Clock Shift Research Articles

A Passive-Source Ocean-Bottom Seismic Experiment in the South China Sea: Evaluations of Data Quality and Instrument Performance

Abstract This study presents a passive-source ocean-bottom seismograph (OBS) experiment conducted in the southwest subbasin of the South China Sea (SCS) aimed at exploring the geodynamic processes shaping this short-lived oceanic basin. The successful deployment and recovery of 24 passive-source OBS units, including 14 I-7C types and 10 Pankun OBS units, resulted in the acquisition of one of the most extensive passive-source seismic data sets ever recorded in the SCS. We provide comprehensive details of the experiment, with a focus on evaluating the data quality and performance of the Pankun OBS units. This evaluation includes assessments of horizontal orientation determination, leveling system effectiveness, timing accuracy, and ambient noise spectrum. In addition, we compared the waveforms recorded by the Pankun OBS units with those from land stations and I-7C units, as well as the noise spectra between Pankun and global OBSs using the same seismometer. Although these comparisons suggest that the Pankun OBS achieves satisfactory performance, we identified a few inadequacies with this new instrument, such as issues with the differential pressure gauge, clock shifts, and sensor package calibration.

Considering the impact of shift working on health.

Shift work is necessary for the provision of health services, especially in hospitals as it is the only way to provide continuous care to patients. Working at night is inconsistent with the body's biological clock and night shift working hugely disrupts the circadian and sleep wake cycles. In 2020, the World Health Organization classified night shift working as being a 'probable' class 2A carcinogen and a number of independent cohort studies of both night workers and shift workers have observed increased incidence of certain cancers. Altered sleep timing, food timing and light exposure typical for shift workers leads to an acute circadian disruption and misalignment of regulatory hormones. This straying from synchronisation has been shown to result in individuals being more vulnerable to a number of chronic health conditions. Night shift work disrupts the normal sleep-wake cycle, often leading to shortened sleep duration and excessive fatigue and the results of this are far reaching. This article will explore the full impact of shift working, questioning if current practices employed within the NHS should continue.

A novel reduced instruction set computer-communication processor design using field programmable gate array

In this paper, a novel reduced instruction set computer (RISC)- communication processor (RCP) has been designed with 32-bit operations which access 64-bit instruction format and implemented using field programmable gate array (FPGA). The design of the RISC processor is facilitated with communication operations like basic signals sine, cosine, and square, and modulation schemes like amplitude modulation, amplitude shift keying, analog, and digital quadrature amplitude modulation. Additionally, application-oriented operations like a traffic light, digital clock, and linear feedback shift register are included in the design. The pipeline mechanism is incorporated in the design to enhance the performance characteristics of the processor, hence allowing the execution of the instructions more effectively. Also, the design is implemented with Xilinx Virtex 7 family FPGA. The device utilization analysis of the proposed FPGA along with different FPGA families is evaluated and compared.

Constraining fundamental constant variations from ultralight dark matter with pulsar timing arrays

Pulsar Timing Arrays (PTAs) are exceptionally sensitive detectors in the frequency band $\text{nHz} \lesssim f \lesssim \mu\text{Hz}$. Ultralight dark matter (ULDM), with mass in the range $10^{-23}\,\text{eV} \lesssim m_\phi \lesssim 10^{-20}\,\text{eV}$, is one class of DM models known to generate signals in this frequency window. While purely gravitational signatures of ULDM have been studied previously, in this work we consider two signals in PTAs which arise in presence of direct couplings between ULDM and ordinary matter. These couplings induce variations in fundamental constants, i.e., particle masses and couplings. These variations can alter the moment of inertia of pulsars, inducing pulsar spin fluctuations via conservation of angular momentum, or induce apparent timing residuals due to reference clock shifts. By using mock data mimicking current PTA datasets, we show that PTA experiments outperform torsion balance and atomic clock constraints for ULDM coupled to electrons, muons, or gluons. In the case of coupling to quarks or photons, we find that PTAs and atomic clocks set similar constraints. Additionally, we discuss how future PTAs can further improve these constraints, and detail the unique properties of these signals relative to the previously studied effects of ULDM on PTAs.

