Strength Of Burst Research Articles

Mechanism of Coal Burst Triggered by Disturbing Mining-Induced Stress: An Experimental Investigation

The true triaxial test can accurately simulate the dynamic and static load superposition environment of deep mining and then reproduce the spatial and temporal evolution process of coal-rock dynamic disasters. This study used a self-developed true triaxial coal-rock dynamic behavior test system to investigate the dynamic failure characteristics and mechanism of coal bursts under different mining-induced stress disturbances. The results show that the perturbation duration of the coal samples under quasi-static load decreases with the increase of the disturbance rate, and the perturbation stress level increases first and then decreases. The coal samples can accumulate higher strain energy and show progressive and dynamic failure. The perturbation duration and stress peak of the coal sample under the cycle load decreased with the increase of the cycle amplitude and frequency, and the coal sample first spalled off on the free surface. The damage then developed internally until the coal burst. The perturbation duration and stress peak of coal samples decrease with the increase of transient stress and the perturbation stress levels. The dynamic failure process of coal samples is straightforward, and the strength of coal burst is violent and is more difficult to predict. The conclusions obtained help to deepen the understanding of the triggering mechanism of coal bursts.

Trends and Developments in the Detection of Pathogens in Central Nervous System Infections: A Bibliometric Study.

IntroductionRapid, sensitive, and specific laboratory assays are critical for the diagnosis and management of central nervous system (CNS) infections. The purpose of this study is to explore the intellectual landscape of research investigating methods for the detection of pathogens in patients with CNS infections and to identify the development trends and research frontier in this field.MethodsA bibliometric study is conducted by analyzing literature retrieved from the Web of Science (WoS) Core Collection Database for the years 2000 to 2021. CiteSpace software is used for bibliometric analysis and network visualization, including co-citation analysis of references, co-occurrence analysis of keywords, and cooperation network analysis of authors, institutions, and countries/regions.ResultsA total of 2,282 publications are eventually screened, with an upward trend in the number of publications per year. The majority of papers are attributed to the disciplines of MICROBIOLOGY, INFECTIOUS DISEASES, IMMUNOLOGY, NEUROSCIENCES & NEUROLOGY, and VIROLOGY. The co-citation analysis of references shows that recent research has focused on the largest cluster “metagenomic next-generation sequencing”; the results of the analysis of the highest-cited publications and the citation burst of publications reveal that there is a strong interest stimulated in metagenomic next-generation sequencing. The co-occurrence analysis of keywords indicates that “infection”, “pathogen”, “diagnosis”, “gene”, “virus”, “polymerase chain reaction”, “cerebrospinal fluid”, “epidemiology”, and “metagenomic next-generation sequencing” are the main research priorities in the field of pathogen detection for CNS infections, and the keyword with the highest strength of burst is “metagenomic next-generation sequencing”. Collaborative network analysis reveals that the USA, the Centers for Disease Control and Prevention of USA, and XIN WANG and JENNIFER DIEN BARD are the most influential country, institution, and researchers, respectively.ConclusionsExploring more advanced laboratory assays to improve the diagnostic accuracy of pathogens is essential for CNS infection research. Metagenomic next-generation sequencing is emerging as a novel useful unbiased approach for diagnosing infectious diseases of the CNS.

Scaling Relationship of In Vivo Muscle Contraction Strength of Rabbits Exposed to High-Frequency Nanosecond Pulse Bursts.

We studied the influence of various parameters of high-frequency nanosecond pulse bursts on the strength of rabbit muscle contractions. Ten unipolar high-frequency pulse bursts with various field intensities E (1 kV/cm, 4 kV/cm, and 8 kV/cm), intraburst frequencies f (10 kHz, 100 kHz, and 1 MHz), and intraburst pulse numbers N (1, 10, and 100) were applied using a pair of plate electrodes to the surface skin of the rabbits’ biceps femoris, and the acceleration signal of muscle contraction near the electrode was measured using a 3-axis acceleration sensor. A time- and frequency-domain analysis of the acceleration signals showed that the peak value of the signal increases with the increasing strength of the pulse burst and that the frequency spectra of the signals measured under various pulse bursts have characteristic frequencies (at approximately 2 Hz, 32 Hz, 45 Hz, and 55 Hz). Furthermore, we processed the data through multivariate nonlinear regression analysis and variance analysis and determined that the peak value of the signal scales with the logarithm to the base 10 of ENx, where x is a value that scales with the logarithm to the base 10 of intraburst frequency (f). These results indicate that for high-frequency nanosecond pulse treatment of solid tumors in or near muscles, when the field strength is relatively high, the intraburst frequency and the intraburst pulse number require appropriate selection to limit the strength of muscle contraction as much as possible.

