WorldWideScience

Sample records for vairac cretin longitudinal

  1. More on the Liang Bua finds and modern human cretins.

    Science.gov (United States)

    Oxnard, Charles; Obendorf, Peter J; Kefford, Ben J; Dennison, John

    2012-12-01

    Brown (2012: LB1 and LB6 Homo floresiensis are not modern human (Homo sapiens) cretins, Journal of Human Evolution) makes errors of fact, omission and interpretation. Brown's comments refer, among others, to (1) delayed growth and development indicated by unfused epiphyses, (2) postcranial limb proportions: limbs to trunk, between limbs, and within limbs, (3) postcranial bone torsions and angles, (4) postcranial robusticity, real and apparent, (5) skull features, and (6) cretinism on Flores. In each of these areas, much information about cretins is incorrect and much information (Oxnard et al., 2010) comparing the Liang Bua remains with cretins is ignored. Copyright © 2012 Elsevier GmbH. All rights reserved.

  2. LB1 and LB6 Homo floresiensis are not modern human (Homo sapiens) cretins.

    Science.gov (United States)

    Brown, Peter

    2012-02-01

    Excavations in the late Pleistocene deposits at Liang Bua cave, Flores, have uncovered the skeletal remains of several small-bodied and small-brained hominins in association with stone artefacts and the bones of Stegodon. Due to their combination of plesiomorphic, unique and derived traits, they were ascribed to a new species, Homo floresiensis, which, along with Stegodon, appears to have become extinct ∼17 ka (thousand years ago). However, recently it has been argued that several characteristics of H. floresiensis were consistent with dwarfism and evidence of delayed development in modern human (Homo sapiens) myxoedematous endemic (ME) cretins. This research compares the skeletal and dental morphology in H. floresiensis with the clinical and osteological indicators of cretinism, and the traits that have been argued to be associated with ME cretinism in LB1 and LB6. Contrary to published claims, morphological and statistical comparisons did not identify the distinctive skeletal and dental indicators of cretinism in LB1 or LB6 H. floresiensis. Brain mass, skeletal proportions, epiphyseal union, orofacial morphology, dental development, size of the pituitary fossa and development of the paranasal sinuses, vault bone thickness and dimensions of the hands and feet all distinguish H. floresiensis from modern humans with ME cretinism. The research team responsible for the diagnosis of ME cretinism had not examined the original H. floresiensis skeletal materials, and perhaps, as a result, their research confused taphonomic damage with evidence of disease, and thus contained critical errors of fact and interpretation. Behavioural scenarios attempting to explain the presence of cretinous H. sapiens in the Liang Bua Pleistocene deposits, but not unaffected H. sapiens, are both unnecessary and not supported by the available archaeological and geochronological evidence from Flores. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  3. Post-cranial skeletons of hypothyroid cretins show a similar anatomical mosaic as Homo floresiensis.

    Science.gov (United States)

    Oxnard, Charles; Obendorf, Peter J; Kefford, Ben J

    2010-09-27

    Human remains, some as recent as 15 thousand years, from Liang Bua (LB) on the Indonesian island of Flores have been attributed to a new species, Homo floresiensis. The definition includes a mosaic of features, some like modern humans (hence derived: genus Homo), some like modern apes and australopithecines (hence primitive: not species sapiens), and some unique (hence new species: floresiensis). Conversely, because only modern humans (H. sapiens) are known in this region in the last 40 thousand years, these individuals have also been suggested to be genetic human dwarfs. Such dwarfs resemble small humans and do not show the mosaic combination of the most complete individuals, LB1 and LB6, so this idea has been largely dismissed. We have previously shown that some features of the cranium of hypothyroid cretins are like those of LB1. Here we examine cretin postcrania to see if they show anatomical mosaics like H. floresiensis. We find that hypothyroid cretins share at least 10 postcranial features with Homo floresiensis and unaffected humans not found in apes (or australopithecines when materials permit). They share with H. floresiensis, modern apes and australopithecines at least 11 postcranial features not found in unaffected humans. They share with H. floresiensis, at least 8 features not found in apes, australopithecines or unaffected humans. Sixteen features can be rendered metrically and multivariate analyses demonstrate that H. floresiensis co-locates with cretins, both being markedly separate from humans and chimpanzees (P0.999). We therefore conclude that LB1 and LB6, at least, are, most likely, endemic cretins from a population of unaffected Homo sapiens. This is consistent with recent hypothyroid endemic cretinism throughout Indonesia, including the nearby island of Bali.

  4. Post-cranial skeletons of hypothyroid cretins show a similar anatomical mosaic as Homo floresiensis.

    Directory of Open Access Journals (Sweden)

    Charles Oxnard

    Full Text Available Human remains, some as recent as 15 thousand years, from Liang Bua (LB on the Indonesian island of Flores have been attributed to a new species, Homo floresiensis. The definition includes a mosaic of features, some like modern humans (hence derived: genus Homo, some like modern apes and australopithecines (hence primitive: not species sapiens, and some unique (hence new species: floresiensis. Conversely, because only modern humans (H. sapiens are known in this region in the last 40 thousand years, these individuals have also been suggested to be genetic human dwarfs. Such dwarfs resemble small humans and do not show the mosaic combination of the most complete individuals, LB1 and LB6, so this idea has been largely dismissed. We have previously shown that some features of the cranium of hypothyroid cretins are like those of LB1. Here we examine cretin postcrania to see if they show anatomical mosaics like H. floresiensis. We find that hypothyroid cretins share at least 10 postcranial features with Homo floresiensis and unaffected humans not found in apes (or australopithecines when materials permit. They share with H. floresiensis, modern apes and australopithecines at least 11 postcranial features not found in unaffected humans. They share with H. floresiensis, at least 8 features not found in apes, australopithecines or unaffected humans. Sixteen features can be rendered metrically and multivariate analyses demonstrate that H. floresiensis co-locates with cretins, both being markedly separate from humans and chimpanzees (P0.999. We therefore conclude that LB1 and LB6, at least, are, most likely, endemic cretins from a population of unaffected Homo sapiens. This is consistent with recent hypothyroid endemic cretinism throughout Indonesia, including the nearby island of Bali.

  5. Analysis of pituitary-thyroid functional condition in neurotic type of endemic cretinism in Beijing

    International Nuclear Information System (INIS)

    Zhao Peiqin; Yuan Shenyuan; Wang Ruihua; Xiao Feng

    1992-01-01

    The authors reported 57 patients with endemic cretinism from 1981 to 1984, 41 of which were proved to be nervous endemic cretinism. The severe mental disorders were the main manifestations. But thyroid gland function was mostly normal. Tg-Ab was negative. The location size, shape of thyroid and distribution of radioactive 131 I in thyroid gland were normal. The main cause of this disease is deficiency of thyroxine and iodine during embryo period, resulting in irreversible damages in proliferation, differentiation and maturation of nervous system

  6. The influence of iodine and selenium supplementation on trace elemental contents in erythrocyte of the cretinism rats

    International Nuclear Information System (INIS)

    Liu Nianqing; Liu Pingsheng

    2001-01-01

    The contents of K, Ca, Mn, Fe, Cr, Cu, Zn, Rb and Pb in the erythrocyte of 5 groups of rats, were measured by PIXE and XRF. Four groups of the cretinism rats were continuously fed the feed from epidemic cretinism area. zone sandstone-type uranium deposit mineral haloes of intesupplementation. Control group was normal rats fed normal feed. Five weeks later the blood samples were collected. The erythrocyte was separated for the determination of elemental concentrations, the serum for the radioimmunoassay of thyroid hormones T3, T4, FT3, FT4 and rT3 status. The comparison among five groups and the correlation between elements and thyroid hormones were performed by using SPSS/PC statistical package. The results showed that comparing with non-supplementation or control groups the concentrations of Zn, Mn, Cu, or Rb in the groups of I and/or Se supplementation were significantly fluctuating, while thyroid hormones T4, FT4 and rT3 significantly increased

  7. Internato Longitudinal

    Directory of Open Access Journals (Sweden)

    Marcelo Marcos Piva Demarzo

    Full Text Available O internato médico tem gerado recorrente debate frente às transformações curriculares em andamento no País. A despeito das discussões, um modelo de internato consonante com essas mudanças ainda não foi consistentemente delineado. Neste ensaio, trazemos uma proposta de matriz estruturante para o internato médico. Propomos que o internato médico seja realizado durante os seis anos do curso, de forma longitudinal, tendo como eixo estruturante a clínica da Atenção Básica (AB. Esse modelo de "internato longitudinal" prevê a introdução progressiva na prática clínica, iniciando-se pela AB nos dois primeiros anos, acrescentando-se progressivamente os ambulatórios de especialidades, os estágios hospitalares e demais atividades práticas, alcançando-se, dessa forma, o rol de diversidade e complexidade previsto para o egresso da escola médica.

  8. Applied longitudinal analysis

    CERN Document Server

    Fitzmaurice, Garrett M; Ware, James H

    2012-01-01

    Praise for the First Edition "". . . [this book] should be on the shelf of everyone interested in . . . longitudinal data analysis.""-Journal of the American Statistical Association   Features newly developed topics and applications of the analysis of longitudinal data Applied Longitudinal Analysis, Second Edition presents modern methods for analyzing data from longitudinal studies and now features the latest state-of-the-art techniques. The book emphasizes practical, rather than theoretical, aspects of methods for the analysis of diverse types of lo

  9. Restoration of longitudinal images.

    Science.gov (United States)

    Hu, Y; Frieden, B R

    1988-01-15

    In this paper, a method of restoring longitudinal images is developed. By using the transfer function for longitudinal objects, and inverse filtering, a longitudinal image may be restored. The Fourier theory and sampling theorems for transverse images cannot be used directly in the longitudinal case. A modification and reasonable approximation are introduced. We have numerically established a necessary relationship between just-resolved longitudinal separation (after inverse filtering), noise level, and the taking conditions of object distance and lens diameter. An empirical formula is also found to well-fit the computed results. This formula may be of use for designing optical systems which are to image longitudinal details, such as in robotics or microscopy.

  10. On Longitudinal Spectral Coherence

    DEFF Research Database (Denmark)

    Kristensen, Leif

    1979-01-01

    It is demonstrated that the longitudinal spectral coherence differs significantly from the transversal spectral coherence in its dependence on displacement and frequency. An expression for the longitudinal coherence is derived and it is shown how the scale of turbulence, the displacement between ...... observation sites and the turbulence intensity influence the results. The limitations of the theory are discussed....

  11. Longitudinal categorical data analysis

    CERN Document Server

    Sutradhar, Brajendra C

    2014-01-01

    This is the first book in longitudinal categorical data analysis with parametric correlation models developed based on dynamic relationships among repeated categorical responses. This book is a natural generalization of the longitudinal binary data analysis to the multinomial data setup with more than two categories. Thus, unlike the existing books on cross-sectional categorical data analysis using log linear models, this book uses multinomial probability models both in cross-sectional and longitudinal setups. A theoretical foundation is provided for the analysis of univariate multinomial responses, by developing models systematically for the cases with no covariates as well as categorical covariates, both in cross-sectional and longitudinal setups. In the longitudinal setup, both stationary and non-stationary covariates are considered. These models have also been extended to the bivariate multinomial setup along with suitable covariates. For the inferences, the book uses the generalized quasi-likelihood as w...

  12. Longitudinal beam dynamics

    International Nuclear Information System (INIS)

    Tecker, F

    2014-01-01

    The course gives a summary of longitudinal beam dynamics for both linear and circular accelerators. After discussing different types of acceleration methods and synchronism conditions, it focuses on the particle motion in synchrotrons

  13. LIA longitudinal coupling impedance

    International Nuclear Information System (INIS)

    Faltens, A.

    1980-01-01

    The beam generated fields enter into the problems of waveform generation and longitudinal stability. In the former, provision must be made for the longitudinally defocusing forces due to the space charge and the beam loading effects on the accelerating voltage due to the current of a presumably known bunch. In the latter, the concern is for the growth of unintentional perturbations to unacceptably large values through the interaction of the charge and current fluctuations with the rest of the beam and the surrounding structures. These beam generated electric fields may be related to the beam current through a coupling impedance

  14. Longitudinal joint specifications and performance.

    Science.gov (United States)

    2012-08-01

    Deterioration of longitudinal joints is widely recognized as one of the major factors contributing to failure of asphalt pavements. Finding : ways to improve the durability of longitudinal joints will lead to improved service lives and lower life cyc...

  15. A Pluralistic, Longitudinal Method

    DEFF Research Database (Denmark)

    Evers, Winie; Marroun, Sana; Young, Louise

    2017-01-01

    There is recognition in business markets of the need for connected relationships to enable the survival and growth of firms. Finding new ways to collaborate enables firms to better seek opportunities and challenges and enhance network capability. However the traditional methods used to research...... and analysis. Longitudinal research considers a Danish advertising and communication firm looking for new ideas by involving their network in order to help them to compete in their environment of rapid globalization and emergence of new technologies. A five stage research design considered how network...

  16. A longitudinal study

    OpenAIRE

    Kristen, Astrid

    2010-01-01

    Does playing violent video games increase aggressive behavior over time or is it aggressive children who increasingly seek out (and play) these violent video games? To study such long-term effects a longitudinal design is necessary. Within a field study in a large German city (Kinder, Computer, Hobby, Lernen – KUHL, Freie Universtität Berlin) about 115 elementary school boys attending in the beginning (t1) classrooms of the third and fourth grade and twelve months later (t2) classrooms of the...

  17. Bunched beam longitudinal stability

    International Nuclear Information System (INIS)

    Baartman, R.

    1991-05-01

    Instabilities driven by narrow-band impedances can be stabilized by Landau damping arising from the synchrotron frequency spread due to the nonlinearity of the rf wave-form. We calculate stability diagrams for various phase space distributions. We find that distributions without tails are unstable in the 'negative mass' regime (inductive impedance below transition or capacitive impedance above transition). We also find that longitudinal instability thresholds of the (usually neglected) higher order radial modes are lower than expected. For example, the next to lowest dipole mode has a lower threshold than the lowest sextupole mode even though the latter has the larger growth rate in the absence of Landau damping. (Author) 5 refs., 5 figs

  18. LEIR longitudinal studies

    CERN Document Server

    Albright, S; Hancock, S

    2017-01-01

    Towards the end of 2015 and during 2016 there were exten-sive studies of longitudinal beam dynamics in LEIR aimedat improving extracted intensities. As the driving source oflosses early in the ramp was shown to be transverse spacecharge tune spread a significant improvement came fromflattening the beam profile to increase the bunching factorby offsetting the RF frequency from the beam revolution fre-quency. Further benefits were provided by modulating theRF frequency during capture, leading to emittance blow-upand improved reproducibility. The use of two RF cavitiesduring operation was studied to try and further increase thecaptured emittance, however after careful alignment of theRF it was found that a hard limit in the bunch heigh of approx-imately 7 MeV exists. Due to the acceptance limit there wasno operational benefit to using both cavities simultaneously

  19. Fundamentals - longitudinal motion

    International Nuclear Information System (INIS)

    Weng, W.T.

    1989-01-01

    There are many ways to accelerate charged particles to high energy for physics research. Each has served its purpose but eventually has encountered fundamental limitations of one kind or another. Looking at the famous Livingston curve, the initial birth and final level-off of all types of accelerators is seen. In fact, in the mid-80s we personally witnessed the creation of a new type of collider - the Stanford Linear Collider. Also witnessed, was the resurgence of study into novel methods of acceleration. This paper will cover acceleration and longitudinal motion in a synchrotron. A synchrotron is a circular accelerator with the following three characteristics: (1) Magnetic guiding (dipole) and confinement (quadrupole) components are placed in a small neighborhood around the equilibrium orbit. (2) Particles are kept in resonance with the radio-frequency electric field indefinitely to achieve acceleration to higher energies. (3) Magnetic fields are varied adiabatically with the energy of the particle. D. Edwards described the transverse oscillations of particles in a synchrotron. Here the author talks about the longitudinal oscillations of particles. The phase stability principle was invented by V. Veksler and E. McMillan independently in 1945. The phase stability and strong focusing principle, invented by Courant and Livingston in 1952, enabled the steady energy gain of accelerators and storage rings witnessed during the past 30 years. This paper is a unified overview of the related rf subjects in an accelerator and a close coupling between accelerator physics and engineering practices, which is essential for the major progress in areas such as high intensity synchrotrons, a multistage accelerator complex, and anti-proton production and cooling, made possible in the past 20 years

  20. Loading Conditions and Longitudinal Strength

    DEFF Research Database (Denmark)

    Sørensen, Herman

    1995-01-01

    Methods for the calculation of the lightweight of the ship.Loading conditions satisfying draught, trim and intact stability requirements and analysis of the corresponding stillwater longitudinal strength.......Methods for the calculation of the lightweight of the ship.Loading conditions satisfying draught, trim and intact stability requirements and analysis of the corresponding stillwater longitudinal strength....

  1. Longitudinal Research with Latent Variables

    CERN Document Server

    van Montfort, Kees; Satorra, Albert

    2010-01-01

    This book combines longitudinal research and latent variable research, i.e. it explains how longitudinal studies with objectives formulated in terms of latent variables should be carried out, with an emphasis on detailing how the methods are applied. Because longitudinal research with latent variables currently utilizes different approaches with different histories, different types of research questions, and different computer programs to perform the analysis, the book is divided into nine chapters. Starting from some background information about the specific approach, short history and the ma

  2. Summary of longitudinal instabilities workshop

    Energy Technology Data Exchange (ETDEWEB)

    Chasman, R.

    1976-01-01

    A five-day ISABELLE workshop on longitudinal instabilities was held at Brookhaven, August 9-13, 1976. About a dozen outside accelerator experts, both from Europe and the U.S.A., joined the local staff for discussions of longitudinal instabilities in ISABELLE. An agenda of talks was scheduled for the first day of the workshop. Later during the week, a presentation was given on the subject ''A more rigorous treatment of Landau damping in longitudinal beam instabilities''. A few progress meetings were held in which disagreements regarding calculations of coupling impedances were clarified. A summary session was held on the last day. Heavy emphasis was put on single bunched beam instabilities in the microwave region extending above the cut-off frequency of the ISABELLE vacuum chamber.

  3. Longitudinal dynamics in storage rings

    International Nuclear Information System (INIS)

    Colton, E.P.

    1986-01-01

    The single-particle equations of motion are derived for charged particles in a storage ring. Longitudinal space charge is included in the potential assuming an infinitely conducting circular beam pipe with a distributed inductance. The framework uses Hamilton's equations with the canonical variables phi and W. The Twiss parameters for longitudinal motion are also defined for the small amplitude synchrotron oscillations. The space-charge Hamiltonian is calculated for both parabolic bunches and ''matched'' bunches. A brief analysis including second-harmonic rf contributions is also given. The final sections supply calculations of dynamical quantities and particle simulations with the space-charge effects neglected

  4. Longitudinal single-bunch instabilities

    International Nuclear Information System (INIS)

    Migliorati, M.; Palumbo, L.; Rome Univ. La Sapienza, Rome

    2001-02-01

    After introducing the concepts of longitudinal wakefield and coupling impedance, it is reviewed the theory of longitudinal single-bunch collective effects in storage rings. From the Fokker-Planck equation it is first derived the stationary solution describing the natural single-bunch regime, and then treat the problem of microwave instability, showing the different approaches used for estimating the threshold current. The lecture is ended with the semi-empirical laws that allow everyone to obtain the single-bunch behaviour above threshold, and with a description of the simulation codes that are now reliable tools for investigating all these effects

  5. Passive longitudinal phase space linearizer

    Directory of Open Access Journals (Sweden)

    P. Craievich

    2010-03-01

    Full Text Available We report on the possibility to passively linearize the bunch compression process in electron linacs for the next generation x-ray free electron lasers. This can be done by using the monopole wakefields in a dielectric-lined waveguide. The optimum longitudinal voltage loss over the length of the bunch is calculated in order to compensate both the second-order rf time curvature and the second-order momentum compaction terms. Thus, the longitudinal phase space after the compression process is linearized up to a fourth-order term introduced by the convolution between the bunch and the monopole wake function.

  6. Longitudinal feedback system for PEP

    International Nuclear Information System (INIS)

    Allen, M.A.; Cornacchia, M.; Millich, A.

    1979-02-01

    Whether the wide bandwidth longitudinal feedback system described in this paper is made to act on the individual modes in frequency domain or on the individual bunches in time domain, it represents a clean and efficient way of damping the longitudinal oscillations without influencing other beam parameters such as bunch shape or synchrotron frequency distribution. The frequency domain feedback presents the advantage of providing information on which modes are unstable and on their risetimes, which may be helpful in locating dangerous resonators in the ring

  7. Longitudinal bulk acoustic mass sensor

    DEFF Research Database (Denmark)

    Hales, Jan Harry; Teva, Jordi; Boisen, Anja

    2009-01-01

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10(-15) g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise...

  8. Correspondence analysis of longitudinal data

    NARCIS (Netherlands)

    Van der Heijden, P.G.M.|info:eu-repo/dai/nl/073087998

    2005-01-01

    Correspondence analysis is an exploratory tool for the analysis of associations between categorical variables, the results of which may be displayed graphically. For longitudinal data with two time points, an analysis of the transition matrix (showing the relative frequencies for pairs of

  9. Longitudinal heritability of childhood aggression

    NARCIS (Netherlands)

    Porsch, R.M.P.; Middeldorp, C.M.; Cherny, S.S.; Krapohl, E.; van Beijsterveldt, C.E.M.; Loukola, A.; Korhonen, T.; Pulkkinen, L.; Corley, R.P.; Rhee, S.; Kaprio, J.; Rose, R.; Hewitt, J.K.; Sham, P.; Plomin, R.; Boomsma, D.I.; Bartels, M.

    2016-01-01

    The genetic and environmental contributions to the variation and longitudinal stability in childhood aggressive behavior were assessed in two large twin cohorts, the Netherlands Twin Register (NTR), and the Twins Early Development Study (TEDS; United Kingdom). In NTR, maternal ratings on aggression

  10. Single bunch fast longitudinal instability

    International Nuclear Information System (INIS)

    Wang, J.M.; Pellegrini, C.

    1979-01-01

    Single bunch longitudinal instability producing an increase of the bunch area have been observed in proton synchrotron and storage rings. Signals at microwave frequencies are observed during the bunch blow-up and because of this the effect has been called the microwave instability. A similar increase in bunch area is observed also in electron storage rings, where it is usually referred to as the bunch lengthening effect. This paper is an attempt to obtain a more general theory of this effect. Here we describe the model used and the method of calculation, together with some general results. More detailed results will be given in another paper. The main result is the derivation of a condition for the existence of a fast longitudinal bunch blow-up. This condition is a generalized threshold formula, showing explicitly the dependence on the bunch energy spread and length. This condition is qualitatively in agreement with Boussard's suggestion

  11. Single bunch fast longitudinal instability

    International Nuclear Information System (INIS)

    Wang, J.M.; Pellegrini, C.

    1979-01-01

    Single bunch longitudinal instability producing an increase of the bunch areas has been observed in proton synchrotron and storage rings. Singals at microwave frequencies are observed during the bunch blow-up and because of this the effect has been called the microwave instability. A similar increase in bunch area is observed also in electron storage rings, where it is usually referred to as the bunch lengthening effect. This paper is an attempt to obtain a more general theory of this effect. Here we describe the model used and the method of calculation, together with some general results. The main result of this paper is the derivation of a condition for the existence of a fast longitudinal bunch blow-up. This condition is a generalized threshold formula, showing explicitly the dependence on the bunch energy spread and length

  12. Parameterized Linear Longitudinal Airship Model

    Science.gov (United States)

    Kulczycki, Eric; Elfes, Alberto; Bayard, David; Quadrelli, Marco; Johnson, Joseph

    2010-01-01

    A parameterized linear mathematical model of the longitudinal dynamics of an airship is undergoing development. This model is intended to be used in designing control systems for future airships that would operate in the atmospheres of Earth and remote planets. Heretofore, the development of linearized models of the longitudinal dynamics of airships has been costly in that it has been necessary to perform extensive flight testing and to use system-identification techniques to construct models that fit the flight-test data. The present model is a generic one that can be relatively easily specialized to approximate the dynamics of specific airships at specific operating points, without need for further system identification, and with significantly less flight testing. The approach taken in the present development is to merge the linearized dynamical equations of an airship with techniques for estimation of aircraft stability derivatives, and to thereby make it possible to construct a linearized dynamical model of the longitudinal dynamics of a specific airship from geometric and aerodynamic data pertaining to that airship. (It is also planned to develop a model of the lateral dynamics by use of the same methods.) All of the aerodynamic data needed to construct the model of a specific airship can be obtained from wind-tunnel testing and computational fluid dynamics

  13. Bayesian Nonparametric Longitudinal Data Analysis.

    Science.gov (United States)

    Quintana, Fernando A; Johnson, Wesley O; Waetjen, Elaine; Gold, Ellen

    2016-01-01

    Practical Bayesian nonparametric methods have been developed across a wide variety of contexts. Here, we develop a novel statistical model that generalizes standard mixed models for longitudinal data that include flexible mean functions as well as combined compound symmetry (CS) and autoregressive (AR) covariance structures. AR structure is often specified through the use of a Gaussian process (GP) with covariance functions that allow longitudinal data to be more correlated if they are observed closer in time than if they are observed farther apart. We allow for AR structure by considering a broader class of models that incorporates a Dirichlet Process Mixture (DPM) over the covariance parameters of the GP. We are able to take advantage of modern Bayesian statistical methods in making full predictive inferences and about characteristics of longitudinal profiles and their differences across covariate combinations. We also take advantage of the generality of our model, which provides for estimation of a variety of covariance structures. We observe that models that fail to incorporate CS or AR structure can result in very poor estimation of a covariance or correlation matrix. In our illustration using hormone data observed on women through the menopausal transition, biology dictates the use of a generalized family of sigmoid functions as a model for time trends across subpopulation categories.

  14. Myxedematous cretinism with dwarfism or Spanish painting in doctor's collection and unforgettable French park

    Directory of Open Access Journals (Sweden)

    G A Melnichenko

    2010-12-01

    Full Text Available Долина королей, долина Луары – зачарованное место памятников истории и волшебных замков, удивительных садов и поразительных историй. В од- ном таком замке – Вилландри (http://www.chateauvillandry.fr/en неподалеку от Тура, переплелись французская история и история медицины. Своей нынешней славой замок обязан испанскому врачу Joachim Carvallo, родившемуся в Испании в 1869 г., прапрадедушке нынешнего владельца. Его медицинская карьера проходила в клинике профессора Charles Richet, нобелевского лауреата 1913 г. (работы по асфиксии, но после женитьбы он приобрел замок Вилландри, разместил там свою коллекцию испанской живописи и реализовал мечту о создании идеальных садов, жизни в гармонии с природой, среди посаженных человеком растений и деревьев в замке эпохи Ренессанса. Вероятно, контраст безмятежной красоты природы, и безупречной архитектуры, и трагического реализма испанских полотен был особенно важен доктору Корвалло, и среди его картин оказалась маленькая работа неизвестного автора, предположительно школы Гойи (рис.. Эта картина ранее не фигурировала, насколько мне известно, среди работ, описывающих те или иные изображения гипотиреоза и микседематозной карликовости, но нынешний владелец замка и директор музея Вилландри Henri Corvallo (Анри Корвалло любезно разрешил мне использовать репродукцию картины (и прислал ее для публикации и выразил удовлетворение тем, что теперь он сможет более точно атрибутировать конкретный тип карликовости изображенного на полотне лица. Надо сказать, что гипотиреоз, развившийся в зрелом возрасте, имеет много характерных черт, но для подтверждения диагноза, как бы ни была типична клиника, мы все равно сегодня будем исследовать ТТГ и св. Т4 и только после этого представим историю болезни на публикацию. Другое дело – изображения лиц с врожденным гипотиреозом, со всеми признаки фатальной задержки развития и роста, которые несет отсутствие жизненно необходимых тиреоидных гормонов. Изображенный человек не юн, и мы с уверенностью можем сказать, что он рожден не в нищей семье и за ним сохраняется уход. Пропорции его тела – иллюстрация из старых учебников о типичном внешнем виде не получавших лечение больных с врожденным гипотиреозом: непропорционально большая голова, западающая переносица, маленькие кисти и стопы, карликовость, скудный рост волос на голове, одутловатое лицо. Живописец добросовестно фиксирует особый желтоватый цвет кожи нашего арт-пациента. Рассматривая эту картину, эндокринолог не может не думать о том, как изменилась судьба людей с врожденным гипотиреозом после создания методов определения ТТГ, введения неонатального скрининга и реализации программ ликвидации тяжелого йодного дефицита. Хочется верить, что картина с карликом из Вилландри, наряду с другими подобными картинами, навсегда станет только достоянием искусства и никогда мы не будем иметь возможность получать фотографии подобных больных в XXI веке. Но один вопрос так и остается для меня неясным: почему все-таки возможно сравнительно длительное выживание лиц с врожденным гипотиреозом и что является причиной их смерти без лечения?

  15. Short stature with umbilical hernia - Not always due to cretinism: A report of two cases

    Directory of Open Access Journals (Sweden)

    Sharvil S Gadve

    2012-01-01

    Full Text Available A 7-year-old boy presented with umbilical hernia and short stature. Growth retardation, recurrent upper respiratory tract infections and delayed developmental milestones were present from infancy. Umbilical hernia was diagnosed at the age of 5 years. On examination, he had short-trunk dwarfism, large head circumference, coarse facial features, joint stiffness, hepatosplenomegaly, and mild mental retardation. He had normal biochemical parameters, thyroid function tests and arterial blood gas analysis. Radiological evaluation showed that the child had Hunter syndrome with findings of J-shaped sellaturcica, proximal bulleting of metacarpals, spatulated ribs and anterior beaking of lumbar vertebrae. The second case was a 6-year-old girl with umbilical hernia, short stature, normal biochemistry and radiological findings of mucopolysaccharidosis. However, she also had corneal opacity; confirmed by slit-lamp examination, which led to the diagnosis of Hurler-Scheie syndrome. Enzymatic studies could not be done in both the cases, as they are not available at most centers.

  16. Thiocyanate in food and iodine in milk: From domestic animal feeding to improved understanding of cretinism

    DEFF Research Database (Denmark)

    Laurberg, P.; Andersen, S.; Knudsen, N.

    2002-01-01

    of their breastfed children. Second, iodine in dairy products provides a considerable part of iodine intake in many populations. Thiocyanate from rapeseed feeding of cows decreases milk iodine content, probably by competitive inhibition of NIS in the mammary gland. Alterations in feeding of dairy cows may alter...

  17. A study of the HEB longitudinal dynamics

    International Nuclear Information System (INIS)

    Larson, D.J.

    1993-12-01

    A study of the High Energy Booster (HEB) longitudinal dynamics is presented. Full derivations of ramp dependent longitudinal variables are given. The formulas assume that the input magnetic field and beam longitudinal emittance are known as a function of time, and that either the rf voltage or the rf bucket area are known as a function of time. Once these three inputs are specified, the formulas can be used to calculate values for all other longitudinal dynamics variables. The formulas have been incorporated into a single computer code named ELVIRA: Evaluation of Longitudinal Variables in Relativistic Accelerators. The ELVIRA code is documented here in detail. The ELVIRA code is used under two initial longitudinal emittance assumptions to plot ramp functions for the longitudinal dynamics design of the HEB as of May 5, 1992

  18. Longitudinal tune control in synchrotrons

    International Nuclear Information System (INIS)

    Colton, E.P.

    1984-01-01

    Dual rf systems that use fundamental and higher-harmonic cavities can be used to control the longitudinal tune in synchrotrons. The equations of motion and the Hamiltonian are defined for particle motion using dual rf systems. An example is considered using a second-harmonic system - it is shown, that as phi/sub s/ is increased, a substantial gain in bucket area over a single rf system can be realized by proper relative phasing of the first- and second-harmonic voltages

  19. Exploring Longitudinal Risk-return Relationships

    DEFF Research Database (Denmark)

    Andersen, Torben J.; Bettis, Richard A.

    2015-01-01

    We study a longitudinal fit model of adaptation and its association with the longitudinal risk-return relationship. The model allows the firm to adjust its position in response to partial learning about a changing environment characterized by two path-dependent processes—a random walk and a stoch......We study a longitudinal fit model of adaptation and its association with the longitudinal risk-return relationship. The model allows the firm to adjust its position in response to partial learning about a changing environment characterized by two path-dependent processes—a random walk...... can lead to the inverse longitudinal risk-return relationships observed empirically. We discuss this apparent paradox and the possible resolution between mindless and conscious behavior as plausible causes of the longitudinal Bowman Paradox....

  20. Longitudinal study of fingerprint recognition.

    Science.gov (United States)

    Yoon, Soweon; Jain, Anil K

    2015-07-14

    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.

  1. Longitudinal Space Charge in the SPS

    CERN Document Server

    Lasheen, Alexandre

    2016-01-01

    Longitudinal instabilities due to the SPS beam coupling impedance are a major issue for future projects and it is essential to have an accurate SPS impedance model to study them. The longitudinal space charge effect can be modelled by a pure reactive impedance and should also be included in simulations as it may have an impact at low energy. In this Note, the effect of the longitudinal space charge in the SPS is evaluated by taking into account the variation of the transverse beam size and vacuum chamber geometry along the ring. Scaling laws are used to investigate what are the most important parameters for the evaluation of the longitudinal space charge impedance.

  2. Introduction to Longitudinal Beam Dynamics

    International Nuclear Information System (INIS)

    Holzer, B J

    2014-01-01

    This chapter gives an overview of the longitudinal dynamics of the particles in an accelerator and, closely related to that, the issue of synchronization between the particles and the accelerating field. Beginning with the trivial case of electrostatic accelerators, the synchronization condition is explained for a number of driven accelerators like Alvarez linacs, cyclotrons and finally synchrotrons and storage rings, where it plays a crucial role. In the case of the latter, the principle of phase focusing is motivated qualitatively as well as on a mathematically more correct level and the problem of operation below and above the transition energy is discussed. Throughout, the main emphasis is more on physical understanding rather than on a mathematically rigorous treatment

  3. Introduction to Longitudinal Beam Dynamics

    CERN Document Server

    Holzer, B J

    2014-01-01

    This chapter gives an overview of the longitudinal dynamics of the particles in an accelerator and, closely related to that, the issue of synchronization between the particles and the accelerating field. Beginning with the trivial case of electrostatic accelerators, the synchronization condition is explained for a number of driven accelerators like Alvarez linacs, cyclotrons and finally synchrotrons and storage rings, where it plays a crucial role. In the case of the latter, the principle of phase focusing is motivated qualitatively as well as on a mathematically more correct level and the problem of operation below and above the transition energy is discussed. Throughout, the main emphasis is more on physical understanding rather than on a mathematically rigorous treatment.

  4. Introduction to Longitudinal Beam Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Holzer, B J [European Organization for Nuclear Research, Geneva (Switzerland)

    2014-07-01

    This chapter gives an overview of the longitudinal dynamics of the particles in an accelerator and, closely related to that, the issue of synchronization between the particles and the accelerating field. Beginning with the trivial case of electrostatic accelerators, the synchronization condition is explained for a number of driven accelerators like Alvarez linacs, cyclotrons and finally synchrotrons and storage rings, where it plays a crucial role. In the case of the latter, the principle of phase focusing is motivated qualitatively as well as on a mathematically more correct level and the problem of operation below and above the transition energy is discussed. Throughout, the main emphasis is more on physical understanding rather than on a mathematically rigorous treatment.

  5. College Women's Female Friendships: A Longitudinal View

    Science.gov (United States)

    Aleman, Ana M. Martinez

    2010-01-01

    This article presents a longitudinal qualitative study of the cognitive value of female friendships formed in college and seeks to appraise the meaning of the phenomenon for the participants. To grasp the temporal effects of the longitudinal data in this study, the author examines and assesses the relevant developmental literature, particularly…

  6. Total Survey Error for Longitudinal Surveys

    NARCIS (Netherlands)

    Lynn, Peter; Lugtig, P.J.

    2016-01-01

    This article describes the application of the total survey error paradigm to longitudinal surveys. Several aspects of survey error, and of the interactions between different types of error, are distinct in the longitudinal survey context. Furthermore, error trade-off decisions in survey design and

  7. Longitudinal research and data collection in primary care.

    NARCIS (Netherlands)

    Weel, C. van

    2005-01-01

    PURPOSE: This article reviews examples of and experience with longitudinal research in family medicine. The objective is to use this empirical information to formulate recommendations for improving longitudinal research. METHODS: The article discusses 3 longitudinal studies from the Nijmegen

  8. Transverse and Longitudinal proximity effect

    Science.gov (United States)

    Jalan, Pryianka; Chand, Hum; Srianand, Raghunathan

    2018-04-01

    With close pairs (˜1.5arcmin) of quasars (QSOs), absorption in the spectra of a background quasar in the vicinity of a foreground quasar can be used to study the environment of the latter quasar at kpc-Mpc scales. For this we used a sample of 205 quasar pairs from the Sloan Digital Sky-Survey Data Release 12 (SDSS DR12) in the redshift range of 2.5 to 3.5 by studying their H I Ly-α absorption. We study the environment of QSOs both in the longitudinal as well as in the transverse direction by carrying out a statistical comparison of the Ly-α absorption lines in the quasar vicinity to that of the absorption lines caused by the inter-galactic medium (IGM). This comparison was done with IGM, matched in absorption redshift and signal-to-noise ratio (SNR) to that of the proximity region. In contrast to the measurements along the line-of-sight, the regions transverse to the quasars exhibit enhanced H I Ly-α absorption. This discrepancy can either be interpreted as due to an anisotropic emission from the quasars or as a consequence of their finite lifetime.

  9. An alternative longitudinal polarization scheme for tristan

    International Nuclear Information System (INIS)

    Chao, A.W.; Yokoya, Kaoru.

    1981-07-01

    For electron storage rings general conditions are derived to get a high level longitudinal polarization and a possible design of the experimental insertion for TRISTAN e-p collider is presented. (author)

  10. Longitudinal beam dynamics at transition crossing

    Energy Technology Data Exchange (ETDEWEB)

    Bogacz, S.A.

    1991-11-01

    A brief outline of the longitudinal single particle dynamics at transition is presented in terms of phase-space mappings. Simple quantitative prediction about the phase-space dilution is made. More realistic simulation (ESME) of the transition crossing is carried out (including various collective and single particle effects contributing to the longitudinal emittance blow up). The simulation takes into account the longitudinal space-charge force (bunch length oscillation), the transverse space-charge (the Umstaetter effect) and finally the dispersion of the momentum compaction factor (the Johnsen effect). As a result of this simulation one can separate relative strengths of the above mechanisms and study their individual effects on the longitudinal phase-space evolution, especially filamentation of the bunch and formation of a galaxy-like'' pattern. 7 refs., 2 figs.

  11. Energy dissipation by a longitudinal Raman process

    International Nuclear Information System (INIS)

    Fano, U.; Inokuti, Mitio

    1994-01-01

    The concept of a longitudinal Raman process is introduced to encompass the indirect transmission of energy from slow electrons to nuclei through the reversible polarization of surrounding electrons. Experimental approaches are sought to assess this process quantitatively

  12. Multilevel Cross-Dependent Binary Longitudinal Data

    KAUST Repository

    Serban, Nicoleta; Staicu, Ana-Maria; Carroll, Raymond J.

    2013-01-01

    processes describing the within- and between-variability, and describing the cross-dependence of the repeated longitudinal measurements. We estimate the model components without employing mixed-effects modeling but assuming an approximation to the logistic

  13. Longitudinal and transverse wake potentials in SLAC

    International Nuclear Information System (INIS)

    Bane, K.; Wilson, P.

    1980-01-01

    In a machine with short bunches of high peak currents, such as the SLAC collider, one needs to know the longitudinal wake potential, for the higher mode losses, and the transverse wake potential, since, for bunches passing slightly off axis, the induced transverse forces will tend to cause beam break up. The longitudinal and transverse wakes of the SLAC structure presented here, were calculated by computer using the modal method, and including an analytic extension for higher modes. (Auth.)

  14. Longitudinal Risk Factors for Cyberbullying in Adolescence

    OpenAIRE

    Sticca, Fabio; Ruggieri, Sabrina; Alsaker, Françoise; Perren, Sonja

    2013-01-01

    Cyberbullying has emerged as a new form of antisocial behaviour in the context of online communication over the last decade. The present study investigates potential longitudinal risk factors for cyberbullying. A total of 835 Swiss seventh graders participated in a short-term longitudinal study (two assessments 6 months apart). Students reported on the frequency of cyberbullying, traditional bullying, rule-breaking behaviour, cybervictimisation, traditional victimisation, and frequency of onl...

  15. Nonlinear longitudinal dynamics studies at the ALS

    International Nuclear Information System (INIS)

    Byrd, J.M.; Cheng, W.-H.; De Santis, S.; Li, D.; Stupakov, G.; Zimmermann, F.

    1999-01-01

    We present a summary of results for a variety of studies of nonlinear longitudinal dynamics in the Advanced Light Source, an electron storage ring. These include observation of decoherence at injection, decay of an injected beam, forced synchrotron oscillations and diffusion from one bunch to the next. All of the measurements were made using a dual-scan streak camera which allowed the real-time observation of the longitudinal distribution of the electron beam

  16. Longitudinal fluctuations and decorrelation of anisotropic flow

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Long-Gang [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Petersen, Hannah [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Qin, Guang-You [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Roy, Victor [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Wang, Xin-Nian [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division MS70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-12-15

    We investigate the decorrelation of 2nd and 3rd order anisotropic flow for charged particles in two different pseudo rapidity (η) windows by varying the pseudo rapidity gap, in an event-by-event (3+1)D ideal hydrodynamic model, with fluctuating initial conditions from A Multi-Phase Transport (AMPT) model. We visualize the parton distribution at initial state for Pb+Pb collisions at LHC and Au+Au collisions at RHIC, and demonstrate the longitudinal fluctuations originating from the asymmetry between forward and backward going participants, the fluctuations of the string length and the fluctuations due to finite number of partons at different beam energies. The decorrelation of anisotropic flow of final hadrons with large η gaps is found to originate from the spatial decorrelation along the longitudinal direction in the AMPT initial conditions through hydrodynamic evolution. The agreement between our results and recent CMS data in most centralities suggests that the string-like mechanism of initial parton production in AMPT model captures the initial longitudinal fluctuation that is responsible for the measured decorrelation of anisotropic flow in Pb+Pb collisions at LHC. Our predictions for Au+Au collisions at the highest RHIC energy show stronger longitudinal decorrelation than at LHC, indicating larger longitudinal fluctuations at lower beam energies.

  17. Study of CSR longitudinal bunch compression cavity

    International Nuclear Information System (INIS)

    Yin Dayu; Li Peng; Liu Yong; Xie Qingchun

    2009-01-01

    The scheme of longitudinal bunch compression cavity for the Cooling Storage Ring (CSR)is an important issue. Plasma physics experiments require high density heavy ion beam and short pulsed bunch,which can be produced by non-adiabatic compression of bunch implemented by a fast compression with 90 degree rotation in the longitudinal phase space. The phase space rotation in fast compression is initiated by a fast jump of the RF-voltage amplitude. For this purpose, the CSR longitudinal bunch compression cavity, loaded with FINEMET-FT-1M is studied and simulated with MAFIA code. In this paper, the CSR longitudinal bunch compression cavity is simulated and the initial bunch length of 238 U 72+ with 250 MeV/u will be compressed from 200 ns to 50 ns.The construction and RF properties of the CSR longitudinal bunch compression cavity are simulated and calculated also with MAFIA code. The operation frequency of the cavity is 1.15 MHz with peak voltage of 80 kV, and the cavity can be used to compress heavy ions in the CSR. (authors)

  18. Longitudinal Electroproduction of Charged Pions from

    International Nuclear Information System (INIS)

    David Gaskell; Abdellah Ahmidouch; Pawel Ambrozewicz; H. Anklin; John Arrington; K. Assamagan; Steven Avery; Kevin Bailey; Oliver K. Baker; Shelton Beedoe; Elizabeth Beise; Herbert Breuer; D. S. Brown; Roger Carlini; Jinseok Cha; Nicholas Chant; Anthony Cowley; Samuel Danagoulian; D. De Schepper; Jim Dunne; Dipangkar Dutta; Rolf Ent; Liping Gan; Ashot Gasparian; Donald Geesaman; Ron Gilman; Charles Glashausser; Paul Gueye; M. Harvey; O. Hashimoto; Wendy Hinton; G. Hofman; Ceasar Jackson; Hal Jackson; Cynthia Keppel; Ed Kinney; Doug Koltenuk; G. Kyle; Allison Lung; David Mack; D. McKee; Joseph Mitchell; Hamlet Mkrtchyan; B. Mueller; Gabriel Niculescu; Ioana Niculescu; Tom O'Neill; V. Papavassiliou; Dave Potterveld; Juerg Reinhold; Philip Roos; Reyad Sawafta; Ralph Segel; Stepan Stepanyan; Vardan Tadevosyan; T. Takahashi; Liguang Tang; B. Terburg; D. Van Westrum; J. Volmer; T. P. Welch; Stephen Wood; Lulin Yuan; Ben Zeidman; Beni Zihlmann

    2001-01-01

    Separated longitudinal and transverse cross sections for charged pion electroproduction from 1 H, 2 H, and 3 He were measured at Q 2 = 0.4 (GeV/c) 2 for two values of the invariant mass, (bar W) = 1.15 GeV and (bar W) = 1.60 GeV, in a search for a mass dependence which would signal the effect of nuclear pions. This is the first such study that includes recoil momenta significantly above the Fermi surface. The longitudinal cross section, if dominated by the pion-pole process, should be sensitive to nuclear pion currents. Comparisons of the longitudinal cross section target ratios to a quasifree calculation reveal a significant suppression in 3> He at (bar W) = 1.60 GeV. The (bar W) = 1.15 GeV results are consistent with simple estimates of the effect of nuclear pion currents, but are also consistent with pure quasifree production

  19. Longitudinal magnetoresistance and magnototermopower in Bi nanowires

    International Nuclear Information System (INIS)

    Para, G.

    2011-01-01

    Full text: The galvanomagnetic effect of single crystals Bi nanowires have been studied in longitudinal magnetic fields up to 14 T. The influence of diameters, temperature and deformation extension on the longitudinal magnetoresistance and magnetotermopower (H||I, H||ΔT) of bismuth nanowires is studied. Elastic deformation measurements were conducted at maximum relative elongation 2 %. For the first time have been investigated the magnetotermopower of Bi nanowires with d=45 nm. Essentially non monotonic dependence H max on temperature in longitudinal thermopower in wires with d=45-60 nm is found out. Such difference in behavior of maximum on R(H) and on α(H) in wires with d<100nm says that the behavior of resistance is caused by other mechanism, then thermopower. (author)

  20. Magnetic field of longitudinal gradient bend

    Science.gov (United States)

    Aiba, Masamitsu; Böge, Michael; Ehrlichman, Michael; Streun, Andreas

    2018-06-01

    The longitudinal gradient bend is an effective method for reducing the natural emittance in light sources. It is, however, not a common element. We have analyzed its magnetic field and derived a set of formulae. Based on the derivation, we discuss how to model the longitudinal gradient bend in accelerator codes that are used for designing electron storage rings. Strengths of multipole components can also be evaluated from the formulae, and we investigate the impact of higher order multipole components in a very low emittance lattice.

  1. Simulations of longitudinally pumped dye laser amplifier

    International Nuclear Information System (INIS)

    Takehisa, Kiwamu; Takemori, Satoshi

    1995-01-01

    Simulations of a copper laser pumped dye laser amplifier and new designs of the longitudinally pumped dye laser amplifier are presented. The simulations take the consideration of the amplified spontaneous emission (ASE). The new designs utilize a center-hole reflector instead of a dichroic mirror. The simulation results indicate that the poor spatial overlap between the pump beam and the dye beam in the transverse pumping not only reduces the laser output power, but also generates ASE strongly. The results also indicate that the longitudinal pumping is as efficient as the transverse pumping. (author)

  2. Longitudinal tibial epiphyseal bracket in Nievergelt syndrome

    International Nuclear Information System (INIS)

    Burnstein, M.I.; De Smet, A.A.; Breed, A.L.; Thomas, J.R.; Hafez, G.R.

    1989-01-01

    A patient is described with lower extremity mesomelic dwarfism associated with bilateral congenital elbow, hip, and knee dislocations. Rhomboid-shaped tibiae and delayed ossification of the primary fibular ossification centers were demonstrated at birth. Plain films and magnetic resonance imaging revealed that the tibial deformities were due to the presence of longitudinal epiphyseal brackets. These brackets were observed at surgery and confirmed histologically. Recognition of the longitudinal epiphyseal bracket and its relationship to the tibial deformities seen in this patient with Nievergelt syndrome is important for planning surgical treatment. (orig.)

  3. Longitudinal tibial epiphyseal bracket in Nievergelt syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Burnstein, M.I.; De Smet, A.A.; Breed, A.L.; Thomas, J.R.; Hafez, G.R.

    1989-04-01

    A patient is described with lower extremity mesomelic dwarfism associated with bilateral congenital elbow, hip, and knee dislocations. Rhomboid-shaped tibiae and delayed ossification of the primary fibular ossification centers were demonstrated at birth. Plain films and magnetic resonance imaging revealed that the tibial deformities were due to the presence of longitudinal epiphyseal brackets. These brackets were observed at surgery and confirmed histologically. Recognition of the longitudinal epiphyseal bracket and its relationship to the tibial deformities seen in this patient with Nievergelt syndrome is important for planning surgical treatment. (orig.).

  4. Longitudinal and bulk viscosities of expanded rubidium

    International Nuclear Information System (INIS)

    Zaheri, Ali Hossein Mohammad; Srivastava, Sunita; Tankeshwar, K

    2003-01-01

    First three non-vanishing sum rules for the bulk and longitudinal stress auto-correlation functions have been evaluated for liquid Rb at six thermodynamic states along the liquid-vapour coexistence curve. The Mori memory function formalism and the frequency sum rules have been used to calculate bulk and longitudinal viscosities. The results thus obtained for the ratio of bulk viscosity to shear viscosity have been compared with experimental and other theoretical predictions wherever available. The values of the bulk viscosity have been found to be more than the corresponding values of the shear viscosity for all six thermodynamic states investigated here

  5. Collaborative Knowledge-Building: A Longitudinal Study

    Science.gov (United States)

    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…

  6. Are Sibling Relationships Protective? A Longitudinal Study

    Science.gov (United States)

    Gass, Krista; Jenkins, Jennifer; Dunn, Judy

    2007-01-01

    Background: Although the protective effects of familial and parental support have been studied extensively in the child psychopathology literature, few studies have explored the protective quality of positive sibling relationships. Methods: A two-wave longitudinal design was used to examine the protective effect of positive sibling relationships…

  7. Advection models of longitudinal dispersion in rivers

    NARCIS (Netherlands)

    Kranenburg, C.

    1996-01-01

    A derivation is presented of a general cross-section averaged model of longitudinal dispersion, which is based on the notion of the advection of tracer particles. Particle displacement length and particle travel time are conceived as stochastic variables, and a joint probability density function is

  8. The Czech longitudinal study of optimal development

    Czech Academy of Sciences Publication Activity Database

    Kebza, V.; Šolcová, Iva; Kodl, M.; Kernová, V.

    2012-01-01

    Roč. 47, Suppl. 1 (2012), s. 266-266 ISSN 0020-7594. [International Congress of Psychology /30./. 22.07.2012-27.07.2012, Cape Town] R&D Projects: GA ČR GAP407/10/2410 Institutional support: RVO:68081740 Keywords : optimal development * Prague longitudinal study Subject RIV: AN - Psychology

  9. Longitudinal myelitis associated with yellow fever vaccination.

    Science.gov (United States)

    Chaves, M; Riccio, P; Patrucco, L; Rojas, J I; Cristiano, E

    2009-07-01

    Severe adverse reaction to yellow fever (YF) vaccine includes the yellow fever vaccine-associated neurotropic disease. This terminology includes postvaccinal encephalitis, acute disseminated encephalomyelitis, and Guillain-Barré syndrome. The objective of this communication is to report a patient who received a YF vaccine in Argentina and subsequently developed longitudinal myelitis with a symptom that had previously gone unreported in the literature. A 56-year-old man began with progressive paraparesia, urinary retention, and constipation 48 h previous to admission. The patient received YF vaccine 45 days prior to the onset of the symptoms. There was no history of other immunization or relevant condition. MR of the spine showed longitudinal intramedullary hyperintense signal (D5-12) without gadolinium enhancement. A high concentration of YFV-specific IgM vaccine antibody was found in the cerebrospinal fluid (CSF). Serological tests for other flavivirus were negative. A diagnosis of longitudinal myelitis without encephalitis associated with YF vaccine was performed and symptoms improved 5 days later. This is the first report dealing with longitudinal myelitis as a serious adverse event associated with YF vaccination in which confirmation of the presence of antibodies in CSF was found. To date, it is also the first report with serological confirmation in Argentina and in South America. We consider that the present investigation will raise awareness in the region in the reporting of adverse events related to YF vaccine and improve our knowledge of adverse reactions to the vaccine.

  10. Longitudinal Predictors of High School Completion

    Science.gov (United States)

    Barry, Melissa; Reschly, Amy L.

    2012-01-01

    This longitudinal study examined predictors of dropout assessed in elementary school. Student demographic data, achievement, attendance, and ratings of behavior from the Behavior Assessment System for Children were used to predict dropout and completion. Two models, which varied on student sex and race, predicted dropout at rates ranging from 75%…

  11. The Merits of Using Longitudinal Mediation

    Science.gov (United States)

    Jose, Paul E.

