Magnetic transitions in Pr2NiO4 single crystal

The magnetic properties of a stoichiometric Pr2NiO4 single crystal have been examined by means of the temperature dependence of the complex ac susceptibility and the isothermal magnetization in fields up to 200 kOe at T=4.2 K. Three separate phases have been identified and their anisotropic character has been analyzed. A collinear antiferromagnetic phase appears first between TN = 325 K and Tc1 = 115 K, where the Pr ions are polarized by an internal magnetic field. At Tc1 a first modification of the magnetic structure occurs in parallel with a structural phase transition (Bmab to P42/ncm). This magnetic transition has a first‐order character and involves both the out‐of‐plane and the in‐plane spin components (magnetic modes gx and gxcyfz, respectively). A second magnetic transition having also a first‐order character is also clearly identified at Tc2 = 90 K which corresponds to a spin reorientation process (gxcyfz to cxgyaz magnetic modes). It should be noted as well that the out‐of‐phase component of χac shows a peak around 30 K which reflects the coexistence of both magnetic configurations in a wide temperature interval. Finally, two field‐induced transitions have been observed at 4.2 K when the field is directed along the c axis. We propose that the high‐field anomaly arises from a metamagnetic transition of the weak ferromagnetic component, similarly to La2CuO4

The Cross-Cultural Invariance of the Servant Leadership Survey: A Comparative Study across Eight Countries

This paper tests and confirms the cross-cultural equivalence of the Servant Leadership Survey (SLS) in eight countries and languages: The Netherlands, Portugal, Germany, Iceland, Italy, Spain, Turkey and Finland. A composite sample consisting of 5201 respondents from eight countries that all filled out the SLS was used. A three-step approach was adopted to test configural invariance, measurement equivalence, and structural equivalence. For the full 30-item version of the SLS, configural invariance and partial measurement equivalence were confirmed. Implications of these results for the use of the SLS within cross-cultural studies are discussed

Evaluation of Existing Methods for High-Order Epistasis Detection

[Abstract] Finding epistatic interactions among loci when expressing a phenotype is a widely employed strategy to understand the genetic architecture of complex traits in GWAS. The abundance of methods dedicated to the same purpose, however, makes it increasingly difficult for scientists to decide which method is more suitable for their studies. This work compares the different epistasis detection methods published during the last decade in terms of runtime, detection power and type I error rate, with a special emphasis on high-order interactions. Results show that in terms of detection power, the only methods that perform well across all experiments are the exhaustive methods, although their computational cost may be prohibitive in large-scale studies. Regarding non-exhaustive methods, not one could consistently find epistasis interactions when marginal effects are absent. If marginal effects are present, there are methods that perform well for high-order interactions, such as BADTrees, FDHE-IW, SingleMI or SNPHarvester. As for false-positive control, only SNPHarvester, FDHE-IW and DCHE show good results. The study concludes that there is no single epistasis detection method to recommend in all scenarios. Authors should prioritize exhaustive methods when sufficient computational resources are available considering the data set size, and resort to non-exhaustive methods when the analysis time is prohibitive.10.13039/501100010801-Xunta de Galicia (Grant Number: ED431C2016-037, ED431C2017/04 and ED431G2019/01) 10.13039/501100003176-Ministerio de Educacion Cultura y Deporte (Grant Number: FPU16/01333) 10.13039/501100003329-Ministerio de Economia y Competitividad (Grant Number: CGL2016-75482-P, PID2019-104184RB-I00, AEI/FEDER/EU, 10.13039/50110 and TIN2016-75845-P)Xunta de Galicia; ED431C2016-037Xunta de Galicia; ED431G2019/01Xunta de Galicia; ED431C 2017/0

