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Sample records for fels longitudinal study

  1. Validation of Maturity Offset in the Fels Longitudinal Study.

    PubMed

    Malina, Robert M; Choh, Audrey C; Czerwinski, Stefan A; Chumlea, Wm Cameron

    2016-08-01

    Sex-specific equations for predicting maturity offset, time before or after peak height velocity (PHV), were evaluated in 63 girls and 74 boys from the Fels Longitudinal Study. Serially measured heights (0.1 cm), sitting heights (0.1 cm), weights (0.1 kg), and estimated leg lengths (0.1 cm) from 8 to 18 years were used. Predicted age at PHV (years) was calculated as the difference between chronological age (CA) and maturity offset. Actual age at PHV for each child was derived with a triple logistic model (Bock-Thissen-du Toit). Mean predicted maturity offset was negative and lowest at 8 years and increased linearly with increasing CA. Predicted ages at PHV increased linearly with CA from 8 to 18 years in girls and from 8 to 13 years in boys; predictions varied within relatively narrow limits from 12 to 15 years and then increased to 18 years in boys. Differences between predicted and actual ages at PHV among youth of contrasting maturity status were significant across the age range in both sexes. Dependence of predicted age at PHV upon CA at prediction and on actual age at PHV limits its utility as an indicator of maturity timing and in sport talent programs. PMID:26757350

  2. Secular Trends in Body Composition for Children and Young Adults: The Fels Longitudinal Study

    PubMed Central

    Sun, Shumei S.; Deng, Xiaoyan; Sabo, Roy; Carrico, Robert; Schubert, Christine M.; Wan, Wen; Sabo, Cynthia

    2012-01-01

    Objectives To determine secular trends by birth decade in body mass index (BMI), waist circumference/height (W/Ht), percent body fat (PBF), and fat free mass adjusted for height squared (FFM/Ht2) in children and adolescents aged 8–18 years. Methods Serial data were analyzed from 628 boys and 591girls aged 8 to 18 years who participated in the Fels Longitudinal Study. Subjects were stratified by birth decade from 1960 through 1999. Means and standard deviations were computed for all measurements by birth decade, age and sex. A repeated-measures analysis of variance was used data to ascertain secular trends separately for boys and girls. Results Boys and girls born in the 1990s had significantly higher mean BMI, W/Ht and PBF than did children born in previous decades. Mean FFM/Ht2 was significantly smaller in boys born in the 1990s than boys of the same age born in earlier decades. No secular trend was noted in FFM/ Ht2 in girls by decade of birth. Conclusion Our analysis of serial data collected over four decades confirms the secular trend in childhood BMI previously observed in successive cross-sectional studies. Our analysis discloses significant positive secular trends in W/Ht and PBF in both boys and girls and a significant negative secular trend in FFM/Ht2 in boys over the last four decades of the 20th century. The secular changes presage increases in the prevalence of conditions associated with childhood and adolescent obesity – such as hypertension, glucose intolerance, and dyslipidemia – that may appear as early as the second decade of life. PMID:22410970

  3. Wrist Breadth and Homeostasis Model Assessment of Insulin Resistance in Youth: The Fels Longitudinal Study

    PubMed Central

    MUELLER, NOEL T.; JOHNSON, WILLIAM; ODEGAARD, ANDREW O.; LEE, MIRYOUNG; CZERWINSKI, STEFAN A.; DEMERATH, ELLEN W.

    2014-01-01

    Objectives There is biological crosstalk between insulin signaling and bone remodeling pathways, and wrist circumference and bone area were recently found to associate with insulin resistance independent of body mass index (BMI) in overweight/obese children. We aimed to expand on this work by using more specific measures of adiposity for adjustment and examining children with broader range of BMI. Methods We used serial data (1,051 total measures) on 313 non-Hispanic white youth (ages 8–18 y) from the Fels Longitudinal Study with homeostasis model assessment of insulin resistance (HOMA-IR) as the outcome. Internal standard deviation score (SDS) for wrist breadth was evaluated as a predictor of HOMA-IR (log-transformed) before and after adjusting for internal-sample SDSs for BMI, waist circumference (WC), and total body fat (TBF) from dual energy X-ray absorptiometry, in addition to age, sex, Tanner stage, and birth year, using generalized estimating equations. Results Before additional adiposity adjustment, we found a significant positive association between wrist breadth SDS and log-transformed HOMA-IR (β = 0.13; 95%CI: 0.09–0.17), which remained significant after adjusting for TBF SDS (β = 0.09; 95%CI: 0.05–0.13; P < 0.001), BMI SDS (β = 0.06; 95%CI: 0.02–0.10; P = 0.007), and WC SDS (β = 0.06; 95%CI: 0.02–0.09; P = 0.005). Conclusions Further work is needed to determine whether simple frame size measures such as wrist breadth may be useful markers of metabolic risk. PMID:23897560

  4. Studies Of Coherent Synchrotron Radiation And Longitudinal Space Charge In The Jefferson Lab FEL Driver

    SciTech Connect

    Tennant, Christopher D.; Douglas, David R.; Li, Rui; Tsai, C.-Y.

    2014-12-01

    The Jefferson Laboratory IR FEL Driver provides an ideal test bed for studying a variety of beam dynamical effects. Recent studies focused on characterizing the impact of coherent synchrotron radiation (CSR) with the goal of benchmarking measurements with simulation. Following measurements to characterize the beam, we quantitatively characterized energy extraction via CSR by measuring beam position at a dispersed location as a function of bunch compression. In addition to operating with the beam on the rising part of the linac RF waveform, measurements were also made while accelerating on the falling part. For each, the full compression point was moved along the backleg of the machine and the response of the beam (distribution, extracted energy) measured. Initial results of start-to-end simulations using a 1D CSR algorithm show remarkably good agreement with measurements. A subsequent experiment established lasing with the beam accelerated on the falling side of the RF waveform in conjunction with positive momentum compaction (R56) to compress the bunch. The success of this experiment motivated the design of a modified CEBAF-style arc with control of CSR and microbunching effects.

  5. Longitudinal stabilisation of bunched beams in a FEL storage ring

    NASA Astrophysics Data System (ADS)

    Migliorati, M.; Palumbo, L.; Dattoli, G.; Mezi, L.; Renieri, A.; Voykov, G. K.

    1997-02-01

    Experimental observations on FEL Storage Rings (Aco, Super-Aco, VEPP3, TERAS) have shown that in a storage ring with an operating FEL there is a mutual effect between the FEL operational mode and the beam longitudinal distribution. The main effects are the birth of a macro-temporal structure of the FEL radiation and a suppression of the synchrotron sidebands, evidence of beam stabilisation against the microwave instabilities. In this paper we discuss the main features of the beam dynamics analysed with a simulation code recently developed, which includes the FEL-beam interaction. Furtherly, we propose an heuristic model which enable to describe in a simple way the overall system.

  6. Extending the History of Child Obesity in the United States: The Fels Longitudinal Study, Birth Years 1930 to 1993

    PubMed Central

    von Hippel, Paul T.; Nahhas, Ramzi W.

    2013-01-01

    Objective Little is known about the prevalence of child obesity in the U.S. before the first national survey in 1963. There is disagreement about whether the obesity epidemic is entirely a recent phenomenon or a continuation of longstanding trends. Methods We analyze the BMIs of 1,116 children who participated in the Fels Longitudinal Study near Dayton, Ohio. Children were born between 1930 and 1993 and measured between 3 and 18 years of age. Results Between the birth cohorts of 1930 and 1993, the prevalence of obesity rose from 0% to 14% among boys and from 2% to 12% among girls. The prevalence of overweight rose from 10% to 28% among boys and from 9% to 21% among girls. The mean BMI Z-score rose from +0.25 to +0.72 among boys and from −0.11 to +0.26 among girls. Among boys, all these increases began after birth year 1970. Among girls, obesity began to rise after birth year 1970, but overweight and BMI Z-scores were already rising as early as the 1930s and 1940s. Conclusions Most of the results suggest that the child obesity epidemic was recent and sudden. The recency of the epidemic offers some hope that it may be reversed. PMID:23512972

  7. Evolution of longitudinal modes in low voltage FEL

    SciTech Connect

    Stuart, R.A.; Al-Shamma`a, A.; Shaw, A.

    1995-12-31

    A low voltage FEL operating at 130 kV which can be run cw with a continuous electron beam current level up to 12 mA has been constructed for the X-Band microwave range (8-12 GHz). In this poster, we will report on the dependence on time, after the electron beam is switched on, of the growth and competition of those longitudinal modes in the cavity having nett gain.

  8. Presentation, heritability, and genome-wide linkage analysis of the midchildhood growth spurt in healthy children from the Fels Longitudinal Study.

    PubMed

    Towne, Bradford; Williams, Kimberly D; Blangero, John; Czerwinski, Stefan A; Demerath, Ellen W; Nahhas, Ramzi W; Dyer, Thomas D; Cole, Shelley A; Lee, Miryoung; Choh, Audrey C; Duren, Dana L; Sherwood, Richard J; Chumlea, William Cameron; Siervogel, Roger M

    2008-12-01

    Growth is a complex process composed of distinct phases over the course of childhood. Although the pubertal growth spurt has received the most attention from auxologists and pediatricians, the midchildhood growth spurt has been less well studied. The midchildhood growth spurt refers to a relatively small increase in growth velocity observed in some, but not necessarily all, children in early to middle childhood. If present, the midchildhood growth spurt typically occurs sometime between the ages of 4 and 8 years, well before the onset of the far more pronounced pubertal growth spurt. In this study we used a triple logistic curve-fitting method to fit individual growth curves to serial stature data from 579 healthy participants in the Fels Longitudinal Study, 479 of whom have been genotyped for about 400 short tandem repeat (STR) markers spanning the genome. We categorized individuals according to the presence or absence of a midchildhood growth spurt and then conducted heritability and genome-wide linkage analyses on the dichotomous trait. In the total sample of 579 individuals, 336 (58%) were found to have evidence of having had a midchildhood growth spurt. There was a marked sex difference in presence of the midchildhood growth spurt, however, with 232 of the 293 males (79%) having had a midchildhood growth spurt but just 104 of the 286 females (36%) having had one. Presence of a midchildhood growth spurt was found to have a significant heritability of 0.37 +/- 0.14 (p = 0.003). Two quantitative trait loci with suggestive LOD scores were found: one at 12 cM on chromosome 17p13.2 (LOD = 2.13) between markers D17S831 and D17S938 and one at 85 cM on chromosome 12q14 (LOD = 2.06) between markers D12S83 and D12S326. PMID:19728540

  9. The FERMI @ Elettra Technical Optimization Study: General Layoutand Parameters and Physics Studies of Longitudinal Space Charge, theSpreader, the Injector, and Preliminary FEL Performance

    SciTech Connect

    Byrd, John; Corlett, John; Doolittle, Larry; Fawley, William; Lidia, Steven; Penn, Gregory; Ratti, Alex; Staples, John; Wilcox,Russell; Wurtele, Jonathan; Zholents, Alexander

    2005-09-01

    The FERMI {at} Elettra facility will make use of the existing GeV linac at Sincrotrone Elettra, which will become available for dedicated FEL applications following the completion of construction of a new injector booster complex for the storage ring. With a new rf photocathode injector, and some additional accelerating sections, this linac will be capable of providing high brightness bunches at 1.2 GeV and up to 50 Hz repetition rates.

  10. Optimization Studies of the FERMI at ELETTRA FEL Design

    SciTech Connect

    De Ninno, Giovanni; Fawley, William M.; Penn, Gregory E.; Graves,William

    2005-08-25

    The FERMI at ELETTRA project at Sincotrone Trieste involves two FEL's, each based upon the principle of seeded harmonic generation and using the existing ELETTRA injection linac at 1.2 GeV beam energy. Scheduled to be completed in 2008, FEL-1 will operate in 40-100 nm wavelength range and will involve one stage of harmonic up-conversion. The second undulator line, FEL-2, will begin operation two years later in the 10-40 nm wavelength range and use two harmonic stages operating as a cascade. The FEL design assumes continuous wavelength tunability over the full wavelength range, and polarization tunability of the output radiation including vertical or horizontal linear as well as helical polarization. The design considers focusing properties and segmentation of realizable undulators and available input seed lasers. We review the studies that have led to our current design. We present results of simulations using GENESIS and GINGER simulation codes including studies of various shot-to-shot fluctuations and undulator errors. Findings for the expected output radiation in terms of the power, transverse and longitudinal coherence are reported.

  11. Design study of a longer wavelength FEL for FELIX

    SciTech Connect

    Lin, L.; Oepts, D.; Meer, A.F.G. van der

    1995-12-31

    We present a design study of FEL3, which will extend the FELIX spectral range towards a few hundred microns. A rectangular waveguide will be used to reduce diffraction losses. Calculations show that with a waveguide gap of 1 cm, only one sinusoidal mode along the guided direction can exist within the FEL gain bandwidth, thus excluding group velocity dispersion and lengthening of short radiation pulses. To incorporate FEL3 in the existing FELIX facility, two options are being considered: to combine FEL3 with FEL1 by insertion of a waveguide into FEL1, and to build a dedicated third beam line for FEL3 after the two linacs. Expected FEL performance: gain, spectrum, power, pulse shape, etc., will be presented based on numerical simulations.

  12. Longitudinal Space Charge Effects in the JLAB IR FEL SRF LINAC

    SciTech Connect

    C. Hernandez-Garcia; K. Beard; C. Behre; S. Benson; G. Biallas; J. Boyce; D. Douglas; H. F. Dylla; R. Evans; A. Grippo; J. Gubeli; D. Hardy; K. Jordan; L. Merminga; G. Neil; J. Preble; Michelle D. Shinn; T. Siggins; R. Walker; G. P. Williams; B. Yunn; S. Zhang

    2004-09-01

    Observations of energy spread asymmetry when operating the Linac on either side of crest and longitudinal emittance growth have been confirmed by extending PARMELA simulations from the injector to the end of the first SRF Linac module. The asymmetry can be explained by the interaction of the accelerating electric field with that from longitudinal space charge effects within the electron bunch. This can be a major limitation to performance in FEL accelerators.

  13. Electron beam effects in a UV FEL

    SciTech Connect

    Wong, R.K.; Blau, J.; Colson, W.B.

    1995-12-31

    At the Continuous Electron Beam Accelerator Facility (CEBAF), a free electron laser (FEL) is designed to produce ultraviolet (UV) light. A four-dimensional FEL simulation studies the effects of betatron oscillations, external focusing, and longitudinal pulse compression of the electron beam on the FEL performance.

  14. LONGITUDINAL PHASE SPACE CHARACTERIZATION OF ELECTRON BUNCHES AT THE JLAB FEL FACILITY

    SciTech Connect

    Shukui Zhang; Stephen Benson; David Douglas; David Hardy; George Neil; Michelle D. Shinn

    2006-08-27

    We report longitudinal phase space measurements of short electron bunches at the 10kW Free-Electron Laser Facility at Jefferson Lab using broadband synchrotron radiation and a remotely controlled fast streak camera. Accurate measurements are possible because the optical transport system uses only reflective components that do not introduce dispersion. The evolution of longitudinal phase space of the electron beam can be observed in real time while phases of accelerator RF components are being adjusted. This fast and efficient diagnostic enhances the suite of machine setup tools available to JLab FEL operators and applies to other accelerators. The results for certain beam setups will be presented.

  15. Study of waveguide resonators for FEL operating at submillimeter wavelengths

    SciTech Connect

    Yakover, I.M.; Pinhasi, Y.; Gover, A.

    1995-12-31

    This paper presents theoretical results of waveguide resonator study for FEL operating at the submillimeter wavelength region. Because of increased ohmic losses it is harder to obtain high Q waveguide cavities at these wavelengths. The following unconventional multimode waveguides: metal-dielectric, corrugated and curved parallel plates, were considered. The type and structure of the operating modes were determined and their attenuation constant, effective mode area and wave impedance were calculated. On the basis of this analysis small-signal gain simulations were made. We have performed a parametric study of the various FEL oscillator cavity designs based on the parameters of the Israeli Tandem FEL experiment. It was found that an FEL utilizing unconventional waveguides has much better performance in comparison to an FEL based on conventional multimode rectangular and circular waveguides. In particular, promising design parameters for a sub-mm wavelength FEL utilizing a metal-dielectric waveguide were identified: gain of 45%/Amp and ohmic losses of 2% at frequency 300 GHz, and gain of 20%/Amp and ohmic losses 1% at frequency 675 GHz.

  16. R&D Requirements, RF Gun Mode Studies, FEL-2 Steady-StateStudies, Preliminary FEL-1 Time-Dependent Studies, and Preliminary LayoutOption Investigation

    SciTech Connect

    Byrd, John; Corlett, John; Doolittle, Larry; Fawley, William; Lidia, Steven; Penn, Gregory; Ratti, Alex; Staples, John; Wilcox Russell; Wurtele, Jonathan; Zholents, Alexander

    2005-10-01

    This report constitutes the third deliverable of LBNLs contracted role in the FERMI {at} Elettra Technical Optimization study. It describes proposed R&D activities for the baseline design of the Technical Optimization Study, initial studies of the RF gun mode-coupling and potential effects on beam dynamics, steady-state studies of FEL-2 performance to 10 nm, preliminary studies of time-dependent FEL-1 performance using electron bunch distribution from the start-to-end studies, and a preliminary investigation of a configuration with FEL sinclined at a small angle from the line of the linac.

  17. Design study of a 7 kW, visible wavelength FEL

    SciTech Connect

    Chen, S.C.; Danly, B.G.; Temkin, R.J.; Wurtele, J.; Yang, B.

    1990-01-01

    The MIT Lincoln Laboratory is investigating the possibility of building a free electron laser (FEL) operating at an average power of about 7 kW at wavelengths of 500--600 nm. Additional specifications for the FEL include a bandwidth of less than 0.1 cm{sup {minus}1} and a micropulse separation of less than 10 ns. The design study has investigated the basic design parameters of the FEL including an analysis of the electron accelerator, beam line, wiggler and optical cavity. A nonlinear model of the FEL has been used to calculate the FEL gain and efficiency. The required output power appears achievable from an FEL operating at more than 1% efficiency with a conventional RF accelerator. Details of the FEL design are presented in this report which represent the final report for the year from September 1, 1989 to August 31, 1990. 28 refs., 13 figs., 5 tabs.

  18. Studies of Resistive Wall Heating at JLAB FEL

    SciTech Connect

    Li, Rui; Benson, Stephen V.

    2013-06-01

    When the JLAB FEL is under CW operation, it had been observed that temperature rises over the wiggler vacuum chamber, presumably as the result of the power deposition on the resistive wall of the wiggler chamber. Previous analyses have been done on the resistive wall impedance for various cases, such as DC, AC, and anomalous skin effects*. Here we report an investigation on the beam kinetic energy losses for each of these cases. This study includes the non-ultrarelativistic effect on resistive wall loss, for both round pipe and parallel plates. We will present the comparison of our results with the measured data obtained during CW operation of the JLAB FEL. Other possible factors contributing to the measured heating will also be discussed.

  19. Feasibility studies of a compact mm-wave linac FEL

    SciTech Connect

    Nassiri, A.; Kustom, R.L.; Kang, Y.W.; Song, J.

    1995-12-31

    Short wavelength FELs impose stringent requirements on the quality of the electron beams. The key factor in obtaining a single-pass UV or x-ray FEL is the generation of small emittance electron beams with ultra-high brightness. The pioneering work at Los Alamos National Laboratory in the last decade has resulted in a dramatic improvement in the production of high electron beam brightness and small beam emittance using rf photocathode gun. The lower bound on the emittance of a 1-nC bunch without any emittance compensation is on the order of 3 {pi} mm-mrad. This is well within the emittance requirement being considered here. Although the original R&D work at Argonne, in collaboration with the University of Illinois at Chicago and University of Wisconsin-Madison, has produced encouraging results in the area of rf structure design, x-ray mask fabrication, and LIGA processing (Lithography, Electroforming, and Molding), the goal to prove feasibility has not yet been achieved. In this paper, we will present feasibility studies for a compact single-pass mm-linac FEL based on LIGA technology. This system will consist of a photocathode rf gun operated at 30 GHz, a 50-MeV superconducting constant gradient structure operated at 60 GHz, and a microundulator with 1-mm period.

  20. Numerical study of X-ray FELS including quantum fluctuation

    NASA Astrophysics Data System (ADS)

    Reiche, S.; Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

    1997-06-01

    One of the fundamental limitations towards achieving very short wavelength in a self amplified spontaneous emission free electron laser (SASE FEL) is connected with the energy diffusion in the electron beam due to quantum fluctuations of undulator radiation. Parameters of the LCLS and TESLA X-ray FEL projects are very close to this limit and there exists necessity in upgrading FEL simulation codes for optimization of SASE FEL for operation at a shortest possible wavelength. In this report we describe a one-dimensional FEL simulation code taking into account the effects of incoherent undulator radiation. Using similarity techniques we have calculated universal functions describing degradation of the FEL process due to quantum fluctuations of undulator radiation.

  1. Study of CSR Effects in the Jefferson Laboratory FEL Driver

    SciTech Connect

    Hall, C. C.; Biedron, S.; Burleson, Theodore A.; Milton, Stephen V.; Morin, Auralee L.; Benson, Stephen V.; Douglas, David R.; Evtushenko, Pavel E.; Hannon, Fay E.; Li, Rui; Tennant, Christopher D.; Zhang, Shukui; Carlsten, Bruce E.; Lewellen, John W.

    2013-08-01

    In a recent experiment conducted on the Jefferson Laboratory IR FEL driver the effects of Coherent Synchrotron Radiation (CSR) on beam quality were studied. The primary goal of this work was to explore CSR output and effect on the beam with variation of the bunch compression in the IR chicane. This experiment also provides a valuable opportunity to benchmark existing CSR models in a system that may not be fully represented by a 1-D CSR model. Here we present results from this experiment and compare to initial simulations of CSR in the magnetic compression chicane of the machine. Finally, we touch upon the possibility for CSR induced microbunching gain in the magnetic compression chicane, and show that parameters in the machine are such that it should be thoroughly damped.

  2. WISCONSIN LONGITUDINAL STUDY (WLS)

    EPA Science Inventory

    The Wisconsin Longitudinal Study (WLS) is a long-term study of a random sample of 10,317 men and women who graduated from Wisconsin high schools in 1957. The WLS provides an opportunity to study of the life course, intergenerational transfers and relationships, family functioning...

  3. Progress at the Jefferson Laboratory FEL

    SciTech Connect

    Tennant, Christopher

    2009-01-01

    As the only currently operating free electron laser (FEL) based on a CW superconducting energy recovering linac (ERL), the Jefferson Laboratory FEL Upgrade remains unique as an FEL driver. The present system represents the culmination of years of effort in the areas of SRF technology, ERL operation, lattice design, high power optics and DC photocathode gun technology. In 2001 the FEL Demo generated 2.1 kW of laser power. Following extensive upgrades, in 2006 the FEL Upgrade generated 14.3 kW of laser power breaking the previous world record. The FEL Upgrade remains a valuable testbed for studying a variety of collective effects, such as the beam breakup instability, longitudinal space charge and coherent synchrotron radiation. Additionally, there has been exploration of operation with lower injection energy and higher bunch charge. Recent progress and achievements in these areas will be presented, and two recent milestones â installation of a UV FEL and establishment of a DC gun test s

  4. Parameter study of the VUV-FEL at the Tesla Test Facility

    SciTech Connect

    Brefeld, W.; Faatz, B.

    1995-12-31

    In this contribution we present a detailed study of the influence of the electron beam and machine parameters on the performance of the TTF VUV FEL, which is in its design stage at DESY. The TTF FEL will be a 6 nm SASE device operating with the beam provided by the Tesla Test Facility superconducting linac, driven by an rf photcathode gun. The FEL output power and saturation length have been assessed with the use of different 2D3-D steady state simulation codes. The parameter range over which the FEL would reach saturation within the specified undulator length of 25 to 30 m have been determined and checked against semi-analytical expressions.

  5. Coherence and linewidth studies of a 4-nm high power FEL

    NASA Astrophysics Data System (ADS)

    Fawley, W. M.; Sessler, A. M.; Scharlemann, E. T.

    1993-05-01

    Recently the SSRL/SLAC and its collaborators elsewhere have considered the merits of a 2 to 4-nm high power FEL utilizing the SLAC linac electron beam. The FEL would be a single pass amplifier excited by spontaneous emission rather than an oscillator, in order to eliminate the need for a soft X-ray resonant cavity. We have used GINGER, a multifrequency 2D FEL simulation code, to study the expected linewidth and coherence properties of the FEL, in both the exponential and saturated gain regimes. We present results concerning the effective shot noise input power and mode shape, the expected subpercent output line widths, photon flux, and the field temporal and spatial correlation functions. We also discuss the effects of tapering the wiggler upon the output power and line width.

  6. Numerical study of the 3-D effect on FEL performance and its application to the APS LEUTL FEL

    SciTech Connect

    Chae, Y.C.

    1998-09-01

    A Low-Energy Undulator Test Line (LEUTL) is under construction at the Advanced Photon Source (APS). In LEUTL periodic focusing is provided by external quadrupoles. This results in an elliptical beam with its betatron oscillation envelope varying along the undulators. The free-electron laser (FEL) interaction with such a beam will exhibit truly 3-D effects. Thus the investigation of 3-D effects is important in optimizing the FEL performance. The programs GINGER and TDA3D, coupled with theoretically known facts, have been used for this purpose. Both programs are fully 3-D in moving the particle, but model the interaction between particles and axially symmetric electromagnetic waves. Even though TDA3D can include a few azimuthal modes in the interaction, it is still not a fully 3-D FEL code. However, they show that these 2-D programs can still be used for an elliptical beam whose aspect ratio is within certain limits. The author presents numerical results of FEL performance for the circular beam, the elliptical beam, and finally for the beam in the realistic LEUTL lattice.

  7. Experimental study of the interaction of THz radiation FEL with the atmosphere and water droplet aerosol

    NASA Astrophysics Data System (ADS)

    Matvienko, G. G.; Lisenko, A. A.; Babchenko, S. V.; Kargin, B. A.; Kablukova, E. G.; Kubarev, V. V.

    2015-11-01

    The interaction of radiation of the Novosibirsk Free Electron Laser (FEL) at a wavelength of 130 μm in the atmospheric transmission window with a model aerosol cloud having the known droplet size distribution function has been studied experimentally. The experimental findings are compared with theoretical calculations obtained from solution of the lidar equation for the conditions of the experiment.

  8. Transverse effects in UV FELs

    SciTech Connect

    Small, D.W.; Wong, R.K.; Colson, W.B.

    1995-12-31

    In an ultraviolet Free Electron Laser (UV FEL), the electron beam size can be approximately the same as the optical mode size. The performance of a UV FEL is studied including the effect of emittance, betatron focusing, and external focusing of the electron beam on the transverse optical mode. The results are applied to the Industrial Laser Consortium`s UV FEL.

  9. A Design Study of a FIR/THz-FEL for High Magnetic Field Research

    SciTech Connect

    Tecimer, M; Brunel, L C; Tol, J van; Neil, G

    2006-09-01

    Presently a conceptual design work for a NIR-FIR FEL system at the NHMFL/FSU is being undertaken. The system is intended to combine high magnetic field research with an intense, tuneable photon source, spanning the spectral region ~2–1000 microns. Here, we present a design study involving the FIR/THz part of the NHMFL FEL design proposal. The suggested long-wavelength FEL encompasses in the first phase a thermionic injector (similar to that in use at the Forschungszentrum-Rossendorf ELBE facility) with a planned ~2 mA average current and a ~10 MeV superconducting rf linac module operating at 1.3 GHz. The broadband outcoupling over the envisaged FIR/THz spectral range (100–1100 microns) is accomplished by adopting a single (variable height slot) outcoupler in a waveguided cavity. Besides the performance predictions of the suggested long-wavelength FEL, techniques for the generation of high peak power, nanoseconds long THz pulses (for magnetic resonance applications) are also reported.

