scholarly journals Host nutrition alters the variance in parasite transmission potential

2013 ◽  
Vol 9 (2) ◽  
pp. 20121145 ◽  
Author(s):  
Pedro F. Vale ◽  
Marc Choisy ◽  
Tom J. Little
Keyword(s):  
Risk Factors ◽  
Negative Binomial ◽  
Parasite Transmission ◽  
Transmission Potential ◽  
Population Average ◽  
Pasteuria Ramosa ◽  
Host Nutrition ◽  
Mean And Variance ◽  
The Mean ◽  
Crustacean Host

The environmental conditions experienced by hosts are known to affect their mean parasite transmission potential. How different conditions may affect the variance of transmission potential has received less attention, but is an important question for disease management, especially if specific ecological contexts are more likely to foster a few extremely infectious hosts. Using the obligate-killing bacterium Pasteuria ramosa and its crustacean host Daphnia magna , we analysed how host nutrition affected the variance of individual parasite loads, and, therefore, transmission potential. Under low food, individual parasite loads showed similar mean and variance, following a Poisson distribution. By contrast, among well-nourished hosts, parasite loads were right-skewed and overdispersed, following a negative binomial distribution. Abundant food may, therefore, yield individuals causing potentially more transmission than the population average. Measuring both the mean and variance of individual parasite loads in controlled experimental infections may offer a useful way of revealing risk factors for potential highly infectious hosts.

Estimating Rates of Recurrent Peritonitis for Patients on CAPO

1985 ◽  
Vol 5 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Edward F. Vonesh
Keyword(s):  
Risk Factors ◽  
Medical Devices ◽  
Negative Binomial ◽  
Survival Curve ◽  
Probability Model ◽  
Major Complication ◽  
Poisson Model ◽  
Negative Binomial Model ◽  
Binomial Model ◽  
The Mean

Recurrent peritonitis is a major complication of Continuous Ambulatory Peritoneal Dialysis (CAPD). As a therapy for patients with end stage renal disease, CAPD entails a continuous interaction between patient and various medical devices. The assumptions one makes regarding this interaction play an essential role when estimating the rate of recurrent peritonitis for a given patient population. Assuming that each patient has a constant rate of peritonitis, two models for evaluating the risk of recurrent peritonitis are considered. One model, the Poisson probability model, applies when the rate of peritonitis is the same from patient to patient. When this occurs, the frequency of peritoneal infections will be randomly distributed among patients (Corey, 1981). A second model, the negative binomial probability model, applies when the rate of peritonitis varies from one patient to another. In this event, the distribution of peritoneal infections will differ from patient to patient. The poisson model would be applicable when, for example, patients behave similarly with respect to their interactions with the medical devices and with potential risk factors. The negative binomial model, on the other hand, makes allowances for patient differences both in terms of their handling of routine exchanges and in their exposure to various risk factors. This paper provides methods for estimating the mean peritonitis rate under each model. In addition, “survival” curve estimates depicting the probability of remaining peritonitis free (i.e. “surviving”) over time are provided. It is shown, using data from a multi-center clinical trial, that the risk of peritonitis is best described in terms of survival curves rather than the mean peritonitis rate. For both models, the mean peritonitis rate was found to be 0.85 episodes per year. However, under the negative binomial model, the one-year survival rate, expressed as the percentage of patients remaining free of peritonitis, is 52% as compared with only 42% under the Poisson model. Moreover, the negative binomial model provided a significantly better fit to the observed frequency of peritonitis. These findings suggest that the negative binomial model provides a more realistic and accurate portrayal of the risk of peritonitis and that this risk is not nearly as high as would otherwise be indicated by a Poisson analysis.

scholarly journals VSS: Variance-stabilized signals for sequencing-based genomic signals

2020 ◽  
Author(s):  
Faezeh Bayat ◽  
Maxwell Libbrecht
Keyword(s):  
Negative Binomial ◽  
Empirical Relationship ◽  
Data Sets ◽  
Data Set ◽  
Variance Stabilization ◽  
Mean And Variance ◽  
The Mean ◽  
Genomic Signals ◽  
Mean Variance ◽  
Inverse Hyperbolic Sine

