The natural history of bugs: using formal methods to analyse software related failures in space missions

Space missions force engineers to make complex trade-offs between many different constraints including cost, mass, power, functionality and reliability. These constraints create a continual need to innovate. Many advances rely upon software, for instance to control and monitor the next generation ‘electron cyclotron resonance’ ion-drives for deep space missions.Programmers face numerous challenges. It is extremely difficult to conduct valid ground-based tests for the code used in space missions. Abstract models and simulations of satellites can be misleading. These issues are compounded by the use of ‘band-aid’ software to fix design mistakes and compromises in other aspects of space systems engineering. Programmers must often re-code missions in flight. This introduces considerable risks. It should, therefore, not be a surprise that so many space missions fail to achieve their objectives. The costs of failure are considerable. Small launch vehicles, such as the U.S. Pegasus system, cost around $18 million. Payloads range from$4 million up to $1 billion for security related satellites. These costs do not include consequent business losses. In 2005, Intelsat wrote off$73 million from the failure of a single uninsured satellite. It is clearly important that we learn as much as possible from those failures that do occur. The following pages examine the roles that formal methods might play in the analysis of software failures in space missions

Leisure time in eighteenth-century Virginia

Eighteenth-century Virginia was strikingly agrarian. Tobacco planting on the plantations and farms created an ever-increasing need for new land. The growth of a dispersed rural society reacted against the formation of urban focal units and a middle class. This society did create, because of the endemic loneliness of the country, a people who desired companionship and proved to be gregarious and convivial. The hospitality for which Virginians are well known was very much in evidence at this period and served in a subtle way to offer diversion to both guest and host. Travelers were invited to the plantations and farms at day or night during all seasons ot the year and experienced warm receptions. Leisure time activities evolved from or were closely related to the agricultural environment of the people. The salubrious climate and the demanding tasks of farming created a robust people who not only worked hard, but who played hard also. The horse to the Virginian was not only a tool of work, but a means of pleasure and recreation. Hunting for game provided meat and provisions for the planter\u27s table and necessary relaxation after an arduous day\u27s work. The Virginian\u27s great pride in horses led him, quite naturally, to challenge others to horse races, with money or tobacco as the victor\u27s reward. Cultural and recreational activities were inextricably mixed in the Old Dominion. There seems to have been little social activity relating to the churches and religious organizations. Most Virginians found their diversions in their homes among their families; others sought entertain­ ment at public events. Music and dancing appealed to almost all of the people, while a lesser number found reading and the theater rewarding recreational pastimes. The competitive spirit of Virginians ran the gamut of all their activities. They enjoyed varied games among which were billiards, cards, cockfights and bowls. Sports and related amusements were accompanied by considerable gambling in homes, taverns and throughout the country. Drinking was evident at almost every occasion, public and private, for the Virginian\u27s love of the rum toddy and other strong drinks was universally known. The annals of the lower classes are poor and few, but the writer desires to show that their forms of leisure were remarkably similar to those of the gentry. The lesser planters and the poorer farmers were also known for their sociability and hospitality. They shared in the gentry\u27s love of hunting and horse racing, of music and dancing and other pastimes. The writer also desires to show that the Negro affected some forms of diversion enjoyed by the planters and even contributed some forms of his own making which the master\u27s family found entertaining. Diaries of great men suoh as George Washington and William Byrd II offer a keen and perceptive insight as to the manner in which the wealthy planters lived and passed their leisure hours. These diaries also depict the manner of life and leisure time of the people with whom the planters associated whatever their station in life. Accounts written by travelers to Virginia offer revealing and informative descriptions of Virginians, the nature of their activities, their social structure, and how they appeared in their everyday lives to a stranger

Parents\u27 Perceptions of Smartphone Use and Parenting Practices

The present study is a qualitative examination aiming to gain insight into parents’ perceptions of their smartphone use and the effects it may be having on their children as well as parenting practices. Participants (N=12) were smartphone using parents that consisted mostly of young college-educated females. Thematic analysis of individual interviews resulted in five primary themes: (1) Disengagement, (2) Concern for Future, (3) Change in Social Norms, (4) Boundaries, and (5) Cognitive Dissonance. These findings indicate significant effects parental smartphone use is having in the lives of study participants. These thematic findings call for additional research examining the impact parental and adult smartphone use is having in all aspects of the family including the parental subsystem of the family system

Memetic Theory, Trademarks & The Viral Meme Mark, 13 J. Marshall Rev. Intell. Prop. L. 96 (2013)

