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Sample records for acoustoelastic lamb wave

  1. Investigating the thermally induced acoustoelastic effect in isotropic media with Lamb waves

    PubMed Central

    Dodson, Jacob C.; Inman, Daniel J.

    2014-01-01

    Elastic wave velocities in metallic structures are affected by variations in environmental conditions such as changing temperature. This paper extends the theory of acoustoelasticity by allowing thermally induced strains in unconstrained isotropic media, and it experimentally examines the velocity variation of Lamb waves in aluminum plates (AL-6061) due to isothermal temperature deviations. This paper presents both thermally induced acoustoelastic constants and thermally varying effective Young's modulus and Poisson's ratio which include the third order elastic material constants. The experimental thermal sensitivity of the phase velocity (∂vP/∂θ) for both the symmetric and antisymmetric modes are bounded by two theories, the acoustoelastic Lamb wave theory with thermo-acoustoelastic tensors and the thermoelastic Lamb wave theory using an effective thermo-acoustoelastic moduli. This paper shows the theoretical thermally induced acoustoelastic Lamb wave thermal sensitivity (∂vP/∂θ) is an upper bound approximation of the experimental thermal changes, but the acoustoelastic Lamb wave theory is not valid for predicting the antisymmetric (A0) phase velocity at low frequency-thickness values, <1.55 MHz mm for various temperatures. PMID:25373955

  2. Investigating the thermally induced acoustoelastic effect in isotropic media with Lamb waves.

    PubMed

    Dodson, Jacob C; Inman, Daniel J

    2014-11-01

    Elastic wave velocities in metallic structures are affected by variations in environmental conditions such as changing temperature. This paper extends the theory of acoustoelasticity by allowing thermally induced strains in unconstrained isotropic media, and it experimentally examines the velocity variation of Lamb waves in aluminum plates (AL-6061) due to isothermal temperature deviations. This paper presents both thermally induced acoustoelastic constants and thermally varying effective Young's modulus and Poisson's ratio which include the third order elastic material constants. The experimental thermal sensitivity of the phase velocity (∂v(P)/∂θ) for both the symmetric and antisymmetric modes are bounded by two theories, the acoustoelastic Lamb wave theory with thermo-acoustoelastic tensors and the thermoelastic Lamb wave theory using an effective thermo-acoustoelastic moduli. This paper shows the theoretical thermally induced acoustoelastic Lamb wave thermal sensitivity (∂v(P)/∂θ) is an upper bound approximation of the experimental thermal changes, but the acoustoelastic Lamb wave theory is not valid for predicting the antisymmetric (A0) phase velocity at low frequency-thickness values, <1.55 MHz mm for various temperatures. PMID:25373955

  3. Experimental study of the acoustoelastic Lamb wave in thin plates

    NASA Astrophysics Data System (ADS)

    Pei, Ning; Bond, Leonard J.

    2016-02-01

    Many factors can cause residual stresses in industry, like rolling, welding and coating. Residual stresses can have both benefits and shortcomings on components, so it is important to find the residual stresses out and enhance its benefits part and get rid of its harmful part. There are many methods for residual stresses detection and ultrasonic method turns out to be a good one for it is nondestructive, relative cheap and portable. The critically refracted longitudinal (LCR) wave is widely used for it is regarded most sensitive to stress and less sensitive to texture which can influence detection results. Ultrasonic methods for residual stresses detection are based on time of flight (TOF) measurement, but because the measurement should reach nanosecond to show stress change, there are many other factors that can influence TOF, like temperature, texture of the components and even the thickness of the couplant. So increasing the TOF's sensitivity to stress is very important. In this paper the relationships between velocity and frequency are studied experimentally[6] for different Lamb modes, under various stress loadings. The result shows that the sensitivity of different modes various a lot, the A1 mode is the most sensitivity, compared to S0, S1 and A0 modes; if the force is added to 100 MPa, the change stress of A1 mode can be as large to 80 m/s, which is about 10 times more sensitive than the traditional bulk wave. This makes it as a good choice for residual stress detection.

  4. Continuous waves probing in dynamic acoustoelastic testing

    NASA Astrophysics Data System (ADS)

    Scalerandi, M.; Gliozzi, A. S.; Ait Ouarabi, M.; Boubenider, F.

    2016-05-01

    Consolidated granular media display a peculiar nonlinear elastic behavior, which is normally analysed with dynamic ultrasonic testing exploiting the dependence on amplitude of different measurable quantities, such as the resonance frequency shift, the amount of harmonics generation, or the break of the superposition principle. However, dynamic testing allows measuring effects which are averaged over one (or more) cycles of the exciting perturbation. Dynamic acoustoelastic testing has been proposed to overcome this limitation and allow the determination of the real amplitude dependence of the modulus of the material. Here, we propose an implementation of the approach, in which the pulse probing waves are substituted by continuous waves. As a result, instead of measuring a time-of-flight as a function of the pump strain, we study the dependence of the resonance frequency on the strain amplitude, allowing to derive the same conclusions but with an easier to implement procedure.

  5. Ultrasonic Lamb wave tomography

    NASA Astrophysics Data System (ADS)

    Leonard, Kevin R.; Malyarenko, Eugene V.; Hinders, Mark K.

    2002-12-01

    Nondestructive evaluation (NDE) of aerospace structures using traditional methods is a complex, time-consuming process critical to maintaining mission readiness and flight safety. Limited access to corrosion-prone structure and the restricted applicability of available NDE techniques for the detection of hidden corrosion or other damage often compound the challenge. In this paper we discuss our recent work using ultrasonic Lamb wave tomography to address this pressing NDE technology need. Lamb waves are ultrasonic guided waves, which allow large sections of aircraft structures to be rapidly inspected for structural flaws such as disbonds, corrosion and delaminations. Because the velocity of Lamb waves depends on thickness, for example, the travel times of the fundamental Lamb modes can be converted into a thickness map of the inspection region. However, extracting quantitative information from Lamb wave data has always involved highly trained personnel with a detailed knowledge of mechanical waveguide physics. Our work focuses on tomographic reconstruction to produce quantitative maps that can be easily interpreted by technicians or fed directly into structural integrity and lifetime prediction codes. Laboratory measurements discussed here demonstrate that Lamb wave tomography using a square perimeter array of transducers with algebraic reconstruction tomography is appropriate for detecting flaws in aircraft materials. The speed and fidelity of the reconstruction algorithms as well as practical considerations for person-portable array-based systems are discussed in this paper.

  6. Measurement of acoustoelastic effect of Rayleigh surface waves using laser ultrasonics

    SciTech Connect

    Lu, W.Y.; Peng, L.W.; Holland, S.

    1997-11-01

    The acoustoelastic effect refers to the fact that elastic wave velocities vary with stress. Measurements of the change in stress induced velocity yield information which leads to the determination of stresses. Some work has been done to explore the possibility of using ultrasonic waves, including bulk longitudinal and shear waves as well as surface waves, for the nondestructive evaluation of stresses. This paper focuses on Rayleigh surface waves, which have the advantage of detecting both surface stresses and stress gradients. Piezoelectric or electromagnetic acoustic transducers have been used for the application of Rayleigh waves in the acoustoelastic measurement of stress. The size of these transducers and their fixtures limit the distance between transducers. Sharp edge wedges are usually bound to the pick-up piezoelectric transducers, known as the Rayleigh or surface wave device (SWD), to provide a better spatial resolution when the stress field is not uniform. The smallest distance reported is 11 mm. On the other hand, acoustic microscopes (AM) can measure localized stress for a very small area, from 30 {micro}m to 2 mm. Both SWD and AM method may lack the agility required for general applications. Laser ultrasonics (LU) is a method for optical generation and detection of ultrasound. The generation and detection areas can be focused to very small spot sizes, less than 1 mm, which allow velocity measurements to be made over a path length of a few millimeters. The LU technique is non-contact and can be applied remotely; it has many potential applications. The authors used the LU technique to measure the acoustoelastic behavior of an aluminum alloy, A16061-T6.

  7. Lamb Wave Helical Ultrasonic Tomography

    NASA Astrophysics Data System (ADS)

    Leonard, K. R.; Hinders, M. K.

    2004-02-01

    Ultrasonic guided waves have been used for a wide variety of ultrasonic inspection techniques. We describe here a new variation called helical ultrasound tomography (HUT). This new technique, among other things, has direct application to advanced pipe inspection. HUT uses guided ultrasonic waves along with an adaptation of the tomographic reconstruction algorithms developed by seismologists for what they call "cross borehole" tomography. In HUT, the Lamb-like guided waves travel in various helical crisscross paths between two parallel circumferential transducer arrays instead of the planar crisscross seismic paths between two boreholes. Although the measurement itself is fairly complicated, the output of the tomographic reconstruction is a readily interpretable map of a quantity of interest such as pipe wall thickness. We demonstrate the feasibility of the HUT technique via laboratory scans on steel pipe segments into which controlled thinnings have been introduced.

  8. Lamb Wave Tomography for Corrosion Mapping

    NASA Technical Reports Server (NTRS)

    Hinders, Mark K.; McKeon, James C. P.

    1999-01-01

    As the world-wide civil aviation fleet continues to age, methods for accurately predicting the presence of structural flaws-such as hidden corrosion-that compromise airworthiness become increasingly necessary. Ultrasonic guided waves, Lamb waves, allow large sections of aircraft structures to be rapidly inspected. However, extracting quantitative information from Lamb wave data has always involved highly trained personnel with a detailed knowledge of mechanical-waveguide physics. Our work focuses on using a variety of different tomographic reconstruction techniques to graphically represent the Lamb wave data in images that can be easily interpreted by technicians. Because the velocity of Lamb waves depends on thickness, we can convert the travel times of the fundamental Lamb modes into a thickness map of the inspection region. In this paper we show results for the identification of single or multiple back-surface corrosion areas in typical aluminum aircraft skin structures.

  9. Efficient laser generation of Lamb waves.

    PubMed

    Huke, Philipp; Schröder, Martin; Hellmers, Sandra; Kalms, Michael; Bergmann, Ralf B

    2014-10-15

    We report about the efficient generation of Lamb waves for nondestructive testing (NDT) of carbon fiber reinforced plastics (CFRP) with spatially formed laser beams. Therefore we describe the successful introduction of a liquid crystal on silicon (LCoS)-based spatial light modulator (SLM) to create predetermined spatial laser light distributions for a flexible Lamb wave excitation. We investigate the influence of the formed beam profiles of the generation laser to the resulting Lamb wave. The further objective of the study is the close adaptation of the laser-generated guided waves to a specific testing situation and an optimized defect evaluation. PMID:25361087

  10. Dynamic acousto-elastic test using continuous probe wave and transient vibration to investigate material nonlinearity.

    PubMed

    Eiras, J N; Vu, Q A; Lott, M; Payá, J; Garnier, V; Payan, C

    2016-07-01

    This study demonstrates the feasibility of the dynamic acousto-elastic effect of a continuous high frequency wave for investigating the material nonlinearity upon transient vibration. The approach is demonstrated on a concrete sample measuring 15×15×60cm(3). Two ultrasonic transducers (emitter and receiver) are placed at its middle span. A continuous high frequency wave of 500kHz propagates through the material and is modulated with a hammer blow. The position of the hammer blow on the sample is configured to promote the first bending mode of vibration. The use of a continuous wave allows discrete time extraction of the nonlinear behavior by a short-time Fourier transform approach, through the simultaneous comparison of a reference non-modulated signal and an impact-modulated signal. The hammer blow results in phase shifts and variations of signal amplitude between reference and perturbed signals, which are driven by the resonant frequency of the sample. Finally, a comprehensive analysis of the relaxation mechanisms (modulus and attenuation recovery) is conducted to untangle the coupled fast and slow hysteretic effects. PMID:27018754

  11. Low frequency energy scavenging using sub-wave length scale acousto-elastic metamaterial

    NASA Astrophysics Data System (ADS)

    Ahmed, Riaz U.; Banerjee, Sourav

    2014-11-01

    This letter presents the possibility of energy scavenging (ES) utilizing the physics of acousto-elastic metamaterial (AEMM) at low frequencies (<˜3KHz). It is proposed to use the AEMM in a dual mode (Acoustic Filter and Energy Harvester), simultaneously. AEMM's are typically reported for filtering acoustic waves by trapping or guiding the acoustic energy, whereas this letter shows that the dynamic energy trapped inside the soft constituent (matrix) of metamaterials can be significantly harvested by strategically embedding piezoelectric wafers in the matrix. With unit cell AEMM model, we experimentally asserted that at lower acoustic frequencies (< ˜3 KHz), maximum power in the micro Watts (˜35µW) range can be generated, whereas, recently reported phononic crystal based metamaterials harvested only nano Watt (˜30nW) power against 10KΩ resistive load. Efficient energy scavengers at low acoustic frequencies are almost absent due to large required size relevant to the acoustic wavelength. Here we report sub wave length scale energy scavengers utilizing the coupled physics of local, structural and matrix resonances. Upon validation of the argument through analytical, numerical and experimental studies, a multi-frequency energy scavenger (ES) with multi-cell model is designed with varying geometrical properties capable of scavenging energy (power output from ˜10µW - ˜90µW) between 0.2 KHz and 1.5 KHz acoustic frequencies.

  12. Damage detection in concrete using Lamb waves

    NASA Astrophysics Data System (ADS)

    Jung, Young-Chul; Na, Won-Bae; Kundu, Tribikram; Ehsani, Mohammad R.

    2000-06-01

    The feasibility of detecting defects in concrete beams using Lamb waves is investigated in this paper. The Lamb wave can propagate a long distance along the specimen as the guided wave and is sensitive to defects that are smaller than its wavelength. The traditional ultrasonic methods for inspecting defects in concrete use reflection, transmission and scattering of longitudinal waves by internal defects. In traditional techniques signal amplitude and time of flight measurements provide information about the internal defects in concrete. These methods are time consuming and often fail to detect a variety of defects, such as internal corrosion, honeycombs, closed cracks and small inclusions. In this paper Lamb waves are used to detect those defects in concrete beams with and without reinforcement. The Lamb wave technique is found to be reliable for detecting such defects. The effect of separation or delamination between concrete and reinforcing steel bars on the Lamb wave propagation characteristics is also investigated. Corrosion of rebars can cause this delamination. It is found that the cylindrical guided waves propagating along the steel rebars are very sensitive to the degree of delamination between the concrete and the rebars. This investigation shows that the Lamb wave inspection technique is an efficient and effective tool for health monitoring of concrete structures.

  13. A Discontinuous Galerkin method with a modified penalty flux for the propagation and scattering of acousto-elastic waves

    NASA Astrophysics Data System (ADS)

    Ye, Ruichao; de Hoop, Maarten V.; Petrovitch, Christopher L.; Pyrak-Nolte, Laura J.; Wilcox, Lucas C.

    2016-02-01

    We develop an approach for simulating acousto-elastic wave phenomena, including scattering from fluid-solid boundaries, where the solid is allowed to be anisotropic, with the Discontinuous Galerkin method. We use a coupled first-order elastic strain-velocity, acoustic velocity-pressure formulation, and append penalty terms based on interior boundary continuity conditions to the numerical (central) flux so that the consistency condition holds for the discretized Discontinuous Galerkin weak formulation. We incorporate the fluid-solid boundaries through these penalty terms and obtain a stable algorithm. Our approach avoids the diagonalization into polarized wave constituents such as in the approach based on solving elementwise Riemann problems.

  14. A discontinuous Galerkin method with a modified penalty flux for the propagation and scattering of acousto-elastic waves

    NASA Astrophysics Data System (ADS)

    Ye, Ruichao; de Hoop, Maarten V.; Petrovitch, Christopher L.; Pyrak-Nolte, Laura J.; Wilcox, Lucas C.

    2016-05-01

    We develop an approach for simulating acousto-elastic wave phenomena, including scattering from fluid-solid boundaries, where the solid is allowed to be anisotropic, with the discontinuous Galerkin method. We use a coupled first-order elastic strain-velocity, acoustic velocity-pressure formulation, and append penalty terms based on interior boundary continuity conditions to the numerical (central) flux so that the consistency condition holds for the discretized discontinuous Galerkin weak formulation. We incorporate the fluid-solid boundaries through these penalty terms and obtain a stable algorithm. Our approach avoids the diagonalization into polarized wave constituents such as in the approach based on solving elementwise Riemann problems.

  15. Optimization of Lamb wave inspection techniques

    NASA Astrophysics Data System (ADS)

    Alleyne, David N.; Cawley, Peter

    Some problems associated with Lamb wave inspection techniques are briefly reviewed, and factors to be considered when selecting a practical Lamb wave inspection regime and ways to minimize possible problems are discussed. Tests on a butt-welded steel plate with simulated weld defects of different depths demonstrate that, operating below the a1 cut-off frequency with judicious selection of the testing technique, the presence of defects with depths around 30 percent of the plate thickness can be detected reliably from changes in the shape of the received waveform, The 2D Fourier transform method makes it possible to determine the amplitudes of the different propagating Lamb modes over the full frequency range of the input, yielding information which can be used for defect sizing.

  16. Lamb wave behavior in bridge girder geometries

    NASA Astrophysics Data System (ADS)

    Oppenheim, I. J.; Greve, D. W.; Tyson, N. L.

    2006-03-01

    Lamb waves in plates and in cylindrical pipes have been the subject of extensive study, largely because they propagate great distances with little attenuation, and can therefore be used to detect flaws. In this paper we report finite element simulations and experimental studies of Lamb waves in steel bridge girder geometries. In our studies the Lamb waves are generated by PZT wafer-type transducers mounted on the girder web, driven by a windowed sinusoidal pulse; the pulse center frequency is chosen to yield a frequency-thickness product of roughly 1 MHz-mm, at which the group velocities of the S0 and A0 waves are well separated, and at which waves in higher modes are theoretically absent. Transient dynamic finite element simulations, both in 2D and in 3D, were performed using FEMLAB and ABAQUS. The simulations show that transmission at the web-flange joint creates guided waves in the flanges that travel at different velocities from the Lamb waves in the web, and that reflection at the web-flange joint creates a largely straight-crested wavefront for the Lamb waves in the web remote from the source. Simulation studies also illustrate the acoustic influence of plate girder transverse stiffeners, which is observed to be relatively small. A welded steel plate girder laboratory specimen was fabricated with proportions typical of highway bridge members, at approximately half-scale. The web height is 920 mm and thickness is 3.2 mm, for a representative height-thickness ratio of 288; the flange width is 100 mm and thickness is 6.4 mm, for a representative width-thickness ratio of 16. Small PZT transducers, roughly 6.4 x 6.4 x 0.6 mm, excited at less than 10 V, produce ample signals. We compare simulation results and experimental measurements for Lamb wave illumination of the plate girder segment. We also discuss the detection of cracks, simulated experimentally by saw cuts of varying dimensions in the laboratory girder specimen.

  17. Lamb Wave Response of Fatigued Composite Samples

    NASA Technical Reports Server (NTRS)

    Seale, Michael; Smith, Barry T.; Prosser, William H.; Masters, John E.

    1994-01-01

    Composite materials are being more widely used today by aerospace, automotive, sports equipment, and a number of other commercial industries because of their advantages over conventional metals. Composites have a high strength-to-weight ratio and can be constructed to meet specific design needs. Composite structures are already in use in secondary parts of the Douglas MD-11 and are planned to be used in the new MD-12X. Plans also exist for their use in primary and secondary structures on the Boeing 777. Douglas proposed MD-XX may also incorporate composite materials into primary structures such as the wings and tail. Use of composites in these structures offers weight savings, corrosion resistance, and improved aerodynamics. Additionally, composites have been used to repair cracks in many B-1Bs where traditional repair techniques were not very effective. Plans have also been made to reinforce all of the remaining B-1s with composite materials. Verification of the structural integrity of composite components is needed to insure safe operation of these aerospace vehicles. One aspect of the use of these composites is their response to fatigue. To track this progression of fatigue in aerospace structures, a convenient method to nondestructively monitor this damage needs to be developed. Traditional NDE techniques used on metals are not easily adaptable to composites due to the inhomogeneous and anisotropic nature of these materials. Finding an effective means of nondestructively monitoring fatigue damage is extremely important to the safety and reliability of such structures. Lamb waves offer one method of evaluating these composite materials. As a material is fatigued, the modulus degrades. Since the Lamb wave velocity can be related to the modulus of the material, an effective tool can be developed to monitor fatigue damage in composites by measuring the velocity of these waves. In this work, preliminary studies have been conducted which monitor fatigue damage in

  18. Lamb wave dispersion under finite plastic deformation

    NASA Astrophysics Data System (ADS)

    Liu, Kuang C.; Ghoshal, Anindya

    2013-04-01

    This paper presents a preliminary study of the effects residual plastic strains have on Lamb wave velocities and time of flight measurements. The potential application of this research is non-destructive evaluation and structural health monitoring, particularly reconstructing plastic strain fields. The finite deformation of a semi-infinite plate due to residual plastic strain is used to accommodate the changes in plate thickness and elongation. The results show that the S0 mode exhibits significant variations in group velocity in the highly dispersive regions, as much as a 2% increase in velocity with a 1% plastic strain. However, for time of flight measurements, the plate elongation had an order of magnitude effect rather than showing velocity changes. By exploiting time delay measurements, it may be possible to use wave speed measurements to determine plastic zones through Lamb-like waves.

  19. Liquid level sensor using ultrasonic Lamb waves.

    PubMed

    Sakharov, V E; Kuznetsov, S A; Zaitsev, B D; Kuznetsova, I E; Joshi, S G

    2003-06-01

    This paper describes a novel, noninvasive method for measurement of liquid level in closed metal tanks that are under high pressure. It is based on the use of ultrasonic Lamb waves propagating along the tank wall. Contact with liquid substantially changes the characteristics of these waves and this can be used as an indicator of liquid presence. Theoretical analysis shows that the symmetric and antisymmetric Lamb wave modes, both fundamental and higher order, are sensitive to presence of the liquid. The optimal wave frequency depends on the thickness of the tank wall and wall material. A prototype level sensor based on this principle has been developed. It uses two pairs of wedge transducers to generate and detect Lamb waves propagating along the circumference of the gas tank. An operating frequency of 100 kHz is found to be optimal for use with tanks having a wall thickness of 30-50 mm. Prototype sensors developed under this program have been used successfully in oil fields in the far northern region of Russia. PMID:12782266

  20. Crack Detection with Lamb Wave Wavenumber Analysis

    NASA Technical Reports Server (NTRS)

    Tian, Zhenhua; Leckey, Cara; Rogge, Matt; Yu, Lingyu

    2013-01-01

    In this work, we present our study of Lamb wave crack detection using wavenumber analysis. The aim is to demonstrate the application of wavenumber analysis to 3D Lamb wave data to enable damage detection. The 3D wavefields (including vx, vy and vz components) in time-space domain contain a wealth of information regarding the propagating waves in a damaged plate. For crack detection, three wavenumber analysis techniques are used: (i) two dimensional Fourier transform (2D-FT) which can transform the time-space wavefield into frequency-wavenumber representation while losing the spatial information; (ii) short space 2D-FT which can obtain the frequency-wavenumber spectra at various spatial locations, resulting in a space-frequency-wavenumber representation; (iii) local wavenumber analysis which can provide the distribution of the effective wavenumbers at different locations. All of these concepts are demonstrated through a numerical simulation example of an aluminum plate with a crack. The 3D elastodynamic finite integration technique (EFIT) was used to obtain the 3D wavefields, of which the vz (out-of-plane) wave component is compared with the experimental measurement obtained from a scanning laser Doppler vibrometer (SLDV) for verification purposes. The experimental and simulated results are found to be in close agreement. The application of wavenumber analysis on 3D EFIT simulation data shows the effectiveness of the analysis for crack detection. Keywords: : Lamb wave, crack detection, wavenumber analysis, EFIT modeling

  1. Lamb Wave Assessment of Fiber Volume Fraction in Composites

    NASA Technical Reports Server (NTRS)

    Seale, Michael D.; Smith, Barry T.; Prosser, W. H.; Zalameda, Joseph N.

    1998-01-01

    Among the various techniques available, ultrasonic Lamb waves offer a convenient method of examining composite materials. Since the Lamb wave velocity depends on the elastic properties of a material, an effective tool exists to evaluate composites by measuring the velocity of these waves. Lamb waves can propagate over long distances and are sensitive to the desired in-plane elastic properties of the material. This paper discusses a study in which Lamb waves were used to examine fiber volume fraction variations of approximately 0.40-0.70 in composites. The Lamb wave measurements were compared to fiber volume fractions obtained from acid digestion tests. Additionally, a model to predict the fiber volume fraction from Lamb wave velocity values was evaluated.

  2. Background Lamb waves in the Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Nishida, K.; Kobayashi, N.; Fukao, Y.

    2013-12-01

    Lamb waves of the Earth's atmosphere in the millihertz band have been considered as transient phenomena excited only by large events [e.g. the major volcanic eruption of Krakatoa in 1833, the impact of Siberian meteorite in 1908, the testing of large nuclear tests and the huge earthquakes, Garrett1969]. In a case of the solid Earth, observation of background free oscillations in the millihertz band-now known as Earth's background free oscillations or seismic hum, has been firmly established. Above 5 mHz, their dominant excitation sources are oceanic infragravity waves. At 3.7 and 4.4 mHz an elasto-acoustic resonance between the solid Earth and the atmosphere was observed [Nishida et al., 2000]. These seismic observations show that the contribution of atmospheric disturbances to the seismic hum is dominant below 5 mHz. Such contribution implies background excitations of acoustic-gravity waves in this frequency range. For direct detection of the background acoustic-gravity waves, our group conducted observations using an array of barometers [Nishida et al. 2005]. However, the spatial scale of the array of about 10 km was too small to detect acoustic modes below 10 mHz. Since then, no direct observations of these waves have been reported. In 2011, 337 high-resolution microbarometers were installed on a continental scale at USArray Transportable Array. The large and dense array enables us to detect the background atmospheric waves. Here, we show the first evidence of background Lamb waves in the Earth's atmosphere from 0.2 to 10 mHz, based on the array analysis of microbarometer data from the USArray in 2012. The observations suggest that the excitation sources are atmospheric disturbances in the troposphere. Theoretically, their energy in the troposphere tunnels into the thermosphere at a resonant frequency via thermospheric gravity wave, where the observed amplitudes indeed take a local minimum. The energy leak through the frequency window could partly contribute to

  3. Hidden Corrosion Detection in Aircraft Metallic Structures Using Lamb Waves

    SciTech Connect

    Titry, C.; Lepoutre, F.

    2005-04-09

    The corrosion of aeronautics structures in aluminum is difficult to detect at an early stage. Lamb waves are sometimes very sensitive to this damage and can be considered as good candidates for its detection. Unfortunately, the complex time evolution of Lamb wave signals makes difficult both utilization and interpretation of their interaction with defects. This paper demonstrates that, for many reasons, the analysis based on wavelets transform is of great help for recognition of Lamb modes and allows the cartography of corroded areas.

  4. Lamb wave detection with a fiber optic angular displacement sensor

    NASA Astrophysics Data System (ADS)

    Garcia, Marlon R.; Sakamoto, João. M. S.; Higuti, Ricardo T.; Kitano, Cláudio

    2015-09-01

    In this work we show that the fiber optic angular displacement sensor is capable of Lamb wave detection, with results comparable to a piezoelectric transducer. Therefore, the fiber optic sensor has a great potential to be used as the Lamb wave ultrasonic receiver and to perform non-destructive and non-contact testing.

  5. Comparison of double crosshole and fanbeam Lamb wave ultrasonic tomography

    NASA Astrophysics Data System (ADS)

    Hinders, Mark K.; Malyarenko, Eugene V.

    2001-04-01

    Ultrasonic guided waves, Lamb waves, allow large sections of aircraft structures to be rapidly inspected. However, extracting quantitative information from Lamb wave data has always involved highly trained personnel with a detailed knowledge of mechanical waveguide physics. The work discussed here focuses on a variety of different tomographic reconstruction techniques to graphically represent the Lamb wave data in quantitative maps that can be easily interpreted by technicians. Because the velocity of Lamb waves depends on thickness, for example, the traveltimes of the fundamental Lamb modes can be converted into a thickness map of the inspection region. This paper describes two potentially practical implementations of Lamb wave tomographic imaging techniques that can be optimized for in-the-field testing of large-area aircraft structures. Laboratory measurements discussed here demonstrate that Lamb wave tomography using either a ring of transducers with fan beam reconstructions, or a square array of transducers with algebraic reconstruction tomography, is appropriate for detecting flaws in multilayer aircraft materials. The speed and fidelity of the reconstruction algorithms as well as practical considerations for person-portable array-based systems are discussed in this presentation.

  6. Anomalous and negative reflection of Lamb waves in mode conversion

    NASA Astrophysics Data System (ADS)

    Germano, M.; Alippi, A.; Bettucci, A.; Mancuso, G.

    2012-01-01

    Mode conversion is an important feature of wave propagation used in ultrasonic nondestructive testing with Lamb waves. When a wave packet with a given central frequency, and a correspondent central wavenumber, impinges on the free edge of a plate, the reflected wave generally is a weighed combination of all the possible modes compatible with the given frequency. Under particular conditions, only one wave packet is reflected with a distinct central wavenumber compared to the incident one. In such a case, according to Snell's law, the reflection angle is different from the incident one (anomalous reflection). In this article, experimental results are presented on anomalous reflection on a free edge of a thin plate of a Lamb wave packet; moreover, experimental results are reported on a Lamb wave packet that is reflected at an angle lying on the same side, with respect to the normal direction, of the impinging wave (negative reflection). Negative reflection of Lamb waves has been obtained through mode conversion taking place at the free edge of a thin plate of constant thickness: More precisely, a symmetric S1 Lamb mode has been converted into the same mode but with phase velocity antiparallel to group velocity, so obtaining the so-called backward-propagating Lamb wave packet.

  7. DETECTION OF DISBONDING IN GLARE COMPOSITES USING LAMB WAVE APPROACH

    SciTech Connect

    Huang Qiaojian; Balogun, Oluwaseyi; Yang Ningli; Regez, Brad; Krishnaswamy, Sridhar

    2010-02-22

    Lamb-waves can be used to detect disbonds in composite plates. In this work, a photoacoustic technique was first applied to measure the dispersive property of a GLAss-REinforced (GLARE) composite panel. The measured phase velocity dispersion curves are consistent with the theoretical calculation using the classical transfer matrix method for layered media. Based on the obtained properties, a finite element method (FEM) model was constructed to study the influence of a disbond void on the Lamb wave propagation in the GLARE plate. It is found that the displacement amplitudes of the A{sub o} mode Lamb wave decrease while its travel time increases as the disbond size increases.

  8. Pump and probe waves in dynamic acousto-elasticity: Comprehensive description and comparison with nonlinear elastic theories

    NASA Astrophysics Data System (ADS)

    Rivière, J.; Renaud, G.; Guyer, R. A.; Johnson, P. A.

    2013-08-01

    Standard nonlinear ultrasonic methods such as wave frequency mixing or resonance based measurements allow one to extract average, bulk variations of modulus and attenuation versus strain level. In contrast, dynamic acousto-elasticity (DAE) provides the elastic behavior over the entire dynamic cycle including hysteresis and memory effects, detailing the full nonlinear behavior under tension and compression. In this work, we address experimental difficulties and apply new processing methods, illustrating them with a Berea sandstone sample. A projection procedure is used to analyze the complex nonlinear signatures and extract the harmonic content. Amplitude dependences of the harmonic content are compared with existing models. We show that a combination of classical and hysteretic nonlinear models capture most of the observed phenomena. Some differences between existing models and experimental data are highlighted, however. A progressive decrease of the power-law amplitude dependence is found for harmonics larger than the second and for strains larger than 10-6. This observation is related to the phenomenon of acoustic conditioning that brings the material to a metastable state for each new excitation amplitude. Analysis of the steady-state regime provides additional information regarding acoustic conditioning, i.e., a progressive decrease of the amplitude of odd harmonics during excitation time with a log(t)-dependence. This observation confirms that the harmonic content is affected by the conditioning. Experimental challenges addressed include the fact that the compressional mode used for DAE can be affected by bending/torsion modes: their influence is evaluated, and guidances are given to minimize effects.

  9. Lamb Wave Assessment of Fatigue and Thermal Damage in Composites

    NASA Technical Reports Server (NTRS)

    Seale, Michael D.; Smith, Barry T.; Prosser, W. H.

    2004-01-01

    Among the various techniques available, ultrasonic Lamb waves offer a convenient method of evaluating composite materials. Since the Lamb wave velocity depends on the elastic properties of a structure, an effective tool exists to monitor damage in composites by measuring the velocity of these waves. Lamb wave measurements can propagate over long distances and are sensitive to the desired in-plane elastic properties of the material. This paper describes two studies which monitor fatigue damage and two studies which monitor thermal damage in composites using Lamb waves. In the fatigue studies, the Lamb wave velocity is compared to modulus measurements obtained using strain gage measurements in the first experiment and the velocity is monitored along with the crack density in the second. In the thermal damage studies, one examines samples which were exposed to varying temperatures for a three minute duration and the second includes rapid thermal damage in composites by intense laser beams. In all studies, the Lamb wave velocity is demonstrated to be an excellent method to monitor damage in composites.

  10. Lamb wave propagation in negative Poisson's ratio composites

    NASA Astrophysics Data System (ADS)

    Remillat, Chrystel; Wilcox, Paul; Scarpa, Fabrizio

    2008-03-01

    Lamb wave propagation is evaluated for cross-ply laminate composites exhibiting through-the-thickness negative Poisson's ratio. The laminates are mechanically modeled using the Classical Laminate Theory, while the propagation of Lamb waves is investigated using a combination of semi analytical models and Finite Element time-stepping techniques. The auxetic laminates exhibit well spaced bending, shear and symmetric fundamental modes, while featuring normal stresses for A 0 mode 3 times lower than composite laminates with positive Poisson's ratio.

  11. Impact Localization Using Lamb Wave and Spiral FSAT

    NASA Astrophysics Data System (ADS)

    Rimal, Nischal

    Wear and tear exists in almost every physical infrastructure. Modern day science has something in its pocket to early detect such wear and tear known as Structural Health Monitoring (SHM). SHM features a key role in tracking a structural failure and could prevent loss of human lives and money. The size and prices of presently available defect detection devices make them not suitable for on-site SHM. The exploitation of directional transducers and Lamb wave propagation for SHM has been proposed. The basis of the project was to develop an accurate localization algorithm and implementation of Lamb waves to detect the crack present in the plate like structures. In regards, the use of Frequency Steerable Acoustic Transducer (FSAT) was studied. The theory governing the propagation of Lamb wave was reviewed. The derivation of the equations and dispersion curve of Lamb waves are included. FSAT was studied from both theoretical and application view of point. The experiments carried out give us better understanding of the FSAT excitation and Lamb wave generation and detection. The Lamb wave generation and crack localization algorithm was constructed and with the proposed algorithm, simulated impacts are detected.

  12. Lamb wave propagation in vibrating structures for effective health monitoring

    NASA Astrophysics Data System (ADS)

    Lu, Xubin; Soh, Chee Kiong; Avvari, Panduranga Vittal

    2015-03-01

    Lamb wave based Structural Health Monitoring (SHM) has received much attention during the past decades for its broad coverage and high sensitivity to damage. Lamb waves can be used to locate and quantify damage in static structures successfully. Nonetheless, structures are usually subjected to various external vibrations or oscillations. Not many studies are reported in the literature concerning the damage detecting ability of Lamb wave in oscillating structures which turns out to be a pivotal issue in the practical application of the SHM technique. For this reason in this study, the propagating capability of Lamb waves in a vibrating thin aluminum plate is examined experimentally. Two circular shaped piezoelectric wafer active transducers are surface-bonded on the aluminum plate where one acted as an actuator and another as a sensor. An arbitrary waveform generator is connected to the actuator for the generation of a windowed tone burst on the aluminum plate. An oscilloscope is connected to the sensor for receiving the traveled waves. An external shaker is used to generate out-of-plane external vibration on the plate structure. Time of flight (TOF) is a crucial parameter in most Lamb wave based SHM studies, which measures wave traveling time from the actuator to sensor. In the present study the influence of the external vibrations on the TOF is investigated. Experiments are performed under different boundary conditions of the plate, such as free-free and fixed by gluing. The effects of external vibrations in the frequency range between 10 Hz to 1000 Hz are analyzed. Comparisons are carried out between the resulting Lamb wave signals from the vibrating plate for different boundary conditions. Experimental results show that the external vibrations in relatively low frequency range do not change the TOF during the application of Lamb wave based SHM.

  13. Detection of internal defects in concrete panels by Lamb waves

    NASA Astrophysics Data System (ADS)

    Jung, Y. C.; Kundu, T.; Ehsani, M.

    2000-05-01

    It is investigated if internal defects in concrete beams can be detected by Lamb waves. To this aim, a number of concrete beams (8 in.×12 in.×40 in.) have been cast. Three types of defects—honeycomb, plexiglas inclusion and water-filled cracks—have been fabricated inside the beam during the casting process. Different Lamb modes have been generated in the beam by varying the signal frequency and transducer inclination angles. The Lamb waves propagate through the beam and then strike a receiving transducer. A function generator that sweeps the signal frequency continuously between 20 kHz to 160 kHz excites the transmitter. The received signal voltage (V) varies as a function of frequency (f). The V(f) curves are plotted over good and defective zones of the beam. These curves show good sensitivity of Lamb waves to defects. In other words, the shape and amplitude of the V(f) curve vary with the defect type. From this investigation it is concluded that different types of defects—honeycomb, inclusions and cracks—in concrete beams can be detected by the Lamb wave generated V(f) curves. It is also concluded that inclined transducers in a water pool give better results than the conventional direct contact type arrangement with Vaseline as the coupling gel.

  14. Adhesive joint evaluation by ultrasonic interface and lamb waves

    NASA Technical Reports Server (NTRS)

    Rokhlin, S. I.

    1986-01-01

    Some results on the application of interface and Lamb waves for the study of curing of thin adhesive layers were summarized. In the case of thick substrates (thickness much more than the wave length) the interface waves can be used. In this case the experimental data can be inverted and the shear modulus of the adhesive film may be explicitly found based on the measured interface wave velocity. It is shown that interface waves can be used for the study of curing of structural adhesives as a function of different temperatures and other experimental conditions. The kinetics of curing was studied. In the case of thin substrates the wave phenomena are much more complicated. It is shown that for successful measurements proper selection of experimental conditions is very important. This can be done based on theoretical estimations. For correctly selected experimental conditions the Lamb waves may be a sensitive probe of adhesive bond quality and may be used or cure monitoring.

  15. Orbital-type trapping of elastic Lamb waves.

    PubMed

    Lomonosov, Alexey M; Yan, Shi-Ling; Han, Bing; Zhang, Hong-Chao; Shen, Zhong-Hua

    2016-01-01

    The interaction of laser-generated Lamb waves propagating in a plate with a sharp-angle conical hole was studied experimentally and numerically. Part of the energy of the incident wave is trapped within the conic area in two ways: the antisymmetric Lamb wave orbiting the center of the hole and the wave localized at the acute edge. Parameters and conditions for optimal conversion of the incident wave into the trapped modes were studied in this work. Experiments were performed using the laser stroboscopic shearography technique, which delivers the time evolution of the acoustic field in the whole area of interest. The effect of trapping can be used for efficient damping, similar to the one-dimensional acoustical black hole effect. PMID:26298599

  16. Amplitude-dependent Lamb wave dispersion in nonlinear plates.

    PubMed

    Packo, Pawel; Uhl, Tadeusz; Staszewski, Wieslaw J; Leamy, Michael J

    2016-08-01

    The paper presents a perturbation approach for calculating amplitude-dependent Lamb wave dispersion in nonlinear plates. Nonlinear dispersion relationships are derived in closed form using a hyperelastic stress-strain constitutive relationship, the Green-Lagrange strain measure, and the partial wave technique integrated with a Lindstedt-Poincaré perturbation approach. Solvability conditions are derived using an operator formalism with inner product projections applied against solutions to the adjoint problem. When applied to the first- and second-order problems, these solvability conditions lead to amplitude-dependent, nonlinear dispersion corrections for frequency as a function of wavenumber. Numerical simulations verify the predicted dispersion shifts for an example nonlinear plate. The analysis and identification of amplitude-dependent, nonlinear Lamb wave dispersion complements recent research focusing on higher harmonic generation and internally resonant waves, which require precise dispersion relationships for frequency-wavenumber matching. PMID:27586758

  17. Amplitude-dependent contraction/elongation of nonlinear Lamb waves

    NASA Astrophysics Data System (ADS)

    Packo, Pawel; Staszewski, Wieslaw J.; Uhl, Tadeusz; Leamy, Michael J.

    2016-04-01

    Nonlinear elastic guided waves find application in various disciplines of science and engineering, such as non- destructive testing and structural health monitoring. Recent recognition and quantification of their amplitude- dependent changes in spectral properties has contributed to the development of new monitoring concepts for mechanical structures. The focus of this work is to investigate and predict amplitude-dependent shifts in Lamb wave dispersion curves. The theory for frequency/wavenumber shifts for plate waves, based on a Lindstedt-Poincaré perturbation approach, was presented by the authors in previous years. Equivalently, spectral properties changes can be seen as wavelength contraction/elongation. Within the proposed framework, the wavelength of a Lamb wave depends on several factors; e.g., wave amplitude and second-, third- and fourth-order elastic constants, and others. Various types of nonlinear effects are considered in presented studies. Sensitivity studies for model parameters, i.e. higher-order elastic constants, are performed to quantify their influence on Lamb wave frequency/wavenumber shifting, and to identify the key parameters governing wavelength tuning.

  18. On Lamb and Rayleigh wave convergence in viscoelastic tissues

    NASA Astrophysics Data System (ADS)

    Nenadic, Ivan Z.; Urban, Matthew W.; Aristizabal, Sara; Mitchell, Scott A.; Humphrey, Tye C.; Greenleaf, James F.

    2011-10-01

    Characterization of the viscoelastic material properties of soft tissue has become an important area of research over the last two decades. Our group has been investigating the feasibility of using a shear wave dispersion ultrasound vibrometry (SDUV) method to excite Lamb waves in organs with plate-like geometry to estimate the viscoelasticity of the medium of interest. The use of Lamb wave dispersion ultrasound vibrometry to quantify the mechanical properties of viscoelastic solids has previously been reported. Two organs, the heart wall and the spleen, can be readily modeled using plate-like geometries. The elasticity of these two organs is important because they change in pathological conditions. Diastolic dysfunction is the inability of the left ventricle (LV) of the heart to supply sufficient stroke volumes into the systemic circulation and is accompanied by the loss of compliance and stiffening of the LV myocardium. It has been shown that there is a correlation between high splenic stiffness in patients with chronic liver disease and strong correlation between spleen and liver stiffness. Here, we investigate the use of the SDUV method to quantify the viscoelasticity of the LV free-wall myocardium and spleen by exciting Rayleigh waves on the organ's surface and measuring the wave dispersion (change of wave velocity as a function of frequency) in the frequency range 40-500 Hz. An equation for Rayleigh wave dispersion due to cylindrical excitation was derived by modeling the excised myocardium and spleen with a homogenous Voigt material plate immersed in a nonviscous fluid. Boundary conditions and wave potential functions were solved for the surface wave velocity. Analytical and experimental convergence between the Lamb and Rayleigh waves is reported in a finite element model of a plate in a fluid of similar density, gelatin plate and excised porcine spleen and left-ventricular free-wall myocardium.

  19. Minimal model for spoof acoustoelastic surface states

    SciTech Connect

    Christensen, J. Willatzen, M.; Liang, Z.

    2014-12-15

    Similar to textured perfect electric conductors for electromagnetic waves sustaining artificial or spoof surface plasmons we present an equivalent phenomena for the case of sound. Aided by a minimal model that is able to capture the complex wave interaction of elastic cavity modes and airborne sound radiation in perfect rigid panels, we construct designer acoustoelastic surface waves that are entirely controlled by the geometrical environment. Comparisons to results obtained by full-wave simulations confirm the feasibility of the model and we demonstrate illustrative examples such as resonant transmissions and waveguiding to show a few examples of many where spoof elastic surface waves are useful.

  20. PVDF Multielement Lamb Wave Sensor for Structural Health Monitoring.

    PubMed

    Ren, Baiyang; Lissenden, Cliff J

    2016-01-01

    The characteristics of Lamb waves, which are multimodal and dispersive, provide both challenges and opportunities for structural health monitoring (SHM). Methods for nondestructive testing with Lamb waves are well established. For example, mode content can be determined by moving a sensor to different positions and then transforming the spatial-temporal data into the wavenumber-frequency domain. This mode content information is very useful because at every frequency each mode has a unique wavestructure, which is largely responsible for its sensitivity to material damage. Furthermore, mode conversion occurs when the waves interact with damage, making mode content an excellent damage detection feature. However, in SHM, the transducers are typically at fixed locations and are immovable. Here, an affixed polyvinylidene fluoride (PVDF) multielement sensor is shown to provide these same capabilities. The PVDF sensor is bonded directly to the waveguide surface, conforms to curved surfaces, has low mass, low profile, low cost, and minimal influence on passing Lamb waves. While the mode receivability is dictated by the sensor being located on the surface of the waveguide, both symmetric and antisymmetric modes can be detected and group velocities measured. PMID:26540682

  1. The propagation of coupled Lamb waves in multilayered arbitrary anisotropic composite laminates

    NASA Astrophysics Data System (ADS)

    Cunfu, He; Hongye, Liu; Zenghua, Liu; Bin, Wu

    2013-12-01

    Based on linear three-dimensional elasticity theory, the wave equations of coupled Lamb waves in multilayered arbitrary anisotropic composite laminates are derived using a Legendre orthogonal polynomial approach. The elastodynamic solution for the propagation of coupled Lamb waves in composite plates is also presented to determine the characteristics of coupled Lamb waves. To verify the applicability and validity of the method, two cases of bi-layered plates formed with isotropic components and anisotropic components, respectively, are primarily manipulated for comparison with earlier known results. Next, the dispersion curves, displacements and stress distributions of Lamb waves in multilayered anisotropic laminates are calculated. The effects of coupling and fiber orientation on the characteristics of the Lamb waves are illustrated. The potential usefulness of the fundamental modes of the coupled Lamb waves is discussed in detail.

  2. Low-cost ultrasonic lamb-wave transducer

    NASA Technical Reports Server (NTRS)

    Kammerer, C. C.

    1978-01-01

    Transducer propagates Lamb wave through thin aluminum sheet material. Model includes two elements that measure effects of damping and loading which, in turn, are indirectly equated to bond integrity. Transducer has been used to evaluate bond integrity of aluminum facing adhesively bonded to aluminum facing. Because of versatility, it is now possible to inspect many objects of different configurations that could not be reached with earlier transducers.

  3. Experimental and theoretical study of Rayleigh-Lamb wave propagation

    NASA Technical Reports Server (NTRS)

    Rogers, Wayne P.; Datta, Subhendu K.; Ju, T. H.

    1990-01-01

    Many space structures, such as the Space Station Freedom, contain critical thin-walled components. The structural integrity of thin-walled plates and shells can be monitored effectively using acoustic emission and ultrasonic testing in the Rayleigh-Lamb wave frequency range. A new PVDF piezoelectric sensor has been developed that is well suited to remote, inservice nondestructive evaluation of space structures. In the present study the new sensor was used to investigate Rayleigh-Lamb wave propagation in a plate. The experimental apparatus consisted of a glass plate (2.3 m x 25.4 mm x 5.6 mm) with PVDF sensor (3 mm diam.) mounted at various positions along its length. A steel ball impact served as a simulated acoustic emission source, producing surface waves, shear waves and longitudinal waves with dominant frequencies between 1 kHz and 200 kHz. The experimental time domain wave-forms were compared with theoretical predictions of the wave propagation in the plate. The model uses an analytical solution for the Green's function and the measured response at a single position to predict response at any other position in the plate. Close agreement was found between the experimental and theoretical results.

  4. Perturbation approach to dispersion curves calculation for nonlinear Lamb waves

    NASA Astrophysics Data System (ADS)

    Packo, Pawel; Staszewski, Wieslaw J.; Uhl, Tadeusz; Leamy, Michael J.

    2015-05-01

    Analysis of elastic wave propagation in nonlinear media has gained recent research attention due to the recognition of their amplitude-dependent behavior. This creates opportunities for increased accuracy of damage detection and localization, development of new structural monitoring strategies, and design of new structures with desirable acoustic behavior (e.g., amplitude-dependent frequency bandgaps, wave beaming, and filtering). This differs from more traditional nonlinear analysis approaches which target the prediction of higher harmonic growth. Of particular interest in this work is the analysis of amplitude-dependent shifts in Lamb wave dispersion curves. Typically, dispersion curves are calculated for nominally linear material parameters and geometrical features of a waveguide, even when the constitutive law is nonlinear. Instead, this work employs a Lindstedt - Poincare perturbation approach to calculate amplitude-dependent dispersion curves, and shifts thereof, for nonlinearly-elastic plates. As a result, a set of first order corrections to frequency (or equivalently wavenumber) are calculated. These corrections yield significant amplitude dependence in the spectral characteristics of the calculated waves, especially for high frequency waves, which differs fundamentally from linear analyses. Numerical simulations confirm the analytical shifts predicted. Recognition of this amplitude-dependence in Lamb wave dispersion may suggest, among other things, that the analysis of guided wave propagation phenomena within a fully nonlinear framework needs to revisit mode-mode energy flux and higher harmonics generation conditions.

  5. Inclusions detection using Lamb waves in flexible printed circuits.

    PubMed

    Jenot, F; Ouaftouh, M; Xu, W-J; Duquennoy, M; Ourak, M

    2006-12-22

    The materials used for the manufacture of flexible printed circuits are selected according to various characteristics: thermal and electrical behavior, moisture absorption, flexibility... Those are determined by the basic materials of the three components of the circuit, which are the conducting layer, the adhesive layer and the dielectric film. Such circuits have a typical thickness of about 200 microm and are therefore an interesting solution for a great number of electronic applications. However, these circuits can present various defects like inclusions, delaminations, cracks... In this work, we are interested in the detection of inclusions using guided waves propagation in such structures. These waves also called Lamb waves have the advantage of propagating over long distances while informing us about the totality of the inspected volume. According to the range of frequencies considered and the method used for their generation, it is possible to make profitable use of different propagation modes. To serve this purpose, laser-induced thermoelastic excitation of the first antisymmetric Lamb waves mode is studied. The results obtained are analysed using signal processing methods and then compared in order to clearly highlight the potentialities of these guided waves for the detection of inclusions in such samples. PMID:16808943

  6. Detecting Lamb waves with broad-band acousto-ultrasonic signals in composite structures

    NASA Technical Reports Server (NTRS)

    Kautz, Harold E.

    1992-01-01

    Lamb waves can be produced and detected in ceramic matrix composites (CMC) and metal matrix composites (MMC) plates using the acousto-ultrasonic configuration employing broadband transducers. Experimental dispersion curves of lowest symmetric and antisymmetric modes behave in a manner analogous to the graphite/polymer theoretical curves. In this study a basis has been established for analyzing Lamb wave velocities for characterizing composite plates. Lamb wave dispersion curves and group velocities were correlated with variations in axial stiffness and shear stiffness in MMC and CMC. For CMC, interfacial shear strength was also correlated with the first antisymmetric Lamb mode.

  7. Temperature effects in ultrasonic Lamb wave structural health monitoring systems.

    PubMed

    Lanza di Scalea, Francesco; Salamone, Salvatore

    2008-07-01

    There is a need to better understand the effect of temperature changes on the response of ultrasonic guided-wave pitch-catch systems used for structural health monitoring. A model is proposed to account for all relevant temperature-dependent parameters of a pitch-catch system on an isotropic plate, including the actuator-plate and plate-sensor interactions through shear-lag behavior, the piezoelectric and dielectric permittivity properties of the transducers, and the Lamb wave dispersion properties of the substrate plate. The model is used to predict the S(0) and A(0) response spectra in aluminum plates for the temperature range of -40-+60 degrees C, which accounts for normal aircraft operations. The transducers examined are monolithic PZT-5A [PZT denotes Pb(Zr-Ti)O3] patches and flexible macrofiber composite type P1 patches. The study shows substantial changes in Lamb wave amplitude response caused solely by temperature excursions. It is also shown that, for the transducers considered, the response amplitude changes follow two opposite trends below and above ambient temperature (20 degrees C), respectively. These results can provide a basis for the compensation of temperature effects in guided-wave damage detection systems. PMID:18646963

  8. The Interaction of Lamb Waves with Solid-Solid Interfaces

    NASA Astrophysics Data System (ADS)

    Drinkwater, B. W.; Castaings, M.; Hosten, B.

    2003-03-01

    This paper deals with the topic of the interaction of Lamb waves, more specifically the A0 and S0 modes, with a solid-solid interface. This solid-solid interface is the contact between two dry, rough surfaces and could represent a kissing bond in an adhesive joint or the contacting surfaces of a bolted joint. In this paper, a very thick elastomer with high internal damping is loaded against one surface of a glass plate to create a solid-solid interface. The principal effect is shown to be increased attenuation of the guided waves propagating along the glass plate. This attenuation is caused by leakage of energy from the plate into the elastomer, where it is dissipated due to high viscoelastic damping. It is shown that the increase in attenuation is strongly dependent on the compressive load applied across the solid-solid interface. This interface is represented as a spring layer in a continuum model of the multi-layered system. Both normal and shear stiffnesses of the interface are quantified from the attenuation of A0 and S0 Lamb waves measured at each step of the compressive loading.

  9. Experimental study of A0 Lamb wave tomography

    NASA Astrophysics Data System (ADS)

    Seher, Matthias; Huthwaite, Peter; Lowe, Michael; Cawley, Peter

    2015-03-01

    Corrosion damage in inaccessible regions presents a significant challenge to the petrochemical industry, and determining the remaining wall thickness is important to establish the remaining service life. Guided wave tomography is one solution and involves transmitting Lamb waves through the area of interest and using the received signals to reconstruct the remaining wall thickness. This avoids the need to access all points on the surface, making the technique well suited to inspection beneath supports. For this purpose a tomography system for pipe inspections is developed using low frequency A0 Lamb waves that are excited and detected with two arrays of electromagnetic acoustic transducers (EMATs). Two different defect depths are considered with different contrasts relative to the nominal wall thickness and in a first step, the repeatability of the measurements is demonstrated. Due to the limited view array configuration, the maximum depth of the reconstruction underestimates the true depth. In a second experimental study, the influence of a pipe clamp on the thickness reconstruction is considered, representing an inspection problem with restricted access. Preliminary results have shown that the maximum defect depth is further underestimated when compared to the thickness reconstructions without the clamp. However, it is possible to detect the defect underneath the clamp for all conducted experiments.

  10. Experimental study of A0 Lamb wave tomography

    SciTech Connect

    Seher, Matthias Huthwaite, Peter Lowe, Michael Cawley, Peter

    2015-03-31

    Corrosion damage in inaccessible regions presents a significant challenge to the petrochemical industry, and determining the remaining wall thickness is important to establish the remaining service life. Guided wave tomography is one solution and involves transmitting Lamb waves through the area of interest and using the received signals to reconstruct the remaining wall thickness. This avoids the need to access all points on the surface, making the technique well suited to inspection beneath supports. For this purpose a tomography system for pipe inspections is developed using low frequency A0 Lamb waves that are excited and detected with two arrays of electromagnetic acoustic transducers (EMATs). Two different defect depths are considered with different contrasts relative to the nominal wall thickness and in a first step, the repeatability of the measurements is demonstrated. Due to the limited view array configuration, the maximum depth of the reconstruction underestimates the true depth. In a second experimental study, the influence of a pipe clamp on the thickness reconstruction is considered, representing an inspection problem with restricted access. Preliminary results have shown that the maximum defect depth is further underestimated when compared to the thickness reconstructions without the clamp. However, it is possible to detect the defect underneath the clamp for all conducted experiments.

  11. Signal processing techniques for recovering input waveforms in dispersive Lamb wave propagation

    NASA Astrophysics Data System (ADS)

    Jeong, Hyunjo

    2014-02-01

    Lamb waves are extensively used in plate-like structure inspection because of their guided nature. However, their dispersive properties often limit their use in flaw detection and other applications. Dispersion weakens and defocuses interrogating Lamb waves and makes it difficult to accurately interpret signals reflected from defects or boundaries. Time reversal (TR) processing can be applied to compensate for the effect of dispersive Lamb waves. Thus, the TR operation will enable the amplification of dispersive Lamb wave signals by signal compression in time. In this study, experiments are performed in order to examine the refocusing and recovering the initial input waveform in the long range propagation of dispersive Lamb waves in a plate. Two different time reversal processes (regular TR and reciprocal TR or inverse filtering) are tested and the experimental results are compared.

  12. Numerical and experimental investigation of nonlinear ultrasonic Lamb waves at low frequency

    NASA Astrophysics Data System (ADS)

    Zuo, Peng; Zhou, Yu; Fan, Zheng

    2016-07-01

    Nonlinear ultrasonic Lamb waves are popular to characterize the nonlinearity of materials. However, the widely used nonlinear Lamb mode suffers from two associated complications: inherent dispersive and multimode natures. To overcome these, the symmetric Lamb mode (S0) at low frequency region is explored. At the low frequency region, the S0 mode is little dispersive and easy to generate. However, the secondary mode still exists, and increases linearly for significant distance. Numerical simulations and experiments are used to validate the nonlinear features and therefore demonstrate an easy alternative for nonlinear Lamb wave applications.

  13. Lamb Wave Based Structural Health Monitoring of Aircraft Structures

    NASA Astrophysics Data System (ADS)

    Pereira da Silva, Carlos Manuel Baptista

    Structural Health Monitoring (SHM) through adequate damage detection and prediction of the remaining useful life of structures is a major area of interest in the aerospace community, where the growing maintenance costs can reduce the operational life of flight vehicles. The objective of a SHM system with an advanced diagnostic capability is to gradually replace current schedule-based maintenance tasks, where components are inspected following a pre-established number of cycles using condition-based maintenance, or are maintained prior to attaining an insufficient remaining useful life, based on specified confidence bounds. The research challenge is to obtain a reliable method for determining damage existence and respective location during its initial growth state as a component of an early warning system. In this thesis, an SHM system based on Lamb waves is proposed. A damage detection algorithm based on the comparison between the damaged structural state and a reference state has been developed. The detection algorithm, based on discrete signals correlation, was tested and improved by incorporating statistical methods and domain division techniques. Two SHM system architectures, namely the sensor network and phased array system were designed, implemented and tested. A visualization method based on the superposition of solutions obtained from a test set was implemented. Tests executed with multiple damage, representing surface and through-the-thickness holes and cracks were performed. The proposed SHM systems using Lamb waves were able to reliably detect holes of 1 mm holes in aluminum and 1.5 mm in composite plates with great confidence.

  14. Piezoelectric Wafer Active Sensors in Lamb Wave-Based Structural Health Monitoring

    NASA Astrophysics Data System (ADS)

    Yu, Lingyu; Giurgiutiu, Victor

    2012-07-01

    Recent advancements in sensors and information technologies have resulted in new methods for structural health monitoring (SHM) of the performance and deterioration of structures. The enabling element is the piezoelectric wafer active sensor (PWAS). This paper presents an introduction to PWAS transducers and their applications in Lamb wave-based SHM. We begin by reviewing the fundamentals of piezoelectric intelligent materials. Then, the mechanism of using PWAS transducers as Lamb wave transmitters and receivers is presented. PWAS interact with the host structure through the shear-lag model. Lamb wave mode tuning can be achieved by judicious combination of PWAS dimensions, frequency value, and Lamb mode characteristics. Finally, use of PWAS Lamb wave SHM for damage detection on plate-like aluminum structures is addressed. Examples of using PWAS phased array scanning, quantitative crack detection with array imaging, and quantitative corrosion detection are given.

  15. Mode separation of Lamb waves based on dispersion compensation method.

    PubMed

    Xu, Kailiang; Ta, Dean; Moilanen, Petro; Wang, Weiqi

    2012-04-01

    Ultrasonic Lamb modes typically propagate as a combination of multiple dispersive wave packets. Frequency components of each mode distribute widely in time domain due to dispersion and it is very challenging to separate individual modes by traditional signal processing methods. In the present study, a method of dispersion compensation is proposed for the purpose of mode separation. This numerical method compensates, i.e., compresses, the individual dispersive waveforms into temporal pulses, which thereby become nearly un-overlapped in time and frequency and can thus be extracted individually by rectangular time windows. It was further illustrated that the dispersion compensation also provided a method for predicting the plate thickness. Finally, based on reversibility of the numerical compensation method, an artificial dispersion technique was used to restore the original waveform of each mode from the separated compensated pulse. Performances of the compensation separation techniques were evaluated by processing synthetic and experimental signals which consisted of multiple Lamb modes with high dispersion. Individual modes were extracted with good accordance with the original waveforms and theoretical predictions. PMID:22501050

  16. Sensitivity of contact-free fiber Bragg grating sensor to ultrasonic Lamb wave

    NASA Astrophysics Data System (ADS)

    Wee, Junghyun; Hackney, Drew; Peters, Kara; Wells, Brian; Bradford, Philip

    2016-04-01

    Networks of fiber Bragg grating (FBG) sensors can serve as structural health monitoring (SHM) systems for large-scale structures based on the collection of ultrasonic waves. The demodulation of structural Lamb waves requires a high signal-to-noise ratio because Lamb waves have a low amplitude. This paper investigates the signal transfer between Lamb waves propagating in an aluminum plate collected by an optical fiber containing a FBG. The fiber is bonded to the plate at locations away from the FBG. The Lamb waves are converted into longitudinal and flexural traveling waves propagating along the optical fiber, which are then transmitted to the Bragg grating. The signal wave amplitude is measured for different distances between the bond location and the Bragg grating. Bonding the optical fiber away from the FBG location and closer to the signal source produces a significant increase in signal amplitude, here measured to be 5.1 times that of bonding the Bragg grating itself. The arrival time of the different measured wave coupling paths are also calculated theoretically, verifying the source of the measured signals. The effect of the bond length to Lamb wavelength ratio is investigated, showing a peak response as the bond length is reduced compared to the wavelength. This study demonstrates that coupling Lamb waves into guided traveling waves in an optical fiber away from the FBG increases the signal-to-noise ratio of Lamb wave detection, as compared to direct transfer of the Lamb wave to the optical fiber at the location of the FBG.

  17. Far-Field Decay of Laser-Generated, Axisymmetric Lamb Waves

    NASA Astrophysics Data System (ADS)

    Luangvilai, Kritsakorn; Jacobs, Laurence J.; Qu, Jianmin

    2004-02-01

    Ultrasonic attenuation is a combination of material losses and geometric effects. The current research quantifies the geometric effects in the far-field, where the individual modes of a Lamb wave become separated. The overall ultrasonic signal, which is a superposition of these modes, depends on geometry, source type and individual mode characteristics. This research considers the amplitude decay of Lamb waves in an isotropic plate that are generated with an ablation source. A numerical simulation is developed using normal mode expansions, and is used to calculate amplitude decay. These numerical results are verified with an experimental program that uses laser generation and detection of multi-mode, Lamb waves.

  18. Fatigue crack detection in a plate girder using Lamb waves

    NASA Astrophysics Data System (ADS)

    Greve, D. W.; Oppenheim, I. J.; Wu, Wei; Zheng, Peng

    2007-04-01

    We report on the application of wafer-type PZT transducers to the detection of flaws in steel plate girders. In these experiments one transducer is used to emit a pulse and the second receives the pulse and reflections from nearby boundaries, flaws, or discontinuities (pitch-catch mode). In this application there will typically be numerous reflections observed in the undamaged structure. A major challenge is to recognize new reflections caused by fatigue cracks in the presence of these background reflections. A laboratory specimen plate girder was fabricated at approximately half scale, 910 mm deep with an h/t ratio of 280 for the web and a b/t ratio of 16 for the flanges, and with transverse stiffeners fabricated with a web gap at the tension flange. Two wafer-type transducers were mounted on the web approximately 175 mm from the crack location, one on each side of the stiffener. The transducers were operated in pitch-catch mode, excited by a windowed sinusoid to create a narrowband transient excitation. The transducer location relative to the crack corresponded to a total included angle of roughly 30 degrees in the path reflecting from the crack. Cyclic loading was applied to develop a distortion-induced fatigue crack in the web at the web gap location. After appearance of the crack, ultrasonic measurements were performed at a range of center frequencies below the cutoff frequency of the A1 Lamb wave mode. Subsequently the crack was extended mechanically to simulate crack growth under primary longitudinal (bending) stress and the measurements were repeated. Direct differencing of the signals showed arrivals at times corresponding to reflection from the crack location, growing in amplitude as the crack was lengthened mechanically. These results demonstrate the utility of Lamb waves for crack detection even in the presence of numerous background reflections.

  19. ANALYTICAL SOLUTION FOR WAVES IN PLANETS WITH ATMOSPHERIC SUPERROTATION. II. LAMB, SURFACE, AND CENTRIFUGAL WAVES

    SciTech Connect

    Peralta, J.; López-Valverde, M. A.; Imamura, T.; Read, P. L.; Luz, D.; Piccialli, A.

    2014-07-01

    This paper is the second in a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting with the primitive equations for a cyclostrophic regime, we have deduced the analytical solution for the possible waves, simultaneously including the effect of the metric terms for the centrifugal force and the meridional shear of the background wind. In those cases where the conditions for the method of the multiple scales in height are met, these wave solutions are also valid when vertical shear of the background wind is present. A total of six types of waves have been found and their properties were characterized in terms of the corresponding dispersion relations and wave structures. In this second part, we study the waves' solutions when several atmospheric approximations are applied: Lamb, surface, and centrifugal waves. Lamb and surface waves are found to be quite similar to those in a geostrophic regime. By contrast, centrifugal waves turn out to be a special case of Rossby waves that arise in atmospheres in cyclostrophic balance. Finally, we use our results to identify the nature of the waves behind atmospheric periodicities found in polar and lower latitudes of Venus's atmosphere.

  20. Analytical Solution for Waves in Planets with Atmospheric Superrotation. II. Lamb, Surface, and Centrifugal Waves

    NASA Astrophysics Data System (ADS)

    Peralta, J.; Imamura, T.; Read, P. L.; Luz, D.; Piccialli, A.; López-Valverde, M. A.

    2014-07-01

    This paper is the second in a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting with the primitive equations for a cyclostrophic regime, we have deduced the analytical solution for the possible waves, simultaneously including the effect of the metric terms for the centrifugal force and the meridional shear of the background wind. In those cases where the conditions for the method of the multiple scales in height are met, these wave solutions are also valid when vertical shear of the background wind is present. A total of six types of waves have been found and their properties were characterized in terms of the corresponding dispersion relations and wave structures. In this second part, we study the waves' solutions when several atmospheric approximations are applied: Lamb, surface, and centrifugal waves. Lamb and surface waves are found to be quite similar to those in a geostrophic regime. By contrast, centrifugal waves turn out to be a special case of Rossby waves that arise in atmospheres in cyclostrophic balance. Finally, we use our results to identify the nature of the waves behind atmospheric periodicities found in polar and lower latitudes of Venus's atmosphere.

  1. Electromagnetomechanical elastodynamic model for Lamb wave damage quantification in composites

    NASA Astrophysics Data System (ADS)

    Borkowski, Luke; Chattopadhyay, Aditi

    2014-03-01

    Physics-based wave propagation computational models play a key role in structural health monitoring (SHM) and the development of improved damage quantification methodologies. Guided waves (GWs), such as Lamb waves, provide the capability to monitor large plate-like aerospace structures with limited actuators and sensors and are sensitive to small scale damage; however due to the complex nature of GWs, accurate and efficient computation tools are necessary to investigate the mechanisms responsible for dispersion, coupling, and interaction with damage. In this paper, the local interaction simulation approach (LISA) coupled with the sharp interface model (SIM) solution methodology is used to solve the fully coupled electro-magneto-mechanical elastodynamic equations for the piezoelectric and piezomagnetic actuation and sensing of GWs in fiber reinforced composite material systems. The final framework provides the full three-dimensional displacement as well as electrical and magnetic potential fields for arbitrary plate and transducer geometries and excitation waveform and frequency. The model is validated experimentally and proven computationally efficient for a laminated composite plate. Studies are performed with surface bonded piezoelectric and embedded piezomagnetic sensors to gain insight into the physics of experimental techniques used for SHM. The symmetric collocation of piezoelectric actuators is modeled to demonstrate mode suppression in laminated composites for the purpose of damage detection. The effect of delamination and damage (i.e., matrix cracking) on the GW propagation is demonstrated and quantified. The developed model provides a valuable tool for the improvement of SHM techniques due to its proven accuracy and computational efficiency.

  2. Dispersion of Lamb waves in a honeycomb composite sandwich panel.

    PubMed

    Baid, Harsh; Schaal, Christoph; Samajder, Himadri; Mal, Ajit

    2015-02-01

    Composite materials are increasingly being used in advanced aircraft and aerospace structures. Despite their many advantages, composites are often susceptible to hidden damages that may occur during manufacturing and/or service of the structure. Therefore, safe operation of composite structures requires careful monitoring of the initiation and growth of such defects. Ultrasonic methods using guided waves offer a reliable and cost effective method for defects monitoring in advanced structures due to their long propagation range and their sensitivity to defects in their propagation path. In this paper, some of the useful properties of guided Lamb type waves are investigated, using analytical, numerical and experimental methods, in an effort to provide the knowledge base required for the development of viable structural health monitoring systems for composite structures. The laboratory experiments involve a pitch-catch method in which a pair of movable transducers is placed on the outside surface of the structure for generating and recording the wave signals. The specific cases considered include an aluminum plate, a woven composite laminate and an aluminum honeycomb sandwich panel. The agreement between experimental, numerical and theoretical results are shown to be excellent in certain frequency ranges, providing a guidance for the design of effective inspection systems. PMID:25287973

  3. On Lamb wave propagation from small surface explosions in the atmospheric boundary layer

    SciTech Connect

    ReVelle, D.O.; Kulichkov, S.N.

    1998-12-31

    The problem of Lamb waves propagation from small explosions in the atmospheric boundary layer are discussed. The results of lamb waves registrations from surface explosions with yields varied from 3 tons up to a few hundred tons (TNT equivalent) are presented. The source-receiver distances varied from 20 km up to 310 km. Most of the explosions were conducted during the evening and early morning hours when strong near-surface temperature and wind inversions existed. The corresponding profiles of effective sound velocity are presented. Some of the explosions had been realized with 15 minute intervals between them when morning inversion being destroyed. Corresponding transformation of Lamb waves was observed. The Korteveg-de Vrize equation to explain experimental data on Lamb waves propagation along earth surface is used.

  4. Finite element approach analysis for characteristics of electromagnetic acoustic Lamb wave

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoming; Li, Songsong

    2016-04-01

    The electromagnetic acoustic Lamb wave, with the advantages of quickly detecting the defect and sensitivity to the defects, is widely used in non-destructive testing of thin sheet. In this paper, the directivity of sound field, Phase velocity, group velocity and particle displacement amplitude of Lamb wave are study based on finite element analysis method. The results show that, for 1mm aluminum, when the excitation frequency 0.64MHz, the displacement amplitude of A0 mode is minimum, and the displacement amplitude S0 mode is largest. Appropriate to increase the displacement amplitude of a mode, while reducing displacement amplitude of another mode, to achieve the excitation of a single mode Lamb wave. It is helpful to the Optimization of transducer parameters, the choice of Lamb wave modes and providing optimal excitation frequency.

  5. Creep Damage Evaluation of Titanium Alloy Using Nonlinear Ultrasonic Lamb Waves

    NASA Astrophysics Data System (ADS)

    Xiang, Yan-Xun; Deng, Ming-Xi; Xuan, Fu-Zhen; Chen, Hu; Chen, Ding-Yue

    2012-10-01

    The creep damage in high temperature resistant titanium alloys Ti60 is measured using the nonlinear effect of an ultrasonic Lamb wave. The results show that the normalised acoustic nonlinearity of a Lamb wave exhibits a variation of the “increase-decrease" tendency as a function of the creep damage. The influence of microstructure evolution on the nonlinear Lamb wave propagation has been analyzed based on metallographic studies, which reveal that the normalised acoustic nonlinearity increases due to a rising of the precipitation volume fraction and the dislocation density in the early stage, and it decreases as a combined result of dislocation change and micro-void initiation in the material. The nonlinear Lamb wave exhibits the potential for the assessment of the remaining creep life in metals.

  6. Numerical simulation and experimental validation of Lamb wave propagation behavior in composite plates

    NASA Astrophysics Data System (ADS)

    Kim, Sungwon; Uprety, Bibhisha; Mathews, V. John; Adams, Daniel O.

    2015-03-01

    Structural Health Monitoring (SHM) based on Acoustic Emission (AE) is dependent on both the sensors to detect an impact event as well as an algorithm to determine the impact location. The propagation of Lamb waves produced by an impact event in thin composite structures is affected by several unique aspects including material anisotropy, ply orientations, and geometric discontinuities within the structure. The development of accurate numerical models of Lamb wave propagation has important benefits towards the development of AE-based SHM systems for impact location estimation. Currently, many impact location algorithms utilize the time of arrival or velocities of Lamb waves. Therefore the numerical prediction of characteristic wave velocities is of great interest. Additionally, the propagation of the initial symmetric (S0) and asymmetric (A0) wave modes is important, as these wave modes are used for time of arrival estimation. In this investigation, finite element analyses were performed to investigate aspects of Lamb wave propagation in composite plates with active signal excitation. A comparative evaluation of two three-dimensional modeling approaches was performed, with emphasis placed on the propagation and velocity of both the S0 and A0 wave modes. Results from numerical simulations are compared to experimental results obtained from active AE testing. Of particular interest is the directional dependence of Lamb waves in quasi-isotropic carbon/epoxy composite plates. Numerical and experimental results suggest that although a quasi-isotropic composite plate may have the same effective elastic modulus in all in-plane directions, the Lamb wave velocity may have some directional dependence. Further numerical analyses were performed to investigate Lamb wave propagation associated with circular cutouts in composite plates.

