An aromatase inhibitor and tamoxifen decrease plasma levels of o,p-DDT and its metabolites in Nile tilapia (Oreochromis niloticus)     

Olga Leaos-Castaeda  Gerardo Gold-Bouchot  Glen Van Der Kraak  Andrea Lister  Victor Ceja-Moreno  Raul Sim-Alvarez 《Marine environmental research》2004,58(2-5):337

The objective of this study was to determine if tamoxifen or an aromatase inhibitor (4-hydroxyandrostenedione; 4-OHA) affected plasma concentrations of o,p^′-DDT and its metabolites, o,p^′-DDD and o,p^′-DDE, in mature tilapia. Male and female tilapia were injected 6 times intraperitoneally with o,p^′-DDT (40 mg/kg) alone or in combination with 4-OHA (2 mg/kg) over a 12 day period. An additional group of male fish was injected with tamoxifen (5 mg/kg) plus o,p^′-DDT. At the end of the treatment period, plasma samples were extracted and analyzed by GC/ECD. Females injected only with o,p^′-DDT had significantly higher levels of o,p^′-DDT compared with males. Interestingly, females and males treated concomitantly with o,p^′-DDT and 4-OHA or tamoxifen had significantly lower concentrations of plasma o,p^′-DDT (about 50%) compared with fish treated with only o,p^′-DDT. These initial results suggest that an interaction between endocrine-active compounds occurs in vivo in tilapia and may involve alterations in metabolism of o,p^′-DDT.  相似文献   

Year-round cooling and thermal stabilization of water-saturated soils under engineering structures     

Vladimir Moiseev  Nicolai Vasiliev  Tatyana Komarov  Olga Komarova 《寒旱区科学》2017,9(3):258-260

We consider the problem of year-round cooling of water-saturated soil to freezing temperatures in order to convert it into a state of permafrost.A new soil-cooling apparatus is proposed.The apparatus is to be made in modular form and connected to passive-active thermal piles (thermosyphons).The estimated capacity of one apparatus allows simultaneous use of up to 1,000 thermal piles for ground freezing.The apparatus is based on natural sources of energy:solar radiation and wind;and it can be used for soil freezing.This approach can prevent thawing of soft soils under railways and roads,as well as under buildings or structures,in an area of more than tens of hectares.The apparatus has no mechanical moving parts and can operate for a long time in stand-alone mode without staff involvement.  相似文献   

A search for unique objects in nearby galaxies     

Sergei Fabrika  Olga Sholukhova 《Astrophysics and Space Science》1995,226(2):229-244

A list of 171 stars in the galaxy M33 is presented. The stars could be considered as candidates for unique objects, such as SS 433, S Dor, P Cyg stars and possibly new kinds of peculiar objects. All these stars have been selected on the basis of the similarity to SS 433, free from interstellar absorption: OB star with strongH emission or with HeII 4686 and CIII, NIII 4630 - 4660 emission lines; a hot star inside a supernovae remnant or radio nebula. The variability of these stars has been used as an additional criterion of the selection. It is important to carry out spectral observations of the presented stars, which will allow us to select stars with intrinsicH emission.  相似文献   

Seasonal variations of water quality in a highly populated drainage basin,SE Brazil: water chemistry assessment and geochemical modeling approaches     

Eduardo Duarte Marques  Emmanoel V. Silva-Filho  Giovana V. C. Souza  Olga Venimar O. Gomes 《Environmental Earth Sciences》2016,75(24):1498

The São João Drainage Basin is a very important and strategic waterbody located in the Lagos Region, Rio de Janeiro State, one of the most popular tourist regions of Brazil. However, the fast economic and subsequent population growth in that region has created untreated wastes from several anthropogenic activities, which include the trace metals disposal into the surface waterbody. This study aims to relate the major ions and trace metals behavior during a 1-year sampling campaign and to provide information about the sources of chemical constituents and the factors that control their concentrations in the three main fluvial compartments of the drainage basin, including the Juturnaíba Reservoir which has a crucial role for water supply in the Lagos Region. The chemical data reveal that rainfall is the main factor responsible for the physicochemical parameters and the water dissolved constituent’s variations. The geological and anthropogenic factors which are the main sources of water constituents were assessed by the Inorganic Chemical Index. Those data corroborate the great influence of rainfall and reveal the importance of anthropogenic sources of chemical constituents in some parts of the Juturnaíba Reservoir. The geochemical modeling suggests that hydrolysis reactions are primarily responsible for the trace metals availability in the three fluvial compartments in both dry and wet seasons, followed by carbonate and sulfate complexation.  相似文献   

Delineation of riparian vegetation from Landsat multi‐temporal imagery using PCA          下载免费PDF全文

Masoomeh Alaibakhsh  Irina Emelyanova  Olga Barron  Neil Sims  Mehdi Khiadani  Alireza Mohyeddin 《水文研究》2017,31(4):800-810

A deficiency in crucial digital data, such as vegetation cover, in remote regions is a challenging issue for water management and planning, especially for areas undergoing rapid development, such as mining in the Pilbara, Western Australia. This is particularly relevant to riparian vegetation, which provides important ecological services and, as such, requires regional protection. The objective of this research was to develop an approach to riparian vegetation mapping at a regional scale using remotely sensed data. The proposed method was based on principal component analysis applied to multi‐temporal Normalized Difference Vegetation Index datasets derived from Landsat TM 5 imagery. To delimit the spatial extent of riparian vegetation, a thresholding method was required and various thresholding algorithms were tested. The accuracy of results was estimated for various Normalized Difference Vegetation Index multi‐temporal datasets using available ground‐truth data. The combination of a 14‐dry‐date dataset and Kittler's thresholding method provided the most accurate delineation of riparian vegetation.  相似文献   

