bluuebunny/crossref_metadata_2025 huggingface dataset:
NUCLEAR RELAXATION IN IRREGULAR OR FRACTAL PORES
Authors: SAPOVAL B. , RUSS S. , KORB J. P. , PETIT D.
Published: May 2003

We apply a fractal description of pore surface irregularity to study the nuclear relaxation of a liquid confined in an irregular pore. Our calculation on a pre-fractal volume with infinite surface relaxation rate shows that the long time relaxation behavior is dominated by an exponential mode characterizing a free diffusive volume. At short time, the calculated magnetization follows closely the power-law behavior previously proposed by de Gennes. For finite surface relaxation rate, we extend our studies of the efficiency of exchange on fractal membranes to nuclear relaxation in the same geometry. We predict a decay involving two characteristic times. For very slow surface relaxation, there will exist exponential relaxation governed by the surface relaxation. These laws show that the pore surface irregularities may play an important role in nuclear relaxation.
FRACTAL IMAGE ANALYSIS OF NATURAL SCENES AND MEDICAL IMAGES
Authors: SATO TAKASHI , MATSUOKA MAKOTO , TAKAYASU HIDEKI
Published: May 2003

We construct color map images of fractal dimension distribution from natural scenes and medical images by applying the box-counting method locally. The map images clearly show the difference between clouds and rocks, as well as between cancer parts and normal tissue in the colon. The method is simple and may be expected to be applicable to a real-time video-data processing.
SOLVING THE TWO-DIMENSIONAL INVERSE FRACTAL PROBLEM WITH THE WAVELET TRANSFORM
Authors: STRUZIK ZBIGNIEW R.
Published: May 2003

The methodology of the solution to the inverse fractal problem with the wavelet transform1,2 is extended to two-dimensional self-affine functions. Similar to the one-dimensional case, the two-dimensional wavelet maxima bifurcation representation used is derived from the continuous wavelet decomposition. It possesses translational and scale invariance necessary to reveal the invariance of the self-affine fractal. As many fractals are naturally defined on two-dimensions, this extension constitutes an important step towards solving the related inverse fractal problem for a variety of fractal types.
MULTIFRACTALITY OF SNOWFLAKES
Authors: WOLF MAREK
Published: May 2003

The results of the extensive numerical simulations of the Dielectric Breakdown Model (DBM) with noise reduction on the hexagonal lattice are presented. Seventy-five clusters grown under different boundary conditions consisting of 16 000 particles on the lattice 1001×1001 were generated. The simulations were done for the noise reduction parameter s equal to 200 and two values of the parameter η, namely for η=0.5 and 1. For the latter case, two boundary conditions were considered: the DBM and DLA b.c. Such a growth model leads to the formation of the fractal objects resembling real snowflakes. The growth probabilities were stored at the five stages of the clusters growth: at the masses of 1000, 2000, 4000, 8000 and 16 000 particles. Multifractal analysis was performed and obtained results are presented. The comparison of two methods: the histogram and moments methods, is provided. We discover that for the η=0.5 parameter, there is a phase transition, while for η=1, there appears to be no phase transition. Besides the usual growth probability measure, the measure given by the noise reduction counters is considered and multifractality of it is presented.
FRACTILES DERIVED FROM GENERALIZED DIGIT SYSTEMS
Authors: SONG H. J. , KANG B. S.
Published: May 2003

We introduce a general method of obtaining connected replicating fractiles based on generalized digit systems in the ring of Gaussian integers.
A FRACTAL BASED MODEL FOR THE CHARACTERIZATION OF THE INTERFACE IN TWO PHASE POLYCRYSTALLINE MATERIALS USING ACOUSTIC MEANS
Authors: DUTTA DEBASHREE , BARAT P. , MUKHERJEE P. , BANDYOPADHYAY S. K. , SEN PINTU , GANGULY S. N.
Published: May 2003

A model is proposed which investigates the structure of the interface separating two different phases in polycrystalline materials using acoustic waves. This model evaluates the expression for the intensity of the scattered acoustic waves in terms of the wave vector and correlates the observed intensity with the irregularities present on the interface. The concept of fractal dimension has been introduced to differentiate and characterize the irregularities of the interface.
ON MODELING ENVIRONMENTALLY-SENSITIVE GROWTH FORMS AND CELLULAR AUTOMATA USING MULTISET TRANSFORMATION
Authors: McEVOY HUGH , KAANDORP JAAP A.
Published: May 2003

We demonstrate the usefulness of multiset transformation for modeling growth processes which combine generational growth with environmental-sensitivity (such as photo-sensitivity and geometric constraints). Our examples are artificial structures with no immediate counterpart in physics and biology. However, our studies are intended to show the feasibility of multiset transformation for more realistic models. We show that multiset transformation is useful both as a formal and a computational model of growth processes.
PHOTOELASTIC STUDY ON THE MECHANICAL PROPERTIES OF FRACTAL ROCK JOINTS
Authors: XIE HEPING , XIE WEIHONG , ZHAO PENG
Published: May 2003

In this paper, the fractal rock joints are manufactured on the photoelastic material plate. Based on the visualized photoelastic experiments, the mechanical properties of the fractal joints with different roughness (different fractal dimensions) are investigated under uniaxial and shear compression. The research results indicate that the joint roughness (the fractal dimension of the joints) significantly influences the peak shear strength, the position of the maximum shear stress, and the number of contact points.
FRACTAL IMAGES OF GENERALIZED JULIA SETS
Authors: ONG KIM-KHOON , SHIAH AICHYUN , MUSIELAK ZDZISLAW E.
Published: May 2003

The iteration function [Formula: see text], where both α and β are positive real numbers, is used to generate families of the generalized Julia sets, [Formula: see text]. The calculations are restricted to the principal value of zα + iβ and the obtained results demonstrate that classical Julia sets, [Formula: see text] are significantly deformed when non-zero values of β are considered. As a result of this deformation, the area of stable regions in the complex plane changes and a process of splitting and shifting takes place along the real axis. It is shown that this process is responsible for the formation of new fractal images of generalized Julia sets.
LONG-TIME ASYMPTOTICS FOR DIFFUSING CLUSTERS WITH POISSON GROWTH STATISTICS
Authors: ŁUCZKA JERZY , RUDNICKI RYSZARD
Published: May 2003

Long-time asymptotics for the mean square displacement of diffusing fractal clusters, masses of which randomly grow according to the Poisson statistics, is proven to be a power function of time with the prefactor and exponent depending explicitly upon the fractal dimension of clusters.
CORRELATIONS OF PITCHES IN MUSIC
Authors: SHI YU
Published: May 2003

We investigate correlations among pitches in several songs and pieces of piano music. Real values of tones are mapped to positions within a one-dimensional walk. The structure of music, such as beat, measure and stanza, are reflected in the change of scaling exponents of the mean square fluctuation. Usually the pitches within one beat are nearly random, while nontrivial correlations are found within duration around a measure; for longer duration the mean square fluctuation is nearly flat, indicating exact 1/f power spectrum. Some interesting features are observed. Correlations are also studied by treating different tones as different symbols. This kind of correlation cannot reflect the structure of music, though long-range power-law is also discovered. Our results support the viewpoint that the fundamental principle of music is the balance between repetition and contrast.
THE FRACTAL DIMENSION OF A UNION OF TRINOMIAL ARCS
Authors: DUBUC S. , ZAOUI M.
Published: May 2003

We consider a specific subset Γ of the unit disk that is a countable union of arcs, these arcs being solutions of the equations zn=αzk+1 -α, α∈(0, 1). We will show that the Minkowski dimension of Γ is 3/2. Two intermediate results concern bounds, one for the length of a curve p=f(θ) when f is monotonic and another for the area of the Minkowski sausage of a curve of finite length.
LAYER GROWTH AND ALLOY FORMATION OF Ir ON Fe(100)
Authors: PFANDZELTER R. , WINTER H.
Published: May 2003

The growth mode and chemical structure of Ir deposited on Fe(100) are studied by specular reflection of fast ions and ion-induced Auger-electron spectroscopy. Temperatures below 500 K lead to a rough growth front, which is in agreement with a statistical growth of Ir atoms. For higher temperatures, we observe a layer-by-layer growth mode, where the Ir film is completely terminated by Fe atoms.
MERGING DATABASES UNDER CONSTRAINTS
Authors: LIN JINXIN , MENDELZON ALBERTO O.
Published: May 2003

The problem of integrating information from conflicting sources comes up in many current applications, such as cooperative information systems, heterogeneous databases, and multiagent systems. We model this by the operation of merging first-order theories. We propose a formal semantics for this operation and show that it has desirable properties, including abiding by majority rule in case of conflict and syntax independence. We apply our semantics to the special case when the theories to be merged represent relational databases under integrity constraints. We then present a way of merging databases that have different or conflicting schemas caused by problems such as synonyms, homonyms or type conflicts mentioned in the schema integration literature.
DISTRIBUTED QUERY SCHEDULING SERVICE: AN ARCHITECTURE AND ITS IMPLEMENTATION
Authors: LIU LING , PU CALTON , RICHINE KIRILL
Published: May 2003

We present the systematic design and development of a distributed query scheduling service (DQS) in the context of DIOM, a distributed and interoperable query mediation system.26 DQS consists of an extensible architecture for distributed query processing, a three-phase optimization algorithm for generating efficient query execution schedules, and a prototype implementation. Functionally, two important execution models of distributed queries, namely moving query to data or moving data to query, are supported and combined into a unified framework, allowing the data sources with limited search and filtering capabilities to be incorporated through wrappers into the distributed query scheduling process. Algorithmically, conventional optimization factors (such as join order) are considered separately from and refined by distributed system factors (such as data distribution, execution location, heterogeneous host capabilities), allowing for stepwise refinement through three optimization phases: Compilation, parallelization, site selection and execution. A subset of DQS algorithms has been implemented in Java to demonstrate the practicality of the architecture and the usefulness of the distributed query scheduling algorithm in optimizing execution schedules for inter-site queries.
ANGIONEOGENESIS AROUND INDUCED BONE WITH RECOMBINANT HUMAN BMP-2 IN A LATISSIMUS DORSI MUSCLE FLAP
Authors: Akioka Jiro , Kusumoto Kenji , Bessho Kazuhisa , Sonobe Junya , Kaihara Shinji , Wang Yibiao , Iizuka Tadahiko , Ogawa Yutaka
Published: May 2003

Bony tissue induced with recombinant human bone morphogenetic protein-2 (rhBMP-2) in the latissimus dorsi muscle flap (LDMF) of rats was investigated in angiography and histological examination. In five rats, rhBMP-2 with atelopeptide type I collagen (CL) as a carrier was implanted in the muscle pocket of LDMF. In five controls, only CL was implanted in the same manner. Three weeks after the implant, contrast medium was injected into the assending aorta. The LDMF was cut off at the base and exposed in soft X-ray. The implant and the surrounding tissue were then histologically examined.

In the rhBMP-2-implant group, the vascularity was richer, especially around the implant, and radiated to the induced bony tissue. Contrast medium was observed in the vascular cavities of the marrow inside the trabeculae. In the controls, the vascularity was relatively poor and the remnant CL occupied the whole implant space.

