Regular Flow Research Articles

Legionella in Primary School Hot Water Systems from Two Municipalities in the Danish Capital Region.

Legionella contamination in public water systems poses significant health risks, particularly in schools where vulnerable populations, including children, regularly use these facilities. This study investigates the presence of Legionella in the hot water systems from 49 primary schools across two municipalities in the Danish capital region. Water samples were collected from taps in each school, and both first-flush and stabile temperature samples were analysed for Legionella contents. The findings revealed that 97% of schools in Municipality 1 and 100% in Municipality 2 had Legionella in their hot water systems. The content of Legionella colonies was significantly higher in schools in Municipality 1, which was probably because of overall lower water temperatures. At stabile temperatures, 76% and 50% of the schools in the two municipalities exceeded the European Union's recommended limit of 1000 CFU/L. Stabile peripheral water temperatures were achieved after 3 min. Tap water temperatures above 54 °C and central tank temperatures above 59 °C were associated with Legionella contents below 1000 CFU/L. This study highlights the need for more stringent Legionella control procedures in schools, including higher water temperatures and refining Legionella reducing interventions with the addition of regular flow and draining procedures.

Allogenic MSC infusion in kidney transplantation recipients promotes within 4 hours distinct B cell and T cell phenotypes.

Infusion of mesenchymal stromal cells (MSCs) has been proposed as immune-modulatory therapy in solid organ transplantation. The use of allogenic MSCs could improve standardization and allow for direct availability of the product. The nonrandomized phase Ib Neptune clinical trial provided safety and feasibility data on the use of allogenic bone-marrow-derived MSCs, infused in 10 patients at week 25 and 26 post kidney transplantation. Here, we performed detailed analysis on the peripheral blood immune cell composition of these patients up to 52 weeks post transplantation. We used a 40 marker antibody panel with mass cytometry to assess potential effects of MSC therapy on the immune system. We showed minor changes in major immune lineages at week 27, 34 and 52 post kidney transplantation after MSC infusion at week 25 and week 26, confirming previous data with regular flow cytometry. However, in a direct comparison between pre- and post MSC infusion, as soon as 4 hours after MSC infusion, we observed a significant increase in cell numbers of B cell and T cell subsets that shared a unique expression of CD11b, CD11c, CD38, CD39, and Ki-67. Exploring these CD11b+CD11c+CD38+CD39+Ki-67+ B cells and T cells in the context of MSC infusion after kidney transplantation may be a promising avenue to better understand the immunological effects of MSC therapy.

Theoretical predictions to facilitate the method development in slalom chromatography for the separation of large DNA molecules

Slalom chromatography (SC) re-emerged in 2024 due to the availability of low adsorption ultra-high pressure liquid chromatography (UHPLC) packed columns/instruments and large modalities being investigated in the context of cell and gene therapies. The physico-chemical principles of SC retention combined with hydrodynamic chromatography (HDC) exclusion have been recently reported. In SC, DNA macromolecules are retarded because: (1) they can be stretched to lengths comparable to the particle diameter, and (2) their elastic relaxation time is long enough to maintain them in non-equilibrium extended conformations under regular UHPLC shear flow conditions. Here, a quantitative HDC-SC retention model is consolidated. A general plate height model accounting for the band broadening of long DNA biopolymers along packed beds is also derived for supporting method development and predicting speed-resolution performance in SC.For illustration, the chromatographic speed-resolution properties in SC are predicted for the separation of specific critical pairs (4.0/4.5, 10/11, and 25/27 kbp) of linear dsDNA polymers. The calculations are performed for two available custom-made particle sizes, dp= 1.7 and 2.5μm, at a constant pressure of 10,000 psi. The predictions are directly validated from experimental data acquired using low adsorption MaxPeakTM 4.6 mm i.d. Columns packed with 1.7μm BEHTM 45 Å (15 cm long column) and 2.5μm BEH 125 Å (30 cm long column) Particles, and by injecting six linear dsDNAs (λ DNA-Hind III Digest). The LC system is very low dispersion ACQUITYTM UPLCTM I-class PLUS System, and the mobile phase is a 100 mM phosphate buffer at pH 8. Maximum resolution is always achieved when the average extended lengths of linear dsDNAs are equal to a critical length, which is proportional to the particle diameter and to the square root of the applied shear rate. Most advantageously, the experimental results reveal that the relaxation times of linear dsDNAs observed under shear flow conditions are two orders of magnitude shorter than those expected in the absence of flow: this enables the detection of the longest linear dsDNAs up to 25 kbp without irremediable loss in column performance. Finally, the retention-efficiency model elaborated in this work can be used to rapidly anticipate and develop methods (selection of particle size, column length, and operating pressure) for any targeted DNA and time-resolution constraints.

