An efficient method to include equality constraints in branch current distribution system state estimation

Distribution system state estimation is a fundamental tool for the management and control functions envisaged for future distribution grids. The design of accurate and efficient algorithms is essential to provide estimates compliant with the needed accuracy requirements and to allow the real-time operation of the different applications. To achieve such requirements, peculiarities of the distribution systems have to be duly taken into account. Branch current-based estimators are an efficient solution for performing state estimation in radial or weakly meshed networks. In this paper, a simple technique, which exploits the particular formulation of the branch current estimators, is proposed to deal with zero injection and mesh constraints. Tests performed on an unbalanced IEEE 123-bus network show the capability of the proposed method to further improve efficiency performance of branch current estimators

Grading practices, gender bias and educational outcomes: evidence from Italy

We study if the Italian school system suffers from gender bias when judging students. To this aim, we use a differences-in-differences approach that compares the teachers' assessments and the standardized test scores that the students receive during the school year. We have census data for all Italian fifth and sixth graders in two different subjects, math and language, that include a rich set of additional controls. Our evidence reveals that, since primary school, boys are graded less favourably than girls in both math and language. This result is also confirmed for middle school students (sixth graders), and it holds even when (a) we separate the analysis between the most and least developed Italian regions, (b) we control for possible gender-specific attitude towards cheating and teachers' manipulation and (c) we introduce class and school fixed effects in the models. Comparing the results obtained across different levels of schooling and subjects, we cannot clearly identify the role of specific mechanisms in determining the gender bias. Overall the analysis suggests further study on the role of teachers' characteristics

Investigating pedigree- and SNP-associated components of heritability in a wild population of Soay sheep

Estimates of narrow sense heritability derived from genomic data that contain related individuals may be biased due to the within-family effects such as dominance, epistasis and common environmental factors. However, for many wild populations, removal of related individuals from the data would result in small sample sizes. In 2013, Zaitlen et al. proposed a method to estimate heritability in populations that include close relatives by simultaneously fitting an identity-by-state (IBS) genomic relatedness matrix (GRM) and an identity-by-descent (IBD) GRM. The IBD GRM is identical to the IBS GRM, except relatedness estimates below a specified threshold are set to 0. We applied this method to a sample of 8557 wild Soay sheep from St. Kilda, with genotypic information for 419,281 single nucleotide polymorphisms. We aimed to see how this method would partition heritability into population-level (IBS) and family-associated (IBD) variance for a range of genetic architectures, and so we focused on a mixture of polygenic and monogenic traits. We also implemented a variant of the model in which the IBD GRM was replaced by a GRM constructed from SNPs with low minor allele frequency to examine whether any additive genetic variance is captured by rare alleles. Whilst the inclusion of the IBD GRM did not significantly improve the fit of the model for the monogenic traits, it improved the fit for some of the polygenic traits, suggesting that dominance, epistasis and/or common environment not already captured by the non-genetic random effects fitted in our models may influence these traits.</p

Disability Justice Praxis: Sick, Disabled, Deaf Women and Non-Binary Educators of Color Holding Each Other in Radical Love and Accessible Kinship

Academic spaces in the United States remain exclusive and toxic for those who embody multiple marginalized identities. There is hope, however, as subversive practices and resistance to systemic oppression and hostility continue to infiltrate academia through the work of socially engaged scholar-activists. In this paper, we—four sick, disabled, and Deaf women and non-binary educators of color—come together to discuss our paths to understanding ourselves and our places within academia. Through the methodology of activist ethnography, we explore the diverse and complex ways we embrace Disability Justice in our teaching, research, scholarship, and activism. Collectively and through interwoven storytelling, we disrupt and challenge ableism, racism, settler colonialism, cis-hetero-sexism, classism, and other intersecting forms of oppression within academia by (re)centering and amplifying our lived experiences and disabled, Deaf, and chronically ill epistemologies. Simultaneously, through a Disability Justice praxis, we work to imagine and create educational spaces that build and support radical love, accessible kinship, and healing

Investigating pedigree- and SNP-associated components of heritability in a wild population of Soay sheep

