Potential Oscillations Research Articles

Correction to “Potential Oscillations during Cobalt–Nickel Electrodeposition in the Presence of Butynediol”

Correction to “Potential Oscillations during Cobalt–Nickel Electrodeposition in the Presence of Butynediol”

Adaptive Immersed Mesh Method (AIMM) for Fluid–Structure Interaction

Our paper proposes an innovative approach for modeling Fluid–Structure Interaction (FSI). Our method combines both traditional monolithic and partitioned approaches, creating a hybrid solution that facilitates FSI. At each time iteration, the solid mesh is immersed within a fluid–solid mesh, all while maintaining its independent Lagrangian hyperelastic solver. The Eulerian mesh encompasses both the fluid and solid components and accommodates various physical phenomena. We enhance the interaction between solid and fluid through anisotropic mesh adaptation and the Level-Set methods. This enables a more accurate representation of their interaction. Together, these components constitute the Adaptive Immersed Mesh Method (AIMM). For both solvers, we utilize the Variational Multi-Scale (VMS) method, mitigating potential spurious oscillations common with piecewise linear tetrahedral elements. The framework operates in 3D with parallel computing capabilities. Our method’s accuracy, robustness, and capabilities are assessed through a series of 2D numerical problems. Furthermore, we present various three-dimensional test cases and compare their results to experimental data.

Studies on Membrane Potential and Ca2+ Oscillations in Rat Carotid Body Type I Cells

Carotid body (CB) glomus cells sense changes in arterial O2 pressure (PO2) and pH, and adjust the secretory and carotid sinus nerve activity and ventilation to help maintain normal levels of blood PO2 and pH. Our recent studies showed that isolated CB cell clusters perfused with physiological buffer solution generate spontaneous Ca2+ oscillations at low frequency in normoxia. Mild and moderate levels of hypoxia (2-5%O2) and acidosis (pHo7.2-7.3) increased the frequency and amplitude of Ca2+ oscillations. Inhibitors of voltage-dependent Ca2+ channels and removal of external Ca2+ abolished Ca2+ oscillations, indicating that Ca2+ influx was critical for generating Ca2+ oscillations. To better understand the phenomenon of Ca2+oscillations in glomus cells, we examined the potential role of oscillations in cell membrane potential (Em) in CB cells in triggering Ca2+ influx and Ca2+ oscillations. Using the cell-attached patch configuration, we assessed cell Em by recording TASK single channels, because a linear relationship exists between TASK amplitude and cell Em. Recording of TASK in CB cells in normoxia showed that many CB cells exhibit oscillations in TASK amplitude, indicating the presence of spontaneous oscillations in cell Em. The oscillation frequency of cell Em was similar to that of Ca2+ oscillations. Oscillations in TASK single channel amplitude were blocked by nifedipine (Ca2+ channel antagonist), by removal of extracellular Ca2+, and by 2-APB (an inhibitor of ER Ca2+ channel and store-operated Ca2+ entry). Mild hypoxia increased the frequency of oscillations of TASK amplitude, indicating that mild hypoxia increased the frequency of cell Em oscillations. These findings suggest that cell Em oscillations (that open voltage-dependent Ca2+ channels and increase Ca2+ influx) are an integral component of the cellular signaling mechanism by which Ca2+ oscillations are produced in CB cells. This work was funded by National Institutes of Health (NIH) grants to D.K. (HL111497) and C.W. (HL142906), and an award from Rosalind Franklin University of Medicine and Science. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Factors Influencing the Fluctuation Amplitude of the H− Ion Beam Extracted from an RF Wave Excited Ion Source Plasma

The beam oscillation of J-PARC ion source is being studied as AC electric field at 2 MHz ion source driving frequency can directly change the extraction characteristics of both H− ions and electrons. The internal RF antenna inducing the electric field generated two peaks of plasma production during one RF cycle as confirmed by 4 MHz modulation of Balmer-alpha (Hα) emission intensity. The coupling between the plasma production at 4 MHz and the oscillation of the local plasma potential in the vicinity of the extraction hole at 2 MHz can cause 6 MHz oscillation, which was observed in the measurement of extraction current from the ion source. Phase-delay of Hα intensities from the source plasma and those of the extraction electron current were compared with the RF input signal to the amplifier.

