Self-learning active noise control Yuan, J
The Journal of the Acoustical Society of America,
10/2008, Volume:
124, Issue:
4
Journal Article
Peer reviewed
Open access
An important step for active noise control (ANC) systems to be practical is to develop model independent ANC (MIANC) systems that tolerate parameter variations in sound fields. Reliabilities and ...stabilities of many MIANC systems depend on results of online system identifications. Parameter errors due to system identifications may threaten closed-loop stabilities of MIANC systems. A self-learning active noise control (SLANC) system is proposed in this study to stabilize and optimize an ANC system in case identified parameters are unreliable. The proposed system uses an objective function to check closed-loop stability. If partial or full value of the objective function exceeds a conservatively preset threshold, a stability threat is detected and the SLANC system will stabilize and optimize the controller without using parameters of sound fields. If the reference signal is available, the SLANC system can be combined with a feedforward controller to generate both destructive interference and active damping in sound fields. The self-learning method is simple and stable for many feedback ANC systems to deal with a worst case discussed in this study.
Biochar was prepared using a low temperature pyrolysis method from nine plant materials including non-leguminous straw from canola, wheat, corn, rice and rice hull and leguminous straw from soybean, ...peanut, faba bean and mung bean. Soil pH increased during incubation of the soil with all nine biochar samples added at 10 g/kg. The biochar from legume materials resulted in greater increases in soil pH than from non-legume materials. The addition of biochar also increased exchangeable base cations, effective cation exchange capacity, and base saturation, whereas soil exchangeable Al and exchangeable acidity decreased as expected. The liming effects of the biochar samples on soil acidity correlated with alkalinity with a close linear correlation between soil pH and biochar alkalinity (R² = 0.95). Therefore, biochar alkalinity is a key factor in controlling the liming effect on acid soils. The incorporation of biochar from crop residues, especially from leguminous plants, can both correct soil acidity and improve soil fertility.
The demonstration of protein sequence and functional homology of the Caenorhabditis elegans programmed cell death gene product, CED-3, with human caspase-1 in 1993 triggered an explosion of research ...activities toward the understanding of molecular mechanisms of apoptosis. During the past 15 years, a plethora of knowledge has been obtained on the mammalian caspases, the homologs of CED-3, with regard to their distinct physiological functions, their substrates, different activation mechanisms, the signal transduction pathways that lead to their activation as well as their involvement in the pathogenesis of diseases. Such knowledge is beginning to be translated into new therapies for the treatment of human diseases.
Fast radio bursts (FRBs) are millisecond-duration radio transients
of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star ...magnetospheres
or relativistic shocks far from the central energy source
. Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters
or variable polarization angles in some other apparently one-off events
. Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks.
To evaluate a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and compare it with RT-PCR.
...We designed primers specific to the orf1ab and S genes of SARS-CoV-2. Total viral RNA was extracted using the QIAamp Viral RNA Mini Kit. We optimized the RT-LAMP assay, and evaluated it for its sensitivity and specificity of detection using real-time turbidity monitoring and visual observation.
The primer sets orf1ab-4 and S-123 amplified the genes in the shortest times, the mean (±SD) times were 18 ± 1.32 min and 20 ± 1.80 min, respectively, and 63°C was the optimum reaction temperature. The sensitivities were 2 × 101 copies and 2 × 102 copies per reaction with primer sets orf1ab-4 and S-123, respectively. This assay showed no cross-reactivity with 60 other respiratory pathogens. To describe the availability of this method in clinical diagnosis, we collected 130 specimens from patients with clinically suspected SARS-CoV-2 infection. Among them, 58 were confirmed to be positive and 72 were negative by RT-LAMP. The sensitivity was 100% (95% CI 92.3%–100%), specificity 100% (95% CI 93.7%–100%). This assay detected SARS-CoV-2 in a mean (±SD) time of 26.28 ± 4.48 min and the results can be identified with visual observation.
These results demonstrate that we developed a rapid, simple, specific and sensitive RT-LAMP assay for SARS-CoV-2 detection among clinical samples. It will be a powerful tool for SARS-CoV-2 identification, and for monitoring suspected patients, close contacts and high-risk groups.
