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1.
Case Construction of Young Larvae of Micrasema longulum McL. (Trichoptera, Brachycentridae) The method of case building used by the first three larval instars of Micrasema longulum is described. The initial case is constructed above the hatching aperture in the jelly of the egg mass, in the same way as it is done by other species of Brachycentridae. The material of the initial case is caught from drifting particles in running water. From the end of the first larval instar only silk is used for the extension of the case. Two silken layers of a very regular pattern are to be distinguished. The construction of the cloverleaf-shaped posterior aperture is described. Some of the methods used for the case building show a maturing process during ontogenesis.  相似文献   

2.
Abstract

We present new results for thermodynamic properties and viscosities of pure dumbbell fluids, spherical/dumbbell mixtures, and dumbbell/dumbbell mixtures. It is evident that the interaction between dumbbell molecules is less attractive than that between spherical molecules which leads to lower viscosities. The shear viscosities and the LJ energies of both spherical Ar/dumbbell Kr (case B) and dumbbell Ar/dumbbell Kr (case C) are described quite well by the liquid mixture expression. The ideality in case C is much better than in case B which is consistent with the idea that dumbbell/dumbbell mixtures are likely to be more ideal than spherical/dumbbell mixtures. But the mixture pressures of the spherical/dumbbell mixture (case B) are described accurately by the ideal liquid mixture expression while those of the dumbbell/dumbbell mixture (case C) are not, which is not consistent with the better ideality of case C in the shear viscosity and the LJ energy than case B.  相似文献   

3.
We designed an interrupted case study to teach aerobic cellular respiration to major and nonmajor biology students. The case is based loosely on a real-life incident of rotenone poisoning. It places students in the role of a coroner who must determine the cause of death of the victim. The case is presented to the students in four parts. Each part is followed by discussion questions that the students answer in small groups prior to a classwide discussion. Successive parts of the case provide additional clues to the mystery and help the students focus on the physiological processes involved in aerobic respiration. Students learn the information required to solve the mystery by reading the course textbook prior to class, listening to short lectures interspersed throughout the case, and discussing the case in small groups. The case ends with small group discussions in which the students are given the names and specific molecular targets of other poisons of aerobic respiration and asked to determine which process (i.e., glycolysis, citric acid cycle, or the electron transport chain) the toxin disrupts.  相似文献   

4.
探讨应用电子阴道镜在寻找妊娠期阴道出血原因方面的价值。方法:对我院2004年5月-2006年11月64例非产科原因孕期阴道流血的孕妇,进行电子阴道镜检查及颈管分泌物培养和镜下定位活检。结果:阴道镜下发现宫颈赘生物12例,其中2例坏死,10例明显充血水肿;宫颈炎伴活动性出血2例,宫颈炎无活动性出血18例;正常宫颈16例;宫颈上皮内瘤样病变图象15例;宫颈分泌物培养阳性23例。结论:妊娠期不规则阴道出血原因复杂,阴道镜检查能较快排除与查明宫颈及阴道病变所导致的出血。  相似文献   

5.
We report a case of chimpanzee trisomy 22 in a captive-born female. Because chromosome 22 in great apes is homologous to human chromosome 21, the present case is analogous to human trisomy 21, also called Down syndrome. The chimpanzee in the present case experienced retarded growth; infantile cataract and vision problems, including nystagmus, strabismus, and keratoconus; congenital atrial septal defect; and hypodontia. All of these symptoms are common in human Down syndrome. This case was the second reported case of trisomy 22 in the chimpanzee. The chimpanzee in our case became blind by 7 years old, making social life with other chimpanzees difficult, but opportunities to interact with other conspecific individuals have been offered routinely. We believe that providing her with the best care over the course of her life will be essential.  相似文献   