Relationship Between Daylight Saving Time and Traffic Crashes in Florida

The objective of this study was to examine the effect of transitions between daylight saving time (DST) and standard time (ST) on traffic crashes in Florida. The study was conducted using 37 years of crash data from Florida from 1983 to 2019. The analysis was based on crashes that occurred during the week before and the week following the time change. The paired Wilcoxon rank test implemented using a Bayesian approach was used to compare the difference in crash frequency following the clock shift to DST. The analysis showed that the time shift has a significant effect on traffic crashes. More specifically, the beginning of DST in the spring, when the clock moves forward by one hour, was associated with a higher frequency of fatal and nighttime crashes. The shift at the end of DST in the fall, when the clock moves back by one hour, resulted in a significant increase in all, no injury, morning peak hours, afternoon off-peak hours, two-vehicle, and multiple-vehicle crashes. Crashes during evening peak hours decreased in the week immediately following the time change. These findings were particularly significant on the Sunday when the shift occurred and the following Monday and Tuesday. It can be inferred from these findings that the impact of DST on safety may be attributed to the disruption of circadian rhythms as well as to the one-hour loss in the spring and one-hour gain in the fall. The study findings could assist researchers and practitioners in understanding the impacts of DST on roadway safety.

Integrated molecular and behavioural data reveal deep circadian disruption in response to artificial light at night in male Great tits (Parus major)

Globally increasing levels of artificial light at night (ALAN) are associated with shifting rhythms of behaviour in many wild species. However, it is unclear whether changes in behavioural timing are paralleled by consistent shifts in the molecular clock and its associated physiological pathways. Inconsistent shifts between behavioural and molecular rhythms, and between different tissues and physiological systems, disrupt the circadian system, which coordinates all major body functions. We therefore compared behavioural, transcriptional and metabolomic responses of captive great tits (Parus major) to three ALAN intensities or to dark nights, recording activity and sampling brain, liver, spleen and blood at mid-day and midnight. ALAN advanced wake-up time, and this shift was paralleled by advanced expression of the clock gene BMAL1 in all tissues, suggesting close links between behaviour and clock gene expression across tissues. However, further analysis of gene expression and metabolites revealed that clock shifts were inconsistent across physiological systems. Untargeted metabolomic profiling showed that only 9.7% of the 755 analysed metabolites followed the behavioural shift. This high level of desynchronization indicates that ALAN disrupted the circadian system on a deep, easily overlooked level. Thus, circadian disruption could be a key mediator of health impacts of ALAN on wild animals.

Design and Construction of a Smart-home Automation System (SHAS) using Nodemcu and Google Assistant

This paper presents the design and construction of a smart-home automation system using nodeMCU and Google assistant. The device consist of Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) module that contains all clock generators, shift registers and data buffers necessary to perform an input or output serial data transfer independently of the device program execution. The NodeMCU (ESP8266) Wi-fi Shield connected the microcontroller to the provided Wi-fi network. The Arduino and MPLAB Programming Interface with the help of PICKit3 were used to run the code on PIC16F877A. Home appliances were controlled via a web page created using IFTTT for the voice command and the Blynk app for controlling hardware remotely and also display sensor data. IFTTT is a simple to use internet service that easily enables IoT devices to GET and POST data. The device was constructed based on low cost and reliable home controlled monitoring system for accessing and controlling electronics appliances remotely using any Smart phone with access to Google assistance or Computer web application. The device was test under different electronics appliances with different voltage capacities and was found efficient. Therefore, this device when used is capable of improving the living standard at home, reduces human effort, save energy and time thus make homes have sufficient automation.

