Serpentinized Peridotites at the North Part of the Wadi Allaqi District (Egypt): Implications for the Tectono-Magmatic Evolution of Fore-arc Crust

The Neoproterozoic Allaqi-Heiani suture （800-700 Ma） in the south Eastern Desert of Egypt is the northernmost linear ophiolitic belt that defines an arc-arc suture in the Arabian- Nubian shield （ANS）. The Neoproterozoic serpentinized peridotites represent a distinct lithology of dismembered ophiolites along the Allaqi-Heiani suture zone. The alteration of peridotites varies, some contain relicts of primary minerals （Cr-spinel and olivine） and others are extremely altered, especially along thrusts and shear zones, with development of talc, talc-carbonate and quartz-carbonate. The fresh cores of the chromian spinels are rimmed by ferritchromite and Cr- magnetite. The fresh chromian spinels have high Cr# （0.62 to 0.79）, while Mg# shows wider variation （0.35-0.59）. High Cr# in the relict chromian spinels and Fo content in the primary olivines indicate that they are residual peridotites after extensive partial melting. The studied ophiolitic upper mantle peridotites are highly depleted and most probably underwent high degrees of partial melting at a supra-subduction zone setting. They can be produced by up to -20%-22% dynamic melting of a primitive mantle source. The mineralogical and geochemical features of the studied rocks reflect that the mantle peridotites of the north part of the Wadi Allaqi district are similar to the fore-arc peridotites of a supra-subduction zone.     

Interstellar cyanomethane

We have made an observational study of the newly identified cyanomethane radical CH2CN and the possibly related species CH3CN with the goals of (1) elucidating the possible role of reactions of the type CnHm(+) + N in astrochemistry, and (2) providing a possible test of Bates's models of dissociative electron recombination. We find a remarkably different abundance ratio CH2CN/CH3CN in TMC-1 and Sgr B2, which we deduce is a result of the large difference in temperature of these objects. Studies of CH2CN and CH3CN in other sources, including two new detections of CH2CN, support this conclusion and are consistent with a monotonic increase in the CH2CN/CH3CN ratio with decreasing temperature over the range 10-120 K. This behavior may be explained by the destruction of CH2CN by reaction with O. If this reaction does not proceed, then CH2CN and CH3CN are concluded to form via different chemical pathways. Thus, they do not provide a test of Bates's conjectures (they do not both form from CH3CNH+). CH2CN is then likely to form via C2H4(+) + N --> CH2CNH+, thus demonstrating the viability of this important reaction in astrochemistry. The T dependence of the CH2CN/CH3CN ratio would then reflect the increasing rate of the C2H4(+) + N reaction with decreasing temperature.     

Real-time PCR and NASBA for rapid and sensitive detection of Vibrio cholerae in ballast water

Transport of ballast water is one major factor in the transmission of aquatic organisms, including pathogenic bacteria. The IMO-guidelines of the Convention for the Control and Management of Ships' Ballast Water and Sediments, states that ships are to discharge <1 CFU per 100 ml ballast water of toxigenic Vibrio cholerae, emphasizing the need to establish test methods. To our knowledge, there are no methods sensitive and rapid enough available for cholera surveillance of ballast water. In this study real-time PCR and NASBA methods have been evaluated to specifically detect 1 CFU/100ml of V. cholerae in ballast water. Ballast water samples spiked with V. cholerae cells were filtered and enriched in alkaline peptone water before PCR or NASBA detection. The entire method, including sample preparation and analysis was performed within 7 h, and has the potential to be used for analysis of ballast water for inspection and enforcement control.     

Meiofauna as descriptor of tourism-induced changes at sandy beaches

Tourism has long been considered as a 'clean industry' with almost no negative effects on the environment. This study demonstrated, in two different coastal systems (Mediterranean and Baltic), that tourism related activities are particularly affecting the sandy beach meio- and nematofauna in the upper beach zone, the specific ecotone in which many meiofauna species from both the marine and the terrestrial environment congregate. Tourist upper beaches are characterized by a lower % total organic matter (%TOM), lower densities, lower diversities (absence of Insecta, Harpacticoida, Oligochaeta, terrestrial nematodes and marine Ironidae nematodes) and higher community stress compared to nearby non-tourist locations. The %TOM was found to be the single most important factor for the observed differences in meiofauna assemblage structure at tourist versus non-tourist beaches in both the Mediterranean and the Baltic region. The free-living nematode assemblages from tourist upper zones depart significantly from expectations based on random selections from the regional nematode species pool. Furthermore upper zone assemblages are characterised by a low species diversity consisting of taxonomically closely related nematode species with r-strategist features. Generally, faunal differences between tourist and non-tourist beaches are decreasing towards the lower beach zones.     

OPTIMIZATION OF A CHROMATOGRAPHIC ANALYSIS IN REVERSED PHASE LIQUID CHROMATOGRAPHY

The automatic procedures for optimizing the composition of a binary mobile phase in reversed phaseliquid chromatography have been intensively studied for the past ten years.The performance of theseprocedures,based on either the black box approach or on other methods such as the experimentaldesign,are very often limited by the large number of time-consuming experimental runs that arenecessary for the determination of the analysis conditions to be optimized.The proposed method reduces this number of experiments:two experiments,run under linearvariation of the composition of the binary mobile phase(the linear gradient elution mode),make itpossible to determine the mobile phase composition corresponding to the maximum resolution betweenpeaks,the final analysis being assumed to be carried out under isocratic conditions.The method requires two steps:the determination of the retention characteristics for each solute,which depend upon the composition of the mobile phase;the selection of the optimum composition ofthe isocratic mobile phase,by using a criterion such as the maximum resolution normalized by the squareroot of the plate number,for the least separated pair of adjacent peaks.The interest,performance and limits of use of such an optimization procedure are discussed by meansof the chromatographic analysis of different complex mixtures.     

