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1.
The total support index (Bremer, 1994), a measure of cladogram support, is influenced both by character incongruence and by uninformative characters. A modified version of this index is therefore proposed—the proportional support index. This index measures the actual support for a cladogram relative to the maximum potential support as determined by the number of informative characters. This index is not distorted by uninformative characters and is thus a more accurate means to compare the strength of phylogenetic signals in different data sets.  相似文献   

2.
The adsorption of aluminum ions by Saccharomyces cerevisiae has been investigated by determining adsorption isotherms and electrophoretic mobility. The adsorption of aluminum ensures a neutralization of the cell surface charge and allows adhesion of the cells to glass and polycarbonate. Glass slides have been taken as a negatively charged model support, allowing the authors to study in detail the process of adhesion. The cells are simply pretreated by an aluminum solution near pH 4. Bringing the Al-pretreated cells in contact with the support by sedimentation and washing the support and sediment makes it possible to obtain a single, dense, regular layer of cells adhering strongly to the support. Adhesion can also be obtained from a suspension flowing parallel to a vertical support, provided the flow velocity is sufficiently small; the amount of cells immobilized per unit support area is about one-half that obtained by sedimentation. The immobilized cells show a specific activity for ethanol production from glucose which is similar to cells in suspension.  相似文献   

3.
The properties of a new and commercially available amino-epoxy support (amino-epoxy-Sepabeads) have been compared to conventional epoxy supports to immobilize enzymes, using the beta-galactosidase from Aspergillus oryzae as a model enzyme. The new support has a layer of epoxy groups over a layer of ethylenediamine that is covalently bound to the support. This support has both a great anionic exchanger strength and a high density of epoxy groups. Epoxy supports require the physical adsorption of the proteins onto the support before the covalent binding of the enzyme to the epoxy groups. Using conventional supports the immobilization rate is slow, because the adsorption is of hydrophobic nature, and immobilization must be performed using high ionic strength (over 0.5 M sodium phosphate) and a support with a fairly hydrophobic nature. Using the new support, immobilization may be performed at moderately low ionic strength, it occurs very rapidly, and it is not necessary to use a hydrophobic support. Therefore, this support should be specially recommended for immobilization of enzymes that cannot be submitted to high ionic strength. Also, both supports may be expected to yield different orientations of the proteins on the support, and that may result in some advantages in specific cases. For example, the model enzyme became almost fully inactivated when using the conventional support, while it exhibited an almost intact activity after immobilization on the new support. Furthermore, enzyme stability was significantly improved by the immobilization on this support (by more than a 12-fold factor), suggesting the promotion of some multipoint covalent attachment between the enzyme and the support (in fact the enzyme adsorbed on an equivalent cationic support without epoxy groups was even slightly less stable than the soluble enzyme).  相似文献   

4.
We studied received social support using the cross-cultural method of situation sampling. College students from the US and Japan described and rated recent examples of received social support, both everyday support as well as support in response to stress. Middle class, European-American (EuA) students’ situations fit a model in which support is frequent and offered freely in interactions, even for relatively minor issues. Even when it’s unrequested, EuA support makes recipients feel in control, and support-givers are perceived to have acted by free choice. In contrast, results suggest that middle-class Japanese (Jpn) contexts favor support that is empathic and responsive to the recipients’ degree of need. Japanese support was experienced positively when it was emotional support, when it was in more serious situations and when the support was rated as needed by the recipient. In Japan, although problem-based support is most common, it is not particularly positive, apparently because it is less likely to be perceived as needed.  相似文献   

5.
A new support was prepared by the combination of an oxygen enrichment hollow fiber membrane and fibrous support for immobilization of activated sludge microorganisms. A biofilm of activated sludges immobilized and grown on the support were shown to be highly active. It was confirmed that a wastewater treatment method using this new support was efficient for TOC and TN removal.  相似文献   

