110 research outputs found
Adjusting for Publication Bias in JASP and R: Selection Models, PET-PEESE, and Robust Bayesian Meta-Analysis
Meta-analyses are essential for cumulative science, but their validity can be compromised by publication bias. In order to mitigate the impact of publication bias, one may apply publication bias adjustment techniques such as PET-PEESE and selection models. Implemented in JASP & R, these methods allow researchers without programming experience to conduct state-of-the-art publication bias adjusted meta-analysis. In this tutorial, we demonstrate how to conduct a publication bias adjusted meta-analysis in JASP & R and interpret the results. First, we explain two frequentist bias correction methods: PET-PEESE and selection models. Second, we introduce robust Bayesian meta-analysis (RoBMA), a Bayesian approach that simultaneously considers both PET-PEESE and selection models. We illustrate the methodology on an example data set, provide instructional video (https://bit.ly/pubbias), R-markdown script (https://osf.io/uhaew/), and discuss the interpretation of the results. Finally, we include concrete guidance on reporting the meta-analytic results in an academic article
Giant valley-selective Stark and Bloch-Siegert shifts of exciton resonances in WSe and MoS monolayers
In this letter we demonstrate that the valley degeneracy of exciton states in
monolayers of WSe and MoS can be lifted by the interaction with strong
circularly-polarized infrared pulses with durations of only few periods of the
electric field whose photon energy is much lower than the energy of the
excitonic transition. The observed valley-sensitive blue shifts of excitonic
absorption lines are consequences of optical Stark and Bloch-Siegert shifts
acting exclusively on the opposite valleys of the monolayer. We measured the
transient valley-selective changes of sample reflectivity for 1sA as well as
for 1sB exciton transitions corresponding to the two most intensive resonances
in the studied materials. For the studied phenomena we developed a theoretical
description based on semiconductor Bloch equations, which goes beyond the
simple two-level model used in previous investigations. The theoretical
approach takes into account Coulomb many-body effects in the monolayer and
provides a unified description of both types of shifts. The detected
room-temperature excitonic energy shifts of up to 30\,meV pave the way for
practical applications of these effects.Comment: 6 pages, 3 figures, the manuscript is related to the "Semiconductor
Bloch equation analysis of optical Stark and Bloch-Siegert shifts in
monolayers WSe and MoS" manuscrip
Semiconductor Bloch equation analysis of optical Stark and Bloch-Siegert shifts in monolayers WSe and MoS
We report on the theoretical and experimental investigation of
valley-selective optical Stark and Bloch-Siegert shifts of exciton resonances
in monolayers WSe and MoS induced by strong circularly polarized
nonresonant optical fields. We predict and observe transient shifts of both 1sA
and 1sB exciton transitions in the linear interaction regime. The theoretical
description is based on semiconductor Bloch equations. The solutions of the
equations are obtained with a modified perturbation technique, which takes into
account many-body Coulomb interaction effects. These solutions allow to explain
the polarization dependence of the shifts and calculate their values
analytically. We found experimentally the limits of the applicability of the
theoretical description by observing the transient exciton spectra change due
to many-body effects at high field amplitudes of the driving wave.Comment: 20 pages, 9 figures, this manuscript is related to the "Giant
valley-selective Stark and Bloch-Siegert shifts of exciton resonances in
WSe and MoS monolayers" manuscrip
The lepton pair production in heavy ion collisions in perturbation theory
We derive the first terms in the amplitude of lepton pair production in the
Coulomb fields of two relativistic heavy ions. Using the Sudakov technique,
which very simplify the calculations in momentum space for the processes at
high energies, we get the compact analytical expressions for differential cross
section of the process under consideration in the lowest order in fine
structure constant (Born approximation) valid for any momentum transfer and in
a wide kinematics region for produced particles. Exploiting the same technique
we consider the next terms of perturbation series (up to fourth order in fine
structure constant) and investigate their energy dependence and limiting cases.
