Orbital structure of the GJ876 extrasolar planetary system, based on the latest Keck and HARPS radial velocity data

We use full available array of radial velocity data, including recently published HARPS and Keck observatory sets, to characterize the orbital configuration of the planetary system orbiting GJ876. First, we propose and describe in detail a fast method to fit perturbed orbital configuration, based on the integration of the sensitivity equations inferred by the equations of the original $N$-body problem. Further, we find that it is unsatisfactory to treat the available radial velocity data for GJ876 in the traditional white noise model, because the actual noise appears autocorrelated (and demonstrates non-white frequency spectrum). The time scale of this correlation is about a few days, and the contribution of the correlated noise is about 2 m/s (i.e., similar to the level of internal errors in the Keck data). We propose a variation of the maximum-likelihood algorithm to estimate the orbital configuration of the system, taking into account the red noise effects. We show, in particular, that the non-zero orbital eccentricity of the innermost planet \emph{d}, obtained in previous studies, is likely a result of misinterpreted red noise in the data. In addition to offsets in some orbital parameters, the red noise also makes the fit uncertainties systematically underestimated (while they are treated in the traditional white noise model). Also, we show that the orbital eccentricity of the outermost planet is actually ill-determined, although bounded by $\sim 0.2$. Finally, we investigate possible orbital non-coplanarity of the system, and limit the mutual inclination between the planets \emph{b} and \emph{c} orbits by $5^\circ-15^\circ$, depending on the angular position of the mutual orbital nodes.Comment: 36 pages, 11 figures, 3 tables; Accepted to Celestial Mechanics and Dynamical Astronom

Estimations of orbital parameters of exoplanets from transit photometry by using dynamical constraints

The probability of the detection of Earth-like exoplanets may increase in the near future after the launch of the space missions using the transit photometry as observation method. By using this technique only the semi-major axis of the detected planet can be determined, and there will be no information on the upper limit of its orbital eccentricity. However, the orbital eccentricity is a very important parameter, not only from a dynamical point of view, since it gives also information on the climate and the habitability of the Earth-like planets. In this paper a possible procedure is suggested for confining the eccentricity of an exoplanet discovered by transit photometry if an already known giant planet orbits also in the system.Comment: 16 pages, 10 figures, accepted for Cel. Mech. Dyn. Astro

Constraints on extra dimensions from precision molecular spectroscopy

9 págs.; 2 figs.; 2 tabs.; Open Access funded by Creative Commons Atribution Licence 3.0Accurate investigations of quantum-level energies in molecular systems are shown to provide a testing ground to constrain the size of compactified extra dimensions. This is made possible by recent progress in precision metrology with ultrastable lasers on energy levels in neutral molecular hydrogen (H2, HD, and D2) and molecular hydrogen ions (H2+, HD+, and D2+). Comparisons between experiment and quantum electrodynamics calculations for these molecular systems can be interpreted in terms of probing large extra dimensions, under which conditions gravity will become much stronger. Molecules are a probe of spacetime geometry at typical distances where chemical bonds are effective (i.e., at length scales of an Å). Constraints on compactification radii for extra dimensions are derived within the Arkani-Hamed-Dimopoulos-Dvali framework, while constraints for curvature or brane separation are derived within the Randall-Sundrum framework. Based on the molecular spectroscopy of D2 molecules and HD+ ions, the compactification size for seven extra dimensions (in connection to M-theory defined in 11 dimensions) of equal size is shown to be limited to R7 < 0.6 mμ . While limits on compactification sizes of extra dimensions based on other branches of physics are compared, the prospect of further tightening constraints from the molecular method is discussed. © 2015 IOP Publishing Ltd and Deutsche Physikalische GesellschaftThis work was supported by the Netherlands Foundation for Fundamental Research of Matter (FOM) through the program ‘Broken Mirrors & Drifting Constants’. B Gato-Rivera and A N Schellekens have been partially supported by funding from the Spanish Ministerio de Economia y Competitividad, Research Project FIS2012- 38816, and by the Project CONSOLIDER-INGENIO 2010, Programme CPAN (CSD2007-00042).Peer Reviewe

