Given the present pandemic caused by the severe acute respiratory syndrome coronavirus 2 or SARS-CoV-2 virus, the authors tried fitting existing models for the daily loss of lives. Based on data reported by Worldometers on the initial stages (first wave) of the pandemic for countries acquiring the disease, the authors observed that the logarithmic rendering of their data hinted the response of a first-order process to a step function input, which may be modeled by a three-parameters function, as described in this paper. This model was compared against other similar, log(N)-class of models that are non-compartmental type (such as the susceptible, infected, and removed, or SIR models), obtaining good fit and statistical comparison results, where N denotes the cumulative number of daily presumed deaths. This simple first-order response model can also be applied to bacterial and other biological growth phenomena. Here we describe the model, the numerical methods utilized for its application to actual pandemic data, and the statistical comparisons with other models which shows that our simple model is comparatively outstanding, given its simplicity. While researching the models available, the authors found other functions that can also be applied, with extra parameters, to be described in follow-on articles.

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The pyroelectric effect has been characterized for single-pixel elements consisting of strontium bismuth tantalate (SBT) ferroelectric material as the sensing element. The pixels include also a thermal insulating layer and an infrared (IR) absorber layer. These MEMS-less devices are operated in active mode, a technique that eliminates the need for a radiation chopper found in passive pyroelectric IR imagers. Test results of the SBT pixels of dimensions 7.5 µm × 7.5 µm to 200 µm × 200 µm have shown high endurance to polar cycling, high responsivity values, and very low noise-equivalent temperature difference for focal plane array applications. This paper describes and analyses the results of precursor 2 × 2 arrays using discrete sensing elements, the active detection mechanism, and its unique read-out electronics. A second-generation 32 × 32 pixels array being implemented to demonstrate the performance of a 1k-pixel array as precursor to larger size arrays is also described. The active mode detection, in addition to eliminating the use of a chopper, enables the dynamic partition of the array into pixel domains in which the pixel sensitivities in each domain can be adjusted independently. This unique feature in IR detection is not readily found in other types of IR imagers and can be applied to the simultaneous tracking of diverse contrast objects. By controlling the absorber material thickness, the arrays can be optimized for maximum response at specified wavelengths by means of quarter-wavelength interferometric technique.

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