The nighttime light (NTL) satellite data have been widely
used to investigate the urbanization process. The Defense Meteorological
Satellite Program Operational Linescan System (DMSP-OLS) stable ...nighttime
light data and Suomi National Polar-orbiting Partnership Visible Infrared
Imaging Radiometer Suite (NPP-VIIRS) nighttime light data are two widely
used NTL datasets. However, the difference in their spatial resolutions and
sensor design requires a cross-sensor calibration of these two datasets for
analyzing a long-term urbanization process. Different from the traditional
cross-sensor calibration of NTL data by converting NPP-VIIRS to
DMSP-OLS-like NTL data, this study built an extended time series (2000–2018)
of NPP-VIIRS-like NTL data through a new cross-sensor calibration from
DMSP-OLS NTL data (2000–2012) and a composition of monthly NPP-VIIRS NTL
data (2013–2018). The proposed cross-sensor calibration is unique due to the
image enhancement by using a vegetation index and an auto-encoder model.
Compared with the annual composited NPP-VIIRS NTL data in 2012, our product
of extended NPP-VIIRS-like NTL data shows a good consistency at the pixel
and city levels with R2 of 0.87 and 0.95, respectively. We also found
that our product has great accuracy by comparing it with DMSP-OLS radiance-calibrated NTL (RNTL) data in 2000, 2004, 2006, and 2010. Generally, our
extended NPP-VIIRS-like NTL data (2000–2018) have an excellent spatial
pattern and temporal consistency which are similar to the composited
NPP-VIIRS NTL data. In addition, the resulting product could be easily
updated and provide a useful proxy to monitor the dynamics of demographic
and socioeconomic activities for a longer time period compared to existing
products. The extended time series (2000–2018) of nighttime light data is
freely accessible at https://doi.org/10.7910/DVN/YGIVCD (Chen et
al., 2020).
In addition to the regulation of blood pressure, the renin-angiotensin system (RAS) also plays a key role in the onset and development of insulin resistance, which is central to metabolic syndrome ...(MetS). Due to the interplay between RAS and insulin resistance, antihypertensive compounds may exert beneficial effects in the management of MetS. Food-derived bioactive peptides with RAS blocking properties can potentially improve adipose tissue dysfunction, glucose intolerance, and insulin resistance involved in the pathogenesis of MetS. This review discusses the pathophysiology of hypertension and the association between RAS and pathogenesis of the MetS. The effects of bioactive peptides with RAS modulating effects on other components of the MetS are discussed. While the in vivo reports on the effectiveness of antihypertensive peptides against MetS are encouraging, the exact mechanism by which these peptides infer their effects on glucose and lipid handling is mostly unknown. Therefore, careful design of experiments along with standardized physiological models to study the effect of antihypertensive peptides on insulin resistance and obesity could help to clarify this relationship.
Voltage-gated sodium (Nav) channels initiate and propagate action potentials. Here, we present the cryo-EM structure of EeNav1.4, the Nav channel from electric eel, in complex with the β1 subunit at ...4.0 Å resolution. The immunoglobulin domain of β1 docks onto the extracellular L5I and L6IV loops of EeNav1.4 via extensive polar interactions, and the single transmembrane helix interacts with the third voltage-sensing domain (VSDIII). The VSDs exhibit “up” conformations, while the intracellular gate of the pore domain is kept open by a digitonin-like molecule. Structural comparison with closed NavPaS shows that the outward transfer of gating charges is coupled to the iris-like pore domain dilation through intricate force transmissions involving multiple channel segments. The IFM fast inactivation motif on the III-IV linker is plugged into the corner enclosed by the outer S4-S5 and inner S6 segments in repeats III and IV, suggesting a potential allosteric blocking mechanism for fast inactivation.
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•4.0 Å structure of the Nav1.4-β1 complex from electric eel with an open pore•β1 interacts with the extracellular loops and the third voltage sensor of EeNav1.4•The resolved voltage sensors in repeats III and IV both exhibit “up” conformations•A potential allosteric blocking mechanism for fast inactivation of Nav channels
Structural analysis of the eel Nav1.4 channel offers insights into the electromechanical coupling mechanism of voltage-gated sodium channels.
Distributed denial-of-service (DDoS) defense is still a difficult problem though it has been extensively studied. The existing approaches are not capable of detecting various types of DDoS attacks. ...In particular, new emerging sophisticated DDoS attacks (e.g., Crossfire) constructed by low-rate and short-lived benign traffic are even more challenging to capture. Moreover, it is difficult to enforce realtime defense to throttle these detected attacks since the attack traffic can be concealed in benign traffic. Software defined networking (SDN) opens a new door to address these issues. In this paper, we propose Reinforcing Anti-DDoS Actions in Realtime (RADAR) to detect and throttle DDoS attacks via adaptive correlation analysis built upon unmodified commercial off-the-shelf SDN switches. It is a practical system to defend against a wide range of flooding-based DDoS attacks, e.g., link flooding (including Crossfire), SYN flooding, and UDP-based amplification attacks, while requiring neither modifications in SDN switches/protocols nor extra appliances. It accurately detects attacks by identifying attack features in suspicious flows, and locates attackers (or victims) to throttle the attack traffic by adaptive correlation analysis. We implement RADAR prototype using open source Floodlight controller, and evaluate its performance under various DDoS attacks by real hardware testbed based experiments. We observe that our scheme can successfully detect and effectively defend against various DDoS attacks with acceptable overhead.
