bluuebunny/crossref_metadata_2025 huggingface dataset:
RGS9-2 modulates D
2
dopamine receptor-mediated Ca
2+
channel inhibition in rat striatal cholinergic interneurons
Authors: Cabrera-Vera Theresa M. , Hernandez Salvador , Earls Laurie R. , Medkova Martina , Sundgren-Andersson Anna K. , Surmeier D. James , Hamm Heidi E.
Published: November 2004

Regulator of G protein signaling (RGS) proteins negatively regulate receptor-mediated second messenger responses by enhancing the GTPase activity of Gα subunits. We describe a receptor-specific role for an RGS protein at the level of an individual brain neuron. RGS9-2 and Gβ
5
mRNA and protein complexes were detected in striatal cholinergic and γ-aminobutyric acidergic neurons. Dialysis of cholinergic neurons with RGS9 constructs enhanced basal Ca
2+
channel currents and reduced D
2
dopamine receptor modulation of Cav2.2 channels. These constructs did not alter M
2
muscarinic receptor modulation of Cav2.2 currents in the same neuron. The noncatalytic DEP-GGL domain of RGS9 antagonized endogenous RGS9-2 activity, enhancing D
2
receptor modulation of Ca
2+
currents.
In vitro
, RGS9 constructs accelerated GTPase activity, in agreement with electrophysiological measurements, and did so more effectively at Go than Gi. These results implicate RGS9-2 as a specific regulator of dopamine receptor-mediated signaling in the striatum and identify a role for GAP activity modulation by the DEP-GGL domain.
Remote hot spots mediate protein substrate recognition for the Cdc25 phosphatase
Authors: Sohn J. , Kristjánsdóttir K. , Safi A. , Parker B. , Kiburz B. , Rudolph J.
Published: November 2004

Cdc25B is a phosphatase that catalyzes the dephosphorylation and activation of the cyclin-dependent kinases, thus driving cell cycle progression. We have identified two residues, R488 and Y497, located >20 Å from the active site, that mediate protein substrate recognition without affecting activity toward small-molecule substrates. Injection of Cdc25B wild-type but not the R488L or Y497A variants induces germinal vesicle breakdown and cyclin-dependent kinase activation in
Xenopus
oocytes. The conditional knockout of the
cdc25
homolog (
mih1
) in
Saccharomyces cerevisiae
can be complemented by the wild type but not by the hot spot variants, indicating that protein substrate recognition by the Cdc25 phosphatases is an essential and evolutionarily conserved feature.
Mechanisms of Naringenin‐induced Apoptotic Cascade in Cancer Cells: Involvement of Estrogen Receptor a and ß Signalling
Authors: Totta Pierangela , Acconcia Filippo , Leone Stefano , Cardillo Irene , Marino Maria
Published: November 2004

The flavanone naringenin (Nar), especially abundant in the Mediterranean diet, is reported to have anti‐proliferative effects in many cancer cell lines. Antioxidant activities, kinase and glucose uptake inhibition have been proposed as molecular mechanisms for these effects. In addition, an anti‐estrogenic activity has been observed but, at the present, it is poorly understood whether this latter activity could play a role in the Nar anti‐tumoral effects. Here, we tested the ability of Nar to activate a specific, rapid signal transduction pathway committed to the generation of an apoptotic cascade in the presence of one of the two estrogen receptor (ER) isoforms (i.e., ERα or ERβ). Cancer cells containing transfected (human cervix epitheloid carcinoma HeLa cells) or endogenous ERα (human hepatoma HepG2 cells) or ERβ (human colon adenocarcinoma DLD‐1 cells) were used. Our results show that Nar exerts an anti‐proliferative effect only in the presence of ERα or ERβ. Moreover, Nar stimulation induces the activation of p38/MAPK leading to the pro‐apoptotic caspase‐3 activation and to the poly(ADP‐ribose) polymerase cleavage in all cancer cell lines considered. Notably, Nar shows an anti‐estrogenic effect only in ERα containing cells; whereas in ERβ containing cells, Nar mimics the 17β‐estradiol effects. These findings indicate new steps in the mechanism underlying ER‐dependent anti‐proliferative effects of Nar suggesting new potential chemopreventive actions of flavonoids on cancer growth. IUBMB Life, 56: 491‐499, 2004
Emerging Role of P53, Bcl‐2 and Telomerase Activity in Egyptian Breast Cancer Patients
Authors: Swellam Menha , Ismail Manal , Eissa Sanaa , Hamdy Mohamed , Mokhtar Nadia
Published: November 2004

