Reproductive ecology of the seabob shrimp <Emphasis Type="Italic">Xiphopenaeus kroyeri</Emphasis> (Heller, 1862) in a coastal area of Southern Brazil     

Raphael Cezar Grabowski  Maria Lucia Negreiros-Fransozo  Antonio Leão Castilho 《中国海洋湖沼学报》2016,34(1):125-135

The predictability of certain environmental factors that affect the life cycle of the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) was evaluated in a study of its reproductive biology in an area adjacent to Babitonga Bay, State of Santa Catarina, Brazil. Monthly sampling was conducted from July 2010 through June 2011 at depths of 5, 8, 11, 14, and 17 m. 76 004 individuals were obtained, with a pronounced peak in absolute abundance in austral autumn (34 208), coinciding with the annual closed season from March to May. Grain size composition of the sediment showed the closest relationship to the distribution of individuals (multiple linear regression, P <0.05), related to their burying habit. The observed correlations between the abundance of reproductive males (bearing spermatophores) and females with spent gonads (cross-correlation, P <0.05), and between reproductive males and reproductive females (with a 1-month lag) suggest that the peak of reproductive males preceded the peak of female ones. This result agrees with the pattern expected for females, which copulate in post-ecdysis (spent gonads). Spawning seemed to take place at greater depths, as evidenced by the concentration of reproductive females in these areas. The reproductive activities observed here confirm that this species follows a tropical/subtropical reproductive pattern, spawning continuously throughout the year, with the highest peaks in spring and autumn. The data indicate that the juvenile recruitment period observed in August-September resulted from the reproductive output noted in April–May. Additionally, the reproductive period recorded in November led to the juvenile peak observed in March–May.  相似文献   

Cross-axis sensitivity of accelerographs with pendulum like transducers—mathematical model and the inverse problem     

Maria I. Todorovska 《地震工程与结构动力学》1998,27(10):1031-1051

A mathematical model for a three-component accelerograph is presented that accounts for the effects of transducer misalignment and cross-axis sensitivity. The former refers to departures in the alignment of the transducer penduli (typically of the order of few degrees) from an ideal orthogonal system, and the latter to a transducer recording components of motion in directions other than its principal sensitivity axis. Transducer misalignment magnifies the effects of cross-axis sensitivity. These effects are significant only for large amplitude recordings (peak acceleration close to 1g), for example in the near-field of the 1994 Northridge, California, earthquake. The misalignment angles and the angular amplification constant can be determined by a static tilt test, performed in the field, and solving a generalized inverse problem. This paper presents an algorithm for solution of this inverse problem on a routine basis. Practical implementation of the algorithm and results for 76 instruments of the Los Angeles Strong Motion Array are presented in a separate paper. © 1998 John Wiley & Sons, Ltd.  相似文献   

Advanced sensitivity calibration of the Los Angeles strong motion array     

Maria I. Todorovska  Elena I. Novikova  Mihailo D. Trifunac  Sanja S. Ivanovi&#x; 《地震工程与结构动力学》1998,27(10):1053-1068

Results are presented of recent sensitivity calibration of 76 accelerographs (SMA-1) of the Los Angeles Strong Motion Array. These have pendulum-like transducers and optical recording system. One characteristic of their design is off-axis sensitivity, which is magnified by transducer misalignment. A new calibration procedure was applied, which considers off-axis sensitivity and measures the angles of misalignment (φ and ψ), as well as the incident angle of the light beam onto the film (θ₀). These are required (1) for accurate estimation of sensitivity, and (2) for proper instrument correction of recorded accelerograms which considers also cross-axis sensitivity and misalignment. These effects are important near large acceleration peaks (approaching and exceeding 1g), e.g. like the ones recorded near the source of the 1994 Northridge earthquake (M_L=6·4). This earthquake was recorded by 65 stations of the Los Angeles Strong Motion Array, at epicentral distances from 2 to 85 km. Histograms showing distribution of the misalignment angles, light beam incidence angle θ₀ (for unloaded position) and the transducer sensitivities are presented. These indicate that the misalignment angles are typically 1–1·5°, but may also be 3–4°. Angle θ₀ (usually neglected), is mostly between ±8°, but may reach ±12°. Assuming θ₀=0 leads to systematically smaller values of the measured sensitivity (e.g. by ∼3% for θ₀=8° and ∼4% for θ₀=12°). Comparison of the newly measured sensitivities with those measured prior to installation (in 1979/1980), s^old, shows that, in general, the new values are systematically smaller. The difference is typically within 5 per cent, but in some cases is as large as 10 per cent. Other principal sources of the observed differences and their mechanisms are discussed. Those include long-term changes in the transducers (e.g. change of stiffness, reflected in changes of the natural frequency) and differences in the calibration procedure (e.g. errors associated with manual reading film records with tilt test data, and with transducer and instrument housing misalignment). The presented results may be considered typical of similar strong motion arrays worldwide. © 1998 John Wiley & Sons, Ltd.  相似文献   