  7. Modeling of three-dimensional Lamb wave propagation excited by laser pulses.

    PubMed

    Liu, Wenyang; Hong, Jung-Wuk

    2015-01-01

    As a type of broadband source of ultrasonic guided waves, laser pulses can be used to launch all modes of interests. In this paper, Lamb waves are excited by imposing heat flux mimicking the supply of the heat from laser pulses, and effects by defects on the received Lamb waves in a plate are investigated by means of the finite element method. In order to alleviate the heavy computational cost in solving the coupled finite element equations, a sub-regioning scheme is employed, and it reduces the computational cost significantly. A comparison of Lamb waves generated by unfocused and line-focused laser sources is conducted. To validate numerical simulations, the group velocity of A0 mode is calculated based on the received signal by using the wavelet transform. The result of A0 mode group velocity is compared with the solution of Rayleigh-Lamb equations, and close agreement is observed. Lamb waves in a plate with defects of different lengths are examined next. The out-of-plane displacement in the plate with a defect is compared with the displacement in the plate without defects, and the wavelet transform is used to determine the arrival times of Lamb waves traveling at the A0 mode group velocity. A strong correlation is observed between the extent of defects and the magnitude of wavelet coefficients. PMID:25109827

  8. Lamb wave propagation in Z-pin reinforced co-cured composite pi-joints

    NASA Astrophysics Data System (ADS)

    Swenson, Eric D.; Soni, Som R.; Kapoor, Hitesh

    2010-04-01

    This paper presents an initial study on Lamb wave propagation characteristics in z-pin reinforced, co-cured composite pi-joints for the purposes of structural health monitoring (SHM). Pi-joint test articles were designed and created to replicate a co-cured, all composite skin-spar joint found within a typical aircraft wing structure. Because pi-joints exhibit various complex damage modes, formal studies are required if SHM systems are to be developed to monitor these types of joints for potential damage. Experiments were conducted on a undamaged (healthy) and damaged test articles where Lamb waves were excited using one lead zirconate titanate (PZT) transducer. A three-dimensional (3D) scanning laser Doppler vibrometer (LDV) was used to collect high-density scans of both the in-plane and out-of-plane velocity measurements. In the damaged test article, where delamination, matrix cracking, and fiber breakage can clearly be seen, changes in both the fundamental antisymmetric A0 and symmetric S0 Lamb wave modes are apparent. In both test articles, the effects of narrow geometry, discontinuity due to the attachment of the web, and thickness has detectable effects on Lamb wave propagation. From the comparisons between Lamb waves propagating through the undamaged and damaged test articles, it is clear that damage can be detected using Lamb waves in z-pin reinforced, co-cured composite pi-joints for this case of extensive damage.

  9. Simple Dispersion Equation Based on Lamb-Wave Model for Propagating Pulsive Waves in Human Heart Wall

    NASA Astrophysics Data System (ADS)

    Bekki, Naoaki; Shintani, Seine A.

    2015-12-01

    We consider the Rayleigh-Lamb-type equation for propagating pulsive waves excited by aortic-valve closure at end-systole in the human heart wall. We theoretically investigate the transcendental dispersion equation of pulsive waves for the asymmetrical zero-order mode of the Lamb wave. We analytically find a simple dispersion equation with a universal constant for a small Lamb wavenumber. We show that the simple dispersion equation can qualitatively explain the myocardial noninvasive measurements in vivo of pulsive waves in the human heart wall. We can also consistently estimate the viscoelastic constant of the myocardium in the human heart wall using the simple dispersion equation for a small Lamb wavenumber instead of using a complex nonlinear optimization.

  10. Negative reflection of Lamb waves at a free edge: Tunable focusing and mimicking phase conjugation.

    PubMed

    Gérardin, Benoît; Laurent, Jérôme; Prada, Claire; Aubry, Alexandre

    2016-07-01

    The paper studies the interaction of Lamb waves with the free edge of a plate. The reflection coefficients of a Lamb mode at a plate free edge are calculated using a semi-analytical method, as a function of frequency and angle of incidence. The conversion between forward and backward Lamb modes is thoroughly investigated. It is shown that at the zero-group velocity (ZGV) frequency, the forward S1 Lamb mode fully converts into the backward S2b Lamb mode at normal incidence. Besides, this conversion is very efficient over most of the angular spectrum and remains dominant at frequencies just above the ZGV-point. This effect is observed experimentally on a Duralumin plate. First, the S1 Lamb mode is selectively generated using a transducer array, second the S2b mode is excited using a single circular transducer. The normal displacement field is probed with an interferometer. The free edge is shown to retro-focus the incident wave at different depths depending on the wave number mismatch between the forward and backward propagating modes. In the vicinity of the ZGV-point, wave numbers coincide and the wave is retro-reflected on the source. In this frequency range, the free edge acts as a perfect phase conjugating mirror. PMID:27475181

  11. Increasing signal amplitude in fiber Bragg grating detection of Lamb waves using remote bonding.

    PubMed

    Wee, Junghyun; Wells, Brian; Hackney, Drew; Bradford, Philip; Peters, Kara

    2016-07-20

    Networks of fiber Bragg grating (FBG) sensors can serve as structural health monitoring systems for large-scale structures based on the collection of ultrasonic waves. The demodulation of structural Lamb waves using FBG sensors requires a high signal-to-noise ratio because the Lamb waves are of low amplitudes. This paper compares the signal transfer amplitudes between two adhesive mounting configurations for an FBG to detect Lamb waves propagating in an aluminum plate: a directly bonded FBG and a remotely bonded FBG. In the directly bonded FBG case, the Lamb waves create in-plane and out-of-plane displacements, which are transferred through the adhesive bond and detected by the FBG sensor. In the remotely bonded FBG case, the Lamb waves are converted into longitudinal and flexural traveling waves in the optical fiber at the adhesive bond, which propagate through the optical fiber and are detected by the FBG sensor. A theoretical prediction of overall signal attenuation also is performed, which is the combination of material attenuation in the plate and optical fiber and attenuation due to wave spreading in the plate. The experimental results demonstrate that remote bonding of the FBG significantly increases the signal amplitude measured by the FBG. PMID:27463905

  12. Wireless system for structural health monitoring based on Lamb waves

    NASA Astrophysics Data System (ADS)

    Lieske, U.; Dietrich, A.; Schubert, L.; Frankenstein, B.

    2012-04-01

    Structural health monitoring systems are increasingly used for comprehensive fatigue tests and surveillance of large scale structures. In this paper we describe the development and validation of a wireless system for SHM application based on Lamb-waves. The system is based on a wireless sensor network and focuses especially on low power measurement, signal processing and communication. The sensor nodes were realized by compact, sensor near signal processing structures containing components for analog preprocessing of acoustic signals, their digitization and network communication. The core component is a digital microprocessor ARM Cortex-M3 von STMicroelectronics, which performs the basic algorithms necessary for data acquisition synchronization and filtering. The system provides network discovery and multi-hop and self-healing mechanisms. If the distance between two communicating devices is too big for direct radio transmission, packets are routed over intermediate devices automatically. The system represents a low-power and low-cost active structural health monitoring solution. As a first application, the system was installed on a CFRP structure.

  13. Effect of precipitate-dislocation interactions on generation of nonlinear Lamb waves in creep-damaged metallic alloys

    NASA Astrophysics Data System (ADS)

    Xiang, Yanxun; Deng, Mingxi; Xuan, Fu-Zhen; Liu, Chang-Jun

    2012-05-01

    An analytical model is presented for the effect of the interactions of dislocations with precipitate coherency strains on the generation of second-harmonic of Lamb waves in metallic alloys. The cumulative second-harmonic of Lamb wave propagation is shown to depend dominantly on the dislocation density, pinning dislocation length, internal stress due to the coherency strain, volume fraction of the precipitates, and the phase matching degree between the primary Lamb wave and the double frequency Lamb wave (DFLW). Experiments were carried out to introduce controlled levels of creep-induced damage to determine the nonlinear response of Lamb waves in titanium alloy Ti60 plates. A like mountain-shape change in the normalized acoustic nonlinearity of Lamb wave versus the creep loading time has been observed. Microscopic image analyses were performed to interpret the variation of the measured acoustic nonlinearity and to obtain the microstructure parameters of the Ti60 specimens with different creep damages. The analytical model was applied to these creep damaged Ti60 specimens, which revealed a good accordance with the measured results of the nonlinear Lamb waves. These results indicate that the acoustic nonlinearity of Lamb wave increases due to the rising of the precipitation volume fraction and the dislocation density in the early stage, and it decreases as a combined result of the reduction of the precipitation volume fraction and the dislocation density and the increasing mismatch of the phase velocity between the primary Lamb wave and the DFLW after a further creep loading.

  14. Interaction of Lamb waves with geometric discontinuities: An analytical approach compared with FEM

    NASA Astrophysics Data System (ADS)

    Poddar, Banibrata; Giurgiutiu, Victor

    2015-03-01

    The non-destructive testing of materials can be conducted by various techniques. Amongst these, method based on ultrasonic waves is one of the most common one. Of these ultrasonic waves Lamb waves are of particular interest for the inspection of large structures for various reasons. Scattering of Lamb waves from flaws has generated a considerable amount of research over last couple of decades. Most of the work has been done using computational tools like Finite Element Methods and experimental technique. In this paper an analytical approach is presented to develop a fundamental understanding of the scattering of Lamb waves from geometric discontinuities in 2 dimensions. We have considered simplest of all geometric discontinuity - a step, as this fundamental understanding can easily be extended to corrosion or crack.

  15. Experimental validation of analytical model for Lamb wave interaction with geometric discontinuity

    NASA Astrophysics Data System (ADS)

    Poddar, Banibrata; Giurgiutiu, Victor

    2015-04-01

    Non-destructive testing methods based on ultrasonic waves are one of the most popular methods for damage detection in structures. Of these ultrasonic waves Lamb waves are of particular interest for the inspection of large structures for various reasons. Therefore scattering of Lamb waves from flaws has generated a considerable amount of research over last couple of decades. Most of the work has been done using computational tools like Finite Element Methods and experimental technique. In this paper an analytical approach is presented to develop a fundamental understanding of the scattering of Lamb waves from geometric discontinuities in 2 dimensions. We have considered simplest of all geometric discontinuity - a step, as this fundamental understanding can easily be extended to corrosion or crack.

  16. Methods of localization of Lamb wave sources on thin plates

    NASA Astrophysics Data System (ADS)

    Turkaya, Semih; Toussaint, Renaud; Kvalheim Eriksen, Fredrik; Daniel, Guillaume; Grude Flekkøy, Eirik; Jørgen Måløy, Knut

    2015-04-01

    Signal localization techniques are ubiquitous in both industry and academic communities. We propose a new localization method on plates which is based on energy amplitude attenuation and inverted source amplitude comparison. This inversion is tested on synthetic data using Lamb wave propagation direct model and on experimental dataset (recorded with 4 Brüel & Kjær Type 4374 miniature piezoelectric shock accelerometers (1-26 kHz frequency range)). We compare the performance of the technique to the classical source localization algorithms, arrival time localization, time reversal localization, localization based on energy amplitude. Furthermore, we measure and compare the accuracy of these techniques as function of sampling rate, dynamic range, geometry, Signal to Noise Ratio, and we show that this very versatile technique works better than classical ones over the sampling rates 100kHz - 1MHz. Experimental phase consists of a glass plate having dimensions of 80cmx40cm with a thickness of 1cm. Generated signals due to a wooden hammer hit or a steel ball hit are captured by sensors placed on the plate on different locations with the mentioned sensors. Numerical simulations are done using dispersive far field approximation of plate waves. Signals are generated using a hertzian loading over the plate. Using imaginary sources outside the plate boundaries the effect of reflections is also included. This proposed method, can be modified to be implemented on 3d environments, monitor industrial activities (e.g boreholes drilling/production activities) or natural brittle systems (e.g earthquakes, volcanoes, avalanches).

  17. Phase and group velocities for Lamb waves in DOP-26 iridium alloy sheet

    SciTech Connect

    Simpson, W.A.; McGuire, D.J.

    1994-07-01

    The relatively coarse grain structure of iridium weldments limits the ultrasonic inspection of these structures to frequencies in the low megahertz range. As the material thickness is nominally 0.635 mm for clad vent set capsules, the low frequencies involved necessarily entail the generation of Lamb waves m the specimen. These waves are, of course, dispersive and detailed knowledge of both the phase and group velocities is required in order to determine accurately the location of flaws detected using Lamb waves. Purpose of this study is to elucidate the behavior of Lamb waves propagating in the capsule alloy and to quantify the velocities so that accurate flaw location is ensured. We describe a numerical technique for computing the phase velocities of Lamb waves (or of any other type of guided wave) and derive the group velocities from this information. A frequency-domain method is described for measuring group velocity when multiple Lamb modes are present and mutually interfering in the time domain, and experimental confirmation of the group velocity is presented for the capsule material.

  18. Non-contact ultrasonic technique for Lamb wave characterization in composite plates.

    PubMed

    Harb, M S; Yuan, F G

    2016-01-01

    A fully non-contact single-sided air-coupled and laser ultrasonic non-destructive system based on the generation and detection of Lamb waves is implemented for the characterization of A0 Lamb wave mode dispersion in a composite plate. An air-coupled transducer (ACT) radiates acoustic pressure on the surface of the composite and generates Lamb waves within the structure. The out-of-plane velocity of the propagating wave is measured using a laser Doppler vibrometer (LDV). In this study, the non-contact automated system focuses on measuring A0 mode frequency-wavenumber, phase velocity dispersion curves using Snell's law and group velocity dispersion curves using Morlet wavelet transform (MWT) based on time-of-flight along different wave propagation directions. It is theoretically demonstrated that Snell's law represents a direct link between the phase velocity of the generated Lamb wave mode and the coincidence angle of the ACT. Using Snell's law and MWT, the former three dispersion curves of the A0 mode are easily and promptly generated from a set of measurements obtained from a rapid ACT angle scan experiment. In addition, the phase velocity and group velocity polar characteristic wave curves are also computed to analyze experimentally the angular dependency of Lamb wave propagation. In comparison with the results from the theory, it is confirmed that using the ACT/LDV system and implementing simple Snell's law method is highly sensitive and effective in characterizing the dispersion curves of Lamb waves in composite structures as well as its angular dependency. PMID:26385842

  19. Laser generation of Lamb waves for defect detection: experimental methods and finite element modeling.

    PubMed

    Burrows, Susan E; Dutton, Ben; Dixon, Steve

    2012-01-01

    The propagation of Lamb waves generated by a pulsed laser beam in an aluminum sheet is modeled using finite element analysis, and the interaction with defects is studied and compared to experimental results. The ultrasonic Lamb waves are detected by an electromagnetic acoustic transducer (EMAT). The frequency content of the received wave is shown to be enhanced when the generation point is situated directly over the defect in both the modeled and experimental cases. Time-frequency analysis using a Wigner transform has enabled individual modes to be identified. PMID:22293738

  20. Nonlinear effect of debonding of wafer type piezoelectric actuator on the behaviour of Lamb wave

    NASA Astrophysics Data System (ADS)

    Yelve, Nitesh P.; Mitra, Mira; Mujumdar, P. M.

    2014-03-01

    In Lamb wave based techniques for damage detection, Piezoelectric Wafer (PW) transducers are often used for actuating Lamb wave. They offer advantages such as portability and, cost effectiveness. However, because of prolonged use, excessive voltage supply, or improper bonding onto the host structure, these PW actuators may get partially debonded from the host structure. In this paper, the nonlinear effect of this debonding on the behavior of Lamb wave manifested in the form of higher harmonics, is studied both experimentally and through Finite Element (FE) simulation. Augmented Lagrangian algorithm is used in FE simulation to solve the contact problem at the breathing debond. Three higher harmonics are observed in the experiments and also in the FE simulation. Morlet wavelet transform is implemented in the study for time-frequency analysis and the results are reported in the paper. Nonlinearity parameter β obtained from fundamental and second harmonics in the experiments and the simulation, is found to be increasing with increase in the debonding area. This shows that actuator debonding produces contact nonlinearity and thereby induces higher harmonics in the Lamb wave. Therefore, in damage detection using Lamb wave based nonlinear techniques, the higher harmonics produced may get influenced by the false higher harmonics produced by actuator debonding, leading to incorrect results. Also these false higher harmonics resulting from actuator debonding may show illusory presence of defect in a pristine material, if bonding of the actuator is not taken care of properly.

  1. Lamb Wave Line Sensing for Crack Detection in a Welded Stiffener

    PubMed Central

    An, Yun-Kyu; Kim, Jae Hong; Yim, Hong Jae

    2014-01-01

    This paper proposes a novel Lamb wave line sensing technique for crack detection in a welded stiffener. The proposed technique overcomes one of the biggest technical challenges of Lamb wave crack detection for real structure applications: crack-induced Lamb waves are often mixed with multiple reflections from complex waveguides. In particular, crack detection in a welded joint, one of the structural hot spots due to stress concentration, is accompanied by reflections from the welded joint as well as a crack. Extracting and highlighting crack-induced Lamb wave modes from Lamb wave responses measured at multi-spatial points along a single line can be accomplished through a frequency-wavenumber domain analysis. The advantages of the proposed technique enable us not only to enhance the crack detectability in the welded joint but also to minimize false alarms caused by environmental and operational variations by avoiding the direct comparison with the baseline data previously accumulated from the pristine condition of a target structure. The proposed technique is experimentally and numerically validated in vertically stiffened metallic structures, revealing that it successfully identifies and localizes subsurface cracks, regardless of the coexistence with the vertical stiffener. PMID:25046014

  2. Propagation of Lamb waves in one-dimensional radial phononic crystal plates with periodic corrugations

    NASA Astrophysics Data System (ADS)

    Li, Yinggang; Chen, Tianning; Wang, Xiaopeng; Yu, Kunpeng; Chen, Weihua

    2014-02-01

    In this paper, we theoretically investigate the propagation characteristics of Lamb waves in one-dimensional radial phononic crystal plates with periodic corrugations. The dispersion relations, the power transmission spectra, and the displacement fields of the eigenmodes are calculated by using the finite element method based on two-dimensional axial symmetry models in cylindrical coordinates. The axial symmetry model is validated by three-dimensional finite element model in rectangular coordinates. The effects of the geometrical parameters on the band gaps are further explored numerically. Numerical results show that several complete band gaps with a variable bandwidth exist for Lamb waves in the proposed structures. The formation mechanism of opening the acoustic band gaps is attributed to the coupling between the Lamb modes and the corrugation mode. The band gaps are significantly dependent upon the geometrical parameters such as the corrugation height, the corrugation width, and the plate thickness. Significantly, as the increase of corrugation height, band width shifts, new band gaps appear, the bands become flat, and the corrugation mode plays a more prominent role in the opening of Lamb wave band gaps. These properties of Lamb waves in the radial phononic crystal plates can potentially be applied to optimize band gaps, generate filters, and design acoustic devices.

  3. A hybrid method based upon nonlinear Lamb wave response for locating a delamination in composite laminates.

    PubMed

    Yelve, Nitesh P; Mitra, Mira; Mujumdar, P M; Ramadas, C

    2016-08-01

    A new hybrid method based upon nonlinear Lamb wave response in time and frequency domains is introduced to locate a delamination in composite laminates. In Lamb wave based nonlinear method, the presence of damage is shown by the appearance of higher harmonics in the Lamb wave response. The proposed method not only uses this spectral information but also the corresponding temporal response data, for locating the delamination. Thus, the method is termed as a hybrid method. The paper includes formulation of the method and its application to locate a Barely Visible Impact Damage (BVID) induced delamination in a Carbon Fiber Reinforced Polymer (CFRP) laminate. The method gives the damage location fairly well. It is a baseline free method, as it does not need data from the pristine specimen. PMID:27115575

  4. Ultrasonic Waveguide Sensor Using a Leaky Lamb Wave for Under-Sodium Viewing

    NASA Astrophysics Data System (ADS)

    Joo, Young-Sang; Lee, Jae-Han

    2010-02-01

    A plate-type ultrasonic waveguide sensor using a leaky Lamb wave has been developed for the under-sodium viewing of a reactor core and in-vessel structures of a sodium-cooled fast reactor (SFR). An A0 Lamb wave mode is utilized in the waveguide sensor for the single mode generation and the effective radiation capability in a fluid. A radiation beam steering technique is presented which is achieved by the frequency tuning of the excitation pulse in the frequency range of the A0 Lamb wave mode which the group velocity is not dispersive and the phase velocity is dispersive. The long distance propagation ability and C-scan imaging performance have been demonstrated successfully by experimental feasibility tests of the waveguide sensor.

  5. A study of helical Lamb wave propagation on two hollow cylinders with imperfect contact conditions

    NASA Astrophysics Data System (ADS)

    Balvantin, A.; Baltazar, A.; Kim, J.-Y.

    2013-01-01

    The effects of varying interfacial conditions between two contacting hollow cylinders on the propagation of helical Lamb waves are studied. Experiments were carried out on two aluminum hollow cylinders (114 mm in outer-diameter and 6 mm of wall thickness) axially loaded by a horizontal press to control contact interfacial stiffness. An ultrasonic measurement setup using broadband transducers, with semispherical contact probes coupled to the cylinders surface, in a pitchcatch configuration is presented. Time-frequency representation (TFR) is employed to accurately perform mode identification of ultrasonic captured signals. The effect of different interfacial contact conditions in mechanically joined cylinders into propagation parameters of helical Lamb waves is studied. Finally, a comparison of sensitivity, between Lamb waves in straight and helical propagating paths, under different interfacial conditions is presented.

  6. Experimental demonstration of ordered and disordered multiresonant metamaterials for lamb waves.

    PubMed

    Rupin, Matthieu; Lemoult, Fabrice; Lerosey, Geoffroy; Roux, Philippe

    2014-06-13

    We demonstrate the experimental realization of a multiresonant metamaterial for Lamb waves, i.e., elastic waves propagating in plates. The metamaterial effect comes from the resonances of long aluminum rods that are attached to an aluminum plate. Using time-dependent measurements, we experimentally prove that this metamaterial exhibits wide band gaps as well as sub- and suprawavelength modes for both a periodic and a random arrangement of the resonators. The dispersion curve inside the metamaterial is predicted through hybridizations between flexural and compressional resonances in the rods and slow and fast Lamb modes in the plate. We finally underline how the various degrees of freedom of such system paves the way to the design of metamaterials for the control of Lamb waves in unprecedented ways. PMID:24972210

  7. Baseline Signal Reconstruction for Temperature Compensation in Lamb Wave-Based Damage Detection.

    PubMed

    Liu, Guoqiang; Xiao, Yingchun; Zhang, Hua; Ren, Gexue

    2016-01-01

    Temperature variations have significant effects on propagation of Lamb wave and therefore can severely limit the damage detection for Lamb wave. In order to mitigate the temperature effect, a temperature compensation method based on baseline signal reconstruction is developed for Lamb wave-based damage detection. The method is a reconstruction of a baseline signal at the temperature of current signal. In other words, it compensates the baseline signal to the temperature of current signal. The Hilbert transform is used to compensate the phase of baseline signal. The Orthogonal matching pursuit (OMP) is used to compensate the amplitude of baseline signal. Experiments were conducted on two composite panels to validate the effectiveness of the proposed method. Results show that the proposed method could effectively work for temperature intervals of at least 18 °C with the baseline signal temperature as the center, and can be applied to the actual damage detection. PMID:27529245

  8. Interface-guided mode of Lamb waves in a two-dimensional phononic crystal plate

    NASA Astrophysics Data System (ADS)

    Huang, Ping-Ping; Yao, Yuan-Wei; Wu, Fu-Gen; Zhang, Xin; Li, Jing; Hu, Ai-Zhen

    2015-05-01

    We investigate the interface-guided mode of Lamb waves in a phononic crystal heterostructures plate, which is composed of two different semi-infinite phononic crystal (PC) plates. The interface-guided modes of the Lamb wave can be obtained by the lateral lattice slipping or by the interface longitudinal gliding. Significantly, it is observed that the condition to generate the interface-guided modes of the Lamb wave is more demanding than that of the studied fluid-fluid system. The interface-guided modes are strongly affected not only by the relative movement of the two semi-infinite PCs but also by the thickness of the PC plate. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374068 and 11374066), the Science & Technology Star of Zhujiang Foundation of Guangzhou, China (Grant No. 2011J2200013), and the Natural Science Foundation of Guangdong, China (Grant No. S2012020010885).

  9. Damage imaging using Lamb waves for SHM applications

    NASA Astrophysics Data System (ADS)

    Stepinski, Tadeusz; Ambroziński, Łukasz; Uhl, Tadeusz

    2015-03-01

    2-D ultrasonic arrays, due to their beam-steering capability and all azimuth angle coverage are a very promising tool for the inspection of plate-like structures using Lamb waves (LW). Contrary to the classical linear phased arrays (PAs) the 2D arrays enable unequivocal defect localization and they are even capable of mode selectivity of the received LWs . Recently, it has been shown that multistatic synthetic focusing (SF) algorithms applied for 2D arrays are much more effective than the classical phase array mode commonly used in NDT. The multistatic SF assumes multiple transmissions of elements in a transmitting aperture and off-line processing of the data acquired by a receiving aperture. In the simplest implementation of the technique, only a single multiplexed input and a number of output channels are required, which results in significant hardware simplification compared with the PA systems. On the one hand implementation of the multistatic SF to 2D arrays creates additional degrees of freedom during the design of the array topology, which complicates the array design process. On the other hand, it enables designing sparse arrays with performance similar to that of the fully populated dense arrays. In this paper we present a general systematic approach to the design and optimization of imaging systems based on the 2D array operating in the multistatic mode. We start from presenting principles of the SF schemes applied to LW imaging. Then, we outline the coarray concept and demonstrate how it can be used for reducing number of elements of the 2D arrays. Finally, efficient tools for the investigation and experimental verification of the designed 2D array prototypes are presented. The first step in the investigation is theoretical evaluation performed using frequency-dependent structure transfer function (STF), which enables approximate simulation of an array excited with a tone-burst in a dispersive medium. Finally, we show how scanning laser vibrometer

  10. Damage imaging using Lamb waves for SHM applications

    SciTech Connect

    Stepinski, Tadeusz Ambroziński, Łukasz Uhl, Tadeusz

    2015-03-31

    2-D ultrasonic arrays, due to their beam-steering capability and all azimuth angle coverage are a very promising tool for the inspection of plate-like structures using Lamb waves (LW). Contrary to the classical linear phased arrays (PAs) the 2D arrays enable unequivocal defect localization and they are even capable of mode selectivity of the received LWs . Recently, it has been shown that multistatic synthetic focusing (SF) algorithms applied for 2D arrays are much more effective than the classical phase array mode commonly used in NDT. The multistatic SF assumes multiple transmissions of elements in a transmitting aperture and off-line processing of the data acquired by a receiving aperture. In the simplest implementation of the technique, only a single multiplexed input and a number of output channels are required, which results in significant hardware simplification compared with the PA systems. On the one hand implementation of the multistatic SF to 2D arrays creates additional degrees of freedom during the design of the array topology, which complicates the array design process. On the other hand, it enables designing sparse arrays with performance similar to that of the fully populated dense arrays. In this paper we present a general systematic approach to the design and optimization of imaging systems based on the 2D array operating in the multistatic mode. We start from presenting principles of the SF schemes applied to LW imaging. Then, we outline the coarray concept and demonstrate how it can be used for reducing number of elements of the 2D arrays. Finally, efficient tools for the investigation and experimental verification of the designed 2D array prototypes are presented. The first step in the investigation is theoretical evaluation performed using frequency-dependent structure transfer function (STF), which enables approximate simulation of an array excited with a tone-burst in a dispersive medium. Finally, we show how scanning laser vibrometer

  11. Intelligent feature selection techniques for pattern classification of Lamb wave signals

    SciTech Connect

    Hinders, Mark K.; Miller, Corey A.

    2014-02-18

    Lamb wave interaction with flaws is a complex, three-dimensional phenomenon, which often frustrates signal interpretation schemes based on mode arrival time shifts predicted by dispersion curves. As the flaw severity increases, scattering and mode conversion effects will often dominate the time-domain signals, obscuring available information about flaws because multiple modes may arrive on top of each other. Even for idealized flaw geometries the scattering and mode conversion behavior of Lamb waves is very complex. Here, multi-mode Lamb waves in a metal plate are propagated across a rectangular flat-bottom hole in a sequence of pitch-catch measurements corresponding to the double crosshole tomography geometry. The flaw is sequentially deepened, with the Lamb wave measurements repeated at each flaw depth. Lamb wave tomography reconstructions are used to identify which waveforms have interacted with the flaw and thereby carry information about its depth. Multiple features are extracted from each of the Lamb wave signals using wavelets, which are then fed to statistical pattern classification algorithms that identify flaw severity. In order to achieve the highest classification accuracy, an optimal feature space is required but it’s never known a priori which features are going to be best. For structural health monitoring we make use of the fact that physical flaws, such as corrosion, will only increase over time. This allows us to identify feature vectors which are topologically well-behaved by requiring that sequential classes “line up” in feature vector space. An intelligent feature selection routine is illustrated that identifies favorable class distributions in multi-dimensional feature spaces using computational homology theory. Betti numbers and formal classification accuracies are calculated for each feature space subset to establish a correlation between the topology of the class distribution and the corresponding classification accuracy.

  12. Intelligent feature selection techniques for pattern classification of Lamb wave signals

    NASA Astrophysics Data System (ADS)

    Hinders, Mark K.; Miller, Corey A.

    2014-02-01

    Lamb wave interaction with flaws is a complex, three-dimensional phenomenon, which often frustrates signal interpretation schemes based on mode arrival time shifts predicted by dispersion curves. As the flaw severity increases, scattering and mode conversion effects will often dominate the time-domain signals, obscuring available information about flaws because multiple modes may arrive on top of each other. Even for idealized flaw geometries the scattering and mode conversion behavior of Lamb waves is very complex. Here, multi-mode Lamb waves in a metal plate are propagated across a rectangular flat-bottom hole in a sequence of pitch-catch measurements corresponding to the double crosshole tomography geometry. The flaw is sequentially deepened, with the Lamb wave measurements repeated at each flaw depth. Lamb wave tomography reconstructions are used to identify which waveforms have interacted with the flaw and thereby carry information about its depth. Multiple features are extracted from each of the Lamb wave signals using wavelets, which are then fed to statistical pattern classification algorithms that identify flaw severity. In order to achieve the highest classification accuracy, an optimal feature space is required but it's never known a priori which features are going to be best. For structural health monitoring we make use of the fact that physical flaws, such as corrosion, will only increase over time. This allows us to identify feature vectors which are topologically well-behaved by requiring that sequential classes "line up" in feature vector space. An intelligent feature selection routine is illustrated that identifies favorable class distributions in multi-dimensional feature spaces using computational homology theory. Betti numbers and formal classification accuracies are calculated for each feature space subset to establish a correlation between the topology of the class distribution and the corresponding classification accuracy.

  13. Time-frequency characterization of lamb waves for material evaluation and damage inspection of plates

    NASA Astrophysics Data System (ADS)

    Frank Pai, P.; Deng, Haoguang; Sundaresan, Mannur J.

    2015-10-01

    Guided wave-based technique is one major approach for damage inspection of structures. To detect a small damage, an elastic wave's wavelength needs to be in the order of the damage size and hence the frequency needs to be high. Unfortunately, high-frequency wave dynamics always involves complicated wave reflection, refraction and diffraction, and it is difficult to separate them in order to perform detailed examination and system identification. This paper investigates dynamic characteristics of Lamb waves in plates in order to be used for material evaluation and damage inspection of thin-walled structures. A one-dimensional finite-element modeling and analysis technique is developed for computing dispersion curves and all symmetric and antisymmetric modes of Lamb waves in isotropic and multi-layer plates. Moreover, the conjugate-pair decomposition (CPD) method is introduced for time-frequency analysis of propagating Lamb waves. Results show that, under a k-cycle sine-burst excitation at a plate's edge, the time-varying frequency of a surface point's response can reveal the Lamb wave propagating inside the plate being a symmetric or an antisymmetric mode. The frequency of the measured wave packet increases from the wave front to the trailing edge if it is a symmetric mode, and the frequency decreases from the wave front to the trailing edge if it is an antisymmetric mode. Moreover, interaction of two different wave packets results in a peak in the time-frequency curve. These characteristics can be used for accurate separation of wave packets and identification of different wave speeds to enable fast and accurate material evaluation and damage inspection. Transient finite-element analysis of Lamb waves in finite plates with crack/delamination show that k-cycle sine-burst probing waves are good agents for guided wave-based damage inspection of structures. Although crack and delamination introduce different waves into and complicate the probing wave packet, time

  14. Visualization of non-propagating Lamb wave modes for fatigue crack evaluation

    NASA Astrophysics Data System (ADS)

    An, Yun-Kyu; Sohn, Hoon

    2015-03-01

    This article develops a non-propagating Lamb wave mode (NPL) imaging technique for fatigue crack visualization. NPL has a great potential for crack evaluation in that it significantly contributes local mode amplitudes in the vicinity of a crack without spatial propagation. Such unique physical phenomenon is theoretically proven and experimentally measured through laser scanning. Although its measurement is a quite challenging work due to the fact that it is quite localized and coexists with complex propagating Lamb wave modes, a NPL filter proposed in this article overcomes the technical challenge by eliminating all propagating Lamb modes from laser scanned full Lamb wavefields. Through the NPL filtering process, only fatigue crack-induced NPLs can be measured and retained. To verify such physical observation and the corresponding NPL filter, a real micro fatigue crack is created by applying repeated tensile loading, and its detectability is tested using a surface-mounted piezoelectric transducer for generating Lamb waves and a laser Doppler vibrometer for measuring the corresponding responses. The experimental results confirm that even an invisible fatigue crack can be instantaneously visualized and effectively evaluated through the proposed NPL measurement and filtering processes.

  15. Fast and accurate analytical model to solve inverse problem in SHM using Lamb wave propagation

    NASA Astrophysics Data System (ADS)

    Poddar, Banibrata; Giurgiutiu, Victor

    2016-04-01

    Lamb wave propagation is at the center of attention of researchers for structural health monitoring of thin walled structures. This is due to the fact that Lamb wave modes are natural modes of wave propagation in these structures with long travel distances and without much attenuation. This brings the prospect of monitoring large structure with few sensors/actuators. However the problem of damage detection and identification is an "inverse problem" where we do not have the luxury to know the exact mathematical model of the system. On top of that the problem is more challenging due to the confounding factors of statistical variation of the material and geometric properties. Typically this problem may also be ill posed. Due to all these complexities the direct solution of the problem of damage detection and identification in SHM is impossible. Therefore an indirect method using the solution of the "forward problem" is popular for solving the "inverse problem". This requires a fast forward problem solver. Due to the complexities involved with the forward problem of scattering of Lamb waves from damages researchers rely primarily on numerical techniques such as FEM, BEM, etc. But these methods are slow and practically impossible to be used in structural health monitoring. We have developed a fast and accurate analytical forward problem solver for this purpose. This solver, CMEP (complex modes expansion and vector projection), can simulate scattering of Lamb waves from all types of damages in thin walled structures fast and accurately to assist the inverse problem solver.

  16. Data-driven and calibration-free Lamb wave source localization with sparse sensor arrays.

    PubMed

    Harley, Joel B; Moura, José M F

    2015-08-01

    Most Lamb wave localization techniques require that we know the wave's velocity characteristics; yet, in many practical scenarios, velocity estimates can be challenging to acquire, are unavailable, or are unreliable because of the complexity of Lamb waves. As a result, there is a significant need for new methods that can reduce a system's reliance on a priori velocity information. This paper addresses this challenge through two novel source localization methods designed for sparse sensor arrays in isotropic media. Both methods exploit the fundamental sparse structure of a Lamb wave's frequency-wavenumber representation. The first method uses sparse recovery techniques to extract velocities from calibration data. The second method uses kurtosis and the support earth mover's distance to measure the sparseness of a Lamb wave's approximate frequency-wavenumber representation. These measures are then used to locate acoustic sources with no prior calibration data. We experimentally study each method with a collection of acoustic emission data measured from a 1.22 m by 1.22 m isotropic aluminum plate. We show that both methods can achieve less than 1 cm localization error and have less systematic error than traditional time-of-arrival localization methods. PMID:26276960

  17. Locating fatigue damage using temporal signal features of nonlinear Lamb waves

    NASA Astrophysics Data System (ADS)

    Hong, Ming; Su, Zhongqing; Lu, Ye; Sohn, Hoon; Qing, Xinlin

    2015-08-01

    The temporal signal features of linear guided waves, as typified by the time-of-flight (ToF), have been exploited intensively for identifying damage, with proven effectiveness in locating gross damage in particular. Upon re-visiting the conventional, ToF-based detection philosophy, the present study extends the use of temporal signal processing to the realm of nonlinear Lamb waves, so as to reap the high sensitivity of nonlinear Lamb waves to small-scale damage (e.g., fatigue cracks), and the efficacy of temporal signal processing in locating damage. Nonlinear wave features (i.e., higher-order harmonics) are extracted using networked, miniaturized piezoelectric wafers, and reverted to the time domain for damage localization. The proposed approach circumvents the deficiencies of using Lamb wave features for evaluating undersized damage, which are either undiscernible in time-series analysis or lacking in temporal information in spectral analysis. A probabilistic imaging algorithm is introduced to supplement the approach, facilitating the presentation of identification results in an intuitive manner. Through numerical simulation and then experimental validation, two damage indices (DIs) are comparatively constructed, based, respectively, on linear and nonlinear temporal features of Lamb waves, and used to locate fatigue damage near a rivet hole of an aluminum plate. Results corroborate the feasibility and effectiveness of using temporal signal features of nonlinear Lamb waves to locate small-scale fatigue damage, with enhanced accuracy compared with linear ToF-based detection. Taking a step further, a synthesized detection strategy is formulated by amalgamating the two DIs, targeting continuous and adaptive monitoring of damage from its onset to macroscopic formation.

  18. Propagation of Lamb waves in an immersed periodically grooved plate: experimental detection of the scattered converted backward waves.

    PubMed

    Harhad, Nadia; El-Kettani, Mounsif Ech-Cherif; Djelouah, Hakim; Izbicki, Jean-Louis; Predoi, Mihai Valentin

    2014-03-01

    Guided waves propagation in immersed plates with irregular surfaces has potential application to detection and assessment of the extent, depth and pattern of the irregularity. The complexity of the problem, due to the large number of involved parameters, has limited the number of existing studies. The simplest case of irregularities of practical interest is the two-dimensional corrosion profile. Even this case is in general so complex, that one can extract several amplitude dominant periodic surfaces only by using a Fourier spectrum of the surface. Guided waves in plates, with one or both free surfaces having periodic perturbations of different shapes, have been presented in specialized literature. In this paper is studied the propagation of Lamb waves in an aluminum plate with a periodic grooved surface on only one side and immersed in water. The interaction between an incident Lamb wave and the grating gives rise to retro-converted waves. Preliminary numerical simulation by the finite element method is performed in order to obtain key parameters for the experiments. It is shown that retro-converted waves radiating into the water are detectable although their amplitudes are small. The phonon relation is verified for the leaky Lamb modes. The damping coefficients of the leaky Lamb modes in the grooved immersed plate are evaluated. PMID:24262677

  19. A flexible piezoelectric transducer design for efficient generation and reception of ultrasonic Lamb waves.

    PubMed

    Gachagan, Anthony; Hayward, Gordon; Banks, Robert

    2005-07-01

    This paper describes the development of a flexible piezoelectric transducer for the generation and detection of ultrasonic symmetrical Lamb waves in plate-like structures. This piezoplatelet transducer structure comprises an array of miniature piezoceramic plates embedded within a soft setting polymer filler material, combining the efficiency of the active piezoceramic phase with a degree of flexibility, which is a function of the platelet/polymer dimensions. For many condition-monitoring applications, the generation of ultrasonic Lamb waves is often appropriate, and this was achieved by incorporating interdigital design techniques via the transducer electrode pattern. The performance of the piezoplatelet transducer structure was evaluated using a combination of linear systems and finite-element modeling, substantiated by experimental results. Importantly, the transducer is shown to operate as an ensemble of platelets, each operating in the thickness mode and well decoupled from neighboring piezoelectric elements. Using this transducer configuration, an unimodal s1 Lamb wave, at 1.45 MHz, has been generated and detected in a 3-mm thick steel plate. Furthermore, a propagation distance of almost 1 m was recorded for s0 Lamb wave generation/detection in a fiber-reinforced composite plate. PMID:16212257

  20. Stiffness matrix determination of composite materials using lamb wave group velocity measurements

    NASA Astrophysics Data System (ADS)

    Putkis, O.; Croxford, A. J.

    2013-04-01

    The use of Lamb waves in Non-Destructive Evaluation (NDE) and Structural Health Monitoring (SHM) is gaining popularity due to their ability to travel long distances without significant attenuation, therefore offering large area inspections with a small number of sensors. The design of a Lamb-wave-based NDE/SHM system for composite materials is more complicated than for metallic materials due to the directional dependence of Lamb wave propagation characteristics such as dispersion and group velocity. Propagation parameters can be theoretically predicted from known material properties, specifically the stiffness matrix and density. However, in practice it is difficult to obtain the stiffness matrix of a particular material or structure with high accuracy, hence introducing errors in theoretical predictions and inaccuracies in the resulting propagation parameters. Measured Lamb wave phase velocities can be used to infer the stiffness matrix, but the measurements are limited to the principal directions due to the steering effect (different propagation directions of phase and corresponding group velocities). This paper proposes determination of the stiffness matrix from the measured group velocities, which can be unambiguously measured in any direction. A highly anisotropic carbon-fibre-reinforced polymer plate is chosen for the study. The influence of different stiffness matrix elements on the directional group velocity profile is investigated. Thermodynamic Simulated Annealing (TSA) is used as a tool for inverse, multi variable inference of the stiffness matrix. A good estimation is achieved for particular matrix elements.

  1. Lamb wave detection in prepreg composite materials with fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Miesen, Nick; Mizutani, Yoshihiro; Groves, Roger M.; Sinke, Jos; Benedictus, Rinze

    2011-04-01

    This paper demonstrates that existing Structural Health Monitoring (SHM) techniques have potential during the production phase in addition to their application for maintenance and for in-flight monitoring. Flaws occur during composite fabrication in industry, due to an imperfect process control and human errors. This decreases production efficiency and increases costs. In this paper, the monitoring of Lamb waves in unidirectional carbon fibre (UD-CFRP) prepreg material is demonstrated using both Fibre Bragg Gratings (FBG)s and piezolectric acoustic sensors, and that these SHM sensors may be used for flaw detection and production monitoring. The detection of Lamb waves in a one ply thick sheet of prepreg UD-CFRP material is demonstrated for an FBG sensor aligned with the carbon fibre orientation and bonded to the surface of the prepreg, Furthermore, the velocity of Lamb waves in prepreg UD-CFRP in different orientations is investigated. Finally the successful detection of a material crack in a prepreg UD-CFRP sheet using the Lamb wave detection method is demonstrated.

  2. Piezoelectric transducer embedded in a composite plate: Application to Lamb wave generation

    SciTech Connect

    Moulin, E.; Assaad, J.; Delebarre, C.; Kaczmarek, H.; Balageas, D.

    1997-09-01

    The aim of this paper is to show that Lamb waves may be effectively generated using piezoelectric transducers embedded inside a composite plate, for nondestructive evaluation and health monitoring applications. A cylindrical transducer embedded in a composite host plate is considered. The electrical impedance of the transducer alone in vacuum and then of the embedded transducer, which allows the identification of the resonance modes, have been obtained by the finite element method (FEM). Moreover, the displacement fields in the plate, which allow the identification of the types of Lamb waves, have been computed at the resonance frequencies. Comparison between the FEM results and the Lamb wave dispersion curves of the host material are in good agreement. Experimental results (electrical impedance, frequency response, and phase velocities) concerning a composite plate specimen containing the same piezoelectric transducer inside it are shown. A good agreement is generally obtained between numerical and experimental results. In addition, it has been shown that the radial mode of the embedded transducer, which has a high coupling coefficient (around 50{percent}), can be used to generate S{sub 0} Lamb waves. {copyright} {ital 1997 American Institute of Physics.}

  3. Multiple-mode Lamb wave scattering simulations using 3D elastodynamic finite integration technique.

    PubMed

    Leckey, Cara A C; Rogge, Matthew D; Miller, Corey A; Hinders, Mark K

    2012-02-01

    We have implemented three-dimensional (3D) elastodynamic finite integration technique (EFIT) simulations to model Lamb wave scattering for two flaw-types in an aircraft-grade aluminum plate, a rounded rectangle flat-bottom hole and a disbond of the same shape. The plate thickness and flaws explored in this work include frequency-thickness regions where several Lamb wave modes exist and sometimes overlap in phase and/or group velocity. For the case of the flat-bottom hole the depth was incrementally increased to explore progressive changes in multiple-mode Lamb wave scattering due to the damage. The flat-bottom hole simulation results have been compared to experimental data and are shown to provide key insight for this well-defined experimental case by explaining unexpected results in experimental waveforms. For the rounded rectangle disbond flaw, which would be difficult to implement experimentally, we found that Lamb wave behavior differed significantly from the flat-bottom hole flaw. Most of the literature in this field is restricted to low frequency-thickness regions due to difficulties in interpreting data when multiple modes exist. We found that benchmarked 3D EFIT simulations can yield an understanding of scattering behavior for these higher frequency-thickness regions and in cases that would be difficult to set up experimentally. Additionally, our results show that 2D simulations would not have been sufficient for modeling the complicated scattering that occurred. PMID:21908011

  4. Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor

    PubMed Central

    Schmitt, Martin; Olfert, Sergei; Rautenberg, Jens; Lindner, Gerhard; Henning, Bernd; Reindl, Leonhard Michael

    2013-01-01

    Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid—liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner. PMID:23447010

  5. Multi-Mode Lamb Wave Arrival Time Extraction for Improved Tomographic Reconstruction

    SciTech Connect

    Hinders, Mark K.; Hou Jidong; Leonard, Kevin R.

    2005-04-09

    An ultrasonic signal processing technique is applied to multi-mode arrival time estimation from Lamb waveforms. The basic tool is a simplified time-scale projection called a dynamic wavelet fingerprint (DWFP) which enables direct observation of the variation of features of interest in non-stationary ultrasonic signals. The DWFP technique was used to automatically detect and evaluate each candidate through-transmitted Lamb mode. The area of the dynamic wavelet fingerprint was then used as a feature to distinguish false modes caused by noise and other interference from the true modes of interest. The set of estimated arrival times were then used as inputs for tomographic reconstruction. The Lamb wave tomography images generated with these estimated arrival times were able to indicate different defects in aluminum plates.

  6. Lamb waves from airborne explosion sources: Viscous effects and comparisons to ducted acoustic arrivals

    SciTech Connect

    Revelle, D.O.; Whitaker, R.W.

    1996-12-31

    Observations of large explosions in the atmosphere at long range are dominated by a leading pulse of large amplitude and long period that is often followed by a series of higher frequency impulses usually of smaller amplitude. This description can be interpreted using linearized acoustic-gravity wave theory in terms of a Lamb wave arrival followed by ducted acoustic and/or gravity waves. This pattern of arrivals is not the same at all ranges nor is it independent of the source energy or of the altitude of the source. Earlier, Pierce, using an isothermal, windless atmospheric model, theoretically formulated the distances beyond which the Lamb wave would just be discernible and also where it would dominate the arriving signals for a specified explosion source. In this work the authors have evaluated these distances for the cases of both an inviscid and a viscous fluid for the source energies of interest to the CTBT (Comprehensive Test Ban Treaty) R and D work at Los Alamos. Although the inviscid results are analytic, the fully viscous solutions are iterative. For the inviscid solutions, the authors find that the Lamb wave domination distance is proportional to wave frequency at frequencies large with respect to the acoustic waveguide cut-off frequency. Under similar conditions they also find that the computed distances are linearly proportional to the source height. At 1 Hz for example, the Lamb wave must propagate about 200 km before having a significant amplitude. For a viscous fluid they found slight increases in the distances compared to an inviscid fluid with the lower frequencies, near the acoustic cut-off frequency, exhibiting the greatest changes. During the period from 1981--1994 at Los Alamos, they have also observed infrasound from eight point source, near-surface ANFO explosions at White Sands Missile Range events even though the ducted acoustic waves were observed. In this work, they will compare the current theory against some of these observations.

  7. Fast Lamb wave energy shift approach using fully contactless ultrasonic system to characterize concrete structures

    NASA Astrophysics Data System (ADS)

    Ham, Suyun; Popovics, John S.

    2015-03-01

    Ultrasonic techniques provide an effective non-destructive evaluation (NDE) method to monitor concrete structures, but the need to perform rapid and accurate structural assessment requires evaluation of hundreds, or even thousands, of measurement datasets. Use of a fully contactless ultrasonic system can save time and labor through rapid implementation, and can enable automated and controlled data acquisition, for example through robotic scanning. Here we present results using a fully contactless ultrasonic system. This paper describes our efforts to develop a contactless ultrasonic guided wave NDE approach to detect and characterize delamination defects in concrete structures. The developed contactless sensors, controlled scanning system, and employed Multi-channel Analysis of Surface Waves (MASW) signal processing scheme are reviewed. Then a guided wave interpretation approach for MASW data is described. The presence of delamination is interpreted by guided plate wave (Lamb wave) behavior, where a shift in excited Lamb mode phase velocity, is monitored. Numerically simulated and experimental ultrasonic data collected from a concrete sample with simulated delamination defects are presented, where the occurrence of delamination is shown to be associated with a mode shift in Lamb wave energy.

  8. Combined analytical FEM approach for efficient simulation of Lamb wave damage detection.

    PubMed

    Shen, Yanfeng; Giurgiutiu, Victor

    2016-07-01

    Lamb waves have been widely explored as a promising inspection tool for non-destructive evaluation (NDE) and structural health monitoring (SHM). This article presents a combined analytical finite element model (FEM) approach (CAFA) for the accurate, efficient, and versatile simulation of 2-D Lamb wave propagation and interaction with damage. CAFA used a global analytical solution to model wave generation, propagation, scattering, mode conversion, and detection, while the wave-damage interaction coefficients (WDICs) were extracted from harmonic analysis of local FEM with non-reflective boundaries (NRB). The analytical procedure was coded using MATLAB, and a predictive simulation tool called WaveFormRevealer 2-D was developed. The methodology of obtaining WDICs from local FEM was presented. Case studies were carried out for Lamb wave propagation in a pristine plate and a damaged plate. CAFA predictions compared well with full scale multi-physics FEM simulations and experiments with scanning laser Doppler vibrometry (SLDV), while achieving remarkable performance in computational efficiency and computer resource saving compared with conventional FEM. PMID:27085109

  9. Numerical and experimental study of Lamb wave propagation in a two-dimensional acoustic black hole

    NASA Astrophysics Data System (ADS)

    Yan, Shiling; Lomonosov, Alexey M.; Shen, Zhonghua

    2016-06-01

    The propagation of laser-generated Lamb waves in a two-dimensional acoustic black-hole structure was studied numerically and experimentally. The geometrical acoustic theory has been applied to calculate the beam trajectories in the region of the acoustic black hole. The finite element method was also used to study the time evolution of propagating waves. An optical system based on the laser-Doppler vibration method was assembled. The effect of the focusing wave and the reduction in wave speed of the acoustic black hole has been validated.

  10. Impact damage detection in sandwich composite structures using Lamb waves and laser vibrometry

    NASA Astrophysics Data System (ADS)

    Lamboul, B.; Passilly, B.; Roche, J.-M.; Osmont, D.

    2013-01-01

    This experimental study explores the feasibility of impact damage detection in composite sandwich structures using Lamb wave excitation and signals acquired with a laser Doppler vibrometer. Energy maps are computed from the transient velocity wave fields and used to highlight defect areas in impacted coupons of foam core and honeycomb core sandwich materials. The technique performs well for the detection of barely visible damage in this type of material, and is shown to be robust in the presence of wave reverberation. Defect extent information is not always readily retrieved from the obtained defect signatures, which depend on the wave - defect interaction mechanisms.

  11. Novel Piezoelectric Fiber Transducers for Mode Selective Excitation and Detection of Lamb Waves

    NASA Astrophysics Data System (ADS)

    Koehler, B.; Frankenstein, B.; Schubert, F.; Barth, M.

    2009-03-01

    One of the most widely applied methods for Structural Health Monitoring of plate like structures, shells and tubes is based on the transmission and reception of guided elastic waves. But, dispersion of various wave modes leads to complex signals which are difficult to interpret. Piezoelectric fiber patches (PFP) have been developed which can be used to excite and detect Lamb waves. These are of low thickness having the potential to be integrated into structures. This paper deals with a novel method to excite PFP. By this method a Lamb modes can be both excited and detected selectively. In addition, also directivity can be realized. These sensors can be used to simplify the interpretation of the acoustic signals considerably.

  12. Temperature effects on the band gaps of Lamb waves in a one-dimensional phononic-crystal plate (L).

    PubMed

    Cheng, Y; Liu, X J; Wu, D J

    2011-03-01

    This study investigates the temperature-tuned band gaps of Lamb waves in a one-dimensional phononic-crystal plate, which is formed by alternating strips of ferroelectric ceramic Ba(0.7)Sr(0.3)TiO(3) and epoxy. The sensitive and continuous temperature-tunability of Lamb wave band gaps is demonstrated using the analyses of the band structures and the transmission spectra. The width and position of Lamb wave band gaps shift prominently with variation of temperature in the range of 26 °C-50 °C. For example, the width of the second band gap increases from 0.066 to 0.111 MHz as the temperature is increased from 26 °C to 50 °C. The strong shift promises that the structure could be suitable for temperature-tuned multi-frequency Lamb wave filters. PMID:21428478

  13. Lamb wave characterization of the effects of long-term thermal-mechanical aging on composite stiffness

    NASA Technical Reports Server (NTRS)

    Seale, M. D.; Madaras, E. I.

    1999-01-01

    Lamb waves offer a promising method of evaluating damage in composite materials. The Lamb wave velocity is directly related to the material parameters, so an effective tool exists to monitor damage in composites by measuring the velocity of these waves. The Lamb Wave Imager (LWI) uses a pulse/receive technique that excites an antisymmetric Lamb mode and measures the time-of-flight over a wide frequency range. Given the material density and plate thickness, the bending and out-of-plane shear stiffnesses are calculated from a reconstruction of the dispersion curve. In this study, the time-of-flight as well as the elastic stiffnesses D11, D22, A44, and A55 for composite samples which have undergone combined thermal and mechanical aging are obtained. The samples examined include a baseline specimen with 0 cycles, specimens which have been aged 2350 and 3530 cycles at high strain levels, and one specimen aged 3530 cycles at low strain levels.

  14. Damage Evaluation of Unsaturated Polyester Resin Using Zero-Group Velocity Lamb Waves in Non-Contact Matter

    NASA Astrophysics Data System (ADS)

    Cho, Hideo; Oka, Daichi; Matsuo, Takuma

    In this study we attempted to evaluate the degree of degradation of an unsaturated polyester resin when it was degraded by exposing it to hot water at 90°C, using the frequency of zero-group-velocity (ZGV) Lamb waves. The energy of ZGV Lamb waves does not propagate while the phase velocity remains finite. We generated ZGV Lamb waves with a Q-switched YAG laser and detected them with a focused air-coupled transducer at the same area of an irradiation point of the YAG laser in con-contact matter. A change in measured frequencies of ZGV Lamb waves decreased with increase of exposed period to hot water and are corresponding to the change in Young's modulus and thickness of the plate near the exposed surface

  15. Lamb wave sensing using fiber Bragg grating sensors for delamination detection in composite laminates

    NASA Astrophysics Data System (ADS)

    Takeda, N.; Okabe, Y.; Kuwahara, J.; Kojima, S.

    2005-05-01

    The authors are constructing a damage detection system using ultrasonic waves. In this system, a piezo-ceramic actuator generates Lamb waves in a CFRP laminate. After the waves propagate in the laminate, transmitted waves are received by a fiber Bragg grating (FBG) sensor attached on the laminate using a newly developed high-speed optical wavelength interrogation system. At first, the optimal gauge length of the FBG to detect ultrasonic waves was investigated through theoretical simulations and experiments. Then, the directional sensitivity of the FBG to ultrasonic waves was evaluated experimentally. On the basis of the above results, the 1mm FBG sensors were applied to the detection of Lamb waves propagated in carbon fiber reinforced plastic (CFRP) cross-ply laminates. The piezo-actuator was put on the laminate about 50mm away from the FBG sensor glued on the laminate, and three-cycle sine waves of 300kHz were excited repeatedly. The waveforms obtained by the FBG showed that S0 and A0 modes could be detected appropriately. Then, artificial delamination was made in the laminate by removing of a Teflon sheet embedded in the 0/90 interface after the manufacturing. When the Lamb waves passed through the delamination, the amplitude decreased and a new wave mode appeared. These phenomena could be well simulated using a finite element method. Furthermore, since the amplitude and the velocity of the new mode increased with an increase in the delamination length, this system has a potential to evaluate the interlaminar delamination length quantitatively.

  16. Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Huang, S. L.; Wang, S.; Zhao, W.

    2016-05-01

    The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert-Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

  17. Lamb Wave Dispersion Ultrasound Vibrometry (LDUV) Method for Quantifying Mechanical Properties of Viscoelastic Solids

    PubMed Central

    Nenadic, Ivan Z.; Urban, Matthew W.; Mitchell, Scott A.; Greenleaf, James F.

    2011-01-01

    Diastolic dysfunction is the inability of the left ventricle to supply sufficient stroke volumes under normal physiological conditions and is often accompanied by stiffening of the left-ventricular myocardium. A noninvasive technique capable of quantifying viscoelasticity of the myocardium would be beneficial in clinical settings. Our group has been investigating the use of Shearwave Dispersion Ultrasound Vibrometry (SDUV), a noninvasive ultrasound based method for quantifying viscoelasticity of soft tissues. The primary motive of this study is the design and testing of viscoelastic materials suitable for validation of the Lamb wave Dispersion Ultrasound Vibrometry (LDUV), an SDUV-based technique for measuring viscoelasticity of tissues with plate-like geometry. We report the results of quantifying viscoelasticity of urethane rubber and gelatin samples using LDUV and an embedded sphere method. The LDUV method was used to excite antisymmetric Lamb waves and measure the dispersion in urethane rubber and gelatin plates. An antisymmetric Lamb wave model was fitted to the wave speed dispersion data to estimate elasticity and viscosity of the materials. A finite element model of a viscoelastic plate submerged in water was used to study the appropriateness of the Lamb wave dispersion equations. An embedded sphere method was used as an independent measurement of the viscoelasticity of the urethane rubber and gelatin. The FEM dispersion data were in excellent agreement with the theoretical predictions. Viscoelasticity of the urethane rubber and gelatin obtained using the LDUV and embedded sphere methods agreed within one standard deviation. LDUV studies on excised porcine myocardium sample were performed to investigate the feasibility of the approach in preparation for open-chest in vivo studies. The results suggest that the LDUV technique can be used to quantify mechanical properties of soft tissues with a plate-like geometry. PMID:21403186

  18. A micromachined thermally compensated thin film Lamb wave resonator for frequency control and sensing applications

    NASA Astrophysics Data System (ADS)

    Wingqvist, G.; Arapan, L.; Yantchev, V.; Katardjiev, I.

    2009-03-01

    Micromachined thin film plate acoustic wave resonators (FPARs) utilizing the lowest order symmetric Lamb wave (S0) propagating in highly textured 2 µm thick aluminium nitride (AlN) membranes have been successfully demonstrated (Yantchev and Katardjiev 2007 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 54 87-95). The proposed devices have a SAW-based design and exhibit Q factors of up to 3000 at a frequency around 900 MHz as well as design flexibility with respect to the required motional resistance. However, a notable drawback of the proposed devices is the non-zero temperature coefficient of frequency (TCF) which lies in the range -20 ppm K-1 to -25 ppm K-1. Thus, despite the promising features demonstrated, further device optimization is required. In this work temperature compensation of thin AlN film Lamb wave resonators is studied and experimentally demonstrated. Temperature compensation while retaining at the same time the device electromechanical coupling is experimentally demonstrated. The zero TCF Lamb wave resonators are fabricated onto composite AlN/SiO2 membranes. Q factors of around 1400 have been measured at a frequency of around 755 MHz. Finally, the impact of technological issues on the device performance is discussed in view of improving the device performance.

  19. Waveguiding and frequency selection of Lamb waves in a plate with a periodic stubbed surface

    NASA Astrophysics Data System (ADS)

    Wu, Tzung-Chen; Wu, Tsung-Tsong; Hsu, Jin-Chen

    2009-03-01

    In this paper, we numerically and experimentally study the waveguiding of Lamb modes in a thin plate with a periodic stubbed surface and propose a frequency-selection method based on the found complete band gaps of Lamb waves in the periodic structure. In the numerical simulations, we employ finite-element method to analyze the waveguiding effect of a line defect created in the periodic plate structure; and on the experimental side, we utilize a pulsed laser to generate broadband elastic-wave energy and a laser interferometer to receive the wave signals inside the line-defect waveguide. In the experiment, well-confined acoustic energy in the acoustic band gaps is observed. Furthermore, a polyline sharply bent waveguide is designed and used for the frequency selection of Lamb waves. Measurements show that acoustic energy with frequencies in the band gaps can be separated out and guided by the bent waveguiding route. The characteristics of deaf bands found in the experiment are discussed as well.

  20. A numerically-enhanced machine learning approach to damage diagnosis using a Lamb wave sensing network

    NASA Astrophysics Data System (ADS)

    Sbarufatti, C.; Manson, G.; Worden, K.

    2014-09-01

    This paper describes a methodology for the design of a model-based diagnostic unit. The objective of the work is to define a suitable procedure for the design and verification of diagnostic performance in a simulated environment, trying to maximise the generalisation capability of pattern recognition algorithms when tested with real experimental signals. The system is designed and experimentally verified to solve the fatigue crack damage localisation and assessment problems in a realistic, though rather idealised, Structural Health Monitoring (SHM) framework. The study is applied to a piezoelectric Lamb wave sensor network and is validated experimentally on a simple aluminium skin. The analytically-derived dispersion curves for Lamb wave propagation in aluminium are used in order to determine the wave velocities and thus their arrival time at given sensors. The Local Interaction Simulation Approach (LISA) is used to simulate the entire waveform propagation. Once the agreement between analytical, numerical and experimental data is verified on a baseline undamaged condition, the parametric LISA model has been iteratively run, varying the position and the length of a crack on an aluminium skin panel, generating the virtual experience necessary to train a supervised learning regressor based on Artificial Neural Networks (ANNs). After the algorithm structure has been statistically optimised, the network sensitivity to input variations has been evaluated on simulated signals through a technique inspired by information gap theory. Real Lamb wave signals are then processed into the algorithm, providing feasible real-time indication of damage characteristics.

  1. Scattering of the fundamental anti-symmetric Lamb wave at delaminations in composite laminates.

    PubMed

    Ng, Ching-Tai; Veidt, Martin

    2011-03-01

    An analysis of the scattering characteristics of the fundamental anti-symmetric (A(0)) Lamb wave at a delamination in a quasi-isotropic composite laminate is presented. Analytical solutions for this problem do not exist due to the anisotropic nature and multilayer characteristics of composite laminates. This study uses a three-dimensional finite element (FE) method and experimental measurements to provide physical insight into the scattering phenomena. Good agreement is found between simulations and experimental measurements. The results show that the A(0) Lamb wave scattering at a delamination in composite laminates is much more complicated than the scattering at a defect in isotropic plates. Scatter amplitudes and scatter directivity distributions depend on the delamination size to wavelength ratio and the through-thickness location of the delamination damage. The study also investigates the feasibility of the common experimental practice of simulating delamination damage by bonding masses to the surface of composite laminates for guided wave damage detection and characterization methodologies verifications. The results suggest that care is required to use bonded masses to simulate delamination damage for verifying and optimizing damage characterization techniques. In summary, the results of the investigation help to further advance the use of the A(0) Lamb wave for damage detection and characterization. PMID:21428492

  2. Acoustoelasticity

    NASA Technical Reports Server (NTRS)

    Dowell, E. H.

    1976-01-01

    Internal sound fields are considered. Specifically, the interaction between the (acoustic) sound pressure field and the (elastic) flexible wall of an enclosure is discussed. Such problems frequently arise when the vibrating walls of a transportation vehicle induce a significant internal sound field. Cabin noise in various flight vehicles and the internal sound field in an automobile are representative examples. A mathematical model, simplified solutions, and numerical results and comparisons with representative experimental data are briefly considered. An overall conclusion is that reasonable grounds for optimism exist with respect to available theoretical models and their predictive capability.

  3. Performance optimization of high-order Lamb wave sensors based on silicon carbide substrates.

    PubMed

    Chen, Zhe; Fan, Li; Zhang, Shu-yi; Zhang, Hui

    2016-02-01

    Silicon carbide (SiC), as a new type of material for substrates in micro-electromechanical system (MEMS), was given high consideration in virtue of the properties of high acoustic velocity, low loss, chemical resistance, and etc. In this work, five performance parameters, which are electromechanical coupling coefficients, mass sensitivities, conductivity sensitivities, insert losses and minimum detectable masses, are theoretically investigated in Lamb wave chemical sensors for gas sensing based on SiC substrates. It is presented that higher performance can be achieved based on high-order modes other than fundamental modes, and the abovementioned five parameters can be simultaneously optimized. Then, according to the optimized operating conditions, operating parameters of the SiC-based high-order Lamb wave sensors are designed, which can be easily realized in MEMS technology. Finally, it is demonstrates that the SiC-based sensor exhibits better performance than that of the sensor with a conventional silicon substrate. PMID:26474949

  4. Surface-bonded optical fibre sensors for the inspection of CFRP plates using ultrasonic Lamb waves

    NASA Astrophysics Data System (ADS)

    Pierce, S. G.; Philp, W. R.; Culshaw, B.; Gachagan, A.; McNab, A.; Hayward, G.; Lecuyer, F.

    1996-12-01

    Surface-bonded single-mode optical fibre sensors have been used to monitor the interaction of ultrasonic 0964-1726/5/6/007/img9 Lamb waves with defects in carbon fibre composite plates. Lamb waves were initiated using Perspex-coupled piezoelectric transducers. The defects investigated comprised holes, regions of impact damage and delaminations. Holes could be identified by analysing direct 0964-1726/5/6/007/img9 reflections and impact damage by 0964-1726/5/6/007/img9 back-wall echo amplitude. Large delaminations gave a poor direct 0964-1726/5/6/007/img9 reflection. Evidence was found for mode conversion at centre plane delaminations.

  5. Rectification of Lamb wave propagation in thin plates with piezo-dielectric periodic structures

    NASA Astrophysics Data System (ADS)

    Iwasaki, Yuhei; Tsuruta, Kenji; Ishikawa, Atsushi

    2016-07-01

    Based on a heterostructured plate consisting of piezoelectric-ceramic/epoxy-resin composites with different periodicities, we design a novel acoustic diode for the symmetrical/asymmetrical (S/A) mode of Lamb wave at audible ranges. The acoustic diode is constructed with two parts, i.e., the mode conversion part and the mode selection part, and the mode conversion mechanism at the interface is applied to the mode hybridization from S to S+A and for the mode conversion from A to S. The phonon band structures for each part are calculated and optimized so that the mode selection is realized for a specific mode at the junction. Finite-element simulations prove that the proposed acoustic diode achieves efficient rectification at audio frequency ranges for both S and A mode incidences of the Lamb wave.

  6. The effects of air gap reflections during air-coupled leaky Lamb wave inspection of thin plates.

    PubMed

    Fan, Zichuan; Jiang, Wentao; Cai, Maolin; Wright, William M D

    2016-02-01

    Air-coupled ultrasonic inspection using leaky Lamb waves offers attractive possibilities for non-contact testing of plate materials and structures. A common method uses an air-coupled pitch-catch configuration, which comprises a transmitter and a receiver positioned at oblique angles to a thin plate. It is well known that the angle of incidence of the ultrasonic bulk wave in the air can be used to preferentially generate specific Lamb wave modes in the plate in a non-contact manner, depending on the plate dimensions and material properties. Multiple reflections of the ultrasonic waves in the air gap between the transmitter and the plate can produce additional delayed waves entering the plate at angles of incidence that are different to those of the original bulk wave source. Similarly, multiple reflections of the leaky Lamb waves in the air gap between the plate and an inclined receiver may then have different angles of incidence and propagation delays when arriving at the receiver and hence the signal analysis may become complex, potentially leading to confusion in the identification of the wave modes. To obtain a better understanding of the generation, propagation and detection of leaky Lamb waves and the effects of reflected waves within the air gaps, a multiphysics model using finite element methods was established. This model facilitated the visualisation of the propagation of the reflected waves between the transducers and the plate, the subsequent generation of additional Lamb wave signals within the plate itself, their leakage into the adjacent air, and the reflections of the leaky waves in the air gap between the plate and receiver. Multiple simulations were performed to evaluate the propagation and reflection of signals produced at different transducer incidence angles. Experimental measurements in air were in good agreement with simulation, which verified that the multiphysics model can provide a convenient and accurate way to interpret the signals in

  7. Monitoring of fatigue crack growth at fastener holes using guided Lamb waves

    NASA Astrophysics Data System (ADS)

    Fromme, P.; Sayir, M. B.

    2002-05-01

    An experimental method for the detection of fatigue cracks at holes in aluminum specimens is investigated. The first anti-symmetric Lamb wave mode A0 is excited. Using a heterodyne laser interferometer, the scattered field close to the hole during crack growth is monitored. The fatigue crack is initiated and propagated by cyclic tensile loading of the test specimen in a servo-hydraulic testing machine. The measurements are compared to finite difference calculations. Good qualitative agreement is found.

  8. Data fusion for compensation of temperature variations in Lamb-wave based SHM systems

    NASA Astrophysics Data System (ADS)

    Dworakowski, Ziemowit; Ambrozinski, Lukasz; Stepinski, Tadeusz

    2015-03-01

    Temperature variations affect Lamb wave propagation and therefore in this way they can severely limit application of baseline signals in SHM systems. Various techniques are proposed in the paper to solve this problem. New method based on an interpretation of multiple signals acquired in distinct points of the structure is introduced and compared with other widely used approaches. Data fusion is used to merge a number of methods into one with a substantially increased efficiency.

  9. Investigation of Lamb Waves Propagation by Fibre-Coupling Optical Beam Deflection Detection Technique and Finite Element Method

    NASA Astrophysics Data System (ADS)

    Chen, Xiao; Xu, Bo-qiang; Xu, Rong-qing; Shen, Zhong-hua; Lu, Jian; Ni, Xiao-wu

    2004-02-01

    Measurement of laser-generated transient Lamb waves propagation has been performed in 0.25 mm-thick iron plate by using a fibre sensor based on optical beam deflection technique. The detection principle of this optical method is discussed in detail. A high-powered Q-switched Nd:YAG laser was used to excite Lamb waves on the polished surface of iron plate. The well-defined Lamb waveforms, as well as their properties of oscillation and dispersion are presented in this paper. Furthermore, according to the ablation model, the development and propagation of Lamb waves are numerical simulated by the finite element method that has been widely used in laser ultrasonic field. The experimental results show good agreement with the numerical simulation. Therefore, this optical detection technique has considerable potential in ultrasonic field.

  10. Broadband Lamb Wave Trapping in Cellular Metamaterial Plates with Multiple Local Resonances

    PubMed Central

    Zhao, De-Gang; Li, Yong; Zhu, Xue-Feng

    2015-01-01

    We have investigated the Lamb wave propagation in cellular metamaterial plates constructed by bending-dominated and stretch-dominated unit-cells with the stiffness differed by orders of magnitude at an ultralow density. The simulation results show that ultralight metamaterial plates with textured stubs deposited on the surface can support strong local resonances for both symmetric and anti-symmetric modes at low frequencies, where Lamb waves at the resonance frequencies are highly localized in the vibrating stubs. The resonance frequency is very sensitive to the geometry of textured stubs. By reasonable design of the geometry of resonant elements, we establish a simple loaded-bar model with the array of oscillators having a gradient relative density (or weight) that can support multiple local resonances, which permits the feasibility of a broadband Lamb wave trapping. Our study could be potentially significant in designing ingenious weight-efficient acoustic devices for practical applications, such as shock absorption, cushioning, and vibrations traffic, etc. PMID:25790858

  11. Investigations of droplet movement excited by Lamb waves on a non-piezoelectric substrate

    NASA Astrophysics Data System (ADS)

    Liang, Wei; Lindner, Gerhard

    2013-07-01

    A model for the numerical simulation of the movement of liquid droplets excited by Lamb waves propagating on non-piezoelectric substrates was developed, and the results of simulation calculations based on this model were compared with experimental observations. In the experiments antisymmetrical zero order Lamb waves with 1 MHz center frequency were excited on a 1 mm thick glass substrate by piezoelectric single phase transducers, which caused the propulsion of microliter water droplets. The acoustic streaming within the droplet was calculated by solving the incompressible Navier-Stokes equations with an inhomogeneous acoustic streaming force field. These calculations were validated by optical measurements of the streaming effects in the droplet and by measurements of the displacement amplitudes of the Lamb waves with a laser-Doppler-vibrometer. Another part of the numerical simulations was related to the transient motion of acoustically driven droplets by solving the incompressible Navier-Stokes equations using the moving mesh application mode of the comsol software including a weak formulation for the calculation of the surface tension. The corresponding measurements with a high-speed camera revealed a silkworm-like movement of the droplet resulting from the interaction with acoustic force, surface tension, gravity, and inertial force, which was reproduced by the numerical simulations.

  12. Effects of adhesive, host plate, transducer and excitation parameters on time reversibility of ultrasonic Lamb waves.

    PubMed

    Agrahari, J K; Kapuria, S

    2016-08-01

    To develop an effective baseline-free damage detection strategy using the time-reversal process (TRP) of Lamb waves in thin walled structures, it is essential to develop a good understanding of the parameters that affect the amplitude dispersion and consequently the time reversibility of the Lamb wave signal. In this paper, the effects of adhesive layer between the transducers and the host plate, the tone burst count of the excitation signal, the plate thickness, and the piezoelectric transducer thickness on the time reversibility of Lamb waves in metallic plates are studied using experiments and finite element simulations. The effect of adhesive layer on the forward propagation response and frequency tuning has been also studied. The results show that contrary to the general expectation, the quality of the reconstruction of the input signal after the TRP may increase with the increase in the adhesive layer thickness at certain frequency ranges. Similarly, an increase in the tone burst count resulting in a narrowband signal does not necessarily enhance the time reversibility at all frequencies, contrary to what has been reported earlier. For a given plate thickness, a thinner transducer yields a better reconstruction, but for a given transducer thickness, the similarity of the reconstructed signal may not be always higher for a thicker plate. It is important to study these effects to achieve the best quality of reconstruction in undamaged plates, for effective damage detection. PMID:27176646

  13. A signal processing approach to exploit chirp excitation in Lamb wave defect detection and localization procedures

    NASA Astrophysics Data System (ADS)

    De Marchi, Luca; Perelli, Alessandro; Marzani, Alessandro

    2013-08-01

    A non-linear Lamb wave signal processing strategy aimed at extending the capability of active-passive networks of PZT transducers for defect detection is proposed. In particular, the proposed signal processing allows to use chirp shaped pulses in actuation, instead of classically applied spiky pulses, requiring thus lower input voltages. To such aim, the acquired Lamb waves are processed by means of a two-step procedure: a warped frequency transform (WFT) to compensate for the dispersion due to the traveled distance, followed by a compression procedure to remove from the signals the induced chirp frequency modulation. Next, the resulting signals are exploited to feed an imaging algorithm aimed at providing the position of the defect on the plate. The potential of the procedure is demonstrated and validated by analyzing experimental Lamb waves propagating in an aluminum plate where defects were emulated by posing an added mass on the plate. The proposed automatic procedure is suitable to locate defect-induced reflections and can be easily implemented in real applications for structural health monitoring.

