渭南地区末次冰期以来的蜗牛化石记录及古气候古环境研究

In this study, 172 mollusk assemblages from the Weinan loess section in the southeast of Loess Plateau, China, were identified quantitatively at relative high resolution. The results show: 1) the history and processes of paleoclimatic and paleoenvironmental changes in Weinan since the last 70 ka; 2) the characteristics of climatic changes during the period of the last glacial maximum (LGM); 3) the spatial pattern of paleoclimate variations at the south and middle parts of the Loess Plateau during the LGM period; 4) the timing of the last deglaciation and the return event of rapid climate change during the last deglaciation. The main conclusions are as follows: 1) 172 mollusk samples taken from the uppermost 9 m deposits cover the past 70 ka, which were sampled at the internals of 5 cm for S_0, 3 cm for L_(1-1) and L_(1-2), and 10 cm for L_(1-3), L_(1-4) and L_(1-5). Author analyzed quantitatively all individuals including broken pieces of snail shells, percentages of 15 species identified from 172 samples. Three main groups were determined according to the ecological requirement of each taxon. Based on the variations of three ecological groups and typical ecological species, The author intended to reconstruct the history of and processes of climate and environment since the last 70 ka in the Weinan region. The climate and environment in this region experienced the following changes: relative warm and humid stage from 67.5-20.3 cal. ka B.P., a period of forest-steppe or steppe developed; cold and arid stage from 20.3-15.5 cal. ka B.P., a dry steppe period, later wetter and colder; cold and humid period once time from 15.5 to 12.3 cal. ka B.P., a typical steppe or forest-steppe stage; cold and humid again from 12.3 cal. ka B.P. to 8.2 cal. ka B.P., a tropical steppe stage; warm and humid climate, a forest-steppe developed. 2) The climate during the period of the last glacial maximum (LGM) in Weinan was characterized by a general cold-humid condition, represented by occurrence of a number of the cool-humidiphilous mollusk species such as Gastocopta amigerella and Vallonia cf. pulchella in the section. 3) Comparison of the variations in abundance of Puncture orphana at Weinan with those at Luochuan and Changwu sections suggests that the summer monsoon intensity influenced differently at the three regions during the LGM period. The Weinan was weaker summer monsoon impact during all the period, the Luochuan was influenced occasionally, and Changwu was only a very short time affected, which indicated it might be located at the western margin of the summer monsoon influence during that period. 4) The ratio of thermo-humidiphilous mollusk group to cold-aridiphilous one shows an increase tendency at about 15 cal. ka B.P., reflecting the climate warming after the deglaciation in Weinan, which is approximately corresponding to the timing of warming period of the last deglaciation, found in the East Atlantic Ocean, the South China Sea and the Loess Plateau (indicated by the phytolith study). 5) A remarkable decrease in the number of thermo-humidiphilous and cool-humidiphilous mollusk species from 12.7 - 11.6 cal. ka B.P. indicates a cooling in climate and might be the reflection of the Younger Dryas event in Weinan. 6) Variations in the ratios of thermo-humidiphilous mollusk species to cold-aridiphilous ones reflect the climate instability in Holocene. There were four warm-humid periods (10-8.1 cal. ka B.P., 6.9-6.1 cal. ka B.P., 5.2-2.6cal. ka B.P., 1.6cal. ka B.P. to the present ) and three relative cold-arid periods (8.1-6.9 cal. ka B.P., 6.1-5.2 cal. ka B.P., 2.6-1.6 cal. ka B.P.), showing about a 1,000 year climatic oscillation.

