Area and Energy Efficient QCA Based Compact Serial Concatenated Convolutional Code Encoder

Quantum-dot Cellular Automata (QCA) is a transistor-less technology known for its low power consumption and higher clock rate. Serial Concatenated Convolutional Coding (SCCC) encoder is a class of forward error correction. This paper picturizes the implementation of the outer encoder as a (7, 4, 1) Bose Chaudhary Hocquenghem encoder that serves the purpose of burst error correction, a pseudo-random inter-leaver used for permuting of systematic code words and finally the inner encoder which is used for the correction of random errors in QCA. Two different architectures of the SCCC encoder have been proposed and discussed in this study. In the proposed two architectures, the first based on external clock signals whereas the second based on internal clock generation. The sub-blocks outer encoder, pseudo-random inter-leaver and inner encoder of the SCCC encoder are optimized, implemented and simulated using QCADesigner and then integrated to design a compact SCCC encoder. The energy dissipation is computed using QCADesigner-E. The proposed SCCC encoder reduced the total area by 46% and energy dissipation by 50% when compared to the reference SCCC encoder. The proposed encoders are more efficient in terms of cell count, energy dissipation and area occupancy respectively.

GNSS time and frequency transfers through national positioning, navigation and timing infrastructure

GNSS signals have been a practical time transfer tool to realise a Coordinated Universal Time (UTC) and set civilian clocks around the world with respect to this atomic time standard. UTC time scale is maintained by the International Bureau of Weights and Measurements (BIPM) adjusted to be close to a time scale based on the Earth’s rotation. In Thailand, the official atomic time clocks are maintained by the National Institute of Metrology Thailand (NIMT) to produce UTC(NIMT) and Thailand standard time which is always 7 hours ahead of UTC(NIMT) because of the time zone differences between Greenwich and Bangkok. National Positioning, Navigation and Timing (PNT) infrastructure comprises of GNSS geodetic receivers uniformly distributed to continually observe GNSS signals, mainly for geodetic survey applications both real-time and post-processing services. NIMT is involved in order to provide time link to UTC and to determine the characteristics of GNSS receiver internal clocks; namely, fractional frequency offset and frequency stabilities by applying the GNSS time transfer techniques of common-view algorithms. Monitored time differences with respect to UTC(NIMT) are achieved from selected 4 ground stations in different parts of the country with observations of 21 days in order to determine the frequency stability at 1-day and 7-day modes. GNSS standard log files; in RINEX format, at these receivers are transformed into a time transfer standard format; CGGTTS, used to compute the time differences between two stations, the fractional frequency offset and the frequency stability. Averaged fractional frequency offsets are 2.8 × 10 − 13 Hertz/Hertz 2.8\times {10^{-13}}\hspace{2.38387pt}\text{Hertz/Hertz} and computed Allan deviation is around 1.5 × 10 − 13 Hertz/Hertz 1.5\times {10^{-13}}\hspace{2.38387pt}\text{Hertz/Hertz} for an averaging time of 1 day. The comparison of the national time scale and receiver clock offsets of every receivers in this national GNSS PNT infrastructure could be accomplished through common-view time transfer using GNSS satellites to maintain the time link of geodetic active control points to UTC as well as to determine receiver internal clock characteristics.

Perception of Daily Time: Insights from the Fruit Flies

We create mental maps of the space that surrounds us; our brains also compute time—in particular, the time of day. Visual, thermal, social, and other cues tune the clock-like timekeeper. Consequently, the internal clock synchronizes with the external day-night cycles. In fact, daylength itself varies, causing the change of seasons and forcing our brain clock to accommodate layers of plasticity. However, the core of the clock, i.e., its molecular underpinnings, are highly resistant to perturbations, while the way animals adapt to the daily and annual time shows tremendous biological diversity. How can this be achieved? In this review, we will focus on 75 pairs of clock neurons in the Drosophila brain to understand how a small neural network perceives and responds to the time of the day, and the time of the year.

Word Distance Affects Subjective Temporal Distance

The kappa effect is a well-reported phenomenon in which spatial distance between discrete stimuli affects the perception of temporal distance demarcated by the corresponding stimuli. Here, we report a new phenomenon that we propose to designate as the lexical kappa effect in which word distance, a non-magnitude relationship of discrete stimuli that exists in the lexical space of the mental lexicon, affects the perception of temporal distance. A temporal bisection task was used to assess the subjective perception of the time interval demarcated by two successively presented words. Word distance was manipulated by varying the semantic (Experiment 1) or phonological (Experiment 2) similarity between the two words. Results showed that the temporal distance between the two words was perceived to be shorter when the corresponding two words were lexically closer. We explain this effect within the internal clock framework by assuming faster detection of the word that terminated timing when it is preceded by a semantically or phonologically similar word.

