bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of secondary systems in structures subjected to transient excitation
Authors: Hernried Alan G. , Sackman Jerome L.
Published: March 2007

An 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

The 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

Observation 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

A 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

This 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

A 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

Solutions 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

The 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

Regional 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

For 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

Three 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

This 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

A 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.
Generation of floor response spectra including oscillator‐structure interaction
Authors: Igusa Takeru , Kiureghian Armen Der
Published: March 2007

A method is presented for generating floor response spectra for aseismic design of equipment attached to primary structures. The method accurately accounts for tuning, interaction and non‐classical damping, which are inherent characteristics of composite oscillator‐structure systems. Modal synthesis and perturbation techniques are used to derive the modal properties of the composite system in terms of the known properties of the structure and the oscillator. Floor spectra are generated directly in terms of these derived properties and the input ground response spectrum using modal combination rules that account for modal correlations and non‐classical damping. The computed spectra, in general, are considerably lower than conventional floor response spectra due to the effect of interaction. They provide more realistic and economical criteria for design of equipment. The method is accurate to the order of perturbation and is computationally efficient, as it avoids time‐history analysis and does not require numerical eigenvalue evaluation of the composite oscillator‐structure system. The results of a parametric study demonstrate the accuracy of the method and illustrate several key features of floor response spectra.
A study of railway bridge/vehicle interaction and evaluation of fatigue life
Authors: Garg V. K. , Chu K. H. , Wang T. L.
Published: March 2007

A new vehicle model and the partial bridge model were used to study the dynamic interaction between an open deck steel truss bridge and a moving freight train. The responses in terms of dynamic stresses in certain critical members in the bridge were generated to predict their fatigue lives by using a reliability‐based methodology.
A hybrid method for three‐dimensional problems of dynamics of foundations
Authors: Lin Hong‐Tsung , Tassoulas John L.
Published: March 2007

A method is developed applicable to problems of dynamics of arbitrary‐geometry foundations. Finite elements are employed in the near field in order to obtain a discrete solution. In the far field, a semidiscrete solution is synthesized from modes also calculated by the finite element method. The solutions are matched by applying the stationarity condition of a functional. Examples of application are presented in order to verify the validity and illustrate the use of the method.
Modal time history analysis of non‐classically damped structures for seismic motions
Authors: Singh M. P. , Ghafory‐Ashtiany M.
Published: March 2007

The step‐by‐step modal time history integration methods are developed for dynamic analysis of non‐classically damped linear structures subjected to earthquake‐induced ground motions. Both the mode displacement and mode acceleration‐based algorithms are presented for the calculation of member and acceleration responses. The complex‐valued eigenvectors are used to effect the modal decoupling of the equations of motion. However, the recursive step‐by‐step algorithms are still in terms of real quantities. The numerical results for the acceleration response and floor response spectra, obtained with these approaches, are presented. The mode acceleration approach is observed to be decidedly better than the mode displacement approach in as much as it alleviates the so‐called missing mass effect, caused by the truncation of modes, very effectively. The utilization of the mode acceleration‐based algorithms is, thus, recommended in all dynamic analyses for earthquake‐induced ground motions.
Uplift in seismic response of pile supported buildings
Authors: El Hifnawy L. , Novak M.
Published: March 2007

To resist seismic overturning moments piles are often designed for tensile forces which require pile connection to the cap and sometimes, socketing. For typical buildings, this paper theoretically examines the effect of these measures on seismic response, forces and pile loading in dependence on pile numbers, configuration and tip conditions.
A comparison of time‐domain transmitting boundaries
Authors: Wolf John P.
Published: March 2007

A non‐linear interaction analysis with a (generalized) non‐linear structure and a linear unbounded soil is analysed in the time domain, based either on the sub‐structure method, which involves global convolution integrals, or on the direct method with local boundary conditions. Alternatively, the hybrid frequency–time‐domain method of analysis, which is an iterative scheme, could be used. Approximate local boundary conditions to model the wave propagation towards infinity on the artificial boundary used in the direct method of non‐linear soil–structure‐interaction analysis to be performed in the time domain are examined. A semi‐infinite rod supported elastically, which exhibits the same properties as certain unbounded soils such as dispersion and a cut‐off frequency, is used for the investigation. For a transient excitation, the superposition boundary with frequent averaging, the well‐known viscous damper and the extrapolation algorithm lead to good accuracy. Moving the artificial boundary further away from the structure (or more precisely, increasing the ratio of the distance of the artificial boundary to the wave length) improves the accuracy.
Wind erosion and intensive prehistoric agriculture: A case study from the Kalaupapa field system, Moloka'i Island, Hawai'i
Authors: McCoy Mark D. , Hartshorn Anthony S.
Published: March 2007

