bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the RET,GDNF, EDN3, andEDNRB genes in patients with intestinal neuronal dysplasia and Hirschsprung disease
Authors: Gath R , Goessling A , Keller K-M , Koletzko S , Coerdt W , Müntefering H , Wirth S , Hofstra R M W , Mulligan L , Eng C , von Deimling A
Published: July 2002

BACKGROUND

Hirschsprung disease (HSCR) is a frequent congenital disorder with an incidence of 1 in 5000 live births, characterised by the absence of parasympathetic intramural ganglion cells in the hindgut resulting in intestinal obstruction in neonates and severe constipation in infants and adults. Intestinal neuronal dysplasia (IND) shares clinical features with HSCR but the submucosal parasympathetic plexus is affected. IND has been proposed as one of the most frequent causes of chronic constipation and is often associated with HSCR.

METHODS

We examined 29 patients diagnosed with sporadic HSCR, 20 patients with IND, and 12 patients with mixed HSCR/IND for mutations in the coding regions of theRET, GDNF,EDNRB, and EDN3genes. The entire coding regions were analysed by single strand conformational polymorphism and DNA sequencing.

RESULTS

Only threeRET mutations were detected in patients with HSCR. In patients with IND or a mixed HSCR/IND phenotype, no mutations in these genes were observed. While HSCR and HSCR/IND showed over representation of a specific RET polymorphism in exon 2, IND exhibited a significantly lower frequency comparable with that of controls.

CONCLUSIONS

The mutation frequency found in our sporadic HSCR patients (10%) and the allelic distribution of RET polymorphisms are comparable with earlier published data. A significantly different allelic distribution in an established HSCR associated polymorphism argues against common genetic pathways for HSCR and IND.
Hyperkalaemic quadriparesis secondary to chronic diclofenac treatment
Authors: Patel P , Mandal B , Greenway M W
Published: July 2002

A 76 year old woman presented with a quadriparesis associated with hyperkalaemia. She had a 10 month history of treatment with oral diclofenac sodium. On admission she had hyperkalaemic metabolic acidosis with a normal anion gap and mild renal impairment. Her weakness resolved after withdrawal of diclofenac and medical correction of her hyperkalaemia. Non-steroidal anti-inflammatory drugs are known to cause hyperkalaemic acidosis and should be used with caution, especially in the presence of renal impairment.
MEN-2A syndrome and pulmonary metastasis
Authors: Alfaro J J , Lamas C , Estrada J , Lucas T
Published: July 2002

A case of multiple endocrine neoplasia syndrome type-2A (MEN-2A) with primary hyperparathyroidism and medullary carcinoma of thyroid initially treated by surgery is reported. The presence of pulmonary nodules six years after the initial treatment was thought to be related to metastasis of medullary carcinoma, and the increase in serum calcium concentrations was assumed to be caused by persistence of parathyroid adenomatous or hyperplastic tissue. The patient underwent surgery again and the pulmonary nodules were confirmed to be metastases of a parathyroid carcinoma, a very rare entity in MEN-2A syndrome.
Compression tests on a slurry using a small-scale consolidometer
Authors: Bo M W , Choa V , Wong K S
Published: July 2002

To understand the deformation of ultrasoft soil in a viscous state, compression tests were carried out using a small-scale consolidometer equipped with pore-pressure transducers at three locations. Deformation behavior was monitored with both settlement and pore-pressure measurements. The transitional points from slurry to soil were determined from the settlement rate, change in void ratio, change in permeability, and pore-pressure dissipation. It was found that the transitional void ratio determined from the settlement rate is smaller than that determined from the commencement of pore-pressure dissipation. The transitional void ratio varied slightly for samples with different initial moisture contents determined based on pore-pressure considerations. The variation was due to the difference in sample thickness which affected the initiation of pore-pressure dissipation at the bottom of sample. In reality, the void ratio at transition could be larger than those determined from both settlement and pore pressure.Key words: ultrasoft soil, deformation, compression, pore pressure, permeability.
Residues and Topological Yang–Mills Theory in Two Dimensions
Authors: Mohri Kenji
Published: July 2002

A residue formula which evaluates any correlation function of topological SUn Yang–Mills theory with arbitrary magnetic flux insertion in two-dimensions are obtained. Deformations of the system by two-form operators are investigated in some detail. The method of the diagonalization of a matrix-valued field turns out to be useful to compute various physical quantities. As an application we find the operator that contracts a handle of a Riemann surface and a genus recursion relation.
Spectral Analysis of N-Body Systems Coupled to a Bosonic Field
Authors: Skibsted Erik
Published: July 2002

We develop an extension of the abstract Mourre theory which consecutively is used to prove spectral properties of various systems coupled to a massless bosonic field. Our models include the spin-boson model and the standard model of quantum electrodynamics for a non-relativistic atom considered recently in [8] and [3] respectively.
KNOWLEDGE-BASED OR KNOWER-BASED?
Authors: EICKEMEYER MABEL WAI LIN
Published: July 2002

This paper analyses the concept of a knowledge-based society. It suggests that certain important features of a knowledge-based society are better understood by appealing to the notion of a knower-based society, and discusses some implications following from this. One point highlighted is that the existence of a knowledge-based society would exert pressure on the need to define the ethical challenges of such a society. It is proposed that some of the most pressing issues in the knowledge-based era, such as those revolving around the production and dissemination of knowledge, actually go hand-in-hand with questions of value.
POSITRONIUM DECAY: GAUGE INVARIANCE AND ANALYTICITY
Authors: PESTIEAU J. , SMITH C. , TRINE S.
Published: July 2002

The construction of positronium decay amplitudes is handled through the use of dispersion relations. In this way, emphasis is put on basic QED principles: gauge invariance and soft-photon limits (analyticity).