  10. Transverse-coherence properties of the FEL at the LCLS

    SciTech Connect

    Ding, Yuantao; Huang, Zhirong; Ocko, Samuel A.; /MIT, Cambridge, Dept. Phys.

    2010-09-02

    The recently commissioned Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is now operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources. Understanding of coherence properties of the radiation from SASE FELs at LCLS is of great practical importance for some user experiments. We present the numerical analysis of the coherence properties at different wavelengths based on a fast algorithmusing ideal and start-end simulated FEL fields. The sucessful commissioning and operation of the linac coherent light source (LCLS) [1] has demonstrated that the x-ray free-electron laser (FEL) has come of age; these types of x-ray sources are poised to revolutionize the ultra-fast x-ray sciences. The LCLS and other hard x-ray FELs under construction are based on the principle of self-amplified spontaneous emission (SASE) [2, 3], where the amplification process starts from the shot noise in the electron beam. A large number of transverse radiation modes are also excited when the electron beam enters the undulator. The FEL collective instability in the electron beam causes the modulation of the electron density to increase exponentially, and after sufficient undulator distances, a single transverse mode starts to dominate. As a result, SASE FEL is almost fully coherent in the transverse dimension. Understanding of transverse coherence properties of the radiation from SASE FELs is of great practical importance. The longitudinal coherence properties of SASE FELs have been studied before [4]. Some studies on the transverse coherence can be found in previous papers, for example, in ref. [5, 6, 7, 8, 9]. In this paper, we first discuss a new numerical algorithm based on Markov chain Monte Carlo techniques to calculate the FEL transverse coherence. Then we focus on the numerical analysis of the LCLS FEL transverse coherence.

  11. NATIONAL HIGH MAGENTIC FIELD LABORATORY FEL INJECTOR DESIGN CONSIDERATION

    SciTech Connect

    Pavel Evtushenko; Stephen Benson; David Douglas; George Neil

    2007-06-25

    A Numerical study of beam dynamics was performed for two injector systems for the proposed National High Magnetic Field Laboratory at the Florida State University (FSU) Free Electron Laser (FEL) facility. The first considered a system consisting of a thermionic DC gun, two buncher cavities operated at 260 MHz and 1.3 GHz and two TESLA type cavities, and is very similar to the injector of the ELBE Radiation Source. The second system we studied uses a DC photogun (a copy of JLab FEL electron gun), one buncher cavity operated at 1.3 GHz and two TESLA type cavities. The study is based on PARMELA simulations and takes into account operational experience of both the JLab FEL and the Radiation Source ELBE. The simulations predict the second system will have a much smaller longitudinal emittance. For this reason the DC photo gun based injector is preferred for the proposed FSU FEL facility.

  12. Studies of a Linac Driver for a High Repetition Rate X-Ray FEL

    SciTech Connect

    Venturini, M.; Corlett, J.; Doolittle, L.; Filippetto, D.; Papadopoulos, C.; Penn, G.; Prosnitz, D.; Qiang, J.; Reinsch, M.; Ryne, R.; Sannibale, F.; Staples, J.; Wells, R.; Wurtele, J.; Zolotorev, M.; Zholents, A.

    2011-06-01

    We report on on-going studies of a superconducting CW linac driver intended to support a high repetition rate FEL operating in the soft x-rays spectrum. We present a pointdesign for a 1.8 GeV machine tuned for 300 pC bunches and delivering low-emittance, low-energy spread beams as needed for the SASE and seeded beamlines.

  13. JINR test facility for studies FEL bunching technique for CLIC driving beam

    SciTech Connect

    Dolbilov, G.V.; Fateev, A.A.; Ivanov, I.N.

    1995-12-31

    SILUND-21 linear induction accelerator (energy up to 10 MeV, peak current about of 1 kA, pulse duration 50 - 70 ns) is constructed at JINR in the framework of experimental program to study free electron laser physics, a problem of two-beam acceleration and microwave electronics. In this paper we present project of an experiment to adopt the FEL bunching technique for generation of the CLIC driving beam.

  14. Parameter Selection and Longitudinal Phase Space Simulation for a Single Stage X-Band FEL Driver at 250 MeV

    SciTech Connect

    Sun, Yipeng; Raubenheimer, Tor; Wu, Juhao; /SLAC

    2011-08-19

    Hard x-ray Free electron lasers (FEL) are being built or proposed at many accelerator laboratories as it supports wide range of applications in many aspects. Most of the hard x-ray FEL design is similar with the SLAC Linac Coherent Light Source (LCLS), which features a two (or multiple) stage bunch compression. For the first stage of the bunch compression, usually the beam is accelerated in a lower-frequency RF section (such as S-band for LCLS), and then the longitudinal phase space is linearized by a higher-frequency RF section (harmonic RF, such as X-band for LCLS). In this paper, a compact hard x-ray FEL design is proposed, which is based on X-band RF acceleration and eliminating the need of a harmonic RF. The parameter selection and relation is discussed, and the longitudinal phase space simulation is presented. The FEL coherence condition of the electron beam in the undulators requires a large charge density, a small emittance and small energy spread. The RMS electron bunch length from the injector is in the ps scale, with a bunch charge in the range of hundreds pC to several nC, which means that the current is roughly 0.1 kA. According to the requirement from soft x-ray lasing and hard x-ray lasing, a peak current of 1 kA and 3 kA is needed respectively. Thus the bunch has to be compressed. Usually a two stage bunch compression or multipole stage bunch compression is adopted. The z-correlated energy chirp is normally established by letting the beam pass through a section of RF cavities, with a RF phase off crest. As stated above, S-band RF (3 GHz) acceleration could be applied in this section. Due to the nature of RF acceleration wave, the chirp on the bunch is not linear, but has the RF curvature on it. In order to linearize the energy chirp, a harmonic RF section with higher frequency is needed. For LCLS a short X-band RF section (12 GHz) is used which is a fourth order harmonic. The linearized bunch is then passing by a dispersive region, in which the

  15. LONGITUDINAL COHORT METHODS STUDIES

    EPA Science Inventory

    Accurate exposure classification tools are required to link exposure with health effects in epidemiological studies. Exposure classification for occupational studies is relatively easy compared to predicting residential childhood exposures. Recent NHEXAS (Maryland) study articl...

  16. LONGITUDINAL STUDY OF AGING (LSOA)

    EPA Science Inventory

    The Longitudinal Study of Aging (LSOA) is a collaborative effort of the National Center for Health Statistics (NCHS) and the National Institute on Aging (NIA). The Supplement on Aging (SOA), conducted in conjunction with the 1984 National Health Interview Survey (NHIS), served as...

  17. SIAST Longitudinal Study.

    ERIC Educational Resources Information Center

    Sarkar, Gerlinde

    In 1991, the Saskatchewan Institute of Applied Science and Technology (SIAST) initiated a study of factors affecting student persistence, finding that high employment rates in particular sectors were related to higher rates of student attrition. In 1994, a follow-up study was conducted of the career/educational paths of 1,498 respondents from the…

  18. Three-dimensional study of the multi-cavity FEL

    SciTech Connect

    Krishnagopal, S.; Kumar, V.

    1995-12-31

    The Multi-Cavity Free-Electron Laser has been proposed earlier, as a new configuration to obtain short, intense pulses of radiation, the key idea being to pre-bunch the electron beam in a number of very short cavities. Those studies were one-dimensional. Here we use three-dimensional simulations to study the viability of this concept when three-dimensional effects are included, particularly with regard to the transverse modes of the optical beam.

  19. Resonantly enhanced multiphoton ionization under XUV FEL radiation: a case study of the role of harmonics

    NASA Astrophysics Data System (ADS)

    Nikolopoulos, G. M.; Lambropoulos, P.

    2015-12-01

    We provide a detailed quantitative study of the possible role of a small admixture of harmonics on resonant two-photon ionization. The motivation comes from the occasional presence of 2nd and 3rd harmonics in FEL radiation. We obtain the dependence of ionic yields on the intensity of the fundamental, the percentage of 2nd harmonic and the detuning of the fundamental from resonance. Having examined the cases of one and two intermediate resonances, we arrive at results of general validity and global behaviour, showing that even a small amount of harmonic may seem deceptively innocuous.

  20. Tapered undulator for SASE FELs

    SciTech Connect

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2001-09-14

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission (SASE), where the radiation tends to have a relatively broad bandwidth, limited temporal phase coherence, and large amplitude fluctuations. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of a tapered undulator for parameters corresponding to the existing Argonne low-energy undulator test line (LEUTL) FEL. We also study possible tapering options for proposed x-ray FELs such as the Linac Coherent Light Source (LCLS).

  1. The Importance of Longitudinal Studies

    NASA Astrophysics Data System (ADS)

    Knezek, Patricia

    2014-01-01

    It has been eight years since the AAS Council unanimously endorsed the document, known as "Equity Now: The Pasadena Recommendations for Gender Equality in Astronomy," in January 2005. This document was the main product of the conference entitled “Women in Astronomy II: Ten Years After” (WIA II), held in June 2003 in Pasadena, CA. One of the key recommendations represented in that document was the need for a longitudinal study of astronomers. It was recognized that in order to understand our own field, how it is evolving, and the impact on individuals, we need to track people over time. I will discuss the fundamental questions that led to the recommendation, and set the stage for the current (ongoing) longitudinal study.

  2. Super ACO FEL oscillation at 300 nm

    NASA Astrophysics Data System (ADS)

    Nutarelli, D.; Garzella, D.; Renault, E.; Nahon, L.; Couprie, M. E.

    2000-05-01

    Some recent improvements, involving both the optical cavity mirrors and the positron beam dynamics in the storage ring, have allowed us to achieve a laser oscillation at 300 nm on the Super ACO Storage Ring FEL. The Super ACO storage ring is operated at 800 MeV which is the nominal energy for the usual synchrotron radiation users, and the highest energy for a storage ring FEL. The lasing at 300 nm could be kept during 2 h per injection, with a stored current ranging between 30 and 60 mA. The FEL characteristics are presented here. The longitudinal stability and the FEL optics behaviour are also discussed.

  3. Two FEL`s in one

    SciTech Connect

    Epp, V.; Nikitin, M.

    1995-12-31

    A new scheme for a FEL operation is proposed. The conventional principle of FEL operation is means that the electron bunch passes through the interaction area of FEL only in one direction. We suggest another possible layout which implies that the electron bunch makes a turn after leaving the wiggler and entries the wiggler at the same end. Actually the wiggler is a kind of a bridge between two storage rings. The electron bunches on the orbit are expected to be adjusted in the way that after one of them leaves the wiggler, another one enters in the opposite direction and in the proper phase with the wave pulse emitted by the previous bunch. So the electron bunch comes in interaction with the amplified electromagnetic wave in both directions i.e. twice per period. It is especially important for the short wavelength FELs, because each reflection from the mirror causes a significant losses of the wave magnitude. The proposed design gives one interaction per each reflection instead of one interaction per two reflections in the traditional scheme. Another way to realize the suggested principle of operating is to insert the wiggler in the electron-positron storage ring. But this layout can be less efficient because of low intensity of the positron beam. The comparison study of radiation from different types of described double wigglers is fulfilled. The synchronization problems are discussed in this paper.

  4. Sensitivity and alternative operating point studies on a high charge CW FEL injector test stand at CEBAF

    SciTech Connect

    Liu, H.; Kehne, D.; Benson, S.

    1995-12-31

    A high charge CW FEL injector test stand is being built at CEBAF based on a 500 kV DC laser gun, a 1500 MHz room-temperature buncher, and a high-gradient ({approx}10 MV/m) CEBAF cryounit containing two 1500 MHz CEBAF SRF cavities. Space-charge-dominated beam dynamics simulations show that this injector should be an excellent high-brightness electron beam source for CW UV FELs if the nominal parameters assigned to each component of the system are experimentally achieved. Extensive sensitivity and alternative operating point studies have been conducted numerically to establish tolerances on the parameters of various injector system components. The consequences of degraded injector performance, due to failure to establish and/or maintain the nominal system design parameters, on the performance of the main accelerator and the FEL itself are discussed.

  5. Longitudinal study of fingerprint recognition

    PubMed Central

    Yoon, Soweon; Jain, Anil K.

    2015-01-01

    Human identification by fingerprints is based on the fundamental premise that ridge patterns from distinct fingers are different (uniqueness) and a fingerprint pattern does not change over time (persistence). Although the uniqueness of fingerprints has been investigated by developing statistical models to estimate the probability of error in comparing two random samples of fingerprints, the persistence of fingerprints has remained a general belief based on only a few case studies. In this study, fingerprint match (similarity) scores are analyzed by multilevel statistical models with covariates such as time interval between two fingerprints in comparison, subject’s age, and fingerprint image quality. Longitudinal fingerprint records of 15,597 subjects are sampled from an operational fingerprint database such that each individual has at least five 10-print records over a minimum time span of 5 y. In regard to the persistence of fingerprints, the longitudinal analysis on a single (right index) finger demonstrates that (i) genuine match scores tend to significantly decrease when time interval between two fingerprints in comparison increases, whereas the change in impostor match scores is negligible; and (ii) fingerprint recognition accuracy at operational settings, nevertheless, tends to be stable as the time interval increases up to 12 y, the maximum time span in the dataset. However, the uncertainty of temporal stability of fingerprint recognition accuracy becomes substantially large if either of the two fingerprints being compared is of poor quality. The conclusions drawn from 10-finger fusion analysis coincide with the conclusions from single-finger analysis. PMID:26124106

  6. DESIGN STUDY OF COMPACT MEGA-WATT CLASS FEL AMPLIFIER BASED ON THE VISA UNDULATOR.

    SciTech Connect

    WATANABE, T.; LIU, D.; MURPHY, J.B.; PINAYEV, I.; ROSE, J.; SHAFTAN, T.; SKARITKA, J.; TANABE, T.; TSANG, T.; WANG, X.J.; YU, L.H.

    2005-08-21

    The strong focusing VISA undulator is presented in this report. The proposed FEL will operate at the 1 {micro}m water window. Extensive simulations were performed to optimize an FEL amplifier based on the two-meter long VISA undulator which has a period of 1.8 cm and an undulator parameter K = 1.26. The betatron function inside the VISA undulator is about 30 cm. For an electron beam with a peak current {approx}1 kA and a normalized emittance of 5 mm-mrad, the FEL peak power can exceed 1 GW within the 2 m VISA undulator using a 5 kW peak power seed laser. Such a device can produce a megawatt of average power for a 700 MHz rep rate. The transverse distribution of the FEL radiation along the undulator, as well as after the undulator, is explored by numerical simulation. The FEL power density at 5 m downstream from the undulator is less than 100 kW/cm{sup 2} for this MW-class FEL. We will also discuss the feasibility of an experimental demonstration of the laser seeded FEL amplifier based on the 2-m VISA undulator at the NSLS Source Development Lab (SDL).

  7. Fears in Czech Adolescents: A Longitudinal Study

    ERIC Educational Resources Information Center

    Michalcáková, Radka; Lacinová, Lenka; Kyjonková, Hana; Bouša, Ondrej; Jelínek, Martin

    2013-01-01

    The present study investigates developmental patterns of fear in adolescence. It is based on longitudinal data collected as a part of the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) project. A total of 186 Czech adolescents (43% girls) were assessed repeatedly at the age of 11, 13, and 15 years. The free-response method was…

  8. The Stanford Picosecond FEL Center

    SciTech Connect

    Schwettman, H.A.; Smith, T.I.; Swent, R.L.

    1995-12-31

    In the past two years, FELs have decisively passed the threshold of scientific productivity. There are now six FEL facilities in the United States and Europe, each delivering more than 2000 hours of FEL beam time per year. at the present time approximately 100 papers are published each in referred journals describing optics experiments performed with FELs. Despite the recent success there are important challenges the FEL facilities must address. At Stanford these challenges include: (1) Providing sufficient experimental time at reasonable cost: At Stanford we provide 2000 hours of experimental time per year at a cost of approximately $500 per hour: We are now studying options for markedly increasing experimental time and decreasing cost per hour. (2) Competing effectively with conventional lasers in the mid-IR: Despite the NRC report we do not intend to concede the mid-IR to conventional lasers. FELs are capable of providing optical beams of exceptional quality and stability, and they can also be remarkable flexible devices. Improvements in our superconducting linac driver and our optical beam conditioning systems will dramatically enhance our FEL experimental capabilities. (3) making the transition from first generation to second generation experiments: Important pump-probe and photon echo experiments have been performed at Stanford and others are feasible using present capabilities. None-the-less we are now investing substantial experimental time to improving signal-to-noise and developing other optical cababilities. (4) Extending operation to the far-infrared where the FEL is unique inits capabilities: {open_quotes}FIREFLY{close_quotes} will extend our FEL capabilities to 100 microns. We are now seeking funds for optical instrumentation. (5) Creating and maintaining a good environment for graduate students.

  9. Electron bunch length measurement at the Vanderbilt FEL

    SciTech Connect

    Amirmadhi, F.; Brau, C.A.; Mendenhall, M.

    1995-12-31

    During the past few years, a number of experiments have been performed to demonstrate the possibility to extract the longitudinal charge distribution from spectroscopic measurements of the coherent far-infrared radiation emitted as transition radiation or synchrotron radiation. Coherent emission occurs in a spectral region where the wavelength is comparable to or longer than the bunch length, leading to an enhancement of the radiation intensity that is on the order of the number of particles per bunch, as compared to incoherent radiation. This technique is particularly useful in the region of mm and sub-mm bunch lengths, a range where streak-cameras cannot be used for beam diagnostics due to their limited time resolution. Here we report on experiments that go beyond the proof of principle of this technique by applying it to the study and optimization of FEL performance. We investigated the longitudinal bunch length of the Vanderbilt FEL by analyzing the spectrum of coherent transition radiation emitted by the electron bunches. By monitoring the bunch length while applying a bunch-compression technique, the amount of the compression could be easily observed. This enabled us to perform a systematic study of the FEL performance, especially gain and optical pulse width, as a function of the longitudinal electron distribution in the bunch. The results of this study will be presented and discussed.

  10. Beam Dynamics Study of X-Band Linac Driven X-Ray FELS

    SciTech Connect

    Adolphsen, C.; Limborg-Deprey, C.; Raubenheimer, T.O.; Wu, J.; Sun, Y.; /SLAC

    2011-12-13

    Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band linac drivers. These linacs are more versatile, efficient and compact than ones using S-band or C-band rf technology. For each of the designs, the overall accelerator layout and the shaping of the bunch longitudinal phase space are described briefly. During the last 40 years, the photon wavelengths from linac driven FELs have been pushed shorter by increasing the electron beam energy and adopting shorter period undulators. Recently, the wavelengths have reached the X-ray range, with FLASH (Free-Electron Laser in Hamburg) and LCLS (Linac Coherent Light Source) successfully providing users with soft and hard X-rays, respectively. FLASH uses a 1.2 GeV L-band (1.3 GHz) superconducting linac driver and can deliver 10-70 fs FWHM long photon pulses in a wavelength range of 44 nm to 4.1 nm. LCLS uses the last third of the SLAC 3 km S-band (2.856 GHz) normal-conducting linac to produce 3.5 GeV to 15 GeV bunches to generate soft and hard X-rays with good spatial coherence at wavelengths from 2.2 nm to 0.12 nm. Newer XFELs (at Spring8 and PSI) use C-band (5.7 GHz) normal-conducting linac drivers, which can sustain higher acceleration gradients, and hence shorten the linac length, and are more efficient at converting rf energy to bunch energy. The X-band (11.4 GHz) rf technology developed for NLC/GLC offers even higher gradients and efficiencies, and the shorter rf wavelength allows more versatility in longitudinal bunch phase space compression and manipulation. In the following sections, three different configurations of X-band linac driven XFELs are described that operate from 6 to 14 GeV. The first (LOW CHARGE DESIGN) has an electron bunch charge of only 10 pC; the second (OPTICS LINEARIZATION DESIGN) is based on optics

  11. ADDHEALTH - NATIONAL LONGITUDINAL STUDY OF ADOLESCENT HEALTH

    EPA Science Inventory

    This study provides a comprehensive view of the health and health behaviors of adolescents and the antecedents - personal, interpersonal, familial, and environmental of these outcomes. The study features a longitudinal, multi-level design with independent measurement at the indiv...

  12. Transport studies of LPA electron beam towards the FEL amplification at COXINEL

    NASA Astrophysics Data System (ADS)

    Khojoyan, M.; Briquez, F.; Labat, M.; Loulergue, A.; Marcouillé, O.; Marteau, F.; Sharma, G.; Couprie, M. E.

    2016-09-01

    Laser Plasma Acceleration (LPA) [1] is an emerging concept enabling to generate electron beams with high energy, high peak current and small transverse emittance within a very short distance. The use of LPA can be applied to the Free Electron Laser (FEL) [2] case in order to investigate whether it is suitable for the light amplification in the undulator. However, capturing and guiding of such beams to the undulator is very challenging, because of the large divergence and high energy spread of the electron beams at the plasma exit, leading to large chromatic emittances. A specific beam manipulation scheme was recently proposed for the COXINEL (Coherent X-ray source inferred from electrons accelerated by laser) setup, which makes an advantage from the intrinsically large chromatic emittance of such beams [3]. The electron beam transport is studied using two simulation codes: a SOLEIL in-house one and ASTRA [4]. The influence of the collective effects on the electron beam performance is also examined.

  13. Microbunching Instability Effect Studies and Laser Heater Optimization for the SPARX FEL Accelerator

    SciTech Connect

    Vaccarezza, C.; Chiadroni, E.; Ferrario, M.; Giannessi, L.; Quattromini, M.; Ronsivalle, C.; Venturini, C.; Migliorati, M.; Dattoli, G.

    2010-05-23

    The effects of microbunching instability for the SPARX accelerator have been analyzed by means of numerical simulations. The laser heater counteracting action has been addressed in order to optimize the parameters of the compression system, either hybrid RF plus magnetic chicane or only magnetic, and possibly enhance the FEL performance.

  14. Three-Dimensional Analysis of Frequency-Chirped FELs

    SciTech Connect

    Huang, Z.; Ding, Y.; Wu, J.; /SLAC

    2010-09-14

    Frequency-chirped free-electron lasers (FELs) are useful to generate a large photon bandwidth or a shorter x-ray pulse duration. In this paper, we present a three-dimensional analysis of a high-gain FEL driven by the energy-chirped electron beam. We show that the FEL eigenmode equation is the same for a frequency-chirped FEL as for an undulator-tapered FEL. We study the transverse effects of such FELs including mode properties and transverse coherence.

  15. Pulse Length Control in an X-Ray FEL by Using Wakefields

    SciTech Connect

    Reiche, S.; Pellegrini, Claudio; Emma, P.; /UCLA /SLAC

    2008-03-18

    For the users of the high-brightness radiation sources of free-electron lasers it is desirable to reduce the FEL pulse length to 10 fs and below for time-resolved pump and probe experiments. Although it can be achieved by conventional compression methods for the electron beam or the chirped FEL pulse, the technical realization is demanding. In this presentation we study the impact of longitudinal wakefields in the undulator and how their properties can be used to reduced the amplifying part of the bunch to the desired length. Methods of actively controlling the wakefields are presented.

  16. An Experimental Study of an FEL Oscillator with a Linear Taper

    SciTech Connect

    Benson, S.; Gubeli, J.; Neil, G.R.

    2001-01-01

    Motivated by the work of Saldin, Schneidmiller and Yurkov, we have measured the detuning curve widths, spectral characteristics, efficiency, and energy spread as a function of the taper for low and high Q resonators in the IR Demo FEL at Jefferson Lab. Both positive and negative tapers were used. Gain and frequency agreed reasonably well with the predictions of a single mode theory. The efficiency agreed reasonably well for a negative taper with a high Q resonator but disagreed for lower Q values due to the large slippage parameter and the non-ideal resonator Q. We saw better efficiency for a negative taper than for the same positive taper. The energy spread induced in the beam, normalized to the efficiency is larger for the positive taper than for the corresponding negative taper. This indicates that a negative taper is preferred over a positive taper in an energy recovery FEL.

  17. Design Studies for a High-Repetition-Rate FEL Facility at LBNL.

    SciTech Connect

    CORLETT, J.; BELKACEM, A.; BYRD, J. M.; FAWLEY, W.; KIRZ, J.; LIDIA, S.; MCCURDY, W.; PADMORE, H.; PENN, G.; POGORELOV, I.; QIANG, J.; ROBIN, D.; SANNIBALE, F.; SCHOENLEIN, R.; STAPLES, J.; STEIER, C.; VENTURINI, M.; WAN, W.; WILCOX, R.; ZHOLENTS, A.

    2007-10-04

    Lawrence Berkeley National Laboratory (LBNL) is working to address the needs of the primary scientific Grand Challenges now being considered by the U.S. Department of Energy, Office of Basic Energy Sciences: we are exploring scientific discovery opportunities, and new areas of science, to be unlocked with the use of advanced photon sources. A partnership of several divisions at LBNL is working to define the science and instruments needed in the future. To meet these needs, we propose a seeded, high-repetition-rate, free-electron laser (FEL) facility. Temporally and spatially coherent photon pulses, of controlled duration ranging from picosecond to sub-femtosecond, are within reach in the vacuum ultraviolet (VUV) to soft X-ray regime, and LBNL is developing critical accelerator physics and technologies toward this goal. We envision a facility with an array of FELs, each independently configurable and tunable, providing a range of photon-beam properties with high average and peak flux and brightness.

  18. Seeded FEL Microbunching Experiments at the UCLA Neptune Laboratory

    SciTech Connect

    Tochitsky, S. Ya.; Musumeci, P.; Rosenzweig, J. B.; Joshi, C.; Gottschalk, S. C.

    2010-11-04

    Seeded high-gain FELs, which can generate very powerful radiation pulses in a relatively compact undulator and simultaneously modulate the electron beam longitudinally at the seed wavelength, are important tools for advanced accelerator development. A single-pass 0.5-9 THz FEL amplifier-buncher driven by a regular photoinjector is being built at the UCLA Neptune Laboratory. FEL interactions at 340 {mu}m (1 THz) are considered for the first experiment, since time-resolved measurements of longitudinal current distribution of the bunched beam using the RF deflecting cavity are possible. A design of a 0.2-2.0 {mu}m FEL using the same undulators is presented. In this case the FEL is driven by a high-peak current beam from the laser-plasma accelerator tunable in the 100-300 MeV range.

  19. Simulations of the LANL regenerative amplifier FEL

    SciTech Connect

    Kesselring, M.; Colson, W.B.; Wong, R.K.; Sheffield, R.L.

    1997-08-01

    The LANL regenerative amplifier FEL is designed to produce an average output power of 1 kW. Simulations study the transverse effects due to guiding by the intense electron beam and feedback. These simulations coupled with experimental measurements can be used to improve future high-power FEL designs.