Wind erosion is a major problem for modern farmers, a key variable affecting nutrient levels in ecosystems, and a potentially major force impacting archaeological site formation; however, it has received scant consideration in geoarchaeological studies of agricultural development compared with more easily quantifiable environmental costs, such as vegetation change or fluvial erosion. In this study, soil nutrient analysis is used in the Kalaupapa field system, Moloka'i Island, Hawai'i, to detect an increase in wind erosion attributable to intensive agriculture following the burning of endemic forest. This practice began on a small scale in the 13th century A.D., expanded around cal A.D. 1450–1550, and continued until the near total abandonment of the fields after European contact in the 18th century. Nutrients that naturally occur in high amounts in coastal windward areas due to the long‐term, cumulative effect of sea spray were especially impacted. However, thanks to the unique landform of the Kalaupapa Peninsula, nutrient depletion in windward areas was offset by downwind enrichment and likely contributed to the long‐term sustainability of the system as a whole. Future research on tropical and arid agriculture should consider the cumulative environmental cost of increased eolian erosion attributable to anthropogenic landscape modification. © 2007 Wiley Periodicals, Inc.
Cutaneous phenotype and MC1R variants as modifying factors for the development of melanoma in CDKN2A G101W mutation carriers from 4 countries
Authors: Goldstein Alisa M. , Chaudru Valerie , Ghiorzo Paola , Badenas Celia , Malvehy Josep , Pastorino Lorenza , Laud Karine , Hulley Benjamin , Avril Marie‐Francoise , Puig‐Butille Joan A. , Miniere Annie , Marti Rosa , Chompret Agnes , Cuellar Francisco , Kolm Isabel , Mila Montserrat , Tucker Margaret A. , Demenais Florence , Bianchi‐Scarra Giovanna , Puig Susana , de‐Paillerets Brigitte Bressac
Published: March 2007

The G101W founder mutation is the most common CDKN2A mutation in Italy, Spain, and France. As the background of modifying genes, environmental exposures, and sun behavior vary across countries, studying G101W carriers from distinct countries offers a unique opportunity to evaluate possible modifying factors in melanoma development. We evaluated 76 G101W cases and 59 carrier controls from France, Italy, Spain, and the United States. Hair color and dysplastic nevi distributions differed significantly in cases and controls across the 4 study groups. Cases also varied significantly for eye color, freckling, and nevi. The distribution of MC1R variants in cases differed significantly across study groups because 12% of Italian melanoma patients had ≥2 MC1R variants vs. >50% for the other case groups. Several MC1R covariates showed significant associations with melanoma risk in all groups combined and in the American, French, and Spanish samples; no significant findings were observed in the Italian sample. In multiple‐case families, the number and type of MC1R variants varied significantly between multiple‐primary‐melanoma and single‐primary‐melanoma patients from the 4 groups; there was also a significant decrease in median age at melanoma diagnosis as the number or type of MC1R variants increased. The variation in the effects of the cutaneous phenotypic and MC1R factors across the study sample suggests that these factors differentially contribute to development of melanoma even on a common genetic background of a germline CDKN2A mutation. Differences in melanoma risk across geographic regions justify the need for individual studies in each country before counseling should be considered. © 2007 Wiley‐Liss, Inc.
Option prices, exchange market intervention, and the higher moment expectations channel: a user's guide
Authors: Galati Gabriele , Higgins Patrick , Humpage Owen , Melick William
Published: March 2007