A firm grounding is given to the factorization approaches, and some ambiguities in the spin and energy structures of the positronium wave function are removed. Nonfactorizable amplitudes are naturally introduced. Their dynamics are described, especially regarding the enforcement of gauge invariance and analyticity through delicate interferences. The important question of the completeness of the present theoretical predictions for the decay rates is then addressed. Indeed, some of those nonfactorizable contributions are unaccounted for by NRQED analyses. However, it is shown that such new contributions are highly suppressed, being of [Formula: see text].

Finally, a particular effective form factor formalism is constructed for parapositronium, allowing a thorough analysis of binding energy effects and analyticity implementation.
THERMODYNAMIC PROPERTIES OF A MIXED SPIN-1/2 AND SPIN-1 MAGNETIC SUPERLATTICE
Authors: SARMENTO ENALDO F. , CRESSONI JOSÉ C. , DOS SANTOS ROBERTO J. V.
Published: July 2002

One considers a magnetic superlattice formed by mixed spin-1/2 and spin-1 alternate monolayers of ferromagnetic materials linked ferromagnetically with one another. Each monolayer is modelled by a simple quartic lattice of spins coupled via nearest-neighbor exchange (Ising ferromagnetic) with a single-ion anisotropy D acting in the spin-1 sites. An effective-field theory that accounts for self-spin correlation is used to study the phase diagram and magnetization curves. It is found that the phase diagrams exhibit a number of interesting phenomena resulting from the dependence of the crystal field interaction. The magnetization and quadrupolar moment curves are also shown for a range of the interaction strengths and the anisotropy parameters.
A UNIFIED EXPLANATION FOR SUPERCONDUCTIVITY AND PSEUDOGAP IN YBa2Cu3O7-δ
Authors: LIU FU-SUI , PENG KUANG-DING , CHEN WAN-FANG
Published: July 2002

Taking the two-local-spin-mediated interaction (TLSMI) as pairing interaction, this paper explains six important experimental findings in YBa 2 Cu 3 O 7-δ (Y123), and makes some predictions. The main prediction is that there is very high temperature superconductivity in extra-underdoped Y123.
CONTROL OF THE ENERGY TRANSFER WITH THE OPTICAL MICROCAVITY
Authors: HOPMEIER M. , GUSS W. , DEUSSEN M. , GÖBEL E. O. , MAHRT R. F.
Published: July 2002

We present the first experimental observation that dipole-dipole interaction can be strongly enhanced by placing the system in a microcavity. We have studied the excitation energy transfer in poly(phenyl-p-phenylene vinylene) (PPPV) doped with DCM molecules, placed within a Fabry-Perot resonator. As the spectral position of the cavity resonant mode in tuned across the DCM absorption profile, the transfer efficiency from PPPV to DCM changes dramatically as revealed by photoluminescence (PL) spectra. This behavior is clear evidence for the increase of the dipole-dipole interaction strength at the cavity resonances mediated by propagating modes emitted from the excited dipoles.
INVESTIGATION ON OPTICAL EMISSION SPECTRA DURING ECR PLASMA ENHANCED MAGNETRON SPUTTERING CARBON NITRIDE FILM DEPOSITION
Authors: Xu Jun , Ma Tengcai , Zhang Jialiang , Deng Xinlu , Zhang Wenfang , Perrone Alessio
Published: July 2002

Emission spectra from the ECR plasma enhanced magnetron sputtering discharge used for CNx film deposition were investigated in the wavelength range 350 – 550 nm. The optical emission spectra from both the negative glow discharge zone near the target surface and the plasma zone formed by ECR discharge and magnetron discharge were studied separately. The dominant chemical species in both zone were found to be N2+, N2* , and CN radicals. But the intensity of CN radical in the plasma zone was greater than that in the negative zone, where an emission band of C2 was detected. The dependence of the intensities of CN band on the working gas pressure was investigated, and the formation of CN radicals, which could be vital in the CNx film deposition process, was discussed. It was shown that a possible mechanism could be the reaction of N2+ and N 2 with C 2 in the gas phase.
HAPPER'S CURIOUS DEGENERACIES AND YANGIAN
Authors: BAI CHENG-MING , GE MO-LIN , XUE KANG
Published: July 2002

We find raising and lowering operators distinguishing the degenerate states for the Hamiltonian [Formula: see text] at x = ± 1 for spin 1 that was given by Happer et al.1,2 to interpret the curious degeneracies of the Zeeman effect for condensed vapor of 87 Rb . The operators obey Yangian commutation relations. We show that the curious degeneracies seem to verify the Yangian algebraic structure for quantum tensor space and are consistent with the representation theory of Y(sl(2)).
FUSION CONSTRUCTION OF THE VERTEX OPERATORS IN HIGHER LEVEL REPRESENTATION OF THE ELLIPTIC QUANTUM GROUP
Authors: KONNO HITOSHI
Published: July 2002

