22 resultados para threat


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The Zhikong Scallop, Chlamys farreri, is one of the most Important bivalve mollusks cultured in northern China However, mass mortality of the cultured C farreri has posed a serious threat to the maricultural Industry in recent years. Acute Viral Necrobiotic Virus (AVNV) is believed as an important etiological agent causing the scallop mass mortalities To understand the mechanism behind the AVNV associated scallop disease and mortality, we assessed the physiological and immune responses of C farreri to the virus infection using oxygen consumption rate, ammonium-nitrogen excretion rate, hemocyte copper, zinc superoxide dismutase gene expression, and plasma superoxide dismutase activity and alkaline phosphatase activity as indicators Scallops challenged by AVNV at 25 C developed typical disease signs 2 days after virus injection Before the disease manifested, scallop oxygen consumption and NH4+-N excretion rates rose and then fell back. Real-time PCR revealed that the hemocyte cytosol Cu, Zn SOD gene expression was upregulated followed by recovery The plasma SOD activity, however, augmented consistently following virus injection Moreover, plasma AKP activity first lowered and then elevated gradually to the highest level at 24 h post virus injection Scallops challenged by AVNV at 17 degrees C neither developed notable disease nor showed obvious responses that could be associated with the virus infection. While the results suggested a correlation between the elevated seawater temperature and the AVNV infection associated C farreri mortalities, they also indicated that the viral infection provoked multiple physiological and immune responses in the host scallops (C) 2010 Elsevier Ltd All rights reserved

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The recovery and fate of three species of dinoflagellates, Alexandrium tamarense, Cochlodinium polykrikoides and Scrippsiella trochoidea, after having been sedimented by yellow clay, were investigated in the laboratory. The effect of burying period in yellow clay pellet and mixing on the recovery of settled algal cells were studied. The morphological changes of algal cells in yellow clay pellet were also tracked. Results showed that there was almost no recovery for A. tamarense and C. polykrikoides, and the cells decomposed after 2-3 days after visible changes in morphology and chloroplasts. There was some recovery for S. trochoidea. Moreover, S. trochoidea cysts were formed in clay pellet during the period of about 14 days, with the highest abundance of 87 000 cysts g(-1) clay and the incidence of cyst formation of 6.5%, which was considered as a potential threat for the further occurrence of algal blooms. S. trochoidea cysts were isolated from yellow clay and incubated to test their viability, and a germination ratio of more than 30% was obtained after incubation for 1 month. These results showed the species specificity of the mitigation effect of yellow clay. It is suggested that cautions be taken for some harmful species and thorough risk assessments be conducted before using this mitigation strategy in the field.

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The specific activity concentrations of radionuclides U-238, Th-212, and K-40 of 2300 sampling points in the Qingdao area were measured by an FD-3022 gamma-ray spectrometer. The radioactivity concentrations of U-238, Th-232, and K-40 ranged from 3.3 to 185.3, from 6.9 to 157.2, and from 15.8 to 7834.4 Bq kg(-1), respectively. The air-absorbed dose at I meter above ground, effective annual dose, external hazard index, and radium equivalent activity were also calculated to systematically evaluate the radiological hazards of the natural radioactivity in Qingdao. The air-absorbed dose, effective annual dose, external hazard index, and radium equivalent activity in the study area were 98.6 nGy h(-1), 0.12 mSv, 0.56, 197 Bq kg(-1), respectively. Compared with the worldwide value, the air-absorbed dose is slightly high, but the other factors are all lower than the recommended value. The natural external exposure will not pose significant radiological threat to the population. In conclusion, the Qingdao area is safe with regard to the radiological level and suitable for living.

