A new error correction method for the stationary Navier-Stokes equations based on two local Gauss integrations

summary:A new error correction method for the stationary Navier-Stokes equations based on two local Gauss integrations is presented. Applying the orthogonal projection technique, we introduce two local Gauss integrations as a stabilizing term in the error correction method, and derive a new error correction method. In both the coarse solution computation step and the error computation step, a locally stabilizing term based on two local Gauss integrations is introduced. The stability and convergence of the new error correction algorithm are established. Numerical examples are also presented to verify the theoretical analysis and demonstrate the efficiency of the proposed method

Research on the representation of granular vertical size grading and numerical simulation method with the typical waste rock site

Gradiranje zrnatog materijala po vertikali, kao tipično obilježje visokog odlagališta jalovine s jednim nasipom, važan je čimbenik koji utječe na stabilnost padine odlagališta jalovine. Na bazi terenskog istraživanja raspodjele veličine zrnatog materijala tipičnog odlagališta jalovine, primjenom Cellular Automaton metode razvili smo HHC-Granular model za opis pojave gradiranja po vertikali. Što više, konstruiran je model padine, a za gradiranje veličine upotrebljen je Flac3D softver na temelju podataka prikupljenih na tipičnom odlagalištu jalovine. Stabilnost padine kod različitih načina odlaganja analizirala se primjenom konstruiranog modela padine. Rezultati su pokazali da su se na gornjoj platformi odlagališta pojavile pukotine zbog naprezanja, a klizište postojeće padine nastalo je u sredini odlagališta jalovine. Stanje postojeće padine bilo je privremeno stabilno. Za potpuno prekrivanje odlagališta s više nasipa, vektor premještanja računalnih slika pokazao je da je na vrhu odlagališta jalovine uleknuće, a na dnu se pojavila horizontalna distorzija. Do puknuća padine može doći ako se na gornjoj platformi odlagališta pojave napukline, a na dnu klizanje luka. Kad su se razmotrile karakteristike čvrstoće zrnatog materijala kao jedini faktor u analizi stabilnosti padine, gradiranje veličine zrnatog materijala po vertikali pomoglo je u stabilnosti odlagališta jalovine.The vertical size grading of granular, as a typical characteristic with the high single-bench waste rock site, is an important factor affecting the slope stability of waste rock site. On the basis of field investigation of granular size distribution with the typical waste rock site, we used the Cellular Automaton method to develop the HHC-Granular model which could describe the phenomenon of apparent vertical size grading. Moreover, the slope model was constructed and size grading was considered with the aid of Flac3D software based on the data collected from the typical waste rock site. The slope stability of various piling up patterns had been analyzed using the constructed slope model. The results indicated that at the top platform of waste rock site appeared the obvious tension cracks and slippage position of present slope was in the middle of waste rock site. The present slope was in the stage of temporarily steady. To adopt full overlay dump of multi-bench, the displacement vector of calculation images showed that the top of waste rock site was the subsidence and the horizontal distortion appeared at its bottom. The slope failure mode was that at the top platform of waste rock site appeared the cracks and its bottom showed the arc slippage. When the strength characteristics of granular were considered as the only factor in the slope stability analysis, the vertical size grading of high-bench waste rock site was helpful to slope stability

Case report: Primary pericardial angiosarcoma, a rare cause of cardiac tamponade

Primary pericardial angiosarcoma is a rare malignancy of the pericardium with variable clinical features and imaging characteristics. Herein, we report a case of histopathologically confirmed pericardial angiosarcoma in a 66-year-old man. The patient developed cardiac tamponade in a short time period. The transthoracic echocardiography showed the presence of multiple irregular echodensities, heterogeneous in echogenicity, encasing the apex of both ventricles in the pericardial space, initially misinterpreted as pericardial effusion. The patient died of cardiogenic shock despite undergoing a surgical pericardiectomy. Pericardial angiosarcoma can manifest as a mass obliterating the pericardial sac, rather than the typical pericardial effusion observed on echocardiography. Multimodality imaging studies aid in diagnosing primary pericardial angiosarcoma, but the final diagnosis relies on tissue histopathology

Study on tailings dam over-topping failure model test and break mechanism under the rainfall condition

