Статті в журналах з теми "Coherent drive"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Coherent drive.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Coherent drive".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Miao, Kevin C., Alexandre Bourassa, Christopher P. Anderson, Samuel J. Whiteley, Alexander L. Crook, Sam L. Bayliss, Gary Wolfowicz, et al. "Electrically driven optical interferometry with spins in silicon carbide." Science Advances 5, no. 11 (November 2019): eaay0527. http://dx.doi.org/10.1126/sciadv.aay0527.
Анотація:
Interfacing solid-state defect electron spins to other quantum systems is an ongoing challenge. The ground-state spin’s weak coupling to its environment not only bestows excellent coherence properties but also limits desired drive fields. The excited-state orbitals of these electrons, however, can exhibit stronger coupling to phononic and electric fields. Here, we demonstrate electrically driven coherent quantum interference in the optical transition of single, basally oriented divacancies in commercially available 4H silicon carbide. By applying microwave frequency electric fields, we coherently drive the divacancy’s excited-state orbitals and induce Landau-Zener-Stückelberg interference fringes in the resonant optical absorption spectrum. In addition, we find remarkably coherent optical and spin subsystems enabled by the basal divacancy’s symmetry. These properties establish divacancies as strong candidates for quantum communication and hybrid system applications, where simultaneous control over optical and spin degrees of freedom is paramount.
2
Kobayashi, Yuki, and Stephen R. Leone. "Characterizing coherences in chemical dynamics with attosecond time-resolved x-ray absorption spectroscopy." Journal of Chemical Physics 157, no. 18 (November 14, 2022): 180901. http://dx.doi.org/10.1063/5.0119942.
Анотація:
Coherence can drive wave-like motion of electrons and nuclei in photoexcited systems, which can yield fast and efficient ways to exert materials’ functionalities beyond the thermodynamic limit. The search for coherent phenomena has been a central topic in chemical physics although their direct characterization is often elusive. Here, we highlight recent advances in time-resolved x-ray absorption spectroscopy (tr-XAS) to investigate coherent phenomena, especially those that utilize the eminent light source of isolated attosecond pulses. The unparalleled time and state sensitivities of tr-XAS in tandem with the unique element specificity render the method suitable to study valence electronic dynamics in a wide variety of materials. The latest studies have demonstrated the capabilities of tr-XAS to characterize coupled electronic–structural coherence in small molecules and coherent light–matter interactions of core-excited excitons in solids. We address current opportunities and challenges in the exploration of coherent phenomena, with potential applications for energy- and bio-related systems, potential crossings, strongly driven solids, and quantum materials. With the ongoing developments in both theory and light sources, tr-XAS holds great promise for revealing the role of coherences in chemical dynamics.
3
Melrose, Don. "Maser Emission in Astrophysical Plasmas: 2003 Robert Ellery Lecture." Publications of the Astronomical Society of Australia 22, no. 2 (2005): 144–52. http://dx.doi.org/10.1071/as04061.
Анотація:
AbstractThere are three distinct types of ‘coherent emission’ in astrophysical plasmas: plasma emission (e.g. in solar radio bursts), electron cyclotron maser emission (e.g. in Jupiter's radio bursts), and pulsar radio emission. The development and current status of our understanding of coherent emission is reviewed, concentrating on plasma emission and electron cyclotron maser emission for which there is direct information on the distributions of electrons that produce the radiation. A generic model for a coherent emission process involves a maser generating radiation in a natural mode of the ambient plasma, and operating near marginal stability. A specific coherent emission mechanism involves the form of free energy to drive the maser, a pump that provides the free energy, and the plasma instability that leads to wave growth. The nature of coherence and its measurement through higher order intensity correlations are discussed.
4
Dann, Roie, and Ronnie Kosloff. "Quantum thermo-dynamical construction for driven open quantum systems." Quantum 5 (November 25, 2021): 590. http://dx.doi.org/10.22331/q-2021-11-25-590.
Анотація:
Quantum dynamics of driven open systems should be compatible with both quantum mechanic and thermodynamic principles. By formulating the thermodynamic principles in terms of a set of postulates we obtain a thermodynamically consistent master equation. Following an axiomatic approach, we base the analysis on an autonomous description, incorporating the drive as a large transient control quantum system. In the appropriate physical limit, we derive the semi-classical description, where the control is incorporated as a time-dependent term in the system Hamiltonian. The transition to the semi-classical description reflects the conservation of global coherence and highlights the crucial role of coherence in the initial control state. We demonstrate the theory by analyzing a qubit controlled by a single bosonic mode in a coherent state.
5
Yang, Kai, William Paul, Soo-Hyon Phark, Philip Willke, Yujeong Bae, Taeyoung Choi, Taner Esat, Arzhang Ardavan, Andreas J. Heinrich, and Christopher P. Lutz. "Coherent spin manipulation of individual atoms on a surface." Science 366, no. 6464 (October 24, 2019): 509–12. http://dx.doi.org/10.1126/science.aay6779.
Анотація:
Achieving time-domain control of quantum states with atomic-scale spatial resolution in nanostructures is a long-term goal in quantum nanoscience and spintronics. Here, we demonstrate coherent spin rotations of individual atoms on a surface at the nanosecond time scale, using an all-electric scheme in a scanning tunneling microscope (STM). By modulating the atomically confined magnetic interaction between the STM tip and surface atoms, we drive quantum Rabi oscillations between spin-up and spin-down states in as little as ~20 nanoseconds. Ramsey fringes and spin echo signals allow us to understand and improve quantum coherence. We further demonstrate coherent operations on engineered atomic dimers. The coherent control of spins arranged with atomic precision provides a solid-state platform for quantum-state engineering and simulation of many-body systems.
6
Alam, Jahrul M. "Wavelet Transforms and Machine Learning Methods for the Study of Turbulence." Fluids 8, no. 8 (August 3, 2023): 224. http://dx.doi.org/10.3390/fluids8080224.
Анотація:
This article investigates the applications of wavelet transforms and machine learning methods in studying turbulent flows. The wavelet-based hierarchical eddy-capturing framework is built upon first principle physical models. Specifically, the coherent vortex simulation method is based on the Taylor hypothesis, which suggests that the energy cascade occurs through vortex stretching. In contrast, the adaptive wavelet collocation method relies on the Richardson hypothesis, where the self-amplification of the strain field and a hierarchical breakdown of large eddies drive the energy cascade. Wavelet transforms are computational learning architectures that propagate the input data across a sequence of linear operators to learn the underlying nonlinearity and coherent structure. Machine learning offers a wealth of data-driven algorithms that can heavily use statistical concepts to extract valuable insights into turbulent flows. Supervised machine learning needs “perfect” turbulent flow data to train data-driven turbulence models. The current advancement of artificial intelligence in turbulence modeling primarily focuses on accelerating turbulent flow simulations by learning the underlying coherence over a low-dimensional manifold. Physics-informed neural networks offer a fertile ground for augmenting first principle physics to automate specific learning tasks, e.g., via wavelet transforms. Besides machine learning, there is room for developing a common computational framework to provide a rich cross-fertilization between learning the data coherence and the first principles of multiscale physics.
7
Ampadu Boateng, Derrick, Gennady L. Gutsev, Puru Jena, and Katharine Moore Tibbetts. "Ultrafast coherent vibrational dynamics in dimethyl methylphosphonate radical cation." Physical Chemistry Chemical Physics 20, no. 7 (2018): 4636–40. http://dx.doi.org/10.1039/c7cp07261a.
