Finite-amplitude strain waves in laser-excited plates.

PubMed

Mirzade, F Kh

2008-07-09

The governing equations for two-dimensional finite-amplitude longitudinal strain waves in isotropic laser-excited solid plates are derived. Geometric and weak material nonlinearities are included, and the interaction of longitudinal displacements with the field of concentration of non-equilibrium laser-generated atomic defects is taken into account. An asymptotic approach is used to show that the equations are reducible to the Kadomtsev-Petviashvili-Burgers nonlinear evolution equation for a longitudinal self-consistent strain field. It is shown that two-dimensional shock waves can propagate in plates.

Stress wave velocity patterns in the longitudinal-radial plane of trees for defect diagnosis

Treesearch

Guanghui Li; Xiang Weng; Xiaocheng Du; Xiping Wang; Hailin Feng

2016-01-01

Acoustic tomography for urban tree inspection typically uses stress wave data to reconstruct tomographic images for the trunk cross section using interpolation algorithm. This traditional technique does not take into account the stress wave velocity patterns along tree height. In this study, we proposed an analytical model for the wave velocity in the longitudinal–...

Equatorial Plasma Bubbles: Effect of Thermospheric Winds Modulated by DE3 Tidal Waves

NASA Astrophysics Data System (ADS)

Sidorova, L. N.; Filippov, S. V.

2018-03-01

A hypothesis about the effect of the tropospheric source on the longitudinal distributions of the equatorial plasma bubbles observed in the topside ionosphere was proposed earlier. It was supposed that this influence is transferred mainly by the thermospheric winds modulated by the DE3 tropospheric tidal waves. This conclusion was based on the discovered high degree correlation ( R ≅ 0.79) between the variations of the longitudinal distribution of the plasma bubbles and the neutral atmospheric density. In this work, the hypothesis of the effect of the thermospheric tidal waves on the plasma bubbles at the stage of their generation is subjected to further verification. With this purpose, the longitudinal distributions of the frequency of the plasma bubble observations at the different ionospheric altitudes ( 600 km, ROCSAT-1; 1100 km, ISS-b) are analyzed; their principal similarity is revealed. Comparative analysis of these distributions with the longitudinal profile of the deviations of the zonal thermospheric wind ( 400 km, CHAMP) modulated by the DE3 tidal wave is carried out; their considerable correlation ( R ≅ 0.69) is revealed. We conclude that the longitudinal variations of the zonal wind associated with DE3 tidal waves can effect the longitudinal variations in the appearance frequency of the initial "seeding" perturbations, which further evolve into the plasma bubbles.

High temperature integrated ultrasonic shear and longitudinal wave probes

NASA Astrophysics Data System (ADS)

Ono, Y.; Jen, C.-K.; Kobayashi, M.

2007-02-01

Integrated ultrasonic shear wave probes have been designed and developed using a mode conversion theory for nondestructive testing and characterization at elevated temperatures. The probes consisted of metallic substrates and high temperature piezoelectric thick (>40μm) films through a paint-on method. Shear waves are generated due to mode conversion from longitudinal to shear waves because of reflection inside the substrate having a specific shape. A novel design scheme is proposed to reduce the machining time of substrates and thick film fabrication difficulty. A probe simultaneously generating and receiving both longitudinal and shear waves is also developed and demonstrated. In addition, a shear wave probe using a clad buffer rod consisting of an aluminum core and stainless steel cladding has been developed. All the probes were tested and successfully operated at 150°C.

Longitudinal Surveys of Australian Youth (LSAY) 1998 Cohort: Wave 12 (2009)--Questionnaire. Technical Report 58A

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2010

2010-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the questionnaire for the LSAY 1998 cohort Wave 12 (2009) data set. [For the accompanying frequency tables, "Longitudinal Surveys…

Longitudinal waves in carbon nanotubes in the presence of transverse magnetic field and elastic medium

NASA Astrophysics Data System (ADS)

Liu, Hu; Liu, Hua; Yang, Jialing

2017-09-01

In the present paper, the coupling effect of transverse magnetic field and elastic medium on the longitudinal wave propagation along a carbon nanotube (CNT) is studied. Based on the nonlocal elasticity theory and Hamilton's principle, a unified nonlocal rod theory which takes into account the effects of small size scale, lateral inertia and radial deformation is proposed. The existing rod theories including the classic rod theory, the Rayleigh-Love theory and Rayleigh-Bishop theory for macro solids can be treated as the special cases of the present model. A two-parameter foundation model (Pasternak-type model) is used to represent the elastic medium. The influence of transverse magnetic field, Pasternak-type elastic medium and small size scale on the longitudinal wave propagation behavior of the CNT is investigated in detail. It is shown that the influences of lateral inertia and radial deformation cannot be neglected in analyzing the longitudinal wave propagation characteristics of the CNT. The results also show that the elastic medium and the transverse magnetic field will also affect the longitudinal wave dispersion behavior of the CNT significantly. The results obtained in this paper are helpful for understanding the mechanical behaviors of nanostructures embedded in an elastic medium.

Longitudinal Surveys of Australian Youth (LSAY) 1998 Cohort: Wave 12 (2009)--Frequency Tables. Technical Report 58B

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2010

2010-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the frequency tables for the LSAY 1998 cohort Wave 12 (2009) data set. [For the accompanying questionnaire, "Longitudinal Surveys…

Recruitment Modeling Applied to Longitudinal Studies of Group Differences in Intelligence

ERIC Educational Resources Information Center

Madhyastha, Tara M.; Hunt, Earl; Deary, Ian J.; Gale, Catharine R.; Dykiert, Dominika

2009-01-01

In longitudinal studies data is collected in a series of waves. Each wave after the first suffers from attrition. Therefore it can be difficult to discriminate between changes in sample parameters due to a longitudinal process (e.g. ageing) and changes due to attrition. The problem is particularly vexing if one of the purposes is to compare…

Longitudinal Surveys of Australian Youth (LSAY): 2006 Cohort Wave 4 (2009)--Frequency Tables. Technical Report 56B

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2010

2010-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the frequency tables for the LSAY 2006 cohort Wave 4 (2009) data set. [For the "Longitudinal Surveys of Australian Youth (LSAY):…

Longitudinal Surveys of Australian Youth (LSAY): 2006 Cohort Wave 4 (2009)--Questionnaire. Technical Report 56A

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2010

2010-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the questionnaire for the LSAY 2006 cohort Wave 4 (2009) data set. [For the "Longitudinal Surveys of Australian Youth (LSAY):…

Coupling of an acoustic wave to shear motion due to viscous heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Bin; Goree, J.

2016-07-15

Viscous heating due to shear motion in a plasma can result in the excitation of a longitudinal acoustic wave, if the shear motion is modulated in time. The coupling mechanism is a thermal effect: time-dependent shear motion causes viscous heating, which leads to a rarefaction that can couple into a longitudinal wave, such as an acoustic wave. This coupling mechanism is demonstrated in an electrostatic three-dimensional (3D) simulation of a dusty plasma, in which a localized shear flow is initiated as a pulse, resulting in a delayed outward propagation of a longitudinal acoustic wave. This coupling effect can be profoundmore » in plasmas that exhibit localized viscous heating, such as the dusty plasma we simulated using parameters typical of the PK-4 experiment. We expect that a similar phenomenon can occur with other kinds of plasma waves.« less

Coupling of transverse and longitudinal waves in piano strings.

PubMed

Etchenique, Nikki; Collin, Samantha R; Moore, Thomas R

2015-04-01

The existence of longitudinal waves in vibrating piano strings has been previously established, as has their importance in producing the characteristic sound of the piano. Modeling of the coupling between the transverse and longitudinal motion of strings indicates that the amplitude of the longitudinal waves are quadratically related to the transverse displacement of the string, however, experimental verification of this relationship is lacking. In the work reported here this relationship is tested by driving the transverse motion of a piano string at only two frequencies, which simplifies the task of unambiguously identifying the constituent signals. The results indicate that the generally accepted relationship between the transverse motion and the longitudinal motion is valid. It is further shown that this dependence on transverse displacement is a good approximation when a string is excited by the impact of the hammer during normal play.

Method for measuring liquid viscosity and ultrasonic viscometer

DOEpatents

Sheen, Shuh-Haw; Lawrence, William P.; Chien, Hual-Te; Raptis, Apostolos C.

1994-01-01

An ultrasonic viscometer and method for measuring fluid viscosity are provided. Ultrasonic shear and longitudinal waves are generated and coupled to the fluid. Reflections from the generated ultrasonic shear and longitudinal waves are detected. Phase velocity of the fluid is determined responsive to the detected ultrasonic longitudinal waves reflections. Viscosity of the fluid is determined responsive to the detected ultrasonic shear waves reflections. Unique features of the ultrasonic viscometer include the use of a two-interface fluid and air transducer wedge to measure relative signal change and to enable self calibration and the use of a ratio of reflection coefficients for two different frequencies to compensate for environmental changes, such as temperature.

Study on longitudinal dispersion relation in one-dimensional relativistic plasma: Linear theory and Vlasov simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, H.; Wu, S. Z.; Zhou, C. T.

2013-09-15

The dispersion relation of one-dimensional longitudinal plasma waves in relativistic homogeneous plasmas is investigated with both linear theory and Vlasov simulation in this paper. From the Vlasov-Poisson equations, the linear dispersion relation is derived for the proper one-dimensional Jüttner distribution. Numerically obtained linear dispersion relation as well as an approximate formula for plasma wave frequency in the long wavelength limit is given. The dispersion of longitudinal wave is also simulated with a relativistic Vlasov code. The real and imaginary parts of dispersion relation are well studied by varying wave number and plasma temperature. Simulation results are in agreement with establishedmore » linear theory.« less

Monitoring uniform and localized corrosion in reinforced mortar using high-frequency guided longitudinal wages

NASA Astrophysics Data System (ADS)

Ervin, Benjamin L.; Reis, Henrique; Bernhard, Jennifer T.; Kuchma, Daniel A.

2008-03-01

High-frequency guided longitudinal waves have been used in a through-transmission arrangement to monitor reinforced mortar specimens undergoing both accelerated uniform and localized corrosion. High-frequency guided longitudinal waves were chosen because they have the fastest propagation velocity and lowest theoretical attenuation for the rebar/mortar system. This makes the modes easily discernible and gives them the ability to travel over long distances. The energy of the high-frequency longitudinal waves is located primarily in the center of the rebar, leading to less leakage into the surrounding mortar. The results indicate that the guided mechanical waves are sensitive to both forms of corrosion attack in the form of attenuation, with less sensitivity at higher frequencies. Also promising is the ability to discern uniform corrosion from localized corrosion in a through-transmission arrangement by examination of the frequency domain.

A research about characteristics of longitudinal variations of ES layers irregularities based on CHAMP occultation measurements

NASA Astrophysics Data System (ADS)

Liao, Sunmin

2018-04-01

Based on the data of CHAMP occultation measurements, this paper makes a preliminary analysis of the longitudinal variations of ES irregular structure by using Fourier decomposition and reconstruction technique. It is found that the longitudinal variations of the ES irregular structure show the features of multiple wave-numbers, which is dominated by the wave number 1 to the wave number 5 components, and decrease from the amplitudes of the wave number 6 components. The features of wave number structures are very different in different DIP latitude and different seasons. The number of crests in summer and autumn is mostly 3 or 4 crest structures, while the number of crests in spring achieves 5 at DIP 15°N with small fluctuates, the crests number of winter is the least. In the multiple wave-numbers structure, the wave number 4 component shows a significant dependence on the season, mainly in the summer and autumn, particularly obvious from July to October.

A Fresh Look at Longitudinal Standing Waves on a Spring

NASA Astrophysics Data System (ADS)

Rutherford, Casey

2013-01-01

Transverse standing waves produced on a string, as shown in Fig. 1, are a common demonstration of standing wave patterns that have nodes at both ends. Longitudinal standing waves can be produced on a helical spring that is mounted vertically and attached to a speaker, as shown in Fig. 2, and used to produce both node-node (NN) and node-antinode (NA) standing waves. The resonant frequencies of the two standing wave patterns are related with theory that is accessible to students in algebra-based introductory physics courses, and actual measurements show good agreement with theoretical predictions.

Bolt axial stress measurement based on a mode-converted ultrasound method using an electromagnetic acoustic transducer.

PubMed

Ding, Xu; Wu, Xinjun; Wang, Yugang

2014-03-01

A method is proposed to measure the stress on a tightened bolt using an electromagnetic acoustic transducer (EMAT). A shear wave is generated by the EMAT, and a longitudinal wave is obtained from the reflection of the shear wave due to the mode conversion. The ray paths of the longitudinal and the shear wave are analyzed, and the relationship between the bolt axial stress and the ratio of time of flight between two mode waves is then formulated. Based on the above outcomes, an EMAT is developed to measure the bolt axial stress without loosening the bolt, which is required in the conventional EMAT test method. The experimental results from the measurement of the bolt tension show that the shear and the mode-converted longitudinal waves can be received successfully, and the ratio of the times of flight of the shear and the mode-converted longitudinal waves is linearly proportional to the bolt axial tension. The non-contact characteristic of EMAT eliminates the effect of the couplant and also makes the measurement more convenient than the measurement performed using the piezoelectric transducer. This method provides a promising way to measure the stress on tightened bolts. Copyright © 2013 Elsevier B.V. All rights reserved.

Instability of Longitudinal Wave in Magnetized Strongly Coupled Dusty Plasma

NASA Astrophysics Data System (ADS)

Xie, Bai-Song

2003-12-01

Instability of longitudinal wave in magnetized strongly coupled dusty plasmas is investigated. The dust charging relaxation is taken into account. It is found that there exists threshold of interdust distance for the instability of wave, which is determined significantly by the dust charging relaxation, the coupling parameter of high correlation of dust as well the strength of magnetic field.

Longitudinal associations of intimate partner violence attitudes and perpetration: Dyadic couples data from a randomized controlled trial in rural India

PubMed Central

Shakya, Holly B.; Fleming, Paul; Saggurti, Niranjan; Donta, Balaiah; Silverman, Jay; Raj, Anita

2018-01-01

We conducted longitudinal analyses examining the associations between intimate partner violence (IPV) attitudes and women’s reported IPV in couples (N = 762) using 3 waves of data from a randomized controlled trial in Maharashtra, India. We found that, between Waves 1 and 2, men’s and women’s acceptance of IPV in the overall population decreased significantly while reports of IPV increased. These changes, we hypothesize, are evidence of an exogenous shock, possibly a high profile rape in Delhi in December 2012, that may have impacted the entire population. Cross-sectional associations between men’s attitudes towards IPV and reported IPV were not significant in Wave 1, while positively and significantly associated in Waves 2 and 3. Longitudinal analysis showed that reduction in men’s acceptance of IPV between Waves 1 and 2 was associated with a lower likelihood of reported IPV in Wave 3. Women’s Wave 1 acceptance of IPV was positively associated with reported IPV in the Wave 1 cross-sectional analysis, while Wave 2 and Wave 3 measures of IPV acceptance were negatively associated with reported IPV in Waves 2 and 3 respectively. Longitudinal analyses of the change in women’s attitudes towards IPV from Wave 1 to 2 and reported IPV in Wave 3 were insignificant. However, When women first reported IPV in Waves 2 or 3 they were less likely to report acceptance of IPV in that same wave. Findings suggest that changes in husbands’ IPV acceptance is predictive of subsequent IPV, while newly experienced IPV predicts decreased IPV acceptance for women. Wave 2 and Wave 3 results were significant for the control group only, evidence that the intervention affected those associations, potentially changing attitudes more quickly than behavior. We recommend interventions that expose community opposition to IPV as a new social norm, and analysis of how the 2012 Delhi rape case may have affected these norms. PMID:28260640

E-cigarette advertising exposure in e-cigarette naïve adolescents and subsequent e-cigarette use: A longitudinal cohort study.

PubMed

Camenga, Deepa; Gutierrez, Kevin M; Kong, Grace; Cavallo, Dana; Simon, Patricia; Krishnan-Sarin, Suchitra

2018-06-01

Electronic (E-) cigarettes are one of the most popular tobacco products used by adolescents today. This study examined whether exposure to advertisements in (1) social networking sites (Facebook, Twitter, YouTube, Pinterest/Google Plus), (2) traditional media (television/radio, magazines, billboards), or (3) retail stores (convenience stores, mall kiosks, tobacco shops) was associated with subsequent e-cigarette use in a longitudinal cohort of adolescents. Data were drawn from longitudinal surveys conducted in fall 2013 (wave 1) and spring 2014 (wave 2) of a school-based cohort attending 3 high schools and 2 middle schools in Connecticut. Adolescents were asked about tobacco use behaviors and where they had recently seen e-cigarette advertising at wave 1. We used logistic regression to determine whether advertising exposure at wave 1 increased the odds of e-cigarette use by wave 2, controlling for demographics and cigarette smoking status at wave 1. Among those who have never used e-cigarettes in wave 1 (n = 1742), 9.6% reported e-cigarette use at wave 2. Multivariate logistic regression demonstrated that exposure to e-cigarette advertising on Facebook (OR 2.12 = p < 0.02) at wave 1, but not other venues, significantly increased the odds of subsequent e-cigarette use wave 2. Age, white race, and cigarette smoking at wave 1 also was associated with e-cigarette use at wave 2. This study provides one of the first longitudinal examinations demonstrating that exposure to e-cigarette advertising on social networking sites among youth who had never used e-cigarettes increases the likelihood of subsequent e-cigarette use. Copyright © 2018 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hatano, H.; Watanabe, T.

A new system was developed for the reciprocity calibration of acoustic emission transducers in Rayleigh-wave and longitudinal-wave sound fields. In order to reduce interference from spurious waves due to reflections and mode conversions, a large cylindrical block of forged steel was prepared for the transfer medium, and direct and spurious waves were discriminated between on the basis of their arrival times. Frequency characteristics of velocity sensitivity to both the Rayleigh wave and longitudinal wave were determined in the range of 50 kHz{endash}1 MHz by means of electrical measurements without the use of mechanical sound sources or reference transducers. {copyright} {italmore » 1997 Acoustical Society of America.}« less

Wave propagation in fluid-conveying viscoelastic carbon nanotubes under longitudinal magnetic field with thermal and surface effect via nonlocal strain gradient theory

NASA Astrophysics Data System (ADS)

Zhen, Yaxin; Zhou, Lin

2017-03-01

Based on nonlocal strain gradient theory, wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes (SWCNTs) is studied in this paper. With consideration of thermal effect and surface effect, wave equation is derived for fluid-conveying viscoelastic SWCNTs under longitudinal magnetic field utilizing Euler-Bernoulli beam theory. The closed-form expressions are derived for the frequency and phase velocity of the wave motion. The influences of fluid flow velocity, structural damping coefficient, temperature change, magnetic flux and surface effect are discussed in detail. SWCNTs’ viscoelasticity reduces the wave frequency of the system and the influence gets remarkable with the increase of wave number. The fluid in SWCNTs decreases the frequency of wave propagation to a certain extent. The frequency (phase velocity) gets larger due to the existence of surface effect, especially when the diameters of SWCNTs and the wave number decrease. The wave frequency increases with the increase of the longitudinal magnetic field, while decreases with the increase of the temperature change. The results may be helpful for better understanding the potential applications of SWCNTs in nanotechnology.

Effects of exposure to rocket attacks on adolescent distress and violence: a 4-year longitudinal study.

PubMed

Henrich, Christopher C; Shahar, Golan

2013-06-01

The effects of Israeli adolescents' exposure to rocket attacks over time were examined, focusing on anxiety, depression, aggression, and violence commission. A sample of 362 adolescents from southern Israel was followed from 2008 through 2011 with four annual assessments. Measures included exposure to rocket attacks (gauging whether children were affected by rocket attacks, both directly and indirectly, through friends and family), anxiety (items from the State Anxiety Inventory), depression (the Center for Epidemiological Studies Child Depression Scale), aggression (the Orpinas Aggression Scale), and violence commission (from the Social and Health Assessment). Concurrent and longitudinal findings differed. Wave 1 exposure to rockets attacks was associated with Wave 1 anxiety, depression, and aggression. Longitudinal results evinced only modest effects of exposure on anxiety and depression, no effects on aggression, but robust effects on violence commission. Exposure to terror attacks before the study predicted increased odds of violence commission at the fourth and final wave, controlling for violence commission at the first, second, and third wave. Exposure to rocket attacks in the second wave predicted increased odds of violence commission at the third wave. This is the first longitudinal study attesting to the prospective longitudinal effect of exposure to terrorism on adolescent violence. Findings should serve as a red flag for health care practitioners working in civil areas afflicted by terrorism and political violence. Copyright © 2013 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

Students dance longitudinal standing waves

NASA Astrophysics Data System (ADS)

Ruiz, Michael J.

2017-05-01

A demonstration is presented that involves students dancing longitudinal standing waves. The resulting kinaesthetic experience and visualization both contribute towards an understanding of the natural modes of vibrations in open and closed pipes. A video of this fun classroom activity is provided (http://mjtruiz.com/ped/dance/).

Tissue elasticity of in vivo skeletal muscles measured in the transverse and longitudinal planes using shear wave elastography.

PubMed

Chino, Kentaro; Kawakami, Yasuo; Takahashi, Hideyuki

2017-07-01

The aim of the present study was to measure in vivo skeletal muscle elasticity in the transverse and longitudinal planes using shear wave elastography and then to compare the image stability, measurement values and measurement repeatability between these imaging planes. Thirty-one healthy males participated in this study. Tissue elasticity (shear wave velocity) of the medial gastrocnemius, rectus femoris, biceps brachii and rectus abdominis was measured in both the transverse and longitudinal planes using shear wave elastography. Image stability was evaluated by the standard deviation of the colour distribution in the shear wave elastography image. Measurement repeatability was assessed by the coefficient of variance obtained from three measurement values. Image stability of all tested muscles was significantly higher in the longitudinal plane (P<0·001), but measurement repeatability did not differ significantly between the imaging planes (P>0·05), except in the biceps brachii (P = 0·001). Measurement values of the medial gastrocnemius, rectus femoris and biceps brachii were significantly different between the imaging planes (P<0·001). Image stability and measurement values of shear wave elastography images varied with imaging plane, which indicates that imaging plane should be considered when measuring skeletal muscle tissue elasticity by shear wave elastography. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

A Method of Poisson's Ration Imaging Within a Material Part

NASA Technical Reports Server (NTRS)

Roth, Don J. (Inventor)

1994-01-01

The present invention is directed to a method of displaying the Poisson's ratio image of a material part. In the present invention, longitudinal data is produced using a longitudinal wave transducer and shear wave data is produced using a shear wave transducer. The respective data is then used to calculate the Poisson's ratio for the entire material part. The Poisson's ratio approximations are then used to display the data.

Method of Poisson's ratio imaging within a material part

NASA Technical Reports Server (NTRS)

Roth, Don J. (Inventor)

1996-01-01

The present invention is directed to a method of displaying the Poisson's ratio image of a material part. In the present invention longitudinal data is produced using a longitudinal wave transducer and shear wave data is produced using a shear wave transducer. The respective data is then used to calculate the Poisson's ratio for the entire material part. The Poisson's ratio approximations are then used to displayed the image.

Optical generation and detection of gigahertz-frequency longitudinal and shear acoustic waves in liquids: Theory and experiment

NASA Astrophysics Data System (ADS)

Klieber, Christoph; Pezeril, Thomas; Andrieu, Stéphane; Nelson, Keith A.

2012-07-01

We describe an adaptation of picosecond laser ultrasonics tailored for study of GHz-frequency longitudinal and shear acoustic waves in liquids. Time-domain coherent Brillouin scattering is used to detect multicycle acoustic waves after their propagation through variable thickness liquid layers into a solid substrate. A specialized optical pulse shaping method is used to generate sequences of pulses whose repetition rate determines the acoustic frequency. The measurements reveal the viscoelastic liquid properties and also include signatures of the optical and acoustic cavities formed by the multilayer sample assembly. Modeling of the signals allows their features to be distinguished so that liquid properties can be extracted reliably. Longitudinal and shear acoustic wave data from glycerol and from the silicon oil DC704 are presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ping; Deng, Yuqun; Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024

In relativistic backward wave oscillators (RBWOs), although the slow wave structure (SWS) and electron beam determine the main characteristics of beam-wave interaction, many other factors can also significantly affect the microwave generation process. This paper investigates the influence of voltage rise time on beam-wave interaction in RBWOs. Preliminary analysis and PIC simulations demonstrate if the voltage rise time is moderately long, the microwave frequency will gradually increase during the startup process until the voltage reaches its amplitude, which can be explained by the dispersion relation. However, if the voltage rise time is long enough, the longitudinal resonance of the finitely-longmore » SWS will force the RBWO to work with unwanted longitudinal modes for a while and then gradually hop to the wanted longitudinal mode, and this will lead to an impure microwave frequency spectrum. Besides, a longer voltage rise time will delay the startup process and thus lead to a longer microwave saturation time. And if unwanted longitudinal modes are excited due to long voltage rise time, the microwave saturation time will be further lengthened. Therefore, the voltage rise time of accelerators adopted in high power microwave technology should not be too long in case unwanted longitudinal modes are excited.« less

Longitudinal direct and indirect pathways linking older sibling competence to the development of younger sibling competence.

PubMed

Brody, Gene H; Kim, Sooyeon; Murry, Velma McBride; Brown, Anita C

2003-05-01

A 4-wave longitudinal model tested direct and indirect links between older sibling (OS; M = 11.7 years) and younger sibling (YS; M = 9.2 years) competence in 152 rural African American families. Data were collected at 1-year intervals. At each wave, different teachers assessed OS competence, YS competence, and YS self-regulation. Mothers reported their own psychological functioning; mothers and YSs reported parenting practices toward the YS. OS competence was stable across time and was linked with positive changes in mothers' psychological functioning from Wave 1 to Wave 2. Mothers' Wave 2 psychological functioning was associated with involved-supportive parenting of the YS at Wave 3. OS Wave 2 competence and Wave 3 parenting were indirectly linked with Wave 4 YS competence, through Wave 3 YS self-regulation. Structural equation modeling controlled for Wave 1 YS competence; thus, the model accounted for change in YS competence across 3 years.

A rod type linear ultrasonic motor utilizing longitudinal traveling waves: proof of concept

NASA Astrophysics Data System (ADS)

Wang, Liang; Wielert, Tim; Twiefel, Jens; Jin, Jiamei; Wallaschek, Jörg

2017-08-01

This paper proposes a non-resonant linear ultrasonic motor utilizing longitudinal traveling waves. The longitudinal traveling waves in the rod type stator are generated by inducing longitudinal vibrations at one end of the waveguide and eliminating reflections at the opposite end by a passive damper. Considering the Poisson’s effect, the stator surface points move on elliptic trajectories and the slider is driven forward by friction. In contrast to many other flexural traveling wave linear ultrasonic motors, the driving direction of the proposed motor is identical to the wave propagation direction. The feasibility of the motor concept is demonstrated theoretically and experimentally. First, the design and operation principle of the motor are presented in detail. Then, the stator is modeled utilizing the transfer matrix method and verified by experimental studies. In addition, experimental parameter studies are carried out to identify the motor characteristics. Finally, the performance of the proposed motor is investigated. Overall, the results indicate very dynamic drive characteristics. The motor prototype achieves a maximum mean velocity of 115 mm s-1 and a maximum load of 0.25 N. Thereby, the start-up and shutdown times from the maximum speed are lower than 5 ms.

Elastic metamaterials with simultaneously negative effective shear modulus and mass density.

PubMed

Wu, Ying; Lai, Yun; Zhang, Zhao-Qing

2011-09-02

We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess a negative shear modulus and negative mass density over a large frequency region. Such a material has the unique property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refraction, which is demonstrated by using a wedge sample and a significant amount of mode conversion from transverse waves to longitudinal waves that cannot occur on the interface of two natural solids.

Self-injection of electrons in a laser-wakefield accelerator by using longitudinal density ripple

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahiya, Deepak; Sharma, A. K.; Sajal, Vivek

By introducing a longitudinal density ripple (periodic modulation in background plasma density), we demonstrate self-injection of electrons in a laser-wakefield accelerator. The wakefield driven plasma wave, in presence of density ripple excites two side band waves of same frequency but different wave numbers. One of these side bands, having smaller phase velocity compared to wakefield driven plasma wave, preaccelerates the background plasma electrons. Significant number of these preaccelerated electrons get trapped in the laser-wakefield and further accelerated to higher energies.

Apparatus for checking the direction of polarization of shear-wave ultrasonic transducers

DOEpatents

Karplus, Henry H. B.

1980-01-01

An apparatus for checking the direction of polarization of shear-wave ultrasonic transducers comprises a first planar surface for mounting the shear-wave transducer, a second planar surface inclined at a predetermined angle to the first surface to generate longitudinal waves by mode conversion, and a third planar surface disposed at a second predetermined angle to the first for mounting a longitudinal-wave ultrasonic transducer. In an alternate embodiment, two second planar surfaces at the predetermined angle are placed at an angle to each other. The magnitude of the shear wave is a function of the angle between the direction of polarization of the transducer and the mode-conversion surface.

Apparatus for checking the direction of polarization of shear-wave ultrasonic transducers

DOEpatents

Karplus, H.H.B.; Forster, G.A.

An apparatus for checking the direction of polarization of shear-wave ultrasonic transducers comprises a first planar surface for mounting the shear-wave transducer, a second planar surface inclined at a predetermined angle to the first surface to generate longitudinal waves by mode conversion, and a third planar surface disposed at a second predetermined angle to the first for mounting a longitudinal-wave ultransonic transducer. In an alternate embodiment, two second planar surfaces at the predetermined angle are placed at an angle to each other. The magnitude of the shear wave is a function of the angle between the direction of polarization of the transducer and the mode-conversion surface.

Retaining young people in a longitudinal sexual health survey: a trial of strategies to maintain participation

PubMed Central

2010-01-01

Background There is an increasing trend towards lower participation in questionnaire surveys. This reduces representativeness, increases costs and introduces particular challenges to longitudinal surveys, as researchers have to use complex statistical techniques which attempt to address attrition. This paper describes a trial of incentives to retain longitudinal survey cohorts from ages 16 to 20, to question them on the sensitive topic of sexual health. Methods A longitudinal survey was conducted with 8,430 eligible pupils from two sequential year groups from 25 Scottish schools. Wave 1 (14 years) and Wave 2 (16 years) were conducted largely within schools. For Wave 3 (18 years), when everyone had left school, the sample was split into 4 groups that were balanced across predictors of survey participation: 1) no incentive; 2) chance of winning one of twenty-five vouchers worth £20; 3) chance of winning one £500 voucher; 4) a definite reward of a £10 voucher sent on receipt of their completed questionnaire. Outcomes were participation at Wave 3 and two years later at Wave 4. Analysis used logistic regression and adjusted for clustering at school level. Results The only condition that had a significant and beneficial impact for pupils was to offer a definite reward for participation (Group 4). Forty-one percent of Group 4 participated in Wave 3 versus 27% or less for Groups 1 to 3. At Wave 4, 35% of Group 4 took part versus 25% or less for the other groups. Similarly, 22% of Group 4 participated in all four Waves of the longitudinal study, whereas for the other three groups it was 16% or less that participated in full. Conclusions The best strategy for retaining all groups of pupils and one that improved retention at both age 18 and age 20 was to offer a definite reward for participation. This is expensive, however, given the many benefits of retaining a longitudinal sample, we recommend inclusion of this as a research cost for cohort and other repeat-contact studies. PMID:20109221

Distribution of Longitudinal Wave Velocities in Bovine Cortical Bone in vitro

NASA Astrophysics Data System (ADS)

Yamato, Yu; Kataoka, Hideo; Matsukawa, Mami; Yamazaki, Kaoru; Otani, Takahiko; Nagano, Akira

2005-06-01

The distribution of longitudinal wave velocities and longitudinal moduli in a bovine femoral cortical bone was experimentally investigated. In all parts of the long cylindrical bone, the velocities and longitudinal moduli in the axial direction were the highest. In the anterior (A) part, the velocities in the axial direction were high and almost constant, whereas the velocities in the proximal postero medial (PM) and distal postero lateral (PL) parts markedly decreased. Classifying the cortical bone into three structures (plexiform, Haversian, and porotic), we clarify the velocity distributions in the bone with discussion from an anatomical point of view.

Sound

NASA Astrophysics Data System (ADS)

Capstick, J. W.

2013-01-01

1. The nature of sound; 2. Elasticity and vibrations; 3. Transverse waves; 4. Longitudinal waves; 5. Velocity of longitudinal waves; 6. Reflection and refraction. Doppler's principle; 7. Interference. Beats. Combination tones; 8. Resonance and forced vibrations; 9. Quality of musical notes; 10. Organ pipes; 11. Rods. Plates. Bells; 12. Acoustical measurements; 13. The phonograph, microphone and telephone; 14. Consonance; 15. Definition of intervals. Scales. Temperament; 16. Musical instruments; 17. Application of acoustical principles to military purposes; Questions; Answers to questions; Index.

The effect of transverse wave vector and magnetic fields on resonant tunneling times in double-barrier structures

NASA Astrophysics Data System (ADS)

Wang, Hongmei; Zhang, Yafei; Xu, Huaizhe

2007-01-01

The effect of transverse wave vector and magnetic fields on resonant tunneling times in double-barrier structures, which is significant but has been frequently omitted in previous theoretical methods, has been reported in this paper. The analytical expressions of the longitudinal energies of quasibound levels (LEQBL) and the lifetimes of quasibound levels (LQBL) in symmetrical double-barrier (SDB) structures have been derived as a function of transverse wave vector and longitudinal magnetic fields perpendicular to interfaces. Based on our derived analytical expressions, the LEQBL and LQBL dependence upon transverse wave vector and longitudinal magnetic fields has been explored numerically for a SDB structure. Model calculations show that the LEQBL decrease monotonically and the LQBL shorten with increasing transverse wave vector, and each original LEQBL splits to a series of sub-LEQBL which shift nearly linearly toward the well bottom and the lifetimes of quasibound level series (LQBLS) shorten with increasing Landau-level indices and magnetic fields.

Negative emotions and behaviour: The role of regulatory emotional self-efficacy.

PubMed

Mesurado, Belén; Vidal, Elisabeth Malonda; Mestre, Anna Llorca

2018-04-01

The objective of this study is to test a longitudinal model that analyses the direct effect of negative emotions (anger, depression and anxiety, wave 1) on prosocial and aggressive behaviour (wave 2) in adolescents. And the indirect effect of negative emotions (wave 1) on prosocial and aggressive behaviour (wave 2) through regulatory emotional self-efficacy. Data was obtained from 417 adolescents in a two-wave longitudinal study (225 girls, M age = 14.70 years) from schools located in Valencia, Spain. SEM was employed to explore longitudinal models. The results showed that anger had a direct relationship with prosocial behaviour and aggression, measured two years later. However, the depression and anxiety states did not predict prosociality and aggressiveness. The mediation role of regulatory emotional self-efficacy between negative emotion and behaviours was only partially confirmed. Finally, only the perception of self-efficacy in expressing positive affect is related to prosociality and aggressiveness. Copyright © 2018 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Longitudinal Surveys of Australian Youth (LSAY) 2009 Cohort: Wave 2 (2010)-- Questionnaire. Technical Report 71A

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the questionnaire for the LSAY 2009 cohort Wave 2 (2010) data set.

Longitudinal Surveys of Australian Youth (LSAY) 2009 Cohort: Wave 3 (2011)--Questionnaire. Technical Report 72A

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the questionnaire for the LSAY 2009 cohort Wave 3 (2011) data set.

Longitudinal Surveys of Australian Youth (LSAY) 2009 Cohort: Wave 2 (2010)--Frequency Tables. Technical Report 71B

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the frequency tables for the LSAY 2009 cohort Wave 2 (2010) data set.

Single-longitudinal mode Nd:YVO4 microchip laser with orthogonal-polarization bidirectional traveling-waves mode.

PubMed

Ma, Yingjun; Wu, Li; Wu, Hehui; Chen, Weimin; Wang, Yanli; Gu, Shijie

2008-11-10

We present a single longitudinal mode, diode pumped Nd:YVO(4) microchip laser where a pair of quarter-wave plates (QWPs) sandwich Nd:YVO(4) and the principle axes of QWPs are oriented at 45 degrees to the c-axis of Nd:YVO(4). Three pieces of crystals were optically bonded together as a microchip without adhesive. Owing to large birefringence of Nd:YVO(4), two standing waves with orthogonal polarizations compensate their hole-burning effects with each other, which diminish total spatial hole-burning effects in Nd:YVO(4). The maximum pump power of greater than 25 times the threshold for single longitudinal mode operation has been theoretically shown and experimentally demonstrated. The power of output, slope efficiencies and temperature range of single longitudinal mode operation are greater than 730 mw (at 1.25 W pump), 60% and 30 degrees C, respectively.

High power single-longitudinal-mode Ho:YLF unidirectional ring laser based on a composite structure of acousto-optic device and wave plate

NASA Astrophysics Data System (ADS)

Dai, T. Y.; Fan, Z. G.; Wu, J.; Ju, Y. L.; Yao, B. Q.; Zhang, Z. G.; Teng, K.; Xu, X. G.; Duan, X. M.

2017-05-01

We report a unidirectional single-longitudinal-mode Ho:YLF ring laser. An acousto-optic modulator and two half-wave plates were used to enforce the Ho:YLF ring laser in a unidirectional operation. The single-longitudinal-mode output power could reach 3.73 W successfully when the incident pump power was 16.4 W. The corresponding slope efficiency was 27.1%. The wavelength of the single-longitudinal-mode Ho:YLF ring laser was 2063.8 nm. The M2 factor was 1.12. The results illustrated that the single-longitudinal-mode output power could be further enhanced by increasing the radio frequency power of the acousto-optic modulator.

Orthogonal wave propagation of epileptiform activity in the planar mouse hippocampus in vitro.

PubMed

Kibler, Andrew B; Durand, Dominique M

2011-09-01

In vitro brain preparations have been used extensively to study the generation and propagation of epileptiform activity. Transverse and longitudinal slices of the rodent hippocampus have revealed various patterns of propagation. Yet intact connections between the transverse and longitudinal pathways should generate orthogonal (both transverse and longitudinal) propagation of seizures involving the entire hippocampus. This study utilizes the planar unfolded mouse hippocampus preparation to reveal simultaneous orthogonal epileptiform propagation and to test a method of arresting propagation. This study utilized an unfolded mouse hippocampus preparation. It was chosen due to its preservation of longitudinal neuronal processes, which are thought to play an important role in epileptiform hyperexcitability. 4-Aminopyridine (4-AP), microelectrodes, and voltage-sensitive dye imaging were employed to investigate tissue excitability. In 50-μm 4-AP, stimulation of the stratum radiatum induced transverse activation of CA3 cells but also induced a longitudinal wave of activity propagating along the CA3 region at a speed of 0.09 m/s. Without stimulation, a wave originated at the temporal CA3 and propagated in a temporal-septal direction could be suppressed with glutamatergic receptor antagonists. Orthogonal propagation traveled longitudinally along the CA3 pathway, secondarily invading the CA1 region at a velocity of 0.22 ± 0.024 m/s. Moreover, a local lesion restricted to the CA3 region could arrest wave propagation. These results reveal a complex two-dimensional epileptiform wave propagation pattern in the hippocampus that is generated by a combination of synaptic transmission and axonal propagation in the CA3 recurrent network. Epileptiform propagation block via a transverse selective CA3 lesion suggests a potential surgical technique for the treatment of temporal lobe epilepsy. Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.

Orthogonal Wave Propagation of Epileptiform Activity in the Planar Mouse Hippocampus in vitro

PubMed Central

Kibler, Andrew B; Durand, Dominique M

2011-01-01

Purpose In vitro brain preparations have been used extensively to study the generation and propagation of epileptiform activity. Transverse and longitudinal slices of the rodent hippocampus have revealed various patterns of propagation. Yet intact connections between the transverse and longitudinal pathways should generate orthogonal (both transverse and longitudinal) propagation of seizures involving the entire hippocampus. This study utilizes the planar unfolded mouse hippocampus preparation to reveal simultaneous orthogonal epileptiform propagation and to test a method of arresting propagation. Methods This study utilized an unfolded mouse hippocampus preparation. It was chosen due to its preservation of longitudinal neuronal processes which are thought to play an important role in epileptiform hyper-excitability. 4-aminopyridine (4-AP), micro-electrodes, and voltage sensitive dye imaging were employed to investigate tissue excitability. Key Findings In 50 μM 4-AP, stimulation of the stratum radiatum induced transverse activation of CA3 cells but also induced a longitudinal wave of activity propagating along the CA3 region at a speed of 0.09 m/s. Without stimulation, a wave originated at the temporal CA3 and propagated in a temporal–septal direction and could be suppressed with glutamatergic antagonists. Orthogonal propagation traveled longitudinally along the CA3 pathway, secondarily invading the CA1 region at a velocity of 0.22±0.024 m/s. Moreover, a local lesion restricted to the CA3 region could arrest wave propagation. Significance These results reveal a complex two-dimensional epileptiform wave propagation pattern in the hippocampus that is generated by a combination of synaptic transmission and axonal propagation in the CA3 recurrent network. Epileptiform propagation block via a transverse selective CA3 lesion suggests a potential surgical technique for the treatment of temporal lobe epilepsy. PMID:21668440

Stochastic particle instability for electron motion in combined helical wiggler, radiation, and longitudinal wave fields

NASA Astrophysics Data System (ADS)

Davidson, Ronald C.; McMullin, Wayne A.

1982-07-01

The relativistic motion of an electron is calculated in the combined fields of a transverse helical wiggler field (axial wavelength is λ0=2πk0) and the constant-amplitude, circularly polarized primary electromagnetic wave (δBT,ω,k) propagating in the z direction. For particle velocity near the beat-wave phase velocity ω(k+k0) of the primary wave, it is shown that the presence of a second, moderate-amplitude longitudinal wave (δÊL,ω,k) or transverse electromagnetic wave (δB2,ω2,k2) can lead to stochastic particle instability in which particles trapped near the separatrix of the primary wave undergo a systematic departure from the potential well. The condition for onset of instability is calculated, and the importance of these results for free-electron-laser (FEL) application is discussed. For development of long-pulse or steady-state free-electron lasers, the maintenance of beam integrity for an extended period of time will be of considerable practical importance. The fact that the presence of secondary, moderate-amplitude longitudinal or transverse electromagnetic waves can destroy coherent motion for certain classes of beam particles moving with velocity near ω(k+k0) may lead to a degradation of beam quality and concomitant modification of FEL emission properties.

Longitudinal wave function control in single quantum dots with an applied magnetic field

PubMed Central

Cao, Shuo; Tang, Jing; Gao, Yunan; Sun, Yue; Qiu, Kangsheng; Zhao, Yanhui; He, Min; Shi, Jin-An; Gu, Lin; Williams, David A.; Sheng, Weidong; Jin, Kuijuan; Xu, Xiulai

2015-01-01

Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots. PMID:25624018

Longitudinal wave function control in single quantum dots with an applied magnetic field.

PubMed

Cao, Shuo; Tang, Jing; Gao, Yunan; Sun, Yue; Qiu, Kangsheng; Zhao, Yanhui; He, Min; Shi, Jin-An; Gu, Lin; Williams, David A; Sheng, Weidong; Jin, Kuijuan; Xu, Xiulai

2015-01-27

Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots.

Trajectories of electrons with large longitudinal momenta in the phase plane during surfatron acceleration by an electromagnetic wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mkrtichyan, G. S., E-mail: hay-13@mail.ru

2015-07-15

The trajectories of electrons with large longitudinal momenta in the phase plane in the course of their surfatron acceleration by an electromagnetic wave propagating in space plasma across the external magnetic field are analyzed. Electrons with large longitudinal momenta are trapped immediately if the initial wave phase Ψ(0) on the particle trajectory is positive. For negative values of Ψ(0), no electrons trapping by the wave is observed over the available computational times. According to numerical calculations, the trajectories of trapped particles in the phase plane have a singular point of the stable focus type and the behavior of the trajectorymore » corresponds to the motion in a complex nonstationary effective potential well. For some initial phases, electrons are confined in the region of the accelerating electric field for relatively short time, the energy gain being about 50–130% and more.« less

Band transition and topological interface modes in 1D elastic phononic crystals.

PubMed

Yin, Jianfei; Ruzzene, Massimo; Wen, Jihong; Yu, Dianlong; Cai, Li; Yue, Linfeng

2018-05-01

In this report, we design a one-dimensional elastic phononic crystal (PC) comprised of an Aluminum beam with periodically arranged cross-sections to study the inversion of bulk bands due to the change of topological phases. As the geometric parameters of the unit cell varies, the second bulk band closes and reopens forming a topological transition point. This phenomenon is confirmed for both longitudinal waves and bending waves. By constructing a structural system formed by two PCs with different topological phases, for the first time, we experimentally demonstrate the existence of interface mode within the bulk band gap as a result of topological transition for both longitudinal and bending modes in elastic systems, although for bending modes, additional conditions have to be met in order to have the interface mode due to the dispersive nature of the bending waves in uniform media compared to the longitudinal waves.

Reciprocal Associations between Identity and Civic Engagement in Adolescence: A Two-Wave Longitudinal Study

ERIC Educational Resources Information Center

Crocetti, Elisabetta; Garckija, Renata; Gabrialaviciute, Ingrida; Vosylis, Rimantas; Zukauskiene, Rita

2014-01-01

The purpose of this two-wave longitudinal study was to analyze reciprocal associations between identity styles (i.e., socio-cognitive strategies that individuals adopt in processing, structuring, utilizing, and revising self-relevant information) and civic engagement in adolescence. Participants were 1,308 high school students (9-11 grades; 52.9%…

Teacher-Child Relationships and Social Competence: A Two-Year Longitudinal Study of Chinese Preschoolers

ERIC Educational Resources Information Center

Zhang, Xiao; Nurmi, Jari-Erik

2012-01-01

Based on a two-year and three-wave longitudinal sample of 118 Chinese preschoolers, the present study examined the cross-lagged associations between teacher-child relationships and social competence, and the cross-system generalization of social competence between home and school. At each of the three waves, teachers rated the children's…

Longitudinal waves in a perpendicular collisionless plasma shock. IV - Gradient B.

NASA Technical Reports Server (NTRS)

Gary, S. P.

1972-01-01

The consideration of elastic waves in a Vlasov plasma of unmagnetized ions and magnetized electrons undergoing E x B electron drift and gradient B drift, pursued in the earlier three parts, is brought to conclusion in this last part of the longitudinal wave study in a collisionless plasma shock. Detailed calculations of the effects of the beta sub e dimensionless parameter on the E x B electron drift instability are presented. It is shown that the range of propagation of the elastic waves about the perpendicular remains quite narrow, and that, for oblique propagation, the already narrow angular range of unstable waves is decreased by increases in the value of the beta sub e dimensionless parameter. Also, increases in wave number generally reduce the growth rate and the angular range of propagation.

Protective longitudinal paths linking child competence to behavioral problems among African American siblings.

PubMed

Brody, Gene H; Kim, Sooyeon; Murry, Velma McBride; Brown, Anita C

2004-01-01

A 4-wave longitudinal design was used to examine protective links from child competence to behavioral problems in first- (M=10.97 years) and second- (M=8.27 years) born rural African American children. At 1-year intervals, teachers assessed child behavioral problems, mothers reported their psychological functioning, and both mothers and children reported parenting practices. Structural equation modeling indicated that child competence was linked with residualized positive changes in mothers' psychological functioning from Wave 1 to Wave 2. Mothers' psychological functioning and child competence at Wave 2 forecast involved-supportive parenting at Wave 3, which was associated negatively with externalizing and internalizing problems at Wave 4. The importance of replicating processes leading to outcomes among children in the same study is discussed.

Shear waves in vegetal tissues at ultrasonic frequencies

NASA Astrophysics Data System (ADS)

Fariñas, M. D.; Sancho-Knapik, D.; Peguero-Pina, J. J.; Gil-Pelegrín, E.; Gómez Álvarez-Arenas, T. E.

2013-03-01

Shear waves are investigated in leaves of two plant species using air-coupled ultrasound. Magnitude and phase spectra of the transmission coefficient around the first two orders of the thickness resonances (normal and oblique incidence) have been measured. A bilayer acoustic model for plant leaves (comprising the palisade parenchyma and the spongy mesophyll) is proposed to extract, from measured spectra, properties of these tissues like: velocity and attenuation of longitudinal and shear waves and hence Young modulus, rigidity modulus, and Poisson's ratio. Elastic moduli values are typical of cellular solids and both, shear and longitudinal waves exhibit classical viscoelastic losses. Influence of leaf water content is also analyzed.

Global strength assessment in oblique waves of a large gas carrier ship, based on a non-linear iterative method

NASA Astrophysics Data System (ADS)

Domnisoru, L.; Modiga, A.; Gasparotti, C.

2016-08-01

At the ship's design, the first step of the hull structural assessment is based on the longitudinal strength analysis, with head wave equivalent loads by the ships' classification societies’ rules. This paper presents an enhancement of the longitudinal strength analysis, considering the general case of the oblique quasi-static equivalent waves, based on the own non-linear iterative procedure and in-house program. The numerical approach is developed for the mono-hull ships, without restrictions on 3D-hull offset lines non-linearities, and involves three interlinked iterative cycles on floating, pitch and roll trim equilibrium conditions. Besides the ship-wave equilibrium parameters, the ship's girder wave induced loads are obtained. As numerical study case we have considered a large LPG liquefied petroleum gas carrier. The numerical results of the large LPG are compared with the statistical design values from several ships' classification societies’ rules. This study makes possible to obtain the oblique wave conditions that are inducing the maximum loads into the large LPG ship's girder. The numerical results of this study are pointing out that the non-linear iterative approach is necessary for the computation of the extreme loads induced by the oblique waves, ensuring better accuracy of the large LPG ship's longitudinal strength assessment.

Longitudinal Surveys of Australian Youth (LSAY): 2003 Cohort Wave 7 (2009)--Frequency Tables. Technical Report 57B

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2010

2010-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the frequency tables for the LSAY 2003 cohort Wave 7 (2009) data set. [For the related questionnaire, see ED512164.

Longitudinal Surveys of Australian Youth (LSAY) 2009 Cohort: Wave 3 (2011)--Frequency Tables. Technical Report 72B

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the frequency tables for the LSAY 2009 cohort Wave 3 (2011) data set. [For the related questionnaire, see ED536306.

Longitudinal Surveys of Australian Youth (LSAY) 2003 Cohort: Wave 7 (2009)--Questionnaire. Technical Report 57A

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2010

2010-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This technical paper contains the questionnaire for the LSAY 2003 cohort Wave 7 (2009) data set. [For the related frequency tables, see ED512163.

Longitudinal Surveys of Australian Youth (LSAY) 2006 Cohort: Wave 6 (2011)--Questionnaire. Technical Report 75A

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This series of documents provides supporting information for the LSAY data set of the 2006 cohort at wave 6 (2011). The document presents the questionnaire for LSAY…

Electromagnetic plasma wave propagation along a magnetic field. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Olson, C. L.

1970-01-01

The linearized response of a Vlasov plasma to the steady-state excitation of transverse plasma waves along an external magnetic field is examined. Assuming a delta-function excitation mechanism, and performing a detailed Vlasov-Maxwell equation analysis using Fourier-Laplace transforms, the plasma response is found to consist of three terms: a branch-cut term, a free-streaming term, and a dielectric-pole term. Also considered is the phenomenon of plasma wave echoes. The case of longitudinal electrostatic waves is extended to the case of transverse plasma waves that propagate along an external magnetic field. It is shown that a transverse echo results in lowest order only when one excitation is transverse and the other is longitudinal.

Modified screening interaction potential on dust lattice waves in dusty plasma ring

NASA Astrophysics Data System (ADS)

He, Kerong; Chen, Hui; Liu, Sanqiu

2017-05-01

In the present paper, the modified screening interaction potential was adopted to investigate the dust lattice waves in dusty ring. Firstly, the influence of parameter ε on the modified screening interaction potential was analyzed; and it was found that the parameter ε has a long-range effect on the pairwise interaction between the particles. Secondly, the dispersion relations of longitudinal and transverse waves are obtained, and the effect of long-range action parameter ε, dimensionless lattice parameter α and dimensionless shielding parameter \\tilde{κ } on the dust lattice waves propagation in dusty ring are studied. Some interesting phenomena, such as the coupling of longitudinal and transverse waves, and instabilities of transverse waves are found, which are in good agreement with some previous works. Finally, the transverse wave instabilities and the relevant critical lattice parameter αc are presented and discussed.

Longitudinal links among parenting, self-presentations to peers, and the development of externalizing and internalizing symptoms in African American siblings.

