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111.
Artificial light at night: implications for early life stages development in four temperate freshwater fish species 总被引:1,自引:0,他引:1
Anika Brüning Franz Hölker Christian Wolter 《Aquatic Sciences - Research Across Boundaries》2011,73(1):143-152
Flora and fauna have both evolved under a natural cycle of light and dark. But especially in urban areas, the night is now
increasingly disturbed by artificial light. Many traits and behaviours in fish are triggered by a circadian clock, for example
hatching and swim bladder inflation, which predominantly take place at dusk or night. As lighting becomes brighter and extends
farther into rural areas, the distinction between day and night becomes increasingly blurred. Therefore, the loss of diurnal
trigger by artificial light at night was hypothesized having deleterious effects on these traits and impact fish reproduction.
To assess these effects, eggs of four native freshwater fishes, Eurasian perch Perca fluviatilis, roach Rutilus rutilus, bleak Alburnus alburnus and chub Leuciscus cephalus, were incubated under two different light conditions: a photoperiod of 14 h light:10 h darkness (LD) and continuous illumination
(LL). The time to hatch and swim bladder inflation was recorded. The species showed inconsistent reactions to the light treatments.
In roach and bleak, the time to 50% hatch was longer in LL, whereas continuous lighting had an accelerating effect in chub.
Incubation in LL elongated the hatching period in perch and roach and, in perch, the onset of darkness seemed to trigger hatching.
The swim bladder inflation was significantly promoted by continuous light in chub and bleak but was not affected in roach.
In conclusion, nocturnal artificial illumination could have an effect on hatching and initial swim bladder filling by masking
the day–night-change and thereby diminish the trigger effect. However, the reactions were species specific and the increase
in variation indicated a lack of diurnal triggering, whilst a general deleterious effect of artificial light at night has
not been identified on early life stages. 相似文献
112.
The location of galaxies in 377 rich Abell galaxy clusters is discussed. We compared the distributions of galaxies in the sample containing all galaxies with the sample compiled from the 20 brightest objects. Counts in circular sectors with angle width equal to 30î show isotropy. Only in the case of BM I clusters and the coordinate system related to the cluster major axis did we find anisotropic distributions. We investigated also the distributions of galaxy position angles within clusters exhibiting isotropy. The structure position angles for both samples have been studied as well. They appeared to be different. The difference in location of galaxies in the case of cD clusters, as well as the more elliptical shape and different position angles of samples containing bright galaxies is observed. 相似文献
113.
The spectrographs on-board the World Space Observatory (WSO) will provide access to the 1020–1800 Å wavelength range with unprecedented sensitivity. Previous observatories operating in the 1150–2000 Å range (such as IUE and HST-STIS) have proved extremely useful to study the winds of OB type stars, which leave their most prominent imprints in the far ultraviolet range. The addition of the λ < 1200 Å wavelengths is critical as it contains important diagnostic lines for mass loss and shocks in the wind, as found by FUSE-based analyses.WSO will enable quantitative spectroscopic analyses of blue massive stars in the Local Group beyond the Magellanic Clouds. The results will lead to the characterization of their winds as a function of metallicity, and shed new light on current urging questions regarding radiation driven winds. 相似文献
114.
