The photoluminescence of
GaAs
AlAs
multiple quantum wells structures under optical ps excitation is investigated for carrier densities in the range 10
18−4 × 10
19 cm
−3 with frequency and ...time-resolved spectroscopic techniques. The measurements give a direct evidence of the occurrence in the sample of carrier heating. This energy up-conversion gives rise to photoluminescence from the states near the Fermi level whose intensity and time evolution depend on the carrier density in a strongly non-linear way. The observed behaviour can be explained introducing in the carrier dynamics an up-conversion mechanism due to Auger-like processes.
Multipass automata and group word problems Ceccherini-Silberstein, Tullio; Coornaert, Michel; Fiorenzi, Francesca ...
arXiv (Cornell University),
07/2015
Paper, Journal Article
Odprti dostop
We introduce the notion of multipass automata as a generalization of pushdown automata and study the classes of languages accepted by such machines. The class of languages accepted by deterministic ...multipass automata is exactly the Boolean closure of the class of deterministic context-free languages while the class of languages accepted by nondeterministic multipass automata is exactly the class of poly-context-free languages, that is, languages which are the intersection of finitely many context-free languages. We illustrate the use of these automata by studying groups whose word problems are in the above classes.
The carrier dynamics of a
GaAs
AlAs
multiple quantum well is studied with a ps time-resolved excitation correlation spectroscopy (TREC). The measured TREC spectra can be reproduced by means of a ...simple model that takes into account the non-linearities of the dynamics.
The aim of the study was to verify whether the combination of an antiserotoninergic, metoclopramide, and a steroid could improve the complete control (CC) of delayed emesis, a contraversial issue, ...105 patients undergoing highly-emetogenic chemotherapy, receiving Ondansetron (O) 8 mg + Dexamethasone 20 mg i.v. for the prevention of acute emesis, were randomly treated p.o for three further days with a) Metoclopramide 10 mg x 3 b) the same as a) + Methylprednisolone 4 mg c) the same as b) + O 8 mg x 3. CC (acute+delayed emesis) over three cycles was: a) 0.b) 12.5%, c) 38.5% (p = 0.02). Days with nausea/vomiting: 59%, 51%, 29.7% of the total observed period, respectively (b vs c p = 0.0000). CC of acute emesis was similar in the first cycle (about 85%), remained unchanged in the following cycles (c) and decreased to 30% and 68% in the third cycle (a and b) (p = 0.01). The three drug combination significantly improved complete control of acute and delayed emesis over successive chemotherapy cycles.
We investigated mutations of the ret proto‐oncogene in Japanese patients with multiple endocrine neoplasia (MEN) type 2A and type 2B. DNAs from pheochromocytomas and/or medullary thyroid carcinomas ...(MTCs) of five MEN 2A and three MEN 2B patients were amplified by a polymerase chain reaction (PCR) and analyzed. Tumors of four MEN 2A patients had missense mutations in Cys 634 in the extracellular domain of the ret proto‐oncogene. The same mutations were detected in normal tissues of the patients, indicating that the mutations had arisen in the germ line. Using a reverse transcriptase(RT)‐PCR, both normal and mutant transcripts of the ret proto‐oncogene were detected in a tumor of one patient with MEN 2A mutation. In addition, three MEN 2B patients examined had the same point mutation (ATGÂG) at codon 918 in the tyrosine kinase domain of the ret proto‐oncogene. Since all mutations identified in this study generated new restriction enzyme sites or eliminated a restriction site, the mutant alleles of affected family members could be readily detected without sequencing.
Human T-cell leukemia--lymphoma virus (HTLV) is a type C retrovirus associated with a subtype of mature T-cell malignancy in humans. HTLV also infects normal human cord blood mature T lymphocytes in ...vitro and induces a number of phenotypic changes in these cells, including their continuous growth and partial or complete independence of T-cell growth factor (TCGF). As part of our initial study designed to analyze gene(s) specifically activated by HTLV infection, we have isolated a recombinant DNA clone by differential screening of a cDNA library made from mRNA of a human T-cell lymphoma cell line producing HTLV. This cDNA identifies a single-copy gene in all human DNAs and a single mRNA species of 2.3 kilobases expressed at several hundred copies per cell in five HTLV-positive neoplastic T-cell lines. In addition, cord blood T lymphocytes infected with HTLV, but not the uninfected counterparts, express high levels of mRNA from this gene. A survey of different human hematopoietic cell types showed that this gene is expressed at low or undetectable levels (<10 copies) in human T, B, myeloid, or erythroid cell lines; in moderate amounts in lymphoid precursor (immature) cell lines; and in high amounts in lectin-activated mature T-cells, comparable to those of HTLV-infected T-cell lines. The precise function of this gene has not yet been determined.
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