Apoptotic cell death represents an important mechanism for the precise regulation of cell numbers, and a defense mechanism against tumor cells. Both bcl‐2 and mutant p53 gene products have been involved in apoptotic pathways. On the other hand, cell proliferation capacity and tumorgenesis have been controlled by telomerase. The purpose of our study is to assess the prognostic significance of additional markers implicated in apoptosis and tumorgenesis. Fifty‐one fresh tissue samples of primary breast carcinoma and 26 tissue samples of benign breast lesions were included in this study. Expression of bcl‐2 in cell lysates and mutant p53 protein in nuclear fraction were measured by Oncogene Science EIA procedures. Telomerase activity was analyzed using the Telomerase‐PCR‐ELISA based on the TRAP (telomerase repeat amplification protocol) method. On the same specimens, steroid hormone receptors (ER and PgR) were measured in cytosol fraction using Abbott EIA assays. In addition, information regarding surgical‐pathological features of the tumor was obtained. Univariate and Multivariate analysis was done to identify variables predictive of poor prognosis. Significant expression of bcl‐2, mutant p53 proteins and relative telomerase activity were observed in malignant cases when compared to benign ones. Univariate analysis revealed significant association in the level of both mutant p53 and relative telomerase activity with tumor size and disease recurrence. Moreover, telomerase activity was significantly expressed in late stages than early ones. Multivariate analysis revealed that bcl‐2, mutant p53, telomerase activity, PgR and age were independent prognostic factors. Among a panel of molecular genetic factors investigated, mutant p53 and relative telomerase activity were strongly associated with disease recurrence; hence they exert a significant prognostic role in breast cancer. IUBMB Life, 56: 483‐490, 2004
I. The Southern Bluefin Tuna Arbitration
Authors: Evans Malcolm D. , Boyle Alan
Published: November 2004

Readers of last October's I.C.L.Q. will recall that this case started life in the International Tribunal for the Law of the Sea when Australia and New Zealand were granted provisional measures against Japanese high seas tuna fishing in the Pacific.1 That Tribunal had held that the provisions of the 1982 UN Convention on the Law of the Sea (“1982 UNCLOS”) invoked by Australia and New Zealand appeared to afford a basis on which the jurisdiction of an arbitral tribunal might be founded; that the fact that the 1993 Convention on Conservation of Southern Bluefin Tuna applied between the parties did not preclude recourse to the compulsory dispute settlement procedures in Part XV of the 1982 UNCLOS; and that an arbitral tribunal would prima facie have jurisdiction over the merits of the dispute.2 Notwithstanding this necessarily provisional view, when the parties then proceeded to arbitration, Japan maintained its initial preliminary objections, and the award handed down in August 2000 thus deals only with the jurisdiction of the arbitrators.3 The facts and background to the case are set out in the earlier case-note and need not be repeated here.
III. Competition
Authors: McMahon Joe , Lane Robert
Published: November 2004

The period under review (Autumn 1999–Spring 2001) saw a number of important cases decided by the Court of Justice involving breaches of Article 81(1). Pre-eminent are three judgments involving cartels and one involving distribution contracts.
The Scottish Arrestment and the English Freezing Order
Authors: Aird Richard
Published: November 2004

This comparison involves the study of two very different forms of remedy. These are the Scottish Arrestment and the English Freezing Order.2 The Freezing Order is a relatively recent common law creation which contains features unusual amongst Convention jurisdictions. The continental origins of the Arrestment over 400 years ago, and its existence in a jurisdiction based upon the Civil Law unaltered by the Code Napoleon, have given rise to a remedy which is a member of the same family as its continental equivalents but different again. Indeed as we shall see, these measures are so different that most of the possible features of remedies of their type lie in the contrast.
Decisions of International Tribunals: The International Court of Justice
Authors: Evans Malcolm D
Published: November 2004

On 16 March 2001 the International Court of Justice gave judgment in what was then its most longrunning case. It was in 1987 that Qatar and Bahrain had begun a process of attempting to agree upon the submission of their differences to the Court, but although they were able to agree upon the subject matter in dispute, they could not agree upon its legal characterization and the manner in which the dispute should be placed before the Court. That notwithstanding, and basing itself upon the agreed minutes of a meeting held at Doha in December 1990, Qatar unilaterally instituted proceedings against Bahrain on 8 July 1991. Bahrain raised preliminary objections to the jurisdiction of the Court and the admissibility of the case which were first addressed by the Court in its judgment of July 19941 and, following a reformulation of elements of the Qatari application in November 1994, the application was declared admissible in February 1995.2 During the course of the subsequent written pleadings a further dispute arose concerning the authenticity of 82 documents annexed to the Qatar Memorial and, following exchanges on the matter, Qatar announced that it would not rely on the disputed documents.3 Oral hearings were held in May 2000 and judgment given some ten months later. The two principal elements of the case concern, first, the disputed title to, and status of, a number of islands, maritime features and a portion of the Qatar peninsula and, secondly, the course of the maritime boundaries between them. The case was extremely complex, with disputed characterizations of the physical and legal
Judicial Approaches to the Human Rights Act
Authors: Bonner David , Fenwick Helen , Harris-Short Sonia
Published: November 2004

The case law generated in just over two years' operation of the Human Rights Act 1998 (HRA), enables stocktaking rather than definitive appraisal.1 This article begins by recalling the markedly contrasting roles in United Kingdom law of the European Convention on Human Rights (ECHR) before and after the HRA, the better to appreciate judicial approaches to, and use of, the HRA in the areas surveyed. The second part of the article focuses on judicial use of key provisions of the HRA to interpret primary legislation said to conflict with one or more Convention rights and on judicial use of the power to make a declaration of incompatibility. It considers a selection of decisions, principally of the House of Lords and the Court of Appeal, which raise important points regarding the purpose and scope of the HRA as a constitutional document and indicate judicial uncertainty as to how the HRA should be conceptualised, interpreted and applied. With this emerging picture of a cautious and uncertain judiciary in mind, the final two sections of the article give detailed consideration to the post-HRA jurisprudence within two discrete areas of English law. Part III explores the impact of the HRA on judicial approaches to the clash between the freedoms of expression and assembly, on the one hand, and public order, on the other. Part IV considers the ‘use and abuse’ of the HRA and of Article 8 ECHR in private law family disputes. Finally, certain tentative conclusions as to the perhaps disappointing story of the HRA so far, will be proffered.
The High Pressure Rheology of Mixtures
Authors: Bair Scott
Published: November 2004

