1,053 research outputs found
On Lie Algebroids and Poisson Algebras
We introduce and study a class of Lie algebroids associated to faithful
modules which is motivated by the notion of cotangent Lie algebroids of Poisson
manifolds. We also give a classification of transitive Lie algebroids and
describe Poisson algebras by using the notions of algebroid and Lie
connections
Laterally pumped GaAs/AlGaAs quantum wells as sources of broadband terahertz radiation
In this work we consider lateral current pumped GaAs/AlGaAs quantum wells as sources of incoherent terahertz radiation. The lateral field heats the electrons in a two-dimensional quantum layer and increases the population of higher subbands, hence also increasing the radiation power generated in spontaneous intersubband emission processes. Digitally graded quasi-parabolic and simple square quantum wells are considered, and the advantages of both types are discussed. Calculations at lattice temperatures of 77 K and 300 K, for electric fields up to 10 kV/cm, show that the optical output power of ~100−200 W/m2 may be achieved for the 7 THz source. The main peak of the spectrum, at 7 THz, of the quasi-parabolic quantum well exceeds the black body radiation at 300 K by approximately a factor of two and by two orders of magnitude at 77 K
Diazepam inhibits cell respiration and induces fragmentation of mitochondrial reticulum
AbstractDiazepam (70–150 μg/ml) significantly inhibits oxygen consumption by pig kidney embryo cells and causes the cellular ATP level to fall. The maximum inhibitory effect develops after 1.5–2.5 h of diazepam treatment. In isolated mitochondria diazepam inhibits respiration in state 2 and 3u with glutamate and in state 3u with succinate. Ethylrhodamine staining and electron microscopic study reveal fragmentation of mitochondria in living cells
Circular photogalvanic effect induced by monopolar spin orientation in p-GaAs/AlGaAs MQW
The circular photogalvanic effect (CPGE) has been observed in (100)-oriented
-GaAs/AlGaAs quantum wells at normal incidence of far-infrared radiation. It
is shown that monopolar optical spin orientation of free carriers causes an
electric current which reverses its direction upon changing from left to right
circularly polarized radiation. CPGE at normal incidence and the occurence of
the linear photogalvanic effect indicate a reduced point symmetry of studied
multi-layered heterostructures. As proposed, CPGE can be utilized to
investigate separately spin polarization of electrons and holes and the
symmetry of quantum wells.Comment: 4 pages, 3 figure
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Microvesicles and intercellular communication in the context of parasitism
There is a rapidly growing body of evidence that production of microvesicles (MVs) is a universal feature of cellular life. MVs can incorporate microRNA (miRNA), mRNA, mtDNA, DNA and retrotransposons, camouflage viruses/viral components from immune surveillance, and transfer cargo between cells. These properties make MVs an essential player in intercellular communication. Increasing evidence supports the notion that MVs can also act as long-distance vehicles for RNA molecules and participate in metabolic synchronization and reprogramming eukaryotic cells including stem and germinal cells. MV ability to carry on DNA and their general distribution makes them attractive candidates for horizontal gene transfer, particularly between multi-cellular organisms and their parasites; this suggests important implications for the co-evolution of parasites and their hosts. In this review, we provide current understanding of the roles played by MVs in intracellular pathogens and parasitic infections. We also discuss the possible role of MVs in co-infection and host shifting
Automated image segmentation for detecting cell spreading for metastasizing assessments of cancer development
The automated segmentation of cells in microscopic images is an open research
problem that has important implications for studies of the developmental and
cancer processes based on in vitro models. In this paper, we present the
approach for segmentation of the DIC images of cultured cells using G-neighbor
smoothing followed by Kauwahara filtering and local standard deviation approach
for boundary detection. NIH FIJI/ImageJ tools are used to create the ground
truth dataset. The results of this work indicate that detection of cell
boundaries using segmentation approach even in the case of realistic
measurement conditions is a challenging problem
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