Excitation mapping of whispering gallery modes in silica microcavities

We report the direct observation of the electromagnetic-field distribution of whispering?gallery modes in silica microcavities (spheres and toroids). It is revealed by their excitation efficiency with a tapered fiber coupler swept along the meridian. The originality of this method lies in the use of the coupler itself for the near field mapping, eliminating the need of additional tools used in previous work. This method is successfully applied to microspheres and microtoroid

Optical nanofibers and spectroscopy

We review our recent progress in the production and characterization of tapered optical fibers with a sub-wavelength diameter waist. Such fibers exhibit a pronounced evanescent field and are therefore a useful tool for highly sensitive evanescent wave spectroscopy of adsorbates on the fiber waist or of the medium surrounding. We use a carefully designed flame pulling process that allows us to realize preset fiber diameter profiles. In order to determine the waist diameter and to verify the fiber profile, we employ scanning electron microscope measurements and a novel accurate in situ optical method based on harmonic generation. We use our fibers for linear and non-linear absorption and fluorescence spectroscopy of surface-adsorbed organic molecules and investigate their agglomeration dynamics. Furthermore, we apply our spectroscopic method to quantum dots on the surface of the fiber waist and to caesium vapor surrounding the fiber. Finally, towards dispersive measurements, we present our first results on building and testing a single-fiber bi-modal interferometer.Comment: 13 pages, 18 figures. Accepted for publication in Applied Physics B. Changes according to referee suggestions: changed title, clarification of some points in the text, added references, replacement of Figure 13

Baler -- Machine Learning Based Compression of Scientific Data

Storing and sharing increasingly large datasets is a challenge across scientific research and industry. In this paper, we document the development and applications of Baler - a Machine Learning based data compression tool for use across scientific disciplines and industry. Here, we present Baler's performance for the compression of High Energy Physics (HEP) data, as well as its application to Computational Fluid Dynamics (CFD) toy data as a proof-of-principle. We also present suggestions for cross-disciplinary guidelines to enable feasibility studies for machine learning based compression for scientific data

Antiangiogenic properties of selected ruthenium(III) complexes that are nitric oxide scavengers

The nitric oxide synthase (NOS) pathway has been clearly demonstrated to regulate angiogenesis. Increased levels of NO correlate with tumour growth and spreading in different experimental and human cancers. Drugs interfering with the NOS pathway may be useful in angiogenesis-dependent tumours. The aim of this study was to pharmacologically characterise certain ruthenium-based compounds, namely NAMI-A, KP1339, and RuEDTA, as potential NO scavengers to be used as antiangiogenic/antitumour agents. NAMI-A, KP1339 and RuEDTA were able to bind tightly and inactivate free NO in solution. Formation of ruthenium-NO adducts was documented by electronic absorption, FT-IR spectroscopy and (1)H-NMR. Pretreatment of rabbit aorta rings with NAMI-A, KP1339 or RuEDTA reduced endothelium-dependent vasorelaxation elicited by acetylcholine. This effect was reversed by 8-Br-cGMP. The key steps of angiogenesis, endothelial cell proliferation and migration stimulated by vascular endothelial growth factor (VEGF) or NO donor drugs, were blocked by NAMI-A, KP1339 and RuEDTA, these compounds being devoid of any cytotoxic activity. When tested in vivo, NAMI-A inhibited angiogenesis induced by VEGF. It is likely that the antitumour properties previously observed for ruthenium-based NO scavengers, such as NAMI-A, are related to their NO-related antiangiogenic propertie

The -786T>C promoter polymorphism of the NOS3 gene is associated with prostate cancer progression

<p>Abstract</p> <p>Background</p> <p>There is no biological or epidemiological data on the association between <it>NOS3 </it>promoter polymorphisms and prostate cancer. The polymorphisms in the promoter region of <it>NOS3 </it>gene may be responsible for variations in the plasma NO, which may promote cancer progression by providing a selective growth advantage to tumor cells by angiogenic stimulus and by direct DNA damage.</p> <p>Methods</p> <p>This study aimed evaluating the <it>NOS3 </it>promoter polymorphisms by PCR-SSCP and sequencing, associating genotypes and haplotypes with <it>NOS3 </it>expression levels through semi-quantitative RT-PCR, and with <it>PCA</it>3 mRNA detection, a specific tumor biomarker, in the peripheral blood of pre-surgical samples from 177 patients; 83 PCa and 94 BPH.</p> <p>Results</p> <p>Three novel SNPs were identified -764A>G, -714G>T and -649G>A in the <it>NOS3 </it>gene promoter region, which together with the -786T>C generated four haplotypes (N, T, C, A). <it>NOS3 </it>gene expression levels were affected by the -786T>C polymorphism, and there was a 2-fold increase in <it>NOS3 </it>levels favored by the incorporation of each C allele. <it>NOS3 </it>levels higher than 80% of the constitutive gene expression level (<it>B2M</it>) presented a 4-fold increase in PCa occurrence.</p> <p>Conclusion</p> <p>The -786T>C polymorphism was the most important promoter alteration of the <it>NOS3 </it>gene that may affect the PCa progression, but not its occurrence, and the incorporation of the C allele is associated with increased levels of <it>NOS3 </it>transcripts. The <it>NOS3 </it>transcript levels presented a bimodal behavior in tumor development and may be used as a biomarker together with the <it>PCA3 </it>marker for molecular staging of the prostate cancer.</p

Neodymium photoluminescence in Whispering Gallery Modes of toroidal microcavities

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Neodymium photoluminescence in Whispering Gallery Modes of toroidal microcavities

We report on light emission from high-Q neodymium-implanted silica microtoroids. After description of the fabrication process of microtoroids, Neodymium light emission is analysed. This emission is coupled to various modes of the cavity. Using evanescent wave detection, we achieve selective detection of Whispering Gallery Modes of a microtoroid