Révision de quelques Odontaspididae (Neoselachii: Lamniformes) du Paléocène et de l'Eocène du Bassin de la mer du Nord

The revision of some Odontaspididae species from the Paleocene and the Eocene of the North sea Basin has clarified the generic status of some of them and to precise their dental morphologies. A species from the Lutetian of Belgium, Carcharias sp., can be considered as the first representative of the lineage leading to the Recent species C. taurus. Three new genera are described: Brachycarcharias nov. gen. (Lutetian of Belgium), Orpodon nov. gen. (Selandian of Belgium) and Sylvestrilamia nov. gen. (Ypresian of England). The validity of the genus Hypotodus is confirmed and it is recommended that the poorly defined species hopei is abandoned in favour of the species verticalis in order to avoid confusion

Otolithes de poissons pliocènes du sud-est de la France

Otoliths collected from nine localities in the Lower and Middle Pliocene blue marls of southern France revealed the presence of 118 teleost taxa, including 80 named species. Three new species are introduced: Pseudophichthys escaravatierensis, "genus Bythitinorum" vonhachti and Cepola neogenica. The associations studied belong to five different biozones of planktonic foraminifera in the Lower and Middle Pliocene. The relationships of these Pliocene teleost faunas to the Tortonian and Recent Mediterranean faunas are analysed. Because major problems exist in matching otolith-based species with those erected for osteological material from Messinian localities, our comparisons are based exclusively on data obtained from the otoliths. Fifty of our 80 identified species appear only in the Pliocene. This indicates that at the beginning of the Piocene, the Mediterranean realm was subject to extensive faunal replacement. All the studied associations indicate higher temperatures than those of the present day Mediterranean. In the studied area, the associations from the basal Pliocene (Spaeroidinellopsis Acme-zone) at Saint-Martin-du-Var clearly indicate a bathyal environment, corresponding to depths of 300-500 m or even more. Ascending the stratigraphic column, the successive associations in the Pliocene rias of Southeastern France indicate decreasing depths, corresponding to the progressive filling of these basins. In the studied area, data on the teleosts of the terminal Pliocene are lacking, but faunas of this age are known from Southern Italy. They show that the Paleomediterranean fauna, which was substantially modified at the beginning of the Pliocene, appears near the end of this period as a warm water fauna, trapped in a basin where deterioration of climatic conditions led progressively to extinction. The Recent bathyal fauna of the Mediterranean appears extremely impoverished, but the littoral fauna conserves certain aspects of warmer waters, as is apparent in the prolific evolution of gobiids, labrids and blenniids

Sharks of the order Carcharhiniformes from the British Coniacian, Santonian and Campanian (Upper Cretaceous).

Bulk sampling of phosphate-rich horizons within the British Coniacian to Campanian (Upper Cretaceous) yielded very large samples of shark and ray teeth. All of these samples yielded teeth of diverse members of the Carcharhiniformes, which commonly dominate the fauna. The following species are recorded and described: Pseudoscyliorhinus reussi (Herman, 1977) comb. nov., Crassescyliorhinus germanicus (Herman, 1982) gen. nov., Scyliorhinus elongatus (Davis, 1887), Scyliorhinus brumarivulensis sp. nov., ? Palaeoscyllium sp., Prohaploblepharus riegrafi (Müller, 1989) gen. nov., ? Cretascyliorhinus sp., Scyliorhinidae inc. sedis 1, Scyliorhinidae inc. sedis 2, Pteroscyllium hermani sp. nov., Protoscyliorhinus sp., Leptocharias cretaceus sp. nov., Palaeogaleus havreensis Herman, 1977, Paratriakis subserratus sp. nov., Paratriakis tenuis sp. nov., Paratriakis sp. indet. and ? Loxodon sp. Taxa belonging to the families ?Proscylliidae, Leptochariidae, and Carcharhinidae are described from the Cretaceous for the first time. The evolutionary and palaeoecological implications of these newly recognised faunas are discussed

Searching for transits in the Wide Field Camera Transit Survey with difference-imaging light curves

