Assessing Within-Field Variation in Alfalfa Leaf Area Index Using UAV Visible Vegetation Indices

This study examines the use of leaf area index (LAI) to inform variable-rate irrigation (VRI) for irrigated alfalfa (Medicago sativa). LAI is useful for predicting zone-specific evapotranspiration (ETc). One approach toward estimating LAI is to utilize the relationship between LAI and visible vegetation indices (VVIs) using unmanned aerial vehicle (UAV) imagery. This research has three objectives: (1) to measure and describe the within-field variation in LAI and canopy height for an irrigated alfalfa field, (2) to evaluate the relationships between the alfalfa LAI and various VVIs with and without field average canopy height, and (3) to use UAV images and field average canopy height to describe the within-field variation in LAI and the potential application to VRI. The study was conducted in 2021–2022 in Rexburg, Idaho. Over the course of the study, the measured LAI varied from 0.23 m2 m−2 to 11.28 m2 m−2 and canopy height varied from 6 cm to 65 cm. There was strong spatial clustering in the measured LAI but the spatial patterns were dynamic between dates. Among eleven VVIs evaluated, the four that combined green and red wavelengths but excluded blue wavelengths showed the most promise. For all VVIs, adding average canopy height to multiple linear regression improved LAI prediction. The regression model using the modified green–red vegetation index (MGRVI) and canopy height (R2 = 0.93) was applied to describe the spatial variation in the LAI among VRI zones. There were significant (p \u3c 0.05) but not practical differences

Integrated use of phosphorus fertilizer and farmyard manure improves wheat productivity by improving soil quality and P availability in calcareous soil under subhumid conditions

IntroductionLow soil fertility and high fertilizer costs are constraints to wheat production, which may be resolved with integrating fertilizer phosphorus (P) and farm-yard manure (FYM). Study objectives were to evaluate P source impacts on soil, P efficiency, and wheat growth in a calcareous soil.MethodsTreatments included P fertilizer (0, 17, 26, or 39 kg P ha-1) and/or FYM (0 or 10 T ha-1) in a: 1) incubation experiment and 2) wheat (Triticum aestivum spp.) field experiment.Results and DiscussionSoil organic matter increased (30-72%) linearly for both fertilizer and FYM, whereas pH decreased (0.1-0.3 units) with fertilizer only. Addition of fertilizer and FYM increased plant available P (AB-DTPA extractable soil P) an average of 0.5 mg P kg-1 soil week-1 with incubation. The initial increase was 1-9 mg P kg-1, with further increase after 84 d of ~3-17 mg P kg-1. There was also a significant increase of available P in the soil supporting plants in the field study, although the magnitude of the increase was only 2 mg kg-1 at most for the highest fertilizer rate + FYM. Grain (66 to 119%) and straw (25-65%) yield increased significantly, peaking at 26 kg P ha-1 + FYM. The P Absorption Efficiency (PAE), P Balance (PB), and P Uptake (PU) increased linearly with P rate, with the highest levels at the highest P rate. The P Use Efficiency (PUE) was highest at the lowest rates of P, with general decreases with increasing P, although not consistently. Principal component analysis revealed that 94.34 % of the total variance was accounted for with PC1 (84.04 %) and PC2 (10.33 %), with grain straw yield significantly correlated to SOM, PU, and PAE. Regression analysis showed highly significant correlation of PB with P-input (R2= 0.99), plant available P (R2= 0.85), and PU (R2= 0.80). The combination of FYM at the rate of 10 T ha-1 and fertilizer P at 26 kg P ha-1 was found as the optimum dose that significantly increased yield. It is concluded that FYM concoction with fertilizer-P not only improved SOM and residual soil P, but also enhanced wheat yields with reasonable P efficiency

Blazars in the early Universe

We investigate the relative occurrence of radio--loud and radio-quiet quasars in the first billion years of the Universe, powered by black holes heavier than one billion solar masses. We consider the sample of high-redshfit blazars detected in the hard X-ray band in the 3-years all sky survey performed by the Burst Alert Telescope (BAT) onboard the Swift satellite. All the black holes powering these blazars exceed a billion solar mass, with accretion luminosities close to the Eddington limit. For each blazar pointing at us, there must be hundreds of similar sources (having black holes of similar masses) pointing elsewhere. This puts constraints on the density of billion solar masses black holes at high redshift (z>4), and on the relative importance of (jetted) radio-loud vs radio-quiet sources. We compare the expected number of high redshift radio--loud sources with the high luminosity radio-loud quasars detected in the Sloan Digital Sky Survey (SDSS), finding agreement up to z~3, but a serious deficit at z>3 of SDSS radio-loud quasars with respect to the expectations. We suggest that the most likely explanations for this disagreement are: i) the ratio of blazar to misaligned radio-sources decreases by an order of magnitude above z=3, possibly as a result of a decrease of the average bulk Lorentz factor; ii) the SDSS misses a large fraction of radio-loud sources at high redshifts, iii) the SDSS misses both radio-loud and radio-quiet quasars at high redshift, possibly because of obscuration or because of collimation of the optical-UV continuum in systems accreting near Eddington. These explanations imply very different number density of heavy black holes at high redshifts, that we discuss in the framework of the current ideas about the relations of dark matter haloes at high redshifts and the black hole they host.Comment: MNRAS, in pres

