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排序方式: 共有412条查询结果,搜索用时 15 毫秒
91.
Normal gastrointestinal function relies on sensing and transducing mechanical signals into changes in intracellular signaling pathways. Both specialized mechanosensing cells, such as certain enterochromaffin cells and enteric neurons, and non-specialized cells, such as smooth muscle cells, interstitial cells of Cajal, and resident macrophages, participate in physiological and pathological responses to mechanical signals in the gastrointestinal tract. We review the role of mechanosensors in the different cell types of the gastrointestinal tract. Then, we provide several examples of the role of mechanotransduction in normal physiology. These examples highlight the fact that, although these responses to mechanical signals have been known for decades, the mechanosensors involved in these responses to mechanical signals are largely unknown. Finally, we discuss several diseases involving the overstimulation or dysregulation of mechanotransductive pathways. Understanding these pathways and identifying the mechanosensors involved in these diseases may facilitate the identification of new drug targets to effectively treat these diseases. 相似文献
92.
Driver distraction is a factor that is heavily involved in traffic crashes. With in-vehicle devices like navigation systems or mobile phones on the rise, the assessment of their potential to distract the driver has become a pressing issue. Several easy-to-use methods have been developed in recent years to allow for such an assessment in the early stages of product development. One of these methods is the lane change task (LCT), a simple driving simulation in which the driver has to change lanes as indicated by different signs along the road. Although the LCT is an ISO sanctioned procedure, there are still open questions. One issue are learning effects which have been found in previous studies and which have the potential to compromise the comparability of test results. In this paper, we present results on two experiments that further explored the effect of previous experience on LCT and secondary task performance. The results confirm that learning effects occur when combining the LCT with a realistic secondary task. Also, we found evidence for the transfer of learning from one secondary task to another to some degree, provided that the two tasks are sufficiently similar. 相似文献
93.
Tibor Fegyó Máté Szarvas Péter Tatai Géza Gordos 《International Journal of Speech Technology》2000,3(3-4):277-287
This article describes an objective speech quality assessment method developed for the Hungarian NMT-450 cellular mobile telephone system. The method is based on a psychoacoustic front end followed by a cognitive modeling component. Special problems of the NMT system, such as handover (HOV), the effects of automatic gain control (AGC), and the intrusion of signaling noise, are addressed in the cognitive module. Correlation between the subjective and objective quality measures is maximized by finding a transformation that linearizes their relationship. A correlation of 0.95 is achieved on an independent test set between the subjective speech quality and the proposed objective quality measure. 相似文献
94.
Tibor Jordán 《Information Processing Letters》2012,112(8-9):356-359
We show that every 7-vertex-connected molecular graph is generically rigid in three dimensions. This verifies a special case of a conjecture of Lovász and Yemini. For this family of graphs the bound is best possible. 相似文献
95.
96.
Uwe Schlink Alexander Thiem Tibor Kohajda Matthias Richter Kathrin Strebel 《The Science of the total environment》2010,408(18):3840-3851
There are many factors determining the concentration of volatile organic compounds (VOCs) in indoor air. On the basis of 601 population-based measurements we develop an explicit exposure model that includes factors, such as renovation, furniture, flat size, smoking, and education level of the occupants.As a novel method for the evaluation of concentrations of indoor air pollutants we use quantile regression, which has the advantages of robustness against non-Gaussian distributions (and outliers) and can adjust for unbalanced frequencies of observations. The applied bi- and multivariate quantile regressions provide (1) the VOC burden that is representative for the population of Leipzig, Germany, and (2) an inter-comparison of the effects of the studied factors and their levels.As a result, we find strong evidence for factors of general impact on most VOC components, such as the season, flooring, the type of the room, and the size of the apartment. Other impact factors are very specific to the VOC components. For example, wooden flooring (parquet) and new furniture increase the concentration of terpenes as well as the modifying factors high education and sampling in the child's room. Smokers ventilate their flats in an extent that in general reduces the VOC concentrations, except for benzene (contained in tobacco smoke), which is still higher in smoking than in non-smoking flats. Very often dampness is associated with an increased VOC burden in indoor air.An investigation of mixtures emphasises a high burden of co-occurring terpenes in very small and very large apartments. 相似文献
97.
