bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ocular deficits associated with alcohol exposure during zebrafish development
Authors: Dlugos Cynthia A. , Rabin Richard A. 
Published: March 2007

AbstractApproximately 90% of fetal alcohol syndrome cases are accompanied by ocular abnormalities. The zebrafish (Danio rerio) is a well‐known developmental model that provides an opportunity for better understanding the histological and cytological effects of developmental exposure to ethanol on the vertebrate eye. The purpose of the present study was to determine the gross, microscopic, and ultrastructual effects of developmental exposure to ethanol in the zebrafish model. Eggs were obtained from WT outbred zebrafish and exposed to 0%, 0.1%, 0.2%, 0.4%, 0.5%, or 1.0% (v/v) ethanol to assess viability and the effect of dose and duration of exposure on eye size. Light and electron microscopy were performed on ethanol‐treated and control larvae. Results showed that ethanol treatment decreased viability by about 20% at concentrations of 0.1–0.5% ethanol and by 50% at 1.0% ethanol. Ethanol‐related decreases in eye size were recorded at 6 days postfertilization (dpf) and were dose dependent. There were significant decreases in the volumes of the photoreceptor, inner nuclear, and ganglionic layers and in the lens of 9 dpf ethanol‐exposed compared with control larvae. Ultrastructural examination showed signs of developmental lags in the ethanol‐treated fish as well as abnormal retinal apoptosis in the 6 dpf ethanol‐treated larvae compared with their controls. These results demonstrate that the developing zebrafish eye is sensitive to perturbation with ethanol and displays some of the eye deficits present in fetal alcohol syndrome. J. Comp. Neurol. 502:497–506, 2007. © 2007 Wiley‐Liss, Inc.
Steroidogenic enzymes along the ventricular proliferative zone in the developing songbird brain
Authors: London Sarah E. , Schlinger Barney A. 
Published: March 2007

AbstractNeural development requires regulation and coordination of the differentiation, migration, and survival of newly divided cells, most of which derive from the region surrounding the lateral ventricles. While many factors are involved in these maturational processes, studies of cell proliferation and neurogenesis in songbirds indicate that sex steroids may provide crucial cues to newly divided cells and may be fundamental to the organization of a specific neural circuit, the song system. In the case of the zebra finch, steroids that impact song system masculinization are most likely not synthesized from the gonads but from the brain, and evidence is mounting that both developing and adult zebra finches have the capacity for neurosteroidogenesis. Therefore, we hypothesized that during early development, all of the genes required for de novo sex steroid synthesis would be expressed in regions that would indicate a role for neurosteroids in neural organization. We found that the genes necessary for de novo neurosteroid synthesis at posthatch day 1 (P1) and P5 show a broad expression distribution. Most strikingly, the spatial distribution of expression for all of the genes necessary for androgen synthesis is similar to the previously described pattern of proliferating neuronal precursors along the lateral border of the lateral ventricle. Due to the increasing evidence for neurosteroid action on multiple cell traits, it may be that locally synthesized neurosteroids impact cells along the proliferative zone to influence early events in neural development generally and song system masculinization specifically. J. Comp. Neurol. 502:507–521, 2007. © 2007 Wiley‐Liss, Inc.
Serotonin 5‐HT2A and 5‐HT5A receptors are expressed by different motoneuron populations in rat Onuf's nucleus
Authors: Xu Chen , Giuliano François , Sun X.Q. , Brisorgueil Marie‐Jeanne , Leclerc Patrick , Vergé Daniel , Conrath Marie 
Published: March 2007

