Efficient local strategies for vaccination and network attack

We study how a fraction of a population should be vaccinated to most efficiently top epidemics. We argue that only local information (about the neighborhood of specific vertices) is usable in practice, and hence we consider only local vaccination strategies. The efficiency of the vaccination strategies is investigated with both static and dynamical measures. Among other things we find that the most efficient strategy for many real-world situations is to iteratively vaccinate the neighbor of the previous vaccinee that has most links out of the neighborhood

The Primary Pretenders

We call a composite number q such that there exists a positive integer b with b^p == b (mod q) a prime pretender to base b. The least prime pretender to base b is the primary pretender q_b. It is shown that there are only 132 distinct primary pretenders, and that q_b is a periodic function of b whose period is the 122-digit number 19568584333460072587245340037736278982017213829337604336734362- 294738647777395483196097971852999259921329236506842360439300.Comment: 7 page

Geomorphic evidence for ancient seas in west Deuteronilus Mensae, Mars-1: Regional geomorphology

The fretted terrain in west Deuteronilus Mensae consists of extensive cratered upland penninsulas or isolated plateaus cut by long, finger-like canyons typically 10 to 20 km wide and upwards of 300 km long. The longest of these canyons trend roughly north-south to north-northeast, which may reflect some local structural and/or topographic control. At least three geomorphic zones roughly parallel to the lowland/upland boundary, suggestive of increasing modification northward, can be recognized on the fretted region of the region. The southern-most zone (zone A) consists of sharply defined fretted terrain. The middle zone (zone B) consists of well defined fretted terrain in which the plateau surfaces appear smoother, with a somewhat darker and much less varied albedo surface than those of zone A. The northern-most zone (zone C) consists of rounded or softened fretted terrain. The zones were interpreted as surface exposures of successively lower stratigraphic units

Geomorphic evidence for ancient seas on Mars

Geomorphic evidence is presented for ancient seas on Mars. Several features, similar to terrestrial lacustrine and coastal features, were identified along the northern plains periphery from Viking images. The nature of these features argues for formation in a predominantly liquid, shallow body of standing water. Such a shallow sea would require either relatively rapid development of shoreline morphologies or a warmer than present climate at the time of outflow channel formation

Curvilinear ridges and related features in southwest Cydonia Mensae, Mars

Examined is a region on Mars in southwest Cydonia Mensae (32 deg lat., 17 deg long.) just northwest of the lowland/upland boundary escarpment. The dominant morphological features in this region are the clusters of large massifs and plateau outliers (PI), knobby material (K), and smooth lowland plains (Ps). Surrounding the clusters and linking many isolated knobs is a system of curvilinear ridges and arcuate terrain boundaries which tend to separate the massifs and knobs from the smooth plains. Curvilinear ridges are arcuate to nearly linear and smoother in plan than wrinkle ridges and show no apparent correlation with regional structural grain. They are typically 5 to 10 km long but can range from as little as 2 or 3 km to greater than 50 km long. The widths vary from about 100 m to as much as 2 km. Curvilinear ridges are most numerous within 100 km of the lowland/upland boundary escarpment and are associated with massifs and knobby terrain. Arcuate terrain boundaries appear between units of different apparent albedo or arcuate breaks in slope

Geomorphic evidence for ancient seas in west Deuteronilus Mensae, Mars-2: From very high resolution Viking Orbiter images

Very high resolution Viking Orbiter images of the Martian surface, though rare, make it possible to examine specific areas at image scales approaching those of high altitude terrestrial aerial photographs. Twenty three clear images lie within west Deuteronilus Mensae. The northernmost images which constitute an almost unbroken mosaic of the west wall of a long fingerlike canyon are examined. Morphological details on the plateau surface within zone B, not detectable at low resolution, make it possible to divide the zone into two distinct subzones separated by an east-west escarpment. The morphology of the canyon floor is described in detail

Occurrence of the Acanthocephalan Leptorhynchoides thecatus in Slimy Sculpins—A New Host Record

A new host (Cottus cognatus) for adults of the acanthocephalan Leptorhynchoides thecatus (Linton) is reported. Of 176 slimy sculpins examined from eastern Lake Michigan, 93% were infected by L. thecatus. The number of L. thecatus infecting slimy sculpins was directly related to size of fish. Mean number of L. thecatus per fish was 17 for males, 10 for females, and 3 for immatures. One male was infected with 132 L. thecatus.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141417/1/tafs0142.pd

Gilling in Trap‐Net Pots and Use of Catch Data to Predict Lake Whitefish Gilling Rates

Gilling of lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) in trapnet pots was investigated for three commercial nets set during the fall of 1980 in northern Lake Huron. Approximately 73% of observed giliing occurred as nets were being lifted. Consequently, high percentages of gilled fish were alive when fishermen harvested their catch. More than two‐thirds of the gilled fish were located in side netting, while smaller proportions of gilled fish were found in the back, front, top, and bottom of the pot. A regression model was developed to predict the number of lake whitefish gilled based on total catch. Independent variables for the statistically significant (P < 0.001) model were the number of lake whitefish caught and the square root of the number of lake trout in the pot. Lake whitefish schooling behavior associated with the approach of spawning season was regarded as an important factor in explaining gilling rates. The number of gilled whitefish could be reduced by increasing the frequency of net lifts if it were found to be economically feasible.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141650/1/nafm0294.pd