122 research outputs found
GeMprospector—online design of cross-species genetic marker candidates in legumes and grasses
The web program GeMprospector (URL: ) allows users to automatically design large sets of cross-species genetic marker candidates targeting either legumes or grasses. The user uploads a collection of ESTs from one or more legume or grass species, and they are compared with a database of clusters of homologous EST and genomic sequences from other legumes or grasses, respectively. Multiple sequence alignments between submitted ESTs and their homologues in the appropriate database form the basis of automated PCR primer design in conserved exons such that each primer set amplifies an intron. The only user input is a collection of ESTs, not necessarily from more than one species, and GeMprospector can boost the potential of such an EST collection by combining it with a large database to produce cross-species genetic marker candidates for legumes or grasses
Oscillations in the Sun with SONG: Setting the scale for asteroseismic investigations
Context. We present the first high-cadence multi-wavelength radial-velocity
observations of the Sun-as-a-star, carried out during 57 consecutive days using
the stellar \'echelle spectrograph at the Hertzsprung SONG Telescope operating
at the Teide Observatory. Aims. The aim was to produce a high-quality data set
and reference values for the global helioseismic parameters {\nu_{max}}, and
{\Delta \nu} of the solar p-modes using the SONG instrument. The obtained data
set or the inferred values should then be used when the scaling relations are
applied to other stars showing solar-like oscillations which are observed with
SONG or similar instruments. Methods. We used different approaches to analyse
the power spectrum of the time series to determine {\nu_{max}}; simple Gaussian
fitting and heavy smoothing of the power spectrum. {\Delta\nu} was determined
using the method of autocorrelation of the power spectrum. The amplitude per
radial mode was determined using the method described in Kjeldsen et al.
(2008). Results. We found the following values for the solar oscillations using
the SONG spectrograph: {\nu_{max}} = 3141 {\pm} 12 {\mu}Hz, {\Delta\nu} =
134.98 {\pm} 0.04 {\mu}Hz and an average amplitude of the strongest radial
modes of 16.6 {\pm} 0.4 cm/s. These values are consistent with previous
measurements with other techniques.Comment: 5 pages, 5 figures, letter accepted for A&
The mass and age of the first SONG target: the red giant 46 LMi
Context. The Stellar Observation Network Group (SONG) is an initiative to build a worldwide network of 1m telescopes with high-precision radial-velocity spectrographs. Here we analyse the first radial-velocity time series of a red-giant star measured by the SONG
telescope at Tenerife. The asteroseismic results demonstrate a major increase in the achievable precision of the parameters for red-giant
stars obtainable from ground-based observations. Reliable tests of the validity of these results are needed, however, before the accuracy
of the parameters can be trusted.
Aims. We analyse the first SONG time series for the star 46 LMi, which has a precise parallax and an angular diameter measured from interferometry, and therefore a good determination of the stellar radius. We use asteroseismic scaling relations to obtain an accurate mass, and modelling to determine the age.
Methods. A 55-day time series of high-resolution, high S/N spectra were obtained with the first SONG telescope. We derive the asteroseismic parameters by analysing the power spectrum. To give a best guess on the large separation of modes in the power spectrum, we have applied a new method which uses the scaling of Kepler red-giant stars to 46 LMi.
Results. Several methods have been applied: classical estimates, seismic methods using the observed time series, and model calculations to derive the fundamental parameters of 46 LMi. Parameters determined using the different methods are consistent within the uncertainties. We find the following values for the mass M (scaling), radius R (classical), age (modelling), and surface gravity (combining mass and radius): M = 1.09 ± 0.04 M⊙, R = 7.95 ± 0.11 R⊙ age t = 8.2 ± 1.9 Gy, and log g = 2.674 ± 0.013.