PubMed

Brody, Gene H; Kim, Sooyeon; Murry, Velma McBride; Brown, Anita C

2005-01-01

A longitudinal model that linked involved-supportive parenting and siblings' ability-camouflaging self-presentations to peers with the development of externalizing and internalizing symptoms was tested with 152 pairs of first- and second-born African American siblings (mean ages 12.7 years and 10.2 years at the first wave of data collection). Three waves of data were collected at 1-year intervals. Teachers assessed siblings' externalizing symptoms, internalizing symptoms, and academic competence; siblings reported their own self-presentations and desire for peer acceptance; and mothers and siblings provided multiinformant assessments of involved-supportive parenting. Involved-supportive parenting at Wave 1 was linked with peer-directed self-presentations at Wave 2. Wave 2 self-presentations were linked indirectly with changes from Wave 1 to Wave 3 in externalizing and internalizing symptoms through their association with academic competence.

Propagation and Dissipation of MHD Waves in Coronal Holes

NASA Astrophysics Data System (ADS)

Dwivedi, B. N.

2006-11-01

bholadwivedi@gmail.com In view of the landmark result on the solar wind outflow, starting between 5 Mm and 20 Mm above the photosphere in magnetic funnels, we investigate the propagation and dissipation of MHD waves in coronal holes. We underline the importance of Alfvén wave dissipation in the magnetic funnels through the viscous and resistive plasma. Our results show that Alfvén waves are one of the primary energy sources in the innermost part of coronal holes where the solar wind outflow starts. We also consider compressive viscosity and thermal conductivity to study the propagation and dissipation of long period slow longitudinal MHD waves in polar coronal holes. We discuss their likely role in the line profile narrowing, and in the energy budget for coronal holes and the solar wind. We compare the contribution of longitudinal MHD waves with high frequency Alfvén waves.

Analytical investigation of the dynamics of tethered constellations in earth orbit

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico C.; Gullahorn, Gordon E.; Estes, Robert D.

1988-01-01

This Quarterly Report on Tethering in Earth Orbit deals with three topics: (1) Investigation of the propagation of longitudinal and transverse waves along the upper tether. Specifically, the upper tether is modeled as three massive platforms connected by two perfectly elastic continua (tether segments). The tether attachment point to the station is assumed to vibrate both longitudinally and transversely at a given frequency. Longitudinal and transverse waves propagate along the tethers affecting the acceleration levels at the elevator and at the upper platform. The displacement and acceleration frequency-response functions at the elevator and at the upper platform are computed for both longitudinal and transverse waves. An analysis to optimize the damping time of the longitudinal dampers is also carried out in order to select optimal parameters. The analytical evaluation of the performance of tuned vs. detuned longitudinal dampers is also part of this analysis. (2) The use of the Shuttle primary Reaction Control System (RCS) thrusters for blowing away a recoiling broken tether is discussed. A microcomputer system was set up to support this operation. (3) Most of the effort in the tether plasma physics study was devoted to software development. A particle simulation code has been integrated into the Macintosh II computer system and will be utilized for studying the physics of hollow cathodes.

The thermal-wave model: A Schroedinger-like equation for charged particle beam dynamics

NASA Technical Reports Server (NTRS)

Fedele, Renato; Miele, G.

1994-01-01

We review some results on longitudinal beam dynamics obtained in the framework of the Thermal Wave Model (TWM). In this model, which has recently shown the capability to describe both longitudinal and transverse dynamics of charged particle beams, the beam dynamics is ruled by Schroedinger-like equations for the beam wave functions, whose squared modulus is proportional to the beam density profile. Remarkably, the role of the Planck constant is played by a diffractive constant epsilon, the emittance, which has a thermal nature.

Modulational instability of finite-amplitude, circularly polarized Alfven waves

NASA Technical Reports Server (NTRS)

Derby, N. F., Jr.

1978-01-01

The simple theory of the decay instability of Alfven waves is strictly applicable only to a small-amplitude parent wave in a low-beta plasma, but, if the parent wave is circularly polarized, it is possible to analyze the situation without either of these restrictions. Results show that a large-amplitude circularly polarized wave is unstable with respect to decay into three waves, one longitudinal and one transverse wave propagating parallel to the parent wave and one transverse wave propagating antiparallel. The transverse decay products appear at frequencies which are the sum and difference of the frequencies of the parent wave and the longitudinal wave. The decay products are not familiar MHD modes except in the limit of small beta and small amplitude of the parent wave, in which case the decay products are a forward-propagating sound wave and a backward-propagating circularly polarized wave. In this limit the other transverse wave disappears. The effect of finite beta is to reduce the linear growth rate of the instability from the value suggested by the simple theory. Possible applications of these results to the theory of the solar wind are briefly touched upon.

Contrasts Between Young Males Dying by Suicide, Those Dying From Other Causes and Those Still Living: Observations From the National Longitudinal Survey of Adolescent to Adult Health.

PubMed

Feigelman, William; Joiner, Thomas; Rosen, Zohn; Silva, Caroline; Mueller, Anna S

2016-07-02

Utilizing Add Health longitudinal data, we compared 21 male suicide casualties to 10,101 living respondents identifying suicide correlates. 21 suicide decedents completed surveys in 1994/1995 (Wave 1) and 11 completed at Wave 3; responses were compared with Chi-square and oneway ANOVA tests. Suicide decedents were prone to higher delinquency and fighting at Wave 1, but not at Wave 3. At Wave 1 suicide decedents remained undistinguished from living respondents in depression, self-esteem, and drug uses. Yet, after Wave 3, the 11 respondents dying by suicide showed significantly higher depression, drug use and lower self-esteem. Delinquency trends can readily understood, but more complex causes are needed to account for unexpected changes in self-esteem, depression and drug uses.

Longitudinal Waves Organize and Control Plants and Other Life

NASA Astrophysics Data System (ADS)

Wagner, Orvin E.

2002-04-01

Since the discovery of longitudinal waves in plants (W-waves) in 1988 I have taken data related to influences of these waves. These data include spacings between structures on plants, sap flow data, electrical data from probes traceable to effects produced by these waves, data related to the influences of gravity, data related to these waves traveling between plants and on and on. All of the data suggest that these waves provide a basis for a unified theory for plant growth and development. They likely provide a basis for growth and development for all life. The wave influences are present on the microscopic level in live plants but may not show in the microscopic pieces of material often scrutinized by the usual researcher. It is this author's conclusion that the waves mentioned are important in all life and provide what we call life which has been so difficult to pinpoint in previous work. The waves show in dead material but generally are of a much smaller amplitude than in resonating live material. In the wave theory one might compare something alive to a properly operating laser. See the

Mode-converted diffuse ultrasonic backscatter.

PubMed

Hu, Ping; Kube, Christopher M; Koester, Lucas W; Turner, Joseph A

2013-08-01

Diffuse ultrasonic backscatter describes the scattering of elastic waves from interfaces within heterogeneous materials. Previously, theoretical models have been developed for the diffuse backscatter of longitudinal-to-longitudinal (L-L) wave scattering within polycrystalline materials. Following a similar formalism, a mode-conversion scattering model is presented here to quantify the component of an incident longitudinal wave that scatters and is converted to a transverse (shear) wave within a polycrystalline sample. The model is then used to fit experimental measurements associated with a pitch-catch transducer configuration performed using a sample of 1040 steel. From these measurements, an average material correlation length is determined. This value is found to be in agreement with results from L-L scattering measurements and is on the order of the grain size as determined from optical micrographs. Mode-converted ultrasonic backscatter is influenced much less by the front-wall reflection than an L-L measurement and it provides additional microstructural information that is not accessible in any other manner.

The mediating role of perceived peer support in the relation between quality of attachment and internalizing problems in adolescence: a longitudinal perspective.

PubMed

Pace, Ugo; Zappulla, Carla; Di Maggio, Rosanna

2016-10-01

The study was aimed to verify, from a longitudinal perspective, whether perceived peer support would mediate the relationship between attachment and internalizing problems. Longitudinal participants included 482 adolescents (245 boys) aged 14-15 years in Wave 1 and 17-18 years in Wave 2. Participants in Wave 1 completed the Relationship Questionnaire, and those in Wave 2 completed the Social Support Questionnaire and the Youth Self-Report. Results showed that secure attachment positively predicted high levels of perceived peer support and negatively predicted internalizing problems, whereas fearful and preoccupied attachment negatively predicted perceived peer support and positively predicted internalizing problems. The mediation models showed that perceived peer support partially mediated the relationship between secure attachment and internalizing problems as well as between preoccupied attachment and internalizing problems and between fearful attachment and internalizing problems. Our results confirm the role of subjective perception of peer support in contributing to the prediction of internalizing problems beyond attachment styles.

Testing Reciprocal Longitudinal Relations between Peer Victimization and Depressive Symptoms in Young Adolescents

ERIC Educational Resources Information Center

Tran, Cong V.; Cole, David A.; Weiss, Bahr

2012-01-01

A 2-wave longitudinal study of young adolescents was used to test whether peer victimization predicts depressive symptoms, depressive symptoms predict peer victimization, or the 2 constructs show reciprocal relations. Participants were 598 youths in Grades 3 through 6, ages 8 to 14 (M = 10.9, SD = 1.2) at Wave 1. The sample was 50.7% female and…

Longitudinal Surveys of Australian Youth (LSAY) 2003 Cohort: Wave 9 (2011)--Frequency Tables. Technical Report 76B

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This series of documents provides supporting information for the LSAY data set of the 2003 cohort at wave 9 (2011). This document presents the frequency tables for…

Longitudinal Surveys of Australian Youth (LSAY) 2006 Cohort: Wave 6 (2011)--Frequency Tables. Technical Report 75B

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. This series of documents provides supporting information for the LSAY data set of the 2006 cohort at wave 6 (2011). This document presents the frequency tables for…

Attrition in a Large Scale Longitudinal Study of the Elderly: The Role of Health-Status Variables.

ERIC Educational Resources Information Center

Horgas, Ann L.; And Others

In a longitudinal study, subject attrition constitutes a potential threat to the usefulness of data collected from subjects remaining in later waves of the study. If attrition is selective, then the sample at later waves of the study may be representative of a different population than that represented at the outset of the study. This study…

Relationship between longitudinal stress wave transit time and moisture content of lumber during kiln-drying

Treesearch

William T. Simpson; Xiping. Wang

2001-01-01

The relationship between longitudinal stress wave transit time and wood moisture content (MC) was examined as a potential means of estimating MC control points in dry kiln schedules for lumber. A linear relationship was found between the relative transit time and the average MC of sugar maple and ponderosa pine boards dried according to typical kiln schedules.

Different experimental results for the influence of immersion angle on the resonant frequency of a quartz crystal microbalance in a liquid phase: with a comment.

PubMed

Shen, Dazhong; Kang, Qi; Li, Xiaoyu; Cai, Hongmei; Wang, Yuandong

2007-06-19

This paper presents different experimental results of the influence of an immersion angle (theta, the angle between the surface of a quartz crystal resonator and the horizon) on the resonant frequency of a quartz crystal microbalance (QCM) sensor exposed one side of its sensing surfaces to liquid. The experimental results show that the immersion angle is an added factor that may influence the frequency of the QCM sensor. This type of influence is caused by variation of the reflection conditions of the longitudinal wave between the QCM sensor and the walls of the detection cell. The frequency shifts, measured by varying theta, are related to the QCM sensor used. When a QCM sensor with a weak longitudinal wave is used, its resonant frequency is nearly independent of theta. But, if a QCM sensor with a strong longitudinal wave is employed, the immersion angle is a potential error source for the measurements performed on the QCM sensor. When the reflection conditions of the longitudinal wave are reduced, the influence of theta on the resonant frequency of the QCM sensor is negligible. The slope of the plot of frequency shifts (deltaF) versus (rho eta)(1/2), the square root of the product of solution density (rho) and viscosity (eta), may be influenced by theta in a single experiment for the QCM sensor with a strong longitudinal wave in low viscous liquids, which can however, be effectively weakened by using the averaged values of reduplicated experiments. In solutions with a large (rho eta)(1/2) region (0-55 wt% sucrose solution as an example, with rho value from 1.00 to 1.26 g cm(-3) and eta value from 0.01 to 0.22 g cm(-1) s(-1), respectively), the slope of the plot of deltaF versus (rho eta)(1/2) is independent of theta even for the QCM sensor with a strong longitudinal wave in a single experiment. The influence of theta on the resonant frequency of the QCM sensor should be taken into consideration in its applications in liquid phase.

Lamb waves increase sensitivity in nondestructive testing

NASA Technical Reports Server (NTRS)

Di Novi, R.

1967-01-01

Lamb waves improve sensitivity and resolution in the detection of small defects in thin plates and small diameter, thin-walled tubing. This improvement over shear waves applies to both longitudinal and transverse flaws in the specimens.

Effects of laser source parameters on the generation of narrow band and directed laser ultrasound

NASA Technical Reports Server (NTRS)

Spicer, James B.; Deaton, John B., Jr.; Wagner, James W.

1992-01-01

Predictive and prescriptive modeling of laser arrays is performed to demonstrate the effects of the extension of array elements on laser array performance. For a repetitively pulsed laser source (the temporal laser array), efficient frequency compression is best achieved by detecting longitudinal waves off-epicenter in plates where the source size and shape directly influence the longitudinal wave shape and duration; the longitudinal array may be tailored for a given repetition frequency to yield efficient overtone energy compression into the fundamental frequency band. For phased arrays, apparent array directivity is heavily influenced by array element size.

An equivalent viscoelastic model for rock mass with parallel joints

NASA Astrophysics Data System (ADS)

Li, Jianchun; Ma, Guowei; Zhao, Jian

2010-03-01

An equivalent viscoelastic medium model is proposed for rock mass with parallel joints. A concept of "virtual wave source (VWS)" is proposed to take into account the wave reflections between the joints. The equivalent model can be effectively applied to analyze longitudinal wave propagation through discontinuous media with parallel joints. Parameters in the equivalent viscoelastic model are derived analytically based on longitudinal wave propagation across a single rock joint. The proposed model is then verified by applying identical incident waves to the discontinuous and equivalent viscoelastic media at one end to compare the output waves at the other end. When the wavelength of the incident wave is sufficiently long compared to the joint spacing, the effect of the VWS on wave propagation in rock mass is prominent. The results from the equivalent viscoelastic medium model are very similar to those determined from the displacement discontinuity method. Frequency dependence and joint spacing effect on the equivalent viscoelastic model and the VWS method are discussed.

Longitudinal association of obesity, metabolic syndrome and diabetes with risk of elevated aminotransferase levels in a cohort of Mexican health workers.

PubMed

Flores, Yvonne N; Auslander, Allyn; Crespi, Catherine M; Rodriguez, Michael; Zhang, Zuo-Feng; Durazo, Francisco; Salmerón, Jorge

2016-05-01

In Mexico, chronic liver disease have been increasingly found along with the rapidly growing prevalence of obesity, diabetes and metabolic syndrome (MS). We aimed to investigate the longitudinal association between these three factors and risk of elevated alanine aminotransferase (ALT) levels (>40 U/L), a marker for liver damage, in a cohort of Mexican adults. Data were obtained from two separate waves of the Mexican Health Worker Cohort Study: Wave 1 (2004-2006) and Wave 2 (2011-2013). Unconditional logistic regression models were employed to determine the cross-sectional and longitudinal association between these risk factors and elevated ALT levels. The prevalence of elevated ALT was significantly higher among men, individuals aged under 60 years, those who were overweight or obese, diabetic, with MS or heavy/binge drinkers. The longitudinal results indicated that weight gain between waves that resulted in a change in body mass index, along with remaining overweight or obese, were significantly associated with an increased risk of elevated ALT levels. A significantly increased risk of developing elevated ALT was also observed among those who acquired diabetes or MS from Wave 1 to Wave 2. Weight gain and acquiring diabetes or MS are associated with a significant risk of having elevated ALT. These results, within the context of the rapid increase in global obesity rates, call urgently for programs to help to prevent chronic liver disease. © 2016 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

Bulk Nonlinear Elastic Strain Waves in a Bilayer Coaxial Cylindrical Rod

NASA Astrophysics Data System (ADS)

Gula, I. A.; Samsonov, A. M.

2017-12-01

The problem of the propagation of long nonlinear elastic strain waves in a bilayer coaxial cylindrical rod with an ideal contact between the layers has been considered. Expressions for transverse displacements through longitudinal displacements have been derived. The former satisfies free boundary conditions and continuity conditions for displacements and stresses at the interlayer interface with the desired accuracy. It has been shown how these expressions generalize the well-known plane-section and Love hypotheses for an isotropic homogeneous rod. An equation for the propagation of a nonlinearly elastic strain longitudinal wave has been derived, and its particular solution in the form of a solitary traveling wave has been studied.

Elastic properties of aspirin in its crystalline and glassy phases studied by micro-Brillouin scattering

NASA Astrophysics Data System (ADS)

Ko, Jae-Hyeon; Lee, Kwang-Sei; Ike, Yuji; Kojima, Seiji

2008-11-01

The acoustic waves propagating along the direction perpendicular to the (1 0 0) cleavage plane of aspirin crystal were investigated using micro-Brillouin spectroscopy from which C11, C55 and C66 were obtained. The temperature dependence of the longitudinal acoustic waves could be explained by normal anharmonic lattice models, while the transverse acoustic waves showed an abnormal increase in the hypersonic attenuation at low temperatures indicating their coupling to local remnant dynamics. The sound velocity as well as the attenuation of the longitudinal acoustic waves of glassy aspirin showed a substantial change at ˜235 K confirming a transition from glassy to supercooled liquid state in vitreous aspirin.

Health and social exclusion in older age: evidence from Understanding Society, the UK household longitudinal study.

PubMed

Sacker, Amanda; Ross, Andy; MacLeod, Catherine A; Netuveli, Gopal; Windle, Gill

2017-07-01

Social exclusion of the elderly is a key policy focus but evidence on the processes linking health and social exclusion is hampered by the variety of ways that health is used in social exclusion research. We investigated longitudinal associations between health and social exclusion using an analytical framework that did not conflate them. Data employed in this study came from 4 waves of Understanding Society, the UK Household Longitudinal Study 2009-2013. The sample comprised all adults who took part in all 4 waves, were 65 years or more in Wave 3, and had complete data on our variables of interest for each analysis. We used linear regression to model the relationship between Wave 2/3 social exclusion and Wave1-2 health transitions (N=4312) and logistic regression to model the relationship between Wave2/3 social exclusion and Wave 4 health states, conditional on Wave 3 health (N=4244). There was a dose-response relationship between poor health in Waves 1 and 2 and later social exclusion. Use of a car, mobile phone and the internet moderated the association between poor health and social exclusion. Given the health status in Wave 3, those who were more socially excluded had poorer outcomes on each of the three domains of health in Wave 4. Use of the internet and technology protected older adults in poor health from social exclusion. Age-friendly hardware and software design might have public health benefits. 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/.

Longitudinal spread of mechanical excitation through tectorial membrane traveling waves

PubMed Central

Sellon, Jonathan B.; Farrahi, Shirin; Ghaffari, Roozbeh; Freeman, Dennis M.

2015-01-01

The mammalian inner ear separates sounds by their frequency content, and this separation underlies important properties of human hearing, including our ability to understand speech in noisy environments. Studies of genetic disorders of hearing have demonstrated a link between frequency selectivity and wave properties of the tectorial membrane (TM). To understand these wave properties better, we developed chemical manipulations that systematically and reversibly alter TM stiffness and viscosity. Using microfabricated shear probes, we show that (i) reducing pH reduces TM stiffness with little change in TM viscosity and (ii) adding PEG increases TM viscosity with little change in TM stiffness. By applying these manipulations in measurements of TM waves, we show that TM wave speed is determined primarily by stiffness at low frequencies and by viscosity at high frequencies. Both TM viscosity and stiffness affect the longitudinal spread of mechanical excitation through the TM over a broad range of frequencies. Increasing TM viscosity or decreasing stiffness reduces longitudinal spread of mechanical excitation, thereby coupling a smaller range of best frequencies and sharpening tuning. In contrast, increasing viscous loss or decreasing stiffness would tend to broaden tuning in resonance-based TM models. Thus, TM wave and resonance mechanisms are fundamentally different in the way they control frequency selectivity. PMID:26438861

Construction strength analysis of landing craft tank conversion to passenger ship using finite element method

NASA Astrophysics Data System (ADS)

Nurul Misbah, Mohammad; Setyawan, Dony; Murti Dananjaya, Wisnu

2018-03-01

This research aims to determine the longitudinal strength of passenger ship which was converted from Landing Craft Tank with 54 m of length as stated by BKI (Biro Klasifikasi Indonesia / Indonesian Classification Bureau). Verification of strength value is done to 4 (four) loading conditions which are (1) empty load condition during sagging wave, (2) empty load condition during hogging wave, (3) full load condition during sagging wave and (4) full load condition during hogging wave. Analysis is done using Finite Element Analysis (FEA) software by modeling the entire part of passenger ship and its loading condition. The back and upfront part of ship centerline were used as the boundary condition. From that analysis it can be concluded that the maximum stress for load condition (1) is 72,393 MPa, 74,792 MPa for load condition (2), 129,92 MPa for load condition (3), and 132,4 MPa for load condition (4). Longitudinal strength of passenger ship fulfilled the criteria of empty load condition having smaller stress value than allowable stress which is 90 MPa, and during full load condition with smaller stress value than allowable stress which is 150 MPa. Analysis on longitudinal strength comparison with entire ship plate thickness variation of ± 2 mm from initial plate was also done during this research. From this research it can be concluded that plate thickness reduction causes the value of longitudinal strength to decrease, while plate thickness addition causes the value of longitudinal strength to increase.

Rigorous approaches to tether dynamics in deployment and retrieval

NASA Technical Reports Server (NTRS)

Antona, Ettore

1987-01-01

Dynamics of tethers in a linearized analysis can be considered as the superposition of propagating waves. This approach permits a new way for the analysis of tether behavior during deployment and retrieval, where a tether is composed by a part at rest and a part subjected to propagation phenomena, with the separating section depending on time. The dependence on time of the separating section requires the analysis of the reflection of the waves travelling toward the part at rest. Such a reflection generates a reflected wave, whose characteristics are determined. The propagation phenomena of major interest in a tether are transverse waves and longitudinal waves, all mathematically modelled by the vibrating chord equations, if the tension is considered constant along the tether. An interesting problem also considered is concerned with the dependence of the tether tension from the longitudinal position, due to microgravity, and the influence of this dependence on the propagation waves.

Focusing of Shear Shock Waves

NASA Astrophysics Data System (ADS)

Giammarinaro, Bruno; Espíndola, David; Coulouvrat, François; Pinton, Gianmarco

2018-01-01

Focusing is a ubiquitous way to transform waves. Recently, a new type of shock wave has been observed experimentally with high-frame-rate ultrasound: shear shock waves in soft solids. These strongly nonlinear waves are characterized by a high Mach number, because the shear wave velocity is much slower, by 3 orders of magnitude, than the longitudinal wave velocity. Furthermore, these waves have a unique cubic nonlinearity which generates only odd harmonics. Unlike longitudinal waves for which only compressional shocks are possible, shear waves exhibit cubic nonlinearities which can generate positive and negative shocks. Here we present the experimental observation of shear shock wave focusing, generated by the vertical motion of a solid cylinder section embedded in a soft gelatin-graphite phantom to induce linearly vertically polarized motion. Raw ultrasound data from high-frame-rate (7692 images per second) acquisitions in combination with algorithms that are tuned to detect small displacements (approximately 1 μ m ) are used to generate quantitative movies of gel motion. The features of shear shock wave focusing are analyzed by comparing experimental observations with numerical simulations of a retarded-time elastodynamic equation with cubic nonlinearities and empirical attenuation laws for soft solids.

A new point contact surface acoustic wave transducer for measurement of acoustoelastic effect of polymethylmethacrylate.

PubMed

Lee, Yung-Chun; Kuo, Shi Hoa

2004-01-01

A new acoustic transducer and measurement method have been developed for precise measurement of surface wave velocity. This measurement method is used to investigate the acoustoelastic effects for waves propagating on the surface of a polymethylmethacrylate (PMMA) sample. The transducer uses two miniature conical PZT elements for acoustic wave transmitter and receiver on the sample surface; hence, it can be viewed as a point-source/point-receiver transducer. Acoustic waves are excited and detected with the PZT elements, and the wave velocity can be accurately determined with a cross-correlation waveform comparison method. The transducer and its measurement method are particularly sensitive and accurate in determining small changes in wave velocity; therefore, they are applied to the measurement of acoustoelastic effects in PMMA materials. Both the surface skimming longitudinal wave and Rayleigh surface wave can be simultaneously excited and measured. With a uniaxial-loaded PMMA sample, both acoustoelastic effects for surface skimming longitudinal wave and Rayleigh waves of PMMA are measured. The acoustoelastic coefficients for both types of surface wave motions are simultaneously determined. The transducer and its measurement method provide a practical way for measuring surface stresses nondestructively.

Very small IF resonator filters using reflection of shear horizontal wave at free edges of substrate.

PubMed

Kadota, Michio; Ago, Junya; Horiuchi, Hideya; Ikeura, Mamoru

2002-09-01

A shear horizontal (SH) wave has the characteristic of complete reflection at the free edges of a substrate with a large dielectric constant. A conventional surface acoustic wave (SAW) resonator filter requires reflectors consisting of numerous grating fingers on both sides of interdigital transducers (IDTs). On the contrary, it is considered that small-sized and low loss resonator filters without reflectors consisting of grating fingers can be realized by exploiting this characteristic of the SH wave or the Bleustein-Gulyaev-Shimizu (BGS) wave. There are two types of resonator filters: transversely coupled and longitudinally coupled. No transversely coupled filters (neither conventional nor edge-reflection) using the SH wave on a single-crystal substrate have been realized until now, because two transverse modes (symmetrical and asymmetrical modes) are not easily coupled. However, the authors have realized small low loss transversely coupled resonator filters in the range of 25 to 52 MHz using edge reflections of the BGS wave on piezoelectric ceramic (PZT: Pb(Zr,Ti)O3) substrates for the first time by developing methods by which the two transverse modes could be coupled. On the other hand, longitudinally coupled resonator filters using edge reflection of the SH or BGS wave always have large spurious responses because of the even modes in the out-of-band range, because the frequencies of even modes do not coincide with the nulls of the frequency spectra of the IDTs. Consequently, longitudinally coupled resonator filters using the edge reflection of the SH wave have not been realized. By developing a method of reducing the spurious responses without increasing of the insertion loss, the authors have realized small low loss longitudinally coupled resonator filters in the range of 40 to 190 MHz using edge reflection of BGS or SH waves on PZT or 36 degrees-rotated-Y X-propagation LiTaO3 substrates for the first time. Despite being intermediate frequency (IF) filters, their package (3 x 3 x 1.03 mm3) sizes are as small as those of radio frequency (RF) SAW filters.

Social Media Use, Social Media Stress, and Sleep: Examining Cross-Sectional and Longitudinal Relationships in Adolescents.

PubMed

van der Schuur, Winneke A; Baumgartner, Susanne E; Sumter, Sindy R

2018-01-09

There are concerns that social media (SM) use and SM stress may disrupt sleep. However, evidence on both the cross-sectional and longitudinal relationships is limited. Therefore, the main aim of this study is to address this gap in the literature by examining the cross-sectional and longitudinal relationships between SM use, SM stress, and sleep (i.e., sleep latency and daytime sleepiness) in adolescents. In total, 1,441 adolescents 11-15 years, 51% boys) filled out a survey in at least one of three waves that were three to four months apart (N Wave1  = 1,241; N Wave2  = 1,216; N Wave3  = 1,103). Cross-sectionally, we found that SM use and SM stress were positively related to sleep latency and daytime sleepiness. However, when examined together, SM use was not a significant predictor of sleep latency and daytime sleepiness above the effects of SM stress. The longitudinal findings showed that SM stress was positively related to subsequent sleep latency and daytime sleepiness, but only among girls. Our findings stress that it is important to focus on how adolescents perceive and cope with their SM use, instead of focusing on the mere frequency of SM use.

Evaluation of interlayer interfacial stiffness and layer wave velocity of multilayered structures by ultrasonic spectroscopy.

PubMed

Ishii, Yosuke; Biwa, Shiro

2014-07-01

An ultrasonic evaluation procedure for the interlayer interfacial normal stiffness and the intralayer longitudinal wave velocity of multilayered plate-like structures is proposed. Based on the characteristics of the amplitude reflection spectrum of ultrasonic wave at normal incidence to a layered structure with spring-type interlayer interfaces, it is shown that the interfacial normal stiffness and the longitudinal wave velocity in the layers can be simultaneously evaluated from the frequencies of local maxima and minima of the spectrum provided that all interfaces and layers have the same properties. The effectiveness of the proposed procedure is investigated from the perspective of the sensitivity of local extremal frequencies of the reflection spectrum. The feasibility of the proposed procedure is also investigated when the stiffness of each interface is subjected to small random fluctuations about a certain average value. The proposed procedure is applied to a 16-layered cross-ply carbon-fiber-reinforced composite laminate. The normal stiffness of resin-rich interfaces and the longitudinal wave velocity of plies in the thickness direction evaluated from the experimental reflection spectrum are shown to be consistent with simple theoretical estimations.

Properties of Longitudinal Electromagnetic Oscillations in Metals and Their Excitation at Planar and Spherical Surfaces.

PubMed

Datsyuk, Vitaly V; Pavlyniuk, Oleg R

2017-12-01

The common definition of the spatially dispersive permittivity is revised. The response of the degenerate electron gas on an electric field satisfying the vector Helmholtz equation is found with a solution to the Boltzmann equation. The calculated longitudinal dielectric function coincides with that obtained by Klimontovich and Silin in 1952 and Lindhard in 1954. However, it depends on the square of the wavenumber, a parameter of the vector Helmholtz equation, but not the wave vector of a plane electromagnetic wave. This new concept simplifies simulation of the nonlocal effects, for example, with a generalized Lorents-Mie theory, since no Fourier transforms should be made. The Fresnel coefficients are generalized allowing for excitation of the longitudinal electromagnetic waves. To verify the theory, the extinction spectra for silver and gold nanometer-sized spheres are calculated. For these particles, the generalized Lorents-Mie theory gives the blue shift and broadening of the plasmon resonance which are in excellent agreement with experimental data. In addition, the nonlocal theory explains vanishing of the plasmon resonance observed for gold spheres with diameters less than or equal to 2 nm. The calculations using the Klimontovich-Silin-Lindhard and hydrodynamic dielectric functions for silver are found to give close results at photon energies from 3 to 4 eV. We show that the absolute values of the wavenumbers of the longitudinal waves in solids are much higher than those of the transverse waves.

Properties of Longitudinal Electromagnetic Oscillations in Metals and Their Excitation at Planar and Spherical Surfaces

NASA Astrophysics Data System (ADS)

Datsyuk, Vitaly V.; Pavlyniuk, Oleg R.

2017-08-01

The common definition of the spatially dispersive permittivity is revised. The response of the degenerate electron gas on an electric field satisfying the vector Helmholtz equation is found with a solution to the Boltzmann equation. The calculated longitudinal dielectric function coincides with that obtained by Klimontovich and Silin in 1952 and Lindhard in 1954. However, it depends on the square of the wavenumber, a parameter of the vector Helmholtz equation, but not the wave vector of a plane electromagnetic wave. This new concept simplifies simulation of the nonlocal effects, for example, with a generalized Lorents-Mie theory, since no Fourier transforms should be made. The Fresnel coefficients are generalized allowing for excitation of the longitudinal electromagnetic waves. To verify the theory, the extinction spectra for silver and gold nanometer-sized spheres are calculated. For these particles, the generalized Lorents-Mie theory gives the blue shift and broadening of the plasmon resonance which are in excellent agreement with experimental data. In addition, the nonlocal theory explains vanishing of the plasmon resonance observed for gold spheres with diameters less than or equal to 2 nm. The calculations using the Klimontovich-Silin-Lindhard and hydrodynamic dielectric functions for silver are found to give close results at photon energies from 3 to 4 eV. We show that the absolute values of the wavenumbers of the longitudinal waves in solids are much higher than those of the transverse waves.

Acoustic and mechanical properties of renal calculi: implications in shock wave lithotripsy.

PubMed

Chuong, C J; Zhong, P; Preminger, G M

1993-12-01

The acoustic and mechanical properties of renal calculi dictate how a stone interacts with the mechanical forces produced by shock wave lithotripsy; thus, these properties are directly related to the success of the treatment. Using an ultrasound pulse transmission technique, we measured both longitudinal and transverse (or shear) wave propagation speeds in nine groups of renal calculi with different chemical compositions. We also measured stone density using a pycnometer based on Archimedes' principle. From these measurements, we calculated wave impedance and dynamic mechanical properties of the renal stones. Calcium oxalate monohydrate and cystine stones had higher longitudinal and transverse wave speeds, wave impedances, and dynamic moduli (bulk modulus, Young's modulus, and shear modulus), suggesting that these stones are more difficult to fragment. Phosphate stones (carbonate apatite and magnesium ammonium phosphate hydrogen) were found to have lower values of these properties, suggesting they are more amenable to shock wave fragmentation. These data provide a physical explanation for the significant differences in stone fragility observed clinically.

Polarizations of gravitational waves in Horndeski theory

NASA Astrophysics Data System (ADS)

Hou, Shaoqi; Gong, Yungui; Liu, Yunqi

2018-05-01

We analyze the polarization content of gravitational waves in Horndeski theory. Besides the familiar plus and cross polarizations in Einstein's General Relativity, there is one more polarization state which is the mixture of the transverse breathing and longitudinal polarizations. The additional mode is excited by the massive scalar field. In the massless limit, the longitudinal polarization disappears, while the breathing one persists. The upper bound on the graviton mass severely constrains the amplitude of the longitudinal polarization, which makes its detection highly unlikely by the ground-based or space-borne interferometers in the near future. However, pulsar timing arrays might be able to detect the polarization excited by the massive scalar field. Since additional polarization states appear in alternative theories of gravity, the measurement of the polarizations of gravitational waves can be used to probe the nature of gravity. In addition to the plus and cross states, the detection of the breathing polarization means that gravitation is mediated by massless spin 2 and spin 0 fields, and the detection of both the breathing and longitudinal states means that gravitation is propagated by the massless spin 2 and massive spin 0 fields.

Ultrasonic attenuation and velocity in AS/3501-6 graphite/epoxy fiber composite

NASA Technical Reports Server (NTRS)

Williams, J. H., Jr.; Nayebhashemi, H.; Lee, S. S.

1979-01-01

The ultrasonic group velocity and attenuation were measured as a function of frequency for longitudinal and shear waves in the epoxy matrix (3501-6) and in the principal directions of the unidirectional graphite/epoxy composite (AS/3501-6). Tests were conducted in the frequency ranges 0.25 Mz to 14 MHz and 0.5 Mz to 3 MHz for longitudinal and shear wave modes, respectively. The attenuation increased with frequency for all wave modes, but the group velocity was independent of frequency for all wave modes. The effects of pressure and couplant at the transducer-specimen interface were studied and it was found that for each transducer type there exists a frequency dependent 'saturation pressure' corresponding to the maximum output signal amplitude.

Investigation of longitudinal control system for a small hydrofoil boat

NASA Technical Reports Server (NTRS)

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.

Evaluation of the acoustoelectric effect in the thickness direction of c-plane ZnO single crystals by Brillouin scattering

NASA Astrophysics Data System (ADS)

Tomita, Shota; Yanagitani, Takahiko; Takayanagi, Shinji; Ichihashi, Hayato; Shibagaki, Yoshiaki; Hayashi, Hiromichi; Matsukawa, Mami

2017-06-01

Longitudinal wave velocity dispersion in ZnO single crystals, owing to the acoustoelectric effect, has been investigated by Brillouin scattering. The resistivity dependence of the longitudinal wave velocity in a c-plane ZnO single crystal was theoretically estimated and experimentally investigated. Velocity dispersion owing to the acoustoelectric effect was observed in the range 0.007-10 Ωm. The observed velocity dispersion shows a similar tendency to the theoretical estimation and gives the piezoelectric stiffened and unstiffened wave velocities. However, the measured dispersion curve shows a characteristic shift from the theoretical curve. One possible reason is the carrier mobility in the sample, which could be lower than the reported value. The measurement data gave the piezoelectric stiffened and unstiffened longitudinal wave velocities, from which the electromechanical coupling coefficient k33 was determined. The value of k33 is in good agreement with reported values. This method is promising for noncontact evaluation of electromechanical coupling. In particular, it could be for evaluation of the unknown piezoelectricity in the thickness direction of semiconductive materials and film resonators.

Longitudinal impact of the project PATHS on adolescent risk behavior: what happened after five years?

PubMed

Shek, Daniel T L; Yu, Lu

2012-01-01

The present study investigated the longitudinal impact of the Project PATHS, a large-scale curriculum-based positive youth development program in Hong Kong, on the development of adolescents' risk behavior over a period of five years. Using a longitudinal randomized controlled design, eight waves of data were collected from 19 experimental schools in which students participated in the Project PATHS (N = 2,850 at Wave 8) and 24 control schools without joining the Project PATHS (N = 3,640 at Wave 8). At each wave, students responded to measures assessing their current risk behaviors, including delinquency, use of different types of drug, and their intentions of participating in risk behaviors in the future. Results demonstrated that adolescents receiving the program exhibited significantly slower increases in delinquent behaviors and substance use as compared to the control participants. During two years after the completion of the program, differences in youth risk behaviors in the two groups still existed. These results suggest that the Project PATHS has long-term effect in preventing adolescent problem behavior through promoting positive youth development.

The Heritability of Insomnia Progression during Childhood/Adolescence: Results from a Longitudinal Twin Study

PubMed Central

Barclay, Nicola L.; Gehrman, Philip R.; Gregory, Alice M.; Eaves, Lindon J.; Silberg, Judy L.

2015-01-01

Study Objectives: To determine prevalence and heritability of insomnia during middle/late childhood and adolescence; examine longitudinal associations in insomnia over time; and assess the extent to which genetic and environmental factors on insomnia remain stable, or whether new factors come into play, across this developmental period. Design: Longitudinal twin study. Setting: Academic medical center. Patients or Participants: There were 739 complete monozygotic twin pairs (52%) and 672 complete dizygotic twin pairs (48%) initially enrolled and were followed up at three additional time points (waves). Mode ages at each wave were 8, 10, 14, and 15 y (ages ranged from 8–18 y). Interventions: None. Measurements and Results: Clinical ratings of insomnia symptoms were assessed using the Child and Adolescent Psychiatric Assessment (CAPA) by trained clinicians, and rated according to Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition—Revised criteria for presence of “clinically significant insomnia,” over four sequential waves. Insomnia symptoms were prevalent but significantly decreased across the four waves (ranging from 16.6% to 31.2%). “Clinically significant insomnia” was moderately heritable at all waves (h2 range = 14% to 38%), and the remaining source of variance was the nonshared environment. Multivariate models indicated that genetic influences at wave 1 contributed to insomnia at all subsequent waves, and that new genetic influences came into play at wave 2, which further contributed to stability of symptoms. Nonshared environmental influences were time-specific. Conclusion: Insomnia is prevalent in childhood and adolescence, and is moderately heritable. The progression of insomnia across this developmental time period is influenced by stable as well as new genetic factors that come into play at wave 2 (modal age 10 y). Molecular genetic studies should now identify genes related to insomnia progression during childhood and adolescence. Citation: Barclay NL, Gehrman PR, Gregory AM, Eaves LJ, Silberg JL. The heritability of insomnia progression during childhood/adolescence: results from a longitudinal twin study. SLEEP 2015;38(1):109–118. PMID:25325458

Relationship between stress wave velocities of green and dry veneer

Treesearch

Brian K. Brashaw; Xiping Wang; Robert J. Ross; Roy F. Pellerin

2004-01-01

This paper evaluates the relationship between the stress wave velocities of green and dry southern pine and Douglas-fir veneers. A commercial stress wave timer and a laboratory signal analysis system were used to measure the transit time required for an induced stress wave to travel the longitudinal length of each veneer. Stress wave transit times were measured in the...

Elastic solitons in delaminated bars: splitting leads to fission

NASA Astrophysics Data System (ADS)

Samsonov, A. M.; Dreiden, G. V.; Khusnutdinova, K. R.; Semenova, I. V.

2008-06-01

Recent theoretical and successful experimental studies confirmed existence and demonstrated main properties of bulk strain solitary waves in nonlinearly elastic solid wave guides. Our current research is devoted to nonlinear wave processes in layered elastic wave guides with inhomogeneities modelling delamination. We present first theoretical and experimental results showing the influence of delamination on the parameters of the longitudinal strain solitary wave.

Reproducing an Early-20th-Century Wave Machine

ERIC Educational Resources Information Center

Daffron, John A.; Greenslade, Thomas B., Jr.

2016-01-01

Physics students often have problems understanding waves. Over the years numerous mechanical devices have been devised to show the propagation of both transverse and longitudinal waves (Ref. 1). In this article an updated version of an early-20th-century transverse wave machine is discussed. The original, Fig. 1, is at Creighton University in…

Nondestructive evaluation of green wood using stress wave and transverse vibration techniques

Treesearch

Udaya B. Halabe; Gangadhar M. Bidigalu; Hota V.S. GangaRao; Robert J. Ross

1997-01-01

Longitudinal stress wave and transverse vibration nondestructive testing (NDT) techniques have proven to be accurate means of evaluating the quality of wood based products. Researchers have found strong relationships between stress wave and transverse vibration parameters (e.g., wave velocity and modulus of elasticity predicted using NDT measurements) with the actual...

Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 1: Basic theory.

PubMed

Berkouk, K; Carpenter, P W; Lucey, A D

2003-12-01

Our work is motivated by ideas about the pathogenesis of syringomyelia. This is a serious disease characterized by the appearance of longitudinal cavities within the spinal cord. Its causes are unknown, but pressure propagation is probably implicated. We have developed an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. This is intended as a simple model of the intraspinal cerebrospinal-fluid system. Our approach is based on the classic theory for the propagation of longitudinal waves in single, fluid-filled, elastic tubes. We show that for small-amplitude waves the governing equations reduce to the classic wave equation. The wave speed is found to be a strong function of the ratio of the tubes' cross-sectional areas. It is found that the leading edge of a transmural pressure pulse tends to generate compressive waves with converging wave fronts. Consequently, the leading edge of the pressure pulse steepens to form a shock-like elastic jump. A weakly nonlinear theory is developed for such an elastic jump.

Simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament induced by a single shock wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yuandeng; Liu, Ying D.; Chen, P. F.

2014-11-10

We present the first stereoscopic and Doppler observations of simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament launched by a single shock wave. Using Hα Doppler observations, we derive the three-dimensional oscillation velocities at different heights along the prominence axis. The results indicate that the prominence has a larger oscillation amplitude and damping time at higher altitude, but the periods at different heights are the same (i.e., 13.5 minutes). This suggests that the prominence oscillates like a linear vertical rigid body with one end anchored on the Sun. One of the filaments showsmore » weak transverse oscillation after the passing of the shock, which is possibly due to the low altitude of the filament and the weakening (due to reflection) of the shock wave before the interaction. Large-amplitude longitudinal oscillation is observed in the other filament after the passing of the shock wave. The velocity amplitude and period are about 26.8 km s{sup –1} and 80.3 minutes, respectively. We propose that the orientation of a filament or prominence relative to the normal vector of the incoming shock should be an important factor for launching transverse or longitudinal filament oscillations. In addition, the restoring forces of the transverse prominence are most likely due to the coupling of gravity and magnetic tension of the supporting magnetic field, while that for the longitudinal filament oscillation is probably the resultant force of gravity and magnetic pressure.« less

The stability of weight status through the early to middle childhood years in Australia: a longitudinal study.

PubMed

Wheaton, Nikita; Millar, Lynne; Allender, Steven; Nichols, Melanie

2015-04-28

To investigate the sociodemographic and behavioural factors associated with incidence, persistence or remission of obesity in a longitudinal sample of Australian children aged 4-10 years. Nationally representative Longitudinal Study of Australian Children (LSAC). The sample for this analysis included all children in the Kinder cohort (aged 4-5 years at wave 1) who participated in all four waves of LSAC (wave 1, 2004, aged 4-5 years; wave 2, 2006, aged 6-7 years; wave 3, 2008, aged 8-9 years and wave 4, 2010, aged 10-11 years). Of the 4983 children who participated in the baseline (wave 1) survey, 4169 (83.7%) children completed all four waves of data collection. Movement of children between weight status categories over time and individual-level predictors of weight status change (sociodemographic characteristics, selected dietary and activity behaviours). The study found tracking of weight status across this period of childhood. There was an inverse association observed between socioeconomic position and persistence of overweight/obesity. Sugar-sweetened beverages and fruit and vegetable intake and screen time appeared to be important predictors of stronger tracking. Overweight and obesity established early in childhood tracks strongly to the middle childhood years in Australia, particularly among children of lower socioeconomic position and children participating in some unhealthy behaviour patterns. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

A population-based longitudinal study of risk factors for suicide attempts in major depressive disorder.

PubMed

Bolton, James M; Pagura, Jina; Enns, Murray W; Grant, Bridget; Sareen, Jitender

2010-10-01

No longitudinal study has examined risk factors for future suicide attempts in major depressive disorder in a nationally representative sample. The objective of this study was to investigate baseline sociodemographic characteristics, comorbid mental disorders, specific depressive symptoms, and previous suicidal behavior as potential risk factors for suicide attempts at 3 years follow-up. Data came from the national epidemiologic survey on alcohol and related conditions (NESARC), a large nationally representative longitudinal survey of mental illness in adults [Wave 1 (2001-2002); Wave 2 (2004-2005) n=34,653]. Logistic regression examined associations between risk factors present at Wave 1 and suicide attempts at Wave 2 (n=169) among individuals with major depressive disorder at baseline assessment (n=6004). Risk factors for incident suicide attempts at Wave 2 (n=63) were identified among those with major depressive disorder at Wave 1 and no lifetime history of suicide attempts (n=5170). Results revealed specific comorbid anxiety, personality, and substance use disorders to be associated with incident suicide attempts at Wave 2. Comorbid borderline personality disorder was strongly associated with suicide attempts in all models. Several comorbid disorders were strongly associated with suicide attempts at Wave 2 even after adjusting for previous suicidal behavior, notably posttraumatic stress disorder (adjusted odds ratio (AOR)=2.20; 95% confidence interval (95% CI) 1.27-3.83) and dependent personality disorder (AOR=4.43; 95% CI 1.93-10.18). These findings suggest that mental illness comorbidity confers an increased risk of future suicide attempts in major depressive disorder that is not solely accounted for by past suicidal behavior.

Do cyanobacteria swim using traveling surface waves?

PubMed Central

Ehlers, K M; Samuel, A D; Berg, H C; Montgomery, R

1996-01-01

Bacteria that swim without the benefit of flagella might do so by generating longitudinal or transverse surface waves. For example, swimming speeds of order 25 microns/s are expected for a spherical cell propagating longitudinal waves of 0.2 micron length, 0.02 micron amplitude, and 160 microns/s speed. This problem was solved earlier by mathematicians who were interested in the locomotion of ciliates and who considered the undulations of the envelope swept out by ciliary tips. A new solution is given for spheres propagating sinusoidal waveforms rather than Legendre polynomials. The earlier work is reviewed and possible experimental tests are suggested. Images Fig. 1 PMID:8710872

High-power, single-longitudinal-mode terahertz-wave generation pumped by a microchip Nd:YAG laser [Invited].

PubMed

Hayashi, Shin'ichiro; Nawata, Koji; Sakai, Hiroshi; Taira, Takunori; Minamide, Hiroaki; Kawase, Kodo

2012-01-30

We report on the development of a high-peak-power, single-longitudinal-mode and tunable injection-seeded terahertz-wave parametric generator using MgO:LiNbO3, which operates at room temperature. The high peak power (> 120 W) is enough to allow easy detection by commercial and calibrated pyroelectric detectors, and the spectral resolution (< 10 GHz) is the Fourier transform limit of the sub-nanosecond terahertz-wave pulse. The tunability (1.2-2.8 THz) and the small footprint size (A3 paper, 29.7 × 42 cm) are suitable for a variety of applications.

The focusing effect of P-wave in the Moon's and Earth's low-velocity core. Analytical solution

NASA Astrophysics Data System (ADS)

Fatyanov, A. G.; Burmin, V. Yu

2018-04-01

The important aspect in the study of the structure of the interiors of planets is the question of the presence and state of core inside them. While for the Earth this task was solved long ago, the question of whether the core of the Moon is in a liquid or solid state up to the present is debatable up to present. If the core of the Moon is liquid, then the velocity of longitudinal waves in it should be lower than in the surrounding mantle. If the core is solid, then most likely, the velocity of longitudinal waves in it is higher than in the mantle. Numerical calculations of the wave field allow us to identify the criteria for drawing conclusions about the state of the lunar core. In this paper we consider the problem of constructing an analytical solution for wave fields in a layered sphere of arbitrary radius. A stable analytic solution is obtained for the wave fields of longitudinal waves in a three-layer sphere. Calculations of the total wave fields and rays for simplified models of the Earth and the Moon with real parameters are presented. The analytical solution and the ray pattern showed that the low-velocity cores of the Earth and the Moon possess the properties of a collecting lens. This leads to the emergence of a wave field focusing area. As a result, focused waves of considerable amplitude appear on the surface of the Earth and the Moon. In the Earth case, they appear before the first PKP-wave arrival. These are so-called "precursors", which continue in the subsequent arrivals of waves. At the same time, for the simplified model of the Earth, the maximum amplitude growth is observed in the 147-degree region. For the Moon model, the maximum amplitude growth is around 180°.

Shortened Sleep Duration does not Predict Obesity in Adolescents

PubMed Central

Calamaro, Christina J.; Park, Sunhee; Mason, Thornton B. A.; Marcus, Carole L.; Weaver, Terri E.; Pack, Allan; Ratcliffe, Sarah J.

2010-01-01

Obesity continues to be a major public health issue. In adolescents, there are limited studies on the relationship between obesity and sleep duration. We hypothesied that average sleep duration of less than 6 hours in adolescents was associated with obesity. Data was from the National Longitudinal Study of Adolescent Health (ADD Health); survey of 90,000 youths, ages 12 – 18 years; surveyed in several waves. The sample population for our study was 13,568. Weighted multiple logistic regression was used to identify relationship between obesity at Wave II and sleep duration, having adjusted for skipping breakfast ≥ 2/week; race, gender, parental income, TV ≥ 2hrs/day, depression, and obesity at Wave I. At Wave I, mean age 15.96±0.11 yrs; mean sleep hours 7.91±0.04. 10.6% and 11.2% of adolescents were obese at Waves I and II, respectively. Adjusted analyses suggest that effect of shortened sleep duration in Wave I was not significantly predictive of obesity in Wave II (p<0.218).Longitudinally, depression and TV ≥ 2hrs/day at Wave I was associated with higher risk of obesity at Wave II in adjusted analyses. Depressed adolescents were almost twice as likely to be obese (OR=1.84, 95% CI=1.25–2.72); adolescents who watched TV ≥ 2hrs/day were 37% more likely to be obese (OR=1.37, 95% CI=1.09–1.72).Environmental factors including TV ≥ 2hrs/day and depression were significantly associated with obesity; shortened sleep duration was not. Future longitudinal studies in adolescents are needed to determine whether timing of television watching directly influences sleep patterns, and ultimately obesity. PMID:20545836

The heritability of insomnia progression during childhood/adolescence: results from a longitudinal twin study.

PubMed

Barclay, Nicola L; Gehrman, Philip R; Gregory, Alice M; Eaves, Lindon J; Silberg, Judy L

2015-01-01

To determine prevalence and heritability of insomnia during middle/late childhood and adolescence; examine longitudinal associations in insomnia over time; and assess the extent to which genetic and environmental factors on insomnia remain stable, or whether new factors come into play, across this developmental period. Longitudinal twin study. Academic medical center. There were 739 complete monozygotic twin pairs (52%) and 672 complete dizygotic twin pairs (48%) initially enrolled and were followed up at three additional time points (waves). Mode ages at each wave were 8, 10, 14, and 15 y (ages ranged from 8-18 y). None. Clinical ratings of insomnia symptoms were assessed using the Child and Adolescent Psychiatric Assessment (CAPA) by trained clinicians, and rated according to Diagnostic and Statistical Manual of Mental Disorders (DSM)-III-R criteria for presence of 'clinically significant insomnia', over four sequential waves. Insomnia symptoms were prevalent but significantly decreased across the four waves (ranging from 16.6% to 31.2%). 'Clinically significant insomnia' was moderately heritable at all waves (h² range = 14% to 38%), and the remaining source of variance was the nonshared environment. Multivariate models indicated that genetic influences at wave 1 contributed to insomnia at all subsequent waves, and that new genetic influences came into play at wave 2, which further contributed to stability of symptoms. Nonshared environmental influences were time-specific. Insomnia is prevalent in childhood and adolescence, and is moderately heritable. The progression of insomnia across this developmental time period is influenced by stable as well as new genetic factors that come into play at wave 2 (modal age 10 y). Molecular genetic studies should now identify genes related to insomnia progression during childhood and adolescence. © 2014 Associated Professional Sleep Societies, LLC.

