THE PLANARITY OF THE STICK AND ARM MOTION IN THE FIELD HOCKEY HIT

The development of relevant simulation models is one way in which our knowledge of the field hockey hit may be improved. The aim of this study was to test the appropriateness of a planar pendulum model for the motion of the stick and arms during the downswing. The hits of 13 experienced female players were filmed, and swing planes were fitted to the motion of the stickface during the downswing. Low variability in the length of a segment’s projection onto the swing plane was taken as evidence for the validity of a planar model. Coefficients of variation of less than 5% for the stick and forearm lengths supported the use of such a model for these segments, but its validity for the upper arms is less certain

The effect of topography on the steady-state wind and buoyancy-driven Subtropical Gyre

This paper studies the impact of topography and increased vertical resolution on steady-state wind and buoyancy-driven circulation in the Subtropical Gyre. Buoyancy driving is represented by mass exchange across the interface separating layers of constant density. The mass exchange in turn is parameterized in terms of the departure of a layer thickness from a reference value. A 2-layer ocean model is developed that incorporates topography that depends on the meridional co-ordinate, and the problem reduces to solving a first order partial differential equation governing the upper layer inverse planetary potential vorticity. Two distinct families of characteristic curves are required to span the entire subtropical gyre; an interior family emanating from the eastern boundary and a family lying in the northwestern corner that begin and end along the oceanic edge of the western boundary current. It is demonstrated that when the ocean shoals (deepens) poleward, the area of the recirculating gyre in the northwestern corner decreases (increases) in response to the increased (decreased) phase speed of long baroclinic Rossby waves. The model is applied to the subtropical North Atlantic gyre, using climatological Ekman pumping, zonally averaged topography and a realistic representation of the eastern boundary and the solutions are qualitatively compared with these from a general ocean circulation model. To address how increased vertical resolution modifies the recirculating gyre structure, solutions are calculated for a 3-layer flat bottom ocean model. The circulation in the top and bottom layers of this model are qualitatively similar to those in the 2-layer model. In the middle layer there is a recirculating anticyclonic gyre of extent similar to that in the 2-layer model. Outside this gyre is a second anticyclonic gyre of larger horizontal extent. The double-gyre structure in the middle layer is associated with the existence of two separatrices subdividing the layers into three regions. These curves separate two distinct families of characteristic curves each associated with the upper and lower layer inverse planetary potential vorticity equations

On the generation and propagation of Rossby waves in an ocean with a zonally shoaling mixed layer

This paper presents the theory for freely propagating and forced Rossby waves in a continuously stratified ocean where the bouyancy frequency, N, varies with longitude and depth. In this study zonal variations in N occur because the climatological mixed layer depth, h, varies with longitude.With the assumption that changes in h occur on a length scale which is large compared to a horizontal wavelength the free modes on a β-plane are examined. It is found that realistic mixed layer depth changes can cause amplitude modulations, the largest amplitudes occurring where the mixed layer is shallowest. The requirement that h variations occur slowly is removed by employing a numerical model to study the free modes in a continuously stratified meridional channel. A criterion, based on the ratio of a horizontal length scale associated with the wave packet and the internal Rossby radius, is derived for determining when a free mode may be affected by the zonal variations in the stratification. Using climatological mixed layer depth data at 35N in the Atlantic (taken from Lamb, 1984) the basin modes are numerically determined. The major response is now concentrated where the mixed layer is deepest. This apparent contradiction is explained. A general theory is presented for calculating the forced basin mode response in terms of the free modes. As an example, a wind stress curl is applied as a body force over the mixed layer for a finite duration. After the forcing is removed the percentage that each basin mode contributes to the total solution is calculated. It is found that the dominant response to wind stress curl forcing can be significantly affected by the presence of a variable depth mixed layer. The implication of this study for the interaction between baroclinic Rossby waves and mixed layer dynamics is discussed

Zero drift infrared radiation thermometer using chopper stabilised pre-amplifier

A zero-drift, mid–wave infrared (MWIR) thermometer constructed using a chopper stabilised operational amplifier (op-amp) was compared against an identical thermometer that utilised a precision op-amp. The chopper stabilised op-amp resulted in a zero-drift infrared radiation thermometer (IRT) with approximately 75% lower offset voltage, 50% lower voltage noise and less susceptibility to perturbation by external sources. This was in comparison to the precision op-amp IRT when blanked by a cover at ambient temperature. Significantly, the zero-drift IRT demonstrated improved linearity for the measurement of target temperatures between 20 °C and 70 °C compared to the precision IRT. This eases the IRT calibration procedure, leading to improvement in the tolerance of the temperature measurement of such low target temperatures. The zero-drift IRT was demonstrated to measure a target temperature of 40 °C with a reduction in the root mean square (RMS) noise from 5 K to 1 K compared to the precision IRT

On geostrophic adjustment of a two-layer, uniformly rotating fluid in the presence of a step escarpment

This paper addresses the Rossby adjustment problem for an inviscid uniformly rotating two-layer fluid in the presence of a step escarpment of infinite length. The problem can be solved analytically for the case when the ratio of the step height to the average depth of the lower layer is small. In this case two well-separated adjustment time scales emerge; the rapid, inertial and the slow, topographic vortex-stretching time scales. The fluid is assumed to be at rest initially with imposed step discontinuities in the free surface and interfacial displacements oriented perpendicular to the escarpment. A two time-scale approach shows that during the rapid inertial adjustment the fluid is not influenced by the topography. On the slow vortex-stretching time scale the fluid adjusts via the propagation of topographic Rossby waves, modified by stratification, along the step. A steady state solution is established in which the flow is geostrophically balanced in both layers. Therefore, in this steady state no fluid in the lower layer crosses the escarpment. However, cross-escarpment flow occurs in the upper layer. The volume of fluid in the upper layer that crosses the escarpment, rather than being deflected parallel to the topography, is calculated

What do we know about child abuse and neglect patterns of co-occurrence? A systematic review of profiling studies and recommendations for future research

Latent class (LCA) and latent profile (LPA) analysis represent methodological approaches to identify subgroups of maltreated individuals. Although research examining child abuse and neglect (CAN) profiles is still rare, the application of person-centered techniques to clarify CAN types co-occurrence has substantially increased in recent years. Therefore, the aim of the present study was to provide a summary and critical evaluation of the findings of LCA/LPA child maltreatment research to: (a) systemize the current understanding of patterns of maltreatment across populations and (b) elucidate interactive effects of CAN types on psychosocial functioning. A search in PsychInfo, Eric, PubMed, Scopus, and Science Direct, and Google Scholar was performed. Sixteen studies examining the co-occurrence between child physical abuse, emotional abuse, sexual abuse, neglect, and/or exposure to domestic violence were identified. A critical review of the studies revealed inconsistent findings as to the number of CAN classes, but most research uncovered a poly-victimized and a low abuse group. Further, multiple victimization was associated with most adverse internalizing and externalizing outcomes, especially when sexual abuse was present. Exposure to physical and emotional abuse was frequently reported to lead to behavioural problems. Based on the present study results, we provide a set of recommendations for surpassing the current methodological and conceptual limitations in future research

Transition phase clothing strategies and their effect on body temperature and 100-m swimming performance

Objective: Effective warm-ups are attributed to several temperature-related mechanisms. Strategies during the transition phase, preceding swimming competition, have been shown to prolong temperature-related warm-up effects. The purpose of this study was to evaluate the effects of two different clothing strategies during the transition phase, on subsequent 100-m maximal swimming performance. Methods: Nine competitive swimmers (3 female, 21 ± 3 yrs; 6 male 20 ± 2 yrs, mean performance standard 702 FINA Points, mean 100-m seasons best time 61.54 s) completed their own 30-min individual pool warm-up, followed by 7-min changing time and a 30-min transition phase, straight into a 100-m maximal effort time-trial. During the transition phase, swimmers remained seated, either wearing warm or limited clothing. Swimmers returned 1 week later, where clothing conditions were alternated. Results: Post-transition phase skin and core temperature remained higher in the warm clothing condition compared to the limited clothing condition (Mean Core: 36.90 ± 0.17°C, 36.61 ± 0.15°C, P < .01; Mean Skin: 33.49 ± 0.59°C, 31.94 ± 0.59°C, P < .01). One hundred-metre finish times were 0.6% faster in the warm clothing condition compared to the limited clothing condition (62.63 ± 7.69 s, 63.00 ± 7.75 s, P < .01). Conclusion: Wearing warm clothing during a 30-min transition phase improved swimming performance by 0.6%, compared to limited clothing

