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911.
Specimens of either sex of the freshwater catfish Mystus vittatus were exposed to an acute toxic dose of an agro-chemical NPK, i.e. 550 ppm during the spawning phase of their annual reproductive cycle. The effects on total lipid and its various fractions, viz. phospholipids and cholesterol, were studied in the testes and ovary. The total lipid content of the gonads of unstressed fish showed lowest values during the spawning phase when compared to other phases, the content remained higher in the ovary than in the testes. In fish subjected to NPK-stress during the spawning period, the fall in total lipid content of the gonads was found to be much greater than that in the controls. The phospholipids content of the gonads of unstressed fish showed highest values during the spawning phase when compared to other phases; the content remained higher in the ovary than in the testes. In fish subjected to NPK-stress during the spawning phase the rise in the gonads was found to be higher than that in the control. The cholesterol content of the gonads of unstressed fish showed highest values during the spawning phase when compared to other phases; the content remained higher in the ovary than in the testes. In fish subjected to NPK-stress during the spawning period the rise in the cholesterol content of the gonads was not found to be as high as that in the controls. Agro-chemical NPK seemed to effect the total lipid and cholesterol content adversely during the spawning phase, affecting the vitellogenic process without affecting the biosynthesis of phospholipids as such, which on the contrary increases. The decrease of lipid and cholesterol mobilization from liver to gonads seemed to be restricted as a result of NPK action. 相似文献
912.
This study compares the thermal bioclimatic conditions recorded at Bursa (100 m) and Uluda? (1878 m) meteorological stations at 7:00, 14:00 and 21:00 LST (local standard time) between 1975 and 2006, by using the physiologically equivalent temperature (PET), which is calculated from meteorological parameters. The effects of elevation-dependent environmental and atmospheric conditions on thermal perception (i.e., PET) values were analyzed and assessed. The analysis showed that the mean annual difference between PET values in Bursa and Uluda? was 12 ºC. The difference was lower in winter (9 ºC PET) and higher in summer (15 ºC PET). The highest difference between PET values occurred in the afternoon (16 ºC PET) and the lowest difference occurred in the morning (8.4 ºC PET). The differences occur as a result of high altitude and higher surface albedo due to snowfall, which leads to lower PET values and thus to less comfortable thermal conditions. The mean PET values of Bursa and Uluda? decrease 0.67 ºC every 100 m. 相似文献
913.
Two types of tectonic deformations indicating different geodynamic settings are defined in the southwestern Primorye region. Near-latitudinal compression forces were responsible for the oldest, Late Paleozoic deformations. The Permian stratified complexes host a near-meridional system of folds and zones of dynamothermal metamorphism, cleavage, and foliation oriented orthogonally relative to the compression. Late Proterozoic (?) mafic-ultramafic rocks are characterized by similar deformations. In the Late Permian, the deformations were accompanied by granitoid magmatism controlled by fold and cleavage structures. The younger, Mesozoic deformations produced by near-meridional compression are represented by NE-trending sinistral strike-slip faults and their structural parageneses: an ENE-trending system of folds and downdip-thrusts both superimposed on Paleozoic protostructures and manifested in Mesozoic and Cenozoic sequences. It is inferred that, at the Paleozoic-Mesozoic boundary, near-latitudinal compression was replaced by near-meridional compression, probably, in response to the corresponding change in direction of the lateral displacement of the interacting Asian continent and (or) Pacific Plate. 相似文献
914.
E.?F.?MikhailovEmail author S.?Yu.?Mironova M.?V.?Makarova S.?S.?Vlasenko T.?I.?Ryshkevich A.?V.?Panov M.?O.?Andreae 《Izvestiya Atmospheric and Oceanic Physics》2015,51(4):423-430
The results of 2-year (2010–2012) measurements of the concentrations of organic carbon (OC) and elemental carbon (EC), which were taken at the Zotino Tall Tower Observatory (ZOTTO) Siberian background station (61° N, 89° E), are given. Despite the fact that this station is located far from populated areas and industrial zones, the concentrations of OC and EC in the atmosphere over boreal forests in central Siberia significantly exceed their background values. In winter and fall, high concentrations of atmospheric carbonaceous aerosol particles are caused by the long-range transport (~1000 km) of air masses that accumulate pollutants from large cities located in both southern and southwestern regions of Siberia. In spring and summer, the pollution level is also high due to regional forest fires and agricultural burning in the steppe zone of western Siberia in the Russian–Kazakh border region. Background concentrations of carbonaceous aerosol particles were observed within relatively short time intervals whose total duration was no more than 20% of the entire observation period. In summer, variations in the background concentrations of OC closely correlated with air temperature, which implies that the biogenic sources of organic-particle formation are dominating. 相似文献
915.
