Radial solitons in armchair carbon nanotubes

Radial solitons are investigated in armchair carbon nanotubes using a generalized Lennard-Jones potential. The radial solitons are found in terms of moving kink defects whose velocity obeys a dispersion relation. Effects of lattice discreteness on the shape of kink defects are examined by estimating the Peierls stress. Results suggest that the typical size for an unpinned kink phase is of the order of a lattice spacing.Comment: 11 pages, 3(eps) figure

Coming NAFTA Crash: The Deadly Impact of a Secret NAFTA Tribunal's Decision to Open U.S. Highways to Unsafe Mexican Trucks

Report documents that Mexico's truck safety regulations are virtually non-existent, that Mexican trucks have far more safety deficiencies than U.S. trucks, that a disproportionate number of Mexican trucks crossing the border have been taken out of service for serious safety violations, and that the U.S. lacks enough inspectors to check incoming trucks. Further, Texas border communities within the commercial border zone in which Mexican trucks are permitted have seen a dramatic increase in highway fatalities and serious injuries from crashes involving trucks with Mexican registrations, the report found

Interpreting the management of information systems security

The management of adverse events within organisations has become a pressing issue as the perceptions of risk continue to heighten. However the basic need for developing secure information systems has remained unfulfilled. This is because the focus has been on the means of delivery of information, i.e. the technology, rather than on the various contextual factors related to information processing. The overall aim of this research is to increase understanding of the issues and concerns in the management of information systems security. The study is conducted by reviewing the analysis, design and management of computer based information in two large organisations - A British national Health Service Hospital Trust and a Borough Council. The research methodology adopts an interpretive mode of inquiry. The management of information systems security is evaluated in terms of the business environment, organisational culture, expectations and obligations of different roles, meanings of different actions and the related patterns of behaviour. Findings from the two case studies show that an inappropriate analysis, design and management of computer based information systems affects the integrity and wholeness of an organisation. As a result, the probability of occurrence of adverse events increases. In such an environment there is a strong likelihood that security measures may either be ignored or are inappropriate to the real needs of an organisation. Therefore what is needed is coherence between the computer based information systems and the business environment in which they are embedded. In conclusion, this study shows that to resolve the problem of managing information systems security, we need to understand the deep seated pragmatic aspects of an organisation. Solutions to the problem of security can be provided by interpreting the behavioural patterns of the people involved

Imaging correlates of molecular signatures in oligodendrogliomas.

Molecular subsets of oligodendroglioma behave in biologically distinct ways. Their locations in the brain, rates of growth, and responses to therapy differ with their genotypes. Retrospectively, we inquired whether allelic loss of chromosomal arms 1p and 19q, an early molecular event and favorable prognostic marker in oligodendrogliomas, were reflected in their appearance on magnetic resonance imaging. Loss of 1p and 19q was associated with an indistinct border on T(1) images and mixed intensity signal on T(1) and T(2). Loss of 1p and 19q was also associated with paramagnetic susceptibility effect and with calcification, a common histopathological finding in oligodendrogliomas. These data encourage prospective evaluation of molecular alterations and magnetic resonance imaging characteristics of glial neoplasms

The unusual distribution of molecular gas and star formation in Arp 140

We investigate the atomic and molecular interstellar medium and star formation of NGC 275, the late-type spiral galaxy in Arp 140, which is interacting with NGC 274, an early-type system. The atomic gas (HI) observations reveal a tidal tail from NGC 275 which extends many optical radii beyond the interacting pair. The HI morphology implies a prograde encounter between the galaxy pair approximately 1.5 x 10**8 years ago. The Halpha emission from NGC 275 indicates clumpy irregular star-formation, clumpiness which is mirrored by the underlying mass distribution as traced by the Ks-band emission. The molecular gas distribution is striking in its anti-correlation with the {HII regions. Despite the evolved nature of NGC 275's interaction and its barred potential, neither the molecular gas nor the star formation are centrally concentrated. We suggest that this structure results from stochastic star formation leading to preferential consumption of the gas in certain regions of the galaxy. In contrast to the often assumed picture of interacting galaxies, NGC 275, which appears to be close to merger, does not display enhanced or centrally concentrated star formation. If the eventual merger is to lead to a significant burst of star formation it must be preceded by a significant conversion of atomic to molecular gas as at the current rate of star formation all the molecular gas will be exhausted by the time the merger is complete.Comment: 13 paper, accepted my Monthly Notices of the Royal Astronomical Societ

