bluuebunny/crossref_metadata_2025 huggingface dataset:
Method of endoscopy in the chimpanzee: Relations of ovarian anatomy, endometrial histology and sexual swelling
Authors: Graham C. E. , Keeling M. , Chapman C. , Cummins L. B. , Haynie J.
Published: August 2005

Endoscopy was performed on adult female chimpanzees at various intervals before and after detumescence of the sexual swelling. The method required inhalation anesthesia, Trendelenberg positioning, abdominal insufflation with CO2 and a 10 mm photo‐endoscope inserted infra‐umbilically. Accessory instruments were introduced into each of the lower quadrants. Mechanical ventilation and careful physiologic monitoring were necessary to control cardiac arrhythmias.

Before detumescence of the swelling, unovulated follicles were observed. Immediately after detumescence of the swelling began, ovulated follicles or early corpora lutea were present. Secretory endometria and plasma progesterone values in excess of 4.0 mg/ml did not occur until three days after detumescence of the sexual swelling commenced.

Endoscopic ovarian visualization offers a means of establishing accurate correlations between ovarian morphology and other parameter in chimpanzee menstrual cycles. The data presented support the interpretation that in this species, ovulation and sexual swelling detumescence are closely related in time.
Racial differences in anthropometric traits in school children of Bahia, Brazil
Authors: Oliveira Maria Piedade M. S. , Azevědo Eliane S.
Published: August 2005

Two thousand four hundred and forty‐four Brazilian school children were classified as Light, Medium and Dark according to a subjective judgment of the proportion of Negro admixture, and studied for weight, height, span and upper‐segment/lower‐segment (US/LS) ratio. The mean US/LS ratio decreases significantly as the proportion of Negro admixture increases giving an intermediate value for those children belonging to the Medium group for race.
Locomotor adaptations within the Cercopithecus genus: A multivariate approach
Authors: Manaster B. J.
Published: August 2005

Multivariate analysis as a technique for investigating locomotor differentiation among primates has proven its power and usefulness in many studies on various skeletal dimensions. In these analyses primate genera were distributed and sometimes clustered in a manner that was interpretable based on current knowledge of gross locomotor differences. In an effort to advance our understanding of arboreality and terrestriality in primates, the present research involves a careful look for the most subtle morphological differences in locomotor behavior. It is believed that by looking at such subtle shape differences an understanding of what it means morphologically for a primate to be either more or less arboreal may be achieved.

The species within the primate genus Cercopithecus were analyzed. This genus includes species which may be placed along a habitat (ground‐living to tree‐dwelling) or activity spectrum. The different habitats or activity patterns clearly require slight variations in patterns of movement, which in turn may require subtle structural adaptations.

Multivariate analyses of 67 postcranial variables on seven species within the genus allowed detection of slight degrees of morphological variation. However, when morphological differences are small, size variance among specimens may take on an inflated importance. A substantial amount of work was devoted to finding the least biased method of removing size variance from the variables while incorporating a discrete size variable into the study. Using these transformed skeletal variables, interspecific groupings were discovered. Much of this infrastructure is then related to differing locomotor behavior and provides an insight into the fine structure of primate locomotor adaptation in an arboreal habitat.
The physical growth of high altitude Bolivian Aymara children
Authors: Stinson Sara
Published: August 2005

This study describes the growth characteristics of Aymara children living in Ancoraimes, Bolivia at altitudes between 3800 and 4000 meters. Anthropometric measurements were made on 510 children between the ages of 6. 0 and 20. 9 years, 360 males and 150 females. The growth pattern of Ancoraimes Aymara children is very similar to that of other high altitude Andean populations. They are greatly delayed in height and weight, exhibit little sexual dimorphism in body size and relative to stature, have larger chest dimensions than U.S. children. Compared to Quechua children living at higher altitudes in Peru, Ancoraimes children tend to be taller and heavier but have significantly smaller chest dimensions. Although the causes of the size differences between these two groups are not entirely clear, they may be due to the different altitudes at which the groups reside.
Metrical analysis of the basicranium of extant hominoids and Australopithecus
Authors: Dean M. C. , Wood B. A.
Published: August 2005

The size and shape of the basicranium (seen in norma basilaris) in Homo, Gorilla, Pan, Pongo, and Australopithecus have been studied by recording the relative disposition of midline and bilateral bony landmarks. Fifteen linear measurements and two angles were used to relate the landmarks. The relatively longer and narrower cranial base of Gorilla, Pan, and Pongo is clearly contrasted with the wider, shorter cranial base in Homo sapiens. When the same observations were made on two “robust” and two “gracile” australopithecine crania, marked differences were found between the taxa. In the two “robust” specimens, the foramen magnum is located relatively further forward, and the axis of the petrous temporal bone is aligned more nearly with the coronal plane than in the two “gracile” crania.

