Min Bin Research Articles

130 Individual Differences in Skin Temperature Responses to Cold Pressor Stress During Sleep Restriction and Circadian Misalignment

Abstract Introduction Individual differences in cognition during sleep restriction and circadian misalignment have been shown to be trait-like. Here we explored the consistency of individual differences in cardiovascular responses to the cold pressor test (CPT) measured by changes in the distal-proximal skin temperature gradient (DPG) using the contralateral hand to that immersed in the ice water bath, which reflects a reflex cutaneous vasoconstriction. Methods Eighteen healthy participants (8 females) mean (±SD) age 25.28 (±4.3), underwent two identical in-laboratory combined sleep restriction and circadian misalignment protocols preceded by an 8h baseline in-laboratory sleep opportunity. The participants were given a 3h sleep opportunity on night 2 and a 3h sleep opportunity on days 3 and 4 followed by recovery sleep. The CPT occurred the morning after the baseline sleep opportunity and the morning before recovery sleep. Participants maintained a seated posture beginning 30 min prior to the CPT and skin temperature was assessed starting 15 min before until 45 min after the CPT. DPG (proximal=subclavicular; distal=hand palmar) data were averaged into 3 min bins. Changes in DPG from pre-CPT and 5 min post-CPT were assessed as the primary outcome using mixed-model ANOVAs. Intra-class correlation coefficients (ICC) were calculated to measure consistency of individual differences for DPG responses. Results Mixed-model ANOVA revealed significant effects of time and combined sleep restriction and circadian misalignment on DPG during the CPT (both p<0.05), such that the DPG was wider (i.e., more negative) post-CPT and during sleep restriction and circadian misalignment. Participants showed moderately consistent DPG responses across visits 1 and 2 at baseline (ICC=0.59) and substantially consistent DPG responses during sleep restriction and circadian misalignment (ICC=0.67). Further, participants showed moderately consistent DPG responses when comparing changes between baseline and sleep restriction and circadian misalignment across visits (ICC=0.58). Conclusion Findings support that combined sleep restriction and circadian misalignment is associated with sympathetic activation and that individual differences in the DPG response to cold pressor stress are consistent. Support (if any) Office of Naval Research MURI grant N00014-15-1-2809, NIH/NCATS Colorado CTSA Grant UL1TR002535

A new method for measuring the meteor mass index: application to the 2018 Draconid meteor shower outburst

Context.Several authors predicted an outburst of the Draconid meteor shower in 2018, but with an uncertain level of activity.Aims.Optical meteor observations were used to derive the population and mass indices, flux, and radiant positions of Draconid meteors.Methods.We performed 90 min of multi-station observations after the predicted peak of activity using highly sensitive Electron Multiplying Charge Coupled Device cameras. The data calibration is discussed in detail. A novel maximum likelihood estimation method was developed to compute the population and mass index with robust error estimation. We applied the method to observed Draconids and used the values to derive the flux. Meteor trajectories were computed and compared to predicted radiant positions from meteoroid ejection models.Results.We find a mass index of 1.74 ± 0.18 in the 30 min bin after the predicted peak, and 2.32 ± 0.27 in the subsequent 60 min. The location and the dispersion of the radiant are a good match to modeled values, but there is an offset of 0.4° in solar longitude.

Max–min Bin Packing Algorithm and its application in nano-particles filling

With regard to existing bin packing algorithms, higher packing efficiency often leads to lower packing speed while higher packing speed leads to lower packing efficiency. Packing speed and packing efficiency of existing bin packing algorithms including NFD, NF, FF, FFD, BF and BFD correlates negatively with each other, thus resulting in the failure of existing bin packing algorithms to satisfy the demand of nano-particles filling for both high speed and high efficiency. The paper provides a new bin packing algorithm, Max–min Bin Packing Algorithm (MM), which realizes both high packing speed and high packing efficiency. MM has the same packing speed as NFD (whose packing speed ranks no. 1 among existing bin packing algorithms); in case that the size repetition rate of objects to be packed is over 5, MM can realize almost the same packing efficiency as BFD (whose packing efficiency ranks No. 1 among existing bin packing algorithms), and in case that the size repetition rate of objects to be packed is over 500, MM can achieve exactly the same packing efficiency as BFD. With respect to application of nano-particles filling, the size repetition rate of nano particles to be packed is usually in thousands or ten thousands, far higher than 5 or 500. Consequently, in application of nano-particles filling, the packing efficiency of MM is exactly equal to that of BFD. Thus the irreconcilable conflict between packing speed and packing efficiency is successfully removed by MM, which leads to MM having better packing effect than any existing bin packing algorithm. In practice, there are few cases when the size repetition of objects to be packed is lower than 5. Therefore the MM is not necessarily limited to nano-particles filling, and can also be widely used in other applications besides nano-particles filling. Especially, MM has significant value in application of nano-particles filling such as nano printing and nano tooth filling.

