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1.
Contextual shifts were observed for sweetness of a fruit beverage and for estimated tactile roughness of sandpapers. Midrange stimuli were judged to be less intense in the context of stronger items and more intense in the context of weaker items, a contrast effect. The use of a reference standard decreased the size of the contrast shift for the labeled magnitude scale but not for magnitude estimation.  相似文献   

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1. Tissue sections eight microns thick were exposed to various experimental conditions used in histochemistry, and the effect upon the activities of esterase, the phosphatases, leucine aminopeptidase, β-glucuronidase, and arylsulfatase was determined colorimetrically. 2. Significant differences were found in the amounts of the lyo and desmo fractions of these enzymes. The desmo components were found to be for esterase, alkaline phosphatase, leucine aminopeptidase, acid phosphatase, β-glucuronidase, and arylsulfatase, ⅓, 2/3, 2/3, ½, ⅛, and ⅛ of the total enzymatic activity respectively. 3. Variations in the time and in the temperature at which diffusion was studied and of the pH and salt concentration of the solution into which the sections were placed, resulted in differences in the amount of enzymatic activity which remained in the tissue section. Some enzyme loss by diffusion was noted even after fixation of the tissue section. 4. The significance of the findings with respect to some of the concepts of localization of enzymes in tissue sections was discussed.  相似文献   

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Recent studies comparing magnitude estimation to other scaling methods have been criticized for failure to submit the data to logarithmic transformation before statistical analysis, a procedure which can improve the ability of magnitude estimation scaling to differentiate among products. Data from one of these studies was available for re-analysis, which was conducted both with and without logarithmic transformation of magnitude estimation, category scales and line scales. The ability of magnitude estimation to differentiate among products was improved by log transformation, while the other methods were not. Improvements were associated in pan with reductions in positive skew and improved approximation of the normal distribution. In spite of this improvement, magnitude estimation remained slightly inferior to the other methods especially in the hands of an untrained consumer sample.  相似文献   

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Three methods of standardizing magnitude estimation data, external calibration, modulus normalization, and equalization were examined using a sensory evaluation data set arising from an incomplete block experiment testing five gels of varying firmness. Both the original data and a logarithmic transformation of the data were analyzed. Instrumental data were also collected. When untransformed data were analyzed the method of standardization profoundly affected tests of significance, coefficients of variation (%CV), and estimation of the power function relating the sensory data to the concentration of the underlying gel. The logarithmically transformed data lead to results independent of the standardizing technique and with higher F-ratios, lower %CV's and normally distributed errors.  相似文献   

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The use of linear time series, as a psychophysical method ofassessing self-adaptation and carryover effects in olfactoryintensity judgments, is illustrated for eugenol and acetophenone.Data from series of 60 successive magnitude estimation judgmentsby 11 subjects show consistent within-subject and between-subjectdifferences. The two substances used do not show the same self-adaptationpatterns.  相似文献   

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Judges rated the intensity of NaCl solutions using magnitude estimation and the labeled magnitude scale. They performed under four response conditions that varied in reliance on memory: (1) verbal response, (2) written response with no retasting and the response sheet removed, (3) written response with a single response sheet which allowed past scores to be reviewed and amended but with no retasting, (4) the same as '3' but with retasting. Discrimination errors tended to decrease from conditions '1' through '4' yet the major and significant effect was allowing judges to retaste stimuli. The effects of how forgetting lowered discrimination were discussed in the context of experimental design and the absolute versus relative cognitive models of scaling.  相似文献   

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In this paper we present a method for estimating population divergence times by maximum likelihood in models without mutation. The maximum-likelihood estimator is compared to a commonly applied estimator based on Wright's FST statistic. Simulations suggest that the maximum-likelihood estimator is less biased and has a lower variance than the FST-based estimator. The maximum-likelihood estimator provides a statistical framework for the analysis of population history given genetic data. We demonstrate how maximum-likelihood estimates of the branching pattern of divergence of multiple populations may be obtained. We also describe how the method may be applied to test hypotheses such as whether populations have maintained equal population sizes. We illustrate the method by applying it to two previously published sets of human restriction fragment length polymorphism (RFLP) data.  相似文献   

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Differential inductive capacities among liver tissues of several animals were examined by anticipating the correlation between the capacity and the completness of perisinusoidal basement membrane.
The reacting tissue was competent ectoderm of gastrula of Triturus pyrrhogaster , and the inductive effects of livers on the ectoderm were tested by explantation method. The inductive effect of livers being devoid of the membrane (chick and guinea pig) was neural and the tissues having the dense well-developed membrane (reptiles) produced an assembly of neural and meso-dermal tissues, such as notochord and somite or muscle. The livers with the membrane being of intermediate grade of development ( calf, Triturus and mouse) induce mesodermal tissues, but not frequently, together with neural tissue or alone. The liver tissue was more active in mesodermal induction in proportion to the completeness of the perisinusoidal basement membrane.
On the basis of these data the difference in inductive capacity among liver tissues from different kinds of animals were discussed.  相似文献   