Enhanced Dissipation for Two-Dimensional Hamiltonian Flows

Let H∈C1∩W2,p\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H\\in C^1\\cap W^{2,p}$$\\end{document} be an autonomous, non-constant Hamiltonian on a compact 2-dimensional manifold, generating an incompressible velocity field b=∇⊥H\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$b=\ abla ^\\perp H$$\\end{document}. We give sharp upper bounds on the enhanced dissipation rate of b in terms of the properties of the period T(h) of the closed orbit {H=h}\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\{H=h\\}$$\\end{document}. Specifically, if 0<ν≪1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0<\ u \\ll 1$$\\end{document} is the diffusion coefficient, the enhanced dissipation rate can be at most O(ν1/3)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$O(\ u ^{1/3})$$\\end{document} in general, the bound improves when H has isolated, non-degenerate elliptic points. Our result provides the better bound O(ν1/2)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$O(\ u ^{1/2})$$\\end{document} for the standard cellular flow given by Hc(x)=sinx1sinx2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_{\ extsf{c}}(x)=\\sin x_1 \\sin x_2$$\\end{document}, for which we can also prove a new upper bound on its mixing rate and a lower bound on its enhanced dissipation rate. The proofs are based on the use of action-angle coordinates and on the existence of a good invariant domain for the regular Lagrangian flow generated by b.

Does rafting promote contemporary gene flow? Global and regional patterns of population genetic diversity and structure on the false limpet Siphonaria lateralis in the Southern Ocean

Rafting has been proposed as an effective mechanism for species without free-living pelagic larvae to achieve long-distance dispersal, theoretically preventing population differentiation over wide distributional ranges. Moreover, rafting has been advocated as a main dispersal mechanism for marine invertebrates with sub-Antarctic distributions, because of abundant buoyant kelps, driven by the Antarctic Circumpolar Current. Nonetheless, little attention has been given to the role of rafting to establish regular gene flow across the sub-Antarctic, and the geographic and temporal scales at which it occurs. Aiming to unravel these major questions about the extent of genetic connectivity across the Southern Ocean (SO), we studied the pulmonate limpet Siphonaria lateralis, a benthic species with encapsulated larvae, found on the rocky intertidal of sub-Antarctic islands and southern South America. Since S. lateralis is closely associated with D. antarctica, dispersal by rafting is plausible, as revealed by the absence of phylogeographic structure across the sub-Antarctic. We sampled 116 individuals from eight localities across the SO, and used 5,515 SNPs obtained through Genotyping-by-Sequencing, to determine contemporary genetic diversity, structure, and gene flow at two spatial scales; global, across the SO, and regional, within Kerguelen. Results identified substantial genetic structure, differentiating Patagonia, Falklands/Malvinas Islands, South Georgia and the Kerguelen archipelago, and low levels of contemporary gene flow. The most notable genetic differentiation was found between Patagonia/Falklands and South Georgia/Kerguelen. Structure was also significant between Patagonia and the Falkland/Malvinas Islands. Conversely, South Georgia and Kerguelen exhibited closer genetic affinity, and indications of recent but limited gene flow. Moreover, historical gene flow estimates between the four populations were low. At regional scale, noteworthy genetic structure persisted, and gene flow was insufficient to prevent genetic differentiation within Kerguelen. Consequently, rafting’s potential may be overestimated as a contemporary mechanism promoting gene flow across the SO, as these events may be sporadic, irregular, and unpredictable for marine invertebrates lacking a larval dispersal stage, since contemporary dispersal events don’t seem to facilitate high gene flow at both scales. Accordingly, other oceanographic factors or processes may hinder the establishment of species associated with macroalgae, and as consequence, contemporary genetic connectivity in the sub-Antarctic.