  20. Start-to-End Simulations of the LCLS Accelerator and FEL Performance at Very Low Charge

    SciTech Connect

    Ding, Y; Brachmann, A.; Decker, F.-J.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Loos, H.; Miahnahri, A.; Nuhn, H.-D.; Ratner, D.; Turner, J.; Welch, J.; White, W.; Wu, J.; Pellegrini, C.; /UCLA

    2009-05-26

    The Linac Coherent Light Source (LCLS) is an x-ray Free-electron Laser (FEL) being commissioned at Stanford Linear Accelerator Center (SLAC). Recent beam measurements have shown that, using the LCLS injector-linac-compressors, the beam emittance is very small at 20 pC. In this paper we perform start-to-end simulations of the entire accelerator including the FEL undulator and study the FEL performance versus the bunch charge. At 20 pC charge, these calculations associated with the measured beam parameters suggest the possibility of generating a longitudinally coherent single x-ray spike with 2-femtosecond (fs) duration at a wavelength of 1.5 nm. At 100 pC charge level, our simulations show an x-ray pulse with 10 femtosecond duration and up to 10{sup 12} photons at a wavelength of 1.5 {angstrom}. These results open exciting possibilities for ultrafast science and single shot molecular imaging.

  1. ECEAP 1991 Longitudinal Study and Annual Report.

    ERIC Educational Resources Information Center

    Washington State Office of Community Development, Olympia.

    Washington State's Early Childhood Education and Assistance Program (ECEAP) provides a comprehensive, family-focused preschool program designed to help low-income children succeed in the public school system and help families support and participate in their children's success. Findings from an ongoing longitudinal study of the ECEAP program…

  2. MPCP Longitudinal Educational Growth Study Baseline Report

    ERIC Educational Resources Information Center

    Witte, John F.; Wolf, Patrick J.; Cowen, Joshua M.; Fleming, David J.; Lucas-McLean, Juanita

    2008-01-01

    This report focuses on the initial design, implementation and baseline results of the five-year Longitudinal Educational Growth Study (LEGS) of the Milwaukee Parental Choice Program (MPCP) being conducted by the School Choice Demonstration Project (SCDP). The LEGS will be the first evaluation of the participant effects of the MPCP using…

  3. Collaborative Knowledge-Building: A Longitudinal Study

    ERIC Educational Resources Information Center

    Li, Qing

    2009-01-01

    The focus of this paper is on knowledge-building in a technology-supported learning environment in higher education through a longitudinal study of a graduate course from 2003 to 2007. The primary question is: how do learning conditions designed into a graduate course contribute to collaborative knowledge building? In particular, two major…

  4. 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.

  5. Temporal and spectral evolution of a storage ring FEL source: Experimental results on Super-ACO and new theoretical approach

    SciTech Connect

    Hara, T.; Couprie, M.E. ||

    1995-12-31

    The Super-ACO FEL source in UV is now used for applications like a time-resolved fluorescence in biology and two colors experiments coupling FEL and Synchrotron Radiation, which are naturally synchronized. The stability of the FEL is then a critical issue for the users. Detailed experimental studies conducted on the temporal characteristics of the laser micropulse showed various phenomena, such as a longitudinal micropulse jitter and a deformation of a longitudinal micropulse distribution. A similar analysis has been performed on the laser spectral evolution with a scanning Fabry-Perot interferometer, showing a spectrum narrowing, and a wavelength drift. A longitudinal feedback system developed after the first user experiment, allowed to reduce significantly the longitudinal jitter, the intensity fluctuation and the spectral drift. Nevertheless, the stability of the FEL is very dependent on any perturbation, and the observed phenomena can not be described by former models like super-mode assuming a stationary regime. A new theoretical model has then been developed, in order to simulate dynamic behaviors. A simple iterative method is employed to obtain the laser spectrum. The access to the temporal distribution requires additional complexity, because the Fourier transformation has to be performed for each pass. The comparison between the experimental data and the simulation results will be given.

  6. Microbunching and Beam Break Up in DUV FEL Accelerator

    SciTech Connect

    Shaftan, T.; Carr, L.; Loos, H.; Sheehy, B.; Graves, William S.; Huang, Z.; Limborg, C.G.; /Brookhaven /MIT /SLAC

    2008-03-17

    We present the results of electron beam longitudinal modulation studies in the DUV-FEL accelerator. For bunch length determination we used the 'zero-phasing' method, based on a measurement of the chirped electron bunch energy spectra. The measurements revealed a spiky structure in the longitudinal phase space [1]. A model based on space charge effect is considered [2] to explain of the obtained phenomena. The analysis of the energy spectra has shown a sensitivity of the structure to the electron beam peak current, energy and longitudinal non-uniformity of the RF gun drive laser. Analytical calculations have demonstrated a qualitative agreement with experimental observations. Several experiments have been made to compare with theory; measured results are reviewed in this paper. The obtained effect is briefly discussed in relation to high brightness accelerators.

  7. FULL ELECTROMAGNETIC FEL SIMULATION VIA THE LORENTZ-BOOSTED FRAME TRANSFORMATION

    SciTech Connect

    Fawley, William; Vay, Jean-Luc

    2010-08-16

    Numerical electromagnetic simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz-boosted frame. A particularly good application for calculation in a boosted frame isthat of short wavelength free-electron lasers (FELs) where a high energy electron beam with small fractional energy spread interacts with a static magnetic undulator. In the optimal boost frame (i.e., the ponderomotive rest frame), the red-shifted FEL radiation and blue-shifted undulator field have identical wavelengths and the number of required longitudinal grid cells and time-steps for fully electromagnetic simulation (relative to the laboratory frame) decrease by factors of gamma^2 each. In theory, boosted frame EM codes permit direct study of FEL problems for which the eikonal approximation for propagation of the radiation field and wiggler-period-averaging for the particle-field interaction may be suspect. We have adapted the WARP code to apply this method to several electromagnetic FEL problems including spontaneous emission, strong exponential gain in a seeded, single pass amplifier configuration, and emission from e-beams in undulators with multiple harmonic components. WARP has a standard relativistic macroparticle mover and a fully 3-D electromagnetic field solver. We discuss our boosted frame results and compare with those obtained using the ?standard? eikonal FEL simulation approach.

  8. What Can We Learn From Longitudinal Studies of Adult Development?

    PubMed Central

    Schaie, K. Warner

    2005-01-01

    This article distinguishes between normal and pathological aging, provides an interdisciplinary context, and then considers a sample case of cognitive aging. Developmental influences on cognition include the physiological infrastructure, genetic predispositions, and environmental influences. Different types of longitudinal studies are distinguished, and contrasting findings of cross-sectional and longitudinal are examined in the sample case of the Seattle Longitudinal Study. Also considered is the longitudinal context for intervention studies and the role of longitudinal family studies in assessing rate of aging and generational differences in rates of aging. Finally, attention is given to the role of longitudinal studies in the early detection of risk for dementia in advanced age. PMID:16467912

  9. The Canadian longitudinal study on aging (CLSA).

    PubMed

    Raina, Parminder S; Wolfson, Christina; Kirkland, Susan A; Griffith, Lauren E; Oremus, Mark; Patterson, Christopher; Tuokko, Holly; Penning, Margaret; Balion, Cynthia M; Hogan, David; Wister, Andrew; Payette, Hélène; Shannon, Harry; Brazil, Kevin

    2009-09-01

    ABSTRACTCanadians are living longer, and older persons are making up a larger share of the population (14% in 2006, projected to rise to 20% by 2021). The Canadian Longitudinal Study on Aging (CLSA) is a national longitudinal study of adult development and aging that will recruit 50,000 Canadians aged 45 to 85 years of age and follow them for at least 20 years. All participants will provide a common set of information concerning many aspects of health and aging, and 30,000 will undergo an additional in-depth examination coupled with the donation of biological specimens (blood and urine). The CLSA will become a rich data source for the study of the complex interrelationship among the biological, physical, psychosocial, and societal factors that affect healthy aging. PMID:19860977

  10. Aging in Rett syndrome: a longitudinal study.

    PubMed

    Halbach, N S J; Smeets, E E J; Steinbusch, C; Maaskant, M A; van Waardenburg, D; Curfs, L M G

    2013-09-01

    Little is known about the aging process of people with specific syndromes, like Rett syndrome (RTT). Recognition of the clinical and behavioral characteristics of the adult RTT is needed in order to improve future management of the RTT girl and counseling of parents. In association with the Dutch RTT parent association, a 5-year longitudinal study was carried out. The study population consisted of 53 adult women with a clinical diagnosis of RTT. Postal questionnaires were sent, including demographic features, skills, physical and psychiatric morbidity. At the time of the second measurement seven women had died. In 2012, 80% of the questionnaires (37/46) were returned. Mean age of the women was 31.4 years. Molecular confirmation was possible for 83% of the women for whom analyses were carried out. The adult RTT woman has a more or less stable condition. The general disorder profile is that of a slow on-going deterioration of gross motor functioning in contrast to a better preserved cognitive functioning, less autonomic and epileptic features and good general health. This is the first longitudinal cohort study about aging in RTT. Continuing longitudinal studies are needed to gain more insight into the aging process in RTT. PMID:23167724

  11. Using the Longitudinal Study as a Central Teaching Focus.

    ERIC Educational Resources Information Center

    Demchik, Michael J.

    1999-01-01

    Argues that treatment of one investigative longitudinal topic from start to finish in a high school biology class can illustrate many major ideas and concepts. Discusses ways to use various longitudinal studies of plant growth with General Biology classes. (WRM)

  12. Design study of the bending sections between harmonic cascade FEL stages

    SciTech Connect

    Wan, Weishi; Corlett, John; Fawley, William; Zholents, A.

    2004-06-30

    The present design of LUX (linac based ultra-fast X-ray facility) includes a harmonic cascade FEL chain to generate coherent EUV and soft X-ray radiation. Four cascade stages, each consisting of two undulators acting as a modulator and a radiator, respectively, are envisioned to produce photons of approximate wavelengths 48 nm, 12 nm, 4 nm and 1 nm. Bending sections may be placed between the modulator and the radiator of each stage to adjust and maintain bunching of the electrons, to separate, in space, photons of different wavelengths and to optimize the use of real estate. In this note, the conceptual design of such a bending section, which may be used at all four stages, is presented. Preliminary tracking results show that it is possible to maintain bunch structure of nm length scale in the presence of errors, provided that there is adequate orbit correction and there are 2 families of trim quads and trim skew quads, respectively, in each bending section.

  13. Multidimensional simulation studies of the SELENE FEL oscillator/buncher followed by a radiator/amplifier output scheme

    SciTech Connect

    Hahn, S.J.; Fawley, W.M.

    1995-02-01

    We analyze and present numerical simulations of the so-called electron output scheme [G. I. Erg et al., 15th Int. FEL Conf., The Hague, The Netherlands, 1993, Book of Abstracts p. 50; Preprint Budker INP 93-75] applied to the SELENE proposal of using a high power FEL to illuminate satellite solar cells. In this scheme, a first stage FEL oscillator bunches the electron beam while a second stage ``radiator`` extracts high power radiation. Our analysis suggests only in the case where the radiator employs a long, tapered undulator will the electron output scheme produce a significant increase in extraction efficiency over what is obtainable from a simple, single-stage oscillator. 1- and 2-D numerical simulations of a 1.7{mu}m FEL employing the electron output scheme show reasonably large bunching fractions ({approximately} 0.3--0.4) at the output of the oscillator stage but only {le}2% extraction efficiency from the radiator stage.

  14. Cohort Profile: Wisconsin longitudinal study (WLS)

    PubMed Central

    Herd, Pamela; Carr, Deborah; Roan, Carol

    2014-01-01

    The Wisconsin Longitudinal Study (WLS) is a longitudinal study of men and women who graduated from Wisconsin high schools in 1957 and one of their randomly selected siblings. Wisconsin is located in the upper midwest of the United States and had a population of approximately 14 000 000 in 1957, making it the 14th most populous state at that time. Data spanning almost 60 years allow researchers to link family background, adolescent characteristics, educational experiences, employment experiences, income, wealth, family formation and social and religious engagement to midlife and late-life physical health, mental health, psychological well-being, cognition, end of life planning and mortality. The WLS is one of the few longitudinal data sets that include an administrative measure of cognition from childhood. Further, recently collected saliva samples allow researchers to explore the inter-relationships among genes, behaviours and environment, including genetic determinants of behaviours (e.g. educational attainment); the interactions between genes and environment; and how these interactions predict behaviours. Most panel members were born in 1939, and the sample is broadly representative of White, non-Hispanic American men and women who have completed at least a high school education. Siblings cover several adjoining cohorts: they were born primarily between 1930 and 1948. At each interview, about two-thirds of the sample lived in Wisconsin, and about one-third lived elsewhere in the United States or abroad. The data, along with documentation, are publicly accessible and can be accessed at http://www.ssc.wisc.edu/wlsresearch/. Requests for protected data or assistance should be sent to wls@ssc.wisc.edu. PMID:24585852

  15. Colorado longitudinal twin study of reading disability.

    PubMed

    Wadsworth, Sally J; DeFries, John C; Olson, Richard K; Willcutt, Erik G

    2007-12-01

    The primary objectives of the present study are to introduce the Colorado Longitudinal Twin Study of Reading Disability, the first longitudinal twin study in which subjects have been specifically selected for having a history of reading difficulties, and to present some initial assessments of the stability of reading performance and cognitive abilities in this sample. Preliminary examination of the test scores of 124 twins with a history of reading difficulties and 154 twins with no history of reading difficulties indicates that over the 5- to 6-year interval between assessments, cognitive and reading performance are highly stable. As a group, those subjects with a history of reading difficulties had substantial deficits relative to control subjects on all measures at initial assessment, and significant deficits remained at follow-up. The stability noted for all cognitive and achievement measures was highest for a composite measure of reading, whose average stability correlation across groups was 0.80. Results of preliminary behavior genetic analyses for this measure indicated that shared genetic influences accounted for 86% and 49% of the phenotypic correlations between the two assessments for twin pairs with and without reading difficulties, respectively. In addition, genetic correlations reached unity for both groups, suggesting that the same genetic influences are manifested at both time points. PMID:18060583

  16. SASE FEL Polarization Control Using Crossed Undulator

    SciTech Connect

    Ding, Yuantao; Huang, Zhirong; /SLAC

    2008-09-30

    There is a growing interest in producing intense, coherent x-ray radiation with an adjustable and arbitrary polarization state. In this paper, we study the crossed undulator scheme for rapid polarization control in a self-amplified spontaneous emission (SASE) free electron laser (FEL). Because a SASE source is a temporally chaotic light, we perform a statistical analysis on the state of polarization using FEL theory and simulations. We show that by adding a small phase shifter and a short (about 1.3 times the FEL power gain length), 90{sup o} rotated planar undulator after the main SASE planar undulator, one can obtain circularly polarized light--with over 80% polarization--near the FEL saturation.

  17. The BESSY FEL project

    NASA Astrophysics Data System (ADS)

    Abo-Bakr, M.; Anders, W.; Bahrdt, J.; Bakker, R. J.; Eberhardt, W.; Faatz, B.; Follath, R.; Gaupp, A.; von Hartrott, M.; Jaeschke, E.; Krämer, D.; Kuske, P.; Martin, M.; Müller, R.; Prange, H.; Reiche, S.; Sandner, W.; Senf, F.; Will, I.; Wüstefeld, G.

    2002-05-01

    Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY) plans to construct a linac-based single-pass FEL as an addition to its existing third generation storage-ring-based light-source. The project aims to obtain an FEL-based user-facility that covers the VUV and soft X-ray spectral range (20 eV⩽ℏ ω⩽1 keV). At present, the design stage is funded as a collaboration between BESSY, DESY, the Hahn-Meitner-Institute in Berlin, and the Max-Born-Institute in Berlin. This stage focuses on optimization of the FEL as a user light-source, both with respect to its capabilities and in its performance. Important issues are: stability, seeding options of the SASE FEL, wavelength-tunability, synchronization with external laser sources and, on a longer time-scale, the generation of ultra-short (<20 fs RMS) optical pulses.

  18. Ther FERMI FEL project at TRIESTE

    SciTech Connect

    Walker, R.P.; Bulfone, D.; Cargnello, F.

    1995-12-31

    The goal of the FERMI project - Free Electron Radiation and Matching Instrumentation - is to construct a new user facility for FEL radiation beams covering a broad spectral range (2-250 {mu}m) to complement the high brightness VUV/Soft-Xray radiation available from the ELETTRA synchrotron radiation facility at Trieste. A unique feature of the project will be the possibility of carrying out {open_quote}pump-probe{close_quote} experiments using synchronized radiation beams from FERMI and ELETTRA on the same sample. The project was launched at a meeting with Italian FEL experts held in Trieste on the 18th November 1994, chaired by C. Rubbia, as a collaboration between Sincrotrone Trieste, ENEA (Frascati), INFN (Frascati) and the University of Naples (Department of Electronic Engineering). The facility will make use of an existing linac, that forms part of the ELETTRA injection system, and a hall into which the beam can be extracted. In addition, for the first phase of the project equipment will be used from the suspended INFN/ENEA {open_quote}SURF{close_quote} FEL experiment, including the undulator, beam transport magnets and optical cavity. In this first International FEL Conference report on the project, we summarize the main features of the project, concentrating in particular on the most recent activities, including: results of measurements of the linac beam in the FEL mode of operation, further studies of the electron beam transport system including possibilities for bunch length manipulations, and further numerical calculations of the FEL performance.

  19. Technological Challenges to X-Ray FELs

    SciTech Connect

    Nuhn, Heinz-Dieter

    1999-09-16

    There is strong interest in the development of x-ray free electron lasers (x-ray FELs). The interest is driven by the scientific opportunities provided by intense, coherent x-rays. An x-ray FEL has all the characteristics of a fourth-generation source: brightness several orders of magnitude greater than presently achieved in third-generation sources, full transverse coherence, and sub-picosecond long pulses. The SLAC and DESY laboratories have presented detailed design studies for X-Ray FEL user facilities around the 0.1 nm wavelength-regime (LCLS at SLAC, TESLA X-Ray FEL at DESY). Both laboratories are engaged in proof-of-principle experiments are longer wavelengths (TTF FEL Phase I at 71 nm, VISA at 600-800 nm) with results expected in 1999. The technologies needed to achieve the proposed performances are those of bright electron sources, of acceleration systems capable of preserving the brightness of the source, and of undulators capable of meeting the magnetic and mechanical tolerances that are required for operation in the SASE mode. This paper discusses the technological challenges presented by the X-Ray FEL projects.

  20. Technological challenges to X-ray FELs

    NASA Astrophysics Data System (ADS)

    Nuhn, Heinz-Dieter

    2000-05-01

    There is strong interest in the development of X-ray Free Electron Lasers (X-ray FELs). The interest is driven by the scientific opportunities provided by intense, coherent X-rays. An X-ray FEL has all the characteristics of a fourth-generation source: brightness several orders of magnitude greater than presently achieved in third-generation sources, full transverse coherence, and sub-picosecond long pulses. The SLAC and DESY laboratories have presented detailed design studies for X-ray FEL user-facilities around the 0.1 nm wavelength regime (LCLS at SLAC, TESLA X-ray FEL at DESY). Both laboratories are engaged in proof-of-principle experiments at longer wavelengths (TTF FEL Phase I at 71 nm, VISA at 600-800 nm) with results expected in 1999. The technologies needed to achieve the proposed performances are those of bright electron sources, of acceleration systems capable of preserving the brightness of the source, and of undulators capable of meeting the magnetic and mechanical tolerances that are required for operation in the SASE mode. This paper discusses the technological challenges presented by the X-ray FEL projects.

  1. Psychosocial adjustment to ALS: a longitudinal study

    PubMed Central

    Matuz, Tamara; Birbaumer, Niels; Hautzinger, Martin; Kübler, Andrea

    2015-01-01

    For the current study the Lazarian stress-coping theory and the appendant model of psychosocial adjustment to chronic illness and disabilities (Pakenham, 1999) has shaped the foundation for identifying determinants of adjustment to ALS. We aimed to investigate the evolution of psychosocial adjustment to ALS and to determine its long-term predictors. A longitudinal study design with four measurement time points was therefore, used to assess patients' quality of life, depression, and stress-coping model related aspects, such as illness characteristics, social support, cognitive appraisals, and coping strategies during a period of 2 years. Regression analyses revealed that 55% of the variance of severity of depressive symptoms and 47% of the variance in quality of life at T2 was accounted for by all the T1 predictor variables taken together. On the level of individual contributions, protective buffering, and appraisal of own coping potential accounted for a significant percentage in the variance in severity of depressive symptoms, whereas problem management coping strategies explained variance in quality of life scores. Illness characteristics at T2 did not explain any variance of both adjustment outcomes. Overall, the pattern of the longitudinal results indicated stable depressive symptoms and quality of life indices reflecting a successful adjustment to the disease across four measurement time points during a period of about two years. Empirical evidence is provided for the predictive value of social support, cognitive appraisals, and coping strategies, but not illness parameters such as severity and duration for adaptation to ALS. The current study contributes to a better conceptualization of adjustment, allowing us to provide evidence-based support beyond medical and physical intervention for people with ALS. PMID:26441696

  2. Optical Klystron Enhancement to SASE X-ray FELs

    SciTech Connect

    Ding, Yuantao; Emma, Paul; Huang, Zhirong; Kumar, Vinit

    2006-04-07

    The optical klystron enhancement to self-amplified spontaneous emission (SASE) free electron lasers (FELs) is studied in theory and in simulations. In contrast to a seeded FEL, the optical klystron gain in a SASE FEL is not sensitive to any phase mismatch between the radiation and the microbunched electron beam. The FEL performance with the addition of four optical klystrons located at the undulator long breaks in the Linac Coherent Light Source (LCLS) shows significant improvement if the uncorrelated energy spread at the undulator entrance can be controlled to a very small level. In addition, FEL saturation at shorter x-ray wavelengths (around 1.0 A) within the LCLS undulator length becomes possible. We also discuss the application of the optical klystron in a compact x-ray FEL design that employs relatively low electron beam energy together with a shorter-period undulator.

  3. Paediatric UK demyelinating disease longitudinal study (PUDDLS)

    PubMed Central

    2011-01-01

    Background There is evidence that at least 5% of Multiple sclerosis (MS) cases manifest in childhood. Children with MS present with a demyelinating episode involving single or multiple symptoms prior to developing a second event (usually within two years) to then meet criteria for diagnosis. There is evidence from adult cohorts that the incidence and sex ratios of MS are changing and that children of immigrants have a higher risk for developing MS. A paediatric population should reflect the vanguard of such changes and may reflect trends yet to be observed in adult cohorts. Studying a paediatric population from the first demyelinating event will allow us to test these hypotheses, and may offer further valuable insights into the genetic and environmental interactions in the pathogenesis of MS. Methods/Design The Paediatric UK Demyelinating Disease Longitudinal Study (PUDDLS) is a prospective longitudinal observational study which aims to determine the natural history, predictors and outcomes of childhood CNS inflammatory demyelinating diseases. PUDDLS will involve centres in the UK, and will establish a cohort of children affected with a first CNS inflammatory demyelinating event for long-term follow up by recruiting for approximately 5 years. PUDDLS will also establish a biological sample archive (CSF, serum, and DNA), allowing future hypothesis driven research. For example, the future discovery of a biomarker will allow validation within this dataset for the evaluation of novel biomarkers. Patients will also be requested to consent to be contacted in the future. A secondary aim is to collaborate internationally with the International Paediatric Multiple Sclerosis Study Group when future collaborative studies are proposed, whilst sharing a minimal anonymised dataset. PUDDLS is the second of two jointly funded studies. The first (UCID-SS) is an epidemiological surveillance study that already received ethical approvals, and started on the 1st September 2009. There is

  4. Objectives, Design, and History of the National Longitudinal Study.

    ERIC Educational Resources Information Center

    Davis, J. A.; Collins, Elmer

    The National Longitudinal Study of the High School Class of 1972 (NLS) is a federally supported longitudinal study of a national sample of some 23,000 young people first surveyed as high school seniors in the spring of 1972. The historical precedents of such a study include the work of Friend and Haggert in a Boston settlement house, Louis…

  5. FEL phased array configurations

    NASA Astrophysics Data System (ADS)

    Shellan, Jeffrey B.

    1986-01-01

    The advantages and disadvantages of various phased array and shared aperture concepts for FEL configurations are discussed. Consideration is given to the characteristics of intra- and inter-micropulse phasing; intra-macropulse phasing; an internal coupled resonator configuration; and an injection locked oscillator array. The use of a master oscillator power amplifier (MOPA) configuration with multiple or single master oscillators for FELs is examined. The venetian blind, rotating plate, single grating, and grating rhomb shared aperture concepts are analyzed. It is noted that the shared aperture approach using a grating rhomb and the MOPA concept with a single master oscillator and a coupled resonator are useful for FEL phased array configurations; and the MOPA concept is most applicable.

  6. Early Predictors of Adolescent Depression: A 7-Year Longitudinal Study

    ERIC Educational Resources Information Center

    Mazza, James J.; Abbott, Robert D.; Fleming, Charles B.; Harachi, Tracy W.; Cortes, Rebecca C.; Park, Jisuk; Haggerty, Kevin P.; Catalano, Richard F.

    2009-01-01

    This study examined the longitudinal relationship of early elementary predictors to adolescent depression 7 years later. The sample consisted of 938 students who have been part of a larger longitudinal study that started in 1993. Data collected from parents, teachers, and youth self-reports on early risk factors when students were in 1st and 2nd…

  7. Beyond Terman: Contemporary Longitudinal Studies of Giftedness and Talent.

    ERIC Educational Resources Information Center

    Subotnik, Rena F., Ed.; Arnold, Karen D., Ed.

    This volume presents 16 papers describing recent longitudinal studies of giftedness. Papers have the following titles and authors: (1) "Longitudinal Study of Giftedness and Talent" (Rena F. Subotnik and Karen D. Arnold); (2) "The Illinois Valedictorian Project: Early Adult Careers of Academically Talented Male High School Students" (Karen D.…

  8. Performance of the KHI FEL device at FEL-SUT

    NASA Astrophysics Data System (ADS)

    Yokoyama, M.; Oda, F.; Nomaru, K.; Koike, H.; Sobajima, M.; Miura, H.; Kawai, M.; Kuroda, H.

    2002-05-01

    FEL lasing with the saturated power in the wavelength of 4-16 μm was achieved by using the KHI (Kawasaki Heavy Industries, Ltd.) FEL device. The macro-pulse length of the electron beam was improved by using the LaB 6 cathode instead of the dispenser cathode as a cathode of the OCS RF-gun. The improvement yielded the saturated FEL power with the macro-pulse length of 0.5-1.5 μs. The FEL energy was 2-40 mJ. The measured FEL output powers were in agreement with the values which were taken into account Piovella's theory.

  9. NASA Planetary Science Summer School: Longitudinal Study

    NASA Astrophysics Data System (ADS)

    Giron, Jennie M.; Sohus, A.

    2006-12-01

    NASA’s Planetary Science Summer School is a program designed to prepare the next generation of scientists and engineers to participate in future missions of solar system exploration. The opportunity is advertised to science and engineering post-doctoral and graduate students with a strong interest in careers in planetary exploration. Preference is given to U.S. citizens. The “school” consists of a one-week intensive team exercise learning the process of developing a robotic mission concept into reality through concurrent engineering, working with JPL’s Advanced Project Design Team (Team X). This program benefits the students by providing them with skills, knowledge and the experience of collaborating with a concept mission design. A longitudinal study was conducted to assess the impact of the program on the past participants of the program. Data collected included their current contact information, if they are currently part of the planetary exploration community, if participation in the program contributed to any career choices, if the program benefited their career paths, etc. Approximately 37% of 250 past participants responded to the online survey. Of these, 83% indicated that they are actively involved in planetary exploration or aerospace in general; 78% said they had been able to apply what they learned in the program to their current job or professional career; 100% said they would recommend this program to a colleague.

