Short Time Delay Research Articles

Perceived patient safety culture and its associated factors among clinical managers of tertiary hospitals: a cross-sectional survey

BackgroundPatient safety is a global challenge influenced by perceived patient safety culture. However, limited knowledge exists regarding the patient safety culture perceived by hospital clinical managers and its associated factors. This study aims to investigate the perceptions of patient safety culture and associated factors among clinical managers of tertiary hospitals in China.MethodsA cross-sectional survey was conducted from June 19 to July 16, 2021, involving 539 clinical managers from four tertiary hospitals in Changsha City of Hunan Province. The Hospital Survey on Patient Safety Culture (HSOPSC) was utilized to assess perceived patient safety culture. Bivariate, multivariable linear regression, and logistic regression analyses were performed.ResultsThe mean score for the total HSOPSC was 72.5 ± 7.6, with dimensional scores ranging from 62.1 (14.9) to 86.6 (11.7). Three dimensions exhibited positive response rates (PRRs) < 50%, indicating areas that need to be improved: “nonpunitive response to errors” (40.5%), “staffing” (41.9%), and “frequency of events reported” (47.4%). Specialized hospitals (β = 1.744, P = 0.037), female gender (β = 2.496, P = 0.003), higher professional title (β = 1.413, P = 0.049), a higher education level (β = 1.316, P = 0.001), and shorter time delays per shift (β=-1.13, P < 0.001) were correlated with higher perceived patient safety culture. Education level, work department, “teamwork within a unit”, “management support for patient safety”, “communication openness”, and “staffing” dimensions were associated with patient safety grades (all P < 0.05). Years worked in hospitals, occupation, education level, work department, hospital nature, professional title, “communication openness”, and “handoffs & transitions” were associated with the number of adverse events reported (all P < 0.05).ConclusionsOur study revealed a generally low level of patient safety culture perceived by clinical managers and identified priority areas requiring urgent improvement. The associated factors of patient safety culture provide important guidance for the development of targeted interventions in the future. Promoting patient safety by optimizing the patient safety culture perceived by clinical managers should be prioritized.

Effect of pulse configuration on the reactive deposition of TiN coatings using HiPIMS

In this work, TiN coatings are deposited using three different series of pulse configurations. Each series consisted of a single pulse of 90 μs, chopped into 2-, 3-, and 6-pulse sequences, where the short delay time between the sequential chopped pulses have been varied from 10 to 300 μs. This allows control of the intensity of the target peak current, which in turn affects the deposition rate and mechanical properties of the growing coatings. Results show that changing the pulse configuration resulted in a deposition rate comprised between 4.4 and 5.2 μm/h. The change observed in deposition rate can be attributed to several phenomena known to reduce the deposition rate. This includes gas rarefaction, self-sputtering, target poisoning, and power loss resulting from the increase in circuit impedance when power is switched on and off during the pulsing process. It was shown that strategic selection of the pulse configuration plays a crucial role in mitigating the negative impact of these phenomena which opens up favorable conditions for a substantial enhancement in the deposition rate. In fact, the proper choice of pulse configuration can result in an enhanced deposition rate of up to 12.3 % compared to the conventional single pulse case. An overall slight increase in the average hardness from 18.7 GPa to 19.8 and 22 GPa for the 2-, 3-, and 6-pulse series respectively, while no noticeable structural changes were observed.

Decentralized piggybacking-based dissemination of Cooperative Awareness Messages in vehicular ad-hoc networks

Vehicle-to-Vehicle (V2V) communication has shown great promise to improve road safety and traffic efficiency via the periodic broadcasting of Cooperative Awareness Messages (CAMs), in which traffic information could be exchanged among adjacent vehicles. Since each CAM contains local-observed traffic information such as geolocation, speed, and safety alerts, frequent CAM losses will decrease the reliability on avoiding crashes and injuries on the road. Existing solutions tend to recover the lost CAMs through either source-based re-transmission or neighbor-based forwarding, which may suffer from significant performance degradation due to the fast movement of vehicles and high dynamic network topology. In this paper, we develop a decentralized cooperative broadcasting protocol for CAM dissemination, where each vehicle can piggyback some received CAMs in its routine broadcasting to help others recover their lost CAMs. To promote cooperation of CAM piggybacking, a new data structure called bitmap is introduced to record the packet receiving status at each vehicle, based on which time slots could be allocated to vehicles with low data collisions, lost CAMs could be detected only using each vehicle’s local information, and the qualities of wireless links could be estimated dynamically. Then, we propose two piggybacking schemes, Benefit-based Piggybacking (BP) and Suggestion-based Piggybacking (SP), aiming to maximize the average CAM delivery ratio. We evaluate the proposed schemes in simulations with realistic vehicle mobility traces and channel models. Simulation results show that our bitmap-based lost CAM detection has superior performance than traditional request-based solutions. In comparison with forwarding-based schemes, our schemes can achieve much higher CAM broadcast reliability with short time delay and small communication overhead.