6.
This paper discusses the Brazilian Supreme Court ruling on the case of anencephaly. In Brazil, abortion is a crime against the life of a fetus, and selective abortion of non-viable fetuses is prohibited. Following a paradigmatic case discussed by the Brazilian Supreme Court in 2004, the use of abortion was authorized in the case of a fetus with anencephaly. The objective of this paper is to analyze the ethical arguments of the case, in particular the strategy of avoiding the moral status of the fetus, the cornerstone thesis of the Catholic Church.  相似文献   

7.
The case series is the most prevalent type of clinical research in the plastic surgery literature. However, this is a lower level study design in the hierarchy of evidence. The case series is nevertheless a useful hypothesis generator for future studies. These in turn can be tested with more robust study designs such as the randomized controlled trial. Because the case series remains the most common study design used to communicate our new innovations, there is a need to improve its reporting so that readers will know why the study was undertaken, what the results were, and how the results affect patient care. The authors provide a guide to help future investigators improve the conduct and the reporting of their case series.  相似文献   

8.
Gurindji Kriol is a north Australian mixed language which combines lexical and structural elements from Gurindji (Pama-Nyungan), and Kriol (English-lexifier). One of the more striking features of the grammar of Gurindji Kriol is the presence of the Gurindji case paradigm including ergative and dative case-markers within a Kriol verbal frame. Given the fragility of inflectional morphology in other language contact situations, particularly contextual inflections such as structural case markers, this situation bears closer scrunity. This paper argues that the presence of Gurindji case morphology is the result of pervasive code-switching practices which immediately preceded the genesis of the mixed language. As the code-switching stabilised into a mixed language, case-marking was integrated into predicate argument structure of Gurindji Kriol via nominal adjunct structures. Yet, these case markers were not absorbed unscathed. Although the Gurindji Kriol case paradigm bears a close resemblance to its Gurindji source in form, these case markers have not been perfectly replicated in function and distribution. Contact with Kriol functional equivalents such as prepositions and word order have altered the function and distribution of these case markers. The last part of this paper examines the shift that has occurred in Gurindji-derived case morphology in Gurindji Kriol.  相似文献   

9.
The global flow equations of nonequilibrium thermodynamics for a single nonelectrolyte solute and water passing through a membrane are obtained by solving the local equations of motion. The method follows that developed for the general,n-solute case in the previous paper (Mikulecky, 1978). It is easily seen in this simple case that the passage from local interactions, formulated as position dependent frictional interactions in the equations of motion, to ghe global result involves a loss of any simple way of identifying particulars about local information. Two particular cases are analyzed in further detail: the case of no interaction within the pore and the case of constant interaction for both solute and solvent across the pore. In the former case, Onsager reciprocity survives in the global result if a self-consistent definition of the partial viscosity coefficients is used, while in the latter case, reciprocity is lost. Since, in many biologically interesting cases, the presence of interaction of the type considered here is likely to occur, the reciprocity condition should not automatically be assumed to hold.  相似文献   

10.
B G Tenchov 《Biofizika》1975,20(3):437-440
A theory of ionic transport through membranes in which the phospholipid molecules play the role of ion-carriers is developed. The transport of ions is accompanied by a membrane asymmetry. Expressions for stationary-state ion-fluxes in the case of one sort of ions transport, and in the case of coupled transport of ions of two sorts, are obtained. In the latter case near equilibrium the cross-coefficients are equal in accordance with Onsager's law. The possible role of phospholipids as ioncarriers in native membranes is discussed.  相似文献   

11.
A rare case of true median cleft of the upper lip associated with three skin masses is reported. While 114 cases of median cleft of the upper lip have been reported, in our literature review we found only 1 case, reported by Sharma, in which the median cleft was associated with skin masses. The embryology of this case is also discussed.  相似文献   

12.
The Wright-Fisher model is considered in the case where the population size is random and the magnitude of the selective advantage of one of the alleles varies with time. The central question addressed is the possibility of ultimate genetic polymorphism. Partial results are obtained in the general case and complete results in the case where the population size and selective advantage are not density dependent. Bounds on the fixation probability are obtained when the selective advantage is constant.  相似文献   