AbstractMotoneurons of Onuf's nucleus innervate the pelvic striated muscles, which play a crucial role in erection, ejaculation, and urinary continence. Serotonergic descending projections from the brain are involved in the modulation of Onuf's motoneuron activity. However, conflicting results regarding the effects of spinal serotonin (5‐HT) on pelvi‐perineal functions have been reported. They may be partly accounted for by the multiplicity of neuronal targets and receptor subtypes on which 5‐HT is acting. In order to provide comparative data regarding 5‐HT receptor expression in various groups of Onuf's motoneurons, we used retrograde tracing techniques from different pelvic muscles combined with immunocytochemistry of 5‐HT2A and 5‐HT5A receptors in male and female rats. In males, 5‐HT2A receptor immunolabeling was very dense in motoneurons innervating the ischiocavernosus muscle. By contrast, in female rats, 5‐HT2A receptor expression in Onuf's nucleus was very weak. In both genders, 5‐HT5A receptor immunoreactivity was found in motoneurons innervating the external urethral sphincter. In males, a moderate or low 5‐HT5A immunolabeling was observed in motoneurons innervating the bulbospongiosus and ischiocavernosus muscles, respectively. These data show a preferential localization of 5‐HT2A and 5‐HT5A receptors to motoneurons controlling the striated muscles located at the penile crus and sphincter muscles, respectively, suggesting a specific serotoninergic control on different pelvic functions. In addition, the subcellular distribution of receptors suggests a different mode of action of 5‐HT, paracrine at 5‐HT2A receptors and synaptic at 5‐HT5A receptors. This might have implications for pharmacological research targeting different pelvic functions e.g., micturition and ejaculation. J. Comp. Neurol. 502:620–634, 2007. © 2007 Wiley‐Liss, Inc.
Ultrastructural analysis of aminoglycoside‐induced hair cell death in the zebrafish lateral line reveals an early mitochondrial response
Authors: Owens Kelly N. , Cunningham Dale E. , Macdonald Glen , Rubel Edwin W. , Raible David W. , Pujol Remy 
Published: March 2007

AbstractLoss of the mechanosensory hair cells in the auditory and vestibular organs leads to hearing and balance deficits. To investigate initial, in vivo events in aminoglycoside‐induced hair cell damage, we examined hair cells from the lateral line of the zebrafish, Danio rerio. The mechanosensory lateral line is located externally on the animal and therefore allows direct manipulation and observation of hair cells. Labeling with vital dyes revealed a rapid response of hair cells to the aminoglycoside neomycin. Similarly, ultrastructural analysis revealed structural alteration among hair cells within 15 minutes of neomycin exposure. Animals exposed to a low, 25‐μM concentration of neomycin exhibited hair cells with swollen mitochondria, but little other damage. Animals treated with higher concentrations of neomycin (50–200 μM) had more severe and heterogeneous cellular changes, as well as fewer hair cells. Both necrotic‐like and apoptotic‐like cellular damage were observed. Quantitation of the types of alterations observed indicated that mitochondrial defects appear earlier and more predominantly than other structural alterations. In vivo monitoring demonstrated that mitochondrial potential decreased following neomycin treatment. These results indicate that perturbation of the mitochondrion is an early, central event in aminoglycoside‐induced damage. J. Comp. Neurol. 502:522–543, 2007. © 2007 Wiley‐Liss, Inc.
Expression pattern of Vasohibin during chick development
Authors: Nimmagadda Suresh , Geetha‐Loganathan Poongodi , Pröls Felicitas , Scaal Martin , Christ Bodo , Huang Ruijin 
Published: March 2007

AbstractVasohibin is an angiogenesis inhibitor that is induced in endothelial cells in an autocrine manner. In this study, we cloned a 500‐bp fragment of chick Vasohibin cDNA and analyzed its expression pattern by in situ hybridization during chick development. From HH‐stage 3, expression of Vasohibin is observed in the area opaca and it is expressed throughout the primitive streak during later stages. At HH‐stage 11, Vasohibin is expressed in head paraxial mesoderm, in the vitelline vein, dorsal neural tube, intermediate and lateral plate mesoderm, Wolffian duct, and blood islands at the caudal part of the embryo. In epithelial somites, expression is seen in the region around the somitocoel, and after somite maturation, expression is observed in the myotome, which becomes stronger with development. Expression is detected in fore and hind brain, also in the retina and lens vesicle of the developing eye. In the early limb bud, expression is initiated in the mesenchyme and becomes stronger during later stages. Expression in the limb mesoderm remains strong at the margins but decreases in the central mesenchyme. At day 7, expression is seen in interdigital grooves of the digits and digit‐demarcating regions. During organogenesis, expression is seen in the anlagen of the esophagus, trachea, duodenum, lungs, liver, heart, and gut. Our analysis shows that Vasohibin is expressed in a wide range of tissues and organs suggesting that Vasohibin acts as a physiological regulator of vascular development during chick embryogenesis. Developmental Dynamics 236:1358–1362, 2007. © 2007 Wiley‐Liss, Inc.
A higher order continuum model for the dynamic shear behaviour of multi‐storey frames
Authors: Dündar Cengiz , Mengi Yalçin , Kiral Erhan 
Published: March 2007

