Quantum Field Theoretical Description of Unstable Behavior of Trapped Bose-Einstein Condensates with Complex Eigenvalues of Bogoliubov-de Gennes Equations

The Bogoliubov-de Gennes equations are used for a number of theoretical works on the trapped Bose-Einstein condensates. These equations are known to give the energies of the quasi-particles when all the eigenvalues are real. We consider the case in which these equations have complex eigenvalues. We give the complete set including those modes whose eigenvalues are complex. The quantum fields which represent neutral atoms are expanded in terms of the complete set. It is shown that the state space is an indefinite metric one and that the free Hamiltonian is not diagonalizable in the conventional bosonic representation. We introduce a criterion to select quantum states describing the metastablity of the condensate, called the physical state conditions. In order to study the instability, we formulate the linear response of the density against the time-dependent external perturbation within the regime of Kubo's linear response theory. Some states, satisfying all the physical state conditions, give the blow-up and damping behavior of the density distributions corresponding to the complex eigenmodes. It is qualitatively consistent with the result of the recent analyses using the time-dependent Gross-Pitaevskii equation.Comment: 29 page

Effects of acute aerobic exercise on arterial stiffness in transgender men

Testosterone replacement therapy (TRT) in transgender men (TM) results in side effects such as elevated triglycerides and increased arterial stiffness. Exercise may be useful to ameliorate such effects, but no studies have examined the effects of acute aerobic exercise in TM. This study aimed to investigate the effects of acute aerobic exercise on arterial stiffness in TM. Thirty-six participants were included, comprising 12 TM (duration of TRT: 57.4 ± 30.3 months), 12 males and 12 females. All participants performed acute aerobic exercise on a treadmill at 50% heart rate reserve for 30 min. Arterial stiffness as measured by brachial-ankle pulse wave velocity (baPWV) was measured before exercise (Pre), 30 min after exercise (Post30), and 60 min after exercise (Post60). Serum sex hormone levels, and serum lipid profile were determined only before exercise. Serum low-density lipoprotein cholesterol (LDL-C) levels before exercise were significantly higher in TM than in males or females (males: p < 0.01; females: p < 0.05). At all points, baPWV in TM was significantly higher than in females (p < 0.05) and significantly lower than in males (p < 0.05). However, when comparing changes in baPWV over time in each group, significant decreases in Post30 and Post60 were seen in males compared to Pre (both p < 0.05), but no significant change after aerobic exercise was seen in TM or females. These results suggest that acute aerobic exercise yield different effects in TM than in males, but is unlikely to reduce arterial stiffness in TM receiving TRT

Effect of Green Tea Extract Ingestion on Fat Oxidation during Exercise in the Menstrual Cycle: A Pilot Study

In women, fat oxidation during exercise changes with the menstrual cycle. This study aimed to investigate the effect of green tea extract (GTE) ingestion on fat oxidation during exercise depending on the menstrual cycle phase. Ten women with regular menstrual cycles participated in this randomized, double-blind, crossover study. GTE or placebo was administered during the menstrual cycle’s follicular phase (FP) and luteal phase (LP). Participants cycled for 30 min at 50% maximal workload, and a respiratory gas analysis was performed. Serum estradiol, progesterone, free fatty acid, plasma noradrenaline, blood glucose, and lactate concentrations were assessed before, during, and after the exercise. Fat oxidation, carbohydrate oxidation, and the respiratory exchange ratio (RER) were calculated using respiratory gas. Fat oxidation during the exercise was significantly higher in the FP than in the LP with the placebo (p < 0.05) but did not differ between the phases with GTE. Carbohydrate oxidation, serum-free fatty acid, plasma noradrenaline, blood glucose, and lactate concentrations were not significantly different between the phases in either trial. Our results suggest that GTE ingestion improves the decrease in fat oxidation in the LP