674 research outputs found
Chemotrophic Microbial Mats and Their Potential for Preservation in the Rock Record
Putative microbialites are commonly regarded to have formed in association with photosynthetic microorganisms, such as cyanobacteria. However, many modern microbial mat ecosystems are dominated by chemotrophic bacteria and archaea. Like phototrophs, filamentous sulfur-oxidizing bacteria form large mats at the sediment/water interface that can act to stabilize sediments, and their metabolic activities may mediate the formation of marine phosphorites. Similarly, bacteria and archaea associated with the anaerobic oxidation of methane (AOM) catalyze the precipitation of seafloor authigenic carbonates. When preserved, lipid biomarkers, isotopic signatures, body fossils, and lithological indicators of the local depositional environment may be used to identify chemotrophic mats in the rock record. The recognition of chemotrophic communities in the rock record has the potential to transform our understanding of ancient microbial ecologies, evolution, and geochemical conditions. Chemotrophic microbes on Earth occupy naturally occurring interfaces between oxidized and reduced chemical species and thus may provide a new set of search criteria to target life-detection efforts on other planets
Optimal finite-range atomic basis sets for liquid water and ice.
Finite-range numerical atomic orbitals are the basis functions of choice for several first principles methods, due to their flexibility and scalability. Generating and testing such basis sets, however, remains a significant challenge for the end user. We discuss these issues and present a new scheme for generating improved polarization orbitals of finite range. We then develop a series of high-accuracy basis sets for the water molecule, and report on their performance in describing the monomer and dimer, two phases of ice, and liquid water at ambient and high density. The tests are performed by comparison with plane-wave calculations, and show the atomic orbital basis sets to exhibit an excellent level of transferability and consistency. The highest-order bases (quadruple-ζ) are shown to give accuracies comparable to a plane-wave kinetic energy cutoff of at least ~1000 eV for quantities such as energy differences and ionic forces, as well as achieving significantly greater accuracies for total energies and absolute pressures
APPLICATION OF LASER SCANNING SURVEYING TO ROCK SLOPES RISK ASSESSMENT ANALYSIS
The methods for understanding rock instability mechanisms and for evaluating potential destructive scenarios are of great importance in risk assessment analysis dedicated to the establishment of appropriate prevention and mitigation actions. When the portion of the unstable rock mass is very large, effective actions to counteract the risks are complex and expensive. In these conditions, an optimal risk management cannot ignore procedures able to faster and accurately acquire i) geometrical data for modeling the geometry of the rock walls and implementing reliable forecasting models and ii) monitoring data able to describe the magnitude and the direction of deformation processes. These data contributes to the prediction of the behavior of a landslide if the measurements are acquired frequently and reliable numerical models can be implemented. Innovative geomatic techniques, based on GPS, Terrestrial Laser Scanning Surveying (TLS), automated total station and satellite and ground SAR Interferometry, have been recently applied to define the geometry and monitoring the displacements of unstable slopes. Among these, TLS is mainly adopted to generate detailed 3D models useful to reconstruct rock wall geometry by contributing to the estimation of geo-mechanical parameters, that is orientation, persistence and apparent spacing of rock discontinuities. Two examples of applications of TLS technique to the analysis of a large front in a quarry and of a rock shoulder of a dam are presented
Neutrino Fluxes from CMSSM LSP Annihilations in the Sun
We evaluate the neutrino fluxes to be expected from neutralino LSP
annihilations inside the Sun, within the minimal supersymmetric extension of
the Standard Model with supersymmetry-breaking scalar and gaugino masses
constrained to be universal at the GUT scale (the CMSSM). We find that there
are large regions of typical CMSSM planes where the LSP
density inside the Sun is not in equilibrium, so that the annihilation rate may
be far below the capture rate. We show that neutrino fluxes are dependent on
the solar model at the 20% level, and adopt the AGSS09 model of Serenelli et
al. for our detailed studies. We find that there are large regions of the CMSSM
planes where the capture rate is not dominated by
spin-dependent LSP-proton scattering, e.g., at large along the CMSSM
coannihilation strip. We calculate neutrino fluxes above various threshold
energies for points along the coannihilation/rapid-annihilation and focus-point
strips where the CMSSM yields the correct cosmological relic density for
tan(beta) = 10 and 55 for > 0, exploring their sensitivities to
uncertainties in the spin-dependent and -independent scattering matrix
elements. We also present detailed neutrino spectra for four benchmark models
that illustrate generic possibilities within the CMSSM. Scanning the
cosmologically-favored parts of the parameter space of the CMSSM, we find that
the IceCube/DeepCore detector can probe at best only parts of this parameter
space, notably the focus-point region and possibly also at the low-mass tip of
the coannihilation strip.Comment: 32 pages, 13 figures. v2: updated/expanded discussion of
IceCube/DeepCor
Room temperature compressibility and diffusivity of liquid water from first principles.
