Frequency modulation of neural oscillations according to visual task demands.

Temporal integration in visual perception is thought to occur within cycles of occipital alpha-band (8-12 Hz) oscillations. Successive stimuli may be integrated when they fall within the same alpha cycle and segregated for different alpha cycles. Consequently, the speed of alpha oscillations correlates with the temporal resolution of perception, such that lower alpha frequencies provide longer time windows for perceptual integration and higher alpha frequencies correspond to faster sampling and segregation. Can the brain's rhythmic activity be dynamically controlled to adjust its processing speed according to different visual task demands? We recorded magnetoencephalography (MEG) while participants switched between task instructions for temporal integration and segregation, holding stimuli and task difficulty constant. We found that the peak frequency of alpha oscillations decreased when visual task demands required temporal integration compared with segregation. Alpha frequency was strategically modulated immediately before and during stimulus processing, suggesting a preparatory top-down source of modulation. Its neural generators were located in occipital and inferotemporal cortex. The frequency modulation was specific to alpha oscillations and did not occur in the delta (1-3 Hz), theta (3-7 Hz), beta (15-30 Hz), or gamma (30-50 Hz) frequency range. These results show that alpha frequency is under top-down control to increase or decrease the temporal resolution of visual perception.

Surface Potential-Controlled Oscillation in FET-Based Biosensors.

Field-effect transistor (FET)-based biosensors have garnered significant attention for their label-free electrical detection of charged biomolecules. Whereas conventional output parameters such as threshold voltage and channel current have been widely used for the detection and quantitation of analytes of interest, they require bulky instruments and specialized readout circuits, which often limit point-of-care testing applications. In this study, we demonstrate a simple conversion method that transforms the surface potential into an oscillating signal as an output of the FET-based biosensor. The oscillation frequency is proposed as a parameter for FET-based biosensors owing to its intrinsic advantages of simple and compact implementation of readout circuits as well as high compatibility with neuromorphic applications. An extended-gate biosensor comprising an Al2O3-deposited sensing electrode and a readout transistor is connected to a ring oscillator that generates surface potential-controlled oscillation for pH sensing. Electrical measurement of the oscillation frequency as a function of pH reveals that the oscillation frequency can be used as a sensitive and reliable output parameter in FET-based biosensors for the detection of chemical and biological species. We confirmed that the oscillation frequency is directly correlated with the threshold voltage. For signal amplification, the effects of circuit parameters on pH sensitivity are investigated using different methods, including electrical measurements, analytical calculations, and circuit simulations. An Arduino board to measure the oscillation frequency is integrated with the proposed sensor to enable portable and real-time pH measurement for point-of-care testing applications.

Experimental study of the effect of internal pressure on oscillating behavior of pool fires.

A series of experiments have been conducted to study the flame behavior of ethanol pool fires in a closed chamber. The effect of internal pressure and the size of the pool burner is considered. Tests include pressure conditions ranging from 50 kPa to 350 kPa and 5 circular pool burners with different diameters (2 cm, 4 cm, 6 cm, 8 cm, and 10 cm). Measurements such as gas temperature, internal pressure, oxygen concentration, and video record for all tests are obtained. Steady-state burning period is identified to facilitate a quantitative analysis of flame behavior. Image processing is carried out to obtain time average appearance of pool fires. The concept of oscillation intensity is introduced. Oscillation behaviors of pool fires in a closed system as a function of internal pressure and pan diameter are correlated with oscillation intensity. Four flame structures are observed: laminar, tip flicking, sinuous meandering, and turbulent flame. Relationships between oscillation intensity to flame structure and Grashof number to flame structure are established. Effect of internal pressure and gravitational force to oscillation frequency is also accessed. Simple theoretical model is developed. An empirical expression using the relationship of Strouhal number and Grashof number is established. Two distinct behaviors on oscillation frequency as a function of pressure are observed. Results obtained from this work will facilitate the understanding of oscillation behavior of ethanol pool fires in different sizes with various internal pressure conditions in a closed chamber.

Influence of the oscillation frequency of different side-to-side toothbrushes on noncontact biofilm removal.

