A Bayesian model for anchovy (Engraulis encrasicolus): the combined forcing of man and environment

Fishery collapses frequently result from combined pressures of the environment and man, which are difficult to discern because of the complexities involved and our limited knowledge. Models to resolve this complexity often become too sophisticated, with too many assumptions and, consequently, with little capacity to predict beyond calibration data. In this paper we implement a different procedure where the model is kept simple and uncertainty accounts for the equation imperfectness to reproduce ecological complexity. Human and environmental forcing on an anchovy (Engraulis encrasicolus) stock are simulated with only six parameters plus their error terms, and the uncertainty is computed with Bayesian methods. The simple structure is able to reproduce the major dynamical features of this species in the Gulf of Ca´diz, including data on life stages and age structure that had no contact with the model. This is a distinct performance for a frugal approach working on a mid-trophic species and a positive instance where parsimony can simulate the interaction of man, fish and the environment, provided uncertainty is accounted for in the process.Publicado

On the monitoring of surface displacement in connection with volcano reactivation in Tenerife, Canary Islands, using space techniques

Geodetic volcano monitoring in Tenerife has mainly focused on the Las Cañadas Caldera, where a geodetic micronetwork and a levelling profile are located. A sensitivity test of this geodetic network showed that it should be extended to cover the whole island for volcano monitoring purposes. Furthermore, InSAR allowed detecting two unexpected movements that were beyond the scope of the traditional geodetic network. These two facts prompted us to design and observe a GPS network covering the whole of Tenerife that was monitored in August 2000. The results obtained were accurate to one centimetre, and confirm one of the deformations, although they were not definitive enough to confirm the second one. Furthermore, new cases of possible subsidence have been detected in areas where InSAR could not be used to measure deformation due to low coherence. A first modelling attempt has been made using a very simple model and its results seem to indicate that the deformation observed and the groundwater level variation in the island may be related. Future observations will be necessary for further validation and to study the time evolution of the displacements, carry out interpretation work using different types of data (gravity, gases, etc) and develop models that represent the island more closely. The results obtained are important because they might affect the geodetic volcano monitoring on the island, which will only be really useful if it is capable of distinguishing between displacements that might be linked to volcanic activity and those produced by other causes. One important result in this work is that a new geodetic monitoring system based on two complementary techniques, InSAR and GPS, has been set up on Tenerife island. This the first time that the whole surface of any of the volcanic Canary Islands has been covered with a single network for this purpose. This research has displayed the need for further similar studies in the Canary Islands, at least on the islands which pose a greater risk of volcanic reactivation, such as Lanzarote and La Palma, where InSAR techniques have been used already

The 5 Objects Test: Normative data from a Spanish community sample

