Search results for "Circulation"
showing 10 items of 1137 documents
The geochemistry of Tl and its isotopes during magmatic and hydrothermal processes: The peralkaline Ilimaussaq complex, southwest Greenland
2014
Abstract We use thallium (Tl) concentrations, K/Rb, K/Tl and Rb/Tl ratios and Tl isotopes in minerals from the alkaline to peralkaline Ilimaussaq complex (South Greenland) to trace magmatic differentiation, crustal assimilation, magmatic degassing, ore precipitation and hydrothermal metasomatism. Closed-system magmatic differentiation is marked by a coherent decrease of K/Tl- and K/Rb-ratios, whereas crustal assimilation results in a strong Tl-enrichment, causing low K/Tl-ratios compared to K/Rb-ratios. Thallium isotopes show only slight changes during orthomagmatic differentiation and the assimilation of crustal material cannot be traced, since the isotopic composition of the average crust…
Mutes gļotādas mikrocirkulācijas novērtējums izmantojot attēlvides fotopletizmogrāfiju
2019
Manipulācijas ar smaganām ir kļuvušas par standarta procedūrām zobārstniecībā rosinot nepieciešamību pēc smaganu funkcionālām izvērtēšanas metodēm. It īpaši tādēļ, ka smaganu klīniskā aina nevienmēr atspoguļo to funkcionālo stāvokli un morfoloģiskās īpatnības var nomaskēt funkcionālos traucējumus. Vietējā anestēzija ir neatņemama zobārstniecības procedūra, kas novērš pacienta diskomfortu manipulāciju laikā, taču dažreiz tā var radīt arī nevēlamās blakusparādības vai pat komplikācijas, kam ir vairāki iemesli (lielās devas, individuālā jutība uz kādu no anestēzijas komponentu, traucējumi pulpas un smaganu asins apgādē, vai pat neirotoksicitāte). Līdz ar to devas samazināšana ir ļoti svarīga, …
Remote photoplethysmography device with adaptive illumination for skin microcirculation assessment
2020
Measuring blood perfusion is important in medical care. However, currently available devices to measure blood perfusion are bulky, expensive and not easy-to-use. In this work a compact and portable low-cost prototype device for remote monitoring of palm skin microcirculation has been developed. Presented device consists of precisely controlled near-infrared illuminators (760nm peak wavelength) and video camera. The device with the custom designed software provides stable uniform illumination of curved skin surfaces, using feedback algorithm. Verification tests of this device showed improvements in the quality of skin blood perfusion maps in the case when the feedback system was used.
Photoplethysmography imaging algorithm for continuous monitoring of regional anesthesia
2016
An efficient photoplethy smography imaging system and advanced algorithm for continuous monitoring of skin microcirculation was developed. The system comprises compact device and computer with software for visualizing of skin blood volume changes. The software is able to process high-resolution microcirculation amplitude maps in real-time. It was tested in clinical environment during the regional anesthesia procedures. The Eulerian-based method showed improved sensitivity and higher resolution of microcirculation maps.
Ventilation/perfusion ratios measured by multiple inert gas elimination during experimental cardiopulmonary resuscitation
2014
Background During cardiopulmonary resuscitation (CPR) the ventilation/perfusion distribution (VA/Q) within the lung is difficult to assess. This experimental study examines the capability of multiple inert gas elimination (MIGET) to determine VA/Q under CPR conditions in a pig model. Methods Twenty-one anaesthetised pigs were randomised to three fractions of inspired oxygen (1.0, 0.7 or 0.21). VA/Q by micropore membrane inlet mass spectrometry-derived MIGET was determined at baseline and during CPR following induction of ventricular fibrillation. Haemodynamics, blood gases, ventilation distribution by electrical impedance tomography and return of spontaneous circulation were assessed. Inter…
Circulating Levels of Ferritin, RDW, PTLs as Predictive Biomarkers of Postoperative Atrial Fibrillation Risk after Cardiac Surgery in Extracorporeal …
2022
Postoperative atrial fibrillation (POAF) is the most common arrhythmia after cardiac surgery in conventional extracorporeal circulation (CECC), with an incidence of 15–50%. The POAF pathophysiology is not known, and no blood biomarkers exist. However, an association between increased ferritin levels and increased AF risk, has been demonstrated. Based on such evidence, here, we evaluated the effectiveness of ferritin and other haematological parameters as POAF risk biomarkers in patients subjected to cardiac surgery. We enrolled 105 patients (mean age = 70.1 ± 7.1 years; 70 men and 35 females) with diverse heart pathologies and who were subjected to cardiothoracic surgery. Their blood sample…
Heat in Normandy, types of atmospheric circulation and climate change (1970 - 2019)
2020
Heat in Normandy, synoptic circulation patterns and climate change (1970-2019). This article focuses on the role and the evolution of the different kinds of synoptic circulation patterns in the occurrence of hot days in Normandy. Heat is here, very dependent on the presence of action centres over central Europe as well as, air flow coming from NE and E. Contemporary climate change expresses itself by a rise in thermal efficiency of all synoptic circulation patterns (more heat for the same flow). Lastly, the north of Cotentin stands out by being a real “cool island” during summer because of its peninsula position which imposes on any air mass, regardless of its origin, a cooling from its bot…
Tropical Temperate Toughs over southern Africa: mechanisms and evolution in response to climate change
2015
In the Southern Hemisphere, Southern Africa and the south-west Indian Ocean are one of the three preferred regions where interactions between the tropics and midlatitudes develop. This is the South Indian Convergence Zone (SICZ), where northwest-southeast oriented cloud bands form at the synoptic scale (between 3 and 5 days). These bands are mainly found during the austral summer and are commonly referred to as tropical temperate troughs (TTTs). This research aims at improving our knowledge related to TTTs, with a study on the dynamics associated with these systems, and an analysis of their possible evolution during the 21st century.The first part of this thesis aims at identifying favorab…
Quantification of intracranial contribution to rheoencephalography by a numerical model of the head
2000
Abstract Objectives : Partial contributions of intracranial and extracranial circulation to rheoencephalography (REG) remain uncertain. The main goal of this work is to determine theoretically the capability of REG techniques to reflect intracranial blood flow. Methods : Head and current injection electrodes were computationally modeled to assess REG sensitivity to brain and scalp conductivity changes. Data obtained were related to tissue perfusions to calculate the partial contribution of cerebral blood perfusion to REG I, REG II and monopolar REG and to assess their amplitudes. Results : When REG I and monopolar REG were used, the theoretical maximum of intracranial contribution was reach…
Determination of volatile fatty acids in the hot springs of Vulcano, Aeolian Islands, Italy
1998
Abstract Samples of relatively acid hydrothermal fluids were collected in the spring of 1996 from seeps, springs, and wells on the Island of Vulcano in the southern Tyrrhenian Sea and analyzed for volatile fatty acids 1 using liquid chromatography. Concentrations of VFAs in the seeps were in the range 65–140 ppb formic, 133–184 ppb acetic, and