The second data release from the European Pulsar Timing Array

The European Pulsar Timing Array (EPTA) and Indian Pulsar Timing Array (InPTA) collaborations have measured a low-frequency common signal in the combination of their second and first data releases, respectively, with the correlation properties of a gravitational wave background (GWB). Such a signal may have its origin in a number of physical processes including a cosmic population of inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, cosmic strings, and tensor mode generation by the non-linear evolution of scalar perturbations in the early Universe; and oscillations of the Galactic potential in the presence of ultra-light dark matter (ULDM). At the current stage of emerging evidence, it is impossible to discriminate among the different origins. Therefore, for this paper, we consider each process separately, and investigated the implications of the signal under the hypothesis that it is generated by that specific process. We find that the signal is consistent with a cosmic population of inspiralling SMBHBs, and its relatively high amplitude can be used to place constraints on binary merger timescales and the SMBH-host galaxy scaling relations. If this origin is confirmed, this would be the first direct evidence that SMBHBs merge in nature, adding an important observational piece to the puzzle of structure formation and galaxy evolution. As for early Universe processes, the measurement would place tight constraints on the cosmic string tension and on the level of turbulence developed by first-order phase transitions. Other processes would require non-standard scenarios, such as a blue-tilted inflationary spectrum or an excess in the primordial spectrum of scalar perturbations at large wavenumbers. Finally, a ULDM origin of the detected signal is disfavoured, which leads to direct constraints on the abundance of ULDM in our Galaxy.

Subthalamic nucleus synchronization between beta band local field potential and single-unit activity in Parkinson's disease.

Local field potential (LFP) oscillations in the beta band (13-30 Hz) in the subthalamic nucleus (STN) of Parkinson's disease patients have been implicated in disease severity and treatment response. The relationship between single-neuron activity in the STN and regional beta power changes remains unclear. We used spike-triggered average (STA) to assess beta synchronization in STN. Beta power and STA magnitude at the beta frequency range were compared in three conditions: STN versus other subcortical structures, dorsal versus ventral STN, and high versus low beta power STN recordings. Magnitude of STA-LFP was greater within the STN compared to extra-STN structures along the trajectory path, despite no difference in percentage of the total power. Within the STN, there was a higher percent beta power in dorsal compared to ventral STN but no difference in STA-LFP magnitude. Further refining the comparison to high versus low beta peak power recordings inside the STN to evaluate if single-unit activity synchronized more strongly with beta band activity in areas of high beta power resulted in a significantly higher STA magnitude for areas of high beta power. Overall, these results suggest that STN single units strongly synchronize to beta activity, particularly units in areas ofhigh beta power.

Duality between the quantum inverted harmonic oscillator and inverse square potentials

In this paper we show how the quantum mechanics of the inverted harmonic oscillator (IHO) can be mapped to the quantum mechanics of a particle in a super-critical inverse square potential (ISP). We demonstrate this by relating both of these systems to the Berry–Keating system with Hamiltonian H=(xp+px)/2 . It has long been appreciated that the quantum mechanics of the ISP has an ambiguity in choosing a boundary condition near the origin and we show how this ambiguity is mapped to the IHO system. Imposing a boundary condition requires specifying a distance scale where it is applied and changes to this scale come with a renormalisation group (RG) evolution of the boundary condition that ensures observables do not directly depend on the scale (which is arbitrary). Physical scales instead emerge as RG invariants of this evolution. The RG flow for the ISP is known to follow limit cycles describing the discrete breaking of classical scale invariance in a simple example of a quantum anomaly, and we find that limit cycles also occur for the IHO. However, unlike the ISP where the continuous scaling symmetry is explicit, in the case of the IHO it is hidden and occurs because the Hamiltonian is part of a larger su(1,1) spectrum generating algebra. Our map does not require the boundary condition to be self-adjoint, as can be appropriate for systems that involve the absorption or emission of particles.

Auditory Competition and Coding of Relative Stimulus Strength across Midbrain Space Maps of Barn Owls.