[EN]Objective: The objective of this study was to provide normative data for the 5 Objects Test in a large Spanish community sample, as well as some validity evidence. Methods: The sample was composed of 427 participants (of which 220 females, age 15 to 95 years old; educational level range: 2–17 years). Normative data are provided, as well as correlations with test scores from Benton Visual Retention test, Rey-Osterrieth Complex Figure and Mini Mental State Examination. Results: No association was found between delayed recall score and level of education, age or gender. Immediate recall score was correlated with age. Both immediate and delayed recall significantly correlated with the criteria, evidencing concurrent validity. Conclusions: It is recommended that the 5 Objects Test be used for assessing persons in primary care, including those from different linguistic backgrounds or with limited language use. Delayed recall scores are especially recommended given the lack of association with demographic variables

Comparison of Maldi-Tof with gene sequencing in bacteria isolates from plants belonging to family Rhizobiaceae

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Metal-Specific Reactivity in Single-Atom Catalysts: CO Oxidation on 4d and 5d Transition Metals Atomically Dispersed on MgO

[EN] Understanding and tuning the catalytic properties of metals atomically dispersed on oxides are major stepping-stones toward a rational development of single-atom catalysts (SACs). Beyond individual showcase studies, the design and synthesis of structurally regular series of SACs opens the door to systematic experimental investigations of performance as a function of metal identity. Herein, a series of single-atom catalysts based on various 4d (Ru, Rh, Pd) and Sd (Ir, Pt) transition metals has been synthesized on a common MgO carrier. Complementary experimental (X-ray absorption spectroscopy) and theoretical (Density Functional Theory) studies reveal that, regardless of the metal identity, metal cations occupy preferably octahedral coordination MgO lattice positions under step-edges, hence highly confined by the oxide support. Upon exposure to O-2-lean CO oxidation conditions, FTIR spectroscopy indicates the partial deconfinement of the monatomic metal centers driven by CO at precatalysis temperatures, followed by the development of surface carbonate species under steady-state conditions. These findings are supported by DFT calculations, which show the driving force and final structure for the surface metal protrusion to be metal-dependent, but point to an equivalent octahedral-coordinated M4+ carbonate species as the resting state in all cases. Experimentally, apparent reaction activation energies in the range of 96 +/- 19 kJ/mol are determined, with Pt leading to the lowest energy barrier. The results indicate that, for monatomic sites in SACs, differences in CO oxidation reactivity enforceable via metal selection are of lower magnitude than those evidenced previously through the mechanistic involvement of adjacent redox centers on the oxide carrier, suggesting that tuning of the oxide surface chemistry is as relevant as the selection of the supported metal.XAS experiments were performed at B18 beamline, Diamond Light Source, United Kingdom (proposals Nr. SP17377 and SP19072) and BL22 beamline, ALBA Light Source, Spain (experiment 2019023278). Beamline scientists D. Gianolio (Diamond) and L. Simonelli and C. Marini (ALBA) are acknowledged for their assistance with the beamline setup during XAS experiments. The authors are grateful to M. Garcia, E. Andres, M. E. Martinez, and I. Lopez (ITQ) for assistance during the XAS experiments. J. Ternieden (MPIKOFO) is acknowledged for the performance of XRD experiments. J.M. Salas (ITQ) is acknowledged for his experimental contribution to the CO-FTIR