The voltage-frequency coupled transient stability and risk assessment issues of weak grid-connected large-scale renewable energy plants (REPs) during low voltage ride through (LVRT) have received ...little attention to date. The shape and mechanism of voltage-frequency coupled transient instability during LVRT are investigated in detail by the voltage-vector-triangle graphic (VTG) method utilized in this article, which avoids complex mathematical calculations. In addition, the margin of the transmission line's voltage angle (MTVA) is defined in this article and is then used to quantitatively assess the transient instability risk of the large-scale REPs during LVRT. Furthermore, the expressions of the MTVA are deduced under different conditions and the major influencing factors, which resulted in instability risk, are determined correspondingly. On this basis, the transient instability risk assessment standard of the large-scale REPs is built and the instability risk minimized scheduling strategy is proposed in this article, which does not change the internal control structure and parameters of the REPs during LVRT. Finally, both the correctness of the VTG method and the risk assessment standard, and the effectiveness of the scheduling strategy proposed in this article are validated by experiments and simulations.
In order to explore the impact load and instantaneous fluid pressure of transient flow on pump station system under the nonregulative operating conditions, the transient characteristics of an axial ...flow pump during start-up process are investigated experimentally and numerically. To simulate transient flow of the pump, the rational speed is set by force coupling. In order to simulate the movement of the gate with two flap doors attached, the moving mesh technique is adopted. The results of numerical simulation agree well with the experimental data. During the start-up transient process, the transient characteristics parameters, such as pump rotational speed, head, and flow rate change significantly. Transient impact head rises to a peak of 1.87 times the rated head as the rotational speed reaches the rated speed. The whole impeller passage is full of recirculation, flow separation and vortices. The pressure distribution of the impeller blade changes obviously. In the process of pump start-up, the vortex core zones gradually increase, massively appear at the leading edges of the blade and in the passage of the impeller at t=0.6 s, and then decrease. Our studies could help to avoid pump vibration and blade crack in engineering.
•The rotational speed was estimated from force coupling.•Transient impact peaks at the rated speed during the pump startup.•Recirculation and flow separation appeared in the whole impeller passage.•The vortex core zones increase at the leading edges of the blade then decrease.
Microglial activation and its-driven neuroinflammation are characteristic pathogenetic features of neurodiseases, including focal cerebral ischemia. The Artemisia asiatica (Asteraceae) extract and ...its active component, eupatilin, are well-known to reduce inflammatory responses. But the therapeutic potential of eupatilin against focal cerebral ischemia is not known, along with its anti-inflammatory activities on activated microglia. In this study, we investigated the neuroprotective effect of eupatilin on focal cerebral ischemia through its anti-inflammation, particularly on activated microglia, employing a transient middle cerebral artery occlusion/reperfusion (tMCAO), combined with lipopolysaccharide-stimulated BV2 microglia. Eupatilin exerted anti-inflammatory responses in activated BV2 microglia, in which it reduced secretion of well-known inflammatory markers, including nitrite, IL-6, TNF-α, and PGE2, in a concentration-dependent manner. These observed in vitro effects of eupatilin led to in vivo neuroprotection against focal cerebral ischemia. Oral administration of eupatilin (10 mg/kg) in a therapeutic paradigm significantly reduced brain infarction and improved neurological functions in tMCAO-challenged mice. The same benefit was also observed when eupatilin was given even within 5 hours after MCAO induction. In addition, the neuroprotective effects of a single administration of eupatilin (10 mg/kg) immediately after tMCAO challenge persisted up to 3 days after tMCAO. Eupatilin administration reduced the number of Iba1-immunopositive cells across ischemic brain and induced their morphological changes from amoeboid into ramified in the ischemic core, which was accompanied with reduced microglial proliferation in ischemic brain. Eupatilin suppressed NF-κB signaling activities in ischemic brain by reducing IKKα/β phosphorylation, IκBα phosphorylation, and IκBα degradation. Overall, these data indicate that eupatilin is a neuroprotective agent against focal cerebral ischemia through the reduction of microglial activation.
With an increase in the ageing population, there is a rise in the burden of cardiovascular disease. Age and Ageing have compiled collections of their key cardiovascular themed papers. The first Age ...and Ageing Cardiovascular Collection focussed on blood pressure, coronary heart disease and heart failure. In this second collection, publications since 2011 were selected with emphasis on atrial fibrillation, transient ischaemic attack (TIA) and stroke. The prevalence of TIA and stroke increases as people get older. In this commentary we summarise studies published in Age and Ageing that bring to the fore the need for a multidisciplinary, person-centred approach to care, conscientious identification of risk factors and their management and prevention strategies, which will inform policy ultimately reducing the burden of cost placed by stroke care on healthcare financing. Read the latest Cardiovascular Collection here.
