Skeletal Frame Research Articles

A Matter of Character: Vasistha and Aristotle on moral development

The author of the Yogavīsistha Mahīrīmī yana has liberation (moksa) foremost on her or his mind and this focus appears to relegate virtue (dharma) to poor relation status. Yet, Rīma's question to Vasistha is, 'How should one live in this world?' This signals a strongly ethical stance and opens another avenue of exploration; the possibility that the teachings on the realisation of liberation are concomitant with the teachings regarding the embodiment of virtue. The aim of this paper is to flesh out the admittedly skeletal frame of virtue by comparing the theories in the Yogavīsistha with Aristotle's elaboration of virtue in the Nicomachean Ethics. I argue that, in spite of fundamental metaphysical differences between the two philosophers, the stages of moral development described in the Yogavīsistha harmonise with Aristotle's theories and provide insights into problems that arise in Aristotle's work.

Analysis of silt behavior induced by water waves

Based on the weak non-elastic porous model, the expressions of pore pressure, effective stress and displacements of soil skeletal frame and pore water have been deduced for a finite depth seabed. The distributions of several physical parameters have been analyzed for three kinds of marine sediment, including pore pressure, effective stress, stress angle, displacement of skeletal frame and pore fluid, and the variations of elastic waves with wave period. According to the experimental results, the resonant phenomena in the silt bed and the mechanism underlying such events have been discussed. It is proposed that the existence of a stiff soil layer inside the silt bed is a necessary condition for resonance to occur, and the possible location of resonance can be forecasted.

Using an analytical solution to estimate the subsidence risk caused by ASR applications

Abstract Land subsidence, due to the net compression of one or more semi-pervious clay beds, can be induced by the application of aquifer storage and recovery (ASR) technology. ASR technology involves periodically pumping and injecting water from or into adjacent aquifers for various purposes. In order to estimate the potential risk of aquifer system deformation in response to an injecting-pumping scheme, an analytic solution for the one-dimensional case (a sandwich model) is solved. The solution is analyzed for a unit column of an idealized compressible semipervious layer. A governing equation is invoked that is expressed directly in terms of the vertical displacement of the skeletal frame (Helm, 1987). For simplicity, the saturated aquifer system is assumed to behave like poroelastic material (both recoverable and nonrecoverable). The two idealized aquifers (one above the modeled semi-confining bed and the other beneath) can be pumped independently of each other. Analytical solutions are found for subsidence in response to selected stress/pumping patterns. Results from the analytic solution are applied in order to estimate and predict the potential risk of land subsidence due to ground-water withdrawal and injection, and to provide a first-estimate type of guideline for city and regional planning and the exploration of water resources.

Wave propagation, stress relaxation, and grain-to-grain shearing in saturated, unconsolidated marine sediments

A linear theory of wave propagation in saturated, unconsolidated granular materials, including marine sediments, is developed in this article. Since the grains are unbonded, it is assumed that the shear rigidity modulus of the medium is zero, implying the absence of a skeletal elastic frame. The analysis is based on two types of shearing, translational and radial, which occur at grain contacts during the passage of a wave. These shearing processes act as stress-relaxation mechanisms, which tend to return the material to equilibrium after the application of a dynamic strain. The stress arising from shearing is represented as a random stick-slip process, consisting of a random succession of deterministic stress pulses. Each pulse is produced when micro-asperities on opposite surfaces of a contact slide against each other. The quantity relevant to wave propagation is the average stress from all the micro-sliding events, which is shown to be a temporal convolution between the deterministic stress, h(t), from a single event and the probability, q(t), of an event occurring between times t and t+dt. This probability is proportional to the velocity gradient normal to the tangent plane of contact between grains. The pulse shape function, h(t), is derived by treating the micro-sliding as a strain-hardening process, which yields an inverse-fractional-power-law dependence on time. Based on two convolutions, one for the stress relaxation from translational and the other from radial shearing, the Navier–Stokes equation for the granular medium is derived. In a standard way, it is split into two equations representing compressional and shear wave propagation. From these wave equations, algebraic expressions are derived for the wave speeds and attenuations as functions of the porosity and frequency. Both wave speeds exhibit weak, near-logarithmic dispersion, and the attenuations scale essentially as the first power of frequency. A test of the theory shows that it is consistent with wave speed and attenuation data acquired recently from a sandy sediment in the Gulf of Mexico during the SAX99 experiment. If dispersion is neglected, the predicted expressions for the wave speeds reduce to forms which are exactly the same as those in the empirical elastic model of a sediment proposed by Hamilton. On this basis, the concept of a “skeletal elastic frame” is interpreted as an approximate, but not equivalent, representation of the rigidity introduced by grain-to-grain interactions.

