Enhanced photoacoustic spectroscopy sensitivity through intra-cavity OPO excitation

We report an optical molecular gas sensor exhibiting high levels of selectivity and sensitivity. The outstanding sensitivity demonstrated by our technology is rooted in a novel combination of photoacoustic spectroscopy (PAS) operated within the cavity of a continuous-wave, intra-cavity Optical Parametric Oscillator (OPO). We exploit the very high circulating field present within the resonant down-converted cavity as the excitation source of the photoacoustic effect, conferring orders-of-magnitude improvement in optical excitation power. Additionally, the wide selectivity of the system arises from the inherent broad tunability and narrow optical linewidth of an OPO. Here we report the use of this technology for the detection of ammonia (NH3) as a simulant target molecule. A 3-D printed miniature PAS cell with microelectromechanical systems based (MEMS) microphone is used for the gas detection. The resonance frequency of the cell was measured at 17.9 kHz with a Q-factor of 9. The down-converted signal wave resonating within its optical cavity was tuned to 6605.6cm-1 (corresponding to a strong local NH3 absorption line) through a combination of phase matching and intra-cavity etalon control. The laser was amplitude modulated at the resonance frequency of the PAS cell, producing an average optical excitation power of ~10W in the signal arm of the OPO, to induce the photoacoustic effect for only 4W of primary diode pump power. In this work we show detection limit at the level of single parts-per-billion (ppb). Additionally, we will discuss how this technology could be readily refined to potentially demonstrate a sensitivity of tens parts-per-quadrillion

NMR relaxation study of molecular motions between unequal potential wells in solid trans, trans- muconodinitrile

Journal ArticleWe report observations of extremely unusual proton NMR relaxation rates in solid trans, transmuconodinitrile (TMD, N=C-CH = CH-CH = CH-C = N). In particular we measured, over the temperature range 77-423 °K, proton dipolar relaxation times Tw and spin lattice relaxation times Tt (at 24 and 58 MHz). The relaxation pattern is characterized by the following features: (a) very long motional r, and F 1 0 even at their respective minima, (b) no detectable motional narrowing of the line even at the Tl c minimum, (c) unequal slopes at temperatures below and above the minimum of T, (and r , 0 ) vs 1/7". and (d) significant deviations from the usual linear dependence on resonance frequency of the values of the relaxation times at their respective minima. We extended an earlier NMR theory to the case of spin lattice relaxation due to molecular reorientations between the extremely unequal potential energy wells of TMD. We were able to explain all features of the above data in terms of this theory. By comparing our data to the results of several calculations of intermolecular potential energy which used different interatomic force parameters, we were able to rule out some of these, thereby determining the best choice for the parameters in this crystal. The detailed structure of this potential profile (i.e., relative depths of the wells and energy barriers hindering rotation) was then determined from the Tt and Tw data. We thus have observed and characterized in TMD a low concentration of orientational defects which occur when a molecule occupies a higher energy well. Our observations are probably the first of such extreme NMR relaxation effects due to motions between significantly inequivalent sites

Classification for hyperspectral imaging

Hyperspectral Imaging is a method of collecting and processing the information across pre-defined electromagnetic spectrum. These measurements make it possible to derive a continuous spectrum for each pixel of the image. After necessary adjustments these image spectra can be compared with database of reflectance spectra in order to recognise tested materials. This project is conducted in cooperation between Fraunhofer Centre for Applied Photonics and Heriot-Watt Industrial Doctorate Centre in Photonics and Optics Technologies in partnership with University of Strathclyde. Fraunhofer Institute is known of world-class photonics solutions and this project aims in enhancement of one of their Hyperspectral Imaging systems with signal processing techniques. Set of classification procedures would be applied for the output of imaging spectrometer with the intention of spatial and spectral classification of objects captured by the spectrometer. Spatial classification is based on Support Vector Machine (SVM) classifier. Use of texture features of the objects is considered as a base for labelling of detected items. Spectral classification is based on Partial Least Squares (PLS) method. With database of calibration reflectance spectra, method this can be used for prediction of “end members” concentration and therefore identification of the objects captured on the hyperspectral image.

