Artículos de revistas sobre el tema "Rolling PMF"
Siga este enlace para ver otros tipos de publicaciones sobre el tema: Rolling PMF.
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte los 50 mejores artículos de revistas para su investigación sobre el tema "Rolling PMF".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Explore artículos de revistas sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.
1
Via, Marta, Gang Chen, Francesco Canonaco, Kaspar R. Daellenbach, Benjamin Chazeau, Hasna Chebaicheb, Jianhui Jiang et al. "Rolling vs. seasonal PMF: real-world multi-site and synthetic dataset comparison". Atmospheric Measurement Techniques 15, n.º 18 (27 de septiembre de 2022): 5479–95. http://dx.doi.org/10.5194/amt-15-5479-2022.
Texto completoResumen
Abstract. Particulate matter (PM) has become a major concern in terms of human health and climate impact. In particular, the source apportionment (SA) of organic aerosols (OA) present in submicron particles (PM1) has gained relevance as an atmospheric research field due to the diversity and complexity of its primary sources and secondary formation processes. Moreover, relatively simple but robust instruments such as the Aerosol Chemical Speciation Monitor (ACSM) are now widely available for the near-real-time online determination of the composition of the non-refractory PM1. One of the most used tools for SA purposes is the source-receptor positive matrix factorisation (PMF) model. Even though the recently developed rolling PMF technique has already been used for OA SA on ACSM datasets, no study has assessed its added value compared to the more common seasonal PMF method using a practical approach yet. In this paper, both techniques were applied to a synthetic dataset and to nine European ACSM datasets in order to spot the main output discrepancies between methods. The main advantage of the synthetic dataset approach was that the methods' outputs could be compared to the expected “true” values, i.e. the original synthetic dataset values. This approach revealed similar apportionment results amongst methods, although the rolling PMF profile's adaptability feature proved to be advantageous, as it generated output profiles that moved nearer to the truth points. Nevertheless, these results highlighted the impact of the profile anchor on the solution, as the use of a different anchor with respect to the truth led to significantly different results in both methods. In the multi-site study, while differences were generally not significant when considering year-long periods, their importance grew towards shorter time spans, as in intra-month or intra-day cycles. As far as correlation with external measurements is concerned, rolling PMF performed better than seasonal PMF globally for the ambient datasets investigated here, especially in periods between seasons. The results of this multi-site comparison coincide with the synthetic dataset in terms of rolling–seasonal similarity and rolling PMF reporting moderate improvements. Altogether, the results of this study provide solid evidence of the robustness of both methods and of the overall efficiency of the recently proposed rolling PMF approach.
2
Lin, Chunshui, Darius Ceburnis, Colin O’Dowd y Jurgita Ovadnevaite. "Seasonality of Aerosol Sources Calls for Distinct Air Quality Mitigation Strategies". Toxics 10, n.º 3 (3 de marzo de 2022): 121. http://dx.doi.org/10.3390/toxics10030121.
Texto completoResumen
An Aerosol Chemical Speciation Monitor (ACSM) was deployed to investigate the temporal variability of non-refractory particulate matter (NR-PM1) in the coastal city of Galway, Ireland, from February to July 2016. Source apportionment of the organic aerosol (OA) was performed using the newly developed rolling PMF strategy and was compared with the conventional seasonal PMF. Primary OA (POA) factors apportioned by rolling and seasonal PMF were similar. POA factors of hydrocarbon-like OA (HOA), peat, wood, and coal were associated with domestic heating, and with an increased contribution to the OA mass in winter. Even in summer, sporadic heating events occurred with similar diurnal patterns to that in winter. Two oxygenated OA (OOA) factors were resolved, including more-oxygenated OOA and less-oxygenated OOA (i.e., MO-OOA and LO-OOA, accordingly) which were found to be the dominant OA factors during summer. On average, MO-OOA accounted for 62% of OA and was associated with long-range transport in summer. In summer, compared to rolling PMF, the conventional seasonal PMF over-estimated LO-OOA by nearly 100% while it underestimated MO-OOA by 30%. The results from this study show residential heating and long-range transport alternately dominate the submicron aerosol concentrations in this coastal city, requiring different mitigation strategies in different seasons.
