Slow light in paraffin-coated Rb vapor cells

We present preliminary results from an experimental study of slow light in anti-relaxation-coated Rb vapor cells, and describe the construction and testing of such cells. The slow ground state decoherence rate allowed by coated cell walls leads to a dual-structured electromagnetically induced transparency (EIT) spectrum with a very narrow (<100 Hz) transparency peak on top of a broad pedestal. Such dual-structure EIT permits optical probe pulses to propagate with greatly reduced group velocity on two time scales. We discuss ongoing efforts to optimize the pulse delay in such coated cell systems.Comment: 6 pages, 6 figures, submitted to Journal of Modern Optic

Mathematical Modelling of Optical Coherence Tomography

In this chapter a general mathematical model of Optical Coherence Tomography (OCT) is presented on the basis of the electromagnetic theory. OCT produces high resolution images of the inner structure of biological tissues. Images are obtained by measuring the time delay and the intensity of the backscattered light from the sample considering also the coherence properties of light. The scattering problem is considered for a weakly scattering medium located far enough from the detector. The inverse problem is to reconstruct the susceptibility of the medium given the measurements for different positions of the mirror. Different approaches are addressed depending on the different assumptions made about the optical properties of the sample. This procedure is applied to a full field OCT system and an extension to standard (time and frequency domain) OCT is briefly presented.Comment: 28 pages, 5 figures, book chapte

Violation of the London Law and Onsager-Feynman quantization in multicomponent superconductors

Non-classical response to rotation is a hallmark of quantum ordered states such as superconductors and superfluids. The rotational responses of all currently known single-component "super" states of matter (superconductors, superfluids and supersolids) are largely described by two fundamental principles and fall into two categories according to whether the systems are composed of charged or neutral particles: the London law relating the angular velocity to a subsequently established magnetic field and the Onsager-Feynman quantization of superfluid velocity. These laws are theoretically shown to be violated in a two-component superconductor such as the projected liquid metallic states of hydrogen and deuterium at high pressures. The rotational responses of liquid metallic hydrogen or deuterium identify them as a new class of dissipationless states; they also directly point to a particular experimental route for verification of their existence.Comment: Nature Physics in print. This is an early version of the paper. The final version will be posted 6 months after its publication Nature Physics, according to the journal polic

The Association between Vitamin D Receptor Expression and Prolonged Overall Survival in Breast Cancer.

Summary In this study, we analyzed vitamin D receptor (VDR) expression and survival in a breast cancer patient cohort of 82 breast cancer patients. Immunohistochemical analysis was possible in 91.5% of the patients (75/82). Staining was evaluated using the semi-quantitative assay according to Remmele and Stegner (immunoreactivity score [IRS]). IRS 0–1 was negative/very low, IRS 2–4 was moderate to high, and IRS 6–12 was high. Statistical analysis was performed by Spearman’s correlation test (p<0.05 significant). Overall survival was analyzed using Kaplan-Meier estimations. Only 6 patients had a negative IRS. Moderate IRS values were present in 20 patients. Most of the patients had a high IRS (49). For survival analysis, data were dichotomized (IRS 0–4: negative to moderate and IRS 6–12: high VDR expression). In univariate analysis, VDR expression showed significant differences in progression-free survival (PFS) and overall survival (OS). Patients with high IRS scores showed significantly better PFS and OS than patients with moderate/negative IRS scores for VDR expression. Tumor size was significantly correlated to PFS. When analyzed separately, the three different IRS groups showed significant differences in VDR expression. The present data suggest that VDR expression in breast cancer tissue may be of clinical significance, and the results provide evidence that VDR may be a factor with prognostic relevance. (J Histochem Cytochem 60:121–129, 2012). Keywords: breast cancer, vitamin D receptor, immunohistochemistry, prognosi

Baseline and triangulation geometry in a standard plenoptic camera

In this paper, we demonstrate light field triangulation to determine depth distances and baselines in a plenoptic camera. The advancement of micro lenses and image sensors enabled plenoptic cameras to capture a scene from different viewpoints with sufficient spatial resolution. While object distances can be inferred from disparities in a stereo viewpoint pair using triangulation, this concept remains ambiguous when applied in case of plenoptic cameras. We present a geometrical light field model allowing the triangulation to be applied to a plenoptic camera in order to predict object distances or to specify baselines as desired. It is shown that distance estimates from our novel method match those of real objects placed in front of the camera. Additional benchmark tests with an optical design software further validate the model’s accuracy with deviations of less than 0:33 % for several main lens types and focus settings. A variety of applications in the automotive and robotics field can benefit from this estimation model

Uncovering Bugs in Distributed Storage Systems during Testing (not in Production!)