Kinematics of Women’s Sprint Canoeing Technique

Little is known about the biomechanics of sprint canoeing, especially for women’s canoeing, and a quantitative kinematic description of the motion would help coaches to develop valid technique coaching models. Five highly-trained female canoeists were filmed at 150 Hz while undertaking a 50 s maximal effort on a canoe ergometer, whose trolley motions were taken to represent those of the boat. Selected boat, body and paddle kinematics were evaluated at three key stroke cycle events (Contact, Paddle Vertical, and End of Drive) and their patterns monitored across the stroke cycle. While no clear trends between the kinematics and power output emerged, a range of strategies were identified and the data represent an initial step in the construction of detailed technique models that can be used to evaluate and monitor individual athletes

Introduction and Validation of the Juror Decision Scale (JDS): An Empirical Investigation of the Story Model

Purpose: To develop and validate a self-report measure of individual juror decision making within criminal trials, based on theoretical features set out in the Story Model of juror decision making. Methods: The Juror Decision Scale (JDS) and Acceptance of Modern Myths about Sexual Aggression (AMMSA) measure were completed by 324 jury-eligible participants split across 27 jury panels, after observing a rape trial re-enactment high in ecological validity. Dimensionality and construct validity of the JDS was investigated using traditional confirmatory factor analysis (CFA) techniques alongside confirmatory bifactor analysis at two time points (individual juror verdict decisions pre- and post-deliberation). Three competing models of the JDS were specified and tested using Mplus with maximum likelihood robust estimation. Results: Bifactor model with three meaningful factors (complainant believability, defendant believability, decision confidence) was the best fit for the data at both decision points. Good composite reliability and differential predictive validity were observed for the three JDS subscales. Conclusion: Alongside demonstrating its multidimensional conceptualisation, the JDS development permits future empirical testing of the Story Model theoretical assertions surrounding juror decision making. Present findings also provide early evidence of a certainty principle assessment process governing individual verdict decision formation. Theoretical and practical applications are discussed

The performance of the EU-Rotate_N model in predicting the growth and nitrogen uptake of rotations of field vegetable crops in a Mediterranean environment

The EU-Rotate_N model was developed as a tool to estimate the growth and nitrogen (N) uptake of vegetable crop rotations across a wide range of European climatic conditions and to assess the economic and environmental consequences of alternative management strategies. The model has been evaluated under field conditions in Germany and Norway and under greenhouse conditions in China. The present work evaluated the model using Italian data to evaluate its performance in a warm and dry environment. Data were collected from four 2-year field rotations, which included lettuce (Lactuca sativa L.), fennel (Foeniculum vulgare Mill.), spinach (Spinacia oleracea L.), broccoli (Brassica oleracea L. var. italica Plenck) and white cabbage (B. oleracea convar. capitata var. alba L.); each rotation used three different rates of N fertilizer (average recommended N1, assumed farmer's practice N2=N1+0·3×N1 and a zero control N0). Although the model was not calibrated prior to running the simulations, results for above-ground dry matter biomass, crop residue biomass, crop N concentration and crop N uptake were promising. However, soil mineral N predictions to 0·6 m depth were poor. The main problem with the prediction of the test variables was the poor ability to capture N mineralization in some autumn periods and an inappropriate parameterization of fennel. In conclusion, the model performed well, giving results comparable with other bio-physical process simulation models, but for more complex crop rotations. The model has the potential for application in Mediterranean environments for field vegetable production