AUTOACTIVATION OF SPORE GERMINATION IN THE CELLULAR SLIME MOLD DICTYOSTELIUM DISCOIDEUM.

Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1979 .D245. Source: Dissertation Abstracts International, Volume: 40-04, Section: B, page: 1527. Thesis (Ph.D.)--University of Windsor (Canada), 1979

The density of critical percolation clusters touching the boundaries of strips and squares

We consider the density of two-dimensional critical percolation clusters, constrained to touch one or both boundaries, in infinite strips, half-infinite strips, and squares, as well as several related quantities for the infinite strip. Our theoretical results follow from conformal field theory, and are compared with high-precision numerical simulation. For example, we show that the density of clusters touching both boundaries of an infinite strip of unit width (i.e. crossing clusters) is proportional to $(\sin \pi y)^{-5/48}\{[\cos(\pi y/2)]^{1/3} +[\sin (\pi y/2)]^{1/3}-1\}$. We also determine numerically contours for the density of clusters crossing squares and long rectangles with open boundaries on the sides, and compare with theory for the density along an edge.Comment: 11 pages, 6 figures. Minor revision

THE PROGRAM PATHING TRUST MODEL FOR CRITICAL SYSTEM PROCESS AUTHORIZATION

Since computers are relied upon to run critical infrastructures – from nuclear power plants to electronic battlefield simulations – the concept of a “trusted” or tamperproof system has become even more important. Some applications have become so critical that it is imperative that they run as intended, without interference. The consequences of these systems not running as intended could be catastrophic. This research offers a solution for a key element for protecting these critical servers – validating process invocation sequences. The purpose of this research is to increase operating system security by detecting, validating, and enforcing process invocation sequences within a critical system. If the processes on a critical system are not those that are intended to run or support the critical system, or if a system is able to run processes in an unauthorized sequence, then the system is compromised and cannot be trusted. This research uses a computational theory approach to create a framework for a solution for the process invocation sequence problem. Using the Program Pathing Trust Model, a solution capable of identifying both valid and invalid process invocation sequences is developed

Strong succession in arbuscular mycorrhizal fungal communities.

The ecology of fungi lags behind that of plants and animals because most fungi are microscopic and hidden in their substrates. Here, we address the basic ecological process of fungal succession in nature using the microscopic, arbuscular mycorrhizal fungi (AMF) that form essential mutualisms with 70-90% of plants. We find a signal for temporal change in AMF community similarity that is 40-fold stronger than seen in the most recent studies, likely due to weekly samplings of roots, rhizosphere and soil throughout the 17 weeks from seedling to fruit maturity and the use of the fungal DNA barcode to recognize species in a simple, agricultural environment. We demonstrate the patterns of nestedness and turnover and the microbial equivalents of the processes of immigration and extinction, that is, appearance and disappearance. We also provide the first evidence that AMF species co-exist rather than simply co-occur by demonstrating negative, density-dependent population growth for multiple species. Our study shows the advantages of using fungi to test basic ecological hypotheses (e.g., nestedness v. turnover, immigration v. extinction, and coexistence theory) over periods as short as one season

MAC OS X Forensics: Password Discovery

OS X provides a password-rich environment in which passwords protect OS X resources and perhaps many other resources accessed through OS X. Every password an investigator discovers in an OS X environment has the potential for use in discovering other such passwords, and any discovered passwords may also be useful in other aspects of an investigation, not directly related to the OS X environment. This research advises the use of multiple attack vectors in approaching the password problem in an OS X system, including the more generally applicable non-OS X-specific techniques such as social engineering or well-known password cracking techniques such as John the Ripper or other versions of dictionary attacks and Rainbow table attacks. In some successful approaches the components of the attack vector will use more OS X specific techniques such as those described here: application-provided password revealing functions, a Javascript attack, an “Evil Website” attack, system file scavenging, exploitation of the keychain, and an OS X install disk attack. Keywords: OS X, password, password discovery, social engineering, sleepimage, keychai

Fungal community assembly in drought-stressed sorghum shows stochasticity, selection, and universal ecological dynamics.

Community assembly of crop-associated fungi is thought to be strongly influenced by deterministic selection exerted by the plant host, rather than stochastic processes. Here we use a simple, sorghum system with abundant sampling to show that stochastic forces (drift or stochastic dispersal) act on fungal community assembly in leaves and roots early in host development and when sorghum is drought stressed, conditions when mycobiomes are small. Unexpectedly, we find no signal for stochasticity when drought stress is relieved, likely due to renewed selection by the host. In our experimental system, the host compartment exerts the strongest effects on mycobiome assembly, followed by the timing of plant development and lastly by plant genotype. Using a dissimilarity-overlap approach, we find a universality in the forces of community assembly of the mycobiomes of the different sorghum compartments and in functional guilds of fungi