Applying chaos theory to human resource development.

As organizations increasingly recognize the shortcomings of scientific management approaches and traditional top-down approaches to change, there is an increasing openness to new lenses for understanding change. Chaos Theory, with its roots in the natural sciences, provides a holistic approach for understanding the dynamic and fluid nature of organizations. This paper provides a review of literature that outlines the origins and basic principles of Chaos Theory, applies the concepts to organizations, and connects the concept to human resource development

Codon usage bias and tRNA over-expression in Buchnera aphidicola after aromatic amino acid nutritional stress on its host Acyrthosiphon pisum

Codon usage bias and relative abundances of tRNA isoacceptors were analysed in the obligate intracellular symbiotic bacterium, Buchnera aphidicola from the aphid Acyrthosiphon pisum, using a dedicated 35mer oligonucleotide microarray. Buchnera is archetypal of organisms living with minimal metabolic requirements and presents a reduced genome with high-evolutionary rate. Codonusage in Buchnera has been overcome by the high mutational bias towards AT bases. However, several lines of evidence for codon usage selection are given here. A significant correlation was found between tRNA relative abundances and codon composition of Buchnera genes. A significant codon usage bias was found for the choice of rare codons in Buchnera: C-ending codons are preferred in highly expressed genes, whereas G-ending codons are avoided. This bias is not explained by GC skew in the bacteria and might correspond to a selection for perfect matching between codon–anticodon pairs for some essential amino acids in Buchnera proteins. Nutritional stress applied to the aphid host induced a significant overexpression of most of the tRNA isoacceptors in bacteria. Although, molecular regulation of the tRNA operons in Buchnera was not investigated, a correlation between relative expression levels and organization in transcription unit was found in the genome of Buchnera

Enjoymen, Boredom, and Anxiety in the Spanish Language Classroom

This study analyzes the nature and links between enjoyment, boredom, and anxiety in the Spanish language classroom at the university level. The students participating in the study were enrolled in courses of Spanish for heritage speakers and Spanish as a foreign language (heritage and non-heritage students). Qualitative and quantitative data were collected simultaneously, analyzed separately (articles 1 and 2 respectively), and combined (article 3). A survey with Likert scale questions was used to collect the quantitative data. Enjoyment, boredom, and anxiety were the dependent variables, and the independent variables were heritage speakers in heritage and regular Spanish courses and non-heritage speakers in regular Spanish courses. Article 1 found that there was a negative correlation between FLE and FLB, and FLCA and FLE. Article 2 discovered the causes of enjoyment in the Spanish language class were instructor's teaching style as well as interesting, relatable, and engaging material. For boredom for HLLs and FLLs in FLCs the causes were both lecture heavy classes with no interaction and dislike of course materials. Being called on to participate was the primary cause of anxiety for FLLs. Oral presentations and tests were the primary causes for HLLs in HLCs, while feeling judged was the cause for HLLs in FLCs. Article 3 found that sociobiographical factors, such as socialization with Hispanic/Latinx, society’s expectations, language spoken (English), and gender (male) were predictors for enjoyment, anxiety, and boredom in both groups

