7,387 research outputs found
A Mesozoic Clown Beetle Myrmecophile (Coleoptera: Histeridae)
Complex interspecies relationships are widespread among metazoans, but the evolutionary history of these lifestyles is poorly understood. We describe a fossil beetle in 99-million-year-old Burmese amber that we infer to have been a social impostor of the earliest-known ant colonies. Promyrmister kistneri gen. et sp. nov. belongs to the haeteriine clown beetles (Coleoptera: Histeridae), a major clade of ‘myrmecophiles’—specialized nest intruders with dramatic anatomical, chemical and behavioral adaptations for colony infiltration. Promyrmister reveals that myrmecophiles evolved close to the emergence of ant eusociality, in colonies of stem-group ants that predominate Burmese amber, or with cryptic crown-group ants that remain largely unknown at this time. The clown beetle-ant relationship has been maintained ever since by the beetles host-switching to numerous modern ant genera, ultimately diversifying into one of the largest radiations of symbiotic animals. We infer that obligate behavioral symbioses can evolve relatively rapidly, and be sustained over deep time
A comparative study on communication structures of Chinese journals in the social sciences
We argue that the communication structures in the Chinese social sciences
have not yet been sufficiently reformed. Citation patterns among Chinese
domestic journals in three subject areas -- political science and marxism,
library and information science, and economics -- are compared with their
counterparts internationally. Like their colleagues in the natural and life
sciences, Chinese scholars in the social sciences provide fewer references to
journal publications than their international counterparts; like their
international colleagues, social scientists provide fewer references than
natural sciences. The resulting citation networks, therefore, are sparse.
Nevertheless, the citation structures clearly suggest that the Chinese social
sciences are far less specialized in terms of disciplinary delineations than
their international counterparts. Marxism studies are more established than
political science in China. In terms of the impact of the Chinese political
system on academic fields, disciplines closely related to the political system
are less specialized than those weakly related. In the discussion section, we
explore reasons that may cause the current stagnation and provide policy
recommendations
Progress in diagnosis and treatment of basal cell carcinoma
Basal cell carcinoma is a common skin carcinogenesis that occurs in the epidermis and the basal layer of the skin.in general, basal cell carcinoma grows slowly, rarely metastasizes, but is locally invasive and destructive. The diagnosis is based on clinical manifestations, but the clinicopathological manifestations are different, and sometimes it is difficult to differentiate from pigmented nevus, malignant melanoma, etc. Therefore, skin biopsy is essential for the diagnosis and assessment of the risk of recurrence.There are many ways to treat basal cell carcinoma. This article reviews the diagnosis and treatment
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Analysis of interspecies adherence of oral bacteria using a membrane binding assay coupled with polymerase chain reaction-denaturing gradient gel electrophoresis profiling.
Information on co-adherence of different oral bacterial species is important for understanding interspecies interactions within oral microbial community. Current knowledge on this topic is heavily based on pariwise coaggregation of known, cultivable species. In this study, we employed a membrane binding assay coupled with polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) to systematically analyze the co-adherence profiles of oral bacterial species, and achieved a more profound knowledge beyond pairwise coaggregation. Two oral bacterial species were selected to serve as "bait": Fusobacterium nucleatum (F. nucleatum) whose ability to adhere to a multitude of oral bacterial species has been extensively studied for pairwise interactions and Streptococcus mutans (S. mutans) whose interacting partners are largely unknown. To enable screening of interacting partner species within bacterial mixtures, cells of the "bait" oral bacterium were immobilized on nitrocellulose membranes which were washed and blocked to prevent unspecific binding. The "prey" bacterial mixtures (including known species or natural saliva samples) were added, unbound cells were washed off after the incubation period and the remaining cells were eluted using 0.2 mol x L(-1) glycine. Genomic DNA was extracted, subjected to 16S rRNA PCR amplification and separation of the resulting PCR products by DGGE. Selected bands were recovered from the gel, sequenced and identified via Nucleotide BLAST searches against different databases. While few bacterial species bound to S. mutans, consistent with previous findings F. nucleatum adhered to a variety of bacterial species including uncultivable and uncharacterized ones. This new approach can more effectively analyze the co-adherence profiles of oral bacteria, and could facilitate the systematic study of interbacterial binding of oral microbial species
Changyuan Periphery Oilfield Economic Evaluation Method of Waterflood Potential Exploitation Measures
Changyuan periphery oilfield stable form of 5.2 million production requires fine waterflood to reduce the amplitude of production decline and relieve pressure. However, the effiency of Potential Exploitation Measures were uneven, affecting oil production and economic benefits. So there need to economic evaluation for measures and make measures adjustment. Assessed two different blocks’ economic through evaluated single oil and water well measures and the combined effect of blocks measures. Single well economic evaluation of oil and water wells measures include: measures validity, income, the incremental input-output ratio, payback period and efficiency 5 indicators. The combined effect of blocks measures evaluate by index P. In Changyuan periphery five demonstration area as an example, analysised of the best and worst economic effect of each blocks, and obtain a comprehensive evaluation results of the demonstration area. The evaluation results were consistent with actual situation, it should be widely applied
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