Towards a formal semantics for Ada 9X

The Ada 9X language precision team was formed during the revisions of Ada 83, with the goal of analyzing the proposed design, identifying problems, and suggesting improvements, through the use of mathematical models. This report defines a framework for formally describing Ada 9X, based on Kahn's 'natural semantics', and applies the framework to portions of the language. The proposals for exceptions and optimization freedoms are also analyzed, using a different technique

Measuring Fundamental Galactic Parameters with Stellar Tidal Streams and SIM PlanetQuest

Extended halo tidal streams from disrupting Milky Way satellites offer new opportunities for gauging fundamental Galactic parameters without challenging observations of the Galactic center. In the roughly spherical Galactic potential tidal debris from a satellite system is largely confined to a single plane containing the Galactic center, so accurate distances to stars in the tidal stream can be used to gauge the Galactic center distance, R_0, given reasonable projection of the stream orbital pole on the X_GC axis. Alternatively, a tidal stream with orbital pole near the Y_GC axis, like the Sagittarius stream, can be used to derive the speed of the Local Standard of Rest (\Theta_LSR). Modest improvements in current astrometric catalogues might allow this measurement to be made, but NASA's Space Interferometry Mission (SIM PlanetQuest) can definitively obtain both R_0 and \Theta_LSR using tidal streams.Comment: 8 pages, 4 figures, accepted for publication in ApJ Letters (minor text revisions). Version with high resolution figures available at http://www.astro.caltech.edu/~drlaw/Papers/GalaxyParameters.pd

Diferencias en las características sensoriales de los salchichones tradicionales eslovenos (suha klobasa)