Modelling and Simulation of Hydrogen Electrolyzers for Power System Applications

The rapid increase in the share of intermittent renewables in the energy mix is exacerbating the complexity of the grid stability. To facilitate the inclusion of these green technologies and achieve the climate targets set by the EU, the generation and storage of hydrogen through electrolysis may be crucial. Moreover, the hydrogen can later be used as a replacement for polluting components in several industries, helping to reduce the CO2 emissions. In order to be able to couple the hydrogen electrolyzers with the grid, accurate models need to be developed, where all the physical characteristics and the empirical behavior of the cells are encapsuled. Hence, this thesis will explore the different models available in the literature for the three main technologies of electrolyzers: proton exchange membrane (PEMEC), alkaline (AEC) and solid oxide cells (SOEC). Even though the alkaline is the most mature and established technology, the aforementioned exhibit important features, such as faster response times or lower electricity requirements, that may enable them to overtake alkaline electrolyzers in terms of presence in the grid support services. The models are reproduced and compared using MATLAB/Simulink so that a clear overview of the current state of the electrolyzers and the ground for their expansion is prepared. Three core modalities are examined: electrochemical equations, electrical analogues and thermal submodels. The equations are found to reliably replicate the behavior obtained in the experiments. Meanwhile, the thermal influence is usually often disregarded due to the significantly slower rate at which temperature changes occur compared to the response times of the electrical signals. So far, SOEC are still in development so a clear electrical modelling is yet not available, however, for the already commercial PEMEC and AEC, several different equivalent circuits can be found. The models show good agreement with the experimental data, being the PEMEC faster in response and having a higher degree of degradation rate.Den snabba ökningen av andelen intermittent förnybar energi i energimixen förvärrar komplexiteten i nätstabiliteten. För att underlätta inkluderingen av dessa gröna tekniker och uppnå de klimatmål som EU har satt upp kan generering och lagring av väte genom elektrolys vara avgörande. Dessutom kan vätet senare användas som ersättning för förorenande komponenter i flera industrier, vilket bidrar till att minska CO2- utsläppen. För att kunna koppla ihop väteelektrolysörerna med nätet behöver noggranna modeller utvecklas, där alla fysiska egenskaper och det empiriska beteendet hos cellerna är inkapslade. Därför kommer denna avhandling att utforska de olika modellerna som finns tillgängliga i litteraturen för de tre huvudteknologierna för elektrolysatorer: protonbytesmembran (PEMEC), alkaliska (AEC) och fasta oxidceller (SOEC). Även om den alkaliska är den mest mogna och etablerade tekniken, uppvisar ovan nämnda viktiga egenskaper, såsom snabbare svarstider eller lägre elkrav, som kan göra det möjligt för dem att köra om alkaliska elektrolysörer när det gäller närvaro i nätets supporttjänster. Modellerna reproduceras och jämförs med MATLAB/Simulink så att en tydlig överblick över elektrolysatorernas nuvarande tillstånd och marken för deras expansion förbereds. Tre kärnmodaliteter undersöks: elektrokemiska ekvationer, elektriska analoger och termiska delmodeller. Ekvationerna visar sig på ett tillförlitligt sätt replikera beteendet som erhölls i experimenten. Samtidigt bortses vanligtvis ofta från den termiska påverkan på grund av den betydligt långsammare hastigheten med vilken temperaturförändringar sker jämfört med svarstiderna för de elektriska signalerna. Än så länge är SOEC fortfarande under utveckling så en tydlig elektrisk modellering är ännu inte tillgänglig, men för de redan kommersiella PEMEC och AEC kan flera olika likvärdiga kretsar hittas. Modellerna visar god överensstämmelse med experimentdata, eftersom de är PEMEC snabbare som svar och har en högre grad av nedbrytningshastighe

Applying chaos theory to human resource development.

As organizations increasingly recognize the shortcomings of scientific management approaches and traditional top-down approaches to change, there is an increasing openness to new lenses for understanding change. Chaos Theory, with its roots in the natural sciences, provides a holistic approach for understanding the dynamic and fluid nature of organizations. This paper provides a review of literature that outlines the origins and basic principles of Chaos Theory, applies the concepts to organizations, and connects the concept to human resource development

Chromosome organisation in Buchnera: a dynamic active structure involved in gene expression regulation

