Light Fluence Rate and Tissue Oxygenation (StO2) Distributions Within the Thoracic Cavity of Patients Receiving Intraoperative Photodynamic Therapy for Malignant Pleural Mesothelioma

The distributions of light and tissue oxygenation (S_tO₂) within the chest cavity were determined for 15 subjects undergoing macroscopic complete resection followed by intraoperative photodynamic therapy (PDT) as part of a clinical trial for the treatment of malignant pleural mesothelioma (MPM). Over the course of light delivery, detectors at each of eight different sites recorded exposure to variable fluence rate. Nevertheless, the treatment-averaged fluence rate was similar among sites, ranging from a median of 40–61 mW cm⁻² during periods of light exposure to a detector. S_tO₂ at each tissue site varied by subject, but posterior mediastinum and posterior sulcus were the most consistently well oxygenated (median S_tO₂ >90%; interquartile ranges ~85–95%). PDT effect on S_tO₂ was characterized as the S_tO₂ ratio (post-PDT S_tO₂/pre-PDT S_tO₂). High S_tO₂ pre-PDT was significantly associated with oxygen depletion (S_tO₂ ratio < 1), although the extent of oxygen depletion was mild (median S_tO₂ ratio of 0.8). Overall, PDT of the thoracic cavity resulted in moderate treatment-averaged fluence rate that was consistent among treated tissue sites, despite instantaneous exposure to high fluence rate. Mild oxygen depletion after PDT was experienced at tissue sites with high pre-PDT S_tO₂, which may suggest the presence of a treatment effect.     

A versatile surface rheometer

Summary In the study of the physical properties of hydrocolloid films at the aqueous-air interface and aqueousoil interface it is necessary to be able to look at the whole range of rheological properties from low viscosity liquid to viscoelastic solid. It is desirable to follow all these stages, in succession, sometimes, with one piece of apparatus.The apparatus developed can be used in three basic modes without modification. Continuous shear (as a surface Couette viscometer). Free Oscillation, and Creep and Creep Recovery.In continuous shear, a cylindrical dish containing the aqueous solution of the hydrocolloid and the oil layer, is rotated about its vertical axis at a known constant velocity. The shear stress is determined from the angular deflection of a shallow angled biconical pendulum suspended in the oil-water interface by means of a long vertical wire. The shear rate is calculated from the speed of rotation of the dish.In free oscillation the amplitude and period of oscillation of the biconical pendulum, suspended on the wire are recorded using an optical lever, photo-cell, and pulse counting circuit. or observed directly from the movement of a spot of light projected onto a horizontal scale.In creep, constant surface shear stress is applied, by arranging that the twist in the vertical wire supporting the biconical. pendulum, remains constant during the experiment. A servomechanism, controlled by the optical lever and photo-cell, mentioned above, drives the cylindrical dish by an amount necessary to maintain the constant shear stress. The deformation of the interfacial film is recorded in digital form as the number of pulses fed to a stepping motor which, itself, is an integral part of the servomechanism.The smallest deformation of the interfacial film corresponds to an angular movement of the pendulum bob of about 3 × 10^–4 radian. The applied torque depends on the thickness of the suspension wire and the twist in it. The latter can be measured to 0.25°.

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Zusammenfassung Bei Untersuchungen der physikalischen Eigenschaften hydrokolloidaler Filme an den Grenzflächen von einem wäßrigen Medium und Luft sowie wäßrigem Medium und Öl sollte man unbedingt den gesamten Bereich der Theologischen Eigenschaften in Betracht ziehen, d. h. von Flüssigkeiten mit geringer Viskosität bis zu viskoelastischen Feststoffen. Es ist wünschenswert, alle diese aufeinanderfolgenden Stufen mit einem Gerät zu untersuchen.Das Gerät, das entwickelt wurde, kann ohne Modifikation auf drei verschiedene Arten gebraucht werden: Kontinuierliche Scherversuche (als Oberflächen-Couette-Viskosimeter), freie Schwingungen und Kriech- sowie Kriecherholungsversuche.Bei kontinuierlich-veränderlicher Schubspannung wird eine zylinderförmige Schale mit der wäßrigen Lösung des Hydrokolloids und der Ölschicht mit einer bekannten konstanten Geschwindigkeit um die senkrechte Achse gedreht. Vom Ausschlagwinkel eines zweiseitig konisch zulaufenden Pendels, das mit einem langen Draht in der Öl-Wassergrenzschicht hängt, wird die Schubspannung bestimmt. Die Schergeschwindigkeit folgt aus der Umlaufgeschwindigkeit der Schale.Bei der freien Schwingung werden die Amplitude und die Periode des bikonischen Pendels durch ein optisches System mit Photozelle und Impulszähleinheit oder direkt durch die Bewegung eines Lichtstrahles, der auf eine horizontale Skala projiziert wird, bestimmt.Beim Kriech-Versuch wird eine konstante Oberflächen-Schubspannung erzeugt, indem die Verdrehung des vertikalen Drahtes, an dem das bikonische Pendel aufgehängt ist, während des Experimentes konstant gehalten wird. Ein mit Lichtstrahl und Photozelle kontrollierter Servomechanismus dreht die zylinderförmige Schale immer so, daß die Schubspannung gleichbleibt. Die Deformation des Grenzflächenfilmes wird als Anzahl von Impulsen numerisch gespeichert, die dem Schrittmotor des Servomechanismus zugegangen sind.Die geringste Deformation des Grenzflächenfilmes entspricht einer Winkelbewegung des Pendelkörpers von etwa 3·10^–4 im Bogenmaß. Das übertragene Moment ist unabhängig von der Stärke und der Verdrehung des Aufhängedrahtes. Die geringste Verdrehung, die gemessen werden kann, beträgt 0.25°.

