, Sarah; Marijuan, Silvia; Moorman, Colleen

    2014-01-01

    Given the current methodological interest in eliciting direct data on the cognitive processes L2 learners employ as they interact with L2 data during the early stages of the learning process, this article takes a critical and comparative look at three concurrent data elicitation procedures currently employed in the SLA literature: Think aloud (TA)…

  17. L2 Reading Comprehension and Its Correlates: A Meta-Analysis

    Science.gov (United States)

    Jeon, Eun Hee; Yamashita, Junko

    2014-01-01

    The present meta-analysis examined the overall average correlation (weighted for sample size and corrected for measurement error) between passage-level second language (L2) reading comprehension and 10 key reading component variables investigated in the research domain. Four high-evidence correlates (with 18 or more accumulated effect sizes: L2

  18. L2 and L3 Ultimate Attainment: An Investigation of Two Parameters

    Science.gov (United States)

    Hermas, Abdelkader

    2014-01-01

    This study considers the upper limit of ultimate attainment in the L2 French and L3 English of trilingual learners. The learners are native speakers of Moroccan Arabic who started learning L2 French at eight and L3 English at 16. They are advanced in both languages. Four constructions representing the verb movement and null subject parameter were…

  19. Dispersion and Frequency: Is There Any Difference as Regards Their Relation to L2 Vocabulary Gains?

    Science.gov (United States)

    Alcaraz-Mármol, Gema

    2015-01-01

    Despite the current importance given to L2 vocabulary acquisition in the last two decades, considerable deficiencies are found in L2 students' vocabulary size. One of the aspects that may influence vocabulary learning is word frequency. However, scholars warn that frequency may lead to wrong conclusions if the way words are distributed is ignored.…

  20. Beyond barriers : Complexity, accuracy, and fluency in long-term L2 speakers' speech

    NARCIS (Netherlands)

    Lahmann, Cornelia Milli Marie Antonia

    2015-01-01

    It remains to be a puzzling question why some people are more successful in learning a second language (L2) than others and under which conditions. In my dissertation I studied the effects of several factors, including the starting age of learning a L2, the amount of continued exposure to the first

  1. Working Memory Effects in the L2 Processing of Ambiguous Relative Clauses

    Science.gov (United States)

    Hopp, Holger

    2014-01-01

    This article investigates whether and how L2 sentence processing is affected by memory constraints that force serial parsing. Monitoring eye movements, we test effects of working memory on L2 relative-clause attachment preferences in a sample of 75 late-adult German learners of English and 25 native English controls. Mixed linear regression…

  2. Concatenative and Nonconcatenative Plural Formation in L1, L2, and Heritage Speakers of Arabic

    Science.gov (United States)

    Albirini, Abdulkafi; Benmamoun, Elabbas

    2014-01-01

    This study compares Arabic L1, L2, and heritage speakers' (HS) knowledge of plural formation, which involves concatenative and nonconcatenative modes of derivation. Ninety participants (divided equally among L1, L2, and heritage speakers) completed two oral tasks: a picture naming task (to measure proficiency) and a plural formation task. The…

  3. Effects of Age of L2 Acquisition on L1 Event Conceptualization Patterns

    Science.gov (United States)

    Bylund, Emanuel

    2009-01-01

    This study explores the effects that the age of onset (AO) of second language (L2) acquisition exerts on the attrition of first language (L1) event conceptualization patterns. The subjects studied are L1 Spanish-L2 Swedish bilinguals living in Sweden. The specific research questions addressed in the study concern the role of AO in endpoint…

  4. Emergent L2 German Writing Ability in a Curricular Context: A Longitudinal Study of Grammatical Metaphor

    Science.gov (United States)

    Byrnes, Heidi

    2009-01-01

    The paper reports on a study of emergent adult instructed L2 German writing ability in a college-level program that developed an explicit curriculum-based approach to supporting L2 writing. It uses systemic-functional linguistics (SFL) as its theoretical framework and traces writing development through a central construct in the theory, the…

  5. L2-Proficiency-Dependent Laterality Shift in Structural Connectivity of Brain Language Pathways.

    Science.gov (United States)

    Xiang, Huadong; van Leeuwen, Tessa Marije; Dediu, Dan; Roberts, Leah; Norris, David G; Hagoort, Peter

    2015-08-01

    Diffusion tensor imaging (DTI) and a longitudinal language learning approach were applied to investigate the relationship between the achieved second language (L2) proficiency during L2 learning and the reorganization of structural connectivity between core language areas. Language proficiency tests and DTI scans were obtained from German students before and after they completed an intensive 6-week course of the Dutch language. In the initial learning stage, with increasing L2 proficiency, the hemispheric dominance of the Brodmann area (BA) 6-temporal pathway (mainly along the arcuate fasciculus) shifted from the left to the right hemisphere. With further increased proficiency, however, lateralization dominance was again found in the left BA6-temporal pathway. This result is consistent with reports in the literature that imply a stronger involvement of the right hemisphere in L2 processing especially for less proficient L2 speakers. This is the first time that an L2 proficiency-dependent laterality shift in the structural connectivity of language pathways during L2 acquisition has been observed to shift from left to right and back to left hemisphere dominance with increasing L2 proficiency. The authors additionally find that changes in fractional anisotropy values after the course are related to the time elapsed between the two scans. The results suggest that structural connectivity in (at least part of) the perisylvian language network may be subject to fast dynamic changes following language learning.

  6. Diction and Expression in Error Analysis Can Enhance Academic Writing of L2 University Students

    Science.gov (United States)

    Sajid, Muhammad

    2016-01-01

    Without proper linguistic competence in English language, academic writing is one of the most challenging tasks, especially, in various genre specific disciplines by L2 novice writers. This paper examines the role of diction and expression through error analysis in English language of L2 novice writers' academic writing in interdisciplinary texts…

  7. Differences in process and process-product relations in L2 writing

    NARCIS (Netherlands)

    van Weijen, D.; van den Bergh, H.; Rijlaarsdam, G.; Sanders, T.

    2008-01-01

    This study examines whether writers vary how they write under influence of the changing task situation when writing in a second language (L2) and, if so, whether differences in the way they write are related to variations in text quality. Twenty first year students wrote four texts each in their L2

  8. The Effect of Technology-Supported Co-Sharing on L2 Vocabulary Strategy Development

    Science.gov (United States)

    Lan, Yu-Ju

    2013-01-01

    Strategies play an important role in learning a second or foreign language (L2). The aim of the current study was to develop and evaluate a co-sharing-based strategy learning system for L2 vocabulary learning known as "Mywordtools." Mywordtools is designed specifically for lexical learning, enabling learners to use the currently…

  9. The Development of Complexity, Accuracy and Fluency in the Written Production of L2 French

    Science.gov (United States)

    Gunnarsson, Cecilia

    2012-01-01

    The present longitudinal case study investigated the development of fluency, complexity and accuracy--and the possible relationships between them--in the written production of L2 French. We assessed fluency and complexity in five intermediate learners by means of conventional indicators for written L2 (cf. Wolfe-Quintero et al. 1998), while…

  10. Beyond barriers : Complexity, accuracy, and fluency in long-term L2 speakers' speech

    NARCIS (Netherlands)

    Lahmann, Cornelia Milli Marie Antonia

    2015-01-01

    It remains to be a puzzling question why some people are more successful in learning a second language (L2) than others and under which conditions. In my dissertation I studied the effects of several factors, including the starting age of learning a L2, the amount of continued exposure to the first

  11. Isolated and Integrated Form-Focused Instruction: Effects on Different Types of L2 Knowledge

    Science.gov (United States)

    Spada, Nina; Jessop, Lorena; Tomita, Yasuyo; Suzuki, Wataru; Valeo, Antonella

    2014-01-01

    In this study we compared the effects of two types of form-focused instruction (FFI) on second language (L2) learning and their potential contributions to the development of different types of L2 knowledge. Both types of instruction were pre-emptive in nature, that is planned and teacher generated. In Integrated FFI attention to form was embedded…

  12. Word Boundaries in L2 Speech: Evidence from Polish Learners of English

    Science.gov (United States)

    Schwartz, Geoffrey

    2016-01-01

    Acoustic and perceptual studies investgate B2-level Polish learners' acquisition of second language (L2) English word-boundaries involving word-initial vowels. In production, participants were less likely to produce glottalization of phrase-medial initial vowels in L2 English than in first language (L1) Polish. Perception studies employing word…