After a short summary on the elliptic quantum group [Formula: see text] and the elliptic algebra [Formula: see text], we present a free field representation of the Drinfeld currents and the vertex operators (VO's) in the level k. We especially demonstrate a construction of the higher spin type I VO's by fusing the spin 1/2 type I VO's and fix a rule of attaching the screening current S(z) associated with the q-deformed ℤk-parafermion theory. As a result we get a free field representation of the higher spin type I VO's which commutation relation by the fused Boltzmann weight coefficients is manifest.
Single and Double Side YBCO Thin Films for X-Band Microwave Filters and Devices
Authors: Beneduce C. , Bobba F. , Boffa M. , Cucolo A. M. , Cucolo M. C. , Andreone A. , Aruta C. , Iavarone M. , Palomba F. , Pica G. , Salluzzo M. , Vaglio R.
Published: July 2002

The properties of high quality single side and double side YBa 2 Cu 2 O 7-δ (YBCO) thin films deposited on LaA1O 3 substrates by pure oxygen d.c. sputtering are reported. The single side films are highly c -axis oriented with their a (or b) axis parallel to that of the substrate. The critical temperature is higher than 91 K with transition width less than 0.5 K, while the critical current density Jc is higher than 3 MA/cm2 at 77 K. The best double side samples exhibit no appreciable differences in the superconducting properties of the films deposited on the two different sides. X-ray analyses show in both cases highly c-axis oriented thin films with comparable values of the c -axis length (1.169 nm). The microwave properties are tested by a microstrip resonator technique. The surface resistance is lower than 80 μΩ at 77 K and f=5.4 GHz while the penetration depth at low temperature is in the range 150-200 nm.
SMALL ANGLE GRAIN BOUNDARY IN YBa2Cu3Oy SUPERCONDUCTOR
Authors: CHEN WU MING , HUANG J. W. , JIANG S. S. , GUO Y. C. , LIU H. K. , DOU S. X.
Published: July 2002

Electron diffraction spots splitting into three is an unusual phenomenon. Based on the analysis of crystal structure, the splitting is believed due to some neighboring crystal cells grow along a small angle θ, rather than along a parallel direction as in general case. When a crystal grows along two neighboring boundaries with a small angle, the distance of the two boundaries increases as well. When the distance of the two boundaries reaches as large as a cell constant, a new cell will grow in the site, which is called an edge dislocation. According to the geometric relation of the reciprocal space, small angle grain boundaries can be calculated from the corresponding splitting spots. In this work, two small angles θ are determined to be -2.5° and 3.0°, respectively. Obviously, the grain with small angle grain boundaries has a curved surface and the curvature of the surface is determined by the density of the edge dislocation. The corresponding parameters of the edge dislocation are calculated. Both the edge dislocation and the neighboring cells growing along a small angle are a growing mechanism of YBa 2 Cu 3 O y and this mechanism is responsible for the curved grain surface.
NON-EXPONENTIALLY LOCALIZED STATES IN A TWO-DIMENSIONAL DISORDERED SYSTEM?
Authors: GODA MASAKI , AZBEL MARK YA. , YAMADA HIROAKI
Published: July 2002

We study the length L dependence of the forward component of the transfer matrix for an electron passing through a strip with δ-function impurity potentials, with particular attention to the slowest growth-rate characteristic. In the first step of our microscopic study we obtain the inverse localization length for low energy electron in a weakly perturbed system. We show by considering an ensemble averaged mixed tensor a critical energy dividing exponential localization and non-exponential localization in the two-dimensional disordered system.
Boundary conditions of electron at Interface to ductility of superconductor
Authors: Cheng Shuyu
Published: July 2002

Recent years, Prof. Cheng Kaijia raised and developed a new electron theory based on the first principles, which is called as TFDC by researchers in China. The theory clearly exponnds the important role of boundary conditions of electron. It has been successfully applied and some valuable results have been obtained, which are in agreement with the experiments.
NANOSCOPIC PHASE SEPARATION AND THE UNIVERSAL TRANSPORT AND MAGNETIC PROPERTIES OF HIGH Tc SUPERCONDUCTORS
Authors: JUNG J. , YAN H. , DARHMAOUI H. , ABDELHADI M.
Published: July 2002

We have found the correlation between nanoscopic phase separation in the copper-oxygen planes of YBCO and TlBCCO and the transport and magnetic properties of these materials in the a-b planes such as: the temperature dependence of the critical current density Jc( T ), the temperature dependence of the superfluid density ns( T )∝1/λ2( T ) at low temperatures, the temperature dependence of the normalized logarithmic relaxation rate S(T), and the dependence of the effective energy barrier against vortex motion on the current density Ueff( J ). These properties are controlled by the ratio of the amount of an underdoped filamentary phase to that of an optimally doped one.
IRON OXIDATION STATES AND DISTRIBUTION IN THE 4Bi2O3· PbO GLASS MATRIX
Authors: SIMON V. , POP R. , NEUMANN M. , CHIUZBAIAN S. G. , COLDEA M. , SIMON S.
Published: July 2002