Price Dynamics and Integration of Onion Markets in India

The current study uses the Correlation matrix, Vector Auto Regressive model, Granger causality test and Instability index to investigate the level of market integration, price transmission and price instability in the key onion markets in India, namely, Azadpur, Bangalore, Belgaum, Hassan, Haveri, Hubli, Mysore, and Nashik. The findings provided substantial evidence for the co-integration and interdependence of these markets. Bangalore market has a positive relationship with the Nashik and Azadpur markets, with coefficients of 1.15 and 0.54, respectively. Bangalore and Belgaum displayed a solid, significant positive correlation with a coefficient of 0.770. Conversely, some markets show relatively weaker correlations, such as Azadpur and Hassan, with a coefficient of 0.389. Instability across major onion markets revealed that all the markets are volatile, as the instability index was more than 30 per cent. Since there is unidirectional causality from Hubli-Bangalore and Azadpur-Bangalore market pairs, it makes it necessary for future research to examine the influence of internal and external factors like market infrastructure, improving information technology to allow regular flow of market information to assist farmers in increasing their income. Keywords: Granger causality, instability, price transmission, price volatility. JEL Codes: B23, C01, C22, E31.

Common laryngopharyngeal reflux: A review

Abstract Clinically, gastroesophageal reflux disease (GERD) or gastroesophageal reflux disease (GORD) is a chronic upper gastrointestinal disease characterized by persistent and regular flow of stomach content up into the esophagus, resulting in symptoms and/or complications. Further, if acid reflux symptoms are more apparent in the larynx or pharynx, then the disorder may be called laryngopharyngeal reflux disorder (LPRD). The reflux of such acid to soft tissues beyond the esophagus will cause damage, which may turn into a relatively serious condition, especially for those with laryngeal reflux. Traditionally, obesity has been known as a primary risk factor for GERD or LPRD and related complications. Many studies have reported the association between obesity, hiatus hernia, and various motility dysfunctions of the upper gastrointestinal tract in patients with LPRD. Somehow obesity predisposes to these conditions, or whether they merely coexist with LPRD remains to be elucidated and dissents exist. Previous studies often recommend longer treatment and higher doses of proton pump inhibitors (PPI) for general gastroesophageal reflux because the presence of gastric acid in the pharynx and larynx can damage the vocal cords. Patients with laryngopharyngeal reflux can feel the symptoms while sitting at rest, and those with GERD feel the symptoms when lying down. The stomach contents, including pepsin and gastric acid, are the culprits that cause major damage to the tissues. Bile salts from the gallbladder further worsen the injury. A high-risk population includes people with obesity and/or obstructive sleep apnea.

Leakage monitoring of carbon dioxide injection well string using distributed optical fiber sensor

Whether the oil and gas fields in the Carbon Capture, Utilization, and Storage (CCUS) project use underground storage or energy supplementation to enhance oil recovery, they must be injected or monitored through the wellbore. Thus, the foundation and requirement for the safety of carbon dioxide (CO2) storage is the wellbore's integrity. When CO2 is dissolved in water, carbonic acid is created, and this acid strongly corrodes underground pipes. Therefore, the integrity issue with CO2 injection wells is more noticeable than with other wellbores. An annular pressure during gas injection is the primary symptom of gas injection string leakage in CO2 injection wells. This study aims to provide real-time pipe string monitoring using a distributed optical fiber temperature sensing system (DTS) and a distributed optical fiber acoustic sensing system (DAS). Variations in temperature and vibration are caused by annulus pressure relief or gas injection. Optical fiber logging, in contrast to traditional logging, has better performance indicators for optical fiber sensing apparatus. To adapt to complex wellbore conditions, it is necessary to enhance the temperature accuracy of DTS and the sensitivity and signal-to-noise ratio of DAS in CO2 drive injection wells based on the features of the gas injection string. To differentiate the leakage signal from the regular fluid flow signal, the energy calculation in the frequency band is done for DAS based on noise reduction, and the signal processing in the frequency band is done by the spectrum characteristics of the CO2 wellbore signal. The translation invariant wavelet algorithm is the primary denoising method for DTS, overcoming the shortcomings of traditional wavelet threshold algorithms such as excessive smoothing and the pseudo-Gibbs phenomenon. Furthermore, the depth correction during the optical cable lowering process is also examined in this paper. A CO2 gas injection well field experiment was conducted using this technology. A 1671m well was dug, and 1631m of optical cable were installed in the tubing. The tubing leakage position was successfully identified through gas injection, annulus pressure relief, and a comparison of DAS and DTS data. The field results demonstrate the accuracy with which the gas injection string integrity can be accurately monitored in real-time using distributed optical fiber sensing technology for CO2 injection wells.