Autonomic Reflexes May Contribute to the Symptomatology of Mal de Debarquement Syndrome

Mal de debarquement syndrome (MdDS) is the phantom perception of self‐motion triggered by a passive motion event such as sea or air travel. To test the hypothesis that autonomic reflexes are altered in MdDS, head‐down rotation (HDR) was used to test vestibular reflexes and 60° head‐up tilt (HUT) was used to test combined baroreceptor and vestibular reflexes in 9 female MdDS patients and 9 age‐ and sex‐matched controls. Heart rate (HR, ECG), arterial blood pressure (ABP, finger photoplethysmography), and cardiac output (CO), stroke volume and systemic vascular resistance (SVR) were calculated (Modelflow) in 6 min bins for steady‐state and dynamic (FFT) analysis during baseline, perturbation (HDR or HUT), and recovery. HDR decreased stroke volume and CO in both groups, but SVR increased in MdDS. No changes in the ABP power spectrum were observed during HDR. HUT increased mean ABP, HR, and SVR while decreasing pulse pressure, stroke volume, and CO in both groups. Increases in mean ABP and SVR in MdDS were augmented compared to controls. HUT increased the ABP low frequency spectral power and R‐to‐R interval low frequency/high frequency ratios in both groups. These pilot data identified exaggerated vascular resistances to a postural change in MdDS possibly due to increased sympathetic reflex gain. Thus, altered autonomic reflexes appear to be a part of MdDS symptomatology.Funding: MdDS Balance Disorder Foundation

Evolution of auroral acceleration types inferred from two‐satellite coincidences

The relationship between monoenergetic electron acceleration and broadband electron acceleration is uncertain, although some have speculated that the latter is a temporal transient, and may evolve into the former. Here we have taken advantage of DMSP satellite coincidences to investigate the issue. We consider 1668 cases where one DMSP satellite observed an electron acceleration event covering at least 2 s, hence as many discrete accelerated spectra, and a second satellite subsequently observed an electron acceleration at the same location. The spatial coincidence required was tight, with a maximum separation of 0.1° magnetic latitude and 0.15 h magnetic local time. Time separations of 0–10 min were considered in 1 min bins, with auroral acceleration flagged as either monoenergetic, broadband, or a mixture of both. Within the first temporal bin (0–1 min), the second satellite had a high probability of observing the same type of aurora as the first, establishing consistency. When the first satellite observed monoenergetic aurora, the second satellite also observed monoenergetic aurora (about 80% of the time), and this continued to up to about 10 min of UT separation. In most of the other 20% of the cases, the second satellite also recorded monoenergetic acceleration but with an additional mixture of broadband acceleration. Thus monoenergetic aurora does not seem to typically evolve on a time scale of minutes. However, when the first satellite encounter was with broadband acceleration, the second encounter was highly time‐dependent, with broadband dominating the second satellite encounter only in the 0–1 min bin. Between 1 and 5 min, the probability of observing a mixture of auroral types jumped, and after 6 min, the auroral acceleration was nearly as likely to be monoenergetic as broadband. Finally, if the first satellite encountered a mixture of acceleration, the second encounter was progressively more likely to be entirely monoenergetic aurora as time increased. These results are consistent with the idea that broadband aurora may be inherently a transient, and often progresses to monoenergetic aurora, while the latter is quasi‐static.