    2016-01-01

    Many of the mediation analyses reported in the literature are based on concurrent or single-occasion data sets. The 2 overarching themes of the present article are: Results of concurrent mediations are inherently ambiguous, and researchers would be wise to conduct mediations on longitudinal data sets instead. An example included here demonstrates…

  12. Statistical Power in Longitudinal Network Studies

    NARCIS (Netherlands)

    Stadtfeld, Christoph; Snijders, Tom A. B.; Steglich, Christian; van Duijn, Marijtje

    2018-01-01

    Longitudinal social network studies may easily suffer from a lack of statistical power. This is the case in particular for studies that simultaneously investigate change of network ties and change of nodal attributes. Such selection and influence studies have become increasingly popular due to the

  13. Development of longitudinally excited CO2 laser

    Science.gov (United States)

    Masroon, N. S.; Tanaka, M.; Tei, M.; Uno, K.; Tsuyama, M.; Nakano, H.

    2018-05-01

    Simple, compact, and affordable discharged-pumped CO2 laser controlled by a fast high voltage solid state switch has been developed. In this study, longitudinal excitation scheme has been adapted for simple configuration. In the longitudinal excitation scheme, the discharge is produced along the direction of the laser axis, and the electrodes are well separated with a small discharge cross-section. Triggered spark gap switch is usually used to switch out the high voltage because of simple and low cost. However, the triggered spark gap operates in the arc mode and suffer from recovery problem causing a short life time and low efficiency for high repetition rate operation. As a result, there is now considerable interest in replacing triggered spark gap switch with solid state switches. Solid state switches have significant advantages compared to triggered spark gap switch which include longer service lifetime, low cost and stable high trigger pulse. We have developed simple and low cost fast high voltage solid state switch that consists of series connected-MOSFETs. It has been installed to the longitudinally excited CO2 laser to realize the gap switch less operation. Characteristics of laser oscillation by varying the discharge length, charging voltage, capacitance and gas pressure have been evaluated. Longer discharge length produce high power of laser oscillation. Optimum charging voltage and gas pressure were existed for longitudinally excited CO2 laser.

  14. Longitudinal bulk a coustic mass sensor

    DEFF Research Database (Denmark)

    Hales, Jan Harry; Teva, Jordi; Boisen, Anja

    2009-01-01

    Design, fabrication and characterization, in terms of mass sensitivity, is presented for a polycrystalline silicon longitudinal bulk acoustic cantilever. The device is operated in air at 51 MHz, resulting in a mass sensitivity of 100 HZ/fg (1 fg = 10{su−15 g). The initial characterization is cond...

  15. Heat production: Longitudinal versus torsional phacoemulsification.

    Science.gov (United States)

    Han, Young Keun; Miller, Kevin M

    2009-10-01

    To compare the heat production of longitudinal versus torsional phacoemulsification under strict laboratory test conditions. Department of Ophthalmology, David Geffen School of Medicine at UCLA, and Jules Stein Eye Institute, Los Angeles, California, USA. Two Infiniti phacoemulsification handpieces were inserted into silicone test chambers filled with a balanced salt solution and imaged serially using a thermal camera. Incision compression was simulated by suspending 25.3 g weights from the silicone chambers. To simulate occlusion of the phacoemulsification tip, the aspiration line was clamped. Peak temperatures were measured 0, 10, 30, 60, and 120 seconds after the commencement of continuous ultrasound power. The 2 handpieces, operating exclusively in longitudinal or torsional modes, were compared 3 ways: (1) using the same power displayed on the instrument console, (2) using identical stroke lengths, and (3) using the same applied energy, a product of stroke length and frequency. For all 3 comparisons, torsional phacoemulsification resulted in lower temperatures at each time point. At the same displayed power setting, the scenario most familiar to cataract surgeons, longitudinal phacoemulsification elevated temperatures up to 41.5 degrees C more than torsional phacoemulsification. Torsional phacoemulsification generated less heat than longitudinal phacoemulsification in all 3 comparison tests. Lower operating temperatures indicate lower heat generation within the same volume of fluid, and this may provide additional thermal protection during cataract surgery.

  16. Burnout development among dentists : a longitudinal study

    NARCIS (Netherlands)

    te Brake, H.; Smits, N.; Wicherts, J.M.; Gorter, R.C.; Hoogstraten, J.

    2008-01-01

    Knowledge on the development of burnout among dentists is important for purposes of prevention and intervention. Using a two-wave longitudinal design, this study examined the chronological sequence of the three dimensions of the Maslach Burnout Inventory: emotional exhaustion; depersonalization; and

  17. Boosted Multivariate Trees for Longitudinal Data

    Science.gov (United States)

    Pande, Amol; Li, Liang; Rajeswaran, Jeevanantham; Ehrlinger, John; Kogalur, Udaya B.; Blackstone, Eugene H.; Ishwaran, Hemant

    2017-01-01

    Machine learning methods provide a powerful approach for analyzing longitudinal data in which repeated measurements are observed for a subject over time. We boost multivariate trees to fit a novel flexible semi-nonparametric marginal model for longitudinal data. In this model, features are assumed to be nonparametric, while feature-time interactions are modeled semi-nonparametrically utilizing P-splines with estimated smoothing parameter. In order to avoid overfitting, we describe a relatively simple in sample cross-validation method which can be used to estimate the optimal boosting iteration and which has the surprising added benefit of stabilizing certain parameter estimates. Our new multivariate tree boosting method is shown to be highly flexible, robust to covariance misspecification and unbalanced designs, and resistant to overfitting in high dimensions. Feature selection can be used to identify important features and feature-time interactions. An application to longitudinal data of forced 1-second lung expiratory volume (FEV1) for lung transplant patients identifies an important feature-time interaction and illustrates the ease with which our method can find complex relationships in longitudinal data. PMID:29249866

  18. Teaching Technology Longitudinally to Virtual Children

    Science.gov (United States)

    Matthews, Lynley

    2010-01-01

    Children of Generation Y are entering our schooling system. These children have always known instant communication and the internet. They possess basic skills in using technology, but they still need to develop a deeper understanding of technology. Teaching longitudinally will increase the learner's confidence and develop a deeper understanding.…

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

    Directory of Open Access Journals (Sweden)

    Rebecca Lubitz

    2015-12-01

    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.

  20. Variable selection and estimation for longitudinal survey data

    KAUST Repository

    Wang, Li; Wang, Suojin; Wang, Guannan

    2014-01-01

    There is wide interest in studying longitudinal surveys where sample subjects are observed successively over time. Longitudinal surveys have been used in many areas today, for example, in the health and social sciences, to explore relationships

  1. 46 CFR 154.176 - Longitudinal contiguous hull structure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Longitudinal contiguous hull structure. 154.176 Section... Equipment Hull Structure § 154.176 Longitudinal contiguous hull structure. (a) The longitudinal contiguous hull structure of a vessel having cargo containment systems without secondary barriers must meet the...

  2. Ring RF and longitudinal dynamics in the SNS

    International Nuclear Information System (INIS)

    Blaskiewicz, M.; Brennan, J.M.; Brodowski, J.; Delong, J.; Meth, M.; Onillon, E.; Zaltsman, A.

    2000-01-01

    Average beam currents of 40 A will be present in the Spallation Neutron Source. Even though the entire cycle time is only one synchrotron oscillation the longitudinal phase space determines peak beam current and momentum spread. Both factors play a role in space charge and instability dynamics. Longitudinal simulations with beam loading and longitudinal space charge have been done in the design phase

  3. Existence of longitudinal waves in pre-stressed anisotropic elastic ...

    Indian Academy of Sciences (India)

    waves is truly longitudinal. Longitudinal wave in an anisotropic elastic medium is defined as the wave motion in which the particle motion (i.e., the. Keywords. General anisotropy; elastic stiffness; pre-stress; group velocity; ray direction; longitudinal waves; polarization. J. Earth Syst. Sci. 118, No. 6, December 2009, pp. 677– ...

  4. Evaluation of longitudinal loading of tank trains during motion in longitudinal changes of gradient

    Directory of Open Access Journals (Sweden)

    S.V. Myamlin

    2013-06-01

    Full Text Available Purpose. To research the tank train longitudinal loading during motion by track sections with changes of gradient. The trains of different length that consist of bogie tank wagons should be examined. Influence of cargo type on longitudinal loading of train during motion in concave section of track should be evaluated. Methodology. The level of the largest longitudinal forces was estimated by mathematical simulation. It was assumed that change of gradient is formed by two grades with baffle platforms, length 50 meters, so that the algebraic difference of limiting grades vary from 10‰ to 40‰, pitch 10‰. The initial speeds were 40, 60, 80, 100, 120 km/h. For evaluation of the longitudinal loading the regulating braking and motion "by coasting" was considered. For evaluation of buffing loads the entry to the concave gradient change of expanded train is considered, and in order to determine the quasi-static forces the compressed train is considered. Findings. As a result of calculations the dependencies of maximal longitudinal forces in the trains on the cargo type, the algebraic difference of the grades, the number of tank wagons, the initial speed, motion modes, and initial gaps condition in the train were obtained. Originality. The longitudinal loading of freight cars of different length formed by the similar bogie tank wagons with one locomotive was obtained. The locomotive is placed in the train head during motion in concave track sections with various algebraic difference of the grades "on coasting" and during the regulating braking mode. The obtained results can be used for parameters standardization of profile elevation of the track. Practical value. The obtained results show that during operation of tank trains on track sections of complex breakage the most dangerous is regulating braking of preliminary compressed trains during entering on concave parts of track. Level of the greatest buffing and quasi-static longitudinal forces is

  5. Longitudinal Control for Mengshi Autonomous Vehicle via Cloud Model

    Science.gov (United States)

    Gao, H. B.; Zhang, X. Y.; Li, D. Y.; Liu, Y. C.

    2018-03-01

    Dynamic robustness and stability control is a requirement for self-driving of autonomous vehicle. Longitudinal control method of autonomous is a key technique which has drawn the attention of industry and academe. In this paper, we present a longitudinal control algorithm based on cloud model for Mengshi autonomous vehicle to ensure the dynamic stability and tracking performance of Mengshi autonomous vehicle. An experiments is applied to test the implementation of the longitudinal control algorithm. Empirical results show that if the longitudinal control algorithm based Gauss cloud model are applied to calculate the acceleration, and the vehicles drive at different speeds, a stable longitudinal control effect is achieved.

  6. Longitudinal momentum distributions in transverse coordinate space

    International Nuclear Information System (INIS)

    Kumar, Narinder; Mondal, Chandan

    2016-01-01

    In the present work, we study the longitudinal momentum distributions in the transverse coordinate space in a light-front quark-diquark model inspired by soft-wall AdS/QCD. We take the phenomenological light-front quark-diquark model proposed by Gutsche et. al. In this model, the light-front wave functions (LFWFs) for the proton are constructed from the two particle wave functions obtained in soft-wall AdS/QCD

  7. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Multimedia

    Oeftiger, Adrian; Rumolo, Giovanni

    2016-01-01

    Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  8. Longitudinal profile of channels cut by springs

    OpenAIRE

    Devauchelle , O.; PETROFF , A. P.; LOBKOVSKY , A. E.; Rothman , D. H.

    2011-01-01

    International audience; We propose a simple theory for the longitudinal profile of channels incised by groundwater flow. The aquifer surrounding the stream is represented in two dimensions through Darcy's law and the Dupuit approximation. The model is based on the assumption that, everywhere in the stream, the shear stress exerted on the sediment by the flow is close to the minimal intensity required to displace a sand grain. Because of the coupling of the stream discharge with the water tabl...

  9. Longitudinal Schottky noise of intense beam

    International Nuclear Information System (INIS)

    Pestrikov, D.V.

    1990-01-01

    Some phenomena, which can be observed in the longitudinal Schottky spectra in storage ring with electron cooling as well as some technical details, which can be useful for the models of fitting are reviewed. Results shows that both the spectra and the power of the Schottky noise of the coasting beam are very sensitive to collective behaviour of the beam. This can be used for fitting of Schottky noise measurements and recalculation of beam parameters, parameters of cooling device. 9 refs.; 4 figs

  10. Marginal longitudinal semiparametric regression via penalized splines

    KAUST Repository

    Al Kadiri, M.

    2010-08-01

    We study the marginal longitudinal nonparametric regression problem and some of its semiparametric extensions. We point out that, while several elaborate proposals for efficient estimation have been proposed, a relative simple and straightforward one, based on penalized splines, has not. After describing our approach, we then explain how Gibbs sampling and the BUGS software can be used to achieve quick and effective implementation. Illustrations are provided for nonparametric regression and additive models.

  11. Marginal longitudinal semiparametric regression via penalized splines

    KAUST Repository

    Al Kadiri, M.; Carroll, R.J.; Wand, M.P.

    2010-01-01

    We study the marginal longitudinal nonparametric regression problem and some of its semiparametric extensions. We point out that, while several elaborate proposals for efficient estimation have been proposed, a relative simple and straightforward one, based on penalized splines, has not. After describing our approach, we then explain how Gibbs sampling and the BUGS software can be used to achieve quick and effective implementation. Illustrations are provided for nonparametric regression and additive models.

  12. Longitudinal ultrasonic waves dispersion in bars

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2001-01-01

    The exhibition intends to review some aspects of the propagation of the longitudinal ultrasonic pulses shortly in bars of traverse section uniform.Aspects they are part of the denominated geometric dispersion of the pulses.This phenomenon It can present like an additional complication in the ultrasonic essay of low frequency of thin pieces in structures and machines but takes place former ex professed in some applications of the wave guides been accustomed to in the prosecution of signs

  13. RADON reconstruction in longitudinal phase space

    International Nuclear Information System (INIS)

    Mane, V.; Peggs, S.; Wei, J.

    1997-01-01

    Longitudinal particle motion in circular accelerators is typically monitoring by one dimensional (1-D) profiles. Adiabatic particle motion in two dimensional (2-D) phase space can be reconstructed with tomographic techniques, using 1-D profiles. A computer program RADON has been developed in C++ to process digitized mountain range data and perform the phase space reconstruction for the AGS, and later for Relativistic Heavy Ion Collider (RHIC)

  14. Substance use and motivation: a longitudinal perspective.

    Science.gov (United States)

    Korcha, Rachael A; Polcin, Douglas L; Bond, Jason C; Lapp, William M; Galloway, Gantt

    2011-01-01

    Motivation to change substance use behavior is an important component of the recovery process that has usually been studied at entry into treatment. Less studied, but equally important, is the measurement of motivation over time and the role motivation plays in subsequent substance use. The present study sought to examine longitudinal motivation toward sobriety among residents of sober living houses. Sober living residents (n = 167) were followed at 6-month intervals over an 18-month period and assessed for motivation and substance use outcomes at each study interview. Motivation was measured using the costs and benefits subscales of the Alcohol and Drug Consequences Questionnaire (ADCQ) and substance use outcomes included the Addiction Severity Index (ASI) alcohol scale, ASI drug scale, and peak density of substance use (number of days of most use in a month). Participants reported higher benefits than costs of sobriety or cutting down substance use at every study time point. Using lagged generalized estimating equation models, the ADCQ costs predicted increased severity for alcohol, drugs, and peak density, whereas the benefits subscale predicted decreased drug and peak density. Longitudinal measurement of motivation can be a useful clinical tool to understand later substance use problems. Given the mixed findings from prior studies on the effects of baseline motivation, a shift toward examining longitudinal measures of motivation at proximal and temporal intervals is indicated.

  15. Multilevel Cross-Dependent Binary Longitudinal Data

    KAUST Repository

    Serban, Nicoleta

    2013-10-16

    We provide insights into new methodology for the analysis of multilevel binary data observed longitudinally, when the repeated longitudinal measurements are correlated. The proposed model is logistic functional regression conditioned on three latent processes describing the within- and between-variability, and describing the cross-dependence of the repeated longitudinal measurements. We estimate the model components without employing mixed-effects modeling but assuming an approximation to the logistic link function. The primary objectives of this article are to highlight the challenges in the estimation of the model components, to compare two approximations to the logistic regression function, linear and exponential, and to discuss their advantages and limitations. The linear approximation is computationally efficient whereas the exponential approximation applies for rare events functional data. Our methods are inspired by and applied to a scientific experiment on spectral backscatter from long range infrared light detection and ranging (LIDAR) data. The models are general and relevant to many new binary functional data sets, with or without dependence between repeated functional measurements.

  16. Operation of PEP longitudinal feedback system

    International Nuclear Information System (INIS)

    Allen, M.A.; Karvonen, L.G.; McConnell, R.A.; Schwarz, H.

    1981-03-01

    In order to suppress longitudinal coupled-bunch oscillations which might limit the capabilities of PEP, the 18 GeV e + e - storage ring at SLAC, a longitudinal feedback system is utilized. A frequency domain feedback system was chosen with the frequency spectrum of the stored beam being sampled close to a symmetry point in the ring where the feedback cavity itself is also located. The symmetry point chosen is symmetry point 5 which lies half-way between interaction regions 4 and 6. The system has been installed in PEP and is now operational. However, at stored currents up to the maximum stored in PEP to date at 14.5 GeV (approximately 40 mA in 6 bunches), the ring has been stable to all modes of longitudinal coupled-bunch oscillations both barycentric and the other fundamental modes. By deliberately detuning the main accelerating cavities, small multibunch oscillations can be introduced which, in turn, can be damped by the feedback system. Under optimized beam conditions the feedback system could be adjusted to positive feedback and excite oscillations with relatively small power to the feedback cavity. This will be described along with other details of the system

  17. Nucleon Spin Structure: Longitudinal and Transverse

    International Nuclear Information System (INIS)

    Chen, Jian-Ping

    2011-01-01

    Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinal polarized parton (quark and gluon) distributions in the nucleon. It has becoming clear that transverse spin and transverse momentum dependent distributions (TMDs) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction. The transverse spin structure and the TMDs are the subject of increasingly intense theoretical and experimental study recently. With a high luminosity electron beam facility, JLab has played a major role in the worldwide effort to study both the longitudinal and transverse spin structure. Highlights of recent results will be presented. With 12-GeV energy upgrade, JLab will provide the most precise measurements in the valence quark region to close a chapter in longitudinal spin study. JLab will also perform a multi-dimensional mapping of the transverse spin structure and TMDs in the valence quark region through Semi-Inclusive DIS (SIDIS) experiments, providing a 3-d partonic picture of the nucleon in momentum space and extracting the u and d quark tensor charges of the nucleon. The precision mapping of TMDs will also allow a detailed study of the quark orbital motion and its dynamics.

  18. Longitudinal analysis of mouse SDOCT volumes

    Science.gov (United States)

    Antony, Bhavna J.; Carass, Aaron; Lang, Andrew; Kim, Byung-Jin; Zack, Donald J.; Prince, Jerry L.

    2017-03-01

    Spectral-domain optical coherence tomography (SDOCT), in addition to its routine clinical use in the diagnosis of ocular diseases, has begun to fund increasing use in animal studies. Animal models are frequently used to study disease mechanisms as well as to test drug efficacy. In particular, SDOCT provides the ability to study animals longitudinally and non-invasively over long periods of time. However, the lack of anatomical landmarks makes the longitudinal scan acquisition prone to inconsistencies in orientation. Here, we propose a method for the automated registration of mouse SDOCT volumes. The method begins by accurately segmenting the blood vessels and the optic nerve head region in the scans using a pixel classification approach. The segmented vessel maps from follow-up scans were registered using an iterative closest point (ICP) algorithm to the baseline scan to allow for the accurate longitudinal tracking of thickness changes. Eighteen SDOCT volumes from a light damage model study were used to train a random forest utilized in the pixel classification step. The area under the curve (AUC) in a leave-one-out study for the retinal blood vessels and the optic nerve head (ONH) was found to be 0.93 and 0.98, respectively. The complete proposed framework, the retinal vasculature segmentation and the ICP registration, was applied to a secondary set of scans obtained from a light damage model. A qualitative assessment of the registration showed no registration failures.

  19. Longitudinal study on osteoarthritis and bone metabolism

    Directory of Open Access Journals (Sweden)

    L. Postiglione

    2011-09-01

    Full Text Available Objective: The relationship between Osteoarthritis (OA and Osteoporosis (OP is not well defined due to lacking in longitudinal data, mainly regarding correlations between biochemical factors and OA incidence. Aim of this paper was to investigate the predictive value for OA incidence of bone mass variations and of selected biochemical markers in healthy women participating in a population-based longitudinal study carried out in Naples (Italy. Subjects and Methods: High completion rate (85.2% and statistically adequate sample size were obtained: 139 women (45 to 79 years of age were examined and follow up visit was performed after two years (24±2 months, following the same protocol. Patients underwent medical examination, questionnaire, anthropometric measurements, blood sampling and urine collection. Bone mineral density (BMD measurement was performed by dual energy X-ray absorptiometry (DEXA at the lumbar spine (L1-L4 and femoral neck. Radiographs of dorsal and lumbar spine in lateral view were performed at basal and at 24 months visits; a team of three experts scored radiographs using Kellegren and Lawrence grading. Results: The score was calculated for two individual radiographic features (narrowing of the joint space, presence of osteophytes and as a global score. Results show a relevant percentage, 23% up, of subjects presenting both OA and OP. In the cross-sectional study the presence of osteophytosis correlates with anthropometric variables and PTH levels. In the longitudinal study results show a correlation between serum vitamin D and delta score for osteophytosis (β=0.02 p<0.05. Conclusions: Data obtained outline the importance of further studies on the pathogenetic link between OA and bone metabolism.

  20. Resonant longitudinal Zitterbewegung in zigzag graphene nanoribbons

    KAUST Repository

    Ghosh, S.; Schwingenschlö gl, Udo; Manchon, Aurelien

    2015-01-01

    The Zitterbewegung of a wave packet in a zigzag graphene nanoribbon is theoretically investigated. The coupling between edge states and bulk states results in intriguing properties. Apart from the oscillation in position perpendicular to the direction of motion, we also observe an oscillation along the direction of propagation which is not present in semiconductor nanowires or infinite graphene sheets. We also observe a resonance of its amplitude with respect to the central momentum of the wave packet. We show here that this longitudinal Zitterbewegung is caused by the interplay between bulk and edge states, which is a unique property of a zigzag nanoribbon.

  1. Longitudinal wave ultrasonic inspection of austenitic weldments

    International Nuclear Information System (INIS)

    Gray, B.S.; Hudgell, R.J.; Seed, H.

    1980-01-01

    Successful volumetric inspection of LMFBR primary circuits, and also much of the secondary circuit, is dependent on the availability of satisfactory examination procedures for austenitic welds. Application of conventional ultrasonic techniques is hampered by the anisotropic, textured structure of the weld metal and this paper describes development work on the use of longitudinal wave techniques. In addition to confirming the dominant effects of the weld structure on ultrasound propagation some results are given of studies utilising deliberately induced defects in Manual Metal Arc Welds in 50 mm plate together with preliminary work on the inspection of narrow austenitic welds fabricated by automatic processes. (author)

  2. Resonant longitudinal Zitterbewegung in zigzag graphene nanoribbons

    KAUST Repository

    Ghosh, S.

    2015-01-08

    The Zitterbewegung of a wave packet in a zigzag graphene nanoribbon is theoretically investigated. The coupling between edge states and bulk states results in intriguing properties. Apart from the oscillation in position perpendicular to the direction of motion, we also observe an oscillation along the direction of propagation which is not present in semiconductor nanowires or infinite graphene sheets. We also observe a resonance of its amplitude with respect to the central momentum of the wave packet. We show here that this longitudinal Zitterbewegung is caused by the interplay between bulk and edge states, which is a unique property of a zigzag nanoribbon.

  3. Regional vulnerability of longitudinal cortical association connectivity

    Directory of Open Access Journals (Sweden)

    Rafael Ceschin

    2015-01-01

    Full Text Available Preterm born children with spastic diplegia type of cerebral palsy and white matter injury or periventricular leukomalacia (PVL, are known to have motor, visual and cognitive impairments. Most diffusion tensor imaging (DTI studies performed in this group have demonstrated widespread abnormalities using averaged deterministic tractography and voxel-based DTI measurements. Little is known about structural network correlates of white matter topography and reorganization in preterm cerebral palsy, despite the availability of new therapies and the need for brain imaging biomarkers. Here, we combined novel post-processing methodology of probabilistic tractography data in this preterm cohort to improve spatial and regional delineation of longitudinal cortical association tract abnormalities using an along-tract approach, and compared these data to structural DTI cortical network topology analysis. DTI images were acquired on 16 preterm children with cerebral palsy (mean age 5.6 ± 4 and 75 healthy controls (mean age 5.7 ± 3.4. Despite mean tract analysis, Tract-Based Spatial Statistics (TBSS and voxel-based morphometry (VBM demonstrating diffusely reduced fractional anisotropy (FA reduction in all white matter tracts, the along-tract analysis improved the detection of regional tract vulnerability. The along-tract map-structural network topology correlates revealed two associations: (1 reduced regional posterior–anterior gradient in FA of the longitudinal visual cortical association tracts (inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiation, posterior thalamic radiation correlated with reduced posterior–anterior gradient of intra-regional (nodal efficiency metrics with relative sparing of frontal and temporal regions; and (2 reduced regional FA within frontal–thalamic–striatal white matter pathways (anterior limb/anterior thalamic radiation, superior longitudinal fasciculus and cortical spinal tract

  4. Longitudinal emittance measurement at the ATS

    International Nuclear Information System (INIS)

    Cottingame, W.B.; Cortez, J.H.; Higgins, W.W.; Sander, O.R.; Sandoval, D.P.

    1986-01-01

    With increasing brightness, beam diagnostic techniques requiring interception of the beam become impractical. For H - particle beams, solutions for this problem based on the phenomenon of photodissociation are now being investigated at the Los Alamos National Laboratory accelerator test stand (ATS). A laser can be used to selectively neutralize portions of the beam than can be characterized after the charged particles have been swept away. We have used this technique for measuring longitudinal emittance at the output of the ATS radio-frequency quadrupole

  5. Longitudinal Diagnostics for Short Electron Beam Bunches

    Energy Technology Data Exchange (ETDEWEB)

    Loos, H.; /SLAC

    2010-06-11

    Single-pass free electron lasers require high peak currents from ultra-short electron bunches to reach saturation and an accurate measurement of bunch length and longitudinal bunch profile is necessary to control the bunch compression process from low to high beam energy. The various state-of-the-art diagnostics methods from ps to fs time scales using coherent radiation detection, RF deflection, and other techniques are presented. The use of linear accelerators as drivers for free electron lasers (FEL) and the advent of single-pass (SASE) FELs has driven the development of a wide range of diagnostic techniques for measuring the length and longitudinal distribution of short and ultra-short electron bunches. For SASE FELs the radiation power and the length of the undulator needed to achieve saturation depend strongly on the charge density of the electron beam. In the case of X-ray FELs, this requires the accelerator to produce ultra-high brightness beams with micron size transverse normalized emittances and peak currents of several kA through several stages of magnetic bunch compression. Different longitudinal diagnostics are employed to measure the peak current and bunch profile along these stages. The measurement techniques can be distinguished into different classes. Coherent methods detect the light emitted from the beam by some coherent radiation process (spectroscopic measurement), or directly measure the Coulomb field traveling with the beam (electro-optic). Phase space manipulation techniques map the time coordinate onto a transverse dimension and then use conventional transverse beam diagnostics (transverse deflector, rf zero-phasing). Further methods measure the profile or duration of an incoherent light pulse emitted by the bunch at wavelengths much shorted than the bunch length (streak camera, fluctuation technique) or modulate the electron beam at an optical wavelength and then generate a narrow bandwidth radiation pulse with the longitudinal profile of

  6. Inclusive charge longitudinal response in finite nuclei

    International Nuclear Information System (INIS)

    Alberico, W.M.; Molinari, A.; Czerski, P.; Czerski, P.; Ericson, M.

    1986-03-01

    The experimental dynamic and static longitudinal structure factors of 12 C, 40 Ca and 56 Fe are investigated with a semiclassical RPA theory. The parameters entering into the nuclear mean field (including the nucleon effective mass) and in the isoscalar and isovector particle-hole forces are set by best fitting procedures. Quite reasonable values of these quantities allow a satisfactory account of the experimental data over a wide range of momentum transfers in all the three nuclei. However, to achieve this result, the proton root mean square radius has to be increased over the conventional value of about 13% in 12 C and 22% in 40 Ca and 56 Fe

  7. Longitudinal vortices in a transitioning boundary layer

    International Nuclear Information System (INIS)

    Anders, J.B.; Backwelder, R.F.

    1980-01-01

    Naturally occurring spanwise variations of the streamwise velocity component, characteristic of longitudinal vortices embedded in a transitioning boundary layer were explored using hot-wire anemometers. A vibrating ribbon introduced stable or unstable Tollmien-Schlichting waves into the laminar boundary layer. These damped or growing disturbances always developed a strong three-dimensional pattern even though no spanwise perturbations were artificially induced. Changing the radius of the leading edge and other modifications to the flat plate, wind tunnel and boundary layer did not alter the spanwise wavelength of the vortices. (orig.)

  8. Longitudinal dynamics of laser-cooled fast ion beams

    DEFF Research Database (Denmark)

    Weidemüller, M.; Eike, B.; Eisenbarth, U.

    1999-01-01

    We present recent results of our experiments on laser cooling of fast stored ion beams at the Heidelberg Test Storage Ring. The longitudinal motion of the ions is directly cooled by the light pressure force, whereas efficient transverse cooling is obtained indirectly by longitudinal-transverse co......We present recent results of our experiments on laser cooling of fast stored ion beams at the Heidelberg Test Storage Ring. The longitudinal motion of the ions is directly cooled by the light pressure force, whereas efficient transverse cooling is obtained indirectly by longitudinal....... When applying laser cooling in square-well buckets over long time intervals, hard Coulomb collisions suddenly disappear and the longitudinal temperature drops by about a factor of three. The observed longitudinal behaviour of the beam shows strong resemblance with the transition to an Coulomb...

  9. Longitudinal Muscle Dysfunction in Achalasia Esophagus and Its Relevance

    OpenAIRE

    Mittal, Ravinder K; Hong, Su Jin; Bhargava, Valmik

    2013-01-01

    Muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. Goal of this review is to summarize the role of longitudinal muscle in physiology and pathophysiology of esophageal sensory and motor function. Simultaneous manometry and ultrasound imaging that measure circular and longitudinal muscle contraction respectively reveal that during peristalsis 2 layers of the esophagus contract in perfect synchrony. On the other hand, during transient relaxation of the...

  10. Longitudinal data analysis a handbook of modern statistical methods

    CERN Document Server

    Fitzmaurice, Garrett; Verbeke, Geert; Molenberghs, Geert

    2008-01-01

    Although many books currently available describe statistical models and methods for analyzing longitudinal data, they do not highlight connections between various research threads in the statistical literature. Responding to this void, Longitudinal Data Analysis provides a clear, comprehensive, and unified overview of state-of-the-art theory and applications. It also focuses on the assorted challenges that arise in analyzing longitudinal data. After discussing historical aspects, leading researchers explore four broad themes: parametric modeling, nonparametric and semiparametric methods, joint

  11. Longitudinal Phase Space Tomography with Space Charge

    CERN Document Server

    Hancock, S; Lindroos, M

    2000-01-01

    Tomography is now a very broad topic with a wealth of algorithms for the reconstruction of both qualitative and quantitative images. In an extension in the domain of particle accelerators, one of the simplest algorithms has been modified to take into account the non-linearity of large-amplitude synchrotron motion. This permits the accurate reconstruction of longitudinal phase space density from one-dimensional bunch profile data. The method is a hybrid one which incorporates particle tracking. Hitherto, a very simple tracking algorithm has been employed because only a brief span of measured profile data is required to build a snapshot of phase space. This is one of the strengths of the method, as tracking for relatively few turns relaxes the precision to which input machine parameters need to be known. The recent addition of longitudinal space charge considerations as an optional refinement of the code is described. Simplicity suggested an approach based on the derivative of bunch shape with the properties of...

  12. Tomographic Measurements of Longitudinal Phase Space Density

    CERN Document Server

    Hancock, S; McIntosh, E; Metcalf, M

    1999-01-01

    Tomography : the reconstruction of a two-dimensional image from a series of its one-dimensional projections is now a very broad topic with a wealth of algorithms for the reconstruction of both qualitative and quantitative images. One of the simplest algorithms has been modified to take into account the non-linearity of large-amplitude synchrotron motion in a particle accelerator. This permits the accurate reconstruction of longitudinal phase space density from one-dimensional bunch profile data. The algorithm was developed in Mathematica TM in order to exploit the extensive built-in functions and graphics. Subsequently, it has been recoded in Fortran 90 with the aim of reducing the execution time by at least a factor of one hundred. The choice of Fortran 90 was governed by the desire ultimately to exploit parallel architectures, but sequential compilation and execution have already largely yielded the required gain in speed. The use of the method to produce longitudinal phase space plots, animated sequences o...

  13. A longitudinal study of urea cycle disorders.

    Science.gov (United States)

    Batshaw, Mark L; Tuchman, Mendel; Summar, Marshall; Seminara, Jennifer

    2014-01-01

    The Urea Cycle Disorders Consortium (UCDC) is a member of the NIH funded Rare Diseases Clinical Research Network and is performing a longitudinal study of 8 urea cycle disorders (UCDs) with initial enrollment beginning in 2006. The consortium consists of 14 sites in the U.S., Canada and Europe. This report summarizes data mining studies of 614 patients with UCDs enrolled in the UCDC's longitudinal study protocol. The most common disorder is ornithine transcarbamylase deficiency, accounting for more than half of the participants. We calculated the overall prevalence of urea cycle disorders to be 1/35,000, with 2/3rds presenting initial symptoms after the newborn period. We found the mortality rate to be 24% in neonatal onset cases and 11% in late onset cases. The most common precipitant of clinical hyperammonemic episodes in the post-neonatal period was intercurrent infections. Elevations in both blood ammonia and glutamine appeared to be biomarkers for neurocognitive outcome. In terms of chronic treatment, low protein diet appeared to result in normal weight but decreased linear growth while N-scavenger therapy with phenylbutyrate resulted in low levels of branched chain amino acids. Finally, we found an unexpectedly high risk for hepatic dysfunction in patients with ornithine transcarbamylase deficiency. This natural history study illustrates how a collaborative study of a rare genetic disorder can result in an improved understanding of morbidity and disease outcome. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Parental mediation and cyberbullying - a longitudinal study.

    Science.gov (United States)

    Chng, Grace S; Liau, Albert; Khoo, Angeline; Li, Dongdong

    2014-01-01

    Parents use active and restrictive mediation strategies to guide and regulate children's online participation and the online risks they encounter. However, changes in parental mediation do occur over time and the effectiveness of these strategies on cyberbullying demands for further empirical investigation. The current study addresses these issues with a sample of 1084 students (49% girls) in a longitudinal, three-wave design. Gender differences were tested via multi-group analyses. Longitudinal growth models showed that parental use of both active and restrictive mediation decreased over time. For both types of mediation, the mean rate of change had a significant effect on boys' engagement in cyberbullying, but not for girls. Initial levels of restrictive mediation, but not active mediation, were found to be significantly predictive of cyberbullying in both genders. Girls had higher initial levels of both parental mediation types in comparison to boys. The results reveal that the effectiveness of active and restrictive mediation in relation to students' cyberbullying differs and informs us on gender differences. The implications of these results for parental education in online mediation are discussed.

  15. Longitudinal density monitor for the LHC

    Science.gov (United States)

    Jeff, A.; Andersen, M.; Boccardi, A.; Bozyigit, S.; Bravin, E.; Lefevre, T.; Rabiller, A.; Roncarolo, F.; Welsch, C. P.; Fisher, A. S.

    2012-03-01

    The longitudinal density monitor (LDM) is primarily intended for the measurement of the particle population in nominally empty rf buckets. These so-called satellite or ghost bunches can cause problems for machine protection as well as influencing the luminosity calibration of the LHC. The high dynamic range of the system allows measurement of ghost bunches with as little as 0.01% of the main bunch population at the same time as characterization of the main bunches. The LDM is a single-photon counting system using visible synchrotron light. The photon detector is a silicon avalanche photodiode operated in Geiger mode, which allows the longitudinal distribution of the LHC beams to be measured with a resolution of 90 ps. Results from the LDM are presented, including a proposed method for constructing a 3-dimensional beam density map by scanning the LDM sensor in the transverse plane. In addition, we present a scheme to improve the sensitivity of the system by using an optical switching technique.

  16. Longitudinal density monitor for the LHC

    Directory of Open Access Journals (Sweden)

    A. Jeff

    2012-03-01

    Full Text Available The longitudinal density monitor (LDM is primarily intended for the measurement of the particle population in nominally empty rf buckets. These so-called satellite or ghost bunches can cause problems for machine protection as well as influencing the luminosity calibration of the LHC. The high dynamic range of the system allows measurement of ghost bunches with as little as 0.01% of the main bunch population at the same time as characterization of the main bunches. The LDM is a single-photon counting system using visible synchrotron light. The photon detector is a silicon avalanche photodiode operated in Geiger mode, which allows the longitudinal distribution of the LHC beams to be measured with a resolution of 90 ps. Results from the LDM are presented, including a proposed method for constructing a 3-dimensional beam density map by scanning the LDM sensor in the transverse plane. In addition, we present a scheme to improve the sensitivity of the system by using an optical switching technique.

  17. Longitudinal emission tomography of thyroid and heart

    International Nuclear Information System (INIS)

    Giessen, J.W. van.

    1986-01-01

    In this thesis three devices are discussed for longitudinal emission tomography, one of which has been developed for myocardial imaging and the other two for thyroid imaging. Longitudinal emission tomography is a technique which enables three-dimensional reconstruction of the radioactivity distribution within an organ from two-dimensional distributions on a detector surface. In Ch. 1 a general survey is given of the clinical environment in which the devices will be used. Ch. 2 discusses a well-known technique for myocardial imaging: seven-pinhole tomography. In Ch. 3 this technique is applied to imaging of the thyroid. Three different reconstruction methods have been applied to the data collected with the system (from phantoms as well as from patients) and the results have been evaluated. Ch. 4 discusses simulation studies which were carried out in order to investigate the potentialities of a time-coded aperture (TCA) system designed for thyroid tomography. In Ch. 5 a prototype is tested of the time coded aperture in a clinical environment. The last chapter presents a comparison between the (thyroid) 7P collimator and the TCA device. (Auth.)

  18. Splinting of Longitudinal Fracture: An Innovative Approach

    Directory of Open Access Journals (Sweden)

    Rashmi Bansal

    2016-01-01

    Full Text Available Trauma may result in craze lines on the enamel surface, one or more fractured cusps of posterior teeth, cracked tooth syndrome, splitting of posterior teeth, and vertical fracture of root. Out of these, management of some fractures is of great challenge and such teeth are generally recommended for extraction. Literature search reveals attempts to manage such fractures by full cast crown, orthodontic wires, and so forth, in which consideration was given to extracoronal splinting only. However, due to advancement in materials and technologies, intracoronal splinting can be achieved as well. In this case report, longitudinal fractures in tooth #27, tooth #37, and tooth #46 had occurred. In #27, fracture line was running mesiodistally involving the pulpal floor resulting in a split tooth. In teeth 37 and 46, fractures of the mesiobuccal cusp and mesiolingual cusp were observed, respectively. They were restored with cast gold inlay and full cast crown, respectively. Longitudinal fracture of 27 was treated with an innovative approach using intracanal reinforced composite with Ribbond, external reinforcement with an orthodontic band, and full cast metal crown to splint the split tooth.

  19. Posterior longitudinal ligament status in cervical spine bilateral facet dislocations

    International Nuclear Information System (INIS)

    Carrino, John A.; Manton, Geoffrey L.; Morrison, William B.; Flanders, Adam E.; Vaccaro, Alex R.; Schweitzer, Mark E.

    2006-01-01

    It is generally accepted that cervical spine bilateral facet dislocation results in complete disruption of the posterior longitudinal ligament. The goal of this study was to evaluate the integrity of numerous spine-stabilizing structures by MRI, and to determine if any associations between injury patterns exist with respect to the posterior longitudinal ligament status. Retrospective case series. A retrospective review was performed of 30 cervical spine injury subjects with bilateral facet dislocation. Assessment of 1.5T MRI images was carried out for: intervertebral disc disruption, facet fracture, and ligamentous disruption. Statistical analyses were performed to evaluate for associations between various injury patterns and posterior longitudinal ligament status. The frequency of MRI abnormalities was: anterior longitudinal ligament disruption (26.7%), disc herniation or disruption (90%), posterior longitudinal ligament disruption (40%), facet fracture (63.3%) and disruption of the posterior column ligament complex (97%). There were no significant associations between injury to the posterior longitudinal ligament and other structures. Compared to surgical reports, MRI was accurate for determining the status for 24 of 26 ligaments (three of three anterior longitudinal ligament, seven of nine posterior longitudinal ligament, and 14 of 14 posterior column ligament complex) but generated false negatives in two instances (in both MRI showed an intact posterior longitudinal ligament that was torn at surgery). (orig.)

  20. Longitudinal muscle dysfunction in achalasia esophagus and its relevance.

    Science.gov (United States)

    Mittal, Ravinder K; Hong, Su Jin; Bhargava, Valmik

    2013-04-01

    Muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. Goal of this review is to summarize the role of longitudinal muscle in physiology and pathophysiology of esophageal sensory and motor function. Simultaneous manometry and ultrasound imaging that measure circular and longitudinal muscle contraction respectively reveal that during peristalsis 2 layers of the esophagus contract in perfect synchrony. On the other hand, during transient relaxation of the lower esophageal sphincter (LES), longitudinal muscle contracts independently of circular muscle. Recent studies provide novel insights, i.e., longitudinal muscle contraction of the esophagus induces LES relaxation and possibly descending relaxation of the esophagus. In achalasia esophagus and other motility disorders there is discoordination between the 2 muscle layers. Longitudinal muscle contraction patterns are different in the recently described three types of achalasia identified by high-resolution manometry. Robust contraction of the longitudinal muscle in type II achalasia causes pan-esophageal pressurization and is the mechanism of whatever little esophageal emptying that take place in the absence of peristalsis and impaired LES relaxation. It may be that preserved longitudinal muscle contraction is also the reason for superior outcome to medical/surgical therapy in type II achalasia esophagus. Prolonged contractions of longitudinal muscles of the esophagus is a possible mechanism of heartburn and "angina like" pain seen in esophageal motility disorders and possibly achalasia esophagus. Novel techniques to record longitudinal muscle contraction are on the horizon. Neuro-pharmacologic control of circular and longitudinal muscles is different, which provides an important opportunity for the development of novel pharmacological therapies to treat sensory and motor disorders of the esophagus.

  1. Longitudinal collective echoes in coasting particle beams

    Directory of Open Access Journals (Sweden)

    Ahmed Al-Khateeb

    2003-01-01

    Full Text Available Longitudinal ballistic and collective beam echoes with diffusion effects are investigated theoretically. In the presence of the space-charge impedance, the collective echo amplitude is obtained as a closed form expression. In contrast to the ballistic case, the collective echo amplitude consists of one maximum at time t_{echo}. The echo amplitude grows up and damps down with a rate proportional to the Landau damping rate of space-charge waves. The effect of weak diffusion is found to modify the ballistic and the collective echo amplitudes in the same manner. This effect of diffusion was confirmed using a “noiseless,” grid-based simulation code. As a first application the amount of numerical diffusion in our simulation code was determined using the echo effect.

  2. Granger Causality Testing with Intensive Longitudinal Data.

    Science.gov (United States)

    Molenaar, Peter C M

    2018-06-01

    The availability of intensive longitudinal data obtained by means of ambulatory assessment opens up new prospects for prevention research in that it allows the derivation of subject-specific dynamic networks of interacting variables by means of vector autoregressive (VAR) modeling. The dynamic networks thus obtained can be subjected to Granger causality testing in order to identify causal relations among the observed time-dependent variables. VARs have two equivalent representations: standard and structural. Results obtained with Granger causality testing depend upon which representation is chosen, yet no criteria exist on which this important choice can be based. A new equivalent representation is introduced called hybrid VARs with which the best representation can be chosen in a data-driven way. Partial directed coherence, a frequency-domain statistic for Granger causality testing, is shown to perform optimally when based on hybrid VARs. An application to real data is provided.

  3. Longitudinal wake field corrections in circular machines

    International Nuclear Information System (INIS)

    Symon, K.R.

    1996-01-01

    In computations of longitudinal particle motions in accelerators and storage rings, the fields produced by the interactions of the beam with the cavity in which it circulates are usually calculated by multiplying Fourier components of the beam current by the appropriate impedances. This procedure neglects the slow variation with time of the Fourier coefficients and of the beam revolution frequency. When there are cavity elements with decay times that are comparable with or larger than the time during which changes in the beam parameters occur, these changes can not be neglected. Corrections for this effect have been worked out in terms of the response functions of elements in the ring. The result is expressed as a correction to the impedance which depends on the way in which the beam parameters are changing. A method is presented for correcting a numerical simulation by keeping track of the steady state and transient terms in the response of a cavity

  4. Longitudinal magnetic bistability of electroplated wires

    International Nuclear Information System (INIS)

    Kurlyandskaya, G.V.; Garcia-Miquel, H.; Vazquez, M.; Svalov, A.V.; Vas'kovskiy, V.O.

    2002-01-01

    Fe 20 Ni 74 Co 6 and Fe 20 Ni 64 Co 16 1 μm thick magnetic tubes electroplated onto Cu 98 Be 2 conductive wire have been investigated in as-deposited state, after heat treatment under longitudinal magnetic field for 1 h at 330 deg. C, and after rf-sputtering deposition of the additional 2 μm Fe 19 Ni 81 layer. Heat treatments and an additional layer deposition modify the shape of hysteresis loops. Magnetically bistable behaviour, observed after the field annealing at a temperature of 330 deg. C, is studied as a function of the length of the samples. This is the first report by our knowledge on the bistable behaviour of the electroplated wires. The bistability of these wires is promising for applications such as tagging or pulse generator applications

  5. A Longitudinal Study of Prisoners on Remand

    DEFF Research Database (Denmark)

    Andersen, Henrik Steen; Sestoft, Dorte; Lillebæk, Tommy

    2000-01-01

    Objective: To compare two levels of stress (solitary confinement (SC) and non-SC) among remand prisoners as to incidence of psychiatric disorders in relation to prevalent disorders. Method: Longitudinal repeated assessments were carried out from the start and during the remand phase of imprisonment....... Both interview-based and self-reported measures were applied to 133 remand prisoners in SC and 95 remand prisoners in non-SC randomly selected in a parallel study design. Results: Incidence of psychiatric disorders developed in the prison was significantly higher in SC prisoners (28%) than in non......-SC prisoners (15%). Most disorders were adjustment disorders, with depressive disorders coming next. Incident psychotic disorders were rare. The difference regarding incidence was primarily explained by level of stress (i.e. prison form) rather than confounding factors. Quantitative measures of psychopathology...

  6. Beam measurements of the SPS longitudinal impedance

    CERN Document Server

    Lasheen, A

    2017-01-01

    Longitudinal instabilities are one of the main limitationsin the CERN SPS to reach the beam parameters requiredfor the High Luminosity LHC project. In preparation tothe SPS upgrade, possible remedies are studied by perform-ing macroparticle simulations using the machine impedancemodel obtained from electromagnetic simulations and mea-surements. To benchmark the impedance model, the resultsof simulations are compared with various beam measure-ments. In this study, the reactive part of the impedance wasprobed by measuring the quadrupole frequency shift withintensity, obtained from bunch length oscillations at mis-matched injection into the SPS. This method was appliedover many last years to follow up the evolution of the SPSimpedance, injecting bunches with the same bunch length.A novel approach, giving significantly more information,consists in varying the injected bunch length. The compari-son of these measurements with macroparticle simulationsallowed to test the existing model and identify some missingSPS i...

  7. Linear mixed models for longitudinal data

    CERN Document Server

    Molenberghs, Geert

    2000-01-01

    This paperback edition is a reprint of the 2000 edition. This book provides a comprehensive treatment of linear mixed models for continuous longitudinal data. Next to model formulation, this edition puts major emphasis on exploratory data analysis for all aspects of the model, such as the marginal model, subject-specific profiles, and residual covariance structure. Further, model diagnostics and missing data receive extensive treatment. Sensitivity analysis for incomplete data is given a prominent place. Several variations to the conventional linear mixed model are discussed (a heterogeity model, conditional linear mixed models). This book will be of interest to applied statisticians and biomedical researchers in industry, public health organizations, contract research organizations, and academia. The book is explanatory rather than mathematically rigorous. Most analyses were done with the MIXED procedure of the SAS software package, and many of its features are clearly elucidated. However, some other commerc...

  8. A typology of longitudinal integrated clerkships.

    Science.gov (United States)

    Worley, Paul; Couper, Ian; Strasser, Roger; Graves, Lisa; Cummings, Beth-Ann; Woodman, Richard; Stagg, Pamela; Hirsh, David

    2016-09-01

    Longitudinal integrated clerkships (LICs) represent a model of the structural redesign of clinical education that is growing in the USA, Canada, Australia and South Africa. By contrast with time-limited traditional block rotations, medical students in LICs provide comprehensive care of patients and populations in continuing learning relationships over time and across disciplines and venues. The evidence base for LICs reveals transformational professional and workforce outcomes derived from a number of small institution-specific studies. This study is the first from an international collaborative formed to study the processes and outcomes of LICs across multiple institutions in different countries. It aims to establish a baseline reference typology to inform further research in this field. Data on all LIC and LIC-like programmes known to the members of the international Consortium of Longitudinal Integrated Clerkships were collected using a survey tool developed through a Delphi process and subsequently analysed. Data were collected from 54 programmes, 44 medical schools, seven countries and over 15 000 student-years of LIC-like curricula. Wide variation in programme length, student numbers, health care settings and principal supervision was found. Three distinct typological programme clusters were identified and named according to programme length and discipline coverage: Comprehensive LICs; Blended LICs, and LIC-like Amalgamative Clerkships. Two major approaches emerged in terms of the sizes of communities and types of clinical supervision. These referred to programmes based in smaller communities with mainly family physicians or general practitioners as clinical supervisors, and those in more urban settings in which subspecialists were more prevalent. Three distinct LIC clusters are classified. These provide a foundational reference point for future studies on the processes and outcomes of LICs. The study also exemplifies a collaborative approach to medical

  9. Longitudinal expansion of field line dipolarization

    Science.gov (United States)

    Saka, O.; Hayashi, K.

    2017-11-01

    We examine the substorm expansions that started at 1155 UT 10 August 1994 in the midnight sector focusing on the longitudinal (eastward) expansion of field line dipolarization in the auroral zone. Eastward expansion of the dipolarization region was observed in all of the H, D, and Z components. The dipolarization that started at 1155 UT (0027 MLT) from 260° of geomagnetic longitude (CMO) expanded to 351°(PBQ) in about 48 min. The expansion velocity was 0.03-0.04°/s, or 1.9 km/s at 62°N of geomagnetic latitude. The dipolarization region expanding to the east was accompanied by a bipolar event at the leading edge of the expansion in latitudes equatorward of the westward electrojet (WEJ). In the midnight sector at the onset meridian, the Magnetospheric Plasma Analyzer (MAP) on board geosynchronous satellite L9 measured electrons and ions between 10 eV and 40 keV. We conclude from the satellite observations that this dipolarization was characterized by the evolution of temperature anisotropies, an increase of the electron and ion temperatures, and a rapid change in the symmetry axis of the temperature tensor. The field line dipolarization and its longitudinal expansion were interpreted in terms of the slow MHD mode triggered by the current disruption. We propose a new magnetosphere-ionosphere coupling (MI-coupling) mechanism based on the scenario that transmitted westward electric fields from the magnetosphere in association with expanding dipolarization produced electrostatic potential (negative) in the ionosphere through differences in the mobility of collisional ions and collisionless electrons. The field-aligned currents that emerged from the negative potential region are arranged in a concentric pattern around the negative potential region, upward toward the center and downward on the peripheral.

  10. Antisocial Behavior and Depressive Symptoms: Longitudinal and Concurrent Relations

    Science.gov (United States)

    Vieno, Alessio; Kiesner, Jeff; Pastore, Massimiliano; Santinello, Massimo

    2008-01-01

    The relations between antisocial behavior and depressive symptoms were examined both longitudinally and concurrently in a sample of Italian early-adolescents. Structural equation modelling was applied to 10-month longitudinal data from a sample of 107 youths (54 girls; mean age at baseline = M = 12.5). Early adolescents completed a questionnaire…

  11. Future Orientation, Impulsivity, and Problem Behaviors: A Longitudinal Moderation Model

    Science.gov (United States)

    Chen, Pan; Vazsonyi, Alexander T.

    2011-01-01

    In the current study, based on a sample of 1,873 adolescents between 11.4 and 20.9 years of age from the first 3 waves of the National Longitudinal Study of Adolescent Health, we investigated the longitudinal effects of future orientation on levels of and developmental changes in problem behaviors, while controlling for the effects by impulsivity;…

  12. Physics and technology of tunable pulsed single longitudinal mode ...

    Indian Academy of Sciences (India)

    precious materials. In particular, single-longitudinal mode dye lasers are useful ... to the longitudinal mode spacing of 10 GHz. Grating of 3300 .... the band of wavelength covering 3 pm and SLM operation was shown in the band of 0.5 pm.

  13. 14 CFR 23.173 - Static longitudinal stability.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Static longitudinal stability. 23.173... Stability § 23.173 Static longitudinal stability. Under the conditions specified in § 23.175 and with the airplane trimmed as indicated, the characteristics of the elevator control forces and the friction within...

  14. A Longitudinal Study of Adolescent Adjustment Following Family Transitions

    Science.gov (United States)

    Ruschena, Eda; Prior, Margot; Sanson, Ann; Smart, Diana

    2005-01-01

    Background: This study examined the impact of family transitions, that is, parental separation, divorce, remarriage and death, upon the lives of Australian children and adolescents in a longitudinal study of temperament and development. Methods: Using longitudinal and concurrent questionnaire data, outcomes for young people experiencing…

  15. Learning from Longitudinal Research in Criminology and the Health Sciences

    Science.gov (United States)

    Vanderstaay, Steven L.