8
Shumin Zou, Shumin Zou, Yiguang Wang Yiguang Wang, Yufeng Shao Yufeng Shao, Junwen Zhang Junwen Zhang, Jianjun Yu Jianjun Yu, and Nan Chi Nan Chi. "Generation of coherent optical multi-carriers using concatenated, dual-drive Mach-Zehnder and phase modulators." Chinese Optics Letters 10, no. 7 (2012): 070605–70609. http://dx.doi.org/10.3788/col201210.070605.
9
Fast, Alexander, and Eric Olaf Potma. "Coherent Raman scattering with plasmonic antennas." Nanophotonics 8, no. 6 (May 21, 2019): 991–1021. http://dx.doi.org/10.1515/nanoph-2019-0097.
Анотація:
AbstractCoherent Raman scattering (CRS) techniques are recognized for their ability to induce and detect vibrational coherences in molecular samples. The generation of coherent light fields in CRS produces much stronger signals than what is common in incoherent Raman spectroscopy, while also enabling direct views of evolving molecular vibrations. Despite the attractive attributes of CRS spectroscopy, the technique’s sensitivity is insufficient for performing measurements on single molecules, thus precluding the ability to coherently drive, manipulate and observe individual vibrational quantum oscillators with light. The single-molecule sensitivity that has been achieved in surface-enhanced Raman scattering (SERS) with the aid of plasmonic antennas suggests that a similar approach may be used to push CRS techniques to the single-molecule detection limit. Compared with SERS, however, experimental successes in surface-enhanced coherent Raman scattering (SE-CRS) are few, and a theoretical understanding of surface-enhancement in CRS is still incomplete. In this review, we discuss some of the principles and challenges in SE-CRS and summarize the latest advances in the quest of performing routine CRS experiments on single molecules.
10
Farahat, Omar M. "A DEVOTIONAL THEORY OF LAW: EPISTEMOLOGY AND MORAL PURPOSE IN EARLY ISLAMIC JURISPRUDENCE." Journal of Law and Religion 31, no. 1 (March 2016): 42–69. http://dx.doi.org/10.1017/jlr.2016.2.
Анотація:
AbstractThe question of the sources of legal normativity continues to haunt legal theorists to this day. While it is largely uncontroversial that modern legal systems claim to produce normative propositions, whether or not there are independent reasons to obey the law remains a contested issue. Those views, as varied as they may be, appear to largely agree that the law is a social phenomenon of definite ontological presence. In this article, I argue, through an analysis of the theories of three prominent ninth- to eleventh-century Muslim jurists, that early Muslim theories of lawmaking did not incorporate any ontologically coherent concept of law. Rather, lawmaking was understood as the case-by-case formulation of legal opinions by individual jurists who were presumed to be driven by the same moral drive, and therefore occupy the same moral order, as all subjects of law. In spite of this ad hoc epistemological view, Islamic jurisprudence conceived of legal pronouncements as fully normative. The normativity of those unstructured ad hoc individual pronouncements, I maintain, is the result of the centrality of moral purpose to early Muslim theories of law. It was the presumption of a common moral drive that gave the legal system structural coherence and allowed the advancement of those pronouncements as normative claims. Whereas recent historical and anthropological work shows that moral motivation was central to the manner in which sharīʿa operated as a system of social regulation, this article argues, along the same lines, that the pietistic drive was both conceptually and structurally indispensable for the normative coherence of early Islamic jurisprudence.
11
Hertler, Steven Charles. "The Evolutionary Logic of the Obsessive Trait Complex: Obsessive Compulsive Personality Disorder as a Complementary Behavioral Syndrome." Psychological Thought 8, no. 1 (April 30, 2015): 17–34. http://dx.doi.org/10.5964/psyct.v8i1.125.
Анотація:
Freud noted that the obsessive traits of orderliness, parsimony, and obstinacy incontestably belonged together. This observation has been unfailingly justified, but unsatisfactorily explained. Being a highly heritable pattern essentially unaffected by parental influence, it is counterfactual to continue to explain the obsessive trait constellation as a pathological signature of harsh, authoritarian parenting. Alternatively, the present paper, building upon a previously promulgated evolutionary etiological model, describes how obsessive traits work in unison to enable survival within harsh northerly climates. What appears to be a loosely federated inventory of pathology, after the application of evolutionary reasoning, becomes a coherent behavioral package, adaptive suite, or behavioral syndrome. All three of these terms, taken from behavioral biology, suggest that traits strategically covary, such that the adaptive value of each trait is enhanced by the presence of the others. In this vein, the union of anxious tension and conscientiousness drives the obsessive personality to labor incessantly. The fruits of obsessive labor are then conserved through parsimoniousness, hoarding, vigilance, and niggardliness. And so, obsessive personality is a coherent behavioral package in that the drive to work towards the acquisition of necessities is paired with the drive to conserve and defend them.
12
Saintillan, David, Michael J. Shelley, and Alexandra Zidovska. "Extensile motor activity drives coherent motions in a model of interphase chromatin." Proceedings of the National Academy of Sciences 115, no. 45 (October 22, 2018): 11442–47. http://dx.doi.org/10.1073/pnas.1807073115.
Анотація:
The 3D spatiotemporal organization of the human genome inside the cell nucleus remains a major open question in cellular biology. In the time between two cell divisions, chromatin—the functional form of DNA in cells—fills the nucleus in its uncondensed polymeric form. Recent in vivo imaging experiments reveal that the chromatin moves coherently, having displacements with long-ranged correlations on the scale of micrometers and lasting for seconds. To elucidate the mechanism(s) behind these motions, we develop a coarse-grained active polymer model where chromatin is represented as a confined flexible chain acted upon by molecular motors that drive fluid flows by exerting dipolar forces on the system. Numerical simulations of this model account for steric and hydrodynamic interactions as well as internal chain mechanics. These demonstrate that coherent motions emerge in systems involving extensile dipoles and are accompanied by large-scale chain reconfigurations and nematic ordering. Comparisons with experiments show good qualitative agreement and support the hypothesis that self-organizing long-ranged hydrodynamic couplings between chromatin-associated active motor proteins are responsible for the observed coherent dynamics.
13
Vashahri-Ghamsari, Saeid, and Bing He. "Gain Saturation Modified Quantum Noise Effect on Preparing a Continuous-Variable Entanglement." Photonics 9, no. 9 (August 30, 2022): 620. http://dx.doi.org/10.3390/photonics9090620.
Анотація:
We examine the gain saturation effect in non-Hermitian systems of coupled gain–loss waveguides and whispering-gallery-mode microresonators, through which a continuous-variable (CV) entanglement of light fields is generated. Here, we consider squeezed vacuum inputs for coupled waveguide setup and coherent drive for coupled microresonators, and study the influence from the saturation of the used optical gain. Unlike the ideal situation without gain saturation, it is possible to generate stabilized entanglement measured by logarithmic negativity under gain saturation. Both types of setups realize steady CV entanglement, provided that the gain saturation is sufficiently quick. Particularly, with the coupled microresonators which are pumped by coherent drive, the created CV entanglement is actually out of the gain noise with a squeezing characteristic, under the condition of fast saturation of the initial optical gain.
14
Thompson, Christopher K., Michael D. Johnson, Francesco Negro, Laura Miller Mcpherson, Dario Farina, and Charles J. Heckman. "Exogenous neuromodulation of spinal neurons induces beta-band coherence during self-sustained discharge of hind limb motor unit populations." Journal of Applied Physiology 127, no. 4 (October 1, 2019): 1034–41. http://dx.doi.org/10.1152/japplphysiol.00110.2019.