Based on daily average temperatures and observation data from 74 meteorological stations in Chinese oases, we calculate five-day (pentad) average temperature ≤0°C for the start and end pentad as well as pentads of cold period using linear regression analysis, nonparametric Mann-Kendall tests, the Morlet wavelet power spectrum, and correlation analysis. We also analyze spatial and temporal variations and their effects on the start and end pentad as well as pentads of cold period in Chinese oases. Results show that over the last 55 years, the start pentad of cold period has been postponed while the end pentad has been advanced. Overall, the pentads have gradually shortened over time at trend rates that are 0.3 p/10a,–0.27 p/10a, and–0.58 p/10a, respectively. Spatial differences are significant, especially for the Qaidam Basin oasis where the start pentad is the earliest, the end pentad is the latest, and the trend of change is most obvious. Mutation points for the start and end pentad as well as pentads of cold period were observed in 1990, 1998, and 1994, respectively. Of these, the start pentad and pentads of cold period show a periodic cycle, related to atmospheric circulation and El Nino events, while the end pentad exhibits a periodic cycle, related to solar activity. The Tibetan Plateau index (TPI), the Asian polar vortex area index (APVAI), and carbon dioxide emissions (CDE) are the main factors affecting cold period in the study area, whereas the South Asian summer monsoon (SASM) index exerts the greatest effect on the Qaidam Basin oasis. The start and end pentad as well as pentads of cold period increase in concert with latitude, longitude, and altitude; in response to these changes, the start pentad is advanced, the end pentad is postponed, and pentads of cold period are gradually extended. Results show that change in latitude is most significant. Overall, the start and end pentad as well as pentads of cold period show clear responses to regional warming, but there are different effects on each. 相似文献
115.
Theoretical difficulties for mapping and for estimating river regime characteristics in a large-scale basin remain because of the nature of the variable under study: river flows are related to a specific area, i.e. the drainage basin, and are hierarchically organized in space through the river network with upstream-downstream dependencies. Another limitation is there are not enough gauge stations in developing countries. This presentation aims at de-veloping the hydro-stochastic approach for producing choropleth maps of average annual runoff and computing mean discharge along the main river network for a large-scale basin. The approach applied to mean annual runoff is based on geostatistical interpolation proce-dures coupled with water balance and data uncertainty analyses. It is proved by an applica-tion in the upstream at Bengbu in the Huaihe River Basin, a typical large-scale basin in China. Hydro-stochasitic approach in a first step interpolates to a regular grid net and in a second step the grid values are integrated along rivers. The interpolation scheme includes a con-straint to be able to account for the lateral water balance along the rivers. Grid runoff map with 10 km × 10 km resolution and the discharge map along the river with the 1 km basic length unit are the main results in this study. This kind of statistic approach can be widely used be-cause it avoids the complexity of hydrological models and does not depend on the meteoro-logical data. 相似文献
116.
Protease is wildly used in various fields, such as food, medicine, washing, leather, cosmetics and other industrial fields. In this study, an alkaline protease secreted by Micrococcus NH54PC02 isolated from the South China Sea was purified and characterized. The growth curve and enzyme activity curve indicated that the cell reached a maximum concentration at the 30th hour and the enzyme activity reached the maximum value at the 36th hour. The protease was purified with 3 steps involving ammonium sulfate precipitation, ion-exchange chromatography and hydrophobic chromatography with 8.22-fold increase in specific activity and 23.68% increase in the recovery. The molecular mass of the protease was estimated to be 25 kDa by SDS-PAGE analysis. The optimum temperature and pH for the protease activity were 50°C and pH 10.0, respectively. The protease showed a strong stability in a wide range of pH values ranging from 6.0–11.0, and maintained 90% enzyme activity in strong alkaline environment with pH 11.0. Inhibitor trials indicated that the protease might be serine protease. But it also possessed the characteristic of metalloprotease as it could be strongly inhibited by EDTA and strongly stimulated by Mn2+. Evaluation of matrix-assisted laser desorption ionization/time-of-flight MS (MALDI-TOF-TOF/MS) showed that the protease might belong to the peptidase S8 family. 相似文献
117.
