bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of starburst cholinergic amacrine cells in the retina of Tupaia belangeri
Authors: Knabe Wolfgang , Washausen Stefan , Happel Nicole , Kuhn Hans‐Jürg 
Published: March 2007

Abstract“Starburst” cholinergic amacrines specify the response of direction‐selective ganglion cells to image motion. Here, development of cholinergic amacrines was studied in the tree shrew Tupaia belangeri (Scandentia) by immunohistochemistry with antibodies against choline acetyltransferase (ChAT) and neurofilament proteins. Starburst amacrines expressed ChAT much earlier than previously thought. From embryonic day 34 (E34) onward, orthotopic and displaced subpopulations segregated from a single cluster of immunoreactive precursor cells. Orthotopic starburst amacrines rapidly took up positions in the inner nuclear layer. Displaced starburst amacrines were first arranged in a monocellular row in the inner plexiform layer, and, with a delay of 1 week, they descended to the ganglion cell layer. Conversely, dendritic stratification of displaced amacrines slightly preceded that of orthotopic ones. Starburst amacrines expressed the medium‐molecular‐weight neurofilament protein (NF‐M) from E34 to postnatal day 11 (P11) and coexpressed α‐internexin from E36.5 to P11. Consequently, neurofilaments composed of α‐internexin and NF‐M may stabilize developing dendrites of starburst amacrines. During the first 2 postnatal weeks, subpopulations of anti‐NF‐M‐labeled ganglion cells costratified with the preexisting dendritic strata of starburst amacrines in the ON sublamina, OFF sublamina, or both. Hence, anti‐NF‐M‐labeled ganglion cells may include direction‐selective ones. Thereafter, NF‐M and α‐internexin proteins disappeared from starburst amacrines, and NF‐M immunoreactivity was lost in the dendrites of ganglion cells. Our findings suggest that NF‐M and α‐internexin are important for starburst amacrines and ganglion cells to recognize each other and, thus, contribute to the formation of early developing retinal circuits in the inner plexiform layer. J. Comp. Neurol. 502:584–597, 2007. © 2007 Wiley‐Liss, Inc.
Asymmetric innervation of the habenula in zebrafish
Authors: Hendricks Michael , Jesuthasan Suresh 
Published: March 2007

AbstractThe habenular complex is a paired structure found in the diencephalon of all vertebrates, linking the forebrain and midbrain. Habenulae are asymmetrical and may contribute to lateralized behavior. Recent studies in zebrafish have characterized molecular pathways that give rise to the habenular asymmetry and the distinct projections of the left and right habenula to the midbrain. However, it is unclear whether there are asymmetries in habenula afferents from the forebrain. By lipophilic dye tracing, we find that axons innervating the habenula derive primarily from a region in the lateral diencephalon containing migrated neurons of the eminentia thalami (EmT). EmT neurons terminate in neuropils in both ipsilateral and contralateral habenula. These axons, together with axons from migrated neurons of the posterior tuberculum and pallial neurons, cross the midline via the habenular commissure. Subsets of pallial neurons terminate only in the medial right habenula, regardless of which side of the brain they originate from. These include an unusual type of forebrain projection: axons that cross the midline twice, at both the anterior and habenular commissures. Our data establish that there is asymmetric innervation of the habenula from the telencephalon, suggesting a mechanism by which habenula asymmetry might contribute to lateralized behavior. J. Comp. Neurol. 502:611–619, 2007. © 2007 Wiley‐Liss, Inc.
Elf5 is an epithelium‐specific, fibroblast growth factor–sensitive transcription factor in the embryonic lung
Authors: Metzger David E. , Xu Yan , Shannon John M. 
Published: March 2007