The natural environment challenges the brain to prioritize the processing of salient stimuli. The barn owl, a sound localization specialist, exhibits a circuit called the midbrain stimulus selection network, dedicated to representing locations of the most salient stimulus in circumstances of concurrent stimuli. Previous competition studies using unimodal (visual) and bimodal (visual and auditory) stimuli have shown that relative strength is encoded in spike response rates. However, open questions remain concerning auditory-auditory competition on coding. To this end, we present diverse auditory competitors (concurrent flat noise and amplitude-modulated noise) and record neural responses of awake barn owls of both sexes in subsequent midbrain space maps, the external nucleus of the inferior colliculus (ICx) and optic tectum (OT). While both ICx and OT exhibit a topographic map of auditory space, OT also integrates visual input and is part of the global-inhibitory midbrain stimulus selection network. Through comparative investigation of these regions, we show that while increasing strength of a competitor sound decreases spike response rates of spatially distant neurons in both regions, relative strength determines spike train synchrony of nearby units only in the OT. Furthermore, changes in synchrony by sound competition in the OT are correlated to gamma range oscillations of local field potentials associated with input from the midbrain stimulus selection network. The results of this investigation suggest that modulations in spiking synchrony between units by gamma oscillations are an emergent coding scheme representing relative strength of concurrent stimuli, which may have relevant implications for downstream readout.

Perturbing cortical networks: in vivo electrophysiological consequences of pan-neuronal chemogenetic manipulations using deschloroclozapine.

Chemogenetic techniques, specifically the use of Designer Receptors Exclusively Activated by Designer Drugs (DREADDs), have become invaluable tools in neuroscience research. Yet, the understanding of how Gq- and Gicoupled DREADDs alter local field potential (LFP) oscillations in vivo remains incomplete. This study investigates the in vivo electrophysiological effects of DREADD actuation by deschloroclozapine, on spontaneous firing rate and LFP oscillations recorded from the anterior cingulate cortex in lightly anesthetized male rats. Unexpectedly, in response to the administration of deschloroclozapine, we observed inhibitory effects with pan-neuronal hM3D(Gq) stimulation, and excitatory effects with pan-neuronal hM4D(Gi) stimulation in a significant portion of neurons. These results emphasize the need to account for indirect perturbation effects at the local neuronal network level in vivo, particularly when not all neurons express the chemogenetic receptors uniformly. In the current study, for instance, the majority of cells that were transduced with both hM3D(Gq) and hM4D(Gi) were GABAergic. Moreover, we found that panneuronal cortical chemogenetic modulation can profoundly alter oscillatory neuronal activity, presenting a potential research tool or therapeutic strategy in several neuropsychiatric models and diseases. These findings help to optimize the use of chemogenetic techniques in neuroscience research and open new possibilities for novel therapeutic strategies.

Acetylcholine Engages Distinct Amygdala Microcircuits to Gate Internal Theta Rhythm.

Acetylcholine (ACh) is released from basal forebrain cholinergic neurons in response to salient stimuli and engages brain states supporting attention and memory. These high ACh states are associated with theta oscillations, which synchronize neuronal ensembles. Theta oscillations in the basolateral amygdala (BLA) in both humans and rodents have been shown to underlie emotional memory, yet their mechanism remains unclear. Here, using brain slice electrophysiology in male and female mice, we show large ACh stimuli evoke prolonged theta oscillations in BLA local field potentials that depend upon M3 muscarinic receptor activation of cholecystokinin (CCK) interneurons (INs) without the need for external glutamate signaling. Somatostatin (SOM) INs inhibit CCK INs and are themselves inhibited by ACh, providing a functional SOM→CCK IN circuit connection gating BLA theta. Parvalbumin (PV) INs, which can drive BLA oscillations in baseline states, are not involved in the generation of ACh-induced theta, highlighting that ACh induces a cellular switch in the control of BLA oscillatory activity and establishes an internally BLA-driven theta oscillation through CCK INs. Theta activity is more readily evoked in BLA over the cortex or hippocampus, suggesting preferential activation of the BLA during high ACh states. These data reveal a SOM→CCK IN circuit in the BLA that gates internal theta oscillations and suggest a mechanism by which salient stimuli acting through ACh switch the BLA into a network state enabling emotional memory.