Na temelju samo-konstruiranog uređaja za eksperimentiranje simulacijom prekida jalovinskog nasipa, eksperimentalna studija oštećenja nasipa provedena je u kišnim uvjetima. Zakonitost promjene linije infiltracije, proces razvoja tijela nasipa, mehanizam oštećenja nasipa i pomicanje nasipa nakon kolapsa dobiveni su pomoću uređaja za oborine, uređaja za mjerenje infiltracijske linije, uređaja za praćenje pomaka, kamere itd. Rezultati pokazuju sljedeće: u ranoj fazi kiše, promjena linije infiltracije u prednjem umjetnom jezeru i vanjskoj padini nasipa očito je zaostajala za razinom vode, a u sredini i kraju umjetnog jezera to nije uočeno. U kasnijoj fazi kiše, fenomen zaostajanja postupno nestaje, a promjena razine vode ima očiti učinak na promjenu linije infiltracije. U ranoj fazi oštećenja nasipa, curenje i preljev vode dogodili su se na vanjskoj padini nasipa, a došlo je do lokalnog kolapsa. U kasnijim fazama prekida jalovinskog nasipa voda protječe preko nasipa i nastavlja erodirati tijelo nasipa, što dovodi do zatajenja nasipa. Pod djelovanjem propusne sile pojavljuje se fenomen cjevovoda u nasipu. S kontinuiranom erozijom protoka vode, povećana je propusna sila, plutajuća jaka snaga uzgona i tlak vode pora, protu-otpor je oslabio i smanjena je stabilnost nasipa. Nakon oštećenja tijela nasipa, najveće je pomicanje zemlje u proboju, pored proboja, pomicanje zemlje uglavnom se događa kod potpore nasipa. Vanjska ekspanzija uglavnom se javlja u sredini nasipa i podnožju nasipa. Rezultati istraživanja pružaju neke smjernice i referentnu vrijednost za analizu modela i mehanizma prekida jalovinskog nasipa i sprječavanje katastrofe te kontrole pod kišnim uvjetima.Based on self-designed tailings dam simulation experiment device of tailings dam-break, experimental study of tailings dam failure was carried out under the condition of rainfall. The change rule of infiltration line, the developing process, the mechanism of dam failure and the displacement of the dam body after collapse were obtained and recorded by the rainfall devices, the infiltration line measuring devices, the displacement monitoring devices and the camera. The results are as follows: in the early stage of rainfall, the changes of the infiltration line in the front reservoir and the outside slope of the dam were obviously lagging behind the water level, but in the middle and tail of the reservoir it was not obvious. In the later stage of the rainfall, the lagging phenomenon gradually disappeared, and the change of water level had an obvious effect on the change of infiltration line. At the early stage of the dam failure, seepage and water overflow occurred on the outer slope of the tailings dam, causing local collapse to occur. In the late stages of dam break, the water flew over the dam crest and continued to erode the dam body, thus lead to the dam failure. Under the action of seepage force, the phenomenon of piping occurred in the dam. With the continuous erosion of water flow, the seepage force, floating severe, buoyancy force and pore water pressure were increased, the anti-resistance was weakened and the stability of dam was reduced. After the dam failed, the settlement displacement in the breach was the largest, in addition to the breach, the settlement displacement occurred mainly at the dam abutment. The external expansion occurred mainly in the middle dam and dam foot. The research results provide some valuable guidance and reference for the mechanism analysis of the tailings dam-break, the disaster prevention and controlling when subjected to rainfall

Global myocardial work parameters measured by the index beat method are comparable to the average of 10 beats in patients during atrial fibrillation

