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Abstract. Eupolymnia nebulosa (Terebellidae) and Hermodke carunculata (Amphinomidae) were compared with respect to rates of oxygen consumption in response to acute temperature and salinity variation. E. nebulosa , but not H. carunculata , demonstrated significant temperature sensitivity correlating with the former species' restriction to habitats that are temperature variation. In contrast, H. carunculata occurs where such fluctuation is common. Oxygen uptake in both species was responsive to dilution of the medium whereas only H. carunculata demonstrated insensitivity to increased salinity under most temperature conditions. 相似文献
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Abstract. The emergence of the Isthmus of Panama subdivided the amphi-American biota. In the present study, Pacific and Atlantic populations of four cognate pairs of crabs were used to discern whether exposure to different thermal regimes in habitats, in the putative absence of gene flow, has resulted in physiological divergence. Populations that potentially form a common genetic pool were also used; these were populations of the Atlantic Panama cognate that occur in Belize and Florida. Decreases in water temperature occur periodically in Pacific Panama and Florida, but not in Atlantic Panama or Belize. In this study, physiological divergence in oxygen uptake was assessed in response to repeated exposure to either control and decreased temperature or control and increased temperature. Results indicate that, in only some of the genera tested, exposure to decreases in habitat temperature has resulted in divergence. Partial support is found for the corollary that adaptation to an environment with periods of decreased temperature results in reduced compensation during exposure to elevated temperature. 相似文献
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Pyroxenes of pigeonitic and augitic bulk compositions in H3–4 chondritic meteorites commonly exhibit sigmoidal precipitates, rather than the elsewhere common lamellar associations. Most often, submicrometric sigmoids with calcic clinopyroxene composition occur within clinoenstatite; more rarely, clinoenstatite sigmoids occur within calcic clinopyroxene. The sigmoids appear as 001 terminated lamellae, with terminations rotated in opposite directions towards the 100 orientation. Pre-exsolution pigeonite and augite formed at temperatures higher than 980 °C, whereas sigmoidal exsolution occurred between 990 and 830 °C. Local anomalous lattice parameters determined by electron diffraction suggest that lattice parameters are most strained where the exsolution texture is most poorly defined. Shear strain occurs during exsolution due to mismatching lattice parameters and variable angles. In response to shear stress, the lamellae relax and assume sigmoidal strained morphologies. Sigmoidal exsolution is strongly controlled by (100) orthoenstatite stacking faults that possibly trigger exsolution. 相似文献
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本文的资料是国际矿物学协会新矿物及矿物命名委员会提供的,以资矿物学家在新矿物研究工作中参考和对比。ＣＮＭＭＮ鼓励其成员将本文提交其所在国家的有关刊物发表。中译文由中国新矿物及矿物命名委员会供稿。文中所列的已经批准的新矿物的名称及其详细资料,将由每个新... 相似文献
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本文资料是国际矿物学协会新矿物及矿物命名委员会提供的,以资矿物学家在新矿物研究工作中参考和对比.CNMMN鼓励其成员将本文其所在国家的有关刊物发表. 相似文献
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Verónica Oliveros Dania Tristá-Aguilera Gilbert Féraud Diego Morata Luis Aguirre Shoji Kojima Fernando Ferraris 《Mineralium Deposita》2008,43(1):61-78
The Michilla mining district comprises one of the most important stratabound and breccia-style copper deposits of the Coastal
Cordillera of northern Chile, hosted by the Middle Jurassic volcanic rocks of the La Negra Formation. 40Ar/39Ar analyses carried out on igneous and alteration minerals from volcanic and plutonic rocks in the district allow a chronological
sequence of several magmatic and alteration events of the district to be established. The first event was the extrusion of
a thick lava series of the La Negra Formation, dated at 159.9 ± 1.0 Ma (2σ) from the upper part of the series. A contemporaneous intrusion is dated at 159.6 ± 1.1 Ma, and later intrusive events are
dated at 145.5 ± 2.8 and 137.4 ± 1.1 Ma, respectively. Analyzed alteration minerals such as adularia, sericite, and actinolite