Анотація:
The spontaneous or self-sustained discharge of spinal motoneurons can be observed in both animals and humans. Although the origins of this self-sustained discharge are not fully known, it can be generated by activation of persistent inward currents intrinsic to the motoneuron. If self-sustained discharge is generated exclusively through this intrinsic mechanism, the discharge of individual motor units will be relatively independent of one another. Alternatively, if increased activation of premotor circuits underlies this prolonged discharge of spinal motoneurons, we would expect correlated activity among motoneurons. Our aim is to assess potential synaptic drive by quantifying coherence during self-sustained discharge of spinal motoneurons. Electromyographic activity was collected from 20 decerebrate animals using a 64-channel electrode grid placed on the isolated soleus muscle before and following intrathecal administration of methoxamine, a selective α1-noradrenergic agonist. Sustained muscle activity was recorded and decomposed into the discharge times of ~10–30 concurrently active individual motor units. Consistent with previous reports, the self-sustained discharge of motor units occurred at low mean discharge rates with low-interspike variability. Before methoxamine administration, significant low-frequency coherence (<2 Hz) was observed, while minimal coherence was observed within higher frequency bands. Following intrathecal administration of methoxamine, increases in motor unit discharge rates and strong coherence in both the low-frequency and 15- to 30-Hz beta bands were observed. These data demonstrate beta-band coherence among motor units can be observed through noncortical mechanisms and that neuromodulation of spinal/brainstem neurons greatly influences coherent discharge within spinal motor pools. NEW & NOTEWORTHY The correlated discharge of spinal motoneurons is often used to describe the input to the motor pool. We demonstrate spinal/brainstem neurons devoid of cortical input can generate correlated motor unit discharge in the 15- to 30-Hz beta band, which is amplified through neuromodulation. Activity in the beta band is often ascribed to cortical drive in humans; however, these data demonstrate the capability of the mammalian segmental motor system to generate and modulate this coherent state of motor unit discharge.
15
TUCCI, ROBERT R. "ENTROPY OF A TWO LEVEL ATOM IN CONTACT WITH A SQUEEZED RESERVOIR." International Journal of Modern Physics B 05, no. 09 (May 20, 1991): 1457–84. http://dx.doi.org/10.1142/s0217979291000699.
Анотація:
We study the entropy of a two level atom in contact with a non-minimum uncertainty squeezed reservoir and a coherent drive. Let δ<b> be the phase of the coherent drive, and ΩR/γ the Rabi frequency divided by the atomic decay rate. For large, near minimum uncertainty squeezing, we find that the atomic quantum state is approximately a pure state, or, equivalently, a minimum entropy state, if ΩR/γ and δ<b> satisfy (ΩR/γ)| cos δ<b>| = 1/2. (Previous workers have only noted the occurrence of a pure state at δ<b> = 0 or 180°.) We find that the atom saturates separately in each quadrature of the coherent drive. We also find that the thermodynamic order of the atom (given by the magnitude of the Bloch vector or by the negative of the atomic entropy) may increase as the background fluctuations or disorder increase. This behavior does not occur with non-squeezed reservoirs; it may be interpreted as a negative temperature effect, if atomic temperatures are defined in terms of the derivatives of the atomic entropy with respect to the variances of the two reservoir quadratures. We give an extensive collection of plots of the atomic entropy and temperatures. We find that a harmonic oscillator always cools down to lower temperatures than a 2 level atom if both bodies are in contact with the same squeezed reservoir.
16
Romadanov, I., Y. Raitses, and A. Smolyakov. "Control of Coherent Structures via External Drive of the Breathing Mode." Plasma Physics Reports 45, no. 2 (February 2019): 134–46. http://dx.doi.org/10.1134/s1063780x19020156.
17
Seal, Dipayan, Pinaki Chaudhury та Subhasree Ghosh. "Coherent destruction of tunnelling in a symmetrical double well driven by a series of time dependent δ functions". Journal of Physics A: Mathematical and Theoretical 55, № 42 (21 жовтня 2022): 425307. http://dx.doi.org/10.1088/1751-8121/ac980c.
Анотація:
Abstract It is analytically and numerically shown that the coherent tunnelling between the individual wells of a symmetrical double well potential can be totally suppressed when it is driven by a periodic series of δ function in time, depending on the time period and strength of the δ function. We have applied time dependent perturbation theory to have an understanding over the process. In absence of any kind of perturbation, the average position of the particle makes a sinusoidal oscillation between two wells. With the application of a periodic δ function, the amplitude and the frequency of the oscillation both get modified. In this article we have explored how the frequency and strength of the applied perturbation controls the quantum dynamics of tunnelling and finally, how these parameters drive the system towards a complete stand still situation, which is described as coherent destruction of tunnelling.
18
Kundt, Wolfgang. "How well are Neutron Stars understood?" International Astronomical Union Colloquium 177 (2000): 597–98. http://dx.doi.org/10.1017/s025292110006070x.
Анотація:
AbstractAlternative ways are discussed in which pulsars may (1) drive their winds, (2) avoid net electric currents, (3) emit coherent radio pulses, (4) acquire high spin rates, and (5) deal with moderate surface magnetic fields: 1011<B/G≲ 1014.
19
STERN, TOM. "Against Nietzsche's ‘Theory’ of the Drives." Journal of the American Philosophical Association 1, no. 1 (2015): 121–40. http://dx.doi.org/10.1017/apa.2014.23.
Анотація:
ABSTRACT:Nietzsche, we are often told, had an account of ‘self’ or ‘mind’ or a ‘philosophical psychology’, in which what he calls our ‘drives’ play a highly significant role. This underpins not merely his understanding of mind—in particular, of consciousness and action—but also his positive ethics, be they understood as authenticity, freedom, (self-)knowledge, autonomy, self-creation, or power. But Nietzsche did not have anything like a coherent account of ‘the drives’ according to which the self, the relationship between thought and action, or consciousness could be explained; consequently, he did not have a stable account of drives on which his positive ethics could rest. By this, I do not mean that his account is incomplete or that it is philosophically indefensible: both would leave open, misleadingly, the possibility of a rational reconstruction of Nietzsche's views; both would already assume more unity and coherence than we find in his texts. Specifically, as I show through detailed analysis, Nietzsche provides varied and inconsistent accounts of (1) what a ‘drive’ is, (2) how much we can know about drives, and (3) the relationship between drives and conscious deliberations about action. I conclude by questioning the hunt for a Nietzschean theory: is this the best way to be reading him?
20
Fazan, Rubens, Mauro de Oliveira, Valdo José Dias da Silva, Luis Fernando Joaquim, Nicola Montano, Alberto Porta, Mark W. Chapleau, and Helio C. Salgado. "Frequency-dependent baroreflex modulation of blood pressure and heart rate variability in conscious mice." American Journal of Physiology-Heart and Circulatory Physiology 289, no. 5 (November 2005): H1968—H1975. http://dx.doi.org/10.1152/ajpheart.01224.2004.
