Symmetric Finger Research Articles

Symmetrical Fingertip Gangrene in a Factory Worker Exposed to Paint Thinner

Symmetrical peripheral gangrene involving the fingertips is a frequent manifestation of atherosclerotic or embolic thrombi. It may indicate an underlying systemic vasculitis or suggest an environmental exposure to freezing temperatures. We present a case of a factory worker who inadvertently got exposed to paint thinner at workplace, leading to gangrenous changes in his exposed fingertips. The clinical examination and investigations could not reveal any inflammatory or hypercoagulable state, and arterial vasospasm was found to be the most possible reason attributable to this event. The patient was managed with antiplatelet drugs and arterial vasodilators. In a case of bilateral symmetrical finger gangrene, physicians must systematically search for a professional or occupational as a putative factor.

Interfinger Synchronization Capability of Paired Fingers in Discrete Fine-Force Control Tasks.

This study examined whether within-a-hand and between-hands finger pairings would exhibit different interfinger synchronization capabilities in discrete fine-force control tasks. Participants were required to perform the designed force control tasks using finger pairings of index and middle fingers on one or two hands. Results demonstrated that the delayed reaction time and the timing difference of paired fingers showed a significant difference among finger pairings. In particular, paired fingers exhibited less delayed reaction time and timing difference in between-hands finger pairings than in within-a-hand finger pairings. Such bimanual advantage of the pairings with two symmetric fingers was evident only in the task types with relatively high amplitudes. However, for a given finger pairing, the asymmetric amplitude configuration, assigning a relatively higher amplitude to either left or right finger of paired fingers, has no significant effect on the interfinger synchronization. Therefore, paired fingers on both hands showed a bimanual advantage in the relatively high force, especially for the pairing of symmetrical fingers, whereas asymmetric amplitude configuration for a finger pairing was able to suppress the bimanual advantage. These findings would enrich the understanding of the interfinger synchronization capability of paired fingers and be referential for interactive engineering applications when leveraging the interfinger synchronization capability in discrete fine-force control tasks.

Identifying the Strength Grade for Finger Jointed Timber Species According to BS 5268-2:2002

Off-cut wood is currently considered as waste thus is dumped by saw mills as they find no means of utilising them. Sawn timber material of furniture factories and short length of sawn timbers are also considered to be wastes in the timber industry. Finger jointing technique which interlock the end joints formed by machining a number of similar tapered symmetrical fingers are recognised in this regards as effective and sustainable means of utilisation of timber wastes. The present study was undertaken to assess the strength grade of finger jointed timber based on BS 5268-2:2002. Seven timber species which are commonly used in Sri Lanka were employed for the assessment with and without finger joints. Values of Modulus of Rupture (MOR), Modulus of Elasticity (MOE), Compression parallel to grain and Compression perpendicular to grain strength of the specimens were measured. Finger jointing was performed with constant geometry (finger length 19 mm, tip width 1 mm and finger pitch 4 mm) using polyvinyl acetate (PVA, P-SWR) adhesive at normal exposure conditions. The strength properties were evaluated by Universal Testing Machine (UTM) according to BS 373:1957. Strength classes relevant to the grade stresses were not significant for finger jointed and clear specimens of Satin, Mahogany, Jack and Grandis. Both clear and finger jointed timber specimens obtained D40 for Satin and Teak, D30 for Jack, Mahogany and Grandis. Teak shows properties similar to both D35 and D40 when used as finger jointed timber. Kumbuk was shown to change from D40 to D30 while using as finger jointed timber. Finger jointed Pine showed stress grade of C22, C24 and C27.

Interfacial dynamics and pinch-off singularities for axially symmetric Darcy flow.

