scholarly journals Phase Shift Between Age-Specific COVID-19 Incidence Curves Points to a Potential Epidemic Driver Function of Kids and Juveniles in Germany

2021 ◽  
Author(s):  
Hans H. Diebner
Keyword(s):  
Phase Shift ◽  
Correlation Coefficients ◽  
Phase Shifts ◽  
Negative Phase ◽  
Time Lags ◽  
Age Classes ◽  
Epidemic Dynamics ◽  
Country Level ◽  
Cross Correlations ◽  
Fourth Wave

Mutual phase shifts between three German COVID-19 incidence curves corresponding to the age classes of children, juveniles and adults, respectively, are calculated by means of delay-cross-correlations. At the country level, a phase shift of -5 weeks during the first half of the epidemic between the incidence curves corresponding to the juvenile age class and the curve corresponding to the adult class is observed. The children's incidence curve is shifted by -3 weeks with respect to the adults' curve. On the regional level of the 411 German districts (Landkreise) the distributions of observed time lags are inclined towards negative values. Regarding the incidence time series of the juvenile sub-population, 20% of the German districts exhibit negative phase shifts and only 3% show positive shifts versus the incidence curves of the adult sub-population. Similarly for the children with 6% positive shifts. Thus, children's and juveniles' epidemic activity is ahead of the adults' activity. The correlation coefficients of shifted curves are large (> 0.9 for juveniles versus adults on the country level) which indicates that aside from the phase shift the sub-populations follow a similar epidemic dynamics. Negative phase shifts of the children's incidence curves during the first and second epidemic waves are predictors for high incidences during the current fourth wave with respect to the corresponding districts.

scholarly journals Angle-of-Arrival Estimation Using Difference Beams in Localized Hybrid Arrays

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1901
Author(s):  
Hang Li ◽  
Zhiqun Cheng
Keyword(s):  
Phase Shift ◽  
State Of The Art ◽  
Beam Steering ◽  
Phase Shifts ◽  
The State ◽  
Estimation Accuracy ◽  
Phase Ambiguity ◽  
Angle Of Arrival ◽  
Cross Correlations ◽  
Simulation Results

Angle-of-arrival (AoA) estimation in localized hybrid arrays suffers from phase ambiguity owing to its localized structure and vulnerability to noise. In this letter, we propose a novel phase shift design, allowing each subarray to exploit difference beam steering in two potential AoA directions. This enables the calibration of cross-correlations and an enhanced phase offset estimation between adjacent subarrays. We propose two unambiguous AoA estimation schemes based on the even and odd ratios of the number of antennas per subarray N to the number of different phase shifts per symbol K (i.e., N/K), respectively. The simulation results show that the proposed approach greatly improves the estimation accuracy as compared to the state of the art when the ratio N/K is even.

LONG-RANGE CORRELATIONS IN THE PHASE-SHIFTS OF NUMERICAL SIMULATIONS OF BIOCHEMICAL OSCILLATIONS AND IN EXPERIMENTAL CARDIAC RHYTHMS

1999 ◽  
Vol 07 (02) ◽  
pp. 113-130 ◽  
Author(s):  
I. M. DE LA FUENTE ◽  
L. MARTINEZ ◽  
J. M. AGUIRREGABIRIA ◽  
J. VEGUILLAS ◽  
M. IRIARTE
Keyword(s):  
Phase Shift ◽  
Periodic Solutions ◽  
Long Range ◽  
Phase Shifts ◽  
Long Range Correlations ◽  
Rescaled Range ◽  
Biochemical Oscillations ◽  
Phase Shift Data ◽  
Relationship Of ◽  
The Relationship

In biochemical dynamical systems during each transition between periodical behaviors, all metabolic intermediaries of the system oscillate with the same frequency but with different phase-shifts. We have studied the behavior of phase-shift records obtained from random transitions between periodic solutions of a biochemical dynamical system. The phase-shift data were analyzed by means of Hurst's rescaled range method (introduced by Mandelbrot and Wallis). The results show the existence of persistent behavior: each value of the phase-shift depends not only on the recent transitions, but also on previous ones. In this paper, the different kind of periodic solutions were determined by different small values of the control parameter. It was assessed the significance of this results through extensive Monte Carlo simulations as well as quantifying the long-range correlations. We have also applied this type of analysis on cardiac rhythms, showing a clear persistent behavior. The relationship of the results with the cellular persistence phenomena conditioned by the past, widely evidenced in experimental observations, is discussed.

Student understanding of phase shifts, frequency and Bode plots

2016 ◽  
Vol 54 (3) ◽  
pp. 247-261 ◽  
Author(s):  
Pieter Coppens ◽  
Johan Van den Bossche ◽  
Mieke De Cock
Keyword(s):  
Phase Shift ◽  
Time Domain ◽  
Engineering Students ◽  
Phase Shifts ◽  
Student Understanding ◽  
Bode Plots ◽  
Second Year ◽  
The Time Domain

In a series of interviews with second year electronics engineering students, several of them showed problems with signal properties. In a questionnaire administered to over 150 students in Belgium, these problems were further explored to verify how widespread they are. The questions asked about different aspects of signals. Students showed that they understand the concept of a phase shift, although they have problems with the direction. However, they generally have no idea what a signal with two frequencies looks like in the time domain. Bode plots also proved to be a problem for students, who are not able to construct one from a set of (dummy) measurements. Most of these issues persist after lab instruction.