  10. Users program for storage-ring based FEL and synchrotron sources of the Duke FEL Laboratory

    SciTech Connect

    Straub, K.D.; Barnett, G.; Burnham, B.

    1995-12-31

    The storage ring at the Duke FEL Laboratory was first operated with a stored e-beam in November, 1994. It has now achieved operation energies in excess 1 GeV with more than 100 mA current at 280 MeV. The ring has several ports for FEL and synchrotron light source research. The circulating ring current can be synchronized with the seperate Mark III FEL operating in the 2-9.5 {mu}m IR region. This allows low optical jitter (10-20 ps) between the two sources and thus pump-probe operation. The ring has been configured to drive a number of light sources including the OK-4 FEL system capable of FEL operation between 400 and 65 nm, an inverse Compton scattering source using this undulator which will yield 4-200 MeV gammas, an undulator source at approximately 40 {angstrom} (not an FEL), a mm FEL with inverse compton scattering providing 1-100 keV x-rays and two synchrotron ports from the bend magnets for which the {lambda}{sub c} = 11-12 {angstrom} for 1 GeV. The broadly tunable FEL sources and their associated inverse compton scattering are extremely bright. The initial research proposals, submitted to the Laboratory emphasizes photoelectron spectroscopy, PEEM, high resolution vacuum UV of gases, solid spectroscopy and photochemistry in the UV, X-ray microprobe studies, X-ray microscopy, X-ray holography, X-ray crystallography, Mossbauer spectroscopy, nuclear spectroscopy, neutron production, photon activation therapy and broadband synchrotron as a probe of fast reaction in the IR and near IR.

  11. Advanced studies at the VISA FEL in the SASE and seeded modes

    NASA Astrophysics Data System (ADS)

    Andonian, G.; Dunning, M.; Hemsing, E.; Murokh, A.; Pellegrini, C.; Reiche, S.; Rosenzweig, J.; Babzien, M.; Yakimenko, V.

    2008-08-01

    The VISA (Visible to Infrared SASE Amplifier) program has been in operation at the BNL ATF since the year 2000. The program has produced numerous results including, demonstrated saturation at 840 nm with a gain length of 18 cm, chirped beam amplification with the observation of anomalously large bandwidth of the emitted radiation, and successful benchmarking of a start-to-end simulation suite to measured results. This paper will review the prior results of the VISA program and discuss planned novel measurements, including detuning studies of a 1 μm seeded amplifier, and measurements of the orbital angular momentum of the emitted radiation. The installation of a dedicated chicane bunch compressor followed by an x-band linac to mitigate energy spread will allow for high-current operations (reduced saturation length, and deep-saturation studies). Other measurements, such as coherent transition undulator radiation, are also proposed.

  12. Chirped pulse amplification at VISA-FEL

    NASA Astrophysics Data System (ADS)

    Agustsson, R.; Andonian, G.; Babzien, M.; Ben-Zvi, I.; Frigola, P.; Huang, J.; Murokh, A.; Palumbo, L.; Pellegrini, C.; Reiche, S.; Rosenzweig, J.; Travish, G.; Vicario, C.; Yakimenko, V.

    2004-08-01

    Chirped beam manipulations are of the great interest to the free electron laser (FEL) community as potential means of obtaining ultra short X-ray pulses. The experiment is under way at the accelerator test facility (ATF) at Brookhaven National Laboratory (BNL) to study the FEL process limits with the under-compressed chirped electron beam. High gain near-saturation SASE operation was achieved with the strongly chirped beam (˜2.8% head-to-tail). The measured beam dynamics and SASE properties are presented, as well as the design parameters for the next round of experiment utilizing the newly installed UCLA/ATF chicane compressor.

  13. Diagnostic technique applied for FEL electron bunches

    NASA Astrophysics Data System (ADS)

    Brovko, O.; Grebentsov, A.; Morozov, N.; Syresin, E.; Yurkov, M.

    2016-05-01

    Diagnostic technique applied for FEL ultrashort electron bunches is developed at JINR-DESY collaboration within the framework of the FLASH and XFEL projects. Photon diagnostics are based on calorimetric measurements and detection of undulator radiation. The infrared undulator constructed at JINR and installed at FLASH is used for longitudinal bunch shape measurements and for two-color lasing provided by the FIR and VUV undulators. The pump probe experiments with VUV and FIR undulators provide the bunch profile measurements with resolution of several femtosecond. The new three microchannel plates (MCP) detectors operated in X-ray range are under development now in JINR for SASE1-SASE 3 European XFEL.

  14. Feedback Requirements for SASE-FELs

    SciTech Connect

    Loos, Henrik; /SLAC

    2012-07-06

    The operation of a Self Amplified Spontaneous Emission (SASE) Free Electron Lasers (FEL) at soft and hard X-ray wavelengths driven by a high brightness electron beam imposes strong requirements on the stability of the accelerator and feedback systems are necessary to both guarantee saturation of the SASE process as well as a stable photon beam for user experiments. Diagnostics for the relevant transverse and longitudinal beam parameters are presented and various examples of feedback systems for bunches with low repetition rate as well as systems for intra bunch train feedbacks are discussed.

  15. Diagnostics for the CEBAF FEL Injector

    NASA Astrophysics Data System (ADS)

    Kehne, D.; Engwall, D.; Jordan, K.; Benson, S.; Bohn, C.; Cardman, L.; Douglas, D.; Happek, U.; Krafft, G. A.; Neil, G.; Sinclair, C.

    1996-04-01

    A test stand for the 10 MeV, 5 mA average current injector for the CEBAF FEL is currently under construction. The injector tests will progress through two phases. The first phase will be devoted to characterizing the gun transverse and longitudinal emittance performance as a function of bunch charge, beam size, and energy. The goal of the second phase is to achieve the nominal requirements of the 10 MeV injector, including bunch length, emittance, charge per bunch, and energy stability. This paper summarizes the diagnostics planned to be used in these experiments.

  16. A proposed visible FEL Facility at Boeing

    SciTech Connect

    Dowell, D.H.; Adamski, J.L.; Hayward, T.D.

    1995-12-31

    A 1-kW average power, visible wavelength FEL is described, based on a 120-MeV, 0.1. A macropulse average current linac operating at a duty factor of 0. 6% and having average beam power of 70 kW. The accelerator will employ a demonstrated photoinjector, 18-MeV, 433-MHz linac as an injector, followed by a 1300-MHz longitudinal phase space {open_quotes} linearizer,{close_quotes} a magnetic buncher chicane, and seven 1300-MHz, pulsed traveling wave linac sections. The magnets used to transport the beam from the linac to the FEL centerline, the 5-m THUNDER wiggler, and the optical resonator will be reclaimed from previous FEL demonstration experiments. We expect to attain pulse lengths of 7 ps for 3.5 nC, with minimal distortion of the pulse profile and normalized rms emittance of 7.5 {+-} 2.5 {pi} mm-mr. FELEX projects a laser conversion efficiency of 4.3 %, yielding average output of 3 kW.

  17. FEL-accelerator related diagnostics

    SciTech Connect

    Kevin Jordan; David Douglas; Stephen V. Benson; Pavel Evtuschenko

    2007-08-02

    Free Electron Lasers (FEL) present a unique set of beam parameters to the diagnostics suite. The FEL requires characterization of the full six dimensional phase space of the electron beam at the wiggler and accurate alignment of the electron beam to the optical mode of the laser. In addition to the FEL requirements on the diagnostics suite, the Jefferson Lab FEL is operated as an Energy Recovered Linac (ERL) which imposes additional requirements on the diagnostics. The ERL aspect of the Jefferson Lab FEL requires that diagnostics operate over a unique dynamic range and operate with simultaneous transport of the accelerated and energy recovered beams. This talk will present how these challenges are addressed at the Jefferson Lab FEL.

  18. The VISA FEL undulator

    SciTech Connect

    Carr, R.; Cornacchia, M.; Emma, P.

    1998-08-01

    The Visible-Infrared SASE Amplifier (VISA) FEL is an experimental device designed to show Self Amplified Spontaneous Emission (SASE) to saturation in the visible light energy range. It will generate a resonant wavelength output from 800--600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is the first SASE FEL designed to reach saturation, and its diagnostics will provide important checks of theory. This paper includes a description of the VISA undulator, the magnet measuring and shimming system, and the alignment strategy. VISA will have a 4 m pure permanent magnet undulator comprising four 99 cm segments, each with 55 periods of 18 mm length. The undulator has distributed focusing built into it, to reduce the average beta function of the 70--85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walkoff, or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, the authors expect to be able to control trajectory walkoff to less than {+-}50 {micro}m per field gain length.

  19. THE VISA FEL UNDULATOR

    SciTech Connect

    CARR,R.; CORNACCHIA,M.; EMMA,P.; NUHN,H.D.; FULAND,R.; JOHNSON,E.; RAKOWSKY,G.; LIDIA,S.; BERTOLINI,L.; LIBKIND,M.; FRIGOLA,P.; PELLEGRINI,C.; ROSENZWEIG,J.

    1998-08-16

    The Visible-Infrared SASE Amplifier (VISA) FEL is an experimental device designed to show Self Amplified Spontaneous Emission (SASE) to saturation in the visible light energy range. It will generate a resonant wavelength output from 800--600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is the first SASE FEL designed to reach saturation, and its diagnostics will provide important checks of theory. This paper includes a description of the VISA undulator, the magnet measuring and shimming system, and the alignment strategy. VISA will have a 4 m pure permanent magnet undulator comprising four 99 cm segments, each with 55 periods of 18 mm length. The undulator has distributed focusing built into it, to reduce the average beta function of the 70--85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walkoff or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, the authors expect to be able to control trajectory walkoff to less than {+-}50 pm per field gain length.

  20. Tapered undulators for SASE FELs

    NASA Astrophysics Data System (ADS)

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2002-05-01

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission, where the radiation tends to have a relatively broad bandwidth and limited temporal coherence. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of tapered undulators for parameters corresponding to the Argonne low-energy undulator test line FEL and the proposed linac coherent light source.

  1. Saturation and pulsed FEL dynamics

    SciTech Connect

    Giannessi, L.; Mezi, L.

    1995-12-31

    The behavior of a FEL operating in the saturated pulsed regime, may be reproduced by the linear FEL integral equation, suitably modified to include saturation effects through a gain depression coefficient depending on the laser intensity. This simple method allows to evaluate several FEL parameters like gain, efficiency, band-width and optical pulse duration as functions of the optical cavity length, only with a numerical integration. The predictions have been compared with available experimental and numerical data, and the method has been applied to estimate the operating characteristics of some planned FEL experiments.

  2. Innovative uses of X-ray FEL and the pulsed magnets: High magnetic field X-ray scattering studies on quantum materials

    NASA Astrophysics Data System (ADS)

    Jang, H.; Nojiri, H.; Gerber, S.; Lee, W.-S.; Zhu, D.; Lee, J.-S.; Kao, C.-C.

    X-ray scattering under high magnetic fields provides unique opportunities for solving many scientific puzzles in quantum materials, such as strongly correlated electron systems. Incorporating high magnetic field capability presents serious challenges at an x-ray facility, including the limitation on the maximum magnetic field even with a DC magnet (up to ~20 Tesla), expensive cost in development, radiation damage, and limited flexibility in the experimental configuration. These challenges are especially important when studying the symmetry broken state induced by the high magnetic field are necessary, for example, exploring intertwined orders between charge density wave (CDW) and high Tc superconductivity. Moreover, a gap in magnetic field strengths has led to many discrepancies and puzzling issues for understanding strongly correlated systems - is a CDW competing or more intimately intertwined with high-temperature superconductivity. To bridge this gap and resolve these experimental discrepancies, one needs an innovative experimental approach. Here, we will present a new approach to x-ray scattering under high magnetic field up to 28 Teals by taking advantage of brilliant x-ray free electron laser (FEL). The FEL generates sufficiently high photon flux for single shot x-ray scattering experiment. In this talk, we will also present the first demonstration about the field induced CDW order in YBCO Ortho-VIII with 28 Tesla, which show the totally unexpected three-dimensional behavior.

  3. Three-dimensional simulation of a hole-coupled FEL oscillator

    SciTech Connect

    Krishnagopal, S.; Xie, M.; Kim, K.J.; Sessler, A.

    1991-08-01

    The performance of a two-mirror resonator with holes for out-coupling has been examined in a previous study in which the FEL gain was neglected, but the geometrical effect of the wiggler aperture was included in the optical calculation. The phenomenon of mode degeneracy was found to occur, that has serious implications for the stability of performance when the FEL gain is included. We have developed a FEL oscillator code based on TDA'', a three-dimensional FEL amplifier code, to study the mode characteristics in the presence of an FEL. We find that the interaction of the radiation and the FEL has an important, and positive, impact on the mode-profile and related cavity performance parameters. In particular, mode degeneracy is not expected to be a serious problem for reasonable FEL oscillator designs. 8 refs., 4 figs., 1 tab.

  4. Simulation studies of a XUV/soft X-ray harmonic-cascade FEL for the proposed LBNL recirculating linac*

    SciTech Connect

    Fawley, W.M.; Barletta, W.A.; Corlett, J.N.; Zholents, A.

    2003-06-02

    Presently there is significant interest at LBNL in designing and building a facility for ultrafast (i.e. femtosecond time scale) x-ray science based upon a superconducting, recirculating RF linac (see Corlett et al. for more details). In addition to producing synchrotron radiation pulses in the 1-15 keV energy range, we are also considering adding one or more free-electron laser (FEL) beamlines using a harmonic cascade approach to produce coherent XUV soft X-ray emission beginning with a strong input seed at {approx}200 nm wavelength obtained from a ''conventional'' laser. Each cascade is composed of a radiator together with a modulator section, separated by a magnetic chicane. The chicane temporally delays the electron beam pulse in order that a ''virgin'' pulse region (with undegraded energy spread) be brought into synchronism with the radiation pulse, which together then undergo FEL action in the modulator. We present various results obtained with the GINGER simulation code examining final output sensitivity to initial electron beam parameters. We also discuss the effects of spontaneous emission and shot noise upon this particular cascade approach which can limit the final output coherence.

  5. Separation-Individuation of Late Adolescents : A Longitudinal Study

    ERIC Educational Resources Information Center

    Aslan, Sevda; Gelbal, Selahattin

    2016-01-01

    The aim of this study was to demonstrate the change in separation-individuation between late adolescents in the first, second, third and fourth year of higher education. The study sample used for this longitudinal study consisted of 148 students attending class studies, computer education and science education departments of Kirikkale University.…

  6. Baseline Report for the Korean-English Longitudinal Study.

    ERIC Educational Resources Information Center

    Kim, Kenneth Kong-On; Hong, Nam Sook

    The goals and methods of a longitudinal study of language development of eight Korean-English bilingual children are reported. The children were ages 4-8 at the beginning of the study. The goals of the study were (1) to document and analyze the development of English in natural communicative contexts, (2) to study the pattern of language shift…

  7. Short wavelength FELS

    SciTech Connect

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs.

  8. Electron Beam Diagnostics Of The JLAB UV FEL

    SciTech Connect

    Evtushenko, Pavel; Benson, Stephen; Biallas, George; Coleman, James; Dickover, Cody; Douglas, David; Marchlik, Matthew; Sexton, Daniel; Tennant, Christopher

    2011-03-01

    In this contribution we describe various systems and aspects of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line at the existing 10 kW IR Upgrade FEL. Here, we describe a set of the following systems. A combination of OTR and phosphor viewers is used for measurements of the transverse beam profile, transverse emittance, and Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A system of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurement system is used to set up bunch compression in an optimal way, such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of diagnostic systems made a significant contribution in achieving first lasing of the FEL after only about 60 hours of beam operation.

  9. Optimization of high average power FEL beam for EUV lithography

    NASA Astrophysics Data System (ADS)

    Endo, Akira

    2015-05-01

    Extreme Ultraviolet Lithography (EUVL) is entering into high volume manufacturing (HVM) stage, with high average power (250W) EUV source from laser produced plasma at 13.5nm. Semiconductor industry road map indicates a scaling of the source technology more than 1kW average power by high repetition rate FEL. This paper discusses on the lowest risk approach to construct a prototype based on superconducting linac and normal conducting undulator, to demonstrate a high average power 13.5nm FEL equipped with optimized optical components and solid state lasers, to study FEL application in EUV lithography.

  10. Social Class Differentiation in Cognitive Development: A Longitudinal Study.

    ERIC Educational Resources Information Center

    Golden, Mark; And Others

    In an effort to isolate the emergence and causes of social class differences in intellectual performance, this longitudinal study was undertaken as a follow-up on a cross-sectional study that yielded no social class differences on the Cattell Infant Intelligence Scale for 12-, 18-, and 24-month-old black children. In the present study, 89 children…

  11. A Longitudinal Study of Judge Leniency and Consistency.

    ERIC Educational Resources Information Center

    Lunz, Mary E.; O'Neill, Thomas R.

    This retrospective longitudinal study was designed to show grading leniency patterns of judges within and across clinical examination administrations. Data from 17 different administrations of the histology examination of the American Society of Clinical Pathologists over 10 years were studied. Over the 10 years there were 4,683 candidates and 57…

  12. Longitudinal Study of Low and High Achievers in Early Mathematics

    ERIC Educational Resources Information Center

    Navarro, Jose I.; Aguilar, Manuel; Marchena, Esperanza; Ruiz, Gonzalo; Menacho, Inmaculada; Van Luit, Johannes E. H.

    2012-01-01

    Background: Longitudinal studies allow us to identify, which specific maths skills are weak in young children, and whether there is a continuing weakness in these areas throughout their school years. Aims: This 2-year study investigated whether certain socio-demographic variables affect early mathematical competency in children aged 5-7 years.…

  13. Findings from longitudinal cohort studies: Gothenburg and Jerusalem.

    PubMed

    Stessman, J; Hammerman-Rozenberg, R; Svanborg, A

    1996-08-01

    The longitudinal study of age-homogeneous cohorts is a powerful tool to elucidate age-related changes and to attempt to distinguish normal aging from the effects of disease. Many influences, such as the effect of changing lifestyle, medical practices and environmental factors with time must be considered when designing and interpreting such studies. Cross-cultural differences manifest in comparing different studies must also be accounted for, but alternately provide a tool to distinguish between endogenous and exogenous factors influencing human aging. The first stage of the longitudinal study of 70 year olds in Gothenburg, Sweden, a cross-sectional survey performed in 1971, is compared to a similar cross-sectional survey performed in Jerusalem in 1991 as part of a projected longitudinal study. The similarities between the two cohorts with regard to living conditions, functional independence and disease prevalence are striking. There are also significant contrasts that reflect the 20 years that elapsed between the execution of the two studies, as well as the cultural and social differences. In particular, the ethnic diversity of the Jerusalem population, hailing from 40 separate countries, is emphasized. The comparison of these two studies highlights many of the principles critical to the role of longitudinal cohort studies in gerontology. PMID:8816868

  14. Giftedness, Trauma, and Development: A Qualitative, Longitudinal Case Study

    ERIC Educational Resources Information Center

    Peterson, Jean Sunde

    2014-01-01

    A qualitative, longitudinal, phenomenological case study explored how a gifted female experienced various life events and aspects of development during adolescence and young adulthood (ages 15-30 years), particularly as related to multiple traumatic experiences, which were revealed late in the first year of the study. Additional experiences, well…

  15. Homeschooling Education: Longitudinal Study of Methods, Materials, and Curricula

    ERIC Educational Resources Information Center

    Hanna, Linda G.

    2012-01-01

    In a comprehensive study of two-hundred fifty homeschooling families in urban, rural and suburban areas of the Commonwealth of Pennsylvania, the researcher examined all aspects of the instruction, materials and curricula employed by the families in a ten-year longitudinal study from 1998 through 2008. The researcher conducted interviews and…

  16. Career Trajectories of Dutch Pop Musicians: A Longitudinal Study

    ERIC Educational Resources Information Center

    Zwaan, Koos; ter Bogt, Tom F. M.; Raaijmakers, Quinten

    2010-01-01

    Systematic studies of artistic careers are scarce and this is the first large-scale study on the career development of pop musicians. Using a prospective longitudinal approach we followed a sample of aspiring pop musicians in the Netherlands (N=369) over a three-year period. First we identified four groups of pop musicians with different career…

  17. Suprasegmental Phonology Development and Reading Acquisition: A Longitudinal Study

    ERIC Educational Resources Information Center

    Calet, Nuria; Gutiérrez-Palma, Nicolás; Simpson, Ian C.; González-Trujillo, M. Carmen; Defior, Sylvia

    2015-01-01

    Previous studies implicate suprasegmental phonology in reading acquisition. However, little is known about how suprasegmental sensitivity develops or how it contributes to reading. Here, 130 Spanish primary-school children participated in this 2-year longitudinal study. Nonlinguistic rhythm, lexical-stress sensitivity and metrical-stress…

  18. English as a Foreign Language Spelling Development: A Longitudinal Study

    ERIC Educational Resources Information Center

    Kahn-Horwitz, Janina; Sparks, Richard L.; Goldstein, Zahava

    2012-01-01

    English as a foreign language (EFL) spelling was examined longitudinally three times (4th, 9th, 12th grades) during 9 years of EFL study among Hebrew first language (L1) students. The study examined the impact of L1 literacy variables including phonemic awareness, word attack, and spelling on EFL spelling and the relationship between EFL literacy…

  19. A Longitudinal Case Study of Curriculum Genres, K-3

    ERIC Educational Resources Information Center

    Chapman, Marilyn

    2002-01-01

    I have presented the findings from a longitudinal case study of one child's writing from kindergarten to grade 3, across different curriculum contexts, with a focus on writing in mathematics, social studies, science, and music. I describe changes in textual features of the child's writing over time, which support Newkirk's (1987) developmental…

  20. Predictors of Educational Attainment in the Chicago Longitudinal Study

    ERIC Educational Resources Information Center

    Ou, Suh-Ruu; Reynolds, Arthur J.

    2008-01-01

    The authors investigated a comprehensive set of predictors of high school completion and years of completed education for youth in the Chicago Longitudinal Study, an ongoing investigation of over 1500 low-income, minority children who grew up on high-poverty neighborhoods. The study sample included 1286 youth for whom educational attainment could…

  1. Investigating Sexual Abuse: Findings of a 15-Year Longitudinal Study

    ERIC Educational Resources Information Center

    McCormack, Bob; Kavanagh, Denise; Caffrey, Shay; Power, Anne

    2005-01-01

    Background: There is a lack of longitudinal large-scale studies of sexual abuse in intellectual disability services. Such studies offer opportunities to examine patterns in disclosure, investigation and outcomes, and to report on incidence and trends. Methods: All allegations of sexual abuse (n = 250) involving service users as victims or…

  2. The Longitudinal Study (LAS): Thirteen Year Follow-Up.

    ERIC Educational Resources Information Center

    Glenn, Christopher M.

    This study is the fifth assessment in an 18-year longitudinal study begun in 1986 to follow a group of Montessori students who attended the Franciscan Montessori Earth School in Portland, Oregon. Participating were 45 students with an average age of 18 years, about half of whom were in high school and half in college. Students completed an online…

  3. 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.

  4. 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.

  5. Towards short wavelengths FELs workshop

    SciTech Connect

    Ben-Zvi, I.; Winick, H.

    1993-12-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FELs offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FELs will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program.

  6. Generalization of Rare Variant Association Tests for Longitudinal Family Studies.

    PubMed

    Chien, Li-Chu; Hsu, Fang-Chi; Bowden, Donald W; Chiu, Yen-Feng

    2016-02-01

    Given the functional relevance of many rare variants, their identification is frequently critical for dissecting disease etiology. Functional variants are likely to be aggregated in family studies enriched with affected members, and this aggregation increases the statistical power to detect rare variants associated with a trait of interest. Longitudinal family studies provide additional information for identifying genetic and environmental factors associated with disease over time. However, methods to analyze rare variants in longitudinal family data remain fairly limited. These methods should be capable of accounting for different sources of correlations and handling large amounts of sequencing data efficiently. To identify rare variants associated with a phenotype in longitudinal family studies, we extended pedigree-based burden (BT) and kernel (KS) association tests to genetic longitudinal studies. Generalized estimating equation (GEE) approaches were used to generalize the pedigree-based BT and KS to multiple correlated phenotypes under the generalized linear model framework, adjusting for fixed effects of confounding factors. These tests accounted for complex correlations between repeated measures of the same phenotype (serial correlations) and between individuals in the same family (familial correlations). We conducted comprehensive simulation studies to compare the proposed tests with mixed-effects models and marginal models, using GEEs under various configurations. When the proposed tests were applied to data from the Diabetes Heart Study, we found exome variants of POMGNT1 and JAK1 genes were associated with type 2 diabetes. PMID:26783077

  7. Criminal Victimization and Crime Risk Perception: A Multilevel Longitudinal Study

    ERIC Educational Resources Information Center

    Russo, Silvia; Roccato, Michele; Vieno, Alessio

    2013-01-01

    In a national sample of the Italian population, surveyed four times between October 2002 and January 2007 (N = 2,008), we performed a multilevel longitudinal study aimed at predicting the increase in crime risk perception as a function of three families of independent variables, respectively lying at the within individual level (direct…

  8. Anxiety Sensitivity and Panic Attacks: A 1-Year Longitudinal Study

    ERIC Educational Resources Information Center

    Li, Wen; Zinbarg, Richard E.

    2007-01-01

    The hypothesis that anxiety sensitivity (AS) is a risk factor for panic genesis has obtained compelling support, but the clinical/practical importance of AS in panic genesis has been questioned. In addition, the association between panic experience and AS increase has not been clearly demonstrated. Through this 1-year longitudinal study among…

  9. A Longitudinal Study of Principals' Activities and Student Performance

    ERIC Educational Resources Information Center

    May, Henry; Huff, Jason; Goldring, Ellen

    2012-01-01

    Although a substantial amount of research on school leadership has focused on what principals may do to improve teaching and learning, little of this research has explored how principals' time spent on leadership activities may relate to and possibly affect student performance. This article presents results from a 3-year longitudinal study of…

  10. Minor Delinquency and Immigration: A Longitudinal Study among Male Adolescents

    ERIC Educational Resources Information Center

    Titzmann, Peter F.; Silbereisen, Rainer K.; Mesch, Gustavo

    2014-01-01

    On the basis of general theories of delinquency and the specific situation of immigrants, this longitudinal study investigated predictors of initial levels and rates of change in delinquency among 188 male ethnic German Diaspora immigrants from the former Soviet Union (FSU) in Germany, 237 male native German adolescents, and 182 male Jewish…

  11. NATIONAL LONGITUDINAL MORTALITY STUDY- NATIONAL DEATH INDEX RECORD LINKAGE (NLMS)

    EPA Science Inventory

    National Longitudinal Mortality Study is to investigate social, economic, demographic and occupational differentials in mortality (total and by cause) within a national sample of the U.S. population. In a collaboration begun in 1999 with the Census Bureau and other federal agenci...