The implications of this apparent parallelism in basicranial morphology between Homo sapiens and the “robust” australopithecines are discussed.
Structural strength of the macaque femur
Authors: Burr David B. , Piotrowski George , Miller Gary J.
Published: August 2005

New techniques in bone mechanics, and the demonstration that locomotor function can be interpreted based on patterns of structural strength delineated by these new techniques, lay the foundation for analyses of structural strength in nonhuman primate long bones. The present paper details topographic variability in structural strength of the femoral diaphysis of Macaca as a basis for further quantifying form‐function interactions in pronograde primates. The femoral diaphyses of 42 macaques were serially sectioned. These sections were digitized, and coordinate points were submitted to the SCADS computerized stress analysis program. This analysis indicated that the femoral diaphysis of Macaca is better adapted proximally than distally to resist axial loads. The proximal third of the femur is better able to resist bending loads in the posterolateral/anteromedial direction than in the standard planes. The distal femur is geometrically well suited to resist high bending loads, particularly in the mediolateral plane. The elliptical construction of the distal femur is designed to resist high torsional loads as well. When compared with density data on the macaque femoral diaphysis, these data indicate extremely high rigidity in the mediolateral plane. The inverse relationship between density and structural rigidity distally indicates the presence of compensatory mechanisms between structural strength, geometry, and density. Similarities in femoral mechanics in macaques and humans suggest uniformity of stress patterns of the lower extremity in terrestrial quadrupedal and bipedal locomotion.
Peopling of Andean South America
Authors: Rothhammer Francisco , Silva Claudio
Published: August 2005

Archeological, craniometrical, and genetic information is utilized to reconstruct possible migration routes used in the peopling of Andean South America. Special emphasis is given to the elaboration of craniometrical isoline maps and its application in testing models of population displacement based on archeological data. A genetic distance analysis among linguistic groupings complements the conclusions based on archeological and craniometrical information.
Corpus callosum in sexually dimorphic and nondimorphic primates
Authors: Holloway Ralph L. , Heilbroner Peter
Published: August 2005

The midsagittal area and other morphological measures were taken on the corpus callosum of four different species of primate: Macaca mulatta, M. fascicularis, Callithrix jacchus, and Saguinus oedipus. The first two species are strongly dimorphic, whereas the New World forms show little dimorphism with regard to overall body size, canines, and brain weight.

Neither total corpus callosal area (TOTALCC), or other parts of the corpus callosum (CC) showed any significant sexual dimorphism in any of the primate species sampled. Only in M. mulatta did a sexual dimorphism appear to be significant. In males of this species, the dorsoventral width of the splenium was larger than in females. In addition, the anterior commissure (ANTCOMM) evinced no sexual dimorphism in the different species.

Brain weight was significantly dimorphic in only M. mulatta, and when ratio data were used to correct for brain weight, no significant differences were found in the corpus callosum. This is in contrast to Homo sapiens, where the relative size of the CC has been reported to be larger in females, and particularly so in the posterior, or splenial portion of the CC. Correlation coefficients were calculated for the various variables within each species. In general, most of the callosal measures are significantly inter‐correlated, although the exact pattern varies for each species.

Thus, unlike Homo sapiens, or pongids such as Gorilla and Pan, neither New nor Old World monkeys show any striking evidence for sexual dimorphism in the corpus callosum.
Modelling of adsorption in cyclic operation of a PSA plant for H2 recovery
Authors: Brüggendick Hermann , Richter Ekkehard , Knoblauch Karl , Jüntgen Harald
Published: August 2005

A pressure swing adsorption process for hydrogen recovery from coke oven gases comprises the steps of adsorption at pressures above 6 bar, cocurrent and countercurrent depressurization, purging with hydrogen at ambient pressure and repressurization. The process was investigated in the cyclic mode, on a laboratory scale, using an adsorber filled with 1.3 litres of carbon molecular sieve. Based on the test results of concentrations and pressures within the adsorber during complete cycles, a pseudo‐homogeneous model was developed for the adsorption step. Adsorption equilibrium parameters were determined by separate measurements, while the transport parameters were evaluated by fitting the experiments of the fixed bed adsorber. It was possible to consider the residual load, resulting from an incomplete regeneration, by the assumption of a load distribution in the inlet region of the adsorber.
Dynamic behavior and operational aspects of heat‐integrated distillation processes
Authors: Lang Lothar
Published: August 2005

Complex configurations of distillation columns have been shown to consume less energy than simple configurations. These complex configurations mainly results from two considerations: either a feed split, where the condensing vapor from the top of the high pressure column is used to heat the reboiler of the low pressure column, or the overheads from a high pressure column in a distillation train used to reboil a column under lower pressure. Industrial experience shows that very often in these configurations there is still incentive for more energy reduction simply because of inefficient control. The energy integration increases the control loop coupling the system, so that the operating strategy for the columns is no longer apparent. Therefore, the dynamic behaviour and the operational constraints of such systems become very important. The use of rigorous dynamic model of the processes is an essential instruments to pursue the goal of good and reliable process control Such models allow the engineer to realistically simulate the process with the desired control system in place and to analyze the effects of equipment sizing, hest integration, and disturbances. Variable pairing proved is used to illustrate that effective control of energy‐integrated distillation columns can be achieved by proper selection of manipulated variables and pairing them correctly with control variables. Hints will also be given, when multivariable predictive control schemes should be used.
Boron as a Bridging Ligand
Authors: Braunschweig Holger , Whittell George R.
Published: August 2005

