Making use of the recently derived, all-spin, opposite-helicity Compton amplitude, we calculate the classical gravitational scattering amplitude for one spinning and one spinless object at O(G2) and ...all orders in spin. By construction, this amplitude exhibits the spin structure that has been conjectured to describe Kerr black holes. This spin structure alone is not enough to fix all deformations of the Compton amplitude by contact terms, but when combined with considerations of the ultrarelativistic limit we can uniquely assign values to the parameters remaining in the even-in-spin sector. Once these parameters are determined, much of the spin dependence of the amplitude resums into hypergeometric functions. Finally, we derive the eikonal phase for aligned-angular-momentum scattering.
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Cross-frequency coupling (CFC), an electrophysiologically derived measure of oscillatory coupling in the brain, is believed to play a critical role in neuronal computation, learning and ...communication. It has received much recent attention in the study of both health and disease. We searched for literature that studied CFC during resting state and task-related activities during electroencephalography and magnetoencephalography in psychiatric disorders. Thirty-eight studies were identified, which included attention-deficit hyperactivity disorder, Alzheimer’s dementia, autism spectrum disorder, bipolar disorder, depression, obsessive compulsive disorder, social anxiety disorder and schizophrenia. The systematic review was registered with PROSPERO (ID#CRD42021224188). The current review indicates measurable differences exist between CFC in disease states vs. healthy controls. There was variance in CFC at different regions of the brain within the same psychiatric disorders, perhaps this could be explained by the mechanisms and functionality of CFC. There was heterogeneity in methodologies used, which may lead to spurious CFC analyses. Going forward, standardized methodologies need to be established and utilized in further research to understand the neuropathophysiology associated with psychiatric disorders.
•Cross-frequency Coupling (CFC) in the brain plays a critical role in neural computation, learning and communication.•We identified relationships between CFC findings and clinical characteristics, cognition and treatment outcomes.•There is significant measurable differences between CFC in disease states vs. healthy controls.•A significant heterogeneity in methodology used was noticed.•Going forward, standardized methodologies need to be established.
A transmission system with adjustable data rate for single-carrier coherent optical transmission is proposed, which enables high-speed transmission close to the Shannon limit. The proposed system is ...based on probabilistically shaped 64-QAM modulation formats. Adjustable shaping is combined with a fixed-QAM modulation and a fixed forward-error correction code to realize a system with adjustable net data rate that can operate over a large reach range. At the transmitter, an adjustable distribution matcher performs the shaping. At the receiver, an inverse distribution matcher is used. Probabilistic shaping is implemented into a coherent optical transmission system for 64-QAM at 32 Gbaud to realize adjustable operation modes for net data rates ranging from 200 to 300 Gb/s. It is experimentally demonstrated that the optical transmission of probabilistically shaped 64-QAM signals outperforms the transmission reach of regular 16-QAM and regular 64-QAM signals by more than 40% in the transmission reach.
A wideband amplitude to phase (AM-PM) compensated class-AB power amplifier (PA) suitable for highly integrated fifth-generation phased arrays is designed in 0.9-V 28-nm CMOS without RF ultra-thick ...top metal. Design techniques to realize broadband impedance transformation, power division/combining, and phase distortion linearization are discussed. Further, second-order effects due to practical layout constrains imposed by deep-scaled technologies are addressed and simple design solutions are proposed. The designed PA shows a measured <inline-formula> <tex-math notation="LaTeX">S_{21} -3 </tex-math></inline-formula> dB bandwidth (BW) from 29 to 57 GHz (65%) with <inline-formula> <tex-math notation="LaTeX">|\text {AM}-\text {PM}|<1 {^{\circ }} </tex-math></inline-formula> up to <inline-formula> <tex-math notation="LaTeX">P_{1~\text {dB}} </tex-math></inline-formula>. The measured <inline-formula> <tex-math notation="LaTeX">P_{\mathrm{ sat}} </tex-math></inline-formula> is 15.1 dBm over >56% <inline-formula> <tex-math notation="LaTeX">\text {BW}_{-1~\text {dB}} </tex-math></inline-formula>, with a peak power added efficiency of 24.2%. When a signal with wide modulation BW is applied, the realized PA enables up to 10.1-, 8.9-, and 5.9-dBm average <inline-formula> <tex-math notation="LaTeX">P_{\mathrm{ OUT}} </tex-math></inline-formula> while amplifying a 1.5-, 3-, and 6-Gb/s 64-quadratic-amplitude modulation, respectively, at 34 GHz. The in-band and out-of-band linearity measured in error vector magnitude and adjacent channel power ratio are always better than −25 dB and −30 dBc, respectively, without any digital pre-distortion.