石笋微层序列的断代和信号研究

Based on chronological and climatologic analysis of many young stalagmites in Shihua Cave at Beijing and Water Cave in Benxi, Liaoning Province, this dissertation aims to discuss some key points on quantitative reconstruction of high resolution climate change from micro bands time series in young stalagmites. On chronological aspect of micro bands time series in young stalagmite, the uppermost micro bands were testified formed in the sampling year or the year before sampling from long term and in situ experiment in Shihua Cave at Beijing. Have been observed detailed under microscope, the micro bands were counted and compared with high resolution TIMS-230Th or ICP-MS U series dating, the results show that the micro bands are annual bands. The microscopic characteristics of annual bands in North China is as follows after studying lots of young stalagmites: the interface appears to be carved, and there is a light line adjacent to it, which moves back and forth slightly when adjusting the microscope slide. The cross dating of annual bands from different stalagmites is experimented in this thesis. On climatologically aspect of micro bands times series in young stalagmites, one significant problem is that the deposition trend resulting from the variation of the stalagmite shape. Various deposition trends have been discussed and corrected before climatologically analysis of micro bands series. And the whole year in situ observation and analysis of dripping water in Shihua Cave provide us new evidence for climate information reserved in stalagmites micro bands. The stalagmites in the same cave may contain different climate information due to the micro hydrological condition. The annual bands of young stalagmites collected from North China can be used to reconstruct past climate changes quantitatively. The warm season temperature (May, June, July, August) is reconstructed using two annual bands time series from Shihua Cave, Beijing, which corresponds to the warm/cool periods very well in Chinese history documents. The precipitation record of past 500 years is reconstructed using two stalagmite annual bands series from Shihua Cave, which is consistent to the dryness/wetness records derived from historical documents too.

湛江湖光岩玛珥湖55ka以来植硅体化石记录及古环境变迁

The study of biogenic proxy of tropical and subtropical regions provides important evidence about the process and history of vegetation and environmental changes, and is of globally importance for understanding the dynamic mechanism of paleoclimatic and paleoenvironmental changes. The sediments from the Huguangyan Maar lake in Guangdong Province offer a continuous high-resolution record of the past 55 ka about environmental and vegetational changes. The studies of chronology, and physical, chemical environmental proxies have provided much important information about the paleoenvironmental and paleoclimatic histories. The phytolith, a new biogenicl proxy, has been used to determine the nature and types of plants in this area since the last 55 ka. This study presents a preliminary result about the characteristics of phytolith shapes, the variations of the fossils assemblages, and their significance for environmental changes. Moreover, the author probes the process of special specie evolution and their relationship to climatic parameters. The history of fire has been reconstructed based on the variations in charcoals. The main results and conclusions include: 28 types of phytoliths from 233 samples have been identified. Their environmental meanings are investigated in detail. Based on the variations in phytolith associations, the history and process of climatic and environmental changes in the last 55 kaBP have been established for this region. Climatic changes experienced eight intervals during this period, showing the variations of hot-humid to cool-try climate in the ten thousands years scale, and a shorter dry-hot climate condition in millennial scale. The history of palm plant has been established in this region. Two peaks appeared from 55-39 ka and since the Holocene. Plants in Bambusoideae have been growing in this area all the period, representing the impact of the East Asian summer monsoon. Bamboo plants have similar tendency in their abundance to palm plants, but with a lag of 1-2 ka BP. Panicoideae plants, the representative of C4 plants, have 6 flourishing periods occurred at 54.5, 44, 41.5, 32.5, 14, and 10 kaBP, respectively, reflecting 6 times short-term arid events. Charcoal record from the Huguang Marr lake reveals the history of nature fire, that mostly happened in dry period of last glacial from 55-10 kaBP, centered at 50-45, 40-35, 30-25, and 20-15kaBP, showing about a cycle of 10,000 years.

