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Sample records for achieve high gain

  1. Best Practices for Achieving High, Rapid Reading Gains

    ERIC Educational Resources Information Center

    Carbo, Marie

    2008-01-01

    The percentage of students who read at the proficient level on the National Assessment of Educational Progress (NAEP) has not improved, and is appallingly low. In order for students to achieve high reading gains and become life-long readers, reading comprehension and reading enjoyment must be the top two goals. This article presents several…

  2. Progress on achieving the ICF conditions needed for high gain

    SciTech Connect

    Lindl, J.D.

    1988-12-23

    Progress during the past two years has moved us much closer to demonstrating the scientific and technological requirements for high gain ICF in the laboratory. This progress has been made possible by operating at the third harmonic of 1..mu..m light which dramatically reduces concern about hot electrons and by advances in diagnostics such as 100 ps x-ray framing cameras which greatly increase the data available from each experiment. Making use of many of these new capabilities, major improvements in confinement conditions have been achieved for ICF implosions. In particular, in an optimized hohlraum on Nova, radiation driven implosions with convergence ratio in excess of 30 (volume compression /approximately/3 /times/ 10/sup 4/) have performed essentially as predicted by spherical implosion calculations. This paper presents these results as well as examples of advances in several other areas and discusses the implications for the future of ICF with lasers and heavy ion beam drivers. 8 refs., 10 figs.

  3. Achieving yield gains in wheat.

    PubMed

    Reynolds, Matthew; Foulkes, John; Furbank, Robert; Griffiths, Simon; King, Julie; Murchie, Erik; Parry, Martin; Slafer, Gustavo

    2012-10-01

    Wheat provides 20% of calories and protein consumed by humans. Recent genetic gains are <1% per annum (p.a.), insufficient to meet future demand. The Wheat Yield Consortium brings expertise in photosynthesis, crop adaptation and genetics to a common breeding platform. Theory suggest radiation use efficiency (RUE) of wheat could be increased ~50%; strategies include modifying specificity, catalytic rate and regulation of Rubisco, up-regulating Calvin cycle enzymes, introducing chloroplast CO(2) concentrating mechanisms, optimizing light and N distribution of canopies while minimizing photoinhibition, and increasing spike photosynthesis. Maximum yield expression will also require dynamic optimization of source: sink so that dry matter partitioning to reproductive structures is not at the cost of the roots, stems and leaves needed to maintain physiological and structural integrity. Crop development should favour spike fertility to maximize harvest index so phenology must be tailored to different photoperiods, and sensitivity to unpredictable weather must be modulated to reduce conservative responses that reduce harvest index. Strategic crossing of complementary physiological traits will be augmented with wide crossing, while genome-wide selection and high throughput phenotyping and genotyping will increase efficiency of progeny screening. To ensure investment in breeding achieves agronomic impact, sustainable crop management must also be promoted through crop improvement networks. PMID:22860982

  4. Becoming a Great Teacher of Reading: Achieving High Rapid Reading Gains with Powerful, Differentiated Strategies

    ERIC Educational Resources Information Center

    Carbo, Marie

    2007-01-01

    Literacy expert Marie Carbo pairs identifying each learner's unique reading style with a wide range of differentiated strategies to help all learners experience greater reading success. Using these research-based methods, both novice and experienced teachers can increase reading achievement with all learners, including those who are at-risk,…

  5. Developmental gains in visuospatial memory predict gains in mathematics achievement.

    PubMed

    Li, Yaoran; Geary, David C

    2013-01-01

    Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning. PMID:23936154

  6. Sharing Leadership Responsibilities Results in Achievement Gains

    ERIC Educational Resources Information Center

    Armistead, Lew

    2010-01-01

    Collective, not individual, leadership in schools has a greater impact on student achievement; when principals and teachers share leadership responsibilities, student achievement is higher; and schools having high student achievement also display a vision for student achievement and teacher growth. Those are just a few of the insights into school…

  7. Collapsible high gain antenna

    NASA Technical Reports Server (NTRS)

    Cribb, H. E. (Inventor)

    1973-01-01

    A lightweight small high gain antenna which is capable of being packaged in a collapsed form and automatically expanded when in use is described. The antenna includes a cylindrical housing having a rod with a piston adjacent to one end extending through it. Attached to the outer end of the rod in a normally collapsed state is a helical wire coil. When the gas producing means is activated the piston and rod are shifted outwardly to expand the wire coil. A latch is provided for holding the helical coil in the expanded position.

  8. Helicopter high gain control

    NASA Technical Reports Server (NTRS)

    Cunningham, T. B.; Nunn, E. C.

    1979-01-01

    High gain control is explored through a design study of the CH-47B helicopter. The plans are designed to obtain the maximum bandwidth possible given the hardware constraints. Controls are designed with modal control theory to specific bandwidths and closed loop mode shapes. Comparisons are made to an earlier complementary filter approach. Bandwidth improvement by removal of limitations is explored in order to establish hardware and mechanization options. Improvements in the pitch axis control system and in the rate gyro sensor noise characteristics in all axes are discussed. The use of rotor state feedback is assessed.

  9. How Much Professional Development Is Needed to Effect Positive Gains in K-6 Student Achievement on High Stakes Science Tests?

    ERIC Educational Resources Information Center

    Shymansky, James A.; Wang, Tzu-Ling; Annetta, Leonard A.; Yore, Larry D.; Everett, Susan A.

    2012-01-01

    This paper is a report of a study that examines the relationship between teacher participation in a multi-year, K-6 professional development effort and the "high stakes" science test scores of different student groups in 33 rural mid-west school districts in the USA. The professional development program involved 1,269 elementary school teachers…

  10. Achieving improved cycle efficiency via pressure gain combustors

    SciTech Connect

    Gemmen, R.S.; Janus, M.C.; Richards, G.A.; Norton, T.S.; Rogers, W.A.

    1995-04-01

    As part of the Department of Energy`s Advanced Gas Turbine Systems Program, an investigation is being performed to evaluate ``pressure gain`` combustion systems for gas turbine applications. This paper presents experimental pressure gain and pollutant emission data from such combustion systems. Numerical predictions for certain combustor geometries are also presented. It is reported that for suitable aerovalved pulse combustor geometries studied experimentally, an overall combustor pressure gain of nearly 1 percent can be achieved. It is also shown that for one combustion system operating under typical gas turbine conditions, NO{sub x} and CO emmissions, are about 30 ppmv and 8 ppmv, respectively.

  11. Competence with fractions predicts gains in mathematics achievement.

    PubMed

    Bailey, Drew H; Hoard, Mary K; Nugent, Lara; Geary, David C

    2012-11-01

    Competence with fractions predicts later mathematics achievement, but the codevelopmental pattern between fractions knowledge and mathematics achievement is not well understood. We assessed this codevelopment through examination of the cross-lagged relation between a measure of conceptual knowledge of fractions and mathematics achievement in sixth and seventh grades (N=212). The cross-lagged effects indicated that performance on the sixth grade fractions concepts measure predicted 1-year gains in mathematics achievement (ß=.14, p<.01), controlling for the central executive component of working memory and intelligence, but sixth grade mathematics achievement did not predict gains on the fractions concepts measure (ß=.03, p>.50). In a follow-up assessment, we demonstrated that measures of fluency with computational fractions significantly predicted seventh grade mathematics achievement above and beyond the influence of fluency in computational whole number arithmetic, performance on number fluency and number line tasks, central executive span, and intelligence. Results provide empirical support for the hypothesis that competence with fractions underlies, in part, subsequent gains in mathematics achievement. PMID:22832199

  12. Effects of Collaborative Group Composition and Inquiry Instruction on Reasoning Gains and Achievement in Undergraduate Biology

    PubMed Central

    Jensen, Jamie Lee; Lawson, Anton

    2011-01-01

    This study compared the effectiveness of collaborative group composition and instructional method on reasoning gains and achievement in college biology. Based on initial student reasoning ability (i.e., low, medium, or high), students were assigned to either homogeneous or heterogeneous collaborative groups within either inquiry or didactic instruction. Achievement and reasoning gains were assessed at the end of the semester. Inquiry instruction, as a whole, led to significantly greater gains in reasoning ability and achievement. Inquiry instruction also led to greater confidence and more positive attitudes toward collaboration. Low-reasoning students made significantly greater reasoning gains within inquiry instruction when grouped with other low reasoners than when grouped with either medium or high reasoners. Results are consistent with equilibration theory, supporting the idea that students benefit from the opportunity for self-regulation without the guidance or direction of a more capable peer. PMID:21364101

  13. High current gain transistor laser.

    PubMed

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-01-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge. PMID:27282466

  14. High current gain transistor laser

    NASA Astrophysics Data System (ADS)

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-06-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge.

  15. High current gain transistor laser

    PubMed Central

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-01-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge. PMID:27282466

  16. Hybrid optical antenna with high directivity gain.

    PubMed

    Bonakdar, Alireza; Mohseni, Hooman

    2013-08-01

    Coupling of a far-field optical mode to electronic states of a quantum absorber or emitter is a crucial process in many applications, including infrared sensors, single molecule spectroscopy, and quantum metrology. In particular, achieving high quantum efficiency for a system with a deep subwavelength quantum absorber/emitter has remained desirable. In this Letter, a hybrid optical antenna based on coupling of a photonic nanojet to a metallo-dielectric antenna is proposed, which allows such efficient coupling. A quantum efficiency of about 50% is predicted for a semiconductor with volume of ~λ³/170. Despite the weak optical absorption coefficient of 2000 cm(-1) in the long infrared wavelength of ~8 μm, very strong far-field coupling has been achieved, as evidenced by an axial directivity gain of 16 dB, which is only 3 dB below of theoretical limit. Unlike the common phased array antenna, this structure does not require coherent sources to achieve a high directivity. The quantum efficiency and directivity gain are more than an order of magnitude higher than existing metallic, dielectric, or metallo-dielectric optical antenna. PMID:23903124

  17. High gain Raman amplifier with inherent gain flattening and dispersion compensation

    NASA Astrophysics Data System (ADS)

    Kakkar, Charu; Thyagarajan, K.

    2005-06-01

    We report here an inherently gain-flattened, high-gain discrete Raman fiber amplifier design with 21 dB net gain (±1.4 dB gain ripple) over 25 nm bandwidth. The amplifier design is based on a W-shape highly nonlinear fiber, in which, optimized spectral variation of leakage loss has been used to achieve inherent gain flattening of Raman gain. The proposed fiber has an additional advantage of having a high negative dispersion coefficient (∼-84 ps/km nm) over the operating range of wavelength and thus the designed discrete amplifier module, based on this fiber, is also capable of compensating dispersion accumulated in one span (70 km) of transmission through G.652 fiber. Hence, the designed module is proposed as a composite amplifier and dispersion-compensating unit for 25 nm bandwidth, which is capable of handling both attenuation and dispersion of one span of G. 652 transmission.

  18. Resonator modes in high gain free electron lasers

    SciTech Connect

    Xie, Ming ); Deacon, D.A.G. ); Madey, J.M.J. . Dept. of Physics)

    1989-10-01

    When the gain in a free electron laser is high enough to produce optical guiding, the resonator mode distorts and loses its forward-backward symmetry. We show that the resonator mode in a high gain FEL can be easily constructed using the mode expansion technique taken separately in the interaction and the free-space regions. We propose design strategies to achieve maximal gain and optimal mode quality, and discuss the stability of the optimized mode. 11 refs., 4 figs.

  19. Very high gain Nd:YLF amplifiers

    SciTech Connect

    Knights, M.G.; Thomas, M.D.; Chicklis, E.P.; Rines, G.A.; Seka, W.

    1988-05-01

    The authors report on high gain Nd:YLF rod amplifiers in which single-pass, small signal gains of over 1700 have been obtained along with stored energy densitiesgreater than or equal to0.4J/cm/sup 3/. The ability of Nd:YLF amplifiers to support such gains is a result of high parasitic oscillation thresholds, due primarily to the low refractive index of the material. These results suggest that Nd:YLF is an excellent candidate for amplifiers where high specific stored energies and/or very high gains are required.

  20. High temperature electronic gain device

    DOEpatents

    McCormick, J. Byron; Depp, Steven W.; Hamilton, Douglas J.; Kerwin, William J.

    1979-01-01

    An integrated thermionic device suitable for use in high temperature, high radiation environments. Cathode and control electrodes are deposited on a first substrate facing an anode on a second substrate. The substrates are sealed to a refractory wall and evacuated to form an integrated triode vacuum tube.

  1. Competence with Fractions Predicts Gains in Mathematics Achievement

    ERIC Educational Resources Information Center

    Bailey, Drew H.; Hoard, Mary K.; Nugent, Lara; Geary, David C.

    2012-01-01

    Competence with fractions predicts later mathematics achievement, but the codevelopmental pattern between fractions knowledge and mathematics achievement is not well understood. We assessed this codevelopment through examination of the cross-lagged relation between a measure of conceptual knowledge of fractions and mathematics achievement in sixth…

  2. Explaining Mathematics Achievement Gains in Botswana and South Africa

    ERIC Educational Resources Information Center

    Carnoy, Martin; Arends, Fabian

    2012-01-01

    The purpose of this study is to test empirically whether and how classroom and school factors contribute to student mathematics learning gains in the border region of North West province, South Africa and Southeastern Botswana. Our results suggest that in both regions, improving teaching quality has an important impact on how much mathematics…

  3. The Galileo high gain antenna deployment anomaly

    NASA Technical Reports Server (NTRS)

    Johnson, Michael R.

    1994-01-01

    On April 11, 1991, the Galileo spacecraft executed a sequence that would open the spacecraft's High Gain Antenna. The Antenna's launch restraint had been released just after deployment sequence, the antenna, which opens like an umbrella, never reached the fully deployed position. The analyses and tests that followed allowed a conclusive determination of the likely failure mechanisms and pointed to some strategies to use for recovery of the high gain antenna.

  4. Instructional Conditions in Charter Schools and Students' Mathematics Achievement Gains

    ERIC Educational Resources Information Center

    Berends, Mark; Goldring, Ellen; Stein, Marc; Cravens, Xiu

    2010-01-01

    Since charter school research on student achievement is mixed, many researchers and policy makers advocate looking inside the "black box" of schools to better understand the conditions under which schools of choice may be effective. We begin to address this issue with data from charter schools and a comparison group of traditional public schools.…

  5. Theoretical investigation of the more suitable rare earth to achieve high gain in waveguide based on silica containing silicon nanograins doped with either Nd³+ or Er³+ ions.

    PubMed

    Fafin, Alexandre; Cardin, Julien; Dufour, Christian; Gourbilleau, Fabrice

    2014-05-19

    We present a comparative study of the gain achievement in a waveguide whose active layer is constituted by a silica matrix containing silicon nanograins acting as sensitizer of either neodymium ions (Nd3+) or erbium ions (Er3+). By means of an auxiliary differential equation and finite difference time domain (ADE-FDTD) approach that we developed, we investigate the steady states regime of both rare earths ions and silicon nanograins levels populations as well as the electromagnetic field for different pumping powers ranging from 1 to 104 mW/mm2. Moreover, the achievable gain has been estimated in this pumping range. The Nd3+ doped waveguide shows a higher gross gain per unit length at 1064 nm (up to 30 dB/cm) than the one with Er3+ doped active layer at 1532 nm (up to 2 dB/cm). Taking into account the experimental background losses we demonstrate that a significant positive net gain can only be achieved with the Nd3+ doped waveguide. PMID:24921348

  6. Focusing on Short-Term Achievement Gains Fails to Produce Long-Term Gains

    ERIC Educational Resources Information Center

    Grissmer, David W.; Ober, David R.; Beekman, John A.

    2014-01-01

    The short-term emphasis engendered by No Child Left Behind (NCLB) has focused research predominantly on unraveling the complexities and uncertainties in assessing short-term results, rather than developing methods and assessing results over the longer term. In this paper we focus on estimating long-term gains and address questions important to…

  7. Progress toward high-gain laser fusion

    SciTech Connect

    Storm, E.

    1988-09-28

    A 1985-1986 Review of the US inertial confinement fusion program by the National Academy of Sciences concluded that five more years might be required to obtain enough data to determine the future course of the program. Since then, data from the Nova laser and from the Halite/Centurion program have resolved most of the outstanding problems identified by the NAS review. In particular, we now believe that we can produce a sufficiently uniform target; that we can keep the energy content in hot electrons and high-energy photons low enough (/approximately/1--10% of drive energy, depending on target design) and achieve enough pulse-shaping accuracy (/approximately/10%, with a dynamic range of 100:1) to keep the fuel on a near-Fermi-degenerate adiabat; that we can produce an /approximately/100-Mbar pressure pulse of sufficient uniformity (/approximately/1%), and can we control hydrodynamic instabilities so that the mix of the pusher into the hot spot is low enough to permit marginal ignition. These results are sufficiently encouraging that the US Department of Energy is planning to complete a 10-MJ laboratory microfusion facility to demonstrate high-gain ICF in the laboratory within a decade. 22 refs., 1 fig.

  8. Progress toward high-gain laser fusion

    NASA Astrophysics Data System (ADS)

    Storm, Erik

    1988-09-01

    A 1985 to 1986 Review of the U.S. inertial confinement fusion program by the National Academy of Sciences concluded that five more years might be required to obtain enough data to determine the future course of the program. Since then, data from the Nova laser and from the Halite/Centurion program have resolved most of the outstanding problems identified by the NAS review. In particular, we now believe that we can produce a sufficiently uniform target; that we can keep the energy content in hot electrons and high-energy photons low enough (approximately 1 to 10 percent of drive energy, depending on target design) and achieve enough pulse-shaping accuracy (approximately 10 percent, with a dynamic range of 100:1) to keep the fuel on a near-Fermi-degenerate adiabat; that we can produce an approximately 100-Mbar pressure pulse of sufficient uniformity (approximately 1 percent), and can control hydrodynamic instabilities so that the mix of the pusher into the hot spot is low enough to permit marginal ignition. These results are sufficiently encouraging that DOE is planning to complete a 10-MJ laboratory microfusion facility to demonstrate high-gain ICF in the laboratory within a decade.

  9. An output amplitude configurable wideband automatic gain control with high gain step accuracy

    NASA Astrophysics Data System (ADS)

    Xiaofeng, He; Taishan, Mo; Chengyan, Ma; Tianchun, Ye

    2012-02-01

    An output amplitude configurable wideband automatic gain control (AGC) with high gain step accuracy for the GNSS receiver is presented. The amplitude of an AGC is configurable in order to cooperate with baseband chips to achieve interference suppression and be compatible with different full range ADCs. And what's more, the gain-boosting technology is introduced and the circuit is improved to increase the step accuracy. A zero, which is composed by the source feedback resistance and the source capacity, is introduced to compensate for the pole. The AGC is fabricated in a 0.18 μm CMOS process. The AGC shows a 62 dB gain control range by 1 dB each step with a gain error of less than 0.2 dB. The AGC provides 3 dB bandwidth larger than 80 MHz and the overall power consumption is less than 1.8 mA, and the die area is 800 × 300 μm2.

  10. Effects of Fidelity of Implementation on Science Achievement Gains among English Language Learners

    ERIC Educational Resources Information Center

    Lee, Okhee; Penfield, Randall; Maerten-Rivera, Jaime

    2009-01-01

    This study examined the effect of fidelity of implementation (FOI) on the science achievement gains of third grade students broadly and students with limited literacy in English specifically. The study was conducted in the context of a professional development intervention with elementary school teachers to promote science achievement of ELL…

  11. Gaining Retention and Achievement for Students Program (GRASP): A Faculty Development Program To Increase Student Success.

    ERIC Educational Resources Information Center

    McShannon, Judith

    This study investigated the effects of a faculty development program offered to increase positive interactions between students and faculty and the effects of these interactions on student achievement and retention. The Gaining Retention and Achievement for Students (GRASP) program supports the accreditation process of the Accreditation Board of…

  12. Mechanisms of the Rosetta high gain antenna

    NASA Astrophysics Data System (ADS)

    Pereira, Carlos

    2001-09-01

    This paper describes the antenna pointing mechanism (APM) and the hold down and release mechanism (HRM) used in the high gain antenna of the ROSETTA mission. The hold down and release mechanism consists of three units which compensate the tolerance mismatch between antenna and spacecraft through incorporation of potting rings. Given that the activation mode is pyrotechnic, release shock is a major concern and is minimised through integration of shock absorbers which allow stroking of the separation nuts. The antenna pointing mechanism is a dual drive (azimuth over elevation) unit which allows controlled rotation of the antenna. The drive units incorporate spring loaded end stops to prevent the antenna from hitting the spacecraft, and optical encoders which register the absolute position of the antenna. The pointing and the hold down mechanisms of the ROSETTA antenna are fully qualified and will withstand the high launch loads of the Ariane-5 and the environmental demands of deep space operation.

  13. High resolution BPMS with integrated gain correction system

    SciTech Connect

    Wendt, M.; Briegel, C.; Eddy, N.; Fellenz, B.; Gianfelice, E.; Prieto, P.; Rechenmacher, R.; Voy, D.; Terunuma, N.; Urakawa, J.; /KEK, Tsukuba

    2009-08-01

    High resolution beam position monitors (BPM) are an essential tool to achieve and reproduce a low vertical beam emittance at the KEK Accelerator Test Facility (ATF) damping ring. The ATF damping ring (DR) BPMs are currently upgraded with new high resolution read-out electronics. Based on analog and digital down-conversion techniques, the upgrade includes an automatic gain calibration system to correct for slow drift effects and ensure high reproducible beam position readings. The concept and its technical realization, as well as preliminary results of beam studies are presented.

  14. High gain holmium-doped fibre amplifiers.

    PubMed

    Simakov, Nikita; Li, Zhihong; Jung, Yongmin; Daniel, Jae M O; Barua, Pranabesh; Shardlow, Peter C; Liang, Sijing; Sahu, Jayanta K; Hemming, Alexander; Clarkson, W Andrew; Alam, Shaif-Ul; Richardson, David J

    2016-06-27

    We investigate the operation of holmium-doped fibre amplifiers (HDFAs) in the 2.1 µm spectral region. For the first time we demonstrate a diode-pumped HDFA. This amplifier provides a peak gain of 25 dB at 2040 nm with a 15 dB gain window spanning the wavelength range 2030 - 2100 nm with an external noise figure (NF) of 4-6 dB. We also compare the operation of HDFAs when pumped at 1950 nm and 2008 nm. The 1950 nm pumped HDFA provides 41 dB peak gain at 2060 nm with 15 dB of gain spanning the wavelength range 2050 - 2120 nm and an external NF of 7-10 dB. By pumping at the longer wavelength of 2008 nm the gain bandwidth of the amplifier is shifted to longer wavelengths and using this architecture a HDFA was demonstrated with a peak gain of 39 dB at 2090 nm and 15 dB of gain spanning the wavelength range 2050 - 2150 nm. The external NF over this wavelength range was 8-14 dB. PMID:27410557

  15. Cathode driven high gain crossed-field amplifier

    NASA Astrophysics Data System (ADS)

    1983-07-01

    The objective of this three-phase program is to achieve the design of a cathode driven high gain re-entrant Crossed Field Amplifier capable of meeting the parameters of Raytheon Company specification No. 968838 dated 10 May 1978. The effort includes the fabrication and test of three developmental and four final configuration tubes. One final configuration tube will be life tested and two will be delivered to the Navy. The tasks discussed during this report period relate to the cold tests performed on various subassemblies of model no. 4 and on the sealed-in model no. 4 of the S-band high gain cathode driven crossed field amplifier. Based on the performance of model no. 3 certain remedial measures have been implemented in model no. 4 that have resulted in the elimination of key resonances within the tube and an improvement in the isolation between the cathode and anode circuits.

  16. Possibility of a high-power, high-gain amplifier FEL

    SciTech Connect

    Nguyen, D. C.; Freund, H. P.

    2002-01-01

    High-gain amplifier FEL offer many unique advantages such as robust operation without a high-Q optical cavity and potentially high extraction eaciencies with the use of tapered wigglers. Although a high average power, cw amplifier FEL has not been demonstrated, many key physics issues such as electron beam brightness requirements, single-pass gains, saturation, etc. have been resolved. In this paper, we study the feasibility of a high-power FEL based on the high-gain amplifier concept. We show that with suitable electron beam parameters, i.e. high peak current, low emittance, low energy spread, and sufficient tapered wiggler length, peak output power of 1 QW and optical pulse energy of 8 mJ can be achieved. We also outline a possible configuration of a high-power, high-gain amplifier FEL with energy recovery.

  17. CLASS SIZE AND ACHIEVEMENT GAINS IN SEVENTH- AND EIGHTH-GRADE ENGLISH AND MATHEMATICS.

    ERIC Educational Resources Information Center

    JOHNSON, MAURITZ; SCRIVEN, ELDON

    USING DATA OBTAINED BY THE QUALITY MEASUREMENT PROJECT ON SOME 70,000 PUPILS, THIS STUDY ATTEMPTED TO PRODUCE EVIDENCE REGARDING THE INFLUENCE OF CLASS SIZE AND CLASS HOMOGENEITY ON ACHIEVEMENT GAINS IN GRADES 7 AND 8. A TOTAL OF 130 ENGLISH AND 135 MATHEMATICS CLASSES CLASSIFIED ACCORDING TO SIZE AND HOMOGENEITY WERE EXAMINED. THE READING…

  18. Quality of Teaching Mathematics and Learning Achievement Gains: Evidence from Primary Schools in Kenya

    ERIC Educational Resources Information Center

    Ngware, Moses W.; Ciera, James; Musyoka, Peter K.; Oketch, Moses

    2015-01-01

    This paper examines the contribution of quality mathematics teaching to student achievement gains. Quality of mathematics teaching is assessed through teacher demonstration of the five strands of mathematical proficiency, the level of cognitive task demands, and teacher mathematical knowledge. Data is based on 1907 grade 6 students who sat for the…

  19. High-Gain High-Field Fusion Plasma

    NASA Astrophysics Data System (ADS)

    Li, Ge

    2015-10-01

    A Faraday wheel (FW)—an electric generator of constant electrical polarity that produces huge currents—could be implemented in an existing tokamak to study high-gain high-field (HGHF) fusion plasma, such as the Experimental Advanced Superconducting Tokamak (EAST). HGHF plasma can be realized in EAST by updating its pulsed-power system to compress plasma in two steps by induction fields; high gains of the Lawson trinity parameter and fusion power are both predicted by formulating the HGHF plasma. Both gain rates are faster than the decrease rate of the plasma volume. The formulation is checked by earlier ATC tests. Good agreement between theory and tests indicates that scaling to over 10 T at EAST may be possible by two-step compressions with a compression ratio of the minor radius of up to 3. These results point to a quick new path of fusion plasma study, i.e., simulating the Sun by EAST.

  20. High-Gain High-Field Fusion Plasma.

    PubMed

    Li, Ge

    2015-01-01

    A Faraday wheel (FW)-an electric generator of constant electrical polarity that produces huge currents-could be implemented in an existing tokamak to study high-gain high-field (HGHF) fusion plasma, such as the Experimental Advanced Superconducting Tokamak (EAST). HGHF plasma can be realized in EAST by updating its pulsed-power system to compress plasma in two steps by induction fields; high gains of the Lawson trinity parameter and fusion power are both predicted by formulating the HGHF plasma. Both gain rates are faster than the decrease rate of the plasma volume. The formulation is checked by earlier ATC tests. Good agreement between theory and tests indicates that scaling to over 10 T at EAST may be possible by two-step compressions with a compression ratio of the minor radius of up to 3. These results point to a quick new path of fusion plasma study, i.e., simulating the Sun by EAST. PMID:26507314

  1. Preschool Interpersonal Relationships Predict Kindergarten Achievement: Mediated by Gains in Emotion Knowledge

    PubMed Central

    Torres, Marcela M.; Domitrovich, Celene E.; Bierman, Karen L.

    2016-01-01

    Using longitudinal data, this study tested a model in which preschool interpersonal relationships promoted kindergarten achievement in a pathway mediated by growth in emotion knowledge. The sample included 164 children attending Head Start (14% Hispanic-American, 30% African-American, 56% Caucasian; 56% girls). Preschool interpersonal relationships were indexed by student-teacher relationship closeness and positive peer interactions. Two measures of emotion knowledge (identifying emotions in photographs, recognizing emotions in stories) were assessed at the start and end of the preschool year. Structural equation models revealed that positive interpersonal relationships (with teachers and peers) predicted gains in emotion knowledge (identification, recognition) during the preschool year. Positive interpersonal relationships in preschool also predicted kindergarten achievement (controlling for initial preschool achievement); however, this association was mediated by gains in emotion knowledge during the preschool year. Implications are discussed for school readiness programs serving economically-disadvantaged children.

  2. Stacking nonenzymatic circuits for high signal gain

    PubMed Central

    Chen, Xi; Briggs, Neima; McLain, Jeremy R.; Ellington, Andrew D.

    2013-01-01

    Signal amplification schemes that do not rely on protein enzymes show great potential in areas as abstruse as DNA computation and as applied as point-of-care molecular diagnostics. Toehold-mediated strand displacement, a programmable form of dynamic DNA hybridization, can be used to design powerful amplification cascades that can achieve polynomial or exponential amplification of input signals. However, experimental implementation of such amplification cascades has been severely hindered by circuit leakage due to catalyst-independent side reactions. In this study, we systematically analyzed the origins, characteristics, and outcomes of circuit leakage in amplification cascades and devised unique methods to obtain high-quality DNA circuits that exhibit minimal leakage. We successfully implemented a two-layer cascade that yielded 7,000-fold signal amplification and a two-stage, four-layer cascade that yielded upward of 600,000-fold signal amplification. Implementation of these unique methods and design principles should greatly empower molecular programming in general and DNA-based molecular diagnostics in particular. PMID:23509255

  3. High gain feedback and telerobotic tracking

    NASA Technical Reports Server (NTRS)

    Koditschek, D. E.

    1987-01-01

    Asymptotically stable linear time invariant systems are capable of tracking arbitrary reference signals with a bounded error proportional to the magnitude of the reference signal (and its derivatives). It is shown that a similar property holds for a general class of nonlinear dynamical systems which includes all robots. As in the linear case, the error bound may be made arbitrarily small by increasing the magnitude of the feedback gains which stabilize the system.

  4. High gain GaAs photoconductive semiconductor switches: Switch longevity

    SciTech Connect

    Loubriel, G.M.; Zutavern, F.J.; Mar, A.

    1998-07-01

    Optically activated, high gain GaAs switches are being tested for many different pulsed power applications that require long lifetime (longevity). The switches have p and n contact metallization (with intentional or unintentional dopants) configured in such a way as to produce p-i-n or n-i-n switches. The longevity of the switches is determined by circuit parameters and by the ability of the contacts to resist erosion. This paper will describe how the switches performed in test-beds designed to measure switch longevity. The best longevity was achieved with switches made with diffused contacts, achieving over 50 million pulses at 10 A and over 2 million pulses at 80 A.

  5. Mathematics Achievement in High- and Low-Achieving Secondary Schools

    ERIC Educational Resources Information Center

    Mohammadpour, Ebrahim; Shekarchizadeh, Ahmadreza

    2015-01-01

    This paper identifies the amount of variance in mathematics achievement in high- and low-achieving schools that can be explained by school-level factors, while controlling for student-level factors. The data were obtained from 2679 Iranian eighth graders who participated in the 2007 Trends in International Mathematics and Science Study. Of the…

  6. High-Gain High-Field Fusion Plasma

    PubMed Central

    Li, Ge

    2015-01-01

    A Faraday wheel (FW)—an electric generator of constant electrical polarity that produces huge currents—could be implemented in an existing tokamak to study high-gain high-field (HGHF) fusion plasma, such as the Experimental Advanced Superconducting Tokamak (EAST). HGHF plasma can be realized in EAST by updating its pulsed-power system to compress plasma in two steps by induction fields; high gains of the Lawson trinity parameter and fusion power are both predicted by formulating the HGHF plasma. Both gain rates are faster than the decrease rate of the plasma volume. The formulation is checked by earlier ATC tests. Good agreement between theory and tests indicates that scaling to over 10 T at EAST may be possible by two-step compressions with a compression ratio of the minor radius of up to 3. These results point to a quick new path of fusion plasma study, i.e., simulating the Sun by EAST. PMID:26507314

  7. Epitaxial design of ultra high power tunable laser gain section

    NASA Astrophysics Data System (ADS)

    Zhang, Yaping; Benson, Trevor M.

    2005-09-01

    High power widely tunable lasers are extremely desirable for telecom applications as a replacement for distributed feedback (DFB) lasers in wavelength division multiplexing (WDM) systems, due to their dynamic provision properties. They are also sought after for many other applications, such as phased radar systems, optical switching and routing. This paper introduces novel design ideas and approaches on how to achieve ultra high power in the design of an InGaAsP-InP based widely tunable laser gain section. The inventive ideas are basically composed of two parts. Firstly, to increase the facet optical output power by the inclusion of an InP spacer layer below the ridge and above the multiple quantum wells (MQWs) stack, in order to have extra freedom in the control of widening the single mode ridge width. Secondly, to reduce the free-carrier absorption loss by the inclusion of a bulk balance layer structure below the MQWs stack and above the buffer layer, so as to largely shift the optical mode distribution to the intrinsic and n-doped side of the epilayer structure where the free-carrier absorption loss is lower than that of the p-doped side. Simulation results show that the proposed epilayer designs of the ultra high power gain sections would greatly increase the facet optical output power of a tunable laser, by up to about 80%. It should be noted that these novel epilayer design ideas and approaches developed for the gain section are applicable to the designs of ultra high power DFB lasers and other InGaAsP-InP based lasers.

  8. Intracavity gain shaping in millijoule-level, high gain Ho:YLF regenerative amplifiers.

    PubMed

    Murari, Krishna; Cankaya, Huseyin; Kroetz, Peter; Cirmi, Giovanni; Li, Peng; Ruehl, Axel; Hartl, Ingmar; Kärtner, Franz X

    2016-03-15

    We demonstrate intracavity gain shaping inside a 2 μm Ho:YLF regenerative amplifier with a spectral bandwidth of 2.9 nm broadened to 5.4 nm, corresponding to Fourier-limited pulses of 1 ps duration. The intracavity gain shaping is achieved by using a simple etalon, which acts as a frequency-selective filter. The output of the regenerative amplifier is amplified by a single-pass amplifier, and we achieve total energy of 2.2 mJ and pulse duration of 2.4 ps at 1 kHz with pulse fluctuations <1%. The amplifier chain is seeded by a home-built mode-locked holmium-doped fiber oscillator. PMID:26977647

  9. Student Achievement Levels Raised at Chandler High School.

    ERIC Educational Resources Information Center

    Profiles, Programs & Products, 1983

    1983-01-01

    Chandler (Arizona) High School has reported a dramatic increase in student achievement levels since implementing a number of management, curriculum, and discipline policy changes. Among the program changes that contributed to these gains are: (1) creation of a positive school environment, with high expectations for teachers, emphasis on high…

  10. Design of a high linearity and high gain accuracy analog baseband circuit for DAB receiver

    NASA Astrophysics Data System (ADS)

    Li, Ma; Zhigong, Wang; Jian, Xu; Yiqiang, Wu; Junliang, Wang; Mi, Tian; Jianping, Chen

    2015-02-01

    An analog baseband circuit of high linearity and high gain accuracy for a digital audio broadcasting receiver is implemented in a 0.18-μm RFCMOS process. The circuit comprises a 3rd-order active-RC complex filter (CF) and a programmable gain amplifier (PGA). An automatic tuning circuit is also designed to tune the CF's pass band. Instead of the class-A fully differential operational amplifier (FDOPA) adopted in the conventional CF and PGA design, a class-AB FDOPA is specially employed in this circuit to achieve a higher linearity and gain accuracy for its large current swing capability with lower static current consumption. In the PGA circuit, a novel DC offset cancellation technique based on the MOS resistor is introduced to reduce the settling time significantly. A reformative switching network is proposed, which can eliminate the switch resistor's influence on the gain accuracy of the PGA. The measurement result shows the gain range of the circuit is 10-50 dB with a 1-dB step size, and the gain accuracy is less than ±0.3 dB. The OIP3 is 23.3 dBm at the gain of 10 dB. Simulation results show that the settling time is reduced from 100 to 1 ms. The image band rejection is about 40 dB. It only draws 4.5 mA current from a 1.8 V supply voltage.

  11. High gain durable anti-reflective coating

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Colson, Thomas E.; Gonsalves, Peter R.; Abrams, Ze'ev R.

    2016-07-26

    Disclosed herein are polysilsesquioxane-based anti-reflective coating (ARC) compositions, methods of preparation, and methods of deposition on a substrate. In one embodiment, the polysilsesquioxane of this disclosure is prepared in a two-step process of acid catalyzed hydrolysis of organoalkoxysilane followed by addition of tetralkoxysilane that generates silicone polymers with >40 mol % silanol based on Si-NMR. These high silanol siloxane polymers are stable and have a long shelf-life in polar organic solvents at room temperature. Also disclosed are low refractive index ARC made from these compositions with and without additives such as porogens, templates, thermal radical initiator, photo radical initiators, crosslinkers, Si--OH condensation catalyst and nano-fillers. Also disclosed are methods and apparatus for applying coatings to flat substrates including substrate pre-treatment processes, coating processes and coating curing processes including skin-curing using hot-air knives. Also disclosed are coating compositions and formulations for highly tunable, durable, highly abrasion-resistant functionalized anti-reflective coatings.

  12. Executive function skills and academic achievement gains in prekindergarten: Contributions of learning-related behaviors.

    PubMed

    Nesbitt, Kimberly Turner; Farran, Dale Clark; Fuhs, Mary Wagner

    2015-07-01

    Although research suggests associations between children's executive function skills and their academic achievement, the specific mechanisms that may help explain these associations in early childhood are unclear. This study examined whether children's (N = 1,103; M age = 54.5 months) executive function skills at the beginning of prekindergarten (pre-K) predict their learning-related behaviors in the classroom and whether these behaviors then mediate associations between children's executive function skills and their pre-K literacy, language, and mathematic gains. Learning-related behaviors were quantified in terms of (a) higher levels of involvement in learning opportunities; (b) greater frequency of participation in activities that require sequential steps; (c) more participation in social-learning interactions; and (d) less instances of being unoccupied, disruptive, or in time out. Results indicated that children's learning-related behaviors mediated associations between executive function skills and literacy and mathematics gains through children's level of involvement, sequential learning behaviors, and disengagement from the classroom. The implications of the findings for early childhood education are discussed. PMID:26010383

  13. Student Achievement Levels Climb at Ribault Senior High School.

    ERIC Educational Resources Information Center

    Profiles, Programs & Products, 1983

    1983-01-01

    Ribault (Florida) Senior High School has reported a dramatic increase in student achievement levels since implementing a comprehensive college preparation curriculum. Among the program changes that contributed to those gains are: (1) the establishment and consistent enforcement of a strong discipline program, including rules for student conduct, a…

  14. A 1 to 18 GHz high gain ultra-broadband amplifier with temperature compensation

    NASA Astrophysics Data System (ADS)

    Ariel, D.; Thibout, T.; Lacombe, J. L.

    1989-05-01

    Design and performance of a high gain ultra-broadband hybrid amplifier with temperature compensation are presented. The amplifier consists of six distributed amplifier stages using GaAs FETs. Design emphasis was on minimizing gain variations with temperature; this was achieved by biasing the gates of the FETs with a temperature varying voltage. The amplifier exhibits a gain of 35 dB with a maximum deviation of + or - 4 dB over the frequency range from 1 to 18 GHz and the temperature range from -55 to +85 C. The gain flatness and temperature stability performance of this amplifier make it useful for EW subsystem applications.

  15. Computer simulation of space station computer steered high gain antenna

    NASA Technical Reports Server (NTRS)

    Beach, S. W.

    1973-01-01

    The mathematical modeling and programming of a complete simulation program for a space station computer-steered high gain antenna are described. The program provides for reading input data cards, numerically integrating up to 50 first order differential equations, and monitoring up to 48 variables on printed output and on plots. The program system consists of a high gain antenna, an antenna gimbal control system, an on board computer, and the environment in which all are to operate.

  16. Writing Project Professional Development Continues to Yield Gains in Student Writing Achievement. Research Brief No. 2

    ERIC Educational Resources Information Center

    National Writing Project (NJ1), 2010

    2010-01-01

    The National Writing Project (NWP) has expanded its national portfolio of research projects conducted at local Writing Project sites to 16 studies that examine professional development, teacher practices, and student writing achievement. NWP sites emphasize common principles of high-quality instruction and the professional development necessary to…

  17. Studies of high-gain microchannel plate photomultipliers

    SciTech Connect

    Oba, K.; Rehak, P.

    1980-01-01

    The characteristics and performance of several kinds of high-gain micro-channel plate photomultipliers have been investigated. Special attention was directed toward (1) lifetime studies, (2) performance in the magnetic field, and (3) timing properties. Lifetime studies include separate investigations of the photocathode quantum efficiency degradation caused by ion feedback, and the deterioration of the micro-channel plate gain. The dependence of the micro-channel plate photomultiplier gain on the intensity and the direction of the magnetic field (up to 7 kGauss) is reported.

  18. Nano-engineered ultra-high-gain microchannel plates

    NASA Astrophysics Data System (ADS)

    Beaulieu, D. R.; Gorelikov, D.; de Rouffignac, P.; Saadatmand, K.; Stenton, K.; Sullivan, N.; Tremsin, A. S.

    2009-08-01

    Highly localized and very fast electron amplification of microchannel plates (MCPs) enables a large number of high-resolution and high-sensitivity detection technologies, which provide spatial and/or temporal information for each detected photon/electron/ion/neutron. Although there has been significant progress in photocathode and readout technologies the MCPs themselves have not evolved much from the technology developed several decades ago. Substantial increases in the gain of existing MCP technology have been accomplished by utilizing state-of-the-art processes developed for nano-engineered structures. The gain of treated MCPs with aspect ratio of 40:1 is reproducibly measured to reach unprecedented values of 2×10 5. This gain enhancement is shown to be stable during MCP operation. In addition, the initial experiments indicate improved stability of gain as a function of extracted charge and MCP storage conditions. We also present results from a fully independent thin-film process for manufacturing non-lead glass MCPs using engineered thin films for both the resistive and emissive layers. These substrate-independent MCPs show high gain, less gain degradation with extracted charge, and greater pore-to-pore and plate-to-plate uniformity than has been possible with conventional lead glass structures.

  19. Self Regulated Learning of High Achievers

    ERIC Educational Resources Information Center

    Rathod, Ami

    2010-01-01

    The study was conducted on high achievers of Senior Secondary school. Main objectives were to identify the self regulated learners among the high achievers, to find out dominant components and characteristics operative in self regulated learners and to compare self regulated learning of learners with respect to their subject (science and non…

  20. The Constraints of Poverty on High Achievement

    ERIC Educational Resources Information Center

    Burney, Virginia H.; Beilke, Jayne R.

    2008-01-01

    Research studies on school success often focus on the impact of discrete elements such as race, culture, ethnicity, gender, language, or school location on high achievement. The condition of poverty, however, may be the most important of all student differences in relation to high achievement; although not all schools have racial diversity, nearly…

  1. High gain amplifiers: Power oscillations and harmonic generation

    SciTech Connect

    Dattoli, G.; Ottaviani, P. L.; Pagnutti, S.

    2007-08-01

    We discuss the power oscillations in saturated high gain free electron laser amplifiers and show that the relevant period can be written in terms of the gain length. We use simple arguments following from the solution of the pendulum equation in terms of Jacobi elliptic functions. Nontrivial effects due to nonlinear harmonic generation and inhomogeneous broadening are discussed too, as well as the saturated dynamics of short pulses.

  2. Graphene/GaSe-Nanosheet Hybrid: Towards High Gain and Fast Photoresponse.

    PubMed

    Lu, Rongtao; Liu, Jianwei; Luo, Hongfu; Chikan, Viktor; Wu, Judy Z

    2016-01-01

    While high photoconductive gain has been recently achieved in graphene-based hybrid phototransistors using semiconductor two-dimensional transition/post-transition metal dichalcogenides or quantum dots sensitizers, obtaining fast photoresponse simutaneously remains a challenge that must be addressed for practical applications. In this paper we report a graphene/GaSe nanosheets hybrid photodetector, in which GaSe nanosheets provide a favorable geometric link to graphene conductive layer through van Der Waals force. After a vacuum annealing process, a high gain in exceeding 10(7) has been obtained simitaneously with a dynamic response time of around 10 ms for both light on and off. We attribute the high performance to the elimination of possible deep charge traps, most probably at the graphene/GaSe nanosheets interface. This result demonstrates high photoconductive gain and fast photoresponse can be achieved simultaneously and a clean interface is the key to the high performance of these hybrid devices. PMID:26776942

  3. Graphene/GaSe-Nanosheet Hybrid: Towards High Gain and Fast Photoresponse

    NASA Astrophysics Data System (ADS)

    Lu, Rongtao; Liu, Jianwei; Luo, Hongfu; Chikan, Viktor; Wu, Judy Z.

    2016-01-01

    While high photoconductive gain has been recently achieved in graphene-based hybrid phototransistors using semiconductor two-dimensional transition/post-transition metal dichalcogenides or quantum dots sensitizers, obtaining fast photoresponse simutaneously remains a challenge that must be addressed for practical applications. In this paper we report a graphene/GaSe nanosheets hybrid photodetector, in which GaSe nanosheets provide a favorable geometric link to graphene conductive layer through van Der Waals force. After a vacuum annealing process, a high gain in exceeding 107 has been obtained simitaneously with a dynamic response time of around 10 ms for both light on and off. We attribute the high performance to the elimination of possible deep charge traps, most probably at the graphene/GaSe nanosheets interface. This result demonstrates high photoconductive gain and fast photoresponse can be achieved simultaneously and a clean interface is the key to the high performance of these hybrid devices.

  4. Graphene/GaSe-Nanosheet Hybrid: Towards High Gain and Fast Photoresponse

    PubMed Central

    Lu, Rongtao; Liu, Jianwei; Luo, Hongfu; Chikan, Viktor; Wu, Judy Z.

    2016-01-01

    While high photoconductive gain has been recently achieved in graphene-based hybrid phototransistors using semiconductor two-dimensional transition/post-transition metal dichalcogenides or quantum dots sensitizers, obtaining fast photoresponse simutaneously remains a challenge that must be addressed for practical applications. In this paper we report a graphene/GaSe nanosheets hybrid photodetector, in which GaSe nanosheets provide a favorable geometric link to graphene conductive layer through van Der Waals force. After a vacuum annealing process, a high gain in exceeding 107 has been obtained simitaneously with a dynamic response time of around 10 ms for both light on and off. We attribute the high performance to the elimination of possible deep charge traps, most probably at the graphene/GaSe nanosheets interface. This result demonstrates high photoconductive gain and fast photoresponse can be achieved simultaneously and a clean interface is the key to the high performance of these hybrid devices. PMID:26776942

  5. ZnO nanowire UV photodetectors with high internal gain.

    PubMed

    Soci, C; Zhang, A; Xiang, B; Dayeh, S A; Aplin, D P R; Park, J; Bao, X Y; Lo, Y H; Wang, D

    2007-04-01

    ZnO nanowire (NW) visible-blind UV photodetectors with internal photoconductive gain as high as G approximately 108 have been fabricated and characterized. The photoconduction mechanism in these devices has been elucidated by means of time-resolved measurements spanning a wide temporal domain, from 10-9 to 102 s, revealing the coexistence of fast (tau approximately 20 ns) and slow (tau approximately 10 s) components of the carrier relaxation dynamics. The extremely high photoconductive gain is attributed to the presence of oxygen-related hole-trap states at the NW surface, which prevents charge-carrier recombination and prolongs the photocarrier lifetime, as evidenced by the sensitivity of the photocurrrent to ambient conditions. Surprisingly, this mechanism appears to be effective even at the shortest time scale investigated of t < 1 ns. Despite the slow relaxation time, the extremely high internal gain of ZnO NW photodetectors results in gain-bandwidth products (GB) higher than approximately 10 GHz. The high gain and low power consumption of NW photodetectors promise a new generation of phototransistors for applications such as sensing, imaging, and intrachip optical interconnects. PMID:17358092

  6. Characteristics of current filamentation in high gain photoconductive semiconductor switching

    SciTech Connect

    Zutavern, F J; Loubriel, G M; O'Malley, M W; Helgeson, W D; McLaughlin, D L; Denison, G J

    1992-01-01

    Characteristics of current filamentation are reported for high gain photoconductive semiconductor switches (PCSS). Infrared photoluminescence is used to monitor carrier recombination radiation during fast initiation of high gain switching in large (1.5 cm gap) lateral GaAs PCSS. Spatial modulation of the optical trigger, a 200--300 ps pulse width laser, is examined. Effects on the location and number of current filaments, rise time, and delay to high gain switching, minimum trigger energy, and degradation of switch contacts are presented. Implications of these measurements for the theoretical understanding and practical development of these switches are discussed. Efforts to increase current density and reduce switch size and optical trigger energy requirements are described. Results from contact development and device lifetime testing are presented and the impact of these results on practical device applications is discussed.

  7. Catholic High Schools and Rural Academic Achievement.

    ERIC Educational Resources Information Center

    Sander, William

    1997-01-01

    A study of national longitudinal data examined effects of rural Catholic high schools on mathematics achievement, high school graduation rates, and the likelihood that high school graduates attend college. Findings indicate that rural Catholic high schools had a positive effect on mathematics test scores and no effect on graduation rates or rates…

  8. Effects of Partner's Ability on the Achievement and Conceptual Organization of High-Achieving Fifth-Grade Students.

    ERIC Educational Resources Information Center

    Carter, Glenda; Jones, M. Gail; Rua, Melissa

    2003-01-01

    Investigates high-achieving fifth-grade students' achievement gains and conceptual reorganization on convection. Features an instructional sequence of three dyadic inquiry investigations related to convection currents as well as pre- and post-assessment consisting of a multiple-choice test, a card sorting task, construction of a concept map, and…

  9. Caustic Singularities Of High-Gain, Dual-Shaped Reflectors

    NASA Technical Reports Server (NTRS)

    Galindo, Victor; Veruttipong, Thavath W.; Imbriale, William A.; Rengarajan, Sambiam

    1991-01-01

    Report presents study of some sources of error in analysis, by geometric theory of diffraction (GTD), of performance of high-gain, dual-shaped antenna reflector. Study probes into underlying analytic causes of singularity, with view toward devising and testing practical methods to avoid problems caused by singularity. Hybrid physical optics (PO) approach used to study near-field spillover or noise-temperature characteristics of high-gain relector antenna efficiently and accurately. Report illustrates this approach and underlying principles by presenting numerical results, for both offset and symmetrical reflector systems, computed by GTD, PO, and PO/GO methods.

  10. The Relationship between STAR Math Score Gains and Academic Achievement in Math

    ERIC Educational Resources Information Center

    Churchwell, Don Wesley

    2009-01-01

    This study examined the relationship between STAR Math gains and TCAP composite scores. The purpose of this study was to determine if there was a significant relationship between STAR Math pretest and posttest gains over the course of the 2005-2006 academic year through the use of the STAR Math software program and TCAP math composite scores at…

  11. High gain proportional rf control stability at TESLA cavities

    NASA Astrophysics Data System (ADS)

    Vogel, Elmar

    2007-05-01

    Fast proportional rf control is used as the basis for rf field regulation in actual linear accelerator projects like the international linear collider (ILC) and the European x-ray free electron laser (XFEL) based on TESLA technology. Additional control loops improve the field regulation by treating repetitive effects and compensating the beam loading. Nevertheless, the ability for high gain operation of the fast loops is desirable for the strong suppression of nonpredictive and nonrepetitive disturbances. TESLA cavities host nine fundamental modes (FMs) where only one is used for beam acceleration. The unwanted FMs have a significant influence on the proportional rf control loop stability at high gains. Within this paper, the stability of proportional rf control loops taking the FMs and digitalization effects into account will be discussed in detail together with measures enabling a significant increase of the gain values.