Estimates of narrow sense heritability derived from genomic data that contain related individuals may be biased due to the within-family effects such as dominance, epistasis and common environmental factors. However, for many wild populations, removal of related individuals from the data would result in small sample sizes. In 2013, Zaitlen et al. proposed a method to estimate heritability in populations that include close relatives by simultaneously fitting an identity-by-state (IBS) genomic relatedness matrix (GRM) and an identity-by-descent (IBD) GRM. The IBD GRM is identical to the IBS GRM, except relatedness estimates below a specified threshold are set to 0. We applied this method to a sample of 8557 wild Soay sheep from St. Kilda, with genotypic information for 419,281 single nucleotide polymorphisms. We aimed to see how this method would partition heritability into population-level (IBS) and family-associated (IBD) variance for a range of genetic architectures, and so we focused on a mixture of polygenic and monogenic traits. We also implemented a variant of the model in which the IBD GRM was replaced by a GRM constructed from SNPs with low minor allele frequency to examine whether any additive genetic variance is captured by rare alleles. Whilst the inclusion of the IBD GRM did not significantly improve the fit of the model for the monogenic traits, it improved the fit for some of the polygenic traits, suggesting that dominance, epistasis and/or common environment not already captured by the non-genetic random effects fitted in our models may influence these traits.</p

The impact of SNP density on quantitative genetic analyses of body size traits in a wild population of Soay sheep

Understanding the genetic architecture underpinning quantitative traits in wild populations is pivotal to understanding the processes behind trait evolution. The ‘animal model’ is a popular method for estimating quantitative genetic parameters such as heritability and genetic correlation and involves fitting an estimate of relatedness between individuals in the study population. Genotypes at genome‐wide markers can be used to estimate relatedness; however, relatedness estimates vary with marker density, potentially affecting results. Increasing density of markers is also expected to increase the power to detect quantitative trait loci (QTL). In order to understand how the density of genetic markers affects the results of quantitative genetic analyses, we estimated heritability and performed genome‐wide association studies (GWAS) on five body size traits in an unmanaged population of Soay sheep using two different SNP densities: a dataset of 37,037 genotyped SNPs and an imputed dataset of 417,373 SNPs. Heritability estimates did not differ between the two SNP densities, but the high‐density imputed SNP dataset revealed four new SNP‐trait associations that were not found with the lower density dataset, as well as confirming all previously‐found QTL. We also demonstrated that fitting fixed and random effects in the same step as performing GWAS is a more powerful approach than pre‐correcting for covariates in a separate model

Cross‑country diferences in drivers of female necessity entrepreneurship

This paper analyzes the drivers of female necessity entrepreneurship using a sample of 59 countries, with data sourced from the 2018-2019 global entrepreneurship monitor (GEM). It develops a theoretical framework describing how post-secondary education, startup skills, fear of failure, knowing another entrepreneur, entrepreneurial intentions, and hiring expectations act as drivers of female necessity entrepreneurship. Using qualitative comparative analysis, two models are tested to explain the presence and absence of female necessity entrepreneurship. This outcome is measured using the GEM indicator of total early-stage entrepreneurial activit

Centralized flexibility services for distribution system operators through distributed flexible resources

Under the context of smart grids within smart cities, increasing distributed generation, consumer empowerment and emerging flexibility services, distribution system operators could benefit by activating flexibility in distribution grids to avoid deploying new infrastructures and grid overloading. The solution offered by this work is an energy management system algorithm capable of activating flexibility behind the prosumer main meter during constrained periods. Therefore, the distribution system operator could compensate grid congestion during high consumption or production periods and increase their renewable generation hosting capacity by using behind-the-meter flexibility during peak production periods.Postprint (published version

A novel strategy to enhance interfacial adhesion in fiber-reinforced calcium phosphate cement

Calcium phosphate cements (CPCs) are extensively used as synthetic bone grafts, but their poor toughness limits their use to non-load-bearing applications. Reinforcement through introduction of fibers and yarns has been evaluated in various studies but always resulted in a decrease in elastic modulus or bending strength when compared to the CPC matrix. The aim of the present work was to improve the interfacial adhesion between fibers and matrix to obtain tougher biocompatible fiber-reinforced calcium phosphate cements (FRCPCs). This was done by adding a polymer solution to the matrix, with chemical affinity to the reinforcing chitosan fibers, namely trimethyl chitosan (TMC). The improved wettability and chemical affinity of the chitosan fibers with the TMC in the liquid phase led to an enhancement of the interfacial adhesion. This resulted in an increase of the work of fracture (several hundred-fold increase), while the elastic modulus and bending strength were maintained similar to the materials without additives. Additionally the TMC-modified CPCs showed suitable biocompatibility with an osteoblastic cell line.Preprin