3
Wang, Qiongqiong, Shuhui Zhu, Shan Wang, Cheng Huang, Yusen Duan y Jian Zhen Yu. "Short-term source apportionment of fine particulate matter with time-dependent profiles using SoFi Pro: exploring the reliability of rolling positive matrix factorization (PMF) applied to bihourly molecular and elemental tracer data". Atmospheric Chemistry and Physics 24, n.º 1 (12 de enero de 2024): 475–86. http://dx.doi.org/10.5194/acp-24-475-2024.
Texto completoResumen
Abstract. Positive matrix factorization (PMF) has been widely used to apportion the sources of fine particulate matter (PM2.5) by utilizing PM chemical speciation data measured at the receptor site(s). Traditional PMF, which typically relies on long-term observational datasets of daily or lower time resolution to meet the required sample size, has its reliability undermined by changes in source profiles; thus, it is inherently ill-suited for apportioning sporadic sources or ephemeral pollution events. In this study, we explored short-term source apportionment of PM2.5 using a set of bihourly chemical speciation data over a period of 37 d in the winter of 2019–2020. PMF run with campaign-wide data as input (PMFref) was initially conducted to obtain reference profiles for the primary source factors. Subsequently, short-term PMF analysis was performed using the Source Finder Professional (SoFi Pro). The analysis sets a window length of 18 d and constrained the primary source profiles using the a-value approach embedded in SoFi Pro software. Rolling PMF was then conducted with a fixed window length of 18 d and a step of 1 d using the remaining dataset. By applying the a-value constraints to the primary sources, the rolling PMF effectively reproduced the individual primary sources, as evidenced by the slope values close to unity (i.e., 0.9–1.0). However, the estimation for the firework emission factor in the rolling PMF was lower compared with PMFref (slope: 0.8). These results suggest the unique advantage of short-term PMF analysis in accurately apportioning sporadic sources. Although the total secondary sources were well modeled (slope: 1.0), larger biases were observed for individual secondary sources. The variation in source profiles indicated higher variabilities for the secondary sources, with average relative differences ranging from 42 % to 173 %, while the primary source profiles exhibited much smaller variabilities (relative differences of 8 %–26 %). This study suggests that short-term PMF analysis with the a-value constraints in SoFi Pro can be utilized to apportion primary sources accurately, while future efforts are needed to improve the prediction of individual secondary sources. Additionally, future rapid source apportionment analysis can benefit from utilizing a library of source profiles derived from existing measurement data, thereby significantly reducing the time lag associated with receptor modeling source apportionment techniques.
4
Chen, Gang, Yulia Sosedova, Francesco Canonaco, Roman Fröhlich, Anna Tobler, Athanasia Vlachou, Kaspar R. Daellenbach et al. "Time-dependent source apportionment of submicron organic aerosol for a rural site in an alpine valley using a rolling positive matrix factorisation (PMF) window". Atmospheric Chemistry and Physics 21, n.º 19 (11 de octubre de 2021): 15081–101. http://dx.doi.org/10.5194/acp-21-15081-2021.
