ABSTRACT
We update the main physical and orbital properties of the transiting hot Saturn planet HAT-P-19 b, based on a global modelling of high-precision transit and occultation light curves, taken ...with ground-based and space telescopes, archive spectra and radial velocity measurements, brightness values from broad-band photometry, and Gaia parallax. We collected 65 light curves by amateur and professional observers, measured mid-transit times, and analysed their differences from calculated transit timings based on reference ephemeris information, which we update as a result. We have not found any periodicity in the residuals of a linear trend, which we attribute to the accumulation of uncertainties in the reference mid-transit time and the orbital period. We comment on the scenarios describing the formation and migration of this hot-Saturn type exoplanet with a bloated atmosphere yet a small core, although it is orbiting a metal-rich (Fe/H = 0.24 dex) host star. Finally, we review the planetary mass–radius, the orbital period–radius, and density, and the stellar metallicity–core mass diagrams, based on the parameters we derive for HAT-P-19 b and those of the other 70 transiting Saturn-mass planets from the NASA Exoplanet Archive.
The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey of transiting planets orbiting bright stars for over 10 years. The KELT images have a pixel scale of ...∼23″ pixel−1-very similar to that of NASA's Transiting Exoplanet Survey Satellite (TESS)-as well as a large point-spread function, and the KELT reduction pipeline uses a weighted photometric aperture with radius 3′. At this angular scale, multiple stars are typically blended in the photometric apertures. In order to identify false positives and confirm transiting exoplanets, we have assembled a follow-up network (KELT-FUN) to conduct imaging with spatial resolution, cadence, and photometric precision higher than the KELT telescopes, as well as spectroscopic observations of the candidate host stars. The KELT-FUN team has followed-up over 1600 planet candidates since 2011, resulting in more than 20 planet discoveries. Excluding ∼450 false alarms of non-astrophysical origin (i.e., instrumental noise or systematics), we present an all-sky catalog of the 1128 bright stars (6 < V < 13) that show transit-like features in the KELT light curves, but which were subsequently determined to be astrophysical false positives (FPs) after photometric and/or spectroscopic follow-up observations. The KELT-FUN team continues to pursue KELT and other planet candidates and will eventually follow up certain classes of TESS candidates. The KELT FP catalog will help minimize the duplication of follow-up observations by current and future transit surveys such as TESS.
Thermally actuated shape-memory polymers (SMPs) are capable of being programmed into a temporary shape and then recovering their permanent reference shape upon exposure to heat, which facilitates a ...phase transition that allows dramatic increase in molecular mobility. Experimental, analytical, and computational studies have established empirical relations of the thermomechanical behavior of SMPs that have been instrumental in device design. However, the underlying mechanisms of the recovery behavior and dependence on polymer microstructure remain to be fully understood for copolymer systems. This presents an opportunity for bottom-up studies through molecular modeling; however, the limited time-scales of atomistic simulations prohibit the study of key performance metrics pertaining to recovery. In order to elucidate the effects of phase fraction, recovery temperature, and deformation temperature on shape recovery, here we investigate the shape-memory behavior in a copolymer model with coarse-grained potentials using a two-phase molecular model that reproduces physical crosslinking. Our simulation protocol allows observation of upwards of 90% strain recovery in some cases, at time-scales that are on the order of the timescale of the relevant relaxation mechanism (stress relaxation in the unentangled soft-phase). Partial disintegration of the glassy phase during mechanical deformation is found to contribute to irrecoverable strain. Temperature dependence of the recovery indicates nearly full elastic recovery above the trigger temperature, which is near the glass-transition temperature of the rubbery switching matrix. We find that the trigger temperature is also directly correlated with the deformation temperature, indicating that deformation temperature influences the recovery temperatures required to obtain a given amount of shape recovery, until the plateau regions overlap above the transition region. Increasing the fraction of glassy phase results in higher strain recovery at low to intermediate temperatures, a widening of the transition region, and an eventual crossover at high temperatures. Our results corroborate experimental findings on shape-memory behavior and provide new insight into factors governing deformation recovery that can be leveraged in biomaterials design. The established computational methodology can be extended in straightforward ways to investigate the effects of monomer chemistry, low-molecular-weight solvents, physical and chemical crosslinking, different phase-separation morphologies, and more complicated mechanical deformation toward predictive modeling capabilities for stimuli-responsive polymers.
Coppice management results in profound differences in forest structure and composition, which in turn can modify habitat value for bird species. We measured bird species richness and composition at ...50 sample plots in pure oak forest stands in northwestern Turkey, which differed in age, cover and height in association with coppice management. We recorded a total of 38 bird species and 699 individuals across all stands. Regression-based multimodel inference showed that structural features of forest stands strongly affect bird diversity and abundance. While canopy cover and tree height affect bird diversity positively, elevation of sampling plots, tree density and tree diameter at breast height (DBH) had a negative effect. In addition, constrained ordination analyses revealed that canopy cover was the most important factor influencing bird species composition. Forest stands that have 42-85% canopy cover, i.e., a few (2009-2580 oak trees) large tall (13.36-15.78 m) trees, were the most preferred habitat by bird species. However, we also found that different bird species favor different stand structural features. Thus, variation in stand structure from maintaining some coppice management across the landscape may be beneficial for rare or endangered species and result in greater landscape level biodiversity.
Insect reproduction may be affected by a number of factors including seasonal changes in larval or adult nutrition. The effect of season on the reproductive potential of Monochamus galloprovincialis ...(Olivier) females reared in Pinus sylvestris L. (Scots pine) logs was investigated by constructing fertility tables for each log that differed only in the season they were cut Population parameters were compared among three seasonal cohorts. The intrinsic rate of increase and most of the associated population parameters of beetles that emerged from logs cut during spring were higher than for beetles emerged from summer and autumn logs. Slight differences were found between summer and autumn cohorts. We suggest that seasonal differences in the nutritional quality of logs caused differences in M. galloprovincialis survival and reproductive potential.
Monochamus galloprovincialis (Olivier) is the vector of the pinewood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle, in Europe and Asia. Reproduction is probably the most important ...event in the life history of insects and may be affected by a number of factors, such as seasonal changes in larval or adult nutrition. In this study the effect of season on the reproductive potential of M. galloprovincialis females reared in black pine logs was investigated by constructing fertility tables for each of 43 pine logs that differed only in the season that they were cut. Population parameters were compared among 3 seasonal cohorts. The intrinsic rate of increase and related population parameters of the beetles that emerged from autumn logs were mostly higher than for beetles that emerged from spring and summer logs. These results suggest that seasonal differences in the nutritional quality of the logs (for immature development) and pine twigs (for adult feeding) may have caused the observed differences in M. galloprovincialis survival and reproduction.
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