Body mass prediction from skeletal frame size in elite athletes.

Body mass can be estimated from measures of skeletal frame size (stature and bi-iliac (maximum pelvic) breadth) fairly accurately in modern human populations. However, it is not clear whether such a technique will lead to systematic biases in body mass estimation when applied to earlier hominins. Here the stature/bi-iliac method is tested, using data available for modern Olympic and Olympic-caliber athletes, with the rationale that these individuals may be more representative of the general physique and degree of physical conditioning characteristic of earlier populations. The average percent prediction error of body mass among both male and female athletes is less than 3%, with males slightly underestimated and females slightly overestimated. Among males, the ratio of shoulder to hip (biacromial/bi-iliac) breadth is correlated with prediction error, while lower limb/trunk length has only a weak inconsistent effect. In both sexes, athletes in "weight" events (e.g. , shot put, weight-lifting), which emphasize strength, are underestimated, while those in more endurance-related events (e.g., long distance running) are overestimated. It is likely that the environmental pressures facing earlier hominins would have favored more generalized physiques adapted for a combination of strength, speed, agility, and endurance. The events most closely approximating these requirements in Olympic athletes are the decathlon, pentathlon, and wrestling, all of which have average percent prediction errors of body mass of 5% or less. Thus, "morphometric" estimation of body mass from skeletal frame size appears to work reasonably well in both "normal" and highly athletic modern humans, increasing confidence that the technique will also be applicable to earlier hominins.

The performance of composite-steel-framed building structures in fire

This paper outlines the behaviour of steel and composite structures in fire, and reviews recent research developments in this field, and describes the practical implications for designers. The initial focus is on isolated beams, columns and slabs. The effect of structural continuity afforded by skeletal frame construction is considered, and the importance of connection stiffness discussed. Finally, the importance of considering the behaviour of complete three-dimensional building structures is demonstrated, and the direction suggested by this major research area is outlined.

Using the Biot theory to establish a baseline geoacoustic model for seafloor sediments

By modeling the soft, fine-grained sediments of Eckernförde Bay, Germany, as porous viscoelastic materials filled with a viscous fluid, the Biot theory is used to establish a baseline geoacoustic model that is useful as a starting point for studies of scattering and other phenomena caused by the introduction of free gas into the sediment. The basic parameters of the model are derived from a wide variety of field measurements made during the Coastal Benthic Boundary Layer research program. The low permeability revealed by these measurements indicated that the overall fluid mobility would be small and therefore it would be necessary to include the effects of local fluid motion in “hidden” coordinate systems in order to model the dispersion and attenuation that is observed over a wide fre-quency range. This was accomplished by using a very general viscoelastic model (Cole–Cole model) to describe the response of the skeletal frame in a water environment. By adjusting the three free parameters of this model it was possible to match both overall attenuation and velocity in both high- and low-frequency ranges, however, because of the fact that compressional attenuation and velocity were only measured at two relatively high frequencies and shear wave attenuation determined only at low frequency, it is not clear whether the best rheological model was chosen to model the skeletal frame. This suggests that more specially designed experimental studies are desirable if the objective is to define the most general baseline model, applicable over a wide frequency range.