AbstractFibroblast growth factor (FGF) signaling has been shown to be essential for many aspects of normal lung development. To determine epithelial targets of FGF signaling, we cultured embryonic day (E) 11.5 mouse lungs for 24 hr in the presence or absence of the FGF receptor antagonist SU5402, which inhibited branching morphogenesis. Affymetrix gene chip analysis of treated and control epithelia identified several genes regulated by FGF signaling, including Elf5, a member of the Epithelial‐specific Ets family of transcription factors. SU5402 reduced Elf5 expression in mesenchyme‐free cultures of E12.5 epithelium, demonstrating that the inhibition was direct. In situ hybridization revealed that Elf5 had a dynamic pattern of expression during lung development. We found that expression of Elf5 was induced by FGF7 and FGF10, ligands that primarily bind FGFR2b. To further define the pathways by which FGFs activate Elf5 expression, we cultured E11.5 lung tips in the presence of compounds to inhibit FGF receptors (SU5402), PI3‐Kinase/Akt–mediated signaling (LY294002), and MAP Kinase/Erk‐mediated signaling (U0126). We found that SU5402 and LY294002 significantly reduced Elf5 expression, whereas U0126 had no effect. LY294002 also reduced Elf5 expression in cultures of purified epithelium. Finally, pAkt was coexpressed with Elf5 in the proximal epithelial airways of E17.5 lungs. These results demonstrate that Elf5 is an FGF‐sensitive transcription factor in the lung with a dynamic pattern of expression and that FGF regulation of Elf5 by means of FGFR2b occurs through the PI3‐Kinase/Akt pathway. Developmental Dynamics 236:1175–1192, 2007. © 2007 Wiley‐Liss, Inc.
Segmental border is defined by the key transcription factor Mesp2, by means of the suppression of notch activity
Authors: Saga Yumiko 
Published: March 2007

AbstractElaborate somite patterning is based upon dynamic gene regulation within the presomitic mesoderm (PSM), which is derived from the primitive streak and tail bud in the later stage mouse embryo. The Notch signaling pathway and its regulators are major components of most of the events required for temporally and spatially coordinated somite formation. The PSM can be subdivided into at least two domains, based upon transcriptional regulation and gene function. In the posterior PSM, the basic helix–loop–helix (bHLH) protein Hes7 plays a central role in generating a traveling wave of gene expression by negatively regulating the transcription of its target genes. This in turn may define the somite spacing and future segmental units. In the anterior PSM, cells begin to form segmental patterning by acquiring rostral or caudal identities of somite primordia and by defining the segmental border, which must be coupled with the segmentation clock. The link between the clock and segmental border formation is of fundamental importance during somitogenesis. During this process, Mesp2, another basic HLH protein, plays a critical role in the anterior PSM. In this review, I further clarify the dynamic processes leading to segmental border formation in the developing mouse embryo. Developmental Dynamics 236:1450–1455, 2007. © 2007 Wiley‐Liss, Inc.
Synthesis, Structures and Properties of Cluster Complexes [H3O(Ph3PO)3]2[Mo6Cl14] and [H(Ph3PO)2]2[Re6S6Br8]
Authors: Kozhomuratova Zhyldyz S. , Mironov Yuri V. , Shestopalov Michael A. , Drebushchak Irina V. , Moroz Nikolay K. , Naumov Dmitry Y. , Smolentsev Anton I. , Uskov Evgenii M. , Fedorov Vladimir E. 
Published: March 2007

AbstractNew cluster compounds [H3O(Ph3PO)3]2[Mo6Cl14] (I) and [H(Ph3PO)2]2[Re6S6Br8] (II) have been prepared by the reaction of a acetonitrile solution of triphenylphosphane oxide Ph3PO with octahedral cluster complexes of molybdenum (H3O)2Mo6Cl14·6H2O and rhenium K2Re6S6Br8, respectively, (with addition of several drops of HBr). The structures and properties of the products were studied by single‐crystalX‐ray diffraction and NMR and luminescence spectroscopic methods. The compounds studied are characterized by strong hydrogen bonds with O–O distances of 2.45–2.51 Å (I) and 2.34–2.41 Å (II); unusual H‐bonded cationic trimers, [H3O(Ph3PO)3]+, were found in compound I. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Inelastic seismic analysis of a building structure designed by argentine codes
Authors: Sonzogni Victorio E. , Cardona Alberto , Idelsohn Sergio R. 
Published: March 2007