    2006-01-01

    This article reviews longitudinal research within criminology and the health sciences on the relationship between reading and criminal, delinquent, or antisocial behavior. Longitudinal research in criminology, medicine, and psychology examines the role of reading within a broad set of interactive processes, connecting literacy to public health via…

  16. Longitudinal and transverse polarizations in the deep inelastic reactions

    International Nuclear Information System (INIS)

    Bressan, A.

    1996-07-01

    This course is an introduction to the dominant effects of longitudinal and transverse spin in deep inelastic reactions. Only the effects present to the 'leading twist' are attacked. The mass and transverse impulsion of partons are neglected. We will attach to bring out the respective specificities of longitudinal and transverse polarizations. (N.C.)

  17. Longitudinal Trajectories of Perceived Body Weight: Adolescence to Early Adulthood

    Science.gov (United States)

    Seo, Dong-Chul; Li, Kaigang

    2012-01-01

    Objective: To examine longitudinal trajectories of perceived weight from adolescence to early adulthood by gender. Methods: We analyzed 9 waves (1997-2005) of data from the National Longitudinal Survey of Youth (N = 8302) using Mplus. Results: Perceived overweight increased over time among girls and did not level off until 23 years of age. Blacks…

  18. Simulation of the longitudinal instabilities of the asymmetric bunches

    International Nuclear Information System (INIS)

    Dai Jianping; Zhao Zhentang

    2002-01-01

    The computational model of the code used to simulate the longitudinal instabilities of the asymmetric bunches was introduced. The growth rates of the longitudinal instabilities of the symmetric bunches got by this code were compared with those got by the code ZAP, and they were almost the same. As an example, the simulation results of the BEPC-II were presented

  19. Requirements for longitudinal HOM damping in superconducting recirculating linacs

    International Nuclear Information System (INIS)

    Bisognano, J.J.; Fripp, M.L.

    1989-01-01

    Transverse beam breakup provides the primary current limitation in the operation of superconducting recirculating linacs and requires the significant damping of transverse-deflecting higher order modes. The need to damp the coexisting longitudinal HOMs in these nominally isochronous machines, however, is not as clear. Isochronicity implies that energy variations induced by excitation of longitudinal modes do not translate directly into position and current modulations. Such modulations, if present, could enhance the initial excitation, effectively closing a potentially unstable feedback loop. Design optimization of cavity structures may suggest that no longitudinal damping be provided. On the other hand, easing of the isochronicity requirement may provide desired flexibility in lattice design. In this note, limits are placed on the requirements for longitudinal HOM damping and on the tolerances for isochronicity which are driven by possible longitudinal multipass phenomena. 2 refs., 1 fig

  20. Longitudinal Control for Mengshi Autonomous Vehicle via Gauss Cloud Model

    Directory of Open Access Journals (Sweden)

    Hongbo Gao

    2017-12-01

    Full Text Available Dynamic robustness and stability control is a requirement for self-driving of autonomous vehicle. Longitudinal control technique of autonomous vehicle is basic theory and one key complex technique which must have the reliability and precision of vehicle controller. The longitudinal control technique is one of the foundations of the safety and stability of autonomous vehicle control. In our paper, we present a longitudinal control algorithm based on cloud model for Mengshi autonomous vehicle to ensure the dynamic stability and tracking performance of Mengshi autonomous vehicle. The longitudinal control algorithm mainly uses cloud model generator to control the acceleration of the autonomous vehicle to achieve the goal that controls the speed of Mengshi autonomous vehicle. The proposed longitudinal control algorithm based on cloud model is verified by real experiments on Highway driving scene. The experiments results of the acceleration and speed show that the algorithm is validity and stability.

  1. Sequential Progressions in a Theory of Mind Scale: Longitudinal Perspectives

    Science.gov (United States)

    Wellman, Henry M.; Fuxi, Fang; Peterson, Candida C.

    2011-01-01

    Consecutive re-testings of 92 U.S. preschoolers (n = 30), Chinese preschoolers (n = 31), and deaf children (n = 31) examined whether the sequences of development apparent in cross-sectional results with a theory-of-mind scale also appeared in longitudinal assessment. Longitudinal data confirmed that theory-of-mind progressions apparent in cross-sectional scaling data also characterized longitudinal sequences of understanding for individual children. The match between cross-sectional and longitudinal sequences appeared for children who exhibit different progressions across cultures (U.S. vs. China) and for children with substantial delays (deaf children of hearing parents). Moreover, greater scale distances reflected larger longitudinal age differences. PMID:21428982

  2. Cross-Sectional Analysis of Longitudinal Mediation Processes.

    Science.gov (United States)

    O'Laughlin, Kristine D; Martin, Monica J; Ferrer, Emilio

    2018-01-01

    Statistical mediation analysis can help to identify and explain the mechanisms behind psychological processes. Examining a set of variables for mediation effects is a ubiquitous process in the social sciences literature; however, despite evidence suggesting that cross-sectional data can misrepresent the mediation of longitudinal processes, cross-sectional analyses continue to be used in this manner. Alternative longitudinal mediation models, including those rooted in a structural equation modeling framework (cross-lagged panel, latent growth curve, and latent difference score models) are currently available and may provide a better representation of mediation processes for longitudinal data. The purpose of this paper is twofold: first, we provide a comparison of cross-sectional and longitudinal mediation models; second, we advocate using models to evaluate mediation effects that capture the temporal sequence of the process under study. Two separate empirical examples are presented to illustrate differences in the conclusions drawn from cross-sectional and longitudinal mediation analyses. Findings from these examples yielded substantial differences in interpretations between the cross-sectional and longitudinal mediation models considered here. Based on these observations, researchers should use caution when attempting to use cross-sectional data in place of longitudinal data for mediation analyses.

  3. The Role of Microsimulation in Longitudinal Data Analysis

    Directory of Open Access Journals (Sweden)

    Douglas A. Wolf

    2001-12-01

    microsimulation also has the potential to contribute to longitudinal data analysis in several ways, including extending the range of outputs generated by a model, addressing several defective-data problems, and serving as a vehicle for missing-data imputation. This paper discusses microsimulation procedures suitable for several commonly-used statistical models applied to longitudinal data. It also addresses the unique role that can be played by microsimulation in longitudinal data analysis, and the problem of accounting for the several sources of variability associated with microsimulation procedures.

  4. A single hole tracer test to determine longitudinal dispersion

    International Nuclear Information System (INIS)

    Noy, D.J.; Holmes, D.C.

    1986-03-01

    The paper concerns a single hole tracer test to determine longitudinal dispersion, which is an important parameter in assessing the suitability of a site for radioactive waste disposal. The theory, equipment and procedure for measuring longitudinal dispersion in a single borehole is described. Results are presented for field trials conducted in an aquifer, where the technique produced good results. The measured value of longitudinal dispersion, from a single hole test, relates only to a limited volume of rock immediately adjacent to the borehole. (U.K.)

  5. A Semiparametric Marginalized Model for Longitudinal Data with Informative Dropout

    Directory of Open Access Journals (Sweden)

    Mengling Liu

    2012-01-01

    Full Text Available We propose a marginalized joint-modeling approach for marginal inference on the association between longitudinal responses and covariates when longitudinal measurements are subject to informative dropouts. The proposed model is motivated by the idea of linking longitudinal responses and dropout times by latent variables while focusing on marginal inferences. We develop a simple inference procedure based on a series of estimating equations, and the resulting estimators are consistent and asymptotically normal with a sandwich-type covariance matrix ready to be estimated by the usual plug-in rule. The performance of our approach is evaluated through simulations and illustrated with a renal disease data application.

  6. Longitudinal Electron Bunch Diagnostics Using Coherent Transition Radiation

    CERN Document Server

    Mihalcea, Daniel; Happek, Uwe; Regis-Guy Piot, Philippe

    2005-01-01

    The longitudinal charge distribution of electron bunches in the Fermilab A0 photo-injector was determined by using the coherent transition radiation produced by electrons passing through a thin metallic foil. The auto-correlation of the transition radiation signal was measured with a Michelson type interferometer. The response function of the interferometer was determined from measured and simulated power spectra for low electron bunch charge and maximum longitudinal compression. Kramers-Kroning technique was used to determine longitudinal charge distribution. Measurements were performed for electron bunch lengths in the range from 0.3 to 2 ps (rms).

  7. Signal processing for longitudinal parameters of the Tevatron beam

    International Nuclear Information System (INIS)

    Pordes, S.; Crisp, J.; Fellenz, B.; Flora, R.; Para, A.; Tollestrup, A.V.

    2005-01-01

    We describe the system known as the Tevatron SBD [1] which is used to provide information on the longitudinal parameters of coalesced beam bunches in the Tevatron. The system has been upgraded over the past year with a new digitizer and improved software. The quantities provided for each proton and antiproton bunch include the intensity, the longitudinal bunch profile, the timing of the bunch with respect to the low-level RF, the momentum spread and the longitudinal emittance. The system is capable of 2 Hz operation and is run at 1 Hz

  8. The Fundamentals of Longitudinal Research: An Overview

    Directory of Open Access Journals (Sweden)

    Rajulton, Fernando

    2001-01-01

    Full Text Available EnglishThis paper outlines briefly the historical development of ideas related tolongitudinal studies and their advantages over cross-sectional studies. Then it points out a fewcomplicating factors that arise with the analysis of longitudinal data and highlights some of theapproaches adopted to manage those complicating factors and illustrated in the papers included in thisSpecial Issue. The overall aim is to promote a better understanding of the information thatlongitudinal data provide and of the suitable techniques needed to analyze such data.FrenchCet article trace brièvement le développement historique des idées liées àl’avantage des études longitudinales par rapport aux études transversales. Je préciseensuite quelques facteurs qui compliquent les analyses des données longitudinaleset je met en valeur certaines des approches adoptées pour contrôler ces facteurs etj’illustre par des exemples tirés de cette édition spéciale. Le but général estd’atteindre une meilleure compréhension de l'information que les donnéeslongitudinales fournissent et des techniques appropriées requises pour analyser detelles données.

  9. Regression analysis of sparse asynchronous longitudinal data.

    Science.gov (United States)

    Cao, Hongyuan; Zeng, Donglin; Fine, Jason P

    2015-09-01

    We consider estimation of regression models for sparse asynchronous longitudinal observations, where time-dependent responses and covariates are observed intermittently within subjects. Unlike with synchronous data, where the response and covariates are observed at the same time point, with asynchronous data, the observation times are mismatched. Simple kernel-weighted estimating equations are proposed for generalized linear models with either time invariant or time-dependent coefficients under smoothness assumptions for the covariate processes which are similar to those for synchronous data. For models with either time invariant or time-dependent coefficients, the estimators are consistent and asymptotically normal but converge at slower rates than those achieved with synchronous data. Simulation studies evidence that the methods perform well with realistic sample sizes and may be superior to a naive application of methods for synchronous data based on an ad hoc last value carried forward approach. The practical utility of the methods is illustrated on data from a study on human immunodeficiency virus.

  10. Analysis of critically refracted longitudinal waves

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Ning, E-mail: npei@iastate.edu; Bond, Leonard J., E-mail: npei@iastate.edu [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)

    2015-03-31

    Fabrication processes, such as, welding, forging, and rolling can induce residual stresses in metals that will impact product performance and phenomena such as cracking and corrosion. To better manage residual stress tools are needed to map their distribution. The critically refracted ultrasonic longitudinal (LCR) wave is one such approach that has been used for residual stress characterization. It has been shown to be sensitive to stress and less sensitive to the effects of the texture of the material. Although the LCR wave is increasingly widely applied, the factors that influence the formation of the LCR beam are seldom discussed. This paper reports a numerical model used to investigate the transducers' parameters that can contribute to the directionality of the LCR wave and hence enable performance optimization when used for industrial applications. An orthogonal test method is used to study the transducer parameters which influence the LCR wave beams. This method provides a design tool that can be used to study and optimize multiple parameter experiments and it can identify which parameter or parameters are of most significance. The simulation of the sound field in a 2-D 'water-steel' model is obtained using a Spatial Fourier Analysis method. The effects of incident angle, standoff, the aperture and the center frequency of the transducer were studied. Results show that the aperture of the transducer, the center frequency and the incident angle are the most important factors in controlling the directivity of the resulting LCR wave fields.

  11. Longitudinal charge nurse leadership development and evaluation.

    Science.gov (United States)

    Krugman, Mary; Heggem, Laura; Kinney, Lisa Judd; Frueh, Margaret

    2013-09-01

    The study's aim was to examine longitudinal outcomes of a leadership program for permanent and relief charge nurse from 1996 to 2012 using action research and Kouzes and Posner's The Leadership Challenge conceptual frameworks. Charge nurses hold significant oversight of patient safety, quality, and team functioning. This study contributes knowledge regarding charge nurse leadership and organization outcomes associated with these essential roles over time. Data were collected over 6 time periods using Kouzes and Posner's The Leadership Practices Inventory (LPI) and internally developed action research tools. Surveys were aligned with leadership and work environment changes to examine outcomes. Charge nurse leadership LPI mean ratings improved. Relief charge nurses reached similar LPI outcomes by 2012, with no statistical differences in mean or domain scores. Action research methods facilitated executive decision making during change processes. Demographics shifted with younger charge nurses with less practice experience serving as charge nurses in the most recent years. Charge nurse leadership reported significant gains despite institutional changes and uneven delivery of educational interventions.

  12. Longitudinal morphometric MRI study of Alzheimer's disease

    International Nuclear Information System (INIS)

    Ogomori, Koji; Takano, Koichi; Kuwabara, Yasuo; Nakano, Seigo; Nawata, Hideyuki; Yano, Rika; Nishimura, Ryoji; Takita, Masashi

    2009-01-01

    A longitudinal morphometric MRI study of Alzheimer's disease (AD) was conducted to determine the relationship between the progression of the symptoms and the progression of the brain atrophy. The Voxel-based Specific Regional Analysis System for Alzheimer's Disease (VSRAD), developed by Matsuda et al. was used as a method of morphometry to perform the statistical MR image analysis. Thirty-eight patients of AD patients were investigated with VSRAD. These patients were divided into two groups according to the progression of symptoms based on a clinical evaluation. One group was the progress group (20 patients), while the other group was the stable group (18 patients) for comparison. The relationship was investigated between the speed of the symptomatic progression and the change in each VSRAD indicator. Consequently, the entorhinal Z-score and the entorhinal atrophy rate showed a correlation with the speed of the symptomatic progression. The increase of the entorhinal Z-score in the follow-up was larger in the progress group than that in the stable group (0.65/1.28 years in the progress group and 0.05/1.26 years in the stable group.). These results suggest that a rapid symptomatic progression in an AD patient accompanies the rapid progression of atrophy in the entorhinal cortex. (author)

  13. Longitudinal growth changes in subjects with deepbite.

    Science.gov (United States)

    Baccetti, Tiziano; Franchi, Lorenzo; McNamara, James A

    2011-08-01

    This study was a cephalometric evaluation of the growth changes in untreated subjects with deepbite at 4 time points during their developmental ages (from the early mixed dentition to the permanent dentition, and from the prepubertal phase to young adulthood). A sample of 29 subjects with deepbite (overbite >4.5 mm) was followed longitudinally from about 9 through about 18 years of age. Dentofacial changes at 4 times, defined by the cervical vertebral maturation method, were analyzed on lateral cephalograms. Nonparametric statistical analysis was used for comparisons. Overbite improved on average by 1.3 mm between the first and last measurements; it worsened significantly during the prepubertal period, but it improved significantly at the pubertal growth spurt. From the prepubertal ages through young adulthood, overbite improved in 83% of the subjects and self-corrected in 62% of the subjects. Improvements in overbite were related to the initial amount of maxillary incisor proclination. The significant improvement in overbite during the adolescent growth spurt depended on the amount of vertical growth of the mandibular ramus and the eruption of the mandibular molars. Subjects with deepbite showed worsened occlusal conditions during the prepubertal and mixed dentition phases, but had significant improvements thereafter. Improvements in overbite cannot be predicted on the basis of skeletal vertical relationships. These results provide useful indications for appropriate orthodontic treatment timing for an increased overbite. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  14. A longitudinal analysis of nursing home outcomes.

    Science.gov (United States)

    Porell, F; Caro, F G; Silva, A; Monane, M

    1998-10-01

    To investigate resident and facility attributes associated with long-term care health outcomes in nursing homes. Quarterly Management Minutes Questionnaire (MMQ) survey data for Medicaid case-mix reimbursement of nursing homes in Massachusetts from 1991 to 1994, for specification of outcomes and resident attributes. Facility attributes are specified from cost report data. Multivariate logistic and "state-dependence" regression models are estimated for survival, ADL functional status, incontinence status, and mental status outcomes from longitudinal residence histories of Medicaid residents spanning 3 to 36 months in length. Outcomes are specified to be a function of resident demographic and diagnostic attributes and facility-level operating and nurse staffing attributes. The estimated parameters for resident demographic and diagnostic attributes showed a great deal of construct validity with respect to clinical expectations regarding risk factors for adverse outcomes. Few facility attributes were associated with outcomes generally, and none was significantly associated with all four outcomes. The absence of uniform associations between facility attributes and the various long-term care health outcomes studied suggests that strong facility performance on one health outcome may coexist with much weaker performance on other outcomes. This has implications for the aggregation of individual facility performance measures on multiple outcomes and the development of overall outcome performance measures.

  15. Transformation of QSPA plasma streams in longitudinal magnetic field

    International Nuclear Information System (INIS)

    Makhlaj, V.A.; Bandura, A.N.; Chebotarev, V.V.; Kulik, N.V.; Wuerz, H.

    2002-01-01

    The main aim of this work is analysis of efficiency of QSPA powerful plasma streams transportation in longitudinal magnetic field in dependence on operational mode of accelerator and plasma stream parameters

  16. Prediction of the development of reading comprehension: a longitudinal study

    NARCIS (Netherlands)

    Verhoeven, L.T.W.; Leeuwe, J.F.J. van

    2008-01-01

    Specific effects of word decoding, vocabulary and listening comprehension abilities on the development of reading comprehension were longitudinally examined for a representative sample of 2143 Dutch children throughout the elementary school period. An attempt was made to test two theoretical

  17. Horizontal-Longitudinal Correlations of Acoustic Field in Deep Water

    International Nuclear Information System (INIS)

    Li Jun; Li Zheng-Lin; Ren Yun; Li Wen; Zhang Ren-He

    2015-01-01

    The horizontal-longitudinal correlations of the acoustic field in deep water are investigated based on the experimental data obtained in the South China Sea. It is shown that the horizontal-longitudinal correlation coefficients in the convergence zone are high, and the correlation length is consistent with the convergence zone width, which depends on the receiver depth and range. The horizontal-longitudinal correlation coefficients in the convergence zone also have a division structure for the deeper receiver. The signals from the second part of the convergence zone are still correlated with the reference signal in the first part. The horizontal-longitudinal correlation coefficients in the shadow zone are lower than that in the convergence zone, and the correlation length in the shadow zone is also much shorter than that in the convergence zone. The numerical simulation results by using the normal modes theory are qualitatively consistent with the experimental results. (paper)

  18. Variable selection and estimation for longitudinal survey data

    KAUST Repository

    Wang, Li

    2014-09-01

    There is wide interest in studying longitudinal surveys where sample subjects are observed successively over time. Longitudinal surveys have been used in many areas today, for example, in the health and social sciences, to explore relationships or to identify significant variables in regression settings. This paper develops a general strategy for the model selection problem in longitudinal sample surveys. A survey weighted penalized estimating equation approach is proposed to select significant variables and estimate the coefficients simultaneously. The proposed estimators are design consistent and perform as well as the oracle procedure when the correct submodel was known. The estimating function bootstrap is applied to obtain the standard errors of the estimated parameters with good accuracy. A fast and efficient variable selection algorithm is developed to identify significant variables for complex longitudinal survey data. Simulated examples are illustrated to show the usefulness of the proposed methodology under various model settings and sampling designs. © 2014 Elsevier Inc.

  19. Dynamics of a longitudinal current during a magnetic storm

    International Nuclear Information System (INIS)

    Dolginov, S.Sh.; Zhuzgov, L.N.; Kosacheva, V.P.; Strunnikova, L.N.; Tyurmina, L.O.; Sharova, V.A.; Shkol'nikova, S.I.

    1984-01-01

    Results, investigating a spatial distribution and the structure of longitudinal currents during a magnetic storm at 18-19.09.81, are presented. It is shown that during the main phase of the storm the large-scale current system expands to the equator, and current density increases. Inside the current layer and to the pole of it there appears intensive small scale longitudinal l currents. During magnetic storm restopation phase the current system segregates into several pairs of opposite directed currents. During further decreasing of geomagnetic activity the large-scale current system is restored+ and its center is shifted to the pole, longitudinal current density being decreased. The invariant width of longitudinal currents is decreased, while the magnitude, Dsub(st), being increased, that is connected to the displacement of an auroral oval to the equator

  20. A New Kicker for the TLS Longitudinal Feedback System

    CERN Document Server

    Lau, Wai-Keung; Dehler, Micha; Hsu, Kuo-Tung; Hsu, San-Yuang; Jung Chou Ping; Wei Chen, Cheng; Yang Chen Huan; Yang Tze Te

    2005-01-01

    A new longitudinal kicker that is modified from the Swiss Light Source (SLS) design to fit into the TLS storage ring. It will be served as the actuator in the longitudinal multi-bunch feedback control loop. Beam coupling impedance has been calculated by Gdfidl with a PC cluster. Previous to the installation of this new kicker, bench measurement has been performed in the laboratory to characterize this new kicker. The experimental setups for bandwidth and coaxial wire measurement of longitudinal coupling impedance and their corresponding test results will be reported. As a cross check, bead-pull measurement has also been done to verify the beam coupling measurement by coaxial wire method at the kicker center frequency. Longitudinal field profile of the accelerating mode along the beam path has also been mapped. High order cavity modes of the kicker have also been observed and their effects on the beam are evaluated.

  1. Nonlinear correction to the longitudinal structure function at small x

    International Nuclear Information System (INIS)

    Boroun, G.R.

    2010-01-01

    We computed the longitudinal proton structure function F L , using the nonlinear Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (NLDGLAP) evolution equation approach at small x. For the gluon distribution, the nonlinear effects are related to the longitudinal structure function. As the very small-x behavior of the gluon distribution is obtained by solving the Gribov, Levin, Ryskin, Mueller and Qiu (GLR-MQ) evolution equation with the nonlinear shadowing term incorporated, we show that the strong rise that corresponds to the linear QCD evolution equations can be tamed by screening effects. Consequently, the obtained longitudinal structure function shows a tamed growth at small x. We computed the predictions for all details of the nonlinear longitudinal structure function in the kinematic range where it has been measured by the H1 Collaboration and made comparisons with the computation by Moch, Vermaseren and Vogt at the second order with input data from the MRST QCD fit. (orig.)

  2. Generalized latent variable modeling multilevel, longitudinal, and structural equation models

    CERN Document Server

    Skrondal, Anders; Rabe-Hesketh, Sophia

    2004-01-01

    This book unifies and extends latent variable models, including multilevel or generalized linear mixed models, longitudinal or panel models, item response or factor models, latent class or finite mixture models, and structural equation models.

  3. Multivariate longitudinal data analysis with mixed effects hidden Markov models.

    Science.gov (United States)

    Raffa, Jesse D; Dubin, Joel A

    2015-09-01

    Multiple longitudinal responses are often collected as a means to capture relevant features of the true outcome of interest, which is often hidden and not directly measurable. We outline an approach which models these multivariate longitudinal responses as generated from a hidden disease process. We propose a class of models which uses a hidden Markov model with separate but correlated random effects between multiple longitudinal responses. This approach was motivated by a smoking cessation clinical trial, where a bivariate longitudinal response involving both a continuous and a binomial response was collected for each participant to monitor smoking behavior. A Bayesian method using Markov chain Monte Carlo is used. Comparison of separate univariate response models to the bivariate response models was undertaken. Our methods are demonstrated on the smoking cessation clinical trial dataset, and properties of our approach are examined through extensive simulation studies. © 2015, The International Biometric Society.

  4. Longitudinal changes in microstructural white matter metrics in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Chantel D. Mayo

    2017-01-01

    Conclusion: The current results indicate that sensitivity to white matter microstructure is a promising avenue for AD biomarker research. Additional longitudinal studies on both white and grey matter are warranted to further evaluate potential clinical utility.

  5. Acquisition patterns of financial products : A longitudinal investigation

    NARCIS (Netherlands)

    Paas, Leonard J.; Bijmolt, Tammo H. A.; Vermunt, Jeroen K.

    Acquisition pattern analysis investigates orders in which households acquire products. Extant empirical studies employ cross-sectional data, providing limited insight into acquisition orders and no insight into timing of product acquisitions. We use an extensive longitudinal database for studying

  6. Generalized empirical likelihood methods for analyzing longitudinal data

    KAUST Repository

    Wang, S.; Qian, L.; Carroll, R. J.

    2010-01-01

    Efficient estimation of parameters is a major objective in analyzing longitudinal data. We propose two generalized empirical likelihood based methods that take into consideration within-subject correlations. A nonparametric version of the Wilks

  7. Application of multidimensional IRT models to longitudinal data

    NARCIS (Netherlands)

    te Marvelde, J.M.; Glas, Cornelis A.W.; Van Landeghem, Georges; Van Damme, Jan

    2006-01-01

    The application of multidimensional item response theory (IRT) models to longitudinal educational surveys where students are repeatedly measured is discussed and exemplified. A marginal maximum likelihood (MML) method to estimate the parameters of a multidimensional generalized partial credit model

  8. Latitudinal and longitudinal variation in aerosol characteristics from ...

    Indian Academy of Sciences (India)

    The physical and chemical properties of aerosols are strong ... Keywords. Aerosol optical characteristics; latitudinal and longitudinal variations; Bay of Bengal; Arabian Sea; pre- ...... of global sources of atmospheric soil dust identified with the ...

  9. Advantages and disadvantages : longitudinal vs. repeated cross-section surveys

    Science.gov (United States)

    1996-06-20

    The benefits of a longitudinal analysis over a repeated cross-sectional study include increased statistical power and the capability to estimate a greater range of conditional probabilities. With the Puget Sound Transportation Panel (PSTP), and any s...

  10. Dynamics of heavy ion beams during longitudinal compression

    International Nuclear Information System (INIS)

    Ho, D.D.M.; Bangerter, R.O.; Lee, E.P.; Brandon, S.; Mark, J.W.K.

    1987-01-01

    Heavy ion beams with initially uniform line charge density can be compressed longitudinally by an order of magnitude in such a way that the compressed beam has uniform line charge density and velocity-tilt profiles. There are no envelope mismatch oscillations during compression. Although the transverse temperature varies along the beam and also varies with time, no substantial longitudinal and transverse emittance growth has been observed. Scaling laws for beam radius and transport system parameters are given

  11. Simultaneous maximum a posteriori longitudinal PET image reconstruction

    Science.gov (United States)

    Ellis, Sam; Reader, Andrew J.

    2017-09-01

    Positron emission tomography (PET) is frequently used to monitor functional changes that occur over extended time scales, for example in longitudinal oncology PET protocols that include routine clinical follow-up scans to assess the efficacy of a course of treatment. In these contexts PET datasets are currently reconstructed into images using single-dataset reconstruction methods. Inspired by recently proposed joint PET-MR reconstruction methods, we propose to reconstruct longitudinal datasets simultaneously by using a joint penalty term in order to exploit the high degree of similarity between longitudinal images. We achieved this by penalising voxel-wise differences between pairs of longitudinal PET images in a one-step-late maximum a posteriori (MAP) fashion, resulting in the MAP simultaneous longitudinal reconstruction (SLR) method. The proposed method reduced reconstruction errors and visually improved images relative to standard maximum likelihood expectation-maximisation (ML-EM) in simulated 2D longitudinal brain tumour scans. In reconstructions of split real 3D data with inserted simulated tumours, noise across images reconstructed with MAP-SLR was reduced to levels equivalent to doubling the number of detected counts when using ML-EM. Furthermore, quantification of tumour activities was largely preserved over a variety of longitudinal tumour changes, including changes in size and activity, with larger changes inducing larger biases relative to standard ML-EM reconstructions. Similar improvements were observed for a range of counts levels, demonstrating the robustness of the method when used with a single penalty strength. The results suggest that longitudinal regularisation is a simple but effective method of improving reconstructed PET images without using resolution degrading priors.

  12. Longitudinal permittivity of a toroidal plasma near rational surfaces

    International Nuclear Information System (INIS)

    Nekrasov, F.M.

    1990-01-01

    A quite simple analytical formula for longitudinal permittivity, suitable for numerical processing on a computer, is determined. On the basis of a Fourier representation a poloidal angle a compact expression for the imaginary part of longitudinal permittivity near rational surfaces (m+nq=0) at an arbitrary relation between the bounce frequency and excited wave frequency is determined. A strongly magnetized collisionless plasma in the weak toroidality approximation is considered

  13. Longitudinal research and data collection in primary care.

    Science.gov (United States)

    van Weel, Chris

    2005-01-01

    This article reviews examples of and experience with longitudinal research in family medicine. The objective is to use this empirical information to formulate recommendations for improving longitudinal research. The article discusses 3 longitudinal studies from the Nijmegen academic family practice research network: 1 on the prognosis of depression and 1 each on the prognosis of and outcomes of care for type 2 diabetes mellitus. The Nijmegen network has recorded all episodes of morbidity encountered in Dutch family medicine since 1971 in a stable practice population. This network's experience is evaluated to identify lessons that may help other practice-based research networks (PBRNs) in pursuing longitudinal research. In terms of external conditions (conditions related to the general setting), the stability of a population and a high level of continuity of care substantially enhance the ability to perform longitudinal research. In terms of internal conditions (conditions related to the PBRN), motivation of family physicians and their staff to conduct ongoing data collection, and their ownership of the data are key for success. Other critical internal conditions include standardization of data; collection of data by clinician-friendly means; training of family physicians and their staff in data collection, as well as meetings for discussion of this task; provision of feedback to practices on the research findings; use of standard procedures to promote adherence to data collection; availability of facilities for regular measurement of patients' health status or chart review; and use of mechanisms for tracking patients who leave the practice area. Insight from existing experience suggests that longitudinal research can be enhanced in PBRNs. The best way forward is to build longitudinal data collection by drawing on lessons from successful studies. Primary care research policy should advocate for a role of longitudinal research and stimulate its development in PBRNs

  14. Causal mediation analysis for longitudinal data with exogenous exposure

    OpenAIRE

    Bind, M.-A. C.; Vanderweele, T. J.; Coull, B. A.; Schwartz, J. D.

    2015-01-01

    Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different type...

  15. Statistical methods for longitudinal data with agricultural applications

    DEFF Research Database (Denmark)

    Anantharama Ankinakatte, Smitha

    The PhD study focuses on modeling two kings of longitudinal data arising in agricultural applications: continuous time series data and discrete longitudinal data. Firstly, two statistical methods, neural networks and generalized additive models, are applied to predict masistis using multivariate...... algorithm. This was found to compare favourably with the algorithm implemented in the well-known Beagle software. Finally, an R package to apply APFA models developed as part of the PhD project is described...

  16. Transverse and longitudinal angular momenta of light

    Energy Technology Data Exchange (ETDEWEB)

    Bliokh, Konstantin Y., E-mail: k.bliokh@gmail.com [Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Nonlinear Physics Centre, RSPhysE, The Australian National University, Canberra, ACT 0200 (Australia); Nori, Franco [Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Physics Department, University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2015-08-26

    We review basic physics and novel types of optical angular momentum. We start with a theoretical overview of momentum and angular momentum properties of generic optical fields, and discuss methods for their experimental measurements. In particular, we describe the well-known longitudinal (i.e., aligned with the mean momentum) spin and orbital angular momenta in polarized vortex beams. Then, we focus on the transverse (i.e., orthogonal to the mean momentum) spin and orbital angular momenta, which were recently actively discussed in theory and observed in experiments. First, the recently-discovered transverse spin  angular momenta appear in various structured fields: evanescent waves, interference fields, and focused beams. We show that there are several kinds of transverse spin angular momentum, which differ strongly in their origins and physical properties. We describe extraordinary features of the transverse optical spins and overview recent experiments. In particular, the helicity-independent transverse spin inherent in edge evanescent waves offers robust spin–direction coupling at optical interfaces (the quantum spin Hall effect of light). Second, we overview the transverse orbital angular momenta of light, which can be both extrinsic and intrinsic. These two types of the transverse orbital angular momentum are produced by spatial shifts of the optical beams (e.g., in the spin Hall effect of light) and their Lorentz boosts, respectively. Our review is underpinned by a unified theory of the angular momentum of light based on the canonical momentum and spin densities, which avoids complications associated with the separation of spin and orbital angular momenta in the Poynting picture. It allows us to construct a comprehensive classification of all known optical angular momenta based on their key parameters and main physical properties.

  17. Magnetic characterisation of longitudinal thin film media

    International Nuclear Information System (INIS)

    Dova, P.

    1998-09-01

    Magnetic characterisation techniques, as applied to longitudinal thin film media, have been investigated. These included the study of the differentials of the remanence curves, the delta-M plot and the examination of the critical volumes. Several thin film structures, which are currently used or are being considered for future media applications, have been examined using these techniques. Most of the films were Co-alloys with the exception of a set of Barium ferrite films. Both monolayer and multilayer structures were studied. It was found that the study of activation volumes provides a better insight into the reversal mechanisms of magnetic media, especially in the case of complex structures such as multilayer films and films with bicrystal microstructure. Furthermore, an evaluation study of different methods of determining critical volumes showed that the method using time dependence measurements and the micromagnetic approach is the most appropriate. The magnetic characteristics of the thin film media under investigation were correlated with their microstructure and, where possible, with their noise performance. Magnetic force microscopy was also used for acquiring quasi-domain images in the ac-demagnetised state. It was found that in all Co-alloy films the dominant intergranular coupling is magnetising in nature, the level of which is governed by the Cr content in the magnetic layer. In the case of laminated media it was found that when non-magnetic spacers are used, the nature of the interlayer coupling depends on the spacer thickness. In double layer structures with no spacer, the top layer replicates the crystallographic texture of the bottom layer, and the overall film properties are a combination of the two layers. In bicrystal films the coupling is determined by the Cr segregation in the grain boundaries. Furthermore, the presence of stacking faults in bicrystal films deteriorates their thermal stability, but can be prevented by improving the epitaxial

  18. Longitudinal Association of Dementia and Depression.

    Science.gov (United States)

    Snowden, Mark B; Atkins, David C; Steinman, Lesley E; Bell, Janice F; Bryant, Lucinda L; Copeland, Catherine; Fitzpatrick, Annette L

    2015-09-01

    Depression is an important precursor to dementia, but less is known about the role dementia plays in altering the course of depression. We examined whether depression prevalence, incidence, and severity are higher in those with dementia versus those with mild cognitive impairment (MCI), or normal cognition. Prospective cohort study using the longitudinal Uniform Data Set of the National Alzheimer's Coordinating Center (2005-2013). 34 Alzheimer Disease research centers. 27,776 subjects with dementia, MCI, or normal cognition. Depression status was determined by a clinical diagnosis of depression within the prior 2 years and by a Geriatric Depression Scale-Short Form score >5. Rates of depression were significantly higher in subjects with MCI and dementia compared with those with normal cognition at index visit. Controlling for demographics and common chronic conditions, logistic regression analysis revealed elevated depression in those with MCI (OR: 2.40 [95% CI: 2.25, 2.56]) or dementia (OR: 2.64 [95% CI: 2.43, 2.86]) relative to those with normal cognition. In the subjects without depression at the index visit (N = 18,842), those with MCI and dementia had higher probabilities of depression diagnosis 2 years post index visit than those with normal cognition: MCI = 21.7%, dementia = 24.7%, normal cognition = 10.5%. MCI and dementia were associated with significantly higher rates of depression in concurrent as well as prospective analyses. These findings suggest that efforts to effectively engage and treat older adults with dementia will need also to address co-occurring depression. Copyright © 2015 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

  19. Longitudinal and bulk viscosities of Lennard-Jones fluids

    Science.gov (United States)

    Tankeshwar, K.; Pathak, K. N.; Ranganathan, S.

    1996-12-01

    Expressions for the longitudinal and bulk viscosities have been derived using Green Kubo formulae involving the time integral of the longitudinal and bulk stress autocorrelation functions. The time evolution of stress autocorrelation functions are determined using the Mori formalism and a memory function which is obtained from the Mori equation of motion. The memory function is of hyperbolic secant form and involves two parameters which are related to the microscopic sum rules of the respective autocorrelation function. We have derived expressions for the zeroth-, second-and fourth- order sum rules of the longitudinal and bulk stress autocorrelation functions. These involve static correlation functions up to four particles. The final expressions for these have been put in a form suitable for numerical calculations using low- order decoupling approximations. The numerical results have been obtained for the sum rules of longitudinal and bulk stress autocorrelation functions. These have been used to calculate the longitudinal and bulk viscosities and time evolution of the longitudinal stress autocorrelation function of the Lennard-Jones fluids over wide ranges of densities and temperatures. We have compared our results with the available computer simulation data and found reasonable agreement.

  20. Longitudinal beam compression for heavy-ion inertial fusion

    International Nuclear Information System (INIS)

    Ho, D.D.M.; Brandon, S.T.

    1991-01-01

    A scheme is described for compressing a heavy-ion beam longitudinally in such a way that the compressed pulse has uniform line-charge density and longitudinal momentum. Attaining these conditions will be important in the final focusing of a beam on a small fuel capsule in an inertial confinement fusion reactor. The longitudinal dynamics can be approximately described by a one-dimensional (1-D) fluid model for charged particles. Recognizing the similarity between the 1-D charged particle equations of motion and the 1-D equations for ideal-gas flow permits us to calculate the evolution of the line-charge density and velocity profile using self-similar solutions and the method of characteristics, developed for unsteady supersonic gas dynamics, for different regions along the beam. Simple physical arguments show that although the longitudinal and transverse temperatures vary along the beam following the adiabatic laws, no substantial longitudinal and transverse emittance growth is to be expected. Particle-in-cell simulations confirm all the physical arguments. The compressed beam has negligible longitudinal momentum spread and can therefore avoid chromatic aberrations in final focus. (author) 24 refs., 5 figs., 1 tab

  1. Longitudinal changes in white matter microstructure after heavy cannabis use

    Directory of Open Access Journals (Sweden)

    Mary P. Becker

    2015-12-01

    Full Text Available Diffusion tensor imaging (DTI studies of cannabis users report alterations in brain white matter microstructure, primarily based on cross-sectional research, and etiology of the alterations remains unclear. We report findings from longitudinal voxelwise analyses of DTI data collected at baseline and at a 2-year follow-up on 23 young adult (18–20 years old at baseline regular cannabis users and 23 age-, sex-, and IQ-matched non-using controls with limited substance use histories. Onset of cannabis use was prior to age 17. Cannabis users displayed reduced longitudinal growth in fractional anisotropy in the central and parietal regions of the right and left superior longitudinal fasciculus, in white matter adjacent to the left superior frontal gyrus, in the left corticospinal tract, and in the right anterior thalamic radiation lateral to the genu of the corpus callosum, along with less longitudinal reduction of radial diffusion in the right central/posterior superior longitudinal fasciculus, corticospinal tract, and posterior cingulum. Greater amounts of cannabis use were correlated with reduced longitudinal growth in FA as was relatively impaired performance on a measure of verbal learning. These findings suggest that continued heavy cannabis use during adolescence and young adulthood alters ongoing development of white matter microstructure, contributing to functional impairment.

  2. Longitudinal drop-out and weighting against its bias

    Directory of Open Access Journals (Sweden)

    Steffen C. E. Schmidt

    2017-12-01

    Full Text Available Abstract Background The bias caused by drop-out is an important factor in large population-based epidemiological studies. Many studies account for it by weighting their longitudinal data, but to date there is no detailed final approach for how to conduct these weights. Methods In this study we describe the observed longitudinal bias and a three-step longitudinal weighting approach used for the longitudinal data in the MoMo baseline (N = 4528, 4–17 years and wave 1 study with 2807 (62% participants between 2003 and 2012. Results The most meaningful drop-out predictors were socioeconomic status of the household, socioeconomic characteristics of the mother and daily TV usage. Weighting reduced the bias between the longitudinal participants and the baseline sample, and also increased variance by 5% to 35% with a final weighting efficiency of 41.67%. Conclusions We conclude that a weighting procedure is important to reduce longitudinal bias in health-oriented epidemiological studies and suggest identifying the most influencing variables in the first step, then use logistic regression modeling to calculate the inverse of the probability of participation in the second step, and finally trim and standardize the weights in the third step.

  3. Modelling, simulation and applications of longitudinal train dynamics

    Science.gov (United States)

    Cole, Colin; Spiryagin, Maksym; Wu, Qing; Sun, Yan Quan

    2017-10-01

    Significant developments in longitudinal train simulation and an overview of the approaches to train models and modelling vehicle force inputs are firstly presented. The most important modelling task, that of the wagon connection, consisting of energy absorption devices such as draft gears and buffers, draw gear stiffness, coupler slack and structural stiffness is then presented. Detailed attention is given to the modelling approaches for friction wedge damped and polymer draft gears. A significant issue in longitudinal train dynamics is the modelling and calculation of the input forces - the co-dimensional problem. The need to push traction performances higher has led to research and improvement in the accuracy of traction modelling which is discussed. A co-simulation method that combines longitudinal train simulation, locomotive traction control and locomotive vehicle dynamics is presented. The modelling of other forces, braking propulsion resistance, curve drag and grade forces are also discussed. As extensions to conventional longitudinal train dynamics, lateral forces and coupler impacts are examined in regards to interaction with wagon lateral and vertical dynamics. Various applications of longitudinal train dynamics are then presented. As an alternative to the tradition single wagon mass approach to longitudinal train dynamics, an example incorporating fully detailed wagon dynamics is presented for a crash analysis problem. Further applications of starting traction, air braking, distributed power, energy analysis and tippler operation are also presented.

  4. Crecimiento longitudinal posnatal del primer metatarsiano. [Longitudinal postnatal growth of the first metatarsal bone

    Directory of Open Access Journals (Sweden)

    Julio J. Masquijo

    2014-10-01

    Full Text Available Introducción: si bien el crecimiento prenatal y posnatal del pie ha sido documentado hace varios años, el crecimiento longitudinal del primer metatarsiano en particular no ha sido estudiado previamente. El objetivo del estudio es determinar el patrón de crecimiento longitudinal posnatal de este hueso y compararlo con el del pie y los huesos largos del miembro inferior. Materiales y Métodos: mediante una búsqueda informatizada, se identificaron pacientes <18 años de edad con radiografías informadas como “normal” por el radiólogo. Se analizó una muestra de 886 pacientes divididos en 18 grupos según la edad (0-11 meses, 1 año, 2 años, etc. y el sexo. El análisis de las imágenes se realizó con un software de imágenes Kodak Carestream PACS. Resultados: el largo promedio en el primer grupo fue de 19,91 mm (3,20; 15,22-25,62. El largo promedio en el último grupo fue de 66,13 mm (5,33; 52,50-77,18. La tasa de crecimiento anual fue de 2,71 mm. La edad promedio al momento del cierre de la fisis fue de 14.85 años (± 1.64 para los varones y 14.77 años (± 3.63 para las niñas. Conclusión: el crecimiento del primer metatarsiano acompaña el crecimiento longitudinal del pie, pero no el de los huesos largos del miembro inferior. Las curvas de crecimiento del primer metatarsiano descritas en este artículo pueden ser aplicadas en patologías que afectan el desarrollo del pie o que requieren cirugía de corrección sobre el primer metatarsiano, o se las puede emplear como estándar de referencia en futuros estudios.

  5. LONGITUDINAL STUDIES OF MUSICALLY GIFTED SCHOOLGIRLS

    Directory of Open Access Journals (Sweden)

    Svetlana N. Loseva

    2016-01-01

    Full Text Available The aim of the article is to consider the empirical aspects of the development of musical gifted schoolgirls in vocal and choral activities.Methods. Scientific methods of research (observation, questionnaire, interview, formative experiment, longitude, testing are used. Data are analyzed using a complex of psychodiagnostic techniques: culture and free intelligence test by R. Cattell; the modified creative test by F. Williams; personal multifactorial questionnaire by R. Cattell. The reliability of the results and the validity of the findings is provided by the use of reliable and proven in the domestic and foreign psychology methods and techniques, using different statistical methods of data processing, the definition of parametric and non-parametric statistical tests (Student’s t-criterion, Spearman’s rank correlation, criterion U-Mann – Whitney, criterion T-Wilcoxon, L-criterion trends Page.Results and scientific novelty. Results of longitudinal research of development of musical aptitude are presented. Experimental work in which schoolgirls of 8–15 years participated, was carried out on the basis of creative choral collectives of Irkutsk within three years. Features of development of the pupils who are engaged in singing are revealed. It is established that in process of development of specially developed program (comprehension of emotional and semantic aspects of perception of a piece of music, finding of ability to distinguish musical timbres and the general coloring of sounding etc. analytical and intonation hearing improves under pupils’ age. Regular long singing trainings promote formation of cogitative operations: active development of divergent, rational and logical thinking and intelligence in general, and also acquisition of skills of a self-assessment. Besides, such occupations dispose children and teenagers to emotional responsiveness and spiritual self-improvement.Practical significance. The research

  6. Thoracic posterior longitudinal ligament ossification in a fixed population; longitudinal radiological observations

    International Nuclear Information System (INIS)

    Ono, Minoru; Russell, W.J.; Kudo, Sho.

    1984-05-01

    All lateral chest radiographs of 34 persons with posterior longitudinal ligament ossification (PLLO) in the thoracic spine were reviewed for date of its onset and its progress. These observations spanned as long as 18 years. Upper mid-thoracic PLLO first appeared under the age of 40, then increased in extent in the vertical axis until the age of 50. Lower thoracic PLLO occurred later than upper mid-thoracic PLLO. In the lower thoracic and lumbar regions, degeneration of the vertebrae and discs apparently were focal factors which triggered the development of thoracic PLLO. PLLO apparently developed in a different way in the upper and mid-thoracic regions, where the vertebrae and discs were unremarkable at the time of its initial appearance, and degenerative abnormalities did not predispose to it. (author)

  7. Indicadores precoces da dislexia de desenvolvimento: um estudo longitudinal || Early indicators of dyslexia: a longitudinal study

    Directory of Open Access Journals (Sweden)

    Anabela Carvalho

    2017-12-01

    Full Text Available A dislexia do desenvolvimento é frequentemente diagnosticada quando os problemas na aprendizagem da leitura já afetaram negativamente outras áreas académicas e até o bem-estar emocional. A pesquisa internacional aponta para a existência de alguns preditores desta perturbação da aprendizagem, permitindo uma intervenção atempada e preventiva. No entanto, as diferenças relativas ao código ortográfico do Português Europeu não nos permitem tirar ilações de estudos realizados noutros contextos linguísticos. Com este problema em mente, desenvolvemos um estudo longitudinal que pretende destacar os preditores da dislexia em crianças portuguesas. A investigação seguiu um plano longitudinal ao longo de três anos e os resultados obtidos junto de uma amostra de 200 crianças permitem identificar a existência de poder preditivo em duas variáveis: no conhecimento que a criança tem do nome das letras e no seu desempenho em tarefas de fluência verbal, mostrando a influência que os fatores relativos às dificuldades na aquisição do princípio alfabético e no acesso ao léxico terão na manifestação posterior de problemas na aquisição da leitura.

  8. Comparison of torsional and longitudinal modes using phacoemulsification parameters.

    Science.gov (United States)

    Rekas, Marek; Montés-Micó, Robert; Krix-Jachym, Karolina; Kluś, Adam; Stankiewicz, Andrzej; Ferrer-Blasco, Teresa

    2009-10-01

    To compare phacoemulsification parameters of torsional and longitudinal ultrasound modes. Ophthalmology Department, Military Health Service Institute, Warsaw, Poland. This prospective study evaluated eyes 1, 7, and 30 days after phacoemulsification with an Infiniti Vision System using the torsional or longitudinal ultrasound (US) mode. Cataract classification was according to the Lens Opacities Classification System II. Nucleus fragmentation was by the phaco-chop and quick-chop methods. Primary outcome measures were phaco time, mean phaco power, mean torsional amplitude, and aspiration time. Total energy, defined as cumulative dissipated energy (CDE) x aspiration time, and the effective coefficient, defined as aspiration time/phaco time, were also calculated. Four hundred eyes were evaluated. The CDE was statistically significantly lower in the torsional mode for nucleus grades I, II, and III (P.05). Aspiration time was statistically significantly shorter in the torsional mode than in the longitudinal mode for nucleus grades III and IV (P<.05). Total energy was significantly lower in the torsional mode for all nucleus densities (P<.05). The effective coefficient was significantly lower in the longitudinal mode except for nucleus grade I (P<.05). Torsional phacoemulsification was more effective than longitudinal phacoemulsification in the amount of applied fluid and the quantity of US energy expended. With the torsional method, it was possible to maintain a constant ratio of amount of fluid flow to quantity of US energy used, regardless of nucleus density.

  9. Simulation of the ALS longitudinal multibunch feedback system

    International Nuclear Information System (INIS)

    Byrd, J.

    1993-05-01

    Longitudinal coupled bunch growth rates in the Advanced Light Source (ALS), a 1.5 GeV electron storage ring for producing synchrotron radiation, indicate the need for damping via a feedback (FB) system. The design of the system is based on the proposed PEP-II longitudinal FB system which uses a digital filter to provide the required phase and amplitude response. We report the results of a detailed computer simulation of the FB system including single particle longitudinal beam dynamics, measured RF cavity fundamental and higher order modes, and response of major FB components such as the power amplifier and kicker. The simulation addresses issues such as required FB power and gain, noise, digital filter effects, and varying initial bunch conditions

  10. Longitudinal Bunch Position Control for the Super-B Accelerator

    International Nuclear Information System (INIS)

    Bertsche, Kirk; Rivetta, Claudio; Sullivam, Michael K.; SLAC; Drago, Alessandro; Frascati

    2009-01-01

    The use of normal conducting cavities and an ion-clearing gap will cause a significant RF accelerating voltage gap transient and longitudinal phase shift of the individual bunches along the bunch train in both rings of the SuperB accelerator. Small relative centroid position shifts between bunches of the colliding beams will have a large adverse impact on the luminosity due to the small β* y at the interaction point (IP). We investigate the possibility of minimizing the relative longitudinal position shift between bunches by reducing the gap transient in each ring and matching the longitudinal bunch positions of the two rings at the IP using feedback/feedforward techniques in the LLRF. The analysis is conducted assuming maximum use of the klystron power installed in the system

  11. Longitudinal coupled-bunch instability studies in the PS

    CERN Document Server

    Damerau, H

    2017-01-01

    The main longitudinal limitation for LHC-type beams inthe PS are coupled-bunch instabilities. A dedicated proto-typefeedbacksystemusingaFinemetcavityasalongitudinalkicker has been installed. Extensive tests with beam havebeen performed to explore the intensity reach with this feed-back. The maximum intensity with nominal longitudinalemittance at PS extraction has been measured, as well as theemittance required to keep the beam longitudinally stableat the design intensity for the High-Luminosity LHC (HL-LHC). A higher-harmonic cavity is a complementary op-tion to extend the intensity reach beyond the capabilities ofthe coupled-bunch feedback. Preliminary machine develop-ment (MD) studies operating one20MHzor one40MHzRF system as a higher harmonic at the flat-top indicate thebeneficial effect on longitudinal beam stability

  12. Longitudinal Jitter Analysis of a Linear Accelerator Electron Gun

    Directory of Open Access Journals (Sweden)

    MingShan Liu

    2016-11-01

    Full Text Available We present measurements and analysis of the longitudinal timing jitter of a Beijing Electron Positron Collider (BEPCII linear accelerator electron gun. We simulated the longitudinal jitter effect of the gun using PARMELA to evaluate beam performance, including: beam profile, average energy, energy spread, and XY emittances. The maximum percentage difference of the beam parameters is calculated to be 100%, 13.27%, 42.24% and 65.01%, 86.81%, respectively. Due to this, the bunching efficiency is reduced to 54%. However, the longitudinal phase difference of the reference particle was 9.89°. The simulation results are in agreement with tests and are helpful to optimize the beam parameters by tuning the trigger timing of the gun during the bunching process.

  13. Using administrative data for longitudinal substance abuse research.

    Science.gov (United States)

    Evans, Elizabeth; Grella, Christine E; Murphy, Debra A; Hser, Yih-Ing

    2010-04-01

    The utilization of administrative data in substance abuse research has become more widespread than ever. This selective review synthesizes recent extant research from 31 articles to consider what has been learned from using administrative data to conduct longitudinal substance abuse research in four overlapping areas: (1) service access and utilization, (2) underrepresented populations, (3) treatment outcomes, and (4) cost analysis. Despite several notable limitations, administrative data contribute valuable information, particularly in the investigation of service system interactions and outcomes among substance abusers as they unfold and influence each other over the long term. This critical assessment of the advantages and disadvantages of using existing administrative data within a longitudinal framework should stimulate innovative thinking regarding future applications of administrative data for longitudinal substance abuse research purposes.

