Search results for "Complex."

Effect of sulfur dioxide on mucociliary activity and ciliary beat frequency in guinea pig trachea

1994

The effects of 30 min exposure to sulfur dioxide on mucociliary activity (MCA) and ciliary beat frequency (CBF) were studied in 31 guinea pig tracheas. MCA was measured by recording the light reflected from ciliated mucous membranes using an infrared bar code reader. CBF of single ciliated cells obtained by brushing was measured with phase-contrast microscopy. Each tracheal sample was exposed to SO2 at concentrations ranging from 2.5 to 12.5 ppm, or to air for control purposes. MCA and CBF were measured before and immediately after gas exposure. A reduction in mean MCA of 63% (P = 0.0007) and statistically insignificant changes in CBF (P > 0.05) were recorded at concentrations of 2.5 PPM SO…

Dynamic Gaussian Graphical Models for Modelling Genomic Networks

2014

After sequencing the entire DNA for various organisms, the challenge has become understanding the functional interrelatedness of the genome. Only by understanding the pathways for various complex diseases can we begin to make sense of any type of treatment. Unfortunately, decyphering the genomic network structure is an enormous task. Even with a small number of genes the number of possible networks is very large. This problem becomes even more difficult, when we consider dynamical networks. We consider the problem of estimating a sparse dynamic Gaussian graphical model with \(L_1\) penalized maximum likelihood of structured precision matrix. The structure can consist of specific time dynami…

On the regeneration of thermally regenerative ammonia batteries

2018

In the past few years, thermally regenerative ammonia battery (TRAB) has been proposed as an effective tool to recover waste heat at temperatures below 130 °C. Most of the literature available is devoted to the power production step, with less attention being given to the regeneration step (e.g. the removal of ammonia from the anolyte). In this paper, the TRAB is analyzed with particular attention to the regeneration step and to the study of various generation of energy-regeneration cycles. It was shown that approximately 90 °C is necessary for the regeneration step due to the fact that ammonia is present in the anolyte mainly as a complex. Various cycles were performed with success, demons…

X-Ray crystallographic and computational study on uranyl-salophen complexes bearing nitro groups.

2017

In the solid state, salophen–UO2 complexes bearing one, two, or three NO2 groups lack the pronounced ligand curvature that represents a structural hallmark for this class of compounds. A detailed structural study based on single-crystal X-ray crystallography and computational methods, comprising molecular dynamics, gas-phase Hartree Fock, and DFT calculations, was carried out to investigate the coordination properties of the uranyl cation.

Matching beer with food : pairing principles, underlying mechanisms and a focus on aromatic similarity

2018

Pairing between beer and dishes emerges as a new trend in France. Beer promoters or gastronomy professionals need to offer high-quality advices in terms of beer and food pairing to their customers. Within this context, the objective of the research was to identify pairing principles and to better understand the underlying perceptual mechanisms. Determinants of food and beverage pairing were first analysed from experts’ discourses. Results showed that food and beverage pairings are governed by perceptual, conceptual and affective features, related to physio-chemical, perceptual and cognitive processes. Experts often mentioned “Aromatic Similarity” as one of the main pairing principles. This …

An approach for influence estimatation in complex networks : application to the social network Twitter

2019

Influence in complex networks and in particular Twitter has become recently a hot research topic. Detecting most influential users leads to reach a large-scale information diffusion area at low cost, something very useful in marketing or political campaigns. In this thesis, we propose a new approach that considers the several relations between users in order to assess influence in complex networks such as Twitter. We model Twitter as a multiplex heterogeneous network where users, tweets and objects are represented by nodes, and links model the different relations between them (e.g., retweets, mentions, and replies).The multiplex PageRank is applied to data from two datasets in the political…

Visual category representations in the infant brain

2021

SUMMARYVisual categorization is a human core cognitive capacity1,2that depends on the development of visual category representations in the infant brain3–7. However, the exact nature of infant visual category representations and their relationship to the corresponding adult form remains unknown8. Our results clarify the nature of visual category representations from electroencephalography (EEG) data in 6- to 8-month-old infants and their developmental trajectory towards adult maturity in the key characteristics of temporal dynamics2,9, representational format10–12, and spectral properties13,14. Temporal dynamics change from slowly emerging, developing representations in infants to quickly e…

Digital Resilience to Normal Accidents in High-Reliability Organizations

2021

Digital technologies play a dual role on organizational resilience. On one side, digital systems introduce new technological risks. On the other side, digital systems increase the performances in response to hazardous accidents. Normal Accident Theory (NAT) and High-Reliability Organization (HRO) provide useful ground to explain the dynamics of digital resilience. However, the two theories have been either used as alternatives or with one theory dominating the other. We posit that to fully understand digital resilience we need to integrate NAT and HRO concepts instead of using them in isolation. We conduct a bibliometric analysis to identify major themes and application domains characterizi…

Attracteurs et bifurcations en dynamique holomorphe

2019

Development of multivariate and network models for the analysis of Big Data: applications in economics, insurance, and social sciences

2020

In questa tesi sviluppo metodi statistici multivariati e di rete per lo studio di sistemi complessi. In particolare, focalizzo la mia analisi sullo studio di reti complesse bipartite e le loro applicazioni a (i) l'economia, per capire l'effetto di contagio tra istituti finanziari e stati sovrani, (ii) la sorveglianza nelle assicurazioni, per individuare comportamenti fraudolenti, e (iii) le scienze sociali, per studiare l'effetto delle politiche del REF sulle eccellenze nella ricerca delle università in UK. In this thesis I develop multivariate statistical and network methods for the study of complex systems. In particular, I focus my analysis on the study of bipartite complex networks and …