Climate change is one of the most important issues of today’s World. Climate scientists have concluded that the earth’s surface air temperature warmed by 0.6 ± 0.2℃ during the 20th century, accompanied by chan...Climate change is one of the most important issues of today’s World. Climate scientists have concluded that the earth’s surface air temperature warmed by 0.6 ± 0.2℃ during the 20th century, accompanied by changes in the hydrologic cycle. Of all the climate elements, temperature plays a major role in detecting climate change brought about by urbanization and industrialization. This study focuses on the variability and trends of the mean annual, seasonal and monthly surface air temperature in Taiz city, Republic of Yemen, during the period 1979-2006. The results of the analysis of the whole period reveal a statistically significant increasing trend in practically all the months and seasons. A tendency has also been observed towards warmer years, with significantly warmer summer and spring periods and slightly warmer autumn and winter, an increase of 1.79℃ and 1.18℃ has been observed in the mean summer and mean winter temperature, respectively. Positive trends of about 1.5℃ in the annual mean temperature were found for the whole period. The air temperature time series are analyzed, so that the variability and trends can be described.展开更多
The negative effects of fossil fuels have forced many countries to explore clean energy sources that are both environmenttally more suitable and renewable. In this study, wind characteristics and assessment of wind en...The negative effects of fossil fuels have forced many countries to explore clean energy sources that are both environmenttally more suitable and renewable. In this study, wind characteristics and assessment of wind energy potential, were analyzed using the wind speed data measured during the period 1995-2001 at 10 m height of Al-Mokha, located in the west of Taiz, in the southwest of Yemen, subjected to 2-parameter Weibull analysis. Based on these data, it was found that the monthly mean wind speed ranged from 3.50 m/s in June to 7.94 m/s in November, the monthly values of Weibull shape parameter (k), ranged from 3.09 to 6.26, while the value of scale parameter (c) ranged from 3.91 to 8.63 m/s and the monthly wind power density ranged from 33.08 to 352.43 W/m2. The seasonal mean wind speed data ranged from 3.61 to 7.56 m/s, while the wind power density was ranged from 36.62 to 328.59 W/ m2 for summer and winter, respectively.展开更多
The coastline changes along Yemen＇s the Red Sea （Al-muka, Al-khohah, Al-tiaf, Ras Katib and Al- Urji spits） were studied using a series of landsat images （MSS, TM and ETM ＋ , 1972, 1989, 2000, 2006）, coupled wit...The coastline changes along Yemen＇s the Red Sea （Al-muka, Al-khohah, Al-tiaf, Ras Katib and Al- Urji spits） were studied using a series of landsat images （MSS, TM and ETM ＋ , 1972, 1989, 2000, 2006）, coupled with geomorphological, sedimentological and meteorological findings. Comparison of satellite images provided a viable means for establishing long-term coastal changes （accretion and erosion） as observed in the studied spits （Al-Urj, Ras Sham, Ras Maemoon, Ras Katib, Al-Mandar, Nukhaylah, Mujamilah, Ras Ashab Abu-Zahr and Mukha）. The rate of the spit accretion has the greatest value up to 89 pixel/year corresponding to 72 290 m2/year in Mukha, while the spit erosion shows greatest value up to 131 pixel/year corresponding to 106 404 m2/year in Mujamilab. The patterns of accretion and erosion along the spits depend on the spit direction, natural processes mainly of wave-induced longshore currents, the sediments supply and depth of sea.展开更多
Rift formation is a crucial topic in global tectonics. The Yemen rift-related area is one of the most important provinces, being connected to the rifting processes of the Gulf of Aden, the Red Sea and Afar Triangle. I...Rift formation is a crucial topic in global tectonics. The Yemen rift-related area is one of the most important provinces, being connected to the rifting processes of the Gulf of Aden, the Red Sea and Afar Triangle. In this paper, a review of the Yemen volcanic province and its relations with the Red Sea rifting are presented. Tertiary continental extension in Yemen resulted in the extrusion of large volumes of effusive rocks. This magmatism is divided in the Oligo-Miocene Yemen Trap Series (YTS) separated by an unconformity from the Miocene-Recent Yemen Volcanic Series (YVS). Magmas of the YTS were erupted during the synrift phase and correlate with the first stage of sea-floor spreading of the Red Sea and the Gulf of Aden (30 - 15 Ma), whereas the magmas of the YVS were emplaced during the post rift phase (10 - 0 Ma). A continental within plate character is recognized for both the YTS and YVS basalts. The YTS volcanic rocks are contemporaneous with, and geochemically similar to, the Ethiopian rift volcanism, just as the volcanic fields of the YVS are geochemically alike to most of the Saudi Arabian volcanics. YTS and YVS have analogous SiO2 ranges, but YVS tend to have, on average, higher alkalis and MgO contents than YTS. Fractional crystallization processes dominate geochemical variations of both series. Primitive magmas (MgO > 7.0%) are enriched in incompatible elements and LREEs with respect to primitive mantle, but YVS are more enriched than YTS. To first order, the different geochemical patterns agree with different degrees of partial melting of an astenospheric mantle source: 25% - 30% of partial melting for YTS and 10% - 3% for YVS. Secondly, the higher degree of enrichment in incompatible elements of YVS reflects also greater contribution of a lithospheric mantle component in their source region.展开更多
