Filter Results
21888 results
A phase-locking model for entrainment of peripheral oscillators to the cyclin–CDK oscillator. (a) Molecular mechanism of the Cdc14 release oscillator. The mitotic phosphatase Cdc14 is activated upon release from sequestration in the nucleolus. This release is controlled by a negative feedback loop in which Cdc14 release, promoted by the polo kinase Cdc5, activates APC-Cdh1, which then promotes Cdc5 degradation, allowing Cdc14 resequestration. This negative-feedback oscillator is entrained to the cyclin–CDK cycle at multiple points: by cyclin–CDK promotion of CDC5 transcription and Cdc5 kinase activation, and by cyclin–CDK inhibition of Cdh1 activity. (b) Schematic of multiple peripheral oscillators coupled to the CDK oscillator in budding yeast. As described above, coupling entrains such peripheral oscillators to cell cycle progression; peripheral oscillators also feed back on the cyclin–CDK oscillator itself. For example, major genes in the periodic transcription program include most cyclins, CDC20, and CDC5; Cdc14 directly promotes establishment of the low-cyclin–CDK positive feedback loop by activating Cdh1 and Sic1 as well as more indirectly antagonizing cyclin–CDK activity by dephosphorylating cyclin–CDK targets; the centrosome and budding cycles could communicate with the cyclin–CDK cycle via the spindle integrity and morphogenesis checkpoints. (c) Oscillator coupling ensures once-per-cell-cycle occurrence of events. Three hypothetical oscillators are shown: a master cycle in black, a faster peripheral cycle in blue, and a slower peripheral cycle in red. In the absence of phase-locking (top), the oscillators trigger events (colored circles) without a coherent phase relationship. In the presence of oscillator coupling (bottom), the peripheral oscillators are slowed or accelerated within their critical periods to produce a locked phase relationship, with events occurring once and only once within each master cycle. ... Positive and negative feedback loops in the cyclin–CDK oscillator. (a) Inset: a negative feedback loop which can give rise to oscillations. Such an oscillator is thought to form the core of eukaryotic cell cycles, with cyclin–Cyclin Dependent Kinase (cyclin–CDK) acting as activator, Anaphase Promoting Complex-Cdc20 (APC-Cdc20) acting as repressor, and non-linearity in APC-Cdc20 activation preventing the system from settling into a steady state. Below is shown the cyclin–CDK machinery in eukaryotic cell cycles. CDKs, present throughout the cell cycle, require the binding of a cyclin subunit for activity. These cyclin partners can also determine the localization of the complex and its specificity for targets. At the beginning of the cell cycle, cyclin–CDK activity is low, and ramps up over most of the cycle. Early cyclins trigger production of later cyclins and these later cyclins then turn off the earlier cyclins, so that control is passed from one set of cyclin–CDKs to the next. The last set of cyclins to be activated, the G2/M-phase cyclins, initiate mitosis, and also initiate their own destruction by activating the APC-Cdc20 negative feedback loop. APC-Cdc20 targets the G2/M-phase cyclins for destruction, resetting the cell to a low-CDK activity state, ready for the next cycle. (b) Positive feedback is added to the oscillator in multiple ways. Left: a highly conserved but non-essential mechanism consists of ‘handoff’ of cyclin proteolysis from APC-Cdc20 to APC-Cdh1. Cdh1 is a relative of Cdc20 which activates the APC late in mitosis and into the ensuing G1. Cdh1 is inhibited by cyclin–CDK activity, resulting in mutual inhibition (which is logically equivalent to positive feedback). Middle: antagonism between cyclin–CDK and stoichiometric CDK inhibitors (CKIs) results in positive feedback. These loops stabilize high- and low-CDK activity states. Right: a double positive feedback loop comprising CDK-mediated inhibition of the Wee1 kinase (which inhibits CDK) and activation of the Cdc25 phosphatase (which activates CDK by removing the phosphorylation added by Wee1) is proposed to stabilize intermediate CDK activity found in mid-cycle, and an alternative stable state of high mitotic CDK activity.