Comprehensive Two‐Dimensional Gas Chromatography–Mass Spectrometry Analysis of Different Types of Vegetable Oils 下载免费PDF全文
Olga Vyviurska Nikoleta Jánošková Tibor Jakubík Ivan Špánik 《Journal of the American Oil Chemists' Society》2015,92(6):783-790
Comprehensive two‐dimensional gas chromatography coupled with time‐of‐flight mass spectrometry (GC×GC‐TOFMS) was applied for detailed characterization of fatty acid profile of 8 vegetable oils. Due to enhanced selectivity and sensitivity characteristics, the GC×GC method yielded more reliable quantification results compared to one dimensional gas chromatography, especially for medium‐chain fatty acids and odd‐carbon number fatty acids, which are present only at trace level. All problematic positional counterparts of unsaturated fatty acids (e.g. C21:0–C20:3 ω6, C20:3ω3–C20:4 ω6 and C20:5 ω3–C22:0), which commonly coeluted in the case of 1D gas chromatography, were baseline resolved. The specific compounds were found for particular vegetable oils, such as γ‐linolenic acid for hempseed oil, heneicosylic acid and tricosylic acid for olive pomace oil, and nervonic acid for mustard oil. 相似文献
98.
Tibor Ajtai Ágnes Filep Martin Schnaiter Claudia Linke Marlen Vragel Zoltán Bozóki Gábor Szabó Thomas Leisner 《Journal of aerosol science》2010,41(11):1020-1029
A multi-wavelength photoacoustic instrument is described, which measures the wavelength dependent optical absorption coefficient (OAC) of soot or soot-containing aerosols in-situ in a range from the ultra-violet to the near-infrared region. The instrument combines a Nd:YAG disc laser (fundamental wavelength 1064 nm, harmonics at 532, 355 and 266 nm) and four photoacoustic detection cells, each purged with the same aerosol sample flow, while being irradiated with one of the four light beams. With the help of a supplementary optical arrangement to illuminate each detection cell with 532 nm light, the system is calibrated against OAC by purging the cells with known concentrations (and hereby known OAC values) of NO2. This calibration eliminates differences in sensitivity of the detection PA cells and makes the measurement of OAC absolute.The minimum detectable OAC was determined to be 0.2 Mm?1 at 1064 nm and 35.5 Mm?1 at 266 nm, corresponding to a minimum detectable black carbon mass concentration of about 0.1–1 μg/m3, depending on the wavelength. Comparison measurements with artificially generated soot aerosols showed good agreement of the device with a reference instrument, based on a long path extinction cell (LOPES). 相似文献
99.
Periša Marko Kuljanić Tibor Mijo Cvitić Ivan Kolarovszki Peter 《Wireless Networks》2021,27(3):1615-1626
Wireless Networks - The everyday needs of people with disabilities represent a challenge in designing new and innovative services. The capabilities provided by modern communication technologies... 相似文献
100.
Sylva Prerostova Petre I. Dobrev Vojtech Knirsch Jana Jarosova Alena Gaudinova Barbara Zupkova Ilja T. Pril Tibor Janda Betislav Brzobohatý Jan Skalk Radomira Vankova 《International journal of molecular sciences》2021,22(5)
Plant survival in temperate zones requires efficient cold acclimation, which is strongly affected by light and temperature signal crosstalk, which converge in modulation of hormonal responses. Cold under low light conditions affected Arabidopsis responses predominantly in apices, possibly because energy supplies were too limited for requirements of these meristematic tissues, despite a relatively high steady-state quantum yield. Comparing cold responses at optimal light intensity and low light, we found activation of similar defence mechanisms—apart from CBF1–3 and CRF3–4 pathways, also transient stimulation of cytokinin type-A response regulators, accompanied by fast transient increase of trans-zeatin in roots. Upregulated expression of components of strigolactone (and karrikin) signalling pathway indicated involvement of these phytohormones in cold responses. Impaired response of phyA, phyB, cry1 and cry2 mutants reflected participation of these photoreceptors in acquiring freezing tolerance (especially cryptochrome CRY1 at optimal light intensity and phytochrome PHYA at low light). Efficient cold acclimation at optimal light was associated with upregulation of trans-zeatin in leaves and roots, while at low light, cytokinin (except cis-zeatin) content remained diminished. Cold stresses induced elevation of jasmonic acid and salicylic acid (in roots). Low light at optimal conditions resulted in strong suppression of cytokinins, jasmonic and salicylic acid. 相似文献