Development of a drought vulnerability index using MCDM and GIS: study case in São Paulo and Ceará, Brazil     

de Azevedo Reis  Gabriela  de Souza Filho  Francisco Assis  Nelson  Donald Robert  Rocha  Renan Vieira  da Silva  Samiria Maria Oliveira 《Natural Hazards》2020,104(2):1781-1799

Natural Hazards - Although climate change vulnerability research in general has increased over the last decade, Latin American countries have more directed more limited efforts toward vulnerability...  相似文献   

An evaluation of the performance of rock fall protection measures and their role in hazard zoning     

Jaccard  Camille-Jean  Abbruzzese  Jacopo Maria  Howald  Erika Prina 《Natural Hazards》2020,100(1):459-459

Natural Hazards - Rock falls threaten human lives and assets in mountainous regions all over the world. Protection measures are one of the most effective solutions for mitigating rock fall-related...  相似文献   

Analyzing the occurrence of floods and droughts in connection with climate change in Punjab province,Pakistan     

Ali  Syeda Maria  Khalid  Bushra  Akhter  Asma  Islam  Aneeza  Adnan  Shahzada 《Natural Hazards》2020,103(2):2533-2559

Natural Hazards - Frequency and intensity of extreme weather events are immensely changing throughout the world. This study aims to give insight into the changing climatic patterns leading to...  相似文献   

Mitigation of the seismic motion near the edge of cliff-type topographies using anchors and piles     

Constantine A. Stamatopoulos  Maria Bassanou 《Bulletin of Earthquake Engineering》2009,7(1):221-253

Concentration of damage of buildings near the edge of cliff-type topographies has been observed during a number of recent earthquakes and interpreted by numerical dynamic analyses that illustrate the amplification of the horizontal acceleration and the generation of parasitic vertical acceleration near the tip of slopes. The paper performs a detailed parametric numerical analysis to investigate the ability of mitigating this topographic effect using anchors and piles. A typical field case, the Aegion slope of Greece, is considered. Different input motions are applied. The results illustrated that anchors and piles can be effective in mitigating the topographic effect. The main issue is that if the part of the slope in which topographic amplification occurs is connected to that at larger depths, in which the acceleration is smaller, then the accelerations at the top of the slope have to become more uniform and smaller. For typical diameter and material properties of anchors/piles the effectiveness of the mitigation depends on the length, inclination, location and number of anchors/piles. An optimum configuration of anchors/piles mitigating the topographic effect is proposed.  相似文献   

Quantifying deforestation and secondary forest determinants for different spatial extents in an Amazonian colonization frontier (Rondonia)     

Luciana de Souza Soler  Maria Isabel S. Escada  Peter H. Verburg 《Applied geography (Sevenoaks, England)》2009,29(2):182-193

Spatial patterns of deforested areas and secondary forest are analyzed in terms of the spatial variation in location factors at different spatial extents. The spatial extents considered are old and new agrarian colonization projects and the administrative units of two different municipalities in Rondonia: Vale do Anari and Machadinho d'Oeste. A grid database was constructed including land cover and potential location factors based on biophysical, accessibility, socioeconomic and policy data. Results of the spatial analyses confirmed the hypothesis that different extents yield different relationships between land use/cover patterns and their location factors, particularly between old and new agrarian colonization projects. It emphasizes that current patterns of forest, secondary forest and pasture/agriculture can only be understood with a combination of policy, accessibility, biophysical and socioeconomic factors while accounting for the historical pathways of change. Because we are dealing with different trajectories of land use/cover change, static analysis of the spatial pattern without acknowledging these trajectories will lead to erroneous interpretations of the current and future land use/cover dynamics.  相似文献   

Photostability and photolability of dissolved organic matter upon irradiation of natural water samples under simulated sunlight   总被引：2，自引：0，他引：2  

Davide Vione  Vittorio Lauri  Claudio Minero  Valter Maurino  Mery Malandrino  Maria Eugenia Carlotti  Romeo-Iulian Olariu  Cecilia Arsene 《Aquatic Sciences - Research Across Boundaries》2009,71(1):34-45

  相似文献   

Shear and dilatational wave velocities for unsaturated soils     

Enrico Conte  Renato Maria CosentiniAntonello Troncone 《Soil Dynamics and Earthquake Engineering》2009

The primary objective of this study is for presenting some simple-to-use expressions relating the shear and dilatational wave velocities (V_S and V_P) to some physical and constitutive parameters of unsaturated soils. To this purpose, a simplified formulation is developed using the theory of linear poroelasticity in conjunction with some constitutive parameters widely used in geotechnical engineering. The derived expressions are of practical interest in view of the fact that they could be employed for evaluating the involved soil parameters from V_S and V_P measurements by in-situ or laboratory geophysical tests.  相似文献