13,527 research outputs found
Explaining Jupiter's magnetic field and equatorial jet dynamics
Spacecraft data reveal a very Earth-like Jovian magnetic field. This is
surprising since numerical simulations have shown that the vastly different
interiors of terrestrial and gas planets can strongly affect the internal
dynamo process. Here we present the first numerical dynamo that manages to
match the structure and strength of the observed magnetic field by embracing
the newest models for Jupiter's interior. Simulated dynamo action primarily
occurs in the deep high electrical conductivity region while zonal flows are
dynamically constrained to a strong equatorial jet in the outer envelope of low
conductivity. Our model reproduces the structure and strength of the observed
global magnetic field and predicts that secondary dynamo action associated to
the equatorial jet produces banded magnetic features likely observable by the
Juno mission. Secular variation in our model scales to about 2000 nT per year
and should also be observable during the one year nominal mission duration.Comment: 7 pages, 4 figures, accepted for publication in Geophysical Research
Letter
Axial gravity, massless fermions and trace anomalies
This article deals with two main topics. One is odd parity trace anomalies in
Weyl fermion theories in a 4d curved background, the second is the introduction
of axial gravity. The motivation for reconsidering the former is to clarify the
theoretical background underlying the approach and complete the calculation of
the anomaly. The reference is in particular to the difference between Weyl and
massless Majorana fermions and to the possible contributions from tadpole and
seagull terms in the Feynman diagram approach. A first, basic, result of this
paper is that a more thorough treatment, taking account of such additional
terms { and using dimensional regularization}, confirms the earlier result. The
introduction of an axial symmetric tensor besides the usual gravitational
metric is instrumental to a different derivation of the same result using Dirac
fermions, which are coupled not only to the usual metric but also to the
additional axial tensor. The action of Majorana and Weyl fermions can be
obtained in two different limits of such a general configuration. The results
obtained in this way confirm the previously obtained ones.Comment: 55 pages, comments added in section 2 and 5. Sections 6.4, 6.6, 7,
7.1, 7.2 and Appendices 5.3, 5.5 partially modifie
Potato production impacts of the association trichodorids and TRV in naturally infected fields
An investigation was conducted to determine the effect of soil-born Tobacco rattle virus (TRV) isolates on yield and some quality attributes of 8 potato cultivars (Agata, Amorosa, Almera, Cunéria, Kondor, Picasso, Raja and Stemster) in Portuguese growing areas. Preliminary results revealed that some attributes (canopy growth, total yield, tuber numbers and yield within size grades, tuber spraing symptoms and secondary growths) are severely affected in the sites with viruliferous trichodorids transmitting TRV. It was shown that TRV has real conditions for survival and cause economic impact in potato crop in these regions. These results have potential interest to all potato growing countries.Centro de Biologia Molecular e Ambiental (CBMA), UMCentre of Natural Resources, Environment and Society Studies (CERNAS), College of Agriculture of Coimbra (ESAC)Eurobatata, Comércio de Produtos Alimentares, Lda, PORTUGA
Pathway Weathering in Granitoid Rocks from Central Region of Angola: Geochemical and Mineralogical Data
The Central Region of Angola is characterized by the abundance of granitoid rocks, whose weathering “in situ” originated the so-called residual soils. The textural, geochemical and mineralogical properties of these soils depend not only on the chemical composition of parent rock, but mainly on the local climatic and geomorphological characteristics.
In the study area, sampling sites were selected, which extend from the region of Kwanza- Norte (Kassenda, Dondo) through Kwanza-Sul (Cangulo, Quibala and Waco Kungo) until the plateau of Huambo, where samples of fresh rock, weathered rock and its residual soil were collected along each weathering profile.
Chemical analytical data were determined using X-ray fluorescence (XRF) analysis of the major and minor elements, whereas mineralogical data were determined using X-ray diffraction (XRD), on the samples of rock and on the respective residual soil.
The results obtained and their comparative analysis between the sampling sites, as well as along each weathering profile is presented.
This paper allows contributing to the knowledge of the geochemical weathering in tropical areas, as is the case of Angola
Beyond onboard sensors in robotic swarms: Local collective sensing through situated communication
The constituent robots in swarm robotics systems are typically equipped with relatively simple, onboard sensors of limited quality and range. When robots have the capacity to communicate with one another, communication has so far been exclusively used for coordination. In this paper, we present a novel approach in which
local, situated communication is leveraged to overcome the sensory limitations of the individual robots. In
our approach, robots share sensory inputs with neighboring robots, thereby effectively extending each other’s
sensory capabilities. We evaluate our approach in a series of experiments in which we evolve controllers for
robots to capture mobile preys. We compare the performance of (i) swarms that use our approach, (ii) swarms
in which robots use only their limited onboard sensors, and (iii) swarms in which robots are equipped with
ideal sensors that provide extended sensory capabilities without the need for communication. Our results show
that swarms in which local communication is used to extend the sensory capabilities of the individual robots
outperform swarms in which only onboard sensors are used. Our results also show that in certain experimental
configurations, the performance of swarms using our approach is close to the performance of swarms with
ideal sensors.info:eu-repo/semantics/acceptedVersio
Avaliação da dormência em acessos precoces do bag amendoim.
