184 research outputs found
Design and expression of a retro doublet of cecropin with enhanced activity
Novel doublet molecules of cecropin A from Drosophila melanogaster
were designed and constructed combining the regular (CECdir) with the
inverted (CECret) coding sequence of the standard CEC A1 gene resulting
in the following configurations: CECdir-CECret and CECret-CECdir. These
two recombinant molecules were generated using a three-primer driven
PCR reaction yielding composite single functional aminoacidic molecules
with the coding sequences of CECdir linked in frame with the coding
sequence of CECret and vice versa. In order to obtain these
constructions, a retropeptide DNA-coding sequence was chemically
synthesized to match the expected polarity of the newly generated
CECret sequence. Both doublet antimicrobial peptides (drAMPs) were
cloned in the T7 promoter driven expression plasmid pET27b+ and
expressed in E. coli BL21 without any fusion protein. Only the former
recombinant peptide was expressed and purified from cell extracts and
its specific activity against two different bacteria showed to be
higher than those displayed by their monomer parental counterparts
Caracterizaci\uf3n del holoparasitismo de Orobanche ramosa en tomate bajo condiciones de campo
Field studies were conducted between 1999 and 2002, in Angol, Chile
(37\ub045 ' S, 72\ub044 ' W) to determine the phenology of the
system Orobanche ramosa \u2013 tomato ( Lycopersicon esculentum
Mill.), to characterize the influence of holoparasitism on the growth
and development of the host and the productive response at three
planting dates (early, normal and delayed). The O. ramosa phenology
includes underground and aerial phases, defining a total of six
development stages: "a":: nodule; "b": nodule with initial crown roots;
"c": shoot bud already visible; "d": shoot bud and crown root
developed; "e": shoot development; and "f": shoot emerged from soil
surface. The underground phase began with the establishment of the
parasite, the first phenological event (stage "a":) being detected
between 120 to 250 degree-days (DG), and the aerial phase (stage "f":)
began when 550 DG of thermal requirements was surpassed. These phases
occurred at flowering and fruit set of the host, respectively. The mean
life cycle of the system O. ramosa - tomato was completed with 1,180 DG
or 132 days after planting (DDT). Parasitism of O. ramosa altered
morphological parameters and the distribution of dry matter in the host
before the emergence of O. ramosa, the aerial components being most
effected. It translated into important losses of production at the
planting dates, which varied between 77 and 81%. Therefore, advancing
or delaying the planting date does not constitute an efficient cultural
practice for tomato fields to escape O. ramosa parasitism.Se realizaron estudios de campo entre 1999 y 2002, en Angol, Chile
(37\ub045' lat. Sur, 72\ub044' long. Oeste) para determinar la
fenolog\ueda del complejo orobanque-tomate ( Orobanche ramosa L.-
Lycopersicon esculentum Mill.), caracterizar la influencia del
holoparasitismo en el crecimiento y desarrollo del hospedero, y la
respuesta productiva en tres \ue9pocas de plantaci\uf3n (temprana,
normal y tard\ueda). La fenolog\ueda de O. ramosa comprende una
fase subterr\ue1nea y otra a\ue9rea, defini\ue9ndose un total de
seis estados de desarrollo: "a": n\uf3dulo; "b": n\uf3dulo con
ra\uedz de escaso desarrollo; "c": aparici\uf3n de yema; "d": yema
y ra\uedz desarrollada; "e": v\ue1stago desarrollado; y "f":
v\ue1stago emergiendo sobre la superficie del suelo. La fase
subterr\ue1nea se inici\uf3 con el establecimiento del
fitopar\ue1sito, detect\ue1ndose el primer evento fenol\uf3gico
(estado "a") entre 120 a 250 d\uedas grado (DG), y la fase a\ue9rea
(estado "f") comenz\uf3 cuando se super\uf3 los 550 DG de
requerimientos t\ue9rmicos. Dichas fases coincidieron con la
floraci\uf3n y fructificaci\uf3n del hospedero, respectivamente. El
ciclo de vida promedio de O. ramosa se complet\uf3 con 1.180 DG
\uf3 132 d\uedas despu\ue9s del trasplante (DDT). El parasitismo
alter\uf3 par\ue1metros morfol\uf3gicos y distribuci\uf3n de la
materia seca en el hospedero antes de la emergencia de O. ramosa,
siendo el componente a\ue9reo (follaje) el m\ue1s afectado. Ello se
tradujo en importantes p\ue9rdidas de producci\uf3n en las
\ue9pocas de plantaci\uf3n, las que variaron entre 77 y 81%. Por lo
tanto, adelantar o retrasar la plantaci\uf3n de tomate no constituye
una pr\ue1ctica cultural eficiente para escapar al efecto del
parasitismo de O. ramosa
Observation of Three-Photon Spontaneous Parametric Down-Conversion in a Superconducting Parametric Cavity