MJO simulation in a cloud‐system‐resolving global ocean‐atmosphere coupled model

AbstractAn observed Madden‐Julian Oscillation (MJO) propagating from the central Indian Ocean to the western Pacific from 15 December 2006 to 10 January 2007 was successfully simulated by a cloud‐system‐resolving global ocean‐atmosphere coupled model without parameterization of cumulus convection. We found that the ocean coupling has significant impacts on the MJO simulation, e.g., strength of the moisture convergence, and the timing and strength of the westerly wind burst over the Maritime Continent. The model also generally well simulated the decay of the MJO in the western Pacific, as well as the changes in sea surface temperature. These results demonstrate that the cloud‐system‐resolving global ocean‐atmosphere coupled model can be used for realistic MJO simulation.

Mechanisms of coordination in distributed neural circuits: encoding coordinating information.

We describe synaptic connections through which information essential for encoding efference copies reaches two coordinating neurons in each of the microcircuits that controls limbs on abdominal segments of the crayfish, Pacifastacus leniusculus. In each microcircuit, these coordinating neurons fire bursts of spikes simultaneously with motor neurons. These bursts encode timing, duration, and strength of each motor burst. Using paired microelectrode recordings, we demonstrate that one class of nonspiking neurons in each microcircuit's pattern-generating kernel--IPS--directly inhibits the ASCE coordinating neuron that copies each burst in power-stroke (PS) motor neurons. This inhibitory synapse parallels IPS's inhibition of the same PS motor neurons. Using a disynaptic pathway to control its membrane potential, we demonstrate that a second type of nonspiking interneuron in the pattern-generating kernel--IRSh--inhibits the DSC coordinating neuron that copies each burst in return-stroke (RS) motor neurons. This inhibitory synapse parallels IRS's inhibition of the microcircuit's RS motor neurons. Experimental changes in the membrane potential of one IPS or one IRSh neuron simultaneously changed the strengths of motor bursts, durations, numbers of spikes, and spike frequency in the simultaneous ASCE and DSC bursts. ASCE and DSC coordinating neurons link the segmentally distributed microcircuits into a coordinated system that oscillates with the same period and with stable phase differences. The inhibitory synapses from different pattern-generating neurons that parallel their inhibition of different sets of motor neurons enable ASCE and DSC to encode details of each oscillation that are necessary for stable, adaptive synchronization of the system.

Analysis of Burst and Collapse Strength for Tubular with Wearing Defects

Taking account of the influence of friction between the outer wall of buckling tubular and the inner wall of casing under vibrating loads, the burst and collapse strengths of worn tubular would be reduced greatly compared to the unworn tubular. If the reduction of burst and collapse strength weren’t taken into consideration, there may be potential risk in well completion. The models of worn tubular strings were established based on finite element method, and thus the relationships between strength of burst and collapse and the degree of wear were analyzed. The results of FEM were verified by the equations in API 5C3. The results show that the strengths of burst and collapse will be reduced with the increase of wear degree, and the burst strength will be reduced more sharply. When the tubular strings are worn by 30%, the strengths of burst and collapse will be reduced by almost 50%. While the strengths of burst and collapse will be reduced by almost 60%, when the tubular strings are worn by 50%. So, to avoid the accident caused by the worn tubular, the work case should be controlled strictly correspondingly.

