198,684 research outputs found
Mary Hodgkinson
No full textMary Armina (Mina) Haws Hodgkinson is the wife of Louis M. Hodgkinson. She was born June 21, 1887 and died September 25, 1965
Lowell Hodgkinson
No full textLowell Hodgkinson is pictured his junior year at Uintah High School. He is the son of Louis M. and Mary Hodgkinson
Mary Armina Hodgkinson
No full textMary Armina (Mina) Haws Hodgkinson is the wife of Louis M. Hodgkinson. She was born June 21, 1887 and died September 25, 1965
Comparison of self-referencing techniques for photothermal detection of trace compounds in water
No full textSelf-referencing techniques are compared for a closed-cell photothermal detector that uses a water meniscus as a pressure sensor. Deflection of the meniscus was measured using an optical fibre Fabry–Perot interferometer. For long measurement integration times, interference fringe drift was a serious limitation on the detection repeatability for non self-referenced measurements. Two self-referencing techniques were compared for measurements of optical absorption. The first technique used a simultaneous reference absorption signal at a second wavelength, and the second used a simultaneous volumetric modulation within the cell. Both methods have been evaluated with photothermal excitation by a 658-nm LED, a 478-nm LED and a UV discharge lamp. For the detection of absorption in aqueous solutions, the two methods had similar performance. However, the volumetric method could be used for detection of any absorbing compound, regardless of its absorption spectrum and was more convenient to use
Performance of a photothermal detector with turbid liquids
No full textA closed-cell photothermal detector for aqueous analytes has been evaluated at 254nm and 678nm. The
detector used a water meniscus as a pressure sensor, whose periodic deflection was measured using a low
finesse optical fibre Fabry-Perot interferometer. Performance was compared with a commercial diode-array
spectrometer and found to be similar for absorption measurements in non-turbid samples, but the results
were affected up to 60 times less by scattered light. Finally the photothermal cell was converted into an
integrating cavity using ceramic inserts, showing freedom from scattering related errors at 678nm but a
degradation in performance at 254nm
Chapter 04. Framework to understand postgraduate students' adaption of academics' teaching materials as OER
No full textThis chapter addresses a way of responding to one of the key challenges of OER contribution, namely academics' lack of time to re-purpose teaching materials originally intended for campus-based face-to-face lectures as stand-alone Open Educational Resources (OER). It describes how masters' students, tutors and interns at the University of Cape Town have been engaged to support the innovative practice of adapting academics' existing teaching materials into OER
Alien Registration- Hodgkinson, Freda M. (South Berwick, York County)
No full texthttps://digitalmaine.com/alien_docs/6393/thumbnail.jp
Photothermal detection of trace optical absorption in water by use of visible-light-emitting diodes
No full textVisible light emitting diodes of three different colors have been used to detect an absorbing compound
(potassiumpermanganate) in trace quantities in aqueous solution. Photothermal absorption in a closed cell
caused deflection of a water meniscus held at a small pinhole. The displacement was monitored using
optical fiber interferometry. The technique was limited by LED emission intensities and environmental
acoustic noise, giving minimum detectable absorption coefficients of 2x10-4 cm-1 at 478 nm and 658 nm,
and 3x10-4 cm-1 at 524 nm. The magnitude and form of meniscus deflection signals were shown to be in
good agreement with theory
Photoacoustic and photothermal detection of trace compounds in water
No full textThe detection of trace compounds in water using photoacoustic or photothermal techniques is presented, with specific reference to on-line water quality monitoring. A key requirement was the use of simple, robust and inexpensive light sources, whose continuous-wave output was modulated electronically at relatively low frequencies (~100Hz). Two closed-cell, low-frequency optical absorption detectors have been developed and evaluated. In both cases, a novel theoretical treatment revealed that the optimum cell design had a pressure sensor whose mechanical compliance was equal to the bulk compliance of the enclosed water. High sensitivity was achieved despite the use of lower power light sources, potentially extending the applicability of photothermal/photoacoustic methods to low-cost systems.The photoacoustic cell incorporated a thin-walled piezoelectric cylinder. Using a 678nm laser diode emitting 1.4±0.2 mW rms, a minimum detectable absorption coefficient of 3x10-3cm-1 was demonstrated.Better performance was achieved using the photothermal detector. Photothermal expansion in aqueous samples caused the deflection of a water meniscus held across a 200 μm-radius pinhole. Meniscus displacement was monitored using fibre optic interferometry. The magnitude and form of photothermal meniscus deflection signals were shown to be in good agreement with theory. Absorption by 1.5ppb anthracene in water was detected using a mercury discharge lamp (254nm) as an excitation source, and light emitting diodes were used to excite photothermal signals in a liquid (water) for the first time. The technique was limited by light source emission intensities and environmental acoustic noise, for example giving a minimum detectable absorption coefficient of 2x10-4cm-1 using an LED emitting 0.38±0.06 mW rms.The minimum detectable absorption coefficients of the photothermal detector and of a conventional transmission spectrometer were found to be similar, but the photothermal technique was far less sensitive to the effects of light scattering. The ability to detect trace contaminants in water, in the presence of turbidity, is of great importance to the water industry.</p
Effect of incisor retraction on facial aesthetics
No full textIncisor retraction may result in lip retraction, interlabial gap closure and increase of the nasolabial angle but a clear consensus on the effect of incisor retraction on facial aesthetics has not yet been achieved. Despite current evidence being weak, it seems to indicate that in a well-managed orthodontic case, with or without extractions, the soft-tissue and facial aesthetic changes are generally favourable or clinically insignificant
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