What Is Hatching in the Egg?

We present observations of several large two-ribbon flares observed with both the Transition Region and Coronal Explorer (TRACE) and the soft X-ray telescope on Yohkoh. The high spatial resolution TRACE observations show that solar flare plasma is generally not confined to a single loop or even a few isolated loops but to a multitude of fine coronal structures. These observations also suggest that the high-temperature flare plasma generally appears diffuse while the cooler ( less, similar2 MK) postflare plasma is looplike. We conjecture that the diffuse appearance of the high-temperature flare emission seen with TRACE is due to a combination of the emission measure structure of these flares and the instrumental temperature response and does not reflect fundamental differences in plasma morphology at the different temperatures.     

Ecological status and uses of juniper species in the cold desert environment of the Lahaul valley, North-western Himalaya, India

The juniper species Juniperus polycarpos C. Koch, J. indica Bertol. and J. communis L. var. saxatilis (Pallas) are important elements of the forest vegetation in Lahaul valley in the north-western Himalaya. Their ability to grow under the barren and xeric conditions of cold deserts makes them particularly suited for afforestation programmes under these ecological conditions. In the Lahaul valley, juniper species are used as subsistence resources and for religious purposes. Excessive removal of juniper wood and leaves by the local population, overgrazing, habitat fragmentation and low regeneration potential are the main obstacles to conservation of juniper forests in this region. The present study was carried out to assess density, basal area and importance value index (IVI) of the local vegetation as well as uses and amounts of juniper wood and leaves removed from the local forests. Pressure on relict juniper forests due to grazing animals and intensive removal of wood and leaves by the local population was found to be greater at an altitude above 3,000 m. The results of the study demonstrated that the different juniper species were adapted to specific altitude ranges. A higher species density was recorded at lower altitude except for J. indica which was only present at high altitude (>3,200 m) on south-facing slopes. Density, basal area and IVI of J. polycarpos were higher at Hinsa (2,700 m) than at Jahlma (3,000 m). The rapid loss of vegetation due to overuse and habitat degradation has made the conservation of juniper forests an important priority in the Lahaul valley. J. polycarpos at lower altitude and J. indica at higher altitude are ecologically the more suitable species for the successful implementation of conservation programmes. The support of rehabilitation programmes by regional authorities is essential for the reestablishment of the local juniper forests.     

遥感和GIS技术应用于伊拉克南部Basrah省土地利用/覆盖变化及城市扩张研究

In recent years, land use/cover dynamic change has become a key subject that needs to be dealt with in the study of global environmental change. In this paper, remote sensing and geographic information systems (GIS) are integrated to monitor, map, and quantify the land use/cover change in the southern part of Iraq (Basrah Province was taken as a case) by using a 1:250 000 mapping scale. Remote sensing and GIS software were used to classify Landsat TM in 1990 and Landsat ETM+ in 2003 imagery into five land use and land cover (LULC) classes: vegetation, sand, urban area, unused land, and water bodies. Supervised classification and normalized difference build-up index (NDBI) were used respectively to retrieve its urban boundary. An accuracy assessment was performed on the 2003 LULC map to determine the reliability of the map. Finally, GIS software was used to quantify and illustrate the various LULC conversions that took place over the 13-year span of time. Results showed that the urban area had increased by the rate of 1.2% per year, with area expansion from 3 299.1 km² in 1990 to 3 794.9 km² in 2003. Large vegetation area in the north and southeast were converted into urban construction land. The land use/cover changes of Basrah Province were mainly caused by rapid development of the urban economy and population immigration from the countryside. In addition, the former government policy of “returning farmland to transportation and huge expansion in military camps” was the major driving force for vegetation land change. The paper concludes that remote sensing and GIS can be used to create LULC maps. It also notes that the maps generated can be used to delineate the changes that take place over time. Supported by the Al-Basrah University, Iraq, the Geo-information Science and Technology Program (No. IRT 0438)China).     

2003年十胜近海地震随后的余滑时空分布：断层带摩擦性质变化的推论

2003年9月25日(世界时)十胜近海地震(Mw～8．0)随后的GPS时间序列揭示出了显著形变。我们采用“网络反演滤波”技术，对震后30天内后续断层滑动的时空演变进行了反演。后续断层滑动集中在同震破裂带附近，即在2003年地震断裂带、1968年十胜近海地震和1973年根室近海地震震源区之间的位置。反演表明，2003年地震断裂带中断层滑动速率衰减迅速，而周围地区衰减速度较慢。后续断层滑动地区的应力一速度路径大致遵循dτ／d In(v)～0．6MPa，这暗示着稳态速度强化摩擦。尽管不能排除其他的解释，但在沿走向的方向上，同震破裂和后续断层滑动互补的空间模型还是可能表明了摩擦特征的空间变化。     

亚洲第四系的主要划分及其岩性和生物地层学意义

这个专题讨论会是作为INQUA亚太地区地层分委员会的第四次国际专题讨论会举办的。1985年,国际地层委员会(ISC)批准了意大利南部Vrica地区的上新世-更新世界线。此后,1987年在渥太华召开的Ⅻ届INQUA大会通过了更新世地层划分分委员会(主席G.M.Richmond)的建议,即把下更新统-中更新统界线暂定在松山-布容极