A vast literature on the effects of sterilized intervention by the monetary authorities in the foreign exchange markets concludes that intervention systematically moves the spot exchange rate only if it is publicly announced, coordinated across countries, and consistent with the underlying stance of fiscal and monetary policy. Over the past 15 years, researchers have also attempted to determine if intervention has any effects on the dispersion and directionality of market views concerning the future exchange rate. These studies usually focus on the variance around the expected future exchange rate—the second moment. In this paper we demonstrate how to use over‐the‐counter option prices to recover the risk‐neutral probability density function (PDF) for the future exchange rate. Using the yen/dollar exchange rate as an example, we calculate measures of dispersion and directionality, such as variance and skewness, from estimated PDFs to test whether intervention by the Japanese Ministry of Finance during the period 1996–2004 had any impact on the higher moments of the exchange rate. We find little or no systematic effect, consistent with the findings of the literature on the spot rate as: Japanese intervention was not publicly announced prior to August 2000, and since that time only publicly announced after the fact, over the past 10 years rarely coordinated across countries and, in hindsight, probably inconsistent with the underlying stance of monetary policy. Copyright © 2007 John Wiley & Sons, Ltd.
Guidelines on the use of therapeutic apheresis in clinical practice—Evidence‐based approach from the apheresis applications committee of the American society for apheresis
Authors: Szczepiorkowski Zbigniew M. , Bandarenko Nicholas , Kim Haewon C. , Linenberger Michael L. , Marques Marisa B. , Sarode Ravindra , Schwartz Joseph , Shaz Beth H. , Weinstein Robert , Wirk Ashka , Winters Jeffrey L.
Published: March 2007

The American Society for Apheresis (ASFA) Apheresis Applications Committee is charged with a review and categorization of indications for therapeutic apheresis. This elaborate process had been undertaken every 7 years resulting in three prior publications in 1986, 1993, and 2000 of “The ASFA Special Issues.” This article is the integral part of the Fourth ASFA Special Issue. The Fourth ASFA Special Issue is significantly modified in comparison to the previous editions. A new concept of a fact sheet has been introduced. The fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis. A detailed description of the fact sheet is provided. The article consists of 53 fact sheets devoted to each disease entity currently categorized by the ASFA. Categories I, II, and III are defined as previously in the Third Special Issue. However, a few new therapeutic apheresis modalities, not yet approved in the United States or are currently in clinical trials, have been assigned category P (pending) by the ASFA Clinical Categories Subcommittee. The diseases assigned to category IV are discussed in a separate article in this issue. J. Clin. Apheresis., 2007 © 2007 Wiley‐Liss, Inc.
Iso‐guanine quintet complexes coordinated by mono valent cations (Na+, K+, Rb+, and Cs+)
Authors: Gu Jiande , Wang Jing , Leszczynski Jerzy
Published: March 2007

The geometric structures, the interaction energies, the vibrational characteristics, and the electronic structures of the complexes of the isoguanine (isoG) quintet coordinated with mono valent cations (Na+, K+, Rb+, and Cs+) have been studied based on the nonplanar models. The geometry of the local minimum structure of the Na+‐isoG quintet complex deviates significantly from the planar structure. The geometric characteristics of the Na+‐isoG quintet complex support the experimental findings that Na+ is unlikely to induce the formation of the isoG quintet‐based pentaplexes. Similar to the guanine tetraplexes, the ionic selectivity of the isoG quintet‐based pentaplexes is largely dominated by the hydration energy of the cations. After hydration correction, the positive value of the free energy difference for the formation of the Na+‐isoG quintet complex (ΔGf) suggests that the isoG quintet is unable to capture the hydrated Na+. The negative values of ΔGf for the K+ and Rb+ complexes implies that both ions have the tendency to be inserted into the isoG pentaplexes. This study suggests that, to elucidate the high Cs+ selectivity of isoG pentaplexes, it is necessary to extend the model from the isoG quintet to the isoG decamer. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007.
Analysis of the interfacial micromorphology of adhesive systems in cavities prepared with Er,Cr:YSGG, Er:YAG laser and bur
Authors: Aranha Ana Cecilia Correa , Eduardo Carlos De Paula , Gutknecht Norbert , Marques Marcia Martins , Ramalho Karen Müller , Apel Christian
Published: March 2007

