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1.
In the past, body mass was reconstructed from hominin skeletal remains using both "mechanical" methods which rely on the support of body mass by weight-bearing skeletal elements, and "morphometric" methods which reconstruct body mass through direct assessment of body size and shape. A previous comparison of two such techniques, using femoral head breadth (mechanical) and stature and bi-iliac breadth (morphometric), indicated a good general correspondence between them (Ruff et al. [1997] Nature 387:173-176). However, the two techniques were never systematically compared across a large group of modern humans of diverse body form. This study incorporates skeletal measures taken from 1,173 Holocene adult individuals, representing diverse geographic origins, body sizes, and body shapes. Femoral head breadth, bi-iliac breadth (after pelvic rearticulation), and long bone lengths were measured on each individual. Statures were estimated from long bone lengths using appropriate reference samples. Body masses were calculated using three available femoral head breadth (FH) formulae and the stature/bi-iliac breadth (STBIB) formula, and compared. All methods yielded similar results. Correlations between FH estimates and STBIB estimates are 0.74-0.81. Slight differences in results between the three FH estimates can be attributed to sampling differences in the original reference samples, and in particular, the body-size ranges included in those samples. There is no evidence for systematic differences in results due to differences in body proportions. Since the STBIB method was validated on other samples, and the FH methods produced similar estimates, this argues that either may be applied to skeletal remains with some confidence.  相似文献   

2.
The " A" - " Not A" method is a rating method with two categories. It is often treated as a discrimination method. Unlike forced choice procedures, the Thurstonian model for this method involves a choice criterion. In statistical tests, it is treated as a comparison of two proportions. In this paper, the power for hypothesis tests involving the monadic and replicated monadic " A" - " Not A" method is discussed. The power functions and the sample sizes needed for 80% power are given based on Thurstone's δ. Designs with equal and unequal allocations for A and A (Not A) samples are considered. The power of the method is also compared with that of four forced choice methods under the assumption that the perceptual variance is identical among methods. The comparison shows that, in general, the power for the five methods ranks from high to low: the 3-AFC, 2-AFC, " A" - " Not A", triangular and duo-trio. The comparison also shows that, based on the same number of panelists and/or the same sample size for the A and A samples for the methods, if the panelists are not too discrepant and the choice criterion in the " A" - " Not A" method is not too strict or too lax, the power of the " A" - " Not A" method is very close to that of the 2-AFC method.  相似文献   

3.
The review deals with the data of literature on the role of the "quorum sensing" (QS) system ensuring the social behavior of bacteria in the regulation of virulence genes. The mechanisms of the action of these systems in Gram-negative and Gram-positive bacteria, as well as the influence of acyl-homoserine lactones, one of the components of the QS system, on the immune response of the infected host are discussed. In addition, in this review the data of literature on the existence of bacteria in the form of biofilms are presented. The methods of the identification of biofilms, the methods of their experimental preparation and the role of the QS system in the process of their formation are considered.  相似文献   

4.
The unprecedented advances in molecular biology during the last two decades have resulted in a dramatic increase in knowledge about gene structure and function, an immense database of genetic sequence information, and an impressive set of efficient new technologies for monitoring genetic sequences, genetic variation, and global functional gene expression. These advances have led to a new sub-discipline of toxicology: "toxicogenomics". We define toxicogenomics as "the study of the relationship between the structure and activity of the genome (the cellular complement of genes) and the adverse biological effects of exogenous agents". This broad definition encompasses most of the variations in the current usage of this term, and in its broadest sense includes studies of the cellular products controlled by the genome (messenger RNAs, proteins, metabolites, etc.). The new "global" methods of measuring families of cellular molecules, such as RNA, proteins, and intermediary metabolites have been termed "-omic" technologies, based on their ability to characterize all, or most, members of a family of molecules in a single analysis. With these new tools, we can now obtain complete assessments of the functional activity of biochemical pathways, and of the structural genetic (sequence) differences among individuals and species, that were previously unattainable. These powerful new methods of high-throughput and multi-endpoint analysis include gene expression arrays that will soon permit the simultaneous measurement of the expression of all human genes on a single "chip". Likewise, there are powerful new methods for protein analysis (proteomics: the study of the complement of proteins in the cell) and for analysis of cellular small molecules (metabonomics: the study of the cellular metabolites formed and degraded under genetic control). This will likely be extended in the near future to other important classes of biomolecules such as lipids, carbohydrates, etc. These assays provide a general capability for global assessment of many classes of cellular molecules, providing new approaches to assessing functional cellular alterations. These new methods have already facilitated significant advances in our understanding of the molecular responses to cell and tissue damage, and of perturbations in functional cellular systems.As a result of this rapidly changing scientific environment, regulatory and industrial toxicology practice is poised to undergo dramatic change during the next decade. These advances present exciting opportunities for improved methods of identifying and evaluating potential human and environmental toxicants, and of monitoring the effects of exposures to these toxicants. These advances also present distinct challenges. For example, the significance of specific changes and the performance characteristics of new methods must be fully understood to avoid misinterpretation of data that could lead to inappropriate conclusions about the toxicity of a chemical or a mechanism of action. We discuss the likely impact of these advances on the fields of general and genetic toxicology, and risk assessment. We anticipate that these new technologies will (1) lead to new families of biomarkers that permit characterization and efficient monitoring of cellular perturbations, (2) provide an increased understanding of the influence of genetic variation on toxicological outcomes, and (3) allow definition of environmental causes of genetic alterations and their relationship to human disease. The broad application of these new approaches will likely erase the current distinctions among the fields of toxicology, pathology, genetic toxicology, and molecular genetics. Instead, a new integrated approach will likely emerge that involves a comprehensive understanding of genetic control of cellular functions, and of cellular responses to alterations in normal molecular structure and function.  相似文献   

