Ostracods, rock facies and magnetic susceptibility of the Hanonet Formation / Trois-Fontaines Formation boundary interval (Early Givetian) at the Mont d’Haurs (Givet, France)

Approximately 870 carapaces, valves and fragments of ostracods were extracted from 26 samples collected in the Hanonet Formation (= Fm) and Trois-Fontaines Fm in a section located along the southwestern rampart of the historically entrenched military camp at the Mont d’Haurs (Givet, France). Forty-eight species belonging to the Eifelian Mega-Assemblage have been identified and three new are proposed: Coryellina? audiarti nov. sp., Cavellina haursensis nov. sp. and Parabolbinella coeni nov. sp. The ostracod assemblages are generally indicative of shallow marine well-oxygenated environments, except at the base of the Trois-Fontaines Fm where ostracods indicative of semi-restricted and even of lagoonal water conditions are reported.The sedimentary record represents a transition from mixed siliciclastic-carbonate open-marine ramp system to restricted carbonate platform with deposition in low-energy peritidal and lagoonal settings frequently affected by subaerial exposition. A general trend follows a shallowing-upward and a relative sea-level decrease from the Hanonet Fm toward the Trois-Fontaines Fm.High-energy characterized the ramp setting and destroyed most of the stromatoporoid and coral buildups, which occur as floatstone and rudstone accumulations forming a thick biostrome. Girvanella and issinellid shoals developed also in this high-energy environment. The low-field magnetic susceptibility (=MS) log plotted against the lithological column reveals four magnetic sequences. The MS log and microfacies are moderately correlated mainly due to the evolution of sedimentary environments from a ramp to a platform. The MS values of the Trois-Fontaines Fm are very low in the biostromal unit whereas restricted lagoonal facies are characterized by the highest values of MS. A high-resolution stratigraphic correlative pattern is proposed here between the Mont d’Haurs section and the 40 km distant Baileux section despite the greater thickness. The MS signal is strongly controlled by minerals of ferromagnetic characteristics with a minor contribution of paramagnetic phases. The lagoonal sediments of the Trois-Fontaines Fm are characterized also by the highest values of normalized viscosity coefficient and a IRM loss. These results confirm the occurrence of a significantly high proportion of ultrafine magnetic grains which may be formed during diagenesis by chemical remanent magnetization processes.The list of the Givetian ostracods figured by Coen (1985) and recently lodged at the Department of Paleontology at the Royal Belgian Institute of Natural Sciences is reported in annex with new inventory numbers

Ostracods, rock facies and magnetic susceptibility of the Trois-Fontaines and Terres d’Haurs Formations (Early Givetian) in the Rancennes quarry at the Mont d’Haurs (Givet, France)

