Punctate and early confluent to confluent WMH show distinguishable differences in their spatial distribution within a normal elderly population. The pattern of punctate WMH is probably a consequence of mixed etiologies. Preferential localization of the more confluent WMH with arterial watershed areas implies a stronger ischemic component in their development.

Children today are more exposed to cyberspace and cyber threats than any of the previous generations. Due to the ever-evolving nature of digital technologies, devices like cell phones and tablets are more accessible to both young and old. Although technological advancements create many opportunities to its users, it also exposes them to many different threats. Young users are especially vulnerable, as they are rarely educated about these threats and how to protect themselves against them. One possible solution to this problem is to employ serious games as an educational tool to introduce concepts relating to cybersecurity and overall digital wellness on a level that is appropriate to a younger audience. This paper, therefore, presents the development of a mobile serious game to promote the digital wellness and foster cybersecurity awareness of pre-school children by incorporating existing literature in a new format. In order to assess its appropriateness as an educational tool, the resulting serious game was subjected to expert review with a focus on its value of conveying security and wellness concepts at the proper level, thereby promoting children's safety in the digital world.

Riometer recordings of cosmic radio noise in polar regions show a variability in sidereal variationduring subsequent quiet days. The fitting of a low-order Fourier series to maximum density points in sidereal time intervals has the advantage that as few as 7 days may be used to determine a quiet day curve. Quiet day curves determined for periods of 7 days in a sliding sequence show a short-term variability of about 0.13 dB in signal strength. For periods of 30 days this variability is 10 times less. Absorption events should be obtained from the quiet day curve appropriate for the period of the event. Absorption obtained from quiet day curves determined for maximum density points will be about 0.05 dB less for 30 MHz than using the inflection point method. 1159 Res., 92, 5961-5968, 1987.

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[1] A method for the determination of riometer quiet day curves which is based on the filtering of a discrete two-dimensional function or matrix has been proposed. The two dimensions of the matrix are siderial time and day number, with each row of the matrix representing one siderial day. The filtering is done in the Fourier domain using a low-pass filter. With a low-pass filter the low frequency Fourier coefficients are retained, while the high frequency Fourier coefficients are discarded. The highest Fourier coefficient that is retained is the cutoff frequency of the filter. In this paper the filter cutoff frequencies are derived directly from the antenna reception pattern as well as from the data itself. A number of methods can be used to infer a cutoff frequency from the data; however, only a number of entropy based methods are investigated in this paper.