scholarly journals Fitness patterns and phenotypic plasticity in a spatially heterogeneous environment

1996 ◽  
Vol 68 (3) ◽  
pp. 241-248 ◽  
Author(s):  
Lev A. Zhivotovsky ◽  
Marcus W. Feldman ◽  
Aviv Bergman
Keyword(s):  
Environmental Heterogeneity ◽  
Genetic System ◽  
Quadratic Functions ◽  
Heterogeneous Environment ◽  
Mean And Variance ◽  
Haploid Population ◽  
The Mean ◽  
The Difference ◽  
Analytical Expressions ◽  
Special Case

SummaryWe analyse patterns of the means and variances of genotypic fitnesses across different niches in a randomly mating haploid population. The population inhabits a spatially heterogeneous environment where it is subject to mutation and weak multilocus additive selection, with different selection coefficients in different niches. Approximate analytical expressions are derived for the stationary mean and variance of genotypic fitnesses among the niches in terms of environmental and genetic parameters. As a special case, we analyse an environment described by a variable t, distributed among the niches with mean t* and variance D*, and quadratic decrease in correlation between environments as a function of the difference in values of t. If the niches have the same qualities, the mean and variance of genotypic fitnesses evolve to be quadratic functions of t that achieve their maximum and minimum, respectively, at t*. With unequal niche qualities, these are non-polynomial functions that attain their extrema at different, usually intermediate values of t, although the coefficient of variation of the genotypic fitnesses still attains its minimum near t*. The functions involve the total mutation rate, the contribution of the loci to genotypic fitnesses, and the frequency and quality distributions of the niches. Thus, for this relatively simple model the norms of reaction may be calculated in terms of the detailed properties of the environmental heterogeneity, and the genetic system.

The Largest Missing Value in a Sample of Geometric Random Variables

2014 ◽  
Vol 23 (5) ◽  
pp. 670-685 ◽  
Author(s):  
MARGARET ARCHIBALD ◽  
ARNOLD KNOPFMACHER
Keyword(s):  
Random Variables ◽  
Random Variable ◽  
Missing Value ◽  
Asymptotic Expressions ◽  
Mean And Variance ◽  
The Mean ◽  
Special Case

We consider samples of n geometric random variables with parameter 0 < p < 1, and study the largest missing value, that is, the highest value of such a random variable, less than the maximum, that does not appear in the sample. Asymptotic expressions for the mean and variance for this quantity are presented. We also consider samples with the property that the largest missing value and the largest value which does appear differ by exactly one, and call this the LMV property. We find the probability that a sample of n variables has the LMV property, as well as the mean for the average largest value in samples with this property. The simpler special case of p = 1/2 has previously been studied, and verifying that the results of the present paper coincide with those previously found for p = 1/2 leads to some interesting identities.

Research on the Grading Theory of Thick and Thin Defects in the Electronic Testing for Raw Silk

2011 ◽  
Vol 175-176 ◽  
pp. 439-444 ◽  
Author(s):  
Jian Tao Niu ◽  
Qi Hu ◽  
Jian Mei Xu ◽  
Suo Zhuai Dong ◽  
Lun Bai
Keyword(s):  
Negative Binomial ◽  
Mean And Variance ◽  
The Mean ◽  
Spot Tests ◽  
The Difference ◽  
Grading Standards ◽  
The Right ◽  
Power Law Equation ◽  
The Relationship ◽  
Electronic Detector

Based on the sampling and grading theory of raw silk test, this paper studied the grading theory method of thick and thin defects of the raw silk in the electronic testing. By means of analyzing the data obtained from the raw silk electronic detector, the fact that the thick and thin defects of the raw silk appropriately take negative binomial distribution in the electronic testing has been confirmed. Under such circumstance, the distribution of the average of the sampling samples of the thick and thin defects was given, and fitting on the relationship between the mean and variance of the thick and thin defects were carried out by introducing Taylor’s power law equation, thus the right grading rate and probability of the difference between two spot tests about the thick and thin defects of the raw silk in the electronic testing was deduced. Moreover, the conclusion of the theoretical analysis was confirmed by simulation tests. The results might provide a basis for establishing the grading standards of the thick and thin defects in the electronic testing for raw silk.

scholarly journals Jack knifing for semivariogram validation

Bragantia ◽  
2010 ◽  
Vol 69 (suppl) ◽  
pp. 97-105 ◽  
Author(s):  
Sidney Rosa Vieira ◽  
José Ruy Porto de Carvalho ◽  
Antonio Paz González
Keyword(s):  
Correlation Coefficient ◽  
Square Root ◽  
Trend Surface ◽  
Strong Trend ◽  
Function Fitting ◽  
Mean And Variance ◽  
The Mean ◽  
The Difference ◽  
Distinct Field ◽  
The Ideal