The purpose of this in vitro study was to evaluate the interaction pattern of adhesive systems on laser and bur cavities. Cavities were prepared according to the following groups (n = 9): (G1) conventional diamond bur (No. 1013); (G2) Er:YAG laser (250 mJ, 4 Hz, 80.6 J/cm2); (G3) Er,Cr:YSGG laser (3.5 W, 20 Hz, 61.7 J/cm2). After cavity preparation, specimens were divided into three subgroups differing the adhesive systems used (n = 3): (GA) AdheSE; (GB) Clearfil standard error (SE) Bond; (GC) Single Bond. After insertion of a micro‐hybrid composite resin, the specimens were sectioned across the bonded surface dividing the teeth into two halves, which were prepared for SEM analysis. Cavities prepared with laser appeared to be more irregular than the bur cavities. Different patterns of gap formation and resin tags could be observed, showing the differences, advantages, and disadvantages of both types of cavities. Under the settings of the present study, resin tags were more pronounced in lased dentin than bur prepared dentin independently of the bonding systems used. On the other hand gap formation between dentin and resin in laser prepared cavities was observed suggesting collagen alteration. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Diversity of the vomeronasal system in mammals: The singularities of the sheep model
Authors: Salazar Ignacio , Quinteiro Pablo Sanchez , Alemañ Nuria , Cifuentes Jose Manuel , Troconiz Patricia Fernandez
Published: March 2007

The enormous morphological diversity and heterogeneity of the vomeronasal system (VNS) in mammals ‐as well as its complete absence in some cases‐ complicates the extrapolation of data from one species to another, making any physiological and functional conclusions valid for the whole Mammalian Class difficult and risky to draw. Some highly‐evolved macrosmatic mammals, like sheep, have been previously used in interesting behavioral studies concerning the main and accessory olfactory systems. However, in this species, certain crucial morphological peculiarities have not until now been considered. Following histological, histochemical and immunohistochemical procedures, we have studied the vomeronasal organ (VNO) and the accessory olfactory bulb (AOB) of adult sheep. We have determined: (1) that all structures which classically define the VNO in mammals are present and well developed, providing the morphological basis for functional activity. (2) that, conversely, there is only a scant population of scattered mitral/tufted cells. One morphological consequence of both details is that the strata of the AOB in adult sheep are not as sharply defined as in other species; moreover, the small number of the mitral/tufted cells in the AOB may imply that the VNS of adult sheep is not capable of functioning in the way a well‐developed VNS does in other species. (3) the zone to zone projection from the apical and basal sensory epithelium of the VNO to the anterior and posterior part of the AOB, respectively, typical in rodents, lagomorphs and marsupials, is not present in adult sheep. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Overexpression of 14‐3‐3γ causes polyploidization in H322 lung cancer cells
Authors: Qi Wenqing , Liu Xiaobing , Chen Weiming , Li Qiang , Martinez Jesse D.
Published: March 2007

The 14‐3‐3 proteins are a family of highly conserved proteins that participate in a wide variety of cellular processes. Mounting evidence suggests that 14‐3‐3 proteins have a role in human cancers, however their role in tumorigenesis is unclear. Here we report that over‐expression of 14‐3‐3 γ protein in human lung cancer cell line H322 results in abnormal DNA replication and polyploidization. Cells that overexpress 14‐3‐3 γ are resistant to microtubule inhibitors and can reenter the cell cycle in the absence of mitosis suggesting that elevated levels of 14‐3‐3 γ may enable cells to bypass the mitotic checkpoint. Taken together, our data indicate that 14‐3‐3γ may contribute to tumorigenesis by promoting genomic instability. © 2007 Wiley‐Liss, Inc.
Depression rating scales in Parkinson's disease: Critique and recommendations
Authors: Schrag Anette , Barone Paolo , Brown Richard G. , Leentjens Albert F.G. , McDonald William M. , Starkstein Sergio , Weintraub Daniel , Poewe Werner , Rascol Olivier , Sampaio Cristina , Stebbins Glenn T. , Goetz Christopher G.
Published: March 2007