Time Lag in Sgr A* Intra-Day Variability between the light curves at 90 and 102 GHz

AbstractWe performed the observation of the flux densities of Sgr A* at 90 and 102 GHz on 6 April 2005 using the Nobeyama Millimeter Array in order to detect the time lag between these frequencies. We constructed light curves covering a few hour with 1 min bin, and the Intra-Day Variability, which had a rising phase and intensity peak, of Sgr A* is clearly seen at both frequencies. We calculated the z-transformed discrete correlation function between the light curves of Sgr A* at 90 and 102 GHz. The derived time lag of the flares at these frequencies was approximately zero, contrary to our expectations based on the previously reported time lag at lower frequencies. If the radio flares of Sgr A* are explained by the expanding plasma model, the light curve at 90 GHz would be delayed with respect to the one at 102 GHz. However, we could not find such a delay with statistical significance in our data.

Is connexin36 critical for GABAergic hypersynchronization in the hippocampus?

Synchronous bursting of cortical GABAergic interneurons is important in epilepsies associated with excitatory GABAergic signalling. If electrical coupling was critical for the generation of this pathological activity, then the development of selective blockers of connexin36-based interneuronal gap junctions could be of therapeutic value. We have addressed this issue in the 4-aminopyridine model of epilepsy in vitro by comparing GABAergic epileptiform currents and their sensitivity to gap junction blockers in wild-type vs. connexin36 knockout mice. Although electrical coupling was abolished in stratum lacunosum-moleculare interneurons from knockout animals, epileptiform currents were not eliminated. Furthermore, epileptiform currents propagated similarly across hippocampal layers in the two genotypic groups. Blockade of electrical coupling with carbenoxolone suppressed amplitude, frequency and half-width of the epileptiform currents both in wild-type and in knockout animals, whereas mefloquine had no effects. Carbenoxolone also depressed responses to exogenous and synaptic GABA application onto interneurons. We conclude that, in the 4-aminopyridine model of epilepsy in vitro, connexin36 is not critical for the generation of epileptiform discharges in GABAergic networks and that the observed antiepileptic effects of carbenoxolone are likely to be due to blockade of GABAA receptors and not of connexin36-based gap junctions. Lastly, because of its chemical structure and its effects on amplitude and kinetics of GABAergic currents, we tested the hypothesis that carbenoxolone acted via specific sites on GABAA receptors, such as the one mediating the effects of the neurosteroid pregnenolone sulfate, or the allosteric regulatory site of benzodiazepines/β-carbolines. Our results suggest that neither of these is involved.

CLINICAL CORRELATES OF METABOLIC SYNDROME IN PATIENTS WITH CHRONIC SCHIZOPHRENIA

Clinical Correlates of Metabolic Syndrome in Patients with Chronic Schizophrenia Yoon-Young Nam, MD, Chul-Sik Kim, MD, Chul-Woo Ahn, MD, PhD, Kyung Min Park, MD, Bin Ryu, MD, and Chan-Hyung Kim, MD, PhD National Seoul Hospital, Seoul, Department of Internal Medicine, Psychiatry, Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, Korea Objectsive:This study investigated the frequency of metabolic syndrome, associated factors and its risk for cardiovascular morbidity in schizophrenic patients. Methods:In this cross-sectional study, nineteen-six patients with schizophrenia defined by DSM-IV criteria were included. All subjects were assessed for the presence of metabolic syndrome by means of the criteria of the National Cholesterol Education Program-Adult Treatment Panel III. In addition, we compared clinical characteristics, laboratory variables and risk for cardiovascular morbidity between patients with and without metabolic syndrome. Results:Of patients, 43% had metabolic syndrome. Metabolic syndrome was associated with illness chronicity and current status of antipsychotic agents use, total duration of atypical agents used, but not with daily chlorpromazine equivalent dose. Compared with the patients without metabolic syndrome, patients with metabolic syndrome had higher risk for cardiovascular morbidity. Conclusion:This study suggests that metabolic syndrome is common among patients with chronic schizophrenia. Clinicians should be cautious to aware the increased risk for the metabolic syndrome and intervene actively to prevent and treat metabolic morbidity among chronic patients with schizophrenia. (Korean J Psychopharmacol 2006;17(4):335-341)

Food intake and meal patterns of Lewis rats with continuous access to nicotine self-administration.