Viscous drag, driving forces, and their reduction to Darcy's Law

On the basis of the conservation of momentum for pore water flow, a new relation between drag and driving forces is developed for flow within a saturated aquifer. Such a relation inherently includes inertial terms of both the solid phase and the fluid phase that play an important role under dynamic conditions (e.g., earthquakes) and under some transient conditions (e.g., aquifer pumping). For laminar flow of a fluid relative to the skeletal frame a new relation is reached by simplification from the more general case. The Darcy‐Gersevanov law and Darcy's law are found to be special cases that result from further simplifications.

Scattering and refracting of plane strain wave by a cylindrical inclusion in fluid-saturated soils

The problems involving scattering and refracting of plane strain wave by a cylinder in fluid-saturated soils are studied in this paper. The theoretical solutions for the amplitudes of scattering and refracting are derived on the basis of modified Biot’s theory for two-phase medium in engineering, in which the compressibility of soil grains and the viscous coupling effect between the skeletal frame and the pore fluid are taken into account. Moreover, the amplitude equations of potential function are presented when the fluid-saturated soil cylindrical inclusion is degenerated into cylindrical cavity, rigid cylinder, single phase elastic cylinder and single phase fluid cylinder.

Measuring parameters that control acoustic propagation in granular sediments near the seafloor

Propagation of acoustic waves in granular sediments near the water-sediment interface is controlled by a number of parameters such as fluid and grain compressibility, permeability, and the compressibility and shear stiffness of the skeletal frame in a water environment. A new experimental technique for evaluating several of these properties is described wherein a cylindrical, water-saturated sample is subjected to vertical, steady-state fluid flow. By controlling the hydraulic gradient, any desired vertical, effective stress may be generated and acoustic measurements then made across the diameter. When the effective stress is reduced to zero, acoustic measurements yield the compressibility of the grains, whereas at nonzero effective stress levels, it is possible to assess the effects of depth of embedment which causes changes in the compressibility and stiffness of the frame. Finally, by measuring the flow rate at each gradient, a direct evaluation of permeability is made. Preliminary measurements agree with most historical evaluations of these parameters suggesting that some recent work which challenges the traditional values is in error. [Work supported by ONR, code 321OA.]

Theory of compressional and shear waves in fluidlike marine sediments

An unconsolidated, saturated marine sediment consists of a more or less loose assemblage of mineral grains in contact, with seawater in the interstices. It is postulated that the two-phase medium possesses no skeletal frame, implying that the elastic rigidity modulus of the material is zero. A theory of wave propagation in such a sediment is developed, in which the medium is treated as a fluid that supports a specific form of intergranular dissipation. Two important equations emerge from the analysis, one for compressional wave propagation and the second describing transverse disturbances. For the type of dissipation considered, which exhibits hysteresis or memory, the shear equation admits a wavelike solution, and is thus a genuine wave equation, even though the sediment shows no elastic rigidity. In effect, the medium possesses a “dissipative” rigidity, which is capable of supporting shear. This behavior is distinct from that of a viscous fluid, for which the shear equation is diffusionlike in character, giving rise to critically damped disturbances rather than propagating waves. The new theory predicts an attenuation coefficient for both compressional and shear waves that scales with the first power of frequency, in accord with published data. The wave theory is combined with a model of the mechanical properties of marine sediments to yield expressions relating the compressional and shear wave speeds to the grain size, the porosity, and the density of the medium. These expressions show compelling agreement with a number of measurements from the literature, representing a variety of sediment types ranging from clay to coarse sand.

Buried Point Source in a Poroelastic Half-Space

The problem under consideration is to determine the motion of a poroelastic half-space produced by a buried point source with arbitrary time variation. The method followed is to generate the associated Green's functions as a superposition of the singular solution corresponding to the inhomogeneous problem for the whole space plus a contribution representing relevant effects due to the presence of the free surface. The mathematical approach is based on integral transform techniques: Fourier transform with respect to the time and Hankel transform with respect to the space. The Green's functions for the displacement fields (solid and pore fluid motion respectively) show additional integratable singularities arising from Rayleigh poles and by eight branch points resulting from combinations of three radicals containing the three fundamental wave numbers of poroelastic propagation. Recognizing that the branch points and poles are complex valued as a result of dissipation by the skeletal frame as well as viscous...

Extended anterior subcranial approach for skull base tumors: long-term results

The extended anterior subcranial approach differs significantly from more traditional surgical approaches to the skull base in that it allows a broad inferior access to the anterior skull base planes with tumor exposure from below rather than via the transfrontal route. The authors initially used the subcranial approach in 1978 for the treatment of high-velocity skull base trauma and certain craniofacial anomalies. In 1980 they expanded the indications to include the combined neurosurgical-otolaryngological resection of various skull base tumors. Osteotomy of the frontonasoorbital external skeletal frame provides optimum anterior access to the orbital and sphenoethmoidal planes as well as to the nasal and paranasal cavities while avoiding frontal lobe retraction and the external facial incisions characteristic of transcranial and transfacial approaches. The improved visualization of the anterior skull base and clival-sphenoidal region facilitates en bloc tumor removal, optic nerve decompression, exposure of the medial aspect of the cavernous sinus, and watertight realignment of the anterior cranial base dura. In this report the authors present their experience over the past 13 years with 104 patients who underwent operation via the extended subcranial approach. Because extensive frontal lobe manipulation and external facial incisions are avoided with this approach, intensive care unit and overall hospital stay are reduced, related complications are minimized, and postoperative cosmetic appearance is enhanced. The extended anterior subcranial method is therefore an excellent alternative to traditional transfacial-transcranial skull base approaches for the removal of selected skull base tumors.

On the interaction of water waves and seabed by the porous medium model

The interaction of water waves and seabed is studied by using Yamamoto's model, which takes into account the deformation of soil skeletal frame, compressibility of pore fluid flow as well as the Coulumb friction. When analyzing the propagation of three kinds of stress waves in seabed, a simplified dispersion relation and a specific damping formula are derived. The problem of seabed stability is further treated analytically based on the Mohr-Coulomb theory. The theory is finally applied to the coastal problems in the Lian-Yun Harbour and compared with observations and measurements in soil-wave tank with satisfactory results.

Structure and diversity of oldest sponge-microbe reefs: Lower Cambrian, Aldan River, Siberia

The oldest sponge reef is a small Early Cambrian bioherm at the base of the Tommotian Stage (∼535–540 Ma) in southeast Siberia. The mainly archaeocyath construction may be a response to turbid conditions. Cambrocyathellus bowls fused to create a rigid cavernous frame colonized by cryptic Archaeolynthus and calcified microbes ( Renalcis ). In addition to these constructors and binders, other reef guilds are present: bafflers (other archaeocyaths, spiculate sponges, and hyoliths) and dwellers (hyoliths, mollusks, and many others). This is the oldest known reef possessing an open skeletal frame structure built by animals and a mixed animal-autotroph composition. It provides a blueprint for younger Phanerozoic reefs.

How did the australopithecines walk? A biomechanical study of the hip and thigh of Australopithecus afarensis

Some biomechanical characteristics of the pelvis and lower limb of Australopithecus afarensis (AL, 288-1) are compared with those of modern humans, in an attempt to define the pattern of australopithecine bipedal locomotion. The reconstruction of the pelvic and femoral morphology of AL 288-1 (Schmid, 1983) is used as a basic skeletal frame to infer (1) the loading constraints acting on the supporting hip; and (2) the action of some of the main muscles of the lower limb. The analysis reconstructs the placements of the australopithecine gluteal musculature, in the pattern of African pongids and of Homo . Only the reconstruction of the gluteal musculature on the basis of the pongid pattern is consistent with the bony, structure of the fossil and would have permitted effective movements of bipedalism. Moreover, the results clearly indicate that australopithecine bipedalism differs from that of humans. (1) The extended lower limb of australopithecines would have lacked stabilization during walking; and (2) the lower limb would have shown a greater freedom for motion, which can be interpreted as the retention of a partly arboreal behavior.