Depression is a common comorbid condition in Parkinson's disease (PD) and a major contributor to poor quality of life and disability. However, depression can be difficult to assess in patients with PD due to overlapping symptoms and difficulties in the assessment of depression in cognitively impaired patients. As several rating scales have been used to assess depression in PD (dPD), the Movement Disorder Society commissioned a task force to assess their clinimetric properties and make clinical recommendations regarding their use. A systematic literature review was conducted to explore the use of depression scales in PD and determine which scales should be selected for this review. The scales reviewed were the Beck Depression Inventory (BDI), Hamilton Depression Scale (Ham‐D), Hospital Anxiety and Depression Scale (HADS), Zung Self‐Rating Depression Scale (SDS), Geriatric Depression Scale (GDS), Montgomery‐Asberg Depression Rating Scale (MADRS), Unified Parkinson's Disease Rating Scale (UPDRS) Part I, Cornell Scale for the Assessment of Depression in Dementia (CSDD), and the Center for Epidemiologic Studies Depression Scale (CES‐D). Seven clinical researchers with clinical and research experience in the assessment of dPD were assigned to review the scales using a structured format. The most appropriate scale is dependent on the clinical or research goal. However, observer‐rated scales are preferred if the study or clinical situation permits. For screening purposes, the HAM‐D, BDI, HADS, MADRS, and GDS are valid in dPD. The CES‐D and CSDD are alternative instruments that need validation in dPD. For measurement of severity of depressive symptoms, the Ham‐D, MADRS, BDI, and SDS scales are recommended. Further studies are needed to validate the CSDD, which could be particularly useful for the assessment of severity of dPD in patients with comorbid dementia. To account for overlapping motor and nonmotor symptoms of depression, adjusted instrument cutoff scores may be needed for dPD, and scales to assess severity of motor symptoms (e.g., UPDRS) should also be included to help adjust for confounding factors. The HADS and the GDS include limited motor symptom assessment and may, therefore, be most useful in rating depression severity across a range of PD severity; however, these scales appear insensitive in severe depression. The complex and time‐consuming task of developing a new scale to measure depression specifically for patients with PD is currently not warranted. © 2007 Movement Disorder Society
Ein schiefes Randwertproblem zu einer elliptischen Differentialgleichung zweiter Ordnung mit einer expliziten L2‐Abschätzung für die zweiten Ableitungen der Lösung
Authors: Witsch K. J. , Leis R.
Published: March 2007

In connection with the free boundary value problem of determining the earth's surface from measurements of gravitational potential and force‐field (“the geodetic boundary problem”), an oblique derivative problem

equation image

arises, where D0 is some bounded domain, star shaped with respect to the origin. In order to prove a uniquencess theorem for the geodetic boundary problem, it is essential to give estimates for (weighted) L2‐norms of the second derivatives of the solutions so that their bounds can be estimated numerically if bounds for the function describing the boundary are known. In this paper a Fredholm inverse for the above problem is constructed and the second derivatives of the solutions are estimated in the desired form.
Asymptotic expansions for central limit theorems for general linear stochastic processes. II: Models of the general random noise and pulse train processes
Authors: Butzer P. L. , Gather U. , Törnig W.
Published: March 2007

This part is concerned with the applications of the theorems on error estimates for asymptotic expansions in the central limit theorem for general linear stochastic processes of Part I to two important typical models. These are the general random noise process and a class of pulse train processes that occur in stochastic signal theory and in a variety of digital communication schemes. The assumptions on the inherent structure of the general theorems turn out to be simple here.
The direction of the secondary wave motion in the Ekman boundary layer
Authors: True H. , Kirchgässner K.
Published: March 2007

The secondary wave motion in the free Ekman layer, on which a constant shear stress acts, is examined by an analytic method. The results show, that the waves move away from the center of rotation.
Generalized Hopf bifurcation in Hilbert space
Authors: Kielhöfer H. , Kirchgässner K.
Published: March 2007

We consider a family of semilinear evolution equations in Hilbert space of the form

equation image

with, in general, unbounded operators *A(λ), F(λ·) depending analytically on a real parameter λ. We assume that the origin is a stationary solution, i.e. F(λ,0) = 0, for all λ ε R and that the linearization (with respect to u) at the origin is given by du/dt + A(λ)u = 0. Our essential assumption is the following:
A(λ) possesses one pair of simple complex conjugate eigenvalues μ(λ) = Re μ(λ) ± i Im μ(λ) such that Im μ(0) > 0 and

