scholarly journals Analysis of SARS-CoV-2 mutations reveals three types of temporal dynamics and one is correlated with international travels

2021 ◽  
Author(s):  
Santiago Justo Arevalo ◽  
Daniela Zapata Sifuentes ◽  
Cesar J. Huallpa ◽  
Gianfranco Landa Bianchi ◽  
Adriana Castillo Chavez ◽  
...  
Keyword(s):  
High Frequency ◽  
Relative Frequency ◽  
Temporal Dynamics ◽  
Low Frequency ◽  
Frequency Change ◽  
Medium Frequency ◽  
Human Behaviors ◽  
Viral Adaptation ◽  
Mutation Dynamics

Coronavirus disease 2019 (COVID-19) is a contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This disease has spread globally, causing more than 161.5 million cases and 3.3 million deaths. Keeping on the identification, surveillance and the study of the temporal dynamics of mutations with significant representation is central to understand the adaptation of SARS-CoV-2. Furthermore, how lockdown policies influence the dynamics of SARS-CoV-2 mutations is poorly understood. Here, using 1 058 020 SARS-CoV-2 genomes and COVID-19 cases from 714 country-month combinations representing 98 countries, we performed a normalization by COVID-19 cases calculation of relative frequency of SARS-CoV-2 mutations. We found 115 mutations estimated to be present in more than 3 % of global COVID-19 cases and determined three types of mutation dynamics: High-Frequency, Medium-Frequency, and Low-Frequency. Classification of mutations based on temporal dynamics helps to study viral adaptation and can be used to evaluate the effects of human behaviors in the pandemic. For instance, we report a negative and positive correlation of the frequency change of High-Frequency mutations with the level of international movement controls and the number of flight departures, respectively.

scholarly journals Dynamics of SARS-CoV-2 mutations reveals regional-specificity and similar trends of N501 and high-frequency mutation N501Y in different levels of control measures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Santiago Justo Arevalo ◽  
Daniela Zapata Sifuentes ◽  
César J. Huallpa ◽  
Gianfranco Landa Bianchi ◽  
Adriana Castillo Chávez ◽  
...  
Keyword(s):  
High Frequency ◽  
Temporal Dynamics ◽  
Control Measure ◽  
Low Frequency ◽  
Virus Genome ◽  
Control Measures ◽  
Medium Frequency ◽  
Viral Adaptation ◽  
Regional Specificity ◽  
Different Levels

AbstractCoronavirus disease 2019 (COVID-19) is a contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This disease has spread globally, causing more than 161.5 million cases and 3.3 million deaths to date. Surveillance and monitoring of new mutations in the virus’ genome are crucial to our understanding of the adaptation of SARS-CoV-2. Moreover, how the temporal dynamics of these mutations is influenced by control measures and non-pharmaceutical interventions (NPIs) is poorly understood. Using 1,058,020 SARS-CoV-2 from sequenced COVID-19 cases from 98 countries (totaling 714 country-month combinations), we perform a normalization by COVID-19 cases to calculate the relative frequency of SARS-CoV-2 mutations and explore their dynamics over time. We found 115 mutations estimated to be present in more than 3% of global COVID-19 cases and determined three types of mutation dynamics: high-frequency, medium-frequency, and low-frequency. Classification of mutations based on temporal dynamics enable us to examine viral adaptation and evaluate the effects of implemented control measures in virus evolution during the pandemic. We showed that medium-frequency mutations are characterized by high prevalence in specific regions and/or in constant competition with other mutations in several regions. Finally, taking N501Y mutation as representative of high-frequency mutations, we showed that level of control measure stringency negatively correlates with the effective reproduction number of SARS-CoV-2 with high-frequency or not-high-frequency and both follows similar trends in different levels of stringency.

Dynamics of the processes in metal machining

1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Cutting Machine ◽  
Metal Machining

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.

How word frequency affects morphological processing in monolinguals and bilinguals

2003 ◽  
Vol 6 (3) ◽  
pp. 213-225 ◽  
Author(s):  
MINNA LEHTONEN ◽  
MATTI LAINE
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Morphological Processing ◽  
Decision Task ◽  
Frequency Range ◽  
Medium Frequency ◽  
Word Forms ◽  
Full Form ◽  
Differential Pattern ◽  
Complex Words

The present study investigated processing of morphologically complex words in three different frequency ranges in monolingual Finnish speakers and Finnish-Swedish bilinguals. By employing a visual lexical decision task, we found a differential pattern of results in monolinguals vs. bilinguals. Monolingual Finns seemed to process low frequency and medium frequency inflected Finnish nouns mostly by morpheme-based recognition but high frequency inflected nouns through full-form representations. In contrast, bilinguals demonstrated a processing delay for all inflections throughout the whole frequency range, suggesting decomposition for all inflected targets. This may reflect different amounts of exposure to the word forms in the two groups. Inflected word forms that are encountered very frequently will acquire full-form representations, which saves processing time. However, with the lower rates of exposure, which characterize bilingual individuals, full-form representations do not start to develop.