  14. PVDF array sensor for Lamb wave reception: Aircraft structural health monitoring

    NASA Astrophysics Data System (ADS)

    Ren, Baiyang; Lissenden, Cliff J.

    2016-02-01

    Fracture critical structures need structural health monitoring (SHM) to improve safety and reliability as well as reduce downtime and maintenance costs. Lamb waves provide promising techniques for on-line SHM systems because of their large volumetric coverage and good sensitivity to defects. Extensive research has focused on using features derived from time signals obtained at sparse locations distributed across the structure. Commonly used features are wave amplitude, energy, and time of arrival. However, the modal content of received Lamb waves contains valuable information about the existence and characteristics of defects, but cannot be determined from these signal features. Wave scattering at a defect often results in mode conversions in both transmitted and reflected waves. Features like change in time of arrival or amplitude reduction can be interpreted as being a result of mode conversion. This work is focused on the design of a 1D array sensor such that received wave signals at equally spaced locations are available for modal analysis in the wavenumber-frequency domain. PVDF (polyvinylidene fluoride) is selected as the active material of the sensor because of its low interference with wave fields in structures. The PVDF array sensor is fabricated to have 16 independent channels and its capability to detect and characterize different types of defects is demonstrated experimentally.

  15. Wall thickness measurement using resonant phenomena of circumferential Lamb waves generated by plural transducer elements located evenly on girth

    NASA Astrophysics Data System (ADS)

    Nishino, Hideo; Iwata, Kodai; Ishikawa, Masashi

    2016-07-01

    We present a novel method of measuring the pipe wall thickness using the resonance of the circumferential (C-) Lamb wave generated by a piezoelectric ring-shaped sensor (PS). The PS is a special device for an axially propagating torsional wave; however, the C-Lamb waves are generated simultaneously as spurious signals owing to the structure of the PS. Particularly under resonant conditions, the C-Lamb waves are dominantly generated, distorting the axially propagating wave. In this method, these troublesome spurious signals are used effectively for the measurement of the wall thickness under the PS location that is a dead zone of the PS itself. The method can compensate for its drawback, namely, the dead zone problem, without using additional instruments. In this study, the mechanisms of the generation and resonance of the C-Lamb waves were first explained. Secondly, the principle of the wall thickness estimation utilizing the resonance of the C-Lamb waves was proposed. Finally, experimental verifications were carried out. The estimated wall thicknesses agreed very well (maximum 1.5% error) with those measured by a micrometer caliper under suitable resonant conditions.

  16. Lamb wave excitation and propagation in elastic plates with surface obstacles: proper choice of central frequencies

    NASA Astrophysics Data System (ADS)

    Glushkov, Evgeny; Glushkova, Natalia; Lammering, Rolf; Eremin, Artem; Neumann, Mirko N.

    2011-01-01

    Experimental and theoretical investigations of Lamb wave excitation and sensing using piezo patch transducers and the laser vibrometer technique have been performed, aiming at the development of adequate mathematical and computer models for the interpretation of sensing data and for the choice of optimal parameters for structural health monitoring. The proposed models are validated by experimental results. Furthermore, a methodology is presented which allows for the determination of central frequencies at which maximal values of the structural response spectrum can be expected in the case of wave propagation monitoring with laser vibrometry.

  17. Fatigue crack detection in metallic structures with Lamb waves and 3D laser vibrometry

    NASA Astrophysics Data System (ADS)

    Staszewski, W. J.; Lee, B. C.; Traynor, R.

    2007-03-01

    The paper presents the application of ultrasonic guided waves for fatigue crack detection in metallic structures. The study involves a simple fatigue test performed to introduce a crack into an aluminium plate. Lamb waves generated by a low-profile, surface-bonded piezoceramic transducer are sensed using a tri-axis, multi-position scanning laser vibrometer. The results demonstrate the potential of laser vibrometry for simple, rapid and robust detection of fatigue cracks in metallic structures. The method could be used in quality inspection and in-service maintenance of metallic structures in aerospace, civil and mechanical engineering industries.

  18. Extremely low-frequency Lamb wave band gaps in a sandwich phononic crystal thin plate

    NASA Astrophysics Data System (ADS)

    Shen, Li; Wu, Jiu Hui; Liu, Zhangyi; Fu, Gang

    2015-11-01

    In this paper, a kind of sandwich phononic crystal (PC) plate with silicon rubber scatterers embedded in polymethyl methacrylate (PMMA) matrix is proposed to demonstrate its low-frequency Lamb wave band gap (BG) characteristics. The dispersion relationship and the displacement vector fields of the basic slab modes and the locally resonant modes are investigated to show the BG formation mechanism. The anti-symmetric Lamb wave BG is further studied due to its important function in reducing vibration. The analysis on the BG characteristics of the PC through changing their geometrical parameters is performed. By optimizing the structure, a sandwich PC plate with a thickness of only 3 mm and a lower boundary (as low as 23.9 Hz) of the first anti-symmetric BG is designed. Finally, sound insulation experiment on a sandwich PC plate with the thickness of only 2.5 mm is conducted, showing satisfactory noise reduction effect in the frequency range of the anti-symmetric Lamb BG. Therefore, this kind of sandwich PC plate has potential applications in controlling vibration and noise in low-frequency ranges.

  19. Lamb wave detection of limpet mines on ship hulls.

    PubMed

    Bingham, Jill; Hinders, Mark; Friedman, Adam

    2009-12-01

    This paper describes the use of ultrasonic guided waves for identifying the mass loading due to underwater limpet mines on ship hulls. The Dynamic Wavelet Fingerprint Technique (DFWT) is used to render the guided wave mode information in two-dimensional binary images because the waveform features of interest are too subtle to identify in time domain. The use of wavelets allows both time and scale features from the original signals to be retained, and image processing can be used to automatically extract features that correspond to the arrival times of the guided wave modes. For further understanding of how the guided wave modes propagate through the real structures, a parallel processing, 3D elastic wave simulation is developed using the finite integration technique (EFIT). This full field, technique models situations that are too complex for analytical solutions, such as built up 3D structures. The simulations have produced informative visualizations of the guided wave modes in the structures as well as mimicking directly the output from sensors placed in the simulation space for direct comparison to experiments. Results from both drydock and in-water experiments with dummy mines are also shown. PMID:19541335

  20. Acousto-optic modulation of a photonic crystal nanocavity with Lamb waves in microwave K band

    SciTech Connect

    Tadesse, Semere A.; Li, Huan; Liu, Qiyu; Li, Mo

    2015-11-16

    Integrating nanoscale electromechanical transducers and nanophotonic devices potentially can enable acousto-optic devices to reach unprecedented high frequencies and modulation efficiency. Here, we demonstrate acousto-optic modulation of a photonic crystal nanocavity using Lamb waves with frequency up to 19 GHz, reaching the microwave K band. The devices are fabricated in suspended aluminum nitride membrane. Excitation of acoustic waves is achieved with interdigital transducers with period as small as 300 nm. Confining both acoustic wave and optical wave within the thickness of the membrane leads to improved acousto-optic modulation efficiency in these devices than that obtained in previous surface acoustic wave devices. Our system demonstrates a scalable optomechanical platform where strong acousto-optic coupling between cavity-confined photons and high frequency traveling phonons can be explored.

  1. Time-frequency beamforming for nondestructive evaluations of plate using ultrasonic Lamb wave

    NASA Astrophysics Data System (ADS)

    Han, Je-Heon; Kim, Yong-Joe

    2015-03-01

    The objective of this study is to detect structural defect locations in a plate by exciting the plate with a specific ultrasonic Lamb wave and recording reflective wave signals using a piezoelectric transducer array. For the purpose of eliminating the effects of the direct excitation signals as well as the boundary-reflected wave signals, it is proposed to improve a conventional MUSIC beamforming procedure by processing the measured signals in the time-frequency domain. In addition, a normalized, damped, cylindrical 2-D steering vector is proposed to increase the spatial resolution of time-frequency MUSIC power results. A cross-shaped array is selected to further improve the spatial resolution and to avoid mirrored virtual image effects. Here, it is experimentally demonstrated that the proposed time-frequency MUSIC beamforming procedure can be used to identify structural defect locations on an aluminum plate by distinguishing the defect-induced waves from the excitation-generated and boundary-reflected waves.

  2. Non-contact feature detection using ultrasonic Lamb waves

    DOEpatents

    Sinha, Dipen N.

    2011-06-28

    Apparatus and method for non-contact ultrasonic detection of features on or within the walls of hollow pipes are described. An air-coupled, high-power ultrasonic transducer for generating guided waves in the pipe wall, and a high-sensitivity, air-coupled transducer for detecting these waves, are disposed at a distance apart and at chosen angle with respect to the surface of the pipe, either inside of or outside of the pipe. Measurements may be made in reflection or transmission modes depending on the relative position of the transducers and the pipe. Data are taken by sweeping the frequency of the incident ultrasonic waves, using a tracking narrow-band filter to reduce detected noise, and transforming the frequency domain data into the time domain using fast Fourier transformation, if required.

  3. A Defect Localization Procedure Based on Warped Lamb Waves

    NASA Astrophysics Data System (ADS)

    De Marchi, L.; Marzani, A.; Caporale, S.; Speciale, N.

    Passive defect location procedures based on ultrasonic guided waves are widely used for structural health monitoring purposes of plate-like structures. Approaches based on the measured time-of-flight delay of propagating waves recorded at different locations are generally adopted. In these approaches, uncertainties are due to the fixed speed assumed for the incoming waves to convert their time delay in distances. These distances are next used to solve a triangulation scheme that leads to the defect location. In this paper, this inconvenient is avoided by processing the time transient measurements acquired at the different locations with a "Warped Frequency Transform" (WFT) that is capable to reveal the distance travelled by dispersive waves. In fact, by means of the WFT the recorded time waveform is converted into the incipient pulse at a distance from the origin which is proportional to the distance travelled by a mode within the signal, thus fully compensating its dispersive effect. Then, the processed time waveforms recorded from simple sensors can be used for locating defects by means of classical triangulation procedures.

  4. Rayleigh-Lamb Waves in Transversely Isotropic Thermoelastic Diffusive Layer

    NASA Astrophysics Data System (ADS)

    Kumar, Rajneesh; Kansal, Tarun

    2009-04-01

    Propagation of plane harmonic thermoelastic diffusive waves in a homogeneous, transversely isotropic, thin elastic layer of finite width is studied, in the context of the theory of coupled thermoelastic diffusion. According to the characteristic equation, three quasi-longitudinal waves, namely, quasi-elastodiffusive (QED) mode, quasi-mass diffusion (QMD) mode, and quasi-thermodiffusive (QTD) mode can propagate in addition to quasi-transverse waves (QSV) mode and the purely quasi-transverse motion (QSH) mode, which is not affected by thermal and diffusion vibrations, gets decoupled from the rest of the motion of wave propagation. The secular equations corresponding to the symmetric and skew symmetric modes of the layer are derived. The amplitudes of displacements, temperature change, and concentration for symmetric and skew symmetric modes of vibration of the layer are computed numerically. Anisotropy and diffusion effects on the phase velocity, attenuation coefficient, and amplitudes of displacements, temperature change, and concentration are presented graphically in order to illustrate and compare the results analytically. Some special cases of the frequency equation are also deduced and compared with the existing results.

  5. Phase velocities and attenuations of shear, Lamb, and Rayleigh waves in plate-like tissues submerged in a fluid (L).

    PubMed

    Nenadic, Ivan Z; Urban, Matthew W; Bernal, Miguel; Greenleaf, James F

    2011-12-01

    In the past several decades, the fields of ultrasound and magnetic resonance elastography have shown promising results in noninvasive estimates of mechanical properties of soft tissues. These techniques often rely on measuring shear wave velocity due to an external or internal source of force and relating the velocity to viscoelasticity of the tissue. The mathematical relationship between the measured velocity and material properties of the myocardial wall, arteries, and other organs with non-negligible boundary conditions is often complicated and computationally expensive. A simple relationship between the Lamb-Rayleigh dispersion and the shear wave dispersion is derived for both the velocity and attenuation. The relationship shows that the shear wave velocity is around 20% higher than the Lamb-Rayleigh velocity and that the shear wave attenuation is about 20% lower than the Lamb-Rayleigh attenuation. Results of numerical simulations in the frequency range 0-500 Hz are presented. PMID:22225009

  6. Visualization studies of Lamb wave propagation and interactions with anomalies in composite laminates using air-coupled ultrasonics

    NASA Astrophysics Data System (ADS)

    Sasanka Durvasula, V. S.; Madhavan, Vivek; Padiyar M, Janardhan; Giridharan, N. V.; Balasubramaniam, Krishnan

    2014-02-01

    An experimental method to visualize the propagation of ultrasonic Lamb waves in composite plates with delaminations, using air coupled ultrasonic transducers, is described here. Using this method experiments are done, on glass fiber reinforced plastic(GFRP) laminates, to study the Lamb wave interactions with delamination type defects. The S0 and A0 modes are chosen for experiments at an excitation frequency of 200 kHz. Defect dimensions are calculated from the visualization images and compared with actual values. A method for detecting depth of defects using deviation of wave-fronts, at the defect contours, is presented.

  7. Evaluation of layer thickness in human teeth using higher-order-mode leaky Lamb wave interdigital transducers

    SciTech Connect

    Toda, Shinji; Fujita, Takeshi; Arakawa, Hirohisa; Toda, Kohji

    2005-03-01

    An ultrasonic nondestructive evaluation technique of the layer thickness in human teeth is proposed using a leaky Lamb wave device with two arch-shaped interdigital transducers, operating at a plate/water interface. The use of a higher-order-mode leaky Lamb wave with a phase velocity higher than the longitudinal wave velocity in the human tooth is essential to detect reflected ultrasound beams from the tooth section The layer thickness of dentin, estimated from the measured time interval between two reflected echoes, is in good agreement with the optically measured data.

  8. Lamb waves based fast subwavelength imaging using a DORT-MUSIC algorithm

    NASA Astrophysics Data System (ADS)

    He, Jiaze; Yuan, Fuh-Gwo

    2016-02-01

    A Lamb wave-based, subwavelength imaging algorithm is developed for damage imaging in large-scale, plate-like structures based on a decomposition of the time-reversal operator (DORT) method combined with the multiple signal classification (MUSIC) algorithm in the space-frequency domain. In this study, a rapid, hybrid non-contact scanning system was proposed to image an aluminum plate using a piezoelectric linear array for actuation and a laser Doppler vibrometer (LDV) line-scan for sensing. The physics of wave propagation, reflection, and scattering that underlies the response matrix in the DORT method is mathematically formulated in the context of guided waves. The singular value decomposition (SVD) and MUSIC-based imaging condition enable quantifying the damage severity by a `reflectivity' parameter and super-resolution imaging. With the flexibility of this scanning system, a considerably large area can be imaged using lower frequency Lamb waves with limited line-scans. The experimental results showed that the hardware system with a signal processing tool such as the DORT-MUSIC (TR-MUSIC) imaging technique can provide rapid, highly accurate imaging results as well as damage quantification with unknown material properties.

  9. EMAT-generated Lamb waves for volumetric inspection of strip steel

    NASA Astrophysics Data System (ADS)

    Latham, Wayne M.; Latimer, P. J.; MacLauchlan, Daniel T.; Camplin, Kenneth R.; Lang, Dennis D.

    1998-03-01

    The detection of longitudinally oriented defects in steel plate using ultrasonics has been widely reported. Ultrasonic methods are capable of detecting extremely small volume flaws in strip steel, but are limited because of the need to maintain fluid couplant between the transducer and steel strip. At a minimum, this couplant requirement slows the test speeds considerably, can introduce errors in test results, and, in many cases, prevents the test from being performed at all. The purpose of this paper is to present the results of the investigation of EMAT generated Lamb waves for the volumetric inspection of steel strip and subsequent on-line system performance. The strip steel industry has described a manufacturing problem of internal inclusions in their strip steel product for use in the automotive/appliance industry which is manifested after the rolling operation. The 'pencil pipe', a non-metallic inclusion introduced during the continuous casting process, is not detected prior to the roll, and after rolling it is too late to recover. A major midwestern US steel company considers this defect to be their number one quality problem. A method of detecting these inclusions prior to rolling was needed and is the basis of this development. The objective of this evaluation was the selection and implementation of EMAT generated Lamb wave modes that could be used for on-line detection of pencil pipe defects in strip steel before the strip is rolled to its final thickness. In addition, different Lamb waves modes were used to discriminate between the internal pencil pipe and non- deleterious surface scratches.

  10. A Lamb waves based statistical approach to structural health monitoring of carbon fibre reinforced polymer composites.

    PubMed

    Carboni, Michele; Gianneo, Andrea; Giglio, Marco

    2015-07-01

    This research investigates a Lamb-wave based structural health monitoring approach matching an out-of-phase actuation of a pair of piezoceramic transducers at low frequency. The target is a typical quasi-isotropic carbon fibre reinforced polymer aeronautical laminate subjected to artificial, via Teflon patches, and natural, via suitable low velocity drop weight impact tests, delaminations. The performance and main influencing factors of such an approach are studied through a Design of Experiment statistical method, considering both Pulse Echo and Pitch Catch configurations of PZT sensors. Results show that some factors and their interactions can effectively influence the detection of a delamination-like damage. PMID:25746761

  11. Interdigital transducers in structural health monitoring based on Lamb waves: a state of the art

    NASA Astrophysics Data System (ADS)

    Stepinski, Tadeusz; Mańka, Michał; Martowicz, Adam; Rathod, Vivek T.

    2016-04-01

    IDTs have the potential of increasing the versatility of SHM systems by their multiple capabilities. Migration of the IDT technology in SHM systems and devices is reviewed in this paper. A summary review of different types of IDTs is presented and their salient features are presented in terms of applicability in the Lamb wave based SHM systems. Comprehensive review is provided concerning the implementation of IDT capabilities towards the development of SHM systems. Experimental results obtained with prototype IDTs are provided for illustration. Finally, future development directions of the IDTs dedicated to SHM systems are outlined.

  12. PZT-induced Lamb waves and pattern recognitions for on-line health monitoring of jointed steel plates

    NASA Astrophysics Data System (ADS)

    Park, Seung-Hee; Yun, Chung-Bang; Roh, Yongrae

    2005-05-01

    This paper presents a non-destructive evaluation (NDE) technique for detecting damages on a jointed steel plate on the basis of the time of flight and wavelet coefficient, obtained from wavelet transforms of Lamb wave signals. Probabilistic neural networks (PNNs) and support vector machines (SVMs), which are tools for pattern classification problems, were applied to the damage estimation. Two kinds of damages were artificially introduced by loosening bolts located in the path of the Lamb waves and those out of the path. The damage cases were used for the establishment of the optimal decision boundaries which divide each damage class"s region from the intact class. In this study, the applicability of the PNNs and SVMs was investigated for the damages in and out of the Lamb wave path. It has been found that the present methods are very efficient in detecting the damages simulated by loose bolts on the jointed steel plate.

  13. Characterisation of hidden defects using the near-field ultrasonic enhancement of Lamb waves.

    PubMed

    Clough, A R; Edwards, R S

    2015-05-01

    Defects that propagate from the inside of a structure can be difficult to detect by traditional non-destructive inspection methods. A non-contact inspection method is presented here that uses the near-field interactions of ultrasonic Lamb waves to detect defects propagating into a 1.5 mm thick aluminium sheet from the opposite side to that which is inspected. Near-field interactions of the S0 Lamb waves with the defects are shown to give rise to a characteristic increase in the wave magnitude, which is used to position and characterise these hidden defects. It is shown that such defects are difficult to detect from a study of their influence on ultrasonic transmission alone. Single defects of different depths, and systems of multiple defects with varying separations and relative depths, are successfully detected in both experimental trials and FEM simulations. Reliable single defect detection is achieved for defects with a minimum depth of 30% of the plate thickness, and resolution of multiple defects is achieved for defect separations of 5mm. PMID:25682295

  14. Lamb wave inspection for large cracks in centrifugally cast stainless steel: Interim report

    SciTech Connect

    Not Available

    1988-08-01

    The objective of the present research project is to develop an inspection technique to detect and size large-scale cracks in centrifugally cast stainless steel (CCSS) pipes. This technique is based on the use of Lamb waves, or generally the resonant modes of propagation in the considered geometry, to circumvent the difficulties encountered when the conventional ultrasonic bulk waves are used to inspect the anisotropic, highly absorptive CCSS material. The research activities in 1987 were focused on probe design, Lamb-wave mode selection and excitation, detection mechanism, and anisotropy and curvature effects. The optimal design of a laboratory search unit was determined to be a tandem dual-element system built on the liquid-wedge principle. A reliable mechanism, which features a strong amplitude reduction when the search unit is scanned over a crack, was identified for crack detection and location. The preliminary experimental and analytical findings indicate that the best resonant modes were identified to be the four lowest modes in light of their excitability and minimization of the anisotropy effect. Finally, for typical geometrical dimensions under consideration, the curvature effect was found to be minimal.

  15. Super-resolution experiments on Lamb waves using a single emitter

    NASA Astrophysics Data System (ADS)

    Rupin, Matthieu; Catheline, Stefan; Roux, Philippe

    2015-01-01

    In this letter, we present super-resolution experiments from a single emission channel located in the far-field of an elastic metamaterial for Lamb waves. The experiment is performed in the kHz regime, with centimetric waves that are refocused numerically through cross-correlation computations. The originality of this approach lies in the direct link established between super-resolution results and the wavefield dispersion induced by a metamaterial made of long rods that are attached to a plate, and that behave as sub-wavelength resonators. We believe that such a clear origin of a far-field super-resolution experiment is of major interest for the design of a meta-lens for waves in plates.

  16. Laser-Generated Lamb Waves Propagation in Multilayered Plates Composed of Viscoelastic Fiber-reinforced Composite Materials

    NASA Astrophysics Data System (ADS)

    Sun, Hong-xiang; Zhang, Shu-yi; Yuan, Shou-qi; Guan, Yi-jun; Ge, Yong

    2016-07-01

    The propagation characteristics of laser-generated Lamb waves in multilayered fiber-reinforced composite plates with different fiber orientations and number of layers have been investigated quantitatively. Considering the viscoelasticity of the composite materials, we have set up finite element models for simulating the laser-generated Lamb waves in two types of the multilayered composite plates. In the first type, different fiber orientations are adopted. In the second one, different number of layers are considered. The results illustrate the occurrence of attenuation and dispersion, which is induced by the viscoelasticity and multilayer structure, respectively.

  17. Simulation of Lamb wave propagation for the characterization of complex structures.

    PubMed

    Agostini, Valentina; Delsanto, Pier Paolo; Genesio, Ivan; Olivero, Dimitri

    2003-04-01

    Reliable numerical simulation techniques represent a very valuable tool for analysis. For this purpose we investigated the applicability of the local interaction simulation approach (LISA) to the study of the propagation of Lamb waves in complex structures. The LISA allows very fast and flexible simulations, especially in conjunction with parallel processing, and it is particularly useful for complex (heterogeneous, anisotropic, attenuative, and/or nonlinear) media. We present simulations performed on a glass fiber reinforced plate, initially undamaged and then with a hole passing through its thickness (passing-by hole). In order to give a validation of the method, the results are compared with experimental data. Then we analyze the interaction of Lamb waves with notches, delaminations, and complex structures. In the first case the discontinuity due to a notch generates mode conversion, which may be used to predict the defect shape and size. In the case of a single delamination, the most striking "signature" is a time-shift delay, which may be observed in the temporal evolution of the signal recorded by a receiver. We also present some results obtained on a geometrically complex structure. Due to the inherent discontinuities, a wealth of propagation mechanisms are observed, which can be exploited for the purpose of quantitative nondestructive evaluation (NDE). PMID:12744400

  18. Statistical updating of finite element model with Lamb wave sensing data for damage detection problems

    NASA Astrophysics Data System (ADS)

    Vanli, O. Arda; Jung, Sungmoon

    2014-01-01

    Health monitoring of large structures with embedded, distributed sensor systems is gaining importance. This study proposes a new probabilistic model updating method in order to improve the damage prediction capability of a finite element analysis (FEA) model with experimental observations from a Lamb-wave sensing system. The approach statistically calibrates unknown parameters of the FEA model and estimates a bias-correcting function to achieve a good match between the model predictions and sensor observations. An experimental validation study is presented in which a set of controlled damages are generated on a composite panel. Time-series signals are collected with the damage condition using a Lamb-wave sensing system and a one dimensional FEA model of the panel is constructed to quantify the damages. The damage indices from both the experiments and the computational model are used to calibrate assumed parameters of the FEA model and to estimate a bias-correction function. The updated model is used to predict the size (extent) and location of damage. It is shown that the proposed model updating approach achieves a prediction accuracy that is superior to a purely statistical approach or a deterministic model calibration approach.

  19. Delamination detection in composite laminates using dispersion change based on mode conversion of Lamb waves

    NASA Astrophysics Data System (ADS)

    Okabe, Yoji; Fujibayashi, Keiji; Shimazaki, Mamoru; Soejima, Hideki; Ogisu, Toshimichi

    2010-11-01

    A new ultrasonic propagation system has been constructed using macrofiber composite (MFC) actuators and fiber Bragg grating (FBG) sensors. The MFCs and FBGs can be integrated into composite laminates because of their small size and high fracture strain. The developed system can send and receive broadband Lamb waves. In this research, this system was used to detect delamination damage in composite laminates. First, the multiple modes of Lamb waves in a carbon-fiber-reinforced plastic (CFRP) quasi-isotropic laminate were identified by transmitting and receiving the symmetric and antisymmetric modes separately. Then, the mode conversions at both tips of a delamination were investigated through an experiment and a two-dimensional finite element analysis (FEA). A new delamination detection method was proposed on the basis of the mode conversions, and experiments were carried out on laminates with an artificial delamination. When antisymmetric modes were excited, the frequency dispersion of the received A1 mode changed, depending on the delamination length owing to the mode conversion between the A1 mode and the S0 mode. This phenomenon was confirmed through the FEA and these results prove that this new method is effective in detecting a delamination in CFRP laminates.

  20. Lamb wave based automatic damage detection using matching pursuit and machine learning

    NASA Astrophysics Data System (ADS)

    Agarwal, Sushant; Mitra, Mira

    2014-08-01

    In this study, matching pursuit (MP) has been tested with machine learning algorithms such as artificial neural networks (ANNs) and support vector machines (SVMs) to automate the process of damage detection in metallic plates. Here, damage detection is done using the Lamb wave response in a thin aluminium plate simulated using a finite element (FE) method. To reduce the complexity of the Lamb wave response, only the {{A}_{0}} mode is excited and sensed. The procedure adopted for damage detection consists of three major steps, involving signal processing and machine learning (ML). In the first step, MP is used for de-noising and enhancing the sparsity of the database. In the existing literature, MP is used to decompose any signal into a linear combination of waveforms that are selected from a redundant dictionary. In this work, MP is deployed in two stages to make the database sparse as well as to de-noise it. After using MP on the database, it is then passed as input data for ML classifiers. ANN and SVM are used to detect the location of the potential damage from the reduced data. The study demonstrates that the SVM is a robust classifier in the presence of noise and is more efficient than the ANN. Out-of-sample data are used for the validation of the trained and tested classifier. Trained classifiers are found to be successful in the detection of damage with a detection rate of more than 95%.

  1. Thickness measurements of sub-millimetre thickness foils using Lamb wave dispersion

    NASA Astrophysics Data System (ADS)

    McAughey, K. L.; Edwards, R. S.; Potter, M. D. G.; Dixon, S.

    2015-03-01

    Ultrasonic thickness measurements of sub-millimetre thickness samples are typically performed using either resonance techniques or by using delay lines with contact pulse-echo transducers. The use of a contact transducer with a delay line will change the boundary conditions of the foil, and could negatively impact the reliability of the results, thus a non-contact measurement technique must be used. The use of an electromagnetic acoustic transducer (EMAT) operating at the sample resonance to determine the thickness of the sample still requires a priori knowledge of the material properties, for example the ultrasonic velocities, and any uncertainty in these values due to stress or temperature will lead to an error in the measured thickness. In order to avoid, or at least reduce, the negative effects of uncertainty in the material properties, a technique relying on the dispersion of Lamb waves is used. This technique uses an approximation which relates the velocity of long-wavelength Lamb waves of the anti-symmetric and symmetric fundamental modes (A0 and S0 respectively) to the thickness of the sample. The validity of this approximation has been examined, and thickness measurements have been performed on a number of samples. Additionally, empirical improvements have been considered to extend the range of validity of the approximation, while maintaining the requirement for minimal knowledge of the material properties of the sample.

  2. The use of 0-3 piezocomposite embedded Lamb wave sensors for detection of damage in advanced fibre composites

    NASA Astrophysics Data System (ADS)

    Badcock, R. A.; Birt, E. A.

    2000-06-01

    The use of smart damage-detection systems may have considerable benefits for equipment operators. As sensing elements for a health-monitoring array, piezoelectric elements offer potential benefits. In particular, 0-3 piezocomposite elements have been identified as good candidates since they offer the potential for embedment within the advanced fibre composites. Ultrasonic Lamb waves have been shown to offer a technique for large-area damage detection for composites. It has been shown that the use of the S0 Lamb mode may enable a quantitative estimate of the degree of damage to be obtained. A comparison of various transducer elements for Lamb wave detection is made and the use of embedded 0-3 piezocomposite elements demonstrated.

  3. A novel damage index for fatigue damage detection in a laminated composites using Lamb waves

    NASA Astrophysics Data System (ADS)

    Seki, Daigo

    A well-established structural health monitoring (SHM) technique, the Lamb wave based approach, is used for fatigue damage identification in a laminated composite. A novel damage index, 'normalized correlation moment' (NCM) which is composed of the nth moment of the cross correlation of the baseline and comparison waves, was used as damage index for monitoring damage in composites and compared with the signal difference coefficient (SDC) which is one of the most commonly used damage indices. Composite specimens were fabricated by the hand layup method by followed by compression. Piezo electric disks mounted on composite specimens were used as actuators and sensors. Three point bending fatigue tests were carried out on an intact composite laminate and a delaminated composite laminate with [06/904/06] orientation. Finite element analysis was performed to test the validity of SDC and NCM for fatigue damage.

  4. 2D aperture synthesis for Lamb wave imaging using co-arrays

    NASA Astrophysics Data System (ADS)

    Ambrozinski, Lukasz; Stepinski, Tadeusz; Uhl, Tadeusz

    2014-03-01

    2D ultrasonic arrays in Lamb wave based SHM systems can operate in the phased array (PA) or synthetic focusing (SF) mode. In the real-time PA approach, multiple electronically delayed signals excite transmitting elements to form the desired wave-front, whereas receiving elements are used to sense scattered waves. Due to that, the PA mode requires multi channeled hardware and multiple excitations at numerous azimuths to scan the inspected region of interest. To the contrary, the SF mode, assumes a single element excitation of subsequent transmitters and off-line processing of the acquired data. In the simplest implementation of the SF technique, a single multiplexed input and output channels are required, which results in significant hardware simplification. Performance of a 2D imaging array depends on many parameters, such as, its topology, number of its transducers and their spacing in terms of wavelength as well as the type of weighting function (apodization). Moreover, it is possible to use sparse arrays, which means that not all array elements are used for transmitting and/ or receiving. In this paper the co-array concept is applied to facilitate the synthesis process of an array's aperture used in the multistatic synthetic focusing approach in Lamb waves-based imaging systems. In the coherent imaging, performed in the transmit/receive mode, the sum co-array is a morphological convolution of the transmit/receive sub-arrays. It can be calculated as the set of sums of the individual elements' locations in the sub-arrays used for imaging. The coarray framework will be presented here using two different array topologies, aID uniform linear array and a cross-shaped array that will result in a square coarray. The approach will be discussed in terms of array patterns and beam patterns of the resulting imaging systems. Both, theoretical and experimental results will be given.

  5. Rayleigh to Lamb wave conversion at a delamination-like crack

    NASA Astrophysics Data System (ADS)

    Schaal, Christoph; Samajder, Himadri; Baid, Harsh; Mal, Ajit

    2015-09-01

    Composite structures require careful monitoring to detect and characterize hidden defects at an early stage of their development so that preventive measures can be taken before the structure loses its load carrying capacity and suffers from catastrophic failure. Ultrasonic guided waves offer an attractive tool for inspecting relatively large plate-like structural components due to the waves' large propagation range and sensitivity to defects in their propagation path. Since such waves are affected by geometrical structural features (e.g. stringers) as well as defects (e.g. delaminations), the application of guided waves in real structures requires a good understanding of their interaction with the aforementioned discontinuities. In this paper, a detailed study of the interaction of Rayleigh surface waves with defects in a thick aluminum plate is carried out using numerical simulations and laboratory experiments. The simple aluminum plate is used to demonstrate and analyze the basic characteristics of the interaction phenomena, which are shown to partially result in Lamb wave conversion. Furthermore, the agreement between simulated waveforms and those obtained from experiments are shown, indicating the possibility of applying the techniques to more realistic structures and their use in damage detection systems.

  6. In-Process Detection of Weld Defects Using Laser-Based Ultrasonic Lamb Waves

    SciTech Connect

    Kercel, S W

    2001-01-04

    Laser-based ultrasonic (LBU) measurement shows great promise for on-line monitoring of weld quality in tailor-welded blanks. Tailor-welded blanks are steel blanks made from plates of differing thickness and/or properties butt-welded together; they are used in automobile manufacturing to produce body, frame, and closure panels. LBU uses a pulsed laser to generate the ultrasound and a continuous wave (CW) laser interferometer to detect the ultrasound at the point of interrogation to perform ultrasonic inspection. LBU enables in-process measurements since there is no sensor contact or near-contact with the workpiece. The authors have used laser-generated plate (Lamb) waves to propagate from one plate into the weld nugget as a means of detecting defects. This report recounts an investigation of a number of inspection architectures based on processing of signals from selected plate waves, which are either reflected from or transmitted through the weld zone. Bayesian parameter estimation and wavelet analysis (both continuous and discrete) have shown that the LBU time-series signal is readily separable into components that provide distinguishing features, which describe weld quality. The authors anticipate that, in an on-line industrial application, these measurements can be implemented just downstream from the weld cell. Then the weld quality data can be fed back to control critical weld parameters or alert the operator of a problem requiring maintenance. Internal weld defects and deviations from the desired surface profile can then be corrected before defective parts are produced. The major conclusions of this study are as follows. Bayesian parameter estimation is able to separate entangled Lamb wave modes. Pattern recognition algorithms applied to Lamb mode features have produced robust features for distinguishing between several types of weld defects. In other words, the information is present in the output of the laser ultrasonic hardware, and it is feasible to

  7. Composite Materials NDE Using Enhanced Leaky Lamb Wave Dispersion Data Acquisition Method

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Mal, Ajit; Lih, Shyh-Shiuh; Chang, Zensheu

    1999-01-01

    The leaky Lamb wave (LLW) technique is approaching a maturity level that is making it an attractive quantitative NDE tool for composites and bonded joints. Since it was first observed in 1982, the phenomenon has been studied extensively, particularly in composite materials. The wave is induced by oblique insonification using a pitch-catch arrangement and the plate wave modes are detected by identifying minima in the reflected spectra to obtain the dispersion data. The wave behavior in multi-orientation laminates has been well documented and corroborated experimentally with high accuracy. The sensitivity of the wave to the elastic constants of the material and to the boundary conditions led to the capability to measure the elastic properties of bonded joints. Recently, the authors significantly enhanced the LLW method's capability by increasing the speed of the data acquisition, the number of modes that can be identified and the accuracy of the data inversion. In spite of the theoretical and experimental progress, methods that employ oblique insonification of composites are still not being applied as standard industrial NDE methods. The authors investigated the issues that are hampering the transition of the LLW to industrial applications and identified 4 key issues. The current capability of the method and the nature of these issues are described in this paper.

  8. Investigation of the Higher Harmonic Lamb Wave Generation in Hyperelastic Isotropic Material

    NASA Astrophysics Data System (ADS)

    Rauter, Natalie; Lammering, Rolf

    Micro-structural damages, such as micro-cracks and voids, give locally rise to stresses and may initiate subsequent failure of structural components. Therefore, the development of methods for the detection of microstructural damage and the observation of their growth is an important and ongoing area of research, especially for thin-walled structures. The proposed method for the detection is based on the nonlinearity caused by the micro-structural damages. Lamb waves are generated which induce simultaneously higher harmonic modes due the inherent nonlinearity. For detailed investigations, numerical simulations are essential. In this work, the nonlinearity is modeled by the material law, which is based on the Neo- Hookean and Mooney-Rivlin material models. In contrast to previous studies, which used third order elastic coefficients, these hyperelastic material models are widely accepted, frequently used, and implemented in commonly available FEM software. In the numerical investigations, Lamb waves are generated in a thin-walled aluminum plate with windowed sine burst signals. Due to the nonlinearity in the material law, the waves are not only observed at the excitation frequency, but also at higher harmonic frequencies. Excitation at especially selected frequencies evoke the cumulative effect, and thus gives rise to the amplitudes of the higher harmonics. Comparing the S1-S2 and S2-S4 mode pairs clearly show the higher sensitivity of the latter to the material nonlinearity. This matches with previous published experimental results. Finally, it is shown that the results obtained agree qualitatively well with numerical analyses, in which the micro-structural damages are modeled directly by a respective finite element discretization.

  9. Designing of sparse 2D arrays for Lamb wave imaging using coarray concept

    NASA Astrophysics Data System (ADS)

    Ambroziński, Łukasz; Stepinski, Tadeusz; Uhl, Tadeusz

    2015-03-01

    2D ultrasonic arrays have considerable application potential in Lamb wave based SHM systems, since they enable equivocal damage imaging and even in some cases wave-mode selection. Recently, it has been shown that the 2D arrays can be used in SHM applications in a synthetic focusing (SF) mode, which is much more effective than the classical phase array mode commonly used in NDT. The SF mode assumes a single element excitation of subsequent transmitters and off-line processing the acquired data. In the simplest implementation of the technique, only single multiplexed input and output channels are required, which results in significant hardware simplification. Application of the SF mode for 2D arrays creates additional degrees of freedom during the design of the array topology, which complicates the array design process, however, it enables sparse array designs with performance similar to that of the fully populated dense arrays. In this paper we present the coarray concept to facilitate synthesis process of an array's aperture used in the multistatic synthetic focusing approach in Lamb waves-based imaging systems. In the coherent imaging, performed in the transmit/receive mode, the sum coarray is a morphological convolution of the transmit/receive sub-arrays. It can be calculated as the set of sums of the individual sub-arrays' elements locations. The coarray framework will be presented here using a an example of a star-shaped array. The approach will be discussed in terms of beampatterns of the resulting imaging systems. Both simulated and experimental results will be included.

  10. Designing of sparse 2D arrays for Lamb wave imaging using coarray concept

    SciTech Connect

    Ambroziński, Łukasz Stepinski, Tadeusz Uhl, Tadeusz

    2015-03-31

    2D ultrasonic arrays have considerable application potential in Lamb wave based SHM systems, since they enable equivocal damage imaging and even in some cases wave-mode selection. Recently, it has been shown that the 2D arrays can be used in SHM applications in a synthetic focusing (SF) mode, which is much more effective than the classical phase array mode commonly used in NDT. The SF mode assumes a single element excitation of subsequent transmitters and off-line processing the acquired data. In the simplest implementation of the technique, only single multiplexed input and output channels are required, which results in significant hardware simplification. Application of the SF mode for 2D arrays creates additional degrees of freedom during the design of the array topology, which complicates the array design process, however, it enables sparse array designs with performance similar to that of the fully populated dense arrays. In this paper we present the coarray concept to facilitate synthesis process of an array’s aperture used in the multistatic synthetic focusing approach in Lamb waves-based imaging systems. In the coherent imaging, performed in the transmit/receive mode, the sum coarray is a morphological convolution of the transmit/receive sub-arrays. It can be calculated as the set of sums of the individual sub-arrays’ elements locations. The coarray framework will be presented here using a an example of a star-shaped array. The approach will be discussed in terms of beampatterns of the resulting imaging systems. Both simulated and experimental results will be included.

  11. Imaging of Lamb Waves in Plates for Quantitative Determination of Anisotropy using Photorefractive Dynamic Holography

    SciTech Connect

    Telschow, Kenneth Louis; Deason, Vance Albert; Schley, Robert Scott; Watson, Scott Marshall

    1998-06-01

    Anisotropic properties of sheet materials can be determined by measuring the propagation of Lamb waves in different directions. Electromagnetic acoustic transduction and laser ultrasonic methods provide noncontacting approaches that are often desired for application to industrial and processing environments. This paper describes a laser imaging approach utilizing the adaptive property of photorefractive materials to produce a real-time measurement of the antisymmetric Lamb wave mode in all directions simultaneously. Continuous excitation is employed enabling the data to be recorded and displayed by a CCD camera. Analysis of the image produces a direct quantitative determination of the phase velocity in all directions showing plate anisotropy in the plane. Many optical techniques for measuring ultrasonic motion at surfaces have been developed for use in applications such as vibration measurement and laser ultrasonics. Most of these methods have similar sensitivities and are based on time domain processing using homodyne, Fabry-Perot [1], and, more recently, photorefractive interferometry [2]. Generally, the methods described above do not allow measurement at more than one surface point simultaneously, requiring multiple beam movements and scanning in order to produce images of surface ultrasonic motion over a large area. Electronic speckle interferometry, including shearography, does provide images directly of vibrations over large surface areas. This method has proven very durable in the field for large displacement amplitudes of several wavelengths. In addition, a sensitivity of ë/3000 has been demonstrated under laboratory conditions [3]. Full-field imaging of traveling ultrasonic waves using digital shearography has been recently reported with sensitivity in the nanometer range [4]. With this method, optical interference occurs at the photodetector

  12. Numerical Simulation of Nonlinear Lamb Waves Used in a Thin Plate for Detecting Buried Micro-Cracks

    PubMed Central

    Wan, Xiang; Zhang, Qing; Xu, Guanghua; Tse, Peter W.

    2014-01-01

    Compared with conventional linear ultrasonic inspection methods, which are sensitive only to severe defects, nonlinear ultrasonic inspection methods are better for revealing micro-cracks in thin plates. However, most nonlinear ultrasonic inspection methods have only been experimentally investigated using bulk or Rayleigh waves. Numerical studies, especially numerical simulations of Lamb ultrasonic waves, have seldom been reported. In this paper, the interaction between nonlinear S0 mode Lamb waves and micro-cracks of various lengths and widths buried in a thin metallic plate was simulated using the finite element method (FEM). The numerical results indicate that after interacting with a micro-crack, a new wave-packet was generated in addition to the S0 mode wave-packet. The second harmonics of the S0 mode Lamb waves and the new wave-packet were caused by nonlinear acoustic effects at the micro-crack. An amplitude ratio indicator is thus proposed for the early detection of buried micro-cracks. PMID:24834908

  13. Minimum variance imaging based on correlation analysis of Lamb wave signals.

    PubMed

    Hua, Jiadong; Lin, Jing; Zeng, Liang; Luo, Zhi

    2016-08-01

    In Lamb wave imaging, MVDR (minimum variance distortionless response) is a promising approach for the detection and monitoring of large areas with sparse transducer network. Previous studies in MVDR use signal amplitude as the input damage feature, and the imaging performance is closely related to the evaluation accuracy of the scattering characteristic. However, scattering characteristic is highly dependent on damage parameters (e.g. type, orientation and size), which are unknown beforehand. The evaluation error can degrade imaging performance severely. In this study, a more reliable damage feature, LSCC (local signal correlation coefficient), is established to replace signal amplitude. In comparison with signal amplitude, one attractive feature of LSCC is its independence of damage parameters. Therefore, LSCC model in the transducer network could be accurately evaluated, the imaging performance is improved subsequently. Both theoretical analysis and experimental investigation are given to validate the effectiveness of the LSCC-based MVDR algorithm in improving imaging performance. PMID:27155349

  14. Application of a Lamb waves based technique for structural health monitoring of GFRP undercyclic loading

    NASA Astrophysics Data System (ADS)

    Eremin, A.; Byakov, A.; Panin, S.; Burkov, M.; Lyubutin, P.; Sunder, R.

    2016-04-01

    A Lamb wave based ultrasonic technique as well as optical image characterization was utilized to estimate a current mechanical state of glass fiber reinforced polymers (GFRP) under cyclic tension. The ultrasonic acoustic method was applied in a 'pitch-catch' mode using piezoelectric transducers adhesively bonded onto a specimen surface. Numerical evaluation of acoustic data was performed by calculating two informative parameters: maximum of amplitude of the received signal and variance of signal envelopes. Optical images were registered and then analysed by calculating Shannon entropy that makes it possible to characterize changing of GFRP specimen translucency. The obtained results were treated in order to find out the relation between the current mechanical state of a specimen and informative parameter values being computed from the acoustic and optical signals.

  15. Analysis of transient Lamb waves on metal plates, composite panels and curved members

    NASA Astrophysics Data System (ADS)

    Schumacher, N. A.; Gien, P. H.; Burger, C. P.

    Results of a series of experiments conducted with a laser and fiber-optic-based system for both the generation and detection of transient Lamb waves in a steel plate, a unidirectional composite panel, and a section of seam welded stainless steel tubing are reported. A method for obtaining phase velocity information from FFTs, developed by Sachse & Pao (1978) is used to extract the phase velocity information. In the case of the steel plate, the experimental data are compared to the theoretical results from closed form solutions by Viktorov (1967). It is also demonstrated that the two-channel interferometer provides an excellent source for noncontact 'point' measurements of displacement time histories. When these interferometers are used in pairs, phase velocity for several types of acoustic signals can be extracted from the displacement time histories.

  16. Numerical and experimental studies of delamination detection in short fiber reinforced composites using Lamb waves

    NASA Astrophysics Data System (ADS)

    Kudela, Pawel; Radzienski, Maciej; Ostachowicz, Wieslaw

    2016-04-01

    The aim of this paper is to present aspects of Lamb wave propagation in randomly oriented short fiber reinforce composites with delamination. Prediction of elastic constants is based on mechanics of composites, rule of mixture and total mass balance tailored to the spectral element mesh composed of 3D brick elements. Piezoelectric excitation as well as glue layer are taken into account. Complex full wave field includes multiple reflections at short fibers. This wave pattern is also obtained by the use of laser vibrometry confirming good quality of the model. Further studies are related to symmetrical and non-symmetrical delamination in respect to the thickness of the composite plate. Square delamination of the side length 10 mm is investigated. It has been found that reflections from delamination are mostly superimposed with reflections coming from short fibers. Hence, delamination detection by direct analysis of wave propagation pattern on the surface of the plate is ineffective. However, adaptive wavenumber filtering method overcome these difficulties and enables not only to detect the delamination but also is helpful for delamination size estimation. Moreover, the method is more effective if the full wavefield measurements are acquired on the surface of the plate which is closer to the delamination.

  17. Rayleigh–Lamb wave propagation on a fractional order viscoelastic plate

    PubMed Central

    Meral, F. Can; Royston, Thomas J.; Magin, Richard L.

    2011-01-01

    A previous study of the authors published in this journal focused on mechanical wave motion in a viscoelastic material representative of biological tissue [Meral et al., J. Acoust. Soc. Am. 126, 3278–3285 (2009)]. Compression, shear and surface wave motion in and on a viscoelastic halfspace excited by surface and sub-surface sources were considered. It was shown that a fractional order Voigt model, where the rate-dependent damping component that is dependent on the first derivative of time is replaced with a component that is dependent on a fractional derivative of time, resulted in closer agreement with experiment as compared with conventional (integer order) models, such as those of Voigt and Zener. In the present study, this analysis is extended to another configuration and wave type: out-of-plane response of a viscoelastic plate to harmonic anti-symmetric Lamb wave excitation. Theoretical solutions are compared with experimental measurements for a polymeric tissue mimicking phantom material. As in the previous configurations the fractional order modeling assumption improves the match between theory and experiment over a wider frequency range. Experimental complexities in the present study and the reliability of the different approaches for quantifying the shear viscoelastic properties of the material are discussed. PMID:21361459

  18. Broadband attenuation of Lamb waves through a periodic array of thin rectangular junctions

    NASA Astrophysics Data System (ADS)

    Moiseyenko, Rayisa P.; Pennec, Yan; Marchal, Rémi; Bonello, Bernard; Djafari-Rouhani, Bahram

    2014-10-01

    We study theoretically subwavelength physical phenomena, such as resonant transmission and broadband sound shielding for Lamb waves propagating in an acoustic metamaterial made of a thin plate drilled with one or two row(s) of rectangular holes. The resonances and antiresonances of periodically arranged rectangular junctions separated by holes are investigated as a function of the geometrical parameters of the junctions. With one and two row(s) of holes, high frequency specific features in the transmission coefficient are explained in terms of a coupling of incident waves with both Fabry-Perot oscillations inside the junctions and induced surface acoustic waves between the homogeneous part of the plate and the row of holes. With two rows of holes, low frequency peaks and dips appear in the transmission spectrum. The choice of the distance between the two rows of holes allows the realization of a broadband low frequency acoustic shielding with attenuation over 99% for symmetric waves in a wide low frequency range and over 90% for antisymmetric ones. The origin of the transmission gap is discussed in terms of localized modes of the "H" element made by the junctions, connecting the two homogeneous parts of the plate.

  19. Lamb Wave Stiffness Characterization of Composites Undergoing Thermal-Mechanical Aging

    NASA Technical Reports Server (NTRS)

    Seale, Michael D.; Madaras, Eric I.

    2004-01-01

    The introduction of new, advanced composite materials into aviation systems requires a thorough understanding of the long term effects of combined thermal and mechanical loading upon those materials. Analytical methods investigating the effects of intense thermal heating combined with mechanical loading have been investigated. The damage mechanisms and fatigue lives were dependent on test parameters as well as stress levels. Castelli, et al. identified matrix dominated failure modes for out-of-phase cycling and fiber dominated damage modes for in-phase cycling. In recent years, ultrasonic methods have been developed that can measure the mechanical stiffness of composites. To help evaluate the effect of aging, a suitably designed Lamb wave measurement system is being used to obtain bending and out-of-plane stiffness coefficients of composite laminates undergoing thermal-mechanical loading. The system works by exciting an antisymmetric Lamb wave and calculating the velocity at each frequency from the known transducer separation and the measured time-of-flight. The same peak in the waveforms received at various distances is used to measure the time difference between the signals. The velocity measurements are accurate and repeatable to within 1% resulting in reconstructed stiffness values repeatable to within 4%. Given the material density and plate thickness, the bending and out-of-plane shear stiffnesses are calculated from a reconstruction of the dispersion curve. A mechanical scanner is used to move the sensors over the surface to map the time-of-flight, velocity, or stiffnesses of the entire specimen. Access to only one side of the material is required and no immersion or couplants are required because the sensors are dry coupled to the surface of the plate. In this study, the elastic stiffnesses D(sub 11), D(sub 22), A(sub 44), and A(sub 55) as well as time-of-flight measurements for composite samples that have undergone combined thermal and mechanical aging for

  20. Kelvin waves and the singular modes of the Lamb Oseen vortex

    NASA Astrophysics Data System (ADS)

    Fabre, David; Sipp, Denis; Jacquin, Laurent

    2006-03-01

    Columnar vortices are known to support a family of waves initially discovered by Lord Kelvin (1880) in the case of the Rankine vortex model. This paper presents an exhaustive cartography of the eigenmodes of a more realistic vortex model, the Lamb Oseen vortex. Some modes are Kelvin waves related to those existing in the Rankine vortex, while some others are singular damped modes with a completely different nature. Several families are identified and are successively described. For each family, the underlying physical mechanism is explained, and the effect of viscosity is detailed. In the axisymmetric case (with azimuthal wavenumber m {=} 0), all modes are Kelvin waves and weakly affected by viscosity. For helical modes (m {=} 1), four families are identified. The first family, denoted D, corresponds to a particular wave called the displacement wave. The modes of the second family, denoted C, are cograde waves, except in the long-wave range where they become centre modes and are strongly affected by viscosity. The modes of the third family, denoted V, are retrograde, singular modes which are always strongly damped and do not exist in the inviscid limit. The modes of the last family, denoted L, are regular, counter-rotating waves for short wavelengths, but they become singular damped modes for long wavelengths. In an intermediate range of wavelengths between these two limits, they display a particular structure, with both a wave-like profile within the vortex core and a spiral structure at its periphery. This kind of mode is called a critical layer wave, and its significance is explained from both a physical and a mathematical point of view. Double-helix modes (m {=} 2) can similarly be classified into the C, V and L families. One additional mode, called F, plays a particular role. For short wavelenghs, this mode corresponds to a helical flattening wave, and has a clear physical significance. However, for long wavelenghts, this mode completely changes its structure

  1. Lamb mode selection for accurate wall loss estimation via guided wave tomography

    SciTech Connect

    Huthwaite, P.; Ribichini, R.; Lowe, M. J. S.; Cawley, P.

    2014-02-18

    Guided wave tomography offers a method to accurately quantify wall thickness losses in pipes and vessels caused by corrosion. This is achieved using ultrasonic waves transmitted over distances of approximately 1–2m, which are measured by an array of transducers and then used to reconstruct a map of wall thickness throughout the inspected region. To achieve accurate estimations of remnant wall thickness, it is vital that a suitable Lamb mode is chosen. This paper presents a detailed evaluation of the fundamental modes, S{sub 0} and A{sub 0}, which are of primary interest in guided wave tomography thickness estimates since the higher order modes do not exist at all thicknesses, to compare their performance using both numerical and experimental data while considering a range of challenging phenomena. The sensitivity of A{sub 0} to thickness variations was shown to be superior to S{sub 0}, however, the attenuation from A{sub 0} when a liquid loading was present was much higher than S{sub 0}. A{sub 0} was less sensitive to the presence of coatings on the surface of than S{sub 0}.

  2. Lamb mode selection for accurate wall loss estimation via guided wave tomography

    NASA Astrophysics Data System (ADS)

    Huthwaite, P.; Ribichini, R.; Lowe, M. J. S.; Cawley, P.

    2014-02-01

    Guided wave tomography offers a method to accurately quantify wall thickness losses in pipes and vessels caused by corrosion. This is achieved using ultrasonic waves transmitted over distances of approximately 1-2m, which are measured by an array of transducers and then used to reconstruct a map of wall thickness throughout the inspected region. To achieve accurate estimations of remnant wall thickness, it is vital that a suitable Lamb mode is chosen. This paper presents a detailed evaluation of the fundamental modes, S0 and A0, which are of primary interest in guided wave tomography thickness estimates since the higher order modes do not exist at all thicknesses, to compare their performance using both numerical and experimental data while considering a range of challenging phenomena. The sensitivity of A0 to thickness variations was shown to be superior to S0, however, the attenuation from A0 when a liquid loading was present was much higher than S0. A0 was less sensitive to the presence of coatings on the surface of than S0.

  3. Lamb wave dispersion in a PZT/metal/PZT sandwich plate with imperfect interface

    NASA Astrophysics Data System (ADS)

    Kurt, Ilkay; Akbarov, Surkay D.; Sezer, Semih

    2016-07-01

    The Lamb wave dispersion in a PZT/Metal/PZT sandwich plate is investigated by employing the exact linear equations of electro-elastic waves in piezoelectric materials within the scope of the plane-strain state. It is assumed that at the interfaces between the piezoelectric face layers and metal core layer, shear-spring and normal-spring type imperfect conditions are satisfied. The degree of this imperfectness is estimated through the corresponding shear-spring and normal-spring type parameters which appear in the contact condition characterizing the transverse and normal displacements' discontinuity. The corresponding dispersion equation is derived, and as a result of the numerical solution to this equation, the dispersion curves are constructed for the first and second lowest modes in the cases where the material of the face layers is PZT and the material of the middle layer is Steel (St). Consequently, for the PZT/St/PZT sandwich plate, the study of the influence of the problem parameters such as the piezoelectric and dielectric constants, layer thickness ratios, non-dimensional shear-spring, and normal-spring type parameters, is carried out. In particular, it is established that the imperfectness of the contact between the layers of the plate causes a decrease in the values of the wave propagation velocity.

  4. Symmetry issues in the hybridization of multi-mode waves with resonators: an example with Lamb waves metamaterial

    NASA Astrophysics Data System (ADS)

    Rupin, Matthieu; Roux, Philippe; Lerosey, Geoffroy; Lemoult, Fabrice

    2015-09-01

    Locally resonant metamaterials derive their effective properties from hybridization between their resonant unit cells and the incoming wave. This phenomenon is well understood in the case of plane waves that propagate in media where the unit cell respects the symmetry of the incident field. However, in many systems, several modes with orthogonal symmetries can coexist at a given frequency, while the resonant unit cells themselves can have asymmetric scattering cross-sections. In this paper we are interested in the influence of symmetry breaking on the hybridization of a wave field that includes multiple propagative modes. The A0 and S0 Lamb waves that propagate in a thin plate are good candidates for this study, as they are either anti-symmetric or symmetric. First we designed an experimental setup with an asymmetric metamaterial made of long rods glued to one side of a metallic plate. We show that the flexural resonances of the rods induce a break of the orthogonality between the A0/S0 modes of the free-plate. Finally, based on numerical simulations we show that the orthogonality is preserved in the case of a symmetric metamaterial leading to the presence of two independent polariton curves in the dispersion relation.

  5. Symmetry issues in the hybridization of multi-mode waves with resonators: an example with Lamb waves metamaterial.

    PubMed

    Rupin, Matthieu; Roux, Philippe; Lerosey, Geoffroy; Lemoult, Fabrice

    2015-01-01

    Locally resonant metamaterials derive their effective properties from hybridization between their resonant unit cells and the incoming wave. This phenomenon is well understood in the case of plane waves that propagate in media where the unit cell respects the symmetry of the incident field. However, in many systems, several modes with orthogonal symmetries can coexist at a given frequency, while the resonant unit cells themselves can have asymmetric scattering cross-sections. In this paper we are interested in the influence of symmetry breaking on the hybridization of a wave field that includes multiple propagative modes. The A0 and S0 Lamb waves that propagate in a thin plate are good candidates for this study, as they are either anti-symmetric or symmetric. First we designed an experimental setup with an asymmetric metamaterial made of long rods glued to one side of a metallic plate. We show that the flexural resonances of the rods induce a break of the orthogonality between the A0/S0 modes of the free-plate. Finally, based on numerical simulations we show that the orthogonality is preserved in the case of a symmetric metamaterial leading to the presence of two independent polariton curves in the dispersion relation. PMID:26333601

  6. Symmetry issues in the hybridization of multi-mode waves with resonators: an example with Lamb waves metamaterial

    PubMed Central

    Rupin, Matthieu; Roux, Philippe; Lerosey, Geoffroy; Lemoult, Fabrice

    2015-01-01

    Locally resonant metamaterials derive their effective properties from hybridization between their resonant unit cells and the incoming wave. This phenomenon is well understood in the case of plane waves that propagate in media where the unit cell respects the symmetry of the incident field. However, in many systems, several modes with orthogonal symmetries can coexist at a given frequency, while the resonant unit cells themselves can have asymmetric scattering cross-sections. In this paper we are interested in the influence of symmetry breaking on the hybridization of a wave field that includes multiple propagative modes. The A0 and S0 Lamb waves that propagate in a thin plate are good candidates for this study, as they are either anti-symmetric or symmetric. First we designed an experimental setup with an asymmetric metamaterial made of long rods glued to one side of a metallic plate. We show that the flexural resonances of the rods induce a break of the orthogonality between the A0/S0 modes of the free-plate. Finally, based on numerical simulations we show that the orthogonality is preserved in the case of a symmetric metamaterial leading to the presence of two independent polariton curves in the dispersion relation. PMID:26333601

  7. Lamb wave feature extraction using discrete wavelet transformation and Principal Component Analysis

    NASA Astrophysics Data System (ADS)

    Ghodsi, Mojtaba; Ziaiefar, Hamidreza; Amiryan, Milad; Honarvar, Farhang; Hojjat, Yousef; Mahmoudi, Mehdi; Al-Yahmadi, Amur; Bahadur, Issam

    2016-04-01

    In this research, a new method is presented for eliciting the proper features for recognizing and classifying the kinds of the defects by guided ultrasonic waves. After applying suitable preprocessing, the suggested method extracts the base frequency band from the received signals by discrete wavelet transform and discrete Fourier transform. This frequency band can be used as a distinctive feature of ultrasonic signals in different defects. Principal Component Analysis with improving this feature and decreasing extra data managed to improve classification. In this study, ultrasonic test with A0 mode lamb wave is used and is appropriated to reduce the difficulties around the problem. The defects under analysis included corrosion, crack and local thickness reduction. The last defect is caused by electro discharge machining (EDM). The results of the classification by optimized Neural Network depicts that the presented method can differentiate different defects with 95% precision and thus, it is a strong and efficient method. Moreover, comparing the elicited features for corrosion and local thickness reduction and also the results of the two's classification clarifies that modeling the corrosion procedure by local thickness reduction which was previously common, is not an appropriate method and the signals received from the two defects are different from each other.

  8. CMOS-compatible ruggedized high-temperature Lamb wave pressure sensor

    NASA Astrophysics Data System (ADS)

    Kropelnicki, P.; Muckensturm, K.-M.; Mu, X. J.; Randles, A. B.; Cai, H.; Ang, W. C.; Tsai, J. M.; Vogt, H.

    2013-08-01

    This paper describes the development of a novel ruggedized high-temperature pressure sensor operating in lateral field exited (LFE) Lamb wave mode. The comb-like structure electrodes on top of aluminum nitride (AlN) were used to generate the wave. A membrane was fabricated on SOI wafer with a 10 µm thick device layer. The sensor chip was mounted on a pressure test package and pressure was applied to the backside of the membrane, with a range of 20-100 psi. The temperature coefficient of frequency (TCF) was experimentally measured in the temperature range of -50 °C to 300 °C. By using the modified Butterworth-van Dyke model, coupling coefficients and quality factor were extracted. Temperature-dependent Young's modulus of composite structure was determined using resonance frequency and sensor interdigital transducer (IDT) wavelength which is mainly dominated by an AlN layer. Absolute sensor phase noise was measured at resonance to estimate the sensor pressure and temperature sensitivity. This paper demonstrates an AlN-based pressure sensor which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications.

  9. Characterization of Degradation Progressive in Composite Laminates Subjected to Thermal Fatigue and Moisture Diffusion by Lamb Waves.

    PubMed

    Li, Weibin; Xu, Chunguang; Cho, Younho

    2016-01-01

    Laminate composites which are widely used in the aeronautical industry, are usually subjected to frequency variation of environmental temperature and excessive humidity in the in-service environment. The thermal fatigue and moisture absorption in composites may induce material degradation. There is a demand to investigate the coupling damages mechanism and characterize the degradation evolution of composite laminates for the particular application. In this paper, the degradation evolution in unidirectional carbon/epoxy composite laminates subjected to thermal fatigue and moisture absorption is characterized by Lamb waves. The decrease rate of Lamb wave velocity is used to track the degradation evolution in the specimens. The results show that there are two stages for the progressive degradation of composites under the coupling effect of thermal cyclic loading and moisture diffusion. The present work provides an alternative to monitoring the degradation evolution of in-service aircraft composite Laminates. PMID:26907283

  10. Characterization of Degradation Progressive in Composite Laminates Subjected to Thermal Fatigue and Moisture Diffusion by Lamb Waves

    PubMed Central

    Li, Weibin; Xu, Chunguang; Cho, Younho

    2016-01-01

    Laminate composites which are widely used in the aeronautical industry, are usually subjected to frequency variation of environmental temperature and excessive humidity in the in-service environment. The thermal fatigue and moisture absorption in composites may induce material degradation. There is a demand to investigate the coupling damages mechanism and characterize the degradation evolution of composite laminates for the particular application. In this paper, the degradation evolution in unidirectional carbon/epoxy composite laminates subjected to thermal fatigue and moisture absorption is characterized by Lamb waves. The decrease rate of Lamb wave velocity is used to track the degradation evolution in the specimens. The results show that there are two stages for the progressive degradation of composites under the coupling effect of thermal cyclic loading and moisture diffusion. The present work provides an alternative to monitoring the degradation evolution of in-service aircraft composite Laminates. PMID:26907283

  11. Research on a Lamb Wave and Particle Filter-Based On-Line Crack Propagation Prognosis Method.

    PubMed

    Chen, Jian; Yuan, Shenfang; Qiu, Lei; Cai, Jian; Yang, Weibo

    2016-01-01

    Prognostics and health management techniques have drawn widespread attention due to their ability to facilitate maintenance activities based on need. On-line prognosis of fatigue crack propagation can offer information for optimizing operation and maintenance strategies in real-time. This paper proposes a Lamb wave-particle filter (LW-PF)-based method for on-line prognosis of fatigue crack propagation which takes advantages of the possibility of on-line monitoring to evaluate the actual crack length and uses a particle filter to deal with the crack evolution and monitoring uncertainties. The piezoelectric transducers (PZTs)-based active Lamb wave method is adopted for on-line crack monitoring. The state space model relating to crack propagation is established by the data-driven and finite element methods. Fatigue experiments performed on hole-edge crack specimens have validated the advantages of the proposed method. PMID:26950130

  12. Research on a Lamb Wave and Particle Filter-Based On-Line Crack Propagation Prognosis Method

    PubMed Central

    Chen, Jian; Yuan, Shenfang; Qiu, Lei; Cai, Jian; Yang, Weibo

    2016-01-01

    Prognostics and health management techniques have drawn widespread attention due to their ability to facilitate maintenance activities based on need. On-line prognosis of fatigue crack propagation can offer information for optimizing operation and maintenance strategies in real-time. This paper proposes a Lamb wave-particle filter (LW-PF)-based method for on-line prognosis of fatigue crack propagation which takes advantages of the possibility of on-line monitoring to evaluate the actual crack length and uses a particle filter to deal with the crack evolution and monitoring uncertainties. The piezoelectric transducers (PZTs)-based active Lamb wave method is adopted for on-line crack monitoring. The state space model relating to crack propagation is established by the data-driven and finite element methods. Fatigue experiments performed on hole-edge crack specimens have validated the advantages of the proposed method. PMID:26950130

  13. Simulation of Detecting Damage in Composite Stiffened Panel Using Lamb Waves

    NASA Technical Reports Server (NTRS)

    Wang, John T.; Ross, Richard W.; Huang, Guo L.; Yuan, Fuh G.

    2013-01-01

    Lamb wave damage detection in a composite stiffened panel is simulated by performing explicit transient dynamic finite element analyses and using signal imaging techniques. This virtual test process does not need to use real structures, actuators/sensors, or laboratory equipment. Quasi-isotropic laminates are used for the stiffened panels. Two types of damage are studied. One type is a damage in the skin bay and the other type is a debond between the stiffener flange and the skin. Innovative approaches for identifying the damage location and imaging the damage were developed. The damage location is identified by finding the intersection of the damage locus and the path of the time reversal wave packet re-emitted from the sensor nodes. The damage locus is a circle that envelops the potential damage locations. Its center is at the actuator location and its radius is computed by multiplying the group velocity by the time of flight to damage. To create a damage image for estimating the size of damage, a group of nodes in the neighborhood of the damage location is identified for applying an image condition. The image condition, computed at a finite element node, is the zero-lag cross-correlation (ZLCC) of the time-reversed incident wave signal and the time reversal wave signal from the sensor nodes. This damage imaging process is computationally efficient since only the ZLCC values of a small amount of nodes in the neighborhood of the identified damage location are computed instead of those of the full model.

  14. COMSOL modelling of the acoustoelastic effect

    NASA Astrophysics Data System (ADS)

    Watson, N. J.; Hazlehurst, T.; Povey, M. J. W.; Drennan, A.; Seaman, P.

    2015-01-01

    Many structural components are subjected to either constant or temporal mechanical loads, such as a suspension bridge bolts and rail tracks. Methods are required to accurately and efficiently measure the stresses experienced by these components to ensure they can continue to operate in an effective and safe manner. Acoustic techniques can be used to monitor the stress in a solid material via the acoustoelastic effect. This is the stress dependence of the acoustic velocity in an elastic media. This work develops a multiphysics computational model to study the acoustoelastic effect in a three point bending system. A simple linear relationship was utilised to represent the stress effect on the acoustic velocity. The simulation results were compared with experimental results and the same general trend was observed. An increase in applied load resulted in a greater difference between the time of flight of two transducers at the top and bottom of a component and perpendicular to the applied load. However, there were quantitative differences between the model and the experiment. The model was used to investigate different ultrasound transducer location and operating frequency, highlighting the benefit of modelling tools for the design of acoustic equipment.

  15. Precise Measurement of Pipe Wall Thickness in Noncontact Manner Using a Circumferential Lamb Wave Generated and Detected by a Pair of Air-Coupled Transducers

    NASA Astrophysics Data System (ADS)

    Nishino, Hideo; Asano, Tadashi; Taniguchi, Yuta; Yoshida, Kenichi; Ogawa, Hitoshi; Takahashi, Masakazu; Ogura, Yukio

    2011-07-01

    In this paper, we present a novel method of accurately estimating pipe wall thickness by detecting the minute difference in the angular wave number of a circumferential (C-) Lamb wave. A C-Lamb wave circling along a circumference of a pipe is transmitted and received by a pair of noncontact air-coupled ultrasonic transducers. For the accurate detection of the angular wave number, a large number of tone-burst cycles are used so as to superpose the C-Lamb wave on itself along its circumferential orbit. In this setting, the amplitude of the superposed region changes considerably with the angular wave number, from which the wall thickness can be estimated. This method is very useful to monitor the integrity of piping in high-temperature environments because of its noncontact nature. The principle of the method and experimental verification are shown.

  16. Lamb wave ultrasonic evaluation of welded AA2024 specimens at tensile static and fatigue testing

    NASA Astrophysics Data System (ADS)

    Burkov, M. V.; Byakov, A. V.; Shah, R. T.; Lyubutin, P. S.; Panin, S. V.

    2015-10-01

    The paper deals with the investigation of Lamb waves ultrasonic testing technique applied for evaluation of different stress-strain and damaged state of aluminum specimens at static and fatigue loading in order to develop a Structural Health Monitoring (SHM) approach. The experimental results of tensile testing of AA2024T3 specimens with welded joints are presented. Piezoelectric transducers used as actuators and sensors were adhesively bonded to the specimen's surface using two component epoxy. The set of static and cyclic tensile tests with two frequencies of acoustic testing (50 kHz and 335 kHz) were performed. The recorded signals were processed to calculate the maximum envelope in order to evaluate the changes of the stress-strain state of the specimen and its microstructure during static tension. The registered data are analyzed and discussed in terms of signal attenuation due to the formation of fatigue defects during cyclic loading. Understanding the relations between acoustic signal features and fatigue damages will provide us the ability to determine the damage state of the structure and its residual lifetime in order to design a robust SHM system.

  17. Lamb Wave-Based Acoustic Radiation Force-Driven Particle Ring Formation Inside a Sessile Droplet.

    PubMed

    Destgeer, Ghulam; Ha, Byunghang; Park, Jinsoo; Sung, Hyung Jin

    2016-04-01

    We demonstrate an acoustofluidic device using Lamb waves (LWs) to manipulate polystyrene (PS) microparticles suspended in a sessile droplet of water. The LW-based acoustofluidic platform used in this study is advantageous in that the device is actuated over a range of frequencies without changing the device structure or electrode pattern. In addition, the device is simple to operate and cheap to fabricate. The LWs, produced on a piezoelectric substrate, attenuate inside the fluid and create acoustic streaming flow (ASF) in the form of a poloidal flow with toroidal vortices. The PS particles experience direct acoustic radiation force (ARF) in addition to being influenced by the ASF, which drive the concentration of particles to form a ring. This phenomenon was previously attributed to the ASF alone, but the present experimental results confirm that the ARF plays an important role in forming the particle ring, which would not be possible in the presence of only the ASF. We used a range of actuation frequencies (45-280 MHz), PS particle diameters (1-10 μm), and droplet volumes (5, 7.5, and 10 μL) to experimentally demonstrate this phenomenon. PMID:26937678

  18. Design and characterization of an ultrasonic lamb-wave power delivery system.

    PubMed

    Kural, Aleksander; Pullin, Rhys; Holford, Karen; Lees, Jonathan; Naylon, Jack; Paget, Christophe; Featherston, Carol

    2013-06-01

    In this paper, a novel design for an ultrasonic power transmission system designed for use in aircraft structural monitoring systems is described. The prototype system uses ultrasonic Lamb waves to carry energy along plates, such as those used in aircraft structures, and commercially available piezoelectric patch transducers as the transmitter and receiver. This sets it apart from other acoustic power transmission systems reported to date. The optimum configuration transmitted 12.7 mW of power across a distance of 54 cm in a 1.5-mm-thick aluminum plate, while being driven by a 20-Vpp, 35-kHz sinusoidal electric signal. This is in the same order of magnitude as the power required by the wireless sensors nodes of a structural health monitoring system currently being developed by Cardiff University and its partners. Thus, the power transmission system can be considered a viable component of the power source combination considered for the sensor nodes, which will also include vibration and thermal energy harvesting. The paper describes the design and optimization of the transmission and reception circuits with the use of inductive compensation. The use of laser vibrometry to characterize the transducers and to understand the signal propagation between them is also reported. PMID:25004476

  19. Effects of slits in a patch of omnidirectional Lamb-wave MPT on the transducer output

    NASA Astrophysics Data System (ADS)

    Kim, Kiyean; Lee, Hyung Jin; Lee, Joo Kyung; Kim, Yoon Young

    2016-03-01

    An omnidirectional Lamb-wave magnetostrictive patch transducer (MPT) uses a thin circular magnetostrictive patch excited by the axisymmetric turns of a plane coil placed over it. Since the dynamic magnetic field applied by the coil induces an eddy current only on the top surface due to the skin effect, the mechanical deformation in the patch is confined only near the surface, considerably limiting the transducer output power. This study shows that if a radial slit is introduced in the patch, the circular flow of the eddy current on the top surface only becomes broken, and thus the eddy current flows on both the top and bottom surfaces. As a consequence, there is a substantial increase in the dynamic magnetic field in the patch and, in turn, an increased transducer output power. Interestingly, the material type, either metallic or nonmetallic, of the test waveguide plate affects the magnitude of the eddy current near the bottom surface and the overall magnetic field. If the number of slits is over a certain number, say, 8, and the slits are symmetrically made in the patch, the omni-directivity of the resulting MPT is virtually ensured. Finally, the present findings are verified both numerically and experimentally.