13.
The development of collateral circulation is a general vascular response which is well characterised in the heart. The most common precipitant of this is ischaemia and the most common manifestation is intra coronary collateralisation. Collateral flow between the heart and other thoracic structures is also documented albeit rarely and can be congenital or acquired. In this case report we define a unique case of collateral flow between the coronary and pulmonary circulations in a complex case of mediastinal fibrosis.  相似文献   

14.
The case of industrial melanism in the peppered moth has been used as a teaching example of Darwinian natural selection in action for half a century. However, over the last decade, this case has come under attack from those who oppose Darwinian evolution. Here, the main elements of the case are outlined and the reasons that the peppered moth case became the most cited example of Darwinian evolution in action are described. Four categories of criticism of the case are then evaluated. Criticisms of experimental work in the 1950s that centered on lack of knowledge of the behavior and ecology of the moth, poor experimental procedure, or artificiality in experiments have been addressed in subsequent work. Some criticisms of the work are shown to be the result of lack of understanding of evolutionary genetics and ecological entomology on the part of the critics. Accusations of data fudging and scientific fraud in the case are found to be vacuous. The conclusion from this analysis of criticisms of the case is that industrial melanism in the peppered moth is still one of the clearest and most easily understood examples of Darwinian evolution in action and that it should be taught as such in biology classes.  相似文献   

15.
The dogfish egg case is a composite structure that combines mechanical tensile strength, toughness and elasticity with high permeability to small molecules and ions. Presumably, it provides both a protective and a filtering role for the egg/embryo contained within it. In this work, we performed structural studies of the Galeus melastomus egg case at two different stages of the hardening process, utilizing ATR FT-IR and FT-Raman spectroscopy. Based on these data we deduce that: (a) The G. melastomus egg case, in close analogy to that of the related species Scyliorhinus cunicula, is a complex, composite structure which consists mainly of an analogue of collagen IV. This network forming protein appears to have common secondary structural characteristics in the entire egg case. (b) The outermost layer of the non-sclerotized egg case is especially rich in tyrosine, while the innermost layer is rich in polysaccharides, presumably glycosaminoglycans, and lipids. These differences are diminished upon hardening. (c) Disulfide bonds do not appear to play a significant role in cross-linking. However, cross-links involving tyrosine residues appear to sclerotize the egg case. It is proposed that the intensity of the Raman band at ca. 1615 cm(-1), which is due to ring stretching vibrations of Tyr, might be a useful indicator of the sclerotization status of a certain proteinaceous tissue, when tyrosines are involved in sclerotization mechanisms.  相似文献   

16.
Abstract: The software tool ecosolvent is presented that allows for comparative environmental assessment of treatment technologies for specific, user-defined, waste-solvent mixtures. The tool is composed of models for waste-solvent distillation as well as for thermal treatment in hazardous waste-solvent incinerators and cement kilns. It was designed with a tiered structure in order to allow for a high flexibility regarding informational needs. The life-cycle assessment method was used to assess the environmental impact. The applicability of the tool is shown with two case studies from industry. In these case studies, various waste-solvent treatment technologies are compared for two specific waste-solvent mixtures. Potential use of the ecosolvent tool for its role in practical decision making in chemicals industries is illustrated by two case studies of waste-solvent systems. In the ethyl acetate case study, the tool indicates that solvent recovery by distillation is clearly better than incineration of the waste solvent. The results from the methanol case study are less clear-cut. In the subsequent article (part II), the ecosolvent tool will be used to derive general rules of thumb and specific recommendations for 45 important solvents used in chemical industries. Additionally, a framework will be presented that provides quick and easy decision support regarding environmentally optimized waste-solvent management.  相似文献   

