Life was limited for most of Earth＇s history, remaining at a primitive stage and mostly marine until about 0.55 Ga. In the Paleozoic, life eventually exploded and colonized the continental realm. Why had there been s...Life was limited for most of Earth＇s history, remaining at a primitive stage and mostly marine until about 0.55 Ga. In the Paleozoic, life eventually exploded and colonized the continental realm. Why had there been such a long period of delayed evolution of life？ Early life was dominated by Archaea and Bacteria, which can survive ionizing radiation better than other organisms. The magnetic field preserves the atmosphere, which is the main shield of UV radiation. We explore the hypothesis that the Cambrian explosion of life could have been enabled by the increase of the magnetic field dipole intensity due to the solidification of the inner core, caused by the cooling of the Earth, and the concomitant decrease with time of the high-energy solar flux since the birth of the solar system. Therefore, the two phenomena could be responsible for the growth and thickening of the atmosphere and the development of land surface life.展开更多
Purpose This study had 2 primary aims(1)compare the effects of multi-joint vs.single-joint lower body exercise on regional muscular development of the quadriceps;and(2)compare the effects of exercises performed at dif...Purpose This study had 2 primary aims(1)compare the effects of multi-joint vs.single-joint lower body exercise on regional muscular development of the quadriceps;and(2)compare the effects of exercises performed at different knee-joint angles on hypertrophy of the triceps surae.Methods Thirty young,resistance-trained participants unilaterally performed a combination of the following lower body exercises:leg press,leg extension,straight-leg toe press,and seated calf raise.The participants’right legs were randomly allocated to perform 1 of the following 4 conditions:(1)leg press and straight-leg toe press;(2)leg-press and seated calf raise;(3)leg extension and straight-leg toe press;(4)leg extension and seated calf raise.Based on the allocated condition,the contralateral leg performed the other 2 exercises included in the protocol.Training was carried out twice per week on non-consecutive days for 8 weeks.Results Point estimates for the rectus femoris outcomes favored the single-joint exercise intervention with posterior prob-abilities ranging from 0.910≤P≤0.990.In contrast,point estimates for the vastus lateralis outcomes favored the multi-joint exercise intervention with posterior probabilities ranging from 0.875≤P≤0.994.Regarding the triceps surae,the point estimate favored straight-leg plantar flexion for muscle thickness of the medial gastrocnemius(P=0.991),with equivocal results observed for the lateral gastrocnemius and soleus.Conclusion Our findings indicate that exercise selection can influence regional hypertrophy of the muscles of the lower limbs and evidence of differences can be measured within 8 weeks.展开更多
基金The contribution of M.C. was carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA), with support from the NASA Astrobiology Institute (NAI-WARC)
文摘Life was limited for most of Earth＇s history, remaining at a primitive stage and mostly marine until about 0.55 Ga. In the Paleozoic, life eventually exploded and colonized the continental realm. Why had there been such a long period of delayed evolution of life？ Early life was dominated by Archaea and Bacteria, which can survive ionizing radiation better than other organisms. The magnetic field preserves the atmosphere, which is the main shield of UV radiation. We explore the hypothesis that the Cambrian explosion of life could have been enabled by the increase of the magnetic field dipole intensity due to the solidification of the inner core, caused by the cooling of the Earth, and the concomitant decrease with time of the high-energy solar flux since the birth of the solar system. Therefore, the two phenomena could be responsible for the growth and thickening of the atmosphere and the development of land surface life.
文摘Purpose This study had 2 primary aims(1)compare the effects of multi-joint vs.single-joint lower body exercise on regional muscular development of the quadriceps;and(2)compare the effects of exercises performed at different knee-joint angles on hypertrophy of the triceps surae.Methods Thirty young,resistance-trained participants unilaterally performed a combination of the following lower body exercises:leg press,leg extension,straight-leg toe press,and seated calf raise.The participants’right legs were randomly allocated to perform 1 of the following 4 conditions:(1)leg press and straight-leg toe press;(2)leg-press and seated calf raise;(3)leg extension and straight-leg toe press;(4)leg extension and seated calf raise.Based on the allocated condition,the contralateral leg performed the other 2 exercises included in the protocol.Training was carried out twice per week on non-consecutive days for 8 weeks.Results Point estimates for the rectus femoris outcomes favored the single-joint exercise intervention with posterior prob-abilities ranging from 0.910≤P≤0.990.In contrast,point estimates for the vastus lateralis outcomes favored the multi-joint exercise intervention with posterior probabilities ranging from 0.875≤P≤0.994.Regarding the triceps surae,the point estimate favored straight-leg plantar flexion for muscle thickness of the medial gastrocnemius(P=0.991),with equivocal results observed for the lateral gastrocnemius and soleus.Conclusion Our findings indicate that exercise selection can influence regional hypertrophy of the muscles of the lower limbs and evidence of differences can be measured within 8 weeks.
