836 research outputs found
A delineating procedure to retrieve relevant publication data in research areas: the case of nanocellulose
Advances concerning publication-level classification system have been
demonstrated striking results by dealing properly with emergent, complex and interdisciplinary
research areas, such as nanotechnology and nanocellulose. However, less attention
has been paid to propose a delineating method to retrieve relevant research areas on
specific subjects. This study aims at proposing a procedure to delineate research areas
addressed in case nanocellulose. We investigate how a bibliometric analysis could provide
interesting insights into research about this sustainable nanomaterial. The research topics
clustered by a Publication-level Classification System were used. The procedure involves
an iterative process, which includes developing and cleaning a set of core publication
regarding the subject and an analysis of clusters they are associated with. Nanocellulose
was selected as the subject of study, but the methodology may be applied to any other
research area or topic. A discussion about each step of the procedure is provided. The
proposed delineation procedure enables us to retrieve relevant publications from research
areas involving nanocellulose. Seventeen research topics were mapped and associated with
current research challenges on nanocellulose.Merit, Expertise and Measuremen
Non-Supersymmetric Attractor Flow in Symmetric Spaces
We derive extremal black hole solutions for a variety of four dimensional
models which, after Kaluza-Klein reduction, admit a description in terms of 3D
gravity coupled to a sigma model with symmetric target space. The solutions are
in correspondence with certain nilpotent generators of the isometry group. In
particular, we provide the exact solution for a non-BPS black hole with generic
charges and asymptotic moduli in N=2 supergravity coupled to one vector
multiplet. Multi-centered solutions can also be generated with this technique.
It is shown that the non-supersymmetric solutions lack the intricate moduli
space of bound configurations that are typical of the supersymmetric case.Comment: 50 pages, 4 figures; v2: Reference added. To appear in JHE
Tracking Quintessence and Cold Dark Matter Candidates
We study the generation of a kination-dominated phase in the context of a
quintessential model with an inverse-power-law potential and a Hubble-induced
mass term for the quintessence field. The presence of kination is associated
with an oscillating evolution of the quintessence field and the barotropic
index. We find that, in sizeable regions of the parameter space, a tracker
scaling solution can be reached sufficiently early to alleviate the coincidence
problem. Other observational constraints originating from nucleosynthesis, the
inflationary scale, the present acceleration of the universe and the
dark-energy-density parameter can be also met. The impact of this modified
kination-dominated phase on the thermal abundance of cold dark matter
candidates is investigated too. We find that: (i) the enhancement of the relic
abundance of the WIMPs with respect to the standard paradigm, crucially depends
on the hierarchy between the freeze-out temperature and the temperature at
which the extrema in the evolution of the quintessence field are encountered,
and (ii) the relic abundance of e-WIMPs takes its present value close to the
temperature at which the earliest extremum of the evolution of the quintessence
field occurs and, as a consequence, both gravitinos and axinos arise as natural
cold dark matter candidates. In the case of unstable gravitinos, the gravitino
constraint can be satisfied for values of the initial temperature well above
those required in the standard cosmology.Comment: Final versio
Eficiência de fungos ectomicorrízicos na absorção de fósforo e na promoção do crescimento de eucalipto
The INTERFRUTA II project and the study of phytossanitary problems that affect Azorean fruit orchards and vineyards
The INTERFRUTA project is financed by the
European Commission Interreg III-B Programme and was developed for the islands of
“Madeira”, “Tenerife” and “Terceira”, for the improvement of fruit and vineyard
production in these three Atlantic regions. The project goal is a better knowledge of the
phytossanitary problems that affect apples, bananas, chestnut and vineyards, applying
methods that will contribute to solutions based on the survey of key pests, diseases and
beneficial organisms. In the three fruit crops and vineyards analyzed, the methodology
used was mainly direct observation of predefined parts of each plant (such as leaves and
flowers) on which pests might be expected to occur. The key pest C. capitata was
monitored as adults using sexual lures in a net of traps around the island of “Terceira”