Texto completoResumen
Abstract. We collected 1 year of aerosol chemical speciation monitor (ACSM) data in Magadino, a village located in the south of the Swiss Alpine region, one of Switzerland's most polluted areas. We analysed the mass spectra of organic aerosol (OA) by positive matrix factorisation (PMF) using Source Finder Professional (SoFi Pro) to retrieve the origins of OA. Therein, we deployed a rolling algorithm, which is closer to the measurement, to account for the temporal changes in the source profiles. As the first-ever application of rolling PMF with multilinear engine (ME-2) analysis on a yearlong dataset that was collected from a rural site, we resolved two primary OA factors (traffic-related hydrocarbon-like OA (HOA) and biomass burning OA (BBOA)), one mass-to-charge ratio (m/z) 58-related OA (58-OA) factor, a less oxidised oxygenated OA (LO-OOA) factor, and a more oxidised oxygenated OA (MO-OOA) factor. HOA showed stable contributions to the total OA through the whole year ranging from 8.1 % to 10.1 %, while the contribution of BBOA showed an apparent seasonal variation with a range of 8.3 %–27.4 % (highest during winter, lowest during summer) and a yearly average of 17.1 %. OOA (sum of LO-OOA and MO-OOA) contributed 71.6 % of the OA mass, varying from 62.5 % (in winter) to 78 % (in spring and summer). The 58-OA factor mainly contained nitrogen-related variables which appeared to be pronounced only after the filament switched. However, since the contribution of this factor was insignificant (2.1 %), we did not attempt to interpolate its potential source in this work. The uncertainties (σ) for the modelled OA factors (i.e. rotational uncertainty and statistical variability in the sources) varied from ±4 % (58-OA) to a maximum of ±40 % (LO-OOA). Considering that BBOA and LO-OOA (showing influences of biomass burning in winter) had significant contributions to the total OA mass, we suggest reducing and controlling biomass-burning-related residential heating as a mitigation strategy for better air quality and lower PM levels in this region or similar locations. In Appendix A, we conduct a head-to-head comparison between the conventional seasonal PMF analysis and the rolling mechanism. We find similar or slightly improved results in terms of mass concentrations, correlations with external tracers, and factor profiles of the constrained POA factors. The rolling results show smaller scaled residuals and enhanced correlations between OOA factors and corresponding inorganic salts compared to those of the seasonal solutions, which was most likely because the rolling PMF analysis can capture the temporal variations in the oxidation processes for OOA components. Specifically, the time-dependent factor profiles of MO-OOA and LO-OOA can well explain the temporal viabilities of two main ions for OOA factors, m/z 44 (CO2+) and m/z 43 (mostly C2H3O+). Therefore, this rolling PMF analysis provides a more realistic source apportionment (SA) solution with time-dependent OA sources. The rolling results also show good agreement with offline Aerodyne aerosol mass spectrometer (AMS) SA results from filter samples, except for in winter. The latter discrepancy is likely because the online measurement can capture the fast oxidation processes of biomass burning sources, in contrast to the 24 h filter samples. This study demonstrates the strengths of the rolling mechanism, provides a comprehensive criterion list for ACSM users to obtain reproducible SA results, and is a role model for similar analyses of such worldwide available data.
5
Canonaco, Francesco, Anna Tobler, Gang Chen, Yulia Sosedova, Jay Gates Slowik, Carlo Bozzetti, Kaspar Rudolf Daellenbach et al. "A new method for long-term source apportionment with time-dependent factor profiles and uncertainty assessment using SoFi Pro: application to 1 year of organic aerosol data". Atmospheric Measurement Techniques 14, n.º 2 (8 de febrero de 2021): 923–43. http://dx.doi.org/10.5194/amt-14-923-2021.