▶ The shot peened specimens exhibit longer lifetime compared to unpeened ones as long as the residual stresses introduced by shot peening are reasonably stable. ▶ The stability of residual stresses ...is determined by the plastic strain amplitude and number of cycles during the fatigue loading. ▶ There is a linear equation correlating the residual stresses and the FWHM of the X-ray peak at any depth and total strain amplitude. ▶ Despite the relaxation of residual stresses which starts by start of plastic deformation, much longer lifetimes could be achieved for shot peened specimens provided that the amount and rate of relaxation are limited.
Mechanical surface treatment methods such as shot peening may improve the fatigue strength of materials. In this study, the effect of shot peening on strain controlled constant amplitude fatigue loading of a near pearlitic microalloyed steel was investigated. The stress amplitudes throughout the whole lifetime were followed, in addition to detailed recording of stress–strain hysteresis loops, particularly at small cycle numbers. The detailed relaxation of residual stresses and the changes in full width of half maximum (FWHM) of the X-ray peak at the surface and in depth as function of the number of cycles and plastic strain were recorded. By these techniques, the onset as well as the rate of relaxation of residual stresses could be followed at different strain amplitudes. Pronounced increase in lifetime of the shot peened specimens tested at total strain amplitude smaller than 0.3% (corresponding to 0.034% plastic strain amplitude) was achieved. This coincides with reasonably stable residual stresses at the surface and in depth.
A pseudo-differential distributed power amplifier (DPA) based on complementary gain stages is presented for wideband femtocell 5G indoor communications in 22-nm fully depleted silicon-on-insulator ...(FD-SOI) technology. Capacitive equalization is used to achieve flat bandwidth over the desired frequency range. Due to the complementary gain stages, no expensive bias-Ts are required. In order to improve reverse isolation and increase the output power, stacking is utilized. The design uses back-biasing to set the drain voltages of the DPA instead of the sensitive gate biases. The differences in the design process between a distributed amplifier (DA) and a DPA are presented. Tradeoffs between gain-bandwidth (GBW), reliability, peak power-added efficiency (PAE), output power, and amplitude-to-phase (AMPM) linearity are explored. The DPA achieves an 11.6-dB gain, a 0.4-31.6 GHz 3-dB small-signal bandwidth, and a 16.4 dBm peak-saturated output power (<inline-formula> <tex-math notation="LaTeX">P_{\text {SAT}} </tex-math></inline-formula>) with a 17.2% PAE from the 2.5-V supply. AMPM distortion at output-referred 1-dB compression point (OP 1 dB) and at <inline-formula> <tex-math notation="LaTeX">P_{\text {SAT}} </tex-math></inline-formula> is less than 2°/5° up to the 31 GHz, respectively. It achieves 10 dBm average output power reaching 80/96 gigabit per second (Gbit/s) at 17 GHz with 16/64 QAM modulation. At 28 GHz, it achieves 6.4/4.5 dBm output power with 12/8-Gbit/s data rate with 64/256 QAM modulation.
Electron resonant interaction with whistler mode waves is traditionally considered as one of the main drivers of radiation belt dynamics. The two main theoretical concepts available for its ...description are quasi‐linear theory of electron scattering by low‐amplitude waves and nonlinear theory of electron resonant trapping and phase bunching by intense waves. Both concepts successfully describe some aspects of wave‐particle interactions but predict significantly different timescales of relativistic electron acceleration. In this study, we investigate effects that can reduce the efficiency of nonlinear interactions and bridge the gap between the predictions of these two types of models. We examine the effects of random wave phase and frequency variations observed inside whistler mode wave packets on nonlinear interactions. Our results show that phase coherence and frequency fluctuations should be taken into account to accurately model electron nonlinear resonant acceleration and that, along with wave amplitude modulation, they may reduce acceleration rates to realistic, moderate levels.