The Lewis acidity of [(η5‐C5R5)Fe(CO)2(BX2)] (1: R=H, X=Cl) and the robust nature of the constituent FeB bond have been demonstrated by reaction with 4‐methylpyridine to yield the corresponding Lewis acid–base adduct. These properties have subsequently been utilised in the construction of heterodinuclear bridging borylene, bridging boryl and μ2‐boride complexes from analogues 3 (R=Me, X=Br) and 5 (R=Me, X=Cl). All the bimetallic species so formed exhibited unprecedented coordination modes for boron.
The shifting gamma perception
Authors: Besuijen J.
Published: August 2005

True to life, color display and color management depend on a proper technical model of the display used. Current gamma models and fitting procedures are not accurate in modeling the lower part of the tone reproduction curve. The GOG‐ and GOGO‐model used in color management standards tend to clip the luminance to zero for digital values were luminance can be seen and measured. Two improvements to the models are suggested. First, the models should be fitted by optimizing the root mean square error (RMSE) of the CIE lightness instead of the luminance. Second, a shifting gamma model is adopted, with gamma increasing in value for lower voltages. Results show that the adapted models correspond better with the luminance measurements. The clipping values are nearer to the measured zero luminance threshold, and the average RMSE and ΔE over the whole scale are smaller. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 332–340, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.
Theoretical analysis of subtractive color mixture characteristics III—Realistic colorants and single tristimulus dimension
Authors: Matsushiro Nobuhito , Ohta Noboru
Published: August 2005

Continuing our work to further understand the characteristics of stimulus values of a single tristimulus dimension in colors obtained by subtractive color mixture, discussions proceed related to realistic colorants. New theorems are intended to provide for the establishment of bounds for realistic colorants in mixtures when stimulus measurements of the constituent single‐colorant samples and the illuminant are obtainable. Related to the new theorems, a formulation is derived for the calculation of the bounds of realistic colorants whose spectral transmittances are represented by weighted combinations of basic functions. By solving the formulation, numerical illustrations are provided for various conditions. The results contribute toward a comprehensive modeling of subtractive color mixture. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 354–362, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.
Orbital Magnetization in Extended Systems
Authors: Resta R. , Ceresoli Davide , Thonhauser T. , Vanderbilt David
Published: August 2005

While the orbital magnetic dipole moment of any finite sample is well‐defined, it becomes ill‐defined in the thermodynamic limit as a result of the unboundedness of the position operator. Effects due to surface currents and to bulk magnetization are not easily disentangled. The corresponding electrical problem, where surface charges and bulk polarization appear as entangled, was solved about a decade ago by the modern theory of polarization, based on a Berry phase. We follow a similar path here, making progress toward a bulk expression for the orbital magnetization in an insulator represented by a lattice‐periodic Hamiltonian with broken time‐reversal symmetry. We therefore limit ourselves to the case where the macroscopic (i.e. cell‐averaged) magnetic field vanishes. We derive an expression for the contribution to the magnetization arising from the circulating currents internal to the bulk Wannier functions, and then transform to obtain a Brillouin zone integral involving the occupied Bloch orbitals. A version suitable for practical implementation in discretized reciprocal space is also derived, and the gauge invariance of both versions is explicitly shown. However, tests on a tight‐binding model indicate the presence of additional edge currents, and it remains to be determined whether these can be related to the bulk band structure.
Four correlates of complex behavioral networks: Differentiation, behavior, connectivity, and compartmentalization: Carving networks at their joints
Authors: Changizi Mark A. , He Darren
Published: August 2005

Some of the most complex networks are those that (i) have been engineered under selective pressure (either economic or evolutionary), and (ii) are capable of eliciting network‐level behaviors. Some examples are nervous systems, ant colonies, electronic circuits and computer software. Here we provide evidence that many such selected, behavioral networks are similar in at least four respects. (1) Differentiation: Nodes of different types are used in a combinatorial fashion to build network structures through local connections, and networks accommodate more structure types via increasing the number of node types in the network (i.e., increasing differentiation), not via increasing the length of structures. (2) Behavior: Structures are themselves combined globally to implement behaviors, and networks accommodate a greater behavioral repertoire via increasing the number of lower‐level behavior types (including structures), not via increasing the length of behaviors. (3) Connectivity: In order for structures in behavioral networks to combine with other structures within a fixed behavior length, the network must maintain an invariant network diameter, and this is accomplished via increasing network connectivity in larger networks. (4) Compartmentalization: Finally, for reasons of economical wiring, behavioral networks become increasingly parcellated. Special attention is given to nervous systems and computer software, but data from a variety of other behavioral selected networks are also provided, including ant colonies, electronic circuits, web sites and businesses. A general framework is introduced illuminating why behavioral selected networks share these four correlates. Because the four above features appear to apply to computer software as well as to biological networks, computer software provides a useful framework for comprehending the large‐scale function and organization of biological networks. © 2005 Wiley Periodicals, Inc. Complexity 10: 13–40, 2005
Electron Kinetics and Self‐Consistent Description of Inhomogeneous and Nonstationary Plasmas
Authors: Loffhagen D. , Arndt S. , Sigeneger F. , Uhrlandt D. , Winkler R.
Published: August 2005

