11,168 research outputs found
Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP67851 c
Precision radial velocities are required to discover and characterize planets
orbiting nearby stars. Optical and near infrared spectra that exhibit many
hundreds of absorption lines can allow the m/s precision levels required for
such work. However, this means that studies have generally focused on
solar-type dwarf stars. After the main-sequence, intermediate-mass stars
(former A-F stars) expand and rotate slower than their progenitors, thus
thousands of narrow absorption lines appear in the optical region, permitting
the search for planetary Doppler signals in the data for these types of stars.
We present the discovery of two giant planets around the intermediate-mass
evolved star HIP65891 and HIP107773. The best Keplerian fit to the HIP65891 and
HIP107773 radial velocities leads to the following orbital parameters: P=1084.5
d; msin = 6.0 M; =0.13 and P=144.3 d; msin = 2.0
M; =0.09, respectively. In addition, we confirm the planetary nature
of the outer object orbiting the giant star HIP67851. The orbital parameters of
HIP67851c are: P=2131.8 d, msin = 6.0 M and =0.17. With
masses of 2.5 M and 2.4 M HIP65891 and HIP107773 are two of the
most massive stars known to host planets. Additionally, HIP67851 is one of five
giant stars that are known to host a planetary system having a close-in planet
( 0.7 AU). Based on the evolutionary states of those five stars, we
conclude that close-in planets do exist in multiple systems around subgiants
and slightly evolved giants stars, but probably they are subsequently destroyed
by the stellar envelope during the ascent of the red giant branch phase. As a
consequence, planetary systems with close-in objects are not found around
horizontal branch stars.Comment: Accepted for publication in A&
Forecasting Food Price Inflation in Developing Countries with Inflation Targeting Regimes: the Colombian Case
Many developing countries are adopting inflation targeting regimes to guide monetary policy decisions. In such countries the share of food in the consumption basket is high and policy makers often employ total inflation (as opposed to core inflation) to set inflationary targets. Therefore, central banks need to develop reliable models to forecast food inflation. Our literature review suggests that little has been done in the construction of models to forecast short-run food inflation in developing countries. We develop a model to improve short-run food inflation forecasts in Colombia. The model disaggregates food items according to economic theory and employs Flexible Least Squares given the presence of structural changes in the inflation series. We compare the performance of this new model to current models employed by the central bank. Next, we apply econometric methods to combine forecasts from alternative models and test whether such combination outperforms individual models. Our results indicate that forecasts can be improved by classifying food basket items according to unprocessed, processed and food away from home and by employing forecast combination techniques.Food Inflation, Time Series,
Public sector reform and the state of performance management in Portugal: is there a gap between performance measurement and its use?
Purpose â This paper analyses the state of performance management in the Portuguese public sector as part of the efforts towards public administration reform.
Design/methodology/approach â Theoretically, we took Bouckaert and Halliganâs (2008, pp. 35-39) approach into consideration to analyse the adoption of performance management practices. This approach was supplemented by an adaptation of Pollitt and Bouckaertâs (2011, p. 33) framework to analyse the context for administrative reforms. The used data analysis techniques include documentary analysis (namely legislation and evaluation reports of reform efforts), secondary data analysis and a survey conducted with 296 Portuguese top public managers.
Findings â Findings show that Portuguese public sector organizations adopted several tools to measure performance over the years, but failed to incorporate performance information into their management practices or to properly use it for either internal or external purposes. Concerning the ideal types proposed by Bouckaert and Halligan (2008, p. 36), Portugal is considered to fit the âPerformance Administrationâ ideal type, even though it is moving closer to the âManagements of Performanceâ ideal type.
Originality â This is one of the first comprehensive studies on the state of performance management in Portugal framed within the broader context of public sector reforms. The findings will be of interest both to scholars that study public administration reforms and performance management and to Portuguese policymakers and public managers who are interested in understanding and improving the way performance information is measured, incorporated and used in that sector.publishe
Isolamento de bactĂ©rias associadas Ă palma e prospecção do potencial de solubilizar fosfato e fixar nitrogĂȘnio.
