Abstract
We present the latest updates to the PLACET3 tracking package, which focus on the impact of both transverse and longitudinal wakefields on a beam travelling through accelerating and ...decelerating structures. The main focus of this update was the first implementation of 6D tracking through Power Extraction and Transfer Structures (PETS) for the Compact Linear Collider (CLIC), which is described through short and long-range longitudinal wakefields. Additionally, we present the impact of different numerical schemes on the computation of wakefields in accelerating structures.
The dynamics of an isothermal gas suspension is studied. A spherically symmetric stationary submodel is derived and partially integrated. In a barochronous case, this submodel is fully integrated and ...results are discussed. Different modes of motion are analytically described in the barochronous case. The interpretation of the solutions is proposed. We highlight three essentially different modes of motion. In the first mode, we have a dispersion of gas suspension from the origin with a relaxation of velocities and leading to the uniform motion. In the second mode, phases focus in the origin with finite nonzero velocities and infinitely increasing densities. In the third mode, phases are interpenetrating to each other and decelerating due to the friction force, that leads to an accumulation of particles and an unlimited increase of densities in different nonzero raduises with zero velocities.
Abstract
In this communication, we have explored spatially homogeneous, anisotropic Bianchi-II space-time in
f(R, T)
theory of gravity. Here, we have obtained an explicit solution of the field ...equations of
f(R, T)
theory with time dependent fractional linear varying deceleration parameter (FLVDP) i.e.
q(t)
. The accelerating expanding nature of the cosmos has been also discussed under the suitable assumption
q
(
t
)
=
α
(
1
−
t
)
1
+
t
, here
α
> 0. It is observed that the universe was originated from a singularity in the past and is expanding at an accelerating rate. The FLVDP depicts a transitional phase i.e., early deceleration to the current accelerating phase.
Purpose
Increased vagal activity plays a prominent role in vasovagal syncope (VVS). The aim of this study was to characterize vagal function in VVS by evaluating the heart rate (HR) deceleration ...capacity (DC) and the HR deceleration runs (DRs) in patients with VVS between attacks.
Methods
A total of 188 consecutive VVS patients were enrolled in the study, of whom 129 had positive head-up tilt test (HUTT); 132 healthy participants were enrolled as controls. DC, DRs (DR2, i.e., episodes of 2 consecutive beat-to-beat HR decelerations), and the sum of DR8-10 (very long DR VLDR) were calculated using 24-h electrograms. Clinical characteristics, DC, and DRs were compared among syncope groups and controls.
Results
Patients with VVS had higher DC (10.63 ± 2.1 vs. 6.58 ± 1.7 ms;
P
< 0.001) and lower minimum HR and DR6-10 than controls. No significant differences in DC or DR6-10 were found between the patients with positive and those with negative HUTT results. In multivariate logistic regression analysis, minimum HR ≥ 40 bpm (odds ratio OR 0.408, 95% confidence interval CI 0.167–0.989;
P
= 0.048), daytime DC ≥ 7.37 ms (OR 3.040, 95% CI 1.220–7.576;
P
= 0.013), and VLDR ≥ 0.046% (OR 0.306, 95% CI 0.138–0.679;
P
= 0.004) were demonstrated to be risk factors significantly associated with VVS.
Conclusion
Compared to healthy controls, patients with VVS demonstrated distinct HR deceleration profiles between attacks, including overall higher DC and lower DR6-10.
Attributed to the ability of inertia provision and good regulation performance, the virtual synchronous generator (VSG) has been proven as a promising solution to the problems introduced by using ...converter interfaced generation. Although the small-signal stability control of the VSG has been widely analyzed, the transient characteristics still needs more study, which belongs to a large-signal problem. In this article, the transient angle stability control of the VSG is investigated. Two possible VSG emulation methods, i.e., the power-emulation and the torque-emulation, are compared from the perspective of transient characteristics. Then, the transient of the VSG internal voltage and its impact on the transient angle stability are quantitatively studied in details. Thereafter, an enhanced VSG controller is proposed, where a large-signal analysis is also presented to evaluate its influence on the acceleration and deceleration areas. Finally, the analysis and effectiveness of the enhanced VSG method are validated by the experimental results.