The Newtonian mixing rules for several binary systems have been experimentally investigated. Some systems show non-ideal mixing response and for some systems the non-ideal response is pressure-dependent, yielding an opportunity for manipulation of the pressure-viscosity behavior to advantage. The mixing of differing molecular weight “straight cuts” can produce very different pressure-viscosity response. This behavior underscores the difficulty in predicting the pressure-viscosity coefficient based upon chemical structure and ambient viscosity since the molecular weight distribution is also important, but it also provides another opportunity to control the high-pressure response by blending. The first experimental observation of double shear-thinning within a single flow curve is reported. Blending then provides the capability of adjusting not only the Newtonian viscosity but also the non-Newtonian shear-thinning response as well.
Some Remarks on the Validity of Reynolds Equation in the Modeling of Lubricant Film Flows on the Surface Roughness Scale
Authors: Almqvist T. , Larsson R.
Published: November 2004

The objective of this paper is to investigate the flow in a lubricant film on the surface roughness scale and to compare the numerical solutions obtained by two different solution approaches. This is accomplished firstly by the CFD-approach (computational fluid dynamic approach) where the momentum and continuity equations are solved separately, and secondly the Reynolds equation approach, which is a combination and a simplification of the above equations. The rheology is assumed to be both Newtonian and non-Newtonian. An Eyring model is used in the non-Newtonian case. The result shows that discrepancies between the two approaches may occur, primarily due to a singularity which appears in the momentum equations when the stresses in the lubricant attain magnitudes that are common in EHL. This singularity is not represented by the Reynolds equation. If, however, the rheology is shifted to a non-Newtonian Eyring model the deviations between the two solution approaches is removed or reduced. The second source of discrepancies between the two approaches is the film thickness to wavelength scale ω. It will be shown that the Reynolds equation is valid until this ratio is approximately O10−2.
A Coupled Zig-Zag Third-Order Theory for Piezoelectric Hybrid Cross-Ply Plates
Authors: Kapuria S.
Published: November 2004

A new zig-zag coupled theory is developed for hybrid cross-ply plates with some piezoelectric layers using third-order zig-zag approximation for the inplane displacements and sublayer wise piecewise linear approximation for the electric potential. The theory considers all electric field components and can model open and closed-circuit boundary conditions. The deflection field accounts for the transverse normal strain due to the piezoelectric d33 coefficient. The displacement field is expressed in terms of five displacement variables (which are the same as in FSDT) and electric potential variables by satisfying exactly the conditions of zero shear stresses at the top and bottom, and their continuity at layer interfaces. The governing equations are derived from the principle of virtual work. Comparison of the Navier solutions for the simply-supported plates with the analytical three-dimensional piezoelasticity solutions establishes that the present efficient zig-zag theory is quite accurate for moderately thick plates.
Dynamic Response of a Clamped Circular Sandwich Plate Subject to Shock Loading
Authors: Qiu X. , Deshpande V. S. , Fleck N. A.
Published: November 2004

An analytical model is developed for the deformation response of clamped circular sandwich plates subjected to shock loading in air and in water. The deformation history is divided into three sequential stages and analytical expressions are derived for the deflection, degree of core compression, and for the overall structural response time. An explicit finite element method is employed to assess the accuracy of the analytical formulas for the simplified case where the effects of fluid-structure interaction are neglected. The sandwich panel response has only a low sensitivity to the magnitude of the core compressive strength and to the degree of strain hardening in the face-sheets. The finite element results confirm the accuracy of the analytical predictions for the rigid ideally plastic sandwich plates. The analytical formulas are employed to determine optimal geometries of the sandwich plates that maximize the shock resistance of the plates for a given mass. The optimization reveals that sandwich plates have a superior shock resistance relative to monolithic plates of the same mass.
The Effect of Warping Stress on the Lateral-Torsion Buckling of Cold-Formed Zed-Purlins
Authors: Chu, Xiao-ting , Li, and Long-yuan , Kettle Roger
Published: November 2004

An analytical model is developed for analysing the elastic lateral-torsion buckling of cold-formed zed-purlins with partially lateral restraint from metal sheeting. The model is used to estimate the effects of warping stresses on the lateral-torsion buckling behavior of cold-formed zed-purlins with various boundaries and interval braces provided by antisag bars. The results show that the warping stress only has remarkable influence on the lateral-torsion buckling when the boundary of the member is fixed and there is no antisag bar present.
Characterization of Plastic Deformation Induced by Microscale Laser Shock Peening
Authors: Chen Hongqiang , Kysar Jeffrey W. , Yao Y. Lawrence
Published: November 2004