studies, and M.D. Soriano and A. Munoz for the recording of XP spectra. P.N.P. and F.S. acknowledge support by the state of BademWurttemberg through bwHPC (bwUnicluster and JUSTUS, RV bw17D01) and support from the Helmholtz Association is also gratefully acknowledged. This research received funding from the Alexander von Humboldt Foundation (postdoctoral grant to B.B.S.), the Max Planck Society and the Fonds der Chemischen Industry (FCI, Germany). The authors are grateful to Prof. Ferdi Schuth for the provision of lab facilities and support throughout the project. Funding from the Spanish Ministry of Science, Innovation and Universities (projects SEV 2016-0683 and RTI2018-096399-A-100) is also acknowledged.Sarma, BB.; Plessow, PN.; Agostini, G.; Concepción Heydorn, P.; Pfänder, N.; Kang, L.; Wang, FR.... (2020). Metal-Specific Reactivity in Single-Atom Catalysts: CO Oxidation on 4d and 5d Transition Metals Atomically Dispersed on MgO. Journal of the American Chemical Society. 142(35):14890-14902. https://doi.org/10.1021/jacs.0c03627S148901490214235Ruckenstein, E., & Hu, X. D. (1985). Mechanism of redispersion of supported metal catalysts in oxidative atmospheres. Langmuir, 1(6), 756-760. doi:10.1021/la00066a019Szymura, J. A. (1986). Studies on Redispersion and Stability of Platinum in Pt/MgO System during Oxygen Treatment at High Temperatures. Zeitschrift f�r anorganische und allgemeine Chemie, 542(11), 232-240. doi:10.1002/zaac.19865421130Morgan, K., Goguet, A., & Hardacre, C. (2015). Metal Redispersion Strategies for Recycling of Supported Metal Catalysts: A Perspective. ACS Catalysis, 5(6), 3430-3445. doi:10.1021/acscatal.5b00535Qiao, B., Wang, A., Yang, X., Allard, L. F., Jiang, Z., Cui, Y., … Zhang, T. (2011). Single-atom catalysis of CO oxidation using Pt1/FeOx. Nature Chemistry, 3(8), 634-641. doi:10.1038/nchem.1095Jones, J., Xiong, H., DeLaRiva, A. T., Peterson, E. J., Pham, H., Challa, S. R., … Datye, A. K. (2016). Thermally stable single-atom platinum-on-ceria catalysts via atom trapping. Science, 353(6295), 150-154. doi:10.1126/science.aaf8800Kunwar, D., Zhou, S., DeLaRiva, A., Peterson, E. J., Xiong, H., Pereira-Hernández, X. I., … Datye, A. K. (2019). Stabilizing High Metal Loadings of Thermally Stable Platinum Single Atoms on an Industrial Catalyst Support. ACS Catalysis, 9(5), 3978-3990. doi:10.1021/acscatal.8b04885Liu, L., Zakharov, D. N., Arenal, R., Concepcion, P., Stach, E. A., & Corma, A. (2018). Evolution and stabilization of subnanometric metal species in confined space by in situ TEM. Nature Communications, 9(1). doi:10.1038/s41467-018-03012-6Sarma, B. B., Kim, J., Amsler, J., Agostini, G., Weidenthaler, C., Pfänder, N., … Prieto, G. (2020). One‐Pot Cooperation of Single‐Atom Rh and Ru Solid Catalysts for a Selective Tandem Olefin Isomerization‐Hydrosilylation Process. Angewandte Chemie International Edition, 59(14), 5806-5815. doi:10.1002/anie.201915255Yang, X.-F., Wang, A., Qiao, B., Li, J., Liu, J., & Zhang, T. (2013). Single-Atom Catalysts: A New Frontier in Heterogeneous Catalysis. Accounts of Chemical Research, 46(8), 1740-1748. doi:10.1021/ar300361mGates, B. C., Flytzani-Stephanopoulos, M., Dixon, D. A., & Katz, A. (2017). Atomically dispersed supported metal catalysts: perspectives and suggestions for future research. Catalysis Science & Technology, 7(19), 4259-4275. doi:10.1039/c7cy00881cWang, A., Li, J., & Zhang, T. (2018). Heterogeneous single-atom catalysis. Nature Reviews Chemistry, 2(6), 65-81. doi:10.1038/s41570-018-0010-1Amsler, J., Sarma, B. B., Agostini, G., Prieto, G., Plessow, P. N., & Studt, F. (2020). Prospects of Heterogeneous Hydroformylation with Supported Single Atom Catalysts. Journal of the American Chemical Society, 