  14. Longitudinal-bending mode micromotor using multilayer piezoelectric actuator.

    Science.gov (United States)

    Yao, K; Koc, B; Uchino, K

    2001-07-01

    Longitudinal-bending mode ultrasonic motors with a diameter of 3 mm were fabricated using stacked multilayer piezoelectric actuators, which were self-developed from hard lead zirconate titanate (PZT) ceramic. A bending vibration was converted from a longitudinal vibration with a longitudinal-bending coupler. The motors could be bidirectionally operated by changing driving frequency. Their starting and braking torque were analyzed based on the transient velocity response. With a load of moment of inertia 2.5 x 10(-7) kgm2, the motor showed a maximum starting torque of 127.5 microNm. The braking torque proved to be a constant independent on the motor's driving conditions and was roughly equivalent to the maximum starting torque achievable with our micromotors.

  15. Nonlinear Cascade Strategy for Longitudinal Control of Electric Vehicle.

    Science.gov (United States)

    El Majdoub, K; Giri, F; Ouadi, H; Chaoui, F Z

    2014-01-01

    The problem of controlling the longitudinal motion of front-wheels electric vehicle (EV) is considered making the focus on the case where a single dc motor is used for both front wheels. Chassis dynamics are modelled applying relevant fundamental laws taking into account the aerodynamic effects and the road slope variation. The longitudinal slip, resulting from tire deformation, is captured through Kiencke's model. Despite its highly nonlinear nature the complete model proves to be utilizable in longitudinal control design. The control objective is to achieve a satisfactory vehicle speed regulation in acceleration/deceleration stages, despite wind speed and other parameters uncertainty. An adaptive controller is developed using the backstepping design technique. The obtained adaptive controller is shown to meet its objectives in presence of the changing aerodynamics efforts and road slope.

  16. Longitudinal intensity effects in the CERN Large Hadron Collider

    CERN Document Server

    AUTHOR|(CDS)2081238; Rivkin, Leonid

    This PhD thesis provides an improved knowledge of the LHC longitudinal impedance model and a better understanding of the longitudinal intensity effects. These effects can limit the LHC performance and lead to a reduction of the integrated luminosity. The LHC longitudinal impedance was measured with beams. Results obtained using traditional techniques are consistent with the expectations based on the impedance model, although the measurement precision was proven insufficient for the low impedance of the LHC. Innovative methods to probe the LHC reactive impedance were successfully used. One of the methods is based on exciting the beam with a sinusoidal rf phase modulation to estimate the synchrotron frequency shift from potential-well distortion. In the second method, the impedance is estimated from the loss of Landau damping threshold, which is also found to be in good agreement with analytical estimations. Beam-based impedance measurements agree well with estimations using the LHC impedance model. Macropartic...

  17. Longitudinal tire force estimation based on sliding mode observer

    Energy Technology Data Exchange (ETDEWEB)

    El Hadri, A.; Cadiou, J.C.; M' Sirdi, N.K. [Versailles Univ., Paris (France). Lab. de Robotique; Beurier, G.; Delanne, Y. [Lab. Central des Ponts, Centre de Nantes (France)

    2001-07-01

    This paper presents an estimation method for vehicle longitudinal dynamics, particularly the tractive/braking force. The estimation can be used to detect a critical driving situation to improve security. It can be used also in several vehicle control systems. The main characteristics of the vehicle longitudinal dynamics were taken into account in the model used to design an observer and computer simulations. The state variables are the angular wheel velocity, vehicle velocity and the longitudinal tire force. The proposed differential equation of the tractive/braking force is derived using the concept of relaxation length. The observer designed is based on the sliding mode approach using only the angular wheel velocity measurement. The proposed method of estimation is verified through a one-wheel simulation model with a ''Magic formula'' tire model. Simulations results show an excellent reconstruction of the tire force. (orig.)

  18. Correlative roentgenography and morphology of the longitudinal epiphyseal bracket

    International Nuclear Information System (INIS)

    Ogden, J.A.; Light, T.R.; Conlogue, G.J.; Yale Univ., New Haven, CT

    1981-01-01

    Detailed examination of a complete chondro-osseous specimen from a patient with duplication of the first ray of the foot revealed the involved metatarsal had a trapezoid-shaped, diaphyseal-metaphyseal osseous unit that was longitudinally bracketed along the lateral side by a functioning physis, epiphysis, and secondary (epiphyseal) ossification center. The physis extended as an arc from the medial proximal side toward and along the lateral side and then back to the medial side distally. The medial side of the diaphysis had a normal periosteum. The longitudinal epiphyseal ossification bracket was a composite of initially separate proximal and distal secondary ossification centers that had progressively extended toward each other and finally coalesced along the laterally placed epiphyseal cartilage. We have termed this deformity the 'longitudinal epiphyseal bracket' (LEB). The macroscopic and microscopic anatomy relevant to initial diagnosis and evaluation of sequential roentgenographic changes will be considered. (orig.)

  19. Structure functions of longitudinal virtual photons at low virtualities

    International Nuclear Information System (INIS)

    Ioffe, B.L.; Shushpanov, I.A.

    1996-01-01

    The structure functions F L 1 and F L 2 of longitudinal virtual photons at low virtualities are calculated in the framework of chiral perturbation theory (ChPT) in the zero and first order of ChPT. It is assumed that the virtuality of a target longitudinal photon p 2 is much less than the virtuality of the hard projectile photon Q 2 and both are less than the characteristic ChPT scale. In this approximation the structure functions are determined by the production of two pions in γγ collisions. The numerical results for F L 2 and F L 1 are presented (the upper index refers to the longitudinal polarization of the virtual target photon). The possibilities of measurements of these structure functions are briefly discussed. copyright 1996 The American Physical Society

  20. Improved Longitudinal Blow-up and Shaving in the Booster

    CERN Document Server

    Hancock, S

    2013-01-01

    The low-intensity proton beam for p-Pb collisions in the LHC did not come back in the Booster at the beginning of 2013 anything like it had been set up at the end of 2012. In particular there were unexplained intensity fluctuations of ±100%. Although the root cause of the drift in performance was never established, its investigation revealed long-standing issues in the longitudinal plane which, when corrected, allowed single-bunch beams to be delivered with unprecedented reproducibility and control of both intensity and longitudinal emittance. The new approach was adopted for the ion run and subsequently for MDs at higher intensities, where it made possible a robust control of intensity at constant 6D phase space volume. Post-LS1, it may even provide a platform upon which to build a more exotic controlled longitudinal blow-up to generate higher intensity bunches with a flattened line density.

  1. Control of longitudinal collective behavior in the Muon Collider rings

    International Nuclear Information System (INIS)

    Cheng, Wen-Hao

    1997-05-01

    The longitudinal bunch collective effects in a Muon Collider ring are theoretically examined. The situation involves an intense bunch, a short bunch, a small momentum compaction, a rather large impedance compared with the stability threshold criterion, and luminosity life time limited by muon decay to a thousand turns. Qualitative descriptions of stability are given and a scaling law for the instability threshold is derived. Numerical simulation results for the impedance-related instabilities are given for two cases of current interest - a 250 GeV x 250 GeV demonstration machine and a 2 TeV x 2 TeV high energy machine. The results of these simulations are in good agreement with the predictions of the scaling law and show that the longitudinal collective effects are controllable with a proper choice of parameters (viz. rf voltage, rf frequency, linear and non-linear longitudinal chromaticity)

  2. The dorsal tectal longitudinal column (TLCd): a second longitudinal column in the paramedian region of the midbrain tectum.

    Science.gov (United States)

    Aparicio, M-Auxiliadora; Saldaña, Enrique

    2014-03-01

    The tectal longitudinal column (TLC) is a longitudinally oriented, long and narrow nucleus that spans the paramedian region of the midbrain tectum of a large variety of mammals (Saldaña et al. in J Neurosci 27:13108-13116, 2007). Recent analysis of the organization of this region revealed another novel nucleus located immediately dorsal, and parallel, to the TLC. Because the name "tectal longitudinal column" also seems appropriate for this novel nucleus, we suggest the TLC described in 2007 be renamed the "ventral tectal longitudinal column (TLCv)", and the newly discovered nucleus termed the "dorsal tectal longitudinal column (TLCd)". This work represents the first characterization of the rat TLCd. A constellation of anatomical techniques was used to demonstrate that the TLCd differs from its surrounding structures (TLCv and superior colliculus) cytoarchitecturally, myeloarchitecturally, neurochemically and hodologically. The distinct expression of vesicular amino acid transporters suggests that TLCd neurons are GABAergic. The TLCd receives major projections from various areas of the cerebral cortex (secondary visual mediomedial area, and granular and dysgranular retrosplenial cortices) and from the medial pretectal nucleus. It densely innervates the ipsilateral lateral posterior and laterodorsal nuclei of the thalamus. Thus, the TLCd is connected with vision-related neural centers. The TLCd may be unique as it constitutes the only known nucleus made of GABAergic neurons dedicated to providing massive inhibition to higher order thalamic nuclei of a specific sensory modality.

  3. Measurements of longitudinal phase space in the SLC linac

    International Nuclear Information System (INIS)

    Bane, K.; Adolphsen, C.; Lavine, T.L.; Ross, M.; Seeman, J.; Thompson, K.

    1990-05-01

    In the Stanford Linear Collider the beam leaves a damping ring and then enters the Ring-to-Linac (RTL) transfer line. In the RTL it is compressed in length by a factor of 10 by means of an rf section, with which a longitudinally correlated energy variation is induced in the beam, and a following beam line which has non-zero momentum compaction. The compressed beam then enters the linac proper. In this paper we describe three measurements of longitudinal properties of the beam in the SLC linac. We present measurements of single bunch beam loading, of the energy spectrum at the end of the linac, and of the linac bunch length. Since the results of all three measurements depend on the beam's longitudinal charge distribution in the linac they, in turn, also depend on the bunch lengthening that occurs in the damping rings, as well as on the behavior of the compressor. The results of the first two measurements, in addition, depend critically on the strength of the longitudinal wakefields in the linac. The results of these three measurements are compared with simulations. For these calculations, at any given current, the potential well distortion in the damping ring is first computed. The compression process is then simulated to obtain the longitudinal charge distribution in the linac. For the first two measurements this distribution is then convolved with the calculated longitudinal wake function of the SLAC linac in order to obtain the induced voltage. Finally, the induced voltage is combined with the effect of the linac rf wave to give the final energy spectrum. 8 refs., 5 figs

  4. The re-identification risk of Canadians from longitudinal demographics

    Science.gov (United States)

    2011-01-01

    Background The public is less willing to allow their personal health information to be disclosed for research purposes if they do not trust researchers and how researchers manage their data. However, the public is more comfortable with their data being used for research if the risk of re-identification is low. There are few studies on the risk of re-identification of Canadians from their basic demographics, and no studies on their risk from their longitudinal data. Our objective was to estimate the risk of re-identification from the basic cross-sectional and longitudinal demographics of Canadians. Methods Uniqueness is a common measure of re-identification risk. Demographic data on a 25% random sample of the population of Montreal were analyzed to estimate population uniqueness on postal code, date of birth, and gender as well as their generalizations, for periods ranging from 1 year to 11 years. Results Almost 98% of the population was unique on full postal code, date of birth and gender: these three variables are effectively a unique identifier for Montrealers. Uniqueness increased for longitudinal data. Considerable generalization was required to reach acceptably low uniqueness levels, especially for longitudinal data. Detailed guidelines and disclosure policies on how to ensure that the re-identification risk is low are provided. Conclusions A large percentage of Montreal residents are unique on basic demographics. For non-longitudinal data sets, the three character postal code, gender, and month/year of birth represent sufficiently low re-identification risk. Data custodians need to generalize their demographic information further for longitudinal data sets. PMID:21696636

  5. ABRUPT LONGITUDINAL MAGNETIC FIELD CHANGES IN FLARING ACTIVE REGIONS

    International Nuclear Information System (INIS)

    Petrie, G. J. D.; Sudol, J. J.

    2010-01-01

    We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within 65 0 of disk center using 1 minute GONG magnetograms. In all 77 cases, we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of ∼10 G to as high as ∼450 G in two exceptional cases. The median value was 69 G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100 G tended to decrease longitudinal field strengths, both close to disk center and close to the limb, while field changes greater than 100 G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux changes, particularly net flux changes near disk center, correlated better than local field changes with GOES peak X-ray flux. The strongest longitudinal field and flux changes occurred in flares observed close to the limb. We estimate the change of Lorentz force associated with each flare and find that this is large enough in some cases to power seismic waves. We find that longitudinal field decreases would likely outnumber increases at all parts of the solar disk within 65 0 of disk center, as in our observations, if photospheric field tilts increase during flares as predicted by Hudson et al.

  6. Longitudinal tracking with phase and amplitude modulated rf

    International Nuclear Information System (INIS)

    Caussyn, D.D.; Ball, M.; Brabson, B.

    1993-06-01

    Synchrotron motion was induced by phase shifting the rf of the Indiana University Cyclotron Facility (IUCF) cooler-synchrotron. The resulting coherent-bunch motion was tracked in longitudinal phase space for as many as 700,000 turns, or for over 350 synchrotron oscillations. Results of recent experimental studies of longitudinal motion in which the rf phase and amplitude were harmonically modulated are also presented. Comparisons of experimental data with numerical simulations, assuming independent particle motion, are made. Observed multiparticle effects are also discussed

  7. Upper-extremity phocomelia reexamined: a longitudinal dysplasia.

    Science.gov (United States)

    Goldfarb, Charles A; Manske, Paul R; Busa, Riccardo; Mills, Janith; Carter, Peter; Ezaki, Marybeth

    2005-12-01

    In contrast to longitudinal deficiencies, phocomelia is considered a transverse, intercalated segmental dysplasia. Most patients demonstrate severe, but not otherwise classifiable, upper-extremity deformities, which usually cannot be placed into one of three previously described phocomelia groups. Additionally, these phocomelic extremities do not demonstrate true segmental deficits; the limb is also abnormal proximal and distal to the segmental defect. The purpose of this investigation was to present evidence that upper-extremity abnormalities in patients previously diagnosed as having phocomelia in fact represent a proximal continuum of radial or ulnar longitudinal dysplasia. The charts and radiographs of forty-one patients (sixty extremities) diagnosed as having upper-extremity phocomelia were reviewed retrospectively. On the basis of the findings on the radiographs, the disorders were categorized into three groups: (1) proximal radial longitudinal dysplasia, which was characterized by an absent proximal part of the humerus, a nearly normal distal part of the humerus, a completely absent radius, and a radial-sided hand dysplasia; (2) proximal ulnar longitudinal dysplasia, characterized by a short one-bone upper extremity that bifurcated distally and by severe hand abnormalities compatible with ulnar dysplasia; and (3) severe combined dysplasia, with type A characterized by an absence of the forearm segment (i.e., the radius and ulna) and type B characterized by absence of the arm and forearm (i.e., the hand attached to the thorax). Twenty-nine limbs in sixteen patients could be classified as having proximal radial longitudinal dysplasia. Systemic medical conditions such as thrombocytopenia-absent radius syndrome were common in those patients, but additional musculoskeletal conditions were rare. Twenty limbs in seventeen patients could be classified as having proximal ulnar longitudinal dysplasia. Associated musculoskeletal abnormalities, such as proximal femoral

  8. A Longitudinal Study of Usability in Health Care

    DEFF Research Database (Denmark)

    Kjeldskov, Jesper; Skov, Mikael B.; Stage, Jan

    2010-01-01

    We report from a longitudinal laboratory-based usability evaluation of a health care information system. The purpose of the study was to inquire into the nature of usability problems experienced by novice and expert users, and to see to what extend usability problems of a health care information...... system may or may not disappear over time, as the nurses get more familiar with it-if time heals poor design? As our method for studying this, we conducted a longitudinal study with two key studies. A usability evaluation was conducted with novice users when an electronic patient record system was being......, we discuss implications for evaluating usability in health care....

  9. Multi-longitudinal-mode micro-laser model

    Science.gov (United States)

    Staliunas, Kestutis

    2017-10-01

    We derive a convenient model for broad aperture micro-lasers, such as microchip lasers, broad area semiconductor lasers, or VCSELs, taking into account several longitudinal mode families. We provide linear stability analysis, and show characteristic spatio-temporal dynamics in such multi-longitudinal mode laser models. Moreover, we derive the coupled mode model in the presence of intracavity refraction index modulation (intracavity photonic crystal). Contribution to the Topical Issue "Theory and Applications of the Lugiato-Lefever Equation", edited by Yanne K. Chembo, Damia Gomila, Mustapha Tlidi, Curtis R. Menyuk.

  10. Process of magnetic reconnection as a source of longitudinal currents

    International Nuclear Information System (INIS)

    Sidneva, M.V.; Semenov, V.S.

    1987-01-01

    Variations in magnetic field and current system as applied to conditions in the Earth magnetospheric tail are calculated so as to show that three-dimensional reconnection leads inevitably to the appearance of a system of longitudinal currents. With reference to current layer of the magnetospheric tail the longitudinal currents appearing in the process of reconnection are directed to the Earth on the morning side and from Earth - on the evening side. The results presented suggest that magnetic reconnection can serve as a sourse of the Birkeland current loop of a substorm

  11. Alcohol use disorder and tuberculosis treatment: A longitudinal ...

    African Journals Online (AJOL)

    Objective: The relationship between tuberculosis (TB) treatment and alcohol use disorders over time is under-researched. The aim of this investigation was to study alcohol use and TB medication adherence and its predictors among TB patients over a period of 6 months. Methods: A longitudinal investigation was carried out ...

  12. Accelerated brain aging in schizophrenia : A longitudinal pattern recognition study

    NARCIS (Netherlands)

    Schnack, Hugo G.; Van Haren, Neeltje E M; Nieuwenhuis, Mireille; Pol, Hilleke E Hulshoff; Cahn, Wiepke; Kahn, René S.

    2016-01-01

    OBJECTIVE: Despite the multitude of longitudinal neuroimaging studies that have been published, a basic question on the progressive brain loss in schizophrenia remains unaddressed: Does it reflect accelerated aging of the brain, or is it caused by a fundamentally different process? The authors used

  13. Accelerated Brain Aging in Schizophrenia : A Longitudinal Pattern Recognition Study

    NARCIS (Netherlands)

    Schnack, Hugo G; van Haren, Neeltje E M; Nieuwenhuis, Mireille; Hulshoff Pol, Hilleke E; Cahn, Wiepke; Kahn, René S

    2016-01-01

    OBJECTIVE: Despite the multitude of longitudinal neuroimaging studies that have been published, a basic question on the progressive brain loss in schizophrenia remains unaddressed: Does it reflect accelerated aging of the brain, or is it caused by a fundamentally different process? The authors used

  14. An Evaluation of PET Based on Longitudinal Data.

    Science.gov (United States)

    Mandeville, Garrett K.

    Although teacher inservice programs based on Madeline Hunter's Program for Effective Teaching (PET) have become very popular in U.S. schools, there is little evidence that the Hunter model ultimately results in increased student achievement. This longitudinal study attempts to evaluate the effects of Hunter-based staff development programs on…

  15. Toward a Phenomenological-Longitudinal Model of Media Gratification Processes.

    Science.gov (United States)

    Kielwasser, Alfred P.; And Others

    While not dismissing the "uses and gratifications" approach to research, this paper attempts to increase the theoretical and practical utility of gratifications measures by approaching them through a more phenomenological and longitudinal tack. The paper suggests that any "gratification unit" is given a unique meaning by the…

  16. Achievement Emotions and Academic Performance: Longitudinal Models of Reciprocal Effects

    Science.gov (United States)

    Pekrun, Reinhard; Lichtenfeld, Stephanie; Marsh, Herbert W.; Murayama, Kou; Goetz, Thomas

    2017-01-01

    A reciprocal effects model linking emotion and achievement over time is proposed. The model was tested using five annual waves of the Project for the Analysis of Learning and Achievement in Mathematics (PALMA) longitudinal study, which investigated adolescents' development in mathematics (Grades 5-9; N = 3,425 German students; mean starting…

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

    Science.gov (United States)

    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…

  18. A Longitudinal Study Assessing the Microsoft Office Skills Course

    Science.gov (United States)

    Carpenter, Donald A.; McGinnis, Denise; Slauson, Gayla Jo; Snyder, Johnny

    2013-01-01

    This paper explains a four-year longitudinal study of the assessment process for a Microsoft Office skills course. It examines whether there is an increase in students' knowledge based on responses to pre- and post-surveys that asked students to evaluate how well they can do particular tasks. Classical classroom teaching methods were used in the…

  19. Longitudinal study of computerized cardiotocography in early fetal growth restriction

    NARCIS (Netherlands)

    Wolf, H.; Arabin, B.; Lees, Christoph C.; Oepkes, D.; Prefumo, Federico; Thilaganathan, B.; Todros, T.; Visser, G.H.A.; Bilardo, Caterina M.; Derks, J. B.; Diemert, A.; Duvekot, Johannes J.; Ferrazzi, E.; Frusca, T.; Hecher, K.; Marlow, N.; Martinelli, P.; Ostermayer, E.; Papageorghiou, Aris T.; Scheepers, Hubertina C. J.; Schlembach, D.; Schneider, K. T M; Valcamonico, A.; van Wassenaer-Leemhuis, A.; Ganzevoort, W.; Aktas, Ayse; Borgione, Silvia; Brezinka, Christoph; Calvert, Sandra; Chaoui, Rabih; Cornette, Jerome M J; Diehl, Thilo; van Eyck, Jim; Fratelli, Nicola; van Haastert, Inge Lot; Johnson, Samantha; Lobmaier, Silvia; Lopriore, Enrico; Mansi, Giuseppina; Missfelder-Lobos, Hannah; Martelli, Paola; Maso, Gianpaolo; Maurer-Fellbaum, Ute; Van Charante, Nico Mensing; De Tollenaer, Susanne Mulder; Moore, Tamanna; Napolitano, Raffaele; Oberto, Manuela; Ogge, Giovanna; van der Post, Joris Am; Preston, Lucy; Raimondi, Francesco; Reiss, Irwin K M; Rigano, Serena; Schuit, Ewoud; Skabar, Aldo; Spaanderman, Marc E.; Weisglas-Kuperus, Nynke; Zimmermann, Andrea

    2017-01-01

    Objectives: To explore whether, in early fetal growth restriction (FGR), the longitudinal pattern of fetal heart rate (FHR) short-term variation (STV) can be used to identify imminent fetal distress and whether abnormalities of FHR recordings are associated with 2-year infant outcome. Methods: The

  20. Sensitivity Analysis of Mixed Models for Incomplete Longitudinal Data

    Science.gov (United States)

    Xu, Shu; Blozis, Shelley A.

    2011-01-01

    Mixed models are used for the analysis of data measured over time to study population-level change and individual differences in change characteristics. Linear and nonlinear functions may be used to describe a longitudinal response, individuals need not be observed at the same time points, and missing data, assumed to be missing at random (MAR),…

  1. Revisiting the Dedifferentiation Hypothesis with Longitudinal Multi-Cohort Data

    Science.gov (United States)

    de Frias, Cindy M.; Lovden, Martin; Lindenberger, Ulman; Nilsson, Lars-Goran

    2007-01-01

    The present longitudinal multi-cohort study examines whether interindividual variability in cognitive performance and change increases in old age, and whether associations among developments of different cognitive functions increase with adult age. Multivariate multiple-group latent growth modeling was applied to data from narrow cohorts separated…

  2. Longitudinal Modeling of Adolescent Normative Beliefs and Substance Initiation

    Science.gov (United States)

    Lillehoj, Catherine J.; Trudeau, Linda; Spoth, Richard

    2005-01-01

    Pstudy investigated the effects of baseline levels of academic achievement and longitudinal trends in normative beliefs on adolescent substance initiation across a 42-month time period. Participants were 272 rural adolescents who were an average of 12.3 years old at the baseline assessment. Academic achievement positively predicted the intercept…

  3. Longitudinal Factor Score Estimation Using the Kalman Filter.

    Science.gov (United States)

    Oud, Johan H.; And Others

    1990-01-01

    How longitudinal factor score estimation--the estimation of the evolution of factor scores for individual examinees over time--can profit from the Kalman filter technique is described. The Kalman estimates change more cautiously over time, have lower estimation error variances, and reproduce the LISREL program latent state correlations more…

  4. Transient heat transfer in longitudinal fins of various profiles with ...

    Indian Academy of Sciences (India)

    Transient heat transfer through a longitudinal fin of various profiles is studied. The thermal conductivity and heat transfer coefficients are assumed to be temperature dependent. The resulting partial differential equation is highly nonlinear. Classical Lie point symmetry methods are employed and some reductions are ...

  5. Intimate Partner Violence and Welfare Participation: A Longitudinal Causal Analysis

    Science.gov (United States)

    Cheng, Tyrone C.

    2013-01-01

    This longitudinal study examined the temporal-ordered causal relationship between intimate partner violence (IPV), five mental disorders (depression, generalized anxiety disorder, social phobia, panic attack, posttraumatic stress disorder [PTSD]), alcohol abuse/dependence, drug abuse/ dependence, treatment seeking (from physician, counselor, and…

  6. Thought Suppression and Meaning in Life: A Longitudinal Investigation

    Science.gov (United States)

    Krause, Neal

    2007-01-01

    The purpose of this study is to see if older adults who experience problems with thought suppression tend to encounter greater difficulty deriving a sense of meaning in life. Data from a longitudinal nationwide survey of older people (N = 988) indicate that greater difficulty with thought suppression is associated with a decline in meaning over…

  7. GWAS with longitudinal phenotypes : performance of approximate procedures

    NARCIS (Netherlands)

    Sikorska, Karolina; Mostafavi, Nahid; Uitterlinden, André; Rivadeneira, Fernando; Eilers, Paul HC; Lesaffre, Emmanuel

    2015-01-01

    Analysis of genome-wide association studies with longitudinal data using standard procedures, such as linear mixed model (LMM) fitting, leads to discouragingly long computation times. There is a need to speed up the computations significantly. In our previous work (Sikorska et al: Fast linear mixed

  8. GWAS with longitudinal phenotypes: Performance of approximate procedures

    NARCIS (Netherlands)

    K. Sikorska (Karolina); N.M. Montazeri (Nahid Mostafavi); A.G. Uitterlinden (André); F. Rivadeneira Ramirez (Fernando); P.H.C. Eilers (Paul); E.M.E.H. Lesaffre (Emmanuel)

    2015-01-01

    textabstractAnalysis of genome-wide association studies with longitudinal data using standard procedures, such as linear mixed model (LMM) fitting, leads to discouragingly long computation times. There is a need to speed up the computations significantly. In our previous work (Sikorska et al: Fast

  9. Measurement of flow fluctuations in single longitudinal mode pulsed ...

    Indian Academy of Sciences (India)

    2014-02-12

    Feb 12, 2014 ... Page 1 ... Keywords. Dye lasers; single longitudinal mode; flow fluctuations. PACS Nos 42.55.Mv; 42.60.Mi; 42.60.By. 1. Introduction. Narrow-band dye lasers offer ... stabilized tunable laser source plays an important role for many applications as mentioned above [1]. For tight wavelength control, the ...

  10. Longitudinal measurement of physical activity following kidney transplantation

    NARCIS (Netherlands)

    Dontje, M. L.; de Greef, Mathieu; Krijnen, W. P.; Corpeleijn, E.; Kok, T.; Bakker, S. J. L.; Stolk, R. P.; van der Schans, C. P.

    The purpose of this longitudinal observational study was to (i) examine the change of daily physical activity in 28 adult kidney transplant recipients over the first 12 months following transplantation; and (ii) to examine the change in metabolic characteristics and renal function.

  11. A Longitudinal Study of Gender-Related Cognition and Behaviour

    Science.gov (United States)

    Campbell, Anne; Shirley, Louisa; Candy, Julia

    2004-01-01

    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…

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

    Science.gov (United States)

    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…

  13. A Chinese Longitudinal Study on Work/Family Enrichment

    Science.gov (United States)

    Lu, Luo

    2011-01-01

    Purpose: The purpose of this paper is to explore reciprocal relationships between work/family resources, work/family enrichment (WFE), and work/family satisfaction in a Chinese society. Design/methodology/approach: A longitudinal design was adopted using a three-wave panel sample. Data were obtained from 310 Taiwanese employees on three occasions,…

  14. Time-dependent efficacy of longitudinal biomarker for clinical endpoint.

    Science.gov (United States)

    Kolamunnage-Dona, Ruwanthi; Williamson, Paula R

    2018-06-01

    Joint modelling of longitudinal biomarker and event-time processes has gained its popularity in recent years as they yield more accurate and precise estimates. Considering this modelling framework, a new methodology for evaluating the time-dependent efficacy of a longitudinal biomarker for clinical endpoint is proposed in this article. In particular, the proposed model assesses how well longitudinally repeated measurements of a biomarker over various time periods (0,t) distinguish between individuals who developed the disease by time t and individuals who remain disease-free beyond time t. The receiver operating characteristic curve is used to provide the corresponding efficacy summaries at various t based on the association between longitudinal biomarker trajectory and risk of clinical endpoint prior to each time point. The model also allows detecting the time period over which a biomarker should be monitored for its best discriminatory value. The proposed approach is evaluated through simulation and illustrated on the motivating dataset from a prospective observational study of biomarkers to diagnose the onset of sepsis.

  15. National Identity in EFL Learning: A Longitudinal Inquiry

    Science.gov (United States)

    Gu, Mingyue

    2010-01-01

    This article draws on a longitudinal study of four Chinese students' English learning experiences during their college years and explores the ways in which EFL learning has influenced their sense of national identity. The study captures the changes they have experienced in constructing identities over a prolonged period in the context of mainland…

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

    Science.gov (United States)

    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…

  17. 14 CFR 25.173 - Static longitudinal stability.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Static longitudinal stability. 25.173... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight Stability § 25.173 Static... forces (including friction) must be as follows: (a) A pull must be required to obtain and maintain speeds...

  18. LONGITUDINAL OSCILLATIONS IN DENSITY STRATIFIED AND EXPANDING SOLAR WAVEGUIDES

    Energy Technology Data Exchange (ETDEWEB)

    Luna-Cardozo, M. [Instituto de Astronomia y Fisica del Espacio, CONICET-UBA, CC. 67, Suc. 28, 1428 Buenos Aires (Argentina); Verth, G. [School of Computing, Engineering and Information Sciences, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom); Erdelyi, R., E-mail: mluna@iafe.uba.ar, E-mail: robertus@sheffield.ac.uk, E-mail: gary.verth@northumbria.ac.uk [Solar Physics and Space Plasma Research Centre (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2012-04-01

    Waves and oscillations can provide vital information about the internal structure of waveguides in which they propagate. Here, we analytically investigate the effects of density and magnetic stratification on linear longitudinal magnetohydrodynamic (MHD) waves. The focus of this paper is to study the eigenmodes of these oscillations. It is our specific aim to understand what happens to these MHD waves generated in flux tubes with non-constant (e.g., expanding or magnetic bottle) cross-sectional area and density variations. The governing equation of the longitudinal mode is derived and solved analytically and numerically. In particular, the limit of the thin flux tube approximation is examined. The general solution describing the slow longitudinal MHD waves in an expanding magnetic flux tube with constant density is found. Longitudinal MHD waves in density stratified loops with constant magnetic field are also analyzed. From analytical solutions, the frequency ratio of the first overtone and fundamental mode is investigated in stratified waveguides. For small expansion, a linear dependence between the frequency ratio and the expansion factor is found. From numerical calculations it was found that the frequency ratio strongly depends on the density profile chosen and, in general, the numerical results are in agreement with the analytical results. The relevance of these results for solar magneto-seismology is discussed.

  19. Sex Differences in the Longitudinal Prediction of Adult Personality.

    Science.gov (United States)

    Sutton-Smith, B.; Rosenberg, B. G.

    This paper deals with two sets of data-one that fails to find any long-term sex differences in adults, and another which seems to find such differences. The Berkeley Guidance Study offers longitudinal data in which no variables differentiate between the two sexes at all age levels. From these results, the authors conclude that the normal course of…

  20. Longitudinal correlates of change in blood pressure in adolescent girls

    NARCIS (Netherlands)

    Daniels, [No Value; McMahon, RP; Obarzanek, E; Waclawiw, MA; Similo, SL; Biro, FM; Schreiber, GB; Kimm, SYS; Morrison, JA; Barton, BA

    The objective of this study was to assess the longitudinal changes in blood pressure in black and white adolescent girls and evaluate potential determinants of changes in blood pressure, including sexual maturation and body size. A total of 1213 black and 1166 white girls, ages 9 or 10 years at

  1. Using Longitudinal Scales Assessment for Instrumental Music Students

    Science.gov (United States)

    Simon, Samuel H.

    2014-01-01

    In music education, current assessment trends emphasize student reflection, tracking progress over time, and formative as well as summative measures. This view of assessment requires instrumental music educators to modernize their approaches without interfering with methods that have proven to be successful. To this end, the Longitudinal Scales…

  2. A Longitudinal Study of Accounting Students' Ethical Judgement Making Ability

    Science.gov (United States)

    Mohamed Saat, Maisarah; Porter, Stacey; Woodbine, Gordon

    2012-01-01

    This paper reports the effect of a moral education programme on the ethical judgement making ability of university students. The programme comprises two forms of intervention: a dedicated ethics course and subsequent practical training. A total of 113 accounting students from six Malaysian universities participated in a longitudinal study…

  3. Within-subject template estimation for unbiased longitudinal image analysis.

    Science.gov (United States)

    Reuter, Martin; Schmansky, Nicholas J; Rosas, H Diana; Fischl, Bruce

    2012-07-16

    Longitudinal image analysis has become increasingly important in clinical studies of normal aging and neurodegenerative disorders. Furthermore, there is a growing appreciation of the potential utility of longitudinally acquired structural images and reliable image processing to evaluate disease modifying therapies. Challenges have been related to the variability that is inherent in the available cross-sectional processing tools, to the introduction of bias in longitudinal processing and to potential over-regularization. In this paper we introduce a novel longitudinal image processing framework, based on unbiased, robust, within-subject template creation, for automatic surface reconstruction and segmentation of brain MRI of arbitrarily many time points. We demonstrate that it is essential to treat all input images exactly the same as removing only interpolation asymmetries is not sufficient to remove processing bias. We successfully reduce variability and avoid over-regularization by initializing the processing in each time point with common information from the subject template. The presented results show a significant increase in precision and discrimination power while preserving the ability to detect large anatomical deviations; as such they hold great potential in clinical applications, e.g. allowing for smaller sample sizes or shorter trials to establish disease specific biomarkers or to quantify drug effects. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Experimental study of the longitudinal instability for beam transport

    International Nuclear Information System (INIS)

    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

  5. Procedural justice and prisoners’ mental health problems: A longitudinal study

    NARCIS (Netherlands)

    Beijersbergen, K.A.; Dirkzwager, A.J.E.; Eichelsheim, V.I.; van der Laan, P.H.; Nieuwbeerta, P.

    2013-01-01

    Background Given the high prevalence of mental health problems among prisoners, knowledge on its determinants is important. Prior cross-sectional studies suggest that procedurally just treatment within prison is a significant predictor; however, longitudinal research is lacking. Aim The aims of this

  6. Monitoring of fetuses with intrauterine growth restriction: a longitudinal study

    NARCIS (Netherlands)

    Hecher, K.; Bilardo, C. M.; Stigter, R. H.; Ville, Y.; Hackelöer, B. J.; Kok, H. J.; Senat, M. V.; Visser, G. H.

    2001-01-01

    To describe the time sequence of changes in fetal monitoring variables in intrauterine growth restriction and to correlate these findings with fetal outcome at delivery. This was a prospective longitudinal observational multicenter study on 110 singleton pregnancies with growth-restricted fetuses

  7. Longitudinal Bidirectional Relations between Adolescents' Sympathy and Prosocial Behavior

    Science.gov (United States)

    Carlo, Gustavo; Padilla-Walker, Laura M.; Nielson, Matthew G.

    2015-01-01

    Despite the importance of understanding sympathy and prosocial behaviors, research on the development of these tendencies in adolescence remains relatively sparse. In the present study, we examined age trends and bidirectional longitudinal relations in sympathy and prosocial behaviors across early to middle adolescents. Participants were 500…

  8. A Longitudinal Study of School Districts' Sustained Improvement

    Science.gov (United States)

    Sampson, Pauline M.

    2011-01-01

    In this longitudinal study of one region in the state of Texas, there was an examination of district leadership and the sustaining of high student achievement for their districts. The results of this study suggest that sustained improvement of student achievement is very difficult. The districts that had sustained improvement had stable district…

  9. Draws on a relativistic pinch with a longitudinal magnetic field

    International Nuclear Information System (INIS)

    Trubnikov, B.A.

    1991-01-01

    The problems of draws on a relativistic pinch with longitudinal magnetic field are discussed. The absence of collisions promoting the energy exchange between different degrees of particle freedom is assumed. The calculations are conducted using the ideal relativistic anisotropic magnetic hydrodynamics equations. The spectrum of particles accelerated in the draws, is determined

  10. Keeping secrets from parents: Longitudinal associations of secrecy in adolescence

    NARCIS (Netherlands)

    Frijns, T.; Finkenauer, C.; Vermulst, A.A.; Engels, R.C.M.E.

    2005-01-01

    A 2-wave survey study among 1173 10-14-year-olds tested the longitudinal contribution of secrecy from parents to psychosocial and behavioral problems in adolescence. Additionally, it investigated a hypothesized contribution of secrecy from parents to adolescent development by examining its relation

  11. Longitudinal Monitoring of Public Reactions to the U.S

    Science.gov (United States)

    J.D. Absher; A.G. Graefe; R.C. Burns

    2008-01-01

    Natural resource managers need to better understand the impact of fees on outdoor recreationists. The debate about recreation fees involves both operational issues such as revenue use and social issues such as justice and fairness. The recreation fee program of the US Forest Service is over ten years old and it is now possible to gauge some of the longitudinal effects...

  12. A prospective longitudinal study to estimate the prevalence of ...

    African Journals Online (AJOL)

    A prospective longitudinal study to estimate the prevalence of obesity in Egyptian children with nocturnal enuresis and the association between body mass index and ... Egyptian Journal of Medical Human Genetics ... Response to the treatment was evaluated statistically and correlated with body mass index percentile.

  13. Extensions in Joint Modeling of Survival and Longitudinal Outcomes

    NARCIS (Netherlands)

    M. Murawska (Magdalena)

    2014-01-01

    markdownabstract__abstract__ In many medical studies both longitudinal and event history data are collected for each patient. A well-known and broadly studied example is found in AIDS research, where CD4 cell counts taken at different time points are related to the time-to-death. Often such

  14. Longitudinal Analysis of Academic Burnout in Korean Middle School Students.

    Science.gov (United States)

    Kim, Boyoung; Lee, Minyoung; Kim, Keunhwa; Choi, Hyunju; Lee, Sang Min

    2015-10-01

    The purpose of the study was to investigate the longitudinal relationships between the initial values and slopes of three dimensions of burnout syndrome (i.e. emotional exhaustion, cynicism and academic inefficacy). The study utilized four-wave longitudinal data from a total of 367 (81.6% response rate) middle school students in South Korea. Comprising a 6-month interval survey, the first survey was conducted in June 2010, the second in December 2010, the third in June 2011 and the fourth in December 2011. All participants were 13-year-olds at the first and second surveys, and 14-year-olds at the third and fourth surveys. The Maslach Burnout Inventory-Student Survey was used for each survey to assess the level of academic burnout. The longitudinal data were analysed using latent growth modelling. The results of the study indicated that high initial values (intercept) for emotional exhaustion were associated with a higher rate of increase (slope) in cynicism and academic inefficacy. On the other hand, high initial values for cynicism and academic inefficacy were associated with a lower rate of increase in the other dimensions. This longitudinal study should promote understanding of burned-out students and contribute to the literature by informing the design of prevention programmes for academic burnout. Copyright © 2014 John Wiley & Sons, Ltd.

  15. Statistical analysis of longitudinal network data with changing composition

    NARCIS (Netherlands)

    Huisman, M; Snijders, TAB; Snijders, Tom A.B.

    2003-01-01

    Markov chains can be used for the modeling of complex longitudinal network data. One class of probability models to model the evolution of social networks are stochastic actor-oriented models for network change proposed by Snijders. These models are continuous-time Markov chain models that are

  16. Unemployment and psychological distress among graduates: A longitudinal study

    NARCIS (Netherlands)

    Schaufeli, Wilmar B.; Van Yperen, Nico W.

    1992-01-01

    A longitudinal study which addresses the relationship between unemployment and psychological distress in Dutch technical college graduates is presented. Two samples were studied: sample 1 (N = 635) consisted of students leaving technical college and sample 2 (N = 487) consisted of technical college

  17. Effects of Team and Organizational Commitment--A Longitudinal Study

    Science.gov (United States)

    Neininger, Alexandra; Lehmann-Willenbrock, Nale; Kauffeld, Simone; Henschel, Angela

    2010-01-01

    Retention management, i.e., keeping qualified employees, is a top priority for contemporary organizations. Commitment, and especially team commitment, can be the key to mastering this challenge. There is a lack of longitudinal research concerning the development and the direction of the effects of team commitment over time. In a longitudinal…

  18. Secondary Analysis of National Longitudinal Transition Study 2 Data

    Science.gov (United States)

    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…

  19. Domain structure in soft ferrites by the longitudinal Kerr effect

    International Nuclear Information System (INIS)

    Kaczmarek, R.; Dautain, M.; Barradi-Ismail, T.

    1992-01-01

    For the first time, the longitudinal Kerr effect has been used in order to observe magnetic domains and their development in power ferrites. Image subtraction and processing leads to a magnetic contrast being a quasi derivative of the domains. A kind of integration procedure applied to them permits a reconstruction of a local hysteresis which parameters closely approach the global hysteresis data. (orig.)

  20. A Longitudinal Investigation of Peer Sexual Harassment Victimization in Adolescence

    Science.gov (United States)

    Petersen, Jennifer L.; Hyde, Janet Shibley

    2009-01-01

    The current study describes longitudinal trends in sexual harassment by adolescent peers and highlights gender, pubertal status, attractiveness, and power as predictors of harassment victimization. At the end of 5th, 7th, and 9th grades, 242 adolescents completed questionnaires about sexual harassment victimization, pubertal status, and perceived…

  1. The Δ excitation in the nuclear-charge longitudinal response

    International Nuclear Information System (INIS)

    Amore, P.; Cenni, R.; Saracco, P.; Genoa Univ., Genoa

    1999-01-01

    The presence of a resonant structure corresponding to the Δ excitation in the longitudinal response to an e.m. probe is investigated. It is shown that many-body effects could significantly increase the relativistic contribution suggested by M. Ericson and coworkers

  2. Always connected: a longitudinal field study of mobile communication

    NARCIS (Netherlands)

    Peters, O.; Ben Allouch, Soumaya

    2005-01-01

    Twenty-five novice users of a new mobile communication device were closely tracked for a period of three months. The results of this longitudinal field study show that people’s motivations for using mobile communication technology are initially influenced more strongly by their perceptions about the

  3. Accounting for dropout reason in longitudinal studies with nonignorable dropout.

    Science.gov (United States)

    Moore, Camille M; MaWhinney, Samantha; Forster, Jeri E; Carlson, Nichole E; Allshouse, Amanda; Wang, Xinshuo; Routy, Jean-Pierre; Conway, Brian; Connick, Elizabeth

    2017-08-01

    Dropout is a common problem in longitudinal cohort studies and clinical trials, often raising concerns of nonignorable dropout. Selection, frailty, and mixture models have been proposed to account for potentially nonignorable missingness by relating the longitudinal outcome to time of dropout. In addition, many longitudinal studies encounter multiple types of missing data or reasons for dropout, such as loss to follow-up, disease progression, treatment modifications and death. When clinically distinct dropout reasons are present, it may be preferable to control for both dropout reason and time to gain additional clinical insights. This may be especially interesting when the dropout reason and dropout times differ by the primary exposure variable. We extend a semi-parametric varying-coefficient method for nonignorable dropout to accommodate dropout reason. We apply our method to untreated HIV-infected subjects recruited to the Acute Infection and Early Disease Research Program HIV cohort and compare longitudinal CD4 + T cell count in injection drug users to nonusers with two dropout reasons: anti-retroviral treatment initiation and loss to follow-up.

  4. Potential Reciprocal Relationship between Motivation and Achievement: A Longitudinal Study

    Science.gov (United States)

    Liu, Yuan; Hou, Shumeng

    2018-01-01

    Among the non-cognitive factors that influence academic achievement, intrinsic motivation has been found to be a potential reciprocal factor. The present study aims to determine the causal relationship between other types of motivation and academic achievement. For this purpose, a large-scale data survey, the National Education Longitudinal Study…

  5. Problem Behaviours, Traditional Bullying and Cyberbullying among Adolescents: Longitudinal Analyses

    Science.gov (United States)

    Lester, Leanne; Cross, Donna; Shaw, Therese

    2012-01-01

    Problem Behaviour Theory suggests that young people's problem behaviours tend to cluster. This study examined the relationship between traditional bullying, cyberbullying and engagement in problem behaviours using longitudinal data from approximately 1500 students. Levels of traditional victimisation and perpetration at the beginning of secondary…

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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…

  8. Longitudinal Associations among Child Maltreatment, Social Functioning, and Cortisol Regulation

    Science.gov (United States)

    Alink, Lenneke R. A.; Cicchetti, Dante; Kim, Jungmeen; Rogosch, Fred A.

    2012-01-01

    Child maltreatment increases the risk for impaired social functioning and cortisol regulation. However, the longitudinal interplay among these factors is still unclear. This study aimed to shed light on the effect of maltreatment on social functioning and cortisol regulation over time. The sample consisted of 236 children (mean age 7.64 years, SD…

  9. High Frequency Longitudinal Damped Vibrations of a Cylindrical Ultrasonic Transducer

    Directory of Open Access Journals (Sweden)

    Mihai Valentin Predoi

    2014-01-01

    Full Text Available Ultrasonic piezoelectric transducers used in classical nondestructive testing are producing in general longitudinal vibrations in the MHz range. A simple mechanical model of these transducers would be very useful for wave propagation numerical simulations, avoiding the existing complicated models in which the real components of the transducer are modeled by finite elements. The classical model for longitudinal vibrations is not adequate because the generated longitudinal wave is not dispersive, the velocity being the same at any frequency. We have adopted the Rayleigh-Bishop model, which avoids these limitations, even if it is not converging to the first but to the second exact longitudinal mode in an elastic rod, as obtained from the complicated Pochhammer-Chree equations. Since real transducers have significant vibrations damping, we have introduced a damping term in the Rayleigh-Bishop model, increasing the imaginary part and keeping almost identical real part of the wavenumber. Common transducers produce amplitude modulated signals, completely attenuated after several periods. This can be modeled by two close frequencies, producing a “beat” phenomenon, superposed on the high damping. For this reason, we introduce a two-rod Rayleigh-Bishop model with damping. Agreement with measured normal velocity on the transducer free surface is encouraging for continuation of the research.

  10. LOPUT Laser: A novel concept to realize single longitudinal mode ...

    Indian Academy of Sciences (India)

    2014-02-05

    Feb 5, 2014 ... Abstract. We propose a novel type of cavity design to generate single longitudinal mode laser known as LOPUT cavity. LOPUT cavity stands for linear orthogonally polarized modes resulting in unidirectional travelling wave cavity. The technique can be applied to both isotropic as well as anisotropic gain ...

  11. Longitudinal characterization of course types of functional limitations

    NARCIS (Netherlands)

    Deeg, D.J.H.

    2005-01-01

    Purpose: Longitudinal data have provided evidence on factors that increase the risk of incidence of functional limitations. However, little insight exists in course types of functional limitations other than simple incidence or recovery. Methods: This contribution examines the variety of course

  12. A Longitudinal Analysis of Television Advertising Effects on Adolescents.

    Science.gov (United States)

    Moore, Roy L.; Moschis, George P.

    A longitudinal study examined both the short term and the long term effects of television advertising on the development of adolescents' consumption-related orientations. Questionnaires were administered to 556 adolescents in a number of schools in a southern state; a second wave of questionnaires was administered to a subsample of 230 of these…

  13. Predictors of Adolescent Breakfast Consumption: Longitudinal Findings from Project EAT

    Science.gov (United States)

    Bruening, Meg; Larson, Nicole; Story, Mary; Neumark-Sztainer, Dianne; Hannan, Peter

    2011-01-01

    Objective: To identify predictors of breakfast consumption among adolescents. Methods: Five-year longitudinal study Project EAT (Eating Among Teens). Baseline surveys were completed in Minneapolis-St. Paul schools and by mail at follow-up by youth (n = 800) transitioning from middle to high school. Linear regression models examined associations…

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

    Science.gov (United States)

    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 analysis…

  15. Longitudinal stress fracture of the femur: A rare presentation

    International Nuclear Information System (INIS)

    Bilreiro, Carlos; Bahia, Carla; Castro, Miguel Oliveira e

    2016-01-01

    We present the case of an 80 year old woman with hip pain, caused by a longitudinal femoral insufficiency stress fracture, depicted with radiographs, CT and MR. This type of fracture is very rare, with only a few cases reported. We conducted a literature review and compared the findings with the present case

  16. Longitudinal analysis of HIV risk behaviour patterns and their ...

    African Journals Online (AJOL)

    The goal of this study was to identify various HIV risk behaviours among tuberculosis (TB) patients in a longitudinal study design in South Africa. In 42 public primary healthcare facilities in three districts in three provinces, adult new TB and TB retreatment patients with hazardous or harmful alcohol use were interviewed ...

  17. Physics and technology of tunable pulsed single longitudinal mode ...

    Indian Academy of Sciences (India)

    Design and technology demonstration of compact, narrow bandwidth, high repetition rate, tunable SLM dye lasers in two different configurations, namely Littrow and grazing incidence grating (GIG), were carried out in our lab at BARC, India. The single longitudinal mode (SLM) dye laser generates single-mode laser beams ...

  18. A longitudinal study of tooth erosion in adolescents.

    NARCIS (Netherlands)

    El Aidi, H.; Bronkhorst, E.M.; Truin, G.J.

    2008-01-01

    Incidence studies on tooth erosion among adolescents are scarce. This longitudinal study aimed at estimating the prevalence, incidence, progression, and distribution of erosion in young adolescents over a 1.5-year period. Erosion at baseline was present in 32.2% of the 622 children (mean age, 11.9

  19. Adolescent psychosocial development: A review of longitudinal models and research.

    Science.gov (United States)

    Meeus, Wim

    2016-12-01

    This review used 4 types of longitudinal models (descriptive models, prediction models, developmental sequence models and longitudinal mediation models) to identify regular patterns of psychosocial development in adolescence. Eight patterns of adolescent development were observed across countries: (1) adolescent maturation in multiple developmental domains; (2) heterogeneous continuity of personal relationships; (3) good goes together with good, and bad with bad, across time in adolescence; (4) parents transmit values and behaviors to their adolescent children over time; (5) adolescent psychopathology leads to erosion of personal relationships with parents and peers; (6) adolescent psychopathology prevents adolescent independence from parents; (7) parental interference in personal issues of adolescents has counterproductive effects over time; (8) mood variability and (social and personal) uncertainty are mechanisms that maintain psychopathology in adolescence. Principles of life span developmental psychology are used to discuss adolescent maturation, and a developmental contextual perspective is used to discuss links between the various developmental patterns. Strengths and limitations of the various longitudinal models, and links between longitudinal and experimental research are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  20. A Longitudinal Study on Learner Career Advancement in MOOCs

    Science.gov (United States)

    Wang, Yuan; Paquette, Luc; Baker, Ryan

    2014-01-01

    In this paper, we present progress towards a longitudinal study of the post-course career advancement of MOOC learners. We present initial results and analysis plans for how to link this to in-course behaviour, towards better understanding the goals of all MOOC learners.

  1. Longitudinal Variation of the Lunar Tide in the Equatorial Electrojet

    Science.gov (United States)

    Yamazaki, Yosuke; Stolle, Claudia; Matzka, Jürgen; Siddiqui, Tarique A.; Lühr, Hermann; Alken, Patrick

    2017-12-01

    The atmospheric lunar tide is one known source of ionospheric variability. The subject received renewed attention as recent studies found a link between stratospheric sudden warmings and amplified lunar tidal perturbations in the equatorial ionosphere. There is increasing evidence from ground observations that the lunar tidal influence on the ionosphere depends on longitude. We use magnetic field measurements from the CHAMP satellite during July 2000 to September 2010 and from the two Swarm satellites during November 2013 to February 2017 to determine, for the first time, the complete seasonal-longitudinal climatology of the semidiurnal lunar tidal variation in the equatorial electrojet intensity. Significant longitudinal variability is found in the amplitude of the lunar tidal variation, while the longitudinal variability in the phase is small. The amplitude peaks in the Peruvian sector (˜285°E) during the Northern Hemisphere winter and equinoxes, and in the Brazilian sector (˜325°E) during the Northern Hemisphere summer. There are also local amplitude maxima at ˜55°E and ˜120°E. The longitudinal variation is partly due to the modulation of ionospheric conductivities by the inhomogeneous geomagnetic field. Another possible cause of the longitudinal variability is neutral wind forcing by nonmigrating lunar tides. A tidal spectrum analysis of the semidiurnal lunar tidal variation in the equatorial electrojet reveals the dominance of the westward propagating mode with zonal wave number 2 (SW2), with secondary contributions by westward propagating modes with zonal wave numbers 3 (SW3) and 4 (SW4). Eastward propagating waves are largely absent from the tidal spectrum. Further study will be required for the relative importance of ionospheric conductivities and nonmigrating lunar tides.

