A Reliability-Generalization Study of Journal Peer Reviews: A Multilevel Meta-Analysis of Inter-Rater Reliability and Its Determinants

Background: This paper presents the first meta-analysis for the inter-rater reliability (IRR) of journal peer reviews. IRR is defined as the extent to which two or more independent reviews of the same scientific document agree. Methodology/Principal Findings: Altogether, 70 reliability coefficients (Cohen’s Kappa, intra-class correlation [ICC], and Pearson product-moment correlation [r]) from 48 studies were taken into account in the meta-analysis. The studies were based on a total of 19,443 manuscripts; on average, each study had a sample size of 311 manuscripts (minimum: 28, maximum: 1983). The results of the meta-analysis confirmed the findings of the narrative literature reviews published to date: The level of IRR (mean ICC/r 2 =.34, mean Cohen’s Kappa =.17) was low. To explain the study-to-study variation of the IRR coefficients, meta-regression analyses were calculated using seven covariates. Two covariates that emerged in the metaregression analyses as statistically significant to gain an approximate homogeneity of the intra-class correlations indicated that, firstly, the more manuscripts that a study is based on, the smaller the reported IRR coefficients are. Secondly, if the information of the rating system for reviewers was reported in a study, then this was associated with a smaller IRR coefficient than if the information was not conveyed. Conclusions/Significance: Studies that report a high level of IRR are to be considered less credible than those with a low level o

Comparative analysis of amplicon and metagenomic sequencing methods reveals key features in the evolution of animal metaorganisms

Background The interplay between hosts and their associated microbiome is now recognized as a fundamental basis of the ecology, evolution, and development of both players. These interdependencies inspired a new view of multicellular organisms as “metaorganisms.” The goal of the Collaborative Research Center “Origin and Function of Metaorganisms” is to understand why and how microbial communities form long-term associations with hosts from diverse taxonomic groups, ranging from sponges to humans in addition to plants. Methods In order to optimize the choice of analysis procedures, which may differ according to the host organism and question at hand, we systematically compared the two main technical approaches for profiling microbial communities, 16S rRNA gene amplicon and metagenomic shotgun sequencing across our panel of ten host taxa. This includes two commonly used 16S rRNA gene regions and two amplification procedures, thus totaling five different microbial profiles per host sample. Conclusion While 16S rRNA gene-based analyses are subject to much skepticism, we demonstrate that many aspects of bacterial community characterization are consistent across methods. The resulting insight facilitates the selection of appropriate methods across a wide range of host taxa. Overall, we recommend single- over multi-step amplification procedures, and although exceptions and trade-offs exist, the V3 V4 over the V1 V2 region of the 16S rRNA gene. Finally, by contrasting taxonomic and functional profiles and performing phylogenetic analysis, we provide important and novel insight into broad evolutionary patterns among metaorganisms, whereby the transition of animals from an aquatic to a terrestrial habitat marks a major event in the evolution of host-associated microbial composition

Membrane- and plate-type acoustic metamaterials with elastic unit cell edges

Membrane- and plate-type acoustic metamaterials are thin membranes or plates consisting of periodic unit cells with small added masses. It has been shown in numerous studies, that these metamaterials exhibit tunable anti-resonances with transmission loss values much higher than the corresponding mass-law. However, in most studies it is assumed that the unit cell edges (or grid) of the metamaterial are fixed. This idealised boundary condition is not applicable to real world applications in noise control. Therefore, the acoustic performance of these metamaterials under more realistic circumstances, where the grid structure cannot be perfectly rigid, can be expected to be different. In this contribution, the vibro-acoustic behavior of membrane- and plate-type acoustic metamaterials with a non-rigid grid is investigated. For this purpose, an efficient analytical model is developed to predict the eigenmodes and sound transmission loss of such metamaterials. In this model, elastic unit cell edges are modelled using a grid of Euler-Bernoulli beams and the sound transmission loss can be calculated for oblique incidence. A comparison to FEM simulations shows that the proposed model yields the same results but with a considerably reduced computational effort. The analytical model is then used to discuss the vibro-acoustic properties of the metamaterial, with particular focus on the influence of the mass and stiffness of the grid beams. It is shown that even when a non-rigid grid and diffuse incident sound fields are considered, the transmission loss of the metamaterial exhibits anti-resonances with remarkably high noise reduction values. These anti-resonances can be tuned by choosing appropriate values of the grid parameters. Furthermore, the formation of band gaps in the propagation of bending waves is discussed by investigating the dispersion curves of the metamaterial. The results in this contribution show that membrane- and plate-type acoustic metamaterials can still efficiently reduce low-frequency noise, even when the unit cell edges are not assumed to be fixed. This important finding and the proposed analytical modal can support the utilization of these metamaterials in practical noise control applications.</p

Schalldämmende Struktur mit integrierten Membran-Metamaterialien und Absorbern

(HAW 074), Erfindungsmeldung vom 10.03.201

Struktur zur Schalldämmung und Schallabsorption mit einer durchlochten Struktur und Massen

(HAW 075), Erfindungsmeldung vom 29.03.201

Schalldämmeinrichtung mit integrierten Elementen mit negativer Steifigkeit

(HAW 090), Erfindungsmeldung vom 07.09.201

Broadband low-frequency sound transmission loss improvement of double walls with Helmholtz resonators

Helmholtz resonators are commonly used as narrowband sound absorbers in room acoustics applications. Previous research has shown that Helmholtz resonators can also be used to improve the sound transmission loss of double walls. The focus of this paper is the broadband improvement of the transmission loss of double walls in the low frequency region by tuning the Helmholtz resonators inside the cavity to frequencies lower or higher than the mass-air-mass resonance frequency of the double wall. A new analytical model using the effective material parameters (bulk modulus and density) of a fluid volume containing Helmholtz resonators is developed to describe the vibro-acoustic behavior of double walls with Helmholtz resonators. Using this model it can be shown that by tuning the Helmholtz resonators properly, the mass-air-mass resonance frequency of the unmodified double wall can be shifted significantly, leading to an improvement of the transmission loss of the double wall roughly between the mass-air-mass resonance frequency and the resonance frequency of the resonators. This improvement, however, comes along with a decrease of the transmission loss at high frequencies due to a decoupling of the Helmholtz resonators which is also covered by the proposed analytical model. Parametric studies are performed to identify relevant design parameters to optimize the transmission loss improvement by the Helmholtz resonators. Finally, experimental results of different double wall designs with integrated Helmholtz resonators are presented to validate the proposed analytical model and demonstrate the effectiveness under diffuse field incidence

Schallabsorber mit schwingfähigen Strukturen

(HAW 093), Erfindungsmeldung vom 15.11.201

Resonance frequencies and sound absorption of Helmholtz resonators with multiple necks

A new analytical model is proposed to calculate the resonance frequency and the input impedance of a Helmholtz resonator with multiple necks. Such resonators occur in practice, for example, when leaks are introduced as additional necks inside the wall of the resonators. The model uses a lumped representation of the air volumes enclosed by the necks to derive an explicit formula for the resonance frequency. Using this formula, it can be explained that the low reactance of the air volumes inside leaks of thin-walled Helmholtz resonators leads to the strong increase of the resonance frequency, as observed in previous studies. The results of the analytical model are validated with the help of experimental data available in the literature and impedance tube measurements. The analytical model as well as the measurements clearly show, that even small holes in the Helmholtz resonator lead to a significant increase in the resonance frequency and the absorption performance can be considerably reduced. The simple model can be applied to design Helmholtz resonators with multiple necks or estimate the impact of leaks.</p