  13. Unconventional Expressions: Productive Syntax in the L2 Acquisition of Formulaic Language

    Science.gov (United States)

    Bardovi-Harlig, Kathleen; Stringer, David

    2017-01-01

    This article presents a generative analysis of the acquisition of formulaic language as an alternative to current usage-based proposals. One influential view of the role of formulaic expressions in second language (L2) development is that they are a bootstrapping mechanism into the L2 grammar; an initial repertoire of constructions allows for…

  14. The Role of Hypercorrection in the Acquisition of L2 Phonemic Contrasts

    Science.gov (United States)

    Eckman, Fred R.; Iverson, Gregory K.; Song, Jae Yung

    2013-01-01

    This article reports empirical findings from an ongoing investigation into the acquisition of second-language (L2) phonemic contrasts. Specifically, we consider the status and role of the phenomenon of hypercorrection in the various stages through which L2 learners develop and internalize a target language (TL) contrast. We adopt the prevailing…

  15. Exploring Learner Factors in Second Language (L2) Incidental Vocabulary Acquisition through Reading

    Science.gov (United States)

    Zhao, Aiping; Guo, Ying; Biales, Carrie; Olszewski, Arnold

    2016-01-01

    This study examined the predictive role of several learner factors in second language (L2) incidental vocabulary acquisition through reading: L2 proficiency, motivation, anxiety, and mastery of strategies. Participants were 129 English learners in a comprehensive university in China. Participants read two English texts and were given an…

  16. Long-term convergence of speech rhythm in L1 and L2 English

    NARCIS (Netherlands)

    Quené, H; Orr, Rosemary

    2014-01-01

    When talkers from various language backgrounds use L2 English as a lingua franca, their accents of English are expected to converge, and talkers’ rhythmical patterns are predicted to converge too. Prosodic convergence was studied among talkers who lived in a community where L2 English is used predom

  17. Becoming 'American-Italian": An Immigrant's Narrative of Acquiring English as an L2

    Science.gov (United States)

    Amicucci, Ann N.

    2012-01-01

    This article tells the story of a child immigrant's L2 acquisition process. The narrative demonstrates the effects of social and academic factors on motivation to acquire an L2 and the result of immigration at a young age on cultural identity formation. The article begins by discussing the need for research into sociocultural factors in the second…

  18. The Role of L1 Literacy on L2 Literacy Learning

    Institute of Scientific and Technical Information of China (English)

    张洁

    2014-01-01

    A native language can be learned effortlessly, while a second language is always difficult for people to learn. L1 literacy may impede or promote L2 literacy learning. This paper discusses the role L1 Literacy on L2 Literacy Learning.

  19. L2/FL Teacher Education: Bridging the complexities of Teaching and the Learning of Teaching

    Directory of Open Access Journals (Sweden)

    Karen E. Johnson

    2015-06-01

    Full Text Available http://dx.doi.org/10.5007/2175-8026.2015v68n1p11 Research on approaches to and the complexities of second and foreign language (L2/FL teaching has dominated the field of L2/FL teacher education for much of its history. (...

  20. Crystal Structures of Intermediates in the Dehalogenation of Haloalkanoates by L-2-Haloacid Dehalogenase

    NARCIS (Netherlands)

    Ridder, Ivo S.; Rozeboom, Henriëtte J.; Kalk, Kor H.; Dijkstra, Bauke W.

    1999-01-01

    The L-2-haloacid dehalogenase from the 1,2-dichloroethane-degrading bacterium Xanthobacter autotrophicus GJ10 catalyzes the hydrolytic dehalogenation of small L-2-haloalkanoates to their corresponding D-2-hydroxyalkanoates, with inversion of the configuration at the C2 atom. The structure of the

  1. Applying Cognitive Linguistics to Instructed L2 Learning: The English Modals

    Science.gov (United States)

    Tyler, Andrea; Mueller, Charles M.; Ho, Vu

    2010-01-01

    This paper reports the results of a quasi-experimental effects-of-instruction study examining the efficacy of applying a Cognitive Linguistic (CL) approach to L2 learning of the semantics of English modals. In spite of their frequency in typical input, modal verbs present L2 learners with difficulties, party due to their inherent…

  2. Unconventional Expressions: Productive Syntax in the L2 Acquisition of Formulaic Language

    Science.gov (United States)

    Bardovi-Harlig, Kathleen; Stringer, David

    2017-01-01

    This article presents a generative analysis of the acquisition of formulaic language as an alternative to current usage-based proposals. One influential view of the role of formulaic expressions in second language (L2) development is that they are a bootstrapping mechanism into the L2 grammar; an initial repertoire of constructions allows for…

  3. L2-Proficiency-Dependent Laterality Shift in Structural Connectivity of Brain Language Pathways

    NARCIS (Netherlands)

    Xiang, H.; Leeuwen, T.M. van; Dediu, D.; Roberts, L.; Norris, D.G.; Hagoort, P.

    2015-01-01

    Diffusion tensor imaging (DTI) and a longitudinal language learning approach were applied to investigate the relationship between the achieved second language (L2) proficiency during L2 learning and the reorganization of structural connectivity between core language areas. Language proficiency tests

  4. L2-proficiency-dependent laterality shift in structural connectivity of brain language pathways

    NARCIS (Netherlands)

    Xiang, H.; Leeuwen, T.M. van; Dediu, D.; Roberts, L.; Norris, D.G.; Hagoort, P.

    2015-01-01

    Diffusion tensor imaging (DTI) and a longitudinal language learning approach were applied to investigate the relationship between the achieved second language (L2) proficiency during L2 learning and the reorganization of structural connectivity between core language areas. Language proficiency tests

  5. From Seeing Adverbs to Seeing Verbal Morphology: Language Experience and Adult Acquisition of L2 Tense

    Science.gov (United States)

    Sagarra, Nuria; Ellis, Nick C.

    2013-01-01

    Adult learners have persistent difficulty processing second language (L2) inflectional morphology. We investigate associative learning explanations that involve the blocking of later experienced cues by earlier learned ones in the first language (L1; i.e., transfer) and the L2 (i.e., proficiency). Sagarra (2008) and Ellis and Sagarra (2010b) found…

  6. L1 and L2 Distance Effects in Learning L3 Dutch

    Science.gov (United States)

    Schepens, Job J.; der Slik, Frans; Hout, Roeland

    2016-01-01

    Many people speak more than two languages. How do languages acquired earlier affect the learnability of additional languages? We show that linguistic distances between speakers' first (L1) and second (L2) languages and their third (L3) language play a role. Larger distances from the L1 to the L3 and from the L2 to the L3 correlate with lower…

  7. College Students' Possible L2 Self Development in an EFL Context during the Transition Year

    Science.gov (United States)

    Zhan, Ying; Wan, Zhi Hong

    2016-01-01

    In the field of second language learning motivation, the studies on process-oriented nature of possible L2 selves are scarce. In order to address this research gap, this study explored how a group of five Chinese non-English-major undergraduates developed their possible L2 selves during the transition year from high school to university. The…

  8. Concurrent Data Elicitation Procedures, Processes, and the Early Stages of L2 Learning: A Critical Overview

    Science.gov (United States)

    Leow, Ronald P.; Grey, Sarah; Marijuan, Silvia; Moorman, Colleen

    2014-01-01

    Given the current methodological interest in eliciting direct data on the cognitive processes L2 learners employ as they interact with L2 data during the early stages of the learning process, this article takes a critical and comparative look at three concurrent data elicitation procedures currently employed in the SLA literature: Think aloud (TA)…

  9. Translation assistance by translation of L1 fragments in an L2 context

    NARCIS (Netherlands)

    Gompel, M. van; Bosch, A.P.J. van den

    2014-01-01

    In this paper we present new research in translation assistance. We describe a system capable of translating native language (L1) fragments to foreign language (L2) fragments in an L2 context. Practical applications of this research can be framed in the context of second language learning. The type

  10. Corrective Feedback in L2 Latvian Classrooms: Teacher Perceptions versus the Observed Actualities of Practice

    Science.gov (United States)

    Dilans, Gatis

    2016-01-01

    This two-part study aims to investigate teacher perceptions about providing oral corrective feedback (CF) to minority students of Latvian as a second language and compare the perceptions to the actual provision of CF in L2 Latvian classrooms. The survey sample represents sixty-six L2 Latvian teachers while the classroom observations involved 13…

  11. The Interaction of Instruction and Learner-Internal Factors in the Acquisition of L2 Morphosyntax.

    Science.gov (United States)

    Toth, Paul D.

