首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
This essay presents a variety of medieval Tibetan Buddhist dream practices culled from many different sources, such as medical texts, biographies, religious texts, and folklore. Some of this material is here translated into English for the first time. The dreaming techniques presented in these texts bring out religious and philosophical connections between body and consciousness. The range and diversity of the original sources required a broad interdisciplinary approach using literary studies, religious studies, philosophy, linguistics, and other disciplines.  相似文献   

2.
Functional Implications of Allogrooming in Cercocebus torquatus   总被引:1,自引:0,他引:1  
We examined the hygienic functional hypothesis of allogrooming in two captive groups (N = 9 and N = 8) of white-crowned mangabeys (Cercocebus torquatus lunulatus) by analyzing the corporeal distribution of allogrooming solicitations according to the variable degree of accessibility of the various body sites. We used focal-animal sampling and continuous recording and nonparametric statistics (sing test and 2). The fact that in both groups more allogrooming was solicited to sites associated with accessibility problems is consistent with the hygienic functional hypothesis of allogrooming. In any case, there are two facts that suggest that this hypothesis cannot account for all the characteristics of such behavior: 1) the strong distributional selectivity shown by allogrooming solicitations—they concentrated primarily on dorsal and caudal regions instead of those difficult to reach or inaccessible on the whole—and 2) the significant role played by sex in the intragroup distribution of anogenital solicitations. Supporting the multifunctional nature of allogrooming, we find very appealing the ritualization hypothesis, according to which the allogrooming performed on certain body sites would have acquired a sociocommunicative meaning.  相似文献   

3.
 Existing artificial neural network models are not very successful in understanding or generating natural language texts. Therefore it is proposed to design novel neural network structures in higher levels of abstraction. This concept leads to a hierarchy of network layers which extract and store local details in every layer and transfer the remaining nonlocal context information to higher levels. At the same time data compression is provided from layer to layer. The use of the same network elements (meta-words) in higher levels for different word series in the basis level is introduced and discussed for grammatical identity or similarity. Thus text can be compressed to forms which are almost free of redundancy. Possible applications are storage, transmission, understanding, generating and translation of texts. Received: 6 May 1993 / Accepted in revised form: 24 July 1996  相似文献   

4.
Over the last decade, disabled veterans of the Turkish Army who were injured while fighting against the Partiya Karkerên Kurdistan (PKK; Kurdistan Workers' Party) have become national icons and leading ultranationalist actors. While being valorized as sacrificial heroes in nationalist discourse, they have also confronted socioeconomic marginalization, corporeal otherness, and emasculation anxieties. Against this backdrop, disabled veterans' organizations have become the locus of an ultranationalist campaign against dissident intellectuals. Building on two years of ethnographic research with disabled veterans in Turkey, this article analyzes these processes through the analytical lens of the body. Locating the disabled veteran body at the intersection of state welfare practices, nationalist discourses on heroism and sacrifice, and cultural norms of masculinity and disability, I illustrate how disabled veterans' gendered and classed experiences of disability are hardened into a political identity. Consequently, I show how violence generates new modalities of masculinity and political agency through its corporeal effects.  相似文献   

5.
The changes in dry mass, wet mass and energy content were determined during the establishment of the incipient colony. The winged reproductives of H. mossambicus are weak fliers. It is postulated that the alates compensate for the large quantity of reserve material by reducing their body water. The wet mass of both males and females increased significantly (twice original mass) from emergence until the first larvae appeared which tends support to this view. Furthermore, although the termites maintained in groups imbibed water, it is also clear that the reproductives, as long as they remain social, maintain the same low body-water content. This desiccated physiological condition appears to be and adaptation which assists flight and dispersal. In contrast with sterile eggs, fertile eggs absorbed water during development. The paired females (normal and homosexual) maintained the same energy/unit wet mass from egg production until the first workers appeared. Thus the possibility exists that the hydrophobic reserves (e.g. triglycerides) were converted to the hydrophilic reserves (e.g. carbohydrates). The same applied to the eggs and offspring.The changes in dry mass, wet mass, body water and energy content of females per unit of eggs (specific mass) produced were 0.005, 8.696, 21,276 and 12.820 respectively. The small specific dry mass value can probably be ascribed to the use of small amounts of glycerides and the increase in dry mass by the conversion from relatively light and “compact” glycerides to relatively heavy and “bulky” glycogen.Females utilised far more dry mass and energy in comparison to males to survive until the first workers appeared. Wet mass, body water and energy used in rearing of the offspring shows clearly that males made a larger contribution to the water and energy requirements of the offspring.  相似文献   