Problems of interaction longitudinal shear waves with V-shape tunnels defect

NASA Astrophysics Data System (ADS)

Popov, V. G.

2018-04-01

The problem of determining the two-dimensional dynamic stress state near a tunnel defect of V-shaped cross-section is solved. The defect is located in an infinite elastic medium, where harmonic longitudinal shear waves are propagating. The initial problem is reduced to a system of two singular integral or integro-differential equations with fixed singularities. A numerical method for solving these systems with regard to the true asymptotics of the unknown functions is developed.

Public School Teacher Attrition and Mobility in the First Five Years: Results from the First through Fifth Waves of the 2007-08 Beginning Teacher Longitudinal Study. First Look. NCES 2015-337

ERIC Educational Resources Information Center

Gray, Lucinda; Taie, Soheyla

2015-01-01

This First Look report provides selected findings from all five waves of the Beginning Teacher Longitudinal Study (BTLS) along with data tables and methodological information. The BTLS follows a sample of public elementary and secondary school teachers who participated in the 2007-08 Schools and Staffing Survey (SASS), and whose first year of…

Study on the electromechanical coupling coefficient of Rayleigh-type surface acoustic waves in semi-infinite piezoelectrics/non-piezoelectrics superlattices.

PubMed

Chen, Shi; Zhang, Yinhong; Lin, Shuyu; Fu, Zhiqiang

2014-02-01

The electromechanical coupling coefficient of Rayleigh-type surface acoustic waves in semi-infinite piezoelectrics/non-piezoelectrics superlattices is investigated by the transfer matrix method. Research results show the high electromechanical coupling coefficient can be obtained in these systems. The optimization design of it is also discussed fully. It is significantly influenced by electrical boundary conditions on interfaces, thickness ratios of piezoelectric and non-piezoelectric layers, and material parameters (such as velocities of pure longitudinal and transversal bulk waves in non-piezoelectric layers). In order to obtain higher electromechanical coupling coefficient, shorted interfaces, non-piezoelectric materials with large velocities of longitudinal and transversal bulk waves, and proper thickness ratios should be chosen. Copyright © 2013 Elsevier B.V. All rights reserved.

Two-tone nonlinear electrostatic waves in the quantum electron–hole plasma of semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dubinov, A. E., E-mail: dubinov-ae@yandex.ru; Kitayev, I. N.

2017-01-15

Longitudinal electrostatic waves in the quantum electron–hole plasma of semiconductors are considered taking into account the degeneracy of electrons and holes and the exchange interaction. It is found in the framework of linear theory that the dispersion curve of longitudinal waves has two branches: plasmon and acoustic. An expression for the critical cutoff frequency for plasma oscillations and an expression for the speed of sound for acoustic vibrations are derived. It is shown that the plasma wave always exists in the form of a superposition of two components, characterized by different periods and wavelengths. Two nonlinear solutions are obtained withinmore » nonlinear theory: one in the form of a simple superposition of two tones and the other in the form of beats.« less

Stress evaluation of metallic material under steady state based on nonlinear critically refracted longitudinal wave

NASA Astrophysics Data System (ADS)

Mao, Hanling; Zhang, Yuhua; Mao, Hanying; Li, Xinxin; Huang, Zhenfeng

2018-06-01

This paper presents the study of applying the nonlinear ultrasonic wave to evaluate the stress state of metallic materials under steady state. The pre-stress loading method is applied to guarantee components with steady stress. Three kinds of nonlinear ultrasonic experiments based on critically refracted longitudinal wave are conducted on components which the critically refracted longitudinal wave propagates along x, x1 and x2 direction. Experimental results indicate the second and third order relative nonlinear coefficients monotonically increase with stress, and the normalized relationship is consistent with simplified dislocation models, which indicates the experimental result is logical. The combined ultrasonic nonlinear parameter is proposed, and three stress evaluation models at x direction are established based on three ultrasonic nonlinear parameters, which the estimation error is below 5%. Then two stress detection models at x1 and x2 direction are built based on combined ultrasonic nonlinear parameter, the stress synthesis method is applied to calculate the magnitude and direction of principal stress. The results show the prediction error is within 5% and the angle deviation is within 1.5°. Therefore the nonlinear ultrasonic technique based on LCR wave could be applied to nondestructively evaluate the stress of metallic materials under steady state which the magnitude and direction are included.

Longitudinal Direct and Indirect Pathways Linking Older Sibling Competence to the Development of Younger Sibling Competence.

ERIC Educational Resources Information Center

Brody, Gene H.; Kim, Sooyeon; Murry, Velma McBride; Brown, Anita C.

2003-01-01

Tested links between early adolescent older sibling (OS) and younger sibling (YS) competence in rural African American families. Found that OS competence was stable across time and related to improvements in mothers' psychological functioning from Wave 1 to Wave 2. Mothers' Wave-2 psychological functioning related to Wave-3 involved-supportive…

Generation of auroral kilometric radiation by a finite-size source in a dipole magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burinskaya, T. M., E-mail: tburinsk@iki.rssi.ru; Shevelev, M. M.

2016-10-15

Generation, amplification, and propagation of auroral kilometric radiation in a narrow three-dimensional plasma cavity in which a weakly relativistic electron beam propagates is studied in the geometrical optics approximation. It is shown that the waves that start with a group velocity directed earthward and have optimal relation between the wave vector components determining the linear growth rate and the wave residence time inside the amplification region undergo the largest amplification. Taking into account the longitudinal velocity of fast electrons results in the shift of the instability domain toward wave vectors directed to the Earth and leads to a change inmore » the dispersion relation, due to which favorable conditions are created for the generation of waves with frequencies above the cutoff frequency for the cold background plasma at the wave generation altitude. The amplification factor for these waves is lower than for waves that have the same wave vectors but are excited by the electron beams with lower velocities along the magnetic field. For waves excited at frequencies below the cutoff frequency of the background plasma at the generation altitude, the amplification factor increases with increasing longitudinal electron velocity, because these waves reside for a longer time in the amplification region.« less

Simple Harmonic Motion in Harmonic Plane Waves.

ERIC Educational Resources Information Center

Benumof, Reuben

1980-01-01

Discusses the distribution of kinetic and potential energy in transverse and longitudinal waves and examines the transmission of power and momentum. This discussion is intended to aid in understanding the simple harmonic motion of a particle involved in the propagation of a harmonic mechanical plane wave. (HM)

Longitudinal determinants of depression among World Trade Center Health Registry enrollees, 14-15 years after the 9/11 attacks.

PubMed

Jacobson, Melanie H; Norman, Christina; Nguyen, Angela; Brackbill, Robert M

2018-03-15

Exposure to the September 11, 2001 (9/11) terrorist attacks has been found to be associated with posttraumatic stress disorder (PTSD) and comorbid PTSD and depression up to 10-11 years post-disaster. However, little is known about the longitudinal predictors of mental health conditions over time. We examined longitudinal determinants of depression within strata of PTSD among 21,258 enrollees of the World Trade Center Health Registry who completed four questionnaires over 14 years of follow-up (Wave 1 in 2003-04; Wave 2 in 2005-06; Wave 3 in 2011-12; and Wave 4 in 2015-16). PTSD status was measured using the PTSD checklist on all four waves and defined as a score of ≥ 44; depression was assessed using the 8-item Patient Health Questionnaire at Waves 3 and 4 and defined as a score of ≥ 10. Across Waves 3 and 4, 18.6% experienced depression, and it was more common among those who ever had PTSD (56.1%) compared with those who had not (5.6%). Across PTSD strata, predictors of depression included low income, unemployment, low social integration and support, post-9/11 traumatic life events, and chronic physical illness. These factors also decreased the likelihood of recovering from depression. Depression symptoms were not measured at Waves 1 and 2; data was self-reported. These findings highlight the substantial burden of depression in a trauma-exposed population 14-15 years post-disaster, especially among those with PTSD. Similar life stressors predicted the course of depression among those with and without PTSD which may inform public health and clinical interventions. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Effect of Wave Reflection and Arterial Stiffness on the Risk of Development of Hypertension in Japanese Men.

PubMed

Tomiyama, Hirofumi; Komatsu, Shunsuke; Shiina, Kazuki; Matsumoto, Chisa; Kimura, Kazutaka; Fujii, Masatsune; Takahashi, Lisa; Chikamori, Taishiro; Yamashina, Akira

2018-05-08

We conducted analyses of repeated-measures data to examine whether pressure wave reflection acts additively or synergistically with arterial stiffness in the pathogenesis of hypertension. In 3172 middle-aged (42±9 years) healthy Japanese men without hypertension at the study baseline, systolic and diastolic blood pressures, brachial-ankle pulse wave velocity, and radial augmentation index were measured annually during a 9-year study period. Of these, 474 participants (15%) developed hypertension by the end of the study period. Binary logistic regression analysis demonstrated significant individual odds ratios for both baseline brachial-ankle pulse wave velocity and radial augmentation index for the development of hypertension. The rate of onset of hypertension during the study period was highest in the participant group with high values for both brachial-ankle pulse wave velocity and radial augmentation index at study baseline (262 of 965 participants: 27%). The generalized estimating equation analysis revealed that both radial augmentation index (estimate=0.06, SE=0.03, P =0.05) and brachial-ankle pulse wave velocity (estimate=0.07×10 -1 , SE=0.02×10 -1 , P <0.01) showed significant longitudinal association with new onset of hypertension, with no significant interaction. In Japanese men, abnormal wave reflection and increased arterial stiffness may be additively associated with the risk of new onset of hypertension. Abnormal wave reflection and elevated central blood pressure may be longitudinally associated with increase in arterial stiffness, and this longitudinal association may be a mechanism underlying the additive effect of these 2 variables on the risk of new onset of hypertension. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Longitudinal Trajectories of Perceived Body Weight: Adolescence to Early Adulthood

ERIC Educational Resources Information Center

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…

Longitudinal Relations between Ethnic/Racial Identity Process and Content: Exploration, Commitment, and Salience among Diverse Adolescents

ERIC Educational Resources Information Center

Wang, Yijie; Douglass, Sara; Yip, Tiffany

2017-01-01

The present study bridges the process and content perspectives of ethnic/racial identity (ERI) by examining the longitudinal links between identity process (i.e., exploration, commitment) and a component of identity content, salience. Data were drawn from a 4-wave longitudinal study of 405 ethnically/racially diverse adolescents (63% female) from…

Mathematical theory of cylindrical isothermal blast waves in a magnetic field. [with application to supernova remnant evolution

NASA Technical Reports Server (NTRS)

Lerche, I.

1981-01-01

An analysis is conducted regarding the properties of cylindrically symmetric self-similar blast waves propagating away from a line source into a medium whose density and magnetic field (with components in both the phi and z directions) both vary as r to the -(omega) power (with omega less than 1) ahead of the blast wave. The main results of the analysis can be divided into two classes, related to a zero azimuthal field and a zero longitudinal field. In the case of the zero longitudinal field it is found that there are no physically acceptable solutions with continuous postshock variations of flow speed and gas density.

Rayleigh-Brillouin scattering studies of the rotation-translation coupling and bulk viscosity relaxation of liquids composed of anisotropic molecules: p-Anisaldehyde and aniline

NASA Astrophysics Data System (ADS)

O'Steen, B. L.; Wang, C. H.; Fytas, G.

1984-04-01

The coupling of reorientational motion to longitudinal acoustic modes was investigated by studying the Rayleigh-Brillouin spectra of aniline and p-anisaldehyde over a wide range of scattering angles. Aniline and p-anisaldehyde were chosen for investigation since their depolarized spectra at the temperature of interest show a pronounced coupling between orientation and shear modes. The experimental results for attenuation and velocity of the longitudinal waves show that there is indeed relaxation in the shear viscosity. However, shear relaxation due to the coupling of the longitudinal acoustic mode to reorientation plays only a minor role in causing the dispersion of the hypersonic longitudinal waves. To account for the large dispersion, it is essential to consider the mechanism associated with the relaxation of the bulk viscosity through the T-V energy transfer.

Diameter effect on stress-wave evaluation of modulus of elasticity of logs

Treesearch

Xiping Wang; Robert J. Ross; Brian K. Brashaw; John Punches; John R. Erickson; John W. Forsman; Roy E. Pellerin

2004-01-01

Recent studies on nondestructive evaluation (NDE) of logs have shown that a longitudinal stress-wave method can be used to nondestructively evaluate the modulus of elasticity (MOE) of logs. A strong relationship has been found between stress-wave MOE and static MOE of logs, but a significant deviation was observed between stress-wave and static values. The objective of...

Diameter effect on stress-wave evaluation of modulus of elasticity of logs

Treesearch

Xiping Wang; Robert J. Ross; Brian K. Brashaw; John R. Erickson; John W. Forsman; Roy Pellerin

2003-01-01

Recent studies on nondestructive evaluation (NDE) of logs have shown that a longitudinal stress-wave method can be used to nondestructively evaluate the modulus of elasticity (MOE) of logs. A strong relationship has been found between stress-wave MOE and static MOE of logs, but a significant deviation was observed between stress-wave and static values. The objective of...

Prevention of adolescent problem behavior: longitudinal impact of the Project P.A.T.H.S. in Hong Kong.

PubMed

Shek, Daniel T L; Yu, Lu

2011-03-07

The present study attempts to examine the longitudinal impact of a curriculum-based positive youth development program, entitled the Project P.A.T.H.S. (Positive Adolescent Training through Holistic Social Programmes), on adolescent problem behavior in Hong Kong. Using a longitudinal randomized group design, six waves of data were collected from 19 experimental schools (n = 3,797 at Wave 1) in which students participated in the Project P.A.T.H.S. and 24 control schools (n = 4,049 at Wave 1). At each wave, students responded to questions asking about their current problem behaviors, including delinquency and use of different types of drugs, and their intentions of engaging in such behaviors in the future. Results based on individual growth curve modeling generally showed that the participants displayed lower levels of substance abuse and delinquent behavior than did the control students. Participants who regarded the program to be helpful also showed lower levels of problem behavior than did the control students. The present findings suggest that the Project P.A.T.H.S. is effective in preventing adolescent problem behavior in the junior secondary school years.

Emotionally numb: Desensitization to community violence exposure among urban youth.

PubMed

Kennedy, Traci M; Ceballo, Rosario

2016-05-01

Community violence exposure (CVE) is associated with numerous psychosocial outcomes among youth. Although linear, cumulative effects models have typically been used to describe these relations, emerging evidence suggests the presence of curvilinear associations that may represent a pattern of emotional desensitization among youth exposed to chronic community violence. This study uses longitudinal data to investigate relations between CVE and both internalizing and externalizing symptoms among 3,480 youth ages 3 to 12 at baseline and 9 to 18 at outcome. Results support desensitization models, as evidenced by longitudinal quadratic associations between Wave 2 CVE and Wave 3 anxiety/depressive symptoms, alongside cross-sectional linear associations between Wave 3 CVE and Wave 3 aggression. Neither age nor gender moderated the associations between CVE and well-being. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Poorer Visual Acuity Is Associated with Declines in Cognitive Performance Across Multiple Cognitive Domains: The Maine-Syracuse Longitudinal Study.

PubMed

Dearborn, Peter J; Elias, Merrill F; Sullivan, Kevin J; Sullivan, Cara E; Robbins, Michael A

2018-06-21

Prior studies have found associations between visual acuity (VA) and cognitive function. However, these studies used a limited range of cognitive measures and did not control for cardiovascular disease risk factors (CVD-RFs) and baseline function. The primary objective of this study was to analyze the associations of VA and cognitive performance using a thorough neuropsychological test battery. This study used community-dwelling sample data across the sixth (2001-2006) and seventh (2006-2010) waves of the Maine-Syracuse Longitudinal Study (n=655). Wave 6 VA as measured by the Snellen Eye Test was the primary predictor of wave 6 and wave 7 Global cognitive performance, Visual-Spatial Organization and Memory, Verbal Episodic Memory, Working Memory, Scanning and Tracking, and Executive Function. Additionally, VA was used to predict longitudinal changes in wave 7 cognitive performance (wave 6 performance adjusted). We analyzed these relationships with multiple linear and logistic regression models adjusted for age, sex, education, ethnicity, depressive symptoms, physical function deficits in addition to CVD-RFs, chronic kidney disease, homocysteine, continuous systolic blood pressure, and hypertension status. Adjusted for demographic covariates and CVD-RFs, poorer VA was associated with concurrent and approximate 5-year declines in Global cognitive function, Visual-Spatial Organization and Memory, and Verbal Episodic Memory. VA may be used in combination with other screening measures to determine risk for cognitive decline. (JINS, 2018, 24, 1-9).

Longitudinal Associations among Discordant Sexual Orientation Dimensions and Hazardous Drinking in a Cohort of Sexual Minority Women

PubMed Central

Talley, Amelia E.; Aranda, Frances; Hughes, Tonda L.; Everett, Bethany; Johnson, Timothy P.

2015-01-01

We examined differences between sexual minority women’s (SMW’s) sexual identity and sexual behavior or sexual attraction as potential contributors to hazardous drinking across a 10-year period. Data are from a longitudinal study examining drinking and drinking-related problems in a diverse, community-based sample of self-identified SMW (Wave 1: n = 447; Wave 2: n = 384; Wave 3: n = 354). Longitudinal cross-lagged models showed that SMW who report higher levels of identity-behavior or identity-attraction discordance may be at greater risk of concurrent and subsequent hazardous drinking. Results of multigroup models suggest that sexual orientation discordance is a more potent risk factor for risky drinking outcomes among SMW in older adulthood than in younger adulthood. Findings support that discordance between sexual orientation dimensions may contribute to hazardous drinking among SMW and provide evidence that cognitive-behavioral consistency is important for individuals expressing diverse and fluid sexual identities, attraction, and behavior. PMID:25911224

Study on Dissipation of Landslide Generated Waves in Different Shape of Reservoirs

NASA Astrophysics Data System (ADS)

An, Y.; Liu, Q.

2017-12-01

The landslide generated waves are major risks for many reservoirs located in mountainous areas. As the initial wave is often very huge (e.g. 30m of the height in Xiaowan event, 2009, China), the dissipation of the wave, which is closely connected with the shape of the reservoir (e.g. channel type vs. lake type), is a crucial factor in risk estimation and prevention. While even for channel type reservoir, the wave damping also varies a lot due to details of the shape such as branches and turnings. Focusing on the influence of this shape details on the wave damping in channel type reservoir, we numerically studied two landslide generated wave events with both a triangle shape of the cross section but different longitudinal shape configurations (Xiaowan event in 2009 and an assuming event in real topography). The two-dimensional Saint-Venant equation and dry-wet boundary treatment method are used to simulate the wave generation and propagation processes. The simulation is based on an open source code called `Basilisk' and the adaptive mesh refinement technique is used to achieve enough precision with affordable computational resources. The sensitivity of the parameters representing bed drag and the vortex viscosity is discussed. We found that the damping is relatively not sensitive to the bed drag coefficient, which is natural as the water depth is large compared with wave height. While the vortex viscosity needs to be chosen carefully as it is related to cross sectional velocity distribution. It is also found that the longitudinal shape, i.e. the number of turning points and branches, is the key factor influencing the wave damping. The wave height at the far field could be only one seventh comparing with the initial wave in the case with complex longitudinal shape, while the damping is much weaker in the straight channel case. We guess that this phenomenon is due to the increasing sloshing at these abruptly changed positions. This work could provide a deeper understanding on the landslide generated waves in the reservoir and helps engineers design better risk prevention facilities.

The effect of compressive viscosity and thermal conduction on the longitudinal MHD waves

NASA Astrophysics Data System (ADS)

Bahari, K.; Shahhosaini, N.

2018-05-01

longitudinal Magnetohydrodynamic (MHD) oscillations have been studied in a slowly cooling coronal loop, in the presence of thermal conduction and compressive viscosity, in the linear MHD approximation. WKB method has been used to solve the governing equations. In the leading order approximation the dispersion relation has been obtained, and using the first order approximation the time dependent amplitude has been determined. Cooling causes the oscillations to amplify and damping mechanisms are more efficient in hot loops. In cool loops the oscillation amplitude increases with time but in hot loops the oscillation amplitude decreases with time. Our conclusion is that in hot loops the efficiency of the compressive viscosity in damping longitudinal waves is comparable to that of the thermal conduction.

The effect of compressive viscosity and thermal conduction on the longitudinal MHD waves

NASA Astrophysics Data System (ADS)

Bahari, K.; Shahhosaini, N.

2018-07-01

Longitudinal magnetohydrodynamic (MHD) oscillations have been studied in a slowly cooling coronal loop, in the presence of thermal conduction and compressive viscosity, in the linear MHD approximation. The WKB method has been used to solve the governing equations. In the leading order approximation the dispersion relation has been obtained, and using the first-order approximation the time-dependent amplitude has been determined. Cooling causes the oscillations to amplify and damping mechanisms are more efficient in hot loops. In cool loops the oscillation amplitude increases with time but in hot loops the oscillation amplitude decreases with time. Our conclusion is that in hot loops the efficiency of the compressive viscosity in damping longitudinal waves is comparable to that of the thermal conduction.

Standard deviation of vertical two-point longitudinal velocity differences in the atmospheric boundary layer.

NASA Technical Reports Server (NTRS)

Fichtl, G. H.

1971-01-01

Statistical estimates of wind shear in the planetary boundary layer are important in the design of V/STOL aircraft, and for the design of the Space Shuttle. The data analyzed in this study consist of eleven sets of longitudinal turbulent velocity fluctuation time histories digitized at 0.2 sec intervals with approximately 18,000 data points per time history. The longitudinal velocity fluctuations were calculated with horizontal wind and direction data collected at the 18-, 30-, 60-, 90-, 120-, and 150-m levels. The data obtained confirm the result that Eulerian time spectra transformed to wave-number spectra with Taylor's frozen eddy hypothesis possess inertial-like behavior at wave-numbers well out of the inertial subrange.

Ultrasonic wave velocity measurement in small polymeric and cortical bone specimens

NASA Technical Reports Server (NTRS)

Kohles, S. S.; Bowers, J. R.; Vailas, A. C.; Vanderby, R. Jr

1997-01-01

A system was refined for the determination of the bulk ultrasonic wave propagation velocity in small cortical bone specimens. Longitudinal and shear wave propagations were measured using ceramic, piezoelectric 20 and 5 MHz transducers, respectively. Results of the pulse transmission technique were refined via the measurement of the system delay time. The precision and accuracy of the system were quantified using small specimens of polyoxymethylene, polystyrene-butadiene, and high-density polyethylene. These polymeric materials had known acoustic properties, similarity of propagation velocities to cortical bone, and minimal sample inhomogeneity. Dependence of longitudinal and transverse specimen dimensions upon propagation times was quantified. To confirm the consistency of longitudinal wave propagation in small cortical bone specimens (< 1.0 mm), cut-down specimens were prepared from a normal rat femur. Finally, cortical samples were prepared from each of ten normal rat femora, and Young's moduli (Eii), shear moduli (Gij), and Poisson ratios (Vij) were measured. For all specimens (bone, polyoxymethylene, polystyrene-butadiene, and high-density polyethylene), strong linear correlations (R2 > 0.997) were maintained between propagation time and distance throughout the size ranges down to less than 0.4 mm. Results for polyoxymethylene, polystyrene-butadiene, and high-density polyethylene were accurate to within 5 percent of reported literature values. Measurement repeatability (precision) improved with an increase in the wave transmission distance (propagating dimension). No statistically significant effect due to the transverse dimension was detected.

Stationary Planetary Waves in the Mars Winter Atmosphere as seen by the Radio Science Experiment MaRS on Mars Express

NASA Astrophysics Data System (ADS)

Tellmann, Silvia; Pätzold, Martin; Häusler, Bernd; Tyler, Leonard G.; Hinson, David P.

2015-11-01

Stationary (Rossby) Waves are excited by the interaction of the zonally varying topography with the strong eastward winter jets. They lead to distinctive longitudinal temperature variations which contribute significantly to the asymmetry of the seasonal polar CO2 ice caps and are also important for the dust redistribution in the planetary atmosphere.Radio Science profiles from the Mars Express Radio Science Experiment MaRS at northern and southern high latitudes are used to gain insight into winter stationary wave structures on both hemispheres.Mars Global Surveyor (MGS) radio occultation measurements from the same season and year with their exceptionally good longitudinal and temporal coverage can be used to estimate the influence of transient eddies. Transient waves are especially important in the northern winter hemisphere.Wave number 2 stationary waves, driven by topography, are dominant in the northern winter latitudes while the wave number 1 wave is the most significant wave number during southern winter. The wave amplitudes peak around winter solstice on both hemispheres.Radio occultation measurements provide the unique opportunity to determine simultaneous measurements of temperature and geopotential height structures. Assuming geostrophic balance, these measurements can be used to determine meridional winds and eddy heat fluxes which provide further insight into the contribution of stationary waves to the heat exchange between the poles and the lower latitudes.

Higher Weight, Lower Education: A Longitudinal Association between Adolescents' Body Mass Index and Their Subsequent Educational Achievement Level?

ERIC Educational Resources Information Center

Larsen, Junilla K.; Kleinjan, Marloes; Engels, Rutger C. M. E.; Fisher, Jennifer O.; Hermans, Roel

2014-01-01

Background: The purpose of this study was to examine the association between adolescents' body mass index (BMI) z-scores and their subsequent level of schooling, extending previous longitudinal research by using objectively measured weight and height data. Methods: A longitudinal study with 3 study waves (1-year intervals) involving 1248 Dutch…

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

ERIC Educational Resources Information Center

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;…

Longitudinal Stability of the Beck Depression Inventory II: A Latent Trait-State-Occasion Model

ERIC Educational Resources Information Center

Wu, Pei-Chen

2016-01-01

In a six-wave longitudinal study with two cohorts (660 adolescents and 630 young adults), this study investigated the longitudinal stability of the Beck Depression Inventory II (BDI-II) using the Trait-State-Occasion (TSO) model. The results revealed that the full TSO model was the best fitting representation of the depression measured by the…

Strategies for Longitudinal Analysis of the Career Paths of Beginning Teachers: Results from the First through Fourth Waves of the 2007-08 Beginning Teacher Longitudinal Study. Research and Development Report. NCES 2013-336

ERIC Educational Resources Information Center

Gray, Lucinda; Brauen, Marsha

2013-01-01

To learn more about the early career patterns of beginning teachers, the National Center for Education Statistics (NCES) of the Institute of Education Sciences within the U.S. Department of Education undertook the Beginning Teacher Longitudinal Study (BTLS). The ultimate purpose of this report is to develop a strategy for the longitudinal analysis…

Three-dimensional continuous particle focusing in a microfluidic channel via standing surface acoustic waves (SSAW).

PubMed

Shi, Jinjie; Yazdi, Shahrzad; Lin, Sz-Chin Steven; Ding, Xiaoyun; Chiang, I-Kao; Sharp, Kendra; Huang, Tony Jun

2011-07-21

Three-dimensional (3D) continuous microparticle focusing has been achieved in a single-layer polydimethylsiloxane (PDMS) microfluidic channel using a standing surface acoustic wave (SSAW). The SSAW was generated by the interference of two identical surface acoustic waves (SAWs) created by two parallel interdigital transducers (IDTs) on a piezoelectric substrate with a microchannel precisely bonded between them. To understand the working principle of the SSAW-based 3D focusing and investigate the position of the focal point, we computed longitudinal waves, generated by the SAWs and radiated into the fluid media from opposite sides of the microchannel, and the resultant pressure and velocity fields due to the interference and reflection of the longitudinal waves. Simulation results predict the existence of a focusing point which is in good agreement with our experimental observations. Compared with other 3D focusing techniques, this method is non-invasive, robust, energy-efficient, easy to implement, and applicable to nearly all types of microparticles.

Making Sound Connections

ERIC Educational Resources Information Center

Deal, Walter F., III

2007-01-01

Sound provides and offers amazing insights into the world. Sound waves may be defined as mechanical energy that moves through air or other medium as a longitudinal wave and consists of pressure fluctuations. Humans and animals alike use sound as a means of communication and a tool for survival. Mammals, such as bats, use ultrasonic sound waves to…

Second Order Accurate Finite Difference Methods

DTIC Science & Technology

1984-08-20

34Nonlinear Modulation of Torsional Waves in Elastic Rods," 3. Phys. Soc. Japan, V. 42, No. 6, pp. 2056-2064, 1977. 10. S. S. Antman and T. Liu. "Travelling...waves in a circular rod. The equations have been solved for coupling effects in torsional and longitudinal waves. Antman and Liu (10) have studied

Proofs for the Wave Theory of Plants

NASA Astrophysics Data System (ADS)

Wagner, Orvin E.

1997-03-01

Oscillatory behavior in plants. (2)Standing waves observed coming from probes equally spaced up tree trunks and freshly cut live wood samples. (3)Beat frequencies observed while applying AC voltages to plants. (4)Plant length quantization. (5)Plant growth angle and voltage quantization with respect to the gravitational field. (6)The measurement of plant frequences with a low frequency spectrum analyzer which correlate with the frequencies observed by other means such as by measuring plant lengths, considered as half wavelengths, and beat frequencies. (7)Voltages obtained from insulated, isolated from light, diode dies placed in slits in tree trunks. Diodes become relatively low impedance sources for voltages as high as eight volts. Diodes indicate charge separating longitudinal standing waves sweeping up and down a tree trunk. Longitudinal waves also indicated by plant structure. (8)The measured discrete wave velocities appear to be dependent on their direction of travel with respect to the gravitational field. These provide growth references for the plant and a wave guide affect. For references see Wagner Research Laboratory Web Page.

Impact of chronic illness timing and persistence at school entry on child and parent outcomes: Australian longitudinal study.

PubMed

Quach, Jon; Barnett, Tony

2015-01-01

To understand the prevalence and timing of child chronic illness at school entry; associations with child learning, behavior and health-related quality of life and parent mental health at ages 6 to 7, 8 to 9, and 10 to 11 years; and cumulative health care costs. Data were drawn from the first 4 waves of the Longitudinal Study of Australian Children. Children were aged 4 to 5 years at wave 1, with data collection every 2 years. Parent-reported timing of child chronic illness at school entry was categorized into 4 chronic illness groups based on changes between waves 1 and 2: none, resolving, incident and persistent. Child outcomes included: parent-reported quality of life, parent- and teacher-reported behavior, teacher-reported child learning, teacher-reported child-teacher relationship, directly assessed nonverbal and verbal cognition and parent self-reported mental health. Linear regression, adjusted for gender and socioeconomic position, was used to quantify longitudinal associations between chronic illness timing at school entry with outcomes at age 6 to 7 years, 8 to 9 years and 10 to 11 years. Of the 4983 children enrolled in the study, chronic illness data was available for 4464 children (89.6%) at both waves 1 and 2. From wave 1, 6.1% had a condition that persisted until wave 2, while 14.1% had a condition that resolved. Furthermore, 4.7% had a newly emerging condition at wave 2. Compared with the no chronic illness group, children with persistent or emerging chronic illness during school entry had the poorest outcomes (except father's mental health) at all time points, while children with resolving conditions had smaller differences. Child chronic illness at school entry is associated with poorer longitudinal child and maternal outcomes. Therefore, future research should aim to determine the risk and protective factors that contribute to the poorer child and parent outcomes experienced in this growing population. Copyright © 2015 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Interviewer effects on non-response propensity in longitudinal surveys: a multilevel modelling approach

PubMed Central

Vassallo, Rebecca; Durrant, Gabriele B; Smith, Peter W F; Goldstein, Harvey

2015-01-01

The paper investigates two different multilevel approaches, the multilevel cross-classified and the multiple-membership models, for the analysis of interviewer effects on wave non-response in longitudinal surveys. The models proposed incorporate both interviewer and area effects to account for the non-hierarchical structure, the influence of potentially more than one interviewer across waves and possible confounding of area and interviewer effects arising from the non-random allocation of interviewers across areas. The methods are compared by using a data set: the UK Family and Children Survey. PMID:25598587

Ultrasonically-assisted Thermal Stir Welding System

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor)

2014-01-01

A welding head assembly has a work piece disposed between its containment plates' opposing surfaces with the work piece being maintained in a plastic state thereof at least in a vicinity of the welding head assembly's stir rod as the rod is rotated about its longitudinal axis. The welding head assembly and the work piece experience relative movement there between in a direction perpendicular to the rod's longitudinal axis as the work piece is subjected to a compressive force applied by the containment plates. A first source coupled to the first containment plate applies a first ultrasonic wave thereto such that the first ultrasonic wave propagates parallel to the direction of relative movement. A second source coupled to the second containment plate applies a second ultrasonic wave thereto such that the second ultrasonic wave propagates parallel to the direction of relative movement.propagates parallel to the direction of relative movement.

Predicting cyberbullying perpetration in emerging adults: A theoretical test of the Barlett Gentile Cyberbullying Model.

PubMed

Barlett, Christopher; Chamberlin, Kristina; Witkower, Zachary

2017-04-01

The Barlett and Gentile Cyberbullying Model (BGCM) is a learning-based theory that posits the importance of positive cyberbullying attitudes predicting subsequent cyberbullying perpetration. Furthermore, the tenants of the BGCM state that cyberbullying attitude are likely to form when the online aggressor believes that the online environment allows individuals of all physical sizes to harm others and they are perceived as anonymous. Past work has tested parts of the BGCM; no study has used longitudinal methods to examine this model fully. The current study (N = 161) employed a three-wave longitudinal design to test the BGCM. Participants (age range: 18-24) completed measures of the belief that physical strength is irrelevant online and anonymity perceptions at Wave 1, cyberbullying attitudes at Wave 2, and cyberbullying perpetration at Wave 3. Results showed strong support for the BGCM: anonymity perceptions and the belief that physical attributes are irrelevant online at Wave 1 predicted Wave 2 cyberbullying attitudes, which predicted subsequent Wave 3 cyberbullying perpetration. These results support the BGCM and are the first to show empirical support for this model. Aggr. Behav. 43:147-154, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Acoustic excitations in nanosponges, low-k dielectric thin films and oxide glasses

NASA Astrophysics Data System (ADS)

Zhou, Wei

The invention of the laser has made optical spectroscopy techniques especially valuable research tools. Brillouin light scattering (BLS) is one such powerful technique to measure low energy excitations as acoustic phonons and magnons (spin waves) in materials. In this thesis, the BLS technique is utilized to investigate acoustic excitations and the underlying physics in different media: carbon nanosponges, ultra thin low-k dielectric films and soda germanate glasses. The highlights include: (1) acoustic response of carbon nanosponges solvated in the organic solvent dimethylformamide (DMF) and the discovery of nanosponge formation by exposure to laser radiation. The observed acoustic mode is confirmed as the slow longitudinal wave within the nanosponge suspension. The counter intuitive result of the sound speed decreasing with increasing weight fraction of carbon nano tubes is found and modeled by an effective medium approximation theory; (2) in ultra thin low-k dielectric films, longitudinal standing waves, transverse standing waves and surface waves are observed and recorded. Using a Green's function method, the elastic constants are calculated by fitting the dispersion of these waves. The displacements of standing waves are also simulated and found to behave like the modes in an organ pipe; (3) the long wavelength bulk longitudinal and transverse modes in soda germanate glasses (Na2O)x(GeO2) 1-x glasses are found to be anomalous with increasing soda concentration. The elastic constants C11 and C44 are determined and related quantities such as the elastic energy are also found to have maxima around a soda concentration of x=17%. The elastic properties are compared with those of (Na2O)x(SiO2)1-x glasses, and structural differences are discussed to account for the origin of their different behaviors.

Advanced analytical methodologies for measuring healthy ageing and its determinants, using factor analysis and machine learning techniques: the ATHLOS project

PubMed Central

Félix Caballero, Francisco; Soulis, George; Engchuan, Worrawat; Sánchez-Niubó, Albert; Arndt, Holger; Ayuso-Mateos, José Luis; Haro, Josep Maria; Chatterji, Somnath; Panagiotakos, Demosthenes B.

2017-01-01

A most challenging task for scientists that are involved in the study of ageing is the development of a measure to quantify health status across populations and over time. In the present study, a Bayesian multilevel Item Response Theory approach is used to create a health score that can be compared across different waves in a longitudinal study, using anchor items and items that vary across waves. The same approach can be applied to compare health scores across different longitudinal studies, using items that vary across studies. Data from the English Longitudinal Study of Ageing (ELSA) are employed. Mixed-effects multilevel regression and Machine Learning methods were used to identify relationships between socio-demographics and the health score created. The metric of health was created for 17,886 subjects (54.6% of women) participating in at least one of the first six ELSA waves and correlated well with already known conditions that affect health. Future efforts will implement this approach in a harmonised data set comprising several longitudinal studies of ageing. This will enable valid comparisons between clinical and community dwelling populations and help to generate norms that could be useful in day-to-day clinical practice. PMID:28281663

Constraining Alternative Theories of Gravity Using Pulsar Timing Arrays

NASA Astrophysics Data System (ADS)

Cornish, Neil J.; O'Beirne, Logan; Taylor, Stephen R.; Yunes, Nicolás

2018-05-01

The opening of the gravitational wave window by ground-based laser interferometers has made possible many new tests of gravity, including the first constraints on polarization. It is hoped that, within the next decade, pulsar timing will extend the window by making the first detections in the nanohertz frequency regime. Pulsar timing offers several advantages over ground-based interferometers for constraining the polarization of gravitational waves due to the many projections of the polarization pattern provided by the different lines of sight to the pulsars, and the enhanced response to longitudinal polarizations. Here, we show that existing results from pulsar timing arrays can be used to place stringent limits on the energy density of longitudinal stochastic gravitational waves. However, unambiguously distinguishing these modes from noise will be very difficult due to the large variances in the pulsar-pulsar correlation patterns. Existing upper limits on the power spectrum of pulsar timing residuals imply that the amplitude of vector longitudinal (VL) and scalar longitudinal (SL) modes at frequencies of 1/year are constrained, AVL<4 ×10-16 and ASL<4 ×10-17, while the bounds on the energy density for a scale invariant cosmological background are ΩVLh2<4 ×10-11 and ΩSLh2<3 ×10-13.

Constraining Alternative Theories of Gravity Using Pulsar Timing Arrays.

PubMed

Cornish, Neil J; O'Beirne, Logan; Taylor, Stephen R; Yunes, Nicolás

2018-05-04

The opening of the gravitational wave window by ground-based laser interferometers has made possible many new tests of gravity, including the first constraints on polarization. It is hoped that, within the next decade, pulsar timing will extend the window by making the first detections in the nanohertz frequency regime. Pulsar timing offers several advantages over ground-based interferometers for constraining the polarization of gravitational waves due to the many projections of the polarization pattern provided by the different lines of sight to the pulsars, and the enhanced response to longitudinal polarizations. Here, we show that existing results from pulsar timing arrays can be used to place stringent limits on the energy density of longitudinal stochastic gravitational waves. However, unambiguously distinguishing these modes from noise will be very difficult due to the large variances in the pulsar-pulsar correlation patterns. Existing upper limits on the power spectrum of pulsar timing residuals imply that the amplitude of vector longitudinal (VL) and scalar longitudinal (SL) modes at frequencies of 1/year are constrained, A_{VL}<4×10^{-16} and A_{SL}<4×10^{-17}, while the bounds on the energy density for a scale invariant cosmological background are Ω_{VL}h^{2}<4×10^{-11} and Ω_{SL}h^{2}<3×10^{-13}.

Advanced analytical methodologies for measuring healthy ageing and its determinants, using factor analysis and machine learning techniques: the ATHLOS project.

PubMed

Caballero, Francisco Félix; Soulis, George; Engchuan, Worrawat; Sánchez-Niubó, Albert; Arndt, Holger; Ayuso-Mateos, José Luis; Haro, Josep Maria; Chatterji, Somnath; Panagiotakos, Demosthenes B

2017-03-10

A most challenging task for scientists that are involved in the study of ageing is the development of a measure to quantify health status across populations and over time. In the present study, a Bayesian multilevel Item Response Theory approach is used to create a health score that can be compared across different waves in a longitudinal study, using anchor items and items that vary across waves. The same approach can be applied to compare health scores across different longitudinal studies, using items that vary across studies. Data from the English Longitudinal Study of Ageing (ELSA) are employed. Mixed-effects multilevel regression and Machine Learning methods were used to identify relationships between socio-demographics and the health score created. The metric of health was created for 17,886 subjects (54.6% of women) participating in at least one of the first six ELSA waves and correlated well with already known conditions that affect health. Future efforts will implement this approach in a harmonised data set comprising several longitudinal studies of ageing. This will enable valid comparisons between clinical and community dwelling populations and help to generate norms that could be useful in day-to-day clinical practice.

Nonlinear Longitudinal Mode Instability in Liquid Propellant Rocket Engine Preburners

NASA Technical Reports Server (NTRS)

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.

The Meaningful Identity: A Longitudinal Look at the Interplay between Identity and Meaning in Life in Adolescence

ERIC Educational Resources Information Center

Negru-Subtirica, Oana; Pop, Eleonora Ioana; Luyckx, Koen; Dezutter, Jessie; Steger, Michael F.

2016-01-01

Identity formation in adolescence is closely linked to searching for and acquiring meaning in one's life. To date little is known about the manner in which these 2 constructs may be related in this developmental stage. In order to shed more light on their longitudinal links, we conducted a 3-wave longitudinal study, investigating how identity…

An Acoustic Source Reactive to Tow Cable Strum

DTIC Science & Technology

2012-09-21

sound wave radiates from the head mass. Dkt . No. 101720 Application No. ?? REPLACEMENT SHEET? /3 DRAFT 1 CABLE CURVATURE INDUCING LONGITUDINAL...MOTION IDEALIZED TOW CABLE (NO TRANSVERSE VIBRATION) REALISTIC TOW CABLE (INCLUDES TRANSVERSE VIBRATION) DIRECTION OF TOW FIG. 1 (PRIOR ART) Dkt . No...DISPLACEMENT DISPLACEMENT LONGITUDINAL (PRIOR ART) DISPLACEMENT LONGITUDINAL Dkt . No. 101720 Application No. ?? REPLACEMENT SHEET? /3 DRAFT 10 A B B A

Effects of Maternal Parenting and Mother-Child Relationship Quality on Short-Term Longitudinal Change in Self-Regulation in Early Adolescence

ERIC Educational Resources Information Center

Moilanen, Kristin L.; Rambo-Hernandez, Karen E.

2017-01-01

The purpose of the present study was to explore the degree to which short-term longitudinal change in adolescent self-regulation was attributable to maternal parenting and mother-child relationship quality. A total of 821 mother-adolescent dyads provided data in the 1992 and 1994 waves of the Children of the National Longitudinal Survey of…

Effect of cross grain on stress waves in lumber

Treesearch

C.C. Gerhards

1980-01-01

An evaluation is made of the effect of cross grain on the transit time of longitudinal compression stress waves in Douglas-fir 2 by 8 lumber. Cross grain causes the stress wave to advance with a front or contour skewed in the direction of the grain angle, rather than to advance with a front normal to the long axis of lumber. Thus, the timing of the stress wave in...

Longitudinal Variation of the Lunar Tide in the Equatorial Electrojet

NASA Astrophysics Data System (ADS)

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.

Spectrum of spin waves in cold polarized gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreeva, T. L., E-mail: phdocandreeva@yandex.ru

2017-02-15

The spin dynamics of cold polarized gases are investigated using the Boltzmann equation. The dispersion relation for spin waves (transverse component of the magnetic moment) and the spin diffusion coefficient of the longitudinal component of the magnetic moment are calculated without using fitting parameters. The spin wave frequency and the diffusion coefficient for rubidium atoms are estimated numerically.

Emotion regulation predicts marital satisfaction: more than a wives' tale.

PubMed

Bloch, Lian; Haase, Claudia M; Levenson, Robert W

2014-02-01

Emotion regulation is generally thought to be a critical ingredient for successful interpersonal relationships. Ironically, few studies have investigated the link between how well spouses regulate emotion and how satisfied they are with their marriages. We utilized data from a 13-year, 3-wave longitudinal study of middle-aged (40-50 years old) and older (60-70 years old) long-term married couples, focusing on the associations between downregulation of negative emotion (measured during discussions of an area of marital conflict at Wave 1) and marital satisfaction (measured at all 3 waves). Downregulation of negative emotion was assessed by determining how quickly spouses reduced signs of negative emotion (in emotional experience, emotional behavior, and physiological arousal) after negative emotion events. Data were analyzed using actor-partner interdependence modeling. Findings showed that (a) greater downregulation of wives' negative experience and behavior predicted greater marital satisfaction for wives and husbands concurrently and (b) greater downregulation of wives' negative behavior predicted increases in wives' marital satisfaction longitudinally. Wives' use of constructive communication (measured between Waves 1 and 2) mediated the longitudinal associations. These results show the benefits of wives' downregulation of negative emotion during conflict for marital satisfaction and point to wives' constructive communication as a mediating pathway. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Quantitative Mapping of Pore Fraction Variations in Silicon Nitride Using an Ultrasonic Contact Scan Technique

NASA Technical Reports Server (NTRS)

Roth, Don J.; Kiser, James D.; Swickard, Suzanne M.; Szatmary, Steven A.; Kerwin, David P.

1993-01-01

An ultrasonic scan procedure using the pulse-echo contact configuration was employed to obtain maps of pore fraction variations in sintered silicon nitride samples in terms of ultrasonic material properties. Ultrasonic velocity, attenuation coefficient, and reflection coefficient images were obtained simultaneously over a broad band of frequencies (e.g., 30 to 110 MHz) by using spectroscopic analysis. Liquid and membrane (dry) coupling techniques and longitudinal and shear-wave energies were used. The major results include the following: Ultrasonic velocity (longitudinal and shear wave) images revealed and correlated with the extent of average through-thickness pore fraction variations in the silicon nitride disks. Attenuation coefficient images revealed pore fraction nonuniformity due to the scattering that occurred at boundaries between regions of high and low pore fraction. Velocity and attenuation coefficient images were each nearly identical for machined and polished disks, making the method readily applicable to machined materials. Velocity images were similar for wet and membrane coupling. Maps of apparent Poisson's ratio constructed from longitudinal and shear-wave velocities quantified Poisson's ratio variations across a silicon nitride disk. Thermal wave images of a disk indicated transient thermal behavior variations that correlated with observed variations in pore fraction and velocity and attenuation coefficients.

Selling and buying sex: a longitudinal study of risk and protective factors in adolescence.

PubMed

Kaestle, Christine E

2012-06-01

Engaging in trading sex is associated with many co-occurring problems, including elevated risk for sexually transmitted infections. Various dimensions of social support from parents, schools, and mentors may be protective against sex trading and may ameliorate the impact of risk factors. This study analyzes data from respondents to Waves I and III of the National Longitudinal Study of Adolescent Health (Add Health) who had not participated in sex trading for money or drugs in Wave I so that risk and protective factors for first initiations of selling or buying sex could be examined longitudinally. About 2% of the study sample began selling sex and about 2% began buying sex between Wave I and Wave III. The respondent's sex, race/ethnicity, history of sexual abuse, shoplifting, marijuana use, and experiences of homelessness or running away were significant predictors of trading sex (p < 0.05). Being happy at school was associated with lower selling of sex, and feeling part of school was associated with lower buying of sex even after controlling for demographics and risk factors (p < 0.05). Results indicate a need for early intervention for youth who experience sexual abuse or running away. Elements of school connectedness have a protective effect on selling and buying sex. Promoting school connectedness may advance public health goals.

Emotion regulation predicts marital satisfaction: More than a wives’ tale

PubMed Central

Bloch, Lian; Haase, Claudia M.; Levenson, Robert W.

2014-01-01

Emotion regulation is generally thought to be a critical ingredient for successful interpersonal relationships. Ironically, few studies have investigated the link between how well spouses regulate emotion and how satisfied they are with their marriages. We utilized data from a 13-year, 3-wave longitudinal study of middle-aged (40–50 years old) and older (60–70 years old) long-term married couples, focusing on the associations between downregulation of negative emotion (measured during discussions of an area of marital conflict at Wave 1) and marital satisfaction (measured at all three waves). Downregulation of negative emotion was assessed by determining how quickly spouses reduced signs of negative emotion (in emotional experience, emotional behavior, and physiological arousal) after negative emotion events. Data were analyzed using actor-partner interdependence modeling. Findings showed that (a) greater downregulation of wives’ negative experience and behavior predicted greater marital satisfaction for wives and husbands concurrently and (b) greater downregulation of wives’ negative behavior predicted increases in wives’ marital satisfaction longitudinally. Wives’ use of constructive communication (measured between Waves 1 and 2) mediated the longitudinal associations. These results show the benefits of wives’ downregulation of negative emotion during conflict for marital satisfaction and point to wives’ constructive communication as a mediating pathway. PMID:24188061

The prospective relationship between sleep problems and suicidal behavior in the National Longitudinal Study of Adolescent Health.

PubMed

Wong, Maria M; Brower, Kirk J

2012-07-01

Previous research has found a longitudinal relationship between sleep problems and suicidal behavior while controlling for depression and other important covariates in a high risk sample of adolescents and controls. In this paper, we replicated this longitudinal relationship in a national sample and examined whether the relationship was partially mediated by depression, alcohol-related problems and other drug use. Study participants were 6504 adolescents from the National Longitudinal Study of Adolescent Health (ADD HEALTH). In bivariate analyses, sleep problems (i.e., having trouble falling asleep or staying asleep) at Wave 1 were associated with suicidal thoughts and suicide attempts at Waves 1, 2, and 3 (W1, 2 and 3). In multivariate analyses, controlling for depression, alcohol problems, illicit drug use, and important covariates such as gender, age, and chronic health problems, sleep problems at a previous wave predicted suicidal thoughts and suicide attempts at a subsequent wave. In mediation analyses, W2 depression significantly mediated the effect of W1 sleep problems on W3 suicide thoughts. Moreover, W2 suicidal thoughts also significantly mediated the effect of W1 sleep problems on W3 suicidal attempts. Sleep problems appear to be a robust predictor of subsequent suicidal thoughts and attempts in adolescence and young adulthood. Having trouble falling sleeping or staying asleep had both direct and indirect effects (via depression and suicidal thoughts) on suicidal behavior. Future research could determine if early intervention with sleep disturbances reduces the risk for suicidality in adolescents and young adults. Copyright © 2012 Elsevier Ltd. All rights reserved.

The concurrent and longitudinal relationships between adolescents' use of social network sites and their social self-esteem.

PubMed

Valkenburg, Patti M; Koutamanis, Maria; Vossen, Helen G M

2017-11-01

The first aim of this study was to investigate the concurrent and longitudinal relationships between adolescents' use of social network sites (SNSs) and their social self-esteem. The second aim was to investigate whether the valence of the feedback that adolescents receive on SNSs can explain these relationships. We conducted a three-wave panel study among 852 pre- and early adolescents (10-15 years old). In line with earlier research, we found significant concurrent correlations between adolescents' SNS use and their social self-esteem in all three data waves. The longitudinal results only partly confirmed these concurrent findings: Adolescents' initial SNS use did not significantly influence their social self-esteem in subsequent years. In contrast, their initial social self-esteem consistently influenced their SNS use in subsequent years. The valence of online feedback from close friends and acquaintances explained the concurrent relationship between SNS use and social self-esteem, but not the longitudinal relationship. Results are discussed in terms of their methodological and theoretical implications.

A theoretical formulation of wave-vortex interactions

NASA Technical Reports Server (NTRS)

Wu, J. Z.; Wu, J. M.

1989-01-01

A unified theoretical formulation for wave-vortex interaction, designated the '(omega, Pi) framework,' is presented. Based on the orthogonal decomposition of fluid dynamic interactions, the formulation can be used to study a variety of problems, including the interaction of a longitudinal (acoustic) wave and/or transverse (vortical) wave with a main vortex flow. Moreover, the formulation permits a unified treatment of wave-vortex interaction at various approximate levels, where the normal 'piston' process and tangential 'rubbing' process can be approximated dfferently.

Development of a bi-directional standing wave linear piezoelectric actuator with four driving feet.