  12. A Longitudinal Study on Internship Effectiveness in Vocational Higher Education

    ERIC Educational Resources Information Center

    Wan, Chin-Sheng; Yang, Jen-te; Cheng, Shu-yun; Su, Chiakai

    2013-01-01

    A cooperative education experience (or internship placement) is an essential component of the curricula of vocational higher education. The efficacy of internship placements has become one of the major concerns facing those who develop education curricula. The purpose of this longitudinal study was to explore the relationships among the…

  13. A Longitudinal Study of Early Adolescent Precursors to Running Away

    ERIC Educational Resources Information Center

    Tyler, Kimberly A.; Bersani, Bianca E.

    2008-01-01

    Although previous research has examined correlates of running away among samples of currently homeless and runaway adolescents, little is known about what factors will predict the likelihood that a housed adolescent with no prior history of running away will leave home. As such, the current study uses the National Longitudinal Survey of Youth to…

  14. Attachment from Infancy to Adulthood: The Major Longitudinal Studies

    ERIC Educational Resources Information Center

    Grossmann, Klaus E., Ed.; Grossmann, Karin, Ed.; Waters, Everett, Ed.

    2005-01-01

    This volume provides unique and valuable firsthand accounts of the most important longitudinal studies of attachment. Presented are a range of research programs that have broadened the understanding of early close relationships and their role in individual adaptation throughout life. In addition to discussing the findings that emerged from each…

  15. Longitudinal Study on Reciprocity between Personality Traits and Parenting Stress

    ERIC Educational Resources Information Center

    Rantanen, Johanna; Tillemann, Kati; Metsäpelto, Riitta-Leena; Kokko, Katja; Pulkkinen, Lea

    2015-01-01

    Reciprocal associations between the Big Five personality traits and parenting stress--including both parents' feelings of their distress and perception of their incompetence as parents--were studied with 248 participants (49% of which were males). Longitudinal data, collected at ages 33/36, 42 and 50 years, were used. Cross-lagged path…

  16. Stages of Headship: A Longitudinal Study of the Principalship.

    ERIC Educational Resources Information Center

    Weindling, Dick

    This paper uses socialization theory to re-examine a unique, 10-year longitudinal study of headteachers so as to describe the stages of headship transition. It outlines prior models of leadership succession in both business and schools and produces a stage theory of headship that can be used not only as a research tool, but also as a way to assist…

  17. Assessing CLIL at Primary School: A Longitudinal Study

    ERIC Educational Resources Information Center

    Serra, Cecilia

    2007-01-01

    This paper presents aspects of a longitudinal study assessing integrative bilingual learning based on Content and Language Integrated Learning (CLIL), implemented in three Swiss primary schools. From Grades 1 to 6, three classes of German-speaking pupils were taught 50% of the curriculum, notably mathematics, in Italian or in Romansh as a second…

  18. Document Use during a Research Project: A Longitudinal Study.

    ERIC Educational Resources Information Center

    Wang, Peiling; White, Marilyn Domas

    1995-01-01

    Provides preliminary results of a longitudinal, qualitative research study of document use by academic agricultural economists in actual situations. Topics include users' changing information needs, use patterns, decision making regarding relevant items, and criteria and decision rules used to read or cite documents across stages of research.…

  19. A Longitudinal Study of Pretend Play in Autism

    ERIC Educational Resources Information Center

    Rutherford, M. D.; Young, Gregory S.; Hepburn, Susan; Rogers, Sally J.

    2007-01-01

    This study describes a longitudinal design (following subjects described in Rutherford & Rogers [2003, "Journal of Autism and Developmental Disorder", 33, 289-302]) to test for predictors of pretend play competence in a group of children with autism. We tested the hypothesis that developmental change in pretend play performance can be predicted by…

  20. A Longitudinal Study of the Impact of an Environmental Action

    ERIC Educational Resources Information Center

    Rioux, Liliane; Pasquier, Daniel

    2013-01-01

    In a previous study, we investigated the impact of an awareness-raising campaign on the behaviour of secondary school children in the Centre Region of France, regarding the recycling of used batteries. But, was it a question of pro-environmental behaviour or simply an environmental action? To answer this question, a three-year longitudinal study…

  1. Exploring Dynamism in Willingness to Communicate: A Longitudinal Case Study

    ERIC Educational Resources Information Center

    Cao, Yiqian Katherine

    2013-01-01

    This paper examines dynamism in students' situational willingness to communicate (WTC) within a second language classroom. This longitudinal study involved twelve English as a Second Language (ESL) participants who enrolled in an English for Academic Purposes (EAP) programme in New Zealand for five months. Based on data from classroom…

  2. Secondary Analysis of National Longitudinal Transition Study 2 Data

    ERIC Educational Resources Information Center

    Hicks, Tyler A.; Knollman, Greg A.

    2015-01-01

    This review examines published secondary analyses of National Longitudinal Transition Study 2 (NLTS2) data, with a primary focus upon statistical objectives, paradigms, inferences, and methods. Its primary purpose was to determine which statistical techniques have been common in secondary analyses of NLTS2 data. The review begins with an…

  3. Pain Perceptions of the Oldest Old: A Longitudinal Study

    ERIC Educational Resources Information Center

    Zarit, Steven H.; Griffiths, Patricia C.; Berg, Stig

    2004-01-01

    Purpose: This study assessed self-reported pain in the oldest old and examined its changes over time and in relation to other measures of health and functioning. Design and Methods: A population-based sample of the oldest old (86-92 years of age) residing in Sweden who were participating in a multiwave longitudinal investigation were interviewed…

  4. Early Cognitive Profiles of Emergent Readers: A Longitudinal Study

    ERIC Educational Resources Information Center

    Brunswick, Nicola; Martin, G. Neil; Rippon, Georgina

    2012-01-01

    This longitudinal study examined the contribution of phonological awareness, phonological memory, and visuospatial ability to reading development in 142 English-speaking children from the start of kindergarten to the middle of Grade 2. Partial cross-lagged analyses revealed significant relationships between early performance on block design and…

  5. Connecticut Participation in the National Educational Longitudinal Study (NELS).

    ERIC Educational Resources Information Center

    Connecticut State Department of Education Research Bulletin, 1990

    1990-01-01

    Statewide information concerning the Connecticut eight-grade public school students who particpated in the National Education Longitudinal Study (NELS) in the spring of 1988 is presented. Over 900 students in 46 schools in 35 school districts, almost evenly divided between males and females, completed cognitive tests and student surveys about…

  6. Planning Papers for the National Longitudinal Study of Chapter 1.

    ERIC Educational Resources Information Center

    Policy Studies Associates, Inc., Washington, DC.

    The Elementary and Secondary School Improvement Amendments of 1988 (P.L. 100-297) require the U.S. Department of Education to conduct a national longitudinal study of Chapter 1 of the Elementary Secondary Education Act (ESEA). The department commissioned the selection of experts qualified to provide design suggestions and advice for the national…

  7. Experimental study of the longitudinal instability for beam transport

    SciTech Connect

    Reiser, M.; Wang, J.G.; Guo, W.M.; Wang, D.X.

    1990-01-01

    Theoretical model for beam longitudinal instability in a transport pipe with general wall impedance is considered. The result shows that a capacitive wall tends to stabilize the beam. The experimental study of the instability for a pure resistive-wall is presented, including the design parameters, setup and components for the experiment. 6 refs., 3 figs.

  8. A Longitudinal Study of Consumer Socialization.

    ERIC Educational Resources Information Center

    Moschis, George P.; Moore, Roy L.

    A study examined the effects of factors (including television, family, peers, age, and socioeconomic status) on consumer socialization, the process by which individuals develop consumption-related cognitions and behaviors. The specific criterion variables studied included consumer affairs knowledge, puffery filtering, consumer finance management,…

  9. Factors affecting longitudinal trajectories of plasma sphingomyelins: the Baltimore Longitudinal Study of Aging

    PubMed Central

    Mielke, Michelle M; Bandaru, Veera Venkata Ratnam; Han, Dingfen; An, Yang; Resnick, Susan M; Ferrucci, Luigi; Haughey, Norman J

    2015-01-01

    Sphingomyelin metabolism has been linked to several diseases and to longevity. However, few epidemiological studies have quantified individual plasma sphingomyelin species (identified by acyl-chain length and saturation) or their relationship between demographic factors and disease processes. In this study, we determined plasma concentrations of distinct sphingomyelin species in 992 individuals, aged 55 and older, enrolled in the Baltimore Longitudinal Study of Aging. Participants were followed, with serial measures, up to 6 visits and 38 years (3972 total samples). Quantitative analyses were performed on a high-performance liquid chromatography-coupled electrospray ionization tandem mass spectrometer. Linear mixed models were used to assess variation in specific sphingomyelin species and associations with demographics, diseases, medications or lifestyle factors, and plasma cholesterol and triglyceride levels. We found that most sphingomyelin species increased with age. Women had higher plasma levels of all sphingomyelin species and showed steeper trajectories of age-related increases compared to men. African Americans also showed higher circulating sphingomyelin concentrations compared to Caucasians. Diabetes, smoking, and plasma triglycerides were associated with lower levels of many sphingomyelins and dihydrosphingomyelins. Notably, these associations showed specificity to sphingomyelin acyl-chain length and saturation. These results demonstrate that longitudinal changes in circulating sphingomyelin levels are influenced by age, sex, race, lifestyle factors, and diseases. It will be important to further establish the intra-individual age- and sex-specific changes in each sphingomyelin species in relation to disease onset and progression. PMID:25345489

  10. Simulation of a regenerative MW FEL amplifier

    SciTech Connect

    Nguyen, R.T.; Colson, W.B.; Wong, R.K.; Sheffield, R.L.

    1997-08-01

    Both oscillator and regenerative amplifier configurations are being studied to optimize the design of a MW class FEL. The regenerative amplifier uses a longer undulator and relies on higher extraction efficiency to achieve high average power, whereas the oscillator is a more compact overall design requiring the transport of the high energy electron beam around bends for energy recovery. Using parameters extrapolated from the 1 kW LANL regenerative amplifier, simulations study the feasibility of achieving 1 MW average power.

  11. FEL on slow cyclotron wave

    SciTech Connect

    Silivra, A.

    1995-12-31

    A physical mechanism of interaction of fast electromagnetic wave with slow cyclotron wave of relativistic electron beam in a FEL with helical wiggler field is described. It is shown that: (1) interaction is possible for both group of steady state electron trajectories (2) positive gain is achieved within certain interval of guide field strength (3) operation wavelength for group 1 trajectories ({Omega}{sub 0}/{gamma} < k{omega}{upsilon}{parallel}) is shorter than for the conventional FEL synchronism. A nonlinear analysis shows that efficiency of slow cyclotron FEL is restricted mainly by a breakdown of a single electron synchronism due to dependence of (modified) electron cyclotron frequency on an energy of electron. Nevertheless, as numerical simulation shows, typical efficiency of 15 % order is achieved in millimeter wavelength band for the midrelativistic ({gamma}= 3 {divided_by} 4) slow cyclotron wave FEL. Tapering of magnetic field results in a substantial increase of efficiency.

  12. Tourism Degree Internships: A Longitudinal Study

    ERIC Educational Resources Information Center

    Busby, Graham

    2003-01-01

    This case study briefly reviews the development of tourism degrees in the United Kingdom before considering the experiences obtained by students on year-long internship programmes over a period of 8 years. Verbatim confidential comments, from students, are provided and specific transferable skills discussed. Whilst some skills can be developed…

  13. Method for Studying Helicopter Longitudinal Maneuver Stability

    NASA Technical Reports Server (NTRS)

    Amer, Kenneth B

    1954-01-01

    A theoretical analysis of helicopter maneuver stability is made and the results are compared with experimental results for both a single and a tandem rotor helicopter. Techniques are described for measuring in flight the significant stability derivatives for use with the theory to aid in design studies of means for achieving marginal maneuver stability for a prototype helicopter.

  14. Young Children's Improvisations: A Longitudinal Study.

    ERIC Educational Resources Information Center

    Flohr, John W.

    The purpose of this study was to characterize the behavior of 2-, 3-, 4-, and 5-year-old children engaged in improvisational musical tasks. Ten subjects from each of the four age levels participated in the 4-year investigation, which lasted until the 2-year-olds reached 5 years of age. Children met individually with the investigator for 15 minutes…

  15. Concepts for NASA longitudinal health studies

    NASA Technical Reports Server (NTRS)

    Nicogossian, A. E.; Pool, S. L.; Leach, C. S.; Moseley, E.; Rambaut, P. C.

    1983-01-01

    Clinical data collected from a 15-year study of the homogenous group of pre-Shuttle astronauts have revealed no significant long-term effects from spaceflight. The current hypothesis suggests that repeated exposures to the space environment in the Shuttle era will similarly have no long-term health effects. However, a much more heterogenous group of astronauts and non-astronaut scientists will fly in Shuttle, and data on this group's adaptation to the space environment and readaptation to earth are currently sparse. In addition, very little information is available concerning the short- and long-term medical consequences of long duration exposure to space and subsequent readaptation to the earth environment. In this paper, retrospective clinical information on astronauts is reviewed and concepts for conducting epidemiological studies examining long-term health effects of spaceflight on humans, including associated occupational risks factors, are presented.

  16. A longitudinal study of administrative segregation.

    PubMed

    O'Keefe, Maureen L; Klebe, Kelli J; Metzner, Jeffrey; Dvoskin, Joel; Fellner, Jamie; Stucker, Alysha

    2013-01-01

    The use of administrative segregation for inmates with and without mental illness has generated considerable criticism. Segregated inmates are locked in single cells for 23 hours per day, are subjected to rigorous security procedures, and have restricted access to programs. In this study, we examined whether inmates in segregation would show greater deterioration over time on psychological symptoms than would comparison offenders. The subjects were male inmates, with and without mental illness, in administrative segregation, general population, or special-needs prison. Subjects completed the Brief Symptom Inventory at regular intervals for one year. Results showed differentiation between groups at the outset and statistically significant but small positive change over time across all groups. All groups showed the same change pattern such that there was not the hypothesized differential change of inmates within administrative segregation. This study advances the empirical research, but replication research is needed to make a better determination of whether and under what conditions harm may or may not occur to inmates in solitary confinement. PMID:23503176

  17. Ophthalmologic complications of meningomyelocele: a longitudinal study.

    PubMed Central

    Biglan, A W

    1990-01-01

    Patients with spina bifida have multiple ophthalmologic problems, many of which are preventable. Most of the problems are related to the hydrocephalus, which is caused by the coexisting Arnold-Chiari malformation. When patients are treated for hydrocephalus, and comprehensive eye care is available, 94% of the patients will have 6/12 visual acuity or better. Strabismus is common but it responds well to medical and surgical treatment. Children with spina bifida should have frequent examinations by an ophthalmologist who is familiar with the diagnosis and management of the defects recorded in this study. Images FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 FIGURE 11 FIGURE 12 PMID:2095031

  18. Photon Source Capabilities of the Jefferson Lab FEL

    SciTech Connect

    Benson, S. V.; Douglas, D. R.; Evtushenko, P.; Hannon, F. E.; Hernandez-Garcia, C.; Klopf, J. M.; Legg, R. A.; Neil, G. R.; Shinn, M. D.; Tennant, C. D.; Zhang, S.; Williams, G. P.

    2013-03-22

    Jefferson Lab operates a superconducting energy recovered linac which is operated with CW RF and which powers oscillator-based IR and UV Free Electron Lasers (FELs) with diffraction limited sub-picosecond pulses with >10{sup 13} photons per pulse (1.0%BW) at pulse repetition frequencies up to 75 MHz. Useful harmonics extend into the vacuum ultraviolet (VUV). Based on FEL model calculations validated using this facility, we have designed both an oscillator-based VUV-FEL that would produce 6 10{sup12} coherent (0.5% BW) 100 eV photons per pulse at multi-MHz repetition rates in the fundamental, and a dual FEL configuration that would allow simultaneous lasing lasing at THz and UV wavelengths. The VUV-FEL would utilize a novel high gain, low Q cavity, while the THz source would be an FEL oscillator with a short wiggler providing diffraction limited pulses with pulse energy exceeding 50 microJoules. The THz source would use the exhaust beam from a UVFEL. Such multiphoton capabilities would provide unique opportunities for out of equilibrium dynamical studies at time-scales down to 50 fs. The fully coherent nature of all these sources results in peak and average brightness values that are many orders of magnitude higher than storage rings. We acknowledge support from the Commonwealth of Virginia. Jefferson Lab is supported by the U.S. DOE under Contract No. DE-AC05-84-ER40150.

  19. Beam Conditioning for FELs: Consequences and Methods

    SciTech Connect

    Wolski, Andrzej; Penn, Gregory; Sessler, Andrew; Wurtele, Jonathan

    2003-10-09

    The consequences of beam conditioning in four example cases (VISA, a Soft X-Ray FEL, LCLS and a ''Greenfield'' FEL) are examined. It is shown that in emittance limited cases, proper conditioning reduces sensitivity to the transverse emittance, and allows stronger focusing in the undulator. Simulations show higher saturation power, with gain lengths reduced up to a factor of two. The beam dynamics in a general conditioning system are studied, with ''matching conditions'' derived for achieving conditioning without growth in effective emittance. Various conditioners are considered, and expressions derived for the amount of conditioning provided in each case when the matching conditions are satisfied. We discuss the prospects for conditioners based on laser and plasma systems.

  20. Beam conditioning for FELs: Consequences and methods

    SciTech Connect

    Wolski, A.; Penn, G.; Sessler, A.; Wurtele, J.

    2004-06-29

    The consequences of beam conditioning in four example cases (VISA, a Soft X-Ray FEL, LCLS and a ''Greenfield'' FEL) are examined. It is shown that in emittance limited cases, proper conditioning reduces sensitivity to the transverse emittance and, furthermore, allows for stronger focusing in the undulator. Simulations show higher saturation power, with gain lengths reduced by a factor of two or more. The beam dynamics in a general conditioning system are studied, with ''matching conditions'' derived for achieving conditioning without growth in the effective emittance. Various conditioning lattices are considered, and expressions derived for the amount of conditioning provided in each case when the matching conditions are satisfied. These results show that there is no fundamental obstacle to producing beam conditioning, and that the problem can be reduced to one of proper lattice design. Nevertheless, beam conditioning will not be easy to implement in practice.

  1. Proposal for a IR waveguide SASE FEL at the PEGASUS injector

    NASA Astrophysics Data System (ADS)

    Reiche, S.; Rosenzweig, J.; Telfer, S.

    2001-12-01

    Free Electron Lasers up to the visible regime are dominated by diffraction effects, resulting in a radiation size much larger than the electron beam. Thus the effective field amplitude at the location of the electron beam, driving the FEL process, is reduced. By using a waveguide, the radiation field is confined within a smaller aperture and an enhancement of the FEL performance can be expected. The PEGASUS injector at UCLA will be capable to provide the brilliance needed for an IR SASE FEL. The experiment Power Enhanced Radiation Source Experiment Using Structures (PERSEUS) is proposed to study the physics of a waveguide SASE FEL in a quasi 1D environment, where diffraction effects are strongly reduced as it is the case only for future FELs operating in the VUV and X-ray regime. The expected FEL performance is given by this presentation.

  2. Short wavelength FELs using the SLAC linac

    SciTech Connect

    Winick, H.; Bane, K.; Boyce, R.

    1993-08-01

    Recent technological developments have opened the possibility to construct a device which we call a Linac Coherent Light Source (LCLS); a fourth generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much aborter wavelength than the 240 mn that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3-100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by Self-Amplified-Spontaneous-Emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops.

  3. Staged energy cascades for the LUX FEL

    SciTech Connect

    Penn, G.

    2004-07-27

    Designs and simulation studies for harmonic cascades, consisting of multiple stages of harmonic generation in free electron lasers (FELs), are presented as part of the LUX R&D project to design ultrafast, high photon energy light sources for basic science. Beam energies of 1.1, 2.1, and 3.1 GeV, corresponding to each pass through a recirculating linac, have independent designs for the harmonic cascade. Simulations were performed using the GENESIS FEL code, to obtain predictions for the performance of these cascades over a wide range of photon energies in terms of the peak power and laser profile. The output laser beam consists of photon energies of up to 1 keV, with durations of the order of 200 fs or shorter. The contribution of shot noise to the laser output is minimal, however fluctuations in the laser and electron beam properties can lead to variations in the FEL output. The sensitivity of the cascade to electron beam properties and misalignments is studied, taking advantage of the fact that GENESIS is a fully 3-dimensional code.

  4. A longitudinal study of gender-related cognition and behaviour.

    PubMed

    Campbell, Anne; Shirley, Louisa; Candy, Julia

    2004-02-01

    Gender schema theory proposes that children's acquisition of gender labels and gender stereotypes informs gender-congruent behaviour. Most previous studies have been cross-sectional and do not address the temporal relationship between knowledge and behaviour. We report the results of a longitudinal study of gender knowledge and sex-typed behaviour across three domains in children tested at 24 and 36 months (N = 56). Although both knowledge and sex-typed behaviour increased significantly between 2 and 3 years, there was no systematic pattern of cross-lagged correlations between the two, although some concurrent relationships were present at 24 months. Future longitudinal work might profitably focus on younger children using reliable preverbal measures of gender knowledge and employing a shorter lag between measurement times. PMID:15323112

  5. Managing Endings in a Longitudinal Study: Respect for Persons

    NASA Astrophysics Data System (ADS)

    Reiss, Michael J.

    2005-03-01

    In this paper I describe and discuss the way that a book I had written on a five-year longitudinal study of school science teaching was received by the pupils and teachers it featured. By and large the pupils' reception was positive. However, one group of teachers was deeply hurt by the book. I trace this mainly to my failure to consider adequately their fears of the consequences of the book's publication and possibly to my failure to consider with them the psychological significance of my withdrawing from the school after five years of regular study. I hope that there are lessons not only for myself but also for others considering longitudinal and ethnographic research in science education and more broadly.

  6. Cohort profile: the Amsterdam Growth and Health Longitudinal Study.

    PubMed

    Wijnstok, Nienke J; Hoekstra, Trynke; van Mechelen, Willem; Kemper, Han C G; Twisk, Jos W R

    2013-04-01

    The Amsterdam Growth and Health Longitudinal Study (AGHLS) is a unique, multidisciplinary cohort study that was initially set up to examine growth and health among teenagers. Throughout the years, the AGHLS has aimed to answer research questions dealing with the relationships between the (natural) development of anthropometry, lifestyle and health from adolescence into adulthood. The AGHLS specifically focuses on anthropometrics, physical activity and fitness, cardiovascular disease risk, lifestyle, musculoskeletal health, psychological health and well-being. Besides this, many methodological issues related to the analysis of longitudinal data were also explored within the framework of the AGHLS. In 1976, students from two secondary schools from the greater Amsterdam area were included in the study. Between 1976 and 2006, 10 rounds of measurement were performed covering an age range between 13 and 43 years. The huge database collected so far has been primarily used to answer relevant research questions regarding the longitudinal relationship between lifestyle and health. Further information about the study can be obtained from the principal investigator Jos Twisk (jwr.twisk@vumc.nl), and up-to-date information on AGHLS can be found by visiting the website www.aggo.nl. PMID:22434862

  7. Web-based tracking methods in longitudinal studies.

    PubMed

    Williams, Izaak L; O'Donnell, Clifford R

    2014-08-01

    The use of online resources to reduce the attrition of program participants in longitudinal studies is examined. Higher-risk individuals, those involved in illegal activities, and females with last name changes are typically more difficult to locate. The effectiveness of using online resources for these participants is addressed. These resources include social networking sites, people-finder search engines, telephone and address directories, judicial records, and death records. The strengths and limitations of these resources are presented and discussed. Longitudinal studies using these resources are examined to evaluate their successful follow-up rates. The results of these studies indicate that participant characteristics are more important to successful follow-up than the length of time since participation or sample size. The use of multiple online sites increased follow-up rates, especially for those who are typically difficult to locate. The variables and websites to consider are discussed, and six lessons learned are offered. The prospective use of online participant involvement is especially important for successful longitudinal evaluation and program planning. PMID:24769078

  8. Nonlinear harmonic generation in the STARS FEL

    NASA Astrophysics Data System (ADS)

    Abo-Bakr, M.; Goldammer, K.; Kamps, T.; Knobloch, J.; Kuske, B.; Leitner, T.; Meseck, A.

    2008-08-01

    BESSY proposes to build STARS, an FEL to demonstrate cascaded High Gain Harmonic Generation (HGHG). In two HGHG stages, a laser source of 700-900 nm is converted down to a wavelength of 40-70 nm. The STARS facility consists of a normal-conducting RF photoinjector, three superconducting TESLA-type acceleration modules, a magnetic bunch compressor and two stages of HGHG, each consisting of a modulator, dispersive chicane and a radiator. At the entrance of the undulator section, the beam energy is 325 MeV and the peak current is about 500 A. With these parameters, the STARS FEL reaches saturation with a peak power of 100-350 MW. A superradiant mode is also foreseen which boosts the radiation power to the GW-level. Due to nonlinear harmonic generation (NHG), free electron lasers also radiate coherently at higher harmonics of the FEL resonant frequency. STARS can hence extend its output range to even shorter wavelengths. This paper presents studies of the STARS harmonic content in the wavelength range of 6-20 nm. Seeding with high harmonic generation pulses at 32 nm is also discussed.

  9. Future metrology needs for FEL reflective optics.

    SciTech Connect

    Assoufid, L.

    2000-09-21

    An International Workshop on Metrology for X-ray and Neutron Optics has been held March 16-17, 2000, at the Advanced Photon Source, Argonne National Laboratory, near Chicago, Illinois (USA). The workshop gathered engineers and scientists from both the U.S. and around the world to evaluate metrology instrumentation and methods used to characterize surface figure and finish for long grazing incidence optics used in beamlines at synchrotrons radiation sources. This two-day workshop was motivated by the rapid evolution in the performance of x-ray and neutron sources along with requirements in optics figure and finish. More specifically, the performance of future light sources, such as free-electron laser (FEL)-based x-ray sources, is being pushed to new limits in term of both brilliance and coherence. As a consequence, tolerances on surface figure and finish of the next generation of optics are expected to become tighter. The timing of the workshop provided an excellent opportunity to study the problem, evaluate the state of the art in metrology instrumentation, and stimulate innovation on future metrology instruments and techniques to be used to characterize these optics. This paper focuses on FEL optics and metrology needs. (A more comprehensive summary of the workshop can be found elsewhere.) The performance and limitations of current metrology instrumentation will be discussed and recommendations from the workshop on future metrology development to meet the FEL challenges will be detailed.

  10. Harmonic cascade FEL designs for LUX

    SciTech Connect

    Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.

    2004-07-16

    LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.

  11. The universal method for optimization of undulator tapering in FEL amplifiers

    NASA Astrophysics Data System (ADS)

    Schneidmiller, E. A.; Yurkov, M. V.

    2015-05-01

    Technique of undulator tapering in the post-saturation regime is used at the existing x-ray FELs for increasing the radiation power. There are also discussions on the future of high peak and average power FELs for scientific and industrial applications. Diffraction effects essentially influence on the choice of the tapering strategy. Recent studies resulted in an general law of the undulator tapering for a seeded FEL amplifier. In this paper we extend these results for the case of the Self Amplified Spontaneous Emission (SASE) FEL.

  12. Hypoallergenic derivatives of Fel d 1 obtained by rational reassembly for allergy vaccination and tolerance induction

    PubMed Central

    Curin, M.; Weber, M.; Thalhamer, T.; Swoboda, I.; Focke-Tejkl, M.; Blatt, K.; Valent, P.; Marth, K.; Garmatiuk, T.; Grönlund, H.; Thalhamer, J.; Spitzauer, S.; Valenta, R.