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China’s annual oil import volume has been increasing in recent years, but the oil price in the international market fluctuates and poses a severe threat to China’s economic development and national security. Therefore, it is of great importance to study the gas and oil exploration of Pre-Cenozoic Residual Basins in Yellow Sea. Yellow Sea has widespread and thick Mesozoic and Paleozoic strata that contain multilayer source rock. Hence, Yellow Sea Mesozoic and Paleozoic strata have good conditions of forming Pre-Cenozoic hydrocarbon reservoirs. Pre-Cenozoic Residual Basins are usually buried deep and then transformed many times in its long evolutional history. These characteristics make it difficult to apply a single method in exploring Pre-Cenozoic Residual Basins. On the other hand, it is highly effective to solve key problems of gas and oil exploration of Pre-Cenozoic Residual Basins in Yellow Sea by using integrated geological and geophysical methods which make full use of the advantages of various exploring techniques. Based on the principle of “the region controls the local; the deep restricts the shallow,” this study focuses on Pre-Cenozoic Residual Basins in Yellow Sea to describe the structure frame of its distribution, with gravity, magnetic, seismic, drill-hole and geological data and previous research findings. In addition, the distribution characteristics of Pre-Cenozoic Residual Basins in Yellow Sea are also analyzed. This paper explores the characteristics of error between gravity forward with constant density and gravity forward with variable density through the study on 2-D and 3-D gravity forward in frequency domain. The result shows that there is a linear relationship between error and depth of 2-D geological model but there is a nonlinear relationship between error and depth of 3-D geological model. The error can be removed according to its linear characteristics or statistical nature of nonlinear characteristics. There is also error between gravity inversion with constant density and gravity inversion with variable density due to variable density and edge-effect. Since there are not noticeable rules between the error and the two causes as variable density and edge-effect, this study adopts gravity inversion with variable density and methods to eliminate the edge-effect in basement inversion to improve inversion accuracy. Based on the study on the rock physical properties and strata distribution of Yellow Sea and adjacent regions, this study finds that there is a big density contrast between Cretaceous-Jurassic strata and their substratum. The magnetic basement of south Yellow Sea is regarded as top of Archeozoic-Proterozoic early strata, and there are double magnetic basements in north Yellow Sea. Gravity and magnetic data are used to inverse the gravity basement and magnetic basement of Yellow Sea, with seismic and drill-hole data as constrains. According to data of gravity and magnetic basement distribution, the depth of Cenozoic strata and previous research findings, this paper calculates the thickness of the Mesozoic and Pre-Mesozoic Residual Basins, draws the distribution outline of Pre-Cenozoic Residual Basins in Yellow Sea, and analyzes its macro-distribution characteristics. Gravity inversion is applied on a typical geological profile in Yellow Sea to analyze the characteristics of its fractures and magnetic basements. The characteristics of Pre-Cenozoic Residual Basins distribution outline in Yellow Sea and the fractures and magnetic basements of its typical profile shown by profile inversion provides new geophysical evidence for these structure views such as “the South Yellow Sea and the North Yellow Sea belong to different structural units” and “Sino-Korea and Yangtze blocks combine along Yellow Sea East Fractured Zone in Yellow Sea”.

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The large ancient underground rock caverns in Longyou is an important component of grotto cultural. Current task facing the long-term preservation of these unmovable cultural relics is arduous and challenging. The deformation failure of the caverns' surrounding rock is deteriorating. The weathering velocity of these caverns is accelerating. With the strength of caverns' surrounding rock worsening, critical rocks were generated in local regions of the caverns' vault and posing a threat to the security of people passing by. Selection of a maximum-security route and construction a aisle in the caverns might be an efficient way to ensure the security of tourists and reach the target of long-term preservation. The deformation and destruction of the ancient underground caverns is primarily dominated by geological conditions and the special structure of caverns. Based on field investigation, several fundamental conditions for deformation and failure are recognized, and nine deformation and fracture patterns of the Longyou grotto are proposed. In order to judge the stability of caverns’ surrounding rock, the element safety coefficient method is presented. An explicit explanation for the meaning of the method is deduced using Mohr-Coulomb strength criterion. Numerical analyses are carried out in the dissertation through FLAC3D code. Through numerical analysis, the stress distribution regularities of the caverns’ roofs, piles and public side wall are analysed, and the stability properties of caverns’ surrounding rock are also assessed. At the same time, the element safety coefficient method is introduced to contrast the stability degree of different regions in caverns. The above analyses are bases for choosing the optimal tourism routes in the caverns of Longyou grotto. The impact of surface load on the stability of shallow buried cavities in Longyou grotto is evaluated, the results show that building load has significant influence on the stability of the No.1 cavern’s roof, pile and public side wall between the No.1 cavern and the No.2 cavern, pedestrian load has less impact on the stability of surrounding rock than building load. The principles for choosing the optimal tourism routes in the caverns are discussed. With these principles, the dissertation makes a systematic research on the geological analytic method, numerical analytic method and meeting tourism requirements method, which are used in selecting the optimal tourism routes in the caverns. In order to achieve the best effect in the process of tourism routes selection, the above three method are integrated through Theory of Engineering Geomechanics Meta-system(EGMS). According to field investigations, numerical analyses, tourism requirements and expert experiences, the optimal tourism routes through No.1 to No.5 cavern are determined preliminarily. The obtained results from the research work are useful for the security aisle's construction, they also have reference value to other projects in practice.

