Forced mode locking in a semiconductor laser

A brief description of the theory of mode locking of a semiconductor laser when the modulating generator frequency is close to the intermode frequency is given. It is shown that during mode locking there is phase locking, due to which the dispersion of summed intensity in the interpulse interval tends to zero.

Point process temporal structure characterizes electrodermal activity

Electrodermal activity (EDA) is a direct readout of the body’s sympathetic nervous system measured as sweat-induced changes in the skin’s electrical conductance. There is growing interest in using EDA to track physiological conditions such as stress levels, sleep quality, and emotional states. Standardized EDA data analysis methods are readily available. However, none considers an established physiological feature of EDA. The sympathetically mediated pulsatile changes in skin sweat measured as EDA resemble an integrate-and-fire process. An integrate-and-fire process modeled as a Gaussian random walk with drift diffusion yields an inverse Gaussian model as the interpulse interval distribution. Therefore, we chose an inverse Gaussian model as our principal probability model to characterize EDA interpulse interval distributions. To analyze deviations from the inverse Gaussian model, we considered a broader model set: the generalized inverse Gaussian distribution, which includes the inverse Gaussian and other diffusion and nondiffusion models; the lognormal distribution which has heavier tails (lower settling rates) than the inverse Gaussian; and the gamma and exponential probability distributions which have lighter tails (higher settling rates) than the inverse Gaussian. To assess the validity of these probability models we recorded and analyzed EDA measurements in 11 healthy volunteers during 1 h of quiet wakefulness. Each of the 11 time series was accurately described by an inverse Gaussian model measured by Kolmogorov–Smirnov measures. Our broader model set offered a useful framework to enhance further statistical descriptions of EDA. Our findings establish that a physiologically based inverse Gaussian probability model provides a parsimonious and accurate description of EDA.

Sitagliptin Decreases Visceral Fat and Blood Glucose in Women With Polycystic Ovarian Syndrome

Context Women with polycystic ovarian syndrome (PCOS) have decreased growth hormone (GH), which can result in increased visceral adiposity (VAT) and impaired vascular function. GH-releasing hormone, a dipeptidyl peptidase-4 (DPP4) substrate, stimulates GH secretion. Objective We tested the hypothesis that DPP4 inhibition increases GH and improves glucose levels and vascular function in women with PCOS. Methods Eighteen women with PCOS participated in a double-blind, crossover study. They received sitagliptin either 100 mg or placebo daily for 1 month, with crossover treatments separated by an 8-week washout. During each treatment, women underwent a 75-gram oral glucose tolerance test (OGTT) and assessments of vascular function and body composition. Overnight GH secretion was assessed via venous sampling every 10 minutes for 12 hours and analyzed using an automated deconvolution algorithm. Results During OGTT, sitagliptin increased glucagon-like peptide-1 (P < 0.001), early insulin secretion (from mean [± SD] insulinogenic index 1.9 ± 1.2 to 3.2 ± 3.1; P = 0.02), and decreased peak glucose (mean −17.2 mg/dL [95% CI, −27.7 to −6.6]; P < 0.01). At 1 month, sitagliptin decreased VAT (from 1141.9 ± 700.7 to 1055.1 ± 710.1 g; P = 0.02) but did not affect vascular function. Sitagliptin increased GH half-life (from 13.9 ± 3.6 to 17.0 ± 6.8 min, N = 16; P = 0.04) and interpulse interval (from 53.2 ± 20.0 to 77.3 ± 38.2 min, N = 16; P < 0.05) but did not increase mean overnight GH (P = 0.92 vs placebo). Conclusions Sitagliptin decreased the maximal glucose response to OGTT and VAT. Sitagliptin did not increase overnight GH but increased GH half-life and the interpulse interval. Clinical Trial Registration This study was registered at www.clinicaltrials.gov as NCT02122380 prior to enrollment of the first participant.

