Effects of urbanization on the aquatic fauna of the Line Creek watershed, Atlanta—a satellite perspective

Impervious surface area (ISA) was derived for a period from 1979 to 1997 from Landsat MSS and TM data for the Line Creek watershed that lies to the south of the city of Atlanta, GA. The change in ISA is presented as an ecological indicator to examine the cumulative water resource impacts on mussel population in three sub-watersheds of Line Creek—namely, Line, Flat, and Whitewater creeks. The satellite analysis shows that ISA expansion occurred substantially from 1987 to 1997 and is predominantly in industrial, commercial, and shopping center (ICS) complexes but also in smaller lot-size residential development. Evidence of mussel habitat degradation is indicated and loss of species (in the region of 50 to 70%) is present in areas where ISA expansion is observed—specifically in ICS complex development in and around Peachtree City that drains directly into the Line and Flat creeks. This is in marked contrast to Whitewater Creek where overall development of ISA is less and no major loss of mussel species is observed.     

Partial order reduction for state/event LTL with application to component-interaction automata

Software systems assembled from a large number of autonomous components become an interesting target for formal verification due to the issue of correct interplay in component interaction. State/event LTL (Chaki et al. (2004, 2005) [1] and [2]) incorporates both states and events to express important properties of component-based software systems.The main contribution of this paper is a partial order reduction technique for verification of state/event LTL properties. The core of the partial order reduction is a novel notion of stuttering equivalence which we call state/event stuttering equivalence. The positive attribute of the equivalence is that it can be resolved with existing methods for partial order reduction. State/event LTL properties are, in general, not preserved under state/event stuttering equivalence. To this end we define a new logic, called weak state/event LTL, which is invariant under the new equivalence.To bring some evidence of the method’s efficiency, we present some of the results obtained by employing the partial order reduction technique within our tool for verification of component-based systems modelled using the formalism of component-interaction automata (Brim et al. (2005) [3]).     

Flash memory efficient LTL model checking

As the capacity and speed of flash memories in form of solid state disks grow, they are becoming a practical alternative for standard magnetic drives. Currently, most solid-state disks are based on NAND technology and much faster than magnetic disks in random reads, while in random writes they are generally not.So far, large-scale LTL model checking algorithms have been designed to employ external memory optimized for magnetic disks. We propose algorithms optimized for flash memory access. In contrast to approaches relying on the delayed detection of duplicate states, in this work, we design and exploit appropriate hash functions to re-invent immediate duplicate detection.For flash memory efficient on-the-fly LTL model checking, which aims at finding any counter-example to the specified LTL property, we study hash functions adapted to the two-level hierarchy of RAM and flash memory. For flash memory efficient off-line LTL model checking, which aims at generating a minimal counterexample and scans the entire state space at least once, we analyze the effect of outsourcing a memory-based perfect hash function from RAM to flash memory.Since the characteristics of flash memories are different to magnetic hard disks, the existing I/O complexity model is no longer sufficient. Therefore, we provide an extended model for the computation of the I/O complexity adapted to flash memories that has a better fit to the observed behavior of our algorithms.     

Using Assumptions to Distribute Alternation Free μ-Calculus Model Checking

In this work we extend the approach used in [6] to perform distributed-memory AFMC model checking. The part of a system held in one computer is modeled as a Kripke structure with border states. Moreover, we use assumptions about the truth of a formula in each state. Each process then repeatedly executes a slight modification of a standard sequential algorithm and exchanges its results with other processes. In the paper we define the AFMC semantics for structures with border states and assumptions, present the distributed algorithm and show the main ideas behind the proof of its correctness. Complexity and experimental results are provided as well.     

Introductory paper

This special section is devoted to a selection of contributions originally presented at the 1st International Workshop on Parallel and Distributed Model Checking (PDMC 2002), which took place in Brno, Czech Republic in September 2002 as a satellite event of the 13th conference on concurrency theory (CONCUR 2002). The growing importance of automated formal verification in industry is driving a growing interest in those aspects that have a direct impact on its applicability to real-world problems. One of the main technical challenges is in devising tools that allow one to handle large state spaces. In the last several years numerous approaches to solving this problem have been developed. Recently there has been increasing interest in parallelizing and distributing verification techniques. Papers that appear in this special section provide an interesting sampling of typical approaches in this direction.     

Accurate numerical modeling of microstrip junctions and discontinuities

A general numerical solver for analyzing microstrip geometries of rectangular shape is presented in this paper. The analytical foundation of this solver is based on an integral equation approach which we formulate in the spatial domain. The unknown surface current on the microstrip is solved by the method of moments using 2D rectangular pulses as the expansion functions. Transmission-line modeling is then used to parameterize a given microstrip junction or discontinuity. Aided by a graphics interface, this solver can analyze complex structures without incurring additional analytical complexity. We illustrate the accuracy and versatility of our solver by applying it to several different microstrip discontinuities ranging from a single-stub to an interdigitated capacitor.     

Pseudo-outbreak of septicemia due to rapidly growing mycobacteria associated with extrinsic contamination of culture supplement

Between April and December 1994, 23 blood cultures from human immunodeficiency virus-infected patients grew rapidly growing mycobacteria suspected to be Mycobacterium chelonae at a hospital in New Jersey. The isolates were later identified as M. abscessus. Several bacterial species, including M. abscessus, were cultured from an opened multidose supplement vial (BBL Septi-Chek AFB Supplement) that had been used for mycobacterial blood cultures. The M. abscessus isolates from case patients and the supplement vial had identical multilocus enzyme electrophoresis and antimicrobial susceptibility patterns. Finding a contaminated vial of supplement, together with the lack of a distinct syndrome in case patients, was consistent with a pseudo-outbreak.     

Effects of habitat suitability on the survival of relocated freshwater mussels

Freshwater mussels are often relocated from existing beds for both conservation and management reasons. In this study, we empirically tested whether the habitat type at the destination site was important in predicting the success of mussel relocation. In 1993, four species of freshwater mussels were relocated in the Apalachicola River in Florida, into three distinct habitat types: stable sand, limestone/sand and cobble. The conditional probability of survival of relocated mussels varied by species and habitat. Two species were considered habitat specialists, one species was considered a habitat generalist and recovery rates for the fourth species were too low to assess habitat preferences. We show empirically that microhabitat is important in the survival of relocated mussels and that the habitat-specific criteria for relocation is species specific. These results suggest that survival of relocated mussels can be enhanced if species-specific site selection criteria are developed using quantitative information. © 1997 John Wiley & Sons, Ltd.     

Overdiagnosis of major psychiatric disorders in individuals with substance use disorders and personality disorders: the downside of the Woodruff principle

Major vascular injury can result during use of the Ilizarov technique for lower extremity limb lengthening. Vascular reconstruction may be accomplished while leaving the external fixation ring in place. Continued distraction is made possible by leaving sufficient redundancy in the vascular graft.