  12. Large-Scale High-Resolution Simulations of High Gain Direct-Drive ICF targets

    NASA Astrophysics Data System (ADS)

    Schmitt, Andrew J.

    2003-10-01

    High gain directly-driven targets have been designed using new concepts that mitigate the Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities. Two-dimensional simulations of pellets using these techniques (e.g., "picket" laser pulses) show that high (>100) gain can survive in the face of the hydro instabilities seeded by laser and pellet imperfections. These new designs appear to be substantially more robust than earlier designs. We are using the highly-parallelized sliding-zone Eulerian FAST radiation hydrocode to study yield degradation in these designs. The special challenge in performing these simulations for direct-drive laser ICF is that both high resolution and large dynamic range are needed. High resolution of the whole target is needed to represent all of the scales important during the implosion. A large dynamic range is required to resolve the initially tiny surface and imprint perturbations that grow exponentially during acceleration. We find that the rapid growth of the shell perturbations during the acceleration phase is in good agreement with simple RT modeling before significant nonlinearity occurs. However, the Richtmyer-Meshkov growth during the early pellet compression phase poses a challenge particularly for multimode simulations because of the extremely small initial amplitude for each mode. We will present the results from large-scale pellet implosion simulations, and discuss the challenges and progress achieved in the numerical modeling of these high gain designs.

  13. Undergraduates Achieve Learning Gains in Plant Genetics through Peer Teaching of Secondary Students

    PubMed Central

    Chrispeels, H. E.; Klosterman, M. L.; Martin, J. B.; Lundy, S. R.; Watkins, J. M.; Gibson, C. L.

    2014-01-01

    This study tests the hypothesis that undergraduates who peer teach genetics will have greater understanding of genetic and molecular biology concepts as a result of their teaching experiences. Undergraduates enrolled in a non–majors biology course participated in a service-learning program in which they led middle school (MS) or high school (HS) students through a case study curriculum to discover the cause of a green tomato variant. The curriculum explored plant reproduction and genetic principles, highlighting variation in heirloom tomato fruits to reinforce the concept of the genetic basis of phenotypic variation. HS students were taught additional activities related to mole­cular biology techniques not included in the MS curriculum. We measured undergraduates’ learning outcomes using pre/postteaching content assessments and the course final exam. Undergraduates showed significant gains in understanding of topics related to the curriculum they taught, compared with other course content, on both types of assessments. Undergraduates who taught HS students scored higher on questions specific to the HS curriculum compared with undergraduates who taught MS students, despite identical lecture content, on both types of assessments. These results indicate the positive effect of service-learning peer-teaching experiences on undergraduates’ content knowledge, even for non–science major students. PMID:25452487

  14. Dispersion relations for 1D high-gain FELs

    SciTech Connect

    Webb, S.D.; Litvinenko, V.N.

    2010-08-23

    We present analytical results for the one-dimensional dispersion relation for high-gain FELs. Using kappa-n distributions, we obtain analytical relations between the dispersion relations for various order kappa distributions. Since an exact solution exists for the kappa-1 (Lorentzian) distribution, this provides some insight into the number of modes on the way to the Gaussian distribution.

  15. Radiation Response of Emerging High Gain, Low Noise Detectors

    NASA Technical Reports Server (NTRS)

    Becker, Heidi N.; Farr, William H; Zhu, David Q.

    2007-01-01

    Data illustrating the radiation response of emerging high gain, low noise detectors are presented. Ionizing dose testing of silicon internal discrete avalanche photodiodes, and 51-MeV proton testing of InGaAs/InAlAs avalanche photodiodes operated in Geiger mode are discussed.

  16. On Point Designs for High Gain Fast Ignition

    SciTech Connect

    Key, M; Akli, K; Beg, F; Betti, R; Clark, D S; Chen, S N; Freeman, R R; Hansen, S; Hatchett, S P; Hey, D; King, J A; Kemp, A J; Lasinski, B F; Langdon, B; Ma, T; MacKinnon, A J; Meyerhofer, D; Patel, P K; Pasley, J; Phillips, T; Stephens, R B; Stoeckl, C; Foord, M; Tabak, M; Theobald, W; Storm, M; Town, R J; Wilks, S C; VanWoerkom, L; Wei, M S; Weber, R; Zhang, B

    2007-09-27

    Fast ignition research has reached the stage where point designs are becoming crucial to the identification of key issues and the development of projects to demonstrate high gain fast ignition. The status of point designs for cone coupled electron fast ignition and some of the issues they highlight are discussed.

  17. The Effects of Explicit Teaching of Metastrategic Knowledge on Low- And High-Achieving Students

    ERIC Educational Resources Information Center

    Zohar, Anat; Peled, Bracha

    2008-01-01

    This study assessed the effects of explicit teaching of metastrategic knowledge (MSK) on gains of low-achieving (LA) and high-achieving (HA) 5th grade students (N=41). Gains in reasoning scores of students from the Experimental group (compared to students from the control group) were obtained on the strategic and on the metastrategic level. Gains…

  18. Ultra-high gain diffusion-driven organic transistor

    NASA Astrophysics Data System (ADS)

    Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

    2016-02-01

    Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal-semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics.

  19. Ultra-high gain diffusion-driven organic transistor

    PubMed Central

    Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

    2016-01-01

    Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal–semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics. PMID:26829567

  20. Attainment of a high gain in a disk amplifying stage with neodymium phosphate glass elements

    SciTech Connect

    Voronich, Ivan N; Garanin, Sergey G; Zaretskii, Aleksei I; Ignat'ev, Ivan V; Kirillov, G A; Murugov, Vasilii M; Osin, Vladimir A; Sukharev, Stanislav A; Charukhchev, Aleksandr V

    2004-06-30

    An efficient reflecting coating made of a MIRO foil with an oxide layer is fabricated, which enhances the reflection of radiation of pump lamps in the head of a high-power neodymium laser and allows a gain g{sub 0}=5x10{sup -2} cm{sup -1} to be achieved. (lasers)

  1. INSIGHTS GAINED AS A RESULT OF A HIGH SCHOOL SOCIAL STUDIES COURSE.

    ERIC Educational Resources Information Center

    LALOR, IDA B.

    A STUDY ATTEMPTED TO DETERMINE WHETHER HIGH SCHOOL STUDENTS WHO HAVE GAINED KNOWLEDGE AND UNDERSTANDING OF CONCEPTS IN ANTHROPOLOGY WOULD--(1) ACHIEVE GREATER SELF-INSIGHT, (2) BECOME LESS ETHNOCENTRIC IN THEIR ATTITUDES TOWARD OTHERS, AND (3) INCREASE THEIR ABILITY TO THINK CRITICALLY ABOUT SOCIAL PROBLEMS. A 1-YEAR EXPERIMENTAL COURSE ON WORLD…

  2. High Stakes Testing and Student Achievement.

    ERIC Educational Resources Information Center

    Ediger, Marlow

    The effects of high stakes testing may be critical in the lives of public school students and may have many consequences for schools and teachers. There are no easy answers in measuring student achievement and in holding teachers accountable for learner progress. High stakes testing also involves responsibilities on the part of the principal who…

  3. Student Perceptions of High-Achieving Classmates

    ERIC Educational Resources Information Center

    Händel, Marion; Vialle, Wilma; Ziegler, Albert

    2013-01-01

    The reported study investigated students' perceptions of their high-performing classmates in terms of intelligence, social skills, and conscientiousness in different school subjects. The school subjects for study were examined with regard to cognitive, physical, and gender-specific issues. The results show that high academic achievements in…

  4. Shock ignition: a new approach to high gain inertial confinement fusion on the national ignition facility.

    PubMed

    Perkins, L J; Betti, R; LaFortune, K N; Williams, W H

    2009-07-24

    Shock ignition, an alternative concept for igniting thermonuclear fuel, is explored as a new approach to high gain, inertial confinement fusion targets for the National Ignition Facility (NIF). Results indicate thermonuclear yields of approximately 120-250 MJ may be possible with laser drive energies of 1-1.6 MJ, while gains of approximately 50 may still be achievable at only approximately 0.2 MJ drive energy. The scaling of NIF energy gain with laser energy is found to be G approximately 126E (MJ);{0.510}. This offers the potential for high-gain targets that may lead to smaller, more economic fusion power reactors and a cheaper fusion energy development path. PMID:19659364

  5. Expecting and Achieving Gains in Student Performance: EVAAS Value-Added Report 2002-2004 for the Archdiocese of Indianapolis

    ERIC Educational Resources Information Center

    Costello, Ronald W.; Shuey, Barbara

    2005-01-01

    The Archdiocese of Indianapolis has been using the Sander's value-added model to determine if they have had gains in student achievement in language arts, mathematics and reading. The article summarizes the method to make this determination and the results from three years of testing using the CTB McGraw-Hill Terre Nova test. The archdiocese has…

  6. The Relationship between Teacher-Licensure Level and Gains in the Student Academic Achievement in New Mexico Public Schools

    ERIC Educational Resources Information Center

    Morris, Roxann Lynne

    2010-01-01

    Purpose, scope, and method of study: The primary purpose of this study was to examine the relationship between teacher-licensure level in the New Mexico Three Tiered Licensure (NM 3-TL) System and gains in student academic achievement in reading and mathematics in grades four and five. A secondary purpose was to determine whether student…

  7. High Achievers: 23rd Annual Survey. Attitudes and Opinions from the Nation's High Achieving Teens.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Northbrook, IL.

    This report presents data from an annual survey of high school student leaders and high achievers. It is noted that of the nearly 700,000 high achievers featured in this edition, 5,000 students were sent the survey and 2,092 questionnaires were completed. Subjects were high school juniors and seniors selected for recognition by their principals or…

  8. Long lifetime, high density single-crystal erbium compound nanowires as a high optical gain material

    NASA Astrophysics Data System (ADS)

    Yin, Leijun; Ning, Hao; Turkdogan, Sunay; Liu, Zhicheng; Nichols, Patricia L.; Ning, C. Z.

    2012-06-01

    Erbium-containing materials of long lifetime and high Er density are important for achieving strong luminescence and high optical gain in compact integrated photonics devices. We have systematically studied the lifetime and crystal quality as a function of growth conditions for an erbium compound that we recently reported, erbium chloride silicate (ECS). The lifetime for the best quality ECS nanowires can be as long as 540 μs, the longest for high-density Er-materials, representing a lifetime-density product as high as 8.7 × 1018 s cm-3. Such high density, long lifetime erbium materials can find many interesting applications such as compact lasers or amplifiers.

  9. Design issues for a laboratory high gain fusion facility

    SciTech Connect

    Hogan, W.J.

    1987-11-02

    In an inertial fusion laboratory high gain facility, experiments will be carried out with up to 1000 MJ of thermonuclear yield. The experiment area of such a facility will include many systems and structures that will have to operate successfully in the difficult environment created by the sudden large energy release. This paper estimates many of the nuclear effects that will occur, discusses the implied design issues and suggests possible solutions so that a useful experimental facility can be built. 4 figs.

  10. High gain preamplifier based on optical parametric amplification

    DOEpatents

    Jovanovic, Igor; Bonner, Randal A.

    2004-08-10

    A high-gain preamplifier based on optical parametric amplification. A first nonlinear crystal is operatively connected to a second nonlinear crystal. A first beam relay telescope is operatively connected to a second beam relay telescope, to the first nonlinear crystal, and to the second nonlinear crystal. A first harmonic beamsplitter is operatively connected to a second harmonic beamsplitter, to the first nonlinear crystal, to the second nonlinear crystal, to the first beam relay telescope, and to the second beam relay telescope.

  11. High-gain, high-bandwidth, rail-to-rail, constant-gm CMOS operational amplifier

    NASA Astrophysics Data System (ADS)

    Huang, Hong-Yi; Wang, Bo-Ruei

    2013-01-01

    This study presents a high-gain, high-bandwidth, constant-gm , rail-to-rail operational amplifier (op-amp). The constant transconductance is improved with a source-to-bulk bias control of an input pair. A source degeneration scheme is also adapted to the output stage for receiving wide input range without degradation of the gain. Additionally, several compensation schemes are employed to enhance the stability. A test chip is fabricated in a 0.18 µm complementary metal-oxide semiconductor process. The active area of the op-amp is 181 × 173 µm2 and it consumes a power of 2.41 mW at a supply voltage of 1.8 V. The op-amp achieves a dc gain of 94.3 dB and a bandwidth of 45 MHz when the output capacitive load is connected to an effective load of 42.5 pF. A class-AB output stage combining a slew rate (SR) boost circuit provides a sinking current of 6 mA and an SR of 17 V/µs.

  12. Exploring Gains in Reading and Mathematics Achievement among Regular and Exceptional Students Using Growth Curve Modeling

    ERIC Educational Resources Information Center

    Shin, Tacksoo; Davison, Mark L.; Long, Jeffrey D.; Chan, Chi-Keung; Heistad, David

    2013-01-01

    Using four-wave longitudinal reading and mathematics data (4th to 7th grades) from a large urban school district, growth curve modeling was used as a tool for examining three research questions: Are achievement gaps closing in reading and mathematics? What are the associations between prior-achievement and growth across the reading and mathematics…

  13. The Groove of Growth: How Early Gains in Math Ability Influence Adolescent Achievement

    ERIC Educational Resources Information Center

    Watts, Tyler W.; Duncan, Greg J.; Siegler, Robert S.; Davis-Kean, Pamela E.

    2014-01-01

    A number of studies, both small scale and of nationally-representative student samples, have reported substantial associations between school entry math ability and later elementary school achievement. However, questions remain regarding the persistence of the association between early growth in math ability and later math achievement due to the…

  14. High gain ytterbium doped Ge pedestal large pitch fiber

    NASA Astrophysics Data System (ADS)

    Gaida, Christian; Stutzki, Fabian; Jansen, Florian; Otto, Hans-Jürgen; Eidam, Tino; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2014-03-01

    Large mode area rod-type fibers have enabled amplification of ultra-short pulses to mJ pulse energy and MW peak powers. For very large mode field areas, fibers have to be designed as rigid rods with typical fiber lengths of around 1 m for efficient operation. A shorter fiber length can be desirable to reduce the packaging size of commercial systems and to decrease the impact of parasitic nonlinear effects for peakpower scaling. The fiber design presented here is based on a modified large-pitch fiber with an effectively higher ytterbium concentration in the fiber core. To achieve index matching the cladding index needs to be changed. In this contribution we propose to co-dope the passive host material with germanium to match both indices and to obtain a higher Yb-concentration within the active core. Compared to standard LPF, where the core index is reduced by co-doping the core with Flourine, the ytterbium doping concentration of this novel germanium-pedestal LPF is doubled. A detailed numerical and experimental investigation shows that with short fiber lengths <40cm is feasible to achieve output powers beyond 100W with 10W seed. Significantly higher gains, of nearly 30 dB, can be achieved for fiber lengths in the order of 60cm. A similar gain can be expected in a conventional LPF with 1.20 m length. In conclusion, we demonstrate a fiber design for significantly enhanced energy storage per fiber length and improved pump absorption. This concept will notably reduce the footprint of ultra-short fiber laser systems.

  15. Achieving High Performance Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Yang, Yang

    2015-03-01

    Recently, metal halide perovskite based solar cell with the characteristics of rather low raw materials cost, great potential for simple process and scalable production, and extreme high power conversion efficiency (PCE), have been highlighted as one of the most competitive technologies for next generation thin film photovoltaic (PV). In UCLA, we have realized an efficient pathway to achieve high performance pervoskite solar cells, where the findings are beneficial to this unique materials/devices system. Our recent progress lies in perovskite film formation, defect passivation, transport materials design, interface engineering with respect to high performance solar cell, as well as the exploration of its applications beyond photovoltaics. These achievements include: 1) development of vapor assisted solution process (VASP) and moisture assisted solution process, which produces perovskite film with improved conformity, high crystallinity, reduced recombination rate, and the resulting high performance; 2) examination of the defects property of perovskite materials, and demonstration of a self-induced passivation approach to reduce carrier recombination; 3) interface engineering based on design of the carrier transport materials and the electrodes, in combination with high quality perovskite film, which delivers 15 ~ 20% PCEs; 4) a novel integration of bulk heterojunction to perovskite solar cell to achieve better light harvest; 5) fabrication of inverted solar cell device with high efficiency and flexibility and 6) exploration the application of perovskite materials to photodetector. Further development in film, device architecture, and interfaces will lead to continuous improved perovskite solar cells and other organic-inorganic hybrid optoelectronics.

  16. Polarization-insensitive optical gain characteristics of highly stacked InAs/GaAs quantum dots

    SciTech Connect

    Kita, Takashi; Suwa, Masaya; Kaizu, Toshiyuki; Harada, Yukihiro

    2014-06-21

    The polarized optical gain characteristics of highly stacked InAs/GaAs quantum dots (QDs) with a thin spacer layer fabricated on an n{sup +}-GaAs (001) substrate were studied in the sub-threshold gain region. Using a 4.0-nm-thick spacer layer, we realized an electronically coupled QD superlattice structure along the stacking direction, which enabled the enhancement of the optical gain of the [001] transverse-magnetic (TM) polarization component. We systematically studied the polarized electroluminescence properties of laser devices containing 30 and 40 stacked InAs/GaAs QDs. The net modal gain was analyzed using the Hakki-Paoli method. Owing to the in-plane shape anisotropy of QDs, the polarization sensitivity of the gain depends on the waveguide direction. The gain showing polarization isotropy between the TM and transverse-electric polarization components is high for the [110] waveguide structure, which occurs for higher amounts of stacked QDs. Conversely, the isotropy of the [−110] waveguide is easily achieved even if the stacking is relatively low, although the gain is small.

  17. Reliability achievement in high technology space systems

    NASA Technical Reports Server (NTRS)

    Lindstrom, D. L.

    1981-01-01

    The production of failure-free hardware is discussed. The elements required to achieve such hardware are: technical expertise to design, analyze, and fully understand the design; use of high reliability parts and materials control in the manufacturing process; and testing to understand the system and weed out defects. The durability of the Hughes family of satellites is highlighted.

  18. Some Correlates of Net Gain Resultant from Answer Changing on Objective Achievement Test Items

    ERIC Educational Resources Information Center

    Mueller, Daniel J.; Schwedel, Allan

    1975-01-01

    Determines the relationship of sex, answer-changing incidence, and total score to net changes in total score resulting from changing answers, by examining the answer-changing behavior of graduate students responding to achievement test items. (Author/RC)

  19. Development of high gain avalanche photodiodes for UV imaging applications

    NASA Astrophysics Data System (ADS)

    Sood, Ashok K.; Zeller, John W.; Welser, Roger E.; Puri, Yash R.; Dupuis, Russell D.; Ji, Mi-Hee; Kim, Jeomoh; Detchprohm, Theeradetch; Dhar, Nibir K.; Lewis, Jay S.; Peters, Roy L.

    2015-08-01

    High-resolution imaging in ultraviolet (UV) bands has many applications in defense and commercial systems. The shortest wavelength is desired for increased spatial resolution, which allows for small pixels and large formats. The next frontier is to develop UV avalanche photodiode (UV-APD) arrays with high gain to demonstrate high-resolution imaging. We compare performance characteristics of front-illuminated Al0.05Ga0.95N UV-APDs grown on a free-standing (FS) GaN substrate and a GaN/sapphire template. UV-APDs grown on a FS-GaN substrate show lower dark current densities for all fabricated mesa sizes than similar UV-APDs grown on a GaN/sapphire template. In addition, stable avalanche gain higher than 5×105 and a significant increase in the responsivity of UV-APDs grown on a FS-GaN substrate are observed as a result of avalanche multiplication at high reverse bias. We believe that the high crystalline quality of Al0.05Ga0.95N UVAPDs grown on a FS-GaN substrate with low dislocation density is responsible for the observed improvement of low leakage currents, high performance photodetector characteristics, and reliability of the devices.

  20. Academic achievement in high functioning autistic individuals.

    PubMed

    Minshew, N J; Goldstein, G; Taylor, H G; Siegel, D J

    1994-04-01

    Academic achievement levels in 54 high functioning (IQ > 70) autistic subjects were compared with those of 41 normal controls, who did not differ significantly in age, IQ, gender, race, or SES from the autistic subjects. The measures of academic achievement used included portions of the Detroit Tests of Learning Aptitude-2, the Woodcock Reading Mastery Test, and the Kaufman Test of Educational Achievement. Based on prior neuropsychological findings, it was hypothesized that autistic subjects would not differ from controls on subtests assessing mechanical and procedural skills, but would differ on subtests measuring comprehension and interpretive skills. As predicted, the autistic subjects performed significantly less well than controls on comprehension tasks, but not on mechanical reading, spelling, and computational tasks. This pattern is at variance with the typical academic profile of individuals with disabilities in reading or spelling, but shares some features with the nonverbal learning disabilities. PMID:8021313

  1. Software reconfigurable highly flexible gain switched optical frequency comb source.

    PubMed

    Pascual, M Deseada Gutierrez; Zhou, Rui; Smyth, Frank; Anandarajah, Prince M; Barry, Liam P

    2015-09-01

    The authors present the performance and noise properties of a software reconfigurable, FSR and wavelength tunable gain switched optical frequency comb source. This source, based on the external injection of a temperature tuned Fabry-Pérot laser diode, offers quasi-continuous wavelength tunability over the C-band (30nm) and FSR tunability ranging from 6 to 14GHz. The results achieved demonstrate the excellent spectral quality of the comb tones (RIN ~-130dB/Hz and low phase noise of 300kHz) and its outstanding stability (with fluctuations of the individual comb tones of less than 0.5dB in power and 5pm in wavelength, characterized over 24hours) highlighting its suitability for employment in next generation flexible optical transmission networks. PMID:26368425

  2. Development of low read noise high conversion gain CMOS image sensor for photon counting level imaging

    NASA Astrophysics Data System (ADS)

    Seo, Min-Woong; Kawahito, Shoji; Kagawa, Keiichiro; Yasutomi, Keita

    2016-05-01

    A CMOS image sensor with deep sub-electron read noise and high pixel conversion gain has been developed. Its performance is recognized through image outputs from an area image sensor, confirming the capability of photoelectroncounting- level imaging. To achieve high conversion gain, the proposed pixel has special structures to reduce the parasitic capacitances around FD node. As a result, the pixel conversion gain is increased due to the optimized FD node capacitance, and the noise performance is also improved by removing two noise sources from power supply. For the first time, high contrast images from the reset-gate-less CMOS image sensor, with less than 0.3e- rms noise level, have been generated at an extremely low light level of a few electrons per pixel. In addition, the photon-counting capability of the developed CMOS imager is demonstrated by a measurement, photoelectron-counting histogram (PCH).

  3. Pedagogical Content Beliefs about Reading Instruction and Their Relation to Gains in Student Achievement

    ERIC Educational Resources Information Center

    Behrmann, Lars; Souvignier, Elmar

    2013-01-01

    Teachers' pedagogical content beliefs about reading instruction are likely to predict progress in student achievement. Thus, in this study, 15 pre-service teachers gave reading promotion to low-performing sixth- and seventh-graders over a time period of 6 months. The pre-service teachers' pedagogical content beliefs were then related to…

  4. Prekindergarten Children's Executive Functioning Skills and Achievement Gains: The Utility of Direct Assessments and Teacher Ratings

    ERIC Educational Resources Information Center

    Fuhs, Mary Wagner; Farran, Dale Clark; Nesbitt, Kimberly Turner

    2015-01-01

    An accumulating body of evidence suggests that young children who exhibit greater executive functioning (EF) skills in early childhood also achieve more academically. The goal of the present study was to examine the unique contributions of direct assessments and teacher ratings of children's EF skills at the beginning of prekindergarten (pre-k) to…

  5. Achievement Gains and Staff Perception of School Climate. Research Brief. Volume 0707

    ERIC Educational Resources Information Center

    Morris, Don

    2008-01-01

    The importance of the beliefs and attitudes of teachers and building-level administrators in achieving school reform has come to be widely acknowledged. As University of Wisconsin professor Kent Peterson put it: "You can implement a good-quality improvement plan and knowledgeable, data-driven decision making, but if the [staff] doesn't believe…

  6. A high gain antenna system for airborne satellite communication applications

    NASA Technical Reports Server (NTRS)

    Maritan, M.; Borgford, M.

    1990-01-01

    A high gain antenna for commercial aviation satellites communication is discussed. Electromagnetic and practical design considerations as well as candidate systems implementation are presented. An evaluation of these implementation schemes is given, resulting in the selection of a simple top mounted aerodynamic phased array antenna with a remotely located beam steering unit. This concept has been developed into a popular product known as the Canadian Marconi Company CMA-2100. A description of the technical details is followed by a summary of results from the first production antennas.

  7. STARS A Two Stage High Gain Harmonic Generation FEL Demonstrator

    SciTech Connect

    M. Abo-Bakr; W. Anders; J. Bahrdt; P. Budz; K.B. Buerkmann-Gehrlein; O. Dressler; H.A. Duerr; V. Duerr; W. Eberhardt; S. Eisebitt; J. Feikes; R. Follath; A. Gaupp; R. Goergen; K. Goldammer; S.C. Hessler; K. Holldack; E. Jaeschke; Thorsten Kamps; S. Klauke; J. Knobloch; O. Kugeler; B.C. Kuske; P. Kuske; A. Meseck; R. Mitzner; R. Mueller; M. Neeb; A. Neumann; K. Ott; D. Pfluckhahn; T. Quast; M. Scheer; Th. Schroeter; M. Schuster; F. Senf; G. Wuestefeld; D. Kramer; Frank Marhauser

    2007-08-01

    BESSY is proposing a demonstration facility, called STARS, for a two-stage high-gain harmonic generation free electron laser (HGHG FEL). STARS is planned for lasing in the wavelength range 40 to 70 nm, requiring a beam energy of 325 MeV. The facility consists of a normal conducting gun, three superconducting TESLA-type acceleration modules modified for CW operation, a single stage bunch compressor and finally a two-stage HGHG cascaded FEL. This paper describes the faciliy layout and the rationale behind the operation parameters.

  8. Undulator interruption in high-gain free electron lasers

    SciTech Connect

    Kim, K.J.

    1997-10-01

    The effect of interrupting an undulator on the performance of high-gain free-electron lasers (FELs) is evaluated by analyzing 1-D Maxwell-Vlasov equations. It is found that the effect is small for a reasonable length of the interruptions for FEL parameters envisaged for short wavelength self-amplified spontaneous emission (SASE). Since the interruptions provide valuable space for quadrupoles and diagnostics, and at the same time permit a greater flexibility in mechanical design, the result of this paper is encouraging for construction of long undulator magnets required for SASE.

  9. Where do we stand with high gain FEL simulations?

    NASA Astrophysics Data System (ADS)

    Travish, Gil

    1997-06-01

    Computer technology improvements have allowed for more complete and detailed free electron laser simulations, yet the demands of the large number of new experiments and proposed projects has outpaced the capability and availability of present codes. This paper, based on a talk given at the conference of these proceedings, presents a brief assessment of Free Electron Laser (FEL) codes, their availability and features, as well as some opinions on what direction the FEL code community should take for the near future. The discussion of FEL codes is restricted here to ones for high gain amplifiers: no codes for oscillators, waveguides or exotic configurations are considered.

  10. High power VCSEL device with periodic gain active region

    NASA Astrophysics Data System (ADS)

    Ning, Y. Q., II; Qin, L.; Sun, Y. F.; Li, T.; Cui, J. J.; Peng, B.; Liu, G. Y.; Zhang, Y.; Liu, Y.; Wang, L. J.; Cui, D. F.; Xu, Z. Y.

    2007-11-01

    High power vertical cavity surface emitting lasers with large aperture have been fabricated through improving passivation, lateral oxidation and heat dissipation techniques. Different from conventional three quantum well structure, a periodic gain active region with nine quantum wells was incorporated into the VCSEL structure, with which high efficiency and high power operation were expected. The nine quantum wells were divided into three groups with each of them located at the antinodes of the cavity to enhance the coupling between the optical field and the gain region. Large aperture and bottom-emitting configuration was used to improve the beam quality and the heat dissipation. A maximum output power of 1.4W was demonstrated at CW operation for a 400μm-diameter device. The lasing wavelength shifted to 995.5nm with a FWHM of 2nm at a current of 4.8A due to the internal heating and the absence of active water cooling. A ring-shape farfield pattern was induced by the non-homogeneous lateral current distribution in large diameter device. The light intensity at the center of the ring increased with increasing current. A symmetric round light spot at the center and single transverse mode operation with a divergence angle of 16° were observed with current beyond 4.8A.

  11. Achieving high performance on the Intel Paragon

    SciTech Connect

    Greenberg, D.S.; Maccabe, B.; Riesen, R.; Wheat, S.; Womble, D.

    1993-11-01

    When presented with a new supercomputer most users will first ask {open_quotes}How much faster will my applications run?{close_quotes} and then add a fearful {open_quotes}How much effort will it take me to convert to the new machine?{close_quotes} This paper describes some lessons learned at Sandia while asking these questions about the new 1800+ node Intel Paragon. The authors conclude that the operating system is crucial to both achieving high performance and allowing easy conversion from previous parallel implementations to a new machine. Using the Sandia/UNM Operating System (SUNMOS) they were able to port a LU factorization of dense matrices from the nCUBE2 to the Paragon and achieve 92% scaled speed-up on 1024 nodes. Thus on a 44,000 by 44,000 matrix which had required over 10 hours on the previous machine, they completed in less than 1/2 hour at a rate of over 40 GFLOPS. Two keys to achieving such high performance were the small size of SUNMOS (less than 256 kbytes) and the ability to send large messages with very low overhead.

  12. Avoiding Obstructions in Aiming a High-Gain Antenna

    NASA Technical Reports Server (NTRS)

    Edmonds, Karina

    2006-01-01

    The High Gain Antenna Pointing and Obstruction Avoidance software performs computations for pointing a Mars Rover high-gain antenna for communication with Earth while (1) avoiding line-of-sight obstructions (the Martian terrain and other parts of the Rover) that would block communication and (2) taking account of limits in ranges of motion of antenna gimbals and of kinematic singularities in gimbal mechanisms. The software uses simplified geometric models of obstructions and of the trajectory of the Earth in the Martian sky(see figure). It treats all obstructions according to a generalized approach, computing and continually updating the time remaining before interception of each obstruction. In cases in which the gimbal-mechanism design allows two aiming solutions, the algorithm chooses the solution that provides the longest obstruction-free Earth-tracking time. If the communication session continues until an obstruction is encountered in the current pointing solution and the other solution is now unobstructed, then the algorithm automatically switches to the other position. This software also notifies communication- managing software to cease transmission during the switch to the unobstructed position, resuming it when the switch is complete.

  13. SIU-based modification in Kelley's measure of skewness to achieve gains in efficiency

    NASA Astrophysics Data System (ADS)

    Habibullah, Saleha Naghmi; Shan-E-Fatima, Syeda

    2015-02-01

    The importance of accurate modeling of life-lengths of components and systems cannot be over-emphasized. Some well-known distributions such as the Birnbaum Saunders distribution extensively used in Reliability Theory are known to fulfill the self-inversion property, the term `Self-Inverse at Unity' (`SIU') implying that, for a random variable X, the distribution of 1/ X is identical to the distribution of X. Very recently, it has been demonstrated the advantage that can be drawn from the SIU property by proposing a modification to the well-known formula of the empirical cumulative distribution function to obtain an estimator of the cumulative distribution function that is more efficient than the empirical cumulative distribution function in situations where the parent population can be assumed to be SIU. Subsequently, a number of papers have appeared proposing SIU-based modifications to the formulae of well-known estimators of central tendency, dispersion and kurtosis that are likely to yield gains in efficiency on account of an approach very similar to the one adopted for the modification of the formula of the empirical cumulative distribution function. In this paper, we propose SIU-based modification to Kelley's Measure of Skewness and, through a simulation study, demonstrate the potential of the proposed formula in improving the efficiency of the estimation process which, obviously, has important implications for accurate modeling of life-data encountered in various branches of engineering.

  14. Attitudes and Opinions from the Nation's High Achieving Teens. 18th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Educational Communications, Inc., Lake Forest, IL.

    This document contains factsheets and news releases which cite findings from a national survey of 1,985 high achieving high school students. Factsheets describe the Who's Who Among American High School Students recognition and service program for high school students and explain the Who's Who survey. A summary report of this eighteenth annual…

  15. The 'SuperFET' - A monolithic device for high-gain amplifiers

    NASA Astrophysics Data System (ADS)

    Crescenzi, E. J., Jr.; Wilser, W. T.; Oglesbee, R. W.; Algeri, S. J.

    1981-07-01

    The development of minimum area GaAs FET chips which resulted in ICs with two FETs on a single .7 sq mm chip linked with microstrip matching circuitry is described. Cost considerations are given, noting that the figure of merit was high due to matching elements covering over half of the total chip area. The gain for the X- and Ku-bands over discrete transistors were 6 and 5 dB, at 20 and 18 GHz respectively. Design objectives for the X-band IC of 7-12.5 GHz minimum bandwidth, multistage cascadability for amplifier gains in the 25 to 50 dB range, low VSWR gain flatness, and cost competitiveness with thin film discrete FETs were achieved. The Ku-band 'superFET' was designed for small size, application flexibility, and mechanical ruggedness and reliability, with an eye to EW military applications.

  16. 22nd Annual Survey of High Achievers: Attitudes and Opinions from the Nation's High Achieving Teens.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Northbrook, IL.

    This study surveyed high school students (N=1,879) who were student leaders or high achievers in the spring of 1991 for the purpose of determining their attitudes. Students were members of the junior or senior high school class during the 1990-91 academic year and were selected for recognition by their principals or guidance counselors, other…

  17. 21st Annual Survey of High Achievers: Attitudes and Opinions from the Nation's High Achieving Teens.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This survey was conducted by Who's Who Among American High School Students during the spring of 1990, to determine the attitudes of student leaders in U.S. high schools. A survey of high achievers sent to 5,000 students was completed and returned by approximately 2,000 students. All students were members of the junior or senior class during the…

  18. High gain antenna pointing on the Mars Exploration Rovers

    NASA Technical Reports Server (NTRS)

    Vanelli, C. Anthony; Ali, Khaled S.

    2005-01-01

    This paper describes the algorithm used to point the high gain antennae on NASA/JPL's Mars Exploration Rovers. The gimballed antennae must track the Earth as it moves across the Martian sky during communication sessions. The algorithm accounts for (1) gimbal range limitations, (2) obstructions both on the rover and in the surrounding environment, (3) kinematic singularities in the gimbal design, and (4) up to two joint-space solutions for a given pointing direction. The algorithm computes the intercept-times for each of the occlusions and chooses the jointspace solution that provides the longest track time before encountering an occlusion. Upon encountering an occlusion, the pointing algorithm automatically switches to the other joint-space solution if it is not also occluded. The algorithm has successfully provided flop-free pointing for both rovers throughout the mission.

  19. Low-dispersion, high-gain femtosecond optical pulse amplifier.

    PubMed

    Rodenberger, D C; Grossman, C H; Garito, A F

    1990-05-01

    We demonstrate a novel amplifier for femtosecond optical pulses. The output of a colliding-pulse mode-locked laser is amplified to 0.3 microJ per pulse at a repetition rate of 8 kHz by using 1 W of pump power from a copper-vapor laser. Our high-efficiency amplifier focuses the beam for four gain passes through a thin dye stream that uses a Z configuration with matched focusing. Because of low group-velocity dispersion, the output pulses are only slightly broadened, from 63 to 73 fsec, and may be used directly to generate a white-light continuum without pulse compression after amplification. PMID:19767988

  20. Undergraduates Achieve Learning Gains in Plant Genetics through Peer Teaching of Secondary Students

    ERIC Educational Resources Information Center

    Chrispeels, H. E.; Klosterman, M. L.; Martin, J. B.; Lundy, S. R.; Watkins, J. M.; Gibson, C. L.; Muday, G. K.

    2014-01-01

    This study tests the hypothesis that undergraduates who peer teach genetics will have greater understanding of genetic and molecular biology concepts as a result of their teaching experiences. Undergraduates enrolled in a non-majors biology course participated in a service-learning program in which they led middle school (MS) or high school (HS)…

  1. Teachers' Emotional Support Consistency Predicts Children's Achievement Gains and Social Skills

    ERIC Educational Resources Information Center

    Curby, Timothy W.; Brock, Laura L.; Hamre, Bridget K.

    2013-01-01

    Research Findings: It is widely acknowledged that consistent, high-quality teacher-student interactions promote optimal developmental outcomes for children. Previous research on the quality of teacher-student interactions provides empirical support for this premise. Little research has been conducted on the consistency of teacher-student…

  2. Black Phosphorus Mid-Infrared Photodetectors with High Gain

    NASA Astrophysics Data System (ADS)

    Guo, Qiushi; Pospischil, Andreas; Bhuiyan, Maruf; Jiang, Hao; Tian, He; Farmer, Damon; Deng, Bingchen; Li, Cheng; Han, Shu-Jen; Wang, Han; Xia, Qiangfei; Ma, Tso-Ping; Mueller, Thomas; Xia, Fengnian

    2016-07-01

    Recently, black phosphorus (BP) has joined the two dimensional material family as a promising candidate for photonic applications, due to its moderate bandgap, high carrier mobility, and compatibility with a diverse range of substrates. Photodetectors are probably the most explored BP photonic devices, however, their unique potential compared with other layered materials in the mid-infrared wavelength range has not been revealed. Here, we demonstrate BP mid infrared detectors at 3.39 um with high internal gain, resulting in an external responsivity of 82 A/W. Noise measurements show that such BP photodetectors are capable of sensing low intensity mid-infrared light in the picowatt range. Moreover, the high photoresponse remains effective at kilohertz modulation frequencies, because of the fast carrier dynamics arising from BPs moderate bandgap. The high photoresponse at mid infrared wavelengths and the large dynamic bandwidth, together with its unique polarization dependent response induced by low crystalline symmetry, can be coalesced to promise photonic applications such as chip-scale mid-infrared sensing and imaging at low light levels.

  3. Black Phosphorus Mid-Infrared Photodetectors with High Gain.

    PubMed

    Guo, Qiushi; Pospischil, Andreas; Bhuiyan, Maruf; Jiang, Hao; Tian, He; Farmer, Damon; Deng, Bingchen; Li, Cheng; Han, Shu-Jen; Wang, Han; Xia, Qiangfei; Ma, Tso-Ping; Mueller, Thomas; Xia, Fengnian

    2016-07-13

    Recently, black phosphorus (BP) has joined the two-dimensional material family as a promising candidate for photonic applications due to its moderate bandgap, high carrier mobility, and compatibility with a diverse range of substrates. Photodetectors are probably the most explored BP photonic devices, however, their unique potential compared with other layered materials in the mid-infrared wavelength range has not been revealed. Here, we demonstrate BP mid-infrared detectors at 3.39 μm with high internal gain, resulting in an external responsivity of 82 A/W. Noise measurements show that such BP photodetectors are capable of sensing mid-infrared light in the picowatt range. Moreover, the high photoresponse remains effective at kilohertz modulation frequencies, because of the fast carrier dynamics arising from BP's moderate bandgap. The high photoresponse at mid-infrared wavelengths and the large dynamic bandwidth, together with its unique polarization dependent response induced by low crystalline symmetry, can be coalesced to promise photonic applications such as chip-scale mid-infrared sensing and imaging at low light levels. PMID:27332146

  4. Interface Strategy To Achieve Tunable High Frequency Attenuation.

    PubMed

    Lv, Hualiang; Zhang, Haiqian; Ji, Guangbin; Xu, Zhichuan J

    2016-03-16

    Among all polarizations, the interface polarization effect is the most effective, especially at high frequency. The design of various ferrite/iron interfaces can significantly enhance the materials' dielectric loss ability at high frequency. This paper presents a simple method to generate ferrite/iron interfaces to enhance the microwave attenuation at high frequency. The ferrites were coated onto carbonyl iron and could be varied to ZnFe2O4, CoFe2O4, Fe3O4, and NiFe2O4. Due to the ferrite/iron interface inducing a stronger dielectric loss effect, all of these materials achieved broad effective frequency width at a coating layer as thin as 1.5 mm. In particular, an effective frequency width of 6.2 GHz could be gained from the Fe@NiFe2O4 composite. PMID:26918285

  5. Academic Attitudes of High Achieving and Low Achieving Academically Able Black Male Adolescents.

    ERIC Educational Resources Information Center

    Trotter, John Rhodes

    1981-01-01

    In order to identify the relationships between the attitudes and perceptions of peer pressure and the academic achievement of academically able male adolescents, this study compares the school attitudes of high achieving and low achieving Black male youth. (EF)

  6. High-Current Gain Two-Dimensional MoS₂-Base Hot-Electron Transistors.

    PubMed

    Torres, Carlos M; Lan, Yann-Wen; Zeng, Caifu; Chen, Jyun-Hong; Kou, Xufeng; Navabi, Aryan; Tang, Jianshi; Montazeri, Mohammad; Adleman, James R; Lerner, Mitchell B; Zhong, Yuan-Liang; Li, Lain-Jong; Chen, Chii-Dong; Wang, Kang L

    2015-12-01

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. PMID:26524388

  7. Attitudes and Opinions from the Nation's High Achieving Teens: 26th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    A national survey of 3,351 high achieving high school students (junior and senior level) was conducted. All students had A or B averages. Topics covered include lifestyles, political beliefs, violence and entertainment, education, cheating, school violence, sexual violence and date rape, peer pressure, popularity, suicide, drugs and alcohol,…

  8. Attitudes and Opinions from the Nation's High Achieving Teens. 24th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This survey represents information compiled by the largest national survey of adolescent leaders and high achievers. Of the 5,000 students selected demographically from "Who's Who Among American High School Students," 1,957 responded. All students surveyed had "A" or "B" averages, and 98% planned on attending college. Questions were asked about…

  9. High-Gain Avalanche Rushing amorphous Photoconductor (HARP) detector

    NASA Astrophysics Data System (ADS)

    Tanioka, K.

    2009-09-01

    We have been studying a very sensitive image sensor since the early 1980s. In 1985, the author found for the first time that an experimental pickup tube with an amorphous selenium photoconductive target exhibits high sensitivity with excellent picture quality because of a continuous and stable avalanche multiplication phenomenon. We named the pickup tube with an amorphous photoconductive layer operating in the avalanche-mode "HARP": High-gain Avalanche Rushing amorphous Photoconductor. A color camera equipped with the HARP pickup tubes has a maximum sensitivity of 11 lx at F8. This means that the HARP camera is about 100 times as sensitive as that of CCD camera for broadcasting. This ultrahigh-sensitivity HARP pickup tube is a powerful tool for reporting breaking news at night and other low-light conditions, the production of scientific programs, and numerous other applications, including medical diagnoses, biotech research, and nighttime surveillance. In addition, since the HARP target can convert X-rays into electrons directly, it should be possible to exploit this capability to produce X-ray imaging devices with unparalleled levels of resolution and sensitivity.

  10. High-gain nonlinear observer for simple genetic regulation process

    NASA Astrophysics Data System (ADS)

    Torres, L. A.; Ibarra-Junquera, V.; Escalante-Minakata, P.; Rosu, H. C.

    2007-07-01

    High-gain nonlinear observers occur in the nonlinear automatic control theory and are in standard usage in chemical engineering processes. We apply such a type of analysis in the context of a very simple one-gene regulation circuit. In general, an observer combines an analytical differential-equation-based model with partial measurement of the system in order to estimate the non-measured state variables. We use one of the simplest observers, that of Gauthier et al., which is a copy of the original system plus a correction term which is easy to calculate. For the illustration of this procedure, we employ a biological model, recently adapted from Goodwin's old book by De Jong, in which one plays with the dynamics of the concentrations of the messenger RNA coding for a given protein, the protein itself, and a single metabolite. Using the observer instead of the metabolite, it is possible to rebuild the non-measured concentrations of the mRNA and the protein.

  11. Fast ignition integrated experiments and high-gain point design

    NASA Astrophysics Data System (ADS)

    Shiraga, H.; Nagatomo, H.; Theobald, W.; Solodov, A. A.; Tabak, M.

    2014-05-01

    Integrated fast ignition experiments were performed at ILE, Osaka, and LLE, Rochester, in which a nanosecond driver laser implodes a deuterated plastic shell in front of the tip of a hollow metal cone and an intense ultrashort-pulse laser is injected through the cone to heat the compressed plasma. Based on the initial successful results of fast electron heating of cone-in-shell targets, large-energy short-pulse laser beam lines were constructed and became operational: OMEGA-EP at Rochester and LFEX at Osaka. Neutron enhancement due to heating with a ˜kJ short-pulse laser has been demonstrated in the integrated experiments at Osaka and Rochester. The neutron yields are being analysed by comparing the experimental results with simulations. Details of the fast electron beam transport and the electron energy deposition in the imploded fuel plasma are complicated and further studies are imperative. The hydrodynamics of the implosion was studied including the interaction of the imploded core plasma with the cone tip. Theory and simulation studies are presented on the hydrodynamics of a high-gain target for a fast ignition point design.

  12. Fast ignition integrated experiments and high-gain point design

    SciTech Connect

    Shiraga, H.; Nagatomo, H.; Theobald, W.; Solodov, A. A.; Tabak, M.

    2014-04-17

    Here, integrated fast ignition experiments were performed at ILE, Osaka, and LLE, Rochester, in which a nanosecond driver laser implodes a deuterated plastic shell in front of the tip of a hollow metal cone and an intense ultrashort-pulse laser is injected through the cone to heat the compressed plasma. Based on the initial successful results of fast electron heating of cone-in-shell targets, large-energy short-pulse laser beam lines were constructed and became operational: OMEGA-EP at Rochester and LFEX at Osaka. Neutron enhancement due to heating with a ~kJ short-pulse laser has been demonstrated in the integrated experiments at Osaka and Rochester. The neutron yields are being analyzed by comparing the experimental results with simulations. Details of the fast electron beam transport and the electron energy deposition in the imploded fuel plasma are complicated and further studies are imperative. The hydrodynamics of the implosion was studied including the interaction of the imploded core plasma with the cone tip. Theory and simulation studies are presented on the hydrodynamics of a high-gain target for a fast ignition point design.

  13. High-gain reverse guide field free electron lasers

    SciTech Connect

    Tsui, K.H.

    1995-10-01

    Electron beam trajectories under circularly polarized external wigglers in free electron laser devices with axial guide fields are reconsidered by introducing the self-fields of the electron beam. The competition between the self-fields and the wiggler field plus the action of the guide field are not only responsible for the known positive guide field singularity, but also the new reverse guide field singularity. The physics of the new reverse field singularity relies on the fact that an azimuthal magnetic field uniform in {ital z} is able to generate steady-state helical beam orbits just as if it were a transverse wiggler. According to this theory, the handness of the circularly polarized microwave should depend on the guide field configuration. High-gain strong pump equations coupled to these trajectories are used to account for the Massachusetts Institute of Technology reverse guide field results [Phys. Rev. Lett. {bold 67}, 3082 (1991)]. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  14. Research on a novel high gain model for dispersive spectrographic systems

    NASA Astrophysics Data System (ADS)

    Cheng, Liang; Ye, Zi; Gong, Xingzhi; Yu, Feihong

    2008-03-01

    Traditional dispersive spectrographic systems usually base on slit imaging. The entrance slit can ensure a remarkable spectral resolution but a loss of system throughput and vice versa, thus this kind of instruments can't achieve Jacquinot advantage and Fellgett advantage simultaneously and statically. To derive a high gain model for the stationary dispersive systems with these two advantages, traditional single-slit and the multi-slit spectrographic systems were studied. A method for single channel spectrum abstraction in a multi-slit spectrographic system was derived. This method demonstrates that if each individual slit in a multi-slit system possesses a transformation form of orthogonal independent column codes, the spectrum of each individual slit can be abstracted from superposed spectrum, spectral resolution of equivalent single-slit system is obtained and the system achieves dual advantages. This high gain computational system model is applicable for almost all kinds of existing dispersive spectrographic systems. Furthermore individual coded slits can be integrated as a coded aperture to increase system's integration level and reduce off-axis aberration. Based on the derivation of theoretical model, two kinds of coding forms' mathematical models were studied. To verify the derived theory, a testing system with a specially designed flat-field holographic concave grating and a coded aperture of order 16 Hadamard matrix form was set up. The experiment indicated that although optical aberration and other system noise were involved, this high gain system model could still achieve a high spectral resolution of 0.4nm as single-slit system, while remarkable system etendue (8X) and SNR (4X) were also obtained, which proved the correctness of the theoretical derivation.

  15. High Involvement Mothers of High Achieving Children: Potential Theoretical Explanations

    ERIC Educational Resources Information Center

    Hunsaker, Scott L.

    2013-01-01

    In American society, parents who have high aspirations for the achievements of their children are often viewed by others in a negative light. Various pejoratives such as "pushy parent," "helicopter parent," "stage mother," and "soccer mom" are used in the common vernacular to describe these parents. Multiple…

  16. A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement

    SciTech Connect

    Zhou, Haijun; Yang, Wenhai; Li, Zhixiu; Li, Xuefeng; Zheng, Yaohui

    2014-01-15

    We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO{sub 4} laser at 1064 nm with coherent output. The measured shot noise of 50 μW laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearities for both DC and AC amplifications in the laser power range between 12.5 μW and 1.52 mW.

  17. High gain broadband amplification of ultraviolet pulses in optical parametric chirped pulse amplifier.

    PubMed

    Wnuk, Paweł; Stepanenko, Yuriy; Radzewicz, Czesław

    2010-04-12

    We report on a high gain amplification of broadband ultraviolet femtosecond pulses in an optical parametric chirped pulse amplifier. Broadband ultraviolet seed pulses were obtained by an achromatic frequency doubling of the output from a femtosecond Ti:Sapphire oscillator. Stretched seed pulses were amplified in a multipass parametric amplifier with a single BBO crystal pumped by a ns frequency quadrupled Nd:YAG laser. A noncollinear configuration was used for a broadband amplification. The total (after compression) amplification of 2.510(5) was achieved, with compressed pulse energy of 30 microJ and pulse duration of 24 fs. We found that the measured gain was limited by thermal effects induced by the absorption of the pump laser by color centers created in the BBO crystal. PMID:20588633

  18. Howling canceling for high gain speakerphone systems exploiting the loudspeaker redundancy

    NASA Astrophysics Data System (ADS)

    Zhang, Jingjing; Yin, Qinye; Mu, Pengcheng; Song, Tianheng; Wang, Wei; Wu, Junchao

    2011-10-01

    Howling of an audio amplifying system is annoying, which may occur when a closed-loop is formed for amplified signals. In this paper, we exploit the space diversity offered by the loudspeaker redundancy and develop a new howling canceling approach for high gain speakerphone systems. The amplified waves are weighted at the two loudspeakers to achieve self-cancellation at the microphone after the propagation. As a result, the echo waves can be completely eliminated at the microphone, which avoids any feedback that yields the howling. Results of simulation and hardware test show effectiveness of the method.

  19. Rectangular-bore, high-gain laser plasma tube

    NASA Technical Reports Server (NTRS)

    Mollo, R. A.

    1969-01-01

    Rectangular-bore tube improves population inversion obtained from upper and terminal laser states, resulting in a significant increase in unsaturated gain factor. Radial field produces efficient pumping of upper laser state. Narrow tube dimensions cause increased diffusion flow of neon is metastable states to tube walls.

  20. Factors Implicated in High Mathematics Achievement

    ERIC Educational Resources Information Center

    Forgasz, Helen J.; Hill, Janelle C.

    2013-01-01

    The most recent Program for International Student Assessment (PISA) (2009) mathematical literacy results provide evidence that in Western English-speaking countries, including Australia, the gender gap in achievement appears to be widening in favour of males. In the study reported in this article, the aim was to explore the effects of gender,…

  1. High Ability Readers and the Achievement Gap

    ERIC Educational Resources Information Center

    Hunsaker, Scott L.; Parke, Cynthia J.; Bramble, Joan G.