OBJECTIVES: The objective of this study was to investigate the influence of different oscillation frequencies of three powered toothbrushes with side-to-side action for noncontact biofilm removal in an artificial interdental space model. MATERIALS AND METHODS: A three-species biofilm (Porphyromonas gingivalis, Fusobacterium nucleatum and Streptococcus sanguinis) was formed in vitro on protein-coated titanium disks using a flow chamber system combined with a static biofilm growth model. The oscillation frequencies of three commercial side-to-side toothbrushes were evaluated by means of a dose response. The frequency was decreased in steps (100, 85, 70, 55, and 40%). Subsequently, the biofilm-coated substrates were exposed to the side-to-side toothbrushes. The biofilm volumes were measured using volumetric analyses (Imaris 8.1.2) with confocal laser scanning microscope images (Zeiss LSM700). RESULTS: Compared to maximum oscillation frequency (100%), lower oscillation frequencies (up to 40%) resulted in reduced median percentages of biofilm reduction (median biofilm reduction up to 53% for maximum oscillation frequency, and up to 13% for 40% oscillation frequency) (p ≥ 0.03). In addition, decreasing the oscillation frequencies of the side-to-side toothbrushes showed an enhanced variety in the results of repeated experiments. CONCLUSIONS: The oscillation frequency of the tested side-to-side toothbrushes affected the biofilm reduction in an interdental space model. CLINICAL RELEVANCE: Within a toothbrush, higher oscillation frequencies may lead to beneficial effects on interdental biofilm removal by noncontact brushing.

Membrane resonance enables stable and robust gamma oscillations.

Neuronal mechanisms underlying beta/gamma oscillations (20-80 Hz) are not completely understood. Here, we show that in vivo beta/gamma oscillations in the cat visual cortex sometimes exhibit remarkably stable frequency even when inputs fluctuate dramatically. Enhanced frequency stability is associated with stronger oscillations measured in individual units and larger power in the local field potential. Simulations of neuronal circuitry demonstrate that membrane properties of inhibitory interneurons strongly determine the characteristics of emergent oscillations. Exploration of networks containing either integrator or resonator inhibitory interneurons revealed that: (i) Resonance, as opposed to integration, promotes robust oscillations with large power and stable frequency via a mechanism called RING (Resonance INduced Gamma); resonance favors synchronization by reducing phase delays between interneurons and imposes bounds on oscillation cycle duration; (ii) Stability of frequency and robustness of the oscillation also depend on the relative timing of excitatory and inhibitory volleys within the oscillation cycle; (iii) RING can reproduce characteristics of both Pyramidal INterneuron Gamma (PING) and INterneuron Gamma (ING), transcending such classifications; (iv) In RING, robust gamma oscillations are promoted by slow but are impaired by fast inputs. Results suggest that interneuronal membrane resonance can be an important ingredient for generation of robust gamma oscillations having stable frequency.

Quasi-Continuous Wave Pulsed Laser Welding of Copper Lap Joints Using Spatial Beam Oscillation.

Laser beam welding of copper (Cu) using near-infrared radiation is extremely challenging due to its high thermal conductivity and large laser reflectivity. In the present study, the challenges and benefits of using spatial beam oscillation during quasi-continuous wave (QCW) pulsed laser beam welding of 0.4 mm Cu to 1 mm Cu in lap joint configuration are presented. This work demonstrates how laser beam oscillating parameters can be used to control the laser weld quality and laser weld dimensions for Cu-Cu joining. Compared to a non-oscillated laser beam, welds made using laser beam oscillation showed fewer spatters, porosities, and better surface quality. Four levels of oscillating amplitudes (0.2 mm, 0.4 mm, 0.6 mm, and 0.8 mm) and oscillating frequencies (100 Hz, 200 Hz, 300 Hz, and 400 Hz) were compared to reveal the effect of beam oscillation parameters. The weld width was mainly controlled by oscillating amplitude, while weld penetration was affected by both oscillating amplitude and frequency. As the oscillating amplitude increased, the weld width increased while the weld penetration decreased. Increasing the oscillating frequency reduced the weld penetration but had a negligible effect on the weld width. The maximum tensile force of approximately 1944 N was achieved for the joint with a high width-to-depth ratio with an oscillating amplitude of 0.8 mm and an oscillating frequency of 200 Hz.

Spin torque oscillations triggered by in-plane field.

