Site Description for the University of Nebraska's Sandhills Agricultural Laboratory

The Sandhills Agricultural Laboratory is operated by the University of Nebraska. The laboratory is located in the south-central part of the Nebraska Sandhills near Tryon, Nebraska (41 deg. 37' N; 100 deg. 50' W). The laboratory is surrounded on the west and south by native rangeland vegetation, on the south by a large field of corn irrigated by a center pivot, and on the east by wheat stubble. This site is appropriate for moisture stress studies since rainfall is almost always inadequate to meet evaporative demands of agricultural crops during most of the growing season and the sandy soils (Valentine fine sand) at the site do not store large quantities of water. Various levels of water stress are achieved through irrigation from solid set sprinklers

Experimental and numerical studies of ferritic stainless steel tubular cross sections under combined compression and bending

An experimental and numerical study of ferritic stainless steel tubular cross sections under combined loading is presented in this paper. Two square hollow section (SHS) sizes—SHS 40×40×240×40×2 and SHS 50×50×250×50×2 made of Grade EN 1.4509 (AISI 441) stainless steel—were considered in the experimental program, which included 2 concentrically loaded stub column tests, 2 four-point bending tests, and 14 eccentrically loaded stub column tests. In parallel with the experimental investigation, a finite-element (FE) study was also conducted. Following validation of the FE models against the test results, parametric analyses were carried out to generate further structural performance data. The experimental and numerical results were analyzed and compared with the design strengths predicted by the current European stainless steel design code EN 1993-1-4 and American stainless steel design specification SEI/ASCE-8. The comparisons revealed that the codified capacity predictions for ferritic stainless steel cross sections under combined loading are unduly conservative. The deformation-based continuous strength method (CSM) has been extended to cover the case of combined loading. The applicability of CSM to the design of ferritic stainless steel cross sections under combined loading was also evaluated. The CSM was shown to offer substantial improvements in design efficiency over existing codified methods. Finally, the reliability of the proposals was confirmed by means of statistical analyses according to both the SEI/ASCE-8 requirements and those of EN 1990

Evaluation of AIS Data for Agronomic and Rangeland Vegetation: Preliminary Results for August 1984 Flight over Nebraska Sandhills Agricultural Laboratory

Since 1978 scientists from the Center for Agricultural Meteorology and Climatology at the University of Nebraska have been conducting research at the Sandhills Agricultural Laboratory on the effects of water stress on crop growth, development and yield using remote sensing techniques. We have been working to develop techniques, both remote and ground-based, to monitor water stress, phenological development, leaf area, phytomass production and grain yields of corn, soybeans and sorghum. Because of the sandy soils and relatively low rainfall at the site it is an excellent location to study water stress without the necessity of installing expensive rainout shelters. The primary objectives of research with the airborne imaging spectrometer (AIS) data collected during an August 1984 flight over the Sandhills Agricultural Laboratory are to evaluate the potential of using AIS to: (1) discriminate crop type; (2) to detect subtle architectural differences that exist among different cultivars or hybrids of agronomic crops; (3) to detect and quantify, if possible, the level of water stress imposed on the crops; and (4) to evaluate leaf area and biomass differences for different crops

On the pharmacology of the iodides

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How, when and why do young women use nutrition information on food labels? A qualitative analysis

Background. Nutrition information on food packaging offers a public health tool which could be used to promote informed consumer choice and aid consumption of a healthy diet. Research indicates that use of nutrition information can lead to reduced energy intake and lower BMI, but little evidence is available regarding how, when or why people use nutrition information when making everyday food choices. Methods. This qualitative study explored motivations and contexts surrounding the use of nutrition information among 25 UK-based female nutrition information users aged 23-35 years, using semi-structured individual interviews. Verbatim transcripts were analysed using thematic analysis. Results. Six themes were identified: (1) understanding and (2) functions of nutrition information, (3) health versus appearance motives, nutrition information use in (4) affective and (5) symbolic food episodes, and (6) competing point-of-purchase influences. Notable observations included a difficulty in understanding and converting nutrition information into personally meaningful terms, and eschewal of nutrition information in settings where food plays an affective or symbolic role (e.g. food consumption after a stressful day, buying food for a dinner party). Conclusions. We suggest evidence-based directions for future research and offer policy and practice recommendations, including the adoption of clear and consistent nutrition information formats

Buckling of ferritic stainless steel members under combined axial compression and bending

Experimental and numerical studies of ferritic stainless steel beam-columns have been carried out and are described in this paper. Two cross-section sizes were considered in the physical testing: square hollow section (SHS) 60 × 60 × 3 and rectangular hollow section (RHS) 100 × 40 × 2, both of grade EN 1.4003 stainless steel. The experimental programme comprised material tensile coupon tests, geometric imperfection measurements, four stub column tests, two four-point bending tests, two axially-loaded column tests and ten beam-column tests. The initial eccentricities for the beam-column tests were varied to provide a wide range of bending moment-to-axial load ratios. All the test results were then employed for the validation of finite element (FE) models, by means of which a series of parametric studies was conducted to generate further structural performance data. The obtained test and FE results were utilized to evaluate the accuracy of the capacity predictions according to the current European code, American specification and Australian/New Zealand Standard, together with other recent proposals, for the design of stainless steel beam-columns. Overall, the Australian/New Zealand Standard was found to offer the most suitable design provisions, though further improvements remain possible

Experimental study of ferritic stainless steel tubular beam-column members subjected to unequal end moments

This paper presents a comprehensive experimental study of the buckling behavior of ferritic stainless steel tubular section beam-column structural members subjected to unequal end moments. Testing was carried out on two cold-formed and seam-welded cross sections—one rectangular hollow section (RHS) 100×40×2100×40×2 and one square hollow section (SHS) 60×60×360×60×3 made of grade AISI 410 (EN 1.4003) stainless steel. The experimental investigation included a series of material tensile coupon tests, initial local and global geometric imperfection measurements and 24 beam-column tests under unequal end moments. The experimental setup and procedures are described, and the test observations, including the key test results, the load-deformation histories, and the failure modes, are fully reported. The experimental results were carefully analyzed and then compared with the design strength predictions determined according to the current European code, American specification, and Australian/New Zealand standard for stainless steel structures, enabling the accuracy of each codified method to be evaluated. Generally, the European code resulted in the most conservative and scattered strength predictions among the three codified approaches, owing principally to the use of the same treatment for stainless steel beam-columns under both equal and unequal end moments. The American specification and Australian/New Zealand standard employ an equivalent uniform moment factor to consider the beneficial effects of moment gradient on beam-column strengths. These approaches were shown to offer more accurate and consistent capacity predictions for ferritic stainless steel beam-columns under unequal end moments, though further improvements remain possible

CFDST sections with square stainless steel outer tubes under axial compression: experimental investigation, numerical modelling and design

The use of concrete-filled double skin tubular (CFDST) cross-sections for compression members has become increasingly popular in construction. A recently proposed innovative form of CFDST cross-section, ultilising stainless steel for the outer tube, offers the combined advantages of the composite action seen in CFDST member alongside the durability and ductility associated with stainless steel. CFDST sections with stainless steel outer tubes, for which there are currently little experimental data, are the focus of the present study. A comprehensive experimental and numerical investigation into the compressive behaviour of CFDST sections with square stainless steel outer tubes is presented in this paper. A total of 19 specimens was tested under uniform axial compression, and the test observations are fully reported. The ultimate loads, load-displacement curves and failure modes from the tests were used for the validation of finite element (FE) models. Parametric finite element analyses were then performed. The combined set of experimentally and numerically derived data was employed to assess the applicability of the existing European, Australian and American design provisions for composite carbon steel members to the design of the studied CFDST cross-sections. Overall, the existing design rules are shown to provide generally safe-sided (less so for the higher concrete grades) but rather scattered capacity predictions. Modifications to the current design codes are also considered—a higher buckling coefficient k of 10.67 to consider the beneficial restraining effect of the concrete on the local buckling of the stainless steel outer tubes, as well as a reduction factor η to reflect the reduced relative effectiveness of higher concrete grades. Overall, the comparisons demonstrated that improved accuracy and consistency were achieved when the modified design rules were applied