This study indicated that rhBMP-2 does not only induce trabeculae in muscle tissue, but also in the marrow, including vessels in the implant and the vascular system around the implant. Then, the induced bony tissue is supported in the circulation by the circulation by the vascular system, as a functional osseous tissue. This phenomenon may be highly beneficial in endogenous tissue engineering and regenerative medicene for skeletal reconstruction using BMP in the future.
BONE INDUCTION BY BMP-2 EXPRESSING ADENOVIRAL VECTOR IN RATS UNDER TREATMENT WITH FK506
Authors: Sonobe Junya , Bessho Kazuhisa , Kaihara Shinji , Okubo Yasunori , Iizuka Tadahiko
Published: May 2003

The purpose of this study was to investigate the effectiveness of human bone morphogenetic protein-2 (BMP-2) expressing adenoviral vector in vivo. The day before vector injection, immunosuppressant FK506 was given subcutaneously to each rat at doses of 12 mg/kg (Group I), 6 mg/kg (Group II) and 3 mg/kg (Group III). FK506 was not administered to the six rats of the control group. Twenty-five liters of AXCAOBMP-2 (3.93 × 109pfu/ml) were injected into the right calf muscle of all rats. On day 21 after vector injection, all groups were investigated radiologically, histologically, and biochemically. Osteoinduction was seen in the AxCAOBMP-2-injected groups with immunosuppression. However, no bone formation was observed in the control group. These findings suggest that AxCAOBMP-2 has the potential of osteoinduction under transient immunosuppression. AxCAOBMP-2 may be useful for future clinical application in bone reconstruction, if host immunity response can be regulated.
PRE-CLINICAL AND CLINICAL EXPERIENCES WITH BMP-2 AND BMP-7 IN SINUS FLOOR ELEVATION SURGERY: A COMPARISON
Authors: Zijderveld S. A. , Giltaij L. R. , van den Bergh J. P. A. , ten Bruggenkate C. M. , Tuinzing D. B.
Published: May 2003

The autogenous bone graft, still the golden standard in oral and maxillofacial surgery, needs a second side surgery. As an alternative, bone morphogenetic proteins (BMP-2 and BMP-7) have been searched in pre-clinical and clinical studies, specifically in sinus augmentation. A comparison of the aforementioned studies revealed very different results, also due to variations in study model. The available data on use of rhBMP-2 and 7 are promising in showing an osteoinductive potential in sinus augmentation, but not conclusive in the predictability and consistency results to allow clinical use in this stage, other than in well designed clinical trials.
BMP AS AN ALTERNATIVE TO AUTOGRAFT FOR SPINAL ARTHRODESIS
Authors: Magin Michael N. , Giltaij Lex R.
Published: May 2003

The gold standard in spinal arthrodesis is still given by the use of autograft. Additional operations to obtain bone grafts increase morbidity and strain for the patient, but do not always provide bone with sufficient primary stability and high osteogenic potential. Despite the use of large-scale conventional techniques, applying posterior and anterior access, failures still occur and lead to loss of correction or, even worse, to persistent instability. Therefore, a study has been designed to determine whether spinal arthrodesis could improved by the use of BMP-7, a potent growth factor with osteogenic properties, in comparison with autograft. Following disc removal and monosegmental instrumentation of the sheep lumbar spine, we compared interbody fusion at six months after administration of autogenous iliac crest bone graft, and BMP-7 (rhOP-1). Spinal arthrodesis quality was examined by plain X-ray, computed tomography (CT scan), biomechanical testing and histological evaluation. All examination methods demonstrated superior fusion after administration of BMP. Autograft eventually produced bony healing in most cases, however of a lower quality than with BMP. The results indicate that the use of BMP is enhancing vertebral arthrodesis in sheep. As well as offering the potential for improved bone healing, the use of BMP may permit less invasive surgery, such as vertebroplasty, kyphoplasty or application of cages, and help to avoid donor site morbidity.
BMP-7 IN ORTHOPEDIC APPLICATIONS: A REVIEW
Authors: Giltaij Lex R.
Published: May 2003

In recent years, significant progress has been made on the research of Bone Morphogenetic Protein-7, BMP-7 (OP-1). BMP-7 is a growth- and differentiating-factor and a member of the TGF-β or Transforming Growth Factor-beta Superfamily. Ever since recombinantly produced human BMP-7 (rhBMP-7) became available in the early 1990s research in this area intensified. Many publications and presentations were issued detailing the ability of rhBMP-7 to induce new bone formation and to investigate this as an option to solve a wide variety of orthopedic problems.

BMP-7's activity in bone regeneration has been established through numerous animal trials. Work has been presented on the potency of rhBMP-7 in joint revision arthroplasty, fracture healing and spinal fusion. rhBMP-7 has been investigated in a prospective controled human trial as an alternative for autograft in the treatment of tibial non-unions. In the not too distant future surgeons may have a new tool available in their daily practice for stimulating regeneration of bone and other skeletal tissue, though still many question on issues like dosing, predictability of outcomes, suitable indications and surgical techniques remain yet unanswered.
PROKARYOTIC EXPRESSION OF RECOMBINANT MOUSE OP-1 AND ITS OSTEOGENESISIN VITRO
Authors: Lu Zhenhua , Lindholm T. Sam
Published: May 2003

