Change point algorithms appliedto the detection of vortex structures in turbulent flows

En este trabajo se presenta el análisis de la aplicación del modelo de un algoritmo de punto de cambio (Change Point Model, CPM), basado en tests no paramétricos, para la detección de estructuras turbulentas en un flujo de aire. Se busca detectar los vórtices generados en la estela de un perfil aerodinámico dotado de un dispositivo de control pasivo de flujo (mini flap de Gurney) ubicado en el borde de fuga. De la muestra de datos obtenida se analiza la aplicación de modelos CPM, con el fin de determinar los posibles cambios de la fluctuación de la velocidad sensada, comparando los resultados con análisis tradicionales. El objetivo principal del estudio es el de detectar las frecuencias características de las estructuras turbulentas inmersas en el campo del flujo. De los resultados obtenidos se desprende que el modelo CPM basado en el test de Cramer-von Mises (CPM-CvM) presenta una buena concordancia con las detecciones esperadas (diferencias menores al 9,5%), mostrando ser una herramienta alternativa para el análisis de estos tipos de flujo en tiempo real. Este trabajo muestra, finalmente, una nueva aplicación para CPM en la detección de cambios en señales aleatorias dependientes del tiempo que tienen una distribución, a priori, desconocida.The present work shows the application of a change point model (CPM) algorithm, based on non-parametric tests, to turbulent structures detection in an airflow. It seeks to detect the vortices generated in the wake of an airfoil, equipped with a passive flow control device (Gurney mini flap) in its trailing edge. By applying CPM models to the sample data, this paper seeks to determine the possible changes to the velocity fluctuations and compare the models effectiveness to traditional methods. The main objective of this study is to detect the characteristic frequencies of the turbulent structures immersed in the airflow. The results show that the CPM methodology, based on the Cramer- von Mises (CPM-CvM) test, produces results that coincide with values predicted by traditional methods (less than 9.5% of mismatch), validating its use as a real time alternative tool for the analysis of these types of flows. Finally, this work shows a new application of CPM for detecting changes in a timedependent random signal, which has an a priori unknown distribution.Peer Reviewe

The motherhood penalties : insights from women in UK academia

We use an original survey of academic women in the UK to investigate different dimensions of the motherhood penalty. Being a mother has no effect on salaries, but still slows down career progression even in such a high-skilled sector. Motherhood has an ambivalent impact on women’s perception of their working environment: improving satisfaction, but reducing perception of salary fairness relative to men. Our paper also explores how different policies can mitigate the motherhood penalties. We find that more generous maternity provisions are associated with higher salary, potentially because generosity reduces the crowding out of research activity. Better availability of childcare and an even distribution of responsibilities within the household correlate positively with earnings. Our findings also highlight the importance of a supportive work environment for mothers’ career and well-being at the workplace. Taken together, these findings suggest the necessity of a multi-faceted policy response to the motherhood penalties

Motherhood in academia : a novel dataset with an application to maternity leave uptake

Legislation over the past two decades enhanced the availability and quantity of statutory maternity leave in the United Kingdom. In high-skilled sectors, many employers top up this maternity leave in an effort to retain and develop the careers of women. As leave provision became more generous, debates emerged as to the role, if any, these enhanced benefits have in retaining women in high status occupation and facilitating their career growth. Further, individual situations and employment status may prevent women from taking advantage of enhanced benefits. This paper presents findings from a comprehensive survey of thousands of women in the UK Higher Education sector and documents how the lives of academic mothers changed over the past quarter century. Contract status and the partner’s participation in parenting has significant effects on the types of maternity leave taken. We reflect on these findings and discuss future research in the area of labour market equity and productivity the availability of this comprehensive quantitative survey of academic women can facilitate

A Variational Fock-Space Treatment of Quarkonium

The variational method and the Hamiltonian formalism of QCD are used to derive relativistic, momentum space integral equations for a quark-antiquark system with an arbitrary number of gluons present. As a first step, the resulting infinite chain of coupled equations is solved in the nonrelativistic limit by an approximate decoupling method. Comparison with experiment allows us to fix the quark mass and coupling constant, allowing for the calculation of the spectra of massive systems such as charmonium and bottomonium. Studying the results with and without the nonAbelian terms, we find that the presence of the nonAbelian factors yields better agreement with the experimental spectra.Comment: TEX, no figure