equation image

for some m ε N or

equation image

If m = 1 the curves of eigenvalues μ(λ) cross the imaginary axis transversally at ±i Im μ(0). In this case a unique branch of periodic solutions emanates from the origin at λ = 0 which is commonly called Hopf bifurcation. If μ(λ) and the imaginary axis are no longer transversal, i.e. m > 1, we call a bifurcation of periodic solutions, if it occurs, a generalized Hopf bifurcation. It is remarkable that up to m such branches may exist. Our approach gives the number of bifurcating solutions, their direction of bifurcation, and its asymptotic expansion. We regain the results of D. Flockerzi who established them in a completely different way for ordinary differential equations.
Constructive existence theorems for problems of Thomas‐Fermi Type
Authors: Mooney J. W. , Roach G. F.
Published: March 2007

A minimal positive solution of the Thomas‐Fermi problem ẅ = λt−1/2 w3/2, w(0) = 1, w(1) = w(1) is shown to exist for each λ > 0. It is proved that all positive solutions, for a given value of λ, are strictly ordered and that the minimal positive solution wλ is a decreasing function of λ. Upper and lower analytic bounds for wλ are given and these bounds are shown to initiate sequences of Picard and Newton iterates which converge monotonically to wλ. A comparative analysis of the efficiency of the iteration schemes is presented. The methods used are of a general nature and can be applied to a variety of nonlinear boundary value problems of convex type [14].
On minimal nonlinearities which permit bifurcation from the continuous spectrum
Authors: Küpper T. , Roach G. F.
Published: March 2007

Bifurcation from the continuous spectrum of a linearized operator is of interest in many physical problems. For example it occurs in the nonlinear Klein‐Gordon equation and in nonlinear integrodifferential equations as the Choquard problem; it further appears in nonlinear integral equations of the convolution type.

A general theory enclosing all these problems is not yet known. To understand the basic phenomena, we therefore consider monotone differential operators whose linearisations have a purely continuous spectrum. It is shown that in fact the lowest point of the continuous spectrum is a bifurcation point, if the nonlinearity grows sufficiently strong.
A finite element method for the solution of a potential theory integral equation
Authors: Friedman M. J. , Nedelec J. C.
Published: March 2007

This paper discusses a finite element approximation for an integral equation of the second kind deduced from a potential theory boundary value problem in two variables. The equation is shown to admit a unique solution, to be variational and coercive in the Hilbert space of functions σ ε H1/2(Γ), frd γ = 0. The Galerkin method with finite elements as trial functions is shown to lead to an optimal rate of convergence.
Zwei Klassen vollständiger Funktionensysteme zur Behandlung der Randwertaufgaben der Schwingungsgleichung ΔU + k2U = 0
Authors: Müller C. , Kersten H. , Leis R.
Published: March 2007

In this paper we present new methods to solve the classical Dirichlet and Neumann problems for ΔU + k2U = 0. We prove that the solutions of this equation for a region S containing G restricted to G are dense in L2(∂G). Introducing a basis in the space of solutions for S we find a complete orthogonal system in L2(∂G) which can be used to solve the boundary value problems by means of approximation in the Hilbertspace norm. Regularity estimates lead to series expansions in G.

The well‐known basis systems obtained by separation of variables thus may be used for every regular region without the very special geometric restrictions. Another class of basis systems may be obtained in analogy to the Runge. theorems by considering types of singularity functions.
A singular perturbation approach for a reaction diffusion system arising in nuclear reactor theory
Authors: de Mottoni P. , Tesei A. , Eckhaus W.
Published: March 2007

The qualitative behavior of the solutions of a reaction‐diffusion system arising in the theory of nuclear reactors is investigated by means of singular perturbation techniques, the small parameter ϵ representing the inverse of neutron velocity. At the lowest approximation for small ϵ the solutions exhibit oscillations about the unique strictly positive equilibrium, much as in the case of the associated lumped parameter system. A two‐times representation for solutions of small amplitudes is also given.
Uniform convergence of the horizontal line method for solutions and free boundaries in Stefan evolution inequalities
Authors: Jerome J. W. , Brosowski B.
Published: March 2007

The change of variable for the temperature Θ in the one‐phase Stefan problem leads to the evolution inequality, (ut – Δu – f)(v – u) ⩾ 0 for all regular v ⩾ 0, where u ⩾ 0 is required. This inequality is to hold over a space‐time domain D = Ω × (0, T) with a Dirichlet boundary condition imposed on ∂ Ω × (0, T) and a zero initial condition. The free boundary phase interface is given in one space dimension by

