Recognizing pedogenic features in Paleogene sandstones and silcretes in Belgium: a key-feature for paleoenvironmental and sourcing material studies

International audienceA few sandstones occurring in Belgium, especially those from Paleogene strata, share many common features with pedogenic and groundwater silcretes documented in the Paris Basin in France, in South Africa and in Australia (e.g. Thiry, 1999; Summerfield, 1983; Webb & Golding, 1998,). Here we present a review of the criteria that may be used to assess the pedogenic (or "groundwater") origin for sandstones and silcretes. At field scale, pedogenic features in silcrete often consist in the development of vertical (columnar) or nodular structures and/or layers (horizons) due to vetical percolation (illuviation) and transformation of materials in the profile porosity and cracks. Groundwater silcrete often exhibit a typical mammilated surface (e.g. Nash & Ullyot, 2007). Root and rootlet casts, sometimes with silicified root or wood material, also indicate that the rock evolved at the surface or near-surface. At microscopic scale, illuviation of silt and clays in the vadose or water-table environment results in the formation of a series of finely-laminated coatings and infillings. These pedofeatures consist in "typic", "crescent", "capping", "pendent", "micropan" and "crust" coatings (Bullock et al., 1985). Irregular rounded structures or "glaebules" also develop as well as micro-columnar or prismatic textures. Many of them have been observed in pedogenic silcretes around the world (e.g. Thiry, 1999) but also in Paleogene silcrete in Belgium (e.g. Veldman et al., in review). Of particular importance is the concentration of fine-grained titanium-oxides in pedogenic silcrete. These Ti-oxides most probably originated from the weathering of clay material and were concentrated via the same pedogenic processes which concentrated silica in the silcrete profile (Thiry, 1997). In sandstones with a pure sand matrix, where no or few fine-grained material is available for illuviation, assessing the pedogenic origin for the silicification is much more difficult based solely on microtextural observations. New perspectives may arise from trace-element analysis in the quartz cement overgrowing the grains. For example, combining cathodoluminescence imaging (CL) and electron microprobe analysis (EPMA) allowed the detec on of abnormally-high concentration of Al and K in the quartz cement relative to the quartz grains in the Grandglise Thanetian sandstone in the Mons Basin (figure). This suggests that first the weathering of glauconite, which is actually observed here, is the likely source for silica and secondly, the evidence for aluminum migration would indicate strongly acidic conditions in the pore fluids

RÉGIMES DE RETRAITE, INÉGALITÉS DE REVENU ET REDISTRIBUTION AU MAGHREB

Les systèmes de retraite du Maghreb ont des effets contradictoires sur la répartition des revenus des assurés sociaux. Ils ont tendance à amplifier l’écart entre salariés du public et du privé, mais à l’inverse à resserrer l’éven-tail des revenus à l’intérieur de chaque régime. Ils opèrent une redistribution horizontale au profit des familles par les pensions au profit des survivants. Entre générations, les vieux retraités sont défavorisés par rapport aux jeunes retraités et des dispositifs temporaires de retraite anticipée créent des inéquités. L’inégalité la plus forte oppose les assurés aux non assurés dans la mesure où les systèmes de retraite ne couvrent qu’une fraction minoritaire de la population âgée. Abstract - The North African pension systems have contradictory effects on the income distribution of insured persons. These systems tend to increase the gap between public and private sector employees. Conversely, they tend to narrow the income range within each system. They lead to horizontal redistribution to the benefit of families thanks to pensions paid to survivor. Among pensioners, the older pensioners are at a disadvantage compared with the younger. Moreover, temporary plans of early retirement increase those inequalities. The strongest inequality however is between insured and non-insured persons due to the fact that pension systems cover only a small proportion of the old population.SYSTÈMES DE RETRAITE, INÉGALITÉS DE REVENU, MAGHREB

Is the Relationship Between Major Depressive Disorder and Self-Reported Alcohol Use Disorder an Artificial One?

Aims: Many studies have suggested a close relationship between alcohol use disorder (AUD) and major depressive disorder (MDD). This study aimed to test whether the relationship between self-reported AUD and MDD was artificially strengthened by the diagnosis of MDD. This association was tested comparing relationships between alcohol use and AUD for depressive people and non-depressive people. Methods: As part of the Cohort Study on Substance Use Risk Factors, 4352 male Swiss alcohol users in their early twenties answered questions concerning their alcohol use, AUD and MDD at two time points. Generalized linear models for cross-sectional and longitudinal associations were calculated. Results: For cross-sectional associations, depressive participants reported a higher number of AUD symptoms (β = 0.743, P Conclusion: MDD thus appeared to be a confounding variable in the relationship between alcohol use and AUD, and self-reported measures of AUD seemed to be overestimated by depressive people. This result brings into question the accuracy of self-reported measures of substance use disorders. Furthermore, it adds to the emerging debate about the usefulness of substance use disorder as a concept, when heavy substance use itself appears to be a sensitive and reliable indicator

