Brushless DC Permanent Magnet Motors State of the Art

The paper presents a study of the permanent magnet brushless DC machine, from two perspectives - from authors’ own experience in designing and manufacturing such motors, as well as from actual published research. Various constructive topologies and how they influence BLDC operation, windings used with emphasis on slot, concentrated windings, are also presented. The following part describes current techniques used for enhancing BLDC limited maximum speed, such as phase advance and dwell control, somewhat similar to flux weakening in AC permanent magnet brushless motors. The paper concludes with presentation of several methods used for sensing BLDC rotor position. Overall, the authors’ intention publishing this paper was to provide an insight regarding current BLDC development, as well as to assist in making documented choices when using BLDC in specific applications.

Effects of the selective orexin-2 receptor antagonist JNJ-48816274 on sleep initiated in the circadian wake maintenance zone: a randomised trial

The effects of orexinergic peptides are diverse and are mediated by orexin-1 and orexin-2 receptors. Antagonists that target both receptors have been shown to promote sleep initiation and maintenance. Here, we investigated the role of the orexin-2 receptor in sleep regulation in a randomised, double-blind, placebo-controlled, three-period crossover clinical trial using two doses (20 and 50 mg) of a highly selective orexin-2 receptor antagonist (2-SORA) (JNJ-48816274). We used a phase advance model of sleep disruption where sleep initiation is scheduled in the circadian wake maintenance zone. We assessed objective and subjective sleep parameters, pharmacokinetic profiles and residual effects on cognitive performance in 18 healthy male participants without sleep disorders. The phase advance model alone (placebo condition) resulted in disruption of sleep at the beginning of the sleep period compared to baseline sleep (scheduled at habitual time). Compared to placebo, both doses of JNJ-48816274 significantly increased total sleep time, REM sleep duration and sleep efficiency, and reduced latency to persistent sleep, sleep onset latency, and REM latency. All night EEG spectral power density for both NREM and REM sleep were unaffected by either dose. Participants reported significantly better quality of sleep and feeling more refreshed upon awakening following JNJ-48816274 compared to placebo. No significant residual effects on objective performance measures were observed and the compound was well tolerated. In conclusion, the selective orexin-2 receptor antagonist JNJ-48816274 rapidly induced sleep when sleep was scheduled earlier in the circadian cycle and improved self-reported sleep quality without impact on waking performance.

Triple chronotherapy for the rapid treatment and maintenance of response in depressed outpatients: a feasibility and pilot randomised controlled trial

AimsTriple chronotherapy (defined as sleep deprivation for 36 hours, followed by 4 days of advancing the time of sleep, together with daily morning bright light therapy for 6 months) has demonstrated benefits for the rapid treatment of depressive symptoms in 4 small, controlled trials of in-patients. Our aims were to test the feasibility of recruitment and delivery of triple chronotherapy for out-patients with depression.MethodIn a single blind trial, 82 participants were randomised to either triple chronotherapy or a control intervention. The primary outcome was Hamilton Depression Rating Scale 6 item (HAM-D6) at 1 week. Timings of observer ratings were baseline; 1 week; 2 weeks; 4 weeks; 8 weeks and 26 weeks after randomisation. Triple chronotherapy consisted of (a) Total sleep deprivation for 36 hours. On Day 1 patients were supported in a small group to stay awake at night with an occupational therapist, (b) Phase Advance of Sleep over 4 days. Phase Advance began after the first night of sleep deprivation, when they left the hospital at about 8am and were asked to go to bed earlier at about 5pm and rise at about 1am. Their sleep and wake up times were then shifted 2 hours later on each of the following three days until they attained their usual bedtime again at about 11pm.As a control for the triple chronotherapy, participants were given psychoeducation and written information on sleep hygiene. They were also given SomniLight amber light daily for 1 week in the morning.ResultParticipants in the triple chronotherapy group were able to stay awake for the planned thirty-six hours and 89.9% adhered to the plan of phase advance of their sleep over the following 4 days. We achieved our recruitment target with 60 participants having completed the trial within 13 months. There were no reported adverse side effects. We explored outcomes and found a significant difference between the groups for the HAM-D6 at week 1, 8 and 26. Response (> 50% reduction in symptoms) was achieved by 52% in the triple chronotherapy group compared to 18% in the control group at week 1. This gradually increased to 70% achieving response in the triple chronotherapy group at week 26 compared to 22% in the control group.ConclusionTriple chronotherapy produced a significant and rapid benefit after 1 week in out-patients with depression that was sustained at 26 weeks. Further cost-effective trials with a larger clinical sample size are required.

Phase- and State-Dependent Modulation of Breathing Pattern by preBötzinger Complex Somatostatin Expressing Neurons

As neuronal subtypes are increasingly categorized, delineating their functional role is paramount. The preBötzinger Complex (preBötC) subpopulation expressing the neuropeptide somatostatin (SST) is classified as mostly excitatory, inspiratory-modulated and not rhythmogenic. We further characterized their phenotypic identity; 87% were glutamatergic and the balance were glycinergic and/or GABAergic. We then used optogenetics to investigate their modulatory role in both anesthetized and freely moving mice. In anesthetized mice, short photostimulation (100 ms) of preBötC SST+ neurons modulated breathing-related variables in a combinatory phase- and state-dependent manner; changes in inspiratory duration, inspiratory peak amplitude (Amp), and phase were different at higher (≥2.5 Hz) vs. lower (<2.5 Hz) breathing frequency. Moreover, we observed a biphasic effect of photostimulation during expiration that is probabilistic, i.e., photostimulation given at the same phase in consecutive cycles can evoke opposite responses (lengthening vs. shortening of the phase). This unexpected probabilistic state- and phase-dependent responses to photostimulation exposed properties of the preBötC that were not predicted and cannot be readily accounted for in current models of preBötC pattern generation. In freely moving mice, prolonged photostimulation decreased f in normoxia, hypoxia, or hypercapnia, and increased Amp and produced a phase advance, which was similar to the results in anesthetized mice when f≥2.5 Hz. We conclude that preBötC SST+ neurons are a key mediator of the extraordinary and essential lability of breathing pattern.Key points summaryWe transfected preBötzinger Complex (preBötC) somatostatin-expressing (SST+) neurons, which modulate respiratory pattern, but are not rhythmogenic, with channelrhodopsin to investigate phase- and state-dependent modulation of breathing pattern in anesthetized and freely behaving mice in normoxia, hypoxia, and hypercapnia.In anesthetized mice, photostimulation of preBötC SST+ neurons during inspiration increased inspiratory duration and amplitude regardless of baseline breathing frequency, f.In anesthetized mice with low f (<2.5 Hz), photostimulation of preBötC SST+ neurons during expiration evoked either phase advance or phase delay, whereas in anesthetized mice with high f (≥2.5 Hz) and in freely behaving mice in normoxia, hypoxia, or hypercapnia, photostimulation always evoked phase advance.Phase- and state-dependency is a function of overall breathing network excitability.The f-dependent probabilistic modulation of breathing pattern by preBötC SST+ neurons was unexpected, requiring reconsideration of current models of preBötC function, which neither predict nor can readily account for such responses.