Morphology Of Fingers Research Articles

Microenvironment driven invasion: a multiscale multimodel investigation.

Cancer is a complex, multiscale process, in which genetic mutations occurring at a subcellular level manifest themselves as functional and morphological changes at the cellular and tissue scale. The importance of interactions between tumour cells and their microenvironment is currently of great interest in experimental as well as computational modelling. Both the immediate microenvironment (e.g. cell-cell signalling or cell-matrix interactions) and the extended microenvironment (e.g. nutrient supply or a host tissue structure) are thought to play crucial roles in both tumour progression and suppression. In this paper we focus on tumour invasion, as defined by the emergence of a fingering morphology, which has previously been shown to be dependent upon harsh microenvironmental conditions. Using three different modelling approaches at two different spatial scales we examine the impact of nutrient availability as a driving force for invasion. Specifically we investigate how cell metabolism (the intrinsic rate of nutrient consumption and cell resistance to starvation) influences the growing tumour. We also discuss how dynamical changes in genetic makeup and morphological characteristics, of the tumour population, are driven by extreme changes in nutrient supply during tumour development. The simulation results indicate that aggressive phenotypes produce tumour fingering in poor nutrient, but not rich, microenvironments. The implication of these results is that an invasive outcome appears to be co-dependent upon the evolutionary dynamics of the tumour population driven by the microenvironment.

Insights into magma chamber processes from the analysis of size distribution of enclaves in lava flows: A case study from Vulcano Island (Southern Italy)

The size distribution of latitic enclaves dispersed in a rhyolitic lava flow is studied. Enclave size distribution is self-similar, a feature that can be explained by a fractal fragmentation process, and estimated fractal dimension of fragmentation is 2.50. Fragment size distribution of enclaves generated by disruption of viscous fingering structures in granitoid rocks is analyzed. It is shown that this distribution is fractal with a value of fractal dimension of fragmentation of 2.55, in close agreement with the value estimated for enclaves in the lava flow. It is suggested that the fragmentation process producing the size distribution of enclaves in the lava flow may have occurred in response to the disruption of viscous fingering morphologies generated by the injection of the more mafic magma into the felsic one. Accordingly, the size distribution of enclaves dispersed in the lava flow is considered a feature inherited from deep magma chamber processes and gives insights into magma chamber dynamics.

Sex differences in the relative lengths of metacarpals and metatarsals in gorillas and chimpanzees

Sex differences other than the simple dimorphism in size were documented for the metapodials of two primate species. Lengths of metacarpals and metatarsals were obtained from the skeletons of 64 gorillas and 42 chimpanzees. Length ratios were constructed for all possible pairings of the five bones in each individual hand and foot. For both species, several of these length ratios exhibited substantial differences between the sexes. Body size was not the basis for these sex differences; when specimens of similar size were compared, the sex differences remained. In humans, length ratios for the fingers and toes also have previously been demonstrated to exhibit sex differences, and the length ratio for the index and ring fingers (the 2D:4D ratio) has been shown to correlate with various medical conditions. Various facts suggest that length ratios in human digits are associated with androgen exposure, probably during prenatal development. For gorillas, the metacarpal length ratio showing the largest sex difference was 4Mc:5Mc in both hands, and the metatarsal length ratio showing the largest sex difference was 1Mt:2Mt in the left foot. Sex differences in length ratios also existed for chimpanzees, but they were generally smaller than for gorillas. Apparently, both gorillas and chimpanzees are affected by developmental mechanisms, possibly androgenic mechanisms, similar to those in humans. Analyses of previous measurements [Susman, R.L., 1979 Comparative and functional morphology of hominoid fingers. Am. J. Phys. Anthropol. 50, 215-236] revealed that all components of the rays are not affected equally by whatever mechanisms are responsible for the sex differences in length ratios.

Pattern formation in polymer films under the mask

This paper presents a straightforward method for patterning thin films of polymers, i.e. a prepatterned mask is used to induce self-assembly of polymers and the resulting pattern is the same as the lateral structures in the mask on a submicrometre length scale. The patterns can be formed at above T g+30 °C in a short time and the external electric field is not crucial. Electrostatic force is assumed to be the driving force for the pattern transfer. Viscous fingering and novel stress-relief lateral morphology induced under the featureless mask are also observed and the formation mechanisms are discussed.