142(11), 5087-5096. doi:10.1021/jacs.9b12171Cui, X., Li, W., Ryabchuk, P., Junge, K., & Beller, M. (2018). Bridging homogeneous and heterogeneous catalysis by heterogeneous single-metal-site catalysts. Nature Catalysis, 1(6), 385-397. doi:10.1038/s41929-018-0090-9Uzun, A., Ortalan, V., Browning, N. D., & Gates, B. C. (2010). A site-isolated mononuclear iridium complex catalyst supported on MgO: Characterization by spectroscopy and aberration-corrected scanning transmission electron microscopy. Journal of Catalysis, 269(2), 318-328. doi:10.1016/j.jcat.2009.11.017Chen, Y., Ji, S., Sun, W., Chen, W., Dong, J., Wen, J., … Li, Y. (2018). Discovering Partially Charged Single-Atom Pt for Enhanced Anti-Markovnikov Alkene Hydrosilylation. Journal of the American Chemical Society, 140(24), 7407-7410. doi:10.1021/jacs.8b03121Zhang, X., Sun, Z., Wang, B., Tang, Y., Nguyen, L., Li, Y., & Tao, F. F. (2018). C–C Coupling on Single-Atom-Based Heterogeneous Catalyst. Journal of the American Chemical Society, 140(3), 954-962. doi:10.1021/jacs.7b09314Chen, Z., Vorobyeva, E., Mitchell, S., Fako, E., Ortuño, M. A., López, N., … Pérez-Ramírez, J. (2018). A heterogeneous single-atom palladium catalyst surpassing homogeneous systems for Suzuki coupling. Nature Nanotechnology, 13(8), 702-707. doi:10.1038/s41565-018-0167-2Millet, M.-M., Algara-Siller, G., Wrabetz, S., Mazheika, A., Girgsdies, F., Teschner, D., … Frei, E. (2019). Ni Single Atom Catalysts for CO2 Activation. Journal of the American Chemical Society, 141(6), 2451-2461. doi:10.1021/jacs.8b11729Li, J., Guan, Q., Wu, H., Liu, W., Lin, Y., Sun, Z., … Lu, J. (2019). Highly Active and Stable Metal Single-Atom Catalysts Achieved by Strong Electronic Metal–Support Interactions. Journal of the American Chemical Society, 141(37), 14515-14519. doi:10.1021/jacs.9b06482Tang, Y., Wei, Y., Wang, Z., Zhang, S., Li, Y., Nguyen, L., … Hu, P. (2019). Synergy of Single-Atom Ni1 and Ru1 Sites on CeO2 for Dry Reforming of CH4. Journal of the American Chemical Society, 141(18), 7283-7293. doi:10.1021/jacs.8b10910Malta, G., Kondrat, S. A., Freakley, S. J., Davies, C. J., Lu, L., Dawson, S., … Hutchings, G. J. (2017). Identification of single-site gold catalysis in acetylene hydrochlorination. Science, 355(6332), 1399-1403. doi:10.1126/science.aal3439Falsig, H., Hvolbæk, B., Kristensen, I. S., Jiang, T., Bligaard, T., Christensen, C. H., & Nørskov, J. K. (2008). Trends in the Catalytic CO Oxidation Activity of Nanoparticles. Angewandte Chemie International Edition, 47(26), 4835-4839. doi:10.1002/anie.200801479Latimer, A. A., Kulkarni, A. R., Aljama, H., Montoya, J. H., Yoo, J. S., Tsai, C., … Nørskov, J. K. (2016). Understanding trends in C–H bond activation in heterogeneous catalysis. Nature Materials, 16(2), 225-229. doi:10.1038/nmat4760Hensen, E. J. M., Brans, H. J. A., Lardinois, G. M. H. J., de Beer, V. H. J., van Veen, J. A. R., & van Santen, R. A. (2000). Periodic Trends in Hydrotreating Catalysis: Thiophene Hydrodesulfurization over Carbon-Supported 4d Transition Metal Sulfides. Journal of Catalysis, 192(1), 98-107. doi:10.1006/jcat.2000.2824Thornburg, N. E., Thompson, A. B., & Notestein, J. M. (2015). Periodic Trends in Highly Dispersed Groups IV and V Supported Metal Oxide Catalysts for Alkene Epoxidation with H2O2. ACS Catalysis, 5(9), 5077-5088. doi:10.1021/acscatal.5b01105Yang, T., Fukuda, R., Hosokawa, S., Tanaka, T., Sakaki, S., & Ehara, M. (2017). A Theoretical Investigation on CO Oxidation by Single-Atom Catalysts M1 /γ-Al2 O3 (M=Pd, Fe, Co, and Ni). ChemCatChem, 9(7), 1222-1229. doi:10.1002/cctc.201601713Kropp, T., Lu, Z., Li, Z., Chin, Y.