The formation of compact massive self-gravitating discs in metal-free haloes with virial temperatures of ~ 13000-30000 K

We have used the hydrodynamical AMR code ENZO to investigate the dynamical evolution of the gas at the centre of dark matter haloes with virial velocities of ~ 20 - 30 kms and virial temperatures of ~ 13000-30000 K at z ~ 15 in a cosmological context. The virial temperature of the dark matter haloes is above the threshold where atomic cooling by hydrogen allows the gas to cool and collapse. We neglect cooling by molecular hydrogen and metals, as may be plausible if H_2 cooling is suppressed by a meta-galactic Lyman-Werner background or an internal source of Lyman-Werner photons, and metal enrichment has not progressed very far. The gas in the haloes becomes gravitationally unstable and develops turbulent velocities comparable to the virial velocities of the dark matter haloes. Within a few dynamical times it settles into a nearly isothermal density profile over many decades in radius losing most of its angular momentum in the process. About 0.1 - 1 % of the baryons, at the centre of the dark matter haloes, collapse into a self-gravitating, fat, ellipsoidal, centrifugally supported exponential disc with scale-length of ~ 0.075-0.27 pc and rotation velocities of 25-60 kms. We are able to follow the settling of the gas into centrifugal support and the dynamical evolution of the compact disc in each dark matter halo for a few dynamical times. The dynamical evolution of the gas at the centre of the haloes is complex. In one of the haloes the gas at the centre fragments into a triple system leading to strong tidal perturbations and eventually to the in-fall of a secondary smaller clump into the most massive primary clump. The formation of centrifugally supported self-gravitating massive discs is likely to be an important intermediary stage en route to the formation of a massive black hole seed.Comment: Re-submitted to MNRAS taking into account the referee's suggestions for moderate revision. 16 pages, 11 figure

Egalitarianism in surgical training: let equity prevail

This study aimed to quantify core surgical trainee (CST) differential attainment (DA) related to three cohorts; white UK graduate (White UKG) versus black and minority ethnic UKG (BME UKG) versus international medical graduates (IMGs). The primary outcome measures were annual review of competence progression (ARCP) outcome, intercollegiate Membership of the Royal College of Surgeons (iMRCS) examination pass and national training number (NTN) selection. Intercollegiate Surgical Curriculum Programme (ISCP) portfolios of 264 consecutive CSTs (2010–2017, 168 white UKG, 66 BME UKG, 30 IMG) from a single UK regional post graduate medical region (Wales) were examined. Data collected prospectively over an 8-year time period was analysed retrospectively. ARCP outcomes were similar irrespective of ethnicity or nationality (ARCP outcome 1, white UKG 60.7% vs BME UKG 62.1% vs IMG 53.3%, p=0.395). iMRCS pass rates for white UKG vs BME UKG vs IMG were 71.4% vs 71.2% vs 50.0% (p=0.042), respectively. NTN success rates for white UKG vs BME UKG vs IMG were 36.9% vs 36.4% vs 6.7% (p=0.023), respectively. On multivariable analysis, operative experience (OR 1.002, 95% CI 1.001 to 1.004, p=0.004), bootcamp attendance (OR 2.615, 95% CI 1.403 to 4.871, p=0.002), and UKG (OR 7.081, 95% CI 1.556 to 32.230, p=0.011), were associated with NTN appointment. Although outcomes related to BME DA were equitable, important DA variation was apparent among IMGs, with iMRCS pass 21.4% lower and NTN success sixfold less likely than UKG. Targeted counter measures are required to let equity prevail in UK CST programmes

Spatial analysis of soil moisture and turfgrass health to determine zones for spatially variable irrigation management