The influence of body fat content and bone diameter measurements on body dissatisfaction in adult women

This study investigated the simultaneous influence of various anthropometric factors on body dissatisfaction in adult women while controlling for psychological and behavioral factors known to covary with it. Multiple regression analyses confirmed that neuroticism, skeletal frame size, and percent body fat were positively, and age and physical activity inversely, related to dissatisfaction. Subsequent analyses substituted separate bone diameter measurements in place of the composite frame size variable and found that hip diameter, correcting for fatness, was a more salient factor in the determination of body dissatisfaction than the more general estimate of frame size. In pursuit of the perfect ultra-slender body women are encouraged to diet and exercise for weight loss more than ever before. It appears, however, that anatomical factors that are resistant to change by caloric restriction or physical activity, are a significant influence in the degree to which women report discontent with their body shape.

Body Composition Correlates of Weight Dissatisfaction and Dietary Restraint in Young Women

Previous research found that when Body Mass Index (BMI) was statistically controlled in a multiple regression model, the percentage of body fat accounted for no additional variance in dietary restraint scores among women although, on its own, it was a significant predictor of this variable. These results imply that anatomical factors, besides fatness, influence dieting behaviour. The present study was designed to compare the relative influence on dietary restraint and weight dissatisfaction, of three body composition measures, each of which contributes in a different way to subjective impressions of body size (viz. BMI, body fat content, and skeletal frame size). Measures of emotional reactivity ('neuroticism'), body dissatisfaction, and body focus were also included in the regression model. Results indicated that these psychological variables were strongly and positively related to restraint. Frame size was also a significant predictor of restraint and weight dissatisfaction. In fact, when frame size was controlled in the regression model, neither percentage of body fat nor BMI were able to explain any additional variance in restraint scores. These findings indicate that weight concerns and dieting behaviour are influenced, at least among young women, more by the size of their skeletal structure than their degree of adiposity. The irony of these findings is obvious and disheartening. An anatomical feature which is essentially resistant to change by dieting or exercise appears to be a primary influence in women's weight dissatisfaction and their tendency to diet. It is acknowledged, however, that this relationship may not obtain among very obese women.

New and simple equations to estimate the energy and fat contents and energy density of humans in sickness and health.

Two formulas were derived to estimate the energy content of the human body which use only body mass, total body water by 3H2O dilution space and body minerals assessed by anthropometry. The formulas were tested in a body composition database of 561 patients and 151 normal volunteers using established metabolizable energy values for protein, fat and glycogen. Total body protein was determined by in vivo neutron activation analysis (IVNAA), body water by dilution of tritium and body minerals from skeletal frame size. Body glycogen was assumed to be 14.6% of the mineral component. Body fat was obtained by difference, body mass less the sum of water, protein, minerals and glycogen. The standard deviation in the estimate of body energy content was 30 MJ or 4.1% of the energy content of reference man. Two formulas for body energy content were derived by regression with body mass, total body water and body minerals or height. Two formulas for energy density and formulas for percentage body fat were similarly derived.

Arachnostega n. ichnog. -burrowing traces in internal moulds of boring bivalves (late jurassic, northern Germany)

Burrowing traces in internal moulds of molluscs are described asArachnostega gastrochaenae n. ichnog. n. ichnosp. Currently, the ichnogenus is only known from the Late Jurassic and Recent of Northern Germany. The synecology of its polychaete producers is discussed in detail: they were probably opportunistic detritus-feeders and have to be regarded as infaunal coelobites. The tracemakers were not part of an ecological succession because their activity was facilitated by a sedimentation event. They weakened the skeletal frame but rapid cementation and encrusters inhibited them. Finally, aspects of biostratinomy and fossil diagenesis are sketched.