"It is possible he is a kind of nut": how the tobacco industry quietly promoted Dr William Whitby

Dr William Whitby was a general practitioner in Sydney who, from 1978 until about 1987, self published two books extolling the virtues of smoking and ridiculing anti-smoking claims. Privately the tobacco industry regarded him as "nutty", while nonetheless believing that his views should be promoted. They quietly supported him by distributing his book, offering legal advice, and persuading him to take media training. Many Australians would have been exposed to his views.     

A Low-Power Integrated Bioamplifier With Active Low-Frequency Suppression

We present in this paper a low-power bioamplifier suitable for massive integration in dense multichannel recording devices. This bioamplifier achieves reduced-size compared to previous designs by means of active low-frequency suppression. An active integrator located in the feedback path of a low-noise amplifier is employed for placing a highpass cutoff frequency within the transfer function. A very long integrating time constant is achieved using a small integrated capacitor and a MOS-bipolar equivalent resistor. This configuration rejects unwanted low-frequency contents without the need for input RC networks or large feedback capacitors. Therefore, the bioamplifier high-input impedance and small size are preserved. The bioamplifier, implemented in a 0.18-mum CMOS process, has been designed for neural recording of action potentials, and optimised through a transconductance-ef-ficiency design methodology for micropower operation. Measured performance and results obtained from in vivo recordings are presented. The integrated bioamplifier provides a midband gain of 50 dB, and achieves an input-referred noise of 5.6 muVrms. It occupies less than 0.050 mm² of chip area and dissipates 8.6 muW.     

DNA double-strand break repair: a theoretical framework and its application

DNA double-strand breaks (DSBs) are formed as a result of genotoxic insults, such as exogenous ionizing radiation, and are among the most serious types of DNA damage. One of the earliest molecular responses following DSB formation is the phosphorylation of the histone H2AX, giving rise to γH2AX. Many copies of γH2AX are generated at DSBs and can be detected in vitro as foci using well-established immuno-histochemical methods. It has previously been shown that anti-γH2AX antibodies, modified by the addition of the cell-penetrating peptide TAT and a fluorescent or radionuclide label, can be used to visualize and quantify DSBs in vivo. Moreover, when labelled with a high amount of the short-range, Auger electron-emitting radioisotope, ¹¹¹In, the amount of DNA damage within a cell can be increased, leading to cell death. In this report, we develop a mathematical model that describes how molecular processes at individual sites of DNA damage give rise to quantifiable foci. Equations that describe stochastic mean behaviours at individual DSB sites are derived and parametrized using population-scale, time-series measurements from two different cancer cell lines. The model is used to examine two case studies in which the introduction of an antibody (anti-γH2AX-TAT) that targets a key component in the DSB repair pathway influences system behaviour. We investigate: (i) how the interaction between anti-γH2AX-TAT and γH2AX effects the kinetics of H2AX phosphorylation and DSB repair and (ii) model behaviour when the anti-γH2AX antibody is labelled with Auger electron-emitting ¹¹¹In and can thus instigate additional DNA damage. This work supports the conclusion that DSB kinetics are largely unaffected by the introduction of the anti-γH2AX antibody, a result that has been validated experimentally, and hence the hypothesis that the use of anti-γH2AX antibody to quantify DSBs does not violate the image tracer principle. Moreover, it provides a novel model of DNA damage accumulation in the presence of Auger electron-emitting ¹¹¹In that is supported qualitatively by the available experimental data.     

A simplified method for retrieval of ground level reflectance of targets from airborne video imagery

This paper describes an efficient method for retrieval of ground reflectance characteristics of targets from calibrated multispectral airborne video data for routine operational airborne missions. The method uses a simplified atmospheric scattering model in combination with a dark-object subtraction procedure to estimate the effect of the atmosphere in the path between the target and the sensor, as well as the adjacent environmental effect, on the radiation signal received by an airborne sensor. The simplicity of the atmospheric scattering model is maintained by the assumption that the air density within the targetsensor path in the lower atmosphere is sufficiently uniform for operations of the Charles Sturt University's (CSU) Multispectral Airborne Video System (MAVS). The MAVS acquires imagery in blue, green, red and near-infrared (NIR) narrow spectral bands. The MAVS is radiometrically calibrated and has a consistent radiometric response in-flight. An important feature of the new method is the coupling of the image based brightness data (DN) of a dark-object and the system radiometric calibration coefficients to determine the path reflectance and the environmental reflectance of the target. The sum of the path reflectance and the environment reflectance is known as haze reflectance. The haze reflectance indicates the amount of atmospheric haze in the airborne imagery. The simplified atmospheric model is then employed to determine the actual ground reflectance of the targets using the haze subtracted apparent (total) reflectance of the target at the altitude of the airborne sensor. The apparent reflectance of the target at the sensor altitude is obtained directly from the image based DN data and the system radiometric calibration coefficients. An interesting aspect of this simplified method is that an estimate of the environmental reflectance can be obtained as a by-product of the atmospheric haze calculation using a dark-object subtraction technique. The retrieved ground reflectance characteristics from calibrated MAVS imagery are now being used routinely for remote quantitative monitoring of agricultural and environmental targets.     

Derivation of sky-view factors from lidar data

The use of lidar (light detection and ranging), an active light-emitting instrument, is becoming increasingly common for a range of potential applications. Its ability to provide fine-resolution spatial and vertical-resolution elevation data makes it ideal for a wide range of studies. This article demonstrates the ability of lidar data to measure sky-view factors (ψ_s). The lidar data are used to generate a spatial map of ψ_s, which are then compared against photographically derived ψ_s at selected locations. At each location, three near-surface elevation measurements were taken and compared with collocated lidar-derived estimates. Generally a good agreement was found between the two methodologies, although with decreasing ψ_s, the lidar technique tended to overestimate ψ_s. This can be attributed in part to the spatial resolution of the lidar sampling. Nevertheless, airborne lidar systems can easily map ψ_s over a large area, potentially improving the use of such data in atmospheric and meteorological models.     

The JERS Amazon Multi-season Mapping Study (JAMMS): Observation strategies and data characteristics

The Japanese Earth Resources Satellite (JERS-1) Amazon Multiseason Mapping Study (JAMMS), part of the Global Rain Forest Mapping (GRFM) project led by the National Space Development Agency of Japan (NASDA), had an ambitious agenda to map the entire Amazon river floodplain (and surrounding areas) twice at high resolution. The observation strategy carried out by NASDA for the JAMMS project and the other elements of the GRFM project (1995-1997) constituted the first time that a spaceborne Synthetic Aperture Radar (SAR) successfully implemented a continental scale, coordinated seasonal mapping campaign. This observation strategy, chosen around the flooding cycle of the major river systems, was designed to provide the first high-resolution measurement of inundation extent by the Amazon river and its tributaries. In order for the scientific community at large to be able to exploit this dataset, the characteristics of the data (resolution, radiometric and geometric calibration, coverage, and ability to be mosaicked) must be well understood. We find that the quantization of the Alaska SAR Facility (ASF) imagery impacts the range of backscatter values that may be observed, in contrast to the NASDA processed imagery. The noise equivalent σ 0 is -15 dB at worst, but improves to about -20 dB at the centre of the swath. The resolution of the ASF imagery is slightly worse than that processed by NASDA. The initial geolocation accuracy of the ASF processed imagery is quite poor, but may be improved during the mosaicking process. The relative radiometric calibration of the data may be improved to about 0.2 dB by comparing the calibration of overlapping imagery, and through a careful analysis of cross-track trends in the data.