Crseharacterization of land surface thermal structure from NOAA-AVHRR data over a northern ecosystem

This paper focuses on the estimation and analysis of surface thermal parameters (emissivities and surface temperatures) in a nordic environment (Québec, Canada). The land cover in this region varies from boreal forest in the south to tundra in the north. The thermal parameters are estimated from two variants of a new model that combines the radiances of the short wave infrared (SWIR) spectral band [advanced very high resolution radiometer (AVHRR) channel 3: 3.55–3.93 μm] and the thermal bands (AVHRR channel 4: 10.5–11.5 μm; and AVHRR channel 5: 11.5–12.5 μm). The study, carried out for images acquired on different dates, reveals that, in most situations, the two approaches allow the separation of emissivities and surface temperatures. Analysis of the variations of the estimated emissivities in relation to surface patterns shows that they are slightly variable in spectral bands 4, and 5, with values generally greater than 0.95. Variations are more important in the SWIR channel, where values less than 0.90 appear, especially in urban areas. In general, surface emissivities increase with the density of the vegetation cover. Moreover, for densely vegetated areas, SWIR surface reflectivities, which can be derived from emissivities, appear to be well correlated with the reflectivities of the AVHRR visible channel. As with emissivities, variations of the estimated land surface temperatures (LST) in relation to vegetation density, characterized by the normalized difference vegetation index (NDVI), were considered. The relations between the two parameters (LST and NDVI) show essentially two opposite directions of linear variations (positive and negative correlations). In the light of the main results obtained, the synergistic use of the different spectral regions (visible, near, mid-, and thermal infrareds) could be very useful in the parameterization of boreal ecosystems.     

Comparison of the Acoustic and Mechanical Signatures of Two Cellular Crunchy Cereal Foods at Various Water Activity Levels

Cheese balls and croutons at various water activity levels (0·11–0·75) were compressed between parallel metal plates using a Universal testing machine and their acoustic emissions were recorded at compact disc quality (sampling rate of 44·1 kHz). The sound wave record (up to about 2 MB) had high intensity bursts at irregular intervals. These records were compressed after the background noise had been filtered out to produce files of less than 48 kB. The compressed signatures were characterised by their mean and peak amplitude, two measures of the sound emission intensity, and by the amplitude's standard deviation and the mean magnitude of the power spectrum, two measures of the acoustic signature complexity. All four parameters could be used to monitor the plasticisation effect of water. Although their magnitudes were correlated, they did not always change in unison upon moisture sorption. The standard deviation and mean magnitude of the power spectrum of the compressed acoustic signatures were only broadly correlated with their correspondents in the normalised mechanical signatures primarily because they were not determined from the same particles and because the latter, for technical reasons, were sampled at the low rate of 6 Hz.     

On modeling the irregular fluctuations in microbial counts

Daily or other periodic microbial counts in many foods, particularly ground meats, poultry, and raw milk, show an irregular fluctuating pattern. The cause of the fluctuations is the interplay of many random factors that tend to promote or inhibit microbial growth. Therefore, the actual size of a microbial population can vary randomly around a typical level or around a trend determined, for example, by seasonal variations or changing sanitary conditions. Fluctuations around a fixed level can often be modeled as a sequence of independent counts having a lognormal or other parametric distribution. The independence of the counts and the type of distribution can be established by standard statistical tests. Once selected, the distribution function can be used to estimate the probability of encountering a population in any given size range. The model can be modified to describe sequences that include zero counts, which are the result of the organisms' absence, or of the failure of the method to detect them. In the case of fluctuations around a trend, a modified version of the model can be used to estimate the probability of deviations from the trend. A more thorough modification is required in order to account for fluctuating patterns that include outbursts of appreciable duration, like those caused by massive contamination of a water reservoir.     

