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61.
Cacops, one of the most distinctive Paleozoic amphibians, is part of a clade of dissorophoid temnospondyls that diversified in the
equatorial region of Pangea during the Late Carboniferous and Early Permian, persisting into the Late Permian in Central Russia
and China. Dissorophids were a successful group of fully terrestrial, often spectacularly armoured predators, the only amphibians
apparently able to coexist with amniotes when the latter started to dominate terrestrial ecosystems. In this paper, we describe
excellent new skulls from the Early Permian of Oklahoma attributed to Cacops, Cacops morrisi sp. nov. and provide for the first time detailed information about this iconic dissorophid. These specimens show anatomical
and ontogenetic features that will impact on future studies on the evolution of terrestriality in tetrapods. For example,
the large, posteriorly closed tympanic embayment has fine striations on an otherwise smooth surface, documenting the oldest
known clear evidence for the presence of a tympanic membrane in the fossil record, a structure that is used for hearing airborne
sound in extant tetrapods. The skull of C. morrisi also has several features associated with predatory behaviour, indicating that this dissorophid may have been one of the
top terrestrial predators of its time. 相似文献
62.
以下扬子区44个代表性剖面的资料为基础,求导佩尔特提出的D函数和熵函数,编制出早石炭世各时期的沉积厚度趋势图和佩尔特岩相图,研究其沉积特征和古地理,对阐明该区地质发展史和地层控矿条件提供空间分布上的有用信息。 相似文献
63.
Early adolescence (12–13 years old) is a critical but under-researched demographic for the formation of attitudes related to climate change. We address this important area by exploring adolescent views about climate change. This paper presents opinions collected from surveys of 463 1st-year secondary school students (12–13 years old) in public secondary schools in inner-urban centres in Austria and Australia on whether climate change is (1) something about which to worry, (2) caused by humans and (3) happening now. Eligible respondents in both countries showed similar levels of agreement that climate change was probably or definitely something we should (1) worry about (84.6% Austria, 89.1% Australia), which is significantly higher than either country’s adult population. Eligible respondents agreed that climate change probably or definitely is (2) caused by humans (75.6% Austria, 83.6% Australia) and that climate change is probably or definitely something that is (3) happening now (73.1% Austria, 87.5% Australia). Their response differed from the respective adult populations, but in opposite directions. Our results suggest that socio-cultural worldview may not have as much influence on this age group as it does on the respective adult populations and suggests that this age group would be receptive and ready for climate science education and engagement initiatives.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01356-2) contains supplementary material, which is available to authorized users. 相似文献
64.
J. Bosch F. Strozzi T. J. Snee J. A. Hare J. M. Zaldívar 《Journal of Loss Prevention in the Process Industries》2004,17(6):389-395
In this work, we have analysed the use of pressure instead of temperature measurements for the early warning detection of runaway initiation. This is possible due to the fact that our runaway criterion, i.e. div>0, does not depend specifically on which state space variable we are using for divergence calculation. A series of runaway experiments, carried out in a 250 l pilot-scale reactor, has been used to compare the results. In accordance with previous analysis, we show that by using temperature, early detection of runaway initiation is achieved. Analogously to temperature, pressure may be also used for runaway detection. By comparing the different types of reactive systems analysed (vapour and gassy), it can be observed that temperature works better, in terms of earlier detection, than pressure but the differences are more pronounced for vapour than for gassy systems. 相似文献
65.
湘北华容地区小墨山花岗岩体SHRIMPU—Pb年龄及地球化学特征 总被引:2,自引:0,他引:2
小墨山岩体侵位于中元古代冷家溪群中,由两期侵入体组成,早期为粗中粒—中粒斑状黑云母二长花岗岩;末期为细粒黑(二)云母二长花岗岩。通过锆石SHRIMP U-Pb法测得岩体侵位年龄为122.5±2.1 Ma(2σ),MSWD=1.9,成岩时代为早白垩世。主元素中,SiO2变化于67.20%~75.16%,K2O含量高,且K2O>Na2O,K2O/Na2O为1.16~1.72;ASI值变化于0.96~1.10之间,平均1.02,属准铝质-微过铝质、高钾钙碱性系列。岩石明显富集大离子亲石元素,亏损高场强元素,Rb/Sr=0.27~15.13;Nb/Ta=15.9~17.1,为锶和铌亏损型。ΣREE总体较高,重稀土含量相对较高,轻重稀土分馏稍弱,ΣCe/ΣY为0.49~6.18,(La/Yb)N为0.66~15.54。有较高的εNd(t),为-6.8~-8.7;T2DM相对较小(1.47~1.62 Ga)。综合研究表明,小墨山花岗岩石为壳源型富黑云母过铝花岗岩类(CPG),其成因应为下地壳物质和上地壳物质混合而成,与花岗岩底侵作用或注入地壳中的幔源岩浆有关,形成的构造背景为陆内挤压造山向非造山转换的后造山拉张环境,是在... 相似文献
66.