Electron backscatter diffraction (EBSD) is used to investigate crystal lattice rotation caused by plastic deformation during high-strain rate laser shock peening in single crystal aluminum and copper sample on 110¯ and (001) surfaces. New experimental methodologies are employed which enable measurement of the in-plane lattice rotation under approximate plane-strain conditions. Crystal lattice rotation on and below the microscale laser shock peened sample surface was measured and compared with the simulation result obtained from FEM analysis, which account for single crystal plasticity. The lattice rotation measurements directly complement measurements of residual strain/stress with X-ray micro-diffraction using synchrotron light source and it also gives an indication of the extent of the plastic deformation induced by the microscale laser shock peening.
Combined Edge and Anisotropy Effects on Fickian Mass Diffusion in Polymer Composites
Authors: Aktas Levent , Hamidi Youssef K. , Altan M. Cengiz
Published: November 2004

The common methods used to determine the diffusion coefficients of polymer composites are based on the solution of Fickian diffusion equation in one-dimensional (1D) rectangular domain. However, these diffusivities usually involve errors primarily due to finite sample dimensions and anisotropy introduced by fiber reinforcements. In this study, the solution of transient, three-dimensional (3D) anisotropic Fickian diffusion equation is nondimensionalized using six parameters. The solution is then used to analyze the combined contribution of finite sample dimensions and anisotropy to the errors involved in diffusion constants calculated by 1D methods. The small time solution of the Fickian diffusion equation in 3D domain is used to analyze the slope used in diffusivity calculations. It is shown that the diffusion coefficient calculated by the 1D approach is exact only if the correct slope of percent mass gain versus root square time curve at t=0 is used. However, it has also been shown that depending on the part geometry and degree of anisotropy, there might be considerable differences between the measured slope from the experimental data and the actual slope at t=0. The mismatch between the slopes results in as much as 50% errors in estimates of diffusion coefficients. Using the 3D solution in nondimensional form, the magnitudes of these errors are studied. A least-square curve-fit method, which yields accurate anisotropic diffusion coefficients, is proposed. The method is demonstrated on artificially generated experimental data for a polymer composite containing 50% unidirectional reinforcement. The anisotropic diffusion coefficients used to generate the data are recovered with less than 1% error.
On Identification of Material Models When Nonrepeatability of Test Data is Present: Application to Textile Composites
Authors: Milani Abbas S. , Nemes James A.
Published: November 2004

Engineering test data occasionally violate assumptions underlying standard material model identification. Consequently, one has to apply appropriate remedies with respect to each violation to enhance the reliability of identified material parameters. This paper generalizes the use of the signal-to-noise weighting scheme when heteroscedasticity of test data are suspected. Different mathematical and practical aspects of the approach are discussed. Additionally, the ensuing weighted identification process is simplified to an equivalent standard form by means of a space transformation. Finally, the approach is applied to the identification of a nonlinear material model for textile composites, on both qualitative and quantitative levels.
Near-Contact Laser Surface Textured Dry Gas Seals
Authors: McNickle A. D. , Etsion I.
Published: November 2004

A new concept of a near-contact gas seal is experimentally investigated. A simulated gas face seal for a high-speed gas turbine engine is used for the investigation. A baseline conventional contacting-type seal is compared with an identical seal that was laser surface textured (LST) to turn it into a near-contact gas seal. Results show the potential benefits of the new concept in terms of smoother running, lower friction torque, and lower face temperature at 12,000 RPM over a range of face loading.
Nanomechanical and Nanotribological Properties of an Antiwear Tribofilm Produced from Phosphorus-Containing Additives on Boundary-Lubricated Steel Surfaces
Authors: Komvopoulos K. , Do V. , Yamaguchi E. S. , Ryason P. R.
Published: November 2004

Nanoindentation and nanotribological experiments were performed on an antiwear tribofilm produced from a blend consisting of gear base oil and a phosphorus-containing additive. Electrical contact resistance measurements were used to determine in situ the formation of the tribofilm on AISI steel surfaces at 100 °C under conditions favoring sliding in the boundary lubrication regime. Nanoindentation experiments were carried out with a surface force microscope on a small sector of a disk specimen that contained part of the wear track. A Berkovich diamond tip with a nominal radius of curvature equal to 100 nm was used to perform indentations on and off the wear track under a normal load between 100 and 600 μN. The phosphate tribofilm exhibited an average hardness of 6.0 GPa and reduced elastic modulus of 122.7 GPa compared to 12.5 GPa and 217.6 GPa of the steel substrate, respectively. In addition to the nanomechanical properties, the nanotribological properties of the tribofilm were evaluated in light of nanofriction tests performed with a 20 μm radius of curvature conical diamond tip under a normal load in the range of 100–200 μN. The original steel surfaces exhibited constant friction, whereas the wear track covered by the phosphate tribofilm revealed a higher and more fluctuating coefficient of friction, which is attributed to the roughness of the wear track and the greater plasticity of the tribofilm than the steel substrate.
A Mechanical Model for Low-Gravity Sloshing in an Axisymmetric Tank
Authors: Utsumi M.
Published: November 2004

