MICROECONOMETRIC MODELING OF HOUSEHOLD FOOD DEMAND: THE CASE OF TRANSITION BULGARIA

Considerable optimism has been expressed about the outlook for increased exports of food products to Central and Eastern Europe. A clear understanding of the potential for increased exports to this region requires comprehension of consumers' demands for food products. This analysis resents detailed elasticity estimate for food commodities in transition Bulgaria. The analysis is conducted in two segments. The first considers demand for five aggregate food commodities---cereals, fruits and vegetables, meats, dairy products, other foods (including food consumed away from home and prepared foods), and all other goods. The estimates suggest relatively price inelastic demands. We find that cereals and dairy products tend to be income-inelastic while meats and other foods are income-elastic. We also consider a Kuhn-Tucker model of demand for individual meats. These results indicate that the demands for individual meat products are very price and income elastic.Consumer/Household Economics, Demand and Price Analysis,

Relative intensity influences the degree of correspondence of jump squats and push jerks to countermovement jumps

The aim of this study was to determine the mechanical similarity between push jerk (PJ) and jump squat (JS) to countermovement jump (CMJ) and further understand the effect increasing external load may have on this relationship. Eight physically trained males (age 22 ± 3; height 176 ± 7 kg; weight 83 ± 8 kg) performed an unloaded CMJ followed by JS under a range of loads (10%, 25%, 35% and 50% 1RM back squat) and PJ (30%, 50%, 65% and 75% 1RM push jerk). A portable force platform and high speed camera both collecting at 250 Hz were used to establish joint moments and impulse during the propulsive phase of the movements. A standard inverse dynamics model was used to determine joint moment and impulse at the hip, knee and ankle. Significant correlations (p<0.05) were shown between CMJ knee joint moment and JS knee joint moment at 25% load and PJ knee joint moment at 30% and 50% load. Significant correlations were also observed between CMJ knee joint impulse and JS knee joint impulse at 10% load and PJ knee joint moment at 30% and 65% load. Significant correlation was also observed between CMJ hip joint impulse and PJ hip joint impulse at 30% load. No significant joint x load interaction was shown as load increased for either PJ or JS. Results from the study suggest partial correspondence between PJ and JS to CMJ, where a greater mechanical similarity was observed between the PJ and CMJ. This interaction is load and joint dependent where lower relative loads showed greatest mechanical similarity. Therefore utilising lower relative loads when programming may provide a greater transfer of training effect

Hip and knee joint loading during vertical jumping and push jerking

BACKGROUND: The internal joint contact forces experienced at the lower limb have been frequently studied in activities of daily living and rehabilitation activities. In contrast, the forces experienced during more dynamic activities are not well understood, and those studies that do exist suggest very high degrees of joint loading. METHODS: In this study a biomechanical model of the right lower limb was used to calculate the internal joint forces experienced by the lower limb during vertical jumping, landing and push jerking (an explosive exercise derived from the sport of Olympic weightlifting), with a particular emphasis on the forces experienced by the knee. FINDINGS: The knee experienced mean peak loadings of 2.4-4.6×body weight at the patellofemoral joint, 6.9-9.0×body weight at the tibiofemoral joint, 0.3-1.4×body weight anterior tibial shear and 1.0-3.1×body weight posterior tibial shear. The hip experienced a mean peak loading of 5.5-8.4×body weight and the ankle 8.9-10.0×body weight. INTERPRETATION: The magnitudes of the total (resultant) joint contact forces at the patellofemoral joint, tibiofemoral joint and hip are greater than those reported in activities of daily living and less dynamic rehabilitation exercises. The information in this study is of importance for medical professionals, coaches and biomedical researchers in improving the understanding of acute and chronic injuries, understanding the performance of prosthetic implants and materials, evaluating the appropriateness of jumping and weightlifting for patient populations and informing the training programmes of healthy populations. Copyright © 2012 Elsevier Ltd. All rights reserved

Peak power output in the bench pull is maximised after 4 weeks of specific power training

