Extensive tip-splitting of injected organic liquid into an aqueous viscoelastic fluid

The injection of a fluid into another fluid causes a spatiotemporal pattern along the injection front. Viscous fingering is a well-known example when the replaced material is a viscous fluid. Notably, most fluids are, in reality, viscoelastic, i.e., they behave as an elastic solid over short timescales. For this reason, it is important to study the situation when the replaced fluid is viscoelastic. In this study, we observed a dynamics of fluids when an incompressible organic liquid was injected into an oleophilic Hele–Shaw cell filled with an aqueous viscoelastic fluid made of a wormlike micellar solution. We found extensive tip splitting of the injection front, which led to thin fingers with a characteristic size comparable to four times the cell thickness. We examined the material properties and suggest that the thin fingering pattern observed in our system is due to the delamination of viscoelastic fluid from the bottom substrate surface. Our result shows that the effect of interfacial energy in the existing solid layer should be considered in the injection process

Change in hand dexterity and habitual gait speed reflects cognitive decline over time in healthy older adults: a longitudinal study

[Purpose] There is a relationship between physical and cognitive functions; therefore, impairment of physical function would mean cognitive decline. This study aimed to investigate the association between change in physical and cognitive functions. [Subjects and Methods] Participants were 169 healthy community-dwelling older adults who attend the survey after three years from baseline (mean age, 72.4 ± 4.8 years). Grip strength, one-leg standing balance, five-times-sit-to-stand test, timed up and go, 5-m habitual walk, and a peg-moving task were used to evaluate physical performance. Five cognitive function tests were used to assess attention, memory, visuospatial function, verbal fluency, and reasoning. Cognitive function was defined as the cumulative score of these tests. [Results] At baseline, five-times-sit-to-stand test, timed up and go, and hand dexterity were independently associated with cognitive function. In longitudinal analyses, changes in habitual walking speed and hand dexterity were significantly associated with change in cognitive function. [Conclusion] Deterioration of specific physical function, such as hand dexterity and walking ability, may be associated with progression of cognitive decline. Decreasing extent of daily functions, such as hand dexterity and walking ability, can be useful indices to grasp changes in cognitive function

Preliminary Study on Aerodynamic Control of High-Angle-of-Attack Slender Body Using Blowing from Penetrating Flow Channels

The objective of this study is to experimentally verify a new aerodynamic control concept of a high-angle-of-attack slender body. In the concept, penetrating flow channels are installed to the apex of the slender body. The blowing or suction is generated at the channel exits in response to the surface pressure distribution. First, the effects of the flow channels on the aerodynamic characteristics are experimentally investigated in a low-speed wind tunnel. The result shows the Suction-Blowing type channel is the most effective because its control effect does not reduce even in higher mainstream flow velocity. The peak value of the side force and yawing moment can be reduced by up to 64% and 49%, respectively. In addition, visualization of the surface flow pattern by the oil flow method shows that the Suction-Blowing type channel makes not only the primary separation line on the body side but also the secondary separation line on the body back become symmetric

Relationships between Participation in Volunteer-Managed Exercises, Distance to Exercise Facilities, and Interpersonal Social Networks in Older Adults: A Cross-Sectional Study in Japan

This study aimed to examine the factors related to participation in volunteer-managed preventive care exercises by focusing on the distance to exercise facilities and interpersonal social networks. A postal mail survey was conducted in 2013 in Kasama City in a rural region of Japan. Older adults (aged ≥ 65 years) who were living independently (n = 16,870) were targeted. Potential participants who were aware of silver-rehabili taisou exercise (SRTE) and/or square-stepping exercise (SSE) were included in the analysis (n = 4005). A multiple logistic regression analysis revealed that social and environmental factors were associated with participation in SRTE and SSE. After adjusting for confounding variables, exercise participation was negatively associated with an extensive distance from an exercise facility in both sexes for SRTE and SSE. Among women, participation in SRTE was negatively associated with weak interpersonal social networks (odds ratio (OR) = 0.57), and participation in SRTE and SSE was negatively associated with being a car passenger (SRTE, OR = 0.76; SSE, OR = 0.60). However, there were no significant interactions between sex and social and environmental factors. Our findings suggest the importance of considering location and transportation to promote participation in preventive care exercise