About 1,200 ostracods were extracted from 64 samples collected in the upper part of the Trois-Fontaines Formation (Fm) and in the base of the Terres d’Haurs Fm in the Rancennes quarry located along the western rampart of an historic entrenched military camp at the Mont d’Haurs (southern part of the Dinant Synclinorium, Ardennes Department, France). The ostracod richness and diversity are quite variable, and monospecificity prevails in numerous samples. Forty-nine ostracod species are recognised. In the Trois-Fontaines Fm, environments were lagoonal or semi-restricted, and the level containing numerous Leperditicopid ostracods (Herrmannina) indicative of (brackish?) lagoonal environments is 40 m thick. In the Terres d’Haurs Fm the environment was semi-restricted or more frequently shallow marine but the energy of the environment was apparently never very high. The level rich in Leperditicopida (Herrmannina) in the Trois-Fontaines Fm corresponds remarkably to the highest magnetic susceptibility (MS) value. The Rancennes microfacies point to a tidal flat system with various subenvironments such as restricted intertidal, supratidal and channel deposits. The system was bordered by subtidal open marine deposits where former reefal constructions have been destroyed. Frequent oscillations in this low-gradient shallow platform led to the exposure and modification of marginal ponds, floodplain environments or palustrine areas. No evidence of evaporitic environments or sabkha were encountered. The sedimentary system records the evolution of a shallow restricted carbonate platform (Trois-Fontaines Fm) to a carbonate ramp setting (Terres d’Haurs Fm). The evolution of the platfom to a ramp could be related to the cessation of the active role of a reefal barrier possibly as a response to synsedimentary tectonism and block faulting.The magnetic susceptibility curve established for the Rancennes quarry highlights 26 short-term magnetic evolutions that can be grouped into 10 major long-term magnetic sequences characterized by decreasing, increasing or stable magnetic susceptibility fluctuations. Magnetic susceptibility values range between 3.75 x 10-9 and 2.98 x 10-7 m³/kg. There is a general good correspondence between the microfacies and magnetic susceptibility curves, which are clearly mimetic at the smaller scale (i.e., 5th-order parasequences). The magnetic susceptibility curve could thus be interpreted as sea-level oscillations. A part of the magnetic minerals carrying the MS signal must have a detrital origin. Magnetization and coercivity ratios deduced from hysteresis loops indicate the presence of detrital coarse-grained multi-domain magnetite and authigenic mixtures of fine-grained superparamagnetic and single-domain magnetite. The MS signal of the Rancennes quarry seems to be controlled by the ferrimagnetic fraction (magnetite) with minor paramagnetic contribution (clay minerals and pyrite).The Rancennes quarry completes the stratotype of the Terres d’Haurs Fm because the section exposes the boundary with the Trois-Fontaines Fm unlike the previously proposed stratotype located on the south-eastern flank of the Mont d’Haurs entrenched camp

Multiwavelength Observations of the Hot DB Star PG 0112+104

We present a comprehensive multiwavelength analysis of the hot DB white dwarf PG 0112+104. Our analysis relies on newly-acquired FUSE observations, on medium-resolution FOS and GHRS data, on archival high-resolution GHRS observations, on optical spectrophotometry both in the blue and around Halpha, as well as on time-resolved photometry. From the optical data, we derive a self-consistent effective temperature of 31,300+-500 K, a surface gravity of log g = 7.8 +- 0.1 (M=0.52 Msun), and a hydrogen abundance of log N(H)/N(He) < -4.0. The FUSE spectra reveal the presence of CII and CIII lines that complement the previous detection of CII transitions with the GHRS. The improved carbon abundance in this hot object is log N(C)/N(He) = -6.15 +- 0.23. No photospheric features associated with other heavy elements are detected. We reconsider the role of PG 0112+104 in the definition of the blue edge of the V777 Her instability strip in light of our high-speed photometry, and contrast our results with those of previous observations carried out at the McDonald Observatory.Comment: 10 pages in emulateapj, 9 figures, accepted for publication in Ap

Ostracods and rock facies across the Givetian/Frasnian boundary interval in the Sourd d'Ave section at Ave-et-Auffe (Dinant Synclinorium, Ardenne, Belgium)