BactĂ©rias associadas Ă s cactĂĄceas, adaptadas ao estresse hĂdrico e a altas temperaturas, podem ser usadas como inoculantes visando aumento de produtividade e recuperação de solos em processos de desertificação. Nesse sentido, visou-se selecionar bactĂ©rias endofĂticas e rizobactĂ©rias de palma (Opuntia ficus-indica) quanto aos atributos de fixar N2 e solubilizar fosfato. Sessenta e nove linhagens de bactĂ©rias, isoladas em meio livre de nitrogĂȘnio (meio NFb) foram avaliadas quanto Ă presença dos genes nifH e nifD e Ă capacidade de solubilizar fosfato. Ficou evidenciado a presença do gene nifH em dez bactĂ©rias, sendo os gĂȘneros identificados como Citrobacter, Sphingomonas, Ochrobactrum, Rodococcus, Stenotrophomonas e Enterobacter. Vinte dos isolados bacterianos avaliados foram capazes de solubilizar in vitro fosfato de rocha, sobressaindo-se o gĂȘnero Bacillus como hiperprodutor. As espĂ©cies B. megaterium e Enterobacter agglomerans apresentaram os maiores nĂveis de solubilização de fosfato. Estas bactĂ©rias, aliadas a outras caracterĂsticas benĂ©ficas, podem ser usadas para inoculação de plĂąntulas de cacto visando assegurar maior Ăndice de desenvolvimento em solos com dĂ©ficit hĂdrico
Wave localization in strongly nonlinear Hertzian chains with mass defect
We investigate the dynamical response of a mass defect in a one-dimensional
non-loaded horizontal chain of identical spheres which interact via the
nonlinear Hertz potential. Our experiments show that the interaction of a
solitary wave with a light intruder excites localized mode. In agreement with
dimensional analysis, we find that the frequency of localized oscillations
exceeds the incident wave frequency spectrum and nonlinearly depends on the
size of the intruder and on the incident wave strength. The absence of tensile
stress between grains allows some gaps to open, which in turn induce a
significant enhancement of the oscillations amplitude. We performed numerical
simulations that precisely describe our observations without any adjusting
parameters.Comment: 4 pages, 5 figures, submitted for publicatio
Desenvolvimento de caracteres da panĂcula e frutificação de duas populaçÔes de cajueiros comum e anĂŁo-precoce (A. occidentale).
Apesar de sua importancia, sao escassas as informacoes sobre a biologia floral do cajueiro no Brasil. Em 1974-75 avaliaram-se, em Pacajus, CE, dez plantas de cajueiro-comum e dez de anao-precoce. Em cada uma foram avaliadas 28 paniculas por ponto cardeal; dezesseis colhidas aos 30, 45, 60 e 75 dias e as outras dize observadas diretamente nas plantas. Em cada panicula tomaram-se o comprimento, o numero de ramificacoes, de botoes florais, de flores masculinas e hermafroditas, a duracao do florescimento e o numero de frutos jovens e colhidos. Nas paniculas estufadas em laboratorio foram estimados a media e o intervalo de confianca por epoca de coleta, dentro e entre cada ano de observacao e, nas avaliadas em campo, as medias anuais para cada carater avaliado. Em ambos os casos aplicou-se o teste t a 5% de probabilidade. Os principais resultados foram os seguintes: o cajueiro-anao-precoce na media da maioria dos caracteres avaliados; as duas populacoes apresentaram baixo indice de flores hermafroditas (<10%); as paniculas com 30 e 45 dias exibiram maior numero de flores que as mais velhas; paniculas com 40 dias ja atingiram o comprimento normal pois nao diferiram estatisticamente daquelas com outras idades; a maior concentracao de flores hermafroditas ocorreu aos 45 e 75 dias, respectivamente, para os tipos anao-precoce e comum; a maior concentracao de flores masculinas ocorreu aos 45 e 60 dias, nos dois tipos de cajueiro; o periodo medio de florescimento, nos dois anos, foi de 97,8 dias para o anao-precoce e 102,2...bitstream/item/34967/1/Bp-008.pd
Bioprospecção de actinobactérias da rizosfera para produção de metabólitos bioativos.