Nanosieves Fabricated By Interference Lithography And Electroforming

Self-sustaining Nickel membranes with periodic and regular distribution of pores, in the scale of hundred of nanometers, were produced by interference lithography and electroplating. The process consists in the recording of submicrometric 2D periodic photoresist columns, on a metal-coated glass substrate, using the double exposure of an interference fringe pattern. As the photoresist is a good electrical isolator, when the sample is immersed in a Ni electroplating bath, the array of photoresist columns impedes the Nickel deposition in the patterned areas. A nickel film is then growth among the photoresist columns with a thickness up to 80 % of the height of the columns. In order to release the submicrometric membrane from the substrate, a thick hexagonal Nickel sustaining structure is electroformed, using conventional photolithography. The dimensions of the sustaining structure can be adapted in order to fulfill the pressure requirements of the filtration system. The good uniformity of the pore sizes as well as the smooth of the surface make such devices very interesting for separation of particles by size in filtration systems.6037Sard Ghayeni, S.B., Beatson, P.J., Fane, A.J., Schneider, R.P., Bacterial passage through microfiltration membranes in wastewater applications (1999) J. Membr. Sci., 153, pp. 71-82(2002) Life Science CatalogueCalvo, J.I., Hernandez, A., Pradanos, P., Martinez, L., Bowen, W.R., Pore size distribution in microporous membranes, II bulk characterization of track-etched filters by air porometry and mercury prosimetry (1995) Journal of Colloid and Interface Science, 176, pp. 467-478Han, K., Xu, W., Ruiz, A., Ruchhoeft, P., Chellam, S., Fabrication and characterization of polymeric microfiltration membranes using aperture array lithography (2005) J. Membr. Sci., 249, pp. 193-206Kuiper, S., Van Wolferen, H., Van Rijn, C., Nijdam, W., Krijnem, G., Elwenspoek, M., Fabrication of microsieves with sub-micron pore size by laser interference lithography (2001) Journal, of Micromehcanics and Microengineering, 11, pp. 33-37Van Rijn, C.J.M., Veldhuis, G.J., Kuiper, S., Nanosieves with microsystem tecnology for microfiltration applications (1998) Nanotechnology, 9, pp. 343-345Kuiper, S., Boer, M.D., Van Rijn, C., Nijdarh, W., Krijnen, G., Elwenspoek, M., Wet and dry etching techniques for the release of sub-micrometre perforated membranes (2000) Journal of Micromechanics and Microengineering, 10, pp. 171-174Gutierrez-Rivera, L.E., De Carvalho, E.J., Suva, M.A., Cescato, L., Metallic submicrometric sieves fabricated by interferometric litography and electroforming (2005) Journal of Micromechanics and Microengineering, 15, pp. 1932-1937Griffiths, S.K., Nilson, R.H., Hruby, J.M., (1996) Modeling Electrodeposition for LIGA Microdevice Fabrication, , http://www.ca.sandia.gov/liga/process_archives.html, Sandia National Laboratories, Livermore, CaliforniaFrejlich, J., Cescato, L., Mendes, G.F., Analysis of an active stabilization system for an holographic setup (1998) Appl. Opt., 27, pp. 1967-1976Zaidi, H.S., Brueck, S.R.J., Multiple-exposure interferometric lithography (1993) J. Vac. Sci. Technol. B, 11, pp. 658-666Mello, B.A., Costa, I.F., Lima, C.R.A., Cescato, L., Developed profile of holographically exposed photoresist gratings (1995) Applied Optics, 34, pp. 597-603Mack, C.A., Development of positive photoresists (1987) J. Electrochem. Soc., 134, pp. 148-152Spiro, P., (1971) Electroforming: A Comprehensive Survey of Theory, Practice and Commercial Applications2th Edition, , Robert Draper LTDKuiper, S., Van Rijn, C.J., Nijdam, W., Elwenspoek, M.C., Development and applications of very high flux microfiltration membranes (1998) Journal of Membrane Science, 150, pp. 1-8www.mediacy.co

