Measurement of Finger Pad Forces and Friction using Finger Nail Mounted Strain Gauges

There are currently few techniques for measuring in-vivo the forces exerted by the finger pads when handling objects and friction levels in the interface. Those that exist are intrusive and affect the manner in which an object is gripped or the interface between finger and object. A non-intrusive method would enable data to be gathered on object grip and manipulation that could improve designs to aid usability and inclusivity. The aim of this work was to assess the feasibility of determining finger pad forces and friction between a finger pad and a surface using strain gauges mounted to finger nails. The index finger and thumb were assessed as these have been shown to be used most for gripping in everyday tasks. Initially Digital Image Correlation was used to study strain across whole finger nails during a loading event to establish where it would be best to mount the strain gauges. After attachment of the strain gauges, tests were carried out normally loading finger pads against a force plate to determine strain/force relationships and the effects of slight finger side roll. Sliding tests were then also carried out in dry and lubricated conditions to see how strain varied when normal force was kept constant. Clear relationships have been established between strain and force that could be used to calibrate from measurements taken during actual object manipulation. Changing friction has also been shown to affect strain

Amorphous silica modeled with truncated and screened Coulomb interactions: A molecular dynamics simulation study

We show that finite-range alternatives to the standard long-range BKS pair potential for silica might be used in molecular dynamics simulations. We study two such models that can be efficiently simulated since no Ewald summation is required. We first consider the Wolf method, where the Coulomb interactions are truncated at a cutoff distance r_c such that the requirement of charge neutrality holds. Various static and dynamic quantities are computed and compared to results from simulations using Ewald summations. We find very good agreement for r_c ~ 10 Angstroms. For lower values of r_c, the long--range structure is affected which is accompanied by a slight acceleration of dynamic properties. In a second approach, the Coulomb interaction is replaced by an effective Yukawa interaction with two new parameters determined by a force fitting procedure. The same trend as for the Wolf method is seen. However, slightly larger cutoffs have to be used in order to obtain the same accuracy with respect to static and dynamic quantities as for the Wolf method.Comment: 10 pages; 11 fig

Perceptions and attitudes towards shoulder padding and shoulder injury in rugby union

Purpose To develop an understanding of the role of shoulder padding in rugby union by investigating player perceptions and attitudes towards shoulder padding and extending research into shoulder injuries in rugby. Methods An online survey was distributed to past and current rugby players over 13 years old in 2018. Questions related to the participants’ demographic, attitudes to shoulder padding and shoulder injury history. Results Six hundred and sixteen rugby players responded to the survey; 66.1% of respondents had worn shoulder padding at some point. The age group 24–29 years old (∆R2 = 0.03, B = − 0.53, P = 0.015) had an inverse association with padding effectiveness while playing experience groups 1–2 years (∆R2 = 0.03, B = 0.8, P = 0.032), 3–5 years (∆R2 = 0.03, B = 0.70, P = 0.002) and 6–9 years (∆R2 = 0.03, B = 0.41, P = 0) had a positive association. There are 37.1% of respondents considering shoulder padding to be effective at preventing cuts and abrasions with 21.9% finding it very effective; 50.3% considered it to be effective or very effective (9.7%) at preventing contusion; 45.5% wore padding for injury prevention, while 19.2% wore padding to protect from reoccurring injury. Sprain/ligament damage (57.5%) and bruising (55.5%) were the most commonly reported injuries. Conclusions The primary reason for wearing shoulder padding was as a means of injury prevention. Research should focus on quantifying the injury preventive capabilities of shoulder padding. Bruising, cuts and abrasion injuries to the shoulder are prevalent presenting new findings that these injuries are underreported

New fitting scheme to obtain effective potential from Car-Parrinello molecular dynamics simulations: Application to silica

A fitting scheme is proposed to obtain effective potentials from Car-Parrinello molecular dynamics (CPMD) simulations. It is used to parameterize a new pair potential for silica. MD simulations with this new potential are done to determine structural and dynamic properties and to compare these properties to those obtained from CPMD and a MD simulation using the so-called BKS potential. The new potential reproduces accurately the liquid structure generated by the CPMD trajectories, the experimental activation energies for the self-diffusion constants and the experimental density of amorphous silica. Also lattice parameters and elastic constants of alpha-quartz are well-reproduced, showing the transferability of the new potential.Comment: 6 pages, 5 figure

Speech Communication

Contains research objectives and summary of research on three research projects and reports on three research projects.National Institutes of Health (Grant 5 RO1 NS04332-12)U. S. Navy Office of Naval Research (Contract ONR N00014-67-A-0204-0069)Joint Services Electronics Program (Contract DAAB07-74-C-0630)National Institutes of Health (Grant 2 RO1 NS04332-11

Do big athletes have big hearts? Impact of extreme anthropometry upon cardiac hypertrophy in professional male athletes.

