Laboratório de análise e sementes da Embrapa.Clima Temperado: 51 anos a serviço do produtor.

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Enhancing the critical current in quasiperiodic pinning arrays below and above the matching magnetic flux

Quasiperiodic pinning arrays, as recently demonstrated theoretically and experimentally using a five-fold Penrose tiling, can lead to a significant enhancement of the critical current Ic as compared to "traditional" regular pinning arrays. However, while regular arrays showed only a sharp peak in Ic(Phi) at the matching flux Phi1 and quasiperiodic arrays provided a much broader maximum at Phi<Phi1, both types of pinning arrays turned out to be inefficient for fluxes larger than Phi1. We demonstrate theoretically and experimentally the enhancement of Ic(Phi) for Phi>Phi1 by using non-Penrose quasiperiodic pinning arrays. This result is based on a qualitatively different mechanism of flux pinning by quasiperiodic pinning arrays and could be potentially useful for applications in superconducting micro-electronic devices operating in a broad range of magnetic fields.Comment: 7 pages, 4 figure

Produção de semente genética de arroz irrigado através do sistema de transplante de mudas.

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Secagem do arroz.

bitstream/CPACT-2009-09/11058/1/comunicado_145.pd

Submillimeter H2O masers in water-fountain nebulae

We report the first detection of submillimeter water maser emission toward water-fountain nebulae, which are post-AGB stars that exhibit high-velocity water masers. Using APEX we found emission in the ortho-H2O (10_29-9_36) transition at 321.226 GHz toward three sources: IRAS 15445-5449, IRAS 18043-2116 and IRAS 18286-0959. Similarly to the 22 GHz masers, the submillimeter water masers are expanding with a velocity larger than that of the OH masers, suggesting that these masers also originate in fast bipolar outflows. In IRAS 18043-2116 and IRAS 18286-0959, which figure among the sources with the fastest water masers, the velocity range of the 321 GHz masers coincides with that of the 22 GHz masers, indicating that they likely coexist. Towards IRAS 15445-5449 the submillimeter masers appear in a different velocity range, indicating that they are tracing different regions. The intensity of the submillimeter masers is comparable to that of the 22 GHz masers, implying that the kinetic temperature of the region where the masers originate should be Tk > 1000 K. We propose that the passage of two shocks through the same gas can create the conditions necessary to explain the presence of strong high-velocity 321 GHz masers coexisting with the 22 GHz masers in the same region.Comment: 4 pages, 1 figure. Accepted for publication in A&A Letter

Music@Home: a novel instrument to assess the home musical environment in the early years

The majority of children under the age of 5 appear to show spontaneous enjoyment of singing, being exposed to music and interacting with musical instruments, but whether variations in engaging in such activities in the home could contribute to developmental outcomes is still largely unknown. Critically, researchers lack a comprehensive instrument with good psychometric properties to assess the home musical environment from infancy to the preschool years. To address this gap, this paper presents two studies that describe the development and validation of the Music@Home questionnaire, which comprises two versions: Infant and Preschool. In Study 1, an initial pool of items was generated and administered to a wide audience of parents (n = 287 for the Infant, n = 347 for the Preschool version). Exploratory factor analysis was used to identify different dimensions comprising the home musical environment of both infants and pre-schoolers, and to reduce the initial pool of items to a smaller number of meaningful items. In Study 2, convergent and divergent validity and internal and test-retest reliability of the new instrument were established, using data from a different sample of participants (n = 213 for the Infant, n = 213 for the Preschool version). The second study also investigated associations between the Music@Home and musical characteristics of the parents, such as their musical education and personal engagement with music. Overall, the Music@Home constitutes a novel, valid and reliable instrument that allows for the systematic assessment of distinct aspects of the home musical environment in families with children under the age of 5. Furthermore, the Infant and Preschool versions of the Music@Home present differential associations with musical characteristics of the parents opening a new area of inquiry into how musical exposure and interaction in the home may vary across different developmental stages

A macro-realism inequality for opto-electro-mechanical systems

We show how to apply the Leggett-Garg inequality to opto-electro-mechanical systems near their quantum ground state. We find that by using a dichotomic quantum non-demolition measurement (via, e.g., an additional circuit-QED measurement device) either on the cavity or on the nanomechanical system itself, the Leggett-Garg inequality is violated. We argue that only measurements on the mechanical system itself give a truly unambigous violation of the Leggett-Garg inequality for the mechanical system. In this case, a violation of the Leggett-Garg inequality indicates physics beyond that of "macroscopic realism" is occurring in the mechanical system. Finally, we discuss the difficulties in using unbound non-dichotomic observables with the Leggett-Garg inequality.Comment: 9 pages, 2 figures. Added additional figure (2b), and associated conten

Effect of Acute Exercise on Plasma Nitric Oxide Level in Humans

Objective: Since nitric oxide (NO) plays an important role in regulating vascular tone and changes in the plasma concentration of the end product of NO (nitrite/nitrate) have been observed during exercise, we studied the influence of acute exercise on nitrite/nitrate plasma levels in a group of semiprofessional football players and in younger and older sedentary subjects. Methods: The subjects exercised for 10 min on a cycle ergometer and blood samples were obtained at rest and immediately after exercise. Plasma samples were analysed for nitrite/nitrate. Results: The acute physical exercise induced a significant increase in nitrite/nitrate plasma levels both in sedentary and in active subjects. No difference was evident between the younger and older subjects, both in the basal level and after exercise, indicating that the changes could not be due to age. The higher basal plasma level of nitrite/nitrate observed in the active subjects compared with sedentary groups indicates that the state of physical conditioning had an effect on resting NO concentration. Conclusion: It seems that either acute exercise, even for a short time, or training can induce an increase in circulating NO

Generation and control of Greenberger-Horne-Zeilinger entanglement in superconducting circuits

Going beyond the entanglement of microscopic objects (such as photons, spins, and ions), here we propose an efficient approach to produce and control the quantum entanglement of three macroscopic coupled superconducting qubits. By conditionally rotating, one by one, selected Josephson charge qubits, we show that their Greenberger-Horne-Zeilinger (GHZ) entangled states can be deterministically generated. The existence of GHZ correlations between these qubits could be experimentally demonstrated by effective single-qubit operations followed by high-fidelity single-shot readouts. The possibility of using the prepared GHZ correlations to test the macroscopic conflict between the noncommutativity of quantum mechanics and the commutativity of classical physics is also discussed.Comment: 4 Pages with 1 figure. to appear in Physical Review Letter