A brief introduction into the progress of the analysis of the electron kinetics and the self‐consistent description of inhomogeneous and nonstationary plasmas is given. The spectrum of problems treated by electron kinetic studies as well as by the overall description of non‐isothermal plasmas is briefly characterized. Main aspects of the analyses are outlined and the progress reached in recent years in the framework of the collaborative research activities of the Sonderforschungsbereich 198 “Kinetics of partially ionized plasmas” is illustrated by topical kinetic study and self‐consistent modelling results of some selected problems. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Generation of Highly Charged and Energetic Ions From the Interaction of Strong Laser Pulses with Coinage Metal Clusters
Authors: Radcliffe P. , Döppner T. , Schumacher M. , Teuber S. , Tiggesbäumker J. , Meiwes‐Broer K.‐H.
Published: August 2005

Plasmon–enhanced ionization of free coinage metal clusters is studied under intense laser field conditions. The charging and the subsequent Coulomb explosion results in huge recoil energies of the atomic fragment ions. In a charge‐resolved measurement it is found that the maximum kinetic energy scales roughly linear with the charge state. The ionization efficiency could strongly be enhanced when the pulse structure is adapted to the expansion dynamics of the cluster Coulomb explosion. Irradiation with stretched laser pulses as well as with dual pulses show that atomic charge states up to Cu10+, Ag15+ and Au15+ are generated whenever the plasmon mode of the cluster can be successfully excited. The charging enhancement when using dual pulses gives evidence that continuous heating is not necessary in order to get maximum energy absorption. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An upwind finite element scheme for high‐Reynolds‐number flows
Authors: Tabata Masahisa , Fujima Shoichi
Published: August 2005

A new upwind finite element scheme for the incompressible Navier‐Stokes equations at high Reynolds number is presented. The idea of the upwind technique is based on the choice of upwind and downwind points. This scheme can approximate the convection term to third‐order accuracy when these points are located at suitable positions. From the practical viewpoint of computation, the algorithm of the pressure Poisson equation procedure is adopted in the framework of the finite element method. Numerical results of flow problems in a cavity and past a circular cylinder show excellent dependence of the solutions on the Reynolds number. The influence of rounding errors causing Karman vortex shedding is also discussed in the latter problem.
A linearized Riemann solver for the steady supersonic Euler equations
Authors: Toro Eleuterio F. , Chou Cheng‐Chiang
Published: August 2005

A very simple linearization of the solution to the Riemann problem for the steady supersonic Euler equations is presented. When used locally in conjunction with the Godunov method, computing savings by a factor of about four relative to the use of exact Riemann solvers can be achieved. For severe flow regimes, however, the linearization loses accuracy and robustness. We then propose the use of a Riemann solver adaptation procedure. This retains the accuracy and robustness of the exact Riemann solver and the computational efficiency of the cheap linearized Riemann solver. Numerical results for two‐ and three‐dimensional test problems are presented.
Role for CXCR2 and CXCL1 on glia in multiple sclerosis
Authors: Omari Kakuri M. , John Gareth , Lango Richard , Raine Cedric S.
Published: August 2005

As part of a need to understand myelin repair mechanisms, molecular pathways underlying oligodendrocyte behavior and central nervous system (CNS) remyelination are currently key topics in multiple sclerosis (MS). In the present study, we report expression of a chemoattractant receptor of the immune system, the chemokine receptor, CXCR2, on normal and proliferating oligodendrocytes in active MS lesions. Proliferating oligodendrocytes were occasionally associated with reactive astrocytes positive for CXCL1 (GRO‐α), the ligand for CXCR2. CXCL1 expression was not seen on astrocytes in control and normal CNS tissue, while CXCR2 expression was constitutive on oligodendrocytes. At the functional level, following stimulation with the proinflammatory cytokine, interleukin‐1β (IL‐1β), we found high‐level synthesis of CXCL1 by human fetal astrocytes in vitro. In contrast, human oligodendrocytes in culture expressed the receptor, CXCR2, constitutively. We propose that the concurrence of CXCR2 on oligodendrocytes and induced CXCL1 on hypertrophic astrocytes in MS provides a novel mechanism for recruitment of oligodendrocytes to areas of damage, an essential prerequisite for lesion repair in this devastating human condition. © 2005 Wiley‐Liss, Inc.
Cell sheet detachment affects the extracellular matrix: A surface science study comparing thermal liftoff, enzymatic, and mechanical methods
Authors: Canavan Heather E. , Cheng Xuanhong , Graham Daniel J. , Ratner Buddy D. , Castner David G.
Published: August 2005

