scholarly journals Crucial Factors for Lyα Transmission in the Reionizing Intergalactic Medium: Infall Motion, H ii Bubble Size, and Self-shielded Systems

2021 ◽  
Vol 922 (2) ◽  
pp. 263
Author(s):  
Hyunbae Park ◽  
Intae Jung ◽  
Hyunmi Song ◽  
Pierre Ocvirk ◽  
Paul R. Shapiro ◽  
...  
Keyword(s):  
Sample Size ◽  
Bubble Size ◽  
Active Galactic Nucleus ◽  
Intergalactic Medium ◽  
Resonance Absorption ◽  
Neutral Fraction ◽  
Large Sample Size ◽  
Circular Velocity ◽  
The Galaxy ◽  
Average Transmission

Abstract Using the CoDa II simulation, we study the Lyα transmissivity of the intergalactic medium (IGM) during reionization. At z > 6, a typical galaxy without an active galactic nucleus fails to form a proximity zone around itself due to the overdensity of the surrounding IGM. The gravitational infall motion in the IGM makes the resonance absorption extend to the red side of Lyα, suppressing the transmission up to roughly the circular velocity of the galaxy. In some sight lines, an optically thin blob generated by a supernova in a neighboring galaxy results in a peak feature, which can be mistaken for a blue peak. Redward of the resonance absorption, the damping-wing opacity correlates with the global IGM neutral fraction and the UV magnitude of the source galaxy. Brighter galaxies tend to suffer lower opacity because they tend to reside in larger H ii regions, and the surrounding IGM transmits redder photons, which are less susceptible to attenuation, owing to stronger infall velocity. The H ii regions are highly nonspherical, causing both sight-line-to-sight-line and galaxy-to-galaxy variation in opacity. Also, self-shielded systems within H ii regions strongly attenuate the emission for certain sight lines. All these factors add to the transmissivity variation, requiring a large sample size to constrain the average transmission. The variation is largest for fainter galaxies at higher redshift. The 68% range of the transmissivity is similar to or greater than the median for galaxies with M UV ≥ −21 at z ≥ 7, implying that more than a hundred galaxies would be needed to measure the transmission to 10% accuracy.

scholarly journals Feasibility of Race by Sex Intersectionality Research on Suicidality in the Adolescent Brain Cognitive Development (ABCD) Study

Children ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 437
Author(s):  
Shervin Assari ◽  
Shanika Boyce ◽  
Mohsen Bazargan
Keyword(s):  
Cognitive Development ◽  
Sample Size ◽  
Child Behavior Checklist ◽  
Reliability And Validity ◽  
Self Report ◽  
Large Sample Size ◽  
Cross Sectional ◽  
Cronbach Alpha ◽  
Rich Data ◽  
Suicidal Ideas

Intersectional research on childhood suicidality requires studies with a reliable and valid measure of suicidality, as well as a large sample size that shows some variability of suicidality across sex by race intersectional groups. Objectives: We aimed to investigate the feasibility of intersectionality research on childhood suicidality in the Adolescent Brain Cognitive Development (ABCD) study. We specifically explored the reliability and validity of the measure, sample size, and variability of suicidality across sex by race intersectional groups. Methods: We used cross-sectional data (wave 1) from the ABCD study, which sampled 9013 non-Hispanic white (NHW) or non-Hispanic black (NHB) children between the ages of 9 and 10 between years 2016 and 2018. Four intersectional groups were built based on race and sex: NHW males (n = 3554), NHW females (n = 3158), NHB males (n = 1164), and NHB females (n = 1137). Outcome measure was the count of suicidality symptoms, reflecting all positive history and symptoms of suicidal ideas, plans, and attempts. To validate our measure, we tested the correlation between our suicidality measure and depression and Child Behavior Checklist (CBCL) sub-scores. Cronbach alpha was calculated for reliability across each intersectional group. We also compared groups for suicidality. Results: We observed some suicidality history in observed 3.2% (n = 101) of NHW females, 4.9% (n = 175) of NHW males, 5.4% (n = 61) of NHB females, and 5.8% (n = 68) of NHB males. Our measure’s reliability was acceptable in all race by sex groups (Cronbach alpha higher than .70+ in all intersectional groups). Our measure was valid in all intersectional groups, documented by a positive correlation with depression and CBCL sub-scores. We could successfully model suicidality across sex by race groups, using multivariable models. Conclusion: Given the high sample size, reliability, and validity of the suicidality measure, variability of suicidality, it is feasible to investigate correlates of suicidality across race by sex intersections in the ABCD study. We also found evidence of higher suicidality in NHB than NHW children in the ABCD study. The ABCD rich data in domains of social context, self-report, schools, parenting, psychopathology, personality, and brain imaging provides a unique opportunity to study intersectional differences in neural circuits associated with youth suicidality.