AbstractA continuum model is developed to predict the response of multi‐storey frames to dynamic excitations. The equations of the proposed theory are derived in a systematic manner using smoothing operations. The order of the theory is kept arbitrary. To appraise the validity of the theory natural frequencies and vibration shapes predicted by discrete and continuum models are compared. This comparison provides valuable information about goodness of the proposed model because natural frequencies and vibration shapes represent spectral structure of the theory. The most crucial finding obtained from the analysis is that, as an implication of the smoothing operations used in the derivation of the theory, one should define an effective height which is equal to the height of the frame plus half of the height of the top storey. The numerical results indicated that the use of effective height in the analysis improves the prediction of the theory considerably. It is found also that the number of modes the continuum model can describe correctly increases with the number of storeys and that the lowest number of storeys for which the theory can be used is three. Further, it is observed that an increase in the order of the theory improves greatly its prediction and that in the presence of non‐uniform distributions of frame properties, such as, of mass, stiffness, etc., the theory still remains valid.
Dynamic response of multistoreyed brick buildings
Authors: Qamaruddin M. , Arya A. S. , Chandra B. 
Published: March 2007

AbstractThe paper presents the seismic response analysis of a typical multistoreyed brick building. A number of variables representing the physical properties of the structural system, namely, number of storeys from one to four, wall thickness in various storeys from one to one and a half brick thick and damping from 5 per cent to 15 per cent of critical value are considered. A shear beam type multi‐degree‐of‐freedom oscillator is taken to represent these buildings mathematically in which the masses of the floors and walls are assumed as lumped at the floor levels and the floors are assumed as rigid diaphragms. Koyna and El Centro earthquake accelerograms, representing two seismicity levels, are used for computing dynamic response of the buildings. Overturning and torsional effects have been included in the determination of timewise net stresses in the building elements and their seismic capabilities have been examined. From this study the critical sections for providing reinforcing have been identified and the minimum amount of necessary steel has been estimated.
A time varying AR coefficient model for modelling and simulating earthquake ground motion
Authors: Gersch Will , Kitagawa Genshiro 
Published: March 2007

AbstractA smoothness priors‐time varying autoregressive (AR) coefficient model method for the modelling of earthquake ground motion is shown. The method yields the instantaneous smoothed values of the AR coefficients and the instantaneous smoothed values of the innovations variance. These results in turn yield estimates of the instantaneous spectral density, the time varying covariance function and a simulation model for the ground motion data. An example of the application of the method to the analysis of an accelogram from the February 1971 San Fernando, California earthquake is shown.
Short communication block lanczos method for dynamic analysis of structures
Authors: Nour‐Omid Bahram , Clough Ray W. 
Published: March 2007

AbstractThe simple Lanczos method presented in a recent paper by the writers, with application to single vector loads, is extended to include a more general dynamic loading represented as a linear combination of k vectors (load patterns). The result is a set of orthogonal vectors that is used to transform the equations of motion to a banded form, the half‐bandwidth of which becomes k + 1. When k is small relative to the number of equations, this approach provides for a very efficient time‐stepping solution.
Errors in response calculations for beams
Authors: Wada H. , Warburton G. B. 
Published: March 2007