Surface transformations of carbon (graphene, graphite, diamond, carbide), deposited on polycrystalline nickel by hot filaments chemical vapour deposition

The deposition of carbon has been studied at high temperature on polycrystalline nickel by hot filaments activated chemical vapor deposition (HFCVD). The sequences of carbon deposition are studied by surface analyses: Auger electron spectroscopy (AES), electron loss spectroscopy (ELS), X-ray photoelectron spectroscopy (XPS) in a chamber directly connected to the growth chamber. A general scale law of the (C/Ni) intensity lines is obtained with a reduced time. Both, shape analysis of the AES C KVV line and the C1s relative intensity suggest a three-step process: first formation of graphene and a highly graphitic layer, then multiphase formation with graphitic, carbidic and diamond-like carbon and finally at a critical temperature that strongly depends on the pretreatment of the polycrystalline nickel surface, a rapid transition to diamond island formation. Whatever the substrate diamond is always the final product and some graphene layers the initial product. Moreover it is possible to stabilize a few graphene layers at the initial sequences of carbon deposition. The duration of this stabilization step is strongly depending however on the pre-treatment of the Ni surface.     

Impact of age and cognitive demand on lane choice and changing under actual highway conditions

Previous research suggests that drivers change lanes less frequently during periods of heightened cognitive load. However, lane changing behavior of different age groups under varying levels of cognitive demand is not well understood. The majority of studies which have evaluated lane changing behavior under cognitive workload have been conducted in driving simulators. Consequently, it is unclear if the patterns observed in these simulation studies carry over to actual driving. This paper evaluates data from an on-road study to determine the effects of age and cognitive demand on lane choice and lane changing behavior. Three age groups (20–29, 40–49, and 60–69) were monitored in an instrumented vehicle. The 40's age group had 147% higher odds of exhibiting a lane change than the 60's group. In addition, drivers in their 60's were less likely to drive on the leftmost lane compared to drivers in their 20's and 40's. These results could be interpreted as evidence that older adults adopt a more conservative driving style as reflected in being less likely to choose the leftmost lane than the younger groups and less likely to change lanes than drivers in their 40's. Regardless of demand level, cognitive workload reduced the frequency of lane changes for all age groups. This suggests that in general drivers of all ages attempt to regulate their behavior in a risk reducing direction when under added cognitive demand. The extent to which such self-regulation fully compensates for the impact of added cognitive demand remains an open question.     

Adaptive averaging for improved SNR in real-time coronary artery MRI

A technique has been developed for combining a series of low signal-to-noise ratio (SNR) real-time magnetic resonance (MR) images to produce composite images with high SNR and minimal artifact in the presence of motion. The main challenge is identifying a set of real-time images with sufficiently small systematic differences to avoid introducing significant artifact into the composite image. To accomplish this task, one must: 1) identify images identical within the limits of noise; 2) detect systematic errors within such images with sufficient sensitivity. These steps are achieved by evaluating the correlation coefficient (CC) between regions in prospective images and a template containing the anatomy of interest. Images identical within noise are selected by comparing the measured CC values to the theoretical distribution expected due to noise. Sensitivity for systematic error depends on the SNR of the CC (=SNR(CCmax)), which in turn depends on the noise, and the template size and structure. By varying the template size, SNR(CCmax) may be altered. Experiments on phantoms and coronary artery images demonstrate that the SNR(CCmax) necessary to avoid introducing significant artifact varies with the target composite SNR. The future potential of this technique is demonstrated on high-resolution (approximately 0.9 mm), reduced field-of-view real-time coronary images.     

Delayed gamma power measurement for sodium-cooled fast reactors

Previous works on pressurized water reactors show that the nitrogen 16 activation product can be used to measure thermal power. Power monitoring using a more stable indicator than ex-core neutron measurements is required for operational sodium-cooled fast reactors, in order to improve their economic efficiency at the nominal operating point. The fluorine 20 and neon 23 produced by (n,α) and (n,p) capture in the sodium coolant have this type of convenient characteristic, suitable for power measurements with low build-up effects and a potentially limited temperature, flow rate, burn-up and breeding dependence.This method was tested for the first time during the final tests program of the French Phénix sodium-cooled fast reactor at CEA Marcoule, using the ADONIS gamma pulse analyzer. Despite a non-optimal experimental configuration for this application, the delayed gamma power measurement was pre-validated, and found to provide promising results.