Experimental observation of electron-phonon coupling enhancement in Sn nanowires caused by phonon confinement effects

© 2019 American Physical Society. Reducing the size of a superconductor below its characteristic length scales can either enhance or suppress its critical temperature (Tc). Depending on the bulk value of the electron-phonon coupling strength, electronic and phonon confinement effects will play different roles in the modification of Tc. Experimentally disentangling each contribution has remained a challenge. We have measured both the phonon density of states and Tc of Sn nanowires with diameters of 18, 35, and 100 nm in order to quantify the effects of phonon confinement on superconductivity. We observe a shift of the phonon frequency towards the low-energy region and an increase in the electron-phonon coupling constant that can account for the measured increase in Tc.status: publishe

Whole-body vibration slows the acquisition of fat in mature female rats.

OBJECTIVE: To evaluate the effects of whole-body vibration on fat, bone, leptin and muscle mass. METHODS/DESIGN: Thirty 7-month-old female 344 Fischer rats were randomized by weight into three groups (baseline, vibration or control; n=8-10 per group). Rats in the vibration group were placed inside individual compartments attached to a Pneu-Vibe vibration platform (Pneumex, Sandpoint, ID, USA) and vibrated at 30-50 Hz (6 mm peak to peak) for 30 min per day, 5 days per week, for 12 weeks. The vibration intervention consisted of six 5-min cycles with a 1-min break between cycles. RESULTS: There were significant body composition differences between the whole-body vibration and the control group. The whole-body vibration group weighed approximately 10% less (mean+/-s.d.; 207+/-10 vs 222+/-15 g, P\u3c0.03) and had less body fat (20.8+/-3.8 vs 26.8+/-5.9 g, P\u3c0.05), a lower percentage of body fat (10.2+/-1.7 vs 12+/-2.0%, P\u3c0.05), and lower serum leptin levels (1.06+/-0.45 vs 2.27+/-0.57 ng ml(-1), P\u3c0.01) than the age-matched controls. No differences were observed for total lean mass, bone mineral content (BMC), bone mineral density (BMD), insulin-like growth factor-I (IGF-I) or soleus (SOL) and extensor digitorum longus (EDL) mass or function. Regional high-resolution dual-energy X-ray absoptiometry scans of the lumbar spine (L1-4) revealed that the whole-body vibration group had significantly greater BMC (0.33+/-0.05 vs 0.26+/-0.03 g, P\u3c0.01) and BMD (0.21+/-0.01 vs 0.19+/-0.01 g cm(-2), P\u3c0.01) than the control group. No differences between the groups were observed in the amount of food consumed. CONCLUSION: These findings show that whole-body vibration reduced body fat accumulation and serum leptin without affecting whole body BMC, BMD or lean mass. However, the increase in vertebral BMC and BMD suggests that vibration may have resulted in local increases in bone mass and density. Also, whole-body vibration did not affect muscle function or food consumption

Plasma membrane aminoglycerolipid flippase function is required for signaling competence in the yeast mating pheromone response pathway

The class 4 P-type ATPases (“flippases”) maintain membrane asymmetry by translocating phosphatidylethanolamine and phosphatidylserine from the outer leaflet to the cytosolic leaflet of the plasma membrane. In Saccharomyces cerevisiae, five related gene products (Dnf1, Dnf2, Dnf3, Drs2, and Neo1) are implicated in flipping of phosphatidylethanolamine, phosphatidylserine, and phosphatidylcholine. In MATa cells responding to α-factor, we found that Dnf1, Dnf2, and Dnf3, as well as the flippase-activating protein kinase Fpk1, localize at the projection (“shmoo”) tip where polarized growth is occurring and where Ste5 (the central scaffold protein of the pheromone-initiated MAPK cascade) is recruited. Although viable, a MATa dnf1∆ dnf2∆ dnf3∆ triple mutant exhibited a marked decrease in its ability to respond to α-factor, which we could attribute to pronounced reduction in Ste5 stability resulting from an elevated rate of its Cln2⋅Cdc28-initiated degradation. Similarly, a MATa dnf1∆ dnf3∆ drs2∆ triple mutant also displayed marked reduction in its ability to respond to α-factor, which we could attribute to inefficient recruitment of Ste5 to the plasma membrane due to severe mislocalization of the cellular phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate pools. Thus proper remodeling of plasma membrane aminoglycerolipids and phosphoinositides is necessary for efficient recruitment, stability, and function of the pheromone signaling apparatus

Musculoskeletal Frailty: A Geriatric Syndrome at the Core of Fracture Occurrence in Older Age

A progressive decline in physiologic reserves inevitably occurs with ageing. Frailty results from reaching a threshold of decline across multiple organ systems. By consequence, frail elderly experience an excess vulnerability to stressors and are at high risk for functional deficits and comorbid disorders, possibly leading to institutionalization, hospitalization and death. The phenotype of frailty is referred to as the frailty syndrome and is widely recognized in geriatric medical practice. Although frailty affects both musculoskeletal and nonmusculoskeletal systems, sarcopenia, which is defined as age-related loss of muscle mass and strength, constitutes one of the main determinants of fracture risk in older age and one of the main components of the clinical frailty syndrome. As a result, operational definitions of frailty and therapeutic strategies in older patients tend to focus on the consequences of sarcopenia. © Springer Science+Business Media, LLC 2012