Frequency spectrum characteristics of blast-induced vibration with electronic detonators in ground blasting

With the wide application of electronic detonators in blasting engineering, further study of frequency spectrum characteristics under precise delay time is essential for blasting design and safety evaluation. In this paper, the frequency spectra induced by blasting vibration under different delay times and distances are calculated, the frequency distribution and energy characteristics of various frequency bands are then investigated, and the demonstration is conducted using numerical simulation and electronic detonator blasting experiments. The results show that the low-frequency vibration proportion increases, and the dominant frequency shifts to a lower frequency compared with the vibration frequency distribution of single-hole blasting when using a very short delay time (≤5 ms). However, when a short delay time (6–12 ms) is used, the low-frequency shift to high frequency, reducing the energy ratio of low-frequency bands. And there are certain differences in the delay time to reduce PPV at different blasting center distances. A shorter delay time (6–8 ms) in the nearer region and a longer delay time (10–20 ms) in the intermediate and farther regions better reduce blasting vibration. Finally, considering multiple influencing factors, the 7–12 ms delay time is recommended to protect structures in the blasting area factors.

Age-related differences in temporal binding and the influence of action body parts.

If voluntary action is followed by an effect with a short time delay, the time interval between action and effect is often perceived to be shorter than it actually is. This perceptual time compression is termed intentional binding or temporal binding. We investigated age-related changes in adulthood considering temporal binding and its dependence on action body parts (i.e., hand vs. foot). This experiment included 17 young adults (mean age: 21.71 ± 3.14 years) and 27 older adults (mean age: 74.41 ± 3.38 years). Participants performed a button press task using their index fingers (hand condition) or toes (foot condition). The results showed that older participants exhibited a strong time compression comparable to young participants in the voluntary condition. Older participants also showed a strong time compression in involuntary action, which was induced by a mechanical device, differently from young participants. In line with previous research, the present age-related differences in time compression considering involuntary action suggest that causal belief significantly influences event perception rather than the associated intention of action or sensory afferents. The present results also suggest that the nature of action body parts has no significant influence on temporal binding, independent of age group.

Estimates of energy fluxes associated with sprites in the mesosphere

We present calibrated estimates of photon flux, lightning peak Poynting flux and Joule heating associated with the brightest region of sprites observed in the mesosphere over South Africa. The sprites' photon fluxes were estimated using 28 sprites events (observed during the 2019 sprites campaign) calibrated by stars in the sprite's image background. The lightning driven background electric field associated with the brightest region of sprites were found to vary from 0.1 to 6.7 Ek (local air breakdown field). The lightning return stroke at lower frequencies (4 Hz - 2 kHz) has more influence in carrot sprites than in column sprites formation processes. The lightning peak Poynting flux and Joule heating were estimated from calibrated electromagnetic field measurements made in parallel with eight sprites events (observed during the 2020 sprites campaign). The photon flux, peak Poynting flux, and peak Joule heating associated with the brightest region of sprites were found to be 1.1 × 10−7 W/m2, 12.7 W/m2, and 4.7 × 10−3 W/m2 on average, respectively. The altitude/distance-normalised lightning peak Poynting flux decreases with increasing atmospheric altitude. The photon flux from column sprites decreased with increased altitude of the brightest region. Column sprites have a shorter time delay (<30 ms) from their parent lightning strokes than carrot sprites (up to 145 ms).

