Development of an early warning system of crop moisture conditions using passive microwave

Emissivities were calculated from the Nimbus 5 electrically scanning microwave radiometer (ESMR) over 25 km grid cells for the southern Great Plains includin the western two-thirds of Kansas and Oklahoma and northwest Texas. These emissivities, normalized for seasonal temperature changes, were in excellent agreement with theory and measurements made from aircraft and truck sensors at the 1.55 cm wavelength of ESMR. These emissivities were related to crop moisture conditions of the winter wheat in the major wheat producing counties of the three states. High correlations were noted between emissitivity and an antecedent precipitation index (API) used to infer soil moisture for periods when the soils were essentially bare. The emissivities from ESMR were related through API and actual crop condition reports to progress of fall planting, adequacy of crop moisture for stand establishment, and periods of excessive moisture that necessitated replanting. Periods of prolonged frozen soil in the winter were observable at several grid points. The average emissivities of the canopy/soil surface during the maximum canopy development times in the spring showed a good agreement with moisture stress inferred from rainfall and yield data

Understanding the Role of Small-Scale Flux in Solar Spectral Irradiance Variation

Global solar spectral irradiance variations depend on changes inmagnetic flux concentrations at the smallest scales. Modeling has focused on the contributions of magnetic structures in full disk images as those contributions have strong center-to-limb dependencies, but these dependencies have never been determined radiometrically; only the photometric intensity relative to some reference ’quiet-sun’1, themagnetic structure contrast, is measurable with ground based imagery. This is problematic because unre- solved inhomogeneities influence not only the full-disk structure intensities themselves, but also the quiet-sun background against which their contrast is measured. We thus argue that, to understand the physical causes underlying solar spectral irradiance varia- tions, two fundamental questionsmust be addressed: What is the real Iλ(µ) as a function of B in full-disk images? This can only be answered by imaging the Sun radiometrically from space, and we propose a Radiometric Solar Imager design. What governs spectral irradiance changes at sub arc-second scales? This can be addressed by a combination of high resolution ground based imaging (ATST-VBI) and three dimensional radiative magnetohydrodynamic modeling, and we propose a synoptic approach. Finally, a way to account for the variance introduced by unresolved substructure in spectral irradiance modeling must be devised. This is critical, as imaging and modeling at the highest resolutions but over the full solar disk will likely remain unattainable for some time

Analysis of strain and stacking faults in single nanowires using Bragg coherent diffraction imaging

Coherent diffraction imaging (CDI) on Bragg reflections is a promising technique for the study of three-dimensional (3D) composition and strain fields in nanostructures, which can be recovered directly from the coherent diffraction data recorded on single objects. In this article we report results obtained for single homogeneous and heterogeneous nanowires with a diameter smaller than 100 nm, for which we used CDI to retrieve information about deformation and faults existing in these wires. The article also discusses the influence of stacking faults, which can create artefacts during the reconstruction of the nanowire shape and deformation.Comment: 18 pages, 6 figures Submitted to New Journal of Physic

Dynamics of apparent horizons in quantum gravitational collapse

We study the gravitational collapse of a massless scalar field within the effective scenario of loop quantum gravity. Classical singularity is avoided and replaced by a quantum bounce in this model. It is shown that, quantum gravity effects predict a threshold scale below which no horizon can form as the collapse evolves towards the bounce.Comment: Contribution to the Spanish Relativity Meeting in Portugal 2012 (ERE2012), Guimaraes, Portuga

Management of benign inverted sinonasal papilloma avoiding external approaches

Even though endoscopic removal of inverted papillomas has gained popularity, many studies advocate supplementary external approaches. The impact of including the current surgical staging system into the pre-operative clinical and radiological assessment has not been systematically evaluated. We present our experience with total endoscopic management of inverted papillomas and compare the accuracy of the pre-operative predicted extent of surgery, with the actually performed surgery. From 1997 to 2005 data from 51 patients with inverted papillomas were prospectively collected and subsequently reviewed. All have been operated on endoscopically without an external approach. The overall recurrence rate was 3.9 per cent. Pre-operative prediction of extent of surgery was accurate in 26 of 51 (51 per cent). The main reasons for the inaccurate pre-operative prediction were the variable sizes and locations of the inverted papilloma bases, particularly in the maxillary sinus and the frontal recess. Our results encourage us to recommend endoscopic management as the standard treatment of benign inverted papillomas

On the line shape of the electrically detected ferromagnetic resonance

This work reviews and examines two particular issues related with the new technique of electrical detection of ferromagnetic resonance (FMR). This powerful technique has been broadly applied for studying magnetization and spin dynamics over the past few years. The first issue is the relation and distinction between different mechanisms that give rise to a photovoltage via FMR in composite magnetic structures, and the second is the proper analysis of the FMR line shape, which remains the "Achilles heel" in interpreting experimental results, especially for either studying the spin pumping effect or quantifying the spin Hall angles via the electrically detected FMR.Comment: 14 pages, 9 figure

Beamlet scraping and its influence on the beam divergence at the BATMAN Upgrade test facility

For the ITER fusion experiment, two neutral beam injectors are required for plasma heating and current drive. Each injector supplies a power of about 17 MW, obtained from neutralization of 40 A (46 A), 1 MeV (0.87 MeV) negative deuterium (hydrogen) ions. The full beam is composed of 1280 beamlets, formed in 16 beamlet groups, and strict requirements apply to the beamlet core divergence (<7 mrad). The test facility BATMAN Upgrade uses an ITER-like grid with one beamlet group, which consists of 70 apertures. In a joint campaign performed by IPP and Consorzio RFX to better assess the beam optics, the divergence of a single beamlet was compared to a group of beamlets at BATMAN Upgrade. The single beamlet is measured with a carbon fiber composite tile calorimeter and by beam emission spectroscopy, whereas the divergence of the group of beamlets is measured by beam emission spectroscopy only. When increasing the RF power at low extraction voltages, the divergence of the beamlet and of the group of beamlets is continuously decreasing and no inflection point toward an overperveant beam is found. At the same time, scraping of the extracted ion beam at the second grid (extraction grid) takes place at higher RF power, supported by the absence of the normally seen linear behavior between the measured negative ion density in the plasma close to the extraction system and the measured extracted ion current. Beside its influence on the divergence, beamlet scraping needs to be considered for the determination of the correct perveance and contributes to the measured coextracted electron current

Multiple scaling regimes in simple aging models

We investigate aging in glassy systems based on a simple model, where a point in configuration space performs thermally activated jumps between the minima of a random energy landscape. The model allows us to show explicitly a subaging behavior and multiple scaling regimes for the correlation function. Both the exponents characterizing the scaling of the different relaxation times with the waiting time and those characterizing the asymptotic decay of the scaling functions are obtained analytically by invoking a `partial equilibrium' concept.Comment: 4 pages, 3 figure