981 research outputs found

    Astrophysical constraints on the proton-to-electron mass ratio with FAST

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    That the laws of physics are the same at all times and places throughout the Universe is one of the basic assumptions of physics. Astronomical observations provide the only means to test this basic assumption on cosmological time and distance scales. The possibility of variations in the dimensionless physical constant {\mu} - the proton-to-electron mass ratio, can be tested by comparing astronomical measurements of the rest frequency of certain spectral lines at radio wavelengths with laboratory determinations. Different types of molecular transitions have different dependencies on {\mu} and so observations of two or more spectral lines towards the same astronomical source can be used to test whether there is any evidence for either temporal or spatial changes in the physical fundamental constants. {\mu} will change if the relative strength of the strong nuclear force compared to the electromagnetic force varies. Theoretical studies have shown that the rotational transitions of some molecules which have transitions in the frequency range that will be covered by FAST (e.g., CH3OH, OH and CH) are sensitive to changes in {\mu}. A number of studies looking for possible variations in {\mu} have been undertaken with existing telescopes, however, the greater sensitivity of FAST means it will open new opportunities to significantly improve upon measurements made to date. In this paper, we discuss which molecular transitions and sources (both in the Galaxy and external galaxies) are likely targets for providing improved constraints on {\mu} with FAST

    Amending coherence-breaking channels via unitary operations

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    The coherence-breaking channels play a significant role in quantum information theory. We study the coherence-breaking channels and give a method to amend the coherence-breaking channels by applying unitary operations. For given incoherent channel Φ\Phi, we give necessary and sufficient conditions for the channel to be a coherence-breaking channel and amend it via unitary operations. For qubit incoherent channels Φ\Phi that are not coherence-breaking ones, we consider the mapping ΦΦ\Phi\circ\Phi and present the conditions for coherence-breaking and channel amendment as well.Comment: 8 page

    The correlation between the plasma concentration of gemcitabine and short-term efficacy and adverse reactions in patients with advanced squamous cell carcinoma of the lung using liquid chromatography-mass spectrometry

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    AbstractBackground: Worldwide, non-small cell lung cancers have the highest incidence and mortality rates of all cancers. Gemcitabine (2’,2’-difluoro-2’-deoxycytidine or dFdC, C9H11F2N304) is widely used as the first-line chemo-reagent for lung cancer patients whose tumors have been diagnosed to be at an advanced stage and are therefore unresectable. Objective: The objective of this systematic study was to establish the correlation between the plasma concentration of gemcitabine and short-term clinical efficacy and adverse reactions in patients with advanced squamous cell carcinoma of the lung using liquid chromatography-mass spectrometry. Material and methods: In total, 53 patients were given the chemotherapy medications, gemcitabine and cisplatin, every 3 weeks. Plasma concentrations of gemcitabine were determined using liquid chromatography-mass spectrometry. A modified methodology of the liquid chromatography-mass spectrometry system was verified and performed to detect plasma concentrations of gemcitabine. The clinical endpoints – short-term clinical efficacy and adverse reactions – were evaluated after two cycles. Results: The plasma concentration range of gemcitabine in 53 patients was 1.58-28.70μg/ml (mean 14.37±8.63μg/ml), with 28 patients in the >15μg/ml group (mean 21.76±3.45μg/ml), and 25 patients in the ≤15μg/ml group (mean 6.09±3.57μg/ml). The clinical benefit rate (CBR) of the >15μg/ml group was significantly higher than that of the 15μg/ml group (p<0.05). The incidences of leukopenia and neutropenia, thrombocytopenia and grade III-IV gastrointestinal reactions in the >15μg/ml group were significantly higher than in the ≤15μg/ml group (p<0.05). There was no statistical difference between the two groups in terms of the incidences of reduced hemoglobin, liver and kidney function damage, allergic reaction and rash (p>0.05). The analysis of the plasma concentration of gemcitabine and the percentage of reduction in neutrophil count (NEUT) (r2 = 0.3212; p<0.05) and platelet (PLT) (r2 = 0.6439; p<0.05) showed a significant positive correlation. Conclusions: In patients with advanced non-small cell lung cancer, a high plasma concentration of gemcitabine can improve the short-term clinical efficacy of treatment, but increase the incidence of grade III-IV adverse reactions. [Ethiop. J. Health Dev. 2021; 35(1):72-82] Key words: Non-small cell lung cancer, gemcitabine, plasma concentration, short-term efficacy, adverse reaction