We study a model for the evolution of an axially symmetric bubble of inviscid fluid in a homogeneous porous medium otherwise saturated with a viscous fluid. The model is a moving boundary problem that is a higher-dimensional analog of Hele-Shaw flow. Here we are concerned with the development of pinch-off singularities characterized by a blowup of the interface curvature and the bubble subsequently breaking up into two; these singularities do not occur in the corresponding two-dimensional Hele-Shaw problem. By applying a numerical scheme based on the level set method, we show that solutions to our problem can undergo pinch-off in various geometries. A similarity analysis suggests that the minimum radius behaves as a power law in time with exponent α=1/3 just before and after pinch-off has occurred, regardless of the initial conditions; our numerical results support this prediction. Further, we apply our numerical scheme to simulate the time-dependent development and translation of axially symmetric Saffman-Taylor fingers and Taylor-Saffman bubbles in a cylindrical tube, highlighting key similarities and differences with the well-studied two-dimensional cases.

Differential contributions of the two human cerebral hemispheres to action timing.

Rhythmic actions benefit from synchronization with external events. Auditory-paced finger tapping studies indicate the two cerebral hemispheres preferentially control different rhythms. It is unclear whether left-lateralized processing of faster rhythms and right-lateralized processing of slower rhythms bases upon hemispheric timing differences that arise in the motor or sensory system or whether asymmetry results from lateralized sensorimotor interactions. We measured fMRI and MEG during symmetric finger tapping, in which fast tapping was defined as auditory-motor synchronization at 2.5 Hz. Slow tapping corresponded to tapping to every fourth auditory beat (0.625 Hz). We demonstrate that the left auditory cortex preferentially represents the relative fast rhythm in an amplitude modulation of low beta oscillations while the right auditory cortex additionally represents the internally generated slower rhythm. We show coupling of auditory-motor beta oscillations supports building a metric structure. Our findings reveal a strong contribution of sensory cortices to hemispheric specialization in action control.

Quantifying Differences among Ten Fingers in Force Control Capabilities by a Modified Meyer Model

Quantifiable differences among fingers in force control capability have both important practical and theoretical values in characterizing force control of accurate finger-tapping tasks. Following the classical Fitts’ law paradigm, we quantified the differences among ten fingers in term of speed–accuracy trade-off (SAT) in performing repetitive discrete force control tasks. Visual cues displaying targeted force magnitudes and tolerances were provided. Users were required to apply the targeted force within the given tolerance quickly and accurately by pressing a force sensor using the specified finger. We found that ten fingers obeyed the Meyer model in the SAT performance and they differed in reaction time, the index of performance (IP), and the goodness of fit for the Meyer model. A modified Meyer model was proposed to quantify the difference between ten fingers in the SAT performance using only one parameter, making the quantification easier than using the original Meyer model. Pairwise comparisons showed that the differences between symmetrical fingers on both hands were insignificant except for the pair of index fingers. These findings provided us with multiple perspectives on the differentiation among ten fingers in the force control capabilities. Our study helps lay the foundation for engineering systems that rely on finger force control ability.

A unified high-order Eulerian method for continuum simulations of fluid flow and of elastic–plastic deformations in solids

We develop a new high-order method for Eulerian simulations of solids undergoing large, elastic–plastic deformations. Thermodynamically consistent constitutive relations of classical hyperelasticity are used to describe the behavior of solids, liquids and gases in a unified manner. Two kinematic formulations, one based on the inverse deformation gradient tensor, and a second based on the symmetric Finger tensor, are used for tracking large deformations in solids. Simulations based on the Finger tensor are shown to be equivalent to those using the full inverse deformation gradient tensor at much lower computational expense. The numerical algorithm employs a 10th-order compact finite-difference scheme for spatial discretization and a 4th-order Runge–Kutta time-stepping scheme. An improved form of the Localized Artificial Diffusivity (LAD) method is used for numerical regularization of shocks and contact discontinuities. We show that this high-order numerical framework, previously used for simulations of fluid flows, is suitable for problems involving large deformations in elastic–plastic solids as well. Particular emphasis is laid on the choice of the artificial diffusivity parameters in order to sufficiently capture shocks and discontinuities in all the aforementioned continuum media with minimal added dissipation. Test cases in one and two dimensions are shown to demonstrate the feasibility and accuracy of the proposed approach. In particular, this choice of algorithms is shown to lead to excellent numerical resolution properties, and to preserve mass-consistency and curl/compatibility constraints with high order of accuracy. Potential extensions of this numerical framework include application to multi-material problems, involving compressible flow of fluids coupled to elastic–plastic deformations in solids, that are of significant engineering interest.