-H. C., & Mavrikakis, M. (2019). Anionic Single-Atom Catalysts for CO Oxidation: Support-Independent Activity at Low Temperatures. ACS Catalysis, 9(2), 1595-1604. doi:10.1021/acscatal.8b03298O’Connor, N. J., Jonayat, A. S. M., Janik, M. J., & Senftle, T. P. (2018). Interaction trends between single metal atoms and oxide supports identified with density functional theory and statistical learning. Nature Catalysis, 1(7), 531-539. doi:10.1038/s41929-018-0094-5Tanaka, I., Oba, F., Tatsumi, K., Kunisu, M., Nakano, M., & Adachi, H. (2002). Theoretical Formation Energy of Oxygen-Vacancies in Oxides. MATERIALS TRANSACTIONS, 43(7), 1426-1429. doi:10.2320/matertrans.43.1426Therrien, A. J., Hensley, A. J. R., Marcinkowski, M. D., Zhang, R., Lucci, F. R., Coughlin, B., … Sykes, E. C. H. (2018). An atomic-scale view of single-site Pt catalysis for low-temperature CO oxidation. Nature Catalysis, 1(3), 192-198. doi:10.1038/s41929-018-0028-2Lu, Y., Wang, J., Yu, L., Kovarik, L., Zhang, X., Hoffman, A. S., … Karim, A. M. (2018). Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl2O4 catalysts. Nature Catalysis, 2(2), 149-156. doi:10.1038/s41929-018-0192-4Zhang, B., Asakura, H., & Yan, N. (2017). Atomically Dispersed Rhodium on Self-Assembled Phosphotungstic Acid: Structural Features and Catalytic CO Oxidation Properties. Industrial & Engineering Chemistry Research, 56(13), 3578-3587. doi:10.1021/acs.iecr.7b00376Wang, H., Liu, J.-X., Allard, L. F., Lee, S., Liu, J., Li, H., … Yang, M. (2019). Surpassing the single-atom catalytic activity limit through paired Pt-O-Pt ensemble built from isolated Pt1 atoms. Nature Communications, 10(1). doi:10.1038/s41467-019-11856-9Ravel, B., & Newville, M. (2005). ATHENA,ARTEMIS,HEPHAESTUS: data analysis for X-ray absorption spectroscopy usingIFEFFIT. Journal of Synchrotron Radiation, 12(4), 537-541. doi:10.1107/s0909049505012719Perdew, J. P., Burke, K., & Ernzerhof, M. (1997). Generalized Gradient Approximation Made Simple [Phys. Rev. Lett. 77, 3865 (1996)]. Physical Review Letters, 78(7), 1396-1396. doi:10.1103/physrevlett.78.1396Grimme, S., Antony, J., Ehrlich, S., & Krieg, H. (2010). A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. The Journal of Chemical Physics, 132(15), 154104. doi:10.1063/1.3382344Kresse, G., & Furthmüller, J. (1996). Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set. Physical Review B, 54(16), 11169-11186. doi:10.1103/physrevb.54.11169Kresse, G., & Joubert, D. (1999). From ultrasoft pseudopotentials to the projector augmented-wave method. Physical Review B, 59(3), 1758-1775. doi:10.1103/physrevb.59.1758Plessow, P. N. (2018). Efficient Transition State Optimization of Periodic Structures through Automated Relaxed Potential Energy Surface Scans. Journal of Chemical Theory and Computation, 14(2), 981-990. doi:10.1021/acs.jctc.7b01070Hoffman, A. S., Debefve, L. M., Zhang, S., Perez-Aguilar, J. E., Conley, E. T., Justl, K. R., … Gates, B. C. (2018). Beating Heterogeneity of Single-Site Catalysts: MgO-Supported Iridium Complexes. ACS Catalysis, 8(4), 3489-3498. doi:10.1021/acscatal.8b00143Ren, Y., Tang, Y., Zhang, L., Liu, X., Li, L., Miao, S., … Zhang, T. (2019). Unraveling the coordination structure-performance relationship in Pt1/Fe2O3 single-atom catalyst. Nature Communications, 10(1). doi:10.1038/s41467-019-12459-0Gatla, S., Aubert, D., Agostini, G., Mathon, O., Pascarelli, S., Lunkenbein, T., … Kaper, H. (2016). Room-Temperature CO Oxidation Catalyst: Low-Temperature Metal–Support Interaction between Platinum Nanoparticles and Nanosized Ceria. ACS Catalysis, 6(9), 6151-6155. doi:10.1021/acscatal.6b00677Guan, H., Lin, J., Qiao, B., Yang, X., Li, L., Miao, S., … Zhang, T. (2016). Catalytically Active Rh Sub-Nanoclusters on TiO2 for CO Oxidation at Cryogenic Temperatures. Angewandte Chemie International Edition, 55(8), 2820-2824. doi:10.1002/anie.201510643Gaudet, J. R., de la Riva, A., Peterson, E. J., Bolin, T., & Datye, A. K. (2013). Improved Low-Temperature CO Oxidation Performance of Pd Supported on La-Stabilized Alumina. ACS Catalysis, 3(5), 846-855. doi:10.1021/cs400024uGänzler, A. M., Casapu, M., Doronkin, D. E., Maurer, F., Lott, P., Glatzel, P., … Grunwaldt, J.