    Dermaseptin-PH: A Novel Peptide with Antimicrobial and Anticancer Activities from the Skin Secretion of the South American Orange-Legged Leaf Frog, Pithecopus (Phyllomedusa) hypochondrialis

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    The dermaseptin peptides, mainly derived from the skin secretions of Hylidae frogs, belong to a superfamily of antimicrobial peptides and exhibit diverse antimicrobial and anticancer activities with low cytotoxicity. Here, we reported a novel dermaseptin peptide, from the South American orange-legged leaf frogs, Pithecopus (Phyllomedusa) hypochondrialis, processing the shortest peptide length, namely Dermaseptin-PH. The complementary DNA (cDNA) encoding biosynthetic precursor of Dermaseptin-PH was initially identified by the rapid amplification of cDNA ends PCR (RACE-PCR) technique from the skin secretion. The predicted primary structure was confirmed by a combination of reverse-phase high performance liquid chromatography (RP-HPLC) and MS/MS fragmentation from the skin secretion. Chemically-synthetic Dermaseptin-PH was investigated using a range of bioactivity assessment assays to evaluate the biological activities and cytotoxicity of Dermaseptin-PH. Dermaseptin-PH inhibited the growth of Gram-negative bacteria, Gram-positive bacteria, and pathogenic yeast Candida albicans. In addition, Dermaseptin-PH showed a broad-spectrum of anticancer activities against several cancer cell lines including MCF-7, H157, U251MG, MDA-MB-435S, and PC-3. The potent antimicrobial and anticancer activities of Dermaseptin-PH make it a promising candidate in the discovery of new drugs for clinical applications, and the relatively short sequence of Dermaseptin-PH can provide new insight for the research and structural modification of new peptide drugs

    Exploring the Molecular and Metabolic Factors Contributing to the Adaptation of Maize Seedlings to Nitrate Limitation

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    Crop production on soils containing sub-optimal levels of nitrogen (N) severely compromises yield potential. The development of plant varieties displaying high N use efficiency (NUE) will optimize N fertilizer use and reduce the environmental damage caused by excess N application. Maize is one of the most important crops cultivated worldwide. Identification of the genotypes with an enhanced NUE in the field is both time and resource consuming and sometime is difficult due to the regulation in the biotechnology programs. Identification of traits associated with adaptation to N limitation at an early vegetative stage which could reflect NUE at maturity is in need. We developed a hydroponic growth system and used it to test two genotypes that were different in their NUE at maturity under N limitation. One genotype SRG-200 showed a higher NUE than the other genotype SRG-100 and we used its hybrid SRG-150 as a reference for NUE. A number of phenotypic, molecular, and metabolic factors were tested using these three genetic lines at an early vegetative stage to determine which of these could be more indicative of predicting improved NUE at an early seedling stage. These include a transcriptional analysis which showed that the higher NUE in SRG-200 genotype is associated with higher transcript levels for the genes involved in nitrate transport, N assimilation, and GS and that the SRG-200 genotype maintained higher sugar content in leaves. Those identified in this study could be useful indicators for selecting promising maize lines at early stages to help develop elite varieties showing an enhanced NUE

    Representation and measurement of the beam health based on one-dimensional model

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    This paper proposes a method for online structural health evaluation, and analyzes the correlation between online monitoring data and structural health status. On the basis of this analysis, the structural health can be evaluated by using the deviation of the current status from the initially designed status. The health degree index, representation and measurement models are also defined for structural health evaluation in this work. A numerical case study is conducted to validate the related concept and health evaluation model using a beam under pressure loads. The results indicate that the proposed method can effectively represent the structural health status

    Quantum Fisher information-based detection of genuine tripartite entanglement

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    Genuine multipartite entanglement plays important roles in quantum information processing. The detection of genuine multipartite entanglement has been long time a challenging problem in the theory of quantum entanglement. We propose a criterion for detecting genuine tripartite entanglement of arbitrary dimensional tripartite states based on quantum Fisher information. We show that this criterion is more effective for some states in detecting genuine tripartite entanglement by detailed example.Comment: 12 pages, 2 figure
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