Cell-type-specific representation of spatial context in the rat prefrontal cortex

The ability to represent one's own position in relation to cues, goals, or threats is crucial to successful goal-directed behavior. Using optotagging in knock-in rats expressing Cre recombinase in parvalbumin (PV) neurons (PV-Cre rats), we demonstrate cell-type-specific encoding of spatial and movement variables in the medial prefrontal cortex (mPFC) during goal-directed reward seeking. Single neurons encoded the conjunction of the animal's spatial position and the run direction, referred to as the spatial context. The spatial context was most prominently represented by the inhibitory PV interneurons. Movement toward the reward was signified by increased local field potential (LFP) oscillations in the gamma band but this LFP signature was not related to the spatial information in the neuronal firing. The results highlight how spatial information is incorporated into cognitive operations in the mPFC. The presented PV-Cre line opens the door for expanded research approaches in rats.

Electrochemical oscillation behaviors of gold during its recovery from waste printed circuit boards through slurry electrolysis

Slurry electrolysis is an effective technology for recovering gold from waste printed circuit boards (WPCBs). However, electrochemical oscillation during the gold recovery process is a potential factor affecting power consumption. As a result, the potential oscillation behaviors of gold dissolution at a constant current were studied. These results showed that the periodic formation and dissolution of the Au-OH passive film on the anode induced electrochemical oscillation. The amplitude and frequency of electrochemical oscillation were affected by hydrochloric acid concentration, current intensity, electrode spacing, and sodium chloride concentration, among which the concentration of sodium chloride had a significant inhibitory effect. Under the following conditions: hydrochloric acid concentration of 8 mol/L, current of 0.03 A, and electrode spacing of 1.5 cm, the obtained maximum amplitude potential and frequency were 1.17 V and 0.56 Hz, respectively. The phase space reconstruction results showed that the systems evolved between the near-linear equilibrium region and the periodic oscillation region. Different factors induced two oscillation modes: top-down and bottom-up. The top-down and bottom-up oscillations induced by current intensity, hydrochloric acid concentration, and electrode spacing reduced the relative power consumption by 11.8, 17.2, and 11.8 %, respectively, and increased the relative power consumption by 14.3, 21.2, and 30.1 %, respectively. A critical value was obtained, which varied oscillation patterns and gained a region of lower power consumption. The addition of trisodium citrate and PVP can improve gold recovery rate and current efficiency by regulating process of electrochemical oscillation. This work will provide theoretical support for recovering valuable metals from WPCBs with reduced energy consumption by controlling the external conditions to switch the oscillation mode.

One dimensional Bose–Einstein condensate under the effect of the extended uncertainty principle

In this study, an analytical investigation was conducted to assess the effects of the extended uncertainty principle (EUP) on a Bose–Einstein condensate (BEC) described by the deformed one-dimensional Gross–Pitaevskii equation (GPE). Analytical solutions were derived for null potential while we used variational and numerical methods for a harmonic oscillator potential. The effects of EUP on stability, probability density, position, and momentum uncertainties of BEC are analyzed. The EUP is found to be applicable for the free dark soliton solution and in the presence of a harmonic potential within specific ranges of the deformation parameter α, while it is not valid for the free bright soliton solution.

Confinement of N-Body Systems and Non-integer Dimensions

The squeezing process of a three-dimensional quantum system by use of an external deformed one-body oscillator potential can also be described by the d-method, without external field and where the dimension can take non-integer values. In this work we first generalize both methods to N particles and any transition between dimensions below 3. Once this is done, the use of harmonic oscillator interactions between the particles allows complete analytic solutions of both methods, and a direct comparison between them is possible. Assuming that both methods describe the same process, leading to the same ground state energy and wave function, an analytic equivalence between the methods arises. The equivalence between both methods and the validity of the derived analytic relation between them is first tested for two identical bosons and for squeezing transitions from 3 to 2 and 1 dimensions, as well as from 2 to 1 dimension. We also investigate the symmetric squeezing from 3 to 1 dimensions of a system made of three identical bosons. We have in all the cases found that the derived analytic relations between the two methods work very well. This fact permits to relate both methods also for large squeezing scenarios, where the brute force numerical calculation with the external field is too much demanding from the numerical point of view, especially for systems with more than two particles.

