8,316 research outputs found
Orbital and physical properties of planets and their hosts: new insights on planet formation and evolution
We explore the relations between physical and orbital properties of planets
and properties of their host stars to identify the main observable signatures
of the formation and evolution processes of planetary systems. We use a large
sample of FGK dwarf planet hosts with stellar parameters derived in a
homogeneous way from the SWEET-Cat database to study the relation between
stellar metallicity and position of planets in the period-mass diagram. In the
second part we use all the RV-detected planets orbiting FGK stars to explore
the role of planet-disk and planet-planet interaction on the evolution of
orbital properties of planets with masses above 1MJup. We show that planets
orbiting metal-poor stars have longer periods than those in metal-rich systems.
This trend is valid for masses at least from 10MEarth to 4MJup. Earth-like
planets orbiting metal-rich stars always show shorter periods (fewer than 20
days) than those orbiting metal-poor stars. We also found statistically
significant evidence that very high mass giants have on average more eccentric
orbits than giant planets with lower mass.Finally, we show that the
eccentricity of planets with masses higher than 4MJup tends to be lower for
planets with shorter periods. Our results suggest that the planets in the P-MP
diagram are evolving differently because of a mechanism that operates over a
wide range of planetary masses. This mechanism is stronger or weaker depending
on the metallicity of the respective system. One possibility is that planets in
metal-poor disks form farther out from their central star and/or they form
later and do not have time to migrate as far as the planets in metal-rich
systems. The trends and dependencies obtained for very high mass planetary
systems suggest that planet-disk interaction is a very important and
orbit-shaping mechanism for planets in the high-mass domain. Shortened.Comment: 8 pages, 4 figures and 1 table. Accepted for publication in A&
Organizaçção laboratorial: Boas práticas de laboratório (BPL) na Embrapa Agrobiologia.
Sistema de qualidade. Objetivo do credenciamento em BPL. Escopo da norma. Campos de aplicação. Definições. Ações gerais. Organização e pessoal da unidade operacional (responsabilidades). Unidade de garantia de qualidade. Unidades operacionais. Equipamentos, materiais e reagentes. Substância-teste e substância de referência. Procedimentos operaconais padrão (POP). Execução dos estudos. Relatório final e arquivamento de registros e material.bitstream/CNPAB-2010/32964/1/doc197.pd
The HARPS search for southern extra-solar planets. XXVII. Up to seven planets orbiting HD 10180: probing the architecture of low-mass planetary systems
Context. Low-mass extrasolar planets are presently being discovered at an
increased pace by radial velocity and transit surveys, opening a new window on
planetary systems. Aims. We are conducting a high-precision radial velocity
survey with the HARPS spectrograph which aims at characterizing the population
of ice giants and super-Earths around nearby solar-type stars. This will lead
to a better understanding of their formation and evolution, and yield a global
picture of planetary systems from gas giants down to telluric planets. Methods.
Progress has been possible in this field thanks in particular to the sub-m/s
radial velocity precision achieved by HARPS. We present here new high-quality
measurements from this instrument. Results. We report the discovery of a
planetary system comprising at least five Neptune-like planets with minimum
masses ranging from 12 to 25 M_Earth, orbiting the solar-type star HD 10180 at
separations between 0.06 and 1.4 AU. A sixth radial velocity signal is present
at a longer period, probably due to a 65-M_Earth object. Moreover, another body
with a minimum mass as low as 1.4 M_Earth may be present at 0.02 AU from the
star. This is the most populated exoplanetary system known to date. The planets
are in a dense but still well-separated configuration, with significant secular
interactions. Some of the orbital period ratios are fairly close to integer or
half-integer values, but the system does not exhibit any mean-motion
resonances. General relativity effects and tidal dissipation play an important
role to stabilize the innermost planet and the system as a whole. Numerical
integrations show long-term dynamical stability provided true masses are within
a factor ~3 from minimum masses. We further note that several low-mass
planetary systems exhibit a rather "packed" orbital architecture with little or
no space left for additional planets. (Abridged)Comment: 20 pages, 15 figures, accepted for publication in A&
Manejo de plantas adultas de Digitaria insularis (capim-amargoso).
Objetivou-se estudar o manejo de plantas adultas de Digitaria insularis, supostamente resistentes, por herbicidas pulverizados em pós-emergência, assim como, a combinação de métodos (químico e mecânico) no controle
Controle químico de diferentes populações de Digitaria insularis (capim-amargoso).