Maximal power production has been shown to be a differentiating factor between playing levels in many sports and is thus a focus of many strength and conditioning programmes. We sought to evaluate the duration for which a strategy of training with the optimal load (that maximises power output) will be effective in producing improvements in power output in the bench pull. The optimal load that produced the maximum power output in the bench pull was determined for twenty-one male university athletes who were randomly assigned to a group that trained with their optimal load or a load 10% of their one repetition maximum below the optimal load. Both groups completed two sessions per week for 4 weeks, after which their power output capabilities were reassessed. They then trained for a further 3 weeks with a load that was modified to reflect changes in their optimal load. The cohort as a whole had improved their peak power output by 4.6% (p = 0.002, d = 0.290) after 4 weeks of training, but experienced no further increase after another 3 weeks of training. There were no significant differences in the response to training between the two groups. This study suggests that improvements in power output can be realised within a few weeks when training with the optimal load, but training in such a way for a longer duration may be ineffective. Strength and conditioning coaches should consider periodizing power training to maximise gains in power output capabilities

Non-destructive determination of disintegration time and dissolution in immediate release tablets by terahertz transmission measurements

Purpose: The aim of this study was to establish the suitability of terahertz (THz) transmission measurements to accurately measure and predict the critical quality attributes of disintegration time and the amount of active pharmaceutical ingredient (API) dissolved after 15, 20 and 25 min for commercial tablets processed at production scale. Methods: Samples of 18 batches of biconvex tablets from a production-scale design of experiments study into exploring the design space of a commercial tablet manufacturing process were used. The tablet production involved the process steps of high-shear wet granulation, fluid-bed drying and subsequent compaction. The 18 batches were produced using a 4 factor split plot design to study the effects of process changes on the disintegration time. Non-destructive and contactless terahertz transmission measurements of the whole tablets without prior sample preparation were performed to measure the effective refractive index and absorption coefficient of 6 tablets per batch. Results: The disintegration time (R2 = 0.86) and API dissolved after 15 min (R2 = 0.96) linearly correlates with the effective refractive index, neff, measured at terahertz frequencies. In contrast, no such correlation could be established from conventional hardness measurements. The magnitude of neff represents the optical density of the sample and thus it reflects both changes in tablet porosity as well as granule density. For the absorption coefficient, αeff, we observed a better correlation with dissolution after 20 min (R2 = 0.96) and a weaker correlation with disintegration (R2 = 0.83) compared to neff. Conclusion: The measurements of neff and αeff provide promising predictors for the disintegration and dissolution time of tablets. The high penetration power of terahertz radiation makes it possible to sample a significant volume proportion of a tablet without any prior sample preparation. Together with the short measurement time (seconds), the potential to measure content uniformity and the fact that the method requires no chemometric models this technology shows clear promise to be established as a process analyser to non-destructively predict critical quality attributes of tablets

Effects of an 8-week strength training intervention on tibiofemoral joint loading during landing: a cohort study

Objectives To use a musculoskeletal model of the lower limb to evaluate the effect of a strength training intervention on the muscle and joint contact forces experienced by untrained women during landing. Methods Sixteen untrained women between 18 and 28 years participated in this cohort study, split equally between intervention and control groups. The intervention group trained for 8 weeks targeting improvements in posterior leg strength. The mechanics of bilateral and unilateral drop landings from a 30 cm platform were recorded preintervention and postintervention, as was the isometric strength of the lower limb during a hip extension test. The internal muscle and joint contact forces were calculated using FreeBody, a musculoskeletal model. Results The strength of the intervention group increased by an average of 35% (P<0.05; pre: 133±36 n, post: 180±39 n), whereas the control group showed no change (pre: 152±36 n, post: 157±46 n). There were only small changes from pre-test to post-test in the kinematics and ground reaction forces during landing that were not statistically significant. Both groups exhibited a post-test increase in gluteal muscle force during landing and a lateral to medial shift in tibiofemoral joint loading in both landings. However, the magnitude of the increase in gluteal force and lateral to medial shift was significantly greater in the intervention group. Conclusion Strength training can promote a lateral to medial shift in tibiofemoral force (mediated by an increase in gluteal force) that is consistent with a reduction in valgus loading. This in turn could help prevent injuries that are due to abnormal knee loading such as anterior cruciate ligament ruptures,patellar dislocation and patellofemoral pain