6.
S B Smith  A J Bendich 《Biopolymers》1990,29(8-9):1167-1173
Individual ethidium-stained DNA molecules, embedded in an agarose gel made with electrophoresis buffer (0.05 molar salt), are observed using a fluorescence microscope. In the first experiment, open circular 66 kilobase pair (kbp) plasmids, immobilized by agarose fibers threaded through their centers, display entropic "rubber" elasticity. The charged molecules extend in an electric field of several volts per centimeter and contract to a compact random coil when the field is removed. The extension of the plasmids as a function of field strength is consistent with the freely jointed chain model when the effective electrophoretic charge density is set at 15 e-per persistence length. In a second experiment, stained linear 48.5 kbp DNA molecules are observed as random coils immobilized in agarose. A measure of their size, here named the "maximal-X-extent," is taken for 100 molecules and found to average 1.47 mu. A Monte Carlo computer simulation of random coils (freely jointed chain model) gives the same maximal-X-extent value when the persistence length is set at 0.08 mu.  相似文献   

7.
Creationism is a religiously motivated worldview in denial of biological evolution that has been very resistant to change. We performed a textual analysis by examining creationist and pro-evolutionary texts for aspects of “experiential thinking”, a cognitive process different from scientific thought. We observed characteristics of experiential thinking as follows: testimonials (present in 100% of sampled creationist texts), such as quotations, were a major form of proof. Confirmation bias (100% of sampled texts) was represented by ignoring or dismissing information that would contradict the creationist hypothesis. Scientifically irrelevant or flawed information was re-interpreted as relevant for the falsification of evolution (75–90% of sampled texts). Evolutionary theory was associated to moral issues by demonizing scientists and linking evolutionary theory to atrocities (63–93% of sampled texts). Pro-evolutionary rebuttals of creationist claims also contained testimonials (93% of sampled texts) and referred to moral implications (80% of sampled texts) but displayed lower prevalences of stereotypical thinking (47% of sampled texts), confirmation bias (27% of sampled texts) and pseudodiagnostics (7% of sampled texts). The aspects of experiential thinking could also be interpreted as argumentative fallacies. Testimonials lead, for instance, to ad hominem and appeals to authorities. Confirmation bias and simplification of data give rise to hasty generalizations and false dilemmas. Moral issues lead to guilt by association and appeals to consequences. Experiential thinking and fallacies can contribute to false beliefs and the persistence of the claims. We propose that science educators would benefit from the systematic analysis of experiential thinking patterns and fallacies in creationist texts and pro-evolutionary rebuttals in order to concentrate on scientific misconceptions instead of the scientifically irrelevant aspects of the creationist—evolutionist debate.  相似文献   

8.
The life cycle ofC. carinata (Krøyer) from the Kiel Canal and the seasonal change of its population structure have been studied.C. carinata is a protogynic hermaphrodite which may attain an age of 3 years. The young are born in summer and only very few reach sexual maturity during the following year. Some of them become functional small males without passing through a female stage. At the end of the breeding season, some individuals of the same generation become functional females. They moult into pre-males during winter and are functional males in the following summer, when they are 2 years old. The remaining two-year-old animals are breeding females. Mature females can be recognized by the presence of antennules with four jointed flagella and 3 pairs of oostegites. In September they moult to pre-males which have antennules equipped with six jointed flagella. In June of the following (third) year they become functional males which die at the end of the breeding season. It is supposed that this cycle also applies for population from the Gdansk Gulf studied by Jadewski (1969) despite a different interpretation given by this author.  相似文献   

