Habitability of known exoplanetary systems based on measured stellar properties

At present, because of observational selection effects, we know of no exoplanetary systems with any planetary masses close to that of the Earth. We have therefore used computer models to see whether such planets could be dynamically stable in the presence of the more massive planets known to be present, and in particular whether planets with roughly an Earth mass could remain confined to the classical habitable zone (HZ) for long enough for life to have emerged. Measured stellar properties have been used to determine for each system the present location of the HZ. We have also determined the critical distances from the orbit of each giant planet within which an Earth-mass planet would suffer large orbital changes. We then evaluated the present habitability of each and every exoplanetary system by examining the penetration of these critical distances into the HZ. The critical distances can be obtained by extensive computer modelling of an exoplanetary system. This is far too time consuming to apply to all of the 150 or so systems already known, and to keep up with the latest discoveries. Therefore, in earlier work we studied a few systems in great detail, and developed a speedier means of obtaining the critical distances. We summarize this comparatively quick method here. We can then evaluate comparatively quickly the present habitability of each exoplanetary system by examining the penetration of the critical distance(s) into the HZ. The results are encouraging for astrobiology.Comment: Accepted for publication by The Astrophysical Journal. A few revisions have been made following suggestions by the refere

Searching new targets for the control of Black Rot: following the role of host factors modulating the infection process of Phyllosticta ampelicida

Black Rot is a grapevine disease caused by the ascomycete Phyllosticta ampelicida. Neglected so far, this is developing into a pertinent problem in organic viticulture as resistant varieties are still lacking. Here, we follow cellular details of the infection process in the susceptible vinifera variety Müller-Thurgau and screen the ancestral European wild grapevine (V. vinifera sylvestris) for resistance to Black Rot. Using a standardized infection assay, we follow fungal development using LTSEM and quantify key stages on different hosts using fluorescence microscopy. There is considerable variation in susceptibility, which is associated with more rapid leaf maturation. Hyphal growth on different carbon sources shows a preference for pectins over starch, cellulose or xylans. In the resistant sylvestris genotypes Ketsch 16 and Ketsch 18 we find that neither spore attachment nor appressorium formation, but hyphal elongation is significantly inhibited as compared to Müller-Thurgau. Moreover, defence-related oxidative burst and accumulation of phenolic compounds is stimulated in the resistant genotypes. We arrive at a model, where more rapid maturation of the cell wall in these sylvestris genotypes sequesters pectins as major food source and thus block hyphal elongation. This paves the way for introgression of genetic factors responsible for cell wall maturation into V. vinifera to develop Black Rot-resistant varieties of grapevine

A New Shear Estimator for Weak Lensing Observations

We present a new shear estimator for weak lensing observations which properly accounts for the effects of a realistic point spread function (PSF). Images of faint galaxies are subject to gravitational shearing followed by smearing with the instrumental and/or atmospheric PSF. We construct a `finite resolution shear operator' which when applied to an observed image has the same effect as a gravitational shear applied prior to smearing. This operator allows one to calibrate essentially any shear estimator. We then specialize to the case of weighted second moment shear estimators. We compute the shear polarizability which gives the response of an individual galaxy's polarization to a gravitational shear. We then compute the response of the population of galaxies, and thereby construct an optimal weighting scheme for combining shear estimates from galaxies of various shapes, luminosities and sizes. We define a figure of merit --- an inverse shear variance per unit solid angle --- which characterizes the quality of image data for shear measurement. The new method is tested with simulated image data. We discuss the correction for anisotropy of the PSF and propose a new technique involving measuring shapes from images which have been convolved with a re-circularizing PSF. We draw attention to a hitherto ignored noise related bias and show how this can be analyzed and corrected for. The analysis here draws heavily on the properties of real PSF's and we include as an appendix a brief review, highlighting those aspects which are relevant for weak lensing.Comment: 39 pages, 9 figure

Intercomparison of carbonate chemistry measurements on a cruise in northwestern European shelf seas