Анотація:
The goal of this study was to determine the baroreflex influence on systolic arterial pressure (SAP) and pulse interval (PI) variability in conscious mice. SAP and PI were measured in C57Bl/6J mice subjected to sinoaortic deafferentation (SAD, n = 21) or sham surgery ( n = 20). Average SAP and PI did not differ in SAD or control mice. In contrast, SAP variance was enhanced (21 ± 4 vs. 9.5 ± 1 mmHg2) and PI variance reduced (8.8 ± 2 vs. 26 ± 6 ms2) in SAD vs. control mice. High-frequency (HF: 1–5 Hz) SAP variability quantified by spectral analysis was greater in SAD (8.5 ± 2.0 mmHg2) compared with control (2.5 ± 0.2 mmHg2) mice, whereas low-frequency (LF: 0.1–1 Hz) SAP variability did not differ between the groups. Conversely, LF PI variability was markedly reduced in SAD mice (0.5 ± 0.1 vs. 10.8 ± 3.4 ms2). LF oscillations in SAP and PI were coherent in control mice (coherence = 0.68 ± 0.05), with changes in SAP leading changes in PI (phase = −1.41 ± 0.06 radians), but were not coherent in SAD mice (coherence = 0.08 ± 0.03). Blockade of parasympathetic drive with atropine decreased average PI, PI variance, and LF and HF PI variability in control ( n = 10) but had no effect in SAD ( n = 6) mice. In control mice, blockade of sympathetic cardiac receptors with propranolol increased average PI and decreased PI variance and LF PI variability ( n = 6). In SAD mice, propranolol increased average PI ( n = 6). In conclusion, baroreflex modulation of PI contributes to LF, but not HF PI variability, and is mediated by both sympathetic and parasympathetic drives in conscious mice.
21
FENG, XIAOQIN, and ZHIGANG ZHENG. "COHERENT RESONANCE AND PHASE LOCKING IN NOISE-DRIVEN EXCITABLE SYSTEMS." International Journal of Modern Physics B 19, no. 22 (September 10, 2005): 3501–9. http://dx.doi.org/10.1142/s0217979205032188.
Анотація:
The dynamical responses of an excitable FitzHugh–Nagumo (FHN) system under the drive of an external noise are studied. Noise can induce a sequence of firings. The n:m coherent resonance of the FHN oscillator with an intrinsic natural frequency is shown. This effect is discussed by resorting to the phase dynamics of a spike train and the phase synchronization index γnm.
22
Miranda, Rodrigo A., Abraham C. L. Chian, Erico L. Rempel, and Suzana S. A. Silva. "Coherent structures and magnetic reconnection in photospheric and interplanetary magnetic field turbulence." Proceedings of the International Astronomical Union 15, S354 (June 2019): 351–54. http://dx.doi.org/10.1017/s1743921320000113.
Анотація:
AbstractIn this paper it is shown that rope-rope magnetic reconnection in the solar wind can enhance multifractality in the inertial subrange and drive intermittent magnetic field turbulence. Additionally, it is shown that Lagrangian coherent structures can unveil the transport barriers of magnetic elements in the quiet Sun.
23
Laine, Christopher M., Francesco Negro, and Dario Farina. "Neural correlates of task-related changes in physiological tremor." Journal of Neurophysiology 110, no. 1 (July 1, 2013): 170–76. http://dx.doi.org/10.1152/jn.00041.2013.
Анотація:
Appropriate control of muscle contraction requires integration of command signals with sensory feedback. Sensorimotor integration is often studied under conditions in which muscle force is controlled with visual feedback. While it is known that alteration of visual feedback can influence task performance, the underlying changes in neural drive to the muscles are not well understood. In this study, we characterize the frequency content of force fluctuations and neural drive when production of muscle force is target guided versus self guided. In the self-guided condition, subjects performed isometric contractions of the first dorsal interosseous (FDI) muscle while slowly and randomly varying their force level. Subjects received visual feedback of their own force in order to keep contractions between 6% and 10% of maximum voluntary contraction (MVC). In the target-guided condition, subjects used a display of their previously generated force as a target to track over time. During target tracking, force tremor increased significantly in the 3–5 and 7–9 Hz ranges, compared with self-guided contractions. The underlying changes in neural drive were assessed by coherence analysis of FDI motor unit activity. During target-guided force production, pairs of simultaneously recorded motor units showed less coherent activity in the 3–5 Hz frequency range but greater coherence in the 7–9 Hz range than in the self-guided contractions. These results show that the frequency content of common synaptic input to motoneurons is altered when force production is visually guided. We propose that a change in stretch-reflex gain could provide a potential mechanism for the observed changes in force tremor and motor unit coherence.
24
Atia, Yosi, Yonathan Oren, and Nadav Katz. "Robust Diabatic Grover Search by Landau–Zener–Stückelberg Oscillations." Entropy 21, no. 10 (September 25, 2019): 937. http://dx.doi.org/10.3390/e21100937.
Анотація:
Quantum computation by the adiabatic theorem requires a slowly-varying Hamiltonian with respect to the spectral gap. We show that the Landau–Zener–Stückelberg oscillation phenomenon, which naturally occurs in quantum two-level systems under non-adiabatic periodic drive, can be exploited to find the ground state of an N-dimensional Grover Hamiltonian. The total runtime of this method is O ( 2 n ) , which is equal to the computational time of the Grover algorithm in the quantum circuit model. An additional periodic drive can suppress a large subset of Hamiltonian control errors by using coherent destruction of tunneling, thus outperforming previous algorithms.
25
S, Alqahtani Saeed, Toufique A. Soomro, Nisar Ahmed Jandan, Ahmed Ali, Muhammad Irfan, Saifur Rahman, Waleed A. Aldhabaan, Abdulrahman Samir Khairallah, and Ismail Abuallut. "Impact of Retinal Vessel Image Coherence on Retinal Blood Vessel Segmentation." Electronics 12, no. 2 (January 12, 2023): 396. http://dx.doi.org/10.3390/electronics12020396.
Анотація:
Retinal vessel segmentation is critical in detecting retinal blood vessels for a variety of eye disorders, and a consistent computerized method is required for automatic eye disorder screening. Many methods of retinal blood vessel segmentation are implemented, but these methods only yielded accuracy and lack of good sensitivity due to the coherence of retinal blood vessel segmentation. Another main factor of low sensitivity is the proper technique to handle the low-varying contrast problem. In this study, we proposed a five-step technique for assessing the impact of retinal blood vessel coherence on retinal blood vessel segmentation. The proposed technique for retinal blood vessels involved four steps and is known as the preprocessing module. These four stages of the pre-processing module handle the retinal image process in the first stage, uneven illumination and noise issues using morphological operations in the second stage, and image conversion to grayscale using principal component analysis (PCA) in the third step. The fourth step is the main step of contributing to the coherence of retinal blood vessels using anisotropic diffusion filtering and testing their different schemes and get a better coherent image on the optimized anisotropic diffusion filtering. The last step included double thresholds with morphological image reconstruction techniques to produce a segmented image of the vessel. The performances of the proposed method are validated on the publicly available database named DRIVE and STARE. Sensitivity values of 0.811 and 0.821 on STARE and DRIVE respectively meet and surpass other existing methods, and comparable accuracy values of 0.961 and 0.954 on STARE and DRIVE databases to existing methods. This proposed new method for retinal blood vessel segmentations can help medical experts diagnose eye disease and recommend treatment in a timely manner.
26
Rudakova, Hanna, Oksana Polyvoda, and Anton Omelchuk. "Using Recurrent Procedures in Adaptive Control System for Identify the Model Parameters of the Moving Vessel on the Cross Slipway." Data 3, no. 4 (December 7, 2018): 60. http://dx.doi.org/10.3390/data3040060.
