The goals of this research were to analyze cardiac sympathetic recovery patterns and evaluate whether sympathetic cardiac responses to a task challenge can be predicted using residual cardiac ...activity measured directly after the task (that is, during the recovery period). In two studies (total N = 181), we measured cardiac sympathetic activity, quantified as pre‐ejection period and RB interval, during both task performance and the 2‐min recovery period following the task. Additional analyses examined effects on the RZ interval. We found that sympathetic recovery from a task was rather quick: Cardiovascular recovery occurred within the first 30 s of the recovery period. Nevertheless, residual cardiac activity during the recovery period had predictive power for task‐related cardiac activity. This suggests that sympathetic cardiac activity during recovery may serve as a useful indicator of task‐related cardiac sympathetic activity. We discuss the implications of these findings for practical applications and the design of future studies.
There are multiple scenarios in which it is very difficult or even impossible to reliably assess sympathetic cardiac activity. This is because measures of heart contractility, such as the pre‐ejection period (PEP), RB, and RZ‐interval, are prone to signal distortion and artifacts. We found existing methods to deal with this problem insufficient and in the current paper we propose to focus on the post‐task activity as a proxy of cardiac sympathetic activity during task performance when recording impedance cardiography during a task is impossible. Furthermore, the current paper describes the patterns of cardiac sympathetic recovery for the PEP, RB, and RZ intervals, largely neglected in the recovery literature.
We report on the performance of an acousto-optically Q-switched Yb:NaY(WO4)2 crystal laser operating at 1015−1019 nm. Stable Q-switched laser action was demonstrated at pulse repetition frequencies ...(PRFs) ranging from 50 to 2 kHz, generating a pulsed output power of 2.19 W at 50 kHz, with optical-to-optical and slope efficiencies being respectively 40% and 60%. While Q-switched at the lower limit of PRF of 2 kHz, the laser was capable of producing 185.0 μJ of pulse energy, the pulse duration and peak power were 10.5 ns and 17.62 kW, respectively.
In this work, the performance of a point-to-point fiber communication system that use a directly modulated (DML) VCSEL have been studied at 2.5, 10, and 40 Gb/s. We have demonstrated that a low-cost ...error-free transmission is possible by the appropriate choice of the shape of the driving electric pulse, the extinction ratio (ER) and the On-Off Keying (OOK) signal code (Non Return to Zero-NRZ and Return to Zero-RZ). Additionally, a theoretical model is developed to research and simulate the behavior of chirped signal transmission in dispersive media such as an optical fiber. Thus, the VCSEL-DML generated frequency chirp can be handled in order to avoid the effects of the interaction of laser chirp with fiber dispersion. The transmission performance of a 40 Gb/s optical link over Standard Single-Mode Fiber (SSMF) and over Negative Non-Zero Dispersion Shifted Fiber (NZDSF(−)) is researched by simulation.
A dc-20-GHz multiple-return-to-zero digital-to-analog converter (DAC) is proposed for direct radio frequency synthesis. To minimize frequency-dependent amplitude and phase errors in the output ...summing node, which can dominate linearity performance at GHz and mm-wave frequencies, a vertically stacked tree (VST) and feed-forward (FF) path are proposed. While the VST minimizes variation in frequency response among the MSB cells, the FF path improves matching between the MSBs and LSBs, providing up to 21-dB improvement in simulated spurious-free dynamic range (SFDR) at 20 GHz. To account for additional errors introduced by process variation, the DAC utilizes per-cell calibration of both amplitude and timing. The DAC is implemented in a 0.13-μm SiGe process with an area of 6.25 mm 2 and consumes 1.91 W. After amplitude and timing calibration, >48-dB SFDR and lesser than -46 dBc intermodulation distortion are achieved from dc to 20 GHz.
In this study, the extended sinh-Gordon equation expansion method is used in constructing various exact solitary wave solutions to the Klein–Gordon–Zakharov equations. The Klein–Gordon–Zakharov ...equations is a nonlinear model describing the interaction between the Langmuir wave and the ion acoustic wave in a high-frequency plasma. We successfully construct some topological, non-topological, compound topological and non-topological, singular, compound singular solitons and singular periodic wave solutions. Under the choice of suitable values of the parameters, the 2D, 3D and contour graphs to some of the reported solutions are also plotted.