Magnetic susceptibility and XPS results on x Fe 2O3 · (100-x) [4 Bi 2O3 · PbO] where 0<x ≤20 samples are presented in order to point out the oxidation states and the distribution of iron ions in the lead-bismuthate matrix. The valence state of iron ions changes from Fe3+ to Fe2+ as the Fe2O3 content increases from 1 to 20 mol%. The XPS data indicate the migration of metallic elements in the inner part of the bulk investigated samples.
Instability and Periodic Deformation in Bilayer Membranes Induced by Freezing
Authors: Jie Yan , Haijun Zhou , Zhong-Can Ou-Yang
Published: July 2002

The instability and periodic deformation of bilayer membranes during freezing processes are studied as a function of the difference of the shape energy between the high and the low temperature membrane states. It is shown that there exists a threshold stability condition, below which a planar configuration will be deformed. Among the deformed shapes, the periodic curved square textures are shown to be a class of the solutions of the associated shape equation. In consistency with recent experimental observations, the optimal ratio of period and amplitude for such a texture is found to be approximately equal to [Formula: see text].
LASER-STIMULATED DOPING OF SILICON WITH MAGNESIUM
Authors: AROUTIOUNIAN V. M. , HAKHOYAN A. P. , ADAMIAN Z. N. , BARSEGHIAN R. S.
Published: July 2002

The results of experiments involving the laser-stimulated doping of silicon with magnesium following thermal diffusion are presented. It has been shown that the Nd-laser irradiation (λ=1.06 μ m ) leads to the increase of the solubility and diffusion coefficient of magnesium in silicon. The current-voltage, capacity-voltage characteristics as well as the thermo-stimulated current spectra of doped samples have been investigated. The rectified behavior of the investigated structures is observed. It is shown that the laser irradiation leads to the formation of Mg centers with Ec-0.13 eV and Ec-0.28 eV energy levels.
GENERALIZED PARTITION FUNCTION FOR BOSE STATISTICS AND THERMODYNAMIC FUNCTIONS
Authors: FAN HONG-YI , ZOU HUI
Published: July 2002

Based on the density operator's coherent state representation [Phys. Lett.A252, 281 (1999)], we extend the well-known Bose distribution's partition function Ξ [Formula: see text] for ideal photon gas [Formula: see text] to that of an assembly of photon gas interacting with nonlinear medium described by the Hamiltonian [Formula: see text], where A=(a1,a2,…,an), Ω is a symmetric matrix, and we report that the corresponding partition function is [Formula: see text] As a result, the generalized Bose distribution and thermodynamic functions are derived.
HOMOCLINIC BIFURCATION OF MULTIHARMONIC PERTURBED SYSTEMS
Authors: WANG KE , TANG YUN
Published: July 2002

The dynamics of homoclinic tangencies for a multiharmonic perturbed system (MHPS) is studied. By applying the singularity theory to Melnikov function the normal forms at the homoclinic tangency points are obtained, and then the details of the homoclinic bifurcation are quite clear. An important result is that the behavior of homoclinic bifurcation for MHPS is strongly related to the number of harmonic components.
WAVE MIXING IN A BULK PHOTOREFRACTIVE MEDIUM: SPATIOTEMPORAL STRUCTURES AND AMPLITUDE EQUATIONS
Authors: SANDFUCHS O. , KAISER F. , BELIĆ M. R.
Published: July 2002

The counterpropagation of two laser beams through wave mixing in nonlinear optics may lead to spatiotemporal structures in the transverse beam profiles. We theoretically investigate the self-organization process of structures that arise in a photorefractive wave-mixing configuration with an external feedback mirror. The characteristic features mediated through the wave interaction in a bulk medium are discussed. Our group developed a beam propagation method that enabled us to perform numerical simulations beyond the first instability threshold. Primary and secondary spatiotemporal patterns, caused by the sluggish temporal response of the crystal in building reflection gratings, are observed. Analytically a Ginzburg–Landau equation for the order parameter and the corresponding longitudinal eigenfunctions of transverse modes, governing the propagation of the structures through the crystal, are derived and compared with our numerical results in one transverse dimension. First results of hexagonal patterns in two transverse dimensions are also presented.
ORBIT-PERIODS IN SECOND-ORDER FINITE-PRECISION DIGITAL FILTERS WITH OVERFLOW
Authors: CHAMBERS W. G.
Published: July 2002

The effect of n-bit precision on the orbit-periods of second-order lossless overflowing digital filters is discussed. It is observed that there are of the order of 2n orbits with periods O(2n), whereas in a random finite-state machine with the same number (2n)2 of states and with an invertible next-state function there are a few large orbits with periods O((2n)2). This behavior persists when the coefficient multiplication is replaced by a random mapping. This "randomized" model is readily understood and so provides a rough theory of the orbit-periods.
VIEWPOINTS ON MODIFIABILITY
Authors: LASSING NICO , RIJSENBRIJ DAAN , VAN VLIET HANS
Published: July 2002

Software architecture is generally regarded as an important tool to achieve systems of higher quality. It is claimed that the foundation for a system's quality is laid by the decisions made in the software architecture. A question that is occupying both researchers and practitioners is in which areas should decisions be made in the software architecture? We believe architectural view models play an important role in the answer to this question. View models consist of a coherent set of architectural views. These view models have both a prescriptive and a descriptive role in the development process. Their prescriptive role is that they call for a number of aspects to be considered when defining a software architecture and their descriptive role is that they provide a framework to document a software architecture. Currently, a number of view models exist, the most important of which are the 4+1 View Model of Kruchten and the four views by Soni et al.

