Magneto-Acoustic Waves in antiferromagnetic CuMnAs excited by Surface Acoustic Waves

Magnetoelastic effects in antiferromagnetic CuMnAs are investigated by applying dynamic strain in the 0.01% range through surface acoustic waves in the GaAs substrate. The magnetic state of the CuMnAs/GaAs is characterized by a multitude of submicron-sized domains which we image by x-ray magnetic linear dichroism combined with photoemission electron microscopy. Within the explored strain range, CuMnAs shows magnetoelastic effects in the form of N\'eel vector waves with micrometer wavelength, which corresponds to an averaged overall spin-axis rotation up to 2.4 deg driven by the time-dependent strain from the surface acoustic wave. Measurements at different temperatures indicate a reduction of the wave amplitude when lowering the temperature. However, no domain wall motion has been detected on the nanosecond timescal

Changes in snow cover dynamics over the Indus Basin: evidences from 2008 to 2018 MODIS NDSI trends analysis

The frozen water reserves on the Earth are not only very dynamic in their nature, but also have significant effects on hydrological response of complex and dynamic river basins. The Indus basin is one of the most complex river basins in the world and receives most of its share from the Asian Water Tower (Himalayas). In such a huge river basin with high-altitude mountains, the regular quantification of snow cover is a great challenge to researchers for the management of downstream ecosystems. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) daily (MOD09GA) and 8-day (MOD09A1) products were used for the spatiotemporal quantification of snow cover over the Indus basin and the western rivers’ catchments from 2008 to 2018. The high-resolution Landsat Enhanced Thematic Mapper Plus (ETM+) was used as a standard product with a minimum Normalized Difference Snow Index (NDSI) threshold (0.4) to delineate the snow cover for 120 scenes over the Indus basin on different days. All types of errors of commission/omission were masked out using water, sand, cloud, and forest masks at different spatiotemporal resolutions. The snow cover comparison of MODIS products with Landsat ETM+, in situ snow data and Google Earth imagery indicated that the minimum NDSI threshold of 0.34 fits well compared to the globally accepted threshold of 0.4 due to the coarser resolution of MODIS products. The intercomparison of the time series snow cover area of MODIS products indicated R2 values of 0.96, 0.95, 0.97, 0.96 and 0.98, for the Chenab, Jhelum, Indus and eastern rivers’ catchments and Indus basin, respectively. A linear least squares regression analysis of the snow cover area of the Indus basin indicated a declining trend of about 3358 and 2459 km2 per year for MOD09A1 and MOD09GA products, respectively. The results also revealed a decrease in snow cover area over all the parts of the Indus basin and its sub-catchments. Our results suggest that MODIS time series NDSI analysis is a useful technique to estimate snow cover over the mountainous areas of complex river basins

Seed Pre-Treatment and Planting Geometry Positively Influence Herbicide Efficacy in Wheat (Triticum aestivum)

ABSTRACT: An experiment was conducted to evaluate the effect of priming, planting patterns and weed control treatments on weed spectrum, grain yield and profitability of wheat, during the growing season 2013-14. Two levels of seed priming (no priming, osmopriming) and planting patterns (broadcast, row plantation), and four levels of herbicide (pyroxulam at the rate of 14.08, 10.56, 7.04 and 7.521 g a.i. ha-1) were employed in the experiment, laid out in a randomized complete block design with split-split plot arrangement. The data regarding weed density, stand establishment, growth, and yield associated traits of wheat were recorded and analyzed by analysis of variance technique using statistical software DSAASTAT. The results revealed that the final emergence count was improved significantly by line sowing. The seed priming treatments resulted in early crop emergence and canopy spread, and it also decreased weed density and dry weight by 13% and 18%, respectively at 60 DAS (days after sowing). Moreover, grain yield was improved by 8% in priming treatment plots. Whereas, line sowing of wheat treatment decreased the weed density and dry weight by 17% and 25% respectively, with improved grain yield by 14% over the broadcast method. Pyroxulam at the rate of 14.08 g a.i. ha-1 applied at 60 DAS reduced total weed density and dry weight by 88% and 96% respectively and grain yield was improved by 36% over weedy check plots. In conclusion, osmoprimed seeds (1% KCl) sown in lines 22.5 cm apart gave higher wheat yields where weeds were properly controlled through application of pyroxulam applied at its recommended dose (14.08 g a.i. ha-1) and also 75% of recommended dose under Faisalabad conditions.</jats:p

GHz sample excitation at the ALBA-PEEM

We describe a setup that is used for high-frequency electrical sample excitation in a cathode lens electron microscope with the sample stage at high voltage as used in many synchrotron light sources. Electrical signals are transmitted by dedicated high-frequency components to the printed circuit board supporting the sample. Sub-miniature push-on connectors (SMP) are used to realize the connection in the ultra-high vacuum chamber, bypassing the standard feedthrough. A bandwidth up to 4 GHz with -6 dB attenuation was measured at the sample position, which allows to apply sub-nanosecond pulses. We describe different electronic sample excitation schemes and demonstrate a spatial resolution of 56 nm employing the new setup