Four carbonate system variables were measured in surface waters during a cruise aimed at investigating ocean acidification impacts traversing northwestern European shelf seas in the summer of 2011. High-resolution surface water data were collected for partial pressure of carbon dioxide (pCO2; using two independent instruments) and pH using the total pH scale (pHT), in addition to discrete measurements of total alkalinity and dissolved inorganic carbon. We thus overdetermined the carbonate system (four measured variables, two degrees of freedom), which allowed us to evaluate the level of agreement between the variables on a cruise whose main aim was not intercomparison, and thus where conditions were more representative of normal working conditions. Calculations of carbonate system variables from other measurements generally compared well with direct observations of the same variables (Pearson’s correlation coefficient always greater than or equal to 0.94; mean residuals were similar to the respective accuracies of the measurements). We therefore conclude that four of the independent data sets of carbonate chemistry variables were of high quality. A diurnal cycle with a maximum amplitude of 41 μatm was observed in the difference between the pCO2 values obtained by the two independent analytical pCO2 systems, and this was partly attributed to irregular seawater flows to the equilibrator and partly to biological activity inside the seawater supply and one of the equilibrators. We discuss how these issues can be addressed to improve carbonate chemistry data quality on future research cruises

Creation and characterization of vortex clusters in atomic Bose-Einstein condensates

We show that a moving obstacle, in the form of an elongated paddle, can create vortices that are dispersed, or induce clusters of like-signed vortices in 2D Bose-Einstein condensates. We propose new statistical measures of clustering based on Ripley's K-function which are suitable to the small size and small number of vortices in atomic condensates, which lack the huge number of length scales excited in larger classical and quantum turbulent fluid systems. The evolution and decay of clustering is analyzed using these measures. Experimentally it should prove possible to create such an obstacle by a laser beam and a moving optical mask. The theoretical techniques we present are accessible to experimentalists and extend the current methods available to induce 2D quantum turbulence in Bose-Einstein condensates.Comment: 9 pages, 9 figure

Aryldiazonium tetrafluoroborate salts as green and efficient coupling partners for the Suzuki-Miyaura reaction : from optimisation to mole scale

The use of aryldiazonium tetrafluoroborate salts as coupling partners in the Suzuki-Miyaura reaction was investigated from a process chemistry perspective including safety evaluation, solvent and catalyst screening and multi-variate factor optimization. Optimised conditions were applied to a range of substrates to evaluate the scope and limitations of the reaction and one example was carried out on mole-scale to demonstrate the practicality and scalability of the proces

Supergravity Instabilities of Non-Supersymmetric Quantum Critical Points

Motivated by the recent use of certain consistent truncations of M-theory to study condensed matter physics using holographic techniques, we study the SU(3)-invariant sector of four-dimensional, N=8 gauged supergravity and compute the complete scalar spectrum at each of the five non-trivial critical points. We demonstrate that the smaller SU(4)^- sector is equivalent to a consistent truncation studied recently by various authors and find that the critical point in this sector, which has been proposed as the ground state of a holographic superconductor, is unstable due to a family of scalars that violate the Breitenlohner-Freedman bound. We also derive the origin of this instability in eleven dimensions and comment on the generalization to other embeddings of this critical point which involve arbitrary Sasaki-Einstein seven manifolds. In the spirit of a resurging interest in consistent truncations, we present a formal treatment of the SU(3)-invariant sector as a U(1)xU(1) gauged N=2 supergravity theory coupled to one hypermultiplet.Comment: 46 page

Decoherent Neutrino Mixing, Dark Energy and Matter-Antimatter Asymmetry

A CPT violating decoherence scenario can easily account for all the experimental evidence in the neutrino sector including LSND. In this work it is argued that this framework can also accommodate the Dark Energy content of the Universe, as well as the observed matter-antimatter asymmetry.Comment: 6 pages, no figures, some typos corrected, and discussion modified below eq (3), no effects on conclusion

Sustainable Energy Storage

This Final Design Review document covers the work we, students at California Polytechnic State University – San Luis Obispo, have performed in collaboration with Mr. Harish Bhutani and Dr. Mohammad Noori. The project’s intent is to create an energy storage system for off-grid and developing region applications using alternative technologies to lithium-ion battery storage. We plan to manufacture and assemble a scale model of the energy storage system to prove effectiveness and practicality. This system will store enough energy to power basic appliances and essential devices for a house or community. The chosen design direction will be a flywheel, as it is very energy dense and is less complex than other options. The following will outline the entire design process, including the ideas we created, the design challenges, and the testing of our physical build. To meet climate change goals set around the globe, our world needs to head towards a more sustainable future, and the energy sector is no exception. This project aims to help with the research and design of this new field and present a final product that will have a meaningful impact on our world