Identifying the precursors (pre-increases or pre-decreases) of a geomagnetic storm or a Forbush decrease is of great importance since they can forecast and warn of oncoming space weather effects. A wide investigation using 93 events which occurred in the period from 1967 to 2006 with an anisotropy A xy >1.2% has been conducted. Twenty-seven of the events revealed clear signs of precursors and were classified into three categories. Here we present one of the aforementioned groups, including five Forbush decreases (24 June 1980, 28 October 2000, 17 August 2001, 23 April 2002, and 10 May 2002). Apart from hourly cosmic ray intensity data, provided by the worldwide network of neutron monitor stations, data on solar flares, solar wind speed, geomagnetic indices (Kp and Dst), and interplanetary magnetic field were used for the analysis of the examined cosmic ray intensity decreases. The asymptotic longitudinal cosmic ray distribution diagrams were plotted using the “ring of stations” method. Results reveal a long pre-decrease up to 24 hours before the shock arrival in a narrow longitudinal zone from 90° to 180°. 相似文献
916.
The global distribution of solar surface activity (active regions) is apparently connected with processes in the convection
zone. The large-scale magnetic structures above the tachocline could in a pronounced way be observable in the surface magnetic
field. To get the information regarding large-scale magnetic formations in the convection zone, a set of solar synoptic charts
(Mount Wilson 1998 – 2004, Fe i, 525.02 nm) have been analyzed. It is shown that the longitudinal dimensions and dynamics of supergiant complexes of solar
surface activity carry valuable information about the processes in the convection zone of the Sun. A clear effect of large-scale
(global) turbulence is found. This is a ‘fingerprint’ of deep convection, because there are no such large-scale turbulent
eddies in the solar photosphere. The preferred scales of longitudinal variations in surface solar activity are revealed. These
are: ∼ 24° (gigantic convection cells), 90°, 180° and 360°. 相似文献
917.
Application of boundary value techniques in the case of an electron performing relativistic motions within a magnetic dipole such as that of the Earth supplemented by a scanning process by means of which the entire phase space of the problem can be investigated, six new types of periodic motion have been discovered and computed. The stability of these motions is investigated and their direct bearing on formation and shape of the Van Allen zones of the Earth is discussed. 相似文献
918.
The October 1976 spectroscopic observations of the solar chromosphere with the great coronagraph of the Kislovodsk Station of the Pulkovo Observatory were analysed using the autocorrelation method. The autocorrelation function and the power spectrum were calculated. It was found that the brightness distribution in the chromosphere is essentially bimodal and has characteristic scales of 1.2 × 104 km and 2.4 × 104 km. The supergranulation (3.5 × 104 km) in the brightness field was found to show up more faintly at all heights. 相似文献
919.
In this paper we discuss the initial phase of chromospheric evaporation during a solar flare observed with instruments on the Solar Maximum Mission on May 21, 1980 at 20:53 UT. Images of the flaring region taken with the Hard X-Ray Imaging Spectrometer in the energy bands from 3.5 to 8 keV and from 16 to 30 keV show that early in the event both the soft and hard X-ray emissions are localized near the footpoints, while they are weaker from the rest of the flaring loop system. This implies that there is no evidence for heating taking place at the top of the loops, but energy is deposited mainly at their base. The spectral analysis of the soft X-ray emission detected with the Bent Crystal Spectrometer evidences an initial phase of the flare, before the impulsive increase in hard X-ray emission, during which most of the thermal plasma at 107 K was moving toward the observer with a mean velocity of about 80 km s-1. At this time the plasma was highly turbulent. In a second phase, in coincidence with the impulsive rise in hard X-ray emission during the major burst, high-velocity (370 km s-1) upward motions were observed. At this time, soft X-rays were still predominantly emitted near the loop footpoints. The energy deposition in the chromosphere by electrons accelerated in the flare region to energies above 25 keV, at the onset of the high-velocity upflows, was of the order of 4 × 1010 erg s-1 cm-2. These observations provide further support for interpreting the plasma upflows as the mechanism responsible for the formation of the soft X-ray flare, identified with chromospheric evaporation. Early in the flare soft X-rays are mainly from evaporating material close to the footpoints, while the magnetically confined coronal region is at lower density. The site where upflows originate is identified with the base of the loop system. Moreover, we can conclude that evaporation occurred in two regimes: an initial slow evaporation, observed as a motion of most of the thermal plasma, followed by a high-speed evaporation lasting as long as the soft X-ray emission of the flare was increasing, that is as long as plasma accumulation was observed in corona. 相似文献
920.
Repeated high quality geodetic observations allow the estimation of the free surface velocity field for a region. Usually, a yearly secular rate is estimated, while the possible episodic motion (seismic slip) due to an earthquake is evaluated via inversion of the geodetic data. The episodic motion influence is subtracted from the total field. The actual region and the respective geodetic observations affected by the seismic event are often assessed by rather vague criteria.This paper deals with an attempt to estimate simultaneously the secular and the episodic two-dimensional crustal motion for a region by means of repeated GPS observations of a geodetic network, carried out for a number of epochs.The model is applied to the Gulf of Corinth available GPS data, spanning a time interval of more than a decade, and the results are discussed. 相似文献