OP-1 is a main member of the BMP family. It plays diverse and significant roles in growth and differentiation. RT-PCR amplified the open reading frame of mouse OP-1 from cDNAs synthesis from CD-1 mouse embryo. By coding the gene of mOP-1 was inserted into pTrcHis 2B, the prokaryotic expression vector through IPTG induction, and the recombinant protein was isolated and purified with Ni-NTA resin. In an ALP activity assay, rmOP-1 has shown osteogenesis activity in vitro. It would offer a fast and inexpensive means of the productions of recombinant protein and an easy tool for growth and development research on rmOP-1.
IN VIVO SERIAL CHANGES IN BONE INDUCTION BY E. COLI-DERIVED RECOMBINANT HUMAN BMP-2
Authors: Bessho Kazuhisa , Sinobe Junya , Kaihara Shinji , Kawai Mariko , Okubo Yasunori , Maeda Jun-Ichiro , Akagi Homare , Iizuka Tadahiko
Published: May 2003

At present, several recombinant human bone morphogenetic proteins (rhBMPs) can be produced in mammalian cells. If rhBMPs with a high activity could be produced in bacteria, the bacterial expression system is very useful in clinic. We examined in vivo serial changes in the bone inducing ability of an Escherichia coli-derived rhBMP-2 (ErhBMP-2) variant with N-terminal sequence. Five μg of ErhBMP-2 was mixed with 3 mg of atelopeptide type I collagen (CL) as the carrier, and specimens were implanted into calf muscle pouches of Wistar rats (n = 20). After 3, 7, 14 and 21 days, 5 specimens each were examined. New cartilage was observed 7 days after implantation of ErhBMP-2 with CL. Induced bone was found on the outermost edge of the implant after 14 days. After 21 days, bone formation was associated with much fatty marrow. ALP activity and calcium content gradually increased with time. These changes were similar to those in a study using Chinese hamster ovary cell-derived rhBMP-2. However, these increases were slightly higher than those in the rhBMP-2 study. From these findings, ErhBMP-2 appears to be completely renatured while maintaining its biological activity. ErhBMP-2 with CL may expand by absorbing body fluid in vivo to greater extent than rhBMP-2 with CL, because it lacks heparin-binding sites. A variant ErhBMP-2 showing high activity in vivo, obtained by the bacterial expression system is an important finding, as it should be possible to produce large quantities of ErhBMP-2 at a low-cost for clinical use, in the near future.
Unilateral boundary value problems with jump discontinuities
Authors: Halidias Nikolaos
Published: May 2003

Using the critical point theory of Szulkin (1986), we study elliptic problems with unilateral boundary conditions and discontinuous nonlinearities. We do not use the method of upper and lower solutions. We prove two existence theorems: one when the right‐hand side is nondecreasing and the other when it is nonincreasing.
On Sakaguchi functions
Authors: Yang Ding-Gong , Liu Jin-Lin
Published: May 2003

Let Ss(α)(0 ≤ α < 1/2) be the class of functions
f(z) = z + ⋯ which are analytic in the unit disk and satisfy
there Re{zf′(z)/(f(z) − f(−z))} > α. In the present paper, we find the sharp lower bound on Re{(f(z) − f(−z))/z} and investigate two subclasses S0(α) and T0(α) of Ss(α). We derive sharp distortion inequalities and some
properties of the partial sums for functions in the classes
S0(α) and T0(α).
On the weak uniform rotundity of Banach spaces
Authors: Chang Wen D. , Chang Ping
Published: May 2003

We prove that if Xi, i = 1, 2, …, are Banach spaces that are weak* uniformly rotund, then their lp product space (p > 1) is weak* uniformly rotund, and for any weak or weak* uniformly rotund Banach space, its quotient space is also weak or weak* uniformly rotund, respectively.
First hitting times of simple random walks on graphs with congestion points
Authors: Kang Mihyun
Published: May 2003

We derive the explicit formulas of the probability generating
functions of the first hitting times of simple random walks on
graphs with congestion points using group representations.
On the largest analytic set for cyclic operators
Authors: Bourhim A.
Published: May 2003

We describe the set of analytic bounded point evaluations for an
arbitrary cyclic bounded linear operator T on a Hilbert space
ℋ; some related consequences are discussed. Furthermore, we
show that two densely similar cyclic Banach‐space operators
possessing Bishop′s property (β) have equal approximate point spectra.
Topological duals of some paranormed sequence spaces
Authors: Rath Nandita
Published: May 2003

Let P = (pk) be a bounded positive sequence and let
A = (ank) be an infinite matrix with all ank ≥ 0. For normed spaces E and Ek, the matrix A generates the
paranormed sequence spaces [A, P] ∞((Ek)), [A, P] 0((Ek)), and [A, P]((E)), which generalise almost
all the well‐known sequence spaces such as c0, c, lp, l∞, and wp. In this paper, topological duals of
these paranormed sequence spaces are constructed and general
representation formulae for their bounded linear functionals are
obtained in some special cases of matrix A.
Convergence theorems for generalized projections and maximal monotone operators in Banach spaces
Authors: Ibaraki Takanori , Kimura Yasunori , Takahashi Wataru
Published: May 2003

We study a sequence of generalized projections in a reflexive, smooth, and strictly convex Banach space. Our result shows that Mosco convergence of their ranges implies their pointwise convergence to the generalized projection onto the limit set. Moreover, using this result, we obtain strong and weak convergence of resolvents for a sequence of maximal monotone operators.
On a two‐point boundary value problem for second‐order differential inclusions on Riemannian manifolds
Authors: Gliklikh Yuri E. , Obukhovskiĭ Andrei V.
Published: May 2003

We consider second‐order differential inclusions on a Riemannian manifold with lower semicontinuous right‐hand sides. Several existence theorems for solutions of two‐point boundary value problem are proved to be interpreted as controllability of special mechanical systems with control on nonlinear configuration spaces. As an application, a statement of controllability under extreme values of controlling force is obtained.
On the weak solution of a three‐point boundary value problem for a class of parabolic equations with energy specification
Authors: Bouziani Abdelfatah
Published: May 2003