AbstractWhen the finite element method is used to idealize a structure, its dynamic response can be determined from the governing matrix equation by the normal mode method or by one of the many approximate direct integration methods. In either method the approximate data of the finite element idealization are used, but further assumptions are introduced by the direct integration scheme. It is the purpose of this paper to study these errors for a simple structure. The transient flexural vibrations of a uniform cantilever beam, which is subjected to a transverse force at the free end are determined by the Laplace transform method. Comparable responses are obtained for a finite element idealization of the beam, using the normal mode and Newmark average acceleration methods; the errors associated with the approximate methods are studied. If accuracy has priority and the quantity of data is small, the normal mode method is recommended; however, if the quantity of data is large, the Newmark method is useful.
Flexural responses of grouped piles under dynamic loading
Authors: Nogami Toyoaki 
Published: March 2007

AbstractA simple approach to analyse the flexural vibration of grouped piles was developed. In this approach, a pile group is replaced by a single pile for the evaluation of the pile‐head flexibility matrix. Parametric studies were conducted for various conditions of grouped piles. Various features of flexural vibration of pile groups were found. The charts presented in this paper enable quick estimations of dynamic group effects to be made in a manner similar to that widely used for the evaluation of static group effects.
Inelastic analysis of R/C coupled shear walls
Authors: Keshavarzian M. , Schnobrich W. C. 
Published: March 2007

AbstractThis paper presents a method of analysis capable of calculating the response of an R/C coupled shear wall structure subjected to strong earthquake motion without major complications existing in the method itself. The relative simplicity is achieved while retaining reasonable reliability in the computed response. The reliability of the computed results are tested against 1‐ the measured responses of a cantilever column member and a 6‐storey coupled shear wall system under static cyclic lateral loads; and 2‐ the measured responses of two coupled shear wall structures which were subjected to simulated earthquake motions on the University of Illinois Earthquake Simulator. The effects of moment‐axial force interaction in the wall members on the computed overall responses of the coupled shear wall structures and on the behaviour of each individual wall are discussed.
Analysis of the spatial variation of seismic waves and ground movements from smart‐1 array data
Authors: Loh Chin‐Hsiung 
Published: March 2007

AbstractSpecially designed arrays of strong motion seismographs located near earthquake sources are required for engineering studies of the near‐source properties and the spatial variation of seismic waves. The SMART‐1 array in Taiwan provides good records for this type of study. Careful study of the observed strong motion data permits the identification of wave types, directions and apparent wave velocities. In this paper, a principal direction ratio R (f,α) is defined; this indicates the principal direction of the motion (along a nearly straight line) within the range 0 < R < 1. Vertical motion of the ground is also included in this study. Orbit spectrum analysis is used to verify the identification of wave directions and wave types.The spatial variation of seismic waves along the principal direction is studied. From frequency‐domain analysis, mathematical models of the spatial variation of ground displacement are developed using a wave‐number spectrum and the cross‐spectral density function between two spatial coordinates; these models in turn can provide two alternative models for the random vibration analysis of extensive structures subject to multiple point seismic excitation. The SMART‐1 array data gathered during the January 29, 1981 earthquake also are used to demonstrate calculation of the ground strains and differential movements of the array site.From time‐domain analysis, the spatial variation of seismic waves is defined for ground motion along the identified principal direction. The time variation of evolutionary spectra characterized by frequency‐dependent parameters is used for this formulation. The SMART‐1 array data again form the basis for discussion of the spatial variation of model parameters.
Influence of foundation flexibility on soil‐structure interaction
Authors: Riggs H. R. , Waas G. 
Published: March 2007

AbstractThe effect of the base mat flexibility on seismic soil‐structure interaction is studied for an axisymmetric reactor building on a soft and a stiff soil. As a preliminary step, the dynamic response of a massless flexible circular plate with two rigid concentric walls, through which the plate is loaded, is analysed.The response of the plate is found to depend on the plate flexibility, the load distribution and the frequency of excitation. For practical, in‐phase load distributions, the response of the flexible plate is close to that of a rigid plate at low frequencies, but deviates at high frequencies.Including the flexibility of the mat has hardly any effect on the frequencies and damping of the fundamental rocking and vertical modes of the reactor building. This is the case for soft and stiff soil conditions. However, the flexibility of the mat strongly affects the first and higher structural deformation modes. In both cases the amount of energy dissipated in the soil is a significant percentage of the total dissipation, and is essentially unaffected by the mat flexibility.
An evaluation of a class of practical optimization techniques for structural dynamics applications
Authors: Masri S. F. , Werner S. D. 
Published: March 2007