The fully implicit divided difference scheme

leads to a sequence of elliptic variational inequalities for {um}. The sequence {um} may be interpolated linearly in t to obtain an approximation UΔt of u. The following results are obtained in this paper: (i) a two‐sided weak maximum principle for um – um‐1 in N space dimensions, hence the free boundary approximation for N = 1,

is a monotone increasing step function; (ii) the uniform convergence of UΔt and ∇UΔt, to u and ∇u, respectively, on D; (iii) the uniform convergence to the Hölder continuous, monotone increasing free boundary x on [0, T] of the piecewise linear sequence xΔt, where xΔt interpolates xΔt, in one space dimension; (iv) a constructive existence proof for u and x in prescribed regularity classes.
On uniqueness of Neumann‐Tricomi problem in R2
Authors: Aziz A. K. , Schneider M. , Gilbert R. P.
Published: March 2007

We consider the equation of mixed type

equation image

(k(y) ⪌ 0 whenever y ⪌ 0) in a region G which is bounded by the curves: A piecewise smooth curve Γ lying in the half‐plane y > 0 which intersects the line y = 0 at the points A(‐1, 0) and B(0, 0). For y < 0 by a piecewise smooth curve Γ through A which meets the characteristic of (1) issued from B at the point P and the curve Γ which consists of the portion PB of the characteristic through B. We obtain sufficient conditions for the uniqueness of the solution of the problem L[u] = f, dnu: = k(y)uxdy – uydx|γ0 = = Ψ(s) for a “general” function k(y), when r(x, y) is not necessarily zero and Γ1 is of a more general form then in the papers of V. P. Egorov [6], [7].
Über das Verhalten der Lösungen der Maxwellschen Randwertaufgabe in Gebieten mit Kegelspitzen
Authors: Saranen J. , Leis R.
Published: March 2007

We study the behavior of the solution E of the Maxwell's boundary value problem ∇ × ∇ × E + λE = F, n × E|r = 0 in domains Ω which have conical boundary points. In a neighbourhood K(R) = B(a,R) ∩ Ω of a singular boundary point a the field E is expanded using a theorem of N. Weck. It e.g. turns out that the solution lies in H1(3)(K(R)) if K(R) is convex.
The effect of a thin inclusion of high rigidity in an elastic body
Authors: Caillerie D. , Nedelec J. C.
Published: March 2007

We study an elastic body comprising an inclusion whose thickness is 2ϵ and for which Lamé's constants are λϵ and μ. We are interested in the limit behaviour of the inclusion, when ϵ → 0 and μϵ → ϵ; that is when the inclusion becomes thiner and more rigid. Different behaviours are possible, according to the rate at which μϵ converges to infinity; the limit inclusion may “vanish” if it is not very rigid, but also it may be entirely solid.
Scattering of elastic waves through a heterogeneous medium
Authors: Codegone M. , Leis R.
Published: March 2007

In this paper we study the elastic wave diffraction in R3 through a heterogeneous medium, with periodic structure, which occupies a bounded domain. We show that, as the period tends to zero, the solution tends, in some sense, to the solution corresponding to the diffraction by an obstacle made of the classical “homogenized medium”. An analogous result is also proved for the scattering frequencies and the associated scattering functions.
Discontinuous self‐excited systems: An asymptotic analysis
Authors: Granoff B. , Freedman M. I. , Ludwig D.
Published: March 2007

In this paper we derive a uniformly valid asymptotic approximation of the periodic solution of a self‐excited system given by the differential equation

equation image

and β1,β2, are positive constants. By uniformly valid asymptotic approximation we mean that no secular terms are present. Our procedure makes use of a nonlinear change of independent variable that transforms the problem from one in which the discontinuities are ϵ dependent to one in which the discontinuities are ϵ independent. We obtain an asymptotic approximation up to order ϵ of the periodic solution and an asymptotic approximation up to order ϵ2 of the period. Some comparisons between our asymptotic results and numerically derived results are given. Application of our technique to other examples of self‐excited systems is discussed. The equation

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is investigated in detail.