In our experience with modifiability analysis for business information systems we found that the views in current view models do not include all information required. In this paper we discuss the views we found useful for architecture level impact analysis of business information systems. They are illustrated using a case study we performed for the Dutch Tax and Customs Administration. We claim that when these views are required for architecture level impact analysis, the decisions they capture should also be considered during architecture development.
GEOMETRIC EQUIVALENCE OF ALGEBRAS
Authors: BERZINS A.
Published: July 2002

In this paper, we study the geometric equivalence of algebras in several varieties of algebras. We solve some of the problems formulated in [2], in particular, that of geometric equivalence for real-closed fields and finitely generated commutative groups.
A NOTE ON THE EXISTENTIAL THEORY OF EQUATIONS IN PLAIN GROUPS
Authors: DIEKERT VOLKER , LOHREY MARKUS
Published: July 2002

Based on a PSPACE-completeness result for free monoids with involution [4] it is shown that the existential theory of equations with rational constraints in plain groups is PSPACE-complete. As a corollary this settles a question from [16].
A FAMILY OF BRUNNIAN LINKS BASED ON EDWARDS' CONSTRUCTION OF VENN DIAGRAMS
Authors: MAES ARNAUD , CERF CORINNE
Published: July 2002

We construct an infinite family of brunnian links whose projections give the family of Venn diagrams for many sets constructed by Edwards.
MINIMISING THE BOUNDARIES OF PUNCTURED PROJECTIVE PLANES IN S3
Authors: DOMERGUE MICHEL , MATIGNON DANIEL
Published: July 2002

This paper concerns 3-manifolds X obtained by Dehn surgery on a knot in S 3, in particular those which contain embedded projective planes. Either, they are homeomorphic to the 3-real projeclive space ℝ P 3, or they are reducible.

Let p be the number of intersections of a projective plane in X with the core of the solid torus added during surgery. We prove here that either X is reducible or p is bigger than or equal to five.

Consequently, if X is homeomorphic to ℝ P 3 then all its projective planes are pierced at least in five points by the core of the surgery. This result is considered as a step towards showing that ℝ P 3 cannot be obtained by a Dehn surgery along a knot in S 3.
SURFACE DIAGRAMS OF TWIST-SPUN 2-KNOTS
Authors: SATOH SHIN
Published: July 2002

Given a tangle diagram of a classical knot K, we construct a surface diagram of any twist-spun 2-knot of K. From the crossings of the tangle diagram, we can get information of the corresponding triple points of the surface diagram, which are used to compute cocycle invariants of twist-spun 2-knots.
PLANCK-LENGTH PHENOMENOLOGY
Authors: AMELINO-CAMELIA GIOVANNI
Published: July 2002

This author's recent proposal of interferometric tests of Planck-scale-related properties of spacetime is here revisited from a strictly phenomenological viewpoint. The results announced previously are rederived using elementary dimensional considerations. The dimensional analysis is then extended to the other two classes of experiments (observations of neutral kaons at particle accelerators and observations of the gamma rays we detect from distant astrophysical sources) which have been recently considered as opportunities to explore "foamy" properties of spacetime. The emerging picture suggests that there is an objective and intuitive way to connect the sensitivities of these three experiments with the Planck length. While in previous studies the emphasis was always on some quantum-gravity scenario and the analysis was always primarily aimed at showing that the chosen scenario would leave a trace in a certain class of doable experiments, the analysis here reported takes as starting point the experiments and, by relating in a direct quantitative way the sensitivities to the Planck length, provides a model-independent description of the status of Planck-length phenomenology.
STATIC, MASSIVE FIELDS AND VACUUM POLARIZATION POTENTIAL IN RINDLER SPACE
Authors: LINET B.
Published: July 2002

In Rindler space, we determine in terms of special functions the expression of the static, massive scalar or vector field generated by a point source. We find also an explicit integral expression of the induced electrostatic potential resulting from the vacuum polarization due to an electric charge at rest in the Rindler coordinates. For a weak acceleration, we give then an approximate expression in the Fermi coordinates associated with the uniformly accelerated observer.
TYPE N PURE RADIATION FIELDS OF EMBEDDING CLASS ONE
Authors: LUDWIG GARRY
Published: July 2002

Type N pure radiation fields of embedding class one are re-investigated. A new class of solutions is obtained and a class of solutions, previously found by Collinson, is generalized.
A 2-D DESCRIPTION OF SOUND PROPAGATION IN A HORIZONTALLY-INHOMOGENEOUS OCEAN
Authors: GODIN OLEG A.
Published: July 2002