This Article proposes that memetic theory is a useful lens through which to view trademarks, particularly as there has been a rise in the number of applications for culturally-driven words and catchphrases in the United States Patent and Trademark Office. Memetic theory, or memetics, is a scientific field related to how units of information evolve and replicate. These units of information, called memes, undergo a process of natural selection comparable to that of genes. To survive as trademarks, memes must not only exist in the proper form, but they must also subsist in an environment where replication, variation, and selection exist in appropriate measure. Under current trademark jurisprudence, over-protection and over-enforcement of trademarks pose a threat to the natural selection environment. The recent phenomenon of trademark applications for culturally driven words and catchphrases is but one manifestation of the interaction between memetic theory and trademark law. Applying memetics to trademark law calls for a reassessment of current legal standards. This Article concludes by offering further insight into where to explore the intersection between this incipient science and trademark law

Sequence elements controlling expression of Barley stripe mosaic virus subgenomic RNAs in vivo.

Barley stripe mosaic virus (BSMV) contains three positive-sense, single-stranded genomic RNAs, designated alpha, beta, and gamma, that encode seven major proteins and one minor translational readthrough protein. Three proteins (alphaa, betaa, and gammaa) are translated directly from the genomic RNAs and the remaining proteins encoded on RNAbeta and RNAgamma are expressed via three subgenomic messenger RNAs (sgRNAs). sgRNAbeta1 directs synthesis of the triple gene block 1 (TGB1) protein. The TGB2 protein, the TGB2' minor translational readthrough protein, and the TGB3 protein are expressed from sgRNAbeta2, which is present in considerably lower abundance than sgRNAbeta1. A third sgRNA, sgRNAgamma, is required for expression of the gammab protein. We have used deletion analyses and site-specific mutations to define the boundaries of promoter regions that are critical for expression of the BSMV sgRNAs in infected protoplasts. The results reveal that the sgRNAbeta1 promoter encompasses positions -29 to -2 relative to its transcription start site and is adjacent to a cis-acting element required for RNAbeta replication that maps from -107 to -74 relative to the sgRNAbeta1 start site. The core sgRNAbeta2 promoter includes residues -32 to -17 relative to the sgRNAbeta2 transcriptional start site, although maximal activity requires an upstream hexanucleotide sequence residing from positions -64 to -59. The sgRNAgamma promoter maps from -21 to +2 relative to its transcription start site and therefore partially overlaps the gammaa gene. The sgRNAbeta1, beta2, and gamma promoters also differ substantially in sequence, but have similarities to the putative homologous promoters of other Hordeiviruses. These differences are postulated to affect competition for the viral polymerase, coordination of the temporal expression and abundance of the TGB proteins, and constitutive expression of the gammab protein

Molecular clouds and clumps in the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey

The Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS) of 13 CO (1-0) emission covers Galactic longitudes 18 deg < l < 55.7 deg and Galactic latitudes |b| <= 1 deg. Using the SEQUOIA array on the FCRAO 14m telescope, the GRS fully sampled the 13 CO Galactic emission (46 arcsec angular resolution on a 22 arcsec grid) and achieved a spectral resolution of 0.21 km/s. Because the GRS uses 13 CO, an optically thin tracer, rather than 12 CO, an optically thick tracer, the GRS allows a much better determination of column density and also a cleaner separation of velocity components along a line of sight. With this homogeneous, fully-sampled survey of 13 CO, emission, we have identified 829 molecular clouds and 6124 clumps throughout the inner Galaxy using the CLUMPFIND algorithm. Here we present details of the catalog and a preliminary analysis of the properties of the molecular clouds and their clumps. Moreover, we compare clouds inside and outside of the 5 kpc ring and find that clouds within the ring typically have warmer temperatures, higher column densities, larger areas, and more clumps compared to clouds located outside the ring. This is expected if these clouds are actively forming stars. This catalog provides a useful tool for the study of molecular clouds and their embedded young stellar objects.Comment: 29 pages. ApJ in pres

Electron tunneling time measured by photoluminescence excitation correlation spectroscopy

The tunneling time for electrons to escape from the lowest quasibound state in the quantum wells of GaAs/AlAs/GaAs/AlAs/GaAs double-barrier heterostructures with barriers between 16 and 62 Å has been measured at 80 K using photoluminescence excitation correlation spectroscopy. The decay time for samples with barrier thicknesses from 16 Å (≈12 ps) to 34 Å(≈800 ps) depends exponentially on barrier thickness, in good agreement with calculations of electron tunneling time derived from the energy width of the resonance. Electron and heavy hole carrier densities are observed to decay at the same rate, indicating a coupling between the two decay processes