ملخص: لكل علم مفهوم يحدد مصطلحاته، وبالتالي المفاهيم اللازمة للفلسفة السياسية. إذا لم يكن من الممكن تطوير مفاهيم دقيقة ودقيقة ، فإن رؤانا واكتشافاتنا التجريبية ستفشل دائما في أن تكون دقيقة ودقيقة. لا تزال هذه الخيارات تشمل الحد الرئيسي لتحليل المفاهيم وكذلك التحديات الأساسية التي تواجه المفاهيم ، أي المفاهيم في دراسة السياسة.

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This study had been performed in Sabratha area to assign some physical, chemical and biological characteristics for underground water and to find out its propriety for drinking. The study area was divided into ten locality: Dahman, Al- Khatatba, Aljabbar, Subratha center, Soug Al-Alalgah, Aldababshiah, Alnahdah, Tillil, Altunaibat, and Aggar. Forty eight samples of underground water has been collected in the study area. Five wells from each site were chosen except in Subratha center, where three wells were chosen. After performing the necessary analysis it became clear that the total dissolved salts concentration in 93.75% of the wells exceeded the allowable limit for drinking water, the highest was found to 4444.060 PPM in Tillil area, in addition to that, it was found that 81.25% of the wells, water, exceeded the allowable limits for sulpher concentration in drinking water. It was found that the concentration of the chloride (Cl ‾) exceeded the allowable limit for drinking water in 93.75 % of the wells, and the concentration of nitrite (NO2‾) exceeded the allowable limit in 8.3 % of the wells, while the concentration of nitrate ion ( NO3‾ ), in all wells were compatible with the Libyan and International specifications. The Calcium ion (Ca+2) exceeded the allowable limit in 87.5% of the wells. We can found also that, the concentration of magnesium element (Mg) exceeded the allowable limit in 79.1% of the wells. As for the sodium (Na+) concentration, it exceeded the allowable limit for drinking water in 95.8% of the wells, the highest was recorded in Sabratha center (7782 ppm). Some of the wells were polluted from the biological aspect, that was due to the contamination by sewage waters. In this study we found that, 39.58% of the well waters were polluted and not compatible to the international and Libyan standard specifications for drinking water, while we found that 60.41% of the wells were not polluted and were compatible with the standards. From the chemical aspect we found that, the most wells in the study area were not good for drinking, especially those located to the north, since they are near the sea and they merge with sea water . We also can notice that many of the wells were not good for drinking from the biological aspect, so we recommend to perform chemical and biological analysis before using the underground waters for domestic, agricultural and industrial objectives. Key words: Underground water, chemical pollution, biological pollution, Sabratha, Libya

Evapotranspiration calculation is an important matter due to agricultural reasons, but also for understanding water resources and runoff amount in a certain territory. Two CMIP5 multimodal projections (2011–2040 and 2041–2070) and land-cover pattern were used to analyse the seasonal and annual crop evapotranspiration trend in Turkey. The spatial distribution of crop evapotranspiration related to the initial season, mid-season, end season and cold season were computed through a geographical information system. The maximum crop evapotranspirations were found in the mid-season for present and future, with 1,072 and 1,241 mm respectively. For the future period, an increase in the spatial distribution of crop evapotranspiration was depicted in several places due to climate warming, mainly in the southern and southeastern areas of Turkey and on the Mediterranean coast. The minimum seasonal crop evapotranspirations fell to below 154 and 164 mm in the present and future respectively. The annual crop evapotranspiration increased from 1,675 to 1,944 mm from present to future and the significant values of absolute changes were identified in the western, eastern and southeastern regions of Turkey. The findings are useful for scientists in the climate, hydrology and agriculture fields, but also for management decisions.

ABSTRACT

Swirl stabilised combustion is one of the most widely used techniques for flame stabilisation in gas turbine combustors. Lean premixed combustion systems allow the reduction of NOx coupled with fair flame stability. The swirl mechanism produces an aerodynamic region known as central recirculation zone (CRZ) providing a low velocity region where the flame speed matches the flow velocity, thus anchoring the flame whilst serving to recycle heat and active chemical species to the root of the f

ormer. Another beneficial feature of the CRZ is the enhancement of the mixing in and around this region. However, the mixing and stabilisation processes inside of this zone have shown to be extremely complex. The level of swirl, burner outlet configuration and combustor expansion are very important variables that define the features of the CRZ.

Therefore, in this paper swirling flame dynamics are investigated using computational fluid dynamics (CFD) with commercial software (ANSYS). A new generic swirl burner operated under lean-premixed conditions was modelled. A variety of nozzles were analysed using several gaseous blends at a constant power output. The investigation was based on recognising the size and strength of the central recirculation zones. The dimensions and turbulence of the Central Recirculation Zone were measured and correlated to previous experiments. The results show how the strength and size of the recirculation zone are highly influenced by the blend and infer that it is governed by both the shear layer surrounding the Central Recirculation Zones (CRZ) and the gas composition

Abstract

The loss of cognitive function accompanying healthy aging is not associated with extensive or characteristic patterns of cell death, suggesting it is caused by more subtle changes in synaptic properties. In the hippocampal CA1 region, long-term potentiation requires stronger stimulation for induction in aged rats and mice and long-term depression becomes more prevalent. An age-dependent impairment of postsynaptic calcium homeostasis may underpin these effects. We have examined changes in presynaptic calcium signalling in aged mice using a transgenic mouse line (SyG37) that expresses a genetically encoded calcium sensor in presynaptic terminals. SyG37 mice showed an age-dependent decline in cognitive abilities in behavioural tasks that require hippocampal processing including the Barnes maze, T-maze and object location but not recognition tests. The incidence of LTP was significantly impaired in animals over 18 months of age. These effects of aging were accompanied by a persistent increase in resting presynaptic calcium, an increase in the presynaptic calcium signal following Schaffer collateral fibre stimulation, an increase in postsynaptic fEPSP slope and a reduction in paired-pulse facilitation. These effects were not caused by synapse proliferation and were of presynaptic origin since they were evident in single presynaptic boutons. Aged synapses behaved like younger ones when the extracellular calcium concentration was reduced. Raising extracellular calcium had little effect on aged synapses but altered the properties of young synapses into those of their aged counterparts. These effects can be readily explained by an age-dependent change in the properties or numbers of presynaptic calcium channels.