Baroreflex and Muscle Metaboreflex

During heavy exercise, the arterial baroreflex and the reflexes evoked by the activation of those afferent nerve endings in the working skeletal muscles that are sensitive to metabolic changes (the so-called muscle metaboreflex) are hypothesized to be activated and, moreover, to interact in ways that lead to the modulation of the primary cardiovascular reflex responses. For the past few years, our group has been investigating the interaction between the arterial baroreflex and the muscle metaboreflex. We have focused our efforts in identifying the effects of muscle metaboreflex activation on the arterial baroreflex regulation of the cardiovascular hemodynamics and muscle sympathetic nerve activity (MSNA) in humans. In a series of studies, we have found that during muscle metaboreflex activation, dynamic carotid baroreflex responses are modulated, as exemplified by the augmentation of the MSNA, leg vascular conductance and blood pressure responses to carotid baroreflex unloading and the shorter suppression period of MSNA, diminished vasodilation, and reduced blood pressure response to carotid baroreflex stimulation. Furthermore, we have found that the modification of the arterial baroreflex-mediated beat-to-beat control of MSNA, which is seen during activation of the muscle metaboreflex (i.e., resetting and an increase in sensitivity), could be a consequence of the alteration in the arterial baroreflex control of both the occurrence and strength of the MSNA burst. In addition, we have demonstrated that the arterial baroreflex beat-to-beat control of MSNA is time-dependently modulated during isometric exercise. We suggest that the modulation of arterial baroreflex function during the activation of muscle metaboreflex is one of the mechanisms for increasing, or maintaining, blood pressure at the required pressure and thereby contributes to the regulation of the cardiovascular system during exercise.

Bursty stellar populations and obscured active galactic nuclei in galaxy bulges

We investigate trends between the recent star formation history and black hole growth in galaxy bulges in the Sloan Digital Sky Survey. The galaxies lie at 0.01 < z < 0.07 where the fibre aperture covers only the central 0.6–4.0 kpc diameter of the galaxy. We find strong trends between black hole growth, as measured by dust-attenuation-corrected [O iii] luminosity, and the recent star formation history of the bulges. 56 per cent of the bulges are quiescent with no signs of recent or ongoing star formation and, while almost half of all active galactic nuclei (AGN) lie within these bulges, they contribute only ∼10 per cent to the total black hole growth in the local Universe. At the other extreme, the AGN contained within the ∼4 per cent of galaxy bulges that are undergoing or have recently undergone the strongest starbursts, contribute at least 10–20 per cent of the total black hole growth. Much of this growth occurs in AGN with high amounts of dust extinction and thus the precise numbers remain uncertain. The remainder of the black hole growth (>60 per cent) is contributed by bulges with more moderate recent or ongoing star formation. The strongest accreting black holes reside in bulges with a wide range in recent star formation history. We conclude that our results support the popular hypothesis for black hole growth occurring through gas inflow into the central regions of galaxies, followed by a starburst and triggering of the AGN. However, while this is a significant pathway for the growth of black holes, it is not the dominant one in the present-day Universe. More unspectacular processes are apparently responsible for the majority of this growth. In order to arrive at these conclusions we have developed a set of new high signal-to-noise ratio (S/N) optical spectral indicators, designed to allow a detailed study of stellar populations which have undergone recent enhanced star formation. Working in the rest-frame wavelength range 3750–4150 Å, ideally suited to many recent and ongoing spectroscopic surveys at low and high redshift, the first two indices are equivalent to the previously well-studied 4000-Å break strength and Hδ equivalent width. The primary advantage of this new method is a greatly improved S/N for the latter index, allowing the present study to use spectra with S/N per pixel as low as 8. The third index measures the excess strength of Ca ii (H&K), which is particularly sensitive to the transition of a post-starburst spectrum from A to F stars, and allows the degeneracy between time of burst and strength of burst to be broken.