PubMed

Liu, Yingxiang; Shi, Shengjun; Li, Chunhong; Chen, Weishan; Wang, Liang; Liu, Junkao

2018-03-01

A bi-directional standing wave linear piezoelectric ultrasonic actuator with four driving feet is proposed in this work. Two sandwich type transducers operated in longitudinal-bending hybrid modes are set parallelly. The working mode of the transducer is not simple hybrid vibrations of a longitudinal one and a bending one, but a special coupling vibration mode contained both longitudinal and bending components. Two transducers with the same structure and unsymmetrical boundary conditions are set parallelly to accomplish the bi-directional driving: the first transducer can push the runner forward, while the other one produces the backward driving. In the experiments, two voltages with different amplitudes are applied on the two transducers, respectively: the one with higher voltage serves as the actuator, whereas the other one applied with lower voltage is used to reduce the frictional force. The prototype achieves maximum no-load speed and thrust force of 244 mm/s and 9.8 N. This work gives a new idea for the construction of standing wave piezoelectric ultrasonic actuator with bi-directional driving ability. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of the porosity on the dispersion of the phase velocity of longitudinal acoustic waves in isotropic metal-matrix composites

NASA Astrophysics Data System (ADS)

Karabutov, A. A.; Podymova, N. B.

2017-05-01

The influence of the volumetric porosity of isotropic metal-matrix composite materials, which are reinforced with ceramic microparticles, on the dispersion of the phase velocity of longitudinal acoustic waves is investigated. For this purpose, the method of broadband acoustic spectroscopy with a laser source of ultrasound and piezoelectric detection of nanosecond ultrasonic pulses is used. Composite samples based on a silumin matrix with added silicon carbide (SiC) microparticles in different mass concentrations (3.8-15.5%) were investigated. As the concentration of SiC particles in a sample increases, its porosity that is determined using the hydrostatic-weighing method also increases. The simultaneous increase in the filler concentration and porosity leads to the appearance of a dispersion of the phase velocity of longitudinal acoustic waves in the sample within the frequency range of 3-25 MHz. The obtained empirical relationship between the relative change in the phase velocity and the sample porosity can be used to obtain a proximate quantitative estimate of the bulk porosity of the isotropic metal-matrix composite materials.

Upstream-advancing waves generated by three-dimensional moving disturbances

NASA Astrophysics Data System (ADS)

Lee, Seung-Joon; Grimshaw, Roger H. J.

1990-02-01

The wave field resulting from a surface pressure or a bottom topography in a horizontally unbounded domain is studied. Upstream-advancing waves successively generated by various forcing disturbances moving with near-resonant speeds are found by numerically solving a forced Kadomtsev-Petviashvili (fKP) equation, which shows in its simplest form the interplay of a basic linear wave operator, longitudinal and transverse dispersion, nonlinearity, and forcing. Curved solitary waves are found as a slowly varying similarity solution of the Kadomtsev-Petviashvili (KP) equation, and are favorably compared with the upstream-advancing waves numerically obtained.

Playgroup Participation and Social Support Outcomes for Mothers of Young Children: A Longitudinal Cohort Study

PubMed Central

Hancock, Kirsten J.; Cunningham, Nadia K.; Lawrence, David; Zarb, David; Zubrick, Stephen R.

2015-01-01

Objective This study aimed to examine friendship networks and social support outcomes for mothers according to patterns of playgroup participation. Methods Data from the Longitudinal Study of Australian Children were used to examine the extent to which patterns of playgroup participation across the ages of 3–19 months (Wave 1) and 2–3 years (Wave 2) were associated with social support outcomes for mothers at Wave 3 (4–5 years) and four years later at Wave 5 (8–9 years). Analyses were adjusted for initial friendship attachments at Wave 1 and other socio-demographic characteristics. Results Log-binomial regression models estimating relative risks showed that mothers who never participated in a playgroup, or who participated at either Wave 1 or Wave 2 only, were 1.7 and 1.8 times as likely to report having no support from friends when the child was 4–5 years, and 2.0 times as likely to have no support at age 8–9 years, compared with mothers who persistently participated in playgroup at both Wave 1 and Wave 2. Conclusion These results provide evidence that persistent playgroup participation may acts as a protective factor against poor social support outcomes. Socially isolated parents may find playgroups a useful resource to build their social support networks. PMID:26181426

Fast decomposition of two ultrasound longitudinal waves in cancellous bone using a phase rotation parameter for bone quality assessment: Simulation study.

PubMed

Taki, Hirofumi; Nagatani, Yoshiki; Matsukawa, Mami; Kanai, Hiroshi; Izumi, Shin-Ichi

2017-10-01

Ultrasound signals that pass through cancellous bone may be considered to consist of two longitudinal waves, which are called fast and slow waves. Accurate decomposition of these fast and slow waves is considered to be highly beneficial in determination of the characteristics of cancellous bone. In the present study, a fast decomposition method using a wave transfer function with a phase rotation parameter was applied to received signals that have passed through bovine bone specimens with various bone volume to total volume (BV/TV) ratios in a simulation study, where the elastic finite-difference time-domain method is used and the ultrasound wave propagated parallel to the bone axes. The proposed method succeeded to decompose both fast and slow waves accurately; the normalized residual intensity was less than -19.5 dB when the specimen thickness ranged from 4 to 7 mm and the BV/TV value ranged from 0.144 to 0.226. There was a strong relationship between the phase rotation value and the BV/TV value. The ratio of the peak envelope amplitude of the decomposed fast wave to that of the slow wave increased monotonically with increasing BV/TV ratio, indicating the high performance of the proposed method in estimation of the BV/TV value in cancellous bone.

Estimation of True Change with Three-Wave Data.

ERIC Educational Resources Information Center

Gupta, J. K.; And Others

1988-01-01

A multiple regression model for estimating true change of an individual by using information in addition to pretest-posttest data is described. Longitudinal panel or multi-wave data taken between the pretest and the posttest constitute the additional information. (TJH)

The Dispersion of the Axisymmetric Longitudinal Waves in the Pre-Strained Bi-Material Hollow Cylinder with the Imperfect Interface Conditions

NASA Astrophysics Data System (ADS)

Akbarov, S. D.; Ipek, C.

This work studies the influence of the imperfectness of the interface conditions on the dispersion of the axisymmetric longitudinal waves in the pre-strained bi-material hollow cylinder. The investigations are made within the 3D linearized theory of elastic waves in elastic bodies with initial stresses. It is assumed that the materials of the layers of the hollow cylinder are made from hyper elastic compressible materials and the elasticity relations of those are given through the harmonic potential. The shear spring type imperfectness of the interface conditions is considered and the degree of this imperfectness is estimated by the shear-spring parameter. Numerical results on the influence of this parameter on the behavior of the dispersion curves are presented and discussed.

Health Benefits of Volunteering in the Wisconsin Longitudinal Study

ERIC Educational Resources Information Center

Piliavin, Jane Allyn; Siegl, Erica

2007-01-01

We investigate positive effects of volunteering on psychological well-being and self-reported health using all four waves of the Wisconsin Longitudinal Study. Confirming previous research, volunteering was positively related to both outcome variables. Both consistency of volunteering over time and diversity of participation are significantly…

Are Sibling Relationships Protective? A Longitudinal Study

ERIC Educational Resources Information Center

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…

Approximation method for a spherical bound system in the quantum plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehramiz, A.; Sobhanian, S.; Mahmoodi, J.

2010-08-15

A system of quantum hydrodynamic equations has been used for investigating the dielectric tensor and dispersion equation of a semiconductor as a quantum magnetized plasma. Dispersion relations and their modifications due to quantum effects are derived for both longitudinal and transverse waves. The number of states and energy levels are analytically estimated for a spherical bound system embedded in a semiconductor quantum plasma. The results show that longitudinal waves decay rapidly and do not interact with the spherical bound system. The energy shifts caused by the spin-orbit interaction and the Zeeman effect are calculated.

Stress-wave velocity of wood-based panels: effect of moisture, product type, and material direction

Treesearch

Guangping Han; Qinglin Wu; Xiping Wang

2006-01-01

The effect of moisture on longitudinal stress-wave velocity (SWV), bending stiffness. and bending strength of commercial oriented strandboard, plywood. particleboard. and southern pine lumber was evaluated. It was shown that the stress-wave verocity decreased in general with increases in panel moisture content (MC). At a given MC level. SWV varied with panel type and...

Stress Wave Propagation in Larch Plantation Trees-Numerical Simulation

Treesearch

Fenglu Liu; Fang Jiang; Xiping Wang; Houjiang Zhang; Wenhua Yu

2015-01-01

In this paper, we attempted to simulate stress wave propagation in virtual tree trunks and construct two dimensional (2D) wave-front maps in the longitudinal-radial section of the trunk. A tree trunk was modeled as an orthotropic cylinder in which wood properties along the fiber and in each of the two perpendicular directions were different. We used the COMSOL...

Fruit and vegetable intake, physical activity, and depressive symptoms in the African American Health (AAH) study.

PubMed

Ribeiro, Sandra M L; Malmstrom, Theodore K; Morley, John E; Miller, Douglas K

2017-10-01

Healthy diet and physical activity (PA) have been associated with reduced depressive symptoms, but few studies have examined them simultaneously in African Americans. To investigate fruit and vegetable intake (FVI) and PA as predictors of clinically-relevant levels of depressive symptoms (CRLDS) in African Americans. African American Health (AAH) is a population-based longitudinal study of African Americans in St. Louis, MO, who were born in 1936-1950 (inclusive) and empaneled in 2000-01 (wave 1). At wave 8, participants self-reported fruit and vegetable intake (FVI) and completed the Yale Physical Activity Scale. At both waves 8 and 10, the CES-D 11-item scale was used to identify those who met criteria for CRLDS. Sequential logistic regression modeling was used to examine the associations of components of FVI/PA with CRLDS, both cross-sectionally (n = 680, including imputed values) and longitudinally (n = 582, including imputed values). Modeling employed gender, age, perceived income adequacy, and education as potential confounders. Cross-sectionally, vigorous PA, and leisurely walking PA, were independently associated with lower odds of CRLDS in all but the fifth model and green vegetables in all models. Longitudinally, green vegetables and interactions between the FVI summary score, the PA summary score, and other factors at wave 8 were most consistently associated with CRLDS at wave 10. In both cross-sectional and longitudinal models, the socioeconomic variables showed the strongest association as risk factors for CRLDS. Both FVI and PA were self-reported rather than observed, our cohort had limited geographic- and age-ranges, and confidence intervals for some results were broad. Green vegetables, total FVI, and various aspects of PA showed protective effects regarding CRLDS. Therefore, the promotion of such lifestyles is likely to help prevent CRLDS in this population. Copyright © 2017. Published by Elsevier B.V.

Research on FBG-based longitudinal-acousto-optic modulator with Fourier mode coupling method.

PubMed

Li, Zhuoxuan; Pei, Li; Liu, Chao; Ning, Tigang; Yu, Shaowei

2012-10-20

Fourier mode coupling model was first applied to achieve the spectra property of a fiber Bragg grating (FBG)-based longitudinal-acousto-optic modulator. Compared with traditional analysis algorithms, such as the transfer matrix method, the Fourier mode coupling model could improve the computing efficiency up to 100 times with a guarantee of accuracy. In this paper, based on the theoretical analysis of this model, the spectra characteristics of the modulator in different frequencies and acoustically induced strains were numerically simulated. In the experiment, a uniform FBG was modulated by acoustic wave (AW) at 12 different frequencies. In particular, the modulator responses at 563 and 885.5 KHz with three different lead zirconate titanate (PZT) loads applied were plotted for illustration, and the linear fitting of experimental data demonstrated a good match with the simulation result. The acoustic excitation of the longitudinal wave is obtained using a conic silica horn attached to the surface of a shear-mode PZT plate paralleled to the fiber axis. This way of generating longitudinal AW with a transversal PZT may shed light on the optimal structural design for the FBG-based longitudinal-acousto-optic modulator.

A longitudinal, population-based twin study of avoidant and obsessive-compulsive personality disorder traits from early to middle adulthood

PubMed Central

Gjerde, L. C.; Czajkowski, N.; Røysamb, E.; Ystrom, E.; Tambs, K.; Aggen, S. H.; Ørstavik, R. E.; Kendler, K. S.; Reichborn-Kjennerud, T.; Knudsen, G. P.

2015-01-01

Background The phenotypic stability of avoidant personality disorder (AVPD) and obsessive-compulsive personality disorder (OCPD) has previously been found to be moderate. However, little is known about the longitudinal structure of genetic and environmental factors for these disorders separately and jointly, and to what extent genetic and environmental factors contribute to their stability. Method AVPD and OCPD criteria were assessed using the Structured Interview for DSM-IV Personality in 2793 young adult twins (1385 pairs, 23 singletons) from the Norwegian Institute of Public Health Twin Panel at wave 1 and 2282 (986 pairs, 310 singletons) of these on average 10 years later at wave 2. Longitudinal biometric models were fitted to AVPD and OCPD traits. Results For twins who participated at both time-points, the number of endorsed sub-threshold criteria for both personality disorders (PDs) decreased 31% from wave 1 to wave 2. Phenotypic correlations between waves were 0.54 and 0.37 for AVPD and OCPD, respectively. The heritability estimates of the stable PD liabilities were 0.67 for AVPD and 0.53 for OCPD. The genetic correlations were 1.00 for AVPD and 0.72 for OCPD, while the unique environmental influences correlated 0.26 and 0.23, respectively. The correlation between the stable AVPD and OCPD liabilities was 0.39 of which 63% was attributable to genetic influences. Shared environmental factors did not significantly contribute to PD variance at either waves 1 or 2. Conclusion Phenotypic stability was moderate for AVPD and OCPD traits, and genetic factors contributed more than unique environmental factors to the stability both within and across phenotypes. PMID:26273730

A longitudinal, population-based twin study of avoidant and obsessive-compulsive personality disorder traits from early to middle adulthood.

PubMed

Gjerde, L C; Czajkowski, N; Røysamb, E; Ystrom, E; Tambs, K; Aggen, S H; Ørstavik, R E; Kendler, K S; Reichborn-Kjennerud, T; Knudsen, G P

2015-12-01

The phenotypic stability of avoidant personality disorder (AVPD) and obsessive-compulsive personality disorder (OCPD) has previously been found to be moderate. However, little is known about the longitudinal structure of genetic and environmental factors for these disorders separately and jointly, and to what extent genetic and environmental factors contribute to their stability. AVPD and OCPD criteria were assessed using the Structured Interview for DSM-IV Personality in 2793 young adult twins (1385 pairs, 23 singletons) from the Norwegian Institute of Public Health Twin Panel at wave 1 and 2282 (986 pairs, 310 singletons) of these on average 10 years later at wave 2. Longitudinal biometric models were fitted to AVPD and OCPD traits. For twins who participated at both time-points, the number of endorsed sub-threshold criteria for both personality disorders (PDs) decreased 31% from wave 1 to wave 2. Phenotypic correlations between waves were 0.54 and 0.37 for AVPD and OCPD, respectively. The heritability estimates of the stable PD liabilities were 0.67 for AVPD and 0.53 for OCPD. The genetic correlations were 1.00 for AVPD and 0.72 for OCPD, while the unique environmental influences correlated 0.26 and 0.23, respectively. The correlation between the stable AVPD and OCPD liabilities was 0.39 of which 63% was attributable to genetic influences. Shared environmental factors did not significantly contribute to PD variance at either waves 1 or 2. Phenotypic stability was moderate for AVPD and OCPD traits, and genetic factors contributed more than unique environmental factors to the stability both within and across phenotypes.

The role of unhealthy lifestyles in the incidence and persistence of depression: a longitudinal general population study in four emerging countries.

PubMed

Cabello, Maria; Miret, Marta; Caballero, Francisco Felix; Chatterji, Somnath; Naidoo, Nirmala; Kowal, Paul; D'Este, Catherine; Ayuso-Mateos, Jose Luis

2017-03-20

Unhealthy lifestyles and depression are highly interrelated: depression might elicit and exacerbate unhealthy lifestyles and people with unhealthy lifestyles are more likely to become depressed over time. However, few longitudinal evidence of these relationships has been collected in emerging countries. The present study aims i) to analyse whether people with unhealthy lifestyles are more likely to develop depression, and ii) to examine whether depressed people with unhealthy lifestyles are more likely to remain depressed. A total of 7908 participants from Ghana, India, Mexico and Russia were firstly evaluated in the World Health Organization's Study on Global AGEing and Adult Health (SAGE) Wave 0 (2002-2004) and re-evaluated in 2007-2010 (Wave 1). Data on tobacco use, alcohol drinking and physical activity, were collected. Logistic regressions models were employed to assess whether baseline unhealthy lifestyles were related to depression in Wave 1, among people without 12-month depression in Wave 0 and any previous lifetime diagnosis of depression, and to 12-month depression at both study waves (persistent depression). Baseline daily and non-daily smoking was associated with depression in Wave 1. Low physical activity and heavy alcohol drinking were associated with persistent depression. Unhealthy lifestyles and depression are also positively related in emerging countries. Smoking on a daily and non-daily basis was longitudinally related to depression. Depressed people with low physical activity and with heavy drinking patterns were more likely to become depressed over time. Several interpretations of these results are given. Further studies should check whether a reduction of these unhealthy lifestyles leads to lower depression rates and/or to a better clinical prognosis of depressed people.

Alternative Approaches to Assessing Nonresponse Bias in Longitudinal Survey Estimates: An Application to Substance-Use Outcomes Among Young Adults in the United States

PubMed Central

West, Brady Thomas; McCabe, Sean Esteban

2017-01-01

Abstract We evaluated alternative approaches to assessing and correcting for nonresponse bias in a longitudinal survey. We considered the changes in substance-use outcomes over a 3-year period among young adults aged 18–24 years (n = 5,199) in the United States, analyzing data from the National Epidemiologic Survey on Alcohol and Related Conditions. This survey collected a variety of substance-use information from a nationally representative sample of US adults in 2 waves: 2001–2002 and 2004–2005. We first considered nonresponse rates in the second wave as a function of key substance-use outcomes in wave 1. We then evaluated 5 alternative approaches designed to correct for nonresponse bias under different attrition mechanisms, including weighting adjustments, multiple imputation, selection models, and pattern-mixture models. Nonignorable attrition in a longitudinal survey can lead to bias in estimates of change in certain health behaviors over time, and only selected procedures enable analysts to assess the sensitivity of their inferences to different assumptions about the extent of nonignorability. We compared estimates based on these 5 approaches, and we suggest a road map for assessing the risk of nonresponse bias in longitudinal studies. We conclude with directions for future research in this area given the results of our evaluations. PMID:28338839

Early School Transitions and the Social Behavior of Children with Disabilities: Selected Findings from the Pre-Elementary Education Longitudinal Study. Wave 3 Overview Report from the Pre-Elementary Education Longitudinal Study (PEELS). NCSER 2009-3016

ERIC Educational Resources Information Center

Carlson, Elaine; Daley, Tamara; Bitterman, Amy; Heinzen, Harriotte; Keller, Brad; Markowitz, Joy; Riley, Jarnee

2009-01-01

The Pre-Elementary Education Longitudinal Study (PEELS), funded by the U.S. Department of Education, is examining the characteristics of children receiving preschool special education, the services they receive, their transitions across educational levels, and their performance over time on assessments of academic and adaptive skills. PEELS…

Space-Charge Waves and Instabilities in Intense Beams

NASA Astrophysics Data System (ADS)

Wang, J. G.

1997-11-01

Advancced accelerator applications, such as drivers for heavy ion inertial fusion, high-intensity synchrotrons for spallation neutron sources, high energy boosters, free electron lasers, high-power microwave generators, etc., require ever-increasing beam intensity. An important beam dynamics issue in such beams is the collective behavior of charged particles due to their space charge effects. This includes the phenomena of space-charge waves and instabilities excited on beams by external perturbations. It is very crucial to fully understand these phenomena in order to develop advanced accelerators for various applications. At the University of Maryland we have been conducting experimental programs to study space-charge waves and longitudinal instabilities by employing low-energy, high-current, space-charge dominated electron beams. Localized perturbations on the beams are generated from a gridded electron gun. In a conducting transport channel focused by short solenoids, these perturbations evolve into space-charge waves propagating on the beams. The wave speed is measured and many beam parameters are determined with this technique. The reflection of space-charge waves at the shoulder of an initially rectangular beam bunch is also observed. In a resistive-wall channel focused by a uniform long solenoid, the space-charge waves suffer longitudinal instability. The properties of the instabilities are studied in detail in the long wavelength range. In this talk we review our experimental results on the waves and instabilities and compare with theory.

Gender differences in the causal direction between workplace harassment and drinking.

PubMed

Freels, Sally A; Richman, Judith A; Rospenda, Kathleen M

2005-08-01

Data from a longitudinal study of university employees across four waves is used to determine the extent to which workplace harassment predicts drinking or conversely the extent to which drinking predicts workplace harassment, and to address gender differences in these relationships. Mixed effects regression models are used to test the effects of 1) harassment at the previous wave on drinking at the current wave, adjusting for drinking at the previous wave, and 2) drinking at the previous wave on harassment at the current wave, adjusting for harassment at the previous wave. For males, drinking at the previous wave predicts sexual harassment at the current wave, whereas for females, sexual harassment at the previous wave predicts drinking at the current wave.

Acoustic transducer for acoustic microscopy

DOEpatents

Khuri-Yakub, Butrus T.; Chou, Ching H.

1990-01-01

A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

Self-consistent Langmuir waves in resonantly driven thermal plasmas

NASA Astrophysics Data System (ADS)

Lindberg, R. R.; Charman, A. E.; Wurtele, J. S.

2007-12-01

The longitudinal dynamics of a resonantly driven Langmuir wave are analyzed in the limit that the growth of the electrostatic wave is slow compared to the bounce frequency. Using simple physical arguments, the nonlinear distribution function is shown to be nearly invariant in the canonical particle action, provided both a spatially uniform term and higher-order spatial harmonics are included along with the fundamental in the longitudinal electric field. Requirements of self-consistency with the electrostatic potential yield the basic properties of the nonlinear distribution function, including a frequency shift that agrees closely with driven, electrostatic particle simulations over a range of temperatures. This extends earlier work on nonlinear Langmuir waves by Morales and O'Neil [G. J. Morales and T. M. O'Neil, Phys. Rev. Lett. 28, 417 (1972)] and Dewar [R. L. Dewar, Phys. Plasmas 15, 712 (1972)], and could form the basis of a reduced kinetic treatment of plasma dynamics for accelerator applications or Raman backscatter.

Sexual Identity Mobility and Depressive Symptoms: A Longitudinal Analysis of Sexual Minority Women

PubMed Central

Everett, Bethany; Talley, Amelia; Hughes, Tonda; Wilsnack, Sharon; Johnson, Timothy P.

2016-01-01

Sexual minority identity (bisexual, lesbian) is a known risk factor for depression in women. This study examines a facet of minority stress prevalent among women—sexual identity mobility—as an identity-related contributor to higher levels of depressive symptoms. We used three waves of data from the Chicago Health and Life Experiences of Women (CHLEW) study, a longitudinal study of sexual minority women (N = 306). Random effects OLS regression models were constructed to examine the effect of sexual-identity changes on depressive symptoms. We found that 25.6% of the sample reported a sexual-identity change between Wave I and Wave II, and 24.91% reported a sexual identity change between Waves II and III. Women who reported a change in sexual identity also reported more depressive symptoms subsequent to identity change. This effect was moderated by the number of years participants’ had reported their baseline identity and by whether the participant had initiated a romantic relationship with a male partner. PMID:27255306

Experimental study and finite element analysis based on equivalent load method for laser ultrasonic measurement of elastic constants.

PubMed

Zhan, Yu; Liu, Changsheng; Zhang, Fengpeng; Qiu, Zhaoguo

2016-07-01

The laser ultrasonic generation of Rayleigh surface wave and longitudinal wave in an elastic plate is studied by experiment and finite element method. In order to eliminate the measurement error and the time delay of the experimental system, the linear fitting method of experimental data is applied. The finite element analysis software ABAQUS is used to simulate the propagation of Rayleigh surface wave and longitudinal wave caused by laser excitation on a sheet metal sample surface. The equivalent load method is proposed and applied. The pulsed laser is equivalent to the surface load in time and space domain to meet the Gaussian profile. The relationship between the physical parameters of the laser and the load is established by the correction factor. The numerical solution is in good agreement with the experimental result. The simple and effective numerical and experimental methods for laser ultrasonic measurement of the elastic constants are demonstrated. Copyright © 2016. Published by Elsevier B.V.

An Ultrasonic Technique to Determine the Residual Strength of Adhesive Bonds

NASA Technical Reports Server (NTRS)

Achenbach, J. D.; Tang, Z.

1999-01-01

In this work, ultrasonic techniques to nondestructively evaluate adhesive bond degradation have been studied. The key to the present approach is the introduction of an external factor which pulls the adhesive bond in the nonlinear range, simultaneously with the application of an ultrasonic technique. With the aid of an external static tensile loading, a superimposed longitudinal wave has.been used to obtain the slopes of the stress-strain curve of an adhesive bond at a series of load levels. The critical load, at which a reduction of the slope is detected by the superimposed longitudinal wave, is an indication of the onset of nonlinear behavior of the adhesive bond, and therefore of bond degradation. This approach has been applied to the detection of adhesive bond degradation induced by cyclic fatigue loading. Analogously to the longitudinal wave case, a superimposed shear wave has been used to obtain the effective shear modulus of adhesive layers at different shear load levels. The onset of the nonlinear behavior of an adhesive bond under shear loading has been detected by the use of a superimposed shear wave. Experiments show that a longitudinal wave can also detect the nonlinear behavior when an adhesive bond is subjected to shear loading. An optimal combination of ultrasonic testing and mechanical loading methods for the detection of degradation related nonlinear behavior of adhesive bonds has been discussed. For the purpose of a practical application, an ultrasonic technique that uses a temperature increase as an alternative to static loading has also been investigated. A general strain-temperature correspondence principle that relates a mechanical strain to a temperature has been presented. Explicit strain-temperature correspondence relations for both the tension and shear cases have been derived. An important parameter which quantifies the relation between the wave velocity and temperature has been defined. This parameter, which is indicative of adhesive bond nonlinearity and which can be conveniently obtained by an ultrasonic measurement, has been used as an indication of adhesive bond degradation. Experimental results have shown that the temperature increase method is a convenient and productive alternative to static loading. A technique which uses the reflected waveform data to obtain the fundamental ultrasonic parameters (transit time, reflection coefficient and attenuation coefficient) of an adhesive bond has also been presented.

Longitudinal and Circumferential Strain of the Proximal Aorta

PubMed Central

Bell, Vanessa; Mitchell, William A.; Sigurðsson, Sigurður; Westenberg, Jos J. M.; Gotal, John D.; Torjesen, Alyssa A.; Aspelund, Thor; Launer, Lenore J.; de Roos, Albert; Gudnason, Vilmundur; Harris, Tamara B.; Mitchell, Gary F.

2014-01-01

Background Accurate assessment of mechanical properties of the proximal aorta is a requisite first step for elucidating the pathophysiology of isolated systolic hypertension. During systole, substantial proximal aortic axial displacement produces longitudinal strain, which we hypothesize causes variable underestimation of ascending aortic circumferential strain compared to values in the longitudinally constrained descending aorta. Methods and Results To assess effects of longitudinal strain, we performed magnetic resonance imaging in 375 participants (72 to 94 years old, 204 women) in the Age, Gene/Environment Susceptibility‐Reykjavik Study and measured aortic circumferential and longitudinal strain. Circumferential ascending aortic area strain uncorrected for longitudinal strain was comparable in women and men (mean [95% CI], 8.3 [7.8, 8.9] versus 7.9 [7.4, 8.5]%, respectively, P=0.3). However, longitudinal strain was greater in women (8.5±2.5 versus 7.0±2.5%, P<0.001), resulting in greater longitudinally corrected circumferential ascending aortic strain (14.4 [13.6, 15.2] versus 13.0 [12.4, 13.7]%, P=0.010). Observed circumferential descending aortic strain, which did not require correction (women: 14.0 [13.2, 14.8], men: 12.4 [11.6, 13.2]%, P=0.005), was larger than uncorrected (P<0.001), but comparable to longitudinally corrected (P=0.12) circumferential ascending aortic strain. Carotid‐femoral pulse wave velocity did not correlate with uncorrected ascending aortic strain (R=−0.04, P=0.5), but was inversely related to longitudinally corrected ascending and observed descending aortic strain (R=−0.15, P=0.004; R=−0.36, P<0.001, respectively). Longitudinal strain was also inversely related to carotid‐femoral pulse wave velocity and other risk factors for higher aortic stiffness including treated hypertension. Conclusions Longitudinal strain creates substantial and variable errors in circumferential ascending aortic area strain measurements, particularly in women, and should be considered to avoid misclassification of ascending aortic stiffness. PMID:25523153

Optical Production and Detection of Ultrasonic Waves in Metals for Nondestructive Testing

NASA Technical Reports Server (NTRS)

Morrison, R. A.

1972-01-01

Ultrasonic waves were produced by striking the surface of a metal with the focused one-joule pulse of a Q-switched ruby laser. Rayleigh (surface) waves and longitudinal waves were detected with conventional transducers. Optical methods of detection were tested and developed. Rayleigh waves were produced with an oscillator and transducer. They were optically detected on curved polished surfaces, and on unpolished surfaces. The technique uses a knife edge to detect small angle changes of the surface as the wave pulse passes the illuminated spot. Optical flaw detection using pulse echo and attenuation is demonstrated.

Analysis of limited-diffractive and limited-dispersive X-waves generated by finite radial waveguides

NASA Astrophysics Data System (ADS)

Fuscaldo, Walter; Pavone, Santi C.; Valerio, Guido; Galli, Alessandro; Albani, Matteo; Ettorre, Mauro

2016-05-01

In this work, we analyze the spatial and temporal features of electromagnetic X-waves propagating in free space and generated by planar radiating apertures. The performance of ideal X-waves is discussed and compared to practical cases where the important effects related to the finiteness of the radiating aperture and the wavenumber dispersion are taken into account. In particular, a practical device consisting of a radial waveguide loaded with radiating slots aligned along a spiral path is considered for the practical case in the millimeter-wave range. A common mathematical framework is defined for a precise comparison of the spatiotemporal properties and focusing capabilities of the generated X-wave. It is clearly shown that the fractional bandwidth of the radiating aperture has a key role in the longitudinal confinement of an X-wave in both ideal and practical cases. In addition, the finiteness of the radiating aperture as well as the wavenumber dispersion clearly affect both the transverse and the longitudinal profiles of the generated radiation as it travels beyond the depth-of-field of the generated X-wave. Nevertheless, the spatiotemporal properties of the X-wave are preserved even in this "dispersive-finite" case within a defined region and duration related to the nondiffractive range and fractional bandwidth of the spectral components of the generated X-wave. The proposed analysis may open new perspectives for the efficient generation of X-waves over finite radiating apertures at millimeter waves where the dispersive behavior of realistic devices is no longer negligible.

Bulk solitary waves in elastic solids

NASA Astrophysics Data System (ADS)

Samsonov, A. M.; Dreiden, G. V.; Semenova, I. V.; Shvartz, A. G.

2015-10-01

A short and object oriented conspectus of bulk solitary wave theory, numerical simulations and real experiments in condensed matter is given. Upon a brief description of the soliton history and development we focus on bulk solitary waves of strain, also known as waves of density and, sometimes, as elastic and/or acoustic solitons. We consider the problem of nonlinear bulk wave generation and detection in basic structural elements, rods, plates and shells, that are exhaustively studied and widely used in physics and engineering. However, it is mostly valid for linear elasticity, whereas dynamic nonlinear theory of these elements is still far from being completed. In order to show how the nonlinear waves can be used in various applications, we studied the solitary elastic wave propagation along lengthy wave guides, and remarkably small attenuation of elastic solitons was proven in physical experiments. Both theory and generation for strain soliton in a shell, however, remained unsolved problems until recently, and we consider in more details the nonlinear bulk wave propagation in a shell. We studied an axially symmetric deformation of an infinite nonlinearly elastic cylindrical shell without torsion. The problem for bulk longitudinal waves is shown to be reducible to the one equation, if a relation between transversal displacement and the longitudinal strain is found. It is found that both the 1+1D and even the 1+2D problems for long travelling waves in nonlinear solids can be reduced to the Weierstrass equation for elliptic functions, which provide the solitary wave solutions as appropriate limits. We show that the accuracy in the boundary conditions on free lateral surfaces is of crucial importance for solution, derive the only equation for longitudinal nonlinear strain wave and show, that the equation has, amongst others, a bidirectional solitary wave solution, which lead us to successful physical experiments. We observed first the compression solitary wave in the duct-like polymer shell and proved, that there is no tensile area behind the wave, the bulk soliton propagates on a distance many times longer than its wave length, while both its shape and amplitude remain unchanged. We demonstrated recently how the strain solitons can be used for non-destructive testing (NDT) of laminated composites, used nowadays for various applications, e.g., in microelectronics, aerospace and automotive industries, and bulk strain solitons are among prospective instruments for NDT. Being aimed to propose the bulk strain solitons as an instrument for NDT in solids, we studied numerically the evolution of them in various wave guides with local defects, and shown that the strain soliton undergoes changes in amplitude, phase shift and the shape, that are distinctive and can be estimated. To sum up, now we are able to propose a new NDT technique, based on bulk strain soliton propagation in structural elements.

Coherent electromagnetic waves in the presence of a half space of randomly distributed scatterers

NASA Technical Reports Server (NTRS)

Karam, M. A.; Fung, A. K.

1988-01-01

The present investigation of coherent field propagation notes, upon solving the Foldy-Twersky integral equation for a half-space of small spherical scatterers illuminated by a plane wave at oblique incidence, that the coherent field for a horizontally-polarized incident wave exhibits reflectivity and transmissivity consistent with the Fresnel formula for an equivalent continuous effective medium. In the case of a vertically polarized incident wave, both the vertical and longitudinal waves obtained for the coherent field have reflectivities and transmissivities that do not agree with the Fresnel formula.

Energy density and energy flow of surface waves in a strongly magnetized graphene

NASA Astrophysics Data System (ADS)

Moradi, Afshin

2018-01-01

General expressions for the energy density and energy flow of plasmonic waves in a two-dimensional massless electron gas (as a simple model of graphene) are obtained by means of the linearized magneto-hydrodynamic model and classical electromagnetic theory when a strong external magnetic field perpendicular to the system is present. Also, analytical expressions for the energy velocity, wave polarization, wave impedance, transverse and longitudinal field strength functions, and attenuation length of surface magneto-plasmon-polariton waves are derived, and numerical results are prepared.

Identification of acoustic waves in ZnO materials by Brillouin light scattering for SAW device applications

NASA Astrophysics Data System (ADS)

Zerdali, M.; Bechiri, F.; Hamzaoui, S.; Teherani, F. H.; Rogers, D. J.; Sandana, V. E.; Bove, P.; Djemia, P.; Roussigné, Y.

2017-03-01

Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films grown by pulsed laser deposition. The bulk ZnO crystals presented both longitudinal and transverse bulk acoustic waves. Theoretical calculations agreed well with there being one piezoelectric longitudinal branch and two transverse branches. BLS measurements conducted on ZnO thin films also revealed Rayleigh surface acoustic waves (R-SAW) guided by only the surface of the layer and Sezawa modes, guided by the film thickness. Measurements were conducted for three incidence angles in order to investigate different SAW wave numbers. Higher frequency features were identified as being related to a new class of guided longitudinal (LG) SAW modes which are not usually detected for ZnO thin films. The LG-SAW modes were observed for two incidence angles (θ=45° and 55°) corresponding to frequencies of 17.88 and 20.75 GHz, respectively. BLS measurements enable us to estimate the LG-SAW velocity as 6500 m/s. This value is three times higher than that of the currently used R-SAW. Theoretical simulations were coherent with the presence of LG modes in the ZnO layers. Such LG-SAW modes are promising for the development of novel, higher-speed SAW devices operating in the GHz-band and which could be readily incorporated in Si-based integrated circuitry.

Numerical evaluation of longitudinal motions of Wigley hulls advancing in waves by using Bessho form translating-pulsating source Green'S function

NASA Astrophysics Data System (ADS)

Xiao, Wenbin; Dong, Wencai

2016-06-01

In the framework of 3D potential flow theory, Bessho form translating-pulsating source Green's function in frequency domain is chosen as the integral kernel in this study and hybrid source-and-dipole distribution model of the boundary element method is applied to directly solve the velocity potential for advancing ship in regular waves. Numerical characteristics of the Green function show that the contribution of local-flow components to velocity potential is concentrated at the nearby source point area and the wave component dominates the magnitude of velocity potential in the far field. Two kinds of mathematical models, with or without local-flow components taken into account, are adopted to numerically calculate the longitudinal motions of Wigley hulls, which demonstrates the applicability of translating-pulsating source Green's function method for various ship forms. In addition, the mesh analysis of discrete surface is carried out from the perspective of ship-form characteristics. The study shows that the longitudinal motion results by the simplified model are somewhat greater than the experimental data in the resonant zone, and the model can be used as an effective tool to predict ship seakeeping properties. However, translating-pulsating source Green function method is only appropriate for the qualitative analysis of motion response in waves if the ship geometrical shape fails to satisfy the slender-body assumption.

Religious participation is associated with increases in religious social support in a national longitudinal study of African Americans

PubMed Central

Le, Daisy; Holt, Cheryl L.; Hosack, Dominic P.; Huang, Jin; Clark, Eddie M.

2015-01-01

Objective This study reports on the association between religious beliefs and behaviors and the change in both general and religious social support using two waves of data from a national sample of African Americans. Design The Religion and Health in African Americans (RHIAA) study is a longitudinal telephone survey designed to examine relationships between various aspects of religious involvement and psychosocial factors over time. Participants RHIAA participants were 3,173 African American men (1,281) and women (1,892). A total of 1,251 men (456) and women (795) participated in wave 2 of data collection. Results Baseline religious behaviors were associated with increased overall religious social support from baseline to wave 2 (p<.001) and with increased religious social support from baseline to wave 2 in each of the following religious social support subscales: emotional support received (p<.001), emotional support provided (p<.001), negative interaction (p<.001), and anticipated support (p<.001). Religious beliefs did not predict change in any type of support, and neither beliefs nor behaviors predicted change in general social support. Conclusions African Americans who are active in faith communities showed increases in all types of religious social support, even the negative aspects, over a relatively modest longitudinal study period. This illustrates the strength of the church as a social network and the role that it plays in people’s lives. PMID:26493343

Religious Participation is Associated with Increases in Religious Social Support in a National Longitudinal Study of African Americans.

PubMed

Le, Daisy; Holt, Cheryl L; Hosack, Dominic P; Huang, Jin; Clark, Eddie M

2016-08-01

This study reports on the association between religious beliefs and behaviors and the change in both general and religious social support using two waves of data from a national sample of African Americans. The Religion and Health in African Americans (RHIAA) study is a longitudinal telephone survey designed to examine relationships between various aspects of religious involvement and psychosocial factors over time. RHIAA participants were 3173 African American men (1281) and women (1892). A total of 1251 men (456) and women (795) participated in wave 2 of data collection. Baseline religious behaviors were associated with increased overall religious social support from baseline to wave 2 (p < .001) and with increased religious social support from baseline to wave 2 in each of the following religious social support subscales: emotional support received (p < .001), emotional support provided (p < .001), negative interaction (p < .001), and anticipated support (p < .001). Religious beliefs did not predict change in any type of support, and neither beliefs nor behaviors predicted change in general social support. African Americans who are active in faith communities showed increases in all types of religious social support, even the negative aspects, over a relatively modest longitudinal study period. This illustrates the strength of the church as a social network and the role that it plays in people's lives.

Predictors and Sequelae of Fractures in the Elderly: The Canadian Study of Health and Aging (CSHA)

ERIC Educational Resources Information Center

Ostbye, Truls; Walton, Ruth E.; Steenhuis, Runa; Hodsman, Anthony B.

2004-01-01

The objective of this study was to describe the incidence, type, risk factors, and sequelae of fractures experienced by community-dwelling elderly Canadians. Data are from the Canadian Study of Health and Aging (CSHA), a longitudinal cohort study, collected in three waves: baseline (1991), wave 2 (1996), and wave 3 (2001). In CSHA-2 (1996),…

Acoustic parametric pumping of spin waves

NASA Astrophysics Data System (ADS)

Keshtgar, Hedyeh; Zareyan, Malek; Bauer, Gerrit E. W.

2014-11-01

Recent experiments demonstrated generation of spin currents by ultrasound. We can understand this acoustically induced spin pumping in terms of the coupling between magnetization and lattice waves. Here we study the parametric excitation of magnetization by longitudinal acoustic waves and calculate the acoustic threshold power. The induced magnetization dynamics can be detected by the spin pumping into an adjacent normal metal that displays the inverse spin Hall effect.

Circle of life: rationale, design, and baseline results of an HIV prevention intervention among young American Indian adolescents of the Northern Plains.

PubMed

Kaufman, Carol E; Mitchell, Christina M; Beals, Janette; Desserich, Jennifer A; Wheeler, Cindy; Keane, Ellen M; Whitesell, Nancy Rumbaugh; Sam, Angela; Sedey, Cory

2010-03-01

In spite of significant disparities in sexual health outcomes for American Indian youth, no studies exist examining the effectiveness of HIV-prevention interventions. Circle of Life is an HIV-prevention intervention specifically developed for American Indian middle-school youth. We describe the rationale, methodology, and baseline results of a longitudinal randomized trial of Circle of Life conducted among American Indian youth aged 11-15 in a reservation community. The innovative design includes two pre-intervention waves to determine patterns of behavior prior to the intervention that might be associated with a differential impact of the intervention on sexual risk. We used one-way analysis of variance and chi-square tests to test for significant differences between randomized group assignment at each baseline wave and generalized estimating equations (GEE) to test significant differences in the rate of change in outcomes by group longitudinally. We present the collaborative and adaptive strategies for consenting, assenting, and data collection methodology in this community. Achieved response rates are comparable to other similar studies. Results from the two baseline waves indicate that few outcomes significantly varied by randomized intervention assignment. Ten percent of youth reported having had sex at Wave 1, rising to 15% at Wave 2. Among those who had had sex, the majority (>70%) reported using a condom at last sex. The project is well positioned to carry out the longitudinal assessments of the intervention to determine the overall impact of the Circle of Life and the differential impact by pre-intervention patterns of behavior across youth.

Happiness as a motivator: positive affect predicts primary control striving for career and educational goals.

PubMed

Haase, Claudia M; Poulin, Michael J; Heckhausen, Jutta

2012-08-01

What motivates individuals to invest time and effort and overcome obstacles (i.e., strive for primary control) when pursuing important goals? We propose that positive affect predicts primary control striving for career and educational goals, and we explore the mediating role of control beliefs. In Study 1, positive affect predicted primary control striving for career goals in a two-wave longitudinal study of a U.S. sample. In Study 2, positive affect predicted primary control striving for career and educational goals and objective career outcomes in a six-wave longitudinal study of a German sample. Control beliefs partially mediated the longitudinal associations with primary control striving. Thus, when individuals experience positive affect, they become more motivated to invest time and effort, and overcome obstacles when pursuing their goals, in part because they believe they have more control over attaining their goals.

Motivation Mediates the Perfectionism-Burnout Relationship: A Three-Wave Longitudinal Study With Junior Athletes.

PubMed

Madigan, Daniel J; Stoeber, Joachim; Passfield, Louis

2016-08-01

Perfectionism in sports has been shown to predict longitudinal changes in athlete burnout. What mediates these changes over time, however, is still unclear. Adopting a self-determination theory perspective and using a three-wave longitudinal design, the current study examined perfectionistic strivings, perfectionistic concerns, autonomous motivation, controlled motivation, and athlete burnout in 141 junior athletes (mean age = 17.3 years) over 6 months of active training. When multilevel structural equation modeling was employed to test a mediational model, a differential pattern of between- and within-person relationships emerged. Whereas autonomous motivation mediated the negative relationship that perfectionistic strivings had with burnout at the between- and within-person level, controlled motivation mediated the positive relationship that perfectionistic concerns had with burnout at the between-persons level only. The present findings suggest that differences in autonomous and controlled motivation explain why perfectionism predicts changes in athlete burnout over time.

Scatter of elastic waves by a thin flat elliptical inhomogeneity

NASA Technical Reports Server (NTRS)

Fu, L. S.

1983-01-01

Elastodynamic fields of a single, flat, elliptical inhomogeneity embedded in an infinite elastic medium subjected to plane time harmonic waves are studied. Scattered displacement amplitudes and stress intensities are obtained in series form for an incident wave in an arbitrary direction. The cases of a penny shaped crack and an elliptical crack are given as examples. The analysis is valid for alpha a up to about two, where alpha is longitudinal wave number and a is a typical geometric parameter.

Gender Differences in the Content of Preschool Children's Recollections: A Longitudinal Study

ERIC Educational Resources Information Center

Tõugu, Pirko; Tulviste, Tiia; Suits, Kristi

2014-01-01

Personal recollections constitute autobiographical memory that develops intensively during the preschool years. The two-wave longitudinal study focuses on gender differences in preschool children's independent recollections. The same children (N = 275; 140 boys, 135 girls) were asked to talk about their previous birthday and the past weekend at…

Discrepancies Confer Vulnerability to Depressive Symptoms: A Three-Wave Longitudinal Study

ERIC Educational Resources Information Center

Sherry, Simon B.; Mackinnon, Sean P.; Macneil, Matthew A.; Fitzpatrick, Skye

2013-01-01

Discrepancies (i.e., a subjective sense of falling short of one's own standards) are a key part of the perfectionism construct. Theory suggests discrepancies confer vulnerability to depressive symptoms. Since most research in this area is cross-sectional, longitudinal research is needed to disentangle directionality of relationships and to permit…

Bidirectional Longitudinal Relations between Father-Child Relationships and Chinese Children's Social Competence during Early Childhood

ERIC Educational Resources Information Center

Zhang, Xiao

2013-01-01

Using a two-year and three-wave cross-lagged design with a sample of 118 Chinese preschoolers, the present study examined bidirectional longitudinal relations between father-child relationships and children's social competence. The results of structural equation modeling showed bidirectional effects between father-child conflict and social…

The Third Wave of Longitudinal Data Systems: Data Partnerships

ERIC Educational Resources Information Center

Armstrong, Jane; Bergner, Terry; Smith, Nancy

2008-01-01

States have made dramatic progress in the past few years in implementing longitudinal data systems (LDS) to improve student achievement. These systems collect and house student educational data that make it easy for policymakers and practitioners to access and use it for reporting, policymaking and decision making. So much has happened in states…

Temperament, Parenting, and South Korean Early Adolescents' Physical Aggression: A Five-Wave Longitudinal Analysis

ERIC Educational Resources Information Center

Lee, Julie

2014-01-01

Objective: This study examined the growth pattern in physical aggression over a five-year period among South Korean early adolescents and the effects of temperament (anger/frustration and emotion regulation) and parenting (harsh parenting and parental monitoring) on early adolescents' physical aggression. Design: A five-year longitudinal design…

Achievement Emotions and Academic Performance: Longitudinal Models of Reciprocal Effects

ERIC Educational Resources Information Center

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…

The Role of Acculturative Stress on Mental Health Symptoms for Immigrant Adolescents: A Longitudinal Investigation

ERIC Educational Resources Information Center

Sirin, Selcuk R.; Ryce, Patrice; Gupta, Taveeshi; Rogers-Sirin, Lauren

2013-01-01

Immigrant-origin adolescents represent the fastest growing segment of youth population in the United States, and in many urban schools they represent the majority of students. In this 3-wave longitudinal study, we explored trajectories of internalizing mental health symptoms (depression, anxiety, and somatic symptoms). The participants included…

Changes in Domain Specific Self-Perception amongst Young People with Intellectual Disability: A Longitudinal Study

ERIC Educational Resources Information Center

O'Byrne, Clara; Muldoon, Orla T.

2018-01-01

This study examines the changes that occur in multidimensional self-concept of adolescents with a diagnosis of intellectual disabilities, across gender and category of intellectual disability (borderline, mild, moderate) groups. A sample of 54 young people completed the Harter Self-Perception Profile. Using a three-wave longitudinal study…

A Longitudinal Analysis of Television Advertising Effects on Adolescents.

ERIC Educational Resources Information Center

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…

The Importance of Additive Reasoning in Children's Mathematical Achievement: A Longitudinal Study

ERIC Educational Resources Information Center

Ching, Boby Ho-Hong; Nunes, Terezinha

2017-01-01

This longitudinal study examines the relative importance of counting ability, additive reasoning, and working memory in children's mathematical achievement (calculation and story problem solving). In Hong Kong, 115 Chinese children aged 6 years old participated in 2 waves of assessments (T1 = first grade and T2 = second grade). Multiple regression…

A Chinese Longitudinal Study on Work/Family Enrichment

ERIC Educational Resources Information Center

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,…

Longitudinal terahertz wave generation from an air plasma filament induced by a femtosecond laser

NASA Astrophysics Data System (ADS)

Minami, Yasuo; Kurihara, Takayuki; Yamaguchi, Keita; Nakajima, Makoto; Suemoto, Tohru

2013-04-01

We have generated and detected a longitudinally polarized (Z-polarized) terahertz (THz) wave by focusing a conically propagating THz beam generated from a plasma filament induced by a femtosecond laser pulse. In the experiment, we observed a radially polarized field in a collimated region and Z-polarized field at focus in the time domain. The maximum value of the Z-polarized THz electric field reached 1.0 kV/cm. It was also quantitatively discussed about the Z-polarized field and the radial field at the focal point. We expect this technique to find application in THz time domain spectroscopy.

Computational Investigation of Helical Traveling Wave Tube Transverse RF Field Forces

NASA Technical Reports Server (NTRS)

Kory, Carol L.; Dayton, James A.

1998-01-01

In a previous study using a fully three-dimensional (3D) helical slow-wave circuit cold- test model it was found, contrary to classical helical circuit analyses, that transverse FF electric fields have significant amplitudes compared with the longitudinal component. The RF fields obtained using this helical cold-test model have been scaled to correspond to those of an actual TWT. At the output of the tube, RF field forces reach 61%, 26% and 132% for radial, azimuthal and longitudinal components, respectively, compared to radial space charge forces indicating the importance of considering them in the design of electron beam focusing.

A model for longitudinal and shear wave propagation in viscoelastic media

PubMed

Szabo; Wu

2000-05-01

Relaxation models fail to predict and explain loss characteristics of many viscoelastic materials which follow a frequency power law. A model based on a time-domain statement of causality is presented that describes observed power-law behavior of many viscoelastic materials. A Hooke's law is derived from power-law loss characteristics; it reduces to the Hooke's law for the Voigt model for the specific case of quadratic frequency loss. Broadband loss and velocity data for both longitudinal and shear elastic types of waves agree well with predictions. These acoustic loss models are compared to theories for loss mechanisms in dielectrics based on isolated polar molecules and cooperative interactions.

Lattice dynamics of colloidal crystals

NASA Astrophysics Data System (ADS)

Hurd, Alan J.; Clark, Noel A.; Mockler, Richard C.; O'Sullivan, William J.

1982-11-01

Photon correlation spectroscopy was performed on a dilute bcc colloidal crystal in a thin-film cell to measure its response to thermal fluctuations with wave vectors along lattice symmetry directions. The phonon dispersion curves show a definite harmonic-lattice behavior for longitudinal and transverse modes. We present a Langevin treatment of the lattice dynamics, based on harmonic potentials and a theory of hydrodynamic interactions which is exact to lowest order in sphere volume fraction and includes important unsteady flow effects. The model takes into consideration the discreteness of the lattice, which is important near the Brillouin-zone boundary, and has the correct behavior for long-wavelength fluctuations as well (underdamped transverse modes, overdamped longitudinal modes). The mass renormalization of propagating transverse lattice modes is discussed, along with the effects of the thin-film configuration on their propagation. The role of backflow in overdamping longitudinal modes is made clear. From the measured dispersion curves for longitudinal wave vectors, we obtained the following elastic constants: c11=6.96 dyn/cm2 and c12=c44=2.43 dyn/cm2.

Electric generator

DOEpatents

Foster, Jr., John S.; Wilson, James R.; McDonald, Jr., Charles A.

1983-01-01

1. In an electrical energy generator, the combination comprising a first elongated annular electrical current conductor having at least one bare surface extending longitudinally and facing radially inwards therein, a second elongated annular electrical current conductor disposed coaxially within said first conductor and having an outer bare surface area extending longitudinally and facing said bare surface of said first conductor, the contiguous coaxial areas of said first and second conductors defining an inductive element, means for applying an electrical current to at least one of said conductors for generating a magnetic field encompassing said inductive element, and explosive charge means disposed concentrically with respect to said conductors including at least the area of said inductive element, said explosive charge means including means disposed to initiate an explosive wave front in said explosive advancing longitudinally along said inductive element, said wave front being effective to progressively deform at least one of said conductors to bring said bare surfaces thereof into electrically conductive contact to progressively reduce the inductance of the inductive element defined by said conductors and transferring explosive energy to said magnetic field effective to generate an electrical potential between undeformed portions of said conductors ahead of said explosive wave front.