Data Types:
  • Image
Spatial frequencies distributions... Ragged oscillation death... The phase synchronization domains (areas enclosed by the red lines) and the OD regions (black areas) in the parameter space of ε-δω for a ring of coupled Rossler systems with different frequency distributions: (a) G={1,2,3,4,5,6,7,8}, (b) G={1,4,3,6,2,8,5,7}, and (c) G={1,2,3,6,8,4,7,5}. N=8. The ragged OD sates are clear in (b) and (c) within a certain interval of δω indicated by two vertical dashed lines. In all three insets, the values of ωj are plotted for given ω0=0 and δω=N. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) ... The bifurcation diagram and the largest Lyapunov exponent λ of the coupled Rossler oscillators versus the coupling strength ε with the same spatial arrangement of natural frequencies as in Fig. 1(a)–(c), respectively for δω=0.58. The bifurcation diagram is realized by the soft of XPPAUT [33] where the black dots are fixed points and the red dots are the maximum and minimum values of x1 for the stable periodic solution while the blue dots means the max/min values of x1 for the unstable periodical states. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) ... The critical curves of OD domain from analysis in N coupled Landau–Stuart oscillators for different N’s: (a) N=2, (b) N=3, and (c)–(e) N=4 for G={1,2,3,4},G={1,2,4,3}, and G={1,3,2,4}, respectively. The ragged OD domain is clear in (d). The numerical results with points within the domains perfectly verify the analytical results. ... The OD regions in the parameter space of ε-δω for a ring of coupled Rossler systems with different frequency distributions: (a) G={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30}, (b) G={26,16,25,18,5,14,10,4,6,7,21,12,23,8,1,15,9,29,28,11,2,20,27,30,3,13,17,22,24,19}, and (c) G={19,22,18,13,10,28,7,15,17,8,30,12,26,11,20,9,27,21,25,6,29,1,23,5,3,24,16,14,4,2}. N=30. In all three insets, the values of ωj are plotted for given ω0=0 and δω=N. ... Coupled nonidentical oscillators
Data Types:
  • Image
  • Tabular Data
Resonance response of the SET current to applied microwave frequencies, (a) over a large frequency range due to coupling with all device elements. (b) A resonance of interest believed to be associated with the IDQD. Central resonance peak is periodically split or suppressed with varying gate potential Vg2. The inset figure shows the response at Vg2=−9.5V (dashed line) and at Vg2=−8V plotted without offset for comparison. The feature repeats periodically as gate potential is increased further. ... Qubit... Differentiated SET current measured at 4.2K and zero source–drain bias as Vg1 is swept and Vg2 is incremented. Inset shows the main features: one main Coulomb oscillation indicated by the dashed line and subsidiary oscillations shown by the dotted lines.
Data Types:
  • Image
Nonlinear oscillator... He’s frequency formulation
Data Types:
  • Image
  • Tabular Data
Qubit... (Color online.) Contour plots of the normalized decay rate γ(τ)/γ0 of the qubit only in the cavity bath, versus the time interval τ between successive measurements, and the central frequency ωcav of the cavity mode. (a) The width of the cavity frequency is λ=10−4Δ, and accordingly the cavity quality factor Q=104. (b) The width of the cavity frequency λ=5×10−3Δ, corresponding to the cavity quality factor Q=2×103. The region 1⩽γ(τ)/γ0⩽1.05 is shown as light magenta. The QZE region corresponds to γ(τ)/γ01. Evidently, a transition from the QZE to the AZE is observed by varying the central frequency of the cavity mode at finite τ (τ>0.6Δ−1 when Q=104, and τ>2.6Δ−1 when Q=2×103). ... (Color online.) Time dependence of the probability for the qubit at its excited state. In the resonant case, the parameters are ωcav=Δ=100g and τ=0.1g−1. In the detuning case, the cavity mode frequency is varied to ωcav=80g. Note that the successive measurements slow down the decay rate of excited state in the resonant case, which is the QZE. While in the detuning case, the measurements speed up the qubit decay rate, which is the AZE. ... The normalized effective decay rate γ(τ)/γ0 of the qubit for two quality factors Q when τ=5Δ−1, in the presence of both the cavity bath and the low-frequency qubitʼs intrinsic bath. ... (Color online.) (a) Sketch of a qubit with the spontaneous dissipation rate γ coupled to a cavity with the loss rate κ via a coupling strength g. (b) and (c) schematically show the bath density spectrum of the qubit environment: (b) the Ohmic qubitʼs intrinsic bath (green dashed) and the Lorentzian cavity bath (red solid), (c) the low-frequency qubitʼs intrinsic bath (green dashed) and the Lorentzian cavity bath (red solid). ... (Color online.) (a) Superconducting circuit model of a frequency-tunable transmission line resonator, which is archived by changing the boundary condition, coupled with a qubit. (b) Superconducting circuit model (1) of the effective tunable inductors, which are consisted of a series array of SQUIDs (2).
Data Types:
  • Image
  • Tabular Data
Comparison of the oscillation in Fig. 17 and the basic frequency component L in Fig. 23. The replacement of the feedback channel loops by open areas for vortical flow made the feedback paths slightly shorter (and therefore the frequency higher).... Measured oscillation frequency with different feedback tube lengths of the oscillator shown in Fig. 7, plotted as a function of the supplied flow rate. Surprisingly, the frequency is neither proportional to the flow rate (as is usual in the constant Strouhal-number oscillators, e.g., Tesař et al., 2006) – nor constant (as in the oscillators with resonator channel (Tesař et al., 2013)). ... Fluidic oscillator... Results of measured dependence of oscillation frequency on the supplied flow rate in the layout shown in Figs. 20 and 12. Apart from basic frequency L, the output spectrum exhibited a much higher frequency component H. ... Frequency of generated oscillation plotted as a function of the air flow rate. Similarly as in Fig. 9 this dependence does not the fit the usual (constant Strouhal number) proportionality between frequency and flow rate. ... Basic data on the geometry of the oscillator used in the high-frequency experiments. ... Dependence of bubble natural oscillation frequency on the size – based on the measurements in Tesař (2013b). The line is fitted for constant value of oscillation Weber number We0.