This work compares the removal of bovine aortic endothelial cell (BAEC) monolayers via 1) low‐temperature liftoff from a “smart polymer,” plasma polymerized poly(N‐isopropyl acrylamide) (ppNIPAM), 2) enzymatic digestion, and 3) mechanical dissociation from ppNIPAM surfaces. We examine the surfaces after cell removal by using X‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS), immunostaining, and cell adhesion assay. Immunoassay results indicate that low‐temperature liftoff nondestructively harvests the cell sheet and most of the underlying extracellular matrix (ECM), whereas enzymatic digestion and mechanical dissociation are damaging to both the cells and ECM. XPS results indicate that amide and alcohol groups attributed to proteins in the ECM are present on postliftoff surfaces. Principal component analysis (PCA) of ToF‐SIMS data indicates that molecular ion fragments of amino acids are present on postliftoff surfaces. Finally, a cell adhesion assay seeding new cells on surfaces from which an initial layer of cells was removed via each of the three methods indicates that liftoff and mechanical dissociation leave behind surfaces that better promote cell adhesion. We conclude that the removal of BAEC cells via low‐temperature liftoff from ppNIPAM‐treated surfaces is less damaging to the ECM proteins remaining at the surface than the other methods. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Chitosan–alginate as scaffolding material for cartilage tissue engineering
Authors: Li Zhensheng , Zhang Miqin
Published: August 2005

Tissue compatibility of chitosan–alginate scaffolds was studied in vitro in terms of cell morphology, proliferation, and functionality using HTB‐94 cells. The scaffold has an interconnected 3D porous structure, and was fabricated by thermally induced phase separation followed by freeze drying. Cell proliferation on the chitosan–alginate scaffold was found to be faster than on a pure chitosan scaffold. After cell culture for 2 weeks in vitro, the cells on the chitosan scaffold gradually assumed a fibroblast‐like morphology while the cells on the chitosan–alginate scaffold retained their spherical morphology throughout the period of study. SDS‐PAGE electrophoresis and Western blot assays for proteins extracted from cells grown on scaffolds indicated that production of cartilage‐specific collagen type II, a marker for chondrocytic phenotype, increased from week 2 to week 3 on the chitosan–alginate scaffold but decreased on the chitosan scaffold. This study suggested that chitosan–alginate scaffolds promote cell proliferation, enhance phenotype expression of HTB‐94 chondrocytes, and may potentially serve as an improved alternative to chitosan scaffolds for cartilage tissue engineering. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
The effect of hyaluronic acid with different molecular weights on collagen crosslink synthesis in cultured chondrocytes embedded in collagen gels
Authors: Abe Masashi , Takahashi Masaaki , Nagano Akira
Published: August 2005

Hyaluronic acid (HA) is a component of the extracellular matrix of cartilage and has various effects on three‐dimensional cultured chondrocytes. We measured Pyridinoline (Pyr), which is a crosslink of collagen in cultured chondrocyte–collagen composites treated with HA of different molecular weights to investigate the effects of the various molecular weights on collagen crosslink synthesis. The control group was collagen gel without cells; group N was treated without HA; and the others were treated with HA with an average molecular weight of 2.3 ×106 Da (group H), 8.0 ×105 Da (group M), and 2.3 ×104 Da (group L). In the control group, the Pyr content decreased, at week 4, being one‐tenth that of preculture levels. In groups H and M, it was significantly greater than that in groups L and N at week 4. Pyr/hydroxyproline, which indicates the concentration of Pyr per collagen, decreased greatly in the control group at week 3. In groups H and M, it was significantly higher than that in groups L and N at week 4 and increased to 80 and 76% of normal rabbit articular cartilage, respectively. The concentration of Pyr per collagen in cultured chondrocyte–collagen composites was similar to that of normal articular cartilage in vivo, and higher molecular weight HA may have a greater effect on the maturation of collagen in the composite. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Processing of radial fast spin‐echo data for obtaining T2 estimates from a single k‐space data set
Authors: Altbach Maria I. , Bilgin Ali , Li Zhiqiang , Clarkson Eric W. , Trouard Theodore P. , Gmitro Arthur F.
Published: August 2005

Radially acquired fast spin‐echo data can be processed to obtain T2‐weighted images and a T2 map from a single k‐space data set. The general approach is to use data at a specific TE (or narrow TE range) in the center of k‐space and data at other TE values in the outer part of k‐space. With this method high‐resolution T2‐weighted images and T2 maps are obtained in a time efficient manner. The mixing of TE data, however, introduces errors in the T2‐weighted images and T2 maps that affect the accuracy of the T2 estimates. In this work, various k‐space data processing methods for reconstructing T2‐weighted images and T2 maps from a single radial fast spin‐echo k‐space data set are analyzed in terms of the accuracy of T2 estimates. The analysis is focused on the effect of image artifacts, object dependency, and noise on the T2 estimates. Results are presented in computer‐generated phantoms and in vivo. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
19F MR imaging of ventilation and diffusion in excised lungs
Authors: Jacob Richard E. , Chang Yulin V. , Choong Cliff K. , Bierhals Andy , Zheng Hu Ding , Zheng Jie , Yablonskiy Dmitriy A. , Woods Jason C. , Gierada David S. , Conradi Mark S.
Published: August 2005