    2004-01-01

    To close the achievement gap, the "No Child Left Behind" law calls for all students to make appropriate yearly progress. This presumably means that progress is being made by capable readers at the same time progress is being made by struggling readers. However, there appear to be unintended effects of "No Child Left Behind" that may impede the…

  2. Doped Contacts for High-Longevity Optically Activated, High Gain GaAs Photoconductive Semiconductor Switches

    SciTech Connect

    MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; O'MALLEY,MARTIN W.; HELGESON,WESLEY D.; BROWN,DARWIN JAMES; HJALMARSON,HAROLD P.; BACA,ALBERT G.; THORNTON,R.L.; DONALDSON,R.D.

    1999-12-17

    The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to over 100 million pulses. This was achieved by improving the ohmic contacts through the incorporation of a doped layer that is very effective in the suppression of filament formation, alleviating current crowding. Damage-free operation is now possible with virtually infinite expected lifetime at much higher current levels than before. The inherent damage-free current capacity of the bulk GaAs itself depends on the thickness of the doped layers and is at least 100A for a dopant diffusion depth of 4pm. The contact metal has a different damage mechanism and the threshold for damage ({approx}40A) is not further improved beyond a dopant diffusion depth of about 2{micro}m. In a diffusion-doped contact switch, the switching performance is not degraded when contact metal erosion occurs, unlike a switch with conventional contacts. This paper will compare thermal diffusion and epitaxial growth as approaches to doping the contacts. These techniques will be contrasted in terms of the fabrication issues and device characteristics.

  3. Doped Contacts for High-Longevity Optically Activated, High Gain GaAs Photoconductive Semiconductor Switches

    SciTech Connect

    Baca, A.G.; Brown, D.J.; Donaldson, R.D.; Helgeson, W.D.; Hjalmarson, H.P.; Loubriel, G.M.; Mar, A.; O'Malley, M.W.; Thornton, R.L.; Zutavern, F.J.

    1999-08-05

    The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to over 50 million pulses. This was achieved by improving the ohmic contacts through the incorporation of a doped layer beneath the PCSS contacts which is very effective in the suppression of filament formation and alleviating current crowding to improve the longevity of PCSS. Virtually indefinite, damage-free operation is now possible at much higher current levels than before. The inherent damage-free current capacity of the switch depends on the thickness of the doped layers and is at least 100A for a dopant diffusion depth of 4pm. The contact metal has a different damage mechanism and the threshold for damage ({approximately}40A) is not further improved beyond a dopant diffusion depth of about 2{micro}m. In a diffusion-doped contact switch, the switching performance is not degraded when contact metal erosion occurs. This paper will compare thermal diffusion and epitaxial growth as approaches to doping the contacts. These techniques will be contrasted in terms of the fabrication issues and device characteristics.

  4. Longevity of optically activated, high gain GaAs photoconductive semiconductor switches

    SciTech Connect

    Loubriel, G.M.; Zutavern, F.J.; Mar, A.

    1997-08-01

    The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to well over 10 million pulses by reducing the density of carriers at the semiconductor to metal interface. This was achieved by reducing the density in the vertical and lateral directions. The first was achieved by varying the spatial distribution of the trigger light thereby widening the current filaments that are characteristic of the high gain switches. The authors reduced the carrier density in the vertical direction by using ion implantation. These results were obtained for currents of about 10 A, current duration of 3.5 ns, and switched voltage of {approximately}2 kV. At currents of {approximately}70 A, the switches last for 0.6 million pulses. In order to improve the performance at high currents new processes such as deep diffusion and epitaxial growth of contacts are being pursued. To guide this effort the authors measured a carrier density of 6 x 10{sup 18} electrons (or holes)/cm{sup 3} in filaments that carry a current of 5 A.

  5. Telescope considered as a very high gain antenna

    NASA Astrophysics Data System (ADS)

    Detaille, Michel; Houmault, Patrice

    1990-07-01

    A design concept for an optical-antenna telescope to be used in intersatellite communication (in the framework of the ESA SILEX project) is presented. The main technical requirements for a SILEX transmit-receive antennna telescope are reviewed, and a Cassegrain configuration based on a parabolic primary mirror, a hyperbolic secondary mirror, and a five-lense collimator (with baffles to limit stray light) is shown in diagrams and discussed in detail, with particular attention to local angular distortion and transmission-antenna gain. Results from tests on a breadboard version are presented in tables and graphs, including transmission of 92.6 percent at 820 nm, rms wavefront error less than lambda/28, optical gain 114.47 dB, backscattered energy 1.7 x 10 to the -6th at 838 nm, and stray-light intensity slightly above specification at sun aspect angles less than 4.5 deg.

  6. High gain fusion in a Staged Z-pinch

    NASA Astrophysics Data System (ADS)

    Ney, Paul; Rahman, Hafiz; Wessel, Frank; Presura, Radu

    2013-10-01

    The implosion of a Staged Z-pinch is simulated for the Sandia National Laboratories, ZR accelerator. The pinch is comprised of a silver (Ag) plasma shell, 3-mm outer radius, 0.01-cm thick, imploding onto a uniform fill (target) of deuterium-tritium (DT); the Z-R parameters are: 130 ns, 27 MA, 22 MJ; the 2-1/2 D, radiation-MHD code is MACH2. Magnetosonic shock waves generated during implosion propagate at different speeds in the liner and target, producing a shock front at the interface, and a conduction channel ahead of the liner. The interface remains stable even as the outer-surface of the liner is RT unstable. At peak compression target plasma hot spots trigger ignition with a fusion yield of 200 MJ and a net-energy gain approaching 10. The stability remains robust and the gain is unaffected for perturbations ranging from 2-5%.

  7. Enhancing speed of pinning synchronizability: low-degree nodes with high feedback gains

    NASA Astrophysics Data System (ADS)

    Zhou, Ming-Yang; Zhuo, Zhao; Liao, Hao; Fu, Zhong-Qian; Cai, Shi-Min

    2015-12-01

    Controlling complex networks is of paramount importance in science and engineering. Despite recent efforts to improve controllability and synchronous strength, little attention has been paid to the speed of pinning synchronizability (rate of convergence in pinning control) and the corresponding pinning node selection. To address this issue, we propose a hypothesis to restrict the control cost, then build a linear matrix inequality related to the speed of pinning controllability. By solving the inequality, we obtain both the speed of pinning controllability and optimal control strength (feedback gains in pinning control) for all nodes. Interestingly, some low-degree nodes are able to achieve large feedback gains, which suggests that they have high influence on controlling system. In addition, when choosing nodes with high feedback gains as pinning nodes, the controlling speed of real systems is remarkably enhanced compared to that of traditional large-degree and large-betweenness selections. Thus, the proposed approach provides a novel way to investigate the speed of pinning controllability and can evoke other effective heuristic pinning node selections for large-scale systems.

  8. Enhancing speed of pinning synchronizability: low-degree nodes with high feedback gains

    PubMed Central

    Zhou, Ming-Yang; Zhuo, Zhao; Liao, Hao; Fu, Zhong-Qian; Cai, Shi-Min

    2015-01-01

    Controlling complex networks is of paramount importance in science and engineering. Despite recent efforts to improve controllability and synchronous strength, little attention has been paid to the speed of pinning synchronizability (rate of convergence in pinning control) and the corresponding pinning node selection. To address this issue, we propose a hypothesis to restrict the control cost, then build a linear matrix inequality related to the speed of pinning controllability. By solving the inequality, we obtain both the speed of pinning controllability and optimal control strength (feedback gains in pinning control) for all nodes. Interestingly, some low-degree nodes are able to achieve large feedback gains, which suggests that they have high influence on controlling system. In addition, when choosing nodes with high feedback gains as pinning nodes, the controlling speed of real systems is remarkably enhanced compared to that of traditional large-degree and large-betweenness selections. Thus, the proposed approach provides a novel way to investigate the speed of pinning controllability and can evoke other effective heuristic pinning node selections for large-scale systems. PMID:26626045

  9. Enhancing speed of pinning synchronizability: low-degree nodes with high feedback gains.

    PubMed

    Zhou, Ming-Yang; Zhuo, Zhao; Liao, Hao; Fu, Zhong-Qian; Cai, Shi-Min

    2015-01-01

    Controlling complex networks is of paramount importance in science and engineering. Despite recent efforts to improve controllability and synchronous strength, little attention has been paid to the speed of pinning synchronizability (rate of convergence in pinning control) and the corresponding pinning node selection. To address this issue, we propose a hypothesis to restrict the control cost, then build a linear matrix inequality related to the speed of pinning controllability. By solving the inequality, we obtain both the speed of pinning controllability and optimal control strength (feedback gains in pinning control) for all nodes. Interestingly, some low-degree nodes are able to achieve large feedback gains, which suggests that they have high influence on controlling system. In addition, when choosing nodes with high feedback gains as pinning nodes, the controlling speed of real systems is remarkably enhanced compared to that of traditional large-degree and large-betweenness selections. Thus, the proposed approach provides a novel way to investigate the speed of pinning controllability and can evoke other effective heuristic pinning node selections for large-scale systems. PMID:26626045

  10. Urban Students Achieve When High Schools Implement Proven Practices. Research Brief

    ERIC Educational Resources Information Center

    Bottoms, Gene; Han, Lingling; Presson, Alice

    2006-01-01

    Students benefit from a year or more gain in student achievement when urban district and high school leaders commit to the implementation of the "High Schools That Work" ("HSTW") design. It is not enough to be a "HSTW" site--it is about taking effective actions to implement the design. Schools that do take action witness significant progress in…

  11. Longevity improvement of optically activated, high gain GaAs photoconductive semiconductor switches

    SciTech Connect

    MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; O'MALLEY,MARTIN W.; HELGESON,WESLEY D.; BROWN,DARWIN JAMES; HJALMARSON,HAROLD P.; BACA,ALBERT G.

    2000-03-02

    The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to over 100 million pulses at 23A, and over 100 pulses at 1kA. This is achieved by improving the ohmic contacts by doping the semi-insulating GaAs underneath the metal, and by achieving a more uniform distribution of contact wear across the entire switch by distributing the trigger light to form multiple filaments. This paper will compare various approaches to doping the contacts, including ion implantation, thermal diffusion, and epitaxial growth. The device characterization also includes examination of the filament behavior using open-shutter, infra-red imaging during high gain switching. These techniques provide information on the filament carrier densities as well as the influence that the different contact structures and trigger light distributions have on the distribution of the current in the devices. This information is guiding the continuing refinement of contact structures and geometries for further improvements in switch longevity.

  12. Developing high-power hybrid resonant gain-switched thulium fiber lasers.

    PubMed

    Yan, Shuo; Wang, Yao; Zhou, Yan; Yang, Nan; Li, Yue; Tang, Yulong; Xu, Jianqiu

    2015-10-01

    In this paper, we propose hybrid-pumped resonant gain-switched thulium fiber lasers to realize high-average-power and high-pulse-energy 2-μm laser emissions. Based on numerical simulation, laser dynamics (pulse peak power, pulse energy, pulse duration, etc.) of this kind of laser system are investigated in detail. By taking advantages of the 793 nm continuous wave pump and the 1900 nm pulsed pump, performance of the laser emission can be significantly improved, with the highest average power of 28 W, peak power of 3.5 kW, pulse energy of 281 μJ, and narrowest pulse duration of 92 ns, all of which can be further optimized through designing the cavity parameters and the pumping circumstance. Compared with the pump pulses, two times improvement in pulse energy and average power has been achieved. This hybrid resonant gain-switched system has an all-fiber configuration and high efficiency (low heat load), and can be steadily extended into the cladding pump scheme, thus paving a new way to realize high power (>100 W average power) and high pulse energy (>1 mJ) 2 μm thulium fiber lasers. PMID:26480083

  13. Low threshold photonic crystal laser based on a Rhodamine dye doped high gain polymer.

    PubMed

    Shi, Lan-Ting; Jin, Feng; Zheng, Mei-Ling; Dong, Xian-Zi; Chen, Wei-Qiang; Zhao, Zhen-Sheng; Duan, Xuan-Ming

    2016-02-21

    We demonstrate low threshold lasing oscillation in a photonic crystal (PhC) laser by using tert-butyl Rhodamine B (t-Bu-RhB) doped gain media. Lactonic t-Bu-RhB is synthesized to improve doping concentration in polymethylmethacrylate (PMMA) films, and then isomerized to the zwitterion form to achieve highly fluorescent gain medium. The t-Bu-RhB doped PMMA film is sandwiched by a pair of polystyrene colloidal crystals to construct a PhC resonating cavity. Single-mode laser oscillation at 592 nm is observed when the PhC resonating cavity is pumped by a Nd:YAG laser. The lasing threshold is 0.12 MW cm(-2) utilizing 6.9 wt% t-Bu-RhB doped PMMA films, which is only 1/60 of that with 3 wt% t-Bu-RhB doped PMMA films. The concentration-dependent lasing action is attributed to different gain factors of the t-Bu-RhB doped PMMA films. Furthermore, a spatially and spectrally coherent laser beam from the PhC resonating cavity is verified by exploring the far-field image and angular dependence of the lasing emission. The approach provides a facile and efficient strategy to reduce the lasing threshold for fabricating low threshold PhC lasers. PMID:26817423

  14. Achieving strategic surety for high consequence software

    SciTech Connect

    Pollock, G.M.

    1996-09-01

    A strategic surety roadmap for high consequence software systems under the High Integrity Software (HIS) Program at Sandia National Laboratories guides research in identifying methodologies to improve software surety. Selected research tracks within this roadmap are identified and described detailing current technology and outlining advancements to be pursued over the coming decade to reach HIS goals. The tracks discussed herein focus on Correctness by Design, and System Immunology{trademark}. Specific projects are discussed with greater detail given on projects involving Correct Specification via Visualization, Synthesis, & Analysis; Visualization of Abstract Objects; and Correct Implementation of Components.

  15. Norview High School: Leadership Fosters Achievment

    ERIC Educational Resources Information Center

    Principal Leadership, 2013

    2013-01-01

    Often little unsaid things demonstrate what is truly important in a school. When teachers have common planning time and all of the department chairs share a single space as they do at Norview High School in Norfolk, VA, the unmistakable message is that instructional collaboration and leadership are expected and valued. Norview, an urban,…

  16. Achieving High-Temperature Ferromagnetic Topological Insulator

    NASA Astrophysics Data System (ADS)

    Katmis, Ferhat

    Topological insulators (TIs) are insulating materials that display conducting surface states protected by time-reversal symmetry, wherein electron spins are locked to their momentum. This unique property opens new opportunities for creating next-generation electronic and spintronic devices, including TI-based quantum computation. Introducing ferromagnetic order into a TI system without compromising its distinctive quantum coherent features could lead to a realization of several predicted novel physical phenomena. In particular, achieving robust long-range magnetic order at the TI surface at specific locations without introducing spin scattering centers could open up new possibilities for devices. Here, we demonstrate topologically enhanced interface magnetism by coupling a ferromagnetic insulator (FMI) to a TI (Bi2Se3); this interfacial ferromagnetism persists up to room temperature, even though the FMI (EuS) is known to order ferromagnetically only at low temperatures (<17 K). The induced magnetism at the interface resulting from the large spin-orbit interaction and spin-momentum locking feature of the TI surface is found to greatly enhance the magnetic ordering (Curie) temperature of the TI/FMI bilayer system. Due to the short range nature of the ferromagnetic exchange interaction, the time-reversal symmetry is broken only near the surface of a TI, while leaving its bulk states unaffected. The topological magneto-electric response originating in such an engineered TI could allow for an efficient manipulation of the magnetization dynamics by an electric field, providing an energy efficient topological control mechanism for future spin-based technologies. Work supported by MIT MRSEC through the MRSEC Program of NSF under award number DMR-0819762, NSF Grant DMR-1207469, the ONR Grant N00014-13-1-0301, and the STC Center for Integrated Quantum Materials under NSF grant DMR-1231319.

  17. NUTRIENT REQUIREMENTS OF HIGH-LEAN GAIN SWINE AT A HIGH ENVIRONMENTAL TEMPERATURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High-lean gain swine initially averaging 85 kg were assigned to 96 individual pens and given one of six diets ranging in the ratio of Total Ileal Digestible (TID) Lysine:Metabolizable Energy (ME) of 1.23 to 2.28 g/MCal. Pigs and feed intake were weighed weekly and backfat was measured on two week i...

  18. Self-Concept and Achievement Motivation of High School Students

    ERIC Educational Resources Information Center

    Lawrence, A. S. Arul; Vimala, A.

    2013-01-01

    The present study "Self-concept and Achievement Motivation of High School Students" was investigated to find the relationship between Self-concept and Achievement Motivation of High School Students. Data for the study were collected using Self-concept Questionnaire developed by Raj Kumar Saraswath (1984) and Achievement Motive Test (ACMT)…

  19. High-gain AlGaAs/GaAs double heterojunction Darlington phototransistors for optical neural networks

    NASA Technical Reports Server (NTRS)

    Kim, Jae H. (Inventor); Lin, Steven H. (Inventor)

    1991-01-01

    High-gain MOCVD-grown (metal-organic chemical vapor deposition) AlGaAs/GaAs/AlGaAs n-p-n double heterojunction bipolar transistors (DHBTs) and Darlington phototransistor pairs are provided for use in optical neural networks and other optoelectronic integrated circuit applications. The reduced base doping level used results in effective blockage of Zn out-diffusion, enabling a current gain of 500, higher than most previously reported values for Zn-diffused-base DHBTs. Darlington phototransitor pairs of this material can achieve a current gain of over 6000, which satisfies the gain requirement for optical neural network designs, which advantageously may employ neurons comprising the Darlington phototransistor pairs in series with a light source.

  20. ASE suppression in high-gain solid-state amplifiers by a leak method

    NASA Astrophysics Data System (ADS)

    Zhang, Yongliang; Ye, Haixian; Li, Mingzhong; Zheng, Jiangang; Wei, Xiaofeng; Gao, Song; Deng, Qinghua; Jiang, Xinying; Yan, Xiongwei; Wang, Zhenguo

    2013-07-01

    A leak method was developed to suppress amplified spontaneous emission (ASE) in large-aperture high-gain solid-state amplifiers. The gain medium edges are processed into an arris. The ASE ray will undergo reflection several times at the arris surface when it propagates to the gain medium edges, and most of its power will leak out. This leak method was tested in an experiment, in which a piece of commonly used gain medium was processed for contrast. The maximal increase of the gain value was 5.26% with the maximal pump power.

  1. An S-band high gain relativistic klystron amplifier with high phase stability

    SciTech Connect

    Wu, Y.; Li, Z. H.; Xu, Z.; Ma, Q. S.; Xie, H. Q.

    2014-11-15

    For the purpose of coherent high power microwave combining, an S-band high gain relativistic klystron amplifier with high phase stability is presented and studied. By the aid of 3D particle-in-cell code and circuit simulation software, the mechanism of parasitic oscillation in the device is investigated. And the RF lossy material is adopted in the simulation and experiment to suppress the oscillation. The experimental results show that with an input RF power of 10 kW, a microwave pulse with power of 1.8 GW is generated with a gain of 52.6 dB. And the relative phase difference fluctuation between output microwave and input RF signal is less than ±10° in 90 ns.

  2. Scientific Temper among Academically High and Low Achieving Adolescent Girls

    ERIC Educational Resources Information Center

    Kour, Sunmeet

    2015-01-01

    The present study was undertaken to compare the scientific temper of high and low achieving adolescent girl students. Random sampling technique was used to draw the sample from various high schools of District Srinagar. The sample for the present study consisted of 120 school going adolescent girls (60 high and 60 low achievers). Data was…

  3. High gain durable anti-reflective coating with oblate voids

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Colson, Thomas E.; Gonsalves, Peter R.; Abrams, Ze'ev

    2016-06-28

    Disclosed herein are single layer transparent coatings with an anti-reflective property, a hydrophobic property, and that are highly abrasion resistant. The single layer transparent coatings contain a plurality of oblate voids. At least 1% of the oblate voids are open to a surface of the single layer transparent coatings.

  4. High-gain inverters based on WSe2 complementary field-effect transistors.

    PubMed

    Tosun, Mahmut; Chuang, Steven; Fang, Hui; Sachid, Angada B; Hettick, Mark; Lin, Yongjing; Zeng, Yuping; Javey, Ali

    2014-05-27

    In this work, the operation of n- and p-type field-effect transistors (FETs) on the same WSe2 flake is realized,and a complementary logic inverter is demonstrated. The p-FET is fabricated by contacting WSe2 with a high work function metal, Pt, which facilities hole injection at the source contact. The n-FET is realized by utilizing selective surface charge transfer doping with potassium to form degenerately doped n+ contacts for electron injection. An ON/OFF current ratio of >10(4) is achieved for both n- and p-FETs with similar ON current densities. A dc voltage gain of >12 is measured for the complementary WSe2 inverter. This work presents an important advance toward realization of complementary logic devices based on layered chalcogenide semiconductors for electronic applications. PMID:24684575

  5. NASA/Cousteau ocean bathymetry experiment. Remote bathymetry using high gain LANDSAT data

    NASA Technical Reports Server (NTRS)

    Polcyn, F. C.

    1976-01-01

    Satellite remote bathymetry was varified to 22 m depths where water clarity was defined by alpha = .058 1/m and bottom reflection, r(b), was 26%. High gain band 4 and band 5 CCT data from LANDSAT 1 was used for a test site in the Bahama Islands and near Florida. Near Florida where alpha = .11 1/m and r(b) = 20%, depths to 10 m were verified. Depth accuracies within 10% rms were achieved. Position accuracies within one LANDSAT pixel were obtained by reference to the Transit navigation satellites. The Calypso and the Beayondan, two ships, were at anchor on each of the seven days during LANDSAT 1 and 2 overpasses: LORAN C position information was used when the ships were underway making depth transects. Results are expected to be useful for updating charts showing shoals hazardous to navigation or in monitoring changes in nearshore topography.

  6. High gain photoconductive semiconductor switch having tailored doping profile zones

    SciTech Connect

    Baca, Albert G.; Loubriel, Guillermo M.; Mar, Alan; Zutavern, Fred J; Hjalmarson, Harold P.; Allerman, Andrew A.; Zipperian, Thomas E.; O'Malley, Martin W.; Helgeson, Wesley D.; Denison, Gary J.; Brown, Darwin J.; Sullivan, Charles T.; Hou, Hong Q.

    2001-01-01

    A photoconductive semiconductor switch with tailored doping profile zones beneath and extending laterally from the electrical contacts to the device. The zones are of sufficient depth and lateral extent to isolate the contacts from damage caused by the high current filaments that are created in the device when it is turned on. The zones may be formed by etching depressions into the substrate, then conducting epitaxial regrowth in the depressions with material of the desired doping profile. They may be formed by surface epitaxy. They may also be formed by deep diffusion processes. The zones act to reduce the energy density at the contacts by suppressing collective impact ionization and formation of filaments near the contact and by reducing current intensity at the contact through enhanced current spreading within the zones.

  7. Setting Educational Priorities: High Achievers Speak Out. White Paper.

    ERIC Educational Resources Information Center

    Dickeson, Robert C.

    Noting that high achieving Indiana high school students can provide important insights into the educational system in the state, this study examined the opinions of recipients of Ameritchieve recognition, National Merit finalists, African-American students who were National Achievement finalists, and national Hispanic Scholar finalists, all from…

  8. A Study of the Effects of Different Levels of Initial Diagnosis on Gains in Reading Achievement for Adults in a Community College.

    ERIC Educational Resources Information Center

    Livingston, Catherine Lucille

    This study sought to determine whether varying the levels of initial diagnosis was related to gains in reading achievement after a maximum period of ten weeks of instruction. The subjects were students enrolled part- or full-time at Parkland College, a public community college located in Champaign, Illinois. Students were assigned to one of three…

  9. In-circuit-measurement of parasitic elements in high gain high bandwidth low noise transimpedance amplifiers.

    PubMed

    Cochems, P; Kirk, A; Zimmermann, S

    2014-12-01

    Parasitic elements play an important role in the development of every high performance circuit. In the case of high gain, high bandwidth transimpedance amplifiers, the most important parasitic elements are parasitic capacitances at the input and in the feedback path, which significantly influence the stability, the frequency response, and the noise of the amplifier. As these parasitic capacitances range from a few picofarads down to only a few femtofarads, it is nearly impossible to measure them accurately using traditional LCR meters. Unfortunately, they also cannot be easily determined from the transfer function of the transimpedance amplifier, as it contains several overlapping effects and its measurement is only possible when the circuit is already stable. Therefore, we developed an in-circuit measurement method utilizing minimal modifications to the input stage in order to measure its parasitic capacitances directly and with unconditional stability. Furthermore, using the data acquired with this measurement technique, we both proposed a model for the complicated frequency response of high value thick film resistors as they are used in high gain transimpedance amplifiers and optimized our transimpedance amplifier design. PMID:25554310

  10. Design, development and testing of the x-ray timing explorer High Gain Antenna System

    NASA Technical Reports Server (NTRS)

    Lecha, Javier; Woods, Claudia; Phan, Minh

    1995-01-01

    The High Gain Antenna System (HGAS), consisting of two High Gain Antenna Deployment Systems (HGADS) and two Antenna Pointing Systems (APS), is used to position two High Gain Antennas (HGA) on the X-Ray Timing Explorer (XTE). A similar APS will be used on the upcoming Tropical Rainfall Measuring Mission (TRMM). Both XTE and TRMM are NASA in-house satellites. The salient features of the system include the two-axis gimbal and control electronics of the APS and the spring deployment and latch/release mechanisms of the HGADS. This paper describes some of the challenges faced in the design and testing of this system and their resolutions.

  11. High Gain Antenna Gimbal for the 2003-2004 Mars Exploration Rover Program

    NASA Technical Reports Server (NTRS)

    Sokol, Jeff; Krishnan, Satish; Ayari, Laoucet

    2004-01-01

    The High Gain Antenna Assemblies built for the 2003-2004 Mars Exploration Rover (MER) missions provide the primary communication link for the Rovers once they arrive on Mars. The High Gain Antenna Gimbal (HGAG) portion of the assembly is a two-axis gimbal that provides the structural support, pointing, and tracking for the High Gain Antenna (HGA). The MER mission requirements provided some unique design challenges for the HGAG. This paper describes all the major subsystems of the HGAG that were developed to meet these challenges, and the requirements that drove their design.

  12. Convergent Evolution towards High Net Carbon Gain Efficiency Contributes to the Shade Tolerance of Palms (Arecaceae)

    PubMed Central

    Ma, Ren-Yi; Zhang, Jiao-Lin; Cavaleri, Molly A.; Sterck, Frank; Strijk, Joeri S.; Cao, Kun-Fang

    2015-01-01

    Most palm species occur in the shaded lower strata of tropical rain forests, but how their traits relate to shade adaptation is poorly understood. We hypothesized that palms are adapted to the shade of their native habitats by convergent evolution towards high net carbon gain efficiency (CGEn), which is given by the maximum photosynthetic rate to dark respiration rate ratio. Leaf mass per area, maximum photosynthetic rate, dark respiration and N and P concentrations were measured in 80 palm species grown in a common garden, and combined with data of 30 palm species growing in their native habitats. Compared to other species from the global leaf economics data, dicotyledonous broad-leaved trees in tropical rainforest or other monocots in the global leaf economics data, palms possessed consistently higher CGEn, achieved by lowered dark respiration and fairly high foliar P concentration. Combined phylogenetic analyses of evolutionary signal and trait evolution revealed convergent evolution towards high CGEn in palms. We conclude that high CGEn is an evolutionary strategy that enables palms to better adapt to shady environments than coexisting dicot tree species, and may convey advantages in competing with them in the tropical forest understory. These findings provide important insights for understanding the evolution and ecology of palms, and for understanding plant shade adaptations of lower rainforest strata. Moreover, given the dominant role of palms in tropical forests, these findings are important for modelling carbon and nutrient cycling in tropical forest ecosystems. PMID:26461108

  13. Convergent Evolution towards High Net Carbon Gain Efficiency Contributes to the Shade Tolerance of Palms (Arecaceae).

    PubMed

    Ma, Ren-Yi; Zhang, Jiao-Lin; Cavaleri, Molly A; Sterck, Frank; Strijk, Joeri S; Cao, Kun-Fang

    2015-01-01

    Most palm species occur in the shaded lower strata of tropical rain forests, but how their traits relate to shade adaptation is poorly understood. We hypothesized that palms are adapted to the shade of their native habitats by convergent evolution towards high net carbon gain efficiency (CGEn), which is given by the maximum photosynthetic rate to dark respiration rate ratio. Leaf mass per area, maximum photosynthetic rate, dark respiration and N and P concentrations were measured in 80 palm species grown in a common garden, and combined with data of 30 palm species growing in their native habitats. Compared to other species from the global leaf economics data, dicotyledonous broad-leaved trees in tropical rainforest or other monocots in the global leaf economics data, palms possessed consistently higher CGEn, achieved by lowered dark respiration and fairly high foliar P concentration. Combined phylogenetic analyses of evolutionary signal and trait evolution revealed convergent evolution towards high CGEn in palms. We conclude that high CGEn is an evolutionary strategy that enables palms to better adapt to shady environments than coexisting dicot tree species, and may convey advantages in competing with them in the tropical forest understory. These findings provide important insights for understanding the evolution and ecology of palms, and for understanding plant shade adaptations of lower rainforest strata. Moreover, given the dominant role of palms in tropical forests, these findings are important for modelling carbon and nutrient cycling in tropical forest ecosystems. PMID:26461108

  14. Nanoparticle-assisted high photoconductive gain in polymer/fullerene matrix

    PubMed Central

    Chen, Hsiang-Yu; Lo, Michael K. F.; Yang, Guanwen; Monbouquette, Harold G.; Yang, Yang

    2014-01-01

    Polymer/inorganic nanocrystal composites1–10 offer an attractive means to combine the merits of organic and inorganic materials into novel electronic and photonic systems. However, many applications of these composites are limited by the solubility11 and distribution of nanocrystals (NCs) in polymer matrices. Here, a high photoconductive gain has been achieved by blending cadmium telluride (CdTe) nanoparticles (NPs) into a polymer/fullerene matrix followed by a solvent annealing12 process. The NP surface capping ligand, N-phenyl-N’-methyldithiocarbamate, renders the NPs highly soluble in the polymer blend thereby enabling high nanocrystal loadings. An external quantum efficiency (EQE) as high as ~8000% (at 350nm) is reached at −4.5V. Hole-dominant devices coupled with AFM images are studied to uncover the probable mechanism. We observe a higher concentration of CdTe NPs is located near the cathode/polymer interface. These NPs with trapped electrons assist hole injection into the polymer under reverse bias, which contributes to greater than 100% EQE. PMID:18772915

  15. Investing in Our Teachers: What Focus of Professional Development Leads to the Highest Student Gains in Mathematics Achievement?

    ERIC Educational Resources Information Center

    Salinas, Alejandra

    2010-01-01

    The purpose of this meta-analysis was to better understand the relationship between the substantive-content focus of professional development for inservice teachers of mathematics and their students' achievement. That professional development for teachers enhances student achievement has been well established by recent studies; however, those…

  16. Low-noise pseudomorphic dual-gate cascode HEMT's with extremely high gain

    NASA Astrophysics Data System (ADS)

    Wenger, J.; Narozny, P.; Daembkes, H.; Splettstoesser, J.; Werres, C.

    1992-02-01

    Quarter-micron InGaAs-GaAs dual-gate HEMTs connected as a cascode MMIC in a compact manner have been fabricated and investigated. The devices show a high output impedance and a very low feedback capacitance, resulting in a high-voltage gain factor gm/gd of 125 and a Cgs/Cgd ratio of 45. The current gain cutoff frequency fT is 45 GHz and the maximum stable gain is 23.5 dB at 10 GHz and 19 dB at 20 GHz. The pseudomorphic cascode HEMTs show a low-noise figure of 1.1 dB with an associated gain of 22 dB at 10 GHz, at 18 GHz the minimum noise figure is 1.9 dB with 16-dB gain.

  17. To kill a kangaroo: understanding the decision to pursue high-risk/high-gain resources

    PubMed Central

    Jones, James Holland; Bird, Rebecca Bliege; Bird, Douglas W.

    2013-01-01

    In this paper, we attempt to understand hunter–gatherer foraging decisions about prey that vary in both the mean and variance of energy return using an expected utility framework. We show that for skewed distributions of energetic returns, the standard linear variance discounting (LVD) model for risk-sensitive foraging can produce quite misleading results. In addition to creating difficulties for the LVD model, the skewed distributions characteristic of hunting returns create challenges for estimating probability distribution functions required for expected utility. We present a solution using a two-component finite mixture model for foraging returns. We then use detailed foraging returns data based on focal follows of individual hunters in Western Australia hunting for high-risk/high-gain (hill kangaroo) and relatively low-risk/low-gain (sand monitor) prey. Using probability densities for the two resources estimated from the mixture models, combined with theoretically sensible utility curves characterized by diminishing marginal utility for the highest returns, we find that the expected utility of the sand monitors greatly exceeds that of kangaroos despite the fact that the mean energy return for kangaroos is nearly twice as large as that for sand monitors. We conclude that the decision to hunt hill kangaroos does not arise simply as part of an energetic utility-maximization strategy and that additional social, political or symbolic benefits must accrue to hunters of this highly variable prey. PMID:23884091

  18. To kill a kangaroo: understanding the decision to pursue high-risk/high-gain resources.

    PubMed

    Jones, James Holland; Bird, Rebecca Bliege; Bird, Douglas W

    2013-09-22

    In this paper, we attempt to understand hunter-gatherer foraging decisions about prey that vary in both the mean and variance of energy return using an expected utility framework. We show that for skewed distributions of energetic returns, the standard linear variance discounting (LVD) model for risk-sensitive foraging can produce quite misleading results. In addition to creating difficulties for the LVD model, the skewed distributions characteristic of hunting returns create challenges for estimating probability distribution functions required for expected utility. We present a solution using a two-component finite mixture model for foraging returns. We then use detailed foraging returns data based on focal follows of individual hunters in Western Australia hunting for high-risk/high-gain (hill kangaroo) and relatively low-risk/low-gain (sand monitor) prey. Using probability densities for the two resources estimated from the mixture models, combined with theoretically sensible utility curves characterized by diminishing marginal utility for the highest returns, we find that the expected utility of the sand monitors greatly exceeds that of kangaroos despite the fact that the mean energy return for kangaroos is nearly twice as large as that for sand monitors. We conclude that the decision to hunt hill kangaroos does not arise simply as part of an energetic utility-maximization strategy and that additional social, political or symbolic benefits must accrue to hunters of this highly variable prey. PMID:23884091

  19. Test-Taking Strategies of High and Low Mathematics Achievers

    ERIC Educational Resources Information Center

    Hong, Eunsook; Sas, Maggie; Sas, John C.

    2006-01-01

    The authors explored test-preparation and test-taking strategies that high school students used in algebra tests. From a pool of high school students (N = 156), 61 students participated in interviews, and of those interviewed, 26 represented those who were high achieving as well as highly interested in mathematics (n = 15) vs. those who were low…

  20. A novel 4H-SiC lateral bipolar junction transistor structure with high voltage and high current gain

    NASA Astrophysics Data System (ADS)

    Deng, Yong-Hui; Xie, Gang; Wang, Tao; Sheng, Kuang

    2013-09-01

    In this paper, a novel structure of a 4H-SiC lateral bipolar junction transistor (LBJT) with a base field plate and double RESURF in the drift region is presented. Collector-base junction depletion extension in the base region is restricted by the base field plate. Thin base as well as low base doping of the LBJT therefore can be achieved under the condition of avalanche breakdown. Simulation results show that thin base of 0.32 μm and base doping of 3 × 1017 cm-3 are obtained, and corresponding current gain is as high as 247 with avalanche breakdown voltage of 3309 V when the drift region length is 30 μm. Besides, an investigation of a 4H-SiC vertical BJT (VBJT) with comparable breakdown voltage (3357 V) shows that the minimum base width of 0.25 μm and base doping as high as 8 × 1017 cm-3 contribute to a maximum current gain of only 128.

  1. Biculturalism and Academic Achievement of African American High School Students

    ERIC Educational Resources Information Center

    Rust, Jonathan P.; Jackson, Margo A.; Ponterotto, Joseph G.; Blumberg, Fran C.

    2011-01-01

    Biculturalism was examined as a factor that may positively affect the academic achievement of African American high school students, beyond cultural identity and self-esteem. Hierarchical regression analyses determined that cultural identity and academic self-esteem were important factors for academic achievement, but not biculturalism.…

  2. Tracking and Detracking: High Achievers in Massachusetts Middle Schools

    ERIC Educational Resources Information Center

    Loveless, Tom

    2009-01-01

    This study examines tracking--the practice of grouping students into separate classes or courses based on their prior academic achievement--at the middle-school level, and the percentage of high-achieving students in tracked and untracked schools. It focuses on Massachusetts, a leader in "reforming" tracking, and the changes that have…

  3. Mobility and Student Achievement in High Poverty Schools

    ERIC Educational Resources Information Center

    Dalton, Janet Denise

    2013-01-01

    Student mobility is an issue for high poverty schools in the shadow of increased rigor and accountability for student performance. Whereas mobility is not a sole cause for poor achievement, it is a contributing factor for students in poverty who are already considered to be at risk of low achievement. Student mobility creates a hardship for…

  4. Brightness and coherence of synchrotron radiation and high-gain free electron lasers

    SciTech Connect

    Kim, K.J.

    1986-10-01

    The characteristics of synchrotron radiation are reviewed with particular attention to its phase-space properties and coherence. The transition of the simple undulator radiation to more intense, more coherent high-gain free electron lasers, is discussed.

  5. Attitudes and Opinions from the Nation's High Achieving Teens: 29th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report presents the 1998 statistical findings of the annual survey to determine the attitudes of national high school student leaders. Questionnaires were completed by 3,123 high school juniors and seniors, all of whom were selected for recognition in "Who's Who among American High School Students." In addition to demographic information, the…

  6. Gain media edge treatment to suppress amplified spontaneous emission in a high power laser

    DOEpatents

    Hackel, Lloyd A.; Soules, Thomas F.; Fochs, Scott N.; Rotter, Mark D.; Letts, Stephan A.

    2008-12-09

    A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges using a substantially high index bonding elastomer or epoxy to a predetermined electromagnetic absorbing arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

  7. Brightness and coherence of radiation from undulators and high-gain free electron lasers

    SciTech Connect

    Kim, Kwang-Je

    1987-03-01

    The purpose of this paper is to review the radiation characteristics of undulators and high-gain free electron lasers (FELs). The topics covered are: a phase-space method in wave optics and synchrotron radiation, coherence from the phase-space point of view, discussions of undulator performances in next-generation synchrotron radiation facility and the characteristics of the high-gain FELs and their performances. (LSP)

  8. High-Gain AlxGa1-xAs/GaAs Transistors For Neural Networks

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Hoon; Lin, Steven H.

    1991-01-01

    High-gain AlxGa1-xAs/GaAs npn double heterojunction bipolar transistors developed for use as phototransistors in optoelectronic integrated circuits, especially in artificial neural networks. Transistors perform both photodetection and saturating-amplification functions of neurons. Good candidates for such application because structurally compatible with laser diodes and light-emitting diodes, detect light, and provide high current gain needed to compensate for losses in holographic optical elements.

  9. Associations of Future Expectations, Negative Friends, and Academic Achievement in High-Achieving African American Adolescents

    ERIC Educational Resources Information Center

    Cunningham, Michael; Corprew, Charles S., III; Becker, Jonathan E.

    2009-01-01

    The relations of future expectations (general and academic) to academic outcomes were examined in a sample of 129 African American high-achieving adolescents (majority female participants, n = 92). This study was interested in the multidimensional nature of future expectations. Results from the study confirm the hypothesis that academic future…

  10. The "Renaissance Child": High Achievement and Gender in Late Modernity

    ERIC Educational Resources Information Center

    Skelton, Christine; Francis, Becky

    2012-01-01

    This paper draws on the concept of the "Renaissance Child" to illustrate the ways in which gender influences the opportunities and possibilities of high-achieving pupils. Using data from a study of 12-13-year high-achieving boys and girls based in schools in England, the paper considers the ways in which a group of popular boys was able to show an…

  11. Ultra-long and high-stability random laser based on EDF gain-media and Rayleigh scattering distributed mirror

    NASA Astrophysics Data System (ADS)

    Aporta, I.; Quintela, M. A.; Rodríguez-Cobo, L.; López-Higuera, J. M.

    2015-09-01

    An ultra-long, low-threshold and high-stability Random distributed feedback fiber laser (RDF-FL) based on Erbium-doped fiber (EDF) to provide the gain medium, and single mode fiber (SMF) as a distributed mirror in combination with fiber-brag grating (FBG) to form the cavity is proposed in this paper. Typical random laser radiation for a SMF length of 50 km with a low-threshold of 10 dBm and high-stability (~0.1 dB) is achieved, thanks to the design of the cavity and the high-gain from the pumped erbium-doped fiber. Besides, 200 km quasi-losses random laser due to the distributed mirror and the FBG reflector is demonstrated.

  12. The Effects of Block Scheduling on High School Academic Achievement

    ERIC Educational Resources Information Center

    Lewis, Chance W.; Dugan, James J.; Winokur, Marc A.; Cobb, Brian R.

    2005-01-01

    The effect of block scheduling on high school student achievement in mathematics and reading was investigated in this study through the use of an ex post-facto, longitudinal research design. Specifically, student scores from 9th and 11th-grade standardized tests were matched and sorted by junior high and high school attended. Outcome measures…

  13. Attitudes and Opinions from the Nation's High Achieving Teens: 28th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report details the 28th annual study to examine the attitudes of student leaders in U.S. high schools. Participating in the survey were 3,210 adolescents, primarily 16- and 17-year-olds, who had been featured in the 1997 edition of "Who's Who Among American High School Students." The report presents demographic information on the survey…

  14. Attitudes and Opinions from the Nation's High Achieving Teens: 27th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report details the 27th annual study to examine the attitudes of student leaders in U.S. high schools. Participating in the survey were 3,370 adolescents, primarily 16- and 17-year-olds, who had been featured in the 1996 edition of "Who's Who Among American High School Students." The report presents demographic information on the survey…

  15. Wideband and flat-gain amplifier based on high concentration erbium-doped fibres in parallel double-pass configuration

    SciTech Connect

    Hamida, B A; Cheng, X S; Harun, S W; Naji, A W; Arof, H; Al-Khateeb, W; Khan, S; Ahmad, H

    2012-03-31

    A wideband and flat gain erbium-doped fibre amplifier (EDFA) is demonstrated using a hybrid gain medium of a zirconiabased erbium-doped fibre (Zr-EDF) and a high concentration erbium-doped fibre (EDF). The amplifier has two stages comprising a 2-m-long ZEDF and 9-m-long EDF optimised for C- and L-band operations, respectively, in a double-pass parallel configuration. A chirp fibre Bragg grating (CFBG) is used in both stages to ensure double propagation of the signal and thus to increase the attainable gain in both C- and L-band regions. At an input signal power of 0 dBm, a flat gain of 15 dB is achieved with a gain variation of less than 0.5 dB within a wide wavelength range from 1530 to 1605 nm. The corresponding noise figure varies from 6.2 to 10.8 dB within this wavelength region.

  16. High performance quantum cascade lasers: Loss, beam stability, and gain engineering

    NASA Astrophysics Data System (ADS)

    Bouzi, Pierre Michel

    Quantum Cascade (QC) lasers are semiconductor devices emitting in the mid-infrared (3-30 micron) and terahertz (30-300 micron) regions of the electromagnetic spectrum. Since their first demonstration by Jerome Faist et. al. in 1994, they have evolved very quickly into high performance devices and given rise to many applications such as trace-gas sensing, medical diagnosis, free-space communication, and light detection and ranging (LIDAR). In this thesis, we investigate a further increase of the performance of QC devices and, through meticulous device modeling and characterizations, gain a deeper understanding of several of their unique characteristics, especially their carrier transport and lifetime, their characteristic temperature, their waveguide loss and modal gain, their leakage current, and their transverse mode profile. First, in our quest to achieve higher performance, we investigate the effect of growth asymmetries on device transport characteristics. This investigation stems from recent studies on the role of interface roughness on intersubband scattering and device performance. Through a symmetric active core design, we find that interface roughness and ionized impurity scattering induced by dopant migration play a significant role in carrier transport through the device. Understanding how interface roughness affects intersubband scattering, in turn, we engineer the gain in QC devices by placing monolayer barriers at specific locations within the device band structure. These strategically placed additional thin barrier layers introduce roughness scattering into the device active region, thereby selectively decreasing the lower laser state lifetime and increasing population inversion necessary for laser action. Preliminary measurement results from modified devices reveal a 50% decrease in the emission broadening compared to the control structures, which should lead to a two-fold increase in gain. A special class of so-called "strong coupling" QC lasers

  17. Characterization of a high-gain Ne-like Fe transient x-ray laser

    SciTech Connect

    Dunn, J; Facnov, A; Fournier, K B; Moon, S J; Osterheld, A; Pikuz, T; Shlyaptsev, V N

    1999-09-13

    The authors present experimental results of a high efficiency Ne-like Fe transient collisional excitation x-ray laser using the COMET 15 TW table-top laser system at LLNL. The plasma formation, ionization and collision excitation of the x-ray laser have been optimized using two sequential laser pulses: a plasma formation beam with 5 J energy of 600 ps duration and a pump beam with 5 J energy of 1.2 ps duration. Since the observation of strong lasing on the 255 {angstrom} 3p-3s J = 0-1 transition of Ne-like Fe, they have achieved high gains of 35 cm{sup {minus}1} and saturation of the x-ray laser. A five-stage traveling wave excitation enhances the strongest Fe 3p-3s 255 {angstrom} lasing line as well as additional x-ray lines. A careful characterization of the plasma column conditions using L-shell spectroscopy indicates the degree of ionization along the line focus.

  18. A Study on the Relationship between Logical Thinking Level and the Achievement in Enrichment Physics of School Science High Achievers.

    ERIC Educational Resources Information Center

    Kim, Young-Min; Lee, Sung-Yi

    2001-01-01

    Investigates science high achievers' achievement in enrichment physics and logical thinking levels, and analyzes the relationship between logical thinking level and achievement in enrichment physics of high achievers in science. Involves (n=35) 7th and 8th grade junior high school students in the study. Uses the Group Assessment of Logical…

  19. Loop gain stabilizing with an all-digital automatic-gain-control method for high-precision fiber-optic gyroscope.

    PubMed

    Zheng, Yue; Zhang, Chunxi; Li, Lijing; Song, Lailiang; Chen, Wen

    2016-06-10

    For a fiber-optic gyroscope (FOG) using electronic dithers to suppress the dead zone, without a fixed loop gain, the deterministic compensation for the dither signals in the control loop of the FOG cannot remain accurate, resulting in the dither residuals in the FOG rotation rate output and the navigation errors in the inertial navigation system. An all-digital automatic-gain-control method for stabilizing the loop gain of the FOG is proposed. By using a perturbation square wave to measure the loop gain of the FOG and adding an automatic gain control loop in the conventional control loop of the FOG, we successfully obtain the actual loop gain and make the loop gain converge to the reference value. The experimental results show that in the case of 20% variation in the loop gain, the dither residuals are successfully eliminated and the standard deviation of the FOG sampling outputs is decreased from 2.00  deg/h to 0.62  deg/h (sampling period 2.5 ms, 10 points smoothing). With this method, the loop gain of the FOG can be stabilized over the operation temperature range and in the long-time application, which provides a solid foundation for the engineering applications of the high-precision FOG. PMID:27409016

  20. Milwaukee Independent Charter Schools Study: Report on Two- and Three-Year Achievement Gains. SCDP Milwaukee Evaluation. Report # 25

    ERIC Educational Resources Information Center

    Witte, John F.; Wolf, Patrick J.; Dean, Alicia; Carlson, Deven

    2011-01-01

    The general purpose of this study is to assess the effectiveness of Milwaukee's independent charter schools in promoting student achievement growth. Independent charter schools are authorized by non-school district entities and are considered "independent" because they are not a part of the Milwaukee Public School District (MPS). Specifically, the…

  1. Third Phase: Achievement Gains Associated with Implementation of the Assistant Teacher Program in the First Three Grades.

    ERIC Educational Resources Information Center

    Handley, Herbert M.

    The effectiveness of Mississippi's Assistant Teacher Program (ATP) was evaluated after its third year of operation, determining: (1) whether first graders who were exposed to teachers and assistant teachers who had been in ATP for three years continued to make progress in academic achievement; (2) the effectiveness of ATP in fostering achievement…

  2. Charter School Effects in an Urban School District: An Analysis of Student Achievement Gains in Indianapolis. Research Brief

    ERIC Educational Resources Information Center

    Nicotera, Anna; Mendiburo, Maria; Berends, Mark

    2010-01-01

    The current study aimed to reach a deeper understanding of the effects of charter schools by examining student achievement in one unique setting--Indianapolis. Although the charter school initiative in Indianapolis has received national recognition for its innovations, entrepreneurial leaders, and capacity to build local support (Skinner, 2007),…

  3. Calculation of the gain coefficient in cryogenically cooled Yb : YAG disks at high heat generation rates

    SciTech Connect

    Vadimova, O L; Mukhin, I B; Kuznetsov, I I; Palashov, O V; Perevezentsev, E A; Khazanov, Efim A

    2013-03-31

    We have calculated the stored energy and gain coefficient in disk gain elements cooled to cryogenic temperatures. The problem has been solved with allowance for intense heat generation, amplified spontaneous emission and parasitic lasing, without averaging over any spatial coordinate. The numerical simulation results agree well with experimental data, in particular at high heat generation rates. Experimental data and theoretical analysis indicate that composite disk gain elements containing an undoped region can store considerably more energy due to suppression of amplified spontaneous emission and parasitic lasing. (extreme light fields and their applications)

  4. Performance studies of high gain photomultiplier having Z-configuration of microchannel plates

    NASA Astrophysics Data System (ADS)

    Lo, C. C.; Leskovar, B.

    1980-11-01

    The characteristics of a high gain type ITT F4129 photomultiplier having three microchannel plates in cascade for electron multiplications were investigated. These plates are in the Z-configuration. Measurements are given of the gain dark current, cathode quantum efficiency, anode pulse linearity, electron transit time, single and multiphoton time spreads, fatigue, and pulse height resolution. The gain as a function of transverse magnetic field was measured and discussed. Photomultiplier characteristics as a function of the input pulse repetition frequency were also investigated and discussed.

  5. DEMONSTRATION OF 3D EFFECTS WITH HIGH GAIN AND EFFICIENCY IN A UV FEL OSCILLATOR

    SciTech Connect

    Stephen Benson; George Biallas; Keith Blackburn; James Boyce; Donald Bullard; James Coleman; Cody Dickover; David Douglas; Forrest Ellingsworth; Pavel Evtushenko; Carlos Hernandez-Garcia; Christopher Gould; Joseph Gubeli; David Hardy; Kevin Jordan; John Klopf; James Kortze; Robert Legg; Matthew Marchlik; Steven Moore; George Neil; Thomas Powers; Daniel Sexton; Michelle D. Shinn; Christopher Tennant; Richard Walker; Anne Watson; Gwyn Williams; Frederick Wilson; Shukui Zhang

    2011-03-01

    We report on the performance of a high gain UV FEL oscillator operating on an energy recovery linac at Jefferson Lab. The high brightness of the electron beam leads to both gain and efficiency that cannot be reconciled with a one-dimensional model. Three-dimensional simulations do predict the performance with reasonable precision. Gain in excess of 100% per pass and an efficiency close to 1/2NW, where NW is the number of wiggler periods, is seen. The laser mirror tuning curves currently permit operation in the wavelength range of 438 to 362 nm. Another mirror set allows operation at longer wavelengths in the red with even higher gain and efficiency.

