72 results for qubit oscillator frequency
Contributors: Rego Costa, Artur, Débarre, Florence, Chevin, Luis-Miguel
frequency-dependent selection caused by competitive interactions mediated...frequency of chaos at each simulation time point for different values ...oscillating optimum for d = 70....oscillations of an optimal phenotype interacts with the internal dynamics...oscillations. In contrast, weak forcing can increase the probability of...oscillating optimum for d = 40. ... Among the factors that may reduce the predictability of evolution, chaos, characterized by a strong dependence on initial conditions, has received much less attention than randomness due to genetic drift or environmental stochasticity. It was recently shown that chaos in phenotypic evolution arises commonly under frequency-dependent selection caused by competitive interactions mediated by many traits. This result has been used to argue that chaos should often make evolutionary dynamics unpredictable. However, populations also evolve largely in response to external changing environments, and such environmental forcing is likely to influence the outcome of evolution in systems prone to chaos. We investigate how a changing environment causing oscillations of an optimal phenotype interacts with the internal dynamics of an eco-evolutionary system that would be chaotic in a constant environment. We show that strong environmental forcing can improve the predictability of evolution, by reducing the probability of chaos arising, and by dampening the magnitude of chaotic oscillations. In contrast, weak forcing can increase the probability of chaos, but it also causes evolutionary trajectories to track the environment more closely. Overall, our results indicate that, although chaos may occur in evolution, it does not necessarily undermine its predictability.
Contributors: Farzad Rafieian, François Girardin, Zhaoheng Liu, Marc Thomas, Bruce Hazel
frequency clearly indicates the impacting nature of the process and captures...oscillations. (For interpretation of the references to color in this figure...high-frequency repeating impacts in robotic grinding (detailed views)....frequency in single-pass grinding (overview). (For interpretation of the...frequency...frequency in Test (3) at 4500rpm. (For interpretation of the references...high-frequency impacts that mainly last for only a small fraction of the ... In a robotic machining process, a light-weight cutter or grinder is usually held by an articulated robot arm. Material removal is achieved by the rotating cutting tool while the robot end effector ensures that the tool follows a programmed trajectory in order to work on complex curved surfaces or to access hard-to-reach areas. One typical application of such process is maintenance and repair work on hydropower equipment. This paper presents an experimental study of the dynamic characteristics of material removal in robotic grinding, which is unlike conventional grinding due to the lower structural stiffness of the tool-holder robot. The objective of the study is to explore the cyclic nature of this mechanical operation to provide the basis for future development of better process control strategies. Grinding tasks that minimize the number of iterations to converge to the target surface can be better planned based on a good understanding and modeling of the cyclic material removal mechanism. A single degree of freedom dynamic analysis of the process suggests that material removal is performed through high-frequency impacts that mainly last for only a small fraction of the grinding disk rotation period. To detect these discrete cutting events in practice, a grinder is equipped with a rotary encoder. The encoder's signal is acquired through the angular sampling technique. A running cyclic synchronous average is applied to the speed signal to remove its non-cyclic events. The measured instantaneous rotational frequency clearly indicates the impacting nature of the process and captures the transient response excited by these cyclic impacts. The technique also locates the angular positions of cutting impacts in revolution cycles. It is thus possible to draw conclusions about the cyclic nature of dynamic changes in impact-cutting behavior when grinding with a flexible robot. The dynamics of the impacting regime and transient responses to impact-cutting excitations captured synchronously using the angular sampling technique provide feedback that can be used to regulate the material removal process. The experimental results also make it possible to correlate the energy required to remove a chip of metal through impacting with the measured drop in angular speed during grinding.
Contributors: Schanz, Ansgar, Hocke, Klemens, Kämpfer, Niklaus
oscillations is challenging. However, dynamical responses to short-term...oscillations. Two simulations were conducted with short-term solar forcing...oscillation comes along with other periods of the extra-long period wave ... The Whole Atmosphere Community Climate Model was used to investigate the influences of solar fluctuations on zonal wind oscillations. Two simulations were conducted with short-term solar forcing (<35 days) on and off. We found that a 27-day wave is an inherent feature of the atmosphere when the short-term solar forcing is inactive. This internal 27-day oscillation comes along with other periods of the extra-long period wave band (20–40 days) and cannot be linked to the Sun’s rotation period. When the short-term solar variability is part of the forcing, including the solar 27-day periodicity, it affects a wide range of the spectrum of zonal wind. At mid-latitudes, a 10-day wave emerges by the short-term solar forcing, which suggests that indirect and nonlinear interactions are involved. Solar short-term variability seems to generate atmospheric perturbations that interact with modes of the internal wave spectrum or the background mean flow. A robust and clear solar interpretation of these wind oscillations is challenging. However, dynamical responses to short-term solar variability exist and need further investigation.
