COMPUTERIZED NAVIGATION ASSISTANCE FOR DRIVERS

Computer-assisted navigation systems provide navigation information to automobile drivers and are now available. They are capable of storing, processing and displaying information about street networks. The display typically mimics a printed street map. The underlying capabilities of these systems present unique opportunities for geographers to study spatial cognition, wayfinding, spatial search, the impact of spatial information on trip behavior, and market responses to potentially different travel patterns. Such systems are reviewed and key areas for future research are identified.     

Origin of Lower Cretaceous quartzose arenites in northern India and the Indus Basins of Pakistan—The result of provenance composition,weathering or diagenesis?

Lower Cretaceous (Aptian-Albian) sandstones of the Ghaggar-Hakra Formation in the Barmer Basin of northwest Rajasthan, India, have a complex depositional history which is confusing given they are quartzose arenites. The heavy mineral grains are very well-rounded, and the assemblage is dominated by zircon and rutile grains suggesting that the sediments have been recycled multiple times, whilst the presence of staurolite indicates a metapelite provenance component. Petrographical analysis suggests that extreme diagenesis cannot account for the quartzose arenite composition, despite Early Cretaceous soil formation and at least two periods of subsequent telogenetic modification. An alternative explanation to extreme chemical weathering in the provenance area is that the Ghaggar-Hakra sandstones are multi-cycle sediments derived, at least in part, from the quartzose arenites of the Cambrian Jodhpur Group. This analysis suggests that variations in detrital mineralogy across the Western India Rift System and Indus Basins are the result of transcontinental fluvial transport systems sourcing sediment from specific basement highs (Nagar Parker High, Devikot High, Deodar Ridge and Aravalli Mountain Range) mixed with varying proportions of sediment derived from sandstones of the Jodhpur Group. Consequently, we suggest that Cretaceous fluvial systems were controlled by the local palaeogeographies within the failed rifts of the Barmer and Cambay Basins and that both basins formed barriers to sediment transport from the Aravalli Mountain Range across the northwest Indian plate and into surrounding basins.     

Three-dimensional nonlinear analysis for seismic soil–pile-structure interaction

A three-dimensional method of analysis is presented for the seismic response of structures constructed on pile foundations. An analysis is formulated in the time domain and the effects of material nonlinearity of soil on the seismic response are investigated. A subsystem model consisting of a structure subsystem and a pile-foundation subsystem is used. Seismic response of the system is found using a successive-coupling incremental solution scheme. Both subsystems are assumed to be coupled at each time step. Material nonlinearity is accounted for by incorporating an advanced plasticity-based soil model, HiSS, in the finite element formulation. Both single piles and pile groups are considered and the effects of kinematic and inertial interaction on seismic response are investigated while considering harmonic and transient excitations. It is seen that nonlinearity significantly affects seismic response of pile foundations as well as that of structures. Effects of nonlinearity on response are dependent on the frequency of excitation with nonlinearity causing an increase in response at low frequencies of excitation.     

Multifrequency polarimetry of 300 radio pulsars

Polarimetric observations of 300 pulsars have been conducted with the 76-m Lovell telescope at Jodrell Bank at radio frequencies centred around 230, 400, 600, 920, 1400 and 1600 MHz. More than half of the pulsars have no previously published polarization profiles and this compilation represents about three times the sum of all previously published pulsar polarization data. A selection of integrated polarization profiles is provided. Tables of pulse widths and the degree of both linear and circular polarization are given for all pulsars, and these act as an index for all the data, which are available by anonymous ftp in numerical and graphical form.     

Ideology and data analysis in African population policies. The case of Kenya

It is argued that the research agenda on fertility decline needs to be explanatory rather than operational and not tied to government policy justification. The research agenda should be set in the broader developmental and geographic contexts and with consideration of cultural practices. Demographic and Health Surveys provide limited biosocial data, which does not provide a fuller analysis of the factors affecting contraceptive use and effectiveness. Clear associations are drawn between rising contraceptive use and fertility decline and are used as supports for national and international policy makers. Although policy formation may be justified by this research agenda, the view is taken that this is "bad science." Kenya has been used as a model for population change in Africa. Kenya is viewed as a country with obvious direct government involvement in policies on fertility reduction, which mirror the ideological biases of the global model. The global model assumes a universal relationship between fertility and contraceptive prevalence and attaches little significance to cultural differences. However, research recognizes that in Africa family relationships, land tenure, and economic organization are different and highly variable. If economic and social variables on Kenya were available, it is possible that the economic change hypothesis could be proven. Kenya has great regional differences and wide gaps in levels of development. For many countries population growth is the key factor in development, and policies reflect the threat of loan conditions or reductions in foreign aid. Many African countries moved in the direction of reducing population growth through improved health and education, more jobs, improved status of women, and other indirect measures. This approach relies on the Western model of demographic transition. This author argues that knowledge and conclusions about fertility in Africa are more conditioned by ideology rather than technical concerns. In the case of Kenya ideology is supported by research, but a fuller explanation of family formation is not yet available. Kenya's population policy is based on the contraception hypothesis, and data are not yet available for testing other alternative child mortality or economic change hypotheses and constructively informing policy makers about fertility decline.     

Tracing Chernobyl's Fallout

When the third angel blew his trumpet a great star flaming like a torch descended from the sky, falling upon the third part of the rivers and upon the sources of water. The star is called wormwood. The third part of the waters turned to wormwood, and great numbers of men died from drinking the waters because they had been poisoned.     

Characterizing microlensing planetary system OGLE-2014-BLG-0676Lb with adaptive optics imaging

We constrain the host-star flux of the microlensing planet OGLE-2014-BLG-0676Lb using adaptive optics(AO)images taken by the Magellan and Keck telescopes.We mea...     

A fertility transition in Sub-Saharan Africa?

This paper documents and summarizes data on the recent fertility decline in sub-Saharan Africa and reviews the critical theoretical, methodological, and policy issues and controversies that the African situation provokes. After an introduction, African fertility change for the period 1960-94 is described through a discussion of fertility trends and of the proximate determinants of the fertility change. This discussion is illustrated with tables on the total fertility rate for countries of sub-Saharan Africa for the periods 1975-85 and 1986-93, and total fertility rates for countries participating in the Demographic and Health Surveys (DHS) for the periods 0-3 and 4-7 years prior to the survey. Figures show maps of Africa displaying total fertility rates in sub-Saharan Africa for 1975-85 and 1986- 93, and graphs of absolute and percentage change in total fertility rates for DHS countries between periods 0-3 and 4-7 years prior to the survey. The next section deals with theoretical issues such as whether the classic model of demographic transition is applicable to Africa and Jack Caldwell's views that cultural values make Africa different. It is seen that existing theory is of limited value in explaining the recent fertility decline in the region and that the two theories are beginning to converge to some degree. Consideration of methodological issues centers on the limited usefulness of fertility data collected by the large-scale, standardized demographic surveys to aid in the identification of patterns and processes. The discussion of policy issues is concerned with how survey data have been used and interpreted to formulate policy. The paper closes by reviewing the east Asian, South African, and Caribbean models of fertility decline and discussing problems in predicting the nature and extent of future fertility change in sub-Saharan Africa in light of recent findings.