    2000-01-01

    Considers the role of instruction, second language (L2) input, first language (L1) transfer, and universal grammar in development of L2 morphosyntactic knowledge. Specifically investigates the acquisition of the Spanish morpheme "se" by English-speaking adult learners. (Author/VWL)

  12. Construction of a Rated Speech Corpus of L2 Learners' Spontaneous Speech

    Science.gov (United States)

    Yoon, Su-Youn; Pierce, Lisa; Huensch, Amanda; Juul, Eric; Perkins, Samantha; Sproat, Richard; Hasegawa-Johnson, Mark

    2009-01-01

    This work reports on the construction of a rated database of spontaneous speech produced by second language (L2) learners of English. Spontaneous speech was collected from 28 L2 speakers representing six language backgrounds and five different proficiency levels. Speech was elicited using formats similar to that of the TOEFL iBT and the Speaking…

  13. Investigating the Pedagogical Potential of Recasts for L2 Vowel Acquisition

    Science.gov (United States)

    Saito, Kazuya; Lyster, Roy

    2012-01-01

    Whereas second language (L2) education research has extensively examined how different types of interactional feedback can be facilitative of L2 development in meaning-oriented classrooms, most of these primary studies have focused on recasts (i.e., teachers' reformulations of students' errors). Some researchers have claimed that recasts serve an…

  14. Older Learners in SLA Research: A First Look at Working Memory, Feedback, and L2 Development

    Science.gov (United States)

    Mackey, Alison; Sachs, Rebecca

    2012-01-01

    A great deal of research into second-language (L2) development focuses on the role of cognitive factors and other individual differences. Studies of children and prime-of-life adult L2 learners suggest that differences exist in the learning processes of these groups. However, to date, little empirical work has been conducted with older adult…

  15. Developmental Trends and L1 Effects in Early L2 Learners' Onset Cluster Production

    Science.gov (United States)

    Tessier, Anne-Michelle; Duncan, Tamara Sorenson; Paradis, Johanne

    2013-01-01

    This study focuses on English onset cluster production in spontaneous speech samples of 10 children aged 5;04-6;09 from Chinese and Hindi/Punjabi first language (L1) backgrounds, each with less than a year of exposure to English. The results suggest commonalities between early second language (L2) learners and both monolingual and adult L2

  16. Cognitive Factors Contributing to Chinese EFL Learners' L2 Writing Performance in Timed Essay Writing

    Science.gov (United States)

    Lu, Yanbin

    2010-01-01

    This study investigated cognitive factors that might influence Chinese EFL learners' argumentative essay writing in English. The factors that were explored included English (L2) language proficiency, Chinese (L1) writing ability, genre knowledge, use of writing strategies, and working memory capacity in L1 and L2. Data were collected from 136…

  17. Listening in a Multilingual World: The Challenges of Second Language (L2) Listening

    Science.gov (United States)

    Rost, Michael

    2014-01-01

    Research into language acquisition and oral language use was examined in order to identify key factors that contribute to the successful acquisition of second language (L2) listening ability. The factors were grouped into three major domains: affective, cognitive, and interpersonal. It is claimed that in each domain, proficient L2 listeners have…

  18. Perceptions of the Difficulties of Postgraduate L2 Thesis Students Writing the Discussion Section

    Science.gov (United States)

    Bitchener, John; Basturkmen, Helen

    2006-01-01

    In postgraduate study, students including L2 students are often required to write a thesis and, as a growing literature reveals, L2 students often experience difficulties in the writing of this genre. While most of this research has involved surveys (questionnaires and interviews) and case studies of supervisor perceptions, only a few studies have…

  19. Writing in an Electronic Age: A Case Study of L2 Composing Processes

    Science.gov (United States)

    Stapleton, Paul

    2010-01-01

    Studies on second language (L2) learners writing in English have found that composing is a recursive process requiring planning, formulating and revising. Of particular note among the many studies that have explored the composing processes of L2 writers are two characteristics: 1) They examine the composing processes of writers in real-time while…

  20. Descriptive and Criterion-Referenced Self-Assessment with L2 Readers

    Science.gov (United States)

    Brantmeier, Cindy; Vanderplank, Robert

    2008-01-01

    Brantmeier [Brantmeier, C., 2006. "Advanced L2 learners and reading placement: self-assessment, computer-based testing, and subsequent performance." 'System 34" (1), 15-35] found that self-assessment (SA) of second language (L2) reading ability is not an accurate predictor for computer-based testing or subsequent classroom performance. With 359…

  1. Convergence and Divergence of Process and Portfolio Approaches to L2 Writing Instruction: Issues and Implications

    Science.gov (United States)

    Lam, Ricky

    2015-01-01

    In the L2 writing literature, there has been a rich history of scholarship in theory, research and practice since the 1960s. Two of the most prominent L2 writing approaches are process and portfolio pedagogy. The former approach promotes the use of diverse writing strategies (e.g. pre-writing) to enhance student writers' expression and fluency.…

  2. Convergence and Divergence of Process and Portfolio Approaches to L2 Writing Instruction: Issues and Implications

    Science.gov (United States)

    Lam, Ricky

    2015-01-01

    In the L2 writing literature, there has been a rich history of scholarship in theory, research and practice since the 1960s. Two of the most prominent L2 writing approaches are process and portfolio pedagogy. The former approach promotes the use of diverse writing strategies (e.g. pre-writing) to enhance student writers' expression and fluency.…

  3. Acquisition of L2 Vowel Duration in Japanese by Native English Speakers

    Science.gov (United States)

    Okuno, Tomoko

    2013-01-01

    Research has demonstrated that focused perceptual training facilitates L2 learners' segmental perception and spoken word identification. Hardison (2003) and Motohashi-Saigo and Hardison (2009) found benefits of visual cues in the training for acquisition of L2 contrasts. The present study examined factors affecting perception and production…

  4. Perceptual Paths to Accurate Production of L2 Vowels: The Role of Individual Differences

    Science.gov (United States)

    Baker, Wendy; Trofimovich, Pavel

    2006-01-01

    This study investigated whether individual differences in learners' age of arrival (AOA) and length of residence (LOR) in a country where a second language (L2) is spoken determine the relationship between L2 perception and production. In the first experiment, 40 Korean learners of English and 10 native English speakers participated in vowel…

  5. The Roles of First Language and Proficiency in L2 Processing of Spanish Clitics: Global Effects

    Science.gov (United States)

    Seibert Hanson, Aroline E.; Carlson, Matthew T.

    2014-01-01

    We assessed the roles of first language (L1) and second language (L2) proficiency in the processing of preverbal clitics in L2 Spanish by considering the predictions of four processing theories--the Input Processing Theory, the Unified Competition Model, the Amalgamation Model, and the Associative-Cognitive CREED. We compared the performance of L1…

  6. Effects of Varying Text Difficulty Levels on Second Language (L2) Reading Attitudes and Reading Comprehension

    Science.gov (United States)

    Chiang, Min-Hsun

    2016-01-01

    This study investigated the effects of varying text difficulty on L2 reading attitudes and reading comprehension. To provide the optimal challenge for L2 reading, comprehensible input hypothesis postulates that choosing text slightly harder than the learner's current level will enhance reading comprehension. Fifty-four freshmen from one university…

  7. L2 and L3 Ultimate Attainment: An Investigation of Two Parameters

    Science.gov (United States)

    Hermas, Abdelkader

    2014-01-01

    This study considers the upper limit of ultimate attainment in the L2 French and L3 English of trilingual learners. The learners are native speakers of Moroccan Arabic who started learning L2 French at eight and L3 English at 16. They are advanced in both languages. Four constructions representing the verb movement and null subject parameter were…

  8. L2 Reading Comprehension and Its Correlates: A Meta-Analysis

    Science.gov (United States)

    Jeon, Eun Hee; Yamashita, Junko

    2014-01-01

    The present meta-analysis examined the overall average correlation (weighted for sample size and corrected for measurement error) between passage-level second language (L2) reading comprehension and 10 key reading component variables investigated in the research domain. Four high-evidence correlates (with 18 or more accumulated effect sizes: L2

  9. The production and processing of determiner-noun agreement in child L2 Dutch

    NARCIS (Netherlands)

    Blom, E.; Vasić, N.