  6. Student Achievement for Whom? High-Performing and Still "Playing the Game," the Meaning of School Achievement among High Achieving African American Students

    ERIC Educational Resources Information Center

    Wiggan, Greg

    2014-01-01

    The preponderance of the research on African American students has generally focused on issues of school failure and underperformance. While the literature on high achieving Black students is sparse, very little is known about these students' school experiences and the meanings that they assign to achievement. Using student-based inquiry…

  7. Attitudes and Opinions from the Nation's High Achieving Teens. 25th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This survey was conducted during the spring of 1994 for the purpose of determining the attitudes of student leaders in the nation's high schools. Eight thousand surveys were sent out to students, of which 3177 were returned. All students surveyed were members of the junior or senior class during the 1993-94 academic year. They were selected for…

  8. Entanglement, EPR correlations, and mesoscopic quantum superposition by the high-gain quantum injected parametric amplification

    SciTech Connect

    Caminati, Marco; De Martini, Francesco; Perris, Riccardo; Secondi, Veronica; Sciarrino, Fabio

    2006-12-15

    We investigate the multiparticle quantum superposition and the persistence of bipartite entanglement of the output field generated by the quantum injected high-gain optical parametric amplification of a single photon. The physical configuration based on the optimal universal quantum cloning has been adopted to investigate how the entanglement and the quantum coherence of the system persists for large values of the nonlinear parametric gain g.

  9. Brain Hemisphericity and Mathematics Achievement of High School Students

    ERIC Educational Resources Information Center

    Fernandez, Sanny F.

    2011-01-01

    This study aimed to find out the brain hemisphericity and mathematics achievement of high school students. The respondents of the study were the 168 first year high school students of Colegio de San Jose, during school year 2010-2011 who were chosen through stratified random sampling. The descriptive and interview methods of research were used in…

  10. Exploring High-Achieving Students' Images of Mathematicians

    ERIC Educational Resources Information Center

    Aguilar, Mario Sánchez; Rosas, Alejandro; Zavaleta, Juan Gabriel Molina; Romo-Vázquez, Avenilde

    2016-01-01

    The aim of this study is to describe the images that a group of high-achieving Mexican students hold of mathematicians. For this investigation, we used a research method based on the Draw-A-Scientist Test (DAST) with a sample of 63 Mexican high school students. The group of students' pictorial and written descriptions of mathematicians assisted us…

  11. High School Employment and Academic Achievement: A Note for Educators

    ERIC Educational Resources Information Center

    Keister, Mary; Hall, Joshua

    2010-01-01

    Educators are often in a position to affect student decisions to work during the school term. This study reviews and summarizes the literature on the effect that employment during high school has on academic achievement. The available evidence suggests that part-time jobs for high school students are beneficial as long as the number of hours…

  12. What Does Quality Programming Mean for High Achieving Students?

    ERIC Educational Resources Information Center

    Samudzi, Cleo

    2008-01-01

    The Missouri Academy of Science, Mathematics and Computing (Missouri Academy) is a two-year accelerated, early-entrance-to-college, residential school that matches the level, complexity and pace of the curriculum with the readiness and motivation of high achieving high school students. The school is a part of Northwest Missouri State University…

  13. Microsecond gain-switched master oscillator power amplifier (1958 nm) with high pulse energy

    SciTech Connect

    Ke Yin; Weiqiang Yang; Bin Zhang; Ying Li; Jing Hou

    2014-02-28

    An all-fibre master oscillator power amplifier (MOPA) emitting high-energy pulses at 1958 nm is presented. The seed laser is a microsecond gain-switched thulium-doped fibre laser (TDFL) pumped with a commercial 1550-nm pulsed fibre laser. The TDFL operates at a repetition rate f in the range of 10 to 100 kHz. The two-stage thulium-doped fibre amplifier is built to scale the energy of the pulses generated by the seed laser. The maximum output pulse energy higher than 0.5 mJ at 10 kHz is achieved which is comparable with the theoretical maximum extractable pulse energy. The slope efficiency of the second stage amplifier with respect to the pump power is 30.4% at f = 10 kHz. The wavelength of the output pulse laser is centred near 1958 nm at a spectral width of 0.25 nm after amplification. Neither nonlinear effects nor significant amplified spontaneous emission (ASE) is observed in the amplification experiments. (lasers)

  14. Azimuthally unstable resonators for high-power CO[sub 2] lasers with annular gain media

    SciTech Connect

    Ehrlichmann, D.; Habich, U.; Plum, H.D.; Loosen, P.; Herziger, G. )

    1994-06-01

    Stable-unstable resonators have proved suitable for the extraction of a high-quality beam from a gain area that consists of a rectangular slab. Such gain areas have two substantially different transverse dimensions, and the resonators are stable in the small dimension while unstable in the larger one. Using off-axis unstable resonators avoids a central beam obscuration and improves beam quality. The adaptation of stable-unstable resonators to annular gain areas is described in this paper. The resulting resonators are stable in the radial direction and unstable in the azimuthal direction. Different unstable resonators, wound to match the annular geometry, are presented. The resonator modes are calculated numerically using a 3D-diffraction code that considers gain and misalignment. Resonator design parameters are obtained from a geometrical description of the resonator. Experimental results from a diffusion-cooled CO[sub 2] laser confirm theoretical predictions and show that the resonators are capable of extracting beams that are nearly diffraction-limited with high efficiency from an annular gain medium. Output powers of 2 kW have been obtained from a gain length of 1.8 m.

  15. An Analysis of High School Mathematics Achievement and English Language Arts Achievement as Predictors of Science Achievement

    ERIC Educational Resources Information Center

    Edwards, Anthony C.

    2012-01-01

    Science assessments require students to read and comprehend questions and to solve mathematical problems. The purpose of this study is to determine whether the following variables can be used to predict science achievement: English language arts achievement, mathematics achievement, socioeconomic status (SES), limited English proficiency (LEP)…

  16. Alumni Networks--"An Untapped Potential to Gain and Retain Highly-Skilled Workers?"

    ERIC Educational Resources Information Center

    David, Alexandra; Coenen, Frans

    2014-01-01

    In times of increasing skills shortage, regions and particularly non-core regions, need to attract highly-skilled workers. It is better for these regions to (re)attract highly-skilled workers that gained knowledge and contacts elsewhere and because they once lived in the region for study have already ties to the university region than trying to…

  17. Steady State Analysis of Short-wavelength, High-gainFELs in a Large Storage Ring

    SciTech Connect

    Huang, Z.; Bane, K.; Cai, Y.; Chao, A.; Hettel, R.; Pellegrini, C.; /UCLA

    2007-10-15

    Storage ring FELs have operated successfully in the low-gain regime using optical cavities. Discussions of a high-gain FEL in a storage ring typically involve a special bypass to decouple the FEL interaction from the storage ring dynamics. In this paper, we investigate the coupled dynamics of a high-gain FEL in a large storage ring such as PEP and analyze the equilibrium solution. We show that an FEL in the EUV and soft x-ray regimes can be integrated into a very bright storage ring and potentially provides three orders of magnitude improvement in the average brightness at these radiation wavelengths. We also discuss possibilities of seeding with HHG sources to obtain ultra-short, high-peak power EUV and soft x-ray pulses.

  18. The effects of modeling instruction on high school physics academic achievement

    NASA Astrophysics Data System (ADS)

    Wright, Tiffanie L.

    The purpose of this study was to explore whether Modeling Instruction, compared to traditional lecturing, is an effective instructional method to promote academic achievement in selected high school physics classes at a rural middle Tennessee high school. This study used an ex post facto , quasi-experimental research methodology. The independent variables in this study were the instructional methods of teaching. The treatment variable was Modeling Instruction and the control variable was traditional lecture instruction. The Treatment Group consisted of participants in Physical World Concepts who received Modeling Instruction. The Control Group consisted of participants in Physical Science who received traditional lecture instruction. The dependent variable was gains scores on the Force Concepts Inventory (FCI). The participants for this study were 133 students each in both the Treatment and Control Groups (n = 266), who attended a public, high school in rural middle Tennessee. The participants were administered the Force Concepts Inventory (FCI) prior to being taught the mechanics of physics. The FCI data were entered into the computer-based Statistical Package for the Social Science (SPSS). Two independent samples t-tests were conducted to answer the research questions. There was a statistically significant difference between the treatment and control groups concerning the instructional method. Modeling Instructional methods were found to be effective in increasing the academic achievement of students in high school physics. There was no statistically significant difference between FCI gains scores for gender. Gender was found to have no effect on the academic achievement of students in high school physics classes. However, even though there was not a statistically significant difference, female students' gains scores were higher than male students' gains scores when Modeling Instructional methods of teaching were used. Based on these findings, it is recommended

  19. The Grasshopper and the Ant: Motivational Responses of Low-Achieving Students to High-Stakes Testing.

    ERIC Educational Resources Information Center

    Roderick, Melissa; Engel, Mimi

    2001-01-01

    Examined the responses of 102 low achieving sixth and eighth graders to Chicago's highly publicized efforts to end social promotion. Students generally described increased work efforts, and students with high levels of work effort generally had greater than average learning gains and positive outcomes in terms of promotion. About one-third of…

  20. A multifunctional switched-capacitor programmable gain amplifier for high-definition video analog front-ends

    NASA Astrophysics Data System (ADS)

    Hong, Zhang; Jie, Zhang; Mudan, Zhang; Xue, Li; Jun, Cheng

    2015-03-01

    A multifunctional programmable gain amplifier (PGA) that provides gain and offset adjusting abilities for high-definition video analog front-ends (AFE) is presented. With a switched-capacitor structure, the PGA also acts as a sample and holder of the analog-to-digital converter (ADC) in the AFE to reduce the power consumption and chip area of the whole AFE. Furthermore, the PGA converts the single-ended video signal into differential signal for the following ADC to reject common-mode noise and interferences. The 9-bit digital-to-analog converter (DAC) for gain and offset adjusting is embedded into the switched capacitor networks of the PGA. A video AFE integrated circuit based on the proposed PGA is fabricated in a 0.18-μm process. Simulation and measurement results show that the PGA achieves a gain control range of 0.90 to 2.34 and an offset control range of -220 to 220 mV while consuming 10.1 mA from a 1.8 V power supply. Project supported by the National Natural Science Foundation of China (No. 61106027), and the Science and Technology Project of Shanxi Province (No. 2014K05-14).

  1. Supplementary Education: The Hidden Curriculum of High Academic Achievement

    ERIC Educational Resources Information Center

    Gordon, Edmund W., Ed.; Bridglall, Beatrice L., Ed.; Meroe, Aundra Saa, Ed.

    2004-01-01

    In this book, the editors argue that while access to schools that enable and expect academic achievement is a necessary ingredient for the education of students, schools alone may not be sufficient to ensure universally high levels of academic development. Supplemental educational experiences may also be needed. The idea of supplementary education…

  2. Self-Esteem and Academic Achievement of High School Students

    ERIC Educational Resources Information Center

    Moradi Sheykhjan, Tohid; Jabari, Kamran; Rajeswari, K.

    2014-01-01

    The primary purpose of this study was to determine the influence of self-esteem on academic achievement among high school students in Miandoab City of Iran. The methodology of the research is descriptive and correlation that descriptive and inferential statistics were used to analyze the data. Statistical Society includes male and female high…

  3. Middle School Practices Improve Student Achievement in High Poverty Schools.

    ERIC Educational Resources Information Center

    Mertens, Steven B.; Flowers, Nancy

    2003-01-01

    Examined how interdisciplinary team practices and classroom instructional practices affected student achievement in high poverty middle schools in Arkansas, Louisiana, and Mississippi. Found that when the combined effects of family poverty level, teaming and common planning time, and duration of teaming were considered, there was a relationship…

  4. Student Achievement through the Development of Complete High School Culture

    ERIC Educational Resources Information Center

    Lamphere, Michael Frederick, Jr.

    2012-01-01

    This dissertation undertook an investigation of school culture and achievement in the high school setting. The national data set ELS:2002 was used as the pool of variables because it allows for a complete picture of school culture comprising students, parents, administrators, and teachers. The data were selected based on current literature and…

  5. Mercer Middle School Case Study: High Science and Math Achievement

    ERIC Educational Resources Information Center

    Washington State Board of Education, 2010

    2010-01-01

    To spotlight effective practices, the Washington State Board of Education (SBE) is highlighting schools that are closing achievement gaps and performing at high levels. In 2009, the SBE partnered with the Office of Superintendent of Public Instruction (OSPI) to create the Washington Accountability Index. The Index is a new way to measure schools'…

  6. Analysis of Three High-Achieving Young Adolescent Girls

    ERIC Educational Resources Information Center

    Lim, Jae Hoon; Chae, Jeong-Lim; Schinck-Mikel, Amelie G.; Watson, Jimmy

    2013-01-01

    This paper presents an in-depth cross-case analysis of three high-achieving young adolescent girls who had contrasting mathematics learning experiences during the first year of middle school. In particular, this study examines the foundation for their motivation, as well as the dominant mode of learning and academic engagement in relation to three…

  7. The High Trust Classroom: Raising Achievement from the Inside Out

    ERIC Educational Resources Information Center

    Moore, Lonnie

    2009-01-01

    This book provides a roadmap to developing a high-trust classroom, a classroom: (1) With increased student achievement; (2) With few discipline problems; (3) Where students are intrinsically motivated; and (4) Where the teacher can confidently use creative lesson planning. The author presents a simple step by step approach to earning the trust of…

  8. Relationship between High School Leadership Team Practices and Student Achievement

    ERIC Educational Resources Information Center

    McInnis, Timothy M.

    2009-01-01

    This study investigated if a relationship existed between student achievement in 10th grade Missouri Assessment Program mathematics and 11th grade communication arts scores in 2007 and high school leadership team perceptions of the extent to which they demonstrated leadership practices. The secondary purpose was to compare perceptional…

  9. Achievement of U.S. High-School Physics Students.

    ERIC Educational Resources Information Center

    Chandavarkar, Marilda S.; And Others

    1991-01-01

    Reports results of the Second International Science Study concerning achievement in physics of U.S. high school students. Makes comparisons between students of 13 other countries and U.S. students, between first- and second-year U.S. physics students, and between U.S. students tested in the mid-1980s and those tested in 1970. (MDH)

  10. Progress Lags in High School, Especially for Advanced Achievers

    ERIC Educational Resources Information Center

    Education Digest: Essential Readings Condensed for Quick Review, 2012

    2012-01-01

    This report by the Center on Education Policy (CEP), an independent nonprofit organization, examines trends in the achievement of high school students on the state reading/English language arts (ELA) and mathematics tests used for accountability under the No Child Left Behind Act (NCLB). This study confirms that there is reason for concern about…

  11. Development of a 3D FEL code for the simulation of a high-gain harmonic generation experiment.

    SciTech Connect

    Biedron, S. G.

    1999-02-26

    Over the last few years, there has been a growing interest in self-amplified spontaneous emission (SASE) free-electron lasers (FELs) as a means for achieving a fourth-generation light source. In order to correctly and easily simulate the many configurations that have been suggested, such as multi-segmented wigglers and the method of high-gain harmonic generation, we have developed a robust three-dimensional code. The specifics of the code, the comparison to the linear theory as well as future plans will be presented.

  12. Application of variable-gain output feedback for high-alpha control

    NASA Technical Reports Server (NTRS)

    Ostroff, Aaron J.

    1990-01-01

    A variable-gain, optimal, discrete, output feedback design approach that is applied to a nonlinear flight regime is described. The flight regime covers a wide angle-of-attack range that includes stall and post stall. The paper includes brief descriptions of the variable-gain formulation, the discrete-control structure and flight equations used to apply the design approach, and the high performance airplane model used in the application. Both linear and nonlinear analysis are shown for a longitudinal four-model design case with angles of attack of 5, 15, 35, and 60 deg. Linear and nonlinear simulations are compared for a single-point longitudinal design at 60 deg angle of attack. Nonlinear simulations for the four-model, multi-mode, variable-gain design include a longitudinal pitch-up and pitch-down maneuver and high angle-of-attack regulation during a lateral maneuver.

  13. Dynamic properties of a pulse-pumped fiber laser with a short, high-gain cavity

    NASA Astrophysics Data System (ADS)

    Yang, Chaolin; Guo, Junhong; Wei, Pu; Wan, Hongdan; Xu, Ji; Wang, Jin

    2016-09-01

    We demonstrate a pulsed high-gain all-fiber laser without intracavity modulators, where a short and heavily Erbium-doped fiber is used as the gain medium in a ring cavity. By pulsed-pumping this short high gain cavity and tuning an intracavity variable optical coupler, the laser generates optical pulses with a pulse-width of μs at a repetition rate in the order of kHz down to one-shot operation. Furthermore, dynamic properties of this laser are investigated theoretically based on a traveling-wave-model, in which an adaptive-discrete-grid-finite-difference-method is applied. The simulation results validate the experimental results. The demonstrated pulsed laser is compact, flexible and cost-effective, which will have great potential for applications in all-optical sensing and communication systems.

  14. Recent progress in high gain InAs avalanche photodiodes (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Bank, Seth; Maddox, Scott J.; Sun, Wenlu; Nair, Hari P.; Campbell, Joe C.

    2015-08-01

    InAs possesses nearly ideal material properties for the fabrication of near- and mid-infrared avalanche photodiodes (APDs), which result in strong electron-initiated impact ionization and negligible hole-initiated impact ionization [1]. Consequently, InAs multiplication regions exhibit several appealing characteristics, including extremely low excess noise factors and bandwidth independent of gain [2], [3]. These properties make InAs APDs attractive for a number of near- and mid-infrared sensing applications including remote gas sensing, light detection and ranging (LIDAR), and both active and passive imaging. Here, we discuss our recent advances in the growth and fabrication of high gain, low noise InAs APDs. Devices yielded room temperature multiplication gains >300, with much reduced (~10x) lower dark current densities. We will also discuss a likely key contributor to our current performance limitations: silicon diffusion into the intrinsic (multiplication) region from the underlying n-type layer during growth. Future work will focus on increasing the intrinsic region thickness, targeting gains >1000. This work was supported by the Army Research Office (W911NF-10-1-0391). [1] A. R. J. Marshall, C. H. Tan, M. J. Steer, and J. P. R. David, "Electron dominated impact ionization and avalanche gain characteristics in InAs photodiodes," Applied Physics Letters, vol. 93, p. 111107, 2008. [2] A. R. J. Marshall, A. Krysa, S. Zhang, A. S. Idris, S. Xie, J. P. R. David, and C. H. Tan, "High gain InAs avalanche photodiodes," in 6th EMRS DTC Technical Conference, Edinburgh, Scotland, UK, 2009. [3] S. J. Maddox, W. Sun, Z. Lu, H. P. Nair, J. C. Campbell, and S. R. Bank, "Enhanced low-noise gain from InAs avalanche photodiodes with reduced dark current and background doping," Applied Physics Letters, vol. 101, no. 15, pp. 151124-151124-3, Oct. 2012.

  15. On the Fielding of a High Gain, Shock-Ignited Target on the National Ignitiion Facility in the Near Term

    SciTech Connect

    Perkins, L J; Betti, R; Schurtz, G P; Craxton, R S; Dunne, A M; LaFortune, K N; Schmitt, A J; McKenty, P W; Bailey, D S; Lambert, M A; Ribeyre, X; Theobald, W R; Strozzi, D J; Harding, D R; Casner, A; Atzemi, S; Erbert, G V; Andersen, K S; Murakami, M; Comley, A J; Cook, R C; Stephens, R B

    2010-04-12

    Shock ignition, a new concept for igniting thermonuclear fuel, offers the possibility for a near-term ({approx}3-4 years) test of high gain inertial confinement fusion on the National Ignition Facility at less than 1MJ drive energy and without the need for new laser hardware. In shock ignition, compressed fusion fuel is separately ignited by a strong spherically converging shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, fusion energy gains of {approx}60 may be achievable on NIF at laser drive energies around {approx}0.5MJ. Because of the simple all-DT target design, its in-flight robustness, the potential need for only 1D SSD beam smoothing, minimal early time LPI preheat, and use of present (indirect drive) laser hardware, this target may be easier to field on NIF than a conventional (polar) direct drive hotspot ignition target. Like fast ignition, shock ignition has the potential for high fusion yields at low drive energy, but requires only a single laser with less demanding timing and spatial focusing requirements. Of course, conventional symmetry and stability constraints still apply. In this paper we present initial target performance simulations, delineate the critical issues and describe the immediate-term R&D program that must be performed in order to test the potential of a high gain shock ignition target on NIF in the near term.

  16. Gain-guided soliton fiber laser with high-quality rectangle spectrum for ultrafast time-stretch microscopy.

    PubMed

    Hu, Song; Yao, Jian; Liu, Meng; Luo, Ai-Ping; Luo, Zhi-Chao; Xu, Wen-Cheng

    2016-05-16

    The ultrafast time-stretch microscopy has been proposed to enhance the temporal resolution of a microscopy system. The optical source is a key component for ultrafast time-stretch microscopy system. Herein, we reported on the gain-guided soliton fiber laser with high-quality rectangle spectrum for ultrafast time-stretch microscopy. By virtue of the excellent characteristics of the gain-guided soliton, the output power and the 3-dB bandwidth of the stable mode-locked soliton could be up to 3 mW and 33.7 nm with a high-quality rectangle shape, respectively. With the proposed robust optical source, the ultrafast time-stretch microscopy with the 49.6 μm resolution and a scan rate of 11 MHz was achieved without the external optical amplification. The obtained results demonstrated that the gain-guided soliton fiber laser could be used as an alternative high-quality optical source for ultrafast time-stretch microscopy and will introduce some applications in fields such as biology, chemical, and optical sensing. PMID:27409899

  17. Comparative analysis of the intrinsic voltage gain and unit gain frequency between SOI and bulk FinFETs up to high temperatures

    NASA Astrophysics Data System (ADS)

    Oliveira, Alberto Vinicius de; Agopian, Paula Ghedini Der; Martino, Joao Antonio; Simoen, Eddy; Claeys, Cor; Collaert, Nadine; Thean, Aaron

    2016-09-01

    This paper presents an experimental analysis of the analog application figures of merit: the intrinsic voltage gain (AV) and unit gain frequency, focusing on the performance comparison between silicon triple gate pFinFET devices, which were processed on both Si and Silicon-On-Insulator (SOI) substrates. The high temperature (from 25 °C to 150 °C) influence and different channel lengths and fin widths were also taken into account. While the temperature impact on the intrinsic voltage gain (AV) is limited, the unit gain frequency was strongly affected due to the carrier mobility degradation at higher temperatures, for both p- and n-type FinFET structures. In addition, the pFinFETs showed slightly larger AV values compared to the n-type counterparts, whereby the bulk FinFETs presented a higher dispersion than the SOI FinFETs.

  18. Research on synchronization of 15 parallel high gain photoconductive semiconductor switches triggered by high power pulse laser diodes

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Xia, Liansheng; Chen, Yi; Liu, Yi; Yang, Chao; Ye, Mao; Deng, Jianjun

    2015-01-01

    The synchronization of 15 parallel high gain gallium arsenide photoconductive semiconductor switches (GaAs PCSS) has been researched aiming to get higher output voltage. Each PCSS is triggered independently by a high power pulse laser diode. The pulse width, energy, peak power, and central wavelength of the laser pulse are approximately 18 ns, 360 μJ, 20 kW, and 905 nm, respectively. In the stacked Blumlein transmission lines structure, the synchronous conduction of 15 parallel GaAs PCSSs has been achieved by offering optimized bias voltage and laser parameters. The method of synchronization calculation is given, and the synchronization of the 15 parallel GaAs PCSSs is measured as 775 ps. Furthermore, influences of the bias voltage, laser parameters on the synchronization are analyzed. In the output terminal, superimposed by the output voltages of 15 Blumlein transmission lines, the total output voltage reaches up to 328 kV, which is the highest output voltage of GaAs PCSSs that has been reported so far.

  19. Maintaining a High Physical Activity Level Over 20 Years and Weight Gain

    PubMed Central

    Hankinson, Arlene L.; Daviglus, Martha L.; Bouchard, Claude; Carnethon, Mercedes; Lewis, Cora E.; Schreiner, Pamela J.; Liu, Kiang; Sidney, Stephen

    2013-01-01

    Context Data supporting physical activity guidelines to prevent long-term weight gain are sparse, particularly during the period when the highest risk of weight gain occurs. Objective To evaluate the relationship between habitual activity levels and changes in body mass index (BMI) and waist circumference over 20 years. Design, Setting, and Participants The Coronary Artery Risk Development in Young Adults (CARDIA) study is a prospective longitudinal study with 20 years of follow-up, 1985-86 to 2005-06. Habitual activity was defined as maintaining high, moderate, and low activity levels based on sex-specific tertiles of activity scores at baseline. Participants comprised a population-based multi-center cohort (Chicago, Illinois; Birmingham, Alabama; Minneapolis, Minnesota; and Oakland, California) of 3554 men and women aged 18 to 30 years at baseline. Main Outcome Measures Average annual changes in BMI and waist circumference Results Over 20 years, maintaining high levels of activity was associated with smaller gains in BMI and waist circumference compared with low activity levels after adjustment for race, baseline BMI, age, education, cigarette smoking status, alcohol use, and energy intake. Men maintaining high activity gained 2.6 fewer kilograms (+ 0.15 BMI units per year; 95 % confidence interval [CI] 0.11-0.18 vs +0.20 in the lower activity group; 95% CI, 0.17-0.23) and women maintaining higher activity gained 6.1 fewer kilograms (+0.17 BMI units per year; 95 % CI, 0.12-0.21 vs. +0.30 in the lower activity group; 95 % CI, 0.25-0.34). Men maintaining high activity gained 3.1 fewer centimeters in waist circumference (+0.52 cm per year; 95 % CI, 0.43-0.61 cm vs 0.67 cm in the lower activity group; 95 % CI, 0.60-0.75) and women maintaining higher activity gained 3.8 fewer centimeters (+0.49 cm per year; 95 % CI, 0.39-0.58 vs 0.67 cm in the lower activity group; 95 % CI, 0.60-0.75). Conclusion Maintaining high activity levels through young adulthood may lessen

  20. High-power gain-switched Tm(3+)-doped fiber laser.

    PubMed

    Tang, Yulong; Xu, Lin; Yang, Yi; Xu, Jianqiu

    2010-10-25

    Gain-switched by a 1.914-µm Tm:YLF crystal laser, a two-stage Tm(3+) fiber laser has been achieved 100-W level ~2-µm pulsed laser output with a slope efficiency of ~52%. With the 6-m length of Tm fiber, the laser wavelength was centered at 2020 nm with a bandwidth of ~25 nm. Based on an acousto-optic switch, the pulse repetition rate can be modulated from 500 Hz to 50 kHz, and the laser pulse width can be tuned between 75 ns and ~1 µs. The maximum pulse energy was over 10 mJ, and the maximum pulse peak power was 138 kW. By using the fiber-coiling-induced mode-filtering effect, laser beam quality of M2 = 1.01 was obtained. Further scaling the pulse energy and average power from such kind of gain-switched fiber lasers was also discussed. PMID:21164635

  1. A High Gain and Broadband C-Band Aperture-Coupled Patch Antenna

    NASA Astrophysics Data System (ADS)

    Liu, Chunheng; Lu, Yueguang; Du, Chunlei; Luo, Xiangang

    2007-12-01

    A aperture-coupled patch antenna is designed with parasitic elements connecting to the rectangle ring on the bottom of antenna substrate through metal vias, which lead the current induced by patch radiator to the top surface of antenna substrate. Therefore, the effective radiation is enhanced and higher gain is achieved. The bandwidth is broadened simultaneously due to the structure of aperture-coupled patch antenna with parasitic elements. Compared to the conventional aperture-coupled patch antenna, the antenna gain increases averagely 2 dB due to the novel structure. Compared to patch antenna of electromagnetic band-gap, the dimensions of novel patch antenna greatly decreases, which can be used as element in the array antenna. Two kinds manufactured antenna are both measured in an anechoic chamber. The good agreements between numerical simulation and experimental prototype have been obtained.

  2. Parent Involvement Practices of High-Achieving Elementary Science Students

    NASA Astrophysics Data System (ADS)

    Waller, Samara Susan

    This study addressed a prevalence of low achievement in science courses in an urban school district in Georgia. National leaders and educators have identified the improvement of science proficiency as critical to the future of American industry. The purpose of this study was to examine parent involvement in this school district and its contribution to the academic achievement of successful science students. Social capital theory guided this study by suggesting that students achieve best when investments are made into their academic and social development. A collective case study qualitative research design was used to interview 9 parent participants at 2 elementary schools whose children scored in the exceeds category on the Science CRCT. The research questions focused on what these parents did at home to support their children's academic achievement. Data were collected using a semi-structured interview protocol and analyzed through the categorical aggregation of transcribed interviews. Key findings revealed that the parents invested time and resources in 3 practices: communicating high expectations, supporting and developing key skills, and communicating with teachers. These findings contribute to social change at both the local and community level by creating a starting point for teachers, principals, and district leaders to reexamine the value of parent input in the educational process, and by providing data to support the revision of current parent involvement policies. Possibilities for further study building upon the findings of this study may focus on student perceptions of their parents' parenting as it relates to their science achievement.

  3. Academic achievement and career choice in science: Perceptions of African American urban high school students

    NASA Astrophysics Data System (ADS)

    Jones, Sheila Kay

    2007-12-01

    Low test scores in science and fewer career choices in science among African American high school students than their White counterparts has resulted in lower interest during high school and an underrepresentation of African Americans in science and engineering fields. Reasons for this underachievement are not known. This qualitative study used a grounded theory methodology to examine what influence parental involvement, ethnic identity, and early mentoring had on the academic achievement in science and career choice in science of African American urban high school 10th grade students. Using semi-structured open-ended questions in individual interviews and focus groups, twenty participants responded to questions about African American urban high school student achievement in science and their career choice in science. The median age of participants was 15 years; 85% had passed either high school biology or physical science. The findings of the study revealed influences and interactions of selected factors on African American urban high school achievement in science. Sensing potential emerged as the overarching theme with six subthemes; A Taste of Knowledge, Sounds I Hear, Aromatic Barriers, What Others See, The Touch of Others, and The Sixth Sense. These themes correlate to the natural senses of the human body. A disconnect between what science is, their own individual learning and success, and what their participation in science could mean for them and the future of the larger society. Insight into appropriate intervention strategies to improve African American urban high school achievement in science was gained.

  4. High hyperdiploid childhood acute lymphoblastic leukemia: Chromosomal gains as the main driver event.

    PubMed

    Paulsson, Kajsa

    2016-01-01

    High hyperdiploid childhood acute lymphoblastic leukemia is characterized by multiple chromosomal gains. Recent results show that this subtype harbors relatively few genetic abnormalities besides the extra chromosomes, which appear to arise early and are likely the main driver event. Secondary hits primarily target genes in the rat sarcoma (RAS) signaling pathway and histone modifiers. PMID:27308574

  5. 75 FR 61228 - Board Meeting: Technical Lessons Gained From High-Level Nuclear Waste Disposal Efforts

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-04

    ... REVIEW BOARD Board Meeting: Technical Lessons Gained From High-Level Nuclear Waste Disposal Efforts... 1987, the U.S. Nuclear Waste Technical Review Board will meet in Dulles, Virginia, on October 26, 2010... technical issues and to review the technical validity of DOE activities related to implementing the...

  6. High hyperdiploid childhood acute lymphoblastic leukemia: Chromosomal gains as the main driver event

    PubMed Central

    Paulsson, Kajsa

    2016-01-01

    ABSTRACT High hyperdiploid childhood acute lymphoblastic leukemia is characterized by multiple chromosomal gains. Recent results show that this subtype harbors relatively few genetic abnormalities besides the extra chromosomes, which appear to arise early and are likely the main driver event. Secondary hits primarily target genes in the rat sarcoma (RAS) signaling pathway and histone modifiers. PMID:27308574

  7. Deployment/retraction mechanism for solar maximum mission high gain antenna system

    NASA Technical Reports Server (NTRS)

    Bennett, N.; Preiswerk, P.

    1979-01-01

    A mechanism called a deployment/retraction assembly (DRA) which provides not only a stable, but a deployable platform for the high gain antenna system (HGAS) aboard the Solar Maximum Mission (SMM) spacecraft is described. The DRA also has the capability to retract the system upon command.

  8. Prior exercise training blunts short-term high-fat diet-induced weight gain.

    PubMed

    Snook, Laelie A; MacPherson, Rebecca E K; Monaco, Cynthia M F; Frendo-Cumbo, Scott; Castellani, Laura; Peppler, Willem T; Anderson, Zachary G; Buzelle, Samyra L; LeBlanc, Paul J; Holloway, Graham P; Wright, David C

    2016-08-01

    High-fat diets rapidly cause weight gain and glucose intolerance. We sought to determine whether these changes could be mitigated with prior exercise training. Male C57BL/6J mice were exercise-trained by treadmill running (1 h/day, 5 days/wk) for 4 wk. Twenty-four hours after the final bout of exercise, mice were provided with a high-fat diet (HFD; 60% kcal from lard) for 4 days, with no further exercise. In mice fed the HFD prior to exercise training, the results were blunted weight gain, reduced fat mass, and a slight attenuation in glucose intolerance that was mirrored by greater insulin-induced Akt phosphorylation in skeletal muscle compared with sedentary mice fed the HFD. When ad libitum-fed sedentary mice were compared with sedentary high-fat fed mice that were calorie restricted (-30%) to match the weight gain of the previously trained high-fat fed mice, the same attenuated impairments in glucose tolerance were found. Blunted weight gain was associated with a greater capacity to increase energy expenditure in trained compared with sedentary mice when challenged with a HFD. Although mitochondrial enzymes in white adipose tissue and UCP-1 protein content in brown adipose tissue were increased in previously exercised compared with sedentary mice fed a HFD, ex vivo mitochondrial respiration was not increased in either tissue. Our data suggest that prior exercise training attenuates high-fat diet-induced weight gain and glucose intolerance and is associated with a greater ability to increase energy expenditure in response to a high-fat diet. PMID:27101294

  9. Long wavelength, high gain InAsSb strained-layer superlattice photoconductive detectors

    DOEpatents

    Biefeld, Robert M.; Dawson, L. Ralph; Fritz, Ian J.; Kurtz, Steven R.; Zipperian, Thomas E.

    1991-01-01

    A high gain photoconductive device for 8 to 12 .mu.m wavelength radiation including an active semiconductor region extending from a substrate to an exposed face, the region comprising a strained-layer superlattice of alternating layers of two different InAs.sub.1-x Sb.sub.x compounds having x>0.75. A pair of spaced electrodes are provided on the exposed face, and changes in 8 to 12 .mu.m radiation on the exposed face cause a large photoconductive gain between the spaced electrodes.

  10. High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host

    DOEpatents

    Comaskey, Brian J.; Ault, Earl R.; Kuklo, Thomas C.

    2005-07-05

    A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.

  11. The crucial fiber components and gain fiber for high power ytterbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Liao, Lei; Liu, Peng; Xing, Ying-Bin; Wang, Yi-Bo; Dai, Neng-Li; Li, Jin-Yan; He, Bing; Zhou, Jun

    2015-08-01

    We have demonstrated a kW continuous-wave ytterbium-doped all-fiber laser oscillator with 7×1 fused fiber bundle combiner, fiber Bragg grating (FBG) and double-clad gain fiber fabricated by corresponding technologies. The results of experiment that the oscillator had operated at 1079.48nm with 80.94% slope efficiency without the influence of temperature and non-linear effects indicate that fiber components and gain fiber were suitable to high power environment. No evidence of the signal power roll-over showed that this oscillator possess the capacity to highest output with available pump power.

  12. Primary TKA Patients with Quantifiably Balanced Soft-Tissue Achieve Significant Clinical Gains Sooner than Unbalanced Patients

    PubMed Central

    Gustke, Kenneth A.; Golladay, Gregory J.; Roche, Martin W.; Elson, Leah C.; Anderson, Christopher R.

    2014-01-01

    Although total knee arthroplasty has a high success rate, poor outcomes and early revision are associated with ligament imbalance. This multicenter evaluation was performed in order to provide 1-year followup of a previously reported group of patients who had sensor-assisted TKA, comparing the clinical outcomes of quantitatively balanced versus unbalanced patients. At 1 year, the balanced cohort scored 179.3 and 10.4 in KSS and WOMAC, respectively; the unbalanced cohort scored 156.1 and 17.9 in KSS and WOMAC (P < 0.001; P = 0.085). The average activity level scores of quantitatively balanced patients were 68.6 (corresponding to tennis, light jogging, and heavy yard work), while the average activity level of unbalanced patients was 46.7 (corresponding to light housework, and limited walking distances) (P = 0.015). Out of all confounding variables, a balanced articulation was the most significant contributing factor to improved postoperative outcomes (P < 0.001). PMID:25210632

  13. The Will to Achieve: A Phenomenological Study of the Experiences of African American High Achieving Students and Their Parents

    ERIC Educational Resources Information Center

    Spencer, Natalie Faye

    2012-01-01

    The purpose of this research study was to understand the experiences of high achieving African American students and their parents. The experiences of high achieving African American students and their parents have been missing from literature on the academic achievement of African American students. Much of the literature that has been published…

  14. High current gain 4H-SiC bipolar junction transistor

    NASA Astrophysics Data System (ADS)

    Yourun, Zhang; Jinfei, Shi; Ying, Liu; Chengchun, Sun; Fei, Guo; Bo, Zhang

    2016-04-01

    A novel 4H-SiC BJT of high current gain with a suppressing surface traps effect has been proposed. It is effective to improve the current gain due to the lower electrons density in the surface region by extending the emitter metal to overlap the passivation layer on the extrinsic base surface. The electrons trapped in the extrinsic base surface induce the degeneration of SiC BJTs device performance. By modulating the electron recombination rate, the novel structure can increase the current gain to 63.2% compared with conventional ones with the compatible process technology. Optimized sizes are an overlapped metal length of 4 μm, as well as an oxide layer thickness of 50 nm. Project supported by the National Natural Science Foundation of China (Nos. 61306093, 61401075).

  15. Family socioeconomic status, family health, and changes in students' math achievement across high school: A mediational model.

    PubMed

    Barr, Ashley Brooke

    2015-09-01

    In response to recent calls to integrate understandings of socioeconomic disparities in health with understandings of socioeconomic disparities in academic achievement, this study tested a mediational model whereby family socioeconomic status predicted gains in academic achievement across high school through its impact on both student and parent health. Data on over 8000 high school students in the U.S. were obtained from wave 1 (2009-2010) and wave 2 (2012) of the High School Longitudinal Study of 2009 (HSLS:09), and structural equation modeling with latent difference scores was used to determine the role of family health problems in mediating the well-established link between family SES and gains in academic achievement. Using both static and dynamic indicators of family SES, support was found for this mediational model. Higher family SES in 9th grade reduced the probability of students and their parents experiencing a serious health problem in high school, thereby promoting growth in academic achievement. In addition, parent and student health problems mediated the effect of changes in family SES across high school on math achievement gains. Results emphasize the importance of considering the dynamic nature of SES and that both student and parent health should be considered in understanding SES-related disparities in academic achievement. This relational process provides new mechanisms for understanding the intergenerational transmission of socioeconomic status and the status attainment process more broadly. PMID:26189011

  16. High gain/broadband oxide glasses for next generation Raman amplifiers

    NASA Astrophysics Data System (ADS)

    Rivero, Clara A.

    Interest in Raman amplification has undergone a revival due to the rapidly increasing bandwidth requirements for communications transmission, both for long haul and local area networks, and recent developments in the telecom fiber industry and diode laser technology. In contrast to rare earth doped fiber amplifiers, for which the range of wavelengths is fixed and limited, Raman gain bandwidths are larger and the operating wavelength is fixed only by the pump wavelength and the bandwidth of the Raman active medium. In this context, glasses are the material of choice for this application due to their relatively broad spectral response, and ability of making them into optical fiber. This dissertation summarizes findings on different oxide-based glasses that have been synthesized and characterized for their potential application as Raman gain media. Two main glass families were investigated: phosphate-based glass matrices for broadband Raman gain application and TeO2-based glasses for high Raman gain amplification. A phosphate network was preferred for the broadband application since the phosphate Raman active modes can provide amplification above 1000 cm-1, whilst TeO2-based glasses were selected for the high gain application due to their enhanced nonlinearities and polarizabilities among the other oxide-based network formers. The results summarized in this dissertation show that phosphate-based glasses can provide Raman amplification bandwidths of up to 40 THz, an improvement of almost 5 times the bandwidth of SiO2. On the other hand, tellurite-based glasses appear to be promising candidates for high gain discrete Raman applications, providing peak Raman gain coefficients of up to 50 times higher than SiO 2, at 1064 nm. Although, visible spontaneous Raman scattering cross-section measurement is the most frequently used tool for estimating the strength and spectral distribution of Raman gain in materials, especially glasses, there are some issues that one needs to be

  17. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process

    NASA Astrophysics Data System (ADS)

    Wang, Hui–Yuan; Yu, Zhao–Peng; Zhang, Lei; Liu, Chun–Guo; Zha, Min; Wang, Cheng; Jiang, Qi–Chuan

    2015-11-01

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30-60 μm, exhibiting a typical basal texture, fine grains of 1-5 μm and ultrafine (sub) grains of 200-500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application.

  18. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process

    PubMed Central

    Wang, Hui–Yuan; Yu, Zhao–Peng; Zhang, Lei; Liu, Chun–Guo; Zha, Min; Wang, Cheng; Jiang, Qi–Chuan

    2015-01-01

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30–60 μm, exhibiting a typical basal texture, fine grains of 1–5 μm and ultrafine (sub) grains of 200–500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application. PMID:26603776

  19. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process.

    PubMed

    Wang, Hui-Yuan; Yu, Zhao-Peng; Zhang, Lei; Liu, Chun-Guo; Zha, Min; Wang, Cheng; Jiang, Qi-Chuan

    2015-01-01

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30-60 μm, exhibiting a typical basal texture, fine grains of 1-5 μm and ultrafine (sub) grains of 200-500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application. PMID:26603776

  20. Gimbals Drive and Control Electronics Design, Development and Testing of the LRO High Gain Antenna and Solar Array Systems

    NASA Technical Reports Server (NTRS)

    Chernyakov, Boris; Thakore, Kamal

    2010-01-01

    Launched June 18, 2009 on an Atlas V rocket, NASA's Lunar Reconnaissance Orbiter (LRO) is the first step in NASA's Vision for Space Exploration program and for a human return to the Moon. The spacecraft (SC) carries a wide variety of scientific instruments and provides an extraordinary opportunity to study the lunar landscape at resolutions and over time scales never achieved before. The spacecraft systems are designed to enable achievement of LRO's mission requirements. To that end, LRO's mechanical system employed two two-axis gimbal assemblies used to drive the deployment and articulation of the Solar Array System (SAS) and the High Gain Antenna System (HGAS). This paper describes the design, development, integration, and testing of Gimbal Control Electronics (GCE) and Actuators for both the HGAS and SAS systems, as well as flight testing during the on-orbit commissioning phase and lessons learned.

  1. High gain, Fast Scan, Broad Spectrum Parallel Beam Wavelength Dispersive X-ray Spectrometer for SEM

    SciTech Connect

    OHara, David

    2009-05-08

    During contract # DE-FG02-ER83545, Parallax Research, Inc. developed a High gain, Fast Scan Broad Spectrum Parallel beam Wavelength Dispersive X-ray Spectrometer for use on Scanning Electron Microscopes (SEM). This new spectrometer allows very fast high resolution elemental analysis of samples in an electron microscope. By comparison to previous WDS spectrometers, it can change from one energy position to another very quickly and has an extended range compared to some similar products.

  2. A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator

    SciTech Connect

    Tantawi, S.; Dolgashev, V.; Nantista, C.; Pellegrini, C.; Rosenzweig, J.; Travish, G.; /UCLA

    2005-12-14

    High power microwave sources at X-Band, delivering 400 to 500 of megawatts for about 400 ns, have been recently developed. These sources can power a microwave undulator with short period and large gap, and can be used in short wavelength FELs reaching the nm region at a beam energy of about 1 GeV. We present here an experiment designed to demonstrate that microwave undulators have the field quality needed for high gain FELs.

  3. Gaining control: changing relations between executive control and processing speed and their relevance for mathematics achievement over course of the preschool period

    PubMed Central

    Clark, Caron A. C.; Nelson, Jennifer Mize; Garza, John; Sheffield, Tiffany D.; Wiebe, Sandra A.; Espy, Kimberly Andrews

    2014-01-01

    Early executive control (EC) predicts a range of academic outcomes and shows particularly strong associations with children's mathematics achievement. Nonetheless, a major challenge for EC research lies in distinguishing EC from related cognitive constructs that also are linked to achievement outcomes. Developmental cascade models suggest that children's information processing speed is a driving mechanism in cognitive development that supports gains in working memory, inhibitory control and associated cognitive abilities. Accordingly, individual differences in early executive task performance and their relation to mathematics may reflect, at least in part, underlying variation in children's processing speed. The aims of this study were to: (1) examine the degree of overlap between EC and processing speed at different preschool age points; and (2) determine whether EC uniquely predicts children's mathematics achievement after accounting for individual differences in processing speed. As part of a longitudinal, cohort-sequential study, 388 children (50% boys; 44% from low income households) completed the same battery of EC tasks at ages 3, 3.75, 4.5, and 5.25 years. Several of the tasks incorporated baseline speeded naming conditions with minimal EC demands. Multidimensional latent models were used to isolate the variance in executive task performance that did not overlap with baseline processing speed, covarying for child language proficiency. Models for separate age points showed that, while EC did not form a coherent latent factor independent of processing speed at age 3 years, it did emerge as a distinct factor by age 5.25. Although EC at age 3 showed no distinct relation with mathematics achievement independent of processing speed, EC at ages 3.75, 4.5, and 5.25 showed independent, prospective links with mathematics achievement. Findings suggest that EC and processing speed are tightly intertwined in early childhood. As EC becomes progressively decoupled from

  4. Properties of high gain GaAs switches for pulsed power applications

    SciTech Connect

    Zutavern, F.J.; Loubriel, G.M.; Hjalmarson, H.P.; Mar, A.; Helgeson, W.D.; O`Malley, M.W.; Ruebush, M.H.; Falk, R.A.

    1997-09-01

    High gain GaAs photoconductive semiconductor switches (PCSS) are being used in a variety of electrical and optical short pulse applications. The highest power application, which the authors are developing, is a compact, repetitive, short pulse linear induction accelerator. The array of PCSS, which drive the accelerator, will switch 75 kA and 250 kV in 30 ns long pulses at 50 Hz. The accelerator will produce a 700 kV, 7kA electron beam for industrial and military applications. In the low power regime, these switches are being used to switch 400 A and 5 kV to drive laser diode arrays which produce 100 ps optical pulses. These short optical pulses are for military and commercial applications in optical and electrical range sensing, 3D laser radar, and high speed imaging. Both types of these applications demand a better understanding of the switch properties to increase switch lifetime, reduce jitter, optimize optical triggering, and improve overall switch performance. These applications and experiments on the fundamental behavior of high gain GaAs switches will be discussed. Open shutter, infra-red images and time-resolved images of the current filaments, which form during high gain switching, will be presented. Results from optical triggering experiments to produce multiple, diffuse filaments for high current repetitive switching will be described.

  5. Experiences of High-Achieving High School Students Who Have Taken Multiple Concurrent Advanced Placement Courses

    ERIC Educational Resources Information Center

    Milburn, Kristine M.

    2011-01-01

    Problem: An increasing number of high-achieving American high school students are enrolling in multiple Advanced Placement (AP) courses. As a result, high schools face a growing need to understand the impact of taking multiple AP courses concurrently on the social-emotional lives of high-achieving students. Procedures: This phenomenological…

  6. Analog time-reversed ultrasonically encoded (TRUE) optical focusing inside scattering media with high power gain (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ma, Cheng; Xu, Xiao; Wang, Lihong V.

    2016-03-01

    Focusing light deep inside scattering media plays a key role in such biomedical applications as high resolution optical imaging, control, and therapy. In recent years, wavefront shaping technologies have come a long way in controlling light propagation in complex media. A prominent example is time-reversed ultrasonically encoded (TRUE) focusing, which allows noninvasive introduction of "guide stars" inside biological tissue to guide light focusing. By measuring the optical wavefront emanating from an ultrasound focus created at the target location, TRUE determines the desired wavefront non-iteratively, and achieves focusing at the target position via a subsequent optical time reversal. Compared to digital counterparts that employ slow electronic spatial light modulators and cameras, analog TRUE focusing relies on nonlinear photorefractive crystals that inherently accommodate more spatial modes and eliminate the troublesome alignment and data transfer required by digital approaches. However, analog TRUE focusing suffers from its small gain, defined as the energy or power ratio between the focusing and probing beams in the focal volume. Here, by implementing a modified analog TRUE focusing scheme that squeezes the duration of the time-reversed photon packet below the carrier-recombination-limited hologram decay time of the crystal, we demonstrated a photon flux amplification much greater than unity at a preset focal voxel in between two scattering layers. Although the energy gain was still below unity, the unprecedented power gain will nevertheless benefit new biomedical applications.

  7. Suppression of parasitics and pencil beams in the high-gain National Ignition Facility multipass preamplifier

    NASA Astrophysics Data System (ADS)

    Moran, Bryan D.; Dane, C. Brent; Crane, John K.; Martinez, Mikael D.; Penko, Frank A.; Hackel, Lloyd A.

    1998-06-01

    The multi-pass amplifier (MPA) is the last subsystem of the NIF preamplifier, which feeds the main amplification stages of the NIF beamline. The MPA is based on a flashlamp pumped 5-cm diameter by 48 cm long Nd:glass rod amplifier operated at a single pass small signal gain of 15 to 17. The MPA is an off-axis multi-pass image relayed system, which uses two gain isolating image relaying telescopes and passive polarization switching using a Faraday rotator to output the pulse. We describe the MPA system, techniques used to avoid parasitic oscillation at high gain, and suppression of pencil beams. The system is used to generate a well- conditioned 22-joule output from one millijoule input. The output pulse requirements include 22 joules in a square, flat topped beam, and with near field spatial contrast of <5% RMS, square pulse temporal distortion <2.3, and an RMS energy stability of <3%. All of these requirements have been exceeded. The largest impediment to successful operation was overcoming parasitic oscillation. Sources of oscillation could be generally divided into two categories: those due to birefringence, which compromised the polarization contrast of the system; and those due to unwanted reflections from optical surfaces. Baffling in the vacuum spatial filters helps to control the system sensitivity to unwanted stray reflections from flat AR coated surfaces. Stress birefringence in the rather large glass volume of the rod (942 cm3) and the four vacuum loaded lenses are significant, as each of these elements is double passed between each polarizing beam splitter pass. This lowers the polarization contrast of the system, which can prevent the system from operating at sufficient gain. Careful analysis and layout of the MPA architecture has allowed us to address the challenges posed by a system small signal gain of approximately equals 33000 and with an output pulse of as high as 27 joules.

  8. Investigations of SBS and laser gain competition in high-power phase modulated fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Flores, Angel; Dajani, Iyad; Hult, Dane; Robin, Craig

    2014-02-01

    We present experimental results of SBS suppression in high power, monolithic, Yb-doped fiber amplifiers via phase modulated laser gain competition. To narrow the linewidth, two-tone laser gain competition between broad (1036 nm) and narrow linewidth (1064 nm) laser signals is investigated in conjunction with phase modulation and yields pump limited output powers of 600 W. Here integration of both two-tone and pseudo random bit sequence (PRBS) phase modulation concepts, generated SBS enhancement factors of greater than 17x at a modulation frequency of 500 MHz, without reaching the SBS threshold. Significantly, the results represent a near order of magnitude reduction in linewidth over current high-power, monolithic, Yb-doped fiber amplifiers.