The strong spectral dependence of light absorption of brown carbon (BrC) aerosol is regarded to influence aerosol's radiative forcing significantly. The Absorption Angstrom Exponent (AAE) method has ...been widely used in previous studies to attribute light absorption of BrC at shorter wavelengths for ambient aerosols, with a theoretical assumption that the AAE of "pure" black carbon (BC) aerosol equals to 1.0. In this study, the AAE method was applied to both urban and rural environments in the Pearl River Delta (PRD) region of China, with an improvement of constraining the realistic AAE of "pure" BC through statistical analysis of on-line measurement data. A three-wavelength photo-acoustic soot spectrometer (PASS-3) and aerosol mass spectrometers (AMS) were used to explore the relationship between the measured AAE and the relative abundance of organic aerosol to BC. The regression and extrapolation analysis revealed that more realistic AAE values for "pure" BC aerosol (AAEBC) were 0.86, 0.82, and 1.02 between 405 and 781 nm, and 0.70, 0.71, and 0.86 between 532 and 781 nm, in the campaigns of urbanwinter, urbanfall, and ruralfall, respectively. Roadway tunnel experiments were conducted and the results further confirmed the representativeness of the obtained AAEBC values for the urban environment. Finally, the average light absorption contributions of BrC ( relative uncertainties) at 405 nm were quantified to be 11.7 % ( 5 %), 6.3 % ( 4 %), and 12.1 % ( 7 %) in the campaigns of urbanwinter, urbanfall, and ruralfall, respectively, and those at 532 nm were 10.0 % ( 2 %), 4.1 % ( 3 %), and 5.5 % ( 5 %), respectively. The relatively higher BrC absorption contribution at 405 nm in the ruralfall campaign could be reasonably attributed to the biomass burning events nearby, which was then directly supported by the biomass burning simulation experiments performed in this study. This paper indicates that the BrC contribution to total aerosol light absorption at shorter wavelengths is not negligible in the highly urbanized and industrialized PRD region.
BACKGROUND:Angiotensin-converting enzyme 2 (ACE2) converts angiotensin II, a potent vasoconstrictor, to angiotensin-(1–7) and is also a membrane protein that enables coronavirus disease 2019 ...(COVID-19) infectivity. AMP-activated protein kinase (AMPK) phosphorylation of ACE2 enhances ACE2 stability. This mode of posttranslational modification of ACE2 in vascular endothelial cells is causative of a pulmonary hypertension (PH)–protective phenotype. The oncoprotein MDM2 (murine double minute 2) is an E3 ligase that ubiquitinates its substrates to cause their degradation. In this study, we investigated whether MDM2 is involved in the posttranslational modification of ACE2 through its ubiquitination of ACE2, and whether an AMPK and MDM2 crosstalk regulates the pathogenesis of PH.
METHODS:Bioinformatic analyses were used to explore E3 ligase that ubiquitinates ACE2. Cultured endothelial cells, mouse models, and specimens from patients with idiopathic pulmonary arterial hypertension were used to investigate the crosstalk between AMPK and MDM2 in regulating ACE2 phosphorylation and ubiquitination in the context of PH.
RESULTS:Levels of MDM2 were increased and those of ACE2 decreased in lung tissues or pulmonary arterial endothelial cells from patients with idiopathic pulmonary arterial hypertension and rodent models of experimental PH. MDM2 inhibition by JNJ-165 reversed the SU5416/hypoxia-induced PH in C57BL/6 mice. ACE2-S680L mice (dephosphorylation at S680) showed PH susceptibility, and ectopic expression of ACE2-S680L/K788R (deubiquitination at K788) reduced experimental PH. Moreover, ACE2-K788R overexpression in mice with endothelial cell–specific AMPKα2 knockout mitigated PH.
CONCLUSIONS:Maladapted posttranslational modification (phosphorylation and ubiquitination) of ACE2 at Ser-680 and Lys-788 is involved in the pathogenesis of pulmonary arterial hypertension and experimental PH. Thus, a combined intervention of AMPK and MDM2 in the pulmonary endothelium might be therapeutically effective in PH treatment.
Exploitation of the intrinsic electrical properties of particles has recently emerged as an appealing approach for trapping and separating various scaled particles. Initiative particle manipulation ...by dielectrophoresis (DEP) showed remarkable advantages including high speed, ease of handling, high precision and being label-free. Herein, we provide a general overview of the manipulation of polystyrene (PS) beads and related particles
via
DEP; especially, the wide applications of these manipulated PS beads in the quantitative evaluation of device performance for model validation and standardization have been discussed. The motion and polarizability of the PS beads induced by DEP were analyzed and classified into two categories as positive and negative DEP within the time and space domains. The DEP techniques used for bioparticle manipulation were demonstrated, and their applications were conducted in four fields: trapping of single-sized PS beads, separation of multiple-sized PS beads by size, separation of PS beads and non-bioparticles, and separation of PS beads and bioparticles. Finally, future perspectives on DEP-on-a-chip have been proposed to discriminate bio-targets in the network of microfluidic channels.
Exploitation of the intrinsic electrical properties of particles has recently emerged as an appealing approach for trapping and separating various scaled particles.
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