up to 200 meters altitude. The beneficial insect survey was conducted using the beating
technique. For diseases, a direct sampling was carried out by the observation of 10 %
of the plants in each orchard or vineyard plot looking for visible symptoms. In apples
and vineyards, flowers and branches were collected and tested for microorganisms using
serologic and molecular techniques (Elisa and PCR). In banana plantations, the most
damaging pests were banana weevil, thrips and a fungi complex that causes symptoms
similar to Fusarium wilt. In chestnut, the pest that causes the most severe damage,
affecting around 40 % of the nuts produced, is the Chestnut tortrix, but there were some
difficulties in identifying which of the three known species was present in the Azores
islands. In vineyards, diseases that are most frequent and important include grapevine
downy mildew, powdery mildew and Botrytis. Invertebrate pests included grape
leafhoppers, thrips and eriophyid mites. The European vine moth was also surveyed but
none were found and is still not present. In apple orchards the most important problems
were thrips, mites, oriental fruit moth and codling moth. Anarsia lineatella Zeller, the
peach twig borer, was not detected and new Eriophyid species have been recorded for
the first time in the Azores as a result of the surveys. With the information collected it
was possible to create a phytossanitary diagnostic database for the Macaronesian islands
(PROFITOMAC) on the project internet pages (www.interfruta.uac.pt), to help users to
identify problems that affect the studied cultures
Quenching of Meridional Circulation in Flux Transport Dynamo Models
Guided by the recent observational result that the meridional circulation of
the Sun becomes weaker at the time of the sunspot maximum, we have included a
parametric quenching of the meridional circulation in solar dynamo models such
that the meridional circulation becomes weaker when the magnetic field at the
base of the convection zone is stronger. We find that a flux transport solar
dynamo tends to become unstable on including this quenching of meridional
circulation if the diffusivity in the convection zone is less than about 2 *
10^{11} cm^2/s. The quenching of alpha, however, has a stabilizing effect and
it is possible to stabilize a dynamo with low diffusivity with sufficiently
strong alpha-quenching. For dynamo models with high diffusivity, the quenching
of meridional circulation does not produce a large effect and the dynamo
remains stable. We present a solar-like solution from a dynamo model with
diffusivity 2.8 * 10^{12} cm^2/s in which the quenching of meridional
circulation makes the meridional circulation vary periodically with solar cycle
as observed and does not have any other significant effect on the dynamo.Comment: Consistent with the published version. Solar Physics, in pres
A Study of Cosmic Ray Secondaries Induced by the Mir Space Station Using AMS-01
The Alpha Magnetic Spectrometer (AMS-02) is a high energy particle physics
experiment that will study cosmic rays in the to range and will be installed on the International Space Station
(ISS) for at least 3 years. A first version of AMS-02, AMS-01, flew aboard the
space shuttle \emph{Discovery} from June 2 to June 12, 1998, and collected
cosmic ray triggers. Part of the \emph{Mir} space station was within the
AMS-01 field of view during the four day \emph{Mir} docking phase of this
flight. We have reconstructed an image of this part of the \emph{Mir} space
station using secondary and emissions from primary cosmic rays
interacting with \emph{Mir}. This is the first time this reconstruction was
performed in AMS-01, and it is important for understanding potential
backgrounds during the 3 year AMS-02 mission.Comment: To be submitted to NIM B Added material requested by referee. Minor
stylistic and grammer change
Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider
This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the ϒ(4S), ϒ(3S), and ϒ(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-→e+e- and (for the ϒ(4S) only) e+e-→μ+μ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-→e+e- and e+e-→μ+μ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the ϒ(3S) and ϒ(2S) resonances, an additional uncertainty arises due to ϒ→e+e-X background. For data collected off the ϒ resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the ϒ(4S), 0.58% (0.72%) for the ϒ(3S), and 0.68% (0.88%) for the ϒ(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat à l’Energie Atomique and Institut National de Physique Nucléaire et de Physiquedes Particules (France), the Bundesministerium für Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e Innovación (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)
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