We study the dynamics of a spin torque nano oscillator that consists of parallelly magnetized free and pinned layers by numerically solving the associated Landau-Lifshitz-Gilbert-Slonczewski equation in the presence of a field-like torque. We observe that an in-plane magnetic field which is applied for a short interval of time (<1 ns) triggers the magnetization to exhibit self-oscillations from low energy initial magnetization state. Also, we confirm that the frequency of oscillations can be tuned over the range ∼25-∼72 GHz by current, even in the absence of field-like torque. We find the frequency enhancement up to 10 GHz by the presence of field-like torque. We determine theQ-factor for different frequencies and show that it increases with frequency. Our analysis with thermal noise confirms that the system is stable against thermal noise and the dynamics is not altered appreciably by it.

Electrophysiological signatures of attentional control in bilingual processing: Evidence from proactive interference.

Monolingual and bilingual participants performed a Proactive Interference task in verbal and nonverbal conditions while EEG was recorded. Behavioral results showed faster responses for bilinguals on interference trials in the nonverbal condition, and electrophysiological results indicated greater attentional control for bilinguals. ROI analyses showed this pattern for bilinguals mainly in the verbal condition, whereas whole brain analyses found this association in both conditions. Frequency power analysis found activity related to interference trials was associated with recruitment of different neural resources for verbal and nonverbal conditions. Nonverbal results indicated beta activity for interference trials in bilinguals and the verbal condition showed this pattern in theta and gamma frequency bands as well, revealing more extensive brain activation in the verbal domain for bilinguals. For monolinguals, frequency power in beta, gamma, and theta were related to facilitation trials. These results suggest different strategies for allocating attention by monolingual and bilingual young adults.

The theoretical mechanism of Parkinson's oscillation frequency bands: a computational model study.

Excessive synchronous oscillation activities appear in the brain is a key pathological feature of Parkinson's disease, the mechanism of which is still unclear. Although some previous studies indicated that ß oscillation (13-30 Hz) may directly originate in the network composed of the subthalamic nucleus (STN) and external globus pallidus (GPe) neurons, specific onset mechanisms of which are unclear, especially theoretical evidences in numerical simulation are still little. In this paper, we employ a STN-GPe mean-field model to explore the onset mechanism of Parkinson's oscillation. In addition to ß oscillation, we find that some other common oscillation frequency bands can appear in this network, such as the α oscillation band (8-12 Hz), the θ oscillation band (4-7 Hz) and δ oscillation band (1-3 Hz). In addition to the coupling weight between the STN and GPe, the delay is also a critical factor to affect oscillatory activities, which can not be neglected compared to other parameters. Through simulation and analysis, we propose two possible theories may induce the system to transfer from the stable state to the oscillatory state in this model: (1). The oscillation activity can be induced when the firing activation level of the population increases to large enough; (2). In some special cases, the population may stay in the high firing rate stable state and the mean discharge rate of which is too large to induce oscillations, then oscillation activities may be induced as the MD decreases to moderate value. In most situations, the change trends of the MD and oscillation dominant frequency are contrary, which may be an important physiological phenomenon shown in this model. The delays and firing rates were obtained by simulating, which may be verified in the experiment in the future.

Carbon Nanotube Based Radio Frequency Transistors for K-Band Amplifiers.

Owing to the combination of high carrier mobility and saturation velocity, low intrinsic capacitance, and excellent stability, the carbon nanotube (CNT) has been considered as a perfect semiconductor to construct radio frequency (RF) field-effect transistors (FETs) and circuits with an ultrahigh frequency band. However, the reported CNT RF FETs usually exhibited poor real performance indicated by the as-measured maximum oscillation frequency (fmax), and then the amplifiers, which are the most important and fundamental RF circuits, suffered from a low power gain and a low frequency band. In this work, we build RF transistors on solution-derived randomly orientated CNT films with improved quality and uniformity. The randomly orientated CNT film FETs exhibit the record as-measured maximum fmax of 90 GHz, demonstrating the potential for over 28 GHz (at least one-third of 90 GHz) 5G mmWave (frequency range 2) applications. Benefiting from the large-scale uniformity of CNT films, FETs are designed and fabricated with a large channel width to present low internal resistance for the standard 50 Ω impedance matching guide line, which is critical to construct an RF amplifier. Furthermore, we first demonstrate amplifiers with a maximum power gain up to 11 dB and output third-order intercept point (OIP3) of 15 dBm, both at the K-band, which represents the record of a CNT amplifier and is even comparable with a commercial amplifier based on III-V RF transistors.

Carbon Nanotube Film-Based Radio Frequency Transistors with Maximum Oscillation Frequency above 100 GHz.

Carbon nanotubes (CNTs) have been considered a preferred channel material for constructing high-performance radio frequency (RF) transistors with outstanding current gain cutoff frequency (fT) and power gain cutoff frequency (fmax) but the highest reported fmax is only 70 GHz. Here, we explore how good RF transistors based on solution-derived randomly oriented semiconducting CNT films, which are the most mature CNT materials for scalable fabrication of transistors and integrated circuits, can be achieved. Owing to the significantly reduced number of CNT/CNT junctions obtained by scaling the channel length down to below 100 nm, we realized RF field-effect transistors (FETs) with maximum transconductance Gm up to 0.38 mS/µm, which is the record among CNT-based RF FETs. After de-embedding the pad-induced capacitances and resistances, the CNT FETs with different gate lengths (Lg) exhibit fT as high as 103 GHz (intrinsically 281 GHz) or fmax up to 107 GHz (intrinsically 190 GHz), which are the records among CNT-based RF FETs. In particular, the CNT FETs with an Lg of 50 nm present pad de-embedding fT of 86 GHz and fmax of 85 GHz, and represent the best CNT RF transistor in terms of comprehensive performance to date. To demonstrate the actual high-speed and scalable fabrication of our CNT RF FETs, we fabricated CNT FET-based five-stage ring oscillators with oscillation frequencies above 5 GHz.

Oscillation-specific nodal alterations in early to middle stages Parkinson's disease.

BACKGROUND: Different oscillations of brain networks could carry different dimensions of brain integration. We aimed to investigate oscillation-specific nodal alterations in patients with Parkinson's disease (PD) across early stage to middle stage by using graph theory-based analysis. METHODS: Eighty-eight PD patients including 39 PD patients in the early stage (EPD) and 49 patients in the middle stage (MPD) and 36 controls were recruited in the present study. Graph theory-based network analyses from three oscillation frequencies (slow-5: 0.01-0.027 Hz; slow-4: 0.027-0.073 Hz; slow-3: 0.073-0.198 Hz) were analyzed. Nodal metrics (e.g. nodal degree centrality, betweenness centrality and nodal efficiency) were calculated. RESULTS: Our results showed that (1) a divergent effect of oscillation frequencies on nodal metrics, especially on nodal degree centrality and nodal efficiency, that the anteroventral neocortex and subcortex had high nodal metrics within low oscillation frequencies while the posterolateral neocortex had high values within the relative high oscillation frequency was observed, which visually showed that network was perturbed in PD; (2) PD patients in early stage relatively preserved nodal properties while MPD patients showed widespread abnormalities, which was consistently detected within all three oscillation frequencies; (3) the involvement of basal ganglia could be specifically observed within slow-5 oscillation frequency in MPD patients; (4) logistic regression and receiver operating characteristic curve analyses demonstrated that some of those oscillation-specific nodal alterations had the ability to well discriminate PD patients from controls or MPD from EPD patients at the individual level; (5) occipital disruption within high frequency (slow-3) made a significant influence on motor impairment which was dominated by akinesia and rigidity. CONCLUSIONS: Coupling various oscillations could provide potentially useful information for large-scale network and progressive oscillation-specific nodal alterations were observed in PD patients across early to middle stages.

200 GHz Maximum Oscillation Frequency in CVD Graphene Radio Frequency Transistors.

Graphene is a promising candidate in analog electronics with projected operation frequency well into the terahertz range. In contrast to the intrinsic cutoff frequency (fT) of 427 GHz, the maximum oscillation frequency (fmax) of graphene device still remains at low level, which severely limits its application in radio frequency amplifiers. Here, we develop a novel transfer method for chemical vapor deposition graphene, which can prevent graphene from organic contamination during the fabrication process of the devices. Using a self-aligned gate deposition process, the graphene transistor with 60 nm gate length exhibits a record high fmax of 106 and 200 GHz before and after de-embedding, respectively. This work defines a unique pathway to large-scale fabrication of high-performance graphene transistors, and holds significant potential for future application of graphene-based devices in ultra high frequency circuits.

Propofol-Induced Frontal Cortex Disconnection: A Study of Resting-State Networks, Total Brain Connectivity, and Mean BOLD Signal Oscillation Frequencies.