Effects of horizontal refraction on underwater sound propagation in deep and shallow water are considered within geometrical acoustics and adiabatic normal modes approximations. Several distinct formulations of the adiabatic approximation have been proposed in the literature on modal propagation. These formulations differ in the predicted values of mode amplitudes and, hence, in their reciprocity and energy-conserving properties. The formulations are compared with respect to their accuracy and domain of validity, assuming small and smooth variation of mode propagation constants characteristic of underwater acoustic waveguides. Perturbation theory for horizontal (modal) rays is used in the analysis. An approximate expression for the adiabatic mode amplitude in 3-D problems is derived which requires environmental information only along the source-receiver radial and which has greater accuracy than previous formulations. It is shown that the uncoupled azimuth approximation, also known as the N × 2-D approximation, overestimates travel times of ray arrivals as well as phases of adiabatic normal modes in a horizontally-inhomogeneous ocean. The travel time and phase biases rapidly increase with the value of cross-range environmental gradients and propagation range. Simple and explicit expressions for leading-order corrections to the travel time and the phase are found in terms of path-averaged cross-range environmental gradients. Implications on applicability of the uncoupled azimuth approximation for sound propagation modeling in a horizontally-inhomogeneous ocean are discussed. A perfect-wedge model of the coastal ocean is chosen to illustrate the importance of the travel-time and phase biases due to horizontal refraction.
CRYSTAL GROWTH AND SURFACE ANISOTROPY IN MICROHARDNESS OF ZINC (TRIS) THIOUREA SULPHATE, AN NLO CRYSTAL
Authors: DESAI C. F. , GUPTE SONAL
Published: July 2002

ZTS crystals have been grown by the solution method. The usual habit of the crystals has been identified and dislocation etching on the three major habit planes, (100), (010) and (001), has been carried out. The Vickers microhardness of these planes, its applied load dependence and anisotropy have been studied. (100) has been found to be the hardest of the three planes. The surface anisotropy of hardness of the respective planes has been explored and the hard and soft directions have been identified.
ADDIMER DIFFUSIION ON THE Si(100) SURFACE
Authors: LEE GUN-DO , WANG C. Z. , LU Z. Y. , HO K. M.
Published: July 2002

Diffusion of silicon addimer along the trough and from the trough to the top of dimer row on the Si(100) surface are investigated by tight-binding molecular dynamics calculations using the environment-dependent tight-binding silicon potential and by ab initio calculations using the Car–Parrinello method. The studies discover new diffusion pathways consisting of rotation of addimer. These new pathways have energy barriers in excellent agreement with experiment data and are more energetically favorable than other diffusion pathways studied previously.
COMBINED SECOND AND THIRD TOE TRANSFER: CURRENT PRACTICE
Authors: El-Gammal Tarek Abdalla , Wei Fu-Chan
Published: July 2002

A ten-year experience of combined second and third toe transfer is described. The length, position, and the web space are important considerations during planning. To preserve bone and skin for the donor foot, these tissues should be reconstructed with groin flap and bone block beforehand. During operation, special attention should be paid to the exact design of incision, retrograde dissection of the metatarsal artery, tight extensor repair and longitudinal K-wire, to prevent clawing and wound closure before vascular anastomosis. Passive mobilization and sensory re-education should begin early.
LEARNING OTHER AGENTS' PREFERENCES IN MULTI-AGENT NEGOTIATION USING THE BAYESIAN CLASSIFIER
Authors: BUI H. H. , VENKATESH S. , KIERONSKA D.
Published: July 2002

In multi-agent systems, most of the time, an agent does not have complete information about the preferences and decision making processes of other agents. This prevents even the cooperative agents from making coordinated choices, purely due to their ignorance of what other want. To overcome this problem, traditional coordination methods rely heavily on inter-agent communication, and thus become very inefficient when communication is costly or simply not desirable (e.g. to preserve privacy). In this paper, we propose the use of learning to complement communication in acquiring knowledge about other agents. We augment the communication-intensive negotiating agent architecture with a learning module, implemented as a Bayesian classifier. This allows our agents to incrementally update models of other agents' preferences from past negotiations with them. Based on these models, the agents can make sound predictions about others' preferences, thus reducing the need for communication in their future interactions.
Stock Market Reactions to Bank Industry Restructuring: The Korean Experience of 1997 and 1998
Authors: Kang Jong Man , Kim Youngkap , Yi Myung Chul , Chambers Donald R.
Published: July 2002

This paper examines some of the effects on shareholder wealth of the Korean bank restructuring measures that followed the Korean IMF bailout. The Korean banks are divided into four groups to check for differences in market reactions to FSC restructuring mandates. We find that shareholders of healthy banks benefit when self-rescue or management improvement measures are implemented at distressed banks. Share prices of banks not directly involved in the restructuring process are not significantly influenced by the restructuring. However, shareholders of financially distressed banks suffered significant losses, as much as they would have incurred had the bank closed. Share prices of banks ordered to improve management were influenced as much as share prices of closed banks. We therefore conclude that financially weak banks were significantly affected by restructuring orders, while comparatively sound banks were not significantly influenced.
Intelligent software technology for the new decade
Authors: Narin'yani Alexander S.
Published: July 2002