  20. Lamb-wave (X, Y) giant tap screen panel with built-in microphone and loudspeaker.

    PubMed

    Nikolovski, Jean-Pierre

    2013-06-01

    This paper presents a passive (X, Y) giant tap screen panel (GTP). Based on the time difference of arrival principle (TDOA), the device localizes low-energy impacts of around 1 mJ generated by fingernail taps. Selective detection of A0 Lamb waves generated in the upper frequency spectrum, around 100 kHz, makes it possible to detect light to strong impacts with equal resolution or precision, close to 1 cm and 2 mm, respectively, for a 10-mm-thick and 1-m(2) glass plate. Additionally, with glass, symmetrical beveling of the edges is used to create a tsunami effect that reduces the minimum impacting speed for light taps by a factor of three. Response time is less than 1 ms. Maximum panel size is of the order of 10 m(2). A rugged integrated flat design with embedded transducers in an electrically shielding frame features waterproof and sticker/ tag proof operation. Sophisticated electronics with floating amplification maintains the panel at its maximum possible sensitivity according to the surrounding noise. Amplification and filtering turns the panel into a microphone and loudspeaker featuring 50 mV/Pa as a microphone and up to 80 dBlin between 500 Hz and 8 kHz as a loudspeaker. PMID:25004480

  1. Experimental and theoretical study of Rayleigh-Lamb waves in a plate containing a surface-breaking crack

    NASA Technical Reports Server (NTRS)

    Paffenholz, Joseph; Fox, Jon W.; Gu, Xiaobai; Jewett, Greg S.; Datta, Subhendu K.

    1990-01-01

    Scattering of Rayleigh-Lamb waves by a normal surface-breaking crack in a plate has been studied both theoretically and experimentally. The two-dimensionality of the far field, generated by a ball impact source, is exploited to characterize the source function using a direct integration technique. The scattering of waves generated by this impact source by the crack is subsequently solved by employing a Green's function integral expression for the scattered field coupled with a finite element representation of the near field. It is shown that theoretical results of plate response, both in frequency and time, are similar to those obtained experimentally. Additionally, implication for practical applications are discussed.

  2. On the acoustoelasticity of polycrystalline materials.

    PubMed

    Kube, Christopher M; Arguelles, Andrea; Turner, Joseph A

    2015-09-01

    A linear relation between the strains and stresses of a crystallite within a polycrystal is used to homogenize the polycrystal's elastic properties. The homogenization parallels the self-consistent method that is used for estimating the polycrystal's linear elastic properties. Acoustoelasticity for a macroscopically isotropic polycrystal is then formulated using a homogenized constitutive equation with initial stress. Simple expressions are given for the phase velocities and polarization directions for a uniaxially stressed polycrystal. The present model is compared with the model of Man and Paroni [J. Elast. 45, 91-116 (1996)]. Strong anisotropy of the crystallite elastic constants causes the present model to differ noticeably from the model of Man and Paroni. PMID:26428787

  3. A quantitative method for evaluating numerical simulation accuracy of time-transient Lamb wave propagation with its applications to selecting appropriate element size and time step.

    PubMed

    Wan, Xiang; Xu, Guanghua; Zhang, Qing; Tse, Peter W; Tan, Haihui

    2016-01-01

    Lamb wave technique has been widely used in non-destructive evaluation (NDE) and structural health monitoring (SHM). However, due to the multi-mode characteristics and dispersive nature, Lamb wave propagation behavior is much more complex than that of bulk waves. Numerous numerical simulations on Lamb wave propagation have been conducted to study its physical principles. However, few quantitative studies on evaluating the accuracy of these numerical simulations were reported. In this paper, a method based on cross correlation analysis for quantitatively evaluating the simulation accuracy of time-transient Lamb waves propagation is proposed. Two kinds of error, affecting the position and shape accuracies are firstly identified. Consequently, two quantitative indices, i.e., the GVE (group velocity error) and MACCC (maximum absolute value of cross correlation coefficient) derived from cross correlation analysis between a simulated signal and a reference waveform, are proposed to assess the position and shape errors of the simulated signal. In this way, the simulation accuracy on the position and shape is quantitatively evaluated. In order to apply this proposed method to select appropriate element size and time step, a specialized 2D-FEM program combined with the proposed method is developed. Then, the proper element size considering different element types and time step considering different time integration schemes are selected. These results proved that the proposed method is feasible and effective, and can be used as an efficient tool for quantitatively evaluating and verifying the simulation accuracy of time-transient Lamb wave propagation. PMID:26315506

  4. Lamb wave dispersion and anisotropy profiling of composite plates via non-contact air-coupled and laser ultrasound

    NASA Astrophysics Data System (ADS)

    Harb, M. S.; Yuan, F. G.

    2015-03-01

    Conventional ultrasound inspection has been a standard non-destructive testing method for providing an in-service evaluation and noninvasive means of probing the interior of a structure. In particular, measurement of the propagation characteristics of Lamb waves allows inspection of plates that are typical components in aerospace industry. A rapid, complete non-contact hybrid approach for excitation and detection of Lamb waves is presented and applied for non-destructive evaluation of composites. An air-coupled transducer (ACT) excites ultrasonic waves on the surface of a composite plate, generating different propagating Lamb wave modes and a laser Doppler vibrometer (LDV) is used to measure the out-of-plane velocity of the plate. This technology, based on direct waveform imaging, focuses on measuring dispersive curves for A0 mode in a composite laminate and its anisotropy. A two-dimensional fast Fourier transform (2D-FFT) is applied to out-of-plane velocity data captured experimentally using LDV to go from the time-spatial domain to frequency-wavenumber domain. The result is a 2D array of amplitudes at discrete frequencies and wavenumbers for A0 mode in a given propagation direction along the composite. The peak values of the curve are then used to construct frequency wavenumber and phase velocity dispersion curves, which are also obtained directly using Snell's law and the incident angle of the excited ultrasonic waves. A high resolution and strong correlation between numerical and experimental results are observed for dispersive curves with Snell's law method in comparison to 2D-FFT method. Dispersion curves as well as velocity curves for the composite plate along different directions of wave propagation are measured. The visual read-out of the dispersion curves at different propagation directions as well as the phase velocity curves provide profiling and measurements of the composite anisotropy. The results proved a high sensitivity of the air-coupled and laser

  5. A New Omni-Directional EMAT for Ultrasonic Lamb Wave Tomography Imaging of Metallic Plate Defects

    PubMed Central

    Huang, Songling; Wei, Zheng; Zhao, Wei; Wang, Shen

    2014-01-01

    This paper proposes a new omni-directional electromagnetic acoustic transducer (EMAT) for the ultrasonic Lamb wave (ULW) tomography imaging (TI) of defects in metallic plates. The proposed EMAT is composed of a permanent magnet and a coil with a contra-flexure structure. This new EMAT coil structure is used for omni-directional ULW transmission and reception and ULW TI for the first time. The theoretical background and the working principles of this EMAT are presented and analyzed. The experimental results of its use on a 3 mm thick aluminum plate indicate that the EMAT with a contra-flexure coil (CFC) can transmit and receive a pure single A0 mode ULW with a high signal-to-noise ratio (SNR). Thus, the extraction of the projection data used for ULW TI may be performed accurately. The circumferential consistency of the projection data is only slightly influenced by the distortion of the eddy current field that is induced by the new CFC with an irregular shape. When the new EMAT array is used for ULW TI using the cross-hole method and SIRT arithmetic, a desirable imaging quality can be achieved, and the estimated size of an artificial corrosion defect agreed well with its actual value. The relation between the reconstruction resolution and the number of the new EMATs used is analyzed. More TI experiments are carried out when the aluminum plate defect is in two different locations relative to the EMAT array, for the further investigation of the performances of the new EMATs. PMID:24561398

  6. A new omni-directional EMAT for ultrasonic Lamb wave tomography imaging of metallic plate defects.

    PubMed

    Huang, Songling; Wei, Zheng; Zhao, Wei; Wang, Shen

    2014-01-01

    This paper proposes a new omni-directional electromagnetic acoustic transducer (EMAT) for the ultrasonic Lamb wave (ULW) tomography imaging (TI) of defects in metallic plates. The proposed EMAT is composed of a permanent magnet and a coil with a contra-flexure structure. This new EMAT coil structure is used for omni-directional ULW transmission and reception and ULW TI for the first time. The theoretical background and the working principles of this EMAT are presented and analyzed. The experimental results of its use on a 3 mm thick aluminum plate indicate that the EMAT with a contra-flexure coil (CFC) can transmit and receive a pure single A0 mode ULW with a high signal-to-noise ratio (SNR). Thus, the extraction of the projection data used for ULW TI may be performed accurately. The circumferential consistency of the projection data is only slightly influenced by the distortion of the eddy current field that is induced by the new CFC with an irregular shape. When the new EMAT array is used for ULW TI using the cross-hole method and SIRT arithmetic, a desirable imaging quality can be achieved, and the estimated size of an artificial corrosion defect agreed well with its actual value. The relation between the reconstruction resolution and the number of the new EMATs used is analyzed. More TI experiments are carried out when the aluminum plate defect is in two different locations relative to the EMAT array, for the further investigation of the performances of the new EMATs. PMID:24561398

  7. Hysteretic nonlinear elasticity of Berea sandstone at low-vibrational strain revealed by dynamic acousto-elastic testing

    NASA Astrophysics Data System (ADS)

    Renaud, G.; RivièRe, J.; Le Bas, P.-Y.; Johnson, P. A.

