Single-detector polarization-sensitive optical frequency domain imaging using high-speed intra A-line polarization modulation

We demonstrate a novel high-speed polarization-sensitive optical frequency domain imaging system employing high-speed polarization modulation. Rapid and continuous polarization modulation of light prior to illumination of the sample is accomplished by shifting the frequency of one polarization eigenstate by an amount equal to one quarter of the digitization sampling frequency. This approach enables polarization-sensitive imaging with a single detection channel and overcomes artifacts that may arise from temporal variations of the birefringence in fiber-optic imaging probes and spatial variation of birefringence in the sample.     

Laser Chemical Processing (LCP)—A versatile tool for microstructuring applications

Laser Chemical Processing (LCP) is presented as a novel microstructuring method for multiple applications. Via the combination of a chemical liquid jet and a laser beam, thermochemical and photochemical reactions can be initiated. Due to the free choice of the chemistry for the carrier liquid and the laser source, efficient processes can be devised for a large variety of applications. We present some examples for the microstructuring of silicon with the focus on etching, selective doping of phosphorous and the combination of etching and doping.     

Deposition and stoichiometry control of Nd-doped gadolinium gallium garnet thin films by combinatorial pulsed laser deposition using two targets of Nd:Gd<Subscript>3</Subscript>Ga<Subscript>5</Subscript>O<Subscript>12</Subscript> and Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>

We have demonstrated pulsed laser deposition of Nd-doped gadolinium gallium garnet on Y₃Al₅O₁₂ by the simultaneous ablation of two separate targets of Nd:Gd₃Ga₅O₁₂ (GGG) and Ga₂O₃. Such an approach is of interest as a method of achieving stoichiometry control over films whilst the growth parameters are kept constant and optimal for high quality crystal growth. We show here how the stoichiometry and resultant lattice parameter of a film can be controlled by changing the relative deposition rates from the two targets. Films have been grown with enough extra Ga to compensate for the deficiency that commonly occurs when depositing only from a GGG target. We have also grown crystalline GGG films with an enriched Ga concentration, and this unconventional approach to film stoichiometry control may have potential applications in the fabrication of films with advanced compositionally graded structures.     

On the choice of the regularization parameter for the interpretation of ARXPS data using a multilayer model

We report our investigation of the dependence of the profile extracted from ARXPS data on the value of the regularization parameter α. We argue that a choice based upon the L-curve criterion, which does not require knowledge of the variances in the data, is less satisfactory than an approach based on choosing α such that χ²/N = 1.     

First-Passage and Extreme-Value Statistics of a Particle Subject to a Constant Force Plus a Random Force

We consider a particle which moves on the x axis and is subject to a constant force, such as gravity, plus a random force in the form of Gaussian white noise. We analyze the statistics of first arrival at point x ₁ of a particle which starts at x ₀ with velocity v ₀. The probability that the particle has not yet arrived at x ₁ after a time t, the mean time of first arrival, and the velocity distribution at first arrival are all considered. We also study the statistics of the first return of the particle to its starting point. Finally, we point out that the extreme-value statistics of the particle and the first-passage statistics are closely related, and we derive the distribution of the maximum displacement m=max  _t [x(t)].     

Kinetic Carbon Isotope Effects in the Decarbonylation of Lactic Acid of Natural Isotopic Composition and of [1-14C] Lactic Acid

Studies of carbon-13 and carbon-14 kinetic isotope effects (K. I. E.) in the decarbonylation of lactic acid (L. A.) in sulphuric acid and in phosphoric acids media have been summarized and compared with earlier studies of ¹⁴C and ¹³C K. I. E. in the decarbonylation of formic and oxalic acids in concentrated sulphuric acid. Supplementary data concerning the decarbonylation of L. A. in sulphuric acid diluted with water and in pyrophosphoric acid are presented and discussed. The observed temperature dependences of ¹³C and ¹⁴C K. I. E. in concentrated H₂SO₄ and in concentrated phosphoric acids media have been rationalized by invoking a change of the mechanism of decarbonylation of L. A. in concentrated sulphuric and phosphoric acids with temperature. Preliminary calculational results concerning ¹³C and ^1??C K. I. E. in decarbonylation processes are also presented. In H₂SO₄ diluted with water and in H₃PO₄ diluted with water the temperature dependence of ¹³C and ¹⁴C K. I. E. is normal and well reproduced by one frequency approximation. In concentrated sulphuric acid and in concentrated phosphoric acids besides the C—OH bond rupture the rupture of a C—C bond had to be considered also to reproduce the observed ¹³C K. I. E. in selected temperature regions.     