Magmatic Cu-Ni sulfide deposits are generally associated with mafic-ultramafic rocks and it has not been reported that lamprophyre is one of the surrounding rocks of Cu-Ni sulfide deposits.The Dhi Samir deposit in Yem...Magmatic Cu-Ni sulfide deposits are generally associated with mafic-ultramafic rocks and it has not been reported that lamprophyre is one of the surrounding rocks of Cu-Ni sulfide deposits.The Dhi Samir deposit in Yemen,however,is a rare example of Cu-Ni deposits which are hosted in lamprophyre dikes.In this paper,comprehensive research is made on petrology,petrochemistry and isotope geochemistry for Cu-Ni-bearing rocks in the Dhi Samir area and the results show that dark rocks related to Cu-Ni orebodies are sodium-weak potassium and belong to calc-alkaline series lamprophyre,especially camptonite,characterized by enriched alkali,iron and titanium.In these rocks large-ion-lithophile elements are obviously concentrated,while high field strength elements slightly depleted,showing clear negative anomalies of Ta and Nb,and weak deficiency of Ti.TheΣREE is very high（225.67-290.05 ppm） and the REE partition curves are flat and right-inclined,featuring a LREE-enriched pattern with low negative Eu anomalies.Study of magmatic source areas indicates that the rocks have low（87Sr/86Sr） and highεNd（t）,and the magmas were probably derived from the enriched mantle I（EM-I） end-member.Based on the LA-ICPMS on zircon U-Pb isotope dating,the lamprophyre in the Dhi Samir mining area has an age of 602±2.6 Ma,indicating that the rock was formed in the late Proterozoic and in an intraplate setting due to magmatism of an extensional environment in the post-Pan-Africa orogeny.展开更多
Background and Aims: Patients on hemodialysis (HD) are at high risk of viral hepatitis due to high number of blood transfusion sessions, prolonged vascular access, high exposure to infected patients and contaminated e...Background and Aims: Patients on hemodialysis (HD) are at high risk of viral hepatitis due to high number of blood transfusion sessions, prolonged vascular access, high exposure to infected patients and contaminated equipment, or cross contamination from the dialysis circuits and pose problems in the management of patients in the renal dialysis units. This study was done to determine the prevalence of Hepatitis B virus (HBV) & Hepatitis C virus (HCV), in patients on hemodialysis in Zabeed City, Yemen Republic, and address the major risk factors for transmission of these viruses among HD patients. Materials and Methods: In this cross-sectional study, during June, 2013 to October, 2014, a total of 243 chronic hemodialysis patients were tested. Patients were selected from many regions by cluster sampling from Zabeed public hospital, (hemodialysis center) in Zabeed City, Yemen Republic. A close ended and multiple choice-based questionnaires were completed and HBsAg and anti-HCV antibodies were assessed using third generation enzyme linked immunoassay kit as serological testing and data were analyzed using the SPSS-20 software. Results: The overall prevalence of positive HBsAg was (48.83%) while positive anti-HCV was (46.01%) and (5.16%) mixed infection with HBV and HCV. Analysis of risk factors in patients with HBV & HCV infection is showed the history of blood transfusion and duration of hemodialysis was found to be a statistically significant (P < 0.05) as risk factor for HBV and HCV infection. Conclusion: The evaluation suggests that blood transfusion and duration of hemodialysis may be the main most important risk factor for HBV and HCV infection among hemodialysis patients.展开更多
The present study is devoted to understanding the evolution of the Upper Jurassic Sab'atayn Formation in the Marib-Shabwa Basin,Yemen,through a sequence stratigraphic analysis based on integrating datasets of sedi...The present study is devoted to understanding the evolution of the Upper Jurassic Sab'atayn Formation in the Marib-Shabwa Basin,Yemen,through a sequence stratigraphic analysis based on integrating datasets of sedimentology,seismic sections,and well logs.The Sab'atayn Formation(Tithonian age)is represented by a series of clastic and evaporites that were deposited under fluvio-deltaic to prodeltaic settings.It is divided into four members including Yah(at the base),upwards to Seen,Alif,and Safir at the top.Two third-order depositional sequences were determined for the Tithonian succession which were separated by three sequence boundaries.These sequences were classified into their systems tracts signifying several sedimentation patterns of progradational,aggradational,and retrogradational parasequence sets.The first depositional sequence corresponds to the early-middle Tithonian Yah and Seen units that can be classified into lowstand,transgressive,and highstand systems tracts.The second sequence comprises the late Tithonian Alif unit that can be subdivided into transgressive and highstand systems tracts.The sandy deposits of the Alif Member(highstand deposits)represent the most productive hydrocarbon reservoir in the basin.The Upper Jurassic sediments in the study area were resulted from a combination of eustatic and tectonic effects.展开更多
