Estresse por déficit hídrico em plantas forrageiras.

bitstream/CNPC-2010/23051/1/doc89.pd

Revealing the nature of magnetic shadows with numerical 3D-MHD simulations

We investigate the interaction of magneto-acoustic waves with magnetic network elements with the aim of finding possible signatures of the magnetic shadow phenomenon in the vicinity of network elements. We carried out three-dimensional numerical simulations of magneto-acoustic wave propagation in a model solar atmosphere that is threaded by a complexly structured magnetic field, resembling that of a typical magnetic network element and of internetwork regions. High-frequency waves of 10 mHz are excited at the bottom of the simulation domain. On their way through the upper convection zone and through the photosphere and the chromosphere they become perturbed, refracted, and converted into different mode types. We applied a standard Fourier analysis to produce oscillatory power-maps of the line-of-sight velocity. In the power maps of the upper photosphere and the lower chromosphere, we clearly see the magnetic shadow: a seam of suppressed power surrounding the magnetic network elements. We demonstrate that this shadow is linked to the mode conversion process and that power maps at these height levels show the signature of three different magneto-acoustic wave modes.Comment: Astronomy & Astrophysics Letters, in print 4 pages, 4 figure

Ligulate inflorescence of Helianthus x multiflorus, cv. Soleild’Or, correlates with a mis-regulation of a CYCLOIDEA gene characterised by insertion of a transposable element

Members of CYCLOIDEA (CYC)/TEOSINTE BRANCHED1 (TB1) transcription factor family are essential to control flower symmetry and inflorescence architecture. In the Helianthus annuus genome, ten CYC/TB1 genes have been identified. Studies performed on mutants recognised HaCYC2c as one of the key players controlling zygomorphism in sunflower. We identified CYC2c genes in the diploid Helianthus decapetalus (HdCYC2c) and in the interspecific hybrid Helianthus × multiflorus (H × mCYC2cA and H × mCYC2cB), a triploid (2n = 3× = 51), originated from unreduced eggs of H. decapetalus fertilised by reduced H. annuus male gametes. Phylogenetic analysis showed that HdCYC2c and H × mCYC2c were placed within a CYC2 subclade together with HaCYC2c but distinct from it. The present data showed that in H. × multiflorus the allele derived from H. annuus is deleted or highly modified.\ud The H. × multiflorus taxon exists as radiate and ligulate inflorescence types. We analysed CYC2c expression in H. decapetalus and in the cultivar ‘Soleil d'Or’ of H. × multiflorus, a ligulate inflorescence type with actinomorphic corolla of disk flowers transformed into a zygomorphic ray‐like corolla. In H. decapetalus, the HdCYC2c gene showed differential expression between developing flower types, being up‐regulated in the corolla of ray flowers in comparison to the disk flower corolla. In H. × multiflorus, an insertion of 865 bp, which is part of a CACTA transposable element, was found in the 5′‐untranslated region (5′‐UTR) of H × mCYC2cB. This insertion could promote, even with epigenetic mechanisms, ectopic expression of the gene throughout the inflorescence, resulting in the observed loss of actinomorphy and originating a ligulate head

Radiative transfer effects on Doppler measurements as sources of surface effects in sunspot seismology

We show that the use of Doppler shifts of Zeeman sensitive spectral lines to observe wavesn in sunspots is subject to measurement specific phase shifts arising from, (i) altered height range of spectral line formation and the propagating character of p mode waves in penumbrae, and (ii) Zeeman broadening and splitting. We also show that these phase shifts depend on wave frequencies, strengths and line of sight inclination of magnetic field, and the polarization state used for Doppler measurements. We discuss how these phase shifts could contribute to local helioseismic measurements of 'surface effects' in sunspot seismology.Comment: 12 pages, 4 figures, Accepted for publication in the Astrophysical Journal Letter

Investigation of corrosion-erosion phenomena in the primary cooling system of SPIDER

SPIDER dedicated cooling plant has to remove up to 10 MW thermal power from in-vessel components and auxiliary systems. The circuit is characterized by three main heat transfer systems: primary, secondary and tertiary systems. The primary system is made of four circuits, with only three operating so far, these are called PC01, PC02 and PC03. These three circuits respectively cool SPIDER power supplies and the beam source components using ultrapure water. During 2019 SPIDER experimental campaigns, it was observed that electrical resistivity of water degraded considerably and more quickly (∼25 MΩ cm h−1 in PC01) than estimated by design. To overcome this issue, water had to be restored very frequently to maintain the desired characteristics and avoid possible detrimental leakage currents throughout the circuit. The reason for this severe water degradation has to be better understood before issues such as abrupt failures may arise. This work presents a preliminary analysis of the two main circuits (PC01 and PC02) where an estimation of water degradation induced by general corrosion of stainless steels and copper components was made. This preliminary estimation showed that PC01 could be more prone to general corrosion than PC02; however, the rate of water conductivity increase was 5.3 times smaller than that observed during experiments in 2019 and 2020

Bias Dependence of the Depletion Layer Width in Semi-Insulating GaAs by Charge Collection Scanning Microscopy

A procedure for the evaluation of the depletion region width of a Schottky barrier diode made on semi-insulating materials has been assessed and applied to gallium arsenide nuclear detectors. This procedure, which makes use of the optical beam induced current method of charge collection scanning microscopy, allows the direct measurement of the depletion layer width. By taking into account the high resistivity of the material under examination and measuring the diode reverse current, it is possible to evaluate the actual voltage applied at the depletion layer boundaries. It was found that, at low actual bias values, the voltage dependence of the depletion layer follows the usual square root power law, while at increasing voltages, it changes into a linear behavior. An explanation in terms of deep trap effect and trap field-enhanced capture cross-section is proposed even though further work must be done to explain the space charge width dependence on bias applied in terms of the deep trap influence

Multiplexed nanoplasmonic biosensor for one-step simultaneous detection of Chlamydia trachomatis and Neisseria gonorrhoeae in urine.