Circadian Dysregulation: A Mainstream Mess of the Present World

The physiological systems of humans and other organisms are periodic in nature. One such system is a circadian rhythm, a biological internal clock that is endogenous and entrainable. The circadian rhythm regulates essential functions such as the sleep/wake cycle, hormones, feeding behaviour, metabolism and cell division as well. Due to shift work or jet lag or even irregular sleep, diet, etc., circadian rhythm disorders are one of the most common problems in this century. It is a major factor that can trigger various diseases like depression, lung tumorigenesis, cancer, anxiety, depression and many more. The purpose of this review is to discuss circadian dysregulation and its potential long-term effects in cancer including lung tumor and mental illness including depression, anxiety. Loss of autonomous cells containing Bmal1 and Per2 (the core components of circadian rhythm) will increase growth and metabolism imbalance and increase in c-Myc levels. To treat circadian rhythm disorders, zeitgebers (external cues) should be used to entrain or synchronize the circadian rhythm and sleep phase chronotherapy can also be used.

Biodynamic Lighting Conditions Preserve Nocturnal Melatonin Production in Pregnant Women During Hospitalization: A Randomized Prospective Pilot Study

Maternal circadian rhythms are important for maintaining maternal and fetal homeostasis. The maternal circadian system coordinates the internal clock of the fetus with environmental lighting conditions via the melatonin signal. The intensity and wavelength of daylight influence nocturnal melatonin production. This study aims to evaluate the effect of environmental lighting conditions on melatonin production in pregnant women with reduced mobility during hospitalization. We installed a human-centric lighting system with biodynamic effects (BDL, biodynamic lighting) in the patient rooms. The pregnant women in the patient rooms with standard indoor conditions served as a control group. The illuminance (lux) and dose of effective circadian irradiation (Hec) were recorded every 10 seconds by light dosimeters (Lucerne University, Switzerland) attached to the patients` clothing. We analyzed the illuminance status of 47 pregnant women with a median (IQR) gestational age of 29.9 (25.4-32.3) weeks of gestation. The median illuminance in the control group was significantly lower (p<0.05) than in the BDL group in the morning and afternoon from day 1 to 5. BDL patients had a significantly higher effective circadian irradiation in the morning. The effective circadian irradiation showed a significant daily rhythm only in the BDL group. The BDL group had a significantly higher melatonin production on day 3 (p=0.006) and day 6 (p=0.012) than the control group (median (IQR) 15840 (10140-22160) ng vs. 6141 (2080-11328) ng/n on day 3 and 18780 (11320-23562) ng vs. 6380 (3500-17600) ng on day 6). We have demonstrated that dramatically altered lighting conditions of hospitalized pregnant women may be optimized by installing biodynamic lighting systems in the patient rooms resulting in the maintenance of nocturnal melatonin production in pregnant women.

A Low Energy Clock Network with a Huge Number of Local Synchronized Oscillators

<div>A clock system for a huge grid of small clock regions is presented. There is an oscillator in each clock region, which drives the local clock of a processing element (PE). The oscillators are kept synchronized by exploiting the phase of their neighbors. In an infinite mesh, the clock skew would be zero, but in a network of limited size there will be fringe effects. In a mesh with 25×25 oscillators, the maximum skew between neighboring regions is within 3.3 ps. By slightly adjusting the free running frequency of the oscillators, this skew can be reduced to 1.2 ps. The mesh may contain millions of clock regions.</div><div> Because there is no central clock, both power consumption and clock frequency can be improved compared to a conventional clock distribution network. A PE of 150×150 µm² running at 6.7 GHz with 93 master-slave flip-flops is used as an example. The PE-internal clock skew is less than 2.3 ps, and the energy consumption of the clock system 807 µW per PE. It corresponds to an effective gate and wire capacitance of 509 aF, or 7.3 gate capacitances.</div><div> Power noise is reduced by scheduling the local oscillators gradually along one of the grid’s axes. In this way, surge currents, which generally have their peaks at the clock edges, are distributed evenly over a full clock cycle.</div>

