3,130 research outputs found
A fourth level of Frasnian carbonate mounds along the south side of the Dinant Synclinorium (Belgium)
An additional level of Frasnian mounds has been recognized in the La Boverie quarry at Rochefort and in four boreholes drilled in the Nord quarry at Frasnes, on the south side of the Dinant Synclinorium. It occurs between the Arche and Lion Members belonging respectively to the Moulin Liénaux and Grands Breux Formations, in the middle part of the stage. The new name of La Boverie Member is introduced at the top of the Moulin Liénaux Fm., for the deposits lying between the Arche and Bieumont Members; the latter is the basement of the Lion mound. The same succession has been observed in the sections of Moulin Bayot close to Vodelée, in the southeastern part of the Philippeville Anticlinorium. The La Boverie Member starts with rather deep bioclastic sediments, after the collapse of the carbonate factory at the top of the Arche mound. In the upper part of the lithostratigraphic unit, there is a thin buildup characterized by relatively shallow facies. The solitary rugose corals Macgeea boveriensis n. sp., M. socialis SOSHKINA, 1939 and Sinodisphyllum posterum (IVANIA, 1965) collected in the lower part of the La Boverie Member are described in detail whereas the revision of S. kielcense (ROZKOWSKA, 1979) occurring in the Bieumont Member is also provided
Sedimentologie et coraux du bioherme de marbre rouge Frasnien (F2j) de Tapoumont (Massif de Phillippeville, Belgique)
The sedimentological study of the Frasnian Tapoumont red marble bioherm (Philippeville antiform, Belgium, «F2j» based on rugose corals) enables recognition of twelve microfacies. They range from sponge spicule mudstones to crinoidal, coral rudstones. Water agitation and light supply normally control the bioherm growth, but three environments do not follow the rule. They are characterized by the abundance of microorganic mats, now in form of irregular plurimetric fenestrae. cemented by radiaxial calcite. They are more and more abundant towards the centre of the buildup. Four lateral microfacies are studied. The bioherm geometry is discussed, and a weak sedimentary slope is proposed
Application of multidisciplinary optimization methods to the design of a supersonic transport
An optimization design method is discussed. This method is based on integrating existing disciplinary analysis and sensitivity analysis techniques by means of generalized sensitivity equations. A generic design system implementing this method is described. The system is being used to design the configuration and internal structure of a supersonic transport wing for optimum performance. This problem combines the disciplines of linear aerodynamics, structures, and performance. Initial results which include the disciplines of aerodynamics and structures in a conventional minimum weight design under static aeroelastic constraints are presented
Sedimentologie paleoecologie et paleontologie des calcaires crinoidiques au voisinage de la limite couvinien-givetien a Wellin
The sedimentology of the Eifelian-Givetian boundary beds in the Wellin area indicates a transition from a siliciclastic-carbonate ramp to a gently sloping carbonate platform lacking a true reefal barrier. Prograding decametric sedimentary units form a littoral accretion megasequence. Corallian megafauna and algal microflora are highly diverse and abundant. Several communities are recognized in the ramp but they cannot be used for precise chronostratigraphic correlations.Comparison with other regions of the Dinant Synclinorium shows that the basin was already partitioned into blocks in Late Eifelian time. In Early Givetian several blocks of plurikilometric extension are identified. In this context, recognition of a new formation, provisionnally called "Formation X", between the Jemelle and Hanonet Formations, is significant.This local unit, some 120 meters thick, is composed of crinoidal and reefal limestones and indicates the existence of a sharply subsiding block in the Wellin area
Excess portal venous long-chain fatty acids induce syndrome X via HPA axis and sympathetic activation
We tested the hypothesis that excessive portal venous supply of long-chain fatty acids to the liver contributes to the development of insulin resistance via activation of the hypothalamus-pituitary-adrenal axis (HPA axis) and sympathetic system. Rats received an intraportal infusion of the long-chain fatty acid oleate (150 nmol/min, 24 h), the medium-chain fatty acid caprylate, or the solvent. Corticosterone (Cort) and norepinephrine (NE) were measured as indexes for HPA axis and sympathetic activity, respectively. Insulin sensitivity was assessed by means of an intravenous glucose tolerance test (IVGTT). Oleate infusion induced increases in plasma Cort (Δ = 13.5 ± 3.6 µg/dl; P < 0.05) and NE (Δ = 235 ± 76 ng/l; P < 0.05), whereas caprylate and solvent had no effect. The area under the insulin response curve to the IVGTT was larger in the oleate-treated group than in the caprylate and solvent groups (area = 220 ± 35 vs. 112 ± 13 and 106 ± 8, respectively, P < 0.05). The area under the glucose response curves was comparable [area = 121 ± 13 (oleate) vs. 135 ± 20 (caprylate) and 96 ± 11 (solvent)]. The results are consistent with the concept that increased portal free fatty acid is involved in the induction of visceral obesity-related insulin resistance via activation of the HPA axis and sympathetic system.
Superfast Vocal Muscles Control Song Production in Songbirds
Birdsong is a widely used model for vocal learning and human speech, which exhibits high temporal and acoustic diversity. Rapid acoustic modulations are thought to arise from the vocal organ, the syrinx, by passive interactions between the two independent sound generators or intrinsic nonlinear dynamics of sound generating structures. Additionally, direct neuromuscular control could produce such rapid and precisely timed acoustic features if syringeal muscles exhibit rare superfast muscle contractile kinetics. However, no direct evidence exists that avian vocal muscles can produce modulations at such high rates. Here, we show that 1) syringeal muscles are active in phase with sound modulations during song over 200 Hz, 2) direct stimulation of the muscles in situ produces sound modulations at the frequency observed during singing, and that 3) syringeal muscles produce mechanical work at the required frequencies and up to 250 Hz in vitro. The twitch kinematics of these so-called superfast muscles are the fastest measured in any vertebrate muscle. Superfast vocal muscles enable birds to directly control the generation of many observed rapid acoustic changes and to actuate the millisecond precision of neural activity into precise temporal vocal control. Furthermore, birds now join the list of vertebrate classes in which superfast muscle kinetics evolved independently for acoustic communication
- …