文摘Climate change is one of the most important issues of today’s World. Climate scientists have concluded that the earth’s surface air temperature warmed by 0.6 ± 0.2℃ during the 20th century, accompanied by changes in the hydrologic cycle. Of all the climate elements, temperature plays a major role in detecting climate change brought about by urbanization and industrialization. This study focuses on the variability and trends of the mean annual, seasonal and monthly surface air temperature in Taiz city, Republic of Yemen, during the period 1979-2006. The results of the analysis of the whole period reveal a statistically significant increasing trend in practically all the months and seasons. A tendency has also been observed towards warmer years, with significantly warmer summer and spring periods and slightly warmer autumn and winter, an increase of 1.79℃ and 1.18℃ has been observed in the mean summer and mean winter temperature, respectively. Positive trends of about 1.5℃ in the annual mean temperature were found for the whole period. The air temperature time series are analyzed, so that the variability and trends can be described.
文摘The negative effects of fossil fuels have forced many countries to explore clean energy sources that are both environmenttally more suitable and renewable. In this study, wind characteristics and assessment of wind energy potential, were analyzed using the wind speed data measured during the period 1995-2001 at 10 m height of Al-Mokha, located in the west of Taiz, in the southwest of Yemen, subjected to 2-parameter Weibull analysis. Based on these data, it was found that the monthly mean wind speed ranged from 3.50 m/s in June to 7.94 m/s in November, the monthly values of Weibull shape parameter (k), ranged from 3.09 to 6.26, while the value of scale parameter (c) ranged from 3.91 to 8.63 m/s and the monthly wind power density ranged from 33.08 to 352.43 W/m2. The seasonal mean wind speed data ranged from 3.61 to 7.56 m/s, while the wind power density was ranged from 36.62 to 328.59 W/ m2 for summer and winter, respectively.
文摘The coastline changes along Yemen＇s the Red Sea （Al-muka, Al-khohah, Al-tiaf, Ras Katib and Al- Urji spits） were studied using a series of landsat images （MSS, TM and ETM ＋ , 1972, 1989, 2000, 2006）, coupled with geomorphological, sedimentological and meteorological findings. Comparison of satellite images provided a viable means for establishing long-term coastal changes （accretion and erosion） as observed in the studied spits （Al-Urj, Ras Sham, Ras Maemoon, Ras Katib, Al-Mandar, Nukhaylah, Mujamilah, Ras Ashab Abu-Zahr and Mukha）. The rate of the spit accretion has the greatest value up to 89 pixel/year corresponding to 72 290 m2/year in Mukha, while the spit erosion shows greatest value up to 131 pixel/year corresponding to 106 404 m2/year in Mujamilab. The patterns of accretion and erosion along the spits depend on the spit direction, natural processes mainly of wave-induced longshore currents, the sediments supply and depth of sea.
文摘Rift formation is a crucial topic in global tectonics. The Yemen rift-related area is one of the most important provinces, being connected to the rifting processes of the Gulf of Aden, the Red Sea and Afar Triangle. In this paper, a review of the Yemen volcanic province and its relations with the Red Sea rifting are presented. Tertiary continental extension in Yemen resulted in the extrusion of large volumes of effusive rocks. This magmatism is divided in the Oligo-Miocene Yemen Trap Series (YTS) separated by an unconformity from the Miocene-Recent Yemen Volcanic Series (YVS). Magmas of the YTS were erupted during the synrift phase and correlate with the first stage of sea-floor spreading of the Red Sea and the Gulf of Aden (30 - 15 Ma), whereas the magmas of the YVS were emplaced during the post rift phase (10 - 0 Ma). A continental within plate character is recognized for both the YTS and YVS basalts. The YTS volcanic rocks are contemporaneous with, and geochemically similar to, the Ethiopian rift volcanism, just as the volcanic fields of the YVS are geochemically alike to most of the Saudi Arabian volcanics. YTS and YVS have analogous SiO2 ranges, but YVS tend to have, on average, higher alkalis and MgO contents than YTS. Fractional crystallization processes dominate geochemical variations of both series. Primitive magmas (MgO > 7.0%) are enriched in incompatible elements and LREEs with respect to primitive mantle, but YVS are more enriched than YTS. To first order, the different geochemical patterns agree with different degrees of partial melting of an astenospheric mantle source: 25% - 30% of partial melting for YTS and 10% - 3% for YVS. Secondly, the higher degree of enrichment in incompatible elements of YVS reflects also greater contribution of a lithospheric mantle component in their source region.
