2,115 research outputs found
Spectropolarimetry of Type II supernovae (I) Sample, observational data and interstellar polarization
We investigate polarization spectra of hydrogen-rich core-collapse supernovae
(Type~II SNe). The polarization signal from SNe contains two independent
components: intrinsic SN polarization and interstellar polarization (ISP). From
these components, we can study the SN explosion geometry and the dust
properties in their host galaxies or in the Milky Way. In this first paper,
using a new improved method, we investigate the properties of the ISP
components of 11 well-observed Type~II SNe. As a result of our analysis, we
find that 10 out of these 11 SNe showed a steady ISP component with a
polarization degree \%, while one SN was consistent with zero
ISP. As for the wavelength dependence, SN~2001dh (and possibly SN~2012aw)
showed a non-Milky-Way-like ISP likely originating from the interstellar dust
in their respective host galaxies: their polarization maxima were located at
short wavelengths (~\AA). Similar results have been obtained
previously for highly reddened SNe. The majority of the SNe in our sample had
too large uncertainties in the wavelength dependence of their ISP components to
consider them further. Our work demonstrates that, by applying this method to a
larger SN sample, further investigation of the ISP component of the SN
polarization can provide new opportunities to study interstellar dust
properties in external galaxies.Comment: 35 pages, 36 figures, accepted for publication in A&
Higher-dimensional multifractal value sets for conformal infinite graph directed Markov systems
We give a description of the level sets in the higher dimensional
multifractal formalism for infinite conformal graph directed Markov systems. If
these systems possess a certain degree of regularity this description is
complete in the sense that we identify all values with non-empty level sets and
determine their Hausdorff dimension. This result is also partially new for the
finite alphabet case.Comment: 20 pages, 1 figur
Cascaded exciton emission of an individual strain-induced quantum dot
Single strain-induced quantum dots are isolated for optical experiments by
selective removal of the inducing InP islands from the sample surface.
Unpolarized emission of single, bi- and triexciton transitions are identified
by power-dependent photoluminescence spectroscopy. Employing time-resolved
experiments performed at different excitation powers we find a pronounced shift
of the rise and decay times of these different transitions as expected from
cascaded emission. Good agreement is found for a rate equation model for a
three step cascade
Promiscuous Honey Bee Queens Increase Colony Productivity by Suppressing Worker Selfishness
SummaryQueen monogamy is ancestral among bees, ants, and wasps (Order Hymenoptera), and the close relatedness that it generates within colonies is considered key for the evolution of eusociality in these lineages [1]. Paradoxically, queens of several eusocial species are extremely promiscuous [2], a derived behavior that decreases relatedness among workers and fitness gained from rearing siblings but benefits queens by enhancing colony productivity [3–9] and inducing workers to rear queens’ sons instead of less related worker-derived males [10–13]. Selection for promiscuity would be especially strong if productivity in a singly inseminated queen’s colony declined because selfish workers invested in personal reproduction at the expense of performing tasks that contribute to colony productivity. We show in honey bees that workers’ ovaries are more developed when queens are singly rather than multiply inseminated and that increasing ovary activation is coupled with reductions in task performance by workers and colony-wide rates of foraging and waggle-dance recruitment. Increased investment in reproductive physiology by selfish workers might result from greater incentive for them to favor worker-derived males or because low mating frequency signals a queen’s diminished quality or future fecundity. Either possibility fosters selection for queen promiscuity, revealing a novel benefit of it for eusocial insects
How large dimension guarantees a given angle?
We study the following two problems:
(1) Given and \al, how large Hausdorff dimension can a compact set
A\su\Rn have if does not contain three points that form an angle \al?
(2) Given \al and \de, how large Hausdorff dimension can a %compact
subset of a Euclidean space have if does not contain three points that
form an angle in the \de-neighborhood of \al?
An interesting phenomenon is that different angles show different behaviour
in the above problems. Apart from the clearly special extreme angles 0 and
, the angles and also play special
role in problem (2): the maximal dimension is smaller for these special angles
than for the other angles. In problem (1) the angle seems to behave
differently from other angles
Fusarium DNA levels as compared to mycotoxin levels in finnish and estonian grain samples
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Temperature and pressure-induced spin-state transitions in LaCoO3
We report the continuous variation of the spin moment of cobalt in LaCoO3
across its temperature and pressure-induced spin transitions evidenced with
K\beta emission spectra. The first thermal transition is best described by a
transition to an orbitally nondegenerate intermediate spin (S=1) state. In
parallel, continuous redistribution of the 3d electrons is also indicated by
partial fluorescence yield X-ray absorption spectra. At high pressure, our
study confirms that the material becomes low spin between 40 and 70 kbar at
room temperature
Sixty Years of Fractal Projections
Sixty years ago, John Marstrand published a paper which, among other things,
relates the Hausdorff dimension of a plane set to the dimensions of its
orthogonal projections onto lines. For many years, the paper attracted very
little attention. However, over the past 30 years, Marstrand's projection
theorems have become the prototype for many results in fractal geometry with
numerous variants and applications and they continue to motivate leading
research.Comment: Submitted to proceedings of Fractals and Stochastics
Comments on ``The first detections of the Extragalactic Background Light at 3000, 5500, and 8000 A'' by Bernstein, Freedman and Madore
A critical discussion is presented of the data analysis applied by Bernstein,
Freedman and Madore (2002 ApJ, 571, 56; and ApJ 571, 85) in their measurement
of the Extragalactic Background Light. There are questionable assumptions in
the analysis of the ground-based observations of the Zodiacal Light. The
modeling of the Diffuse Galactic Light is based on an underestimated value of
the dust column density along the line of sight. Comparison with the previously
presented results from the same observations reveals a puzzling situation: in
spite of a large difference in the atmospheric scattered light corrections the
derived Extragalactic Background Light values are exactly the same. The claim
of the paper of a ``detection of the Extragalactic Background Light'' appears
premature.Comment: 6 pages, accepted for Ap
Euclid: Searching for pair-instability supernovae with the Deep Survey
Pair-instability supernovae are theorized supernovae that have not yet been observationally confirmed. They are predicted to exist in low-metallicity environments. Because overall metallicity becomes lower at higher redshifts, deep near-infrared transient surveys probing high-redshift supernovae are suitable to discover pair-instability supernovae. The Euclid satellite, which is planned launch in 2023, has a near-infrared wide-field instrument that is suitable for a high-redshift supernova survey. The Euclid Deep Survey is planned to make regular observations of three Euclid Deep Fields (40 deg(2) in total) spanning Euclid's six-year primary mission period. While the observations of the Euclid Deep Fields are not frequent, we show that the predicted long duration of pair-instability supernovae would allow us to search for high-redshift pair-instability supernovae with the Euclid Deep Survey. Based on the current observational plan of the Euclid mission, we conduct survey simulations in order to estimate the expected numbers of pair-instability supernova discoveries. We find that up to several hundred pair-instability supernovae at z less than or similar to 3.5 can be discovered within the Euclid Deep Survey. We also show that pair-instability supernova candidates can be efficiently identified by their duration and color, which can be determined with the current Euclid Deep Survey plan. We conclude that the Euclid mission can lead to the first confirmation of pair-instability supernovae if their event rates are as high as those predicted by recent theoretical studies. We also update the expected numbers of superluminous supernova discoveries in the Euclid Deep Survey based on the latest observational plan.Peer reviewe
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