R. Pandiyan S. V. Subbarao T. Nagamani Chaitra Rao N. Hari Prasad Rao Harish Joglekar Naresh Kumar Surya Ratna Prakash Dumpa Anshu Chauhan B. P. Dakshayani 《Journal of Astrophysics and Astronomy》2017,38(2):35
On 28th September 2015, India launched its first astronomical space observatory AstroSat, successfully. AstroSat carried five astronomy payloads, namely, (i) Cadmium Zinc Telluride Imager (CZTI), (ii) Large Area X-ray Proportional Counter (LAXPC), (iii) Soft X-ray Telescope (SXT), (iv) Ultra Violet Imaging Telescope (UVIT) and (v) Scanning Sky Monitor (SSM) and therefore, has the capability to observe celestial objects in multi-wavelength. Four of the payloads are co-aligned along the positive roll axis of the spacecraft and the remaining one is placed along the positive yaw axis direction. All the payloads are sensitive to bright objects and specifically, require avoiding bright Sun within a safe zone of their bore axes in orbit. Further, there are other operational constraints both from spacecraft side and payloads side which are to be strictly enforced during operations. Even on-orbit spacecraft manoeuvres are constrained to about two of the axes in order to avoid bright Sun within this safe zone and a special constrained manoeuvre is exercised during manoeuvres. The planning and scheduling of the payloads during the Performance Verification (PV) phase was carried out in semi-autonomous/manual mode and a complete automation is exercised for normal phase/Guaranteed Time Observation (GuTO) operations. The process is found to be labour intensive and several operational software tools, encompassing spacecraft sub-systems, on-orbit, domain and environmental constraints, were built-in and interacted with the scheduling tool for appropriate decision-making and science scheduling. The procedural details of the complex scheduling of a multi-wavelength astronomy space observatory and their working in PV phase and in normal/GuTO phases are presented in this paper. 相似文献
118.
Soil sediment samples of 10 layers with a spacing of 10 cm each were collected in different floodplain zones adjacent to Huolin
River in the Xianghai Nature Reserve, and contents of total N, total P and organic matters were analyzed. The results showed
that contents of total N, total P and organic matters were generally decreasing with the increase of distance from sample
locations to the river channel, and contents of the three items were generally higher in the upper soil layer than that in
the lower soil layer. The content variations displayed how flooding functions influenced nutrient matter content variations
in floodplain soils since the flood inundation frequencies of the sample locations varied. The correlation analysis displayed
that there were remarkable relativities between total N, total P and organic matters within definite spatial distance from
the Huolin River channel. 相似文献
119.
Potential promoted productivity and spatial patterns of medium- and low-yield cropland land in China 总被引:1,自引:1,他引:1
With a continuously increasing population and better food consumption levels, improving the efficiency of arable land use and increasing its productivity have become fundamental strategies to meet the growing food security needs in China. A spatial distribution map of medium- and low-yield cropland is necessary to implement plans for cropland improvement. In this study, we developed a new method to identify high-, medium-, and low-yield cropland from Moderate Resolution Imaging Spectroradiometer (MODIS) data at a spatial resolution of 500 m. The method could be used to reflect the regional heterogeneity of cropland productivity because the classification standard was based on the regionalization of cropping systems in China. The results showed that the proportion of high-, medium-, and low-yield cropland in China was 21%, 39%, and 40%, respectively. About 75% of the low-yield cropland was located in hilly and mountainous areas, and about 53% of the high-yield cropland was located in plain areas. The five provinces with the largest area of high-yield cropland were all located in the Huang-Huai-Hai region, and the area amounted to 42% of the national high-yield cropland area. Meanwhile, the proportion of high-yield cropland was lower than 15% in Heilongjiang, Sichuan, and Inner Mongolia, which had the largest area allocated to cropland in China. If all the medium-yield cropland could be improved to the productive level of high-yield cropland and the low-yield cropland could be improved to the level of medium-yield cropland, the total productivity of the land would increase 19% and 24%, respectively. 相似文献
120.
The accumulation of sediment in river channels is a phenomenon that is not only influenced by the channel morphology, but also by the physical and geographical characteristics and the endogenous and exogenous processes taking place in the catchment. This paper presents an analysis of the impact the changes in lithological conditions have on the morphological and morphometric parameters of the Udava River channel and their relation to the channel accumulation forms representative of the river’s longitudinal profile as well as of its planform. Results document when accumulation forms occur and what is their spatial distribution within the longitudinal and cross-sectional river profiles. More resistant structures created sections with a lower degree of sedimentation, while in depression segments the degree of sedimentation was higher. With the increase in longitudinal slope, the impact of channel width on the average channel bar size increased. Also a difference in the accumulation was observed between the left and right bank which could be possibly explained by the impact of Coriolis force. 相似文献