Observational constraints on the origin of the elements – VI. Origin and evolution of neutron-capture elements as probed by the Gaia-ESO survey

ABSTRACT Most heavy elements beyond the iron peak are synthesized via neutron capture processes. The nature of the astrophysical sites of neutron capture processes is still very unclear. In this work, we explore the observational constraints of the chemical abundances of s-process and r-process elements on the sites of neutron-capture processes by applying Galactic chemical evolution (GCE) models to the data from Gaia-ESO large spectroscopic stellar survey. For the r-process, the [Eu/Fe]–[Fe/H] distribution suggests a short delay time of the site that produces Eu. Other independent observations (e.g. NS–NS binaries), however, suggest a significant fraction of long delayed (&amp;gt;1 Gyr) neutron star mergers (NSM). When assuming NSM as the only r-process sites, these two observational constraints are inconsistent at above 1σ level. Including short delayed r-process sites like magnetorotational supernova can resolve this inconsistency. For the s-process, we find a weak metallicity dependence of the [Ba/Y] ratio, which traces the s-process efficiency. Our GCE model with up-to-date yields of AGB stars qualitatively reproduces this metallicity dependence, but the model predicts a much higher [Ba/Y] ratio compared to the data. This mismatch suggests that the s-process efficiency of low-mass AGB stars in the current AGB nucleosynthesis models could be overestimated.

Seismic anisotropy indicates organized melt beneath the Mid-Atlantic Ridge aids seafloor spreading

Abstract Lithospheric plates diverge at mid-ocean ridges and asthenospheric mantle material rises in response. The rising material decompresses, which can result in partial melting, potentially impacting the driving forces of the system. Yet the geometry and spatial distribution of the melt as it migrates to the ridge axis are debated. Organized melt fabrics can cause strong seismic anisotropy, which can be diagnostic of melt, although this is typically not found at ridges. We present anisotropic constraints from an array of 39 ocean-bottom seismometers deployed on 0–80 Ma lithosphere from March 2016 to March 2017 near the equatorial Mid-Atlantic Ridge (MAR). Local and SKS measurements show anisotropic fast directions away from the ridge axis, which are consistent with strain and associated fabric caused by plate motions with short delay times, δt (&amp;lt;1.1 s). Near the ridge axis, we find several ridge-parallel fast splitting directions, φ, with SKS δt that are much longer (1.7–3.8 s). This is best explained by ridge-parallel sub-vertical orientations of sheet-like melt pockets. This observation is much different than anisotropic patterns observed at other ridges, which typically reflect fabric related to plate motions. One possibility is that thicker sub-ridge lithosphere with steep sub-ridge topography beneath slower spreading centers focuses melt into vertical, ridge-parallel melt bands, which effectively weakens the plate. Associated buoyancy forces elevate the sub-ridge plate, providing greater potential energy and enhancing the driving forces of the plates.

Acetylacetone Photolysis at 280 nm Studied by Velocity-Map Ion Imaging.

The photolysis of acetylacetone (AcAc) has been studied using velocity-map ion imaging with pulsed nanosecond lasers. The enolone tautomer of AcAc (CH3C(O)CH═C(OH)CH3) was excited in the strong UV absorption band by UV pulses at 280 nm, preparing the S2(ππ*) state, and products were probed after a short time delay by single-photon VUV ionization at 118.2 nm. Two-color UV + VUV time-of-flight mass spectra show enhancement of fragments at m/z = 15, 42, 43, 58, and 85 at the lowest UV pulse energies and depletion of the parent ion at m/z = 100. Ion images of the five major fragments are all isotropic, indicating dissociation lifetimes that are long on the timescale of molecular rotation but shorter than the laser pulse duration (<6 ns). The m/z = 15 and 85 fragments have identical momentum distributions with moderate translational energy release, suggesting that they are formed as a neutral product pair and likely via a Norrish type I dissociation of the enolone to form CH3 + C(O)CH═C(OH)CH3 over a barrier on a triplet surface. The m/z = 43 fragment may be tentatively assigned to the alternative Norrish type I pathway that produces CH3CO + CH2C(O)CH3 on S0 following phototautomerization to the diketone, although alternative mechanisms involving dissociative ionization of a larger primary photoproduct cannot be conclusively ruled out. The m/z = 42 and 58 fragments are not momentum-matched and consequently are not formed as a neutral pair via a unimolecular dissociation pathway on S0. They also likely originate from the dissociative ionization of primary photofragments. RRKM calculations suggest that unimolecular dissociation pathways that lead to molecular products on S0 are generally slow, implying an upper-limit lifetime of <46 ns after excitation at 280 nm. Time-dependent measurements suggest that the observed photofragments likely do not arise from dissociative ionization of energized AcAc S0*.

Tunable, coherent optical comb source via on-chip bidirectional coupling.

