624 research outputs found
Agriopleura Morphotypes of the Lower Aptian Shuâaiba Formation of Saudi Arabia
The Shuâaiba Formation of the Arabian Platform consists of Aptian carbonates in which rudists are important biocomponents. It is an important hydrocarbon reservoir. Semi quantitative micropalaeontology and macropalaeontological observations from cores have enabled three-dimensional interpretation of biofacies and lithofacies that have guided optimal reservoir exploitation.
In addition to the presence of Offneria murgensis MASSE, O. cf. nicolinae (MAINELLI), Glossomyophorus costatus MASSE et al., Oedomyophorus shaybahensis SKELTON, and Horiopleura cf. distefanoi BOEHM the Shuâaiba Formation contains Agriopleura cf. blumenbachi (STUDER) and A. cf. marticensis (dâORBIGNY). Although species of Agriopleura are locally present over short sections below the Glossomyophorus costatus accumulations of the middle part of the formation, they are very well represented in its upper part, where they are typically associated with the moderately deep marine benthonic foraminifera Praechrysalidina infracretacea, Vercorsella arenata, Debarina hahounerensis and Palorbitolina lenticularis.
Agriopleura cf. blumenbachi and A. cf. marticensis display contrasting morphologies. Agriopleura cf. marticensis is cone-shaped, with a fixed valve expansion angle of 30â35°, and with average right valve dimensions of 3.5 cm length and 2.5 cm maximum diameter. A recently observed âclingerâ form is, however, 70 cm long. A. cf. blumenbachi is elongate, almost tube-like, with a very low rate of fixed valve diameter increase, of less than 10° with average right valve dimensions of 6.5 cm length and 2.2 cm maximum diameter.
The two forms are present in distinct biofacies. Both Agriopleura facies are considered to compose a single depositional cycle, and it is possible that the elongate shape of Agriopleura cf. blumenbachi is better adapted to the slightly higher rate of sedimentation associated with the relatively rapid sea level rise at the base of each new depositional cycle. The cone-shape of A. cf. marticensis is possibly adapted to lower rates of sedimentation during the relatively slower rate of sea level rise, and ultimate fall of the upper part of each depositional cycle
Agriopleura Morphotypes of the Lower Aptian Shuâaiba Formation of Saudi Arabia
The Shuâaiba Formation of the Arabian Platform consists of Aptian carbonates in which rudists are important biocomponents. It is an important hydrocarbon reservoir. Semi quantitative micropalaeontology and macropalaeontological observations from cores have enabled three-dimensional interpretation of biofacies and lithofacies that have guided optimal reservoir exploitation.
In addition to the presence of Offneria murgensis MASSE, O. cf. nicolinae (MAINELLI), Glossomyophorus costatus MASSE et al., Oedomyophorus shaybahensis SKELTON, and Horiopleura cf. distefanoi BOEHM the Shuâaiba Formation contains Agriopleura cf. blumenbachi (STUDER) and A. cf. marticensis (dâORBIGNY). Although species of Agriopleura are locally present over short sections below the Glossomyophorus costatus accumulations of the middle part of the formation, they are very well represented in its upper part, where they are typically associated with the moderately deep marine benthonic foraminifera Praechrysalidina infracretacea, Vercorsella arenata, Debarina hahounerensis and Palorbitolina lenticularis.
Agriopleura cf. blumenbachi and A. cf. marticensis display contrasting morphologies. Agriopleura cf. marticensis is cone-shaped, with a fixed valve expansion angle of 30â35°, and with average right valve dimensions of 3.5 cm length and 2.5 cm maximum diameter. A recently observed âclingerâ form is, however, 70 cm long. A. cf. blumenbachi is elongate, almost tube-like, with a very low rate of fixed valve diameter increase, of less than 10° with average right valve dimensions of 6.5 cm length and 2.2 cm maximum diameter.