The Wide Field Camera Transit Survey is a pioneer program aiming at for searching extra-solar planets in the near-infrared. The images from the survey are processed by a data reduction pipeline, which uses aperture photometry to construct the light curves. We produce an alternative set of light curves using the difference-imaging method for the most complete field in the survey and carry out a quantitative comparison between the photometric precision achieved with both methods. The results show that differencephotometry light curves present an important improvement for stars with J > 16. We report an implementation on the box-fitting transit detection algorithm, which performs a trapezoid-fit to the folded light curve, providing more accurate results than the boxfitting model. We describe and optimize a set of selection criteria to search for transit candidates, including the V-shape parameter calculated by our detection algorithm. The optimized selection criteria are applied to the aperture photometry and difference-imaging light curves, resulting in the automatic detection of the best 200 transit candidates from a sample of ~475 000 sources. We carry out a detailed analysis in the 18 best detections and classify them as transiting planet and eclipsing binary candidates. We present one planet candidate orbiting a late G-type star. No planet candidate around M-stars has been found, confirming the null detection hypothesis and upper limits on the occurrence rate of short-period giant planets around M-dwarfs presented in a prior study. We extend the search for transiting planets to stars with J ≤ 18, which enables us to set a stricter upper limit of 1.1%. Furthermore, we present the detection of five faint extremely-short period eclipsing binaries and three M-dwarf/M-dwarf binary candidates. The detections demonstrate the benefits of using the difference-imaging light curves, especially when going to fainter magnitudes.Peer reviewe

Four ultra-short period eclipsing M-dwarf binaries in the WFCAM Transit Survey

We report on the discovery of four ultra-short period (P<0.18 days) eclipsing M-dwarf binaries in the WFCAM Transit Survey. Their orbital periods are significantly shorter than of any other known main-sequence binary system, and are all significantly below the sharp period cut-off at P~0.22 days as seen in binaries of earlier type stars. The shortest-period binary consists of two M4 type stars in a P=0.112 day orbit. The binaries are discovered as part of an extensive search for short-period eclipsing systems in over 260,000 stellar lightcurves, including over 10,000 M-dwarfs down to J=18 mag, yielding 25 binaries with P<0.23 days. In a popular paradigm, the evolution of short period binaries of cool main-sequence stars is driven by loss of angular momentum through magnetised winds. In this scheme, the observed P~0.22 day period cut-off is explained as being due to timescales that are too long for lower-mass binaries to decay into tighter orbits. Our discovery of low-mass binaries with significantly shorter orbits implies that either these timescales have been overestimated for M-dwarfs, e.g. due to a higher effective magnetic activity, or that the mechanism for forming these tight M-dwarf binaries is different from that of earlier type main-sequence stars.Comment: 22 pages, 17 figures, 3 tables Accepted for publication in MNRA

Analytical Solution for the Deformation of a Cylinder under Tidal Gravitational Forces

Quite a few future high precision space missions for testing Special and General Relativity will use optical resonators which are used for laser frequency stabilization. These devices are used for carrying out tests of the isotropy of light (Michelson-Morley experiment) and of the universality of the gravitational redshift. As the resonator frequency not only depends on the speed of light but also on the resonator length, the quality of these measurements is very sensitive to elastic deformations of the optical resonator itself. As a consequence, a detailed knowledge about the deformations of the cavity is necessary. Therefore in this article we investigate the modeling of optical resonators in a space environment. Usually for simulation issues the Finite Element Method (FEM) is applied in order to investigate the influence of disturbances on the resonator measurements. However, for a careful control of the numerical quality of FEM simulations a comparison with an analytical solution of a simplified resonator model is beneficial. In this article we present an analytical solution for the problem of an elastic, isotropic, homogeneous free-flying cylinder in space under the influence of a tidal gravitational force. The solution is gained by solving the linear equations of elasticity for special boundary conditions. The applicability of using FEM codes for these simulations shall be verified through the comparison of the analytical solution with the results gained within the FEM code.Comment: 23 pages, 3 figure

The impact of the Pull of the Recent on extant elasmobranchs

Modern elasmobranchs have a long evolutionary history and an abundant fossil record that consists mainly of teeth. Many fossil taxa have living representatives. However, the representation of extant taxa in the fossil record is unknown. To begin to understand the geological history of extant elasmobranchs, we here assess the quality of their fossil record. We do so by assessing the Pull of the Recent (POR). The POR can bias the fossil record because the rather complete record of living taxa allows palaeontologists to identify fossil members of the modern clades and to bridge time bins where fossils are absent. We assessed the impact of the POR by quantifying the proportion of extant elasmobranchs that have a fossil record, but do not occur in the last 5 million years (Pliocene and Pleistocene). We found that the POR does not affect orders and families, but it does affect 24% of elasmobranch genera. Within the different elasmobranch orders, the Lamniformes display the most complete generic fossil record, with no impact of the POR. Although modest, the impact of the POR in extant elasmobranch genera is higher than that found in other taxa. Overall, the geological history of elasmobranchs contradicts the usual assumption that the fossil record becomes worse backwards in time. This is the case across geographical regions and tooth size, further suggesting that sampling intensity and outcrop availability might explain the POR effect on sharks and rays