Анотація:
The article analyses the problems connected with ensuring the coordinated operation of slipway drives that arise during the launch of a ship. The dynamic model of load of the electric drive of the ship’s cart is obtained taking into account the peculiarities of the construction of the ship-lifting complex, which allows us to analyse the influence of external factors and random influences during the entire process of launching the ship. A linearized mathematical model of the dynamics of a complex vessel movement in the process of descent in the space of states is developed, which allows us to identify the mode of operation of the multi-drive system, taking into account its structure. The analysis of application efficiency of recurrent methods for identification (stochastic approximation and least squares) of the linearized model parameters in the space of states is carried out. A decision support system has been developed in the automated system of operational control by the module for estimating the situation and the control synthesis to ensure a coherent motion of a complex ship-carts object in a two-phase environment.
27
Jeka, John, Kelvin Oie, Gregor Schöner, Tjeerd Dijkstra, and Elaine Henson. "Position and Velocity Coupling of Postural Sway to Somatosensory Drive." Journal of Neurophysiology 79, no. 4 (April 1, 1998): 1661–74. http://dx.doi.org/10.1152/jn.1998.79.4.1661.
Анотація:
Jeka, John, Kelvin Oie, Gregor Schöner, Tjeerd Dijkstra, and Elaine Henson. Position and velocity coupling of postural sway to somatosensory drive. J. Neurophysiol. 79: 1661–1674, 1998. Light touch contact of a fingertip to a stationary surface provides orientation information that enhances control of upright stance. Slight changes in contact force at the fingertip lead to sensory cues about the direction of body sway, allowing attenuation of sway. In the present study, the coupling of postural sway to a moving contact surface was investigated in detail. Head, center of mass, and center of pressure displacement were measured as the contact surface moved rhythmically at 0.1, 0.2, 0.4, 0.6, and 0.8 Hz. Stimulus amplitude decreased with frequency to maintain peak velocity constant across frequency. Head and body sway were highly coherent with contact surface motion at all frequencies except 0.8 Hz, where a drop-off in coherence was observed. Mean frequency of head and body sway matched the driving frequency ≤0.4 Hz. At higher frequencies, non-1:1 coupling was evident. The phase of body sway relative to the touch plate averaged 20–30° at 0.1-Hz drive and decreased approximately linearly to −130° at 0.8-Hz drive. System gain was ∼1 across frequency. The large phase lags observed cannot be accounted for with velocity coupling alone but indicate that body sway also was coupled to the position of the touch plate. Fitting of a linear second-order model to the data suggests that postural control parameters are not fixed but adapt to the moving frame of reference. Moreover, coupling to both position and velocity suggest that a spatial reference frame is defined by the somatosensory system.
28
Nehra, Monika, and Deepak Kedia. "Design of Optical I/Q Modulator Using Dual-drive Mach-Zehnder Modulators in Coherent Optical-OFDM System." Journal of Optical Communications 39, no. 2 (April 25, 2018): 155–59. http://dx.doi.org/10.1515/joc-2016-0089.
Анотація:
AbstractA CO-OFDM system combines the advantages of both coherent detection and OFDM modulation for future high speed fiber transmission. In this paper, we propose an I/Q modulation technique using dual-drive MZMs for high rate 10 Gb/s CO-OFDM system. The proposed modulator provides 10.63 dBm improved optical spectra compared to a single dual-drive MZM. The simulation results in terms of BER and Q factor are quite satisfactory upto a transmission reach of 3,000 km and that to without making use of any dispersion compensation. A BER of about 8.03×10−10and 15.06 dB Q factor have been achieved at −10.43 dBm received optical power.
29
MANNA, MARCELLO, and ANDREA VACCA. "Torque reduction in Taylor–Couette flows subject to an axial pressure gradient." Journal of Fluid Mechanics 639 (October 13, 2009): 373–401. http://dx.doi.org/10.1017/s0022112009991078.
Анотація:
The paper investigates the phenomena occurring in a Taylor–Couette flow system subject to a steady axial pressure gradient in a small envelope of the Taylor–Reynolds state space under transitional regimes. A remarkable net power reduction necessary to simultaneously drive the two flows compared to that required to drive the Taylor–Couette flow alone is documented under non-trivial conditions. The energy transfer process characterizing the large-scale coherent structures is investigated by processing a set of statistically independent realizations obtained from direct numerical simulation. The analysis is conducted with an incompressible three-dimensional Navier–Stokes flow solver employing a spectral representation of the unknowns.
30
JACOBSON, STUART A., and WILLIAM C. REYNOLDS. "Active control of streamwise vortices and streaks in boundary layers." Journal of Fluid Mechanics 360 (April 10, 1998): 179–211. http://dx.doi.org/10.1017/s0022112097008562.
Анотація:
Coherent structures play an important role in the dynamics of turbulent shear flows. The ability to control coherent structures could have significant technological benefits with respect to flow phenomena such as skin friction drag, transition, mixing, and separation. This paper describes the development of an actuator concept that could be used in large arrays for actively controlling transitional and turbulent boundary layers. The actuator consists of a piezoelectrically driven cantilever mounted flush with the flow wall. When driven, the resulting flow disturbance over the actuator is a quasi-steady pair of counter-rotating streamwise vortices with common-flow away from the wall. The vortices decay rapidly downstream of the actuator; however, they produce a set of high- and low-speed streaks that persist far downstream (well over 40 displacement thicknesses). The amplitude of the actuator drive signal controls the strength of the generated vortices. The actuator is fast, compact, and generates a substantial disturbance in the flow. Its performance has been demonstrated using a small array of sensors and actuators in low-speed water laminar boundary layers with imposed steady and unsteady disturbances. Experiments are reported in which transition from a large disturbance was delayed by 40 displacement thicknesses, and in which the mean and spanwise variation of wall shear under an array of high- and low-speed streaks was substantially reduced downstream of a single transverse array of actuators.
31
Carraro-Haddad, I., D. L. Chafatinos, A. S. Kuznetsov, I. A. Papuccio-Fernández, A. A. Reynoso, A. Bruchhausen, K. Biermann, P. V. Santos, G. Usaj, and A. Fainstein. "Solid-state continuous time crystal in a polariton condensate with a built-in mechanical clock." Science 384, no. 6699 (May 31, 2024): 995–1000. http://dx.doi.org/10.1126/science.adn7087.
Анотація:
Time crystals (TCs) are many-body systems that display spontaneous breaking of time translation symmetry. We demonstrate a TC by using driven-dissipative condensates of microcavity exciton-polaritons, spontaneously formed from an incoherent particle bath. The TC phases are controlled by the power of a continuous-wave nonresonant optical drive exciting the condensate and the interaction with cavity phonons. Those phases are, for increasing power, Larmor-like precession of the condensate pseudo-spins—a signature of continuous TC; locking of the frequency of precession to self-sustained coherent phonons—stabilized TC; and doubling of TC’s period by phonons—a discrete TC with continuous excitation. These results establish microcavity polaritons as a platform for the investigation of time-broken symmetry in nonhermitian systems.
32
Journal, Baghdad Science. "Comparison between Direct and Coherent Optical Communication System." Baghdad Science Journal 8, no. 2 (June 12, 2011): 479–84. http://dx.doi.org/10.21123/bsj.8.2.479-484.