Toxo: A Library for Calculating Penetrance Tables of High-Order Epistasis Models

[Abstract] Background Epistasis is defined as the interaction between different genes when expressing a specific phenotype. The most common way to characterize an epistatic relationship is using a penetrance table, which contains the probability of expressing the phenotype under study given a particular allele combination. Available simulators can only create penetrance tables for well-known epistasis models involving a small number of genes and under a large number of limitations. Results Toxo is a MATLAB library designed to calculate penetrance tables of epistasis models of any interaction order which resemble real data more closely. The user specifies the desired heritability (or prevalence) and the program maximizes the table’s prevalence (or heritability) according to the input epistatic model boundaries. Conclusions Toxo extends the capabilities of existing simulators that define epistasis using penetrance tables. These tables can be directly used as input for software simulators such as GAMETES so that they are able to generate data samples with larger interactions and more realistic prevalences/heritabilities.This research was supported by the Ministry of Economy and Competitiveness of Spain (CGL2016-75482-P), the Ministry of Economy and Competitiveness of Spain and FEDER funds of the EU (TIN2016-75845-P), the Xunta de Galicia (Grupo de Referencia Competitiva, ED431C2016-037), the Xunta de Galicia and FEDER funds of the EU (Centro de Investigación de Galicia accreditation 2019-2022, ref. ED431G2019/01), Consolidation Program of Competitive Research (ED431C 2017/04) and the FPU Program of the Ministry of Education of Spain (FPU16/01333)Xunta de Galicia; ED431C2016-037Xunta de Galicia; ED431G2019/01Xunta de Galicia; ED431C 2017/0

Magnetic order and multipole interactions in CexPr1-xB6 solid solutions

Magnetic ordering phenomena in CexPr1-xB6 solid solutions have been studied using both powder and single-crystal neutron diffraction. A variety of magnetic structures are observed depending on temperature and Ce concentration. Over a broad composition range (x $\le$ 0.7), Pr-Pr interactions play a dominant role, giving rise to incommensurate structures with wave vectors of the form k{IC1}=(1/4-delta, 1/4, 1/2) or k{IC2}=(1/4-delta, 1/4-delta, 1/2). The crossover to a CeB6-like regime takes place near x = 0.7-0.8. For the latter composition, the antiferroquadrupolar phase transition observed in transport measurements precedes the onset, at lower temperature, of a commensurate magnetic order similar to that existing in CeB6. However, unlike in the pure compound, an incommensurate magnetic order is formed at even higher temperature and persists in the antiferroquadrupolar phase down to the lock-in transition. These results are shown to reflect the interplay between various type of dipole exchange and higher multipole interactions in this series of compounds.Comment: Abstract of submission changed to get rid of LaTeX code Minor differences exist between this version and that published in PRB (corrections introduced by publisher

A low-voltage low-power front-end for wearable EEG systems

A low-voltage and low-power front-end for miniaturized, wearable EEG systems is presented. The instrumentation amplifier, which removes the electrode drift and conditions the signal for a 10-bit A/D converter, combines a chopping strategy with quasi-FGMOS (QFG) transistors to minimize low frequency noise whilst enabling operation at 1 V supply. QFG devices are also key to the A/D converter operating at 1.2 V with 70dB of SNR and an oversampling ratio of 64. The whole system consumes less than 2uW at 1.2V.Published versio

Assessing Significance in High-Throughput Experiments by Sequential Goodness of Fit and q-Value Estimation

We developed a new multiple hypothesis testing adjustment called SGoF+ implemented as a sequential goodness of fit metatest which is a modification of a previous algorithm, SGoF, taking advantage of the information of the distribution of p-values in order to fix the rejection region. The new method uses a discriminant rule based on the maximum distance between the uniform distribution of p-values and the observed one, to set the null for a binomial test. This new approach shows a better power/pFDR ratio than SGoF. In fact SGoF+ automatically sets the threshold leading to the maximum power and the minimum false non-discovery rate inside the SGoF' family of algorithms. Additionally, we suggest combining the information provided by SGoF+ with the estimate of the FDR that has been committed when rejecting a given set of nulls. We study different positive false discovery rate, pFDR, estimation methods to combine q-value estimates jointly with the information provided by the SGoF+ method. Simulations suggest that the combination of SGoF+ metatest with the q-value information is an interesting strategy to deal with multiple testing issues. These techniques are provided in the latest version of the SGoF+ software freely available at http://webs.uvigo.es/acraaj/SGoF.htm

High-pressure synthesis of rock salt LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions

Metastable LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions with rock salt crystal structure have been synthesized by solid state reaction of ZnO with LiMeO2 complex oxides at 7.7 GPa and 1350-1450 K. Structure, phase composition, thermal stability and thermal expansion of the recovered samples have been studied by X-ray diffraction with synchrotron radiation. At ambient pressure rock salt LiMeO2-ZnO solid solutions are kinetically stable up to 670-800 K depending on the composition.Comment: 11 pages, 3 figures, 1 tabl