AbstractA reinforced concrete frame‐wall structure of a building designed in accordance to standard practice in Argentina was analysed by the procedures prescribed by current Argentine Codes. In addition, the inelastic step‐by‐step response of the structure to design spectrum‐compatible accelerograms was studied by means of a special element for inelastic dynamic analysis of reinforced concrete frames. Results obtained by the different methods of analysis are presented.
Response of secondary systems in structures subjected to transient excitation
Authors: Hernried Alan G. , Sackman Jerome L. 
Published: March 2007

AbstractAn analytical method, based on matrix perturbation theory, is developed whereby a simple estimate can be obtained of the maximum dynamic response of lightly damped, light equipment (modelled as a n(2)‐degree‐of‐freedom system) attached to a structure (modelled as a n(1)‐degree‐of‐freedom system) subjected to ground motion or impact. A natural frequency of the equipment is considered close or equal to a natural frequency of the structure. It is assumed that the information available to the designer is a time history of the ground motion or impact, or an associated design spectrum; the fixed base modal properties of the structure; and the fixed base modal properties of the equipment. The method employed avoids the direct conventional analysis of a n(2) + n(1)‐degree‐of‐freedom system either by modal or by matrix time‐marching methods; as well as errors in estimates of peak response due to the possible unreliability of numerical schemes because of the lightness of the equipment, or due to uncertainty as to the appropriate procedure for summing the contributions of the two closely spaced modes which occur in the system. The proposed procedure is demonstrated for an example equipment‐structure system. Computed results based on the method are in close agreement with results obtained through a Newmark time‐integration scheme.
Stochastic seismic sliding of rigid mass supported through non‐symmetric friction
Authors: Constantinou Michalakis C. , Gazetas George , Tadjbakhsh Iradj 
Published: March 2007

AbstractThe sliding behaviour of a rigid mass supported on a randomly vibrating foundation through a non‐symmetric Coulomb‐friction contact is studied both analytically and by numerical simulation. The analysis is based on a stationary solution of the associated Fokker‐Planck equation, and makes use of equivalent linearization and of a suitable decomposition of the non‐zero mean non‐stationary sliding process. It is shown that the analytical results yield several exact asymptotic expansions for both small and large values of time. An extensive Monte Carlo type numerical simulation study produces non‐stationary response statistics which are in very good accord with the analytical results. Furthermore, it is found that Gumbel's Extreme Value Distribution reproduces with remarkable accuracy the observed cumulative frequency of maximum slip displacement. The results of this paper may find application in seismic design of embankment dams, earth retaining walls and base ‘isolation’ systems.
Effect of lateral inhomogeneity on seismic waves, II. Observations and analyses
Authors: Ohtsuki Akira , Yamahara Hiroshi , Tazoh Takashi 
Published: March 2007

AbstractObservation has been conducted on soft surface ground with a sloping basement to clarify the effects of lateral inhomogeneity on ground motions and strains induced by seismic waves and to examine the frequency characteristics of the ground surface motions. The scattered Rayleigh wave from the vicinity of the sloping basement has been detected on seismograms and is observed to have a large influence on the ground motions and strains. In this paper the response of the ground is simulated using a hybrid method which combines a particle model and finite element method (FEM). The computed seismograms are in good agreement with observed ones. It is found from the calculations that large ground strains are produced by the scattered Rayleigh waves as well as by the incident shear waves in the surface ground overlying the sloping basement. In addition, the effects of lateral inhomogeneity on an embedded pipeline are examined. The present results are considered to be significant from the viewpoint of earthquake engineering.
A numerical model for seismic analysis of masonry buildings: Experimental correlations
Authors: Benedetti D. , Benzoni G. M. 
Published: March 2007

AbstractA non‐linear finite element model for plain masonry structures under lateral static loads and seismic base inputs is presented. Three super‐imposed elasto‐plastic shear elements are used in order to approximate the typical force‐displacement curve for masonry. Material properties are identified with respect to results of shear tests on single piers. Modelling of entire structures is then performed and the numerical results are satisfactorily checked against the experimental outputs of static and shaking table tests of simple 1 and 2 storey buildings. The out of plane behaviour of walls is accounted for by means of a simplified method.
Vibration of continuous skew plates
Authors: Mizusawa T. , Kajita T. 
Published: March 2007