This paper deals with weak solution in weighted Sobolev spaces, of three‐point boundary value problems which combine Dirichlet and integral conditions, for linear and quasilinear parabolic equations in a domain with curved lateral boundaries. We, firstly, prove the existence, uniqueness, and continuous dependence of the solution for the linear equation. Next, analogous results are established for the quasilinear problem, using an iterative process based on results obtained for the linear problem.
Existence results for general inequality problems with constraints
Authors: Dincă George , Jebelean Petru , Motreanu Dumitru
Published: May 2003

This paper is concerned with existence results for inequality problems of type F0(u; v) + Ψ′(u; v) ≥ 0, for all v ∈ X, where X is a Banach space, F : X → ℝ is locally Lipschitz, and Ψ : X → (−∞ + ∞] is proper, convex, and lower semicontinuous. Here F0 stands for the generalized directional derivative of F and Ψ′ denotes the directional derivative of Ψ. The applications we consider focus on the variational‐hemivariational inequalities involving the p‐Laplacian operator.
Analysis of a multiple‐porosity model for single‐phase flowthrough naturally fractured porous media
Authors: Spagnuolo Anna Maria , Wright Steve
Published: May 2003

A derivation of a multiple‐porosity model for the flow of a single phase, slightly compressible fluid in a multiscale, naturally fractured reservoir is presented by means of recursive use of homagnetization theory. We obtain a model which generalizes the double‐porosity model of Arbogast et al. (1990) to a flow system with an arbitrary finite number of scales.
On generalized derivatives for C1,1 vector optimization problems
Authors: La Torre Davide
Published: May 2003

We introduce generalized definitions of Peano and Riemann directional derivatives in order to obtain second‐order optimality conditions for vector optimization problems involving
C1,1 data. We show that these conditions are stronger than those in literature obtained by means of second‐order Clarke subdifferential.
Roles of Cardiac Transcription Factors in Cardiac Hypertrophy
Authors: Akazawa Hiroshi , Komuro Issei
Published: May 2003

Different cell types, equipped with unique structure and function, synthesize different sets of proteins on the basis of different patterns of gene expression, even though their genomes are identical. Cardiac transcription factors have been reported to control a cardiac gene program and thus to play a crucial role in transcriptional regulation during embryogenesis. Recently, postnatal roles of cardiac transcription factors have been extensively investigated. Consistent with the direct transactivation of numerous cardiac genes reactivated in response to hypertrophic stimulation, cardiac transcription factors are profoundly involved in the generation of cardiac hypertrophy or in cardioprotection from cytotoxic stress in the adult heart. In this review, the regulation of a cardiac gene program by cardiac transcription factors is summarized, with an emphasis on their potential role in the generation of cardiac hypertrophy.
Tissue Engineering Therapy for Cardiovascular Disease
Authors: Nugent Helen M. , Edelman Elazer R.
Published: May 2003

The present treatments for the loss or failure of cardiovascular function include organ transplantation, surgical reconstruction, mechanical or synthetic devices, or the administration of metabolic products. Although routinely used, these treatments are not without constraints and complications. The emerging and interdisciplinary field of tissue engineering has evolved to provide solutions to tissue creation and repair. Tissue engineering applies the principles of engineering, material science, and biology toward the development of biological substitutes that restore, maintain, or improve tissue function. Progress has been made in engineering the various components of the cardiovascular system, including blood vessels, heart valves, and cardiac muscle. Many pivotal studies have been performed in recent years that may support the move toward the widespread application of tissue-engineered therapy for cardiovascular diseases. The studies discussed include endothelial cell seeding of vascular grafts, tissue-engineered vascular conduits, generation of heart valve leaflets, cardiomyoplasty, genetic manipulation, and in vitro conditions for optimizing tissue-engineered cardiovascular constructs.
REVIEWS
Authors: Levitt James N.
Published: May 2003

Book reviewed in this article:

Digital Places: Building Our City of Bits, by Thomas A. Horan.
REVIEWS
Authors: Allenby Braden R.
Published: May 2003

Book reviewed in this article:

The Rise of the Network Society, by Manuel Castells.
REVIEWS
Authors: Cohen Nevin
Published: May 2003

Book reviewed in this article:

Information Systems and the Environment, edited by Deanna J. Richards, Braden R. Allenby, and W. Dale Compton.
Thermodynamics from first principles: temperature and composition of the Earth’s core
Authors: Alfé D. , Gillan M. J. , Price G. D.
Published: May 2003

We summarize the main ideas used to determine the thermodynamic properties of pure systems and binary alloys from first principles calculations. These are based on the ab initio calculations of free energies. As an application we present the study of iron and iron alloys under Earth,s core conditions. In particular, we report the whole melting curve of iron under these conditions, and we put constraints on the composition of the core. We found that iron melts at 6350士600 K at the pressure corresponding to the boundary between the solid inner core and the liquid outer core (ICB). We show that the core could not have been formed from a binary mixture of Fe with S, Si or O and we propose a ternary or quaternary mixture with 8—10% of S/Si in both liquid and solid and an additional ~8% of oxygen in the liquid. Based on this proposed composition we calculate the shift of melting temperature with respect to the melting temperature of pure Fe of ~—700 K, so that our best estimate for the temperature of the Earth's core at ICB is 5650±600 K.
Laser Raman identification of silica phases comprising microtextural components of sinters
Authors: Rodgers K. A. , Hampton W. A.
Published: May 2003