Viscous Fingering in a Hele-Shaw Cell With Finite Viscosity Ratio and Interfacial Tension

A volume tracking method was developed to simulate time-dependent unstable viscous fingering in a Hele-Shaw cell. The effect of finite viscosity ratio μr between displacing and displaced fluids and their interfacial tension σ on finger morphology is investigated. It is shown that there exist four distinct finger patterns, depending upon the viscosity ratio, μr, and Ca′, the modified capillary number for constant flow rate, or ΔPs˙W/σ, for constant driving pressure difference. Morphology diagrams are developed to identify the ranges of the dimensionless parameters corresponding to the various finger patterns. The simulation results are validated with experiments.

Dissolution finger growth in variable aperture fractures: Role of the tip‐region flow field

We present high‐resolution computations to demonstrate the influence of the tip‐region flow field on dissolution finger morphology in variable aperture fractures. Linear fingers are observed for small values (<0.1) of the coefficient of variation of the aperture field, whereas for larger values, fingers exhibit significant branching and winding. A consequence of this behavior is that finger breakthrough times vary non‐monotonically with the coefficient of variation of the aperture field. This non‐monotonicity is a robust feature across almost all realizations for in‐plane fracture dimensions > about 25 × 25 correlation lengths.

Experimental investigation of the initial regime in fingering electrodeposition: dispersion relation and velocity measurements.

Recently a fingering morphology, resembling the hydrodynamic Saffman-Taylor instability, was identified in the quasi-two-dimensional electrodeposition of copper. We present here measurements of the dispersion relation of the growing front. The instability is accompanied by gravity-driven convection rolls at the electrodes, which are examined using particle image velocimetry. While at the anode the theory presented by Chazalviel et al. [J. Electroanal. Chem. 407, 61 (1996)] describes the convection roll, the flow field at the cathode is more complicated because of the growing deposit. In particular, the analysis of the orientation of the velocity vectors reveals some lag of the development of the convection roll compared to the finger envelope.

Assessment of digital clubbing in medical inpatients by digital photography and computerized analysis.

Digital clubbing has been associated with a large number of disorders. To overcome the limitation of subjective clinical assessment, several objective measurements have been developed among which the hyponychial angle was considered most accurate for quantification of finger clubbing. Here we investigated hyponychial angles in 123 healthy subjects and 515 medical inpatients from a tertiary hospital. Healthy subjects had a mean angle of 178.87 +/- 4.70 degrees (range: 164.78-192.10 degrees ), a finding that is well in accordance with previous results obtained using other techniques, underlining the accuracy of the chosen method of assessment. The mean angle of patients was 181.65 +/- 7.18 degrees (range: 162.22-209.19; p <0.0001 compared to healthy controls). When the upper limit of normality, i.e. 192.10 degrees, was used to define digital clubbing, the prevalence of digital clubbing in our patients was 8.9%; the percentage of clubbed fingers varied substantially among the various disease states (up to 80% in patients with cystic fibrosis). The use of digital photography with computerised analysis was found to be an easy, fast and inexpensive method for the quantification of hyponychial angles with excellent intra and inter observer reliability whilst causing no discomfort to patients. This tool may therefore be useful in further longitudinal and cross-sectional studies of finger morphology and may become an accepted standard in the diagnosis of digital clubbing.

Assessment of digital clubbing in medical inpatients by digital photography and computerized analysis.

Digital clubbing has been associated with a large number of disorders. To overcome the limitation of subjective clinical assessment, several objective measurements have been developed among which the hyponychial angle was considered most accurate for quantification of finger clubbing. Here we investigated hyponychial angles in 123 healthy subjects and 515 medical inpatients from a tertiary hospital. Healthy subjects had a mean angle of 178.87 +/- 4.70 degrees (range: 164.78-192.10 degrees ), a finding that is well in accordance with previous results obtained using other techniques, underlining the accuracy of the chosen method of assessment. The mean angle of patients was 181.65 +/- 7.18 degrees (range: 162.22-209.19; p <0.0001 compared to healthy controls). When the upper limit of normality, i.e. 192.10 degrees, was used to define digital clubbing, the prevalence of digital clubbing in our patients was 8.9%; the percentage of clubbed fingers varied substantially among the various disease states (up to 80% in patients with cystic fibrosis). The use of digital photography with computerised analysis was found to be an easy, fast and inexpensive method for the quantification of hyponychial angles with excellent intra and inter observer reliability whilst causing no discomfort to patients. This tool may therefore be useful in further longitudinal and cross-sectional studies of finger morphology and may become an accepted standard in the diagnosis of digital clubbing.