Towards sensitive terahertz detection via thermoelectric manipulation using graphene transistors

Graphene has been highly sought after as a potential candidate for hot-electron terahertz (THz) detection benefiting from its strong photon absorption, fast carrier relaxation, and weak electron-phonon coupling. Nevertheless, to date, graphene-based thermoelectric THz photodetection is hindered by low responsivity owing to relatively low photoelectric efficiency. In this work, we provide a straightforward strategy for enhanced THz detection based on antenna-coupled CVD graphene transistors with the introduction of symmetric paired fingers. This design enables switchable photodetection modes by controlling the interaction between the THz field and free hot carriers in the graphene-channel through different contacting configurations. Hence a novel “bias-field effect” can be activated, which leads to a drastic enhancement in THz detection ability with maximum responsivity of up to 280 V/W at 0.12 THz relative to the antenna area and a Johnson-noise limited minimum noise-equivalent power (NEP) of 100 pW/Hz0.5 at room temperature. The mechanism responsible for the enhancement in the photoelectric gain is attributed to thermophotovoltaic instead of plasma self-mixing effects. Our results offer a promising alternative route toward scalable, wafer-level production of high-performance graphene detectors.

Rigorous results in existence and selection of Saffman–Taylor fingers by kinetic undercooling

The selection of Saffman–Taylor fingers by surface tension has been extensively investigated. In this paper, we are concerned with the existence and selection of steadily translating symmetric finger solutions in a Hele–Shaw cell by small but non-zero kinetic undercooling (ε2). We rigorously conclude that for relative finger width λ near one half, symmetric finger solutions exist in the asymptotic limit of undercooling ε2 → 0 if the Stokes multiplier for a relatively simple non-linear differential equation is zero. This Stokes multiplier S depends on the parameter $\alpha \equiv \frac{2 \lambda -1}{(1-\lambda)}\epsilon^{-\frac{4}{3}}$ and earlier calculations have shown this to be zero for a discrete set of values of α. While this result is similar to that obtained previously for Saffman–Taylor fingers by surface tension, the analysis for the problem with kinetic undercooling exhibits a number of subtleties as pointed out by Chapman and King (2003, The selection of Saffman–Taylor fingers by kinetic undercooling, Journal of Engineering Mathematics, 46, 1–32). The main subtlety is the behaviour of the Stokes lines at the finger tip, where the analysis is complicated by non-analyticity of coefficients in the governing equation.

Investigate the Most Suitable Glue Type for Finger-Joints Production in Sri Lanka

Finger joint is sustainable, eco-friendly and economically valuable concept for furniture industry. It ensures the sustainable utilization of small wood cut pieces which removed as waste. Finger joints are described as interlocking end joint formed by machining a number of similar tapered symmetrical fingers in the ends of timber members using a finger joint cutter and then bonded together. Finger- jointed timber production plays a vital role in furniture industry in the world. However, issues related with the strength of the joints, fixing time, timber species and glue types etc, are still not fully investigated in Sri Lanka. This research evaluated the effects of commonly available glue types on the tensile strength of finger joint. The wood species studied were Jack, Kumbuk, Mahogany, Pine, and Teak. Mostly used Polyvinyl acetate three glue types were used for this study. The response variables measured for the tension tests. Data were gathered using Universal Testing Machine. One way ANOVA was used per each timber species to analyze the data. It was found that the highest tensile strength was recorded in SWR glue type.