Propofol is one of the most commonly used anesthetics in the world, but much remains unknown about the mechanisms by which it induces loss of consciousness. In this resting-state functional magnetic resonance imaging study, we examined qualitative and quantitative changes of resting-state networks (RSNs), total brain connectivity, and mean oscillation frequencies of the regional blood oxygenation level-dependent (BOLD) signal, associated with propofol-induced mild sedation and loss of responsiveness in healthy subjects. We found that detectability of RSNs diminished significantly with loss of responsiveness, and total brain connectivity decreased strongly in the frontal cortex, which was associated with increased mean oscillation frequencies of the BOLD signal. Our results suggest a pivotal role of the frontal cortex in propofol-induced loss of responsiveness.

Comparing mouse and human pluripotent stem cell derived cardiac cells: Both systems have advantages for pharmacological and toxicological screening.

Pluripotent stem cells offer an unparalleled opportunity to investigate cardiac physiology, pharmacology, toxicology and pathophysiology. In this paper we describe the use of both mouse (Nkx2-5(eGFP/w)) and human (NKX2-5(eGFP/w)) pluripotent stem cell reporter lines, differentiated toward cardiac lineage, for live single cell high acquisition rate calcium imaging. We also assess the potential of NKX2-5(eGFP/w) cardiac lineage cells for use toxicological screening as well as establish their sensitivity to a shift between low and high oxygen environments. Differentiated mouse Nkx2-5(eGFP/w) cells demonstrated a wide range of spontaneous oscillation rates that could be reduced by ryanodine (10µM), thapsigargin (1µM) and ZD7288 (10µM). In contrast human NKX2-5(eGFP/w) cell activity was only reduced by thapsigargin (1µM). Human cell survival was sensitive to the addition of trastuzumab and doxorubicin, while the switch from a low to a high oxygen environment affected oscillation frequency. We suggest that the human NKX2-5(eGFP/w) cells are less suitable for studies of compounds affecting cardiac pacemaker activity than mouse Nkx2-5(eGFP/w) cells, but are very suitable for cardiac toxicity studies.

Altered modulation of gamma oscillation frequency by speed of visual motion in children with autism spectrum disorders.

BACKGROUND: Recent studies link autism spectrum disorders (ASD) with an altered balance between excitation and inhibition (E/I balance) in cortical networks. The brain oscillations in high gamma-band (50-120 Hz) are sensitive to the E/I balance and may appear useful biomarkers of certain ASD subtypes. The frequency of gamma oscillations is mediated by level of excitation of the fast-spiking inhibitory basket cells recruited by increasing strength of excitatory input. Therefore, the experimental manipulations affecting gamma frequency may throw light on inhibitory networks dysfunction in ASD. METHODS: Here, we used magnetoencephalography (MEG) to investigate modulation of visual gamma oscillation frequency by speed of drifting annular gratings (1.2, 3.6, 6.0 °/s) in 21 boys with ASD and 26 typically developing boys aged 7-15 years. Multitaper method was used for analysis of spectra of gamma power change upon stimulus presentation and permutation test was applied for statistical comparisons. We also assessed in our participants visual orientation discrimination thresholds, which are thought to depend on excitability of inhibitory networks in the visual cortex. RESULTS: Although frequency of the oscillatory gamma response increased with increasing velocity of visual motion in both groups of participants, the velocity effect was reduced in a substantial proportion of children with ASD. The range of velocity-related gamma frequency modulation correlated inversely with the ability to discriminate oblique line orientation in the ASD group, while no such correlation has been observed in the group of typically developing participants. CONCLUSIONS: Our findings suggest that abnormal velocity-related gamma frequency modulation in ASD may constitute a potential biomarker for reduced excitability of fast-spiking inhibitory neurons in a subset of children with ASD.

Influencia de un campo magnético oscilante en columnas poliméricas con nanopartículas magnéticas / Influence of an oscillating magnetic field on polymeric columns with magnetic nanoparticles / Influência de um campo magnético oscilante em colunas poliméricas com nanopartículas magnéticas