Our collective has been working in the Al domain for more than 15 years. During most of that period our research focused on two “classical” subjects: 1. natural language interfaces and 2. knowledge representation and processing. From the early 1980s, in addition to working on the conceptual aspects of Al, we have been increasingly involved in developing advanced technology of intelligent systems. Participating in the START project [1] stimulated our research and development [R&D] in this direction. Our task in the project was to design a more elaborate version of an industrial-type technology based on pilot software “factories.” These would allow a multiple—10-fold and more—increase in the efficiency
Revisiting computer security in the business world
Authors: Wilkes Maurice V.
Published: July 2002

In my first column (
Communications,
Apr. 1990) I discussed computer security in the business world. I remarked that whereas the military had always attached great importance to security, business managers regarded it as yet another demand on their budgets, and have required convincing about its importance. As a result, the military made most of the advances in research on computer security for a long time. They have evolved what is now a well-developed doctrine.
From under the rubble
Authors: Goodman Seymour E.
Published: July 2002

How does an entire country return to life?

The dictatorship of Nicolae and Elena Ceaucescu turned Romania into a political, social and economic wasteland that was vividly pictured in the world media after the overthrow of the Stalinist couple in December 1989. Their regime left the country in shambles: with an old or mangled physical plant, a currency worthless abroad and nearly worthless at home, a legacy of secret police abuses, terrible health and sanitary conditions, and a highly centralized, warped, and inefficient scientific and industrial infrastructure.
Double-step incremental linear interpolation
Authors: Rokne J. , Rao Y.
Published: July 2002

A two-step incremental linear interpolation algorithm is derived and analyzed. It is shown that the algorithm is correct, that it is reversible, and that it is faster than previous single-step algorithms. An example is given of the execution of the algorithm.
Algorithm 716: TSPACK: tension spline curve-fitting package
Authors: Renka R. J.
Published: July 2002

The primary purpose of TSPACK is to construct a smooth function which interpolates a discrete set of data points. The function may be required to have either one or two continuous derivatives. If the accuracy of the data does not warrant interpolation, a smoothing function (which does not pass through the data points) may be constructed instead. The fitting method is designed to avoid extraneous inflection points (associated with rapidly varying data values) and preserve local shape properties of the data (monotonicity and convexity), or to satisfy the more general constraints of bounds on function values or first derivatives. The package also provides a parametric representation for construction general planar curves and space curves.
Optimal disk allocation for partial match queries
Authors: Abdel-Ghaffar Khaled A. S. , El Abbadi Amr
Published: July 2002

The problem of disk allocation addresses the issue of how to distribute a file on several disks in order to maximize concurrent disk accesses in response to a partial match query. In this paper a coding-theoretic analysis of this problem is presented, and both necessary and sufficient conditions for the existence of strictly optimal allocation methods are provided. Based on a class of optimal codes, known as maximum distance separable codes, strictly optimal allocation methods are constructed. Using the necessary conditions proved, we argue that the standard definition of strict optimality is too strong and cannot be attained, in general. Hence, we reconsider the definition of optimality. Instead of basing it on an abstract definition that may not be attainable, we propose a new definition based on the best possible allocation method. Using coding theory, allocation methods that are optimal according to our proposed criterion are developed.
The evaluation of text editors: methodology and empirical results.
Authors: Roberts Teresa L. , Moran Thomas P.
Published: July 2002

This paper presents a methodology for evaluating text editors on several dimensions: the time it takes experts to perform basic editing tasks, the time experts spend making and correcting errors, the rate at which novices learn to perform basic editing tasks, and the functionality of editors over more complex tasks. Time, errors, and learning are measured experimentally; functionality is measured analytically; time is also calculated analytically. The methodology has thus far been used to evaluate nine diverse text editors, producing an initial database of performance results. The database is used to tell us not only about the editors but also about the users—the magnitude of individual differences and the factors affecting novice learning.
Confluence properties of weak and strong calculi of explicit substitutions
Authors: Curien Pierre-Louis , Hardin Thérèse , Lévy Jean-Jacques
Published: July 2002

Categorical combinators [Curien 1986/1993; Hardin 1989; Yokouchi 1989] and more recently λσ-calculus [Abadi 1991; Hardin and Le´vy 1989], have been introduced to provide an explicit treatment of substitutions in the λ-calculus. We reintroduce here the ingredients of these calculi in a self-contained and stepwise way, with a special emphasis on confluence properties. The main new results of the paper with respect to Curien [1986/1993], Hardin [1989], Abadi [1991], and Hardin and Le´vy [1989] are the following:

(1) We present a confluent weak calculus of substitutions, where no variable clashes can be feared;
(2) We solve a conjecture raised in Abadi [1991]: λσ-calculus is not confluent (it is confluent on ground terms only).

