A tunable rf SQUID manipulated as flux and phase qubit

We report on two different manipulation procedures of a tunable rf SQUID. First, we operate this system as a flux qubit, where the coherent evolution between the two flux states is induced by a rapid change of the energy potential, turning it from a double well into a single well. The measured coherent Larmor-like oscillation of the retrapping probability in one of the wells has a frequency ranging from 6 to 20 GHz, with a theoretically expected upper limit of 40 GHz. Furthermore, here we also report a manipulation of the same device as a phase qubit. In the phase regime, the manipulation of the energy states is realized by applying a resonant microwave drive. In spite of the conceptual difference between these two manipulation procedures, the measured decay times of Larmor oscillation and microwave-driven Rabi oscillation are rather similar. Due to the higher frequency of the Larmor oscillations, the microwave-free qubit manipulation allows for much faster coherent operations.Comment: Proceedings of Nobel Symposium "Qubits for future quantum computers", Goeteborg, Sweden, May 25-28, 2009; to appear in Physica Script

Deep-well ultrafast manipulation of a SQUID flux qubit

Superconducting devices based on the Josephson effect are effectively used for the implementation of qubits and quantum gates. The manipulation of superconducting qubits is generally performed by using microwave pulses with frequencies from 5 to 15 GHz, obtaining a typical operating clock from 100MHz to 1GHz. A manipulation based on simple pulses in the absence of microwaves is also possible. In our system a magnetic flux pulse modifies the potential of a double SQUID qubit from a symmetric double well to a single deep well condition. By using this scheme with a Nb/AlOx/Nb system we obtained coherent oscillations with sub-nanosecond period (tunable from 50ps to 200ps), very fast with respect to other manipulating procedures, and with a coherence time up to 10ns, of the order of what obtained with similar devices and technologies but using microwave manipulation. We introduce the ultrafast manipulation presenting experimental results, new issues related to this approach (such as the use of a feedback procedure for cancelling the effect of "slow" fluctuations), and open perspectives, such as the possible use of RSFQ logic for the qubit control.Comment: 9 pages, 7 figure

INCIDÊNCIA FÚNGICA EM GLOMÉRULOS E SÂMARAS DE Casuarina equisetifolia (CASUARINACEAE)

The casuarina (Casuarina equisetifolia) is an angiosperm belonging to the family Casuarinaceae and is widely used in the establishment of dunes on the seafront, as windbreaks in orchards and in the recovery of degraded areas. However, it has presented problems with seedling mortality in nursery. Samaras can carry microorganisms on their surface or internally, constituting one of the main means of dissemination of plant pathogens. The objective of this study was to identify and evaluate the incidence of fungi associated with glomeruli and casuarina samaras. For this, we collected glomeruli and chambers from parent trees in Santa Maria-RS. In the laboratory, the glomeruli underwent a disinfestation process and were submitted to the filter paper sanity test. The samaras were also submitted to the same test, but comparing with and without asepsis. The experimental design was completely randomized and each treatment consisted of four replicates of 25 (glomeruli/samaras). Fusarium spp., Rhizoctonia spp., Alternaria spp., Pestalotiopsis spp., Phoma spp. and Colletotrichum spp. were found in both glomeruli and samaras, possibly indicating transmission from one to another. These fungi are known worldwide for causing diseases in seeds, seedlings and seedlings in nurseries of many forest species.A casuarina (Casuarina equisetifolia) é uma angiosperma que pertence à família Casuarinaceae e é largamente utilizada na fixação de dunas na orla marítima, como quebra-ventos em pomares e na recuperação de áreas degradadas. Entretanto, tem apresentado problemas com mortalidade de plântulas em viveiro. As sâmaras podem carregar microrganismos na sua superfície ou internamente, constituindo-se um dos principais meios de disseminação de patógenos de plantas. O presente trabalho teve por objetivo identificar e avaliar a incidência de fungos associados aos glomérulos e sâmaras de casuarina. Para isso, foram coletados glomérulos e sâmaras de árvores matrizes em Santa Maria–RS. No laboratório, os glomérulos passaram por um processo de desinfestação e foram submetidos ao teste de sanidade em papel filtro. As sâmaras também foram submetidas ao mesmo teste, porém comparando-as com e sem assepsia. O delineamento experimental foi o inteiramente casualizado e cada tratamento foi composto de quatro repetições de 25 (glomérulo/sâmara). Fusarium spp., Rhizoctonia spp., Alternaria spp., Pestalotiopsis spp., Phoma spp. e Colletotrichum spp. foram encontrados tanto em glomérulos como em sâmaras, indicando, possivelmente, a transmissão de um para outro. Esses fungos são conhecidos mundialmente por causarem doenças em sementes, plântulas e mudas em viveiro de muitas espécies florestais