A HIGHLY ACCURATE ULTRASONIC MEASUREMENT SYSTEM FOR TREMOR USING BINARY AMPLITUDE-SHIFT-KEYING AND PHASE-SHIFT METHOD

2003 ◽  
Vol 15 (02) ◽  
pp. 61-67 ◽  
Author(s):  
MENG-HSIANG YANG ◽  
K. N. HUANG ◽  
C. F. HUANG ◽  
S. S. HUANG ◽  
M. S. YOUNG
Keyword(s):  
Phase Shift ◽  
Measurement System ◽  
Low Cost ◽  
Phase Shifts ◽  
Ultrasonic Waves ◽  
Shift Method ◽  
Narrow Bandwidth ◽  
Shift Keying ◽  
Modulation Signal ◽  
Phase Shift Method

A highly accurate Binary Amplitude-Shift-Keyed (BASK) ultrasonic tremor measurement system for use in isothermal air is developed. In this paper, we present a simple but efficient algorithm based upon phase shifts generated by three ultrasonic waves of different frequencies. By the proposed method, we can conduct larger range measurement than the phase-shift method and also get higher accuracy compared with the time-of-flight (TOF) method. Our microcomputer-based system includes two important parts. One of which is BASK modulation signal generator. The other is a phase meter designed to record and compute the phase shifts of the three different frequencies and the result motion is then sent to either an LCD for display or a PC for calibration. Experiments are done in the laboratory using BASK modulation for the frequencies of 200 Hz and 1 kHz with a 40 kHz carrier. The measurement accuracy of this measurement system in the reported experiments is within +/- 0.98 mm. The main advantages of this ultrasonic tremor measurement system are high resolution, narrow bandwidth requirement, low cost, and easy to be implemented.

Migration of Anionic Species of Radioactive Cobalt through Soil

1989 ◽  
Vol 176 ◽  
Author(s):  
Toshihiko Ohnuki ◽  
David E. Robertson
Keyword(s):  
Concentration Distribution ◽  
Correlation Coefficients ◽  
Ionic Species ◽  
Average Concentration ◽  
Disposal Site ◽  
Retardation Factor ◽  
Laboratory Measurements ◽  
Waste Disposal Site ◽  
Anionic Species ◽  
Cross Correlations

ABSTRACTThe migration of an anionic species of 60Co through soil has been examined utilizing data on the migration of radionuclides leached from an aqueous waste disposal site. Correlation coefficients between concentrations of the anionic species of 60Co and those of the particulate, cationic and non-ionic species of 60Co reveal that the anionic species of 60Co was not interconverted from the other species during migration. The cross correlations of changes in the concentrations of the anionic species of 60Co with time between three different down gradient positions give a calculated retardation factor of the anionic species of 60Co of approximately 19, being 1200 times lower than the results of laboratory measurements. The average concentration distribution of the anionic species of 60Co suggests that the migration of the anionic species of 60Co consists of two migration fractions which were driven by different migration mechanisms.

scholarly journals Estimating time delays for constructing dynamical networks

2014 ◽  
Vol 21 (5) ◽  
pp. 929-937 ◽  
Author(s):  
E. A. Martin ◽  
J. Davidsen
Keyword(s):  
Random Walk ◽  
Time Delays ◽  
Large Time ◽  
Multivariate Time Series ◽  
Time Lag ◽  
Time Lags ◽  
Climate Data ◽  
Dynamical Networks ◽  
Frequency Space ◽  
Cross Correlations

Abstract. Dynamical networks – networks inferred from multivariate time series – have been widely applied to climate data and beyond, resulting in new insights into the underlying dynamics. However, these inferred networks can suffer from biases that need to be accounted for to properly interpret the results. Here, we report on a previously unrecognized bias in the estimate of time delays between nodes in dynamical networks inferred from cross-correlations, a method often used. This bias results in the maximum correlation occurring disproportionately often at large time lags. This is of particular concern in dynamical networks where the large number of possible links necessitates finding the correct time lag in an automated way. We show that this bias can arise due to the similarity of the estimator to a random walk, and are able to map them to each other explicitly for some cases. For the random walk there is an analytical solution for the bias that is closely related to the famous Lévy arcsine distribution, which provides an upper bound in many other cases. Finally, we show that estimating the cross-correlation in frequency space effectively eliminates this bias. Reanalysing large lag links (from a climate network) with this method results in a distribution peaked near zero instead, as well as additional peaks at the originally assigned lag. Links that are reassigned smaller time lags tend to have a smaller distance between them, which indicates that the new time delays are physically reasonable.