Bound states of relativistic spinless particles in a mix of circularly symmetric vector and scalar harmonic oscillators

We study the dynamics of relativistic spinless particles moving in a plane when there is circular symmetry. The general formalism for solving the Klein–Gordon equation in cylindrical coordinates for such systems is presented, as well as the conserved observables and the corresponding quantum numbers. We look for bound solutions of the corresponding Klein–Gordon equation when one has vector and scalar circularly symmetric harmonic oscillator potentials. Both positive and negative bound solutions are considered when there is either equal vector and scalar potentials or symmetric vector and scalar potentials, and it is shown how both cases are related through charge conjugation. We compute the non-relativistic limit for those cases, and show that for symmetric scalar and vector potentials the limit does not exist in the first order of an harmonic oscillator frequency, recovering a known result from the Dirac equation with the same kind of potentials.

The turbulent jet in the scale-relativity framework

The turbulent jet plays an important role in fluid mechanics since it is a prototype of free turbulent flow which presents many unsolved problems, among which the absence of closure of the governing equations. Despite the chaotic nature of turbulence, it is characterized by the existence of many universal structures, in particular dimensionless invariants such as its opening angle or the correlation coefficient of velocities. After having given new exact solutions of the Reynolds Averaged Navier–Stokes equations (RANS), we suggest a solution to this puzzle in the scale-relativity framework. In this theory, the time derivative of the Navier–Stokes equations is integrated in terms of a macroscopic Schrödinger equation acting in velocity-space. This equation involves a constant ℏv which can be identified with the energy dissipation rate, while the pressure gradient manifests itself as a quantum harmonic oscillator (QHO) potential. The squared modulus of its solutions yields the probability density function (PDF) of velocities. The Reynolds stresses can then be derived from this PDF, so that the closure problem is solved in this case. This allows us to obtain a theoretical prediction for the turbulent intensity radial profile (and therefore for the pressure) which agrees with the experimental data. The ratio of axial over radial velocity fluctuations is found to be R=1.3–1.4 from QHO properties, in good agreement with its experimental values; we theoretically predict a jet opening angle α=1/2R3 accounting for its universal value ≈1/5; the mean ratio of turbulent intensity amplitudes over jet centerline axial velocity is predicted to be X=19/80, in good agreement with its universally measured value ≈1/4; from these parameters we derive possible values of the radial turbulent intensity amplitude μ=0.19–0.22 consistent with experiments; finally, we find a correlation coefficient of velocities ρ=1/R3=2 α, suggesting an explanation for the universal value ≈0.4 observed for the turbulent jet and for all free shear flows.

Protective Effect of Pemafibrate Treatment against Diabetic Retinopathy in Spontaneously Diabetic Torii Fatty Rats.

Diabetic retinopathy (DR) can cause visual impairment and blindness, and the increasing global prevalence of diabetes underscores the need for effective therapies to prevent and treat DR. Therefore, this study aimed to evaluate the protective effect of pemafibrate treatment against DR, using a Spontaneously Diabetic Torii (SDT) fatty rat model of obese type 2 diabetes. SDT fatty rats were fed either a diet supplemented with pemafibrate (0.3 mg/kg/day) for 16 weeks, starting at 8 weeks of age (Pf SDT fatty: study group), or normal chow (SDT fatty: controls). Normal chow was provided to Sprague-Dawley (SD) rats (SD: normal controls). Electroretinography (ERG) was performed at 8 and 24 weeks of age to evaluate the retinal neural function. After sacrifice, retinal thickness, number of retinal folds, and choroidal thickness were evaluated, and immunostaining was performed for aquaporin-4 (AQP4). No significant differences were noted in food consumption, body weight, or blood glucose level after pemafibrate administration. Triglyceride levels were reduced, and high-density lipoprotein cholesterol levels were increased. Extension of oscillatory potential (OP)1 and OP3 waves on ERG was suppressed in the Pf SDT fatty group. Retinal thickness at 1,500 microns from the optic disc improved in the Pf SDT fatty group. No significant improvements were noted in choroidal thickness or number of retinal folds. Quantitative analyses showed that AQP4-positive regions in the retinas were significantly larger in the Pf SDT fatty group than in the SDT fatty group. The findings suggest that pemafibrate treatment can exert protective effects against DR.

Study of thermodynamic properties of N particles in one-dimensional harmonic oscillator potential

We have calculated the partition function and hence the energy and the specific heat of a two-particle system in n numbers of finite nondegenerate energy levels of equal spacing distributed according to classical and quantum statistics. We have then extended our study for N identical particles placed in 1D harmonic oscillator potential. It is observed that the specific heat of bosons and fermions are exactly the same in this potential at any temperature, and at high temperature the results are similar to that for the classical particles. The partition function of a system of two particles placed in 2D harmonic oscillator potential has also been determined as comparison.

Abstract 4705: Repetitive membrane potential oscillations enhance metformin's antiproliferative effect in glioblastoma stem cells

Abstract Glioblastoma (GB) is the most common and lethal brain tumor and there is a general agreement that GB stem cells (GSCs) are primarily responsible for its high aggressiveness and recurrence. It was recently reported that GSCs are enriched in the transmembrane form of CLIC1 protein (tmCLIC1) and its inhibition was shown to impair tumor growth both in vitro and in vivo. IAA94 hampers tmCLIC1 function but could not be used in clinics. However, tmCLIC1 is also sensitive to metformin, the most used drug to treat type-2 diabetes. Metformin has been demonstrated to have the same effect as IAA94 in in vitro experiments, resulting in an antitumoral action on cancer cells. Moreover, GB orthotopic mouse model treated with metformin shows a 50% survival compared to control animals, even if metformin concentration in the mice brain resulted in the nanomolar range. In this scenario, the main aim of this work is to enhance the effect of metformin able to reach the brain, improving its antitumoral activity in GB. The interaction between metformin and tmCLIC1 occurs only when this protein is in its open state. TmCLIC1 has the peculiarity of being a voltage-dependent ion channel that opens at depolarized voltages. Thus, our strategy is to apply electromagnetic field (EMF) stimulation to induce repetitive membrane depolarization, increasing metformin-tmCLIC1 binding. Our results show that EMF stimulation induces the close-to-open transitions of tmCLIC1, resulting in a 10-fold decrease of the operative concentration of Metformin. This was verified initially in vitro with GSC culture and spheroids model and afterward confirmed also in an in vivo model. The project’s long-term goal is to combine transcranial stimulation and metformin administration in patients as an adjuvant therapy able to target cells that are resistant to chemotherapy and drive tumor relapse. Citation Format: Ivan Verduci, Gaetano Cannavale, Guido Rey, Francesca Cianci, Alessandro Fantin, Michele Mazzanti. Repetitive membrane potential oscillations enhance metformin's antiproliferative effect in glioblastoma stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4705.

Electroretinographical Analysis of the Effect of BGP-15 in Eyedrops for Compensating Global Ischemia-Reperfusion in the Eyes of Sprague Dawley Rats.

Retinal vascular diseases and consequential metabolic disturbances in the eye are major concerns for healthcare systems all around the world. BGP-15, a drug candidate small-molecule [O-(3-piperidino-2-hydroxy-1-propyl) nicotinic amidoxime dihydrochloride], has been formerly demonstrated by our workgroup to be retinoprotective both in the short and long term. Based on these results, the present study was performed to investigate the efficacy of BGP in an eyedrop formulation containing sulfobutylether-β-cyclodextrin (SBECD), which is a solubility enhancer as well. Electroretinographical evaluations were carried out and BGP was demonstrated to improve both scotopic and photopic retinal a- and b-waves, shorten their implicit times and restore oscillatory potentials after ischemia-reperfusion. It was also observed to counteract retinal thinning after ischemia-reperfusion in the eyes of Sprague Dawley rats. This small-molecule drug candidate is able to compensate for experimental global eye ischemia-reperfusion injury elicited by ligation of blood vessels in rats. We successfully demonstrated that BGP is able to exert its protective effects on the retina even if administered in the form of eyedrops.