Theory and Techniques for Synthesizing a Family of Graph Algorithms

Although Breadth-First Search (BFS) has several advantages over Depth-First Search (DFS) its prohibitive space requirements have meant that algorithm designers often pass it over in favor of DFS. To address this shortcoming, we introduce a theory of Efficient BFS (EBFS) along with a simple recursive program schema for carrying out the search. The theory is based on dominance relations, a long standing technique from the field of search algorithms. We show how the theory can be used to systematically derive solutions to two graph algorithms, namely the Single Source Shortest Path problem and the Minimum Spanning Tree problem. The solutions are found by making small systematic changes to the derivation, revealing the connections between the two problems which are often obscured in textbook presentations of them.Comment: In Proceedings SYNT 2012, arXiv:1207.055

Visualization of acoustic intensity vector fields using scanning measurement techniques

Sound propagation paths are not always well understood mainly because of the complex nature of the source or the environment. A direct method to capture the sound energy flow throughout a room is to measure the three-dimensional sound intensity distribution across space. In the past years, several studies have been carried out using step by step measurements with a three-dimensional intensity probe consisting of a sound pressure transducer and three orthogonal particle velocity sensors. The probe’s ability to measure even in highly reverberant environments and its small size are key features required for numerous applications. However, punctual measurements are time-consuming, especially when a large number of measurement positions are evaluated. The use of advanced scanning measurement techniques, such Scan & Paint, allows for the gathering of data across a time stationary sound field in a fast and efficient way, using a single sensor and webcam only. The acoustic signals are acquired manually by moving a probe across a measurement plane whilst filming the event with a camera. In the post-processing stage, the sensor position is extracted and then used for linking a segment of the signal acquired to a certain position of the space. In this manner, the overall measurement time is reduced from hours to minutes. In this paper, the acoustic intensity vector fields of several complex examples are investigated; revealing the acoustic energy flow of several vehicles, a loudspeaker in a room, and also the interaction between an absorbing sample and a reverberant sound field

A Day in the Life of Tort Law

What would one day\u27s worth of tort law look like? We usually receive our doses of the law in measures other than per diem: by the case, by the brief, by the article, or by the treatise. There is, of course, a unity in each of those units; each one collects only those authorities that bear upon certain focused aspects of the law. For example, an appellate brief or a law review article is often a compendium of cases dealing within a narrow topical range, cases drawn from a span of many different days, years, or even decades. One way to view the development of the common-law subjects, then, is to envision various lines or streams of cases, sometimes guided in their courses by statutory tributaries, flowing and joining into wide rivers: contract law, property law-- or tort law. But the law also grows by accretion. Each day, in courts across the nation, another layer is added to the law of torts. In some ways, as a construct, this is the antithesis of how we have learned to view the law. If a casebook is the order of the tort law, with two proximate cause cases from different eras neatly paired, then a single day represents the glorious chaos of tort: an auto accident in Pennsylvania, a products liability suit in Utah, a medical malpractice case in Connecticut. What might a one-day slice of American tort law reveal? I set out to find out. My quest would be artistic, not statistic. To construct the most accurate picture possible of one tort day would require a painstaking assembling of trial court records from thousands of local and county courthouses in all fifty states: a daunting task, and arguably not worth the mileage or postage. A more feasible approach is made possible by the ready availability of computerized searches in legal opinion databases. It is, of course, now possible to search for and compile all court opinions promulgated on a single, specific date, and to narrow the search further to a single area of law. Therefore, using the two best known computerized legal research services, I set out to discover one day\u27s worth of torts opinions, from the first light of dawn in Maine to the last rays on some Pacific coast courthouse

In Vitro and In Vivo Ocular Studies Using Herpes Simplex Virus Types 1 and 2

The biological properties of three HSV strains were characterized with reference to ocular disease in the rabbit. Two HSV-1 strains, 17 and McKrae, and the HSV-2 strain HG52 were studied and the following parameters were assessed; clinical disease; virulence; spontaneous shedding of HSV; induced shedding of HSV; neural latency; and corneal latency. Intratypic and intertypic differences were apparent. The HSV-l strain 17 was pathogenic to rabbit eyes and neuropathogenic with increasing titres of inoculum. It had a low frequency of spontaneous shedding and an intermediate frequency of induced shedding. The HSV-1 strain 17 was able to establish latent infections within trigeminal ganglia. The HSV-1 strain McKrae was pathogenic to rabbit eyes and particularly neuropathogenic. It had a high frequency of both spontaneous and induced viral shedding. The McKrae strain was able to establish latent infections within trigeminal ganglia but differed in maintaining a latent infection within the cornea. The HSV-2 strain HG52 was non-pathogenic to rabbit eyes and non-neuropathogenic. It had a very low frequency of spontaneous and induced shedding. The HSV-2 strain HG5 2 was able to maintain latent infections within the trigeminal ganglion. Twelve corneas from patients suffering from herpes simplex keratitis were collected and analysed by light microscopy, electron microscopy and organ culture. Two of the twelve corneas released HSV after at least seven days in organ culture. The released virus was identified as HSV-1 by restriction endonuclease analysis. Primary cultures of rabbit corneal epithelial cells, keratocytes and endothelial cells were established. The identity of the cells was confirmed by electron microscopy and indirect immunofluorescence techniques. The one step growth kinetics of HSV-1 in the three distinct cell types were established. Latent infections were established in the distinct cell lines in vitro using supra optimal temperatures. Cellular stress proteins were demonstrated at supraoptimal temperatures. The antiviral agent acycloguanosine was unable to eliminate latent HSV infections at the supraoptimal temperature (4