Анотація:
The work in this paper focuses on the system quality of direct and coherent communication system for two computers. A system quality is represented by Signal to Noise ratio (SNR) and Bit Error Rate (BER). First part of the work includes implementation of direct optical fiber communication system and measure the system quality .The second part of the work include implementation both the( homodyne and heterodyne)coherent optical fiber communication system and measure the system quality . Laser diode 1310 nm wavelength with its drive circuit used in the transmitter circuit . A single mode of 62.11 km optical fiber is selected as transmission medium . A PIN photo detector is used in the receiver circuit. The optical D-coupler was used to combine the optical signal that come from transmitter laser source with optical signal of laser local oscillator at 1310/1550 nm to obtain coherent detection . Results show that for direct detection the SNR and the BER (28.5 dB, 9.64x10-8,) respectively, while for homodyne and heterodyne coherent detection , the SNR(94.36,97.71)dB and the BER are (1.32x10-22,2.43x10-23) at maximum optical fiber length at 62.11 km. Results show that the homodyne and heterodyne detection are better than direct detection because the large output SNR and low BER of the received signal.
33
Kbashi, Hani J., Samar Y. Al-dabag, and Hadeel A. Hameed. "Comparison between Direct and Coherent Optical Communication System." Baghdad Science Journal 8, no. 2 (June 12, 2011): 479–84. http://dx.doi.org/10.21123/bsj.2011.8.2.479-484.
Анотація:
The work in this paper focuses on the system quality of direct and coherent communication system for two computers. A system quality is represented by Signal to Noise ratio (SNR) and Bit Error Rate (BER). First part of the work includes implementation of direct optical fiber communication system and measure the system quality .The second part of the work include implementation both the( homodyne and heterodyne)coherent optical fiber communication system and measure the system quality . Laser diode 1310 nm wavelength with its drive circuit used in the transmitter circuit . A single mode of 62.11 km optical fiber is selected as transmission medium . A PIN photo detector is used in the receiver circuit. The optical D-coupler was used to combine the optical signal that come from transmitter laser source with optical signal of laser local oscillator at 1310/1550 nm to obtain coherent detection . Results show that for direct detection the SNR and the BER (28.5 dB, 9.64x10-8,) respectively, while for homodyne and heterodyne coherent detection , the SNR(94.36,97.71)dB and the BER are (1.32x10-22,2.43x10-23) at maximum optical fiber length at 62.11 km. Results show that the homodyne and heterodyne detection are better than direct detection because the large output SNR and low BER of the received signal.
34
Ahrens, Kurt F., and David Kleinfeld. "Current Flow in Vibrissa Motor Cortex Can Phase-Lock With Exploratory Rhythmic Whisking in Rat." Journal of Neurophysiology 92, no. 3 (September 2004): 1700–1707. http://dx.doi.org/10.1152/jn.00020.2004.
Анотація:
Rats explore their environment with rhythmic sweeps of their mystacial vibrissae in the range of 5–15 Hz. We tested if vibrissa primary motor (M1) cortex produces electrical activity that locks to this behavioral output. Rats were trained to whisk in air in search of a food reward. The EMG of the mystacial pad served as a surrogate of vibrissa position, while chronically implanted, 16-channel Si-based probes provided a record of field potentials throughout the depth of vibrissa M1 cortex as well as vibrissa primary somatosensory (S1) cortex. The measured potentials were used to estimate the current source density along the radial axis. We observed that current flow throughout the depth of M1 cortex is coherent with the mystacial EMG, i.e., the two signals co-vary with a defined phase relation. This coherence persists after transection of the infraorbital branch (IoN) of the trigeminal nerve, which provides the sole sensory input from the vibrissae. Furthermore, current flow in vibrissa S1 cortex that is coherent with the mystacial EMG also persists after transection of the IoN, consistent with anatomical pathways between M1 and S1. In combination with a previous observation that rhythmic, intracortical microstimulation of vibrissa M1 cortex can drive normal whisking motion, the present data support the hypothesis that, in principle, M1 cortex can initiate motion of the vibrissae on a cycle-by-cycle basis.
35
Stephan, Andreas. "Does the EU's Drive for Private Enforcement of Competition Law Have a Coherent Purpose?" University of Queensland Law Journal 37, no. 1 (May 18, 2020): 153–68. http://dx.doi.org/10.38127/uqlj.v37i1.4145.
Анотація:
The Competition Laws of the European Union (‘EU’) have been a major influence on countless jurisdictions around the world, but their strength as a public enforcement regime have always contrasted with a perceived absence of private enforcement. Private parties cannot bring an action for damages or injunctive relief before EU courts. They can only make a complaint to the European Commission or National Competition Authority, to investigate an infringement of competition law, on their behalf. Therefore, a party’s ability to recover damages falls on the national tort and civil liability rules of each Member State. Although most European legal systems can broadly be described as belonging to the civil law tradition, there are significant differences in procedure and legal culture when it comes to recovering damages. It is also important to remember that the EU has continued to grow in the last fifteen years, with the accession of ten new Member States in 2004, and a further three between 2007 and 2013. These include states that have made a rapid transition from centrally planned economies and Communist-era legal systems.
36
Landi, Alessandro, Raffaele Borrelli, Amedeo Capobianco, and Andrea Peluso. "Transient and Enduring Electronic Resonances Drive Coherent Long Distance Charge Transport in Molecular Wires." Journal of Physical Chemistry Letters 10, no. 8 (April 2, 2019): 1845–51. http://dx.doi.org/10.1021/acs.jpclett.9b00650.
37
Moore, F. L., L. S. Brown, D. L. Farnham, S. Jeon, P. B. Schwinberg, and R. S. Van Dyck. "Cyclotron resonance with10−11resolution: Anharmonic detection and beating a coherent drive with the noise." Physical Review A 46, no. 5 (September 1, 1992): 2653–67. http://dx.doi.org/10.1103/physreva.46.2653.
38
Popp, Wjatscheslaw, Dominik Brey, Robert Binder, and Irene Burghardt. "Quantum Dynamics of Exciton Transport and Dissociation in Multichromophoric Systems." Annual Review of Physical Chemistry 72, no. 1 (April 20, 2021): 591–616. http://dx.doi.org/10.1146/annurev-physchem-090419-040306.
Анотація:
Due to the subtle interplay of site-to-site electronic couplings, exciton delocalization, nonadiabatic effects, and vibronic couplings, quantum dynamical studies are needed to elucidate the details of ultrafast photoinduced energy and charge transfer events in organic multichromophoric systems. In this vein, we review an approach that combines first-principles parameterized lattice Hamiltonians with accurate quantum dynamical simulations using advanced multiconfigurational methods. Focusing on the elementary transfer steps in organic functional materials, we address coherent exciton migration and creation of charge transfer excitons in homopolymers, notably representative of the poly(3-hexylthiophene) material, as well as exciton dissociation at polymer:fullerene heterojunctions. We emphasize the role of coherent transfer, trapping effects due to high-frequency phonon modes, and thermal activation due to low-frequency soft modes that drive a diffusive dynamics.
39
Al-Dolaimy, F., M. H. Kzar, N. Y. Jamil, M. Zaid, F. A. Rasen, S. Hussain, K. Al-Majdi, K. S. Mohsen, A. H. Alawadi, and A. Alsaalamy. "Operating mode dependent energy transfer efficiency in a quantum well waveguide." Laser Physics 33, no. 10 (September 7, 2023): 106001. http://dx.doi.org/10.1088/1555-6611/acf4e4.