A Low Energy Clock Network with a Huge Number of Local Synchronized Oscillators

<div>A clock system for a huge grid of small clock regions is presented. There is an oscillator in each clock region, which drives the local clock of a processing element (PE). The oscillators are kept synchronized by exploiting the phase of their neighbors. In an infinite mesh, the clock skew would be zero, but in a network of limited size there will be fringe effects. In a mesh with 25×25 oscillators, the maximum skew between neighboring regions is within 3.3 ps. By slightly adjusting the free running frequency of the oscillators, this skew can be reduced to 1.2 ps. The mesh may contain millions of clock regions.</div><div> Because there is no central clock, both power consumption and clock frequency can be improved compared to a conventional clock distribution network. A PE of 150×150 µm² running at 6.7 GHz with 93 master-slave flip-flops is used as an example. The PE-internal clock skew is less than 2.3 ps, and the energy consumption of the clock system 807 µW per PE. It corresponds to an effective gate and wire capacitance of 509 aF, or 7.3 gate capacitances.</div><div> Power noise is reduced by scheduling the local oscillators gradually along one of the grid’s axes. In this way, surge currents, which generally have their peaks at the clock edges, are distributed evenly over a full clock cycle.</div>

Shedding Light on the Circadian Clock of the Threespine Stickleback

The circadian clock is an internal timekeeping system shared by most organisms, and knowledge about its functional importance and evolution in natural environments is still needed. Here, we investigated the circadian clock of wild-caught threespine sticklebacks (Gasterosteus aculeatus) at the behavioural and molecular levels. While their behaviour, ecology, and evolution are well studied, information on their circadian rhythms are scarce. We quantified the daily locomotor activity rhythm under a light-dark cycle (LD) and under constant darkness (DD). Under LD, all fish exhibited significant daily rhythmicity, while under DD, only 18% of individuals remained rhythmic. This interindividual variation suggests that the circadian clock controls activity only in certain individuals. Moreover, under LD, some fish were almost exclusively nocturnal, while others were active around the clock. Furthermore, the most nocturnal fish were also the least active. These results suggest that light masks activity (i.e. suppresses activity without entraining the internal clock) more strongly in some individuals than others. Finally, we quantified the expression of five clock genes in the brain of sticklebacks under DD using qPCR. We did not detect circadian rhythmicity, which could either indicate that the clock molecular oscillator is highly light-dependent, or that there was an oscillation but that we were unable to detect it. Overall, our study suggests that a strong circadian control on behavioural rhythms may not necessarily be advantageous in a natural population of sticklebacks and that the daily phase of activity varies greatly between individuals because of a differential masking effect of light.

Retina-attached slice recording reveals light-triggered tonic GABA signaling in suprachiasmatic nucleus

Light is a powerful external cue modulating the biological rhythm of internal clock neurons in the suprachiasmatic nucleus (SCN). GABA signaling in SCN is critically involved in this process. Both phasic and tonic modes of GABA signaling exist in SCN. Of the two modes, the tonic mode of GABA signaling has been implicated in light-mediated synchrony of SCN neurons. However, modulatory effects of external light on tonic GABA signalling are yet to be explored. Here, we systematically characterized electrophysiological properties of the clock neurons and determined the spatio-temporal profiles of tonic GABA current. Based on the whole-cell patch-clamp recordings from 76 SCN neurons, the cells with large tonic GABA current (>15 pA) were more frequently found in dorsal SCN. Moreover, tonic GABA current in SCN was highly correlated with the frequency of spontaneous inhibitory postsynaptic current (sIPSC), raising a possibility that tonic GABA current is due to spill-over from synaptic release. Interestingly, tonic GABA current was inversely correlated with slice-to-patch time interval, suggesting a critical role of retinal light exposure in intact brain for an induction of tonic GABA current in SCN. To test this possibility, we obtained meticulously prepared retina-attached SCN slices and successfully recorded tonic and phasic GABA signaling in SCN neurons. For the first time, we observed an early-onset, long-lasting tonic GABA current, followed by a slow-onset, short-lasting increase in the phasic GABA frequency, upon direct light-illumination of the attached retina. This result provides the first evidence that external light cue can directly trigger both tonic and phasic GABA signaling in SCN cell. In conclusion, we propose tonic GABA as the key mediator of external light in SCN.