    2013-02-01

    Abstract Through changes in <span class="hlt">wave</span> speed of ultrasonic pulses traversing the sample, we measure variations in the elasticity of dry Berea sandstone as a function of the applied low-frequency (LF) axial strain (varied from 10-7 to 10-5). The approach, termed dynamic <span class="hlt">acousto-elasticity</span>, is the dynamic analog of static <span class="hlt">acousto-elasticity</span> where the <span class="hlt">wave</span> speed is measured as a function of the applied static load. Dynamic <span class="hlt">acousto-elasticity</span> uses low-frequency vibrational loading of smaller strain amplitude, typically below 10-4, and it includes inertial effects. At strain amplitudes around 10-6, compression and tension produce a material softening of the material. In contrast, a quasi-static compression inducing a strain between 10-4 and 10-3 leads to a material stiffening. At 10-5 strain amplitude, elaborate hysteretic signatures of modulus strain are observed. The measurements provide the first direct experimental evidence of hysteretic nonlinear (<span class="hlt">wave</span> amplitude dependent) elasticity in a sandstone at low dynamic strains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JaJAP..37.3110M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JaJAP..37.3110M"><span id="translatedtitle">A Simplified Elastic Stiffness Estimation of Unidirectional Carbon-Fiber-Reinforced Coupon Using the In-Plane Velocity Anisotropy of <span class="hlt">Lamb</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mizutani, Yoshihiro; Takemoto, Mikio</p> <p>1998-05-01</p> <p>We propose a simplified method for estimating thefive elastic stiffnesses of a unidirectionalcarbon-fiber-reinforced plastic (UD-CFRP) coupon from the velocity anisotropy of laser-excited <span class="hlt">Lamb</span> <span class="hlt">waves</span>. This method utilizes the in-plane orientation dependence of the Rayleigh <span class="hlt">wave</span> velocities which are estimated from the velocity dispersions of thezero-th-order antisymmetric <span class="hlt">Lamb</span> (A0-<span class="hlt">Lamb</span>) <span class="hlt">wave</span>. We estimated the five elastic stiffnesses of UD-CFRP couponsby utilizing the simplex-assisted inverse scheme, andcompared the obtained values with those determined by the strain gauge method. The proposed method was found to beeffective for estimating the stiffnesses of anisotropicmaterials. However, the inverse scheme must be modifiedto improve the accuracy of measurement of somestiffnesses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AIPC.1096..928K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AIPC.1096..928K"><span id="translatedtitle">Non-Contact Ultrasound Based Guided <span class="hlt">Lamb</span> <span class="hlt">Waves</span> for Composite Structure Inspection: Some Interesting Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karthikeyan, P.; Ramdas, C.; Bhardwaj, Mahesh C.; Balasubramaniam, Krishnan</p> <p>2009-03-01</p> <p>Quality assurance of the composite products becomes important to avoid defects during processing since they are used for critical applications. Non- Contact Ultrasound (NCU) technique using the A0 <span class="hlt">Lamb</span> modes is explored here with applications in the detection, imaging, and sizing of defects in both honeycomb and more importantly composite laminates. A Finite Element Model was employed to understand the interactions of the <span class="hlt">Lamb</span> modes with defects. Mode conversions at the two ends of a delamination and the time of flight differences between these were employed for the determination of the size of the delaminations in composite laminates. This method may allow for the two dimensional sizing of the delaminations in composite laminates using a single line-scan using the <span class="hlt">Lamb</span> modes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APhy...62..165A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APhy...62..165A"><span id="translatedtitle">The anisotropy of the basic characteristics of <span class="hlt">Lamb</span> <span class="hlt">waves</span> in a (001)-Bi12SiO20 piezoelectric crystal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anisimkin, V. I.</p> <p>2016-03-01</p> <p>The orientation dependences of the phase velocity, the effective electromechanical coupling coefficient, and the angle between the <span class="hlt">wave</span> normal and the energy flux vector are numerically calculated for zeroand first-order <span class="hlt">Lamb</span> <span class="hlt">waves</span> propagating in the (001) basal plane of a Bi12SiO20 cubic piezoelectric crystal. It is shown that the anisotropies of these modes are different and depend on the plate thickness h and the wavelength λ. For h/λ < 1, the mode anisotropy can exceed the anisotropy of the corresponding characteristics of surface acoustic <span class="hlt">waves</span> propagating in the same plane; for h/λ > 1, it approximately coincides with the SAW anisotropy for all the characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016SMaS...25h5014I&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016SMaS...25h5014I&link_type=ABSTRACT"><span id="translatedtitle">Effects of adhesive thickness on the <span class="hlt">Lamb</span> <span class="hlt">wave</span> pitch-catch signal using bonded piezoelectric wafer transducers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Islam, M. M.; Huang, H.</p> <p>2016-08-01</p> <p>This paper investigates the effects of adhesive layer on <span class="hlt">Lamb</span> <span class="hlt">wave</span> ultrasound pitch-catch signals that are excited and sensed by piezoelectric wafer transducers bonded on a slender structure. Analytical models were established to simulate the longitudinal and flexural vibrations of the structures separately and parametric studies of the bonding layer properties, i.e. the shear transfer parameter, adhesive thickness, and shear modulus, were performed. The parametric studies indicate that there exists an optimal adhesive layer thickness that generates maximum ultrasound pitch-catch signal for both <span class="hlt">wave</span> modes. This prediction was subsequently validated by measurements. In addition, an improved match between the measured and simulated pitch-catch signals was achieved by adjusting the adhesive layer parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26233023','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26233023"><span id="translatedtitle">Experimental and numerical study of the excitability of zero group velocity <span class="hlt">Lamb</span> <span class="hlt">waves</span> by laser-ultrasound.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grünsteidl, Clemens M; Veres, István A; Murray, Todd W</p> <p>2015-07-01</p> <p>The excitability of zero group velocity (ZGV) <span class="hlt">Lamb</span> <span class="hlt">waves</span> using a pulsed laser source is investigated experimentally and through numerical simulation. Experimentally, a laser based ultrasonic technique is used to find the optical spot size on the sample surface that allows an optimal coupling of the optical energy into the ZGV mode. Numerical simulations, using the time domain finite differences technique, are carried out to model the thermoelastic generation process by laser irradiation and the propagation of the generated acoustic <span class="hlt">waves</span>. The experimental results are in good agreement with the numerical predictions. The experimentally and numerically obtained responses of the plate are investigated by a short-time Fourier transform. The responses show that the source diameter does not affect the fundamental behavior of the temporal decay of the ZGV mode. PMID:26233023</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27281285','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27281285"><span id="translatedtitle">Tunable <span class="hlt">Lamb</span> <span class="hlt">wave</span> band gaps in two-dimensional magnetoelastic phononic crystal slabs by an applied external magnetostatic field.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Changjiang; Sai, Yi; Chen, Jiujiu</p> <p>2016-09-01</p> <p>This paper theoretically investigates the band gaps of <span class="hlt">Lamb</span> mode <span class="hlt">waves</span> in two-dimensional magnetoelastic phononic crystal slabs by an applied external magnetostatic field. With the assumption of uniformly oriented magnetization, an equivalent piezomagnetic material model is used. The effects of magnetostatic field on phononic crystals are considered carefully in this model. The numerical results indicate that the width of the first band gap is significantly changed by applying the external magnetic field with different amplitude, and the ratio between the maximum and minimum gap widths reaches 228%. Further calculations demonstrate that the orientation of the magnetic field obviously affects the width and location of the first band gap. The contactless tunability of the proposed phononic crystal slabs shows many potential applications of vibration isolation in engineering. PMID:27281285</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AIPC.1511.1294B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AIPC.1511.1294B"><span id="translatedtitle">Air-coupled detection of the S1-ZGV <span class="hlt">lamb</span> mode in a concrete plate based on backward <span class="hlt">wave</span> propagation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bjurström, H.; Ryden, N.</p> <p>2013-01-01</p> <p>Impact Echo is commonly used to determine thickness of concrete plate like structures. The method is based on the generation and detection of the plate thickness resonance frequency, where the group velocity of the first higher symmetric <span class="hlt">Lamb</span> mode goes to zero (S1-ZGV). When using air-coupled microphones as receivers it is hard to determine the correct resonance frequency due to low signal to noise ratio. In this study multichannel signal processing is used to identify the S1-ZGV frequency, based on backward <span class="hlt">wave</span> propagation instead of the conventional amplitude spectrum approach. The original PDF file of this article, as supplied to AIP Publishing, contained some minor font problems within Figures 1, 4, 7, 8, and 9. An updated PDF file using the correct font within those figures was issued on June 3, 2013. There are no other changes to the scientific content.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22420180','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22420180"><span id="translatedtitle">Beam paths of flexural <span class="hlt">Lamb</span> <span class="hlt">waves</span> at high frequency in the first band within phononic crystal-based acoustic lenses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhao, J.; Boyko, O.; Bonello, B.</p> <p>2014-12-15</p> <p>This work deals with an analytical and numerical study of the focusing of the lowest order anti-symmetric <span class="hlt">Lamb</span> <span class="hlt">wave</span> in gradient index phononic crystals. Computing the ray trajectories of the elastic beam allowed us to analyze the lateral dimensions and shape of the focus, either in the inner or behind the phononic crystal-based acoustic lenses, for frequencies within a broad range in the first band. We analyzed and discussed the focusing behaviors inside the acoustic lenses where the focalization at sub-wavelength scale was achieved. The focalization behind the gradient index phononic crystal is shown to be efficient as well: we report on FMHM = 0.63λ at 11MHz.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001ChPhL..18.1620Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001ChPhL..18.1620Y&link_type=ABSTRACT"><span id="translatedtitle">A New Inverse Method of Elastic Constants for a Fibre-Reinforced Composite Plate from Laser-Based Ultrasonic <span class="hlt">Lamb</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Jing; Cheng, Jian-Chun</p> <p>2001-12-01</p> <p>A new inverse method based on the wavelet transform and artificial neural networks (ANN) is presented to recover elastic constants of a fibre-reinforced composite plate from laser-based ultrasonic <span class="hlt">Lamb</span> <span class="hlt">waves</span>. The transient waveforms obtained by numerical simulations under different elastic constants are taken as the input of the ANN for training and learning. The wavelet transform is employed for extracting the eigenvectors from the raw <span class="hlt">Lamb</span> <span class="hlt">wave</span> signals so as to simplify the structure of the ANN. Then these eigenvectors are input to a multi-layer internally recurrent neural network with a back-propagation algorithm. Finally, the experimental waveforms are used as the input in the whole system to inverse elastic constants of the experimental material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3574690','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3574690"><span id="translatedtitle"><span class="hlt">Lamb</span> <span class="hlt">Waves</span> Propagation along 3C-SiC/AlN Membranes for Application in Temperature-Compensated, High-Sensitivity Gravimetric Sensors</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Caliendo, Cinzia; D'Amico, Arnaldo; Castro, Fabio Lo</p> <p>2013-01-01</p> <p>The propagation of the fundamental quasi-symmetric <span class="hlt">Lamb</span> mode S0 travelling along 3C-SiC/c-AlN composite plates is theoretically studied with respect to the AlN and SiC film thickness, the acoustic <span class="hlt">wave</span> propagation direction and the electrical boundary conditions. The temperature effects on the phase velocity have been considered for four AlN/SiC-based electroacoustic coupling configurations, specifically addressing the design of temperature-compensated, enhanced-coupling, GHz-range electroacoustic devices. The gravimetric sensitivity and resolution of the four temperature-stable SiC/AlN composite structures are theoretically investigated with respect to both the AlN and SiC sensing surface. The SiC/AlN-based sensor performances are compared to those of surface acoustic <span class="hlt">waves</span> and <span class="hlt">Lamb</span> S0 mode mass sensors implemented on bulk conventional piezoelectric materials and on thin suspended membranes. PMID:23282585</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3472832','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3472832"><span id="translatedtitle">A Multi-Parameter Decoupling Method with a <span class="hlt">Lamb</span> <span class="hlt">Wave</span> Sensor for Improving the Selectivity of Label-Free Liquid Detection †</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhou, Lianqun; Wu, Yihui; Xuan, Ming; Manceau, Jean-François; Bastien, François</p> <p>2012-01-01</p> <p>In this paper, a liquid multi-parameter decoupling method with only one <span class="hlt">Lamb</span> <span class="hlt">wave</span> sensor is presented. In a <span class="hlt">Lamb</span> <span class="hlt">wave</span> sensor, antisymmetric modes (A01 mode for low frequency, A03 mode for high frequency) and symmetric modes (S0 mode) are used to detect multiple parameters of a liquid, such as its density, sound velocity, and viscosity. We found they can play very different roles in the detections. For example, the A01 mode is very sensitive to the liquid's density but the A03 mode is sensitive to the sound velocity. Here, the A0 mode is used to identify the density of the detected liquid and with this density value we obtained the viscosity by the amplitude shifts of the S0 mode. This could be a way to distinguish an unknown liquid with high sensitivity or to solve the problem of selectivity of label-free detection on biosensors. PMID:23112604</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19603867','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19603867"><span id="translatedtitle"><span class="hlt">Lamb</span> <span class="hlt">wave</span> characterization of corrosion-thinning in aircraft stringers: experiment and three-dimensional simulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bingham, Jill; Hinders, Mark</p> <p>2009-07-01</p> <p>The development of automatic guided <span class="hlt">wave</span> interpretation for detecting corrosion in aluminum aircraft structural stringers is described. The dynamic wavelet fingerprint technique (DWFT) is used to render the guided <span class="hlt">wave</span> mode information in two-dimensional binary images. Automatic algorithms then extract DWFT features that correspond to the distorted arrival times of the guided <span class="hlt">wave</span> modes of interest, which give insight into changes of the structure in the propagation path. To better understand how the guided <span class="hlt">wave</span> modes propagate through real structures, parallel-processing elastic <span class="hlt">wave</span> simulations using the finite integration technique (EFIT) has been performed. Three-dimensional (3D) simulations are used to examine models too complex for analytical solutions. They produce informative visualizations of the guided <span class="hlt">wave</span> modes in the structures and mimic the output from sensors placed in the simulation space. Using the previously developed mode extraction algorithms, the 3D EFIT results are compared directly to their experimental counterparts. PMID:19603867</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27144571','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27144571"><span id="translatedtitle">Multi-Mode Electromagnetic Ultrasonic <span class="hlt">Lamb</span> <span class="hlt">Wave</span> Tomography Imaging for Variable-Depth Defects in Metal Plates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Songling; Zhang, Yu; Wang, Shen; Zhao, Wei</p> <p>2016-01-01</p> <p>This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects in metal plates based on multi-mode electromagnetic ultrasonic <span class="hlt">Lamb</span> <span class="hlt">waves</span> (LWs). The dispersion characteristics determine that different modes of LWs are sensitive to different thicknesses of metal plates. In this work, the sensitivities to thickness variation of A0- and S0-mode LWs are theoretically studied. The principles and procedures for the cooperation of A0- and S0-mode LW CTI are proposed. Moreover, the experimental LW imaging system on an aluminum plate with a variable-depth defect is set up, based on A0- and S0-mode EMAT (electromagnetic acoustic transducer) arrays. For comparison, the traditional single-mode LW CTI method is used in the same experimental platform. The imaging results show that the computed thickness distribution by the proposed multi-mode method more accurately reflects the actual thickness variation of the defect, while neither the S0 nor the A0 single-mode method was able to distinguish thickness variation in the defect region. Moreover, the quantification of the defect's thickness variation is more accurate with the multi-mode method. Therefore, theoretical and practical results prove that the variable-depth defect in metal plates can be successfully quantified and visualized by the proposed multi-mode electromagnetic ultrasonic LW CTI method. PMID:27144571</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4883319','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4883319"><span id="translatedtitle">Multi-Mode Electromagnetic Ultrasonic <span class="hlt">Lamb</span> <span class="hlt">Wave</span> Tomography Imaging for Variable-Depth Defects in Metal Plates</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Huang, Songling; Zhang, Yu; Wang, Shen; Zhao, Wei</p> <p>2016-01-01</p> <p>This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects in metal plates based on multi-mode electromagnetic ultrasonic <span class="hlt">Lamb</span> <span class="hlt">waves</span> (LWs). The dispersion characteristics determine that different modes of LWs are sensitive to different thicknesses of metal plates. In this work, the sensitivities to thickness variation of A0- and S0-mode LWs are theoretically studied. The principles and procedures for the cooperation of A0- and S0-mode LW CTI are proposed. Moreover, the experimental LW imaging system on an aluminum plate with a variable-depth defect is set up, based on A0- and S0-mode EMAT (electromagnetic acoustic transducer) arrays. For comparison, the traditional single-mode LW CTI method is used in the same experimental platform. The imaging results show that the computed thickness distribution by the proposed multi-mode method more accurately reflects the actual thickness variation of the defect, while neither the S0 nor the A0 single-mode method was able to distinguish thickness variation in the defect region. Moreover, the quantification of the defect’s thickness variation is more accurate with the multi-mode method. Therefore, theoretical and practical results prove that the variable-depth defect in metal plates can be successfully quantified and visualized by the proposed multi-mode electromagnetic ultrasonic LW CTI method. PMID:27144571</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25468146','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25468146"><span id="translatedtitle">Numerical study and topology optimization of 1D periodic bimaterial phononic crystal plates for bandgaps of low order <span class="hlt">Lamb</span> <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hedayatrasa, Saeid; Abhary, Kazem; Uddin, Mohammad</p> <p>2015-03-01</p> <p>The optimum topology of bimaterial phononic crystal (PhCr) plates with one-dimensional (1D) periodicity to attain maximum relative bandgap width of low order <span class="hlt">Lamb</span> <span class="hlt">waves</span> is computationally investigated. The evolution of optimized topology with respect to filling fraction of constituents, alternatively stiff scattering inclusion, is explored. The underlying idea is to develop PhCr plate structures with high specific bandgap efficiency at particular filling fraction, or further with multiscale functionality through gradient of optimized PhCr unitcell all over the lattice array. Multiobjective genetic algorithm (GA) is employed in this research in conjunction with finite element method (FEM) for topology optimization of silicon-tungsten PhCr plate unitcells. A specialized FEM model is developed and verified for dispersion analysis of plate <span class="hlt">waves</span> and calculation of modal response. Modal band structure of regular PhCr plate unitcells with centric scattering layer is studied as a function of aspect ratio and filling fraction. Topology optimization is then carried out for a few aspect ratios, with and without prescribed symmetry, over various filling fractions. The efficiency of obtained solutions is verified as compared to corresponding regular centric PhCr plate unitcells. Moreover, being inspired by the obtained optimum topologies, definite and easy to produce topologies are proposed with enhanced bandgap efficiency as compared to centric unitcells. Finally a few cases are introduced to evaluate the frequency response of finite PhCr plate structures produced by achieved topologies and also to confirm the reliability of calculated modal band structures. Cases made by consecutive unitcells of different filling fraction are examined in order to attest the bandgap efficiency and multiscale functionality of such graded PhCr plate structures. PMID:25468146</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016SMaS...25h5035E&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016SMaS...25h5035E&link_type=ABSTRACT"><span id="translatedtitle">Damage localization in metallic plate structures using edge-reflected <span class="hlt">lamb</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ebrahimkhanlou, A.; Dubuc, B.; Salamone, S.</p> <p>2016-08-01</p> <p>This paper presents a model-based guided ultrasonic <span class="hlt">waves</span> imaging algorithm, in which multiple ultrasonic echoes caused by reflections from the plate’s boundaries are leveraged to enhance imaging performance. An analytical model is proposed to estimate the envelope of scattered <span class="hlt">waves</span>. Correlation between the estimated and experimental data is used to generate images. The proposed method is validated through experimental tests on an aluminum plate instrumented with three low profile piezoelectric transducers. Different damage conditions are simulated including through-thickness holes. Results are compared with two other imaging localization methods, that is, delay and sum and minimum variance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9431E..06A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9431E..06A"><span id="translatedtitle">Energy scavenging from <span class="hlt">acousto-elastic</span> metamaterial using local resonance phenomenon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ahmed, Riaz U.; Adiba, Afifa; Banerjee, Sourav</p> <p>2015-04-01</p> <p>This article presents the possibility of energy scavenging (ES) utilizing the physics of <span class="hlt">acousto-elastic</span> metamaterial (AEMM) and use them in a dual mode (Acoustic Filter and Energy Harvester), simultaneously. Concurrent <span class="hlt">wave</span> filtering and energy harvesting mechanism is previously presented using local resonance phenomenon in phononic crystal, however energy harvesting capabilities of AEMM is not reported extensively. Traditionally acoustic metamaterials are used in filtering acoustic <span class="hlt">waves</span> by trapping or guiding the acoustic energy, whereas this work presents that the trapped dynamic energy inside the soft constituent (matrix) of metamaterials can be significantly harvested by strategically embedding piezoelectric wafers in the matrix. With unit cell model, we asserted that at lower acoustic frequencies maximum power in the micro Watts (~36μW) range can be generated, which is significantly higher than the existing harvesters of same kind. Efficient energy scavengers at low acoustic frequencies are almost absent due to large required size relevant to the acoustic wavelength. In this work we propose sub <span class="hlt">wave</span> length scale energy scavengers utilizing the coupled physics of local, structural and matrix resonances. Upon validation of the argument through analytical, numerical and experimental studies, a broadband energy scavenger (ES) with multi-cell model is designed with varying geometrical properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SMaS...25d5023W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SMaS...25d5023W"><span id="translatedtitle">Analytical and numerical studies of approximate phase velocity matching based nonlinear S0 mode <span class="hlt">Lamb</span> <span class="hlt">waves</span> for the detection of evenly distributed microstructural changes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wan, X.; Tse, P. W.; Xu, G. H.; Tao, T. F.; Zhang, Q.</p> <p>2016-04-01</p> <p>Most previous studies on nonlinear <span class="hlt">Lamb</span> <span class="hlt">waves</span> are conducted using mode pairs that satisfying strict phase velocity matching and non-zero power flux criteria. However, there are some limitations in existence. First, strict phase velocity matching is not existed in the whole frequency bandwidth; Second, excited center frequency is not always exactly equal to the true phase-velocity-matching frequency; Third, mode pairs are isolated and quite limited in number; Fourth, exciting a single desired primary mode is extremely difficult in practice and the received signal is quite difficult to process and interpret. And few attention has been paid to solving these shortcomings. In this paper, nonlinear S0 mode <span class="hlt">Lamb</span> <span class="hlt">waves</span> at low-frequency range satisfying approximate phase velocity matching is proposed for the purpose of overcoming these limitations. In analytical studies, the secondary amplitudes with the propagation distance considering the fundamental frequency, the maximum cumulative propagation distance (MCPD) with the fundamental frequency and the maximum linear cumulative propagation distance (MLCPD) using linear regression analysis are investigated. Based on analytical results, approximate phase velocity matching is quantitatively characterized as the relative phase velocity deviation less than a threshold value of 1%. Numerical studies are also conducted using tone burst as the excitation signal. The influences of center frequency and frequency bandwidth on the secondary amplitudes and MCPD are investigated. S1-S2 mode with the fundamental frequency at 1.8 MHz, the primary S0 mode at the center frequencies of 100 and 200 kHz are used respectively to calculate the ratios of nonlinear parameter of Al 6061-T6 to Al 7075-T651. The close agreement of the computed ratios to the actual value verifies the effectiveness of nonlinear S0 mode <span class="hlt">Lamb</span> <span class="hlt">waves</span> satisfying approximate phase velocity matching for characterizing the material nonlinearity. Moreover, the ratios derived from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000AIPC..509.1049W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000AIPC..509.1049W"><span id="translatedtitle"><span class="hlt">Lamb</span> and SH <span class="hlt">wave</span> transducer arrays for the inspection of large areas of thick plates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilcox, P.; Lowe, M.; Cawley, P.</p> <p>2000-05-01</p> <p>The motivation for this work is to develop a rapid inspection system for large steel plates, such as those which the floors and walls of oil storage tanks are constructed from. One approach to inspecting plates using guided ultrasonic <span class="hlt">waves</span>, is to design a transduction system which uses monolithic devices such as wedge transducers, inter-digital transducers or meander coil electro-magnetic acoustic transducers (EMATs). Unfortunately, in order to achieve a given level of performance at a particular operating point on the dispersion curves, the physical dimensions of a monolithic transducer must be scaled in proportion to the thickness of plate under inspection. This renders the use of monolithic devices on thicker plates increasingly impractical for several reasons, not least because of the cost and difficulties involved in manufacturing large devices. Also, particular monolithic devices are limited to a small range of applications since they are generally designed to be sensitive to a particular wavelength and to be either unfocused or have a fixed focal length. A more attractive solution is to use an array device containing a number of elements which behave individually as point transducers. By controlling the elements individually, wavelength selection, beam steering and focusing can all be performed by post processing the same set of test data. Encouraging experimental results obtained using this technique will be shown for several array designs which operate on 5-10 mm thick plates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24582555','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24582555"><span id="translatedtitle">Corrosion and erosion monitoring in plates and pipes using constant group velocity <span class="hlt">Lamb</span> <span class="hlt">wave</span> inspection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nagy, Peter B; Simonetti, Francesco; Instanes, Geir</p> <p>2014-09-01</p> <p>Recent improvements in tomographic reconstruction techniques generated a renewed interest in short-range ultrasonic guided <span class="hlt">wave</span> inspection for real-time monitoring of internal corrosion and erosion in pipes and other plate-like structures. Emerging evidence suggests that in most cases the fundamental asymmetric A0 mode holds a distinct advantage over the earlier market leader fundamental symmetric S0 mode. Most existing A0 mode inspections operate at relatively low inspection frequencies where the mode is highly dispersive therefore very sensitive to variations in wall thickness. This paper examines the potential advantages of increasing the inspection frequency to the so-called constant group velocity (CGV) point where the group velocity remains essentially constant over a wide range of wall thickness variation, but the phase velocity is still dispersive enough to allow accurate wall thickness assessment from phase angle measurements. This paper shows that in the CGV region the crucial issue of temperature correction becomes especially simple, which is particularly beneficial when higher-order helical modes are also exploited for tomography. One disadvantage of working at such relatively high inspection frequency is that, as the slower A0 mode becomes faster and less dispersive, the competing faster S0 mode becomes slower and more dispersive. At higher inspection frequencies these modes cannot be separated any longer based on their vibration polarization only, which is mostly tangential for the S0 mode while mostly normal for the A0 at low frequencies, as the two modes become more similar as the frequency increases. Therefore, we propose a novel method for suppressing the unwanted S0 mode based on the Poisson effect of the material by optimizing the angle of inclination of the equivalent transduction force of the Electromagnetic Acoustic Transducers (EMATs) used for generation and detection purposes. PMID:24582555</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21485329','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21485329"><span id="translatedtitle">Monitoring trabecular bone microdamage using a dynamic <span class="hlt">acousto-elastic</span> testing method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moreschi, H; Callé, S; Guerard, S; Mitton, D; Renaud, G; Defontaine, M</p> <p>2011-03-01</p> <p>Dynamic <span class="hlt">acousto-elastic</span> testing (DAET) is based on the coupling of a low-frequency (LF) acoustic <span class="hlt">wave</span> and high-frequency ultrasound (US) pulses (probing <span class="hlt">wave</span>). It was developed to measure US viscoelastic and dissipative non-linearity in trabecular bone. It is well known that this complex biphasic medium contains microdamage, even when tissues are healthy. The purpose of the present study was to assess the sensitivity of DAET to monitor microdamage in human calcanei. Three protocols were therefore performed to investigate the regional heterogeneity of the calcaneus, the correlation between DAET measurements and microdamage revealed by histology, and DAET sensitivity to mechanically induced fatigue microdamage. The non-linear elastic parameter beta was computed for all these protocols. The study demonstrated the presence of high viscoelastic and dissipative non-linearity only in the region of the calcaneus close to the anterior talocalcaneal articulation (region of high bone density). Protocols 1 and 2 also showed that most unsorted calcanei did not naturally exhibit high non-linearity, which is correlated with a low level of microcracks. Nevertheless, when microdamage was actually present, high levels of US non-linearity were always found, with characteristic non-linear signatures such as hysteresis and tension/compression asymmetry. Finally, protocol 3 demonstrated the high sensitivity of DAET measurement to fatigue-induced microdamage. PMID:21485329</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012MS%26E...42a2026T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012MS%26E...42a2026T"><span id="translatedtitle">Measurement of nonlinear viscoelastic properties of fluids using Dynamic <span class="hlt">Acoustoelastic</span> Testing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trarieux, C.; Callé, S.; Poulin, A.; Tranchant, J.-F.; Moreschi, H.; Defontaine, M.</p> <p>2012-12-01</p> <p>A nonlinear ultrasound-based method called Dynamic <span class="hlt">Acoustoelastic</span> Testing (DAET) is used to assess nonlinear viscoelastic properties of fluids. This method is based on the interaction between two elastic <span class="hlt">waves</span>: a low-frequency (LF) sinusoidal <span class="hlt">wave</span> (4 kHz) to successively compress and expand the liquid as a bulk stress, and ultrasound (US) pulses (1 MHz) to simultaneously probe the sample at different states of the quasi-hydrostatic pressure. The DAET method provides estimations of the elastic nonlinearities issued from the Time Of Flight Modulations (TOFM) of the US pulses. The TOFM is plotted as a function of the LF acoustic pressure, allowing an estimation of the nonlinear elastic parameter B/A. In this study, we first present the results obtained in Newtonian fluids such as water and silicone oils. Simple viscoelastic gels (Carbomers and Xanthan gums) have also been tested exhibiting the same behavior: TOFM linearly related to LF pressure amplitude corresponding to classical quadratic nonlinearity. Finally, preliminary DAET measurements have been performed in biphasic systems composed of hard glass beads in a gel-based matrix and in gelatin during a gelation process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21218868','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21218868"><span id="translatedtitle">Dynamic <span class="hlt">acoustoelastic</span> testing of weakly pre-loaded unconsolidated water-saturated glass beads.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Renaud, Guillaume; Callé, Samuel; Defontaine, Marielle</p> <p>2010-12-01</p> <p>Dynamic <span class="hlt">acoustoelastic</span> testing is applied to weakly pre-loaded unconsolidated water-saturated glass beads. The gravitational acceleration produces, on the probed beads, a static stress of order 130 Pa, thus the granular medium is close to the jamming transition. A low-frequency (LF) acoustic <span class="hlt">wave</span> gently disturbs the medium, inducing successively slight expansion and compaction of the granular packing expected to modulate the number of contacts between beads. Ultrasound (US) pulses are emitted simultaneously to dynamically detect the induced modification of the granular skeleton. US propagation velocity and attenuation both increase when the LF pressure increases. The quadratic nonlinear elastic parameter β, related to the pressure dependence of US propagation velocity, was measured in the range 60-530 if water-saturated glass beads are considered as an effective medium. A dynamic modification of US scattering induced by beads is proposed to modulate US attenuation. Complex hysteretic behaviors and tension-compression asymmetry are also observed and analyzed by time-domain and spectral analyses. Furthermore acoustic nonlinearities are measured in cases of quasi-static and dynamic variations of the LF <span class="hlt">wave</span> amplitude, providing quantitatively similar acoustic nonlinearities but qualitatively different. PMID:21218868</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT........78Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT........78Y"><span id="translatedtitle">Guided <span class="hlt">Lamb</span> <span class="hlt">wave</span> based 2-D spiral phased array for structural health monitoring of thin panel structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoo, Byungseok</p> <p>2011-12-01</p> <p>In almost all industries of mechanical, aerospace, and civil engineering fields, structural health monitoring (SHM) technology is essentially required for providing the reliable information of structural integrity of safety-critical structures, which can help reduce the risk of unexpected and sometimes catastrophic failures, and also offer cost-effective inspection and maintenance of the structures. State of the art SHM research on structural damage diagnosis is focused on developing global and real-time technologies to identify the existence, location, extent, and type of damage. In order to detect and monitor the structural damage in plate-like structures, SHM technology based on guided <span class="hlt">Lamb</span> <span class="hlt">wave</span> (GLW) interrogation is becoming more attractive due to its potential benefits such as large inspection area coverage in short time, simple inspection mechanism, and sensitivity to small damage. However, the GLW method has a few critical issues such as dispersion nature, mode conversion and separation, and multiple-mode existence. Phased array technique widely used in all aspects of civil, military, science, and medical industry fields may be employed to resolve the drawbacks of the GLW method. The GLW-based phased array approach is able to effectively examine and analyze complicated structural vibration responses in thin plate structures. Because the phased sensor array operates as a spatial filter for the GLW signals, the array signal processing method can enhance a desired signal component at a specific direction while eliminating other signal components from other directions. This dissertation presents the development, the experimental validation, and the damage detection applications of an innovative signal processing algorithm based on two-dimensional (2-D) spiral phased array in conjunction with the GLW interrogation technique. It starts with general backgrounds of SHM and the associated technology including the GLW interrogation method. Then, it is focused on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JSMME...6..622T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JSMME...6..622T"><span id="translatedtitle">Dependence of Body <span class="hlt">Wave</span> Velocity on Borehole Stress Concentration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tian, Jiayong; Man, Yuanpeng; Qi, Hui</p> <p></p> <p>In order to develop ultrasonic method for the quantitative measurement of in-situ rock stresses, we investigate the influence of stress concentration on the body-<span class="hlt">wave</span> velocities around a borehole. First, the <span class="hlt">acoustoelasticity</span> theory of finite-deformation solids yields a direct and explicit quantitative borehole <span class="hlt">acoustoelasticity</span>, which reveals that the orientations of the maximum and minimum <span class="hlt">wave</span>-velocity shifts at the borehole surface coincide with the directions of the minimum and maximum far-field principal stresses, respectively. Second, pulse-echo measurement of <span class="hlt">wave</span>-velocity variations at the borehole surface in the sandstone sample under the biaxial compressional loadings is performed to validate the quantitative borehole <span class="hlt">acoustoelasticity</span>. The consistence of the experimental results with the theoretical prediction means that the ultrasonic method based on <span class="hlt">acoustoelasticity</span> theory could be a promising noncontact and non-destructive method for the quantitative measurement of in-situ rock stresses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27131699','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27131699"><span id="translatedtitle">Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor <span class="hlt">Lamb</span> <span class="hlt">wave</span> resonator with accurate two-port Y-parameter characterizations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Yong; Goh, Wang Ling; Chai, Kevin T-C; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu</p> <p>2016-04-01</p> <p>The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for <span class="hlt">Lamb</span> <span class="hlt">wave</span> resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in <span class="hlt">Lamb-wave</span> resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of <span class="hlt">Lamb-wave</span> resonators, providing accurate simulation to <span class="hlt">Lamb-wave</span> resonators and oscillators. PMID:27131699</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RScI...87d5004W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RScI...87d5004W"><span id="translatedtitle">Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor <span class="hlt">Lamb</span> <span class="hlt">wave</span> resonator with accurate two-port Y-parameter characterizations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Yong; Goh, Wang Ling; Chai, Kevin T.-C.; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu</p> <p>2016-04-01</p> <p>The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for <span class="hlt">Lamb</span> <span class="hlt">wave</span> resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in <span class="hlt">Lamb-wave</span> resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of <span class="hlt">Lamb-wave</span> resonators, providing accurate simulation to <span class="hlt">Lamb-wave</span> resonators and oscillators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1433..471P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1433..471P"><span id="translatedtitle">Stress dependent dispersion relations of acoustic <span class="hlt">waves</span> travelling on a chain of point masses connected by anharmonic linear and torsional springs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pluta, Mieczysław; Amjad, Umar; Klinghammer, Hermann; Jha, Diwaker; Tarar, Khurram; Grill, Wolfgang</p> <p>2012-05-01</p> <p>The propagation of a deformation along a flexural beam or plate depends on material properties, geometrical conditions like the beam cross-section, effects of stiffening or softening due to external stress, and last but not least the mode of the <span class="hlt">wave</span> including its polarization. The time-of-flight (TOF) of acoustic <span class="hlt">waves</span> is influenced by any of the above listed parameters. This effect is utilized in ultrasonic NDE and structural health monitoring applications. It was shown in earlier publications that the solutions of <span class="hlt">wave</span> equations for a linear chain model consisting of identical mass points, subject to a direction and distance dependent potential, show the dispersion properties and dependencies on externally applied stress of the lowest longitudinal and transversal plate modes. In the model presented here anharmonic potentials are introduced. The potentials are represented by torsional springs at each mass point and linear springs between them. Dynamic equations are derived, based on interactions with next and second next neighbors. The results obtained with the developed model are compared with experimental observations concerning the reaction of the TOF for the lowest <span class="hlt">Lamb</span> modes in an aluminum plate under variable in plane stress. The developed models are capable to demonstrate general aspects of the mode and frequency dependence of the <span class="hlt">acousto-elastic</span> coefficients for the lowest symmetric and antisymmetric <span class="hlt">Lamb</span> <span class="hlt">waves</span>. The introduced anharmonicities allow furthermore for a close approximation of the experimental findings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JAP...118v5305K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JAP...118v5305K&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Acoustoelastic</span> effect of textured (Ba,Sr)TiO3 thin films under an initial mechanical stress</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kamel, Marwa; Mseddi, Souhir; Njeh, Anouar; Donner, Wolfgang; Ben Ghozlen, Mohamed Hédi</p> <p>2015-12-01</p> <p><span class="hlt">Acoustoelastic</span> (AE) analysis of initial stresses plays an important role as a nondestructive tool in current engineering. Two textured BST (Ba0.65Sr0.35TiO3) thin films, with different substrate to target distance, were grown on Pt(111)/TiO2/SiO2/Si(001) substrate by rf-magnetron sputtering deposition techniques. A conventional "sin2 ψ" method to determine residual stress and strain in BST films by X-ray diffraction is applied. A laser acoustic <span class="hlt">waves</span> (LA-<span class="hlt">waves</span>) technique is used to generate surface acoustic <span class="hlt">waves</span> (SAW) propagating in both samples. Young's modulus E and Poisson ratio ν of BST films in different propagation directions are derived from the measured dispersion curves. Estimation of effective second-order elastic constants of BST thin films in stressed states is served in SAW study. This paper presents an original investigation of AE effect in prestressed Ba0.65Sr0.35TiO3 films, where the effective elastic constants and the effect of texture on second and third order elastic tensor are considered and used. The propagation behavior of Rayleigh and Love <span class="hlt">waves</span> in BST thin films under residual stress is explored and discussed. The guiding velocities affected by residual stresses, reveal some shifts which do not exceed four percent mainly in the low frequency range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22493037','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22493037"><span id="translatedtitle"><span class="hlt">Acoustoelastic</span> effect of textured (Ba,Sr)TiO{sub 3} thin films under an initial mechanical stress</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kamel, Marwa; Mseddi, Souhir; Njeh, Anouar; Ben Ghozlen, Mohamed Hédi; Donner, Wolfgang</p> <p>2015-12-14</p> <p><span class="hlt">Acoustoelastic</span> (AE) analysis of initial stresses plays an important role as a nondestructive tool in current engineering. Two textured BST (Ba{sub 0.65}Sr{sub 0.35}TiO{sub 3}) thin films, with different substrate to target distance, were grown on Pt(111)/TiO{sub 2}/SiO{sub 2}/Si(001) substrate by rf-magnetron sputtering deposition techniques. A conventional “sin{sup 2} ψ” method to determine residual stress and strain in BST films by X-ray diffraction is applied. A laser acoustic <span class="hlt">waves</span> (LA-<span class="hlt">waves</span>) technique is used to generate surface acoustic <span class="hlt">waves</span> (SAW) propagating in both samples. Young's modulus E and Poisson ratio ν of BST films in different propagation directions are derived from the measured dispersion curves. Estimation of effective second-order elastic constants of BST thin films in stressed states is served in SAW study. This paper presents an original investigation of AE effect in prestressed Ba{sub 0.65}Sr{sub 0.35}TiO{sub 3} films, where the effective elastic constants and the effect of texture on second and third order elastic tensor are considered and used. The propagation behavior of Rayleigh and Love <span class="hlt">waves</span> in BST thin films under residual stress is explored and discussed. The guiding velocities affected by residual stresses, reveal some shifts which do not exceed four percent mainly in the low frequency range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApPhL.109a3506W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApPhL.109a3506W&link_type=ABSTRACT"><span id="translatedtitle">GHz spurious mode free AlN <span class="hlt">lamb</span> <span class="hlt">wave</span> resonator with high figure of merit using one dimensional phononic crystal tethers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Guoqiang; Zhu, Yao; Merugu, Srinivas; Wang, Nan; Sun, Chengliang; Gu, Yuandong</p> <p>2016-07-01</p> <p>This letter reports a spurious mode free GHz aluminum nitride (AlN) <span class="hlt">lamb</span> <span class="hlt">wave</span> resonator (LWR) towards high figure of merit (FOM). One dimensional gourd-shape phononic crystal (PnC) tether with large phononic bandgaps is employed to reduce the acoustic energy dissipation into the substrate. The periodic PnC tethers are based on a 1 μm-thick AlN layer with 0.26 μm-thick Mo layer on top. A clean spectrum over a wide frequency range is obtained from the measurement, which indicates a wide-band suppression of spurious modes. Experimental results demonstrate that the fabricated AlN LWR has an insertion loss of 5.2 dB and a loaded quality factor (Q) of 1893 at 1.02 GHz measured in air. An impressive ratio of the resistance at parallel resonance (Rp) to the resistance at series resonance (Rs) of 49.8 dB is obtained, which is an indication of high FOM for LWR. The high Rp to Rs ratio is one of the most important parameters to design a radio frequency filter with steep roll-off.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9435E..2VF','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9435E..2VF"><span id="translatedtitle">Inductive wireless sensor-actuator node for structural health monitoring of fiber reinforced polymers by means of <span class="hlt">Lamb-waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Focke, Oliver; Salas, Mariugenia; Herrmann, Axel S.; Lang, Walter</p> <p>2015-03-01</p> <p>Wireless excitation of Piezo-Wafer-Active-Sensors (PWAS) was achieved using Low-frequency coils produced via Tailored-Fiber-Placement. Carbon Fiber Reinforced Polymer behaves as conductor and depending on the frequency it shields radio <span class="hlt">waves</span>; this effect is rising at high-frequency. A high permeability material was placed under the highfrequency antenna and re-tuning was performed to improve the quality of transmission. In this manner sensor responses were successfully transmitted wirelessly by analog amplitude modulation. The signals were evaluated to verify the functionality in presence of defects like delamination or holes. Generated power was confirmed to be enough to excite the actuator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMMR51A2151R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMMR51A2151R"><span id="translatedtitle">Dynamic Measures of Elastic Nonlinear (Anelastic) Behavior: Dynamic <span class="hlt">Acousto-Elasticity</span> Testing (DAET)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Renaud, G.; Le Bas, P.; Ten Cate, J. A.; Ulrich, T. J.; Carey, J. W.; Han, J.; Darling, T. W.; Johnson, P. A.</p> <p>2011-12-01</p> <p>Unraveling the physics of the earthquake source, reliable sequestration of CO2, predicting wellbore breakout in oil and gas reservoirs, monitoring thermal damage to rock in nuclear waste storage, and probing cement integrity require new approaches to material characterization and imaging. The elastic nonlinear material response is extremely promising in this regard. A persistent problem has been the direct relation between elastic nonlinearity and mechanical damage, because a reliable physics-based theory does not yet exist; however, recent work in medical nonlinear acoustics has led to an experimental breakthrough in measuring material nonlinear response. The breakthrough, termed Dynamic <span class="hlt">Acousto-Elasticity</span> Testing (e.g., Renaud et al, 2008), has significant implication to development of a physics based theory, and thus ultimately to our ability to directly relate nonlinear material behavior to damage. The method provides the means to dynamically study the velocity-pressure and attenuation-pressure behaviors through the full <span class="hlt">wave</span> cycle in contrast to most methods that measure average response (e.g., Nonlinear Resonance Ultrasound Spectroscopy [e.g., Guyer and Johnson, 2009]). The method relies on exciting a sample with a low frequency vibration in order to cycle it through stress-strain multiple times. Simultaneously, a high frequency ultrasonic source applies pulses and the change in wavespeed as a function of the low frequency stress is measured. In crystalline rock, we expect that the elastic nonlinearity arises from the microcracks and dislocations contained within individual crystals. In contrast, sandstones, limestones and other sedimentary rocks may have other origin(s) of elastic nonlinearity that are currently under debate. Thus we can use a crystalline sample as a point of reference from which to extrapolate to other sources of nonlinear mechanisms. We report results from our preliminary studies applying a number of room-dry rock samples of differing rock</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009pfap.conf....6B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009pfap.conf....6B&link_type=ABSTRACT"><span id="translatedtitle">Willis E. <span class="hlt">Lamb</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berman, Paul</p> <p>2009-03-01</p> <p>The atomic and optical physics community lost one of its pioneers with the death of Willis E. <span class="hlt">Lamb</span>, Jr. on May 15, 2008. <span class="hlt">Lamb</span> was born on July 12, 1913, received the BS degree in Chemistry at Berkeley in 1934, and obtained his PhD under the tutelage of J. Robert Oppenheimer at Berkeley in 1938. He served on the faculties of Columbia University, Stanford University, Oxford University, Yale University, and the University of Arizona. <span class="hlt">Lamb</span> received the Nobel prize in 1955 for his work on the fine structure of hydrogen and was awarded the President's National Medal for Science in 2000...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR13A2246R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR13A2246R"><span id="translatedtitle">On the influence of strain rate in <span class="hlt">acousto-elasticity</span> : experimental results for Berea sandstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riviere, J. V.; Candela, T.; Scuderi, M.; Marone, C.; Guyer, R. A.; Johnson, P. A.</p> <p>2013-12-01</p> <p>Elastic nonlinear effects are pervasive in the Earth, including during strong ground motion, tidal forcing and earthquake slip processes. We study elastic nonlinear effects in the laboratory with the goal of developing new methods to probe elastic changes in the Earth, and to characterize and understand their origins. Here we report on nonlinear, frequency dispersion effects by applying a method termed dynamic <span class="hlt">acousto-elasticity</span> (DAE), analogous to quasi-static <span class="hlt">acousto-elasticity</span>. DAE allows one to obtain the elastic behavior over the entire dynamic cycle, detailing the full nonlinear behavior under tension and compression, including hysteresis and memory effects. We perform DAE on samples of Berea sandstone subject to 0.5 MPa uniaxial and biaxial loading conditions with oscillating loads at frequencies from 0.001 to 10 Hz and amplitudes of a few 100 kPa. We compare results to DAE measurements made in the kHz range. We observe that the average decrease in modulus due to nonlinear material softening increases with frequency, suggesting a frequency and/or a strain rate dependence. Previous quasi-static measurements (Claytor et al., GRL 2009) show that stress-strain nonlinear hysteretic behavior disappears when the experiment is performed at a very low strain-rate, implying that a rate dependent nonlinear elastic model would be useful (Gusev et al., PRB 2004). Our results also suggest that when elastic nonlinear Earth processes are studied, stress forcing frequency is an important consideration, and may lead to unexpected behaviors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMMR23B4346R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMMR23B4346R"><span id="translatedtitle">Dynamic <span class="hlt">Acousto-Elasticity</span>: Pressure and Frequency Dependences in Berea Sandstone.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riviere, J. V.; Pimienta, L.; Latour, S.; Fortin, J.; Schubnel, A.; Johnson, P. A.</p> <p>2014-12-01</p> <p>Nonlinear elasticity is studied at the laboratory scale with the goal of understanding observations at earth scales, for instance during strong ground motion, tidal forcing and earthquake slip processes. Here we report frequency and pressure dependences on elasticity when applying dynamic <span class="hlt">acousto-elasticity</span> (DAE) of rock samples, analogous to quasi-static <span class="hlt">acousto-elasticity</span>. DAE allows one to obtain the elastic behavior over the entire dynamic cycle, detailing the full nonlinear behavior under tension and compression, including hysteresis and memory effects. We perform DAE on a sample of Berea sandstone subject to 0.5MPa uniaxial load, with sinusoidal oscillating strain amplitudes ranging from 10-6 to 10-5 and at frequencies from 0.1 to 260Hz. In addition, the confining pressure is increased stepwise from 0 to 30MPa. We compare results to previous measurements made at lower (mHz) and higher (kHz) frequencies. Nonlinear elastic parameters corresponding to conditioning effects, third order elastic constants and fourth order elastic constants are quantitatively compared over the pressure and frequency ranges. We observe that the decrease in modulus due to conditioning increases with frequency, suggesting a frequency and/or strain-rate dependence that should be included in nonlinear elastic models of rocks. In agreement with previous measurements, nonlinear elastic effects also decrease with confining pressure, suggesting that nonlinear elastic sources such as micro-cracks, soft bonds and dislocations are turned off as the pressure increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol10/pdf/CFR-2010-title7-vol10-sec1280-112.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol10/pdf/CFR-2010-title7-vol10-sec1280-112.pdf"><span id="translatedtitle">7 CFR 1280.112 - <span class="hlt">Lamb</span> products.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 7 Agriculture 10 2010-01-01 2010-01-01 false <span class="hlt">Lamb</span> products. 1280.112 Section 1280.112 Agriculture... INFORMATION ORDER <span class="hlt">Lamb</span> Promotion, Research, and Information Order Definitions § 1280.112 <span class="hlt">Lamb</span> products. <span class="hlt">Lamb</span> products means products produced in whole or in part from <span class="hlt">lamb</span>, including pelts, and excluding wool...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol10/pdf/CFR-2010-title7-vol10-sec1280-111.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol10/pdf/CFR-2010-title7-vol10-sec1280-111.pdf"><span id="translatedtitle">7 CFR 1280.111 - <span class="hlt">Lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... INFORMATION ORDER <span class="hlt">Lamb</span> Promotion, Research, and Information Order Definitions § 1280.111 <span class="hlt">Lamb</span>. <span class="hlt">Lamb</span> means ovine animals of any age, including ewes and rams. ... Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26527393','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26527393"><span id="translatedtitle">Inverse characterization of plates using zero group velocity <span class="hlt">Lamb</span> modes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grünsteidl, Clemens; Murray, Todd W; Berer, Thomas; Veres, István A</p> <p>2016-02-01</p> <p>In the presented work, the characterization of plates using zero group velocity <span class="hlt">Lamb</span> modes is discussed. First, analytical expressions are shown for the determination of the k-ω location of the zero group velocity <span class="hlt">Lamb</span> modes as a function of the Poisson's ratio. The analytical expressions are solved numerically and an inverse problem is formulated to determine the unknown <span class="hlt">wave</span> velocities in plates of known thickness. The analysis is applied to determine the elastic properties of tungsten and aluminum plates based on the experimentally measured frequency spectra. PMID:26527393</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26264450','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26264450"><span id="translatedtitle">Risk factors associated with <span class="hlt">lambing</span> traits.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McHugh, N; Berry, D P; Pabiou, T</p> <p>2016-01-01</p> <p>The objective of this study was to establish the risk factors associated with both <span class="hlt">lambing</span> difficulty and <span class="hlt">lamb</span> mortality in the Irish sheep multibreed population. A total of 135 470 <span class="hlt">lambing</span> events from 42 675 ewes in 839 Irish crossbred and purebred flocks were available. Risk factors associated with producer-scored ewe <span class="hlt">lambing</span> difficulty score (scale of one (no difficulty) to four (severe difficulty)) were determined using linear mixed models. Risk factors associated with the logit of the probability of <span class="hlt">lamb</span> mortality at birth (i.e. binary trait) were determined using generalised estimating equations. For each dependent variable, a series of simple regression models were developed as well as a multiple regression model. In the simple regression models, greater <span class="hlt">lambing</span> difficulty was associated with quadruplet bearing, younger ewes, of terminal breed origin, <span class="hlt">lambing</span> in February; for example, first parity ewes experienced greater (P7.0 kg) birth weights, quadruplet born <span class="hlt">lambs</span> and <span class="hlt">lambs</span> that experienced a more difficult <span class="hlt">lambing</span> (predicted probability of death for <span class="hlt">lambs</span> that required severe and veterinary assistance of 0.15 and 0.32, respectively); <span class="hlt">lambs</span> from dual-purpose breeds and born to younger ewes were also at greater risk of mortality. In the multiple regression model, the association between ewe parity, age at first <span class="hlt">lambing</span>, year of <span class="hlt">lambing</span> and <span class="hlt">lamb</span> mortality no longer persisted. The trend in solutions of the levels of each fixed effect that remained associated with <span class="hlt">lamb</span> mortality in the multiple regression model, did not differ from the trends observed in the simple regression models although the differential in relative risk between the different <span class="hlt">lambing</span> difficulty scores was greater in the multiple regression model. Results from this study show that many common flock- and animal-level factors are associated with both <span class="hlt">lambing</span> difficulty and <span class="hlt">lamb</span> mortality and management of different risk category groups (e.g. scanned litter sizes, ewe age groups) can be used</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830058582&hterms=ejecta+explosive&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dejecta%2Bexplosive','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830058582&hterms=ejecta+explosive&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dejecta%2Bexplosive"><span id="translatedtitle"><span class="hlt">Lamb</span> pulse observed in nature</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kanamori, H.; Given, J. W.</p> <p>1983-01-01</p> <p>It is shown that seismograms observed at Longmire, Washington, for four eruptions of Mt. St. Helens, those on May 18, June 13, August 7, and August 8, 1980, can be interpreted as <span class="hlt">Lamb</span> pulses excited by a nearly vertical single force representing the counter force of the eruption. These data furnish reliable estimates of the impulse of the force K (time integral of the force), from which the total momentum and the kinetic energy, E, of the ejecta associated with the eruption can be estimated. The estimates made of K are 1.4 x 10 to the 19th, 1.4 x 10 to the 16th, 3.7 x 10 to the 15th, and 2.8 x 10 to the 15th dynes-sec for the four eruptions (given chronologically). The corresponding estimates for E range from 0.70 to 2.6 x 10 to the 23rd, 0.70 to 2.6 x 10 to the 20th, 1.9 x 10 to the 19th, and 1.4 to 5.3 x 10 to the 19th erg using values of ejecta velocity ranging from 100 to 375 m/sec. The ratio of K to the amplitude of the air <span class="hlt">wave</span> excited by the eruption is found to be 20 to 40 times larger for the main event on May 18 than for the other events, indicating a significant difference in the eruptive mechanism. A digital seismograph in the vicinity of a volcano is shown to provide a simple means for quantifying the explosive power of a volcanic eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol10/pdf/CFR-2011-title7-vol10-sec1280-112.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol10/pdf/CFR-2011-title7-vol10-sec1280-112.pdf"><span id="translatedtitle">7 CFR 1280.112 - <span class="hlt">Lamb</span> products.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 7 Agriculture 10 2011-01-01 2011-01-01 false <span class="hlt">Lamb</span> products. 1280.112 Section 1280.112 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE <span class="hlt">LAMB</span> PROMOTION, RESEARCH, AND INFORMATION ORDER <span class="hlt">Lamb</span> Promotion,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=137969','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=137969"><span id="translatedtitle">ANALYSIS OF <span class="hlt">LAMB</span> MORTALITY USING COMPETING RISKS</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>A competing risks model was used to describe <span class="hlt">lamb</span> mortality up to four weeks of age in a composite sheep flock with 8,642 <span class="hlt">lamb</span> records. Discrete survival methods were applied using sire and animal models. The results indicated that substantial variation exists in the risk of <span class="hlt">lambs</span> dying from diffe...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol10/pdf/CFR-2011-title7-vol10-sec1280-217.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol10/pdf/CFR-2011-title7-vol10-sec1280-217.pdf"><span id="translatedtitle">7 CFR 1280.217 - <span class="hlt">Lamb</span> purchases.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 7 Agriculture 10 2011-01-01 2011-01-01 false <span class="hlt">Lamb</span> purchases. 1280.217 Section 1280.217 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE <span class="hlt">LAMB</span> PROMOTION, RESEARCH, AND INFORMATION ORDER <span class="hlt">Lamb</span> Promotion,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol10/pdf/CFR-2010-title7-vol10-sec1280-217.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol10/pdf/CFR-2010-title7-vol10-sec1280-217.pdf"><span id="translatedtitle">7 CFR 1280.217 - <span class="hlt">Lamb</span> purchases.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 7 Agriculture 10 2010-01-01 2010-01-01 false <span class="hlt">Lamb</span> purchases. 1280.217 Section 1280.217 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE <span class="hlt">LAMB</span> PROMOTION, RESEARCH, AND INFORMATION ORDER <span class="hlt">Lamb</span> Promotion,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol10/pdf/CFR-2012-title7-vol10-sec1280-217.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol10/pdf/CFR-2012-title7-vol10-sec1280-217.pdf"><span id="translatedtitle">7 CFR 1280.217 - <span class="hlt">Lamb</span> purchases.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 7 Agriculture 10 2012-01-01 2012-01-01 false <span class="hlt">Lamb</span> purchases. 1280.217 Section 1280.217 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE <span class="hlt">LAMB</span> PROMOTION, RESEARCH, AND INFORMATION ORDER <span class="hlt">Lamb</span> Promotion,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3962655','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3962655"><span id="translatedtitle">Feasibility and repeatability for in vivo measurements of stiffness gradients in the canine gastrocnemius tendon using an <span class="hlt">acoustoelastic</span> strain gauge</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ellison, Michelle; Kobayashi, Hirohito; Delaney, Fern; Danielson, Kelson; Vanderby, Ray; Muir, Peter; Forrest, Lisa J</p> <p>2014-01-01</p> <p>B-mode ultrasound is an established imaging modality for evaluating canine tendon injury. However, full extent of tendon injury often remains difficult to estimate, as small changes in sonographic appearance are associated with large changes in biomechanical strength. The <span class="hlt">acoustoelastic</span> strain gauge (ASG) is an ultrasound-based tissue evaluation technique that relates the change in echo intensity observed during relaxation or stretching of tendons to the tissue’s mechanical properties. This technique deduces stiffness gradient (the rate of change of normalized stiffness as a function of tissue strain) by analyzing the ultrasound dynamic images captured from gradually deforming tissue. <span class="hlt">Acoustoelastic</span> strain gauge has been proven to accurately model strain and stiffness within tendons in vitro. To determine the feasibility and repeatability for in vivo ASG measurements of canine tendon function, stiffness gradients for the gastrocnemius tendons of ten clinically normal dogs were recorded by two non-independent observers at three sites (musculotendinous junction, mid tendon, and insertion). Average stiffness gradient indices (0.0132, 0.0141, 0.0136) and dispersion values (0.0053, 0.0054, 0.0057) for each site, respectively, were consistent with published mechanical properties for normal canine tendon. Mean differences of the average stiffness gradient index and dispersion value between observers and between limbs for each site were less than 16%. Using interclass coefficients (ICC), intraobserver (ICC 0.79–0.98) and interobserver (ICC 0.77–0.95) reproducibility was good to excellent. Right and left limb values were symmetric (ICC 0.74–0.92). Findings from this study indicated that ASG is a feasible and repeatable technique for measuring stiffness gradients in canine tendons. PMID:23663072</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=307567','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=307567"><span id="translatedtitle">Sarcocystosis in a stillborn <span class="hlt">lamb</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Confirmed congenital sarcocystosis has not been reported in sheep and extremely rarely in other domestic ruminants. Sarcocystosis was diagnosed in a stillborn <span class="hlt">lamb</span> with microscopic lesions predominantly in the central nervous system and placenta. Encephalitis was characterized by multiple foci of gl...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21989878','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21989878"><span id="translatedtitle">Phononic plate <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Tsung-Tsong; Hsu, Jin-Chen; Sun, Jia-Hong</p> <p>2011-10-01</p> <p>In the past two decades, phononic crystals (PCs) which consist of periodically arranged media have attracted considerable interest because of the existence of complete frequency band gaps and maneuverable band structures. Recently, <span class="hlt">Lamb</span> <span class="hlt">waves</span> in thin plates with PC structures have started to receive increasing attention for their potential applications in filters, resonators, and waveguides. This paper presents a review of recent works related to phononic plate <span class="hlt">waves</span> which have recently been published by the authors and coworkers. Theoretical and experimental studies of <span class="hlt">Lamb</span> <span class="hlt">waves</span> in 2-D PC plate structures are covered. On the theoretical side, analyses of <span class="hlt">Lamb</span> <span class="hlt">waves</span> in 2-D PC plates using the plane <span class="hlt">wave</span> expansion (PWE) method, finite-difference time-domain (FDTD) method, and finite-element (FE) method are addressed. These methods were applied to study the complete band gaps of <span class="hlt">Lamb</span> <span class="hlt">waves</span>, characteristics of the propagating and localized <span class="hlt">wave</span> modes, and behavior of anomalous refraction, called negative refraction, in the PC plates. The theoretical analyses demonstrated the effects of PC-based negative refraction, lens, waveguides, and resonant cavities. We also discuss the influences of geometrical parameters on the guiding and resonance efficiency and on the frequencies of waveguide and cavity modes. On the experimental side, the design and fabrication of a silicon-based <span class="hlt">Lamb</span> <span class="hlt">wave</span> resonator which utilizes PC plates as reflective gratings to form the resonant cavity are discussed. The measured results showed significant improvement of the insertion losses and quality factors of the resonators when the PCs were applied. PMID:21989878</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...620599R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...620599R"><span id="translatedtitle">Purcell effect and <span class="hlt">Lamb</span> shift as interference phenomena</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rybin, Mikhail V.; Mingaleev, Sergei F.; Limonov, Mikhail F.; Kivshar, Yuri S.</p> <p>2016-02-01</p> <p>The Purcell effect and <span class="hlt">Lamb</span> shift are two well-known physical phenomena which are usually discussed in the context of quantum electrodynamics, with the zero-point vibrations as a driving force of those effects in the quantum approach. Here we discuss the classical counterparts of these quantum effects in photonics, and explain their physics trough interference <span class="hlt">wave</span> phenomena. As an example, we consider a waveguide in a planar photonic crystal with a side-coupled defect, and demonstrate a perfect agreement between the results obtained on the basis of quantum and classic approaches and reveal their link to the Fano resonance. We find that in such a waveguide-cavity geometry the Purcell effect can modify the lifetime by at least 25 times, and the <span class="hlt">Lamb</span> shift can exceed 3 half-widths of the cavity spectral line.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26860195','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26860195"><span id="translatedtitle">Purcell effect and <span class="hlt">Lamb</span> shift as interference phenomena.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rybin, Mikhail V; Mingaleev, Sergei F; Limonov, Mikhail F; Kivshar, Yuri S</p> <p>2016-01-01</p> <p>The Purcell effect and <span class="hlt">Lamb</span> shift are two well-known physical phenomena which are usually discussed in the context of quantum electrodynamics, with the zero-point vibrations as a driving force of those effects in the quantum approach. Here we discuss the classical counterparts of these quantum effects in photonics, and explain their physics trough interference <span class="hlt">wave</span> phenomena. As an example, we consider a waveguide in a planar photonic crystal with a side-coupled defect, and demonstrate a perfect agreement between the results obtained on the basis of quantum and classic approaches and reveal their link to the Fano resonance. We find that in such a waveguide-cavity geometry the Purcell effect can modify the lifetime by at least 25 times, and the <span class="hlt">Lamb</span> shift can exceed 3 half-widths of the cavity spectral line. PMID:26860195</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4748299','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4748299"><span id="translatedtitle">Purcell effect and <span class="hlt">Lamb</span> shift as interference phenomena</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rybin, Mikhail V.; Mingaleev, Sergei F.; Limonov, Mikhail F.; Kivshar, Yuri S.</p> <p>2016-01-01</p> <p>The Purcell effect and <span class="hlt">Lamb</span> shift are two well-known physical phenomena which are usually discussed in the context of quantum electrodynamics, with the zero-point vibrations as a driving force of those effects in the quantum approach. Here we discuss the classical counterparts of these quantum effects in photonics, and explain their physics trough interference <span class="hlt">wave</span> phenomena. As an example, we consider a waveguide in a planar photonic crystal with a side-coupled defect, and demonstrate a perfect agreement between the results obtained on the basis of quantum and classic approaches and reveal their link to the Fano resonance. We find that in such a waveguide-cavity geometry the Purcell effect can modify the lifetime by at least 25 times, and the <span class="hlt">Lamb</span> shift can exceed 3 half-widths of the cavity spectral line. PMID:26860195</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec59-303.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec59-303.pdf"><span id="translatedtitle">7 CFR 59.303 - Mandatory reporting of <span class="hlt">lamb</span> carcasses and boxed <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... characteristics of each transaction: (i) The type of transaction; (ii) The USDA quality grade of <span class="hlt">lamb</span>; (iii) The USDA yield grade; (iv) The estimated weight range of the carcasses; and (v) The product delivery period... characteristics, if applicable; (iii) The USDA quality grade of <span class="hlt">lamb</span>; (iv) The cut of <span class="hlt">lamb</span>, referencing the...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec59-303.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec59-303.pdf"><span id="translatedtitle">7 CFR 59.303 - Mandatory reporting of <span class="hlt">lamb</span> carcasses and boxed <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... characteristics of each transaction: (i) The type of transaction; (ii) The USDA quality grade of <span class="hlt">lamb</span>; (iii) The USDA yield grade; (iv) The estimated weight range of the carcasses; and (v) The product delivery period... characteristics, if applicable; (iii) The USDA quality grade of <span class="hlt">lamb</span>; (iv) The cut of <span class="hlt">lamb</span>, referencing the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22280673','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22280673"><span id="translatedtitle"><span class="hlt">Lamb</span> shift in muonic deuterium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorchtein, Mikhail; Vanderhaeghen, Marc; Carlson, Carl E.</p> <p>2013-11-07</p> <p>We consider the two-photon exchange contribution to the 2P-2S <span class="hlt">Lamb</span> shift in muonic deuterium in the framework of forward dispersion relations. The dispersion integrals are evaluated with minimal model dependence using experimental data on elastic deuteron form factors and inelastic electron-deuteron scattering, both in the quasielastic and hadronic range. The subtraction constant that is required to ensure convergence of the dispersion relation for the forward Compton amplitude T{sub 1} (ν,Q{sup 2}) is related to the deuteron magnetic polarizability β(Q{sup 2}) and represents the main source of uncertainty in our analysis. We obtain for the <span class="hlt">Lamb</span> shift ΔE{sub 2P-2S} = 1.620±0.190 meV and discuss ways to further reduce this uncertainty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70045395','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70045395"><span id="translatedtitle">Techniques for capturing bighorn sheep <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Smith, Joshua B.; Walsh, Daniel P.; Goldstein, Elise J.; Parsons, Zachary D.; Karsch, Rebekah C.; Stiver, Julie R.; Cain, James W.; Raedeke, Kenneth J.; Jenks, Jonathan A.</p> <p>2014-01-01</p> <p>Low <span class="hlt">lamb</span> recruitment is a major challenge facing managers attempting to mitigate the decline of bighorn sheep (Ovis canadensis), and investigations into the underlying mechanisms are limited because of the inability to readily capture and monitor bighorn sheep <span class="hlt">lambs</span>. We evaluated 4 capture techniques for bighorn sheep <span class="hlt">lambs</span>: 1) hand-capture of <span class="hlt">lambs</span> from radiocollared adult females fitted with vaginal implant transmitters (VITs), 2) hand-capture of <span class="hlt">lambs</span> of intensively monitored radiocollared adult females, 3) helicopter net-gunning, and 4) hand-capture of <span class="hlt">lambs</span> from helicopters. During 2010–2012, we successfully captured 90% of <span class="hlt">lambs</span> from females that retained VITs to ≤1 day of parturition, although we noted differences in capture rates between an area of high road density in the Black Hills (92–100%) of South Dakota, USA, and less accessible areas of New Mexico (71%), USA. Retention of VITs was 78% with pre-partum expulsion the main cause of failure. We were less likely to capture <span class="hlt">lambs</span> from females that expelled VITs ≥1 day of parturition (range = 80–83%) or females that were collared without VITs (range = 60–78%). We used helicopter net-gunning at several sites in 1999, 2001–2002, and 2011, and it proved a useful technique; however, at one site, attempts to capture <span class="hlt">lambs</span> led to <span class="hlt">lamb</span> predation by golden eagles (Aquila chrysaetos). We attempted helicopter hand-captures at one site in 1999, and they also were successful in certain circumstances and avoided risk of physical trauma from net-gunning; however, application was limited. In areas of low accessibility or if personnel lack the ability to monitor females and/or VITs for extended periods, helicopter capture may provide a viable option for <span class="hlt">lamb</span> capture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhPro..70..594X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhPro..70..594X"><span id="translatedtitle">Nondestructive Testing Residual Stress Using Ultrasonic Critical Refracted Longitudinal <span class="hlt">Wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Chunguang; Song, Wentao; Pan, Qinxue; Li, Huanxin; Liu, Shuai</p> <p></p> <p>Residual stress has significant impacts on the performance of the mechanical components, especially on its strength, fatigue life and corrosion resistance and dimensional stability. Based on theory of <span class="hlt">acoustoelasticity</span>, the testing principle of ultrasonic LCR <span class="hlt">wave</span> method is analyzed. The testing system of residual stress is build. The method of calibration of stress coefficient is proposed in order to improve the detection precision. At last, through experiments and applications on residual stress testing of oil pipeline weld joint, vehicle's torsion shaft, glass and ceramics, gear tooth root, and so on, the result show that it deserved to be studied deeply on application and popularization of ultrasonic LCR <span class="hlt">wave</span> method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=hydrogen+AND+energy&pg=7&id=EJ239391','ERIC'); return false;" href="http://eric.ed.gov/?q=hydrogen+AND+energy&pg=7&id=EJ239391"><span id="translatedtitle"><span class="hlt">Lamb</span> Shift in Nonrelativistic Quantum Electrodynamics.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Grotch, Howard</p> <p>1981-01-01</p> <p>The bound electron self-energy or <span class="hlt">Lamb</span> shift is calculated in nonrelativistic quantum electrodynamics. Retardation is retained and also an interaction previously dropped in other nonrelativistic approaches is kept. Results are finite without introducing a cutoff and lead to a <span class="hlt">Lamb</span> shift in hydrogen of 1030.9 MHz. (Author/JN)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1319983','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1319983"><span id="translatedtitle">Swayback (Enzootic Ataxia) in Alberta <span class="hlt">Lambs</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chalmers, G. A.</p> <p>1974-01-01</p> <p>Swayback (enzootic ataxia), a disease not previously described in Canada, occurred in newborn <span class="hlt">lambs</span> in Alberta in 1972. Of 100 <span class="hlt">lambs</span> born in one flock, over 60 succumbed in the enzootic. The diagnosis was based on the presence of a) gross cavitations and gelatinous lesions of the cerebral white matter in 16 of 24 (66.67%) <span class="hlt">lambs</span> examined, b) central chromatolysis and hyalinization of neurons of the red and vestibular nuclei and reticular formation and of the lateral and ventral horns of the spinal cord, c) myelin deficiencies of the dorsolateral and sulcomarginal funiculi of the spinal cord and d) low hepatic and serum copper levels in affected <span class="hlt">lambs</span> and low serum copper levels in the ewes. The feeding of sugar beet-(beta saccharifera) top silage to the ewes during pregnancy, <span class="hlt">lambing</span> and lactation, and its relationship to the enzootic is discussed. ImagesFig. 1.Fig. 2.Fig. 3.Fig. 4. PMID:4274817</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18804832','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18804832"><span id="translatedtitle">Guided ultrasonic <span class="hlt">waves</span> for non-destructive monitoring of the stress levels in prestressed steel strands.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chaki, S; Bourse, G</p> <p>2009-02-01</p> <p>The safety of prestressed civil structures such as bridges, dams, nuclear power plants, etc. directly involves the security of both environment and users. Health monitoring of the tensioning components, such as strands, tendons, bars, anchorage bolts, etc. is an important research topic and a challenging task bringing together the non-destructive evaluation (NDE) and civil engineering communities. This paper deals with a guided ultrasonic <span class="hlt">wave</span> procedure for monitoring the stress levels in seven-wire steel strands (15.7 mm in diameter). The mechanical and geometrical characteristics of the prestressed strands were taken into account for optimizing the measurement configuration and then the choice of the guided ultrasonic mode at a suitable frequency. Simplified <span class="hlt">acoustoelastic</span> formulations were derived from the <span class="hlt">acoustoelasticity</span> theory according to either calibration test or in situ measurement. The results from <span class="hlt">acoustoelastic</span> measurements on the seven-wire steel strands are presented and discussed in the case of calibration tests and industrially prestressed strands. They show the potential and the suitability of the proposed guided <span class="hlt">wave</span> method for evaluating the stress levels in the tested seven-wire steel strands. PMID:18804832</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/2507622','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/2507622"><span id="translatedtitle">Meclofenamate increases ventilation in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guerra, F A; Savich, R D; Clyman, R I; Kitterman, J A</p> <p>1989-01-01</p> <p>To investigate the effects of the prostaglandin synthetase inhibitor, meclofenamate, on postnatal ventilation, we studied 11 unanaesthetised, spontaneously-breathing <span class="hlt">lambs</span> at an average age of 7.9 +/- 1.1 days (SEM; range 5-14 days) and an average weight of 4.9 +/- 0.5 kg (range 3.0-7.0 kg). After a 30-min control period we infused 4.23 mg/kg meclofenamate over 10 min and then gave 0.23 mg/h per kg for the remainder of the 4 h. Ventilation increased progressively from a control value of 515 +/- 72 ml/min per kg to a maximum of 753 +/- 100 ml/min per kg after 3h of infusion (P less than 0.05) due to an increased breathing rate; the effects were similar during both high- and low-voltage electrocortical activity. There were no significant changes in tidal volume, heart rate, blood pressure, arterial pH or PaCO2, the increased ventilation resulted from either an increase in dead space ventilation or an increase in CO2 production. This study indicates that meclofenamate causes an increase in ventilation in <span class="hlt">lambs</span> but no changes in pH of PaCO2. The mechanism and site of action remain to be defined. PMID:2507622</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22989948','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22989948"><span id="translatedtitle">Study of stress-induced velocity variation in concrete under direct tensile force and monitoring of the damage level by using thermally-compensated Coda <span class="hlt">Wave</span> Interferometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yuxiang; Abraham, Odile; Grondin, Frédéric; Loukili, Ahmed; Tournat, Vincent; Le Duff, Alain; Lascoup, Bertrand; Durand, Olivier</p> <p>2012-12-01</p> <p>In this paper, we describe an experimental study of concrete behavior under a uniaxial tensile load by use of the thermally-compensated Coda <span class="hlt">Wave</span> Interferometry (CWI) analysis. Under laboratory conditions, uniaxial tensile load cycles are imposed on a cylindrical concrete specimen, with continuous ultrasonic measurements being recorded within the scope of bias control protocols. A thermally-compensated CWI analysis of multiple scattering <span class="hlt">waves</span> is performed in order to evaluate the stress-induced velocity variation. Concrete behavior under a tensile load can then be studied, along with CWI results from both its elastic performance (<span class="hlt">acoustoelasticity</span>) and plastic performance (microcracking corresponding to the Kaiser effect). This work program includes a creep test with a sustained, high tensile load; the <span class="hlt">acoustoelastic</span> coefficients are estimated before and after conducting the creep test and then used to demonstrate the effect of creep load. PMID:22989948</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/902624','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/902624"><span id="translatedtitle">Looping through the <span class="hlt">Lamb</span> Shift</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hazi, A U</p> <p>2007-02-06</p> <p>Sometimes in science, a small measurement can have big ramifications. For a team of Livermore scientists, such was the case when they measured a small shift in the spectrum of extremely ionized atoms of uranium. The measurement involves the <span class="hlt">Lamb</span> shift, a subtle change in the energy of an electron orbiting an atom's nucleus. The precision of the Livermore result was 10 times greater than that of existing measurements, making it the best measurement to date of a complicated correction to the simplest quantum description of how atoms behave. The measurement introduces a new realm in the search for deviations between the theory of quantum electrodynamics (QED), which is an extension of quantum mechanics, and the real world. Such deviations, if discovered, would have far-reaching consequences, indicating that QED is not a fundamental theory of nature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24420763','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24420763"><span id="translatedtitle">Metabolic profile in Chilota <span class="hlt">lambs</span> grazing Calafatal.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gallardo, María Asunción; Noro, Mirela; De la Barra, Rodrigo; Pulido, Rubén</p> <p>2014-04-01</p> <p>The aim of this study was to determine the productive and metabolic response in Chilota <span class="hlt">lambs</span> grazing Calafatal or naturalized pasture. The experiment was conducted at the Experimental Station Butalcura (INIA, Chiloé) during October, November, and December 2011. Eight Chilota and six Suffolk Down 2-month-old <span class="hlt">lambs</span>, uncastrated males, no twin, were located to graze a typical secondary succession of the Chiloé Archipelago, as a Calafatal (a secondary succession which derivates from human intervention on native forest in Chiloé Archipelago). Simultaneously, eight male 2-month-old Chilota <span class="hlt">lambs</span> were located to graze a naturalized pasture, another secondary succession derived from human intervention on native forest in Chiloé Archipelago. Animals had free access to water sources. Measurements were performed one time a month, for three consecutive months for productive indicators: live weight, average daily gain and body condition score, and blood indicators of protein and energetic metabolism. Productive and metabolic response was similar between both types of pastures (P > 0.05). However, Chilota and Suffolk Down <span class="hlt">lambs</span> grazing Calafatal showed higher plasma concentrations of βOH-butyrate, but lower non-esterified fatty acids (NEFA) than Chilota <span class="hlt">lambs</span> grazing naturalized pasture (P < 0.05). Chilota <span class="hlt">lambs</span> grazing naturalized pasture showed the highest plasma concentrations of NEFA and urea (P < 0.05). It was concluded that, under the conditions of the study, Chilota <span class="hlt">lambs</span> grazing naturalized pasture, which had higher contents of crude protein and metabolizable energy, showed better metabolic balance, but not performance, than Chilota and Suffolk Down <span class="hlt">lambs</span> grazing Calafatal. PMID:24420763</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JKPS...65.1858L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JKPS...65.1858L&link_type=ABSTRACT"><span id="translatedtitle">Propagation of ultrasonic guided <span class="hlt">waves</span> in an acrylic plate as a cortical-bone-mimicking phantom</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Kang Il; Choi, Bok Kyoung</p> <p>2014-12-01</p> <p>The present study aims to investigate the propagation of ultrasonic guided <span class="hlt">waves</span> in an acrylic plate as a cortical-bone-mimicking phantom. The velocities of the guided <span class="hlt">waves</span> in a 5-mm-thick acrylic plate were measured by using the axial transmission technique. A pure A0 <span class="hlt">Lamb</span> mode could be successfully launched in the 5-mm-thick acrylic plate through a time reversal process of <span class="hlt">Lamb</span> <span class="hlt">waves</span>, consistent with the fact that the time reversal process can automatically compensate for the dispersive nature of <span class="hlt">Lamb</span> <span class="hlt">waves</span>. The experimental velocities of the slow guided <span class="hlt">wave</span> (SGW) and the time-reversed <span class="hlt">Lamb</span> <span class="hlt">wave</span> were found to be in reasonable agreement with the theoretical group velocity of the A0 <span class="hlt">Lamb</span> mode, suggesting that both the SGW and the time-reversed <span class="hlt">Lamb</span> <span class="hlt">wave</span> excited in the 5-mm-thick acrylic plate correspond to the A0 <span class="hlt">Lamb</span> mode. These results suggest that the time reversal process of <span class="hlt">Lamb</span> <span class="hlt">waves</span> can be usefully applied to noninvasive characterization of long cortical bones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22063971','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22063971"><span id="translatedtitle">Dietary tannins improve <span class="hlt">lamb</span> meat colour stability.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Luciano, G; Monahan, F J; Vasta, V; Biondi, L; Lanza, M; Priolo, A</p> <p>2009-01-01</p> <p>Fourteen male Comisana <span class="hlt">lambs</span> were divided into two groups at 45days of age: <span class="hlt">lambs</span> fed a concentrate diet (C), or <span class="hlt">lambs</span> fed the same concentrate with the addition of quebracho (Schinopsis lorentzii) tannins (T). Sheep were slaughtered at 105days of age. Lipid oxidation, colour coordinates, haem pigment concentration, and metmyoglobin percentages were measured on minced semimembranosus muscle (SM) over 14days of refrigerated storage in a high oxygen modified atmosphere. Tannin supplementation increased (P<0.01) a(∗) values and reduced (P<0.01) b(∗) values of the SM when compared to C. Lower hue angles (P<0.001) and metmyoglobin formation (P=0.07) were observed in <span class="hlt">lamb</span> from T-fed compared to C-fed sheep during the 14-days storage period. Furthermore, feeding T resulted in greater (P<0.001) haem pigment concentrations in the SM during refrigerated storage; however, diet had no (P=0.28) effect on lipid oxidation. Therefore, including quebracho tannins in sheep diets can improve meat colour stability of fresh <span class="hlt">lamb</span> during extended refrigerated storage. PMID:22063971</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=287209','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=287209"><span id="translatedtitle">Changes in tail length between docking and weaning of <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>This study was conducted with crossbred <span class="hlt">lambs</span> (n = 109 female and 120 male) to quantify tail length at docking and weaning. <span class="hlt">Lambs</span> were born in April of one year and weaned at ˜ 125 d of age. Within 24 h after birth, <span class="hlt">lambs</span> were weighed and ear tagged, and rubber rings were applied to dock tails. R...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec59-302.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec59-302.pdf"><span id="translatedtitle">7 CFR 59.302 - Mandatory weekly reporting for <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... slaughtered; (3) The quantity of <span class="hlt">lambs</span> delivered under a formula marketing arrangement that were slaughtered... and discounts (including those associated with weight, quality grade, yield grade, or type of <span class="hlt">lamb</span>... <span class="hlt">lambs</span> purchased through a formula marketing arrangement and slaughtered during the prior slaughter...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec59-302.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec59-302.pdf"><span id="translatedtitle">7 CFR 59.302 - Mandatory weekly reporting for <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... slaughtered; (3) The quantity of <span class="hlt">lambs</span> delivered under a formula marketing arrangement that were slaughtered... and discounts (including those associated with weight, quality grade, yield grade, or type of <span class="hlt">lamb</span>... <span class="hlt">lambs</span> purchased through a formula marketing arrangement and slaughtered during the prior slaughter...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=246089','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=246089"><span id="translatedtitle">Enhancing nutritiousness of <span class="hlt">lamb</span> meat and preventing selenium deficiency.</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p><span class="hlt">Lamb</span> meat is a naturally flavorful and nutritious product. Our research indicates that feeding a specific wheat-milling coproduct will enhance the nutritiousness of <span class="hlt">lamb</span>, potentially add monetary value to <span class="hlt">lamb</span>, and prevent Se deficiency. Selenium is an essential micromineral, and Se supplementation ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title21-vol8/pdf/CFR-2010-title21-vol8-sec880-5640.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title21-vol8/pdf/CFR-2010-title21-vol8-sec880-5640.pdf"><span id="translatedtitle">21 CFR 880.5640 - <span class="hlt">Lamb</span> feeding nipple.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-04-01</p> <p>... 21 Food and Drugs 8 2010-04-01 2010-04-01 false <span class="hlt">Lamb</span> feeding nipple. 880.5640 Section 880.5640... Devices § 880.5640 <span class="hlt">Lamb</span> feeding nipple. (a) Identification. A <span class="hlt">lamb</span> feeding nipple is a device intended for use as a feeding nipple for infants with oral or facial abnormalities. (b) Classification. Class...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=319264','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=319264"><span id="translatedtitle">Genetic evaluation of weaning weight and probability of <span class="hlt">lambing</span> at 1 year of age in Targhee <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The objective of this study was to investigate genetic control of 120-day weaning weight and the probability of <span class="hlt">lambing</span> at 1 year of age in Targhee ewe <span class="hlt">lambs</span>. Records of 5,967 ewe <span class="hlt">lambs</span> born from 1989 to 2012 and first exposed to rams for breeding at approximately 7 months of age were analyzed. Reco...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AIPC..975...55J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AIPC..975...55J"><span id="translatedtitle">Guided <span class="hlt">Waves</span> with and Without Dispersion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Joshi, Narayan R.</p> <p>2008-02-01</p> <p>In the application of elastic <span class="hlt">waves</span> of ultrasonic frequencies for nondestructive evaluations of industrial components and welded structures various types of <span class="hlt">waves</span> like Rayleigh <span class="hlt">waves</span>, Surface <span class="hlt">waves</span>, Longitudinal body <span class="hlt">waves</span>, Shear body <span class="hlt">waves</span>, and <span class="hlt">Lamb</span> <span class="hlt">waves</span> are used to detect defects in the objects under investigation. In many cases these <span class="hlt">waves</span> travel in bounded media and are affected by boundaries. Because they are guided by boundaries of objects under investigation, they are called sometimes guided <span class="hlt">waves</span> or waveguides at other times. Some of these guided <span class="hlt">waves</span> are dispersive in character while others are nondispersive. Efforts are made here to distinguish between guided <span class="hlt">waves</span> with dispersion and those without dispersion.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26946479','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26946479"><span id="translatedtitle">Understanding consumers' perception of <span class="hlt">lamb</span> meat using free word association.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Andrade, Juliana Cunha; de Aguiar Sobral, Louise; Ares, Gastón; Deliza, Rosires</p> <p>2016-07-01</p> <p>The aims of the present study were to gather information about Brazilian consumers' perception of <span class="hlt">lamb</span> meat and to study whether the perception is affected by the consumption frequency of this type of meat. A total of 1025 Brazilian consumers completed word association task with <span class="hlt">lamb</span> meat. The elicited words were analyzed using inductive coding. Participants' associations with <span class="hlt">lamb</span> meat were mainly related to sensory characteristics and hedonic attitudes and feelings, indicating that they might be the main motivations for consuming this product. Participants strongly associated <span class="hlt">lamb</span> meat with special consumption occasions, which suggests that lack of perceived appropriateness for everyday consumption situations might be a barrier for increasing <span class="hlt">lamb</span> meat consumption. Conceptualization of <span class="hlt">lamb</span> meat was strongly affected by frequency of consumption of this product. Results from the present work provide a comprehensive insight on Brazilian consumers' perception of <span class="hlt">lamb</span> meat, which can be used to develop strategies to increase its consumption and improve profitability. PMID:26946479</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AIPC..615.1651M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AIPC..615.1651M"><span id="translatedtitle">Dispersion of Rayleigh <span class="hlt">waves</span> in titanium alloy resulting from inhomogeneous residual stress induced by low plasticity burnishing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Man, C.-S.; Koo, L.; Shepard, M. J.</p> <p>2002-05-01</p> <p>We explore the possibility of using the dispersion of Rayleigh <span class="hlt">waves</span> for nondestructive inspection of the layer of inhomogeneous residual stress induced by low plasticity burnishing (LPB) on Ti-6Al-4V samples, which inherit mirror-smooth surfaces from the LPB treatment. Our findings suggest that, while the <span class="hlt">acoustoelastic</span> effect is very small in Ti-6Al-4V, the magnitude of the stress gradient involved still leads to a measurable Rayleigh-<span class="hlt">wave</span> dispersion, from which information on the stress present could be inferred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec65-190.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec65-190.pdf"><span id="translatedtitle">7 CFR 65.190 - <span class="hlt">Lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 7 Agriculture 3 2013-01-01 2013-01-01 false <span class="hlt">Lamb</span>. 65.190 Section 65.190 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec65-190.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec65-190.pdf"><span id="translatedtitle">7 CFR 65.190 - <span class="hlt">Lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 7 Agriculture 3 2011-01-01 2011-01-01 false <span class="hlt">Lamb</span>. 65.190 Section 65.190 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec65-170.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec65-170.pdf"><span id="translatedtitle">7 CFR 65.170 - Ground <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 7 Agriculture 3 2013-01-01 2013-01-01 false Ground <span class="hlt">lamb</span>. 65.170 Section 65.170 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec65-190.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec65-190.pdf"><span id="translatedtitle">7 CFR 65.190 - <span class="hlt">Lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 7 Agriculture 3 2014-01-01 2014-01-01 false <span class="hlt">Lamb</span>. 65.190 Section 65.190 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec65-190.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec65-190.pdf"><span id="translatedtitle">7 CFR 65.190 - <span class="hlt">Lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 7 Agriculture 3 2010-01-01 2010-01-01 false <span class="hlt">Lamb</span>. 65.190 Section 65.190 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec65-170.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec65-170.pdf"><span id="translatedtitle">7 CFR 65.170 - Ground <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 7 Agriculture 3 2012-01-01 2012-01-01 false Ground <span class="hlt">lamb</span>. 65.170 Section 65.170 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec65-170.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec65-170.pdf"><span id="translatedtitle">7 CFR 65.170 - Ground <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 7 Agriculture 3 2010-01-01 2010-01-01 false Ground <span class="hlt">lamb</span>. 65.170 Section 65.170 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec65-190.