This unfortunate result is “repaired” by presenting a confluent version of λσ-calculus, named the λ
Env
-caldulus in Hardin and Le´vy [1989], called here the confluent λσ-calculus.
Natural-language retrieval of images based on descriptive captions
Authors: Guglielmo Eugene J. , Rowe Neil C.
Published: July 2002

We describe a prototype intelligent information retrieval system that uses natural-language understanding to efficiently locate captioned data. Multimedia data generally require captions to explain their features and significance. Such descriptive captions often rely on long nominal compounds (strings of consecutive nouns) which create problems of disambiguating word sence. In our system, captions and user queries are parsed and interpreted to produce a logical form using a detailed theory of the meaning of nominal compounds. A
fine-grain
match can then compare the logical form of the query to the logical forms for each caption. To improve system efficiency, we first perform a
coarse-grain
match with index files, using nouns and verbs extracted from the query. Our experiments with randomly selected queries and captions from an existing image library show an increase of 30% in precision and 50% in recall over the keyphrase approach currently used. Our processing times have a median of seven seconds as compared to eight minutes for the existing system, and our system is much easier to use.
Context constraints for compositional reachability analysis
Authors: Cheung Shing Chi , Kramer Jeff
Published: July 2002

Behavior analysis of complex distributed systems has led to the search for enhanced reachability analysis techniques which support modularity and which control the state explosion problem. While modularity has been achieved, state explosion in still a problem. Indeed, this problem may even be exacerbated, as a locally minimized subsystem may contain many states and transitions forbidden by its environment or context. Context constraints, specified as interface processes, are restrictions imposed by the environment on subsystem behavior. Recent research has suggested that the state explosion problem can be effectively controlled if context constraints are incorporated in compositional reachability analysis (CRA). Although theoretically very promising, the approach has rarely been used in practice because it generally requires a more complex computational model and does not contain a mechanism to derive context constraints automatically. This article presents a technique to automate the approach while using a similar computational model to that of CRA. Context constraints are derived automatically, based on a set of sufficient conditions for these constraints to be transparently included when building reachability graphs. As a result, the global reachability graph generated using the derived constraints is shown to be observationally equivalent to that generated by CRA without the inclusion of context constraints. Constraints can also be specified explicitly by users, based on their application knowledge. Erroneous constraints which contravene transparency can be identified together with an indication of the error sources. User-specified constraints can be combined with those generated automatically. The technique is illustrated using a clients/server system and other examples.
Scheduler-conscious synchronization
Authors: Kontothanassis Leonidas I. , Wisniewski Robert W. , Scott Michael L.
Published: July 2002

Efficient synchronization is important for achieving good performance in parallel programs, especially on large-scale multiprocessors. Most synchronization algorithms have been designed to run on a dedicated machine, with one application process per processor, and can suffer serious performance degradation in the presence of multiprogramming. Problems arise when running processes block or, worse, busy-wait for action on the part of a process that the scheduler has chosen not to run. We show that these problems are particularly severe for scalable synchronization algorithms based on distributed data structures. We then describe and evaluate a set of algorithms that perform well in the presence of multiprogramming while maintaining good performance on dedicated machines. We consider both large and small machines, with a particular focus on scalability, and examine mutual-exclusion locks, reader-writer locks, and barriers. Our algorithms vary in the degree of support required from the kernel scheduler. We find that while it is possible to avoid pathological performance problems using previously proposed kernel mechanisms, a modest additional widening of the kernel/user interface can make scheduler-conscious synchronization algorithms significantly simpler and faster, with performance on dedicated machines comparable to that of scheduler-oblivious algorithms.
Computer Time for Address Calculation Sorting
Authors: Flores Ivan
Published: July 2002

For each item to be sorted by address calculation, a location in the file is determined by a linear formula. It is placed there if the location is empty. If there is an item at the specified location, a search is made to find the closest empty space to this spot. The item at the specified location, together with adjacent items, is moved by a process similar to musical chairs, so that the item to be filed can be entered in its proper order in the file. A generalized flowchart for computer address calculation sorting is presented here. A mathematical analysis using average expectation follows. Formulas are derived to determine the number of computer operations required. Further formulas are derived which determine the time required for an address calculation sort in terms of specific computer orders. Several examples are given. A sorting problem solved elsewhere in the literature by an empirical method is solved by the formulas developed here to demonstrate their practical application.
Upper Bounds for the Total Path Length of Binary Trees
Authors: Wong C. K. , Nievergelt J.
Published: July 2002

Two upper bounds for the total path length of binary trees are obtained. One is for node-trees, and bounds the internal (or root-to-node) path length; the other is for leaf-trees, and bounds the external (or root-to-leaf) path length. These bounds involve a quantity called the balance, which allows the bounds to adapt from the
n
log
n
behavior of a completely balanced tree to the
n
2
behavior of a most skewed tree. These bounds are illustrated for the case of Fibonacci trees.
Application of the Diffusion Approximation to Queueing Networks II: Nonequilibrium Distributions and Applications to Computer Modeling
Authors: Kobayashi Hisashi
Published: July 2002

Quite often explicit information about the behavior of a queue over a fairly short period is wanted. This requires solving the nonequilibrium solution of the queue-length distribution, which is usually quite difficult mathematically. The first half of Part II shows how the diffusion process approximation can be used to answer this question. A transient solution is obtained for a cyclic queueing model using the technique of eigenfunction expansion. The second half of Part II applies the earlier results of Part I to modeling and performance problems of a typical multiprogrammed computer system. Such performance measures as utilization, throughput, response time and its distribution, etc., are discussed in some detail.
A note on the complexity of propositional Hoare logic
Authors: Cohen Ernie , Kozen Dexter
Published: July 2002

We provide a simpler alternative proof of the
PSPACE
-hardness of propositional Hoare logic (PHL).