The semivariogram function fitting is the most important aspect of geostatistics and because of this the model chosen must be validated. Jack knifing may be one the most efficient ways for this validation purpose. The objective of this study was to show the use of the jack knifing technique to validate geostatistical hypothesis and semivariogram models. For that purpose, topographical heights data obtained from six distinct field scales and sampling densities were analyzed. Because the topographical data showed very strong trend for all fields as it was verified by the absence of a sill in the experimental semivariograms, the trend was removed with a trend surface fitted by minimum square deviation. Semivariogram models were fitted with different techniques and the results of the jack knifing with them were compared. The jack knifing parameters analyzed were the intercept, slope and correlation coefficient between measured and estimated values, and the mean and variance of the errors calculated by the difference between measured and estimated values, divided by the square root of the estimation variances. The ideal numbers of neighbors used in each estimation was also studied using the jack knifing procedure. The jack knifing results were useful in the judgment of the adequate models fitted independent of the scale and sampling densities. It was concluded that the manual fitted semivariogram models produced better jack knifing parameters because the user has the freedom to choose a better fit in distinct regions of the semivariogram.

scholarly journals Reliability Analysis of Intersection Sight Distance at Roundabouts

2020 ◽  
Vol 5 (8) ◽  
pp. 67 ◽  
Author(s):  
Said M. Easa ◽  
Yang Ma ◽  
Shixu Liu ◽  
Yanqun Yang ◽  
Shriniwas Arkatkar
Keyword(s):  
Sight Distance ◽  
Reliability Method ◽  
First Order Second Moment ◽  
Design Values ◽  
Mean And Variance ◽  
Coefficients Of Variations ◽  
The Mean ◽  
Lateral Clearance ◽  
Second Moment Method ◽  
Special Case

This paper presents a reliability-based method for the design of intersection sight distance (ISD) at traffic roundabouts using the linear and nonlinear deceleration profiles of the entry vehicles. The reliability method is based on the first-order second moment method which is simple and relatively accurate compared with advanced methods. The nonlinear deceleration profile includes a shape parameter that produces the linear profile as a special case. Deterministic and reliability-based formulas for the required ISD for an approaching vehicle are developed for the entry vehicle on the left and the vehicle on the circulating roadway. Then, the design values of the ISD legs, applicable to any type of roundabout, are presented for different probabilities of non-compliance (Pnc) and different coefficients of variations. For the special case of single-lane symmetrical roundabouts, which have a well-defined geometry, the lateral clearance needs are established. The sensitivity analysis shows that ISD is very sensitive to both the mean and variance of the critical headway. The results show that the deterministic method results in ISD values that correspond to a very small Pnc, indicating that the method is very conservative. The proposed method, which provides flexibility in selecting ISD for any given Pnc, should be of interest to highway designers and practitioners to promote roundabout safety.

scholarly journals Micrometeorological conditions of the soloteca of Embrapa Solos -Rio de Janeiro, Brazil

2021 ◽  
Vol 1 (2) ◽  
pp. 50-57
Author(s):  
Evaldo de Paiva Lima ◽  
Rosandro Boligon Minuzzi ◽  
Yuri de Almeida Lyra Corrêa ◽  
Camila Sanches De Oliveira
Keyword(s):  
Air Temperature ◽  
Soil Samples ◽  
The Other ◽  
Outdoor Environments ◽  
Mean And Variance ◽  
The Mean ◽  
The Difference ◽  
Indoor And Outdoor Environments ◽  
Micrometeorological Conditions ◽  
Indoor And Outdoor

Soloteca is the term used in Brazil to refer to the place where reference soil samples are stored. The Soloteca of Embrapa Solos-RJ, for example, stores soil samples from different regions of Brazil, and these samples need to be stored in conditions that preserve their intrinsic characteristics. In this context, the objective of this work was to determine the air temperature and relative humidity conditions in the Soloteca of Embrapa Solos-RJ. The data were collected by three Thermo hygrometers, installed inside and outside the place where the samples are stored, in the period from December 1, 2016, to March 31, 2017, corresponding to summer 2016/17. The difference between the mean and variance of the data for each environment/height was evaluated at the 5% level, respectively, by the  t-Student and Snedecor's F tests. The other statistical analyses were presented by boxplots. It was observed that the air temperature, on average, did not differ between the indoor and outdoor environments at a height of 1.6 meters, but there was a difference with the sensor installed near the surface (0.5 meters). On the other hand, the dispersion of the data attested by the variance and the coefficient of variation in the external environment was greater than those recorded internally.