中国南方热带地区田洋玛珥湖24万年以来的气候变化及湖泊演变

A continuous long (224m) and high-resolution core TY2 was recovered from paleo-maar-lake Tianyang, tropical South China. Based on the diatom records of the upper 130-m core, this paper focuses on exploring climate change and the lake evolution history in tropical South China during the past 240ka. The most typical and unique characteristics of the diatom assemblages is that, Aulacoseira granulata was dominant or absolutely dominant species (80-90%) during most parts of the 130-m core, while Cyclotella stelligera var. tenuis and Fragilaria construens var. venter were subdominant species in only limited parts of the lower and upper core, respectively. Time scale is always the biggest problem for the study of TY2 core, so although diatom is seldom used for establishing time scale, here we attempt this by correlating the diatom-reconstructed temperature sequence with the time scale of ODP core 806B from Equatorial Western Pacific. Verified by the few most reliable ages from TY2 core and the parallel core TYl, a rather reasonable and reliable time scale was established. 01S 7/6 falls at the depth of 100m (ca. 194kaBP), OIS 6/5 at 75m (ca. 132kaBP), OIS 5/4 at 46m (ca. 75kaBP), OIS 4-3 at 35m (ca. 60kaBP). Qualitative and quantitative environmental reconstructions are made on the basis of diatom assemblage ecotype and EDDI dataset. Correlation of diatom-reconstructed temperature and moisture changes of Core TY2 with pollen-reconstructed temperature and rainfall sequence of Core TYl proves that the results are quite consistent in most periods. Thus the reconstruction results from diatom are quite reliable, and probably have a much higher resolution than pollen results. Combined with lithological and magnetic susceptibility variations, the diatom analysis reveals that, the general climate in tropical South China during the past 240ka was warm and wet. On the time scale of glacial-interglacial, warm and wet, cool and dry are not always synchronous. It was relatively warm-wet during the penultimate interglacial, cool-dry during the penultimate glacial, warm-dry during the last interglacial, and cooler-drier during the last glacial. In contrast, on the time scale of subglacial-subinterglacial scales, warm and dry, cool and wet corresponds very obviously, showing very clear 21-23 ka precession cycle. Analysis also shows that, the water of Tianyang paleo-maar-lake was generally warm, turbulent, turbid, meso-trophic, slightly alkaline, low conductivity and fresh during the past 240 kaBP, with small variations in some parts. Tianyang paleolake experienced shallow to semi-deep lake in OIS7d, open shallow lake in OIS7c-OIS5b, shallow coastal lake in OIS5a-OIS4c, swamp in OIS4b, and then completely dried up in OIS3c. The lake evolution was mainly controlled by temperature and precipitation changes in tropical China. While temperature and precipitation changes were probably controlled by the migrations of monsoon rainband and the evaporation rate, which was in turn controlled by the evolution of East Asian monsoon. Therefore, when the summer monsoon was strongest the climate was warm-dry, when stronger the climate was warm-wet; when the winter monsoon was strongest the climate was cool-dry, stronger cool-wet. This mechanism caused the warm-dry sub interglacial and cool-wet subglacial climate in the tropical South China.

内蒙古岱海DH99a岩芯沉积物碳含量变化与湖区全新世气候变迁

Daihai Lake, a graben-type closed lake, lies ca. 10 km east of Liangcheng County, Inner Mongolia, north-central China. For its location at the transition of semi-humid and semi-arid areas, and in the north edge of the East Asian monsoon, the lake is sensitive to changes in climate and environment. Based on analyses of total inorganic carbon (TIC), total organic carbon (TOC) and the ratio of total organic carbon to total nitrogen (C/N ratio) of DH99a core sediments recovered in the central part of Daihai Lake, the data suggest Holocene climatic history of the lake region is reconstructed. In this paper, the TIC and TOC contents of the lake sediments are closely related to climate changes. 1) Changes in TIC content of the lake sediments is closely related to climate, which directly reflect changes of temperature in the lake region, i.e., higher TIC content is linked with warmer temperature and stronger evaporation; 2) Changes in TOC and C/N ratio reflect the regional precipitation, i.e., relatively higher TOC content and C/N ratio indicate higher rainfall which results in stronger river flow and more organic matter entering into the lake. Data of the TIC content, TOC content and C/N ratio of DH99a core sediments suggest that climatic history of the Daihai Lake region is characterized by 4 stages. During the interval of ca. 11200-7500 a BP, higher TIC content, relatively lower TOC content and C/N ratio value indicate a warmer and slight dry condition over the lake area. From ca. 7500 to 4500 a BP, high values of TIC content, with an increase in TOC content and C/N ratio suggest the climate was warm and humid. Changes of TIC content, TOC content show that both temperature and precipitation displayed obvious fluctuations during the period, i.e., slightly cool and humid ca. 7500-6700 a BP, warm and moist ca. 6700-5300a BP, mild and comparatively humid ca. 5300-4500a BP. Between ca. 4500 and 2900 a BP, TIC content and TOC content decreased gradually while fluctuating, C/N ratio displayed a decreasing trend. These data imply that the climate generally became cooler and drier than the preceding period. The lowest values of TIC content, TOC content and C/N ratio during the interval of ca. 2900-0 a BP, demonstrate that the climate was severe, and became cool and dry. However the relative higher values of TIC content, TOC content and C/N ratio between ca. 1700 and 1300 a BP may denote an increase both in temperature and in precipitation. Data of TIC content, TOC content and C/N ratio in Daihai DH99a core sediments indicate that the warm period was asynchronous with the humid time, the warm interval began in ca. 11200 a BP, and ended in ca. 2900 a BP. The humid period was ca. 7500-2900 a BP. During ca. 7500^500 a BP, the climate was warm and humid, which was the climatic optimum of the Holocene Epoch in the Daihai Lake region. Data of TIC content, TOC content and C/N ratio in Daihai DH99a core sediments imply that the Holocene climate was unstable, the fluctuating events happened occasionally. Such as the cold and dry climate in ca. 4400-4200a BP, the warm and humid climatic condition in the period between ca.1700 and 1300a BP.