Opportunities for extraction of distances and temperatures from eclipsing binary light curves that are in standard flux units, as opposed to traditional arbitrary units, are examined. Benefits ...include (1) distance becomes an ordinary solution parameter with a standard error, (2) temperatures of both stars may be derivable in favorable circumstances, and (3) semidetached and overcontact binaries suffer no loss of distance accuracy, vis-a-vis well-detached binaries. Flux calibrations enter only for the observations, while theoretical fluxes are naturally in standard units, so confrontation of theory and observation is direct, and semiempirical quantities based on color-temperature relations are not needed. The monolithic process, called direct distance estimation (DDE), also saves time and effort by avoiding separate distance estimation steps and should lead to routine distance measurements for large numbers of eclipsing binaries (EBs). Discussions compare DDE with traditional EB distance estimation, which has been restricted to well detached binaries in most publications. Aspect dependence of spectroscopic or color temperature, as affected by tides and irradiation, is treated rigorously. A temperature-distance theorem that specifies requirements for finding temperatures and distance from EB light and velocity curves is checked by several kinds of simulations. Demonstration solutions are carried out for the overcontact binary AW UMa and the semidetached binary RZ Cnc, with discussions of temperature and distance results. Although AW UMa has many observational and structural oddities, its DDE and Hipparcos distances agree. Six DDE distances for RZ Cnc, done in several ways and for three photometric bands, fall well within the 1 sigma range of its Hipparcos distance. Interactions among calibrative errors, parameter values, and fitting discrepancies are discussed, as is proper weighting.
RZPsc is an isolated high-latitude post-T Tauri star that demonstrates a UX Ori-type photometric activity. The star shows very weak spectroscopic signatures of accretion, but at the same time ...possesses the unusual footprints of the wind in NaiDlines. In the present work we investigate new spectroscopic observations of RZPsc obtained in 2014 during two observation runs. We found variable blueshifted absorption components (BACs) in lines of the other alcali metals, Ki 7699 A and Caii IR triplet. We also confirmed the presence of a weak emission component in the H alpha line, which allowed us to estimate the mass accretion rate on the star as M< or = 7 x 10 super(-12)M sub(middo t in circle)yr super(-1). We could not reveal any clear periodicity in the appearance of BACs in sodium lines. Nevertheless, the exact coincidence of the structure and velocities of the Nai D absorptions observed with the interval of about one year suggests that such a periodicity should exist.
The erratically variable star RZ Piscium (RZ Psc) displays extreme optical dropout events and strikingly large excess infrared emission. To ascertain the evolutionary status of this intriguing star, ...we obtained observations of RZ Psc with the European Space Agency's X-ray Multi-Mirror Mission (XMM-Newton), as well as high-resolution optical spectroscopy with the Hamilton Echelle on the Lick Shane 3 m telescope and with HIRES on the Keck I 10 m telescope. The optical spectroscopy data demonstrate that RZ Psc is a pre-main sequence star with an effective temperature of 5600 75 K and log g of 4.35 0.10. The ratio of X-ray to bolometric luminosity, , lies in the range −3.7 to −3.2, consistent with ratios typical of young, solar-mass stars, thereby providing strong support for the young star status of RZ Psc. The Li absorption line strength of RZ Psc suggests an age in the range 30-50 Myr, which in turn implies that RZ Psc lies at a distance of ∼170 pc. Adopting this estimated distance, we find the Galactic space velocity of RZ Psc to be similar to the space velocities of stars in young moving groups near the Sun. Optical spectral features indicative of activity and/or circumstellar material are present in our spectra over multiple epochs, which provide evidence for the presence of a significant mass of circumstellar gas associated with RZ Psc. We suggest that the destruction of one or more massive orbiting bodies has recently occurred within 1 au of the star, and we are viewing the aftermath of such an event along the plane of the orbiting debris.
The conventional current-mode pseudo-random bit sequence (PRBS) generators suffer from high-power consumption, low output voltage swing and they are not directly compatible with the CMOS static logic ...circuit. To address this issue, this work proposes power-efficient, 2 7 -1, 20-Gb/s, half-rate pseudo-random bit sequence(HR-PRBS) generators by employing current-integrating latch circuit topology using incomplete settling at 20-Gb/s data rate implemented in 1.2 V, 65 nm CMOS. The proposed current-integrating logic latch based PRBS implementations achieves low power consumption, high speed and high voltage swing thanks to incomplete settling behaviour of the CIL circuit topology. The proposed PRBS generator implementations employing current-integrating latch topology consumes power of 0.76-mW/Gb/s while operating at 20-Gb/s data rate. The differential eye-opening of the proposed current-integrating logic (CIL) HR-PRBS generator is 1.6 V at 20-Gb/s date rate.
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