Effect of Daylight Saving Time clock shifts on white-tailed deer-vehicle collision rates

To devise effective measures for reducing hazardous wildlife-vehicle collisions, it is necessary to know when during the year accidents occur most frequently, and what factors cause the seasonal patterns. Daylight Saving Time (DST) 1-h clock-shifts around the spring and fall equinoxes at temperate zone latitudes are associated with increased vehicle accidents, attributed to driver error caused by disrupted sleep patterns and changes in visibility during peak driving times. Collision with deer is a significant cause of motor vehicle accidents in North America; in New York State alone, 65,000 vehicle accidents annually are caused by collision with white-tailed deer (Odocoileus virginianus). We asked whether white-tailed deer-vehicle collisions (DVC) increased in frequency after DST clock shifts in New York State, by analyzing 35,167 New York State DVC reports from 2005 to 2007. For the spring, when the clock is shifted an hour forward relative to sunrise (i.e. later sunrise and sunset), there was either no change or possibly a small decrease in workweek evening DVC after the clock shift. For fall, when the clock is shifted an hour back relative to sunrise (i.e. earlier sunrise and sunset), the DVC rate was far higher than spring. The DVC rate was higher after the clock shift than before, caused in part by an ongoing seasonal trend for increasing DVC associated with deer behavior around the time of rut, peaking about two weeks after the clock shift. However, there was also a reduction in workweek morning DVC after clock-shift, but an even greater increase in DVC in the evening. DVC rates are highest around dusk and during the fall, and the fall DST clock-shift caused more workweek commuter traffic to coincide with the annual hourly period of peak risk of DVC. We conclude that in New York State, DST clock-shift results in an increase in the number of DVC, and therefore injuries and property damage associated with such accidents. The justification for DST clock-shifts is controversial; when evaluating the benefits and costs, one should include the consequences for risk of wildlife-vehicle collisions, especially in regions where ungulate-vehicle accidents are frequent, and clock-shifts coincide with the rut or other periods of peak accident risk.

Collision clock shift of two Fermi atoms in harmonic potentials

Atomic clocks provide the most accurate definition for time. The precision of atomic clock has been improved by many orders of magnitude since the first atomic clock was built. However, the interatomic interaction usually suppress the precision of atomic clock. As a result, it is especially meaningful to study the interaction effect in atomic clock, which is considered to be helpful in improving the precision and accuracy of atomic clock. In order to characterize the collision effect induced clock shift, we theoretically study the collision clock shift in the Rabi spectrum, caused by the short-range interaction between two Fermi atoms in harmonic potential. Given that the short-range interatomic interaction is generally weak, and that the parameters of external lattice laser field are in the Lamb-Dicke regime, we make an approximation that the spatial wave-function of the Fermi atoms does not change, and then derive the motion equation for the internal wave-function under the external Rabi driving field. We solve the equation of motion by the perturbative method, and obtain the solution to first order, and thus derive the expression of the collision clock shift of the Rabi spectrum in terms of the interatomic interaction and the external Rabi driving laser field parameters for specific spatial wave-functions of atoms. Finally, we use the exact expression of the Green’s function in harmonic potential to obtain the averaged clock shift of collision at finite temperatures. Our results relate the atomic interaction with atomic clock shift, and provide a unified description of all partial waves of atomic interaction induced clock shift. Therefore, it becomes much more convenient to study the contributions of different partial waves to atomic clock shift. On the other hand, our results indicate that through precisely measuring the clock shift, the information about the interatomic interactions can also be obtained. In addition, our results for two interacting atoms can inspire the future study of real many-body interacting system which will be the next research topic.