scholarly journals Statistical Model of Correlation Difference and Related-Key Linear Cryptanalysis

2021 ◽  
pp. 124-137
Author(s):  
Kaisa Nyberg
Keyword(s):  
Boolean Functions ◽  
Multinomial Distribution ◽  
Linear Cryptanalysis ◽  
Multivariate Normal ◽  
Linear Approximations ◽  
Multidimensional Linear Approximation ◽  
Multivariate Normal Approximation ◽  
Mean And Variance ◽  
The Mean ◽  
The Difference

The goal of this work is to propose a related-key model for linear cryptanalysis. We start by giving the mean and variance of the difference of sampled correlations of two Boolean functions when using the same sample of inputs to compute both correlations. This result is further extended to determine the mean and variance of the difference of correlations of a pair of Boolean functions taken over a random data sample of fixed size and over a random pair of Boolean functions. We use the properties of the multinomial distribution to achieve these results without independence assumptions. Using multivariate normal approximation of the multinomial distribution we obtain that the distribution of the difference of related-key correlations is approximately normal. This result is then applied to existing related-key cryptanalyses. We obtain more accurate right-key and wrong-key distributions and remove artificial assumptions about independence of sampled correlations. We extend this study to using multiple linear approximations and propose a Χ2-type statistic, which is proven to be Χ2 distributed if the linear approximations are independent. We further examine this statistic for multidimensional linear approximation and discuss why removing the assumption about independence of linear approximations does not work in the related-key setting the same way as in the single-key setting.

Direct method for determining constant corrections to geophysical survey lines for reducing mis‐ties

Geophysics ◽  
1990 ◽  
Vol 55 (7) ◽  
pp. 885-896 ◽  
Author(s):  
W. L. Bandy ◽  
A. F. Gangi ◽  
F. D. Morgan
Keyword(s):  
Functional Form ◽  
Least Squares Method ◽  
Direct Method ◽  
Polynomial Method ◽  
Test Cases ◽  
Geophysical Surveys ◽  
The Mean ◽  
The Difference ◽  
Original Survey ◽  
Special Case

A least‐squares method of minimizing mis‐ties in geophysical surveys yields a simple, direct method for determining constant corrections along each crossing survey line. This “direct method” is a special case of the more general, orthogonal polynomial method of Foster et al. (1970). The constant corrections are determined directly from the observed data, eliminating the need to iterate or invert a matrix to determine the corrections as in previously published, constant‐correction algorithms. The magnitude of the constant correction to the field values along a particular line equals the difference between the mean mis‐tie value for that line and one‐half the mean mis‐tie for the entire survey. The method minimizes both the mis‐ties and the distortion of the original survey; namely, the mean squared mis‐tie for the entire survey and the mean squared corrections are both minimized. Application of the direct method to test cases in which known errors are added to known “true” field values along survey lines in an (x, y) plane indicates that (1) the mis‐ties are completely eliminated if their functional form contains only terms which are functions of either x or y, regardless of the functional form of the errors themselves, (2) the method preserves both the relative field values along the survey lines and the original mean error of the survey, (3) the corrections are independent of the true field, (4) errors common to both intersecting lines will remain in the final map, and (5) the resulting corrected field is not necessarily a more accurate representation of the “true” field even when the mis‐ties are completely eliminated.

The Effect of Vocabulary Intervention on Text Comprehension: Who Benefits?

2019 ◽  
Vol 50 (4) ◽  
pp. 562-578 ◽  
Author(s):  
Dawna Duff
Keyword(s):  
Middle School ◽  
Reading Comprehension ◽  
Text Comprehension ◽  
Classroom Instruction ◽  
Vocabulary Instruction ◽  
Clinical Intervention ◽  
Vocabulary Knowledge ◽  
Vocabulary Intervention ◽  
The Mean ◽  
The Difference