    2015-01-01

    Summary Background and objective The major cat allergen Fel d 1 represents one of the most important respiratory allergens. Aim of this study was to engineer recombinant Fel d 1 derivatives with reduced IgE reactivity and preserved T cell epitopes for vaccination and tolerance induction. Methods Seven recombinant mosaic proteins were generated by reassembly of non-IgE-reactive peptides of Fel d 1 which contained the sequence elements for induction of allergen-specific blocking IgG antibodies and T cell epitopes. Mosaic proteins were expressed in Escherichia coli using codon-optimized synthetic genes and compared with Fel d 1 regarding structural fold by circular dichroism, IgE-binding capacity, activation of allergic patients’ basophils and ability to induce allergen-specific blocking IgG antibodies upon immunization. Results Although each of the mosaic proteins had lost the alpha-helical fold typical for Fel d 1, a strong reduction in IgE reactivity as well as allergenic activity in basophil activation assays was only obtained for three constructs, two reassembled fragments (Fel d 1 MB, Fel d 1 MC) and a fusion of the latter two (Fel d 1 MF) in which the cysteines of Fel d 1 MC were replaced by serines. Immunization of rabbits with Fel d 1 MB, MC and MF induced high levels of IgG antibodies that inhibited IgE reactivity of cat-allergic patients to Fel d 1 in a comparable manner as IgG induced with the wild-type allergen. Conclusions We report the development of hypoallergenic reassembled Fel d 1 proteins suitable for vaccination and tolerance induction in cat-allergic patients. PMID:24552249

  13. Residents’ perceptions of an integrated longitudinal curriculum: a qualitative study

    PubMed Central

    Lubitz, Rebecca; Lee, Joseph; Hillier, Loretta M.

    2015-01-01

    Background The purpose of this study was to explore family medicine residents’ perceptions of a newly restructured integrated longitudinal curriculum. Method A purposeful sample of 16 family medicine residents participated in focus group interviews conducted from a grounded theory perspective to identify the characteristics of this training model that contribute to and that challenge learning. Results Eight key themes were identified: continuity of care, relevance to family medicine, autonomy, program-focused preparation, professional development as facilitated by role modeling, patient volume, clarity of expectations for learners, and logistics. Positive learning experiences were marked by high levels of autonomy, continuity, and relevance to family medicine. Less favorable learning experiences were characterized by limited opportunities for continuity of care, limited relevance to family medicine practice and unclear expectations for the resident’s role. Family physician-led learning experiences contributed to residents’ understanding of the full scope of family medicine practice, more so than specialist-led experiences. The logistics of implementing the integrated block were challenging and negatively impacted continuity and learning. Conclusions This study suggests that an integrated longitudinalized family medicine block training model has the potential to support the principles of a longitudinal integrated competency-based curriculum to effectively prepare residents for family medicine practice. PMID:27004074

  14. 77 FR 20885 - Agency Information Collection (Vocational Rehabilitation and Employment Longitudinal Study Survey...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-06

    .... 2900-New (VR&E Longitudinal Study Survey)'' in any correspondence. For Further Information or a Copy of....mclamb@va.gov . Please refer to ``OMB Control No. 2900-New (VR&E Longitudinal Study Survey... Control Number: 2900-New (VR&E Longitudinal Study Survey). Type of Review: New data collection....

  15. Academic Performance of Language-Minority Students and All-Day Kindergarten: A Longitudinal Study

    ERIC Educational Resources Information Center

    Chang, Mido

    2012-01-01

    This longitudinal study examined the effect of all-day kindergarten programs on the academic achievement of students from racial language minority and low socioeconomic class. The study employed a series of 3-level longitudinal multilevel analyses using a nationally representative database, the Early Childhood Longitudinal Study (ECLS). The study…

  16. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    SciTech Connect

    BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

    2005-08-21

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

  17. [Longitudinal change in independence in the elderly--Kahoku Longitudinal Aging Study (KLAS)].

    PubMed

    Matsubayashi, K; Okumiya, K; Kawamoto, A; Kimura, S; Wada, T; Fujisawa, M; Doi, Y; Shimada, K; Ozawa, T

    1994-10-01

    A community based study named Kahoku Longitudinal Aging Study (KLAS) was conducted since 1990 for the purpose of evaluating the comprehensive geriatric functional assessment (CGA) and preventing a decline in CGA in the community-dwelling elderly population. It was carried out in a Japanese rural town, in which 32% of the population was over 65 years of age. This study included a questionnaire about activity of daily living (ADL), information-related physical function, mental (cognitive and affective) and social functional domains. In addition to subjective informative instruments, various types of objective assessment such as quantitative neuro-behavioral function tests and medical examinations were performed. Subjects were all the eligible elderly aged over 65 years in the community. Although the ratio of subjects who were independent in ADL decreased with advancing age in both 1991 and 1993, the ratio of the independent elderly in ADL became significant higher (74%) in 1993 than in 1991 (71%). Scores on 2 kinds of neurobehavioral function tests in the 159 subjects aged over 75 years who attended the examination every year showed a significant and slight decrease during two years. However, some test indices significantly improved during the 2 years. These results suggested that age-related dependency in ADL and some kind of neurobehavioral functions might be prevented, in part, by health promoting education and improvement of life style. PMID:7853739

  18. Integrative Data Analysis through Coordination of Measurement and Analysis Protocol across Independent Longitudinal Studies

    ERIC Educational Resources Information Center

    Hofer, Scott M.; Piccinin, Andrea M.

    2009-01-01

    Replication of research findings across independent longitudinal studies is essential for a cumulative and innovative developmental science. Meta-analysis of longitudinal studies is often limited by the amount of published information on particular research questions, the complexity of longitudinal designs and the sophistication of analyses, and…

  19. Study of longitudinal dynamics in space-charge dominated beams

    NASA Astrophysics Data System (ADS)

    Tian, Kai

    Modern accelerator applications, such as heavy ion fusion drivers, pulsed neutron sources, electron injectors for high-energy linear colliders, and X-ray Free Electron Lasers, demand beams with high intensity, low emittance and small energy spread. At low (non-relativistic) energies, the "electrostatic", collective interactions from space-charge forces existing in such intense beams play the dominant role; we characterize these beams as space-charge dominated beams. This dissertation presents numerous new findings on the longitudinal dynamics of a space-charge dominated beam, particularly on the propagation of density perturbations. In order to fully understand the complex physics of longitudinal space-charge waves, we combine the results of theory, computer simulation, and experiment. In the Long Solenoid Experimental system (LSE), with numerous diagnostic tools and techniques, we have, for the first time, experimentally measured the detailed energy profiles of longitudinal space-charge waves at different locations, both near the beam source and at the end of the transport system. Along with the current profiles, we have a complete set of experimental data for the propagation of space-charge waves. We compare these measured results to a 1-D theory and find better agreement for beams with perturbations in the linear regime, where the perturbation strength is less than 10%, than those with nonlinear perturbations. Using fast imaging techniques that we newly developed, we have, for the first time, obtained the progressive time-resolved images of longitudinal slices of a space-charge dominated beam. These images not only provide us time-resolved transverse density distribution of the beam, but also enable us to take time-resolved transverse phase space measurement using computerized tomography. By combining this information with the longitudinal energy measurement, we have, for the first time, experimentally constructed the full 6-D phase space. Part of the results

  20. Integrating Prospective Longitudinal Data: Modeling Personality and Health in the Terman Life Cycle and Hawaii Longitudinal Studies

    ERIC Educational Resources Information Center

    Kern, Margaret L.; Hampson, Sarah E.; Goldberg, Lewis R.; Friedman, Howard S.

    2014-01-01

    The present study used a collaborative framework to integrate 2 long-term prospective studies: the Terman Life Cycle Study and the Hawaii Personality and Health Longitudinal Study. Within a 5-factor personality-trait framework, teacher assessments of child personality were rationally and empirically aligned to establish similar factor structures…

  1. Measuring FEL Radiation Properties at VISA-FEL

    SciTech Connect

    Cornacchia, Massimo

    2002-08-21

    The VISA (Visible to Infrared SASE Amplifier) SASE free electron laser has been successfully operated at the Accelerator Test Facility (ATF) at BNL. High gain and saturation were observed at 840 nm. We describe here the diagnostic system, experimental procedures and data reduction algorithms, as the FEL performance was measured along the length of the undulator. We also discuss selected spectral radiation measurements.

  2. Cohort profile: the China Health and Retirement Longitudinal Study (CHARLS).

    PubMed

    Zhao, Yaohui; Hu, Yisong; Smith, James P; Strauss, John; Yang, Gonghuan

    2014-02-01

    The China Health and Retirement Longitudinal Study (CHARLS) is a nationally representative longitudinal survey of persons in China 45 years of age or older and their spouses, including assessments of social, economic, and health circumstances of community-residents. CHARLS examines health and economic adjustments to rapid ageing of the population in China. The national baseline survey for the study was conducted between June 2011 and March 2012 and involved 17 708 respondents. CHARLS respondents are followed every 2 years, using a face-to-face computer-assisted personal interview (CAPI). Physical measurements are made at every 2-year follow-up, and blood sample collection is done once in every two follow-up periods. A pilot survey for CHARLS was conducted in two provinces of China in 2008, on 2685 individuals, who were resurveyed in 2012. To ensure the adoption of best practices and international comparability of results, CHARLS was harmonized with leading international research studies in the Health and Retirement Study (HRS) model. Requests for collaborations should be directed to Dr Yaohui Zhao (yhzhao@nsd.edu.cn). All data in CHARLS are maintained at the National School of Development of Peking University and will be accessible to researchers around the world at the study website. The 2008 pilot data for CHARLS are available at: http://charls.ccer.edu.cn/charls/. National baseline data for the study are expected to be released in January 2013. PMID:23243115

  3. Cohort Profile: The China Health and Retirement Longitudinal Study (CHARLS)

    PubMed Central

    Zhao, Yaohui; Hu, Yisong; Smith, James P; Strauss, John; Yang, Gonghuan

    2014-01-01

    The China Health and Retirement Longitudinal Study (CHARLS) is a nationally representative longitudinal survey of persons in China 45 years of age or older and their spouses, including assessments of social, economic, and health circumstances of community-residents. CHARLS examines health and economic adjustments to rapid ageing of the population in China. The national baseline survey for the study was conducted between June 2011 and March 2012 and involved 17 708 respondents. CHARLS respondents are followed every 2 years, using a face-to-face computer-assisted personal interview (CAPI). Physical measurements are made at every 2-year follow-up, and blood sample collection is done once in every two follow-up periods. A pilot survey for CHARLS was conducted in two provinces of China in 2008, on 2685 individuals, who were resurveyed in 2012. To ensure the adoption of best practices and international comparability of results, CHARLS was harmonized with leading international research studies in the Health and Retirement Study (HRS) model. Requests for collaborations should be directed to Dr Yaohui Zhao (yhzhao@nsd.edu.cn). All data in CHARLS are maintained at the National School of Development of Peking University and will be accessible to researchers around the world at the study website. The 2008 pilot data for CHARLS are available at: http://charls.ccer.edu.cn/charls/. National baseline data for the study are expected to be released in January 2013. PMID:23243115

  4. Design and Start-to-End Simulation of an X-Band RF Driven Hard X-Ray FEL with LCLS Injector

    SciTech Connect

    Sun, Yipeng; /SLAC

    2012-08-20

    In this note, it is briefly discussed the accelerator design and start-to-end 3D macro particles simulation (using ELEGANT and GENESIS) of an X-band RF driven hard X-ray FEL with LCLS injector. A preliminary design and LiTrack 1D simulation studies were presented before in an older publication [1]. In numerical simulations this X-band RF driven hard X-ray FEL achieves/exceeds LCLS-like performance in a much shorter overall length of 350 m, compared with 1200 m in the LCLS case. One key feature of this design is that it may achieve a higher final beam current of 5 kA plus a uniform energy profile, mainly due to the employment of stronger longitudinal wake fields in the last X-band RF linac [2].

  5. Longitudinal study of workers in an aluminum smelter

    SciTech Connect

    Chan-Yeung, M.; Enarson, D.A.; MacLean, L.; Irving, D.

    1989-05-01

    We conducted a 6-y follow-up study that included workers in an aluminum smelter in British Columbia. Of the original cohort, 951 workers left the industry and 985 workers participated in both studies. Comparison of those who left and those who remained showed that those who left were (1) older, (2) had a slightly higher prevalence of respiratory symptoms, and (3) had lower lung function; this was especially true for workers who were 50 + y of age at the time the initial study was conducted. Analyses were conducted only on 586 male workers who did not change their job location or smoking habits between the initial and the follow-up study. Potroom workers in the ''high-exposure'' group had a significant reduction in the prevalence of cough, but experienced an increase in the prevalence of wheeze. There was no significant difference in the annual decline in forced expiratory volume in 1 sec and forced vital capacity between the potroom workers and controls. In general, older workers and smokers had a greater decline in lung function compared to younger workers and nonsmokers. Leukocyte count done during the initial study was found to be an independent predictor of longitudinal decline in lung function. The lack of exposure effect on longitudinal decline in lung function could be due to ''healthy worker'' effect and improvement in the working condition of the smelter.

  6. Sleep and the Transition to Adolescence: A Longitudinal Study

    PubMed Central

    Sadeh, Avi; Dahl, Ronald E.; Shahar, Golan; Rosenblat-Stein, Shiran

    2009-01-01

    Study Objectives: To assess the links between sleep and pubertal development using a longitudinal design. Design: Three consecutive annual assessments of sleep and pubertal development. Sleep was assessed using a week of home actigraphy. Setting: Naturalistic sleep in the home setting of school children, Tel Aviv Area, Israel. Participants: A sample of 94 (41 boys) typically developing healthy school-age children (age range at first assessment: 9.9–11.2 years). Intervention: N/A Measurements and Results: The Petersen's Pubertal Development Scale (PDS) and Sexual Maturation Scale (SMS) were used to assess pubertal development, and a week of actigraphy served to assess naturalistic sleep patterns. The results reflect expected developmental trends: an increase in signs of pubertal maturation, delayed sleep onset, and shorter sleep time. After controlling for age, significant relationships were found between sleep onset time, true sleep time, and number of night wakings at Time 1 and pubertal ratings at Time 2, and pubertal changes from Time 1 to Time 2. Delayed and disrupted sleep at Time 1 predicted faster pubertal changes from Time 1 to Time 2. These results were supported by structural equation modeling. These findings were similar in boys and girls. Conclusions: Based on these longitudinal data, it appears that pubertal changes in sleep (delayed sleep phase and disrupted sleep patterns) antedate bodily changes associated with puberty. The underlying mechanisms explaining these predictive links should be further explored. Citation: Sadeh A; Dahl RE; Shahar G; Rosenblat-Stein S. Sleep and the transition to adolescence: a longitudinal study. SLEEP 2009;32(12):1602-1609. PMID:20041596

  7. Source challenges resulting from the first applications of a UV storage ring FEL on Super-ACO

    NASA Astrophysics Data System (ADS)

    Couprie, M. E.; Bakker, R.; Garzella, D.; Nahn, L.; Marsi, M.; Mérola, F.; Hara, T.; Billardon, M.

    1996-02-01

    On the Super-ACO free electron laser were developed the first applications of a storage ring based FEL and of a UV FEL. The feasibility of use was demonstrated in 1993 with a time resolved polarised fluorescence experiment in biology. After these experiments, the stability of the laser source was significantly improved, with the installation of a longitudinal feedback. A particular advantage of a storage ring FEL source is to provide as well naturally synchronized synchrotron radiation. A first pump-probe time-resolved experiment coupling such two tunable, synchronized light sources was then performed in surface physics.

  8. Histo-topographic study of the longitudinal anal muscle.

    PubMed

    Macchi, Veronica; Porzionato, Andrea; Stecco, Carla; Vigato, Enrico; Parenti, Anna; De Caro, Raffaele

    2008-07-01

    The longitudinal anal muscle (LAM) has been described as a vertical layer of muscular tissue interposed between the circular layers of the internal (IAS) and external (EAS) anal sphincters. There is, however, no general agreement in the literature on its composition and attachments. The aim of this study was to investigate the histological structure, attachments, and topography of the LAM in order to evaluate its role in continence and defecation, thus enhancing knowledge of the surgical anatomy of this region. After in situ formalin fixation, the pelvic viscera were removed from eight male and eight female cadavers (age range: 52-72 years). Serial macrosections of the bladder base, lower rectum and anal canal, cervix and pelvic floor complex, cut in the transverse (six specimens) and coronal (six specimens) planes, underwent histological and immunohistochemical studies. Four specimens were studied using the E12 sheet plastination technique. The LAM was identified in 10/12 specimens (83%). Transverse and coronal sections made clear that it is a longitudinal layer of muscular tissue, marking the boundary between the internal and external anal sphincters. From the anorectal junction it extends along the anal canal, receives fibers from the innermost part of the puborectalis and the puboanalis muscles, and terminates with seven to nine fibro-elastic septa, which traverse the subcutaneous part of the external anal sphincter, reaching the perianal dermis. In the transverse plane, the mean thickness of the LAM was 1.68 +/- 0.27 mm. Immunohistochemical staining showed that the LAM consists of predominantly outer striated muscle fibers and smaller numbers of inner smooth muscle fibers, respectively coming from the levator ani muscle and from the longitudinal muscular layer of the rectum. The oblique fibers suggest that the LAM may represent the intermediate longitudinal course of small bridging muscle bundles going reciprocally from the striated EAS to the smooth IAS and

  9. Design and methods of the national Vietnam veterans longitudinal study.

    PubMed

    Schlenger, William E; Corry, Nida H; Kulka, Richard A; Williams, Christianna S; Henn-Haase, Clare; Marmar, Charles R

    2015-09-01

    The National Vietnam Veterans Longitudinal Study (NVVLS) is the second assessment of a representative cohort of US veterans who served during the Vietnam War era, either in Vietnam or elsewhere. The cohort was initially surveyed in the National Vietnam Veterans Readjustment Study (NVVRS) from 1984 to 1988 to assess the prevalence, incidence, and effects of post-traumatic stress disorder (PTSD) and other post-war problems. The NVVLS sought to re-interview the cohort to assess the long-term course of PTSD. NVVLS data collection began July 3, 2012 and ended May 17, 2013, comprising three components: a mailed health questionnaire, a telephone health survey interview, and, for a probability sample of theater Veterans, a clinical diagnostic telephone interview administered by licensed psychologists. Excluding decedents, 78.8% completed the questionnaire and/or telephone survey, and 55.0% of selected living veterans participated in the clinical interview. This report provides a description of the NVVLS design and methods. Together, the NVVRS and NVVLS constitute a nationally representative longitudinal study of Vietnam veterans, and extend the NVVRS as a critical resource for scientific and policy analyses for Vietnam veterans, with policy relevance for Iraq and Afghanistan veterans. PMID:26096554

  10. High harmonic generation in undulators for FEL

    NASA Astrophysics Data System (ADS)

    Zhukovsky, K.

    2016-02-01

    The analytical study of the undulator radiation (UR), accounting for major sources of the spectral line broadening is presented. Analytical expressions for the UR spectrum and intensity are obtained. They demonstrate possibilities of the compensation of the divergency by the constant magnetic component. Some examples of single and double frequency undulators are considered. Generation of harmonics is studied with account for homogeneous and inhomogeneous broadening in real devices. The obtained results with account for all broadening sources are applied for evaluation of free electron laser (FEL) performance and compared with those, obtained with the ideal undulator.

  11. "Old Age and Loneliness: Cross-Sectional and Longitudinal Analyses in the Tampere Longitudinal Study on Aging"

    ERIC Educational Resources Information Center

    Jylha, Marja

    2004-01-01

    The purpose of this study was to examine whether older age is associated with increasing loneliness in people aged 60 and over. Data came from TamELSA, a population-based prospective longitudinal study in Tampere, Finland. The followup time was 20 years. Loneliness was measured by a single question--"Do you feel lonely?"--with the possible answers…

  12. A longitudinal study of epigenetic variation in twins

    PubMed Central

    Caspi, Avshalom; Williams, Benjamin; Craig, Ian W; Houts, Renate; Ambler, Antony; Moffitt, Terrie E; Mill, Jonathan

    2010-01-01

    DNA methylation is a key epigenetic mechanism involved in the developmental regulation of gene expression. Alterations in DNA methylation are established contributors to inter-individual phenotypic variation and have been associated with disease susceptibility. The degree to which changes in loci-specific DNA methylation are under the influence of heritable and environmental factors is largely unknown. In this study, we quantitatively measured DNA methylation across the promoter regions of the dopamine receptor 4 gene (DRD4), the serotonin transporter gene (SLC6A4/SERT) and the X-linked monoamine oxidase A gene (MAOA) using DNA sampled at both ages 5 and 10 years in 46 MZ twinpairs and 45 DZ twin-pairs (total n = 182). Our data suggest that DNA methylation differences are apparent already in early childhood, even between genetically identical individuals, and that individual differences in methylation are not stable over time. Our longitudinal-developmental study suggests that environmental influences are important factors accounting for interindividual DNA methylation differences, and that these influences differ across the genome. The observation of dynamic changes in DNA methylation over time highlights the importance of longitudinal research designs for epigenetic research. PMID:20505345

  13. Maintaining Superior Follow-Up Rates in a Longitudinal Study: Experiences from the College Life Study

    PubMed Central

    Vincent, Kathryn B.; Kasperski, Sarah J.; Caldeira, Kimberly M.; Garnier-Dykstra, Laura M.; Pinchevsky, Gillian M.; O’Grady, Kevin E.; Arria, Amelia M.

    2011-01-01

    Longitudinal studies are often considered to be a gold standard for research, but the operational management of such studies is not often discussed in detail; this paper describes strategies used to track and maintain high levels of participation in a longitudinal study involving annual personal interviews with a cohort of 1,253 undergraduates (first-time, first-year students at time of enrollment) at a large public mid-Atlantic university. PMID:22247739

  14. Optimization of precursor synthesis, formulation and stability of 1′-[18 F] fluoroethyl-β-d-lactose ([18 F]FEL) for preclinical studies in detection of pancreatic cancer

    PubMed Central

    Paolillo, Vincenzo; De Palatis, Louis; Alauddin, Mian M.

    2014-01-01

    Introduction 1′-[18 F]Fluoroethyl-β-d-lactose ([18 F]FEL) is a new PET imaging agent for early detection of pancreatic cancer and hepatocellular carcinoma. We previously reported the syntheses of [18 F]FEL using a bromo- and a tosyl- precursor, followed by an improved method using a nosyl-precursor. However, some steps in the synthesis of the precursor appeared to be problematic producing low yields. Here, we report on an optimized method for synthesis of the precursor and production of [18 F]FEL; we also describe [18 F]FEL’s formulation and stability. Methods Acetylation of d-lactose 1 was performed following a literature procedure to obtain 1′,2′,3′,6′,2,3,4,6-d-lactose octa-acetate 2a/2b. Bromination of 2a/2b was performed using HBr/acetic acid to produce 1'-bromo-2′,3′,6′,2,3,4,6-hepta-O-acetyl-α-d-lactose 3. Coupling of 3 with ethylene glycol was performed in the presence of Ag-tosylate and an excess of ethylene glycol to produce 4a. Compound 4a was reacted with p-nitrophenylsulfonyl chloride to produce the nosyl derivative 5. Radiofluorination of 5 was performed using K[18 F]fluoride/kryptofix to obtain 6, which was purified by HPLC and hydrolyzed with Na-methoxide to produce 7. Results Compound 2 (2a/2b) was obtained in 83% yield as a mixture of two anomeric products. Compound 3 was obtained from the 2a/2b mixture in 80% yield as one product. Coupling of 3 with ethylene glycol produced 4a in 90% yield. Compound 5 was obtained in 64% yield, and radiofluorination of 5 produced 6 in 62.5% ± 7.5% yields (n = 8). Hydrolysis of 6 with Na-methoxide produced 7 in 42.0% ± 7.0% yield (n = 8) from the end of bombardment. Conclusions A simple 4-step synthesis of the precursor, compound 5, has been achieved with improved yields. A new formulation of [18 F]FEL has been developed that allows the product to remain stable at ambient temperature for use in animal studies. This improved synthesis of the precursor and stable formulation of [18 F]FEL should

  15. A Parameter Optimization for a National SASE FEL Facility

    SciTech Connect

    Yavas, O.; Yigit, S.

    2007-04-23

    The parameter optimization for a national SASE FEL facility was studied. Turkish State Planing Organization (DPT) gave financial support as an inter-universities project to begin technical design studies and test facility of National Accelerator Complex starting from 2006. In addition to a particle factory, the complex will contain a linac based free electron laser, positron ring based synchrotron radiation facilities and a proton accelerator. In this paper, we have given some results of main parameters of SASE FEL facility based on 130 MeV linac, application potential in basic and applied research.

  16. Optimisation of An HHG-Seeded Harmonic Cascade FEL Design for the NLS Project

    SciTech Connect

    Dunning, David; Thompson, Neil; Bartolini, Riccardo; Geng, Huiping; Huang, Zhirong; McNeil, Brian; /Strathclyde U.

    2012-06-25

    Optimization studies of an HHG-seeded harmonic cascade FEL design for the UK's proposed New Light Source (NLS) facility are presented. Three separate FELs are planned to meet the requirements for continuous coverage of the photon energy range 50-1000 eV with variable polarization, 20 fs pulse widths and good temporal coherence. The design uses an HHG seed source tuneable from 50-100 eV to provide direct FEL seeding in this range, and one or two stage harmonic cascades to reach the higher photon energies. Studies have been carried out to optimize a harmonic cascade FEL operating at 1 keV; topics investigated include modulator configuration, seed power level and ef- fects of the HHG seed structure. FEL simulations using realistic electron beam distributions are presented and tolerance to increased emittance has been considered.

  17. Longitudinal bunch dynamics study with coherent synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Billinghurst, B. E.; Bergstrom, J. C.; Baribeau, C.; Batten, T.; May, T. E.; Vogt, J. M.; Wurtz, W. A.

    2016-02-01

    An electron bunch circulating in a storage ring constitutes a dynamical system with both longitudinal and transverse degrees of freedom. Through a self-interaction with the wakefields created by the bunch, certain of these degrees may get excited, defining a set of eigenmodes analogous to a spectroscopic series. The present study focuses on the longitudinal modes of a single bunch. The excitation of a mode appears as an amplitude modulation at the mode frequency of the coherent synchrotron radiation (CSR) emitted by the bunch. The modulations are superimposed on a much larger continuum from CSR emission in the continuous mode. A given eigenmode is classified by the integer m which is the ratio of the mode frequency to the synchrotron frequency. The present measurements extend up to m =8 and focus on the region near the instability thresholds. At threshold the modes are excited sequentially, resembling a staircase when the mode frequencies are plotted as a function of bunch length or synchrotron frequency. Adjacent modes are observed to coexist at the boundaries between the modes. An energy-independent correlation is observed between the threshold current for an instability and the corresponding zero-current bunch length. Measurements were made at five beam energies between 1.0 and 2.9 GeV at the Canadian Light Source. The CSR was measured in the time domain using an unbiased Schottky diode spanning 50-75 GHz.

  18. Longitudinal Study: Efficacy of Online Technology Tools for Instructional Use

    NASA Technical Reports Server (NTRS)

    Uenking, Michael D.

