Atlas: a nested relational database system for text applications

Advanced database applications require facilities such as text indexing, image storage, and the ability to store data with a complex structure. However, these facilities are not usually included in traditional database systems. In this paper we describe Atlas, a nested relational database system that has been designed for text-based applications. The Atlas query language is TQL, an SQL-like query language with text operators. The query language is supported by signature file text indexing techniques, and by a parser that can be configured for different text formats and even some foreign languages. Atlas can also be used to store images and audio     

The prevalence of psychiatric disorders at a primary care clinic in Soweto, Johannesburg

A pilot study to assess the prevalence of psychiatric disorders in a primary care clinic in Soweto was carried out at the Zola Community Health Centre in May 1991. Interviews were carried out by trained primary care clinic staff. The findings were reviewed and analysed by the authors. The prevalence of psychiatric disorders was found to be 14.38%. Methodological problems are listed and the results are discussed.     

Left ventricular hypertrophy, blood pressure and ACE genotype in untreated hypertension

It has been suggested that the deletion polymorphism of the angiotensin-converting enzyme (ACE) genotype may be important in the development of left ventricular hypertrophy (LVH). In order to test this hypothesis we investigated the interaction between blood pressure (BP), LVH and ACE genotype in 86 previously untreated hypertensive patients. Each underwent two-dimensional and Doppler echocardiography and ACE genotyping. There were no significant differences in BP, the parameters of left ventricular structure (including left ventricular mass index) or diastolic function between the three genotype groups. Additionally, there were no significant differences in the relationship between systolic BP and left ventricular mass index among the three genotype groups (II genotype, r = 0.46, P = 0.02; ID genotype, r = 0.42, P = 0.01; DD genotype, r = 0.34, P = 0.10; F = 0.38). In contrast to some previous studies, we have found in this group of previously untreated hypertensive subjects no evidence to suggest that the deletion polymorphism of the ACE genotype is important in the development of LVH.     

Transport of chemical vapors through soil: A landfill cover simulation experiment

Experimental simulation studies of the transport of volatile organic chemical vapors by both diffusion and convection through soil covers, as in landfi     

Modeling the Accumulation of Degradable Polymer Drug Carriers in the Brain

The blood–brain barrier (BBB) limits the access of drugs to the brain. Intensive research is being conducted on the development of nanoparticulate drug carriers that mediate transfer across the BBB. A question that has been neglected so far is the potential accumulation of the carrier in the brain upon long‐term exposure. Here, we address this question by implementing a kinetic model to relate drug loading, required concentration of drug in the brain, and drug clearance to the degradation half‐life of the carrier. As a test case with clinical relevance we chose poly‐lactic‐co‐glycolic‐acid (PLGA) as a carrier material and a chemotherapeutic for which the required parameters could be recovered from the literature. For methotrexate with a drug load of 8.5 %, a required concentration of free drug of 1 μm , a release from PLGA of 6 hours, a drug clearance from the brain of 3 hours and a half‐life of polymer degradation of 28 days, a steady‐state accumulation of 1.3 g polymer would be reached in the brain (1.5 L) after seven months. While this number is surprisingly small, further physiological research is warranted to assess to which degree this will be in a tolerable range.     

Bird's‐Eye ‐ Large‐Scale Visual Analytics of City Dynamics using Social Location Data

The analysis of behavioral city dynamics, such as temporal patterns of visited places and citizens' mobility routines, is an essential task for urban and transportation planning. Social media applications such as Foursquare and Twitter provide access to large‐scale and up‐to‐date dynamic movement data that not only help to understand the social life and pulse of a city but also to maintain and improve urban infrastructure. However, the fast growth rate of this data poses challenges for conventional methods to provide up‐to‐date, flexible analysis. Therefore, planning authorities barely consider it. We present a system and design study to leverage social media data that assist urban and transportation planners to achieve better monitoring and analysis of city dynamics such as visited places and mobility patterns in large metropolitan areas. We conducted a goal‐and‐task analysis with urban planning experts. To address these goals, we designed a system with a scalable data monitoring back‐end and an interactive visual analytics interface. The monitoring component uses intelligent pre‐aggregation to allow dynamic queries in near real‐time. The visual analytics interface leverages unsupervised learning to reveal clusters, routines, and unusual behavior in massive data, allowing to understand patterns in time and space. We evaluated our approach based on a qualitative user study with urban planning experts which demonstrates that intuitive integration of advanced analytical tools with visual interfaces is pivotal in making behavioral city dynamics accessible to practitioners. Our interviews also revealed areas for future research.     

Mix design considerations of foamed bitumen mixtures with reclaimed asphalt pavement material

In the present work, a mix design parametric study was carried out with the aim of proposing a practical and consistent mix design procedure for foamed bitumen mixtures (FBMs). The mix design parameters that were adopted in the study are mixing and compaction water content (MWC), compaction effort using a gyratory compactor and aggregate temperature. This parametric study was initially carried out on FBMs with virgin limestone aggregate without reclaimed asphalt pavement (RAP) material and a mix design procedure was proposed. This proposed methodology was also found to apply to FBMs with RAP. A detailed consideration was also given to characterising the RAP material so as to understand its contribution to the mechanical properties of FBMs. Optimum MWC was achieved by optimising mechanical properties such as indirect tensile stiffness modulus and indirect tensile strength (ITS-dry and ITS-wet). A rational range of 75–85% of optimum water content obtained by the modified Proctor test was found to be the optimum range of MWC that gives optimum mechanical properties for FBMs. It was also found that the presence of RAP influenced the design foamed bitumen content, which means that treating RAP as black rock in FBM mix design is not appropriate. To study the influence of bitumen and water during compaction, modified Proctor compaction and gyratory compaction were employed on mixes with varying amounts of water and bitumen. By this, the work also evaluated the validity of the total fluid (water + bitumen) concept that is widely used in bitumen–emulsion-treated mixes, and found it not to be applicable.     

A field evaluation of driver eye and head movement strategies toward environmental targets and distractors

A new systems approach for evaluating field performance of drivers is presented in a practical experimental demonstration. The emphasis reflected in this paper is on driver head and eye movement behaviour toward environmental targets and distractors. A unique video technology set-up was designed to record eye and head movements. Simultaneous video-tapings of driver eye/head movements and the environmental scene were time synchronised. Two intersections (one busy and one quiet) were carefully selected and analysed for their static and dynamic visual targets and distractors. A subject made 40 repetitive left-turns alternately at busy and quiet intersections in a naturally moving traffic environment. Both head movement patterns and eye movement frequencies differed significantly between the two intersections. Results suggest that the eye and head movements are highly dependent upon the type of turn configuration, type and frequency of targets, type and frequency of distractors, and traffic control configurations.     

Improvement to method of equivalent thicknesses (MET) for calculation of critical strains for flexible pavements

This paper presents the results of a sensitivity analysis carried out to compare the values of asphalt and subgrade strains (as well as associated fatigue and deformation lives) obtained with the method of equivalent thicknesses (MET) with those calculated with the BISAR software. The strains were calculated for a large number of 3-layer flexible pavement structures. A linear regression analysis has been performed to predict the values of strain (as well as life) calculated with BISAR from those obtained with the MET methodology and with a desired level of confidence. The analysis showed that, while subgrade strains were predicted acceptably well, differences greater than ±10% exist between the two methods in the case of the asphalt strains. An alternative model is therefore proposed to improve the MET methodology results for 3-layer pavement structures. The alternative model provides a simple and efficient method for practical purposes, for example in Pavement Management Systems or in simulation of pavement deterioration, where stresses and strains must be calculated large numbers of times.