宁夏固原寺口子剖面磁性地层与孢粉植物群初步研究

In Asia continent, several significant environmental events happened during the Cenozoic era, such as uplift of the Tibet Plateau, formation of the Asian Monsoon system, aridification of the temperate inland region in Central Asia. To investigate the history of long-term palaeoclimate evolution during the late Cenozoic, a lacustrine sequence located at Sikouzi, Guyuan county, Ningxia-Hui Autonomous Region, was studied. The Sikouzi section is about 2880 m in thickness and has a general continuous nature according to field observation. Thus this thick lacustrine record is an important archive to further understand those environmental events. In this study, detailed field measurement, layer-after-layer description and sampling, and magnetostratigraphy and palynoflora investigations are conducted at the Sikouzi section and some preliminary results have been achieved as follows. Based on Hipparion fauna, pollen data and long distinctive patterns of the local magnetozones, the confident correlation of the Sikouzi magnetostratigraphic polarity to the GPTS (CK95) is best established, indicating that the top boundary of the Sikouzi formation is dated back to -19.8 Ma B.P. and consequently no Oligocene sediments deposited locally. On the other hand, both the field observation and the correlation to GPTS indicate a nearly continuous nature for the whole sequence. The palynological results show that the grassland has been a dominant vegetation in the Sikouzi area since ~19.8 Ma B.P, although some trees/shrubs were present sparsely during the intervals of relatively warm and wet climatic conditions. This implies that the onset of the aridification in northwestern China is dated back to at least 19.8 Ma B.P. ago. The Neogene Global Climatic Optimum (-16.0 Ma B.P.) occurring between the late Early Miocene and the early Middle Miocene is well documented in the Shanwang formation, Shandong Province. However, such event was not found in the Sikouzi record, and neither in the Guide and the Hualong basins, Qinghai province. This may lead us to the conclusion that the East-Asian Summer Monsoon system remained weak during the period of the Miocene Climatic Optimum although the onset of it was traced back to the Early Oligocene. In the Sikouzi area, it was warm between the latest Miocene and the early Pliocene and then became cool in the late Pliocene. This pattern is consistent with the palaeoclimate record of the Pliocene from other areas in the world.

