A mechanism for biologically-induced iodine emissions from sea-ice

International audienceOnly recently, ground- and satellite-based measurements have reported high concentrations of IO in coastal Antarctica. The sources of such a large iodine burden in the Antarctic atmosphere remain unknown. We propose a novel mechanism for iodine release from sea-ice surfaces. The release is triggered by the biological production of iodide (I-) and hypoiodous acid (HOI) from marine algae, contained within and underneath sea-ice, and their diffusion through sea-ice brine channels to accumulate in the quasi-liquid layer on the surface of sea-ice. A multiphase chemical model of polar atmospheric chemistry has been developed to investigate the biology-ice-atmosphere coupling in the polar environment. Model simulations were conducted to interpret recent observations of elevated IO in the coastal Antarctic springtime. The results show that the levels of inorganic iodine (i.e. I2, IBr, ICl) released from sea-ice through this mechanism account for the observed IO concentrations in the Antarctic springtime environment. The model results also indicate that iodine may trigger the catalytic release of bromine from sea-ice through phase equilibration of IBr. Considering the extent of sea-ice around the Antarctic continent, we suggest that the resulting high levels of iodine may have widespread impact on catalytic ozone destruction and aerosol formation in the Antarctic lower troposphere

Multiprotein DNA looping

DNA looping plays a fundamental role in a wide variety of biological processes, providing the backbone for long range interactions on DNA. Here we develop the first model for DNA looping by an arbitrarily large number of proteins and solve it analytically in the case of identical binding. We uncover a switch-like transition between looped and unlooped phases and identify the key parameters that control this transition. Our results establish the basis for the quantitative understanding of fundamental cellular processes like DNA recombination, gene silencing, and telomere maintenance.Comment: 11 pages, 4 figure

Multiphase modeling of nitrate photochemistry in the quasi-liquid layer (QLL): implications for NOx release from the Arctic and coastal Antarctic snowpack

We utilize a multiphase model, CON-AIR (<B>Con</B>densed Phase to <B>Air</B> Transfer Model), to show that the photochemistry of nitrate (NO₃^&minus;) in and on ice and snow surfaces, specifically the quasi-liquid layer (QLL), can account for NO_x volume fluxes, concentrations, and [NO]/[NO₂] (γ=[NO]/[NO₂]) measured just above the Arctic and coastal Antarctic snowpack. Maximum gas phase NO_x volume fluxes, concentrations and γ simulated for spring and summer range from 5.0&times;10⁴ to 6.4&times;10⁵ molecules cm^&minus;3 s^&minus;1, 5.7&times;10⁸ to 4.8&times;10⁹ molecules cm^&minus;3, and ~0.8 to 2.2, respectively, which are comparable to gas phase NO_x volume fluxes, concentrations and γ measured in the field. The model incorporates the appropriate actinic solar spectrum, thereby properly weighting the different rates of photolysis of NO₃^&minus; and NO₂^&minus;. This is important since the immediate precursor for NO, for example, NO₂^&minus;, absorbs at wavelengths longer than nitrate itself. Finally, one-dimensional model simulations indicate that both gas phase boundary layer NO and NO₂ exhibit a negative concentration gradient as a function of height although [NO]/[NO₂] are approximately constant. This gradient is primarily attributed to gas phase reactions of NO_x with halogens oxides (i.e. as BrO and IO), HO_x, and hydrocarbons, such as CH₃O₂

Caracterización mecánica de pistas deportivas fabricadas con materiales procedentes de neumáticos fuera de uso (NFU)

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.The European Framework Directive 2008/98/EC on waste established as priority reuse and recycling before other recovery alternatives. In this normative reference, one the main waste flows identified are the end-of-life tyres, as a material whose mechanical properties could provide advantage in the construction of new structures. This paper presents the mechanical characterization of a layer made with shredded tires out of use, inside a section of a sportive track which included a sand layer. The use of the shredded tires out of use provides special features related with elasticity and damping to the sportive surface. In order to do that, a new test based on UNE-14809 was designed. A number of tests were performed using different configuration of sand and shredded tires. From the results obtained, a numerical model was implemented in FEA software

BDNF and NGF Signalling in Early Phases of Psychosis: Relationship with Inflammation and Response to Antipsychotics after 1 Year

This work was supported by the Spanish Ministry of Economy and Competiveness and the Carlos III Health Institute through CIBERSAM, and the Foundation Santander-UCM (GR 58/08), and partly supported by the Spanish Ministry of Economy and Competiveness directly, and by the European Regional Development Fund, FEDER (PI10/01746, PI11/01977, PI11/02708,PI12/02077), local grants from the Department of Education, Linguistic Policy and Culture of the Basque Country Government (2010111170, 2010112009), the Basque Foundation for Health Innovation and Research (BIOEF), ) and the University of the Basque Country (GIC10/80, GIC12/84).Martinez-Cengotitabengoa, M., Macdowell, K.S., Alberich, S., Diaz, F.J., Garcia-Bueno, B., Rodriguez-Jimenez, R., Bioque, M., Berrocoso, E., Parellada, M., Lobo, A., Saiz, P.A., Matute, C., Bernardo, M., Gonzalez-Pinto, A., Leza, J.C

Conservation Laws in Smooth Particle Hydrodynamics: the DEVA Code

We describe DEVA, a multistep AP3M-like-SPH code particularly designed to study galaxy formation and evolution in connection with the global cosmological model. This code uses a formulation of SPH equations which ensures both energy and entropy conservation by including the so-called \bn h terms. Particular attention has also been paid to angular momentum conservation and to the accuracy of our code. We find that, in order to avoid unphysical solutions, our code requires that cooling processes must be implemented in a non-multistep way. We detail various cosmological simulations which have been performed to test our code and also to study the influence of the \bn h terms. Our results indicate that such correction terms have a non-negligible effect on some cosmological simulations, especially on high density regions associated either to shock fronts or central cores of collapsed objects. Moreover, they suggest that codes paying a particular attention to the implementation of conservation laws of physics at the scales of interest, can attain good accuracy levels in conservation laws with limited computational resources.Comment: 36 pages, 10 figures. Accepted for publication in The Astrophysical Journa