    2011-01-01

    Recent research has shown that children who learn Dutch as their second language (L2) have difficulties with Dutch grammatical gender. This study shows that six to nine year old L2 Dutch children whose first language (L1) is Turkish noticed incorrect gender agreement between determiner and noun only

  10. Language Interference and Language Learning Techniques Transfer in L2 and L3 Immersion Programs.

    Science.gov (United States)

    Aronin, Larissa; Toubkin, Lynne

    2002-01-01

    Examines the relationships between the first (L1), second (L2), and third (L3) language in immersion programs for Russian-speaking students in Israel. Two parallel and similar immersion programs, which were carried out for the same population, but with different target languages (L2 Hebrew and L3 English), are described. Presents tentative…

  11. Factors Affecting Grammatical and Lexical Complexity of Long-Term L2 Speakers’ Oral Proficiency

    NARCIS (Netherlands)

    Lahmann, Cornelia; Steinkrauss, Rasmus; Schmid, Monika

    2016-01-01

    There remains considerable disagreement about which factors drive second language (L2) ultimate attainment. Age of onset (AO) appears to be a robust factor, lending support to theories of maturational constraints on L2 acquisition. The present study is an investigation of factors that influence gram

  12. Early Child L2 Acquisition: Age or Input Effects? Neither, or Both?

    Science.gov (United States)

    Unsworth, Sharon

    2016-01-01

    This paper explores whether there is evidence for age and/or input effects in child L2 acquisition across three different linguistic domains, namely morphosyntax, vocabulary, and syntax-semantics. More specifically, it compares data from English-speaking children whose age of onset to L2 Dutch was between one and three years with data from…

  13. Effects of Web-Based Collaborative Writing on Individual L2 Writing Development

    Science.gov (United States)

    Bikowski, Dawn; Vithanage, Ramyadarshanie

    2016-01-01

    This study investigated the effect of repeated in-class web-based collaborative writing tasks on second language writers' (L2) individual writing scores. A pre-test post-test research model was used in addition to participant surveys, class observations, and teacher interviews. Participants included 59 L2 writers in a writing class at a large U.S.…

  14. NFE2L2 polymorphisms, mortality, and metabolism in the general population

    NARCIS (Netherlands)

    Figarska, Sylwia M.; Vonk, Judith M.; Boezen, Hendrika

    2014-01-01

    The nuclear factor (erythroid-derived 2)-like 2 (NFE2L2 or NRF2) gene regulates transcription of enzymes involved in cellular detoxification and lipids homeostasis. NFE2L2 is associated with pathophysiology of atherosclerosis and chronic obstructive pulmonary disease (COPD). Therefore we studied the

  15. The vulnerability of gender on determiners in L1, 2L1 and L2 acquisition

    NARCIS (Netherlands)

    van der Linden, E.; Hulk, A.

    2009-01-01

    The acquisition of gender has been reported to be problematic for some groups of learners acquiring Germanic or Romance languages. It has been shown that L1 learners do better in gender acquisition than others, like bilingual children, child L2 learners and adult L2 learners. The reason for these di

  16. From Number Agreement to the Subjunctive: Evidence for Processability Theory in L2 Spanish

    Science.gov (United States)

    Bonilla, Carrie L.

    2015-01-01

    This article contributes to typological plausibility of Processability Theory (PT) (Pienemann, 1998, 2005) by providing empirical data that show that the stages predicted by PT are followed in the second language (L2) acquisition of Spanish syntax and morphology. In the present article, the PT stages for L2 Spanish morphology and syntax are first…

  17. Islands and Objects in L2 Spanish: Do You Know the Learners Who Drop___?

    Science.gov (United States)

    Rothman, Jason; Iverson, Michael

    2013-01-01

    This study tests native Brazilian Portuguese (BP) speakers of second language (L2) Spanish in the domain of phonologically null object pronouns. This is a worthwhile first language (L1)-L2 pairing given that these languages are historically and typologically related and both seemingly allow for object drop. Nevertheless, the underlying syntax of…

  18. L1-L2 Convergence in Clausal Packaging in Japanese and English

    Science.gov (United States)

    Brown, Amanda; Gullberg, Marianne

    2013-01-01

    This study investigates L1-L2 convergence among bilinguals at an intermediate (CEFR-B2) level of L2 proficiency, focusing on the clausal packaging of Manner and Path of motion. Previous research has shown cross-linguistic differences between English and Japanese in this domain (Allen et al., 2003; Kita & Ozyurek, 2003, though note Brown &…

  19. The vulnerability of gender on determiners in L1, 2L1 and L2 acquisition

    NARCIS (Netherlands)

    van der Linden, E.; Hulk, A.

    2009-01-01

    The acquisition of gender has been reported to be problematic for some groups of learners acquiring Germanic or Romance languages. It has been shown that L1 learners do better in gender acquisition than others, like bilingual children, child L2 learners and adult L2 learners. The reason for these

  20. Cross-Linguistic Variation and the Acquisition of Pronominal Reference in L2 Spanish

    Science.gov (United States)

    Jegerski, Jill; VanPatten, Bill; Keating, Gregory D.

    2011-01-01

    The current investigation tested two predictions regarding second language (L2) processing at the syntax-discourse interface: (1) that L2 performance on measures of interface phenomena can differ from that of native speakers; and (2) that cross-linguistic influence can be a source of such divergence. Specifically, we examined the offline…

  1. Becoming 'American-Italian": An Immigrant's Narrative of Acquiring English as an L2

    Science.gov (United States)

    Amicucci, Ann N.

    2012-01-01

    This article tells the story of a child immigrant's L2 acquisition process. The narrative demonstrates the effects of social and academic factors on motivation to acquire an L2 and the result of immigration at a young age on cultural identity formation. The article begins by discussing the need for research into sociocultural factors in the second…

  2. The Impact of CLIL on L2 Vocabulary Development and Content Knowledge

    Science.gov (United States)

    Xanthou, Maria

    2011-01-01

    This paper examines whether students involved in CLIL are able to learn content through the medium of L2 and simultaneously exhibit significant gains in L2 vocabulary knowledge. Two experiments were set up in two public primary schools. Two groups of 6th grade students participated in each experiment. The first group was taught three 80-minute…

  3. L2 Reading Perceptions of Learners of Japanese: The Influence of the Reading Instruction

    Science.gov (United States)

    Tabata-Sandom, Mitsue

    2015-01-01

    The nature of learning to read in a second and foreign language (L2) can be more challenging when compared to learning other subjects. Therefore, the influence of instruction given in L2 classrooms cannot be underestimated. A balanced instruction needs to be taken in order to develop learners' reading proficiency and their motivation to read. This…

  4. The Effects of Hypertext Glosses on L2 Vocabulary Acquisition: A Meta-Analysis

    Science.gov (United States)

    Yun, Jeehwan

    2011-01-01

    This study examines (1) the effects of hypertext gloss use on L2 vocabulary acquisition in computerized reading contexts; (2) which specific combination of either text-only (single) or text + visual (multiple) hypertext glosses is more effective on L2 vocabulary acquisition; and (3) potential moderators to systematically account for between study…

  5. Mediation Strategies in L2 Writing Processes: A Case Study of Two Korean Language Learners

    Science.gov (United States)

    Kang, Yon-Soo; Pyun, Danielle Ooyoung

    2013-01-01

    With the recent rise of sociocultural theory in second-language acquisition, attempts have been made to understand L2 learners' uses of different resources in writing, based on their cultural, historical, and institutional contexts. In line with L2 writing research within the sociocultural paradigm, this study investigates the writing strategies…

  6. L2 Decay for Weak Solutions of the Boussinesq Equations%Boussinesq方程组弱解的L2衰减

    Institute of Scientific and Technical Information of China (English)

    刘颖; 李军; 杜健; 詹环

    2012-01-01

    利用付立叶分解方法(Fourier splitting method)研究Boussinesq方程组Cauchy问题弱解的L2衰减.%We first get the uniform L2 decay of the smooth solutions. Then we can actually obtain the L2 decay for weak solutions by passing limit of the approximate sequences of solutions. The main tool used is the Fourier splitting method. We first consider the large-time behavior of the temperature of the Boussinesq equations,based on which we can obtain,under some assumption of the decay rate of given f,the large time behavior of the velocity vector field.