通过对心理学期刊的几项统计分析看我国十年来儿童发展教育心理学研究状况与动向

In this study, bibliometric method was usded in the investigation of 2274 papers concerning child developmental and educational psychology, which were published during the ten years of 1979-1988, in 14 psychological journals and 97 other scientific journals. According to the quantitative and qualitative analyses, the results are as follows: 1979-1988 saw the rapid development and prosperous period in China's child developmental and educational psychology, During which more papers were published and more fields couched than in the psvious thirty years. The number of literature publications increased and went to the peak in 1983 and 1984, and came down since 1985. The trend was found to result from the decrease in popular science introductions of psychology, which reflected that a heat of psychology had appeared in 1983 and started to cool in 1985. At the mean time, the number of research reports had been holding a steady increase by 1987 and decreased obviously in 1988, especially in the fields of cognitive and social development. There could be several possible explanations of this phenonemon: Piagetian studies are becoming fewer and the eakening of Piaget's influence might predict a period of standstill in the field of developmental psychology in China; As researches become more and more difficult, researchers have turned to be more cautious in lay out their reports; the cutdown of fees and staff could also be one of reasons for less publication in 1988. As the factors mentioned above still exist and their influences last, the number of papers are not expected to increase in the near future. The field of thinking and menory is closely connected with that of artificial intelligence. The downhill situations in these two fileds should be taken seriously. 2. The types of research work are divided on the bases of their problem raising. The trends show that the deepening studies, which represent a comaratively higher level of exploration, are waving fewer, while repeated studies and creative studies are becoming more as the years go along. This fact is worth being further analysed. Big progress could be seen from research methods. The methods currently used are mainly experiment, psychological measurement and assessment, and theoretical reasoning. There is a rapid increase of research by using scales. Wechsler Intelligence Scale for Children, Binet Scale and Baley Scale have been revised andstandardized. Chinese researchers have also developed several good scales of their own, some of which are valuable and need to be standardized. In the papers investigated, the amount of citation is significantly lower than the world average level as well as the average citation number of whole China's scientific literature. Among the papers cited, most are of Chinese and English languages, and only a small rate were published in resently five years. The renewal of literature cited seems to stay at a low level in the ten years. Tremendous work could be reflected by the number of subjects used the research work in those ten years: 362665. A lot of studies piled on the period of 4-16 year olds. Compared with the previous thirty years, the age range was much enlarged and there were quite a few studies about preschool, school and adolescent periods. The study of newborn of 0-3 has been a weak point so far and it is a field to which chinese developmental psychologists should pay more attention. The progress in using statistics is one of the most obvious part in the development in the research work of child developmental and educational psychology. The one tendency that should be awared and avoid is to put the cart before the horse: seeking for more sophisticated statistic method while neglecting the meanings of research problems. 3. Citation analysis was used in selecting scholars who had great influence in the field of child developmental and educational psychology. Among the often cited and famous scholars, 31 are Chinese researchers and 12 are Western psychologists. The authoritative journal for child developmental psychology and educational psychology is Acta Psychologica Sinica.

Shape Recipes: Scene Representations that Refer to the Image

The goal of low-level vision is to estimate an underlying scene, given an observed image. Real-world scenes (e.g., albedos or shapes) can be very complex, conventionally requiring high dimensional representations which are hard to estimate and store. We propose a low-dimensional representation, called a scene recipe, that relies on the image itself to describe the complex scene configurations. Shape recipes are an example: these are the regression coefficients that predict the bandpassed shape from bandpassed image data. We describe the benefits of this representation, and show two uses illustrating their properties: (1) we improve stereo shape estimates by learning shape recipes at low resolution and applying them at full resolution; (2) Shape recipes implicitly contain information about lighting and materials and we use them for material segmentation.

RamboNodes for the Metropolitan Ad Hoc Network

We present an algorithm to store data robustly in a large, geographically distributed network by means of localized regions of data storage that move in response to changing conditions. For example, data might migrate away from failures or toward regions of high demand. The PersistentNode algorithm provides this service robustly, but with limited safety guarantees. We use the RAMBO framework to transform PersistentNode into RamboNode, an algorithm that guarantees atomic consistency in exchange for increased cost and decreased liveness. In addition, a half-life analysis of RamboNode shows that it is robust against continuous low-rate failures. Finally, we provide experimental simulations for the algorithm on 2000 nodes, demonstrating how it services requests and examining how it responds to failures.

Qualitative Process Theory

Objects move, collide, flow, bend, heat up, cool down, stretch, compress and boil. These and other things that cause changes in objects over time are intuitively characterized as processes. To understand common sense physical reasoning and make programs that interact with the physical world as well as people do we must understand qualitative reasoning about processes, when they will occur, their effects, and when they will stop. Qualitative Process theory defines a simple notion of physical process that appears useful as a language in which to write dynamical theories. Reasoning about processes also motivates a new qualitative representation for quantity in terms of inequalities, called quantity space. This report describes the basic concepts of Qualitative Process theory, several different kinds of reasoning that can be performed with them, and discusses its impact on other issues in common sense reasoning about the physical world, such as causal reasoning and measurement interpretation. Several extended examples illustrate the utility of the theory, including figuring out that a boiler can blow up, that an oscillator with friction will eventually stop, and how to say that you can pull with a string but not push with it. This report also describes GIZMO, an implemented computer program which uses Qualitative Process theory to make predictions and interpret simple measurements. The represnetations and algorithms used in GIZMO are described in detail, and illustrated using several examples.