Abstract
We present Hubble Space Telescope ultraviolet and infrared observations of eight fast radio burst (FRB) host galaxies with subarcsecond localizations, including the hosts of three known ...repeating FRBs. We quantify their spatial distributions and locations with respect to their host galaxy light distributions, finding that they occur at moderate host-normalized offsets of 1.4
r
e
(0.6, 2.1
r
e
; 68% interval) and on fainter regions of their hosts in terms of IR light but overall trace the radial distribution of IR light in their galaxies. The FRBs in our tested distribution do not clearly trace the distributions of any other transient population with known progenitors and are statistically distinct from the locations of LGRBs, H-poor SLSNe, SGRBs, and Ca-rich transients. We further find that most FRBs are not in regions of elevated local star formation rates and stellar mass surface densities in comparison to the mean global values of their hosts. We also place upper limits on the IR flux at the FRB positions of
m
IR
≳ 24.8–27.6 AB mag, constraining both satellite and background galaxies to luminosities well below the host luminosity of FRB 121102. We find that 5/8 FRB hosts exhibit clear spiral arm features in IR light, and that the positions of all well-localized FRBs located in such hosts are consistent with their spiral arms, although not on their brightest regions. Our results do not strongly support the primary progenitor channel of FRBs being connected with either the most massive (stripped-envelope) stars or events that require kicks and long delay times (neutron star mergers).
Cigarette smoke (CS) inhalation causes an early inflammatory response in rodent airways by stimulating capsaicin-sensitive sensory neurons that express transient receptor potential cation channel, ...subfamily V, member 1 (TRPV1) through an unknown mechanism that does not involve TRPV1. We hypothesized that 2 alpha,beta-unsaturated aldehydes present in CS, crotonaldehyde and acrolein, induce neurogenic inflammation by stimulating TRPA1, an excitatory ion channel coexpressed with TRPV1 on capsaicin-sensitive nociceptors. We found that CS aqueous extract (CSE), crotonaldehyde, and acrolein mobilized Ca2+ in cultured guinea pig jugular ganglia neurons and promoted contraction of isolated guinea pig bronchi. These responses were abolished by a TRPA1-selective antagonist and by the aldehyde scavenger glutathione but not by the TRPV1 antagonist capsazepine or by ROS scavengers. Treatment with CSE or aldehydes increased Ca2+ influx in TRPA1-transfected cells, but not in control HEK293 cells, and promoted neuropeptide release from isolated guinea pig airway tissue. Furthermore, the effect of CSE and aldehydes on Ca2+ influx in dorsal root ganglion neurons was abolished in TRPA1-deficient mice. These data identify alpha,beta-unsaturated aldehydes as the main causative agents in CS that via TRPA1 stimulation mediate airway neurogenic inflammation and suggest a role for TRPA1 in the pathogenesis of CS-induced diseases.
Abstract
The next generation of wide-field cosmic microwave background (CMB) surveys are uniquely poised to open a new window into time-domain astronomy in the millimeter band. Here, we explore the ...discovery phase space for extragalactic transients with near-term and future CMB experiments to characterize the expected population. We use existing millimeter-band light curves of known transients (gamma-ray bursts, tidal disruption events, fast blue optical transients (FBOTs), neutron star mergers) and theoretical models, in conjunction with known and estimated volumetric rates. Using Monte Carlo simulations of various CMB survey designs (area, cadence, depth, duration) we estimate the detection rates and the resulting light-curve characteristics. We find that existing and near-term surveys will find tens to hundreds of long-duration gamma-ray bursts (LGRBs), driven primarily by detections of the reverse shock emission, and including off-axis LGRBs. Next-generation experiments (CMB-S4, CMB-HD) will find tens of FBOTs in the nearby universe and will detect a few tidal disruption events. CMB-HD will additionally detect a small number of short gamma-ray bursts, where these will be discovered within the detection volume of next-generation gravitational wave experiments like the Cosmic Explorer.
The association of genetic polymorphisms and clopidogrel efficacy in patients with ischemic stroke or transient ischemic attack (TIA) remains controversial. We performed a systematic review and ...meta-analysis to assess the association between genetic polymorphisms, especially CYP2C19 genotype, and clopidogrel efficacy for ischemic stroke or TIA.
