Algebraic Topology of Calabi-Yau Threefolds in Toric Varieties

We compute the integral homology (including torsion), the topological K-theory, and the Hodge structure on cohomology of Calabi-Yau threefold hypersurfaces and complete intersections in Gorenstein toric Fano varieties. The methods are purely topological

The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets

Probing the connection between a star's metallicity and the presence and properties of any associated planets offers an observational link between conditions during the epoch of planet formation and mature planetary systems. We explore this connection by analyzing the metallicities of Kepler target stars and the subset of stars found to host transiting planets. After correcting for survey incompleteness, we measure planet occurrence: the number of planets per 100 stars with a given metallicity $M$. Planet occurrence correlates with metallicity for some, but not all, planet sizes and orbital periods. For warm super-Earths having $P = 10-100$ days and $R_P = 1.0-1.7~R_E$, planet occurrence is nearly constant over metallicities spanning $-$0.4 dex to +0.4 dex. We find 20 warm super-Earths per 100 stars, regardless of metallicity. In contrast, the occurrence of warm sub-Neptunes ($R_P = 1.7-4.0~R_E$) doubles over that same metallicity interval, from 20 to 40 planets per 100 stars. We model the distribution of planets as $d f \propto 10^{\beta M} d M$, where $\beta$ characterizes the strength of any metallicity correlation. This correlation steepens with decreasing orbital period and increasing planet size. For warm super-Earths $\beta = -0.3^{+0.2}_{-0.2}$, while for hot Jupiters $\beta = +3.4^{+0.9}_{-0.8}$. High metallicities in protoplanetary disks may increase the mass of the largest rocky cores or the speed at which they are assembled, enhancing the production of planets larger than 1.7 $R_E$. The association between high metallicity and short-period planets may reflect disk density profiles that facilitate the inward migration of solids or higher rates of planet-planet scattering.Comment: 32 pages, 15 figures, 9 tables, accepted for publication in The Astronomical Journa

Experience With Empirical Criteria For Rotating Stall In Radial Vaneless Diffusers.

LecturePg. 97-106A seven stage, centrifugal compressor, for gas lift service on a North Sea oil production platform, exhibited subsynchronous shaft vibrations during full load, high density, factory tests. Pressure transducers in each stage characterized two stages as stalled and traced the cause of rotor vibration to rotating stall in the diffuser of the last stage. Modifications to that diffuser of the last stage corrected the subsynchronous shaft vibration. The other stage that exhibited characteristics of diffuser rotating stall was left unchanged as it did not yield harmful subsynchronous shaft vibration. The original compressor configuration was designed to meet Senoo and Kinoshita's criterion [1, 2] for inception of rotating stall in a vaneless diffuser. However, its diffuser widths, b3, were less than the impeller tip widths, b2, while b3 and b2 widths were equal in Senoo's experiment. Kobayashi, Nishida, et al. [3], and Nishida, et al. [4], extended Senoo's criteria by accounting for a b1/b2 ratio less than one. The subject compressor was analyzed using the Kobayashi, et al. [3], criterion. Data reduction of the testing condition producing diffuser rotating stall demonstrated significant margin to the criterion. The generous shape of the inlet diffuser contour was suggested as being the source of the disparity between the criterion and the data reduction values

Ecological condition of coastal ocean waters along the U.S. Mid-Atlantic Bight: 2006

In May 2006, the NOAA National Ocean Service (NOS), in conjunction with the EPA National Health and Environmental Effects Laboratory (NHEERL), conducted an assessment of the status of ecological condition of soft-bottom habitat and overlying waters throughout the mid-Atlantic Bight (MAB) portion of the eastern U.S. continental shelf. The study area encompassed the region from Cape Cod, MA and Nantucket Shoals in the northeast to Cape Hatteras in the south, and was defined using a one nautical mile buffer of the shoreline extended seaward to the shelf break (~100-m depth contour). A total of 50 stations were targeted for sampling using standard methods and indicators applied in prior NOAA coastal studies and EPA’s Environmental Monitoring and Assessment Program (EMAP) and National Coastal Assessment (NCA). A key feature adopted from these studies was the incorporation of a random probabilistic sampling design. Such a design provides a basis for making unbiased statistical estimates of the spatial extent of ecological condition relative to various measured indicators and corresponding thresholds of concern. Indicators included multiple measures of water quality, sediment quality, and biological condition (benthic fauna). Through coordination with the NOAA Fisheries Service/Northeast Fisheries Science Center (NFS/NEFSC), samples of summer flounder (Paralichthys dentatus) also were obtained from 30 winter 2007 bottom-trawl survey stations in overlapping portions of the study area and used for analysis of chemical-contaminant body burdens

KELT-6b: A P ~ 7.9 Day Hot Saturn Transiting a Metal-poor Star with a Long-period Companion