Longitudinal and latitudinal variations in dynamic characteristics of the MLT (70-95km): a study involving the CUJO network

NASA Astrophysics Data System (ADS)

Manson, A.; Meek, C.; Chshyolkova, T.; Avery, S.; Thorsen, D.; MacDougall, J.; Hocking, W.; Murayama, Y.; Igarashi, K.; Namboothiri, S.; Kishore, P.

2004-02-01

. The newly-installed MFR (medium frequency radar) at Platteville (40N, 105W) has provided the opportunity and impetus to create an operational network of middle- latitude MFRs stretching from W-E. CUJO (Canada U.S. Japan Opportunity) comprises systems at London (N, 81W), Platteville (40N, 105W), Saskatoon (52N, 107W), Wakkanai (45N, 142E) and Yamagawa (31N, 131E). It offers a significant 7000km longitudinal sector in the North American-Pacific region, and a useful range of latitudes (12-14) at two longitudes. Annual climatologies involving both height and frequency versus time contour plots for periods from 8h to 30 days, show that the changes with longitude are very significant and distinctive, often exceeding the local latitudinal variations. Comparisons with models and the recent UARS-HRDI global analysis of tides are discussed. The fits of the horizontal wave numbers of the longer period oscillations are provided in unique frequency versus time contour plots and shown to be consistent with the expected dominant modes. Annual climatologies of planetary waves (16 day, 2 day) and gravity waves reveal strong seasonal and longitudinal variations.

On possible plume-guided seismic waves

USGS Publications Warehouse

Julian, B.R.; Evans, J.R.

2010-01-01

Hypothetical thermal plumes in the Earth's mantle are expected to have low seismic-wave speeds and thus would support the propagation of guided elastic waves analogous to fault-zone guided seismic waves, fiber-optic waves, and acoustic waves in the oceanic SOund Fixing And Ranging channel. Plume-guided waves would be insensitive to geometric complexities in the wave guide, and their dispersion would make them distinctive on seismograms and would provide information about wave-guide structure that would complement seismic tomography. Detecting such waves would constitute strong evidence of a new kind for the existence of plumes. A cylindrical channel embedded in an infinite medium supports two classes of axially symmetric elastic-wave modes, torsional and longitudinal-radial. Torsional modes have rectilinear particle motion tangent to the cylinder surface. Longitudinal-radial modes have elliptical particle motion in planes that include the cylinder axis, with retrograde motion near the axis. The direction of elliptical particle motion reverses with distance from the axis: once for the fundamental mode, twice for the first overtone, and so on. Each mode exists only above its cut-off frequency, where the phase and group speeds equal the shear-wave speed in the infinite medium. At high frequencies, both speeds approach the shear-wave speed in the channel. All modes have minima in their group speeds, which produce Airy phases on seismograms. For shear wave-speed contrasts of a few percent, thought to be realistic for thermal plumes in the Earth, the largest signals are inversely dispersed and have dominant frequencies of about 0.1-1 Hz and durations of 15-30 sec. There are at least two possible sources of observable plume waves: (1) the intersection of mantle plumes with high-amplitude core-phase caustics in the deep mantle; and (2) ScS-like reflection at the core-mantle boundary of downward-propagating guided waves. The widespread recent deployment of broadband seismometers makes searching for these waves possible.

Acoustic transducer for acoustic microscopy

DOEpatents

Khuri-Yakub, B.T.; Chou, C.H.

1990-03-20

A shear acoustic transducer-lens system is described in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens. 9 figs.

Temperature maxima in stable two-dimensional shock waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kum, O.; Hoover, W.G.; Hoover, C.G.

1997-07-01

We use molecular dynamics to study the structure of moderately strong shock waves in dense two-dimensional fluids, using Lucy{close_quote}s pair potential. The stationary profiles show relatively broad temperature maxima, for both the longitudinal and the average kinetic temperatures, just as does Mott-Smith{close_quote}s model for strong shock waves in dilute three-dimensional gases. {copyright} {ital 1997} {ital The American Physical Society}

Student Characteristics and Behaviors at Age 12 Predict Occupational Success 40 Years Later over and above Childhood IQ and Parental Socioeconomic Status

ERIC Educational Resources Information Center

Spengler, Marion; Brunner, Martin; Damian, Rodica I.; Lüdtke, Oliver; Martin, Romain; Roberts, Brent W.

2015-01-01

Drawing on a 2-wave longitudinal sample spanning 40 years from childhood (age 12) to middle adulthood (age 52), the present study was designed to examine how student characteristics and behaviors in late childhood (assessed in Wave 1 in 1968) predict career success in adulthood (assessed in Wave 2 in 2008). We examined the influence of parental…

Relations between Political Violence and Child Adjustment: A Four-Wave Test of the Role of Emotional Insecurity about Community

ERIC Educational Resources Information Center

Cummings, E. Mark; Taylor, Laura K.; Merrilees, Christine E.; Goeke-Morey, Marcie C.; Shirlow, Peter; Cairns, Ed

2013-01-01

This study further explored the impact of sectarian violence and children's emotional insecurity about community on child maladjustment using a 4-wave longitudinal design. The study included 999 mother-child dyads in Belfast, Northern Ireland (482 boys, 517 girls). Across the 4 waves, child mean age was 12.19 (SD = 1.82), 13.24 (SD = 1.83), 13.61…

The relationship between study addiction and work addiction: A cross-cultural longitudinal study.

PubMed

Atroszko, Paweł A; Andreassen, Cecilie Schou; Griffiths, Mark D; Pallesen, Ståle

2016-12-01

Aims Recent empirical studies investigating "study addiction" have conceptualized it as a behavioral addiction, defined within the framework of work addiction. This study is the first attempt to examine the longitudinal relationship between study addiction and work addiction. Methods The Bergen Study Addiction Scale (BStAS), the Bergen Work Addiction Scale (BWAS), and the Ten-Item Personality Inventory were administered online together with questions concerning demographics and study-related variables in two waves. In Wave 1, a total of 2,559 students in Norway and 2,177 students in Poland participated. A year later, in Wave 2, 379 Norwegians and 401 Polish who began to work professionally completed the survey. Results The intraclass correlation between BStAS and BWAS revealed that the scores were somewhat related; however, the relationship was slightly weaker than the temporal stability of both constructs. In the Norwegian sample, scoring higher on neuroticism and lower on learning time outside educational classes in Wave 1 was positively related to work addiction in Wave 2, whereas gender was unrelated to work addiction in Wave 2 when controlling for other studied variables in either samples. Conclusion Study addiction and work addiction appear to be closely related suggesting that the former may be a precursor for (or an early form of) the latter.

The relationship between study addiction and work addiction: A cross-cultural longitudinal study

PubMed Central

Atroszko, Paweł A.; Andreassen, Cecilie Schou; Griffiths, Mark D.; Pallesen, Ståle

2016-01-01

Aims Recent empirical studies investigating “study addiction” have conceptualized it as a behavioral addiction, defined within the framework of work addiction. This study is the first attempt to examine the longitudinal relationship between study addiction and work addiction. Methods The Bergen Study Addiction Scale (BStAS), the Bergen Work Addiction Scale (BWAS), and the Ten-Item Personality Inventory were administered online together with questions concerning demographics and study-related variables in two waves. In Wave 1, a total of 2,559 students in Norway and 2,177 students in Poland participated. A year later, in Wave 2, 379 Norwegians and 401 Polish who began to work professionally completed the survey. Results The intraclass correlation between BStAS and BWAS revealed that the scores were somewhat related; however, the relationship was slightly weaker than the temporal stability of both constructs. In the Norwegian sample, scoring higher on neuroticism and lower on learning time outside educational classes in Wave 1 was positively related to work addiction in Wave 2, whereas gender was unrelated to work addiction in Wave 2 when controlling for other studied variables in either samples. Conclusion Study addiction and work addiction appear to be closely related suggesting that the former may be a precursor for (or an early form of) the latter. PMID:27842448

Adolescent risk factors for purging in young women: findings from the national longitudinal study of adolescent health

PubMed Central

2014-01-01

Background There exists a dearth of prospective adolescent eating disorder studies with samples that are large enough to detect small or medium sized effects for risk factors, that are generalizable to the broader population, and that follow adolescents long enough to fully capture the period of development when the risk of eating disorder symptoms occurring is highest. As a result, the purpose of this study was to examine psychosocial risk factors for purging for weight control in a nationally representative sample of adolescents. Data were extracted from the restricted-use data sets of the National Longitudinal Study of Adolescent Health (Waves I-III), selecting females with valid demographic and purging information (N = 5,670). Results The prevalence of purging was 0.88% at Wave II and 0.56% at Wave III. In multivariable multinomial logistic regressions, purging at Wave II was predicted by parental poverty and low levels of self-esteem at Wave I; purging at Wave III was predicted by body mass index and the frequency of delinquent behaviors at Wave I. Conclusions Individuals with high body mass index, individuals with low self-esteem, and individuals in families experiencing economic hardship appear specifically at risk for the development of purging behaviors in later years and may benefit from more targeted prevention efforts. PMID:24999424

Adolescent same-sex and both-sex romantic attractions and relationships: implications for smoking.

PubMed

Easton, Alyssa; Jackson, Kat; Mowery, Paul; Comeau, Dawn; Sell, Randall

2008-03-01

We examined cross-sectional and longitudinal associations between smoking and romantic attractions and relationships. We used data from the National Longitudinal Study of Adolescent Health to assess associations of smoking at Waves I and II with same-sex, both-sex, and opposite-sex romantic attractions or relationships as determined at Wave I. We used logistic regression to predict smoking at Wave II by sexual orientation. Both adolescent boys and adolescent girls with both-sex attractions or relationships were significantly more likely than those with opposite-sex attractions or relationships to be current smokers. Adolescent boys and girls with both-sex attractions or relationships who were nonsmokers at Wave I were more likely to be current smokers at Wave II than those with opposite-sex attractions or relationships. Our findings support previous research on smoking among youths who report same-sex or both-sex romantic attractions or relationships and demonstrate the increased risk bisexual youths have for smoking initiation and smoking prevalence. Tobacco use prevention programs targeting gay and bisexual youths are warranted, particularly among adolescent girls and boys who have had both-sex romantic attractions or relationships.

Adolescent Same-Sex and Both-Sex Romantic Attractions and Relationships: Implications for Smoking

PubMed Central

Easton, Alyssa; Jackson, Kat; Mowery, Paul; Comeau, Dawn; Sell, Randall

2008-01-01

Objectives. We examined cross-sectional and longitudinal associations between smoking and romantic attractions and relationships. Methods. We used data from the National Longitudinal Study of Adolescent Health to assess associations of smoking at Waves I and II with same-sex, both-sex, and opposite-sex romantic attractions or relationships as determined at Wave I. We used logistic regression to predict smoking at Wave II by sexual orientation. Results. Both adolescent boys and adolescent girls with both-sex attractions or relationships were significantly more likely than those with opposite-sex attractions or relationships to be current smokers. Adolescent boys and girls with both-sex attractions or relationships who were nonsmokers at Wave I were more likely to be current smokers at Wave II than those with opposite-sex attractions or relationships. Conclusions. Our findings support previous research on smoking among youths who report same-sex or both-sex romantic attractions or relationships and demonstrate the increased risk bisexual youths have for smoking initiation and smoking prevalence. Tobacco use prevention programs targeting gay and bisexual youths are warranted, particularly among adolescent girls and boys who have had both-sex romantic attractions or relationships. PMID:18235075

The density of alcohol outlets and adolescent alcohol consumption: An Australian longitudinal analysis.

PubMed

Rowland, B; Evans-Whipp, Tracy; Hemphill, Sheryl; Leung, Rachel; Livingston, M; Toumbourou, J W

2016-01-01

Higher density of alcohol outlets has been linked to increased levels of adolescent alcohol-related behaviour. Research to date has been cross-sectional. A longitudinal design using two waves of annual survey data from the Australian arm of the International Youth Development Study was used. The sample comprised 2835 individuals with average age at wave 2 of 14 years (SD=1.67; range=11-17 years). GSEM was used to examine how absolute levels of alcohol outlet density was associated with student-reported alcohol use one year later, while controlling for prior alcohol use, risk factors at wave one and changes in density over the 2 years. Adolescents' perception of alcohol availability and friends' alcohol use were tested as potential mediators of the association between alcohol outlet density and adolescent alcohol use. Elasticity modelling identified a 10% increase in overall density at wave one was associated with an approximately 17% increase in odds of adolescent alcohol consumption at wave two. Living in areas with a higher density of outlets was associated with a statistically significant increase in the likelihood of adolescents developing early age alcohol consumption. Copyright © 2015 Elsevier Ltd. All rights reserved.

Four-peak longitudinal distribution of the equatorial plasma bubbles observed in the topside ionosphere: Possible troposphere tide influence

NASA Astrophysics Data System (ADS)

Sidorova, L. N.; Filippov, S. V.

2018-03-01

In this paper we consider an idea of the troposphere tide influence on the character of the longitudinal variations in the distribution of the equatorial plasma bubbles (EPBs) observed in the topside ionosphere. For this purpose, the obtained EPB longitudinal patterns were compared with the thermosphere and ionosphere characteristics having the prominent "wave-like" longitudinal structures with wave number 4, which are uniquely associated with the influence of the troposphere DE3 tides. The characteristics of the equatorial mass density anomaly (EMA), equatorial ionization anomaly (EIA), zonal wind and pre-reversal E × B drift enhancement (PRE) were used for comparison. The equinox seasons during high solar activity were under consideration. It was obtained that the longitudinal patterns of the EMA and zonal wind show the surprising similarity with the EPB distributions (R ≅ 0.8, R ≅ 0.72). On the other hand, the resemblance with the ionosphere characteristics (EIA, PRE) is rather faint (R ≅ 0.37, R ≅ 0.12). It was shown that the thermosphere zonal winds are the most possible transfer mediator of the troposphere DE3 tide influence. The most successful moment for the transfer of the troposphere DE3 tide energy takes place in the beginning of the EPB production, namely, during the seed perturbation development.

Ultrasonic transient bounded-beam propagation in a solid cylinder waveguide embedded in a solid medium.

PubMed

Laguerre, Laurent; Grimault, Anne; Deschamps, Marc

2007-04-01

A semianalytical solution alternative and complementary to modal technique is presented to predict and interpret the ultrasonic pulsed-bounded-beam propagation in a solid cylinder embedded in a solid matrix. The spectral response to an inside axisymmetric velocity source of longitudinal and transversal cylindrical waves is derived from Debye series expansion of the embedded cylinder generalized cylindrical reflection/transmission coefficients. So, the transient guided wave response, synthesized by inverse double Fourier-Bessel transform, is expressed as a combination of the infinite medium contribution, longitudinal, transversal, and coupled longitudinal and transversal waveguide sidewall interactions. Simulated (f, 1/lambdaz) diagrams show the influence of the number of waveguide sidewall interactions to progressively recover dispersion curves. Besides, they show the embedding material filters specific signal portions by concentrating the propagating signal in regions where phase velocity is closer to phase velocity in steel. Then, simulated time waveforms using broadband high-frequency excitation show that signal leading portions exhibit a similar periodical pattern, for both free and embedded waveguides. Debye series-based interpretation shows that double longitudinal/transversal and transversal/longitudinal conversions govern the time waveform leading portion as well as the radiation attenuation in the surrounding cement grout. Finally, a methodology is deduced to minimize the radiation attenuation for the long-range inspection of embedded cylinders.

940  mW 1564  nm multi-longitudinal-mode and 440  mW 1537  nm single-longitudinal-mode continuous-wave Er:Yb:Lu2Si2O7 microchip lasers.

PubMed

Huang, Jianhua; Chen, Yujin; Lin, Yanfu; Gong, Xinghong; Luo, Zundu; Huang, Yidong

2018-04-15

An Er:Yb:Lu 2 Si 2 O 7 microchip laser was constructed by placing a 1.2 mm thick, Y-cut Er:Yb:Lu 2 Si 2 O 7 microchip between two 1.2 mm thick sapphire crystals, in which input and output mirrors were directly deposited onto one face of each crystal. End-pumped by a continuous-wave 975.4 nm diode laser, a 1564 nm multi-longitudinal-mode laser with a maximum output power of 940 mW and slope efficiency of 20% was realized at an absorbed pump power of 5.5 W when the transmission of output mirror was 2.2%. When the transmission of the output mirror was increased to 6%, a 1537 nm single-longitudinal-mode laser with a maximum output power of 440 mW and slope efficiency of 12% was realized at an absorbed pump power of 4.3 W. The results indicate that the Er:Yb:Lu 2 Si 2 O 7 crystal is a promising microchip gain medium to realize a single-longitudinal-mode laser.

Generation of propagating backward volume spin waves by phase-sensitive mode conversion in two-dimensional microstructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braecher, T.; Sebastian, T.; Graduate School Materials Science in Mainz, Gottlieb-Daimler-Strasse 47, D-67663 Kaiserslautern

2013-04-01

We present the generation of propagating backward volume (BV) spin waves in a T shaped Ni{sub 81}Fe{sub 19} microstructure. These waves are created from counterpropagating Damon Eshbach spin waves, which are excited using microstrip antennas. By employing Brillouin light scattering microscopy, we show how the phase relation between the counterpropagating waves determines the mode generated in the center of the structure, and prove its propagation inside the longitudinally magnetized part of the T shaped microstructure. This gives access to the effective generation of backward volume spin waves with full control over the generated transverse mode.

High-frequency Oscillations in Small Magnetic Elements Observed with Sunrise/SuFI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jafarzadeh, S.; Solanki, S. K.; Cameron, R. H.

2017-04-01

We characterize waves in small magnetic elements and investigate their propagation in the lower solar atmosphere from observations at high spatial and temporal resolution. We use the wavelet transform to analyze oscillations of both horizontal displacement and intensity in magnetic bright points found in the 300 nm and the Ca ii H 396.8 nm passbands of the filter imager on board the Sunrise balloon-borne solar observatory. Phase differences between the oscillations at the two atmospheric layers corresponding to the two passbands reveal upward propagating waves at high frequencies (up to 30 mHz). Weak signatures of standing as well as downward propagating waves are alsomore » obtained. Both compressible and incompressible (kink) waves are found in the small-scale magnetic features. The two types of waves have different, though overlapping, period distributions. Two independent estimates give a height difference of approximately 450 ± 100 km between the two atmospheric layers sampled by the employed spectral bands. This value, together with the determined short travel times of the transverse and longitudinal waves provide us with phase speeds of 29 ± 2 km s{sup −1} and 31 ± 2 km s{sup −1}, respectively. We speculate that these phase speeds may not reflect the true propagation speeds of the waves. Thus, effects such as the refraction of fast longitudinal waves may contribute to an overestimate of the phase speed.« less

Desistance from intimate partner violence: the role of legal cynicism, collective efficacy, and social disorganization in Chicago neighborhoods.

PubMed

Emery, Clifton R; Jolley, Jennifer M; Wu, Shali

2011-12-01

This paper examined the relationship between reported Intimate Partner Violence (IPV) desistance and neighborhood concentrated disadvantage, ethnic heterogeneity, residential instability, collective efficacy and legal cynicism. Data from the Project on Human Development in Chicago Neighborhoods (PHDCN) Longitudinal survey were used to identify 599 cases of IPV in Wave 1 eligible for reported desistance in Wave 2. A Generalized Boosting Model was used to determine the best proximal predictors of IPV desistance from the longitudinal data. Controlling for these predictors, logistic regression of neighborhood characteristics from the PHDCN community survey was used to predict reported IPV desistance in Wave 2. The paper finds that participants living in neighborhoods high in legal cynicism have lower odds of reporting IPV desistance, controlling for other variables in the logistic regression model. Analyses did not find that IPV desistance was related to neighborhood concentrated disadvantage, ethnic heterogeneity, residential instability and collective efficacy.

Factor structure of DSM-5 PTSD symptoms in trauma-exposed adolescents: Examining stability across time.

PubMed

Wang, Li; Cao, Xing; Cao, Chengqi; Fang, Ruojiao; Yang, Haibo; Elhai, Jon D

2017-12-01

This study investigated the latent structure of DSM-5 PTSD symptoms using two-wave longitudinal data collected from a sample of adolescents exposed to an explosion accident. Two waves of surveys were conducted approximately 3 and 8 months after the accident, respectively. A total of 836 students completed the baseline survey, and 762 students completed the follow-up survey. The results of confirmatory factor analyses(CFA) indicated that a seven-factor hybrid model composed of intrusion, avoidance, negative affect, anhedonia, externalizing behaviors, anxious arousal and dysphoric arousal factors yielded significantly better data fit at both waves than the other models including the DSM-5 four-factor model, the six-factor anhedonia and externalizing behaviors models. Furthermore, the results of CFA invariance tests supported the longitudinal invariance of the model. Implications and limitations in terms of these results are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

The relationship of major depressive disorder and gender to changes in smoking for current and former smokers: Longitudinal evaluation in the U.S. population

PubMed Central

Weinberger, Andrea H.; Pilver, Corey E.; Desai, Rani A.; Mazure, Carolyn M.; McKee, Sherry A.

2012-01-01

Aims Although depression and smoking are highly correlated, the relationship of Major Depressive Disorder (MDD) to smoking cessation and relapse remains unclear. This study compared changes in smoking for current and former smokers with and without Current and Lifetime MDD over a three year period. Design Analysis of two waves of longitudinal data from the National Institute on Alcohol Abuse and Alcoholism’s National Epidemiologic Survey on Alcohol and Related Conditions (Wave 1, 2001–2002; Wave 2, 2004–2005). Setting Data were collected through face-to-face interviews from non-institutionalized United States civilians, 18 years and older, in 50 states and the District of Columbia. Participants 11,973 adults (46% female) classified as Current or Former Daily Smokers at Wave 1 and completed Wave 2. Measurements Classification as Current or Former Smokers at Wave 1 and Wave 2. Findings Smoking status remained stable for most participants. Wave 1 Current Daily Smokers with Current MDD (OR=1.38, 95% CI=1.03, 1.85) and Lifetime MDD (OR=1.48, 95% CI=1.18, 1.85) were more likely than those without the respective diagnosis to report continued smoking at Wave 2. Wave 1 Former Daily Smokers with Current MDD (OR=0.44, 95% CI=0.26, 0.76) were less likely to report continued abstinence at Wave 2. None of the gender by MDD diagnosis interactions were significant. Patterns of results remained similar when analyses were limited to smokers with nicotine dependence. Conclusions Current and Lifetime Major Depressive Disorder are associated with a lower likelihood of quitting smoking and Current Major Depressive Disorder is associated with greater likelihood of smoking relapse. PMID:22429388

Photoacoustic method for measuring concentration of chemical species

DOEpatents

Autrey, S Thomas [West Richland, WA; Posakony, Gerald J [Richland, WA; Amonette, James E [Richland, WA; Foster-Mills, Nancy S [Richland, WA

2001-01-01

The present invention is a transducer for photoacoustic detection having at least two piezoelectric elements wherein at least a first piezoelectric element has a first frequency and at least a second piezoelectric element has a second frequency. The improvement according to the present invention is that at least two piezoelectric elements are longitudinal elements for longitudinal waves; and the first frequency is different from said second frequency. In other words, the invention is a multi-frequency longitudinal transducer for photoacoustic detection.

Piezoelectric shear wave resonator and method of making same

DOEpatents

Wang, Jin S.; Lakin, Kenneth M.; Landin, Allen R.

1988-01-01

An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppm/.degree.C.

Method of making a piezoelectric shear wave resonator

DOEpatents

Wang, Jin S.; Lakin, Kenneth M.; Landin, Allen R.

1987-02-03

An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppm/.degree.C.

Individual payments as a longer-term incentive in online panels.

PubMed

Göritz, Anja S; Wolff, Hans-Georg; Goldstein, Daniel G

2008-11-01

Does it pay to pay online panel members? A three-wave longitudinal experiment was conducted with an online panel to examine whether per person payments, paid through an online intermediary, influence response and retention rates. In the payment condition, participants were promised payment for participation at each wave, whereas control participants were not offered any payment. The promise of a payment had a negative effect on response in Wave 1, but a positive effect on response in Wave 2. Payment had no significant effect on retention. Completing a given wave was an indicator for responding to a subsequent invitation.

Emotional Intelligence throughout Portuguese Secondary School: A Longitudinal Study Comparing Performance and Self-Report Measures

ERIC Educational Resources Information Center

Costa, Ana; Faria, Luísa

2016-01-01

This study examines the developmental trajectories of ability and trait emotional intelligence (EI) in the Portuguese secondary school. Within a three-wave longitudinal design, 395 students (M[subscript age] = 15.4; SD = 0.74) completed both the Emotional Skills and Competence Questionnaire (ESCQ) and the Vocabulary of Emotions Test (VET). Results…

Identity Processes and Coping Strategies in College Students: Short-Term Longitudinal Dynamics and the Role of Personality

ERIC Educational Resources Information Center

Luyckx, Koen; Klimstra, Theo A.; Duriez, Bart; Schwartz, Seth J.; Vanhalst, Janne

2012-01-01

Coping strategies and identity processes are hypothesized to influence one another over time. This three-wave longitudinal study ("N" = 458; 84.9% women) examined, for the first time, how and to what extent identity processes (i.e., commitment making, identification with commitment, exploration in breadth, exploration in depth, and ruminative…

Friendship Quality and School Achievement: A Longitudinal Analysis during Primary School

ERIC Educational Resources Information Center

Zucchetti, Giulia; Candela, Filippo; Sacconi, Beatrice; Rabaglietti, Emanuela

2015-01-01

This study examined the longitudinal relationship between friendship quality (positive and negative) and school achievement among 228 school-age children (51% girls, M = 8.09, SD = 0.41). A three-wave cross-lagged analysis was used to determine the direction of influence between these domains across school years. Findings revealed that: (a) school…

Sexually Transmitted Infections and Unintended Pregnancy: A Longitudinal Analysis of Risk Transmission through Friends and Attitudes

ERIC Educational Resources Information Center

Henry, David B.; Deptula, Daneen P.; Schoeny, Michael E.

2012-01-01

Data from 1,087 adolescent participants in three waves of the National Longitudinal Study of Adolescent Health were used to examine the effects of peer selection and socialization processes in adolescence on later reports of sexually transmitted infections (STI) and unintended pregnancies. Friends' attitudes and behavior were assessed with…

Why Is Cancer More Depressing for Men than Women among Older White Adults?

ERIC Educational Resources Information Center

Pudrovska, Tetyana

2010-01-01

Using data from two waves of the Wisconsin Longitudinal Study (N = 8,054), I examine gender differences in psychological adjustment to cancer among older white adults. Results from different types of longitudinal models reveal that cancer has more adverse psychological implications for men than women. Men's higher levels of depression are reduced…

Initiation and Continuation of Best Friends and Adolescents' Alcohol Consumption: Do Self-Esteem and Self-Control Function as Moderators?

ERIC Educational Resources Information Center

Larsen, Helle; Overbeek, Geertjan; Vermulst, Ad A.; Granic, Isabela; Engels, Rutger C. M. E.

2010-01-01

In this three-wave longitudinal survey, we investigated bi-directional longitudinal associations between best friends and adolescents' alcohol consumption. Additionally, since the relation between best friends and adolescents' drinking may be stronger if adolescents have not consumed alcohol yet, we examined this relation not only with regard to…

Heavy Metal and Hip-Hop Style Preferences and Externalizing Problem Behavior: A Two-Wave Longitudinal Study

ERIC Educational Resources Information Center

Selfhout, Maarten H. W.; Delsing, Marc J. M. H.; ter Bogt, Tom F. M.; Meeus, Wim H. J.

2008-01-01

This study examines (a) the stability of Dutch adolescents' preferences for heavy metal and hip-hop youth culture styles, (b) longitudinal associations between their preferences and externalizing problem behavior, and (c) the moderating role of gender in these associations. Questionnaire data were gathered from 931 adolescents between the ages of…

Prediction of ultrasonic properties from grain angle

Treesearch

M.F. Kabir

2001-01-01

The ultrasonic properties of rubber wood were evaluated in three main symmetry axes – longitudinal (L), radial (R) and tangential direction and also at an angle rotating from the symmetry axes at different moisture content. The ultrasonic velocity were determined with a commercial ultrasonic tester of 45 kHz pulsed longitudinal waves. The experimental results were...

Online Communication, Compulsive Internet Use, and Psychosocial Well-Being among Adolescents: A Longitudinal Study

ERIC Educational Resources Information Center

van den Eijnden, Regina J. J. M.; Meerkerk, Gert-Jan; Vermulst, Ad A.; Spijkerman, Renske; Engels, Rutger C. M. E.

2008-01-01

The present study investigated the relationships between adolescents' online communication and compulsive Internet use, depression, and loneliness. The study had a 2-wave longitudinal design with an interval of 6 months. The sample consisted of 663 students, 318 male and 345 female, ages 12 to 15 years. Questionnaires were administered in a…

Longitudinal Surveys of Australian Youth (LSAY) 2009 Cohort: Wave 1 (2009)--Frequency Tables. Technical Report 70

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

The Longitudinal Surveys of Australian Youth (LSAY) program studies the progress of several groups of young Australians as they move from school into post-secondary education and work. Since 2003, the LSAY program has been integrated with the Programme for International Student Assessment (PISA) conducted by the Organisation for Economic…

Longitudinal Study of a Dual-Factor Model of Mental Health in Chinese Youth

ERIC Educational Resources Information Center

Xiong, Junmei; Qin, Yi; Gao, Miaomiao; Hai, Man

2017-01-01

By incorporating psychopathology and subjective well-being (SWB), the dual-factor model of mental health (DFM) can comprehensively measure psychological health. We examined the utility of the DFM among 1,293 Chinese adolescents (Grades 7-12). Furthermore, we examined the dynamics of mental health group membership via a two-wave longitudinal study…

HbA1c, diabetes and cognitive decline: the English Longitudinal Study of Ageing.

PubMed

Zheng, Fanfan; Yan, Li; Yang, Zhenchun; Zhong, Baoliang; Xie, Wuxiang

2018-04-01

The aim of the study was to evaluate longitudinal associations between HbA 1c levels, diabetes status and subsequent cognitive decline over a 10 year follow-up period. Data from wave 2 (2004-2005) to wave 7 (2014-2015) of the English Longitudinal Study of Ageing (ELSA) were analysed. Cognitive function was assessed at baseline (wave 2) and reassessed every 2 years at waves 3-7. Linear mixed models were used to evaluate longitudinal associations. The study comprised 5189 participants (55.1% women, mean age 65.6 ± 9.4 years) with baseline HbA 1c levels ranging from 15.9 to 126.3 mmol/mol (3.6-13.7%). The mean follow-up duration was 8.1 ± 2.8 years and the mean number of cognitive assessments was 4.9 ± 1.5. A 1 mmol/mol increment in HbA 1c was significantly associated with an increased rate of decline in global cognitive z scores (-0.0009 SD/year, 95% CI -0.0014, -0.0003), memory z scores (-0.0005 SD/year, 95% CI -0.0009, -0.0001) and executive function z scores (-0.0008 SD/year, 95% CI -0.0013, -0.0004) after adjustment for baseline age, sex, total cholesterol, HDL-cholesterol, triacylglycerol, high-sensitivity C-reactive protein, BMI, education, marital status, depressive symptoms, current smoking, alcohol consumption, hypertension, CHD, stroke, chronic lung disease and cancer. Compared with participants with normoglycaemia, the multivariable-adjusted rate of global cognitive decline associated with prediabetes and diabetes was increased by -0.012 SD/year (95% CI -0.022, -0.002) and -0.031 SD/year (95% CI -0.046, -0.015), respectively (p for trend <0.001). Similarly, memory, executive function and orientation z scores showed an increased rate of cognitive decline with diabetes. Significant longitudinal associations between HbA 1c levels, diabetes status and long-term cognitive decline were observed in this study. Future studies are required to determine the effects of maintaining optimal glucose control on the rate of cognitive decline in people with diabetes.

LONGITUDINAL TRAJECTORIES OF ARTERIAL STIFFNESS AND THE ROLE OF BLOOD PRESSURE: THE BALTIMORE LONGITUDINAL STUDY OF AGING

PubMed Central

AlGhatrif, Majd; Strait, James B.; Morrell, Chris; Canepa, Marco; Wright, Jeanette; Elango, Palchamy; Scuteri, Angelo; Najjar, Samer S.; Ferrucci, Luigi; Lakatta, Edward G.

2013-01-01

Carotid-femoral pulse wave velocity (PWV), a marker of arterial stiffness, is an established independent cardiovascular (CV) risk factor. Little information is available on the pattern and determinants of the longitudinal change in PWV with aging. Such information is crucial to elucidating mechanisms underlying arterial stiffness and the design of interventions to retard it. Between 1988 and 2013, we collected 2 to 9 serial measures of PWV in 354 men and 423 women of the Baltimore Longitudinal Study of Aging, who were 21 to 94 years of age and free of clinically significant CV disease. Rates of PWV increase accelerated with advancing age in men more than women, leading to gender differences in PWV after the age of 50. In both sexes, not only systolic blood pressure (SBP) ≥140mmHg, but also SBP of 120–139mmHg was associated with steeper rates of PWV increase compared to SBP<120mmHg. Furthermore, there was a dose-dependent effect SBP in men with marked acceleration in PWV rate of increase with age at SBP ≥140mmHg compared to SBP of 120–139mmHg. Except for waist circumference in women, no other traditional CV risk factors predicted longitudinal PWV increase. In conclusion, the steeper longitudinal increase of PWV in men than women led to gender difference that expanded with advancing age. Age and systolic blood pressure are the main longitudinal determinants of pulse wave velocity and the effect of systolic blood pressure on PWV trajectories exists even in the pre-hypertensive range. PMID:24001897

Entry into romantic partnership is associated with obesity.

PubMed

The, Natalie S; Gordon-Larsen, Penny

2009-07-01

BMI is highly correlated between spouses; however, less is understood about the underlying mechanism(s) by which the development of obesity in one individual increases the risk of obesity in his/her spouse. The objective of this study is to investigate whether romantic partnership and duration of cohabitation are related to incident obesity and obesity-promoting behaviors. We used two data sets from the National Longitudinal Study of Adolescent Health: (i) 6,949 US adolescents (wave II, 1996) followed into adulthood (wave III, 2001-2002) and (ii) 1,293 dating, cohabiting, and married romantic couples from wave III, including measured anthropometry and self-report behavior data. In the longitudinal cohort, we used sex-stratified logistic regression models to examine the risk of incident obesity by longitudinal romantic relationship status and duration of time spent living with a romantic partner. In the Couples Sample, we used multinomial logistic regression to predict concordance in outcomes: obesity, moderate-to-vigorous physical activity, and screen time by romantic partnership and duration of time living with a romantic partner. Individuals who transitioned from single/dating to cohabiting or married were more likely to become obese than those who were dating at both waves. Partner concordance for negative, obesity-related behaviors was strongest for married couples and couples who lived together > or =2 years. The shared household environment may increase the likelihood of becoming obese, influence partner concordance, and may be an important target for obesity intervention.

Panel Conditioning in the General Social Survey

ERIC Educational Resources Information Center

Halpern-Manners, Andrew; Warren, John Robert; Torche, Florencia

2017-01-01

Does participation in one wave of a survey have an effect on respondents' answers to questions in subsequent waves? In this article, we investigate the presence and magnitude of "panel conditioning" effects in one of the most frequently used data sets in the social sciences: the General Social Survey (GSS). Using longitudinal records…

The Relationship Between Early Sexual Debut and Psychosocial Outcomes: A Longitudinal Study of Dutch Adolescents

PubMed Central

Sandfort, Theo; Reitz, Ellen; Bos, Henny; Dekovic, Maja

2010-01-01

In a longitudinal dataset of 470 Dutch adolescents, the current study examined the ways in which early sexual initiation was related to subsequent attachment, self-perception, internalizing problems, and externalizing problems. For male adolescents, analyses revealed general attachment to mother and externalizing problems at Wave 1 to predict to early transition at Wave 2. However, there was no differential change in these psychosocial factors over time for early initiators of sexual intercourse and their non-initiating peers. For female adolescents, the model including psychosocial factors at Wave 1 did not predict to sexual initiation at Wave 2. However, univariate repeated measures analyses revealed early initiators to have significantly larger increases in self-concept and externalizing problems than their non-initiating female peers. While the difference between female early initiators and non-initiators were statistically significant, the mean levels of problem behaviors were very low. The findings suggest that, contrary to previous research, early sexual initiation does not seem to be clustered with problem behaviors for this sample of Dutch adolescents. PMID:20119696

Impact of Project P.A.T.H.S. on adolescent developmental outcomes in Hong Kong: findings based on seven waves of data.

PubMed

Shek, Daniel T L; Ma, Cecilia M S

2012-01-18

The present study examined the longitudinal impact of Project P.A.T.H.S. (Positive Adolescent Training through Holistic Social Programmes) on adolescent developmental outcomes in Hong Kong. Using a longitudinal randomized group design, seven waves of data were collected from 24 experimental schools (n=4049 at wave 1) in which students participated in the Tier 1 Program of Project P.A.T.H.S. and 24 control schools (n=3797 at wave 1). Results based on individual growth curve modeling generally showed that, relative to the control participants, participants in the experimental group had: (a) a higher level of positive development; (b) a lower level of substance abuse; and (c) a lower level of delinquent behavior. Participants who regarded the program to be beneficial also showed higher levels of positive development and lower levels of problem behavior than did the control school students. The present findings suggest that Project P.A.T.H.S. is effective in promoting positive development and preventing adolescent problem behavior in Chinese adolescents in Hong Kong.

Ground-based instruments of the PWING project to investigate dynamics of the inner magnetosphere at subauroral latitudes as a part of the ERG-ground coordinated observation network

NASA Astrophysics Data System (ADS)

Shiokawa, Kazuo; Katoh, Yasuo; Hamaguchi, Yoshiyuki; Yamamoto, Yuka; Adachi, Takumi; Ozaki, Mitsunori; Oyama, Shin-Ichiro; Nosé, Masahito; Nagatsuma, Tsutomu; Tanaka, Yoshimasa; Otsuka, Yuichi; Miyoshi, Yoshizumi; Kataoka, Ryuho; Takagi, Yuki; Takeshita, Yuhei; Shinbori, Atsuki; Kurita, Satoshi; Hori, Tomoaki; Nishitani, Nozomu; Shinohara, Iku; Tsuchiya, Fuminori; Obana, Yuki; Suzuki, Shin; Takahashi, Naoko; Seki, Kanako; Kadokura, Akira; Hosokawa, Keisuke; Ogawa, Yasunobu; Connors, Martin; Michael Ruohoniemi, J.; Engebretson, Mark; Turunen, Esa; Ulich, Thomas; Manninen, Jyrki; Raita, Tero; Kero, Antti; Oksanen, Arto; Back, Marko; Kauristie, Kirsti; Mattanen, Jyrki; Baishev, Dmitry; Kurkin, Vladimir; Oinats, Alexey; Pashinin, Alexander; Vasilyev, Roman; Rakhmatulin, Ravil; Bristow, William; Karjala, Marty

2017-11-01

The plasmas (electrons and ions) in the inner magnetosphere have wide energy ranges from electron volts to mega-electron volts (MeV). These plasmas rotate around the Earth longitudinally due to the gradient and curvature of the geomagnetic field and by the co-rotation motion with timescales from several tens of hours to less than 10 min. They interact with plasma waves at frequencies of mHz to kHz mainly in the equatorial plane of the magnetosphere, obtain energies up to MeV, and are lost into the ionosphere. In order to provide the global distribution and quantitative evaluation of the dynamical variation of these plasmas and waves in the inner magnetosphere, the PWING project (study of dynamical variation of particles and waves in the inner magnetosphere using ground-based network observations, http://www.isee.nagoya-u.ac.jp/dimr/PWING/) has been carried out since April 2016. This paper describes the stations and instrumentation of the PWING project. We operate all-sky airglow/aurora imagers, 64-Hz sampling induction magnetometers, 40-kHz sampling loop antennas, and 64-Hz sampling riometers at eight stations at subauroral latitudes ( 60° geomagnetic latitude) in the northern hemisphere, as well as 100-Hz sampling EMCCD cameras at three stations. These stations are distributed longitudinally in Canada, Iceland, Finland, Russia, and Alaska to obtain the longitudinal distribution of plasmas and waves in the inner magnetosphere. This PWING longitudinal network has been developed as a part of the ERG (Arase)-ground coordinated observation network. The ERG (Arase) satellite was launched on December 20, 2016, and has been in full operation since March 2017. We will combine these ground network observations with the ERG (Arase) satellite and global modeling studies. These comprehensive datasets will contribute to the investigation of dynamical variation of particles and waves in the inner magnetosphere, which is one of the most important research topics in recent space physics, and the outcome of our research will improve safe and secure use of geospace around the Earth.[Figure not available: see fulltext.

The contribution of pre- and postdisaster social support to short- and long-term mental health after Hurricanes Katrina: A longitudinal study of low-income survivors.

PubMed

Chan, Christian S; Lowe, Sarah R; Weber, Elyssa; Rhodes, Jean E

2015-08-01

A previous study of Hurricane Katrina survivors found that higher levels of predisaster social support were associated with lower psychological distress one year after the storm, and that this pathway was mediated by lower exposure to hurricane-related stressors. As a follow-up, we examined the impact of pre- and postdisaster social support on longer-term of mental health-both psychological distress and posttraumatic stress. In this three-wave longitudinal study, 492 residents in the region affected by Hurricane Katrina reported levels of perceived social support and symptoms of psychological distress prior to the storm (Wave 1). Subsequently, one year after Hurricane Katrina (Wave 2), they reported levels of exposure, perceived social support, and symptoms of psychological distress and posttraumatic stress. The latter three variables were assessed again four years after the hurricane (Wave 3). Results of mediation analysis indicated that levels of exposure to hurricane-related stressors mediated the relationship between Wave 1 perceived social support and Wave 3 psychological distress as well as postdisaster posttraumatic stress. Results of regression analyses indicated that, controlling for Wave 1 psychological distress and disaster exposure, Wave 2 perceived social support was associated with Wave 2 and Wave 3 psychological distress but not posttraumatic stress. Our results confirmed the social causation processes of social support and suggest that posttraumatic stress might not stem directly from the lack of social support. Rather, preexisting deficits in social resources might indirectly affect longer-term posttraumatic stress and general psychological distress by increasing risk for disaster-related stressors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Local time, seasonal, and solar cycle dependency of longitudinal variations of TEC along the crest of EIA over India

NASA Astrophysics Data System (ADS)

Sunda, Surendra; Vyas, B. M.

2013-10-01

global wave number 4 structure in the Indian longitudinal region spanning from ~70 to 95°E forming the upward slope of the peak in the total electron content (TEC) are reported along the crest of equatorial ionization anomaly (EIA). The continuous and simultaneous measurements from five GPS stations of GPS Aided Geo Augmented Navigation (GAGAN) network are used in this study. The long-term database (2004-2012) is utilized for examining the local time, seasonal, and solar cycle dependency on the longitudinal variations of TEC. Our results confirm the existence of longitudinal variations of TEC in accordance with wave number 4 longitudinal structure including its strength. The results suggest that these variations, in general, start to develop at ~09 LT, achieve maximum strength at 12-15 LT, and decay thereafter, the decay rate depending on the season. They are more pronounced in equinoctial season followed by summer and winter. The longitudinal variations persist beyond midnight in equinox seasons, whereas in winter, they are conspicuously absent. Interestingly, they also exhibit significant solar cycle dependence in the solstices, whereas in the equinoxes, they are independent of solar activity. The comparison of crest-to-trough ratio (CTR) in the eastern (92°E) and western (72°E) extreme longitudes reveals higher CTR on the eastern side than over the western extreme, suggesting the role of nonmigrating tides in modulating the ExB vertical drift and the consequential EIA crest formation.

Vibration Measurement on Reticular Lamina and Basilar Membrane at Multiple Longitudinal Locations

NASA Astrophysics Data System (ADS)

Chen, Fangyi; Zha, Dingjun; Choudhury, Niloy; Fridberger, Anders; Nuttall, Alfred L.

2011-11-01

The longitudinal distribution of the organ of Corti vibration is important for both understanding the energy delivery and the timing of the cochlear amplification. Recent development on low coherence interferomtry technique allows measuring vibration inside the cochlea. The reticular lamina (RL) vibration spectrum demonstrates that RL vibration leads the basilar membrane (BM). This phase lead is consistent with the idea that the active process may lead the BM vibration. In this study, measurements on multiple longitudinal locations demonstrated similar phase lead. Results on this study suggests that there may be another longitudinal coupling mechanism inside the cochlea other than the traveling wave on BM.

Theoretical basal Ca II fluxes for late-type stars: results from magnetic wave models with time-dependent ionization and multi-level radiation treatments

NASA Astrophysics Data System (ADS)

Fawzy, Diaa E.; Stȩpień, K.

2018-03-01

In the current study we present ab initio numerical computations of the generation and propagation of longitudinal waves in magnetic flux tubes embedded in the atmospheres of late-type stars. The interaction between convective turbulence and the magnetic structure is computed and the obtained longitudinal wave energy flux is used in a self-consistent manner to excite the small-scale magnetic flux tubes. In the current study we reduce the number of assumptions made in our previous studies by considering the full magnetic wave energy fluxes and spectra as well as time-dependent ionization (TDI) of hydrogen, employing multi-level Ca II atomic models, and taking into account departures from local thermodynamic equilibrium. Our models employ the recently confirmed value of the mixing-length parameter α=1.8. Regions with strong magnetic fields (magnetic filling factors of up to 50%) are also considered in the current study. The computed Ca II emission fluxes show a strong dependence on the magnetic filling factors, and the effect of time-dependent ionization (TDI) turns out to be very important in the atmospheres of late-type stars heated by acoustic and magnetic waves. The emitted Ca II fluxes with TDI included into the model are decreased by factors that range from 1.4 to 5.5 for G0V and M0V stars, respectively, compared to models that do not consider TDI. The results of our computations are compared with observations. Excellent agreement between the observed and predicted basal flux is obtained. The predicted trend of Ca II emission flux with magnetic filling factor and stellar surface temperature also agrees well with the observations but the calculated maximum fluxes for stars of different spectral types are about two times lower than observations. Though the longitudinal MHD waves considered here are important for chromosphere heating in high activity stars, additional heating mechanism(s) are apparently present.

Generation of double giant pulses in actively Q-switched lasers

NASA Astrophysics Data System (ADS)

Korobeynikova, A. P.; Shaikin, I. A.; Shaykin, A. A.; Koryukin, I. V.; Khazanov, E. A.

2018-04-01

Generation of a second giant pulse in a longitudinal mode neighbouring to the longitudinal mode possessing minimal losses is theoretically and experimentally studied in actively Q-switched lasers. A mathematical model is suggested for explaining the giant pulse generation in a laser with multiple longitudinal modes. The model makes allowance for not only a standing, but also a running wave for each cavity mode. Results of numerical simulation and data of experiments with a Nd : YLF laser explain the effect of second giant pulse generation in a neighbouring longitudinal mode. After a giant pulse in the mode with minimal losses is generated, the threshold for the neighbouring longitudinal mode is still exceeded due to the effect of burning holes in the population inversion spatial distribution.

Fluctuations in episodic and chronic migraine status over the course of 1 year: implications for diagnosis, treatment and clinical trial design.

PubMed

Serrano, Daniel; Lipton, Richard B; Scher, Ann I; Reed, Michael L; Stewart, Walter Buzz F; Adams, Aubrey Manack; Buse, Dawn C

2017-10-04

Relatively little is known about the stability of a diagnosis of episodic migraine (EM) or chronic migraine (CM) over time. This study examines natural fluctuations in self-reported headache frequency as well as the stability and variation in migraine type among individuals meeting criteria for EM and CM at baseline. The Chronic Migraine Epidemiology and Outcomes (CaMEO) Study was a longitudinal survey of US adults with EM and CM identified by a web-questionnaire. A validated questionnaire was used to classify respondents with EM (<15 headache days/month) or CM (≥15 headache days/month) every three months for a total of five assessments. We described longitudinal persistence of baseline EM and CM classifications. In addition, we modelled longitudinal variation in headache day frequency per month using negative binomial repeated measures regression models (NBRMR). Among the 5464 respondents with EM at baseline providing four or five waves of data, 5048 (92.4%) had EM in all waves and 416 (7.6%) had CM in at least one wave. Among 526 respondents with CM at baseline providing four or five waves of data, 140 (26.6%) had CM in every wave and 386 (73.4%) had EM for at least one wave. Individual plots revealed striking within-person variations in headache days per month. The NBRMR model revealed that the rate of headache days increased across waves of observation 19% more per wave for CM compared to EM (rate ratio [RR], 1.19; 95% CI, 1.13-1.26). After adjustment for covariates, the relative difference changed to a 26% increase per wave (RR, 1.26; 95% CI, 1.2-1.33). Follow-up at three-month intervals reveals a high level of short-term variability in headache days per month. As a consequence, many individuals cross the CM diagnostic boundary of ≥15 headache days per month.Nearly three quarters of persons with CM at baseline drop below this diagnostic boundary at least once over the course of a year. These findings are of interest in the consideration of headache classification and diagnosis, the design and interpretation of epidemiologic and clinical studies, and clinical management.

Laboratory study of spectral waves over a muddy bottom

NASA Astrophysics Data System (ADS)

Maxeiner, E.; Dalrymple, R. A.

2010-12-01

The attenuation of water waves propagating over a muddy ocean floor has been studied extensively both analytically and experimentally over the past 30 years. Possible mechanisms for this include surface wave interactions with the bottom, surface wave interactions with waves formed at the water/mud interface (lutocline) and shear instability at the water/mud interface. Typically these studies have focused on monochromatic waves. Observations of wave attenuation in the field, however, are subject to a spectrum of wave frequencies and sizes. A few field studies (Sheremet and Stone, 2003; Elgar and Raubenheimer, 2008) have explored the possible effects that a wide spectrum of wave frequencies may have on wave damping mechanisms. In this study, the wave attenuation exhibited by a sea spectrum over a muddy bottom is studied experimentally in a laboratory for the first time. Using an 18 m-long wave tank at the Coastal Engineering Laboratory at Johns Hopkins University, a piston-style wave maker is used to create both monochromatic and spectral waves. A 10 m-long section of the tank floor incorporates a recessed layer of kaolinite clay which subsequently mixes with the overlying water in the presence of waves. Testing consists of three phases. First, a series of monochromatic wave trains are produced over a range of wave frequencies and in a range of water depths to assess the damping behavior with respect to a variety of parameters such as wave frequency, wave height and water depth. Damping is assessed by comparing wave height at various longitudinal locations in the tank. Second, “wave beats” are created by superimposing waves of two frequencies to create a longer envelope. Third, the wave maker is used to generate a representative random sea condition, based on the Pierson-Moskowitz sea spectrum. For this type of testing, damping is assessed by measuring wave energy flux over a period of time at various longitudinal locations in the tank. Spectral analysis is also performed at these locations to track changing spectral energy, as previous studies have hypothesized mechanisms of energy transfer between waves of different frequencies. This study is part of a Multidisciplinary University Research Initiative (MURI), which includes on computational, laboratory and field studies of wave damping in nearshore areas of the Gulf of Mexico along the coast of Louisiana.

Field experiments to determine wave propagation principles and mechanical properties of snow

NASA Astrophysics Data System (ADS)

Simioni, Stephan; Gebhard, Felix; Dual, Jürg; Schweizer, Jürg

2017-04-01

To understand the release of snow avalanches by explosions one needs to know how acoustic waves travel above and within the snowpack. Hitherto, wave propagation was investigated in the laboratory with small samples or in the field in the shock wave region. We developed a measurement system and layout to derive wave attenuation in snow, wave speeds and elastic moduli on small-scale (1-2 m) field experiments to close the gap between the lab scale (0.1 m) and the scale of artificial release (10-100 m). We used solid explosives and hammer blows to create the load and accelerometers to measure the resulting wave within the snowpack. The strong attenuation we observed indicates that we measured the second longitudinal wave which propagates through the pore space. The wave speeds, however, corresponded to the speeds of the first longitudinal wave within the ice skeleton. The elastic moduli were high on the order of several tens of MPa for lower densities (150 kg m-3) and agreed well with earlier lab studies, in particular for the higher densities 250-400 kg m-3). However, the scatter was rather large as expected for in-situ experiments in the layered snow cover. In addition, we measured accelerations during propagation saw test experiments. The propagation of cracks during this type of snow instability test has mainly been studied by analysing the bending of the slab (due to the saw cut) using particle tracking velocimetry. We used the accelerometers to measure crack propagation speeds. The wave speeds were slightly higher for most experiments than reported previously. Furthermore, in some experiments, we encountered to different wave types with one propagating at a higher speed. This finding may be interpreted as the actual crack propagation and the settling of the weak layer (collapse wave). Our results show that field measurements of propagation properties are feasible and that crack propagation as observed during propagation saw tests may involve different processes that need to be further investigated.