Morphology, dynamics and plasma parameters of plumes and inter-plume regions in solar coronal holes

Coronal plumes, which extend from solar coronal holes (CH) into the high corona and - possibly - into the solar wind (SW), can now continuously be studied with modern telescopes and spectrometers on spacecraft, in addition to investigations from the ground, in particular, during total eclipses. Despite the large amount of data available on these prominent features and related phenomena, many questions remained unanswered as to their generation and relative contributions to the high-speed streams emanating from CHs. An understanding of the processes of plume formation and evolution requires a better knowledge of the physical conditions at the base of CHs, in plumes and in the surrounding inter-plume regions (IPR). More specifically, information is needed on the magnetic field configuration, the electron densities and temperatures, effective ion temperatures, non-thermal motions, plume cross-sections relative to the size of a CH, the plasma bulk speeds, as well as any plume signatures in the SW. In spring 2007, the authors proposed a study on "Structure and dynamics of coronal plumes and inter-plume regions in solar coronal holes" to the International Space Science Institute (ISSI) in Bern to clarify some of these aspects by considering relevant observations and the extensive literature. This review summarizes the results and conclusions of the study. Stereoscopic observations allowed us to include three-dimensional reconstructions of plumes. Multi-instrument investigations carried out during several campaigns led to progress in some areas, such as plasma densities, temperatures, plume structure and the relation to other solar phenomena, but not all questions could be answered concerning the details of plume generation process(es) and interaction with the SW.Comment: To appear on: The Astronomy and Astrophysics Review. 72 pages, 30 figure

Mancha-foliar-marrom da Nogueirapecã: Identificação e Manejo da Doença nos Pomares do Sul do Brasil.

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Circulating endothelial progenitor cells from patients with renal cell carcinoma display aberrant VEGF regulation, reduced apoptosis and altered ultrastructure

Endothelial colony forming cells (ECFCs) are the only endothelial progenitor cells (EPCs) subtype belonging to the endothelial phenotype and capable of forming neovessels in vivo. We have recently shown that the intracellular Ca2+ machinery plays a key role in ECFC activation and is remodeled in ECFCs isolated from patients suffering from renal cellular carcinoma (RCC-ECFCs). More specifically, ECFCs upregulate the store-operated Ca2+ entry (SOCE) machinery, while they seemingly show a reduction in the Ca2+ concentration within the endoplasmic reticulum ([Ca2+]ER). Metastatic RCC patients are commonly treated with an anti-vascular endothelial growth factor (VEGF) therapy, but they show either intrinsic or adaptive refractoriness, which ultimately leads to their death. Herein, we assessed whether and how the rearrangement of the Ca2+ machinery impacts on the pro-angiogenic Ca2+ response to VEGF, which stimulates normal ECFCs (N-ECFCs) through an oscillatory Ca2+ response. We found that VEGF stimulates the nuclear translocation of p65/RelA, a major component of the Ca2+-dependent transcription fac- tor NF-kB, in N-ECFCs. This process is blocked by the pharmacological abrogation of VEGF-induced Ca2+ oscillations. We further showed that NF-kB controls VEGF-induced protein expression of E-selectin, VCAM-1 and MMP9. Likewise, VEGF-induced expression was also inhibited by the pharmacological suppression of the accompanying Ca2+ spikes. Thus, VEGF induces a Ca2+-dependent, NF-kB-mediated protein expression in N-ECFCs. VEGF did not trigger protein expression in RCC-ECFCs despite the fact that VEGFR-2 was normally expressed and auto-phosphorylated. Our subsequent studies employed the tar- geted recombinant Ca2+-sensitive photoprotein aequorin to confirm that [Ca2+]ER is lower in RCC-ECFCs; surprisingly, electron microscopy analysis revealed that the endoplasmic reticulum cisternae are enlarged rather than shrinked in these cells. These results show for the first time that VEGF fails to stimulate tumor-derived ECFCs: these findings could therefore help to understand the relative failure of anti-VEGF treatment in RCC patients. Reference