3,919 research outputs found
Arranjos e populações de plantas de milho e feijão no sistema consorciado em Sergipe.
bitstream/item/69094/1/CPATC-COM.-TEC.-02-79.pd
Andreev tunneling through a double quantum-dot system coupled to a ferromagnet and a superconductor: effects of mean field electronic correlations
We study the transport properties of a hybrid nanostructure composed of a
ferromagnet, two quantum dots, and a superconductor connected in series. By
using the non-equilibrium Green's function approach, we have calculated the
electric current, the differential conductance and the transmittance for
energies within the superconductor gap. In this regime, the mechanism of charge
transmission is the Andreev reflection, which allows for a control of the
current through the ferromagnet polarization. We have also included interdot
and intradot interactions, and have analyzed their influence through a mean
field approximation. In the presence of interactions, Coulomb blockade tend to
localized the electrons at the double-dot system, leading to an asymmetric
pattern for the density of states at the dots, and thus reducing the
transmission probability through the device. In particular, for non-zero
polarization, the intradot interaction splits the spin degeneracy, reducing the
maximum value of the current due to different spin-up and spin-down densities
of states. Negative differential conductance (NDC) appears for some regions of
the voltage bias, as a result of the interplay of the Andreev scattering with
electronic correlations. By applying a gate voltage at the dots, one can tune
the effect, changing the voltage region where this novel phenomenon appears.
This mechanism to control the current may be of importance in technological
applications.Comment: 12 pages, 11 figure
Thermal Effective Lagrangian of Static Gravitational Fields
We compute the effective Lagrangian of static gravitational fields
interacting with thermal fields. Our approach employs the usual imaginary time
formalism as well as the equivalence between the static and space-time
independent external gravitational fields. This allows to obtain a closed form
expression for the thermal effective Lagrangian in space-time dimensions.Comment: Accepted for publication in the Physical Review
Competição de cultivares de milho (Zea mays L.) no Estado de Sergipe.
bitstream/item/126642/1/Competicao-de-cultivares-de-milho.pd
VELOCITY PROFILE VISUALIZATION OF WATER NATURAL PERCOLATION IN A POROUS MEDIUM
This paper aims to show the profile and the behavior of the velocity of the water flow through a porous medium composed of clay and sand aggregated by burning in an oil furnace. The work models mathematics based on the Navier-Stokes differential equation, which represents the behavior of the water velocity flow in porous medium taking into account parameters of a low velocity laminar flow, increased load loss value and Number of Reynolds > 1. Physical phenomena such as porosity, permeability, particles arrangement, radius and wet perimeter are considered in the equation. The study shows the three-dimensional profile of the water percolation velocity which, originated from the capillary phenomenon, causes a sum of the tensions of increased values able to produce cracks in the medium structure. And, differently from filtration phenomenon, which overcomes the capillarity of the medium by the gravitational force or by efforts applied aiming to increase the flow velocity, the natural percolation opposes to the gravity and to the surrounding pressure moving slowly, reaching the flow at 30 and 40 centimeters depending on the permeability of the porous medium
Órgãos agrÃcolas em Sergipe: panorâma histórico da pesquisa.
bitstream/item/26089/1/doc-89.pd
In Adolescents With Epilepsy, High Scores Of Anxiety And Depression Are Associated With Occurrence Of Seizures In Public Places.
Objective To assess depression and anxiety symptoms of adolescents with epilepsy compared with adolescents without epilepsy. Method The study sample consisted of: case participants (50 subjects) attending the pediatric epilepsy clinic of a tertiary hospital and control participants (51 subjects) from public schools. The instruments utilized were: identification card with demographic and epilepsy data, Beck Depression Inventory and State-Trait Anxiety Inventory. Results No significant differences were founded between the groups regarding scores for depression and anxiety symptoms but both groups presented moderate scores of anxiety. A correlation was found between low scores anxiety and not frequent seizures, low scores anxiety and perception of seizure control, high scores of anxiety and depression and occurrence of seizures in public places. Conclusion Low scores of anxiety are associated with not frequent seizures; high scores of anxiety and depression are associated with occurrence of seizures in public places.73205-1
Estudo sobre o comportamento de cultivares de milho na região semi-árida do Estado de Sergipe.
bitstream/item/80184/1/CPATC-COM.-TEC.-16-84.pd
Postharvest treatments to mitigate the internal browning in "Bartlett" pears.
Internal browning is an important disorder in pear fruit which can lead to economic losses. Pears (Pyrus communis L. cv. Bartlett) were harvested at early harvest maturity of 90 N from a commercial orchard in southern Brazil. Methyl jasmonate, ethanol, and 1-methylcyclopropene vapor treatments were carried out for 24 hours in order to mitigate the internal browning disorder. Fruit were stored for up to 150 days at 0 ± 1 °C and 90 ± 5 % RH. Pears exhibited internal browning in 37 % of the control samples after 90 days of cold storage. However, no internal browning symptoms were observed in the 1-MCP treatment. The first symptoms in 1-MCP samples were noticed after 120 days of cold storage (12 %)and reached 100 % in five days at room temperature. 1-MCP-treated pears showed flesh firmness values of 82 N after 90 days of cold storage and 18.7 N when they were removed from the cold storage and kept at 20 °C. The greatest acceptance index was attributed to 1- MCP pears after 90 days at 0 ± 1 °C followed by 5 days at 20 ± 1 °C (89.35). High acceptance indexes were attributed to MeJa (77.95) and control pears (76.40) after 30 days in cold storage followed by 5 days at room temperature. 1-MCP (0.3 µL L-1 , 24 hours at 0 ± 1 °C) treatment delays ripening and mitigates the internal browning in early harvested ?Bartlett? pears, that can be stored for up to 90 days at 0 ± 1 °C
Extension of storage and quality maintenance of 'Rocha' and 'Packham's Triumph' pears using modified atmosphere packaging (Bag-It-Fresh).
'Rocha' anel 'Packham's Ttiumph ' pears were harvested in January 2011 when the fruit in, the orchard reached flesh Iirmncss values of 67.6 anel 74.7 N, respectivelyResumo S11-3
- …