bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms underlying the inability to induce area CA1 LTP in the mouse after traumatic brain injury
Authors: Schwarzbach E. , Bonislawski D.P. , Xiong G. , Cohen A.S. 
Published: April 2006

AbstractTraumatic brain injury (TBI) is a significant health issue that often causes enduring cognitive deficits, in particular memory dysfunction. The hippocampus, a structure crucial in learning and memory, is frequently damaged during TBI. Since long‐term potentiation (LTP) is the leading cellular model underlying learning and memory, this study was undertaken to examine how injury affects area CA1 LTP in mice using lateral fluid percussion injury (FPI). Brain slices derived from FPI animals demonstrated an inability to induce LTP in area CA1 7 days postinjury. However, area CA1 long‐term depression could be induced in neurons 7 days postinjury, demonstrating that some forms of synaptic plasticity can still be elicited. Using a multidisciplined approach, potential mechanisms underlying the inability to induce and maintain area CA1 LTP were investigated. This study demonstrates that injury leads to significantly smaller N‐methyl‐D‐aspartate potentials and glutamate‐induced excitatory currents, increased dendritic spine size, and decreased expression of α‐calcium calmodulin kinase II. These findings may underlie the injury‐induced lack of LTP and thus, contribute to cognitive impairments often associated with TBI. Furthermore, these results provide attractive sites for potential therapeutic intervention directed toward alleviating the devastating consequences of human TBI. © 2006 Wiley‐Liss, Inc.
Rat Schwann cells express M1–M4 muscarinic receptor subtypes
Authors: Loreti Simona , Vilaró M. Teresa , Visentin S. , Rees H. , Levey Allan I. , Tata Ada Maria 
Published: April 2006

AbstractThe expression of different muscarinic receptor subtypes was analyzed in immature Schwann cells obtained from sciatic nerve of 2‐day neonatal rats. By using RT‐PCR analysis, we demonstrated the presence of M1, M2, M3, and M4 receptor subtypes in cultured Schwann cells, with M2 displaying the highest expression levels. Muscarinic subtypes were also quantified by immunoprecipitation and [3H]QNB binding. With this approach, we found the levels of receptor expression to be M2 > M3 > M1. M4 is expressed at very low levels, and M5 receptor was not detectable. Moreover, we also demonstrated that stimulation of the receptors by muscarinic agonists activates previously described signal transduction pathways, leading to a decrease of cAMP and an increase of IP3 levels not associated with an efficient intracellular Ca2+ release. The presence and activity of particular muscarinic receptors in immature Schwann cells suggest that ACh may play an important role in Schwann cell development. © 2006 Wiley‐Liss, Inc.
Walker detection in outdoor scenes using spatial‐temporal feature analysis of variation regions
Authors: Haga Tetsuji , Sumi Kazuhiko , Yagi Yasushi 
Published: April 2006

AbstractWe propose an image processing algorithm to detect walkers in outdoor images containing movement in the background such as swaying trees or irregular reflections from water. Previously proposed methods to detect walkers focus on the fact that locally distributed movement is reinforced along a spatial and temporal path marked out by an object such as a human that moves at approximately a constant speed and in a straight line while other background movement tends to cancel itself out. However, false alarms can occur with methods that are based on the time‐averaged strength of movement due to mistaken associations between moving objects and the fact that temporary movement in high‐contrast areas can significantly raise the average value. In our method we use features based on a spatially averaged strength of movement and the uniformity of movement over time in addition to the time‐averaged strength of movement, attempting to distinguish walkers from background movement within a feature space made up of these three features. In experiments with real images we have confirmed that the proposed method can reduce the rate of both false positives and false negatives compared to a method that focuses only on the time‐averaged strength of movement. In addition, we have constructed an on‐line system to implement the proposed method and the results of evaluation experiments conducted in a real‐life environment over a period of two weeks show that we were able to obtain a level of performances in which the failure rate was less than 1 percent and false alarms occurred less than three times per day. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(7): 37–46, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20295
Measurement of neuromagnetic fields accompanying movements by patient with acute stroke
Authors: Kotani Kentaro , Esaka Shigeaki , Yamada Makoto , Deguchi Jun , Horii Ken , Tonoike Mitsuo , Noguchi Taro 
Published: April 2006