It has been shown that taking in account all relevant terms in corresponding
order one obtains the expressions which are gauge invariant and finite. We
estimate the contribution of the Coulomb corrections to the total cross section
and discuss the cancellations of the different terms which holds in the total
cross section.Comment: LaTeX2e, 18 pages, 4 eps figure
Failure of noninvasive prediction of pulmonary hypertension in patients with idiopathic pulmonary fibrosis
Background. Pulmonary hypertension (PH) in patients with advanced idiopathic pulmonary fibrosis (IPF) is a complication connected with unfavorable prognosis. Great efforts have been made in attempting to establish a reliable non-invasive method which would enable detection of this complication. In this context a formula using pulmonary function parameters was published with outstanding results. Methods. We tested the formula in 27 IPF patients who underwent a lung function examination, cardiac ultrasonography and catheterisation on the same day. Results. Pulmonary hypertension was detected by catheterisation in 17 patients (63%). In our group, contrary to the published data, the aforementioned formula was neither useful for detecting patients with a high probability of PH nor as a means of calculating the mean pulmonary artery pressure in individual patients (p=0.502 and p=0.833, respectively). Ultrasound examination reached borderline correlation with the values measured by catheterisation when we compare patients with relevant results (r=0.531, p=0.051). However, the examination gave no usable results in 13 patients (48%). Conclusion. Our data suggests that no reliable, noninvasive method is currently available for detecting and confirming PH in IPF patients. We did not confirm the usefulness of the published formula. Further carefully organised studies will be necessary to verify or refute it
DE-PASS best evidence statement (BESt): determinants of adolescents' device-based physical activity and sedentary behaviour in settings: a systematic review and meta-analysis
Background: Although physical activity (PA) is associated with significant health benefits, only a small percentage of adolescents meet recommended PA levels. This systematic review with meta-analysis explored the modifiable determinants of adolescents' device-based PA and/or sedentary behaviour (SB), evaluated in previous interventions and examined the associations between PA/SB and these determinants in settings.
Methods: A search was conducted on five electronic databases, including papers published from January 2010 to July 2023. Randomized Controlled Trials (RCTs) or Controlled Trials (CTs) measuring adolescents' device-based PA/SB and their modifiable determinants at least at two time points: pre- and post-intervention were considered eligible. PA/SB and determinants were the main outcomes. Modifiable determinants were classified after data extraction adopting the social-ecological perspective. Robust Bayesian meta-analyses (RoBMA) were performed per each study setting. Outcomes identified in only one study were presented narratively. The risk of bias for each study and the certainty of the evidence for each meta-analysis were evaluated. The publication bias was also checked.
Prospero id: CRD42021282874.
Results: Fourteen RCTs (eight in school, three in school and family, and one in the family setting) and one CT (in the school setting) were included. Fifty-four modifiable determinants were identified and were combined into 33 broader determinants (21 individual-psychological, four individual-behavioural, seven interpersonal, and one institutional). RoBMAs revealed none or negligible pooled intervention effects on PA/SB or determinants in all settings. The certainty of the evidence of the impact of interventions on outcomes ranged from very low to low. Narratively, intervention effects in favour of the experimental group were detected in school setting for the determinants: knowledge of the environment for practicing PA, d = 1.84, 95%CI (1.48, 2.20), behaviour change techniques, d = 0.90, 95%CI (0.09, 1.70), choice provided, d = 0.70, 95%CI (0.36, 1.03), but no corresponding effects on PA or SB were found.
Conclusions: Weak to minimal evidence regarding the associations between the identified modifiable determinants and adolescents' device-based PA/SB in settings were found, probably due to intervention ineffectiveness. Well-designed and well-implemented multicomponent interventions should further explore the variety of modifiable determinants of adolescents' PA/SB, including policy and environmental variables.This article is based on work from COST Action CA19101 Determinants of Physical Activities in Settings (DE-PASS), supported by COST (European Cooperation in Science and Technology). The content of this article reflects only the authors’ views and the European Community is not liable for any use that may be made of the information contained therein. COST (European Cooperation in Science and Technology) is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. www.cost.eu
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