9.
A two dimensional continuum model for the body mechanics of the lamprey is derived from a simple discrete rod and pivot structure. Each element in the discrete structure consists of two smoothly jointed light rods with perpendicular extensions at each of the midpoints between which is fixed a quasi muscle segment. The muscle segment is attributed with the viscous and elastic properties of all the animal tissue plus the ability to produce force. The travelling wave of muscle activation in the real animal is modelled by a corresponding time dependent forcing term at each segment. A linearisation of the ensuing continuum model, corresponding to low curvature dynamics, is investigated. The profiles obtained compare favourably with those of a lamprey moving out of water on a smooth surface. In addition the phase difference at each point on the body between the wave of muscle activation and the mechanical wave observed on the body indicates that the mechanical wave progresses slower than, but at the same frequency as, the wave of activation; this is a property that is also observed in the freely swimming lamprey.  相似文献   

10.
A single duodenal ulcerogenic dose of cysteamine administered into rats induced time-dependent depletion of immunoreactive somatostatin in the gastric corporeal, antral, and duodenal mucosa with a parallel increase (up-regulation) of somatostatin binding sites. The concentration of somatostatin binding sites returned to the control level in the corporeal mucosa when measured at 24 hrs; however, in the duodenal mucosa there was only a partial return to the control level. Somatostatin binding sites in the antral mucosa did not return to control level even after 24 hrs. Except for the duodenum mucosal immunoreactive gastrin level was unaffected by cysteamine administration, but corporeal mucosal gastrin I binding sites were diminished (down-regulation) after 24 hrs.  相似文献   

11.
We compare directly under flow two commonly used coarse grained models of linear polymers, namely the flexible finitely extensible nonlinear elastic (FENE) chain, and the freely jointed tangent sphere chain, otherwise known as the freely jointed chain. The comparison is based on viscometric, structural and dynamical properties. We use non-equilibrium molecular dynamics to simulate steady-state systems under planar Couette flow and planar extensional flow. Computed properties include shear and elongational viscosities, normal stresses, radius of gyration and end-to-end distances, order parameters, alignment angles and spin angular velocities. In all computed properties we observe very little difference between the two molecular models. Therefore, the choice of either model is suitable, though there is a computational advantage in the use of the FENE model.  相似文献   

12.
This study focuses on phylogenetic relationships in two distinct species assemblages of cave-dwelling beetles with similar disjunct distributions in the Pyrenees and Sardinia. One assemblage contains six species in the genera Ovobathysciola (four species) and Patriziella (two species) on Sardinia and one species of Anillochlamys in the Pyrenees. Species within the two Sardinian genera co-occur in the same karst area. Although, they are believed to be each others closest relative, they have very different body types (globular body with short appendages in Ovobathysciola; elongated body with long appendages in Patriziella), which are believed to reflect different degrees of adaptation to cave life. The other assemblage of Bathysciine beetles includes three species in the genus Speonomus in the Pyrenees and one on Sardinia. All the species are rare and many are endangered. One issue of particular interest was whether Ovobathysciola and Patriziella are reciprocally monophyletic or whether each of the Patriziella species evolved independently from the co-occurring Ovobathysciola species, as the similar morphology of the Patriziella species might be due to convergence rather than common descent. Based on DNA sequences of the cytochrome oxidase I (COI) region of the mtDNA, neither scenario was supported. Rather, the two Patriziella species are sister taxa embedded within the Ovobathysciola radiation. In addition, the well-dated geological history of this region allowed us to calibrate absolute rates of COI evolution, the first such estimates for any insect. Finally this study suggests that the evolutionary acquisition of typical cave adaptations (e.g., elongated body and appendages) may occur at about the same rate as loss of traits (e.g., eyes and pigmentation) associated with cave life.  相似文献   

13.
Ecological theory predicts that if animals with very similar dietary requirements inhabit the same landscape, then they should avoid niche overlap by either exploiting food resources at different times or foraging at different spatial scales. Similarly, it is often assumed that animals that fall in different body mass modes and share the same body plan will use landscapes at different spatial scales. We developed a new methodological framework for understanding the scaling of foraging (i.e. the range and distribution of scales at which animals use their landscapes) by applying a combination of three well‐established methods to satellite telemetry data to quantify foraging patch size distributions: (1) first‐passage time analysis; (2) a movement‐based kernel density estimator; and (3) statistical comparison of resulting histograms and tests for multimodality. We demonstrate our approach using two sympatric, ecologically similar species of African ducks with quite different body masses: Egyptian Geese (actually a shelduck), and Red‐billed Teal. Contrary to theoretical predictions, the two species, which are sympatric throughout the year, foraged at almost identical spatial scales. Our results show how ecologists can use GPS tracking data to explicitly quantify and compare the scales of foraging by different organisms within an animal community. Our analysis demonstrates both a novel approach to foraging data analysis and the need for caution when making assumptions about the relationships among niche separation, diet, and foraging scale.  相似文献   