AbstractThis note presents vibration analysis of continuous skew plates with intermediate supports by the Rayleigh‐Ritz method with B‐spline functions.The accuracy of the present method is shown in a few typical cases. The results are compared with existing results based on other numerical methods and found to be in good agreement.Natural frequencies of continuous skew plates with several elastic point supports are also analysed for different skew angles and for different stiffnesses of point supports.
Dynamic slope stability analyses with a non‐linear finite element method
Authors: Toki Kenzo , Miura Fusanori , Oguni Yoshiyuki 
Published: March 2007

AbstractA new technique is presented with which to investigate slope stability during strong earthquake motion. This technique is based on a non‐linear finite element method that uses a joint element to express non‐linear behaviour and the progressive failure of a slope. Joint elements are arranged at every interface between soil elements. Accordingly, each soil element is allowed to move in directions parallel, perpendicular and rotational to neighbouring elements; consequently, they express the sliding and separation at any interface between the soil elements.The method was used to investigate the stability of an existing slope during strong earthquake motions. Preliminary static analyses were made, and their results were compared with results obtained with Janbu's method in order to check the validity of our proposed method.The dynamic analyses also took into account the material non‐linearity of the soil. The process of progressive failure was examined for a slope whose material constants are known. The influence of input excitations on slope stability is discussed in detail. The method also has been used to assess the effectiveness of a countermeasure used to prevent slope failure.
Displacement solutions for dynamic loads in transversely‐isotropic stratified media
Authors: Waas G. , Riggs H. R. , Werkle H. 
Published: March 2007

AbstractSolutions for the displacements caused by dynamic loads in a viscoelastic transversely‐isotropic medium are derived. The medium extends horizontally to infinity, but is bounded below by a rigid base. Stratification of the medium presents no difficulties. The medium is discretized in the vertical direction only; discretization in the horizontal direction is obviated by use of analytical solutions to the equations of motion.Application of the displacement solutions to soil‐structure interaction is illustrated. A soil flexibility matrix (and hence, a stiffness matrix) for a surface foundation follows directly from the displacement solutions. A simple modification to obtain the soil stiffness for an embedded foundation of arbitrary geometry is described. Stiffnesses of rigid surface and embedded foundations are computed and compared with previously published results. In addition, the dynamic stiffness of a rigid surface foundation on a soil layer with linearly increasing shear modulus is compared to that for a homogeneous soil layer. A reduction in radiation damping is found to result from the inhomogeneity.
Non‐linear soil‐structure‐interaction analysis using green's function of soil in the time domain
Authors: Wolf John P. , Obernhuber Pius 
Published: March 2007

AbstractThe contribution of the (linear) unbounded soil to the basic equation of motion of a non‐linear analysis of soil‐structure interaction consists of convolution integrals of the displacement‐force relationship in the time domain and the history of the interaction forces. The former is calculated using the indirect boundary‐element method, which is based on a weighted‐residual technique and involves Green's functions.As an example of a non‐linear soil‐structure‐interaction analysis, the partial uplift of the basemat of a structure is examined.As the convolution integrals have to be recalculated for each time step, the computational effort in this rigorous procedure is substantial. A reduction can be achieved by simplifying the Green's function by ‘concentrating’ the region of influence. Alternatively, assuming a specified wave pattern, a coupled system of springs and dashpots with frequency‐independent coefficients can be used as an approximation.
Attenuation characteristics of peak horizontal acceleration in Northeast and Southwest China
Authors: Peng Ke‐Zhong , Wu F. T. , Song Liangyu 
Published: March 2007

AbstractRegional seismic characteristics in northeastern and southwestern China are quite different. Earthquakes are more frequent in SW China than in NE China and intensity attenuates faster in SW China than in NE China. Through regression analyses of data from these two regions we have found the attenuation of peak horizontal accelerations also to be noticeably different. For northeastern China the regression is log10(a) = −0.474 + 0.613M − 0.873 log10 (R) −0.00206R and for southwestern China, the regression is log10 (a) = 0.437 + 0.454M − 0.739 log10 (R) −0.00279R where a is acceleration in cm/sec2, M is the Chinese surface wave magnitude (Institute of Geophysics, State Seismological Bureau), and R is the distance in kilometres. The formula for northeastern China has distance coefficients similar to those for Central United States as derived by Nuttli and Herrmann14.
Dynamic analysis of prismatic structures surrounded by an infinite fluid medium
Authors: Cheung Y. K. , Zhi‐Yuan Cao , Wu S. Y. 
Published: March 2007