  7. A mouse model of L-2-hydroxyglutaric aciduria, a disorder of metabolite repair.

    Directory of Open Access Journals (Sweden)

    Rim Rzem

    Full Text Available The purpose of the present work was to progress in our understanding of the pathophysiology of L-2-hydroxyglutaric aciduria, due to a defect in L-2-hydroxyglutarate dehydrogenase, by creating and studying a mouse model of this disease. L-2-hydroxyglutarate dehydrogenase-deficient mice (l2hgdh-/- accumulated L-2-hydroxyglutarate in tissues, most particularly in brain and testis, where the concentration reached ≈ 3.5 μmol/g. Male mice showed a 30% higher excretion of L-2-hydroxyglutarate compared to female mice, supporting that this dicarboxylic acid is partially made in males by lactate dehydrogenase C, a poorly specific form of this enzyme exclusively expressed in testes. Involvement of mitochondrial malate dehydrogenase in the formation of L-2-hydroxyglutarate was supported by the commensurate decrease in the formation of this dicarboxylic acid when down-regulating this enzyme in mouse l2hgdh-/- embryonic fibroblasts. The concentration of lysine and arginine was markedly increased in the brain of l2hgdh-/- adult mice. Saccharopine was depleted and glutamine was decreased by ≈ 40%. Lysine-α-ketoglutarate reductase, which converts lysine to saccharopine, was inhibited by L-2-hydroxyglutarate with a Ki of ≈ 0.8 mM. As low but significant activities of the bifunctional enzyme lysine-α-ketoglutarate reductase/saccharopine dehydrogenase were found in brain, these findings suggest that the classical lysine degradation pathway also operates in brain and is inhibited by the high concentrations of L-2-hydroxyglutarate found in l2hgdh-/- mice. Pathological analysis of the brain showed significant spongiosis. The vacuolar lesions mostly affected oligodendrocytes and myelin sheats, as in other dicarboxylic acidurias, suggesting that the pathophysiology of this model of leukodystrophy may involve irreversible pumping of a dicarboxylate in oligodendrocytes. Neurobehavioral testing indicated that the mice mostly suffered from a deficit in learning

  8. Language aptitude for pronunciation in advanced second language (L2) learners: behavioural predictors and neural substrates.

    Science.gov (United States)

    Hu, Xiaochen; Ackermann, Hermann; Martin, Jason A; Erb, Michael; Winkler, Susanne; Reiterer, Susanne M

    2013-12-01

    Individual differences in second language (L2) aptitude have been assumed to depend upon a variety of cognitive and personality factors. Especially, the cognitive factor phonological working memory has been conceptualised as language learning device. However, strong associations between phonological working memory and L2 aptitude have been previously found in early-stage learners only, not in advanced learners. The current study aimed at investigating the behavioural and neurobiological predictors of advanced L2 learning. Our behavioural results showed that phonetic coding ability and empathy, but not phonological working memory, predict L2 pronunciation aptitude in advanced learners. Second, functional neuroimaging revealed this behavioural trait to be correlated with hemodynamic responses of the cerebral network of speech motor control and auditory-perceptual areas. We suggest that the acquisition of L2 pronunciation aptitude is a dynamic process, requiring a variety of neural resources at different processing stages over time. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. L1+L2正则化逻辑斯蒂模型分类算法%Logistic Model Classification Algorithm via L1+L2 Regularization

    Institute of Scientific and Technical Information of China (English)

    刘建伟; 付捷; 罗雄麟

    2012-01-01

    提出一种L1+L2范数正则化逻辑斯蒂模型分类算法.该算法引入L2范数正则化,解决L1正则化逻辑斯蒂算法迭代过程奇异问题,通过引入样本向量的扩展和新的权值向量完成L1范数非平滑问题,最终使用共轭梯度方法求解经过转化的最优化问题.在各种实际数据集上的实验结果表明,该算法优于L2范数、L1范数和Lp范数正则化逻辑斯蒂模型,具有较好的特征选择和分类性能.%This paper proposes an L1+L2 norm regularized logistic model classification algorithm, and the singularity of iterative process in LI norm regularized logistic classification algorithm is solved by using L2 norm regularization. The non-smooth problem is transformed into smooth one via argumentation of vector of samples and introduction of new weight vector, and classification object function is solved using the conjugate gradient method. Performance of classification and feature selection on real datasets shows that the algorithm is better than L2 norm, LI nrom and Lp norm regularized logistic model.

  10. Nucleic localization of human papillomavirus minor capsid protein L2%人乳头瘤病毒次要衣壳蛋白L2核定位

    Institute of Scientific and Technical Information of China (English)

    陈卫东; 井申荣

    2012-01-01

    在人乳头瘤病毒(human papillomavirus,HPV)次要衣壳蛋白L2的N端和C端,有大量带正电荷的氨基酸残基组成核定位信号(nuclear localization signal,NLS).细胞的核结构域10 (nuclear domain 10,ND10)是细胞周期和病毒生活周期的重要调节者.L2定位到ND10的过程不仅会受到早幼粒细胞白血病蛋白(promyleocytic leukaemia protein,PML)、死亡结构域相关蛋白(death domain-associated protein,Daxx)、Sp100核抗原(Sp100 nuclear antigen)等细胞蛋白的影响,也会与L1在ND10发生相互作用.在HPV感染和组装过程中,L2的核定位信号有着重要作用.%The nuclear localization signal, NLS, which is composed of many amino acids with positive charge residue, is located in both ends of N terminus and C terminus of the human papillomavirus minor capsid protein L2. The nuclear domain 10, ND-10, which is in the cell nucleus, is an important modulator of both cell cycle and virus cyclogeny. The process of the locating of L2 to ND-10, is not only impacted by the cell proteins, such as the promyelocytic leukemia protein, death domain-associated protein Daxx, nuclear antigen Sp100, but also interacts with L1 in ND-10. The NLS of L2 plays a significant role during the HPV virus assembly course.

  11. The L(2,1)-labeling Problem on Several Classes of Graphs%关于几类图的L(2,1)标号问题

    Institute of Scientific and Technical Information of China (English)

    邵振东; 刘家壮

    2004-01-01

    An L(2,1) labeling of a graph G is a function f from the vertex set V(G) to the set of all nonnegative integers such that | f(x) - f(y)|≥ 2 ifd(x,y) = 1 and |f(x) - f(y) |≥ 1 if d(x,y) = 2. The L(2,1)- labeling number λ(G) of G is the smallest number k such that G has an L(2,1)-labeling with max{ f(v): v ∈ V(G)) = k. Griggs and Yeh conjecture thatλ(G) ≤△2 for any simple graph with maximum degree△. In this paper, we derive the upper bounds of λ(G) of Kneser graph,Mycielski graph,Descartes graph, Halin graph, and prove that the conjecture is true for the above several classes of graphs.%图G的L(2,1)标号是一个从顶点集V(G)到非负整数集的函数f(x),使得若d(x,y)=1,则 |f(x)-f(y)|≥2;若d(x,y)=2,则 |f(x)-f(y)|≥1.图G的L(2,1)-标号数λ(G)是使得G有max{f(v):v∈V(G)}=k的L(2,1)标号中的最小数k.Griggs和Yeh猜想对最大度为△的一般图G,有λ(G)≤△2.本文给出了Kneser图,Mycieklski图,Descartes图,Halin图的λ值的上界,并证明了上述猜想对以上几类图成立.

  12. L2-Trigger Time Study Based on Motion Prediction%基于运动预测的L2-Trigger触发时机研究

    Institute of Scientific and Technical Information of China (English)

    姚胜; 唐宏

    2011-01-01

    针对Ad hoc网络存在的切换问题,有文献提出L2-Trigger方法提前触发三层切换从而降低切换时延,但触发时机不明确.本文介绍了切换的基本流程,提出了基于运动预测的方法.通过引入移动模型并对L2-Trigger的触发时机进行仿真和分析,说明了该方法的简单和可行性.