The two forms are present in distinct biofacies. Both Agriopleura facies are considered to compose a single depositional cycle, and it is possible that the elongate shape of Agriopleura cf. blumenbachi is better adapted to the slightly higher rate of sedimentation associated with the relatively rapid sea level rise at the base of each new depositional cycle. The cone-shape of A. cf. marticensis is possibly adapted to lower rates of sedimentation during the relatively slower rate of sea level rise, and ultimate fall of the upper part of each depositional cycle
Computerized Tomography Reveals Aptian Rudist Species and Taphonomy
Computerized tomographic (CT) scans of cored carbonates from the Lower Aptian Shuâaiba Formation reveal clearly defined rudist profiles. Formation MicroImager (FMI) logs from the equivalent cored wellbore also display images related to the rudist content. Various rudist species can be identified in the cores and provide a key to the identification of the CT and FMI rudist images. As certain rudist species preferentially occupied different environments during the Early Aptian deposition of the Shuâaiba Formation carbonates, their recognition in the cores, CT and FMI images can be used to assist determination of palaeoenvironments, lithofacies and reservoir facies. This new ability to identify rudist images in FMI logs in uncored development wells can be used to extend depositional facies models into uncored parts of the hydrocarbon reservoir models
Arterial inflammation in mice lacking the interleukin 1 receptor antagonist gene
Branch points and flexures in the high pressure arterial system have long been recognized as sites of unusually high turbulence and consequent stress in humans are foci for atherosclerotic lesions. We show that mice that are homozygous for a null mutation in the gene encoding an endogenous antiinflammatory cytokine, interleukin 1 receptor antagonist (IL-1ra), develop lethal arterial inflammation involving branch points and flexures of the aorta and its primary and secondary branches. We observe massive transmural infiltration of neutrophils, macrophages, and CD4(+) T cells. Animals appear to die from vessel wall collapse, stenosis, and organ infarction or from hemorrhage from ruptured aneurysms. Heterozygotes do not die from arteritis within a year of birth but do develop small lesions, which suggests that a reduced level of IL-1ra is insufficient to fully control inflammation in arteries. Our results demonstrate a surprisingly specific role for IL-1ra in the control of spontaneous inflammation in constitutively stressed artery walls, suggesting that expression of IL-1 is likely to have a significant role in signaling artery wall damage
Towards a farmer-feasible soil health assessment that is globally applicable
Acknowledgements This work was supported by a NERC (Natural Environment Research Council) Doctoral Training Partnership grant (NE/S007407/1), Syngenta Crop Protection AG and the ClieNFarms project which received funding from the European Unionâs Horizon 2020 Societal Challenges Program under the grant agreement No 101036822. For the purpose of open access, the authors have applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission.Peer reviewedPostprin
Relativistic nuclear recoil corrections to the energy levels of hydrogen-like and high lithium like atoms in all orders in
The relativistic nuclear recoil corrections to the energy levels of
low-laying states of hydrogen-like and high lithium-like atoms in all
orders in are calculated. The calculations are carried out using the
B-spline method for the Dirac equation.
For low the results of the calculation are in good agreement with the
-expansion results. It is found that the nuclear recoil
contribution, additional to the Salpeter's one, to the Lamb shift () of
hydrogen is . The total nuclear recoil correction to the energy
of the transition in lithium-like uranium
constitutes and is largely made up of QED contributions.Comment: 19 pages, latex, accepted for publication in Phys. Rev.
Implications of the Muon Anomalous Magnetic Moment for Supersymmetry
We re-examine the bounds on supersymmetric particle masses in light of the
E821 data on the muon anomalous magnetic moment. We confirm, extend and
supersede previous bounds. In particular we find (at one sigma) no lower limit
on tan(beta) or upper limit on the chargino mass implied by the data at
present, but at least 4 sparticles must be lighter than 700 to 820 GeV and at
least one sparticle must be lighter than 345 to 440 GeV. However, the E821
central value bounds tan(beta) > 4.7 and the lighter chargino mass by 690 GeV.
For tan(beta) < 10, the data indicates a high probability for direct discovery
of SUSY at Run II or III of the Tevatron.Comment: 20 pages LaTeX, 14 figures; references adde
Moderate deviations via cumulants
The purpose of the present paper is to establish moderate deviation
principles for a rather general class of random variables fulfilling certain
bounds of the cumulants. We apply a celebrated lemma of the theory of large
deviations probabilities due to Rudzkis, Saulis and Statulevicius. The examples
of random objects we treat include dependency graphs, subgraph-counting
statistics in Erd\H{o}s-R\'enyi random graphs and -statistics. Moreover, we
prove moderate deviation principles for certain statistics appearing in random
matrix theory, namely characteristic polynomials of random unitary matrices as
well as the number of particles in a growing box of random determinantal point
processes like the number of eigenvalues in the GUE or the number of points in
Airy, Bessel, and random point fields.Comment: 24 page
Unified dark energy models : a phenomenological approach
A phenomenological approach is proposed to the problem of universe
accelerated expansion and of the dark energy nature. A general class of models
is introduced whose energy density depends on the redshift in such a way
that a smooth transition among the three main phases of the universe evolution
(radiation era, matter domination, asymptotical de Sitter state) is naturally
achieved. We use the estimated age of the universe, the Hubble diagram of Type
Ia Supernovae and the angular size - redshift relation for compact and
ultracompact radio structures to test whether the model is in agreement with
astrophysical observation and to constrain its main parameters. Although
phenomenologically motivated, the model may be straightforwardly interpreted as
a two fluids scenario in which the quintessence is generated by a suitably
chosen scalar field potential. On the other hand, the same model may also be
read in the context of unified dark energy models or in the framework of
modified Friedmann equation theories.Comment: 12 pages, 10 figures, accepted for publication on Physical Review
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