AbstractThis paper evaluates a class of practical optimization techniques for parameter identification of realistic structural dynamic systems. The techniques involve quasi‐Newton methods together with an efficient procedure for estimating complicated error functions. The optimization procedures are verified through their application to several representative examples, including finite‐element models of realistic structural systems. Extensive numerical and graphical results demonstrate the effects of various optimization algorithm parameters on the rate of convergence of the objective function, the parameter vector error norm and the gradient norm. Guidelines are presented as an aid for addressing several significant issues in the practical application of structural dynamics optimization procedures, such as sensitivity problems, uniqueness, initial value definition for the parameter vector, convergence rates, constraints, the effect of alternative cost function definitions, accuracy of alternative gradient evaluation procedures, alternative procedures for estimating the inverse of the Hessian matrix and the use of a quadratic approximation of the objective function.
Dynamic characteristics of soil‐foundation interaction system detected from forced vibration test and earthquake observation
Authors: Ishida Katsuhiko 
Published: March 2007

AbstractThis paper presents some results on the following subjects obtained from in‐situ forced vibration tests and earthquake observations. (1) The characteristics of the radiation damping of soil‐foundation interaction systems vs. non‐dimensional frequency a0 (=ωr/Vs) were experimentally estimated by the equivalent damping ratios hH ( = K′H/2KH) and hR ( = K′R/2KR), which were defined by complex stiffnesses 1KH (= KH + iKH) and 1KR (= KR + iK′R) of soil. The results for hH and hR of base rock were compared with those of soft soil. (2) A comparative study of experimental and theoretical results was made. The theoretical results were obtained from elastic half‐space theory. (3) A semi‐empirical equation to estimate the equivalent S‐wave velocity for the elastic half‐space model is proposed here, considering the effects of layered media. (4) Various comparisons of the results of 1 KH, 1 KR, hH and hR of forced vibration tests and earthquake observations were made.
Seismic shear vibration of embankment dams in semi‐cylindrical valleys
Authors: Dakoulas Panos , Gazetas George 
Published: March 2007

AbstractA rigorous analytical solution is developed for the lateral linear shear response of embankment dams in semi‐cylindrical valleys. Closed‐form algebraic expressions are presented pertaining to both free and base‐induced oscillations, and extensive parametric and comparative studies elucidate the prominent effects of canyon geometry (shape and aspect ratio) on dynamic response. Harmonic steady‐state as well as earthquake‐induced accelerations, displacements and shear strains in the dam are studied and compared with those obtained from 3‐Dimensional analyses for other canyon geometries, as well as from 2‐Dimensional (2‐D) analyses of the dam mid‐section. It is shown that such 2‐D analyses may provide significantly lower values of near‐crest accelerations, but slightly higher values of shear strains and stresses than the 3‐D analyses. The proposed method of analysis is at least three orders of magnitude less expensive than other presently available numerical procedures.
Non‐linear soil–structure interaction analysis based on the boundary‐element method in time domain with application to embedded foundation
Authors: Wolf John P. , Darbre Georges R. 
Published: March 2007

AbstractThe various boundary‐element methods, well established in the frequency domain, are developed in the time domain for a foundation embedded in a layered halfspace. They are the weighted‐residual technique and the indirect boundary‐element method, based on a weighted‐residual equation, and the direct boundary‐element method based on a reciprocity equation, both equations involving time and space. In the indirect approach, formulating the weighted‐residual equation over the last time step only results in the truncated indirect boundary‐element formulation which requires a reduced computational effort. In all cases, convolution integrals occur.The truncated indirect boundary‐element method leads to a highly reliable algorithm, as is verified when a linear analysis in the time domain is compared to the corresponding one in the frequency domain. This boundary‐element formulation, which is non‐local in space and time, represents a rigorous generally applicable method taking into account a layered halfspace in a non‐linear soil‐structure interaction analysis.As an example, the non‐linear soil‐structure interaction analysis of a structure embedded in a halfspace with partial uplift of the basemat and separation of the side wall is investigated.