ФАКТОРЫ РИСКА ХРОНИЧЕСКИХ НЕИНФЕКЦИОННЫХ ЗАБОЛЕВАНИЙ У СОТРУДНИКОВ МИНИСТЕРСТВА ЧРЕЗВЫЧАЙНЫХ СИТУАЦИЙ

Objective: To establish risk factors (RFs) for the development of noncommunicable diseases (NCDs) among the Ministry of Emergency Situations (MChS) personnel. Methods: To identify the RFs for the development of NCDs, the health status of 205 MChS staff members of the Udmurt Republic, Russia, was assessed by a social survey according to a specially developed form «Social and hygienic profile of the MChS employee». In addition, the method of regression analysis, multiple linear regression, was selected to identify risk factors for NCDs. Results: Regression analysis showed that the MChS personnel health status is influenced in decreasing order by socio-hygienic, medico-biological, and professional factors. At the same time, the development of NCDs was significantly influenced by the complex of all identified RFs (R2=0.69; F=4.93; p=0.0001). The following statistically significant RFs for the development of chronic diseases in the MChS personnel were identified: work exposure of 6 years or more; frequent round the clock shifts; smoking; negative family emotional climate; a high level of state and trait anxiety, age 33 and above, and passive recreational use. Failure to maintain a healthy lifestyle (HL) is referred to as «borderline» RF. Conclusion: The identified RFs will promote development of the programs of NCDs prevention among the MChS personnel. Particular attention should be paid to educational technologies promoting health-related activities and good hygiene practices when developing programs. Keywords: Risk factors , chronic noncommunicable diseases, an employee of the Ministry of Emergency Situations.

Driving circuitry of a full-frame area array charge-coupled device (CCD) supporting multiple output modes and electronic image motion compensation

In order to design a charge-coupled device (CCD) driving circuit with a high frame rate and a large area array which can support the electronic image motion compensation function, first a basic driving circuit of the large-array CCD is reported in this paper. Next, electronic image motion compensation is realized by adding an image motion compensation timing generator and a main timing generator, Saa8103. The internal design structure of the image motion compensation generator is provided and is characterized as follows. The data are first sent by the system controller, the main timing generator and the image motion compensation timing generator. The generator, the vertical driver, the horizontal driver and the full-frame charge-coupled device chip are then composed. During the exposure period, the image motion compensation transfer clock is generated by the image motion compensation timing generator, and the charge-coupled device charge packet is driven to track the image movement after being amplified by the vertical and horizontal drivers to carry out electronic image motion compensation in the vertical direction. During the output period, the vertical and horizontal rotations generated by the main timing generator are carried out by the image motion compensation timing generator. The shift clock is transmitted to the vertical and horizontal drivers to drive the charge-coupled device to produce the output. The phase relationship of the four corners of the charge-coupled device is independently controlled by the image motion compensation timing generator, which supports not only the electronic image motion compensation but also the flexible selection of the output channel number and output mode. A field-programable gate array (FPGA)/complex programable logic device (CPLD) has been selected to be the timing generator of image motion compensation, and timing simulation is carried out. Lastly, the design of the driving circuit was verified by an indoor image motion compensation experiment, and a good compensation effect has been achieved. In this system, the charge-coupled device adopts a separate driving technology, and the charge transfer direction of each block can be established. Consequently, it is convenient to select the number of output channels and the output mode, which makes the camera suitable for different occasions, supports the charge-coupled device in terms of the output and electronic image motion compensation in various ways, and is capable of generating full-frame images. In order to meet the different requirements regarding the charge-coupled device frame frequency in different contexts, this proposed design overcomes the disadvantages of the complex structure and low reliability of traditional optical mechanical image motion compensation systems.

Simple Timing Signal Analysis Device-XY Mode Displays the Multichannel Shift Waveform

We designed and implemented a simple timing signal analysis device, which displayed multichannel shift waveform without overlapping from left to right on the Oscilloscope screen using X-Y mode as signal input. In order to meet the requirements of high speed sampling rate, we took microcontroller STM32F407VGT6 to collect, storage, analysis signal, and calculate the result wave though high speed DA conversion module to display on the Oscilloscope screen. we took microcontroller STM32F103RB to realize the shift clock circuit and 8-channel digital signal, and adopt the dial-code switch presents the 8-bit trigger word TW. after several test, the signal analysis device could realize the trigger time position adjust at all, time marker line be shifted manually, LED light displayed the status word corresponding to the flag line, and playback two shift cycle timing waveform and other functions simply and efficient. through numerical simulation and experimental analysis, we found that this simple device can greatly display multichannel shift waveform easily and precisely.