We conducted a comprehensive search of PubMed and EMBASE from their inceptions to June 24, 2016. Studies that reported clopidogrel-treated patients with stroke or TIA and with information on genetic polymorphisms were included. The end points were stroke, composite vascular events, and any bleeding.
Among 15 studies of 4762 patients with stroke or TIA treated with clopidogrel, carriers of CYP2C19 loss-of-function alleles (*2, *3, and *8) were at increased risk of stroke in comparison with noncarriers (12.0% versus 5.8%; risk ratio, 1.92, 95% confidence interval, 1.57-2.35; P<0.001). Composite vascular events were also more frequent in carriers of CYP2C19 loss-of-function alleles than in noncarriers (13.7% versus 9.4%; risk ratio, 1.51, 95% confidence interval, 1.10-2.06; P=0.01), whereas bleeding rates were similar (2.4% versus 3.1%; risk ratio, 0.89, 95% confidence interval, 0.58-1.35; P=0.59). There was no evidence of statistical heterogeneity among the included studies for stroke, but there was for composite vascular events. Genetic variants other than CYP2C19 were not associated with clinical outcomes, with the exception that significant associations of PON1, P2Y12, and COX-1 with outcomes were observed in 1 study.
Carriers of CYP2C19 loss-of-function alleles are at greater risk of stroke and composite vascular events than noncarriers among patients with ischemic stroke or TIA treated with clopidogrel.
The short-term incidence of ischemic stroke after a transient ischemic attack (TIA) is high. However, data on the long-term incidence are not well known but are needed to guide preventive strategies.
...Patients with first-time TIA (index date) in the Danish Stroke Registry (January 2014-December 2020) were included and matched 1:4 with individuals from the background population and 1:1 with patients with a first-time ischemic stroke on the basis of age, sex, and calendar year. The incidences of ischemic stroke and mortality from index date were estimated by Aalen-Johansen and Kaplan-Meier estimators, respectively, and compared between groups using multivariable Cox regression.
We included 21 500 patients with TIA, 86 000 patients from the background population, and 21 500 patients with ischemic stroke (median age, 70.8 years 25th-75th percentile, 60.8-78.7; 53.1% males). Patients with TIA had more comorbidities than the background population, yet less than the control stroke population. The 5-year incidence of ischemic stroke after TIA (6.1% 95% CI, 5.7-6.5) was higher than the background population (1.5% 95% CI, 1.4-1.6,
<0.01; hazard ratio, 5.14 95% CI, 4.65-5.69) but lower than the control stroke population (8.9% 95% CI, 8.4-9.4,
<0.01; hazard ratio, 0.58 95% CI, 0.53-0.64). The 5-year mortality for patients with TIA (18.6% 95% CI, 17.9-19.3) was higher than the background population (14.8% 95% CI, 14.5-15.1,
<0.01; hazard ratio, 1.26 95% CI, 1.20-1.32) but lower than the control stroke population (30.1% 95% CI, 29.3-30.9,
<0.01; hazard ratio, 0.41 95% CI, 0.39-0.44).
Patients with first-time TIA had an ischemic stroke incidence of 6.1% during the 5-year follow-up period. After adjustment for relevant comorbidities, this incidence was approximately 5-fold higher than what was found for controls in the background population and 40% lower than for patients with recurrent ischemic stroke.
The pharmacology of TRP channels Holzer, Peter; Izzo, Angelo A
British journal of pharmacology,
20/May , Letnik:
171, Številka:
10
Journal Article
Recenzirano
Odprti dostop
This themed issue of the British Journal of Pharmacology contains review and research articles on recent advances in transient receptor potential (TRP) channel pharmacology. The review articles, ...written by a panel of distinguished experts, address the rapid progress in TRP channel research in fields as diverse as oncology, urology, dermatology, migraine, inflammation and pain. These reviews are complemented by original research reports focusing, among others, on the emerging roles of TRPV1 in osteoporosis and cystitis and on evodiamine as a lead structure for the development of potent TRPV1 agonists/desensitizers. Other papers highlight the differences in TRPV3 pharmacology between recombinant and native systems, the mechanisms of TRPM3 activation/inhibition and TRPP2 as a target of naringenin, a dietary flavonoid with anticancer actions. New therapeutic opportunities in pain may arise from the strategy to combine TRP channel and cell membrane impermeant sodium channel blockers to inhibit sensory nerve activity.
Linked Articles
This article is part of a themed section on the pharmacology of TRP channels. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue‐10
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