Neuromatch Academy: a 3-week, online summer school in computational neuroscience

Neuromatch Academy (https://academy.neuromatch.io; (van Viegen et al., 2021)) was designed as an online summer school to cover the basics of computational neuroscience in three weeks. The materials cover dominant and emerging computational neuroscience tools, how they complement one another, and specifically focus on how they can help us to better understand how the brain functions. An original component of the materials is its focus on modeling choices, i.e. how do we choose the right approach, how do we build models, and how can we evaluate models to determine if they provide real (meaningful) insight. This meta-modeling component of the instructional materials asks what questions can be answered by different techniques, and how to apply them meaningfully to get insight about brain function

Fixation kinetics of chelated and non-chelated zinc in semi-arid alkaline soils: application to zinc management

This study was designed to examine the fixation pattern and kinetics of zinc (Zn) in chelated (ethylenediaminetetraacetic acid, EDTA) and non-chelated mixed micronutrient systems of semi-arid alkaline soils from the Southern High Plains, USA. Soils were characterized for a suite of chemical and physical properties and data obtained from extraction experiments fitted to various kinetic models. About 30 % more plant-available Zn was fixed in the non-chelated system within the first 14 days with only about 18 % difference observed between the two systems by day 90, suggesting that the effectiveness of the chelated compounds tended to decrease over time. The strengths of the relationships of change in available Zn with respect to other micronutrients (copper, iron, and manganese) were higher and more significant in the non-chelated system (average <i>R</i>² of 0.83), compared to the chelated (average <i>R</i>² of 0.42). Fixation of plant-available Zn was best described by the power-function model (<i>R</i>² = 0.94, SE  =  0.076) in the non-chelated system, and was poorly described by all the models examined in the chelated system. Reaction rate constants and relationships generated from this study can serve as important tools for micronutrient management and for future micronutrient modeling studies on these soils and other semi-arid regions of the world

Examining the fixation kinetics of chelated and non-chelated copper and the applications to micronutrient management in semiarid alkaline soils

This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semiarid soils of the Southern High Plains, USA, using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system compared to the chelated within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrients over time, highlighting the significance of timing even when chelated micronutrients are used. The strengths of the relationship of change in available Cu with respect to other micronutrients (iron (Fe), manganese (Mn), and zinc (Zn)) were higher in the non-chelated system (<i>R</i>²: 0.68–0.94), compared to the chelated (<i>R</i>²: 0.42–0.81), with slopes of 0.40 (Cu–Fe), 0.31 (Cu–Mn), and 1.04 (Cu–Zn) in the non-chelated system and 0.26 (Cu–Fe), 0.22 (Cu–Mn), and 0.90 (Cu–Zn) in the chelated system. Reduction in the amount of available Cu was best described by the power function model (<i>R</i>² =  0.91, SE  =  0.081) in the non-chelated system and second-order model (<i>R</i>² =  0.95, SE  =  0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semiarid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies

Evaluating management-induced soil salinization in golf courses in semi-arid landscapes

Site-specific information on land management practices are often desired to make better assessments of their environmental impacts. A study was conducted in Lubbock, Texas, in the Southern High Plains of the United States, an area characterized by semi-arid climatic conditions, to (1) examine the potential management-induced alterations in soil salinity indicators in golf course facilities and (2) develop predictive relationships for a more rapid soil salinity examination within these urban landscape soils using findings from a portable X-ray fluorescence (PXRF) spectrometer. Soil samples were collected from managed (well irrigated) and non-managed (non-irrigated) areas of seven golf course facilities at 0&ndash;10, 10&ndash;20, and 20&ndash;30 cm depths and analyzed for a suite of chemical properties. Among the extractable cations, sodium (Na) was significantly (p &lt; 0.05) higher in the managed zones of all the golf facilities. Soil electrical conductivity (EC), exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR), parameters often used in characterizing soil salinity and sodicity, were for the most part significantly (p &lt; 0.05) higher in the managed areas. Water quality reports collected over a 22-year period (1991&ndash;2013, all years not available) indicated a gradual increase in pH, EC, SAR, total alkalinity, and extractable ions, thus supporting the former findings. Findings from the PXRF suggested possible differences in chemical species and sources that contribute to salinity between the managed and non-managed zones. PXRF-quantified Cl and S, and to a lesser extent Ca, individually and collectively explained 23&ndash;85% of the variability associated with soil salinity at these facilities

Elemental quantification, chemistry, and source apportionment in golf course facilities in a semi-arid urban landscape using a portable X-ray fluorescence spectrometer

This study extends the application of the portable X-ray fluorescence (PXRF) spectrometry to the examination of elements in semi-arid urban landscapes of the Southern High Plains (SHP) of the United States, focusing on golf courses. The complex environmental challenges of this region and the unique management practices at golf course facilities could lead to differences in concentration and in the chemistry of elements between managed (irrigated) and non-managed (non-irrigated) portions of these facilities. Soil samples were collected at depths of 0–10, 10–20, and 20–30 cm from managed and non-managed areas of seven different facilities in the city of Lubbock, Texas, and analyzed for a suite of soil properties. Total elemental quantification was conducted using a PXRF spectrometer. Findings mostly indicated no significant differences in the concentration of examined elements between the managed and non-managed areas of the facilities. However, strong positive relationships (<i>R</i> = 0.82&minus;0.91, <i>p</i> < 0.001) were observed among elements (e.g., Fe on the one hand and Cr, Mn, Ni, and As on the other; Cu and Zn; As and Cr) and between these elements and soil constituents or properties such as clay, calcium carbonate, organic matter, and pH. The strengths of these relationships were mostly higher in the non-managed areas, suggesting a possible alteration in the chemistry of these elements by anthropogenic influences in the managed areas. Principal component and correlation analyses within the managed areas suggested that As, Cr, Fe, Mn, and Ni could be of lithogenic origin, while Cu, Pb, and Zn could have anthropogenic influences. Only one possible, likely lithogenic, source of the elements was identified within the non-managed areas. As evidenced by the study, the PXRF spectrometer can be a valuable tool for elemental quantification and rapid investigation of elemental interaction and source apportionment in semi-arid climates

Silicene and transition metal based materials: prediction of a two-dimensional piezomagnet

We use first-principles density functional theory based calculations to determine the stability and properties of silicene, a graphene-like structure made from silicon, and explore the possibilities of modifying its structure and properties through incorporation of transition metal ions (M: Ti, Nb, Ta, Cr, Mo and W) in its lattice, forming MSi2. While pure silicene is stable in a distorted honeycomb lattice structure obtained by opposite out-of-plane displacements of the two Si sub-lattices, its electronic structure still exhibits linear dispersion with the Dirac conical feature similar to graphene. We show that incorporation of transition metal ions in its lattice results in a rich set of properties with a clear dependence on the structural changes, and that CrSi2 forms a two-dimensional magnet exhibiting a strong piezomagnetic coupling