Resumen Las nanopartículas magnéticas de magnetita (MNP) presentan comportamiento superparamagnético, lo que les confiere propiedades importantes como bajo campo coercitivo, fácil modificación superficial y niveles de magnetización aceptables. Esto las hace útiles en técnicas de separación. Sin embargo, pocos estudios han experimentado con las interacciones de las MNP con campos magnéticos. Por tanto, el objetivo de esta investigación fue estudiar la influencia de un campo magnético oscilante (CMO) en columnas monolíticas poliméricas con nanopartículas magnéticas vinilizadas (VMNP) para cromatografía líquida capilar (cLC). Para ello, se sintetizaron MNP mediante coprecipitación de sales de hierro. La preparación de las columnas monolíticas poliméricas se realizó por copolimerización y la agregación de VMNP. Aprovechando las propiedades magnéticas de las MNP, se estudió la influencia de los parámetros como frecuencia de resonancia, intensidad y tiempo de exposición de un CMO, aplicado a las columnas sintetizadas. Como resultado se obtuvo una mejor separación de la muestra según los parámetros medidos, de modo que se logró una resolución de la columna (Rs) de 1,35. Las propiedades morfológicas de las columnas fueron evaluadas mediante microscopía electrónica de barrido (SEM). Los resultados de las propiedades cromatográficas revelaron que la mejor separación de la muestra de alquilbencenos se da en condiciones de 5,5 kHz y 10 min de exposición en el CMO. Este estudio constituye una primera aplicación en técnicas de separación cromatográficas para futuras investigaciones en nanotecnología.

Abstract Magnetite magnetic nanoparticles (MNP) exhibit superparamagnetic behavior, which gives them important properties such as low coercive field, easy surface modification and acceptable levels of magnetization, making them useful in separation techniques. However, few studies have experimented the interactions they have with magnetic fields. For this reason, in this research, the influence of an oscillating magnetic field (CMO) on polymeric monolithic columns containing vinylized magnetite magnetic nanoparticles (VMNP) for capillary liquid chromatography was studied. For this, MNP were synthesized, by co-precipitation of iron salts. The preparation of the polymeric monolithic columns was carried out by the copolymerization method and the subsequent aggregation of VMNP. Taking advantage of the magnetic properties of the MNPs, the influence of various parameters (resonance frequency, intensity, and exposure time) of an CMO applied to the synthesized columns was studied. As a result, a better separation of the sample according to the measured parameters was obtained. Thus, achieving a column resolution (Rs) of 1.35. The morphological properties of monolithic columns were evaluated using scanning electron microscopy (SEM). The results of the chromatographic properties showed that the best separation of the sample of alkylbenzenes (ABS) in cLC occurs under conditions of 5.5 kHz and 10 min of exposure in the CMO. This study constitutes the first application in chromatographic separation techniques for future nanotechnology research.

Resumo As nanopartículas de magnetita magnética (MNPs) têm comportamento superparamagnético, o que lhes confere propriedades importantes como baixo campo coercitivo, fácil modificação da superfície e níveis aceitáveis de magnetização, tornando os úteis nas técnicas de separação. No entanto, poucos estudos foram realizados experimentando as interações exercidas pelos campos magnéticos. Portanto, o objetivo da presente investigação foi estudar a influência de um campo magnético oscilante (CMO) em colunas monolíticas poliméricas contendo nanopartículas magnéticas vinilizadas (VMNPs) para cromatografia líquida capilar (cLC). Para isso, MNPs foram sintetizados por co-precipitação de sais de ferro. A preparação das colunas monolíticas poliméricas foi realizada por copolimerização e subsequente agregação de VMNPs. Em seguida, aproveitando as propriedades magnéticas do MNPs, estudou-se a influência de vários parâmetros (frequência de ressonância, intensidade e tempo de exposição) de uma CMO aplicada nas colunas sintetizadas, obtendo vantagens como uma melhor separação da amostra e uma resolução (Rs) de coluna de 1,35. As propriedades morfológicas das colunas monolíticas foram avaliadas por microscopia eletrônica de varredura (SEM). Os resultados das propriedades cromatográficas mostraram que a melhor separação da amostra de alquilbenzenos (ABS) em cLC ocorre em condições de 5,5 kHz e 10 min de exposição na CMO. Este estudo constitui uma primeira aplicação em técnicas de separação cromatográfica para futuras investigações em nanotecnologia.

Capacitance effect on the oscillation and switching characteristics of spin torque oscillators.

We have studied the capacitance effect on the oscillation characteristics and the switching characteristics of the spin torque oscillators (STOs). We found that when the external field is applied, the STO oscillation frequency exhibits various dependences on the capacitance for injected current ranging from 8 to 20 mA. The switching characteristic is featured with the emerging of the canted region; the canted region increases with the capacitance. When the external field is absent, the STO free-layer switching time exhibits different dependences on the capacitance for different injected current. These results help to establish the foundation for capacitance-involved STO modeling.