Spontaneous parametric down-conversion (SPDC) has been a key enabling technology in exploring quantum phenomena and their applications for decades. For instance, traditional SPDC, which splits a high-energy pump photon into two lower-energy photons, is a common way to produce entangled photon pairs. Since the early realizations of SPDC, researchers have thought to generalize it to higher order, e.g., to produce entangled photon triplets. However, directly generating photon triplets through a single SPDC process has remained elusive. Here, using a flux-pumped superconducting parametric cavity, we demonstrate direct three-photon SPDC, with photon triplets generated in a single cavity mode or split between multiple modes. With strong pumping, the states can be quite bright, with flux densities exceeding 60 photons per second per hertz. The observed states are strongly non-Gaussian, which has important implications for potential applications. In the single-mode case, we observe a triangular star-shaped distribution of quadrature voltages, indicative of the long-predicted "star state." The observed state shows strong third-order correlations, as expected for a state generated by a cubic Hamiltonian. By pumping at the sum frequency of multiple modes, we observe strong three-body correlations between multiple modes, strikingly, in the absence of second-order correlations. We further analyze the third-order correlations under mode transformations by the symplectic symmetry group, showing that the observed transformation properties serve to "fingerprint" the specific cubic Hamiltonian that generates them. The observed non-Gaussian, third-order correlations represent an important step forward in quantum optics and may have a strong impact on quantum communication with microwave fields as well as continuous-variable quantum computation
Influence of novel lignocellulosic residues in a biobed biopurification system on the degradation of pesticides applied in repeatedly high doses
Background: The biobed is a simple biopurification system used to
prevent the point-source pesticide contamination that occurs at farm
level. The typical composition of the biomixture used in this system is
soil, peat and straw in volumetric proportions of 1:1:2. The principal
component is straw due to its positive effects on biological activity
and thus pesticide degradation. However, access to straw can be limited
in some regions, so it must be replaced by other more readily available
lignocellulosic residues. Results: Therefore, two alternate
lignocellulosic materials (barley husks and pine sawdust) were
evaluated as partial substitutes for straw. The degradation of a
repeatedly applied mixture of six pesticides by these alternates was
assessed. The microbial respiration and fluorescein diacetate (FDA)
hydrolysis activity were also assessed. The results showed that the
highest degradation efficiency was found in mixtures containing straw
and barley husks. Each biomixtures tested achieved a high degradation
(50 to 90%) of all the pesticides used except iprodione. Repeated
applications of pesticides resulted in a slowing of the degradation
rate of all pesticide types in all biomixtures. FDA activity and
microbial respiration were higher in the biomixtures containing barley
husks and straw compared to the mixture with pine sawdust, a result
consistent with the pesticide degradations observed. Conclusions: This
paper demonstrates that the straw in the traditional biomixture can be
partially replaced by other lignocellulosic materials to efficiently
degrade a mixture of pesticides, even when the pesticides are added in
successive applications and high concentrations
Transiting exoplanets from the CoRoT space mission: XXIX. The hot Jupiters CoRoT-30 b and CoRoT-31 b
We report the discovery as well as the orbital and physical characterizations of two new transiting giant exoplanets, CoRoT-30 b and CoRoT-31 b, with the CoRoT space telescope. Methods. We analyzed two complementary data sets: photometric transit light curves measured by CoRoT, and radial velocity curves measured by the HARPS spectrometer. To derive the absolute masses and radii of the planets, we modeled the stars from available magnitudes and spectra. Results. We find that CoRoT-30 b is a warm Jupiter on a close-to-circular 9.06-day orbit around a G3V star with a semi-major axis of about 0.08 AU. It has a radius of 1.01 \ub1 0.08 RJ, a mass of 2.90 \ub1 0.22 MJ, and therefore a mean density of 3.45 \ub1 0.65 g cm-3. The hot Jupiter CoRoT-31 b is on a close-to-circular 4.63-day orbit around a G2 IV star with a semi-major axis of about 0.05 AU. It has a radius of 1.46 \ub1 0.30 RJ, a mass of 0.84 \ub1 0.34 MJ, and therefore a mean density of 0.33 \ub1 0.18 g cm-3. Conclusions. Neither system seems to support the claim that stars hosting planets are more depleted in lithium. The radii of both planets are close to that of Jupiter, but they differ in mass; CoRoT-30 b is ten times denser than CoRoT-31 b. The core of CoRoT-30 b would weigh between 15 and 75 Earth masses, whereas relatively weak constraints favor no core for CoRoT-31 b. In terms of evolution, the characteristics of CoRoT-31 b appear to be compatible with the high-eccentricity migration scenario, which is not the case for CoRoT-30 b. The angular momentum of CoRoT-31 b is currently too low for the planet to evolve toward synchronization of its orbital revolution with stellar rotation, and the planet will slowly spiral-in while its host star becomes a red giant. CoRoT-30 b is not synchronized either: it looses angular momentum owing to stellar winds and is expected reach steady state in about 2 Gyr. CoRoT-30 and 31, as a pair, are a truly remarkable example of diversity in systems with hot Jupiters
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Connecting photometric and spectroscopic granulation signals with CHEOPS and ESPRESSO