We report the discovery of KELT-6b, a mildly inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V = 10.38 host star (BD+31 2447) is a mildly evolved, late-F star with T_(eff_ = 6102 ± 43 K,_log g_* =4.07_(-0.07)^(+0.04), and [Fe/H] = –0.28 ± 0.04, with an inferred mass M_* = 1.09 ± 0.04 M_☉ and radius R_* =1.58_(-0.09)^(+0.16) ,R_☉. The planetary companion has mass M_P = 0.43 ± 0.05 M_(Jup), radius R_p =1.19_(-0.08)^(+0.13),R_(Jup), surface gravity g_p = 2.86_(-0.08)^(+0.06), and density P_p = 0.31_(-0.08)^(+0.07), cm^(-3). The planet is on an orbit with semimajor axis ɑ = 0.079 ± 0.001 AU and eccentricity e = 0.22_(-0.10)^(+0.12), which is roughly consistent with circular, and has ephemeris of T_c(BJD_(TDB)) = 2456347.79679 ± 0.00036 and P = 7.845631 ± 0.000046 days. Equally plausible fits that employ empirical constraints on the host-star parameters rather than isochrones yield a larger planet mass and radius by ~4}-7}. KELT-6b has surface gravity and incident flux similar to HD 209458b, but orbits a host that is more metal poor than HD 209458 by ~0.3 dex. Thus, the KELT-6 system offers an opportunity to perform a comparative measurement of two similar planets in similar environments around stars of very different metallicities. The precise radial velocity data also reveal an acceleration indicative of a longer-period third body in the system, although the companion is not detected in Keck adaptive optics images

Rotating flux-focusing eddy current probe for flaw detection

A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks about circular fasteners and other circular inhomogeneities in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil, The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. By rotating the probe in a path around a circular fastener such as a rivet while maintaining a constant distance between the probe and the center of a rivet, the signal due to current flow about the rivet can be held constant. Any further changes in the current distribution, such as due to a fatigue crack at the rivet joint, can be detected as an increase in the output voltage above that due to the flow about the rivet head

Long-Period Giant Companions to Three Compact, Multiplanet Systems

Understanding the relationship between long-period giant planets and multiple smaller short-period planets is critical for formulating a complete picture of planet formation. This work characterizes three such systems. We present Kepler-65, a system with an eccentric (e = 0.28 ± 0.07) giant planet companion discovered via radial velocities (RVs) exterior to a compact, multiply transiting system of sub-Neptune planets. We also use precision RVs to improve mass and radius constraints on two other systems with similar architectures, Kepler-25 and Kepler-68. In Kepler-68 we propose a second exterior giant planet candidate. Finally, we consider the implications of these systems for planet formation models, particularly that the moderate eccentricity in Kepler-65\u27s exterior giant planet did not disrupt its inner system

The Mass of the White Dwarf Companion in the Self-Lensing Binary KOI-3278: Einstein vs. Newton

KOI-3278 is a self-lensing stellar binary consisting of a white-dwarf secondary orbiting a Sun-like primary star. Kruse and Agol (2014) noticed small periodic brightenings every 88.18 days in the Kepler photometry and interpreted these as the result of microlensing by a white dwarf with about 63$\%$ of the mass of the Sun. We obtained two sets of spectra for the primary that allowed us to derive three sets of spectroscopic estimates for its effective temperature, surface gravity, and metallicity for the first time. We used these values to update the Kruse and Agol (2014) Einsteinian microlensing model, resulting in a revised mass for the white dwarf of $0.539^{+0.022}_{-0.020} \, M_{\odot}$. The spectra also allowed us to determine radial velocities and derive orbital solutions, with good agreement between the two independent data sets. An independent Newtonian dynamical MCMC model of the combined velocities yielded a mass for the white dwarf of $0.5122^{+0.0057}_{-0.0058} \, M_{\odot}$. The nominal uncertainty for the Newtonian mass is about four times better than for the Einsteinian, $\pm 1.1\%$ vs. $\pm 4.1\%$ and the difference between the two mass determinations is $5.2 \%$. We then present a joint Einsteinian microlensing and Newtonian radial velocity model for KOI-3278, which yielded a mass for the white dwarf of $0.5250^{+0.0082}_{-0.0089} \, M_{\odot}$. This joint model does not rely on any white dwarf evolutionary models or assumptions on the white dwarf mass-radius relation. We discuss the benefits of a joint model of self-lensing binaries, and how future studies of these systems can provide insight into the mass-radius relation of white dwarfs.Comment: ApJ Accepted; 22 Pages, 8 Figures, 6 Tables and 4 Supplementary Table

The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets

The size of a planet is an observable property directly connected to the physics of its formation and evolution. We used precise radius measurements from the California-Kepler Survey (CKS) to study the size distribution of 2025 $\textit{Kepler}$ planets in fine detail. We detect a factor of $\geq$2 deficit in the occurrence rate distribution at 1.5-2.0 R$_{\oplus}$. This gap splits the population of close-in ($P$ < 100 d) small planets into two size regimes: R$_P$ < 1.5 R$_{\oplus}$ and R$_P$ = 2.0-3.0 R$_{\oplus}$, with few planets in between. Planets in these two regimes have nearly the same intrinsic frequency based on occurrence measurements that account for planet detection efficiencies. The paucity of planets between 1.5 and 2.0 R$_{\oplus}$ supports the emerging picture that close-in planets smaller than Neptune are composed of rocky cores measuring 1.5 R$_{\oplus}$ or smaller with varying amounts of low-density gas that determine their total sizes.Comment: Paper III in the California-Kepler Survey series, accepted to the Astronomical Journa

Thickness Gauging of Single-Layer Conductive Materials with Two-Point Non Linear Calibration Algorithm

A thickness gauging instrument uses a flux focusing eddy current probe and two-point nonlinear calibration algorithm. The instrument is small and portable due to the simple interpretation and operational characteristics of the probe. A nonlinear interpolation scheme incorporated into the instrument enables a user to make highly accurate thickness measurements over a fairly wide calibration range from a single side of nonferromagnetic conductive metals. The instrument is very easy to use and can be calibrated quickly