Distributions and seasonal variability of dissolved organic nitrogen in two estuaries in SW England

Nitrogen loadings to coastal waters have increased over the last century, resulting in deterioration in water quality. In this study we investigated the distributions and seasonality of dissolved organic nitrogen (DON), and its relationship to total dissolved nitrogen (TDN), for two anthropogenically influenced estuarine systems in southwest England. Concentrations of DON in both estuaries were generally < 80 μM. DON showed non-conservative distributions, resulting from external and internal inputs and in situ reactivity. DON contributed 38 ± 22% (range 4–79%, Yealm) and 36 ± 17% (range 4–84%, Plym) to the TDN pool, with lower values generally observed in the fresher samples relative to the more saline samples. DON was a larger fraction of the TDN pool during the summer and autumn relative to winter and spring, indicating the influence of bacterioplankton release on nitrogen cycling in the estuaries. Ammonification and nitrification were observed in the estuaries, processes which were reproduced in incubation experiments using bioreactors. The bioreactor experiments showed that 12% h^− 1 of the DON flux from the River Plym may be available to bacteria, indicating significant removal of DON during the residence time of the water in the estuary (a few days). The bioavailable nature of the DON means that this N fraction significantly adds to the eutrophication burden of the receiving coastal waters, and therefore cannot be ignored in environmental assessments.     

Geomechanical evaluation of Pliocene natural aggregates as pavement materials

Asphaltic roads and constructions in Egypt annually consume a huge amount of aggregates. The physical and geomechanical properties of these aggregates have controlled their performance in which they are used. All road pavements require the efficient use of locally available materials if economically constructed roads are to be built. More than 650 million m³ of fine and coarse aggregates are herein selected to be the tonnage of the present study. The studied Pliocene aggregates have smoothed grading curves and neither a deficiency nor excess of any one particle size, generally produce good mixtures with fewer voids between particles. The litho-particles of coarse aggregates are composed mainly of granites, gneisses, granodiorite, gabbro, and quartz particles. The sand equivalent value of fine aggregates varies from 95 to 97 %. The specific gravity values of the studied aggregates vary from 2.72 to 2.74 gm/cm³ for coarse aggregate and range from 2.51 to 2.54 gm/cm³ for fine aggregate. The Los Angles abrasion value varies from 19 to 24 %. Both coarse and fine aggregates meet the international standards which are suitable for usage as subbase and surface course aggregates, respectively.     

Motion of artificial satellites in the set of Eulerian redundant parameters,II

In this paper the full recurrent power series solution is established for J ₂-gravity perturbed motion in terms of the Eulerian redundant parameters. Applications of the method for the problem of the final state prediction are illustrated by numerical examples of some typical ballistic missiles, a final state of very high accuracy is obtained for each case study.     

Assessing the engineering properties of concrete made with fine dune sands: an experimental study

Sand dunes cover an area of 16.6% of the total area of Egypt. This paper presents the results of an extensive laboratory testing that was carried out to determine the engineering properties of concrete. The concrete fine aggregate is fine dune sands obtained from three sites in the Kharga Oasis, Western Desert, Egypt. All samples were classified as poorly graded sand according to the Unified Soil Classification system. Fineness modulus values of the studied dune sands range from 0.89 to 0.97. The percentage of sulfates and chlorides are very low and nearly negligible. Sodium and calcium hydroxides were recorded in some samples with scarce concentration. Organic impurities were not recorded. The degree of workability of the studied dune sands ranged from low to medium, which are suitable for normal reinforced work without vibration and heavily reinforced section with vibration. The measured compressive strength of concrete decreases with increasing dune sand content.     

地理信息共享行为模型及其实证研究

地理信息共享不仅是地球系统科学发展的必然要求,而且对推动科学数据共享具有重要意义。自地理信息共享的概念提出以来,对地理信息共享的研究主要集中在地理信息共享技术上,但地理信息共享的实践证明,并非所有地理信息共享的障碍都能通过技术方法来解决,因此需要从非技术视角对地理信息共享进行研究。本文从新的视角,即行为的视角对地理信息共享进行了研究。本文介绍了地理信息共享行为模型,在对我国同地理信息共享有关的主要部门的问卷调查的基础上,通过实证研究,定量地分析了影响我国地理信息共享的非技术因素。结合Omran在埃及和荷兰的实证研究结果,分析了文化差异对地理信息共享行为的影响。在定性和定量分析的基础上,检验和修正了地理信息共享行为模型,并以此为基础,为我国的地理信息共享环境建设提出了相关的建议。实证研究的结果也表明,地理信息共享行为模型在不同的文化背景下的适用性。     

Characteristic of groundwater potentialities in West Nile Valley South,Minia Governorate,Egypt

The main aim of the present study is to detect the status of groundwater resources in west Mallawi area which represented one of the new reclamation lands. In order to achieve this aim, the hydrogeological and hydrogeochemical studies are carried out, based on the results of 21 pumping tests and chemical analysis of 29 water samples. Two water-bearing units are detected in the study area, namely, the Eocene fractured limestone aquifer which occupies the east portion of the studied area. The second aquifer consists of friable sediments of sand and gravel and may be related to the late Oligocene–early Miocene age and overlies the limestone rocks in the west, and this aquifer were studied for the first time in this work. Regionally, the groundwater flow in the area under study occurs toward the north and east directions. There is a hydraulic connection between both aquifers through the structural pattern affected the area. The partial recharge of the both aquifers takes place through the upward leakage from deep aquifers and the Nile water. There is a general decrease in the water salinity from west to east direction. The groundwater of both aquifers was evaluated for the different purposes and concluded that, it is considered suitable for different uses.     

Study of the Earth's oblateness and rotating atmosphere effects upon an artificial satellite in terms of KS-regular variables

This paper is concerned with an orbit prediction with the KS-regular variables. Perturbations due to the gravitational oblateness of the Earth, and the rotating atmosphere are considered. Application of the method for the perturbed motion are illustrated by numerical and graphical examples for a test case of the orbit.     

Quantitative indices for medical & personnel facilities

The status of medical facilities and personnel in the Kingdom of Saudi Arabia, at the end of the fourth five-year plan (1985–1990) was reviewed and analyzed regarding the standards of services and workload of health personnel for the different regions and urban/rural areas in the Kingdom. Innovative indices for the quantitative analysis of medical facilities were developed. The analysis of health facilities in Saudi Arabia shows that the Kingdom enjoys a high standard of medical facilities. However, there are maldistribution of clinical resources and personnel between regions and between urban/rural areas. Utilization of these indices for the reallocation of medical facilities and personnel to ensure even distribution of services for all inhabitants of the Kingdom was illustrated. In addition, indices give a guideline for the future planning and the rate of increase of these facilities that keeps the standard of medical services in the proper class desired with minimum resources wastage.