A mechanical model for low-gravity sloshing in an axisymmetric tank is developed using a newly developed slosh analysis method. In this method, spherical coordinates, whose origin is at the top of the cone that is tangent to the tank at the contact line of the meniscus with the tank wall, are used to analytically determine the characteristic functions for an arbitrary axisymmetric tank for which it is customary to resort to numerical methods. By this means, fast and cost-efficient computation can be conducted. Parameters of the mechanical model are determined such that the frequency responses of the resultant force and moment to lateral excitation coincide with those of the actual sloshing system. Influences of the Bond number and the liquid-filling level on the parameters of the mechanical model are examined.
The effect of overlap-masking on binaural reverberant word intelligibility
Authors: Libbey Brad , Rogers Peter H.
Published: November 2004

Reverberation interferes with the ability to understand speech in rooms. Overlap-masking explains this degradation by assuming reverberant phonemes endure in time and mask subsequent reverberant phonemes. Most listeners benefit from binaural listening when reverberation exists, indicating that the listener’s binaural system processes the two channels to reduce the reverberation. This paper investigates the hypothesis that the binaural word intelligibility advantage found in reverberation is a result of binaural overlap-masking release with the reverberation acting as masking noise. The tests utilize phonetically balanced word lists (ANSI-S3.2 1989), that are presented diotically and binaurally with recorded reverberation and reverberation-like noise. A small room, 62 m3, reverberates the words. These are recorded using two microphones without additional noise sources. The reverberation-like noise is a modified form of these recordings and has a similar spectral content. It does not contain binaural localization cues due to a phase randomization procedure. Listening to the reverberant words binaurally improves the intelligibility by 6.0% over diotic listening. The binaural intelligibility advantage for reverberation-like noise is only 2.6%. This indicates that binaural overlap-masking release is insufficient to explain the entire binaural word intelligibility advantage in reverberation.
Constructing a cochlear transducer function from the summating potential using a low-frequency bias tone
Authors: Choi Chul-Hee , Chertoff Mark E. , Bian Lin , Lerner David
Published: November 2004

A new method is developed to construct a cochlear transducer function using modulation of the summating potential (SP), a dc component of the electrical response of the cochlea to a sinusoid. It is mathematically shown that the magnitude of the SP is determined by the even-order terms of the power series representing a nonlinear function. The relationship between the SP magnitudes and the second derivative of the transducer function was determined by using a low-frequency bias tone to position a high-frequency probe tone at different places along the cochlear transducer function. Two probe tones (6 kHz and 12 kHz) ranging from 70 to 90 dB SPL and a 25-Hz bias tone at 130 dB SPL were simultaneously presented. Electric responses from the cochlea were recorded by an electrode placed at the round window to obtain the SP magnitudes. The experimental results from eight animals demonstrated that the SP magnitudes as a function of bias levels are essentially proportional to the second derivative of a sigmoidal Boltzmann function. This suggests that the low-frequency modulated SP amplitude can be used to construct a cochlear transducer function.
Numerical simulation of acoustic streaming generated by finite-amplitude resonant oscillations in an enclosure
Authors: Aktas Murat K. , Farouk Bakhtier
Published: November 2004

Acoustic streaming motion in a compressible gas filled two-dimensional rectangular enclosure is simulated and the effects of the sound field intensity on the formation process of streaming structures are investigated numerically. The oscillatory flow field in the enclosure is created by the vibration of the left wall of the enclosure. The frequency of the wall vibration is chosen such that the lowest acoustic mode propagates along the enclosure. The fully compressible form of the Navier–Stokes equations is considered and an explicit time-marching algorithm is used to track the acoustic waves. The formation of the wave field in the enclosure is computed and fully described and the acoustic boundary layer development is predicted. The interaction of the wave field with viscous effects and the formation of streaming structures are revealed by time-averaging the solutions over a given period. The strength of the pressure waves associated with the acoustic effect and the resulting streaming flow pattern is found to be strongly correlated to the maximum displacement of the wall during a vibration cycle. The wave form determines the shape of the steady streaming structures in the oscillatory flow field.
Differential intracochlear recordings of ensemble background activity (EBA) (L)
Authors: Zhou Jianxun , Durrant John D. , Balaban Carey
Published: November 2004

The ensemble background activity (EBA) recorded from the round window has a spectral peak near 900 Hz that is generally attributed to spontaneous eighth-nerve activity, but other frequency regions are less well understood, including the issue of contribution of hair cell (HC) potentials. To further investigate the EBA, an intracochlear electrode pair was employed to record from the basal turn in guinea pig, applying the principles of differential recording. Results confirmed 900 Hz to be the dominant feature of the EBA power spectrum in/near quiet, wherein this peak was more robust in the average derivation and readily suppressed by kainic acid, consistent with its presumptive neural origin. Another broad spectral prominence, centered around 3000 Hz, was more prominent in the difference derivation, dominated the spectrum with increasing external (white) noise, and was much less sensitive to kainic acid, implying a predominantly HC origin. The findings demonstrate efficacy of intracochlear EBA recording, potentially extend EBA utility via the differential recording method, and further validate the EBA for monitoring spontaneous activity of the eighth nerve.
Improved scatterer property estimates from ultrasound backscatter for small gate lengths using a gate-edge correction factor
Authors: Oelze Michael L. , O’Brien William D.
Published: November 2004