Decoupling the metal layer of back contact solar cells – optical and electrical benefits

We report on our work on optimising the optical and electrical properties of back contact solar cells. We use a spin coated Novolac polymer layer between metal layer and solar cell. This helps to decouple the metal optically from the solar cell and also enables the application of symmetrical metal finger widths on solar cells with thin BSF regions and large emitter regions. While the application of the polymer layer adds process steps to the cell flow it simplifies the metal contact separation, as the metal can be laser ablated from the polymer without damaging the solar cell. Further, the polymer can be inkjet patterned and used as an etch mask for a wet chemical contact opening of the underlying dielectric passivation layer.

Reopening modes of a collapsed elasto-rigid channel

Motivated by the reopening mechanics of strongly collapsed airways, we study the steady propagation of an air finger through a collapsed oil-filled channel with a single compliant wall. In a previous study using fully compliant elastic tubes, a ‘pointed’ air finger was found to propagate at high speed and low pressure, which, if clinically accessible, offers the potential for rapid reopening of highly collapsed airways with minimal tissue damage (Heap & Juel Phys. Fluids, vol. 20 (8), 2008, 081702). The mechanism underlying the selection of that pointed finger, however, remained unexplained. In this paper, we identify the required selection mechanism by conducting an experimental study in a simpler geometry: a rigid rectangular Hele-Shaw channel with an elastic top boundary. The constitutive behaviour of this elasto-rigid channel is nonlinear and broadly similar to that of an elastic tube, but unlike the tube, the channel’s cross-section adopts self-similar shapes from the undeformed state to the point of first near wall contact. The ensuing simplification of the vessel geometry enables the systematic investigation of the reopening dynamics in terms of increasing initial collapse. We find that for low levels of initial collapse, a single centred symmetric finger propagates in the channel and its shape is set by the tip curvature. As the level of collapse increases, the channel cross-section develops a central region of near opposite wall contact, and the finger shape evolves smoothly towards a ‘flat-tipped’ finger whose geometry is set by the strong depth gradient near the channel walls. We show that the flat-tipped mode of reopening is analogous to the pointed finger observed in tubes. Its propagation is sustained by the vessel’s extreme cross-sectional profile at high collapse, while vessel compliance is necessary to stabilise it. A simple scaling argument based on the dissipated power reveals that this reopening mode is preferred at higher propagation speeds when it becomes favourable to displace the elastic channel wall rather than the viscous fluid.

Experimental study of 3D Rayleigh–Taylor convection between miscible fluids in a porous medium

The natural convection of miscible fluids in porous media has applications in several fields, such as geoscience and geoengineering, and can be employed for the geological storage of CO2. In this study, we used X-ray computer tomography to visualize 3D fingering structures associated with the Rayleigh–Taylor instability between miscible fluids in a porous medium. In the early stages of the onset of the Rayleigh–Taylor instability, a fine crinkling pattern gradually appeared at the interface. As the wavelength and amplitude increased, descending fingers formed on the interface and extended vertically downward; in addition, ascending and highly symmetric fingers formed. The adjacent fingers were cylindrical in shape and coalesced to form large fingers. The fingers appearing on the interface tended to become finer with increasing Rayleigh number, which is consistent with linear perturbation theory. When the Péclet number exceeded 10, transverse dispersion increased the finger diameter and enhanced the finger coalescence, strongly impacting the decrease in finger number density. When mechanical dispersion was negligible, the finger-extension velocity and the dimensionless mass-transfer rate scaled with the characteristic velocity and the Rayleigh number with an appropriate length scale. Mechanical dispersion not only reduced the onset time but also enhanced the mass transport.