'Ibadan - a model of historical facts': militarism and civic culture in a Yoruba city

The article focuses on an historical relationship between the political institution of chieftaincy and civic pride in Ibadan, a Yoruba city in south-western Nigeria. It examines this relationship against the scholarly model of ‘Yoruba urbanism’ and argues that this model is empirically and conceptually flawed. Drawing on oral and documentary historical sources, the article explores how a ‘civic Ibadan’ was made through practices of settlement, civil disorder and external warfare during the pre-colonial period. The analysis adds to recent debates about the concept of ‘historical materialism’ in the urban past

A class of multipartner matching markets with a strong lattice structure

For a two-sided multipartner matching model where agents are given by path-independent choice functions and no quota restrictions, Blair [7] had shown that stable matchings always exist and form a lattice. However, the lattice operations were not simple and not distributive. Recently Alkan [3] showed that if one introduces quotas together with a monotonicity condition then the set of stable matchings is a distributive lattice under a natural definition of supremum and infimum for matchings. In this study we show that the quota restriction can be removed and replaced by a more general condition named cardinal monotonicity and all the structural properties derived in [3] still hold. In particular, although there are no exogenous quotas in the model there is endogenously a sort of quota; more precisely, each agent has the same number of partners in every stable matching. Stable matchings also have the polarity property (supremum with respect to one side is identical to infimum with respect to the other side) and a property we call complementarity

Book Review

Review of: MANAGEMENT OF HAZARDOUS AGENTS. Vol. 1: INDUSTRIAL AND REGULATORY APPROACHES. Vol. 2: SOCIAL, POLITICAL, AND POLICY ASPECTS. (Duane G. LeVine & Arthur C. Upton eds., Praeger 1992). Each volume contains: bibliography, series foreword, foreword, figures, notes, biographical references, tables, index. Vol. 1: [194 pp.] LC-92-167 ISBN 0-275-94322-4. Vol. 2: [188 pp.] ISBN 0-275-94323-2. [Cloth, each $49.95. 88 Post Road West; Westport CT 06881.

Defining Regional Boundaries

The purpose of this resource is to identify a reqion for study as a system, and to establish a list of characteristics and features useful for determining the boundaries of regional systems. Students discuss their current understanding of what Earth systems are and how they work, and consider how to identify the boundaries of a region for Earth system study. In small groups, they select a region for recommendation to the class, and they make a list of characteristics and features that can mark the boundaries of regional systems. After presentations by each group, the class chooses one region for study as an Earth system. Then they mark the boundaries of their chosen region on their Landsat image, topographic map, or other map. Educational levels: Middle school, High school

Differential trends in the compression of mortality: Assessing the antecedents to current gaps in health expectancy in New Zealand

Health Expectancies (HEs) for New Zealand show significant differentials between Maori and non-Maori, but also by gender and period. These differentials correlate with findings from both generation and synthetic life-tables relating to New Zealand’s epidemiologic transition. At the beginning of that transition quartile 1 (Q(1)), and Median (Med) d(x) values were close and centred at young ages; during the transition the gap became very wide; at the transition’s end the gap again narrowed. Cohort and synthetic trends in d(x), l(x), M, Qs and Meds are reviewed and linked to recent HEs. Data point to epidemic polarisation. Cohort analysis allows the evaluation of the role of past experiences on the recent HEs, and thus point to possible strategies for reducing gaps in both d(x), and HEs