Propagation of elastic wave in nanoporous material with distributed cylindrical nanoholes

NASA Astrophysics Data System (ADS)

Qiang, FangWei; Wei, PeiJun; Liu, XiQiang

2013-08-01

The effective propagation constants of plane longitudinal and shear waves in nanoporous material with random distributed parallel cylindrical nanoholes are studied. The surface elastic theory is used to consider the surface stress effects and to derive the nontraditional boundary condition on the surface of nanoholes. The plane wave expansion method is used to obtain the scattering waves from the single nanohole. The multiple scattering effects are taken into consideration by summing the scattered waves from all scatterers and performing the configuration averaging of random distributed scatterers. The effective propagation constants of coherent waves along with the associated dynamic effective elastic modulus are numerically evaluated. The influences of surface stress are discussed based on the numerical results.

The Longitudinal Relations among Dimensions of Parenting Styles, Sympathy, Prosocial Moral Reasoning, and Prosocial Behaviors

ERIC Educational Resources Information Center

Carlo, Gustavo; Mestre, Maria Vicenta; Samper, Paula; Tur, Ana; Armenta, Brian E.

2011-01-01

Developmental scholars assert that parents are important in fostering prosocial behaviors in adolescents, but longitudinal investigations on this topic are limited. Participants consisted of 372 boys and 358 girls with a mean age of 10.84 years (SD = 1.57) at Wave 1 from a mostly middle class community in Spain. Across three successive years,…

The Interplay of Loneliness and Depressive Symptoms across Adolescence: Exploring the Role of Personality Traits

ERIC Educational Resources Information Center

Vanhalst, Janne; Klimstra, Theo A.; Luyckx, Koen; Scholte, Ron H. J.; Engels, Rutger C. M. E.; Goossens, Luc

2012-01-01

Based on current theories of depression, reciprocal links between loneliness and depressive symptoms are expected to occur. However, longitudinal studies on adolescent samples are scarce and have yielded conflicting results. The present five-wave longitudinal study from mid- to late adolescence (N = 428, M age at T1 = 15.22 years; 47% female)…

Impact of Physical and Relational Peer Victimization on Depressive Cognitions in Children and Adolescents

ERIC Educational Resources Information Center

Sinclair, Keneisha R.; Cole, David A.; Dukewich, Tammy; Felton, Julia; Weitlauf, Amy S.; Maxwell, Melissa A.; Tilghman-Osborne, Carlos; Jacky, Amy

2012-01-01

The purpose of this study is to find longitudinal evidence of the effect of targeted peer victimization (TPV) on depressive cognitions as a function of victimization type and gender. Prospective relations of physical and relational peer victimization to positive and negative self-cognitions were examined in a 1-year, 2-wave longitudinal study.…

Does Anger Regulation Mediate the Discrimination-Mental Health Link among Mexican-Origin Adolescents? A Longitudinal Mediation Analysis Using Multilevel Modeling

ERIC Educational Resources Information Center

Park, Irene J. K.; Wang, Lijuan; Williams, David R.; Alegría, Margarita

2017-01-01

Although prior research has consistently documented the association between racial/ethnic discrimination and poor mental health outcomes, the mechanisms that underlie this link are still unclear. The present 3-wave longitudinal study tested the mediating role of anger regulation in the discrimination-mental health link among 269 Mexican-origin…

Shyness-Sensitivity and Social, School, and Psychological Adjustment in Urban Chinese Children: A Four-Wave Longitudinal Study

ERIC Educational Resources Information Center

Yang, Fan; Chen, Xinyin; Wang, Li

2015-01-01

This study examined reciprocal contributions between shyness-sensitivity and social, school, and psychological adjustment in urban Chinese children. Longitudinal data were collected once a year from Grade 3 to Grade 6 (ages 9-12 years) for 1,171 children from multiple sources. Shyness-sensitivity positively contributed to social, school, and…

Longitudinal Surveys of Australian Youth (LSAY): 1995 Cohort--User Guide. Data Elements B2: Education. Technical Report 49B2

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2009

2009-01-01

This technical paper contains information about the variables in the Longitudinal Surveys of Australian Youth (LSAY) Year 95 cohort data set. It groups each variable into data elements that identify common variables within and across waves. Information is provided about each data element, including its purpose, values, base populations and…

Longitudinal Surveys of Australian Youth (LSAY): 1995 Cohort--User Guide. Data Elements A: Demographics. Technical Report 49A

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2012

2012-01-01

This technical paper contains information about the variables in the LSAY (Longitudinal Surveys of Australian Youth) Y95 cohort data set. It groups each variable into data elements which identifies common variables within and across waves. Information is provided about each data element including its purpose, values, base populations and relevant…

Longitudinal Surveys of Australian Youth (LSAY): 1995 Cohort--User Guide. Data Elements C: Employment. Technical Report 49C

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2009

2009-01-01

This technical paper contains information about the variables in the Longitudinal Surveys of Australian Youth (LSAY) Year 95 cohort data set. It groups each variable into data elements that identify common variables within and across waves. Information is provided about each data element including its purpose, values, base populations and relevant…

Longitudinal Surveys of Australian Youth (LSAY): 1995 Cohort--User Guide. Data Elements D: Social. Technical Report 49D

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2009

2009-01-01

This technical paper contains information about the variables in the Longitudinal Surveys of Australian Youth (LSAY) Year 95 cohort data set. It groups each variable into data elements that identify common variables within and across waves. Information is provided about each data element including its purpose, values, base populations and relevant…

The Longitudinal Structure of General and Specific Anxiety Dimensions in Children: Testing a Latent Trait-State-Occasion Model

ERIC Educational Resources Information Center

Olatunji, Bunmi O.; Cole, David A.

2009-01-01

In an 8-wave, 4-year longitudinal study, 787 children (Grades 3-6) completed the Revised Children's Manifest Anxiety Scale (C. R. Reynolds & B. O. Richmond, 1985), a measure of the Physiological Reactivity, Worry-Oversensitivity, and Social Alienation dimensions of anxiety. A latent variable (trait-state-occasion) model and a latent growth curve…

Longitudinal Surveys of Australian Youth (LSAY): 1998 Cohort--User Guide. Data Elements D: Social. Technical Report 53D

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2009

2009-01-01

This technical paper contains information about the variables in the Longitudinal Surveys of Australian Youth (LSAY) Year 1998 cohort data set. It groups each variable into data elements which identifies common variables within and across waves. Information is provided about each data element including its purpose, values, base populations and…

A Longitudinal Study of the Associations between Moral Disengagement and Active Defending versus Passive Bystanding during Bullying Situations

ERIC Educational Resources Information Center

Doramajian, Caroline; Bukowski, William M.

2015-01-01

This study investigated the prospective association between moral disengagement and bystander behaviors in bullying situations, including both defending and passive bystanding. A diverse sample of Canadian school children (N = 130; 68 boys and 62 girls; mean age = 11.36 years) participated in a three-wave longitudinal study over a 4-month period.…

Children's Sympathy, Guilt, and Moral Reasoning in Helping, Cooperation, and Sharing: A 6-Year Longitudinal Study

ERIC Educational Resources Information Center

Malti, Tina; Ongley, Sophia F.; Peplak, Joanna; Chaparro, Maria P.; Buchmann, Marlis; Zuffianò, Antonio; Cui, Lixian

2016-01-01

This study examined the role of sympathy, guilt, and moral reasoning in helping, cooperation, and sharing in a 6-year, three-wave longitudinal study involving 175 children (M[subscript age] 6.10, 9.18, and 12.18 years). Primary caregivers reported on children's helping and cooperation; sharing was assessed behaviorally. Child sympathy was assessed…

Arterial wave reflection and subclinical left ventricular systolic dysfunction.

PubMed

Russo, Cesare; Jin, Zhezhen; Takei, Yasuyoshi; Hasegawa, Takuya; Koshaka, Shun; Palmieri, Vittorio; Elkind, Mitchell Sv; Homma, Shunichi; Sacco, Ralph L; Di Tullio, Marco R

2011-03-01

Increased arterial wave reflection is a predictor of cardiovascular events and has been hypothesized to be a cofactor in the pathophysiology of heart failure. Whether increased wave reflection is inversely associated with left-ventricular (LV) systolic function in individuals without heart failure is not clear. Arterial wave reflection and LV systolic function were assessed in 301 participants from the Cardiovascular Abnormalities and Brain Lesions (CABL) study using two-dimensional echocardiography and applanation tonometry of the radial artery to derive central arterial waveform by a validated transfer function. Aortic augmentation index (AIx) and wasted energy index (WEi) were used as indices of wave reflection. LV systolic function was measured by LV ejection fraction (LVEF) and tissue Doppler imaging (TDI). Mitral annulus peak systolic velocity (Sm), peak longitudinal strain and strain rate were measured. Participants with history of coronary artery disease, atrial fibrillation, LVEF less than 50% or wall motion abnormalities were excluded. Mean age of the study population was 68.3 ± 10.2 years (64.1% women, 65% hypertensive). LV systolic function by TDI was lower with increasing wave reflection, whereas LVEF was not. In multivariate analysis, TDI parameters of LV longitudinal systolic function were significantly and inversely correlated to AIx and WEi (P values from 0.05 to 0.002). In a community cohort without heart failure and with normal LVEF, an increased arterial wave reflection was associated with subclinical reduction in LV systolic function assessed by novel TDI techniques. Further studies are needed to investigate the prognostic implications of this relationship.

Chasing the reflected wave back into the heart: a new hypothesis while the jury is still out

PubMed Central

Codreanu, Ion; Robson, Matthew D; Rider, Oliver J; Pegg, Tammy J; Jung, Bernd A; Dasanu, Constantin A; Clarke, Kieran; Holloway, Cameron J

2011-01-01

Background: Arterial stiffness directly influences cardiac function and is independently associated with cardiovascular risk. However, the influence of the aortic reflected pulse pressure wave on left ventricular function has not been well characterized. The aim of this study was to obtain detailed information on regional ventricular wall motion patterns corresponding to the propagation of the reflected aortic wave on ventricular segments. Methods: Left ventricular wall motion was investigated in a group of healthy volunteers (n = 14, age 23 ± 3 years), using cardiac magnetic resonance navigator-gated tissue phase mapping. The left ventricle was divided into 16 segments and regional wall motion was studied in high temporal detail. Results: Corresponding to the expected timing of the reflected aortic wave reaching the left ventricle, a characteristic “notch” of regional myocardial motion was seen in all radial, circumferential, and longitudinal velocity graphs. This notch was particularly prominent in septal segments adjacent to the left ventricular outflow tract on radial velocity graphs and in anterior and posterior left ventricular segments on circumferential velocity graphs. Similarly, longitudinal velocity graphs demonstrated a brief deceleration in the upward recoil motion of the entire ventricle at the beginning of diastole. Conclusion: These results provide new insights into the possible influence of the reflected aortic waves on ventricular segments. Although the association with the reflected wave appears to us to be unambiguous, it represents a novel research concept, and further studies enabling the actual recording of the pulse wave are required. PMID:21731888

Data resource profile: the World Health Organization Study on global AGEing and adult health (SAGE).

PubMed

Kowal, Paul; Chatterji, Somnath; Naidoo, Nirmala; Biritwum, Richard; Fan, Wu; Lopez Ridaura, Ruy; Maximova, Tamara; Arokiasamy, Perianayagam; Phaswana-Mafuya, Nancy; Williams, Sharon; Snodgrass, J Josh; Minicuci, Nadia; D'Este, Catherine; Peltzer, Karl; Boerma, J Ties

2012-12-01

Population ageing is rapidly becoming a global issue and will have a major impact on health policies and programmes. The World Health Organization's Study on global AGEing and adult health (SAGE) aims to address the gap in reliable data and scientific knowledge on ageing and health in low- and middle-income countries. SAGE is a longitudinal study with nationally representative samples of persons aged 50+ years in China, Ghana, India, Mexico, Russia and South Africa, with a smaller sample of adults aged 18-49 years in each country for comparisons. Instruments are compatible with other large high-income country longitudinal ageing studies. Wave 1 was conducted during 2007-2010 and included a total of 34 124 respondents aged 50+ and 8340 aged 18-49. In four countries, a subsample consisting of 8160 respondents participated in Wave 1 and the 2002/04 World Health Survey (referred to as SAGE Wave 0). Wave 2 data collection will start in 2012/13, following up all Wave 1 respondents. Wave 3 is planned for 2014/15. SAGE is committed to the public release of study instruments, protocols and meta- and micro-data: access is provided upon completion of a Users Agreement available through WHO's SAGE website (www.who.int/healthinfo/systems/sage) and WHO's archive using the National Data Archive application (http://apps.who.int/healthinfo/systems/surveydata).

Data Resource Profile: The World Health Organization Study on global AGEing and adult health (SAGE)

PubMed Central

Kowal, Paul; Chatterji, Somnath; Naidoo, Nirmala; Biritwum, Richard; Fan, Wu; Lopez Ridaura, Ruy; Maximova, Tamara; Arokiasamy, Perianayagam; Phaswana-Mafuya, Nancy; Williams, Sharon; Snodgrass, J Josh; Minicuci, Nadia; D'Este, Catherine; Peltzer, Karl; Boerma, J Ties; Yawson, A.; Mensah, G.; Yong, J.; Guo, Y.; Zheng, Y.; Parasuraman, P.; Lhungdim, H.; Sekher, TV.; Rosa, R.; Belov, VB.; Lushkina, NP; Peltzer, K.; Makiwane, M.; Zuma, K.; Ramlagan, S.; Davids, A.; Mbelle, N.; Matseke, G.; Schneider, M.; Tabane, C.; Tollman, S.; Kahn, K.; Ng, N.; Juvekar, S.; Sankoh, O.; Debpuur, CY.; Nguyen, TK Chuc; Gomez-Olive, FX.; Hakimi, M.; Hirve, S.; Abdullah, S.; Hodgson, A.; Kyobutungi, C.; Egondi, T.; Mayombana, C.; Minh, HV.; Mwanyangala, MA.; Razzaque, A.; Wilopo, S.; Streatfield, PK.; Byass, P.; Wall, S.; Scholten, F.; Mugisha, J.; Seeley, J.; Kinyanda, E.; Nyirenda, M.; Mutevedzi, P.; Newell, M-L.

2012-01-01

Population ageing is rapidly becoming a global issue and will have a major impact on health policies and programmes. The World Health Organization’s Study on global AGEing and adult health (SAGE) aims to address the gap in reliable data and scientific knowledge on ageing and health in low- and middle-income countries. SAGE is a longitudinal study with nationally representative samples of persons aged 50+ years in China, Ghana, India, Mexico, Russia and South Africa, with a smaller sample of adults aged 18–49 years in each country for comparisons. Instruments are compatible with other large high-income country longitudinal ageing studies. Wave 1 was conducted during 2007–2010 and included a total of 34 124 respondents aged 50+ and 8340 aged 18–49. In four countries, a subsample consisting of 8160 respondents participated in Wave 1 and the 2002/04 World Health Survey (referred to as SAGE Wave 0). Wave 2 data collection will start in 2012/13, following up all Wave 1 respondents. Wave 3 is planned for 2014/15. SAGE is committed to the public release of study instruments, protocols and meta- and micro-data: access is provided upon completion of a Users Agreement available through WHO’s SAGE website (www.who.int/healthinfo/systems/sage) and WHO’s archive using the National Data Archive application (http://apps.who.int/healthinfo/systems/surveydata). PMID:23283715

Imaging mechanical properties of hepatic tissue by magnetic resonance elastography

NASA Astrophysics Data System (ADS)

Yin, Meng; Rouviere, Olivier; Burgart, Lawrence J.; Fidler, Jeff L.; Manduca, Armando; Ehman, Richard L.

2006-03-01

PURPOSE: To assess the feasibility of a modified phase-contrast MRI technique (MR Elastography) for quantitatively assessing the mechanical properties of hepatic tissues by imaging propagating acoustic shear waves. MATERIALS AND METHODS: Both phantom and human studies were performed to develop and optimize a practical imaging protocol by visualizing and investigating the diffraction field of shear waves generated from pneumatic longitudinal drivers. The effects of interposed ribs in a transcostal approach were also investigated. A gradient echo MRE pulse sequence was adapted for shear wave imaging in the liver during suspended respiration, and then tested to measure hepatic shear stiffness in 13 healthy volunteers and 1 patient with chronic liver disease to determine the potential of non-invasively detecting liver fibrosis. RESULTS: Phantom studies demonstrate that longitudinal waves generated by the driver are mode-converted to shear waves in a distribution governed by diffraction principles. The transcostal approach was determined to be the most effective method for generating shear waves in human studies. Hepatic stiffness measurements in the 13 normal volunteers demonstrated a mean value of 2.0+/-0.2kPa. The shear stiffness measurement in the patient was much higher at 8.5kPa. CONCLUSION: MR Elastography of the liver shows promise as a method to non-invasively detect and characterize diffuse liver disease, potentially reducing the need for biopsy to diagnose hepatic fibrosis.

Piezoelectric shear wave resonator and method of making same

DOEpatents

Wang, J.S.; Lakin, K.M.; Landin, A.R.

1985-05-20

An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppM//sup 0/C.

Piezoelectric shear wave resonator and method of making same

DOEpatents

Wang, J.S.; Lakin, K.M.; Landin, A.R.

1983-10-25

An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppM//sup 0/C.

Large magnetic to electric field contrast in azimuthally polarized vortex beams generated by a metasurface (Presentation Recording)

NASA Astrophysics Data System (ADS)

Veysi, Mehdi; Guclu, Caner; Capolino, Filippo

2015-09-01

We investigate azimuthally E-polarized vortex beams with enhanced longitudinal magnetic field. Ideally, such beams possess strong longitudinal magnetic field on the beam axis where there is no electric field. First we formulate the electric field vector and the longitudinal magnetic field of an azimuthally E-polarized beam as an interference of right- and left-hand circularly polarized Laguerre Gaussian (LG) beams carrying the orbital angular momentum (OAM) states of -1 and +1, respectively. Then we propose a metasurface design that is capable of converting a linearly polarized Gaussian beam into an azimuthally E-polarized vortex beam with longitudinal magnetic field. The metasurface is composed of a rectangular array of double-layer double split-ring slot elements, though other geometries could be adopted as well. The element is specifically designed to have nearly a 180° transmission phase difference between the two polarization components along two orthogonal axes, similar to the optical axes of a half-wave plate. By locally rotating the optical axes of each metasurface element, the transmission phase profile of the circularly polarized waves over the metasurface can be tailored. Upon focusing of the generated vortex beam through a lens with a numerical aperture of 0.7, a 41-fold enhancement of the magnetic to electric field ratio is achieved on the beam axis with respect to that of a plane wave. Generation of beams with large magnetic field to electric field contrast can find applications in future spectroscopy systems based on magnetic dipole transitions, which are usually much weaker than electric dipole transitions.

Are neurocognitive speed and inconsistency similarly affected in type 2 diabetes?

PubMed

Whitehead, Bonnie P; Dixon, Roger A; Hultsch, David F; MacDonald, Stuart W S

2011-07-01

Type 2 diabetes (T2D) is a disease of aging with indirect but detectable and cumulative neurological implications. We systematically tested whether neurocognitive speed (mean rate) or inconsistency (intraindividual variability) was the more sensitive clinical marker of T2D. Three of four research questions used a cross-sectional wave of the Victoria Longitudinal Study (VLS) divided into T2D (age 55-81 years) and control (age = 53-91 years) groups. The fourth question addressed relative two-wave longitudinal changes. Each of four speeded tasks produced intraindividual mean rate (IM) and intraindividual standard deviation (ISD) scores. First, the T2D group performed more slowly than the controls. Second, this deficit extended to inconsistency, but less uniformly. Third, based on logistic regression analyses, IM was the more effective predictor of T2D status. Fourth, we observed similar longitudinal change patterns for IM and ISD. Results are linked to the theoretical location of T2D on an adjusted neural vulnerability continuum.

Are Neurocognitive Speed and Inconsistency Similarly Affected in Type 2 Diabetes?

PubMed Central

Whitehead, Bonnie P.; Dixon, Roger A.; Hultsch, David F.; MacDonald, Stuart W.S.

2011-01-01

Type 2 diabetes (T2D) is a disease of aging with indirect but detectable and cumulative neurological implications. We systematically tested whether neurocognitive speed (mean rate) or inconsistency (intraindividual variability) was the more sensitive clinical marker of T2D. Three of four research questions used a cross-sectional wave of the Victoria Longitudinal Study (VLS) divided into T2D (age 55-81 years) and control (age = 53-91 years) groups. The fourth question addressed relative two-wave longitudinal changes. Each of four speeded tasks produced intraindividual mean rate (IM) and intraindividual standard deviation (ISD) scores. First, the T2D group performed more slowly than the controls. Second, this deficit extended to inconsistency, but less uniformly. Third, based on logistic regression analyses, IM was the more effective predictor of T2D status. Fourth, we observed similar longitudinal change patterns for IM and ISD. Results are linked to the theoretical location of T2D on an adjusted neural vulnerability continuum. PMID:21416426

Application of an Extended Parabolic Equation to the Calculation of the Mean Field and the Transverse and Longitudinal Mutual Coherence Functions Within Atmospheric Turbulence

NASA Technical Reports Server (NTRS)

Manning, Robert M.

2005-01-01

Solutions are derived for the generalized mutual coherence function (MCF), i.e., the second order moment, of a random wave field propagating through a random medium within the context of the extended parabolic equation. Here, "generalized" connotes the consideration of both the transverse as well as the longitudinal second order moments (with respect to the direction of propagation). Such solutions will afford a comparison between the results of the parabolic equation within the pararaxial approximation and those of the wide-angle extended theory. To this end, a statistical operator method is developed which gives a general equation for an arbitrary spatial statistical moment of the wave field. The generality of the operator method allows one to obtain an expression for the second order field moment in the direction longitudinal to the direction of propagation. Analytical solutions to these equations are derived for the Kolmogorov and Tatarskii spectra of atmospheric permittivity fluctuations within the Markov approximation.

Effects of nanosilver on sound absorption coefficients in solid wood species.

PubMed

Taghiyari, Hamid Reza; Esmailpour, Ayoub; Zolfaghari, Habib

2016-06-01

Sound absorption coefficients (ACs) were determined in five solid woods (poplar, beech, walnut, mulberry, and fir) in the longitudinal and tangential directions at four different frequencies of 800, 1000, 2000, and 4000 Hz. The length of the longitudinal and tangential specimens was 50-mm and 10-mm, respectively. Separate sets of specimens were impregnated with either nanosilver suspension or water. The size range of nanoparticles was 30-80 nm. Results showed that sound ACs were lower in longitudinal specimens because sound waves could penetrate the open ends of vessels more easily, being trapped and damped there. Impregnation with both nanosilver suspension and water resulted in a significant decrease in the sound ACs. The decrease in the ACs was due to the collapsing and accumulation of perforation plates and cell parts, blocking the way through which waves could pass through the vessels. This caused higher damping due to a phenomenon called vibration decay. Correlation between gas permeability versus sound AC is significantly dependant on the porous structure of individual specimens.

The MJO-SSW Teleconnection: Interaction Between MJO-Forced Waves and the Midlatitude Jet

NASA Astrophysics Data System (ADS)

Kang, Wanying; Tziperman, Eli

2018-05-01

The Madden-Julian Oscillation (MJO) was shown to affect both present-day sudden stratospheric warming (SSW) events in the Arctic and their future frequency under global warming scenarios, with implications to the Arctic Oscillation and midlatitude extreme weather. This work uses a dry dynamic core model to understand the dependence of SSW frequency on the amplitude and longitudinal range of the MJO, motivated by the prediction that the MJO will strengthen and broaden its longitudinal range in a warmer climate. We focus on the response of the midlatitude jets and the corresponding generated stationary waves, which are shown to dominate the response of SSW events to MJO forcing. Momentum budget analysis of a large ensemble of spinup simulations suggests that the climatological jet response is driven by the MJO-forced meridional eddy momentum transport. The results suggest that the trends in both MJO amplitude and longitudinal range are important for the prediction of the midlatitude jet response and for the prediction of SSWs in a future climate.

Extending the Trait-State-Occasion Model: How Important Is Within-Wave Measurement Equivalence?

ERIC Educational Resources Information Center

Ciesla, Jeffrey A.; Cole, David A.; Steiger, James H.

2007-01-01

Trait-State-Occasion (TSO) covariance models represent an important advance in methods for studying the longitudinal stability of latent constructs. Such models have only been examined under fairly restricted conditions (e.g., having only 2 tau-equivalent indicators per wave). In this study, Monte Carlo simulations revealed the effects of having 2…

Demonstrating Sound Wave Propagation with Candle Flame and Loudspeaker

ERIC Educational Resources Information Center

Hrepic, Zdeslav; Nettles, Corey; Bonilla, Chelsea

2013-01-01

The motion of a candle flame in front of a loudspeaker has been suggested as a productive demonstration of the longitudinal wave nature of sound. The demonstration has been used also as a research tool to investigate students' understanding about sound. The underpinning of both applications is the expectation of a horizontal, back-and-forth…

Self-Esteem, Depressive Symptoms, and Adolescents' Sexual Onset

ERIC Educational Resources Information Center

Longmore, Monica A.; Manning, Wendy D.; Giordano, Peggy C.; Rudolph, Jennifer L.

2004-01-01

We examine whether self-esteem and depressive symptoms influence sexual onset when important controls such as age, dating, race, and income are examined. Analyses are based on the first two waves of the restricted-use sample of the National Longitudinal Study of Adolescent Health. We examine adolescents who reported at wave 1 that they had not had…

Authoritarian Parenting and Asian Adolescent School Performance: Insights from the US and Taiwan

ERIC Educational Resources Information Center

Pong, Suet-ling; Johnston, Jamie; Chen, Vivien

2010-01-01

Our study re-examines the relationship between parenting and school performance among Asian students. We use two sources of data: wave I of the Adolescent Health Longitudinal Survey (Add Health), and waves I and II of the Taiwan Educational Panel Survey (TEPS). Analysis using Add Health reveals that the Asian-American/European-American difference…

Longitudinal Genetic Analysis of Early Reading: The Western Reserve Reading Project

ERIC Educational Resources Information Center

Petrill, Stephen A.; Deater-Deckard, Kirby; Thompson, Lee Anne; Schatschneider, Chris; DeThorne, Laura S.; Vandenbergh, David J.

2007-01-01

We examined the genetic and environmental contribution to the stability and instability of reading outcomes in early elementary school using a sample of 283 twin pairs drawn from the Western Reserve Reading Project. Twins were assessed across two measurement occasions. In Wave 1, children were either in kindergarten or first grade. Wave 2…

Use of acousto-ultrasonic techniques to determine properties of remanufactured particleboards made solely from recycled particles

Treesearch

Sumire Kawamoto; James H. Muehl; R. Sam Williams

2005-01-01

Properties of particleboard manufactured entirely from recycled particleboard were tested The method for processing three-layer particleboard from all-recycled particles was described. Dynamic MOE (modulus of elasticity) before and after re-manufacturing was tested by a longitudinal stress wave technique. Some stress wave techniques were compared. Nondestructive AU (...

Reciprocal Associations between Connectedness and Autonomy among Korean Adolescents: Compatible or Antithetical?

ERIC Educational Resources Information Center

Yu, Jeong Jin

2011-01-01

The primary goal of this study was to examine the longitudinal reciprocal relationships between connectedness to parents and autonomy among Korean adolescents using five annual waves of the Korea Youth Panel Survey. The sample consisted of 3,449 adolescents, whose mean age was 13.79 years at Wave 1. Contrary to the mainstream findings in…

Cohort profile: the Motorik-Modul Longitudinal Study: physical fitness and physical activity as determinants of health development in German children and adolescents.

PubMed

Wagner, Matthias O; Bös, Klaus; Jekauc, Darko; Karger, Claudia; Mewes, Nadine; Oberger, Jennifer; Reimers, Anne K; Schlenker, Lars; Worth, Annette; Woll, Alexander

2014-10-01

The Motorik-Modul (MoMo) Longitudinal Study aims to contribute to long-term improvement in the health of German children and adolescents by focusing on: (i) the development of physical fitness and physical activity (including period effects); (ii) the individual and physical/social environmental determinants of the development of physical fitness and physical activity; and (iii) the impact of physical fitness and physical activity on the development of physical and mental health. The MoMo Longitudinal Study began with a nationwide representative sample of 4529 children and adolescents who ranged in age from 4-17 years at the study baseline (2003-2006). The first survey wave of the MoMo Longitudinal Study was conducted between 2009 and 2012, with two subsequent survey waves to be conducted between 2014 and 2016 and 2018 and 2020, respectively. The MoMo Longitudinal Study includes a physical fitness test profile, a physical activity questionnaire, and subjective and objective measures of health from the German Health Interview and Examination Survey (KiGGS). Data access is provided on request (alexander.woll@kit.edu). For further information, including a complete list of publications please visit www.motorik-modul.de. Published by Oxford University Press on behalf of the International Epidemiological Association © The Author 2013; all rights reserved.

Patterns of productive activity engagement as a longitudinal predictor of depressive symptoms among older adults in urban China.

PubMed

Liu, Huiying; Lou, Vivian W Q

2017-11-01

Using two waves of panel data from the China Health and Retirement Longitudinal Study, this study prospectively assessed whether four distinct patterns of productive activity engagement would predict depressive symptoms among older adults in urban China two years later. A sample of urban residents aged 60 or above at Wave 1 and who were interviewed in both waves (N = 2398) was used. Latent class analysis (LCA) was conducted to identify distinct patterns of productive activity engagement that occurred within the Wave 1 data. Next, the generalized estimating equations were used to assess whether identified patterns predicted the levels of depressive symptoms measured at Wave 2. Our use of LCA confirmed the existence of four distinct patterns of productive activity engagement among the study sample: Informal Helper/Carer, Working-Caring Engager, Civic Contributor, and Low/Spousal Carer. All of these three patterns exhibited significantly lower levels of depressive symptoms than that of Low/Spousal Carer two years later. Our use of individual-based categorization of productive engagement better captured the reality of older adults performing various productive activities than summative scales of productive activities did and, therefore, provided a more valid clarification of differential well-being outcomes among older adults.

Interplay of normative beliefs and behavior in developmental patterns of physical and relational aggression in adolescence: a four-wave longitudinal study

PubMed Central

Krahé, Barbara; Busching, Robert

2014-01-01

In a longitudinal study with N = 1,854 adolescents from Germany, we investigated patterns of change and gender differences in physical and relational aggression in relation to normative beliefs about these two forms of aggression. Participants, whose mean age was 13 years at T1, completed self-report measures of physically and relationally aggressive behavior and indicated their normative approval of both forms of aggression at four data waves separated by 12-month intervals. Boys scored higher than did girls on both forms of aggression, but the gender difference was more pronounced for physical aggression. Physical aggression decreased and relational aggression increased over the four data waves in both gender groups. The normative acceptance of both forms of aggression decreased over time, with a greater decrease for the approval of physical aggression. In both gender groups, normative approval of relational aggression prospectively predicted relational aggression across all data waves, and the normative approval of physical aggression predicted physically aggressive behavior at the second and third data waves. A reciprocal reinforcement of aggressive norms and behavior was found for both forms of aggression. The findings are discussed as supporting a social information processing perspective on developmental patterns of change in physical and relational aggression in adolescence. PMID:25360124

Interplay of normative beliefs and behavior in developmental patterns of physical and relational aggression in adolescence: a four-wave longitudinal study.

PubMed

Krahé, Barbara; Busching, Robert

2014-01-01

In a longitudinal study with N = 1,854 adolescents from Germany, we investigated patterns of change and gender differences in physical and relational aggression in relation to normative beliefs about these two forms of aggression. Participants, whose mean age was 13 years at T1, completed self-report measures of physically and relationally aggressive behavior and indicated their normative approval of both forms of aggression at four data waves separated by 12-month intervals. Boys scored higher than did girls on both forms of aggression, but the gender difference was more pronounced for physical aggression. Physical aggression decreased and relational aggression increased over the four data waves in both gender groups. The normative acceptance of both forms of aggression decreased over time, with a greater decrease for the approval of physical aggression. In both gender groups, normative approval of relational aggression prospectively predicted relational aggression across all data waves, and the normative approval of physical aggression predicted physically aggressive behavior at the second and third data waves. A reciprocal reinforcement of aggressive norms and behavior was found for both forms of aggression. The findings are discussed as supporting a social information processing perspective on developmental patterns of change in physical and relational aggression in adolescence.

Near-planar TS waves and longitudinal vortices in channel flow: Nonlinear interaction and focusing

NASA Technical Reports Server (NTRS)

Hall, P.; Smith, F. T.

1989-01-01

The nonlinear interaction between planar or near-planar Tollmien-Schlichting waves and longitudinal vortices, induced or input, is considered theoretically for channel flows at high Reynolds numbers. Several kinds of nonlinear interaction, dependent on the input amplitudes and wavenumbers or on previously occurring interactions, are found and inter-related. The first, Type 1, is studied the most here and it usually produces spanwise focusing of both the wave and the vortex motion, within a finite scaled time, along with enhancement of both their amplitudes. This then points to the nonlinear interaction Type 2 where new interactive effects come into force to drive the wave and the vortex nonlinearly. Types 3, 4 correspond to still higher amplitudes, with 3 being related to 2, while 4 is connected with a larger-scale interaction 5 studied in an allied paper. Both 3, 4 are subsets of the full three-dimensional triple-deck-lie interaction, 6. The strongest nonlinear interactions are those of 4, 5, 6 since they alter the mean-flow profile substantially, i.e., by an 0(1) relative amount. All the types of nonlinear interaction however can result in the formation of focussed responses in the sense of spanwise concentrations and/or amplifications of vorticity and wave amplitude.

Bending, longitudinal and torsional wave transmission on Euler-Bernoulli and Timoshenko beams with high propagation losses.

PubMed

Wang, X; Hopkins, C

2016-10-01

Advanced Statistical Energy Analysis (ASEA) is used to predict vibration transmission across coupled beams which support multiple wave types up to high frequencies where Timoshenko theory is valid. Bending-longitudinal and bending-torsional models are considered for an L-junction and rectangular beam frame. Comparisons are made with measurements, Finite Element Methods (FEM) and Statistical Energy Analysis (SEA). When beams support at least two local modes for each wave type in a frequency band and the modal overlap factor is at least 0.1, measurements and FEM have relatively smooth curves. Agreement between measurements, FEM, and ASEA demonstrates that ASEA is able to predict high propagation losses which are not accounted for with SEA. These propagation losses tend to become more important at high frequencies with relatively high internal loss factors and can occur when there is more than one wave type. At such high frequencies, Timoshenko theory, rather than Euler-Bernoulli theory, is often required. Timoshenko theory is incorporated in ASEA and SEA using wave theory transmission coefficients derived assuming Euler-Bernoulli theory, but using Timoshenko group velocity when calculating coupling loss factors. The changeover between theories is appropriate above the frequency where there is a 26% difference between Euler-Bernoulli and Timoshenko group velocities.

Change in organizational justice as a predictor of insomnia symptoms: longitudinal study analysing observational data as a non-randomized pseudo-trial.

PubMed

Lallukka, Tea; Halonen, Jaana I; Sivertsen, Børge; Pentti, Jaana; Stenholm, Sari; Virtanen, Marianna; Salo, Paula; Oksanen, Tuula; Elovainio, Marko; Vahtera, Jussi; Kivimäki, Mika

2017-08-01

Despite injustice at the workplace being a potential source of sleep problems, longitudinal evidence remains scarce. We examined whether changes in perceived organizational justice predicted changes in insomnia symptoms. Data on 24 287 Finnish public sector employees (82% women), from three consecutive survey waves between 2000 and 2012, were treated as 'pseudo-trials'. Thus, the analysis of unfavourable changes in organizational justice included participants without insomnia symptoms in Waves 1 and 2, with high organizational justice in Wave 1 and high or low justice in Wave 2 (N = 6307). In the analyses of favourable changes in justice, participants had insomnia symptoms in Waves 1 and 2, low justice in Wave 1 and high or low justice in Wave 2 (N = 2903). In both analyses, the outcome was insomnia symptoms in Wave 3. We used generalized estimating equation models to analyse the data. After adjusting for social and health-related covariates in Wave 1, unfavourable changes in relational organizational justice (i.e. fairness of managerial behaviours) were associated with increased odds of developing insomnia symptoms [odds ratio = 1.15; 95% confidence interval (CI) 1.02-1.30]. A favourable change in relational organizational justice was associated with lower odds of persistent insomnia symptoms (odds ratio = 0.83; 95% CI 0.71-0.96). Changes in procedural justice (i.e. the fairness of decision-making procedures) were not associated with insomnia symptoms. These data suggest that changes in perceived relational justice may affect employees' sleep quality. Decreases in the fairness of managerial behaviours were linked to increases in insomnia symptoms, whereas rises in fairness were associated with reduced insomnia symptoms. © The Author 2017. Published by Oxford University Press on behalf of the International Epidemiological Association.

Change in organizational justice as a predictor of insomnia symptoms: longitudinal study analysing observational data as a non-randomized pseudo-trial

PubMed Central

Lallukka, Tea; Halonen, Jaana I; Sivertsen, Børge; Pentti, Jaana; Stenholm, Sari; Virtanen, Marianna; Salo, Paula; Oksanen, Tuula; Elovainio, Marko; Vahtera, Jussi; Kivimäki, Mika

2017-01-01

Abstract Background Despite injustice at the workplace being a potential source of sleep problems, longitudinal evidence remains scarce. We examined whether changes in perceived organizational justice predicted changes in insomnia symptoms. Methods Data on 24 287 Finnish public sector employees (82% women), from three consecutive survey waves between 2000 and 2012, were treated as ‘pseudo-trials’. Thus, the analysis of unfavourable changes in organizational justice included participants without insomnia symptoms in Waves 1 and 2, with high organizational justice in Wave 1 and high or low justice in Wave 2 (N = 6307). In the analyses of favourable changes in justice, participants had insomnia symptoms in Waves 1 and 2, low justice in Wave 1 and high or low justice in Wave 2 (N = 2903). In both analyses, the outcome was insomnia symptoms in Wave 3. We used generalized estimating equation models to analyse the data. Results After adjusting for social and health-related covariates in Wave 1, unfavourable changes in relational organizational justice (i.e. fairness of managerial behaviours) were associated with increased odds of developing insomnia symptoms [odds ratio = 1.15; 95% confidence interval (CI) 1.02-1.30]. A favourable change in relational organizational justice was associated with lower odds of persistent insomnia symptoms (odds ratio = 0.83; 95% CI 0.71-0.96). Changes in procedural justice (i.e. the fairness of decision-making procedures) were not associated with insomnia symptoms. Conclusions These data suggest that changes in perceived relational justice may affect employees’ sleep quality. Decreases in the fairness of managerial behaviours were linked to increases in insomnia symptoms, whereas rises in fairness were associated with reduced insomnia symptoms. PMID:28065888

An ultrasonic technique for measuring stress in fasteners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stevens, K. J.; Day, P.; Byron, D.

1999-12-02

High temperature bolting alloys are extensively used in the thermal power generation industry as for example, reheat ESV and Governor valve studs. Remnant life assessment methodologies and plant maintenance procedures require the monitoring of the operational stress levels in these fasteners. Some conventional ultrasonic techniques require longitudinal wave measurements to be undertaken when the nut on the bolt is loosened and then re-tightened. Other techniques use a combination of shear waves and longitudinal waves. In this paper, the problems and pitfalls associated with various ultrasonic techniques for measuring stress in bolts, is discussed. An ultrasonic technique developed for measuring themore » stress in Durehete 1055 bolts is presented. Material from a textured rolled bar has been used as a test bed in the development work. The technique uses shear wave birefringence and compression waves at several frequencies to measure texture, fastener length and the average stress. The technique was developed by making ultrasonic measurements on bolts tensioned in universal testing machines and a hydraulic nut. The ultrasonic measurements of residual stress have been checked against strain gauge measurements. The Durehete bolts have a hollow cylinder geometry of restricted dimensions, which significantly alters compression and shear wave velocities from bulk values and introduces hoop stresses which can be measured by rotating the polarization of the shear wave probe. Modelling of the experimental results has been undertaken using theories for the elastic wave propagation through waveguides. The dispersion equations allow the velocity and length of the fastener to be measured ultrasonically in some situations where the length of the fastener can not be measured directly with a vernier caliper or micrometer and/or where it is undesirable to loosen nuts to take calibration readings of the shear and compression wave velocities.« less

Ultrasonic bulk wave measurements on composite using fiber from recycled CFRP

NASA Astrophysics Data System (ADS)

Paterson, David; Ijomah, Winifred L.; Windmill, James F. C.; Kao, Chih-Chuan; Smillie, Grant

2018-04-01

This study investigates the velocity profile for both a virgin carbon fiber reinforced plastic (v-CFRP) and a reused fiber CFRP (rf-CFRP) which exhibit quasi-isotropy; all samples have 3 iterations of symmetry type [0, -45, +45, 90]s. An isotropic virgin CFRP (v-CFRP), produced by using a hand layup process, is presented along with a pyrolysis recycling process (at 600°C) designed to extract the carbon fibers. A virgin carbon fiber mat with a similar architecture was also thermally conditioned under the same pyrolysis conditions. Both resultant carbon fiber mats were used to produce the rf-CFRPs. Ultrasonic wave velocities at different angles of incidence for both v-CFRP and rf-CFRP were recorded. In the case of v-CFRP, two samples were studied, and it was recorded that the velocity for both a longitudinal wave and transverse wave remained relatively constant up until these waves completely attenuated at observed angles, indicating what would be expected from an isotropic sample. A close relationship in terms of waves speed was also recorded for the two v-CFRP samples. In the case of rf-CFRP, the longitudinal wave velocities were generally less closely related when compared to the v-CFRP, with a maximum of approximately 32% difference being recorded. The transverse wave velocity was also found to decrease incident angle indicating sample anisotropy. The authors suggest that the more severe decreasing velocity with increasing incident angle, when compared to v-CFRP, may be caused by resin impregnation issues and not by changes that occur during the recycling process. Therefore, a hypothesis that both the rf-CFRP and the V-CFRP will return a similar wave profile given an identical resin fiber content is put forward.

The association of BMI and externally-perceived attractiveness across race/ethnicity, gender, and time

PubMed Central

Richmond, Tracy K.; Austin, S. Bryn; Walls, Courtney E.; Subramanian, S.V.

2011-01-01

Purpose Being perceived by others as unattractive is associated with negative health and social consequences. Overweight persons may be more likely to be perceived by others as unattractive further endangering their well-being. Our objective was to determine if BMI was associated with perceptions by others of attractiveness and if this relationship was similar across race/ethnicity, gender, and time. Methods We analyzed Waves I and III of the National Longitudinal Study of Adolescent Health, a nationally representative longitudinal study of adolescents. We used participant gender- and race/ethnicity-stratified multinomial logistic regression to examine the association between BMI and interviewer-rated attractiveness (1=Unattractive, 2=Average, 3=Attractive, 4=Very Attractive) controlling for participant age, household income, and maternal education. Results BMI was positively associated with risk of being categorized as Unattractive (relative to Very Attractive) by the interviewer in Black (Wave I relative risk ratio [RRR]=1.26, CI: 1.18, 1.33; Wave III RRR=1.14, CI: 1.08, 1.20), Hispanic (Wave I RRR=1.23, CI: 1.11, 1.36; Wave III RRR=1.22, CI: 1.12, 1.34), and White (Wave I RRR=1.25, CI: 1.19, 1.32; Wave III RRR= 1.22, CI:1.17, 1.28) females in both Waves of data collection. Only in African-American females did the risk of being rated Unattractive with increasing BMI decline significantly between Waves (p=0.00018). Trends were similar in males though the magnitude of risk was smaller and non-significant in most groups. Conclusions Interviewers were more likely to rate those with higher BMIs unattractive; this finding was similar across gender and racial/ethnic groups with few exceptions and was stable across time. PMID:22188837

On Hokusai's Great wave off Kanagawa: localization, linearity and a rogue wave in sub-Antarctic waters.

PubMed

Dudley, J M; Sarano, V; Dias, F

2013-06-20

The Hokusai woodcut entitled The great wave off Kanagawa has been interpreted as an unusually large storm wave, likely to be classed as a rogue wave, and possibly generated from nonlinear wave dynamics (J. H. E. Cartwright and H. Nakamura, Notes Rec. R. Soc. 63 , 119-135 (2009)). In this paper, we present a complementary discussion of this hypothesis, discussing in particular how linear and nonlinear mechanisms can both contribute to the emergence of rogue wave events. By making reference to the Great wave 's simultaneous transverse and longitudinal localization, we show that the purely linear mechanism of directional focusing also predicts characteristics consistent with those of the Great wave . In addition, we discuss the properties of a particular rogue wave photographed on the open ocean in sub-Antarctic waters, which shows two-dimensional localization and breaking dynamics remarkably similar to Hokusai's depiction in the woodcut.

On Hokusai's Great wave off Kanagawa: localization, linearity and a rogue wave in sub-Antarctic waters

PubMed Central

Dudley, J. M.; Sarano, V.; Dias, F.

2013-01-01

The Hokusai woodcut entitled The great wave off Kanagawa has been interpreted as an unusually large storm wave, likely to be classed as a rogue wave, and possibly generated from nonlinear wave dynamics (J. H. E. Cartwright and H. Nakamura, Notes Rec. R. Soc. 63, 119–135 (2009)). In this paper, we present a complementary discussion of this hypothesis, discussing in particular how linear and nonlinear mechanisms can both contribute to the emergence of rogue wave events. By making reference to the Great wave's simultaneous transverse and longitudinal localization, we show that the purely linear mechanism of directional focusing also predicts characteristics consistent with those of the Great wave. In addition, we discuss the properties of a particular rogue wave photographed on the open ocean in sub-Antarctic waters, which shows two-dimensional localization and breaking dynamics remarkably similar to Hokusai's depiction in the woodcut. PMID:24687148

Seismic shear waves as Foucault pendulum

NASA Astrophysics Data System (ADS)

Snieder, Roel; Sens-Schönfelder, Christoph; Ruigrok, Elmer; Shiomi, Katsuhiko

2016-03-01

Earth's rotation causes splitting of normal modes. Wave fronts and rays are, however, not affected by Earth's rotation, as we show theoretically and with observations made with USArray. We derive that the Coriolis force causes a small transverse component for P waves and a small longitudinal component for S waves. More importantly, Earth's rotation leads to a slow rotation of the transverse polarization of S waves; during the propagation of S waves the particle motion behaves just like a Foucault pendulum. The polarization plane of shear waves counteracts Earth's rotation and rotates clockwise in the Northern Hemisphere. The rotation rate is independent of the wave frequency and is purely geometric, like the Berry phase. Using the polarization of ScS and ScS2 waves, we show that the Foucault-like rotation of the S wave polarization can be observed. This can affect the determination of source mechanisms and the interpretation of observed SKS splitting.

Crash injury risk behavior in adolescent latino males: the power of friends and relational connections.

PubMed

Vaca, Federico E; Anderson, Craig L

2011-01-01

The adolescent Latino male mortality profile is an anomaly when compared to an otherwise more favorable overall U.S. Latino population mortality profile. Motor vehicle crash fatalities bear a considerable proportion of mortality burden in this vulnerable population. Friend influence and relational connection are two contextual domains that may mediate crash injury risk behavior in these adolescents. Our study goal was to assess the role of friend influence over time and relational connections associated with crash injury risk behavior (CIRB) in adolescent Latino males. Waves I and II data from the National Longitudinal Study of Adolescent Health were used. Scale of CIRB, and three relational connections; school connectedness, parent connectedness, and expectation of academic success were developed and tested. Friend nomination data were available and the index student responses were linked to friend responses. Linear regression was used to assess the relationship of relational connections and friend CIRB on index student CIRB at wave I and II. Longitudinal analysis did not show significant evidence for friend influence among adolescent Latino males on CIRB. The best predictor of CIRB at wave II for adolescent Latino males was their CIRB at wave I. Relational connections were important yet exaggerated cross-sectionally but their effect was substantially attenuated longitudinally. The lack of friend influence on CIRB for adolescent Latino males may be specific to this demographic group or characteristic of the sample studied. Prevention strategies that focus on modulating friend influence in adolescent Latino males may not yield the desired prevention effects on CIRB.

Predictive validity of cannabis consumption measures: Results from a national longitudinal study.

PubMed

Buu, Anne; Hu, Yi-Han; Pampati, Sanjana; Arterberry, Brooke J; Lin, Hsien-Chang

2017-10-01

Validating the utility of cannabis consumption measures for predicting later cannabis related symptomatology or progression to cannabis use disorder (CUD) is crucial for prevention and intervention work that may use consumption measures for quick screening. This study examined whether cannabis use quantity and frequency predicted CUD symptom counts, progression to onset of CUD, and persistence of CUD. Data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) at Wave 1 (2001-2002) and Wave 2 (2004-2005) were used to identify three risk samples: (1) current cannabis users at Wave 1 who were at risk for having CUD symptoms at Wave 2; (2) current users without lifetime CUD who were at risk for incident CUD; and (3) current users with past-year CUD who were at risk for persistent CUD. Logistic regression and zero-inflated Poisson models were used to examine the longitudinal effect of cannabis consumption on CUD outcomes. Higher frequency of cannabis use predicted lower likelihood of being symptom-free but it did not predict the severity of CUD symptomatology. Higher frequency of cannabis use also predicted higher likelihood of progression to onset of CUD and persistence of CUD. Cannabis use quantity, however, did not predict any of the developmental stages of CUD symptomatology examined in this study. This study has provided a new piece of evidence to support the predictive validity of cannabis use frequency based on national longitudinal data. The result supports the common practice of including frequency items in cannabis screening tools. Copyright © 2017 Elsevier Ltd. All rights reserved.

Longitudinal elliptically polarized electromagnetic waves in off-diagonal magnetoelectric split-ring composites.

PubMed

Chui, S T; Wang, Weihua; Zhou, L; Lin, Z F

2009-07-22

We study the propagation of plane electromagnetic waves through different systems consisting of arrays of split rings of different orientations. Many extraordinary EM phenomena were discovered in such systems, contributed by the off-diagonal magnetoelectric susceptibilities. We find a mode such that the electric field becomes elliptically polarized with a component in the longitudinal direction (i.e. parallel to the wavevector). Even though the group velocity [Formula: see text] and the wavevector k are parallel, in the presence of damping, the Poynting vector does not just get 'broadened', but can possess a component perpendicular to the wavevector. The speed of light can be real even when the product ϵμ is negative. Other novel properties are explored.

Compensation of shear waves in photoacoustic tomography with layered acoustic media.

PubMed

Schoonover, Robert W; Anastasio, Mark A

2011-10-01

An image reconstruction formula is presented for photoacoustic computed tomography that accounts for conversion between longitudinal and shear waves in a planar-layered acoustic medium. We assume the optical absorber that produces the photoacoustic wave field is embedded in a single fluid layer and any elastic solid layers present are separated by one or more fluid layers. The measurement aperture is assumed to be planar. Computer simulation studies are conducted to demonstrate and investigate the proposed reconstruction formula.

Theory and simulations of radiation friction induced enhancement of laser-driven longitudinal fields

NASA Astrophysics Data System (ADS)

Gelfer, E. G.; Fedotov, A. M.; Weber, S.

2018-06-01

We consider the generation of a quasistatic longitudinal electric field by intense laser pulses propagating in a transparent plasma with radiation friction (RF) taken into account. For both circular and linear polarization of the driving pulse we develop a 1D analytical model of the process, which is valid in a wide range of laser and plasma parameters. We define the parameter region where RF results in an essential enhancement of the longitudinal field. The amplitude and the period of the generated longitudinal wave are estimated and optimized. Our theoretical predictions are confirmed by 1D and 2D PIC simulations. We also demonstrate numerically that RF should substantially enhance the longitudinal field generated in a plasma by a 10 PW laser such as ELI Beamlines.

Examining Longitudinal Relationships between Dysfunctional Career Thoughts and Career Decision-Making Self-Efficacy in School-to-Work Transition

ERIC Educational Resources Information Center

Kim, Boyoung; Lee, Bo Hyun; Ha, Gyuyoung; Lee, Hong Kwon; Lee, Sang Min

2015-01-01

This study examines the role of dysfunctional career thoughts between two-wave longitudinal data (Time 1 and Time 2) in career decision-making self-efficacy during school-to-work transition periods. Career decision-making self-efficacy was measured before (Time 1) and after college graduation (Time 2). The results indicated that the growth of…

Longitudinal Relations among Parenting Styles, Prosocial Behaviors, and Academic Outcomes in U.S. Mexican Adolescents

ERIC Educational Resources Information Center

Carlo, Gustavo; White, Rebecca M. B.; Streit, Cara; Knight, George P.; Zeiders, Katharine H.