Direct numerical simulation of open-channel flow over a heterogeneous particle bed at low relative submergence

This study investigates turbulent open-channel flows over beds of irregularly arranged particles, using direct numerical simulations at a friction Reynolds number of Reτ=300. Two distinct cases are examined: a polydisperse bed (P800) composed of multiple layers of randomly distributed spheres of varying sizes, and a monodisperse bed (M1015) formed by a random distribution of uniform sized spheres, with a bottommost single layer of varied-sized particles to introduce realistic randomness. Our investigation unveils a rich network of low- and high-speed streaks within the flow field, exhibiting distinctive behaviors in different bed configurations. The P800 case presents a poorly organized flow pattern induced by the varied particle sizes and arrangements, while the M1015 case shows a more regular flow pattern, marked by larger streaks. We also observe that total wall shear stress is substantially influenced by surface roughness-induced drag, extending beyond the effects documented in existing studies of open-channel flows. The present study reveals intricate secondary flow patterns over irregular particle beds. Large-scale circulations are discerned around particle crests in the P800 case and localized circulations with increased turbulence in the M1015 case. Furthermore, analysis of Reynolds stress tensor components indicates that roughness disrupts coherent turbulent eddies, consequently mitigating peak stress. We quantify correlations between drag force and local fluid velocity fluctuations. Notably, a larger deviation in drag is observed in the P800 case compared to M1015, accentuating the influence of particle size and distribution on fluid–particle interactions.

Mixing in two-dimensional shear flow with smooth fluctuations.

Chaotic variations in flow speed up mixing of scalar fields via intensified stirring. This paper addresses the statistical properties of a passive scalar field mixing in a regular shear flow with random fluctuations against its background. We consider two-dimensional flow with shear component dominating over smooth fluctuations. Such flow is supposed to model passive scalar mixing, e.g., inside a large-scale coherent vortex forming in two-dimensional turbulence or in elastic turbulence in a microchannel. We examine both the decaying case and the case of the continuous forcing of the scalar variances. In both cases dynamics possesses strong intermittency, which can be characterized via the single-point moments and correlation functions calculated in our work. We present general qualitative properties of pair correlation function as well as certain quantitative results obtained in the framework of the model with fluctuations that are short correlated in time.

Gastroesophageal reflux disease as a risk factor of dental hard tissues erosions

Gastroesophageal reflux disease (GERD) is a common chronic disease leading to a spontaneous and regular retrograde flow of gastric and/or duodenal contents into the esophagus. Reflux of the gastric contents into the oral cavity refers to the extraesophageal presentation of the disease, which, in the absence of timely treatment, can result in erosion of dental hard tissue (EDHT) through repeated exposure of the dental tissue to acidic contents. EDHT are non-carious lesions of the dental hard tissues (mainly enamel, and in some cases dentin), induced by a chemical reaction involving acids, which results in demineralization processes. The incidence rates of EDHT in adult patients with GERD are 32.5–51.5%. The EDHT in GERD develops in stages. Initially, the gradual degradation of tooth pelicula happens when it gradually becomes decayed by repeated acidic attacks. The loss of the pelicula results in direct contact of hydrochloric acid refluxate with the enamel surface and initiation of its demineralization at pH &lt; 5.5 with dissolution of hydroxyapatite crystals. Given the high prevalence of GERD in the population, it seems important to update an integrated approach to the treatment of such patients, which involves pharmacotherapy provided by the gastroenterologist, as well as prevention and minimally invasive treatment of presentations in the oral cavity by the dentist. Patients with EDHT due to GERD need to maintain individual oral hygiene (use mouth washes with a neutral pH level, avoid abrasive toothpastes), use remineralization therapy at home applying remogels (Tooth Mousse), and also be observed by a dentist as part of the follow-up care. Minimally invasive treatment by the dentist involves restorations using composite tooth filling materials and ceramic veneers. It is reasonable to empirically use proton pump inhibitors twice a day for 3 months for the direct treatment of GERD in patients with EDHT.