Ostracods from the Sourd d'Ave section have been collected in the Moulin Boreux and Fort Hulobiet Members (Fromelennes Fm., Givet Group) and in the Pont d'Avignon Member (Nismes Fm., Frasnes Group). Ostracods collected in the Fromelennes Fm. by Milhau (1983a) and in the Nismes Fm. by Casier (1987a) have been also reviewed. Forty-four ostracod species are identified in the Fromelennes Fm. and 25 in the Nismes Fm. They belong exclusively to the Eifelian Mega-Assemblage, and several assemblages indicative of restricted and shallow marine, sometimes agitated, environments are recognized in the Fromelennes Fm. The great rarity of ostracods in the upper part of this formation provides evidence for less favourable lagoonal conditions probably related to increasing aridity at the end of the Givetian. In the Frasnes Group, assemblages are exclusively open marine and indicative of increasing water depth. The majority of ostracod species recognized in the Givet Group are missing in the base of the Frasnes Group as a consequence of the Frasnes Event. A systematic list of ostracods identified in the Fromelennes Fm. at Sourd d'Ave is published as an annex. Systematic sampling has been carried out in order to establish the sedimentological evolution of the environments and to detail the Givetian-Frasnian (G/F) transition. This allowed recognition of 13 microfacies types that replicate the standard sequence of Preat & Mamet (1989) from open marine shallow subtidal to restricted supratidal near emersion. The Boreux Member and the Fort Hulobiet Member display restricted facies (Amphipora, spongiostromid and algal bafflestones and bindstones, loferites with desiccation lumps) with poorly fossiliferous beds interbedded with higher energy peloidal and sometimes oolitic grainstone facies. Laminite horizons, sometimes with small-sized lateral linked hemispheroid stromatolites are uncommon, and are associated with dolomicrites showing pseudomorphs of evaporite minerals. These evaporitic facies become common in the upper part of the Fort Hulobiet Member suggesting the palaeoclimate became more arid at the G/F transition. Metre-scale cyclicity is pervasive throughout the Givetian part of the section. The boundary between the Givet Group and the Frasnes Group is very distinctive in the field, and is characterized by a transition from restricted evaporative lagoonal facies to open marine interbedded marly shales and nodular limestones. The upper part of the Fort Hulobiet Member consists of interbedded biostromes (semi-restricted stromatoporoid boundstones) followed by Amphipora floatstones, then fossil-poor units and restricted supratidal laminites with well-developed fenestral fabrics. The Frasnian Pont d'Avignon Member contains a rich faunal assemblage (bryozoans brachiopods, molluscs, nautiloids, tentaculitids) suggesting an abrupt drowning from the marginal Givetian carbonate platform into a Frasnian distal ramp or deep basinal environment below or near storm wave base

A Comprehensive Spectroscopic Analysis of DB White Dwarfs

We present a detailed analysis of 108 helium-line (DB) white dwarfs based on model atmosphere fits to high signal-to-noise optical spectroscopy. We derive a mean mass of 0.67 Mo for our sample, with a dispersion of only 0.09 Mo. White dwarfs also showing hydrogen lines, the DBA stars, comprise 44% of our sample, and their mass distribution appears similar to that of DB stars. As in our previous investigation, we find no evidence for the existence of low-mass (M < 0.5 Mo) DB white dwarfs. We derive a luminosity function based on a subset of DB white dwarfs identified in the Palomar-Green survey. We show that 20% of all white dwarfs in the temperature range of interest are DB stars, although the fraction drops to half this value above Teff ~ 20,000 K. We also show that the persistence of DB stars with no hydrogen features at low temperatures is difficult to reconcile with a scenario involving accretion from the interstellar medium, often invoked to account for the observed hydrogen abundances in DBA stars. We present evidence for the existence of two different evolutionary channels that produce DB white dwarfs: the standard model where DA stars are transformed into DB stars through the convective dilution of a thin hydrogen layer, and a second channel where DB stars retain a helium-atmosphere throughout their evolution. We finally demonstrate that the instability strip of pulsating V777 Her white dwarfs contains no nonvariables, if the hydrogen content of these stars is properly accounted for.Comment: 74 pages including 30 figures, accepted for publication in the Astrophysical Journa

Design, Synthesis, Biological Evaluation, and Structure–Activity Relationships of Substituted Phenyl 4-(2-Oxoimidazolidin-1-yl)benzenesulfonates as New Tubulin Inhibitors Mimicking Combretastatin A-4

International audienc

Longitudinal study of childhood sleep trajectories and adolescent mental health problems