Nicotine is a well-known appetite suppressant, and cessation of smoking is frequently followed by weight gain in humans. The effect of elective administration of nicotine on meal parameters of rats has not been reported. In the present experiment, adult male Lewis rats were implanted with jugular vein catheters. After recovery and training to press a lever for nutritionally complete 45-mg food pellets, they were run for 23 h/day in a closed economy using a 2-lever operant chamber in which they earned all of their food and nicotine. Food pellets were available at any time on a fixed ratio (FR)5 schedule by pressing one lever. Intravenous nicotine injections (0.017 mg/kg base per injection over 1-s) were available on FR1 from the other lever. After this initial phase, the unit cost of nicotine was incremented in some rats to FR3 and FR5. Pellet deliveries and nicotine injections were recorded in 5 min bins throughout the 23 h. A 12:12 light cycle was in effect in the chamber, with the ∼1 h daily cleaning period at the end of the rats’ light period. Without explicit training, rats readily took ∼40 daily nicotine injections, but this had no effect on the amount or timing of meals relative to baseline (no drug) conditions. Most self-injections occurred nocturnally, during or near spontaneous meals. A 3-fold increase in the unit dose of nicotine yielded fewer self-injections per day but also had little effect on food intake or meal parameters. Supported in part by NIH Grant DA019288.

Charged particle periodicities in Saturn's outer magnetosphere

A Lomb periodogram analysis is applied to charged particle data from the LEMMS/CHEMS instruments on the Cassini spacecraft. The data represent count rates, averaged within 30 min bins, from electrons (28–330 keV) and protons and oxygen ions (2.8–236 keV) during 350 days in 2005 and all 365 days in 2006. Sun effects, spacecraft maneuvers, and measurements within 20 RS of Saturn were removed from the data prior to analysis. The main peaks in the frequency periodograms (or power spectra) were found within a frequency window from 9.5 hours to 12.5 hours. For signal‐to‐noise ratios exceeding 8, the periodograms within this window reveal a consistent peak near 10.80 hours (10 hours 48 min 36 sec) for all the charged particles regardless of energy or species. Even for lower signal‐to‐noise ratios, a peak near this period is generally present. The Lomb analyses are consistent with an azimuthal anomaly that rotates with a period of 10.80 hours.

Cloud‐to‐ground lightning and surface rainfall in warm‐season Florida thunderstorms

Relationships between cloud‐to‐ground (CG) lightning and surface rainfall have been examined in nine isolated, warm‐season thunderstorms on the east coast of central Florida. CG flashes and the associated rain volumes were measured as a function of time in storm‐centered reference frames that followed each storm over a network of rain gauges. Values of the storm‐average rain volume per CG flash ranged from 0.70 × 104 to 6.4 × 104 m3/CG flash, with a mean (and standard deviation) of 2.6 × 104 ± 2.1 × 104 m3/CG flash. Values of the rain volume concurrent with CG flashes ranged from 0.11 × 104 to 4.9 × 104 m3/CG flash with a mean of 2.1 × 104 ± 2.0 × 104 m3/CG flash. The lag‐time between the peak CG flash rate and the peak rainfall rate (using 5 min bins), and the results of a lag correlation analysis, show that surface rainfall tends to follow the lightning (positive lag) by up to 20 min in six storms. In one storm the rainfall preceded the lightning by 5 min, and two storms had nonsignificant lags. Values of the lagged rain volume concurrent with CG flashes ranged from 0.43 × 104 to 4.9 × 104 m3/CG flash, and the mean was 1.9 × 104 ± 1.7 × 104 m3/CG flash. For the five storms that produced 12 or more flashes and had significant lags, a plot of the optimum lag time versus the total number of CG flashes shows a linear trend (R2 = 0.56). The number of storms is limited, but the lag results do indicate that large storms tend to have longer lags. A linear fit to the lagged rain volume vs. the number of concurrent CG flashes has a slope of 1.9 × 104 m3/CG flash (R2 = 0.83). We conclude that warm‐season Florida thunderstorms produce a roughly constant rain volume per CG flash and that CG lightning can be used to estimate the location and intensity of convective rainfall in that weather regime.