Sitagliptin decreases visceral fat and blood glucoses in women with polycystic ovarian syndrome

ContextWomen with polycystic ovarian syndrome (PCOS) have decreased growth hormone (GH), which can increase visceral adiposity (VAT) and impair vascular function. GH releasing hormone, a dipeptidyl peptidase-4 (DPP4) substrate, stimulates GH secretion.ObjectiveWe tested the hypothesis that DPP4 inhibition increases GH and improves glucose levels and vascular function in women with PCOS.MethodsEighteen women with PCOS participated in a double-blinded, cross-over study. They received sitagliptin 100 mg vs. placebo daily for one month separated by an eight-week washout. During each treatment, women underwent a 75-gram oral glucose tolerance test (OGTT), assessment of vascular function and body composition. Overnight GH secretion was assessed via venous sampling every 10 minutes for 12 hours and analyzed using an automated deconvolution algorithm.ResultsDuring OGTT, sitagliptin increased GLP-1 (p<0.001), early insulin secretion (from mean insulinogenic index 1.9±1.2 (SD) to 3.2±3.1; p=0.02) and decreased peak glucose (mean −17.2 mg/dL [95% CI −27.7, −6.6]; p<0.01). At one month, sitagliptin decreased VAT (from 1141.9±700.7 to 1055.1±710.1 g; p=0.02) but did not affect vascular function. Sitagliptin increased GH half-life (from 13.9±3.6 to 17.0±6.8 min, N=16; p=0.04) and interpulse interval (from 53.2±20.0 to 77.3±38.2 min, N=16; p<0.05) but did not increase mean overnight GH (p=0.92 vs. placebo).ConclusionsSitagliptin decreased the maximal glucose response to OGTT and VAT. Sitagliptin did not increase overnight GH but increased GH half-life and the interpulse interval.PrecisSitagliptin improved body composition and blood glucoses following oral glucose load in women with PCOS. Sitagliptin potentiated GH half-life but did not increase overnight GH levels.

Optimal stimulation parameters for intraoperative bulbocavernosus reflex in infants

OBJECTIVEThe aim of this study was to establish optimal electric stimulation parameters for intraoperatively monitoring the bulbocavernosus reflexes (BCRs) in infants.METHODSThe authors retrospectively reviewed the medical records of all infants (age < 24 months) who had undergone an untethering operation for tethered cord syndrome between May 2013 and February 2014 at a single institution and whose baseline BCR had been elicited during surgery. Using different combinations of stimulation parameters—number of stimulation pulses: 4 or 8 pulses, interpulse interval: 1, 2, or 5 msec, and polarity of stimulation: biphasic or monophasic—the authors compared the relative mean amplitude of 10 BCR responses (rmaBCRs) to each combination of parameters.RESULTSThe rmaBCRs were larger with the 8-pulse stimulations than with the 4-pulse stimulations (p < 0.0001). There was a tendency, though not statistically significant, for larger rmaBCRs to be obtained with the longer interpulse interval in the 8-pulse stimulation (p = 0.1289). The biphasic stimulation produced larger rmaBCRs than the monophasic stimulation (p = 0.0005).CONCLUSIONSBiphasic 8-pulse stimulations with 5-msec or 2-msec intervals yield the largest BCR responses. Considering that an 8-pulse stimulation with 5-msec intervals may overlap the onset of the BCR, a biphasic 8-pulse stimulation with 2-msec intervals is recommended as the optimal stimulation paradigm to monitor intraoperative BCRs in infants.

THE EFFECT OF HIGH AND LOW FREQUENCY CORTICAL STIMULATION WITH A FIXED OR A POISSON DISTRIBUTED INTERPULSE INTERVAL ON CORTICAL EXCITABILITY IN RATS

Neurostimulation is a promising treatment for refractory epilepsy. We studied the effect of cortical stimulation with different parameters in the rat motor cortex stimulation model. High intensity simulation (threshold for motor response - 100 μA), high frequency (130 Hz) stimulation during 1 h decreased cortical excitability, irrespective of the interpulse interval used (fixed or Poisson distributed). Low intensity (10 μA) and/or low frequency (5 Hz) stimulation had no effect. Cortical stimulation appears promising for the treatment of neocortical epilepsy if frequency and intensity are high enough.