  13. VLPs displaying a single L2 epitope induce broadly cross-neutralizing antibodies against human papillomavirus.

    Directory of Open Access Journals (Sweden)

    Ebenezer Tumban

    Full Text Available BACKGROUND: Virus-like Particles (VLPs display can be used to increase the immunogenicity of heterologous antigens. Here, we report the use of a bacteriophage MS2-based VLP display platform to develop a monovalent vaccine targeting a broadly neutralizing epitope in the minor capsid protein human papillomavirus (HPV that provides broad protection from diverse HPV types in a mouse pseudovirus infection model. METHODOLOGY/PRINCIPAL FINDINGS: Peptides spanning a previously described cross-neutralizing epitope from HPV type 16 were genetically inserted at the N-terminus of MS2 bacteriophage coat protein. Three of the four recombinant L2-coat proteins assembled into VLPs. L2-VLPs elicited high-titer anti-L2 antibodies in mice, similar to recombinant VLPs that we had previously made in which the L2 peptide was displayed on a surface-exposed loop on VLPs of a related bacteriophage, PP7. Somewhat surprisingly, L2-MS2 VLPs elicited antibodies that were much more broadly cross-reactive with L2 peptides from diverse HPV isolates than L2-PP7 VLPs. Similarly, mice immunized with L2-MS2 VLPs were protected from genital and cutaneous infection by highly diverse HPV pseudovirus types. CONCLUSION/SIGNIFICANCE: We show that peptides can be displayed in a highly immunogenic fashion at the N-terminus of MS2 coat protein VLPs. A VLP-based vaccine targeting HPV L2 elicits broadly cross-reactive and cross-protective antibodies to heterologous HPV types. L2-VLPs could serve as the basis of a broadly protective second generation HPV vaccine.

  14. TCF7L2 Regulates Late Events in Insulin Secretion From Pancreatic Islet β-Cells

    Science.gov (United States)

    da Silva Xavier, Gabriela; Loder, Merewyn K.; McDonald, Angela; Tarasov, Andrei I.; Carzaniga, Raffaella; Kronenberger, Katrin; Barg, Sebastian; Rutter, Guy A.

    2009-01-01

    OBJECTIVE Polymorphisms in the human TCF7L2 gene are associated with reduced insulin secretion and an increased risk of type 2 diabetes. However, the mechanisms by which TCF7L2 affect insulin secretion are still unclear. We define the effects of TCF7L2 expression level on mature β-cell function and suggest a potential mechanism for its actions. RESEARCH DESIGN AND METHODS TCF7L2 expression in rodent islets and β-cell lines was altered using RNAi or adenoviral transduction. β-Cell gene profiles were measured by quantitative real-time PCR and the effects on intracellular signaling and exocytosis by live cell imaging, electron microscopy, and patch clamp electrophysiology. RESULTS Reducing TCF7L2 expression levels by RNAi decreased glucose- but not KCl-induced insulin secretion. The glucose-induced increments in both ATP/ADP ratio and cytosolic free Ca2+ concentration ([Ca2+]i) were increased compared with controls. Overexpression of TCF7L2 exerted minor inhibitory effects on glucose-regulated changes in [Ca2+]i and insulin release. Gene expression profiling in TCF7L2-silenced cells revealed increased levels of mRNA encoding syntaxin 1A but decreased Munc18–1 and ZnT8 mRNA. Whereas the number of morphologically docked vesicles was unchanged by TCF7L2 suppression, secretory granule movement increased and capacitance changes decreased, indicative of defective vesicle fusion. CONCLUSION—TCF7L2 is involved in maintaining expression of β-cell genes regulating secretory granule fusion. Defective insulin exocytosis may thus underlie increased diabetes incidence in carriers of the at-risk TCF7L2 alleles. PMID:19168596

  15. TCF7L2 regulates late events in insulin secretion from pancreatic islet beta-cells.

    Science.gov (United States)

    da Silva Xavier, Gabriela; Loder, Merewyn K; McDonald, Angela; Tarasov, Andrei I; Carzaniga, Raffaella; Kronenberger, Katrin; Barg, Sebastian; Rutter, Guy A

    2009-04-01

    Polymorphisms in the human TCF7L2 gene are associated with reduced insulin secretion and an increased risk of type 2 diabetes. However, the mechanisms by which TCF7L2 affect insulin secretion are still unclear. We define the effects of TCF7L2 expression level on mature beta-cell function and suggest a potential mechanism for its actions. TCF7L2 expression in rodent islets and beta-cell lines was altered using RNAi or adenoviral transduction. Beta-cell gene profiles were measured by quantitative real-time PCR and the effects on intracellular signaling and exocytosis by live cell imaging, electron microscopy, and patch clamp electrophysiology. Reducing TCF7L2 expression levels by RNAi decreased glucose- but not KCl-induced insulin secretion. The glucose-induced increments in both ATP/ADP ratio and cytosolic free Ca2+ concentration ([Ca2+]i) were increased compared with controls. Overexpression of TCF7L2 exerted minor inhibitory effects on glucose-regulated changes in [Ca2+]i and insulin release. Gene expression profiling in TCF7L2-silenced cells revealed increased levels of mRNA encoding syntaxin 1A but decreased Munc18-1 and ZnT8 mRNA. Whereas the number of morphologically docked vesicles was unchanged by TCF7L2 suppression, secretory granule movement increased and capacitance changes decreased, indicative of defective vesicle fusion. TCF7L2 is involved in maintaining expression of beta-cell genes regulating secretory granule fusion. Defective insulin exocytosis may thus underlie increased diabetes incidence in carriers of the at-risk TCF7L2 alleles.

  16. Topography of the Human Papillomavirus Minor Capsid Protein L2 during Vesicular Trafficking of Infectious Entry

    Science.gov (United States)

    DiGiuseppe, Stephen; Keiffer, Timothy R.; Bienkowska-Haba, Malgorzata; Luszczek, Wioleta; Guion, Lucile G. M.; Müller, Martin

    2015-01-01

    ABSTRACT The human papillomavirus (HPV) capsid is composed of the major capsid protein L1 and the minor capsid protein L2. During entry, the HPV capsid undergoes numerous conformational changes that result in endosomal uptake and subsequent trafficking of the L2 protein in complex with the viral DNA to the trans-Golgi network. To facilitate this transport, the L2 protein harbors a number of putative motifs that, if capable of direct interaction, would interact with cytosolic host cell factors. These data imply that a portion of L2 becomes cytosolic during infection. Using a low concentration of digitonin to selectively permeabilize the plasma membrane of infected cells, we mapped the topography of the L2 protein during infection. We observed that epitopes within amino acid residues 64 to 81 and 163 to 170 and a C-terminal tag of HPV16 L2 are exposed on the cytosolic side of intracellular membranes, whereas an epitope within residues 20 to 38, which are upstream of a putative transmembrane region, is luminal. Corroborating these findings, we also found that L2 protein is sensitive to trypsin digestion during infection. These data demonstrate that the majority of the L2 protein becomes accessible on the cytosolic side of intracellular membranes in order to interact with cytosolic factors to facilitate vesicular trafficking. IMPORTANCE In order to complete infectious entry, nonenveloped viruses have to pass cellular membranes. This is often achieved through the viral capsid protein associating with or integrating into intracellular membrane. Here, we determine the topography of HPV L2 protein in the endocytic vesicular compartment, suggesting that L2 becomes a transmembrane protein with a short luminal portion and with the majority facing the cytosolic side for interaction with host cell transport factors. PMID:26246568

  17. Approximation of Quantities of Interest in Stochastic PDEs by the Random Discrete L^2 Projection on Polynomial Spaces

    KAUST Repository

    Migliorati, G.

    2013-05-30

    In this work we consider the random discrete L^2 projection on polynomial spaces (hereafter RDP) for the approximation of scalar quantities of interest (QOIs) related to the solution of a partial differential equation model with random input parameters. In the RDP technique the QOI is first computed for independent samples of the random input parameters, as in a standard Monte Carlo approach, and then the QOI is approximated by a multivariate polynomial function of the input parameters using a discrete least squares approach. We consider several examples including the Darcy equations with random permeability, the linear elasticity equations with random elastic coefficient, and the Navier--Stokes equations in random geometries and with random fluid viscosity. We show that the RDP technique is well suited to QOIs that depend smoothly on a moderate number of random parameters. Our numerical tests confirm the theoretical findings in [G. Migliorati, F. Nobile, E. von Schwerin, and R. Tempone, Analysis of the Discrete $L^2$ Projection on Polynomial Spaces with Random Evaluations, MOX report 46-2011, Politecnico di Milano, Milano, Italy, submitted], which have shown that, in the case of a single uniformly distributed random parameter, the RDP technique is stable and optimally convergent if the number of sampling points is proportional to the square of the dimension of the polynomial space. Here optimality means that the weighted $L^2$ norm of the RDP error is bounded from above by the best $L^\\\\infty$ error achievable in the given polynomial space, up to logarithmic factors. In the case of several random input parameters, the numerical evidence indicates that the condition on quadratic growth of the number of sampling points could be relaxed to a linear growth and still achieve stable and optimal convergence. This makes the RDP technique very promising for moderately high dimensional uncertainty quantification.