Conclusions. The exciting possibilities for ground-based asteroseismology of solar-like oscillations with a fully robotic network have been illustrated with the results obtained from just a single site of the SONG network. The window function is still a severe problem which will be solved when there are more nodes in the network
Suppression of inhomogeneous broadening in rf spectroscopy of optically trapped atoms
We present a novel method for reducing the inhomogeneous frequency broadening
in the hyperfine splitting of the ground state of optically trapped atoms. This
reduction is achieved by the addition of a weak light field, spatially
mode-matched with the trapping field and whose frequency is tuned in-between
the two hyperfine levels. We experimentally demonstrate the new scheme with Rb
85 atoms, and report a 50-fold narrowing of the rf spectrum
Oligomerization engineering of the fluorinase enzyme leads to an active trimer that supports synthesis of fluorometabolites in vitro
This work was funded by The Novo Nordisk Foundation grant to the Center for Biosustainability (NNF10CC1016517). P.I.N. was funded by grants from The Novo Nordisk Foundation (NNF20CC0035580, and LiFe, NNF18OC0034818), the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 814418 (SinFonia) and the Danish Council for Independent Research (SWEET, DFF-Research Project 8021-00039B). T.K. and M.N.D. were funded by fellowships from the European Union's Horizon 2020 research and innovation program under a Marie Skłodowska Curie project under grant agreement No. 713683 (COFUNDfellowsDTU).The fluorinase enzyme represents the only biological mechanism capable of forming stable C–F bonds characterized in nature thus far, offering a biotechnological route to the biosynthesis of value-added organofluorines. The fluorinase is known to operate in a hexameric form, but the consequence(s) of the oligomerization status on the enzyme activity and its catalytic properties remain largely unknown. In this work, this aspect was explored by rationally engineering trimeric fluorinase variants that retained the same catalytic rate as the wild-type enzyme. These results ruled out hexamerization as a requisite for the fluorination activity. The Michaelis constant (KM) for S-adenosyl-l-methionine, one of the substrates of the fluorinase, increased by two orders of magnitude upon hexamer disruption. Such a shift in S-adenosyl-l-methionine affinity points to a long-range effect of hexamerization on substrate binding – likely decreasing substrate dissociation and release from the active site. A practical application of trimeric fluorinase is illustrated by establishing in vitro fluorometabolite synthesis in a bacterial cell-free system.Publisher PDFPeer reviewe
Process evaluation for stressor reduction interventions in sport
Stressor reduction interventions may have the potential to improve the well-being of those involved in sport. Organizational psychologists have used these primary interventions in various performance domains. The authors describe the stressor reduction design and implementation processes, and the contexts in which they occur, that impact on these interventions. The authors then examine how process evaluation methods can be applied during stressor reduction in sport settings. Process evaluation requires the frequent collection of data about intervention experiences and events from multiple sources using a mixed-methods approach. The article contains practical recommendations for sport psychologists who implement stressor reduction interventions
Precise radial velocities of giant stars XIII. A second Jupiter orbiting in 4:3 resonance in the 7 CMa system
We report the discovery of a second planet orbiting the K giant star 7 CMa
based on 166 high-precision radial velocities obtained with Lick, HARPS, UCLES
and SONG. The periodogram analysis reveals two periodic signals of
approximately 745 and 980 d, associated to planetary companions. A
double-Keplerian orbital fit of the data reveals two Jupiter-like planets with
minimum masses and , orbiting at semi-major axes of
and , respectively. Given the small orbital
separation and the large minimum masses of the planets close encounters may
occur within the time baseline of the observations, thus, a more accurate
N-body dynamical modeling of the available data is performed. The dynamical
best-fit solution leads to collision of the planets and we explore the
long-term stable configuration of the system in a Bayesian framework,
confirming that 13% of the posterior samples are stable for at least 10 Myr.
The result from the stability analysis indicates that the two-planets are
trapped in a low-eccentricity 4:3 mean-motion resonance. This is only the third
discovered system to be inside a 4:3 resonance, making it very valuable for
planet formation and orbital evolution models.Comment: Accepted in A&
Aldebaran b's temperate past uncovered in planet search data
The nearby red giant Aldebaran is known to host a gas giant planetary
companion from decades of ground-based spectroscopic radial velocity
measurements. Using Gaussian Process-based Continuous Auto-Regressive Moving
Average (CARMA) models, we show that these historic data also contain evidence
of acoustic oscillations in the star itself, and verify this result with
further dedicated ground-based spectroscopy and space-based photometry with the
Kepler Space Telescope. From the frequency of these oscillations we determine
the mass of Aldebaran to be , and note that this
implies its planet will have been subject to insolation comparable to the Earth
for some of the star's main sequence lifetime. Our approach to sparse,
irregularly sampled time series astronomical observations has the potential to
unlock asteroseismic measurements for thousands of stars in archival data, and
push to lower-mass planets around red giant stars.Comment: 24 pages, 7 figures (including appendices); submitted to ApJL; paper
text, figures, data, and code at https://github.com/farr/Aldebara
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