IntroductionEvaluation of left ventricular (LV) global systolic function is clinically important for patients with atrial fibrillation (AF); however, the rhythm irregularity inherent to AF poses challenges for assessing novel LV systolic function parameters, such as global myocardial work (MW). This study aimed to validate the feasibility of using the single index beat method to quantify LV MW during echocardiography in patients with AF, compared with the traditional 10-beat average method.MethodsA prospective study was performed in 120 patients with AF at the time of the index echocardiography. Global longitudinal strain was assessed using speckle tracking echocardiography from a triplane dataset, followed by MW analysis to calculate global myocardial work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). A total of 10 consecutive beats were evaluated, with both the average value and the maximal difference among the 10 beats recorded. The index beat was defined as on in which the ratio of the preceding to the pre-preceding R-R interval was approximately 1 (0.96–1.04). MW parameters from the index beat were extracted for analysis. Inter-method consistency was assessed using the intra-class correlation coefficient (ICC) with a single-rater, absolute agreement, two-way random effects model. Inter- and intra-observer reproducibility was also assessed.ResultsGlobal MW derived from the index beat was comparable with the average of 10 beats: GWI, 1,157.19 ± 416.83 vs. 1,188.98 ± 452.96 mmHg% (p < 0.05); GCW, 1,721.46 ± 524.69 vs. 1,732.46 ± 524.24 mmHg% (p > 0.05); GWW, 237.95 (183.60) vs. 207.50 (207.25) mmHg% (p < 0.001); and GWE, 85.80% (11.05) vs. 86.50% (12.75) (p < 0.001). Consistency analysis showed that ICCs for all assessed MW parameters were >0.87. Satisfactory inter- and intra-observer reproducibility of the measurements by the index beat method was also found.ConclusionsGlobal MW measured using the index beat method demonstrated good agreement with the average over 10 beats in patients with AF, supporting its reliability as a surrogate for the traditional method in clinical practice

Searching for the highest energy of pulsation and critical luminosity of Swift J0243.6+6124 observed by Insight-HXMT

Owing to the broad energy coverage of Insight-HXMT in the hard X-ray band, we detected the highest energy of pulsation exceeding 200 keV around the 2017-2018 outburst peak of the first Galactic pulsating ultraluminous X-ray source (PULX) Swift J0243.6+6124, which is the highest energy detected from PULXs to date. We also obtained the highest energy of pulsation of every exposure during the outburst in 2017-2018, and found the highest energy is roughly positively correlated with luminosity. Using our newly developed method, we identified the critical luminosity being $4\times 10^{38}\, \rm erg\,s^{-1}$ when the main peaks of the low and high energy pulse profiles became aligned, which separates the fan-beam dominated and pencil-beam dominated accretion regimes. Above the critical luminosity, the phase of the main peak shifted gradually from 0.5 to 0.8 until the outburst peak in all energy bands is reached, which is in agreement with the phase shift found previously at low energies. Our result is consistent with what is derived from spectral analysis.Comment: 9 pages, 9 figures, published in RA

The Yin-Yang Property of Chinese Medicinal Herbs Relates to Chemical Composition but Not Anti-Oxidative Activity: An Illustration Using Spleen-Meridian Herbs

“Yin-Yang” and “Five Elements” theories are the basis theories of Traditional Chinese Medicine (TCM). To probe and clarify the theoretical basis of these ancient Chinese wisdoms, extensive efforts have been taken, however, without a full success. In the classification of TCM herbs, hot, cold and neutral herbs are believed to possess distinct profile of chemical compositions of which the compounds should have different polarity and mass: this view provides a new perspective for further illustration. To understand the chemical properties of TCMs in the classification of “Yin-Yang” and “Five Elements,” 15 commonly used herbs attributed to spleen-meridian were selected for analyses. Chemically standardized water extracts, 50% ethanol extracts and 90% ethanol extracts were prepared and subjected to different analytic measurements. Principle component analysis (PCA) of full spectrum of HPLC, NMR and LC-MS of the extracts were established. The results revealed that the LC-MS profile showed a strong correlation with the “Yin-Yang” classification criterion. The Yang-stimulating herbs generally contain more compounds with lower molecular weight and less polar property. Additionally, a comprehensive anti-oxidative profiles of selected herbs were developed, and the results showed that its correlation with cold and hot properties of TCM, however, was rather low. Taken together, the “Yin-Yang” nature of TCM is closely related to the physical properties of the ingredients, such as polarity and molecular mass; while such classification has little correlation with anti-oxidative property. Therefore, the present results provide a new direction in probing the basic principle of TCM classification

African regional and national burden of diabetes mellitus and its attributable risk factors from 1990 to 2021: results from the global burden of disease study 2021