Data Types:
  • Image
(a) The SNR vs noise intensity D for fs=30,15, and 100 Hz, respectively. (b) The mean synaptic input Isyn(t) vs time for fs=30 Hz and D=0.15 and 6, respectively. (c) The SNR for various frequencies for the cases of D=0.5 and 5, respectively, in the case of I0i=0.8 and I1=0.11, and Jij∈[−4,20]. (d) The SNR vs signal frequency for D=0.5 and 5, respectively, for the case of I0i∈[0,1] and I1=0.072. ... Intrinsic oscillations... The 40 Hz oscillation... The frequency sensitivity... The frequency fi and the corresponding height H of the main peak in PSD of Isyn(t) vs (a) A for the case of I0i∈[0,3.5]; (b) M in the case of Jij∈[−5,10]. ... I0i∈[0,2] and Jij∈[−1,10]. (a) The spatiotemporal firing pattern is plotted by recording the firing time tni defined by Xi(tni)>0 and Xi(tni−)frequency fi and the corresponding height H of the main peak in PSD of Isyn(t) for different coupling strength.
Data Types:
  • Image
Frequency spectrograms distribution along the axial direction (R/D=2). ... Frequency spectrograms of condensation oscillation [21]. ... Frequency spectrograms under radial position of R/D=3.0 and R/D=4.0. ... Half affected width of pressure oscillation. ... Pressure oscillation... Oscillation power axial distribution for low frequency region.
Data Types:
  • Image
  • Tabular Data
Trajectories on the phase torus. (a) resonant two-frequency regime with winding number w=1:2, (b) three-frequency regime. ... (Color online). Chart of the Lyapunov’s exponents for the system of three coupled phase oscillators (5) for Δ2=1. The color palette is given and decrypted under the picture. The numbers indicate the tongues of the main resonant two-frequency regimes. These regimes are explained in the description of Fig. 5. ... Rotation numbers ν1–2 and ν2–3 versus the frequency detuning Δ1 for the system (11). Values of the parameters are λ1=1.3,λ2=1.9,λ3=1.8,Δ2=1.5 and μ=0.32. ... Subdivision of the chain of four oscillators by clusters for the three types of the phase locked pair of oscillators. Parameters are chosen in such a way that the system of oscillators is near the point of the saddle–node bifurcation. ... Schematic representation of a system of three coupled self-oscillators. ... Phase oscillators
Data Types:
  • Image
Dependence of the phase shift α on the two parameters ng and Φe. The qubit is irradiated by microwaves with a frequency of 8.0GHz. The periodic circular structure is due to the variation of the total interferometer-tank impedance caused by transitions from the lower to the upper energy band. The “crater ridges” (solid-line ellipse) correspond to all combinations of the parameters ng and Φe that give the same energy gap (8.0GHz) between the respective states [14]. ... Tank phase shift α dependence on gate parameter ng for different magnetic flux applied to the qubit loop . The data correspond to the flux Φ/Φ0=0.5, 0.53, 0.54, 0.56, 0.57. 0.61, 0.62, 0.65 (from bottom to top). For clarity, the upper curves are shifted. ... Superconducting qubits... Integrated design: Al qubit fabricated in the middle of the Nb coil (left-hand side), and single-Cooper-pair transistor (right-hand side). ... Left-hand side: tank phase shift α dependence on gate parameter ng without microwave power (lowest curve) and with microwave power at different excitation frequencies. The data correspond to the frequency of the microwave ΩMW/2π=8.9, 7.5, 6.0GHz (from top to bottom) [14]. Here the applied external magnetic flux was fixed Φdc=Φ0/2. For clarity, the upper curves are shifted. Right-hand side: energy gap Δ between the ground and upper states of the qubit determined from the experimental data for the case δ=π (Φdc=Φ0/2) [14]. The dots represent the experimental data, the solid line corresponds to the fit (cf. text). ... Calculated dependence of the tank voltage phase shift α on the phase difference δ. The curves correspond to the fixed frequency Ω/2π=7.05GHz with the different amplitude of the excitation (from bottom to top n˜g is: 0.1, 0.2, 0.4) [11]. For clarity, the upper curves are shifted.
Data Types:
  • Image
6