A tunable comb source is demonstrated through gain switching on a three-sectioned photonic integrated circuit (PIC). The PIC consists of two mutually coupled lasers connected by a passive waveguide. One of these is a tunable, two-section, single mode laser. The second laser is a simple Fabry-Perot cavity laser which can be phase-locked with the single mode laser via bidirectional coupling. Frequency combs are produced by gain switching the Fabry-Perot laser by applying a high-power radio frequency signal. Combs are generated with line spacings ranging from 3.5 to 8 GHz. The on-chip bidirectional coupling causes the comb to also be generated in the two-section device. Despite the lack of on-chip optical isolation between the lasers, the resulting combs are stable. Numerical simulations using a delay-differential model reproduce the results and reveal the important role played by the short delay times inherent to on-chip integration in this stability.

Temporal Evolution and Fluence Dependence of Band Structure in Photoexcited Ta2Ni0.9Co0.1Se5 Probed by Time- and Angle-Resolved Photoemission Spectroscopy

We have investigated the temporal evolution and fluence dependence of band structure in Ta2Ni0.9Co0.1Se5 by means of time- and angle-resolved photoemission spectroscopy (tr-ARPES). With the fluence of 3.00 mJ cm−2 and the delay time of 170 fs, the conduction band crossing the Fermi level (EF) and the valence band reaching EF are observed indicating the photoinduced semimetal phase. However, at the delay time of 70 fs, the valence band top does not reach EF creating a partial gap or a pseudogap, and the transition from the excitonic insulator state to the semimetal state is not completed. The conduction band crossing EF is observed even with the shorter delay time (down to 50–70 fs) and/or the lower fluence (down to 0.32 mJ cm−2). On the other hand, the valence band top stays well below EF up to the fluence of 1.39 mJ cm−2 even at the delay time of 160–170 fs. The different optical responses of the valence and conduction bands suggest a vital role of the lattice fluctuations pointed out by Nakano et al. [Phys. Rev. B 98, 045139 (2018)] on the residual pseudogap at 70 fs after the photoexcitation.

Binary black holes population and cosmology in new lights: signature of PISN mass and formation channel in GWTC-3

ABSTRACT The mass, spin, and merger rate distribution of the binary black holes (BBHs) across cosmic redshifts provide a unique way to shed light on their formation channel. Along with the redshift dependence of the BBH merger rate, the mass distribution of BBHs can also exhibit redshift dependence due to different formation channels and dependence on the metallicity of the parent stars. We explore the redshift dependence of the BBH mass distribution jointly with the merger rate evolution from the third gravitational wave (GW) catalogue GWTC-3 of the LIGO–Virgo–KAGRA collaboration. We study possible connections between peak-like features in the mass spectrum of BBHs and processes related to supernovae physics and time delay distributions. We obtain a preference for short-time delays between star formation and BBH mergers. Using a power-law form for the time delay distribution ($(t^{\rm min}_d)^{d}$), we find d &amp;lt; −0.7 credible at 90 per cent interval. The mass distribution of the BBHs could be fitted with a power-law form with a redshift-dependent peak feature that can be linked to the pair instability supernovae (PISN) mass-scale MPISN(Z*) at a stellar metallicity Z*. For a fiducial value of the stellar metallicity Z* = 10−4, we find the $\rm M_{\rm PISN}(Z_*)=44.4^{+7.9}_{-6.3}$$\rm M_\odot$. This is in accordance with the theoretical prediction of the lower edge of the PISN mass-scale and differs from previous analyses. Although we find a strong dependence of the PISN value on metallicity, the model that we explored is not strongly favoured over those that do not account for metallicity as the Bayes factors are inconclusive. In the future with more data, evidence towards metallicity dependence of the PISN will have a significant impact on our understanding of stellar physics.

Memory window enhancement in n-type ferroelectric field-effect transistors by engineering ozone exposure in atomic layer deposition of HfZrOx films

We demonstrate n-type ferroelectric field-effect transistors (FeFETs) employing atomic-layer-deposited HfZrOx (HZO) films with a large memory window (MW) immediately after the write operation. Charge trapping at the HZO/Si interface in FeFETs is the primary source of memory window reduction. To control the properties of the interfacial layer, we varied the O3 injection time during atomic layer deposition. The HZO (long O3 of 7 s)-based FeFET demonstrated a large MW (2.1 V) in the DC transfer curves compared with the HZO (short O3 of 0.3 s)-based FeFET (0.9 V), although the bulk properties of the HZO films barely changed with the O3 injection time. In pulsed I–V measurements with an extremely short delay time of 100 ns between pulses, the HZO (long O3 of 7 s)-based FeFET showed a large MW of 1.0 V. Such improvements in the performance of HZO-based FeFETs indicate that the trap density in the interfacial layer is reduced by the use of a long O3 injection time. This is supported by the variation in the silicate/SiO2 ratio within the interfacial layer of the HZO films deposited at various O3 injection times.

