Search results for " Pressure"
showing 10 items of 3868 documents
Why People Don’t Use Facebook Anymore? An Investigation Into the Relationship Between the Big Five Personality Traits and the Motivation to Leave Fac…
2020
This study linked the big five personality traits with motivational factors to leave Facebook based on a survey of 218 former Facebook users. The big five were related with eight main factors retrieved from existing literature. Results showed that neuroticism was positively related to addiction, banality, peer pressure, and privacy while conscientiousness was negatively related to peer pressure, addiction, annoyance, and emergence of new platforms. Openness was positively related with banality but negatively with addiction and peer pressure. Theoretical and practical interpretations are also discussed.
Data from: How do cuticular hydrocarbons evolve? Physiological constraints and climatic and biotic selection pressures act on a complex functional tr…
2016
Cuticular hydrocarbons (CHCs) cover the cuticles of virtually all insects, serving as a waterproofing agent and as a communication signal. The causes for the high CHC variation between species, and the factors influencing CHC profiles, are scarcely understood. Here, we compare CHC profiles of ant species from seven biogeographic regions, searching for physiological constraints and for climatic and biotic selection pressures. Molecule length constrained CHC composition: long-chain profiles contained fewer linear alkanes, but more hydrocarbons with disruptive features in the molecule. This is probably owing to selection on the physiology to build a semi-fluid cuticular layer, which is necessa…
Data from: Propagule pressure increase and phylogenetic diversity decrease community’s susceptibility to invasion
2017
Invasions pose a large threat to native species, but the question of why some species are more invasive, and some communities more prone to invasions than others, is far from solved. Using ten different three-species bacterial communities, we tested experimentally if the phylogenetic relationships between an invader and a resident community and propagule pressure affect invasion probability. We found that greater diversity in phylogenetic distances between the resident community members and the invader lowered invasion success, and higher propagule pressure increased invasion success whereas phylogenetic distance had no clear effect. In the later stages of invasion phylogenetic diversity ha…
Data from: Noninvasive assessment of respiratory muscle strength and activity in Myotonic dystrophy
2018
Objective To evaluate sensitivity/specificity of the maximum relaxation rate (MRR) of inspiratory muscles, amplitude of electromyographic activity of the sternocleidomastoid (SCM), scalene (SCA), parasternal (2ndIS) and rectus abdominis (RA) muscles; lung function and respiratory muscle strength in subjects with Myotonic dystrophy type 1 (DM1) compared with healthy subjects. Design and methods Quasi-experimental observational study with control group. MRR of inspiratory muscles, lung function and amplitude of the electromyographic activity of SCM, SCA, 2ndIS and RA muscles during maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax) and sniff nasal inspiratory pressure (…
Data from: An aposematic colour-polymorphic moth seen through the eyes of conspecifics and predators - sensitivity and colour discrimination in a tig…
2019
1. Although predation is commonly thought to exert the strongest selective pressure on colouration in aposematic species, sexual selection may also influence colouration. Specifically, polymorphism in aposematic species cannot be explained by natural selection alone. 2. Males of the aposematic wood tiger moth (Arctia plantaginis) are polymorphic for hindwing colouration throughout most of their range. In Scandinavia, they display either white or yellow hindwings. Female hindwing colouration varies continuously from bright orange to red. Redder females and yellow males suffer least from bird predation. 3. White males often have higher mating success than yellow males. Therefore, we ask wheth…
Mechanisms of Cell-Volume Regulation in the Central Nervous System
2017
Function and viability of every cell is dependent on the proper control of its shape and volume. In the brain, which is protected by a rigid outer shell, cell-volume regulation is of particular importance, since large volume changes affect cerebral perfusion and, hence, function. Neuronal activation leads to constant changes of the ionic and metabolic composition of the brain’s extracellular space. These changes are buffered by astrocytes on the expense of constant changes in cell volume. Under pathological conditions, the ability of astrocytes to maintain the homeostasis of the brain is overwhelmed and permanent cell swelling, cytotoxic edema, occurs. The current chapter describes the prin…
Functional Morphology of Human Arteries During Fetal and Postnatal Development
1980
The equilibrium between the distending force of the blood pressure and the arterial wall is determined essentially by a simple law of mechanics, the law of Laplace. According to this law, the total force or tension (T) in the vessel’s wall represents the product of the radius of the vessel (r) and the blood pressure (p), T = r.p. The law of Laplace may be used to estimate and compare the tension produced by blood pressure in vessels of different size and thereby determine the increase in functional load on arteries. Since tension increases not only with blood pressure but also with the radius of the vessel, the highest tension is presumably produced in the wall of the ascending aorta where …
Determination of the Optimal Saddle Height for Leisure Cycling (P188)
2008
Several studies have been done on road racing cycling and triathlon to determine the optimal saddle height (LINF) in terms of efficiency. However, cycling is becoming nowadays not only a popular sport but also a mass mean of transport were comfort takes priority over efficiency. The aim of this study is to determine an optimal saddle height (LINF) to improve comfort in leisure cycling. Five male subjects (height mean=172.2 cm, std=1.34 cm; crotch height mean=81.25cm, std=0.88cm) tested 9 prototypes of the company ORBEA with 3 levels of LINF. The test consisted in one hour cycling in lab conditions and four different techniques were used to evaluate the LINF: 3-D movement analysis was used t…
19F-MRI of perflubron for measurement of oxygen partial pressure in porcine lungs during partial liquid ventilation
2001
A method for in vivo measurement of oxygen partial pressure (pO2) in porcine lungs during partial liquid ventilation (PLV) with perflubron (PFOB) was developed. A pulse sequence for high-resolution MRI of the distribution of PFOB in the lung after intratracheal administration was developed as well. Moreover, quantitative measurements of longitudinal relaxation time T(1) of (19)F resonances for assessment of regional pO2 are described. Due to the need to acquire data during a single expiratory breathhold, only low SNRs were achieved in vivo. Therefore, simulations were performed to investigate the influence of background noise on T(1) values calculated from data with low SNR. Based on these …
Changes of plasma endothelin and growth factor levels, and of left ventricular mass, after chronic AT1-receptor blockade in human hypertension.
1998
The stimulation of autocrine and paracrine factors such as basic fibroblast- (bFGF) and platelet-derived (PDGF) growth factors mediates many of the growth-promoting actions of angiotensin II. The aim of this study was to evaluate the effect of chronic AT1-receptor blockade on plasma endothelin-1 (ET-1) and growth factors levels, and on left ventricular mass, in essential hypertension (EH). The study population consisted of 16 patients with mild-moderate EH, and 25 normotensive controls. In the EH patients under basal conditions, and after 3 and 6 months of chronic therapy with Losartan 50 mg/day, we measured serum levels of ET-1, bFGF and PDGF, and tumor necrosis factor (TNF). At the same t…