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Stigma is defined as a sign of disgrace or discredit that sets a person apart from others. Stigmatized individuals had been significantly influenced by their group-based stigma. Through the methods of laboratory experiment and questionnaire surveys, the current study started with examining the attitudes of middle school students to the students with learning disabilities (LD), systemly explored the characteristics of perceived stigma and self-stigma of LD students, the mechanism that the influences of stigma on students with LD, and the mental control required to cope with the stigma. The results of the present studies had significant implications for the understanding of the LD phenomenon and the intervention of LD adolescents. The results indicate that: 1. Generally, middle school students had negative implicit attitude and negative explicit attitudes towards the LD students. The effect size of the phenomenon of this study is large. The LD students showed a more positive attitude than others on the explicit attitude measure; all students consistently had negative attitudes toward LD students on the implicit attitude indices, in addition, no group differences and gender differences were observed in the implicit attitude. 2. Eight hundred and seventy two students were surveyed to test the reliability and validity of the new developed perceived stigma scale and self-stigma scale. Both questionnaires showed sufficient content validity, construct validity, criterion-related validity and adequate internal consistency reliability. Then, both questionnaires were administered to student with high academic achievement (high achiever), students with middle academic achievement (middle achiever), and LD students. Results revealed that the LD students mildly stigmatized by the social culture. The LD students had more stigma perception and self-stigma than the middle achievers and high achievers. The results also indicated that there were more stigma perception and self-stigma for LD students in grade two than that of LD students in grade one and grade three; meanwhile, male LDstudent hade more stigma perception and self-stigma than female LD students in all grades. 3. A latent variable path analysis was conducted to investigate how the stigma affect the academic goals using the data collected from 186 LD students. The results suggested that the LD-related stigma did not have direct influence on academic goals. The LD-related stigma indirectly influenced the academic goals through mediating effects of self-stigma and academic efficacy. 4. Stereotype threat could have some influences on the relationship between the task feedback and self-esteem. The results of study using eighty-four LD students showed that: when the negative stereotype was not primed, the self-esteem of the LD students was significantly influenced by the feedback of the task: an enhance self-esteem following a positive feedback and a lower self-esteem following a negative feedback. When the negative stereotype was primed, there was no significantly difference between the positive feedback group and negative feedback group. All the results showed that priming the negative stereotype could weaken the influence of feedback to the self-esteem of LD students. 5. There was more cognitive and behavioral control when LD students tried to cope with the stigma by concealing negative academic achievement during an individual interview with an unfamilar expert. The LD students whose academic achievements could be concealed had more thought suppression and thought intrusion and reported more self-monitoring behavior than the participants in the other experimental conditions.

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The present paper studied the school bullying and the primary impact factors, for understanding the nature of bullying, and providing measures and references to the elimination and controlling of school bullying. Primarily with methods of questionnaires and psychometrics, combined with case study and interviews, the following findings were found: in Chinese culture, bullying is a behavior intentionally causing harm to the weaker or weakers. There were 5 types of bullying-physical, social exclusion, threat, breakage and verbal. In Chinese schools the occurrence of bullying had regular patterns. The factor that impact children's bullying behavior was personality traits, interpersonal techniques, family atmosphere, education and upbringing styles. In personality traits, bullies tended to be more extroversive, impulsive, obstinate, obdurate and lack of sympathy. Victims tended to be more introversive, self-restrained, lack of confidence, lonely, anxious and depressive. Both of them expressed more mental problem tendencies than normal children did. When confronted with interpersonal conflicts, they used little problem solving strategies. Bullies had more extroverted emotional responses, and victims had more social support strategies. In the light of family influence, bullies were relatively superior in family's social economic conditions. But their parents had little time and energy spent on them. They tended to be punitive, and had indulgent, reject or despotic upbringing styles. The role of victim might be related to the disadvantage of family's social economic status. Their parents had the tendency of spoiling and overindulgence. The research concluded that in different cultures the connotation of bullying was not homogenous. The occurrence of school bullying had regular patterns. Bullying behavior was primarily influenced by the personality traits of both bullies and victims, the coping strategies of interpersonal conflicts, family's social economic status, parents' basic emotional attitudes, ways of educating, punitive tendencies and school atmosphere. The occurrence of bullying behavior was the result of the combined process of past experience, behavior habits, personality traits, cognitive evaluation, certain evocative clues and the environment conditions. It reminded that quality education and mental health education in schools was essential. Strengthening basic social skill training in school, creating positive family atmosphere, having more communications between schools and families and implementing strict regulations against bullying was essential to interfere and eliminate the school bullying.