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目的探讨吸烟患慢性阻塞性肺疾病(chronic obstructive pul monary disease,COPD)者与吸烟不患COPD者肺组织中白介素-18(interleukin-18,IL-18)表达水平的差异。方法不吸烟不患COPD(Control组)、吸烟不患COPD(Smoker组)和吸烟患COPD(COPD组)患者各10例,性别、年龄相匹配,均为因肺部占位病变行肺叶切除术患者,取材尽量远离病变组织,采用HE染色观察各组肺组织形态学变化,用免疫组织化学染色方法,检测IL-18在肺组织的表达。结果1.HE染色显示正常对照组与吸烟不患COPD组无明显炎症变化;COPD组肺组织有明显的肺泡结构破坏和炎症细胞浸润,炎性细胞较Control组和Smoker组明显增加。2.免疫组化染色图像分析显示,Control组IL-18的平均光密度值为0.472±0.134,Smoker组为0.622±0.090,COPD组为0.897±0.193,COPD组与Control组和Smoker组之间有显著统计学差异(n均为10,P0.01),并且Smoker组和Control组之间也存在统计学差异(P0.05)。将30例受试者作为整体分析,肺组织中IL-18表达(平均光密度值表示)分别与肺功能指标FEV1/FVC、FEV1(%pred)之间存在显著的负的直线相关关系(n=30,r=-0.778,P0.01和n=30,r=-0.520,P0.01)。结论吸烟患COPD者肺组织中IL-18的表达较不患COPD者明显增加,IL-18在肺部的表达量与气流受限程度具有显著相关性,提示IL-18在吸烟致COPD的发病机制中可能起重要作用。  相似文献   

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1. Detmer''s solution and a modified Knop''s solution are unfavorable culture media for the growth of Spirodela polyrhiza. 2. When the modified Knop''s solution was diluted to 10 times its volume, Spirodela polyrhiza and Lemna valdiviana grew and reproduced for periods of 26 months and 21 months, respectively. 3. Growth in the dilute Knop''s solution, which alone can support the growth of Spirodela indefinitely, was considerably stimulated over a period of 23 days by adding to every liter the water-soluble material of 0.4 gm. autolyzed yeast, or the material of 2.5 gm. peat soluble in a 1 per cent solution of NaHCO3. 4. The nature of the stimulus or of the protection afforded by the organic material is as yet unknown. 5. The necessity of organic accessory foods (auximones) in the nutrition of green plants cannot be accepted as an established fact.  相似文献   

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The formation from hemoglobin of split products not precipitable by trichloracetic acid is taken as a measure of tryptic activity. The split products are estimated colorimetrically. Many measurements of tryptic activity can be made in a short time and different samples of hemoglobin yield the same results.  相似文献   

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Many long‐lived plant and animal species have nondiscrete overlapping generations. Although numerous models have been developed to predict the effective sizes (Ne) of populations with overlapping generations, they are extremely difficult to apply to natural populations because of the large array of unknown and elusive life‐table parameters involved. Unfortunately, little work has been done to estimate the Ne of populations with overlapping generations from marker data, in sharp contrast to the situation of populations with discrete generations for which quite a few estimators are available. In this study, we propose an estimator (EPA, estimator by parentage assignments) of the current Ne of populations with overlapping generations, using the sex, age, and multilocus genotype information of a single sample of individuals taken at random from the population. Simulations show that EPA provides unbiased and accurate estimates of Ne under realistic sampling and genotyping effort. Additionally, it yields estimates of other interesting parameters such as generation interval, the variances and covariances of lifetime family size, effective number of breeders of each age class, and life‐table variables. Data from wild populations of baboons and hihi (stitchbird) were analyzed by EPA to demonstrate the use of the estimator in practical sampling and genotyping situations.  相似文献   

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《Chronobiology international》2013,30(6):1189-1205
There is a strong association between metabolic syndrome (MS) and increased risk of end-organ damage, cardiovascular disease, stroke, and cardiovascular mortality. Moreover, non-dipping (<?10% decline in the asleep relative to the awake blood pressure [BP] mean) and elevated ambulatory pulse pressure (PP), among other factors related to the circadian BP pattern, have also been associated with increased cardiovascular morbidity and mortality. This cross-sectional study investigated the circadian BP pattern in 2,045 non-diabetic untreated patients with uncomplicated essential hypertension (941 men/1,099 women), 48.7?±?11.9 yrs of age, classified by the presence or absence of MS. BP was measured by ambulatory monitoring for 48 consecutive hours to substantiate reproducibility of the dipping pattern. Physical activity was simultaneously monitored every min by wrist actigraphy to accurately calculate mean BP when awake and asleep for each subject. MS was present in 40.7% of the patients. Patients with MS were characterized by a significantly higher 24?h mean of systolic BP and a lower diastolic BP compared to patients without MS. Accordingly, ambulatory PP was significantly elevated the entire 24?h in MS patients. The prevalence of an altered non-dipper BP profile was significantly higher in MS patients (48.4 vs. 36.1% in patients without MS, p?<?0.001). MS patients were characterized, among other risk factors, by significantly higher uric acid, fibrinogen, leukocyte count, hemoglobin and globular sedimentation velocity, plus lower estimated glomerular filtration rate. Apart from corroborating the significant increased prevalence of a blunted nocturnal BP decline in MS, this study documents ambulatory PP is higher in MS, without differences between groups in mean arterial pressure. This elevated PP might reflect increased arterial stiffness in MS. MS patients were also characterized by elevated values of relevant markers of cardiovascular risk, including fibrinogen and globular sedimentation velocity. These collective findings indicate that MS should be included among the clinical situations in which ambulatory BP monitoring is recommended. (Author correspondence: )  相似文献   

20.
The field cricket Teleogryllus oceanicus has been introduced to Hawaii, where it is parasitized by an acoustically orienting parasitoid fly, Ormia ochracea. Previous work showed that call parameters from parasitized populations differ from those in unparasitized populations in a direction expected if selection by flies is occurring. Here we examined songs of males collected in the field and compare calling song characters of crickets later found to harbor parasitoid larvae with those of males free of parasitoids. The two groups differ significantly in several song characteristics, particularly the trill-like long chirp given at the beginning of each song. Males with longer long chirps containing shorter interpulse intervals are more likely to be parasitized, suggesting that the flies find such males more attractive. Depending on the traits females prefer, sexual selection may oppose natural selection in altering T. oceanicus song in parasitized populations.  相似文献   

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