Irrigated turfgrass is a major crop in urban areas of the drought-stricken Western United States. A considerable proportion of irrigation water is wasted through the use of conventional sprinkler systems. While smart sprinkler systems have made progress in reducing temporal mis-applications, more research is needed to determine the most appropriate variables for accurately and cost-effectively determining spatial zones for irrigation application. This research uses data from ground and drone surveys of two large sports fields. Surveys were conducted pre-, within and towards the end of the irrigation season to determine spatial irrigation zones. Principal components analysis and k-means classification were used to develop zones using several variables individually and combined. The errors associated with uniform irrigation and different configurations of spatial zones are assessed to determine comparative improvements in irrigation efficiency afforded by spatial irrigation zones. A determination is also made as to whether the spatial zones can be temporally static or need to be re-determined periodically. Results suggest that zones based on spatial soil moisture surveys and simple observations of whether the grass felt wet or dry are better than those based on NDVI, other variables and several variables in combination. In addition, due to the temporal variations observed in spatial patterns, ideally zones should be re-evaluated periodically. However, a less labor-intensive solution is to determine temporally static zones based on patterns in soil moisture averaged from several surveys. Of particular importance are the spatial patterns observed prior to the start of the irrigation season as they reflect more temporally stable variation that relates to soil texture and topography rather than irrigation management

The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance

The all sky surveys done by the Palomar Observatory Schmidt, the European Southern Observatory Schmidt, and the United Kingdom Schmidt, the InfraRed Astronomical Satellite and the 2 Micron All Sky Survey have proven to be extremely useful tools for astronomy with value that lasts for decades. The Wide-field Infrared Survey Explorer is mapping the whole sky following its launch on 14 December 2009. WISE began surveying the sky on 14 Jan 2010 and completed its first full coverage of the sky on July 17. The survey will continue to cover the sky a second time until the cryogen is exhausted (anticipated in November 2010). WISE is achieving 5 sigma point source sensitivities better than 0.08, 0.11, 1 and 6 mJy in unconfused regions on the ecliptic in bands centered at wavelengths of 3.4, 4.6, 12 and 22 microns. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background. The angular resolution is 6.1, 6.4, 6.5 and 12.0 arc-seconds at 3.4, 4.6, 12 and 22 microns, and the astrometric precision for high SNR sources is better than 0.15 arc-seconds.Comment: 22 pages with 19 included figures. Updated to better match the accepted version in the A

Trainee perspective of the causes of stress and burnout in surgical training: a qualitative study from Wales

Objectives Stress and burn-out among surgical trainees has been reported most prevalent in core surgical trainees (CST) and female trainees in particular. This study aimed to identify factors perceived by CSTs to be associated with stress and burnout in those at risk. Design An open-ended questionnaire was distributed to 79 CSTs and two researchers categorised responses independently, according to Michie’s model of workplace stress. Setting A UK regional postgraduate medical region (Wales). Participants Sixty-three responses were received; 42 males, 21 females. The response rate was 79.7%. Results Inter-rater reliability was good (k=0.792 (79.2%), p<0.001). The most common theme of Michie’s model related to CST stress and burnout was career development, with most statements associated with curriculum, examination and academic demands required to attain a CST certificate of completion of training, and higher surgical national training number appointment. This was closely followed by those intrinsic to the job with recurrent discussion around the difficulties balancing work perceived to be service provision (ward work and on-calls), outpatient clinic and operative experience. Conversely, the most common themes relevant to stress and burnout among female trainees were associated with relationships at work (primarily the male-dominated nature of surgery), extraorganisational factors (family–work life balance) and individual characteristics (personality and physiological differences). Conclusion CSTs’ perceptions regarding the causes of National Health Service related stress and burnout are numerous, and these findings provide a basis for the development of targeted stressor counter-measures to improve training and well-being

Managing salt-affected soils for crop production

Accumulation of excessive salt in irrigated soils can reduce crop yields, reduce the effectiveness of irrigation, ruin soil structure, and affect other soil properties. This publication is designed to help you evaluate the kind and amount of salts present in soils and to select management alternatives. This publication describes the soil tests commonly used in evaluating salt-affected soils in the western U.S. and gives general guidelines for test interpretation. It will help you do the following: • Understand how sodium, calcium, and magnesium affect soil structure • Request appropriate soil analyses from commercial laboratories • Interpret soil test data • Choose appropriate practices for maintaining productivity in salt-affected soils, including: – Leaching – Amendments (kind and rate) – Crop selection – Cultural practices (e.g., tillage and bed shaping to improve seed germination) • Estimate costs and benefits of management practicesPublished November 2007. Reviewed July 2013. Please look for up-to-date information in the OSU Extension Service Catalog: http://extension.oregonstate.edu/catalo

Acidifying soil for crop production : Inland Pacific Northwest

This publication is a technical and practical guide for soil acidification in commercial fields. It explains the soil chemistry involved, how to determine whether pH adjustment is feasible, and methods for acidifying soil. This guide is divided into five sections: • Understanding soil pH • The problem—iron chlorosis • Causes of iron chlorosis • Solutions to iron chlorosis • Methods for acidifying soil in the inland Pacific NorthwestPublished September 2007. Reviewed July 2013. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo