MODELING OF AGRICULTURAL SYSTEMS

The authors present an overview of agricultural systems models. Beginning with why systems are modeled and for what purposes, the paper examines types of agricultural systems and associated model types. The broad categories range from pictorial (iconic) models to descriptive analogue models to symbolic (usually mathematical) models. The uses of optimization versus non-optimizing mechanistic models are reviewed, as are the scale and aggregation challenges associated with scaling up from the plant cell to the landscape or from a farm enterprise to a world market supply-demand equilibrium Recent modeling developments include the integration of formerly stand-alone biophysical simulation models, increasingly with a unifying spatial database and often for the purpose of supporting management decisions. Current modeling innovations are estimating and incorporating environmental values and other system interactions. At the community and regional scale, sociological and economic models of rural community structure are being developed to evaluate long-term community viability. The information revolution is bringing new challenges in delivering agricultural systems models over the internet, as well as integrating decision support systems with the new precision agriculture technologies.Farm Management,

Extension Needs Outreach Innovation Free from the Harms of Social Media

Despite the outreach-building benefits of social media for Extension, it is time for Extension professionals to find new innovative ways to reach out that do not involve social media. An increasing body of research has demonstrated the harms social media use imparts on the health and well-being of those in our communities. Our future use of social media as a primary method of outreach may perpetuate these harms, requiring our best efforts to develop new methods of outreach that do not negatively affect those we serve

Importance of Adding Objective Data to Stakeholder Data in Needs Assessments

When completing a needs assessment, Extension professionals should include both objective county data and stakeholder input data. Specifically, Extension professionals should identify potential areas of need, source available objective data, source data from relevant county stakeholders, and analyze similarities and differences in objective and stakeholder data. Needs assessments should be conducted in this manner to confirm the needs of a county; address risk of data skewed by subjective stakeholder opinion, particularly in small counties; and identify areas of greatest need. This method has been shown to be effective through implementation in a target rural county

Practical applications of biomechanical principles in resistance training: moments and moment arms

Exercise professionals routinely prescribe resistance training to clients with varied goals. Therefore, they need to be able to modify the difficulty of a variety of exercises and to understand how such modifications can alter the relative joint loading on their clients so to maximise the potential for positive adaptation and to minimise injury risk. This paper is the first in a three part series that will examine how a variety of biomechanical principles and concepts have direct relevance to the prescription of resistance training for the general and athletic populations as well as for musculoskeletal injury rehabilitation. In this paper, we start by defining the terms moment (torque), moment arms, compressive, tensile and shear forces as well as joint stress (pressure). We then demonstrate how an understanding of moments and moment arms is integral to the exercise professionals’ ability to develop a systematic progression of variations of common exercises. In particular, we examine how a variety of factors including joint range of motion, body orientation, type of external loading, the lifter’s anthropometric proportions and the position of the external load will influence the difficulty of each exercise variation. We then highlight the primary results of several selected studies which have compared the resistance moment arms and joint moments, forces or stresses that are encountered during selected variations of common lower body resistance training exercises. We hope that exercise professionals will benefit from this knowledge of applied resistance training biomechanics and be better able to systematically progress exercise difficulty and to modify joint loading as a result. The two remaining articles in this series will focus on the neuromechanical properties of the human musculoskeletal system and better understanding the biomechanical implications of a variety of alternative resistance training techniques, respectively

Polyethylene Frequency Spectrum from ``Warm''‐Neutron Scattering

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71280/2/JCPSA6-42-12-4299-1.pd

Theodicy and End-of-Life Care

Acknowledgments The section on Islamic perspective is contributed by information provided by Imranali Panjwani, Tutor in Theology & Religious Studies, King's College London.Peer reviewedPublisher PD

Dose-response modelling of resistance exercise across outcome domains in strength and conditioning: a meta-analysis.

Resistance exercise is the most common training modality included within strength and conditioning (S&C) practice. Understanding dose-response relationships between resistance training and a range of outcomes relevant to physical and sporting performance is of primary importance for quality S&C prescription. The aim of this meta-analysis was to use contemporary modelling techniques to investigate resistance-only and resistance-dominant training interventions, and explore relationships between training variables (frequency, volume, intensity), participant characteristics (training status, sex) and improvements across a range of outcome domains including maximum strength, power, vertical jump, change of direction, and sprinting performance. Data were obtained from a database of training studies conducted between 1962-2018, which comprised healthy trained or untrained adults engaged in resistance-only or resistance-dominant interventions. Studies were not required to include a control group. Standardized mean difference effect sizes were calculated and interventions categorized according to a range of training variables describing frequency (number of sessions per week), volume (number of sets and repetitions performed), overall intensity (intensity of effort and load, categorised as low, medium, or high), and intensity of load (represented as % 1RM prescribed). Contemporary modelling techniques including Bayesian mixed effects meta-analytic models were fitted to investigate linear and non-linear dose-responses with models compared based on predictive accuracy. Data from a total of 295 studies comprising 535 groups and 6710 participants were included with analyses conducted on time points ≤26 weeks. The best performing model included: duration from baseline, average number of sets, and the main and interaction effects between outcome domain and intensity of load (%1RM) expressed non-linearly. Model performance was not improved by the inclusion of participant training status or sex. The current meta-analysis represents the most comprehensive investigation of dose-response relationships across a range of outcome domains commonly targeted within strength and conditioning to date. Results demonstrate the magnitude of improvements are predominantly influenced by training intensity of load and the outcome measured. When considering the effects of intensity as a %1RM, profiles differ across outcome domains with maximum strength likely to be maximised with the heaviest loads, vertical jump performance likely to be maximised with relatively light loads (~30%1RM), and power likely to be maximised with low to moderate loads (40-70% 1RM)

EFFECT OF INCREASING VERTICAL CENTRE OF MASS DISPLACEMENT ON THE BIOMECHANICAL STIMULUS OF TRADITIONAL RESISTANCE TRAINING EXERCISES

This study investigated the effect of systematically increasing vertical COM displacement on the biomechanical stimulus of a traditional resistance training exercise. Fourteen male rugby union athletes performed maximum velocity repetitions of the deadlift to four different final vertical positions with external loads of 20, 40 and 60% 1RM. Significant increases in force, velocity and power were obtained with lifting techniques that resulted in greater vertical COM displacement, although significant interaction effects revealed that improvements were attenuated with heavier loads. These results have applications to strength and conditioning practice, whereby the traditional resistance training exercise stimulus can be augmented without imposing the overly large eccentric musculoskeletal loads characteristic of landing from maximal weighted vertical jumps

EFFECT OF LOAD POSITIONING ON THE KINEMATICS AND KINETICS OF WEIGHTED JUMPS

The present study sought to examine the effect of altering the position of external loads on the kinematics and kinetics of weighted vertical jumps in 29 resistance trained rugby union athletes. Vertical jumps were performed with loads of 20, 40 and 60% squat 1RM with the load positioned: 1) on the posterior aspect of the shoulder using a traditional barbell (TBJ); and 2) at arms’ length using a hexagonal barbell (HBJ). Weighted jumps performed with the load held at arms’ length resulted in significantly greater values for jump height, peak force, peak power, and peak rate of force development (