AimsDiabetes mellitus (DM), a chronic disease characterized by hyperglycemia, has become a global health concern. This study evaluates the burden of DM in the African region from 1990–2021 to inform prevention and control strategies.MethodsUtilizing data from the Global Burden of Disease (GBD) 2021, we analyzed the incidence, prevalence, mortality, disability-adjusted life years, age-standardized rates and estimated annual percentage changes of DM, type 1 DM (T1DM) and type 2 DM (T2DM) in the African region. Decomposition analysis was utilized to explore the contributions of population growth, aging and epidemiological changes to the disease burden. The comparative risk assessment framework was employed to estimate the influence of second-level risk factors on the diabetes burden.ResultsFrom 1990 to 2021, the disease burden of DM, T1DM and T2DM in the African region increased significantly. The age-standardized incidence rate of DM, T1DM and T2DM increased from 157.284, 5.934 and 151.350 per 100,000 population in 1990 to 250.459, 5.987 and 244.472 per 100,000 population in 2021, respectively. The age-standardized prevalence rate for DM, T1DM and T2DM increased from 2,426.585, 185.366 and 2,241.219 per 100,000 population in 1990 to 4,677.459, 189.384 and 4,488.075 per 100,000 population in 2021. The age-standardized mortality rate for DM and T2DM increased from 39.568 and 38.649 per 100,000 population in 1990 to 44.860 and 44.193 per 100,000 population in 2021. The age-standardized disability-adjusted life years(DALYs)for DM and T2DM increased from 1,123.079 and 1,059.430 per 100,000 population in 1990 to 1,379.240 and 1,329.440 per 100,000 population in 2021. Population growth was identified as the key driver of the increasing disease burden. High body mass index was a major risk factor for DALYs in DM/T2DM. Suboptimal temperature was a major risk factor for DALYs in T1DM. Mauritius had the highest incidence and prevalence rates for DM, T1DM and T2DM, while Kenya and Niger exhibited the lowest rates for DM/T2DM and T1DM, respectively.ConclusionDiabetes mellitus (DM) imposes a substantial global disease burden across Africa, necessitating urgent public health interventions to address risk factors and enhance prevention and control measures

Dynamic change in maternal cardiac function during pregnancy

BackgroundPregnant women experience various physiological changes that, if uncompensated, may result in varying degrees of cardiac dysfunction, and adverse pregnancy outcomes. Left ventricular (LV) global longitudinal strain (GLS) and P-wave to A' duration on tissue Doppler imaging (PA-TDI) have been shown to be able to detect subtle cardiac dysfunction.MethodsThe present study was a prospective cross-sectional study. A total of 506 healthy pregnant women were enrolled, including 149 during early pregnancy (before 13 weeks' gestation, T1 group), 99 during mid-pregnancy (14–27 weeks' gestation, T2 group), and 258 during late pregnancy (after 28 weeks' gestation, T3 group), while 172 age- and baseline weight-matched healthy nonpregnant women served as the control group (NPC group). Clinical and echocardiographic data of the subjects were collected. The difference in cardiac structure and function among the 4 groups were analyzed. Multivariate regression analysis was conducted to identify the independent factors influencing change in cardiac function.ResultsThe median age of the 4 groups were comparable [T1 group, 31.0 (28.5,34.0) years; T2 group, 31.0 (29.0,34.0) years; T3 group, 31.0 (29.0,34.0) years; the NPC group, 31.0 (28.0,34.0) years, P = 0.905). Left ventricular ejection fraction (LVEF) during late pregnancy was lower than that during early pregnancy and the control group, but remained within normal range. With the increase of gestational age, the absolute value of LV-GLS decreased gradually [T1 group, −19.00 (−21.40, −16.70); T2 group, −17.40 (−20.10, −15.30); T3 group, −16.35 (−17.93, −13.97); P < 0.001]. PA-TDI during the third trimester was longer than that in the first [117.65 (108.45,128.03) ms vs. 114.19 (105.61,121.11) ms, P = 0.012] or the second trimester [111.32 (107.27,121.11) ms, P = 0.010]]. Multivariate regression analysis showed that gestational age was independently associated with LV-GLS (b = 0.096, t = 2.212, P = 0.027) and PA-TDI (b = 0.158, t = 2.449, P = 0.014).ConclusionPregnant women show a trend toward decreased left ventricular systolic and diastolic function. PA-TDI and LV-GLS can be used to evaluate subtle change in left cardiac function in pregnant women