Influence of organic and mineral amendments on microbial soil properties and processes

Microbial diversity in soils is considered important for maintaining sustainability of agricultural production systems. However, the links between microbial diversity and ecosystem processes are not well understood. This study was designed to gain better understanding of the effects of short-term management practices on the microbial community and how changes in the microbial community affect key soil processes. The effects of different forms of nitrogen (N) on soil biology and N dynamics was determined in two soils with organic and conventional management histories that varied in soil microbial properties but had the same fertility. The soils were amended with equal amounts of N (100 kg ha⁻¹) in organic (lupin, Lupinus angustifolius L.) and mineral form (urea), respectively. Over a 91-day period, microbial biomass C and N, dehydrogenase enzyme activity, community structure of pseudomondas (sensu stricto), actinomycetes and α proteobacteria (by denaturing gradient gel electrophoresis (DGGE) following PCR amplification of 16S rDNA fragments) and N mineralisation were measured. Lupin amendment resulted in a two- to five-fold increase in microbial biomass and enzyme activity, while these parameters did not differ significantly between the urea and control treatments. The PCR–DGGE analysis showed that the addition of mineral and organic compounds had an influence on the microbial community composition in the short term (up to 10 days) but the effects were not sustained over the 91-day incubation period. Microbial community structure was strongly influenced by the presence or lack of substrate, while the type of amendment (organic or mineral) had an effect on microbial biomass size and activity. These findings show that the addition of green manures improved soil biology by increasing microbial biomass and activity irrespective of management history, that no direct relationship existed among microbial structure, enzyme activity and N mineralisation, and that microbial community structure (by PCR–DGGE) was more strongly influenced by inherent soil and environmental factors than by short-term management practices

Toward Open Science at the European Scale: Geospatial Semantic Array Programming for Integrated Environmental Modelling

[Excerpt] Interfacing science and policy raises challenging issues when large spatial-scale (regional, continental, global) environmental problems need transdisciplinary integration within a context of modelling complexity and multiple sources of uncertainty. This is characteristic of science-based support for environmental policy at European scale, and key aspects have also long been investigated by European Commission transnational research. Approaches (either of computational science or of policy-making) suitable at a given domain-specific scale may not be appropriate for wide-scale transdisciplinary modelling for environment (WSTMe) and corresponding policy-making. In WSTMe, the characteristic heterogeneity of available spatial information and complexity of the required data-transformation modelling (D-TM) appeal for a paradigm shift in how computational science supports such peculiarly extensive integration processes. In particular, emerging wide-scale integration requirements of typical currently available domain-specific modelling strategies may include increased robustness and scalability along with enhanced transparency and reproducibility. This challenging shift toward open data and reproducible research (open science) is also strongly suggested by the potential - sometimes neglected - huge impact of cascading effects of errors within the impressively growing interconnection among domain-specific computational models and frameworks. Concise array-based mathematical formulation and implementation (with array programming tools) have proved helpful in supporting and mitigating the complexity of WSTMe when complemented with generalized modularization and terse array-oriented semantic constraints. This defines the paradigm of Semantic Array Programming (SemAP) where semantic transparency also implies free software use (although black-boxes - e.g. legacy code - might easily be semantically interfaced). A new approach for WSTMe has emerged by formalizing unorganized best practices and experience-driven informal patterns. The approach introduces a lightweight (non-intrusive) integration of SemAP and geospatial tools - called Geospatial Semantic Array Programming (GeoSemAP). GeoSemAP exploits the joint semantics provided by SemAP and geospatial tools to split a complex D-TM into logical blocks which are easier to check by means of mathematical array-based and geospatial constraints. Those constraints take the form of precondition, invariant and postcondition semantic checks. This way, even complex WSTMe may be described as the composition of simpler GeoSemAP blocks. GeoSemAP allows intermediate data and information layers to be more easily and formally semantically described so as to increase fault-tolerance, transparency and reproducibility of WSTMe. This might also help to better communicate part of the policy-relevant knowledge, often diffcult to transfer from technical WSTMe to the science-policy interface. [...