2018-01-01

This article examined parenting styles and prosocial behaviors as longitudinal predictors of academic outcomes in U.S. Mexican youth. Adolescents (N = 462; Wave 1 M[subscript age] = 10.4 years; 48.1% girls), parents, and teachers completed parenting, prosocial behavior, and academic outcome measures at 5th, 10th, and 12th grades.…

Predicting Children's Media Use in the USA: Differences in Cross-Sectional and Longitudinal Analysis

ERIC Educational Resources Information Center

Lee, Sook-Jung; Bartolic, Silvia; Vandewater, Elizabeth A.

2009-01-01

The purpose of this paper is to examine the predictors of children's media use in the USA, comparing cross-sectional and longitudinal analyses. Data come from Waves 1 and 2 of the Child Development Supplement (CDS-I; CDS-II), a nationally representative sample of American children aged 0-12 in 1997 and 5-18 in 2002. Twenty-four hour time use…

Quantitative Ray Methods for Scattering of Sound by Spherical Shells

DTIC Science & Technology

1991-08-01

certain anonialxis are discussed . A ray synthesis offsp demonstrates a significant longitudinal resonance effect when kLh = nit, n = 1, 2...computations and experiments with tone burst, certain anomalies are discussed . A ray synthesis offsp 4emorstrates a significant longitudinal resonance effect ...Appendices to Chapter 2 A ) Lemb wave damping parameters, phase velocities, and the effect of the breathing mode ................. 47 Rteferences to

Longitudinal Surveys of Australian Youth (LSAY): 1995 Cohort--User Guide. Data Elements B1: Education. Technical Report 49B1

ERIC Educational Resources Information Center

National Centre for Vocational Education Research (NCVER), 2009

2009-01-01

This technical paper contains information about the variables in the LSAY (Longitudinal Surveys of Australian Youth) Y95 cohort data set. It groups each variable into data elements which identifies common variables within and across waves. Information is provided about each data element including its purpose, values, base populations and relevant.…

Longitudinal relationship of work hours, mandatory overtime, and on-call to musculoskeletal problems in nurses.

PubMed

Trinkoff, Alison M; Le, Rong; Geiger-Brown, Jeanne; Lipscomb, Jane; Lang, Gary

2006-11-01

Nurses are at very high risk for work-related musculoskeletal injury/disorders (MSD) with low back pain/injury being the most frequently occurring MSD. Nurses are also likely to work extended schedules (long hours, on-call, mandatory overtime, working on days off). The purpose of this study was to examine the relationship of extended work schedules in nurses to MSD. Using a longitudinal, three wave survey of 2,617 registered nurses, Wave 1 work schedule data were related to neck, shoulder, and back (MSD) cases occurring in Waves 2 or 3. Schedule characteristics increasing MSD risk included 13+ hour/days, off-shifts, weekend work, work during time off (while sick, on days off, without breaks), and overtime/on-call. These increases in risk were not explained by psychological demands, but were largely explained by physical demands. Adverse schedules are significantly related to nurse MSD. Healthier schedules, less overtime, and reducing work on days off would minimize risk and recovery time. Copyright (c) 2006 Wiley-Liss, Inc.

Pals, problems, and personality: the moderating role of personality in the longitudinal association between adolescents' and best friends' delinquency.

PubMed

Yu, Rongqin; Branje, Susan; Keijsers, Loes; Koot, Hans M; Meeus, Wim

2013-10-01

We examined the potential moderating role of Block's personality types (i.e., overcontrollers, undercontrollers, and resilients) on the longitudinal associations between adolescents' and their best friends' delinquency. Across three annual waves, 497 Dutch adolescents (283 boys, M(Age) = 13 years at Wave 1) and their best friends reported on their delinquent behaviors. Adolescents' three personality types were obtained by latent class growth analysis on their annual reports on Big Five personality. A three-group cross-lagged panel analysis was performed on three waves of data. Delinquency of overcontrollers was predicted by their best friends' delinquency, whereas delinquency of undercontrollers and resilients was not. Delinquency of undercontrollers and resilients predicted their best friends' delinquency, but overcontrollers' delinquency did not. These findings suggest that personality may play an important role in adolescents' susceptibility to the influence of friends' delinquency, as well as in youths' ability to influence friends through their own delinquency. © 2013 Wiley Periodicals, Inc.

Absorption, scattering, and radiation force efficiencies in the longitudinal wave scattering by a small viscoelastic particle in an isotropic solid.

PubMed

Lopes, J H; Leão-Neto, J P; Silva, G T

2017-11-01

Analytical expressions of the absorption, scattering, and elastic radiation force efficiency factors are derived for the longitudinal plane wave scattering by a small viscoelastic particle in a lossless solid matrix. The particle is assumed to be much smaller than the incident wavelength, i.e., the so-called long-wavelength (Rayleigh) approximation. The efficiencies are dimensionless quantities that represent the absorbed and scattering powers and the elastic radiation force on the particle. In the quadrupole approximation, they are expressed in terms of contrast functions (bulk and shear moduli, and density) between the particle and solid matrix. The results for a high-density polyethylene particle embedded in an aluminum matrix agree with those obtained with the partial wave expansion method. Additionally, the connection between the elastic radiation force and forward scattering function is established through the optical theorem. The present results should be useful for ultrasound characterization of particulate composites, and the development of implanted devices activated by radiation force.

Body size estimation and other psychosocial risk factors for obesity onset among US adolescents: findings from a longitudinal population level study.

PubMed

Liechty, J M; Lee, M-J

2015-04-01

The purpose of this study was to examine the longitudinal effects of body size over- and underestimation and other psychosocial factors on the risk for onset of overweight (OW) or obesity (OB) 1 year later among US adolescents. Participants with non-missing height and weight were drawn from the first two waves of the National Longitudinal Study of Adolescent to Adult Health (n=13,568). Multinomial logistic regressions were conducted to assess longitudinal risk factors for OW and OB onset, controlling for baseline weight status, age, race/ethnicity, parent education and family structure. Analyses were stratified by sex. Compared with accurate body size perception, body size overestimation increased the relative risk (RR) of OW onset among women and men (RR=3.34, confidence interval (CI)=2.39-4.68; RR=6.01, CI=4.09-8.83, respectively, P<0.001) in fully adjusted models including body mass index z-scores. Body size underestimation decreased the RR of OW onset among women and men (RR= 0.08, CI=0.03-0.20; RR=0.13, CI=0.06-0.27, respectively) and OB onset (RR=0.05, CI=0.02-0.14; RR=0.19, CI=0.08-0.47, respectively, P<0.001 for all) in fully adjusted models. Dieting, extreme weight loss behaviors and skipping breakfast at Wave 1 increased the risk of OB onset by Wave 2. Contrary to a common assumption, body size underestimation did not increase, but in fact decreased, the RR for the onset of OW and of OB among adolescents using a prospective longitudinal design. However, body size overestimation predicted onset of OW 1 year later. Body size self-concept and other psychosocial factors have an important role in risk for OW and for OB among both males and females during adolescence.

The effect of convection and shear on the damping and propagation of pressure waves

NASA Astrophysics Data System (ADS)

Kiel, Barry Vincent

Combustion instability is the positive feedback between heat release and pressure in a combustion system. Combustion instability occurs in the both air breathing and rocket propulsion devices, frequently resulting in high amplitude spinning waves. If unchecked, the resultant pressure fluctuations can cause significant damage. Models for the prediction of combustion instability typically include models for the heat release, the wave propagation and damping. Many wave propagation models for propulsion systems assume negligible flow, resulting in the wave equation. In this research the effect of flow on wave propagation was studied both numerically and experimentally. Two experiential rigs were constructed, one with axial flow to study the longitudinal waves, the other with swirling flow to study circumferential waves. The rigs were excited with speakers and the resultant pressure was measured simultaneously at many locations. Models of the rig were also developed. Equations for wave propagation were derived from the Euler Equations. The resultant resembled the wave equation with three additional terms, two for the effect of the convection and a one for the effect of shear of the mean flow on wave propagation. From the experimental and numerical data several conclusions were made. First, convection and shear both act as damping on the wave propagation, reducing the magnitude of the Frequency Response Function and the resonant frequency of the modes. Second, the energy extracted from the mean flow as a result of turbulent shear for a given condition is frequency dependent, decreasing with increasing frequency. The damping of the modes, measured for the same shear flow, also decreased with frequency. Finally, the two convective terms cause the anti-nodes of the modes to no longer be stationary. For both the longitudinal and circumferential waves, the anti-nodes move through the domain even for mean flow Mach numbers less than 0.10. It was concluded that convection causes the spinning waves documented in inlets and exhausts of gas turbine engines, rocket combustion chambers, and afterburner chambers. As a result, the effects of shear must be included when modeling wave propagation, even for mean flows less than < Mach 0.10.

Spatio-temporal instabilities for counterpropagating waves in periodic media.

PubMed

Haus, Joseph; Soon, Boon Yi; Scalora, Michael; Bloemer, Mark; Bowden, Charles; Sibilia, Concita; Zheltikov, Alexei

2002-01-28

Nonlinear evolution of coupled forward and backward fields in a multi-layered film is numerically investigated. We examine the role of longitudinal and transverse modulation instabilities in media of finite length with a homogeneous nonlinear susceptibility c((3)). The numerical solution of the nonlinear equations by a beam-propagation method that handles backward waves is described.

The Protective Influence of Family Bonding on Smoking Initiation in Adolescents by Racial/Ethnic and Age Subgroups

ERIC Educational Resources Information Center

Mahabee-Gittens, E. Melinda; Khoury, Jane C.; Huang, Bin; Dorn, Lorah D.; Ammerman, Robert T.; Gordon, Judith S.

2011-01-01

Using data from the National Longitudinal Study of Adolescent Health, this study examined the associations among family bonding factors and the initiation of smoking by race/ethnicity and age group among nonsmokers at Wave 1. Overall, 18% of the sample initiated smoking by Wave 2. For younger African-American and Hispanic youths, high maternal…

Early Adolescent Friendships and Academic Adjustment: Examining Selection and Influence Processes with Longitudinal Social Network Analysis

ERIC Educational Resources Information Center

Shin, Huiyoung; Ryan, Allison M.

2014-01-01

This study investigated early adolescent friendship selection and social influence with regard to academic motivation (self-efficacy and intrinsic value), engagement (effortful and disruptive behavior), and achievement (GPA calculated from report card grades) among 6th graders (N = 587, 50% girls at Wave 1; N = 576, 52% girls at Wave 2) followed…

Wives' Employment and Spouses' Marital Happiness: Assessing the Direction of Influence Using Longitudinal Couple Data

ERIC Educational Resources Information Center

Schoen, Robert; Rogers, Stacy J.; Amato, Paul R.

2006-01-01

The authors investigate the direction of the relationship between marital happiness and wives' full-time employment using the 1987 to 1988 and 1992 to 1994 waves of the National Survey of Families and Households. First, the authors predict change in wives' employment between the two waves using marital happiness and other Time 1 characteristics.…

Developmental Typologies of Identity Formation and Adjustment in Female Emerging Adults: A Latent Class Growth Analysis Approach

ERIC Educational Resources Information Center

Luyckx, Koen; Schwartz, Seth J.; Goossens, Luc; Soenens, Bart; Beyers, Wim

2008-01-01

The developmental interplay between identity and adjustment was examined in a seven-wave longitudinal study of 428 European female college students (M[subscript age] = 18.8 years) over a period of 3 years, with semi-annual measurement waves each year. Latent Class Growth Analysis (LCGA) was used to identify developmental typologies of both…

Assessment of early placental development in the cynomolgus monkey (Macaca fascicularis) using colour and pulsed wave Doppler sonography.

PubMed

Nimrod, C; Simpson, N; Hafner, T; de Vermette, R; Fournier, J; Coady, L; Baccanale, C

1996-04-01

Colour flow mapping and pulsed wave Doppler were used to assess the process of placental growth and development in the cynomolgus monkey from 32 to 71 days gestational age. Fetal and maternal vessels were reliably visualised and insonated. Accurate longitudinal non-invasive assessment of placentation is possible using this technique.

Electro-opto-mechanical radio-frequency oscillator driven by guided acoustic waves in standard single-mode fiber

NASA Astrophysics Data System (ADS)

London, Yosef; Diamandi, Hilel Hagai; Zadok, Avi

2017-04-01

An opto-electronic radio-frequency oscillator that is based on forward scattering by the guided acoustic modes of a standard single-mode optical fiber is proposed and demonstrated. An optical pump wave is used to stimulate narrowband, resonant guided acoustic modes, which introduce phase modulation to a co-propagating optical probe wave. The phase modulation is converted to an intensity signal at the output of a Sagnac interferometer loop. The intensity waveform is detected, amplified, and driven back to modulate the optical pump. Oscillations are achieved at a frequency of 319 MHz, which matches the resonance of the acoustic mode that provides the largest phase modulation of the probe wave. Oscillations at the frequencies of competing acoustic modes are suppressed by at least 40 dB. The linewidth of the acoustic resonance is sufficiently narrow to provide oscillations at a single longitudinal mode of the hybrid cavity. Competing longitudinal modes are suppressed by at least 38 dB as well. Unlike other opto-electronic oscillators, no radio-frequency filtering is required within the hybrid cavity. The frequency of oscillations is entirely determined by the fiber opto-mechanics.

Sound pressure distribution within natural and artificial human ear canals: forward stimulation.

PubMed

Ravicz, Michael E; Tao Cheng, Jeffrey; Rosowski, John J

2014-12-01

This work is part of a study of the interaction of sound pressure in the ear canal (EC) with tympanic membrane (TM) surface displacement. Sound pressures were measured with 0.5-2 mm spacing at three locations within the shortened natural EC or an artificial EC in human temporal bones: near the TM surface, within the tympanic ring plane, and in a plane transverse to the long axis of the EC. Sound pressure was also measured at 2-mm intervals along the long EC axis. The sound field is described well by the size and direction of planar sound pressure gradients, the location and orientation of standing-wave nodal lines, and the location of longitudinal standing waves along the EC axis. Standing-wave nodal lines perpendicular to the long EC axis are present on the TM surface >11-16 kHz in the natural or artificial EC. The range of sound pressures was larger in the tympanic ring plane than at the TM surface or in the transverse EC plane. Longitudinal standing-wave patterns were stretched. The tympanic-ring sound field is a useful approximation of the TM sound field, and the artificial EC approximates the natural EC.

Reconstruction of the temperature field for inverse ultrasound hyperthermia calculations at a muscle/bone interface.

PubMed

Liauh, Chihng-Tsung; Shih, Tzu-Ching; Huang, Huang-Wen; Lin, Win-Li

2004-02-01

An inverse algorithm with Tikhonov regularization of order zero has been used to estimate the intensity ratios of the reflected longitudinal wave to the incident longitudinal wave and that of the refracted shear wave to the total transmitted wave into bone in calculating the absorbed power field and then to reconstruct the temperature distribution in muscle and bone regions based on a limited number of temperature measurements during simulated ultrasound hyperthermia. The effects of the number of temperature sensors are investigated, as is the amount of noise superimposed on the temperature measurements, and the effects of the optimal sensor location on the performance of the inverse algorithm. Results show that noisy input data degrades the performance of this inverse algorithm, especially when the number of temperature sensors is small. Results are also presented demonstrating an improvement in the accuracy of the temperature estimates by employing an optimal value of the regularization parameter. Based on the analysis of singular-value decomposition, the optimal sensor position in a case utilizing only one temperature sensor can be determined to make the inverse algorithm converge to the true solution.

An experimental evaluation of two effective medium theories for ultrasonic wave propagation in concrete.

PubMed

Chaix, Jean-François; Rossat, Mathieu; Garnier, Vincent; Corneloup, Gilles

2012-06-01

This study compares ultrasonic wave propagation modeling and experimental data in concrete. As a consequence of its composition and manufacturing process, this material has a high elastic scattering (sand and aggregates) and air (microcracks and porosities) content. The behavior of the "Waterman-Truell" and "Generalized Self Consistent Method" dynamic homogenization models are analyzed in the context of an application for strong heterogeneous solid materials, in which the scatterers are of various concentrations and types. The experimental validations of results predicted by the models are carried out by making use of the phase velocity and the attenuation of longitudinal waves, as measured by an immersed transmission setup. The test specimen material has a cement-like matrix containing spherical inclusions of air or glass, with radius close to the ultrasonic wavelength. The models are adapted to the case of materials presenting several types of scattering particle, and allow the propagation of longitudinal waves to be described at the scale of materials such as concrete. The validity limits for frequency and for particle volume ratio can be approached through a comparison with experimental data. The potential of these homogenization models for the prediction of phase velocity and attenuation in strongly heterogeneous solids is demonstrated.

Scale-dependent effects on wave propagation in magnetically affected single/double-layered compositionally graded nanosize beams

NASA Astrophysics Data System (ADS)

Ebrahimi, Farzad; Barati, Mohammad Reza

2018-04-01

This article deals with the wave propagation analysis of single/double layered functionally graded (FG) size-dependent nanobeams in elastic medium and subjected to a longitudinal magnetic field employing nonlocal elasticity theory. Material properties of nanobeam change gradually according to the sigmoid function. Applying an analytical solution, the acoustical and optical dispersion relations are explored for various wave number, nonlocality parameter, material composition, elastic foundation constants, and magnetic field intensity. It is found that frequency and phase velocity of waves propagating in S-FGM nanobeam are significantly affected by these parameters. Also, presence of cut-off and escape frequencies in wave propagation analysis of embedded S-FGM nanobeams is investigated.

Nonlinear layered lattice model and generalized solitary waves in imperfectly bonded structures.

PubMed

Khusnutdinova, Karima R; Samsonov, Alexander M; Zakharov, Alexey S

2009-05-01

We study nonlinear waves in a two-layered imperfectly bonded structure using a nonlinear lattice model. The key element of the model is an anharmonic chain of oscillating dipoles, which can be viewed as a basic lattice analog of a one-dimensional macroscopic waveguide. Long nonlinear longitudinal waves in a layered lattice with a soft middle (or bonding) layer are governed by a system of coupled Boussinesq-type equations. For this system we find conservation laws and show that pure solitary waves, which exist in a single equation and can exist in the coupled system in the symmetric case, are structurally unstable and are replaced with generalized solitary waves.

Waves and instabilities in an anisotropic universe

NASA Astrophysics Data System (ADS)

Papadopoulos, D.; Vlahos, L.; Esposito, F. P.

2002-01-01

The excitation of low frequency plasma waves in an expanding anisotropic cosmological model that contains a magnetic field frozen into the matter and pointing in the longitudinal direction is discussed. Using the exact equations governing finite-amplitude wave propagation in hydromagnetic media within the framework of the general theory of relativity, we show that a spectrum of magnetized sound waves will be excited and form large-scale ``damped oscillations'' in the expanding universe. The characteristic frequency of the excited waves is slightly shifted away from the sound frequency and the shift depends on the strength of the primordial magnetic field. This magnetic field dependent shift may have an effect on the acoustic peaks of the CMB.

Effects of exposure to violence with a weapon during adolescence on adult hypertension.

PubMed

Ford, Jodi L; Browning, Christopher R

2014-03-01

To examine the longitudinal associations between exposure to violence with a weapon during the past year among adolescents and hypertension during adulthood, including the extent to which adult cardiovascular risk factors mediated the association. Secondary analysis of the National Longitudinal Study of Adolescent Health, 1994-2008. The sample included 3555 male and 4416 female participants who were aged 11-17 years at wave 1 (1994-1995). Participants were categorized as hypertensive if they had a mean systolic blood pressure of 140 mm Hg or higher or a mean diastolic pressure of 90 mm Hg or higher at wave 4 (2008). Witnessed violence with a weapon was defined as having seen a shooting or stabbing during the year before wave 1, whereas victim of violence with a weapon was defined as having been shot, cut, or stabbed or had a gun or knife drawn on them during the year before wave 1. Potential mediators of adult cardiovascular risk (wave 4) included body mass index, daily smoking, alcohol abuse, and depression. Males who witnessed violence and females who were victims of violence in the year before wave 1 had an increased odds of hypertension at wave 4 compared with their unexposed peers (adjusted odds ratio, 1.45; 95% confidence interval, 1.003-2.10 and adjusted odds ratio, 1.72; 95% confidence interval, 1.04-2.84, respectively). The hypothesized adult cardiovascular risk mediators did not significantly attenuate the associations for either the male or female samples. Interventions addressing prior violence exposure are needed to promote adult cardiovascular health. Copyright © 2014 Elsevier Inc. All rights reserved.

Japanese Study on Stratification, Health, Income, and Neighborhood: Study Protocol and Profiles of Participants

PubMed Central

Takada, Misato; Kondo, Naoki; Hashimoto, Hideki

2014-01-01

Background The Japanese Study on Stratification, Health, Income, and Neighborhood (J-SHINE) aims to clarify the complex associations between social factors and health from an interdisciplinary perspective and to provide a database for use in various health policy evaluations. Methods J-SHINE is an ongoing longitudinal panel study of households of adults aged 25–50 years. The wave 1 survey was carried out in 2010 among adults randomly selected from the resident registry of four urban and suburban municipalities in the greater Tokyo metropolitan area, Japan. In 2011, surveys for the participants’ spouse/partner and child were additionally conducted. The wave 2 survey was conducted in 2012 for the wave 1 participants and will be followed by the wave 2 survey for spouse/partner and child in 2013. Results Wave 1 sample sizes were 4357 for wave 1 participants (valid response rate: 31.3%; cooperation rate: 51.8%), 1873 for spouse/partner (response rate: 61.9%), and 1520 for child (response rate: 67.7%). Wave 2 captured 69.0% of wave 1 participants. Information gathered covered socio-demographics, household economy, self-reported health conditions and healthcare utilization, stress and psychological values, and developmental history. A subpopulation underwent physiological (n = 2468) and biomarker (n = 1205) measurements. Conclusions Longitudinal survey data, including repeated measures of social factors evaluated based on theories and techniques of various disciplines, like J-SHINE, should contribute toward opening a web of causality for society and health, which may have important policy implications for recent global health promotion strategies such as the World Health Organization’s Social Determinants of Health approach and the second round of Japan’s Healthy Japan 21. PMID:24814507

Japanese study on stratification, health, income, and neighborhood: study protocol and profiles of participants.

PubMed

Takada, Misato; Kondo, Naoki; Hashimoto, Hideki

2014-01-01

The Japanese Study on Stratification, Health, Income, and Neighborhood (J-SHINE) aims to clarify the complex associations between social factors and health from an interdisciplinary perspective and to provide a database for use in various health policy evaluations. J-SHINE is an ongoing longitudinal panel study of households of adults aged 25-50 years. The wave 1 survey was carried out in 2010 among adults randomly selected from the resident registry of four urban and suburban municipalities in the greater Tokyo metropolitan area, Japan. In 2011, surveys for the participants' spouse/partner and child were additionally conducted. The wave 2 survey was conducted in 2012 for the wave 1 participants and will be followed by the wave 2 survey for spouse/partner and child in 2013. Wave 1 sample sizes were 4357 for wave 1 participants (valid response rate: 31.3%; cooperation rate: 51.8%), 1873 for spouse/partner (response rate: 61.9%), and 1520 for child (response rate: 67.7%). Wave 2 captured 69.0% of wave 1 participants. Information gathered covered socio-demographics, household economy, self-reported health conditions and healthcare utilization, stress and psychological values, and developmental history. A subpopulation underwent physiological (n = 2468) and biomarker (n = 1205) measurements. Longitudinal survey data, including repeated measures of social factors evaluated based on theories and techniques of various disciplines, like J-SHINE, should contribute toward opening a web of causality for society and health, which may have important policy implications for recent global health promotion strategies such as the World Health Organization's Social Determinants of Health approach and the second round of Japan's Healthy Japan 21.

Gender differences in self-reported withdrawal symptoms and reducing or quitting smoking three years later: A prospective, longitudinal examination of U.S. adults

PubMed Central

Weinberger, Andrea H.; Platt, Jonathan; Shuter, Jonathan; Goodwin, Renee D.

2016-01-01

Background Little is known about gender differences in withdrawal symptoms among smokers in the community. This study used longitudinal epidemiologic data to examine gender differences in current smokers’ report of withdrawal symptoms during past quit attempts and the relationship between withdrawal symptoms and the odds of reducing or quitting smoking three years later. Methods Data were drawn from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; Wave 1, 2001–2001, n=43,093; Wave 2, 2004–2005, n=34,653). Analyses were conducted on respondents who reported current daily cigarette smoking at Wave 1 (n=6,911). Withdrawal symptoms during past quit attempts were assessed at Wave 1. Current smoking status was assessed at Wave 2. Results Wave 1 current smoking women, compared to men, were more likely to endorse any withdrawal symptoms, withdrawal-related discomfort, and withdrawal-related relapse (ps<0.0001). Women endorsed a greater number of withdrawal symptoms than men (M=2.37, SE=0.05 versus M=1.78, SE=0.04; p<0.0001). The odds of reducing and quitting smoking were significantly lower for respondents who reported any Wave 1 withdrawal symptoms, withdrawal-related discomfort, and withdrawal-related relapse. These relationships did not differ for women versus men. Among men, the odds of reducing smoking at Wave 2 decreased significantly with each cumulative withdrawal symptom compared to women (β interaction= 0.87; p=0.01). Conclusions Women were more likely to report withdrawal while the relationship between withdrawal symptoms and decreased likelihood of reducing smoking was stronger in men. Identifying gender differences in withdrawal can help develop strategies to help reduce withdrawal for both men and women. PMID:27350655

Ultrasonic longitudinal waves to monitor the integration of titanium rods with host bone

NASA Astrophysics Data System (ADS)

Wang, Wentao; Lynch, Jerome P.

2017-04-01

Osseointegrated prostheses which integrate the prosthesis directly to the limb bone are being developed for patients that are unable to wear traditional socket prostheses. While osseointegration of the prosthesis offers amputees improvement in their quality of life, there remains a need to better understand the integration process that occurs between the bone and the prosthesis. Quantification of the degree of integration is important to track the recuperation process of the amputee, guide physical therapy regimes, and to identify when the state of integration may change (due to damage to the bone). This study explores the development of an assessment strategy for quantitatively assessing the degree of integration between an osseointegrated prosthesis and host bone. Specifically, the strategy utilizes a titanium rod prosthesis as a waveguide with guided waves used to assess the degree of integration. By controlling waveforms launched by piezoelectric wafers bonded on the percutaneous tip of the prosthesis, body waves are introduced into the waveguide with wave reflections at the boneprosthesis interface recorded by the same array. Changes in wave energy are correlated to changes at the contact interface between the titanium rod and the bone material. Both simulation and experimental tests are presented in this paper. Experimental testing is performed using a high-density polyethylene (HDPE) host because the elastic modulus and density of HDPE are close to that of human and animal bone. Results indicate high sensitivity of the longitudinal wave energy to rod penetration depth and confinement stress issued by the host bone.

Study Addiction: A Cross-Cultural Longitudinal Study Examining Temporal Stability and Predictors of Its Changes

PubMed Central

Atroszko, Paweł Andrzej; Andreassen, Cecilie Schou; Griffiths, Mark D.; Pallesen, Ståle

2016-01-01

Background and aims “Study addiction” has recently been conceptualized as a behavioral addiction and defined within the framework of work addiction. Using a newly developed measure to assess this construct, the Bergen Study Addiction Scale (BStAS), the present study examined the 1-year stability of study addiction and factors related to changes in this construct over time, and is the first longitudinal investigation of study addiction thus far. Methods The BStAS and the Ten Item Personality Inventory were administered online together with questions concerning demographics and study-related variables in two waves. In Wave 1, a total of 2,559 students in Norway and 2,177 students in Poland participated. A year later, in Wave 2, 1,133 Norwegians and 794 Polish, who were still students completed the survey. Results The test–retest reliability coefficients for the BStAS revealed that the scores were relatively stable over time. In Norway, scores on the BStAS were higher in Wave 2 than in Wave 1, whereas in Poland, the reverse pattern was observed. Learning time outside classes at Wave 1 was positively related to escalation of study addiction symptoms over time in both samples. Being female and scoring higher on neuroticism was related to an increase in study addiction in the Norwegian sample only. Conclusions Study addiction appears to be temporally stable, and the amount of learning time spent outside classes predicts changes in study addiction 1 year later. PMID:27156381

Does Depression Moderate or Mediate the Relations between Deficits in Competence and Aggression?: A Short-Term Longitudinal Study of Korean Children

ERIC Educational Resources Information Center

Shin, Hyeonsook

2010-01-01

This study was conducted to examine the role of child depression in the relations between deficits in competence and aggression by replicating and extending the study by Cole et al. (1996). In a two-wave longitudinal study, 6th-grade children (n = 329) completed self-report measures of three domains of competence (i.e. social, academic,…

Does Parenting Shield Youth from Exposure to Violence during Adolescence? A 5-Year Longitudinal Test in a High-Poverty Sample of Minority Youth

ERIC Educational Resources Information Center

Spano, Richard; Rivera, Craig; Bolland, John M.

2011-01-01

Five waves of longitudinal data collected from 349 African American youth living in extreme poverty were used to determine if parental monitoring shielded youth from exposure to violence during adolescence. Semiparametric group-based modeling was used to identify trajectories of parental monitoring and exposure to violence from T1 to T5. Results…

Preschoolers with Disabilities: Characteristics, Services, and Results. Wave 1 Overview Report from the Pre-Elementary Education Longitudinal Study (PEELS). NCSER 2006-3003

ERIC Educational Resources Information Center

Markowitz, Joy; Carlson, Elaine; Frey, William; Riley, Jarnee; Shimshak, Amy; Heinzen, Harriotte; Strohl, Jeff; Klein, Sheri; Hyunshik, Lee

2006-01-01

The Pre-Elementary Education Longitudinal Study, commonly referred to as the PEELS study, is funded by the U.S. Department of Education's National Center for Special Education Research (NCSER). It will follow a nationally representative sample of children with disabilities ages 3-5 for a period of six years. This study is designed to describe the…

The Dual Impact of Gender and the Influence of Timing of Parenthood on Men's and Women's Career Development: Longitudinal Findings

ERIC Educational Resources Information Center

Abele, Andrea E.; Spurk, Daniel

2011-01-01

This study investigated the impact of gender, the gender-related self-concept (agency and communion), and the timing of parenthood on objective career success of 1,015 highly educated professionals. Hypotheses derived from a dual-impact model of gender and career-related processes were tested in a 5-wave longitudinal study over a time span of 10…

How do Rumination and Social Problem Solving Intensify Depression? A Longitudinal Study.

PubMed

Hasegawa, Akira; Kunisato, Yoshihiko; Morimoto, Hiroshi; Nishimura, Haruki; Matsuda, Yuko

2018-01-01

In order to examine how rumination and social problem solving intensify depression, the present study investigated longitudinal associations among each dimension of rumination and social problem solving and evaluated aspects of these constructs that predicted subsequent depression. A three-wave longitudinal study, with an interval of 4 weeks between waves, was conducted. Japanese university students completed the Beck Depression Inventory-Second Edition, Ruminative Responses Scale, Social Problem-Solving Inventory-Revised Short Version, and Interpersonal Stress Event Scale on three occasions 4 weeks apart ( n  = 284 at Time 1, 198 at Time 2, 165 at Time 3). Linear mixed models were analyzed to test whether each variable predicted subsequent depression, rumination, and each dimension of social problem solving. Rumination and negative problem orientation demonstrated a mutually enhancing relationship. Because these two variables were not associated with interpersonal conflict during the subsequent 4 weeks, rumination and negative problem orientation appear to strengthen each other without environmental change. Rumination and impulsivity/carelessness style were associated with subsequent depressive symptoms, after controlling for the effect of initial depression. Because rumination and impulsivity/carelessness style were not concurrently and longitudinally associated with each other, rumination and impulsive/careless problem solving style appear to be independent processes that serve to intensify depression.

High-pressure ultrasonic study of the commensurate-incommensurate spin-density-wave transition in an antiferromagnetic Cr-0.3 at. % Ru alloy single crystal

NASA Astrophysics Data System (ADS)

Cankurtaran, M.; Saunders, G. A.; Wang, Q.; Ford, P. J.; Alberts, H. L.

1992-12-01

A comprehensive experimental study has been made of the elastic and nonlinear acoustic behavior of a dilute Cr alloy as it undergoes a commensurate (C)-incommensurate (I) spin-density-wave transition. Simultaneous measurements of the temperature dependence of ultrasonic wave velocity and attenuation of longitudinal and shear 10-MHz ultrasonic waves propagated along both the [100] and the [110] direction of Cr-0.3 at. % Ru alloy single crystal have been made in the temperature range 200-300 K. The temperature dependence of ultrasonic attenuation for each mode is characterized by a spikelike peak centered at TCI (=238.6 K) (on cooling) and at TIC (=255.6 K) (on warming). The velocities of both longitudinal and shear ultrasonic waves exhibit a large and steep increase at TCI on cooling and a similar drop at TIC on warming with a pronounced hysteresis between TIC and TCI. These observations show that the transition between the commensurate and incommensurate phases is first order. Measurements of the effects of hydrostatic pressure (up to 0.15 GPa) on the velocities of ultrasonic waves, which were made at several fixed temperatures between 248 and 297 K, show similar features: a steep increase at PCI (increasing pressure) and a similar drop at PIC (decreasing pressure) with a well-defined hysteresis. Both TCI and TIC increase strongly and approximately linearly with pressure, the mean values of dTCI/dP and dTIC/dP being (333+/-3) K/GPa and (277+/-5) K/GPa, respectively. The pressure and temperature dependencies of the anomalies in the ultrasonic wave velocity have been used to locate both the C-I and I-C boundaries on the magnetic P-T phase diagram. There is a triple point (at about 315 K and 0.22 GPa) where the paramagnetic, commensurate, and incommensurate spin-density-wave phases coexist. Results for the complete sets of the elastic stiffness tensor components and their hydrostatic pressure derivatives have been used to evaluate the acoustic-mode Grüneisen parameters in both the commensurate and incommensurate phases. These quantify the vibrational anharmonicity of each acoustic phonon mode in the long-wavelength limit and establish which acoustic modes interact strongly with the spin-density waves. Pronounced longitudinal acoustic-mode softening under pressure results in negative Grüneisen parameters, a particularly marked feature of the commensurate phase.

Does Pain Predict Frailty in Older Men and Women? Findings From the English Longitudinal Study of Ageing (ELSA).

PubMed

Wade, Katie F; Marshall, Alan; Vanhoutte, Bram; Wu, Frederick C W; O'Neill, Terence W; Lee, David M

2017-03-01

Pain has been suggested to act as a stressor during aging, potentially accelerating declines in health and functioning. Our objective was to examine the longitudinal association between self-reported pain and the development, or worsening, of frailty among older men and women. The study population consisted of 5,316 men and women living in private households in England, mean age 64.5 years, participating in the English Longitudinal Study of Ageing (ELSA). Data from Waves 2 and 6 of ELSA were used in this study with 8 years of follow-up. At Wave 2, participants were asked whether they were "often troubled with pain" and for those who reported yes, further information regarding the intensity of their pain (mild, moderate, or severe) was collected. Socioeconomic status (SES) was assessed using information about the current/most recent occupation and also net wealth. A frailty index (FI) was generated, with the presence of frailty defined as an FI >0.35. Among those without frailty at Wave 2, the association between pain at Wave 2 and frailty at Wave 6 was examined using logistic regression. We investigated whether pain predicted change in FI between Waves 2 and 6 using a negative binomial regression model. For both models adjustments were made for age, gender, lifestyle factors, depressive symptoms, and socioeconomic factors. At Wave 2, 455 (19.7%) men and 856 (28.7%) women reported they often experienced moderate or severe pain. Of the 5,159 participants who were nonfrail at Wave 2, 328 (6.4%) were frail by Wave 6. The mean FI was 0.11 (standard deviation [SD] = 0.1) at Wave 2 and 0.15 (SD = 0.1) at Wave 6. After adjustment for age, gender, body mass index, lifestyle factors, and depressive symptoms, compared to participants reporting no pain at Wave 2 those reporting moderate (odds ratio [OR] = 3.08, 95% confidence interval [CI] = 2.28, 4.16) or severe pain (OR = 3.78, 95% CI = 2.51, 5.71) were significantly more likely to be frail at Wave 6. This association persisted after further adjustment for either occupational class and/or net wealth level. Compared to those without pain, those with mild, moderate, or severe pain were also more likely to develop worsening frailty, as assessed using the FI, and this association persisted after adjustment for SES. There was no evidence that the association between pain and frailty was influenced by gender. Pain is associated with an increased risk and intensity of frailty in older men and women. Socioeconomic factors contribute to the occurrence of frailty; though in our study do not explain the relationship between pain and frailty. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America.

Explicating the Conditions Under Which Multilevel Multiple Imputation Mitigates Bias Resulting from Random Coefficient-Dependent Missing Longitudinal Data.

PubMed

Gottfredson, Nisha C; Sterba, Sonya K; Jackson, Kristina M

2017-01-01

Random coefficient-dependent (RCD) missingness is a non-ignorable mechanism through which missing data can arise in longitudinal designs. RCD, for which we cannot test, is a problematic form of missingness that occurs if subject-specific random effects correlate with propensity for missingness or dropout. Particularly when covariate missingness is a problem, investigators typically handle missing longitudinal data by using single-level multiple imputation procedures implemented with long-format data, which ignores within-person dependency entirely, or implemented with wide-format (i.e., multivariate) data, which ignores some aspects of within-person dependency. When either of these standard approaches to handling missing longitudinal data is used, RCD missingness leads to parameter bias and incorrect inference. We explain why multilevel multiple imputation (MMI) should alleviate bias induced by a RCD missing data mechanism under conditions that contribute to stronger determinacy of random coefficients. We evaluate our hypothesis with a simulation study. Three design factors are considered: intraclass correlation (ICC; ranging from .25 to .75), number of waves (ranging from 4 to 8), and percent of missing data (ranging from 20 to 50%). We find that MMI greatly outperforms the single-level wide-format (multivariate) method for imputation under a RCD mechanism. For the MMI analyses, bias was most alleviated when the ICC is high, there were more waves of data, and when there was less missing data. Practical recommendations for handling longitudinal missing data are suggested.

When is a carer's employment at risk? Longitudinal analysis of unpaid care and employment in midlife in England.

PubMed

King, Derek; Pickard, Linda

2013-05-01

This article examines the thresholds at which provision of unpaid care affects employment in England. Previous research has shown that providing care for 20 or more hours a week has a negative effect on employment. The present article explores the impact of a lower threshold and asks whether provision of care for 10 or more hours a week has a negative effect on employment. The article focuses on women and men aged between 50 and State Pension Age (60 for women, 65 for men). The study uses data from the first four waves of the English Longitudinal Study of Ageing (ELSA), collected in 2002/2003, 2004/2005, 2006/2007 and 2008/2009. Across these waves, there are 17,123 people aged 50-59/64 years, of whom 9% provide unpaid care to an adult. Using logistic regression analysis of the longitudinal data, the study finds that employed women in their fifties who start providing care for <10 hours a week are significantly more likely to remain in employment one wave later than similar women who have not started to provide care. In contrast, employed women in their fifties who start providing care for 10 or more hours a week are significantly less likely to remain in employment one wave later than similar women who have not started to provide care. Employed men aged between 50 and State Pension Age, who provide care for 10 or more hours a week at the beginning of the period have a significantly reduced employment rate one wave later than those who do not provide care. The study therefore suggests that carers' employment may be negatively affected when care is provided at a lower intensity than is generally estimated in England. This has important implications for local authorities, who have a duty to provide services to carers whose employment is at risk. © 2013 Blackwell Publishing Ltd.

On propagation of axisymmetric waves in pressurized functionally graded elastomeric hollow cylinders

NASA Astrophysics Data System (ADS)

Wu, Bin; Su, Yipin; Liu, Dongying; Chen, Weiqiu; Zhang, Chuanzeng

2018-05-01

Soft materials can be designed with a functionally graded (FG) property for specific applications. Such material inhomogeneity can also be found in many soft biological tissues whose functionality is only partly understood to date. In this paper, we analyze the axisymmetric guided wave propagation in a pressurized FG elastomeric hollow cylinder. The cylinder is subjected to a combined action of axial pre-stretch and pressure difference applied to the inner and outer cylindrical surfaces. We consider both torsional waves and longitudinal waves propagating in the FG cylinder made of incompressible isotropic elastomer, which is characterized by the Mooney-Rivlin strain energy function but with the material parameters varying with the radial coordinate in an affine way. The pressure difference generates an inhomogeneous deformation field in the FG cylinder, which dramatically complicates the superimposed wave problem described by the small-on-large theory. A particularly efficient approach is hence employed which combines the state-space formalism for the incremental wave motion with the approximate laminate or multi-layer technique. Dispersion relations for the two types of axisymmetric guided waves are then derived analytically. The accuracy and convergence of the proposed approach is validated numerically. The effects of the pressure difference, material gradient, and axial pre-stretch on both the torsional and the longitudinal wave propagation characteristics are discussed in detail through numerical examples. It is found that the frequency of axisymmetric waves depends nonlinearly on the pressure difference and the material gradient, and an increase in the material gradient enhances the capability of the pressure difference to adjust the wave behavior in the FG cylinder. This work provides a theoretical guidance for characterizing FG soft materials by in-situ ultrasonic nondestructive evaluation and for designing tunable waveguides via material tailoring along with an adjustment of the pre-stretch and pressure difference.

Glycosylated hemoglobin testing in the National Social Life, Health, and Aging Project.

PubMed

Gregg, Forest T; O'Doherty, Katie; Schumm, L Philip; McClintock, Martha K; Huang, Elbert S

2014-11-01

Longitudinal biomeasures of health are still new in nationally representative social science survey research. Data measuring blood sugar control provide opportunities for understanding the development of diabetes and its complications in older adults, but researchers must be aware that some of the differences across time can be due to variations in measurement procedures. This is a well-recognized issue whenever all samples cannot be assayed at the same time and we sought to present the analytic methods to quantify and adjust for the variation. We collected and analyzed HbA1C, glycated hemoglobin, a biomeasure of average blood sugar concentrations within the past few months. Improvements were made in the collection protocol for Wave 2, and assays were performed by a different lab. The HbA1C data obtained during Wave 1 and Wave 2 are consistent with the expected population distributions for differences by gender, age, race/ethnicity, and diabetes status. Age-adjusted mean HbA1C declined slightly from Wave 1 to Wave 2 by -0.19 (95% confidence interval [CI]: -0.27, -0.10), and the average longitudinal change was -0.12 (95% CI: -0.18, -0.06). Collection of HbA1C in Wave 2 permits researchers to examine the relationship between HbA1C and new health and social measures added in Wave 2, and to identify factors related to the change in HbA1C. Changes in collection protocol and labs between waves may have yielded small systematic differences that require analysts to carefully interpret absolute HbA1C values. We recommend analytic methods for cross wave differences in HbA1C and steps to ensure cross wave comparability in future studies. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Inverse Edelstein effect induced by magnon-phonon coupling

NASA Astrophysics Data System (ADS)

Xu, Mingran; Puebla, Jorge; Auvray, Florent; Rana, Bivas; Kondou, Kouta; Otani, Yoshichika

2018-05-01

We demonstrate a spin to charge current conversion via magnon-phonon coupling and an inverse Edelstein effect on the hybrid device Ni/Cu (Ag )/Bi 2O3 . The generation of spin current (Js≈108A/m2 ) due to magnon-phonon coupling reveals the viability of acoustic spin pumping as a mechanism for the development of spintronic devices. A full in-plane magnetic field angle dependence of the power absorption and a combination of longitudinal and transverse voltage detection reveals the symmetric and asymmetric components of the inverse Edelstein effect voltage induced by Rayleigh-type surface acoustic waves. While the symmetric components are well studied, asymmetric components still need to be explored. We assign the asymmetric contributions to the interference between longitudinal and shear waves and an anisotropic charge distribution in our hybrid device.

Low-Temperature Variation of Acoustic Velocity in PDMS for High-Frequency Applications.

PubMed

Streque, Jeremy; Rouxel, Didier; Talbi, Abdelkrim; Thomassey, Matthieu; Vincent, Brice

2018-05-01

Polydimethylsiloxane (PDMS) and other related silicon-based polymers are among the most widely employed elastomeric materials in microsystems, owing to their physical and chemical properties. Meanwhile, surface acoustic wave (SAW) and bulk acoustic wave (BAW) sensors and filters have been vastly explored for sensing and wireless applications. Many fields could benefit from the combined use of acoustic wave devices, and polydimethylsiloxane-based soft-substrates, microsystems, or packaging elements. The mechanical constants of PDMS strongly depend on frequency, similar to rubber materials. This brings to the exploration of the specific mechanical properties of PDMS encountered at high frequency, required for its exploitation in SAW or BAW devices. First, low-frequency mechanical behavior is confirmed from stress strain measurements, remaining useful for the exploitation of PDMS as a soft substrate or packaging material. The study, then, proposes a temperature-dependent, high-frequency mechanical study of PDMS based on Brillouin spectroscopy to determine the evolution of the longitudinal acoustic velocity in this material, which constitutes the main mechanical parameter for the design of acoustic wave devices. The PDMS glass transition is then retrieved by differential scanning calorimetry in order to confirm the observations made by Brillouin spectroscopy. This paper validates Brillouin spectroscopy as a very suitable characterization technique for the retrieval of longitudinal mechanical properties at low temperature, as a preliminary investigation for the design of acoustic wave devices coupled with soft materials.

U.S. Army Deployment Resilience & Retention: Wave II

DTIC Science & Technology

2014-08-04

recovery from stressful and sometimes traumatic experiences. Implications for Military Nursing : This research is instrumental in understanding the ...frequency, length, location) on job and family stresses and strains of the soldiers. Using longitudinal data from both Waves 1 and 2 (N=382) we...predicted, more support was related to a decline in depression. In contrast among those who experienced low levels of combat exposure, the association

The Potential Energy Density in Transverse String Waves Depends Critically on Longitudinal Motion

ERIC Educational Resources Information Center

Rowland, David R.

2011-01-01

The question of the correct formula for the potential energy density in transverse waves on a taut string continues to attract attention (e.g. Burko 2010 "Eur. J. Phys." 31 L71), and at least three different formulae can be found in the literature, with the classic text by Morse and Feshbach ("Methods of Theoretical Physics" pp 126-127) stating…

Transactional Links between Teacher-Child Relationship Quality and Perceived versus Sociometric Popularity: A Three-Wave Longitudinal Study

ERIC Educational Resources Information Center

De Laet, Steven; Doumen, Sarah; Vervoort, Eleonora; Colpin, Hilde; Van Leeuwen, Karla; Goossens, Luc; Verschueren, Karine

2014-01-01

This study examined how peer relationships (i.e., sociometric and perceived popularity) and teacher--child relationships (i.e., support and conflict) impact one another throughout late childhood. The sample included 586 children (46% boys), followed annually from Grades 4 to 6 (Mage.wave1 = 9.26 years). Autoregressive cross-lagged modeling was…

Global Gravity Wave Variances from Aura MLS: Characteristics and Interpretation

DTIC Science & Technology

2008-12-01

slight longitudinal variations, with secondary high- latitude peaks occurring over Greenland and Europe . As the QBO changes to the westerly phase, the...equatorial GW temperature variances from suborbital data (e.g., Eck- ermann et al. 1995). The extratropical wave variances are generally larger in the...emanating from tropopause altitudes, presumably radiated from tropospheric jet stream in- stabilities associated with baroclinic storm systems that

Do Grades Shape Students' School Engagement? The Psychological Consequences of Report Card Grades at the Beginning of Secondary School

ERIC Educational Resources Information Center

Poorthuis, Astrid M. G.; Juvonen, Jaana; Thomaes, Sander; Denissen, Jaap J. A.; de Castro, Bram Orobio; van Aken, Marcel A. G.

2015-01-01

Receiving report card grades is psychologically salient to most students and can elicit a range of affective reactions. A 3-wave longitudinal study examined how grades shape students' (N = 375; M age at Wave 1 = 12.6 years) school engagement through the affective reactions they elicit. Emotional and behavioral engagement were measured at the start…

Anisotropic determination and correction for ultrasonic flaw detection by spectral analysis

DOEpatents

Adler, Laszlo; Von Cook, K.; Simpson, Jr., William A.; Lewis, D. Kent

1978-01-01

The anisotropic nature of a material is determined by measuring the velocity of an ultrasonic longitudinal wave and a pair of perpendicular ultrasonic shear waves through a sample of the material each at a plurality of different angles in three planes orthogonal to each other. The determined anisotropic nature is used as a correction factor in a spectral analyzing system of flaw determination.

Multi-Wave Prospective Examination of the Stress-Reactivity Extension of Response Styles Theory of Depression in High-Risk Children and Early Adolescents

ERIC Educational Resources Information Center

Abela, John R. Z.; Hankin, Benjamin L.; Sheshko, Dana M.; Fishman, Michael B.; Stolow, Darren

2012-01-01

The current study tested the stress-reactivity extension of response styles theory of depression (Nolen-Hoeksema "Journal of Abnormal Psychology" 100:569-582, 1991) in a sample of high-risk children and early adolescents from a vulnerability-stress perspective using a multi-wave longitudinal design. In addition, we examined whether obtained…

An Overview of Findings from Wave 2 of the National Longitudinal Transition Study-2 (NLTS2). NCSER 2006-3004

ERIC Educational Resources Information Center

Wagner, Mary; Newman, Lynn; Cameto, Renee; Levine, Phyllis; Garza, Nicolle

2006-01-01

This report is an executive summary of two previously-released reports presenting findings from Wave 2: The Academic Achievement and Functional Performance of Youth with Disabilities and After High School: A First Look at the Postschool Experiences of Youth with Disabilities. Some key findings presented in the Overview include the following: (1) A…

Eating, feeding, and feeling: emotional responsiveness mediates longitudinal associations between maternal binge eating, feeding practices, and child weight.

PubMed

Saltzman, Jaclyn A; Pineros-Leano, Maria; Liechty, Janet M; Bost, Kelly K; Fiese, Barbara H

2016-08-02

Although it is known that maternal disordered eating is related to restrictive feeding practices, there is little research exploring mechanisms for this association or its effects on other feeding practices. The purpose of this study was to assess whether maternal emotion responses mediate the association between maternal binge eating (BE) and child feeding practices, in order to identify potential risk factors for feeding practices that influence child weight. This longitudinal observational study included (n = 260) mothers and children from the STRONG Kids Panel Survey. At Wave 1, children were an average of 37 months old (SD = 6.9), and at Wave 2 children were an average of 57 months old (SD = 8.3). Mothers self-reported their frequency of binge eating behavior (Wave 1), responses to children's negative emotions (Wave 1), feeding practices (Wave 1 and Wave 2), and child height and weight were measured at both time points. Using bias-corrected bootstrapping procedures, we tested the hypothesis that longitudinal associations between maternal BE and nonresponsive parent feeding practices would be mediated by parents' unsupportive responses to children's negative emotion. We also tested a serial mediation model positing that maternal BE predicts child body mass index (BMI) percentile change 18-24 months later, indirectly through unsupportive responses to negative emotion and nonresponsive feeding practices. Maternal BE predicted use of more nonresponsive feeding practices (e.g. Emotion Regulation, Restriction for Health, Pressure to Eat, and Food as Reward), indirectly through more Distress responses to children's negative emotions. In the serial mediation model, maternal BE was associated with greater use of Distress responses, which indirectly predicted higher child BMI percentile through Food as Reward feeding practices. These results suggest that maternal eating and emotion responsiveness are important for understanding the interpersonal context of feeding behaviors, and child weight outcomes. Distress responses may serve as a risk factor for use of unhealthful feeding practices among mothers with BE and these responses may increase children's risk for weight gain. This study used an observational prospective design. Therefore, it has not been registered as a clinical intervention trial.

Ultra-directional source of longitudinal acoustic waves based on a two-dimensional solid/solid phononic crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morvan, B.; Tinel, A.; Sainidou, R.

2014-12-07

Phononic crystals (PC) can be used to control the dispersion properties of acoustic waves, which are essential to direct their propagation. We use a PC-based two-dimensional solid/solid composite to demonstrate experimentally and theoretically the spatial filtering of a monochromatic non-directional wave source and its emission in a surrounding water medium as an ultra-directional beam with narrow angular distribution. The phenomenon relies on square-shaped equifrequency contours (EFC) enabling self-collimation of acoustic waves within the phononic crystal. Additionally, the angular width of collimated beams is controlled via the EFC size-shrinking when increasing frequency.

Longitudinal relationships between individual and class norms supporting dating violence and perpetration of dating violence.