Numerical investigation of viscous fingering in Hele-Shaw cell with spatially periodic variation of depth

Viscous fingering in a modified Hele-Shaw cell is numerically investigated. The cell allows periodic variation of depth in the lateral direction. The wavenumber n of the depth perturbation has great influence on fingering patterns. For n = 1, the fingering pattern due to the interface instability remains the same as that in the conventional Hele-Shaw cell, while the depth variation causes the steady finger to be a little narrower. For n = 2, four different fingering patterns are captured, similar to the available experimental observations in a modified Hele-Shaw cell containing a centered step-like occlusion. It is found that new fingering patterns appear as n further increases, among which, two patterns with spatial oscillation along both edges of the finger are particularly interesting. One is a symmetric oscillatory finger for n = 3, and the other is an asymmetric one for n = 4. The influence of capillary number on fingering patterns is studied for n = 3 and 4. We find that spatial oscillation of the finger nearly ceases at moderate capillary numbers and occurs again as the capillary number increases further. Meanwhile, the wide finger shifts to the narrow one. It is accompanied by a sudden decrease in the finger width which otherwise decreases continuously as the capillary number increases. The wavenumber and the amplitude of depth perturbation have little effect on the finger width.

IgM Multiple Myeloma Presenting As Hyperviscosity Syndrome with Isolated Skin Manifestation

Background:Immunoglobulin M-producing multiple myeloma (IgM MM) accounts for less than 1% of all myeloma cases. Because the disorder is rare,its clinical characteristics and long-term prognosis remain unknown. Hyperviscosity occurs from pathologic changes of either cellular or protein fractions of the blood such as are found in MM (particularly IgA and IgG3) and other diseases.Case PresentationA 65-year-old male smoker presented to emergency room (ER) with headache, dizziness, shortness of breath, symmetrical finger pain, nose bleeds, and blood in stool. On lab work hemoglobin was 7.9 gm/dl. Review of the peripheral blood smear showed atypical lymphocytes. CT chest showed left axillary and supraclavicular lymphdenopathy. Serum protein was 13 gm/dl, Serum protein electrophoresis showed a monoclonal IgM kappa gammopathy with UIEP confirming the bence jones proteinuria. A bone marrow biopsy showed about 80% cellularity with diffuse and solid neoplastic plasma cell infiltrates that were CD138+, CD20- and CD3-. Flow cytometric analysis of the bone marrow aspirate demonstrated a small fraction of clonal plasma cell population that were CD38+, CD138+, CD45-, and CD56-, Fluorescent in Situ Hybridization confirmed neoplastic plasma cells with kappa light chain restriction, and cyclinD1-. On examination, the patient had a erythematous skin changes and edematous bilateral symmetrical finger findings.Discussion:MM with IgM gammaglobulin is a rather distinct subtype of MM displaying clinical and pathologic features of both MM and WM. The clinical presentation of WM is similar to that of MM except that organomegaly is common in WM but is uncommon in MM and lytic bone disease and renal disease are uncommon in WM but are common in MM.The criteria for diagnosis of IgM myeloma (and its differentiation from WM) requires the presence of either lytic bone lesions and/or evidence of the t(11;14) translocation. It is also characterized by negative CD20, D56 and CD117 phenotype. All the reported cases of IgM myeloma had been treated with melphalan and prednisolone with suboptimal results. Some patients were treated with VAD (vincristine, adriamycin and dexamethasone) regimen, others with CTD protocol. The results were similar to the MP regimen. Radiotherapy was mainly used as palliative measure.Conclusion:Our case suggests that IgM multiple myeloma can presents as hyperviscosity syndrome with isolated skin manifestation and may have unique clinical characteristics. DisclosuresNo relevant conflicts of interest to declare.

Phase-field modeling of growth pattern selections in three-dimensional channels

In this paper, the anisotropic crystal growth in three-dimensional channels was studied using a thin-interface phase-field model. Different growth modes and dynamics behaviours, including planar front, stationary symmetrical single finger, oscillatory symmetrical single finger and multiple-finger structure, have been observed as the undercooling is increased. Lower boundary of undercooling for symmetrical single finger results from the tip-widening while the upper boundary results from the tip-splitting instability. Results show that the existence range of the symmetrical single finger depends on crystalline anisotropy, channel size and dimensionality. Moreover, an oscillatory instability, involving tip velocity and tip radius oscillations, was evidenced when the undercooling is close to but below the upper boundary. We found that the oscillatory symmetrical single finger strongly depends on the channel size and the crystalline anisotropy. Mechanism of the oscillatory mode has been discussed in details.