Com o objetivo de estudar o controle de doze populações de Digitaria insularis pelo herbicida glyphosate isolado (1,44 e 2,16 kg ha-1) e em mistura (1,44 e 2,16 kg ha-1) com quizalofop-p-tefuryl (0,12 kg ha-1), além de agrupar as populações quanto à sensibilidade (sensível, medianamente sensível e tolerante) ao glyphosate, foi desenvolvido experimento em vasos mantidos em condições ambiente
THE EUROPEAN PROJECT "VERSUS+ / HERITAGE FOR PEOPLE". OBJECTIVES AND METHODOLOGY
Abstract. The project "VerSus+ / Heritage for PEOPLE", founded by the European Commission as part of the Creative Europe Culture Programme (Ref. 607593-CREA-1-2019-1-ES-CULT-COOP1) during the period 2019–2023, focuses on the transmission of knowledge to all branches of society and the general public. Its aim is to raise awareness on what constitutes the basis for the conservation of the tangible and intangible heritage as well as for a more sustainable contemporary architecture. This in-depth transmission of the lessons from vernacular heritage to future society is to be carried out in specific defined contexts, such as islands and archipelagos (geographically limited territories that are accessible to collaborators and administrative, technical and social agents), where vernacular heritage is under pressure, subjected to the transformations of contemporary life, particularly mass tourism. These pilot experiences should serve as a real testing ground for the implementation of actions for social participation, dissemination, education, communication, and promotion in different contexts and through different media. This project aims to reach out to society in order to showcase the sustainable qualities of the examples identified, through the establishment of an operative approach that can be adjusted to different contexts. The experiences on each island are expected to have repercussions throughout the region and, in turn, throughout the country in question, improving the perspectives and opportunities starting from best practices, and promoting the development of local skills. In addition, promotion and support from partners and associate partners will allow these experiences to be applied in other similar European and international contexts
Clinical, cytogenetic and molecular findings of a “de novo” inv dup del (6q)
Introduction: Complex rearrangements resulting in inverted duplications contiguous to a terminal deletion (inv dup del) were first reported for the short arm of chromosome 8 in1976. Since then this type of structural anomaly has been described for an increasing number of chromosomes. In these rearrangements, the concomitant presence of a deletion and a duplication has important consequences in genotype-phenotype correlations. The authors describe the clinical findings and the cytogenetic characterization of a rare inv dup del involving the long arm of chromosome 6.
Material and methods: A girl aged 5 was referred for subtelomeric studies with the indication of psychomotor retardation, autistic features and stereotipies. Chromosome analysis with high resolution GTL-banding was performed on metaphases obtained from cultured peripheral blood lymphocytes. Molecular studies included MLPA (Kits P036 and P070, MRC-Holland), FISH with subtelomeric and whole chromosome painting probes specific for chromosome 6, and cCGH techniques.
Results: Initial MLPA studies detected a subtelomeric deletion in the long arm of chromosome 6; the subsequent karyotype revealed a structurally abnormal chromosome 6 with additional material in the end of the long arm. FISH analysis showed the deletion and demonstrated that the extra material was derived from chromosome 6; cCGH tecnhiques defined the extension and confirmed the breakpoints of the duplicated segment. Thus this rearrangement was interpreted as an inv dup del (6q). Since parental karyotypes were normal, this anomaly was considered “de novo”.
Discussion: As far as we know this is the first description of a patient presenting with a “de novo” inv dup del (6q). We compare the clinical features in this child with the previously reported cases with either an isolated terminal deletion or a duplication of distal 6q. The authors enhance the importance of the combination of high resolution banding with molecular studies in the characterization of this rare rearrangement
Duality symmetry, strong coupling expansion and universal critical amplitudes in two-dimensional \Phi^{4} field models
We show that the exact beta-function \beta(g) in the continuous 2D g\Phi^{4}
model possesses the Kramers-Wannier duality symmetry. The duality symmetry
transformation \tilde{g}=d(g) such that \beta(d(g))=d'(g)\beta(g) is
constructed and the approximate values of g^{*} computed from the duality
equation d(g^{*})=g^{*} are shown to agree with the available numerical
results. The calculation of the beta-function \beta(g) for the 2D scalar
g\Phi^{4} field theory based on the strong coupling expansion is developed and
the expansion of \beta(g) in powers of g^{-1} is obtained up to order g^{-8}.
The numerical values calculated for the renormalized coupling constant
g_{+}^{*} are in reasonable good agreement with the best modern estimates
recently obtained from the high-temperature series expansion and with those
known from the perturbative four-loop renormalization-group calculations. The
application of Cardy's theorem for calculating the renormalized isothermal
coupling constant g_{c} of the 2D Ising model and the related universal
critical amplitudes is also discussed.Comment: 16 pages, REVTeX, to be published in J.Phys.A:Math.Ge
Neutrino Democracy, Fermion Mass Hierarchies And Proton Decay From 5D SU(5)
The explanation of various observed phenomena such as large angle neutrino
oscillations, hierarchies of charged fermion masses and CKM mixings, and
apparent baryon number conservation may have a common origin. We show how this
could occur in 5D SUSY SU(5) supplemented by a flavor symmetry
and additional matter supermultiplets called 'copies'. In addition, the proton
decays into , with an estimated lifetime of order
yrs. Other decay channels include and with comparable rates. We
also expect that BRBR
CMOS X-rays microdetector based on scintillating light guides
This paper describes a pixel imaging array consisting in 400 um x 400 um photodiodes fabricated in CMOS technology. Above the photodiodes, an array of scintillating CsI:Tl crystals are placed. The scintillating crystals are encapsulated in aluminum walls forming a light path to guide the produced visible light into the photodiodes. So, the x-ray energy is first converted into visible light which is then detected by the photodiode at the end of each light guide. The scintillator is 800 um thick, absorbing almost all of 20 keV x-ray photons. Usually, the spatial resolution of the scintillating x-rays detectors is identical to the scintillator thickness. By using the light guides, the scintillator thickness can be increased, without decreasing the spatial resolution. The increase of the scintillator thickness is desirable in order to increase the x-rays absorption efficiency. Tests carried out on the system show very promising results near 20 keV.This work was supported by The Foundation of Science and Technology, Portugal, FCT-CTM/POCTI/33751/1999; Grant-BD SFRH/BD/1296/2000
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