The aim of this paper is to model and evaluate the performance of intrusion detection systems (IDSs) facing black-hole and gray-hole attacks within wireless ad hoc networks (WANETs). The main performance metric of an IDS in a WANET can be defined as the mean time required for the IDS to detect an attack in the network. To evaluate this measure, two types of stochastic models called continuous t...

The initial transgressive phase at the Leg 144 Guyots is characterized by a typical association of sedimentary facies (from bottom to top): in situ weathered volcanic rocks; variegated clays, partly pyritic; gray clay, pyritic, homogeneous, or mottled; black clay, peaty, laminated, or bioturbated; and marine argillaceous limestone. Site 877 at Wodejebato Guyot represents the typical development...

The Imager for Mars Pathfinder (IMP) was a mast-mounted instrument on the Mars Pathfinder lander which landed on Mars’ Ares Vallis floodplain on July 4, 1997. During the 83 sols of Mars Pathfinders landed operations, the IMP collected over 16,600 images. Multispectral images were collected using twelve narrowband filters at wavelengths between 400 and 1000 nm in the visible and near infrared (V...

We measured the perceived lightness of target patches embedded in high dynamic range checkerboards. We independently varied the luminance of checks immediately surrounding the test and those remote from it. The data establish context transfer functions (CTFs) that characterize perceptual matches across checkerboard contexts. Several features of the CTFs are broadly consistent with previous rese...

Observations of the increased frequency of melanic forms in moths of the genus Biston in Great Britain after the industrial revolution lead to the development of the theory of Industrial Melanism. Nonetheless, arguments against that interpretation of the experimental evidence have polarized acceptance of the concept. New evidence based on diurnal butterflies is more credible because it involves...

BACKGROUND Allogeneic skin grafts onto C57BL/6 mice are rejected, and the rejected skin is replaced by surrounding skin with black hair. In contrast, syngeneic skin grafts are tolerated, and gray hair grows on the grafts. METHODS To explore the mechanism of gray hair growing on the tolerated skin grafts, we prepared full-thickness skin (2-cm square) autografts, 2 (2 cm + 2 cm) horizontal or v...

The oldest lightness illusion is called simultaneous contrast. A gray square placed on a black background appears lighter than an identical gray square placed on a white background. For over a hundred years, this illusion has been generally attributed to lateral inhibition or spatial filtering. Receptor cells stimulated by the gray square on the white background are strongly inhibited by nearby...