6.
Improvements to resampling measures of group support   总被引:4,自引:0,他引:4  
Several aspects of current resampling methods to assess group support are reviewed. When the characters have different prior weights or some state transformation costs are different, the frequencies under either bootstrapping or jackknifing can be distorted, producing either under‐ or overestimations of the actual group support. This is avoided by symmetric resampling, where the probability p of increasing the weight of a character equals the probability of decreasing it. Problems with interpreting absolute group frequencies as a measure of the support are discussed; group support does not necessarily vary with the frequency itself, since in some cases groups with positive support may have much lower frequencies than groups with no support at all. Three possible solutions for this problem are suggested. The first is measuring the support as the difference in frequency between the group and its most frequent contradictory group. The second is calculating frequencies for values of p below the threshold under which the frequency ranks the groups in the right order of support (this threshold may vary from data set to data set). The third is estimating the support by using the slope of the frequency as a function of different (low) values of p; when p is low, groups with actual support have negative slopes (closer to 0 when the support is higher), and groups with no support have positive slopes (larger when evidence for and against the group is more abundant).  相似文献   

7.
A mineral support was used for cephamycin C production in a culture using soybean oil as the sole carbon source. When the support was added into an oil-water system, the soybean oil was emulsified as fine oil droplets, which was observed by a photomicroscope. Mycelia were also twined around the support, which was observed by a scanning electron microscope. That caused the formation of an oil-mycelia complex on or around the support, which provided a larger specific surface area of oil. When 15 g/L of the support was used in a batch culture of Streptomyces sp. P6621 with 50 g/L of soybean oil, the maximum cephamycin C concentration was 2.8 g/L, which was 2.2 times higher than that without the support. This indicates that the mineral support is useful for the culture system using vegetable oil as a carbon source. (c) 1997 John Wiley & Sons, Inc.  相似文献   

8.
A study of research funding at Memorial University's Marine Sciences Research Laboratory shows that true costs far exceed support from grants and contracts alone. Research grant levels have to be matched by a similar level of support for infrastructure, and other university-supplied support (mostly salaries) may amount to twice that supplied by grants. Faced with declining external support for general infrastructure, universities can ill afford to become involved in scientific mega-projects. There is little evidence that increased funding enhances productivity.  相似文献   

9.
N-vinylpyrrolidone-N(2-hydroxy) acrylamide copolymer-modified porous glass was studied as a support for gel permeation chromatography. Influenza, Sendai, fowl plague viruses and rota-viruses were purified by chromatography on the support. As compared with Sepharose 4B the support shows better hydrodynamic properties and yields higher amounts of purified viruses. The support can be also applied to the t-RNA and ribosomes separation.  相似文献   

10.
The vocal behavior of threat calls was investigated in a captive group of Japanese monkeys (Macaca fuscata fuscata). The vocalizations were heard most often when they undertook winner-support during triadic agonistic interactions. The likelihood of call emission in support of the winner was affected by the attributes of the participants, and not by the types of agonistic behavior. The calls were emitted by intermediate ranking animals frequently in support of high ranking animals and in support of females. The calling behavior of winner-supporters appears to advertise the partner and distant group members of their support for reciprocation in the near future.  相似文献   

11.
Optimal operation condition was investigated for immobilized rice callus culture using a turbine blade reactor (TBR2) with polyurethane foam supports. By using polyurethane foam block as immobilization support, the inhibition of cell growth at a high agitation speed was avoided because the hydrodynamic stress against immobilized cell was probably reduced. Experimental results in each operational condition were assessed by means of rice callus growth, immobilization ratio in TBR and those regeneration frequencies in regeneration culture using solid medium. Concerning with pore size of polyurethane foam and support size, three-millimeter cube support of polyurethane foam with an average pore size of 1.3 mm was the most suitable support. The maximum immobilization ratio was 50% under 5% support volume by volume of growth medium. For improving the immobilization ratio of rice callus in the TBR, the optimum TBR operation and modification were investigated further. By repeating a periodic operation 3 times (agitating at 300 rpm for 5 min and then 50 rpm for 2 min, and then 200 rpm of constant agitation speed during the remaining time), almost all supports could entrap rice callus and homogeneous immobilization was attained. The immobilization ratio was improved as compared with that using a constant operation at 200 rpm. Next, the TBR was modified by setting an air sparger inside the stainless mesh cylinder. In the modified TBR, the floating support by air bubbles was reduced, and the immobilization ratio increased further and reached 86.3% when we increased the support volume to 15% under periodic operation on a daily basis. The regeneration frequency of immobilized callus was also slightly increased by periodic operation and modification of the TBR.  相似文献   