International audienceMost bacterial chromosomes consist of a single closed-circular DNA molecule folded into a compact and dynamic structure called the nucleoid. Variations of chromosome 3D-structure act as a global regulatory factor of gene expression. More particularly, the modulation of genome architecture is admitted to belong to the class of mechanisms allowing genome-wide transcriptional profile variation in response to environmental changes [1, 2].We searched for evidences of spatial organization of the chromosome in an extremely intriguing bacterial model: Buchnera aphidicola. Associated with most agricultural pest aphids and being partly responsible for their harmfulness, Buchnera are one of the most studied intracellular symbiotic bacteria of insects. Their genomes present all the characteristics of intracellular bacteria: (1) small size of 400 - 600 kb depending on aphid species, (2) highly biased base composition towards A and T and (3) high evolutionary rate due to the isolation of Buchnera populations within the host cells combined with the drastic bottlenecks that occur in the population dynamics of the bacteria during their transmission to the aphid progeny.A crucial stage for the symbiosis comprehension passes through the understanding of symbiont gene expression regulation, and yet little is known about the transcriptional regulation capabilities of the bacteria. Given the “poor” catalogue of transcriptional factors it was suggested that the bacteria are no longer able to regulate their gene expression. Also, Buchnera conserved target genes for regulatory proteins absent in their genome. Nevertheless, recent works using a dedicated microarray showed that Buchnera respond specifically to somenutritional stresses imposed to their host [3].The aim of this work was to study potential structural units of the Buchnera chromosome and the impact they could have on the gene expression regulation. For this purpose, we analysed the potential structural domains of the chromosome at different scales and the main contributor proteins for the organization and maintenance of these domains. Our study brings evidences for (1) the existence of structural chromosomal units at several scales, (2) a functionally complete set of proteins essential for nucleoid organization and (3) the tight interdependence between these proteins, the chromosome architecture and the gene expression profile.Basic genomic structural elements in bacteria participating to the chromosome organization are transcription units (operons). A transcription unit contains one or several adjacent genes transcribed as a single mRNA. Thus, genes belonging to the same transcriptional unit display strong correlated transcription levels. A first annotation of Buchnera transcription units was available in BioCyc (http://biocyc.org/). We found that some of these transcriptional units were not consistent with the analysis of the gene expression profile. Thus, we decided to re-annotate the transcription units of Buchnera taking into account gene expression levels, gene order conservation, sequence features of Buchnera, like Rho-independent terminators inferred by the bioinformatics tool (TransTermHP, [4]) and specific intergenic distances. We tested this new annotation with microarray gene expression data.A higher level of structural units in bacterial genomes is represented by the organization in topological domains (~10kbp in E. coli [5]). These structures are mainly organized and maintained by Nucleoid Associated Proteins (NAPs). Analysis of the NAP set of Buchnera pointed out that, despite genome reduction, the bacteria retains the most important members of the group (IHF, H-NS, Fis, DnaA and HU). Our bioinformatics analysis of these proteins confirms a strong conservation of structural domains and 3D structure. Moreover, key amino acids (their mutation compromises NAPs function in E. coli) are also well conserved. As NAPs must frequently bind DNA (every 10 kbp) to form dynamic inter-domains barriers, they rather recognize specific topologic structures (i.e., bend DNA) than specific motive binding sites. By using Curvature program [6]), we showed that Buchnera have a more curved DNA than E. coli (this result may be partially explained by the strong A-T bias) , that might influence the size and shape of their topological domains.Combination of topological domains and DNA fold are at the origin of a third class of larger structural units in bacterial chromosomes. Previous results of our team pointed out a periodic transcriptional pattern that supports the existence of these kinds of structures in Buchnera [7]. We completed this work by using a more realistic distance on the chromosome (i.e., physical distance (bp), instead of the “gene number” distance).Our work brings several evidences that Buchnera chromosome is a functional structure probably playing an active role in gene expression regulation. This kind of regulation was often neglected in free-living bacteria but might be central in shrunken genomes of endosymbionts. A short-term perspective of our work will be to inactivate in vivo specific NAP proteins of Buchnera and analyse the induced modifications within the gene expression profile of the symbiotic bacteria

Chromosome organisation in Buchnera: a dynamic active structure involved in gene expression regulation