Suha klobasa is a popular dry-cured sausage that is produced practically everywhere in Slovenia. The aim of this study was to investigate the main characteristics of Suha klobasa produced by different manufacturers across five different informal regions of Slovenia. Products from 31 producers, as households (11), small workshops (15) or industrial plants (3) were analysed for pH value, moisture, protein, fat, and ash, as well as for their sensory parameters, according to assessments of four profiles: appearance, texture, smell and aroma. Technological production procedures were evaluated on the basis of a survey. In average Slovenian Suha klobasa pork is used, also Suha klobasa is characterized by slow ripening and smoking or without smoking but overgrown with mould. It is always filled in a small diameter casings (32-34 mm) of the pig small intestine or permeable casings, formed in two equal-length-halves and on one side (open side) looped around, often with a wooden stick. According to the regions of Slovenia, several types of Suha klobasa can be distinguish that are defined by sausage length and surface colour, mosaic and porousness on the one hand, and acid, smoke, mould, rancid smell/aroma on the other. Suha klobasa originated from different manufacturing practices differ in visual characteristics of product (size, equality and mould), in cross-section (mosaic, porousness and glassines), and texture (hardness, toughness and integrity) but not in olfactory and aroma profile.Suha klobasa je popularna trajna kobasica koja se proizvodi gotovo svuda u Sloveniji. Cilj ovog rada bio je istražiti glavne značajke suhe klobase različitih proizvođača iz pet neslužbenih regija Slovenije. Proizvodi 31 proizvođača, odnosno domaćinstva (11), manjih gospodarstva (15) i industrijskih postrojenja (3), analizirani su na pH, vlagu, bjelančevine, masti i pepeo te senzorska svojstva, prema procjenama četiri značajke: izgled, tekstura, miris i aroma. Tehnološki proizvodni postupci ocjenjivani su na temelju ankete. Za suhu klobasu najčešće se upotrebljava svinjetina, a obilježavaju je sporo zrenje i dimljenje ili uporaba plemenitih plijesni bez dimljenja. Uvijek se puni u ovitke od svinjskog tankog crijeva ili propusne ovitke malog promjera (32-34 mm), a oblikuje se u dvije polovice jednake duljine koje su na jednoj strani (otvorena strana) presavijene, najčešće uporabom drvenog štapa. Ovisno o regiji Slovenije, možemo razlikovati nekoliko vrsta suhe klobase koje su, s jedne strane, određene duljinom kobasice i bojom površine, mozaikom i poroznošću te, s druge strane, kiselošću, dimom, plijesni i neugodnim mirisom/aromom. Iako se suhe klobase koje potječu iz različitih proizvodnih praksi razlikuju po vizualnim značajkama proizvoda (veličina, ujednačenost oblika i prisustvo plijesni), presjeku (mozaik, poroznost i sjaj) i teksturi (tvrdoća, žilavost i cjelovitost), njihovi se olfaktorni i aromatični profili ne razlikuju.Die Trockenwurst ist eine bekannte Dauerwurst, die fast überall in Slowenien hergestellt wird. In dieser Arbeit wurden die wichtigsten Eigenschaften der Trockenwurst von diversen Herstellern aus fünf nicht offiziellen Regionen Sloweniens untersucht. Die Produkte von 31 Herstellern, bzw. landwirtschaftlichen Haushalten (11), kleineren Bauernhöfen (15) und Industrieanlagen (3) wurden in Bezug auf den pHWert, die Feuchtigkeit, den Eiweiß-, Fett- und Ascheanteil sowie sensoriche Eigenschaften anhand einer Bewertung von 4 Merkmalen untersucht: Aussehen, Textur, Geruch und Aroma. Die technologischen Herstellungsverfahren wurden anhand einer Umfrage bewertet. Für die Herstellung der Trockenwurst wird am häufigsten Schweinefleisch verwendet. Das Herstellungsverfahren kennzeichnen eine langsame Reifung und Trocknung sowie der Einsatz von Edelschimmel ohne Räucherung. Sie wird immer in ein dünnes Schweinedarm oder durchlässige Därme mit einem geringen Durchmesser (32-34 mm) abgefüllt. Sie wird in zwei gleich lange Hälften geformt, die an einer Seite (der offenen Seite) gefaltet werden, meistens durch Einsatz eines Holzstocks. Abhängig von der Region Sloweniens können wir mehrere Sorten der Trockenwurst unterscheiden, die auf der einen Seite durch die Länge der Wurst und die Farbe der Oberfläche, das Mosaik und die Porosität bestimmt werden und auf der anderen Seite durch den Säuregrad, Rauch, Schimmel und unangenehmen Geruch/Aroma. Obwohl die Trockenwürste, die aus unterschiedlichen Herstellungspraxen stammen, nach ihren visuellen Eigenschaften (Größe, ausgewogene Form und Anwesenheit von Schimmel), dem Durchmesser (Mosaik, Porosität und Glanz) und der Textur (Härte, Zähigkeit und Kompaktheit) unterschieden werden, gibt es zwischen ihren olfaktorischen und aromatischen Profilen keine Unterschiede.La suha klobasa è una salsiccia secca molto popolare la cui produzione è largamente diffusa in