In this paper, we study the so-called Ricci-inverse gravity, which is a very novel type of fourth-order gravity proposed recently. In particular, we are able to figure out both isotropically and ...anisotropically inflating universes to this model. More interestingly, these solutions are shown to be free from a singularity problem. However, stability analysis based on the dynamical system method shows that both isotropic and anisotropic inflation of this model turn out to be unstable against field perturbations. This result implies a no-go theorem for both isotropic and anisotropic inflation in the Ricci-inverse gravity.
In this paper, we propose an extension of the Ricci-inverse gravity, which has been proposed recently as a very novel type of fourth-order gravity, by introducing a second order term of the so-called ...anticurvature scalar as a correction. The main purpose of this paper is that we would like to see whether the extended Ricci-inverse gravity model admits the homogeneous and isotropic Friedmann–Lemaitre–Robertson–Walker metric as its stable inflationary solution. However, a no-go theorem for inflation in this extended Ricci-inverse gravity is shown to appear through a stability analysis based on the dynamical system method. As a result, this no-go theorem implies that it is impossible to have such stable inflation in this extended Ricci-inverse gravity model.
In this paper, we extend our investigation of the validity of the cosmic no-hair conjecture within non-canonical anisotropic inflation. As a result, we are able to figure out an exact Bianchi type I ...solution to a power-law
k
-inflation model in the presence of unusual coupling between scalar and electromagnetic fields as
-
f
2
(
ϕ
)
F
μ
ν
F
μ
ν
/
4
. Furthermore, stability analysis based on the dynamical system method indicates that the obtained solution does admit stable and attractive hairs during an inflationary phase and therefore violates the cosmic no-hair conjecture. Finally, we show that the corresponding tensor-to-scalar ratio of this model turns out to be highly consistent with the observational data of the Planck 2018.
Myocardial fibrosis refers to a variety of quantitative and qualitative changes in the interstitial myocardial collagen network that occur in response to cardiac ischaemic insults, systemic diseases, ...drugs, or any other harmful stimulus affecting the circulatory system or the heart itself. Myocardial fibrosis alters the architecture of the myocardium, facilitating the development of cardiac dysfunction, also inducing arrhythmias, influencing the clinical course and outcome of heart failure patients. Focusing on myocardial fibrosis may potentially improve patient care through the targeted diagnosis and treatment of emerging fibrotic pathways. The European Commission funded the FIBROTARGETS consortium as a multinational academic and industrial consortium with the primary aim of performing a systematic and collaborative search of targets of myocardial fibrosis, and then translating these mechanisms into individualized diagnostic tools and specific therapeutic pharmacological options for heart failure. This review focuses on those methodological and technological aspects considered and developed by the consortium to facilitate the transfer of the new mechanistic knowledge on myocardial fibrosis into potential biomedical applications.
In Vietnam, landslides frequently occur on cut slopes along the road system during the rainy season. An understanding of the contributing factors and triggering mechanisms is essential so that ...effective measures can be taken to stabilize cut slopes and mitigate impacts caused by landslides. This study uses as a research subject the largest deep-seated landslide triggered by heavy rainfall on July 21, 2018, and the subsequent sliding induced by 5-day continuous rainfall events on the Halong–Vandon expressway. We examined the causative factors, failure mechanisms, and characteristics of the landslides through detailed geological investigation, unmanned aerial vehicle (UAV) surveys, and analysis of data from geology, geomorphology, well-prepared documents of rainfall events, and the expressway project. Results show that the heavy rainfall was the triggering factor for both events while slope cutting was the main landslide causative factor. The slump-type landslides occurred on weathered limestone layers that were parallel to the dip-slope direction of the strata. Geological settings of highly fractured and weathered sandstone, siltstone, and limestone combined with the development of karst caves favored the buildup of groundwater levels in deep layers, thereby causing deep-seated landslides. The analysis shows that in addition to geological factors, the landslide occurrences resulted from anthropogenic effects including the improper design of the calculation method for safety factors in road construction and quarrying activities. Site evidence and UAV photos also reveal that the July 21 landslide body on the lower slope was reactivated to travel downward due to the dynamic effect of the subsequent sliding on July 31. Based on numerical analysis using the Plaxis 2D model, an estimated sliding surface similar to the actual plane was simulated for the entire slope. Furthermore, the study presents an appropriate solution that has been applied to slope stabilization.
Conventional current source inverter (CSI) suffers from open-circuit problem during switch transition. Thus, overlap-time should be inserted in the gate signals for safe commutation. The overlap-time ...distorts output current waveforms and increases total harmonic distortion of output current. Moreover, it reduces the current source utilization of the inverter. To solve these problems, this article proposes a new three-phase four-leg switching-cell (SC) CSI, abbreviated as H8-SC-CSI. With the help of the SC structure, the reliability of the proposed inverter is greatly enhanced as open-circuit concerns are eliminated. In addition, with the intrinsic voltage clamping action of the SC structure, switch voltage overshoot at turn- off is mitigated. In the proposed CSI, the switch overlap-time can be minimized or eliminated because the inductor current can flow through the SC capacitors. A 1.2 kW prototype inverter is designed and tested to verify the feasibility of the circuit.
In this article, a novel high-reliability single-phase dual-output current source inverter is presented. By using the switching-cell (SC) structure in the proposed topology, the overlap-time between ...switching transition can be minimized or eliminated. This improves the quality of ac output currents, efficiency, and dc-source utilization. Additionally, the capacitors in SC structure can help to reduce dv / dt of power switches and clamp the overshoot voltage under open-circuit problems, thus improving reliability. Two modes of common and different frequency operations are considered and detailed pulsewidth modulation schemes are presented. A 650-W hardware prototype was built and tested to verify the performance of the proposed inverter, and the results are compared with conventional single-phase dual-output current source inverters.
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