  2. Ureter smooth muscle cell orientation in rat is predominantly longitudinal.

    Science.gov (United States)

    Spronck, Bart; Merken, Jort J; Reesink, Koen D; Kroon, Wilco; Delhaas, Tammo

    2014-01-01

    In ureter peristalsis, the orientation of the contracting smooth muscle cells is essential, yet current descriptions of orientation and composition of the smooth muscle layer in human as well as in rat ureter are inconsistent. The present study aims to improve quantification of smooth muscle orientation in rat ureters as a basis for mechanistic understanding of peristalsis. A crucial step in our approach is to use two-photon laser scanning microscopy and image analysis providing objective, quantitative data on smooth muscle cell orientation in intact ureters, avoiding the usual sectioning artifacts. In 36 rat ureter segments, originating from a proximal, middle or distal site and from a left or right ureter, we found close to the adventitia a well-defined longitudinal smooth muscle orientation. Towards the lamina propria, the orientation gradually became slightly more disperse, yet the main orientation remained longitudinal. We conclude that smooth muscle cell orientation in rat ureter is predominantly longitudinal, though the orientation gradually becomes more disperse towards the proprial side. These findings do not support identification of separate layers. The observed longitudinal orientation suggests that smooth muscle contraction would rather cause local shortening of the ureter, than cause luminal constriction. However, the net-like connective tissue of the ureter wall may translate local longitudinal shortening into co-local luminal constriction, facilitating peristalsis. Our quantitative, minimally invasive approach is a crucial step towards more mechanistic insight into ureter peristalsis, and may also be used to study smooth muscle cell orientation in other tube-like structures like gut and blood vessels.

  3. Sample size determination for mediation analysis of longitudinal data.

    Science.gov (United States)

    Pan, Haitao; Liu, Suyu; Miao, Danmin; Yuan, Ying

    2018-03-27

    Sample size planning for longitudinal data is crucial when designing mediation studies because sufficient statistical power is not only required in grant applications and peer-reviewed publications, but is essential to reliable research results. However, sample size determination is not straightforward for mediation analysis of longitudinal design. To facilitate planning the sample size for longitudinal mediation studies with a multilevel mediation model, this article provides the sample size required to achieve 80% power by simulations under various sizes of the mediation effect, within-subject correlations and numbers of repeated measures. The sample size calculation is based on three commonly used mediation tests: Sobel's method, distribution of product method and the bootstrap method. Among the three methods of testing the mediation effects, Sobel's method required the largest sample size to achieve 80% power. Bootstrapping and the distribution of the product method performed similarly and were more powerful than Sobel's method, as reflected by the relatively smaller sample sizes. For all three methods, the sample size required to achieve 80% power depended on the value of the ICC (i.e., within-subject correlation). A larger value of ICC typically required a larger sample size to achieve 80% power. Simulation results also illustrated the advantage of the longitudinal study design. The sample size tables for most encountered scenarios in practice have also been published for convenient use. Extensive simulations study showed that the distribution of the product method and bootstrapping method have superior performance to the Sobel's method, but the product method was recommended to use in practice in terms of less computation time load compared to the bootstrapping method. A R package has been developed for the product method of sample size determination in mediation longitudinal study design.

  4. Estimators for longitudinal latent exposure models: examining measurement model assumptions.

    Science.gov (United States)

    Sánchez, Brisa N; Kim, Sehee; Sammel, Mary D

    2017-06-15

    Latent variable (LV) models are increasingly being used in environmental epidemiology as a way to summarize multiple environmental exposures and thus minimize statistical concerns that arise in multiple regression. LV models may be especially useful when multivariate exposures are collected repeatedly over time. LV models can accommodate a variety of assumptions but, at the same time, present the user with many choices for model specification particularly in the case of exposure data collected repeatedly over time. For instance, the user could assume conditional independence of observed exposure biomarkers given the latent exposure and, in the case of longitudinal latent exposure variables, time invariance of the measurement model. Choosing which assumptions to relax is not always straightforward. We were motivated by a study of prenatal lead exposure and mental development, where assumptions of the measurement model for the time-changing longitudinal exposure have appreciable impact on (maximum-likelihood) inferences about the health effects of lead exposure. Although we were not particularly interested in characterizing the change of the LV itself, imposing a longitudinal LV structure on the repeated multivariate exposure measures could result in high efficiency gains for the exposure-disease association. We examine the biases of maximum likelihood estimators when assumptions about the measurement model for the longitudinal latent exposure variable are violated. We adapt existing instrumental variable estimators to the case of longitudinal exposures and propose them as an alternative to estimate the health effects of a time-changing latent predictor. We show that instrumental variable estimators remain unbiased for a wide range of data generating models and have advantages in terms of mean squared error. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  5. Ureter smooth muscle cell orientation in rat is predominantly longitudinal.

    Directory of Open Access Journals (Sweden)

    Bart Spronck

    Full Text Available In ureter peristalsis, the orientation of the contracting smooth muscle cells is essential, yet current descriptions of orientation and composition of the smooth muscle layer in human as well as in rat ureter are inconsistent. The present study aims to improve quantification of smooth muscle orientation in rat ureters as a basis for mechanistic understanding of peristalsis. A crucial step in our approach is to use two-photon laser scanning microscopy and image analysis providing objective, quantitative data on smooth muscle cell orientation in intact ureters, avoiding the usual sectioning artifacts. In 36 rat ureter segments, originating from a proximal, middle or distal site and from a left or right ureter, we found close to the adventitia a well-defined longitudinal smooth muscle orientation. Towards the lamina propria, the orientation gradually became slightly more disperse, yet the main orientation remained longitudinal. We conclude that smooth muscle cell orientation in rat ureter is predominantly longitudinal, though the orientation gradually becomes more disperse towards the proprial side. These findings do not support identification of separate layers. The observed longitudinal orientation suggests that smooth muscle contraction would rather cause local shortening of the ureter, than cause luminal constriction. However, the net-like connective tissue of the ureter wall may translate local longitudinal shortening into co-local luminal constriction, facilitating peristalsis. Our quantitative, minimally invasive approach is a crucial step towards more mechanistic insight into ureter peristalsis, and may also be used to study smooth muscle cell orientation in other tube-like structures like gut and blood vessels.

  6. Formation of longitudinal axon pathways in Caenorhabditis elegans.

    Science.gov (United States)

    Hutter, Harald

    2017-11-18

    The small number of neurons and the simple architecture of the Caenorhabditis elegans (C. elegans) nervous system enables researchers to study axonal pathfinding at the level of individually identified axons. Axons in C. elegans extend predominantly along one of the two major body axes, the anterior-posterior axis and the dorso-ventral axis. This review will focus on axon navigation along the anterior-posterior axis, leading to the establishment of the longitudinal axon tracts, with a focus on the largest longitudinal axon tract, the ventral nerve cord (VNC). In the VNC, axons grow out in a stereotypic order, with early outgrowing axons (pioneers) playing an important role in guiding later outgrowing (follower) axons. Genetic screens have identified a number of genes specifically affecting the formation of longitudinal axon tracts. These genes include secreted proteins, putative receptors and adhesion molecules, as well as intracellular proteins regulating the cell's response to guidance cues. In contrast to dorso-ventral navigation, no major general guidance cues required for the establishment of longitudinal pathways have been identified so far. The limited penetrance of defects found in many mutants affecting longitudinal navigation suggests that guidance cues act redundantly in this process. The majority of the axon guidance genes identified in C. elegans are evolutionary conserved, i.e. have homologs in other animals, including vertebrates. For a number of these genes, a role in axon guidance has not been described outside C. elegans. Taken together, studies in C. elegans contribute to a fundamental understanding of the molecular basis of axonal navigation that can be extended to other animals, including vertebrates and probably humans as well. Copyright © 2017. Published by Elsevier Ltd.

  7. Fingerprints of transverse and longitudinal coupling between induced open quantum dots in the longitudinal magnetoconductance through antidot lattices

    Science.gov (United States)

    Ujevic, Sebastian; Mendoza, Michel

    2010-07-01

    We propose numerical simulations of longitudinal magnetoconductance through a finite antidot lattice located inside an open quantum dot with a magnetic field applied perpendicular to the plane. The system is connected to reservoirs using quantum point contacts. We discuss the relationship between the longitudinal magnetoconductance and the generation of transversal couplings between the induced open quantum dots in the system. The system presents longitudinal magnetoconductance maps with crossovers (between transversal bands) and closings (longitudinal decoupling) of fundamental quantum states related to the open quantum dots induced by the antidot lattice. A relationship is observed between the distribution of antidots and the formed conductance bands, allowing a systematic follow up of the bands as a function of the applied magnetic field and quantum point-contact width. We observed a high conductance intensity [between n and (n+1) quantum of conductance, n=1,2,… ] in the regions of crossover and closing of states. This suggests transversal couplings between the induced open quantum dots of the system that can be modulated by varying both the antidots potential and the quantum point-contact width. A new continuous channel (not expected) is induced by the variation in the contact width and generate Fano resonances in the conductance. These resonances can be manipulated by the applied magnetic field.

  8. Physical activity and motor competence present a positive reciprocal longitudinal relationship across childhood and early adolescence

    DEFF Research Database (Denmark)

    Lima, Rodrigo A.; Pfeiffer, Karin; Larsen, Lisbeth R.

    2017-01-01

    Background: The current study evaluated the reciprocal longitudinal relationship between physical activity (PA) and motor competence (MC) and the potential mediation of cardiorespiratory endurance across 7 years. Methods: This was a 7-year longitudinal study, the Copenhagen School Child Intervent......Background: The current study evaluated the reciprocal longitudinal relationship between physical activity (PA) and motor competence (MC) and the potential mediation of cardiorespiratory endurance across 7 years. Methods: This was a 7-year longitudinal study, the Copenhagen School Child...

  9. The Latent Curve ARMA (P, Q) Panel Model: Longitudinal Data Analysis in Educational Research and Evaluation

    Science.gov (United States)

    Sivo, Stephen; Fan, Xitao

    2008-01-01

    Autocorrelated residuals in longitudinal data are widely reported as common to longitudinal data. Yet few, if any, researchers modeling growth processes evaluate a priori whether their data have this feature. Sivo, Fan, and Witta (2005) found that not modeling autocorrelated residuals present in longitudinal data severely biases latent curve…

  10. Estimates of post-acceleration longitudinal bunch compression

    International Nuclear Information System (INIS)

    Judd, D.L.

    1977-01-01

    A simple analytic method is developed, based on physical approximations, for treating transient implosive longitudinal compression of bunches of heavy ions in an accelerator system for ignition of inertial-confinement fusion pellet targets. Parametric dependences of attainable compressions and of beam path lengths and times during compression are indicated for ramped pulsed-gap lines, rf systems in storage and accumulator rings, and composite systems, including sections of free drift. It appears that for high-confidence pellets in a plant producing 1000 MW of electric power the needed pulse lengths cannot be obtained with rings alone unless an unreasonably large number of them are used, independent of choice of rf harmonic number. In contrast, pulsed-gap lines alone can meet this need. The effects of an initial inward compressive drift and of longitudinal emittance are included

  11. Laser wakefield excitation and measurement by femtosecond longitudinal interferometry

    International Nuclear Information System (INIS)

    Siders, C.W.; Le Blanc, S.P.; Fisher, D.; Tajima, T.; Downer, M.C.

    1996-04-01

    Plasma density oscillations (Langmuir waves) in the wake of an intense (I peak ∼ 3 x 10 17 W/cm 2 ) laser pulse (100 fs) are measured with ultrafast time resolution using a longitudinal interferometric technique. Phase shifts consistent with large amplitude (δn e /n e ∼ 1) density waves at the electron plasma frequency were observed in a fully tunnel-ionized He plasma, corresponding to longitudinal electric fields of ∼ 10 GV/m. Strong radial ponderomotive forces enhance the density oscillations. As this technique utilizes a necessary component of any laser-based plasma accelerator, it promises to be a powerful tool for on-line monitoring and control of future plasma-based particle accelerators

  12. Does string fragmentation reveal more than longitudinal phase space?

    International Nuclear Information System (INIS)

    Schulze, H.J.; Aichelin, J.

    1989-01-01

    The fragmentation of a color string into hadrons is assumed to be a sequence of binary decays governed by Fermi's golden rule. In each decay step a hadron is produced and a string with lower energy is left. Assuming that the transition matrix element depends on p/sub T/ only the decay is completely determined by the longitudinal phase space and one parameter, the 2 > of the produced hadrons. We find an almost complete agreement with the experimental momentum (longitudinal and transversal) and multiplicity distributions and the number of produced particles. The ''seagull'' shape of 2 >(x) turns out to be completely due to the sphericity analysis. This leaves little room for extracting information of QCD from single-particle-inclusive fragmentation data

  13. Microscopic theory of longitudinal sound velocity in charge ordered manganites

    International Nuclear Information System (INIS)

    Rout, G C; Panda, S

    2009-01-01

    A microscopic theory of longitudinal sound velocity in a manganite system is reported here. The manganite system is described by a model Hamiltonian consisting of charge density wave (CDW) interaction in the e g band, an exchange interaction between spins of the itinerant e g band electrons and the core t 2g electrons, and the Heisenberg interaction of the core level spins. The magnetization and the CDW order parameters are considered within mean-field approximations. The phonon Green's function was calculated by Zubarev's technique and hence the longitudinal velocity of sound was finally calculated for the manganite system. The results show that the elastic spring involved in the velocity of sound exhibits strong stiffening in the CDW phase with a decrease in temperature as observed in experiments.

  14. Microscopic theory of longitudinal sound velocity in charge ordered manganites

    Energy Technology Data Exchange (ETDEWEB)

    Rout, G C [Condensed Matter Physics Group, PG Department of Applied Physics and Ballistics, FM University, Balasore 756 019 (India); Panda, S, E-mail: gcr@iopb.res.i [Trident Academy of Technology, F2/A, Chandaka Industrial Estate, Bhubaneswar 751 024 (India)

    2009-10-14

    A microscopic theory of longitudinal sound velocity in a manganite system is reported here. The manganite system is described by a model Hamiltonian consisting of charge density wave (CDW) interaction in the e{sub g} band, an exchange interaction between spins of the itinerant e{sub g} band electrons and the core t{sub 2g} electrons, and the Heisenberg interaction of the core level spins. The magnetization and the CDW order parameters are considered within mean-field approximations. The phonon Green's function was calculated by Zubarev's technique and hence the longitudinal velocity of sound was finally calculated for the manganite system. The results show that the elastic spring involved in the velocity of sound exhibits strong stiffening in the CDW phase with a decrease in temperature as observed in experiments.

  15. On the simulation of the tokamak longitUdinal field

    International Nuclear Information System (INIS)

    Simakov, A.S.

    1978-01-01

    The problem of imitation of tokamak longitudinal field with a limited number of coils of a toroidal solenoid is considered in connection with construction of the bench-mark facility for the tokamak superconductive magnetic system. These coils should satisfactorily imitate the fields of the absent twenty three coils in the region of the twenty fourth. Fields and forces are calculated by the Tokat program. The analysis of the variants considered showed that with refuse from limitations on the cryostat sizes with acceptable accuracy the longitudinal field by means of 7-8 coils is possible. With the given sizes of the cryostat (d=4.1 m) it is hardly possible to obtain acceptable field imitation because of great current densities in the neighbouring coils. But on the bench of four coils one can obtain data, which, probably, will be useful during the evaluation of attaining the project parameters of the toroidal solenoid

  16. Elastic stability of biaxially loaded longitudinally stiffened composite structures.

    Science.gov (United States)

    Viswanathan, A. V.; Tamekuni, M.; Tripp, L. L.

    1973-01-01

    A linear analysis method is presented for the elastic stability of structures of uniform cross section, that may be idealized as an assemblage of laminated plate-strips, flat and curved, and beams. Each plate-strip and beam covers the entire length of the structure and is simply supported on the edges normal to the longitudinal axis. Arbitrary boundary conditions may be specified on any external longitudinal side of plate-strips. The structure or selected plate-strips may be loaded in any desired combination of inplane biaxial loads. The analysis simultaneously considers all modes of instability and is applicable for the buckling of laminated composite structures. Some numerical results are presented to indicate possible applications.

  17. Rare stress fracture: longitudinal fracture of the femur.

    Science.gov (United States)

    Pérez González, M; Velázquez Fragua, P; López Miralles, E; Abad Moretón, M M

    42-year-old man with pain in the posterolateral region of the right knee that began while he was running. Initially, it was diagnosed by magnetic resonance (MR) as a possible aggressive process (osteosarcoma or Ewing's sarcoma) but with computed tomography it was noted a cortical hypodense linear longitudinal image with a continuous, homogeneous and solid periosteal reaction without clear soft tissue mass that in this patient suggest a longitudinal distal femoral fatigue stress fracture. This type of fracture at this location is very rare. Stress fractures are entities that can be confused with an agressive process. MR iscurrently the most sensitive and specific imaging method for its diagnosis. Copyright © 2017 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

  18. Longitudinal profile monitors using Coherent Smith–Purcell radiation

    International Nuclear Information System (INIS)

    Andrews, H.L.; Bakkali Taheri, F.; Barros, J.; Bartolini, R.; Cassinari, L.; Clarke, C.; Le Corre, S.; Delerue, N.; Doucas, G.; Fuster-Martinez, N.; Konoplev, I.; Labat, M.; Perry, C.; Reichold, A.; Stevenson, S.; Vieille Grosjean, M.

    2014-01-01

    Coherent Smith–Purcell radiation has the potential of providing information on the longitudinal profile of an electron bunch. The E-203 experiment at the FACET User Facility measures bunch profiles from the SLAC linac in the hundreds of femtoseconds range and the SPESO collaboration at Synchrotron SOLEIL is planning to make an accurate 2D map of the Coherent Smith–Purcell Radiation emission. - Highlights: • Coherent Smith–Purcell radiation can be used to measure longitudinal profiles in the hundred femtoseconds range. • The current setup used by the E-203 collaboration require integration over several shots and gratings. • Reducing the integration over a single shot and a single grating still yields a meaning full result. • The SPESO experiment at SOLEIL will make a systematic study of Coherent Smith–Purcell radiation

  19. Transverse and longitudinal emittance measurements in the ELSA linac

    International Nuclear Information System (INIS)

    Loulergue, A.; Dowell, D.H.; Joly, S.; De Brion, J.P.; Haouat, G.; Schumann, F.

    1997-01-01

    The ELSA RF linac photoinjector has been designed to deliver high-brightness electron beams. The present paper deals with the transverse and longitudinal emittance measurements, at different locations along the ELSA beam line, and the analysis of their variations as a function of the photoinjector parameters : magnetic field generated by the anode focusing lens, bunch charge and pulse duration. While transverse emittance has been already studied in other similar installations, there has been little study of the electron beam longitudinal dynamics. Experimental results are presented and compared to simulation-code expectations. For 2.0 nC, 85 A electron bunches, a normalized rms emittance of 2 π mm mrad and a brightness of 4.5 x 10 13 A/(π m rad) 2 at the linac exit have been measured as well as less than 10 keV rms energy spread (or less than 0.1% at 16.5 MeV). (orig.)

  20. An overview of longitudinal data analysis methods for neurological research.

    Science.gov (United States)

    Locascio, Joseph J; Atri, Alireza

    2011-01-01

    The purpose of this article is to provide a concise, broad and readily accessible overview of longitudinal data analysis methods, aimed to be a practical guide for clinical investigators in neurology. In general, we advise that older, traditional methods, including (1) simple regression of the dependent variable on a time measure, (2) analyzing a single summary subject level number that indexes changes for each subject and (3) a general linear model approach with a fixed-subject effect, should be reserved for quick, simple or preliminary analyses. We advocate the general use of mixed-random and fixed-effect regression models for analyses of most longitudinal clinical studies. Under restrictive situations or to provide validation, we recommend: (1) repeated-measure analysis of covariance (ANCOVA), (2) ANCOVA for two time points, (3) generalized estimating equations and (4) latent growth curve/structural equation models.

  1. An Overview of Longitudinal Data Analysis Methods for Neurological Research

    Directory of Open Access Journals (Sweden)

    Joseph J. Locascio

    2011-10-01

    Full Text Available The purpose of this article is to provide a concise, broad and readily accessible overview of longitudinal data analysis methods, aimed to be a practical guide for clinical investigators in neurology. In general, we advise that older, traditional methods, including (1 simple regression of the dependent variable on a time measure, (2 analyzing a single summary subject level number that indexes changes for each subject and (3 a general linear model approach with a fixed-subject effect, should be reserved for quick, simple or preliminary analyses. We advocate the general use of mixed-random and fixed-effect regression models for analyses of most longitudinal clinical studies. Under restrictive situations or to provide validation, we recommend: (1 repeated-measure analysis of covariance (ANCOVA, (2 ANCOVA for two time points, (3 generalized estimating equations and (4 latent growth curve/structural equation models.

  2. Longitudinal Research in Social Science: Some Theoretical Challenges

    Directory of Open Access Journals (Sweden)

    Thomas K. Burch

    2001-12-01

    Full Text Available Every advance carries with it potential problems, and longitudinal analysis is no exception. This paper focuses on the problems related to the massive amounts of data generated by longitudinal surveys. It is argued that a proliferation of data may be to the good but it will not necessarily lead to better scientific knowledge. Most demographers think the logical positivist way that theory arises out of empirical generalisations, but massive empirical investigations have only led to disappointing theoretical outcomes in demography. This paper discusses one way out of this impasse - to adopt a different view of theory, a model-based view of science. Theoretical models based on empirical generalisation should become the main representational device in science.

  3. Antiferromagnetic Ising model with transverse and longitudinal field

    International Nuclear Information System (INIS)

    Kischinhevsky, M.

    1985-01-01

    We study the quantum hamiltonian version of the Ising Model in one spacial dimension under an external longitudinal (uniform) field at zero temperature. A phenomenological renormalization group procedure is used to obtain the phase diagram; the transverse and longitudinal zero field limits are studied and we verify the validity of universality at non zero transverse fields, where two-dimensional critical behaviour is obtained. To perform the numerical calculations we use the Lanczos scheme, which gives highly precise results with rather short processing times. We also analyse the possibility of using these techniques to extend the present work to the quantum hamiltonian version of the q-state Potts Model (q>2) in larger system. (author) [pt

  4. LONGITUDINAL MISMATCH IN SCL AS A SOURCE OF BEAM HALO.

    Energy Technology Data Exchange (ETDEWEB)

    RUGGIERO,A.G.

    2003-06-19

    An advantage of a proton Super-conducting Linac (SCL) is that RF cavities can be operated independently, allowing easier beam transport: and acceleration. But cavities are to be separated by drifts long enough to avoid they couple to each other. Moreover, cavities are placed in cryostats that include inactive insertions for cold-warm transitions; and interspersed are warm insertions for magnets and other devices. The SCL is then an alternating sequence of accelerating elements and drifts. No periodicity is present, and the longitudinal motion is not adiabatic. This has the consequence that the beam bunch ellipse will tumble, dilute and create a halo in the momentum plane because of inherent nonlinearities. When this is coupled to longitudinal space-charge forces, it may cause beam loss with latent activation of the accelerator components.

  5. Immigrants' language skills: the immigrant experience in a longitudinal survey

    OpenAIRE

    Barry CHISWICK; Yew LEE; Paul W. MILLER

    2003-01-01

    This paper is concerned with the determinants of English language proficiency among immigrants. It presents a model based on economic incentives, exposure, and efficiency in language acquisition, which it tests using the Longitudinal Survey of Immigrants to Australia. Probit and bivariate probit analyses are employed. The hypotheses are supported by the data. The bivariate probit analysis across waves indicates a "regression to the mean" in the unobserved components of English language profic...

  6. Substantia Nigra Free Water Increases Longitudinally in Parkinson Disease.

    Science.gov (United States)

    Guttuso, T; Bergsland, N; Hagemeier, J; Lichter, D G; Pasternak, O; Zivadinov, R

    2018-02-01

    Free water in the posterior substantia nigra obtained from a bi-tensor diffusion MR imaging model has been shown to significantly increase over 1- and 4-year periods in patients with early-stage idiopathic Parkinson disease compared with healthy controls, which suggests that posterior substantia nigra free water may be an idiopathic Parkinson disease progression biomarker. Due to the known temporal posterior-to-anterior substantia nigra degeneration in idiopathic Parkinson disease, we assessed longitudinal changes in free water in both the posterior and anterior substantia nigra in patients with later-stage idiopathic Parkinson disease and age-matched healthy controls for comparison. Nineteen subjects with idiopathic Parkinson disease and 19 age-matched healthy control subjects were assessed on the same 3T MR imaging scanner at baseline and after approximately 3 years. Baseline mean idiopathic Parkinson disease duration was 7.1 years. Both anterior and posterior substantia nigra free water showed significant intergroup differences at baseline ( P Parkinson disease versus healthy controls); however, only anterior substantia nigra free water showed significant longitudinal group × time interaction increases ( P = .021, idiopathic Parkinson disease versus healthy controls). There were no significant longitudinal group × time interaction differences found for conventional diffusion tensor imaging or free water-corrected DTI assessments in either the anterior or posterior substantia nigra. Results from this study provide further evidence supporting substantia nigra free water as a promising disease-progression biomarker in idiopathic Parkinson disease that may help to identify disease-modifying therapies if used in future clinical trials. Our novel finding of longitudinal increases in anterior but not posterior substantia nigra free water is potentially a result of the much longer disease duration of our cohort compared with previously studied cohorts and the known

  7. Longitudinal Associations Between Cyberbullying Involvement and Adolescent Mental Health.

    OpenAIRE

    Fahy, AE; Stansfeld, SA; Smuk, M; Smith, NR; Cummins, S; Clark, C

    2016-01-01

    : Cyberbullying differs from face-to-face bullying and may negatively influence adolescent mental health, but there is a lack of definitive research on this topic. This study examines longitudinal associations between cyberbullying involvement and adolescent mental health. : Participants were 2,480 teenagers taking part in the Olympic Regeneration in East London study. We collected information from participants when they were 12-13 years old and again 1 year later to examine links between inv...

  8. Predictors of workplace violence among ambulance personnel: a longitudinal study

    OpenAIRE

    van der Velden, Peter G.; Bosmans, Mark W.G.; van der Meulen, Erik

    2015-01-01

    Abstract Aim To examine predictors of repeated confrontations with workplace violence among ambulance personnel, the proportion of exposure to potentially traumatic events that are aggression-related and to what extent personnel was able to prevent escalations. Although previous research assessed the prevalences among this group, little is known about predictors, to what extent PTE’s are WPV-related and their abilities to prevent escalations. Design A longitudinal study with a 6 months’ time ...

  9. Investigation of longitudinal control system for a small hydrofoil boat

    Science.gov (United States)

    Phillips, W. H.; Shaughnessy, J. D.

    1976-01-01

    An analysis of a hydromechanical system for longitudinal control of a small hydrofoil boat is presented. The system incorporates height and acceleration sensors operating flaps on the foils through a mechanical linkage. Effects of some of the system parameters on the stability and response to waves are shown. The results indicate that the system is capable of providing adequate stability, but the response to stern waves at low frequencies is larger than desired.

  10. Multidimensionality of Longitudinal Data: Unlocking the Age-Happiness Puzzle

    OpenAIRE

    Ning Li

    2014-01-01

    In social and economic analysis of longitudinal data, the socio-economic variables that are statistically significant in pooled data regressions sometimes become insignificant after individual fixed effects are controlled for. This phenomenon has been observed in the analysis of the relationship between age and happiness. The discrepancy in results between regressions with and without controlling for individual fixed effects is sometimes known as a mystery in the research of age and happiness...

  11. PARAMETRIC ANALYSIS OF LONGITUDINAL STABILITY UNMANNED AERIAL VEHICLE

    Directory of Open Access Journals (Sweden)

    Ievgen Udartsev

    2013-10-01

    Full Text Available 1024x768 We consider the aerodynamic characteristics of unmanned aircraft container type, which were obtained in a wind tunnel and refined amended by soot blowing elements propeller system and the influence of the earth's surface. The estimation of longitudinal static stability and its dependence on altitude, damping, coordinates of center of gravity, shoulder horizontal tail, wings rejection of mechanization. The variation of these parameters enables to optimize balancing system with minimal losses. Normal 0 false false false

  12. Longitudinal relationships among posturography and gait measures in multiple sclerosis.

    Science.gov (United States)

    Fritz, Nora E; Newsome, Scott D; Eloyan, Ani; Marasigan, Rhul Evans R; Calabresi, Peter A; Zackowski, Kathleen M

    2015-05-19

    Gait and balance dysfunction frequently occurs early in the multiple sclerosis (MS) disease course. Hence, we sought to determine the longitudinal relationships among quantitative measures of gait and balance in individuals with MS. Fifty-seven ambulatory individuals with MS (28 relapsing-remitting, 29 progressive) were evaluated using posturography, quantitative sensorimotor and gait measures, and overall MS disability with the Expanded Disability Status Scale at each session. Our cohort's age was 45.8 ± 10.4 years (mean ± SD), follow-up time 32.8 ± 15.4 months, median Expanded Disability Status Scale score 3.5, and 56% were women. Poorer performance on balance measures was related to slower walking velocity. Two posturography measures, the anterior-posterior sway and sway during static eyes open, feet apart conditions, were significant contributors to walk velocity over time (approximate R(2) = 0.95), such that poorer performance on the posturography measures was related to slower walking velocity. Similarly, the anterior-posterior sway and sway during static eyes closed, feet together conditions were also significant contributors to the Timed 25-Foot Walk performance over time (approximate R(2) = 0.83). This longitudinal cohort study establishes a strong relationship between clinical gait measures and posturography. The data show that increases in static posturography and reductions in dynamic posturography are associated with a decline in walk velocity and Timed 25-Foot Walk performance over time. Furthermore, longitudinal balance measures predict future walking performance. Quantitative walking and balance measures are important additions to clinical testing to explore longitudinal change and understand fall risk in this progressive disease population. © 2015 American Academy of Neurology.

  13. Longitudinal capture in the radio-frequency-quadrupole structure

    International Nuclear Information System (INIS)

    Inagaki, S.

    1980-03-01

    The radio-frequency-quadrupole (RFQ) linac structure not only can attain easily transverse focusing in the low-beta region, but also can obtain very high capture efficiency because of its low beta-lambda and low-particle rigidity. An optimization study of the zero space-charge longitudinal capture in an RFQ linac that yields configurations with large capture efficiency is described

  14. On generalization of electric field strength in longitudinally blown arcs

    OpenAIRE

    Yas'ko, O.I.; Esipchuk, A.M.; Qing, Z.; Schram, D.C.; Fauchais, P.

    1997-01-01

    Generalization of av. elec. field strength for different discharge conditions in longitudinally blown arcs is considered. Exptl. data for distinctive devices and different gases were used for phys. modeling. Anal. showed that heat transfer processes are responsible for I-E characteristic formation. Turbulent heat transfer is the most effective for atm. pressure discharges while convection plays the main role in vacuum arcs. A generalized I-E characteristic was obtained. [on SciFinder (R)

  15. Theory of longitudinal plasma waves with allowance for ion mobility

    International Nuclear Information System (INIS)

    Kichigin, G.N.

    2003-01-01

    One studies propagation of stationary longitudinal plasma wave of high amplitude in collisionless cold plasma with regard to motion of electrons and ions in a wave. One derived dependences of amplitudes of electric field, potential, frequency and length of wave on the speed of wave propagation and on the parameter equal to the ration of ion mass to electron mass. Account of motion of ions in the wave with maximum possible amplitude resulted in nonmonotone dependence of frequency on wave speed [ru

  16. Weaving leadership longitudinally: a qualitative study on faculty development

    OpenAIRE

    Joyce, Pauline

    2015-01-01

    Purpose The purpose of this study was to explore if faculty who undertake teacher preparation, which has a leadership intervention across each module, are better prepared to take on educational leadership roles. Methods A cross sectional qualitative approach was used as part of a longitudinal evaluation of a program. The aim was to explore the perceptions of a purposive sample across three cohorts of students. Data was collected via semi-structured interviews and were analyzed by thema...

  17. An Overview of Longitudinal Data Analysis Methods for Neurological Research

    OpenAIRE

    Locascio, Joseph J.; Atri, Alireza

    2011-01-01

    The purpose of this article is to provide a concise, broad and readily accessible overview of longitudinal data analysis methods, aimed to be a practical guide for clinical investigators in neurology. In general, we advise that older, traditional methods, including (1) simple regression of the dependent variable on a time measure, (2) analyzing a single summary subject level number that indexes changes for each subject and (3) a general linear model approach with a fixed-subject effect, shoul...

  18. Longitudinal acoustic instabilities in slender solid propellant rockets : linear analysis

    OpenAIRE

    García Schafer, Juan Esteban; Liñán Martínez, Amable

    2001-01-01

    To describe the acoustic instabilities in the combustion chambers of laterally burning solid propellant rockets the interaction of the mean flow with the acoustic waves is analysed, using multiple scale techniques, for realistic cases in which the combustion chamber is slender and the nozzle area is small compared with the cross-sectional area of the chamber. Associated with the longitudinal acoustic oscillations we find vorticity and entropy waves, with a wavelength typically small compared ...

  19. Investigation of longitudinal dynamic in laser electron storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Karnaukhov, I.; Zelinsky, A. E-mail: zelinsky@kipt.kharkov.ua; Telegin, Yu

    2001-09-01

    Longitudinal dynamic of electron beam due to radiation damping and quantum fluctuations in the storage ring with a laser-electron interaction section (Compton scattering) is investigated. This investigation was carried out by numerical simulations using the Monte Carlo method. The dependence of the steady-state energy spread of electron beam due to the Compton back scattering of photons on the electron beam energy and photon flash density were obtained. Simulation findings are compared with the analytical estimations by Z. Huang.

  20. Investigation of longitudinal dynamic in laser electron storage ring

    CERN Document Server

    Karnaukhov, I; Telegin, Yu P

    2001-01-01

    Longitudinal dynamic of electron beam due to radiation damping and quantum fluctuations in the storage ring with a laser-electron interaction section (Compton scattering) is investigated. This investigation was carried out by numerical simulations using the Monte Carlo method. The dependence of the steady-state energy spread of electron beam due to the Compton back scattering of photons on the electron beam energy and photon flash density were obtained. Simulation findings are compared with the analytical estimations by Z. Huang.

  1. Longitudinal stability of the LHC beam in the SPS

    CERN Document Server

    Shaposhnikova, Elena

    2001-01-01

    Longitudinal beam stability is analysed for the LHC Beam in the SPS. The most critical area is shown to be the top energy. Analysis explains some results of measurements with the beam done d uring the MDs last year. The possibility of using this cycle for CNGS is considered as well. There, without special requirements on bunch parameters at extraction, the impedance limitations move to the lowest energy. An option with low transition energy is presented also.

  2. Ethical Code Effectiveness in Football Clubs: A Longitudinal Analysis

    OpenAIRE

    Constandt, Bram; De Waegeneer, Els; Willem, Annick

    2017-01-01

    As football (soccer) clubs are facing different ethical challenges, many clubs are turning to ethical codes to counteract unethical behaviour. However, both in- and outside the sport field, uncertainty remains about the effectiveness of these ethical codes. For the first time, a longitudinal study design was adopted to evaluate code effectiveness. Specifically, a sample of non-professional football clubs formed the subject of our inquiry. Ethical code effectiveness was...

  3. Longitudinal instabilities in circular accelerator and storage rings

    International Nuclear Information System (INIS)

    Pellegrini, C.

    1981-01-01

    The general problem of the longitudinal stability of bunched beams is reviewed. Although there is no general solution it is possible to identify regions in the frequency-risetime space where we can obtain approximate solutions. The collective oscillation frequency is written, and expressions for the effective coupling impedance are given for the high or low frequency and slow and fast blow-up regimes

  4. Longitudinal coupling impedance of a thick iris collimator

    International Nuclear Information System (INIS)

    Gluckstern, R.L.; Jiang, S.

    1992-01-01

    A previous calculation of the longitudinal coupling impedance of an iris in a beam pipe turned out not to be well convergent. In this work an alternate basis vector for the matrix equations is constructed, leading to convergent results. Numerical results are presented for the limit a/b → ∞, corresponding to a beam passing through a circular hole in a thick wall. 4 figs., 4 refs

  5. Longitudinal study on reciprocity between personality traits and parenting stress

    OpenAIRE

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

    2014-01-01

    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 analysis revealed that in case of both mothers and fathers, neuroticism at age 33 predicted high parenting stress, and extraversion at age 33 predicted low paren...

  6. Longitudinal tracking studies for a high intensity proton synchrotron

    International Nuclear Information System (INIS)

    Lessner, E.; Cho, Y.; Harkay, K.; Symon, K.

    1995-01-01

    Results from longitudinal tracking studies for a high intensity proton synchrotron designed for a 1-MW spallation source are presented. The machine delivers a proton beam of 0.5 mA time-averaged current at a repetition rate of 30 Hz. The accelerator is designed to have radiation levels that allow hands-on-maintenance. However, the high beam intensity causes strong space charge fields whose effects may lead to particle loss and longitudinal instabilities. The space charge fields modify the particle distribution, distort the stable bucket area and reduce the rf linear restoring force. Tracking simulations were conducted to analyze the space charge effects on the dynamics of the injection and acceleration processes and means to circumvent them. The tracking studies led to the establishment of the injected beam parameters and rf voltage program that minimized beam loss and longitudinal instabilities. Similar studies for a 10-GeV synchrotron that uses the 2-GeV synchrotron as its injector are also discussed

  7. Longitudinal Stretching for Maturation of Vascular Tissues Using Magnetic Forces

    Directory of Open Access Journals (Sweden)

    Timothy R. Olsen

    2016-11-01

    Full Text Available Cellular spheroids were studied to determine their use as “bioinks” in the biofabrication of tissue engineered constructs. Specifically, magnetic forces were used to mediate the cyclic longitudinal stretching of tissues composed of Janus magnetic cellular spheroids (JMCSs, as part of a post-processing method for enhancing the deposition and mechanical properties of an extracellular matrix (ECM. The purpose was to accelerate the conventional tissue maturation process via novel post-processing techniques that accelerate the functional, structural, and mechanical mimicking of native tissues. The results of a forty-day study of JMCSs indicated an expression of collagen I, collagen IV, elastin, and fibronectin, which are important vascular ECM proteins. Most notably, the subsequent exposure of fused tissue sheets composed of JMCSs to magnetic forces did not hinder the production of these key proteins. Quantitative results demonstrate that cyclic longitudinal stretching of the tissue sheets mediated by these magnetic forces increased the Young’s modulus and induced collagen fiber alignment over a seven day period, when compared to statically conditioned controls. Specifically, the elastin and collagen content of these dynamically-conditioned sheets were 35- and three-fold greater, respectively, at seven days compared to the statically-conditioned controls at three days. These findings indicate the potential of using magnetic forces in tissue maturation, specifically through the cyclic longitudinal stretching of tissues.

  8. Typology of alcohol users based on longitudinal patterns of drinking.

    Science.gov (United States)

    Harrington, Magdalena; Velicer, Wayne F; Ramsey, Susan

    2014-03-01

    Worldwide, alcohol is the most commonly used psychoactive substance. However, heterogeneity among alcohol users has been widely recognized. This paper presents a typology of alcohol users based on an implementation of idiographic methodology to examine longitudinal daily and cyclic (weekly) patterns of alcohol use at the individual level. A secondary data analysis was performed on the pre-intervention data from a large randomized control trial. A time series analysis was performed at the individual level, and a dynamic cluster analysis was employed to identify homogenous longitudinal patterns of drinking behavior at the group level. The analysis employed 180 daily observations of alcohol use in a sample of 177 alcohol users. The first order autocorrelations ranged from -.76 to .72, and seventh order autocorrelations ranged from -.27 to .79. Eight distinct profiles of alcohol users were identified, each characterized by a unique configuration of first and seventh autoregressive terms and longitudinal trajectories of alcohol use. External validity of the profiles confirmed the theoretical relevance of different patterns of alcohol use. Significant differences among the eight subtypes were found on gender, marital status, frequency of drug use, lifetime alcohol dependence, family history of alcohol use and the Short Index of Problems. Our findings demonstrate that individuals can have very different temporal patterns of drinking behavior. The daily and cyclic patterns of alcohol use may be important for designing tailored interventions for problem drinkers. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Linearization of the longitudinal phase space without higher harmonic field

    Directory of Open Access Journals (Sweden)

    Benno Zeitler

    2015-12-01

    Full Text Available Accelerator applications like free-electron lasers, time-resolved electron diffraction, and advanced accelerator concepts like plasma acceleration desire bunches of ever shorter longitudinal extent. However, apart from space charge repulsion, the internal bunch structure and its development along the beam line can limit the achievable compression due to nonlinear phase space correlations. In order to improve such a limited longitudinal focus, a correction by properly linearizing the phase space is required. At large scale facilities like Flash at Desy or the European Xfel, a higher harmonic cavity is installed for this purpose. In this paper, another method is described and evaluated: Expanding the beam after the electron source enables a higher order correction of the longitudinal focus by a subsequent accelerating cavity which is operated at the same frequency as the electron gun. The elaboration of this idea presented here is based on a ballistic bunching scheme, but can be extended to bunch compression based on magnetic chicanes. The core of this article is an analytic model describing this approach, which is verified by simulations, predicting possible bunch length below 1 fs at low bunch charge. Minimizing the energy spread down to σ_{E}/E<10^{-5} while keeping the bunch long is another interesting possibility, which finds applications, e.g., in time resolved transmission electron microscopy concepts.

  10. Longitudinal Psychosocial Adjustment of Women to Human Papillomavirus Infection.

    Science.gov (United States)

    Hsu, Yu-Yun; Wang, Wei-Ming; Fetzer, Susan Jane; Cheng, Ya-Min; Hsu, Keng-Fu

    2018-05-29

    The aim of this study was to examine the psychosocial adjustment trajectory, focusing on psychological distress, sexual relationships and health care information, as well as factors which have an impact on adjustment on receiving a positive diagnosis of human papillomavirus infection. Human papillomavirus is a common sexually transmitted infection in females. To date, knowledge of the longitudinal psychosocial response to the diagnosis of human papillomavirus is limited. A prospective longitudinal design was conducted with a convenience sample. Women aged 20-65 years old were followed at one, 6 and 12 months after a diagnosis of HPV. Participants completed measures of initial emotional distress and followed-up psychosocial adjustment. A mixed-effects model was applied to analyze the longitudinal changes in psychosocial adjustment. Seventy human papillomavirus positive women participated in the study with nearly 20% of the women reporting emotional distress during their first visit. Mixed-effects model analyses showed that a trajectory of psychosocial adjustment in health care orientation, sexual relationship and psychosocial distress occur from one to 6 months after HPV diagnosis. However, a declining trend from 6-12 months was significant in health care orientation. Initial emotional distress was associated with changes in psychological adjustment. Psychosocial adjustment to human papillomavirus was worse at one month compared with 6 and 12 months after diagnosis. Healthcare providers should offer health information and psychosocial support to women according to their disease progression. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  11. A rotary piezoelectric actuator using longitudinal and bending hybrid transducer

    Directory of Open Access Journals (Sweden)

    Yingxiang Liu

    2012-12-01

    Full Text Available A rotary piezoelectric actuator using bolt-clamped type transducer with double driving feet is proposed in this study. The first-order longitudinal and fourth-order bending vibration modes are superimposed in the actuator to produce elliptical movements on the driving tips. Longitudinal PZT and bending PZT are clamped between the exponential shape horns and the flange by bolts. The vibration shape changes of the actuator are presented to give a clear explanation of its working principle. Several structural parameters of the exponential shape horn are selected and adjusted to accomplish the tuning process of the longitudinal and bending resonance frequencies. The input impedance and vibration characteristics are calculated by using FEM method; the gained results verify the feasibility of the proposed actuator. After the fabrication of a prototype, its vibration characteristics are measured by using a scanning laser Doppler vibrometer; the tested results are in good agreement with the FEM calculated results. The mechanical output performance experiments state that the prototype achieves a maximum speed of 129 r/min and a maximum torque of 1.5 Nm.

  12. Longitudinal emittance blowup in the large hadron collider

    CERN Document Server

    Baudrenghien, P

    2013-01-01

    The Large Hadron Collider (LHC) relies on Landau damping for longitudinal stability. To avoid decreasing the stability margin at high energy, the longitudinal emittance must be continuously increased during the acceleration ramp. Longitudinal blowup provides the required emittance growth. The method was implemented through the summer of 2010. Band-limited RF phase-noise is injected in the main accelerating cavities during the whole ramp of about 11min. Synchrotron frequencies change along the energy ramp, but the digitally created noise tracks the frequency change. The position of the noise-band, relative to the nominal synchrotron frequency, and the bandwidth of the spectrum are set by pre-defined constants, making the diffusion stop at the edges of the demanded distribution. The noise amplitude is controlled by feedback using the measurement of the average bunch length. This algorithm reproducibly achieves the programmed bunch length of about 1.2ns, at flat top with low bunch-to-bunch scatter and provides a...

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

    Science.gov (United States)

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

    2015-01-01

    The purpose of this study was to explore family medicine residents' perceptions of a newly restructured integrated longitudinal curriculum. 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. 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. 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.

  14. Chemistry of groundwater discharge inferred from longitudinal river sampling

    Science.gov (United States)

    Batlle-Aguilar, J.; Harrington, G. A.; Leblanc, M.; Welch, C.; Cook, P. G.

    2014-02-01

    We present an approach for identifying groundwater discharge chemistry and quantifying spatially distributed groundwater discharge into rivers based on longitudinal synoptic sampling and flow gauging of a river. The method is demonstrated using a 450 km reach of a tropical river in Australia. Results obtained from sampling for environmental tracers, major ions, and selected trace element chemistry were used to calibrate a steady state one-dimensional advective transport model of tracer distribution along the river. The model closely reproduced river discharge and environmental tracer and chemistry composition along the study length. It provided a detailed longitudinal profile of groundwater inflow chemistry and discharge rates, revealing that regional fractured mudstones in the central part of the catchment contributed up to 40% of all groundwater discharge. Detailed analysis of model calibration errors and modeled/measured groundwater ion ratios elucidated that groundwater discharging in the top of the catchment is a mixture of local groundwater and bank storage return flow, making the method potentially useful to differentiate between local and regional sourced groundwater discharge. As the error in tracer concentration induced by a flow event applies equally to any conservative tracer, we show that major ion ratios can still be resolved with minimal error when river samples are collected during transient flow conditions. The ability of the method to infer groundwater inflow chemistry from longitudinal river sampling is particularly attractive in remote areas where access to groundwater is limited or not possible, and for identification of actual fluxes of salts and/or specific contaminant sources.

  15. Facebook: an effective tool for participant retention in longitudinal research.

    Science.gov (United States)

    Mychasiuk, R; Benzies, K

    2012-09-01

    Facebook is currently one of the world's most visited websites, and home to millions of users who access their accounts on a regular basis. Owing to the website's ease of accessibility and free service, demographic characteristics of users span all domains. As such, Facebook may be a valuable tool for locating and communicating with participants in longitudinal research studies. This article outlines the benefit gained in a longitudinal follow-up study, of an intervention programme for at-risk families, through the use of Facebook as a search engine. Using Facebook as a resource, we were able to locate 19 participants that were otherwise 'lost' to follow-up, decreasing attrition in our study by 16%. Additionally, analysis indicated that hard-to-reach participants located with Facebook differed significantly on measures of receptive language and self-esteem when compared to their easier-to-locate counterparts. These results suggest that Facebook is an effective means of improving participant retention in a longitudinal intervention study and may help improve study validity by reaching participants that contribute differing results. © 2011 Blackwell Publishing Ltd.

  16. Mini transverse versus longitudinal incision in carpal tunnel syndrome

    International Nuclear Information System (INIS)

    Korkmaz, M.; Cepoglu, M.C.

    2013-01-01

    Objective: To evaluate the effectiveness of mini-transverse compared with mini-longitudinal incision for carpal tunnel release (CTR) with reference to postoperative functional capacity, symptom severity and complication rate. Study Design: Analytical study. Place and Duration of Study: Cumhuriyet University Medical Faculty, Department of Orthopaedics, Tokat State Hospital, Department of Orthopaedics and Medical Park Tokat Hospital, Department of Neurosurgery, from January 2007 to January 2009. Methodology: This study included 93 hands of 79 patients with carpal tunnel syndrome (CTS), which were operated between 2007 and 2009. Patients were divided according to incision types into Group-1 (undergoing mini-longitudinal incision) and Group-2 (undergoing mini-transverse incision). Patients were evaluated initially and at 3 weeks after treatment according to symptom severity and functional status of Boston Questionnaire (BQ). Demographic and clinical data were analyzed and compared statistically between two groups. Results: Statistically significant differences were observed in BQ symptom and functional scores between the pre- and postoperative period (p < 0.0001). BQ symptom and functional scores at postoperative period were better in Group-1 than Group-2 (p = 0.044 and p = 0.023 respectively). The scar hypersensitivity (p = 0.258) and tenderness (p = 1.00) associated with the incision sites were not statistically different. Conclusion: Longitudinal incision is more effective on symptom and functional conditions than transverse incision. However, there was less scar formation with transverse incision. (author)

  17. Chiral current generation in QED by longitudinal photons

    Directory of Open Access Journals (Sweden)

    J.L. Acosta Avalo

    2016-08-01

    Full Text Available We report the generation of a pseudovector electric current having imbalanced chirality in an electron–positron strongly magnetized gas in QED. It propagates along the external applied magnetic field B as a chiral magnetic effect in QED. It is triggered by a perturbative electric field parallel to B, associated to a pseudovector longitudinal mode propagating along B. An electromagnetic chemical potential was introduced, but our results remain valid even when it vanishes. A nonzero fermion mass was assumed, which is usually considered vanishing in the literature. In the quantum field theory formalism at finite temperature and density, an anomaly relation for the axial current was found for a medium of massive fermions. It bears some analogy to the Adler–Bell–Jackiw anomaly. From the expression for the chiral current in terms of the photon self-energy tensor in a medium, it is obtained that electrons and positrons scattered by longitudinal photons (inside the light cone contribute to the chiral current, as well as the to pair creation due to longitudinal photons (out of light cone. In the static limit, an electric pseudovector current is obtained in the lowest Landau level.

  18. Chiral current generation in QED by longitudinal photons

    Energy Technology Data Exchange (ETDEWEB)

    Acosta Avalo, J.L., E-mail: jlacosta@instec.cu [Instituto Superior de Tecnologías y Ciencias Aplicadas (INSTEC), Ave Salvador Allende, No. 1110, Vedado, La Habana 10400 (Cuba); Pérez Rojas, H., E-mail: hugo@icimaf.cu [Instituto de Cibernética, Matemática y Física (ICIMAF), Calle E esq 15, No. 309, Vedado, La Habana 10400 (Cuba)

    2016-08-15

    We report the generation of a pseudovector electric current having imbalanced chirality in an electron–positron strongly magnetized gas in QED. It propagates along the external applied magnetic field B as a chiral magnetic effect in QED. It is triggered by a perturbative electric field parallel to B, associated to a pseudovector longitudinal mode propagating along B. An electromagnetic chemical potential was introduced, but our results remain valid even when it vanishes. A nonzero fermion mass was assumed, which is usually considered vanishing in the literature. In the quantum field theory formalism at finite temperature and density, an anomaly relation for the axial current was found for a medium of massive fermions. It bears some analogy to the Adler–Bell–Jackiw anomaly. From the expression for the chiral current in terms of the photon self-energy tensor in a medium, it is obtained that electrons and positrons scattered by longitudinal photons (inside the light cone) contribute to the chiral current, as well as the to pair creation due to longitudinal photons (out of light cone). In the static limit, an electric pseudovector current is obtained in the lowest Landau level.

  19. Longitudinal Profiles of Adaptive Behavior in Fragile X Syndrome

    Science.gov (United States)

    Quintin, Eve-Marie; Jo, Booil; Lightbody, Amy A.; Hazlett, Heather Cody; Piven, Joseph; Hall, Scott S.; Reiss, Allan L.

    2014-01-01

    OBJECTIVE: To examine longitudinally the adaptive behavior patterns in fragile X syndrome. METHOD: Caregivers of 275 children and adolescents with fragile X syndrome and 225 typically developing children and adolescents (2–18 years) were interviewed with the Vineland Adaptive Behavior Scales every 2 to 4 years as part of a prospective longitudinal study. RESULTS: Standard scores of adaptive behavior in people with fragile X syndrome are marked by a significant decline over time in all domains for males and in communication for females. Socialization skills are a relative strength as compared with the other domains for males with fragile X syndrome. Females with fragile X syndrome did not show a discernible pattern of developmental strengths and weaknesses. CONCLUSIONS: This is the first large-scale longitudinal study to show that the acquisition of adaptive behavior slows as individuals with fragile X syndrome age. It is imperative to ensure that assessments of adaptive behavior skills are part of intervention programs focusing on childhood and adolescence in this condition. PMID:25070318

  20. Longitudinal in vivo MR imaging of live earthworms.

    Science.gov (United States)

    Budán, Ferenc; Kovács, Noémi; Engelmann, Péter; Horváth, Ildikó; Veres, Dániel S; Németh, Péter; Szigeti, Krisztián; Máthé, Domokos

    2014-11-01

    Earthworm (Oligochaeta, Lumbricidae) species are used widely in eco-toxicological tests especially with contaminated soils. These long-term tests are reliable, but a high sample size is needed. Magnetic resonance imaging (MRI) can produce fast, robust, sensitive, and longitudinal morphological results using a small sample size. Performing longitudinal in vivo examinations of earthworms using MRI requires the need for anesthetics to completely avoid earthworm's moving. Our goal was to develop a simple and non-invasive method to anesthetize earthworms for in vivo longitudinal imaging studies. We investigated a number of different anesthesia methods and found that propan-2-ol and its vapor was optimal. We used a commercial sequential nanoScan® PET/MRI system (Mediso Ltd, Hungary, Budapest) to explore feasibility of MR imaging in immobilized earthworms. It was possible to visualize via micro MRI the brain, gastrointestinal tract, seminal vesicles, calciferous gland (Morren gland), and main blood vessels of the circulatory system. Our findings show the possibilities to examine changes in morphology using MRI of certain organs using a reversible, long-term immobilization method. © 2014 Wiley Periodicals, Inc.

