Post-fire recovery of Puya raimondii,vegetation and birds in the puna of Huascarán National Park,Perú

A large fire of 233 ha in Huascarán National Park in Peru provided an opportunity to compare plant and bird responses in burned and nearby unburned zones of the puna. Heights and live diameters of flagship Puya raimondii rosettes(assigned to four broad developmental phases), plant communities(66 species in 24 families and nine growth forms) and bird communities(77 species in six trophic guilds) were monitored after the fire. Although no mortality was observed, Puya raimondii plants were affected...     

A simple guideline to apply excitation-emission matrix spectroscopy (EEMs) for the characterization of dissolved organic matter (DOM) in anoxic marine sediments

Marine sediments represent a major carbon reservoir on Earth. Dissolved organic matter(DOM) in pore waters accumulates products and intermediates of carbon cycling in sediments. The application of excitation-emission matrix spectroscopy(EEMs) in the analysis of subseafloor DOM samples is largely unexplored due to the redoxsensitive matrix of anoxic pore water. Therefore, this study aims to investigate the interference caused by the matrix on EEMs and propose a guideline to prepare pore water sam...     

Ground-borne vibrations induced by impact pile driving: experimental assessment and mitigation measures

Impact pile driving is an interesting technique for the construction of deep foundations from a practical and economical point of view. However, the generalization of this technique can be restricted due to the excessive vibration levels that can be generated, which can be especially problematic in residential areas. However, different mitigation measures can be applied to prevent excessive vibration levels inside buildings located near construction sites. To compare its efficiency through a num...     

优化扫描速度在常见体重"双低"头颈CTA中的应用

目的:探讨双源CT对常见体重（79.4±14.5kg）及体质量指数（21kg/m20.05）。结论:双源CT可以对常见体重人群进行低辐射剂量、超低对比剂用量“双低”头颈联合CTA扫描。      

CT冠状动脉造影应用于急性胸痛临床实践研究进展

急性胸痛是一个重要的公共卫生问题,它可以造成高昂的医疗成本支出,并显著影响人民健康。急性冠脉综合征是急性胸痛血管性病变的主要原因,影像学检查可以快速、有效地对血管性病变进行排查诊断。本文主要就CT冠状动脉造影在急性胸痛中的临床实践做一综述。      

Geochemistry of Sediments from the Lopare Basin (Bosnia and Herzegovina): Implications for Paleoclimate, Paleosalinity, Paleoredox and Provenance

A combined inorganic and organic geochemical study was carried out on marls and mudstones collected from the Lower Miocene Lopare Basin, Bosnia and Herzegovina. A total of 46 samples collected from two boreholes, Pot 1 (depth of 193 m) and Pot 3 (depth of 344 m), showed that element abundances like boron (B), lithium (Li), strontium (Sr), uranium (U), chromium (Cr), nickel (Ni), magnesium (Mg), sodium (Na) and calcium (Ca) are much higher than average than in the upper continental crust (UCC). Chemical composition indicates at least two sources: (i) Mesozoic ophiolites occurring in the north of the investigated area, and (ii) dacito-andesitic pyroclastics (Mesozoic to Cenozoic). Lopare Basin sedimentation was influenced by strong evaporation resulting in a partly hypersaline lake, which formed during a warm climatic period, probably during the Miocene Climatic Optimum. A brief episode of humid climate conditions resulted in the basin filling-up and deposition of felsic sediments enriched in thorium (Th). Organic geochemistry shows that the majority of studied sediments contains predominantly immature to marginally mature algal organic matter (OM). The biomarker patterns are generally in agreement with the geological history of the Lopare Basin and inorganic and mineralogical data. Conversely, the molecular distribution of n-alkanes as reliable climatic and δ-MTTC as paleosalinity indicators do not support this conclusion.     

Fast clogging problem of open check dams and a new type suggestion:curved footed type open check dam

Driftwood is one of the important physical components in mountainous rivers which causes severe hazards due to the clogging of bridges, culverts,and narrow sections during floods. Therefore, the understanding of driftwood dynamics and mitigation measures are crucial for managing wood in rivers.Open check dams are the most commonly used engineering measure for preventing driftwood from reaching downstream areas. Nevertheless, these open check dams frequently lose their sediment transport function...     

Altitude as environmental filtering influencing phylogenetic diversity and species richness of plants in tropical mountains

Elucidating how multiple factors affect biodiversity and plant community assembly is a central issue in ecology, especially in vulnerable ecosystems such as tropical mountains. These studies are more relevant in global warming scenarios that induce the upward displacement of plant species towards reduced habitats and hostile environments in tropical mountains. This study aimed to analyze how altitude affects taxonomic and phylogenetic diversity in plant communities of tropical mountains. Thus, w...     

Glacier retreat,rock weathering and the growth of lichensin the Churup Valley,Peruvian Tropical Andes

The most heavily glacierized tropical range in the world – the Peruvian Cordillera Blanca-has been losing ice since the end of the Little Ice Age(LIA). In this study, the decline of the Churup glacier(9°28'18 " S; 77°25'02" W) and associated processes were documented employing multi-proxy approach including the analysis of remotely sensed images(1948-2016), the Schmidt hammer rock test and lichenometric dating. It is shown that Churup glacier has lost the vast majority of its estimated LIA extent(1.05 ± 0.1 km~2; 45.0×10~6-57.4×10~6 m~3). The rate of glacier retreat is documented to vary in space(SE, SW and NW-facing slopes) and time, with the peak between 1986 and 1995. With an area of 0.045 km~2 in 2016, it is expected that the complete deglaciation of the Churup valley is inevitable in the near future. Recently(post-LIA) exposed bedrock surfaces have shown higher R-values(54.2-66.4, AVG 63.3, STDEV 2.9) compared to pre-LIA exposed surfaces(46.1-59.3, AVG 50.1, STDEV 4.9), confirming the links to the duration of rock weathering. The Lichenometric dating is applied to recently exposed areas and elevations above 4800 m a.s.l., revealing only limited reliability and agreement with the age of deglaciation estimated from remotely-sensed images in such an environment.     

Macroscopically‐Zoned Grandite from the Garnetite Skarn of Meka Presedla (Kopaonik Mountain,Serbia)

The macroscopically-zoned grandite from the garnetite skarn of Meka Presedla (Kopaonik Mountain, Serbia) was studied with optical microscopy, electron microprobe analysis (EMPA), Fourier transform infra-red (FT–IR), and Raman methods. The EMPA results indicate that the main core–rim compositional variations (Ca2.93–2.97Mn0.05–0.06Mg0.00–0.01Al1.14–1.26Fe3+0.72–0.83Ti0.00–0.02Si2.97–3.02O12) slightly differ along the zones, showing evidence for a quasi-cyclic alternation of the oscillatory zoning nature. Among this, considerable variation is observed only by the Al–Fe3+ substitutions in the octahedral site. The EMPA also indicate that the grandite zones compositionally vary, mostly within ±1 and ±2 mol% of the homogeneity level range, that is, Grs64±1Adr36±1Sps2 (A), Grs62±1Adr38±1Sps2 (B), Grs59±2Adr40±2Sps2 (C), Grs58±2Adr41±2Sps2 (D), and Grs58±1Adr41±1Sps2 (E). Therefore, the investigated garnet can be considered as relatively highly homogeneous. The majority of compositions lie within the narrow miscibility region of 0.58±2相似文献