-D. (2019). Unravelling the Different Reaction Pathways for Low Temperature CO Oxidation on Pt/CeO2 and Pt/Al2O3 by Spatially Resolved Structure–Activity Correlations. The Journal of Physical Chemistry Letters, 10(24), 7698-7705. doi:10.1021/acs.jpclett.9b02768Nie, L., Mei, D., Xiong, H., Peng, B., Ren, Z., Hernandez, X. I. P., … Wang, Y. (2017). Activation of surface lattice oxygen in single-atom Pt/CeO 2 for low-temperature CO oxidation. Science, 358(6369), 1419-1423. doi:10.1126/science.aao2109Carrasco, J., Lopez, N., Illas, F., & Freund, H.-J. (2006). Bulk and surface oxygen vacancy formation and diffusion in single crystals, ultrathin films, and metal grown oxide structures. The Journal of Chemical Physics, 125(7), 074711. doi:10.1063/1.2335842Kropp, T., & Mavrikakis, M. (2019). Brønsted–Evans–Polanyi relation for CO oxidation on metal oxides following the Mars–van Krevelen mechanism. Journal of Catalysis, 377, 577-581. doi:10.1016/j.jcat.2019.08.002Martínez, J. I., Hansen, H. A., Rossmeisl, J., & Nørskov, J. K. (2009). Formation energies of rutile metal dioxides using density functional theory. Physical Review B, 79(4). doi:10.1103/physrevb.79.045120Soave, R., & Pacchioni, G. (2000). New bonding mode of CO on stepped MgO surfaces from density functional cluster model calculations. Chemical Physics Letters, 320(3-4), 345-351. doi:10.1016/s0009-2614(00)00246-3Sterrer, M., Risse, T., & Freund, H.-J. (2006). CO adsorption on the surface of MgO(001) thin films. Applied Catalysis A: General, 307(1), 58-61. doi:10.1016/j.apcata.2006.03.007Trionfetti, C., Babich, I. V., Seshan, K., & Lefferts, L. (2008). Presence of Lithium Ions in MgO Lattice: Surface Characterization by Infrared Spectroscopy and Reactivity towards Oxidative Conversion of Propane. Langmuir, 24(15), 8220-8228. doi:10.1021/la8006316Mihaylov, M. Y., Fierro-Gonzalez, J. C., Knözinger, H., Gates, B. C., & Hadjiivanov, K. I. (2006). Formation of Nonclassical Carbonyls of Au3+ in Zeolite NaY:  Characterization by Infrared Spectroscopy. The Journal of Physical Chemistry B, 110(15), 7695-7701. doi:10.1021/jp057426qWang, C., Bley, B., Balzer-Jöllenbeck, G., Lewis, A. R., Siu, S. C., Willner, H., & Aubke, F. (1995). New homoleptic metal carbonyl cations: the syntheses, vibrational and13C MAS NMR spectra of hexacarbonyl-ruthenium(II) and-osmium(II) undecafluorodiantimonate(V), [Ru(CO)6][Sb2F11]2and [Os(CO)6][Sb2F11]2. J. Chem. Soc., Chem. Commun., (20), 2071-2072. doi:10.1039/c39950002071Fukuda, Y., & Tanabe, K. (1973). Infrared Study of Carbon Dioxide Adsorbed on Magnesium and Calcium Oxides. Bulletin of the Chemical Society of Japan, 46(6), 1616-1619. doi:10.1246/bcsj.46.1616Philipp, R., & Fujimoto, K. (1992). FTIR spectroscopic study of carbon dioxide adsorption/desorption on magnesia/calcium oxide catalysts. The Journal of Physical Chemistry, 96(22), 9035-9038. doi:10.1021/j100201a063Busca, G., & Lorenzelli, V. (1982). Infrared spectroscopic identification of species arising from reactive adsorption of carbon oxides on metal oxide surfaces. Materials Chemistry, 7(1), 89-126. doi:10.1016/0390-6035(82)90059-1Cornu, D., Guesmi, H., Krafft, J.-M., & Lauron-Pernot, H. (2012). Lewis Acido-Basic Interactions between CO2 and MgO Surface: DFT and DRIFT Approaches. The Journal of Physical Chemistry C, 116(11), 6645-6654. doi:10.1021/jp211171