Natural Language Input for a Computer Problem Solving System

The STUDENT problem solving system, programmed in LISP, accepts as input a comfortable but restricted subset of English which can express a wide variety of algebra story problems. STUDENT finds the solution to a large class of these problems. STUDENT can utilize a store of global information not specific to any one problem, and may make assumptions about the interpretation of ambiguities in the wording of the problem being solved. If it uses such information or makes any assumptions, STUDENT communicates this fact to the user. The thesis includes a summary of other English language questions-answering systems. All these systems, and STUDENT, are evaluated according to four standard criteria. The linguistic analysis in STUDENT is a first approximation to the analytic portion of a semantic theory of discourse outlined in the thesis. STUDENT finds the set of kernel sentences which are the base of the input discourse, and transforms this sequence of kernel sentences into a set of simultaneous equations which form the semantic base of the STUDENT system. STUDENT then tries to solve this set of equations for the values of requested unknowns. If it is successful it gives the answers in English. If not, STUDENT asks the user for more information, and indicates the nature of the desired information. The STUDENT system is a first step toward natural language communication with computers. Further work on the semantic theory proposed should result in much more sophisticated systems.

The Net and the Self: Colliding Views of Individuality and Nationhood in the Pre-Devolutionary plays of Mark Jenkins and Ed Thomas

Owen, Roger, 'The Net and the Self: Colliding Views of Individuality and Nationhood in the Pre-Devolutionary plays of Mark Jenkins and Ed Thomas', In: 'Cool Britannia: British Political Drama in the 1990s', Rebecca D'Mont? and Graham Saunders (eds), (Basingstoke: Palgrave Macmillan), pp.158-175, 2007 RAE2008

Aplicação de MonetDB na avaliação de desempenho de bases de dados verticais

Dissertação apresentada à Universidade Fernando Pessoa como partes dos requisitos para a obtenção do grau de Mestre em Engenharia Informática, ramo de Sistemas de Informação e Multimédia

The Information Commons: a public policy report

This report describes the history of the information commons, presents examples of online commons that provide new ways to store and deliver information, and concludes with policy recommendations. Available in PDF and HTML versions.

EVALUATION OF HARMONIC MOTION ELASTOGRAPHY AND ACOUSTO-­OPTIC IMAGING FOR MONITORING LESION FORMATION BY HIGH INTENSITY FOCUSED ULTRASOUND

Malignant or benign tumors may be ablated with high‐intensity focused ultrasound (HIFU). This technique, known as focused ultrasound surgery (FUS), has been actively investigated for decades, but slow to be implemented and difficult to control due to lack of real‐time feedback during ablation. Two methods of imaging and monitoring HIFU lesions during formation were implemented simultaneously, in order to investigate the efficacy of each and to increase confidence in the detection of the lesion. The first, Acousto‐Optic Imaging (AOI) detects the increasing optical absorption and scattering in the lesion. The intensity of a diffuse optical field in illuminated tissue is mapped at the spatial resolution of an ultrasound focal spot, using the acousto‐optic effect. The second, Harmonic Motion Imaging (HMI), detects the changing stiffness in the lesion. The HIFU beam is modulated to force oscillatory motion in the tissue, and the amplitude of this motion, measured by ultrasound pulse‐echo techniques, is influenced by the stiffness. Experiments were performed on store‐bought chicken breast and freshly slaughtered bovine liver. The AOI results correlated with the onset and relative size of forming lesions much better than prior knowledge of the HIFU power and duration. For HMI, a significant artifact was discovered due to acoustic nonlinearity. The artifact was mitigated by adjusting the phase of the HIFU and imaging pulses. A more detailed model of the HMI process than previously published was made using finite element analysis. The model showed that the amplitude of harmonic motion was primarily affected by increases in acoustic attenuation and stiffness as the lesion formed and the interaction of these effects was complex and often counteracted each other. Further biological variability in tissue properties meant that changes in motion were masked by sample‐to‐sample variation. The HMI experiments predicted lesion formation in only about a quarter of the lesions made. In simultaneous AOI/HMI experiments it appeared that AOI was a more robust method for lesion detection.