Dissociating early and late visual processing via the Ebbinghaus illusion

2016 ◽  
Vol 33 ◽  
Author(s):  
FILIPP SCHMIDT ◽  
ANDREAS WEBER ◽  
ANKE HABERKAMP
Keyword(s):  
Visual Processing ◽  
High Frequency ◽  
Time Course ◽  
Temporal Dynamics ◽  
Low Frequency ◽  
Response Speed ◽  
Ebbinghaus Illusion ◽  
Priming Effects ◽  
Parvocellular Pathway ◽  
The Difference

AbstractVisual perception is not instantaneous; the perceptual representation of our environment builds up over time. This can strongly affect our responses to visual stimuli. Here, we study the temporal dynamics of visual processing by analyzing the time course of priming effects induced by the well-known Ebbinghaus illusion. In slower responses, Ebbinghaus primes produce effects in accordance with their perceptual appearance. However, in fast responses, these effects are reversed. We argue that this dissociation originates from the difference between early feedforward-mediated gist of the scene processing and later feedback-mediated more elaborate processing. Indeed, our findings are well explained by the differences between low-frequency representations mediated by the fast magnocellular pathway and high-frequency representations mediated by the slower parvocellular pathway. Our results demonstrate the potentially dramatic effect of response speed on the perception of visual illusions specifically and on our actions in response to objects in our visual environment generally.

Response selectivity for multiple dimensions of frequency sweeps in the pallid bat inferior colliculus

1994 ◽  
Vol 72 (3) ◽  
pp. 1061-1079 ◽  
Author(s):  
Z. M. Fuzessery
Keyword(s):  
Inferior Colliculus ◽  
High Frequency ◽  
Low Frequency ◽  
Central Nucleus ◽  
Frequency Change ◽  
Frequency Range ◽  
Low Frequencies ◽  
Response Properties ◽  
Sweep Direction ◽  
Pallid Bat

1. While hunting, the pallid bat uses passive sound localization at low frequencies to find terrestrial prey, and echolocation for general orientation. It must therefore process two different types of acoustic input at the same time. The pallid bat's echolocation pulse is a downward frequency-modulated (FM) sweep from 60 to 30 kHz. This study examined the response selectivity of single neurons in the pallid bat's central nucleus of the inferior colliculus (ICC) for FM sweeps, comparing the response properties of the high-frequency population, tuned to the biosonar pulse, with the low-frequency population, tuned below the pulse. The working hypothesis was that the high-frequency population would exhibit a response selectivity for downward FM sweeps that was not present in the low-frequency population. 2. Neurons were tested for their selectivity for FM sweep direction, duration, frequency range and bandwidth, and rate of frequency change. The extent to which they responded exclusively to tones, noise, and FM sweeps was also examined. Significant differences in the response properties of neurons in the two populations were found. In the low-frequency population, all neurons responded to tones, but only 50% responded to FM sweeps. Only 23% were selective for sweep direction. In the high-frequency population, all neurons responded to FM sweeps, but 31% did not respond to tones. Over one-half of this population was selective for sweep direction, and of those that were selective, all preferred the downward sweep direction of the biosonar pulse. A large percentage (31%) responded exclusively to downward sweeps, and not to tones or upward sweeps. None of the cells in either population responded to noise, or did so only at very high relative thresholds. 3. Both populations contained neurons that were selective for short stimulus durations that approximated the duration of the biosonar pulse, although the percentage was greater in the high-frequency population (58% vs. 20%). In the high-frequency population, 31% of the neurons tested for duration responded exclusively to both the sweep direction and duration of the biosonar pulse. 4. Downward FM-selective neurons, with one exception, were generally insensitive to the rate of frequency change of the FM sweep, as well as the frequency range and bandwidth of the sweep. They responded similarly to both the full 60- to 30-kHz sweep and to 5-kHz bandwidth portions of the full sweep.(ABSTRACT TRUNCATED AT 400 WORDS)

Regulation of an ovulatory cycle

1998 ◽  
Vol 2 ◽  
pp. 107-114 ◽  
Author(s):  
D. Švitra ◽  
R. Grigolienė ◽  
A. Puidokaitė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Ovulatory Cycle ◽  
Cutting Machine

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.

Search Time as a Function of Context Letter Frequency

Perception ◽  
1972 ◽  
Vol 1 (1) ◽  
pp. 57-71 ◽  
Author(s):  
C R Latimer
Keyword(s):  
Pattern Recognition ◽  
Reaction Time ◽  
High Frequency ◽  
Relative Frequency ◽  
Search Time ◽  
Low Frequency ◽  
Frequency Of Occurrence ◽  
Template Model ◽  
Letter Frequency ◽  
Feature Frequency

Neisser (1967) posits the operation of purely feature analytic processes in the scanning of context letters in search lists. This contention was tested by varying the relative frequency of occurrence in English of the context letters in alphanumeric search lists, while holding their feature content constant. It was hypothesized that faster search time on lists of high-frequency context letters would indicate letter-level processing. Equality of search time would indicate the purely feature-level processing required by Neisser's theory. Context letters were segregated into high- and low-frequency sets and their features defined and held constant according to two feature analyses. This yielded a 2 × 2 design with 22 subjects per condition. Attention was given to the control of feature frequency, size of the context-letter set, and approximation of English at the level of bigram, trigram, and word. Results supported a letter level or template model of processing but were shown also to be explainable in terms of some feature-testing models of pattern recognition. Apparatus which allowed for the removal of reaction time in search lists is described.