Laser Raman spectroscopy is particularly well suited for routine characterization of the crystalline and the better ordered paracrystalline silica phases occurring in silica sinters: opal-C, quartz and moganite. The non-crystalline and poorly ordered paracrystalline silica phases (opal-CT and opal-A) are identified with difficulty, partly as a result of the high level of fluorescence exhibited by the younger sinters that are dominated by these phases, and partly as a result of the ill-defined nature of the broad phonon scattering bands produced by them. Nonetheless, given the limited number of phases present and the high level of phonon scattering from the better ordered phases, judicious use of a Raman microprobe enables the character of most siliceous microtextural sinter components to be determined readily. Microprobe examination of a series of New Zealand sinters, ranging from Late Quaternary to Pliocene in age shows that a silica phase inhomogeneity that exists in some outcrops reflects an underlying phase heterogeneity obtaining in the microstructure of the sinter; it is a consequence of the phase transformation process. In the older sinters, quartz, moganite and opaline cristobalite may be present in a single fabric element but in quite different proportions to their abundance in adjacent elements. Identification of opaline lepispheres partially pseudomorphed by quartz+moganite and the association of quartz+moganite in microcrystals exhibiting common quartz forms, cautions against the use of morphology as a means of identifying silica phases at the microstructural level.
Crystal structure refinement of sahlinite Pb14(AsO4)2O9Cl4
Authors: Bonaccorsi E. , Pasero M.
Published: May 2003

The crystal structure of sahlinite [Pb14(AsO4)2O9Cl4] from Lågban (Sweden) has been refined up toR= 0.071 using single-crystal diffraction data collected at the Elettra synchrotron facility. Sahlinite is monoclinic, space group C2/c, witha= 12.704(4),b= 22.576(5),c= 11.287(4) Å, β = 118.37(3)°. Sahlinite is isostructural with kombatite, its vanadium counterpart. Both are derivatives of the litharge form of PbO. In the structure of sahlinite there are seven independent Pb atoms, which are linked to Cl and/or O atoms, with coordination number ranging from V to VIII. The coordination polyhedra are irregularly shaped, due to the 6s2lone-pair effect displayed by Pb2+.
Modes and textures of secondary minerals on Chinese coins of different ages
Authors: Fang J. N. , Tan L. P. , Huang E.
Published: May 2003

A thorough assessment of the secondary minerals on 796 Chinese Pb-Cu-Sn-Zn bronze coins from ∼1100 BC to AD 1911 has been made. Malachite is found on more than 80% of the coins irrespective of their dynasties, but a botryoidal texture is only observed on the coins of the Song dynasty or older. Azurite, however, is seen in microscopic quantities on a single coin of ∼AD 1800, but is clearly visible on the Ming dynasty or older coins. Cerussite is a common secondary mineral of the Qin dynasty and older coins, though it has not been found on the Qing dynasty or younger coins. Cuprite is observed on the Song dynasty and older coins.
Tripuhyite, FeSbO4, revisited
Authors: Berlepsch P. , Armbruster T. , Brugger J. , Criddle A. J. , Graeser S.
Published: May 2003

The exact nature of tripuhyite remains controversial more than 100 years after the first description of the mineral. Different stoichiometries and crystal structures (rutile or tri-rutile types) have been suggested for this Fe-Sb-oxide. To address these uncertainties, we studied tripuhyite from Tripuhy, Minas Gerais, Brazil (type material) and Falotta, Grisons, Switzerland using single-crystal and powder X-ray diffraction (XRD), optical microscopy and electron microprobe analysis.

Electron microprobe analyses showed the Fe/Sb ratios to be close to one in tripuhyite from both localities. Single crystal XRD studies revealed that tripuhyite from the type locality and from Falotta have the rutile structure (P42mnm, a = 4.625(4) c = 3.059(5) and a = 4.6433(10) c= 3.0815(9) Å, respectively). Despite careful examination, no evidence for a tripled c parameter, characteristic of the tri-rutile structure, was found and hence the structure was refined with the rutile model and complete Fe-Sb disorder over the cationic sites in both cases (type material: R1 = 3.61%; Falotta material: R1 = 3.96%). The specular reflectance values of type material tripuhyite and lewisite were measured and the following refractive indices calculated (after Koenigsberger): tripuhyite nmin = 2.14, nmax = 2.27; lewisite (cubic) n = 2.04.

These results, together with those of 57Fe and 121Sb Mössbauer spectroscopy on natural and synthetic tripuhyites reported in the literature, indicate that the chemical formula of tripuhyite is Fe3+Sb5+O4 (FeSbO4). Thus, tripuhyite can no longer be attributed to the tapiolite group of minerals of general type AB2O6. A comparison of the results presented with the mineralogical data of squawcreekite suggests that tripuhyite and squawcreekite are identical. In consequence, tripuhyite was redefined as Fe3+Sb5+O4 with a rutile-type structure. Both the proposed new formula and unit cell (rutile-type) of tripuhyite as well as the discreditation of squawcreekite have been approved by the Commission on New Mineral and Mineral Names (CNMMN) of the International Mineralogical Association (IMA).
A single crystal X-ray study of a sulphate-bearing buttgenbachite, Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O, and a re-examination of the crystal chemistry of the buttgenbachite-connellite series
Authors: Hibbs D. E. , Leverett P. , Williams P. A.
Published: May 2003