Slovenia. La finalità di questa ricerca consiste nell’indagare le principali caratteristiche delle suhe klobase di diversi produttori provenienti da cinque regioni “ufficiose” della Slovenia. I prodotti di 31 produttori, 11 provenienti da aziende a conduzione familiare, 15 da piccoli stabilimenti e 3 da grandi impianti industriali sono stati analizzati riguardo al pH, all’umidità, alle proteine, ai grassi e alle ceneri e riguardo alle proprietà sensoriali secondo la valutazione di quattro caratteristiche: aspetto, consistenza, odore e aroma. I processi tecnologici di produzione sono stati valutati sulla base di un questionario. Per la produzione della suha klobasa prevale l’uso della carne suina. Il suo processo produttivo è caratterizzato da una lenta stagionatura e dall’affumicatura oppure dall’uso di muffe nobili senza affumicatura. Per fare la salsiccia si usa sempre il budello naturale suino (intestino tenue) o un budello sintetico permeabile di piccolo diametro (32-34 mm) che si modella in due metà d’identica lunghezza, incurvate nella parte aperta di solito con l’uso di una bastone di legno. A seconda della regione slovena di provenienza, possiamo distinguere differenti tipologie di suha klobasa, alcune caratterizzate dalla lunghezza della salsiccia e dal colore della sua superficie, dal tipico mosaico e dalla porosità, altre caratterizzate dall’acidità, dall’affumicatura, dalla muffa e dal profumo/aroma sgradevole. Sebbene le suhe klobase derivanti da differenti prassi produttive si differenzino per le peculiarità visive del prodotto (grandezza, uniformità della forma e presenza di muffe), per la sezione al taglio (mosaico, porosità e lucentezza) e per la consistenza (durezza, tigliosità e integrità), i loro profili olfattivi e aromatici non si differenziano.El salchichón es el embutido curado popular producido casi en todas partes de Eslovenia. El fin de este trabajo fue investigar las características principales del salchichón suha klobasa de diferentes productores de cinco regiones no oficiales de Eslovenia. En los productos de 31 productores, es decir de hogares (11), granjas pequeñas (15) y plantas industriales (3), fueron analizados los pH, la humedad, las proteínas, la grasa, las cenizas y las características sensoriales, según las evaluaciones de cuatro características: la apariencia, la textura, el olor y el aroma. Los procesos tecnológicos de producción fueron evaluados a base de la encuesta. Para el salchichión suha klobasa se usa más a menudo la carne de cerdo, caracterizado por la maduración y el ahumado lentos o por el uso de las moldes nobles sin el ahumado. Siempre tiene el recubrimiento de la tripa del intestino delgado porcino o los recubrimientos permeables del diámetro pequeño (32-34 mm), es formada de dos partes de longitudes similares, doblada por un lado (la parte abierta) normalmente usando un palo de madera. Dependiendo de la región de Eslovenia, es posible distinguir varios tipos de la salchicha suha klobasa, que están determinados por la longitud y el color de la superficie, el mosaico y la porosidad por un lado y por la acidez, el humo, las moldes y el olor/aroma desagradable por otro lado. Aunque las salchichas de diferentes prácticas de producción se diferencian por las características visuales del producto (el tamaño, la uniformidad de la forma y la presencia de moldes), el corte transversal (mosaico, porosidad y el brillo), y la textura (la dureza, a resistencia y la integridad), sus perfiles olfativos y aromáticos no se distinguen

Procurement Policy and Market Development for the Social Economy: Expanding the Market Opportunities for Social Enterprise, Co-operatives, and Other Social Economy Businesses

This presentation to the 2009 symposium of the BC-Alberta Social Economy Research Alliance (BALTA) reports on the results of a BALTA research project (C18) examining procurement policy and market development for the social economy.BC-Alberta Social Economy Research Alliance (BALTA) ; Social Sciences and Humanities Research Council of Canada (SSHRC

Rotorcraft noise: Status and recent developments

This paper briefly reviews rotorcraft noise mechanisms and their approximate importance for different types of rotorcraft in different flight regimes. Discrete noise is due to periodic flow disturbances and includes impulsive noise produced by phenomena which occur during a limited segment of a blade's rotation. Broadband noise results when rotors interact with random disturbances, such as turbulence, which can originate in a variety of sources. The status of analysis techniques for these mechanisms are reviewed. Also, some recent progress is presented on the understanding and analysis of tilt rotor aircraft noise due to: (1) recirculation and blockage effects of the rotor flow in hover; and (2) blade-vortex interactions in forward and descending flight