  1. Longitudinal changes in cortical thickness in autism and typical development.

    Science.gov (United States)

    Zielinski, Brandon A; Prigge, Molly B D; Nielsen, Jared A; Froehlich, Alyson L; Abildskov, Tracy J; Anderson, Jeffrey S; Fletcher, P Thomas; Zygmunt, Kristen M; Travers, Brittany G; Lange, Nicholas; Alexander, Andrew L; Bigler, Erin D; Lainhart, Janet E

    2014-06-01

    The natural history of brain growth in autism spectrum disorders remains unclear. Cross-sectional studies have identified regional abnormalities in brain volume and cortical thickness in autism, although substantial discrepancies have been reported. Preliminary longitudinal studies using two time points and small samples have identified specific regional differences in cortical thickness in the disorder. To clarify age-related trajectories of cortical development, we examined longitudinal changes in cortical thickness within a large mixed cross-sectional and longitudinal sample of autistic subjects and age- and gender-matched typically developing controls. Three hundred and forty-five magnetic resonance imaging scans were examined from 97 males with autism (mean age = 16.8 years; range 3-36 years) and 60 males with typical development (mean age = 18 years; range 4-39 years), with an average interscan interval of 2.6 years. FreeSurfer image analysis software was used to parcellate the cortex into 34 regions of interest per hemisphere and to calculate mean cortical thickness for each region. Longitudinal linear mixed effects models were used to further characterize these findings and identify regions with between-group differences in longitudinal age-related trajectories. Using mean age at time of first scan as a reference (15 years), differences were observed in bilateral inferior frontal gyrus, pars opercularis and pars triangularis, right caudal middle frontal and left rostral middle frontal regions, and left frontal pole. However, group differences in cortical thickness varied by developmental stage, and were influenced by IQ. Differences in age-related trajectories emerged in bilateral parietal and occipital regions (postcentral gyrus, cuneus, lingual gyrus, pericalcarine cortex), left frontal regions (pars opercularis, rostral middle frontal and frontal pole), left supramarginal gyrus, and right transverse temporal gyrus, superior parietal lobule, and

  2. Comparing Longitudinal Profile Patterns of Mathematics and Reading in Early Child Longitudinal Study, Kindergarten: The Profile Analysis via Multidimensional Scaling (PAMS) Approach

    Science.gov (United States)

    Kim, Se-Kang

    2010-01-01

    The aim of the study is to compare longitudinal patterns from Mathematics and Reading data from the direct child assessment of Early Child Longitudinal Study, Kindergarten (ECLS-K, US Department of Education, National Center for Education Statistics 2006), utilizing Profile Analysis via Multidimensional Scaling (PAMS). PAMS has been used initially…

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

    Science.gov (United States)

    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),…

  4. Longitudinal variability of time-location/activity patterns of population at different ages: a longitudinal study in California

    Directory of Open Access Journals (Sweden)

    Cassady Diana L

    2011-09-01

    Full Text Available Abstract Background Longitudinal time-activity data are important for exposure modeling, since the extent to which short-term time-activity data represent long-term activity patterns is not well understood. This study was designed to evaluate longitudinal variations in human time-activity patterns. Method We report on 24-hour recall diaries and questionnaires collected via the internet from 151 parents of young children (mostly under age 55, and from 55 older adults of ages 55 and older, for both a weekday and a weekend day every three months over an 18-month period. Parents also provided data for their children. The self-administrated diary and questionnaire distinguished ~30 frequently visited microenvironments and ~20 activities which we selected to represent opportunities for exposure to toxic environmental compounds. Due to the non-normal distribution of time-location/activity data, we employed generalized linear mixed-distribution mixed-effect models to examine intra- and inter-individual variations. Here we describe variation in the likelihood of and time spent engaging in an activity or being in a microenvironment by age group, day-type (weekday/weekend, season (warm/cool, sex, employment status, and over the follow-up period. Results As expected, day-type and season influence time spent in many location and activity categories. Longitudinal changes were also observed, e.g., young children slept less with increasing follow-up, transit time increased, and time spent on working and shopping decreased during the study, possibly related to human physiological changes with age and changes in macro-economic factors such as gas prices and the economic recession. Conclusions This study provides valuable new information about time-activity assessed longitudinally in three major age groups and greatly expands our knowledge about intra- and inter-individual variations in time-location/activity patterns. Longitudinal variations beyond weekly and

  5. Parameter optimization method for longitudinal vibration absorber of ship shaft system

    Directory of Open Access Journals (Sweden)

    LIU Jinlin

    2017-05-01

    Full Text Available The longitudinal vibration of the ship shaft system is the one of the most important factors of hull stern vibration, and it can be effectively minimized by installing a longitudinal vibration absorber. In this way, the vibration and noise of ships can be brought under control. However, the parameters of longitudinal vibration absorbers have a great influence on the vibration characteristics of the shaft system. As such, a certain shafting testing platform was studied as the object on which a finite model was built, and the relationship between longitudinal stiffness and longitudinal vibration in the shaft system was analyzed in a straight alignment state. Furthermore, a longitudinal damping model of the shaft system was built in which the parameters of the vibration absorber were non-dimensionalized, the weight of the vibration absorber was set as a constant, and an optimizing algorithm was used to calculate the optimized stiffness and damping coefficient of the vibration absorber. Finally, the longitudinal vibration frequency response of the shafting testing platform before and after optimizing the parameters of the longitudinal vibration absorber were compared, and the results indicated that the longitudinal vibration of the shafting testing platform was decreased effectively, which suggests that it could provide a theoretical foundation for the parameter optimization of longitudinal vibration absorbers.

  6. Analysis on Longitudinal Dose according to Change of Field Width

    International Nuclear Information System (INIS)

    Jung, Won Seok; Shin, Ryung Mi; Oh, Byung Cheon; Jo, Jun Young; Kim, Gi Chul; Choi, Tae Gu; Back, Jong Geal

    2011-01-01

    To analyze the accuracy of tumor volume dose following field width change, to check the difference of dose change by using self-made moving car, and to evaluate practical delivery tumor dose when tomotherapy in the treatment of organ influenced by breathing. By using self-made moving car, the difference of longitudinal movement (0.0 cm, 1.0 cm, 1.5 cm, 2.0 cm) was applied and compared calculated dose with measured dose according to change of field width (1.05 cm, 2.50 cm, 5.02 cm) and apprehended margin of error. Then done comparative analysis in degree of photosensitivity of DQA film measured by using Gafchromic EBT film. Dose profile and Gamma histogram were used to measure degree of photosensitivity of DQA film. When field width were 1.05 cm, 2.50 cm, 5.02 cm, margin of error of dose delivery coefficient was -2.00%, -0.39%, -2.55%. In dose profile of Gafchromic EBT film's analysis, the movement of moving car had greater motion toward longitudinal direction and as field width was narrower, big error increased considerably at high dose part compared to calculated dose. The more field width was narrowed, gamma index had a large considerable influence of moving at gamma histogram. We could check the difference of longitudinal dose of moving organ. In order to small field width and minimize organ moving due to breathing, it is thought to be needed to develop breathing control unit and fixation tool.

  7. Bent versus straight tips in micropulsed longitudinal phacoemulsification.

    Science.gov (United States)

    Stagg, Brian C; Gupta, Isha; Cahoon, Judd; Ronquillo, Cecinio; Shi, Dallas; Zaugg, Brian; Gardiner, Gareth; Barlow, William R; Pettey, Jeff H; Aabid Farukhi, M; Jensen, Jason; Olson, Randall J

    2015-10-01

    The aim of this study was to evaluate bent and straight phacoemulsification tips to determine which tip is more efficient in removal of lens fragments, using micropulsed longitudinal ultrasound in phacoemulsification. In vitro laboratory study. The John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, was the study setting. Pig lenses hardened in a manner comparable with dense human cataracts were cut into 2-mm cubes and removed with micropulsed longitudinal ultrasound using settings previously shown to be optimally efficient (6 milliseconds on and 6 milliseconds off for a bent tip). To verify this time as most efficient for a straight tip, we also tested times of 5, 6, and 7 milliseconds time on and off. The tips were either straight or with a 20-degree bend. Twenty cubes were used for each comparative run. For the straight tip, 6 milliseconds on (1.56 ± 0.815 seconds) was significantly more efficient than 7 milliseconds on (2.45 ± 1.56 seconds, p = 0.001) and not significantly more efficient than 5 milliseconds on (1.69 ± 0.86 seconds, p = 0.43). Five milliseconds off time (1.45 ± 0.76s) was more efficient than 6 milliseconds (2.06 ± 1.37 seconds, p = 0.004) and 7 milliseconds off (2.18 ± 1.24s, p = 0.001). The straight tip was more efficient than the bent tip (1.38 ± 0.83 versus 2.93 ± 2.14 seconds, p = 0.006). Results are contrary to accepted common belief. Micropulsed longitudinal phacoemulsification is more efficient with a straight rather than a bent tip. Copyright © 2015 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  8. Longitudinal Modes along Thin Piezoelectric Waveguides for Liquid Sensing Applications

    Directory of Open Access Journals (Sweden)

    Cinzia Caliendo

    2015-06-01

    Full Text Available The propagation of longitudinally polarized acoustic modes along thin piezoelectric plates (BN, ZnO, InN, AlN and GaN is theoretically studied, aiming at the design of high frequency electroacoustic devices suitable for work in liquid environments. The investigation of the acoustic field profile across the plate revealed the presence of longitudinally polarized Lamb modes, travelling at velocities close to that of the longitudinal bulk acoustic wave propagating in the same direction. Such waves are suitable for the implementation of high-frequency, low-loss electroacoustic devices operating in liquid environments. The time-averaged power flow density, the phase velocity and the electroacoustic coupling coefficient K2 dispersion curves were studied, for the first (S0 and four higher order (S1, S2, S3, S4 symmetrical modes for different electrical boundary conditions. Two electroacoustic coupling configurations were investigated, based on interdigitated transducers, with or without a metal floating electrode at the opposite plate surface. Enhanced performances, such as a K2 as high as 8.5% and a phase velocity as high as 16,700 m/s, were demostrated for the ZnO- and BN-based waveguides, as an example. The relative velocity changes, and the inertial and viscous sensitivities of the first symmetric and anti-symmetric mode, S0 and A0, propagating along thin plates bordered by a viscous liquid were derived using the perturbation approach. The present study highlights the feasibility of the piezoelectric waveguides to the development of high-frequency, integrated-circuits compatible electroacoustic devices suitable for working in liquid environment.

  9. In vivo longitudinal chromatic aberration of pseudophakic eyes.

    Science.gov (United States)

    Siedlecki, Damian; Jóźwik, Agnieszka; Zając, Marek; Hill-Bator, Aneta; Turno-Kręcicka, Anna

    2014-02-01

    To present the results of longitudinal chromatic aberration measurements on two groups of pseudophakic eyes in comparison to healthy eyes. The longitudinal chromatic aberration of the eye, defined as chromatic difference of refraction with disabled accommodation, was measured with the use of a visual refractometer with a custom-designed target illuminator consisting of a narrow-band RGB diode (blue λb = 470 ± 15 nm; green λg = 525 ± 18 nm; red λr = 660 ± 10 nm). The measurements were performed on nine eyes implanted with AcrySof IQ SN60WF, 14 eyes implanted with AcrySof SA60AT, and 10 phakic eyes under cycloplegia. The mean values of the longitudinal chromatic aberration between 470 and 660 nm for the control group was 1.12 ± 0.14 D. For SA60AT group, it was 1.45 ± 0.42 D whereas for SN60WF it was 1.17 ± 0.52 D. The statistical test showed significant difference between SA60AT and the control group (p chromatic aberration in vivo can be easily and reliably estimated with an adapted visual refractometer. The two groups of pseudophakic eyes measured in this study showed different values of chromatic aberration. Its magnitude for SA60AT group was significantly larger than for the control group whereas for SN60WF the difference was not significant. The optical material used for intraocular lens design may have significant influence on the magnitude of the chromatic aberration of the pseudophakic eye, and therefore on its optical and visual performance in polychromatic light.

  10. Multilevel predictors of adolescent physical activity: a longitudinal analysis

    Directory of Open Access Journals (Sweden)

    Hearst Mary O

    2012-02-01

    Full Text Available Abstract Background To examine how factors from a social ecologic model predict physical activity (PA among adolescents using a longitudinal analysis. Methods Participants in this longitudinal study were adolescents (ages 10-16 at baseline and one parent enrolled in the Transdisciplinary Research on Energetics and Cancer-Identifying Determinants of Eating and Activity (TREC-IDEA and the Etiology of Childhood Obesity (ECHO. Both studies were designed to assess a socio-ecologic model of adolescent obesity risk. PA was collected using ActiGraph activity monitors at two time points 24 months apart. Other measures included objective height and weight, adolescent and parent questionnaires on multilevel psychological, behavioral and social determinants of PA, and a home PA equipment inventory. Analysis was conducted using SAS, including descriptive characteristics, bivariate and stepped multivariate mixed models, using baseline adjustment. Models were stratified by gender. Results There were 578 adolescents with complete data. Results suggest few statistically significant longitudinal associations with physical activity measured as minutes of MVPA or total counts from accelerometers. For boys, greater self-efficacy (B = 0.75, p = 0.01 and baseline MVPA (B = 0.55, p p = 0.01 and barriers (B = -0.32, p = 0.05 significantly predicted MVPA at follow-up in the full model. The full multilevel model explained 30% of the variance in PA among boys and 24% among girls. Conclusions PA change in adolescents is a complex issue that is not easily understood. Our findings suggest early PA habits are the most important predictor of PA levels in adolescence. Intervention may be necessary prior to middle school to maintain PA through adolescence.

  11. Causal mediation analysis for longitudinal data with exogenous exposure.

    Science.gov (United States)

    Bind, M-A C; Vanderweele, T J; Coull, B A; Schwartz, J D

    2016-01-01

    Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Longitudinal electron cooling experiments at HIRFL-CSRe

    International Nuclear Information System (INIS)

    Mao, L.J.; Zhao, H.; Yang, X.D.; Li, J.; Yang, J.C.; Yuan, Y.J.; Parkhomchuk, V.V.; Reva, V.B.; Ma, X.M.; Yan, T.L.; Tang, M.T.; Xia, J.W.

    2016-01-01

    At the heavy ion storage ring HIRFL-CSRe an electron cooler is operated to improve the beam conditions for experiments. The properties of cooled beams have been studied. The longitudinal beam dynamics during the cooling process was measured by a resonant Schottky detector. The dependencies of the parameters electron beam density and profile on cooling times were investigated. The friction force was measured directly with the aid of the high voltage system of the cooler and with the application of the beam bunching system as well. An experiment with bunched cold beam showed a dependence of the bunch length on the beam density.

  13. How do innovators stay innovative? A longitudinal case analysis

    OpenAIRE

    Tuzovic, Sven; Wirtz, Jochen; Heracleous, Loizos Th.

    2018-01-01

    Purpose – How can some companies be the innovation leader in their industry over prolonged periods of time, while others cannot? The purpose of this study is to understand a firm’s capability to be a successful serial innovator and to generate a constant stream of industry-leading innovations.\\ud \\ud Design/Methodology/Approach – The paper uses a longitudinal case study approach to gain an understanding of what and how Singapore Airlines (SIA) sustained service innovation for over 30 years. T...

  14. Wealth Distribution and Mobility in Denmark: a Longitudinal Study

    DEFF Research Database (Denmark)

    Bentzen, Jan Børsen; Schmidt-Sørensen, Jan Beyer

    1994-01-01

    We describe and analyse wealth mobility in a national sample of 32,675 individuals from the Danish Longitudinal Database over the period from 1983 to 1990. A transition matrix, the Shorrocks measure, average decile position for various subgroups, and wealth in 1990 compared with wealth in 1983...... are used to describe patterns of wealth mobility. These results and regression models of change in percentile position identify winners and losers. The losers include students, singles with children, those who changed residence and those who experienced unemployment, while the winners were the houseowners...

  15. Pediatric Acute Longitudinal Extensive Transverse Myelitis Secondary to Neuroborreliosis

    Directory of Open Access Journals (Sweden)

    Sana Khan

    2015-07-01

    Full Text Available Lyme neuroborreliosis has several different clinical manifestations in children, of which facial nerve palsies, meningitis and radiculopathies are the most common. Transverse myelitis (TM secondary to Lyme disease has been reported in rare occasions, typically presenting with severe weakness, sensory abnormalities and autonomic dysfunction. We present the case of a 16-year-old male who developed acute left peripheral facial palsy and longitudinal extensive TM secondary to Lyme disease. Remarkably, the patient reported only mild symptoms with severe back pain in the absence of profound signs of myelopathy. We reviewed the medical literature and analyzed the clinical features of pediatric patients with Borrelia burgdorferi-related TM.

  16. Self-stigma and suicidality: a longitudinal study.

    Science.gov (United States)

    Oexle, Nathalie; Rüsch, Nicolas; Viering, Sandra; Wyss, Christine; Seifritz, Erich; Xu, Ziyan; Kawohl, Wolfram

    2017-06-01

    Mental illness stigma is a source of distress for persons with mental illness. Self-stigma occurs when negative stereotypes are internalized, leading to low self-esteem, shame and hopelessness. Due to its consequences self-stigma may contribute to suicidality and be a modifiable target for suicide prevention. Based on 222 disability pensioners with mental illness we examined whether self-stigma at baseline is associated with suicidal ideation over a 2-year period, controlling for baseline suicidal ideation, symptoms, age and gender. More self-stigma predicted suicidal ideation at baseline and longitudinally. Interventions on different levels to reduce self-stigma could improve suicide prevention.

  17. Feedback stabilization system for pulsed single longitudinal mode tunable lasers

    Science.gov (United States)

    Esherick, Peter; Raymond, Thomas D.

    1991-10-01

    A feedback stabilization system for pulse single longitudinal mode tunable lasers having an excited laser medium contained within an adjustable length cavity and producing a laser beam through the use of an internal dispersive element, including detection of angular deviation in the output laser beam resulting from detuning between the cavity mode frequency and the passband of the internal dispersive element, and generating an error signal based thereon. The error signal can be integrated and amplified and then applied as a correcting signal to a piezoelectric transducer mounted on a mirror of the laser cavity for controlling the cavity length.

  18. The electrical conductivity and longitudinal magnetoresistance of metallic nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Moraga, Luis, E-mail: luismoragajaramillo@gmail.com [Universidad Central de Chile, Toesca 1783, Santiago 8370178 (Chile); Henriquez, Ricardo, E-mail: rahc.78@gmail.com [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Bravo, Sergio, E-mail: bravo.castillo.sergio@gmail.com [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Solis, Basilio, E-mail: bsolis1984@gmail.com [Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn (Germany)

    2017-03-01

    Proceeding from exact solutions of the Boltzmann transport equation in the relaxation time approximation, we present formulas for the electrical conductivity and longitudinal magnetoresistance of single-crystalline cylindrical nanotubes. The effects of surface scattering are taken into account by introducing different specularity parameters at the inner and outer surfaces. For small values of the inner diameter, these formulas reduce to the respective expressions for cylindrical nanowires. It is found that the existing measurements of the resistivity of nanotubes (Venkata Kamalakar and Raychaudhuri, New J. Phys. 14, 043032 (2012)) can be accurately described by this formalism.

  19. On the longitudinal coupling impedance of a toroidal beam tube

    International Nuclear Information System (INIS)

    Hahn, H.; Tepikian, S.

    1990-01-01

    In this paper, the longitudinal coupling impedance of a smooth toroidal beam tube is derived. By treating the torus as a slow-wave structure, the well-known method of describing the impedance in terms of cavity resonances can be used. A simple analytical expression for the coupling impedance of a toroidal beam tube with square cross section valid in the low-frequency limit is obtained. The results from the present study are compared with previously published solutions and qualitative differences are pointed out. 16 refs., 3 figs., 1 tab

  20. Influence of anisotropic hardening on longitudinal welding strains and stresses

    International Nuclear Information System (INIS)

    Gatovskij, K.M.; Revutskij, M.N.

    1981-01-01

    The algorithm and program for estimation of longitudinal welding strains and stresses with account of hardening and Bauschinger effect, which expand the possibilities of more complete description of stress change during thermodeformation welding cycles at bead surfacing on plate made of the 06Kh18N9T steel and AMg61 alloy. It is shown that for metals, deformation curves which are characterized by considerable yield moduli (Esub(T)/E>=0.05) hardening effect is considerable and its account leads to the decrease of stress level in the heataffected zone (down to 20%) [ru

  1. A Tool for Longitudinal Beam Dynamics in Synchrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Ostiguy, J.-F. [Fermilab; Lebedev, V. A. [Fermilab

    2017-05-01

    A number of codes are available to simulate longitudinal dynamics in synchrotrons. Some established ones include TIBETAN, LONG1D, ESME and ORBIT. While they embody a wealth of accumulated wisdom and experience, most of these codes were written decades ago and to some extent they reflect the constraints of their time. As a result, there is an interest for updated tools taking better advantage of modern software and hardware capabilities. At Fermilab, the PIP-II project has provided the impetus for development of such a tool. In this contribution, we discuss design decisions and code architecture. A selection of test cases based on an initial prototype are also presented.

  2. Total Longitudinal Moment Calculation and Reliability Analysis of Yacht Structures

    Science.gov (United States)

    Zhi, Wenzheng; Lin, Shaofen

    In order to check the reliability of the yacht in FRP (Fiber Reinforce Plastic) materials, in this paper, the vertical force and the calculation method of the overall longitudinal bending moment on yacht was analyzed. Specially, this paper focuses on the impact of speed on the still water bending moment on yacht. Then considering the mechanical properties of the cap type stiffeners in composite materials, the ultimate bearing capacity of the yacht has been worked out, finally the reliability of the yacht was calculated with using response surface methodology. The result can be used in yacht design and yacht driving.

  3. The optimization of longitudinal convective fins with internal heat generation

    International Nuclear Information System (INIS)

    Razelos, P.

    1979-01-01

    The solution of the optimization problem for longitudinal convective fins of constant thickness, triangular or parabolic profile, and uniform internal heat generation, is presented. The cases considered are those of a given heat generation density, total heat generation and heat generation per unit width of the fin, when either the heat dissipation or the width of the fin is prescribed. The results are set forth in a nondimensional form, which are presented graphically. The effect of the fin's thermal conductivity upon the optimum dimensions is discussed, and limiting values for the heat generation and the heat dissipation, which may be imposed on the fin for a feasible optimization, are also obtained. (Auth.)

  4. Runaway electron beam control for longitudinally pumped metal vapor lasers

    Science.gov (United States)

    Kolbychev, G. V.; Kolbycheva, P. D.

    1995-08-01

    Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

  5. Effective longitudinal strength of high temperature metal-matrix composites

    International Nuclear Information System (INIS)

    Craddock, J.N.; Savvides, I.

    1991-01-01

    Several models for predicting the longitudinal strength of fiber composites are presented, ranging from a simple netting analysis to a model incorporating curvilinear strain hardening for all the components. Results from these models are presented for tungsten fiber reinforced superalloys, FeCrAlY and MARM200. It is shown that a simple elastic limit micromechanical model does not always adequately describe the useful strength of the composites. The methods proposed here are shown to be more appropriate for predicting the effective composite strength. 2 refs

  6. Active Splitting in Longitudinal Power Systems based on a WAMPC

    Directory of Open Access Journals (Sweden)

    Felipe Arraño-Vargas

    2017-12-01

    Full Text Available This paper proposes an active splitting scheme especially suitable for longitudinal power systems (LPS. The proposed scheme is based on a modified out-of-step (OOS algorithm combined with an angle difference method using synchrophasor measurements. The remedial actions are based on the detection of possible loss of synchronism due to severe disturbances. The scheme was tested on a detailed dynamic model of the Central Interconnected System of Chile, a good example of extreme LPS. Obtained results show that remedial actions taken by the proposed protection scheme are able to avoid the total collapse of the system during critical contingencies.

  7. Longitudinal electron cooling experiments at HIRFL-CSRe

    Energy Technology Data Exchange (ETDEWEB)

    Mao, L.J., E-mail: maolijun@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhao, H. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yang, X.D.; Li, J.; Yang, J.C.; Yuan, Y.J. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Parkhomchuk, V.V.; Reva, V.B. [Budker Institute of Nuclear Physics, Novosibirsk 630090 (Russian Federation); Ma, X.M.; Yan, T.L. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Tang, M.T. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xia, J.W. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2016-02-01

    At the heavy ion storage ring HIRFL-CSRe an electron cooler is operated to improve the beam conditions for experiments. The properties of cooled beams have been studied. The longitudinal beam dynamics during the cooling process was measured by a resonant Schottky detector. The dependencies of the parameters electron beam density and profile on cooling times were investigated. The friction force was measured directly with the aid of the high voltage system of the cooler and with the application of the beam bunching system as well. An experiment with bunched cold beam showed a dependence of the bunch length on the beam density.

  8. Transverse-Longitudinal Coupling Effect in Laser Bunch Slicing

    International Nuclear Information System (INIS)

    Shimada, M.; Katoh, M.; Adachi, M.; Kimura, S.; Tanikawa, T.; Hosaka, M.; Yamamoto, N.; Takashima, Y.; Takahashi, T.

    2009-01-01

    We report turn-by-turn observation of coherent synchrotron radiation (CSR) produced by the laser bunch slicing technique at an electron storage ring operated with a small momentum compaction factor. CSR emission was intermittent, and its interval depended strongly on the betatron tune. This peculiar behavior of the CSR could be interpreted as a result of coupling between the transverse and longitudinal motion of the electrons. This is the first observation of such an effect, which would be important not only for controlling the CSR emission but also for generating and transporting ultrashort electron bunches or electron bunches with microdensity structures in advanced accelerators.

  9. Proximal alveolar bone loss in a longitudinal radiographic investigation

    International Nuclear Information System (INIS)

    Bolin, A.; Lavstedt, S.; Henrikson, C.O.; Frithiof, L.

    1986-01-01

    The difference in proximal alveolar bone height between 1970 and 1980, the ''ABD index'', has been measured longitudinally in radiographs from an unselected material. The group constitutes 406 individuals born in 1904 - 1952 in the county of Stockholm. 13 of 18 predictors determined in 1970 were significantly related to the ABD index in the simple correlation analyses. The predictor ''the alveolar bone loss 1970'' (ABL index 1970) had the strongest correlation to the ABD index. In the stepwise multiple regression analysis the predictor ABL index 1970 and three other predictors reached significant levels. These were age, number of lost teeth and Russell's Periodontal Index

  10. Giant transversal particle diffusion in a longitudinal magnetic ratchet.

    Science.gov (United States)

    Tierno, Pietro; Reimann, Peter; Johansen, Tom H; Sagués, Francesc

    2010-12-03

    We study the transversal motion of paramagnetic particles on a uniaxial garnet film, exhibiting a longitudinal ratchet effect in the presence of an oscillating magnetic field. Without the field, the thermal diffusion coefficient obtained by video microscopy is D(0) ≈ 3 × 10(-4)  μm2/s. With the field, the transversal diffusion exhibits a giant enhancement by almost four decades and a pronounced maximum as a function of the driving frequency. We explain the experimental findings with a theoretical interpretation in terms of random disorder effects within the magnetic film.

  11. Measured longitudinal beam impedance of booster gradient magnets; TOPICAL

    International Nuclear Information System (INIS)

    James L Crisp and Brian J. Fellenz

    2001-01-01

    The Booster gradient magnets have no vacuum pipe which forces the beam image current to flow along the laminated pole tips. Both D and F style magnets were measured with a stretched wire to determine the longitudinal beam impedance caused by these laminations. Results are compared to calculations done 30 years ago. The inductive part of the magnet impedance is interesting because it partially compensates for the negative inductance effects of space charge on the beam. An R/L circuit consisting of 37K(center d ot) in parallel with between 40 and 100uH is a reasonable approximation to the total impedance of Booster magnet laminations

  12. Children in care (CIC): A Danish longitudinal study

    DEFF Research Database (Denmark)

    Egelund, Tine; Hestbæk, Anne-Dorthe

    This paper presents results describing what characterizes young, Danish children in care and their parents, and, furthermore, discusses social policy implications of the complex psychosocial disadvantages influencing the families. The paper is based on a longitudinal study of all Danish children......, born in 1995, who currently are or formerly have been placed in care. The first data collection was conducted in the spring 2003, where the children were 7-8 years of age. It is the intention to follow up the children every third year during childhood, adolescence, and adult life. At each new data...

  13. Psychological predictors of eco-driving: A longitudinal study

    OpenAIRE

    Lauper Elisabeth; Moser Stephanie; Fischer Maja; Matthies Ellen; Kaufmann-Hayoz Ruth

    2015-01-01

    Eco-driving has well-known positive effects on fuel economy and greenhouse-gas emissions. Moreover, eco-driving reduces road-traffic noise, which is a serious threat to the health and well-being of many people. We investigated the psychological predictors of the adoption of eco-driving from the perspective of road-traffic noise abatement. The data came from 890 car drivers who participated in a longitudinal survey over four months. Specifically, we tested the effects of the intention to preve...

  14. POLARIZED BEAMS: 1 - Longitudinal electron spin polarization at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1994-09-15

    Wednesday 4 May marked a turning point in the art of the manipulation of spins in electron storage rings: longitudinal electron spin polarization (with the spins oriented along the electrons' direction of motion) was established in the electron ring of HERA, the electronproton collider at DESY in Hamburg. A polarization level of about 55% was obtained and polarizations of over 60% were reproducibly obtained in the following days. The beam energy was 27.52 GeV, corresponding to half integer spin tune of 62.5.

  15. A longitudinal evaluation of persons with disabilities: does a longitudinal definition help define who receives necessary care?

    Science.gov (United States)

    Chan, Leighton; Ciol, Marcia A; Shumway-Cook, Anne; Yorkston, Kathryn M; Dudgeon, Brian J; Asch, Steven M; Hoffman, Jeanne M

    2008-06-01

    To assess, using a longitudinal definition, the impact of disability on a broad range of objective health care quality indicators. Longitudinal cohort study following up with patients over several years. The first 2 interviews, 1 year apart, were used to determine each patient's disability status in activities of daily living (ADLs). Assessment of the health care indicators commenced after the second interview and continued throughout the survey period (an additional 1-3y). National survey. Participants (N=29,074) of the Medicare Current Beneficiary Survey (1992-2001) with no, increasing, decreasing, and stable ADL disability. Not applicable. The incidence of 5 avoidable outcomes, receipt of 3 preventive care measures, and adherence to 32 diagnostically based indicators assessing the quality of treatment for acute myocardial infarction [AMI], angina, breast cancer, cerebrovascular accident, transient ischemic attack, cholelithiasis, chronic obstructive pulmonary disease [COPD], congestive heart failure, depression, gastrointestinal bleeding, diabetes, and hypertension. For most indicators, less than 75% of eligible patients received necessary care, regardless of disability status. For 5 indicators, less than 50% of patients received appropriate treatment. In a logistic regression analysis that controlled for patient age, sex, race, and income, disability status was a significant factor in 7 quality measures (AMI, breast cancer, COPD, diabetes, angina, pneumonia, annual visits). Using a longitudinal definition of disability and objective health quality indicators, we found that disability status can be an important factor in determining receipt of quality health care in a broad range of diagnostic categories. However, the impact of disability status varies depending on the indicator measured. In this cohort of patients, the changing nature of a person's disability seems to have less impact than whether they ever have had any functional deficits.

  16. Stability of longitudinal oscillations of a bunch propagating through an evacuated chamber with reactive impedance

    International Nuclear Information System (INIS)

    Besnier, G.

    1979-01-01

    The longitudinal space-charge force is assumed to vary like the derivative of the longitudinal beam density. Solutions of the linearized Vlasov equation are then given as an expansion of normal modes for the longitudinal phase-space density of a bunched beam. For a given bunch intensity, the method allows calculation of the required synchrotron frequency spread inside a parabolic bunch, in order to stabilize the beam against coherent oscillations by Landau-damping. (Auth.)

  17. Generation of ten kilotesla longitudinal magnetic fields in ultraintense laser-solenoid target interactions

    OpenAIRE

    Xiao, K. D.; Zhou, C. T.; Zhang, H.; Huang, T. W.; Li, R.; Qiao, B.; Cao, J. M.; Cai, T. X.; Ruan, S. C.; He, X. T.

    2018-01-01

    Production of the huge longitudinal magnetic fields by using an ultraintense laser pulse irradiating a solenoid target is considered. Through three-dimensional particle-in-cell simulations, it is shown that the longitudinal magnetic field up to ten kilotesla can be observed in the ultraintense laser-solenoid target interactions. The finding is associated with both fast and return electron currents in the solenoid target. The huge longitudinal magnetic field is of interest for a number of impo...

  18. Deeply virtual Compton scattering off longitudinally polarised protons at HERMES

    International Nuclear Information System (INIS)

    Mahon, David Francis

    2010-03-01

    This thesis details the simultaneous extraction of three polarisation-dependent asymmetries in the distribution of real photons from the ep→epγ interaction and its indistinguishable deeply virtual Compton scattering and Bethe-Heitler processes at the HERMES fixed-target experiment at Desy. The data analysed were taken using a longitudinally polarised 27.57 GeV positron beam incident on a longitudinally polarised hydrogen gas target. The extracted asymmetries include two single-spin asymmetries A UL and A LU which depend on the polarisation of the target and beam respectively, averaged over all other polarisation states. The double-spin asymmetry A LL dependent on the product of the beam and target polarisations is extracted for the first time. The asymmetry amplitudes extracted relate to combinations of Generalised Parton Distributions (GPDs), predominantly H and H. The extracted amplitudes are presented across the HERMES kinematic range alongside theoretical predictions from a GPD model based on double distributions. Large sin φ and cos(0φ) amplitudes are observed for A UL and A LL respectively, with an unexpectedly large sin(2φ) amplitude for A UL . The results for the A UL and A LL asymmetries are broadly compatible with theory predictions, and the extracted A LU amplitudes are compatible with HERMES results extracted from a significantly larger data set. It is foreseen that these results will form input to future global data-based GPD models which aim to provide a better understanding of GPDs. (orig.)

  19. Latitudinal and longitudinal dispersion of energetic auroral protons

    Directory of Open Access Journals (Sweden)

    D. A. Lorentzen

    2000-01-01

    Full Text Available Using a collision by collision model from Lorentzen et al., the latitudinal and longitudinal dispersion of single auroral protons are calculated. The proton energies varies from 1 to 50 keV, and are released into the atmosphere at 700 km altitude. The dipole magnetic field has a dip-angle of 8 degrees. Results show that the main dispersion region is at high altitudes (300-350 km and occurs during the first few charge exchange collisions. As the proton travels further down the atmosphere the mean free path becomes smaller, and as a result the spreading effect will not be as pronounced. This means that the first few charge exchange collisions fully determines the width of both the latitudinal and longitudinal dispersion. The volume emission rate was calculated for energies between 1 and 50 keV, and it was found that dayside auroral hydrogen emissions rates were approximately 10 times weaker than nightside emission rates. Simulations were also performed to obtain the dependence of the particle dispersion as a function of initial pitch-angle. It was found that the dispersion varies greatly with initial pitch-angle, and the results are summarized in two tables; a main and an extreme dispersion region.Key words. Ionosphere (auroral ionosphere; · particle precipitation · Space plasma physics · (transport processes

  20. Longitudinal functional principal component modelling via Stochastic Approximation Monte Carlo

    KAUST Repository

    Martinez, Josue G.

    2010-06-01

    The authors consider the analysis of hierarchical longitudinal functional data based upon a functional principal components approach. In contrast to standard frequentist approaches to selecting the number of principal components, the authors do model averaging using a Bayesian formulation. A relatively straightforward reversible jump Markov Chain Monte Carlo formulation has poor mixing properties and in simulated data often becomes trapped at the wrong number of principal components. In order to overcome this, the authors show how to apply Stochastic Approximation Monte Carlo (SAMC) to this problem, a method that has the potential to explore the entire space and does not become trapped in local extrema. The combination of reversible jump methods and SAMC in hierarchical longitudinal functional data is simplified by a polar coordinate representation of the principal components. The approach is easy to implement and does well in simulated data in determining the distribution of the number of principal components, and in terms of its frequentist estimation properties. Empirical applications are also presented.

  1. SCI Longitudinal Aging Study: 40 Years of Research.

    Science.gov (United States)

    Krause, James S; Clark, Jillian M R; Saunders, Lee L

    2015-01-01

    The Spinal Cord Injury (SCI) Longitudinal Aging Study was initiated in 1973 and has conducted 8 assessments over the past 40 years. It was designed to help rehabilitation professionals understand the life situation of people with SCI, but it has developed into the most long-standing study of aging and SCI and has resulted in over 50 publications. Our purpose was to provide a detailed history of the study, response patterns, utilization of measures, and a summary of key findings reported in the literature. Five participant samples have been incorporated over the 40 years, with enrollment in 1973, 1984, 1993 (2 samples), and 2003. A total of 2,208 participants have completed 6,001 assessments, with a particularly large number of assessments among those who are more than 40 years post injury (n = 349). The overall results have indicated changing patterns of outcomes over time as persons with SCI age, with some notable declines in participation and health. There has been a survivor effect whereby persons who are more active, well-adjusted, and healthier live longer. This study has several important features that are required for longitudinal research including (a) consistency of follow-up, (b) consistency of measures over time, (c) addition of new participant samples to counteract attrition, and (d) inclusion of a large number of individuals who have reached aging milestones unparalleled in the literature. Data from this study can inform the literature on the natural course of aging with SCI.

  2. Small sample GEE estimation of regression parameters for longitudinal data.

    Science.gov (United States)

    Paul, Sudhir; Zhang, Xuemao

    2014-09-28

    Longitudinal (clustered) response data arise in many bio-statistical applications which, in general, cannot be assumed to be independent. Generalized estimating equation (GEE) is a widely used method to estimate marginal regression parameters for correlated responses. The advantage of the GEE is that the estimates of the regression parameters are asymptotically unbiased even if the correlation structure is misspecified, although their small sample properties are not known. In this paper, two bias adjusted GEE estimators of the regression parameters in longitudinal data are obtained when the number of subjects is small. One is based on a bias correction, and the other is based on a bias reduction. Simulations show that the performances of both the bias-corrected methods are similar in terms of bias, efficiency, coverage probability, average coverage length, impact of misspecification of correlation structure, and impact of cluster size on bias correction. Both these methods show superior properties over the GEE estimates for small samples. Further, analysis of data involving a small number of subjects also shows improvement in bias, MSE, standard error, and length of the confidence interval of the estimates by the two bias adjusted methods over the GEE estimates. For small to moderate sample sizes (N ≤50), either of the bias-corrected methods GEEBc and GEEBr can be used. However, the method GEEBc should be preferred over GEEBr, as the former is computationally easier. For large sample sizes, the GEE method can be used. Copyright © 2014 John Wiley & Sons, Ltd.

  3. Hydrodynamic role of longitudinal ridges in a leatherback turtle swimming

    Science.gov (United States)

    Bang, Kyeongtae; Kim, Jooha; Lee, Sang-Im; Choi, Haecheon

    2015-11-01

    The leatherback sea turtle (Dermochelys coriacea), the fastest swimmer and the deepest diver among marine turtles, has five longitudinal ridges on its carapace. These ridges are the most remarkable morphological features distinguished from other marine turtles. To investigate the hydrodynamic role of these ridges in the leatherback turtle swimming, we model a carapace with and without ridges by using three dimensional surface data of a stuffed leatherback turtle in the National Science Museum, Korea. The experiment is conducted in a wind tunnel in the ranges of the real leatherback turtle's Reynolds number (Re) and angle of attack (α). The longitudinal ridges function differently according to the flow condition (i.e. Re and α). At low Re and negative α that represent the swimming condition of hatchlings and juveniles, the ridges significantly decrease the drag by generating streamwise vortices and delaying the main separation. On the other hand, at high Re and positive α that represent the swimming condition of adults, the ridges suppress the laminar separation bubble near the front part by generating streamwise vortices and enhance the lift and lift-to-drag ratio. Supported by the NRF program (2011-0028032).

  4. Right-sizing statistical models for longitudinal data.

    Science.gov (United States)

    Wood, Phillip K; Steinley, Douglas; Jackson, Kristina M

    2015-12-01

    Arguments are proposed that researchers using longitudinal data should consider more and less complex statistical model alternatives to their initially chosen techniques in an effort to "right-size" the model to the data at hand. Such model comparisons may alert researchers who use poorly fitting, overly parsimonious models to more complex, better-fitting alternatives and, alternatively, may identify more parsimonious alternatives to overly complex (and perhaps empirically underidentified and/or less powerful) statistical models. A general framework is proposed for considering (often nested) relationships between a variety of psychometric and growth curve models. A 3-step approach is proposed in which models are evaluated based on the number and patterning of variance components prior to selection of better-fitting growth models that explain both mean and variation-covariation patterns. The orthogonal free curve slope intercept (FCSI) growth model is considered a general model that includes, as special cases, many models, including the factor mean (FM) model (McArdle & Epstein, 1987), McDonald's (1967) linearly constrained factor model, hierarchical linear models (HLMs), repeated-measures multivariate analysis of variance (MANOVA), and the linear slope intercept (linearSI) growth model. The FCSI model, in turn, is nested within the Tuckerized factor model. The approach is illustrated by comparing alternative models in a longitudinal study of children's vocabulary and by comparing several candidate parametric growth and chronometric models in a Monte Carlo study. (c) 2015 APA, all rights reserved).

  5. Longitudinal associations between parenting style and adolescent disordered eating behaviors.

    Science.gov (United States)

    Zubatsky, Max; Berge, Jerica; Neumark-Sztainer, Dianne

    2015-06-01

    The main purpose of this study was to identify the longitudinal association between specific parenting styles (authoritarian, authoritative, permissive, and neglectful) and adolescent disordered eating behaviors. The current study uses longitudinal data from a 5-year study to examine the associations between parenting style and disordered eating behaviors among adolescents. Data from adolescents (n = 2516) participating in Project EAT (Eating Among Teens), a population-based study from 31 Minnesota schools, were used in the analysis. Time 1 data were collected using in-class assessments of adolescents from Minneapolis/St. Paul schools, and Time 2 data were collected using mailed surveys 5 years later. General Linear Models were used to predict adolescent-reported disordered eating behaviors at Time 2 from adolescent-reported parenting style at Time 1. Adolescent boys and girls who had authoritarian mothers at Time 1 had a higher probability of extreme weight control behaviors 5 years later compared to adolescents with authoritative, permissive, or neglectful mothers. Adolescent girls with authoritarian mothers at Time 1 had a higher probability of engaging in binge-eating behaviors at Time 2 compared to adolescent girls with authoritative or permissive mothers. There were no significant associations between paternal parenting style and adolescent disordered eating behaviors. Although authoritarian parenting style served as a possible risk factor for disordered eating behaviors in adolescents, the findings were not conclusive. Future studies should investigate further the association between parenting style and weight control behaviors in adolescents.

  6. Dead or Alive? Dealing with Unknown Eligibility in Longitudinal Surveys

    Directory of Open Access Journals (Sweden)

    Watson Nicole

    2016-12-01

    Full Text Available Longitudinal surveys follow people over time and some of these people will die during the life of the panel. Through fieldwork effort, some deaths will be reported or known, but others will be unobserved due to sample members no longer being issued to field or having inconclusive fieldwork outcomes (such as a noncontact that is not followed by a contact at a later wave. The coverage of deaths identified among sample members has flow-on implications to nonresponse correction. Using the Household, Income and Labour Dynamics in Australia (HILDA Survey, four methods are used to examine the extent of missing death reports. The first method matches the sample to the national death register. The second method uses life-expectancy tables to extrapolate the expected number of deaths among the sample with unknown eligibility. The third method is similar but models deaths from data internal to the survey. The fourth method models deaths as part of the attrition process of a longitudinal survey. The last three methods are compared to the first method and the implications for the construction of balanced panel weights and subsequent population inference are explored.

  7. Mechanism for longitudinal growth of rod-shaped bacteria

    Science.gov (United States)

    Taneja, Swadhin; Levitan, Ben; Rutenberg, Andrew

    2013-03-01

    The peptidoglycan (PG) cell wall along with MreB proteins are major determinants of shape in rod-shaped bacteria. However the mechanism guiding the growth of this elastic network of cross-linked PG (sacculus) that maintains the integrity and shape of the rod-shaped cell remains elusive. We propose that the known anisotropic elasticity and anisotropic loading, due to the shape and turgor pressure, of the sacculus is sufficient to direct small gaps in the sacculus to elongate around the cell, and that subsequent repair leads to longitudinal growth without radial growth. We computationally show in our anisotropically stressed anisotropic elasticity model small gaps can extend stably in the circumferential direction for the known elasticity of the sacculus. We suggest that MreB patches that normally propagate circumferentially, are associated with these gaps and are steered with this common mechanism. This basic picture is unchanged in Gram positive and Gram negative bacteria. We also show that small changes of elastic properties can in fact lead to bi-stable propagation of gaps, both longitudinal and circumferential, that can explain the bi-stability in patch movement observed in ΔmblΔmreb mutants.

  8. Leadership in transformation: a longitudinal study in a nursing organization.

    Science.gov (United States)

    Viitala, Riitta

    2014-01-01

    Not only does leadership produce changes, but those changes produce leadership in organisations. The purpose of this paper is to present a theoretical and empirical analysis of the transformation of leadership at two different historical points in a health care organisation. It leans on the perspective of social constructionism, drawing especially from the ideas of Berger and Luckmann (1966). The paper seeks to improve understanding of how leaders themselves construct leadership in relation to organisational change. The empirical material was gathered in a longitudinal case study in a nursing organisation in two different historical and situational points. It consists of written narratives produced by nurse leaders that are analysed by applying discourse analysis. The empirical study revealed that the constructions of leadership were dramatically different at the two different historical and situational points. Leadership showed up as a complex, fragile and changing phenomenon, which fluctuates along with the other organisational changes. The results signal the importance of agency in leadership and the central role of "significant others". The paper questions the traditional categorisation and labelling of leadership as well as the cross-sectional studies in understanding leadership transformation. Its originality relates to the longitudinal perspective on transformation of leadership in the context of a health care organisation.

  9. On losses caused in RF cavities by longitudinal electric fields

    International Nuclear Information System (INIS)

    Halbritter, J.

    1976-02-01

    Rf modes with large longitudinal electric fields (div E vector unequal to 0) at the cavity wall systematically show worse rf properties than modes with div E vector identical with 0; e.g. enlarged rf residual losses. While magnetic residual losses R sub(res) proportional f 2 are due to uncharged inhomogeneities in the oxide coating the metal, the electric residual losses R sub(orthogonal) occur via charged states in the oxide: the recharging of those states by tunnel exchange causes excitation across the energy gap of the superconductor yielding residual losses at high rf field strengths. The interaction of E sub(orthogonal) with the charges generate (longitudinal) phonons showing up as contribution to R sub(orthogonal). The resulting R sub(orthogonal) increases with E sub(orthogonal) and is nearly independent of frequency f, indicating the importance of R sub(orthogonal) for low frequency sc cavities, especially at high field strengths. In addition R sub(orthogonal) can account for the observed large residual losses of strip line modes in narrow junctions and joints between superconductors. (orig.) [de

  10. Motor planning in children with cerebral palsy: A longitudinal perspective.

    Science.gov (United States)

    Lust, Jessica Mireille; Spruijt, Steffie; Wilson, Peter H; Steenbergen, Bert

    2018-08-01

    Motor planning is important for daily functioning. Deficits in motor planning can result in slow, inefficient, and clumsy motor behavior and are linked to disruptions in performance of activities of daily living in children with cerebral palsy (CP). However, the evidence in CP is primarily based on cross-sectional data. Data are presented on the development of motor planning in children with CP using a longitudinal design with three measurement occasions, each separated by 1 year. Twenty-two children with CP (9 boys, 13 girls; age in years;months, M = 7;1, SD = 1;2) and 22 age-matched controls (10 boys, 12 girls, M  = 7;1, SD = 1;3) participated. Children performed a bar transport task in which some conditions ("critical angles") required participants to sacrifice initial posture comfort in order to achieve end-state comfort. Performance on critical trials was analyzed using linear growth curve modeling. In general, children with CP showed poor end-state planning for critical angles. Importantly, unlike in controls, motor planning ability did not improve across the three measurement occasions in children with CP. These longitudinal results show that motor planning issues in CP do not resolve with development over childhood. Strategies to enhance motor planning are suggested for intervention.

  11. Boosting structured additive quantile regression for longitudinal childhood obesity data.

    Science.gov (United States)

    Fenske, Nora; Fahrmeir, Ludwig; Hothorn, Torsten; Rzehak, Peter; Höhle, Michael

    2013-07-25

    Childhood obesity and the investigation of its risk factors has become an important public health issue. Our work is based on and motivated by a German longitudinal study including 2,226 children with up to ten measurements on their body mass index (BMI) and risk factors from birth to the age of 10 years. We introduce boosting of structured additive quantile regression as a novel distribution-free approach for longitudinal quantile regression. The quantile-specific predictors of our model include conventional linear population effects, smooth nonlinear functional effects, varying-coefficient terms, and individual-specific effects, such as intercepts and slopes. Estimation is based on boosting, a computer intensive inference method for highly complex models. We propose a component-wise functional gradient descent boosting algorithm that allows for penalized estimation of the large variety of different effects, particularly leading to individual-specific effects shrunken toward zero. This concept allows us to flexibly estimate the nonlinear age curves of upper quantiles of the BMI distribution, both on population and on individual-specific level, adjusted for further risk factors and to detect age-varying effects of categorical risk factors. Our model approach can be regarded as the quantile regression analog of Gaussian additive mixed models (or structured additive mean regression models), and we compare both model classes with respect to our obesity data.

  12. The Longitudinal Effective CSR Force at Mild Compression

    International Nuclear Information System (INIS)

    Rui Li

    2005-01-01

    In the scheme of magnetic bunch compression, an electron bunch with linear energy chirp (energy-bunch length correlation), imposed by an upstream RF cavity, is sent to a magnetic chicane. The bunch length at the exit of the chicane can thus be manipulated via the pathlength-energy dependence due to chicane dispersion. As a linear energy-chirped bunch ((delta)-z correlation) being transported through a dispersive region (x-(delta) correlation), the bunch will have a linear horizontal-longitudinal (x-z) correlation in the configuration space (bunch tilt). Comparing to the case of a nontilted bunch, this x-z correlation modifies the geometry of particle interaction with respect to the direction of particle motion, which consequently modifies the retardation solution and the effective CSR forces. The simulation result of the CSR field for a tilted thin beam was presented earlier by Dohlus [1]. In this paper, we first give an example of the bunch x-z correlation, or bunch tilt, in a bunch compression chicane. The effect of this x-z correlation on the retardation solution and the longitudinal effective force are then analyzed for a line bunch with linear energy chirp transported by design optics

  13. Continuity and change in children's longitudinal neural responses to numbers.

    Science.gov (United States)

    Emerson, Robert W; Cantlon, Jessica F

    2015-03-01

    Human children possess the ability to approximate numerical quantity nonverbally from a young age. Over the course of early childhood, children develop increasingly precise representations of numerical values, including a symbolic number system that allows them to conceive of numerical information as Arabic numerals or number words. Functional brain imaging studies of adults report that activity in bilateral regions of the intraparietal sulcus (IPS) represents a key neural correlate of numerical cognition. Developmental neuroimaging studies indicate that the right IPS develops its number-related neural response profile more rapidly than the left IPS during early childhood. One prediction that can be derived from previous findings is that there is longitudinal continuity in the number-related neural responses of the right IPS over development while the development of the left IPS depends on the acquisition of numerical skills. We tested this hypothesis using fMRI in a longitudinal design with children ages 4 to 9. We found that neural responses in the right IPS are correlated over a 1-2-year period in young children whereas left IPS responses change systematically as a function of children's numerical discrimination acuity. The data are consistent with the hypothesis that functional properties of the right IPS in numerical processing are stable over early childhood whereas the functions of the left IPS are dynamically modulated by the development of numerical skills. © 2014 John Wiley & Sons Ltd.

  14. MR image analysis: Longitudinal cardiac motion influences left ventricular measurements

    International Nuclear Information System (INIS)

    Berkovic, Patrick; Hemmink, Maarten; Parizel, Paul M.; Vrints, Christiaan J.; Paelinck, Bernard P.

    2010-01-01

    Background: Software for the analysis of left ventricular (LV) volumes and mass using border detection in short-axis images only, is hampered by through-plane cardiac motion. Therefore we aimed to evaluate software that involves longitudinal cardiac motion. Methods: Twenty-three consecutive patients underwent 1.5-Tesla cine magnetic resonance (MR) imaging of the entire heart in the long-axis and short-axis orientation with breath-hold steady-state free precession imaging. Offline analysis was performed using software that uses short-axis images (Medis MASS) and software that includes two-chamber and four-chamber images to involve longitudinal LV expansion and shortening (CAAS-MRV). Intraobserver and interobserver reproducibility was assessed by using Bland-Altman analysis. Results: Compared with MASS software, CAAS-MRV resulted in significantly smaller end-diastolic (156 ± 48 ml versus 167 ± 52 ml, p = 0.001) and end-systolic LV volumes (79 ± 48 ml versus 94 ± 52 ml, p < 0.001). In addition, CAAS-MRV resulted in higher LV ejection fraction (52 ± 14% versus 46 ± 13%, p < 0.001) and calculated LV mass (154 ± 52 g versus 142 ± 52 g, p = 0.004). Intraobserver and interobserver limits of agreement were similar for both methods. Conclusion: MR analysis of LV volumes and mass involving long-axis LV motion is a highly reproducible method, resulting in smaller LV volumes, higher ejection fraction and calculated LV mass.