AbstractMotivationA sequencing-based genomic assay such as ChIP-seq outputs a real-valued signal for each position in the genome that measures the strength of activity at that position. Most genomic signals lack the property of variance stabilization. That is, a difference between 100 and 200 reads usually has a very different statistical importance from a difference between 1,100 and 1,200 reads. A statistical model such as a negative binomial distribution can account for this pattern, but learning these models is computationally challenging. Therefore, many applications—including imputation and segmentation and genome annotation (SAGA)—instead use Gaussian models and use a transformation such as log or inverse hyperbolic sine (asinh) to stabilize variance.ResultsWe show here that existing transformations do not fully stabilize variance in genomic data sets. To solve this issue, we propose VSS, a method that produces variance-stabilized signals for sequencingbased genomic signals. VSS learns the empirical relationship between the mean and variance of a given signal data set and produces transformed signals that normalize for this dependence. We show that VSS successfully stabilizes variance and that doing so improves downstream applications such as SAGA. VSS will eliminate the need for downstream methods to implement complex mean-variance relationship models, and will enable genomic signals to be easily understood by [email protected]://github.com/faezeh-bayat/Variance-stabilized-units-for-sequencing-based-genomic-signals.

scholarly journals Parasite transmission in a natural multihost–multiparasite community

2017 ◽  
Vol 372 (1719) ◽  
pp. 20160097 ◽  
Author(s):  
Stuart K. J. R. Auld ◽  
Catherine L. Searle ◽  
Meghan A. Duffy
Keyword(s):  
Disease Transmission ◽  
Transmission Rate ◽  
Ceriodaphnia Dubia ◽  
Reservoir Host ◽  
Parasite Transmission ◽  
Transmission Potential ◽  
Parasite Fitness ◽  
Dead End ◽  
Pasteuria Ramosa ◽  
Parasite Spillover

Understanding the transmission and dynamics of infectious diseases in natural communities requires understanding the extent to which the ecology, evolution and epidemiology of those diseases are shaped by alternative hosts. We performed laboratory experiments to test how parasite spillover affected traits associated with transmission in two co-occurring parasites: the bacterium Pasteuria ramosa and the fungus Metschnikowia bicuspidata . Both parasites were capable of transmission from the reservoir host ( Daphnia dentifera ) to the spillover host ( Ceriodaphnia dubia ), but this occurred at a much higher rate for the fungus than the bacterium. We quantified transmission potential by combining information on parasite transmission and growth rate, and used this to compare parasite fitness in the two host species. For both parasites, transmission potential was lower in the spillover host. For the bacterium, virulence was higher in the spillover host. Transmission back to the original host was high for both parasites, with spillover influencing transmission rate of the fungus but not the bacterium. Thus, while inferior, the spillover host is not a dead-end for either parasite. Overall, our results demonstrate that the presence of multiple hosts in a community can have important consequences for disease transmission, and host and parasite fitness. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.

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 Quantifying superspreading for COVID-19 using Poisson mixture distributions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cécile Kremer ◽  
Andrea Torneri ◽  
Sien Boesmans ◽  
Hanne Meuwissen ◽  
Selina Verdonschot ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Negative Binomial ◽  
Mixture Distributions ◽  
Infectious Individual ◽  
Transmission Process ◽  
Mean And Variance ◽  
The Mean ◽  
The One ◽  
Variance Estimates ◽  
Selection Of

AbstractThe number of secondary cases, i.e. the number of new infections generated by an infectious individual, is an important parameter for the control of infectious diseases. When individual variation in disease transmission is present, like for COVID-19, the distribution of the number of secondary cases is skewed and often modeled using a negative binomial distribution. However, this may not always be the best distribution to describe the underlying transmission process. We propose the use of three other offspring distributions to quantify heterogeneity in transmission, and we assess the possible bias in estimates of the mean and variance of this distribution when the data generating distribution is different from the one used for inference. We also analyze COVID-19 data from Hong Kong, India, and Rwanda, and quantify the proportion of cases responsible for 80% of transmission, $$p_{80\%}$$ p 80 % , while acknowledging the variation arising from the assumed offspring distribution. In a simulation study, we find that variance estimates may be biased when there is a substantial amount of heterogeneity, and that selection of the most accurate distribution from a set of distributions is important. In addition we find that the number of secondary cases for two of the three COVID-19 datasets is better described by a Poisson-lognormal distribution.

