The Specification in Z of the REX Protocol

REX is a protocol supporting a client/server style of interaction between a number of entities in a distributed system. Within this interaction paradigm, client entities may request services supplied by server entities, by interacting with intermediate protocol entities. This paper presents a Z specification of part of the REX protocol

Quiescent consistency: Defining and verifying relaxed linearizability

Concurrent data structures like stacks, sets or queues need to be highly optimized to provide large degrees of parallelism with reduced contention. Linearizability, a key consistency condition for concurrent objects, sometimes limits the potential for optimization. Hence algorithm designers have started to build concurrent data structures that are not linearizable but only satisfy relaxed consistency requirements. In this paper, we study quiescent consistency as proposed by Shavit and Herlihy, which is one such relaxed condition. More precisely, we give the first formal definition of quiescent consistency, investigate its relationship with linearizability, and provide a proof technique for it based on (coupled) simulations. We demonstrate our proof technique by verifying quiescent consistency of a (non-linearizable) FIFO queue built using a diffraction tree. © 2014 Springer International Publishing Switzerland

IMPACTS ON PROPERTY TAXES OF RECLASSIFYING FLOOD-PRONE CROPLAND IN THE SOUTH DELTA AREA OF MISSISSIPPI

Current tax appraisal procedures for cropland in Mississippi do not account for any negative impacts caused by frequent flooding in some areas of the South Delta. If flood-prone cropland values are significantly below average, the current tax system could generate inequitable tax burdens on owners of flood-prone cropland. A modified system of appraisal may be desirable to produce a more equitable tax structure. The purpose of this study was to evaluate different methods of reclassifying flood-prone cropland in the South Delta and to determine subsequent tax impacts on landowners and county tax revenue. Cropland tax data for Sharkey and Issaquena Counties were collected and different permanent reclassification schemes were proposed. Reclassification schemes were defined by lowering a parcel's capability class assignment by 1, 2, 3, or 4 classes if its elevation was below a specified trigger level. The impact that each reclassification scheme would have on landowners' taxes and the tax base in the affected counties was then estimated. In order to show the impact on tax shifts that would keep the county's tax base from declining, a new, higher millage rate was computed for selected reclassification schemes. After applying the adjusted millage rate to all properties in the county, changes in cropland taxes were reduced. Among the permanent reclassification schemes evaluated in this study, a trigger elevation level of 90 feet appears to offer reasonable tax impacts. Cropland parcels below 90 feet could be reassigned to the lowest capability class if the residents desired to provide the largest tax relief to these property owners. A more conservative reassignment scheme could be selected if desired. A temporary (year-to-year) reclassification system may provide more equitable tax distributions over time but would probably require more administrative costs to implement.Cropland appraisal, property taxes, flood-prone cropland, Land Economics/Use,

Multiparton Interactions in Photoproduction at HERA

The high energy photoproduction of jets is being observed at the ep collider, HERA. It may be that the HERA centre-of-mass energy is sufficiently large that the production of more than one pair of jets per ep collision becomes possible, owing to the large number density of the probed gluons. We construct a Monte Carlo model of such multiparton interactions and study their effects on a wide range of physical observables. The conclusion is that multiple interactions could have very significant effects upon the photoproduction final state and that this would for example make extractions of the gluon density in the photon rather difficult. Total rates for the production of many (i.e. > 2) jets could provide direct evidence for the presence of multiple interactions, although parton showering and hadronization significantly affect low transverse energy jets.Comment: 21 pages, 8 figures include

The Trypanosoma brucei AIR9-like protein is cytoskeleton-associated and is required for nucleus positioning and accurate cleavage furrow placement

AIR9 is a cytoskeleton-associated protein in Arabidopsis thaliana with roles in cytokinesis and cross wall maturation, and reported homologues in land plants and excavate protists, including trypanosomatids. We show that the Trypanosoma brucei AIR9-like protein, TbAIR9, is also cytoskeleton-associated and colocalises with the subpellicular microtubules. We find it to be expressed in all life cycle stages and show that it is essential for normal proliferation of trypanosomes in vitro. Depletion of TbAIR9 from procyclic trypanosomes resulted in increased cell length due to increased microtubule extension at the cell posterior. Additionally, the nucleus was re-positioned to a location posterior to the kinetoplast, leading to defects in cytokinesis and the generation of aberrant progeny. In contrast, in bloodstream trypanosomes, depletion of TbAIR9 had little effect on nucleus positioning, but resulted in aberrant cleavage furrow placement and the generation of non-equivalent daughter cells following cytokinesis. Our data provide insight into the control of nucleus positioning in this important pathogen and emphasise differences in the cytoskeleton and cell cycle control between two life cycle stages of the T. brucei parasite

Basal body movements as a mechanism for mitochondrial genome segregation in the trypanosome cell cycle