Development of rapid and multiplexed diagnostic tools is a top priority to address the current epidemic problem of sexually transmitted diseases. Here we introduce a novel nanoplasmonic biosensor for simultaneous detection of the two most common bacterial infections: Chlamydia trachomatis and Neisseria gonorrhoeae. Our plasmonic microarray is composed of gold nanohole sensor arrays that exhibit the extraordinary optical transmission (EOT), providing highly sensitive analysis in a label-free configuration. The integration in a microfluidic system and the precise immobilization of specific antibodies on the individual sensor arrays allow for selective detection and quantification of the bacteria in real-time. We achieved outstanding sensitivities for direct immunoassay of urine samples, with a limit of detection of 300 colony forming units (CFU)/mL for C. trachomatis and 1500CFU/mL for N. gonorrhoeae. The multiplexing capability of our biosensor was demonstrated by analyzing different urine samples spiked with either C. trachomatis or N. gonorrhoeae, and also containing both bacteria. We could successfully detect, identify and quantify the levels of the two bacteria in a one-step assay, without the need for DNA extraction or amplification techniques. This work opens up new possibilities for the implementation of point-of-care biosensors that enable fast, simple and efficient diagnosis of sexually transmitted infections

A time-temperature integrator based on fluorescent and polymorphic compounds

Despite the variety of functional properties of molecular materials, which make them of interest for a number of technologies, their tendency to form inhomogeneous aggregates in thin films and to self-organize in polymorphs are considered drawbacks for practical applications. Here, we report on the use of polymorphic molecular fluorescent thin films as time temperature integrators, a class of devices that monitor the thermal history of a product. The device is fabricated by patterning the fluorescent model compound thieno(bis)imide-oligothiophene. The fluorescence colour of the pattern changes as a consequence of an irreversible phase variation driven by temperature, and reveals the temperature at which the pattern was exposed. The experimental results are quantitatively analysed in the range 20–200°C and interpreted considering a polymorph recrystallization in the thin film. Noteworthy, the reported method is of general validity and can be extended to every compound featuring irreversible temperature-dependent change of fluorescence

Long-Term Evaluation of Capsulotomy Shape and Posterior Capsule Opacification after Low-Energy Bimanual Femtosecond Laser-Assisted Cataract Surgery

Purpose. To evaluate capsulotomy shape and posterior capsule opacification (PCO) during an 18-month follow-up for bimanual femtosecond laser-assisted cataract surgery (FLACS). Methods. 74 eyes operated by a well-trained surgeon with bimanual FLACS technique using low-energy LDV Z8 (Ziemer Ophthalmic Systems AG, Port, Switzerland) were included in the study. The follow-up period was 18 \ub1 2 months. Another 91 eyes, which underwent standard bimanual microincision cataract surgery (B-MICS), served as a control group. In all cases, a BunnyLens AF (Hanita Lenses, Israel) intraocular lens was implanted in the bag. A digital image of the capsule with slit-lamp retroillumination was performed in all patients at 18 months of follow-up. Image analysis software (ImageJ) was used to evaluate the shape of the capsulotomy in terms of diameter, area, and circularity. PCO score was evaluated using EPCO 2000 software. Best corrected visual acuity (BCVA) and endothelial cell count (ECC) were evaluated before and after surgery at 1 and 18 \ub1 2 months. Results. At 18 months, mean capsulotomy diameter was 5.34 \ub1 0.21 mm while capsulorhexis was 5.87 \ub1 0.37 mm (p<0.001) and the deviation area from baseline was 1.13 \ub1 1.76 mm2 in FLACS and 2.67 \ub1 1.69 mm2 in B-MICS (p<0.001). Capsulotomy circularity was 0.94 \ub1 0.04 while capsulorhexis was 0.83 \ub1 0.07 (p<0.001). EPCO score was 0.050 \ub1 0.081 in the FLACS group and 0.122 \ub1 0.239 in the B-MICS group (p=0.03). The mean BCVA improvement was significant in both groups, without a significant difference at 18 months. We noticed a statistically significant difference in endothelial cell loss at 18 months (FLACS 12.4% and B-MICS 18.1%; p=0.017). Conclusions. Bimanual FLACS is a safe and effective technique, as determined in a long-term follow-up. Capsulotomy shape presented higher stability and circularity in the FLACS group over the 18-month observation period. FLACS resulted in lower PCO scores and endothelial cell loss at 18 months in comparison to B-MICS standard technique