Search results for "valve"
showing 10 items of 576 documents
Deguna vārsta kustīguma kvantitatīvs novērtējums
2018
Pamatojums: Deguna vārsts ir visšaurākais reģions visos augšējos elpceļos. Tā ir kustīgā deguna daļa, kas tiek uzskatīta par STARLING-rezistoru. Lai paplašinātu vai stabilizētu deguna vārstu, ir publicētas dažādas palīgierīces un metodes, taču indikācijas to izmantošanai ir balstītas vien uz ķirurgu personīgo pieredzi. Mērķis: Veikt objektīvu deguna vārsta lomas novērtējumu. Materiāli un metodes: Pētījumā tika iekļauti 30 brīvprātīgie, kuriem ar elastīgu tērauda elementu, fiksētu pie galvas lentes un aprīkotu ar deformācijas sensoru (strain gauge), tika precīzi izmērīta deguna laterālās sienas novirze tās dziļākajā punktā elpošanas laikā. Novirzes kalibrācija tika veikta ar speciālām kalibr…
Climate signatures on decadal to interdecadal time scales as obtained from mollusk shells (Arctica islandica) from Iceland
2013
Abstract Pronounced decadal climate oscillations are detected in a multi-centennial record based on shell growth rates of the marine bivalve mollusk, Arctica islandica, from Iceland. The corresponding analysis of patterns in sea level pressure and temperature exhibit large-scale teleconnections with North Atlantic climate quantities. We find that the record projects onto blocking situations in the northern North Atlantic. The associated circulation shows a low-pressure signature over Greenland and the Labrador Sea and a high-pressure system over Western Europe associated with northeasterly flow towards Iceland and weakening in the westerly zonal flow over Europe. It can be speculated that s…
The shell matrix of the freshwater mussel Unio pictorum (Paleoheterodonta, Unionoida). Involvement of acidic polysaccharides from glycoproteins in na…
2007
13 pages; International audience; Among molluscs, the shell biomineralization process is controlled by a set of extracellular macromolecular components secreted by the calcifying mantle. In spite of several studies, these components are mainly known in bivalves from only few members of pteriomorph groups. In the present case, we investigated the biochemical properties of the aragonitic shell of the freshwater bivalve Unio pictorum (Paleoheterodonta, Unionoida). Analysis of the amino acid composition reveals a high amount of glycine, aspartate and alanine in the acid-soluble extract, whereas the acid-insoluble one is rich in alanine and glycine. Monosaccharidic analysis indicates that the in…
Variation of environmental condition and diet act on immune parameters of Mytilus galloprovinciali
2015
Variation of environmental condition and diet act on immune parameters of Mytilus galloprovincialis The knowledge of the immunity mechanisms as environmental indicators and their alterations in the case of physical stress can be of fundamental importance in the environmental management programs. Recently has been shown that environmental factors affect immune responses in some species of bivalves. In this study we assessed different enzymatic activities from digestive gland of M. galloprovincialis such esterase, phosphatase and phenoloxidase (PO), involved in digestive inflammatory, detoxification and melanization processes. Particularly, esterases catalyze the hydrolysis reaction of the es…
On the Modeling of Transcatheter Therapies for the Aortic and Mitral Valves: A Review
2022
Transcatheter aortic valve replacement (TAVR) has become a milestone for the management of aortic stenosis in a growing number of patients who are unfavorable candidates for surgery. With the new generation of transcatheter heart valves (THV), the feasibility of transcatheter mitral valve replacement (TMVR) for degenerated mitral bioprostheses and failed annuloplasty rings has been demonstrated. In this setting, computational simulations are modernizing the preoperative planning of transcatheter heart valve interventions by predicting the outcome of the bioprosthesis interaction with the human host in a patient-specific fashion. However, computational modeling needs to carry out increasingl…
Review of immediate cardiac response in intertidal gastropods limpets at varying temperature, salinity and air exposure
2009
In 1990 Depledge and Andresen developed a #eld/laboratory, non-invasive technique to monitor the immediate response of cardiac activity in bivalves. Since then, several researchers have experienced and tested the variability of heart beat rate (HBR)and of associated metabolic rates under di$erent conditions in intertidal molluscs. Review of HBR immediate response in acute exposure and acclimation to changes of salinity, thermal stressors and air exposure were examined to test di$erent hypothesis. In intertidal Mediterranean and tropical limpets, the decrease in metabolic rate with a decrease in salinity was di$erent in animals experiencing di$erent degrees of salinity !uctuation in their re…
Local food availability affects invasion ability of alien bivalves: an experimental and simulation integrated approach
2009
The Lessepsian bivalve Brachidontes pharaonis is considered as one of 100 worst invasive species in the Mediterranean rapidly colonizing the most part of the Basin. Its current distribution seems primarily due to ship transport of carrying larvae by ballast waters and/or in the fouling attached beneath the ship-keels. Although humanmediated transport seems to potentially in!uence dispersal of invasive species, habitat suitability, temperature, salinity and food availability (i.e. in terms of quality and quantity of organic matter) seem to represent decisive factors in determining survivorship and distribution of this species. Physiological tolerance of B. pharaonis to temperature and salini…
Heart beat rate: a physiological response to thermal stress in blue mussels species.
2009
Non-native species often have ecological impacts on invaded communities. The quanti#cation of features of invaders and recipient ecosystems facilitating and/or interfering with successful invasion remains a challenge because of several factors may in!uence the success of invasions. Among them, life history strategies (e.g., reproductive potential, body size), ability to avoid predators, disease resistance and physiological compensatory mechanisms to adapt to changing habitats are among the most important factors. The latter has been often invoked as the key to success for many intertidal invasive invertebrates and have been suggested as key indicators of invasibility rate and the ultimate d…
Scope for Growth of the intertidal Lessepsian bivalve Brachidontes pharaonis (Fischer 1870) at varying environmental variables
2009
The concept of energy available to organismal growth (i.e. scope for growth; SFG) assumes a central role in studying the behaviour of successful invaders in aquatic habitats: the higher the energy allocated to growth and reproduction, the greater the likelihood of stability/persistence in space over time of aquatic populations. When successful invaders find useful life conditions (i.e., allowing to reach maximum SFG), they compete for space and resources with indigenous species, altering the functioning of entire ecosystems. The Indo-Pacific bivalve Brachidontes pharaonis offers an excellent model for the study of “Lessepsian migration” and the successive colonization at new Mediterranean l…
Interaction between the endangered freshwater pearl mussel Margaritifera margaritifera, the duck mussel Anodonta anatina and the fish host (Salmo) : …
2018
The common duck mussel Anodonta anatina can live in sympatry with—and use the same host, brown trout (Salmo trutta)—as the endangered freshwater pearl mussel Margaritifera margaritifera. Since the glochidia release of A. anatina takes place seasonally earlier than that of M. margaritifera, brown trout can be sequentially exposed first to A. anatina and then to M. margaritifera. Cross-immunity, an immune reaction induced in fish host against glochidia after the infection with glochidia of another mussel species, is possible. Thus, it was studied experimentally if brown trout can be cross immunized against M. margaritifera by earlier infection with A. anatina. In addition, the hypothesis that…