    2011-01-01

    Studies show that the student population (secondary and post secondary) is becoming increasingly more technologically savvy. Use of the internet, computers, MP3 players, and other technologies along with online gaming has increased tremendously amongst this population such that it is creating an apparent paradigm shift in the learning modalities of these students. Instructors and facilitators of learning can no longer rely solely on traditional lecture-based lesson formals. In order to achieve student academic success and satisfaction and to increase student retention, instructors must embrace various technology tools that are available and employ them in their lessons. A longitudinal study (January 2009-June 2010) has been performed that encompasses the use of several technology tools in an instructional setting. The study provides further evidence that students not only like the tools that are being used, but prefer that these tools be used to help supplement and enhance instruction.

  19. A Longitudinal Examination of Childhood Maltreatment and Adolescent Obesity: Results from the National Longitudinal Study of Adolescent Health (AddHealth) Study

    ERIC Educational Resources Information Center

    Shin, Sunny Hyucksun; Miller, Daniel P.

    2012-01-01

    Objectives: We sought to explore the association between childhood maltreatment (e.g., neglect, physical and sexual abuse) and longitudinal growth trajectories of body mass index (BMI) from adolescence to young adulthood. Methods: We used latent curve modeling to examine data from the National Longitudinal Study of Adolescent Health (N = 8,471),…

  20. FERMI@Elettra FEL Design Technical Optimization Final Report

    SciTech Connect

    Fawley, William; Penn, Gregory; Allaria, Enrico; De Ninno,Giovanni; Graves, William

    2006-07-31

    This is the final report of the FEL Design Group for the Technical Optimization Study for the FERMI{at}ELETTRA project. The FERMI{at}ELETTRA project is based on the principle of harmonic upshifting of an initial ''seed'' signal in a single pass, FEL amplifier employing multiple undulators. There are a number of FEL physics principles which underlie this approach to obtaining short wavelength output: (1) the energy modulation of the electron beam via the resonant interaction with an external laser seed (2) the use of a chromatic dispersive section to then develop a strong density modulation with large harmonic overtones (3) the production of coherent radiation by the microbunched beam in a downstream radiator. Within the context of the FERMI project, we discuss each of these elements in turn.

  1. Status report on the development of a high-power UV/IR FEL at CEBAF

    SciTech Connect

    Benson, S.; Bohn, C.; Dylla, H.F.

    1995-12-31

    Last year we presented a design for a kilowatt industrial UV FEL based on a superconducting RF accelerator delivering 5 mA of electron-beam current at 200 MeV with energy recovery to enhance efficiency. Since then, we have progressed toward resolving several issues associated with that design. More exact simulations of the injector have resulted in a more accurate estimate of the injector performance. A new injection method has reduced the longitudinal and transverse emittance at the linac entrance. A more compact lattice has been designed for the UV FEL, and a new recirculation scheme has been identified which greatly increases the threshold for longitudinal instabilities. We decided to use a wiggler from the Advanced Photon Source which leads to a robust high-gain FEL. Analysis of the stability of an RF control system based on CEBAF control modules indicates that only minor modifications will be needed to apply them to this FEL. Detailed magnet specifications, vacuum-chamber beam apertures, and diagnostic specifications have been developed for the recirculation arcs. The design of the optical cavity has been conceptualized, and control systems have been devised to regulate mirror distortion. A half-scale model of one of the end-corner cubes has been built and tested. Finally, three-dimensional simulations have been carried out which indicate that the FEL should exceed its minimum design goals with adequate performance margin.

  2. Free-electron-laser (FEL)-induced desorption of ions from tooth dentine

    NASA Astrophysics Data System (ADS)

    Ogino, Seiji; Awazu, Kunio; Tomimasu, Takio

    1997-05-01

    Free electron laser (FEL) with the wide wavelength tunability has been developed and used for various applications. The FEL gives high efficiency for the photo- induced ablation when the laser is tuned to an absorption maximum of the target. This study investigates the FEL induced desorption of ions from tooth dentine to find new possibility for laser dentistry. The FEL was tuned to 9.4 (Mu) m, which is an absorption maximum of phosphoric acid ion known as major component of dentine. The FEL pulse length was several ps. The output average power was varied from 5 to 20mW by filters. A time-of-flight mass spectroscopy systems were developed for the purpose of analyzing the desorbed ions of varying masses. After the 9.4 micrometers FEL irradiation, the dentine surface was ablated, and visible light emission was observed. As a result, positive ions which correspond to Na+ and many phosphoric acid ions were measured. The positive ions, however were not observed when the FEL was not tuned to the absorption peak of the target. Therefore, this wavelength dependence points to resonant multiphoton vibrational excitation of molecules by the 9.4 micrometers FEL irradiation.

  3. X-band prebunched FEL amplifier

    SciTech Connect

    Saito, Kazuyoshi; Takayama, Ken; Ozaki, Toshiyuki

    1995-12-31

    Following the successful results of the ion-channel-guiding FEL experiments, we began a new experiment {open_quotes}prebunched FEL{close_quotes}. It is an FEL driven by prebunched beams, whose configuration is a normal FEL system with a prebuncher like the bunching section of a klystron. There are two purposes in this prebunched FEL system; (1) Demonstration of a compact/efficient FEL. Attaining the saturation power level with a short wiggler length (compact wiggler) and enhancing the power through the remaining wiggler length by wiggler tapering (high efficiency FEL). (2) Experimental simulation of multi-stage FELs in the FEL-TBA. Examination of FEL interactions with prebunched injection beams, especially, about the controllability of the output RF phase by changing the RF phase of the input seed power to the wiggler. Recent experimental results show: (1) The saturation power of 120MW has been attained at the wiggler length of 1.1m by 1.5MeV prebunched beams with a 45%-modulated 750A current. However, enhanced power has not been observed yet by wiggler tapering. (2) The current modulation of the injection beam (1.5MeV-500A) becoming higher than 30%, the adjustable range of the output RF phase was limitted less than 40 degrees by the input power of 60kW only. Detail explanations of design concept, theoretical and experimental results will be presented at the conference.

  4. A longitudinal study of early intellectual development in hemiplegic children.

    PubMed

    Muter, V; Taylor, S; Vargha-Khadem, F

    1997-03-01

    Thirty-eight 3- to 5-year-old children with unilateral lesions sustained pre- or peri-natally were studied longitudinally over a 2-year period, and their IQ scores compared with those of 20 "medical' controls. The failure to discover laterality effects following early unilateral injury supports the hypothesis of at least broad functional equipotentiality. There were few decrements in intellectual functioning provided the injury was not accompanied by seizures. The presence of seizures in contrast had a deleterious effect on both verbal and nonverbal aspects of cognitive functioning. While the IQs of the hemiplegic groups showed considerable stability over the 2-year span of the study, there was evidence that performance IQ, even in seizure-free patients, might be selectively impaired because of competition within the intact neural space for the sparing of verbal IQ. PMID:9051677

  5. Semiparametric Stochastic Modeling of the Rate Function in Longitudinal Studies

    PubMed Central

    Zhu, Bin; Taylor, Jeremy M.G.; Song, Peter X.-K.

    2011-01-01

    In longitudinal biomedical studies, there is often interest in the rate functions, which describe the functional rates of change of biomarker profiles. This paper proposes a semiparametric approach to model these functions as the realizations of stochastic processes defined by stochastic differential equations. These processes are dependent on the covariates of interest and vary around a specified parametric function. An efficient Markov chain Monte Carlo algorithm is developed for inference. The proposed method is compared with several existing methods in terms of goodness-of-fit and more importantly the ability to forecast future functional data in a simulation study. The proposed methodology is applied to prostate-specific antigen profiles for illustration. Supplementary materials for this paper are available online. PMID:22423170

  6. Hearing loss in the Royal Norwegian Navy: A longitudinal study.

    PubMed

    Irgens-Hansen, Kaja; Baste, Valborg; Bråtveit, Magne; Lind, Ola; Koefoed, Vilhelm F; Moen, Bente E

    2016-01-01

    The aims of this longitudinal study were to investigate a significant threshold shift (STS) among personnel working on board the Royal Norwegian Navy's (RNoN) vessels between 2012 and 2014 and to identify possible determinants of STS. Hearing thresholds were measured by pure tone audiometry in two consecutive examinations (n = 226). STS was defined as an average change in hearing thresholds ≥ + 10 dB at 2,000 Hz, 3,000 Hz, and 4,000 Hz in either ear. Determinants of STS were assessed through a questionnaire. The incidence of STS was 23.0%. Significant determinants of STS were the number of episodes of temporary threshold shifts (TTS) in the Navy, exposure to continuous loud noise during work on board, and the number of gun shots (in the Navy, hunting, and sports). This study indicated a significant association between noise exposure on board Navy vessels and development of STS. PMID:27157689

  7. North American Prodrome Longitudinal Study (NAPLS 2): The Prodromal Symptoms

    PubMed Central

    Addington, Jean; Liu, Lu; Buchy, Lisa; Cadenhead, Kristin S.; Cannon, Tyrone D.; Cornblatt, Barbara A.; Perkins, Diana O.; Seidman, Larry J.; Tsuang, Ming T.; Walker, Elaine F.; Woods, Scott W.; Bearden, Carrie E.; Mathalon, Daniel H.; McGlashan, Thomas H.

    2015-01-01

    In studies describing the long-term follow-up up of youth at clinical high risk (CHR) of psychosis, little attention has been given to details of specific prodromal symptoms. In this paper we describe the prodromal symptoms of 764 CHR participants recruited in the multi-site North American Prodrome Longitudinal Study (NAPLS). Symptoms were rated on the Scale of Prodromal Symptoms (SOPS) at baseline and 6, 12, 18 and 24 month follow-ups. Clinical outcome at the 2-year assessment was categorized as psychotic, prodromal progression, symptomatic or in remission. The majority of the CHR sample (93%) met criteria for the attenuated positive symptoms syndrome (APSS). Significant improvements in SOPS symptoms were observed overtime. Unusual thought content, disorganized communication and overall ratings on disorganized symptoms differentiated those who transitioned to psychosis from the other clinical outcome groups. Suspiciousness and total positive symptoms differentiated those in remission from the other clinical outcome groups. PMID:25919383

  8. Hearing loss in the Royal Norwegian Navy: A longitudinal study

    PubMed Central

    Irgens-Hansen, Kaja; Baste, Valborg; Bråtveit, Magne; Lind, Ola; Koefoed, Vilhelm F.; Moen, Bente E

    2016-01-01

    The aims of this longitudinal study were to investigate a significant threshold shift (STS) among personnel working on board the Royal Norwegian Navy's (RNoN) vessels between 2012 and 2014 and to identify possible determinants of STS. Hearing thresholds were measured by pure tone audiometry in two consecutive examinations (n = 226). STS was defined as an average change in hearing thresholds ≥ + 10 dB at 2,000 Hz, 3,000 Hz, and 4,000 Hz in either ear. Determinants of STS were assessed through a questionnaire. The incidence of STS was 23.0%. Significant determinants of STS were the number of episodes of temporary threshold shifts (TTS) in the Navy, exposure to continuous loud noise during work on board, and the number of gun shots (in the Navy, hunting, and sports). This study indicated a significant association between noise exposure on board Navy vessels and development of STS. PMID:27157689

  9. A Longitudinal Adoption Study of Substance Use Behavior in Adolescence.

    PubMed

    Huibregtse, Brooke M; Corley, Robin P; Wadsworth, Sally J; Vandever, Joanna M; DeFries, John C; Stallings, Michael C

    2016-08-01

    Although cross-sectional twin studies have assessed the genetic and environmental etiologies of substance use during adolescence and early adulthood, comparisons of results across different samples, measures, and cohorts are problematic. While several longitudinal twin studies have investigated these issues, few corroborating adoption studies have been conducted. The current study is the first to estimate the magnitude of genetic, shared environmental, and non-shared environmental influences on substance use (cigarettes, alcohol, and marijuana) from ages 14 to 18 years, using a prospective longitudinal adoption design. Adoptive and control sibling correlations provided substantial evidence for early genetic effects on cigarette, alcohol, and marijuana use/no use. Shared environmental effects were relatively modest, except for alcohol use, which showed increases in late adolescence (age 17 to 18 years). Sibling similarity for quantity/frequency of use also support additive genetic influences across adolescence, with some shared environmental influences for all three substances. To test the stability of these influences across time, a series of independent pathway models were run to explore common and age-specific influences. For all substances, there were minimal age-specific additive genetic and shared environmental influences on quantity/frequency of use. Further, there was a trend toward increasing genetic influences on cigarette and alcohol use across ages. Genetic influences on marijuana were important early, but did not contribute substantially at age 17 and 18 years. Overall, the findings indicate that genetic influences make important contributions to the frequency/quantity of substance use in adolescence, and suggest that new genetic influences may emerge in late adolescence for cigarette and alcohol use. PMID:27161024

  10. A Longitudinal Study of Uremic Pruritus in Hemodialysis Patients

    PubMed Central

    Mathur, Vandana S.; Lindberg, Jill; Germain, Michael; Block, Geoffrey; Tumlin, James; Smith, Mark; Grewal, Mandeep

    2010-01-01

    Background and objectives: Although uremic pruritus (UP) is a highly prevalent complication of chronic kidney disease, it remains poorly characterized. There have been no longitudinal studies of natural history, and no health-related quality of life (HR-QOL) instruments have been developed for UP. The objectives of this study were to describe the natural history of UP, to compare rating scales of itching intensity, and to assess usefulness and validity of HR-QOL instruments for UP. Design, setting, participants, & measurements: The intensity, severity, and effects of pathologic itching on HR-QOL were assessed prospectively in 103 patients with UP on chronic hemodialysis. Outcome measures were obtained at scheduled intervals over 3.5 months. Results: Itching daily or nearly daily was reported by 84% of patients and had been ongoing for >1 year in 59%. In 83%, pruritus involved large, nondermatomal areas with striking bilateral symmetry. Two thirds of the patients were using medications such as antihistamines, steroids, and various emollients without satisfactory relief of itching. Statistically significant associations were found among itching intensity, severity, and HR-QOL measures in domains such as mood, social relations, and sleep. Among patients with moderate-to-severe UP, changes in itching intensity of 20% or greater were associated with significant reductions in HR-QOL measures. Conclusions: This first longitudinal study of UP describes key features of UP and its effect on HR-QOL. The assessment instruments we have developed are easily used, are responsive to changes in UP intensity, and should facilitate clinical evaluation and research to meet the needs of afflicted patients. PMID:20558560

  11. Nurses' ethical conflict with hospitals: a longitudinal study of outcomes.

    PubMed

    Gaudine, Alice; Thorne, Linda

    2012-11-01

    This study examined the association of nurses' ethical conflict with hospitals with organizational commitment, stress, turnover intention, absence and turnover. Participants were 410 nurses working at four different Canadian hospitals. A longitudinal design was used where nurses completed a questionnaire to capture ethical conflict, stress and organizational commitment, and one year later, measures of turnover intention, absence and actual turnover were obtained for the same sample. We found three aspects of nurses' ethical conflict with hospitals: patient care values, value of nurses, and staffing policy values. Our findings showed that all three aspects of nurses' ethical conflict are associated with stress and patient care values is associated with actual turnover. We also found that staffing policy values is predictive of turnover intention, and that patient care values is predictive of absenteeism. Thus, our findings show the multidimensionality of nurses' ethical conflict with hospitals. Further implications of our findings for practice and theory are discussed. PMID:22619238

  12. Motion sickness susceptibility and aerobic fitness: a longitudinal study.

    PubMed

    Cheung, B S; Money, K E; Jacobs, I

    1990-03-01

    A longitudinal study evaluated the susceptibility to motion sickness in initially unfit subjects before and after an endurance training program. Motion stimulation was provided by the Precision Angular Mover, in which the subject was tumbled head over heels about an Earth-horizontal axis at 20 cycles per minute in darkness. Maximal aerobic power and the blood lactate response to submaximal exercise were evaluated with cycle ergometry. The training program caused significant improvements in VO2max and endurance capacity, and a significant decrease in percent body fat. There was a significant (p less than 0.0125) increase in motion sickness susceptibility after the physical training, suggesting that increased physical fitness caused increased susceptibility to motion sickness in some individuals. PMID:2156490

  13. Early cognitive profiles of emergent readers: a longitudinal study.

    PubMed

    Brunswick, Nicola; Neil Martin, G; Rippon, Georgina

    2012-02-01

    This longitudinal study examined the contribution of phonological awareness, phonological memory, and visuospatial ability to reading development in 142 English-speaking children from the start of kindergarten to the middle of Grade 2. Partial cross-lagged analyses revealed significant relationships between early performance on block design and matching letter-like forms tasks and later reading ability. Rhyme awareness correlated with later reading ability during the earliest stages, but onset awareness did not emerge as important until after the children had started reading. Digit span correlated significantly with future reading ability at every stage. These findings indicate that although phonological awareness, phonological memory, and visuospatial ability are all necessary for emergent reading, their relative importance varies across the first 2 years of reading development. PMID:21962459

  14. Attachment orientations and depression: a longitudinal study of new parents.

    PubMed

    Rholes, W Steven; Simpson, Jeffry A; Kohn, Jamie L; Wilson, Carol L; Martin, A McLeish; Tran, Sisi; Kashy, Deborah A

    2011-04-01

    In this longitudinal study, we followed a large sample of first-time parents (both partners) across the first 2 years of the transition to parenthood. Guided by attachment theory (Bowlby, 1969), we tested several predictions about how attachment anxiety and avoidance are related to the incidence, maintenance, increase, and decline of depressive symptoms in both sexes across the first 2 years of the transition. We found that (a) the association between attachment anxiety and depressive symptoms was moderated by factors related to the marital and/or romantic relationship; (b) the association between avoidance and depressive symptoms was moderated by factors related to family responsibilities; (c) styles of caregiving provided by romantic partners affected depressive symptoms differently among anxious and avoidant persons; and (d) in certain predictable situations, depressive symptoms persisted at higher levels or increased to higher levels in anxious or avoidant persons across the 2-year transition period. Important implications of these results are discussed. PMID:21443372

  15. Young adults with developmental coordination disorder: a longitudinal study.

    PubMed

    Tal-Saban, Miri; Ornoy, Asher; Parush, Shula

    2014-01-01

    We conducted a longitudinal study to assess the continuing influence of developmental coordination disorder (DCD) on quality of life and participation. Ninety-six participants (25 in the DCD group, 30 in the borderline group, and 41 in the control group) ages 22-29 yr who had been screened for DCD 3-4 yr previously completed the Participation in Every Day Activities of Life, the Life-Satisfaction Questionnaire, and the World Health Organization Quality of Life (WHOQOL-BREF) instrument. Multivariate analysis of variance revealed a significant between-groups difference, F(7, 95) = 2.89, p = .001, η = 0.173, and post hoc analyses revealed that participants in the DCD and borderline groups scored lower overall on participation, quality of life, and life satisfaction. Linear regression found the Psychological Health domain of the WHOQOL-BREF to be a significant predictor of life satisfaction (B = 0.533; p = .001). PMID:24797194

  16. Facial expression recognition in Alzheimer's disease: a longitudinal study.

    PubMed

    Torres, Bianca; Santos, Raquel Luiza; Sousa, Maria Fernanda Barroso de; Simões Neto, José Pedro; Nogueira, Marcela Moreira Lima; Belfort, Tatiana T; Dias, Rachel; Dourado, Marcia Cristina Nascimento

    2015-05-01

    Facial recognition is one of the most important aspects of social cognition. In this study, we investigate the patterns of change and the factors involved in the ability to recognize emotion in mild Alzheimer's disease (AD). Through a longitudinal design, we assessed 30 people with AD. We used an experimental task that includes matching expressions with picture stimuli, labelling emotions and emotionally recognizing a stimulus situation. We observed a significant difference in the situational recognition task (p ≤ 0.05) between baseline and the second evaluation. The linear regression showed that cognition is a predictor of emotion recognition impairment (p ≤ 0.05). The ability to perceive emotions from facial expressions was impaired, particularly when the emotions presented were relatively subtle. Cognition is recruited to comprehend emotional situations in cases of mild dementia. PMID:26017202

  17. A Longitudinal Twin Study of Skewed X Chromosome-Inactivation

    PubMed Central

    Wong, Chloe Chung Yi; Caspi, Avshalom; Williams, Benjamin; Houts, Renate; Craig, Ian W.; Mill, Jonathan

    2011-01-01

    X-chromosome inactivation (XCI) is a pivotal epigenetic mechanism involved in the dosage compensation of X-linked genes between males and females. In any given cell, the process of XCI in early female development is thought to be random across alleles and clonally maintained once established. Recent studies, however, suggest that XCI might not always be random and that skewed inactivation may become more prevalent with age. The factors influencing such XCI skewing and its changes over time are largely unknown. To elucidate the influence of stochastic, heritable and environmental factors in longitudinal changes in XCI, we examined X inactivation profiles in a sample of monozygotic (MZ) (n = 23) and dizygotic (DZ) (n = 22) female twin-pairs at ages 5 and 10 years. Compared to MZ twins who were highly concordant for allelic XCI ratios, DZ twins showed much lower levels of concordance. Whilst XCI patterns were moderately stable between ages 5 and 10 years, there was some drift over time with an increased prevalence of more extreme XCI skewing at age 10. To our knowledge, this study represents the earliest longitudinal assessment of skewed XCI patterns, and suggests that skewed XCI may already be established in early childhood. Our data also suggest a link between MZ twinning and the establishment of allelic XCI ratios, and demonstrate that acquired skewing in XCI after establishment is primarily mediated by stochastic mechanisms. These data have implications for our understanding about sex differences in complex disease, and the potential causes of phenotypic discordance between MZ female twins. PMID:21445353

  18. Saturation Measurements of a Visible SASE FEL

    SciTech Connect

    Carr, Roger

    2002-08-14

    VISA (Visible to Infrared SASE Amplifier) is an FEL designed to obtain high gain at a radiation wavelength of 800 nm. Large gain is achieved by driving the FEL with the 71 MeV, high brightness beam of the Accelerator Test Facility (ATF) and using a novel, strong focusing, 4 m long undulator with a gap of 6 mm and a period of 1.8 cm. We report measurements of exponential gain, saturation, and spectra of the FEL radiation intensity.

  19. Saturation Measurements of a Visible SASE FEL

    NASA Astrophysics Data System (ADS)

    Tremaine, A.; Frigola, P.; Murokh, A.; Pellegrini, C.; Reiche, S.

    2002-08-01

    VISA (Visible to Infrared SASE Amplifier) is an FEL designed to obtain high gain at a radiation wavelength of 800 nm. Large gain is achieved by driving the FEL with the 71 MeV, high brightness beam of the Accelerator Test Facility (ATF) and using a novel, strong focusing, 4m long undulator with a gap of 6 mm and a period of 1.8 cm. We report measurements of exponential gain, saturation, and spectra of the FEL radiation intensity.

  20. Assessing candidate serum biomarkers for Alzheimer's disease: a longitudinal study.

    PubMed

    Zabel, Matthew; Schrag, Matthew; Mueller, Claudius; Zhou, Weidong; Crofton, Andrew; Petersen, Floyd; Dickson, April; Kirsch, Wolff M

    2012-01-01

    Because of the growing impact of late onset cognitive loss, considerable effort has been directed toward the development of improved diagnostic techniques for Alzheimer's disease (AD) that may pave the way for earlier (and more effective) therapeutic efforts. Serum-based biomarkers are the least expensive and invasive modality for screening and routine monitoring. We systematically reviewed the literature to assemble a list of serum biomarkers relevant to AD. In parallel, we conducted a proteomic LC-MS/MS analysis of serum collected from neurologically normal subjects and subjects with mild cognitive impairment (MCI) and early AD (n = 6 in all). Complement C3 and alpha-2-macroglobulin were identified from both the literature review and our proteomic screen for further validation. For these two candidates, ELISA was performed on serum collected from a small independent cohort of subjects for longitudinal analysis. Serum was serially collected from neurologically normal subjects (n = 5) and subjects with MCI who were subsequently followed for a period of two years (n = 5) and regrouped into stable MCI and progressive MCI or AD (n = 6). The ability of each marker to predict which subjects with MCI would progress to dementia and which would remain cognitively stable was assessed. Patients with probable cerebral amyloid angiopathy were also identified (n = 3). This preliminary analysis tested the most-promising serum protein biomarkers for AD and we concluded that none are yet ready for use in the clinical diagnosis and management of dementia. However, a more thorough assessment in longitudinal studies with higher statistical power is warranted. PMID:22426016

  1. Prospects for the FEL (Free Electron Laser)

    SciTech Connect

    Sessler, A.M.

    1989-04-01

    The future for FELs depends upon the very large number of applications which is envisioned for them. These grow out of the FEL extensive range of wavelengths, tunability, and high power capability. High power requires demonstration of optical guiding. Tunability has already been demonstrated. And the effort to extend the range of wavelengths is ever ongoing. The future will also bring more work on gas-loaded FELs, on electromagnetic wigglers, and on harmonic generation. We can, also, look forward to observation of various new effects, a few of which will be described. Finally, a list of various FEL projects around the world will be given. 12 refs., 5 figs., 8 tabs.