Cross Correlations of Geomagnetic Field Variations Between Zhongshan and Arctic Stations

AbstractThe occurrence rates of the cross correlations of the inter‐hemispheric geomagnetic field variations are studied statistically with the magnetic data observed at Zhongshan Station, Antarctica and at Ny‐Alesund, Longyearben, Hopen Island, Bear Island and Tromso in the Arctic during Sept. 2000 to Mar. 2003, in which the criterion is that the correlation coefficient within sliding 20 min bin is larger than 0.9. It is shown that the occurrence rates of correlations of geomagnetic field variations between Zhongshan and Arctic stations are related to locations of the Arctic stations, season, local time and geomagnetic active level. Among the 5 stations in the Arctic, Longyearben is correlated most frequently with Zhongshan (17%), Ny‐Alesund or Hopen take the second place. In the equinox, the occurrence rate of correlations is higher than other seasons. In the daily variation of the occurrence rate of correlations, there is a peak in the evening and a valley at noon. The occurrence rate of correlation increases as geomagnetic activities increase.

Spatiotemporal Specificity of Neuronal Activity Directs the Modification of Receptive Fields in the Developing Retinotectal System

The precise temporal relation between pre- and postsynaptic activity modulates the strength of synaptic connections. Despite its extensive characterization in vivo and in vitro, the degree to which spike timing-dependent plasticity can shape receptive field properties is unclear. We use in vivo patch-clamp recordings of tectal neurons in developing Xenopus tadpoles to control the precise timing of action potentials with respect to the arrival of a subset of visual inputs evoked by local light stimulation on the retina. The pattern of visual inputs onto a tectal neuron was tracked over time by rapid reverse correlation mapping of receptive fields. Spike timing-dependent potentiation or depression of a subset of synapses reliably shifts the spatial receptive fields toward or away from the trained subregion of visual space, respectively. These results demonstrate that natural patterns of activity evoked by sensory stimuli play an instructive role in the developing nervous system.

Detailed analysis of the behavior of Lister and Wistar rats in anxiety, object recognition and object location tasks

The present study, examines some issues in the measure and analysis of behavior in animals. Two strains of rats of both genders were used to illustrate and discuss these issues. We examined to what extent various behavioral measures reflect different or identical emotional or cognitive factors and, how sensitive are the various parameters of a task to differences between strains and genders. Wistar and Lister males and females rats were tested in an anxiety test then in the object recognition task followed by the object location task. Taking advantage of a simple computer program it is possible to: (1) record several parameters of theses tasks and examine the pattern of animal responses toward novelty and/or familiarity; (2) examine whether different measurements of the same response would reflect anxiety response to novelty and, can they discriminate between novelty and familiarity responses to objects; and (3) examine if changes in the pattern of animal responses are reflected by these measurements and, whether anxiety or discrimination is evident mainly during the first minute of the test. The results on the anxiety test show that different measures of the same response proved concordant and revealed significant differences between Lister males and Wistar males. Lister males approached more frequently an object and spent more time on an object in each approach compared to Wistar males in the first 5 min of test and in the total 10 min. They have also shorter latencies between approaches compared to Wistar males. The examination of performance over different time bins was significant with the measure of frequency. Lister male rats approached less frequently the object in the last 5 min of the test compared to the first 5 min. Their performance, however, did not differ from that of the other groups in this last 5 min. In the memory tasks, the measure of the frequency of approaches suggests that Lister male rats were able to discriminate between novel and familiar objects and, between novel and familiar location of objects. The measure of latency of first approach shows that Wistar female rats were able to discriminate between objects only in the spatial memory test. Discrimination in the object recognition task was observed in the first and second minute, and in the total 3 min sessions. Discrimination in the object location task was observed with the measure of frequency of approaches, in the first minute, and in the total 3 min sessions. Results from the total 3 min sessions were more concordant between the different measures of discrimination than results from separate 1 min bins. The results from the two memory tasks show that novelty prevented habituation to re-exposure to the testing environment. In many cases, novelty increased exploration of the objects in the choice phase compared to the sample phase. However, this lack of habituation or increased exploration in the choice phase is not concordant with most results of discrimination between novelty and familiarity from the same type of measurements.