scholarly journals Spin-correlation coefficients and phase-shift analysis forp+He3elastic scattering

2010 ◽  
Vol 82 (3) ◽  
Author(s):  
T. V. Daniels ◽  
C. W. Arnold ◽  
J. M. Cesaratto ◽  
T. B. Clegg ◽  
A. H. Couture ◽  
...  
Keyword(s):  
Phase Shift ◽  
Correlation Coefficients ◽  
Spin Correlation ◽  
Phase Shift Analysis ◽  
Shift Analysis

A Radio over Fiber (RoF) Based Single Sideband Modulated Passive Optical Network (PON) Using Mach Zender Modulator Based on Different Electrical Phase Shifts

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Hilal Ahmad Sheikh ◽  
Anurag Sharma
Keyword(s):  
Phase Shift ◽  
Optical Network ◽  
Phase Shifts ◽  
Radio Over Fiber ◽  
Second Order ◽  
Passive Optical Network ◽  
First Order ◽  
Single Sideband ◽  
Hybrid Coupler ◽  
Shift Technique

AbstractThis research work provides an insight on a radio over fiber (RoF) based passive optical network (RoF-PON) utilizing two diverse electrical phase shifts with optical single sideband modulation (OSSB) by exploiting Mach Zender modulator. The influence of chromatic dispersion (CD) in PONs employing single mode fiber (SMF) is a noteworthy issue and should be limited. The two techniques of OSSB modulation, in view of the two distinct angles of the hybrid coupler are employed for the design and implementation of RoF-PON. The RF signal is partitioned into two ways equally before applying it to the dual drive Mach Zender modulator input, utilizing an electrical hybrid coupler that imparts two discrete phase shifts of 90° and 120° to generate two OSSB signals individually. By utilizing traditional OSSB technique having 90° phase shift, either of the first-order sideband (lower or upper first order) suppression occurs yet second-order harmonics are still existent in the system. As opposed to this, the OSSB technique using 120° phase shift causes the suppression of either lower first order and higher second order sideband or vice versa. When contrasted to the PON based on traditional technique (90° phase shift technique), the suppression of second order sideband in PON using 120° technique lessens the system CD. Hence the PON based on 120° phase shift technique has enhanced functionality in terms of system BER, received power and power losses as compared to that with traditional OSSB technique.

Evolution of bubble statistics in intermediate water due to phase shifted breaking wave groups

2021 ◽  
Author(s):  
Konstantinos Chasapis ◽  
Eugeny Buldakov ◽  
Helen Czerski
Keyword(s):  
Phase Shift ◽  
Amplitude Spectrum ◽  
Phase Shifts ◽  
Front Face ◽  
Wave Crest ◽  
Breaking Wave ◽  
Intermediate Water ◽  
Maximum Volume ◽  
Wave Groups ◽  
Single Wave

<p>The bubbles generated by breaking waves in the open ocean are an important feature of the ocean surface. They affect optical and acoustical properties of the top few meters of the ocean, influence surfactant scavenging, aerosol production and air-sea gas transfer. Short-lived larger bubbles which re-surface and burst dominate the transfer of less soluble gases such as carbon dioxide. A single wave crest approaching breaking deforms rapidly and in a storm sea the most common breaker is the spilling type. Detailed observations in space and time connecting the shape of the spilling breaker to subsequent bubble populations are limited, and the effect on the bubble penetration depth and residence time underwater is particularly important. In this study, we carried out a series of experiments to track the formation and evolution of large bubbles for different local crest geometries.</p><p>A breaking wave in a wave flume was generated with dispersive focusing of a wave group. The group has a pre-defined amplitude spectrum. Running experiments with different phase shifts of the same amplitude spectrum showed that when a peak-focussed wave (zero phase shift) breaks, then wave groups with other added phase shifts break as well. To investigate possible differences in the deformation of those breakers a laser imaging technique was used. An algorithm identified the 2D shape of the breaker in successive images. It also separated the crests from bulges based on geometric criteria. We showed that, despite wave groups having same spectra, the extracted bulges differed locally in shape, volume and velocity for each phase shift at the location of breaking. Therefore, breakers ranging from the more traditional spilling type, which has a bulge that collapses on the front face of the wave, to the micro-plunging type, which has a pronounced overturning tip, were observed depending on the phase shift. </p><p>The evolution of bubbles for each phase shifted bulge was captured by a high speed camera and measured by a feature extraction algorithm. We generally found that spilling bulges created fewer bubbles in total than micro-plungers. They also created fewer larger bubbles, i.e. with radius r>1 mm, at all measured flume areas. In contrast, micro-plungers that trap air within a small cavity as they break had less steep size distributions for r>1 mm. The maximum volume of air per radius showed a gradual shift from r>1 mm to r=1 mm moving away from the breaking location for all breakers. It is interesting, finally, that the maximum volume per radius did not shift to smaller radii as time passes. This is an indication that the largest bubbles, i.e. r>4 mm, rise to the surface and burst instead of splitting into smaller ones, irrespectively of the local breaker properties. </p>

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