Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

A widely hypothesized but complex transition from widespread fluvial activity to predominantly aeolian processes is inferred on Mars based on remote sensing data observations of ancient landforms. However, the lack of analysis of in situ martian fluvial deposits hinders our understanding of the flow regime nature and sustainability of the martian fluvial activity and the hunt for ancient life. Studying analogs from arid zones on Earth is fundamental to quantitatively understanding geomorphic processes and climate drivers that might have dominated during early Mars. Here we investigate the formation and preservation of fluvial depositional systems in the eastern Sahara, where the largest arid region on Earth hosts important repositories of past climatic changes. The fluvial systems are composed of well-preserved single-thread sinuous to branching ridges and fan-shaped deposits interpreted as deltas. The systems' configuration and sedimentary content suggest that ephemeral rivers carved these landforms by sequential intermittent episodes of erosion and deposition active for 10-100s years over ∼10,000 years during the late Quaternary. Subsequently, these landforms were sculpted by a marginal role of rainfall and aeolian processes with minimum erosion rates of 1.1 ± 0.2 mm/yr, supplying ∼96 ± 24 × 10¹⁰ m³ of disaggregated sediment to adjacent aeolian dunes. Our results imply that similar martian fluvial systems preserving single-thread, short distance source-to-sink courses may have formed due to transient drainage networks active over short durations. Altogether, this study adds to the growing recognition of the complexity of interpreting climate history from orbital images of landforms.

Translation and validation of an Arabic version of the UK oral health related quality of life measure (OHQoL-UK) in Syria, Egypt and Saudi Arabia

OBJECTIVE

The aim of this study was to translate and evaluate the performance of an oral health related quality of life measure--an Arabic version of OHQoL-UK in three middle eastern countries: Syria, Egypt and Saudi Arabia.

BASIC RESEARCH DESIGN

Following forward and backwards translation of OHQoL-UK into Arabic and pilot testing the Arabic version among focus groups, a questionnaire containing the instrument was administered to 1,000 adults from the three Arab countries. In addition, the study participants were interviewed about their oral health status, experience of oral health problems in the past year, self-rating of oral health and also some socio-demographic information was collected.

RESULTS

Among the three study populations, variations in OHQoL-UK scores were apparent in relation to socio-demographic factors (p<0.01), self-reported number of teeth possessed (p<0.001) and experience of oral health problems in the past year (p<0.01) which supports the construct validity of the instrument. Furthermore, variations in OHQoL-UK scores were apparent in relation to self-rating of oral health status (p<0.01) which supports the criterion validity of the measure. The internal reliability of the instrument was high in the three groups with Cronbach alpha values of above 0.90, indicating good internal consistency.

CONCLUSION

The Arabic version of OHQoL-UK, an index of oral health related quality of life demonstrated satisfactory construct validity, criterion validity and internal reliability in Syria, Egypt and Saudi Arabia. This provides further evidence of the instrument's psychometric properties and its cross cultural use.

Developing a DSS for a distribution facility: an application in the healthcare industry

This article details a successful project in the design and implementation of a decision support system for practical use in a hospital setting. The approach used, the steps followed, the problems encountered, and the lessons learned are described and discussed with special emphasis on the managerial issues and management involvement during the decision support system life cycle.