AbstractThe recovery mechanism of stroke patients with motion disorder is becoming clear through observation of changes in the activated area in the brain cortex, using brain function imaging. At the present stage, however, consistent results have not been obtained. Consequently, this study attempts an analysis of the neuromagnetic fields by combining the conventional equivalent current dipole method and the MCE method, which can reveal changes in multiple activity sources accompanying the recovery of brain function by stroke patients and those observable in healthy subjects. In the experiment, button‐pressing by the thumb is performed by a patient group and a normal group, and the neuromagnetic field response and the force of the motion are simultaneously measured. Thus, the task consists of simple button‐pressing motion and the generation of a force of specified magnitude. In the normal group, activation is observed in the motor area on the other side of the moving limb. In stroke patients, on the other hand, activation is observed on the same side as the moving limb, which agrees with the results of preceding studies. Neural activity is sometimes observed near the damaged lesion, suggesting that the brain on the ipsilateral hemisphere of the moving limb, or neural activity near the damaged lesion, is enhanced in the recovery of motor function after an acute stroke. It is concluded that a temporal course of changes in the activated area in the brain of patients with acute stroke, which exhibits patterns different from the neuromagnetic field of normal subjects, can be observed. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(7): 12–25, 2006; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/scj.20448
Neural regression model, resampling and diagnosis
Authors: Tsujitani Masaaki , Aoki Masahiko 
Published: April 2006

AbstractIn this article logistic regression model is highlighted using a feedforward neural network model. Suggested here is a simple more precise prognostic technique by incorporating follow‐up data in the development of the model when the data consist of grouped binary response and a set of predictor variables, which is closely related to classical logistic regression model. Statistical techniques are formulated in terms of the principle of the likelihood when a resampling process such as bootstrapping and cross‐validation is applied. We then attempt to determine the number of units in the hidden layer, to verify the asymptotic χ2behavior of the deviance for the goodness‐of‐fit test of the model, to detect inappropriate influential observations and outliers, and to improve the goodness‐of‐fit test of the neural network model. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(6): 13–20, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20497
Hypocalcaemia and Parathyroid Hormone Assay Following Total Thyroidectomy: Predicting the Future
Authors: Wong C. , Price S. , Scott‐Coombes D. 
Published: April 2006

AbstractBackgroundAmbulatory surgery (23:59‐hour hospital stay) is gaining popularity in endocrine surgery. Hypocalcaemia is common following total thyroidectomy. Identifying patients with low risk of hypocalcaemia may facilitate early discharge (24‐hour stay).MethodsWe conducted a prospective study including all patients undergoing total thyroidectomy. Blood samples were taken immediately following skin closure and the following morning for parathyroid hormone (PTH) and calcium measurement. Calcium supplements were routinely given when serum calcium was below 2.0 mmol/l.ResultsThirty patients (27 females, 3 males) underwent total thyroidectomy (including 4 nodal dissection) for multinodular goitre (14), Graves’ disease (11), papillary (4) and follicular (1) thyroid carcinoma. Twelve patients developed symptomatic transient hypocalcaemia. Based on morning calcium of <2.0 mmol/l as trigger for calcium supplementation, 8 patients received calcium supplement with 4 false negatives, resulting in a specificity of 94.4%, sensitivity of 66.7%, positive predictive value (PPV) of 88.9% and negative predictive value (NPV) of 81%. Based on PTH levels (<1.5 pmol/l) immediately following skin closure, 11 patients would receive calcium supplement, with 1 false negative resulting in a specificity of 83.3%, sensitivity of 91.7%, PPV of 78.6% and NPV of 93.8%. If supplementation is based on PTH levels (<1.5 pmol/l) immediately following skin closure and morning calcium level (<2.0 mmol/l), all 12 symptomatic patients will be correctly treated, with 4 false positives resulting in a combined specificity of 77.8%, sensitivity of 100%, PPV of 75% and NPV of 100%.ConclusionsCombining the immediate postoperation PTH levels (<1.5 pmol/l) and morning serum calcium (<2.0 mmol/l) can accurately identify patients at risk of hypocalcaemia following total thyroidectomy, allowing safe, early discharge.
The hydrodynamic stability of flow over Kramer-type compliant surfaces. Part 2. Flow-induced surface instabilities
Authors: Carpenter P. W. , Garrad A. D. 
Published: April 2006