Contributors: Cliff Orori Mosiori
frequencies just like those under seismic wave interactions and this work...oscillations are expected to behave in cylinder carrying a suspended mass...oscillator in a cylindrical acoustic medium that allow such waves to be...Oscillations ... Free vibrating motion can take place in an acoustic media. This motion can be steady hence have constant periodic variations or unsteady and thus experience light damping or heavy damping. We give a modeled analysis of unsteady periodic motion of an oscillator in a cylindrical acoustic medium that allow such waves to be transmitted through them. This has been approached by calculating variation within the proposed boundary functions and boundary potentials. Limitations for these calculations have been done depending on the time, and how free oscillations are expected to behave in cylinder carrying a suspended mass. This work investigated motion by constructions that interact with their environment with the acoustic media. Since the dynamics considered here were very complex, modeling the system with one grade of free motion and applying different types of constructions whether ground, underground, cylindrical, spherical constructions and containers was considered. This work borrowed heavily on the modeling of seismic and blast waves as modeled with rigid inclusions containing elastically fastened mass interacting continuous solid medium. This study joined motion of any continuous medium with other discrete systems. The results displayed measurement systems for wave processes having interference at their eigen- frequencies just like those under seismic wave interactions and this work considered the result as similar to those in discrete systems.
Contributors: Smith, Robert W., van Sluijs, Bob, Fleck, Christian
oscillations. In this work we present a generalised in silico evolutionary...oscillators, and by performing multi-objective optimisation to find a ...oscillators and feed-forward loops that are optimal at balancing different...oscillators for experimental construction.Conclusions: In this work we ... Background: Evolution has led to the development of biological networks that are shaped by environmental signals. Elucidating, understanding and then reconstructing important network motifs is one of the principal aims of Systems & Synthetic Biology. Consequently, previous research has focused on finding optimal network structures and reaction rates that respond to pulses or produce stable oscillations. In this work we present a generalised in silico evolutionary algorithm that simultaneously finds network structures and reaction rates (genotypes) that can satisfy multiple defined objectives (phenotypes).Results: The key step to our approach is to translate a schema/binary-based description of biological networks into systems of ordinary differential equations (ODEs). The ODEs can then be solved numerically to provide dynamic information about an evolved networks functionality. Initially we benchmark algorithm performance by finding optimal networks that can recapitulate concentration time-series data and perform parameter optimisation on oscillatory dynamics of the Repressilator. We go on to show the utility of our algorithm by finding new designs for robust synthetic oscillators, and by performing multi-objective optimisation to find a set of oscillators and feed-forward loops that are optimal at balancing different system properties. In sum, our results not only confirm and build on previous observations but we also provide new designs of synthetic oscillators for experimental construction.Conclusions: In this work we have presented and tested an evolutionary algorithm that can design a biological network to produce desired output. Given that previous designs of synthetic networks have been limited to subregions of network- and parameter-space, the use of our evolutionary optimisation algorithm will enable Synthetic Biologists to construct new systems with the potential to display a wider range of complex responses.
Coordinated expression and genetic polymorphisms in Grainyhead-like genes in human non-melanoma skin cancers
Contributors: Kikulska, Agnieszka, Rausch, Tobias, Krzywinska, Ewa, Pawlak, Magdalena, Wilczynski, Bartek, Benes, Vladimir, Rutkowski, Piotr, Wilanowski, Tomasz
frequencies in the examined group of NMSC patients.Conclusions: Non-melanoma...frequencies in NMSC patients, and they may in particular impair the expression ... Background: The Grainyhead-like (GRHL) transcription factors have been linked to many different types of cancer. However, no previous study has attempted to investigate potential correlations in expression of different GRHL genes in this context. Furthermore, there is very little information concerning damaging mutations and/or single nucleotide polymorphisms in GRHL genes that may be linked to cancer.Methods: DNA and RNA were extracted from human non-melanoma skin cancers (NMSC) and adjacent normal tissues (n = 33 pairs of samples). The expression of GRHL genes was measured by quantitative real time PCR. Regulation of GRHL expression by miRNA was studied using cell transfection methods and dual-luciferase reporter system. Targeted deep sequencing of GRHL genes in tumor samples and control tissues were employed to search for mutations and single nucleotide polymorphisms. Single marker rs141193530 was genotyped with pyrosequencing in additional NMSC replication cohort (n = 176). Appropriate statistical and bioinformatic methods were used to analyze and interpret results.Results: We discovered that the expression of two genes – GRHL1 and GRHL3 – is reduced in a coordinated manner in tumor samples, in comparison to the control healthy skin samples obtained from the same individuals. It is possible that both GRHL1 and GRHL3 are regulated, at least to some extent, by different strands of the same oncogenic microRNA – miR-21, what would at least partially explain observed correlation. No de novo mutations in the GRHL genes were detected in the examined tumor samples. However, some single nucleotide polymorphisms in the GRHL genes occur at significantly altered frequencies in the examined group of NMSC patients.Conclusions: Non-melanoma skin cancer growth is accompanied by coordinated reduced expression of epidermal differentiation genes: GRHL1 and GRHL3, which may be regulated by miR-21–3p and -5p, respectively. Some potentially damaging single nucleotide polymorphisms in GRHL genes occur with altered frequencies in NMSC patients, and they may in particular impair the expression of GRHL3 gene or functioning of encoded protein. The presence of these polymorphisms may indicate an increased risk of NMSC development in affected people.