There is growing evidence that ketone bodies, which are derived from fatty acid oxidation and usually produced in fasting state or on high-fat diets have broad neuroprotective effects. Although the ...mechanisms underlying the neuroprotective effects of ketone bodies have not yet been fully elucidated, studies in recent years provided abundant shreds of evidence that ketone bodies exert neuroprotective effects through possible mechanisms of anti-oxidative stress, maintaining energy supply, modulating the activity of deacetylation and inflammatory responses. Based on the neuroprotective effects, the ketogenic diet has been used in the treatment of several neurological diseases such as refractory epilepsy, Parkinson's disease, Alzheimer's disease, and traumatic brain injury. The ketogenic diet has great potential clinically, which should be further explored in future studies. It is necessary to specify the roles of components in ketone bodies and their therapeutic targets and related pathways to optimize the strategy and efficacy of ketogenic diet therapy in the future.
The voltage-gated calcium channel Ca(v)1.1 is engaged in the excitation-contraction coupling of skeletal muscles. The Ca(v)1.1 complex consists of the pore-forming subunit α1 and auxiliary subunits ...α2δ, β, and γ. We report the structure of the rabbit Ca(v)1.1 complex determined by single-particle cryo-electron microscopy. The four homologous repeats of the α1 subunit are arranged clockwise in the extracellular view. The γ subunit, whose structure resembles claudins, interacts with the voltage-sensing domain of repeat IV (VSD(IV)), whereas the cytosolic β subunit is located adjacent to VSD(II) of α1. The α2 subunit interacts with the extracellular loops of repeats I to III through its VWA and Cache1 domains. The structure reveals the architecture of a prototypical eukaryotic Ca(v) channel and provides a framework for understanding the function and disease mechanisms of Ca(v) and Na(v) channels.
At present, there are many aerial-view datasets that contain motion data from vehicles in a variety of traffic scenarios. However, there are few datasets that have been collected under different ...weather conditions in an urban mixed-traffic scenario. In this study, we propose a framework for extracting vehicle motion data from UAV videos captured under various weather conditions. With this framework, we improve YOLOv5 (you only look once) with image-adaptive enhancement for detecting vehicles in different environments. In addition, a new vehicle-tracking algorithm called SORT++ is proposed to extract high-precision vehicle motion data from the detection results. Moreover, we present a new dataset that includes 7133 traffic images (1311 under sunny conditions, 961 under night, 3366 under rainy, and 1495 under snowy) of 106,995 vehicles. The images were captured by a UAV to evaluate the proposed method for vehicle orientation detection. In order to evaluate the accuracy of the extracted traffic data, we also present a new dataset of four UAV videos, each having 30,000+ frames, of approximately 3K vehicle trajectories collected under sunny, night, rainy, and snowy conditions, respectively. The experimental results show the high accuracy and stability of the proposed methods.
The ryanodine receptors （RyRs） are intracellular calcium channels responsible for rapid release of Ca^2＋ from the sarcoplasmic/endoplasmic reticulum （SR/ER） to the cytoplasm, which is essential for ...the excitation-contraction （E-C） coupling of cardiac and skeletal muscles. The near-atomic resolution structure of closed RyRI revealed the molecular details of this colossal channel, while the long-range allosteric gating mechanism awaits elucidation. Here, we report the cryo-EM structures of rabbit RyR1 in three closed conformations at about 4 A° resolution and an open state at 5.7 A°. Comparison of the closed RyR1 structures shows a breathing motion of the cytoplasmic platform, while the channel domain and its contiguous Central domain remain nearly unchanged. Comparison of the open and closed structures shows a dilation of the S6 tetrahelical bundle at the cytoplasmic gate that leads to channel opening. During the pore opening, the cytoplasmic ＂O-ring＂ motif of the channel domain and the U-motif of the Central domain exhibit coupled motion, while the Central domain undergoes domain-wise displacement. These structural analyses provide important insight into the E-C coupling in skeletal muscles and identify the Central domain as the transducer that couples the conformational changes of the cytoplasmic platform to the gating of the central pore.
Currently, chemotherapy is the main treatment for tumors, but there are still problems such as unsatisfactory chemotherapy results, susceptibility to drug resistance, and serious adverse effects. ...Natural compounds have numerous pharmacological activities which are important sources of drug discovery for tumor treatment. The combination of chemotherapeutic drugs and natural compounds is gradually becoming an important strategy and development direction for tumor treatment. In this paper, we described the role of natural compounds in combination with chemotherapeutic drugs in synergizing, reducing drug resistance, mitigating adverse effects and related mechanisms, and providing new insights for future oncology research.
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