Occurrence of coexisting dendrite morphologies: immiscible fluid displacement in an anisotropic radial Hele-Shaw cell under a high flow rate regime

Viscous fingering morphologies during the displacement of a high viscosity fluid by a low viscosity immiscible fluid in a radial fourfold anisotropic Hele-Shaw cell are examined. By using the kerosene-glycerin system for which the mu/T ratio (mu being the relative viscosity and T the interfacial tension between the fluids) is about ten times higher than that for the commonly used air-glycerin system, we have been able to access the hitherto unexplored Nca greater than approximately 1 regime (capillary number Nca = U mu/T, U being the advancing fingertip velocity). Within the anisotropy-dominated regime, and when flow rates are significantly high (capillary number well beyond Nca = 1), a new phase is seen to evolve wherein the dendrites grow simultaneously along the channels and along the directions making an angle of 45 degrees with the channels, both being kinetically driven. This new phase resembles the one observed in a miscible fluid system at all flow rates of the displacing fluid. [A. G. Banpurkar et al., Phys. Rev. E 59, 2188 (1999)].

Viscous fingering of miscible fluids in an anisotropic radial Hele-Shaw cell: Coexistence of kinetic and surface-tension dendrite morphology types and an exploration of small-scale influences

The evolution of viscous fingering morphology is examined for the case of a system of miscible fluids in an anisotropic radial Hele-Shaw cell. It is shown that dendritic morphologies similar to the kinetic and surface-tension morphology types coexist for this case. The critical role of the means of introducing anisotropy in the Hele-Shaw cell is established, and an explanation of the pattern behavior is offered on the basis of shape discontinuities of the individual elements of the lattice used to induce anisotropy. The ramifications of such an explanation are experimentally verified by demonstrating a clear difference in the morphology evolution in two halves of a single Hele-Shaw cell, one half of which contains square lattice elements, and the other half of which contains circular lattice elements.

The effects of permeability heterogeneity on miscible viscous fingering: A three-dimensional magnetic resonance imaging analysis

The three-dimensional evolution of the viscous fingering instability has been visualized directly with magnetic resonance imaging (MRI). Miscible displacement of thin solute bands by aqueous solvent was investigated in packed beds of 30 μm chromatographic particles. Fingering behavior into samples of glycerol and a protein, bovine serum albumin (BSA), with viscosity ratios ranging from 1 to approximately 4, were compared. The three-dimensional morphology and dynamics of fingers were monitored to approximately millimeter spatial resolution using MRI. Linear and nonlinear fingering behavior were observed. Permeability heterogeneities with length scales on the order of the finger wavelength induced complex three-dimensional fingering patterns. Sample and column boundary effects on fingering dynamics were also noted. The differences in fingering behavior observed between albumin and glycerol samples are consistent with the wavelength predictions of linear stability analysis and the large differences in molecular diffusivity.

Comparative and functional morphology of hominoid fingers

Comparisons of hominoid metacarpals and phalanges reveal differences, many of which are closely linked to locomotor hand postures. The African apes display features of the metacarpals and phalanges which distinguish them from the other Hominoidea. These features are most evident in digits III and IV. The orangutan hand is demonstrably less well adapted to knuckle-walking and is distinctive in its adaptation to power and hook grasping of vertical and horizontal supports, respectively. Orangutan fingers possess a "double-locking" mechanism (Napier, '60), and a slight ulnad shift in the axis of the hand which results in lengthened phalanges of ray IV. Hylobatid apes are more like orangutans in their finger morphology than any of the other Hominoidea, but exhibit unique features of their own. These include elongate phalanges of fingers II-V. Human metacarpals II-V form two sets composed of II-III, and IV-V. The heads of both metacarpals II and III are characterized by axial torsion. This reflects the enhanced manipulatory role of the third finger in humans. Human distal phalanges are unique in the development of pronounced apical tufts. Multivariate analysis of metacarpal III and proximal III yields variables that array the extant apes along an arboreal-terrestrial axis, from hylobatid apes to male gorillas. The positions of taxa on this discriminant concur with observations on the locomotion of free-ranging apes.