PubMed

Taylor, Katherine A; Sullivan, Terri N; Farrell, Albert D

2015-03-01

Dating violence is commonly perpetrated in adolescence, making it imperative to understand risk factors in order to inform prevention efforts. Although individual norms supporting dating violence are strongly related to its perpetration, few studies have examined their longitudinal impact. Moreover, the influence of class norms (i.e., norms for students in the same grade, cohort, and school) supporting dating violence on perpetration has rarely been studied. The current study examined longitudinal relationships between individual and class norms supporting dating violence and perpetration of physical and psychological dating violence. Participants were two cohorts of sixth graders from 37 schools who were in dating relationships at Wave 1 and 6 months later at Wave 2 (N = 2,022; 43% female; 52% African American, 21% Latino/a, 20% White, and 7% other). The analyses used a multilevel approach, with students represented at Level 1 and classes (n = 74) at Level 2. The models tested direct effects of Wave 1 individual and class norms supporting dating violence on subsequent changes in perpetration of dating violence at Wave 2 and the extent to which gender moderated these relationships. The findings indicated that greater individual norms supporting male dating violence predicted greater change in perpetration of physical and psychological dating violence and greater individual norms supporting female dating violence predicted greater change in perpetration of psychological dating violence. Greater class norms supporting male dating violence predicted greater change in perpetration of physical dating violence; whereas greater class norms supporting female dating violence predicted less change in perpetration of physical dating violence. These findings highlight the need to address norms in early adolescence.

Stability and change in dietary scores and patterns across six waves of the Longitudinal Study of Australian Children.

PubMed

Gasser, Constantine E; Kerr, Jessica A; Mensah, Fiona K; Wake, Melissa

2017-04-01

This study aimed to derive and compare longitudinal trajectories of dietary scores and patterns from 2-3 to 10-11 years and from 4-5 to 14-15 years of age. In waves two to six of the Baby (B) Cohort and one to six of the Kindergarten (K) Cohort of the population-based Longitudinal Study of Australian Children, parents or children reported biennially on the study child's consumption of twelve to sixteen healthy and less healthy food or drink items for the previous 24 h. For each wave, we derived a dietary score from 0 to 14, based on the 2013 Australian Dietary Guidelines (higher scores indicating healthier diet). We then used factor analyses to empirically derive dietary patterns for separate waves. Using group-based trajectory modelling, we generated trajectories of dietary scores and empirical patterns in 4504 B and 4640 K Cohort children. Four similar trajectories of dietary scores emerged for the B and K Cohorts, containing comparable proportions of children in each cohort: 'never healthy' (8·8 and 11·9 %, respectively), 'moderately healthy' (24·0 and 20·7 %), 'becoming less healthy' (16·6 and 27·3 %) and 'always healthy' (50·7 and 40·2 %). Deriving trajectories based on dietary patterns, rather than dietary scores, produced similar findings. For 'becoming less healthy' trajectories, dietary quality appeared to worsen from 7 years of age in both cohorts. In conclusion, a brief dietary measure administered repeatedly across childhood generated robust, nuanced dietary trajectories that were replicable across two cohorts and two methodologies. These trajectories appear ideal for future research into dietary determinants and health outcomes.

Income inequality and depressive symptoms in South Africa: A longitudinal analysis of the National Income Dynamics Study.

PubMed

Adjaye-Gbewonyo, Kafui; Avendano, Mauricio; Subramanian, S V; Kawachi, Ichiro

2016-11-01

Research suggests that income inequality may detrimentally affect mental health. We examined the relationship between district-level income inequality and depressive symptoms among individuals in South Africa-one of the most unequal countries in the world-using longitudinal data from Wave 1 (2008) and Wave 3 (2012) of the National Income Dynamics Study. Depressive symptoms were measured using the Center for Epidemiological Studies of Depression Short Form while district Gini coefficients were estimated from census and survey sources. Age, African population group, being single, being female, and having lower household income were independently associated with higher depressive symptoms. However, in longitudinal, fixed-effects regression models controlling for several factors, district-level Gini coefficients were not significantly associated with depressive symptoms scores. Our results do not support the hypothesis of a causal link between income inequality and depressive symptoms in the short-run. Possible explanations include the high underlying levels of inequality in all districts, or potential lags in the effect of inequality on depression. Copyright © 2016 Elsevier Ltd. All rights reserved.

The reciprocal relationships among parents' expectations, adolescents' expectations, and adolescents' achievement: a two-wave longitudinal analysis of the NELS data.

PubMed

Zhang, Yanyan; Haddad, Eileen; Torres, Bernadeth; Chen, Chuansheng

2011-04-01

Previous research has consistently demonstrated the importance of parents' expectations and adolescents' expectations on adolescents' academic achievement. Less is known, however, about the reciprocal relationships among these constructs. To address this issue, we analyzed two waves of data from the National Education Longitudinal Study of 1988 (NELS:88) using longitudinal cross-lagged path models. The sample consisted of 14,376 students (51.1% females; 6.5% Asian, 11.1% Hispanic, 9.2% African American, and 73.2% White). Results indicated that there was a reciprocal relationship between parents' expectations and adolescents' expectations (i.e., they had mutual influence on each other). Moreover, there was a reciprocal relationship between expectations (both parents' and adolescents') and adolescents' academic achievement. Multiple-group analyses of gender and ethnicity revealed that the effects of parents' expectations on students' expectations were stronger among males than among females. With respect to ethnic differences, the effects of adolescents' expectations were weakest on parents' expectations among African Americans as compared to the other ethnic groups (i.e., Asian, Hispanic and White). Implications of these findings are discussed.

Reciprocal relations between workplace bullying, anxiety, and vigor: a two-wave longitudinal study.

PubMed

Rodríguez-Muñoz, Alfredo; Moreno-Jiménez, Bernardo; Sanz-Vergel, Ana Isabel

2015-01-01

Workplace bullying has been classified as an extreme social stressor in work contexts and has been repeatedly linked to several negative consequences. However, little research has examined reversed or reciprocal relations of bullying and outcomes. We conducted a two-wave longitudinal study with a time lag of six months. The study sample consisted of 348 employees of the Spanish workforce. The present study examined longitudinal relationships between workplace bullying, psychological health, and well-being. On the basis of conservation of resources theory, we hypothesized that we would find reciprocal relations among study variables over time. Results of cross-lagged structural equation modeling analyses supported our hypotheses. Specifically, it was found that Time 1 (T1) workplace bullying was negatively related to Time 2 (T2) vigor and positively related to T2 anxiety. Additionally, T1 anxiety and vigor had an effect on T2 workplace bullying. Overall, these findings support the validity of the theoretical models postulating a reciprocal bullying-outcome relationship, rather than simple one-way causal pathways approaches.

Perfectionistic concerns predict increases in adolescents' anxiety symptoms: a three-wave longitudinal study.

PubMed

Damian, Lavinia E; Negru-Subtirica, Oana; Stoeber, Joachim; Băban, Adriana

2017-09-01

Although perfectionism has been proposed to be a risk factor for the development of anxiety, research on perfectionism and anxiety symptoms in adolescents is scarce and inconclusive. The aim of the present study was to investigate whether the two higher-order dimensions of perfectionism - perfectionistic strivings and perfectionistic concerns - predict the development and maintenance of anxiety symptoms. An additional aim of the present study was to examine potential reciprocal effects of anxiety symptoms predicting increases in perfectionism. The study used a longitudinal design with three waves spaced 4-5 months apart. A non-clinical sample of 489 adolescents aged 12-19 years completed a paper-and-pencil questionnaire. As expected, results showed a positive effect from perfectionistic concerns to anxiety symptoms, but the effect was restricted to middle-to-late adolescents (16-19 years old): Perfectionistic concerns predicted longitudinal increases in adolescents' anxiety symptoms, whereas perfectionistic strivings did not. Furthermore, anxiety symptoms did not predict increases in perfectionism. Implications for the understanding of the relationship between perfectionism and anxiety symptoms are discussed.

A Six-Year Longitudinal Study of Consumption of Pornographic Materials in Chinese Adolescents in Hong Kong.

PubMed

Shek, Daniel T L; Ma, Cecilia M S

2016-02-01

Using longitudinal data collected over 6 years, consumption of pornographic materials in adolescents in Hong Kong and the related demographic and psychosocial correlates were examined in this study. DESIGN, SETTING, PARTICIPANTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: A longitudinal research design with 6 waves of data was used to examine consumption of pornographic materials in high school students. A total of 3291 high school students from 28 schools responded to the questionnaire at wave 1. Consumption of online pornography was higher than traditional pornography. There was an increase in consumption of pornographic materials in the high school years. Gender, family functioning, and positive youth development were related to the initial status of pornography consumption. Besides, gender, family intactness and positive youth development predicted rates of change in consumption of pornographic material over time. The present findings showed that gender, family functioning, and positive youth development are significant predictors for pornography consumption in Chinese adolescents. Copyright © 2016 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Numerical solution of equations governing longitudinal suspension line wave motion during the parachute unfurling process. Ph.D. Thesis - George Washington Univ., Washington, D. C.

NASA Technical Reports Server (NTRS)

Poole, L. R.

1973-01-01

Equations are presented which govern the dynamics of the lines-first parachute unfurling process, including wave motion in the parachute suspension lines. Techniques are developed for obtaining numerical solutions to the governing equations. Histories of tension at test data, and generally good agreement is observed. Errors in computed results are attributed to several areas of uncertainty, the most significant being a poorly defined boundary condition on the wave motion at the vehicle-suspension line boundary.

Effective-medium theory of elastic waves in random networks of rods.

PubMed

Katz, J I; Hoffman, J J; Conradi, M S; Miller, J G

2012-06-01

We formulate an effective medium (mean field) theory of a material consisting of randomly distributed nodes connected by straight slender rods, hinged at the nodes. Defining wavelength-dependent effective elastic moduli, we calculate both the static moduli and the dispersion relations of ultrasonic longitudinal and transverse elastic waves. At finite wave vector k the waves are dispersive, with phase and group velocities decreasing with increasing wave vector. These results are directly applicable to networks with empty pore space. They also describe the solid matrix in two-component (Biot) theories of fluid-filled porous media. We suggest the possibility of low density materials with higher ratios of stiffness and strength to density than those of foams, aerogels, or trabecular bone.

Nonlinear extraordinary wave in dense plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasovitskiy, V. B., E-mail: krasovit@mail.ru; Turikov, V. A.

2013-10-15

Conditions for the propagation of a slow extraordinary wave in dense magnetized plasma are found. A solution to the set of relativistic hydrodynamic equations and Maxwell’s equations under the plasma resonance conditions, when the phase velocity of the nonlinear wave is equal to the speed of light, is obtained. The deviation of the wave frequency from the resonance frequency is accompanied by nonlinear longitudinal-transverse oscillations. It is shown that, in this case, the solution to the set of self-consistent equations obtained by averaging the initial equations over the period of high-frequency oscillations has the form of an envelope soliton. Themore » possibility of excitation of a nonlinear wave in plasma by an external electromagnetic pulse is confirmed by numerical simulations.« less

Studies of thermal wave phenomena on the Jovian planets

NASA Technical Reports Server (NTRS)

Deming, Drake

1991-01-01

Ground-based and Voyager observations of Jupiter provided evidence that the tropospheric temperature shows global-scale longitudinal variations which are often wavelike in character. The investigation is presented which is directed toward obtaining additional ground-based data in IR spectral bands whose contribution functions are optimized for specific atmospheric regions, in order to confirm the previous results, and to identify the nature and physical significance of wavelike longitudinal temperature fluctuations on the Jovian planets.

Specifying the Role of Exposure to Violence and Violent Behavior on Initiation of Gun Carrying: A Longitudinal Test of Three Models of Youth Gun Carrying

ERIC Educational Resources Information Center

Spano, Richard; Pridemore, William Alex; Bolland, John

2012-01-01

Two waves of longitudinal data from 1,049 African American youth living in extreme poverty are used to examine the impact of exposure to violence (Time 1) and violent behavior (Time 1) on first time gun carrying (Time 2). Multivariate logistic regression results indicate that (a) violent behavior (Time 1) increased the likelihood of initiation of…

Longitudinal Plasmoid in High-Speed Vortex Gas Flow Created by Capacity HF Discharge

DTIC Science & Technology

2010-10-28

interferometer with high space resolution, PIV method, FTIR spectrometer, optical spectrometer, pressure sensors with high time resolution, IR pyrometer and...of strong LP-vortex interaction. Intensive acoustic waves are created by CHFD in swirl flow in this regime. 38. Study of control of a longitudinal...quartz tube, 4- HF ball electrode, 5- Tesla’s transformer, 6- microwave interferometer, 7- video camera, 8-optical pyrometer , 9-pressure sensor, 10

Characterisation of longitudinal variation in photonic crystal fibre

NASA Astrophysics Data System (ADS)

Francis-Jones, Robert J. A.; Mosley, Peter J.

2016-10-01

We present a method by which the degree of longitudinal variation in photonic crystal fibre (PCF) may be characterised through seeded four-wave mixing (FWM). Using an iterative numerical reconstruction, we created a model PCF that displays similar FWM phasematching properties across all measured length scales. Our results demonstrate that the structure of our PCF varies by less than 1% and that the characteristic length of the variations is approximately 15 cm.

Negatively valenced expectancy violation predicts emotionality: A longitudinal analysis.

PubMed

Bettencourt, B Ann; Manning, Mark

2016-09-01

We hypothesized that negatively valenced expectancy violations about the quality of 1's life would predict negative emotionality. We tested this hypothesis in a 4-wave longitudinal study of breast cancer survivors. The findings showed that higher levels of negatively valenced expectancy violation, at earlier time points, were associated with greater negative emotionality, at later time points. Implications of the findings are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

A Longitudinal Analysis of Stepfamily Relationship Quality and Adolescent Physical Health.

PubMed

Jensen, Todd M; Harris, Kathleen Mullan

2017-10-01

Approximately one third of youth are estimated to live with a biological parent and stepparent before reaching adulthood. Additional research is warranted whereby stepfamily processes are identified that drive variation in youth adjustment, particularly physical health. We examined stepfather-child, mother-child, and stepcouple relationship quality as predictors of levels and changes in adolescent physical health over time. We used a nationally representative sample of 1,233 adolescents living in biological mother-stepfather families from waves I (1994-1995) and II (1996) of the National Longitudinal Study of Adolescent to Adult Health. We incorporated measures of stepfather-child, mother-child, and stepcouple relationship quality, as well as adolescent reports of 10 physical health symptoms at waves I and II. Structural equation modeling was used to examine associations between wave I stepfamily relationships and adolescent physical symptoms at waves I and II. We used a zero-inflated negative binomial model to establish the validity of wave II adolescent physical symptoms as a predictor of an index of diagnosed chronic illnesses by wave IV (ages 26-32 years). Stepfather-child and mother-child relationship quality were negatively correlated with concurrent levels of adolescent physical symptoms. Stepfather-child relationship quality was negatively associated with change in adolescent physical symptoms over time. Adolescents with higher levels of physical symptoms at wave II were more likely to report chronic illnesses by adulthood. Stepfather-child relationship quality is a robust predictor of adolescent physical health throughout adolescence and is linked to chronic illness diagnoses in young adulthood. Future research should explore further the mechanisms that underlie this association. Copyright © 2017 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

The association of body mass index and externally perceived attractiveness across race/ethnicity, gender, and time.

PubMed

Richmond, Tracy K; Austin, S Bryn; Walls, Courtney E; Subramanian, S V

2012-01-01

Being perceived by others as unattractive is associated with negative health and social consequences. Overweight individuals may be more likely to be perceived by others as unattractive, thereby further endangering their well-being. Our objective was to determine whether body mass index (BMI) was associated with perceptions by others regarding attractiveness and whether this relationship was similar across race/ethnicity, gender, and time. We analyzed Waves I and III of the National Longitudinal Study of Adolescent Health, a nationally representative longitudinal study of adolescents. We used participant gender- and race/ethnicity-stratified multinomial logistic regression to examine the association between BMI and interviewer-rated attractiveness (1 = unattractive, 2 = average, 3 = attractive, 4 = very attractive) controlling for participant age, household income, and maternal education. BMI was positively associated with risk of being categorized as unattractive (relative to very attractive) by the interviewer in black (Wave I: relative risk ratio [RRR] = 1.26, CI: 1.18, 1.33; Wave III: RRR = 1.14, CI: 1.08, 1.20), Hispanic (Wave I: RRR = 1.23, CI: 1.11, 1.36; Wave III: RRR = 1.22, CI: 1.12, 1.34), and white (Wave I: RRR = 1.25, CI: 1.19, 1.32; Wave III: RRR = 1.22, CI: 1.17, 1.28) females in both waves of data collection. Only in African American females, the risk of being rated unattractive with increasing BMI declined significantly between waves (p = .00018). Trends were similar in males, although the magnitude of risk was smaller and nonsignificant in most groups. Interviewers were more likely to rate those with higher BMIs as unattractive; this finding was similar across gender and racial/ethnic groups with few exceptions and was stable across time. Copyright © 2012 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Connection between the two branches of the quantum two-stream instability across the k space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bret, A.; Haas, F.

2010-05-15

The stability of two quantum counterstreaming electron beams is investigated within the quantum plasma fluid equations for arbitrarily oriented wave vectors k. The analysis reveals that the two quantum two-stream unstable branches are indeed connected by a continuum of unstable modes with oblique wave vectors. Using the longitudinal approximation, the stability domain for any k is analytically explained, together with the growth rate.

A stress wave based approach to NDE of logs for assessing potential veneer quality: Part I—small-diameter ponderosa pine.

Treesearch

Robert J. Ross; Susan W. Willits; William Von Segen; Terry Black; Brian K. Brashaw; Roy F. Pellerin

1999-01-01

Longitudinal stress wave nondestructive evaluation (NDE) techniques have been used in a variety of applications in the forest products industry. Recently, it has been shown that they can significantly aid in the assessment of log quality, particularly when they are used to predict performance of structural lumber obtained from a log. The purpose of the research...

Wave fluctuations in the system with some Yang-Mills condensates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prokhorov, G., E-mail: zhoraprox@yandex.ru; Pasechnik, R., E-mail: Roman.Pasechnik@thep.lu.se; Vereshkov, G., E-mail: gveresh@gmail.com

2016-12-15

Self-consistent dynamics of non-homogeneous fluctuations and homogeneous and isotropic condensate of Yang–Mills fields was investigated in zero, linear and quasilinear approximations over the wave modes in the framework of N = 4 supersymmetric model in Hamilton gauge in quasiclassical theory. The models with SU(2), SU(3) and SU(4) gauge groups were considered. Particle production effect and effect of generation of longitudinal oscillations were obtained.

Personality Types in Adolescence: Change and Stability and Links with Adjustment and Relationships--A Five-Wave Longitudinal Study

ERIC Educational Resources Information Center

Meeus, Wim; Van de Schoot, Rens; Klimstra, Theo; Branje, Susan

2011-01-01

We examined change and stability of the 3 personality types identified by Block and Block (1980) and studied their links with adjustment and relationships. We used data from a 5-wave study of 923 early-to-middle and 390 middle-to-late adolescents, thereby covering the ages of 12-20 years. In Study 1, systematic evidence for personality change was…

On the Progression and Stability of Adolescent Identity Formation: A Five-Wave Longitudinal Study in Early-to-Middle and Middle-to-Late Adolescence

ERIC Educational Resources Information Center

Meeus, Wim; Van De Schoot, Rens; Keijsers, Loes; Schwartz, Seth J.; Branje, Susan

2010-01-01

This study examined identity development in a 5-wave study of 923 early-to-middle and 390 middle-to-late adolescents thereby covering the ages of 12-20. Systematic evidence for identity progression was found: The number of diffusions, moratoriums, and searching moratoriums (a newly obtained status) decreased, whereas the representation of the…

Family Transitions in Cohabiting Families: a Longitudinal Investigation of the Role of Parent Depressive Symptoms in Youth Problem Behaviors.

PubMed

Parent, Justin; Peisch, Virginia D; Forehand, Rex; Golub, Andrew; Reid, Megan

2017-05-01

Cohabiting family structures are becoming increasingly prevalent in the United States but are less stable than married family unions. In this longitudinal study we examine the change in psychosocial adjustment of adolescents when a non-biologically related male cohabiting partner (MCP) transitions out of the family home. Of particular interest, the role of maternal and MCP depressive symptoms was examined as a moderator. At wave 1, the sample was comprised of 111 low-income urban Black families, consisting of an adolescent (42.3 % male; Mage = 13), a biological mother, and a non-biologically-related male cohabiting partner (MCP). Wave 2 and 3 assessments occurred over the course of the subsequent 29 months, with 38 % of MCPs transitioning out of the home. We used latent growth curve modeling to characterize trajectories of youth internalizing and externalizing symptom change across the 3 waves. Both maternal and MCP depressive symptoms interacted with whether a transition occurred, consistent with the notion that adolescent problem behaviors are shaped by the dynamic interplay of individual- and family-characteristics.

A bidirectional relationship between physical activity and executive function in older adults

PubMed Central

Daly, Michael; McMinn, David; Allan, Julia L.

2015-01-01

Physically active lifestyles contribute to better executive function. However, it is unclear whether high levels of executive function lead people to be more active. This study uses a large sample and multi-wave data to identify whether a reciprocal association exists between physical activity and executive function. Participants were 4555 older adults tracked across four waves of the English Longitudinal Study of Aging. In each wave executive function was assessed using a verbal fluency test and a letter cancelation task and participants reported their physical activity levels. Fixed effects regressions showed that changes in executive function corresponded with changes in physical activity. In longitudinal multilevel models low levels of physical activity led to subsequent declines in executive function. Importantly, poor executive function predicted reductions in physical activity over time. This association was found to be over 50% larger in magnitude than the contribution of physical activity to changes in executive function. This is the first study to identify evidence for a robust bidirectional link between executive function and physical activity in a large sample of older adults tracked over time. PMID:25628552

Stepfamily Relationship Quality and Children's Internalizing and Externalizing Problems.

PubMed

Jensen, Todd M; Lippold, Melissa A; Mills-Koonce, Roger; Fosco, Gregory M

2017-03-07

The stepfamily literature is replete with between-group analyses by which youth residing in stepfamilies are compared to youth in other family structures across indicators of adjustment and well-being. Few longitudinal studies examine variation in stepfamily functioning to identify factors that promote the positive adjustment of stepchildren over time. Using a longitudinal sample of 191 stepchildren (56% female, mean age = 11.3 years), the current study examines the association between the relationship quality of three central stepfamily dyads (stepparent-child, parent-child, and stepcouple) and children's internalizing and externalizing problems concurrently and over time. Results from path analyses indicate that higher levels of parent-child affective quality are associated with lower levels of children's concurrent internalizing and externalizing problems at Wave 1. Higher levels of stepparent-child affective quality are associated with decreases in children's internalizing and externalizing problems at Wave 2 (6 months beyond baseline), even after controlling for children's internalizing and externalizing problems at Wave 1 and other covariates. The stepcouple relationship was not directly linked to youth outcomes. Our findings provide implications for future research and practice. © 2017 Family Process Institute.

Family Transitions in Cohabiting Families: A Longitudinal Investigation of the Role of Parent Depressive Symptoms in Youth Problem Behaviors

PubMed Central

Parent, Justin; Peisch, Virginia D.; Forehand, Rex; Golub, Andrew; Reid, Megan

2018-01-01

Cohabiting family structures are becoming increasingly prevalent in the United States but are less stable than married family unions. In this longitudinal study we examine the change in psychosocial adjustment of adolescents when a non-biologically related male cohabiting partner (MCP) transitions out of the family home. Of particular interest, the role of maternal and MCP depressive symptoms was examined as a moderator. At wave 1, the sample was comprised of 111 low-income urban Black families, consisting of an adolescent (42.3% male; Mage= 13), a biological mother, and a non-biologically-related male cohabiting partner (MCP). Wave 2 and 3 assessments occurred over the course of the subsequent 29 months, with 38% of MCPs transitioning out of the home. We used latent growth curve modeling to characterize trajectories of youth internalizing and externalizing symptom change across the 3 waves. Both maternal and MCP depressive symptoms interacted with whether a transition occurred, consistent with the notion that adolescent problem behaviors are shaped by the dynamic interplay of individual- and family-characteristics. PMID:27581704

3.5 GHz longitudinal leaky surface acoustic wave resonator using a multilayered waveguide structure for high acoustic energy confinement

NASA Astrophysics Data System (ADS)

Kimura, Tetsuya; Kishimoto, Yutaka; Omura, Masashi; Hashimoto, Ken-ya

2018-07-01

In this paper, the use of a structure comprising a thin LiNbO3 plate and a multilayered acoustic mirror composed of SiO2 and Pt for high-performance longitudinal leaky surface acoustic wave (LLSAW) device is proposed. The mirror is expected to offer a much higher reflectivity than that composed of SiO2 and AlN, which the authors proposed previously. The field distribution of these structures is calculated by using a finite element method. It is shown that the acoustic wave energy of the proposed structure is well confined in the vicinity of the top surface, and that leakage to the substrate is reduced. A one-port resonator is fabricated on the structure and its performance characteristics are evaluated. Owing to a high phase velocity of 6,035 m/s, which is about 1.5 times higher than that of conventional SAWs, a large impedance ratio of 71 dB was achieved at 3.5 GHz in addition to a large fractional bandwidth of 9.5%.

RF power absorption by plasma of low pressure low power inductive discharge located in the external magnetic field

NASA Astrophysics Data System (ADS)

Kralkina, E. A.; Rukhadze, A. A.; Nekliudova, P. A.; Pavlov, V. B.; Petrov, A. K.; Vavilin, K. V.

2018-03-01

Present paper is aimed to reveal experimentally and theoretically the influence of magnetic field strength, antenna shape, pressure, operating frequency and geometrical size of plasma sources on the ability of plasma to absorb the RF power characterized by the equivalent plasma resistance for the case of low pressure RF inductive discharge located in the external magnetic field. The distinguishing feature of the present paper is the consideration of the antennas that generate not only current but charge on the external surface of plasma sources. It is shown that in the limited plasma source two linked waves can be excited. In case of antennas generating only azimuthal current the waves can be attributed as helicon and TG waves. In the case of an antenna with the longitudinal current there is a surface charge on the side surface of the plasma source, which gives rise to a significant increase of the longitudinal and radial components of the RF electric field as compared with the case of the azimuthal antenna current.

Association between interpersonal trust, reciprocity, and suicidal behaviors: A longitudinal cohort study in South Korea.

PubMed

Kim, Ja Young; Yoon, Jaehong; Kim, Myoung-Hee; Kim, Seung-Sup

2017-06-01

While a growing body of evidence suggest that social capital including interpersonal trust and reciprocity might be associated with mental health outcomes, few studies have explored the relationship with suicidal behaviors. This research examined the prospective association between interpersonal trust and reciprocity and suicidal behaviors using the Korea Welfare Panel Study, a nationally representative longitudinal cohort dataset in South Korea. Interpersonal trust and reciprocity were assessed at the 7th wave of the survey (2012), and each measure was classified into two categories (low vs. high). Experience of suicidal ideation, planning, and attempt was assessed between the 8th (2013) and 10th wave (2015) of the surveys. After adjusting for confounders including lifetime experience of suicidal behaviors at the 7th wave of the survey (2012) as well as socio-demographic information, the low interpersonal trust group was more likely to experience suicidal ideation (OR: 1.30, 95% CI: 1.11-1.53) compared to the high interpersonal trust group whereas no statistically significant association was observed in the reciprocity analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

Data Resource Profile: Cross-national and cross-study sociodemographic and health-related harmonized domains from SAGE plus ELSA, HRS and SHARE (SAGE+, Wave 1)

PubMed Central

Minicuci, Nadia; Naidoo, Nirmala; Chatterji, Somnath; Kowal, Paul

2016-01-01

Four longitudinal studies were included in this rigorous harmonization process: the Study on global AGEing and adult health (SAGE); English Longitudinal Study on Ageing (ELSA); US Health and Retirement Study (HRS); and Survey of Health, Ageing and Retirement in Europe (SHARE). An ex-post harmonized process was applied to nine health-related thematic domains (socio-demographic and economic, health states, overall self-report of health and mental state, health examinations, physical and mental performance tests, risk factors, chronic conditions, social network and subjective well-being) for data from the 2004 wave of each study. Large samples of adults aged 50 years and older were available from each study: SAGE, n = 18 886; ELSA, n = 9181; HRS, n = 19 303; and SHARE, n = 29 917. The microdata, along with further details about the harmonization process and all metadata, are available through the World Health Organization (WHO) data archive at [http://apps.who.int/healthinfo/systems/surveydata/index.php/catalog]. Further information and enquiries can be made to [sagesurvey@who.int] or the corresponding author. The data resource will continue to be updated with data across additional waves of these surveys and new waves. PMID:27794522

Vorticity Transfer in Shock Wave Interactions with Turbulence and Vortices

NASA Astrophysics Data System (ADS)

Agui, J. H.; Andreopoulos, J.

1998-11-01

Time-dependent, three-dimensional vorticity measurements of shock waves interacting with grid generated turbulence and concentrated tip vortices were conducted in a large diameter shock tube facility. Two different mesh size grids and a NACA-0012 semi-span wing acting as a tip vortex generator were used to carry out different relative Mach number interactions. The turbulence interactions produced a clear amplification of the lateral and spanwise vorticity rms, while the longitudinal component remained mostly unaffected. By comparison, the tip vortex/shock wave interactions produced a two fold increase in the rms of longitudinal vorticity. Considerable attention was given to the vorticity source terms. The mean and rms of the vorticity stretching terms dominated by 5 to 7 orders of magnitude over the dilitational compression terms in all the interactions. All three signals of the stretching terms manifested very intermittent, large amplitude peak events which indicated the bursting character of the stretching process. Distributions of these signals were characterized by extremely large levels of flatness with varying degrees of skewness. These distribution patterns were found to change only slightly through the turbulence interactions. However, the tip vortex/shock wave interactions brought about significant changes in these distributions which were associated with the abrupt structural changes of the vortex after the interaction.

Sound pressure distribution within natural and artificial human ear canals: Forward stimulation

PubMed Central

Ravicz, Michael E.; Tao Cheng, Jeffrey; Rosowski, John J.

2014-01-01

This work is part of a study of the interaction of sound pressure in the ear canal (EC) with tympanic membrane (TM) surface displacement. Sound pressures were measured with 0.5–2 mm spacing at three locations within the shortened natural EC or an artificial EC in human temporal bones: near the TM surface, within the tympanic ring plane, and in a plane transverse to the long axis of the EC. Sound pressure was also measured at 2-mm intervals along the long EC axis. The sound field is described well by the size and direction of planar sound pressure gradients, the location and orientation of standing-wave nodal lines, and the location of longitudinal standing waves along the EC axis. Standing-wave nodal lines perpendicular to the long EC axis are present on the TM surface >11–16 kHz in the natural or artificial EC. The range of sound pressures was larger in the tympanic ring plane than at the TM surface or in the transverse EC plane. Longitudinal standing-wave patterns were stretched. The tympanic-ring sound field is a useful approximation of the TM sound field, and the artificial EC approximates the natural EC. PMID:25480061

The relationship between elastic constants and structure of shock waves in a zinc single crystal

NASA Astrophysics Data System (ADS)

Krivosheina, M. N.; Kobenko, S. V.; Tuch, E. V.

2017-12-01

The paper provides a 3D finite element simulation of shock-loaded anisotropic single crystals on the example of a Zn plate under impact using a mathematical model, which allows for anisotropy in hydrostatic stress and wave velocities in elastic and plastic ranges. The simulation results agree with experimental data, showing the absence of shock wave splitting into an elastic precursor and a plastic wave in Zn single crystals impacted in the [0001] direction. It is assumed that the absence of an elastic precursor under impact loading of a zinc single crystal along the [0001] direction is determined by the anomalously large ratio of the c/a-axes and close values of the propagation velocities of longitudinal and bulk elastic waves. It is shown that an increase in only one elastic constant along the [0001] direction results in shock wave splitting into an elastic precursor and a shock wave of "plastic" compression.

Negative refraction of elastic waves at the deep-subwavelength scale in a single-phase metamaterial.

PubMed

Zhu, R; Liu, X N; Hu, G K; Sun, C T; Huang, G L

2014-11-24

Negative refraction of elastic waves has been studied and experimentally demonstrated in three- and two-dimensional phononic crystals, but Bragg scattering is impractical for low-frequency wave control because of the need to scale the structures to manageable sizes. Here we present an elastic metamaterial with chiral microstructure made of a single-phase solid material that aims to achieve subwavelength negative refraction of elastic waves. Both negative effective mass density and modulus are observed owing to simultaneous translational and rotational resonances. We experimentally demonstrate negative refraction of the longitudinal elastic wave at the deep-subwavelength scale in the metamaterial fabricated in a stainless steel plate. The experimental measurements are in good agreement with numerical simulations. Moreover, wave mode conversion related with negative refraction is revealed and discussed. The proposed elastic metamaterial may thus be used as a flat lens for elastic wave focusing.

Lateralization of Travelling Wave Response in the Hearing Organ of Bushcrickets

PubMed Central

Palghat Udayashankar, Arun; Kössl, Manfred; Nowotny, Manuela

2014-01-01

Travelling waves are the physical basis of frequency discrimination in many vertebrate and invertebrate taxa, including mammals, birds, and some insects. In bushcrickets (Tettigoniidae), the crista acustica is the hearing organ that has been shown to use sound-induced travelling waves. Up to now, data on mechanical characteristics of sound-induced travelling waves were only available along the longitudinal (proximal-distal) direction. In this study, we use laser Doppler vibrometry to investigate in-vivo radial (anterior-posterior) features of travelling waves in the tropical bushcricket Mecopoda elongata. Our results demonstrate that the maximum of sound-induced travelling wave amplitude response is always shifted towards the anterior part of the crista acustica. This lateralization of the travelling wave response induces a tilt in the motion of the crista acustica, which presumably optimizes sensory transduction by exerting a shear motion on the sensory cilia in this hearing organ. PMID:24465889

Parenting and Adolescent Self-Regulation Mediate between Family Socioeconomic Status and Adolescent Adjustment

PubMed Central

Farley, Julee P.; Kim-Spoon, Jungmeen

2016-01-01

Using two waves of longitudinal data, we utilized the family stress model of economic hardship (Conger & Conger, 2002) to test whether family socioeconomic status is related to adolescent adjustment (substance use and academic achievement) through parental knowledge and adolescent self-regulation (behavioral self-control and delay discounting). Participants included 220 adolescent (55% male, mean age = 13 years at Wave 1, mean age = 15 years at Wave 2) and primary caregiver dyads. Results of Structural Equation Modeling revealed significant three-path mediation effects such that low family socioeconomic status at Wave 1 is associated with low parental knowledge at Wave 1, which in turn was related to low academic performance and high substance use at Wave 2 mediated through low adolescent behavioral self-control at Wave 2. The results illustrate how parental knowledge, influenced by family economic status, may play an important role in the development of adolescent behavioral self-control and adjustment. PMID:28348448

Internet use and cancer-preventive behaviors in older adults: findings from a longitudinal cohort study.

PubMed

Xavier, Andre Junqueira; d'Orsi, Eleonora; Wardle, Jane; Demakakos, Panayotes; Smith, Samuel G; von Wagner, Christian

2013-11-01

The Internet is a key provider of health information, but little is known about its associations with cancer-preventive behaviors. This study investigated the associations between Internet use and cancer-preventive behaviors among older adults. Data were taken from Waves 1 to 5 (2002-2011) of the English Longitudinal Study of Aging, a cohort study of men and women 50 years or older in England, United Kingdom. Internet use was recorded at each wave. Breast and colorectal screening, fruit and vegetable consumption, physical activity, and smoking were recorded at Wave 5. Social, cognitive, and physical function variables recorded at Wave 1 were analyzed as predictors of Internet use and included as covariates in analyses linking Internet use to behavior. Of 5,943 respondents, 41.4% did not report any Internet use, 38.3% reported using it in one to three waves ("intermittent users"), and 20.3% used it in all waves ("consistent users"). Internet use was higher in younger, male, White, wealthier, more educated respondents, and those without physical limitations. Multivariable analysis showed that consistent users were more likely than "never users" to report CRC screening, weekly moderate/vigorous physical activity, and five or more daily servings of fruit and vegetables, and less likely to report smoking. There was no significant association between Internet use and breast screening. Internet use showed a quantitative association with cancer-preventive behaviors even after controlling for various social, cognitive, and physical correlates of Internet use. Promoting Internet use among older adults from all backgrounds could contribute to improving cancer outcomes and reducing inequalities. ©2013 AACR.

Reasons for Trying E-cigarettes and Risk of Continued Use

PubMed Central

Kong, Grace; Cavallo, Dana A.; Camenga, Deepa R.; Krishnan-Sarin, Suchitra

2016-01-01

BACKGROUND: Longitudinal research is needed to identify predictors of continued electronic cigarette (e-cigarette) use among youth. We expected that certain reasons for first trying e-cigarettes would predict continued use over time (eg, good flavors, friends use), whereas other reasons would not predict continued use (eg, curiosity). METHODS: Longitudinal surveys from middle and high school students from fall 2013 (wave 1) and spring 2014 (wave 2) were used to examine reasons for trying e-cigarettes as predictors of continued e-cigarette use over time. Ever e-cigarette users (n = 340) at wave 1 were categorized into those using or not using e-cigarettes at wave 2. Among those who continued using e-cigarettes, reasons for trying e-cigarettes were examined as predictors of use frequency, measured as the number of days using e-cigarettes in the past 30 days at wave 2. Covariates included age, sex, race, and smoking of traditional cigarettes. RESULTS: Several reasons for first trying e-cigarettes predicted continued use, including low cost, the ability to use e-cigarettes anywhere, and to quit smoking regular cigarettes. Trying e-cigarettes because of low cost also predicted more days of e-cigarette use at wave 2. Being younger or a current smoker of traditional cigarettes also predicted continued use and more frequent use over time. CONCLUSIONS: Regulatory strategies such as increasing cost or prohibiting e-cigarette use in certain places may be important for preventing continued use in youth. In addition, interventions targeting current cigarette smokers and younger students may also be needed. PMID:27503349

Reasons for Trying E-cigarettes and Risk of Continued Use.

PubMed

Bold, Krysten W; Kong, Grace; Cavallo, Dana A; Camenga, Deepa R; Krishnan-Sarin, Suchitra

2016-09-01

Longitudinal research is needed to identify predictors of continued electronic cigarette (e-cigarette) use among youth. We expected that certain reasons for first trying e-cigarettes would predict continued use over time (eg, good flavors, friends use), whereas other reasons would not predict continued use (eg, curiosity). Longitudinal surveys from middle and high school students from fall 2013 (wave 1) and spring 2014 (wave 2) were used to examine reasons for trying e-cigarettes as predictors of continued e-cigarette use over time. Ever e-cigarette users (n = 340) at wave 1 were categorized into those using or not using e-cigarettes at wave 2. Among those who continued using e-cigarettes, reasons for trying e-cigarettes were examined as predictors of use frequency, measured as the number of days using e-cigarettes in the past 30 days at wave 2. Covariates included age, sex, race, and smoking of traditional cigarettes. Several reasons for first trying e-cigarettes predicted continued use, including low cost, the ability to use e-cigarettes anywhere, and to quit smoking regular cigarettes. Trying e-cigarettes because of low cost also predicted more days of e-cigarette use at wave 2. Being younger or a current smoker of traditional cigarettes also predicted continued use and more frequent use over time. Regulatory strategies such as increasing cost or prohibiting e-cigarette use in certain places may be important for preventing continued use in youth. In addition, interventions targeting current cigarette smokers and younger students may also be needed. Copyright © 2016 by the American Academy of Pediatrics.

Flowing together: a longitudinal study of collective efficacy and collective flow among workgroups.

PubMed

Salanova, Marisa; Rodríguez-Sánchez, Alma M; Schaufeli, Wilmar B; Cifre, Eva

2014-01-01

The aim of this study is to extend the Channel Model of Flow (Csikszentmihalyi, 1975, 1990) at the collective level (workgroups) by including collective efficacy beliefs as a predictor of collective flow based on the Social Cognitive Theory (Bandura, 1997, 2001). A two-wave longitudinal lab study was conducted with 250 participants working in 52 small groups. Longitudinal results from Structural Equation Modeling with data aggregated at the group level showed, as expected, that collective efficacy beliefs predict collective flow over time, both being related reciprocally. Findings and their theoretical and practical implications in the light of Social Cognitive Theory are discussed.

Charge creation and nucleation of the longitudinal plasma wave in coupled Josephson junctions

NASA Astrophysics Data System (ADS)

Shukrinov, Yu. M.; Hamdipour, M.

2010-11-01

We study the phase dynamics in coupled Josephson junctions described by a system of nonlinear differential equations. Results of detailed numerical simulations of charge creation in the superconducting layers and the longitudinal plasma wave (LPW) nucleation are presented. We demonstrate the different time stages in the development of the LPW and present the results of FFT analysis at different values of bias current. The correspondence between the breakpoint position on the outermost branch of current voltage characteristics (CVC) and the growing region in time dependence of the electric charge in the superconducting layer is established. The effects of noise in the bias current and the external microwave radiation on the charge dynamics of the coupled Josephson junctions are found. These effects introduce a way to regulate the process of LPW nucleation in the stack of IJJ.

Room temperature quarter wave resonator re-buncher development for a high power heavy-ion linear accelerator

NASA Astrophysics Data System (ADS)

Kim, Hye-Jin; Choi, B. H.; Han, Jaeeun; Hyun, Myung Ook; Park, Bum-Sik; Choi, Ohryoung; Lee, Doyoon; Son, Kitaek

2018-03-01

In the medium energy beam transport (MEBT) line system of the RAON which consists of several quadrupole magnets, three normal-conducting re-bunchers, and several diagnostic devices, a quarter wave resonator type re-buncher was chosen for minimizing longitudinal emittance growth and manipulating a longitudinal phase ellipse into the longitudinal acceptance of the low energy linac. The re-buncher has a resonant frequency of 81.25 MHz, geometrical beta (βg) of 0.049, and physical length of 24 cm. Based on the result of numerical calculations of electromagnetic field using CST-MWS and mechanical analysis of the heat distribution and deformation, an internal structure of the re-buncher was optimized to increase the effective voltage and to reduce power losses in the wall. The criteria of the multipacting effect was estimated and it was confirmed by the experiment. The position and specification of cooling channels are designed to recover a heat load up to 15 kW with reasonable margin of 25%. The coaxial and loop type RF power coupler are positioned on the high magnetic field region and two slug tuners are installed perpendicularly to the beam axis. The frequency sensitivity as a function of the tuner depth and cooling water temperature is measured and the frequency shift is in all cases within the provided tuner range. The test with a high power of 10 kW and the continuous wave is performed and the reflection power is observed less than 450 W.

Spatiotemporal mode-locking in multimode fiber lasers

NASA Astrophysics Data System (ADS)

Wright, Logan G.; Christodoulides, Demetrios N.; Wise, Frank W.

2017-10-01

A laser is based on the electromagnetic modes of its resonator, which provides the feedback required for oscillation. Enormous progress has been made toward controlling the interactions of longitudinal modes in lasers with a single transverse mode. For example, the field of ultrafast science has been built on lasers that lock many longitudinal modes together to form ultrashort light pulses. However, coherent superposition of longitudinal and transverse modes in a laser has received little attention. We show that modal and chromatic dispersions in fiber lasers can be counteracted by strong spatial and spectral filtering. This allows locking of multiple transverse and longitudinal modes to create ultrashort pulses with a variety of spatiotemporal profiles. Multimode fiber lasers thus open new directions in studies of nonlinear wave propagation and capabilities for applications.

Political Violence and Child Adjustment: Longitudinal Tests of Sectarian Antisocial Behavior, Family Conflict and Insecurity as Explanatory Pathways

PubMed Central

Cummings, E. Mark; Merrilees, Christine E.; Schermerhorn, Alice C.; Goeke-Morey, Marcie C.; Shirlow, Peter; Cairns, Ed

2011-01-01

Understanding the impact of political violence on child maladjustment is a matter of international concern. Recent research has advanced a social ecological explanation for relations between political violence and child adjustment. However, conclusions are qualified by the lack of longitudinal tests. Towards examining pathways longitudinally, mothers and their adolescents (M = 12.33, SD =1.78, at time 1) from two-parent families in Catholic and Protestant working class neighborhoods in Belfast, Northern Ireland, completed measures assessing multiple levels of a social ecological model. Utilizing autoregressive controls, a three-wave longitudinal model test (T1, n = 299; T2, n = 248; T3, n = 197) supported a specific pathway linking sectarian community violence, family conflict, children’s insecurity about family relationships, and adjustment problems. PMID:22313052

Numerical study on static component generation from the primary Lamb waves propagating in a plate with nonlinearity

NASA Astrophysics Data System (ADS)

Wan, Xiang; Tse, Peter W.; Zhang, Xuhui; Xu, Guanghua; Zhang, Qing; Fan, Hongwei; Mao, Qinghua; Dong, Ming; Wang, Chuanwei; Ma, Hongwei

2018-04-01

Under the discipline of nonlinear ultrasonics, in addition to second harmonic generation, static component generation is another frequently used nonlinear ultrasonic behavior in non-destructive testing (NDT) and structural health monitoring (SHM) communities. However, most previous studies on static component generation are mainly based on using longitudinal waves. It is desirable to extend static component generation from primary longitudinal waves to primary Lamb waves. In this paper, static component generation from the primary Lamb waves is studied. Two major issues are numerically investigated. First, the mode of static displacement component generated from different primary Lamb wave modes is identified. Second, cumulative effect of static displacement component from different primary Lamb wave modes is also discussed. Our study results show that the static component wave packets generated from the primary S0, A0 and S1 modes share the almost same group velocity equal to the phase velocity of S0 mode tending to zero frequency c plate . The finding indicates that whether the primary mode is S0, A0 or S1, the static components generated from these primary modes always share the nature of S0 mode. This conclusion is also verified by the displacement filed of these static components that the horizontal displacement field is almost uniform and the vertical displacement filed is antisymmetric across the thickness of the plate. The uniform distribution of horizontal displacement filed enables the static component, regardless of the primary Lamb modes, to be a promising technique for evaluating microstructural damages buried in the interior of a structure. Our study also illustrates that the static components are cumulative regardless of whether the phase velocity of the primary and secondary waves is matched or not. This observation indicates that the static component overcomes the limitations of the traditional nonlinear Lamb waves satisfying phase velocity matching condition to achieve cumulative second harmonic generation. This nature also enables the primary Lamb waves excited at a low center frequency to generate static component used for inspecting large-scale structures with micro-scale damages.

Wave scattering in spatially inhomogeneous currents

NASA Astrophysics Data System (ADS)

Churilov, Semyon; Ermakov, Andrei; Stepanyants, Yury

2017-09-01

We analytically study a scattering of long linear surface waves on stationary currents in a duct (canal) of constant depth and variable width. It is assumed that the background velocity linearly increases or decreases with the longitudinal coordinate due to the gradual variation of duct width. Such a model admits an analytical solution of the problem in hand, and we calculate the scattering coefficients as functions of incident wave frequency for all possible cases of sub-, super-, and transcritical currents. For completeness we study both cocurrent and countercurrent wave propagation in accelerating and decelerating currents. The results obtained are analyzed in application to recent analog gravity experiments and shed light on the problem of hydrodynamic modeling of Hawking radiation.

A TE-mode accelerator

NASA Astrophysics Data System (ADS)

Takeuchi, S.; Sakai, K.; Matsumoto, M.; Sugihara, R.

1987-04-01

An accelerator is proposed in which a TE-mode wave is used to drive charged particles in contrast to the usual linear accelerators in which longitudinal electric fields or TM-mode waves are supposed to be utilized. The principle of the acceleration is based on the V(p) x B acceleration of a dynamo force acceleration, in which a charged particle trapped in a transverse wave feels a constant electric field (Faraday induction field) and subsequently is accelerated when an appropriate magnetic field is externally applied in the direction perpendicular to the wave propagation. A pair of dielectric plates is used to produce a slow TE mode. The conditions of the particle trapping the stabilization of the particle orbit are discussed.

Radiative corrections to the Coulomb law and model of dense quantum plasmas: Dispersion of longitudinal waves in magnetized quantum plasmas

NASA Astrophysics Data System (ADS)

Andreev, Pavel A.

2018-04-01

Two kinds of quantum electrodynamic radiative corrections to electromagnetic interactions and their influence on the properties of highly dense quantum plasmas are considered. Linear radiative correction to the Coulomb interaction is considered. Its contribution in the spectrum of the Langmuir waves is presented. The second kind of radiative corrections are related to the nonlinearity of the Maxwell equations for the strong electromagnetic field. Their contribution in the spectrum of transverse waves of magnetized plasmas is briefly discussed. At the consideration of the Langmuir wave spectrum, we included the effect of different distributions of the spin-up and spin-down electrons revealing in the Fermi pressure shift.

Correlation of Fiber Composite Tensile Strength with the Ultrasonic Stress Wave Factor

NASA Technical Reports Server (NTRS)

Vary, A.; Lark, R. F.

1978-01-01

An ultrasonic-acoustic technique was used to indicate the strength variations of tensile specimens of a graphite-epoxy composite. A stress wave factor was determined and its value was found to depend on variations of the fiber-resin bonding as well as fiber orientation. The fiber orientations studied were 0 deg (longitudinal), 10 deg (off-axis), 90 deg (transverse), 0 deg + or - 45 deg/0 deg symmetrical, and + or - 45 deg] symmetrical. The stress wave factor can indicate variations of the tensile and shear strengths of composite materials. The stress wave factor was also found to be sensitive to strength variations associated with microporosity and differences in fiber-resin ratio.

Numerical and experimental study on the wave attenuation in bone--FDTD simulation of ultrasound propagation in cancellous bone.

PubMed

Nagatani, Yoshiki; Mizuno, Katsunori; Saeki, Takashi; Matsukawa, Mami; Sakaguchi, Takefumi; Hosoi, Hiroshi

2008-11-01

In cancellous bone, longitudinal waves often separate into fast and slow waves depending on the alignment of bone trabeculae in the propagation path. This interesting phenomenon becomes an effective tool for the diagnosis of osteoporosis because wave propagation behavior depends on the bone structure. Since the fast wave mainly propagates in trabeculae, this wave is considered to reflect the structure of trabeculae. For a new diagnosis method using the information of this fast wave, therefore, it is necessary to understand the generation mechanism and propagation behavior precisely. In this study, the generation process of fast wave was examined by numerical simulations using elastic finite-difference time-domain (FDTD) method and experimental measurements. As simulation models, three-dimensional X-ray computer tomography (CT) data of actual bone samples were used. Simulation and experimental results showed that the attenuation of fast wave was always higher in the early state of propagation, and they gradually decreased as the wave propagated in bone. This phenomenon is supposed to come from the complicated propagating paths of fast waves in cancellous bone.

Longitudinal association between teen sexting and sexual behavior.

PubMed

Temple, Jeff R; Choi, HyeJeong

2014-11-01

This study examines the temporal sequencing of sexting and sexual intercourse and the role of active sexting (sending a nude picture) in mediating the relationship between passive sexting (asking or being asked for a nude picture) and sexual behaviors. Data are from Wave 2 (spring 2011) and Wave 3 (spring 2012) of an ongoing 6-year longitudinal study of high school students in southeast Texas. Participants included 964 ethnically diverse adolescents with a mean age of 16.09 years (56% female; 31% African American, 29% Caucasian, 28% Hispanic, 12% other). Retention rate for 1-year follow-up was 93%. Participants self-reported history of sexual activity (intercourse, risky sex) and sexting (sent, asked, been asked). Using path analysis, we examined whether teen sexting at baseline predicted sexual behavior at 1-year follow-up and whether active sexting mediated the relationship between passive sexting and sexual behavior. The odds of being sexually active at Wave 3 were 1.32 times larger for youth who sent a sext at Wave 2, relative to counterparts. However, sexting was not temporally associated with risky sexual behaviors. Consistent with our hypothesis, active sexting at Wave 2 mediated the relationship between asking or being asked for a sext and having sex over the next year. This study extends cross-sectional literature and supports the notion that sexting fits within the context of adolescent sexual development and may be a viable indicator of adolescent sexual activity. Copyright © 2014 by the American Academy of Pediatrics.

WINDII airglow observations of wave superposition and the possible association with historical "bright nights"

NASA Astrophysics Data System (ADS)

Shepherd, G. G.; Cho, Y.-M.

2017-07-01

Longitudinal variations of airglow emission rate are prominent in all midlatitude nighttime O(1S) lower thermospheric data obtained with the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS). The pattern generally appears as a combination of zonal waves 1, 2, 3, and 4 whose phases propagate at different rates. Sudden localized enhancements of 2 to 4 days duration are sometimes evident, reaching vertically integrated emission rates of 400 R, a factor of 10 higher than minimum values for the same day. These are found to occur when the four wave components come into the same phase at one longitude. It is shown that these highly localized longitudinal maxima are consistent with the historical phenomena known as "bright nights" in which the surroundings of human dark night observers were seen to be illuminated by this enhanced airglow.