  9. High-gain backup antenna design for Pioneer Venus Orbiter spacecraft

    NASA Technical Reports Server (NTRS)

    Glaser, J. I.

    1986-01-01

    The development and performance is described of a high-gain antenna designed to serve on the Pioneer Venus Orbiter spacecraft as a backup to the principal high-gain antenna unit in the unlikely event the mechanically despun antenna mechanism malfunctioned. The final design, a center-fed standing wave array of six sleeve dipoles enclosed in a fiber glass radome, performed successfully, as did all the antennas, on the Pioneer Orbiter spacecraft which was launched on May 20, 1978, as part of the Pioneer Venus mission. Photographs of experimental models giving details of design and construction are included, as well as graphs showing measured pattern and impedance matching characteristics of the subject antenna.

  10. Σ-Δ modulator for a programmable gain, low-power, high-linearity automotive sensor interface

    NASA Astrophysics Data System (ADS)

    de la Rosa, Jose M.; Medeiro, Fernando; Perez-Verdu, Belen; del Rio, Rocio; Rodriguez-Vazquez, Angel

    2003-04-01

    Smart sensors play a critical role in modern automotive electronic systems, covering a wide range of data capturing functions and operating under adverse environmental conditions - temperature range of [-40¦C,175¦C]. In such sensors, the signal provided by transducers is composed of an offset voltage, which depends on the manufacturing process, and a low-frequency signal carrying the information. In practice, the offset voltage is subject to temperature variations, thus causing a shifting of the signal range to be measured. Therefore, the measuring circuit driving the sensor, normally formed by a low-noise preamplifier and an Analog-to-Digital Converter (ADC), must accommodate the complete range of possible offsets and real signals. In this scenario, the use of ADCs based on Sigma-Delta Modulators (SDMs) is convenient for several reasons. On the one hand, the noise-shaping performed by SDMs allows to achieve high resolution (16-17bits), in the band of interest (10-20kHz), with less power consumption than full Nyquist ADCs. On the other hand, the action of feedback renders SDMs very linear, and high-linearity is a must for automotive applications. Last but not least, the robustness of SDMs with respect to circuit imperfections make them suitable to include programmable gain without significant performance degradation. This feature allows to accommodate the complete range of possible offsets and information signals in a sensor interface with relaxed specifications for the preamplifier circuitry. This paper describes the design and implementation of a third-order cascade (2-1) SDM with programmable gain in a 0.35mm CMOS technology - the type of technology commonly employed for automotive applications (deep submicron is mostly employed for telecom). It is capable of handling signals up to 20-kHz bandwidth with 17-bit resolution. The programmable gain is implemented by a capacitor array whose unitary capacitors are connected or disconnected depending on the value of

  11. Generation of nearly hemispherical and high gain azimuthally symmetric patterns with printed circuit antennas

    NASA Astrophysics Data System (ADS)

    Yang, Hung Yu; Alexopoulos, Nicolaos G.

    1987-08-01

    Patttern shaping techniques are discussed for printed circuit antennas such as microstrip dipoles and slot elements. Crossed printed circuit dipoles or a combination of a printed circuit dipole and a slot are employed. It is demonstrated that with the proper choice of substrate or substrate-superstrate parameters it is possible to generate: (1) nearly hemispherical patterns, (2) high-gain azimuthally symmetric patterns, and (3) nearly sec theta patterns.

  12. Optimization of single-step tapering amplitude and energy detuning for high-gain FELs

    NASA Astrophysics Data System (ADS)

    Li, He-Ting; Jia, Qi-Ka

    2015-01-01

    We put forward a method to optimize the single-step tapering amplitude of undulator strength and initial energy tuning of electron beam to maximize the saturation power of high gain free-electron lasers (FELs), based on the physics of longitudinal electron beam phase space. Using the FEL simulation code GENESIS, we numerically demonstrate the accuracy of the estimations for parameters corresponding to the linac coherent light source and the Tesla test facility.

  13. Longitudinal Coherence Preservation and Chirp Evolution in a High Gain Laser Seeded Free Electron Laser Amplifier

    SciTech Connect

    Murphy, J.B.; Wu, Juhao; Wang, X.J.; Watanabe, T.; /BNL, NSLS

    2006-06-07

    In this letter we examine the start-up of a high gain free electron laser in which a frequency-chirped coherent seed laser pulse interacts with a relativistic electron beam. A Green function formalism is used to evaluate the initial value problem. We have fully characterized the startup and evolution through the exponential growth regime. We obtain explicit expressions for the pulse duration, bandwidth and chirp of the amplified light and show that the FEL light remains fully longitudinally coherent.

  14. HIGH GAIN HARMONIC GENERATION UV TO DUV FREE ELECTRON LASERS AT THE NSLS.

    SciTech Connect

    WU, J.; YU, L.H.

    2001-06-18

    In this paper, we present the calculation on the performance of High Gain Harmonic Generation (HGHG) UV to DUV Free Electron Lasers (FELs) at the NSLS. Based on the beam quality and the available undulators at the NSLS, the calculation shows that it is possible to produce fully coherent DUV FEL down to 500 Angstrom, with a peak power of several hundred Mega Watts. One further attractive feature is the possibility to produce ultra short radiation pulse based on such HGHG scheme.

  15. On the ignition of high gain thermonuclear microexplosions with electric pulse power

    NASA Astrophysics Data System (ADS)

    Winterberg, F.

    2004-02-01

    It was recently shown that the ignition of thermonuclear microexplosions seems possible with two Marx generators of modest size, one with a high current lower voltage for compression and confinement, and one with a high voltage lower current for ignition, transmitting their energy to the thermonuclear target by two nested magnetically insulated transmission lines. Here it is shown in much greater detail how this concept has the potential for the ignition of high gain thermonuclear microexplosions with a yield sufficiently low for a thermonuclear reactor and rocket propulsion. The concept also offers the possibility for the concurrent burn of deuterium-tritium with natural uranium or thorium.

  16. Trigeminal high-frequency stimulation produces short- and long-term modification of reflex blink gain

    PubMed Central

    Ryan, Michael; Kaminer, Jaime; Enmore, Patricia

    2013-01-01

    Reflex blinks provide a model system for investigating motor learning in normal and pathological states. We investigated whether high-frequency stimulation (HFS) of the supraorbital branch of the trigeminal nerve before the R2 blink component (HFS-B) decreases reflex blink gain in alert rats. As with humans (Mao JB, Evinger C. J Neurosci 21: RC151, 2001), HFS-B significantly reduced blink size in the first hour after treatment for rats. Repeated days of HFS-B treatment produced long-term depression of blink circuits. Blink gain decreased exponentially across days, indicating a long-term depression of blink circuits. Additionally, the HFS-B protocol became more effective at depressing blink amplitude across days of treatment. This depression was not habituation, because neither long- nor short-term blink changes occurred when HFS was presented after the R2. To investigate whether gain modifications produced by HFS-B involved cerebellar networks, we trained rats in a delay eyelid conditioning paradigm using HFS-B as the unconditioned stimulus and a tone as the conditioned stimulus. As HFS-B depresses blink circuits and delay conditioning enhances blink circuit activity, occlusion should occur if they share neural networks. Rats acquiring robust eyelid conditioning did not exhibit decreases in blink gain, whereas rats developing low levels of eyelid conditioning exhibited weak, short-term reductions in blink gain. These results suggested that delay eyelid conditioning and long-term HFS-B utilize some of the same cerebellar circuits. The ability of repeated HFS-B treatment to depress trigeminal blink circuit activity long term implied that it may be a useful protocol to reduce hyperexcitable blink circuits that underlie diseases like benign essential blepharospasm. PMID:24285868

  17. Unlocking Emergent Talent: Supporting High Achievement of Low-Income, High Ability Students

    ERIC Educational Resources Information Center

    Olszewski-Kubilius, Paula; Clarenbach, Jane

    2012-01-01

    This report takes a comprehensive look at achievement for low-income promising learners--past, present, and future. At its core, it challenges the nation to move beyond its near-singular focus of achieving minimum performance for all students, to identifying and developing the talent of all students who are capable of high achievement, including…

  18. Gate Controlled Photocurrent Generation Mechanisms in High-Gain In₂Se₃ Phototransistors.

    PubMed

    Island, J O; Blanter, S I; Buscema, M; van der Zant, H S J; Castellanos-Gomez, A

    2015-12-01

    Photocurrent in photodetectors incorporating van der Waals materials is typically produced by a combination of photocurrent generation mechanisms that occur simultaneously during operation. Because of this, response times in these devices often yield to slower, high gain processes, which cannot be turned off. Here we report on photodetectors incorporating the layered material In2Se3, which allow complete modulation of a high gain, photogating mechanism in the ON state in favor of fast photoconduction in the OFF state. While photoconduction is largely gate independent, photocurrent from the photogating effect is strongly modulated through application of a back gate voltage. By varying the back gate, we demonstrate control over the dominant mechanism responsible for photocurrent generation. Furthermore, because of the strong photogating effect, these direct-band gap, multilayer phototransistors produce ultrahigh gains of (9.8 ± 2.5) × 10(4) A/W and inferred detectivities of (3.3 ± 0.8) × 10(13) Jones, putting In2Se3 among the most sensitive 2D materials for photodetection studied to date. PMID:26540135

  19. Design of high-gain, wideband antenna using microwave hyperbolic metasurface

    NASA Astrophysics Data System (ADS)

    Zhao, Yan

    2016-05-01

    In this work, we apply hyperbolic metasurfaces (HMSs) to design high-gain and wideband antennas. It is shown that HMSs formed by a single layer of split-ring resonators (SRRs) can be excited to generate highly directive beams. In particular, we suggest two types of the SRR-HMS: a capacitively loaded SRR (CLSRR)-HMS and a substrate-backed double SRR (DSRR)-HMS. Both configurations ensure that the periodicity of the structures is sufficiently small for satisfying the effective medium theory. For the antenna design, we propose a two-layer-stacked configuration for the 2.4 GHz frequency band based on the DSRR-HMS excited by a folded monopole. Measurement results confirm numerical simulations and demonstrate that an antenna gain of more than 5 dBi can be obtained for the frequency range of 2.1 - 2.6 GHz, with a maximum gain of 7.8 dBi at 2.4 GHz.

  20. An investigation into high-achiever and low-achiever knowledge organisation and knowledge processing in concept mapping: A case study

    NASA Astrophysics Data System (ADS)

    Siew Lian, Mary Wong

    1998-09-01

    This study used concept map content analysis and interviews to gain insights into the knowledge organisation and knowledge processing of pre-service teachers. Forty-eight preservice teachers of elementary science from a teachers’ training college in Sarawak, Malaysia, participated in this study. Correlations between achievement and five concept map characteristics showed that there were significant positive correlations ( p<.01) between achievement and: the number of appropriate links; the average number of appropriate concepts per cluster; and, the hierarchy score of subjects’ concept maps, and significant negative correlations ( p<.01) between achievement and: the number of inappropriate links; and, the average number of inappropriate concepts per cluster. Interviews with high-achievers and lowachievers revealed that there were differences in the way they processed knowledge during concept mapping. The high-achievers were more thorough than were the low-achievers in cognitive processing of knowledge, taking time to make sense of concepts, sort and group concepts, form relevant links between concepts, and organise concepts hierarchically. Active cognitive processing of knowledge seems to be related to more complex, well-integrated cognitive structures for the material learned.

  1. High gain and low excess noise near infrared single photon avalanche detector

    NASA Astrophysics Data System (ADS)

    Linga, Krishna; Yevtukhov, Yuriy; Liang, Bing

    2009-05-01

    We present the discrete amplification approach used for development of a very high gain and low excess noise factor in the near infrared wavelength region. The devices have the following performance characteristics: gain > 2X105, excess noise factor < 1.05, rise time < 350ps, fall time < 500ps and operating voltage < 60V. In the photon counting mode, the devices can be operated in the non-gated mode under a constant DC bias and do not require any external quenching circuit. These devices are ideal for researchers in the fields of deep space optical communication, spectroscopy, industrial and scientific instrumentation, Ladar/Lidar, quantum cryptography, night vision and other military, defense and aerospace applications.

  2. Effects of Bandwidth, Compression Speed, and Gain at High Frequencies on Preferences for Amplified Music

    PubMed Central

    2012-01-01

    This article reviews a series of studies on the factors influencing sound quality preferences, mostly for jazz and classical music stimuli. The data were obtained using ratings of individual stimuli or using the method of paired comparisons. For normal-hearing participants, the highest ratings of sound quality were obtained when the reproduction bandwidth was wide (55 to 16000 Hz) and ripples in the frequency response were small (less than ± 5 dB). For hearing-impaired participants listening via a simulated five-channel compression hearing aid with gains set using the CAM2 fitting method, preferences for upper cutoff frequency varied across participants: Some preferred a 7.5- or 10-kHz upper cutoff frequency over a 5-kHz cutoff frequency, and some showed the opposite preference. Preferences for a higher upper cutoff frequency were associated with a shallow high-frequency slope of the audiogram. A subsequent study comparing the CAM2 and NAL-NL2 fitting methods, with gains slightly reduced for participants who were not experienced hearing aid users, showed a consistent preference for CAM2. Since the two methods differ mainly in the gain applied for frequencies above 4 kHz (CAM2 recommending higher gain than NAL-NL2), these results suggest that extending the upper cutoff frequency is beneficial. A system for reducing “overshoot” effects produced by compression gave small but significant benefits for sound quality of a percussion instrument (xylophone). For a high-input level (80 dB SPL), slow compression was preferred over fast compression. PMID:23172008

  3. Effects of bandwidth, compression speed, and gain at high frequencies on preferences for amplified music.

    PubMed

    Moore, Brian C J

    2012-09-01

    This article reviews a series of studies on the factors influencing sound quality preferences, mostly for jazz and classical music stimuli. The data were obtained using ratings of individual stimuli or using the method of paired comparisons. For normal-hearing participants, the highest ratings of sound quality were obtained when the reproduction bandwidth was wide (55 to 16000 Hz) and ripples in the frequency response were small (less than ± 5 dB). For hearing-impaired participants listening via a simulated five-channel compression hearing aid with gains set using the CAM2 fitting method, preferences for upper cutoff frequency varied across participants: Some preferred a 7.5- or 10-kHz upper cutoff frequency over a 5-kHz cutoff frequency, and some showed the opposite preference. Preferences for a higher upper cutoff frequency were associated with a shallow high-frequency slope of the audiogram. A subsequent study comparing the CAM2 and NAL-NL2 fitting methods, with gains slightly reduced for participants who were not experienced hearing aid users, showed a consistent preference for CAM2. Since the two methods differ mainly in the gain applied for frequencies above 4 kHz (CAM2 recommending higher gain than NAL-NL2), these results suggest that extending the upper cutoff frequency is beneficial. A system for reducing "overshoot" effects produced by compression gave small but significant benefits for sound quality of a percussion instrument (xylophone). For a high-input level (80 dB SPL), slow compression was preferred over fast compression. PMID:23172008

  4. Are gender differences in high achievement disappearing? A test in one intellectual domain.

    PubMed

    Howard, Robert W

    2005-05-01

    Males traditionally predominate at upper achievement levels. One general view holds that this is due only to various social factors such as the 'glass ceiling' and lack of female role models. Another view holds that it occurs partly because of innate ability differences, with more males being at upper ability levels. In the last few decades, women have become more achievement focused and competitive and have gained many more opportunities to achieve. The present study examined one intellectual domain, international chess, to quantify its gender differences in achievement and to see if these have been diminishing with the societal changes. Chess is a good test domain because it is a meritocracy, it has objective performance measures, and longitudinal data of a whole population are available. Performance ratings overall and in the top 10, 50 and 100 players of each sex show large gender differences and little convergence over the past three decades, although a few females have become high achievers. The distribution of performance ratings on the January 2004 list shows a higher male mean and evidence for more male variation, just as with traits such as height. Career patterns of players first on the list between 1985 and 1989 show that top males and females entered the list at about the same age but females tend to play fewer games and have shorter careers. In this domain at least, the male predominance is large and has remained roughly constant despite societal changes. PMID:15906890

  5. Achieving high energy absorption capacity in cellular bulk metallic glasses

    PubMed Central

    Chen, S. H.; Chan, K. C.; Wu, F. F.; Xia, L.

    2015-01-01

    Cellular bulk metallic glasses (BMGs) have exhibited excellent energy-absorption performance by inheriting superior strength from the parent BMGs. However, how to achieve high energy absorption capacity in cellular BMGs is vital but mysterious. In this work, using step-by-step observations of the deformation evolution of a series of cellular BMGs, the underlying mechanisms for the remarkable energy absorption capacity have been investigated by studying two influencing key factors: the peak stress and the decay of the peak stress during the plastic-flow plateau stages. An analytical model of the peak stress has been proposed, and the predicted results agree well with the experimental data. The decay of the peak stress has been attributed to the geometry change of the macroscopic cells, the formation of shear bands in the middle of the struts, and the “work-softening” nature of BMGs. The influencing factors such as the effect of the strut thickness and the number of unit cells have also been investigated and discussed. Strategies for achieving higher energy absorption capacity in cellular BMGs have been proposed. PMID:25973781

  6. Achieving high energy absorption capacity in cellular bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Chen, S. H.; Chan, K. C.; Wu, F. F.; Xia, L.

    2015-05-01

    Cellular bulk metallic glasses (BMGs) have exhibited excellent energy-absorption performance by inheriting superior strength from the parent BMGs. However, how to achieve high energy absorption capacity in cellular BMGs is vital but mysterious. In this work, using step-by-step observations of the deformation evolution of a series of cellular BMGs, the underlying mechanisms for the remarkable energy absorption capacity have been investigated by studying two influencing key factors: the peak stress and the decay of the peak stress during the plastic-flow plateau stages. An analytical model of the peak stress has been proposed, and the predicted results agree well with the experimental data. The decay of the peak stress has been attributed to the geometry change of the macroscopic cells, the formation of shear bands in the middle of the struts, and the “work-softening” nature of BMGs. The influencing factors such as the effect of the strut thickness and the number of unit cells have also been investigated and discussed. Strategies for achieving higher energy absorption capacity in cellular BMGs have been proposed.

  7. Fat substitutes promote weight gain in rats consuming high-fat diets

    PubMed Central

    Swithers, Susan E.; Ogden, Sean B.; Davidson, Terry L.

    2011-01-01

    The use of food products designed to mimic the sensory properties of sweet and fat while providing fewer calories has been promoted as a method for reducing food intake and body weight. However, such products may interfere with one mechanism that animals use to regulate energy balance, a learned relationship between the sensory properites of food and the caloric consequences of consuming those foods. Consistent with this hypothesis, previous data have shown that providing rats with sweet tastes that are not associated with the delivery of calories using high-intensity sweeteners results in increased food intake, body weight and adiposity, but only if the diet on which they are maintained also tastes sweet. In the present experiment, we examined whether use of the fat substitute, olestra, would have similar consequences by comparing the effects of consuming high-fat, high-calorie potato chips to the effects of consuming potato chips that sometimes signalled high calories (using high-fat potato chips) and that sometimes signalled lower calories (using non-fat potato chips manufactured with the fat substitute olestra). The results demonstrated that food intake, body weight gain and adiposity were greater for rats that consumed both the high-calorie chips and the low-calorie chips with olestra compared to rats that consumed consuming only the high-calorie chips, but only if animals were also consuming a chow diet that was high in fat and calories. When animals were maintained on a low-fat chow diet, intake, weight gain, and adiposity did not differ significantly based on chip type. However, rats previously exposed to both the low-calorie chips with olestra and the high-calorie chips exhibited increased body weight gain, food intake and adiposity when they were provided with a high fat, high calorie chow diet, even though the potato chips were no longer available. This suggests that the experience with the chips containing olestra affected the ability to predict high

  8. Effects of high CO2 levels on dynamic photosynthesis: carbon gain, mechanisms, and environmental interactions.

    PubMed

    Tomimatsu, Hajime; Tang, Yanhong

    2016-05-01

    Understanding the photosynthetic responses of terrestrial plants to environments with high levels of CO2 is essential to address the ecological effects of elevated atmospheric CO2. Most photosynthetic models used for global carbon issues are based on steady-state photosynthesis, whereby photosynthesis is measured under constant environmental conditions; however, terrestrial plant photosynthesis under natural conditions is highly dynamic, and photosynthetic rates change in response to rapid changes in environmental factors. To predict future contributions of photosynthesis to the global carbon cycle, it is necessary to understand the dynamic nature of photosynthesis in relation to high CO2 levels. In this review, we summarize the current body of knowledge on the photosynthetic response to changes in light intensity under experimentally elevated CO2 conditions. We found that short-term exposure to high CO2 enhances photosynthetic rate, reduces photosynthetic induction time, and reduces post-illumination CO2 burst, resulting in increased leaf carbon gain during dynamic photosynthesis. However, long-term exposure to high CO2 during plant growth has varying effects on dynamic photosynthesis. High levels of CO2 increase the carbon gain in photosynthetic induction in some species, but have no significant effects in other species. Some studies have shown that high CO2 levels reduce the biochemical limitation on RuBP regeneration and Rubisco activation during photosynthetic induction, whereas the effects of high levels of CO2 on stomatal conductance differ among species. Few studies have examined the influence of environmental factors on effects of high levels of CO2 on dynamic photosynthesis. We identified several knowledge gaps that should be addressed to aid future predictions of photosynthesis in high-CO2 environments. PMID:27094437

  9. High-Protein Diet Improves Postoperative Weight Gain After Massive Small-Bowel Resection

    PubMed Central

    Sun, Raphael C.; Choi, Pamela M.; Diaz-Miron, Jose; Sommovilla, Joshua; Guo, Jun; Erwin, Christopher R.

    2016-01-01

    Introduction Short bowel syndrome (SBS) is a morbid clinical condition that results from massive small-bowel resection (SBR). After SBR, there is a dramatic weight loss in the acute postoperative period. Our aim was to determine the impact of a high-protein diet (HPD) on weight gain and body composition in mice after SBR. Methods C57BL/6 mice underwent 50 % proximal SBR. Postoperatively, mice were randomly selected to receive standard rodent liquid diet (LD) (n=6) or an isocaloric HPD (n=9) for 28 days. Mice weights were recorded daily. Body composition analyses were obtained weekly. Student's t test was used for statistical comparisons with p<0.05 considered significant. Results Mice that were fed HPD after SBR returned to baseline weight on average at postoperative day (POD) 8 versus mice that were fed LD that returned to baseline weight on average at POD 22. Total fat mass and lean mass were significantly greater by POD 14 within the HPD group. Both groups of mice demonstrated normal structural adaptation. Conclusion HPD results in greater weight gain and improved body composition in mice after SBR. This finding may be clinically important for patients with SBS since improved weight gain may reduce the time needed for parenteral nutrition. PMID:25519080

  10. High-gain optical Cherenkov oscillator driven by low-voltage electron beam

    SciTech Connect

    Smetanin, I.V.; Oraevsky, A.N.

    1995-12-31

    A novel scheme of high-gain optical (from IR up to UV) Cherenkov-type oscillator driven by low-voltage high-current electron beam is proposed in the present report. In the scheme discussed the magnetized electron beam propagates above the surface of absorbing medium of complex dielectric susceptibility {epsilon}{omega} = {epsilon}{sub 1}({omega}) + i{epsilon}{sub 2}({omega}), {epsilon}{sub 2}>0. We have found that at frequencies {omega} that {beta}{sup 2}> 2{epsilon}{sub 1}/{vert_bar}{epsilon}{vert_bar}{sup 2} ({beta} = v/c, v is the electron velocity), an amplification of co-propagating slow surface electromagnetic wave is possible. In contrast to the conventional Cherenkov oscillators, the absorption condition {epsilon}2>0 is crucial for the gain, which is absent for transparent medium. The physics of this amplification effect is analogous to that of electron beam dissipative instability. The wavelength generated is determined here by dielectric properties of the surface, and does not depend strongly on electron energy. Thus it is possible to use rather compact low voltage ({le} 1MeV) high-current accelerators as drivers. Optimum oscillation conditions are found to be at frequencies near the resonance absorption lines of surface material (i.e. from IR up to UV). The gain up to {approximately}0.5cm{sup -1} in the near IR ({approximately}10THz, SrF{sub 2} absorption line) is possible for 250keV high current (density {approximately}10{sup 12}cm{sup -3}) electron beam.

  11. Achieving High Resolution Timer Events in Virtualized Environment.

    PubMed

    Adamczyk, Blazej; Chydzinski, Andrzej

    2015-01-01

    Virtual Machine Monitors (VMM) have become popular in different application areas. Some applications may require to generate the timer events with high resolution and precision. This however may be challenging due to the complexity of VMMs. In this paper we focus on the timer functionality provided by five different VMMs-Xen, KVM, Qemu, VirtualBox and VMWare. Firstly, we evaluate resolutions and precisions of their timer events. Apparently, provided resolutions and precisions are far too low for some applications (e.g. networking applications with the quality of service). Then, using Xen virtualization we demonstrate the improved timer design that greatly enhances both the resolution and precision of achieved timer events. PMID:26177366

  12. Achieving High Resolution Timer Events in Virtualized Environment

    PubMed Central

    Adamczyk, Blazej; Chydzinski, Andrzej

    2015-01-01

    Virtual Machine Monitors (VMM) have become popular in different application areas. Some applications may require to generate the timer events with high resolution and precision. This however may be challenging due to the complexity of VMMs. In this paper we focus on the timer functionality provided by five different VMMs—Xen, KVM, Qemu, VirtualBox and VMWare. Firstly, we evaluate resolutions and precisions of their timer events. Apparently, provided resolutions and precisions are far too low for some applications (e.g. networking applications with the quality of service). Then, using Xen virtualization we demonstrate the improved timer design that greatly enhances both the resolution and precision of achieved timer events. PMID:26177366

  13. Oscillator Seeding of a High Gain Harmonic Generation FEL in a Radiator-First Configuration

    SciTech Connect

    Gandhi, P.; Wurtele, J.; Penn, G.; Reinsch, M.

    2012-05-20

    A longitudinally coherent X-ray pulse from a high repetition rate free electron laser (FEL) is desired for a wide variety of experimental applications. However, generating such a pulse with a repetition rate greater than 1 MHz is a significant challenge. The desired high repetition rate sources, primarily high harmonic generation with intense lasers in gases or plasmas, do not exist now, and, for the multi-MHz bunch trains that superconducting accelerators can potentially produce, are likely not feasible with current technology. In this paper, we propose to place an oscillator downstream of a radiator. The oscillator generates radiation that is used as a seed for a high gain harmonic generation (HGHG) FEL which is upstream of the oscillator. For the first few pulses the oscillator builds up power and, until power is built up, the radiator has no HGHG seed. As power in the oscillator saturates, the HGHG is seeded and power is produced. The dynamics and stability of this radiator-first scheme is explored analytically and numerically. A single-pass map is derived using a semi-analytic model for FEL gain and saturation. Iteration of the map is shown to be in good agreement with simulations. A numerical example is presented for a soft X-ray FEL.

  14. Achieving ultra-high temperatures with a resistive emitter array

    NASA Astrophysics Data System (ADS)

    Danielson, Tom; Franks, Greg; Holmes, Nicholas; LaVeigne, Joe; Matis, Greg; McHugh, Steve; Norton, Dennis; Vengel, Tony; Lannon, John; Goodwin, Scott

    2016-05-01

    The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community to also develop larger-format infrared emitter arrays to support the testing of systems incorporating these detectors. In addition to larger formats, many scene projector users require much higher simulated temperatures than can be generated with current technology in order to fully evaluate the performance of their systems and associated processing algorithms. Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a new infrared scene projector architecture capable of producing both very large format (>1024 x 1024) resistive emitter arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During earlier phases of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1400 K. New emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures. Test results from pixels fabricated using the new material set will be presented and discussed. A 'scalable' Read In Integrated Circuit (RIIC) is also being developed under the same UHT program to drive the high temperature pixels. This RIIC will utilize through-silicon via (TSV) and Quilt Packaging (QP) technologies to allow seamless tiling of multiple chips to fabricate very large arrays, and thus overcome the yield limitations inherent in large-scale integrated circuits. Results of design verification testing of the completed RIIC will be presented and discussed.

  15. COMPARISON OF TWO DIFFERENT WAVELENGTH TUNING SCHEMES IN A SEEDED HIGH-GAIN FEL.

    SciTech Connect

    SHAFTAN,T.; YU,L.H.

    2004-08-04

    In the following text we analyze and compare results of the two publications ([1], [2]), dedicated to development of the tunable high-gain Free Electron laser (FEL), seeded by an external source. As a conclusion we summarize similarities and differences between these concepts. This note is initiated by the polemics on the similarity of two different schemes of the wavelength tuning in a seeded high-gain FEL. Below we will be calling the scheme, presented by S. Biedron, S, Milton and H. Freund in Nuclear Instruments and Methods of 2001 ([1]), as the first (1st) scheme. The scheme that we developed and presented in the BNL preprint ([2]) will be called as the second (2nd) scheme. The following analysis provides important information on similarities and differences between both techniques. We start by considering the first approach. As we understand, the goal of the Modular Approach is to make X-ray FEL design more flexible [1]. Usual linac-based FELs begin from a long linac with bunch compressor(s) followed by an FEL magnetic system. The essence of the Modular Approach is to break a machine into modules and then recombine these modules in a more efficient way (from the point of view of monetary and/or time constraints). The chapter 3.5 of [1] presents some basic example of Modular Approach. We have studied the scheme, discussed in [1] and illustrated in Fig. 2. Even though very few details of the scheme were presented, it was still sufficient to obtain a complete qualitative picture. Let us begin with the usual phase space of the microbunched beam, which enters a radiator in a prebunched FEL (Fig. 1). The sharp spike (in blue) represents the longitudinal density bunching, which will be the main subject of interest in this discussion. The key principle of a seeded high-gain FEL optimization is to establish this kind of the electron beam phase space at the entrance of the radiator.

  16. Defective TiO2 with high photoconductive gain for efficient and stable planar heterojunction perovskite solar cells.

    PubMed

    Li, Yanbo; Cooper, Jason K; Liu, Wenjun; Sutter-Fella, Carolin M; Amani, Matin; Beeman, Jeffrey W; Javey, Ali; Ager, Joel W; Liu, Yi; Toma, Francesca M; Sharp, Ian D

    2016-01-01

    Formation of planar heterojunction perovskite solar cells exhibiting both high efficiency and stability under continuous operation remains a challenge. Here, we show this can be achieved by using a defective TiO2 thin film as the electron transport layer. TiO2 layers with native defects are deposited by electron beam evaporation in an oxygen-deficient environment. Deep-level hole traps are introduced in the TiO2 layers and contribute to a high photoconductive gain and reduced photocatalytic activity. The high photoconductivity of the TiO2 electron transport layer leads to improved efficiency for the fabricated planar devices. A maximum power conversion efficiency of 19.0% and an average PCE of 17.5% are achieved. In addition, the reduced photocatalytic activity of the TiO2 layer leads to enhanced long-term stability for the planar devices. Under continuous operation near the maximum power point, an efficiency of over 15.4% is demonstrated for 100 h. PMID:27534585

  17. Defective TiO2 with high photoconductive gain for efficient and stable planar heterojunction perovskite solar cells

    PubMed Central

    Li, Yanbo; Cooper, Jason K.; Liu, Wenjun; Sutter-Fella, Carolin M.; Amani, Matin; Beeman, Jeffrey W.; Javey, Ali; Ager, Joel W.; Liu, Yi; Toma, Francesca M.; Sharp, Ian D.

    2016-01-01

    Formation of planar heterojunction perovskite solar cells exhibiting both high efficiency and stability under continuous operation remains a challenge. Here, we show this can be achieved by using a defective TiO2 thin film as the electron transport layer. TiO2 layers with native defects are deposited by electron beam evaporation in an oxygen-deficient environment. Deep-level hole traps are introduced in the TiO2 layers and contribute to a high photoconductive gain and reduced photocatalytic activity. The high photoconductivity of the TiO2 electron transport layer leads to improved efficiency for the fabricated planar devices. A maximum power conversion efficiency of 19.0% and an average PCE of 17.5% are achieved. In addition, the reduced photocatalytic activity of the TiO2 layer leads to enhanced long-term stability for the planar devices. Under continuous operation near the maximum power point, an efficiency of over 15.4% is demonstrated for 100 h. PMID:27534585

  18. EXPERIMENTAL DEMONSTRATION OF WAVELENGTH TUNING IN HIGH-GAIN HARMONIC GENERATION FREE ELECTRON LASER.

    SciTech Connect

    SHAFTAN,T.; JOHNSON,E.; KRINSKY,S.; LOOS,H.; MURPHY,J.B.; RAKOWSKY,G.; ROSE,J.; SHEEHY,B.; SKARITKA,J.; WANG,X.J.; WU,Z.; YU,L.H.

    2004-08-29

    Tunability is one of the key aspects of any laser system. In High-Gain Harmonic Generation Free Electron Laser (HGHG FEL) the seed laser determines the output wavelength. Conventional scheme of tunable HGHG FEL requires tunable seed laser. The alternative scheme [1] is based on compression of the electron bunch with energy-time correlation (chirped bunch) in the FEL dispersive section. The chirped energy modulation, induced by the seed laser with constant wavelength, compressed as the whole bunch undergoes compression. In this paper we discuss experimental verification of the proposed approach at the DUV FEL [2,3] and compare experimental results with analytical estimates.

  19. High Gain Antenna System Deployment Mechanism Integration, Characterization, and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Parong, Fil; Russell, Blair; Garcen, Walter; Rose, Chris; Johnson, Chris; Huber, Craig

    2014-01-01

    The integration and deployment testing of the High Gain Antenna System for the Global Precipitation Measurement mission is summarized. The HGAS deployment mechanism is described. The gravity negation system configuration and its influence on vertical, ground-based, deployment tests are presented with test data and model predictions. A focus is made on the late discovery and resolution of a potentially mission degrading deployment interference condition. The interaction of the flight deployment mechanism, gravity negation mechanism, and use of dynamic modeling is described and lessons learned presented.

  20. High Gain Antenna System Deployment Mechanism Integration, Characterization, and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Parong, Fil; Russell, Blair; Garcen, Walter; Rose, Chris; Johnson, Chris; Huber, Craig

    2014-01-01

    The integration and deployment testing of the High Gain Antenna System (HGAS) for the Global Precipitation Measurement mission is summarized. The HGAS deployment mechanism is described. The gravity negation system configuration and its influence on vertical, ground-based deployment tests are presented with test data and model predictions. A focus is made on the late discovery and resolution of a potentially mission-degrading deployment interference condition. The interaction of the flight deployment mechanism, gravity-negation mechanism, and use of dynamic modeling is described and lessons learned presented

  1. Analysis of FEL-based CeC amplification at high gain limit

    SciTech Connect

    Wang, G.; Litvinenko, V.; Jing, Y.

    2015-05-03

    An analysis of Coherent electron Cooling (CeC) amplifier based on 1D Free Electron Laser (FEL) theory was previously performed with exact solution of the dispersion relation, assuming electrons having Lorentzian energy distribution. At high gain limit, the asymptotic behavior of the FEL amplifier can be better understood by Taylor expanding the exact solution of the dispersion relation with respect to the detuning parameter. In this work, we make quadratic expansion of the dispersion relation for Lorentzian energy distribution and investigate how longitudinal space charge and electrons’ energy spread affect the FEL amplification process.

  2. High gain FEL amplification of charge modulation caused by a hadron

    SciTech Connect

    Litvinenko,V.; Ben-Zvi, I.; Hao, Y.; Kayran, D.; Pozdeyev, E.; Wang, G.; Reiche, S.; Shevchenko, O.; Vinokurov, N. A.

    2008-08-24

    In scheme of coherent electron cooling (CeC) [1,2], a modulation of electron beam density induced by a copropagation hadron is amplified in high gain FEL. The resulting amplified modulation of electron beam, its shape, form and its lethargy determine number of important properties of the coherent electron cooling. In this talk we present both analytical and numerical (using codes RON [3] and Genesis [4]) evaluations of the corresponding Green functions. We also discuss influence of electron beam parameters on the FEL response.

  3. Sub-Poissonian shot noise of a high internal gain injection photon detector.

    PubMed

    Memis, Omer Gokalp; Katsnelson, Alex; Kong, Soon-Cheol; Mohseni, Hooman; Yan, Minjun; Zhang, Shuang; Hossain, Tim; Jin, Niu; Adesida, Ilesanmi

    2008-08-18

    The noise performance of an infrared injection photon detector with very high internal gain was investigated at a wavelength of 1.55 mum. The devices showed sub-Poissonian shot noise with Fano factors around 0.55 at 0.7 V at room temperature. Optical to electrical conversion factors of 3000 electrons per absorbed photon were recorded at 0.7 V. The change in noise-equivalent power with respect to bias voltage was evaluated. The optical to electrical conversion factor and Fano factor were measured under increasing illumination and compared to theoretical expectations. PMID:18711508

  4. ONT High Gain Initiative WRAP (Wide Area Rapid Acoustic Prediction) computational performance section

    SciTech Connect

    McGraw, J.R.; Hedstrom, G.; De Groot, T.

    1990-10-02

    LLNL received a contract during March 1990 to perform three tasks for ONT. This letter report covers Task I which concerned a supercomputing effort in a program termed the High Gain Initiative, which is an anti-submarine (ASW) project that requires substantial computational and signal processing expertise. The core of the computational aspects at the present time is a code called WRAP (Wide Area Rapid Acoustic Prediction). LLNL's objective was to study the WRAP model and determine the feasibility and limits of its optimization. At the present time, the WRAP code runs on a single processor VAX computer.

  5. Method and system for modulation of gain suppression in high average power laser systems

    DOEpatents

    Bayramian, Andrew James

    2012-07-31

    A high average power laser system with modulated gain suppression includes an input aperture associated with a first laser beam extraction path and an output aperture associated with the first laser beam extraction path. The system also includes a pinhole creation laser having an optical output directed along a pinhole creation path and an absorbing material positioned along both the first laser beam extraction path and the pinhole creation path. The system further includes a mechanism operable to translate the absorbing material in a direction crossing the first laser beam extraction laser path and a controller operable to modulate the second laser beam.

  6. Multi-modelling as new estimation schema for high-gain observers

    NASA Astrophysics Data System (ADS)

    Bernat, Jakub; Stepien, Slawomir

    2015-06-01

    The presented paper proposes a novel method of observer design. A new two-layer observer structure is introduced. The first layer consists of multiple high-gain observers. The latter is built to connect the first layer observers into single one. As the new contribution, the new mapping is defined between an unknown state and measurable outputs allowing to explore new estimation schema. Hence, the proposed method enhances the estimation process for linear and nonlinear systems. Furthermore, it is shown that the introduced observation scheme improves the transients. Illustrative examples are calculated to show the properties of the new observation method.

  7. High fat diet promotes achievement of peak bone mass in young rats

    SciTech Connect

    Malvi, Parmanand; Piprode, Vikrant; Chaube, Balkrishna; Pote, Satish T.; Mittal, Monika; Chattopadhyay, Naibedya; Wani, Mohan R.; Bhat, Manoj Kumar

    2014-12-05

    Highlights: • High fat diet helps in achieving peak bone mass at younger age. • Shifting from high fat to normal diet normalizes obese parameters. • Bone parameters are sustained even after withdrawal of high fat diet. - Abstract: The relationship between obesity and bone is complex. Epidemiological studies demonstrate positive as well as negative correlation between obesity and bone health. In the present study, we investigated the impact of high fat diet-induced obesity on peak bone mass. After 9 months of feeding young rats with high fat diet, we observed obesity phenotype in rats with increased body weight, fat mass, serum triglycerides and cholesterol. There were significant increases in serum total alkaline phosphatase, bone mineral density and bone mineral content. By micro-computed tomography (μ-CT), we observed a trend of better trabecular bones with respect to their microarchitecture and geometry. This indicated that high fat diet helps in achieving peak bone mass and microstructure at younger age. We subsequently shifted rats from high fat diet to normal diet for 6 months and evaluated bone/obesity parameters. It was observed that after shifting rats from high fat diet to normal diet, fat mass, serum triglycerides and cholesterol were significantly decreased. Interestingly, the gain in bone mineral density, bone mineral content and trabecular bone parameters by HFD was retained even after body weight and obesity were normalized. These results suggest that fat rich diet during growth could accelerate achievement of peak bone mass that is sustainable even after withdrawal of high fat diet.

  8. How to achieve high-level expression of microbial enzymes

    PubMed Central

    Liu, Long; Yang, Haiquan; Shin, Hyun-dong; Chen, Rachel R.; Li, Jianghua; Du, Guocheng; Chen, Jian

    2013-01-01

    Microbial enzymes have been used in a large number of fields, such as chemical, agricultural and biopharmaceutical industries. The enzyme production rate and yield are the main factors to consider when choosing the appropriate expression system for the production of recombinant proteins. Recombinant enzymes have been expressed in bacteria (e.g., Escherichia coli, Bacillus and lactic acid bacteria), filamentous fungi (e.g., Aspergillus) and yeasts (e.g., Pichia pastoris). The favorable and very advantageous characteristics of these species have resulted in an increasing number of biotechnological applications. Bacterial hosts (e.g., E. coli) can be used to quickly and easily overexpress recombinant enzymes; however, bacterial systems cannot express very large proteins and proteins that require post-translational modifications. The main bacterial expression hosts, with the exception of lactic acid bacteria and filamentous fungi, can produce several toxins which are not compatible with the expression of recombinant enzymes in food and drugs. However, due to the multiplicity of the physiological impacts arising from high-level expression of genes encoding the enzymes and expression hosts, the goal of overproduction can hardly be achieved, and therefore, the yield of recombinant enzymes is limited. In this review, the recent strategies used for the high-level expression of microbial enzymes in the hosts mentioned above are summarized and the prospects are also discussed. We hope this review will contribute to the development of the enzyme-related research field. PMID:23686280

  9. Comparison of the Level of Using Metacognitive Strategies during Study between High Achieving and Low Achieving Prospective Teachers

    ERIC Educational Resources Information Center

    Doganay, Ahmet; Demir, Ozden

    2011-01-01

    The main purpose of this study is to compare the level of using metacognitive strategies during study between high achieving and low achieving prospective classroom teachers. This study was designed as a mixed method study. Metacognitive Learning Strategies Scale developed by Namlu (2004) was used to measure the use of metacognitive strategies…

  10. Gender Differences in Attitudes toward Mathematics between Low-Achieving and High-Achieving Fifth Grade Elementary Students.

    ERIC Educational Resources Information Center

    Rathbone, A. Sue

    Possible gender differences in attitudes toward mathematics were studied between low-achieving and high-achieving fifth-grade students in selected elementary schools within a large, metropolitan area. The attitudes of pre-adolescent children at an intermediate grade level were assessed to determine the effects of rapidly emerging gender-related…

  11. Er(3)/Yb(3)-codoped phosphate glass for short-length high-gain fiber lasers and amplifiers.

    PubMed

    Wang, Fengxiao; Song, Feng; An, Shuangxin; Wan, Wenshun; Guo, Hao; Liu, Shujing; Tian, Jianguo

    2015-02-10

    Er(3)/Yb(3)-codoped phosphate glass with compositions of (78.2-x)P(2)O(5)-14Al(2)O(3)-5Li(2)O-1K(2)O-1.8Yb(2)O(3)-xEr(2)O(3)(x=0.2,0.4,0.6) in mol. % were investigated. Judd-Ofelt (JO) intensity parameters have been calculated to predict radiative properties based on absorption spectra. The stimulated emission cross section (σ(e)) calculated according to McCumber theory was 1.50×10(-20)  cm(2), almost twice larger than values reported before. The effective line width (Δ(eff)), full width at half-maximum (FWHM) and the quality parameters for designing optical amplifier devices were listed in the table compared with other types of phosphate glass matrices. A theoretical model of a Er(3)/Yb(3)-codoped system based on rate and power propagation equations was put forward to investigate the potential advantages of the materials applied for short-length, high-gain fiber amplifiers. A simulated gain of 32.2 and 2.6  dB/cm per unit length was achieved in 12.5-cm-long fiber. PMID:25968040

  12. A new design methodology of obtaining wide band high gain broadband parametric source for infrared wavelength applications

    NASA Astrophysics Data System (ADS)

    Maji, Partha Sona; Roy Chaudhuri, Partha

    2016-03-01

    In this article, we have presented a new design methodology of obtaining wide band parametric sources based on highly nonlinear chalcogenide material of As2S3. The dispersion profile of the photonic crystal fiber (PCF) has been engineered wisely by reducing the diameter of the second air-hole ring to have a favorable higher order dispersion parameter. The parametric gain dependence upon fiber length, pump power, and different pumping wavelengths has been investigated in detail. Based upon the nonlinear four wave mixing phenomenon, we are able to achieve a wideband parametric amplifier with peak gain of 29 dB with FWHM of ≈2000 nm around the IR wavelength by proper tailoring of the dispersion profile of the PCF with a continuous wave Erbium (Er3+)-doped ZBLAN fiber laser emitting at 2.8 μm as the pump source with an average power of 5 W. The new design methodology will unleash a new dimension to the chalcogenide material based investigation for wavelength translation around IR wavelength band.

  13. Verification of the Solar Dynamics Observatory High Gain Antenna Pointing Algorithm Using Flight Data

    NASA Technical Reports Server (NTRS)

    Bourkland, Kristin L.; Liu, Kuo-Chia

    2011-01-01

    The Solar Dynamics Observatory (SDO) is a NASA spacecraft designed to study the Sun. It was launched on February 11, 2010 into a geosynchronous orbit, and uses a suite of attitude sensors and actuators to finely point the spacecraft at the Sun. SDO has three science instruments: the Atmospheric Imaging Assembly (AIA), the Helioseismic and Magnetic Imager (HMI), and the Extreme Ultraviolet Variability Experiment (EVE). SDO uses two High Gain Antennas (HGAs) to send science data to a dedicated ground station in White Sands, New Mexico. In order to meet the science data capture budget, the HGAs must be able to transmit data to the ground for a very large percentage of the time. Each HGA is a dual-axis antenna driven by stepper motors. Both antennas transmit data at all times, but only a single antenna is required in order to meet the transmission rate requirement. For portions of the year, one antenna or the other has an unobstructed view of the White Sands ground station. During other periods, however, the view from both antennas to the Earth is blocked for different portions of the day. During these times of blockage, the two HGAs take turns pointing to White Sands, with the other antenna pointing out to space. The HGAs handover White Sands transmission responsibilities to the unblocked antenna. There are two handover seasons per year, each lasting about 72 days, where the antennas hand off control every twelve hours. The non-tracking antenna slews back to the ground station by following a ground commanded trajectory and arrives approximately 5 minutes before the formerly tracking antenna slews away to point out into space. The SDO Attitude Control System (ACS) runs at 5 Hz, and the HGA Gimbal Control Electronics (GCE) run at 200 Hz. There are 40 opportunities for the gimbals to step each ACS cycle, with a hardware limitation of no more than one step every three GCE cycles. The ACS calculates the desired gimbal motion for tracking the ground station or for slewing

  14. Operating synchrotron light sources with a high gain free electron laser

    NASA Astrophysics Data System (ADS)

    Di Mitri, S.; Cornacchia, M.

    2015-11-01

    Since the 1980s synchrotron light sources have been considered as drivers of a high repetition rate (RR), high gain free electron laser (FEL) inserted in a by-pass line or in the ring itself. As of today, the high peak current required by the laser is not deemed to be compatible with the standard multi-bunch filling pattern of synchrotrons, and in particular with the operation of insertion device (ID) beamlines. We show that this problem can be overcome by virtue of magnetic bunch length compression in a ring section, and that, after lasing, the beam returns to equilibrium conditions without beam quality disruption. Bunch length compression brings a double advantage: the high peak current stimulates a high gain FEL emission, while the large energy spread makes the beam less sensitive to the FEL heating and to the microwave instability in the ring. The beam’s large energy spread at the undulator is matched to the FEL energy bandwidth through a transverse gradient undulator. Feasibility of lasing at 25 nm is shown for the Elettra synchrotron light source at 1 GeV, and scaling to shorter wavelengths as a function of momentum compaction, beam energy and transverse emittance in higher energy, larger rings is discussed. For the Elettra case study, a low (100 Hz) and a high (463 kHz) FEL RR are considered, corresponding to an average FEL output power at the level of ∼1 W (∼1013 photons per pulse) and ∼300 W (∼1011 photons per pulse), respectively. We also find that, as a by-product of compression, the ∼5 W Renieri’s limit on the average FEL power can be overcome. Our conclusion is that existing and planned synchrotron light sources may be made compatible with this new hybrid IDs-plus-FEL operational mode, with little impact on the standard beamlines functionality.

  15. High-power ultralow-noise semiconductor external cavity lasers based on low-confinement optical waveguide gain media

    NASA Astrophysics Data System (ADS)

    Juodawlkis, Paul W.; Loh, William; O'Donnell, Frederick J.; Brattain, Michael A.; Plant, Jason J.

    2010-02-01

    For the past several years, we have been developing a new class of high-power, low-noise semiconductor optical gain medium based on the slab-coupled optical waveguide (SCOW) concept. The key characteristics of the SCOW design are (i) large (> 5 x 5 μm), symmetric, fundamental-transverse-mode operation attained through a combination of coupledmode filtering and low index-contrast, (ii) very low optical confinement factor (Γ ~ 0.3-0.5%), and (iii) low excessoptical loss (αi ~ 0.5 cm-1). The large transverse mode and low confinement factor enables SCOW lasers (SCOWLs) and amplifiers (SCOWAs) having Watt-class output power. The low confinement factor also dictates that the waveguide length be very large (0.5-1 cm) to achieve useful gain, which provides the benefits of small ohmic and thermal resistance. In this paper, we review the operating principles and performance of the SCOW gain medium, and detail its use in 1550-nm single-frequency SCOW external cavity lasers (SCOWECLs). The SCOWECL consists of a doublepass, curved-channel InGaAlAs quantum-well SCOWA and a narrowband (2.5 GHz) fiber Bragg grating (FBG) external cavity. We investigate the impact of the cavity Q on SCOWECL performance by varying the FBG reflectivity. We show that a bench-top SCOWECL having a FBG reflectivity of R = 10% (R = 20%) has a maximum output power of 450 mW (400 mW), linewidth of 52 kHz (28 kHz), and RIN at 2-MHz offset frequency of -155 dB/Hz (-165 dB/Hz).

  16. Polarization beam combination technique for gain saturation effect compensation in high-energy systems

    NASA Astrophysics Data System (ADS)

    Chen, Junchi; Peng, Yujie; Su, Hongpeng; Leng, Yuxin

    2016-06-01

    To compensate for the gain saturation effect in the high-energy laser amplifier, a modified polarization beam combination (PBC) method is introduced to reshape temporal waveform of the injected laser pulse to obtain a controlled high-energy laser pulse shape after amplification. One linearly polarized beam is divided into two orthogonal polarized beams, which spatially recombine together collinearly after propagating different optical paths with relative time delay in PBC structure. The obtained beam with polarization direction being rotated by the following half wave plate is divided and combined again to reform a new beam in another modified polarization beam structure. The reformed beam is injected into three cascaded laser amplifiers. The amplified pulse shape can be controlled by the incident pulse shape and amplifier gain, which is agreeable to the simulation by the Frank-Nodvik equations. Based on the simple method, the various temporal waveform of output pulse with tunable 7 to 20 ns pulse duration can be obtained without interferometric fringes.