Rabi spectroscopy of three-dimensional optical lattice clocks

Recent realisation of three-dimensional optical lattice clocks circumvents short range collisional clock shifts which have been the bottle neck towards higher precision; the long range electronic dipole-dipole interaction between the atoms becomes the primary source of clock shift due to interatomic interactions. We study the Rabi spectroscopy of three-dimensional optical lattice clocks with unity filling. From the Lindblad equation governing the time evolution of the density matrix of the atoms, we derive the Bloch equations in the presence of the external Rabi driving laser field, and solve the equations approximately to the first order of the coupling strength of the dipole-dipole interaction between the atoms. We find that the clock shift equals to the product of the coupling strength, a factor determined by the parameters of the Rabi pulse, and another factor depending on the configuration of the three-dimensional optical lattice. Our result on the clock shift within the Rabi spectroscopy can be checked by measurement in future experiment.

Blackbody radiation shift for the optical clock transition in zinc and cadmium atoms

Black-body radiation (BBR) shifts of the 1S0–3P0 clock transition in divalent atoms Cd and Zn are evaluated using accurate relativistic many-body techniques of atomic structure. Static polarizabilities of the clock levels and relevant electric-dipole matrix elements are computed. We also present a comparative overview of the BBR shifts in optical clocks based on neutral divalent atoms trapped in optical lattices. Zinc and cadmium atoms have one of the smallest BBR clock shifts, mitigating the largest inaccuracy in optical lattice clocks.

By the Light of Day: The Effect of the Switch to Winter Time on Stock Markets

We studied the effect of the end of Daylight Saving Time (DST) on stock markets around the globe. Using a detailed cross-country daily returns data set we found that (a) market returns on the day following the clock shift were significantly lower than the corresponding day of a week unaffected by the change; (b) the economic magnitude of the effect was substantial and averaged 5 – 6 times larger than the unconditional mean of market returns; and (c) the outcome was more prominent in local, relatively small markets. Furthermore, we attempted to identify the underlying mechanism of the gloomy market returns accompanying the switch to winter time. We found (a) no association between market returns and stock market geographic latitude, and (b) that the effect faded out almost immediately. These results — which are consistent with the literature on the human circadian system (which keeps us in sync with the 24-hour day) — suggest that the mechanism underlying the effect may be based on evanescent loss of investor internal clock harmony.

Smith-Magenis Syndrome: Molecular Basis of a Genetic-Driven Melatonin Circadian Secretion Disorder.

Smith-Magenis syndrome (SMS), linked to Retinoic Acid Induced (RAI1) haploinsufficiency, is a unique model of the inversion of circadian melatonin secretion. In this regard, this model is a formidable approach to better understand circadian melatonin secretion cycle disorders and the role of the RAI1 gene in this cycle. Sleep-wake cycle disorders in SMS include sleep maintenance disorders with a phase advance and intense sleepiness around noon. These disorders have been linked to a general disturbance of sleep-wake rhythm and coexist with inverted secretion of melatonin. The exact mechanism underlying the inversion of circadian melatonin secretion in SMS has rarely been discussed. We suggest three hypotheses that could account for the inversion of circadian melatonin secretion and discuss them. First, inversion of the circadian melatonin secretion rhythm could be linked to alterations in light signal transduction. Second, this inversion could imply global misalignment of the circadian system. Third, the inversion is not linked to a global circadian clock shift but rather to a specific impairment in the melatonin secretion pathway between the suprachiasmatic nuclei (SCN) and pinealocytes. The development of diurnal SMS animal models that produce melatonin appears to be an indispensable step to further understand the molecular basis of the circadian melatonin secretion rhythm.

Chip-Scale Terahertz Carbonyl Sulfide Clock: An Overview and Recent Studies on Long-Term Frequency Stability of OCS Transitions