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Paper presented to the British Society of Rheology Conference on Rheology in Medicine and Pharmacy, London, April 14–15, 1970.     

A combinatorial approach to the discovery of biocidal six-residue cyclic D,L-alpha-peptides against the bacteria methicillin-resistant Staphylococcus aureus (MRSA) and E. coli and the biofouling algae Ulva linza and Navicula perminuta

A combinatorial approach has been used to rapidly identify cyclic d,l-alpha-peptide hexamer sequences that exert biocidal activity towards both methicillin-resistant Staphylococcus aureus (MRSA) and E. coli bacteria, as well as the marine algae Ulva linza and Navicula perminuta. Evaluation of the effects against marine algae was facilitated by the development of a reliable, automated assay for toxicity, which should be of general utility for biofouling investigations. While the selective toxicity of cyclic D,L-alpha-peptides towards bacteria has been proven to be highly sensitive to minor changes in amino acid composition, this study demonstrates that this phenomenon extends to eukaryotic species as well, despite their significant structural differences. In performing toxicity assays on both prokaryotic and eukaryotic organisms in parallel, we have discovered examples of six-residue cyclic D,L-alpha-peptide sequences with either broad-spectrum or highly selective biocidal activities. Sequence [KWFFFH] (underlined amino acid abbreviations represent D-amino acid residues) was found to display 100-fold selectivity towards U. linza, demonstrating that the approach described herein may help lead to the development of new biofouling tools which are not generally toxic to all organisms, but rather specifically target microbial agents of interest.     

A survey of contingency factors affecting the validation of end-user spreadsheet-based decision support systems

Decision support systems have become widespread in recent years. However, most of these systems are not carefully validated and this has led in some cases to serious errors. One of the principal reasons for the lack of validity is the lack of an operationalised validation methodology. A simplified validity framework has already been developed by the authors as the first part of a 3-phase approach towards devising a practical validation methodology. This paper describes the second phase, reporting as it does on a survey that has been undertaken to unearth the contingency factors that influence how the process of validation, employing the validity framework, will be carried out for a particular kind of decision support system—one involving a spreadsheet model.     

A one-pot sulfide to sulfone oxidation with m-chloroperoxybenzoic acid and sodium permanganate

A synthetic strategy towards [2-(1H-indol-5-yl)-6-morpholin-4-ylpyrimidin-4-yl]methylsulfones is described, utilising m-chloroperoxybenzoic acid and sodium permanganate in a one-pot sulfide-sulfone oxidation.     

Coulomb excitation of radioactive 20, 21Na

The low-energy structures of the radioactive nuclei ^{20, 21}Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ～ 5×10⁶ ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 ^natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for $ \gamma$ -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For ²¹Na , Coulomb excitation from the 3/2⁺ ground state to the first excited 5/2⁺ state was observed, while for ²⁰Na , Coulomb excitation was observed from the 2⁺ ground state to the first excited 3⁺ and 4⁺ states. For both beams, B ( $ \lambda$ L) values were determined using the 2⁺ $ \rightarrow$ 0⁺ de-excitation in ⁴⁸Ti as a reference. The resulting B(E2) ↓ value for ²¹Na is 137±9 e^2fm^4, while the resulting B( $ \lambda$ L) ↓ values for ²⁰Na are 55±6 e^2fm^4 for the 3⁺ $ \rightarrow$ 2⁺ , 35.7±5.7 e^2 fm^4 for the 4⁺ $ \rightarrow$ 2⁺ , and 0.154±0.030 μ_N^2 for the 4⁺ $ \rightarrow$ 3⁺ transitions. This analysis significantly improves the measurement of the ²¹Na B(E2) value, and provides the first experimental determination of B( $ \lambda$ L) values for the proton dripline nucleus ²⁰Na .-1     

Evaluation of Light Fluence Distribution Using an IR Navigation System for HPPH-mediated Pleural Photodynamic Therapy (pPDT)

Uniform light fluence distribution for patients undergoing photodynamic therapy (PDT) is critical to ensure predictable PDT outcomes. However, current practice when delivering intrapleural PDT uses a point source to deliver light that is monitored by seven isotropic detectors placed within the pleural cavity to assess its uniformity. We have developed a real-time infrared (IR) tracking camera to follow the movement of the light point source and the surface contour of the treatment area. The calculated light fluence rates were matched with isotropic detectors using a two-correction factor method and an empirical model that includes both direct and scattered light components. Our clinical trial demonstrated that we can successfully implement the IR navigation system in 75% (15/20) of the patients. Data were successfully analyzed in 80% (12/15) patients because detector locations were not available for three patients. We conclude that it is feasible to use an IR camera-based system to track the motion of the light source during PDT and demonstrate its use to quantify the uniformity of light distribution, which deviated by a standard deviation of 18% from the prescribed light dose. The navigation system will fail when insufficient percentage of light source positions is obtained (<30%) during PDT.     

Multiple classifier architectures and their application to credit risk assessment

Multiple classifier systems combine several individual classifiers to deliver a final classification decision. In this paper the performance of several multiple classifier systems are evaluated in terms of their ability to correctly classify consumers as good or bad credit risks. Empirical results suggest that some multiple classifier systems deliver significantly better performance than the single best classifier, but many do not. Overall, bagging and boosting outperform other multi-classifier systems, and a new boosting algorithm, Error Trimmed Boosting, outperforms bagging and AdaBoost by a significant margin.