Brief repeated fetal hypoxaemia during labour can trigger intrapartum decelerations of the fetal heart rate (FHR) via the peripheral chemoreflex or the direct effects of myocardial hypoxia, but the ...relative contribution of these two mechanisms and how this balance changes with evolving fetal compromise remain unknown. In the present study, chronically instrumented near‐term fetal sheep received surgical vagotomy (n = 8) or sham vagotomy (control, n = 11) to disable the peripheral chemoreflex and unmask myocardial hypoxia. One‐minute complete umbilical cord occlusions (UCOs) were performed every 2.5 min for 4 h or until arterial pressure fell below 20 mmHg. Hypotension and severe acidaemia developed progressively after 65.7 ± 7.2 UCOs in control fetuses and 49.5 ± 7.8 UCOs after vagotomy. Vagotomy was associated with faster development of metabolic acidaemia and faster impairment of arterial pressure during UCOs without impairing centralization of blood flow or neurophysiological adaptation to UCOs. During the first half of the UCO series, before severe hypotension developed, vagotomy was associated with a marked increase in FHR during UCOs. After the onset of evolving severe hypotension, FHR fell faster in control fetuses during the first 20 s of UCOs, but FHR during the final 40 s of UCOs became progressively more similar between groups, with no difference in the nadir of decelerations. In conclusion, FHR decelerations were initiated and sustained by the peripheral chemoreflex at a time when fetuses were able to maintain arterial pressure. After the onset of evolving hypotension and acidaemia, the peripheral chemoreflex continued to initiate decelerations, but myocardial hypoxia became progressively more important in sustaining and deepening decelerations.
Key points
Brief repeated hypoxaemia during labour can trigger fetal heart rate decelerations by either the peripheral chemoreflex or myocardial hypoxia, but how this balance changes with fetal compromise is unknown.
Reflex control of fetal heart rate was disabled by vagotomy to unmask the effects of myocardial hypoxia in chronically instrumented fetal sheep. Fetuses were then subjected to repeated brief hypoxaemia consistent with the rates of uterine contractions during labour.
We show that the peripheral chemoreflex controls brief decelerations in their entirety at a time when fetuses were able to maintain normal or increased arterial pressure.
The peripheral chemoreflex still initiated decelerations even after the onset of evolving hypotension and acidaemia, but myocardial hypoxia made an increasing contribution to sustain and deepen decelerations.
figure legend We tested the relative contributions of the peripheral chemoreflex and myocardial hypoxia to intrapartum fetal heart rate decelerations by performing surgical vagotomy in fetal sheep to disable the peripheral chemoreflex and unmask myocardial hypoxia. These studies showed that the peripheral chemoreflex initiated and sustained decelerations in healthy fetuses. In contrast, after fetuses developed evolving cardiovascular compromise and were at risk of permanent brain injury, the peripheral chemoreflex initiated decelerations, but myocardial hypoxia made an increasing contribution to sustain and deepen decelerations.
•The FOT data from 46 participants was used to analyze the effectiveness of drivers’ characteristics, including gender, occupation and experience, on driving behaviors on a freeway deceleration ...lane.•Male drivers recognize risk more than female drivers, and also have more aggressive driving tendencies.•Professional drivers and experienced drivers made the last lane-change as early as possible to enter the deceleration lane.•The speed of the vehicles entering the exit ramp was significantly higher than the design speed.•The minimum TTC and the maximum deceleration show that the certain driving behaviors are related to high traffic risk.
Deceleration lanes improve traffic flow by reducing interference, increasing capacity and enhancing safety. However, accident rates are higher on these interchange segments than on other freeway segments. It is important to attempt to reduce traffic accidents on these interchange segments by further exploring the behavior of different types of drivers on a highway deceleration lane. In this study, with field operational test (FOT) data from 89 driving instances (derived from 46 participants driving the test road twice) on a typical freeway deceleration lane, section speed profiles, vehicle trajectories, lane position and other key parameters were obtained. The lane-change characteristics and speed profiles of drivers with different genders, occupations and experiences were analyzed. The significant disparities between them reflects the risk associated with different groups of drivers. The study shows that male drivers changed to the outside lane earlier; professional drivers and experienced drivers made the last lane change as early as possible to enter the deceleration lane; and the speed of the vehicles entering the exit ramp was significantly higher than the speed limit. This research work provides ground truth data for deceleration lane design, driver ability training and off-ramp traffic safety management.
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