We report the complete genome sequence of Clostridium cadaveris IFB3C5, a strain isolated from the resected tumor of a treatment naive colorectal cancer patient. This genome is comprised of a ...singular chromosome of approximately 3.63 Mbp in length, contains two plasmids, and has an overall mean GC content of 31.7%.
We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance ...started in 2015 October, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1%-2.5% dips, named "Elsie," "Celeste," "Skara Brae," and "Angkor," which persist on timescales from several days to weeks. Our main results so far are as follows: (i) there are no apparent changes of the stellar spectrum or polarization during the dips and (ii) the multiband photometry of the dips shows differential reddening favoring non-gray extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale <1 m, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term "secular" dimming, which may be caused by independent processes, or probe different regimes of a single process.
We examined the phenological relationship between the abundance of Tetraopes tetraophthalmus (Foerster) and flowers of its host plant Asclepias syriaca and tested the hypothesis that flowers are an ...important nutritional resource relative to foliage. Over 3 yr, we found that the abundance, emergence, immigration, and emigration of beetles in natural populations were positively related to milkweed flowering on individual patches. In experiments where inflorescences were removed from sections of milkweed patches, beetles showed a strong positive response in abundance to the presence of milkweed flowers. At the individual level, the role of florivory versus feeding on foliage was equivocal. Beetles showed no preference for flowers versus foliage. Digestibility of flowers was greater than foliage, but the conversion of ingested material showed no difference for adult beetles fed flowers versus foliage. Relative and absolute differences between beetles fed flowers versus foliage varied between years. In 1996, beetles fed a diet of flowers produced significantly fewer larvae than beetles fed foliage alone, but showed no difference in lifespan. In 1997, a diet of flowers alone produced both longer lifespans and greater reproductive output than a diet of flowers and foliage. A nutritional hypothesis did not consistently explain the population level response to milkweed flowers.
Planet Hunters IX. KIC 8462852 - where's the flux? Boyajian, T S; LaCourse, D M; Rappaport, S A ...
Monthly notices of the Royal Astronomical Society,
04/2016, Letnik:
457, Številka:
4
Journal Article
Recenzirano
Over the duration of the Kepler mission, KIC 8462852 was observed to undergo irregularly shaped, aperiodic dips in flux of up to ~20 per cent. The dipping activity can last for between 5 and 80 d. We ...characterize the object with high-resolution spectroscopy, spectral energy distribution fitting, radial velocity measurements, high-resolution imaging, and Fourier analyses of the Kepler light curve. We determine that KIC 8462852 is a typical main-sequence F3 V star that exhibits no significant IR excess, and has no very close interacting companions. In this paper, we describe various scenarios to explain the dipping events observed in the Kepler light curve. We confirm that the dipping signals in the data are not caused by any instrumental or data processing artefact, and thus are astrophysical in origin. We construct scenario-independent constraints on the size and location of a body in the system that are needed to reproduce the observations. We deliberate over several assorted stellar and circumstellar astrophysical scenarios, most of which have problems explaining the data in hand. By considering the observational constraints on dust clumps in orbit around a normal main-sequence star, we conclude that the scenario most consistent with the data in hand is the passage of a family of exocomet or planetesimal fragments, all of which are associated with a single previous break-up event, possibly caused by tidal disruption or thermal processing. The minimum total mass associated with these fragments likely exceeds 10 super( -6) M..., corresponding to an original rocky body of >100 km in diameter. We discuss the necessity of future observations to help interpret the system. (ProQuest: ... denotes formulae/symbols omitted.)
Planet Hunters IX. KIC 8462852 – where's the flux? Boyajian, T. S.; LaCourse, D. M.; Rappaport, S. A. ...
Monthly notices of the Royal Astronomical Society,
04/2016, Letnik:
457, Številka:
4
Journal Article
The so-called "dipper" stars host circumstellar disks and have optical and infrared light curves that exhibit quasi-periodic or aperiodic dimming events consistent with extinction by transiting dusty ...structures orbiting in the inner disk. Most of the proposed mechanisms explaining the dips---i.e., occulting disk warps, vortices, and forming planetesimals---assume nearly edge-on viewing geometries. However, our analysis of the three known dippers with publicly available resolved sub-mm data reveals disks with a range of inclinations, most notably the face-on transition disk J1604-2130 (EPIC 204638512). This suggests that nearly edge-on viewing geometries are not a defining characteristic of the dippers and that additional models should be explored. If confirmed by further observations of more dippers, this would point to inner disk processes that regularly produce dusty structures far above the outer disk midplane in regions relevant to planet formation.
The time of occurrence of reinforced lever responses of rats depends on the characteristics of the distribution of times from food to the next available food. Two groups of 10 rats were trained, in ...counterbalanced order, on two variable-interval schedules of reinforcement that were equated for the mean, standard deviation, and range of the intervals from food to the next available food, but which differed in shape. The differences in the shape of the interfood interval distributions resulted in differences in the distribution of interfood intervals, of postreinforcement pauses, the function relating response rate to time since food, and the power spectra of times of response. Quantitative timing models, such as scalar timing theory and a multiple-oscillator model, differ in their assumptions about the nature of the internal clock and the representation of time in memory. The multiple-oscillator model and scalar timing theory accounted for different features of the data.
The properties of two massless wave equations relevant to quark bound states are examined. We establish general conditions on the Lorentz-scalar and Lorentz-vector potentials which yield arbitrary ...leading Regge trajectories for the case of circular classical motion. A semiclassical approximation which includes radial motion reproduces remarkably well the exact solutions. The conditions for a mesonic tower structure are discussed.
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