Texturing of titanium (Ti6Al4V) medical implant surfaces with MHz-repetition-rate femtosecond and picosecond Yb-doped fiber lasers

Cataloged from PDF version of article.We propose and demonstrate the use of short pulsed fiber lasers in surface texturing using MHz-repetition-rate, microjoule- and sub-microjoule-energy pulses. Texturing of titanium-based (Ti6Al4V) dental implant surfaces is achieved using femtosecond, picosecond and (for comparison) nanosecond pulses with the aim of controlling attachment of human cells onto the surface. Femtosecond and picosecond pulses yield similar results in the creation of micron-scale textures with greatly reduced or no thermal heat effects, whereas nanosecond pulses result in strong thermal effects. Various surface textures are created with excellent uniformity and repeatability on a desired portion of the surface. The effects of the surface texturing on the attachment and proliferation of cells are characterized under cell culture conditions. Our data indicate that picosecond-pulsed laser modification can be utilized effectively in low-cost laser surface engineering of medical implants, where different areas on the surface can be made cell-attachment friendly or hostile through the use of different patterns. (C) 2011 Optical Society of Americ

The muon Smasher's guide

We lay out a comprehensive physics case for a future high-energy muon collider, exploring a range of collision energies (from 1 to 100 TeV) and luminosities. We highlight the advantages of such a collider over proposed alternatives. We show how one can leverage both the point-like nature of the muons themselves as well as the cloud of electroweak radiation that surrounds the beam to blur the dichotomy between energy and precision in the search for new physics. The physics case is buttressed by a range of studies with applications to electroweak symmetry breaking, dark matter, and the naturalness of the weak scale. Furthermore, we make sharp connections with complementary experiments that are probing new physics effects using electric dipole moments, flavor violation, and gravitational waves. An extensive appendix provides cross section predictions as a function of the center-of-mass energy for many canonical simplified models

New test of modulated electron capture decay of hydrogen-like 142Pm ions: Precision measurement of purely exponential decay

An experiment addressing electron capture (EC) decay of hydrogen-like 142Pm60+ions has been conducted at the experimental storage ring (ESR) at GSI. The decay appears to be purely exponential and no modulations were observed. Decay times for about 9000 individual EC decays have been measured by applying the single-ion decay spectroscopy method. Both visually and automatically analysed data can be described by a single exponential decay with decay constants of 0.0126(7)s−1for automatic analysis and 0.0141(7)s−1for manual analysis. If a modulation superimposed on the exponential decay curve is assumed, the best fit gives a modulation amplitude of merely 0.019(15), which is compatible with zero and by 4.9 standard deviations smaller than in the original observation which had an amplitude of 0.23(4)

Husserl’s Evidence Problem

This paper examines the concept of evidence, with specific focus on the problem of evidence in Husserl's phenomenology. How this problem was dealt with and resolved by philosophers such as Plato, Descartes and Kant is compared and contrasted with Husserl's approach, and the implications of the solution offered by Husserl discussed. Finally, in light of the issues outlined, it is assessed whether or not Husserl can be said possibly to have been philosophically inclined towards notions such as idealism, empiricism, solipsism and scepticism

The Relationship Between Depression, Anxiety And Visual Reaction Times In Athletes

The aim of the study was to evaluate depression, state and trait anxiety scores and visual reaction times, and to define the impact of these variables on each other in swimmers and track and field athletes. One hundred athletes participated in this study including 25 female and 25 male national level swimmers and track and field athletes. Application of Spielberger's State-Trait Anxiety Inventory, Beck Depression Inventory (BDI) and Donder's Reaction Time Test to all participants revealed no significant relationship among obtained data except for a correlation between state and trait anxiety and depression scores (r = 0.53, r = 0.73 respectively, p < 0.001). The mean trait anxiety score in female athletes was higher than that in males (42.60 +/- 8.04. and 38.66 +/- 7.13 respectively, p < 0.05), whereas no gender differences were found for simple, choice or recognition reaction times and depression or state anxiety scores. Even though clinical depression and anxiety may affect the reaction times in patients, these results suggest that there is no correlation between anxiety and depression scores and reaction times in healthy athletes.WoSScopu