AbstractFor coupled vibration analyses of prismatic shell structures immersed in an infinite fluid medium, a composite element consisting of a semi‐analytical infinite fluid element and a cylindrical shell strip element is proposed in this paper. The behaviour in the infinite direction can be accurately modelled with minimum effort and great saving in computational cost is achieved using this element. Unlike many other methods which tend to take advantage of axisymmetry to simplify the analysis, this method may be used to analyse the dynamic behaviour of prismatic shell structures with arbitrary cross‐sections in offshore engineering.
On the natural frequencies of infilled frames
Authors: Thiruvengadam V. 
Published: March 2007

AbstractThree approximate models are considered for the evaluation of the first few natural frequencies and associated mode shapes of infilled frames, a commonly occurring composite structural system formed by the combination of plane frames and filler walls. The reasonableness of the models is checked with the available experimental results and with the corresponding finite element solutions. The multiple strut model, wherein the infills are replaced by a set of equivalent multiple struts, can account for the frame–infill separation and infill openings and this model is seen to be an improvement over the single equivalent diagonal strut models proposed by earlier investigators. The shear—flexure cantilever analogy, by rationally evaluating the fundamental frequency, aids the equivalent lateral load procedures of the earthquake analysis. For dealing with the frames with central infill openings an equivalent plane frame model is discussed.Besides presenting the approximate models, the effect of frame—infill separation in reducing the fundamental frequency is investigated and an empirical relation is presented in this regard. Also some of the factors influencing the frame—infill contact lengths are studied and this indicates that the contact lengths are highly sensitive and indeterminate. Some constructional methods for avoiding separation and ensuring effective composite action between the frame and infill are also suggested.
Dynamic behaviour of CLASP‐type buildings
Authors: Dumanoglu A. A. , Severn R. T. 
Published: March 2007

AbstractThis paper deals with the dynamic behaviour of pin‐jointed, steel‐framed buildings which derive stiffness from bracing and cladding, and their response to earthquake loading.The first part of the paper considers the best way to obtain an analytical model, using the natural frequencies and mode‐shapes measured on a CLASP building in Nottingham employing eccentric‐mass vibrators. The second part is a study of a key section of a CLASP hospital now under construction in Algeria, in which the earthquake‐induced forces in the bracing are calculated. The final part is concerned with studies on two‐storey and three‐storey CLASP‐type models, using different bracing arrangements.
Elasto‐plastic earthquake shear‐response of one‐dimensional earth dam models
Authors: Elgamal Ahmed‐W. M. , Abdel‐Ghaffar Ahmed M. , Prevost Jean H. 
Published: March 2007

AbstractA simplified analysis procedure for the non‐linear hysteretic earthquake‐response of earth dams is presented. The dam is modelled as a one‐dimensional hysteretic shear‐wedge subjected to base excitation. The hysteretic stress‐strain behaviour of the dam materials is modelled by using elasto‐plastic constitutive equations based on multi‐surface kinematic plasticity theory. The method is based on a Galerkin formulation of the equations of motion in which the solution is expanded using eigenmodes of the linearized problem defined over the spatial domain occupied by the dam. The technique is applied to analyse the non‐linear dynamic response of an earth dam subject to two very different input ground motions. The following investigations are presented: (i) comparison between the results obtained using two soil models depicting different nonlinear properties, (ii) comparison between the results of the one‐mode and the multi‐mode solution expansions, (iii) comparison with the results obtained through an elaborate finite element representation of the dam, and finally, (iv) comparison with the results obtained through the Makdisi‐Seed11 iterative procedure for earth dam analysis. The comparisons show that the proposed technique can be used to determine adequately the transient earthquake response of long earth dams. Furthermore, the efficiency and low computational cost make the technique very attractive; it can easily and systematically be extended to two‐ and three‐dimensional calculations of earth dam response.