14.
Imidazolinone-resistant winter wheat (Triticum aestivum L.) is being commercialized in the USA. This technology allows wheat growers to selectively control jointed goatgrass (Aegilops cylindrica Host), a weed that is especially problematic because of its close genetic relationship with wheat. However, the potential movement of the imidazolinone-resistance gene from winter wheat to jointed goatgrass is a concern. Winter wheat and jointed goatgrass have the D genome in common and can hybridize and backcross under natural field conditions. Since the imidazolinone-resistance gene (Imi1) is located on the D genome, it is possible for resistance to be transferred to jointed goatgrass via hybridization and backcrossing. To study the potential for gene movement, BC2S2 plants were produced artificially using imidazolinone-resistant winter wheat (cv. FS-4) as the female parent and a native jointed goatgrass collection as the male recurrent parent. FS-4, the jointed goatgrass collection, and 18 randomly selected BC2S2 populations were treated with imazamox. The percentage of survival was 100% for the FS-4, 0% for the jointed goatgrass collection and 6 BC2S2 populations, 40% or less for 2 BC2S2 populations, and 50% or greater for the remaining 10 BC2S2 populations. Chromosome counts in BC2S3 plants showed a restoration of the chromosome number of jointed goatgrass, with four out of four plants examined having 28 chromosomes. Sequencing of AHASL1D in BC2S3 plants derived from BC2S2-6 revealed the sexual transmission of Imi1 from FS-4 to jointed goatgrass. Imi1 conferred resistance to the imidazolinone herbicide imazamox, as shown by the in vitro assay for acetohydroxyacid synthase (AHAS) activity.  相似文献   

15.
How do the various anatomical parts (modules) of the animal body evolve into very different integrated forms (integration) yet still function properly without decreasing the individual’s survival? This long-standing question remains unanswered for multiple reasons, including lack of consensus about conceptual definitions and approaches, as well as a reasonable bias toward the study of hard tissues over soft tissues. A major difficulty concerns the non-trivial technical hurdles of addressing this problem, specifically the lack of quantitative tools to quantify and compare variation across multiple disparate anatomical parts and tissue types. In this paper we apply for the first time a powerful new quantitative tool, Anatomical Network Analysis (AnNA), to examine and compare in detail the musculoskeletal modularity and integration of normal and abnormal human upper and lower limbs. In contrast to other morphological methods, the strength of AnNA is that it allows efficient and direct empirical comparisons among body parts with even vastly different architectures (e.g. upper and lower limbs) and diverse or complex tissue composition (e.g. bones, cartilages and muscles), by quantifying the spatial organization of these parts—their topological patterns relative to each other—using tools borrowed from network theory. Our results reveal similarities between the skeletal networks of the normal newborn/adult upper limb vs. lower limb, with exception to the shoulder vs. pelvis. However, when muscles are included, the overall musculoskeletal network organization of the upper limb is strikingly different from that of the lower limb, particularly that of the more proximal structures of each limb. Importantly, the obtained data provide further evidence to be added to the vast amount of paleontological, gross anatomical, developmental, molecular and embryological data recently obtained that contradicts the long-standing dogma that the upper and lower limbs are serial homologues. In addition, the AnNA of the limbs of a trisomy 18 human fetus strongly supports Pere Alberch''s ill-named "logic of monsters" hypothesis, and contradicts the commonly accepted idea that birth defects often lead to lower integration (i.e. more parcellation) of anatomical structures.  相似文献   