  18. Tipping Point

    Medline Plus

    Full Text Available ... OnSafety CPSC Stands for Safety The Tipping Point Home > 60 Seconds of Safety (Videos) > The Tipping Point ... 24 hours a day. For young children whose home is a playground, it’s the best way to ...

  19. Nonnativeness in Near-Native Child L2 Starters of Japanese: Age and the Acquisition of Relative Clauses

    Science.gov (United States)

    Nishikawa, Tomomi

    2014-01-01

    Many age-related second language (L2) studies have confirmed that young children have a better chance to become nativelike in L2 acquisition than adults. The current study investigated whether age effects exist in the L2 acquisition of Japanese and whether nativelike proficiency is guaranteed for early child L2 starters after constant target…

  20. An Attempt towards Learner Autonomy in L2 (English) an L3 (Arabic) Reading through Cognitive and Metacognitive Reading Strategy Instruction (CMRSI) in L2

    Science.gov (United States)

    Talebi, Seyed Hassan

    2009-01-01

    This experimental study was intended to raise learner autonomy among Iranian native speakers of Persian in their L2 (English) and L3 (Arabic) reading comprehension through cognitive and metacognitive reading strategies instruction (CMRSI). The subjects of the study were divided into intermediate and advanced English language proficiency levels and…

  1. Processing Subject-Object Ambiguities in the L2: A Self-Paced Reading Study With German L2 Learners of Dutch

    NARCIS (Netherlands)

    Havik, E.M.; Roberts, L.; Hout, R.W.N.M. van; Schreuder, R.; Haverkort, M.

    2009-01-01

    The results of two self-paced reading experiments are reported, which investigated the online processing of subject-object ambiguities in Dutch relative clause constructions like Dat is de vrouw die de meisjes heeft/hebben gezien by German advanced second language (L2) learners of Dutch. Native spea

  2. How new L2 words (don't) become memories : Lexicalization in advanced L1 Dutch learners of L2 English as part of a longitudinal study

    NARCIS (Netherlands)

    Keijzer, Merel

    2016-01-01

    It is an undisputed fact that learning – and remembering – new words is key in successful second language acquisition. And yet researching how vocabulary acquisition takes place is one of the most difficult endeavors in second language acquisition. We can test how many L2 words a learner knows, but

  3. Embodiment and second-language: automatic activation of motor responses during processing spatially associated L2 words and emotion L2 words in a vertical Stroop paradigm.

    Science.gov (United States)

    Dudschig, Carolin; de la Vega, Irmgard; Kaup, Barbara

    2014-05-01

    Converging evidence suggests that understanding our first-language (L1) results in reactivation of experiential sensorimotor traces in the brain. Surprisingly, little is known regarding the involvement of these processes during second-language (L2) processing. Participants saw L1 or L2 words referring to entities with a typical location (e.g., star, mole) (Experiment 1 & 2) or to an emotion (e.g., happy, sad) (Experiment 3). Participants responded to the words' ink color with an upward or downward arm movement. Despite word meaning being fully task-irrelevant, L2 automatically activated motor responses similar to L1 even when L2 was acquired rather late in life (age >11). Specifically, words such as star facilitated upward, and words such as root facilitated downward responses. Additionally, words referring to positive emotions facilitated upward, and words referring to negative emotions facilitated downward responses. In summary our study suggests that reactivation of experiential traces is not limited to L1 processing.

  4. Working Memory Effects on L1 and L2 Processing of Ambiguous Relative Clauses by Korean L2 Learners of English

    Science.gov (United States)

    Kim, Ji Hyon; Christianson, Kiel

    2017-01-01

    In this study, we report the results of two self-paced reading experiments that investigated working memory capacity effects on the processing of globally ambiguous relative clauses by advanced Korean second language (L2) learners of English. Consistent with previous monolingual literature on the processing of temporary ambiguity, we found that…

  5. MPV17L2 is required for ribosome assembly in mitochondria

    Science.gov (United States)

    Dalla Rosa, Ilaria; Durigon, Romina; Pearce, Sarah F.; Rorbach, Joanna; Hirst, Elizabeth M.A.; Vidoni, Sara; Reyes, Aurelio; Brea-Calvo, Gloria; Minczuk, Michal; Woellhaf, Michael W.; Herrmann, Johannes M.; Huynen, Martijn A.; Holt, Ian J.; Spinazzola, Antonella

    2014-01-01

    MPV17 is a mitochondrial protein of unknown function, and mutations in MPV17 are associated with mitochondrial deoxyribonucleic acid (DNA) maintenance disorders. Here we investigated its most similar relative, MPV17L2, which is also annotated as a mitochondrial protein. Mitochondrial fractionation analyses demonstrate MPV17L2 is an integral inner membrane protein, like MPV17. However, unlike MPV17, MPV17L2 is dependent on mitochondrial DNA, as it is absent from ρ0 cells, and co-sediments on sucrose gradients with the large subunit of the mitochondrial ribosome and the monosome. Gene silencing of MPV17L2 results in marked decreases in the monosome and both subunits of the mitochondrial ribosome, leading to impaired protein synthesis in the mitochondria. Depletion of MPV17L2 also induces mitochondrial DNA aggregation. The DNA and ribosome phenotypes are linked, as in the absence of MPV17L2 proteins of the small subunit of the mitochondrial ribosome are trapped in the enlarged nucleoids, in contrast to a component of the large subunit. These findings suggest MPV17L2 contributes to the biogenesis of the mitochondrial ribosome, uniting the two subunits to create the translationally competent monosome, and provide evidence that assembly of the small subunit of the mitochondrial ribosome occurs at the nucleoid. PMID:24948607

  6. Input frequencies in processing of verbal morphology in L1 and L2: Evidence from Russian

    Directory of Open Access Journals (Sweden)

    Tatiana Chernigovskaya

    2011-02-01

    Full Text Available In this study we take a usage-based perspective on the analysis of data from the acquisition of verbal morphology by Norwegian adult learners of L2 Russian, as compared to children acquiring Russian as an L1. According to the usage-based theories, language learning is input-driven and frequency of occurrence of grammatical structures and lexical items in the input plays a key role in this process. We have analysed to what extent the acquisition and processing of Russian verbal morphology by children and adult L2 learners is dependent on the input factors, in particular on type and token frequencies. Our analysis of the L2 input based on the written material used in the instruction shows a different distribution of frequencies as compared to the target language at large. The results of the tests that elicited present tense forms of verbs belonging to four different inflectional classes (-AJ-, -A-, -I-, and -OVA- have demonstrated that for both Russian children and L2 learners type frequency appears to be an important factor, influencing both correct stem recognition and generalisations. The results have also demonstrated token frequency effects. For L2 learners we observed also effects of formal instruction and greater reliance on morphological cues. In spite of the fact that L2 learners did not match completely any of the child groups, there are many similarities between L1 and L2 morphological processing, the main one being the role of frequency.

  7. Tipping Point

    Medline Plus

    Full Text Available ... Point by CPSC Blogger September 22, 2009 appliance child Childproofing CPSC danger death electrical fall furniture head ... see news reports about horrible accidents involving young children and furniture, appliance and tv tip-overs. The ...

  8. How does language distance between L1 and L2 affect the L2 brain network? An fMRI study of Korean-Chinese-English trilinguals.

