Health Related Physical Fitness Measures: Reference Values and Predictive Equations for Saudi Female College Students

Health related-physical fitness (HRPF) is critical for maintaining and enhancing health and quality of life. Purposes: To estimate the reference values and predictive equations for frequently used clinical field HRPF measures in a sample of Saudi female college students aged 18 - 24 years. Methods: In this cross-sectional study, body fat percentage (BF %) was estimated. Curl-up test (CUT) and sit and reach test (SRT) were applied in 216 students. The Queen’s College Step Test (QCST) was used to predict maximal oxygen consumption (VO2 max). Physical activity (PA) level was also measured using International Physical Activity Questionnaire (IPAQ). Results: The mean of BF %, SRT, CUT, and predicted VO2 max were 23.98% ± 6.13%, 17.10 ± 7.50 cm, 28.17 ± 7.72 number/min, and 39.58 ± 4.01 ml/kg/min respectively. There was no significant effect of age on all HRPF measures except for BF % (F (6,215) = 3.25, p (6,215) = 4.01, p strated that BMI was the predictor for BF % and SRT and explained 65% and 4% of total variance respectively. IPAQ score, age, and height were the predictors of CUT counting 17% of total variance. While, BMI and IPAQ score were the predictors for VO2 max and explained 13% of the total variance. Conclusion: Reference values can be used clinically in the evaluation of HRPF, in the rehabilitation process as well as in designing a program to improve the HRPF for female college students with consideration of age, height, BMI, and PA level for a particular population.

Mechanical properties and constitutive behaviors of as-cast 7050 aluminum alloy from room temperature to above the solidus temperature

The mechanical properties and constitutive behaviors of as-cast AA7050 in both the solid and semi-solid states were determined using the on-cooling and in situ solidification approaches, respectively. The results show that the strength in the solid state tends to increase with decreasing temperature. The strain rate plays an important role in the stress–strain behaviors at higher temperatures, whereas the influence becomes less pronounced and irregular when the temperature is less than 250°C. The experimental data were fitted to the extended Ludwik equation, which is suitable to describe the mechanical behavior of the materials in the as-cast state. In the semi-solid state, both the strength and ductility of the alloy are high near the solidus temperature and decrease drastically with decreasing solid fraction. As the solid fraction is less than 0.97, the maximum strength only slightly decreases, whereas the post-peak ductility begins to increase. The experimental data were fitted to the modified creep law, which is used to describe the mechanical behavior of semi-solid materials, to determine the equivalent parameter fGBWL, i.e., the fraction of grain boundaries covered by liquid phase.

STUDIES ON SELECTIVE TOXICITY OF SIX INSECTICIDES BETWEEN GREEN PEACH APHID AND LADYBIRDS

The selective toxicity of six kinds of insecticides, including imidacloprid, imidacloprid+synergist (SV1), fenvalerate, endosulfan, methomyl and dimethoate, between the green peach aphid (Myzus persicae Sulzer) and two species of ladybirds (Coccinella septempunctata Linnaeus and Propylaea japonica Thunbery), was investigated in the laboratory. The results showed that both imidacloprid WP and imidacloprid+synergist (SV1) EC possessed the highest toxicity to the aphids. Between C. septempunctata and M. persicae and between P. japonica and M. persicae, the selective toxicity ratios (STRs) of imidacloprid WP, imidacloprid+ synergist (SV1) EC and endosulfan EC were 37.6 and 13.0, 9.84 and 7.75, 54.0 and 7.28 respectively. All of them showed rather high selective toxicity. The STRs of fenvalerate EC, dimethoate EC and methomyl EC were all very low, ranging from 0.02 to 0.21, indicating their low degree of safety to the two species of ladybirds. The results demonstrated that imidacloprid WP and imidacloprid+SV1 EC not only had rather high toxicity to the aphids, but also reduced strikingly the reproduction rate and fecundity of the survival aphids. Insecticides can induce the relative fitness of insects decrease. Among the six insecticides tested with M. persicae, the following were insecticides and the order of induction was: imidacloprid + SV1> imidacloprid > endosulfan > methomyl > fenvalerate > dimethoate.