Perfluorinated gases, particularly C2F6, are potentially suitable alternatives to hyperpolarized noble gases for pulmonary airspace spin density and diffusion MRI. This work focuses mainly on 19F imaging of C2F6 gas in healthy and emphysematous explanted lungs, avoiding regulatory issues of human in vivo measurements. Three‐dimensional gradient echo and spin echo spin density images of human lungs can be made in 10 s with adequate signal‐to‐noise, demonstrating the feasibility for breathing dynamics to be captured during a succession of short breath holds. As expected, the spin echo images have much smaller susceptibility artifacts than the gradient echo images. 19F and 3He images of the same lungs are compared. The apparent diffusion coefficient (ADC) of C2F6 is sensitive to restrictions imposed by the lung microstructure: the average ADC is measured to be 0.018 cm2/s in healthy lungs versus 0.031 cm2/s in emphysematous lungs at a diffusion time Δ = 2.2 ms. The low free diffusivity of pure C2F6 (D0 = 0.033 cm2/s) places it in a regime where the ADC measurement allows the surface‐to‐volume ratio to be determined in each voxel, a potentially valuable quantitative characterization of regional lung tissue destruction in emphysema. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Chronic inflammatory demyelinating polyradiculoneuropathy with tumefactive central demyelination
Authors: Krivickas Lisa S. , Hochberg Fred H. , Freeman Stefanie
Published: August 2005

A 46‐year‐old man with a 1‐year history of distal paresthesias and mild distal weakness subacutely developed paralysis of the left hand. Electrodiagnostic evaluation revealed a demyelinating peripheral neuropathy that met criteria for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Magnetic resonance imaging of the brain revealed a mass that enhanced with contrast, but revealed focal myelin loss with intense macrophage activity and axonal preservation on biopsy. The mass and hand weakness improved following steroid therapy. The combination of CIDP and central demyelination with mass effect broadens the spectrum of demyelinating disease in association with CIDP. Muscle Nerve, 2005
On Garg's solution of Biot's equations for wave propagation in a one‐dimensional fluid‐saturated elastic porous solid
Authors: Hong S. J. , Sandhu Ranbir S. , Wolfe William E.
Published: August 2005

Garg's approximate analytical solutions of Biot's equations for wave propagation in a fluid‐saturated elastic porous solid of infinite extent subjected to a velocity boundary condition of a Heaviside function at one end are examined for small and large drag. Garg's approximations were apparently introduced to facilitate exact inversion of Laplace transforms of certain quantities. The approximate solutions are compared with carefully evaluated numerical inverses of the Laplace transform solutions for different soils with widely varying properties. It is seen that for most soils (clays, silts and, sands) the error in Garg's approximate solutions in insignificant, and the solutions can be used as benchmarks for verifying numerical analysis procedures such as finite element codes.
Material instability for drained and undrained behaviour. Part 2: Combined uniform deformation and shear‐band generation
Authors: Molenkamp F.
Published: August 2005

To increase the insight into the phenomenon of liquefaction a theoretical study has been performed of material instability for undrained behaviour. Material instability concerns the instability of an equilibrium state of an infinite homogeneous solid for both uniform deformation and shear‐band generation. In a companion paper shear‐band generation has been considered. In this paper the case of uniform deformation is elaborated and combined with the previous results. It can be concluded that instability occurs sooner for increasing contraction and decreasing drainage. For zero plastic volume change and decreasing drainage the mode of instability changes from drained shear‐band generation to undrained uniform deformation. For contractant materials the instability of undrained behaviour is mainly due to uniform deformation.
Numerical analysis of sedimentation and consolidation by the moving finite element method
Authors: Shodja Hossein M. , Feldkamp Joseph R.
Published: August 2005

Traditionally, sedimentation and self‐weight consolidation have been viewed as physically distinct processes requiring separate treatment. Relatively recently, Pane and Schiffman1 and also Philip and Smiles2 have suggested that the two processes may be described by a single partial differential equation, essentially that of Gibson et al.3 The former suggests a modification of Terzaghi's effective stress principle while the paper by Philip and Smiles suggests that a suitable modelling of material properties is sufficient. We have adopted the latter approach by allowing for the compressibility of the material in question to change abruptly from finite values to infinity in the so‐called transition region which delineates that portion of space where effective stress is zero from that where effective stress in non‐zero. This procedure gives rise to serious difficulties when trying to solve the governing partial differential equation numerically. These difficulties are circumvented by using a relatively new numerical technique known as the Moving Finite Element (MFE) method. The MFE method is especially effective in solving problems having solutions that characteristically exhibit shock‐like structure. The modelling of sedimentation and self‐weight consolidation from a single governing model is an ideal candidate for MFE due to the abrupt, almost discontinuous change in void ratio displayed in the transition region.
Thermodynamical approach for CamClay‐family models with Roscoe‐type dilatancy rules
Authors: Modaressi Hormoz , Laloui Lyesse , Aubry Denis
Published: August 2005