Numerical Assessment on Edgewise Compressive Strength of Heavy Sandwich Fiberboard

2015 ◽  
Vol 724 ◽  
pp. 74-78
Author(s):  
Guang Jun Hua ◽  
Wei Min Fei ◽  
Ze Shun Liao ◽  
Yong Xie
Keyword(s):  
Compressive Strength ◽  
Sample Size ◽  
Simulation Method ◽  
Large Sample Size ◽  
Heavy Duty ◽  
Material Consumption ◽  
Shape Processing ◽  
Reasonable Choice ◽  
Correct Understanding ◽  
Corrugated Fiberboard

The application status of heavy duty corrugated paperboard and honeycomb fiberboard were reviewed. In order to contrast the edgewise compressive strength of the two typical sandwich fiberboards, the finite element models of honeycomb fiberboard and AAB flute corrugated fiberboard with large sample size were established. By numerical simulation method, the effect of structure on the edgewise compressive strength were decoupled from the factor such as the materials, material consumption, sample size and shape, processing technology and environmental conditions etc. Under the same material, material consumption and sample size, bulking analysis based on numerical method was carried out. The results show that the edgewise compressive strength of both sides of the honeycomb fiberboard is about 50% higher than that of AAB flute corrugated fiberboard, and honeycomb fiberboard is similar to bi-isotropic material. The conclusions obtained are valuable to reasonable choice of the honeycomb fiberboard and heavy duty corrugated fiberboard and correct understanding the mechanical properties of the two sandwich fiberboard.

scholarly journals The Effectiveness Of High Levels Of Knowledge Regarding Hiv/Aids In Reducing Discriminatory Attitudes And Behaviour Towards Hiv-Infected People

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
M. Pirie ◽  
W. J. Coetsee
Keyword(s):  
Sample Size ◽  
Primary Objective ◽  
Large Sample Size ◽  
Infected People ◽  
Eta Squared ◽  
Secondary Objective ◽  
Level Of Knowledge ◽  
The Difference ◽  
F Statistics ◽  
Hiv Aids

The primary objective of this study was to assess whether there is a relationship between increasing levels of knowledge about HIV/AIDS and perceptions of discriminatory attitudes and behaviour towards people with HIV/AIDS. Employees (3662) from a large accounting firm were exposed to a survey and a response rate of 41% or 1532 was received. The secondary objective of the study was to determine whether there were any statistically significant differences in the mean difference of knowledge scores of groups created in terms of the different biographical variables. ANOVA’S (to determine the significance of differences between the means), t-tests (two groups only) and F-statistics were used for the analysis. Given the large sample size an F-test is not conclusive and the effect of the difference in sample size needs to be taken into account. For this reason it was also necessary to look at the Partial Eta Squared. Results indicate that respondents are generally knowledgeable about the prevention and transmission of HIV/AIDS and that respondents’ level of knowledge correlates negatively with discriminatory practices.

scholarly journals Detection of a Sub-Keplerian Water Maser Disk at the Active Galactic Nucleus of the Galaxy IC 1481