apparently give valid 40Ar/39Ar plateau and miniplateau ages. They indicate the occurrence of several alteration events at ca. 160–163, 154–157, 143–148,
and 135–137 Ma. The first alteration event, being partly contemporaneous with volcanic and plutonic rocks, was probably produced
in a high thermal gradient environment. The later events may be related either to a regional low-grade hydrothermal alteration/metamorphism
process or to plutonic intrusions. The Cu mineralization of the Michilla district is robustly bracketed between 163.6 ± 1.9
and 137.4 ± 1.1 Ma, corresponding to dating of actinolite coexisting with early-stage chalcocite and a postmineralization
barren dyke, respectively. More precisely, the association of small intrusives (a dated stock from the Michilla district)
with Cu mineralization in the region strongly suggests that the main Michilla ore deposit is related to a magmatic/hydrothermal
event that occurred between 157.4 ± 3.6 and 163.5 ± 1.9 Ma, contemporaneous or shortly after the extrusion of the volcanic
sequence. This age is in agreement with the Re–Os age of 159 ± 16 Ma obtained from the mineralization itself (Tristá-Aguilera
et al., Miner Depos, 41:99–105,2006). 相似文献
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A high pressure neutron powder diffraction study of portlandite [Ca(OH)2] has been performed at ISIS facility (U.K.); nine spectra have been collected increasing the pressure by steps, up to 10.9 GPa,
by means of a Paris-Edinburgh cell installed on the POLARIS diffractometer. The tensorial formalism of the lagrangian finite
strain theory and the Birch-Murnaghan equation of state have been used to determine, independently, two values of the bulk
modulus of portlandite, obtaining K
0=38.3(±1.1) GPa [linear incompressibilities: K
0a=188.4(±9.9), K
0c=64.5(±2.5) GPa] and K
0=34.2(±1.4) GPa, respectively. The present results comply with values from previous measurements by X-ray diffraction [K
0=37.8(±1.8) GPa] and Brillouin spectroscopy [K
0=31.7(±2.5) GPa]. Reasonably, Ca(OH)2 has revealed to be bulkly softer than Mg(OH)2 [K
0=41(±2), K
0a=313, K
0c=57 GPa]. The Ca(OH)2 linear incompressibility values reflect the nature of forces acting to stabilize the (001) layer structure and, further,
prove that the replacement Ca/Mg mainly affects the elastic properties in the (001) plane, rather than along the [001] direction.
Data from a full refinement of the structure at room pressure are reported.
Received January 12, 1996/Revised, accepted June 15, 1996 相似文献
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P. Laiolo S. Gabellani N. Rebora R. Rudari L. Ferraris S. Ratto H. Stevenin M. Cauduro 《水文研究》2014,28(9):3466-3481
Probabilistic hydrometeorological forecasting systems are becoming more and more an operational tool used by civil protection centres for issuing flood alerts. One of the most important requests of decision makers is related to the reliability of such systems and to the validation of their predictive performances. For these reasons, this work is devoted to the validation of a probabilistic flood forecasting system called Flood‐PRObabilistic Operational Forecasting System (Flood‐PROOFS). The system is operational in real time, since 2008, in Valle d'Aosta, an alpine Region of northern Italy. It is used by the Civil Protection regional service to issue warnings and by the local water company to protect its facilities. The system manages and uses both real‐time meteorological and satellite data and real‐time data on the operation of the control structures in dam and river, managed by the water company. It has proven a useful tool for flood forecasting and for managing complex situations, facilitating the dialogue between civil protection and the water company during crisis periods. The system uses both a limited area model forecast and a forecast issued by regional expert meteorologists. The main outputs are deterministic and probabilistic discharge forecasts in different outlet areas of the river network. The performance of the system has been evaluated on a 25 months period with different statistical methods such as Brier score and Rank histograms. The results highlight good performances of the system as support system for emitting warnings, but there is a lack of statistics especially for huge discharge events. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献