Growth of solitary slugs in long pipes

We show that a pipe transporting gas and liquid can be operated at conditions where both stratified flow and slug flow are stable. In this bi-stable flow regime, it is possible to observe stratified flow or regular hydrodynamic slug flow, depending on the inlet conditions. However, it is also possible to get one single slug at a time in the pipe. The distinctive characteristic of such “solitary” slugs is that they grow continuously as they travel along the pipe and therefore, in long pipelines, they can reach lengths up to thousands of pipe diameters and flood the downstream process installations. We first show how the length of solitary slugs can be predicted using slug tracking simulations. Based on those transient simulation results, we provide an explanation for the slug growth and we propose a simple quasi-steady-state model allowing us to predict the slug length in good agreement with the transient simulations. Finally, we explain how we can determine the boundaries of the bi-stable flow regime in which solitary slugs occur.

A SARS-CoV-2 outbreak in a public order and safety training facility in England, June 2021.

The public order and safety (POS) sector remains susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks, as workplace attendance is typically compulsory and close physical contact is often needed. Here, we report on a SARS-CoV-2 outbreak with an attack rate of 39% (9/23), which occurred between 19 and 29 June 2021 among a cohort of new POS recruits participating in a mandatory 18-week training programme in England. The COVID-OUT (COVID-19 Outbreak investigation to Understand Transmission) study team undertook a multidisciplinary outbreak investigation, including viral surface sampling, workplace environmental assessment, participant viral and antibody testing, and questionnaires, at the two associated training facilities between 5 July and 24 August 2021. Environmental factors, such as ventilation, were deemed inadequate in some areas of the workplace, with carbon dioxide (CO2) levels exceeding 1,500 ppm on multiple occasions within naturally ventilated classrooms. Activities during safety training required close contact, with some necessitating physical contact, physical exertion, and shouting. Furthermore, most participants reported having physical contact with colleagues (67%) and more than one close work contact daily (97%). Our investigation suggests that site- and activity-specific factors likely contributed to the transmission risks within the POS trainee cohort. Potential interventions for mitigating SARS-CoV-2 transmission in this POS training context could include implementing regular rapid lateral flow testing, optimizing natural ventilation, using portable air cleaning devices in classrooms, and expanding use of well-fitted FFP2/FFP3 respirators during activities where prolonged close physical contact is required.

A VERY COMPLEX CASE OF DORV TYPE FALLOT: A CASE REPORT

Abstract Double outlet right ventricle (DORV) is a rare CHD characterized by ventriculoarterial connection in which both great arteries arise entirely or predominantly from the right ventricle. Its prevalence is 0.9% of all CHDs. Several chromosomal abnormalities have been associated with DORV, including trisomy 13, trisomy 18, and chromosome 22q11 deletion. Hearts with DORV are an extremely heterogeneous group showing various morphological features, connections, and relationships at each level of the cardiac segments and intersegmental junctions. As a consequence, the clinical manifestations and required surgical procedures for patients with DORV are variable. The anatomical spectrum is higly variable: it can be associated with ventricular septal defect, transposition of the great arteries (TGA) and functional single ventricle. We report the case of an infant with prenatal diagnosis of CHD and finding partial duplication of the short arm of the X chromosome. Pregnant woman at 22 weeks comes to the outpatient clinic to perform follow–up ultrasound. At that site finding of CHD which was later confirmed at birth and therefore prostaglandin therapy was started. Echocardiogram showed a wide DIV from malalignment with antero–cephalic deviation of the conal septum with significant aortic destroposition configuring picture of double outlet right ventricle. It also presents a complex right efflux obstruction already at subvalvular pulmonary departure. The pulmonary valve presented dysplastic, with en dome motion, hypoplastic. Pulmonary perfusion appears to be provided predominantly by the Botallo‘s duct originating from the isthmic region of the aorta and leading with a long and tortuous course to the pulmonary confluence near the left pulmnary artery with high velocity flow. The remaining findings are normal. Therefore, in view of the clinical picture, he was subjected to palliative surgery of right systemic–pulmonary shunt between the brachiocephalic trunk and right pulmonary artery (modified Blalock–Taussing surgery) in 3.5mm PTFE and ligation of Botallo‘s duct. At subsequent follow–up, the systemic–pulmonary shunt appeared pervious with regular flow. Wide DIV from anterior malalignment with aorta cavalier to DIV. Severe stenosis at complex pulmonary outflow with max gradient up to 124mmHg with dynamic and valvular component. For the subsequent course of treatment, the patient will be discussed collegially.

Assessment of volume flow rate in arteriovenous fistulas with a novel ultrasound Doppler device (earlybird): Trend analysis, comparison of methods, and inter- and intra-rater reliability.