This paper reviews the recent innovations of a miniature time-keeping device with high affordability: chip-scale molecular clock. It is based on the recent research progress of high-precision terahertz (THz) rotational spectrometers, especially those using CMOS integrated circuit technologies. The clock probes the rotational modes of carbonyl sulfide ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</sup> O <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> C <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">32</sup> S) molecule gas and then calibrates its MHz output according to the measured terahertz transition frequency of OCS. In contrast to cesium/rubidium atomic clocks, the THz OCS clock has fully electronic operations and, hence, a significantly simplified implementation. In particular, it is realizable on a waveguide-attached CMOS chip, which minimizes the form factor and cost. Based on a lab scale prototype with an Allan deviation in the 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> range, this paper for the first time studies two critical metrics related to the long-term stability of THz OCS clocks. These metrics are the clock sensitivities to temperature change of the OCS gas and external magnetic field. The measured average temperature coefficient of the clock, without ovenized temperature stabilization and temperature compensation, is 9.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> /°C in the range of 28 °C-70 °C. Next, the measured clock shift in response to a 75 G external magnetic field is <;4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> , with a theoretical value near 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-13</sup> . Lastly, this paper also reviews the first reported CMOS prototype of the clock, which consumes only 66 mW dc power and achieves an Allan deviation of 3.8 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> (τ = 1000 s). Approaches for performance improvements and potential monolithic chip implementation are discussed. These studies present the feasibility of a CMOS-based magnetic-shield/heater-free clock with high energy efficiency and sub-ppb stability over a wide range of operation condition.

Oscillating quadrupole effects in high-precision metrology

The influence of oscillating quadrupole fields on atomic energy levels is examined theoretically and general expressions for the quadrupole matrix elements are given. The results are relevant to any ion-based clock in which one of the clock states supports a quadrupole moment. Clock shifts are estimated for $^{176}$Lu$^+$ and indicate that coupling to the quadrupole field would not be a limitation to clock accuracy at the $\lesssim10^{-19}$ level. Nevertheless, a method is suggested that would allow this shift to be calibrated. This method utilises a resonant quadrupole coupling that enables the quadrupole moment of the atom to be measured. A proof-of-principle demonstration is given using $^{138}$Ba$^+$, in which the quadrupole moment of the $D_{5/2}$ state is estimated to be $\Theta=3.229(89) e a_0^2$.

In Situ Clock Shift Reveals that the Sun Compass Contributes to Orientation in a Pelagic Seabird

Compass orientation is central to the control of animal movement from the scale of local food-caching movements around a familiar area in parids [1] and corvids [2, 3] to the first autumn vector navigation of songbirds embarking on long-distance migration [4-6]. In the study of diurnal birds, where the homing pigeon, Columba livia, has been the main model, a time-compensated sun compass [7] is central to the two-step map-and-compass process of navigation from unfamiliar places, as well as guiding movement via a representation of familiar area landmarks [8-12]. However, its use by an actively navigating wild bird is yet to be shown. By phase shifting an animal's endogenous clock, known as clock-shifting [13-15], sun-compass use can be demonstrated when the animal incorrectly consults the sun's azimuthal position while homing after experimental displacement [15-17]. By applying clock-shift techniques at the nest of a wild bird during natural incubation, we show here that an oceanic navigator-the Manx shearwater, Puffinus puffinus-incorporates information from a time-compensated sun compass during homeward guidance to the breeding colony after displacement. Consistently with homing pigeons navigating within their familiar area [8, 9, 11, 18], we find that the effect of clock shift, while statistically robust, is partial in nature, possibly indicating the incorporation of guidance from landmarks into movement decisions.

Simple analysis of daylight saving time effects in Belgrade climate and latitude

Contemporary controversy about daylight saving time (DST) is mainly derived from different standpoints in studies investigating the positive and negative effects of the clock shift during summer period. From the standpoint of energy savings, most studies have consensus that the summertime clock shift in middle latitudes, with a large difference between winter and summer daylight hours, contributes to energy savings in buildings. Belgrade?s mid-latitude, moderate-continental climate has a six-month long heating season and a three-month cooling season. The annual domination of the heating period assumes that the demand for heating energy also dominates in the annual energy breakdown for average office buildings. Since DST covers mainly summer time, the energy breakdown in office buildings during the DST period is dominated by the energy demand for lighting and cooling. The shift of time ahead of standard time during the DST period causes a shift in temperature, daylight availability and solar energy resources and thus a shift in the potential for the utilisation of the surrounding energy. This paper investigates how the application of DST in Belgrade?s climate and latitude influences the change of climate parameters relevant for the cooling and lighting energy demand in office buildings.