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121.
John Sutcliffe Stephen Hurst Ayman G. Awadallah Emma Brown Khaled Hamed 《水文科学杂志》2016,61(9):1557-1570
ABSTRACTH.E. Hurst spent some 60 years studying the Nile for the Egyptian government, and laid the foundation for a monumental set of hydrological records and investigations. His studies of the size of over-year reservoirs needed to maintain a given yield from Nile flows showed that this was greater than that based on random series. This finding, known as the Hurst phenomenon, was confirmed by other natural series and led to important advances in practical and theoretical statistics. His work led to the design of the Aswan High Dam and to continued research in Egypt.
Editor D. Koutsoyiannis; Guest editor E. Eris 相似文献
122.
The 28 February, 2006 Tiab earthquake (Mw 6.0), is the first earthquake to have occurred in the transition zone between the Zagros continental collision and the Makran subduction zone for which the aftershock sequence is recorded by a temporary local seismic network. The epicentral distribution of the aftershocks is diffuse and we cannot define a simple alignment at the surface. The depth of the aftershocks increases gently northward and they are primarily concentrated between 15 and 21 km depth, implying a deeper seismogenic layer than the Zagros. Very low-angle thrust faulting deduced from this local study supports thrusting of the Arabian plate beneath central Iran at the southeastern end of the Zagros as suggested previously based on teleseismic data. The focal mechanism of the main shock indicates a thrust mechanism similar to that of other strong earthquakes in this region, while most of the focal mechanisms of the aftershocks are dominantly strike-slip. We propose that the strike-slip mechanisms belong to right-lateral fault systems that accommodate differential motion at the transition between the Zagros collision zone and the Makran subduction zone. If so, this suggests that the convergence between Arabia and central Iran is at present accommodated along the transition zone by a partitioning process. 相似文献
123.
We documented the pattern of cell development in Euplotes charon. The ontogenesis of this species was similar to many of its congeners, except for the formation of the caudal cirri. In E. Charon, a caudal cirrus is formed posterior to each of the rightmost two or three dorsal kinety anlage in the proter, and the second
rightmost dorsal kinety in the opisthe. In addition, two caudal cirri are formed posterior to the rightmost dorsal kinety
in the opisthe. This pattern of development represents a completely new type. Based on our evaluation, and in comparison with
previous studies, we also conclude that the pattern of cell development is variable among species in the Euplotes genera. The variation is particularly evident during the formation of frontoventral and caudal cirri. Based on the segmentation
pattern of frontal-midventral transverse cirral anlagen, cirri reduction, and migration of frontoventral cirri, we identified
five types: the affinis-type, the eurystomus-type, the charon-type, the raikovi-type and orientalis-type. Euplotes (s. l.) can also be divided into three types based on the formation of caudal cirri: focardii-type, vannus-type and charon-type. Indeed, we conclude that the number (one or two) of marginal cirri should be given as much consideration as the genetic
separation. Given this, we reassessed the validity of using genetic separation to classify the group. Generally, the morphogenetic
data disagreed with the molecular data (SSrRNA gene sequences). Given these discrepancies, it is too early to draw conclusions
on the systematic arrangement of this species-rich taxon. 相似文献
124.
Gene sequence-based genealogies of scuticociliates are different from those produced by morphological analyses. For this reason,
11 representative scuticociliates and two ambiguously related genera were chosen to test the ability of combined phylogenetic
analyses using both gene sequences and morphological/morphogenetic characteristics. Analyses of both the SSrRNA gene sequences
and the combined datasets revealed a consistent branching pattern. While the terminal branches and the order level relationships
were generally well resolved, the family level relationships remain unresolved. However, two other trees based on ITS1-5.8S-ITS2
region sequences and morphological/morphogenetic characters showed limited information, due to a lack of informative sites
in these two datasets. Our data suggest, however, that the combined analysis of morphological/morphogenetic characters and
gene sequences did produce some changes to the phylogenetic estimates of this group. 相似文献
125.
El-Sayed M. Abdelrahman Eid. R. Abo-Ezz Khalid S. Essa T.M. El-Araby Khaled S. Soliman 《Geophysical Prospecting》2007,55(3):433-446
We have developed a least‐squares minimization approach to depth determination using numerical second horizontal derivative anomalies obtained from magnetic data with filters of successive window lengths (graticule spacings). The problem of depth determination from second‐derivative magnetic anomalies has been transformed into finding a solution to a non‐linear equation of the form, f(z) = 0. Formulae have been derived for a sphere, a horizontal cylinder, a dike and a geological contact. Procedures are also formulated to estimate the magnetic angle and the amplitude coefficient. We have also developed a simple method to define simultaneously the shape (shape factor) and the depth of a buried structure from magnetic data. The method is based on computing the variance of depths determined from all second‐derivative anomaly profiles using the above method. The variance is considered a criterion for determining the correct shape and depth of the buried structure. When the correct shape factor is used, the variance of depths is less than the variances computed using incorrect shape factors. The method is applied to synthetic data with and without random errors, complicated regionals, and interference from neighbouring magnetic rocks. Finally, the method is tested on a field example from India. In all the cases examined, the depth and the shape parameters are found to be in good agreement with the actual parameters. 相似文献
126.