  17. Effects of high count rate and gain shift on isotope identification algorithms

    SciTech Connect

    Robinson, Sean M.; Kiff, Scott D.; Ashbaker, Eric D.; Flumerfelt, Eric L.; Salvitti, Matthew

    2009-11-01

    Spectroscopic gamma-ray detectors are used for many research, industrial, and homeland- security applications. Thallium-doped sodium iodide, (NaI(Tl)), scintillation crystals coupled to photomultiplier tubes provide medium-resolution spectral data about the surrounding environment. NaI(Tl)-based detectors, paired with spectral identification algorithms, are often effective for identifying gamma-ray sources by isotope. However, intrinsic limitations for NaI(Tl) systems exist, including gain shifts and spectral marring (e.g., loss of resolution and count-rate saturation) at high count rates. These effects are hardware dependent and have strong effects on the radioisotopic identification capability of NaI(Tl)-based systems. In this work, the effects of high count rate on the response of isotope-identification algorithms are explored. It is shown that a small gain shift of a few tens of keV is sufficient to disturb identification. The onset of this and other spectral effects is estimated for NaI(Tl) crystals, and a mechanism for mitigating these effects by estimating and correcting for them is implemented and evaluated.

  18. Effects of High Count Rate and Gain Shift on Isotope Identification Algorithms

    SciTech Connect

    Robinson, Sean M.; Kiff, Scott D.; Ashbaker, Eric D.; Bender, Sarah E.; Flumerfelt, Eric L.; Salvitti, Matthew; Borgardt, James D.; Woodring, Mitchell L.

    2007-12-31

    Spectroscopic gamma-ray detectors are used for many research applications, as well as Homeland Security screening applications. Sodium iodide (NaI) scintillator crystals coupled with photomultiplier tubes (PMTs) provide medium-resolution spectral data about the surrounding environment. NaI based detectors, paired with spectral identification algorithms, are often effective in identifying sources of interest by isotope. However, intrinsic limitations exist for NaI systems because of gain shifts and spectral marring (e.g., loss of resolution and count-rate saturation) at high count rates. These effects are hardware dependent, and have strong effects on the radioisotopic identification capability of these systems. In this work, the effects of high count rate on the capability of isotope identification algorithms are explored. It is shown that a small gain shift of a few tens of keV is sufficient to disturb identification. The onset of this and other spectral effects are estimated for several systems., and a mechanism for mitigating these effects by estimating and correcting for them is implemented and evaluated.

  19. Redesign of a Variable-Gain Output Feedback Longitudinal Controller Flown on the High-Alpha Research Vehicle (HARV)

    NASA Technical Reports Server (NTRS)

    Ostroff, Aaron J.

    1998-01-01

    This paper describes a redesigned longitudinal controller that flew on the High-Alpha Research Vehicle (HARV) during calendar years (CY) 1995 and 1996. Linear models are developed for both the modified controller and a baseline controller that was flown in CY 1994. The modified controller was developed with three gain sets for flight evaluation, and several linear analysis results are shown comparing the gain sets. A Neal-Smith flying qualities analysis shows that performance for the low- and medium-gain sets is near the level 1 boundary, depending upon the bandwidth assumed, whereas the high-gain set indicates a sensitivity problem. A newly developed high-alpha Bode envelope criterion indicates that the control system gains may be slightly high, even for the low-gain set. A large motion-base simulator in the United Kingdom was used to evaluate the various controllers. Desired performance, which appeared to be satisfactory for flight, was generally met with both the low- and medium-gain sets. Both the high-gain set and the baseline controller were very sensitive, and it was easy to generate pilot-induced oscillation (PIO) in some of the target-tracking maneuvers. Flight target-tracking results varied from level 1 to level 3 and from no sensitivity to PIO. These results were related to pilot technique and whether actuator rate saturation was encountered.

  20. High gain 1.3-μm GaInNAs SOA with fast gain dynamics and enhanced temperature stability

    NASA Astrophysics Data System (ADS)

    Fitsios, D.; Giannoulis, G.; Iliadis, N.; Korpijärvi, V.-M.; Viheriälä, J.; Laakso, A.; Dris, S.; Spyropoulou, M.; Avramopoulos, H.; Kanellos, G. T.; Pleros, N.; Guina, M.

    2014-03-01

    Semiconductor optical amplifiers (SOAs) are a well-established solution of optical access networks. They could prove an enabling technology for DataCom by offering extended range of active optical functionalities. However, in such costand energy-critical applications, high-integration densities increase the operational temperatures and require powerhungry external cooling. Taking a step further towards improving the cost and energy effectiveness of active optical components, we report on the development of a GaInNAs/GaAs (dilute nitride) SOA operating at 1.3μm that exhibits a gain value of 28 dB and combined with excellent temperature stability owing to the large conduction band offset between GaInNAs quantum well and GaAs barrier. Moreover, the characterization results reveal almost no gain variation around the 1320 nm region for a temperature range from 20° to 50° C. The gain recovery time attained values as short as 100 ps, allowing implementation of various signal processing functionalities at 10 Gb/s. The combined parameters are very attractive for application in photonic integrated circuits requiring uncooled operation and thus minimizing power consumption. Moreover, as a result of the insensitivity to heating issues, a higher number of active elements can be integrated on chip-scale circuitry, allowing for higher integration densities and more complex optical on-chip functions. Such component could prove essential for next generation DataCom networks.

  1. Achieving High Throughput for Data Transfer over ATM Networks

    NASA Technical Reports Server (NTRS)

    Johnson, Marjory J.; Townsend, Jeffrey N.

    1996-01-01

    File-transfer rates for ftp are often reported to be relatively slow, compared to the raw bandwidth available in emerging gigabit networks. While a major bottleneck is disk I/O, protocol issues impact performance as well. Ftp was developed and optimized for use over the TCP/IP protocol stack of the Internet. However, TCP has been shown to run inefficiently over ATM. In an effort to maximize network throughput, data-transfer protocols can be developed to run over UDP or directly over IP, rather than over TCP. If error-free transmission is required, techniques for achieving reliable transmission can be included as part of the transfer protocol. However, selected image-processing applications can tolerate a low level of errors in images that are transmitted over a network. In this paper we report on experimental work to develop a high-throughput protocol for unreliable data transfer over ATM networks. We attempt to maximize throughput by keeping the communications pipe full, but still keep packet loss under five percent. We use the Bay Area Gigabit Network Testbed as our experimental platform.

  2. High-Achieving High School Students and Not so High-Achieving College Students: A Look at Lack of Self-Control, Academic Ability, and Performance in College

    ERIC Educational Resources Information Center

    Honken, Nora B.; Ralston, Patricia A. S.

    2013-01-01

    This study investigated the relationship among lack of self-control, academic ability, and academic performance for a cohort of freshman engineering students who were, with a few exceptions, extremely high achievers in high school. Structural equation modeling analysis led to the conclusion that lack of self-control in high school, as measured by…

  3. Learning Styles and High School Students' Chemistry Achievement

    ERIC Educational Resources Information Center

    Uzuntiryaki, Esen

    2007-01-01

    The aim of the present study was to investigate the effects of students' learning styles on their chemistry achievement, and whether matching between teaching and learning styles also affects students' chemistry achievement. Two hundred and sixty-five tenth-grade students enrolled in a chemistry course and seven chemistry teachers participated in…

  4. Does Recreational Computer Use Affect High School Achievement?

    ERIC Educational Resources Information Center

    Bowers, Alex J.; Berland, Matthew

    2013-01-01

    Historically, the relationship between student academic achievement and use of computers for fun and video gaming has been described from a multitude of perspectives, from positive, to negative, to neutral. However, recent research has indicated that computer use and video gaming may be positively associated with achievement, yet these studies…

  5. Student Perception of Academic Achievement Factors at High School

    ERIC Educational Resources Information Center

    Bahar, Mustafa

    2016-01-01

    Measuring the quality of the "product" is elemental in education, and most studies depend on observational data about student achievement factors, focusing overwhelmingly on quantitative data namely achievement scores, school data like attendance, facilities, expenditure class size, etc. But there is little evidence of learner…

  6. Some observations on spin detector response during Galileo high gain antenna deployment

    NASA Technical Reports Server (NTRS)

    Peng, Chia-Yen; Smith, Kenneth S.

    1992-01-01

    This paper summarizes a dynamic analysis conducted in support of the investigation of the anomalous deployment of the Galileo High Gain Antenna on April 11, 1991. The work was focused on modeling the spacecraft spin dynamics to predict and compare the spin detector telemetry during the antenna deployment for possible cause scenarios. The effects of analog and digital low-pass filtering, digitization, and telemetry on the reported spin rate were studied as well. The high frequency phenomena in the spin detector response are masked by the filtering and sampling of the telemetry data. However, the observed spin detector telemetery is consistent with a single rib popping free, and is most likely associated with a rib near the spin detector, or 180 deg opposite.

  7. A Jitter-Mitigating High Gain Antenna Pointing Algorithm for the Solar Dynamics Observatory

    NASA Technical Reports Server (NTRS)

    Bourkland, Kristin L.; Liu, Kuo-Chia; Blaurock, Carl

    2007-01-01

    This paper details a High Gain Antenna (HGA) pointing algorithm which mitigates jitter during the motion of the antennas on the Solar Dynamics Observatory (SDO) spacecraft. SDO has two HGAs which point towards the Earth and send data to a ground station at a high rate. These antennas are required to track the ground station during the spacecraft Inertial and Science modes, which include periods of inertial Sunpointing as well as calibration slews. The HGAs also experience handoff seasons, where the antennas trade off between pointing at the ground station and pointing away from the Earth. The science instruments on SDO require fine Sun pointing and have a very low jitter tolerance. Analysis showed that the nominal tracking and slewing motions of the antennas cause enough jitter to exceed the HGA portion of the jitter budget. The HGA pointing control algorithm was expanded from its original form as a means to mitigate the jitter.

  8. Millimeter-wave double-dipole antennas for high-gain integrated reflector illumination

    NASA Technical Reports Server (NTRS)

    Filipovic, Daniel F.; Ali-Ahmad, Walid Y.; Rebeiz, Gabriel M.

    1992-01-01

    A double-dipole antenna backed by a ground plane has been fabricated for submillimeter wavelengths. The double-dipole antenna is integrated on a thin dielectric membrane with a planar detector at its center. Measured feed patterns at 246 GHz agree well with theory and demonstrate a rotationally symmetric pattern with high coupling efficiency to Gaussian beams. The input impedance is around 50 ohms, and will match well to a Schottky diode or SIS detector. The double-dipole antenna served as the feed for a small machined parabolic reflector. The integrated reflector had a measured gain of 37 dB at 119 microns. This makes the double-dipole antenna ideally suited as a feed for high resolution tracking or for long focal length Cassegrain antenna systems.

  9. Achievement of Hispanic Students in American High Schools: Background Characteristics and Achievement. Contractor Report.

    ERIC Educational Resources Information Center

    Nielsen, Francois; Fernandez, Roberto M.

    Presenting data and analyses from the first wave of the study "High School and Beyond" (HS&B), a longitudinal study of United States high school sophomores and seniors, the report focuses on the composition of the Hispanic tenth and twelfth grade student population with respect to various characteristics; i.e., language use and proficiency, length…

  10. Progress in laboratory high gain ICF (inertial confinement fusion): Prospects for the future

    SciTech Connect

    Storm, E.; Lindl, J.D.; Campbell, E.M.; Bernat, T.P.; Coleman, L.W.; Emmett, J.L.; Hogan, W.J.; Hunt, J.T.; Krupke, W.F.; Lowdermilk, W.H.

    1988-01-01

    Inertial confinement fusion (ICF), a thermonuclear reaction in a small (/approximately/5 mm diameter) fuel capsule filled with a few milligrams of deuterium and tritium, has been the subject of very fruitful experimentation since the early 1970's. High gain ICF is now on the threshold of practical applications. With a Laboratory Microfusion Facility (LMF), these applications will have major implications for national defense, basic and applied science, and power production. With a driver capable of delivering about 10 MJ in a 10-ns pulse at an intensity of /approximately/3 /times/ 10/sup 14/ W/cm/sup 2/, an appropriately configured cryogenic capsule could be compressed to a density of about 200 g/cm/sup 3/ and a temperature of 3--5 keV. Under these conditions, up to 10 mg of DT could be ignited, and with a burn efficiency of about 30%, release up to 1000 MJ of fusion energy, an energy gain of about 100. A thousand megajoules is equivalent to about one quarter ton of TNT, or about 7 gallons of oil--an amount of energy tractable under laboratory conditions and potentially very useful for a variety of applications. 61 refs., 33 figs.

  11. Effects of undulator interruptions on the performance of high-gain FEL amplifiers

    SciTech Connect

    Kim, K.J.; Xie, M.; Pelligrini, C.

    1995-12-31

    The high-gain amplifiers for short wavelength free electron lasers (FELs) such as the LCLS project require a long undulator. The construction of the undulator as well as the FEL operation would become easier if the undulator could be interrupted with drift sections every few gain lengths. We have investigated the influence of such interruption on the FEL performances. Three effects are considered: (i) the diffraction loss, (ii) the phase mismatch and, (iii) the phase smearing due to velocity spread and to dispersion errors. The effect (i) is the loss during the process in which the optical mode in a section of the undulator leaves the undulator, propagates through the free space and then re-enters and re-adjusts in the next section. The effect (ii) is the fact that the phase of the optical beam is displaced with respect to the electrons density modulation for optical FEL interaction due to the slippage of the electron beam in the interruption region. The effect (iii) is the fact that electrons velocity spread, emittance, and dispersion due to misalignment of the quadrupoles used for additional focusing lead to a reduction of the bunching factor. We present an approximate analysis of these effects. When applied to the LCLS parameters, we find that the effect (i) is negligible, the effect (ii) gives a condition on the length of the drift section, and the effects (iii) are small, but could be non-negligible if there are sufficient number of interruptions.

  12. Design of a high-power, high-gain, 2nd harmonic, 22.848 GHz gyroklystron

    NASA Astrophysics Data System (ADS)

    Veale, M.; Purohit, P.; Lawson, W.

    2013-08-01

    In this paper we consider the design of a four-cavity, high-gain K-band gyroklystron experiment for high gradient structure testing. The frequency doubling gyroklystron utilizes a beam voltage of 500 kV and a beam current of 200 A from a magnetron injection gun (MIG) originally designed for a lower-frequency device. The microwave circuit features input and gain cavities in the circular TE011 mode and penultimate and output cavities that operate at the second harmonic in the TE021 mode. We investigate the MIG performance and study the behavior of the circuit for different values of perpendicular to parallel velocity ratio (α = V⊥ / Vz). This microwave tube is expected to be able to produce at least 20 MW of power in 1μs pulses at a repetition rate of at least 120 Hz. A maximum efficiency of 26% and a large signal gain of 58 dB under zero-drive stable conditions were simulated for a velocity ratio equal to 1.35.

  13. Design of a high-power, high-gain, 2nd harmonic, 22.848 GHz gyroklystron

    SciTech Connect

    Veale, M.; Purohit, P.; Lawson, W.

    2013-08-15

    In this paper we consider the design of a four-cavity, high-gain K-band gyroklystron experiment for high gradient structure testing. The frequency doubling gyroklystron utilizes a beam voltage of 500 kV and a beam current of 200 A from a magnetron injection gun (MIG) originally designed for a lower-frequency device. The microwave circuit features input and gain cavities in the circular TE{sub 011} mode and penultimate and output cavities that operate at the second harmonic in the TE{sub 021} mode. We investigate the MIG performance and study the behavior of the circuit for different values of perpendicular to parallel velocity ratio (α= V{sub ⊥}/ V{sub z}). This microwave tube is expected to be able to produce at least 20 MW of power in 1μs pulses at a repetition rate of at least 120 Hz. A maximum efficiency of 26% and a large signal gain of 58 dB under zero-drive stable conditions were simulated for a velocity ratio equal to 1.35.

  14. Gain high-quality colloidal quantum dots directly from natural minerals.

    PubMed

    Wu, Wen-Tian; Liu, Hui; Dong, Chao; Zheng, Wen-Jing; Han, Li-Li; Li, Lan; Qiao, Shi-Zhang; Yang, Jing; Du, Xi-Wen

    2015-03-01

    Green and simple synthesis of high-quality colloidal quantum dots (CQDs) is of great importance and highly anticipated yet not fully implemented. Herein, we achieve the direct conversion of natural minerals to highly uniform, crystalline lead sulfide CQDs based on laser irradiation in liquid. The trivial fragmentation of mineral particles by an intense nanosecond laser was found to create a localized high degree of monomer supersaturation in oleic acid, initiating the LaMer growth of uniform CQDs. The photoconductive device made of these CQDs exhibits a competitive temporal response of photocurrent with those highly sensitive photodetectors based on PbS CQDs reported in the literature. Our synthesis strategy paves the way for the most environmentally friendly and convenient mass production of high-quality uniform CQDs. PMID:25689447

  15. Threatened and Placed at Risk: High Achieving African American Males in Urban High Schools

    ERIC Educational Resources Information Center

    McGee, Ebony O.

    2013-01-01

    This study investigated the risk and protective factors of 11 high-achieving African American males attending 4 urban charter high schools in a Midwestern city to determine what factors account for their resilience and success in mathematics courses, and in high school more generally. This research was guided by a Phenomenological Variant of…

  16. Preferences of High Achieving High School Students in Their Career Development

    ERIC Educational Resources Information Center

    Kim, Mihyeon

    2010-01-01

    The intent of this study was to identify the needs and preference of high-achieving high school students. In terms of career related programs in high school, students listed AP courses and mentoring as their preferred career-related programs. Also, students stated that career guidance by counselors, workshops or sessions, and tech prep were the…

  17. Low noise, low heat dissipation, high gain AC-DC front end amplification for scanning probe microscopy.

    SciTech Connect

    Messina, P.; Fradin, F. Y.; Pittana, P.

    2009-01-01

    We report here on the design, construction and testing of a vacuum compatible AC-DC amplification system for low signal measurements with scanning probes. The most important feature of this new amplification system is incorporated within the head of a scanning tunneling microscope (STM). This is achieved with a very low thermal dissipation radio frequency amplifier at the STM head. The amplifier gain is higher than 40 dB and has a 50 dB maximum. Further, the AC noise figure is 0.7 dB between 100 and 1000 MHz. The noise induced in the DC amplifier is less than 2 pA RMS (root mean square), which enables the microscope to scan over soft insulating molecular layers. Thermal drift at the STM tip-sample interface is below 0.1 nm min{sup -1} both in air and in vacuum operation. Atomic resolution on highly oriented pyrolytic graphite surfaces is reliably achieved. Spin noise measurements are provided as an example of an application.

  18. Suppression of higher mode excitation in a high gain relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Xu, Z.; Jin, X.; Li, Z. H.; Tang, C. X.

    2012-02-01

    Suppressing higher mode excitation is very important in the high gain relativistic klystron amplifier because higher mode can seriously degrade klystron performance and cause pulse shortening. The mechanism of higher mode self-excitation is explored in the PIC simulation, and it is shown the coupling between cavities is the main cause of higher mode self-excitation. The coupling forms the positive feedback loop for higher mode to be excited just like that in the oscillator circuit. The formula for startup current of higher mode self-excitation is developed based on the coupling between cavities. And the corresponding methods are taken to avoid higher mode self-excitation. Finally, mode control is realized in the RKA with output power up to 1.02 GW when driven power is only few kilowatts.

  19. Multicolor High-Gain Free-Electron Laser Driven by Seeded Microbunching Instability.

    PubMed

    Roussel, E; Ferrari, E; Allaria, E; Penco, G; Di Mitri, S; Veronese, M; Danailov, M; Gauthier, D; Giannessi, L

    2015-11-20

    Laser-heater systems are essential tools to control and optimize high-gain free-electron lasers (FELs) working in the x-ray wavelength range. Indeed, these systems induce a controllable increase of the energy spread of the electron bunch. The heating suppresses longitudinal microbunching instability which otherwise would limit the FEL performance. Here, we demonstrate that, through the action of the microbunching instability, a long-wavelength modulation of the electron beam induced by the laser heater at low energy can persist until the beam entrance into the undulators. This coherent longitudinal modulation is exploited to control the FEL spectral properties, in particular, multicolor extreme-ultraviolet FEL pulses can be generated through a frequency mixing of the modulations produced by the laser heater and the seed laser in the electron beam. We present an experimental demonstration of this novel configuration carried out at the FERMI FEL. PMID:26636852

  20. Multicolor High-Gain Free-Electron Laser Driven by Seeded Microbunching Instability

    NASA Astrophysics Data System (ADS)

    Roussel, E.; Ferrari, E.; Allaria, E.; Penco, G.; Di Mitri, S.; Veronese, M.; Danailov, M.; Gauthier, D.; Giannessi, L.

    2015-11-01

    Laser-heater systems are essential tools to control and optimize high-gain free-electron lasers (FELs) working in the x-ray wavelength range. Indeed, these systems induce a controllable increase of the energy spread of the electron bunch. The heating suppresses longitudinal microbunching instability which otherwise would limit the FEL performance. Here, we demonstrate that, through the action of the microbunching instability, a long-wavelength modulation of the electron beam induced by the laser heater at low energy can persist until the beam entrance into the undulators. This coherent longitudinal modulation is exploited to control the FEL spectral properties, in particular, multicolor extreme-ultraviolet FEL pulses can be generated through a frequency mixing of the modulations produced by the laser heater and the seed laser in the electron beam. We present an experimental demonstration of this novel configuration carried out at the FERMI FEL.

  1. RADIATION SPECTRUM STATISTICS IN A HIGH-GAIN FREE-ELECTRON LASER AT 266NM.

    SciTech Connect

    STAFTAN, T.; SHEEHY, B.; LOOS, H.; YU, L.H.; MURPHY, J.B.; KRINSKY, S.; ROSE, J.; WATANABE, T.; LIU, D.; WANG, X.J.

    2005-08-21

    High Gain Harmonic Generation FEL is in operations at the DUV-FEL facility (BNL). During HGHG FEL characterization we have measured a set of data demonstrating basic properties of the FEL radiation and compared them with analytic calculations [1]. This paper describes continuation of characterization of the HGHG FEL radiation output, based on the spectral measurements. We discuss analysis of an experiment at which the tunability concept of a seeded FEL with a fixed seed wavelength has been verified [2]. During the experiment we recorded about 200 radiation spectra corresponding to different energy chirps in the electron beam. We have analyzed this set of spectral data to obtain statistical properties of HGHG radiation. Correlations and trends in the radiation spectrum at 266 nm have been observed and studied.

  2. Calibration of Gimbaled Platforms: The Solar Dynamics Observatory High Gain Antennas

    NASA Technical Reports Server (NTRS)

    Hashmall, Joseph A.

    2006-01-01

    Simple parameterization of gimbaled platform pointing produces a complete set of 13 calibration parameters-9 misalignment angles, 2 scale factors and 2 biases. By modifying the parameter representation, redundancy can be eliminated and a minimum set of 9 independent parameters defined. These consist of 5 misalignment angles, 2 scale factors, and 2 biases. Of these, only 4 misalignment angles and 2 biases are significant for the Solar Dynamics Observatory (SDO) High Gain Antennas (HGAs). An algorithm to determine these parameters after launch has been developed and tested with simulated SDO data. The algorithm consists of a direct minimization of the root-sum-square of the differences between expected power and measured power. The results show that sufficient parameter accuracy can be attained even when time-dependent thermal distortions are present, if measurements from a pattern of intentional offset pointing positions is included.

  3. Image-Guided Radio-Frequency Gain Calibration for High-Field MRI

    PubMed Central

    Breton, Elodie; McGorty, KellyAnne; Wiggins, Graham C.; Axel, Leon; Kim, Daniel

    2010-01-01

    High-field (≥ 3T) MRI provides a means to increase the signal-to-noise ratio, due to its higher tissue magnetization compared with 1.5T. However, both the static magnetic field (B0) and the transmit radio-frequency (RF) field (B1+) inhomogeneities are comparatively higher than those at 1.5T. These challenging factors at high-field strengths make it more difficult to accurately calibrate the transmit RF gain using standard RF calibration procedures. An image-based RF calibration procedure was therefore developed, in order to accurately calibrate the transmit RF gain within a specific region-of-interest (ROI). Using a single-shot ultra-fast gradient echo pulse sequence with centric k-space reordering, a series of “saturation-no-recovery” images was acquired by varying the flip angle of the preconditioning pulse. In the resulting images, the signal null occurs in regions where the flip angle of the preconditioning pulse is 90°. For a given ROI, the mean signal can be plotted as a function of the nominal flip angle, and the resulting curve can be used to quantitatively identify the signal null. This image-guided RF calibration procedure was evaluated through phantom and volunteer imaging experiments at 3T and 7T. The image-guided RF calibration results in vitro were consistent with standard B0 and B1+ maps. The standard automated RF calibration procedure produced approximately 20% and 15–30% relative error in the transmit RF gain in the left kidney at 3T and brain at 7T, respectively. For initial application, a T2 mapping pulse sequence was applied at 7T. The T2 measurements in the thalamus at 7T were 60.6 ms and 48.2 ms using the standard and image-guided RF calibration procedures, respectively. This rapid, image-guided RF calibration procedure can be used to optimally calibrate the flip angle for a given ROI and thus minimize measurement errors for quantitative MRI and MR spectroscopy. PMID:20014333

  4. The Effect of Music Participation on Mathematical Achievement and Overall Academic Achievement of High School Students

    ERIC Educational Resources Information Center

    Cox, H. A.; Stephens, L. J.

    2006-01-01

    A study was conducted on high school students, comparing those with some music credits to those with none. No statistically significant difference was found in their mean math grade point averages (GPA) or their mean cumulative GPAs. Students were then separated into two groups based on the number of music credits. Students who had earned at least…

  5. Evolution of electron beam phase space distribution in a high-gain FEL

    SciTech Connect

    Webb,S.D.; Litvinenko, V. N.

    2009-08-23

    FEL-based coherent electron cooling (CEC) offers a new avenue to achieve high luminosities in high energy colliders such as RHIC, LHC, and eRHIC. Traditional treatments consider the FEL as an amplifier of optical waves with specific initial conditions, focusing on the resulting field. CEC requires knowledge of the phase space distribution of the electron beam in the FEL. We present 1D analytical results for the phase space distribution of an electron beam with an arbitrary initial current profile, and discuss approaches of expanding to 3D results.

  6. Academic attainment and the high school science experiences among high-achieving African American males

    NASA Astrophysics Data System (ADS)

    Trice, Rodney Nathaniel

    This study examines the educational experiences of high achieving African American males. More specifically, it analyzes the influences on their successful navigation through high school science. Through a series of interviews, observations, questionnaires, science portfolios, and review of existing data the researcher attempted to obtain a deeper understanding of high achieving African American males and their limitations to academic attainment and high school science experiences. The investigation is limited to ten high achieving African American male science students at Woodcrest High School. Woodcrest is situated at the cross section of a suburban and rural community located in the southeastern section of the United States. Although this investigation involves African American males, all of whom are successful in school, its findings should not be generalized to this nor any other group of students. The research question that guided this study is: What are the limitations to academic attainment and the high school science experiences of high achieving African American males? The student participants expose how suspension and expulsion, special education placement, academic tracking, science instruction, and teacher expectation influence academic achievement. The role parents play, student self-concept, peer relationships, and student learning styles are also analyzed. The anthology of data rendered three overarching themes: (1) unequal access to education, (2) maintenance of unfair educational structures, and (3) authentic characterizations of African American males. Often the policies and practices set in place by school officials aid in creating hurdles to academic achievement. These policies and practices are often formed without meaningful consideration of the unintended consequences that may affect different student populations, particularly the most vulnerable. The findings from this study expose that high achieving African American males face major

  7. Fluorene- and benzofluorene-cored oligomers as low threshold and high gain amplifying media

    NASA Astrophysics Data System (ADS)

    Kazlauskas, Karolis; Kreiza, Gediminas; Bobrovas, Olegas; AdomÄ--nienÄ--, Ona; AdomÄ--nas, Povilas; Jankauskas, Vygintas; JuršÄ--nas, Saulius

    2015-07-01

    Deliberate control of intermolecular interactions in fluorene- and benzofluorene-cored oligomers was attempted via introduction of different-length alkyl moieties to attain high emission amplification and low amplified spontaneous emission (ASE) threshold at high oligomer concentrations. Containing fluorenyl peripheral groups decorated with different-length alkyl moieties, the oligomers were found to express weak concentration quenching of emission, yet excellent carrier drift mobilities (close to 10-2 cm2/V/s) in the amorphous films. Owing to the larger radiative decay rates (>1.0 × 109 s-1) and smaller concentration quenching, fluorene-cored oligomers exhibited down to one order of magnitude lower ASE thresholds at higher concentrations as compared to those of benzofluorene counterparts. The lowest threshold (300 W/cm2) obtained for the fluorene-cored oligomers at the concentration of 50 wt % in polymer matrix is among the lowest reported for solution-processed amorphous films in ambient conditions, what makes the oligomers promising for lasing application. Great potential in emission amplification was confirmed by high maximum net gain (77 cm-1) revealed for these compounds. Although the photostability of the oligomers was affected by photo-oxidation, it was found to be comparable to that of various organic lasing materials including some commercial laser dyes evaluated under similar excitation conditions.

  8. Fluorene- and benzofluorene-cored oligomers as low threshold and high gain amplifying media

    SciTech Connect

    Kazlauskas, Karolis Kreiza, Gediminas; Bobrovas, Olegas; Adomėnienė, Ona; Adomėnas, Povilas; Juršėnas, Saulius; Jankauskas, Vygintas

    2015-07-27

    Deliberate control of intermolecular interactions in fluorene- and benzofluorene-cored oligomers was attempted via introduction of different-length alkyl moieties to attain high emission amplification and low amplified spontaneous emission (ASE) threshold at high oligomer concentrations. Containing fluorenyl peripheral groups decorated with different-length alkyl moieties, the oligomers were found to express weak concentration quenching of emission, yet excellent carrier drift mobilities (close to 10{sup −2} cm{sup 2}/V/s) in the amorphous films. Owing to the larger radiative decay rates (>1.0 × 10{sup 9 }s{sup −1}) and smaller concentration quenching, fluorene-cored oligomers exhibited down to one order of magnitude lower ASE thresholds at higher concentrations as compared to those of benzofluorene counterparts. The lowest threshold (300 W/cm{sup 2}) obtained for the fluorene-cored oligomers at the concentration of 50 wt % in polymer matrix is among the lowest reported for solution-processed amorphous films in ambient conditions, what makes the oligomers promising for lasing application. Great potential in emission amplification was confirmed by high maximum net gain (77 cm{sup −1}) revealed for these compounds. Although the photostability of the oligomers was affected by photo-oxidation, it was found to be comparable to that of various organic lasing materials including some commercial laser dyes evaluated under similar excitation conditions.

  9. Parenting Style, Perfectionism, and Creativity in High-Ability and High-Achieving Young Adults

    ERIC Educational Resources Information Center

    Miller, Angie L.; Lambert, Amber D.; Speirs Neumeister, Kristie L.

    2012-01-01

    The current study explores the potential relationships among perceived parenting style, perfectionism, and creativity in a high-ability and high-achieving young adult population. Using data from 323 honors college students at a Midwestern university, bivariate correlations suggested positive relationships between (a) permissive parenting style and…

  10. Success Despite Socioeconomics: A Case Study of a High-Achieving, High-Poverty School

    ERIC Educational Resources Information Center

    Tilley, Thomas Brent; Smith, Samuel J.; Claxton, Russell L.

    2012-01-01

    This case study of a high-achieving, high-poverty school describes the school's leadership, culture, and programs that contributed to its success. Data were collected from two surveys (the School Culture Survey and the Vanderbilt Assessment of Leadership in Education), observations at the school site, and interviews with school personnel. The…

  11. "Brains before "Beauty"?" High Achieving Girls, School and Gender Identities

    ERIC Educational Resources Information Center

    Skelton, Christine; Francis, Becky; Read, Barbara

    2010-01-01

    In recent years educational policy on gender and achievement has concentrated on boys' underachievement, frequently comparing it with the academic success of girls. This has encouraged a perception of girls as the "winners" of the educational stakes and assumes that they no longer experience the kinds of gender inequalities identified in earlier…

  12. Cooperative Learning: A Standard for High Achievement. The Nutshell Series.

    ERIC Educational Resources Information Center

    Williams, R. Bruce

    2007-01-01

    This book reveals some of the structural complexities involved in implementing authentic cooperative learning in the classroom. It also suggests that when full cooperative learning structures are implemented, the benefits in student achievement often can be astounding. Descriptions, decisions, designs, and developments, a simple four-part scheme,…

  13. Dominant Achievement Goals across Tracks in High School

    ERIC Educational Resources Information Center

    Scheltinga, Peter A. M.; Kuyper, Hans; Timmermans, Anneke C.; van der Werf, Greetje P. C.

    2016-01-01

    The dominant achievement goals (DAGs) of 7,008 students in the third grade of Dutch secondary education (US grade 9) were investigated, based on Elliot & McGregors' 2 × 2 framework (2001), in relation to track-level and motivational variables. We found the mastery-approach goal and the performance-approach goal, generally considered adaptive,…

  14. All AlGaN epitaxial structure solar-blind avalanche photodiodes with high efficiency and high gain

    NASA Astrophysics Data System (ADS)

    Wu, Hualong; Wu, Weicong; Zhang, Hongxian; Chen, Yingda; Wu, Zhisheng; Wang, Gang; Jiang, Hao

    2016-05-01

    Solar-blind avalanche photodiodes were fabricated with an all AlGaN-based epitaxial structure on sapphire by metal–organic chemical vapor deposition. The devices demonstrate a maximum responsivity of 114.1 mA/W at 278 nm and zero bias, corresponding to an external quantum efficiency (EQE) of 52.7%. The EQE improves to 64.8% under a bias of ‑10 V. Avalanche gain higher than 2 × 104 was obtained at a bias of ‑140 V. The high performance is attributed to the all AlGaN-based p–i–n structure comprised of undoped and Si-doped n-type Al0.4Ga0.6N on a high quality AlN layer and highly conductive p-type AlGaN grown with In-surfactant-assisted Mg-delta doping.

  15. Normal Visual Acuity and Electrophysiological Contrast Gain in Adults with High-Functioning Autism Spectrum Disorder.

    PubMed

    Tebartz van Elst, Ludger; Bach, Michael; Blessing, Julia; Riedel, Andreas; Bubl, Emanuel

    2015-01-01

    A common neurodevelopmental disorder, autism spectrum disorder (ASD), is defined by specific patterns in social perception, social competence, communication, highly circumscribed interests, and a strong subjective need for behavioral routines. Furthermore, distinctive features of visual perception, such as markedly reduced eye contact and a tendency to focus more on small, visual items than on holistic perception, have long been recognized as typical ASD characteristics. Recent debate in the scientific community discusses whether the physiology of low-level visual perception might explain such higher visual abnormalities. While reports of this enhanced, "eagle-like" visual acuity contained methodological errors and could not be substantiated, several authors have reported alterations in even earlier stages of visual processing, such as contrast perception and motion perception at the occipital cortex level. Therefore, in this project, we have investigated the electrophysiology of very early visual processing by analyzing the pattern electroretinogram-based contrast gain, the background noise amplitude, and the psychophysical visual acuities of participants with high-functioning ASD and controls with equal education. Based on earlier findings, we hypothesized that alterations in early vision would be present in ASD participants. This study included 33 individuals with ASD (11 female) and 33 control individuals (12 female). The groups were matched in terms of age, gender, and education level. We found no evidence of altered electrophysiological retinal contrast processing or psychophysical measured visual acuities. There appears to be no evidence for abnormalities in retinal visual processing in ASD patients, at least with respect to contrast detection. PMID:26379525

  16. Transportation-cyber-physical-systems-oriented engine cylinder pressure estimation using high gain observer

    NASA Astrophysics Data System (ADS)

    Li, Yong-Fu; Xiao-Pei, Kou; Zheng, Tai-Xiong; Li, Yin-Guo

    2015-05-01

    In transportation cyber-physical-systems (T-CPS), vehicle-to-vehicle (V2V) communications play an important role in the coordination between individual vehicles as well as between vehicles and the roadside infrastructures, and engine cylinder pressure is significant for engine diagnosis on-line and torque control within the information exchange process under V2V communications. However, the parametric uncertainties caused from measurement noise in T-CPS lead to the dynamic performance deterioration of the engine cylinder pressure estimation. Considering the high accuracy requirement under V2V communications, a high gain observer based on the engine dynamic model is designed to improve the accuracy of pressure estimation. Then, the analyses about convergence, converge speed and stability of the corresponding error model are conducted using the Laplace and Lyapunov method. Finally, results from combination of Simulink with GT-Power based numerical experiments and comparisons demonstrate the effectiveness of the proposed approach with respect to robustness and accuracy. Project supported by the National Natural Science Foundation of China (Grant No. 61304197), the Scientific and Technological Talents of Chongqing, China (Grant No. cstc2014kjrc-qnrc30002), the Key Project of Application and Development of Chongqing, China (Grant No. cstc2014yykfB40001), the Natural Science Funds of Chongqing, China (Grant No. cstc2014jcyjA60003), and the Doctoral Start-up Funds of Chongqing University of Posts and Telecommunications, China (Grant No. A2012-26).

  17. Normal Visual Acuity and Electrophysiological Contrast Gain in Adults with High-Functioning Autism Spectrum Disorder

    PubMed Central

    Tebartz van Elst, Ludger; Bach, Michael; Blessing, Julia; Riedel, Andreas; Bubl, Emanuel

    2015-01-01

    A common neurodevelopmental disorder, autism spectrum disorder (ASD), is defined by specific patterns in social perception, social competence, communication, highly circumscribed interests, and a strong subjective need for behavioral routines. Furthermore, distinctive features of visual perception, such as markedly reduced eye contact and a tendency to focus more on small, visual items than on holistic perception, have long been recognized as typical ASD characteristics. Recent debate in the scientific community discusses whether the physiology of low-level visual perception might explain such higher visual abnormalities. While reports of this enhanced, “eagle-like” visual acuity contained methodological errors and could not be substantiated, several authors have reported alterations in even earlier stages of visual processing, such as contrast perception and motion perception at the occipital cortex level. Therefore, in this project, we have investigated the electrophysiology of very early visual processing by analyzing the pattern electroretinogram-based contrast gain, the background noise amplitude, and the psychophysical visual acuities of participants with high-functioning ASD and controls with equal education. Based on earlier findings, we hypothesized that alterations in early vision would be present in ASD participants. This study included 33 individuals with ASD (11 female) and 33 control individuals (12 female). The groups were matched in terms of age, gender, and education level. We found no evidence of altered electrophysiological retinal contrast processing or psychophysical measured visual acuities. There appears to be no evidence for abnormalities in retinal visual processing in ASD patients, at least with respect to contrast detection. PMID:26379525

  18. Germinated Waxy Black Rice Suppresses Weight Gain in High-Fat Diet-Induced Obese Mice.

    PubMed

    Lim, Won-Chul; Ho, Jin-Nyoung; Lee, Hee-Seop; Cho, Hong-Yon

    2016-04-01

    This study was performed to investigate the antiobesity effect of germinated waxy black rice (GWBR) in high-fat diet (HFD)-induced obese mice. The mice were divided into a normal diet (ND) group, HFD group, and 2 test groups for 8 weeks: 2.5% GWBR-supplemented (GWBR-2.5) group and 5% GWBR-supplemented (GWBR-5) group. Supplementing with GWBR significantly reduced body weight gain and lipid accumulation in the liver and adipose tissue compared to the HFD control group. Triglyceride (TG), total cholesterol, and low-density lipoprotein-cholesterol levels in serum were decreased by GWBR supplementation, whereas high-density lipoprotein-cholesterol level significantly increased. In addition, mRNA levels of transcriptional factors, such as peroxisome proliferator-activated receptor-γ, CCAAT enhancer-binding protein (C/EBP)-α, C/EBP-β, sterol regulatory element-binding protein-1c, and related genes, including adipocyte fatty acid-binding protein, fatty acid synthase, and lipoprotein lipase, were significantly lower in the GWBR groups. However, lipolytic enzymes, such as hormone-sensitive lipase, adipose TG lipase, and carnitine palmitoyltransferase-1, and uncoupling protein 2 mRNA levels were significantly higher in GWBR-supplemented mice. These results suggest that GWBR exerts antiobesity effects by decreasing lipid accumulation and promoting lipolysis in HFD-induced obese mice. PMID:27022689

  19. High-gain harmonic generation of soft X-rays with the `fresh bunch` technique

    SciTech Connect

    Yu, Li-Hua; Ben-Zvi, I.

    1996-10-01

    We report numerical simulations (using the TDA code) and analytic verification of the generation of 64 {Angstrom} high power soft X- rays from an exponential regime single pass seeded FEL. The seed is generated in the FEL using the High Gain Harmonic Generation (HGHG) technique combined with the `Fresh bunch` technique. A seed pulse at 2944 {Angstrom} is generated by conventional laser techniques. The seed pulse produces an intense energy modulation of the rear part of a I GeV, 1245 {Angstrom} electron beam in a `modulator` wiggler. In the `radiator` wiggler, (resonant to 64 {Angstrom}), the energy modulation creates beam density modulation followed by radiation of the 46{sup th} harmonic of the seed. We use a magnetic delay to position the 64 A{Angstrom} radiation at the undisturbed front of the bunch to serve as a seed for a single pass, exponential growth FEL. After a 9 m long exponential section followed by a 7 m long tapered section the radiation power reaches 3.3 GW.

  20. Studies of relative gain and timing response of fine-mesh photomultiplier tubes in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Sulkosky, V.; Allison, L.; Barber, C.; Cao, T.; Ilieva, Y.; Jin, K.; Kalicy, G.; Park, K.; Ton, N.; Zheng, X.

    2016-08-01

    We investigated the use of Hamamatsu fine-mesh photomultiplier tube assemblies H6152-70 and H6614-70 with regard to their gain and timing resolution in magnetic fields up to 1.9 T. Our results show that the H6614-70 assembly can operate reliably in magnetic fields exceeding 1.5 T, while preserving a reasonable timing resolution even with a gain reduction of a factor of ≈100. The reduction of the relative gain of the H6152-70 is similar to the H6614-70's near 1.5 T, but its timing resolution worsens considerably at this high field.

  1. The Relationship between Self-Esteem and Academic Achievement in a Group of High, Medium, and Low Secondary Public High School Achievers.

    ERIC Educational Resources Information Center

    Thomas-Brantley, Betty J.

    This study investigated the relationship between self-esteem and academic achievement in a group of 150 high, medium, and low achievers at a large midwestern public high school. Correlating data from the Coopersmith Inventory of self-esteem with grades, cumulative grade point averages, and class rank, the study disclosed a positive correlation…

  2. Lean rats gained more body weight than obese ones from a high-fibre diet.

    PubMed

    Li, Shaoting; Zhang, Cheng; Gu, Yingyi; Chen, Long; Ou, Shiyi; Wang, Yong; Peng, Xichun

    2015-10-28

    There is controversy over previous findings that a high ratio of Firmicutes to Bacteriodetes helps obese animals harvest energy from the diet. To further investigate the relationship between microbial composition and energy harvest, microbial adaptation to diet and time should be considered. In this study, lean and obese rats were successfully induced with low-fat and high-fat diets. An 8-week high soyabean fibre (HSF)-containing diet was then fed to investigate the interaction between the diet and the rats' gut microbiota, as well as their influence on rats' growth. Rats' body weight (BW) was recorded weekly; their plasma lipids and their gut microbiota at week 11, 15 and 19 were analysed. After the consumption of the HSF diet, BW of lean rats increased significantly (P<0·05), but no significant alteration in BW was found in obese rats. The average content of plasma cholesterol was lowered and that of TAG was upgraded in both the groups when fed the HSF diet. There was no significant difference observed at each period between lean and obese rats. In the group of lean rats, the diversity of gut microbiota was elevated strongly (P<0·01), and bacteria from phylum Firmicutes and Bacteroidetes were both increased largely (P<0·01); however, the bacterial diversity and composition in obese rats were less altered after the HSF diet control. In conclusion, the increased Firmicutes and Bacteriodetes might relate to lean rats' higher BW gain; 'obese microbiota' could not help the hosts harvest more energy from the HSF diet. PMID:26316354

  3. What's Past Is Prologue: Relations between Early Mathematics Knowledge and High School Achievement

    ERIC Educational Resources Information Center

    Watts, Tyler W.; Duncan, Greg J.; Siegler, Robert S.; Davis-Kean, Pamela E.

    2014-01-01

    Although previous research has established the association between early-grade mathematics knowledge and later mathematics achievement, few studies have measured mathematical skills prior to school entry, and few have investigated the predictive power of early gains in mathematics ability. The current paper relates mathematical skills measured at…

  4. The Relationship of Grade Span in 9th Grade to Math Achievement in High School

    ERIC Educational Resources Information Center

    West, John; Miller, Mary Lou; Myers, Jim; Norton, Timothy

    2015-01-01

    Purpose, Scope, and Method of Study: The purpose of this study was to determine if a correlation exists between grade span for ninth grade and gains in math achievement test scores in 10th grade and 12th grade. A quantitative, longitudinal, correlational research design was employed to investigate the research questions. The population was high…

  5. A Modified Lunar Reconnaissance Orbiter (LRO) High Gain Antenna (HGA) Controller Based on Flight Performance

    NASA Technical Reports Server (NTRS)

    Shah, Neerav

    2010-01-01

    The National Aeronautics and Space Administration's (NASA) Lunar Reconnaissance Orbiter (LRO) was launched on June 18, 2009 and is currently in a 50 km mean altitude polar orbit around the Moon. LRO was designed and built by the NASA Goddard Space Flight Center in Greenbelt, MD. The spacecraft is three-axis stabilized via the attitude control system (ACS), which is composed of various control modes using different sets of sensors and actuators. In addition to pointing the spacecraft, the ACS is responsible for pointing LRO s two appendages, the Solar Array (SA) and the High Gain Antenna (HGA). This study reviews LRO s HGA control system. Starting with an overview of the HGA system, the paper delves into the single input single output (SISO) linear analysis followed by the controller design. Based on flight results, an alternate control scheme is devised to address inherent features in the flight control system. The modified control scheme couples the HGA loop with the spacecraft pointing control loop, and through analysis is shown to be stable and improve transient performance. Although proposed, the LRO project decided against implementing this modification.

  6. Spacecraft Angular Rates Estimation with Gyrowheel Based on Extended High Gain Observer

    PubMed Central

    Liu, Xiaokun; Yao, Yu; Ma, Kemao; Zhao, Hui; He, Fenghua

    2016-01-01

    A gyrowheel (GW) is a kind of electronic electric-mechanical servo system, which can be applied to a spacecraft attitude control system (ACS) as both an actuator and a sensor simultaneously. In order to solve the problem of two-dimensional spacecraft angular rate sensing as a GW outputting three-dimensional control torque, this paper proposed a method of an extended high gain observer (EHGO) with the derived GW mathematical model to implement the spacecraft angular rate estimation when the GW rotor is working at large angles. For this purpose, the GW dynamic equation is firstly derived with the second kind Lagrange method, and the relationship between the measurable and unmeasurable variables is built. Then, the EHGO is designed to estimate and calculate spacecraft angular rates with the GW, and the stability of the designed EHGO is proven by the Lyapunov function. Moreover, considering the engineering application, the effect of measurement noise in the tilt angle sensors on the estimation accuracy of the EHGO is analyzed. Finally, the numerical simulation is performed to illustrate the validity of the method proposed in this paper. PMID:27089347

  7. Spacecraft Angular Rates Estimation with Gyrowheel Based on Extended High Gain Observer.

    PubMed

    Liu, Xiaokun; Yao, Yu; Ma, Kemao; Zhao, Hui; He, Fenghua

    2016-01-01

    A gyrowheel (GW) is a kind of electronic electric-mechanical servo system, which can be applied to a spacecraft attitude control system (ACS) as both an actuator and a sensor simultaneously. In order to solve the problem of two-dimensional spacecraft angular rate sensing as a GW outputting three-dimensional control torque, this paper proposed a method of an extended high gain observer (EHGO) with the derived GW mathematical model to implement the spacecraft angular rate estimation when the GW rotor is working at large angles. For this purpose, the GW dynamic equation is firstly derived with the second kind Lagrange method, and the relationship between the measurable and unmeasurable variables is built. Then, the EHGO is designed to estimate and calculate spacecraft angular rates with the GW, and the stability of the designed EHGO is proven by the Lyapunov function. Moreover, considering the engineering application, the effect of measurement noise in the tilt angle sensors on the estimation accuracy of the EHGO is analyzed. Finally, the numerical simulation is performed to illustrate the validity of the method proposed in this paper. PMID:27089347

  8. Progress towards a high-gain and robust target design for heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Henestroza, Enrique; Grant Logan, B.

    2012-07-01

    Recently [E. Henestroza et al., Phys. Plasmas 18, 032702 (2011)], a new inertial-fusion target configuration, the X-target, using one-sided axial illumination has been explored. This class of target uses annular and solid-profile heavy ion beams to compress and ignite deuterium-tritium (DT) fuel that fills the interior of metal cases that have side-view cross sections in the shape of an "X." X-targets using all-DT-filled metal cases imploded by three annular ion beams resulted in fuel densities of ˜50 g/cm3 at peak compression, and fusion gains of ˜50, comparable to heavy ion driven hohlraum targets [D. A. Callahan-Miller and M. Tabak, Phys. Plasmas 7, 2083 (2000)]. This paper discusses updated X-target configurations that incorporate inside the case a propellant (plastic) and a pusher (aluminum) surrounding the DT fuel. The updated configurations are capable of assembling higher fuel areal densities ˜2 g/cm2 using two annular beams to implode the target to peak DT densities ˜100 g/cm3, followed by a fast-ignition solid ion beam which heats the high-density fuel to thermonuclear temperatures in ˜200 ps to start the burn propagation, obtaining gains of ˜300. These targets have been modeled using the radiation-hydrodynamics code HYDRA [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] in two- and three- dimensions to study the properties of the implosion as well as the ignition and burn propagation phases. At typical Eulerian mesh resolutions of a few microns, the aluminum-DT interface shows negligible Rayleigh-Taylor (RT) and Richtmyer-Meshkov instability growth; also, the shear flow of the DT fuel as it slides along the metal X-target walls, which drives the RT and Kelvin Helmholtz instabilities, does not have a major effect on the burning rate. An analytic estimate of the RT instability process at the Al-DT interface shows that the aluminum spikes generated during the pusher deceleration phase would not reach the ignition zone in time to affect the burning

  9. Progress towards a high-gain and robust target design for heavy ion fusion

    SciTech Connect

    Henestroza, Enrique; Grant Logan, B.