ActinobactĂ©rias rizosfĂ©ricas, tĂȘm mostrado grande potencial na produção de metabĂłlitos bioativos, sendo o gĂȘnero das Streptomyces o mais bem estudado e com melhor potencial para produção destes compostos. Assim, o presente trabalho visou realizar a bioprospecção de actinobactĂ©rias rizosfĂ©ricas e avaliar o potencial de seus metabĂłlitos bioativos no controle de bactĂ©rias patogĂȘnicas. Foram isoladas linhagens de actinobactĂ©rias de plantas sadias de milho, cultivado em diferentes regiĂ”es edafoclimĂĄticas do Estado de SĂŁo Paulo. As linhagens foram avaliadas quanto ao potencial de controle de Bacillus megaterium, Escherichia coli, Klebsiella spp., Pseudomonnas aeruginosa e Sthaphylococcus aureus. Os isolados que se mostraram eficientes em testes de antagonismo foram utilizados em ensaios de antibiose para verificação do potencial do composto bioativo no controle destes patĂłgenos. Foram isolados 60 actinobactĂ©rias, identificadas morfologicamente como sendo do gĂȘnero Streptomyces. Dentre estas, 31 inibiram pelo menos 1 dos 5 patĂłgenos em testes de antagonismos. Nos ensaios de antibiose, foi verificada a eficiĂȘncia dos metabĂłlitos de 25 actinobactĂ©rias no controle dos patĂłgenos testados
An eccentric companion at the edge of the brown dwarf desert orbiting the 2.4 Msun giant star HIP67537
We report the discovery of a substellar companion around the giant star
HIP67537. Based on precision radial velocity measurements from CHIRON and FEROS
high-resolution spectroscopic data, we derived the following orbital elements
for HIP67537: msin = 11.1 M,
= 4.9 AU and = 0.59. Considering
random inclination angles, this object has 65% probability to be
above the theoretical deuterium-burning limit, thus it is one of the few known
objects in the planet to brown-dwarf transition region. In addition, we
analyzed the Hipparcos astrometric data of this star, from which we derived a
minimum inclination angle for the companion of 2 deg. This value
corresponds to an upper mass limit of 0.3 M, therefore the
probability that HIP67537 is stellar in nature is 7%. The large
mass of the host star and the high orbital eccentricity makes HIP67537 a
very interesting and rare substellar object. This is the second candidate
companion in the brown dwarf desert detected in the sample of intermediate-mass
stars targeted by the EXPRESS radial velocity program, which corresponds to a
detection fraction of = 1.6%. This value is larger than the
fraction observed in solar-type stars, providing new observational evidence of
an enhanced formation efficiency of massive substellar companions in massive
disks. Finally, we speculate about different formation channels for this
object.Comment: Accepted for publication to A&
Portuguese Adaptation of Students Engagement in Schools International Scale (SESIS)
The importance of studentâs engagement has been recently pointed out in research. However, there has been a lack of engagement assessment instrument, pertaining psychometric qualities. Objective: This paper presents the Portuguese adaptation of the âStudentâs Engagement in School International Scaleâ (SESIS), drawn up from a12 countries international study (Lam et al., 2012; Lam et al., in press). Method: Psychometric properties of this scale were examined with data from 685 students from different grades (6th, 7th, 9th and 10th), from both sexes, and different regions of the country. Results: Factorial analysis of the results, with varimax rotation, lead to three different factors which explain 50.88% of the variance. The scale integrates the original 33 items, and cognitive, affective and behavioural dimensions. For the external validity study, the relationship between studentâs engagement in school results and other school variables â academic performance, self-concept â was considered, and significant relations were observed, as expected. Conclusion: The data presented highlights the qualities of SESIS, as well as its usefulness for research purposes. Suggestion: It is suggested the investigation of the extension of SESISâs three-dimensionality, in future studiesKeywords: Innovation, technology, research projects, etc. [Arial 10-point, justified alignment]
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