Search results for " density"

Optical addressing at the subwavelength scale

2000

The Green dyadic formalism is applied to the study of the optical properties of dielectric subwavelength structures integrated in coplanar geometry. We first consider homogeneous wires with high refractive index featuring subwavelength cross sections. We show that such wires may have guiding properties and that they may be coupled with a local illumination produced by a focused Gaussian beam totally reflected at the substrate interface. When excited by the focused beam, these subwavelength optical waveguides (SOW's) provide a confined source of light that could be used to excite a single nanoscopic object. Well designed heteregeneous wires resulting from the alignment of dielectric particle…

Centrifugation does not alter spatial distribution of `BEP4' mRNA in paracentrotus lividus EGG

1997

AbstractParacentrotus lividus unfertilized eggs were centrifuged in a sucrose gradient, so to split each into two parts: a nucleated light fragment and an anucleated heavy fragment. Northern blot analyses utilizing a bep4 probe as animal marker and H2A histone gene and 12S-mit RNA as controls indicate that the eggs are elongated along the animal-vegetal axis during centrifugation and thereafter split into an animal and a vegetal half. Treatment of the eggs with colchicine before centrifugation abolishes the animal localization of bep4 mRNA.

Quantitative analysis of crystal/grain sizes and their distributions in 2D and 3D

2011

Abstract We review methods to estimate the average crystal (grain) size and the crystal (grain) size distribution in solid rocks. Average grain sizes often provide the base for stress estimates or rheological calculations requiring the quantification of grain sizes in a rock’s microstructure. The primary data for grain size data are either 1D (i.e. line intercept methods), 2D (area analysis) or 3D (e.g., computed tomography, serial sectioning). These data have been used for different data treatments over the years, whereas several studies assume a certain probability function (e.g., logarithm, square root) to calculate statistical parameters as the mean, median, mode or the skewness of a cr…

Long lasting high fat feeding increases the capillary density in the skeletal muscle of mice

2010

O2Transport in Skeletal Muscle: Development of Concepts and Current State

1994

When comparing oxygen consumption rates(V O2) of various organs — as shown in Fig. 1 —skeletal muscle is exceptional in two respects: Its consumption rate attains the second largest absolute value of all organs and may vary between rest (0.2 mlO 2.100g-1’• min -1 ) and maximum performance (16 m1O 2.100g-1 • min -1 for electrical stimulation) by a factor of 80, thus covering a range that is by far larger than in any other tissue. In order to understand muscle O 2 transport one has to identify transport mechanisms and evaluate their importance towards bringing about the observed high O 2 fluxes and allowing for their enormous variability.

Minkowski-Lorentz Spaces Applications: Resolution of Apollonius and Dupin Problems

2019

International audience

The antioxidant effect in controlling thermal degradation of a LDPE blow film

2004

It is well known that antioxidants are widely used to prevent thermal degradation of high density and linear low density polyethylene. Antioxidants are not always present in low density polyethylene and only small amounts are usually added to these resins. In this work the effect of an antioxidant system on a low density resin having MFI (190 °C/2.16 kg)=2 g/10′ and density 0.9230 g/cm3 has been studied. Its effect on melt viscosity has been studied by means of a batch mixer and the torque vs time behaviour has been analysed. The results show that a maximum in the torque vs time curve can be seen for the material containing antioxidant. In contrast, the material without antioxidant does not…

Imaging of metabolic bone disease

2018

Osteoporosis is the most important metabolic bone disease, with a wide distribution among the elderly. It is characterized by low bone mass and micro architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk. Identify bone weakening with an appropriate and accurate use of diagnostic imaging is of critical importance in the diagnosis and follow-up of osteoporotic patients. The aim of this review is to evaluate the detection rates of the different imaging modalities in the evaluation of bone strength, in the assessment of fracture risk and in the management of fragility fractures. (www.actabiomedica.it)

Functional MRI of the lung using hyperpolarized 3-helium gas

2004

Lung imaging has traditionally relied on x-ray methods, since proton MRI is limited to some extent by low proton density in the lung parenchyma and static field inhomogeneities in the chest. The relatively recent introduction of MRI of hyperpolarized noble gases has led to a rapidly evolving field of pulmonary MRI, revealing functional information of the lungs, which were hitherto unattainable. This review article briefly describes the physical background of the technology, and subsequently focuses on its clinical applications. Four different techniques that have been used in various human investigations are discussed: ventilation distribution, ventilation dynamics, and small airway evaluat…

Quantitative Lung Ultrasound: Technical Aspects and Clinical Applications.

2021

Lung ultrasound is increasingly used in emergency departments, medical wards, and critical care units—adult, pediatric, and neonatal. In vitro and in vivo studies show that the number and type of artifacts visualized change with lung density. This has led to the idea of a quantitative lung ultrasound approach, opening up new prospects for use not only as a diagnostic but also as a monitoring tool. Consequently, the multiple scoring systems proposed in the last few years have different technical approaches and specific clinical indications, adaptable for more or less time-dependent patients. However, multiple scoring systems may generate confusion among physicians aiming at introducing lung …