Real-Time sEMG Pattern Recognition of Multiple-Mode Movements for Artificial Limbs Based on CNN-RNN Algorithm

Currently, sEMG-based pattern recognition is a crucial and promising control method for prosthetic limbs. A 1D convolutional recurrent neural network classification model for recognizing online finger and wrist movements in real time was proposed to address the issue that the classification recognition rate and time delay cannot be considered simultaneously. This model could effectively combine the advantages of the convolutional neural network and recurrent neural network. Offline experiments were used to verify the recognition performance of 20 movements, and a comparative analysis was conducted with CNN and LSTM classification models. Online experiments via the self-developed sEMG signal pattern recognition system were established to examine real-time recognition performance and time delay. Experiment results demonstrated that the average recognition accuracy of the 1D-CNN-RNN classification model achieved 98.96% in offline recognition, which is significantly higher than that of the CNN and LSTM (85.43% and 96.88%, respectively, p &lt; 0.01). In the online experiments, the average accuracy of the real-time recognition of the 1D-CNN-RNN reaches 91% ± 5%, and the average delay reaches 153 ms. The proposed 1D-CNN-RNN classification model illustrates higher performances in real-time recognition accuracy and shorter time delay with no obvious sense of delay in the human body, which is expected to be an efficient control for dexterous prostheses.

H∞ cruise control for high-speed trains with process and data transmission time-varying delay

This paper investigates an H∞ cruise control strategy for uncertain high-speed trains (HSTs) with two time-varying delays. The multibody model of the cascading car is established, taking into account the influence of the flexible coupler and the basic resistance (rolling mechanical resistance + aerodynamic resistance) in the actual operation process. There are many uncertainties in the actual operation of the train, such as disturbances caused by gusts and track irregularities and time-varying delays caused by flexible couplers. Based on the above factors, this paper fully considers and supplements the multibody model. A cruise control strategy based on Lyapunov stability theory and linear matrix inequality (LMI) is proposed. The state feedback control rate with input short time delay is designed, and a cruise control method with double time-varying delays is proposed by sampling data. Constructed Lyapunov–Krasovskii function (LKF) with time-delay parameters for time-delay systems to fully introduce the information of time delays. In view of the disturbance effect, the sufficient condition to suppress the disturbance is given. The proposed H∞ cruise control method controls the fluctuating speed and displacement of the train to quickly converge to the steady state. The HST at equilibrium tracks the desired velocity and ensures a stable relative displacement. The specified H∞ interference attenuation level is achieved to ensure safe and comfortable operation. Two numerical simulations are carried out to illustrate the effect of state time-varying delay and disturbance on train stationarity, which proves the superiority of the proposed method.

Long-lasting XUV activation of helium nanodroplets for avalanche ionization

We study the dynamics of avalanche ionization of pure helium nanodroplets activated by a weak extreme-ultraviolet (XUV) pulse and driven by an intense near-infrared (NIR) pulse. In addition to a transient enhancement of ignition of a nanoplasma at short delay times fs, long-term activation of the nanodroplets lasting up to a few nanoseconds is observed. Molecular dynamics simulations suggest that the short-term activation is caused by the injection of seed electrons into the droplets by XUV photoemission. Long-term activation appears due to electrons remaining loosely bound to photoions which form stable ‘snowball’ structures in the droplets. Thus, we show that XUV irradiation can induce long-lasting changes of the strong-field optical properties of nanoparticles, potentially opening new routes to controlling avalanche-ionization phenomena in nanostructures and condensed-phase systems.

An electro-optic comparator based on photonic crystal ring resonators covered by graphene nanoshells

A logic comparator is a digital circuit comprised of numerous transistors on an integrated circuit that compares two binary numbers. Researchers have proposed various designs for implementing comparators using logic gates, but most are based on DC electrical signals, which suffer from slow switching speeds and high power consumption. This paper presents a novel design for a fast and tunable electro-optic single-bit comparator utilizing graphene-coated nanoshells (GNSs) in photonic crystal (PhC) ring resonators. The comparator's structure includes three inputs, three GNS-coated ring resonators, several waveguides for comparison, and three outputs created in a PhC microstructure in an area of 760 µm². A continuous-wave laser source centered at 1550 nm is applied to the first input to enable the proposed photonic chip. Two other inputs are utilized to apply electrical voltages, and the comparator's task is to compare them. The optical signal applied to the enable input port is directed to the corresponding output depending on the comparison result. We used the finite-difference time-domain method to study the light propagation inside the proposed structure to solve Maxwell's equations. Numerical simulations demonstrate that the designed structure has a very short delay time of 1.85 ps, faster than previously reported comparators, including electronic, optoelectronic, and all-optical comparators. The proposed comparator's rapid response, small area, and tunability make it an appropriate device for optical applications in photonic integrated circuits.