The CamClay model has been extensively used in numerous research programmes for constitutive modelling in Soil Mechanics during the past quarter of a century. Several derivations of this model are now available and routinely used for numerical simulations in the geomechanical engineering field. However, to the authors' knowledge the thermodynamical basis of this model in its original form has never been established, at least in a modern thermodynamics framework. The thermodynamics principle proposed by Ziegler is very expedient for this purpose as the non‐associated flow rule may be considered. This approach is applied to the CamClay model with the Roscoe dilatancy rule. A dissipation function and free energy are specified in terms of kinematic variables (i.e. state and internal variables), and the material response is derived entirely from these functions.
Influence of subsurface fractures on surface deformation of an elastic half‐space
Authors: Wang G. , Dusseault M. B. , Pindera J. T. , Rothenburg L.
Published: August 2005

The paper presents a solution for calculation of the surface uplift field of a semi‐infinite elastic solid embedded with a pressurized elliptical crack oriented at any angle, and at any depth. The results presented are those for a uniform pressure loading on the crack face, simulating a static pressurized hydraulic fracture, but the mathematical technique developed can be extended directly to non‐uniform normal loads or general shear loads in the form of a polynomial up to the third order. The result of a special case of the new solution, where the crack is penny shaped and parallel to the free surface, is compared with results from Sun's solution and from experiments which were designed and performed by the authors. The experiments involved pressurization of a penny‐shaped crack in a polyurethane material which is linear elastic under low stresses, and measurement of surface deformation by holographic interferometry and Fizeau interferometry. The correspondence between theory and experiment is excellent.
Non‐linear structural analysis by dynamic relaxation
Authors: Brew J. S. , Brotton D. M.
Published: August 2005

Dynamic relaxation, an iterative method for use with digital computers, is described and is shown to be suitable for the solution of a system of linear equations and in particular for such problems derived from structural frame analysis. It is further shown that the method may be modified to include non‐linear equations relating to these problems.

Some specific examples of linear and non‐linear solutions are given and comparisons are made with another computer method which performs the same tasks.
Calculation of eigenvalues of the Helmholtz equation by an integral equation
Authors: de Mey G.
Published: August 2005

A method is presented to calculate the eigenvalues of the Helmholtz equation Δ2ø + k2ø = 0 in a two‐dimensional area when ø vanishes on the boundary. The method is based on an integral equation, which can be easily solved numerically. Results obtained for circular and rectangular geometries are also given and compared to the exact values.
Automatic generation of triangular grid: I—subdivision of a general polygon into convex subregions. II—triangulation of convex polygons
Authors: Bykat A.
Published: August 2005

One of the integral parts of any finite element procedure is the subdivision of a finite dimensional region into a finite number of non‐overlapping subregions. An algorithm for subdivision of 2‐dimensional polygons into triangular subregions is presented here. The algorithm consists conceptually of two steps. In the first step the region is subdivided into convex subregions; In the second step the convex subregions are further subdivided into triangular elements.
Mixed finite element formulation for geometrically non‐linear analysis of shells of revolution
Authors: Tottenham H. , Barony S. Y.
Published: August 2005

A Finite Element formulation for the axisymmetrical analysis of rotational shells with geometric non‐linearity is developed, using a mixed finite element model of a curved rotational shell type, the two global components of displacement (ur, uz) and the two stress couples (Mr, MtH) being the free and independent unknowns of the problem. The prescribed geometry at every nodal circle comprises the co‐ordinates and meridional slope angle and curvature. Newton‐Raphson Iteration is used in solving the non‐linear system of equations. Circular plates and a spherical cap are used as examples to test the formulation; good results were achieved which are presented graphically in comparison to the analytical solution.
A finite element method for Burgers' equation in hydrodynamics
Authors: Arminjon Paul , Beauchamp Cladue
Published: August 2005

A Finite Element Method using rectangular elements is applied to solve Burgers' non‐linear equation in one space dimension. The non‐linear algebraic equations thus obtained are solved by an iteration which is equivalent to the generalized Newton method. Numerical experiments indicate that the order of accuracy is equal to 2. In two space dimensions, the method is more efficient than other methods we have tested.
Hybrid stress finite element analysis of bending of a plate with a through flaw
Authors: Rhee H. C. , Atluri S. N.
Published: August 2005

A hybrid stress finite element procedure for the solution of bending stress intensity factors of a plate with a through‐the‐thickness crack is presented. Reissner's sixth‐order plate theory including the effects of transverse shear deformation is used. The dominant singular crack tip stress field is embedded in the crack tip singular elements and only regular polynomial functions are assumed in the far field elements. The stress intensity factors can be calculated directly from the crack tip singular stress solution functions. The effects of the plate thickness, the ratio between the crack size and the inplane dimension of the plate, and the singular element size on the stress intensity factor solution are investigated.