Анотація:
Abstract In this paper, we delve into the intricate interplay between optical fields with varying relative phases in a closed-loop configuration semiconductor quantum well waveguide with four distinct energy levels, and how it impacts the Fraunhofer diffraction patterns obtained via four-wave mixing. By harnessing a strong control field, a standing wave driving field, and two weak probe and signal fields, we drive the waveguide to generate these patterns with maximum efficiency. To achieve this, we consider three distinct light-matter interaction scenarios, where the system is first set up in either a lower electromagnetically induced transparency or a coherent population trapping state, followed by a final state that enables electron spin coherence (ESC) induction. Our results reveal that the efficiency of Fraunhofer diffraction in the quantum well waveguide can be enhanced significantly under specific parameter regimes via the spin coherence effect. Further investigation of the light-matter interaction in the ESC zone, where only one of the control fields is a standing wave field, demonstrates that spin coherence facilitates more efficient transfer of energy from the probe light to the third and fourth orders, highlighting its crucial role in shaping the diffraction patterns.
40
Borysenko, V. F., V. A. Sydorov, and A. I. Zemliansky. "INITIAL DATA FOR ANALYSIS OF ELECTROMECHANICAL SYSTEM THE INTERCONNECTED STANDS." Mining science and technology, no. 4 (February 28, 2018): 40–50. http://dx.doi.org/10.17073/2500-0632-2017-4-40-48.
Анотація:
For continuous rolling mills one of the most important technical issues is to configure the speed interrelated stands line. The basic law when setting speed rolling of the group of sequentially connected mill stands is the constancy of the volume of rolled metal S1*V1=S2*V2=S3*V3=...=SiVi . Setting the desired coherent frequencies of rotation of the rolls carried by the mill operator with the drive control specific panel. The electric drive system driven Converter (TP) – DC motor (D) with independent excitation allows operation in two zones (nн>n>n0), which gives the possibility of rapid adjustment of speed of rolling, in violation of the law of constancy of volume rolled. Construction properties of different groups of stands (roughing, intermediate, finishing) can have a considerable effect on the dynamic interaction and, as a consequence, loads on the interconnected Electromechanical systems stands. To assess the interaction of Electromechanical systems of interconnected mill stands it is recommended to first conduct a research on mathematical models to identify the most loaded units with their further study on a real mill using the methods of thermal and vibration field.
41
Wu, Jian-Dong, Zhi Cheng, Xiang-Yu Ye, Zhao-Kai Li, Peng-Fei Wang, Chang-Lin Tian, and Hong-Wei Cheng. "Coherent electrical control of a single electron spin in diamond nitrogen-vacancy centers." Acta Physica Sinica 71, no. 11 (2022): 1. http://dx.doi.org/10.7498/aps.70.20220410.
Анотація:
The nitrogen-vacancy (NV) color center quantum system in diamond has shown great application potential in the fields of solid-state quantum computing and quantum precision measurement because of its unique advantages such as single-spin addressing and manipulation and long quantum coherence time at room temperature. The precise manipulation technology of single spin is particularly important for the development of the application of NV center. The common spin manipulation methods used in NV center quantum system are to drive and manipulate the electron spin by resonant alternating magnetic field. In recent years, the electrical control of quantum spin has attracted extensive attention. In this paper, the use of alternating electric field to control the electron spin of NV center has been studied. The alternating electric field generated by the electrode successfully drives the Rabi oscillation of the NV center spin between the <inline-formula><tex-math id="M4">\begin{document}$\Delta m_s=\pm2$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20220410_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20220410_M4.png"/></alternatives></inline-formula> magnetic-dipole forbidden energy levels of <inline-formula><tex-math id="M5">\begin{document}$|m_s=-1\rangle$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20220410_M5.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20220410_M5.png"/></alternatives></inline-formula> and <inline-formula><tex-math id="M6">\begin{document}$|m_s=+1\rangle$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20220410_M6.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20220410_M6.png"/></alternatives></inline-formula>. Further studies show that the frequency of the electrically driven Rabi oscillation is controlled by the power of the driven electric field and independent of the resonant frequency of the electric field. The combination of spin electric control and magnetic control technology can realize the full manipulation of the direct transition between the three spin energy levels of NV center, thus promoting the development of the research and applications of NV quantum system in the fields of quantum simulation, quantum computing, precision measurement of electromagnetic field and so on.
42
Wu, Kaijun, Huan Zheng, and Tao Li. "Coherence Resonance Behavior of FitzHugh-Nagumo Neurons Induced by Electromagnetic Field Driven by Phase Noise." Discrete Dynamics in Nature and Society 2022 (January 27, 2022): 1–18. http://dx.doi.org/10.1155/2022/8384444.
Анотація:
Noise exists widely in the nervous system, and plays a crucial role in the nervous system information processing. Noise can not only enhance but also weaken the ability of the nervous system to process information. Neurons are in a complex and variable electromagnetic field. Electromagnetic induction plays an important role in regulating the changes of neuronal membrane potential. Therefore, this paper simulates the electromagnetic field environment of the nervous system with a memristor and analyses the rich coherence resonance behavior of FitzHugh-Nagumo (FHN) neuron system under the drive of phase noise. By taking the amplitude, period and noise intensity of phase noise as the main parameters and the parameters of memristor as auxiliary parameters, the two-parameter changes are made from the angle of the amplitude and period of phase noise, the amplitude and intensity of phase noise, and the noise intensity and period of phase noise, respectively. The dynamic behaviors of coherent resonance of FHN neuron system are analyzed from the amplitude and period, amplitude and intensity as well as intensity and period of phase noise, respectively. When the amplitude and period of the phase noise and the intensity and period of the phase noise are used as independent variables for the two-parameter analysis, the FHN neuron system shows rich dynamic behaviors such as coherence mono-resonance, coherence bi-resonance and coherence multi-resonance. Especially when the amplitude and period of phase noise change as two-parameter, the system presents a coherence resonance of discharge pattern with period-adding cluster discharge at the valley. When the amplitude and intensity of phase noise are taken as independent variables for two-parameter analysis, FHN neuronal system presents single or dual coherence resonance at any value of noise intensity with the change of phase noise amplitude. The simulated results show that the FHN neuron system demonstrates rich coherence resonance behaviors under the drive of phase noise when the effect of electromagnetic induction in the nervous system is simulated by memristor.
43
Pinna, G. D., R. Maestri, A. Mortara, and M. T. La Rovere. "Cardiorespiratory interactions during periodic breathing in awake chronic heart failure patients." American Journal of Physiology-Heart and Circulatory Physiology 278, no. 3 (March 1, 2000): H932—H941. http://dx.doi.org/10.1152/ajpheart.2000.278.3.h932.