AIM: Differentiating physiological cardiac hypertrophy from pathology is challenging when the athlete presents with extreme anthropometry. While upper normal limits exist for maximal left ventricular (LV) wall thickness (14 mm) and LV internal diameter in diastole (LVIDd, 65 mm), it is unknown if these limits are applicable to athletes with a body surface area (BSA) >2.3 m(2). PURPOSE: To investigate cardiac structure in professional male athletes with a BSA>2.3 m(2), and to assess the validity of established upper normal limits for physiological cardiac hypertrophy. METHODS: 836 asymptomatic athletes without a family history of sudden death underwent ECG and echocardiographic screening. Athletes were grouped according to BSA (Group 1, BSA>2.3 m(2), n=100; Group 2, 2-2.29 m(2), n=244; Group 3, 13 mm, but in combination with an abnormal ECG suspicious of an inherited cardiac disease. CONCLUSION: Regardless of extreme anthropometry, established upper limits for physiological cardiac hypertrophy of 14 mm for maximal wall thickness and 65 mm for LVIDd are clinically appropriate for all athletes. However, the abnormal ECG is key to diagnosis and guides follow-up, particularly when cardiac dimensions are within accepted limits

Internal frequency conversion extreme ultraviolet interferometer using mutual coherence properties of two high-order-harmonic sources

International audienceWe report on an innovative two-dimensional imaging extreme ultraviolet (XUV) interferometer operating at 32 nm based on the mutual coherence of two laser high order harmonics (HOH) sources, separately generated in gas. We give the first evidence that the two mutually coherent HOH sources can be produced in two independent spatially separated gas jets, allowing for probing centimeter-sized objects. A magnification factor of 10 leads to a micron resolution associated with a subpicosecond temporal resolution. Single shot interferograms with a fringe visibility better than 30% are routinely produced. As a test of the XUV interferometer, we measure a maximum electronic density of 3×10^20 cm^−3 1.1 ns after the creation of a plasma on aluminum target

Boot-insole effects on comfort and plantar loading at the heel and fifth metatarsal during running and turning in soccer

Plantar loading may influence comfort, performance and injury risk in soccer boots. This study investigated the effect of cleat configuration and insole cushioning levels on perception of comfort and in-shoe plantar pressures at the heel and fifth metatarsal head region. Nine soccer academy players (age 15.7 ± 1.6 years; height 1.80 ± 0.40 m; body mass 71.9 ± 6.1 kg) took part in the study. Two boot models (8 and 6 cleats) and two insoles (Poron and Poron/gel) provided four footwear combinations assessed using pressure insoles during running and 180° turning. Mechanical and comfort perception tests differentiated boot and insole conditions. During biomechanical testing, the Poron insole generally provided lower peak pressures than the Poron/gel insole, particularly during the braking step of the turn. The boot model did not independently influence peak pressures at the fifth metatarsal, and had minimal influence on heel loads. Specific boot-insole combinations performed differently (P < 0.05). The 8-cleat boot and the Poron insole performed best biomechanically and perceptually, but the combined condition did not. Inclusion of kinematic data and improved control of the turning technique are recommended to strengthen future research. The mechanical, perception and biomechanical results highlight the need for a multi-faceted approach in the assessment of footwear

Bond breaking in vibrationally excited methane on transition metal catalysts

The role of vibrational excitation of a single mode in the scattering of methane is studied by wave packet simulations of oriented CH4 and CD4 molecules from a flat surface. All nine internal vibrations are included. In the translational energy range from 32 up to 128 kJ/mol we find that initial vibrational excitations enhance the transfer of translational energy towards vibrational energy and increase the accessibility of the entrance channel for dissociation. Our simulations predict that initial vibrational excitations of the asymmetrical stretch (nu_3) and especially the symmetrical stretch (nu_1) modes will give the highest enhancement of the dissociation probability of methane.Comment: 4 pages REVTeX, 2 figures (eps), to be published in Phys. Rev. B. (See also arXiv:physics.chem-ph/0003031). Journal version at http://publish.aps.org/abstract/PRB/v61/p1565