  15. Latitudinal and longitudinal dispersion of energetic auroral protons

    Directory of Open Access Journals (Sweden)

    D. A. Lorentzen

    Full Text Available Using a collision by collision model from Lorentzen et al., the latitudinal and longitudinal dispersion of single auroral protons are calculated. The proton energies varies from 1 to 50 keV, and are released into the atmosphere at 700 km altitude. The dipole magnetic field has a dip-angle of 8 degrees. Results show that the main dispersion region is at high altitudes (300-350 km and occurs during the first few charge exchange collisions. As the proton travels further down the atmosphere the mean free path becomes smaller, and as a result the spreading effect will not be as pronounced. This means that the first few charge exchange collisions fully determines the width of both the latitudinal and longitudinal dispersion. The volume emission rate was calculated for energies between 1 and 50 keV, and it was found that dayside auroral hydrogen emissions rates were approximately 10 times weaker than nightside emission rates. Simulations were also performed to obtain the dependence of the particle dispersion as a function of initial pitch-angle. It was found that the dispersion varies greatly with initial pitch-angle, and the results are summarized in two tables; a main and an extreme dispersion region.

    Key words. Ionosphere (auroral ionosphere; · particle precipitation · Space plasma physics · (transport processes

  16. Longitudinal association between marital disruption and child BMI and obesity.

    Science.gov (United States)

    Arkes, Jeremy

    2012-08-01

    This research examines whether family disruptions (i.e., divorces and separation) contribute to children's weight problems. The sample consists of 7,299 observations for 2,333 children, aged 5-14, over the 1986-2006 period, from a US representative sample from the Child and Young Adult Survey accompanying the National Longitudinal Survey of Youth (NLSY). The study uses individual-fixed-effects models in a longitudinal framework to compare children's BMI and weight problems before and after a disruption. Furthermore, besides doing a before-after comparison for children, the study also estimates the effects at various periods relative to the disruption in order to examine whether children are affected before the disruption and whether any effects change as time passes from the disruption, as some effects may be temporary or slow to develop. Despite having a larger sample than the previous studies, the results provide no evidence that, on average, children's BMI and BMI percentile scores (measured with continuous outcomes) are affected before the disruption, after the disruption, and as time passes from the disruption, relative to a baseline period a few years before the disruption. However, children experiencing a family disruption do have an increased risk of obesity (having a BMI percentile score of 95 or higher) in the two years leading up to the disruption as well as after the disruption, and as time passes from the disruption.

  17. Bolted flanged connections subjected to longitudinal bending moments

    International Nuclear Information System (INIS)

    Blach, A.E.

    1992-01-01

    Flanges in piping systems and also pressure vessel flanges on tall columns are often subjected to longitudinal bending moments of considerable magnitude, be it from thermal expansion stresses in piping systems or from wind or seismic loadings on tall vertical pressure vessels. Except for the ASME Code, Section III, Subsections NB, NC, and ND, other pressure vessel and piping codes do not contain design ASME Nuclear Power Plant Code (Section III), an empirical formula is given, expressing a longitudinal bending moment in bolted flanged connections in terms of an equivalent internal pressure to be added to the design pressure of the flange. In this paper, an attempt is made to analyse the stresses on flanges and bolting due to external bending moments and to compare flange thicknesses thus obtained with thicknesses required using the equivalent design pressure specified in Subsections NB, NC, and ND. A design method is proposed, based on analysis and experimental work, which may be suitable for flange bending moment analysis when the rules of the Nuclear Power Plant Code are not mandatory. (orig.)

  18. Postural changes in dental hygienists. Four-year longitudinal study.

    Science.gov (United States)

    Barry, R M; Woodall, W R; Mahan, J M

    1992-01-01

    Numerous surveys identify the occurrence of musculoskeletal complaints as a concern in dentistry. However, no longitudinal data exist to indicate whether postural changes occur as a result of practicing dental hygiene. The purpose of this preliminary, four-year longitudinal study was to investigate whether any postural changes developed during the hygienists' clinical education and/or during subsequent dental hygiene practice after one and/or two years. It was anticipated that the awkward positions and intense physical demands placed on hygienists might initiate musculoskeletal problems, but that no postural changes would occur over this short period of time. Nine of 10 dental hygienists in the graduating class of 1987 were surveyed for existing musculoskeletal complaints, and the subjects were photographed for a measurement of postural change. Responses from participants indicated an increase in musculoskeletal-related complaints in each of the six areas investigated. The photographic findings indicated that one of the nine hygienists showed an increase in forward head posture, a postural change.

  19. Longitudinal emittance reduction in LEIR of ion beams for LHC

    CERN Document Server

    Angoletta, M E; Findlay, A; Hancock, S; Manglunki, D

    2014-01-01

    For the 2013 LHC ion run the anticipated request for batches from the PS Complex comprising four ion bunches spaced by 100 ns was changed to batches of two bunches spaced by 200 ns. This modified demand was met by suppressing a splitting step in the PS machine, but with the consequence of halving the longitudinal emittance required from LEIR. Thus NOMINAL Pb54+ beams from LEIR had to be delivered inside ~9 eVs to provide sufficient blow-up margin in the PS. Machine Development (MD) sessions were carried out in LEIR to investigate methods to satisfy these stricter requirements. Two main ingredients were found to reduce longitudinal emittance. The first and most important was to adjust carefully the frequency offset at capture in order to align the RF with the position where the beam is deposited by the electron cooling system prior to acceleration. The second ingredient was to reduce the final bucket area in order to reduce any residual filamentation during capture. This note documents the results obtaine...

  20. Correlating Function and Imaging Measures of the Medial Longitudinal Fasciculus.

    Directory of Open Access Journals (Sweden)

    Ken Sakaie

    Full Text Available To test the validity of diffusion tensor imaging (DTI measures of tissue injury by examining such measures in a white matter structure with well-defined function, the medial longitudinal fasciculus (MLF. Injury to the MLF underlies internuclear ophthalmoparesis (INO.40 MS patients with chronic INO and 15 healthy controls were examined under an IRB-approved protocol. Tissue integrity of the MLF was characterized by DTI parameters: longitudinal diffusivity (LD, transverse diffusivity (TD, mean diffusivity (MD and fractional anisotropy (FA. Severity of INO was quantified by infrared oculography to measure versional disconjugacy index (VDI.LD was significantly lower in patients than in controls in the medulla-pons region of the MLF (p < 0.03. FA was also lower in patients in the same region (p < 0.0004. LD of the medulla-pons region correlated with VDI (R = -0.28, p < 0.05 as did FA in the midbrain section (R = 0.31, p < 0.02.This study demonstrates that DTI measures of brain tissue injury can detect injury to a functionally relevant white matter pathway, and that such measures correlate with clinically accepted evaluation indices for INO. The results validate DTI as a useful imaging measure of tissue integrity.

  1. Longitudinal course of cortical thickness decline in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Schuster, Christina; Kasper, Elisabeth; Machts, Judith; Bittner, Daniel; Kaufmann, Jörn; Benecke, Reiner; Teipel, Stefan; Vielhaber, Stefan; Prudlo, Johannes

    2014-10-01

    To determine longitudinal rates of cortical atrophy in classical Amyotrophic lateral sclerosis (ALS) and ALS variants. Rates of cortical thinning were determined between 2 scans, 3-15 months apart, in 77 ALS patients: 51 classical, 12 upper motor neuron (UMN), and 14 lower motor neuron (LMN) ALS variants. Cortical thickness at the first assessment was compared with 60 healthy controls matched by age and gender. Atrophy rates were compared between patient sub-groups and correlated with disease duration, progression, and severity. Using a cross-sectional analysis, we found a significant difference in cortical thickness between ALS patients and controls in the motor and extra-motor areas (left medial orbito frontal gyrus, left inferior parietal gyrus, bilateral insular cortex, right fusiform gyrus, bilateral precuneus). Using a longitudinal analysis, we found a significant decline of cortical thickness in frontal, temporal, and parietal regions over the course of the study in ALS patients. Effects were independent of the clinical subtype, with exception of the precentral gyrus (p gyrus, the UMN-dominant subjects exhibited intermediate rates of atrophy, and the classical ALS patients exhibited no such change. Atrophy of the precentral gyrus in classical ALS indicates a floor effect at the first assessment, resulting in a lack of further atrophy over time. Structural loss of the precentral gyrus appears to be an early sign of classical ALS. Over time, patterns of cortical thinning in extra-motor areas can be identified in ALS, regardless of the phenotype.

  2. The Australian longitudinal study on male health-methods

    Directory of Open Access Journals (Sweden)

    Dianne Currier

    2016-10-01

    Full Text Available Abstract Background The Australian Longitudinal Study on Male Health (Ten to Men was established in 2011 to build the evidence base on male health to inform policy and program development. Methods Ten to Men is a national longitudinal study with a stratified multi-stage cluster random sample design and oversampling in rural and regional areas. Household recruitment was conducted from October 2013 to July 2014. Males who were aged 10 to 55 years residing in private dwellings were eligible to participate. Data were collected via self-completion paper questionnaires (participants aged 15 to 55 and by computer-assisted personal interview (boys aged 10 to 14. Household and proxy health data for boys were collected from a parent via a self-completion paper-based questionnaire. Questions covered socio-demographics, health status, mental health and wellbeing, health behaviours, social determinants, and health knowledge and service use. Results A cohort of 15,988 males aged between 10 and 55 years was recruited representing a response fraction of 35 %. Conclusion Ten to Men is a unique resource for investigating male health and wellbeing. Wave 1 data are available for approved research projects.

  3. Longitudinal Relations Between Constructive and Destructive Conflict and Couples’ Sleep

    Science.gov (United States)

    El-Sheikh, Mona; Koss, Kalsea J.; Kelly, Ryan J.; Rauer, Amy J.

    2016-01-01

    We examined longitudinal relations between interpartner constructive (negotiation) and destructive (psychological and physical aggression) conflict strategies and couples’ sleep over 1 year. Toward explicating processes of effects, we assessed the intervening role of internalizing symptoms in associations between conflict tactics and couples’ sleep. Participants were 135 cohabiting couples (M age = 37 years for women and 39 years for men). The sample included a large representation of couples exposed to economic adversity. Further, 68% were European American and the remainder were primarily African American. At Time 1 (T1), couples reported on their conflict and their mental health (depression, anxiety). At T1 and Time 2, sleep was examined objectively with actigraphs for 7 nights. Three sleep parameters were derived: efficiency, minutes, and latency. Actor–partner interdependence models indicated that husbands’ use of constructive conflict forecasted increases in their own sleep efficiency as well as their own and their wives’ sleep duration over time. Actor and partner effects emerged, and husbands’ and wives’ use of destructive conflict strategies generally predicted worsening of some sleep parameters over time. Several mediation and intervening effects were observed for destructive conflict strategies. Some of these relations reveal that destructive conflict is associated with internalizing symptoms, which in turn are associated with some sleep parameters longitudinally. These findings build on a small, albeit growing, literature linking sleep with marital functioning, and illustrate that consideration of relationship processes including constructive conflict holds promise for gaining a better understanding of factors that influence the sleep of men and women. PMID:25915089

  4. Risk and protective factors, longitudinal research, and bullying prevention.

    Science.gov (United States)

    Ttofi, Maria M; Farrington, David P

    2012-01-01

    This chapter presents the results from two systematic/meta-analytic reviews of longitudinal studies on the association of school bullying (perpetration and victimization) with adverse health and criminal outcomes later in life. Significant associations between the two predictors and the outcomes are found even after controlling for other major childhood risk factors that are measured before school bullying. The results indicate that effective antibullying programs should be encouraged. They could be viewed as a form of early crime prevention as well as an early form of public health promotion. The findings from a systematic/meta-analytic review on the effectiveness of antibullying programs are also presented. Overall, school-based antibullying programs are effective, leading to an average decrease in bullying of 20 to 23 percent and in victimization of 17 to 20 percent. The chapter emphasizes the lack of prospective longitudinal research in the area of school bullying, which does not allow examination of whether any given factor (individual, family,. or social) is a correlate, a predictor, or a possible cause for bullying. This has important implications for future antibullying initiatives, as well as implications for the refinement of theories of school bullying. It is necessary to extend the framework of the traditional risk-focused approach by incorporating the notion of resiliency and investigating possible protective factors against school bullying and its negative consequences. Copyright © 2012 Wiley Periodicals, Inc., A Wiley Company.

  5. Change in adult self-esteem: a longitudinal assessment.

    Science.gov (United States)

    Schafer, R B; Keith, P M

    1999-09-01

    This is a longitudinal investigation of self-esteem change in an adult population. The analysis addresses two limitations in earlier studies: the use of convenience samples of children and adolescents, and cross-sectional or short-duration longitudinal studies of self-esteem change. Participants are 97 randomly selected married couples interviewed at two points in time separated by 13 years. Two components of the self were measured: self-esteem and reflected appraisals (perception of others' evaluation). Contrary to previous research on self-esteem change, a significant decline was found in all components of the self for both husbands and wives. The decline in self-esteem was not a function of age, education or income. The decline was more likely to occur for high, rather than low, self-esteem participants. This finding is attributed to the demands on higher self-esteem participants to maintain or enhance self-esteem and the caution of low self-esteem participants to engage in behaviours that would threaten the self.

  6. Writing Abilities Longitudinally Predict Academic Outcomes of Adolescents with ADHD

    Science.gov (United States)

    Molitor, Stephen J.; Langberg, Joshuah M.; Bourchtein, Elizaveta; Eddy, Laura D.; Dvorsky, Melissa R.; Evans, Steven W.

    2016-01-01

    Students with ADHD often experience a host of negative academic outcomes and deficits in reading and mathematics abilities contribute to these academic impairments. Students with ADHD may also have difficulties with written expression but there has been minimal research in this area and it is not clear whether written expression abilities uniquely contribute to the academic functioning of students with ADHD. The current study included a sample of 104 middle school students diagnosed with ADHD (grades 6–8). Participants were followed longitudinally to evaluate whether written expression abilities at baseline predicted student GPA and parent ratings of academic impairment 18 months later, after controlling for reading ability and additional relevant covariates. Written expression abilities longitudinally predicted both academic outcomes above and beyond ADHD and ODD symptoms, medication use, reading ability, and baseline values of GPA and parent-rated academic impairment. Follow-up analyses revealed that no single aspect of written expression was demonstrably more impactful on academic outcomes than the others, suggesting that writing as an entire process should be the focus of intervention. PMID:26783650

  7. Developing a longitudinal cancer nursing education program in Honduras.

    Science.gov (United States)

    Sheldon, Lisa Kennedy; Wise, Barbara; Carlson, Julie R; Dowds, Cynthia; Sarchet, Vanessa; Sanchez, Jose Angel

    2013-12-01

    The present paper is a longitudinal study which aims to develop and deliver cancer nursing education conferences in Honduras using volunteer nurse educators. This program intends to (1) perform site assessments of work environments and resources for cancer care in Honduras, (2) develop cancer nursing education programs, (3) survey conference participants continuing education needs, (4) deliver cancer nursing education conferences, and (5) share data with local and global partners for future cancer programs. The study draws on a longitudinal program development with site assessments, data collection, and educational conferences at two time points. Assessments and surveys were used for conference development and delivery by volunteer nurse educators. Site assessments and conferences were delivered twice. Data were collected regarding assessments and surveys to inform program development. Survey data revealed that 65 % had internet access. Participants desired more information about handling of chemotherapy, symptom management, and palliative care. Volunteer nurse educators perform site assessments and develop educational programming for cancer nurses. Local and global partners should explore internet-based programs between site visits to create sustainable education programs.

  8. The ρ-meson longitudinal leading-twist distribution amplitude

    Directory of Open Access Journals (Sweden)

    Hai-Bing Fu

    2014-11-01

    Full Text Available In the present paper, we suggest a convenient model for the vector ρ-meson longitudinal leading-twist distribution amplitude ϕ2;ρ‖, whose distribution is controlled by a single parameter B2;ρ‖. By choosing proper chiral current in the correlator, we obtain new light-cone sum rules (LCSR for the B→ρ TFFs A1, A2 and V, in which the δ1-order ϕ2;ρ‖ provides dominant contributions. Then we make a detailed discussion on the ϕ2;ρ‖ properties via those B→ρ TFFs. A proper choice of B2;ρ‖ can make all the TFFs agree with the lattice QCD predictions. A prediction of |Vub| has also been presented by using the extrapolated TFFs, which indicates that a larger B2;ρ‖ leads to a larger |Vub|. To compare with the BABAR data on |Vub|, the longitudinal leading-twist DA ϕ2;ρ‖ prefers a doubly-humped behavior.

  9. Patient dosimetry improvements in longitudinal field MRI linear accelerators

    International Nuclear Information System (INIS)

    Oborn, B.M.; Metcalfe, P.E.; Butson, M.J.; Keall, P.

    2010-01-01

    Full text: Many studies exist of the often undesirable dosimetry changes in transverse field MRI-Linacs. Currently there are plans by different groups around the world to develop longitudinal MRT-Linac systems as dosimetry is potentially superior to transverse field sy tems. The objective of this study is to investigate via Monte Carlo simulations, the potential dosimetry improvements expected in lo gitudinal MRI-Linac designs over transverse field designs for advanced image-guided radiotherapy (IGRT). Geant4 Monte Carlo simulations have been performed of the dosimetry from a Varian 2100c 6 MV photon beam in lo gitudinal magnetic field typical of expected MRI-Linac designs. A 30 x 30 x 20 cm' phantom has been simulated in magnetic fields between 0 and 3 T. Beam profiles and skin dose calculations have been performed and compared with transverse field systems. Results The longitudinal magnetic field acts to reduce lateral dose spread in all locations within a patient. As well as this, the electron return effcct is absent. This equates to reductions in penumbral widths and reductions in skin dose. When compared with transverse field systems the dosimetry is superior. This will also allow for further reductions in trcatment margins as compared to transverse field MRI Linac designs.

  10. Association between bacterial vaginosis and partner concurrency: a longitudinal study.

    Science.gov (United States)

    Kenyon, Chris R; Buyze, Jozefien; Klebanoff, Mark; Brotman, Rebecca M

    2018-02-01

    The study aimed to test if there was an association between prevalent bacterial vaginosis (BV) and women reporting that their partner had other partners at the same time (partner concurrency). This association has not been assessed in a longitudinal cohort. The Longitudinal Study of Vaginal Flora recruited a cohort of 3620 non-pregnant women aged 15-44 years who presented for routine primary healthcare at 12 clinics in Birmingham, Alabama. Behavioural questionnaires and vaginal smears were obtained quarterly for a year and BV was defined by a Nugent score 7 or higher as well as Amsel criteria. Mixed effects logistic regression was used to assess the relationship between prevalent BV and reporting that one's partner had other partners in the preceding 3-6 months time interval. Nugent score prevalent BV was associated with both reporting that one's partner definitely (adjusted OR (aOR) 1.5; 95% CI 1.2 to 1.8) and possibly (aOR 1.5; 95% CI 1.2 to 1.8) engaged in partner concurrency in the preceding 3-6 months time period. Prevalent BV diagnosed by Amsel criteria was similar. A diagnosis of prevalent BV was associated with reporting that one's partner possibly or definitely engaged in partner concurrency. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  11. Longitudinal beam instabilities in a double RF system

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00229208; Gazis, Evangelos

    Operation with a double RF system is essential for many accelerators in order to increase beam stability, to change the bunch shape or to perform various RF manipulations. This is also the case for the operation of the CERN SPS as the LHC proton injector, where in addition to the main RF system, a fourth harmonic RF system is used in bunch shortening mode in order to increase the synchrotron frequency spread inside the bunch and thus to enhance Landau damping of the collective instabilities. In fact the double RF system operation in the SPS is one of the essential means, together with the controlled longitudinal emittance blow-up to significantly increase the longitudinal instability thresholds (single and multi-bunch) and deliver a good quality beam for the LHC. However, for the HiLumi-LHC (HL-LHC) and LHC injector upgrade (LIU) projects higher beam intensities are required. After all upgrades are in place, the main performance limitations of the LHC injector complex are beam instabilities and high intensity...

  12. LONGITUDINAL STRUCTURAL CHANGES IN LATE-ONSET RETINAL DEGENERATION.

    Science.gov (United States)

    Cukras, Catherine; Flamendorf, Jason; Wong, Wai T; Ayyagari, Radha; Cunningham, Denise; Sieving, Paul A

    2016-12-01

    To characterize longitudinal structural changes in early stages of late-onset retinal degeneration to investigate pathogenic mechanisms. Two affected siblings, both with a S163R missense mutation in the causative gene C1QTNF5, were followed for 8+ years. Color fundus photos, fundus autofluorescence images, near-infrared reflectance fundus images, and spectral domain optical coherence tomography scans were acquired during follow-up. Both patients, aged 45 and 50 years, had good visual acuities (>20/20) in the context of prolonged dark adaptation. Baseline color fundus photography demonstrated yellow-white, punctate lesions in the temporal macula that correlated with a reticular pattern on fundus autofluorescence and near-infrared reflectance imaging. Baseline spectral domain optical coherence tomography imaging revealed subretinal deposits that resemble reticular pseudodrusen described in age-related macular degeneration. During follow-up, these affected areas developed confluent thickening of the retinal pigment epithelial layer and disruption of the ellipsoid zone of photoreceptors before progressing to overt retinal pigment epithelium and outer retinal atrophy. Structural changes in early stages of late-onset retinal degeneration, revealed by multimodal imaging, resemble those of reticular pseudodrusen observed in age-related macular degeneration and other retinal diseases. Longitudinal follow-up of these lesions helps elucidate their progression to frank atrophy and may lend insight into the pathogenic mechanisms underlying diverse retinal degenerations.

  13. Transformational Leadership and Incivility: A Multilevel and Longitudinal Test.

    Science.gov (United States)

    Bureau, Julien S; Gagné, Marylène; Morin, Alexandre J S; Mageau, Geneviève A

    2017-10-01

    This research examines group-level perceptions of transformational leadership (TFL) as negative longitudinal predictors of witnessing person-related (e.g., insults/affronts) and work-related (e.g., negation/intentional work overload) acts of incivility at work. Witnessing workplace incivility was also postulated to negatively predict employee need satisfaction. Data were collected among production employees in different Canadian plants of a major manufacturing company ( N = 344) who worked for 42 different managers ( M group size = 9.76). Two waves of data collection occurred 1 year apart. Results from multilevel analyses showed that workgroups where managers were perceived to engage in more frequent TFL behaviors reported reduced levels of person- and work-related incivility 1 year later. However, group-level incivility did not predict change in group-level need satisfaction 1 year later. At the individual level, results showed that witnessing higher levels of person-related incivility than one's colleagues predicted reduced satisfaction of the need for relatedness 1 year later. These longitudinal findings build upon previous literature by identifying TFL as a potential managerial strategy to reduce incivility in workgroups over time. They also show that mere exposure to workplace misbehavior still affects employees' adjustment, suggesting that every effort to reduce deviance in workplaces is worthwhile.

  14. Mindful Parenting and Emotion Socialization Practices: Concurrent and Longitudinal Associations.

    Science.gov (United States)

    McKee, Laura G; Parent, Justin; Zachary, Chloe R; Forehand, Rex

    2017-11-01

    Caregivers play a crucial role in the socialization of youth emotion understanding, competence, and regulation, which are implicated in youth social and emotional health; however, there is less understanding of parental psychosocial or cognitive factors, like mindful parenting, that may be associated with the use of particular emotion socialization (ES) strategies. This study tests a model of the cross-sectional and short-term longitudinal associations between mindful parenting and supportive and nonsupportive ES strategies in a community sample of parents (N = 246; 63.8% mothers) of youth ranging from ages 3-12. Caregivers reported on mindful parenting and ES strategies at two time points 4 months apart. The structural equation model indicated that higher levels of mindful parenting are positively related to supportive ES responses and negatively related to nonsupportive ES responses both concurrently and over time. The longitudinal association between mindful parenting and nonsupportive, but not supportive, ES was marginally larger for fathers as compared to mothers. Given the documented impact of ES strategies on youth emotional and behavioral outcomes and interventions emerging to educate parents about how to provide a healthy emotional atmosphere, incorporating a focus on mindful parenting strategies may provide one pathway to increase supportive responses and decrease nonsupportive ones. © 2017 Family Process Institute.

  15. Longitudinal muscle of the esophagus: its role in esophageal health and disease.

    Science.gov (United States)

    Mittal, Ravinder K

    2013-07-01

    The muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. The function of the longitudinal muscle and its role in bolus propulsion are not clear. The goal of this review is to summarize what is known of the role of the longitudinal muscle in health, as well as in sensory and motor disorders of the esophagus. Simultaneous manometry and ultrasound imaging reveal that, during peristalsis, the two muscle layers of the esophagus contract in perfect synchrony. On the contrary, during transient lower esophageal sphincter (LES) relaxation, longitudinal muscle contracts independent of the circular muscle. Recent studies have provided novel insights into the role of the longitudinal muscle in LES relaxation and descending relaxation of the esophagus. In certain diseases (e.g. some motility disorders of the esophagus), there is discoordination between the two muscle layers, which likely plays an important role in the genesis of dysphagia and delayed esophageal emptying. There is close temporal correlation between prolonged contractions of the longitudinal muscles of the esophagus and esophageal 'angina-like' pain. Novel techniques to record longitudinal muscle contraction are reviewed. Longitudinal muscles of the esophagus play a key role in the physiology and pathophysiology of esophageal sensory and motor function. Neuro-pharmacologic controls of circular and longitudinal muscle are different, which provides an opportunity for the development of novel pharmacological therapies in the treatment of esophageal sensory and motor disorders.

  16. Longitudinal Gradients in Phosphorus Characteristics in the Minnesota-Upper Mississippi River System

    National Research Council Canada - National Science Library

    James, William

    2002-01-01

    This technical note describes longitudinal patterns in soluble phosphorus and biologically available particulate phosphorus and equilibrium characteristics for suspended sediment collected at stations...

  17. Effect of loading pattern on longitudinal bowing in flexible roll forming

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Hyun; Woo, Young Yun; Hwang, Tae Woo; Han, Sang Wook; Moon, Young Hoon [School of Mechanical Engineering, Engineering Research Center for Net Shape and Die Manufacturing, Pusan National University,Busan (Korea, Republic of)

    2016-12-15

    The flexible roll forming process can be used to fabricate products with a variable cross-section profile in the longitudinal direction. Transversal nonuniformity of the longitudinal strain is one of the fundamental characteristics of blank deformation in flexible roll forming. Longitudinal bowing is a shape defect caused by transversal nonuniformity of the longitudinal strain. In this study, loading patterns in flexible roll forming are investigated in order to reduce the longitudinal bowing in a roll-formed blank. To analyze the effects of loading patterns on longitudinal bowing, two different forming schedules are implemented. In schedule 1, loading patterns with different bending angle increments are designed under fixed initial and final bending angles. In schedule 2, loading patterns with different initial bending angles under the fixed final bending angle are designed. Our results show that the bowing heights are significantly affected by the loading patterns. The bowing susceptibilities vary with blank shape such as trapezoid, convex, and concave shapes. In addition to the peak longitudinal strain at the respective roll stands, the cumulative longitudinal strain from the initial to final stands is shown to be a reliable index in predicting the tendency of longitudinal bowing.

  18. Longitudinal multigroup invariance analysis of the satisfaction with food-related life scale in university students.

    Science.gov (United States)

    Schnettler, Berta; Miranda, Horacio; Miranda-Zapata, Edgardo; Salinas-Oñate, Natalia; Grunert, Klaus G; Lobos, Germán; Sepúlveda, José; Orellana, Ligia; Hueche, Clementina; Bonilla, Héctor

    2017-06-01

    This study examined longitudinal measurement invariance in the Satisfaction with Food-related Life (SWFL) scale using follow-up data from university students. We examined this measure of the SWFL in different groups of students, separated by various characteristics. Through non-probabilistic longitudinal sampling, 114 university students (65.8% female, mean age: 22.5) completed the SWFL questionnaire three times, over intervals of approximately one year. Confirmatory factor analysis was used to examine longitudinal measurement invariance. Two types of analysis were conducted: first, a longitudinal invariance by time, and second, a multigroup longitudinal invariance by sex, age, socio-economic status and place of residence during the study period. Results showed that the 3-item version of the SWFL exhibited strong longitudinal invariance (equal factor loadings and equal indicator intercepts). Longitudinal multigroup invariance analysis also showed that the 3-item version of the SWFL displays strong invariance by socio-economic status and place of residence during the study period over time. Nevertheless, it was only possible to demonstrate equivalence of the longitudinal factor structure among students of both sexes, and among those older and younger than 22 years. Generally, these findings suggest that the SWFL scale has satisfactory psychometric properties for longitudinal measurement invariance in university students with similar characteristics as the students that participated in this research. It is also possible to suggest that satisfaction with food-related life is associated with sex and age. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Joint Models for Longitudinal and Time-to-Event Data With Applications in R

    CERN Document Server

    Rizopoulos, Dimitris

    2012-01-01

    In longitudinal studies it is often of interest to investigate how a marker that is repeatedly measured in time is associated with a time to an event of interest, e.g., prostate cancer studies where longitudinal PSA level measurements are collected in conjunction with the time-to-recurrence. Joint Models for Longitudinal and Time-to-Event Data: With Applications in R provides a full treatment of random effects joint models for longitudinal and time-to-event outcomes that can be utilized to analyze such data. The content is primarily explanatory, focusing on applications of joint modeling, but

  20. Longitudinal effects of medical students' communication skills on future performance.

    Science.gov (United States)

    Dong, Ting; LaRochelle, Jeffrey S; Durning, Steven J; Saguil, Aaron; Swygert, Kimberly; Artino, Anthony R

    2015-04-01

    The Essential Elements of Communication (EEC) were developed from the Kalamazoo consensus statement on physician-patient communication. The Uniformed Services University of the Health Sciences (USU) has adopted a longitudinal curriculum to use the EEC both as a learning tool during standardized patient encounters and as an evaluation tool culminating with the end of preclerkship objective-structured clinical examinations (OSCE). Medical educators have recently emphasized the importance of teaching communication skills, as evidenced by the United States Medical Licensing Examination testing both the integrated clinical encounter (ICE) and communication and interpersonal skills (CIS) within the Step 2 Clinical Skills exam (CS). To determine the associations between students' EEC OSCE performance at the end of the preclerkship period with later communication skills assessment and evaluation outcomes in the context of a longitudinal curriculum spanning both undergraduate medical education and graduate medical education. Retrospective data from preclerkship (overall OSCE scores and EEC OSCE scores) and clerkship outcomes (internal medicine [IM] clinical points and average clerkship National Board of Medical Examiners [NBME] scores) were collected from 167 USU medical students from the class of 2011 and compared to individual scores on the CIS and ICE components of Step 2 CS, as well as to the communication skills component of the program directors' evaluation of trainees during their postgraduate year 1 (PGY-1) residency. In addition to bivariate Pearson correlation analysis, we conducted multiple linear regression analysis to examine the predictive power of the EEC score beyond the IM clerkship clinical points and the average NBME Subject Exams score on the outcome measures. The EEC score was a significant predictor of the CIS score and the PGY-1 communication skills score. Beyond the average NBME Subject Exams score and the IM clerkship clinical points, the EEC score

  1. Longitudinal relaxation of initially straight flexible and stiff polymers

    Science.gov (United States)

    Dimitrakopoulos, Panagiotis; Dissanayake, Inuka

    2004-11-01

    The present talk considers the relaxation of a single flexible or stiff polymer chain from an initial straight configuration in a viscous solvent. This problem commonly arises when strong flows are turned off in both industrial and biological applications. The problem is also motivated by recent experiments with single biopolymer molecules relaxing after being fully extended by applied forces as well as by the recent development of micro-devices involving stretched tethered biopolymers. Our results are applicable to a wide array of synthetic polymers such as polyacrylamides, Kevlar and polyesters as well as biopolymers such as DNA, actin filaments, microtubules and MTV. In this talk we discuss the mechanism of the polymer relaxation as was revealed through Brownian Dynamics simulations covering a broad range of time scales and chain stiffness. After the short-time free diffusion, the chain's longitudinal reduction at early intermediate times is shown to constitute a universal behavior for any chain stiffness caused by a quasi-steady relaxation of tensions associated with the deforming action of the Brownian forces. Stiff chains are shown to exhibit a late intermediate-time longitudinal reduction associated with a relaxation of tensions affected by the deforming Brownian and the restoring bending forces. The longitudinal and transverse relaxations are shown to obey different laws, i.e. the chain relaxation is anisotropic at all times. In the talk, we show how from the knowledge of the relaxation mechanism, we can predict and explain the polymer properties including the polymer stress and the solution birefringence. In addition, a generalized stress-optic law is derived valid for any time and chain stiffness. All polymer properties which depend on the polymer length are shown to exhibit two intermediate-time behaviors with the early one to constitute a universal behavior for any chain stiffness. This work was supported in part by the Minta Martin Research Fund. The

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

    Science.gov (United States)

    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.

  3. Longitudinal Trajectory of Exposure to Psychological Interpersonal Violence.

    Science.gov (United States)

    Poehacker, Stefanie; Phillips, David; Riggs, Jessica; Lauterbach, Dean

    2017-05-01

    Psychological intimate partner violence (P-IPV) refers to verbal abuse from one partner to another and abuse of power or control from one partner to another. To date, no studies have examined the longitudinal course of P-IPV exposure among mothers or the effect that witnessing P-IPV can have on their children. Using latent class growth analysis, the current study identified five trajectory groups with the following intercept and growth characteristics: low stable, low-increasing, moderate-decreasing, high-decreasing, and consistently elevated. Membership in the four groups characterized by higher P-IPV exposure was predicted by maternal race and exposure to physical abuse. The children of mothers in the low-increasing and consistently elevated groups had elevated scores on the Internalizing and Externalizing scales of the Childhood Behavior Checklist. These findings remained after controlling for child sex, race, cumulative trauma exposure, and maternal depression.

  4. Primary subfertility with partial septate uterus and longitudinal vaginal septum

    Directory of Open Access Journals (Sweden)

    Jesmine Banu

    2017-02-01

    Full Text Available A 22 year old married woman presented with the complaints of severe dyspareunia, difficulty in conceiving for 18 months, menorrhagia and dysmenorrhoea since menarche. Clinical examination revealed longitudinal vaginal septum. Ultrasound scan revealed two endometrial cavities with a single cervix. Hysterosalpingogram revealed septum which had separated the endometrial cavity with no free spillage of contrast media on both fallopian tubes. Ultrasound KUB and intravenous urethrography did not reveal any abnormality in the urinary system. Resection of vaginal septum, hysteroscopic septoplasty and diagnostic laparoscopy were performed. Three months after the surgery, she was relieved from the symptoms. However, no comments on fertility issue can be made at the moment as the couple is practicing contraceptive methods.

  5. Overview of national attitudes toward nuclear energy: a longitudinal analysis

    International Nuclear Information System (INIS)

    Rankin, W.L.

    1982-01-01

    The purpose of this paper is to present a longitudinal overview of public attitudes toward nuclear power development in the United States. Over ten years of attitudinal data are now available for analysis of the stability of such attitudes over time. These data are useful to many people, including policy makers in government, nuclear industry decision makers, and public action groups that support and oppose nuclear power. This information is also useful in checking the claims of those who purport to be speaking for the public. The level of public acceptance for nuclear power in the near term and into the next century can only be estimated at this time. But this estimate can be based on nearly a decade of survey research

  6. Intercalibration of the longitudinal segments of a calorimeter system

    International Nuclear Information System (INIS)

    Albrow, M.; Aota, S.; Apollinari, G.; Asakawa, T.; Bailey, M.; Barbaro, P. de; Barnes, V.; Benjamin, D.; Blusk, S.; Bodek, A.; Bolla, G.; Budd, H.; Cauz, D.; Demortier, L.; Fukui, Y.; Gotra, Y.; Hahn, S.; Handa, T.; Hatakeyama, K.; Ikeda, H.; Introzzi, G.; Iwai, J.; Kim, S.H.; Koengeter, A.; Kowald, W.; Laasanen, A.; Lamoureux, J.; Lindgren, M.; Liu, J.; Lobban, O.; Melese, P.; Minato, H.; Murgia, S.; Nakada, H.; Patrick, J.; Pauletta, G.; Sakumoto, W.; Santi, L.; Seiya, Y.; Solodsky, A.; Spiegel, L.; Thomas, T.; Vilar, R.; Walsh, A.M.; Wigmans, R.

    2002-01-01

    Three different methods of setting the hadronic energy scale of a longitudinally segmented calorimeter system are compared with each other. The merits of these methods have been studied with test beam data from the CDF Plug Upgrade Calorimeter. It turns out that one of the (commonly used) calibration methods introduces a number of undesirable side effects, such as an increased hadronic signal nonlinearity and trigger biases resulting from the fact that the reconstructed energy of hadrons depends on the starting point of their showers. These problems can be avoided when a different calibration method is used. The results of this study are applied to determine the e/h values of the calorimeter and its segments

  7. Coherent Nonlinear Longitudinal Phenomena in Unbunched Synchrotron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Spentzouris, Linda Klamp [Northwestern U.

    1996-12-01

    Coherent nonlinear longitudinal phenomena are studied in proton and antiproton synchrotron beams. Theoretical development done in the eld of plasma physics for resonant wave-wave coupling is applied to the case of a particle beam. Results are given from experiments done to investigate the nature of the weakly nonlinear three-wave coupling processes known as parametric coupling and echoes. Storage ring impedances are shown to amplify the parametric coupling process, underlining the possibility that machine impedances might be extracted from coupling events instigated by external excitation. Echo amplitudes are demonstrated to be sensitive to diusion processes, such as intrabeam scattering, which degrade a beam. The result of a fast diusion rate measurement using echo amplitudes is presented. In addition to the wave-wave interactions, observations of moderately nonlinear waveparticle interactions are also included. The manifestations of these interactions that are documented include nonlinear Landau damping, higher harmonic generation, and signs of the possible formation of solitons.

  8. Religiousness and Longitudinal Trajectories in Elders' Functional Status

    Science.gov (United States)

    Park, Nan Sook; Klemmack, David L.; Roff, Lucinda L.; Parker, Michael W.; Koenig, Harold G.; Sawyer, Patricia; Allman, Richard M.

    2010-01-01

    The purpose of this study was to examine the effects of religiousness on the trajectories of difficulties with activities of daily living (ADLs) and instrumental ADLs (IADLs) in community-dwelling older adults over a three-year period. Seven waves of data from the University of Alabama at Birmingham Study of Aging were analyzed using a hierarchical linear modeling method. The study was based on the 784 participants who completed interviews every six months between December 1999 and February 2004. Frequent religious service attendance was associated with fewer ADL difficulties and IADL difficulties at baseline. Furthermore, religious service attendance predicted slower increases for frequent churchgoers and steeper increases for less frequent churchgoers in IADL difficulties, controlling for variables related to demographics and resources. Religious service attendance was independently associated with ADL and IADL difficulties cross-sectionally. However, significant protective effects of religious service attendance were identified longitudinally only for the IADL trajectory. PMID:20485460

  9. A longitudinal study of memory advantages in bilinguals.

    Directory of Open Access Journals (Sweden)

    Jessica K Ljungberg

    Full Text Available Typically, studies of cognitive advantages in bilinguals have been conducted previously by using executive and inhibitory tasks (e.g. Simon task and applying cross-sectional designs. This study longitudinally investigated bilingual advantages on episodic memory recall, verbal letter and categorical fluency during the trajectory of life. Monolingual and bilingual participants (n=178 between 35-70 years at baseline were drawn from the Betula Prospective Cohort Study of aging, memory, and health. Results showed that bilinguals outperformed monolinguals at the first testing session and across time both in episodic memory recall and in letter fluency. No interaction with age was found indicating that the rate of change across ages was similar for bilinguals and monolinguals. As predicted and in line with studies applying cross-sectional designs, no advantages associated with bilingualism were found in the categorical fluency task. The results are discussed in the light of successful aging.

  10. Twisted-Light-Ion Interaction: The Role of Longitudinal Fields

    Science.gov (United States)

    Quinteiro, G. F.; Schmidt-Kaler, Ferdinand; Schmiegelow, Christian T.

    2017-12-01

    The propagation of light beams is well described using the paraxial approximation, where field components along the propagation direction are usually neglected. For strongly inhomogeneous or shaped light fields, however, this approximation may fail, leading to intriguing variations of the light-matter interaction. This is the case of twisted light having opposite orbital and spin angular momenta. We compare experimental data for the excitation of a quadrupole transition in a single trapped 40Ca+ ion from Schmiegelow et al. [Nat. Commun. 7, 12998 (2016), 10.1038/ncomms12998] with a complete model where longitudinal components of the electric field are taken into account. Our model matches the experimental data and excludes by 11 standard deviations the approximation of a complete transverse field. This demonstrates the relevance of all field components for the interaction of twisted light with matter.

  11. Longitudinal and transverse electric field measurements in resonant cavities

    International Nuclear Information System (INIS)

    Tong Dechun; Chen Linfeng; Zheng Xiaoyue

    1994-01-01

    The paper presents a measuring technique for the electric field distribution of high order modes in resonant cavities. A perturbing bead-like cage made with metallic wires are developed for S-band field measurements, which can be used to detect a small electric field component in the presence of other strong electric or magnetic field components (That means high sensitivity and high directivity). In order to avoid orientation error for the cage with very high directivity, two parallel threads were used for supporting the perturbing cage. A simple mechanical set-up is described. The cage can be driven into the cavity on-axis or off-axis in any azimuth for the longitudinal and transverse electric field measurements

  12. Kinetic theory of a longitudinally expanding system of scalar particles

    International Nuclear Information System (INIS)

    Epelbaum, Thomas; Gelis, François; Jeon, Sangyong; Moore, Guy; Wu, Bin

    2015-01-01

    A simple kinematical argument suggests that the classical approximation may be inadequate to describe the evolution of a system with an anisotropic particle distribution. In order to verify this quantitatively, we study the Boltzmann equation for a longitudinally expanding system of scalar particles interacting with a ϕ 4 coupling, that mimics the kinematics of a heavy ion collision at very high energy. We consider only elastic 2→2 scatterings, and we allow the formation of a Bose-Einstein condensate in overpopulated situations by solving the coupled equations for the particle distribution and the particle density in the zero mode. For generic CGC-like initial conditions with a large occupation number, the solutions of the full Boltzmann equation cease to display the classical attractor behavior sooner than expected; for moderate coupling, the solutions appear never to follow a classical attractor solution.

  13. A longitudinal study of adult foreign language learning

    DEFF Research Database (Denmark)

    Nielsen, Andreas Højlund; Horn, Nynne Thorup; Sørensen, Stine Derdau

    Models of speech learning suggest that adaptations to foreign language sound categories should happen early in the acquisition process. Results from laboratory language training show effects on non-native perception within one to three weeks of training. Results from linguistic immersion studies...... show differences in adaptations when contrasting averages of 1-2 yrs of experience with 6-7 yrs of experience. We investigated this apparent discrepancy in a longitudinal study on Danish language officer cadets learning either Arabic (MSA and Egyptian dialect) or Dari (Afghan Farsi) through intensive...... (emphatic frication) and a phonemic Dari contrast (fricative voicing) as stimuli for both groups. We saw an effect of learning on the Dari learners’ identification of the Dari stimuli already after three weeks of language training, which was sustained, but not improved, after six and 20 months. The extents...

  14. Tunable Laser Plasma Accelerator based on Longitudinal Density Tailoring

    Energy Technology Data Exchange (ETDEWEB)

    Gonsalves, Anthony; Nakamura, Kei; Lin, Chen; Panasenko, Dmitriy; Shiraishi, Satomi; Sokollik, Thomas; Benedetti, Carlo; Schroeder, Carl; Geddes, Cameron; Tilborg, Jeroen van; Osterhoff, Jens; Esarey, Eric; Toth, Csaba; Leemans, Wim

    2011-07-15

    Laser plasma accelerators have produced high-quality electron beams with GeV energies from cm-scale devices and are being investigated as hyperspectral fs light sources producing THz to {gamma}-ray radiation and as drivers for future high-energy colliders. These applications require a high degree of stability, beam quality and tunability. Here we report on a technique to inject electrons into the accelerating field of a laser-driven plasma wave and coupling of this injector to a lower-density, separately tunable plasma for further acceleration. The technique relies on a single laser pulse powering a plasma structure with a tailored longitudinal density profile, to produce beams that can be tuned in the range of 100-400 MeV with percent-level stability, using laser pulses of less than 40 TW. The resulting device is a simple stand-alone accelerator or the front end for a multistage higher-energy accelerator.

  15. A longitudinal field multiple sampling ionization chamber for RIBLL2

    International Nuclear Information System (INIS)

    Tang Shuwen; Ma Peng; Lu Chengui; Duan Limin; Sun Zhiyu; Yang Herun; Zhang Jinxia; Hu Zhengguo; Xu Shanhu

    2012-01-01

    A longitudinal field MUltiple Sampling Ionization Chamber (MUSIC), which makes multiple measurements of energy loss for very high energy heavy ions at RIBLL2, has been constructed and tested with 3 constituent α source ( 239 Pu : 3.435 MeV, 241 Am : 3.913 MeV, 244 Cm : 4.356 MeV). The voltage plateau curve has been plotted and-500 V is determined as a proper work voltage. The energy resolution is 271.4 keV FWHM for the sampling unit when 3.435 MeV energy deposited. A Geant4 Monte Carlo simulation is made and it indicates the detector can provide unique particle identification for ions Z≥4. (authors)

  16. Longitudinal Lorentz force on a subwavelength-diameter optical fiber

    International Nuclear Information System (INIS)

    Yu Huakang; Fang Wei; Gu Fuxing; Yang Zongyin; Tong Limin; Qiu Min

    2011-01-01

    We analyze the longitudinal Lorentz forces that a propagating continuous-wave light exerts on a subwavelength-diameter optical fiber. Our theoretical results show that, during the propagating process, the guided light exerts no net time-averaged force on the fiber. Via numerical simulation, we find a significant overall pull force of 0.4 pN/mW acting on a 450-nm-diam fiber tip at a wavelength of 980 nm due to the scattering of the end face and a calculated force distribution reveals the feature of a near-field accumulation. Our results may be helpful to the configuration of optomechanical components or devices based on these fibers.

  17. Longitudinal Changes in Component Processes of Working Memory.

    Science.gov (United States)

    Rieckmann, Anna; Pudas, Sara; Nyberg, Lars

    2017-01-01

    Working memory (WM) entails maintenance and manipulation of information in the absence of sensory input. This study investigated the trajectories and neural basis of these component processes of WM functions in aging. Longitudinal human functional magnetic resonance imaging (fMRI) data are presented from 136 older individuals (55-80 years) who were scanned at baseline and again 4 years later. We obtained evidence that age-related changes in parietal and frontal components of the WM core network are dissociable in terms of their role in maintenance of perceptual representations and further manipulation of this information, respectively. Individual difference analyses in performance subgroups showed that only prefrontal changes in fMRI activation were accompanied by changes in performance, but parietal brain activity was related to study dropout. We discuss the results in terms of possible neurobiological causes underlying separable aging-related declines in inferior parietal cortex and lateral prefrontal cortex that differentially affect WM functions.

  18. Longitudinal Associations between Depression and Aggression in Children and Adolescents.

    Science.gov (United States)

    Blain-Arcaro, Christine; Vaillancourt, Tracy

    2017-07-01

    Due to the longstanding and detrimental effects of engaging in aggressive behaviour and of experiencing symptoms of internalizing problems in children and adolescents, there is an increasing interest in identifying the temporal sequence between these 2 problems with previous research yielding inconsistent findings. Therefore, the longitudinal links between relational aggression, physical aggression, and depression were examined across 7 years in a sample of 643 children (54 % girls) aged 10 at Time 1. Three models were compared- (1) the failure model, in which aggression predicted depression, (2) the acting out model, in which depression predicted aggression, and (3) a reciprocal model, in which both aggression and depression shared a reciprocal relation over time. Cross-lagged path analyses using structural equation modeling supported the failure model (i.e., engaging in relational and physical aggression predicts subsequent depressive symptoms). Findings were similar for boys and girls. These findings add to the literature suggesting that externalizing problems precede internalizing problems.

  19. Longitudinal- and transverse-wake-field effects in dielectric structures

    International Nuclear Information System (INIS)

    Rosing, M.; Gai, W.

    1990-01-01

    A dielectric-loaded circular waveguide structure is a potential high-gradient linear wake-field accelerator. A complete solution is given for the longitudinal electric and magnetic fields excited by a δ function and a Gaussian charge distribution moving parallel to the guide axis. The fields are then given in the limit of particle velocity equal to the speed of light. Example calculations are given for a structure with inner radius of 2 mm, outer radius of 5 mm, dielectric constant of 3, and total charge of 100 nC. Peak wake fields in excess of 200 MV/m are found. Azimuthal modes 0 and 1 are investigated for the particular interest of acceleration and deflection problems

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Kaja Irgens-Hansen

    2016-01-01

    Full Text Available 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.

  2. Evolution of longitudinal equilibrium distribution in the adiabatic regime

    International Nuclear Information System (INIS)

    Wei, J.; Lee, S.Y.; Ruggiero, A.G.

    1990-01-01

    Evolution of longitudinal equilibrium distribution of a hadron bunch under the beam-environment interaction is investigated based on a self-consistent solution of the Vlasov equation. The effect of this interaction on the distribution can be characterized by a dimensionless quantity in analogy to the one describing the microwave-instability criterion. In the case that the coupling impedance (Z/n) is reactive and frequency independent, the change in the distribution results in a stabilization that keeps the bunch below the instability threshold; microwave instability is thus eliminated. Monte Carlo simulation for the microwave instability agrees with analytic solution of the Vlasov equation provided that bunch shape distortion due to the coupling is taken into account

  3. A Longitudinal Analysis of Search Engine Index Size

    DEFF Research Database (Denmark)

    Van den Bosch, Antal; Bogers, Toine; De Kunder, Maurice

    2015-01-01

    One of the determining factors of the quality of Web search engines is the size of their index. In addition to its influence on search result quality, the size of the indexed Web can also tell us something about which parts of the WWW are directly accessible to the everyday user. We propose a novel...... method of estimating the size of a Web search engine’s index by extrapolating from document frequencies of words observed in a large static corpus of Web pages. In addition, we provide a unique longitudinal perspective on the size of Google and Bing’s indexes over a nine-year period, from March 2006...... until January 2015. We find that index size estimates of these two search engines tend to vary dramatically over time, with Google generally possessing a larger index than Bing. This result raises doubts about the reliability of previous one-off estimates of the size of the indexed Web. We find...

  4. Proximal alveolar bone loss in a longitudinal radiographic investigation

    International Nuclear Information System (INIS)

    Lavstvedt, S.; Bolin, A.; Henrikson, C.O.; Carstensen, J.

    1986-01-01

    A longitudinal radiographic investigation was made of the progression of the proximal alveolar bone loss over a 10-year period (1970-1980). The material was unselected and consisted of 669 individuals in the county of Stockholm. 61 individuals were randomly selected for evaluation of a recording system using alternative methods of measurement, and 90% of the measurement sites could then be assessed. The correlations between some of the methods were high, such as between measurement of alveolar bone height and root length and between aleveolar bone height and tooth length. To reduce the number of measurements, a partial recording was made, giving a high correlation coefficient between the partial recording and total recording. When five measurement sites were used, the correlation coefficient was 0.96, and a slight increase of the coefficient was obtained when using additional sites

  5. Acute longitudinal ligament rupture following acute spinal trauma

    Directory of Open Access Journals (Sweden)

    Donald Hansom

    2014-06-01

    Full Text Available The authors present a rare case of anterior longitudinal ligament (ALL rupture in a 47- year-old gentleman following a bicycle accident. The ALL is a continuous band of a variable thickness that acts as a primary spinal stabiliser. Stress, strain or rupture of the ALL usually occurs as a result of hyperextension, with the primary perpetrator being whiplash injuries. Such injuries have been shown to result in cervical spine instability during extension, axial rotation, and lateral bending modes. Spine radiographs of such patients may be routinely assessed as normal, therefore this specific type of injury does not lend itself to identification by traditional imaging methods. This account demonstrates the importance of having a high index of suspicion of a ligamentous neck injury in the setting of normal plain radiographs but abnormal clinical examination.

  6. Element free Galerkin formulation of composite beam with longitudinal slip

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Dzulkarnain; Mokhtaram, Mokhtazul Haizad [Department of Civil Engineering, Universiti Selangor, Bestari Jaya, Selangor (Malaysia); Badli, Mohd Iqbal; Yassin, Airil Y. Mohd [Faculty of Civil Engineering, Universiti Teknologi Malaysia, Skudai, Johor (Malaysia)

    2015-05-15

    Behaviour between two materials in composite beam is assumed partially interact when longitudinal slip at its interfacial surfaces is considered. Commonly analysed by the mesh-based formulation, this study used meshless formulation known as Element Free Galerkin (EFG) method in the beam partial interaction analysis, numerically. As meshless formulation implies that the problem domain is discretised only by nodes, the EFG method is based on Moving Least Square (MLS) approach for shape functions formulation with its weak form is developed using variational method. The essential boundary conditions are enforced by Langrange multipliers. The proposed EFG formulation gives comparable results, after been verified by analytical solution, thus signify its application in partial interaction problems. Based on numerical test results, the Cubic Spline and Quartic Spline weight functions yield better accuracy for the EFG formulation, compares to other proposed weight functions.

  7. Mild Cognitive Impairment: Diagnosis, Longitudinal Course, and Emerging Treatments

    Science.gov (United States)

    Vega, Jennifer N.; Newhouse, Paul A.