International audienceMost bacterial chromosomes consist of a single closed-circular DNA molecule folded into a compact and dynamic structure called the nucleoid. Variations of chromosome 3D-structure act as a global regulatory factor of gene expression. More particularly, the modulation of genome architecture is admitted to belong to the class of mechanisms allowing genome-wide transcriptional profile variation in response to environmental changes [1, 2].We searched for evidences of spatial organization of the chromosome in an extremely intriguing bacterial model: Buchnera aphidicola. Associated with most agricultural pest aphids and being partly responsible for their harmfulness, Buchnera are one of the most studied intracellular symbiotic bacteria of insects. Their genomes present all the characteristics of intracellular bacteria: (1) small size of 400 - 600 kb depending on aphid species, (2) highly biased base composition towards A and T and (3) high evolutionary rate due to the isolation of Buchnera populations within the host cells combined with the drastic bottlenecks that occur in the population dynamics of the bacteria during their transmission to the aphid progeny.A crucial stage for the symbiosis comprehension passes through the understanding of symbiont gene expression regulation, and yet little is known about the transcriptional regulation capabilities of the bacteria. Given the “poor” catalogue of transcriptional factors it was suggested that the bacteria are no longer able to regulate their gene expression. Also, Buchnera conserved target genes for regulatory proteins absent in their genome. Nevertheless, recent works using a dedicated microarray showed that Buchnera respond specifically to somenutritional stresses imposed to their host [3].The aim of this work was to study potential structural units of the Buchnera chromosome and the impact they could have on the gene expression regulation. For this purpose, we analysed the potential structural domains of the chromosome at different scales and the main contributor proteins for the organization and maintenance of these domains. Our study brings evidences for (1) the existence of structural chromosomal units at several scales, (2) a functionally complete set of proteins essential for nucleoid organization and (3) the tight interdependence between these proteins, the chromosome architecture and the gene expression profile.Basic genomic structural elements in bacteria participating to the chromosome organization are transcription units (operons). A transcription unit contains one or several adjacent genes transcribed as a single mRNA. Thus, genes belonging to the same transcriptional unit display strong correlated transcription levels. A first annotation of Buchnera transcription units was available in BioCyc (http://biocyc.org/). We found that some of these transcriptional units were not consistent with the analysis of the gene expression profile. Thus, we decided to re-annotate the transcription units of Buchnera taking into account gene expression levels, gene order conservation, sequence features of Buchnera, like Rho-independent terminators inferred by the bioinformatics tool (TransTermHP, [4]) and specific intergenic distances. We tested this new annotation with microarray gene expression data.A higher level of structural units in bacterial genomes is represented by the organization in topological domains (~10kbp in E. coli [5]). These structures are mainly organized and maintained by Nucleoid Associated Proteins (NAPs). Analysis of the NAP set of Buchnera pointed out that, despite genome reduction, the bacteria retains the most important members of the group (IHF, H-NS, Fis, DnaA and HU). Our bioinformatics analysis of these proteins confirms a strong conservation of structural domains and 3D structure. Moreover, key amino acids (their mutation compromises NAPs function in E. coli) are also well conserved. As NAPs must frequently bind DNA (every 10 kbp) to form dynamic inter-domains barriers, they rather recognize specific topologic structures (i.e., bend DNA) than specific motive binding sites. By using Curvature program [6]), we showed that Buchnera have a more curved DNA than E. coli (this result may be partially explained by the strong A-T bias) , that might influence the size and shape of their topological domains.Combination of topological domains and DNA fold are at the origin of a third class of larger structural units in bacterial chromosomes. Previous results of our team pointed out a periodic transcriptional pattern that supports the existence of these kinds of structures in Buchnera [7]. We completed this work by using a more realistic distance on the chromosome (i.e., physical distance (bp), instead of the “gene number” distance).Our work brings several evidences that Buchnera chromosome is a functional structure probably playing an active role in gene expression regulation. This kind of regulation was often neglected in free-living bacteria but might be central in shrunken genomes of endosymbionts. A short-term perspective of our work will be to inactivate in vivo specific NAP proteins of Buchnera and analyse the induced modifications within the gene expression profile of the symbiotic bacteria

Genomic DNA: an attractive candidate for microarray data normalization

5-COM (communications sans actes

Relationship between gene expression and genome properties in Buchnera aphidicola, the primary endosymbiont of the pea aphid Acyrthosiphon pisum

5-COM (communications sans actes