Key Points
Chorus wave phase randomly fluctuates between subpackets inside longwave packets
Wave phase coherence significantly influences the efficiency of electron acceleration via nonlinear resonant interaction
Fluctuations of wave frequency within longwave packets similarly reduce the efficiency of nonlinear resonant electron acceleration
This article presents a four-element phased-array transceiver (TRX) front-end for millimeter-wave (mm-Wave) 5G new radio (NR). The effects of amplitude-to-phase (AM-PM) and amplitude-to-amplitude ...(AM-AM) distortions on error vector magnitude (EVM) are detailed. A three-stage highly linear wideband class-AB power amplifier (PA) is described, mitigating AM-PM and AM-AM distortions without degrading other performances. A matching network embedded transmitting/receiving (T/R) switch is proposed to support time division duplex (TDD). With the proposed technique, RF switch insertion losses are reduced in both transmitter (TX) and receiving (RX) modes. In each TRX element, phase and gain controls are achieved by a 6-bit vector-modulated phase shifter (VMPS) with a phase tuning range of 360° and a 6-bit attenuator with a gain tuning range of 31.5 dB, respectively. Fabricated in 65-nm bulk CMOS, the proposed packaged TRX demonstrates the measured peak gains of 25.5/14.2 dB with the gain ripples of less than 2.5/1.9 dB across 24-29.5 GHz in the TX/RX mode. The measured peak <inline-formula> <tex-math notation="LaTeX">P_{\text {1 dB}} </tex-math></inline-formula> is 17.6 dBm with a power added efficiency (PAE) of 20.4%. The measured minimum noise figure (NF) is 4.3 dB. The TRX achieves an output power of 7.9-8.9 dBm and an EVM of −25 dB with 8 <inline-formula> <tex-math notation="LaTeX">\times </tex-math></inline-formula> 100-MHz 5G NR frequency range 2 (FR2) orthogonal frequency division multiplexing (OFDM) 64-quadrature amplitude modulation (QAM) signals across 24-29.5 GHz, covering 3rd generation partnership project (3GPP) 5G NR FR2 operating bands (i.e., n257, n258, and n261) around 26 GHz.
Many resting‐state functional magnetic resonance imaging (rs‐fMRI) studies have explored abnormal regional spontaneous brain activity in migraine. However, these results are inconsistent. To identify ...the consistent regions with abnormal neural activity, we meta‐analyzed these studies. We gathered whole‐brain rs‐fMRI studies measuring differences in the amplitude of low‐frequency fluctuations (ALFF), fractional ALFF (fALFF), or regional homogeneity (ReHo) methods. Then, we performed a voxel‐wise meta‐analysis to identify consistent abnormal neural activity in migraine by anisotropic effect size seed‐based d mapping (AES‐SDM). To confirm the AES‐SDM meta‐analysis results, we conducted two meta‐analyses: activation likelihood estimation (ALE) and multi‐level kernel density analysis (MKDA). We found that migraine showed increased regional neural activities in the bilateral postcentral gyrus (PoCG), left hippocampus (HIP.L), right pons, left superior frontal gyrus (SFG.L), triangular part of right inferior frontal gyrus (IFGtriang.R), right middle frontal gyrus (MFG.R), and left precentral gyrus (PreCG.L) and decreased regional intrinsic brain activities were exhibited in the right angular gyrus (ANG.R), left superior occipital gyrus (SOG.L), right lingual gyrus (LING.R). Moreover, the meta‐analysis of ALE further validated the abnormal neural activities in the PoCG, right pons, ANG.R, and HIP. Meta‐regression demonstrated that headache intensity was positively associated with the abnormal activities in the HIP.L, ANG.R, and LING.R. These findings suggest that migraine is associated with abnormal spontaneous brain activities of some pain‐related regions, which may contribute to a deeper understanding of the neural mechanism of migraine.
Migraine is a common neurologic disorder. We identified consistent regional neural activity alteration in migraine patients using anisotropic effect‐size seed‐based d mapping (AES‐SDM), activation likelihood estimation (ALE), and multi‐level kernel density analysis (MKDA). The findings revealed consistent abnormal brain activities which deepen our understanding of the pathological mechanism of migraine.
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