Backscattered rf signals used to construct conventional ultrasound B-mode images contain frequency-dependent information that can be examined through the backscattered power spectrum. The backscattered power spectrum is found by taking the magnitude squared of the Fourier transform of a gated time segment corresponding to a region in the scattering volume. When a time segment is gated, the edges of the gated regions change the frequency content of the backscattered power spectrum due to truncating of the waveform. Tapered windows, like the Hanning window, and longer gate lengths reduce the relative contribution of the gate-edge effects. A new gate-edge correction factor was developed that partially accounted for the edge effects. The gate-edge correction factor gave more accurate estimates of scatterer properties at small gate lengths compared to conventional windowing functions. The gate-edge correction factor gave estimates of scatterer properties within 5% of actual values at very small gate lengths (less than 5 spatial pulse lengths) in both simulations and from measurements on glass-bead phantoms. While the gate-edge correction factor gave higher accuracy of estimates at smaller gate lengths, the precision of estimates was not improved at small gate lengths over conventional windowing functions.
Formant discrimination in noise for isolated vowels
Authors: Liu Chang , Kewley-Port Diane
Published: November 2004

Formant discrimination for isolated vowels presented in noise was investigated for normal-hearing listeners. Discrimination thresholds for F1 and F2, for the seven American English vowels /i, ɪ, ɛ, æ, ʌ, a, u/, were measured under two types of noise, long-term speech-shaped noise (LTSS) and multitalker babble, and also under quiet listening conditions. Signal-to-noise ratios (SNR) varied from −4 to +4 dB in steps of 2 dB. All three factors, formant frequency, signal-to-noise ratio, and noise type, had significant effects on vowel formant discrimination. Significant interactions among the three factors showed that threshold-frequency functions depended on SNR and noise type. The thresholds at the lowest levels of SNR were highly elevated by a factor of about 3 compared to those in quiet. The masking functions (threshold vs SNR) were well described by a negative exponential over F1 and F2 for both LTSS and babble noise. Speech-shaped noise was a slightly more effective masker than multitalker babble, presumably reflecting small benefits (1.5 dB) due to the temporal variation of the babble.
Cross-talk phenomena in a 1-3 connectivity piezoelectric composite
Authors: Wilm Mikaël , Armati Raphaël , Daniau William , Ballandras Sylvain
Published: November 2004

Many works have been devoted to the estimation of cross-talk effects in one-dimensional ultrasound probes. The main aspect limiting the interest of these works concerns the lack of control of the electrical boundary conditions applied to the array which may dramatically affect the results of cross-talk measurements. In this paper the concept of mutual admittances is recalled. Computations based on a periodic finite-element analysis are performed, jointly to measurements of cross talks in the case of a 1-3 connectivity piezoelectric composite. Quantitative comparisons show the capability of the proposed approach to predict almost all the contributions experimentally observed in a large frequency range.
Optimized shapes of oscillating resonators for generating high-amplitude pressure waves
Authors: Li Xiaofan , Finkbeiner Joshua , Raman Ganesh , Danielsb) Christopher , Steinetz Bruce M.
Published: November 2004

Several studies have proved that the geometry of an oscillating acoustic resonator strongly influences its resonance frequencies and the nonlinear standing pressure waveform generated within the cavity. The research presented herein uses a quasi-one-dimensional numerical model to solve the acoustic field and is validated by comparing with experimental results. A quasi-Newton type numerical scheme is used to optimize the axisymmetric cavity contour by maximizing the pressure compression ratio, defined as the ratio of maximum to minimum gas pressure at one end of the oscillating resonator. Cone, horn-cone, and cosine resonator contours are each optimized for a fixed amplitude of the periodic external force oscillating the cavity. Different optimized shapes are found when starting with different initial guesses, indicating multiple local extrema. The maximum pressure compression ratio value of 48 is found in an optimized horn-cone shape. This represents a 241% increase in the compression ratio over any previously published results.
APPLYING TABU SEARCH TO THE TWO-DIMENSIONAL ISING SPIN GLASS
Authors: LAGUNA MANUEL , LAGUNA PABLO
Published: November 2004

A variety of problems in statistical physics, such as Ising-like systems, can be modeled as integer programs. Physicists have relied mostly on Monte Carlo methods to find approximate solutions to these computationally difficult problems. In some cases, optimal solutions to relatively small problems have been found using standard optimization techniques, e.g., cutting plane and branch-and-bound algorithms. Motivated by the success of tabu search (TS) in finding optimal or near-optimal solutions to combinatorial optimization problems in a number of different settings, we study the application of this methodology to Ising-like systems. Particularly, we develop a TS method to find ground states of two-dimensional spin glasses. Our method performs a search at different levels of resolution in the spin lattice, and it is designed to obtain optimal or near-optimal solutions to problem instances with several different characteristics. Results are reported for computational experiments with up to 64×64 lattices.
FULL QCD ON APE100 MACHINES
Authors: ANTONELLI STEFANO , BELLACCI MARCO , DONINI ANDREA , SARNO RENATA
Published: November 2004

We present the first tests and results from a study of QCD with two flavours of dynamical Wilson fermions using the Hybrid Monte Carlo Algorithm (HMCA) on APE100 machines. The simulations have been performed on 64 lattice for the pure gauge HMCA and on 84, 123×32 lattices for full QCD configurations. We discuss the inversion algorithm for the fermionic operator, the methods used to overcome the problems arising using a 32 bit machine and the implementation of a new random number generator for APE100 machines.

