Self-pulsing and dual-mode lasing in a square microcavity semiconductor laser.

Self-pulsing and dual-mode lasing in a square microcavity semiconductor laser are studied experimentally. Self-sustained pulses originating from undamped relaxation oscillation induced by a two-mode interaction are obtained, as the injection current is slightly above the laser threshold. A repetition frequency of 4.4 GHz and a pulse width of 30-40 ps are obtained at a current of 8 mA. The laser switches to continuous-wave operation when the injection current is higher than a certain value, and dual-mode lasing with 30.7 GHz at 16 mA and 10.7 GHz at 27 mA are observed in the lasing spectra. Furthermore, the relative intensity noise spectra are presented to reveal the relationship between the lasing states and the dynamics induced by relaxation oscillation and mode beating.

Wideband frequency-tunable optoelectronic oscillator with a directly modulated AlGaInAs/InP integrated twin-square microlaser.

We propose and demonstrate an optoelectronic oscillator with a directly modulated AlGaInAs/InP integrated twin-square microlaser for generating wideband frequency-tunable microwave signals with low phase noise. Apart from the relaxation oscillation peak, the modulation response of the twin-square microlaser working at the mutual optical injection state exhibits a significant enhancement around the beating frequency of the lasing modes in the two square cavities owing to the photon-photon resonance. A self-sustaining oscillation can be generated around the modulation response peak with the lowest loop loss occurring at the relaxation oscillation frequency or the beating frequency, depending on the practical state of the twin-square microlaser. High-quality tunable microwave signals ranging from 2.22 to 19.52 GHz are generated with single sideband phase noises below -110 dBc/Hz at the 10 kHz offset frequency and side-mode suppression ratios of approximately 40 dB by tuning the injection currents of the twin-square microlaser.

[Efficacy of two bariatric surgeries in type 2 diabetic patients with a body mass index of 25-27.5].

OBJECTIVE: To evaluate the therapeutic effects of laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic duodenal-jejunal bypass with sleeve gastrectomy (SADJB-SG) in patients with type 2 diabetes mellitus and a low body mass index (BMI) of 25-27.5. METHODS: Thirty-one type 2 diabetic patients with a BMI of 25-27.5 underwent bariatric surgeries in the General Hospital of Guangzhou Military Command between August, 2013 and August, 2015. The patients receiving LRYGB (17 cases) and SADJB-SG (14 cases) were compared for physical indexes, glucose metabolism and of pancreatic islet function at 1 year after the surgeries. RESULTS: No mortality occurred in the patients after the operations. At 1 year after the operation, the patients in LRYGB group showed significant improvements in body weight, BMI, glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), oral glucose tolerance test 2 h (OGTT2h), C-peptide, fasting insulin (FINS), and postprandial 2 hour insulin (2 hPINS) (P<0.05); in SADJB-SG group, significant improvements were observed in the body weigh, BMI, HbA1c, FPG, OGTT2h, and FINS after the operation (P<0.05). The postoperative improvements in body weigh, BMI, HbA1c, FPG, OGTT2h, C-peptide, and 2hPINS were comparable between SADJB-SG group and LRYGB group (P>0.05), but the incidence of postoperative anastomotic ulcer was lower in SADJB-SG group. CONCLUSION: SADJB-SG and LRYGB produce similar therapeutic effects in type 2 diabetic patients with a low BMI, but SADJB-SG is associated with a low incidence of postoperative complications and is therefore more suitable in such patients.

Inhaled budesonide and oral dexamethasone prevent acute mountain sickness.

BACKGROUND: This double-blind, randomized controlled trial aimed to investigate inhaled budesonide and oral dexamethasone compared with placebo for their prophylactic efficacy against acute mountain sickness after acute high-altitude exposure. METHODS: There were 138 healthy young male lowland residents recruited and randomly assigned to receive inhaled budesonide (200 µg, twice a day [bid]), oral dexamethasone (4 mg, bid), or placebo (46 in each group). They traveled to 3900 m altitude from 400 m by car. Medication started 1 day before high-altitude exposure and continued until the third day of exposure. Primary outcome measure was the incidence of acute mountain sickness after exposure. RESULTS: One hundred twenty-four subjects completed the study (42, 39, and 43 in the budesonide, dexamethasone, and placebo groups, respectively). Demographic characteristics were comparable among the 3 groups. After high-altitude exposure, significantly fewer participants in the budesonide (23.81%) and dexamethasone (30.77%) groups developed acute mountain sickness compared with participants receiving placebo (60.46%) (P = .0006 and P = .0071, respectively). Both the budesonide and dexamethasone groups had lower heart rate and higher pulse oxygen saturation (SpO2) than the placebo group at altitude. Only the budesonide group demonstrated less deterioration in forced vital capacity and sleep quality than the placebo group. Four subjects in the dexamethasone group reported adverse reactions. CONCLUSIONS: Both inhaled budesonide (200 µg, bid) and oral dexamethasone (4 mg, bid) were effective for the prevention of acute mountain sickness, especially its severe form, compared with placebo. Budesonide caused fewer adverse reactions than dexamethasone.