ANALYTICALLY CLOSED-FORM SOLUTIONS FOR THE DISTRIBUTION OF A NUMBER OF CUSTOMERS SERVED DURING A BUSY PERIOD FOR SPECIAL CASES OF THE GEO/G/1 QUEUE

2020 ◽  
pp. 1-30
Author(s):  
M. L. Chaudhry ◽  
Veena Goswami ◽  
Abdalla Mansur
Keyword(s):  
Busy Period ◽  
Negative Binomial ◽  
Closed Form Solutions ◽  
Early Arrival ◽  
Special Cases ◽  
Discrete Phase ◽  
Mean And Variance ◽  
The Mean ◽  
Limiting Case ◽  
Number Of Customers

Abstract This paper presents the distribution of the number of customers served during a busy period for special cases of the Geo/G/1 queue when initiated with m customers. We analyze the system under the assumptions of a late arrival system with delayed access and early arrival system policies. It is not easy to invert the functional equation for the number of customers served during a busy period except for the simple case Geo/Geo/1 queue, as stated by several researchers. Using the Lagrange inversion theorem, we give an elegant solution to this equation. We find the distribution of the number of customers served during a busy period for various service-time distributions such as geometric, deterministic, binomial, negative binomial, uniform, Delaporte, discrete phase-type and interrupted Bernoulli process. We compute the mean and variance of these distributions and also give numerical results. Due to the clarity of the expressions, the computations are very fast and robust. We also show that in the limiting case, the results tend to the analogous continuous-time counterparts.

Investigation of the Association Between Carotid Artery Intima-Media Thickness (IMT) and Cardiac Risk Factors in Patients with Systemic Lupus Erythematosus

2020 ◽  
Vol 16 (2) ◽  
pp. 125-133
Author(s):  
Zahra Rezaieyazdi ◽  
Sima Sedighi ◽  
Masoumeh Salari ◽  
Mohammadreza H. Fard ◽  
Mahmoud R. Azarpazhooh ◽  
...  
Keyword(s):  
Risk Factors ◽  
Insulin Resistance ◽  
Lupus Erythematosus ◽  
Serum Insulin ◽  
Venous Blood ◽  
Test Group ◽  
Control Groups ◽  
Significant Difference ◽  
The Mean ◽  
And Control

Background: The relationship between SLE and traditional risk factors for cardiovascular events was evaluated. Methods: The data regarding sixty patients with SLE and 30 healthy controls (age and sex matched) were gathered using SLEDAI forms. Venous blood (10mL) from all the participants was examined for hs-CRP, homocysteine, VCAM1, CBC, anti-DNA antibody, C3, C4, low-density lipoprotein (LDL), cholesterol, FBS and triglyceride. : The IMT of carotid arteries was determined bilaterally by ultrasound. Other measurements included insulin levels via Elisa (Linco/Millipore Corp) and the HOMA-IR index for insulin resistance. Results: The mean age (in years) in the test and control groups was 28.8±10.3 (18-52) and 33.8±9.13 (18-48), respectively. Results: The mean age (in years) in the test and control groups was 28.8±10.3 (18-52) and 33.8±9.13 (18-48), respectively. : The average IMT in the test group was directly related to serum levels of VCAM1 (p<0.001), homocysteine (p<0.001), cholesterol (p<0.009), LDL (p<0.001), TG (p<0.001), and FPG (p=0.004). The association between other risk factors, insulin resistance, carotid IMT and SLEDAI, was nonexistent. Mean insulin and insulin resistance levels in all the participants were 0.43±2.06 µU/mL and 0.09±0.44, respectively. There was no significant difference between the test and control groups regarding serum insulin and insulin resistance levels (p=0.42 and p=0.9, respectively). None of the risk factors, such as hsCRP, VCAM1, or homocysteine, were shown to be related to insulin resistance (p=0.6, p=0.6, p=0.09, respectively). Conclusion:: Our findings did not show an increase in the prevalence of atherosclerosis in patients with SLE. There was no association between IMT and insulin resistance. However, the former was associated with FPG, total cholesterol, LDL, TG, homocystein and VCAM1.

scholarly journals Weighted statistical binary patterns for facial feature representation

2021 ◽  
Author(s):  
Hung Phuoc Truong ◽  
Thanh Phuong Nguyen ◽  
Yong-Guk Kim
Keyword(s):  
Comprehensive Evaluation ◽  
Facial Feature ◽  
Input Image ◽  
Feature Representation ◽  
Illumination Variation ◽  
Straight Line ◽  
Mean And Variance ◽  
The Mean ◽  
Face Datasets ◽  
Degraded Images