2009 ◽  
Vol 61 (5) ◽  
pp. 1143-1151 ◽  
Author(s):  
Koichi Mamyoda ◽  
Naomasa Nakai ◽  
Aya Yamauchi ◽  
Philip Diamond ◽  
Jean-Marc HurÉ
Keyword(s):  
Active Galactic Nucleus ◽  
The Galaxy ◽  
Water Maser

Validating the EUCS Model to Measure the Level of Satisfaction of Internet Users in Local Banks in Italy

2018 ◽  
Vol 30 (1) ◽  
pp. 66-81
Author(s):  
Rubens Pauluzzo ◽  
Enrico Fioravante Geretto
Keyword(s):  
Sample Size ◽  
User Satisfaction ◽  
Banking Sector ◽  
Internet Banking ◽  
Online Banking ◽  
Large Sample Size ◽  
Policy Makers ◽  
Internet Users ◽  
Level Of Satisfaction ◽  
Main Factors

In this study, the EUCS model has been used for measuring online banking user satisfaction in the local banking sector. The authors focused on Italian co-operative banks. The study involved the submission of a questionnaire to a sample of 600 retail consumers of small-sized co-operative banks. The model was tested with SEM techniques. The findings reinforce EUCS theory for internet banking satisfaction with large sample size, and provide evidence about the psychometric stability of the EUCS tool for measuring online banking user satisfaction in the local banking setting. The study will be useful to policy makers and banks to better understand why internet banking is not the favoured channel for service delivery in Italy and which are the main factors able to increase the acceptance of the online banking channel.

scholarly journals The importance of input data quality and quantity in climate field reconstructions – results from the assimilation of various tree-ring collections

2020 ◽  
Vol 16 (3) ◽  
pp. 1061-1074 ◽  
Author(s):  
Jörg Franke ◽  
Veronika Valler ◽  
Stefan Brönnimann ◽  
Raphael Neukom ◽  
Fernando Jaume-Santero
Keyword(s):  
Sample Size ◽  
Tree Ring ◽  
Input Data ◽  
Small Sample ◽  
Screening Methods ◽  
Temperature Sensitive ◽  
Data Sets ◽  
Large Sample Size ◽  
Spatial Coverage ◽  
Reconstruction Quality

Abstract. Differences between paleoclimatic reconstructions are caused by two factors: the method and the input data. While many studies compare methods, we will focus in this study on the consequences of the input data choice in a state-of-the-art Kalman-filter paleoclimate data assimilation approach. We evaluate reconstruction quality in the 20th century based on three collections of tree-ring records: (1) 54 of the best temperature-sensitive tree-ring chronologies chosen by experts; (2) 415 temperature-sensitive tree-ring records chosen less strictly by regional working groups and statistical screening; (3) 2287 tree-ring series that are not screened for climate sensitivity. The three data sets cover the range from small sample size, small spatial coverage and strict screening for temperature sensitivity to large sample size and spatial coverage but no screening. Additionally, we explore a combination of these data sets plus screening methods to improve the reconstruction quality. A large, unscreened collection generally leads to a poor reconstruction skill. A small expert selection of extratropical Northern Hemisphere records allows for a skillful high-latitude temperature reconstruction but cannot be expected to provide information for other regions and other variables. We achieve the best reconstruction skill across all variables and regions by combining all available input data but rejecting records with insignificant climatic information (p value of regression model >0.05) and removing duplicate records. It is important to use a tree-ring proxy system model that includes both major growth limitations, temperature and moisture.

scholarly journals No one accelerometer-based physical activity data collection protocol can fit all research questions

2019 ◽  
Author(s):  
Patrick Bergman ◽  
Maria Hagströmer
Keyword(s):  
Physical Activity ◽  
Sample Size ◽  
Large Sample Size ◽  
Intensity Level ◽  
Sample Sizes ◽  
Activity Data ◽  
Convenience Sample ◽  
Mean Values ◽  
Repeated Observations ◽  
Measurement Protocol