Contributors: Edoardo Paluan
frequency 800Hz.txt...frequency of the diapason....oscillate at various frequencies. The distance travelled by M2 due to ... The aim of the project is to create an optical interferometer which can detect the acoustic analogue of a supernova explosion. The fingerprint of an acoustic wave propagating from a diapason will be measured. A Michelson Morley interferometer1 will be used, whereby analysis of the interference pattern will allow for the calculation of the frequency of the diapason.
Data from: Neural mechanisms of rhythm-based temporal prediction: delta phase-locking reflects temporal predictability but not rhythmic entrainment
Contributors: Breska, Assaf, Deouell, Leon Y.
low-frequency neural activity for rhythmic compared to random streams....low-frequency neural oscillations to the rhythm, as indicated by increased...low-frequency oscillations ... Predicting the timing of upcoming events enables efficient resource allocation and action preparation. Rhythmic streams, such as music, speech, and biological motion, constitute a pervasive source for temporal predictions. Widely accepted entrainment theories postulate that rhythm-based predictions are mediated by synchronizing low-frequency neural oscillations to the rhythm, as indicated by increased phase concentration (PC) of low-frequency neural activity for rhythmic compared to random streams. However, we show here that PC enhancement in scalp recordings is not specific to rhythms but is observed to the same extent in less periodic streams if they enable memory-based prediction. This is inconsistent with the predictions of a computational entrainment model of stronger PC for rhythmic streams. Anticipatory change in alpha activity and facilitation of electroencephalogram (EEG) manifestations of response selection are also comparable between rhythm- and memory-based predictions. However, rhythmic sequences uniquely result in obligatory depression of preparation-related premotor brain activity when an on-beat event is omitted, even when it is strategically beneficial to maintain preparation, leading to larger behavioral costs for violation of prediction. Thus, while our findings undermine the validity of PC as a sign of rhythmic entrainment, they constitute the first electrophysiological dissociation, to our knowledge, between mechanisms of rhythmic predictions and of memory-based predictions: the former obligatorily lead to resonance-like preparation patterns (that are in line with entrainment), while the latter allow flexible resource allocation in time regardless of periodicity in the input. Taken together, they delineate the neural mechanisms of three distinct modes of preparation: continuous vigilance, interval-timing-based prediction and rhythm-based prediction.
Contributors: Choudhary, Mahipal, van Mastrigt, Ron, van Asselt, Els
... Tibial nerve stimulation (TNS) is a form of peripheral neuromodulation which has been found effective in treating overactive bladder symptoms, with lesser side effects than first line pharmacotherapy. Despite its widespread clinical use, the underlying mechanism of action is not fully understood. Our aim was to study its effect on the bladder neurophysiology and the trigger mechanism of voiding in the overactive detrusor, simulated by acetic acid (AA) instillation. In urethane anaesthetized male Wistar rats, the tibial nerve was stimulated for 30 min at 5 Hz, pulse width 200 µs and amplitude approximately three times the threshold to induce a slight toe movement. The pressure at which a voiding contraction was triggered (pthres) did not change significantly between the pre- and post-TNS measurements in AA induced detrusor overactivity. It was found that TNS significantly reversed the effects of AA irritation by increasing the bladder compliance and the bladder volume at pthres, as well as suppressed the threshold afferent nerve activity. The slope of the linear relationship between pressure and the afferent activity increased after AA instillation and decreased significantly after stimulation. In addition to its well-known central inhibitory mechanisms, this study has demonstrated that TNS improves bladder storage capacity by delaying the onset of voiding, via an inhibitory effect on the bladder afferent signaling at the peripheral level.
Contributors: Sigalas, Charalambos, Konsolaki, Eleni, Skaliora, Irini
... Background: Several molecular and cellular processes in the vertebrate brain exhibit differences between males and females, leading to sexual dimorphism in the formation of neural circuits and brain organization. While studies on large-scale brain networks provide ample evidence for both structural and functional sex differences, smaller-scale local networks have remained largely unexplored. In the current study, we investigate sexual dimorphism in cortical dynamics by means of spontaneous Up/Down states, a type of network activity that is exhibited during slow-wave sleep, quiet wakefulness, and anesthesia and is thought to represent the default activity of the cortex.Methods: Up state activity was monitored by local field potential recordings in coronal brain slices of male and female mice across three ages with distinct secretion profiles of sex hormones: (i) pre-puberty (17–21 days old), (ii) 3–9 adult (months old), and (iii) old (19–24 months old).Results: Female mice of all ages exhibited longer and more frequent Up states compared to aged-matched male mice. Power spectrum analysis revealed sex differences in the relative power of Up state events, with female mice showing reduced power in the delta range (1–4 Hz) and increased power in the theta range (4–8 Hz) compared to male mice. No sex differences were found in the characteristics of Up state peak voltage and latency.Conclusions: The present study revealed for the first time sex differences in intracortical network activity, using an ex vivo paradigm of spontaneously occurring Up/Down states. We report significant sex differences in Up state properties that are already present in pre-puberty animals and are maintained through adulthood and old age.