Анотація:
We applied spectral techniques to the analysis of cardiorespiratory signals [instantaneous lung volume (ILV), instantaneous tidal volume (ITV), arterial O2 saturation ([Formula: see text]) at the ear, heart rate (HR), systolic (SAP), and diastolic (DAP) arterial pressure] during nonapneic periodic breathing (PB) in 29 awake chronic heart failure (CHF) patients and estimated the timing relationships between respiratory and slow cardiovascular (<0.04 Hz) oscillations. Our aim was 1) to elucidate major mechanisms involved in cardiorespiratory interactions during PB and 2) to test the hypothesis of a central vasomotor origin of PB. All cardiovascular signals were characterized by a dominant (≥84% of total power) oscillation at the frequency of PB (mean ± SE: 0.022 ± 0.0008 Hz), highly coherent (≥0.89), and delayed with respect to ITV (ITV-HR, 2.4 ± 0.72 s; ITV-SAP, 6.7 ± 0.65 s; ITV-DAP, 3.2 ± 0.61 s; P < 0.01). [Formula: see text] was highly coherent with (coherence function = 0.96 ± 0.009) and almost opposite in phase to ITV. These findings demonstrate the existence of a generalized cardiorespiratory rhythm led by the ventilatory oscillation and suggest that 1) the cyclic increase in inspiratory drive and cardiopulmonary reflexes and 2) mechanical effects of PB-induced changes in intrathoracic pressure are the more likely sources of the HR and blood pressure oscillations, respectively. The timing relationship between ITV and blood pressure signals excludes the possibility that PB represents the effect of a central vasomotor rhythm.
44
Gasperino, David, Ted Baughman, Helen V. Hsieh, David Bell, and Bernhard H. Weigl. "Improving Lateral Flow Assay Performance Using Computational Modeling." Annual Review of Analytical Chemistry 11, no. 1 (June 12, 2018): 219–44. http://dx.doi.org/10.1146/annurev-anchem-061417-125737.
Анотація:
The performance, field utility, and low cost of lateral flow assays (LFAs) have driven a tremendous shift in global health care practices by enabling diagnostic testing in previously unserved settings. This success has motivated the continued improvement of LFAs through increasingly sophisticated materials and reagents. However, our mechanistic understanding of the underlying processes that drive the informed design of these systems has not received commensurate attention. Here, we review the principles underpinning LFAs and the historical evolution of theory to predict their performance. As this theory is integrated into computational models and becomes testable, the criteria for quantifying performance and validating predictive power are critical. The integration of computational design with LFA development offers a promising and coherent framework to choose from an increasing number of novel materials, techniques, and reagents to deliver the low-cost, high-fidelity assays of the future.
45
Yin, Wen, G. F. Zhang, Y. Z. Lai, and Q. W. Yan. "The oscillation of the coherent light between photonic quantum wells with time-dependent coupling drive." Optics Communications 225, no. 1-3 (September 2003): 7–11. http://dx.doi.org/10.1016/j.optcom.2003.07.027.
46
Li, Q., M. Yang, C. Klewe, P. Shafer, A. T. N’Diaye, D. Hou, T. Y. Wang, et al. "Coherent ac spin current transmission across an antiferromagnetic CoO insulator." Nature Communications 10, no. 1 (November 20, 2019). http://dx.doi.org/10.1038/s41467-019-13280-5.
Анотація:
AbstractThe recent discovery of spin current transmission through antiferromagnetic insulating materials opens up vast opportunities for fundamental physics and spintronics applications. The question currently surrounding this topic is: whether and how could THz antiferromagnetic magnons mediate a GHz spin current? This mismatch of frequencies becomes particularly critical for the case of coherent ac spin current, raising the fundamental question of whether a GHz ac spin current can ever keep its coherence inside an antiferromagnetic insulator and so drive the spin precession of another ferromagnet layer coherently? Utilizing element- and time-resolved x-ray pump-probe measurements on Py/Ag/CoO/Ag/Fe75Co25/MgO(001) heterostructures, here we demonstrate that a coherent GHz ac spin current pumped by the Py ferromagnetic resonance can transmit coherently across an antiferromagnetic CoO insulating layer to drive a coherent spin precession of the Fe75Co25 layer. Further measurement results favor thermal magnons rather than evanescent spin waves as the mediator of the coherent ac spin current in CoO.
47
"Lasers drive coherent terahertz radiation." Physics World 29, no. 7 (July 2016): 5. http://dx.doi.org/10.1088/2058-7058/29/7/9.
48
Brand, Helmut R., and Harald Pleiner. "External concentration gradients can drive a propagating wave in a coherently layered system of nanosheets." Journal of Chemical Physics 159, no. 6 (August 8, 2023). http://dx.doi.org/10.1063/5.0159992.
Анотація:
We present a model for the dynamics observed recently by Sano et al. [Nat. Commun. 12, 6771 (2021)] in a coherently layered system made up of sheetlike colloidal particles (nanosheets) subjected to an external concentration gradient. Adding a new macroscopic variable characteristic for the nonequilibrium situation encountered in the experiments to the hydrodynamics of smectic A liquid crystals, we show that all salient dynamic features observed in the experiments can be accounted for. For this nonequilibrium phenomenon, we identify the symmetry of the underlying ground state as undulating smectic A-like layering and the applied concentration gradient applied in the layer planes as the nonequilibrium driving force. As a result of our analysis, we find a coherent motion of undulating layers generated by a Helfrich–Hurault type instability propagating at a fixed velocity in accordance with the observations. If the coherence of the layering is lost, there is no longer any coherent propagation to be expected—as is also observed.
49
Dey, Anushree, Arpita Pal, Subhasish Dutta Gupta, and Bimalendu Deb. "Zero-threshold correlated-photon laser with a single trapped atom in a bimodal cavity." Physica Scripta, May 12, 2023. http://dx.doi.org/10.1088/1402-4896/acd4f5.
Анотація:
Abstract We demonstrate theoretically the feasibility of correlated entangled photon-pair generation with vanishing threshold in a bimodal cavity setup that uses a single $V$-type three level atom pumped by dual incoherent sources and driven by two coherent fields. The photon-pair is shown to be entangled only for low levels of the incoherent pumps and owes its origin solely to the coherent drives. Our results show that the dual incoherent pumping with no coherent drive can lead to amplification of the cavity fields with strong inter-mode antibunching but no entanglement. We analyse our results in terms of an interplay between coherent and incoherent processes involving cavity-dressed states. Both the inter- and intra-mode Hanbury Brown-Twiss (HBT) functions exhibit temporal oscillations in the strong-coupling cavity QED regime. Our theoretical scheme for the generation of nonclassical and entangled photon pairs may find interesting applications in quantum metrology and quantum information science.
50
NIU, Siyuan, Aida Todri-Sanial, and Nicholas Torleiv Bronn. "Multi-qubit dynamical decoupling for enhanced crosstalk suppression." Quantum Science and Technology, June 20, 2024. http://dx.doi.org/10.1088/2058-9565/ad5a37.
Анотація:
Abstract Dynamical decoupling (DD) is one of the simplest error suppression methods, aiming to enhance the coherence of qubits in open quantum systems. Moreover, DD has demonstrated effectiveness in reducing coherent crosstalk, one major error source in near-term quantum hardware, which manifests from two types of interactions. Static crosstalk exists in various hardware platforms, including superconductor and semiconductor qubits, by virtue of always-on qubit-qubit coupling. Additionally, driven crosstalk may occur as an unwanted drive term due to leakage from driven gates on other qubits. Here we explore a novel staggered DD protocol tailored for multi-qubit systems that suppresses the decoherence error and both types of coherent crosstalk. We develop two experimental setups – an “idle-idle” experiment in which two pairs of qubits undergo free evolution simultaneously and a “driven-idle” experiment in which one pair is continuously driven during the free evolution of the other pair. These experiments are performed on an IBM Quantum superconducting processor and demonstrate the significant impact of the staggered DD protocol in suppressing both types of coherent crosstalk. When compared to the standard DD sequences from state-of-the-art methodologies with the application of X2 sequences, our staggered DD protocol enhances circuit fidelity by 19.7% and 8.5%, respectively, in addressing these two crosstalk types.