Chemical abundances of late-type pre-main sequence stars in the σ\sigma-Orionis cluster

The young $\sigma$-Orionis cluster is an important location for understanding the formation and evolution of stars, brown dwarfs, and planetary-mass objects. Its metallicity, although being a fundamental parameter, has not been well determined yet. We present the first determination of the metallicity of nine young late-type stars in $\sigma$-Orionis. Using the optical and near-infrared broadband photometry available in the literature we derive the effective temperatures for these nine cluster stars, which lie in the interval 4300--6500 K (1--3 \Msuno). These parameters are employed to compute a grid of synthetic spectra based on the code MOOG and Kurucz model atmospheres. We employ a $\chi^2$-minimization procedure to derive the stellar surface gravity and atmospheric abundances of Al, Ca, Si, Fe, Ni and Li, using multi-object optical spectroscopy taken with WYFFOS+AF2 at at the William Herschel Telescope ($\lambda/\delta\lambda\sim7500$). The average metallicity of the $\sigma$-Orionis cluster is [Fe/H] $= -0.02\pm0.09\pm0.13$ (random and systematic errors). The abundances of the other elements, except lithium, seem to be consistent with solar values. Lithium abundances are in agreement with the "cosmic" $^7$Li abundance, except for two stars which show a $\log \epsilon(\mathrm{Li})$ in the range 3.6--3.7 (although almost consistent within the error bars). There are also other two stars with $\log \epsilon(\mathrm{Li})\sim 2.75$. We derived an average radial velocity of the $\sigma$-Orionis cluster of $28\pm4$km/s. The $\sigma$-Orionis metallicity is roughly solar.Comment: Accepted for publication in Astronomy and Astrophysic

Muscle mass to visceral fat ratio is an important predictor of the metabolic syndrome in college students

This study aimed to evaluate the associations between the muscle mass to visceral fat (MVF) ratio and cardiometabolic risk factors in a large population of college students in Colombia and to propose cut-off points of this index for the metabolic syndrome (MetS). A total of 1464 young adults recruited from the FUPRECOL (Asociación de la Fuerza Prensil con Manifestaciones Tempranas de Riesgo Cardiovascular en Jóvenes y Adultos Colombianos) study were categorised into four groups based on their MVF ratio. Muscle mass and visceral fat level of the participants were measured using a bioelectrical impedance analysis. Cardiometabolic risk factors including lifestyle characteristics, anthropometry, blood pressure and biochemical parameters were assessed. The prevalence of moderate to severe obesity, hypertension and the MetS was higher in subjects in quartile (Q)1 (lower MVF ratio) (P less than 0·001). ANCOVA revealed that the subjects in Q1 had higher cardiometabolic disturbances, including altered anthropometry, blood pressure, muscle strength and biochemical parameters after adjusting for age and sex compared with young adults in higher MVF ratio quartiles (P less than 0·001). Muscular mass and physical activity levels were significantly lower in subjects with a lower MVF ratio (P less than 0·001). The receiver operating characteristic curve analyses indicated that in men the best MVF ratio cut-off point for detecting the MetS was 18·0 (AUC 0·83, sensitivity 78 % and specificity 77 %) and for women, the MVF ratio cut-off point was 13·7 (AUC 0·85, sensitivity 76 % and specificity 87 %). A lower MVF ratio is associated with a higher risk cardiometabolic profile in early adulthood, supporting that the MVF ratio could be used as a complementary screening tool that may help clinicians identify young adults at high cardiometabolic risk. © The Authors 2018