One-dimensional magnetic order in the metal–organic framework Tb(HCOO)3Tb(HCOO)_3

Variable-temperature neutron scattering measurements, reverse Monte Carlo analysis and direct Monte Carlo simulation are used to characterise magnetic order in the metal–organic framework (MOF) $Tb(HCOO)_3$ over the temperature range 100K to 1.6K = T$_N$. The magnetic transition at T$_N$ is shown to involve one-dimensional ferromagnetic ordering to a partially-ordered state related to the triangular Ising antiferromagnet and distinct from the canonical “partially-disordered antiferromagnet” model. In this phase, the direction of magnetisation of ferromagnetic chains tends to alternate between neighbouring chains but this alternation is frustrated and is not itself ordered. We suggest the existence of low-dimensional magnetic order in $Tb(HCOO)_3$ is stabilised by the contrasting strength of inter- and intra-chain magnetic coupling, itself a consequence of the underlying MOF architecture. Our results demonstrate how MOFs may provide an attractive if as yet under-explored platform for the realisation and investigation of low-dimensional physics

The Disintegration Process in Microcrystalline Cellulose Based Tablets, Part 1: Influence of Temperature, Porosity and Superdisintegrants.

Disintegration performance was measured by analysing both water ingress and tablet swelling of pure microcrystalline cellulose (MCC) and in mixture with croscarmellose sodium using terahertz pulsed imaging (TPI). Tablets made from pure MCC with porosities of 10% and 15% showed similar swelling and transport kinetics: within the first 15 s, tablets had swollen by up to 33% of their original thickness and water had fully penetrated the tablet following Darcy flow kinetics. In contrast, MCC tablets with a porosity of 5% exhibited much slower transport kinetics, with swelling to only 17% of their original thickness and full water penetration reached after 100 s, dominated by case II transport kinetics. The effect of adding superdisintegrant to the formulation and varying the temperature of the dissolution medium between 20°C and 37°C on the swelling and transport process was quantified. We have demonstrated that TPI can be used to non-invasively analyse the complex disintegration kinetics of formulations that take place on timescales of seconds and is a promising tool to better understand the effect of dosage form microstructure on its performance. By relating immediate-release formulations to mathematical models used to describe controlled release formulations, it becomes possible to use this data for formulation design. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3440-3450, 2015.S.Y. would like to thank the U. K. Engineering and Physical Sciences Research Council (EPSRC) for a studentship. J.S. and J.A.Z. would like to acknowledge the EPSRC for funding (EP/J007803/1).This is the final version. It was first published by Wiley at http://onlinelibrary.wiley.com/doi/10.1002/jps.24544/abstract

Mathematical modelling of liquid transport in swelling pharmaceutical immediate release tablets

Oral dosage forms are an integral part of modern health care and account for the majority of drug delivery systems. Traditionally the analysis of the dissolution behaviour of a dosage form is used as the key parameter to assess the performance of a drug product. However, understanding the mechanisms of disintegration is of critical importance to improve the quality of drug delivery systems. The disintegration performance is primarily impacted by the hydration and subsequent swelling of the powder compact. Here we compare liquid ingress and swelling data obtained using terahertz pulsed imaging (TPI) to a set of mathematical models. The interlink between hydration kinetics and swelling is described by a model based on Darcy's law and a modified swelling model based on that of Schott. Our new model includes the evolution of porosity, pore size and permeability as a function of hydration time. Results obtained from two sets of samples prepared from pure micro-crystalline cellulose (MCC) indicate a clear difference in hydration and swelling for samples of different porosities and particle sizes, which are captured by the model. Coupling a novel imaging technique, such as TPI, and mathematical models allows better understanding of hydration and swelling and eventually tablet disintegration.D.M. and J.A.Z. would like to acknowledge the U.K. Engineering and Physical Sciences Research Council (EPSRC) for funding (EP/L019922/1). S.Y. would like to thank the EPSRC for a studentship