16.
SUMMARY Cirripedes (barnacles) are crustaceans that are characterized by a very peculiar body plan, in particular by the lack of an abdomen. To study their body plan, we searched for their engrailed gene. We found two engrailed ( en.a/en.b ) genes in cirripedes. The two engrailed genes of the rhizocephalan barnacle Sacculina carcini are expressed in the posterior compartment of developing segments and appendages. When the neuroectoderm differentiates into epidermis and neuroderm the expression patterns of en.a and en.b diverge dramatically. en.a expression fades in segment epidermis whereas it is subsequently detected ventrally in reiterated putative neural cells. At the same time, en.b expression increases in the epidermis, which makes it a very good segmentation marker. Five tiny en.b stripes are observed between the sixth thoracic segment and the telson. We interpret these stripes as the molecular definition of vestigial abdominal segments, being the remnant of an ancestral state in keeping with the bodyplan of maxillopod crustaceans. engrailed expression is the first molecular evidence for a segmented abdomen in barnacles.  相似文献   

17.
Marine macroalgae (seaweed) show diverse life cycles. Species with a heteromorphic life cycle have a large multicellular algal body in one generation but have a very small body in the second generation of the same year. In contrast, the diploid and haploid life forms of isomorphic species have similar morphology, and these species often have more than two generations in a year. Here, we first study the optimal life cycle schedule of marine macroalgae when daily mortality changes seasonally, and then we discuss the conditions for coexistence and relative dominance of different life cycles. According to the optimal life cycle schedule, heteromorphic species tend to have a generation with a large algal body when mortality is low, and a microscopic-sized generation when mortality is high. In contrast, isomorphic species tend to mature when body size reaches a threshold value that is the same for different generations. We then examine the coexistence of the two life cycles when growth rate decreases with biomass. The model predicts that (1) at high latitudes (i.e., in strongly seasonal environments), heteromorphic species are likely to dominate over isomorphic species, and (2) species with a heteromorphic life cycle should dominate in the supratidal and upper intertidal zones where macroalgae tend to suffer high mortality, and also in the subtidal zone, where mortality is low, whereas isomorphic species are likely to be more successful when mortality is intermediate. These predictions are consistent with the observed distribution patterns of the two life cycles in macroalgae.  相似文献   

18.
Historians of science account the appearance of textbooks as an important step in the formation and consolidation of a new discipline. The texts of Park and Jordan were both very important in this light; however; they also can be used as a gauge of changing concepts within microbiology in the first four decades after its consolidation as a discipline, 1900-1940. This paper tracks these important texts and through them changing attitudes toward several important concepts: bacterial variation, human/bovine tuberculosis, and the existence of a non-symptomatic carrier state in infectious disease. The two texts are also compared regarding their view of microbes as pathogens vs. microbes as important and ubiquitous ecological agents.  相似文献   

19.
In the early twentieth century, the body was seen as both an ontogenetic and a phylogenetic entity. In the former case, its individual development, it was manifestly changeable, developing from embryo to maturity and thence to a state of decay. But in the latter case, concerning its development as a species, the question was an open one. Was its phylogenetic nature a stationary snapshot of the slow process of evolution, or was this too mutable? Historians have emphasised that the question of acquired inheritance remained open into the twentieth century; this paper explores how various constructions of the individual as a phylogenetic episode—a stage in the race’s evolution—related to representations of the body in the same period.A discussion of the work of the brothers Josef and Karel Čapek offers a contextualised answer to the question of bodily representation. Karel Čapek (1890–1938) explored the nature of the ‘average man’ through two different organisms, the robot and the amphibian, epitomes respectively of corporeal permanence and plasticity. Josef Čapek (1887–1945), along with other members of the Group of Plastic Artists, explored visual representations of the body that challenged cubist Bergsonian norms. In so doing, he affirmed what his brother also held: that despite the constrictions imposed by the oppressive political conditions in which the Czechs found themselves, the individual body was a fragile but fluid entity, capable of effecting change upon the future evolution of humankind.  相似文献   

20.
“To tell us that every Species of Things is endow'd with an occult specifick Quality by which it acts and produces manifest effects is to tell us nothing: But to derive two or three general Principles of Motion from Phenomena, and afterwards to tell us how the Properties and Actions of all corporeal Things follow from those manifest Principles, would be a very great step in Philosophy, though the Causes of these Principles were not yet discover'd.”  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号