The onset of the Rayleigh-Benard convection (RBC) in a heated from above normal He-I layer in a cylindrical vessel in the temperature range T < T ≤ T (RBC in non-Oberbeck-Boussinesq approximation) is attended by the emergence of a number of vortices on the free liquid surface. Here, T = 2.1768 K is the temperature of the superfluid He-II-normal He-I phase transition, and the liquid density passes through a well-pronounced maximum at T ≈ T + 6 mK. The inner vessel diameter was D = 12.4 cm, and the helium layer thickness was ≈ 2.5 cm. The mutual interaction of the vortices between each other and their interaction with turbulent structures appeared in the layer volume during the RBC development gave rise to the formation of a vortex dipole (two large-scale vortices) on the surface. Characteristic sizes of the vortices were limited by the vessel diameter. The formation of large-scale vortices with characteristic sizes twice larger than the layer thickness can be attributed to the arising an inverse vortex cascade on the two-dimensional layer surface. Moreover, when the layer temperature exceeds T, convective flows in the volume decay. In the absence of the energy pumping from the bulk, the total energy of the vortex system on the surface decreases with time according to a power law.
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http://dx.doi.org/10.3390/ma14247514 | DOI Listing |
BMC Med Imaging
January 2025
Oxford Cardiovascular Clinical Research Facility, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, Level 1, Oxford Heart Centre, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK.
Background: Preterm birth (< 37 weeks' gestation) alters cerebrovascular development due to the premature transition from a foetal to postnatal circulatory system, with potential implications for future cerebrovascular health. This study aims to explore potential differences in the Circle of Willis (CoW), a key arterial ring that perfuses the brain, of healthy adults born preterm.
Methods: A total of 255 participants (108 preterm, 147 full-term) were included in the analysis.
Nefrologia (Engl Ed)
January 2025
Department of Ultrasound, The Second Hospital of Dalian Medical University, Dalian City, Liaoning Province, China. Electronic address:
Objective: As radiocephalic fistula is not necessarily appropriate for all patients with advanced kidney disease, our aim was to investigate the sensitive indicators that affect the functional primary patency of radiocephalic fistulas.
Methods: This prospective observational study included consecutive patients referred to the Second Hospital of Dalian Medical University for initial creation of radiocephalic fistula from July 2017 to December 2019. Preoperative ultrasound parameters, demographic characteristics, serum indicators and comorbidities were recorded.
J Vasc Surg
January 2025
Division of Vascular and Endovascular Surgery, Mayo Clinic, Rochester MN, USA. Electronic address:
Objectives: Celiac artery (CA) incorporation during FB-EVAR for complex abdominal aortic aneurysms (cAAA) is typically performed with fenestrations. Double-wide scallops (DWS) can be used when appropriate. We aimed to assess outcomes of patients treated with DWS for the CA during FB-EVAR for cAAA.
View Article and Find Full Text PDFJ Neurosci Methods
January 2025
IBME, Department of Engineering Science, University of Oxford, Oxford UK.
Background: Cerebrovascular reactivity (CVR) reflects the ability of cerebral blood vessels to adjust their diameter in response to vasoactive stimuli, which is crucial for maintaining brain health. Traditional CVR assessments commonly use a two-point measurement, assuming a linear relationship between cerebral blood flow (CBF) and arterial CO. However, this approach fails to capture non-linear characteristics, particularly the plateaus at extreme CO levels.
View Article and Find Full Text PDFMonaldi Arch Chest Dis
January 2025
Department of Cardiology, Izmir City Hospital, Izmir.
High blood levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) have been shown in various malignancies. In lung cancer, the importance of NT-proBNP is not clear. In this study, we aimed to investigate the significance of the correlation of NT-proBNP levels in lung cancer with tumor stage, tumor diameter, histopathology, and specific sites of mediastinal metastasis: lymphadenopathy; pericardial, cardiac, major vessel, other mediastinal organ or lymphatic involvement/invasion.
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