Effects of salinity variations on pore water flow in salt marshes

Spatial and temporal salinity variations in surface water and pore water commonly exist in salt marshes under the combined influence of tidal inundation, precipitation, evapotranspiration, and inland freshwater input. Laboratory experiments and numerical simulations were conducted to investigate how density gradients associated with salinity variations affect pore water flow in the salt marsh system. The results showed that upward salinity (density) gradients could lead to flow instability and the formation of salt fingers. These fingers, varying in size with the distance from the creek, modified significantly the pore water flow field, especially in the marsh interior. While the flow instability enhanced local salt transport and mixing considerably, the net effect was small, causing only a slight increase in the overall mass exchange across the marsh surface. In contrast, downward salinity gradients exerted less influence on the pore water flow in the marsh soil and slightly weakened the surface water and groundwater exchange across the marsh surface. Numerical simulations revealed similar density effects on pore water flow at the field scale under realistic conditions. These findings have important implications for studies of marsh soil conditions concerning plant growth as well as nutrient exchange between the marsh and coastal marine system

Music recharges people: Synchronized music during aerobic exercise leads to better self-regulation performance.

Previous studies have demonstrated that music has a positive effect on individuals during exercise and sports. We speculate that one of the mechanisms for this positive effect may be that music reduces the consumption of self-regulation strength. The primary objective of this study was to use a self-regulation strength model to explain the impact of music on individuals during aerobic exercises. Specifically, we examined the effects of synchronous music on college students' depletion of self-regulation during aerobic exercises. The participants underwent a pre-test in which they had to maintain 50% maximum voluntary contraction (MVC) isometric grip and do exercise planning tasks. For subsequent power bicycle riding (aerobic exercise), the participants were divided into a music group and a control group. The music group performed aerobic exercises with synchronous music, while the control group performed aerobic exercises without music. After aerobic exercise, the participants underwent a post-test for isometric grip and exercise planning tasks. The results showed that the music group planned to reduce their efforts less for an upcoming exercise period (p < 0.01, d = 0.81), and their wrist flexor muscle group generated less electromyographic activation during an isometric grip task that maintained 50% MVC (p < 0.05, d = 0.80) than the control group. However, the two groups showed no difference in the duration of 50% MVC. This shows that: (a) for the same duration, participants in the music group required a lower degree of muscle activation than the control group, suggesting that music reduced the consumption of self-regulation strength in aerobic exercise; and (b) music decreased participants' planned exertion declined, also suggesting that music reduced the consumption of self-regulation strength in aerobic exercise

Effects of unstable flow on solute transport in the marsh soil and exchange with coastal water

Recent studies of marsh hydraulics have focused on tide-induced pore water circulation as the main drive for solute transport in the marsh soil and exchange with coastal water. Our study revealed another important mechanism provided by unstable fingering flow, which largely modified solute transport paths. In the marsh interior, downward penetration of salt fingers forced ambient pore water and solute plumes to move upward and exit the marsh soil through marsh platform at relatively high concentrations, up to 2 orders of magnitude higher than exit solute concentrations at the tidal creek bed. The mixing of solute with ambient pore water in the marsh interior was intensified greatly by fingering flow. A critical distance to the creek was determined based on a field-scale model simulation to distinguish tidal circulation-dominated and fingering flow-dominated solute transport zones. The new transport mechanism has implications for understanding the fate of solutes in particularly salt marshes of low creek densities

Comparing the impact of personal trainer guidance to exercising with others: Determining the optimal approach

This study aimed to examine the effects of supervised fitness training under the guidance of a personal trainer and those of competitive fitness training with others and reveal the effects of specific differences between them in a detailed manner. The study's participants consisted of 66 healthy male adults (age: 29.2 ± 5.4 years). The participants were divided into three groups: the individual training group (n = 21), which served as the control group; the exercising with a partner group (n = 22); and the group trained by a personal trainer (n = 23). Each participant was subsequently assessed using one repetition maximum bench press, squats, skeletal muscle mass, fat mass, and a questionnaire regarding nutritional plan and injury to compare the effects of training sessions over a period of 12 weeks. Among the three groups, only the group trained by a personal trainer showed an obvious enhancement in fat reduction compared to baseline (-1.61 kg, p = 0.033), which was suggestive of a salient trend that far surpassed those of the individual training group and the exercising with a partner group. Regarding squats, only the group trained by a personal trainer showed a significant change compared to the individual training group (p = 0.003). Regarding the participants' consistent use of a nutritional plan, only the group trained by a personal trainer exhibited a palpable tendency (p < 0.001); furthermore, the effect of preventing injury in the group trained by a personal trainer was more notable than that in the individual training group and the exercising with a partner group. Our results indicate that a fitness personal trainer service is effective in expediting the process of achieving fitness goals in a relatively safe manner, thereby substantiating the diversified values of the fitness personal trainer service