Search results for "CONSTANT"
showing 10 items of 1718 documents
Overexpression of the insulin-like growth factor I receptor in human pheochromocytomas.
2006
In order to determine the role of the IGF-I receptor (IGF-IR) in human pheochromocytomas we have compared the expression of the IGF-IR in normal tissues and in pheochromocytomas with regard to the IGF-IR mRNA levels and ligand binding. By semiquantitative reverse transcription polymerase chain reaction (RT-PCR), the mRNA of the IGF-IR could be detected in all samples of normal adrenomedullary cells (n=13) and pheochromocytomas (n=16). However, pheochromocytomas exhibited 2.8-fold higher mean IGF-IR mRNA levels than normal adrenomedullary cells (2.8±0.5×105 molecules/μg RNA vs 7.8±1.2×105 molecules/μg RNA; P < 0.001). This overexpression of the IGF-IR in pheochromocytomas could be confirm…
Testing utricular function by means of on-axis rotation
2005
Subjective visual vertical (SVV) estimation during on-axis rotation provides an efficient screening test of utricle function. The survey demonstrates that isolated disorders of peripheral utricular function can occur while SCC function appears normal.The present study aimed to investigate estimation of SVV during constant velocity yaw rotation (with the head held on-axis--to enhance any asymmetry between right and left utricular responses), as a useful screening test.In all, 230 patients were recruited from the dizziness clinic. For each patient, the SVV was estimated (a) while held stationary, and (b) during constant angular velocity (240 degrees/s), with the head centred on-axis. Bitherma…
Pharmacokinetics of atenolol in relation to renal function
1981
The plasma levels and urinary excretion of carteolol and its main metabolites 8-hydroxycarteolol and carteolol glucuronide were investigated in 6 healthy subjects and 9 patients with varying degrees of renal impairment following a single oral dose of 30 mg carteolol hydrochloride. In healthy subjects the half-life of carteolol was 7.1 h. 63% of the administered dose was recovered unchanged in urine, and in all 84% was excreted by the kidneys. The renal clearance of carteolol was 255 ml/min. In chronic renal failure (CRF) the terminal half-life was increased to a maximum of 41 h. Both the elimination rate constant and renal clearance were closely related to the creatinine clearance. In CRF t…
High Pressure Inside Nanometer-Sized Particles Influences the Rate and Products of Chemical Reactions
2021
International audience; The composition of organic aerosol has a pivotal influence on aerosol properties such as toxicity and cloud droplet formation capability, which could affect both climate and air quality. However, a comprehensive and fundamental understanding of the chemical and physical processes that occur in nanometer-sized atmospheric particles remains a challenge that severely limits the quantification and predictive capabilities of aerosol formation pathways. Here, we investigated the effects of a fundamental and hitherto unconsidered physical property of nanoparticles-the Laplace pressure. By studying the reaction of glyoxal with ammonium sulfate, both ubiquitous and important …
On reliability of systems with moving material subjected to fracture and instability
2015
Abstract The reliability of systems with moving cracked elastic and isotropic material is considered. The material is modeled as a moving plate which continually has a crack on the edge. The plate is subjected to homogeneous tension acting in the traveling direction and the tension varies temporally around a constant value, the set tension. The tension and the length of the crack are modeled by an Ornstein–Uhlenbeck process and an exponential Ornstein–Uhlenbeck process, respectively. Failure is regarded as the state at which the plate becomes unstable or fractures (or both) and a lower bound for the reliability of the system is derived. Considering reliability of the system leads to first p…
Thermodynamic Behavior of Non-Ionic Tri-block Copolymers in Water at Three Temperatures
2006
Apparent molar volumes (V Φ) of aqueous solutions of some copolymers, based on ethylene oxide (EO) and propylene oxide (PO) units, were determined as functions of concentration at three temperatures. Viscosity measurements were also carried out on some of these systems. The effects studied include how the molecular architecture and the molecular weight affect the aggregation of the copolymer, keeping constant the EO/PO ratio. Modeling of the volumetric data yielded the partial molar volume of the copolymer in the standard (V°) and the aggregated (V M) states, as well as the equilibrium constant for micellization and the aggregation number. Analysis of the viscosity data supported the insigh…
Thermodynamic properties of alcohols in a micellar phase. Binding constants and partial molar volumes of pentanol in sodium dodecylsulfate micelles a…
1984
Densities of the ternary system water-sodium dodecylsulfate (NaDS)-pentanol and of the binary systems butanol-octane and pentanol-octane were measured at 15, 25, and 35 °C. The apparent molar volume of pentanol in the ternary system was analyzed using a mass-action model for the alcohol distribution in micellar solutions. The partial molar volume of alcohol bound to the micelles and the ratio between the binding constant and the aggregation number of the surfactant are calculated. The partial molar volume binding constant, is discussed in terms of solubilization sites of the alcohol in the micelles whereas the binding constant is compared with that derived from the Nernstian partition const…
Influence of Duration of Experiment on Rate of Uptake of Radioactive Potassium in Smooth Muscle
1963
THE rates of uptake and loss of radioactive tracers by excitable tissues can often be described by a function involving one exponential term1–3, but over relatively long periods deviations have been observed from such a simple course4–7. The rates of exchange towards the end of such periods are commonly slower than would be predicted from the initial rates and two general causes for this behaviour have been suggested: either the rates are, in fact, diminishing during the course of an experiment or the tissue is not behaving uniformly. This latter possibility has been extensively investigated1,8–15, because biological material shows an obvious lack of uniformity, and because deviations from …
Bhabha Scattering and a special pencil of K3 surfaces
2018
We study a pencil of K3 surfaces that appeared in the $2$-loop diagrams in Bhabha scattering. By analysing in detail the Picard lattice of the general and special members of the pencil, we identify the pencil with the celebrated Ap\'ery--Fermi pencil, that was related to Ap\'ery's proof of the irrationality of $\zeta(3)$ through the work of F. Beukers, C. Peters and J. Stienstra. The same pencil appears miraculously in different and seemingly unrelated physical contexts.
Monolayers of asymmetrical diethylalkanoat disulfides on gold(111):.the influence of chain length difference on atomic force microscope images
1998
Several symmetrical and asymmetrical long-chain diethylalkanoat disulfides were synthesized and character- ized. The differences in the chain lengths of the disul- fides ranged between zero and five methylene units. Self- assembled monolayers of these disulfides formed on Au(111) surfaces were studied by atomic force microscopy (AFM) in order to obtain information about the origin of the image contrast. Domains with hexagonal lattices (lattice constants 5:2- 5:3 A) were detected for all derivatives, independent of the chain length differences. This indicates that the contrast arises roughly at a depth of 4- 8 A in the monolayers at imag- ing forces between 0: 2a nd 3n N. For SAMs of diethyl…