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec65-190.pdf"><span id="translatedtitle">7 CFR 65.190 - <span class="hlt">Lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 7 Agriculture 3 2012-01-01 2012-01-01 false <span class="hlt">Lamb</span>. 65.190 Section 65.190 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec65-170.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec65-170.pdf"><span id="translatedtitle">7 CFR 65.170 - Ground <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 7 Agriculture 3 2011-01-01 2011-01-01 false Ground <span class="hlt">lamb</span>. 65.170 Section 65.170 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec65-170.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec65-170.pdf"><span id="translatedtitle">7 CFR 65.170 - Ground <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 7 Agriculture 3 2014-01-01 2014-01-01 false Ground <span class="hlt">lamb</span>. 65.170 Section 65.170 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=241924','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=241924"><span id="translatedtitle">Finishing <span class="hlt">Lambs</span> and Goat Kids on Pasture</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Producing goats and <span class="hlt">lambs</span> for ethnic markets offers an economic opportunity for small farm producers in the Appalachian Region of the U.S. There are a variety of forages used in goat and sheep production systems. Overall, nutrients available to ruminants depend upon the types and combinations of p...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/1582944','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/1582944"><span id="translatedtitle"><span class="hlt">Lambs</span> form preferences for nonnutritive flavors paired with glucose.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burritt, E A; Provenza, F D</p> <p>1992-04-01</p> <p>We studied <span class="hlt">lambs</span>' preferences for nonnutritive flavors that were paired with a glucose solution. On the 1st d of the experiment, <span class="hlt">lambs</span> were offered a saccharin solution flavored with either orange or grape. The following day <span class="hlt">lambs</span> received a glucose solution containing either orange or grape flavor. <span class="hlt">Lambs</span> that had received grape and saccharin on d 1 received orange and glucose on d 2, and the reverse was true for the remaining <span class="hlt">lambs</span>. Conditioning lasted 10 d; odd days were like the first and even days like the second. After conditioning, when <span class="hlt">lambs</span> were offered a choice between orange- or grape-flavored water without sweeteners, <span class="hlt">lambs</span> chose the flavor that had been paired with glucose. We also tested the initial hedonic response of naive <span class="hlt">lambs</span> to the flavor of glucose and saccharin solutions. <span class="hlt">Lambs</span> exhibited no initial preference. Our results indicate that <span class="hlt">lambs</span> preferred the flavor that was paired with glucose (calories). Furthermore, results of this study suggest that ruminants may not innately recognize specific chemical constituents in foods or select diets based on initial hedonic value. Rather, learning plays a key role in the formation of dietary preference. PMID:1582944</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21408739','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21408739"><span id="translatedtitle">Cooperative <span class="hlt">Lamb</span> shift and the cooperative decay rate for an initially detuned phased state</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Friedberg, Richard; Manassah, Jamal T.</p> <p>2010-04-15</p> <p>The cooperative <span class="hlt">Lamb</span> shift (CLS) is hard to measure because in samples much larger than a resonant wavelength it is much smaller, for an initially prepared resonantly phased state, than the cooperative decay rate (CDR). We show, however, that if the phasing of the initial state is detuned so that the spatial <span class="hlt">wave</span> vector is k{sub 1} congruent with k{sub 0{+-}}O((1/R)) (where k{sub 0}={omega}{sub 0}/c is the resonant frequency), the CLS grows to 'giant' magnitudes making it comparable to the CDR. Moreover, for certain controlled values of detuning, the initial CDR becomes small so that the dynamical <span class="hlt">Lamb</span> shift (DLS) can be measured over a considerable period of time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9520E..06B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9520E..06B"><span id="translatedtitle">Off-diagonal photonic <span class="hlt">Lamb</span> shift in reactively coupled waveguide-resonator system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bernard, M.; Ramiro-Manzano, F.; Prtljaga, N.; Pucker, G.; Pavesi, L.; Carusotto, I.; Ghulinyan, M.</p> <p>2015-06-01</p> <p>We report on a joint theoretical and experimental study of an analogue of the <span class="hlt">Lamb</span> shift in the photonic framework. The platform is an integrated photonic device consisting of a single mode waveguide vertically coupled to a disk-shaped microresonator. The presence of a neighboring waveguide induces a reactive inter-mode coupling in the resonator, an effect analogous to an off-diagonal <span class="hlt">Lamb</span> shift from atomic physics. Waveguide mediated coupling of different radial families results in peculiar Fano lineshapes in the waveguide transmission spectra, which manifests for different relative frequency shifts of the modes at different azimuthal numbers. Finally, a non-linear model for the dinamic tuning of the Fano lineshape under continuous <span class="hlt">wave</span> pumping conditions is proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1680406','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1680406"><span id="translatedtitle">Responses of Pregnant Ewes and Young <span class="hlt">Lambs</span> to Cold Exposure</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Olson, David P.; Parker, C.F.; LeaMaster, B.R.; Dixon, J.E.</p> <p>1987-01-01</p> <p>The effects of cold stress were studied in pregnant ewes during the last three weeks of gestation and in their progeny during the first three days of life. In general, ewes were unaffected by treatment whereas changes were observed in the cold-stressed <span class="hlt">lambs</span>. Cold-induced changes in <span class="hlt">lambs</span> included physical weakness, depression, and poor nursing response. Serum concentrations of glucose and insulin were lowered whereas concentrations of blood urea nitrogen, alkaline phosphatase, aspartate aminotransferase, lactate dehydrogenase, triglycerides, and cortisol tended to be higher in cold exposed <span class="hlt">lambs</span>. The mortality rate was higher (40%) in cold-stressed <span class="hlt">lambs</span> than in <span class="hlt">lambs</span> kept at warmer temperatures (10%). At necropsy, cold-exposed <span class="hlt">lambs</span> had reduced amounts of adipose tissue in perirenal areas, and extensive subcutaneous hemorrhages and edema in the distal portions of the thoracic and pelvic limbs. ImagesFigure 1. PMID:17422756</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040121063','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040121063"><span id="translatedtitle">Effect of Stress on Energy Flux Deviation of Ultrasonic <span class="hlt">Waves</span> in Ultrasonic <span class="hlt">Waves</span> in GR/EP Composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prosser, William H.; Kriz, R. D.; Fitting, Dale W.</p> <p>1990-01-01</p> <p>Ultrasonic <span class="hlt">waves</span> suffer energy flux deviation in graphite/epoxy because of the large anisotropy. The angle of deviation is a function of the elastic coefficients. For nonlinear solids, these coefficients and thus the angle of deviation is a function of stress. <span class="hlt">Acoustoelastic</span> theory was used to model the effect of stress on flux deviation for unidirectional T300/5208 using previously measured elastic coefficients. Computations were made for uniaxial stress along the x3 axis fiber axis) and the x1 axis for <span class="hlt">waves</span> propagating in the x1x3 plane. These results predict a shift as large as three degrees for the quasi-transverse <span class="hlt">wave</span>. The shift in energy flux offers new nondestructive technique of evaluating stress in composites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26723309','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26723309"><span id="translatedtitle">Effect of refracted light distribution on the photoelastic generation of zero-group velocity <span class="hlt">Lamb</span> modes in optically low-absorbing plates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Raetz, Samuel; Laurent, Jérôme; Dehoux, Thomas; Royer, Daniel; Audoin, Bertrand; Prada, Claire</p> <p>2015-12-01</p> <p>Zero-group velocity (ZGV) <span class="hlt">Lamb</span> modes are associated with sharp local acoustic resonances and allow, among other features, local measurement of Poisson's ratio. While the thermoelastic generation of <span class="hlt">Lamb</span> <span class="hlt">waves</span> in metal plates has been widely studied, the case of materials of low-optical absorption remains unexplored. In materials such as glasses, the generation of bulk elastic <span class="hlt">waves</span> has been demonstrated to be sensitive to the refracted light distribution. In this paper, a detailed analysis of the effect of light refraction on the laser-based generation of ZGV <span class="hlt">Lamb</span> modes is presented. Experiments are performed on a bare glass plate without the need for an additional layer for light absorption or reflection. Using an appropriate tilted volume source, it is shown that the laser-ultrasonic technique allows non-contact measurement of the Poisson's ratio. PMID:26723309</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26321129','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26321129"><span id="translatedtitle">Enteric viral infections in <span class="hlt">lambs</span> or kids.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martella, V; Decaro, N; Buonavoglia, C</p> <p>2015-12-14</p> <p>Diarrhoea in <span class="hlt">lambs</span> and kids is often a complex, multi-factorial syndrome. Common infectious causes of diarrhoea in <span class="hlt">lambs</span> and kids during the first month of life are of bacterial or parasite nature. However, despite appreciable improvements in management practices and prevention and treatment strategies over the last decades, diarrhoea is still a common and costly syndrome affecting newborn small ruminants. Recent advances in the diagnostics and metagenomic investigations of the enteric environment have allowed discovering a number of novel viruses, although their pathobiological properties remain largely unknown. Assessing more in depth the impact of these viruses on the health and productions of these livestock animals is necessary and requires the development of accurate diagnostic tools and updating of the diagnostic algorithms of enteric pathological conditions. PMID:26321129</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=268667','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=268667"><span id="translatedtitle">Sodium chlorate reduces presence of Escherichia coli in feces of <span class="hlt">lambs</span> and ewes managed in shed-<span class="hlt">lambing</span> systems</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Our objective was to establish doses of orally-administered NaClO3 that reduced presence of generic Escherichia coli in intestines of ewes and neonatal <span class="hlt">lambs</span> managed in a shed-<span class="hlt">lambing</span> system. Neonatal <span class="hlt">lambs</span> (n = 32; age = 7.1 ± 1.2 d; BW = 6.8 ± 1.0 kg) and yearling ewes (n = 44; BW = 74.8 ± 5.6 kg)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=545989','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=545989"><span id="translatedtitle">Vitamin D-responsive rickets in neonatal <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2004-01-01</p> <p>Abstract An unusual clinical presentation of rickets in nursing <span class="hlt">lambs</span> is described. Two sets of twin nursing <span class="hlt">lambs</span> were presented for enlarged joints and mild angular deformity. Rickets was suspected, based on radiographic evidence. Vitamin D deficiency was determined to be the cause, based on serum concentration and response to therapy. PMID:15532884</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=249697','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=249697"><span id="translatedtitle">Enhancement technology improves palatability of normal and callipyge <span class="hlt">lamb</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>This research was to determine if BPI Processing Technology improved palatability of normal (NN) and callipyge (CN) <span class="hlt">lamb</span> meat and determine the mechanism by which palatability was improved. Ten ewe and 10 wether <span class="hlt">lambs</span> of each phenotype were harvested and carcass traits were assessed by a trained eva...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4478491','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4478491"><span id="translatedtitle"><span class="hlt">Lamb</span> Production Costs: Analyses of Composition and Elasticities Analysis of <span class="hlt">Lamb</span> Production Costs</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Raineri, C.; Stivari, T. S. S.; Gameiro, A. H.</p> <p>2015-01-01</p> <p>Since <span class="hlt">lamb</span> is a commodity, producers cannot control the price of the product they sell. Therefore, managing production costs is a necessity. We explored the study of elasticities as a tool for basing decision-making in sheep production, and aimed at investigating the composition and elasticities of <span class="hlt">lamb</span> production costs, and their influence on the performance of the activity. A representative sheep production farm, designed in a panel meeting, was the base for calculation of <span class="hlt">lamb</span> production cost. We then performed studies of: i) costs composition, and ii) cost elasticities for prices of inputs and for zootechnical indicators. Variable costs represented 64.15% of total cost, while 21.66% were represented by operational fixed costs, and 14.19% by the income of the factors. As for elasticities to input prices, the opportunity cost of land was the item to which production cost was more sensitive: a 1% increase in its price would cause a 0.2666% increase in <span class="hlt">lamb</span> cost. Meanwhile, the impact of increasing any technical indicator was significantly higher than the impact of rising input prices. A 1% increase in weight at slaughter, for example, would reduce total cost in 0.91%. The greatest obstacle to economic viability of sheep production under the observed conditions is low technical efficiency. Increased production costs are more related to deficient zootechnical indexes than to high expenses. PMID:26104531</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26104531','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26104531"><span id="translatedtitle"><span class="hlt">Lamb</span> Production Costs: Analyses of Composition and Elasticities Analysis of <span class="hlt">Lamb</span> Production Costs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Raineri, C; Stivari, T S S; Gameiro, A H</p> <p>2015-08-01</p> <p>Since <span class="hlt">lamb</span> is a commodity, producers cannot control the price of the product they sell. Therefore, managing production costs is a necessity. We explored the study of elasticities as a tool for basing decision-making in sheep production, and aimed at investigating the composition and elasticities of <span class="hlt">lamb</span> production costs, and their influence on the performance of the activity. A representative sheep production farm, designed in a panel meeting, was the base for calculation of <span class="hlt">lamb</span> production cost. We then performed studies of: i) costs composition, and ii) cost elasticities for prices of inputs and for zootechnical indicators. Variable costs represented 64.15% of total cost, while 21.66% were represented by operational fixed costs, and 14.19% by the income of the factors. As for elasticities to input prices, the opportunity cost of land was the item to which production cost was more sensitive: a 1% increase in its price would cause a 0.2666% increase in <span class="hlt">lamb</span> cost. Meanwhile, the impact of increasing any technical indicator was significantly higher than the impact of rising input prices. A 1% increase in weight at slaughter, for example, would reduce total cost in 0.91%. The greatest obstacle to economic viability of sheep production under the observed conditions is low technical efficiency. Increased production costs are more related to deficient zootechnical indexes than to high expenses. PMID:26104531</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26973772','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26973772"><span id="translatedtitle">A case presentation of spider <span class="hlt">lamb</span> syndrome in a Kermanian breed <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nazem, Mohammad Naser; Shojaei, Bahador; Asadi, Akbar; Hasanzadeh, Mohammad</p> <p>2015-01-01</p> <p>Skeletal abnormalities are most often used to describe defects in the arms or legs that are associated with genes or chromosomes, or that occur due to an event that happens during pregnancy. Spider <span class="hlt">lamb</span> syndrome (SLS) is a congenital disorder in sheep breeding that is recognized by some deformities in skeletal system especially in the limbs. A dead day-old cross-breed white <span class="hlt">lamb</span> with deformed limbs was referred to the anatomy hall of the Veterinary Faculty of Shahid Bahonar University of Kerman. In the external examination, the <span class="hlt">lamb</span> was very skinny and in the facial region, superior brachygnathia with a slight Roman nose were observed. Metacarpal and metatarsal regions were more elongated than that expected. Also Metacarpal and metatarsal bones were as long as the antebrachial and crural regions, respectively. This paper, the first report of this syndrome in Iran, described the anatomic and radiographic features of the skeletal deformities in a day-old dead Kermanian breed <span class="hlt">lamb</span>. PMID:26973772</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4769342','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4769342"><span id="translatedtitle">A case presentation of spider <span class="hlt">lamb</span> syndrome in a Kermanian breed <span class="hlt">lamb</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nazem, Mohammad Naser; Shojaei, Bahador; Asadi, Akbar; Hasanzadeh, Mohammad</p> <p>2015-01-01</p> <p>Skeletal abnormalities are most often used to describe defects in the arms or legs that are associated with genes or chromosomes, or that occur due to an event that happens during pregnancy. Spider <span class="hlt">lamb</span> syndrome (SLS) is a congenital disorder in sheep breeding that is recognized by some deformities in skeletal system especially in the limbs. A dead day-old cross-breed white <span class="hlt">lamb</span> with deformed limbs was referred to the anatomy hall of the Veterinary Faculty of Shahid Bahonar University of Kerman. In the external examination, the <span class="hlt">lamb</span> was very skinny and in the facial region, superior brachygnathia with a slight Roman nose were observed. Metacarpal and metatarsal regions were more elongated than that expected. Also Metacarpal and metatarsal bones were as long as the antebrachial and crural regions, respectively. This paper, the first report of this syndrome in Iran, described the anatomic and radiographic features of the skeletal deformities in a day-old dead Kermanian breed <span class="hlt">lamb</span>. PMID:26973772</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7294476','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7294476"><span id="translatedtitle">Diarrhea in <span class="hlt">lambs</span> experimentally infected with Cryptosporidium isolated from calves.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tzipori, S; Angus, K W; Gray, E W; Campbell, I; Allan, F</p> <p>1981-08-01</p> <p>Two to 5 days after oral inoculation with Cryptosporidium obtained from infected calves, 7 newborn specific-pathogen-free <span class="hlt">lambs</span> became depressed and anorectic and developed diarrhea. Four moribund <span class="hlt">lambs</span> were killed within 3 days after onset of illness, and the 3 other <span class="hlt">lambs</span> died after protracted intermittent diarrhea and reduced milk intake, which lasted up to 14 days. The small and large intestines were heavily infected with Cryptosporidium, with the terminal portion of the ileum being the most severely affected. Histologic examination revealed villous atrophy, with considerable fusion and epithelial cross-bridging between villi. <span class="hlt">Lambs</span> infected at 5 to 20 days of age had less severe clinical signs of disease, with intermittent diarrhea, reduced milk intake, and growth retardation. <span class="hlt">Lambs</span> infected at 30 days of age became infected with the organism, but did not develop clinical signs of disease or growth retardation. PMID:7294476</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22060921','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22060921"><span id="translatedtitle">Preference structure for <span class="hlt">lamb</span> meat consumers. A Spanish case study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bernabéu, Rodolfo; Tendero, Antonio</p> <p>2005-11-01</p> <p>There is a current tendency in the European Union member countries to cut down on meat consumption. This tendency is not due as much to the traditional income-price factor, but to other attributes whose influence is gaining relative importance. Some of them are: quality, image, health, food safety and changes in people's taste. In addition, the relative importance of different attributes valued by the consumer must be weighed in order to develop marketing strategies which increase <span class="hlt">lamb</span> meat consumption. In order to determine these preferences, 400 consumers were asked to evaluate different attributes (price, certification, origin, and commercial type) of <span class="hlt">lamb</span> meat. Results obtained by means of conjoint analysis techniques show that regular consumers as well as occasional ones show a preference for <span class="hlt">lamb</span> meat type. In this sense, a market share simulation of preferred (suckling and "ternasco") types proved that regular consumers generally prefer suckling <span class="hlt">lamb</span> to "ternasco" <span class="hlt">lamb</span> when both are from Castilla-La Mancha. PMID:22060921</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15542470','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15542470"><span id="translatedtitle">Source and level of supplemental protein for growing <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dabiri, N; Thonney, M L</p> <p>2004-11-01</p> <p>Two 3 x 2 factorial growth trials and a companion metabolism trial with 13, 15, or 17% dietary CP (DM basis), with or without 3% of the DM replaced with slowly degraded menhaden fish meal, were conducted to determine if level of dietary protein influences whether slowly degraded protein improves <span class="hlt">lamb</span> growth and protein use. The growth trials included 32 and 34 pens of two weanling <span class="hlt">lambs</span> initially weighing 23 to 26 kg and fed for 42 d. The metabolism trial included 12 additional <span class="hlt">lambs</span> fed in metabolism cages with a 2-wk adjustment period, a 1-wk preliminary period, and a 7-d collection period. Plasma urea N (PUN) was measured in all <span class="hlt">lambs</span> at the conclusion of the second growth trial and at the end of the metabolism trial. There was a protein level x protein source interaction (P = 0.05) for PUN of the 12 <span class="hlt">lambs</span> in the metabolism trial but not for the 68 <span class="hlt">lambs</span> in the second growth trial. Replacement of part of the soybean meal protein with protein from fish meal did not affect ADG or G:F at any protein level, but it lowered (P = 0.08) PUN in the second growth trial. Plasma urea N values were higher (P = 0.002) in <span class="hlt">lambs</span> fed diets with 15 or 17% CP; however, ADG (P = 0.037 in Exp. 1 and P = 0.055 in Exp. 2), and G:F (P = 0.094 in Exp. 1 and P = 0.003 in Exp. 2) were lower for <span class="hlt">lambs</span> fed the diets with 13% CP. There was little difference in ADG or G:F between <span class="hlt">lambs</span> fed the diets with 15 or 17% CP, suggesting that a CP level of 15% with supplemental protein from soybean meal would be optimal for 25- to 40-kg growing Finnsheep x Dorset <span class="hlt">lambs</span>. PMID:15542470</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7231926','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7231926"><span id="translatedtitle">Effective immunization of <span class="hlt">lambs</span> against enterotoxaemia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cameron, C M</p> <p>1980-12-01</p> <p>In contrast to adult sheep, 2- to 3-month-old <span class="hlt">lambs</span> do not respond well to a single injection of Clostridium perfringens Type D oil adjuvant epsilon toxoid. This unresponsiveness can be overcome, however, by administering 2 injections of oil adjuvant vaccine or one injection of oil adjuvant followed 4 weeks later by an injection of alum-precipitated toxoid. The latter procedure evokes protective antitoxin levels which persist for 8 months, and a booster injection of alum-precipitated toxoid given at this stage results in an immunity which lasts for at least 1 year. PMID:7231926</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4893601','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4893601"><span id="translatedtitle">Comb-locked <span class="hlt">Lamb</span>-dip spectrometer</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gatti, Davide; Gotti, Riccardo; Gambetta, Alessio; Belmonte, Michele; Galzerano, Gianluca; Laporta, Paolo; Marangoni, Marco</p> <p>2016-01-01</p> <p>Overcoming the Doppler broadening limit is a cornerstone of precision spectroscopy. Nevertheless, the achievement of a Doppler-free regime is severely hampered by the need of high field intensities to saturate absorption transitions and of a high signal-to-noise ratio to detect tiny <span class="hlt">Lamb</span>-dip features. Here we present a novel comb-assisted spectrometer ensuring over a broad range from 1.5 to 1.63 μm intra-cavity field enhancement up to 1.5 kW/cm2, which is suitable for saturation of transitions with extremely weak electric dipole moments. Referencing to an optical frequency comb allows the spectrometer to operate with kHz-level frequency accuracy, while an extremely tight locking of the probe laser to the enhancement cavity enables a 10−11 cm−1 absorption sensitivity to be reached over 200 s in a purely dc direct-detection-mode at the cavity output. The particularly simple and robust detection and operating scheme, together with the wide tunability available, makes the system suitable to explore thousands of lines of several molecules never observed so far in a Doppler-free regime. As a demonstration, <span class="hlt">Lamb</span>-dip spectroscopy is performed on the P(15) line of the 01120-00000 band of acetylene, featuring a line-strength below 10−23 cm/mol and an Einstein coefficient of 5 mHz, among the weakest ever observed. PMID:27263858</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27263858','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27263858"><span id="translatedtitle">Comb-locked <span class="hlt">Lamb</span>-dip spectrometer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gatti, Davide; Gotti, Riccardo; Gambetta, Alessio; Belmonte, Michele; Galzerano, Gianluca; Laporta, Paolo; Marangoni, Marco</p> <p>2016-01-01</p> <p>Overcoming the Doppler broadening limit is a cornerstone of precision spectroscopy. Nevertheless, the achievement of a Doppler-free regime is severely hampered by the need of high field intensities to saturate absorption transitions and of a high signal-to-noise ratio to detect tiny <span class="hlt">Lamb</span>-dip features. Here we present a novel comb-assisted spectrometer ensuring over a broad range from 1.5 to 1.63 μm intra-cavity field enhancement up to 1.5 kW/cm(2), which is suitable for saturation of transitions with extremely weak electric dipole moments. Referencing to an optical frequency comb allows the spectrometer to operate with kHz-level frequency accuracy, while an extremely tight locking of the probe laser to the enhancement cavity enables a 10(-11) cm(-1) absorption sensitivity to be reached over 200 s in a purely dc direct-detection-mode at the cavity output. The particularly simple and robust detection and operating scheme, together with the wide tunability available, makes the system suitable to explore thousands of lines of several molecules never observed so far in a Doppler-free regime. As a demonstration, <span class="hlt">Lamb</span>-dip spectroscopy is performed on the P(15) line of the 01120-00000 band of acetylene, featuring a line-strength below 10(-23) cm/mol and an Einstein coefficient of 5 mHz, among the weakest ever observed. PMID:27263858</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...627183G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...627183G"><span id="translatedtitle">Comb-locked <span class="hlt">Lamb</span>-dip spectrometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gatti, Davide; Gotti, Riccardo; Gambetta, Alessio; Belmonte, Michele; Galzerano, Gianluca; Laporta, Paolo; Marangoni, Marco</p> <p>2016-06-01</p> <p>Overcoming the Doppler broadening limit is a cornerstone of precision spectroscopy. Nevertheless, the achievement of a Doppler-free regime is severely hampered by the need of high field intensities to saturate absorption transitions and of a high signal-to-noise ratio to detect tiny <span class="hlt">Lamb</span>-dip features. Here we present a novel comb-assisted spectrometer ensuring over a broad range from 1.5 to 1.63 μm intra-cavity field enhancement up to 1.5 kW/cm2, which is suitable for saturation of transitions with extremely weak electric dipole moments. Referencing to an optical frequency comb allows the spectrometer to operate with kHz-level frequency accuracy, while an extremely tight locking of the probe laser to the enhancement cavity enables a 10‑11 cm‑1 absorption sensitivity to be reached over 200 s in a purely dc direct-detection-mode at the cavity output. The particularly simple and robust detection and operating scheme, together with the wide tunability available, makes the system suitable to explore thousands of lines of several molecules never observed so far in a Doppler-free regime. As a demonstration, <span class="hlt">Lamb</span>-dip spectroscopy is performed on the P(15) line of the 01120-00000 band of acetylene, featuring a line-strength below 10‑23 cm/mol and an Einstein coefficient of 5 mHz, among the weakest ever observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22493959','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22493959"><span id="translatedtitle">Theory of <span class="hlt">Lamb</span> Shift in Muonic Hydrogen</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Karshenboim, Savely G.; Korzinin, Evgeny Yu.; Shelyuto, Valery A.; Ivanov, Vladimir G.</p> <p>2015-09-15</p> <p>There has been for a while a large discrepancy between the values of the proton charge radius measured by the <span class="hlt">Lamb</span> shift in muonic hydrogen and by other methods. It has already been clear that theory of muonic hydrogen is reliable at the level of this discrepancy and an error there cannot be a reason for the contradiction. Still the status of theory at the level of the uncertainty of the muonic-hydrogen experiment (which is two orders of magnitude below the discrepancy level) requires an additional clarification. Here, we revisit theory of the 2p − 2s <span class="hlt">Lamb</span> shift in muonic hydrogen. We summarize all the theoretical contributions in order α{sup 5}m, including pure quantum electrodynamics (QED) ones as well as those which involve the proton-structure effects. Certain enhanced higher-order effects are also discussed. We basically confirm former QED calculations of other authors, present a review of recent calculations of the proton-structure effects, and treat self-consistently higher-order proton-finite-size corrections. We also overview theory of the 2p states. Eventually, we derive a value of the root-mean-square proton charge radius. It is found to be 0.840 29(55) fm, which is slightly different from that previously published in the literature (0.840 87(39) fm [Antognini et al., Science 339, 417 (2013)])</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/9182393','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/9182393"><span id="translatedtitle">[Control of gastrointestinal helminthiasis in pasture-reared <span class="hlt">lambs</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chroust, K</p> <p>1997-03-01</p> <p>Two sheep herds kept in different geographic conditions with spring <span class="hlt">lambing</span> by the end of March and April (herd No. 1: 400 ewes, 600 metres above sea level; herd No. 2: 450 ewes, 300 metres above sea level) were examined. The dynamics of gastrointestinal nematode and Moniezia spp. cestode egg counts in samples taken regularly every 4 to 5 weeks was studied during the year 1995 with the intention to verify the system of effective control of these helminth infections under pasture conditions of <span class="hlt">lamb</span> rearing. In ewes a significant rise in gastrointestinal nematode egg counts was proved during the <span class="hlt">lambing</span> season, "spring rise phenomenon", and during the summer pasture until autumn months with maximum EPG values reaching 150 (Figs. 1 and 2). In <span class="hlt">lambs</span> that started grazing at 1 to 4 weeks of age, the excretion steeply rose to maximum EPG values 350 and 290, respectively, after 4 to 5 weeks of grazing (Figs. 1 and 2). In order to control these rising infections, ewes were treated with antihelmintic albendazol by the end of February (herd No. 1) and in March (herd No. 2) and <span class="hlt">lambs</span> during the first or third decade of July. This anthelmintic treatment significantly lowered egg excretion to EPG values lower than 30 in ewes and 50 or 60, respectively, in <span class="hlt">lambs</span>. Later, during the summer and autumn months, a mild rise of egg counts was found in <span class="hlt">lambs</span>. These maxima were liquidated anthelmintis treatment in both herds in late autumn months and it also lowered helminth infections to minimum during winter months (EPG values lower than 50). The excretion of Moniezia spp. eggs had the same dynamics as that gastrointestinal nematodes. Values of <span class="hlt">lamb</span> infection prevalence reached 21% in herd No. 1 and 29% in herd No. 2. Anthelmintic treatment during July controlled cestode findings in <span class="hlt">lambs</span>. Albendazol (Vermitan susp. 2.5%), dosed 5 mg/kg of body weight, proved highly effective in the control of gastrointestinal nematodes and Moniezia spp. cestodes. PMID:9182393</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23731948','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23731948"><span id="translatedtitle">Classification of flaw severity using pattern recognition for guided <span class="hlt">wave</span>-based structural health monitoring.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miller, Corey A; Hinders, Mark K</p> <p>2014-01-01</p> <p>In this paper, the authors present a formal classification routine to characterize flaw severity in an aircraft-grade aluminum plate using <span class="hlt">Lamb</span> <span class="hlt">waves</span>. A rounded rectangle flat-bottom hole is incrementally introduced into the plate, and at each depth multi-mode <span class="hlt">Lamb</span> <span class="hlt">wave</span> signals are collected to study the changes in received signal due to mode conversion and scattering from the flaw. <span class="hlt">Lamb</span> <span class="hlt">wave</span> tomography reconstructions are used to locate and size the flaw at each depth, however information about the severity of the flaw is obscured when the flaw becomes severe enough that scattering effects dominate. The dynamic wavelet fingerprint is then used to extract features from the raw <span class="hlt">Lamb</span> <span class="hlt">wave</span> signals, and supervised pattern classification techniques are used to identify flaw severity with up to 80.7% accuracy for a training set and up to 51.7% accuracy on a series of validation data sets extracted from independent plate samples. PMID:23731948</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OptEn..55a1006A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OptEn..55a1006A"><span id="translatedtitle">Detection and quantification of delamination in laminated plates from the phase of appropriate guided <span class="hlt">wave</span> modes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amjad, Umar; Yadav, Susheel Kumar; Kundu, Tribikram</p> <p>2016-01-01</p> <p>Applicability of specific <span class="hlt">Lamb</span> <span class="hlt">wave</span> modes for delamination detection and quantification in a laminated aluminum plate is investigated. The <span class="hlt">Lamb</span> modes were generated in the plate using a broadband piezoelectric transducer structured with a rigid electrode. Appropriate excitation frequencies and modes for inspection were selected from theoretical dispersion curves. Sensitivity of antisymmetric and symmetric modes for delamination detection and quantification has been investigated using the Hilbert-Huang transform. The mode conversion phenomenon of <span class="hlt">Lamb</span> <span class="hlt">waves</span> during progressive delamination is observed. The antisymmetric mode is found to be more reliable for delamination detection and quantification. In this investigation, the changes in the phase of guided <span class="hlt">Lamb</span> <span class="hlt">wave</span> modes are related to the degree of delamination, unlike other studies, where mostly the attenuation of the propagating <span class="hlt">waves</span> has been related to the extent of the internal damage, such as cracks and corrosions. Appropriate features for delamination detection and quantification are extracted from the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/565556','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/565556"><span id="translatedtitle">A rigid <span class="hlt">lamb</span> syndrome in sheep in Rhodesia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rudert, C P; Lawrence, J A; Foggin, C; Barlow, R M</p> <p>1978-04-29</p> <p>A syndrome characterised by the birth of <span class="hlt">lambs</span> with varying degrees of rigidity of the limbs and spine has been encountered on several occasions in Rhodesia. Outbreaks have occurred in autumn-born <span class="hlt">lambs</span> from Dorper ewes grazing heavily fertilised Star grass cv No 2 (Cynodon aethiopicus) pastures. The condition appears to be exacerbated by the application of sulphur to the pasture and is partly prevented by the administration of selenium and vitamin E to the ewes before <span class="hlt">lambing</span>. The aetiology is unknown. PMID:565556</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/338673','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/338673"><span id="translatedtitle">Fracture channel <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nihei, K.T.; Yi, W.; Myer, L.R.; Cook, N.G.; Schoenberg, M.</p> <p>1999-03-01</p> <p>The properties of guided <span class="hlt">waves</span> which propagate between two parallel fractures are examined. Plane <span class="hlt">wave</span> analysis is used to obtain a dispersion equation for the velocities of fracture channel <span class="hlt">waves</span>. Analysis of this equation demonstrates that parallel fractures form an elastic waveguide that supports two symmetric and two antisymmetric dispersive Rayleigh channel <span class="hlt">waves</span>, each with particle motions and velocities that are sensitive to the normal and tangential stiffnesses of the fractures. These fracture channel <span class="hlt">waves</span> degenerate to shear <span class="hlt">waves</span> when the fracture stiffnesses are large, to Rayleigh <span class="hlt">waves</span> and Rayleigh-<span class="hlt">Lamb</span> plate <span class="hlt">waves</span> when the fracture stiffnesses are low, and to fracture interface <span class="hlt">waves</span> when the fractures are either very closely spaced or widely separated. For intermediate fracture stiffnesses typical of fractured rock masses, fracture channel <span class="hlt">waves</span> are dispersive and exhibit moderate to strong localization of guided <span class="hlt">wave</span> energy between the fractures. The existence of these <span class="hlt">waves</span> is examined using laboratory acoustic measurements on a fractured marble plate. This experiment confirms the distinct particle motion of the fundamental antisymmetric fracture channel <span class="hlt">wave</span> (A{sub 0} mode) and demonstrates the ease with which a fracture channel <span class="hlt">wave</span> can be generated and detected. {copyright} 1999 American Geophysical Union</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20060042044&hterms=technology+transfer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtechnology%2Btransfer','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20060042044&hterms=technology+transfer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtechnology%2Btransfer"><span id="translatedtitle">Technology Transfer of Plate <span class="hlt">Wave</span> NDE to Ultrasonic Rotary Actuation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bar-Cohen, Y.</p> <p>1995-01-01</p> <p>Plate <span class="hlt">waves</span> have been the subject of NDE research and applications. These <span class="hlt">waves</span>, also known as guided <span class="hlt">waves</span> of <span class="hlt">Lamb</span> <span class="hlt">waves</span>, are formed in two distinct modes--symmetric and antisymmetric --depending on their vibration characteristics in relation to the plate geometry. Experiments have corroborated the predictions for various plate <span class="hlt">wave</span> modes, allowing the elastic properties of composite materials and adhesive bonded joints to be determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930068778&hterms=wave+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dwave%2Benergy','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930068778&hterms=wave+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dwave%2Benergy"><span id="translatedtitle">Effect of stress on energy flux deviation of ultrasonic <span class="hlt">waves</span> in GR/EP composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prosser, William H.; Kriz, R. D.; Fitting, Dale W.</p> <p>1990-01-01</p> <p>Ultrasonic <span class="hlt">waves</span> suffer energy flux deviation in graphite/epoxy because of the large anisotropy. The angle of deviation is a function of the elastic coefficients. For nonlinear solids, these coefficients and thus the angle of deviation is a function of stress. <span class="hlt">Acoustoelastic</span> theory was used to model the effect of stress on flux deviation for unidirectional T300/5208 using previously measured elastic coefficients. Computations were made for uniaxial stress along the x3 axis (fiber axis) and the x1 for <span class="hlt">waves</span> propagating in the x1x3 plane. These results predict a shift as large as three degrees for the quasi-transverse <span class="hlt">wave</span>. The shift in energy flux offers a new nondestructive technique of evaluating stress in composites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21509932','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21509932"><span id="translatedtitle"><span class="hlt">Lamb</span> shift for static atoms outside a Schwarzschild black hole</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhou Wenting; Yu Hongwei</p> <p>2010-11-15</p> <p>We study, by separately calculating the contributions of vacuum fluctuations and radiation reaction to the atomic energy level shift, the <span class="hlt">Lamb</span> shift of a static two-level atom interacting with real massless scalar fields in the Boulware, Unruh, and Hartle-Hawking vacuums outside a Schwarzschild black hole. We find that in the Boulware vacuum, the <span class="hlt">Lamb</span> shift gets a correction arising as a result of the backscattering of vacuum field modes off the space-time curvature, which is reminiscent of the correction to the <span class="hlt">Lamb</span> shift induced by the presence of cavities. However, when the Unruh and Hartle-Hawking vacua are concerned, our results show that the <span class="hlt">Lamb</span> shift behaves as if the atom were irradiated by a thermal radiation or immersed in a thermal bath at the Hawking temperature, depending on whether the scalar field is in the Unruh or the Hartle-Hawking vacuum. Remarkably, the thermal radiation is always backscattered by the space-time geometry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec59-301.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec59-301.pdf"><span id="translatedtitle">7 CFR 59.301 - Mandatory Daily Reporting for <span class="hlt">Lambs</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... were of a quality grade of Choice or better; (7) Any premiums or discounts associated with weight, quality grade, yield grade, or any type of purchase; (8) <span class="hlt">Lamb</span> state of origin; (9) The pelt type; and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec59-301.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec59-301.pdf"><span id="translatedtitle">7 CFR 59.301 - Mandatory Daily Reporting for <span class="hlt">Lambs</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... were of a quality grade of Choice or better; (7) Any premiums or discounts associated with weight, quality grade, yield grade, or any type of purchase; (8) <span class="hlt">Lamb</span> state of origin; (9) The pelt type; and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26882113','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26882113"><span id="translatedtitle">Farmer and Public Attitudes Toward <span class="hlt">Lamb</span> Finishing Systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Coleman, Grahame; Jongman, Ellen; Greenfield, L; Hemsworth, Paul</p> <p>2016-01-01</p> <p>To develop research and policy on the welfare of <span class="hlt">lambs</span> in intensive finishing systems, it is important to understand public and sheep farmers' attitudes. The aim of this research was to identify and compare farmer and community attitudes relevant to the intensification of <span class="hlt">lamb</span> finishing. The majority of respondents in the community sample expressed concern about all listed welfare issues, but particularly about feedlotting of <span class="hlt">lambs</span> and the associated confinement. These attitudes correlated with community views on the importance of welfare issues including social contact and freedom to roam. Farmers expressed much lower levels of concern than did the general public except with regard to the health of <span class="hlt">lambs</span>, disease control, access to shade, and lack of access to clean water. PMID:26882113</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2925182','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2925182"><span id="translatedtitle">Eyeblink Classical Conditioning in the Preweanling <span class="hlt">Lamb</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Johnson, Timothy B.; Stanton, Mark E.; Goodlett, Charles R.; Cudd, Timothy A.</p> <p>2010-01-01</p> <p>Classical conditioning of eyeblink responses has been one of the most important models for studying the neurobiology of learning, with many comparative, ontogenetic, and clinical applications. The current study reports the development of procedures to conduct eyeblink conditioning in preweanling <span class="hlt">lambs</span> and demonstrates successful conditioning using these procedures. These methods will permit application of eyeblink conditioning procedures in the analysis of functional correlates of cerebellar damage in a sheep model of fetal alcohol spectrum disorders, which has significant advantages over more common laboratory rodent models. Because sheep have been widely used for studies of pathogenesis and mechanisms of injury with many different prenatal or perinatal physiological insults, eyeblink conditioning can provide a well-studied method to assess postnatal behavioral outcomes, which heretofore have not typically been pursued with ovine models of developmental insults. PMID:18513143</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21439548','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21439548"><span id="translatedtitle">Cooperative <span class="hlt">Lamb</span> shift in an ellipsoid</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Friedberg, Richard; Manassah, Jamal T.</p> <p>2010-06-15</p> <p>It has been long known that the global cooperative <span class="hlt">Lamb</span> shift (CLS) in a large superradiantly emitting sphere has equal magnitude but opposite sign to that of a slab. This result was obtained from QED in 1973 for samples of uniform density. This change of sign holds as well for a Gaussian density distribution. The same result is also obtained for either density in the scalar simplification of QED now in frequent use. Since the CLS must be a continuous function of shape, and the slab resembles a limiting case of oblate ellipsoid, there must be some shape of ellipsoid for which the CLS is zero. We report a calculation of CLS for a Gaussian distribution of general azimuthally symmetric ellipsoidal shape. The CLS is found to vanish when the mean square radius is twice as great transversely as longitudinally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JSV...333..541N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JSV...333..541N"><span id="translatedtitle">Nonlinear <span class="hlt">wave</span> propagation in constrained solids subjected to thermal loads</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nucera, Claudio; Lanza di Scalea, Francesco</p> <p>2014-01-01</p> <p>The classical mathematical treatment governing nonlinear <span class="hlt">wave</span> propagation in solids relies on finite strain theory. In this scenario, a system of nonlinear partial differential equations can be derived to mathematically describe nonlinear phenomena such as <span class="hlt">acoustoelasticity</span> (<span class="hlt">wave</span> speed dependency on quasi-static stress), <span class="hlt">wave</span> interaction, <span class="hlt">wave</span> distortion, and higher-harmonic generation. The present work expands the topic of nonlinear <span class="hlt">wave</span> propagation to the case of a constrained solid subjected to thermal loads. The origin of nonlinear effects in this case is explained on the basis of the anharmonicity of interatomic potentials, and the absorption of the potential energy corresponding to the (prevented) thermal expansion. Such "residual" energy is, at least, cubic as a function of strain, hence leading to a nonlinear <span class="hlt">wave</span> equation and higher-harmonic generation. Closed-form solutions are given for the longitudinal <span class="hlt">wave</span> speed and the second-harmonic nonlinear parameter as a function of interatomic potential parameters and temperature increase. The model predicts a decrease in longitudinal <span class="hlt">wave</span> speed and a corresponding increase in nonlinear parameter with increasing temperature, as a result of the thermal stresses caused by the prevented thermal expansion of the solid. Experimental measurements of the ultrasonic nonlinear parameter on a steel block under constrained thermal expansion confirm this trend. These results suggest the potential of a nonlinear ultrasonic measurement to quantify thermal stresses from prevented thermal expansion. This knowledge can be extremely useful to prevent thermal buckling of various structures, such as continuous-welded rails in hot weather.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1581..690C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1581..690C"><span id="translatedtitle">Rayleigh <span class="hlt">wave</span> interaction and mode conversion in a delamination</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chakrapani, Sunil Kishore; Dayal, Vinay; Dunt, Jamie</p> <p>2014-02-01</p> <p>The interaction of Rayleigh <span class="hlt">waves</span> with a delamination in a fiber reinforced composite plate was analyzed in the present work. Rayleigh <span class="hlt">waves</span> interacting with delamination, mode convert into <span class="hlt">Lamb</span> <span class="hlt">waves</span> in the delamination zone. These guided <span class="hlt">Lamb</span> modes have the capability to mode convert back into Rayleigh modes when they interact with the edge of the delamination. Unidirectional glass/epoxy laminate with delamination of known size was fabricated and tested using air-coupled ultrasonics. Finite element models were developed to understand the various mode conversions. Experimental and numerical A-Scans, mode velocities were used to identify each mode. A good correlation between experimental and numerical results was observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014FlDyR..46f1417L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014FlDyR..46f1417L"><span id="translatedtitle">A dynamic counterpart of <span class="hlt">Lamb</span> vector in viscous compressible aerodynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, L. Q.; Wu, J. Z.; Shi, Y. P.; Zhu, J. Y.</p> <p>2014-12-01</p> <p>The <span class="hlt">Lamb</span> vector is known to play a key role in incompressible fluid dynamics and vortex dynamics. In particular, in low-speed steady aerodynamics it is solely responsible for the total force acting on a moving body, known as the vortex force, with the classic two-dimensional (exact) Kutta-Joukowski theorem and three-dimensional (linearized) lifting-line theory as the most famous special applications. In this paper we identify an innovative dynamic counterpart of the <span class="hlt">Lamb</span> vector in viscous compressible aerodynamics, which we call the compressible <span class="hlt">Lamb</span> vector. Mathematically, we present a theorem on the dynamic far-field decay law of the vorticity and dilatation fields, and thereby prove that the generalized <span class="hlt">Lamb</span> vector enjoys exactly the same integral properties as the <span class="hlt">Lamb</span> vector does in incompressible flow, and hence the vortex-force theory can be generalized to compressible flow with exactly the same general formulation. Moreover, for steady flow of polytropic gas, we show that physically the force exerted on a moving body by the gas consists of a transverse force produced by the original <span class="hlt">Lamb</span> vector and a new longitudinal force that reflects the effects of compression and irreversible thermodynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6994135','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6994135"><span id="translatedtitle">Cerebral blood flow autoregulation during intracranial hypertension in hypoxic <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Borel, C.O.; Backofen, J.E.; Koehler, R.C.; Jones, M.D. Jr.; Traystman, R.J. )</p> <p>1987-12-01</p> <p>The authors tested the hypothesis that hypoxic hypoxia interferes with cerebral blood flow (CBF) autoregulation when intracranial pressure (ICP) is elevated in pentobarbital-anesthetized <span class="hlt">lambs</span> (3 to 9 days old). Cerebral perfusion pressure (CPP) was lowered stepwise from 73 to 23 mmHg in eight normoxic <span class="hlt">lambs</span> and from 65 to 31 mmHg in eight other hypoxic <span class="hlt">lambs</span> by ventricular infusion of artificial cerebrospinal fluid. In normoxic <span class="hlt">lambs</span>, CBF measured by microspheres labeled with six different radioisotopes was not significantly changed over this range of CPP. In animals made hypoxic, base-line CBF was twice that of normoxic <span class="hlt">lambs</span>. CBF was unchanged as CPP was reduced to 31 mmHg. Lower levels of CPP were not attained because a pressor response occurred with further elevations of ICP. No regional decrements in blood flow to cortical arterial watershed areas or to more caudal regions, such as cerebellum, brain stem, or thalamus, were detected with elevated ICP. Cerebral O{sub 2} uptake was similar in both groups and did not decrease when CPP was reduced. These results demonstrate that normoxic <span class="hlt">lambs</span> have a considerable capacity for effective autoregulation of CBF when ICP is elevated. Moreover, cerebral vasodilation in response to a level of hypoxia approximating that normally seen prenatally does not abolish CBF autoregulation when ICP is elevated during the first postnatal week.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMMR33A2448B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMMR33A2448B"><span id="translatedtitle">Probing an S-<span class="hlt">wave</span> with a P-<span class="hlt">wave</span>: experimental developments for understanding rock nonlinearities</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, S. R.; Gallot, T.; Malcolm, A. E.; Fehler, M. C.; Szabo, T.; Burns, D.; Zhu, Z.</p> <p>2012-12-01</p> <p>The nonlinear characterization of rocks is a research topic applicable to several geophysical problems such as erthquake source physics, reservoir fracturing processes or imaging. Recently, dynamic methods have been shown to reveal new information about the nonlinear response of materials. Existing methods generally rely on vibrating a sample at a fixed resonant frequency to create a low frequency strain (the pump). During a cycle of the pump, the nonlinear response of the material is measured via a high frequency <span class="hlt">wave</span> (the probe). In a similar method, the standing <span class="hlt">wave</span> is replaced by a pulsed <span class="hlt">wave</span>. This method extends the so-called Dynamic <span class="hlt">Acousto-Elastic</span> Testing (DAET) to semi-infinite media and allows for frequency scans of the non linear response. We have performed laboratory experiments in rocks (berea sandstones) to explore the possibility of using such method for Earth imaging. For the pump, we use a shear <span class="hlt">wave</span> with frequencies in the tens of kHz and the probe is a compressional pulse in the hundreds of kHz range. In this configuration, we are interested in the delay of the probe caused by the pump via a nonlinear interaction. The results highlight a fast rectification effect and a slow weakening effect, respectively related to classical non linearities and conditioning of the material. The dynamics of the conditioning can be studied with this pulsed method. Using a shear <span class="hlt">wave</span> pump also gives us the opportunity to study the effect of the relative orientation of the pump.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011SPIE.7984E..02R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SPIE.7984E..02R"><span id="translatedtitle"><span class="hlt">Wave</span> propagation in isogrid structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reynolds, Whitney D.; Doyle, Derek; Arritt, Brandon</p> <p>2011-04-01</p> <p>This work focuses on an analysis of <span class="hlt">wave</span> propagation in isogrid structures as it relates to Structural Health Monitoring (SHM) methods. Assembly, integration, and testing (AI&T) of satellite structures in preparation for launch includes significant time for testing and reworking any issues that may arise. SHM methods are being investigated as a means to validate the structure during assembly and truncate the number of tests needed to qualify the structure for the launch environment. The most promising of these SHM methods uses an active <span class="hlt">wave</span>-based method in which an actuator propagates a <span class="hlt">Lamb</span> <span class="hlt">wave</span> through the structure; the <span class="hlt">Lamb</span> <span class="hlt">wave</span> is then received by a sensor and evaluated over time to detect structural changes. To date this method has proven effective in locating structural defects in a complex satellite panel; however, the attributes associated with the first <span class="hlt">wave</span> arrival change significantly as the <span class="hlt">wave</span> travels through ribs and joining features. Previous studies have been conducted in simplified ribbed structures, giving initial insight into the complex <span class="hlt">wave</span> propagation phenomena. In this work, the study has been extended numerically to the isogrid plate case. <span class="hlt">Wave</span> propagation was modeled using commercial finite element analysis software. The results of the analyses offer further insight into the complexities of <span class="hlt">wave</span> propagation in isogrid structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18479584','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18479584"><span id="translatedtitle">Effects of the absence of protozoa from birth or from weaning on the growth and methane production of <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hegarty, R S; Bird, S H; Vanselow, B A; Woodgate, R</p> <p>2008-12-01</p> <p>Merino ewes (n 108) joined to a single sire were allocated into three flocks, with ewes in one flock being chemically defaunated in the second month of gestation. Single <span class="hlt">lambs</span> born to defaunated ewes (BF <span class="hlt">lambs</span>) were heavier at birth and at weaning than <span class="hlt">lambs</span> born to faunated ewes (F <span class="hlt">lambs</span>). After weaning, all BF and F <span class="hlt">lambs</span> were individually housed then half of the F <span class="hlt">lambs</span> were chemically defaunated (DF <span class="hlt">lambs</span>). In trial 1, BF, DF and F <span class="hlt">lambs</span> were offered a concentrate-based diet containing either 14 or 19 % protein for a 10-week period. Wool growth rate of BF <span class="hlt">lambs</span> was 10 % higher than that of DF or F <span class="hlt">lambs</span> and was increased 9 % by the high-protein diet. While there was no main effect of protozoa treatment on enteric methane production, there was an interaction between protozoa treatment and diet for methane production. BF and DF <span class="hlt">lambs</span> produced more methane than F <span class="hlt">lambs</span> when fed the low-protein diet but when fed the high-protein diet, emissions were less than (BF <span class="hlt">lambs</span>) or not different from (DF <span class="hlt">lambs</span>) emissions from F <span class="hlt">lambs</span>. In trial 2, <span class="hlt">lambs</span> were offered 800 g roughage per d and, again, methane production was not affected by the presence of protozoa in the rumen. The data indicate that while <span class="hlt">lambs</span> without rumen protozoa have greater protein availability than do faunated ruminants, there is no main effect of rumen protozoa on enteric methane production by <span class="hlt">lambs</span> fed either a concentrate or roughage diet. PMID:18479584</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25030481','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25030481"><span id="translatedtitle">Correlations among ultrasonographic and microscopic characteristics of prepubescent ram <span class="hlt">lamb</span> testes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Giffin, Jennifer L; Bartlewski, Pawel M; Hahnel, Ann C</p> <p>2014-12-01</p> <p>The onset of spermatogenesis during prepubertal development is accompanied by dynamic changes in testicular microstructure. Computer-assisted analysis of scrotal ultrasonograms may allow us to track these changes in a noninvasive manner; however, the echotextural characteristics of different histomorphological variables remain unclear. Hence the objective of this study was to compare echotextural and microscopic attributes of the testis over the first <span class="hlt">wave</span> of spermatogenesis in prepubescent ram <span class="hlt">lambs</span>. Bi-weekly ultrasound examinations and weekly testicular biopsies were carried out in 22 ram <span class="hlt">lambs</span> from 9.5-10 weeks of age or the attainment of 15 cm(3) in testicular volume, respectively, to the first detection of elongated spermatids (ESt). Testicular echogenicity was highly variable with age; however, after the alignment of data to the first detection of ESt, there was an initial increase followed by a decline, corresponding to the mitotic and postmitotic phases of spermatogenesis in prepubescent ram <span class="hlt">lambs</span>. Testicular echotextural attributes (mean numerical pixel values and pixel heterogeneity) correlated with seminiferous tubule (ST) diameter, the number of degenerating cells/ST cross-section (XS), and the number of ubiquitin C-terminal hydrolase L-1 (a marker for prespermatogonia and undifferentiated spermatogonia) staining cells/ST XS during the mitotic and postmitotic phases. Additionally, in the postmitotic phase, significant correlations were recorded between the quantitative echotextural characteristics and ST cell density, nuclear:ST area and percentages of STs with different spermatogenic cells as the most mature germ cell type present. These results indicate that ram testes exhibit distinctive echotextural characteristics during the mitotic and postmitotic phases of germ cell differentiation. It is concluded that scrotal ultrasonography in conjunction with computerized image analysis holds potential as a noninvasive alternative to testicular biopsy in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008EM%26P..102..345R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008EM%26P..102..345R&link_type=ABSTRACT"><span id="translatedtitle">Acoustic-Gravity <span class="hlt">Waves</span> from Bolide Sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Revelle, Douglas O.</p> <p>2008-06-01</p> <p>We have developed a new approach to modeling the acoustic-gravity <span class="hlt">wave</span> (AGW) radiation from bolide sources. This first effort involves entry modeling of bolide sources that have available satellite data through procedures developed in ReVelle (Earth Moon Planets 95, 441-476, 2004a; in: A. Milani, G. Valsecchi, D. Vokrouhlicky (eds) NEO Fireball Diversity: Energetics-based Entry Modeling and Analysis Techniques, Near-earth Objects: Our Celestial Neighbors (IAU S236), 2007b). Results from the entry modeling are directly coupled to AGW production through line source blast <span class="hlt">wave</span> theory for the initial <span class="hlt">wave</span> amplitude and period at x=10 (at 10 blast <span class="hlt">wave</span> radii and perpendicular to the trajectory). The second effort involves the prediction of the formation and or dominance of the propagation of the atmospheric <span class="hlt">Lamb</span>, edge-<span class="hlt">wave</span> composite mode in a viscous fluid (Pierce, J. Acoust. Soc. Amer. 35, 1798-1807, 1963) as a function of the source energy, horizontal range and source altitude using the <span class="hlt">Lamb</span> <span class="hlt">wave</span> frequency that was deduced directly during the entry modeling and that is used as a surrogate for the source energy. We have also determined that <span class="hlt">Lamb</span> <span class="hlt">wave</span> production by bolides at close range decreases dramatically as either the source energy decreases or the source altitude increases. Finally using procedures in Gill ( Atmospheric-Ocean Dynamics, 1982) and in Tolstoy ( <span class="hlt">Wave</span> Propagation, 1973), we have analyzed two simple dispersion relationships and have calculated the expected dispersion for the <span class="hlt">Lamb</span> edge-<span class="hlt">wave</span> mode and for the excited, propagating internal acoustic <span class="hlt">waves</span>. Finally, we have used the above formalism to fully evaluate these techniques for four large bolides, namely: the Tunguska bolide of June 30, 1908; the Revelstoke bolide of March 31, 1965; the Crete bolide of June 6, 2002 and the Antarctic bolide of September 3, 2004. Due to page limitations, we will only present results in detail for the Revelstoke bolide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22021813','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22021813"><span id="translatedtitle">Index selection in terminal sires improves early <span class="hlt">lamb</span> growth.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Márquez, G C; Haresign, W; Davies, M H; Emmans, G C; Roehe, R; Bünger, L; Simm, G; Lewis, R M</p> <p>2012-01-01</p> <p>The use of terminal sires (TS) for crossbreeding is integral to the UK sheep industry where approximately 71% of market <span class="hlt">lambs</span> are sired by TS rams. Early growth of these crossbred <span class="hlt">lambs</span> affects profitability. The objectives of this study were i) to evaluate the effectiveness of index selection among TS on BW and ADG of their crossbred offspring; and ii) to compare the efficacy of that selection within TS breeds. The most widely used TS breeds in the United Kingdom are Charollais, Suffolk, and Texel. These participated in sire referencing schemes in which they were evaluated on a lean growth index designed to increase carcass lean weight at a given age. From 1999 to 2002, approximately 15 high and 15 low lean growth index rams per breed (93 in total, differing in index on average by 4.6 SD) were selected from within their sire referencing schemes and mated to Welsh and Scottish Mule ewes. Their crossbred offspring were reared commercially on 3 experimental farms in England, Scotland, and Wales. A total of 6,515 <span class="hlt">lambs</span> were born between 2000 and 2003. <span class="hlt">Lambs</span> were weighed at birth (BWT), 5 wk (5WT), and 10 wk (10WT), and their ADG from birth to 10 wk was calculated. <span class="hlt">Lambs</span> sired by high index rams were on average, across breeds, heavier at all ages (P < 0.01) with 0.07 ± 0.03, 0.3 ± 0.1, and 0.4 ± 0.1 kg greater BWT, 5WT, and 10WT, respectively. Their ADG was 5.1 ± 1.9 g/d greater than low-index-sired <span class="hlt">lambs</span> (P < 0.01). Suffolk-sired <span class="hlt">lambs</span> were on average heavier at all ages, with greater ADG, whereas Charollais-sired <span class="hlt">lambs</span> were lightest with smallest ADG. Overall, there was no significant interaction between sire index and sire breed (P > 0.10). Within Suffolk-sired <span class="hlt">lambs</span>, there was little difference between high and low index sires for the traits studied (P > 0.3). High and low index Charollais-sired <span class="hlt">lambs</span> differed in BWT (0.09 ± 0.04 kg) and 5WT (0.3 ± 0.1 kg), and Texel-sired <span class="hlt">lambs</span> differed in 5WT (0.5 ± 0.1 kg), 10WT (0.9 ± 0.2 kg), and ADG (10.2 ± 3.3 g</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22062140','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22062140"><span id="translatedtitle">Knife and impact cutting of <span class="hlt">lamb</span> bone.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>King, M J</p> <p>1999-05-01</p> <p>The forces and hence fracture energies required to cut bone are presented in this paper and the merits of cutting with a high speed blade are considered. A plain knife blade was used to cut cancellous and compact <span class="hlt">lamb</span> bone using three different methods. A microtome was used to produce a range of cut thicknesses which enabled the fracture energy to be separated into friction, surface fracture and plastic deformation energies. A tensile test machine was used to produce thicker off-cuts so that the energy required to cut through full sections of bone could be determined. A high speed rail gun was used to cut at speeds up to 130 m/s. The energy required to cut bone did not change with blade speed. However, the energies measured during the cutting varied over a wide range. In situations in which the surface of the cut bone exhibited a very uneven surface high energy was required, whereas when the resulting cut surface was planar the cutting energy was low. A light weight blade which impacts the bone at high speed will transmit a small impulse to the carcass which may be absorbed without transmitting strain to the muscle/connective tissue. This may allow the development of a high speed knife which will cut bone without excessively damaging the meat surrounding the cut. PMID:22062140</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/10709742','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/10709742"><span id="translatedtitle">Lung injury and surfactant metabolism after hyperventilation of premature <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ikegami, M; Kallapur, S; Michna, J; Jobe, A H</p> <p>2000-03-01</p> <p>We asked whether lung injury and surfactant metabolism differed in preterm <span class="hlt">lambs</span> after a 1-h period of hyperventilation to P(CO2) values of 25-30 mm Hg. The <span class="hlt">lambs</span> then were surfactant treated and conventionally ventilated (CV) or high-frequency oscillatory ventilated (HFOV) for an additional 1 or 8 h. The results were compared with <span class="hlt">lambs</span> that were not hyperventilated or surfactant treated but were ventilated with CV or HFOV. The 1-h hyperventilation resulted in increased alveolar protein, increased recovery of intravascular [131I]albumin in the lungs, and an increase in tumor necrosis factor-alpha mRNA. There were no differences between CV or HFOV in alveolar or total lung recoveries of saturated phosphatidylcholine (Sat PC), tracer doses of [14C]Sat PC and [125I]surfactant protein-B, or in percent Sat PC in large aggregate surfactant in surfactant-treated <span class="hlt">lambs</span>. The <span class="hlt">lambs</span> not hyperventilated or treated with surfactant had lower large aggregate pools and lower recoveries of [14C]Sat PC and [125I]surfactant protein-B in total lungs than for the surfactant-treated lungs, but there were no differences between the CV and HFOV groups. Hyperventilation followed by surfactant treatment resulted in a mild injury, but the subsequent use of CV or HFOV did not result in differences in surfactant metabolism. PMID:10709742</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1978297','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1978297"><span id="translatedtitle">Diprosopus with multiple craniofacial, musculoskeletal, and cardiac defects in a purebred Suffolk <span class="hlt">lamb</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kerr, Nancy J.</p> <p>2007-01-01</p> <p>A stillborn Suffolk ewe <span class="hlt">lamb</span> with 2 heads was found to have tarsal arthrogryposis, kypholordosis, craniorachischisis totalis, cheiloschisis, palatoschisis, deviation of the right maxilla, prognathia, patent ductus arteriosus, 3 ventricular septal defects, and 4 great vessels. The <span class="hlt">lamb</span> was born twin to a normal <span class="hlt">lamb</span>. No definitive etiology was established. PMID:17987971</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol15/pdf/CFR-2010-title7-vol15-sec4279-175.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol15/pdf/CFR-2010-title7-vol15-sec4279-175.pdf"><span id="translatedtitle">7 CFR 4279.175 - Domestic <span class="hlt">lamb</span> industry adjustment assistance program set aside.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... National Office to fund loans to <span class="hlt">lamb</span> processors for real estate purchases and improvements; working... 7 Agriculture 15 2010-01-01 2010-01-01 false Domestic <span class="hlt">lamb</span> industry adjustment assistance program... GUARANTEED LOANMAKING Business and Industry Loans § 4279.175 Domestic <span class="hlt">lamb</span> industry adjustment...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/2775061','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/2775061"><span id="translatedtitle">The extent and cause of perinatal <span class="hlt">lamb</span> mortality in 3 flocks of Merino sheep.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jordan, D J; Le Feuvre, A S</p> <p>1989-07-01</p> <p>Autopsies were performed on <span class="hlt">lamb</span> carcases from 2 groups of Merino ewes <span class="hlt">lambing</span> in paddocks in spring 1978 and from 1 group <span class="hlt">lambing</span> in pens in 1980 in southwest Queensland. These showed that the main causes of death were starvation due to failure of the <span class="hlt">lamb</span> to obtain milk, problems at parturition causing death during or shortly after birth and, in some cases, predation. The majority of <span class="hlt">lambs</span> died within 1 week of birth with the highest mortalities occurring in the lighter <span class="hlt">lambs</span>. In the pen study, mean birth weight of <span class="hlt">lambs</span> that died was 3.0 (s.d. = +/- 0.5) kg. The mean daily weight loss of <span class="hlt">lambs</span> that died of starvation in the pens was 0.22 kg and the mean loss to autopsy was 0.35 kg. In the pen study, there were more <span class="hlt">lamb</span> deaths, deaths from starvation, mismothering and desertion in each of 2 groups fed a below maintenance ration than in an above maintenance group. More <span class="hlt">lambs</span> died and more <span class="hlt">lamb</span> deaths were due to starvation in a group with unsound udders than in a sound udder group. The results are similar to those found by workers investigating perinatal <span class="hlt">lamb</span> mortality in other areas. Their significance is discussed in relation to Merino sheep flocks in southwestern Queensland. PMID:2775061</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=233595','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=233595"><span id="translatedtitle">Impact of rotational grazing on management of gastrointestinal nematodes in weaned <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Gastrointestinal nematode (GIN) control for ‘natural’ or organic <span class="hlt">lamb</span> production is needed, especially where Haemonchus contortus is prevalent. The objective was to determine the impact of rotational grazing on GIN infection of weaned <span class="hlt">lambs</span>. In year 1, naturally infected Katahdin <span class="hlt">lambs</span> (120 days of ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/9413734','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/9413734"><span id="translatedtitle">Influence of feeding and ambient temperature on thermoregulation in newborn <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Clarke, L; Heasman, L; Firth, K; Symonds, M E</p> <p>1997-11-01</p> <p>This study examined the effect of ambient temperature and feeding on brown adipose tissue (BAT) function and thermoregulation in <span class="hlt">lambs</span> born either vaginally at term or by Caesarean section close to term. Immediately after birth <span class="hlt">lambs</span> were placed in a warm (30 degrees C) or cool (15 degrees C) ambient temperature and measurements of colonic temperature and heat production recorded for 6 h. <span class="hlt">Lambs</span> were fed 50 ml of colostrum when 5 h old. The amount of uncoupling protein and level of guanosine 5'diphosphate (GDP) binding in BAT was higher in vaginally delivered <span class="hlt">lambs</span> than in <span class="hlt">lambs</span> delivered by Caesarean section. For each delivery group, GDP binding was greater in <span class="hlt">lambs</span> maintained at 30 degrees C than in <span class="hlt">lambs</span> maintained at 15 degrees C. O2 consumption, CO2 production and colonic temperature only increased after feeding in <span class="hlt">lambs</span> born by Caesarean section and maintained at 30 degrees C, a response that was accompanied by a decreased incidence of shivering. Irrespective of delivery temperature, plasma thyroid hormone concentrations and noradrenaline content of BAT were lower in <span class="hlt">lambs</span> born by Caesarean section than in those born vaginally. Plasma cortisol concentrations were higher in <span class="hlt">lambs</span> delivered by Caesarean section, as was adrenaline content of BAT in these <span class="hlt">lambs</span> maintained at 30 degrees C. It is concluded that the thermoregulatory response to feeding in terms of changes in both recruitment of shivering and colonic temperature were observed only in <span class="hlt">lambs</span> delivered by Caesarean section. PMID:9413734</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18238400','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18238400"><span id="translatedtitle">Generation and reception of ultrasonic guided <span class="hlt">waves</span> in composite plates using conformable piezoelectric transmitters and optical-fiber detectors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gachagan, A; Hayward, G; McNab, A; Reynolds, P; Pierce, S G; Philp, W R; Culshaw, B</p> <p>1999-01-01</p> <p>A condition monitoring nondestructive evaluation (NDE) system, combining the generation of ultrasonic <span class="hlt">Lamb</span> <span class="hlt">waves</span> in thin composite plates and their subsequent detection using an embedded optical fiber system is described. The acoustic source is of low profile with respect to the composite plate thickness, surface conformable, and able to efficiently launch a known <span class="hlt">Lamb</span> <span class="hlt">wave</span> mode, at operating frequencies between 100 and 500 kHz, over typical propagation distances of 100 to 500 mm. It incorporates both piezocomposite technology and interdigital design techniques to generate the fundamental symmetrical <span class="hlt">Lamb</span> <span class="hlt">wave</span> mode in both metallic and carbon-fiber composite plates. Linear systems and finite element modeling techniques have been used to evaluate the operation of the transducer structure, and this is supplemented by experimental verification of the simulated data. An optical fiber, either bonded to the surface or embedded across the length of the composite plate samples, is used to detect the propagating ultrasonic <span class="hlt">Lamb</span> <span class="hlt">waves</span>. Single mode silica fiber has been used in conjunction with a portable 633 nm Mach-Zehnder interferometer for signal demodulation and subsequent data acquisition. This hybrid system is shown to generate and detect the fundamental symmetrical <span class="hlt">Lamb</span> <span class="hlt">wave</span> (s(0)) in both carbon-fiber and glass-fiber reinforced composite plates. Importantly, the system signal-to-noise ratio (SNR) associated with the acoustic source compares favorably with s(0) <span class="hlt">Lamb</span> <span class="hlt">wave</span> generation using a conventional transducer and angled perspex wedge arrangement. PMID:18238400</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990049232&hterms=Method+analysis+Group&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMethod%2Banalysis%2BGroup','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990049232&hterms=Method+analysis+Group&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMethod%2Banalysis%2BGroup"><span id="translatedtitle">Time-Frequency Analysis of the Dispersion of <span class="hlt">Lamb</span> Modes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prosser, W. H.; Seale, Michael D.; Smith, Barry T.</p> <p>1999-01-01</p> <p>Accurate knowledge of the velocity dispersion of <span class="hlt">Lamb</span> modes is important for ultrasonic nondestructive evaluation methods used in detecting and locating flaws in thin plates and in determining their elastic stiffness coefficients. <span class="hlt">Lamb</span> mode dispersion is also important in the acoustic emission technique for accurately triangulating the location of emissions in thin plates. In this research, the ability to characterize <span class="hlt">Lamb</span> mode dispersion through a time-frequency analysis (the pseudo-Wigner-Ville distribution) was demonstrated. A major advantage of time-frequency methods is the ability to analyze acoustic signals containing multiple propagation modes, which overlap and superimpose in the time domain signal. By combining time-frequency analysis with a broadband acoustic excitation source, the dispersion of multiple <span class="hlt">Lamb</span> modes over a wide frequency range can be determined from as little as a single measurement. In addition, the technique provides a direct measurement of the group velocity dispersion. The technique was first demonstrated in the analysis of a simulated waveform in an aluminum plate in which the <span class="hlt">Lamb</span> mode dispersion was well known. Portions of the dispersion curves of the AO, A I , So, and S2 <span class="hlt">Lamb</span> modes were obtained from this one waveform. The technique was also applied for the analysis of experimental waveforms from a unidirectional graphite/epoxy composite plate. Measurements were made both along and perpendicular to the fiber direction. In this case, the signals contained only the lowest order symmetric and antisymmetric modes. A least squares fit of the results from several source to detector distances was used. Theoretical dispersion curves were calculated and are shown to be in good agreement with experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050042034','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050042034"><span id="translatedtitle">Time-Frequency Analysis of the Dispersion of <span class="hlt">Lamb</span> Modes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prosser, W. H.; Seale, Michael D.; Smith, Barry T.</p> <p>1999-01-01</p> <p>Accurate knowledge of the velocity dispersion of <span class="hlt">Lamb</span> modes is important for ultrasonic nondestructive evaluation methods used in detecting and locating flaws in thin plates and in determining their elastic stiffness coefficients. <span class="hlt">Lamb</span> mode dispersion is also important in the acoustic emission technique for accurately triangulating the location of emissions in thin plates. In this research, the ability to characterize <span class="hlt">Lamb</span> mode dispersion through a time-frequency analysis (the pseudo Wigner-Ville distribution) was demonstrated. A major advantage of time-frequency methods is the ability to analyze acoustic signals containing multiple propagation modes, which overlap and superimpose in the time domain signal. By combining time-frequency analysis with a broadband acoustic excitation source, the dispersion of multiple <span class="hlt">Lamb</span> modes over a wide frequency range can be determined from as little as a single measurement. In addition, the technique provides a direct measurement of the group velocity dispersion. The technique was first demonstrated in the analysis of a simulated waveform in an aluminum plate in which the <span class="hlt">Lamb</span> mode dispersion was well known. Portions of the dispersion curves of the A(sub 0), A(sub 1), S(sub 0), and S(sub 2)<span class="hlt">Lamb</span> modes were obtained from this one waveform. The technique was also applied for the analysis of experimental waveforms from a unidirectional graphite/epoxy composite plate. Measurements were made both along, and perpendicular to the fiber direction. In this case, the signals contained only the lowest order symmetric and antisymmetric modes. A least squares fit of the results from several source to detector distances was used. Theoretical dispersion curves were calculated and are shown to be in good agreement with experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1980IJBm...24..223S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1980IJBm...24..223S&link_type=ABSTRACT"><span id="translatedtitle">Parasitic gastro-enteritis in <span class="hlt">lambs</span> — A model for estimating the timing of the larval emergence peak</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Starr, J. R.; Thomas, R. J.</p> <p>1980-09-01</p> <p>The life history of the nematode parasites of domestic ruminants usually involves the development and survival of free-living stages on pasture. The pasture is, therefore, the site of deposition, development and transmission of nematode infection and meteorological factors affecting the pasture will affect the parasites. Recently Thomas and Starr (1978) discussed an empirical technique for forecasting the timing of the summer <span class="hlt">wave</span> of gastro-intestinal parasitism in North-East England in the <span class="hlt">lamb</span> crop using meteorological data and in particular estimates of the duration of “surface wetness”. This paper presents an attempt to model “surface wetness” and the temperature limitation to nematode development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23978840','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23978840"><span id="translatedtitle">Diagnostic exercise: hemolysis and sudden death in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Giannitti, F; Rioseco, M Macias; García, J P; Beingesser, J; Woods, L W; Puschner, B; Uzal, F A</p> <p>2014-05-01</p> <p>Within a 24-hour period, 7 out of 200 three- to four-week-old pastured Katahdin <span class="hlt">lambs</span> died after showing clinical signs of hemoglobinuria, red-tinged feces, weakness, and recumbency. One of the <span class="hlt">lambs</span> that was examined clinically before natural death also had abdominal pain, trembling, tachycardia, and severe anemia with a packed cell volume of 4%. Pathologic findings included icterus, hemoglobinuric nephrosis, dark red urine, pulmonary edema, hydrothorax, splenomegaly, and acute centrilobular to midzonal hepatocellular degeneration and necrosis with cholestasis. The differential diagnoses and diagnostic workup to achieve the diagnosis are briefly discussed. PMID:23978840</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6689598','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6689598"><span id="translatedtitle">The <span class="hlt">Lamb</span> shift in heliumlike uranium (U/sup 90 +/)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Munger, C.T. Jr.</p> <p>1987-01-01</p> <p>An experimental value of 70.4 (8.3) eV for the one-electron <span class="hlt">Lamb</span> shift in uranium is reported, in agreement with the theoretical value of 75.3 (0.4) eV. The <span class="hlt">Lamb</span> shift is extracted from a beam-foil time-of-flight measurement of the 54.4 (3.4) ps lifetime of the 1s 2p/sub 1/2/ /sup 3/P/sub 0/ state of heliumlike (two-electron) uranium. 18 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title16-vol1/pdf/CFR-2010-title16-vol1-sec301-8.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title16-vol1/pdf/CFR-2010-title16-vol1-sec301-8.pdf"><span id="translatedtitle">16 CFR 301.8 - Use of terms “Persian <span class="hlt">Lamb</span>,” “Broadtail <span class="hlt">Lamb</span>,” and “Persian-broadtail Lamb” permitted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Use of terms âPersian <span class="hlt">Lamb</span>,â âBroadtail <span class="hlt">Lamb</span>,â and âPersian-broadtail <span class="hlt">Lamb</span>â permitted. 301.8 Section 301.8 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF CONGRESS RULES AND REGULATIONS UNDER FUR PRODUCTS LABELING ACT Regulations § 301.8 Use of terms...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvA..93e2509G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvA..93e2509G&link_type=ABSTRACT"><span id="translatedtitle">Atomic many-body effects and <span class="hlt">Lamb</span> shifts in alkali metals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ginges, J. S. M.; Berengut, J. C.</p> <p>2016-05-01</p> <p>We present a detailed study of the radiative potential method [V. V. Flambaum and J. S. M. Ginges, Phys. Rev. A 72, 052115 (2005), 10.1103/PhysRevA.72.052115], which enables the accurate inclusion of quantum electrodynamics (QED) radiative corrections in a simple manner in atoms and ions over the range 10 ≤Z ≤120 , where Z is the nuclear charge. Calculations are performed for binding energy shifts to the lowest valence s , p , and d <span class="hlt">waves</span> over the series of alkali-metal atoms Na to E119. The high accuracy of the radiative potential method is demonstrated by comparison with rigorous QED calculations in frozen atomic potentials, with deviations on the level of 1%. The many-body effects of core relaxation and second- and higher-order perturbation theory on the interaction of the valence electron with the core are calculated. The inclusion of many-body effects tends to increase the size of the shifts, with the enhancement particularly significant for d <span class="hlt">waves</span>; for K to E119, the self-energy shifts for d <span class="hlt">waves</span> are only an order of magnitude smaller than the s -<span class="hlt">wave</span> shifts. It is shown that taking into account many-body effects is essential for an accurate description of the <span class="hlt">Lamb</span> shift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770021964','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770021964"><span id="translatedtitle"><span class="hlt">Acoustoelasticity</span>. [sound-structure interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dowell, E. H.</p> <p>1977-01-01</p> <p>Sound or pressure variations inside bounded enclosures are investigated. Mathematical models are given for determining: (1) the interaction between the sound pressure field and the flexible wall of a Helmholtz resonator; (2) coupled fluid-structural motion of an acoustic cavity with a flexible and/or absorbing wall; (3) acoustic natural modes in multiple connected cavities; and (4) the forced response of a cavity with a flexible and/or absorbing wall. Numerical results are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26676241','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26676241"><span id="translatedtitle">Effects of suckling duration on growth, slaughtering and carcass quality characteristics of Kivircik <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ekiz, Bulent; Kocak, Omur; Yalcintan, Hulya; Yilmaz, Alper</p> <p>2016-02-01</p> <p>Effects of suckling length (45, 75 and 120 days) and birth type (single and twin) on <span class="hlt">lamb</span> growth, slaughtering and carcass quality characteristics were investigated using 40 Kivircik <span class="hlt">lambs</span>. SC-45 and SC-75 <span class="hlt">lambs</span> were weaned at 45 and 75 days of age, respectively, whilst SC-120 <span class="hlt">lambs</span> remained with their mothers until the end of the experimental period. <span class="hlt">Lambs</span> from all studied groups were slaughtered at 120 days of age. Weaning treatment caused a decrease in average daily gain in SC-45 and SC-75 <span class="hlt">lambs</span>, and therefore, final weight was higher in SC-120 <span class="hlt">lambs</span> than <span class="hlt">lambs</span> from weaned groups. SC-120 <span class="hlt">lambs</span> had higher empty body weight, cold carcass weight, dressing percentage, carcass measurements, carcass fatness (proportions of the kidney knob and channel fat, subcutaneous and intramuscular fat in pelvic limb) and non-carcass fatness (omental and mesenteric fat proportion) than weaned <span class="hlt">lambs</span>. As a conclusion, the potential losses in meat production due to weaning should be considered before deciding the weaning of <span class="hlt">lambs</span> at early ages. PMID:26676241</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..93q4304V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..93q4304V"><span id="translatedtitle">Broad-angle negative reflection and focusing of elastic <span class="hlt">waves</span> from a plate edge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Veres, Istvan A.; Grünsteidl, Clemens; Stobbe, David M.; Murray, Todd W.</p> <p>2016-05-01</p> <p>Guided elastic <span class="hlt">waves</span> in plates, or <span class="hlt">Lamb</span> <span class="hlt">waves</span>, generally undergo reflection and mode conversion upon encountering a free edge. In the case where a backward-propagating <span class="hlt">Lamb</span> <span class="hlt">wave</span> is mode-converted to a forward-propagating <span class="hlt">wave</span> or vice versa, the mode-converted <span class="hlt">wave</span> is reflected on the same side of the surface normal as the incident <span class="hlt">wave</span>. In this paper, we study such negative reflection and show that this effect can be achieved over a broad angular range at a simple plate edge. We demonstrate, through both numerical and experimental approaches, that a plate edge can act as a lens and focus a mode-converted <span class="hlt">Lamb</span> <span class="hlt">wave</span> field. Furthermore, we show that as the <span class="hlt">wave</span> vectors of the incident and mode-converted <span class="hlt">Lamb</span> <span class="hlt">waves</span> approach each other, the mode-converted field nearly retraces the incident field. We propose that broad-angle negative reflection may find application in the nondestructive testing of structures supporting guided <span class="hlt">waves</span> and in the development of new acoustic devices including resonators, lenses, and filters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4517774','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4517774"><span id="translatedtitle">Ewes Direct Most Maternal Attention towards <span class="hlt">Lambs</span> that Show the Greatest Pain-Related Behavioural Responses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Futro, Agnieszka; Masłowska, Katarzyna; Dwyer, Cathy M.</p> <p>2015-01-01</p> <p>Although neonatal farm animals are frequently subjected to painful management procedures, the role of maternal behaviour in pain coping, has not been much studied. We investigated whether ewes were able to distinguish between <span class="hlt">lambs</span> in pain and those that were not, and whether their behaviour altered depending on the severity of <span class="hlt">lamb</span> pain. Eighty male <span class="hlt">lambs</span> were allocated to one of 4 pain treatments within 24 hours of birth. <span class="hlt">Lambs</span> were either handled only (C), bilaterally castrated with tight rubber rings (RR), as for RR but with the application of a Burdizzo clamp immediately proximal to the ring (Combined) or subjected to short scrotum castration (SSC) where the testicles were retained within the abdomen and only the scrotum removed. The behaviour of the ewe, treated <span class="hlt">lamb</span> and untreated sibling where present (n = 54) were recorded for 30 minutes after treatment. Castration treatment increased the expression of abnormal standing and lying postures, specific pain-related behaviours (head-turning, stamping/kicking, easing quarters, tail wagging) and composite pain scores (P<0.001 for all). The greatest expression of pain-related behaviours was shown by <span class="hlt">lambs</span> in the RR group, which were the only group to show rolling responses indicative of severe pain, followed by the SSC group. Ewes expressed more licking/sniffing responses to the RR and SSC <span class="hlt">lambs</span> than towards the Combined and C <span class="hlt">lambs</span> (P<0.05), and oriented most to RR <span class="hlt">lambs</span> and least to C <span class="hlt">lambs</span> (P<0.001). Ewes with two <span class="hlt">lambs</span> also directed more attention towards the treated than the untreated <span class="hlt">lamb</span> (P<0.001). The quantity of maternal care directed towards the <span class="hlt">lamb</span> was positively correlated with the expression of active pain behaviours. The data demonstrate that ewes are able to discriminate between <span class="hlt">lambs</span> in pain and those that are not, and that their response is increased with a greater severity of pain. PMID:26217942</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=chain+AND+reaction&pg=2&id=EJ884194','ERIC'); return false;" href="http://eric.ed.gov/?q=chain+AND+reaction&pg=2&id=EJ884194"><span id="translatedtitle">Using the Mystery of the Cyclopic <span class="hlt">Lamb</span> to Teach Biotechnology</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Jensen, Jamie L.</p> <p>2010-01-01</p> <p>I present a learning cycle that explores different biotechnologies using the process of in situ hybridization as a platform. Students are presented with a cyclopic <span class="hlt">lamb</span> and must use biotechnology to discover the mechanism behind the deformity. Through this activity, students learn about signal transduction and discover the processes of polymerase…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=271908','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=271908"><span id="translatedtitle">Diarrhea due to Cryptosporidium infection in artificially reared <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tzipori, S; Angus, K W; Campbell, I; Clerihew, L W</p> <p>1981-01-01</p> <p>Severe diarrhea which lasted 7 to 12 days occurred in 40 of 48 artificially reared <span class="hlt">lambs</span> within 5 to 12 days of birth, and 16 of them died. Of 16 diarrheic fecal samples examined, 10 contained Cryptosporidium oocysts and 1 contained rotavirus, but no other known enteropathogen was detected. Upon histological examination, cryptosporidia were found in the ilea of three affected <span class="hlt">lambs</span>, and in one of them, villous atrophy and fusion, with epithelial cross-bridging between villi, were present in distal small intestine. Diarrhea was induced in two specific pathogen-free <span class="hlt">lambs</span> by oral inoculation with fecal homogenate containing Cryptosporidium oocysts. Both the small and large intestines became infected with the organism, and associated lesions included stunting, fusion, and deformities of villi in the distal small intestine, with replacement of columnar enterocytes by immature cuboidal cells. Subclinical infections were induced in newborn specific pathogen-free mice and rats. Judged by these data, the <span class="hlt">lamb</span>-derived Cryptosporidium sp. is similar to those recovered from calves, deer, and humans. Images PMID:7263849</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=sample+AND+water&pg=3&id=EJ975563','ERIC'); return false;" href="http://eric.ed.gov/?q=sample+AND+water&pg=3&id=EJ975563"><span id="translatedtitle">A Review of the Latent and Manifest Benefits (<span class="hlt">LAMB</span>) Scale</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Muller, Juanita; Waters, Lea</p> <p>2012-01-01</p> <p>The latent and manifest benefits (<span class="hlt">LAMB</span>) scale (Muller, Creed, Waters & Machin, 2005) was designed to measure the latent and manifest benefits of employment and provide a single scale to test Jahoda's (1981) and Fryer's (1986) theories of unemployment. Since its publication in 2005 there have been 13 studies that have used the scale with 5692…</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=259070','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=259070"><span id="translatedtitle">Cultivar Preference of <span class="hlt">Lambs</span> Grazing Forage Chicory in Ohio</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>This project compared grazing preferences of <span class="hlt">lambs</span> between seven cultivars of forage chicory (Cichorium intybus L.). This on-farm trial was conducted in central Ohio (40.53 degrees N, 82.46 degrees W, 1089 ft above sea level). The chicory was established by using conventional tillage in Bogart Silt...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=235943','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=235943"><span id="translatedtitle">Does breed of ram affect ewe and <span class="hlt">lamb</span> productivity?</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Systematic use of breed diversity in terminal crossbreeding systems can improve the efficiency of commercial <span class="hlt">lamb</span> production. Data from controlled research should be used to select the genetic line or lines of rams to use in terminal crossbreeding systems. Thus, research is underway at the USDA, ARS...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=279870','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=279870"><span id="translatedtitle">Fabricated carcass measurements in terminally sired F1 <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Scientific data for carcass traits of terminal-sire sheep breeds can be used to improve the value of market <span class="hlt">lambs</span>, but information is lacking for modern terminal-sire breeds in the United States. Thus, the effects of terminal-sire breed on 14 fabricated carcass measurements were determined in F1 wet...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.661a2049V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.661a2049V"><span id="translatedtitle">Microwave filter based on <span class="hlt">Lamb</span> modes for optoelectronic generator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vitko, V. V.; Nikitin, A. A.; Kondrashov, A. V.; Nikitin, A. A.; Ustinov, A. B.; Belyavskiy, P. Yu; Kalinikos, B. A.; Butler, J. E.</p> <p>2015-12-01</p> <p>Experimental results for narrowband filter based on yttrium iron garnet film epitaxially grown on gadolinium gallium garnet substrate have been shown. The principle of operation of the filter is based on excitation of <span class="hlt">Lamb</span> modes in the substrate. We demonstrated also that the use of single crystal diamond as a substrate will significantly reduce the phase noise of the designed optoelectronic microwave generator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1576804','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1576804"><span id="translatedtitle">Copper toxicity in confinement-housed ram <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lewis, N J; Fallah-Rad, A H; Connor, M L</p> <p>1997-01-01</p> <p>Fourteen Suffolk rams (6 mo) were diagnosed with chronic copper poisoning. Preliminary results indicated that a combination of serum aspartate aminotransferase, gamma glutamyltransferase, and copper could be used as a test so that high risk <span class="hlt">lambs</span> could be treated more aggressively. PMID:9262859</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/2592285','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/2592285"><span id="translatedtitle">Nutritive value of a vegetable amaranth cultivar for growing <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pond, W G; Lehmann, J W</p> <p>1989-11-01</p> <p>Current interest in amaranth as a food resource for humans and animals has been stimulated by activities in germplasm collection and testing in the U.S. Fifteen growing, intact male <span class="hlt">lambs</span> weighing 18.7 kg were assigned randomly to three diets (five <span class="hlt">lambs</span>/diet) for a 14-d growth trial followed immediately by an 8-d (4-d adjustment, 4-d collection) digestion and N balance trial to determine the utilization of the forage component (leaves and stems) of an African cultivar (Zimbabwe cultivar PI 482049, Amaranthus cruentus L.) All diets contained 40.95% ground corn, 8.0% soybean meal and 1.05% mineral-vitamin supplement plus either 50% ground alfalfa hay, 25% ground alfalfa hay plus 25% ground amaranth forage or 50% ground amaranth forage. <span class="hlt">Lambs</span> had ad libitum access to feed during the growth trial and at 4% of BW daily during the digestion and N balance period. Replacement of half or all the alfalfa in the diet with amaranth had no effect on weight gain or feed utilization. Apparent digestibility of cell contents, NDF, ADF, cellulose, ADL, N and GE and percentage of absorbed N retained did not differ among the three diets. The amaranth vegetable cultivar Zimbabwe PI 482049 promoted weight gain and feed utilization equal to that obtained with alfalfa as the sole forage for growing <span class="hlt">lambs</span>. Additional research is needed to evaluate further the potential role of forage/vegetable amaranth as an animal feed resource. PMID:2592285</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=226417','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=226417"><span id="translatedtitle">Finishing <span class="hlt">lambs</span> and kids on pasture in Appalachia</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Traditional sheep, hair sheep and meat goat industries are growing rapidly in the Appalachian Region, particularly on small farms, to help produce meats for ethnic markets. Numerous forage types and qualities are used in small ruminant finishing systems. With the expansion of non-traditional <span class="hlt">lamb</span> ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JPhCS.530a2001L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPhCS.530a2001L"><span id="translatedtitle">Horace <span class="hlt">Lamb</span> & Osborne Reynolds: Remarkable Mancunians ... and their Interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Launder, B. E.