The isothermal compressibility of water is essential to understand its anomalous properties. We compute it by ab initio molecular dynamics simulations of 200 molecules at five densities, using two different van der Waals density functionals. While both functionals predict compressibilities within ~30% of experiment, only one of them accurately reproduces, within the uncertainty of the simulation, the density dependence of the self-diffusion coefficient in the anomalous region. The discrepancies between the two functionals are explained in terms of the low- and high-density structures of the liquid
A systematic construction of completely integrable Hamiltonians from coalgebras
A universal algorithm to construct N-particle (classical and quantum)
completely integrable Hamiltonian systems from representations of coalgebras
with Casimir element is presented. In particular, this construction shows that
quantum deformations can be interpreted as generating structures for integrable
deformations of Hamiltonian systems with coalgebra symmetry. In order to
illustrate this general method, the algebra and the oscillator
algebra are used to derive new classical integrable systems including a
generalization of Gaudin-Calogero systems and oscillator chains. Quantum
deformations are then used to obtain some explicit integrable deformations of
the previous long-range interacting systems and a (non-coboundary) deformation
of the Poincar\'e algebra is shown to provide a new
Ruijsenaars-Schneider-like Hamiltonian.Comment: 26 pages, LaTe
Protect and Counter-attack: Nutritional Supplementation with Essential Amino acid Ratios Reduces Doxorubicin induced Cardiotoxicity in vivo and promote Cancer Cell Death in vitro
Giovanni Corsetti1*, Vincenzo Flati2, Patrizia Sanita2, Evasio Pasini3 and Francesco Saverio Dioguardi4 1Department of Clinical & Experimental Sciences, Division of Human Anatomy & Physiopathology, University of Brescia, Brescia, Italy 2Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy 3"S. Maugeri Fundation", IRCCS, Cardiology Rehabilitative Division, Medical Centre of Lumezzane, Lumezzane (Brescia), Italy 4Department of Internal Medicine and Community Health, University of Milan, Milan, Italy *Corresponding author: Giovanni Corsetti, Department of Clinical & Experimental Sciences, Division of Human Anatomy and Physiopathology, University of Brescia, v.le Europa, 11; 25124 Brescia, Italy, Tel: +39 030 3717484; Fax: +39 030 3717486; E-mail: [email protected]
Mammography: EUSOBI recommendations for women’s information
This paper summarises the basic information to be offered to women who undergo mammography. After a delineation of the general aim of early diagnosis of breast cancer, the main difference between screening mammography and diagnostic mammography is explained. The best time for scheduling mammography in fertile women is defined. The need to bring images and reports from the previous mammogram (and from other recent breast imaging examinations) is highlighted. The technique and procedure of mammography are briefly described with particular attention to discomfort and pain experienced by a fraction of women who undergo the test. Information is given on the recall during a screening program and on the request for further work-up after a diagnostic mammography. The logic of the diagnostic mammography report and of classification systems such as BI-RADS and R1-R5 is illustrated, and brief but clear information is given about the diagnostic performance of the test, with particular reference to interval cancers. Moreover, the breast cancer risk due to radiation exposure from mammography is compared to the reduction in mortality obtained with the test, and the concept of overdiagnosis is presented. Finally, five frequently asked questions are answered
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