Abstract Study objective To investigate whether childhood sleep trajectories are associated with mental health symptoms such as social phobia, generalized anxiety, depression, attention deficit hyperactivity disorder (ADHD), conduct problems, and opposition at age 15. Methods A total of 2120 children took part in the Quebec Longitudinal Study of Child Development. Childhood sleep trajectories were computed from maternal reports at 2.5, 3.5, 4, 6, 8, 10, and/or 12 years. At age 15, 1446 adolescents filled out mental health and sleep questions. A path analysis model was assessed in the full sample. Results Four childhood nocturnal sleep duration trajectories were identified: (1) a short pattern (7.5%), (2) a short-increasing pattern (5.8%), (3) a 10 hours pattern (50.7%), and (4) an 11 hours pattern (36.0%). Three childhood sleep latency trajectories were found: (1) a short pattern (31.7%), (2) an intermediate pattern (59.9%), and (3) a long pattern (8.4%). Finally, two childhood wakefulness after sleep-onset trajectories were found: (1) a normative pattern (73.0%) and (2) a long pattern (27.0%). The path analysis model indicated that children following a long childhood sleep latency trajectory were more likely to experience symptoms of depression (β = 0.06, 95% CI: 0.01 to 0.12), ADHD (β = 0.07, 95% CI: 0.02 to 0.13), conduct problems (β = 0.05, 95% CI: 0.00 to 0.10) and opposition (β = 0.08, 95% CI: 0.02 to 0.13) at age 15. Conclusions This longitudinal study revealed that children presenting a long sleep latency throughout childhood are at greater risk of symptoms of depression, ADHD, conduct problems, and opposition in adolescence

Changes in functioning of mesolimbic incentive processing circuits during the premenstrual phase

The premenstrual phase of the menstrual cycle is associated with marked changes in normal and abnormal motivated behaviors. Animal studies suggest that such effects may result from actions of gonadal hormones on the mesolimbic dopamine (DA) system. We therefore investigated premenstrual changes in reward-related neural activity in terminal regions of the DA system in humans. Twenty-eight healthy young women underwent functional magnetic resonance imaging on 2 days during the menstrual cycle, once during the late follicular phase and once during the premenstrual phase, in counterbalanced order. Using a modified version of the monetary incentive delay task, we assessed responsiveness of the ventral striatum to reward anticipation. Our results show enhanced ventral striatal responses during the premenstrual as compared to the follicular phase. Moreover, this effect was most pronounced in women reporting more premenstrual symptoms. These findings provide support for the notion that changes in functioning of mesolimbic incentive processing circuits may underlie premenstrual changes in motivated behaviors. Notably, increases in reward-cue responsiveness have previously been associated with DA withdrawal states. Our findings therefore suggest that the sharp decline of gonadal hormone levels in the premenstrual phase may trigger a similar withdrawal-like state

N-(4-iodophenyl)-N′-(2-chloroethyl)urea as a microtubule disrupter: in vitro and in vivo profiling of antitumoral activity on CT-26 murine colon carcinoma cell line cultured and grafted to mice

The antitumoral profile of the microtubule disrupter N-(4-iodophenyl)-N′-(2-chloroethyl)urea (ICEU) was characterised in vitro and in vivo using the CT-26 colon carcinoma cell line, on the basis of the drug uptake by the cells, the modifications of cell cycle, and β-tubulin and lipid membrane profiles. N-(4-iodophenyl)-N′-(2-chloroethyl)urea exhibited a rapid and dose-dependent uptake by CT-26 cells suggesting its passive diffusion through the membranes. Intraperitoneally injected ICEU biodistributed into the grafted CT-26 tumour, resulting thus in a significant tumour growth inhibition (TGI). N-(4-iodophenyl)-N′-(2-chloroethyl)urea was also observed to accumulate within colon tissue. Tumour growth inhibition was associated with a slight increase in the number of G2 tetraploid tumour cells in vivo, whereas G2 blockage was more obvious in vitro. The phenotype of β-tubulin alkylation that was clearly demonstrated in vitro was undetectable in vivo. Nuclear magnetic resonance analysis showed that cells blocked in G2 phase underwent apoptosis, as confirmed by an increase in the methylene group resonance of mobile lipids, parallel to sub-G1 accumulation of the cells. In vivo, a decrease of the signals of both the phospholipid precursors and the products of membrane degradation occurred concomitantly with TGI. This multi-analysis established, at least partly, the ICEU activity profile, in vitro and in vivo, providing additional data in favour of ICEU as a tubulin-interacting drug accumulating within the intestinal tract. This may provide a starting point for researches for future efficacious tubulin-interacting drugs for the treatment of colorectal cancers