Ultradian rhythms of alternating cerebral hemispheric EEG dominance are coupled to rapid eye movement and non-rapid eye movement stage 4 sleep in humans

Objective: To replicate the left minus right (L−R) hemisphere EEG power shifts coupled to rapid eye movement (REM) and non-rapid eye movement (NREM) sleep observed in 1972 by Goldstein (Physiol Behav (1972) 811), and to characterize the L−R EEG power spectra for total EEG, delta, theta, alpha and beta bands. Background: Ultradian alternating cerebral hemispheric dominance rhythms are observed using EEG during both waking and sleep, and with waking cognition. The question of whether this cerebral rhythm is coupled to the REM–NREM sleep cycle and the basic rest–activity cycle (BRAC) deserves attention. Methods: L−R EEG signals for ten young, normal adult males were converted to powers and the means were normalized, smoothed and subtracted. Sleep hypnograms were compared with L−R EEGs, and spectra were computed for C3, C4 and L−R EEG powers. Results: Significant peaks were found for all C3, C4 and L−R frequency bands at the 280–300, 75–125, 55–70 and 25–50 min bins, with power dominating in the 75–125 min bin. L−R EEG rhythms were observed for all bands. Greater right hemisphere EEG dominance was found during NREM stage 4 sleep, and greater left during REM for total EEG, delta and alpha bands (Chi-squares, P<0.001). Theta was similar, but not significant ( P=0.163), and beta was equivocal. Conclusions: Earlier ultradian studies show that lateral EEG and L−R EEG power have a common pacemaker, or a mutually entrained pacemaker with the autonomic, cardiovascular, neuroendocrine and fuel-regulatory hormone systems. These results for L−R EEG coupling to sleep stages and multi-variate relations may present a new perspective for Kleitman's BRAC and for diagnosing variants of pathopsychophysiological states.

Ultradian Sleep Rhythms of Lateral Eeg, Autonomic, and Cardiovascular Activity Are Coupled in Humans

This study compared the dynamics of multiple systems during sleep with earlier results during waking rest. Three consecutive nights of data were collected from three healthy adults for 10 variables: left and right central EEGs; the nasal cycle (NC); beat-to-beat measures of CO, SV, HR, SBP, DBP, MAP, and hemoglobin-oxygen saturation. Time series analysis detected periods at 280–300, 215–275, 165–210, 145–160, 105–140, 70–100, and 40–65 min bins with the greatest spectral power in longer periods. We found significance across subjects with all parameters at 280–300, 105–140 (except left EEG power, left minus right EEG power, and HR), 70- 100, and 40–65 min. Significant periods were reported earlier during waking for the NC, pituitary hormones, cate-cholamines, insulin, and cardiovascular function in five bins at 220–340, 170–215, 115–145, 70–100, and 40–65 min, with 115–145, 70–100, and 40–65 min common across all variables. These results suggest that lateral EEG power during sleep has a common pacemaker (the hypothalamus), or a mutually entrained pacemaker, with the cardiovascular and autonomic nervous systems (ANS), and that the waking ultradians of the neuroendocririe and fuel regulatory hormones may also be coupled to lateral EEG

An assessment of the utility of an acoustic Doppler current profiler for biomass estimation