Global Variations in the Time Delays Between Polar Ionospheric Heating and the Neutral Density Response

AbstractWe present results from a study of the time lags between changes in the energy flow into the polar regions and the response of the thermosphere to the heating. Measurements of the neutral density from the Challenging Mini‐satellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) missions are used, along with calculations of the total Poynting flux entering the poles. During two major geomagnetic storms in 2003, these data show increased densities are first seen on the dayside edge of the auroral ovals after a surge in the energy input. At lower latitudes, the densities reach their peak values on the dayside earlier than on the night side. A puzzling response seen in the CHAMP measurements during the November 2003 storm was that the density at a fixed location near the “Harang discontinuity” remained at unusually low levels during three sequential orbit passes, while elsewhere the density increased. The entire database of measurements from the CHAMP and GRACE missions were used to derive maps of the density time lags across the globe. The maps show a large gradient between short and long time delays between 60° and 30° geographic latitude. They confirm the findings from the two storm periods, that near the equator, the density on the dayside responds earlier than on the nightside. The time lags are longest near 18–20 hr local time. The time lag maps could be applied to improve the accuracy of empirical thermosphere models, and developers of numerical models may find these results useful for comparisons with their calculations.

Optimal Timing of Targeted Temperature Management for Post-Cardiac Arrest Syndrome: Is Sooner Better?

Targeted temperature management (TTM) is often considered to improve post-cardiac arrest patients' outcomes. However, the optimal timing to initiate cooling remained uncertain. This retrospective analysis enrolled all non-traumatic post-cardiac arrest adult patients with either out-of-hospital cardiac arrest (OHCA) or in-hospital cardiac arrest (IHCA) who received TTM from July 2015 to July 2021 at our hospital. The values of time delay before TTM and time to target temperature were divided into three periods according to optimal cut-off values identified using receiver operating characteristic curve analysis. A total of 177 patients were enrolled. A shorter time delay before TTM (pre-induction time) was associated with a lower survival chance at 28 days (32.00% vs. 54.00%, p = 0.0279). Patients with a longer cooling induction time (>440 minis) had better neurological outcomes (1.58% vs. 1.05%; p = 0.001) and survival at 28 days (58.06% vs. 29.25%; p = 0.006). After COX regression analysis, the influence of pre-induction time on survival became insignificant, but patients who cooled slowest still had a better chance of survival at 28 days. In conclusion, a shorter delay before TTM was not associated with better clinical outcomes. However, patients who took longer to reach the target temperature had better hospital survival and neurological outcomes than those who were cooled more rapidly. A further prospective study was warranted to evaluate the appropriate time window of TTM.

Колебания геомагнитного поля в диапазоне 2.5–12 Гц в F-слое ионосферы по данным спутников SWARM

We have analyzed geomagnetic variations in the 2.5–12 Hz frequency range in the ionospheric F layer above the electron density maximum, using data from two SWARM satellites. The analysis is based on the data obtained under weak and moderate magnetic activity for 12 days in September and December 2016. To separate spatial inhomogeneities from time variations of the magnetic field, we analyzed signal waveforms and cross-spectra in a 2.56 s sliding window. A maximum in the occurrence and power spectral density of the variations was found at latitudes above the polar boundary of the auroral oval, which correspond to the magnetospheric input layers and dayside polar cusp/cleft. Typical waveforms of the high-latitude variations are the wave packets lasting for 5–10 periods, recorded with a short time delay by two satellites spaced by 40–100 km. These variations might be the ionospheric manifestation of the electromagnetic ion-cyclotron waves generated at the non-equatorial magnetosphere near the polar cusp. The waveforms and cross-spectra of the variations are examined in more details for two cases with different spatial distributions of the magnetic field in the ionosphere. For the ionospheric conditions corresponding to event 1 (September 17, 80° geomagnetic latitude, afternoon sector), spatial distributions of wave magnetic field in the ionosphere and on Earth are estimated using a model of Alfvén beam with a finite radius incident on the ionosphere [Fedorov et al., 2018].