Measuring bath properties using the STARprobe TM

Abstract Since the beginning of 2012, STAS is the world distributor of the STARprobe TM developed by Alcoa During those campaigns, the STARprobe TM bath properties measurements have been compared with standard bath properties measurements regularly carried out in those smelters operated by different aluminium producers. Those independent comparative measurements all confirmed the capacity of the STARprobe TM to instantaneously and accurately measure Superheat, Temperature, Alumina concentration and bath Ratio for cell control purposes

Investigating the incidence and magnitude of heterotopic ossification with and without joints involvement in patients with a limb fracture and mild traumatic brain injury

Objectives: This study seeks to evaluate the incidence rate of heterotopic ossification (HO) formation in patients afflicted by an isolated limb fracture (ILF) and a concomitant mild traumatic brain injury (mTBI). Methods: The current study is an observational study including ILF patients with or without a concomitant mTBI recruited from an orthopedic clinic of a Level 1 Trauma Hospital. Patients were diagnosed with a mTBI according to the American Congress of Rehabilitation Medicine (ACRM) criteria. Radiographs taken on average 3 months post-trauma were analyzed separately by two distinct specialists for the presence of HO proximally to the fracture site (joints or extra joints). Both raters referred to Brooker's and Della's Valle's classification to establish signs of HO. First, analyses were conducted for the full sample. Secondly, a matched cohort was used in order to control for specific factors, namely age, sex, type of injury, and time elapsed between the accident and the analyzed radiograph. Results: The full sample included a total of 183 patients with an ILF (94 females; 47.5 years old), of which 50 had a concomitant mTBI and 133 without. Radiographic evidence of HO was significantly higher in patients with an ILF and a mTBI compared to ILF patients (X2 = 6.50; p = 0.01). The matched cohort consisted of 94 participants (i.e.; 47 patients from the ILF + mTBI group and 47 patients from the ILF group). Again, ILF + mTBI patients presented significantly higher rates of HO signs in comparison to ILF patients (X2 = 3.69; p = 0.04). Presence of HO was associated with prolonged delays to return to work (RTW) only in ILF + mTBI patients (F = 4.055; p = 0.05) but not in ILF patients (F = 0.823; p = 0.37). Conclusions: Study findings suggest that rates of HO are significantly higher proximally to fracture sites when ILF patients sustain a concomitant mTBI, even after controlling for factors known to influence HO. Moreover, results show that HO is associated with a prolonged RTW only in ILF patients with a concomitant mTBI but not in ILFonly patients. The impact of mTBI on HO formation warrants further attention to detect early signs of HO, to identify shared physiopathological mechanisms and, ultimately, to design targeted therapies

: Maurocalcine transduction into cells

International audienceMaurocalcine (MCa) is a 33-amino-acid residue peptide toxin isolated from the scorpion Scorpio maurus palmatus. External application of MCa to cultured myotubes is known to produce Ca2+ release from intracellular stores. MCa binds directly to the skeletal muscle isoform of the ryanodine receptor, an intracellular channel target of the endoplasmic reticulum, and induces long lasting channel openings in a mode of smaller conductance. Here we investigated the way MCa proceeds to cross biological membranes to reach its target. A biotinylated derivative of MCa was produced (MCa(b)) and complexed with a fluorescent indicator (streptavidine-cyanine 3) to follow the cell penetration of the toxin. The toxin complex efficiently penetrated into various cell types without requiring metabolic energy (low temperature) or implicating an endocytosis mechanism. MCa appeared to share the same features as the so-called cell-penetrating peptides. Our results provide evidence that MCa has the ability to act as a molecular carrier and to cross cell membranes in a rapid manner (1-2 min), making this toxin the first demonstrated example of a scorpion toxin that translocates into cells

Aerodynamic and Aeroacoustic Study of Low Reynolds Number Rotors: Influence of Pitch Angle, Airfoil Camber and Thickness

With the increase in the use of micro air vehicles (MAVs), the issue of noise pollution is becoming critical in both military and civilian fields. The main noise component in quadcopter MAVs is generated by the rotors and their interactions with the whole body. Here, a Non-Linear Vortex Lattice/Particle Method (NVLM), coupled with the Farassat formulation-1A of the Ffowcs-Williams and Hawkings (FW-H) acoustic analogy, is used to characterize the influence of the blade pitch and the airfoil shape on the tonal noise and the aerodynamic performance of low Reynolds number rotors typical of MAVs. The validation of both NVLM and FW-H codes is adressed with test cases from the literature and experiments on a 25cm diameter NACA0012 constant-pitch rotor in hovering conditions. The tonal noise of this MAV rotor is then studied in details. Finally, a parametric study of rotor pitch angle and of airfoil camber and thickness is performed, providing guidelines for the design of small rotors with low acoustic footprint and optimal aerodynamic performance