Search results for "RESISTANCE"
showing 10 items of 3641 documents
Introduction to Spintronics
2015
Spintronics was born in 1988 with the discovery of GMR provided simultaneously by A. Fert and P. Grunberg and rewarded in 2007 with the Nobel Prize in Physics. This field has since been largely exploited on the market, for example it has been at the base of every hard disk read head. Spintronics field is extremely active and interesting from both a fundamental point of view and for technological applications. Currently, with the aim at new functionalities, there is an increased activity from materials research perspective to understand and develop spintronics devices using materials with new properties like carbon nanotubes, graphene, topological insulators and molecules. This chapter will …
Vibration Detector based on GMR Sensors
2007
Up to now, vibrations have been mostly sensed by measuring displacement, velocity and acceleration. The most common types of vibration sensors are piezoelectric, capacitive, null-balance, strain gage, optoelectronic, resonance beam or piezoresistive. We present a low cost and low power vibration detector based on the measurement of magnetic field variations induced in a recent SS501 GMR magnetic sensor, which has never been applied for that. Vibrations on small ferromagnetic pieces disturb the Earth's magnetic field. These weak perturbations can be detected and measured over the assumed constant Earth's magnetic field, which is uniform over a wide area. A novel array configuration of 3 half…
Vibration Detector Based on GMR Sensors
2009
Up to now, vibrations have mostly been sensed by measuring displacement, velocity, and acceleration. The most common types of vibration sensors are piezoelectric, capacitive, null-balance, strain gage, optoelectronic, resonance beam, and piezoresistive. We present a low-cost and low-power vibration detector based on the measurement of magnetic field variations induced in a recent SS501 giant magnetoresistance (GMR) magnetic sensor, for which has never been applied. Vibrations on small ferromagnetic pieces disturb the Earth's magnetic field. These weak perturbations can be detected and measured over the assumed constant Earth's magnetic field, which is uniform over a wide area. A novel array…
Dynamic $\mathrm{R}_{\mathrm{ON}}$ evaluation of commercial GaN HEMT under different switching and radiation conditions
2019
This paper focus on the study of dynamic resistance $(\mathrm{R}_{\mathrm{dyn}})$ over commercial Gallium Nitride High Electromobility Transistors (GaN HEMTs) devices. The first part shows a study of the main mechanism causing $\mathrm{R}_{\mathrm{dyn}}$ , showing that depending on the structure, stress time, voltage applied and switching conditions, the $\mathrm{R}_{\mathrm{dyn}}$ can suffer a relevant increase. Also, it is demonstrated how the use of soft-switching conditions can alleviate trapping effects. Finally, due to the interest over these devices for future space applications, the effects of gamma radiation over the $\mathrm{R}_{\mathrm{dyn}}$ has been studied.
The Influence of a Magnetized Plasma Column on the Radiation Characteristics of a Strip Loop Antenna
2014
The radiation characteristics of a circular loop antenna located on the surface of an open waveguide in the form of an axially magnetized plasma column are studied using the rigorously obtained current distribution of such an antenna. The radiation resistance of the antenna excited by a time-harmonic external voltage is obtained for the case where the plasma inside the column is resonant. The distribution of the radiated power over the spatial spectrum of the excited waves is found and discussed.
Entropic approach to estimate the mean flow velocity: experimental investigation in laboratory flumes
2015
The paper deals with the linear entropic relationship between the maximum velocity, u max , and the mean flow velocity, u m , through a dimensionless parameter Φ(M), in open-channel flow. The analysis is conducted with the aid of experimental data collected in straight laboratory flumes under different bed and side-walls roughness conditions. In particular, rough/vegetated beds and smooth/rough side-walls conditions have been investigated. The results show that, in the investigated conditions (with exception of low-submergence vegetated bed—h/k v < 2), Φ(M) can be assumed equal to a value that is very close to that found in natural channels. This demonstrates that Φ(M) is able to implicitl…
Effects of carboxyamidotriazole on in vitro models of imatinib-resistant chronic myeloid leukemia.
2008
Although imatinib mesylate (IM) has revolutionized the treatment of chronic myeloid leukemia (CML), some patients develop resistance with progression of leukemia. Alternative or additional targeting of signaling pathways deregulated in bcr-abl-driven CML cells may provide a feasible option for improving clinical response and overcoming resistance. In this study, we show that carboxyamidotriazole (CAI), an orally bioavailable calcium influx and signal transduction inhibitor, is equally effective in inhibiting the proliferation and bcr-abl dependent- and independent-signaling pathways in imatinib-resistant CML cells. CAI inhibits phosphorylation of cellular proteins including STAT5 and CrkL a…
Hemodilution in isolated tumor perfusion.
1984
Experiments are performed to study the influence of local hemodilution on tumor blood flow, oxygen availability in tumor tissue and O2 consumption of cancer cells. The results obtained clearly show that hemodilution in isolated tumor perfusion can distinctly improve nutritive blood flow through solid tumors. This can be utilized to enhance pharmacokinetics of antitumor drugs. Due to the improved metabolic status, the pharmacodynamics of some antitumor drugs should also be enhanced. To achieve a maximum improvement of the O2 supply to the tumor, hematocrit values should not be decreased below 0.20.
Defense Responses of Fusarium oxysporum to 2,4-Diacetylphloroglucinol, a Broad-Spectrum Antibiotic Produced by Pseudomonas fluorescens
2004
A collection of 76 plant-pathogenic and 41 saprophytic Fusarium oxysporum strains was screened for sensitivity to 2,4-diacetylphloroglucinol (2,4-DAPG), a broad-spectrum antibiotic produced by multiple strains of antagonistic Pseudomonas fluorescens. Approximately 17% of the F. oxysporum strains were relatively tolerant to high 2,4-DAPG concentrations. Tolerance to 2,4-DAPG did not correlate with the geographic origin of the strains, formae speciales, intergenic spacer (IGS) group, or fusaric acid production levels. Biochemical analysis showed that 18 of 20 tolerant F. oxysporum strains were capable of metabolizing 2,4-DAPG. For two tolerant strains, analysis by mass spectrometry indicated…
Three-dimensional cell cultures: from molecular mechanisms to clinical applications.
1997
This article reviews actual advances in the development and application of three-dimensional (3-D) cell culture systems. Recent therapeutically oriented studies include characterization of multicellular-mediated drug resistance, novel ways of quantifying hypoxia, and new approaches to more efficient immunotherapy. Recent progress toward understanding the development of necrosis in tumor spheroids has been made using novel spheroid models. 3-D cultures have been used for studies on molecular mechanisms involved in invasion and metastasis, with a major focus on the role of E-cadherin. Similarly, tumor angiogenesis and the significance of vascular endothelial growth factor have been investigat…