Motor coordination uses external spatial coordinates independent of developmental vision

The constraints that guide bimanual movement coordination are informative about the processing principles underlying movement planning in humans. For example, symmetry relative to the body midline benefits finger and hand movements independent of hand posture. This symmetry constraint has been interpreted to indicate that movement coordination is guided by a perceptual code. Although it has been assumed implicitly that the perceptual system at the heart of this constraint is vision, this relationship has not been tested. Here, congenitally blind and sighted participants made symmetrical and non-symmetrical (that is, parallel) bimanual tapping and finger oscillation movements. For both groups, symmetrical movements were executed more correctly than parallel movements, independent of anatomical constraints like finger homology and hand posture. For the blind, the reliance on external spatial factors in movement coordination stands in stark contrast to their use of an anatomical reference frame in perceptual processing. Thus, the externally coded symmetry constraint evident in bimanual coordination can develop in the absence of the visual system, suggesting that the visual system is not critical for the establishment of an external-spatial reference frame in movement coordination.

Multiple finger propagation modes in Hele-Shaw channels of variable depth

AbstractWe consider the propagation of an air finger into a wide fluid-filled channel with a spatially varying depth profile. Our aim is to understand the origin of the multiple coexisting families of both steady and oscillatory propagating fingers previously observed in experiments in axially uniform channels each containing a centred step-like occlusion. We find that a depth-averaged model can reproduce all the finger propagation modes observed experimentally. In addition, the model reveals new modes for symmetric finger propagation. The inclusion of a spatially variable channel depth in the depth-averaged equations leads to: (i) a variable mobility coefficient within the fluid domain due to variations in viscous resistance of the channel; and (ii) a variable transverse curvature term in the dynamic boundary condition that modifies the pressure jump over the air–liquid interface. We use our model to examine the roles of these two distinct effects and find that both contribute to the steady bifurcation structure, while the transverse curvature term is responsible for the distinctive oscillatory propagation modes.

Saffman–Taylor problem in filtration combustion

In the hydrodynamic approximation, postulating the combustion zone thickness to be much smaller than the channel width, the problem of filtration combustion (FC) has the same spectrum of solutions as the well-known Saffaman-Taylor (ST) problem of the displacement of a high-viscosity liquid by a low-viscosity one. In both cases, the spectrum of solutions includes families of symmetrical and asymmetrical fingers. In the ST problem, asymmetrical fingers are considered unrealizable because of the effect of surface tension at the interface between the liquids, which suppresses the formation of asymmetrical fingers. For FC, there is no exclusion of asymmetrical solutions, since the interphase boundary is a reaction front with zero surface tension. In the present work, it is experimentally demonstrated that an increase in the channel width above a critical value, a planar FC wave loses its stability and the combustion front propagates along one of the channel walls in the form of an asymmetrical finger.

Phase-field study of solidification in three-dimensional channels

Three-dimensional solidification of a pure material with isotropic properties of the solid phase is studied in cylindrical capillaries of various cross sections (circular, hexagonal, and square). As the undercooling is increased, we find, depending on the width of the capillary, a number of different growth modes and dynamical behaviors, including stationary symmetric single fingers, stationary asymmetric fingers, and oscillating double and quadruple fingers. Chaotic states are also observed, some of them in unexpected parameter regions. Our simulations suggest that the bifurcation from symmetric to asymmetric fingers is supercritical. We discuss the nature of the oscillatory states, one of which is chirality breaking, and the origin of the unexpected chaotic finger. Bifurcation diagrams are given comparing three different ratios of capillary length to channel width in the hexagonal channel as well as the three different geometries.