    2014-01-01

    Mild cognitive impairment (MCI) is widely regarded as the intermediate stage of cognitive impairment between the changes seen in normal cognitive aging and those associated with dementia. Elderly patients with MCI constitute a high-risk population for developing dementia, in particular Alzheimer’s disease (AD). Although the core clinical criteria for MCI have remained largely unchanged, the operational definition of MCI has undergone several revisions over the course of the last decade and remains an evolving diagnosis. Prognostic implications of this diagnosis are becoming clearer with regard to the risk of progressive cognitive deterioration. Although patients with MCI may represent an optimal target population for pharmacological and non-pharmacological interventions, results from clinical trials have been mixed and a definitive effective treatment remains elusive. This article provides a brief overview of the evolution of the concept of MCI and reviews current diagnostic criteria, the longitudinal course of the disorder, and current and emerging treatments for MCI. PMID:25160795

  8. Confounding adjustment through front-door blocking in longitudinal studies

    Directory of Open Access Journals (Sweden)

    Arvid Sjölander

    2013-03-01

    Full Text Available A common aim of epidemiological research is to estimate the causal effect of a particular exposure on a particular outcome. Towards this end, observed associations are often ‘adjusted’ for potential confounding variables. When the potential confounders are unmeasured, explicit adjustment becomes unfeasible. It has been demonstrated that causal effects can be estimated even in the presence of umeasured confounding, utilizing a method called ‘front-door blocking’. In this paper we generalize this method to longitudinal studies. We demonstrate that the method of front-door blocking poses a number of challenging statistical problems, analogous to the famous problems associ- ated with the method of ‘back-door blocking’.

  9. Heat transfer enhancement in heat exchangers by longitudinal vortex generators

    International Nuclear Information System (INIS)

    Guntermann, T.; Fiebig, M.; Mitra, N.K.

    1990-01-01

    In this paper heat transfer enhancement and flow losses are computed for the interaction of a laminar channel flow with a pair of counterrotating longitudinal vortices generated by a pair of delta-winglets punched out of the channel wall. The geometry simulates an element of a fin-plate or fin-tube heat exchanger. The structure of the vortex flow and temperature distribution, the local heat transfer coefficients and the local flow losses are discussed for a sample case. For a Reynolds number of Re d = 1000 and a vortex generator angle of attack of β = 25 degrees heat transfer is enhanced locally by more than 300% and in the mean by 50%. These values increase further with Re and β

  10. Coronary heart disease index based on longitudinal electrocardiography

    Science.gov (United States)

    Townsend, J. C.; Cronin, J. P.

    1977-01-01

    A coronary heart disease index was developed from longitudinal ECG (LCG) tracings to serve as a cardiac health measure in studies of working and, essentially, asymptomatic populations, such as pilots and executives. For a given subject, the index consisted of a composite score based on the presence of LCG aberrations and weighted values previously assigned to them. The index was validated by correlating it with the known presence or absence of CHD as determined by a complete physical examination, including treadmill, resting ECG, and risk factor information. The validating sample consisted of 111 subjects drawn by a stratified-random procedure from 5000 available case histories. The CHD index was found to be significantly more valid as a sole indicator of CHD than the LCG without the use of the index. The index consistently produced higher validity coefficients in identifying CHD than did treadmill testing, resting ECG, or risk factor analysis.

  11. Parenting practices and school dropout: a longitudinal study.

    Science.gov (United States)

    Blondal, Kristjana S; Adalbjarnardottir, Sigrun

    2009-01-01

    Adolescents' perceptions of parenting style and parental involvement in their education were examined longitudinally and related to school dropout among Icelandic youth (N = 427). Results indicated that adolescents who, at age 14, characterized their parents as authoritative (showing acceptance and supervision) were more likely to have completed upper secondary school by age 22 than adolescents from non-authoritative families, controlling for adolescents' gender, socioeconomic status (SES), temperament, and parental involvement. Parenting style seems to more strongly predict school dropout than parental involvement. Further, parenting style may moderate the relationship between parental involvement and dropout, but not in all groups; only in authoritative families does parental involvement decrease the likelihood of school dropout. Furthermore, even after controlling for previous academic achievement, adolescents from authoritative families were less likely to drop out than adolescents from authoritarian and neglectful families. These findings emphasize the importance of encouraging quality parent-child relationships in order to reduce the likelihood of school dropout.

  12. Longitudinally mounted light emitting plasma in a dielectric resonator

    Energy Technology Data Exchange (ETDEWEB)

    Gilliard, Richard; DeVincentis, Marc; Hafidi, Abdeslam; O' Hare, Daniel; Hollingsworth, Gregg [LUXIM Corporation, 1171 Borregas Avenue, Sunnyvale, CA 94089 (United States)

    2011-06-08

    Methods for coupling power from a dielectric resonator to a light-emitting plasma have been previously described (Gilliard et al IEEE Trans. Plasma Sci. at press). Inevitably, regardless of the efficiency of power transfer, much of the emitted light is absorbed in the resonator itself which physically surrounds much if not all of the radiating material. An investigation into a method is presented here for efficiently coupling power to a longitudinally mounted plasma vessel which is mounted on the surface of the dielectric material of the resonator, thereby eliminating significant absorption of light within the resonator structure. The topology of the resonator and its physical properties as well as those of the metal halide plasma are presented. Results of basic models of the field configuration and plasma are shown as well as a configuration suitable as a practical light source.

  13. Generalized empirical likelihood methods for analyzing longitudinal data

    KAUST Repository

    Wang, S.

    2010-02-16

    Efficient estimation of parameters is a major objective in analyzing longitudinal data. We propose two generalized empirical likelihood based methods that take into consideration within-subject correlations. A nonparametric version of the Wilks theorem for the limiting distributions of the empirical likelihood ratios is derived. It is shown that one of the proposed methods is locally efficient among a class of within-subject variance-covariance matrices. A simulation study is conducted to investigate the finite sample properties of the proposed methods and compare them with the block empirical likelihood method by You et al. (2006) and the normal approximation with a correctly estimated variance-covariance. The results suggest that the proposed methods are generally more efficient than existing methods which ignore the correlation structure, and better in coverage compared to the normal approximation with correctly specified within-subject correlation. An application illustrating our methods and supporting the simulation study results is also presented.

  14. Cancer and autoimmunity: Harnessing longitudinal cohorts to probe the link.

    Science.gov (United States)

    Egiziano, Giordano; Bernatsky, Sasha; Shah, Ami A

    2016-02-01

    In many autoimmune rheumatic diseases, there is an increased risk of cancer compared to the general population. While reasons for this increased risk have not been elucidated, it has been hypothesized that the link between cancer and autoimmunity may be bidirectional. For instance, chronic inflammation and damage from the rheumatic disease or its therapies may trigger malignant transformation; conversely, antitumor immune responses targeting cancers may become cross-reactive resulting in autoimmunity. In rare rheumatic diseases, longitudinal observational studies can play a critical role in studying these complex relationships, thereby enabling investigators to quantify the extent of cancer risk, identify unique clinical phenotypes associated with cancer, investigate the biological link between these conditions, and define optimal strategies for screening and treatment of the underlying cancer. In this review, we discuss recent data on cancer in the rheumatic diseases and suggest a research agenda to address several gaps in our current knowledge base. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Longitudinal study of spatial working memory development in young children.

    Science.gov (United States)

    Tsujii, Takeo; Yamamoto, Eriko; Masuda, Sayako; Watanabe, Shigeru

    2009-05-27

    This study longitudinally compared activity in the frontal cortex during a spatial working memory task between 5-year-old and 7-year-old children using near-infrared spectroscopy. Eight children participated in this study twice, once at 5 years and once at 7 years of age. Behavioral analysis showed that older children performed the working memory task more precisely and more rapidly than younger children. Near-infrared spectroscopy analysis showed that right hemisphere dominance was observed in older children, whereas no hemispheric difference was apparent in younger children. Children with strengthened lateralization showed improved performance from 5 to 7 years. We therefore offer the first demonstration of the developmental changes in frontal cortical activation during spatial working memory tasks during the preschool period.

  16. Longitudinal and transverse quasielastic response functions of light nuclei

    International Nuclear Information System (INIS)

    Carlson, J.; Jourdan, J.; Sick, I.; Schiavilla, R.

    2002-01-01

    The 3 He and 4 He longitudinal and transverse response functions are determined from an analysis of the world data on quasielastic inclusive electron scattering. The corresponding Euclidean response functions are derived and compared to those calculated with Green's function Monte Carlo methods, using realistic interactions and currents. Large contributions associated with two-body currents are found, particularly in the 4 He transverse response, in agreement with data. The contributions of the two-body charge and current operators in the 3 He, 4 He, and 6 Li response functions are also studied via sum-rule techniques. A semiquantitative explanation for the observed systematics in the excess of transverse quasielastic strength, as function of mass number and momentum transfer, is provided. Finally, a number of model studies with simplified interactions, currents, and wave functions are carried out to elucidate the role played, in the full calculation, by tensor interactions and correlations

  17. A Longitudinal Study on Human Outdoor Decomposition in Central Texas.

    Science.gov (United States)

    Suckling, Joanna K; Spradley, M Katherine; Godde, Kanya

    2016-01-01

    The development of a methodology that estimates the postmortem interval (PMI) from stages of decomposition is a goal for which forensic practitioners strive. A proposed equation (Megyesi et al. 2005) that utilizes total body score (TBS) and accumulated degree days (ADD) was tested using longitudinal data collected from human remains donated to the Forensic Anthropology Research Facility (FARF) at Texas State University-San Marcos. Exact binomial tests examined the rate of the equation to successfully predict ADD. Statistically significant differences were found between ADD estimated by the equation and the observed value for decomposition stage. Differences remained significant after carnivore scavenged donations were removed from analysis. Low success rates for the equation to predict ADD from TBS and the wide standard errors demonstrate the need to re-evaluate the use of this equation and methodology for PMI estimation in different environments; rather, multivariate methods and equations should be derived that are environmentally specific. © 2015 American Academy of Forensic Sciences.

  18. Longitudinal instability of an induction linac with acceleration

    International Nuclear Information System (INIS)

    Smith, L.; Lee, E.P.

    1993-05-01

    The question arises as to what effect acceleration, which so far has been ignored, has on the longitudinal instability of an induction linac. The answer is not much for the anticipated acceleration rate (1--2 MeV/m) and minimum e-folding distance for the instability (50--500 meters). However, total unstable growth is significantly reduced over distances which are long enough for appreciable acceleration to occur. The purpose of this note is to record a calculation of the instability, including a constant acceleration rate. Some interesting features emerge -- for example, the velocity of the head is a more convenient independent variable than axial position and, for an initial sinusoidal perturbation of velocity in time, the number of oscillations along the pulse is constant; as the pulse shortens in nine the frequency increases

  19. Longitudinal Target-Spin Asymmetries for Deeply Virtual Compton Scattering

    Science.gov (United States)

    Seder, E.; Biselli, A.; Pisano, S.; Niccolai, S.; Smith, G. D.; Joo, K.; Adhikari, K.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Battaglieri, M.; Bedlinskiy, I.; Bono, J.; Boiarinov, S.; Bosted, P.; Briscoe, W.; Brock, J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Carlin, C.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crabb, D.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hirlinger Saylor, N.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joosten, S.; Keith, C. D.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Meekins, D. G.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Munoz Camacho, C.; Nadel-Turonski, P.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L. L.; Park, K.; Park, S.; Pasyuk, E.; Peng, P.; Phelps, W.; Pogorelko, O.; Price, J. W.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Senderovich, I.; Simonyan, A.; Skorodumina, I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tang, W.; Tian, Y.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.; CLAS Collaboration

    2015-01-01

    A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for e p →e'p'γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2 , xB, t , and ϕ , for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

  20. Longitudinal and transverse digital image reconstruction with a tomographic scanner

    International Nuclear Information System (INIS)

    Pickens, D.R.; Price, R.R.; Erickson, J.J.; Patton, J.A.; Partain, C.L.; Rollo, F.D.

    1981-01-01

    A Siemens Gammasonics PHO/CON-192 Multiplane Imager is interfaced to a digital computer for the purpose of performing tomographic reconstructions from the data collected during a single scan. Data from the two moving gamma cameras as well as camera position information are sent to the computer by an interface designed in the authors' laboratory. Backprojection reconstruction is implemented by the computer. Longitudinal images in whole-body format as well as smaller formats are reconstructed for up to six planes simultaneously from the list mode data. Transverse reconstructions are demonstrated for 201 T1 myocardial scans. Post-reconstruction deconvolution processing to remove the blur artifact (characteristic of focal plane tomography) is applied to a multiplane phantom. Digital data acquisition of data and reconstruction of images are practical, and can extend the usefulness of the machine when compared with the film output (author)

  1. [Autoaggression and pulse rate--a longitudinal study].

    Science.gov (United States)

    Rohmann, U H; Elbing, U; Hartmann, H

    1988-12-01

    This article presents a model of autoaggressive behavior in which a distinction is made between determining and maintaining factors. Specific environmental, in particular social, and organismic variables are linked to them. The two types of variables interact, thus causing or maintaining autoaggressive behavior. A theory of autoaggression must therefore rely on multicausal/multimodal explanations. A connection between autoaggression and a high level of arousal suggests itself. In this single-case longitudinal study a comparison was made between heart rate and frequency of autoaggressive behavior. High heart rates were found to be correlated with low frequencies of autoaggressive behavior and vice versa. Decreasing autoaggressive behavior was coupled with increasing muscle relaxation and increasing motor activity. However, abnormally high heart rates were associated with both low and high levels of motor activity.

  2. TWITCH PARAMETERS IN TRANSVERSAL AND LONGITUDINAL BICEPS BRACHII RESPONSE

    Directory of Open Access Journals (Sweden)

    Boštjan Šimunič

    2010-01-01

    Full Text Available Assessment of the contractile properties of skeletal muscles is continuing to be an important issue and a difficult task methodologically. Longitudinal direction of skeletal muscle contraction blurs intrinsic muscle belly contractile properties with many factors. This study evaluates and explains contractile properties such as: delay time (Td, contraction time (Tc, half relaxation time (Tr and maximal amplitude (Dm extracted from twitch transversal response and compare them with torque response. In fifteen healthy males (age 23.7 ± 3.4 years isometric twitch transversal and torque responses were simultaneously recorded during graded electrically elicited contractions in the biceps brachii muscle. The amplitude of electrical stimulation was increased in 5 mA steps from a threshold up to a maximal response. The muscles’ belly transversal response was measured by a high precision mechanical displacement sensor while elbow joint torque was calculated from force readings. Results indicate a parabolic relation between the transversal displacement and the torque Dm. A significantly shorter Tc was found in transversal response without being correlated to torque Tc (r = -0.12; > 0.05. A significant correlation was found between torque Tc and the time occurrence of the second peak in the transversal response (r = 0.83; < 0.001. Electrical stimulation amplitude dependant variation of the Tc was notably different in transversal than in torque response. Td was similar at submaximal and maximal responses but larger in transversal at just above threshold contractions. Tr has a similar linear trend in both responses, however, the magnitude and the slope are much larger in the transversal response. We could conclude that different mechanisms affect longitudinal and transversal twitch skeletal muscle deformations. Contractile properties extracted from the transversal response enable alternative insights into skeletal muscle contraction mechanics.

  3. Deeply virtual Compton scattering off longitudinally polarised protons at HERMES

    Energy Technology Data Exchange (ETDEWEB)

    Mahon, David Francis

    2010-06-15

    This thesis details the simultaneous extraction of three polarisation-dependent asymmetries in the distribution of real photons from the ep{yields}ep{gamma} interaction and its indistinguishable deeply virtual Compton scattering and Bethe-Heitler processes at the HERMES fixed-target experiment at Desy. The data analysed were taken using a longitudinally polarised 27.57 GeV positron beam incident on a longitudinally polarised hydrogen gas target. The extracted asymmetries include two single-spin asymmetries A{sub UL} and A{sub LU} which depend on the polarisation of the target and beam respectively, averaged over all other polarisation states. The double-spin asymmetry A{sub LL} dependent on the product of the beam and target polarisations is extracted for the first time. The asymmetry amplitudes extracted relate to combinations of Generalised Parton Distributions (GPDs), predominantly H and H. The extracted amplitudes are presented across the HERMES kinematic range alongside theoretical predictions from a GPD model based on double distributions. Large sin {phi} and cos(0{phi}) amplitudes are observed for A{sub UL} and A{sub LL} respectively, with an unexpectedly large sin(2{phi}) amplitude for A{sub UL}. The results for the A{sub UL} and A{sub LL} asymmetries are broadly compatible with theory predictions, and the extracted A{sub LU} amplitudes are compatible with HERMES results extracted from a significantly larger data set. It is foreseen that these results will form input to future global data-based GPD models which aim to provide a better understanding of GPDs. (orig.)

  4. Parent and Child Cigarette Use: A Longitudinal, Multigenerational Study

    Science.gov (United States)

    Staff, Jeremy

    2013-01-01

    OBJECTIVES: Using longitudinal data from the multigenerational Youth Development Study (YDS), this article documents how parents’ long-term smoking trajectories are associated with adolescent children’s likelihood of smoking. Prospective data from the parents (from age 14–38 years) enable unique comparisons of the parents’ and children’s smoking behavior, as well as that of siblings. METHODS: Smoking trajectories are constructed using latent class analysis for the original YDS cohort (n = 1010). Multigenerational longitudinal data from 214 parents and 314 offspring ages 11 years and older are then analyzed by using logistic regression with cluster-corrected SEs. RESULTS: Four latent smoking trajectories emerged among the original cohort: stable nonsmokers (54%), early-onset light smokers who quit/reduce (16%), late-onset persistent smokers (14%), and early-onset persistent heavy smokers (16%). Although 8% of children of stable nonsmokers smoked in the last year, the other groups’ children had much higher percentages, ranging from 23% to 29%. Multivariate logistic regression models confirm that these significant differences were robust to the inclusion of myriad child- and parent-level measures (for which child age and grade point average [GPA] are significant predictors). Older sibling smoking, however, mediated the link between parental heavy smoking and child smoking. CONCLUSIONS: Even in an era of declining rates of teenage cigarette use in the United States, children of current and former smokers face an elevated risk of smoking. Prevention efforts to weaken intergenerational associations should consider parents’ long-term cigarette use, as well as the smoking behavior of older siblings in the household. PMID:23918887

  5. Longitudinal study of body composition in spinal cord injury patients

    Directory of Open Access Journals (Sweden)

    Roop Singh

    2014-01-01

    Full Text Available Background: Bone mass loss and muscle atrophy are the frequent complications occurring after spinal cord injury (SCI. The potential risks involved with these changes in the body composition have implications for the health of the SCI individual. Thus, there is a need to quantitate and monitor body composition changes accurately in an individual with SCI. Very few longitudinal studies have been reported in the literature to assess body composition and most include relatively small number of patients. The present prospective study aimed to evaluate the body composition changes longitudinally by DEXA in patients with acute SCI. Materials and Methods: Ninety five patients with acute SCI with neurological deficits were evaluated for bone mineral content (BMC, body composition [lean body mass (LBM and fat mass] by dual-energy X-ray absorptiometry during the first year of SCI. Results: There was a significant decrease in BMC ( P < 0.05 and LBM ( P < 0.05 and increase in total body fat mass (TBFM and percentage fat at infra-lesional sites. The average decrease was 14.5% in BMC in lower extremities, 20.5% loss of LBM in legs and 15.1% loss of LBM in trunk, and increase of 0.2% in fat mass in legs and 17.3% increased fat in the lower limbs at 1 year. The tetraplegic patients had significant decrease in arm BMC ( P < 0.001, arm LBM ( P < 0.01 and fat percentage ( P < 0.01 compared to paraplegics. Patients with complete motor injury had higher values of TBFM and fat percentage, but comparable values of BMC and LBM to patients with incomplete motor injury. Conclusions: Our findings suggest that there is a marked decrease in BMC and LBM with increase in adiposity during the first year of SCI. Although these changes depend on the level and initial severity of lesions, they are also influenced by the neurological recovery after SCI.

  6. The longitudinal impact of depression on disability in Parkinson disease.

    Science.gov (United States)

    Pontone, Gregory M; Bakker, Catherine C; Chen, Shaojie; Mari, Zoltan; Marsh, Laura; Rabins, Peter V; Williams, James R; Bassett, Susan S

    2016-05-01

    Depression in Parkinson disease (PD) is a common problem that worsens quality of life and causes disability. However, little is known about the longitudinal impact of depression on disability in PD. This study examined the association between disability and DSM-IV-TR depression status across six years. Longitudinal cohort study with assessments at study entry, year two, four, and six conducted in the Morris K. Udall Parkinson Disease Research Center. Recruitment totaled 137 adult men and women with idiopathic PD in which up to six years of data on demographic, motor, and non-motor variables was collected. Movement disorder specialists used the structured interview for DSM-IV-TR depressive disorders and the Northwestern Disability Scale to assess depression and disability. A generalized linear mixed model was fitted with Northwestern Disability Scale score as the dependent variable to determine the effect of baseline depression status on disability. A total of 43 participants were depressed at baseline compared to 94 without depression. Depressed participants were more likely to be female, were less educated, were less likely to take dopamine agonists, and more likely to have motor fluctuations. Controlling for these variables, symptomatic depression predicted greater disability compared to both never depressed (p = 0.0133) and remitted depression (p = 0.0009). Disability associated with symptomatic depression at baseline was greater over the entire six-year period compared to participants with remitted depressive episodes or who were never depressed. Persisting depression is associated with a long-term adverse impact on daily functioning in PD. Adequate treatment or spontaneous remission of depression improves ADL function. Copyright © 2015 John Wiley & Sons, Ltd.

  7. Actively adjustable step-type ultrasonic horns in longitudinal vibration

    Science.gov (United States)

    Lin, Shuyu; Guo, Hao; Xu, Jie

    2018-04-01

    Actively adjustable longitudinal step-type ultrasonic horns are proposed and studied. The horn is composed of a traditional ultrasonic horn and piezoelectric material. In practical applications, this kind of step-type ultrasonic horn is mechanically excited by an ultrasonic transducer and the piezoelectric material is connected to an adjustable electric impedance. In this research, the effects of the electric impedance and of the location of the piezoelectric material on the performance of the horn are studied. It is shown that when the electric resistance is increased, the resonance frequency of the horn is increased; the displacement magnification is increased when the piezoelectric material is located in the large end and decreased when the piezoelectric material is located in the small end of the horn. The displacement magnification for the piezoelectric material in the large end is larger than that for the piezoelectric material in the small end of the horn. Some step-type ultrasonic horns are designed and manufactured; the resonance frequency and the displacement magnification are measured by means of POLYTEC Laser Scanning vibrometer. It is shown that the theoretical resonance frequency and the displacement magnification are in good agreement with the measured results. It is concluded that by means of the insertion of the piezoelectric material in the longitudinal horn, the horn performance can be adjusted by changing the electric impedance and the location of the piezoelectric material in the horn. It is expected that this kind of adjustable ultrasonic horns can be used in traditional and potential ultrasonic technologies where the vibrational performance adjustment is needed.

  8. Longitudinal Associations between Physical Activity and Educational Outcomes.

    Science.gov (United States)

    Kari, Jaana T; Pehkonen, Jaakko; Hutri-Kähönen, Nina; Raitakari, Olli T; Tammelin, Tuija H

    2017-11-01

    This longitudinal study examined the role of leisure-time physical activity in academic achievement at the end of compulsory basic education and educational attainment in adulthood. The data were drawn from the ongoing longitudinal Cardiovascular Risk in Young Finns Study, which was combined with register-based data from Statistics Finland. The study consisted of children who were 12 yr (n = 1723, 49% boys) and 15 yr (n = 2445, 48% boys) of age at the time when physical activity was measured. The children were followed up until 2010, when their mean age was 40 yr. Physical activity was self-reported and included several measurements: overall leisure-time physical activity outside school hours, participation in sports club training sessions, and participation in sports competitions. Individuals' educational outcomes were measured with the self-reported grade point average at age 15 yr and register-based information on the years of completed postcompulsory education in adulthood. Ordinary least squares models and the instrumental variable approach were used to analyze the relationship between physical activity and educational outcomes. Physical activity in adolescence was positively associated with educational outcomes. Both the physical activity level at age 15 yr and an increase in the physical activity level between the ages of 12 and 15 yr were positively related to the grade point average at age 15 yr and the years of postcompulsory education in adulthood. The results were robust to the inclusion of several individual and family background factors, including health endowments, family income, and parents' education. The results provide evidence that physical activity in adolescence may not only predict academic success during compulsory basic education but also boost educational outcomes later in life.

  9. Design of the APS transverse and longitudinal damping system

    International Nuclear Information System (INIS)

    Sellyey, W.; Barr, D.; Kahana, E.; Votaw, A.

    1994-01-01

    The main sources of instabilities in the Advanced Photon Source (APS) storage ring are expected to be higher-order modes (HOMs) of the accelerating cavities and the resistive wall impedance of the small insertion devices beam tubes. Extensive efforts are being made to reduce the Qs of HOMs. The maximum operating current of the ring will be 300 mA. At this current, analysis of measurements on cavity prototypes shows that the transverse growth rates will be less than 500/sec above radiation damping. The longitudinal growth rate due to HOMs is predicted to never exceed the radiation damping of 213/sec. The largest transverse resistive wall growth rate is calculated to be 2720/sec when 54 evenly spaced rigid bunches are used to produce 300 mA. There will be 26 additional unstable modes. The sum of these growth rates is 17,163/sec. Thus, it is clear that an effective transverse damping system will be needed and that the strength of this damper will be dominated by the resistive wall modes. A longitudinal damper system will also be built. This will provide damping about 2/3 times that due to synchrotron radiation. The most serious disturbances which can initiate instabilities will take place at injection. Typically, each bunch in the ring will be accumulated by injecting 115 of the final charge five times. A standard mode of operation is used in this paper in which there will be 54 evenly spaced bunches around the ring. During the ring filling process, the highest growth rates will occur when the last fifth of a bunch is injected into the last bunch. The largest expected vertical excursion of 1/5 of a bunch is about 5 mm. Anything larger will cause the bunch to scrape in the insertion device sections

  10. Child adiposity and maternal feeding practices: a longitudinal analysis.

    Science.gov (United States)

    Webber, Laura; Cooke, Lucy; Hill, Claire; Wardle, Jane

    2010-12-01

    Parental control has been hypothesized to cause weight gain in children by weakening self-regulatory processes. However, most studies that link control with weight have been cross-sectional, and therefore causation is uncertain. It remains possible that parental control is a response to child overweight rather than a cause. We investigated the direction of the association between parental feeding practices and children's adiposity in a longitudinal study. Three subscales of the Child Feeding Questionnaire (CFQ) that measure "pressure," "restriction," and "monitoring" were completed by 213 mothers of 7-9-y-old children as part of the Physical Exercise and Appetite in CHildren Study (PEACHES) and repeated by 113 mothers 3 y later. Baseline and follow-up anthropometric measurements [body mass index (BMI); fat mass index (FMI), and waist circumference (WC)] were made by researchers when the children were aged 7-9 y and 10-11 y. Regression analyses showed no association between any of the CFQ scales at baseline and change in child adiposity. In contrast, higher child BMI at baseline predicted a smaller decrease in follow-up CFQ "monitoring" (P = 0.003) and a larger decrease in "pressure to eat" (P = 0.04) after baseline scores were controlled for. Similar results were observed for FMI and WC, although they did not reach significance for WC. There were no significant longitudinal associations between child adiposity and the CFQ "restriction" subscale. The results were more consistent with a "child-responsive" model whereby a mother's choice of feeding practice is influenced by her child's weight status rather than her feeding practices influencing the child's weight gain.

  11. Birth order and paediatric allergic disease: A nationwide longitudinal survey.

    Science.gov (United States)

    Kikkawa, T; Yorifuji, T; Fujii, Y; Yashiro, M; Okada, A; Ikeda, M; Doi, H; Tsukahara, H

    2018-05-01

    Environmental factors seem to be related to the incidence of allergic disease. Children with a later birth order are often exposed to environments, where pathogens and endotoxins can be found, and thus have a higher risk of developing infectious diseases. Therefore, birth order is regarded as an indicator that reflects post-natal environment. However, longitudinal studies are limited on this subject. This study sought to elucidate the relationships between birth order and allergic disease. From a nationwide longitudinal study that followed children born in 2001 (n = 47 015), we selected doctors' visits for 3 types of allergic disease-bronchial asthma, food allergy and atopic dermatitis-from infancy to 12 years of age and conducted binomial log-linear regression analysis to evaluate the associations between birth order and these diseases. We adjusted for the child and parental factors and estimated risk ratio (RR) and 95% confidence interval (CI) for each outcome. The associations between birth order and bronchial asthma were diverse; later birth order increased the risk in early childhood, but decreased the risks during school age. For example, the adjusted RR comparing third-born or higher and first-born children was 1.19 (95% CI, 1.05-1.35) between 30 and 42 months of age, but was 0.76 (95% CI, 0.65-0.89) between 10 and 11 years. Later birth order was generally protective for food allergy but increased the risk of atopic dermatitis. The influence of birth order depended on the type of allergic disease and the childhood period. Childhood is unique in terms of physical and immunological development, and the immune response to the post-natal environment in childhood appears to be heterogeneous. © 2018 John Wiley & Sons Ltd.

  12. Determinants of exercise among children. II. A longitudinal analysis.

    Science.gov (United States)

    DiLorenzo, T M; Stucky-Ropp, R C; Vander Wal, J S; Gotham, H J

    1998-01-01

    Research has demonstrated that physical activity serves an important preventive function against the development of cardiovascular disease. The recognition that U.S. children are often sedentary, coupled with the observation that physical activity habits tend to persist into adulthood, has prompted the investigation of exercise determinants consistent with social learning theory. The purposes of the present study were to identify social learning variables relevant to children's exercise and to explore the longitudinal predictive value of the determinants. Data were collected from 111 families (N = 54 girls, N = 57 boys) who were interviewed in both Phase 1 (fifth and sixth grades) and Phase 2 (eight and ninth grades) of this study. Data from mothers (N = 111) were collected during both phases; data from 80 fathers were collected at Phase 2 only. The results of simultaneous stepwise regression analyses indicated that child's enjoyment of physical activity was the only consistent predictor of physical activity during Phase 1. At Phase 2, child's exercise knowledge, mother's physical activity, and child's and mother's friend modeling/support emerged as predictors for girls. For boys, child's self-efficacy for physical activity, exercise knowledge, parental modeling, and interest in sports media were important. Longitudinally, mother's self-efficacy, barriers to exercise, enjoyment of physical activity, and child's self-efficacy for physical activity were important for girls. Only child's exercise knowledge predicted boys' physical activity. The addition of information from fathers nearly doubled the explanatory power of the predictors for both genders. Socialization in the family unit exerts a tremendous influence on health-related behaviors such as exercise. The relative importance of determinants seems to differ for girls and boys and the pattern of these determinants appears to change over time.

  13. Longitudinal evaluation of bronchopulmonary disease in children with cystic fibrosis.

    Science.gov (United States)

    Farrell, Philip M; Li, Zhanhai; Kosorok, Michael R; Laxova, Anita; Green, Christopher G; Collins, Jannette; Lai, Hui-Chuan; Makholm, Linda M; Rock, Michael J; Splaingard, Mark L

    2003-09-01

    Children with cystic fibrosis (CF) develop bronchopulmonary disease at variable ages. Determining the epidemiology of chronic lung disease and quantifying its severity, however, have been difficult in infants and young children. As part of the Wisconsin CF Neonatal Screening Project, we were presented with an ideal opportunity to assess longitudinally the evolution of symptoms, signs, and quantitative measures of CF respiratory disease. After newborn screening test results led to early recognition, 64 patients diagnosed at a median age of 6.71 weeks were enrolled and studied systematically at a median age of 11.3 years to obtain clinical information, chest radiographs, and pulmonary function tests. Our observations revealed that a frequent cough by history is evident by 10.5 months of age in half the patients. Quantitative chest radiology (CXR scoring) demonstrated that potentially irreversible abnormalities are present in half the children by 2 years. The severity of Wisconsin and Brasfield CXR scores increased in association with respiratory infections. Longitudinal progression of Wisconsin CXR scores was related to age (P < 0.001), pancreatic insufficiency (P = 0.005), and respiratory secretion cultures positive for Staphylococus aureas (P = 0.039). In contrast, serial spirometry showed limited sensitivity, as did lung volume determinations; neither was satisfactory as repeated measures with acceptable quality control until after 7 years of age. Time to event analyses revealed that half the patients had % predicted FEF(25-75) and FEV(1)/FVC values greater than 80% until 10.7 and 9.9 years, respectively. We conclude that of the methods evaluated, quantitative chest radiology is currently the best procedure for frequent assessment of bronchopulmonary disease in CF, and that radiographic progression is evident in approximately 85% of patients by 5 years of age. Our results also suggest that bronchiectasis and other radiographic evidence of chronic infection are

  14. Longitudinal Model Predicting Self-Concept in Pediatric Chronic Illness.

    Science.gov (United States)

    Emerson, Natacha D; Morrell, Holly E R; Neece, Cameron; Tapanes, Daniel; Distelberg, Brian

    2018-04-16

    Although self-concept has been identified as salient to the psychosocial adjustment of adolescents dealing with a chronic illness (CI), little research has focused on its predictors it. Given that depression and parent-child attachment have been linked to self-concept in the population at large, the goal of this study was to evaluate these relationships longitudinally in a sample of adolescents with CI. Using participant data from the Mastering Each New Direction (MEND) program, a 3-month psychosocial, family based intensive outpatient program for adolescents with CI, we employed multilevel modeling to test longitudinal changes in self-concept, as predicted by depressive symptoms and parent-child attachment, in a sample of 50 youths (M age  = 14.56, SD age  = 1.82) participating in MEND. Both "time spent in the program" and decreases in depressive symptoms were associated with increases in self-concept over time. Higher baseline levels of avoidant attachment to both mother and father were also associated with greater initial levels of self-concept. Targeting depressive symptoms and supporting adaptive changes in attachment may be key to promoting a healthy self-concept in pediatric CI populations. The association between avoidant attachment and higher baseline self-concept scores may reflect differences in participants' autonomy, self-confidence, or depression. Limitations of the study include variability in the amount of time spent in the program, attrition in final time point measures, and the inability to fully examine and model all potential covariates due to a small sample size (e.g. power). © 2018 Family Process Institute.

  15. Gastrocnemius muscle contracture after spinal cord injury: a longitudinal study.

    Science.gov (United States)

    Diong, Joanna; Harvey, Lisa A; Kwah, Li Khim; Clarke, Jillian L; Bilston, Lynne E; Gandevia, Simon C; Herbert, Robert D

    2013-07-01

    The aim of this study was to examine changes in passive length and stiffness of the gastrocnemius muscle-tendon unit in people after spinal cord injury. In a prospective longitudinal study, eight wheelchair-dependent participants with severe paralysis were assessed 3 and 12 mos after spinal cord injury. Passive torque-angle data were obtained as the ankle was slowly rotated through range at six knee angles. Differences in passive ankle torque-angle data recorded at different knee angles were used to derive passive length-tension curves of the gastrocnemius muscle-tendon unit. Ultrasound imaging was used to determine fascicle and tendon contributions to the muscle-tendon unit length-tension curves. The participants had ankle contractures (mean [SD] maximum passive ankle dorsiflexion angle, 88 [9] degrees) 3 mos after spinal cord injury. Ankle range did not worsen significantly during the subsequent 9 mos (mean change, -5 degrees; 95% confidence interval, -16 to 6 degrees). There were no changes in the mean slack length or the stiffness of the gastrocnemius muscle-tendon unit or in the slack lengths of the fascicles or the tendon between 3 and 12 mos after spinal cord injury. There were no consistent patterns of the change in slack length or stiffness with the changes in ankle range in the data from the individual participants. This study, the first longitudinal study of muscle length and stiffness after spinal cord injury, showed that the length and the stiffness of the gastrocnemius did not change substantially between 3 and 12 mos after injury.

  16. Longitudinal Variations in the Variability of Spread F Occurrence

    Science.gov (United States)

    Groves, K. M.; Bridgwood, C.; Carrano, C. S.

    2017-12-01

    The complex dynamics of the equatorial ionosphere have attracted the interest and attention of researchers for many decades. The relatively local processes that give rise to large meridional gradients have been well documented and the associated terminology has entered the common lexicon of ionospheric research (e.g., fountain effect, equatorial anomaly, bubbles, Spread F). Zonal variations have also been noted, principally at the level of determining longitudinal differences in seasonal activity patterns. Due to a historical lack of high resolution ground-based observations at low latitudes, the primary source of data for such analyses has been space-based observations from satellites such as ROCSAT, DMSP, C/NOFS that measure in situ electron density variations. An important longitudinal variation in electron density structure associated with non-migrating diurnal tides was discovered by Immel et al. in 2006 using data from the FUV sensor aboard the NASA IMAGE satellite. These satellite observations have been very helpful in identifying the structural characteristics of the equatorial ionosphere and the occurrence of Spread F, but they provide little insight into variations in scintillation features and potential differences in bubble development characteristics. Moreover space-based studies tend towards the statistics of occurrence frequency over periods of weeks to months. A recent analysis of daily spread F occurrence as determined by low latitude VHF scintillation activity shows that statistical results that are consistent with previous space-based observations, but the level of variability in the occurrence data show marked variations with longitude. For example, the American sector shows very low in-season variability while the African and Asian sectors exhibit true day-to-day variability regardless of seasonal variations. The results have significant implications for space weather as they suggest that long-term forecasts of equatorial scintillation may be

  17. Bullying as a longitudinal predictor of adolescent dating violence.

    Science.gov (United States)

    Foshee, Vangie A; McNaughton Reyes, Heath Luz; Vivolo-Kantor, Alana M; Basile, Kathleen C; Chang, Ling-Yin; Faris, Robert; Ennett, Susan T

    2014-09-01

    One suggested approach to preventing adolescent dating violence is to prevent behavioral precursors to dating violence, such as bullying. However, no longitudinal study has examined bullying as a behavioral precursor to dating violence. In this study, longitudinal data were used to examine (1) whether direct and indirect bullying perpetration in the sixth grade predicted the onset of physical dating violence perpetration by the eighth grade and (2) whether the associations varied by sex and race/ethnicity of the adolescent. Data were collected in school from sixth graders in three primarily rural counties and then again when students were in the eighth grade. Analyses were conducted with 1,154 adolescents who had not perpetrated dating violence at the sixth-grade assessment. The sample was 47% male, 29% black, and 10% of another race/ethnicity than black or white. Direct bullying, defined as hitting, slapping, or picking on another kid in the sixth grade, predicted the onset of physical dating violence perpetration by the eighth grade, controlling for indirect bullying and potential confounders. Although indirect bullying, defined as spreading false rumors and excluding students from friendship groups, was associated with the onset of physical dating violence perpetration in bivariate analyses, it did not predict the onset of physical dating violence when controlling for direct bullying. None of the associations examined varied by sex or race/ethnicity of the adolescents. Our findings suggest that efforts targeted at preventing direct bullying may also prevent the onset of physical dating violence. Copyright © 2014 Society for Adolescent Health and Medicine. All rights reserved.

  18. Longitudinal relations between constructive and destructive conflict and couples' sleep.

    Science.gov (United States)

    El-Sheikh, Mona; Kelly, Ryan J; Koss, Kalsea J; Rauer, Amy J

    2015-06-01

    We examined longitudinal relations between interpartner constructive (negotiation) and destructive (psychological and physical aggression) conflict strategies and couples' sleep over 1 year. Toward explicating processes of effects, we assessed the intervening role of internalizing symptoms in associations between conflict tactics and couples' sleep. Participants were 135 cohabiting couples (M age = 37 years for women and 39 years for men). The sample included a large representation of couples exposed to economic adversity. Further, 68% were European American and the remainder were primarily African American. At Time 1 (T1), couples reported on their conflict and their mental health (depression, anxiety). At T1 and Time 2, sleep was examined objectively with actigraphs for 7 nights. Three sleep parameters were derived: efficiency, minutes, and latency. Actor-partner interdependence models indicated that husbands' use of constructive conflict forecasted increases in their own sleep efficiency as well as their own and their wives' sleep duration over time. Actor and partner effects emerged, and husbands' and wives' use of destructive conflict strategies generally predicted worsening of some sleep parameters over time. Several mediation and intervening effects were observed for destructive conflict strategies. Some of these relations reveal that destructive conflict is associated with internalizing symptoms, which in turn are associated with some sleep parameters longitudinally. These findings build on a small, albeit growing, literature linking sleep with marital functioning, and illustrate that consideration of relationship processes including constructive conflict holds promise for gaining a better understanding of factors that influence the sleep of men and women. (c) 2015 APA, all rights reserved).

  19. Nonlinear Longitudinal Mode Instability in Liquid Propellant Rocket Engine Preburners

    Science.gov (United States)

    Sims, J. D. (Technical Monitor); Flandro, Gary A.; Majdalani, Joseph; Sims, Joseph D.

    2004-01-01

    Nonlinear pressure oscillations have been observed in liquid propellant rocket instability preburner devices. Unlike the familiar transverse mode instabilities that characterize primary combustion chambers, these oscillations appear as longitudinal gas motions with frequencies that are typical of the chamber axial acoustic modes. In several respects, the phenomenon is similar to longitudinal mode combustion instability appearing in low-smoke solid propellant motors. An important feature is evidence of steep-fronted wave motions with very high amplitude. Clearly, gas motions of this type threaten the mechanical integrity of associated engine components and create unacceptably high vibration levels. This paper focuses on development of the analytical tools needed to predict, diagnose, and correct instabilities of this type. For this purpose, mechanisms that lead to steep-fronted, high-amplitude pressure waves are described in detail. It is shown that such gas motions are the outcome of the natural steepening process in which initially low amplitude standing acoustic waves grow into shock-like disturbances. The energy source that promotes this behavior is a combination of unsteady combustion energy release and interactions with the quasi-steady mean chamber flow. Since shock waves characterize the gas motions, detonation-like mechanisms may well control the unsteady combustion processes. When the energy gains exceed the losses (represented mainly by nozzle and viscous damping), the waves can rapidly grow to a finite amplitude limit cycle. Analytical tools are described that allow the prediction of the limit cycle amplitude and show the dependence of this wave amplitude on the system geometry and other design parameters. This information can be used to guide corrective procedures that mitigate or eliminate the oscillations.

  20. Bullying as a Longitudinal Predictor of Adolescent Dating Violence

    Science.gov (United States)

    Foshee, Vangie A.; Reyes, Heath Luz McNaughton; Vivolo-Kantor, Alana M.; Basile, Kathleen C.; Chang, Ling-Yin; Faris, Robert; Ennett, Susan T.

    2015-01-01

    Purpose One suggested approach to preventing adolescent dating violence is to prevent behavioral precursors to dating violence, such as bullying. However, no longitudinal study has examined bullying as a behavioral precursor to dating violence. In this study, longitudinal data were used to examine (1) whether direct and indirect bullying perpetration in the sixth grade predicted the onset of physical dating violence perpetration by the eighth grade and (2) whether the associations varied by sex and race/ethnicity of the adolescent. Methods Data were collected in school from sixth graders in three primarily rural counties and then again when students were in the eighth grade. Analyses were conducted with 1,154 adolescents who had not perpetrated dating violence at the sixth-grade assessment. The sample was 47% male, 29% black, and 10% of another race/ethnicity than black or white. Results Direct bullying, defined as hitting, slapping, or picking on another kid in the sixth grade, predicted the onset of physical dating violence perpetration by the eighth grade, controlling for indirect bullying and potential confounders. Although indirect bullying, defined as spreading false rumors and excluding students from friendship groups, was associated with the onset of physical dating violence perpetration in bivariate analyses, it did not predict the onset of physical dating violence when controlling for direct bullying. None of the associations examined varied by sex or race/ethnicity of the adolescents. Conclusions Our findings suggest that efforts targeted at preventing direct bullying may also prevent the onset of physical dating violence. PMID:24768162

  1. Research on conditional characteristics vision real-time detection system for conveyor belt longitudinal tear

    NARCIS (Netherlands)

    Qiao, Tiezhu; Li, Xinyu; Pang, Y.; Lü, Yuxiang; Wang, Feng; Jin, Baoquan

    2017-01-01

    Conveyor belt longitudinal tear is one of the most serious problems in coal mining. Existing systems cannot realise lossless and real-time detection for longitudinal tear of conveyor belt. Currently, visual detecting systems are proposed by many researchers and are becoming the future trend. A

  2. A Primer on Longitudinal Data Analysis in Education. Technical Report #1320

    Science.gov (United States)

    Nese, Joseph F. T.; Lai, Cheng-Fei; Anderson, Daniel

    2013-01-01

    Longitudinal data analysis in education is the study growth over time. A longitudinal study is one in which repeated observations of the same variables are recorded for the same individuals over a period of time. This type of research is known by many names (e.g., time series analysis or repeated measures design), each of which can imply subtle…

  3. Applying the Nominal Response Model within a Longitudinal Framework to Construct the Positive Family Relationships Scale

    Science.gov (United States)

    Preston, Kathleen Suzanne Johnson; Parral, Skye N.; Gottfried, Allen W.; Oliver, Pamella H.; Gottfried, Adele Eskeles; Ibrahim, Sirena M.; Delany, Danielle

    2015-01-01

    A psychometric analysis was conducted using the nominal response model under the item response theory framework to construct the Positive Family Relationships scale. Using data from the Fullerton Longitudinal Study, this scale was constructed within a long-term longitudinal framework spanning middle childhood through adolescence. Items tapping…

  4. Training, Innovation and Business Performance: An Analysis of the Business Longitudinal Survey.

    Science.gov (United States)

    Dockery, A. Michael

    This paper uses the Australian Bureau of Statistics' Business Longitudinal Survey to explore relationships between training, innovation, and firm performance for Australian businesses with less than 200 employees. The longitudinal nature of the data is used to test various hypotheses about the nature of the link between training, business changes,…

  5. The longitudinal relation between smoking and muscle strength in healthy adults

    NARCIS (Netherlands)

    Kok, Maarten O; Hoekstra, T.; Twisk, Jos W R

    2012-01-01

    AIM: To assess longitudinally whether smoking tobacco is related to muscle strength in healthy adults and to assess the influence of lifestyle covariates on this relation. METHODS: Data were obtained from the observational Amsterdam Growth and Health Longitudinal Study, with four repeated

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

    Science.gov (United States)

    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. Changes in HRM in Europe: A Longitudinal Comparative Study among 18 European Countries

    Science.gov (United States)

    Nikandrou, Irene; Apospori, Eleni; Papalexandris, Nancy

    2005-01-01

    Purpose: To examine HRM strategies and practices and HRM position within organizations in various cultural, economic and sociopolitical contexts from a longitudinal perspective. Design/methodology/approach: The study uses the 1995 and 1999 Cranet data in a longitudinal methodological framework to explore the changes and trends in 18 European…

  8. Longitudinal Predictors of Chinese Word Reading and Spelling among Elementary Grade Students

    Science.gov (United States)

    Yeung, Pui-Sze; Ho, Connie Suk-Han; Wong, Yau-Kai; Chung, Kevin Kien-Hoa; Lo, Lap-Yan

    2013-01-01

    The longitudinal predictive power of four important reading-related skills (phonological skills, rapid naming, orthographic skills, and morphological awareness) to Chinese word reading and writing to dictation (i.e., spelling) was examined in a 3-year longitudinal study among 251 Chinese elementary students. Rapid naming, orthographic skills, and…

  9. Role of the ambient magnetic field B in the longitudinal variation of ...

    African Journals Online (AJOL)

    Comparison of the longitudinal profile of B along the dip equator with average longitudinal profile of the zonal electric field Ey at the dip equator proves that on the average Ey is not independent of longitude as was assumed by earlier workers. It has been suggested that Joule heating of the atmosphere which depends on ...

  10. Longitudinal transport measurements in an energy recovery accelerator with triple bend achromat arcs

    Directory of Open Access Journals (Sweden)

    F. Jackson

    2016-12-01

    Full Text Available Longitudinal properties of electron bunches (energy spread and bunch length and their manipulation are of importance in free electron lasers (FELs, where magnetic bunch length compression is a common feature of beam transport. Recirculating accelerators and energy recovery linac accelerators (ERLs have been used as FEL drivers for several decades and control of longitudinal beam transport is particularly important in their magnet lattices. We report on measurements of longitudinal transport properties in an ERL-FEL, the ALICE (Accelerators and Lasers in Combined Experiments accelerator at Daresbury Laboratory. ALICE is an energy recovery research accelerator that drives an infrared free electron laser. By measuring the time of arrival of electron bunches, the canonical longitudinal transport quantities were measured in the beam transport and bunch compression sections of the lattice. ALICE includes a four-dipole bunch compression chicane providing fixed longitudinal transport, and triple bend achromat arcs including sextupole magnets where the first and second order longitudinal transport can be adjusted. The longitudinal transport properties in these lattice sections were measured and compared with the theoretical model of the lattice. A reasonable level of agreement has been found. The effect of sextupoles in second order, as well as first order, longitudinal correction is considered, with the measurements indicating the level of alignment of the beam to the center of the sextupole.

  11. The Longitudinal Joint Effect of Obesity and Major Depression on Work Performance Impairment

    NARCIS (Netherlands)

    Nigatu, Yeshambel T.; Reijneveld, Sijmen A.; Penninx, Brenda W. J. H.; Schoevers, Robert A.; Bultmann, Ute

    Objectives. We examined the longitudinal effect of obesity, major depression, and their combination on work performance impairment (WPI). Methods. We collected longitudinal data (2004-2013) on 1726 paid employees from the Netherlands Study of Depression and Anxiety at baseline and 2-, 4-, and 6-year

  12. Making meaning in the time of AIDS: longitudinal narratives from the ...

    African Journals Online (AJOL)

    Second, beyond what can be learned from the journals about individual and collective responses to AIDS, they suggest the value of longitudinal observational field studies as a method for understanding how cultural change occurs. And third, as an example of the potential of longitudinal field studies as a research method ...

  13. A ¤nonparametric dynamic additive regression model for longitudinal data

    DEFF Research Database (Denmark)

    Martinussen, T.; Scheike, T. H.

    2000-01-01

    dynamic linear models, estimating equations, least squares, longitudinal data, nonparametric methods, partly conditional mean models, time-varying-coefficient models......dynamic linear models, estimating equations, least squares, longitudinal data, nonparametric methods, partly conditional mean models, time-varying-coefficient models...

  14. Longitudinal Losses Due to Breathing Mode Excitation in Radiofrequency Linear Accelerators

    OpenAIRE

    Channell, Paul J.

    2010-01-01

    Transverse breathing mode oscillations in a particle beam can couple energy into longitudinal oscillations in a bunch of finite length and cause significant losses. We develop a model that illustrates this effect and explore the dependence on mismatch size, space-charge tune depression, longitudinal focusing strength, bunch length, and RF bucket length.

  15. The USA National Longitudinal Lesbian Family Study (NLLFS): homophobia, psychological adjustment, and protective factors

    NARCIS (Netherlands)

    Bos, H.M.W.; Gartrell, N.K.; Peyser, H.; van Balen, F.

    2008-01-01

    The study assessed the influence of protective factors on the psychological adjustment of children who had experienced homophobia and whose mothers were participants in a longitudinal study of planned lesbian families. Data were collected as part of the National Longitudinal Lesbian Family Study by

  16. The Longitudinal Interplay of Maternal Warmth and Adolescents' Self-Disclosure in Predicting Maternal Knowledge

    Science.gov (United States)

    Blodgett Salafia, Elizabeth H.; Gondoli, Dawn M.; Grundy, Amber M.

    2009-01-01

    This study examined the longitudinal associations among maternal warmth, adolescents' self-disclosure, and maternal knowledge during the transition to adolescence. Three years of self-report data were collected from 131 married mothers and their adolescents. Results from longitudinal analysis using adolescent reports indicated that greater…

  17. A Longitudinal Study of Children's Social Behaviors and Their Causal Relationship to Reading Growth

    Science.gov (United States)

    Lim, Hyo Jin; Kim, Junyeop

    2011-01-01

    This paper aims at investigating the causal effects of social behaviors on subsequent reading growth in elementary school, using the "Early Childhood Longitudinal Study-Kindergarten" ("ECLS-K") data. The sample was 8,869 subjects who provided longitudinal measures of reading IRT scores from kindergarten (1998-1999) to fifth…

  18. Prospective longitudinal evaluation of lung function during the first year of life after extracorporeal membrane oxygenation

    NARCIS (Netherlands)

    Hofhuis, W.; Hanekamp, M.N.; Ijsselstijn, H.; Nieuwhof, E.M.; Hop, W.C.J.; Tibboel, D.; Jongste, J.C. de; Merkus, P.J.F.M.

    2011-01-01

    OBJECTIVE: To collect longitudinal data on lung function in the first year of life after extracorporeal membrane oxygenation and to evaluate relationships between lung function and perinatal factors. Longitudinal data on lung function in the first year of life after extracorporeal membrane

  19. Factors contributing to the longitudinal development of social participation in individuals with cerebral palsy

    NARCIS (Netherlands)

    Tan, Siok Swan; van der Slot, Wilma M A; Ketelaar, Marjolijn; Becher, Jules G.; Dallmeijer, Annet J.; Smits, Dirk Wouter; Roebroeck, Marij E.

    2016-01-01

    Aims We aimed to determine factors associated with the longitudinal development of social participation in a Dutch population of individuals with Cerebral Palsy (CP) aged 1–24 years. Methods and procedures For this multicentre prospective longitudinal study, 424 individuals with CP aged 1–24 years

  20. Peer Influence and Nonsuicidal Self Injury: Longitudinal Results in Community and Clinically-Referred Adolescent Samples

    Science.gov (United States)

    Prinstein, Mitchell J.; Heilbron, Nicole; Guerry, John D.; Franklin, Joseph C.; Rancourt, Diana; Simon, Valerie; Spirito, Anthony

    2010-01-01

    Research suggests that adolescents' engagement in nonsuicidal self-injurious (NSSI) behaviors may be increasing over time, yet little is known regarding distal longitudinal factors that may promote engagement in these behaviors. Data from two longitudinal studies are presented to examine whether NSSI may be associated with peer influence…