Mammal fauna during the Late Pleistocene and Holocene in the far northeast of Europe     

Dmitry Ponomarev  Andrey Puzachenko  Olga Bachura  Pavel Kosintsev  Johannes van der Plicht 《Boreas: An International Journal of Quaternary Research》2013,42(3):779-797

The paper summarises materials on the mammal remains in northeastern Europe, dated by radiocarbon. Altogether, 23 local faunas of small mammals and 47 local faunas of large mammals were analysed. Multidimensional statistical analysis shows a strong correlation between changes in small mammal fauna composition and climate changes throughout time. The correlations with the spatial gradients, however, are less pronounced. The faunas are classified into three groups: (1) faunas of Holocene age; (2) Late Pleistocene ‘stadial’ assemblages; and (3) Late Pleistocene ‘interstadial’ assemblages. In some cases, changes in species abundance are better understood in terms of biotic interrelations rather than of climatic effects. The most pronounced change in small mammal fauna composition and structure occurred at the Preboreal/Boreal boundary, and a less conspicuous alteration took place at the LGM/Lateglacial transition. The most noticeable transformation in the large mammal fauna composition is dated to the early Holocene. Less significant changes are observed at the Middle Weichselian/LGM transition and at the LGM/Lateglacial transition. It is safely concluded that variations in the faunas of small and large mammals recorded in NE Europe during the last 35 000 years occurred synchronously and unidirectionally.  相似文献   

REE in fluid inclusions of quartz from gold deposits of north-eastern Russia     

Olga V. Vikent’eva  Gennady N. Gamyanin  Nikolay S. Bortnikov 《Central European Journal of Geosciences》2012,4(2):310-323

Inductively coupled plasma-mass spectrometry (ICP-MS) has been used to determine rare earth element concentrations in aqueous solutions extracted from fluid inclusions. Quartz has been sampled from ores of three major types of polygenic gold hydrothermal systems of North-Eastern Russia: (1) gold-quartz-sulphide (Au-Q, Nezhdaninsk); (2) gold-antimony (Au-Sb, Sarylakh) and (3) intrusion-related gold-bismuth-siderite-polysulphide (Au-Bi-Sid, Arkachan) large deposits located in terrigenous rocks of the Verkhoyansk fold belt. The total concentration of REE in the fluid inclusions is not high (up to 52 ppm). The contribution of LREE dominates in REE balance (??LREE/??HREE=7.4?C112.1). The chondrite-normalized REE patterns of inclusion fluids for the Au-Q and Au-Bi-Sid deposits are characterized by LREE enrichment with a positive or negative Eu anomaly. REE patterns for the regenerated quartz from Au-Sb deposits are characterized by pronounced differentiation between light and heavy lanthanides in fluid inclusions. Significant total REE concentration decreasing (on 1?C2 order) from early to late stages of Nezhdaninsk and Arkachan deposits is revealed. The positive correlations of total REE concentrations with Rb, Cs, Li and B contents in fluid inclusions are shown. The REE distribution in fluid inclusions can be used as indicators of the contribution of magmatic fluid in the hydrothermal system.  相似文献   

Modified Chaplygin gas and solvable F-essence cosmologies     

Mubasher Jamil  Yerlan Myrzakulov  Olga Razina  Ratbay Myrzakulov 《Astrophysics and Space Science》2011,336(2):315-325

The Modified Chaplygin Gas (MCG) model belongs to the class of a unified models of dark energy and dark matter. In this paper, we have modeled MCG in the framework of f-essence cosmology. By constructing an equation connecting the MCG and the f-essence, we solve it to obtain explicitly the pressure and energy density of MCG. As special cases, we obtain both positive and negative pressure solutions for suitable choices of free parameters. We also calculate the state parameter which describes the phantom crossing.  相似文献   

Effect of Ecological Factors on the Distribution of Microorganisms in Regosols (Steppe of Priol’khonie, Siberia)     

Olga LOPATOVSKAYA  Anna SEREDKINA  Natalia BELKOVA 《《地质学报》英文版》2014,88(Z1):188-190

正1 Introduction Regosol in Eastern Siberia is intrazonal soil.In Priolkhonie region it occurs among chestnut soils,salt marshes and solonetzes.There are small information about Tagotskij hydrolaccolith in the research articles of geologists,archaeologists,and paleolimnologists when  相似文献   

On the interface error analysis for finite difference wave simulation   总被引：1，自引：0，他引：1  

Vadim Lisitsa  Olga Podgornova  Vladimir Tcheverda 《Computational Geosciences》2010,14(4):769-778

A common way to construct a finite difference scheme is to satisfy a desired order of approximation, typically as high as possible. For linear wave propagation problem approximation together with stability delivers convergence of the same order as approximation. If a wave propagation proses is considered convergence to a plane wave solution can be derived analytically by means of the dispersion analysis. However, mentioned techniques are applicable only to homogeneous media and provide no knowledge of reflection/transmission coefficients. In this paper we prove that the only way to get second order accuracy of the solution for media with discontinuous parameters is to use a conservative finite difference scheme of the second order, and the only way to do this is to use the arithmetic mean for the density and the harmonic mean for the bulk modulus in the vicinity of the interface.  相似文献