Purpose Vocabulary intervention can improve comprehension of texts containing taught words, but it is unclear if all middle school readers get this benefit. This study tests 2 hypotheses about variables that predict response to vocabulary treatment on text comprehension: gains in vocabulary knowledge due to treatment and pretreatment reading comprehension scores. Method Students in Grade 6 ( N = 23) completed a 5-session intervention based on robust vocabulary instruction (RVI). Knowledge of the semantics of taught words was measured pre- and posttreatment. Participants then read 2 matched texts, 1 containing taught words (treated) and 1 not (untreated). Treated texts and taught word lists were counterbalanced across participants. The difference between text comprehension scores in treated and untreated conditions was taken as a measure of the effect of RVI on text comprehension. Results RVI resulted in significant gains in knowledge of taught words ( d RM = 2.26) and text comprehension ( d RM = 0.31). The extent of gains in vocabulary knowledge after vocabulary treatment did not predict the effect of RVI on comprehension of texts. However, untreated reading comprehension scores moderated the effect of the vocabulary treatment on text comprehension: Lower reading comprehension was associated with greater gains in text comprehension. Readers with comprehension scores below the mean experienced large gains in comprehension, but those with average/above average reading comprehension scores did not. Conclusion Vocabulary instruction had a larger effect on text comprehension for readers in Grade 6 who had lower untreated reading comprehension scores. In contrast, the amount that children learned about taught vocabulary did not predict the effect of vocabulary instruction on text comprehension. This has implications for the identification of 6th-grade students who would benefit from classroom instruction or clinical intervention targeting vocabulary knowledge.

Efficacy and Safety of Oral Ivermectin and Topical Permethrin in the Treatment of Scabies

2020 ◽  
Vol 33 (1) ◽  
pp. 41-47
Author(s):  
Mohsena Akhter ◽  
Ishrat Bhuiyan ◽  
Zulfiqer Hossain Khan ◽  
Mahfuza Akhter ◽  
Gulam Kazem Ali Ahmad ◽  
...  
Keyword(s):  
Skin Diseases ◽  
Close Contact ◽  
Randomized Study ◽  
Sarcoptes Scabiei ◽  
Efficacy And Safety ◽  
Common Skin ◽  
Group A ◽  
The Mean ◽  
The Difference ◽  
Group B

Background: Scabies is one of the most common skin diseases in our country. It is caused by the mite Sarcoptes scabiei var hominis, which is an ecto-parasite infesting the epidermis. Scabies is highly contagious. Prevalence is high in congested or densely populated areas. Individuals with close contact with an affected person should be treated with scabicidal which is available in both oral and topical formulations. The only oral but highly effective scabicidal known to date is Ivermectin. Amongst topical preparations, Permethrin 5 % cream is the treatment of choice. Objective: To evaluate the efficacy & safety of oral Ivermectin compared to topical Permethrin in the treatment of scabies. Methodology: This prospective, non-randomized study was conducted at the out-patient department of Dermatology and Venereology of Shaheed Suhrawardy Medical College & Hospital over a period of 6 months, from August 2016 to January 2017. The study population consisted of one hundred patients having scabies, enrolled according to inclusion criteria. They were divided into two groups. group A was subjected to oral Ivermectin and the group B to Permethrin 5% cream. Patients were followed up on day 7 and 14 for assessment of efficacy and safety. Result: The mean scoring with SD in group A (Ivermectin) and group B (Permethrin) were 8.26 ± 2.22 and 7.59 ± 2.01 respectively at the time of observation. The difference between the mean score of the two group is not significant (p=0.117) the mean scoring with SD in group A and group B were 4.54 ± 2.05 and 1.64 ± 1.84 respectively at 7thdays. The difference between the mean score of the two group is significant (p<0.001). The mean scoring with SD in group A and group B were 2.68± 2.35 and .36± 1.10 respectively at 14th day difference between the mean score of the group is significant (p<0.001). Conclusion: Topical application of permethrin 5% cream is more effective and safer than oral Ivermectin in the treatment of scabies. TAJ 2020; 33(1): 41-47

EFFECTS OF SYNTHETIC LH/FSH-RELEASING HORMONE (LRH) ON PLASMA LH AND FSH IN AMENORRHOEIC WOMEN

1974 ◽  
Vol 75 (4) ◽  
pp. 647-652 ◽  
Author(s):  
G. Rannevik ◽  
J. Thorell
Keyword(s):  
Urinary Excretion ◽  
Initial Response ◽  
Releasing Hormone ◽  
The Mean ◽  
The Difference ◽  
Serial Measurements

ABSTRACT Eight amenorrhoeic women were given 100 μg synthetic LRH (Hoechst) iv and im, respectively, at an interval of 2 weeks. Four of the women received the iv injection first and four the im injection. The urinary excretion of oestrogens and pregnanediol was low and unaltered throughout the test weeks. The effects of LRH were compared by serial measurements of the plasma LH and FSH during 8 h. The initial response of LH for up to 25 min and that of FSH for up to 60 min were equal whether LRH was given iv or im. The difference appeared later. Four hours after the injection the mean increase of LH to iv injection was 0.5 ng/ml (N. S.), while that to im injection was 1.9 ng/ml (P < 0.01). The corresponding values for FSH were 1.3 (P < 0.05) and 3.2 (P < 0.001). The effect of LRH administration im was thus found to be larger and more prolonged.

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