5.
目的:研究中药复方“生发灵215”的两种提取方法和生发作用.方法:参考该中药复方的传统临床应用,考察了该复方的两种提取方法:一是用油提取直接涂抹的传统方法,一是用醇提法并制成软膏剂.然后用两种提取物对试验兔进行皮肤刺激性实验和促毛发生长作用的初步探讨.结果:软膏剂在外观、手感以及使用舒适度方面均大大优于传统的油提取物.皮肤刺激实验表明油提物对完整皮肤和破损皮肤均有刺激性,而通过醇提物制备的软膏制剂作用温和,没有发现明显的刺激性.毛发生长实验表明,醇提物制备的软膏制剂在促毛发生长效果方面和油提物没有明显差异.结论:醇提物制成的软膏剂具有良好的临床应用价值.  相似文献   

6.
The use of complementary methods to animal experiments is very old. Spallanzani (1785) apparently was the first who used such methods in his studies on digestion. In the 19th century Eberle, Pappenheim, Purkyné and others used on their studies on the process of digestion artificial chyme. On this view, Beaumont published in 1834 an interesting paper on the digestion of men after observations in vivo and parallel in vitro. All papers show, that the using of complementary methods to animal experiments was not unusual in the 19th century.  相似文献   

7.
Inversion of the pericentromeric region of human chromosome 3 [inv (3) (p11q11.2)] is a rare event. Initially, this inversion was identified with staining for Q-bands by fluorescence using quinacrine (QFQ) and later characterized with staining for C-bands by CBG technique. The molecular methods of fluorescence in situ hybridization (FISH) and AluI/Giemsa and TaqI/Giemsa techniques were utilized. The findings suggest that the variable band q11.2 on chromosome 3 contains alphoid DNA sequences, which appear to be similar to those identified by conventional methods in the centromeric region (band p11).  相似文献   

8.
传统的环境工程微生物学实验在教学内容方面多是一些操作性和验证性的实验,在教学手段上多采用灌输式被动教学,这些教学内容和教学方式极大的抑制了学生的自主创新能力。作者结合自己的教学改革实践,以培养学生的自主创新兴趣和能力为目标,对环境工程微生物学实验进行了一系列教学改革尝试,并取得了良好的结果。在总结教学改革实践的基础上,从优化实验教学内容和改进教学方法两个方面进行系统阐述。  相似文献   

9.
"PCR-karyotype" of human chromosomes in somatic cell hybrids   总被引:4,自引:0,他引:4  
Amplification of human DNA sequences in 16 monochromosomal somatic cell hybrids containing different human chromosomes were performed by the polymerase chain reaction (PCR) using primer directed at human-specific regions of Alu or L1, the two major classes of interspersed repetitive sequences (IRS-PCR). A chromosome-specific pattern of amplification products was observed on agarose gels run with ethidium bromide, producing a "PCR-karyotype." This simple gel analysis provides a rapid method for identifying and monitoring the human chromosomal content of monochromosomal somatic cell hybrids without conventional cytogenetic analysis. Hybrids containing multiple human chromosome produce complex gel patterns, but identification of chromosome content can be achieved by hybridization of PCR products against a reference panel of monochromosomal or highly reduced hybrids representing each human chromosome. This dot-blot method also enables identification of human marker chromosomes or translocated pieces in hybrids that are not identifiable by cytogenetic methods. These IRS-PCR methods should greatly reduce the need for more laborious cytogenetic, isozyme, and Southern blot characterizations of human-rodent cell hybrids.  相似文献   

10.
During the 1st International Meeting on "Stem Cell Applications in the Craniofacial Region" promoted in Naples (Italy), invited researchers presented theirwork and the most innovative methods regarding stem cells (SCs) and their application to the craniofacial region of the human body. In addition, some researchers showed their case-reports on craniofacial reconstruction using either osteo-distraction or reconstruction surgical methods. The aim of this biannual meeting is to stimulate discussion, improve knowledge and promote scientific collaboration among basic and clinical scientists in the main topics of SC use in therapy. A summary of this meeting is given.  相似文献   