The single-crystal X-ray structure of a sulphate-bearing buttgenbachite, Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O, from Likasi, Democratic Republic of Congo, has been determined at 100 and 288 K. The basic framework of the structure is the same as has been previously reported for buttgenbachite, except for the identification of a hydrogen-bonded chloride ion (occupancy 0.6) at the origin instead of a Cu ion with partial occupancy. The nature of nitrate positional disorder along channels in the c direction and how this relates to the presence of other species such as chloride ions and water molecules and, most importantly, sulphate ions has been elucidated. One nitrate ion, with an occupancy of 0.18, lies at 2/3,l/3,l/4 and shares the site with a chloride ion (occupancy 0.30) and also a sulphate ion (occupancy 0.09); a second nitrate, with an occupancy of 0.24, lies at 2/3,1/3,0.084 and shares the site with a water molecule (occupancy 0.06). As a result, a formula of Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O is obtained. Re-refinement of deposited data for a supposed connellite crystal from the Toughnut mine,Tombstone, Arizona gives a related, but different, pattern of anion substitution. No sulphate could be detected in the structure and it is evident that this structure refers to buttgenbachite. A nitrate nitrogen atom and a chloride ion are disordered at 2/3,l/3,l/4, the overall site being fully occupied. A chloride ion with ∼0.5 occupancy is sited at the origin and the formula Cu36Cl7.9(NO3)1.1(OH)63.4H2O is indicated. Re-refinement of a deposited data set for another buttgenbachite crystal from the Likasi mine reveals a partially occupied nitrate centred at 2/3,l/3, z and a partially occupied chloride at 2/3,l/3,l/4. Either 0.5Cl–, OH–, H2O or H3O+ is located at the origin. If the latter is the case, the stoichiometry for this buttgenbachite is Cu36Cl6.5(NO3)1.5(OH)64.5.5H2O. The present study has highlighted the fact that a range of compositions for buttgenbachite exists, depending on the pH and relative activities of chloride, nitrate and sulphate ions in solutions from which the mineral crystallizes.
HighP-Texperimental metasomatism of a fluorapatite with significant britholite and fluorellestadite components: implications forLREEmobility during granulite-facies metamorphism
Authors: Harlov D. E. , Förster H.-J. , Schmidt C.
Published: May 2003

ALREE-, Si-, S-enriched fluorapatite with ∼7.7 wt.%LREE2O3, 5.3 wt.% SiO2and 3.5 wt.% SO3from the Mushugai-KhudukREEdeposit, southern Mongolia, has been experimentally metasomatized in pure H2O at 900°C and 1000 MPa. Despite the highLREEcontent, inclusions or rim grains of monazite did not form during fluid-induced metasomatism. Under high-contrast BSE imaging, the reacted fluorapatite presents a mottled appearance with light, moderate and dark areas and hosts large fluid inclusions containing anhydrite as the solid phase. Dark areas show moderate depletion in all theLREE.MeasurableHREEsuch as Gd and Y remain unchanged. In the areas of intermediate brightness, Ce and, to a lesser extent, La are moderately enriched relative to the original fluorapatite. In the light areas, Ce and La display strong enrichment, whereas the otherLREE,Gd and Y remain little changed. In the dark areas, depletion inLREEis matched by depletion in Si and Na, satisfying the coupled substitution reactions Si4+; + (LREE)3+= P5++ Ca2+and Na++ (LREE)3+= 2Ca2+. In the light areas, enrichment inLREEand P is accompanied by depletion in Si, Na and S, implying operation of two different coupled substitution reactions, namely: 2P5+= Si4++ S6+and 2P5++ LREE3+= 2S6++ Na+. In all areas, strong enrichment in F is accompanied by strong depletion in Cl and OH. The formation of large, fluid and anhydrite-filled inclusions associated with theLREE-enriched light areas is evidence of a negative volume change, combined with additional local dissolution of the fluorapatite. This occurred during the metasomatism of the original Cl- and OH-bearing fluorapatite to a nearly pure end-member fluorapatite. Local dissolution of fluorapatite in the space now occupied by the voids, combined with element remobilization from the body of the fluorapatite as a whole, provided the Ca and S needed for the formation of anhydrite as well as the P andLREErequired for the enrichment of the bright areas.
Space symmetry of prehnite，Ca2AI[6](Si3AIO10)(OH)2, from the Tieshan iron mineral deposit, Central China
Authors: Zhao W.-y. , Liu X.-w. , Wang Q.-y. , Zhang Q.-j.
Published: May 2003

The space symmetry of prehnite, a mineral which occurs in cavities and veins within skarn from the Tieshan iron mineral deposit, Daye, Hubei province, central China, has been determined using selected area electron diffraction (SAED) and convergent-beam electron diffraction (CBED) on the submicrometer scale. Our results confirm that natural prehnite may belong to space group Pncm. The unit-cell parameters of the prehnite investigated ( a = 0.458 nm, b = 0.555 nm and c = 1.853 nm) have been calculated using the multicrystal diffraction rings of gold, the internal standard.
Paragenesis and mineral chemistry of alabandite (MnS) from the Ag-rich Santo Toribio epithermal deposit, Northern Peru
Authors: Olivo G. R. , Gibbs K.
Published: May 2003

The Miocene, epithermal, Ag-rich polymetallic Santo Toribio deposit is hosted by the volcanics of the Quiruvilva-Pierina subbelt, Northern Peru, which also comprises the world-class, high sulphidation Pierina deposit. The Ag-rich, alabandite-bearing veins of the Santo Toribio deposit formed during two major stages. The early stage is characterized by deposition of arsenopyrite, pyrite, quartz, Mn- sphalerite, stannite, alabandite and minor miargyrite. Sphalerite associated with this stage is exceptionally enriched in Mn (up to 14.5 wt.%) and alabandite is optically and mineralogically zoned. Its brown zones have greater Fe+Sb and smaller Mn contents than the green zones and Fe+Sb replaces Mn in its structure. During this early stage, fs2 must have been high to allow the stabilization of alabandite relative to rhodochrosite. In the second stage, the physicochemical conditions changed and the CO2/S ratio increased, causing dissolution of alabandite and the deposition of abundant rhodochrosite and a second generation of arsenopyrite, pyrite and quartz, sphalerite with chalcopyrite inclusions, mirargyrite, ramdohrite, and finally stibnite. This polymetallic ore probably formed due to an abrupt decrease in H+ and/or Cl- concentration caused by boiling or dilution of the high-salinity hydrothermal fluids and constitutes an example of “intermediate sulfidation-state” epithermal deposits.
Raman spectroscopy of the minerals boléite，cumengéite， diaboléte and phosgenite — implications for the analysis of cosmetics of antiquity
Authors: Frost R. L. , Williams P. A. , Martens W.
Published: May 2003