International audienc

MUSCULOSKELETAL LOADING AND IMPLICATIONS FOR INJURY

There are numerous variables used to assess musculoskeletal loading during human movement. This presentation will examine ground reaction forces, segment accelerations, joint contact forces and internal bone stresses and strains. I will cover implications for injury assessment, subtleties of interpretation, benefits and drawbacks of each these methods

An Analysis into the Effectiveness of Aircraft Maintenance under the Combat Wing Structure

Organizational structure builds the foundation from which organizations operate. To gain full potential of structural efficiencies in the current operating environment, public and private firms are continually modifying their organizational structure. The U.S. Air Force is no different and underwent its most recent reorganization in the fall of 2002 replacing the post-Gulf War format of the previous decade. Air Force leadership needs to understand how well the current structure is performing at achieving its intended objectives. This research investigates the effectiveness of the recent change to Air Force organizational structure on aircraft maintenance performance through an analysis of aircraft maintenance metrics. To observe effects both within and across the Air Force, four years of data were analyzed from three F-16 units and three KC-135 units representing two of the significant Air Force Major Commands. The analytical methods used for this research include testing assumptions of normality and variance of sample data, homogeneity of variance and comparison of means, weighted factoring, and trend analysis using linear regression to determine the overall effectiveness of the combat wing structure. Results of this analysis allowed the researcher to postulate an answer to the overall research question. This answer and other associated findings can assist Air Force leaders in understanding how to enhance operational performance

Konstruiranje vidljivosti: fotografija Esther Born izvan arhiva

Esther Baum Born was an American photographer who worked in both the United States and Mexico. Beginning in the 1920s, she exhibited her work regularly in New York galleries and saw her photographs published in a broad spectrum of architectural journals. Born’s book, The New Architecture in Mexico (1937), stands as an undisputed monument to her creative insights and a respected source for cutting-edge ideas about modern building. Less well known to the scholarly community are the sensitive portraits that Born took of her own artistic milieu: Frida Kahlo, Diego Rivera, and Frank Lloyd Wright, to name only a few, appeared before her camera. The author argues that these images represent an area for future research. In any event, Born’s creative flourishing was largely eclipsed once she joined the highly successful architectural practice of her husband, Ernest Born. She gave up photography entirely in the 1940s to support his work. The legacy of both Borns remains fairly well-known to students of Bay Area architecture, who have admired their contributions to public transportation (designing train stations), urban renewal (developing master planning documents), and book design (such as the Plan of St. Gall, co-authored with art historian, Walter Horn). Much of the couple’s joint career is documented in established archives throughout the United States and Canada, although it needs to be said that Ernest Born is typically given top billing for the work. Esther Born’s early efforts as a photographer sit in these archives, too. A full assessment of her legacy as a photographer waits to be written. This paper attempts to give greater visibility to her ambitions as well as to the lasting consequence of her work’s placement within the many archival situations where it can be found today.Esther Baum Born bila je američka fotografkinja koja je radila u Sjedinjenim Državama i Meksiku. Počevši od 1920-ih, redovito je izlagala svoje radove u njujorškim galerijama i objavljivala fotografije u širokom spektru arhitektonskih časopisa. Njezina knjiga The New Architecture in Mexico [Nova arhitektura u Meksiku] (1937.) stoji kao neosporan spomenik njezinim kreativnim uvidima i predstavlja vrijedan izvor najsuvremenijih ideja o modernoj gradnji. Ono što je znanstvenoj zajednici manje poznato jesu tankoćutni portreti koje je Born snimala u vlastitom umjetničkom miljeu: pred njezinim fotoaparatom pojavljivali su se Frida Kahlo, Diego Rivera i Frank Lloyd Wright, da spomenemo samo neke. Autor smatra da te fotografije predstavljaju građu za buduća istraživanja. U svakom slučaju, kreativni procvat Esther Born uvelike je zasjenjen nakon što se pridružila vrlo uspješnoj arhitektonskoj praksi svoga supruga Ernesta Borna. Kako bi podržala njegov rad, 1940-tih se potpuno odrekla fotografije. Nasljeđe oboje Bornovih još je uvijek prilično dobro poznato studentima arhitekture područja Bay Area, koji se mogu diviti njihovom doprinosu javnom prijevozu (projektiranje željezničkih postaja), urbanoj obnovi (razvoj glavnih planskih dokumenata) i dizajnu knjiga (kao što je Plan of St. Gall [Plan St. Gallena], nastao u koautorstvu s povjesničarem umjetnosti Walterom Hornom). Velik dio zajedničke karijere bračnog para Born dokumentiran je u zasnovanim arhivima diljem Sjedinjenih Država i Kanade, iako treba reći da se najveće zasluge za taj rad obično pripisuju Ernestu Bornu. Rani radovi Esther Born iz područja fotografije također se nalaze u tim arhivima, ali na punu procjenu njezine ostavštine kao fotografkinje tek se čeka. Ovaj rad predstavlja pokušaj povećanja vidljivosti njezinih ambicija kao i dugotrajnih posljedica pozicioniranja njezinoga rada u mnogim arhivima u kojima se danas nalazi