Bursts of Information: Coordinating Interneurons Encode Multiple Parameters of a Periodic Motor Pattern

The limbs on different segments of the crayfish abdomen that drive forward swimming are directly controlled by modular pattern-generating circuits. These circuits are linked together by axons of identified coordinating interneurons. We described the distributions of these neurons in each abdominal ganglion and monitored their firing during expression of the swimming motor pattern. We analyzed the timing, the numbers of spikes, and the duration of each burst of spikes in these coordinating neurons. To see what information these neurons encoded, we correlated these parameters with the timing, durations, and strengths of bursts of spikes in motor axons from the same modules. During the power-stroke phase of each output cycle, the anterior-projecting neurons fired bursts of spikes that encoded information about the start-time, duration, and strength of each burst of spikes in power-stroke motor neurons from the same module. When the period and intensity of the motor output fluctuated, the bursts of spikes in these neurons tracked these fluctuations accurately. Each additional spike in these neurons signified an increase in the strength of the power-stroke burst. The posterior-projecting neurons that fired during the return-stroke phase encoded similar information about the return-stroke motor neurons. Although homologous neurons from different ganglia were qualitatively similar, neurons from posterior ganglia fired significantly more spikes per burst than those from more anterior ganglia, a segmental gradient that correlates with the normal posterior-to-anterior phase progression of limb movements. We propose that this gradient and a similar gradient in the durations of bursts in power-stroke motor neurons might reflect a hitherto-undetected difference in the excitation or intrinsic excitability of swimmeret modules in different segments.

An Improved Framework for Superparameterization

This paper discusses a large-scale modeling system with explicit representation of small-scale and mesoscale processes provided by a cloud-resolving model embedded in each column of a large-scale model, the superparameterization. In the original formulation, referred to as the cloud-resolving convection parameterization (CRCP), thermodynamic variables were coupled using appropriate averaging procedure, but horizontal momenta were coupled only through the relaxation approach. The improved system is based on the general formulation of the coupling between the two models, and the relaxation technique is abandoned. A simple but robust time integration scheme for the system is developed using the nonoscillatory forward-in-time approach applied in both the large-scale and cloud-scale models. The improved formulation is applied to the problem, previously studied by the author, of large-scale organization of equatorial convection on a rotating constant sea surface temperature (SST) aquaplanet in convective– radiative quasi equilibrium. Three simulations are performed using 2D small-scale models as in the original CRCP approach. In the first two simulations, the 2D models have zonal orientation. The first simulation applies the new coupling scheme in the physical setup, which does not include surface drag. Tight coupling between large-scale and small-scale horizontal momenta results in rapid organization of Madden–Julian oscillation (MJO)-like coherent structures and development of strong superrotation. In the second simulation, surface drag is added into 2D small-scale model physics. This results in the development of MJO-like coherent structures with weak superrotation and more realistic strength of the westerly wind burst when compared to the terrestrial MJO. Surface drag is also included in the third simulation, where the coupling is formulated in such a way that orientation of 2D small-scale model domains is along the lower-tropospheric winds and thus it varies in space and time. Results from the third simulation are qualitatively similar to the simulation with surface drag and zonal orientation of small-scale models.

EXOSAT observations of 4U/MXB 1636-53 - On the relation between the amount of accreted fuel and the strength of an X-ray burst

During Exosat observations of 4U/MXB 1636-53 in August 1985, three bursts were observed in 6 h and 24 bursts in 79 h of uninterrupted observation. The burst times, burst fluences, peak burst fluxes, burst rise times, decay times, burst intervals, mean persistent fluxes, and the product of the latter two are listed, analyzed, and discussed. The implications of the results for thermonuclear flash models are examined. A model which fits the data well involves bursts which suffer from nuclear energy losses due to stable hydrogen burning between bursts. Thus, the percentage of 'lost' energy increases with increasing burst intervals. For individual bursts, however, there are significant deviations from the approximate linear relationship.

Solar soft X-rays and solar activity

Flare-associated soft X-ray bursts (8–12 A) are examined for 283 events observed by OSO-III. These bursts are shown to be predominantly thermal in nature. Their time-profiles are roughly similar to those of the associated Hα flares, although the X-ray burst begins about two minutes earlier, on the average. The strength of the soft X-ray burst is directly related to the area and brilliance of the flare, the age and ‘flare-richness’ of the associated plage, and the general level of solar activity at the time of the burst. The peak enhancements in the soft X-ray and Hα emission rates during flares are of the same order of magnitude, as are the total flare energies radiated at these wavelengths. We estimate that soft X-radiation accounts for up to 10% of a flare's total electromagnetic emission.