The first three dimensional fossils of Cretaceous sclerorhynchid sawfish Asflapristis cristadentis gen et sp nov and implications for the phylogenetic position of the Sclerorhynchoidei (Chondrichthyes)

A new fossil batoid (ray) Asflapristis cristadentis gen. et sp. nov. is described from six exceptionally well-preserved, three-dimensional skeletal remains from the Turonian (Late Cretaceous) of Morocco. Mechanical and acid preparation and CT scanning of these specimens reveal details of much of the proximal skeleton, especially the skull, synarcual and pectoral skeleton, with only the more distal parts of the skeleton missing. These fossils represent a relatively large animal (62 cm preserved length, estimated total length to approximately 2 meters) possessing a robust rostrum that lacks enlarged rostral denticles. It has a narrow and small chondrocranium with jaws that are relatively large compared to the rest of the skull and robust with highly ornamented teeth that lack cusps. The branchial skeleton shows a large second hypobranchial without anterior process which was probably fused to the basibranchial as in other sclerorhynchoids. The synarcual is large and lacks centra through its entire length, and with no direct connection to the pectoral girdle was observed. Pectoral fins probably possessed enlarged proximal elements (propterygium, mesopterygium and metapterygium), the reduced articulation facet between the coracoid with the pectoral elements was reduced. A phylogenetic analysis using both parsimony and bayesian methods was performed incorporating this new taxon. Both analyses recovered a phylogenetic topology that places the sclerorhynchoids in a close relation to rajoids and clearly separated from the morphologically similar Pristidae within the Rhinopristiformes. In respect to the extant taxa, the phylogenies generated are similar to that obtained in molecular analysis of modern batoids. The palaeoecological implication of this discovery suggests that the Asfla assemblage was not from a ‘normal’ open carbonate shelf but rather a restricted environment favouring a low diversity chondrichthyan fauna

The Role of Renin-Angiotensin-Aldosterone System in the Heart and Lung: Focus on COVID-19

The renin-angiotensin-aldosterone system (RAAS) firstly considered as a cardiovascular circulating hormonal system, it is now accepted as a local tissue system that works synergistically or independently with the circulating one. Evidence states that tissue RAAS locally generates mediators with regulatory homeostatic functions, thus contributing, at some extent, to organ dysfunction or disease. Specifically, RAAS can be divided into the traditional RAAS pathway (or classic RAAS) mediated by angiotensin II (AII), and the non-classic RAAS pathway mediated by angiotensin 1–7. Both pathways operate in the heart and lung. In the heart, the classic RAAS plays a role in both hemodynamics and tissue remodeling associated with cardiomyocyte and endothelial dysfunction, leading to progressive functional impairment. Moreover, the local classic RAAS may predispose the onset of atrial fibrillation through different biological mechanisms involving inflammation, accumulation of epicardial adipose tissue, and electrical cardiac remodeling. In the lung, the classic RAAS regulates cell proliferation, immune-inflammatory response, hypoxia, and angiogenesis, contributing to lung injury and different pulmonary diseases (including COVID-19). Instead, the local non-classic RAAS counteracts the classic RAAS effects exerting a protective action on both heart and lung. Moreover, the non-classic RAAS, through the angiotensin-converting enzyme 2 (ACE2), mediates the entry of the etiological agent of COVID-19 (SARS-CoV-2) into cells. This may cause a reduction in ACE2 and an imbalance between angiotensins in favor of AII that may be responsible for the lung and heart damage. Drugs blocking the classic RAAS (angiotensin-converting enzyme inhibitors and angiotensin receptor blockers) are well known to exert a cardiovascular benefit. They are recently under evaluation for COVID-19 for their ability to block AII-induced lung injury altogether with drugs stimulating the non-classic RAAS. Herein, we discuss the available evidence on the role of RAAS in the heart and lung, summarizing all clinical data related to the use of drugs acting either by blocking the classic RAAS or stimulating the non-classic RAAS