We propose different scenarios for the simulation of physical observables, with respect to the memory capacity and speed of different APE100 configurations.
CRITICAL REVIEW OF FRACTAL IMAGE COMPRESSION
Authors: RAITTINEN HARRI , KASKI KIMMO
Published: November 2004

In this paper, fractal compression methods are reviewed. Three new methods are developed and their results are compared with the results obtained using four previously published fractal compression methods. Furthermore, we have compared the results of these methods with the standard JPEG method. For comparison, we have used an extensive set of image quality measures. According to these tests, fractal methods do not yield significantly better compression results when compared with conventional methods. This is especially the case when high coding accuracy (small compression ratio) is desired.
MONTE CARLO EVALUATION OF THE AHARONOV-BOHM EFFECT
Authors: JOHN GEORGE C. , SINGH VIJAY A.
Published: November 2004

The electron propagator in the Aharonov-Bohm effect is investigated using the Feynman path integral formalism. The calculation of the propagator is effected using a variation of the Metropolis Monte Carlo algorithm. Unlike “exact” calculations, our approach permits us to include a nonvanishing solenoid radius. We investigate the dependence of the resulting interference pattern on the magnetic field as well as the solenoid radius. Our results agree with the exact case in the limit of an infinitesimally small solenoid radius.
SYMMETRY DECOUPLING IN LINEAR ALGEBRAIC VARIATIONAL SCATTERING PROBLEMS
Authors: ZHAO MEISHAN
Published: November 2004

This paper discusses the symmetry decoupling in quantum mechanical algebraic variational scattering calculations by the generalized Newton variational principle. Symmetry decoupling for collisions involving identical particles is briefly discussed. Detailed discussion is given to decoupling from evaluation of matrix elements with nonzero total angular momentum. Example numerical calculations are presented for BrH2 and DH2 systems to illustrate accuracy and efficiency.
A MONTE CARLO SIMULATION OF A TWISTED NEMATIC LIQUID CRYSTAL DISPLAY
Authors: BERGGREN ELISABET , ZANNONI CLAUDIO , CHICCOLI CESARE , PASINI PAOLO , SEMERIA FRANCO
Published: November 2004

We present a Monte Carlo simulation of a model of a twisted nematic display on a lattice starting from purely microscopic interactions. We visualize the simulated display calculating optical textures under crossed polarizers corresponding to the Monte Carlo microscopic configurations. We also investigate the orientational order and the molecular organizations in the different regions of the lattice, introducing and calculating suitable order parameters.
SPECTRAL PROPERTIES OF DERIVATIVE OPERATORS IN THE BASIS-SPLINE COLLOCATION METHOD
Authors: WELLS J.C. , OBERACKER V.E. , STRAYER M.R. , UMAR A.S.
Published: November 2004

We discuss the basis-spline collocation method for the lattice solution of boundary-value differential equations, drawing particular attention to the difference between lattice and continuous collocation methods. Spectral properties of the basis-spline lattice representation of the first and second spatial derivatives are studied for the case of periodic boundary conditions with homogeneous lattice spacing and compared to spectra obtained using traditional finite-difference schemes. Basis-spline representations are shown to give excellent resolution on small-length scales and to satisfy the chain rule with good fidelity for the lattice-derivative operators using high-order splines. Application to the one-dimensional Dirac equation shows that very high-order spline representations of the Hamiltonian on odd lattices avoid the notorious spectral-doubling problem.
DESIGN AND SIMULATION OF THE ON-LINE TRIGGER AND RECONSTRUCTION FARM FOR THE HERA-B EXPERIMENT
Authors: LEGRAND I.C. , GENSCH U. , LEICH H. , WEGNER P.
Published: November 2004

The common third level trigger and forth level reconstruction farm for the future HERA-B experiment will have to perform full on-line event reconstruction and calibration for an expected input rate of 2000 events/s. More than a hundred powerful RISC processors connected in a network capable of distributing several hundreds of MB/s with low latency are likely to be necessary for this task.

Proper simulation of the real time multi-processor systems is central for an optimal design (hardware and software protocol) of a scalable and flexible parallel data processing architecture. A discrete event, process oriented simulation developed in concurrent μC++ is used as a framework for modelling and evaluating different farm architectures. An object oriented graphic interface to the simulation allows the monitoring of various features and provides an easier way to optimize the system.
THE CALCULATION OF VARIOUS QUANTITIES WITHIN PERTURBATION THEORY AT THE 3- AND 4-LOOP ORDER
Authors: VAN RITBERGEN T. , VERMASEREN J.A.M. , LARIN S.A. , NOGUEIRA P.
Published: November 2004

We discuss methods and techniques that were recently used in the following high order perturbative calculations: the large quark mass expansion of the decay rates Z0→ hadrons and τ→ν+ hadrons and the calculation of various quantities for deep inelastic lepton hadron scattering. Progress on the automatization of some general procedures is discussed.
Artificial Neural Networks as a Level-2 Trigger for the H1 Experiment: Status of the Hardware Implementation
Authors: Goldner D. , Getta H. , Kolander M. , Krämerkämper T. , Kolanoski H. , Fent J. , Fröchtenicht W. , Gaede F. , Gruber A. , Huber J. , Kiesling C. , Kobler T. , Köhne J. , Möck J. , Ribarics P. , Udluft S. , Westner D. , Zobel T.
Published: November 2004