An accessible tool is required to analyze volume flow trends in arteriovenous fistulas for hemodialysis. Earlybird, an easy-to-place ultrasound Doppler device, has shown comparable accuracy to duplex ultrasound. In this study, we compared volume flow measurements obtained with duplex ultrasound and the dilution technique to an enhanced earlybird device, featuring a dual Doppler probe system, eliminating the requirement for a known insonation angle. Nine patients with a distal radiocephalic arteriovenous fistula were monitored for 12 months with regular volume flow measurements. Correlation and inter- and intra-class reliability analyses were conducted. An overall moderate correlation was observed between earlybird and duplex ultrasound or dilution technique (intraclass correlation coefficient = 0.606 (95% confidence interval 0.064, 0.721) and 0.581 (0.039, 0.739), respectively). Duplex ultrasound compared to dilution measurements, demonstrated an overall moderate correlation (0.725 (0.219, 0.843)). Correlation between earlybird and duplex ultrasound was stronger for the arteriovenous fistula (0.778 (0.016, 0.901)) than the brachial artery (0.381 (-0.062, 0.461)). For earlybird, inter-rater reliability was excellent for the arteriovenous fistula (0.907 (0.423, 0.930)) and poor for the brachial artery (0.430 (0.241, 0.716)). Duplex ultrasound showed a good inter-rater reliability (arteriovenous fistula: 0.843 (0.610, 0.871), brachial artery: 0.819 (0.477, 0.864)). The overall intra-rater reliability was good for duplex ultrasound (rater A: 0.893 (0.727, 0.911); rater B: 0.853 (0.710, 0.891)), while excellent for earlybird (rater A: 0.905 (0.819, 0.928); rater B: 0.921 (0.632, 0.969)). We observed a weaker correlation in the measurements of volume flow rates in arteriovenous fistulas when obtained using earlybird compared to dilution technique, unlike the comparison between duplex ultrasound and the dilution technique. However, inter-rater reliability for the arteriovenous fistula was excellent with earlybird and good with duplex ultrasound, indicating the potential of earlybird as a tool for frequent measurements, enabling trend surveillance and predicting adverse outcomes.

Controlling Couette flow by alternating axial mass flux

This paper presents numerical simulations of the Taylor vortex flow under the influence of an externally applied alternating axial mass flux (through-flow) in a Taylor–Couette system with axial periodic boundary conditions. Such an axially modulating flow can lead to a significant variation in the onset of primary instabilities. Depending on the system parameters, the effect can be both stabilizing and destabilizing, i.e., shifting the bifurcation threshold to larger or smaller control parameters, respectively. It is found that the system response around the primary instability is sensitive to and critically influenced by an alternating mass flux, particularly the modulation frequency. We show that such an alternating axial flow represents an easily and, more importantly, precisely controllable key parameter to change the nonlinear system response from subcritical to supercritical behavior and vice versa. Furthermore, we observe different parameter regimes with regular and irregular intermittent flow dynamics.

Numerical Hydrodynamic Modelling As A Tool For Research And Use Of Tidal Rivers

Tidal estuaries play a crucial role, serving as major hubs for economic activities while also contributing to the preservation of natural diversity and bioproductivity. In Russia, these estuaries are primarily located in remote regions of the European North and the Far East, making them vital for energy and transportation usage as they essentially form the ‘cores’ of territorial development along the Northern Sea Route. To facilitate the development of energy and navigation infrastructure in tidal estuaries, as well as to plan and implement environmental protection measures, it is essential to have a comprehensive understanding of their hydrological regime. Unlike regular river flow, tidal estuaries exhibit more complex hydrodynamics, influenced by both river and marine factors. Due to the considerable challenges of conducting field hydrological studies in remote areas, numerical hydrodynamic modelling has emerged as a valuable method for obtaining information on the flow and water level regime in tidal estuaries. This paper presents an application of one-dimensional HEC-RAS and two-dimensional STREAM_2D CUDA numerical models to investigate the parameters of reverse currents in the hypertidal Syomzha estuary flowing into the Mezen Bay of the White Sea. The limitations and accuracy of the models are discussed, along with the potential for their improvement considering recent advancements in understanding the hydraulics of reverse currents.