Testing distributed systems is challenging due to multiple sources of nondeterminism. Conventional testing techniques, such as unit, integration and stress testing, are ineffective in preventing serious but subtle bugs from reaching production. Formal techniques, such as TLA+, can only verify high-level specifications of systems at the level of logic-based models, and fall short of checking the actual executable code. In this paper, we present a new methodology for testing distributed systems. Our approach applies advanced systematic testing techniques to thoroughly check that the executable code adheres to its high-level specifications, which significantly improves coverage of important system behaviors. Our methodology has been applied to three distributed storage systems in the Microsoft Azure cloud computing platform. In the process, numerous bugs were identified, reproduced, confirmed and fixed. These bugs required a subtle combination of concurrency and failures, making them extremely difficult to find with conventional testing techniques. An important advantage of our approach is that a bug is uncovered in a small setting and witnessed by a full system trace, which dramatically increases the productivity of debugging

The parabola theorem on continued fractions

Using geometric methods borrowed from the theory of Kleinian groups, we interpret the parabola theorem on continued fractions in terms of sequences of Möbius transformations. This geometric approach allows us to relate the Stern–Stolz series, which features in the parabola theorem, to the dynamics of certain sequences of Möbius transformations acting on three-dimensional hyperbolic space. We also obtain a version of the parabola theorem in several dimensions

Prevalence of liver fluke on the West Coast

A study of all herds (n=430) supplying Westland Milk Co-op were tested with an IDEXX Bulk Milk Elisa (BME) (IDEXX Fasciolosis Verification, IDEXX Europe BV, Hoofdorp, The Netherlands) which characterises herds into intensities of infection (Nil, Low, Medium, Strong). These equate to liver fluke infection prevalence of 0%, 50% within the sampled herd. Overall, the distribution of herds as analysed in the autumn of 2017 was Nil=31%, Low=11%, Medium=14%, Strong=43%. It was notable that some regions had much higher levels of infection than others.fals

Effect of water immersion on monomer and strength of FRC

This journal suppl. entitled: Abstracts of the Academy of Dental Materials Annual Meeting, 8-11 October 2014 - Bologna, ItalyPURPOSE: There is an interest in the use of fiber-reinforced composite (FRC) to support the concept of minimal invasive dentistry. The exposure of FRC to the oral environment causes detrimental effect of water sorption (Takashi et al. Dent Mat 2006 22:291). With time water molecules will act as plasticizers and decrease the mechanical properties (Mese and Guzel. J Prosthet Dent 2008 99:153). Monomer system is the backbone of the dental composite (Garcia et al. Clinical Dentistry 2005: 215) and residual monomer may dissolve in water (Tanaka et al. J Oral Rehab 1991 18:353). Some released monomers are knownto elicit cytotoxic effects (Sakaguchi and Powers. Craig’s Restorative Dental Materials 2012:343), and methyl methacrylate (MMA) is mentioned as cytotoxic (Pradeep and Sreekumar. J Contemp Dent Pract 2012 6:838). This study investigated the effect of water immersion duration on monomer release and the compressive strength of fiber-reinforced composite. METHODS AND MATERIALS: Materials used were: E-glass fibre (Stick Tech, Finland), bis-GMA (Sigma–Aldrich, USA), MMA (ProSciTech, Australia), CQ (Esstech, USA) and CEMA (Esstech, USA). Fifteen specimens (2mm×2mm×25mm) with the composition of: 78.4% bis-GMA+19.6%MMA+ 1.0%CQ + 1.0%CEMA were prepared and divided into 2 groups: compressive strength (CS-12specimens) and residual monomer (RM-3specimens). Each specimen had two fiber rovings of 25mm and placed in a mould, and light-cured with halogen light-curing unit on both sides for 3×40 s. Specimens from each group were divided into three groups based on the water immersion durations (1, 14 and 21 days) and immersed into 10 ml distilled water at 37 ◦C. The three RM-specimens were analyzed using HPLC to test the residual monomer concentration. All CS-specimens were tested using UTM (Torsee’s UTM, Tokyo Testing Machine Mfg., Co., Ltd., Japan) for the compressive strength. RESULTS: The data of MMA concentration was descriptively analyzed. It started on day 1 (2352.96µg/ml) followed by an increase on day14 (3567.15µg/ml) and decreased on day 21 (2427.19µg/ml). Compressive strength showed an average (MPa) for day 1 (93.84±8.30); day 14 (67.83±4.82) and day 21 (51.08±2.10), respectively. Data from the compressive strength was analyzed by ANOVA, and it proved a significant decrease as the water immersion duration increases (p < 0.05). CONCLUSION: The duration of water immersion of e-glass FRC showed different effect on the concentration of released monomer and the compressive strength. Highest concentration of MMA concentration occurred on day 14 and followed by a decrease. As for the compressive strength, it decreased as the water immersion duration increased.postprin