The flow-induced surface instabilities of Kramer-type compliant surfaces are investigated by a variety of theoretical approaches. This class of instability includes all those modes of instability for which the mechanism of generation involves essentially inviscid processes. The results should be applicable to all compliant surfaces that could be modelled theoretically by a thin elastic plate, with or without applied longitudinal tension, supported on a springy elastic foundation. with or without a viscous fluid substrate; material damping is also taken into account through the viscoelastic properties of the solid constituents of the coatings.The simple case of a potential main flow is studied first. The eigenmodes for this case are subjected to an energy analysis following the methods of Landahl (1962). Instabilities that grow both in space and time are then considered, and absolute and convective instabilities identified and analysed.The effects of irreversible processes on the flow-induced surface instabilities are investigated. The shear flow in the boundary layer gives rise to a fluctuating pressure component which is out of phase with the surface motion. This leads to an irreversible transfer of energy from the main stream to the compliant surface. This mechanism is studied in detail and is shown to be responsible for travelling-wave flutter. Simple results are obtained for the critical velocity, wavenumber and stability boundaries. These last are shown to be in good agreement with the results obtained by the numerical integration of the Orr–Sommerfeld equation. An analysis of the effects of a viscous fluid substrate and of material damping is then carried out. The simpler inviscid theory is shown to predict values of the maximum growth rate which are, again, in good agreement with the results obtained by the numerical integration of the Orr–Sommerfeld equation provided that the instability is fairly weak.Compliant surfaces of finite length are analysed in the limit as wave-length tends to zero. In this way the static-divergence instability is predicted. Simple formulae for critical velocity and wavenumber are derived. These are in exact agreement with the results of the simpler infinite-length theory. But, whereas a substantial level of damping is required for the instability on a surface of infinite length, static divergence grows fastest in the absence of damping on a surface of finite length.
One-dimensional models for topographic Rossby waves in elongated basins on thef-plane
Authors: Stocker Thomas , Hutter Kolumban 
Published: April 2006

Topographic Rossby waves in elongated basins on thef-plane are studied by transforming the linear boundary-value problem for the mass transport stream function into a class of two-point boundary-value problems of which the independent spatial variable is the (curved) basin axis. The procedure for deriving the substitute problems is theMethod of Weighted Residuals. What emerges is a vector differential equation and associated boundary conditions, its dimension indicating the order of the approximate model. It is shown that each substitute problem in the class entails the qualitative features typical of topographic waves, and increasing the order of the model corresponds to higher-order approximations. Equations are explicitly presented for cross-sectional distributions of the lake topography which has a power-law representation and permits the analysis of weak and strong topographies.Straight channels in which the depth profile does not change with position along the axis are studied in detail. The dispersion relation is discussed and dispersion curves are shown for the three lowest-order models. Convergence properties are thereby uncovered and phase speed and group velocity properties are found as they depend on wavenumber and topography. Further, for the lowest two modes, cross-channel stream-function distributions are presented. Apart from further convergence properties these distributions show that forU-shaped channels wave activity is nearer to the shore than forV-shaped channels, important information in the design of mooring systems.An analysis of topographic Rossby wave reflection follows, which emphasizes the importance of the depth profile in the reflecting zone. Based on these results some lake solutions are presented.
Acoustic monitoring of ocean gyres
Authors: Munk Walter 
Published: April 2006