Infrared evidence for the folded-chain model of trans-1,4-polybutadiene

The influence of the first-order crystalline transformation at about 60°C on the infrared bands of trans-1,4-polybutadiene yields microscopic information that supports the two-component microcrystalline model of a folded chain having loose and tight end loops at the lamellar surfaces. The temperature dependence of the band parameters of the 908-cm^?1 vinyl band indicates that 1,2-(side vinyl) units are not easily taken into the crystalline component, thus forming long loops at the crystal surface that account for the micro-Brownian motion detected in the low-temperature phase. The results argue that infrared band parameters are excellent probes for details of the thermodynamics and morphology of polymers.     

Effects of the Synergy of Hardness and Resilience on the Akron Abrasion Properties of SBR Vulcanizates

The hardness (H) and resilience (R) of rubber vulcanizates were combined together in this paper, named as hardness–resilience product (H⁴R), and its relationship with the Akron abrasion loss was investigated using various styrene-butadiene rubber (SBR) vulcanizates possessing specific hardness and resilience characteristics as samples. For the unfilled SBR vulcanizates with different chain microstructure, possessing high elastic resilience and low hardness, the results showed that their Akron abrasion loss had a good linear relationship with the log(H⁴100R). This linear relationship also occurred when these SBRs were filled with 50 phr carbon black. For two particular types of SBR, after being filled with different fractions of carbon black and aged for different times, all their Akron abrasion losses (including unaged, aged for 24 h, and aged for 48 h) also had a good linear relationship with the log(H⁴100R). However, this linear relationship weakened for one of the SBRs after being aged for 48 h. In the high H⁴R region (the carbon black fractions being 60 and 70 phr), the data obviously deviated from the fitting curve due to the high hardness of the aged vulcanizates. However, after being filled with 50 phr of various kinds of carbon blacks, the relationships between abrasion loss and log(H⁴100R) were also approximately linear, with the correlation coefficient of the fitting curves being 0.99966 and 0.99878, respectively, for the two types of SBR.     

From the Anderson Model on a Strip to the DMPK Equation and Random Matrix Theory

We study weakly disordered quantum wires whose width is large compared to the Fermi wavelength. It is conjectured that such wires display universal metallic behavior as long as their length is shorter than the localization length (which increases with the width). The random matrix theory that accounts for this behavior—the DMPK theory—rests on assumptions that are in general not satisfied by realistic microscopic models. Starting from the Anderson model on a strip, we show that a twofold scaling limit nevertheless allows to recover rigorously the fundaments of DMPK theory, thus opening a way to settle some conjectures on universal metallic behavior.     

Effects of mobile phone exposure on time frequency fine structure of transiently evoked otoacoustic emissions

Mobile phones have become very commonly used worldwide within a short period of time. To date there is only limited knowledge about interaction between electromagnetic fields (EMFs) emitted by mobile phones and the auditory function. Moreover, there is widespread concern that there may be potential for harm. The aim of this study was to assess potential subtle changes in cochlear function by measuring the temporal and spectral fine structure of transiently evoked otoacoustic emissions (TEOAE) in normal hearing subjects after exposure to EMFs emitted by Global System for Mobile Communication (GSM) mobile phones. TEOAEs were recorded in 27 healthy young adults before and after 10 min of real or sham exposure in a double-blind design. TEOAE data were analyzed both globally (broadband analysis) and using the Wavelet Transform (analysis of the time-frequency fine structure). The broadband analysis revealed no significant effect on TEOAEs related to exposure, confirming results of previous studies; in addition, no significant change was detected in the analysis of the elementary wavelet components, suggesting that the temporal and spectral fine structure of TEOAEs is not affected by 10 min exposure to low-intensity EMFs emitted by GSM mobile phones.