文摘Magmatic Cu-Ni sulfide deposits are generally associated with mafic-ultramafic rocks and it has not been reported that lamprophyre is one of the surrounding rocks of Cu-Ni sulfide deposits.The Dhi Samir deposit in Yemen,however,is a rare example of Cu-Ni deposits which are hosted in lamprophyre dikes.In this paper,comprehensive research is made on petrology,petrochemistry and isotope geochemistry for Cu-Ni-bearing rocks in the Dhi Samir area and the results show that dark rocks related to Cu-Ni orebodies are sodium-weak potassium and belong to calc-alkaline series lamprophyre,especially camptonite,characterized by enriched alkali,iron and titanium.In these rocks large-ion-lithophile elements are obviously concentrated,while high field strength elements slightly depleted,showing clear negative anomalies of Ta and Nb,and weak deficiency of Ti.TheΣREE is very high（225.67-290.05 ppm） and the REE partition curves are flat and right-inclined,featuring a LREE-enriched pattern with low negative Eu anomalies.Study of magmatic source areas indicates that the rocks have low（87Sr/86Sr） and highεNd（t）,and the magmas were probably derived from the enriched mantle I（EM-I） end-member.Based on the LA-ICPMS on zircon U-Pb isotope dating,the lamprophyre in the Dhi Samir mining area has an age of 602±2.6 Ma,indicating that the rock was formed in the late Proterozoic and in an intraplate setting due to magmatism of an extensional environment in the post-Pan-Africa orogeny.
文摘Background and Aims: Patients on hemodialysis (HD) are at high risk of viral hepatitis due to high number of blood transfusion sessions, prolonged vascular access, high exposure to infected patients and contaminated equipment, or cross contamination from the dialysis circuits and pose problems in the management of patients in the renal dialysis units. This study was done to determine the prevalence of Hepatitis B virus (HBV) & Hepatitis C virus (HCV), in patients on hemodialysis in Zabeed City, Yemen Republic, and address the major risk factors for transmission of these viruses among HD patients. Materials and Methods: In this cross-sectional study, during June, 2013 to October, 2014, a total of 243 chronic hemodialysis patients were tested. Patients were selected from many regions by cluster sampling from Zabeed public hospital, (hemodialysis center) in Zabeed City, Yemen Republic. A close ended and multiple choice-based questionnaires were completed and HBsAg and anti-HCV antibodies were assessed using third generation enzyme linked immunoassay kit as serological testing and data were analyzed using the SPSS-20 software. Results: The overall prevalence of positive HBsAg was (48.83%) while positive anti-HCV was (46.01%) and (5.16%) mixed infection with HBV and HCV. Analysis of risk factors in patients with HBV & HCV infection is showed the history of blood transfusion and duration of hemodialysis was found to be a statistically significant (P < 0.05) as risk factor for HBV and HCV infection. Conclusion: The evaluation suggests that blood transfusion and duration of hemodialysis may be the main most important risk factor for HBV and HCV infection among hemodialysis patients.
文摘The present study is devoted to understanding the evolution of the Upper Jurassic Sab'atayn Formation in the Marib-Shabwa Basin,Yemen,through a sequence stratigraphic analysis based on integrating datasets of sedimentology,seismic sections,and well logs.The Sab'atayn Formation(Tithonian age)is represented by a series of clastic and evaporites that were deposited under fluvio-deltaic to prodeltaic settings.It is divided into four members including Yah(at the base),upwards to Seen,Alif,and Safir at the top.Two third-order depositional sequences were determined for the Tithonian succession which were separated by three sequence boundaries.These sequences were classified into their systems tracts signifying several sedimentation patterns of progradational,aggradational,and retrogradational parasequence sets.The first depositional sequence corresponds to the early-middle Tithonian Yah and Seen units that can be classified into lowstand,transgressive,and highstand systems tracts.The second sequence comprises the late Tithonian Alif unit that can be subdivided into transgressive and highstand systems tracts.The sandy deposits of the Alif Member(highstand deposits)represent the most productive hydrocarbon reservoir in the basin.The Upper Jurassic sediments in the study area were resulted from a combination of eustatic and tectonic effects.