Abstract BACKGROUND Measuring physical activity and sedentary behavior accurately remains a challenge. When describing the uncertainty of mean values or when making group comparisons, minimising Standard Error of the Mean (SEM) is important. The sample size and the number of repeated observations within each subject influence the size of the SEM. In this study we have investigated how different combinations of sample sizes and repeated observations influence the magnitude of the SEM. METHODS A convenience sample were asked to wear an accelerometer for 28 consecutive days. Based on the within and between subject variances the SEM for the different combinations of sample sizes and number of monitored days was calculated. RESULTS Fifty subjects (67% women, mean±SD age 41±19 years) were included. The analyses showed, independent of which intensity level of physical activity or how measurement protocol was designed, that the largest reductions in SEM was seen as the sample size were increased. The same magnitude in reductions to SEM was not seen for increasing the number of repeated measurement days within each subject. CONCLUSION The most effective way of reducing the SEM is to have a large sample size rather than a long observation period within each individual. Even though the importance of reducing the SEM to increase the power of detecting differences between groups is well-known it is seldom considered when developing appropriate protocols for accelerometer based research. Therefore the results presented herein serves to highlight this fact and have the potential to stimulate debate and challenge current best practice recommendations of accelerometer based physical activity research.

scholarly journals DAMPAK BPNT TERHADAP KONSUMSI RUMAH TANGGA DAN POLA KONSUMSI RUMAH TANGGA PENERIMA BPNT, KECAMATAN MENGWI

2021 ◽  
pp. 839
Author(s):  
Luh Ade Yumita Handriani ◽  
Sudarsana Arka
Keyword(s):  
Path Analysis ◽  
Sample Size ◽  
Direct Effect ◽  
Indirect Effect ◽  
Household Consumption ◽  
Consumption Patterns ◽  
Consumption Pattern ◽  
Large Sample Size ◽  
Analysis Techniques ◽  
The Impact

This study aims to analyze the impact of the BPNT program on household consumption and consumption patterns of BPNT recipient households in Mengwi District, Badung Regency. This research was conducted in Mengwi District, Badung Regency using a questionnaire distributed to respondents with a large sample size of 96 KPM. This study uses path analysis techniques to analyze the direct effect and Sobel test to analyze the indirect effect. Based on path analysis, the results of the study concluded that the BPNT variable had a positive and significant effect on the consumption of BPNT recipient households in Mengwi District, Badung Regency. The BPNT variable has no effect on the consumption pattern of BPNT recipient households in Mengwi District, Badung Regency. The household consumption variable has a negative and significant effect on the consumption pattern of BPNT recipient households in Mengwi District, Badung Regency. The household consumption variable did mediate the effect of the BPNT Program on the consumption pattern of BPNT recipient households in Mengwi District, Badung Regency

scholarly journals The peril of adjusting for baseline when using change as a predictor

2019 ◽  
Author(s):  
Kimmo Sorjonen ◽  
Daniel Falkstedt ◽  
Bo Melin ◽  
Michael Ingre
Keyword(s):  
High Risk ◽  
Sample Size ◽  
Simulation Study ◽  
Strong Correlation ◽  
High Reliability ◽  
Large Sample Size ◽  
Present Simulation ◽  
Very High ◽  
Time Point

Some studies have analyzed the effect of a predictor measured at a later time point (X1), or of the X1-X0 difference, while adjusting for the predictor measured at baseline (X0), on some outcome Y of interest. The present simulation study shows that, if used to analyze the effect of change in X on Y, there is a high risk for this analysis to produce type 1-errors, especially with a strong correlation between true X and Y, when X0 and X1 are not measured with very high reliability, and with a large sample size. These problems are not encountered if analyzing the unadjusted effect of the X1-X0 difference on Y instead, and as this effect exhibits power on par with the adjusted effect it seems as the preferable method when using change between two measurement points as a predictor.

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