The application of Raman spectroscopy to the study of the mixed cationic Pb-Cu and Pb-Cu-Ag minerals: boleite, cumengeite and diaboleite has enabled their molecular structures to be compared. Each of these three minerals shows different hydroxyl-stretching vibrational patterns, but some similarity exists in the Raman spectra of the hydroxyl-deformation modes. The low-wavenumber region is characterized by the bands assigned to the cation-chloride stretching and bending modes. Phosgenite is also a mixed chloride-carbonate mineral and a comparison is made with the molecular structure of the aforementioned minerals. Raman spectroscopy lends itself to the study of these types of minerals in complex mineral systems of secondary mineral formation.
The crystal structure of anthropogenic Pb2(OH)3(NO3), and a review of Pb-(O,OH) clusters and lead nitrates
Authors: Kolitsch U. , Tillmanns E.
Published: May 2003

The previously unknown crystal structure of the basic lead nitrate Pb2(OH)3(NO3) has been determined using single-crystal X-ray diffraction data (Mo-Kα radiation, CCD area detector). The compound is orthorhombic, space groupImmm,witha= 8.314(2),b= 8.545(2),c= 17.210(3)Å(R1 = 2.78% for 940 ‘observed’ reflections with Fo > 4σ(Fo)). The layered structure contains a previously unknown cuboid [Pb8(OH)12]4+cluster and NO3groups. The study used crystals formed by anthropogenic processes on a medieval mine dump, probably involving black gunpowder used in the blasting of ore. Pb2(OH)3(NO3) is associated with a second nitrate, Pb13O8(OH)6(NO3)4, which was previously designated as “Pb3O3(OH)4(NO3)2” or “Pb3(OH)5(NO3)”. It is rhombohedral, space group, witha= 10.263(1),c= 25.454(5) Å, and a structure solution is in complete agreement with an independent single-crystal study by Liet al.(2001). Probable hydrogen bonds in Pb2(OH)3(NO3) are indicated. Reported data onclusters and lead hydroxide and oxide nitrates are summarized and discussed critically. The probable conditions of formation of the studied samples are evaluated.
Advanced High School Biology in an Era of Rapid Change: A Summary of the Biology Panel Report from the NRC Committee on Programs for Advanced Study of Mathematics and Science in American High Schools
Authors: Wood William B.
Published: May 2003

A recently released National Research Council (NRC) report, Learning and Understanding: Improving Advanced Study of Mathematics and Science in U.S. High Schools, evaluated and recommended changes in the Advanced Placement (AP), International Baccalaureate (IB), and other advanced secondary school science programs. As part of this study, discipline-specific panels were formed to evaluate advanced programs in biology, chemistry, physics, and mathematics. Among the conclusions of the Content Panel for Biology were that AP courses in particular suffer from inadequate quality control as well as excessive pressure to fulfill their advanced placement function, which encourages teachers to attempt coverage of all areas of biology and emphasize memorization of facts rather than in-depth understanding. In this essay, the Panel's principal findings are discussed, with an emphasis on its recommendation that colleges and universities should be strongly discouraged from using performance on either the AP examination or the IB examination as the sole basis for automatic placement out of required introductory courses for biology majors and distribution requirements for nonmajors.
Processing, inversion, and interpretation of a 2D seismic data set from the North Viking Graben, North Sea
Authors: Madiba Gislain B. , McMechan George A.
Published: May 2003

Simultaneous elastic impedance inversion is performed on the 2D North Viking Graben seismic data set used at the 1994 SEG workshop on amplitude variation with offset and inversion. P‐velocity (Vp), S‐velocity (Vs), density logs, and seismic data are input to the inversion. The inverted P‐impedance and S‐impedance sections are used to generate an approximate compressional‐to‐shear velocity ratio (Vp/Vs) section which, in turn, is used along with water‐filled porosity (Swv) derived from the logs from two wells, to generate fluid estimate sections. This is possible as the reservoir sands have fairly constant total porosity of approximately 28 ± 4%, so the hydrocarbon filled porosity is the total porosity minus the water‐filled porosity.

To enhance the separation of lithologies and of fluid content, we map Vp/Vsinto Swvusing an empirical crossplot‐derived relation. This mapping expands the dynamic range of the low end of the Vp/Vsvalues. The different lithologies and fluids are generally well separated in the Vp/Vs–Swvdomain.

Potential hydrocarbon reservoirs (as calibrated by the well data) are identified throughout the seismic section and are consistent with the fluid content estimations obtained from alternative computations.

The Vp/Vs–Swvplane still does not produce unique interpretation in many situations. However, the critical distinction, which is between hydrocarbon‐bearing sands and all other geologic/reservoir configurations, is defined. Swv≤ 0.17 and Vp/Vs≤ 1.8 are the criteria that delineate potential reservoirs in this area, with decreasing Swvindicating a higher gas/oil ratio, and decreasing Vp/Vsindicating a higher sand/shale ratio. As these criteria are locally calibrated, they appear to be valid locally; they should not be applied to other data sets, which may exhibit significantly different relationships. However, the overall procedure should be generally applicable.