Quantitative assessment of the erosion and deposition effects of landslide-dam outburst flood, Eastern Himalaya

Both regular flow and infrequent outburst floods shape the mountain landscape, but their relative contributions have been widely debated, in part due to the paucity of quantitative data on historical outburst floods. In June 2000, an outburst flood was triggered by a landslide-dam failure in a rapidly exhumed region of the Eastern Himalaya. To investigate the role of this kind outburst flood on landscape evolution, we employ topographic differencing, satellite imagery, and 2D hydraulic simulations to quantify the equivalent erosion and deposition within ~ 80 km flood route downstream of the breach. The flood lasted for ~ 10 h, with a peak discharge of 105 m3/s, leading to average erosion of 10 m, and contributed ~ 1–2 × 103 times more sediment than over long-term mean fluvial processes. The flood produced extensive lateral erosion, which triggered a threefold widening of the valley floor and abundant subsequent landslides. The ubiquitous boulder bars deposited in the channel inhibited incision, and facilitated lateral erosion after the flood. The resulting channel configuration and extensive bank erosion continue to affect fluvial dynamics until the next catastrophic flood that remobilizes the boulders. Our quantitative findings highlight the profound importance of recurrent outburst floods for gorge development and landscape evolution in Eastern Himalaya.

2-D inverse synthetic aperture Ladar imaging and tracking of maneuvering extended Micro-Doppler UAVs in atmospheric turbulence with skewness

The inverse synthetic aperture Ladar (ISAL) is an important system for observation of space objects. Here, a 2-D ISAL imaging and tracking algorithm is proposed for low observable maneuvering extended objects tracking (M−EOT) such as small space UAVs. When imaging maneuvering objects with ISAL, dispersion and Doppler frequency time-variation exist in the range and cross-range echo signal, respectively. Additionally, the ISAL system can achieve high-resolution images for long-range moving objects, while its performance is affected by atmospheric turbulence. Atmospheric turbulence is a very complicated random state formed by the instability of regular laminar flow at a high maneuvering velocity, which is caused by the random motion of the atmosphere and lead to the random fluctuation of the atmospheric refractive index. Therefore, in real-time M−EOT scenario, the measurements distribution over the whole object is not symmetrical but distributed and skewed in some portions while a target maneuvers due to the unbalanced of reflection that caused by the atmospheric turbulence. In practice, the micro Doppler effect caused by micro moving components such as drone rotors will seriously affect the focused ISAL imaging of the M−EOT’s rigid body. To solve these problems in real-time low observable M−EOTs imaging and tracking from 2-D ISAL system, a novel robustness measurement model and recursion multi-Bernoulli track-before-detect filter based on a multiple model skewed non-symmetrically normal distribution is represented with more than one ellipse and lower complexity. In this paper, the Radon-Laplace method is presented to reduce this micro-Doppler effect in ISAL imaging. Additionally, we will eliminate the effect of atmospheric turbulence in ISAL Imaging by using the network-based variance–covariance estimation (NVCE) weighting method. In particular, we describe the M−EOT’s state through the random matrices model (RMM). In RMM, the extent is applied by one ellipse, which often lose information about size, heading, and shape, when the scatter centers are distributed symmetrically around the M−EOT’s centroid. In this paper, a new observation model used to modify a sub-RMM by considering the characteristics of 2-D ISAL data is proposed. Simulation results demonstrates the proposed robustness algorithm with the influence of the atmospheric turbulence and micro-Doppler.

DISTRIBUTION TRANSFORMER LIFE LOSS ANALYSIS ON JTM 20 KV DUE TO AMBIENT TEMPERATURE AND LOADING

A continuously operating transformer will inevitably undergo a temperature rise, with the iron core and copper coil as the primary sources of heat generation. The maximum temperature occurring in these components, also known as the hottest spot temperature, is the hottest point. It is essential to maintain a regular flow of temperature within safe limits to prevent any damage. The objective of this study is to estimate the remaining life of the distribution transformer at Tanjungpura University by analyzing its life shrinkage under JTM 20 kV's ambient temperature and loading conditions. To achieve this, transformer loading and top oil temperature were measured for one week. The Montsinger equation was utilized for calculating the transformer aging rate, while a service life of 20 years was assumed as per IEC 60354. Based on findings from research conducted at 4 locations, it was observed that the transformer experiences varying loads with temperature increases exclusively on weekdays from Monday to Friday. The age shrinkage values for each transformer were as follows: 0.0728 p.u, 0.0493 p.u, 0.0044 p.u, and 0.0043 p.u. Considering these research outcomes, the estimated remaining lifespan of the Tanjungpura University distribution transformer is long, and the transformer is in good condition.