Search results for "frequency"
showing 10 items of 2158 documents
Endovenous ablation of refluxing saphenous and perforating veins.
2017
Abstract. Since the end of the nineties endovenous thermal ablation and more recently non-thermal, non-tumescent techniques have been developed and improved. Until now, because of their favourable side effect profile in conjunction to sustained efficacy, in many countries they already replaced high ligation and stripping in the treatment of refluxing saphenous veins as well as for treatment of perforators and selected tributaries. Now, studies and comparative trials are available with long-term follow-ups for most of the techniques, providing valid data on occlusion and reflux rates, side effect profiles, and health related quality of life.
Optimal Damping Constant Investigation on a Quarter-Car
2013
This paper shows an investigation on optimal damping constant performed in the frequency domain. The optimal damping constant is meant as that value that minimizes the acceleration of all connected bodies characterizing a two degree of freedom system sketching a quarter car. The connected bodies are sprung and unsprung mass respectively for quarter of chassis and tire, this last keeps the contact with the ground and it is connected with the sprung mass through a shock absorber characterized by spring and fluid damper. Optimal damping constant was determined by imposing analytical conditions on the expression of acceleration of two masses. Afterwards, the variation of acceleration and positi…
Host-based divergence in populations of the pea aphid: insights from nuclear markers and the prevalence of facultative symbionts.
2003
In North America, the pea aphid Acyrthosiphon pisum encompasses ecologically and genetically distinct host races that offer an ideal biological system for studies on sympatric speciation. In addition to its obligate symbiont Buchnera, pea aphids harbour several facultative and phylogenetically distant symbionts. We explored the relationships between host races of A. pisum and their symbiotic microbiota to gain insights into the historical process of ecological specialization and symbiotic acquisition in this aphid. We used allozyme and microsatellite markers to analyse the extent of genetic differentiation between populations of A. pisum on pea, alfalfa and clover in France. In parallel, we…
Microscopic Insights into the Fluorite/Water Interfaces from Vibrational Sum Frequency Generation Spectroscopy
2016
Water/mineral interfaces are central to a wide range of environmental and technological processes. In this report we provide a quantitative, molecular-level understanding of the CaF2/water interface using Density Functional Theory-based molecular dynamics simulations. In particular through the comparison of calculated Vibrational Sum Frequency Generation spectra to the experimental ones, we give a structural characterisation of the interface at different pH. At low pH, the surface is positively charged, causing a substantial degree of water ordering. Our results suggest that the surface charge originates from the dissolution of fluoride ions of the topmost layer, rather than from proton ads…
Evolution of lactase persistence: an example of human niche construction
2011
Niche construction is the process by which organisms construct important components of their local environment in ways that introduce novel selection pressures. Lactase persistence is one of the clearest examples of niche construction in humans. Lactase is the enzyme responsible for the digestion of the milk sugar lactose and its production decreases after the weaning phase in most mammals, including most humans. Some humans, however, continue to produce lactase throughout adulthood, a trait known as lactase persistence. In European populations, a single mutation (−13910*T) explains the distribution of the phenotype, whereas several mutations are associated with it in Africa and the Middle …
Redox and autonomic responses to acute exercise-post recovery following Opuntia ficus-indica juice intake in physically active women
2021
Background: The aim of this study was to investigate if the supplementation with Opuntia ficus-indica (OFI) juice may affect plasma redox balance and heart rate variability (HRV) parameters following a maximal effort test, in young physically active women. Methods: A randomized, double blind, placebo controlled and crossover study comprising eight women (23.25 ± 2.95 years, 54.13 ± 9.05 kg, 157.75 ± 0.66 cm and BMI of 21.69 ± 0.66 kg/m2) was carried out. A juice containing OFI diluted in water and a Placebo solution were supplied (170 ml; OFI = 50 ml of OFI juice + 120 ml of water; Placebo = 170 ml beverage without Vitamin C and indicaxanthin). Participants consumed the OFI juice or Placebo…
TLR2 and age-related diseases: potential effects of Arg753Gln and Arg677Trp polymorphisms in acute myocardial infarction.
2008
ABSTRACT Inflammation is a key component of immune system. It is involved in both defense and pathophysiological events maintaining the dynamic homeostasis of host organism. Its function is controlled by innate immunity genes. Both their polymorphisms and environmental conditions give rise to different phenotypes in human population. Proinflammatory genotype may be beneficial in early life but not in old people. With advancing age, indeed, it increases the vulnerability and the intensity to inflammatory reactions responsible for the chronic inflammatory diseases, such as atherosclerosis and myocardial infarction (MI). Several studies have looked for detecting a genetic risk profile that mig…
SHIP2: A “NEW” Insulin Pathway Target for Aging Research
2014
Strong evidence suggests that systemic inflammation and central adiposity contribute to and perpetuate metabolic syndrome. All of these alterations predispose individuals to type 2 diabetes mellitus (T2DM), cardiovascular disease, as well as Alzheimer's disease (AD), all characterized by chronic inflammatory status. On the other hand, extensive abnormalities in insulin and insulin-like growth factor I (IGF-I) and IGF-II signaling mechanisms in brains with AD have been demonstrated, suggesting that AD could be a third form of diabetes. The Src homology domain-containing inositol 5-phosphatase 2 (SHIP2) has an important role in the insulin pathway because its over-expression causes impairment…
Mutational analysis of 105 mucopolysaccharidosis type VI patients
2007
Mucopolysaccharidosis type VI (MPS VI; Maroteaux-Lamy syndrome) is a lysosomal storage disorder caused by mutations in the N-acetylgalactosamine-4-sulfatase (arylsulfatase B, ARSB) gene. ARSB is a lysosomal enzyme involved in the degradation of the glycosaminoglycans (GAG) dermatan and chondroitin sulfate. ARSB mutations reduce enzyme function and GAG degradation, causing lysosomal storage and urinary excretion of these partially degraded substrates. Disease onset and rate of progression is variable, producing a spectrum of clinical presentation. In this study, 105 MPS VI patients—representing about 10% of the world MPS VI population—were studied for molecular genetic and biochemical parame…
Carotid intima-media thickness measurement through semi-automated detection software and analysis of vascular walls
2013
AIM: The aim of the present study was to compare the semi-automatic measurement of carotid intima thickness (RFQIMT - Esaote, Italy), with the conventional method. METHODS: We enrolle 81 patients, mean age 46 years ±15, with no history of cardio-cerebrovascular events and we assessed the traditional cardiovascular risk factors. We examined the IMT of the common carotid artery with manual and RFQIMT method (based on the "Radio Frequency" signal), according to the ASE protocol. RESULTS: Semi-automatic measurement was on average lower than manual measurement (617 μm ±191 vs. 676 μm ± 222) with a statistically significant difference (P<0.01). In agreement with manual measurements, the values of…