There has been an increased interest in ocean phenomena with horizontal scales comparable to the radius of the Earth, and timescales of years and beyond. These phenomena occur in the presence of intense processes of higher spatial and temporal frequency. An observational programme for the large-scale phenomena has an inherent advantage if it can rely on measurements that are, by their very nature, integrated moments over the prerequisite scale.The oceans provide an excellent medium for transmitting sound waves of low frequency, as demonstrated in the closing days of World War II, and subsequently confirmed by a 20000 km acoustic transmission between Perth, Australia and Bermuda. For the last six years we have been developing a method (Ocean Acoustic Tomography) to take advantage of the favourable ocean acoustic properties. We measure travel time Δ+ from mooring m to mooring n (positive x), and Δ− from n to m. The sum Δ+ + Δ− then gives information about the sound speed C (e.g. temperature) averaged along the acoustic ray path; the difference Δ+ – Δ− gives information about the x-component u of current velocity. The recorded acoustic signal can be decomposed into 10-20 distinct ray arrivals Δi, each with a distinct ray path and associated depth-weighting of the ocean column; the ray travel times can be inverted to yield information about the depth profiles C(z) and u(z). The product 〈C〉 〈u〉 of these range-averaged quantities is related to the climatological large-scale heat flux; the space-time average $\overline{\langle \delta C\,\delta u\rangle}$ is related to the eddy heat flux, and can be estimated by measuring the difference variance (Δ+) – variance (Δ−).
An experiment on boundary mixing: mean circulation and transport rates
Authors: Phillips O. M. , Shyu Jinn-Hwa , Salmun Haydee 
Published: April 2006

An experiment is described in which a turbulent boundary layer was generated along a sloping wall of a laboratory tank containing salt-stratified fluid. Initially, the pycnocline separating the upper fresh-water layer from the lower saline layer was relatively thin; it thickened in response to the mixing as the experiment proceeded. Two types of mean circulation developed as a result of the boundary mixing. In the boundary layer, counterflowing mean streams were observed that augmented the diffusion of salt up- and downslope. This augmented dispersion in turn tended to spread the salt beyond the depth range of the pycnocline in the ambient fluid, producing a mean convergence in the boundary layer and intrusions from the layer into the ambient fluid.The evolving density structure in the ambient fluid was measured by conductivity-probe traverses, from which the net buoyancy flux (or salt flux) and volume flux in the boundary layer were determined. The level of zero volume flux was found to coincide closely with the level of maximum stability frequency N, so that the buoyancy transport across this level was entirely the result of turbulent dispersion in the boundary layer. At other levels, the convective transports up and down contribute significantly. A simple theory provides scaling in terms of the laboratory parameters; in terms of the inferred overall turbulent viscosity νe, the buoyancy transport resulting from boundary-layer dispersion was found to be
\[
F_{\rm B} = 0.60 \left\{\frac{\nu_{\rm e}N(z)}{\sin\theta}\right\}^{\frac{3}{2}}\cos^2\theta,
\]
and the intrusion velocity into the ambient fluid is
\[
v_1 = 0.42\frac{\nu_{\rm e}^{\frac{3}{2}}}{N^{\frac{1}{2}}h^2}\frac{\cos^2\theta}{(\sin\theta)^{\frac{3}{2}}},
\]
where θ is the angle of the sloping bed. These expressions must become invalid when θ becomes vanishingly small; their application to estuarine and continental slope flows is discussed briefly.
Low-Reynolds-number flow past cylindrical bodies of arbitrary cross-sectional shape
Authors: Lee S. H. , Leal L. G. 
Published: April 2006