The effects of the explicit enforcement of traction‐free conditions along crack surfaces, which are the natural boundary conditions in the present hybrid stress finite element model, are also investigated. The numerical results of bending of a plate with a straight central crack compare favourably with analytical solutions. It is also found that the explicit enforcement of traction‐free conditions along crack surfaces is mandatory to obtain meaningful results for the Mode I type of bending stress intensity factor.
Dual analysis of plane stress problems by commonly based finite elements
Authors: Harvey John W.
Published: August 2005

Finite element models for linear elastic plane stress problems which provide, alternatively, a completely compatible displacement field or a precisely equilibrated stress field are developed. The basis for both models is a biquintic interpolation polynomial representing Airy's stress function over a triangular region. The polynomial coefficients are modified and grouped to establish compatibility while retaining equilibrium within each element. Nodal kinematic parameters are selected and matched to the stress function for the compatible (modified stiffness) model, while nodal stress function parameters are chosen for the equilibrium (modified flexibility) model. Constraints on the global freedoms, enforced by Lagrange multipliers, are introduced to augment nodal connectivity in establishing interelement compatibility in the ‘stiffness’ model and uniform stress transmission in the ‘flexibility’ model. Appropriate boundary conditions are formed for each model. Numerical solutions are obtained and assessed.
Added mass computations by integral equation methods
Authors: Ousset Y. , Sayhi M. N.
Published: August 2005

This paper presents boundary integral equation procedures for calculating the added mass matrix required to determine hydroelastic vibrational modes of tanks or immersed structures. The liquid is assumed inviscid and incompressible and no surface waves are admitted. Two symmetric variational formulations of the boundary integral equation are derived, including the free surface condition and possible conditions of symmetry. These are approximated by a curved finite element method and numerical results are presented for an axisymmetric tank, immersed cantilever plates and a three‐dimensional fuel storage container.
Double noding technique for mixed mode crack propagation studies
Authors: Liaw B. M. , Kobayashi A. S. , Emery A. F.
Published: August 2005

A simple dynamic finite element algorithm for analysing a propagating mixed mode crack tip is presented. A double noding technique, which can be easily incorporated into existing dynamic finite element codes, is used together with a corrected Ĵ integral to extract modes I and II dynamic stress intensity factors of a propagating crack. The utility of the procedure is demonstrated by analysing test problems involving a mode I central crack propagating in a plate subjected to uniaxial tension, a stationary slanted central crack in a plate subjected to uniaxial inpact loading and an extending slanted‐edge crack in plate subjected to uniaxial tension.
Partitioned rational Runge Kutta for parabolic systems
Authors: Liu Wing Kam , Belytschko Ted , Zhang Yi Fei
Published: August 2005

A new family of coupled time integration operators of different orders is developed. It permits different time integration operators to be used simultaneously in various regions of the model. This approach has the advantage of applying a very accurate time integrator, such as Runge Kutta method of order two to four, to the local nonlinear region of interest and a simple time integrator, such as the implicit–explicit or mixed time implicit–explicit method of order one, for the remaining region. The computer implementation aspects, stability analysis as well as the numerical evaluations of these new methods are presented. This is another attractive addition to the repertoire of time integration methods.
FEM‐analysis of transverse vibrations of an axially moving membrane immersed in ideal fluid
Authors: Niemi J. , Pramila A.
Published: August 2005

Transverse vibrations of an axially moving (travelling in its own plane) membrane submerged in ideal fluid are analysed using the FEM. The discrete equations differ from the equations of the common coupled problem in that there appear two additional inertia terms due to the convective acceleration. The effect of the density of the element mesh, the effect of the truncation distance and the effect of various lumping techniques on the accuracy of the results are studied. The FEM‐results are compared with available analytical and experimental results. The agreement seems to be rather good.
Remarks on computational magnetostatics
Authors: Sussman M. M.
Published: August 2005

A two‐scalar‐potential formulation for magnetostatic computations has been recommended4 based on a comparative study of several different formulations in terms of their accuracy and efficiency. A different study3 challenged this recommendation. It is the purpose of this report to present results which confirm the practical necessity for the two‐potential formulation.

The method used for the present study was to construct a simplified computer program designed to easily compare the alternative methods. This program uses the finite element method on a geometry suited for analysis of the ‘bifiliar conductor’ problem treated in both studies mentioned above. In this program, the alternative formulations are implemented with a great deal of common code. In particular, the input, stiffness matrix, matrix solution and editing routines are common to both formulations, with differences appearing only in the source terms for the stiffness matrix equation. The known analytic solution to this particular problem provides a reference with which the computed solutions is compared. The main conclusion of this study of the ‘bifiliar conductor’ problem is that for a given choice of mesh, the two‐potential formulation yields significantly more accuracy than the reduced‐potential formulation.