Analysis of chlorinated, sulfochlorinated and sulfonamide derivatives of n-tetradecane by gas chromatography/mass spectrometry

The photosulfochlorination of n-tetradecane by sulfuryl chloride leads to a reaction mixture containing unreacted n-tetradecane, chloro n-tetradecanes and n-tetradecanesulfonyl chlorides. Direct and simultaneousGCanalysis of the mixture of the sulfochlorinated and chlorinated isomers is followed by mass spectrometry identification of all the components either by electron impact (EI-MS) and by negative and positive chemical ionisation (NCI-MS and PCI-MS). With the goal of performing an accurate quantitative GC analysis, and as n-tetradecanesulfonyl chlorides prone to degrade partially into the corresponding chlorides, the former are converted to N,N-diethylsufonamides, more stable thermally, and then analysed by GC/EI-MS and GC/PCI-MS. The chloro n-tetradecanes, sulfonylchlorides and sulfonamides spectra present strong similarities. However, some differences between terminal and internal isomers are noticed and the peculiar behaviour of sulfonamides is emphasized

Modeling Biased Tracers at the Field Level

In this paper we test the perturbative halo bias model at the field level. The advantage of this approach is that any analysis can be done without sample variance if the same initial conditions are used in simulations and perturbation theory calculations. We write the bias expansion in terms of modified bias operators in Eulerian space, designed such that the large bulk flows are automatically resummed and not treated perturbatively. Using these operators, the bias model accurately matches the Eulerian density of halos in N-body simulations. The mean-square model error is close to the Poisson shot noise for a wide range of halo masses and it is rather scale-independent, with scale-dependent corrections becoming relevant at the nonlinear scale. In contrast, for linear bias the mean-square model error can be higher than the Poisson prediction by factors of up to a few on large scales, and it becomes scale dependent already in the linear regime. We show that by weighting simulated halos by their mass, the mean-square error of the model can be further reduced by up to an order of magnitude, or by a factor of two when including $60\%$ mass scatter. We also test the Standard Eulerian bias model using the nonlinear matter field measured from simulations and show that it leads to a larger and more scale-dependent model error than the bias expansion based on perturbation theory. These results may be of particular relevance for cosmological inference methods that use a likelihood of the biased tracer at the field level, or for initial condition and BAO reconstruction that requires a precise estimate of the large-scale potential from the biased tracer density.Comment: 61 pages, 27 figures. Minor edits and added references to match published versio

Investigating the role of parietal and prefrontal cortices in spatial working memory using tDCS

Question – Working memory involves the temporary storage, processing, and manipulation of information. Previous studies have suggested that the posterior parietal cortex (PPC), and dorsolateral prefrontal cortex (DLPFC) are involved in spatial working memory, and spatial and object working memory, respectively. The aim of the present pilot study was to investigate whether modulation of the activity of the left PPC and the left DLPFC changes spatial, and object working memory performance. Transcranial direct current stimulation (tDCS) was used for this purpose. Based on past literature we expected to see improvement of both spatial and object working memory after tDCS of the left DLPFC as well as improvement of spatial working memory after tDCS of the left PPC. Methods – Participants (n = 12) attended three experimental sessions with different stimulation conditions. Fifteen minutes of 1.5 mA anodal tDCS was applied over either the left PPC, left DLPFC or occipital lobe as control condition, beginning five minutes before the task. Participants were required to perform a 2-back spatial and object working memory task; i.e., they were required to pay attention to both objects and their location. Abstract objects were presented on either of an eight locations placed on a virtual circle around the centre of the screen. In addition to a 2-back object working memory task, occasionally participants were asked to indicate the location of the object they saw two screens previously. Performance in three different conditions was measured for analysis: (1) 2-back working memory task for the cases in which both cue and target objects were presented in the same location (OWM-same), (2) in different location (OWM-different) and (3) spatial working memory (SWM). Results – Preliminary results showed that performance in the OWM-different condition was lower than OWM-same. There, however, was no significant different between different stimulation conditions. Conclusions – These results suggest that anodal tDCS to the left PPC and left DLPFC might not be able to modulate spatial, and object working memory performance. Further studies are needed to investigate the differential role(s) of the DLPFC and PPC in spatial and working memory

Les profits " excessifs " des commerçants de fruits et légumes en Algérie : réalité ou préjugé infondé ? Le cas de la tomate primeur à Biskra

Dans les pays en développement, les agriculteurs dépendent, pour la commercialisation de leurs produits, d'un réseau complexe d'intermédiaires, souvent accusés de réaliser des profits excessifs. C'est le cas en Algérie, où ce discours est relayé par les agriculteurs et les consommateurs. Est-ce une réalité ou un préjugé infondé ? Cette étude se focalise sur la filière tomate primeur d'El Ghrous (wilaya de Biskra, dans le Sahara algérien), dont la production a connu un développement fulgurant ces 20 dernières années. Dans un premier temps, les facteurs, endogènes et exogènes, déterminant la formation des prix sont identifiés. Dans un second temps, la répartition de la valeur ajoutée le long de la filière est analysée à travers le calcul du délai de récupération des fonds investis et une comparaison des taux de marge des acteurs. Les résultats montrent que, pour cette filière, les intermédiaires ne réalisent pas de profits excessifs au détriment des agriculteurs. Le marché de gros d'El Ghrous est efficace, ce qui constitue un atout majeur pour le développement des cultures maraîchères dans la région. (Résumé d'auteur

Skin involvement in early diffuse cutaneous systemic sclerosis: an unmet clinical need

Diffuse cutaneous systemic sclerosis (dcSSc) is associated with high mortality resulting from early internal-organ involvement. Clinicians therefore tend to focus on early diagnosis and treatment of potentially life-threatening cardiorespiratory and renal disease. However, the rapidly progressive painful, itchy skin tightening that characterizes dcSSc is the symptom that has the greatest effect on patients' quality of life, and there is currently no effective disease-modifying treatment for it. Considerable advances have been made in predicting the extent and rate of skin-disease progression (which vary between patients), including the development of techniques such as molecular analysis of skin biopsy samples. Risk stratification for progressive skin disease is especially relevant now that haematopoietic stem-cell transplantation is a treatment option, because stratification will inform the balance of risk versus benefit for each patient. Measurement of skin disease is a major challenge. Results from clinical trials have highlighted limitations of the modified Rodnan skin score (the current gold standard). Alternative patient-reported and other potential outcome measures have been and are being developed. Patients with early dcSSc should be referred to specialist centres to ensure best-practice management, including the management of their skin disease, and to maximize opportunities for inclusion in clinical trials

Motion study of the hip joint in extreme postures

Many causes can be at the origin of hip osteoarthritis (e.g., cam/pincer impingements), but the exact pathogenesis for idiopathic osteoarthritis has not yet been clearly delineated. The aim of the present work is to analyze the consequences of repetitive extreme hip motion on the labrum cartilage. Our hypothesis is that extreme movements can induce excessive labral deformations and lead to early arthritis. To verify this hypothesis, an optical motion capture system is used to estimate the kinematics of patient-specific hip joint, while soft tissue artifacts are reduced with an effective correction method. Subsequently, a physical simulation system is used during motion to compute accurate labral deformations and to assess the global pressure of the labrum, as well as any local pressure excess that may be physiologically damageable. Results show that peak contact pressures occur at extreme hip flexion/abduction and that the pressure distribution corresponds with radiologically observed damage zones in the labru