Triggering at the HERA ep collider is challenging because of the high bunch crossing rate and an expected large background. In the H1 experiment, a trigger decision is made in four steps (level 1–4), stepwise decreasing the event rate and allowing for more sophisticated trigger decisions. The time available for L2 is about 20 μs. We have proposed to use an artificial neural network (ANN) for the L2 trigger based on the CNAPS-1064 chip available from Adaptive Solutions, (Oregon, USA). The intrinsic parallelism of the ANN algorithm together with the dedicated hardware offers fast processing of the trigger informations. The trigger system uses up to 10 decision units, each consisting of a Pattern Recognition Module (PRM) and a Data Distribution Board (DDB). A DDB receives the L2 data stream and generates the network inputs used by the algorithms on the PRM. A PRM is a commercial VME board carrying the CNAPS processors.
PARTICLE SEARCHES WITH NEURAL NETS
Authors: STIMPFL-ABELE GEORG
Published: November 2004

The efficiency and robustness of neural feed-forward nets in particle searches is studied using the search for the Standard Higgs Boson at LEP-200 as an example. Methods to select the most efficient variables, to define standard cuts, and to recognize significant differences between the training-data sample and a test-data sample are presented. The efficiencies of the neural nets are significantly better than those of standard methods.
DETERMINING DEPENDENCY STRUCTURES AND ESTIMATING NONLINEAR REGRESSION ERRORS WITHOUT DOING REGRESSION
Authors: PETERSON CARSTEN
Published: November 2004

A general method is discussed, the δ-test, which establishes functional dependencies given a table of measurements. The approach is based on calculating conditional probabilities from data densities. Imposing the requirement of continuity of the underlying function the obtained values of the conditional probabilities carry information on the variable dependencies. The power of the method is illustrated on synthetic time-series with different time-lag dependencies and noise levels. For N data points the computational demand is N2. Also, the same method is used for estimating nonlinear regression errors and their distributions without performing regression. Comparing the predicted residual errors with those from linear models provides a signal for nonlinearity. The virtue of the method in the context of feedforward neural networks is stressed with respect to preprocessing data and tracking residual errors.
GIOTTO: A CODE FOR THE NONLINEAR ANALYSIS OF AREA-PRESERVING MAPPINGS
Authors: SERVIZI G. , BORTOLOTTI D. , TODESCO E. , GIOVANNOZZI M. , VRAHATIS M. N.
Published: November 2004

An interactive code for the analysis of nonlinear area-preserving mappings is described; several facilities allow the user to draw phase portraits, make zooming, and use colors. The perturbative approach of normal forms and all the standard tools for the analysis of the nonlinear dynamics (Fourier spectra, Lyapunov exponents, fixed points …) are implemented in a user-friendly graphic environment based on X-window and OSF-Motif. Both simple models and more involved mappings which describe the betatronic motion in a particle accelerator can be implemented.
PROJECTION MONTE CARLO METHODS: AN ALGORITHMIC ANALYSIS
Authors: CERF NICOLAS J. , MARTIN OLIVIER C.
Published: November 2004

Projection methods such as Green's function and diffusion Monte Carlo are commonly used to calculate the leading eigenvalue and eigenvector of operators or large matrices. They thereby give access to ground state properties of quantum systems, and finite temperature properties of classical statistical mechanical systems having a transfer matrix. The basis of these approaches is a stochastic application of the power method in which a "projection" operator is applied iteratively. For the systematic errors to be small, the number of iterations must be large; however, in that limit, the statistical errors grow tremendously. We present an analytical study of the main variance reduction methods used for dealing with this problem. In particular, we discuss the consequences of guiding, replication, and population control on statistical and systematic errors.
SPHERICALLY SYMMETRIC THICK BRANES IN VACUUM
Authors: BORHANI MASSOUD , MANSOURI REZA , KHAKSHOURNIA SAMAD
Published: November 2004

We consider a spherical thick 3-brane immersed in a five-dimensional bulk space–time. We demonstrate how the thick brane equation of motion expanded in powers of the thickness of the brane can be obtained from the expected junction conditions on the boundaries of thick brane with the two embedding space–times. It is shown that the finite thickness corrections lead to a faster collapse of the brane in the vacuum.
DERIVATION OF AN INFINITE CLASS OF FIVE-DIMENSIONAL CONFORMALLY FLAT t-, r- AND x5-DEPENDENT COSMOLOGICAL METRICS
Authors: WATTS DAVID G.
Published: November 2004

Solutions to an infinite class of conformally flat 5D GR metrics are here derived. Since the standard 4D cosmological models (FRW solutions) can be embedded within a flat 5D manifold, such solutions may, then, be of cosmological interest. However, such conformally flat solutions have previously been derived dependent on t and ronly; independent of x5. To be able to further examine the results of such a 5D embedding, a more general solution should also depend on x5. Such solutions (5D conformally flat, dependent on t, r and x5) are here derived. An additional property of such solutions is that they turn out to be Riemann flat; that also is discussed.