    2012-07-15

    Recently [E. Henestroza et al., Phys. Plasmas 18, 032702 (2011)], a new inertial-fusion target configuration, the X-target, using one-sided axial illumination has been explored. This class of target uses annular and solid-profile heavy ion beams to compress and ignite deuterium-tritium (DT) fuel that fills the interior of metal cases that have side-view cross sections in the shape of an 'X.' X-targets using all-DT-filled metal cases imploded by three annular ion beams resulted in fuel densities of {approx}50 g/cm{sup 3} at peak compression, and fusion gains of {approx}50, comparable to heavy ion driven hohlraum targets [D. A. Callahan-Miller and M. Tabak, Phys. Plasmas 7, 2083 (2000)]. This paper discusses updated X-target configurations that incorporate inside the case a propellant (plastic) and a pusher (aluminum) surrounding the DT fuel. The updated configurations are capable of assembling higher fuel areal densities {approx}2 g/cm{sup 2} using two annular beams to implode the target to peak DT densities {approx}100 g/cm{sup 3}, followed by a fast-ignition solid ion beam which heats the high-density fuel to thermonuclear temperatures in {approx}200 ps to start the burn propagation, obtaining gains of {approx}300. These targets have been modeled using the radiation-hydrodynamics code HYDRA [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] in two- and three- dimensions to study the properties of the implosion as well as the ignition and burn propagation phases. At typical Eulerian mesh resolutions of a few microns, the aluminum-DT interface shows negligible Rayleigh-Taylor (RT) and Richtmyer-Meshkov instability growth; also, the shear flow of the DT fuel as it slides along the metal X-target walls, which drives the RT and Kelvin Helmholtz instabilities, does not have a major effect on the burning rate. An analytic estimate of the RT instability process at the Al-DT interface shows that the aluminum spikes generated during the pusher deceleration phase would not

  10. Laser diode-pumped dual-cavity high-power fiber laser emitting at 1150  nm employing hybrid gain.

    PubMed

    Chen, Yizhu; Xiao, Hu; Xu, Jiangming; Leng, Jinyong; Zhou, Pu

    2016-05-10

    We demonstrate a laser diode-pumped dual-cavity high-power fiber laser emitting at 1150 nm. The laser employs Yb and Raman gains simultaneously. The fiber laser with a simple structure achieves high-efficiency operation while efficiently suppressing the amplified spontaneous emission and parasitic oscillation. The maximum output power at 1150 nm is 110.8 W, with an optical-to-optical efficiency of 57%. Further power scaling at 1150 nm is expected with the optimization of the system design. PMID:27168299

  11. Examining Organizational Practices That Predict Persistence among High-Achieving Black Males in High School

    ERIC Educational Resources Information Center

    Anderson, Kenneth Alonzo

    2016-01-01

    Background/Context: This article summarizes an increasing trend of antideficit Black male research in mathematics and highlights opportunities to add to the research. A review of the literature shows that antideficit researchers often examine relationships between individual traits and persistence of high-achieving Black males in mathematics.…

  12. Relationships among Stress, Coping, and Mental Health in High-Achieving High School Students

    ERIC Educational Resources Information Center

    Suldo, Shannon M.; Shaunessy, Elizabeth; Hardesty, Robin

    2008-01-01

    This study investigates the relationships among stress, coping, and mental health in 139 students participating in an International Baccalaureate (IB) high school diploma program. Mental health was assessed using both positive indicators (life satisfaction, academic achievement, academic self-efficacy) and negative indicators (psychopathology) of…

  13. The Strengths of High-Achieving Black High School Students in a Racially Diverse Setting

    ERIC Educational Resources Information Center

    Marsh, Kris; Chaney, Cassandra; Jones, Derrick

    2012-01-01

    Robert Hill (1972) identified strengths of Black families: strong kinship bonds, strong work orientation, adaptability of family roles, high achievement orientation, and religious orientation. Some suggest these strengths sustain the physical, emotional, social, and spiritual needs of Blacks. This study used narratives and survey data from a…

  14. Relationship between High School Mathematical Achievement and Quantitative GPA

    ERIC Educational Resources Information Center

    Brown, Jennifer L.; Halpin, Glennelle; Halpin, Gerald

    2015-01-01

    The demand for STEM graduates has increased, but the number of incoming freshmen who declare a STEM major has remained stagnant. High school courses, such as calculus, can open or close the gate for students interested in careers in STEM. The purpose of this study was to determine if high school mathematics preparation was a significant…

  15. Gain media edge treatment to suppress amplified spontaneous emission in a high power laser

    DOEpatents

    Hackel, Lloyd A.; Soules, Thomas F.; Fochs, Scott N.; Rotter, Mark D.; Letts, Stephan A.

    2011-02-22

    A novel method and apparatus for suppressing ASE and/or parasitic oscillation modes in a laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges to a predetermined electromagnetic absorbing material arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE, parasitic oscillation modes and/or residual pump energy can be effectively suppressed.

  16. Practically Perfect in Every Way: Can Reframing Perfectionism for High-Achieving Undergraduates Impact Academic Resilience?

    ERIC Educational Resources Information Center

    Dickinson, Mary J.; Dickinson, David A. G.

    2015-01-01

    This study focuses on a pan-disciplinary scheme that targeted high-achieving undergraduate students. Earlier research from the scheme argued that high achievers have discernibly different learning and personal development support needs. One of the most frequent self-reported challenges within this high-achieving group is perfectionism. This…

  17. The Relationship to Achievement on the California High School Exit Exam for Language Minority Students.

    ERIC Educational Resources Information Center

    Garcia, Paul A.; Gopal, Malati

    2003-01-01

    Examines first year results of the California High School Exit Exam (CAHSEE) required for students to earn a high school diploma. Results suggest this high stakes test failed to meet legislative objectives to increase achievement and close the achievement gap. Instead, language-minority students with passing scores achieved significantly below…

  18. Design and performance of an Automatic Gain Control system for the High Energy X-Ray Timing Experiment

    NASA Technical Reports Server (NTRS)

    Pelling, Michael R.; Rothschild, Richard E.; Macdonald, Daniel R.; Hertel, Robert; Nishiie, Edward

    1991-01-01

    The High Energy X-Ray Timing Experiment (HEXTE), currently under development for the X-Ray Timing Explorer (XTE) mission, employs a closed loop gain control system to attain 0.5 percent stabilization of each of eight-phoswich detector gains. This Automatic Gain Control (AGC) system utilizes a split window discriminator scheme to control the response of each detector pulse height analyzer to gated Am-241 X-ray events at 60 keV. A prototype AGC system has been implemented and tested within the gain perturbation environment expected to be experienced by the HEXTE instrument in flight. The AGC system and test configuration are described. Response, stability and noise characteristics are measured and compared with theoretical predictions. The system is found to be generally suitable for the HEXTE application.

  19. Gender, Student Motivation and Academic Achievement in a Midsized Wisconsin High School

    ERIC Educational Resources Information Center

    Lutzke, Steven Ronald

    2013-01-01

    This mixed-methods study investigated relationships among gender, academic motivation and achievement in a mid-sized Wisconsin high school. A questionnaire was developed that focused on perceived ability, achievement motives and achievement goals. Interviews with teachers focused on relationships among academic motivation and gender achievement.…

  20. The Use of Congruence between the Items in a Norm-referenced Test and the Content in Compensatory Education Curricula in the Evaluation of Achievement Gains.

    ERIC Educational Resources Information Center

    Tenenbaum, Arlene Bonnie; Miller, Christine A.

    In the evaluation of Project Information Packages (PIPs), a content analysis was performed to detect congruence between items in a norm-referenced test and the content in six exemplary compensatory education program curricula. Gains on congruent items were used to assess the effectiveness of the programs. Preliminary results show that the amount…

  1. Achieving high CRI from warm to super white

    NASA Astrophysics Data System (ADS)

    Bailey, Edward; Tormey, Ellen S.

    2007-09-01

    Light sources which produce a high color rendering index (CRI) have many applications in the lighting industry today. High color rendering accents the rich color which abounds in nature, interior design, theatrical costumes and props, clothing and fabric, jewelry, and machine vision applications. Multi-wavelength LED sources can pump phosphors at multiple stokes shift emission regimes and when combined with selected direct emission sources can allow for greater flexibility in the production of warm-white and cool white light of specialty interest. Unique solutions to R8 and R14 CRI >95 at 2850K, 4750K, 5250K, and 6750K presented.

  2. Impact of learning orientation on African American children's attitudes toward high-achieving peers.

    PubMed

    Marryshow, Derrick; Hurley, Eric A; Allen, Brenda A; Tyler, Kenneth M; Boykin, A Wade

    2005-01-01

    This study examined Ogbu's widely accepted thesis that African American students reject high academic achievement because they perceive its limited utility in a world where their upward mobility is constrained by racial discrimination. Boykin's psychosocial integrity model contends that Black students value high achievement but that discrepancies between their formative cultural experiences and those imposed in school lead them to reject the modes of achievement available in classrooms. Ninety Black children completed a measure of attitudes toward students who achieve via mainstream or African American cultural values. Participants rejected the mainstream achievers and embraced the African American cultural achievers. Moreover, they expected their teachers to embrace the mainstream achievers and reject those who achieved through high-verve behavior. Results suggest that Boykin's thesis is a needed refinement to Ogbu's ideas. They indicate that Black children may reject not high achievement but some of the mainstream cultural values and behaviors on which success in mainstream classrooms is made contingent. PMID:16402748

  3. Verification of the Solar Dynamics Observatory High Gain Antenna Pointing Algorithm Using Flight Data

    NASA Technical Reports Server (NTRS)

    Bourkland, Kristin L.; Liu, Kuo-Chia

    2011-01-01

    The Solar Dynamics Observatory (SDO), launched in 2010, is a NASA-designed spacecraft built to study the Sun. SDO has tight pointing requirements and instruments that are sensitive to spacecraft jitter. Two High Gain Antennas (HGAs) are used to continuously send science data to a dedicated ground station. Preflight analysis showed that jitter resulting from motion of the HGAs was a cause for concern. Three jitter mitigation techniques were developed and implemented to overcome effects of jitter from different sources. These mitigation techniques include: the random step delay, stagger stepping, and the No Step Request (NSR). During the commissioning phase of the mission, a jitter test was performed onboard the spacecraft, in which various sources of jitter were examined to determine their level of effect on the instruments. During the HGA portion of the test, the jitter amplitudes from the single step of a gimbal were examined, as well as the amplitudes due to the execution of various gimbal rates. The jitter levels were compared with the gimbal jitter allocations for each instrument. The decision was made to consider implementing two of the jitter mitigating techniques on board the spacecraft: stagger stepping and the NSR. Flight data with and without jitter mitigation enabled was examined, and it is shown in this paper that HGA tracking is not negatively impacted with the addition of the jitter mitigation techniques. Additionally, the individual gimbal steps were examined, and it was confirmed that the stagger stepping and NSRs worked as designed. An Image Quality Test was performed to determine the amount of cumulative jitter from the reaction wheels, HGAs, and instruments during various combinations of typical operations. The HGA-induced jitter on the instruments is well within the jitter requirement when the stagger step and NSR mitigation options are enabled.

  4. Technology's Achilles Heel: Achieving High-Quality Implementation

    ERIC Educational Resources Information Center

    Hall, Gene E.

    2010-01-01

    An inherent characteristic of technology education is the continual development of new technologies and creating innovative applications of already existing technologies. As exciting as these innovations can be, technology educators and school staffs are frequently challenged to accomplish high levels of implementation. The metaphor of the…

  5. Vocational Interests of Intellectually Gifted and Highly Achieving Young Adults

    ERIC Educational Resources Information Center

    Vock, Miriam; Koller, Olaf; Nagy, Gabriel

    2013-01-01

    Background: Vocational interests play a central role in the vocational decision-making process and are decisive for the later job satisfaction and vocational success. Based on Ackerman's (1996) notion of "trait complexes," specific interest profiles of gifted high-school graduates can be expected. Aims: Vocational interests of gifted and highly…

  6. Academic Dishonesty among Gifted and High-Achieving Students

    ERIC Educational Resources Information Center

    Geddes, Kimberly A.

    2011-01-01

    Gifted high school students are essentially absent in the research concerning academic integrity; however, over the past few years, educators of gifted students have noticed an increase in the occurrences of academic dishonesty among students in gifted classrooms (Abilock, 2009). This research may be analyzed to provide some insight into the…

  7. Student Achievement Data Systems in High and Low Performing Schools

    ERIC Educational Resources Information Center

    Stachowiak, Jeannie E.

    2013-01-01

    The purpose of this study was to determine if there was a difference in how high and low performing elementary school districts use and analyze data to differentiate instruction, make changes to district/grade level curriculum, determine professional development needs, determine teacher effectiveness, and determine the use of school district…

  8. Community Schools Seek to Improve High School Achievement, College Readiness

    ERIC Educational Resources Information Center

    Gilroy, Marilyn

    2011-01-01

    The Coalition for Community Schools, an alliance of more than 150 national, state, and local organizations, is bringing public schools in partnership with community resources to improve student success. While that might seem like an abstract idea, it has very concrete goals, such as boosting high school graduation rates and college readiness.…

  9. Scientific Reasoning and Achievement in a High School English Course.

    ERIC Educational Resources Information Center

    Kral, E. A.

    1997-01-01

    A Piagetian-based, systematic instructional theory developed by A. E. Lawson was used as a reasoning model in a 12th-grade English course at Grand Island Senior High in Grand Island, Nebraska, from 1982 to 1991. The thinking patterns that comprised the hypothetical-deductive stage of human intellectual development used in the course were…

  10. Common Core and America's High-Achieving Students

    ERIC Educational Resources Information Center

    Plucker, Jonathan A.

    2015-01-01

    While the merit and politics of the Common Core State Standards (CCSS) have been much debated and discussed, one topic has been virtually ignored: What do the standards portend for America's high-ability students? This brief addresses that question and provides guidance for CCSS-implementing districts and schools as they seek to help these…

  11. Achieving High Performance with FPGA-Based Computing

    PubMed Central

    Herbordt, Martin C.; VanCourt, Tom; Gu, Yongfeng; Sukhwani, Bharat; Conti, Al; Model, Josh; DiSabello, Doug

    2011-01-01

    Numerous application areas, including bioinformatics and computational biology, demand increasing amounts of processing capability. In many cases, the computation cores and data types are suited to field-programmable gate arrays. The challenge is identifying the design techniques that can extract high performance potential from the FPGA fabric. PMID:21603088

  12. Organizational Citizenship of Faculty and Achievement of High School Students

    ERIC Educational Resources Information Center

    DiPaola, Michael F.; Hoy, Wayne K.

    2005-01-01

    All successful organizations, including successful high schools, have employees who go beyond their formal job responsibilities and freely give of their time and energy to succeed. Organ was the first to use the phrase "organizational citizenship behavior" (OCB) to denote organizationally beneficial behavior of workers that was not prescribed but…

  13. High-Achieving Schools Put Equity Front and Center

    ERIC Educational Resources Information Center

    Gleason, Sonia Caus; Gerzon, Nancy

    2014-01-01

    How does professional learning look and feel in high-poverty schools where every student makes at least one year's worth of progress every year? How do schools and leaders put all the varied components of professional learning together so that they support all students learning every day? What professional learning grounds and sustains…

  14. Principals’ Perception of Influence on Factors Affecting Student Achievement in Low- and High-Achieving Urban High Schools

    ERIC Educational Resources Information Center

    Bloom, Collette M.; Owens, Emiel W.

    2013-01-01

    The purpose of the study was to compare and contrast influences principals have on staffing, curriculum issues, and discipline policies in high- and low-performing urban high schools. The data for the present study were drawn from the first year follow up of the Educational Longitudinal Survey of 2002-2004 (ELS: 02), administered by the National…

  15. Achieving High Reliability Operations Through Multi-Program Integration

    SciTech Connect

    Holly M. Ashley; Ronald K. Farris; Robert E. Richards

    2009-04-01

    Over the last 20 years the Idaho National Laboratory (INL) has adopted a number of operations and safety-related programs which has each periodically taken its turn in the limelight. As new programs have come along there has been natural competition for resources, focus and commitment. In the last few years, the INL has made real progress in integrating all these programs and are starting to realize important synergies. Contributing to this integration are both collaborative individuals and an emerging shared vision and goal of the INL fully maturing in its high reliability operations. This goal is so powerful because the concept of high reliability operations (and the resulting organizations) is a masterful amalgam and orchestrator of the best of all the participating programs (i.e. conduct of operations, behavior based safety, human performance, voluntary protection, quality assurance, and integrated safety management). This paper is a brief recounting of the lessons learned, thus far, at the INL in bringing previously competing programs into harmony under the goal (umbrella) of seeking to perform regularly as a high reliability organization. In addition to a brief diagram-illustrated historical review, the authors will share the INL’s primary successes (things already effectively stopped or started) and the gaps yet to be bridged.

  16. Telescoping Solar Array Concept for Achieving High Packaging Efficiency

    NASA Technical Reports Server (NTRS)

    Mikulas, Martin; Pappa, Richard; Warren, Jay; Rose, Geoff

    2015-01-01

    Lightweight, high-efficiency solar arrays are required for future deep space missions using high-power Solar Electric Propulsion (SEP). Structural performance metrics for state-of-the art 30-50 kW flexible blanket arrays recently demonstrated in ground tests are approximately 40 kW/cu m packaging efficiency, 150 W/kg specific power, 0.1 Hz deployed stiffness, and 0.2 g deployed strength. Much larger arrays with up to a megawatt or more of power and improved packaging and specific power are of interest to mission planners for minimizing launch and life cycle costs of Mars exploration. A new concept referred to as the Compact Telescoping Array (CTA) with 60 kW/cu m packaging efficiency at 1 MW of power is described herein. Performance metrics as a function of array size and corresponding power level are derived analytically and validated by finite element analysis. Feasible CTA packaging and deployment approaches are also described. The CTA was developed, in part, to serve as a NASA reference solar array concept against which other proposed designs of 50-1000 kW arrays for future high-power SEP missions could be compared.

  17. Efforts toward achieving an unmanned, high-altitude LTA platform

    SciTech Connect

    Onda, Masahiko; Ford, M.L.

    1996-10-01

    The modern demands for an unmanned aerospace platform, capable of long-duration stationkeeping at high-altitudes, are well-known. Satellites, balloons, and aircraft have traditionally served in the role of platform, facilitating tasks ranging from telecommunications to deep-space astronomy. However, limitations on the performance and flexibility of these systems, as well as the intrinsically high-cost of satellite construction, operation, and repair, warrants development of a supplemental technology for the platform. Much has been written in the literature on the possible advantages of a lighter-than-air (LTA) platform, if such an LTA could be constructed. Potential applications include remote sensing, environmental monitoring, mobile communications, space and polar observations, cargo delivery, military reconnaissance, and others. At present, conventional LTA`s are not capable of serving in the manner specified. Within this context, a research program known as HALROP (High Altitude Long Range Observational Platform) is currently underway. The goal is to create a stratospheric platform, possibly in the form of a next generation LTA vehicle. The authors present a qualitative review of their efforts, focusing on milestones in the HALROP Program. 12 refs., 6 figs., 2 tabs.

  18. Liver Fatty Acid Binding Protein Gene-ablation Exacerbates Weight Gain in High-Fat Fed Female Mice

    PubMed Central

    McIntosh, Avery L.; Atshaves, Barbara P.; Landrock, Danilo; Landrock, Kerstin K.; Martin, Gregory G.; Storey, Stephen M.; Kier, Ann B.; Schroeder, Friedhelm

    2013-01-01

    Loss of liver fatty acid binding protein (L-FABP) decreases long chain fatty acid uptake and oxidation in primary hepatocytes and in vivo. On this basis, L-FABP gene ablation would potentiate high-fat diet-induced weight gain and weight gain/energy intake. While this was indeed the case when L-FABP null (−/−) mice on the C57BL/6NCr background were pair-fed high fat diet, whether this would also be observed under high-fat diet fed ad libitum was not known. Therefore, this possibility was examined in female L-FABP (−/−) mice on the same background. L-FABP (−/−) mice consumed equal amounts of defined high-fat or isocaloric control diets fed ad libitum. However, on the ad libitum fed high-fat diet the L-FABP (−/−) mice exhibited: 1) Decreased hepatic long chain fatty acid (LCFA) β-oxidation as indicated by lower serum β–hydroxybutyrate level; 2) Decreased hepatic protein levels of key enzymes mitochondrial (rate limiting carnitine palmitoyl acyltransferase A1, CPT1A; HMG-CoA synthase) and peroxisomal (acyl CoA oxidase 1, ACOX1) LCFA β-oxidation; 3) Increased fat tissue mass (FTM) and FTM/energy intake to the greatest extent; and 4) Exacerbated body weight gain, weight gain/energy intake, liver weight, and liver weight/body weight to the greatest extent. Taken together, these findings showed that L-FABP gene-ablation exacerbated diet-induced weight gain and fat tissue mass gain in mice fed high-fat diet ad libitum—consistent with the known biochemistry and cell biology of L-FABP. PMID:23539345

  19. High energy gain in three-dimensional simulations of light sail acceleration

    SciTech Connect

    Sgattoni, A.; Sinigardi, S.; Macchi, A.

    2014-08-25

    The dynamics of radiation pressure acceleration in the relativistic light sail regime are analysed by means of large scale, three-dimensional (3D) particle-in-cell simulations. Differently to other mechanisms, the 3D dynamics leads to faster and higher energy gain than in 1D or 2D geometry. This effect is caused by the local decrease of the target density due to transverse expansion leading to a “lighter sail.” However, the rarefaction of the target leads to an earlier transition to transparency limiting the energy gain. A transverse instability leads to a structured and inhomogeneous ion distribution.

  20. Elementary Principal Leadership Practices, Attitudes, and Self-Efficacy about Teacher Evaluation in Title I Urban Schools Making Gains in Student Achievement

    ERIC Educational Resources Information Center

    Ames, Karen Cohen

    2013-01-01

    Current school reform efforts aim to improve teaching and learning with emphasis on accountability for student achievement. The success of school reform depends on the motivation and capacities of school leaders. It is important to know what effective leadership practices look like to understand the direct impact to student achievement,…

  1. A Preliminary Study of the Relevance of a Standardized Test for Measuring Achievement Gains in Innovative Arithmetic Programs. Project LONGSTEP Final Report. Volume II. Appendix Report.

    ERIC Educational Resources Information Center

    Everett, Bruce E.

    The general emphasis of Project LONGSTEP was on the identification of changes in student achievement that occur as a result of exposure to intensive educational innovation. During the course of the project, questions were raised concerning (1) the relevance of the standardized achievement test utilized in the project to the stated objectives of…

  2. What’s Past is Prologue: Relations Between Early Mathematics Knowledge and High School Achievement

    PubMed Central

    Watts, Tyler W.; Duncan, Greg J.; Siegler, Robert S.; Davis-Kean, Pamela E.

    2015-01-01

    Although previous research has established the association between early-grade mathematics knowledge and later mathematics achievement, few studies have measured mathematical skills prior to school entry, nor have they investigated the predictive power of early gains in mathematics ability. The current paper relates mathematical skills measured at 54 months to adolescent mathematics achievement using multi-site longitudinal data. We find that preschool mathematics ability predicts mathematics achievement through age 15, even after accounting for early reading, cognitive skills, and family and child characteristics. Moreover, we find that growth in mathematical ability between age 54 months and first grade is an even stronger predictor of adolescent mathematics achievement. These results demonstrate the importance of pre-kindergarten mathematics knowledge and early math learning for later achievement. PMID:26806961

  3. Achieving high data reduction with integral cubic B-splines

    NASA Technical Reports Server (NTRS)

    Chou, Jin J.

    1993-01-01

    During geometry processing, tangent directions at the data points are frequently readily available from the computation process that generates the points. It is desirable to utilize this information to improve the accuracy of curve fitting and to improve data reduction. This paper presents a curve fitting method which utilizes both position and tangent direction data. This method produces G(exp 1) non-rational B-spline curves. From the examples, the method demonstrates very good data reduction rates while maintaining high accuracy in both position and tangent direction.

  4. High Achievement in Mathematics Education in India: A Report from Mumbai

    ERIC Educational Resources Information Center

    Raman, Manya

    2010-01-01

    This paper reports a study aimed at characterizing the conditions that lead to high achievement in mathematics in India. The study involved eight schools in the greater Mumbai region. The main result of the study is that the notion of high achievement itself is problematic, as reflected in the reports about mathematics achievement within and…

  5. The Relationship between Parental Involvement and Student Achievement in a Rural Florida High School

    ERIC Educational Resources Information Center

    Jackson, Willie A.

    2011-01-01

    Parental involvement is viewed as critical to the development of effective schools and student achievement. The relationship between parental involvement and achievement test scores at a rural high school in Florida was not known. This high school has not met the state standards as determined by the Florida Comprehensive Achievement Test (FCAT)…

  6. Modelling Plant and Soil Nitrogen Feedbacks Affecting Forest Carbon Gain at High CO2

    NASA Astrophysics Data System (ADS)

    McMurtrie, R. E.; Norby, R. J.; Franklin, O.; Pepper, D. A.

    2007-12-01

    Short-term, direct effects of elevated atmospheric CO2 concentrations on plant carbon gain are relatively well understood. There is considerable uncertainty, however, about longer-term effects, which are influenced by various plant and ecosystem feedbacks. A key feedback in terrestrial ecosystems occurs through changes in plant carbon (C) allocation patterns. For instance, if high CO2 were to increase C allocation to roots, then plants may experience positive feedback through improved plant nutrition. A second type of feedback, associated with decomposition of soil-organic matter, may reduce soil-nutrient availability at high CO2. This paper will consider mechanistic models of both feedbacks. Effects of high CO2 on plant C allocation will be investigated using a simple model of forest net primary production (NPP) that incorporates the primary mechanisms of plant carbon and nitrogen (N) balance. The model called MATE (Model Any Terrestrial Ecosystem) includes an equation for annual C balance that depends on light- saturated photosynthetic rate and therefore on [CO2], and an equation for N balance incorporating an expression for N uptake as a function of root mass. The C-N model is applied to a Free Air CO2 Exchange (FACE) experiment at Oak Ridge National Laboratory (ORNL) in Tennessee, USA, where closed-canopy, monoculture stands of the deciduous hardwood sweetgum ( Liquidambar styraciflua) have been growing at [CO2] of 375 and 550 ppm for ten years. Features of this experiment are that the annual NPP response to elevated CO2 has averaged approximately 25% over seven years, but that annual fine-root production has almost doubled on average, with especially large increases in later years of the experiment (Norby et al. 2006). The model provides a simple graphical approach for analysing effects of elevated CO2 and N supply on leaf/root/wood C allocation and productivity. It simulates increases in NPP and fine-root production at the ORNL FACE site that are consistent

  7. The Linguistic Gains and Acculturation of American High School Students on Exchange Programs in Germany

    ERIC Educational Resources Information Center

    Lovitt, Ashli

    2013-01-01

    There has been a sharp rise in study abroad participation over the last few decades (Institute for International Education, 2011), which can largely be explained by the rise of short-term study abroad programs. While there is much to be gained from participation in such programs, mid-length and year programs may offer the greatest benefits for…

  8. High-temporal contrast using low-gain optical parametric amplification

    SciTech Connect

    Shah, Rahul C; Johnson, Randall P; Shimada, Tsutomu; Flippo, Kirk A; Fernandez, Juan C; Hegelich, Bjorn M

    2008-01-01

    We demonstrate the use of low-gain optical parametric amplification (OPA) as a means of improving temporal contrast to a detection-limited level 10{sup -10}. 250 {mu}J, 500 fs pulses of 1053 nm are frequency doubled and subsequently restored to the original wavelength by OPA with >10% efficiency.

  9. Rectangular Dielectric-loaded Structures for Achieving High Acceleration Gradients

    SciTech Connect

    Wang Changbiao; Yakovlev, V. P.; Marshall, T. C.; LaPointe, M. A.; Hirshfield, J. L.

    2006-11-27

    Rectangular dielectric-loaded structures are described that may sustain higher acceleration gradients than conventional all-metal structures with similar apertures. One structure is a test cavity designed to ascertain the breakdown limits of dielectrics, while a second structure could be the basis for a two-beam accelerator. CVD diamond is an attractive dielectric for a high-gradient structure, since the published DC breakdown limit for CVD diamond is {approx} 2 GV/m, although the limit has never been determined for RF fields. Here we present a design of a diamond-lined test cavity to measure the breakdown limit. The designed cavity operates at 34 GHz, where with 10-MW input power it is expected to produce an {approx}800 MV/m field on the diamond surface - provided breakdown is avoided. The two channel rectangular dielectric-loaded waveguide could be a two-beam accelerator structure, in which a drive beam is in one channel and an accelerated beam is in the other. The RF power produced by drive bunches in the drive channel is continuously coupled to the acceleration channel. The ratio of fields in the channels (transformer ratio) for the operating mode can be designed by adjusting the dimensions of the structure. An example of the two-channel structure is described, in which a train of five 3-nC drive bunches excites wake fields in the accelerator channel of up to 1.3 GV/m with a transformer ratio of 10 for the design mode.

  10. A collimated focused ultrasound beam of high acoustic transmission and minimum diffraction achieved by using a lens with subwavelength structures

    SciTech Connect

    Lin, Zhou; Tu, Juan; Cheng, Jianchun; Guo, Xiasheng E-mail: dzhang@nju.edu.cn; Wu, Junru; Huang, Pingtong; Zhang, Dong E-mail: dzhang@nju.edu.cn

    2015-09-14

    An acoustic focusing lens incorporated with periodically aligned subwavelength grooves corrugated on its spherical surface has been developed. It is demonstrated theoretically and experimentally that acoustic focusing achieved by using the lens can suppress the relative side-lobe amplitudes, enhance the focal gain, and minimize the shifting of the focus. Use of the lens coupled with a planar ultrasound transducer can generate an ultrasound beam with enhanced acoustic transmission and collimation effect, which offers the capability of improving the safety, efficiency, and accuracy of targeted surgery implemented by high intensity focused ultrasound.

  11. Optical properties of the output of a high-gain, self-amplified free-electron laser.

    SciTech Connect

    Li, Y.; Lewellen, J.; Huang, Z.; Krinsky, S.; Accelerator Systems Division; BNL

    2004-01-01

    The temporal structure and phase evolutions of a high-gain, self-amplified free-electron laser are measured, including single-shot analysis and statistics over many shots. Excellent agreement with the theory of free-electron laser and photon statistics is found.

  12. Multi-level quantum electrodynamic calculation of spontaneous emission and small signal gain in high voltage free electron lasers

    NASA Astrophysics Data System (ADS)

    Chang, C. S.; Fluhler, H. U.

    1991-12-01

    Using the Weisskopf-Wigner technique, a self consistent quantum electrodynamic (SCQED) theory of spontaneous emission of radiation and single photon small signal gain is developed for high voltage free electron lasers (FEL). Excellent agreement is obtained simultaneously to our knowledge for the first time between the predictions and the experimental observations for lineshift, linewidth and gain. The SCQED theory predicts lineshift and broadening due to quantum mechanical effects for linear, helical and tapered undulator FELs which are not predicted by the classical/conventional FEL theories, but which have been observed 4,5,18,22,23,45,46. Excellent agreement is obtained between the SCQED theory predicted spontaneous emission spectra and the 1980?81 ACO FEL4,18, ACO Optical Klystron FEL45,46, Stanford 10.6 ?m FEL22 and Stanford 3.4 ?m FEL23 experimental spectra. This agreement is much better than the prediction from the classical/conventional FEL theory which gives errors of many tens of percent. We show that the spontaneous emission spectrum obtained from classical/conventional FEL theories is valid only in the limit of a short undulator containing a small number of periods. The small signal gain derived from the SCQED theory is shown to reduce to Colson's gain formula12,34 in the classical limit. However, the SCQED theory predicts significant reductions in the small signal gain which agree well with the ACO gain data5, and are not predicted well by Colson's formula. Due to the non-neglible finite electron state lifetime, it is discovered that a fundamental physical gain limit exists which is universal to all types of FELs within the limits of the single photon transition scheme considered (i.e. if multiphoton effects are ignored). Finally, the implications of the theoretically obtained results are discussed for practical conditions of experimental interest. It is shown that under practical experimental conditions quantum effects can be quite important in the

  13. High-gain wavelength-selective amplification and cavity ring down spectroscopy in a fluoride glass erbium-doped microsphere.

    PubMed

    Rasoloniaina, A; Trebaol, S; Huet, V; Le Cren, E; Nunzi Conti, G; Serier-Brault, H; Mortier, M; Dumeige, Y; Féron, P

    2012-11-15

    We experimentally demonstrate a compact optical amplifier consisting of a rare-earth-doped whispering-gallery-mode microsphere coupled via a tapered fiber. A gain up to 20 dB is reported in an erbium-doped fluoride glass microsphere 135 μm in diameter. Below the amplification regime, the optical gain is used to compensate for unavoidable losses due to surface contamination or scattering. Quality factor as high as 2×10(9) has been measured by analyzing the transient response of the microsphere excited by a dynamically shifted frequency input signal. PMID:23164896

  14. High Risk of Obesity and Weight Gain for HIV-Infected Uninsured Minorities

    PubMed Central

    Taylor, Barbara S.; Liang, Yuanyuan; Garduño, L. Sergio; Walter, Elizabeth A.; Gerardi, Margit; Anstead, Gregory M.; Bullock, Delia; Turner, Barbara J.

    2014-01-01

    Background Obesity and HIV disproportionately affect minorities and have significant health risks, but few studies have examined disparities in weight change in HIV-seropositive (HIV+) cohorts. Objective To determine racial and health insurance disparities in significant weight gain in a predominately Hispanic HIV+ cohort. Methods Our observational cohort study of 1,214 non-underweight HIV+ adults from 2007-2010 had significant weight gain (≥3% annual BMI increase) as primary outcome. The secondary outcome was continuous BMI over time. A four-level race-ethnicity/insurance predictor reflected the interaction between race-ethnicity and insurance: insured white (non-Hispanic), uninsured white, insured minority (Hispanic or black), or uninsured minority. Logistic and mixed effects models adjusted for: baseline BMI; age; gender; household income; HIV transmission category; antiretroviral therapy type; CD4+ count; plasma HIV-1 RNA; observation months; and visit frequency. Results The cohort was 63% Hispanic and 14% black; 13.3% were insured white, 10.0% uninsured white, 40.9% insured minority, and 35.7% uninsured minority. At baseline, 37.5% were overweight, 22.1% obese. Median observation was 3.25 years. 24.0% had significant weight gain, which was more likely for uninsured minority patients than insured whites (adjusted odds ratio=2.85 , 95%CI: 1.66, 4.90). The rate of BMI increase in mixed effects models was greatest for uninsured minorities. Of 455 overweight at baseline, 29% were projected to become obese in 4 years. Conclusions and Relevance In this majority Hispanic HIV+ cohort, 60% were overweight or obese at baseline, and uninsured minority patients gained weight more rapidly. These data should prompt greater attention by HIV providers to prevention of obesity. PMID:24121754

  15. High Gain, Fast Scan, Broad Spectrum, Parallel Beam Wavelength Dispersive X-ray Spectrometer for SEM

    SciTech Connect

    David OHara; Dr. Eric Lochmer

    2003-09-12

    Parallax Research, Inc. proposes to produce a new type of x-ray spectrometer for use with Scanning Electron Microscopy (SEM) that would have the energy resolution of WDS and the ease of use of EDS with sufficient gain for lower energies that it can be used at low beam currents as is EDS. Parallax proposes to do this by development of new multiple reflection x-ray collimation optics, new diffractor technology, new detector technology and new scan algorithms.

  16. Gain weighted eigenspace assignment

    NASA Technical Reports Server (NTRS)

    Davidson, John B.; Andrisani, Dominick, II

    1994-01-01

    This report presents the development of the gain weighted eigenspace assignment methodology. This provides a designer with a systematic methodology for trading off eigenvector placement versus gain magnitudes, while still maintaining desired closed-loop eigenvalue locations. This is accomplished by forming a cost function composed of a scalar measure of error between desired and achievable eigenvectors and a scalar measure of gain magnitude, determining analytical expressions for the gradients, and solving for the optimal solution by numerical iteration. For this development the scalar measure of gain magnitude is chosen to be a weighted sum of the squares of all the individual elements of the feedback gain matrix. An example is presented to demonstrate the method. In this example, solutions yielding achievable eigenvectors close to the desired eigenvectors are obtained with significant reductions in gain magnitude compared to a solution obtained using a previously developed eigenspace (eigenstructure) assignment method.

  17. Novel Design of a High-gain and Wideband Fabry-Pérot Cavity Antenna Using a Tapered AMC Substrate

    NASA Astrophysics Data System (ADS)

    Yeo, Junho; Kim, Dongho

    2009-03-01

    A high-gain and wideband electromagnetic bandgap (EBG) resonator antenna with a tapered artificial magnetic conductor (AMC) ground plane is presented. The proposed EBG resonator antenna is comprised of a frequency selective surface (FSS) superstrate with a strip dipole array and an AMC ground plane with tapered rectangular patches. The realized gain and the bandwidth of the antenna can be improved simultaneously by using the tapered AMC where the phase difference of the reflected waves from the patches with different length is within 180° and the destructive interference among them can be considerably reduced. The maximum gain is increased about 2˜3 dB and the bandwidth is improved about 2.5 times compared to when the uniform AMC is used.

  18. Dynamics of a gain-switched distributed feedback ridge waveguide laser in nanoseconds time scale under very high current injection conditions.

    PubMed

    Klehr, A; Wenzel, H; Brox, O; Schwertfeger, S; Staske, R; Erbert, G

    2013-02-11

    We present detailed experimental investigations of the temporal, spectral and spatial behavior of a gain-switched distributed feedback (DFB) laser emitting at a wavelength of 1064 nm. Gain-switching is achieved by injecting nearly rectangular shaped current pulses having a length of 50 ns and a very high amplitude up to 2.5 A. The repetition frequency is 200 kHz. The laser has a ridge waveguide (RW) for lateral waveguiding with a ridge width of 3 µm and a cavity length of 1.5 mm. Time resolved investigations show, depending on the amplitude of the current pulses, that the optical power exhibits different types of oscillatory behavior during the pulses, accompanied by changes in the lateral near field intensity profiles and optical spectra. Three different types of instabilities can be distinguished: mode beating with frequencies between 25 GHz and 30 GHz, switching between different lateral intensity profiles with a frequency of 0.4 GHz and self-sustained oscillations with a frequency of 4 GHz. The investigations are of great relevance for the utilization of gain-switched DFB-RW lasers as seed lasers for fiber laser systems and in other applications, which require a high optical power. PMID:23481734

  19. An Examination of Teachers' Effects on High, Middle, and Low Aptitude Students' Performance on a Standardized Achievement Test

    ERIC Educational Resources Information Center

    Good, Thomas L.; Beckerman, Terrill M.

    1978-01-01

    Teacher effectiveness was defined by students' mathematics score on the Iowa Test of Basic Skills while achievement was measured by the Cognitive Abilities Test. Relatively effective teachers generally produced achievement gains from all aptitude levels. Similarly, relatively ineffective teachers did not disproportionately depress achievement for…

  20. Beyond Academic Reputation: Factors that Influence the College of First Choice for High Achieving Students

    ERIC Educational Resources Information Center

    Schoenherr, Holly J.

    2009-01-01

    Studies that have investigated college choice factors for high-achieving students repeatedly cite academic reputation as one of the top indicators of choice but have not indicated why some high-achieving students choose to attend universities with a less prestigious reputation than the more highly prestigious options available to them. The purpose…

  1. The Chinese High School Student's Stress in the School and Academic Achievement

    ERIC Educational Resources Information Center

    Liu, Yangyang; Lu, Zuhong

    2011-01-01

    In a sample of 466 Chinese high school students, we examined the relationships between Chinese high school students' stress in the school and their academic achievements. Regression mixture modelling identified two different classes of the effects of Chinese high school students' stress on their academic achievements. One class contained 87% of…

  2. Does High School Facility Quality Affect Student Achievement? A Two-Level Hierarchical Linear Model

    ERIC Educational Resources Information Center

    Bowers, Alex J.; Urick, Angela

    2011-01-01

    The purpose of this study is to isolate the independent effects of high school facility quality on student achievement using a large, nationally representative U.S. database of student achievement and school facility quality. Prior research on linking school facility quality to student achievement has been mixed. Studies that relate overall…

  3. The Effects of Web-Based/Non-Web-Based Problem-Solving Instruction and High/Low Achievement on Students' Problem-Solving Ability and Biology Achievement

    ERIC Educational Resources Information Center

    Yu, Wen-Feng; She, Hsiao-Ching; Lee, Yu-Mei

    2010-01-01

    This study investigates the effects of two factors: the mode of problem-solving instruction (i.e. Web-based versus non-Web-based) and the level of academic achievement (i.e. high achievers versus low achievers) on students' problem-solving ability and biology achievement. A quasi-experimental design was used, in which the experimental group…

  4. New Schools, Overcrowding Relief, and Achievement Gains in Los Angeles--Strong Returns from a $19.5 Billion Investment. Policy Brief 12-2

    ERIC Educational Resources Information Center

    Welsh, William; Coghlan, Erin; Fuller, Bruce; Dauter, Luke

    2012-01-01

    Aiming to relieve overcrowded schools operating on multiple tracks, the Los Angeles Unified School District (LAUSD) has invested more than $19 billion to build 130 new facilities over the past decade. District leaders asked researchers at Berkeley to estimate the achievement effects of this massive initiative--benefits that may stem from entering…

  5. An Analysis of Java Programming Behaviors, Affect, Perceptions, and Syntax Errors among Low-Achieving, Average, and High-Achieving Novice Programmers

    ERIC Educational Resources Information Center

    Rodrigo, Ma. Mercedes T.; Andallaza, Thor Collin S.; Castro, Francisco Enrique Vicente G.; Armenta, Marc Lester V.; Dy, Thomas T.; Jadud, Matthew C.

    2013-01-01

    In this article we quantitatively and qualitatively analyze a sample of novice programmer compilation log data, exploring whether (or how) low-achieving, average, and high-achieving students vary in their grasp of these introductory concepts. High-achieving students self-reported having the easiest time learning the introductory programming…

  6. High Efficiency Automatic-Power-Controlled and Gain-Clamped EDFA for Broadband Passive Optical Networking Systems

    NASA Astrophysics Data System (ADS)

    Shen, Jyi-Lai; Wei, Shui-Ken; Lin, Chin-Yuan; Iong Li, Ssu; Huang, Chih-Chuan

    2010-04-01

    The configuration of a simple improved high efficiency automatic-power-controlled and gain-clamped EDFA (APC-GC-EDFA) for broadband passive optical networking systems (BPON) is presented here. In order to compensate the phase and amplitude variation due to the different distance between the optical line terminal (OLT) and optical network units (ONU), the APC-GC-EDFA need to be employed. A single 980 nm laser module is employed as the primary pump. To extend the bandwidth, all C-band ASE is recycled as the secondary pump to enhance the gain efficiency. An electrical feedback circuit is used as a multi-wavelength channel transmitter monitor for the automatic power control to improve the gain-flattened flatness for stable amplification. The experimental results prove that the EDFA system can provide flatter clamped gain in both C-band and L-band configurations. The gain flatness wavelength ranging from 1530 to 1610 nm is within 32.83 ± 0.64 dB, i.e. below 1.95 %. The gains are clamped at 33.85 ± 0.65 dB for the input signal power of -40 dBm to -10 dBm. The range of noise figure is between 6.37 and 6.56, which is slightly lower compared to that of unclamped amplifiers. This will be very useful for measuring the gain flatness of APC-GC-EDFA. Finally, we have also demonstrated the records of the overall simultaneous dynamics measurements for the new system stabilization. The carrier to noise ratio (CNR) is 49.5 to 50.8 dBc which is above the National Television System Committee (NTSC) standard of 43 dBc, and both composite second order (CSO) 69.2 to 71.5 dBc and composite triple beat (CTB) of 69.8 to 72.2 dBc are above 53 dBc. The recorded corresponding rise-time of 1.087 ms indicates that the system does not exhibit any overshoot of gain or ASE variation due to the signal at the beginning of the pulse.

  7. Compact high power mid-infrared optical parametric oscillator pumped by a gain-switched fiber laser with "figure-of-h" pulse shape.

    PubMed

    Jiang, Peipei; Chen, Tao; Wu, Bo; Yang, Dingzhong; Hu, Chengzhi; Wu, Pinghui; Shen, Yonghang

    2015-02-01

    We demonstrate a compact high power mid-infrared (MIR) optical parametric oscillator (OPO) pumped by a gain-switched linearly polarized, pulsed fiber laser. The gain-switched fiber laser was constructed with a piece of Yb doped polarization maintaining (PM) fiber, a pair of fiber Bragg gratings written into the matched passive PM fiber and 6 pigtailed pump laser diodes working at 915 nm with 30 W output peak power each. By modulating the pulse width of the pump laser diode, simple pedestal-free pulse shape or pedestal-free trailing pulse shape ("figure-of-h" as we call it) could be achieved from the gain-switched fiber laser. The laser was employed as the pump of a two-channel, periodically poled magnesium oxide lithium niobate-based OPO system. High power MIR emission was generated with average output power of 5.15 W at 3.8 μm channel and 8.54 W at 3.3 μm channel under the highest pump power of 45 W. The corresponding pump-to-idler conversion efficiency was computed to be 11.7% and 19.1%, respectively. Experimental results verify a significant improvement to signal-to-idler conversion efficiency by using "figure-of-h" pulses over simple pedestal-free pulses. Compared to the master oscillator power amplifier (MOPA) fiber laser counterpart, the presented gain switched fiber laser is more attractive in OPO pumping due to its compactness and simplicity which are beneficial to construction of OPO systems for practical MIR applications. PMID:25836126

  8. A High-gain Circularly Polarized Ka-band Microstrip Reflectarray

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1996-01-01

    A half-meter, 32 GHz, circularly polarized microstrip reflectarray antenna has been developed. Excellent efficiency, good bandwidth, and low average sideglobe and cross-pol levels are achieved. It is believed that this is electrically the largest microstrip reflectarray (6924 elements) that has ever been developed, and it is the first time that circular polarization has been demonstrated using microstrip elements.

  9. How Social Emotional Development Skills Gained in High Quality Public School Prekindergarten Impact Kindergarten Academic Readiness

    ERIC Educational Resources Information Center

    Collett, Gale A.

    2013-01-01

    Longitudinal research has demonstrated that children's emotional and social skills are linked to their early academic achievement (Wentzel & Asher, 1995). Children who have difficulty paying attention, following directions, getting along with others, and controlling negative emotions like anger and distress do not do as well in school (Arnokl…

  10. Parent-Child Relations and Psychological Adjustment among High-Achieving Chinese and European American Adolescents

    ERIC Educational Resources Information Center

    Qin, Desiree Baolian; Rak, Eniko; Rana, Meenal; Donnellan, M. Brent

    2012-01-01

    Chinese American students are often perceived as problem-free high achievers. Recent research, however, suggests that high-achieving Chinese American students can experience elevated levels of stress, especially comparing to their peers from other ethnic groups. In this paper, we examine how family dynamics may influence psychological adjustment…

  11. High-Achieving and Average Students' Reading Growth: Contrasting School and Summer Trajectories

    ERIC Educational Resources Information Center

    Rambo-Hernandez, Karen E.; McCoach, D. Betsy

    2015-01-01

    Much is unknown about how initially high-achieving students grow academically, especially given the measurement issues inherent in assessing growth for the highest performing students. This study compared initially high-achieving and average students' growth in reading (in a cohort of third-grade students from 2,000 schools) over 3 years.…

  12. International Note: Between-Domain Relations of Chinese High School Students' Academic Achievements

    ERIC Educational Resources Information Center

    Yangyang, Liu

    2012-01-01

    The present study examined the between-domain relations of Chinese high school students' academic achievements. In a sample of 1870 Chinese 10th grade students, the results indicated that Chinese high school students' academic achievements were correlated across nine subjects. In line with the previous Western findings, the findings suggested that…

  13. The Effect of the Time Management Art on Academic Achievement among High School Students in Jordan

    ERIC Educational Resources Information Center

    Al-Zoubi, Maysoon

    2016-01-01

    This study aimed at recognizing the effect of the Time Management Art on academic achievement among high school students in the Hashemite Kingdom of Jordan. The researcher employed the descriptive-analytic research to achieve the purpose of the study where he chose a sample of (2000) high school female and male students as respondents to the…

  14. A Longitudinal Investigation of Project-Based Instruction and Student Achievement in High School Social Studies

    ERIC Educational Resources Information Center

    Summers, Emily J.; Dickinson, Gail

    2012-01-01

    This longitudinal study focused on how project-based instruction (PBI) influenced secondary social studies students' academic achievement and promoted College and Career Readiness (CCR). We explored and compared student achievement in a PBI high school versus a traditional instruction high school within the same rural school district. While…

  15. Effects of a Collaborative Science Intervention on High Achieving Students' Learning Anxiety and Attitudes toward Science

    ERIC Educational Resources Information Center

    Hong, Zuway-R.

    2010-01-01

    This study investigated the effects of a collaborative science intervention on high achieving students' learning anxiety and attitudes toward science. Thirty-seven eighth-grade high achieving students (16 boys and 21 girls) were selected as an experimental group who joined a 20-week collaborative science intervention, which integrated and utilized…

  16. High repetition rate gain-switched Er:YAG ceramic laser at 1645 nm

    NASA Astrophysics Data System (ADS)

    Chen, B. H.; Zhang, J. N.; Zhao, Y. G.; Zhang, J.; Tang, D. Y.; Shen, D. Y.

    2016-02-01

    We report on a gain-switched Er:YAG ceramic laser resonantly pumped by an acousto-optically modulated Er, Yb co-doped fiber laser at 1532 nm. The laser produced stable pulse trains at 1645 nm with pulse repetition rate tunable between 13-100 kHz and corresponding pulse width of 480-450 ns under a pump power-level of 8.7 W. At the 100 kHz of repetition rate, over 2.2 W of average output power was generated for 6.5 W of incident pump power, corresponding to a slope efficiency of 40% with respect to incident pump power.

  17. High temperature and wavelength dependence of avalanche gain of AlAsSb avalanche photodiodes.

    PubMed

    Sandall, Ian C; Xie, Shiyu; Xie, Jingjing; Tan, Chee Hing

    2011-11-01

    The evolution of the dark currents and breakdown at elevated temperatures of up to 450  K are studied using thin AlAsSb avalanche regions. While the dark currents increase rapidly as the temperature is increased, the avalanche gain is shown to only have a weak temperature dependence. Temperature coefficients of breakdown voltage of 0.93 and 1.93  mV/K were obtained from the diodes of 80 and 230  nm avalanche regions (i-regions), respectively. These values are significantly lower than for other available avalanche materials at these temperatures. The wavelength dependence of multiplication characteristics of AlAsSb p-i-n diodes has also been investigated, and it was found that the ionization coefficients for electrons and holes are comparable within the electric field and wavelength ranges measured. PMID:22048393

  18. High gain-production efficiency and large brightness X-UV laser at Palaiseau

    NASA Astrophysics Data System (ADS)

    Jaeglé, P.; Carillon, A.; Dhez, P.; Goedtkindt, P.; Jamelot, G.; Klisnick, A.; Rus, B.; Zeitoun, Ph.; Jacquemot, S.; Mazataud, D.; Mens, A.; Chauvineau, J. P.

    1995-05-01

    A large gain has been measured for the J=0-1 line of neonlike Zn at λ=21.2 nm. The time evolutions and the localization of emission zones of the J=0-1 and J=2-1 lines are compared. It is shown that a train of very small prepulses before the main pulse has an important role in the J=0=1 emission. A half-cavity has been successfully used to attain a nearly saturated intensity with a 2 cm long plasma. The X-UV pulse energy is of 400 μJ, the laser power of 5 MW. The driving laser is the 0.4 KJ, 600 ps laser of LULI.

  19. High power gain-switched diode laser master oscillator and amplifier

    SciTech Connect

    Poelker, M.

    1995-11-06

    A tapered-stripe, traveling-wave semiconductor optical amplifier was seeded with 3.3 mW of gain-switched diode laser light to obtain over 200 mW average power with pulse widths{approx}105 ps full width at half-maximum (FWHM) and a pulse repetition rate of 499 MHz corresponding to a peak power of 3.8 W. Shorter pulse widths were obtained when the amplifier was driven with less current at the expense of reduced output power. Pulse widths as short as 31 ps FWHM and an average power of 98 mW corresponding to a peak power of 6.3 W were obtained when a different, lower power seed laser was used. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  20. High gain selective amplification in whispering gallery mode resonators: analysis by cavity ring down method

    NASA Astrophysics Data System (ADS)

    Féron, P.; Rasoloniaina, A.; Huet, V.; Le Cren, E.; Trebaol, S.; Nunzi Conti, G.; Serier-Brault, H.; Mortier, M.; Dumeige, Y.

    2013-03-01

    We study both theoretically and experimentally the dispersive properties of single whispering gallery mode resonators. We present a simple experimental protocol which allows us to obtain in detail its coupling regime and thus their dispersive properties. We demonstrate a compact optical amplifier with a gain up to 20dB in an Erbium doped fluoride microsphere of 135μm in diameter coupled via a tapered fiber. The model is also applied to analyze the dynamic behavior of the modal coupling between two degenerate resonances of the same cavity. In particular, this can be used to describe the coupling of counterpropagating whispering gallery modes (WGM) by Rayleigh scattering. The theory is successfully compared to experiments carried out in silica microspheres

  1. Impulse gain and damage from very high dynamic loading using flyer impact

    SciTech Connect

    Osher, J.; Chau, H.; Gerassimenko, M.; Lee, R.; Pomykal, G.; Terhune, R.; Weingart, R.