A numerical implementation of the method of matched asymptotic expansions is proposed to analyse two-dimensional uniform streaming flow at low Reynolds number past a straight cylinder (or cylinders) of arbitrary cross-sectional shape. General solutions for both the Stokes and Oseen equations in two dimensions are expressed in terms of a boundary distribution of fundamental single- and double-layer singularities. These general solutions are then converted to integral equations for the unknown distributions of singularity strengths by application of boundary conditions at the cylinder surface, and matching conditions between the Stokes and Oseen solutions. By solving these integral equations, using collocation methods familiar from three-dimensional application of ‘boundary integral’ methods for solutions of Stokes equation, we generate a uniformly valid approximation to the solution for the whole domain.We demonstrate the method by considering, as numerical examples, uniform flow past an elliptic cylinder, uniform flow past a cylinder of rectangular cross-section, and uniform flow past two parallel cylinders which may be either equal in radius, or of different sizes.
The interaction of an oblique shock wave with a laminar boundary layer revisited. An experimental and numerical study
Authors: Degrez G. , Boccadoro C. H. , Wendt J. F. 
Published: April 2006

An investigation of an oblique shock wave/laminar boundary layer interaction is presented. The Mach number was 2.15, the Reynolds number was 105 and the overall pressure ratio was 1.55. The interation has been demonstrated to be laminar and nominally two-dimensional. Experimental results include pressure distributions on the plate and single component laser-Doppler velocimetry velocity measurements both in the attached and separated regions.The numerical results have been obtained by solving the full compressible Navier-Stokes equations with the implicit approximate factorization algorithm by Beam & Warming (1980). Comparison with experimental data shows good agreement in terms of pressure distributions, positions of separation and reattachment and velocity profiles.
Transcritical two-layer flow over topography
Authors: Melville W. K. , Helfrich Karl R. 
Published: April 2006

The evolution of weakly-nonlinear two-layer flow over topography is considered. The governing equations are formulated to consider the effects of quadratic and cubic nonlinearity in the transcritical regime of the internal mode. In the absence of cubic nonlinearity an inhomogeneous Korteweg-de Vries equation describes the interfacial displacement. Numerical solutions of this equation exhibit undular bores or sequences of Boussinesq solitary waves upstream in a transcritical regime. For sufficiently large supercritical Froude numbers, a locally steady flow is attained over the topography. In that regime in which both quadratic and cubic nonlinearity are comparable, the evolution of the interface is described by an inhomogeneous extended Kortewegde Vries (EKdV) equation. This equation displays undular bores upstream in a subcritical regime, but monotonic bores in a transcritical regime. The monotonic bores are solitary wave solutions of the corresponding homogeneous EKdV equation. Again, locally steady flow is attained for sufficiently large supercritical Froude numbers. The predictions of the numerical solutions are compared with laboratory experiments which show good agreement with the solutions of the forced EKdV equation for some range of parameters. It is shown that a recent result of Miles (1986), which predicts an unsteady transcritical regime for single-layer flows, may readily be extended to two-layer flows (described by the forced KdV equation) and is in agreement with the results presented here.Numerical experiments exploiting the symmetry of the homogeneous EKdV equation show that solitary waves of fixed amplitude but arbitrary length may be generated in systems described by the inhomogeneous EKdV equation.
Lagrangian moments and mass transport in Stokes waves
Authors: Longuet-Higgins Michael 
Published: April 2006

The orbital motions in surface gravity waves are of interest for analysing wave records made by accelerometer buoys. In this paper we derive some exact expressions for the first, second and third cumulants of the vertical orbital displacements in a regular Stokes wave of finite amplitude in terms of previously known integral quantities of the wave: the kinetic and potential energies, the phase speed c and the mass-transport velocity U at the free surface. These results generalize a remarkably simple relation found previously between the Lagrangian-mean surface level and the product Uc.Expansions are given in powers of the wave steepness parameter ak which show that the third Lagrangian cumulant is very small – of order (ak)6, indicating a high degree of vertical symmetry in the orbit. This contrasts with the situation in random waves, where the third cumulant is of order (ak)4 only. It is shown that the increased skewness in random waves is due mainly to an O(ak)2 shift in the Lagrangian mean level of individual waves. Such shifts in mean level may be too gradual to be fully detected by some accelerometer buoys. In that case the apparent skewness will be reduced.