scholarly journals Motoneuron firing patterns underlying fast oscillations in phrenic nerve discharge in the rat

2012 ◽  
Vol 108 (8) ◽  
pp. 2134-2143 ◽  
Author(s):  
Vitaliy Marchenko ◽  
Michael G. Z. Ghali ◽  
Robert F. Rogers
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Medium Frequency ◽  
Adult Rats ◽  
Time Frequency ◽  
High Frequency Oscillations ◽  
Novel Method ◽  
Frequency Coherence ◽  
Fast Oscillations ◽  
First Time

Fast oscillations are ubiquitous throughout the mammalian central nervous system and are especially prominent in respiratory motor outputs, including the phrenic nerves (PhNs). Some investigators have argued for an epiphenomenological basis for PhN high-frequency oscillations because phrenic motoneurons (PhMNs) firing at these same frequencies have never been recorded, although their existence has never been tested systematically. Experiments were performed on 18 paralyzed, unanesthetized, decerebrate adult rats in which whole PhN and individual PhMN activity were recorded. A novel method for evaluating unit-nerve time-frequency coherence was applied to PhMN and PhN recordings. PhMNs were classified according to their maximal firing rate as high, medium, and low frequency, corresponding to the analogous bands in PhN spectra. For the first time, we report the existence of PhMNs firing at rates corresponding to high-frequency oscillations during eupneic motor output. The majority of PhMNs fired only during inspiration, but a small subpopulation possessed tonic activity throughout all phases of respiration. Significant time-varying PhMN-PhN coherence was observed for all PhMN classes. High-frequency, early-recruited units had significantly more consistent onset times than low-frequency, early/middle-recruited and medium-frequency, middle/late-recruited PhMNs. High- and medium-frequency PhMNs had significantly more consistent offset times than low-frequency units. This suggests that startup and termination of PhMNs with higher firing rates are more precisely controlled, which may contribute to the greater PhMN-PhN coherence at the beginning and end of inspiration. Our findings provide evidence that near-synchronous discharge of PhMNs firing at high rates may underlie fast oscillations in PhN discharge.

scholarly journals Training to Detect Phishing Emails: Effects of the Frequency of Experienced Phishing Emails

2019 ◽  
Vol 63 (1) ◽  
pp. 453-457
Author(s):  
Kuldeep Singh ◽  
Palvi Aggarwal ◽  
Prashanth Rajivan ◽  
Cleotilde Gonzalez
Keyword(s):  
False Alarm ◽  
False Alarm Rate ◽  
High Frequency ◽  
Low Frequency ◽  
Response Criterion ◽  
Training Phase ◽  
Medium Frequency ◽  
Hit Rate ◽  
Hit Rates ◽  
Training Protocols

We studied people’s success on the detection of phishing emails after they were trained under one of three phishing frequency conditions, where the proportion of the phishing emails during training varied as: low frequency (25% phishing emails), medium frequency (50% phishing emails) and high frequency (75% phishing emails). Individual base susceptibility to phishing emails was measured in a pre-training phase in which 20% of the emails were phishing; this performance was then compared to a post-training phase in which participants aimed at detecting new rare phishing emails (20% were phishing emails). The Hit rates, False Alarm rates, sensitivities and response criterion were analyzed. Results revealed that participants receiving higher frequency of phishing emails had a higher hit rate but also higher false alarm rate at detecting phishing emails at post-training compared to participants encountering lower frequency levels during training. These results have implications for designing new training protocols for improving detection of phishing emails.

scholarly journals Contingency Learning Tracks With Stimulus-Response Proportion

2016 ◽  
Vol 63 (2) ◽  
pp. 79-88 ◽  
Author(s):  
James R. Schmidt ◽  
Jan De Houwer
Keyword(s):  
High Frequency ◽  
Color Word ◽  
Low Frequency ◽  
Contingency Learning ◽  
Response Proportion ◽  
Medium Frequency ◽  
Frequency Condition ◽  
Stimulus Response ◽  
Human Contingency Learning ◽  
Print Color

Abstract. We investigate the processes involved in human contingency learning using the color-word contingency learning paradigm. In this task, participants respond to the print color of neutral words. Each word is frequently presented in one color. Results show that participants respond faster and more accurately to words presented in their expected color. In Experiment 1, we observed better performance for high- relative to medium-frequency word-color pairs, and for medium- relative to low-frequency pairs. Within the medium-frequency condition, it did not matter whether the word was predictive of a currently-unpresented color, or the color was predictive of a currently-unpresented word. We conclude that a given word facilitates each potential response proportional to how often they co-occurred. In contrast, there was no evidence for costs associated with violations of high-frequency expectancies. Experiment 2 further introduced a novel word baseline condition, which also provided no evidence for competition between retrieved responses.

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