</p> <p>2014-08-01</p> <p>The paper provides glimpses into the professional lives of arguably, the two outstanding fluid mechanicists of their time who were simultaneously professors at Owens College, Manchester. Their interactions with each other were sometimes amicable but, equally, sometimes testy and their views on their common professional subject differed radically. Reynolds was appointed to the Chair of Engineering in 1868 at the age of 25 against strong competition while Horace <span class="hlt">Lamb</span>, graduating a decade after Reynolds, was appointed as the inaugural Professor of Applied Mathematics at the University of Adelaide where he stayed for nine years before being appointed to a chair at Owens College in 1885. Among their various interactions the most significant arose from Reynolds' famous "Reynolds averaging" paper. That was sent for review by <span class="hlt">Lamb</span> who was critical of the paper but finally recommended that a revised version be published since Reynolds had essentially invented the subject. Reynolds, in his turn, criticised <span class="hlt">Lamb</span>'s patronizing reference to engineers' approach to fluid mechanics in a draft revision of his book Hydrodynamics. Nevertheless, on Reynolds' death in 1912, it was <span class="hlt">Lamb</span> who attended his funeral on behalf of the University and the Royal Society and who later wrote a moving, much cited obituary of him.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=208756','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=208756"><span id="translatedtitle">Relationship between calpastatin activity and <span class="hlt">lamb</span> carcass characteristics.</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The purpose of this study was to determine if calpastatin activity (CALP) was related to the amount of intramuscular fat (IMF) and Warner-Bratzler shear force (WBS) in <span class="hlt">lamb</span> carcasses. Market wethers representing three sire lines (n = 40, average live weight of 68.9 kg) were harvested at the OSU Mea...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=231022','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=231022"><span id="translatedtitle">STOCKPILED PRAIRIEGRASS PROVIDES HIGH-QUALITY FALL GRAZING FOR <span class="hlt">LAMBS</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>New varieties of prairiegrass (Bromus catharticus Vahl. = B. willdenowii Kunth.) exhibit improved persistence over ‘Matua’ under USA growing conditions, but animal performance data is lacking. We evaluated performance of <span class="hlt">lambs</span> grazing stockpiled ‘Dixon’ prairiegrass on West Virginia hill pasture in...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=209879','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=209879"><span id="translatedtitle">Stockpiled Prairie Grass For Fall-Grazing <span class="hlt">Lambs</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>New varieties of prairiegrass (Bromus catharticus Vahl. = B. willdenowii Kunth.) exhibit improved persistence over 'Matua' under USA growing conditions, but animal performance data is lacking. Therefore, we evaluated performance of <span class="hlt">lambs</span> grazing fall-stockpiled 'Dixon' prairiegrass on a West Virgin...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5024383','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5024383"><span id="translatedtitle">Effects of ozone on <span class="hlt">lamb</span> tracheal mucosa. Quantitative glycoconjugate histochemistry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mariassy, A.T.; Sielczak, M.W.; McCray, M.N.; Abraham, W.M.; Wanner, A. )</p> <p>1989-11-01</p> <p>Whether or not the previously reported O3-induced abnormality in the postnatal development of tracheal secretory function in <span class="hlt">lambs</span> is accompanied by changes in epithelial cell populations and their glycoconjugate composition was determined. Six <span class="hlt">lambs</span> were killed at birth and 12 <span class="hlt">lambs</span> at age 2 weeks. Of the latter 12, six were exposed to O3 (1 ppm, 4 hours daily for 5 days during the 1st week of life) and five had air-sham exposures (controls). Tracheal glycoconjugates were localized in situ with lectins to detect N-acetyl-galactosamine (galNAc), alpha-D-galactose (alpha-gal), beta-D-gal(1----3)-galNAc (beta-gal), and fucose (fuc). Mean (+/- SD) epithelial cell density (cells/mm basal lamina) was 418 +/- 57 in the newborns, 385 +/- 63 in controls (P was not significant), and 342 +/- 47 in O3-exposed <span class="hlt">lambs</span> (P less than 0.05). Mucous cell density was 87 +/- 12 in newborns, 63 +/- 10 in controls (P less than 0.05), and 76 +/- 10 in O3 exposed <span class="hlt">lambs</span> (P was not significant). Ciliated cells remained unchanged from birth to 2 weeks (P was not significant), but decreased (P less than 0.05) in O3-exposed <span class="hlt">lambs</span>. All counted mucous cells contained fuc and galNAc at birth and retained these residues after sham and O3 exposure. The alpha-gal-containing mucous cells declined from 97 +/- 13 to 7 +/- 1 (P less than 0.05) and beta-gal containing cells from 39 +/- 5 to 25 +/- 4 in controls. In contrast, cells containing alpha-gal 71 +/- 10 remained at newborn levels (97 +/- 13) and beta-gal-containing cells increased from 40 +/- 5 at birth to 58 +/- 8 in O3-exposed animals (P less than 0.05). It was concluded that early postnatal exposure of <span class="hlt">lambs</span> to O3 causes a decrease in epithelial cell density, but retards the developmental decrease in the number of tracheal mucous cells and alters the lectin detectable carbohydrate composition of mucus in these cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27462932','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27462932"><span id="translatedtitle"><span class="hlt">Lamb</span> survival, glutathione redox state and immune function of neonates and <span class="hlt">lambs</span> from periparturient Merino ewes supplemented with rumen-protected methionine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Shimin; Lei, Jason; Hancock, Serina; Scanlan, Victoria; Broomfield, Steve; Currie, Andrew; Thompson, Andrew</p> <p>2016-10-01</p> <p>Wool growth in Merino sheep demands a high level of sulphur amino acids, competing with body growth and the immune system, which may play a role in increasing the risk of <span class="hlt">lamb</span> mortality. The hypothesis that dietary supplementation of methionine (Met) to Merino ewes during the late stages of pregnancy will improve foetal growth and alter immune competency of ewes and <span class="hlt">lambs</span> was tested in a total of 120 grazing, pregnant Merino ewes. Sixty ewes were group-supplemented with 6.3 g/d rumen-protected Met (Met-Plus) per sheep from day 111 of pregnancy until day 7 after <span class="hlt">lambing</span>, and the other 60 animals were used as a non-supplemented Control. <span class="hlt">Lambs</span> from Met-supplemented ewes tended to be 10% heavier than Control <span class="hlt">lambs</span> (p = 0.10), which did not affected the survival rate at weaning significantly. The supplemented ewes had slightly higher concentrations of total glutathione (GSH) in plasma at <span class="hlt">lambing</span> (p < 0.06), but there were no differences between 1 and 3 months post-<span class="hlt">lambing</span> in GSH, glutathione disulphide (GSSG) and the GSSG:GSH ratio. The GSSG:GSH ratio in the blood of ewes was elevated at <span class="hlt">lambing</span> (p < 0.05), hinting that ewes were undergoing increased oxidative stress. The Met supplementation elevated the total IgG concentration (p < 0.05) in <span class="hlt">lambs</span> aged 4 and 6 weeks, but did not change the IgG concentrations in colostrum and in plasma of 1-week-old <span class="hlt">lambs</span>, and white blood cell counts and leukocyte types. The trend towards higher <span class="hlt">lamb</span> birth weights in the Met-supplemented group requires further investigation as this may influence survival at birth and weaning. PMID:27462932</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002SPIE.4693..279L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002SPIE.4693..279L"><span id="translatedtitle">Local interaction modeling for acousto-ultrasonic <span class="hlt">wave</span> propagation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, B. C.; Staszewski, Wieslaw J.</p> <p>2002-07-01</p> <p>Damage detection in metallic structures has been the subject of many investigations. Recent developments have shown applications of acousto-ultrasonic and <span class="hlt">Lamb</span> <span class="hlt">wave</span> testing. <span class="hlt">Lamb</span> <span class="hlt">wave</span> inspection is based on theory of longitudinal <span class="hlt">waves</span> propagating in plates. In general, the principles of acousto-ultrasonic and <span class="hlt">Lamb</span> <span class="hlt">wave</span> inspection techniques are similar. Damage in a structure is identified by a change in the output signal. Previous studies show that even simple input signals can lead to complex output <span class="hlt">waves</span>, which are difficult to interpret. It is clear that knowledge and understanding of <span class="hlt">wave</span> propagation in analyzed structures can ease the interpretation of damage detection results. The paper reports an application of local interaction modeling of acousto-ultrasonic <span class="hlt">waves</span> in metallic structures. The focus of the analysis is on one-dimensional interactions between different material boundaries. This includes modeling of acousto-ultrasonic <span class="hlt">waves</span> in piezoceramic, adhesive glue and copper in an actuator/sensor configuration. The study also involves experimental validation of the simulation results. The method shows the potential for modeling of acousto-ultrasonic <span class="hlt">waves</span> in complex media for damage detection applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25089786','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25089786"><span id="translatedtitle">A model explaining and predicting <span class="hlt">lamb</span> flavour from the aroma-active chemical compounds released upon grilling light <span class="hlt">lamb</span> loins.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bueno, Mónica; Campo, M Mar; Cacho, Juan; Ferreira, Vicente; Escudero, Ana</p> <p>2014-12-01</p> <p>The objective of the work is to understand the role of the different aroma compounds in the perception of the local "<span class="hlt">lamb</span> flavour" concept. For this, a set of 70 loins (Longissimus dorsi) from approximately seventy day-old Rasa Aragonesa male <span class="hlt">lambs</span> were grilled and the aroma-active chemicals released during the grilling process were trapped and analyzed. Carbonyl compounds were derivatizated and determined by GC-NCI-MS, whereas other aromatic compounds were directly analyzed by GC-GC-MS. Odour activity values (OAVs) were calculated using their odour threshold values in air. <span class="hlt">Lamb</span> flavour could be satisfactory explained by a partial least-squares model (74% explained variance in cross-validation) built by the OAVs of 32 aroma-active chemical compounds. The model demonstrates that the <span class="hlt">lamb</span> flavour concept is the result of a complex balance. Its intensity critically and positively depends to the levels of volatile fatty acids and several dimethylpyrazines while is negatively influenced by the different alkenals and alkadienals. (E,E)-2,4-decadienal and (E)-2-nonenal showed top OAVs. PMID:25089786</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AIPC.1511..398Z&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AIPC.1511..398Z&link_type=ABSTRACT"><span id="translatedtitle">Study of concrete's behavior under 4-point bending load using Coda <span class="hlt">Wave</span> Interferometry (CWI) analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y.; Abraham, O.; Chapeleau, X.; Cottineau, L.-M.; Tournat, V.; Le Duff, A.; Lascoup, B.; Durand, O.</p> <p>2013-01-01</p> <p>Coda <span class="hlt">Wave</span> Interferometry (CWI) is an ultrasonic NDT method suitable for complex material such as concrete that can precisely measure small propagation velocity variation (10-2%). By measuring variation of propagation velocity in concrete caused by <span class="hlt">acoustoelasticity</span> phenomena, CWI analysis can be used to monitor concrete's internal stress level. For the first time, CWI is used to measure propagation velocity variations due to a stress field in a concrete beam under four-points bending test, which contains simultaneously compressive and tensile stress. Embedded optical-fiber sensors, strain gauges are used in the experiment, in order to confirm and validate the CWI analysis result. Thermocouples are also embedded into concrete beams for monitoring internal temperature fluctuations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007SPIE.6423E..2VS','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007SPIE.6423E..2VS"><span id="translatedtitle">Nature defect evaluation of laser welded thin plate using laser guide <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, Kyung Seok; Kim, Jae Yeol</p> <p>2007-07-01</p> <p>The longitudinal, shear and surface <span class="hlt">waves</span> have been used to an Ultrasonic <span class="hlt">wave</span> exploration method to identify internal defects but it has technical difficulties to detect defects in a limited space with having several millimeters board thickness. It is applicable to use <span class="hlt">Lamb</span> <span class="hlt">wave</span>, a kind of induction ultrasonic <span class="hlt">wave</span> that has a relatively high inspection efficiency and defect detection sensitiveness compare to perpendicular or square explorations in terms of the internal defect detection in these kinds of thin board. The <span class="hlt">Lamb</span> <span class="hlt">wave</span> is a special type of induction ultrasonic <span class="hlt">wave</span> to propagate to a board and it is effective to inspect such as board structure, cell structure, etc. Recently a laser is being used to generate <span class="hlt">Lamb</span> <span class="hlt">wave</span> but it not being widely utilized because of difficulties in receiving and selective generation in various modes <span class="hlt">Lamb</span> <span class="hlt">wave</span> generating and a low S/N ratio, wide range of generating frequency band when a laser is used. This paper aims to study that the defect exploration method to specimen's thickness, using an characteristic of an ultrasonic <span class="hlt">wave</span> generating in ablation area and thermoelasticity area, has been applied to using a way of receiving it by Air-Coupled Transducer and transmitting it by an ultrasonic <span class="hlt">wave</span> and a way of non-contact receiving and transmitting ultrasonic <span class="hlt">wave</span> using a laser. The longitudinal, shear <span class="hlt">waves</span> have been used in 60mm thickness specimen and <span class="hlt">Lamb</span> <span class="hlt">wave</span> in 3mm to run artificial defect detection test. In this way, the usefulness of non-contact laser ultrasonic <span class="hlt">wave</span> has been verified. To confirm the possibility of implementation on natural defect existing at real welding part, thickness in 3mm SM45C and STS304 artificial defect specimen has been made and defect detection test using <span class="hlt">Lamb</span> <span class="hlt">wave</span> has been executed. Detected signal by signal treatment has been expressed in visual not RF signal. By doing so the convenience of defect detection has been attempted and the effectiveness of defect signal visualization using <span class="hlt">Lamb</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JSMTE..05..011G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JSMTE..05..011G"><span id="translatedtitle">Can a <span class="hlt">lamb</span> reach a haven before being eaten by diffusing lions?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabel, Alan; Majumdar, Satya N.; Panduranga, Nagendra K.; Redner, S.</p> <p>2012-05-01</p> <p>We study the survival of a single diffusing <span class="hlt">lamb</span> on the positive half line in the presence of N diffusing lions that all start at the same position L to the right of the <span class="hlt">lamb</span> and a haven at x = 0. If the <span class="hlt">lamb</span> reaches this haven before meeting any lion, the <span class="hlt">lamb</span> survives. We investigate the survival probability of the <span class="hlt">lamb</span>, SN(x, L), as a function of N and the respective initial positions of the <span class="hlt">lamb</span> and the lions, x and L. We determine SN(x, L) analytically for the special cases of N = 1 and N\\rightarrow \\infty . For large but finite N, we determine the unusual asymptotic form whose leading behavior is SN(z) ~ N-z2, with z = x/L. Simulations of the capture process very slowly converge to this asymptotic prediction as N reaches 10500.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27285926','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27285926"><span id="translatedtitle">A supplement containing multiple types of gluconeogenic substrates alters intake but not productivity of heat-stressed Afshari <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mahjoubi, E; Amanlou, H; Hossein Yazdi, M; Aghaziarati, N; Noori, G R; Vahl, C I; Bradford, B J; Baumgard, L H</p> <p>2016-06-01</p> <p>Thirty-two Afshari <span class="hlt">lambs</span> were used in a completely randomized design with a 2 × 2 factorial arrangement of treatments to evaluate a nutritional supplement designed to provide multiple gluconeogenic precursors during heat stress (HS). <span class="hlt">Lambs</span> were housed in thermal neutral (TN) conditions and fed ad libitum for 8 d to obtain covariate data (period 1 [P1]) for the subsequent experimental period (period 2 [P2]). During P2, which lasted 9 d, half of the <span class="hlt">lambs</span> were subjected to HS and the other 16 <span class="hlt">lambs</span> were maintained in TN conditions but pair fed (PFTN) to the HS <span class="hlt">lambs</span>. Half of the <span class="hlt">lambs</span> in each thermal regime were fed (top-dressed) 100 g/d of a feed supplement designed to provide gluconeogenic precursors (8 <span class="hlt">lambs</span> in HS [heat stress with Glukosa {HSG}] and 8 <span class="hlt">lambs</span> in PFTN [pair-fed thermal neutral with Glukosa]) and the other <span class="hlt">lambs</span> in both thermal regimes were fed only the basal control diet (HS without Glukosa [HSC] and pair-fed thermal neutral without Glukosa). Heat stress decreased DMI (14%) and by design there were no differences between the thermal treatments, but HSG <span class="hlt">lambs</span> had increased DMI (7.5%; < 0.05) compared with the HSC <span class="hlt">lambs</span>. Compared with PFTN <span class="hlt">lambs</span>, rectal temperature and skin temperature at the rump, shoulder, and legs of HS <span class="hlt">lambs</span> were increased ( < 0.05) at 0700 and 1400 h. Rectal temperature at 1400 h decreased for HSG <span class="hlt">lambs</span> (0.15 ± 0.03°C; < 0.05) compared with HSC <span class="hlt">lambs</span>. Despite similar DMI between thermal treatments, ADG for HS and PFTN <span class="hlt">lambs</span> in P2 was decreased 55 and 85%, respectively, compared with <span class="hlt">lambs</span> in P1 ( < 0.01). Although the prefeeding glucose concentration was not affected by thermal treatment or diet, HSG <span class="hlt">lambs</span> had increased postfeeding glucose concentration compared with HSC <span class="hlt">lambs</span> ( < 0.05). In contrast to the glucose responses, circulating insulin was influenced only by thermal treatment; HS <span class="hlt">lambs</span> had increased insulin concentration ( < 0.01) before feeding and decreased concentration ( < 0.05) after feeding compared with PFTN</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhFl...26e6104M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhFl...26e6104M"><span id="translatedtitle">Aerodynamic force by <span class="hlt">Lamb</span> vector integrals in compressible flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mele, Benedetto; Tognaccini, Renato</p> <p>2014-05-01</p> <p>A new exact expression of the aerodynamic force acting on a body in steady high Reynolds number (laminar and turbulent) compressible flow is proposed. The aerodynamic force is obtained by integration of the <span class="hlt">Lamb</span> vector field given by the cross product of vorticity times velocity. The result is obtained extending a theory developed for the incompressible case. A decomposition in lift and drag contribution is obtained in the two-dimensional case. The theory links the force generation to local flow properties, in particular to the <span class="hlt">Lamb</span> vector field and to the kinetic energy. The theoretical results are confirmed analyzing numerical solutions obtained by a standard Reynolds Averaged Navier-Stokes solver. Results are discussed for the case of a two-dimensional airfoil in subsonic, transonic, and supersonic free stream conditions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6861012','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6861012"><span id="translatedtitle">Cardiorespiratory response to cyanide of arterial chemoreceptors in fetal <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Itskovitz, J.; Rudolph, A.M.</p> <p>1987-05-01</p> <p>Cardiorespiratory response to the stimulation of the carotid and aortic receptors by sodium cyanide was examined in fetal <span class="hlt">lambs</span> in utero at 0.8 (120 days) gestation. Injections of 50-400 ..mu..g cyanide into the inferior vena cava or the carotid artery of intact fetuses elicited bradycardia and respiratory responses that varied from a single gasp to rhythmic respiratory movements but no significant change in arterial blood pressure. Carotid sinus denervation eliminated the cardiorespiratory response to intracarotid injection of cyanide and sinoaortic denervation abolished the response to inferior vena caval injection. It is concluded that in fetal <span class="hlt">lamb</span> in utero the aortic and carotid bodies are active, and hypoxic stimulation of these chemoreceptors results in cardiorespiratory response characterized by slowing of fetal heart rate, respiratory effort, and no consistent change in arterial blood pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8050952','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8050952"><span id="translatedtitle">Photosensitization associated with exposure to Pithomyces chartarum in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hansen, D E; McCoy, R D; Hedstrom, O R; Snyder, S P; Ballerstedt, P B</p> <p>1994-05-15</p> <p>An epidemic of photosensitization was observed in a group of <span class="hlt">lambs</span> on irrigated autumn pasture in western Oregon. Signs included crusting, necrosis, and sloughing of the skin over the nostrils, lips, and ears, and of the mucous membranes of the buccal regions. Microscopic examination of plant material from the pasture disclosed spores of Pithomyces chartarum. This fungus has been documented as a causal factor in photosensitization in sheep and cattle (facial eczema) in other parts of the world. An infective agent or other plant material that could have induced the clinical signs in the <span class="hlt">lambs</span> was not evident. Weather and humidity conditions were ideal for fungal growth during the grazing period, and the fungus was detected in large numbers before and during the epidemic. Even though facial eczema has not been reported previously in northwestern United States, we feel the circumstances surrounding this epidemic warrant such a diagnosis. PMID:8050952</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012HyInt.204...89R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012HyInt.204...89R"><span id="translatedtitle">The collective <span class="hlt">Lamb</span> shift in nuclear γ-ray superradiance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Röhlsberger, Ralf</p> <p>2012-03-01</p> <p>The electromagnetic transitions of Mössbauer nuclei provide almost ideal two-level systems to transfer quantum optical concepts into the regime of hard x-rays. If many identical atoms collectively interact with a resonant radiation field, one observes (quantum) optical properties that are strongly different from those of a single atom. The most prominent effect is the broadening of the resonance line known as collective enhancement, resulting from multiple scattering of real photons within the atomic ensemble. On the other hand, the exchange of virtual photons within the ensemble leads to a tiny energy shift of the resonance line, the collective <span class="hlt">Lamb</span> shift, that remained experimentally elusive for a long time after its prediction. Here we illustrate how highly brilliant synchrotron radiation allows one to prepare superradiant states of excited Mössbauer nuclei, an important condition for observation of the collective <span class="hlt">Lamb</span> shift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17032469','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17032469"><span id="translatedtitle">The use of chicory for parasite control in organic ewes and their <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Athanasiadou, S; Gray, D; Younie, D; Tzamaloukas, O; Jackson, F; Kyriazakis, I</p> <p>2007-02-01</p> <p>The aim of the present study was to investigate the potential benefits of grazing lactating ewes and their <span class="hlt">lambs</span> on chicory (Cichorium intybus). Fifty-six certified organic twin-rearing ewes were either drenched with an anthelmintic or not, within 2 days after parturition and were grazed upon either grass/clover or chicory pastures. Around 12 weeks after parturition a subset of 12 <span class="hlt">lambs</span> per treatment was slaughtered for worm number and parasite species determination. The faecal egg counts of <span class="hlt">lambs</span> from undrenched ewes grazing on chicory were significantly lower than those of <span class="hlt">lambs</span> from undrenched ewes grazing on grass. <span class="hlt">Lambs</span> grazing on chicory had similar abomasal worm counts as those grazing on grass at 12 weeks of age; the predominant species was Teladorsagia circumcincta. There was no difference between the intestinal worm counts in <span class="hlt">lambs</span> grazing on grass or chicory, with Trichostrongylus vitrinus being the predominant species. Liveweight gains over the 126-day experimental period were significantly higher in <span class="hlt">lambs</span> from drenched than those from undrenched ewes. <span class="hlt">Lambs</span> from undrenched ewes grazing on chicory had higher liveweight gains compared to those from undrenched ewes grazing on grass. Although chicory grazing did not affect ewe nematode egg excretion, it resulted in lower egg counts in <span class="hlt">lambs</span> and improved their liveweight gains to the same level as those deriving from drenched ewes. PMID:17032469</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27451234','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27451234"><span id="translatedtitle">Origin assignment by multi-element stable isotopes of <span class="hlt">lamb</span> tissues.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Shumin; Guo, Boli; Wei, Yimin</p> <p>2016-12-15</p> <p>The carbon, nitrogen and hydrogen isotopic compositions in <span class="hlt">lamb</span> meat and wool samples under two feeding regimes from five different regions of China were determined by IRMS, which is to investigate their potential for assigning the <span class="hlt">lamb</span> meat according to geographical origins. The δ(13)C, δ(15)N and δ(2)H values in <span class="hlt">lamb</span> tissues had significant differences among different regions, with the δ(13)C value is highly related to that of the <span class="hlt">lamb</span> feeds (p<0.01) and the δ(2)H value is significantly correlated with <span class="hlt">lamb</span> drinking water (p<0.05). Moreover, δ(13)C, δ(15)N and δ(2)H values of <span class="hlt">lamb</span> muscle are all highly correlated with the wool samples. A total correct classification of 88.9% and 83.8% were obtained from the combination of C, N and H isotopes of <span class="hlt">lamb</span> muscle and wool, respectively. These results demonstrate that multi-element isotopes are effective in identifying the geographical origin of <span class="hlt">lamb</span> meat. Moreover, both muscle and hair tissue can be used for <span class="hlt">lamb</span> traceability. PMID:27451234</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.S21A1689S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.S21A1689S"><span id="translatedtitle">Monitoring Stress Changes in a Concrete Bridge with Acoustic <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stähler, S.; Sens-Schönfelder, C.; Niederleithinger, E.; Pirskawetz, S.</p> <p>2009-12-01</p> <p>The sensitivity of coda <span class="hlt">waves</span> for material changes has been demonstrated in various environments ranging form laboratory scale to regional seismology. Here we present a test for monitoring stress induced velocity variations in a concrete construction. The construction is a bridge made of reinforced concrete in Germany that is build in incremental launching method (Taktschiebe-Mode). This means that construction takes place at one end of the bridge from which the bridge is successively pushed over the pillars as the constructions continues. During the movement of the construction over the pillars the stress in the girder and the deck slab undergoes changes between 0 and 14 MPa in horizontal direction. We used seismic equipment to induce elastic <span class="hlt">waves</span> in the deck slab of the bridge at different position of the array relative to the supporting pillars. Comparing reverberating <span class="hlt">waves</span> in slab recorded at different stress states we can infer changes in the propagation velocity. The observed velocity change is compared to modeled stress variations in the slab. Comparison is difficult due to imprecise positioning of the array and the spatially periodic stress variations. But we can show that the observed velocity variation is in agreement with the predictions from the stress model. Samples of the concrete used in the bridge are tested under different loads in the laboratory to infer the stress-velocity relation. The experiments show that the <span class="hlt">acousto-elastic</span> effect in the specific concrete can account for the observed velocity variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6168296','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6168296"><span id="translatedtitle">Nuclear polarization contribution to the <span class="hlt">Lamb</span> shift in heavy atoms</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Plunien, G.; Mueller, B.; Greiner, W.; Soff, G.</p> <p>1989-05-15</p> <p>The energy shift of the 1s/sub 1/2/ state in /sub <2//sub 92//sup 38/U due to virtual excitation of nuclear rotational modes is shown to be a considerable correction for atomic high-precision experiments. In contrast to this, nuclear polarization effects are of minor importance for <span class="hlt">Lamb</span>-shift studies in /sub <2//sub 82//sup 08/Pb.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20416722','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20416722"><span id="translatedtitle">Pre-rigor infusion with kiwifruit juice improves <span class="hlt">lamb</span> tenderness.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Han, J; Morton, J D; Bekhit, A E D; Sedcole, J R</p> <p>2009-07-01</p> <p>The ability of pre-rigor infusion of kiwifruit juice to improve the tenderness of <span class="hlt">lamb</span> was investigated. <span class="hlt">Lamb</span> carcasses were infused (10% body weight) with fresh kiwifruit juice (Ac), water (W) and a non-infusion control (C) treatment. Infusion treatment had no effect on <span class="hlt">lamb</span> hot carcass weight, cold carcass weight and chilling evaporative losses. The infused treatment carcasses of Ac and W had lower (P<0.05) pH values than C carcasses during the initial 12h post-mortem. The LD muscles from Ac carcasses were more tender with significantly lower shear force (P<0.001) compared with C and W carcasses during the six days following infusion with the kiwifruit juice. The enhanced proteolytic activity (P=0.002) resulting from the infused kiwifruit juice in Ac carcasses was associated with significant degradation of the myofibrillar proteins, appearance of new peptides and activation of m-calpain during post-mortem ageing. Thus, kiwifruit juice is powerful and easily prepared meat tenderizer, which could contribute efficiently and effectively to the meat tenderization process. PMID:20416722</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25049953','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25049953"><span id="translatedtitle">Ingestive behavior of <span class="hlt">lambs</span> confined in individual and group stalls.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Filho, A Eustáquio; Carvalho, G G P; Pires, A J V; Silva, R R; Santos, P E F; Murta, R M; Pereira, F M</p> <p>2014-02-01</p> <p>The experiment was conducted to evaluate the ingestive behavior of <span class="hlt">lambs</span> confined in individual and group stalls. We used thirty-four <span class="hlt">lambs</span> in their growing phase, aged an average of three months, with mean initial live weight of 17.8±5.2 kg. They were allotted in a completely randomized design with 24 animals kept in individual stalls and 10 animals confined as a group. The experiment lasted for a total of 74 days, and the first 14 days were dedicated to the animals' adaption to the management, facilities and diets. The data collection period lasted 60 days, divided into three 20-d periods for the behavior evaluation. The animals were subjected to five days of visual observation during the experiment period, by the quantification of 24 h a day, with evaluations on the 15th day of each period and an interim evaluation consisting of two consecutive days on the 30th and 31st day of the experiment. The animals confined as a group consumed less (p<0.05) fiber. However, the animals confined individually spent less (p<0.05) time on feeding, rumination and chewing activities and longer in idleness. Therefore, the lower capacity of <span class="hlt">lambs</span> confined in groups to select their food negatively affects their feeding behavior. PMID:25049953</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/821742','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/821742"><span id="translatedtitle">In utero fetal <span class="hlt">lamb</span> thyroidectomy and thyroid autograft transplantation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Belin, R P; Hollingsworth, D R; Reid, M C; Davis, S L; Beihn, R</p> <p>1976-01-01</p> <p>Our fetal surgical model was utilized to perform in utero fetal <span class="hlt">lamb</span> thyroidectomy and autograft transplantation of thyroid tissue to fetal thigh at 82-93 days gestation. Successful in utero transplantation was possible in two of six experimental animals. In one twin pregnancy with an unoperated control <span class="hlt">lamb</span>, observations were continued to age six months. The athyrotic <span class="hlt">lamb</span> with a thigh autograft was larger at birth and had a transient weak sucking reflex and awkward gait. It then grew and developed normally with no stigmata of cretinism or delay in bone maturation. At age six months an increase in thyroid stimulating hormone (oTSH) was the single distinguishing observation in the twin with the transplant. Although oTSH levels were elevated to age six months, the pituitary continued to be responsive to thyrotropin releasing hormone (TRH) stimulation. These findings suggest that in utero transplantation of thyroid tissue is technically feasible and that the previously described development of in utero cretinism following fetal thyroidectomy can be prevented by a functioning autograft. This technique will be useful in attempting allograft transplantation in utero. PMID:821742</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4093203','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4093203"><span id="translatedtitle">Ingestive Behavior of <span class="hlt">Lambs</span> Confined in Individual and Group Stalls</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Filho, A. Eustáquio; Carvalho, G. G. P.; Pires, A. J. V.; Silva, R. R.; Santos, P. E. F.; Murta, R. M.; Pereira, F. M.</p> <p>2014-01-01</p> <p>The experiment was conducted to evaluate the ingestive behavior of <span class="hlt">lambs</span> confined in individual and group stalls. We used thirty-four <span class="hlt">lambs</span> in their growing phase, aged an average of three months, with mean initial live weight of 17.8±5.2 kg. They were allotted in a completely randomized design with 24 animals kept in individual stalls and 10 animals confined as a group. The experiment lasted for a total of 74 days, and the first 14 days were dedicated to the animals’ adaption to the management, facilities and diets. The data collection period lasted 60 days, divided into three 20-d periods for the behavior evaluation. The animals were subjected to five days of visual observation during the experiment period, by the quantification of 24 h a day, with evaluations on the 15th day of each period and an interim evaluation consisting of two consecutive days on the 30th and 31st day of the experiment. The animals confined as a group consumed less (p<0.05) fiber. However, the animals confined individually spent less (p<0.05) time on feeding, rumination and chewing activities and longer in idleness. Therefore, the lower capacity of <span class="hlt">lambs</span> confined in groups to select their food negatively affects their feeding behavior. PMID:25049953</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3857252','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3857252"><span id="translatedtitle">Cerebral Autoregulation Is Minimally Influenced by the Superior Cervical Ganglion in Two- Week-Old <span class="hlt">Lambs</span>, and Absent in Preterm <span class="hlt">Lambs</span> Immediately Following Delivery</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Czynski, Adam J.; Terry, Michael H.; Deming, Douglas D.; Power, Gordon G.; Buchholz, John N.; Blood, Arlin B.</p> <p>2013-01-01</p> <p>Cerebral vessels in the premature newborn brain are well supplied with adrenergic nerves, stemming from the superior cervical ganglia (SCG), but their role in regulation of blood flow remains uncertain. To test this function twelve premature or two-week-old <span class="hlt">lambs</span> were instrumented with laser Doppler flow probes in the parietal cortices to measure changes in blood flow during changes in systemic blood pressure and electrical stimulation of the SCG. In <span class="hlt">lambs</span> delivered prematurely at ∼129 days gestation cerebral perfusion and driving pressure demonstrated a direct linear relationship throughout the physiologic range, indicating lack of autoregulation. In contrast, in <span class="hlt">lambs</span> two-weeks of age, surgical removal of one SCG resulted in ipsilateral loss of autoregulation during pronounced hypertension. Electrical stimulation of one SCG elicited unilateral increases in cerebral resistance to blood flow in both pre-term and two-week-old <span class="hlt">lambs</span>, indicating functioning neural pathways in the instrumented, anesthetized <span class="hlt">lambs</span>. We conclude cerebral autoregulation is non-functional in preterm <span class="hlt">lambs</span> following cesarean delivery. Adrenergic control of cerebral vascular resistance becomes effective in newborn <span class="hlt">lambs</span> within two-weeks after birth but SCG-dependent autoregulation is essential only during pronounced hypertension, well above the normal range of blood pressure. PMID:24349256</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3750509','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3750509"><span id="translatedtitle">Hereditary lissencephaly and cerebellar hypoplasia in Churra <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2013-01-01</p> <p>Background Lissencephaly is a rare developmental brain disorder in veterinary and human medicine associated with defects in neuronal migration leading to a characteristic marked reduction or absence of the convolutional pattern of the cerebral hemispheres. In many human cases the disease has a genetic basis. In sheep, brain malformations, mainly cerebellar hypoplasia and forms of hydrocephalus, are frequently due to in utero viral infections. Although breed-related malformations of the brain have been described in sheep, breed-related lissencephaly has not been previously recorded in a peer reviewed publication. Results Here we report neuropathological findings in 42 newborn <span class="hlt">lambs</span> from a pure Churra breed flock, with clinical signs of weakness, inability to walk, difficulty in sucking and muscular rigidity observed immediately after birth. All the <span class="hlt">lambs</span> showed near-total agyria with only a rudimentary formation of few sulci and gyri, and a severe cerebellar hypoplasia. On coronal section, the cerebral grey matter was markedly thicker than that of age-matched unaffected <span class="hlt">lambs</span> and the ventricular system was moderately dilated. Histologically, the normal layers of the cerebral cortex were disorganized and, using an immunohistochemical technique against neurofilaments, three layers were identified instead of the six present in normal brains. The hippocampus was also markedly disorganised and the number and size of lobules were reduced in the cerebellum. Heterotopic neurons were present in different areas of the white matter. The remainder of the brain structures appeared normal. The pathological features reported are consistent with the type LCH-b (lissencephaly with cerebellar hypoplasia group b) defined in human medicine. No involvement of pestivirus or bluetongue virus was detected by immunohistochemistry. An analysis of pedigree data was consistent with a monogenic autosomal recessive pattern inheritance. Conclusions The study describes the clinical and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=370823','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=370823"><span id="translatedtitle">Sequential treatments of premature <span class="hlt">lambs</span> with an artificial surfactant and natural surfactant.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ikegami, M; Jobe, A; Jacobs, H; Jones, S J</p> <p>1981-01-01</p> <p>To test an artificial surfactant in vivo, six 120-d gestational age <span class="hlt">lambs</span> were treated at birth with a mixture of a 9:1 M ratio of [14C]dipalmitoyl phosphatidylcholine (DPC) and phosphatidylglycerol at a dose of 100 mg DPC/kg. Nine other <span class="hlt">lambs</span> were not treated. The mean PO2 values of the <span class="hlt">lambs</span> treated with artificial surfactant were 65.7 +/- 11 mm Hg vs. 24.8 +/- 1.6 mm Hg for the untreated <span class="hlt">lambs</span> (P less than 0.001). All <span class="hlt">lambs</span> then were treated with 50 mg/natural surfactant lipid per kg, which promptly improved PO2 in all <span class="hlt">lambs</span>. The PO2 values of those <span class="hlt">lambs</span> previously treated with artificial surfactant remained greater than 100 mm Hg for 2.5 +/- 0.5 h vs. 0.9 +/- 0.3 h for <span class="hlt">lambs</span> untreated with artificial surfactant (P less than 0.01). The pH and PCO2 values were not strikingly different between the two groups of <span class="hlt">lambs</span>. Airway samples taken from <span class="hlt">lambs</span> treated with artificial surfactant before treatment with natural surfactant had minimal surface tensions of 32 +/- 2.9 dyn/cm, whereas the artificial surfactant reisolated from these samples by centrifugation had minimum surface tension of 0 dyn/cm. The minimum surface tension of artificial surfactant was inhibited by fetal lung fluid from the premature <span class="hlt">lambs</span>, whereas the minimum surface tension of natural surfactant was much less sensitive to inhibition. Artificial surfactant did not improve the pressure-volume characteristics of unventilated premature lung, whereas natural surfactant did. The change in specific activity of [14C]DPC following treatment with natural surfactant indicated that approximately 50% of the DPC initially administered was no longer associated with the airways. PMID:6790576</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8585797','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8585797"><span id="translatedtitle">Rumen fermentation and metabolic profile in conventional and gnotobiotic <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bomba, A; Zitnan, R; Koniarová, I; Lauková, A; Sommer, A; Posivák, J; Bucko, V; Pataky, J</p> <p>1995-01-01</p> <p>Observations were carried out of actual acidity, volatile fatty acid (VFA) concentrations, enzyme activity in the rumen, total protein, urea, total lipid and glucose in the serum of conventional (CL) and gnotobiotic <span class="hlt">lambs</span> (GL) in the period of milk nutrition. The inoculum of gnotobiotic <span class="hlt">lambs</span> contained Streptococcus bovis, Prevoxella ruminicola, Butyrivibrio fibrisolvens and Selenomonas ruminantium at a concentration of 1.10(6) each. Throughout the observation period the pH of the rumen contents of gnotobiotic <span class="hlt">lambs</span> ranged within 6.5-6.8 with a significant difference at an age of 7 weeks. Total VFA concentrations in the rumen contents were increased in the CL throughout milk nutrition: the differences at 4 and 5 weeks of age were significant. Total VFA in the conventional <span class="hlt">lambs</span> revealed an increasing tendency between weeks 4 and 7, reaching higher levels at 7 weeks of age (57.1 mmol.l-1), whereas in the gnotobiotic animals the range (24.3-30.1 mmol.l-1) was narrow and the peak occurred at 6 weeks of age. In GL significantly increased molar proportions of acetic acid were observed whereas in CL the molar proportions of propionic acid proved to be significant increased. The molar proportions of butyric and valeric acids were increased in CL but the group differences were not significant. In GL no isoacids were found. Alpha amylase (E.C.3.2.1.1.) activity of the rumen contents was significantly increased in GL between weeks 2 and 6 of age whereas cellulase (endoglucanase E.C.3.2.1.4. and cellobiohydrolase E.C.3.2.1.91.) activity was significantly increased in 4-week-old CL. Over the whole period of milk nutrition no significant differences were observed in urease (E.C.3.5.1.5.) activity of the rumen contents in the examined groups. At 5 weeks of age significantly increased total protein levels were observed in the conventional animals with maximum levels occurring at 4 weeks of age (CL-59.5 g.l-1 GL-55.3 g.l-1). Urea levels in 6-week old conventional <span class="hlt">lambs</span> were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhPro..70..787S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhPro..70..787S"><span id="translatedtitle">The Mode Method as a Framework for Theoretical Studies of Ultrasonic <span class="hlt">Waves</span> Diffraction in Non-homogeneous Layered Structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shkerdin, G.</p> <p></p> <p>Fundamentals of the mode method including orthogonality conditions between different modes and derivations of coupled equations systems for unknown expansion coefficients are given in the paper for the case of 2D isotropic structures. Using the mode method, several concrete problems of ultrasonic <span class="hlt">waves</span> diffraction in non-homogeneous layered structures are presented in the paper such as: Scholte-Stoneley <span class="hlt">wave</span> excitation and conversion at the edge of a liquid loaded plate, interaction of <span class="hlt">Lamb</span> <span class="hlt">waves</span> with delaminations in plates coated by highly absorbing materials and nonlinear modulation of <span class="hlt">Lamb</span> modes by clapping delaminations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004ASAJ..116.2478D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ASAJ..116.2478D"><span id="translatedtitle">Ultrasonic <span class="hlt">wave</span> propagation in cortical bone mimics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dodd, Simon P.; Cunningham, James L.; Miles, Anthony W.; Humphrey, Victor F.; Gheduzzi, Sabina</p> <p>2004-10-01</p> <p>Understanding the velocity and attenuation of ultrasonic <span class="hlt">waves</span> in cortical bone is important for studies of osteoporosis and fractures. In particular, propagation in free- and water-loaded acrylic plates, with a thickness range of around 1-6 mm, has been widely used to mimic cortical bone behavior. A theoretical investigation of <span class="hlt">Lamb</span> mode propagation at 200 kHz in free- and water-loaded acrylic plates revealed a marked difference in the form of their velocity and attenuation dispersion curves as a function of frequency thickness product. In experimental studies, this difference between free and loaded plates is not seen. Over short measurement distances, the results for both free and loaded plates are consistent with previous modeling and experimental studies: for thicker plates (above 3-4 mm), the velocity calculated using the first arrival signal is a lateral <span class="hlt">wave</span> comparable with the longitudinal velocity. As the plate thickness decreases, the velocity approaches the S0 <span class="hlt">Lamb</span> mode value. <span class="hlt">WAVE</span>2000 modeling of the experimental setup agrees with experimental data. The data are also used to test a hypothesis that for thin plates the velocity approaches the corresponding S0 <span class="hlt">Lamb</span> mode velocity at large measurement distances or when different arrival time criteria are used. [Work supported by Action Medical Research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6057517','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6057517"><span id="translatedtitle">Stiochiometry of maltodextrin-binding sites in <span class="hlt">LamB</span>, an outer membrane protein from Escherichia coli</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gehring, K.; Cheng, Chaohsiung; Jap, B.K. ); Nikaido, H. )</p> <p>1991-03-01</p> <p>The authors have directly measured the stoichiometry of maltodextrin-binding sites in <span class="hlt">LamB</span>. Scatchard plots and computer fitting of flow dialysis (rate-of-dialysis) experiments clearly establish three independent binding sites per <span class="hlt">LamB</span> trimer, with a dissociation constant of approximately 60 {mu}M for maltoheptaose. The current model for <span class="hlt">LamB</span>'s function as a specific pore is discussed with respect to the symmetry in <span class="hlt">LamB</span>'s kinetic properties and the implications of their results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=285351','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=285351"><span id="translatedtitle">Effects of diet on carcass quality and consumer taste panel acceptance of intact or castrated hair <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Forty hair-type <span class="hlt">lambs</span> were examined in a 70-d study to determine the effects of gender (castrate; C vs. intact; I) and forage type on carcass traits and sensory acceptability. <span class="hlt">Lambs</span> were procured from a single source in Missouri and one-half were randomly castrated. <span class="hlt">Lambs</span> were randomly assigned to t...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=214896','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=214896"><span id="translatedtitle">Toxoplasma gondii infection in <span class="hlt">lambs</span>: high prevalence of live parasites, and genetic characterisation of T. gondii isolates revealed new genotypes</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Little information is available on the presence of viable Toxoplasma gondii in tissues of <span class="hlt">lambs</span> worldwide. The prevalence of T. gondii was determined in 383 <span class="hlt">lambs</span> (< 1 year old) from Maryland, Virginia, and West Virginia. Hearts of 383 <span class="hlt">lambs</span> were obtained from a slaughter house on the day of killing...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25659525','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25659525"><span id="translatedtitle">Behavioural expression of positive anticipation for food or opportunity to play in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anderson, Claes; Yngvesson, Jenny; Boissy, Alain; Uvnäs-Moberg, Kerstin; Lidfors, Lena</p> <p>2015-04-01</p> <p>Anticipatory behaviours may serve a useful tool in studying positive emotional states in animals. This study aimed to investigate if <span class="hlt">lambs</span> express anticipatory behaviours for opportunities to play or a food reward and if these behaviours would differ depending on the anticipated event. Forty-two male <span class="hlt">lambs</span> were allocated into three treatment groups (control, play, food). Play and food <span class="hlt">lambs</span> were conditioned to anticipate play or food in a holding pen for three minutes prior to accessing a reward arena containing toy objects or concentrate, respectively. Control <span class="hlt">lambs</span> returned to their home pen following three minutes in the holding pen. Compared to the control <span class="hlt">lambs</span>, both play and food <span class="hlt">lambs</span> differed in several behaviours frequencies and durations, e.g. by an increased frequency of behavioural transitions and duration of walking. Following these observations, food <span class="hlt">lambs</span> received the toy objects when entering the reward arena. The subsequent session in the holding pen resulted in a decrease in number of behavioural transitions, time spent walking and an increase in time standing still. In conclusion, anticipating a positive event resulted in differences in behaviour compared to a control group, and these behaviours are affected when the anticipated event does not fit with the <span class="hlt">lambs</span>' expectations. PMID:25659525</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=135208','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=135208"><span id="translatedtitle">ESTIMATION OF GENETIC PARAMETERS OF <span class="hlt">LAMB</span> MORTALITY USING DISCRETE SURVIVAL ANALYSIS</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p><span class="hlt">Lamb</span> mortality from a composite population at the U.S. Meat Animal Research Center was studied using descrete time survival analysis since the actual time of mortality may be unavailable but information about a particular interval is available. Mortality records from 8,642 <span class="hlt">lambs</span> were separated acco...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=139278','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=139278"><span id="translatedtitle">DISCRETE TIME SURVIVAL ANALYSIS OF <span class="hlt">LAMB</span> MORTALITY IN A TERMINAL SIRE COMPOSITE POPULATION</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Mortality records during the first year of life of 8,642 <span class="hlt">lambs</span> from a composite population at the U.S. Meat Animal Research Center were studied using discrete survival analyses. <span class="hlt">Lamb</span> mortality was studied across periods from birth to weaning, birth to 365 d of age and weaning to 365 d of age. Animal...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=202182','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=202182"><span id="translatedtitle">Pasture-raised Katahdin and Katahdin crossbred <span class="hlt">lambs</span>: growth and parasite resistance</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Katahdin ewes were mated to Dorper, Texel, Suffolk or Katahdin rams (3 rams/breed; 8-10 ewes each) to compare growth performance and parasite resistance of the crossbred <span class="hlt">lambs</span>. <span class="hlt">Lamb</span> BW was measured at birth (=d0), and then every 30d to d210 (adjusted). Fecal egg counts (FEC) were determined at d60 ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=265813','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=265813"><span id="translatedtitle">Correlations between measures of feed efficiency and feedlot return for F1 <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Objective estimates of feedlot return for progeny of terminal-sire breeds of sheep are needed to improve <span class="hlt">lamb</span> profitability. Thus, we used recent economic data to determine the effects of terminal-sire breed on returns of F1 <span class="hlt">lambs</span>. Annually for 3 yr, Columbia, USMARC Composite, Suffolk, and Texel ra...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=292406','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=292406"><span id="translatedtitle">Genetic evaluation of the probability of <span class="hlt">lambing</span> in yearling Targhee ewes</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The objective of this study was to determine the additive genetic control of <span class="hlt">lambing</span> percentage in yearling Targhee ewes. The records of 3,103 ewe <span class="hlt">lambs</span> born from 1989 to 2011 and mated at approximately 7.5 mo of age were analyzed. Records included sire, dam, weaning weight, breeding pen, age of dam...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2603654','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2603654"><span id="translatedtitle">Adverse outcome of using tilmicosin in a <span class="hlt">lamb</span> with multiple ventricular septal defects</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Christodoulopoulos, Georgios</p> <p>2009-01-01</p> <p>A 15-day-old, 6.08 kg, <span class="hlt">lamb</span> was injected subcutaneously with tilmicosin 15 mg/kg body weight. Approximately 15 min later, the <span class="hlt">lamb</span> died. During necropsy, the heart was found to have multiple ventricular septal defects. Death was attributed to sudden heart failure due to the cardiac effects of tilmicosin in a heart having congenital defects. PMID:19337615</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Sheep&pg=7&id=ED265327','ERIC'); return false;" href="http://eric.ed.gov/?q=Sheep&pg=7&id=ED265327"><span id="translatedtitle">Sheep Stockmanship (<span class="hlt">Lambing</span>). Youth Training Scheme. Core Exemplar Work Based Project.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Further Education Staff Coll., Blagdon (England).</p> <p></p> <p>This trainer's guide is intended to assist supervisors of work-based career training projects in helping students gather and record information about sheep breeding, learn about treatment of diseases, prepare the <span class="hlt">lambing</span> area, and assist with the aftercare of <span class="hlt">lambs</span> and ewes. The guide is one in a series of core curriculum modules that is intended…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title9-vol2/pdf/CFR-2012-title9-vol2-sec311-28.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title9-vol2/pdf/CFR-2012-title9-vol2-sec311-28.pdf"><span id="translatedtitle">9 CFR 311.28 - Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. 311.28 Section 311.28 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PARTS § 311.28 Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. Carcasses of young calves,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title9-vol2/pdf/CFR-2014-title9-vol2-sec311-28.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title9-vol2/pdf/CFR-2014-title9-vol2-sec311-28.pdf"><span id="translatedtitle">9 CFR 311.28 - Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. 311.28 Section 311.28 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PARTS § 311.28 Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. Carcasses of young calves,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title9-vol2/pdf/CFR-2011-title9-vol2-sec311-28.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title9-vol2/pdf/CFR-2011-title9-vol2-sec311-28.pdf"><span id="translatedtitle">9 CFR 311.28 - Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. 311.28 Section 311.28 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PARTS § 311.28 Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. Carcasses of young calves,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title9-vol2/pdf/CFR-2013-title9-vol2-sec311-28.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title9-vol2/pdf/CFR-2013-title9-vol2-sec311-28.pdf"><span id="translatedtitle">9 CFR 311.28 - Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. 311.28 Section 311.28 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PARTS § 311.28 Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. Carcasses of young calves,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title9-vol2/pdf/CFR-2010-title9-vol2-sec311-28.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title9-vol2/pdf/CFR-2010-title9-vol2-sec311-28.pdf"><span id="translatedtitle">9 CFR 311.28 - Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. 311.28 Section 311.28 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PARTS § 311.28 Carcasses of young calves, pigs, kids, <span class="hlt">lambs</span>, and foals. Carcasses of young calves,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16727011','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16727011"><span id="translatedtitle">Age at puberty, fertility and litter size of ewe <span class="hlt">lambs</span> reared under different photoregimens.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ainsworth, L; Heaney, D P; Shrestha, J N</p> <p>1991-09-01</p> <p>Age at puberty, fertility and litter size of ewe <span class="hlt">lambs</span> of synthetic sire and dam strains raised under different photoregimens were determined. The <span class="hlt">lambs</span> were bred during January, May or September at 30 to 32 weeks of age. Irrespective of birth date, the <span class="hlt">lambs</span> were reared under continuous light from birth to 5 weeks of age. From 5 to 20 weeks of age, they were kept under 16 hours of light dairy (16L:8D; Treatment A), 8 hours of light daily (8L:16D; Treatment B), or a split photoperiod of 8 hours total light daily (7L:9D:1L:7D; Treatment C). Subsequently, all <span class="hlt">lambs</span> were exposed to 9 hours of light daily until after breeding. <span class="hlt">Lambs</span> were exposed to rams for two estrous periods after treatment with fluorogestone acetate-impregnated intravaginal sponges and pregnant mares' serum gonadotropin (PMSG) to induce synchronized estrus. Although the age at puberty (174 days) was similar among treatments, the incidence of puberty prior to progestagen sponge treatment was higher (approximately 50%) for <span class="hlt">lambs</span> reared under Treatments A and C than under Treatment B. Fertility and litter size of <span class="hlt">lambs</span> were not influenced by the previous photoperiod history or by sexual maturity, i.e., puberal or prepuberal, at the start of the sponge treatment. However, strain, age and weight of <span class="hlt">lambs</span> at breeding influenced significantly the reproductive outcome. PMID:16727011</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=290880','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=290880"><span id="translatedtitle">Sericea Lespedeza as an Aid in the Control of Coccidiosis in <span class="hlt">Lambs</span></span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>We have determined that feeding sericea lespedeza leaf meal (SL) can effectively control coccidiosis in <span class="hlt">lambs</span>. In Exp. 1, naturally infected <span class="hlt">lambs</span> (n = 76) were weaned (103 days of age) in May and fed 2% of body weight daily of alfalfa pellets (control) or SL with or without Corrid added to drinkin...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26048172','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26048172"><span id="translatedtitle">Finite element simulation of core inspection in helicopter rotor blades using guided <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chakrapani, Sunil Kishore; Barnard, Daniel; Dayal, Vinay</p> <p>2015-09-01</p> <p>This paper extends the work presented earlier on inspection of helicopter rotor blades using guided <span class="hlt">Lamb</span> modes by focusing on inspecting the spar-core bond. In particular, this research focuses on structures which employ high stiffness, high density core materials. <span class="hlt">Wave</span> propagation in such structures deviate from the generic <span class="hlt">Lamb</span> <span class="hlt">wave</span> propagation in sandwich panels. To understand the various mode conversions, finite element models of a generalized helicopter rotor blade were created and subjected to transient analysis using a commercial finite element code; ANSYS. Numerical simulations showed that a <span class="hlt">Lamb</span> <span class="hlt">wave</span> excited in the spar section of the blade gets converted into Rayleigh <span class="hlt">wave</span> which travels across the spar-core section and mode converts back into <span class="hlt">Lamb</span> <span class="hlt">wave</span>. Dispersion of Rayleigh <span class="hlt">waves</span> in multi-layered half-space was also explored. Damage was modeled in the form of a notch in the core section to simulate a cracked core, and delamination was modeled between the spar and core material to simulate spar-core disbond. Mode conversions under these damaged conditions were examined numerically. The numerical models help in assessing the difficulty of using nondestructive evaluation for complex structures and also highlight the physics behind the mode conversions which occur at various discontinuities. PMID:26048172</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27136018','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27136018"><span id="translatedtitle">Changes in concentrations of trace minerals in <span class="hlt">lambs</span> fed sericea lespedeza leaf meal pellets with or without dietary sodium molybdate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Acharya, M; Burke, J M; Coffey, K P; Kegley, E B; Miller, J E; Smyth, E; Welborn, M G; Terrill, T H; Mosjidis, J A; Rosenkrans, C</p> <p>2016-04-01</p> <p>Prolonged feeding of sericea lespedeza (SL) previously led to reduced serum concentrations of Mo, a cofactor in an enzyme complex that may be involved in weight gain. The current objective was to determine the effect of Mo supplementation on changes in serum, fecal, urine, and liver concentrations of trace minerals in <span class="hlt">lambs</span> fed SL leaf meal pellets. Thirty ram <span class="hlt">lambs</span> weaned in May (84 ± 1.5 d of age and 27 ± 1.1 kg; D 0) were blocked by BW, breed type (full or three-fourths Katahdin), and EBV of parasite resistance and randomly assigned to be fed 900 g/d of an alfalfa-based supplement (CON; = 10) or a SL-based supplement ( = 20) for 103 d. Supplements were formulated to be isonitrogenous and isocaloric and to meet trace mineral requirements. Within the SL group, individual <span class="hlt">lambs</span> were administered either 5 mL water or 5 mL of water with 163.3 mg of sodium molybdate (SLMO). Serum was collected on d 28, 56, and 104; a liver sample was collected by biopsy on d 104 to determine concentrations of trace minerals. Data were analyzed using a mixed model and orthogonal contrasts. Serum concentrations of Mo increased in response to the drench and were greatest in SLMO <span class="hlt">lambs</span> and then CON <span class="hlt">lambs</span> and lowest in SL <span class="hlt">lambs</span> ( < 0.001). Concentrations of Mo in the liver ( < 0.001) were similar between CON and SLMO <span class="hlt">lambs</span> and were lower in SL <span class="hlt">lambs</span> than other groups. Serum ( < 0.001) and liver ( = 0.013) concentrations of zinc (Zn) were reduced in both SL and SLMO <span class="hlt">lambs</span> compared with CON <span class="hlt">lambs</span>. Serum concentrations of cobalt (Co) increased in CON <span class="hlt">lambs</span> compared with SL and SLMO <span class="hlt">lambs</span> between d 0 and 56 but were similar on d 104 (diet × day, < 0.005) as with concentrations in the liver. Serum and liver concentrations of copper (Cu) were greatest ( < 0.001 and < 0.001, respectively) in CON <span class="hlt">lambs</span> followed by SL <span class="hlt">lambs</span> and then SLMO <span class="hlt">lambs</span>. Serum concentrations of selenium (Se) tended ( = 0.10) to be reduced in SL <span class="hlt">lambs</span> compared with CON and SLMO <span class="hlt">lambs</span>, but concentrations in the liver were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27065149','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27065149"><span id="translatedtitle">The effects of poor maternal nutrition during gestation on postnatal growth and development of <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoffman, M L; Peck, K N; Forella, M E; Fox, A R; Govoni, K E; Zinn, S A</p> <p>2016-02-01</p> <p>Poor maternal nutrition can affect the growth and development of offspring, which may lead to negative consequences in adult life. We hypothesized that <span class="hlt">lambs</span> born to poorly nourished ewes would have reduced growth rate and increased fat deposition, with corresponding changes in the somatotropic axis, and leptin, insulin and glucose concentrations. Ewes ( = 36; 12/treatment) were assigned 1 of 3 diets; 100% (CON), 60% (RES), or 140% (OVER) of NRC requirements for TDN at d 31 of gestation until parturition. One <span class="hlt">lamb</span> per ewe ( = 35; 11 to 12 per treatment) was used; 18 <span class="hlt">lambs</span> were euthanized at d 1, and 17 were fed the same diet for 3 mo and then euthanized. <span class="hlt">Lamb</span> crown rump length (CRL), heart girth, BW, and BCS were measured, and blood samples were collected at d 1 and then at weekly intervals until euthanasia. Averaged from d 1 until 3 mo, <span class="hlt">lambs</span> from OVER ewes were larger compared with <span class="hlt">lambs</span> born to CON ewes (BW [16.97 vs. 15.44 kg ± 0.60; = 0.09], ADG [0.23 vs. 0.21 ± 0.01 kg/d; = 0.01], and CRL [68.9 vs. 66.1 ± 0.80 cm; = 0.02]). On a BW basis, heart weight from <span class="hlt">lambs</span> from RES (0.18 kg ± 0.03; = 0.03) ewes was greater than that of CON <span class="hlt">lambs</span> (0.15 kg ± 0.03). Backfat thickness was reduced in RES <span class="hlt">lambs</span> (0.11 ± 0.06; ≤ 0.04) compared with CON (0.20 ± 0.06) and OVER (0.26 ± 0.06) <span class="hlt">lambs</span>. Concentrations of IGF-I at 3 mo and IGFBP-3 from weaning (d 56 of age) to 3 mo of age tended to be greater ( ≤ 0.06) in OVER <span class="hlt">lambs</span> (334 ± 66 ng/mL and 175 ± 11 arbitrary units [AU], respectively) than CON <span class="hlt">lambs</span> (149 ± 66 ng/mL and 140 ± 11 AU, respectively). At 3 mo, leptin was greater in OVER <span class="hlt">lambs</span> compared with RES <span class="hlt">lambs</span> (1.24 vs. 0.78 ± 0.13 ng/mL; < 0.05). Over time, average insulin concentrations were greater in OVER and RES <span class="hlt">lambs</span> than CON <span class="hlt">lambs</span> (0.49 and 0.49 vs. 0.33 ± 0.05 ng/mL; ≤ 0.02). However, concentrations of GH, IGFBP-2, glucose, triglycerides, and total cholesterol were not different ( > 0.10) between treatment groups. During in vivo glucose tolerance</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22444384','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22444384"><span id="translatedtitle">Discrimination of pasture-fed <span class="hlt">lambs</span> from <span class="hlt">lambs</span> fed dehydrated alfalfa indoors using different compounds measured in the fat, meat and plasma.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prache, S; Kondjoyan, N; Delfosse, O; Chauveau-Duriot, B; Andueza, D; Cornu, A</p> <p>2009-04-01</p> <p>The last decade has seen important developments in the use of carotenoid pigments to authenticate pasture-feeding in ruminants. However, dehydrated alfalfa is sometimes incorporated in grain-based concentrates fed to stall-raised <span class="hlt">lambs</span>, which may affect the reliability of the pasture-feeding authentication methods based on carotenoids in plasma and fat, due to significant residual carotenoid levels post-dehydration. The aim of this study was to examine whether other compounds can give additional information to authenticate diet and discriminate pasture-fed <span class="hlt">lambs</span> from <span class="hlt">lambs</span> fed high levels of alfalfa indoors. Two feeding treatments were compared: pasture-feeding (P) v. stall-feeding with dehydrated alfalfa (A). Each treatment group consisted of seven male Romanov × Berrichon <span class="hlt">lambs</span>. Pasture-fed (P) <span class="hlt">lambs</span> grazed a permanent graminaceae-rich pasture maintained at a leafy, green stage, offered ad libitum; they received no supplementation at pasture. A-group <span class="hlt">lambs</span> were individually penned and fed dehydrated alfalfa and straw; their feed level was adjusted to achieve a similar growth pattern as for P-group <span class="hlt">lambs</span>. Plasma carotenoid concentration was measured at slaughter by spectrophotometry. The reflectance spectrum of perirenal and subcutaneous caudal fat was measured at 24-h post mortem and used to calculate an index (absolute value of the mean integral (AVMI)) quantifying light absorption by carotenoid pigments present in the fat. The nitrogen (N) stable isotopes ratio (δ15N) in both feed and longissimus dorsi muscle was measured by isotopes ratio mass spectrometry (IRMS). Volatile compounds were analyzed in perirenal fat for five randomly chosen <span class="hlt">lambs</span> per treatment, using dynamic headspace-gas chromatography-mass spectrometry. Plasma carotenoid concentration and AVMI of the fat did not differ significantly between P- and A-group <span class="hlt">lambs</span>, but there were significant between-treatment differences in meat δ15N values and in the terpene profiles of perirenal fat. A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/2235134','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/2235134"><span id="translatedtitle">Regional cerebral blood flow after hemorrhagic hypotension in the preterm, near-term, and newborn <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Szymonowicz, W; Walker, A M; Yu, V Y; Stewart, M L; Cannata, J; Cussen, L</p> <p>1990-10-01</p> <p>Developmental changes in regional cerebral blood flow (CBF) responses to hemorrhagic hypotension during normoxia and normocapnia were determined using radioactively labeled microspheres to measure flow to the cortex, brainstem, cerebellum, white matter, caudate nucleus, and choroid plexus in three groups of chronically catheterized <span class="hlt">lambs</span>: 90- to 100-d preterm fetal <span class="hlt">lambs</span> (n = 9); 125- to 136-d near-term fetal <span class="hlt">lambs</span> (n = 9); and newborn <span class="hlt">lambs</span> 5- to 35-d-old (n = 8). Heart rate, central venous pressure, and arterial blood pressure were monitored continuously and arterial blood gas tensions, pH, Hb, and oxygen saturation together with regional CBF were measured periodically. Hemorrhagic hypotension produced a mean decrease in arterial blood pressure of 27 +/- 4, 23 +/- 2, and 41 +/- 4% in the three groups, respectively, whereas reinfusion of the <span class="hlt">lamb</span>'s blood resulted in a return to control blood pressure within 3% in all three groups. In the pre-term fetal <span class="hlt">lamb</span>, CBF decreased significantly in all regions during hypotension. In the near-term fetal <span class="hlt">lamb</span>, only blood flow to the cortex decreased significantly during hypotension. In the newborn <span class="hlt">lamb</span>, only the choroid plexus demonstrated a significant decrease in blood flow during hypotension. The lower limit of regional CBF autoregulation was identical to the resting mean arterial pressure in fetal life but significantly lower in newborn <span class="hlt">lambs</span>. These experiments demonstrate for the first time that vulnerability to hypotension decreases with increasing maturity and that the brainstem, the phylogenetically oldest region of the brain, is the least vulnerable to the effects of hypotension at any age in the <span class="hlt">lamb</span> model. PMID:2235134</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24524327','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24524327"><span id="translatedtitle">Effect of milk replacer and rumen inert fat on growth and reproduction of Malpura ram <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kumar, D; Bhatt, R S; Karim, S A; Naqvi, S M K</p> <p>2014-04-01</p> <p>The objective of this study was to assess the effects of milk replacer and rumen inert fat on growth, testicular development, puberty, semen production and sperm motion characteristics of ram <span class="hlt">lambs</span> reared under intensive management in semi-arid climatic conditions. Seven-day-old male <span class="hlt">lambs</span> of Malpura breed (n=20) were divided equally into two groups. Up to weaning, the <span class="hlt">lambs</span> in G1 group (control) were fed concentrate, green khejri (Prosopis cineraria) leaves and cowpea (Vigna unguiculata) hay along with suckling of dams, whereas <span class="hlt">lambs</span> in G2 group were fed reconstituted milk at 17 g/<span class="hlt">lamb</span> per day for the 1st week and at 34 g/<span class="hlt">lamb</span> per day from 2nd week in addition to the feed inputs given in G1. During post weaning, <span class="hlt">lambs</span> in the G1 group were given control concentrate, whereas in G2 the control concentrate supplemented with 40 g rumen inert fat per kg of feed was offered along with dry pala (Zizyphus nummularia) and ardu (Ailanthus excelsa) leaves. BWs of <span class="hlt">lambs</span> were recorded weekly up to 6 months of age. Ram <span class="hlt">lambs</span> of both the groups were trained for semen collection at a weekly interval from the age of 5 months and simultaneously testicular measurements were recorded fortnightly. The feeding of milk replacer and rumen inert fat had positive (P<0.05) effects on BW, testicular length, testicular volume, semen volume, sperm concentration, mass motility, % motility, % rapid, medium or slow motile spermatozoa. However, no significant effect was observed on testicular breadth, scrotal circumference, age of puberty, sperm velocities and other CASA-derived parameters. The results of this study indicate that higher plane of nutrition in the form of milk-replacer feeding during preweaning and rumen inert fat-supplemented feed during the postweaning period to growing ram <span class="hlt">lambs</span> enhances their growth, testicular development and semen quality. PMID:24524327</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25257191','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25257191"><span id="translatedtitle">Laminin gene <span class="hlt">LAMB</span>4 is somatically mutated and expressionally altered in gastric and colorectal cancers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Choi, Mi Ryoung; An, Chang Hyeok; Yoo, Nam Jin; Lee, Sug Hyung</p> <p>2015-01-01</p> <p>Laminins are important in tumor invasion and metastasis as well as in maintenance of normal epithelial cell structures. However, mutation status of laminin chain-encoding genes remains unknown in cancers. Aim of this study was to explore whether laminin chain genes are mutated and expressionally altered in gastric (GC) and colorectal cancers (CRC). In a public database, we found that laminin chain genes LAMA1, LAMA3, <span class="hlt">LAMB</span>1 and <span class="hlt">LAMB</span>4 had mononucleotide repeats in the coding sequences that might be mutation targets in the cancers with microsatellite instability (MSI). We analyzed the genes in 88 GC and 139 CRC [high MSI (MSI-H) or stable MSI/low MSI (MSS/MSI-L)] by single strand conformation polymorphism analysis and DNA sequencing. In the present study, we found <span class="hlt">LAMB</span>4 (11.8% of GC and 7.6% of CRC with MSI-H), LAMA3 (2.9% of GC and 2.5 of CRC with MSI-H), LAMA1 (5.9% of GC with MSI-H) and <span class="hlt">LAMB</span>1 frameshift mutations (1.3% of CRC with MSI-H). These mutations were not found in MSS/MSI-L (0/114). We also analyzed <span class="hlt">LAMB</span>4 expression in GC and CRC by immunohistochemistry. Loss of <span class="hlt">LAMB</span>4 expression was identified in 17-32% of the GC and CRC. Of note, the loss expression was more common in the cancers with <span class="hlt">LAMB</span>4 mutation or those with MSI-H. Our data show that frameshift mutations of LAMA1, LAMA3, <span class="hlt">LAMB</span>1 and <span class="hlt">LAMB</span>4, and loss of <span class="hlt">LAMB</span>4 may be features of GC and CRC with MSI-H. PMID:25257191</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4340872','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4340872"><span id="translatedtitle">Do <span class="hlt">Lambs</span> Perceive Regular Human Stroking as Pleasant? Behavior and Heart Rate Variability Analyses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Coulon, Marjorie; Nowak, Raymond; Peyrat, Julie; Chandèze, Hervé; Boissy, Alain; Boivin, Xavier</p> <p>2015-01-01</p> <p>Stroking by humans is beneficial to the human-animal relationship and improves welfare in many species that express intraspecific allogrooming, but very few studies have looked at species like sheep that do not express such contact except around parturition. This study investigated the way <span class="hlt">lambs</span> perceive regular human tactile contact using behavioral and physiological responses. Twenty-four <span class="hlt">lambs</span> were reared and bucket-fed in groups of four. All were stroked daily by their familiar caregiver. At 8 weeks of age, the <span class="hlt">lambs</span> were individually tested in their home pen but in a 1×1m open-barred pen after a 15h period of habituation to physical separation from peers while remaining in visual and auditory contact. Half of the <span class="hlt">lambs</span> received stroking by their caregiver for 8min and half were exposed to their caregiver’s immobile presence. Heart rate and heart rate variability were recorded and analyzed by 2-min slots over the same interval based on three measures: mean heart rate value (HR), root mean square of successive differences (RMSSD) and standard deviation of all intervals measured between consecutive sinus beats (SDNN). Behavioral responses (ear postures of the <span class="hlt">lamb</span> and time spent in contact with the familiar caregiver, on the knees of the familiar caregiver, and moving) were recorded throughout the test. <span class="hlt">Lamb</span> HR decreased continuously while in the presence of their caregiver. <span class="hlt">Lambs</span> being stroked showed slower HR and higher RMSSD which reflected positive emotional states compared to <span class="hlt">lambs</span> left unstroked. All behavioral variables were highly correlated with the main component axis of the PCA analyses: the more the animals stayed in contact with their caregiver, the less they moved and the more their ears were hanging. This first component clearly differentiates <span class="hlt">lambs</span> being stroked or not. Behavioral and physiological observations support the hypothesis that gentle physical contact with the caregiver is perceived positively by <span class="hlt">lambs</span>. PMID:25714604</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25714604','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25714604"><span id="translatedtitle">Do <span class="hlt">lambs</span> perceive regular human stroking as pleasant? Behavior and heart rate variability analyses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Coulon, Marjorie; Nowak, Raymond; Peyrat, Julie; Chandèze, Hervé; Boissy, Alain; Boivin, Xavier</p> <p>2015-01-01</p> <p>Stroking by humans is beneficial to the human-animal relationship and improves welfare in many species that express intraspecific allogrooming, but very few studies have looked at species like sheep that do not express such contact except around parturition. This study investigated the way <span class="hlt">lambs</span> perceive regular human tactile contact using behavioral and physiological responses. Twenty-four <span class="hlt">lambs</span> were reared and bucket-fed in groups of four. All were stroked daily by their familiar caregiver. At 8 weeks of age, the <span class="hlt">lambs</span> were individually tested in their home pen but in a 1×1m open-barred pen after a 15 h period of habituation to physical separation from peers while remaining in visual and auditory contact. Half of the <span class="hlt">lambs</span> received stroking by their caregiver for 8 min and half were exposed to their caregiver's immobile presence. Heart rate and heart rate variability were recorded and analyzed by 2-min slots over the same interval based on three measures: mean heart rate value (HR), root mean square of successive differences (RMSSD) and standard deviation of all intervals measured between consecutive sinus beats (SDNN). Behavioral responses (ear postures of the <span class="hlt">lamb</span> and time spent in contact with the familiar caregiver, on the knees of the familiar caregiver, and moving) were recorded throughout the test. <span class="hlt">Lamb</span> HR decreased continuously while in the presence of their caregiver. <span class="hlt">Lambs</span> being stroked showed slower HR and higher RMSSD which reflected positive emotional states compared to <span class="hlt">lambs</span> left unstroked. All behavioral variables were highly correlated with the main component axis of the PCA analyses: the more the animals stayed in contact with their caregiver, the less they moved and the more their ears were hanging. This first component clearly differentiates <span class="hlt">lambs</span> being stroked or not. Behavioral and physiological observations support the hypothesis that gentle physical contact with the caregiver is perceived positively by <span class="hlt">lambs</span>. PMID:25714604</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AIPC..564...13K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AIPC..564...13K"><span id="translatedtitle">Towards a <span class="hlt">Lamb</span> shift measurement in muonic hydrogen</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kottmann, F.; Biraben, F.; Conde, C. A. N.; Donche-Gay, C.; Hänsch, T. W.; Hartmann, F. J.; Hauser, P.; Hughes, V. W.; Huot, O.; Indelicato, P.; Knowles, P.; Liu, Y.-W.; Markushin, V. E.; Mulhauser, F.; Nez, F.; Pohl, R.; Rabinowitz, P.; dos Santos, J. M. F.; Schaller, L. A.; Schneuwly, H.; Schott, W.; Taqqu, D.; Veloso, J. F. C. A.</p> <p>2001-04-01</p> <p>A measurement of the 2S <span class="hlt">Lamb</span> shift (2S-2P energy difference) in muonic hydrogen (μ-p) is being prepared at the Paul Scherrer Institute (PSI). The goal of the experiment is to measure the <span class="hlt">Lamb</span> shift with 30 ppm precision and to deduce the root mean square (rms) proton charge radius with 10-3 relative accuracy, 20 times more precise than presently known. The experiment is based on the availability of long-lived metastable muonic hydrogen atoms in the 2S state which has been investigated in a recent series of experiments at PSI. From the low-energy part of the initial kinetic energy distribution of μp(2S) atoms we determined the fraction of long-lived μp(2S) to be ˜1.5% for H2 gas pressures between 1 and 64 hPa. Another analysis involving μp(1S) with a kinetic energy of 0.9 keV originating from quenching of thermalized μp(2S) via the resonant process μp(2S)+H2→{[(ppμ)+]*pee}*→μp(1S)+p+…+2 keV gives the same result. This is the first direct observation of long-lived μp(2S) atoms. The realization of the μp <span class="hlt">Lamb</span> shift experiment involves a new low-energy negative muon beam with entrance detectors for keV-muons, a xenon gas-proportional-scintillation-chamber (GPSC) read out by a microstrip-gas-chamber (MSGC) for the detection of 2 keV X-rays, and a randomly triggered 3-stage laser system providing 0.5 mJ, 7 ns laser pulses at 6.02 μm wavelength.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27014211','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27014211"><span id="translatedtitle">Co-housing of Rift Valley Fever Virus Infected <span class="hlt">Lambs</span> with Immunocompetent or Immunosuppressed <span class="hlt">Lambs</span> Does Not Result in Virus Transmission.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wichgers Schreur, Paul J; van Keulen, Lucien; Kant, Jet; Oreshkova, Nadia; Moormann, Rob J M; Kortekaas, Jeroen</p> <p>2016-01-01</p> <p>Rift Valley fever virus (RVFV) is transmitted among susceptible animals by mosquito vectors. Although the virus can be isolated from nasal and oral swabs of infected animals and is known to be highly infectious when administered experimentally via oral or respiratory route, horizontal transmission of the virus is only sporadically reported in literature. We considered that immunosuppression resulting from stressful conditions in the field may increase the susceptibility to horizontally transmitted RVFV. Additionally, we reasoned that horizontal transmission may induce immune responses that could affect the susceptibility of contact-exposed animals to subsequent infection via mosquito vectors. To address these two hypotheses, viremic <span class="hlt">lambs</span> were brought into contact with sentinel <span class="hlt">lambs</span>. One group of sentinel <span class="hlt">lambs</span> was treated with the immunosuppressive synthetic glucocorticosteroid dexamethasone and monitored for signs of disease and presence of virus in the blood and target organs. Another group of contact-exposed sentinel <span class="hlt">lambs</span> remained untreated for three weeks and was subsequently challenged with RVFV. We found that none of the dexamethasone-treated contact-exposed <span class="hlt">lambs</span> developed detectable viremia, antibody responses or significant increases in cytokine mRNA levels. Susceptibility of immunocompetent <span class="hlt">lambs</span> to RVFV infection was not influenced by previous contact-exposure. Our results are discussed in light of previous findings. PMID:27014211</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4779905','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4779905"><span id="translatedtitle">Co-housing of Rift Valley Fever Virus Infected <span class="hlt">Lambs</span> with Immunocompetent or Immunosuppressed <span class="hlt">Lambs</span> Does Not Result in Virus Transmission</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wichgers Schreur, Paul J.; van Keulen, Lucien; Kant, Jet; Oreshkova, Nadia; Moormann, Rob J. M.; Kortekaas, Jeroen</p> <p>2016-01-01</p> <p>Rift Valley fever virus (RVFV) is transmitted among susceptible animals by mosquito vectors. Although the virus can be isolated from nasal and oral swabs of infected animals and is known to be highly infectious when administered experimentally via oral or respiratory route, horizontal transmission of the virus is only sporadically reported in literature. We considered that immunosuppression resulting from stressful conditions in the field may increase the susceptibility to horizontally transmitted RVFV. Additionally, we reasoned that horizontal transmission may induce immune responses that could affect the susceptibility of contact-exposed animals to subsequent infection via mosquito vectors. To address these two hypotheses, viremic <span class="hlt">lambs</span> were brought into contact with sentinel <span class="hlt">lambs</span>. One group of sentinel <span class="hlt">lambs</span> was treated with the immunosuppressive synthetic glucocorticosteroid dexamethasone and monitored for signs of disease and presence of virus in the blood and target organs. Another group of contact-exposed sentinel <span class="hlt">lambs</span> remained untreated for three weeks and was subsequently challenged with RVFV. We found that none of the dexamethasone-treated contact-exposed <span class="hlt">lambs</span> developed detectable viremia, antibody responses or significant increases in cytokine mRNA levels. Susceptibility of immunocompetent <span class="hlt">lambs</span> to RVFV infection was not influenced by previous contact-exposure. Our results are discussed in light of previous findings. PMID:27014211</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4867043','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4867043"><span id="translatedtitle">Patent ductus arteriosus in a <span class="hlt">lamb</span>: A case report</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jafari Dehkordi, Afshin; Hoseini, Farzaneh</p> <p>2016-01-01</p> <p>Patent ductus arteriosus (PDA) is a persistent patency of a vessel normally present in the fetus that connects the pulmonary arterial system to the aorta. The ductus arteriosus fails to close at birth when breathing commences and placental blood circulation is removed. Closure of the ductus arteriosus arises in response to decline pulmonary vascular resistance and increased systemic vascular resistance. This report describes a case of PDA in a two-month-old male <span class="hlt">lamb</span> with clinical signs of machinery murmur, tachycardia, increase respiratory rate, weakness and ill thrift. Echocardiographic examination and necropsy finding confirmed PDA. PMID:27226893</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2804801','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2804801"><span id="translatedtitle">Estrogen Receptor Immunoreactivity in Late-Gestation Fetal <span class="hlt">Lambs</span>1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gorton, Lori M.; Mahoney, Megan M.; Magorien, Julie E.; Lee, Theresa M.; Wood, Ruth I.</p> <p>2009-01-01</p> <p>Prenatal androgens masculinize postnatal reproductive neuroendocrine function and behavior in sheep. Testosterone treatment of pregnant ewes during midgestation masculinizes sexual behavior and luteinizing hormone secretion in female <span class="hlt">lambs</span>, presumably in part via aromatization and estrogen receptor (ESR) binding in the brain. We hypothesized that male and female sheep also differ in the number and distribution of ESR-containing neurons. If so, ESR expression should be sensitive to prenatal hormones delivered exogenously or in situ. ESR alpha (ESR1) was compared by immunocytochemistry in male and female <span class="hlt">lambs</span> at the end of gestation, as well as in fetal females exposed prenatally to testosterone or dihydrotestosterone. ESR1-positive neurons were abundant in the posteromedial bed nucleus of the stria terminalis (BSTpm), medial preoptic area (MPOA), posterior medial amygdaloid nucleus (MeP), amygdalohippocampal area (AHi), ventromedial hypothalamic nuclei (VMH), and arcuate hypothalamic nuclei (ARC). In females, the ARC had the largest number of stained cells (mean ± SEM, 475.6 ± 57.4 cells/0.173 mm2), while staining intensity was greatest in the MPOA (mean ± SEM gray level, 31.3 ± 5.3). The mean ± SEM integrated gray level (IGL) was high in the ARC (0.63 ± 0.13) and in the MPOA (0.51 ± 0.08). The mean ± SEM IGL was low in the MeP (0.31 ± 0.10) and in the BSTpm (0.21 ± 0.06), while it was intermediate in the AHi (0.36 ± 0.10) and in the VMH (0.37 ± 0.07). ESR immunostaining was not significantly different in male and female fetal <span class="hlt">lambs</span>, nor in females fetuses exposed prenatally to androgens (P > 0.05). However, ESR1 staining was significantly increased in the ARC, MPOA, and AHi of adult rams vs. adult ewes. These results suggest that brain ESR immunoreactivity in fetal <span class="hlt">lambs</span> is unlikely to account for postnatal sex differences in reproductive function. Instead, sex differences in ESR emerge postnatally. PMID:19164175</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25293709','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25293709"><span id="translatedtitle">[IgE-induced anaphylactic reaction after eating <span class="hlt">lamb</span> meat].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johansen, Kasper Lorenz; Rasmussen, Kirsten</p> <p>2014-08-25</p> <p>This article presents the case of a 54-year-old male, who was admitted to hospital after suffering a severe anaphylactic reaction after tasting a spoonful of chili con carne and four months later after eating <span class="hlt">lamb</span> meat. Galactose-alpha-1,3-galactose allergy was suspected and the subsequent blood test showed highly elevated specific IgE levels. Delayed allergy to meat is a relatively new type of allergy and the delayed onset of allergic symptoms poses a diagnostic challenge to the physician. This type of allergy should be considered when there has been no obvious allergen exposition prior to the allergic reaction. PMID:25293709</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..93q4306Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..93q4306Z"><span id="translatedtitle">Focusing of the lowest-order antisymmetric <span class="hlt">Lamb</span> mode behind a gradient-index acoustic metalens with local resonators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Jinfeng; Bonello, Bernard; Boyko, Olga</p> <p>2016-05-01</p> <p>We have investigated the focusing of the lowest-order antisymmetric <span class="hlt">Lamb</span> mode (A0) behind a positive gradient-index (GRIN) acoustic metalens consisting of air holes drilled in a silicon plate with silicon pillars erected on one face of the lens. We have analyzed the focusing in the near field as the result of the coupling between the flexural resonant mode of the pillars and the vibration mode of the air/silicon phononic crystal. We highlight the role played by the polarization coherence between the resonant mode and the vibration of the plate. We demonstrate both numerically and experimentally the focusing behind the lens over a spot less than half a wavelength, paving a way for performance of acoustic lenses beyond the diffraction limit. Our findings can be easily extended to other types of elastic <span class="hlt">wave</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24815248','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24815248"><span id="translatedtitle">The interaction of Rayleigh <span class="hlt">waves</span> with delaminations in composite laminates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chakrapani, Sunil Kishore; Dayal, Vinay</p> <p>2014-05-01</p> <p>In the present work, the interaction of Rayleigh <span class="hlt">waves</span> with a delamination in a fiber reinforced composite plate was analyzed. Rayleigh <span class="hlt">waves</span>, upon interacting with delamination mode, convert into <span class="hlt">Lamb</span> <span class="hlt">waves</span> in the delamination zone. These guided <span class="hlt">Lamb</span> modes have the capability to mode convert back into Rayleigh modes when they interact with the edge of the delamination. A unidirectional glass/epoxy laminate with a delamination of known size was fabricated and tested using air-coupled ultrasonics. Finite element models were developed to understand the mode conversions occurring at various sections of the delamination. Particle displacements along with numerical and experimental velocities were considered to identify each mode. Conclusions were drawn based on the velocity analysis. PMID:24815248</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18676732','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18676732"><span id="translatedtitle">Carcass composition and meat quality of equally mature kids and <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Santos, V A C; Silva, S R; Azevedo, J M T</p> <p>2008-08-01</p> <p>Carcass composition and meat quality attributes of 55 suckling kids (27 males and 28 females) and 57 suckling <span class="hlt">lambs</span> (28 males and 29 females) of Portuguese native breeds were investigated. These suckling kid and <span class="hlt">lamb</span> meats are European meat quality labels produced according to "Cabrito de Barroso- PGI" and "Borrego Terrincho-PDO" specifications, respectively. Female kids were slaughtered at 9.1 +/- 0.36 kg of BW, and male kids were slaughtered at 10.4 +/- 0.37 kg of BW, corresponding to 20.1 and 17.7% of maturity, respectively. Female <span class="hlt">lambs</span> were slaughtered at 8.6 +/- 0.53 kg of BW, and male <span class="hlt">lambs</span> were slaughtered at 9.9 +/- 0.23 kg of BW, corresponding to 19.9 and 17.1% of maturity, respectively. At 24 h postmortem, various yield and quality measurements were collected. The left sides of the carcasses were dissected into muscle, subcutaneous fat, intermuscular fat, and bone. Final pH, instrumental color (L*, a*, b*), carcass measurements, and kidney knob and pelvic fat were also determined. Samples of LM were taken from the lumbar and thoracic cuts for intramuscular and meat quality determinations. At 72 h postmortem, a sample of LM was used for cooking losses and Warner-Bratzler shear force determination. Suckling <span class="hlt">lambs</span> had greater dressing proportion than suckling kids (P < 0.01). Carcass fatness was not affected by species (P > 0.05), but females had greater kidney knob and pelvic fat proportion than males (P < 0.01). <span class="hlt">Lambs</span> had greater proportions of the highly valued leg cut and lower proportions of shoulder, anterior rib, and neck cuts than kids. Dissection results indicated that kid carcasses had greater muscle content and lower dissected fat and bone than <span class="hlt">lambs</span>. Kids had greater (P < 0.001) muscle ultimate pH value than <span class="hlt">lambs</span> (5.8 +/- 0.02 vs. 5.6 +/- 0.02). Males had greater (P < 0.05) muscle ultimate pH value than females (5.7 +/- 0.02 vs. 5.6 +/- 0.02). The kid meat was significantly lighter (P < 0.05) and less yellow (P < 0.001) than the <span class="hlt">lamb</span> meat. Kids</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JCoPh.258..381H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JCoPh.258..381H"><span id="translatedtitle">Numerical modeling of <span class="hlt">wave</span> propagation in functionally graded materials using time-domain spectral Chebyshev elements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hedayatrasa, Saeid; Bui, Tinh Quoc; Zhang, Chuanzeng; Lim, Chee Wah</p> <p>2014-02-01</p> <p>Numerical modeling of the <span class="hlt">Lamb</span> <span class="hlt">wave</span> propagation in functionally graded materials (FGMs) by a two-dimensional time-domain spectral finite element method (SpFEM) is presented. The high-order Chebyshev polynomials as approximation functions are used in the present formulation, which provides the capability to take into account the through thickness variation of the material properties. The efficiency and accuracy of the present model with one and two layers of 5th order spectral elements in modeling <span class="hlt">wave</span> propagation in FGM plates are analyzed. Different excitation frequencies in a wide range of 28-350 kHz are investigated, and the dispersion properties obtained by the present model are verified by reference results. The through thickness <span class="hlt">wave</span> structure of two principal <span class="hlt">Lamb</span> modes are extracted and analyzed by the symmetry and relative amplitude of the vertical and horizontal oscillations. The differences with respect to <span class="hlt">Lamb</span> modes generated in homogeneous plates are explained. Zero-crossing and wavelet signal processing-spectrum decomposition procedures are implemented to obtain phase and group velocities and their dispersion properties. So it is attested how this approach can be practically employed for simulation, calibration and optimization of <span class="hlt">Lamb</span> <span class="hlt">wave</span> based nondestructive evaluation techniques for the FGMs. The capability of modeling stress <span class="hlt">wave</span> propagation through the thickness of an FGM specimen subjected to impact load is also investigated, which shows that the present method is highly accurate as compared with other existing reference data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020009163&hterms=sundaresan&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsundaresan','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020009163&hterms=sundaresan&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsundaresan"><span id="translatedtitle">Active <span class="hlt">Wave</span> Propagation and Sensing in Plates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ghoshal, Anindya; Martin, William N.; Sundaresan, Mannur J.; Schulz, Mark J.; Ferguson, Frederick</p> <p>2001-01-01</p> <p>Health monitoring of aerospace structures can be done using an active interrogation approach with diagnostic <span class="hlt">Lamb</span> <span class="hlt">waves</span>. Piezoelectric patches are often used to generate the <span class="hlt">waves</span>, and it is helpful to understand how these <span class="hlt">waves</span> propagate through a structure. To give a basic understanding of the actual physical process of <span class="hlt">wave</span> propagation, a model is developed to simulate asymmetric <span class="hlt">wave</span> propagation in a panel and to produce a movie of the <span class="hlt">wave</span> motion. The <span class="hlt">waves</span> can be generated using piezoceramic patches of any size or shape. The propagation, reflection, and interference of the <span class="hlt">waves</span> are represented in the model. Measuring the <span class="hlt">wave</span> propagation is the second important aspect of damage detection. Continuous sensors are useful for measuring <span class="hlt">waves</span> because of the distributed nature of the sensor and the <span class="hlt">wave</span>. Two sensor designs are modeled, and their effectiveness in measuring acoustic <span class="hlt">waves</span> is studied. The simulation model developed is useful to understand <span class="hlt">wave</span> propagation and to optimize the type of sensors that might be used for health monitoring of plate-like structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/3164715','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/3164715"><span id="translatedtitle">Prostaglandin E2 causes hypoventilation and apnea in newborn <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guerra, F A; Savich, R D; Wallen, L D; Lee, C H; Clyman, R I; Mauray, F E; Kitterman, J A</p> <p>1988-05-01</p> <p>To test the hypothesis that prostaglandin (PG) E2 is a respiratory depressant in the newborn <span class="hlt">lamb</span>, 12 chronically catheterized, unanesthetized <span class="hlt">lambs</span> (age 2-6 days) were infused with progressively increasing doses of PGE2 (0.1, 0.5, 1.0, and 5.0 micrograms.kg-1.min-1; 30 min for each dose) into the ascending aorta. PGE2 caused significant progressive decreases in ventilation (due to decreased tidal volume and breathing rate), heart rate, blood pressure, and percent of the time spent in low-voltage electrocortical activity (LVA). PGE2 also caused respiratory acidosis, hypoxemia, and increased frequency and duration of apneic events (greater than 3 s). During the infusion there was a dose-related increase in plasma concentration of PGE2. At 30 min postinfusion, all measured variables showed recovery, although arterial pH, CO2 tension, and plasma PGE2 remained significantly different from control values, and the percent time in LVA was even higher than during control. Infusion of the vehicle alone (n = 5) caused no significant changes in any of the measured variables. The results, taken in combination with previous fetal studies, indicate that PGE2 has marked inhibitory effects on breathing movements both before and after birth. PMID:3164715</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23958762','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23958762"><span id="translatedtitle"><span class="hlt">LAMB</span>3 mutations causing autosomal-dominant amelogenesis imperfecta.