AbstractWe present a novel framework for efficient and robust facial feature representation based upon Local Binary Pattern (LBP), called Weighted Statistical Binary Pattern, wherein the descriptors utilize the straight-line topology along with different directions. The input image is initially divided into mean and variance moments. A new variance moment, which contains distinctive facial features, is prepared by extracting root k-th. Then, when Sign and Magnitude components along four different directions using the mean moment are constructed, a weighting approach according to the new variance is applied to each component. Finally, the weighted histograms of Sign and Magnitude components are concatenated to build a novel histogram of Complementary LBP along with different directions. A comprehensive evaluation using six public face datasets suggests that the present framework outperforms the state-of-the-art methods and achieves 98.51% for ORL, 98.72% for YALE, 98.83% for Caltech, 99.52% for AR, 94.78% for FERET, and 99.07% for KDEF in terms of accuracy, respectively. The influence of color spaces and the issue of degraded images are also analyzed with our descriptors. Such a result with theoretical underpinning confirms that our descriptors are robust against noise, illumination variation, diverse facial expressions, and head poses.

scholarly journals Attitudes about Testicular Self-Examination among Polish Males

Biology ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 239
Author(s):  
Tomasz Milecki ◽  
Natalia Majchrzak ◽  
Adam Balcerek ◽  
Maciej Rembisz ◽  
Michał Kasperczak ◽  
...  
Keyword(s):  
Risk Factors ◽  
General Practitioner ◽  
Testicular Cancer ◽  
Family Member ◽  
Malignant Tumor ◽  
Epidemiological Data ◽  
Access To Information ◽  
The Mean ◽  
Original Survey ◽  
Self Examination

Introduction: Epidemiological data indicate an increased incidence of testicular cancer (TC), making it the most common malignant tumor in men from aged 15–45. Oncological and urological associations recommend that men with specific TC risk factors should regularly perform a testicular self-exam (TSE). The aim of the study was to discover the attitudes among Polish males regarding TSE and factors (environmental, social, educational) that affect intention to perform TSE. Methods: An original survey containing 21 questions was used to conduct a study among the Polish branch of VW (Volkswagen Poland) employees. Results: A total of 522 fully completed questionnaires were collected. The mean age of the surveyed respondents was 32 years. Information about TC and how to perform TSE was obtained by 34.4% (n = 185) of the men. It was shown that the following factors increase men’s intention to perform TSE: TC in their family member (p < 0.05; HR = 5.9; 95% Cl: 1.5–23.0), GP’s(General Practitioner) recommendations (p < 0.001; HR = 6.8; 95% Cl: 3.2–14.3), concern expressed by their partner (p < 0.001; HR = 3.3; 95% Cl: 2.1–5.3), and social campaigns (p < 0.001; HR = 2.6; 95% Cl: 1.5–4.6). Conclusions: Approximately half of young polish males do not perform TSE. Access to information on TC prevention is limited. Further action is needed to improve men’s awareness of TC and TSE.

scholarly journals Groups and Individuals: Optical Flow Patterns of Broiler Chicken Flocks Are Correlated with the Behavior of Individual Birds

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 568
Author(s):  
Sabine G. Gebhardt-Henrich ◽  
Ariane Stratmann ◽  
Marian Stamp Dawkins
Keyword(s):  
Optical Flow ◽  
Broiler Chicken ◽  
Average Length ◽  
Flow Patterns ◽  
Group Level ◽  
Positive Correlation ◽  
Water Test ◽  
Mean And Variance ◽  
The Mean

Group level measures of welfare flocks have been criticized on the grounds that they give only average measures and overlook the welfare of individual animals. However, we here show that the group-level optical flow patterns made by broiler flocks can be used to deliver information not just about the flock averages but also about the proportion of individuals in different movement categories. Mean optical flow provides information about the average movement of the whole flock while the variance, skew and kurtosis quantify the variation between individuals. We correlated flock optical flow patterns with the behavior and welfare of a sample of 16 birds per flock in two runway tests and a water (latency-to-lie) test. In the runway tests, there was a positive correlation between the average time taken to complete the runway and the skew and kurtosis of optical flow on day 28 of flock life (on average slow individuals came from flocks with a high skew and kurtosis). In the water test, there was a positive correlation between the average length of time the birds remained standing and the mean and variance of flock optical flow (on average, the most mobile individuals came from flocks with the highest mean). Patterns at the flock level thus contain valuable information about the activity of different proportions of the individuals within a flock.

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