12.
A highly flexible, mechanically and chemically stable copolymer, tri(propylene glycol) glycerolate diacrylate cross-linked polystyrene (PS-TRPGGDA), was synthesized by the suspension polymerization and employed as a solid support for peptide synthesis. The beaded polymer support containing secondary hydroxyl functional groups in the cross-linker was used as the growth site for peptide synthesis. The procedure is unique and cost-effective in that it avoids the initial functionalization steps required for most of the styrene-based polymer supports. The resin was characterized by 13C-CP-MAS NMR spectroscopy and the morphologic features of the resin were investigated using scanning electron microscopy. Swelling studies conducted on the new support revealed that the PS-TRPGGDA resin undergoes more effective swelling and solvation than PS-DVB resin in all solvents used in peptide synthesis. The efficiency of the new support was demonstrated by synthesizing a 'difficult' sequence Ala-Arg-(Ala)6-Lys and comparing it with commercially available Merrifield and Sheppard resins. The synthetic efficiency was further demonstrated by the synthesis of a 24-residue NR 2A peptide substrate of calcium/calmodulin-binding peptide. The high yield and purity of the peptide synthesized on the novel support indicates the positive role of the flexible and hydrophilic cross-linking agent in the solid support.  相似文献   

13.
The ankle plantar flexor muscles, gastrocnemius (Gas) and soleus (Sol), have been shown to play important roles in providing body support and forward propulsion during human walking. However, there has been disagreement about the relative contributions of Gas and Sol to these functional tasks. In this study, using independent manipulations of body weight and body mass, we examined the relative contribution of the individual plantar flexors to support and propulsion. We hypothesized that Gas and Sol contribute to body support, whereas Sol is the primary contributor to forward trunk propulsion. We tested this hypothesis by measuring muscle activity while experimentally manipulating body weight and mass by 1) decreasing body weight using a weight support system, 2) increasing body mass alone using a combination of equal added trunk load and weight support, and 3) increasing trunk loads (increasing body weight and mass). The rationale for this study was that muscles that provide body support would be sensitive to changes in body weight, whereas muscles that provide forward propulsion would be sensitive to changes in body mass. Gas activity increased with added loads and decreased with weight support but showed only a small increase relative to control trials when mass alone was increased. Sol activity showed a similar increase with added loads and with added mass alone and decreased in early stance with weight support. Therefore, we accepted the hypothesis that Sol and Gas contribute to body support, whereas Sol is the primary contributor to forward trunk propulsion.  相似文献   

14.
Results of experimental studies are reviewed that point out to the leading role of the support afferents in control of structural-functional properties of the tonic muscle system. It is shown that the support afferents play a role of the trigger in the postural system, the trigger enhancing (when the support is present) or inhibiting (when the support is withdrawn) the activity of tonic motor units (MU's). Under the absence of support condition, recorded in extensors are: an obvious decline of the muscle stiffness and the maximal voluntary force; a significant decrease of the absolute force of the isometric contraction of single skin muscle fibers evoked by Ca++; a prominent decline of the tonic muscle fibers transversal size; and the transformation of the myosin phenotype from slow to fast one. Mechanical stimulation of the support zones of soles in the regimes of locomotion (slow and fast stepping) under the absence of support condition eliminates all the above effects.  相似文献   

15.
Rapid synthesis of oligodeoxyribonucleotides is described by a solid phase method. Polysterene grafted on the surface of polytetrafluoroethylene has been found to be an adequate support. The properties of the support were studied in the synthesis of a number of oligonucleotides 6 to 15 nucleotides long. A flow-type semi-automatic synthesizer has been used. Each nucleotide addition involves seven steps and takes 8 hours. Oligonucleotide isolated and purified by ion-exchange chromatography amounts to 1-3 mumol per gram of support.  相似文献   