11.
The repeatability coefficient of sire evaluation by daughters performance in different lactations was 0.38-0.70, that suggests the necessity to specify annually the previous sire evaluation on receiving new daughters performance data. When using the "daughters-mothers" method the repeatability coefficients of sire evaluation by dairy indexes, milk fat content and total milk fat production (0.41, 0.52 and 0.45 respectively) were significantly higher than those obtained by the "daughters-herdmates" method (0.25, 0.30 and 0.28 respectively). Thus, sire progeny testing evaluation should be carried out simultaneously by both methods. Nevertheless, the "daughters-mothers" method is preferable.  相似文献   

12.
The identification of over 500 protein kinases encoded by the human genome sequence offers one measure of the importance of protein kinase networks in cell biology. High throughput technologies for inactivating genes are producing an awe-inspiring amount of data on the cellular and organismal effects of reducing the levels of individual protein kinases. Despite these technical advances, our understanding of kinase networks remains imprecise. Major challenges include correctly assigning kinases to particular networks, understanding how they are regulated, and identifying the relevant in vivo substrates. Genetic methods provide a way of addressing these questions, but their application requires understanding the nuances of how different types of mutations can affect protein kinases. The goal of this article is to provide a brief introductory primer into these issues using examples from yeast MAPK cascades and to motivate future systematic genetic analysis focusing on individual residues of protein kinases.  相似文献   

13.
Among the mononudear cells which participate in the different immunological mechanisms of cell destruction, the "K-cells" can induce in man, rat and mouse a cytotoxicity cell mediated depending on IgG type antibodies. Utilizing methods based on research works in man we were able to detect the presence of this K-cell in the peripheral blood of dogs.  相似文献   

14.
15.
The synthesis of the tetradecapeptide somatostatin (somatotropin release inhibiting factor, SRIF) by conventional methods of peptide synthesis is described. The synthetic material was found to be biologically active at the pico-gram/ml dose level.  相似文献   

16.
根据研究生教学特点,为适应肠道菌群与人类疾病关系研究成为新研究热点与前沿的形势,对其无菌动物与微生态学专题教学进行改革实践。根据菌群与疾病关系研究的最新研究进展、研究生科研能力培养规律,在研究生《医学实验动物学》课程的无菌动物与微生态学专题教学中设置微生态学理论与研究技术简介、无菌动物培育原理及特点、无菌动物实验设计方法、国内外无菌动物资源简介等4部分内容。力争紧跟学科发展动态,强调知识的前沿性、实用性、综合性和交叉性,促进研究生课题设计能力培养和科研思路的开拓,创建研究生无菌动物与微生态学专题教学的新模式。  相似文献   

17.
Although in contemporary methods and (insofar as we are justified in using the term at all) in the contemporary psychology of foreign-language learning, the concepts of "active" and "passive" are widely used with reference to aspects of learning, to methods, habits, and models, these concepts are actually quite vague. This raises the necessity of systematically examining the main problems associated with maintaining a distinction between "active" and "passive" in language acquisition.  相似文献   

18.
I.P. Pavlov considered consciousness as an area of optimum excitability moving over the human cerebral cortex depending on the character of performed mental activity. Contemporary methods of computer analysis of electrical activity and brain thermal production have allowed to turn this metaphor into experimentally observed reality. It is shown that preservation of connections of cortical gnostic zones with verbal structures of the left hemisphere is the obligatory condition for consciousness functioning. These data reinforce the determination of consciousness as operation with knowledge, which by means of words, mathematic symbols and art images can be transmitted to other people. Communicative origin of consciousness creates possibility of mental dialogue with oneself, i.e. leads to the appearance of self-consciousness of the personality.  相似文献   

19.
Turner JR 《Genetics》1981,99(2):365-369
THE CHANGE IN MEAN FITNESS FOR TWO LOCI UNDER SELECTION CAN BE DESCRIBED BY FOUR TERMS: (i) the variance of fitness, (ii) a weighted between-gamete covariance, (iii) a function of recombination, linkage disequilibrium and the slope of the surface of mean fitness on disequilibrium, and (iv) a function of these two parameters and the curvature of the surface. Independent derivations of this equation by different methods, although thought at one time to be in disagreement, give algebraically identical results.  相似文献   

20.
A method and an apparatus that reduce the heavy expenses involved in traditional methods for the large-scale monolayer production of primary and secondary, strain and line cells and of the biologicals derived therefrom are described. The method is based on the principle of gathering in a single unit a sheaf of columns by means of general manifolds fitted with cocks. The growth of cells on the glass walls is irrespective of the number, length, and diameter of the columns used. The apparatus, placed in a thermo-adjustable room and connected to adequate devices which allow it to rotate on its longitudinal axis and to be set in a vertical position, need not be dismounted nor transported since it can be connected by a number of tubes to the necessary services. Sterilization is carried out by flowing steam and fluids are poured in or drained off by vacuum or pressure. A microscope fitted to the bearing structure allows the operator to observe the cell monolayers and the cytopathic effect of viruses on the whole length of the outer columns. During the various working stages pH is under continuous control and automatically adjusted. The whole working cycle is extensively described (cleaning, sterilization, seeding, incubation, trypsinization of the monolayer, culture and harvesting of the virus) and results compared with those obtained by traditional methods.  相似文献   

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