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, J W; Seymen, F; Lee, K E; Ko, J; Yildirim, M; Tuna, E B; Gencay, K; Shin, T J; Kyun, H K; Simmer, J P; Hu, J C-C</p> <p>2013-10-01</p> <p>Amelogenesis imperfecta (AI) can be either isolated or part of a larger syndrome. Junctional epidermolysis bullosa (JEB) is a collection of autosomal-recessive disorders featuring AI associated with skin fragility and other symptoms. JEB is a recessive syndrome usually caused by mutations in both alleles of COL17A1, LAMA3, <span class="hlt">LAMB</span>3, or LAMC2. In rare cases, heterozygous carriers in JEB kindreds display enamel malformations in the absence of skin fragility (isolated AI). We recruited two kindreds with autosomal-dominant amelogenesis imperfecta (ADAI) characterized by generalized severe enamel hypoplasia with deep linear grooves and pits. Whole-exome sequencing of both probands identified novel heterozygous mutations in the last exon of <span class="hlt">LAMB</span>3 that likely truncated the protein. The mutations perfectly segregated with the enamel defects in both families. In Family 1, an 8-bp deletion (c.3446_3453del GACTGGAG) shifted the reading frame (p.Gly 1149Glufs*8). In Family 2, a single nucleotide substitution (c.C3431A) generated an in-frame translation termination codon (p.Ser1144*). We conclude that enamel formation is particularly sensitive to defects in hemidesmosome/basement-membrane complexes and that syndromic and non-syndromic forms of AI can be etiologically related. PMID:23958762</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24729076','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24729076"><span id="translatedtitle">Relative bioavailability of soil-bound chlordecone in growing <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jurjanz, S; Jondreville, C; Mahieu, M; Fournier, A; Archimède, H; Rychen, G; Feidt, C</p> <p>2014-10-01</p> <p>The pollution of soil with the pesticide chlordecone (CLD) is a problem for the use of agricultural surfaces even years after its use has been forbidden. Therefore, the exposure of free-ranged animals such as ruminants needs to be investigated in order to assess the risk of contamination of the food chain. Indeed, measured concentrations could be integrated in a lowered extent if the soil binding would reduce the bioavailability of the pesticide. This bioavailability of soil-bound CLD in a heavily polluted andosol has been investigated relatively of CLD given via spiked oil. Twenty-four weaned <span class="hlt">lambs</span> were exposed to graded doses of 2, 4 or 6 μg CLD/kg body weight during 15 days via the contaminated soil in comparison to spiked oil. The concentration of this pesticide has been determined in two target tissues: blood serum and kidney fat. The relative bioavailability (RBA) corresponds to the slope ratio between the test matrix-contaminated soil- in comparison to the reference matrix oil. The RBA of the soil-bound CLD was not found to significantly differ from the reference matrix oil in <span class="hlt">lambs</span> meaning that the pesticide ingested by grazing ruminants would not be sequestered by soil binding. Therefore, CLD from soil gets bioavailable within the intestinal level and exposure to contaminated soil has to be integrated in risk assessments. PMID:24729076</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27288901','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27288901"><span id="translatedtitle">Meat quality of <span class="hlt">lambs</span> fed diets with peanut cake.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bezerra, L S; Barbosa, A M; Carvalho, G G P; Simionato, J I; Freitas, J E; Araújo, M L G M L; Pereira, L; Silva, R R; Lacerda, E C Q; Carvalho, B M A</p> <p>2016-11-01</p> <p>Replacement of soybean meal by peanut cake was evaluated on the meat quality of 45 Dorper × Santa Inês crossbred <span class="hlt">lambs</span>. Animals were distributed in a completely randomized design, with five treatments and nine repetitions, and fed Tifton-85 hay and a concentrate mixed with 0.0%, 25.0%, 50.0%, 75.0% or 100.0% peanut cake based on the dry mass of the complete diet. The longissimus lumborum muscle was used to determine the proximate composition, physical-chemical characteristics and fatty acid profile. Significant differences (P<0.05) were found for the crude protein and ether extract levels, with average values of 23.38% and 2.15% in the sheep meat, respectively. The physical-chemical characteristics of the loin were not affected (P>0.05) by the diets. The fatty acid profile was affected by peanut cake supplementation for myristic, myristoleic, palmitoleic, linolenic and arachidonic fatty acids. Peanut cake can be added in the diet of <span class="hlt">lambs</span> no effect on physical-chemical characteristics. However, the total replacement of the soybean meal altered the proximate composition and fatty acid profile of the meat. PMID:27288901</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6270976','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6270976"><span id="translatedtitle">Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jobe, A.H.; Ikegami, M.; Seidner, S.R.; Pettenazzo, A.; Ruffini, L.</p> <p>1989-02-01</p> <p>Preterm <span class="hlt">lambs</span> were delivered at 138 days gestational age and ventilated for periods up to 24 h in order to study surfactant metabolism and surfactant function. The surfactant-saturated phosphatidylcholine pool in the alveolar wash was 13 +/- 4 mumol/kg and did not change from 10 min to 24 h after birth. Trace amounts of labeled natural sheep surfactant were mixed with fetal lung fluid at birth. By 24 h, 80% of the label had become lung-tissue-associated, yet there was no loss of label from phosphatidylcholine in the lungs when calculated as the sum of the lung tissue plus alveolar wash. De novo synthesized phosphatidylcholine was labeled with choline given by intravascular injection at 1 h of age. Labeled phosphatidylcholine accumulated in the lung tissue linearly to 24 h, and the labeled phosphatidylcholine moved through lamellar body to alveolar pools. The turnover time for alveolar phosphatidylcholine was estimated to be about 13 h, indicating an active metabolic pool. A less surface-active surfactant fraction recovered as a supernatant after centrifugation of the alveolar washes at 40,000 x g increased from birth to 10 min of ventilation, but no subsequent changes in the distribution of surfactant phosphatidylcholine in surfactant fractions occurred. The results were consistent with recycling pathway(s) that maintained surface-active surfactant pools in preterm ventilated <span class="hlt">lambs</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/9303449','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/9303449"><span id="translatedtitle">Vaccination schedules to raise antibody concentrations against epsilon-toxin of Clostridium perfringens in ewes and their triplet <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de la Rosa, C; Hogue, D E; Thonney, M L</p> <p>1997-09-01</p> <p>The objective of this experiment was to compare vaccination schedules for ewes and their <span class="hlt">lambs</span> to raise antibody concentrations to epsilon-toxin of Clostridium perfringens, the causative agent of enterotoxemia. Half of 200 Finnsheep x Dorset ewes were vaccinated with C. perfringens type D toxoid vaccine 3 wk before <span class="hlt">lambing</span>. Serum samples were obtained from 20 ewes that were to be vaccinated and 20 ewes that would remain unvaccinated before treatment and at wk 2, 1, and 0 before the start of <span class="hlt">lambing</span>. Antibody concentrations in sera of unvaccinated ewes remained at 2 IU/mL, but they peaked in vaccinated ewes at 15 IU/mL by wk 1 before <span class="hlt">lambing</span>. <span class="hlt">Lambs</span> from each of the first 13 and the first 14 sets of triplets from vaccinated and unvaccinated ewes, respectively, received one of three vaccination treatments: no vaccine (control), vaccination on d 1 and 21 of age, or vaccination on d 21 and 42 of age. Antibody concentrations declined in sera of vaccinated ewes from 8.5 IU/mL immediately after <span class="hlt">lambing</span> to 3 IU/mL 12 wk later. Vaccination of <span class="hlt">lambs</span> did not increase sera antibody concentration. However, prepartum vaccination of ewes significantly increased <span class="hlt">lamb</span> antibody concentrations (19 IU/mL) compared with <span class="hlt">lambs</span> reared by unvaccinated ewes (2 IU/mL). Vaccination of ewes resulted in <span class="hlt">lambs</span> with higher antibody concentrations until wk 10 postpartum. Concentrations declined to .6 IU/mL in all <span class="hlt">lambs</span> at 12 wk. Because concentrations of .2 IU/mL may be protective, these results indicate that vaccination of ewes before <span class="hlt">lambing</span> imparts passive protection in <span class="hlt">lambs</span> to 12 wk of age, whereas vaccination of young <span class="hlt">lambs</span> provides no added protection. PMID:9303449</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23286994','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23286994"><span id="translatedtitle">Sericea lespdeza as an aid in the control of Emeria spp. in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burke, J M; Miller, J E; Terrill, T H; Orlik, S T; Acharya, M; Garza, J J; Mosjidis, J A</p> <p>2013-03-31</p> <p>The objective was to examine the effects of feeding sericea lespedeza leaf meal (SL) on control of coccidiosis in <span class="hlt">lambs</span>. In Exp. 1, naturally infected <span class="hlt">lambs</span> (n=76) were weaned (102.7±1.4 d of age) in May (spring) and randomly assigned in a 2×2 factorial design to receive 2% of BW/d of alfalfa pellets (control) or SL with or without amprolium added to drinking water (n=38/level or 19/treatment). Fecal oocyst counts (FOC), egg counts (FEC), and fecal score (1=solid pellets; 5=slurry) were determined every 7d between weaning and 21 d post-weaning. In Exp. 2, twin rearing ewes were randomly assigned to two groups, and their naturally infected <span class="hlt">lambs</span> were fed a control creep supplement (16% CP; n=40) or SL pellets (14% CP; n=32) 30 d before weaning. Intake of SL was initially low (100g/<span class="hlt">lamb</span> daily) and increased to 454 g/<span class="hlt">lamb</span> daily after weaning. <span class="hlt">Lambs</span> were weaned at 103.6±0.9 d of age and moved to semi-confinement. The FEC, FOC, packed cell volume (PCV), fecal score, and dag score (soiling around rear of <span class="hlt">lamb</span>; 1=no soiling; 5=heavy soiling) were determined at d -14, 0 (weaning), 7, 14, and 21. In Exp. 3, <span class="hlt">lambs</span> were randomly assigned to a control or SL diet (n=12/diet) fed at 1.4 kg/d for 22d and inoculated with 50,000 sporulated oocysts on d 8, 11, and 13. The FEC, FOC, and fecal score were determined every 2 to 3d between d 1 and 29 (d 0=first day of dietary treatment). Data on all experiments were analyzed using mixed models. The FOC and FEC data were log transformed. Chi squared analysis was used to determine differences in incidence of treatment (sulfadimethoxine) for coccidiosis in Exp. 1 and 2. In Exp. 1, FOC and FEC were similar between dietary groups, and FOC declined more rapidly in amprolium treated <span class="hlt">lambs</span> following weaning (P<0.001). Fecal score was higher in the control compared with the SL fed <span class="hlt">lambs</span> (P=0.05), suggesting more signs of coccidiosis in control <span class="hlt">lambs</span>. In Exp. 2, FOC was similar initially but was reduced in SL fed <span class="hlt">lambs</span> by weaning and remained</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26915456','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26915456"><span id="translatedtitle">Effect of pre-slaughter handling, exercise and the presence of a dog on <span class="hlt">lamb</span> welfare and meat quality.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sutherland, M A; Worth, G M; Stuart, A D; Dobbie, P M; Clerens, S</p> <p>2016-08-01</p> <p>Before slaughter, <span class="hlt">lambs</span> may experience several stressors such as feed and water deprivation, handling and transport that have the potential to negatively impact welfare and meat quality. The objective of this study was to evaluate the effect of pre-slaughter handling, exercise and the presence of a dog on the behaviour and physiology of <span class="hlt">lambs</span> and meat quality at slaughter. At 6 months of age, 60 <span class="hlt">lambs</span> (n=20 <span class="hlt">lambs</span>/replicate; three replicates) were allocated to one of the two treatment groups (n=30 <span class="hlt">lambs</span>/treatment): low (LOW) intensive handling or high (HIGH) intensive handling. LOW <span class="hlt">lambs</span> were moved short distances, quietly and without the use of a dog before transport. HIGH <span class="hlt">lambs</span> were moved quickly, long distances and with a dog present before transport. <span class="hlt">Lamb</span> behaviour (standing, lying, rumination and panting) was recorded for 1 h before (post-treatment) and after transport (post-transport), and for 30 min before slaughter (pre-slaughter). Blood samples were collected before (baseline), after transport (post-transport) and at exsanguination (at slaughter) to assess cortisol, lactate and non-esterified fatty acid (NEFA) concentrations. At slaughter, <span class="hlt">lamb</span> carcases (M. longissimus lumborum) were evaluated for pH levels, drip and cook loss, and tenderness. HIGH <span class="hlt">lambs</span> spent more time standing (P<0.001) and panting (P<0.001) and less time lying (P<0.001) and ruminating (P<0.001) post-treatment than LOW <span class="hlt">lambs</span>, but more (P<0.001) time ruminating post-transport. All <span class="hlt">lambs</span> spent more time standing (P<0.001) and less time lying (P<0.001) and panting (P<0.001) post-transport and pre-slaughter than post-treatment. Cortisol concentrations were greater (P<0.001) in <span class="hlt">lambs</span> post-transport and at slaughter compared with baseline values. Lactate concentrations were lower (P=0.002) in HIGH than LOW <span class="hlt">lambs</span>. In addition, NEFA concentrations were higher (P<0.001) post-transport and at slaughter in HIGH compared with LOW <span class="hlt">lambs</span>. Ultimate pH was higher (P<0.001) in HIGH than LOW <span class="hlt">lambs</span> and p</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26974594','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26974594"><span id="translatedtitle">The impact of genetics on retail meat value in Australian <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anderson, F; Pethick, D W; Gardner, G E</p> <p>2016-07-01</p> <p>Lean (muscle), fat, and bone composition of 1554 <span class="hlt">lamb</span> carcasses from Maternal, Merino and Terminal sired <span class="hlt">lambs</span> was measured using computed tomography scanning. <span class="hlt">Lamb</span> sires were diverse in their range of Australian Sheep Breeding Values for post weaning c-site eye muscle depth (PEMD) and fat depth (PFAT), and post weaning weight (PWWT). Lean value, representing predicted lean weight multiplied by retail value, was determined for <span class="hlt">lambs</span> at the same carcass weight or the same age. At the same carcass weight, lean value was increased the most by reducing sire PFAT, followed by increasing PEMD and PWWT. However for <span class="hlt">lambs</span> of the same age, increasing sire PWWT increased lean value the most. Terminal sired <span class="hlt">lambs</span>, on average, had greater lean value irrespective of whether comparisons were made at the same age or weight. Lean value was greater in Merino compared to Maternal sired <span class="hlt">lambs</span> at equal carcass weight, however the reverse was true when comparisons were made at the same age. PMID:26974594</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20374881','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20374881"><span id="translatedtitle">Factors associated with the purchase of designation of origin <span class="hlt">lamb</span> meat.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sepúlveda, Wilmer S; Maza, María T; Mantecón, Angel R</p> <p>2010-05-01</p> <p>As in other products, quality labels that designate the origin of <span class="hlt">lamb</span> meat are increasingly used by consumers as a cue for inferring the quality of the meat. The aim of the present paper is to identify those factors that most affect the purchase of <span class="hlt">lamb</span> with an origin quality label. For this purpose a total of 371 questionnaires were carried out in the region of Aragón located in the north east of Spain. This region produces 48.5% of the total amount of <span class="hlt">lamb</span> meat with a Spanish protected geographical indication, whilst it also has the country's greatest per capita consumption (6.8 kg/person/year). To identify the most determining factors a logistic regression analysis was performed between three groups of buyers, characterised by their degree of loyalty towards purchasing origin quality-labelled <span class="hlt">lamb</span>. The results show that those buyers who are less loyal to the label pay less attention to the origin of the meat when forming quality expectations at the time of purchase, whilst these are the buyers that place greatest importance on animal feeding as an aspect affecting the final quality of <span class="hlt">lamb</span> meat. The buyers that are very loyal to the quality label associate this label with a product that offers greater guarantees and is healthier. <span class="hlt">Lamb</span> meat buyers with medium loyalty to quality labels, consider quality-labelled <span class="hlt">lamb</span> meat has better intrinsic attributes. PMID:20374881</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21240654','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21240654"><span id="translatedtitle">Effects of road type during transport on <span class="hlt">lamb</span> welfare and meat quality in dry hot climates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miranda-de la Lama, Genaro C; Monge, Paula; Villarroel, Morris; Olleta, Jose Luis; García-Belenguer, Sylvia; María, Gustavo A</p> <p>2011-06-01</p> <p>This study determined whether transporting <span class="hlt">lambs</span> on paved (PR) or unpaved roads (UR) for 3 h had an effect on plasma stress indicators (cortisol, lactate, glucose, creatine kinase [CK], red blood cells, white blood cells, hematocrit, and neutrophil/lymphocyte [N/L] ratio) and instrumental meat quality (pH24, bruising score, water holding capacity [WHC], color, and texture). A total of 48 Rasa Aragonesa male <span class="hlt">lambs</span> were used that were approximately 100 days old (12.5 kg ± 1.64, carcass weight). The results suggest that transport on unpaved roads had a significant influence on physiological and hematological stress parameters. Road type had a significant effect on all variables, except for white and red blood cells, and hematocrit levels. The UR <span class="hlt">lambs</span> had significantly higher (at least p ≤ 0.01) cortisol, lactate, glucose, and CK levels and a higher N/L ratio than PR <span class="hlt">lambs</span>. Meat from UR <span class="hlt">lambs</span> had some dark-cutting characteristics, with a darker color, higher ultimate pH, and higher tenderness values than PR. In conclusion, <span class="hlt">lambs</span> transported on unpaved roads had a more intense stress response and poorer meat quality than <span class="hlt">lambs</span> transported on paved roads. An effort to improve the logistics associated with route planning is necessary to prevent welfare problems during transport to slaughter. PMID:21240654</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=443232','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=443232"><span id="translatedtitle">Blood volume and body fluid compartments in <span class="hlt">lambs</span> with aortopulmonary left-to-right shunts.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gratama, J W; Dalinghaus, M; Meuzelaar, J J; Gerding, A M; Koers, J H; Zijlstra, W G; Kuipers, J R</p> <p>1992-01-01</p> <p>A left-to-right shunt is accompanied by an increased plasma and blood volume. Since this is likely realized through renin/aldosterone-mediated salt and water retention, other body fluid compartments may be changed too. Therefore, we studied blood volume and body fluid compartments by a single-injection, triple-indicator dilution technique in nine 8-wk-old <span class="hlt">lambs</span> with an aortopulmonary left-to-right shunt (55 +/- 3% of left ventricular output; mean +/- SEM) and in 11 control <span class="hlt">lambs</span>, 2.5 wk after surgery. Systemic blood flow was maintained at the same level as in control <span class="hlt">lambs</span>, but the aortic pressure of the shunt <span class="hlt">lambs</span> was lower. Blood volume in shunt <span class="hlt">lambs</span> was larger than in control <span class="hlt">lambs</span> (110 +/- 6 vs. 84 +/- 7 ml/kg, P < 0.001) through an increase in plasma volume, which correlated significantly with the magnitude of the left-to-right shunt (r = 0.81, P < 0.01). Red blood cell volume was equal to that of control <span class="hlt">lambs</span>. Evidence was obtained that the increase in plasma volume was induced by a transient increase in renin (8.0 +/- 2.2 vs. 1.6 +/- 0.2 nmol.l-1.h-1; P < 0.02) and aldosterone (0.51 +/- 0.14 vs. 0.24 +/- 0.09 nmol/liter) concentrations. Interstitial water volume, however, was not significantly different from that in control <span class="hlt">lambs</span>. The amount of intravascular protein was significantly higher than in control <span class="hlt">lambs</span> (5.0 +/- 0.3 vs. 3.5 +/- 0.2 g/kg body mass, P < 0.001). There were no significant differences in intracellular and total body water volumes between the two groups. We conclude that the increased amount of intravascular protein confines the fluid retained by the kidneys to the vascular compartment. PMID:1430202</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/14578364','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/14578364"><span id="translatedtitle">Regulation of brain water during acute glucose-induced hyperosmolality in ovine fetuses, <span class="hlt">lambs</span>, and adults.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stonestreet, Barbara S; Petersson, Katherine H; Sadowska, Grazyna B; Patlak, Clifford S</p> <p>2004-02-01</p> <p>We tested the hypothesis that, during acute glucose-induced hyperosmolality, the brain shrinks less than predicted on the basis of an ideal osmometer and that brain volume regulation is present in fetuses, premature and newborn <span class="hlt">lambs</span>. Brain water responses to glucose-induced hyperosmolality were measured in the cerebral cortex, cerebellum, and medulla of fetuses at 60% of gestation, premature ventilated <span class="hlt">lambs</span> at 90% of gestation, newborn <span class="hlt">lambs</span>, and adult sheep. After exposure of the sheep to increases in osmolality with glucose plus NaCl, brain water and electrolytes were measured. The ideal osmometer is a system in which impermeable solutes do not enter or leave in response to an osmotic stress. In the absence of volume regulation, brain solute remains constant as osmolality changes. The osmotically active solute demonstrated direct linear correlations with plasma osmolality in the cerebral cortex of the fetuses at 60% of gestation (r = 0.72, n = 24, P = 0.0001), premature <span class="hlt">lambs</span> (r = 0.58, n = 22, P = 0.005), newborn <span class="hlt">lambs</span> (r = 0.57, n = 24, P = 0.004), and adult sheep (r = 0.70, n = 18, P = 0.001). Similar findings were observed in the cerebellum and medulla. Increases in the quantity of osmotically active solute over the range of plasma osmolalities indicate that volume regulation was present in the brain regions of the fetuses, premature <span class="hlt">lambs</span>, newborn <span class="hlt">lambs</span>, and adult sheep during glucose-induced hyperosmolality. We conclude that, during glucose-induced hyperosmolality, the brain shrinks less than predicted on the basis of an ideal osmometer and exhibits volume regulation in fetuses at 60% of gestation, premature <span class="hlt">lambs</span>, newborn <span class="hlt">lambs</span>, and adult sheep. PMID:14578364</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25846838','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25846838"><span id="translatedtitle">Reproductive and sexual behaviour development of dam or artificially reared male <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Damián, Juan Pablo; Beracochea, Florencia; Hötzel, Maria José; Banchero, Georgget; Ungerfeld, Rodolfo</p> <p>2015-08-01</p> <p>The objective of this study was to determine if artificially reared male <span class="hlt">lambs</span> differ from those reared by their mothers in their reproductive development and sexual behaviour during the first breeding season and in their serum testosterone to a GnRH challenge at the end of the first breeding season. <span class="hlt">Lambs</span> were assigned to two experimental groups: 1) artificially reared <span class="hlt">lambs</span>, separated from their dams 24-36h after birth (Week 0) and fed sheep milk until 10weeks of age (group AR, n=14); and 2) <span class="hlt">lambs</span> reared by their dams until 10weeks of age (group DR, n=13). Reproductive parameters and sexual behaviour were recorded from Weeks 9 to 39. The GnRH challenge was performed on Week 40. Body weight, scrotal circumference, gonado-somatic index, testosterone concentration and sperm parameters were unaffected by group, but increased with age (P<0.0001). <span class="hlt">Lambs</span> reared by their mothers had greater values of gonado-somatic index on Weeks 9, 16 and 19 (P<0.05), and tended to reach puberty earlier than AR (22.9±0.7 vs. 25.1±1.1weeks, respectively, P=0.087). <span class="hlt">Lambs</span> reared by their mothers presented more lateral approaches and mount attempts than AR (P<0.05), and DR <span class="hlt">lambs</span> presented more mounts on Weeks 32 and 39 than AR (P<0.05). Blood testosterone concentrations 3.5 and 4h after the GnRH challenge were higher in AR than in DR <span class="hlt">lambs</span> (P<0.05). In conclusion mother rearing promoted sexual behaviour and reproductive performance of male <span class="hlt">lambs</span>. PMID:25846838</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25048992','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25048992"><span id="translatedtitle">Embryo development, fetal growth and postnatal phenotype of eGFP <span class="hlt">lambs</span> generated by lentiviral transgenesis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Crispo, M; Vilariño, M; dos Santos-Neto, P C; Núñez-Olivera, R; Cuadro, F; Barrera, N; Mulet, A P; Nguyen, T H; Anegón, I; Menchaca, A</p> <p>2015-02-01</p> <p>Lentiviral technology has been recently proposed to generate transgenic farm animals more efficiently and easier than traditional techniques. The objective was to evaluate several parameters of <span class="hlt">lambs</span> obtained by lentiviral transgenesis in comparison with non-transgenic counterparts. In vitro produced embryos were microinjected (TG group) at two-cell stage with a lentiviral construct containing enhanced green fluorescent protein (eGFP) gene, while embryos produced by in vitro fertilization (IVF group) or intrauterine insemination (IUI group) were not microinjected. Microinjection technique efficiently generated eight-cell transgenic embryos (97.4%; 114/117). Development rate on day 5 after fertilization was similar for TG (39.3%, 46/117) and IVF embryos (39.6%, 44/111). Pregnancy rate was detected in 50.0% (6/12) of recipient ewes with TG embryos, in 46.7% (7/15) with IVF embryos, and in 65.0% (13/20) of IUI ewes (P = NS). Nine <span class="hlt">lambs</span> were born in TG group, six <span class="hlt">lambs</span> in IVF group, and 16 <span class="hlt">lambs</span> in IUI group. All TG <span class="hlt">lambs</span> (9/9) were GFP positive to real-time PCR and eight (88.9%) showed a strong and evident GFP expression in mucosae, eyes and keratin tissues. Fetal growth monitored every 15 day by ultrasonography did not show significant differences. Transgenic <span class="hlt">lambs</span> neither differ in morphometric variables in comparison with non transgenic IVF <span class="hlt">lambs</span> within 3 months after birth. Transmission of the transgene to the progeny was observed in green fluorescent embryos produced by IVF using semen from the TG founder <span class="hlt">lambs</span>. In conclusion, this study demonstrates the high efficiency of lentiviral technology to produce transgenic sheep, with no clinic differences in comparison with non transgenic <span class="hlt">lambs</span>. PMID:25048992</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26020185','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26020185"><span id="translatedtitle">The effect of cyclical and severe heat stress on growth performance and metabolism in Afshari <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mahjoubi, E; Yazdi, M Hossein; Aghaziarati, N; Noori, G R; Afsarian, O; Baumgard, L H</p> <p>2015-04-01</p> <p>The extent to which reduced feed intake contributes to decreased growth during heat stress (HS) in the ovine model is not clear. To evaluate the impact of decreased DMI on performance, we conducted an experiment on growing <span class="hlt">lambs</span> experiencing a cyclical but extensive heat load. Sixteen intact male Afshari <span class="hlt">lambs</span> (40.1 ± 1.9 kg) were used in a completely randomized design in 2 periods. In period 1, all 16 <span class="hlt">lambs</span> were housed in thermal neutral (TN) conditions (22.2 ± 3.1°C and a temperature-humidity index [THI] of 67.9 ± 3.2) and fed at libitum for 8 d. In period 2 (P2), which lasted 9 d, 8 <span class="hlt">lambs</span> were subjected to a cyclical HS condition (33.0 to 45.0°C and a THI of more than 80 at least for 24 h/d and more than 90 for 8 h/d). The other 8 <span class="hlt">lambs</span> were maintained in TN conditions but pair-fed (pair-fed thermal neutral [PFTN]) to the HS <span class="hlt">lambs</span>. During each period, DMI and water intake were measured daily. Respiration rate, rectal temperature, and skin temperature at the shoulder, rump, and front and rear leg were recorded at 0700 and 1400 h daily. Dry matte intake declined (17.5%; P < 0.01) in HS <span class="hlt">lambs</span> and, by design, the temporal pattern and magnitude of reduced feed intake was similar in the PFTN controls. Water intake increased (19%; P < 0.05) during P2 in HS but not in the PFTN controls. Heat stress increased the 0700 and 1400 h skin temperature at the shoulder (5 and 9.2%), rump (6.2 and 10.3%), rear (6 and 9.2%), and front leg (6.5 and 9.8%) and respiratory rates (84 and 163% [P < 0.01]at 0700 and 1400 h, respectfully), but only the 1400 h rectal temperature was increased (P < 0.01; 0.65°C) in HS <span class="hlt">lambs</span>. Neither environment nor period affected blood urea nitrogen and glucose concentrations. However, circulating NEFA and insulin were increased and declined (P < 0.01) in PFTN <span class="hlt">lambs</span>, respectively, but neither variable was altered in the HS <span class="hlt">lambs</span>. Growth was reduced in P2 for <span class="hlt">lambs</span> in both treatments, but despite being on a similar reduced plane of nutrition, the HS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4187367','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4187367"><span id="translatedtitle">Isolation of Streptococcus suis from 2 <span class="hlt">lambs</span> with a history of lameness</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Muckle, Anne; López, Alfonso; Gottschalk, Marcelo; López-Méndez, Carlos; Giles, Jan; Lund, Lorraine; Saab, Matthew</p> <p>2014-01-01</p> <p>Streptococcus suis was isolated postmortem from 2 <span class="hlt">lambs</span> with a history of lameness. Identity of S. suis was confirmed by species-specific polymerase chain reaction (PCR) and by 16S rRNA gene sequencing. One isolate was untypable by serotyping and non-encapsulated, while the other isolate was serotype 33. The <span class="hlt">lambs</span> had come from the same farm, and there was no evidence of contact between the <span class="hlt">lambs</span> and pigs. Although the natural niche for S. suis is considered to be the pig, a wide range of host species may be affected by this pathogen. PMID:25320381</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3942938','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3942938"><span id="translatedtitle">Increase in Cardiac Troponin I in a <span class="hlt">Lamb</span> with Tetralogy of Fallot</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>NEUWALD, Elisa Barp; SOARES, Frederico Aécio Carvalho; DREYER, Cristina Terres; CARNESELLA, Samuel; WOUTERS, Angelica Terezinha Barth; GONZÁLEZ, Félix Hilario Diaz; DRIEMEIER, David</p> <p>2013-01-01</p> <p>ABSTRACT This study describes a case of tetralogy of Fallot in a <span class="hlt">lamb</span> showing failure to thrive and signs of respiratory distress. Physical examination, electrocardiography, thoracic radiographies, echocardiography and cardiac troponin I evaluation were performed. The value of cardiac troponin I was compared with the values of 10 healthy <span class="hlt">lambs</span> of the same age and breed, and the affected animal demonstrated an increase in cardiac troponin I. Due to the poor prognosis, euthanasia was indicated, and necropsy confirmed the diagnosis. This is the first report of an increase in cardiac troponin I in a <span class="hlt">lamb</span> with tetralogy of Fallot. PMID:23685750</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5434690','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5434690"><span id="translatedtitle">Cardiovascular and endocrine response to hemorrhage after. cap alpha. /sub 1/-blockade in <span class="hlt">lambs</span> and ewes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Block, S.M.; Rose, J.C.; Ernest, J.M.; Flowe, K.; South, S.; Zimmerman, C.</p> <p>1987-02-01</p> <p>To evaluate the role of the ..cap alpha../sub 1/-adrenergic system in the response to hemorrhage during development, <span class="hlt">lambs</span> and adult sheep were chronically catheterized and hemorrhaged after pretreatment with prazosin or vehicle. The adults became markedly more hypotensive after ..cap alpha../sub 1/-blockade and hemorrhage than after vehicle and hemorrhage, whereas the <span class="hlt">lambs</span> were no more hypotensive when hemorrhaged after prazosin. In the adults and the <span class="hlt">lambs</span> hemorrhage produced elevations in plasma renin activity and arginine vasopressin measured by radioimmunoassay. However, after prazosin, the adults had a far greater increase in arginine vasopressin levels than after vehicle treatment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1175656','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1175656"><span id="translatedtitle">Effect of maternal cold exposure on brown adipose tissue and thermogenesis in the neonatal <span class="hlt">lamb</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Symonds, M E; Bryant, M J; Clarke, L; Darby, C J; Lomax, M A</p> <p>1992-01-01</p> <p>1. This study examines the effect of chronic cold exposure during pregnancy, induced by winter shearing twin-bearing ewes 4 weeks before predicted <span class="hlt">lambing</span> date, on O2 consumption and CO2 production during non-rapid-eye-movement (REM) sleep in <span class="hlt">lambs</span> maintained for at least 1 h at warm (28-18 degrees C) and cold (14-5 degrees C) ambient temperatures at 1, 4, 14 and 30 days of age. This was combined with measurement of the thermogenic activity (GDP binding to uncoupling protein in mitochondrial preparations) of perirenal adipose tissue from <span class="hlt">lambs</span> immediately after birth and at 33 days of age. 2. <span class="hlt">Lambs</span> born from shorn (cold-exposed) ewes were 15% heavier (P < 0.01) and possessed 21% (P < 0.01) more perirenal adipose tissue that contained 40% more protein and mitochondrial protein than unshorn (P < 0.05) controls. Total GDP binding in perirenal adipose tissue was 40% greater (P < 0.05) in <span class="hlt">lambs</span> born from shorn ewes but there was no difference in lipid content of this tissue between the two groups. 3. At 1 day of age, <span class="hlt">lambs</span> born from shorn ewes exhibited a 16% higher (P < 0.05) rate of O2 consumption (per kilogram bodyweight) at the warm temperature and a 40% greater metabolic response to the cold ambient temperature. All <span class="hlt">lambs</span> born from shorn ewes responded to cold exposure without shivering (i.e. via non-shivering thermogenesis) whilst shivering was measured in four out of seven <span class="hlt">lambs</span> in the unshorn group. These differences had disappeared by 4 days of age as a result of a 25% increased (P < 0.01) rate of O2 consumption in the warm in <span class="hlt">lambs</span> born from unshorn ewes and a 20% decrease (P < 0.05) in the response to the cold in <span class="hlt">lambs</span> from shorn ewes. Shivering during cold exposure was measured in six out of nine <span class="hlt">lambs</span> born from shorn ewes indicating a rapid alteration in thermoregulatory responses to cold during the first few days of life. 4. The levels of GDP binding and mitochondrial protein in perirenal adipose tissue fell by one-third in both groups of <span class="hlt">lambs</span> during the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25828655','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25828655"><span id="translatedtitle">Colostrum composition of Santa Inês sheep and passive transfer of immunity to <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alves, A C; Alves, N G; Ascari, I J; Junqueira, F B; Coutinho, A S; Lima, R R; Pérez, J R O; De Paula, S O; Furusho-Garcia, I F; Abreu, L R</p> <p>2015-06-01</p> <p>This study aimed to analyze the chemical composition and the IgG concentration of the colostrum, transitional milk, and mature milk of Santa Inês ewes as well as the transfer of passive immunity to <span class="hlt">lambs</span>. Thirty-two pregnant ewes and 38 <span class="hlt">lambs</span> were used. Ewes were milked immediately after <span class="hlt">lambing</span> and at 12, 24, 36 h and 10 d postpartum. Colostrum was provided to the <span class="hlt">lambs</span> at 40±15 min (mean±SE) after birth and then at 30-min intervals for obtaining the intake closest to 10% of body weight, and transitional milk was provided ad libitum. Blood from the <span class="hlt">lambs</span> was collected 36 h after birth for measuring the serum concentrations of IgG, total protein, albumin, and gamma-globulin. The production was lower in primiparous than in multiparous ewes with body condition score (BCS)<2.75, but did not differ between primiparous and multiparous with BCS≥2.75 (interaction parity and BCS). The IgG concentration and fat, protein, lactose, and defatted dry extract percentages were not affected by the BCS of the ewe at <span class="hlt">lambing</span> or by the parity. The total solids percentage in the colostrum was higher in ewes with BCS<2.75 (interaction BCS and time). The production and the protein, total solid, and defatted dry extract percentages showed quadratic behavior, the fat percentage decreased linearly, and the lactose percentage increased linearly with time postpartum. The IgG concentration in the colostrum was not correlated with the ewe's weight or BCS at the time of <span class="hlt">lambing</span>. Moreover, the parity, the BCS, the ewe's type of gestation, and the <span class="hlt">lamb</span>'s sex did not influence the serum concentrations of IgG, total protein, albumin, and gamma-globulin in <span class="hlt">lambs</span>. Adequate passive immune transfer (PIT) was observed in <span class="hlt">lambs</span> for which the IgG intake was higher than 30 g. Failure in PIT was observed in 39.5% of <span class="hlt">lambs</span> when considering a serum IgG concentration lower than 15 mg/mL and in 21% when considering a serum total protein concentration lower than 45 mg/mL. The mean apparent efficiency of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23738777','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23738777"><span id="translatedtitle">A case of omphalo-ischiopagus (dicephalic dithoracic abdominopagus tetrascelus tetrabrachius) in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Samuel, M O; Wachida, N; Abenga, J H; Kisani, A I; Adamu, S S; Hambesha, P; Gyang, E; Oyedipe, E O</p> <p>2014-08-01</p> <p>This case report describes a rare occurrence of asymmetrical conjoined twinning in <span class="hlt">lambs</span> in Makurdi (Benue state), Middle Belt region of Nigeria. The conjoined twins were delivered normally by a multiparous ewe of about three and a half years old; the female twins had two complete set of limbs. Barium meal and X-ray revealed abnormalities of the skeletal, digestive, urinary and reproductive systems. This condition is rare in sheep and is to the best of our knowledge the first report of omphalo-ishiopagus (dicephalic dithoracic tetrabrachius) twinned <span class="hlt">lambs</span>. The condition always leads to death of the twin <span class="hlt">lambs</span> due to various physical abnormalities. PMID:23738777</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26618955','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26618955"><span id="translatedtitle">Michael E. <span class="hlt">Lamb</span>: Award for Distinguished Senior Career Contributions to Psychology in the Public Interest.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p></p> <p>2015-11-01</p> <p>The APA Awards for Distinguished Contributions to Psychology in the Public Interest recognize persons who have advanced psychology as a science and/or profession by a single extraordinary achievement or a lifetime of outstanding contributions in the public interest. The 2015 co-recipient of the Award for Distinguished Senior Career Contributions to Psychology in the Public Interest is Michael E. <span class="hlt">Lamb</span>. <span class="hlt">Lamb</span> was selected because his "work profoundly shaped the fields of developmental psychology, social welfare, child and family policy, and law." <span class="hlt">Lamb</span>'s award citation, biography, and a selected bibliography are presented here. PMID:26618955</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/14690087','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/14690087"><span id="translatedtitle"><span class="hlt">Lamb</span> and kid mortality in village flocks in the coastal savanna zone of Ghana.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Turkson, P K</p> <p>2003-12-01</p> <p>A cohort study was designed to observe and follow up mortality in <span class="hlt">lambs</span> and kids in 88 flocks of sheep and goats under the traditional production system in five villages within the coastal savanna zone of Ghana over a 2-year period. The overall mortality rates for kids and <span class="hlt">lambs</span> were 30.8% and 33.5%, respectively. Significantly higher proportions of kids (80.2%) and <span class="hlt">lambs</span> (75.6%) up to 3 months of age died compared to kids and <span class="hlt">lambs</span> from 4 to 12 months of age. The differences in mortality rates, either between male and female kids and <span class="hlt">lambs</span> or between single-born and multiple-birth kids and <span class="hlt">lambs</span>, were not significant. The odds ratio (OR) and relative risks (RR) for <span class="hlt">lambs</span> and kids, on the basis of sex and birth types, were not significant; neither were the values obtained for attributable risk, attributable fraction, population attributable risk and population attributable fraction. The overall mortality rate on the basis of species of animal was not significant. At the village level, significant differences in the proportions of mortality on the basis of sex were seen in two villages. At Akotokyir, more male <span class="hlt">lambs</span> (54.2%) died compared to females (27.6%), while at Apewosika more female <span class="hlt">lambs</span> (42.2%) died compared to males (16.7%). The only significant difference in mortality proportions on the basis of birth type at the village level was seen at Apewosika, where more single-born kids died (52.8%) compared to kids born with sibling(s) (28.4%). The significant ORs for mortalities were 3.10 for male <span class="hlt">lambs</span> at Akotokyir, 3.35 for female <span class="hlt">lambs</span> at Apewosika and 2.82 for single-born kids at Apewosika. The corresponding RRs were equally significant. On the basis of species, significantly more <span class="hlt">lambs</span> died at Akotokyir (44.2%) and Kwesimprah (44.7%) compared to kids. The implications of these findings are discussed. PMID:14690087</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24673841','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24673841"><span id="translatedtitle">Maternal influence on feeding site selection of male and female <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wesley, R L; Cibils, A F; Black-Rubio, C M; Pollak, E R; Utsumi, S A</p> <p>2014-06-01</p> <p>We conducted an experiment to determine whether early-life social learning of feeding site selection in <span class="hlt">lambs</span> was sex-specific. Sixteen ewes and their new born <span class="hlt">lambs</span> were used in a controlled experiment. Eight ewe-<span class="hlt">lamb</span> pairs included a male <span class="hlt">lamb</span> and the remaining eight a female <span class="hlt">lamb</span>. All pairs were individually exposed to an experimental arena containing a safe and unsafe artificial feeding site (SFS, UFS) each consisting of nine bowls which contained either ground Bermuda grass hay (SFS) or ground alfalfa hay (UFS). The bowls in UFS were surrounded by bright orange traffic cones (visual cues). Half the ewes were trained with controlled electric shock to avoid UFS. Thus, pairs were randomly assigned to: (1) shock aversion training (SAT) to mothers of male <span class="hlt">lambs</span> (MS); (2) SAT to mothers of female <span class="hlt">lambs</span> (FS); (3) no aversion training (NAT, control) to mothers of male <span class="hlt">lambs</span> (MC); and (4) NAT (control) to mothers of female <span class="hlt">lambs</span> (FC). None of the <span class="hlt">lambs</span> were subjected to SAT. During training, testing, extinction, and retraining ewe-<span class="hlt">lamb</span> pairs were exposed to the arena together. Ewes were then removed from the experiment and two additional extinction phases were conducted with weaned <span class="hlt">lambs</span> alone. Fear conditioning elicited UFS avoidance of both the trained ewes (means±s.e.m. % times observed in UFS during testing phase: FC=95.3±1.70; MC=94.4±4.87; FS=1.6±1.63; MS=0 ±0; P<0.01) and their naïve <span class="hlt">lambs</span> (FC=83.8±6.07%; MC=76.6±6.56%; FS=30.4±7.90%; MS=33.9±9.23%; P<0.01). UFS avoidance in <span class="hlt">lambs</span> occurred regardless of sex and tended to persist after weaning (% times observed in UFS during 1st post-weaning extinction phase: FC=92.6±4.50%; MC=89.8±6.09%; FS=45.1±10.57%; MS=43.5±10.42%; P=0.06). Fear conditioning in mothers appeared to alter sex-related differences in mother-infant behavioral synchrony by increasing and decreasing feeding synchrony of male and female <span class="hlt">lambs</span>, respectively (FC: r=0.52, P<0.01; MC: r=-0.02, P=0.86; FS: r=0.14, P=0.26; MS: r=0.46, P<0</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20675603','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20675603"><span id="translatedtitle">Enhancement technology improves palatability of normal and callipyge <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Everts, A K R; Wulf, D M; Wheeler, T L; Everts, A J; Weaver, A D; Daniel, J A</p> <p>2010-12-01</p> <p>The objective of this research was to determine if BPI Processing Technology (BPT) improved palatability of normal (NN) and callipyge (CN) <span class="hlt">lamb</span> meat and to determine the mechanism by which palatability was improved. Ten ewe and 10 wether <span class="hlt">lambs</span> of each phenotype were slaughtered, and carcass traits were assessed by a trained evaluator. The LM was removed at 2 d postmortem. Alternating sides served as controls (CON) or were treated with BPT. Muscles designated BPT were injected to a target 120% by weight with a patented solution containing water, ammonium hydroxide, carbon monoxide, and salt. Muscle pH, cooking loss, Warner-Bratzler shear force (WBS), sarcomere length, cooked moisture retention, and desmin degradation were measured. A trained sensory panel and a take-home consumer panel evaluated LM chops. Callipyge had a heavier BW and HCW, less adjusted fat thickness, reduced yield grades, and greater conformation scores than NN (P < 0.05). For LM, NN had shorter sarcomeres, smaller WBS values, greater juiciness ratings, more off-flavors, reduced consumer ratings for raw characteristics (like of portion size, like of color, like of leanness, overall like of appearance) and greater consumer ratings for eating characteristics (like of juiciness, like of flavor) than CN (P < 0.05). For LM, BPT had greater cooked moisture retention, smaller WBS values, greater juiciness ratings, less off-flavors, and greater consumer ratings for raw characteristics (like of portion size, like of color, overall like of appearance) and eating characteristics (like of juiciness, like of flavor) than CON (P < 0.05). Significant phenotype × treatment interactions occurred for LM muscle pH, desmin degradation, tenderness, consumer like of texture/tenderness, and consumer overall like of eating quality (P < 0.05). For LM, BPT increased muscle pH more for NN than CN (P < 0.01) and increased desmin degradation for NN but decreased desmin degradation for CN (P < 0.01). The BPT enhancement</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20060037198&hterms=water+jet+ultrasonic+water+jet&qs=N%3D0%26Ntk%3DAll%7CTitle%26Ntx%3Dmode%2Bmatchall%257Cmode%2Bmatchall%26Ntt%3Dwater%2Bjet%257Cultrasonic','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20060037198&hterms=water+jet+ultrasonic+water+jet&qs=N%3D0%26Ntk%3DAll%7CTitle%26Ntx%3Dmode%2Bmatchall%257Cmode%2Bmatchall%26Ntt%3Dwater%2Bjet%257Cultrasonic"><span id="translatedtitle">Nondestructive Determination of Heat/Fire Damage to Polymer - Matrix Composites Using Obliquely Insonified Ultrasonic <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bar-Cohen, Y.; Lih, S-S.; Mal, A. K.</p> <p>1995-01-01</p> <p>Reported on is the development of a quantitative NDE method, using stiffness analysis, for the determination of the degradation of composite materials that are exposed to elevated temperatures, prior to the formation of delaminations or other defects. Methods of testing describe a specimen immersed in water and subjected to ultra- sound, with reflected pulses or tone-burst (leaky <span class="hlt">Lamb</span> <span class="hlt">wave</span>) analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JPhA...29.5347K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JPhA...29.5347K"><span id="translatedtitle">Kinetics of a diffusive capture process: <span class="hlt">lamb</span> besieged by a pride of lions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krapivsky, P. L.; Redner, S.</p> <p>1996-09-01</p> <p>The survival probability, 0305-4470/29/17/011/img5, of a diffusing prey (`<span class="hlt">lamb</span>') in the proximity of N diffusing predators (a `pride of lions') in one dimension is investigated. When the lions are all to one side of the <span class="hlt">lamb</span>, the survival probability decays as a non-universal power law, 0305-4470/29/17/011/img6, with the decay exponent 0305-4470/29/17/011/img7 proportional to 0305-4470/29/17/011/img8. The crossover behaviour as a function of the relative diffusivities of the lions and the <span class="hlt">lamb</span> is also discussed. When 0305-4470/29/17/011/img9, the <span class="hlt">lamb</span> survival probability exhibits a log-normal decay, 0305-4470/29/17/011/img10.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22704960','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22704960"><span id="translatedtitle">Effects of two transport systems on <span class="hlt">lamb</span> welfare and meat quality.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miranda-de la Lama, G C; Salazar-Sotelo, M I; Pérez-Linares, C; Figueroa-Saavedra, F; Villarroel, M; Sañudo, C; Maria, G A</p> <p>2012-12-01</p> <p>The aim of this study was to analyse the effect of a direct transport system (DTS) versus transport with a logistic stopover system (TLS) on <span class="hlt">lamb</span> welfare and meat quality at two seasons. A total of 96 <span class="hlt">lambs</span> were sampled in a 2×2×2 factorial design, testing two transport systems and two seasons (summer and winter), with two replicates in each season. Significant interactions (P≤0.05) between transport system and season in both welfare and meat quality were found. In general, <span class="hlt">lambs</span> subjected to direct transport and logistic stopover during winter had a more intense stress response and poorer meat quality than <span class="hlt">lambs</span> transported during summer. However, direct transport during the cold season seemed to be the most stressful, compared to the rest of the groups, which was reflected in significantly higher levels of cortisol, lactate, glucose, ratio of N/L, higher pH24 and darker and tougher meat. PMID:22704960</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8938850','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8938850"><span id="translatedtitle">Response of Dorper and red Maasai <span class="hlt">lambs</span> to trickle Haemonchus contortus infections.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mugambi, J M; Wanyangu, S W; Bain, R K; Owango, M O; Duncan, J L; Stear, M J</p> <p>1996-11-01</p> <p>Six-month-old red Maasai <span class="hlt">lambs</span> were more resistant than Dorper <span class="hlt">lambs</span> to repeated infections at one to two week intervals with 1000 Haemonchus contortus infective larvae. Resistance after infection was assessed by means of faecal egg counts, packed cell volumes, eosinophil counts, total serum protein concentrations and mortality rates. The weight gains of the infected animals were only marginally lower than those of their uninfected controls, most probably because of their significantly higher feed consumption, and evidently the infected <span class="hlt">lambs</span> were not utilising all of the extra feed for growth. This absence of anorexia in spite of the infection was probably due to the palatability of the high protein diet fed to the <span class="hlt">lambs</span>. PMID:8938850</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25842304','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25842304"><span id="translatedtitle">Fatty acids and oxidative stability of meat from <span class="hlt">lambs</span> fed carob-containing diets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gravador, Rufielyn S; Luciano, Giuseppe; Jongberg, Sisse; Bognanno, Matteo; Scerra, Manuel; Andersen, Mogens L; Lund, Marianne N; Priolo, Alessandro</p> <p>2015-09-01</p> <p>Male Comisana <span class="hlt">lambs</span> were individually stalled and, for 56 days, were fed concentrates with 60% barley (n = 8 <span class="hlt">lambs</span>), or concentrates in which barley was partially replaced by 24% or 35% carob pulp (n = 9 <span class="hlt">lambs</span> in each group). The intramuscular fatty acids were analyzed and the color stability, lipid and protein oxidation were measured in fresh meat overwrapped with polyvinyl chloride film at 0, 3 or 6 days of storage at 4 °C in the dark. Carob pulp increased the concentration of polyunsaturated fatty acids (PUFA) in muscle, including the rumenic acid (P < 0.01), and reduced the saturated fatty acids (P < 0.01) and the n-6/n-3 PUFA ratio (P = 0.01). The meat did not undergo extensive oxidative deterioration and the diet did not affect the oxidative stability parameters. Therefore, carob in <span class="hlt">lamb</span> diet could increase PUFA in muscle without compromising meat oxidative stability. PMID:25842304</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S23C2753W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S23C2753W"><span id="translatedtitle"><span class="hlt">Wave</span>-equation migration velocity inversion using passive seismic sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Witten, B.; Shragge, J. C.</p> <p>2015-12-01</p> <p>Seismic monitoring at injection sites (e.g., CO2 sequestration, waste water disposal, hydraulic fracturing) has become an increasingly important tool for hazard identification and avoidance. The information obtained from this data is often limited to seismic event properties (e.g., location, approximate time, moment tensor), the accuracy of which greatly depends on the estimated elastic velocity models. However, creating accurate velocity models from passive array data remains a challenging problem. Common techniques rely on picking arrivals or matching waveforms requiring high signal-to-noise data that is often not available for the magnitude earthquakes observed over injection sites. We present a new method for obtaining elastic velocity information from earthquakes though full-wavefield <span class="hlt">wave</span>-equation imaging and adjoint-state tomography. The technique exploits the fact that the P- and S-<span class="hlt">wave</span> arrivals originate at the same time and location in the subsurface. We generate image volumes by back-propagating P- and S-<span class="hlt">wave</span> data through initial Earth models and then applying a correlation-based extended-imaging condition. Energy focusing away from zero lag in the extended image volume is used as a (penalized) residual in an adjoint-state tomography scheme to update the P- and S-<span class="hlt">wave</span> velocity models. We use an <span class="hlt">acousto-elastic</span> approximation to greatly reduce the computational cost. Because the method requires neither an initial source location or origin time estimate nor picking of arrivals, it is suitable for low signal-to-noise datasets, such as microseismic data. Synthetic results show that with a realistic distribution of microseismic sources, P- and S-velocity perturbations can be recovered. Although demonstrated at an oil and gas reservoir scale, the technique can be applied to problems of all scales from geologic core samples to global seismology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22472436','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22472436"><span id="translatedtitle">Theory of the <span class="hlt">Lamb</span> shift in muonic helium ions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Krutov, A. A.; Martynenko, A. P. Martynenko, G. A.; Faustov, R. N.</p> <p>2015-01-15</p> <p>The <span class="hlt">Lamb</span> shift (2P{sub 1/2}-2S{sub 1/2}) in muonic helium ions (μ{sub 2}{sup 3}){sup +}, (μ{sup 2/4}He){sup +} is calculated taking into account the contributions of the order of α{sup 3}, α{sup 4}, α{sup 5}, and α{sup 6}. Special attention is paid to corrections for the polarization of the vacuum, as well as the structure and recoil of the nucleus. Numerical values 1259.8583 meV ((μ{sub 2}{sup 3}He){sup +}) and 1379.1107 meV ((μ{sub 2}{sup 4}He){sup +}) obtained for the shifts can be considered reliable estimates when compared to the experimental data of the CREMA collaboration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/3088913','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/3088913"><span id="translatedtitle">Measurement of respiratory water loss in newborn <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hammarlund, K; Riesenfeld, T; Sedin, G</p> <p>1986-05-01</p> <p>A flow-through system for measurement of respiratory water loss, providing data on oxygen consumption and carbon dioxide production, is described. The system uses a mass spectrometer, specially equipped with a water channel, for analysis of gas concentrations. To avoid condensation of water vapour, the tubing in the flow-through system is heated. The method was tested by evaporating known amounts of water, and was found to be very accurate with a correlation coefficient of 0.999. Measurements were made in 10 fullterm <span class="hlt">lambs</span> of varying postnatal age (4-15 days) and a mean respiratory water loss (RWL) of 11.7 mg kg-1 min-1 was found at rest. The RWL decreased with increasing postnatal age, as did oxygen consumption. The RWL at rest was influenced by the ambient relative humidity, with higher values at lower humidities. PMID:3088913</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24210414','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24210414"><span id="translatedtitle">Nondestructive evaluation of helicopter rotor blades using guided <span class="hlt">Lamb</span> modes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chakrapani, Sunil Kishore; Barnard, Daniel; Dayal, Vinay</p> <p>2014-03-01</p> <p>This paper presents an application for turning and direct modes in a complex composite laminate structure. The propagation and interaction of turning modes and fundamental <span class="hlt">Lamb</span> modes are investigated in the skin, spar and web sections of a helicopter rotor blade. Finite element models were used to understand the various mode conversions at geometric discontinuities such as web-spar joints. Experimental investigation was carried out with the help of air coupled ultrasonic transducers. The turning and direct modes were confirmed with the help of particle displacements and velocities. Experimental B-Scans were performed on damaged and undamaged samples for qualitative and quantitative assessment of the structure. A strong correlation between the numerical and experimental results was observed and reported. PMID:24210414</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26618945','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26618945"><span id="translatedtitle">Michael E. <span class="hlt">Lamb</span>: Award for Distinguished Scientific Applications of Psychology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p></p> <p>2015-11-01</p> <p>The APA Award for Distinguished Scientific Applications of Psychology is presented to a person who, in the opinion of the Committee on Scientific Awards, has made distinguished theoretical or empirical advances leading to the understanding or amelioration of important practical problems. The 2015 recipient is Michael E. <span class="hlt">Lamb</span>, who "has significantly advanced understanding of the developmental and contextual factors affecting the delivery and impact of child care in the early years of life; the role of parent-child relationships in development; and the cognitive, emotional, and social factors affecting the quality of children's testimony, especially in cases of sexual and physical abuse." award citation, biography, and a selected bibliography are presented here. PMID:26618945</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1395580','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1395580"><span id="translatedtitle">Thyroxine utilization in the new-born <span class="hlt">lamb</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nathanielsz, P. W.</p> <p>1970-01-01</p> <p>1. From previous studies on foetal thyroid function in various mammalian species it would appear that the foetal pituitary—thyroid axis is capable of function before birth. Few studies are available to indicate the level of function before birth and in the immediate post-natal period. 2. Plasma thyroxine levels, thyroxine pool and utilization rate of thyroxine have been followed in new-born Welsh mountain <span class="hlt">lambs</span> from birth to 39 days of age. 3. Plasma thyroxine levels are high within the first hour of life after birth (18·2 ± 2·0 μg/100 ml.) and fall steadily to a minimum of 5·1 ± 1·1 on day 11 and 12 of post-natal life. Thereafter they fluctuate about a mean of 6·1 μg/100 ml. The significance of these changes is discussed in respect to foetal thyroxine levels, placental permeability to thyroxine, and foetal and neonatal thyroid and pituitary function. 4. Thyroxine utilization rate is high both in absolute terms and relative to unit body weight on days 1-4 of post-natal life. The utilization rate/kg remains fairly constant from days 10-39 of post-natal life. 5. Thyroxine utilization in the new-born <span class="hlt">lamb</span> is compared with that in the new-born calf in which the post-natal growth curve is very different. 6. The various factors such as levels of free thyroxine, diet and environmental changes which influence thyroxine utilization are discussed and the rate of utilization is compared with other indices of thyroid function in new-born and adult animals of different species. PMID:5500989</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26528248','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26528248"><span id="translatedtitle">Rumen microbial communities influence metabolic phenotypes in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Morgavi, Diego P; Rathahao-Paris, Estelle; Popova, Milka; Boccard, Julien; Nielsen, Kristian F; Boudra, Hamid</p> <p>2015-01-01</p> <p>The rumen microbiota is an essential part of ruminants shaping their nutrition and health. Despite its importance, it is not fully understood how various groups of rumen microbes affect host-microbe relationships and functions. The aim of the study was to simultaneously explore the rumen microbiota and the metabolic phenotype of <span class="hlt">lambs</span> for identifying host-microbe associations and potential biomarkers of digestive functions. Twin <span class="hlt">lambs</span>, separated in two groups after birth were exposed to practices (isolation and gavage with rumen fluid with protozoa or protozoa-depleted) that differentially restricted the acquisition of microbes. Rumen microbiota, fermentation parameters, digestibility and growth were monitored for up to 31 weeks of age. Microbiota assembled in isolation from other ruminants lacked protozoa and had low bacterial and archaeal diversity whereas digestibility was not affected. Exposure to adult sheep microbiota increased bacterial and archaeal diversity independently of protozoa presence. For archaea, Methanomassiliicoccales displaced Methanosphaera. Notwithstanding, protozoa induced differences in functional traits such as digestibility and significantly shaped bacterial community structure, notably Ruminococcaceae and Lachnospiraceae lower up to 6 folds, Prevotellaceae lower by ~40%, and Clostridiaceae and Veillonellaceae higher up to 10 folds compared to microbiota without protozoa. An orthogonal partial least squares-discriminant analysis of urinary metabolome matched differences in microbiota structure. Discriminant metabolites were mainly involved in amino acids and protein metabolic pathways while a negative interaction was observed between methylotrophic methanogens Methanomassiliicoccales and trimethylamine N-oxide. These results stress the influence of gut microbes on animal phenotype and show the potential of metabolomics for monitoring rumen microbial functions. PMID:26528248</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3628983','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3628983"><span id="translatedtitle">Unpredictable Feeding Impairs Glucose Tolerance in Growing <span class="hlt">Lambs</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jaquiery, Anne L.; Oliver, Mark H.; Landon-Lane, Nina; Matthews, Samuel J.; Harding, Jane E.; Bloomfield, Frank H.</p> <p>2013-01-01</p> <p>Irregular eating is associated with insulin resistance and metabolic disease in adults but may affect young, growing children differently. We investigated the metabolic effects of unpredictable feeding in female juvenile <span class="hlt">lambs</span> randomly assigned to receive, for six weeks, maintenance feed given twice daily in equal portions (Control Group, C; n = 24) or the same weekly feed amount in aliquots of variable size at unpredictable times (Unpredictable Group, U; n = 21). Intravenous glucose tolerance tests (IVGTT), insulin tolerance tests (ITT), and measurement of diurnal plasma cortisol concentrations were performed pre and post the dietary intervention. Groups were compared using t test and RM ANOVA. Weight gain was similar in both groups (C 18±2%; U 16±2% of initial body weight). Glucose area under the curve (AUC) was unchanged in C (AUC pre 818±34, post 801±33 mmol.min.l−1), but increased by 20% in U (pre 830±25, post 1010±19 mmol.min.l−1; p<0.0001), with an inadequate insulin response to glucose load (log(AUC insulin first 40 minutes) post intervention C 1.49±0.04 vs U 1.36±0.04 ng.min.ml−1; p = 0.03). Insulin tolerance and diurnal variation of plasma cortisol concentrations were not different between groups. Unpredictable feeding impairs insulin response to glucose in growing <span class="hlt">lambs</span> despite high quality food and normal weight gain. Irregular eating warrants investigation as a potentially remediable risk factor for disordered glucose metabolism. PMID:23613779</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4601264','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4601264"><span id="translatedtitle">Rumen microbial communities influence metabolic phenotypes in <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Morgavi, Diego P.; Rathahao-Paris, Estelle; Popova, Milka; Boccard, Julien; Nielsen, Kristian F.; Boudra, Hamid</p> <p>2015-01-01</p> <p>The rumen microbiota is an essential part of ruminants shaping their nutrition and health. Despite its importance, it is not fully understood how various groups of rumen microbes affect host-microbe relationships and functions. The aim of the study was to simultaneously explore the rumen microbiota and the metabolic phenotype of <span class="hlt">lambs</span> for identifying host-microbe associations and potential biomarkers of digestive functions. Twin <span class="hlt">lambs</span>, separated in two groups after birth were exposed to practices (isolation and gavage with rumen fluid with protozoa or protozoa-depleted) that differentially restricted the acquisition of microbes. Rumen microbiota, fermentation parameters, digestibility and growth were monitored for up to 31 weeks of age. Microbiota assembled in isolation from other ruminants lacked protozoa and had low bacterial and archaeal diversity whereas digestibility was not affected. Exposure to adult sheep microbiota increased bacterial and archaeal diversity independently of protozoa presence. For archaea, Methanomassiliicoccales displaced Methanosphaera. Notwithstanding, protozoa induced differences in functional traits such as digestibility and significantly shaped bacterial community structure, notably Ruminococcaceae and Lachnospiraceae lower up to 6 folds, Prevotellaceae lower by ~40%, and Clostridiaceae and Veillonellaceae higher up to 10 folds compared to microbiota without protozoa. An orthogonal partial least squares-discriminant analysis of urinary metabolome matched differences in microbiota structure. Discriminant metabolites were mainly involved in amino acids and protein metabolic pathways while a negative interaction was observed between methylotrophic methanogens Methanomassiliicoccales and trimethylamine N-oxide. These results stress the influence of gut microbes on animal phenotype and show the potential of metabolomics for monitoring rumen microbial functions. PMID:26528248</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=286341','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=286341"><span id="translatedtitle">Intake of honey mesquite (Prosopis glandulosa) leaves by <span class="hlt">lambs</span> using different levels of activated charcoal</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>A 24-day feeding trial was conducted to assess the effect of feeding four levels of activated charcoal (0.0, 0.33, 0.67 and 1.00 g/kg of body weight) on intake of honey mesquite leaves (Prosopis glandulosa Torr.) by 20 wether <span class="hlt">lambs</span> (36.6 ± 0.6 kg) that were randomly assigned to treatments. <span class="hlt">Lambs</span> wer...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8745744','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8745744"><span id="translatedtitle">Clinico-pathological observations on naturally occurring contagious ecthyma in <span class="hlt">lambs</span> in Saudi Arabia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gameel, A A; Abu Elzein, E M; Housawi, F M; Agib, A; Ibrahim, A O</p> <p>1995-01-01</p> <p>Typical lesions of contagious ecthyma were diagnosed in <span class="hlt">lambs</span> four months old and infection has been confirmed by viral isolation and identification. The <span class="hlt">lambs</span> had lower total serum protein values, haemoglobin concentration, erythrocyte counts and packed cell volume, but higher blood leukocyte counts and increased serum transaminase activity when compared to apparently healthy animals. The disease is believed to be transmitted from newly introduced goats which showed evidence of infection. PMID:8745744</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15737176','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15737176"><span id="translatedtitle">Effects of three anthelmintic regimes on milk yield of ewes and growth of <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fthenakis, G C; Papadopoulos, E; Himonas, C</p> <p>2005-03-01</p> <p>Forty ewes were allocated into one of four groups (n = 10) and were treated with albendazole (ALB) (3.8 mg kg(-1)) before <span class="hlt">lambing</span> (group A), with ALB before and after <span class="hlt">lambing</span> (group B), with moxidectin (MXD) (0.2 mg kg(-1)) before <span class="hlt">lambing</span> (group C) or were untreated controls (group D). Counts of nematode eggs in faeces and coprocultures were carried out during the study, as well as ewes' milk yield measurements and <span class="hlt">lamb</span> weighings. Pre-treatment mean eggs per gram (epg) counts were 640, 715, 625 and 630 for groups A, B, C and D, respectively (P > 0.05); respective counts 21 days after treatment were 5, 0, 0 and 690 epg, whilst 70 days after treatment they were 380, 145, 40 and 1120 epg. Mean lactation milk yield was 3527.5, 3893.5, 3786.4 and 3285.9 ml for groups A, B, C and D, respectively; no significant difference was evident among the four groups in milk yield collected during the suckling period, although subsequently, group B or C ewes yielded significantly more milk than controls (P < 0.05). Mean birthweight of <span class="hlt">lambs</span> were 3.56, 3.45, 3.59 and 3.26 kg for groups A, B, C and D, respectively (P = 0.045); subsequently, <span class="hlt">lambs</span> from treated ewes were significantly heavier than <span class="hlt">lambs</span> from control animals (P < 0.001). We conclude that anti-parasitic treatment during the last month of pregnancy contributed to an increased birthweight of <span class="hlt">lambs</span> of treated ewes, whilst the cumulative effect of two doses of ALB or the long persistent efficacy of MXD provided a longer protection of animals against new parasitic infections and contributed to a lactation persistence. PMID:15737176</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4518504','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4518504"><span id="translatedtitle">The role of the environment in transmission of Dichelobacter nodosus between ewes and their <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Muzafar, Mohd; Calvo-Bado, Leo A.; Green, Laura E.; Smith, Edward M.; Russell, Claire L.; Grogono-Thomas, Rose; Wellington, Elizabeth M.H.</p> <p>2015-01-01</p> <p>Dichelobacter nodosus (D. nodosus) is the essential causative agent of footrot in sheep. The current study investigated when D. nodosus was detectable on newborn <span class="hlt">lambs</span> and possible routes of transmission. Specific qPCR was used to detect and quantify the load of D. nodosus in foot swabs of <span class="hlt">lambs</span> at birth and 5–13 h post-partum, and their mothers 5–13 h post-partum; and in samples of bedding, pasture, soil and faeces. D. nodosus was not detected on the feet of newborn <span class="hlt">lambs</span> swabbed at birth, but was detected 5–13 h after birth, once they had stood on bedding containing naturally occurring D. nodosus. Multiple genotypes identified by cloning and sequencing a marker gene, pgrA, and by multi locus variable number tandem repeat analysis (MLVA) of community DNA from swabs on individual feet indicated a mixed population of D. nodosus was present on the feet of both ewes and <span class="hlt">lambs</span>. There was high variation in pgrA tandem repeat number (between 3 and 21 repeats), and multiple MLVA types. The overall similarity index between the populations on ewes and <span class="hlt">lambs</span> was 0.45, indicating moderate overlap. Mother offspring pairs shared some alleles but not all, suggesting <span class="hlt">lambs</span> were infected from sources(s) other than just their mother's feet. We hypothesise that D. nodosus is transferred to the feet of <span class="hlt">lambs</span> via bedding containing naturally occurring populations of D. nodosus, probably as a result of transfer from the feet of the group of housed ewes. The results support the hypothesis that the environment plays a key role in the transmission of D. nodosus between ewes and <span class="hlt">lambs</span>. PMID:25953734</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27389751','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27389751"><span id="translatedtitle">Failure of maternal colostral antibody transfer in <span class="hlt">lambs</span> linked to excess dietary iodine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p></p> <p>2016-07-01</p> <p>Failure of maternal colostral antibody transfer in <span class="hlt">lambs</span>Hypomagnesaemia in calvesHyperplastic goitre in a stillborn calfAbortion storm in a beef herd due to Salmonella MontevideoRickets in hogg <span class="hlt">lambs</span>Staphylococcus hyicus isolated from piglets with joint ill These are among matters discussed in the disease surveillance report for March 2016 from SAC Consulting: Veterinary Services (SAC C VS). PMID:27389751</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25120032','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25120032"><span id="translatedtitle">Acute visceral cysticercosis by Taenia hydatigena in <span class="hlt">lambs</span> and treatment with praziquantel.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Scala, A; Urrai, G; Varcasia, A; Nicolussi, P; Mulas, M; Goddi, L; Pipia, A P; Sanna, G; Genchi, M; Bandino, E</p> <p>2016-01-01</p> <p>An acute outbreak of Taenia hydatigena cysticercosis, causing mortality in 5 of 21 (23.8%) female <span class="hlt">lambs</span>, is reported. Gross post-mortem examinations and histology showed Cysticercus tenuicollis as the cause of death. Biochemical parameters in infected <span class="hlt">lambs</span> confirmed severe hepatitis. Praziquantel, given once at 15 mg/kg body weight (bw), was administered and a dramatic improvement in the clinical condition and biochemical parameters was observed up to 30 days following treatment. PMID:25120032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15005388','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15005388"><span id="translatedtitle">Development of a Multi-Layer Guided <span class="hlt">Wave</span> Inspection Technique</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Quarry, M; Chinn, D; Hay, T</p> <p>2001-03-12</p> <p>This study investigates the inspection of a particular layer of a multi-layer structure using ultrasonic guided <span class="hlt">waves</span>. Techniques based on <span class="hlt">Lamb</span> <span class="hlt">waves</span> have been developed for the inspection of plate structures and are well understood. Guided <span class="hlt">waves</span> also exist in multi-layered plates as well. Energy distributions vary across the thickness of a multi-layer structure depending on the mode and frequency. Hence, a potential way to inspect the bottom layer of a structure is to find modes with sufficient energy in the bottom layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24950082','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24950082"><span id="translatedtitle">The impact of supplementing <span class="hlt">lambs</span> with algae on growth, meat traits and oxidative status.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hopkins, D L; Clayton, E H; Lamb, T A; van de Ven, R J; Refshauge, G; Kerr, M J; Bailes, K; Lewandowski, P; Ponnampalam, E N</p> <p>2014-10-01</p> <p>The current study examined the effect of supplementing <span class="hlt">lambs</span> with algae. Forty, three month old <span class="hlt">lambs</span> were allocated to receive a control ration based on oats and lupins (n=20) or the control ration with DHA-Gold™ algae (~2% of the ration, n=20). These <span class="hlt">lambs</span> came from dams previously fed a ration based on either silage (high in omega-3) or oats and cottonseed meal (OCSM: high in omega-6) at joining (dam nutrition, DN). <span class="hlt">Lamb</span> performance, carcase weight and GR fat content were not affected by treatment diet (control vs algae) or DN (silage vs OSCM). Health claimable omega-3 fatty acids (EPA+DHA) were significantly greater in the LL of <span class="hlt">lambs</span> fed algae (125±6mg/100g meat) compared to those not fed algae (43±6mg/100g meat) and this effect was mediated by DN. Supplementing with algae high in DHA provides a means of improving an aspect of the health status of <span class="hlt">lamb</span> meat. PMID:24950082</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=370577','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=370577"><span id="translatedtitle">Duration and characteristics of treatment of premature <span class="hlt">lambs</span> with natural surfactant.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jobe, A; Ikegami, M; Glatz, T; Yoshida, Y; Diakomanolis, E; Padbury, J</p> <p>1981-01-01</p> <p>Premature <span class="hlt">lambs</span> were treated with 50 mg/kg of natural surfactant lipid by tracheal instillation either at birth or shortly thereafter when respiratory failure was documented. All <span class="hlt">lambs</span> were delivered by cesarean section and supported on infant ventilators with 100% oxygen under conditions to mimic the care of human infants with the respiratory distress syndrome. The natural surfactant used for therapy was recovered by lavage from sheep lung. Six 120-d gestational age <span class="hlt">lambs</span> treated at birth had an initial mean oxygen pressure (pO2) value of 270 +/- 35 mm Hg; this fell within 3 h to less than 100 mm Hg. By 8.3 +/- 0.3 h after birth the <span class="hlt">lambs</span> were in severe respiratory failure with a mean pH less than 7.1 and a mean pCO2 greater than 70 mm Hg. Six untreated <span class="hlt">lambs</span> had pH values below 7.0 within 40 min of life despite more intensive respiratory support than was given the treated animals. Treatment with natural surfactant of 17 <span class="hlt">lambs</span> of 120 and 130 d gestational age after early respiratory failure resulted in a prompt increase in pO2 values from about 35 mm Hg to values over 200 mm Hg and a fall in pCO2 values to normal levels in the majority of animals. This response lasted only approximately 3 h, and a second treatment was less predictably effective. PMID:6780608</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27576848','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27576848"><span id="translatedtitle">Effects of early feeding on the host rumen transcriptome and bacterial diversity in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Weimin; Li, Chong; Li, Fadi; Wang, Xiaojuan; Zhang, Xiaoxue; Liu, Ting; Nian, Fang; Yue, Xiangpeng; Li, Fei; Pan, Xiangyu; La, Yongfu; Mo, Futao; Wang, Fangbin; Li, Baosheng</p> <p>2016-01-01</p> <p>Early consumption of starter feed promotes rumen development in <span class="hlt">lambs</span>. We examined rumen development in <span class="hlt">lambs</span> fed starter feed for 5 weeks using histological and biochemical analyses and by performing high-throughput sequencing in rumen tissues. Additionally, rumen contents of starter feed-fed <span class="hlt">lambs</span> were compared to those of breast milk-fed controls. Our physiological and biochemical findings revealed that early starter consumption facilitated rumen development, changed the pattern of ruminal fermentation, and increased the amylase and carboxymethylcellulase activities of rumen micro-organisms. RNA-seq analysis revealed 225 differentially expressed genes between the rumens of breast milk- and starter feed-fed <span class="hlt">lambs</span>. These DEGs were involved in many metabolic pathways, particularly lipid and carbohydrate metabolism, and included HMGCL and HMGCS2. Sequencing analysis of 16S rRNA genes revealed that ruminal bacterial communities were more diverse in breast milk-than in starter feed-fed <span class="hlt">lambs</span>, and each group had a distinct microbiota. We conclude that early starter feeding is beneficial to rumen development and physiological function in <span class="hlt">lambs</span>. The underlying mechanism may involve the stimulation of ruminal ketogenesis and butanoate metabolism via HMGCL and HMGCS2 combined with changes in the fermentation type induced by ruminal microbiota. Overall, this study provides insights into the molecular mechanisms of rumen development in sheep. PMID:27576848</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4108057','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4108057"><span id="translatedtitle">The effect of colostrum intake on blood plasma proteome profile in newborn <span class="hlt">lambs</span>: low abundance proteins</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>Background Colostrum intake by newborn <span class="hlt">lambs</span> plays a fundamental role in the perinatal period, ensuring <span class="hlt">lamb</span> survival. In this study, blood plasma samples from two groups of newborn <span class="hlt">lambs</span> (Colostrum group and Delayed Colostrum group) at 2 and 14 h after birth were treated to reduce the content of high abundance proteins and analyzed using Two-Dimensional Differential in Gel Electrophoresis and MALDI MS/MS for protein identification in order to investigate low abundance proteins with immune function in newborn <span class="hlt">lambs</span>. Results The results showed that four proteins were increased in the blood plasma of <span class="hlt">lambs</span> due to colostrum intake. These proteins have not been previously described as increased in blood plasma of newborn ruminants by colostrum intake. Moreover, these proteins have been described as having an immune function in other species, some of which were previously identified in colostrum and milk. Conclusions In conclusion, colostrum intake modified the low abundance proteome profile of blood plasma from newborn <span class="hlt">lambs</span>, increasing the concentration of apolipoprotein A-IV, plasminogen, serum amyloid A and fibrinogen, demonstrating that colostrum is essential, not only for the provision of immunoglobulins, but also because of increases in several low abundance proteins with immune function. PMID:24708841</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5006043','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5006043"><span id="translatedtitle">Effects of early feeding on the host rumen transcriptome and bacterial diversity in <span class="hlt">lambs</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Weimin; Li, Chong; Li, Fadi; Wang, Xiaojuan; Zhang, Xiaoxue; Liu, Ting; Nian, Fang; Yue, Xiangpeng; Li, Fei; Pan, Xiangyu; La, Yongfu; Mo, Futao; Wang, Fangbin; Li, Baosheng</p> <p>2016-01-01</p> <p>Early consumption of starter feed promotes rumen development in <span class="hlt">lambs</span>. We examined rumen development in <span class="hlt">lambs</span> fed starter feed for 5 weeks using histological and biochemical analyses and by performing high-throughput sequencing in rumen tissues. Additionally, rumen contents of starter feed-fed <span class="hlt">lambs</span> were compared to those of breast milk-fed controls. Our physiological and biochemical findings revealed that early starter consumption facilitated rumen development, changed the pattern of ruminal fermentation, and increased the amylase and carboxymethylcellulase activities of rumen micro-organisms. RNA-seq analysis revealed 225 differentially expressed genes between the rumens of breast milk- and starter feed-fed <span class="hlt">lambs</span>. These DEGs were involved in many metabolic pathways, particularly lipid and carbohydrate metabolism, and included HMGCL and HMGCS2. Sequencing analysis of 16S rRNA genes revealed that ruminal bacterial communities were more diverse in breast milk-than in starter feed-fed <span class="hlt">lambs</span>, and each group had a distinct microbiota. We conclude that early starter feeding is beneficial to rumen development and physiological function in <span class="hlt">lambs</span>. The underlying mechanism may involve the stimulation of ruminal ketogenesis and butanoate metabolism via HMGCL and HMGCS2 combined with changes in the fermentation type induced by ruminal microbiota. Overall, this study provides insights into the molecular mechanisms of rumen development in sheep. PMID:27576848</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26894501','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26894501"><span id="translatedtitle">Vitamin E supplementation of undernourished ewes pre- and post-<span class="hlt">lambing</span> reduces weight loss of ewes and increases weight of <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rosales Nieto, César Augusto; Meza-Herrera, César Alberto; Moron Cedillo, Felipe de Jesús; Flores Najera, Manuel de Jesús; Gámez Vázquez, Hector Guillermo; Ventura Pérez, Felipe de Jesús; Liu, Shimin</p> <p>2016-03-01</p> <p>The aim of this study was to test if vitamin E supplementation during late gestation and early lactation would affect the weight of ewes under nutritional restriction and the performance of their <span class="hlt">lambs</span>. Mature Rambouillet ewes (n = 37) were fed a diet that supplied 70 % of the energy and 80 % of recommended protein requirements and randomly assigned to either vitamin E (vit E, n = 20, 4 IU of α-tocopherol kg(-1) of live weight) or control (n = 17, without vitamin E supplementation). During the experimental period, the mean weight of ewes decreased from 74.6 ± 2.4 to 58.1 ± 2.2 kg. Weight loss of ewes was slightly less for the vit E than the control (-65 vs -124 g day(-1), SEM = 46; P = 0.07). <span class="hlt">Lambs</span> born from vit E-supplemented ewes were heavier than <span class="hlt">lambs</span> from the control and grew significantly faster (239 vs 195 g day(-1), SEM = 29.3, P < 0.05) with heavier weights at weaning (16.5 vs 13.5 kg, SEM = 1.8, P < 0.05). Besides, birth weight, weaning weight and daily weight gain favoured to single <span class="hlt">lambs</span> and to male <span class="hlt">lambs</span> (P < 0.05). Weaning weight was positively correlated to birth weight (P < 0.05) and weight gain (P < 0.001). When the nutrient requirements for ewes are not met, supplementation of vitamin E during late gestation and early lactation might be an effective strategy to minimise ewe weight loss as well as to increase <span class="hlt">lamb</span> growth. PMID:26894501</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22871584','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22871584"><span id="translatedtitle">Effect of straw on <span class="hlt">lamb</span> welfare, production performance and meat quality during the finishing phase of fattening.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Teixeira, D L; Miranda-de la Lama, G C; Villarroel, M; Garcia-Belenguer, S; Sañudo, C; Maria, G A</p> <p>2012-12-01</p> <p>The studies analyse the effect of straw on <span class="hlt">lamb</span> welfare, production and meat quality in finishing <span class="hlt">lambs</span>. Two studies were carried out. Study 1 included two treatments and two replicates with six <span class="hlt">lambs</span> each (17.20±0.2 kg). One pen was provided with straw for forage and bedding while the other had none. Feeding with concentrate was ad libitum. Live weight and concentrate consumption were recorded and average daily gain and conversion index calculated. Stereotypes, agonistic and affiliative interactions and physiological indicators of stress were analysed. In study 2, 24 <span class="hlt">lambs</span> were divided into two groups to analyse the effect of treatments on meat and carcass quality. No significant differences in production or meat quality traits were observed. <span class="hlt">Lambs</span> housed without straw had higher levels of cortisol and stereotypes. Affiliative interactions were greater in <span class="hlt">lambs</span> without straw. Results suggest that straw can be considered an effective environment-enriching tool to improve welfare. PMID:22871584</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JPhCS.305a2088K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JPhCS.305a2088K"><span id="translatedtitle">Wireless power transmission using ultrasonic guided <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kural, A.; Pullin, R.; Featherston, C.; Paget, C.; Holford, K.</p> <p>2011-07-01</p> <p>The unavailability of suitable power supply at desired locations is currently an important obstacle in the development of distributed, wireless sensor networks for applications such as structural health monitoring of aircraft. Proposed solutions range from improved batteries to energy harvesting from vibration, temperature gradients and other sources. A novel approach is being investigated at Cardiff University School of Engineering in cooperation with Airbus. It aims to utilise ultrasonic guided <span class="hlt">Lamb</span> <span class="hlt">waves</span> to transmit energy through the aircraft skin. A vibration generator is to be placed in a location where electricity supply is readily available. Ultrasonic <span class="hlt">waves</span> generated by this device will travel through the aircraft structure to a receiver in a remote wireless sensor node. The receiver will convert the mechanical vibration of the ultrasonic <span class="hlt">waves</span> back to electricity, which will be used to power the sensor node. This paper describes the measurement and modelling of the interference pattern which emerges when <span class="hlt">Lamb</span> <span class="hlt">waves</span> are transmitted continuously as in this power transmission application. The discovered features of the pattern, such as a large signal amplitude variation and a relatively high frequency, are presented and their importance for the development of a power transmission system is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=207716','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=207716"><span id="translatedtitle">Stoichiometry of maltodextrin-binding sites in <span class="hlt">LamB</span>, an outer membrane protein from Escherichia coli.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gehring, K; Cheng, C H; Nikaido, H; Jap, B K</p> <p>1991-01-01</p> <p>We have directly measured the stoichiometry of maltodextrin-binding sites in <span class="hlt">LamB</span>. Scatchard plots and computer fitting of flow dialysis (rate-of-dialysis) experiments clearly establish three independent binding sites per <span class="hlt">LamB</span> trimer, with a dissociation constant of approximately 60 microM for maltoheptaose. The current model for <span class="hlt">LamB</span>'s function as a specific pore is discussed with respect to the symmetry in <span class="hlt">LamB</span>'s kinetic properties and the implications of our results. Images PMID:2001992</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16085365','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16085365"><span id="translatedtitle">Interaction between copper oxide wire particles and Duddingtonia flagrans in <span class="hlt">lambs</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burke, J M; Miller, J E; Larsen, M; Terrill, T H</p> <p>2005-11-25</p> <p>An experiment was completed to determine if copper oxide wire particles (COWP) had any effect on the activity of the nematode-trapping fungus Duddingtonia flagrans in growing <span class="hlt">lambs</span>. COWP has been used recently as a dewormer in small ruminants because of nematode resistance to anthelmintics. D. flagrans has been used to control free-living stages of parasitic nematodes in livestock. Katahdin and Dorper <span class="hlt">lambs</span>, 4 months of age, were administered no or 4 g COWP (n=24/dose) in early October 2003. Haemonchus contortus was the predominant gastrointestinal parasite during the trial, which was acquired naturally from pasture. Half the <span class="hlt">lambs</span> from each COWP group were supplemented with corn/soybean meal with or without D. flagrans for 35 days. Fecal egg counts (FEC) and packed cell volume (PCV) were determined weekly between days 0 (day of COWP administration) and 35. Feces from <span class="hlt">lambs</span> in each treatment group were pooled and three replicates per group were cultured for 14 days at room temperature. Larvae (L3) were identified and counted per gram of feces cultured. Treatment with COWP was effective in decreasing FEC, which remained low compared with FEC from <span class="hlt">lambs</span> not treated with COWP. This led to an increase in PCV in these <span class="hlt">lambs</span> (COWP x day, P<0.001). Number of larvae was decreased in feces from <span class="hlt">lambs</span> treated with COWP and D. flagrans between days 14 and 35 compared to the other groups of <span class="hlt">lambs</span> (COWP x D. flagrans x day, P<0.003). Percentage of larvae identified as H. contortus decreased in feces collected from <span class="hlt">lambs</span> treated with COWP and D. flagrans between days 14 and 28 compared with other treatments (COWP x D. flagrans x day, P<0.05). Other trichostrongyles were present and remained less than 7% in feces collected from control <span class="hlt">lambs</span>. There was no adverse effect of COWP on the ability of D. flagrans to trap residual larvae after COWP treatment. With fewer eggs being excreted due to the effect of copper on H. contortus, and the additional larval reducing effect exerted by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JBO....21a5007A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JBO....21a5007A"><span id="translatedtitle">Photothermal ablation of liver tissue with 1940-nm thulium fiber laser: an ex vivo study on <span class="hlt">lamb</span> liver</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alagha, Heba Z.; Gülsoy, Murat</p> <p>2016-01-01</p> <p>The purpose of this study was to investigate the ablation efficiency of 1940-nm thulium fiber laser on liver tissue, while utilizing a real-time measurement system to monitor the temperature rise in adjacent tissues. Thulium fiber laser was delivered to <span class="hlt">lamb</span> liver tissue samples via 400-μm bare tip fiber in contact mode. Eight different laser parameter combinations [power, continuous-<span class="hlt">wave</span> (cw)/pulsed-modulated (pm) mode, and exposure time] were used. Exposure times were chosen to give the same total applied energy of 4 J for comparative purposes. Following laser irradiations, tissues were processed and stained with hematoxylin and eosin for macroscopic evaluation of ablation areas and total altered areas, and ablation efficiencies were calculated. Temperature of the nearby tissue at a distance of 1 mm from the fiber was measured, and rate of temperature change was calculated. A strong correlation between the rate of temperature change and ablation area was noted. Thermal effects increased with increasing power for both modes. The continuous-<span class="hlt">wave</span> mode yielded higher ablation efficiencies than the pulse-modulated mode. Histological evaluation revealed a narrow vacuolization zone and negligible carbonization for higher-power values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/10875625','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/10875625"><span id="translatedtitle">Preferences for foods varying in macronutrients and tannins by <span class="hlt">lambs</span> supplemented with polyethylene glycol.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Titus, C H; Provenza, F D; Perevolotsky, A; Silanikove, N</p> <p>2000-06-01</p> <p>Supplemental polyethylene glycol (PEG) increases intake when animals eat foods high in tannins, but little is known about how PEG affects preference for foods that vary in concentrations of macronutrients and tannin. We investigated how varying macronutrients and tannins (commercially available extracts from quebracho trees) affected food intake, and we assessed the degree to which PEG (MW 3350) affected intake of tannin-rich foods by sheep. From 0715 to 1800 daily, <span class="hlt">lambs</span> were offered diets that varied in concentrations of macronutrients: high energy/low protein (75% barley/25% alfalfa), medium energy/medium protein (35% barley/65% alfalfa), and low energy/high protein (100% alfalfa). Preference for these diets was determined in the absence of tannin, and then, in Trials 1 to 3, tannin was added in increasing concentrations (from 5 to 20%) to the diets with high and medium levels of energy. In Trial 4, tannin (10%) also was added to the low-energy diet. <span class="hlt">Lambs</span> were supplemented with either 50 g of PEG mixed with 50 g of ground barley or 50 g of ground barley alone from 0700 to 1715 daily; <span class="hlt">lambs</span> always consumed all of these supplements. In the absence of added tannins, all <span class="hlt">lambs</span> preferred high energy/low protein > medium energy/medium protein > low energy/high protein. As tannin levels increased, preference for the high- and medium-energy foods decreased, and all <span class="hlt">lambs</span> preferred foods that were lower in tannins and higher in protein. <span class="hlt">Lambs</span> supplemented with PEG ate more macronutrients and tannins than unsupplemented <span class="hlt">lambs</span>, and the effect became increasingly apparent as tannin levels increased from Trials 1 to 4. We conclude that the effectiveness of supplemental PEG may be low if alternative forages are equal or superior in nutritional quality and contain fewer metabolites with adverse effects. In such cases, animals would likely prefer alternatives to high-tannin foods. PMID:10875625</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24936027','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24936027"><span id="translatedtitle"><span class="hlt">Lamb</span> model of respiratory syncytial virus-associated lung disease: insights to pathogenesis and novel treatments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ackermann, Mark R</p> <p>2014-01-01</p> <p>Preterm birth is a risk factor for respiratory syncytial virus (RSV) bronchiolitis and hospitalization. The pathogenesis underlying this is not fully understood, and in vivo studies are needed to better clarify essential cellular features and molecular mechanisms. Such studies include analysis of lung tissue from affected human infants and various animal models. The preterm and newborn <span class="hlt">lamb</span> lung has developmental, structural, cellular, physiologic, and immunologic features similar to that of human infants. Also, the <span class="hlt">lamb</span> lung is susceptible to various strains of RSV that infect infants and cause similar bronchiolar lesions. Studies in <span class="hlt">lambs</span> suggest that viral replication in airways (especially bronchioles) is extensive by 4 days after infection, along with bronchiolitis characterized by degeneration and necrosis of epithelial cells, syncytial cell formation, neutrophil infiltration, epithelial cell hypertrophy and hyperplasia, and innate and adaptive immune responses. RSV bronchiolitis greatly affects airflow and gaseous exchange. RSV disease severity is increased in preterm <span class="hlt">lambs</span> compared with full-term <span class="hlt">lambs</span>; similar to human infants. The <span class="hlt">lamb</span> is conducive to experimental assessment of novel, mechanistic therapeutic interventions such as delivery of vascular endothelial growth factor and enhancement of airway epithelial oxidative responses, Club (Clara) cell protein 10, and synthesized compounds such as nanobodies. In contrast, exposure of the fetal ovine lung in vivo to ethanol, a risk factor for preterm birth, reduces pulmonary alveolar development and surfactant protein A expression. Because the formalin-inactivated RSV vaccination enhances some inflammatory responses to RSV infection in <span class="hlt">lambs</span>, this model has the potential to assess mechanisms of formalin-inactivated RSV enhanced disease as well as newly developed vaccines. PMID:24936027</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15032439','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15032439"><span id="translatedtitle">Prediction of <span class="hlt">lamb</span> carcass composition by impedance spectroscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Altmann, M; Pliquett, U; Suess, R; von Borell, E</p> <p>2004-03-01</p> <p>The objective of this study was to compare impedance spectroscopy with resistance measurements at a single frequency (50 kHz) for the prediction of <span class="hlt">lamb</span> carcass composition. The impedance spectrum is usually recorded by measuring the complex impedance at various frequencies (frequency domain); however, in this study, we also applied the faster and simpler measurement in the time domain (application of a current step and measurement of the voltage response). The study was carried out on 24 male, German Black-headed Mutton <span class="hlt">lambs</span> with an average BW of 45 kg. Frequency- and time domain-based impedance measurements were collected at 20 min and 24 h postmortem with different electrode placements. Real and imaginary parts at various frequencies were calculated from the locus diagram. Left sides were dissected into lean, fat, and bone, and right sides were ground to determine actual carcass composition. Crude fat, crude protein, and moisture were chemically analyzed on ground samples. Frequency- and time domain-based measurements did not provide the same absolute impedance values; however, the high correlations (P < 0.001) between these methods for the "real parts" showed that they ranked individuals in the same order. Most of the time domain data correlated higher to carcass composition than did the frequency domain data. The real parts of impedance showed correlations between -0.37 (P > 0.05) and -0.74 (P < 0.001) to water, crude fat, lean, and fatty tissue, whereas the relations to CP were much lower (from 0.00 to -0.47, P < 0.05). Electrode placements at different locations did not substantially improve the correlations with carcass composition. The "imaginary parts" of impedance were not suitable for the prediction of carcass composition. The highest accuracy (R2 = 0.66) was reached for the estimation of crude fat percentage by a regression equation with the time domain-based impedance measured at 24 h postmortem. Furthermore, there was not a clear superiority of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title16-vol1/pdf/CFR-2012-title16-vol1-sec301-8.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title16-vol1/pdf/CFR-2012-title16-vol1-sec301-8.pdf"><span id="translatedtitle">16 CFR 301.8 - Use of terms “Persian <span class="hlt">Lamb</span>,” “Broadtail <span class="hlt">Lamb</span>,” and “Persian-broadtail Lamb” permitted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>...,â and âPersian-broadtail <span class="hlt">Lamb</span>â permitted. 301.8 Section 301.8 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF CONGRESS RULES AND REGULATIONS UNDER FUR PRODUCTS LABELING ACT... breed of sheep or top-cross breed of such sheep, having flat light-weight fur with a moire pattern....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title16-vol1/pdf/CFR-2014-title16-vol1-sec301-8.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title16-vol1/pdf/CFR-2014-title16-vol1-sec301-8.pdf"><span id="translatedtitle">16 CFR 301.8 - Use of terms “Persian <span class="hlt">Lamb</span>,” “Broadtail <span class="hlt">Lamb</span>,” and “Persian-broadtail Lamb” permitted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... or top-cross breed of such sheep, having hair formed in knuckled curls. (b) The term Broadtail <span class="hlt">Lamb</span>... breed of sheep or top-cross breed of such sheep, having flat light-weight fur with a moire pattern. (c... breed of sheep or top-cross breed of such sheep, having hair formed in flattened knuckled curls with...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title16-vol1/pdf/CFR-2011-title16-vol1-sec301-8.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title16-vol1/pdf/CFR-2011-title16-vol1-sec301-8.pdf"><span id="translatedtitle">16 CFR 301.8 - Use of terms “Persian <span class="hlt">Lamb</span>,” “Broadtail <span class="hlt">Lamb</span>,” and “Persian-broadtail Lamb” permitted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... or top-cross breed of such sheep, having hair formed in knuckled curls. (b) The term Broadtail <span class="hlt">Lamb</span>... breed of sheep or top-cross breed of such sheep, having flat light-weight fur with a moire pattern. (c... breed of sheep or top-cross breed of such sheep, having hair formed in flattened knuckled curls with...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title16-vol1/pdf/CFR-2013-title16-vol1-sec301-8.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title16-vol1/pdf/CFR-2013-title16-vol1-sec301-8.pdf"><span id="translatedtitle">16 CFR 301.8 - Use of terms “Persian <span class="hlt">Lamb</span>,” “Broadtail <span class="hlt">Lamb</span>,” and “Persian-broadtail Lamb” permitted.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... or top-cross breed of such sheep, having hair formed in knuckled curls. (b) The term Broadtail <span class="hlt">Lamb</span>... breed of sheep or top-cross breed of such sheep, having flat light-weight fur with a moire pattern. (c... breed of sheep or top-cross breed of such sheep, having hair formed in flattened knuckled curls with...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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