16.
Variation of biological populations is required for evolution by natural selection, and variance is a fundamental component in quantitative characterization of evolutionary differences and rates of change. Biological variation is widely understood to be normally distributed because of a general theoretical law of error. The law of error has two forms, and resulting normality may be arithmetic-where equivalent positive and negative deviations from expectation differ by equal amounts, or normality may be geometric-where equivalent deviations differ by equal proportions. Which law of error applies in biology can only be determined empirically, and this is surprisingly difficult. A new likelihood approach is developed here using data from anthropometric surveys of humans in two states in India: Maharashtra and Uttar Pradesh. Each state sample is large, but more importantly, each includes a large number of smaller subsamples. Likelihood support is additive, and subsamples are advantageous because (1) they are more homogeneous, (2) they yield probabilities and support scores in every case, and (3) significance can be evaluated first by tracing signs of the subsample support scores and then by comparing subsample support sums. Sign traces that fluctuate randomly show arithmetic and geometric normality to be indistinguishable. Two of 14 measurement variables studied here have subsample support sign traces differing from random, and one is significant in having a subsample support sum falling outside a 95% prediction interval for the 12 fluctuating traces: geometric normality is favored by a factor of ca. 10(60). Six of 14 index variables have support sign traces differing from random, and all are significant in having subsample support sums falling outside a 95 % prediction interval for the 8 fluctuating traces: geometric normality is favored by factors of 10(8) or more. Arithmetic and geometric normality cannot be distinguished for 21 of 28 variables studied here, but whenever alternatives are distinguishable geometric normality is consistently and strongly favored. This means that the applicable law of errors is proportional. In practical terms, arithmetic measurements must be transformed using logarithms to represent both the geometric normality of biological variation and the relative functional significance of measurements appropriately.  相似文献   

17.
Breastfeeding is one important form of maternal investment that is influenced by support from kin and non-kin. This paper investigates who provides support for breastfeeding mothers and their children, what type of support they provide, and how support impacts breastfeeding duration. The data were derived from a survey of 594 American mothers and were analyzed using quantitative methods, including Cox regression. Analyses indicate that mothers receive significant support, particularly from spouses and maternal grandmothers. More frequent breastfeeding discussions with La Leche League and maternal grandfathers were associated with longer duration, whereas discussions with physicians were associated with shorter breastfeeding duration. Results indicate that consulting others specifically about breastfeeding may influence breastfeeding decisions. The results are consistent with the idea that social support may influence breastfeeding duration and that some types of support are more influential than others. Furthermore, support persons should be educated about breastfeeding to prevent early weaning.  相似文献   

18.
19.
Agonistic support is generally considered a classical example of altruistic behaviour. It plays a critical role in the process of rank acquisition. This study investigates agonistic coalitions involving juvenile Japanese macaques (Macaca fuscata) living in a large captive group. Kinship was a good predictor of agonistic support received by juvenile macaques. Kinship also had a significant, though weaker, influence on agonistic support given by juvenile macaques. The latter was strongly influenced by the prospective rank of the individual against which the coalition was directed, i.e. by the rank relationship between the target of the coalition and the juvenile’s mother. Juvenile macaques intervened aggressively more against prospectively subordinate individuals than against prospectively dominant individuals. These results imply agonistic support is not necessarily altruistic, and support the hypothesis that primates may understand the rank relationship that exist among their group mates, i.e. that they are aware of third‐party social relationships. They also suggest that selective pressures associated with the process of rank acquisition may have favoured the evolution of higher cognitive abilities.  相似文献   

20.
Co-immobilization was applied to combine complementary enzyme reactions. Therefore, trypsin was co-immobilized together with both, lipase and alpha-amylase, onto the surface of non-woven polyester material. The progress of the immobilization reaction was directly monitored by investigating covalent fixation of the enzymes to the polyester flees using (1)H-MAS-NMR. Co-immobilization of the different types of enzymes to the polyester support showed retained enzymatic activity. However, a competition of binding to the support was observed. Increasing amounts of one type of enzyme reduced the degree of immobilization for the other type. In order to investigate the distribution of trypsin and alpha-amylase on the polyester support, the flees was treated with a mixture of rhodamine isothiocyanate labeled with anti-trypsin antibodies and fluorescein isothiocyanate labeled with anti-alpha-amylase antibodies. Using fluorescence microscopy, the co-immobilization was analyzed by selective excitation of both chromophores at 480 and 530 nm, respectively. In addition, fluorescence spectroscopy was applied by direct labeling of trypsin and lipase prior to co-immobilization to the polyester support. A special prism of plexiglass was constructed, which fit into a 10 x 10 mm fluorescence cuvette in that way that a diagonal plane was formed within the cuvette. The non-woven support was fixed in the cuvette and fluorescence spectra were obtained to characterize the amount of different enzymes linked to the support. Using FRET it was demonstrated that a uniform distribution of the various enzyme species was achieved, where the different enzyme activities are bound on the support in close neighborhood to one another.  相似文献   

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