17.
A recently introduced approximation method is applied in order to obtain an expression for the amount of a substance remaining within a nerve at any time, the nerve having been soaked for a long time in a solution containing the substance until the time zero when it is bathed in the same solution but without the substance. The case of a uniform nerve without a sheath leads to substantially the same results as previously obtained by A. V. Hill (1928) for this case. A solution is given for the case of a nerve without sheath but having fibers which are permeable. In this case it is shown how an effective diffusion coefficient for the interstitial fluid can be obtained, as well as the effective inward and outward fiber permeabilities. A solution is given for the case of a nerve with a sheath in which the substance considered does not penetrate the fibers, and it is shown how the effective diffusion coefficients of the sheath and the interstitial fluid can be obtained.  相似文献   

18.
结合激光雷达分析上海地区一次连续浮尘天气过程   总被引:4,自引:0,他引:4  
马井会  顾松强  陈敏  施红  张国琏 《生态学报》2012,32(4):1085-1096
通过分析2010年3月至20日至3月22日上海地区一次典型的连续浮尘天气过程,利用激光雷达数据资料反演得到的气溶胶消光系数图和垂直廓线图,结合地面气象数据和气溶胶观测资料以及卫星遥感资料,初步得出了此次连续浮尘天气形成的原因。外源性输入和垂直风场分布是导致此次浮尘天气发生的重要原因,大气层结变化决定着浮尘天气发生的强度,当存在接地逆温时,浮尘天气维持,而太阳辐射强度变化决定着边界层高度的变化。第一次浮尘过程以大颗粒污染为主,且在消光作用中散射性气溶胶的贡献大于吸收性气溶胶,而第二次回流浮尘过程则PM2.5比重上升,吸收性气溶胶对消光系数的贡献与散射性气溶胶大体相当。  相似文献   

19.
Summary We have previously detected a single base substitution of G by A at the Arg codon CGC in exon 4 of the mutant lactate dehydrogenase (LDH) gene, an unstable LDH-B variant (case 1). Here, we use the polymerase chain reaction (PCR) to amplify genomic DNA of two cases (the original case 1 and a new patient, case 2). We were able to confirm that case 1 is homozygous for the mutation, causing a replacement of the conserved Arg by His at residue 173. The resulting LDH-B variant subunit is unstable in vivo. Whereas the mutation in exon 4 was not observed in case 2, a different single base substitution of A by C was detected at the Ser codon AGT in exon 3. This mutation causes a replacement of the conserved Ser by Arg at residue 131. Genomic analysis of the family of case 2 by mismatched PCR showed that the missense mutation was consistent with their biochemical phenotypes. The replacement results in a conformational change of the residues near the Ser, probably because the side chain of Arg is much more bulky than that of Ser. The change may affect the arrangement of the cofactor binding site and result in the loss of enzyme activity. The experimental observations are consistent with computer graphics analyses.  相似文献   

20.
The Nernst-Planck continuum equation for a channel that can be occupied by at most two ions is solved for two different physical cases. The first case is for the assumption that the water and ion cannot get around each other anywhere in the channel, so that if there are two ions in the channel the distance between them is fixed by the number of water molecules between them. The second case is for the assumption that there are regions at he ends of the channel where the ions and water can get around each other. For these two cases, the validity of the simple two-site reaction-rate approximation when there is a continuously varying central energy barrier was evaluated by comparing it with the exact Nernst-Planck solution. For the first continuum case, the kinetics for the continuum and reaction-rate models are nearly identical. For the second case, the agreement depends on the strength of the ion-ion interaction energy. For a low interaction energy (large channel diameter) a high ion concentrations, there is a large difference in the flux as a function of voltage for the two models-with the continuum flux becoming more than four times larger at 250 mV. Simple analytical expressions are derived for the two-ion continuum channel for the case where the ends are in equilibrium with the bulk solution and for the case where ion mobility becomes zero when there are two ions in the channel. The implications of these results for biological channels are discussed.  相似文献   

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