University of Mons

About: University of Mons is a education organization based out in Mons, Belgium. It is known for research contribution in the topics: Large Hadron Collider & Standard Model. The organization has 3073 authors who have published 9465 publications receiving 294776 citations.

The Deterministic plus Stochastic Model of the Residual Signal and its Applications

Abstract: The modeling of speech production often relies on a source-filter approach. Although methods parameterizing the filter have nowadays reached a certain maturity, there is still a lot to be gained for several speech processing applications in finding an appropriate excitation model. This manuscript presents a Deterministic plus Stochastic Model (DSM) of the residual signal. The DSM consists of two contributions acting in two distinct spectral bands delimited by a maximum voiced frequency. Both components are extracted from an analysis performed on a speaker-dependent dataset of pitch-synchronous residual frames. The deterministic part models the low-frequency contents and arises from an orthonormal decomposition of these frames. As for the stochastic component, it is a high-frequency noise modulated both in time and frequency. Some interesting phonetic and computational properties of the DSM are also highlighted. The applicability of the DSM in two fields of speech processing is then studied. First, it is shown that incorporating the DSM vocoder in HMM-based speech synthesis enhances the delivered quality. The proposed approach turns out to significantly outperform the traditional pulse excitation and provides a quality equivalent to STRAIGHT. In a second application, the potential of glottal signatures derived from the proposed DSM is investigated for speaker identification purpose. Interestingly, these signatures are shown to lead to better recognition rates than other glottal-based methods.

A prospective study of the association between endogenous hormones and depressive symptoms in postmenopausal women.

Abstract: Objective Across a woman's lifetime, variations in hormone levels are known to influence mood and well-being. Whether absolute or changes in hormone levels over time are associated with depression among postmenopausal women remains unclear. Methods The Melbourne Women's Midlife Health Project is a longitudinal population-based study of women who were followed through the menopausal transition. This analysis is based on data collected from 138 postmenopausal women in years 11 and 13 of the study, who were assessed for the presence of depressive symptoms using the Center for Epidemiological Studies Depression Scale. Logistic regression models were developed to determine whether absolute or changes in hormone levels were associated with depression. Results No significant associations were found between depressive symptoms and the absolute levels of sex hormone-binding globulin, testosterone, free androgen index, estradiol, free estradiol, or follicle-stimulating hormone (FSH). On the other hand, women with a decline in total serum estradiol over the 2-year period had a more than threefold increased risk of depressive symptoms (odds ratio, 3.5; 95% CI, 1.2-9.9). A large increase in FSH levels over this period was also associated with depressive symptoms (odds ratio, 2.6; 95% CI, 1.0-6.7). These associations remained even after adjustment for initial depression score, as well as a range of potential confounding factors. Conclusions Changes in estradiol and, to a lesser extent, in FSH levels are associated with an increased risk of depressive symptoms in postmenopausal women. These results further support a role for fluctuating rather than absolute hormone levels in depression in later life.

Guanosine‐based Hydrogen‐bonded Scaffolds: Controlling the Assembly of Oligothiophenes

Abstract: The controlled and preprogrammed self-assembly of p-conjugated rodand disc-like oligomers into ordered and anisotropic architectures is an important goal in view of the tailoring of their physico-chemical properties and, ultimately, for their application in molecularand nanoelectronics. Among weak interactions, p-stacking has been the first to be employed to drive the self-assembly of conjugated (macro)molecular systems into well-defined nanoscale assemblies that feature a high degree of order at the supramolecular level. Later, other types of weak yet directional non-covalent interactions, in particular H-bonds, have been used to form both monoand multicomponent p-conjugated architectures, and their application in the fabrication of optoelectronic device prototypes such as photovoltaic diodes and ambipolar transistors has been attempted. Lipophilic guanosines are very versatile building blocks: depending on the experimental conditions they can undergo different self-assembly pathways, leading to the formation of either H-bonded ribbons or quartet-based columnar structures (Fig. 1). Given the possibility to functionalize the guanosines in the side-chains they appear as ideal building blocks for the fabrication of complex architectures with a controlled high rigidity, thus paving the way towards their future use for

Dynamic nature of excited states of donor–acceptor TADF materials for OLEDs: how theory can reveal structure–property relationships

Abstract: Spin statistics greatly limits the efficiency of OLEDs, which might be largely improved upon conversion of triplet into singlet-excited (and thus light-emitting) states via a Thermally Activated Delayed Fluorescence (TADF) process. We theoretically investigate here the combination of some real-life donor (D) and acceptor (A) moieties with the connectivity D–A and D–A–D. We selected phenoxazine (PXZ) and phenylthiazine (PTZ) as electron-donating groups, and 2,5-diphenyl-1,3,4-oxadiazole (OXD), 3,4,5-triphenyl-4H-1,2,4-triazole (TAZ), and 2,5-diphenyl-1,3,4-thiadiazole (TDZ) as their electron-accepting partners. The systematic Tamm–Dancoff Approximation-Density Functional Theory calculations performed allowed us to calculate accurately not only the energy levels of low-lying singlet and triplet-excited states, but also to characterize their Charge-Transfer (CT) or Locally Excited (LE) nature, since the energy difference and the coupling between the 3CT, 3LE, and 1CT states become key to understanding the molecular mechanism involved in this process. We have also studied the role played by the conformational landscape, arising from the thermally accessible range of D–A(–D) torsion angles, in the singlet–triplet energy gap as well as its influence on oscillator strengths. Overall, we rationalize the origin of the higher efficiencies found in real devices for D–A–D molecules, disclosing the underlying structure–property relationships and thus anticipating successful design strategies.