Panon Latcharote Khaled Al-Salem Anawat Suppasri Tanuspong Pokavanich Shinji Toda Yogeesha Jayaramu Abdullah Al-Enezi Alanoud Al-Ragum Fumihiko Imamura 《Natural Hazards》2018,92(1):127-143
This paper explores the ways that Mongolian pastoral-nomadic herders and supporting aid organizations anticipate, interpret, and respond to dzud, a form of winter storm that prevents livestock grazing and often results in large-scale herd deaths. Analysis is drawn from organizational reports, government speeches, and mass media that have been collected to give a complex, multi-faceted understanding of the collection, distribution, and interpretation of data pertaining to the social and scientific construction of this natural hazard. Using critical discourse analysis, this study asks how herder perspectives and needs have been incorporated into reports and action plans of international development organizations. The collected documents provide insight into the ways that knowledge is constructed, disseminated and valued among policy makers, development planners and herders. Additionally, the findings indicate disagreement between stakeholders as to when to declare a national emergency, and how to best help herders respond to the increasing frequency of dzud. While some organizations rely on traditional recovery mechanisms, others have turned to technological solutions, all aiming to assist herders in adequately responding to and recovering from one dzud before another occurs. From the analysis of policy proposals, this study aims to understand and inform the ways that international development programs, government officials, and herders work to preserve pasturelands and herding lifestyles threatened by dzud. 相似文献
127.
This study uses geographic information systems to map the hotspots level changes in underground water quality based on pH, nitrate and conductivity in Amman, Zarqa and Balqa regions, Jordan using data from 57 wells. The chemical concentration for each parameter was obtained from the Water Authority of Jordan. The data were tested according to ISO/IEC 17025 standards by the Jordan Inorganic Laboratory of the Laboratories and Quality Department of Water Authority for 2004 and 2010 and were processed using Getis-Ord Gi statistics. The study indicated that there are periodic fluctuations for the values of selected chemical elements of groundwater that are localized, creating contamination hotspots within the study regions. The pH, nitrate and conductivity all indicated specific hotspots of higher than average values in 2004 and 2010 in the Zarqa region. The evidence indicates that there are two major localized areas of high value for all parameters centered in the western Zarqa region, an area dominated by urban infrastructure and irrigated lands. These findings have implications for the management of aquifer water quality through the identification of high-value hotspots. Because the aquifers in the regions are connected, understanding the hotspots with high pH, nitrate and conductivity values may enable improvements in the water quality across the aquifer systems in the regions. 相似文献
128.
Khaled A. Al-Wosabi Abdulwahab S. Alaug Ali A. A. Khudeir 《Arabian Journal of Geosciences》2014,7(7):2933-2940
The Pan-African (Neoproterozoic) low-grade ophiolitic fragment occurring to the south of Ataq City, Shabwah Province, southeastern central part of Yemen is positioned tectonically between the underlying Pre-Pan-African syntectonic granite infrastructure and the overlying Mesozoic–Cenozoic sedimentary successions. It is incomplete and differentiated in the field into (a) NW plunging nappes, namely a lower metagabbro nappe, and (b) the upper metavolcanic nappe. The sedimentary successions separated from each other by eastward dipping normal faults. These successions can be subdivided into three main rock units: Amran, Tawilah, and Hadramawt groups. The Amran Group is represented in the study area by Shuqra and Madbi formations. The Shuqra Formation consists mainly of highly fossiliferous carbonate facies yielding several terebratulids and rhynchonellids. It belongs to the Toracian–Oxfordian (or probably extend to Early Kimmeridgian) age. The Madbi Formation consists of sand–marl intercalations of Kimmeridgian–Early Tithonian age. The Tawilah Group is mainly composed of variegated unfossiliferous continental sandstones with few siltstone intercalations, and on the basis of its stratigraphic position, it is dated as Cretaceous (probably Early Cretaceous). The Hadramawt Group in the study area is represented by Umm er Radhuma Formation, which is widely distributed in the Arabian Gulf countries. 相似文献
129.
Contribution of shallow groundwater rapid fluctuation to soil salinization under arid and semiarid climate 总被引：4，自引：0，他引：4
Mohamed Khaled Ibrahimi Tsuyoshi Miyazaki Taku Nishimura Hiromi Imoto 《Arabian Journal of Geosciences》2014,7(9):3901-3911
Rising saline shallow groundwater and associated soil salinization problems are widespread especially in arid and semiarid areas. There have been numerous studies on groundwater-associated salinity, but more information is required on the effects of groundwater frequent and high fluctuations on soil salinization. In the present study, laboratory experiments and numerical simulations using HYDRUS-1D model were carried out for this purpose. The experimental and modeling results showed that groundwater fluctuation caused not only the accumulation of more salt in the soil profile compared to stable groundwater, but also an enhancement of the mechanism. Water table fluctuation induced a much greater spreading of the bromide (Br) tracer within the column than the constant water table. The Br content was on average five orders of magnitude greater under a fluctuating water table than under a constant one. Further, the numerical simulations showed that an increase in the groundwater fluctuation frequency brought about an increase in soil surface salinization under the same evaporation boundary conditions. Additional simulations with HYDRUS-1D were used to study the effects of various management strategies on soil salinization induced by shallow groundwater. Hence, by reducing the evaporation rate through the application of surface mulching, a significant reduction of salt concentration at the soil surface was observed. Moreover, frequent irrigations with small quantities were effective to reduce soil surface salt accumulation induced by saline shallow groundwater. 相似文献
130.
The western part of Yemen is largely covered by Tertiary volcanics and is bounded by volcanic margins to the west (Red Sea) and the south (Gulf of Aden). The Oligo–Miocene evolution of Yemen results from the interaction between the emplacement of the Afar plume, the opening of the Red Sea, and the westward propagation of the Gulf of Aden. Structural and microtectonic analyses of fault slip data collected in the field reveal that the volcanic margins of Yemen are affected by three main extensional tectonic events. The chronological order of these events is as follows: first E–W extension was associated with the emplacement of volcanic traps of Yemen, then NE–SW extension was related to the Red Sea rifting, and finally, the volcanic margin was submitted to N160°E extension, perpendicular to the overall trend of the Gulf of Aden, which we interpret as induced by the westward propagation of the oceanic ridge of the Gulf of Aden. 相似文献