Spin and energy transfer in nanocrystals without transport of charge

We describe a mechanism of spin transfer between individual quantum dots that does not require tunneling. Incident circularly-polarized photons create inter-band excitons with non-zero electron spin in the first quantum dot. When the quantum-dot pair is properly designed, this excitation can be transferred to the neighboring dot via the Coulomb interaction with either {\it conservation} or {\it flipping} of the electron spin. The second dot can radiate circularly-polarized photons at lower energy. Selection rules for spin transfer are determined by the resonant conditions and by the strong spin-orbit interaction in the valence band of nanocrystals. Coulomb-induced energy and spin transfer in pairs and chains of dots can become very efficient under resonant conditions. The electron can preserve its spin orientation even in randomly-oriented nanocrystals.Comment: 13 pages, 3 figure

Abundances of the elements in the solar system

A review of the abundances and condensation temperatures of the elements and their nuclides in the solar nebula and in chondritic meteorites. Abundances of the elements in some neighboring stars are also discussed.Comment: 42 pages, 11 tables, 8 figures, chapter, In Landolt- B\"ornstein, New Series, Vol. VI/4B, Chap. 4.4, J.E. Tr\"umper (ed.), Berlin, Heidelberg, New York: Springer-Verlag, p. 560-63

Identification of novel and conserved microRNAs in Coffea canephora and Coffea arabica

As microRNAs (miRNAs) are important regulators of many biological processes, a series of small RNAomes from plants have been produced in the last decade. However, miRNA data from several groups of plants are still lacking, including some economically important crops. Here microRNAs from Coffea canephora leaves were profiled and 58 unique sequences belonging to 33 families were found, including two novel microRNAs that have never been described before in plants. Some of the microRNA sequences were also identified in Coffea arabica that, together with C. canephora, correspond to the two major sources of coffee production in the world. The targets of almost all miRNAs were also predicted on coffee expressed sequences. This is the first report of novel miRNAs in the genus Coffea, and also the first in the plant order Gentianales. The data obtained establishes the basis for the understanding of the complex miRNA-target network on those two important crops

Identification of novel and conserved microRNAs in Coffea canephora and Coffea arabica

As microRNAs (miRNAs) are important regulators of many biological processes, a series of small RNAomes from plants have been produced in the last decade. However, miRNA data from several groups of plants are still lacking, including some economically important crops. Here microRNAs from Coffea canephora leaves were profiled and 58 unique sequences belonging to 33 families were found, including two novel microRNAs that have never been described before in plants. Some of the microRNA sequences were also identified in Coffea arabica that, together with C. canephora, correspond to the two major sources of coffee production in the world. The targets of almost all miRNAs were also predicted on coffee expressed sequences. This is the first report of novel miRNAs in the genus Coffea, and also the first in the plant order Gentianales. The data obtained establishes the basis for the understanding of the complex miRNA-target network on those two important crops

Detection of <i>Plasmodium vivax</i> in a liver sample of a howler-monkey: one evidence more in favour of the identity between <i>Plasmodium simium</i> and <i>P. vivax</i>

ABSTRACTIntroductionThe residual malaria of Atlantic Forest systems in Brazil occurs as an endemic disease with low frequency of cases. The chronological and spatial distance among the cases indicate an absence of fitness to the classical malaria cycle. This peculiar condition raised the suspicion of a reservoir, possibly the non-human primates. Simian and human malaria occur at the same places in that region, and there is already evidence of molecular identity between the simian parasites, Plasmodium simium and Plasmodium brasilianum, and the human parasites, Plasmodium vivax and Plasmodium malariae, respectively. Two different SNPs identified in the COX1 region of the Plasmodium vivax/simium of the Atlantic Forest reinforced its characterization as a zoonotic parasite. This finding supported the development of a PCR-RFLP protocol to identify such polymorphisms, and to monitor zoonotic malaria transmission.MethodsIn the present work, we tested the above-mentioned PCR-RFLP protocol in unprecedented mosquitoes and simian samples collected in Espírito Santo State, Brazil (ES).ResultsThe parasite found in the simian sample was P. vivax, contrary to what the protocol should indicate. In the mosquito samples, the protocol disclosed both forms of the parasite.ConclusionThis result suggests that the previously published pair of SNPs, and, consequently, the PCR-RFLP protocol, are not able to distinguish the dynamics of Plasmodium spp. circulation in the Atlantic Forest endemic area of ES.</jats:sec

Nitrogen fertilization affects yield and fruit quality in pear

Mineralized nitrogen (N) from organic matter and decomposing residues in most soils are not always taken into account. Little is known about the correct N application dose for pear trees to promote yield and fruit quality, without increase the risk of N loss into the environment. The study aimed to evaluate the effect of N doses application on N soil content, tree yield and fruit quality. The treatments consisted of the application of 0, 40, 80, 120 and 160 kg N ha(-1) year(-1), whereas urea was applied on the soil surface in September and February for 5 seasons (2011/12 to 2015/16). Leaves were collected, prepared and submitted to nutrient analysis. Fruit weight, number and yield were evaluated. Soil samples were collected at 0-0.20 m for 3 seasons (2013/2014 to 2015/2016), prepared and submitted to NH4+-N and NO3-N analysis, and then mineral N content was calculated. Peel color, ethylene production, and respiration rate were analyzed in the 2015/2016 crop season after 90 days inside the controlled atmosphere storage chamber. The fruits were kept at ambient conditions for 7 days and evaluated again for peel color, ethylene production and respiration rate, as well as destructive parameters such as titratable acidity, soluble solids and pulp firmness. The doses of N application affect the fruit number and yield, but did not affect leaf nutrient concentration. The highest N levels in the soil were observed in the 2014/2015 and 2015/2016 crops. The most economical doses were 122.0, 66.4, 22.5 and 96.0 kg N ha(-1) in the crops of 2011/2012, 2012/2013, 2013/2014 and 2015/2016 respectivel