Bounds on the number and size of extra dimensions from molecular spectroscopy

Presentación de 30 diapositivas; 70th International Symposium on Molecular Spectroscopy (ISMS), University of Illinois at Urbana−Champaign, June 22 to 26, 2015Peer Reviewe

Stability of retained austenite in martensitic high carbon steels:Part II: Mechanical stability

The mechanical stability of retained austenite is explored in martensitic bearing steels under cyclic compressive stresses up to ∼106 cycles at 3GPa, combining X-ray diffraction and repetitive push testing. Finite element analysis and hardness testing were adopted to interpret the stress distribution across the specimen, and the stress-strain response was revealed. Austenite decomposition was observed for all samples regardless of the difference in their chemical composition and volume percentage. The decomposition is partial and a significant amount of austenite could be retained even after ∼106 stress cycles. A scenario revealing different stages of retained austenite behaviour under compressive stresses has been established. It is observed that retained austenite first decomposes during the first tens of cycles and at 103 cycles, whilst it remains stable at cycles ranging 102–103 and after 104. More importantly, results show the potential TRIP effect of retained austenite decomposition on dynamic hardening of bearing steels

Stability of retained austenite in martensitic high carbon steels:Part I: Thermal stability

Thermal stability of retained austenite in 1C-1.5Cr steels with two Si and Mn contents is studied. Time-resolved high resolution synchrotron X-ray radiation and dilatometry are employed. The threshold transformation temperatures, decomposition kinetics, associated transformation strain, as well as the influence of Si and Mn were investigated. The coefficients of linear thermal expansion for both the bulk materials and individual phases are also obtained. The results indicate that an increase in the Mn and Si contents show little influence on the onset of retained austenite decomposition, but result in more thermally stable austenite. The decomposition is accompanied by a simultaneous increase in ferrite content which causes an expansive strain in the order of 10 − 4 , and subsequent cementite development from 300 − 350 ° C which causes a contraction that helps to neutralise the expansive strain. During decomposition, a continuous increase in the carbon content of austenite, and a reduction in that of the tempered-martensite/ferrite phase was observed. This process continued at elevated temperatures until full decomposition was reached, which could take less than an hour at a heating rate of 0.05 ° C /s. Additionally, the observation of austenite peak splitting on samples with high Mn and Si contents suggests the existence of austenite of different stabilities in such matrix

The relationship between 100Cr6 steelmaking, inclusion microstructure and rolling contact fatigue performance

A processing-microstructure-performance approach is followed to study three bearing steel samples manufactured from the most frequently used continuous casting routes. The inclusion microstructures of the samples were altered by varying the metallurgy and hot working conditions. Inclusion size distribution information is obtained, showing the steel-making route that results in the highest cleanliness. 3D analysis of inclusion morphologies using electrolytic extraction indicates the irregularities on the surface to be favourable sites for crack nucleation under RCF. Flat-washer and ball-on-rod tests were conducted to study the rolling contact fatigue life of the steels, with the results from the flat-washer testing method being more representative for bearing life. This research suggests that early fatigue of bearings is governed by silicate fragmentation and late fatigue by TiN inclusions

On the complete classification of the unitary N=2 minimal superconformal field theories

Aiming at a complete classification of unitary N=2 minimal models (where the assumption of space-time supersymmetry has been dropped), it is shown that each modular invariant candidate of a partition function for such a theory is indeed the partition function of a minimal model. A family of models constructed via orbifoldings of either the diagonal model or of the space-time supersymmetric exceptional models demonstrates that there exists a unitary N=2 minimal model for every one of the allowed partition functions in the list obtained from Gannon's work. Kreuzer and Schellekens' conjecture that all simple current invariants can be obtained as orbifolds of the diagonal model, even when the extra assumption of higher-genus modular invariance is dropped, is confirmed in the case of the unitary N=2 minimal models by simple counting arguments.Comment: 53 pages; Latex; minor changes in v2: intro expanded, references added, typos corrected, footnote added on p31; renumbering of sections; main theorem reformulated for clarity, but contents unchanged. Minor revisions in v3: typos corrected, footnotes 5, 6 added, lemma 1 and section 3.3.2 rewritten for greater generality, section 3.3 review removed. To appear in Comm. Math. Phy