Context. Stellar granulation generates fluctuations in photometric and spectroscopic data whose properties depend on the stellar type, composition, and evolutionary state. Characterizing granulation is key for understanding stellar atmospheres and detecting planets. Aims. We aim to detect the signatures of stellar granulation, link spectroscopic and photometric signatures of convection for main-sequence stars, and test predictions from 3D hydrodynamic models. Methods. For the first time, we observed two bright stars (Teff = 5833 and 6205 K) with high-precision observations taken simultaneously with CHEOPS and ESPRESSO. We analyzed the properties of the stellar granulation signal in each individual dataset. We compared them to Kepler observations and 3D hydrodynamic models. While isolating the granulation-induced changes by attenuating and filtering the p-mode oscillation signals, we studied the relationship between photometric and spectroscopic observables. Results. The signature of stellar granulation is detected and precisely characterized for the hotter F star in the CHEOPS and ESPRESSO observations. For the cooler G star, we obtain a clear detection in the CHEOPS dataset only. The TESS observations are blind to this stellar signal. Based on CHEOPS observations, we show that the inferred properties of stellar granulation are in agreement with both Kepler observations and hydrodynamic models. Comparing their periodograms, we observe a strong link between spectroscopic and photometric observables. Correlations of this stellar signal in the time domain (flux versus radial velocities, RV) and with specific spectroscopic observables (shape of the cross-correlation functions) are however difficult to isolate due to S/N dependent variations. Conclusions. In the context of the upcoming PLATO mission and the extreme precision RV surveys, a thorough understanding of the properties of the stellar granulation signal is needed. The CHEOPS and ESPRESSO observations pave the way for detailed analyses of this stellar process
A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system
It is commonly accepted that exoplanets with orbital periods shorter than one day, also known as ultra-short-period (USP) planets, formed further out within their natal protoplanetary disks before migrating to their current-day orbits via dynamical interactions. One of the most accepted theories suggests a violent scenario involving high-eccentricity migration followed by tidal circularization. Here we present the discovery of a four-planet system orbiting the bright (V = 10.5) K6 dwarf star TOI-500. The innermost planet is a transiting, Earth-sized USP planet with an orbital period of ~13 hours, a mass of 1.42 \ub1 0.18 Mâ, a radius of 1.166â0.058+0.061Râ and a mean density of 4.89â0.88+1.03gcmâ3. Via Doppler spectroscopy, we discovered that the system hosts 3 outer planets on nearly circular orbits with periods of 6.6, 26.2 and 61.3 days and minimum masses of 5.03 \ub1 0.41 Mâ, 33.12 \ub1 0.88 Mâ and 15.05â1.11+1.12Mâ, respectively. The presence of both a USP planet and a low-mass object on a 6.6-day orbit indicates that the architecture of this system can be explained via a scenario in which the planets started on low-eccentricity orbits then moved inwards through a quasi-static secular migration. Our numerical simulations show that this migration channel can bring TOI-500 b to its current location in 2 Gyr, starting from an initial orbit of 0.02 au. TOI-500 is the first four-planet system known to host a USP Earth analogue whose current architecture can be explained via a non-violent migration scenario
TOI-969: a late-K dwarf with a hot mini-Neptune in the desert and an eccentric cold Jupiter
Context. The current architecture of a given multi-planetary system is a key fingerprint of its past formation and dynamical evolution history. Long-term follow-up observations are key to complete their picture. Aims. In this paper, we focus on the confirmation and characterization of the components of the TOI-969 planetary system, where TESS detected a Neptune-size planet candidate in a very close-in orbit around a late K-dwarf star. Methods. We use a set of precise radial velocity observations from HARPS, PFS, and CORALIE instruments covering more than two years in combination with the TESS photometric light curve and other ground-based follow-up observations to confirm and characterize the components of this planetary system. Results. We find that TOI-969 b is a transiting close-in (Pb ⌠1.82 days) mini-Neptune planet (Formula Presented), placing it on the lower boundary of the hot-Neptune desert (Teq,b = 941 \ub1 31 K). The analysis of its internal structure shows that TOI-969 b is a volatile-rich planet, suggesting it underwent an inward migration. The radial velocity model also favors the presence of a second massive body in the system, TOI-969 c, with a long period of (Formula Presented) days, a minimum mass of (Formula Presented), and a highly eccentric orbit of (Formula Presented). Conclusions. The TOI-969 planetary system is one of the few around K-dwarfs known to have this extended configuration going from a very close-in planet to a wide-separation gaseous giant. TOI-969 b has a transmission spectroscopy metric of 93 and orbits a moderately bright (G = 11.3 mag) star, making it an excellent target for atmospheric studies. The architecture of this planetary system can also provide valuable information about migration and formation of planetary systems
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