  2. Optimal designs for epidemiologic longitudinal studies with binary outcomes.

    PubMed

    Mehtälä, Juha; Auranen, Kari; Kulathinal, Sangita

    2015-12-01

    Alternating presence and absence of a medical condition in human subjects is often modelled as an outcome of underlying process dynamics. Longitudinal studies provide important insights into research questions involving such dynamics. This article concerns optimal designs for studies in which the dynamics are modelled as a binary continuous-time Markov process. Either one or both the transition rate parameters in the model are to be estimated with maximum precision from a sequence of observations made at discrete times on a number of subjects. The design questions concern the choice of time interval between observations, the initial state of each subject and the choice between number of subjects versus repeated observations per subject. Sequential designs are considered due to dependence of the designs on the model parameters. The optimal time spacing can be approximated by the reciprocal of the sum of the two rates. The initial distribution of the study subjects should be taken into account when relatively few repeated samples per subject are to be collected. A study with a reasonably large size should be designed in more than one phase because there are then enough observations to be spent in the first phase to revise the time spacing for the subsequent phases. PMID:22170892

  3. Natural history of alpha mannosidosis a longitudinal study

    PubMed Central

    2013-01-01

    Background Alpha-Mannosidosis is a rare lysosomal storage disorder, caused by the deficiency of the enzyme alpha-Mannosidase. Clinically it is characterized by hearing impairment, skeletal and neurological abnormalities and mental retardation. In order to characterize the clinical features and disease progression of patients affected by alpha-Mannosidosis, a survey study was conducted. 43 patients from 4 European countries participated in this longitudinal study. Age range of the participants was 3 to 42 years. For each patient a medical history, complete physical and neurological examination, joint range of motion and assessment of physical endurance and of lung function were completed. In addition, serum and urinary oligosaccharide levels were analysed. Methods In this multicenter longitudinal study clinical data of 43 alpha-Mannosidosis patients were collected. In addition to objective clinical measurements biochemical assays were performed. Results Data analysis revealed a wide spectrum of clinical presentation regarding the severity and disease progression. Most clinical abnormalities were observed in the musculoskeletal and neurological system. All patients showed mental retardation and hearing loss from early childhood. An impairment in physical endurance was revealed by the 6-minute walk and 3-minute stair stair climb tests. There was only slight progression of a few clinical findings: Psychiatric troubles in both groups essentially, and respiratory dysfunction under 18 years. The serum and urinary oligosaccharide levels were increased in all affected individuals and correlated well with the 6-minute walk and 3-minute stair climb test results. Conclusions This study confirms that alpha-Mannosidosis is a very heterogeneous disorder regarding both, disease severity and progression. As it has been shown that Mannosidosis patients are able to perform lung function tests and the 6MWT and stair-climb test, these clinical parameters apparently can be used as

  4. Connections between Learning Experience, Study Behaviour and Academic Performance: A Longitudinal Study

    ERIC Educational Resources Information Center

    Ning, H. K.; Downing, Kevin

    2010-01-01

    Background: Whilst past studies have established the joint influence of student learning experience and study behaviour on academic achievement, few attempts have been made to determine their causal ordering in a longitudinal framework. Purpose: This study explored the reciprocal relationship between learning experience and study behaviour, and…

  5. Stress Process of Illicit Drug Use among U.S. Immigrants' Adolescent Children: A Longitudinal Study

    ERIC Educational Resources Information Center

    Choo, Hyekyung

    2012-01-01

    This study examined a full path model of stress process for predicting illicit drug use among Asian and Latino immigrants' adolescent children. Using 2-year longitudinal data (National Longitudinal Study of Adolescent Health) from a sample of adolescents with Asian or Latino immigrant parents (N = 2,353), the study explored structural…

  6. Parental influences on adolescent physical activity: a longitudinal study

    PubMed Central

    Ornelas, India J; Perreira, Krista M; Ayala, Guadalupe X

    2007-01-01

    Background Physical inactivity is increasing among adolescents in the U.S., especially among girls. Despite growing evidence that parents are an important influence on adolescent health, few longitudinal studies have explored the causal relationship between parental influence and physical activity. This study examines how the relationships between parental influences and adolescent physical activity differ by gender and tests whether these relationships are mediated by adolescents' self-esteem and depression. Methods Data are from the National Longitudinal Study of Adolescent Health. The sample includes 13,246 youth, grades 7 to 12, interviewed in 1995 and again 1 year later. Logit models were used to evaluate parental influences on achieving five or more bouts of moderate to vigorous physical activity per week [MVPA] and whether the relationship between parental influence and MVPA was mediated by adolescents' level of self-esteem and depression. Results Family cohesion, parent-child communication and parental engagement positively predicted MVPA for both genders one year later (odds ratios and 95% confidence intervals for females, 1.09 [1.05–1.12], 1.13 [1.07–1.19], 1.25 [1.17–1.33] and males, 1.08 [1.04–1.11], 1.14 [1.07–1.23], 1.23 [1.14–1.33], respectively); however, parental monitoring did not (odds ratio and confidence intervals for females and males, 1.02 [.97–1.07]). For both females and males, self-esteem mediated the relationship between parental influence and physical activity. Depressive symptoms were only a mediator among males. Females reported higher levels of parent-child communication and lower family cohesion compared with males. There were no gender differences in levels of parental monitoring and engagement. Females had significantly lower levels of self-esteem and higher levels of depressive symptoms than males. Conclusion Strategies to promote physical activity among adolescents should focus on increasing levels of family

  7. Undergraduate nursing students' learning styles: a longitudinal study.

    PubMed

    Fleming, Sandra; McKee, Gabrielle; Huntley-Moore, Sylvia

    2011-07-01

    This paper reports on the main findings of a longitudinal study of the learning styles of one cohort of undergraduate pre-registration nursing students at an Irish university. The Honey and Mumford (2000a) Learning Styles Questionnaire was administered to a sample of students in their first (n=202) and final year of study (n=166), the final sample number (58) was based on matched pairs. The most common dominant learning style in first year was the dual learning category (35%) while a large proportion of the students (53%) in their final year had no dominant learning style. The preferred learning style of students in their first (69%) and final (57%) year was reflector. Learning styles were significantly different at the two time points and there was a significant relationship between some learning styles and students' age but not with academic achievement. Total scores of all learning styles showed significant improvements across the two time points of the study. An important implication for nurse education practice is the need for nurse educators to be aware of students' learning styles and in an attempt to maximise students' learning potential, utilise a range of teaching and learning methodologies and assessments that develop all learning styles. PMID:20863600

  8. A longitudinal study relating carpeting with sick building syndrome

    SciTech Connect

    Norbaeck, D.; Torgen, M. )

    1989-01-01

    A longitudinal questionnaire study was performed among personnel in two Swedish primary schools with wall-to-wall carpets and four schools with hard floor covering. The study groups consisted of all primary schools equipped with wall-to-wall carpets in the town of Uppsala, plus a random sample of two newer and two elderly primary schools with hard floor covering. In an initial cross-sectional study, the wall-to-wall carpet group reported an enhanced prevalence of eye and airway symptoms, face rashes, headache, abnormal tiredness and a sensation of being electrostatically charged in comparison with personnel in schools with hard floor covering. Since the enhanced prevalence of symptoms in the wall-to-wall carpets versus the hard floor covering group was also observed among persons without signs of atopy it was concluded that wall-to-wall carpets are not exclusively a problem for the sensitive atopic individual. The type of ventilation system (mechanical ventilation versus natural ventilation) had no significant effect on the symptom frequencies. After the removal of the wall-to-wall carpets, many of the reported symptoms decreased to a level similar to the group without previous or present exposure to such carpets. However, the frequency of airway symptoms remained enhanced among the wall-to-wall carpet group.

  9. Short wavelength FELs using the SLAC linac

    NASA Astrophysics Data System (ADS)

    Winick, H.; Bane, K.; Boyce, R.; Cobb, J.; Loew, G.; Morton, P.; Nuhn, H.-D.; Paterson, J.; Pianetta, P.; Raubenheimer, T.; Seeman, J.; Tatchyn, R.; Vylet, V.; Pellegrini, C.; Rosenzweig, J.; Travish, G.; Prosnitz, D.; Scharlemann, E. T.; Halbach, K.; Kim, K.-J.; Schlueter, R.; Xie, M.; Bonifacio, R.; De Salvo, L.; Pierini, P.

    1994-08-01

    Recent technological developments have opened the possibility to construct a device which we call a linac coherent light source (LCLS) (C. Pellegrini et al., Nucl. Instr. and Meth. A 331 (1993) 223; H. Winick et al., Proc. IEEE 1993 Particle Accelerator Conf., Washington, DC, May 1993; C. Pellegrini, Nucl. Instr. and Meth. A 341 (1994) 326; J. Seeman, SPIE Meet. on Electron Beam Sources of High Brightness Radiation, San Diego, CA, July 1993 [1-4]); it would be a fourth-generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much shorter wavelength than the 240 nm that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3 to 100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high-energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low-gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by self-amplified-spontaneous-emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops (M. Cornacchia and H. Winick (eds.), SLAC Report 92/02; I. Ben-Zvi and H. Winick (eds.), BNL report 49651 [5,6]). The required low-emittance electron beam can be achieved with recently-developed rf photocathode electron guns (B.E. Carlsten, Nucl. Instr. and Meth. A 285 (1989) 313; J. Rosenzweig and L. Serafini, Proc. IEEE 1993 Particle Accelerator Conf., Washington, DC, 1993 [7,8]). The peak current is increased by about an

  10. Design study of a G-band FEL amplifier for application to cyclotron resonant heating in magnetic fusion reactors

    NASA Astrophysics Data System (ADS)

    Freund, H. P.; Read, M. E.; Jackson, R. H.; Pershing, D. E.; Taccetti, J. M.

    1995-04-01

    A G-band (140-150 GHz) free-electron laser is described using a coaxial hybrid iron (CHI) wiggler. The CHI wiggler is produced by insertion into a solenoid of a central rod and an outer ring composed of alternating ferrite and nonferrite spacers. The position of the spacers is such that the ferrite (nonferrite) spacers on the central rod are opposite the nonferrite (ferrite) spacers on the outer ring. The field is cylindrically symmetric and exhibits minima in the center of the gap providing for enhanced beam focusing. We describe a tapered wiggler amplifier for plasma heating applications. Preliminary design studies using a nonlinear simulation indicates that output powers of 3.5 MW are possible using a 690 kV/40 A electron beam for a total efficiency of 13%. It is important to note that no beam loss was observed even for realistic values of beam energy spread.

  11. A Dynamic Feedback Model for High Repetition Rate LINAC-Driven FELS

    SciTech Connect

    Mellado Munoz, M.; Doolittle, L.; Emma, P.; Huang, G.; Ratti, A.; Serrano, C.; Byrd, J. M.

    2012-05-20

    One of the concepts for the next generation of linacdriven FELs is a CW superconducting linac driving an electron beam with MHz repetition rates. One of the challenges for next generation FELs is improve the stability of the xray pulses by improving the shot-to-shot stability of the energy, charge, peak current, and timing jitter of the electron beam. A high repetition rate FEL with a CW linac presents an opportunity to use a variety of broadband feedbacks to stabilize the beam parameters. To understand the performance of such a feedback system, we are developing a dynamic model of the machine with a focus on the longitudinal beam properties. The model is being developed as an extension of the LITrack code and includes the dynamics of the beam-cavity interaction, RF feedback, beam-based feedback, and multibunch effects. In this paper, we present a detailed description of this model.

  12. A longitudinal study of maternal attachment and infant developmental outcomes

    PubMed Central

    Alhusen, Jeanne L.; Hayat, Matthew J.; Gross, Deborah

    2013-01-01

    Extant research has demonstrated that compared to adults with insecure attachment styles, more securely attached parents tend to be more responsive, sensitive, and involved parents resulting in improved outcomes for their children. Less studied is the influence of a mother's attachment style on her attachment to her unborn child during pregnancy and the consequent developmental outcomes of the child during early childhood. Thus, the aim of this prospective longitudinal study was to examine the relationship between maternal-fetal attachment (MFA) during pregnancy and infant and toddler outcomes and the role of mothers’ attachment style on early childhood developmental outcomes in an economically disadvantaged sample of women and their children. Gamma regression modeling demonstrated an avoidant maternal attachment style (b = .98, 95% CI [.97, .98], p < 0.001) and post-partum depressive symptomatology (b = .97, 95% CI [.96-.99], p = .03) were significant predictors of early childhood development. Women demonstrating higher avoidant attachment styles and greater depressive symptomatology were more likely to have children demonstrating early childhood developmental delays than those women with less avoidant attachment styles and less depressive symptomatology. Furthermore, women reporting higher MFA during pregnancy had more secure attachment styles and their children had more optimal early childhood development than those women reporting lower MFA and less secure attachment styles. Findings have implications for enhancing early intervention programs aimed at improving maternal and childhood outcomes. An earlier identification of disruptions in attachment may be beneficial in tailoring interventions focused on the mother-child dyad. PMID:23737011

  13. A longitudinal study of children exposed to sulfur oxides.

    PubMed

    Dodge, R; Solomon, P; Moyers, J; Hayes, C

    1985-05-01

    This study is a longitudinal comparison of the health of children exposed to markedly different concentrations of sulfur dioxide (SO2) and moderately different concentrations of particulate sulfate (SO4=). The four groups of subjects lived in two areas of one smelter town and in two other towns, one of which was also a smelter town. In the area of highest pollution, children were intermittently exposed to high SO2 levels (peak three-hour average concentration exceeded 2,500 micrograms/m3) and moderate particulate SO4= levels (average concentration was 10.1 micrograms/m3). When the children were grouped by the four gradients of pollution observed, the prevalence of cough (measured by questionnaire) correlated significantly with pollution levels (trend chi-square = 5.6, p = 0.02). No significant differences in the incidence of cough or other symptoms occurred among the groups of subjects over three years, and pulmonary function and lung function growth over the study were roughly equal among all the groups. These results suggest that intermittent elevations in SO2 concentration, in the presence of moderate particulate SO4= concentration, produced evidence of bronchial irritation in the subjects, but no chronic effect on lung function or lung function growth was detected. PMID:4014164

  14. Race, ideology, and the tea party: a longitudinal study.

    PubMed

    Knowles, Eric D; Lowery, Brian S; Shulman, Elizabeth P; Schaumberg, Rebecca L

    2013-01-01

    The Tea Party movement, which rose to prominence in the United States after the election of President Barack Obama, provides an ideal context in which to examine the roles of racial concerns and ideology in politics. A three-wave longitudinal study tracked changes in White Americans' self-identification with the Tea Party, racial concerns (prejudice and racial identification), and ideologies (libertarianism and social conservatism) over nine months. Latent Growth Modeling (LGM) was used to evaluate potential causal relationships between Tea Party identification and these factors. Across time points, racial prejudice was indirectly associated with movement identification through Whites' assertions of national decline. Although initial levels of White identity did not predict change in Tea Party identification, initial levels of Tea Party identification predicted increases in White identity over the study period. Across the three assessments, support for the Tea Party fell among libertarians, but rose among social conservatives. Results are discussed in terms of legitimation theories of prejudice, the "racializing" power of political judgments, and the ideological dynamics of the Tea Party. PMID:23825630

  15. Longitudinal study of children exposed to sulfur oxides

    SciTech Connect

    Dodge, R.; Solomon, P.; Moyers, J.; Hayes, C.

    1985-05-01

    This study is a longitudinal comparison of the health of children exposed to markedly different concentrations of sulfur dioxide and moderately different concentrations of particulate sulfate. The four groups of subjects lived in two areas of one smelter town and in two other towns, one of which was also a smelter town. In the area of highest pollution, children were intermittently exposed to high SO/sub 2/ levels (peak three-hour average concentration exceeded 2,500 micrograms/m3) and moderate particulate SO/sub 4/= levels (average concentration was 10.1 micrograms/m3). When the children were grouped by the four gradients of pollution observed, the prevalence of cough (measured by questionnaire) correlated significantly with pollution levels (trend chi-square = 5.6, p = 0.02). No significant differences in the incidence of cough or other symptoms occurred among the groups of subjects over three years, and pulmonary function and lung function growth over the study were roughly equal among all the groups. These results suggest that intermittent elevations in SO/sub 2/ concentration, in the presence of moderate particulate SO/sub 4/= concentration, produced evidence of bronchial irritation in the subjects, but no chronic effect on lung function or lung function growth was detected.

  16. Longitudinal study of circulating protein biomarkers in inflammatory bowel disease

    PubMed Central

    Viennois, Emilie; Baker, Mark T.; Xiao, Bo; Wang, Lixin; Laroui, Hamed; Merlin, Didier

    2014-01-01

    Inflammatory bowel diseases (IBD) are chronic and progressive inflammatory disorders of the gastrointestinal tract. In IBD, protein serological biomarkers could be relevant tools for assessing disease activity, performing early-stage diagnosis and managing the treatment. Using the interleukin-10 knockout (IL-10−/−) mouse, a model that develops a time-dependent IBD-like disorder that predominates in the colon; we performed longitudinal studies of circulating protein biomarkers in IBD. Circulating protein profiles in serum samples collected from 30-, 93-, and 135-day-old IL-10−/− mice were investigated using two-dimensional differential gel electrophoresis and MALDI TOF/TOF tandem mass spectrometry. A total of 15 different proteins were identified and confirmed by ELISA and Western blot to be differentially accumulated in serum samples from mid- to late-stage IL-10−/− mice compared to early non-inflamed IL-10−/− mice. The use of another model of colitis and an extra-intestinal inflammation model validated this biomarker panel and demonstrated that comprised some global inflammatory markers, some intestinal inflammation-specific markers and some chronic intestinal inflammation markers. Statistical analyses using misclassification error rate charts validated the use of these identified proteins as powerful biomarkers of colitis. Unlike standard biomarker screening studies, our analyses identified a panel of proteins that allowed the definition of protein signatures that reflect colitis status. PMID:25230104

  17. Race, Ideology, and the Tea Party: A Longitudinal Study

    PubMed Central

    Knowles, Eric D.; Lowery, Brian S.; Shulman, Elizabeth P.; Schaumberg, Rebecca L.

    2013-01-01

    The Tea Party movement, which rose to prominence in the United States after the election of President Barack Obama, provides an ideal context in which to examine the roles of racial concerns and ideology in politics. A three-wave longitudinal study tracked changes in White Americans’ self-identification with the Tea Party, racial concerns (prejudice and racial identification), and ideologies (libertarianism and social conservatism) over nine months. Latent Growth Modeling (LGM) was used to evaluate potential causal relationships between Tea Party identification and these factors. Across time points, racial prejudice was indirectly associated with movement identification through Whites’ assertions of national decline. Although initial levels of White identity did not predict change in Tea Party identification, initial levels of Tea Party identification predicted increases in White identity over the study period. Across the three assessments, support for the Tea Party fell among libertarians, but rose among social conservatives. Results are discussed in terms of legitimation theories of prejudice, the “racializing” power of political judgments, and the ideological dynamics of the Tea Party. PMID:23825630

  18. A longitudinal study of very young children's vowel production

    PubMed Central

    McGowan, Rebecca W.; McGowan, Richard S.; Denny, Margaret; Nittrouer, Susan

    2014-01-01

    Purpose Ecologically realistic, spontaneous adult-directed longitudinal speech data of young children was described by acoustic analyses. Method The first two formant frequencies of vowels produced by six children from different American English dialect regions were analyzed from ages 18 to 48 months. The vowels were from largely conversational contexts and were classified according to dictionary pronunciation. Results Within-subject formant frequency variability remained relatively constant for the span of ages studied here. It was often difficult to detect overall decreases in the first two formant frequencies between the ages of 30 and 48 months. A study of the movement of the corner vowels with respect to the vowel centroid showed that the shape of the vowel space remained qualitatively constant from 30 through 48 months. Conclusions The shape of the vowel space is established early in life. Some aspects of regional dialect were observed in some of the subjects at 42 months of age. The present paper adds to the existing data on the development of vowel spaces by describing ecologically realistic speech. PMID:24687464

  19. Whole grain intake: The Baltimore Longitudinal Study of Aging

    PubMed Central

    Maras, Janice E.; Newby, P.K.; Bakun, Peter J.; Ferrucci, Luigi; Tucker, Katherine L.

    2009-01-01

    Our objective was to identify major dietary sources of whole grains and to describe the construction of a database of whole grain content of foods. Dietary information was collected with 7-d food records from men and women in the Baltimore Longitudinal Study of Aging, mean age 62.1 ± 16.0 years, who participated in the dietary assessment portion of the study (n = 1516), and estimates of whole grain intake were obtained from a newly developed database. The Pyramid Servings database and 1994–1996 Continuing Survey of Food Intakes by Individuals (CSFII) recipe ingredients database were then used to calculate both servings and gram weights of whole grain intakes. Mean intakes of whole grains, refined grains, and total grains, as well as frequency of intake for major whole grain food groups and whole grain content for each group, were calculated. Top contributors of whole grains were ready-to-eat breakfast cereals (made with whole grain as well as bran), hot breakfast cereals (made with whole grain), multi-grain bread, and whole wheat bread. While more research is needed to better understand the benefits of whole grains, the development of research tools, including databases to accurately assess whole grain intake, is a critical step in completing such research. PMID:20126297

  20. Technical report of biota, FEL Site 1, Lawrence Livermore National Laboratory: Final report

    SciTech Connect

    Taylor, D.W.; Davilla, W.; Orloff, S.

    1986-09-26

    Lawrence Livermore National Laboratory is considering an expansion of laser test facilities adjacent to its existing LLNL Site 300 test location. Construction of a free-electron laser, known as the FEL Project, is being considered on approximately 3900 hectates (10,500 acres) of land. We will refer to this proposed site as FEL Site 1. Knowledge of the flora and vegetation resources of the proposed FEL Site 1 is necessary in order to plan for construction, operation, and possible future expansion of the FEL facility. The purpose of botanical sections of this report is to quantitatively describe the variation of vegetation on FEL Site 1, and to relate the vegetation to potential environmental impacts associated with present operation and possible expansion of site facilities. The primary purpose of the wildlife studies was to determine the presence and status of any endangered, threatened, fully protected, or otherwise sensitive species on FEL Site 1 that might be affected by the proposed FEL project. We directed our studies mainly toward the federally endangered San Joaquin kit fox (Vulpes macrotis mutica), but also toward another 14 special status species that potentially occur on site, including the state threatened Alameda striped racer (Masticophis lateralis euryxanthus).

  1. High Power Operation of the JLab IR FEL Driver Accelerator

    SciTech Connect

    Kevin Beard; Stephen Benson; George Biallas; James Boyce; Donald Bullard; James Coleman; David Douglas; H. Dylla; Richard Evans; Pavel Evtushenko; Christopher Gould; Albert Grippo; Joseph Gubeli; David Hardy; Carlos Hernandez-Garcia; J. Hovater; Kevin Jordan; John Klopf; Rui Li; Steven Moore; George Neil; Benard Poelker; Thomas Powers; Joseph Preble; Robert Rimmer; Daniel Sexton; Michelle D. Shinn; Christopher Tennant; Richard Walker; Gwyn Williams; Shukui Zhang

    2007-08-01

    Operation of the JLab IR Upgrade FEL at CW powers in excess of 10 kW requires sustained production of high electron beam powers by the driver ERL. This in turn demands attention to numerous issues and effects, including: cathode lifetime; control of beamline and RF system vacuum during high current operation; longitudinal space charge; longitudinal and transverse matching of irregular/large volume phase space distributions; halo management; management of remnant dispersive effects; resistive wall, wake-field, and RF heating of beam vacuum chambers; the beam break up instability; the impact of coherent synchrotron radiation (both on beam quality and the performance of laser optics); magnetic component stability and reproducibility; and RF stability and reproducibility. We discuss our experience with these issues and describe the modus vivendi that has evolved during prolonged high current, high power beam and laser operation.

  2. A Longitudinal Study on the Stability over Time of School and Teacher Effects on Student Outcomes

    ERIC Educational Resources Information Center

    Kyriakides, Leonidas; Creemers, Bert P. M.

    2008-01-01

    This paper reviews educational effectiveness theory, concentrating on the time stability of the teacher and school effect. The contribution of longitudinal studies investigating the long-term effect of schools and teachers to modelling educational effectiveness is discussed. Findings of a longitudinal study on the progress of students (N=1681) in…

  3. Reducing Bias Due to Systematic Attrition in Longitudinal Studies: The Benefits of Multiple Imputation

    ERIC Educational Resources Information Center

    Asendorpf, Jens B.; van de Schoot, Rens; Denissen, Jaap J. A.; Hutteman, Roos

    2014-01-01

    Most longitudinal studies are plagued by drop-out related to variables at earlier assessments (systematic attrition). Although systematic attrition is often analysed in longitudinal studies, surprisingly few researchers attempt to reduce biases due to systematic attrition, even though this is possible and nowadays technically easy. This is…

  4. The doubly labeled water method produces highly reproducible longitudinal results in nutrition studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The doubly labeled water (DLW) method is considered the reference method for the measurement of energy expenditure under free-living conditions. However, the reproducibility of the DLW method in longitudinal studies is not well documented. This study was designed to evaluate the longitudinal reprodu...

  5. 77 FR 2349 - Proposed Information Collection (Vocational Rehabilitation and Employment Longitudinal Study...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-17

    ... VBA's Vocational Rehabilitation and Employment (VR&E) Program. DATES: Written comments and... . Please refer to ``OMB Control No. 2900--New (VR&E Longitudinal Study Survey)'' in any correspondence...: Vocational Rehabilitation and Employment Longitudinal Study Survey. OMB Control Number: 2900--New...

  6. The Timing of Maternal Depressive Symptoms and Child Cognitive Development: A Longitudinal Study

    ERIC Educational Resources Information Center

    Evans, Jonathan; Melotti, Roberto; Heron, Jon; Ramchandani, Paul; Wiles, Nicola; Murray, Lynne; Stein, Alan

    2012-01-01

    Background: Maternal depression is known to be associated with impairments in child cognitive development, although the effect of timing of exposure to maternal depression is unclear. Methods: Data collected for the Avon Longitudinal Study of Parents and Children, a longitudinal study beginning in pregnancy, included self-report measures of…

  7. Peer Victimization in Childhood and Internalizing Problems in Adolescence: A Prospective Longitudinal Study

    ERIC Educational Resources Information Center

    Zwierzynska, Karolina; Wolke, Dieter; Lereya, Tanya S.

    2013-01-01

    Traumatic childhood experiences have been found to predict later internalizing problems. This prospective longitudinal study investigated whether repeated and intentional harm doing by peers (peer victimization) in childhood predicts internalizing symptoms in early adolescence. 3,692 children from the Avon Longitudinal Study of Parents and…

  8. Variable selection for semiparametric mixed models in longitudinal studies.

    PubMed

    Ni, Xiao; Zhang, Daowen; Zhang, Hao Helen

    2010-03-01

    We propose a double-penalized likelihood approach for simultaneous model selection and estimation in semiparametric mixed models for longitudinal data. Two types of penalties are jointly imposed on the ordinary log-likelihood: the roughness penalty on the nonparametric baseline function and a nonconcave shrinkage penalty on linear coefficients to achieve model sparsity. Compared to existing estimation equation based approaches, our procedure provides valid inference for data with missing at random, and will be more efficient if the specified model is correct. Another advantage of the new procedure is its easy computation for both regression components and variance parameters. We show that the double-penalized problem can be conveniently reformulated into a linear mixed model framework, so that existing software can be directly used to implement our method. For the purpose of model inference, we derive both frequentist and Bayesian variance estimation for estimated parametric and nonparametric components. Simulation is used to evaluate and compare the performance of our method to the existing ones. We then apply the new method to a real data set from a lactation study. PMID:19397585

  9. Parent-Offspring Similarity for Drinking: A Longitudinal Adoption Study

    PubMed Central

    McGue, Matt; Malone, Steve; Keyes, Margaret; Iacono, William G.

    2015-01-01

    Parent-offspring resemblance for drinking was investigated in a sample of 409 adopted and 208 non-adopted families participating in the Sibling Interaction and Behavior Study (SIBS). Drinking data was available for 1229 offspring, assessed longitudinally up to three times in the age range from 10 to 28 years. A single drinking index was computed from four items measuring quantity, frequency and density of drinking. As expected, the mean drinking index increased with age, was greater in males as compared to females (although not at the younger ages), but did not vary significantly by adoption status. Parent-offspring correlation in drinking did not vary significantly by either offspring or parent gender but did differ significantly by adoption status. In adopted families, the parent-offspring correlation was statistically significant at all ages but decreased for the oldest age group (age 22–28). In non-adopted families, the parent-offspring correlation was statistically significant at all ages and increased in the oldest age group. Findings imply that genetic influences on drinking behavior increase with age while shared family environment influences decline, especially during the transition from late-adolescence to early adulthood. PMID:25224596

  10. Minor delinquency and immigration: a longitudinal study among male adolescents.

    PubMed

    Titzmann, Peter F; Silbereisen, Rainer K; Mesch, Gustavo

    2014-01-01

    On the basis of general theories of delinquency and the specific situation of immigrants, this longitudinal study investigated predictors of initial levels and rates of change in delinquency among 188 male ethnic German Diaspora immigrants from the former Soviet Union (FSU) in Germany, 237 male native German adolescents, and 182 male Jewish Diaspora adolescents from the FSU in Israel. The participants (15.2 years old) completed 3 annual assessments. Latent growth curve models showed that ethnic German adolescents reported higher initial levels of delinquency than native German adolescents and lower levels than the Russian Jewish adolescents. Groups did not differ in the rate of change, indicating a decrease in delinquency over time. Peer-oriented leisure related positively and parental knowledge negatively with levels and change rates in delinquency in all groups, but could not fully account for the ethnic differences in delinquency levels. School bonding was associated negatively with delinquency only among native German adolescents. Acculturation-related hassles were an additional predictor for higher levels and also associated with change rates in the immigrant groups. Thus, general theories of delinquency apply to immigrants, but may be complemented by adding acculturation-specific challenges. PMID:23586943