Dr. I. V. Tsvetkova T. V. Zolotukhina V. A. Bakharev E. L. Rosenfeld I. S. Rosovsky 《黑龙江环境通报》1983,3(3):233-236
Chorion biopsy specimens were used for prenatal assay of arylsulphatase A activity in a pregnant woman whose two children had died from metachromatic leukodystrophy (MLD). As in two subsequent pregnancies chorion arylsulphatase A was in the control range, it was concluded that both fetuses were healthy. Absence of MLD in the fetus from the first pregnancy was confirmed after assay of arylsuphatase A activity in fetal organs. The second pregnancy resulted in delivery of a healthy child. 相似文献
67.
High bat (Chiroptera) diversity in the Early Eocene of India 总被引:1,自引:0,他引:1
Smith T Rana RS Missiaen P Rose KD Sahni A Singh H Singh L 《Die Naturwissenschaften》2007,94(12):1003-1009
The geographic origin of bats is still unknown, and fossils of earliest bats are rare and poorly diversified, with, maybe,
the exception of Europe. The earliest bats are recorded from the Early Eocene of North America, Europe, North Africa and Australia
where they seem to appear suddenly and simultaneously. Until now, the oldest record in Asia was from the Middle Eocene. In
this paper, we report the discovery of the oldest bat fauna of Asia dating from the Early Eocene of the Cambay Formation at
Vastan Lignite Mine in Western India. The fossil taxa are described on the basis of well-preserved fragments of dentaries
and lower teeth. The fauna is highly diversified and is represented by seven species belonging to seven genera and at least
four families. Two genera and five species are new. Three species exhibit very primitive dental characters, whereas four others
indicate more advanced states. Unexpectedly, this fauna presents strong affinities with the European faunas from the French
Paris Basin and the German Messel locality. This could result from the limited fossil record of bats in Asia, but could also
suggest new palaeobiogeographic scenarios involving the relative position of India during the Early Eocene. 相似文献
68.
We conducted a laboratory evaluation to assess the risk to early life stage (i.e., eyed egg to swim up) fall Chinook salmon
(Oncorhynchus tshawytscha) for exposure to hexavalent chromium from a contaminated groundwater source. Local populations of fall Chinook salmon were
exposed to Hanford Site source groundwater that was diluted with Columbia River water. Specific endpoints included survival,
development rate, and growth. Tissue burdens of fish were also measured to estimate uptake and elimination rates of chromium.
Survival, development, and growth of early life stage fall Chinook salmon were not adversely affected by extended exposures
(i.e., 98 day) to hexavalent chromium ranging from 0.79 to 260 μg/l. Survival for all treatment levels and controls exceeded
98% at termination of the test. In addition, there were no differences among the mean lengths and weights of fish among all
treatment groups. Whole-body concentrations of chromium in early life stage fall Chinook salmon had a typical dose-response
pattern; i.e., those subjected to highest exposure concentrations and longest exposure intervals had higher tissue concentrations.
Given the spatial extent of chromium concentrations at the Hanford Site, and the dynamics of the groundwater–river water interface,
the current cleanup criterion of 10 μg/l chromium appear adequate to protect early life stage fall Chinook salmon. These findings,
together with previous research indicate low risk to these populations. 相似文献
69.
70.
对某铁路机务段420名一线职工进行心理健康状况的现况研究并探索其影响因素,初步建立心理健康风险评估模型。整群抽取420例样本,采用症状自评量表(SCL-90)进行心理健康水平测评,与全国常模比较,采用二分类Logistic心理健康风险预警模型进行回归分析。结果表明,铁路一线职工在躯体化、饮食睡眠情况、敌对、强迫症状方面的得分均高于全国常模。年龄、文化程度、现职工种、劳动班制、工龄等因素影响职工心理健康状况。进而提出应做好职工心理疏导工作,探索一线职工心理健康预警指标,实现风险识别关口前移,保障铁路运输安全。 相似文献