1,595 research outputs found
Insights into the pulmonary vascular complications of heart failure with preserved ejection fraction
Pulmonary hypertension in the setting of heart failure with preserved ejection fraction (PH-HFpEF) is a growing public health problem that is increasing in prevalence. While PH-HFpEF is defined by a high mean pulmonary artery pressure, high left ventricular end-diastolic pressure and a normal ejection fraction, some HFpEF patients develop PH in the presence of pulmonary vascular remodelling with a high transpulmonary pressure gradient or pulmonary vascular resistance. Ageing, increased left atrial pressure and stiffness, mitral regurgitation, as well as features of metabolic syndrome, which include obesity, diabetes and hypertension, are recognized as risk factors for PH-HFpEF. Qualitative studies have documented that patients with PH-HFpEF develop more severe symptoms than those with HFpEF and are associated with more significant exercise intolerance, frequent hospitalizations, right heart failure and reduced survival. Currently, there are no effective therapies for PH-HFpEF, although a number of candidate drugs are being evaluated, including soluble guanylate cyclase stimulators, phosphodiesterase type 5 inhibitors, sodium nitrite and endothelin receptor antagonists. In this review we attempt to provide an updated overview of recent findings pertaining to the pulmonary vascular complications in HFpEF in terms of clinical definitions, epidemiology and pathophysiology. Mechanisms leading to pulmonary vascular remodelling in HFpEF, a summary of pre-clinical models of HFpEF and PH-HFpEF, and new candidate therapeutic strategies for the treatment of PH-HFpEF are summarized
Tunable current circulation in triangular quantum-dot metastructures
Advances in fabrication and control of quantum dots allow the realization of
metastructures that may exhibit novel electrical transport phenomena. Here, we
investigate the electrical current passing through one such metastructure, a
system composed of quantum dots placed at the vertices of a triangle. The wave
natural of quantum particles leads to internal current circulation within the
metastructure in the absence of any external magnetic field. We uncover the
relation between its steady-state total current and the internal circulation.
By calculating the electronic correlations in quantum transport exactly, we
present phase diagrams showing where different types of current circulation can
be found as a function of the correlation strength and the coupling between the
quantum dots. Finally, we show that the regimes of current circulation can be
further enhanced or reduced depending on the local spatial distribution of the
interactions, suggesting a single-particle scattering mechanism is at play even
in the strongly-correlated regime. We suggest experimental realizations of
actual quantum-dot metastructures where our predictions can be directly tested.Comment: 5 pages, 4 figures, the Supplemental Information is attached at the
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Enhancement in the Detection Ability of Metal Oxide Sensors Using DefectâRich Polycrystalline Nanofiber Devices
[[abstract]]The development of SnO2 and TiO2 polycrystalline nanofiber devices (PNFDs) has been widely researched as a method of protecting humans from household air pollution. PNFDs have three significant advantages. The nanofibers before the annealing process are polymerârich materials, which can be used as particulate material (PM) filters. The multiporous nanofibers fabricated by the annealing process have numerous defects that can serve as generationârecombination centers for electronâhole pairs, enabling the PNFDs to serve as multipleâwavelength light (from 365 to 940 nm) detectors. Lastly, the numerous surface/interface defects can drastically enhance the toxic gas detection ability. The toxic gas detection range of PNFDs for CO(g) and NO(g) is from 400 to 50 ppm and 400 to 50 ppb, respectively. Quick response times and recovery properties are key parameters for commercial applications. The recovery time of NO(g) detection can be improved from 1 ks to 40 s and the PNFD operating temperature lowered to 50 °C. These results indicate that SnO2 and TiO2 PNFDs have good potential for commercialization and use as toxic gas and photon sensors in daily lives.[[notice]]èŁæŁćź
Modality-Independent Teachers Meet Weakly-Supervised Audio-Visual Event Parser
Audio-visual learning has been a major pillar of multi-modal machine
learning, where the community mostly focused on its modality-aligned setting,
i.e., the audio and visual modality are both assumed to signal the prediction
target. With the Look, Listen, and Parse dataset (LLP), we investigate the
under-explored unaligned setting, where the goal is to recognize audio and
visual events in a video with only weak labels observed. Such weak video-level
labels only tell what events happen without knowing the modality they are
perceived (audio, visual, or both). To enhance learning in this challenging
setting, we incorporate large-scale contrastively pre-trained models as the
modality teachers. A simple, effective, and generic method, termed Visual-Audio
Label Elaboration (VALOR), is innovated to harvest modality labels for the
training events. Empirical studies show that the harvested labels significantly
improve an attentional baseline by 8.0 in average F-score (Type@AV).
Surprisingly, we found that modality-independent teachers outperform their
modality-fused counterparts since they are noise-proof from the other
potentially unaligned modality. Moreover, our best model achieves the new
state-of-the-art on all metrics of LLP by a substantial margin (+5.4 F-score
for Type@AV). VALOR is further generalized to Audio-Visual Event Localization
and achieves the new state-of-the-art as well. Code is available at:
https://github.com/Franklin905/VALOR
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