    Science.gov (United States)

    Kim, Say Young; Qi, Ting; Feng, Xiaoxia; Ding, Guosheng; Liu, Li; Cao, Fan

    2016-04-01

    The present study tested the hypothesis that language distance between first language (L1) and second language (L2) influences the assimilation and accommodation pattern in Korean-Chinese-English trilinguals. The distance between English and Korean is smaller than that between Chinese and Korean in terms of orthographic transparency, because both English and Korean are alphabetic, whereas Chinese is logographic. During fMRI, Korean trilingual participants performed a visual rhyming judgment task in three languages (Korean: KK, Chinese: KC, English: KE). Two L1 control groups were native Chinese and English speakers performing the task in their native languages (CC and EE, respectively). The general pattern of brain activation of KC was more similar to that of CC than KK, suggesting accommodation. Higher accuracy in KC was associated with decreased activation in regions of the KK network, suggesting reduced assimilation. In contrast, the brain activation of KE was more similar to that of KK than EE, suggesting assimilation. Higher accuracy in KE was associated with decreased activation in regions of the EE network, suggesting reduced accommodation. Finally, an ROI analysis on the left middle frontal gyrus revealed greater activation for KC than for KE, suggesting its selective involvement in the L2 with more arbitrary mapping between orthography and phonology (i.e., Chinese). Taken together, the brain network involved in L2 reading is similar to the L1 network when L2 and L1 are similar in orthographic transparency, while significant accommodation is expected when L2 is more opaque than L1. Copyright © 2015. Published by Elsevier Inc.

  9. L^2 Castelnuovo-de Franchis, the cup product lemma, and filtered ends of Kaehler manifolds

    OpenAIRE

    Napier, Terrence; Ramachandran, Mohan

    2007-01-01

    Simple approaches to the proofs of the L^2 Castelnuovo-de Franchis theorem and the cup product lemma which give new versions are developed. For example, suppose u and v are two linearly independent closed holomorphic 1-forms on a bounded geometry connected complete Kaehler manifold X with v in L^2. According to a version of the L^2 Castelnuovo-de Franchis theorem obtained in this paper, if u and v are pointwise linearly dependent, then there exists a surjective proper holomorphic mapping of X...

  10. About radial Toeplitz operators on Segal-Bargmann and $l^2$ spaces

    CERN Document Server

    Ramírez, Romina A; Sanmartino, Marcela

    2010-01-01

    We discuss Toeplitz operators on the Segal-Bargmann space as functional realizations of anti-Wick operators on the Fock space. In the special case of radial symbols we exploit the isometric mapping between the Segal-Bargmann space and $l^2$ complex sequences in order to establish conditions such that an equivalence between Toeplitz operators and diagonal operators on $l^2$ holds. We also analyze the inverse problem of mapping diagonal operators on $l^2$ into Toeplitz form. The composition problem of Toeplitz operators with radial symbols is reviewed as an application. Our notation and basic examples make contact with Quantum Mechanics literature.

  11. Mutations in MAB21L2 result in ocular Coloboma, microcornea and cataracts.

    Directory of Open Access Journals (Sweden)

    Brett Deml

    Full Text Available Ocular coloboma results from abnormal embryonic development and is often associated with additional ocular and systemic features. Coloboma is a highly heterogeneous disorder with many cases remaining unexplained. Whole exome sequencing from two cousins affected with dominant coloboma with microcornea, cataracts, and skeletal dysplasia identified a novel heterozygous allele in MAB21L2, c.151 C>G, p.(Arg51Gly; the mutation was present in all five family members with the disease and appeared de novo in the first affected generation of the three-generational pedigree. MAB21L2 encodes a protein similar to C. elegans mab-21 cell fate-determining factor; the molecular function of MAB21L2 is largely unknown. To further evaluate the role of MAB21L2, zebrafish mutants carrying a p.(Gln48Serfs*5 frameshift truncation (mab21l2Q48Sfs*5 and a p.(Arg51_Phe52del in-frame deletion (mab21l2R51_F52del were developed with TALEN technology. Homozygous zebrafish embryos from both lines developed variable lens and coloboma phenotypes: mab21l2Q48Sfs*5 embryos demonstrated severe lens and retinal defects with complete lethality while mab21l2R51_F52del mutants displayed a milder lens phenotype and severe coloboma with a small number of fish surviving to adulthood. Protein studies showed decreased stability for the human p.(Arg51Gly and zebrafish p.(Arg51_Phe52del mutant proteins and predicted a complete loss-of-function for the zebrafish p.(Gln48Serfs*5 frameshift truncation. Additionally, in contrast to wild-type human MAB21L2 transcript, mutant p.(Arg51Gly mRNA failed to efficiently rescue the ocular phenotype when injected into mab21l2Q48Sfs*5 embryos, suggesting this allele is functionally deficient. Histology, immunohistochemistry, and in situ hybridization experiments identified retinal invagination defects, an increase in cell death, abnormal proliferation patterns, and altered expression of several ocular markers in the mab21l2 mutants. These findings support the

  12. Multiwavelet Packets and Frame Packets of $L^2(\\mathbb{R}^d)$

    Indian Academy of Sciences (India)

    Biswaranjan Behera

    2001-11-01

    The orthonormal basis generated by a wavelet of $L^2(\\mathbb{R})$ has poor frequency localization. To overcome this disadvantage Coifman, Meyer, and Wickerhauser constructed wavelet packets. We extend this concept to the higher dimensions where we consider arbitrary dilation matrices. The resulting basis of $L^2(\\mathbb{R}^d)$ is called the multiwavelet packet basis. The concept of wavelet frame packet is also generalized to this setting. Further, we show how to construct various orthonormal bases of $L^2(\\mathbb{R}^d)$ from the multiwavelet packets.

  13. Variation of Zr-L2,3 XANES in tetravalent zirconium oxides.

    Science.gov (United States)

    Ikeno, Hidekazu; Krause, Michael; Höche, Thomas; Patzig, Christian; Hu, Yongfeng; Gawronski, Antje; Tanaka, Isao; Rüssel, Christian

    2013-04-24

    Zr-L2,3 XANESs of tetravalent zirconium oxides with different coordination numbers and local symmetries are systematically investigated by ab initio multiplet calculations using fully relativistic molecular spinors for model clusters. Experimental Zr-L2,3 XANESs are obtained for SrZrO3, m-ZrO2 (monoclinic) and t-ZrO2 (tetragonal). The theoretical spectra are in good agreement with the experimental data. The multiplet effects are found to play essential roles in determining the peak shape. The shapes of L3- and L2-edges are systematically different. The intensity ratios of the doublet peaks at both L3- and L2-edges are found to be sensitive to the coordination number of Zr. The ratio can therefore be used to estimate the coordination number of Zr in such oxides.

  14. EX1504L2 Dive12 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L2: Campaign to Address...

  15. EX1205L2 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1205L2: Northeast Canyons and...

  16. EX1504L2 Dive11 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L2: Campaign to Address...

  17. EX1504L2 Dive18 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L2: Campaign to Address...

  18. Spanish heritage language learners vs. L2 learners: What CAF reveals about written proficiency

    Directory of Open Access Journals (Sweden)

    Pablo Camus

    2015-12-01

    Full Text Available Recently, great interest has emerged in identifying the learning needs of heritage language (HL learners. In comparing HL and second language (L2 learners, research suggests that L2 learners outperform HL learners when examining writing abilities (Montrul, 2010; Potowski, 2013. However, complexity, accuracy, and fluency (CAF have been overlooked when examining HL learners’ writing proficiency, and it could provide a better picture of their writing skills in a spontaneous untimed assignment. To address this issue, 28 L2 learners and 18 HL learners completed an untimed written production task on a non-academic subject and their written proficiency was assessed through CAF measures (Norris & Ortega, 2009. Results showed HL learners significantly outperformed L2 learners on two complexity measures: accuracy and fluency. A possible explanation for these findings could be the type of task used (more spontaneous, less-controlled, which taps into a more implicit type of knowledge, favoring HL learners (Bowles, 2011.

  19. Friend or foe? First language (L1 in second/foreign language (L2/FL instruction

    Directory of Open Access Journals (Sweden)

    Channa Liaquat A.

    2017-05-01

    Full Text Available This theoretical review paper investigates the role of first language (L1 in the mainstream scholarship of second/foreign (L2/FL language education in the context of language learning, teaching, and bilingual education. The term ‘mainstream’ refers here to the scholarship that is not informed by sociocultural theory in general and Vygotskian sociocultural theory in particular. The paper later explains a Vygotskian perspective on the use of L1 in L2/FL language education and discusses how the perspective may help content teachers in (a employing L1 in teaching L2/FL content and (b helping L2/FL students to become self-regulative users of the target language.

  20. EX1504L2 Dive09 Ancillary Data Collection including reports, kmls, spreadsheets, images and data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard suite of ancillary data files generated through a scripting process following an ROV dive on NOAA Ship Okeanos Explorer during EX1504L2: Campaign to Address...