Acoustic Dopplerd current profilers (ADCPs) are being used increasingly to derive estimates of zooplankton and micronekton abundance. The absence of a practical means for users to perform ADCP calibration, however, makes the quantitative value of this approach questionable. In an attemptto evaluate ADCP-derived volume backscattering strength ( S v ) data, and hence to assess the utility of such measurements for biomass estimation, a regularly calibrated Simrad EK500 scientific echo-sounder (operating at 38, 120 and 200 kHz) and an RDI narrow-band ADCP (153.6 kHz) were similarly configured and run in synchrony on a transect in the Southern Ocean. Data were collected by both instruments from congruent depth (4 m) and time (2 min) bins in order to allow direct comparison of numerous discrete values without the need for further signal averaging. Echoes were recorded from the Antarctic krill, Euphausia superba,in deep-ocean and on-shelf locations during day and night. ADCP-derived volume back scattering strength data from shallow, evenly distributed krill targets were well correlated with equivalent data from the EK500 ( r 2>0.98), and the offsets between instruments conformed to those predicted for their respective operating frequencies by a theoretical model of sound scattering by krill (H 0: S v 153.6 kHz= S v 120 kHz+2.3 dB, t 0.05(2),155=1.98, t=0.74, P=0.46 ). Data from deeper, more irregularly distributed targets differed significantly ( P<0.001). We conclude that under some ideal, but probably rare, circumstances data from the ADCP can be used to derive biomass estimates. The numerous uncertainties surrounding ADCP calibration and the current practical impossibility for users to monitor system performance should, however, preclude these instruments from being used as a matter of course to determine abundance estimates, a task that we believe should remain firmly within the domain of a well calibrated scientific echo sounder.

Ontogeny of the rabbit's circadian rhythms without an external zeitgeber

We have monitored parturition and different behavioral rhythms of does, the activity of suckling pups and behavioral rhythms of rabbits after weaning until adulthood. All animals were living in continuous light conditions (LL). As a consequence of the free-run of the does parturition, which takes place during the resting period of the animal, occurred at almost any time of the day. The once/day nursing was advanced during the first 7–10 days until it was in synchrony with the time of main activity. The pups significantly anticipated nursing by day 5: the 60 min bin prior to nursing exceeded the 24-h mean by 63 ± 30%. The anticipatory activity (AA) was entrained by an artificial nursing schedule of T = 24 h, the 60 min bin prior to nursing exceeding the 24-h mean by 123 ± 50%. Since AA persisted during a 48 h fast, its phase is controlled endogenously. At weaning behavioral rhythms of rabbits free-ran with a main tau <24 h (average 23:35 ± 17′), period length extending with increasing age. 7 10 animals had an additional component >24 h (average: 24:24 ± 16′) which became increasingly dominant, the components <24 h fading out within 30 days after weaning. Between days 340–350 a stable period length of 24:35 ± 8′ and a consolidation of the circadian rhythms was attained. These results confirm that during the first days of the rabbit's life the circadian system is controlled by a feeding entrainable oscillator, the light entrainable oscillators taking over control later.

Effects of midazolam on sleep disturbances associated with westward and eastward flights: Evidence for directional effects

This double-blind parallel groups study investigated the effects of 7.5 mg midazolam on transient insomnia caused by eastward and westward multiple time zone flights. Three groups of six subjects each were treated with either midazolam or placebo during the first four post-flight nights in both directions. Sleep-wake behavior was monitored throughout the study by actigraphic recordings from the wrist of the non-dominant hand in 1 min bins and by morning questionnaires. The results showed that midazolam significantly lengthened sleep and increased the percentages of bins defined as sleep after the eastward flight. These results are discussed in view of recent findings that short-acting benzodiazepines induced phase shifts in mammalian circadian rhythms.

The Rice Industry in Malaya: 1920–1940. By Ding Eing Tan Soo Hai. No. 2. 60. - A History of Port Swettenham. By Min Bin Jamaladdin. No. 3. 1963. 35. - Fifty Years of the Anglican Church in Singapore Island, 1909–1959. By Loh Keng Aun. No. 4. 1963. 54. - Sarawak, 1941–1957. By Liang Kim Bang. Sarawak in the Early Sixties.

The Rice Industry in Malaya: 1920–1940. By Ding Eing Tan Soo Hai. No. 2. 60. - A History of Port Swettenham. By Min Bin Jamaladdin. No. 3. 1963. 35. - Fifty Years of the Anglican Church in Singapore Island, 1909–1959. By Loh Keng Aun. No. 4. 1963. 54. - Sarawak, 1941–1957. By Liang Kim Bang. Sarawak in the Early Sixties. By Edwin Lee. No. 5. 1964. 65. Singapore: Department of History, University of Singapore. Singapore Studies on Borneo and Malaya. Ed. by K. G. Tregonning. M$5 ea. (paper). - Volume 24 Issue 2