Sementes de amendoim apresentam dormência em diferentes graus, sendo esta característica mais pronunciada na subespécie hypogaea e em variedades de ciclo mais longo. A dormência é interessante do ponto de visto agronômico por evitar perdas durante a colheita e por estar relacionada à menor contaminação por aflatoxinas. Trinta e três acessos, com ciclo entre 90 e 100 dias, do Banco Ativo de Germoplasma de Amendoim foram avaliados quanto à dormência das sementes 14 dias após a colheita. Vinte sementes de cada acesso, tratadas com fungicida, foram dispostas em papel germitest umedecido em incubadas a 30 oC em germinador no Laboratório de Qualidade de Sementes da Embrapa Arroz e Feijão
Performance assessment of micropollutants removal from water using advanced oxidation processes
In a global climate change scenario, reliable access to clean and safe water for all remains a great
worldwide challenge for the twenty first century, as one of the most ambitious targets of several Sustainable
Development Goals (SDG) established in the UN Agenda 2030. The increasing presence in the urban aquatic
ecosystems of priority pollutants and contaminants of emerging concerning (CECs) have brought new
challenges to the existing water treatment systems (WTS) concerning with public health protection and the of
drinking water sources preservation. Advanced oxidation processes (AOPs) have been widely studied because
of their potential as a complementary or alternative process to conventional wastewater treatment. Several
AOPs using nanomaterials as photocatalyst can be particularly effective in the degradation of many toxic
micropollutants, and enhance the multifunctionality, versatility and sustainability of WTS.
This work presents a synthesis of the major results obtained in several pilot and lab-scale studies aiming to
assess the performance of different low-cost catalytic processes used for antibiotic and pesticide removal. For
each photo-oxidation reactors, different test scenarios are defined in order to evaluate the effects of several
abiotic and hydraulic parameters on process kinetics and removal efficiencies.
The experimental results were very promising, because antibiotic removal efficiencies achieved the maximum
value of 96% for the photo-oxidation by water columns with suspended TiO2 nanoparticles, and 98% for the
photocatalytic filtration performed by a porous medium coated with TiO2. In the photoelectrocatalytic reactor,
the atrazine concentration has been fully removed for reaction times between 35 and 95 minutes.(undefined
On a generalised model for time-dependent variance with long-term memory
The ARCH process (R. F. Engle, 1982) constitutes a paradigmatic generator of
stochastic time series with time-dependent variance like it appears on a wide
broad of systems besides economics in which ARCH was born. Although the ARCH
process captures the so-called "volatility clustering" and the asymptotic
power-law probability density distribution of the random variable, it is not
capable to reproduce further statistical properties of many of these time
series such as: the strong persistence of the instantaneous variance
characterised by large values of the Hurst exponent (H > 0.8), and asymptotic
power-law decay of the absolute values self-correlation function. By means of
considering an effective return obtained from a correlation of past returns
that has a q-exponential form we are able to fix the limitations of the
original model. Moreover, this improvement can be obtained through the correct
choice of a sole additional parameter, . The assessment of its validity
and usefulness is made by mimicking daily fluctuations of SP500 financial
index.Comment: 6 pages, 4 figure
Challenges in the rabbit haemorrhagic disease 2 (RHDV2) molecular diagnosis of vaccinated rabbits
Molecular methods are fundamental tools for the diagnosis of viral infections. While interpretation of
results is straightforward for unvaccinated animals, where positivity represents ongoing or past
infections, the presence of vaccine virus in the tissues of recently vaccinated animals may mislead
diagnosis.
In this study, we investigated the interference of RHDV2 vaccination in the results of a RT-qPCR for
RHDV2 detection, and possible associations between mean Cq values of
five animal groups differing in
age, vaccination status and origin (domestic/wild).
Viral sequences from vaccinated rabbits that died of RHDV2 infection (n = 14) were compared with the
sequences from the commercial vaccines used in those animals. Group Cq means were compared through
Independent t-test and One-way ANOVA.
We proved that RHDV2 vaccine-RNA is not detected by the RT-qPCR as early as 15 days post-
vaccination, an important fact in assisting results interpretation for diagnosis.
Cq values of vaccinated and non-vaccinated infected domestic adults showed a statistically significant
difference (p
<
0.05), demonstrating that vaccination-induced immunity reduces viral loads and delays
disease progression. Contrarily, in vaccinated young rabbits higher viral loads were registered compared
to non-vaccinated kittens. No significant variation (p = 0.3824) was observed between viral loads of non-
vaccinated domestic and wild RHDV2-victimised rabbits. Although the reduced number of vaccinated
young animals analysed hampered a robust statistical analysis, this occurrence suggests that passively
acquired maternal antibodies may inhibit the active immune response to vaccination, delaying
protection and favouring disease progression.
Our
finding emphasises the importance of adapting kitten RHDV2 vaccination schedules to circumvent
this interference phenomenon
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