    1991-07-01

    The Lawrence Livermore National Laboratory (LLNL) 1 MJ and 87 kJ electric guns are in use for a variety of shock-wave applications using the hypervelocity impact of dielectric (or dielectric and metal composite) flyer plates on material samples. The 1 MJ electric gun is a newly completed facility and will be described. The specific applications discussed here include a study of momentum gain and spat damage produced by Kapton flyer impact on aluminium 6061-T6. The experimental impact measurements are used to calibrate code calculations that can be applied under more general hypervelocity impact conditions to typical relative orbital velocities near 10 km/s. The analytical results of code calculations supporting these study areas are also reported.

  2. Manifest Needs of High Ability Achieving and Underachieving Elementary School Children in a Culturally Disadvantaged Setting

    ERIC Educational Resources Information Center

    Masih, Lalit K.

    1974-01-01

    Study samples suggest that the high ability underachiever is characterized by low need for order and higher need to belong to supportive groups; the high ability achiever seems more independent and less attached to his peer group. (Author)

  3. The Meaning High-Achieving African-American Males in an Urban High School Ascribe to Mathematics

    ERIC Educational Resources Information Center

    Thompson, LaTasha; Davis, Julius

    2013-01-01

    Many researchers, educators, administrators, policymakers and members of the general public doubt the prevalence of high-achieving African-American males in urban high schools capable of excelling in mathematics. As part of a larger study, the current study explored the educational experiences of four high-achieving African-American males…

  4. Interplay of the Chirps and Chirped Pulse Compression in a High-gain Seeded Free-electron Laser

    SciTech Connect

    Wu, Juhao; Murphy, J.B.; Emma, P.J.; Wang, X.J.; Watanabe, T.; Zhong, Xinming; /Beijing Normal U.

    2007-01-03

    In a seeded high-gain Free-electron Laser (FEL), where a coherent laser pulse interacts with an ultra-relativistic electron beam, the seed laser pulse can be frequency chirped, and the electron beam can be energy chirped. Besides these two chirps, the FEL interaction introduces an intrinsic frequency chirp in the FEL even if the above mentioned two chirps are absent. In this paper we examine the interplay of these three chirps. The problem is formulated as an initial value problem, and solved via a Green function approach. Besides the chirp evolution, we also give analytical expressions for the pulse duration and bandwidth of the FEL, which remains fully longitudinally coherent in the high gain exponential growth regime. Because the chirps are normally introduced for a final compression of the FEL pulse, some conceptual issues are discussed. We show that in order to get a short pulse duration, an energy chirp in the electron beam is necessary.

  5. High magnetic shear gain in a liquid sodium stable couette flow experiment A prelude to an alpha - omega dynamo

    SciTech Connect

    Colgate, Stirling; Li, Jui; Finn, John; Pariev, Vladimir; Beckley, Howard; Si, Jiahe; Martinic, Joe; Westpfahl, David; Slutz, James; Westrom, Zeb; Klein, Brianna

    2010-11-08

    The {Omega}-phase of the liquid sodium {alpha}-{Omega} dynamo experiment at NMIMT in cooperation with LANL has successfully demonstrated the production of a high toroidal field, B{sub {phi}} {approx_equal} 8 x B{sub r} from the radial component of an applied poloidal magnetic field, B{sub r}. This enhanced toroidal field is produced by rotational shear in stable Couette Row within liquid sodium at Rm {approx_equal} 120. The small turbulence in stable Taylor-Couette Row is caused by Ekman Row where ({delta}v/v){sup 2} {approx} 10{sup -3}. This high {Omega}-gain in low turbulence flow contrasts with a smaller {Omega}-gain in higher turbulence, Helmholtz-unstable shear flows. This result supports the ansatz that large scale astrophysical magnetic fields are created within semi-coherent large scale motions in which turbulence plays a diffusive role that enables magnetic flux linkage.

  6. Achieving and Sustaining New Knowledge Development in High-Expectation Start-Ups

    ERIC Educational Resources Information Center

    Matricano, Diego

    2010-01-01

    In markets characterized by strong competition, new knowledge and new knowledge development are generally recognized as the key means for an enterprise to gain competitive advantage. This knowledge-based competitive advantage is critical for all commercial ventures, but is especially so for high-expectation start-ups (technology-based ventures…

  7. High-gain and low-excess noise near-infrared single-photon avalanche detector arrays

    NASA Astrophysics Data System (ADS)

    Linga, Krishna; Yevtukhov, Yuriy; Liang, Bing

    2010-04-01

    We have designed and developed a new family of photodetectors and arrays with Internal Discrete Amplification (IDA) mechanism for the realization of very high gain and low excess noise factor in the visible and near infrared spectral regions. These devices surpass many limitations of the Single Photon Avalanche Photodetectors such as ultra low excess noise factor, very high gain, lower reset time (< 200 ns). These devices are very simple to operate in the non-gated mode under a constant dc bias voltage. Because of its unique characteristics of self-quenching and self-recovery, no external quenching circuit is needed. This unique feature of self quenching and self-recovery makes it simple to less complex readout integrated circuit to realize large format detector arrays. In this paper, we present the discrete amplification design approach used for the development of self reset, high gain photodetector arrays in the near infrared wavelength region. The demonstrated device performance far exceeds any available solid state Photodetectors in the near infrared wavelength range. These devices are ideal for researchers in the field of spectroscopy, industrial and scientific instrumentation, Ladar, quantum cryptography, night vision and other military, defense and aerospace applications.

  8. Transgenic Rescue of Adipocyte Glucose-dependent Insulinotropic Polypeptide Receptor Expression Restores High Fat Diet-induced Body Weight Gain*

    PubMed Central

    Ugleholdt, Randi; Pedersen, Jens; Bassi, Maria Rosaria; Füchtbauer, Ernst-Martin; Jørgensen, Signe Marie; Kissow, Hanne-Louise; Nytofte, Nikolaj; Poulsen, Steen Seier; Rosenkilde, Mette Marie; Seino, Yutaka; Thams, Peter; Holst, Peter Johannes; Holst, Jens Juul

    2011-01-01

    The glucose-dependent insulinotropic polypeptide receptor (GIPr) has been implicated in high fat diet-induced obesity and is proposed as an anti-obesity target despite an uncertainty regarding the mechanism of action. To independently investigate the contribution of the insulinotropic effects and the direct effects on adipose tissue, we generated transgenic mice with targeted expression of the human GIPr to white adipose tissue or beta-cells, respectively. These mice were then cross-bred with the GIPr knock-out strain. The central findings of the study are that mice with GIPr expression targeted to adipose tissue have a similar high fat diet -induced body weight gain as control mice, significantly greater than the weight gain in mice with a general ablation of the receptor. Surprisingly, this difference was due to an increase in total lean body mass rather than a gain in total fat mass that was similar between the groups. In contrast, glucose-dependent insulinotropic polypeptide-mediated insulin secretion does not seem to be important for regulation of body weight after high fat feeding. The study supports a role of the adipocyte GIPr in nutrient-dependent regulation of body weight and lean mass, but it does not support a direct and independent role for the adipocyte or beta-cell GIPr in promoting adipogenesis. PMID:22027838

  9. Achieving high performance polymer optoelectronic devices for high efficiency, long lifetime and low fabrication cost

    NASA Astrophysics Data System (ADS)

    Huang, Jinsong

    60 based device accidentally. The high PM factor makes it good candidate for photo detector. The high gain was assigned to the trapped-charge induced enhanced-injection at C60/PEDOT:PSS interface.

  10. Overexpression of Jazf1 reduces body weight gain and regulates lipid metabolism in high fat diet

    SciTech Connect

    Jang, Woo Young; Bae, Ki Beom; Kim, Sung Hyun; Yu, Dong Hun; Kim, Hei Jung; Ji, Young Rae; Park, Seo Jin; Park, Si Jun; Kang, Min-Cheol; Jeong, Ja In; Park, Sang-Joon; Lee, Sang Gyu; Lee, Inkyu; Kim, Myoung Ok; Yoon, Duhak; Ryoo, Zae Young

    2014-02-14

    Highlights: • The expression of Jazf1 in the liver suppressed lipid accumulation. • Jazf1 significantly increases transcription of fatty acid synthase. • Jazf1 plays a critical role in the regulation of energy and lipid homeostasis. • Jazf1 associates the development of metabolic disorder. • Jazf1 may provide a new therapeutic target in the management of metabolic disorder. - Abstract: Jazf1 is a 27 kDa nuclear protein containing three putative zinc finger motifs that is associated with diabetes mellitus and prostate cancer; however, little is known about the role that this gene plays in regulation of metabolism. Recent evidence indicates that Jazf1 transcription factors bind to the nuclear orphan receptor TR4. This receptor regulates PEPCK, the key enzyme involved in gluconeogenesis. To elucidate Jazf1’s role in metabolism, we fed a 60% fat diet for up to 15 weeks. In Jazf1 overexpression mice, weight gain was found to be significantly decreased. The expression of Jazf1 in the liver also suppressed lipid accumulation and decreased droplet size. These results suggest that Jazf1 plays a critical role in the regulation of lipid homeostasis. Finally, Jazf1 may provide a new therapeutic target in the management of obesity and diabetes.

  11. Very High Energy Gain at the Neptune Inverse Free Electron Laser Experiment

    SciTech Connect

    Musumeci, P.; Boucher, S.; Doyuran, A.; England, R. J.; Pellegrini, C.; Rosenzweig, J. B.; Travish, G.; Yoder, R.; Tochitsky, S.Ya.; Joshi, C.; Ralph, J.; Sung, C.; Tolmachev, S.; Varfolomeev, A.; Varfolomeev, A. Jr.; Yarovoi, T.

    2004-12-07

    We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 {mu}m laser with power larger than 400 GW. The Rayleigh range of the laser, {approx} 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Three-dimensional simulations, in good agreement with the measured electron energy spectrum, indicate that most of the acceleration occurs in the first 25 cm of the undulator, corresponding to an energy gradient larger than 70 MeV/m. The measured energy spectrum also indicates that higher harmonic Inverse Free Electron Laser interaction takes place in the second section of the undulator.

  12. The impact of collective teacher efficacy on student achievement in high school science

    NASA Astrophysics Data System (ADS)

    Burcham, Mark W.

    This dissertation was designed to examine the impact of collective teacher efficacy on high school science achievement by looking at relationships among collective teacher efficacy, its two constructs, group competence and group task analysis, and high school science achievement scores at four rural high schools in Northwestern North Carolina. The researcher gathered historical test data from the testing coordinator from the school system and then administered the Collective Teacher Efficacy Instrument, developed by Goddard, Hoy, and Woolfolk Hoy (2000), to 24 science teachers from the four high schools. Using this information, the researcher conducted statistical analyses to determine the relationships among collective teacher efficacy, group competence, and group task analysis as compared with the tested science curriculum (physical science, biology, chemistry, and physics). The researcher also examined which construct was the most contributing factor and examined differences in efficacy levels and student achievement levels at each high school. Analysis of the data from this study indicated collective teacher efficacy, as well as its two constructs, group competence and group task analysis, does have a positive impact on student achievement in high school science. Analysis of the data revealed group competence is the major contributing factor for student achievement in biology and group task analysis is the major contributing factor for student achievement in physical science, chemistry, and physics. Further analysis of the data in this study, also revealed that the two high schools with the highest levels of collective teacher efficacy had the highest levels of student achievement.

  13. Eigenmode analysis of a high-gain free-electron laser based on a transverse gradient undulator

    NASA Astrophysics Data System (ADS)

    Baxevanis, Panagiotis; Huang, Zhirong; Ruth, Ronald; Schroeder, Carl B.

    2015-01-01

    The use of a transverse gradient undulator (TGU) is viewed as an attractive option for free-electron lasers (FELs) driven by beams with a large energy spread. By suitably dispersing the electron beam and tilting the undulator poles, the energy spread effect can be substantially mitigated. However, adding the dispersion typically leads to electron beams with large aspect ratios. As a result, the presence of higher-order modes in the FEL radiation can become significant. To investigate this effect, we study the eigenmode properties of a TGU-based, high-gain FEL, using both an analytically-solvable model and a variational technique. Our analysis, which includes the fundamental and the higher-order FEL eigenmodes, can provide an estimate of the mode content for the output radiation. This formalism also enables us to study the trade-off between FEL gain and transverse coherence. Numerical results are presented for a representative soft X-ray, TGU FEL example.

  14. Semiconductor nanoplatelets: a new colloidal system for low-threshold high-gain stimulated emission (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Pelton, Matthew A.; She, Chunxing; Fedin, Igor; Dolzhnikov, Dmitriy; Ithurria, Sandrine; Baghani, Erfan; O'Leary, Stephen K.; Demortiere, Arnaud; Schaller, Richard D.; Talapin, Dmitri V.

    2015-10-01

    Quantum wells (QWs) are thin semiconductor layers than confine electrons and holes in one dimension. They are widely used for optoelectronic devices, particularly semiconductor lasers, but have so far been produced using expensive epitaxial crystal-growth techniques. This has motivated research into the use of colloidal semiconductor nanocrystals, which can be synthesized chemically at low cost, and can be processed in the solution phase. However, initial demonstrations of optical gain from colloidal nanocrystals involved high thresholds. Recently, colloidal synthesis methods have been developed for the production of thin, atomically flat semiconductor nanocrystals, known as nanoplatelets (NPLs). We investigated relaxation of high-energy carriers in colloidal CdSe NPLs, and found that the relaxation is characteristic of a QW system. Carrier cooling and relaxation on time scales from picoseconds to hundreds of picoseconds are dominated by Auger-type exciton-exciton interactions. The picosecond-scale cooling of hot carriers is much faster than the exciton recombination rate, as required for use of these NPLs as optical gain and lasing materials. We therefore investigated amplified spontaneous emission using close-packed films of NPLs. We observed thresholds that were more than 4 times lower than the best reported value for colloidal nanocrystals. Moreover, gain in these films is 4 times higher than gain reported for other colloidal nanocrystals, and saturates at pump fluences more than two orders of magnitude above the ASE threshold. We attribute this exceptional performance to large optical cross-sections, relatively slow Auger recombination rates, and narrow ensemble emission linewidths.

  15. Latino Access to Preschool Stalls after Earlier Gains: Certain to Harden Achievement Gaps, Erode Workforce Quality. New Journalism on Latino Children

    ERIC Educational Resources Information Center

    Fuller, Bruce; Kim, Anthony Y.

    2011-01-01

    It has been known that quality preschool can boost children's early literacy and social agility, skills valued highly by employers. The returns to preschool appear to be stronger for Latino children, especially those from non-English speaking families, compared with other populations. But newly available data reveal that preschool enrollment…

  16. An Investigation of Student Characteristics as Related to Achievement in an Individualized High School Biology Program.

    ERIC Educational Resources Information Center

    Littlefield, David L.

    Reported is a study of possible differences in student characteristics between high, expected, and low achievers in an individualized learning biology program. Nine variables, ranging from biographical data through attitudinal data were studied. Effects on achievement and explanation of some of the differences were determined by examination of…

  17. The Effects of Cooperative Learning on Student Achievement and Motivation in a High School Geometry Class.

    ERIC Educational Resources Information Center

    Nichols, Joe D.; Hall, Neff

    In this study, the effects of a form of cooperative group instruction (Student Teams Achievement Divisions) on student motivation and achievement in a high school geometry class were examined. Ninety (mostly 10th-grade) students were randomly assigned to either a control group receiving traditional instruction or one of two treatment groups…

  18. A Quantitative Comparison of Pennsylvania High School Student Achievement by Middle States Association's Accreditation Status

    ERIC Educational Resources Information Center

    Johnson, Christopher A.

    2012-01-01

    As public school accountability for student achievement has continued to increase, prior to and as a result of the No Child Left Behind Act of 2001, schools have sought ways of bringing new instructional services to their students to raise their levels of achievement. Some Pennsylvania public high schools have attempted to improve student…

  19. Unforgiving Confucian Culture: A Breeding Ground for High Academic Achievement, Test Anxiety and Self-Doubt?

    ERIC Educational Resources Information Center

    Stankov, Lazar

    2010-01-01

    This paper reviews findings from several studies that contribute to our understanding of cross-cultural differences in academic achievement, anxiety and self-doubt. The focus is on comparisons between Confucian Asian and European regions. Recent studies indicate that high academic achievement of students from Confucian Asian countries is…

  20. An Analysis of Mathematics Course Sequences for Low Achieving Students at a Comprehensive Technical High School

    ERIC Educational Resources Information Center

    Edge, D. Michael

    2011-01-01

    This non-experimental study attempted to determine how the different prescribed mathematic tracks offered at a comprehensive technical high school influenced the mathematics performance of low-achieving students on standardized assessments of mathematics achievement. The goal was to provide an analysis of any statistically significant differences…

  1. Instructional, Transformational, and Managerial Leadership and Student Achievement: High School Principals Make a Difference

    ERIC Educational Resources Information Center

    Valentine, Jerry W.; Prater, Mike

    2011-01-01

    This statewide study examined the relationships between principal managerial, instructional, and transformational leadership and student achievement in public high schools. Differences in student achievement were found when schools were grouped according to principal leadership factors. Principal leadership behaviors promoting instructional and…

  2. Scholastic Achievement in High School Explained? Validation of a Longitudinal Structural Equations Model

    ERIC Educational Resources Information Center

    Hellle, Laura; Tuijula, Tiina; Laakkonen, Eero

    2009-01-01

    The purpose of the study is to shed light on the mechanisms behind scholastic achievement in high school by testing a structural equations model based on the work by Vermunt (1998). It was presumed that self-regulation of learning would predict scholastic achievement and that learning orientations would predict self-regulation of learning. A…

  3. Predicting Early Academic Failure in High School from Prior Academic Achievement, Psychosocial Characteristics, and Behavior

    ERIC Educational Resources Information Center

    Casillas, Alex; Robbins, Steve; Allen, Jeff; Kuo, Yi-Lung; Hanson, Mary Ann; Schmeiser, Cynthia

    2012-01-01

    The authors examined the differential effects of prior academic achievement, psychosocial, behavioral, demographic, and school context factors on early high school grade point average (GPA) using a prospective study of 4,660 middle-school students from 24 schools. The findings suggest that (a) prior grades and standardized achievement are the…

  4. Accelerated Mathematics and High-Ability Students' Math Achievement in Grades Three and Four

    ERIC Educational Resources Information Center

    Stanley, Ashley M.

    2011-01-01

    The purpose of this study was to explore the relationship between the use of a computer-managed integrated learning system entitled Accelerated Math (AM) as a supplement to traditional mathematics instruction on achievement as measured by TerraNova achievement tests of third and fourth grade high-ability students. Gender, socioeconomic status, and…

  5. Early Reading Skills and Academic Achievement Trajectories of Students Facing Poverty, Homelessness, and High Residential Mobility

    ERIC Educational Resources Information Center

    Herbers, Janette E.; Cutuli, J. J.; Supkoff, Laura M.; Heistad, David; Chan, Chi-Keung; Hinz, Elizabeth; Masten, Ann S.

    2012-01-01

    This investigation tested the importance of early academic achievement for later achievement trajectories among 18,011 students grouped by level of socioeconomic risk. Students considered to be at highest risk were those who experienced homelessness or high residential mobility (HHM). HHM students were compared with students eligible for free…

  6. Gender and High School Chemistry: Student Perceptions on Achievement in a Selective Setting

    ERIC Educational Resources Information Center

    Cousins, Andrew; Mills, Martin

    2015-01-01

    This paper reports on research undertaken in a middle-class Australian school. The focus of the research was on the relationship between gender and students' engagement with high school chemistry. Achievement data from many OECD [Organisation for Economic Co-operation and Development] countries suggest that middle-class girls are achieving equally…

  7. Cohort versus Non-Cohort High School Students' Math Performance: Achievement Test Scores and Coursework

    ERIC Educational Resources Information Center

    Parke, Carol S.; Keener, Dana

    2011-01-01

    The purpose of this study is to compare multiple measures of mathematics achievement for 1,378 cohort students who attended the same high school in a district from 9th to 12th grade with non-cohort students in each grade level. Results show that mobility had an impact on math achievement. After accounting for gender, ethnicity, and SES, adjusted…

  8. The Impact of Charter Schools on Promoting High Levels of Mathematics Achievement

    ERIC Educational Resources Information Center

    Plucker, Jonathan A.; Makel, Matthew C.; Rapp, Kelly E.

    2007-01-01

    This study compares achievement levels for high ability students attending charter schools and students in traditional public schools in Georgia. Researchers examined student achievement (as assessed by the state's Criterion-Referenced Competency Tests) using three comparison groups: students in the closest traditional schools with similar grade…

  9. The Impact of Placement on Reading and Mathematics Achievement of Students with High Incidence Disabilities

    ERIC Educational Resources Information Center

    Harrington, Jennifer Stell

    2011-01-01

    The question of where best to educate students with disabilities to maximize their academic achievement has been discussed and researched for over four decades, with inconsistent and contradictory results. This study focused on the mathematics and reading achievement of middle and high school students with mild disabilities in an urban district in…

  10. Parental Involvement, Homework, and TV Time: Direct and Indirect Effects on High School Achievement.

    ERIC Educational Resources Information Center

    Keith, Timothy Z.; And Others

    1986-01-01

    A set of High School and Beyond data was used to study the effect of three variables on academic achievement. Homework had a positive effect, TV a negative, and parental involvement no direct effect on seniors' achievement scores, but influenced the amount of time students spent on homework. (Author/JAZ)

  11. Low and High Mathematics Achievement in Japanese, Chinese, and American Elementary-School Children.

    ERIC Educational Resources Information Center

    Uttal, David H.; And Others

    1988-01-01

    First and fifth grade students who scored high or low on a mathematics test were tested for intellectual ability and reading achievement. Students and their mothers were interviewed. Results indicated that factors associated with levels of achievement in mathematics operate in a similar fashion across three cultures that differ greatly in their…

  12. High-power 1.25 µm InAs QD VECSEL based on resonant periodic gain structure

    NASA Astrophysics Data System (ADS)

    Albrecht, Alexander R.; Rotter, Thomas J.; Hains, Christopher P.; Stintz, Andreas; Xin, Guofeng; Wang, Tsuei-Lian; Kaneda, Yushi; Moloney, Jerome V.; Malloy, Kevin J.; Balakrishnan, Ganesh

    2011-03-01

    We compare an InAs quantum dot (QD) vertical external-cavity surface-emitting laser (VECSEL) design consisting of 4 groups of 3 closely spaced QD layers with a resonant periodic gain (RPG) structure, where each of the 12 QD layers is placed at a separate field antinode. This increased the spacing between the QDs, reducing strain and greatly improving device performance. For thermal management, the GaAs substrate was thinned and indium bonded to CVD diamond. A fiber-coupled 808 nm diode laser was used as pump source, a 1% transmission output coupler completed the cavity. CW output powers over 4.5 W at 1250 nm were achieved.

  13. Multifunctional Polymer Nanofibers: UV Emission, Optical Gain, Anisotropic Wetting, and High Hydrophobicity for Next Flexible Excitation Sources

    PubMed Central

    2015-01-01

    The use of UV light sources is highly relevant in many fields of science, being directly related to all those detection and diagnosis procedures that are based on fluorescence spectroscopy. Depending on the specific application, UV light-emitting materials are desired to feature a number of opto-mechanical properties, including brightness, optical gain for being used in laser devices, flexibility to conform with different lab-on-chip architectures, and tailorable wettability to control and minimize their interaction with ambient humidity and fluids. In this work, we introduce multifunctional, UV-emitting electrospun fibers with both optical gain and greatly enhanced anisotropic hydrophobicity compared to films. Fibers are described by the onset of a composite wetting state, and their arrangement in uniaxial arrays further favors liquid directional control. The low gain threshold, optical losses, plastic nature, flexibility, and stability of these UV-emitting fibers make them interesting for building light-emitting devices and microlasers. Furthermore, the anisotropic hydrophobicity found is strongly synergic with optical properties, reducing interfacial interactions with liquids and enabling smart functional surfaces for droplet microfluidic and wearable applications. PMID:26401889

  14. Multifunctional Polymer Nanofibers: UV Emission, Optical Gain, Anisotropic Wetting, and High Hydrophobicity for Next Flexible Excitation Sources.

    PubMed

    Morello, Giovanni; Manco, Rita; Moffa, Maria; Persano, Luana; Camposeo, Andrea; Pisignano, Dario

    2015-10-01

    The use of UV light sources is highly relevant in many fields of science, being directly related to all those detection and diagnosis procedures that are based on fluorescence spectroscopy. Depending on the specific application, UV light-emitting materials are desired to feature a number of opto-mechanical properties, including brightness, optical gain for being used in laser devices, flexibility to conform with different lab-on-chip architectures, and tailorable wettability to control and minimize their interaction with ambient humidity and fluids. In this work, we introduce multifunctional, UV-emitting electrospun fibers with both optical gain and greatly enhanced anisotropic hydrophobicity compared to films. Fibers are described by the onset of a composite wetting state, and their arrangement in uniaxial arrays further favors liquid directional control. The low gain threshold, optical losses, plastic nature, flexibility, and stability of these UV-emitting fibers make them interesting for building light-emitting devices and microlasers. Furthermore, the anisotropic hydrophobicity found is strongly synergic with optical properties, reducing interfacial interactions with liquids and enabling smart functional surfaces for droplet microfluidic and wearable applications. PMID:26401889

  15. Manifest Needs of High Ability Achieving and Underachieving Elementary School Children in a Culturally Disadvantaged Setting

    ERIC Educational Resources Information Center

    Masih, Lalit K.

    1974-01-01

    This study, conducted in conjunction with a larger project entitled "Project Able" (part of the Madison Area Project), compared manifest needs of high ability achieving and underachieving elementary school children in a culturally disadvantaged setting. (EAK)

  16. Understanding the Elements of Operational Reliability: A Key for Achieving High Reliability

    NASA Technical Reports Server (NTRS)

    Safie, Fayssal M.

    2010-01-01

    This viewgraph presentation reviews operational reliability and its role in achieving high reliability through design and process reliability. The topics include: 1) Reliability Engineering Major Areas and interfaces; 2) Design Reliability; 3) Process Reliability; and 4) Reliability Applications.

  17. Toward the realization of erbium-doped GaN bulk crystals as a gain medium for high energy lasers

    NASA Astrophysics Data System (ADS)

    Sun, Z. Y.; Li, J.; Zhao, W. P.; Lin, J. Y.; Jiang, H. X.

    2016-08-01

    Er-doped GaN (Er:GaN) is a promising candidate as a gain medium for solid-state high energy lasers (HELs) at the technologically important and eye-safe 1.54 μm wavelength window, as GaN has superior thermal properties over traditional laser gain materials such as Nd:YAG. However, the attainment of wafer-scale Er:GaN bulk or quasi-bulk crystals is a prerequisite to realize the full potential of Er:GaN as a gain medium for HELs. We report the realization of freestanding Er:GaN wafers of 2-in. in diameter with a thickness on the millimeter scale. These freestanding wafers were obtained via growth by hydride vapor phase epitaxy in conjunction with a laser-lift-off process. An Er doping level of 1.4 × 1020 atoms/cm3 has been confirmed by secondary ion mass spectrometry measurements. The freestanding Er:GaN wafers exhibit strong photoluminescent emission at 1.54 μm with its emission intensity increasing dramatically with wafer thickness under 980 nm resonant excitation. A low thermal quenching of 10% was measured for the 1.54 μm emission intensity between 10 K and 300 K. This work represents a significant step in providing a practical approach for producing Er:GaN materials with sufficient thicknesses and dimensions to enable the design of gain media in various geometries, allowing for the production of HELs with improved lasing efficiency, atmosphere transmission, and eye-safety.

  18. An experimental analysis of the waveguide modes in a high-gain free-electron laser amplifier

    SciTech Connect

    Anderson, B.R.

    1989-01-01

    The presence, growth, and interaction of transverse waveguide modes in high-gain free-electron laser (FEL) amplifiers has been observed and studied. Using the Electron Laser Facility at Lawrence Livermore National Laboratory, a 3 MeV, 800 A electron beam generated by the Experimental Test Accelerator was injected into a planar wiggler. Power was then extracted and measured in the fundamental (TE{sub 01}) an higher-order modes (Te{sub 21} and TM{sub 21}) under various sets of operating conditions. Horizontal focusing through the wiggler was provided by external quadrupole magnets. There was no axial guide field. The input microwave signal for amplification was generated by a 100 kW magnetron operating at 34.6 Ghz. Power measurements were taken for both flat and tapered wigglers, for two sizes of waveguide, and for both flat and tapered wigglers, for two sizes of waveguide, and for both fundamental and higher mode injection. Mode content was determined by sampling the radiated signal at specific points in the radiation patter. For the flat wiggler and with the large waveguide (2.9 cm {times} 9.8 cm) the power in the higher modes was comparable to power in the fundamental. both exhibited gains greater than 30 dB/m prior to saturation and both reached powers in excess of 80 MW. Choice of injection mode had little effect on the operation of the system. Operation with the smaller guide (WR-229) provided much better mode selectivity. The fundamental mode continued to show optimum gain in excess of 30 dB/m while the higher-mode gain was of order 20 dB/m. As expected, power output increased significantly with the tapered wigglers. The relative mode content depended on the specific taper used.

  19. Shuttle orbiter Ku-band radar/communications system design evaluation: High gain antenna/widebeam horn

    NASA Technical Reports Server (NTRS)

    Iwasaki, R.; Dodds, J. G.; Broad, P.

    1979-01-01

    The physical characteristics of the high gain antenna reflector and feed elements are described. Deficiencies in the sum feed are discussed, and lack of atmospheric venting is posed as a potential problem area. The measured RF performance of the high gain antenna is examined and the high sidelobe levels measured are related to the physical characteristics of the antenna. An examination of the attributes of the feed which might be influenced by temperature extremes shows that the antenna should be insensitive to temperature variations. Because the feed support bipod structure is considered a significant contributor to the high sidelobe levels measured in the azimuth plane, pod relocation, material changes, and shaping are suggested as improvements. Alternate feed designs are presented to further improve system performance. The widebeam horn and potential temperature effects due to the polarizer are discussed as well as in the effects of linear polarization on TDRS acquisition, and the effects of circular polarization on radar sidelobe avoidance. The radar detection probability is analyzed as a function of scan overlap and target range.

  20. What Do High School Science Students Gain from Field-Based Research Apprenticeship Programs?

    ERIC Educational Resources Information Center

    Abraham, Linda M.

    2002-01-01

    Addresses how to encourage and sustain high school students' interest in science. Evaluates the Earthwatch Institute's Student Challenge Awards Program, an apprenticeship program which allows students to work on authentic research projects. Concludes the program had a profound impact on the students' understanding of and affinity for science. (PM)

  1. Energy gain and spectral tailoring of ion beams using ultra-high intensity laser beams

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra; Swantusch, Marco; Cerchez, Mirela; Spickermann, Sven; Auorand, Bastian; Wowra, Thomas; Boeker, Juergen; Willi, Oswald

    2015-11-01

    The field of laser driven ion acceleration over the past decade has produced a huge amount of research. Nowadays, several multi-beam facilities with high rep rate system, e.g. ELI, are being developed across the world for different kinds of experiments. The study of interaction dynamics of multiple beams possessing ultra-high intensity and ultra-short pulse duration is of vital importance. Here, we present the first experimental results on ion acceleration using two ultra-high intensity beams. Thanks to the unique capability of Arcturus laser at HHU Düsseldorf, two almost identical, independent beams in laser parameters such as intensity (>1020 W/cm2), pulse duration (30 fs) and contrast (>1010), could be accessed. Both beams are focused onto a 5 μm thin Ti target. While ensuring spatial overlap of the two beams, at relative temporal delay of ~ 50 ps (optimum delay), the proton and carbon ion energies were enhanced by factor of 1.5. Moreover, strong modulation in C4+ions near the high energy cut-off is observed later than the optimum delay for the proton enhancement. This offers controlled tailoring of the spectral content of heavy ions.

  2. A critical examination of the evidence relating high fructose corn syrup and weight gain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of high fructose corn syrup (HFCS) has increased over the past several decades in the United States while overweight and obesity rates have risen dramatically. Some scientists hypothesize that HFCS consumption has uniquely contributed to the increasing mean body mass index (BMI) of the U.S....

  3. Highly Sensitive, Encapsulated MoS2 Photodetector with Gate Controllable Gain and Speed.

    PubMed

    Kufer, Dominik; Konstantatos, Gerasimos

    2015-11-11

    Semiconducting, two-dimensional molybdenum disulfide (MoS2) is considered a promising new material for highly sensitive photodetection, because of its atomically thin profile and favorable bandgap. However, reported photodetectors to date show strong variation in performance due to the detrimental and uncontrollable effects of environmental adsorbates on devices due to large surface to volume ratio. Here, we report on highly stable and high-performance monolayer and bilayer MoS2 photodetectors encapsulated with atomic layer deposited hafnium oxide. The protected devices show enhanced electronic properties by isolating them from the ambience as strong n-type doping, vanishing hysteresis, and reduced device resistance. By controlling the gate voltage the responsivity and temporal response can be tuned by several orders of magnitude with R ∼ 10-10(4) A/W and t ∼ 10 ms to 10 s. At strong negative gate voltage, the detector is operated at higher speed and simultaneously exhibits a low-bound, record sensitivity of D* ≥ 7.7 × 10(11) Jones. Our results lead the way for future application of ultrathin, flexible, and high-performance MoS2 detectors and prompt for further investigation in encapsulated transition metal dichalcogenide optoelectronics. PMID:26501356

  4. Simulations of high-gain shock-ignited inertial-confinement-fusion implosions using less than 1 MJ of direct KrF-laser energy

    NASA Astrophysics Data System (ADS)

    Bates, Jason W.; Schmitt, Andrew J.; Fyfe, David E.; Obenschain, Steve P.; Zalesak, Steve T.

    2010-06-01

    In this paper, we report on recent numerical simulations of inertial-confinement-fusion (ICF) implosions using the FAST radiation hydrocode at the U.S. Naval Research Laboratory. Our study focuses on three classes of shock-ignited target designs utilizing less than 1 MJ of direct, krypton-fluoride (KrF) laser energy, which was "zoomed" to maximize the coupling efficiency. In the shock-ignition approach [R. Betti, C.D. Zhou, K.S. Anderson, et al., Phys. Rev. Lett. 98 (2007) 155001], a moderate-intensity, compressive laser pulse is followed by a short-duration high-intensity spike that launches a spherically-convergent shock wave to ignite a thick shell of compressed fuel. Such an arrangement appears to offer several significant advantages, including a low ignition threshold, high gain, and less susceptibility to the deleterious effects of hydrodynamic and laser-plasma instabilities. According to one-dimensional simulations, fusion gains over 200 can be achieved with shock-ignited targets using less than 750 kJ of laser energy. This represents a significant improvement in performance over conventional centrally-ignited designs. To examine the stability of these targets, several two-dimensional simulations were also performed that incorporated realistic perturbation sources such as laser imprinting and roughness spectra for inner/outer pellet surfaces. Although the simulations indicate that appreciable low-mode distortion of the fuel shell can occur at late time as a result of these perturbations, high gains are still achieved in many cases owing to the low in-flight aspect ratios of shock-ignited targets. We should remark, though, that the high convergence ratios of these same designs suggest that other sources of low-mode asymmetries, which were not considered in this study (e.g., beam misalignment and energy-balance errors), may be important in determining overall pellet stability and performance. We discuss these issues, as well as other salient design

  5. Bullying and Victimization Rates among Gifted and High-Achieving Students

    ERIC Educational Resources Information Center

    Peters, Megan Parker; Bain, Sherry K.

    2011-01-01

    Bullying and victimization rates among 90 gifted and nongifted, high-achieving (HA) high school students were assessed by using the Reynolds Bully Victimization Scale (BVS; W. M. Reynolds, 2003). The mean scores indicate that gifted and HA high school students bully others and are victimized by others generally at unelevated rates based on BVS…

  6. A Study of Professional Learning Communities and Science Achievement in Large High Schools

    ERIC Educational Resources Information Center

    Kincannon, Susan D.

    2010-01-01

    The purpose of this study was to compare the science achievement and high school completion rates of students in a large high school implementing professional learning community concepts and practices with two large high schools not participating in professional learning community concepts and practices. The primary methodology employed was a…

  7. Do Peers Influence Achievement in High School Economics? Evidence from Georgia's Economics End of Course Test

    ERIC Educational Resources Information Center

    Clark, Christopher; Scafidi, Benjamin; Swinton, John R.

    2011-01-01

    The authors provide the first estimates of the impact of peers on achievement in high school economics. The estimates are obtained by analyzing three years of data on all high school students who take Georgia's required economics course and its accompanying high-stakes End of Course Test (Georgia Department of Education). They use an instrumental…

  8. High peak- and average-power pulse shaped fiber laser in the ns-regime applying step-index XLMA gain fibers

    NASA Astrophysics Data System (ADS)

    Dinger, R.; Grundmann, F.-P.; Hapke, C.; Ruppik, S.

    2014-03-01

    Pulsed fiber lasers and continuous-wave (cw) fiber lasers have become the tool of choice in more and more laser based industrial applications like metal cutting and welding mainly because of their robustness, compactness, high brightness, high efficiency and reasonable costs. However, to further increase the productivity with those laser types there is a great demand for even higher laser power specifications. In this context we demonstrate a pulsed high peak- and averagepower fiber laser in a Master Oscillator Power Amplifier (MOPA) configuration with selectable pulse durations between 1 ns and several hundred nanoseconds. To overcome fiber nonlinearities such as stimulated Raman scattering (SRS) and self-phase-modulation (SPM) flexible Ytterbium doped extra-large mode area (XLMA) step index fibers, prepared by novel powder-sinter technology, have been used as gain fibers. As an example, for 12 ns pulses with a repetition rate of 10 kHz, a pump power limited average laser output power of more than 400 W in combination with peak powers of more than 3.5 MW (close to self-focusing-threshold) has been achieved in stable operation. The potentials of this laser system have been further explored towards longer pulse durations in order to achieve even higher pulse energies by means of pulse shaping techniques. In addition, investigations have been conducted with reduced pulse energies and repetition rates up to 500 kHz and average powers of more than 500 W at nearly diffraction limited beam quality.

  9. Petawatt laser pulses for proton-boron high gain fusion with avalanche reactions excluding problems of nuclear radiation

    NASA Astrophysics Data System (ADS)

    Hora, Heinrich; Lalousis, Paraskevas; Giuffrida, Lorenzo; Margarone, Daniele; Korn, Georg; Eliezer, Shalom; Miley, George H.; Moustaizis, Stavros; Mourou, Gérard

    2015-05-01

    An alternative way may be possible for igniting solid density hydrogen-11B (HB11) fuel. The use of >petawatt-ps laser pulses from the non-thermal ignition based on ultrahigh acceleration of plasma blocks by the nonlinear (ponderomotive) force, has to be combined with the measured ultrahigh magnetic fields in the 10 kilotesla range for cylindrical trapping. The evaluation of measured alpha particles from HB11 reactions arrives at the conclusion that apart from the usual binary nuclear reactions, secondary reactions by an avalanche multiplication may cause the high gains, even much higher than from deuterium tritium fusion. This may be leading to a concept of clean economic power generation.

  10. Statistical properties of radiation power levels from a high-gain free-electron laser at and beyond saturation

    SciTech Connect

    Schroeder, Carl B.; Fawley, William M.; Esarey, Eric

    2002-09-24

    We investigate the statistical properties (e.g., shot-to-shot power fluctuations) of the radiation from a high-gain free-electron laser (FEL) operating in the nonlinear regime. We consider the case of an FEL amplifier reaching saturation whose shot-to-shot fluctuations in input radiation power follow a gamma distribution. We analyze the corresponding output power fluctuations at and beyond first saturation, including beam energy spread effects, and find that there are well-characterized values of undulator length for which the fluctuation level reaches a minimum.

  11. Transverse and temporal characteristics of a high-gain free-electron laser in the saturation regime

    NASA Astrophysics Data System (ADS)

    Huang, Zhirong; Kim, Kwang-Je

    2002-05-01

    The transverse and the temporal characteristics of a high-gain free-electron laser are governed by refractive guiding and sideband instability, respectively. Using the self-consistent Vlasov-Maxwell equations, we explicitly determine the effective index of refraction and the guided radiation mode for an electron beam with arbitrary transverse size. Electrons trapped by the guided radiation execute synchrotron oscillation and hence are susceptible to the sideband instability. We explain the spectral evolution and determine the sideband growth rate. These theoretical predictions agree well with GINGER simulation results.

  12. Characteristics of trap-filled gallium arsenide photoconductive switches used in high gain pulsed power applications

    SciTech Connect

    ISLAM,N.E.; SCHAMILOGLU,E.; MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; JOSHI,R.P.

    2000-05-30

    The electrical properties of semi-insulating (SI) Gallium Arsenide (GaAs) have been investigated for some time, particularly for its application as a substrate in microelectronics. Of late this material has found a variety of applications other than as an isolation region between devices, or the substrate of an active device. High resistivity SI GaAs is increasingly being used in charged particle detectors and photoconductive semiconductor switches (PCSS). PCSS made from these materials operating in both the linear and non-linear modes have applications such as firing sets, as drivers for lasers, and in high impedance, low current Q-switches or Pockels cells. In the non-linear mode, it has also been used in a system to generate Ultra-Wideband (UWB) High Power Microwaves (HPM). The choice of GaAs over silicon offers the advantage that its material properties allow for fast, repetitive switching action. Furthermore photoconductive switches have advantages over conventional switches such as improved jitter, better impedance matching, compact size, and in some cases, lower laser energy requirement for switching action. The rise time of the PCSS is an important parameter that affects the maximum energy transferred to the load and it depends, in addition to other parameters, on the bias or the average field across the switch. High field operation has been an important goal in PCSS research. Due to surface flashover or premature material breakdown at higher voltages, most PCSS, especially those used in high power operation, need to operate well below the inherent breakdown voltage of the material. The lifetime or the total number of switching operations before breakdown, is another important switch parameter that needs to be considered for operation at high bias conditions. A lifetime of {approximately} 10{sup 4} shots has been reported for PCSS's used in UWB-HPM generation [5], while it has exceeded 10{sup 8} shots for electro-optic drivers. Much effort is currently

  13. Origin of high photoconductive gain in fully transparent heterojunction nanocrystalline oxide image sensors and interconnects.

    PubMed

    Jeon, Sanghun; Song, Ihun; Lee, Sungsik; Ryu, Byungki; Ahn, Seung-Eon; Lee, Eunha; Kim, Young; Nathan, Arokia; Robertson, John; Chung, U-In

    2014-11-01

    A technique for invisible image capture using a photosensor array based on transparent conducting oxide semiconductor thin-film transistors and transparent interconnection technologies is presented. A transparent conducting layer is employed for the sensor electrodes as well as interconnection in the array, providing about 80% transmittance at visible-light wavelengths. The phototransistor is a Hf-In-Zn-O/In-Zn-O heterostructure yielding a high quantum-efficiency in the visible range. PMID:25219518

  14. Antagonism of T-type calcium channels inhibits high-fat diet–induced weight gain in mice

    PubMed Central

    Uebele, Victor N.; Gotter, Anthony L.; Nuss, Cindy E.; Kraus, Richard L.; Doran, Scott M.; Garson, Susan L.; Reiss, Duane R.; Li, Yuxing; Barrow, James C.; Reger, Thomas S.; Yang, Zhi-Qiang; Ballard, Jeanine E.; Tang, Cuyue; Metzger, Joseph M.; Wang, Sheng-Ping; Koblan, Kenneth S.; Renger, John J.

    2009-01-01

    The epidemics of obesity and metabolic disorders have well-recognized health and economic burdens. Pharmacologic treatments for these diseases remain unsatisfactory with respect to both efficacy and side-effect profiles. Here, we have identified a potential central role for T-type calcium channels in regulating body weight maintenance and sleep. Previously, it was shown that mice lacking CaV3.1 T-type calcium channels have altered sleep/wake activity. We found that these mice were also resistant to high-fat diet–induced weight gain, without changes in food intake or sensitivity to high-fat diet–induced disruptions of diurnal rhythm. Administration of a potent and selective antagonist of T-type calcium channels, TTA-A2, to normal-weight animals prior to the inactive phase acutely increased sleep, decreased body core temperature, and prevented high-fat diet–induced weight gain. Administration of TTA-A2 to obese rodents reduced body weight and fat mass while concurrently increasing lean muscle mass. These effects likely result from better alignment of diurnal feeding patterns with daily changes in circadian physiology and potentially an increased metabolic rate during the active phase. Together, these studies reveal what we believe to be a previously unknown role for T-type calcium channels in the regulation of sleep and weight maintenance and suggest the potential for a novel therapeutic approach to treating obesity. PMID:19451696

  15. High gain, low noise, fully complementary logic inverter based on bi-layer WSe2 field effect transistors

    NASA Astrophysics Data System (ADS)

    Das, Saptarshi; Dubey, Madan; Roelofs, Andreas

    2014-08-01

    In this article, first, we show that by contact work function engineering, electrostatic doping and proper scaling of both the oxide thickness and the flake thickness, high performance p- and n-type WSe2 field effect transistors (FETs) can be realized. We report record high drive current of 98 μA/μm for the electron conduction and 110 μA/μm for the hole conduction in Schottky barrier WSe2 FETs. Then, we combine high performance WSe2 PFET with WSe2 NFET in double gated transistor geometry to demonstrate a fully complementary logic inverter. We also show that by adjusting the threshold voltages for the NFET and the PFET, the gain and the noise margin of the inverter can be significantly enhanced. The maximum gain of our chemical doping free WSe2 inverter was found to be ˜25 and the noise margin was close to its ideal value of ˜2.5 V for a supply voltage of VDD = 5.0 V.

  16. High gain, low noise, fully complementary logic inverter based on bi-layer WSe{sub 2} field effect transistors

    SciTech Connect

    Das, Saptarshi; Roelofs, Andreas; Dubey, Madan

    2014-08-25

    In this article, first, we show that by contact work function engineering, electrostatic doping and proper scaling of both the oxide thickness and the flake thickness, high performance p- and n-type WSe{sub 2} field effect transistors (FETs) can be realized. We report record high drive current of 98 μA/μm for the electron conduction and 110 μA/μm for the hole conduction in Schottky barrier WSe{sub 2} FETs. Then, we combine high performance WSe{sub 2} PFET with WSe{sub 2} NFET in double gated transistor geometry to demonstrate a fully complementary logic inverter. We also show that by adjusting the threshold voltages for the NFET and the PFET, the gain and the noise margin of the inverter can be significantly enhanced. The maximum gain of our chemical doping free WSe{sub 2} inverter was found to be ∼25 and the noise margin was close to its ideal value of ∼2.5 V for a supply voltage of V{sub DD} = 5.0 V.

  17. Insights Gained from Modeling High-Grade Glioma in the Mouse

    PubMed Central

    Rankin, Sherri L.; Zhu, Guo; Baker, Suzanne J.

    2011-01-01

    High grade gliomas (HGG) are devastating primary brain tumors with universally poor prognoses. Advances toward effective treatments require improved understanding of pathogenesis and relevant model systems for preclinical testing. Mouse models for HGG provide physiologically relevant experimental systems for analysis of HGG pathogenesis. There are advantages and disadvantages to the different methodologies used to generate such models, including implantation, genetic engineering or somatic gene transfer approaches. This review highlights how mouse models have provided insights into the contribution of specific mutations to tumor initiation, progression, and phenotype, the influence of tumor microenviroment, and the analysis of cell types that can give rise to glioma. HGGs are a highly heterogeneous group of tumors, and the complexity of diverse mutations within common signaling pathways as well as the developmental and cell-type context of transformation contribute to the overall diversity of glioma phenotype. Enhanced understanding of the mutations and cell types giving rise to HGG, along with the ability to design increasingly complex mouse models that more closely approximate the process of human gliomagenesis will continue to provide improved experimental systems for dissecting mechanisms of disease pathogenesis and for preclinical testing. PMID:22035336

  18. Gain Evaluation of Micro-Channel-Plate Photomultipliers in the Upgraded High-B Test Facility at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Barber, Corinne; DIRC at EIC Collaboration

    2015-10-01

    The High-B test facility at Thomas Jefferson National Accelerator Facility allows researchers to evaluate the gain of compact photon sensors, such as Micro-Channel-Plate Photomultipliers (MCP-PMTs), in magnetic fields up to 5 T. These ongoing studies support the development of a Detector of Internally Reflected Cherenkov light (DIRC) to be used in an Electron Ion Collider (EIC). Here, we present our summer 2015 activities to upgrade and improve the facility, and we show results for MCP-PMT gain changes in high B-fields. To monitor the light stability delivered to the MCP-PMTs being tested, we implemented a Silicon Photomultiplier (SiPM) in the setup and calibrated the ADC reading this sensor. A 405-nm Light-Emitting Diode (LED) housed in an optical tube compatible with neutral density filters was also installed. The filters provide an alternative way of reducing the light output of the LED to operate the MCP-PMTs in a single-photon mode. We calibrated a set of filters by means of a photodiode and measured the photon flux at multiple positions relative to the LED. This information helped us to design 3D-printed holders unique to each MCP-PMT so that the photocathode receives the greatest amount of light. The improvements to the setup allow for more precise PMT gain evaluation. This team includes 7 collaborators/co-authors besides myself: Yordanka Ilieva, Kijun Park, Greg Kalicy, Carl Zorn, Pawel Nadel-Turonski, Tongtong Cao, and Lee.

  19. Erbium doping of lithium niobate by the ion exchange process for high-gain optical amplifiers

    NASA Astrophysics Data System (ADS)

    Caccavale, Frederico; Fedorov, Vyacheslav A.; Korkishko, Yuri N.; Morozova, Tamara V.; Sada, Cinzia; Segato, Francesco

    2000-04-01

    The erbium-lithium ion exchange is presented as a method for the erbium local doping of lithium niobate crystals. Ion exchange process is performed immersing the LiNbO3 substrates in a liquid melt, containing erbium ions; due to their high mobility, the lithium ions migrate from the crystal to the melt, and are replaced by erbium ions. A systematic analysis of the doping process is performed, and the influence of the process parameters is investigated: exchange time and temperature, crystal cut direction, composition and chemical reactivity of the Er ions liquid source. By structural (X-Ray Diffraction and Rutherford Backscattering Spectrometry), compositional (Secondary Ion Mass Spectrometry) and spectroscopic techniques (optical spectroscopy and micro-luminescence), the formation of lithium deficient phases and the incorporation of the Er ions into the LiNbO3 matrix is studied.

  20. A High-Gain Passive UHF-RFID Tag with Increased Read Range.

    PubMed

    Zuffanelli, Simone; Aguila, Pau; Zamora, Gerard; Paredes, Ferran; Martin, Ferran; Bonache, Jordi

    2016-01-01

    In this work, a passive ultra-high frequency radio-frequency identification UHF-RFID tag based on a 1.25 wavelengths thin dipole antenna is presented for the first time. The length of the antenna is properly chosen in order to maximize the tag read range, while maintaining a reasonable tag size and radiation pattern. The antenna is matched to the RFID chip by means of a very simple matching network based on a shunt inductance. A tag prototype, based on the Alien Higgs-3 chip, is designed and fabricated. The overall dimensions are 400 mm × 14.6 mm, but the tag width for most of its length is delimited by the wire diameter (0.8 mm). The measured read range exhibits a maximum value of 17.5 m at the 902-928 MHz frequency band. This represents an important improvement over state-of-the-art passive UHF-RFID tags. PMID:27455274