Texto completoResumen
Abstract. A new methodology for performing long-term source apportionment (SA) using positive matrix factorization (PMF) is presented. The method is implemented within the SoFi Pro software package and uses the multilinear engine (ME-2) as a PMF solver. The technique is applied to a 1-year aerosol chemical speciation monitor (ACSM) dataset from downtown Zurich, Switzerland. The measured organic aerosol mass spectra were analyzed by PMF using a small (14 d) and rolling PMF window to account for the temporal evolution of the sources. The rotational ambiguity is explored and the uncertainties of the PMF solutions were estimated. Factor–tracer correlations for averaged seasonal results from the rolling window analysis are higher than those retrieved from conventional PMF analyses of individual seasons, highlighting the improved performance of the rolling window algorithm for long-term data. In this study four to five factors were tested for every PMF window. Factor profiles for primary organic aerosol from traffic (HOA), cooking (COA) and biomass burning (BBOA) were constrained. Secondary organic aerosol was represented by either the combination of semi-volatile and low-volatility organic aerosol (SV-OOA and LV-OOA, respectively) or by a single OOA when this separation was not robust. This scheme led to roughly 40 000 PMF runs. Full visual inspection of all these PMF runs is unrealistic and is replaced by predefined user-selected criteria, which allow factor sorting and PMF run acceptance/rejection. The selected criteria for traffic (HOA) and BBOA were the correlation with equivalent black carbon from traffic (eBCtr) and the explained variation of m/z 60, respectively. COA was assessed by the prominence of a lunchtime concentration peak within the diurnal cycle. SV-OOA and LV-OOA were evaluated based on the fractions of m/z 43 and 44 in their respective factor profiles. Seasonal pre-tests revealed a non-continuous separation of OOA into SV-OOA and LV-OOA, in particular during the warm seasons. Therefore, a differentiation between four-factor solutions (HOA, COA, BBOA and OOA) and five-factor solutions (HOA, COA, BBOA, SV-OOA and LV-OOA) was also conducted based on the criterion for SV-OOA. HOA and COA contribute between 0.4–0.7 µg m−3 (7.8 %–9.0 %) and 0.7–1.2 µg m−3 (12.2 %–15.7 %) on average throughout the year, respectively. BBOA shows a strong yearly cycle with the lowest mean concentrations in summer (0.6 µg m−3, 12.0 %), slightly higher mean concentrations during spring and fall (1.0 and 1.5 µg m−3, or 15.6 % and 18.6 %, respectively), and the highest mean concentrations during winter (1.9 µg m−3, 25.0 %). In summer, OOA is separated into SV-OOA and LV-OOA, with mean concentrations of 1.4 µg m−3 (26.5 %) and 2.2 µg m−3 (40.3 %), respectively. For the remaining seasons the seasonal concentrations of SV-OOA, LV-OOA and OOA range from 0.3 to 1.1 µg m−3 (3.4 %–15.9 %), from 0.6 to 2.2 µg m−3 (7.7 %–33.7 %) and from 0.9 to 3.1 µg m−3 (13.7 %–39.9 %), respectively. The relative PMF errors modeled for this study for HOA, COA, BBOA, LV-OOA, SV-OOA and OOA are on average ±34 %, ±27 %, ±30 %, ±11 %, ±25 % and ±12 %, respectively.
6
Yang, Xu, XianGuo Li, DeJun Meng, Jia Shi y ChangYun Miao. "Optical fiber vibration sensor for bearing fault detection based on Sagnac interferometer". Laser Physics 33, n.º 6 (13 de abril de 2023): 065101. http://dx.doi.org/10.1088/1555-6611/acca04.
Texto completoResumen
Abstract Bearings are crucial components in mechanical equipment, and bearing failure is one of the reasons for mechanical equipment safety accidents. In this work, an optical fiber vibration sensor based on Sagnac interferometer (SI) is proposed and applied to bearing fault detection. The polarization-maintaining fiber (PMF) is spliced between two single-mode fibers (SMFs) to form a SMF-PMF-SMF (SPS) fiber structure, which is connected with a 3 dB coupler to form a SI based on SPS fiber structure. The mass block is fixed in the middle of the PMF. When the monitored surface or structure vibrates, the stress of PMF will change and the Sagnac interference spectrum will be shifted, so that the vibration can be measured. The fabrication technology of sensor based on 3D printing is studied, and the structural parameters of the sensor are optimized through experiments and theoretical analysis. A vibration detection system and a rolling bearing vibration test platform based on SI and fiber ring laser are built. The experimental results show that the relative error between the experimental and theoretical results of healthy and faulty bearings is less than 1.60%, and the fault detection of bearings is realized. Temperature cross-sensitivity and stability of the sensing system are analyzed. The sensor has the advantages of simple structure, easy fabrication, anti-interference, etc, and has wide application prospects in engineering, machinery, security and other fields.
7
Zografou, Olga, Maria Gini, Manousos I. Manousakas, Gang Chen, Athina C. Kalogridis, Evangelia Diapouli, Athina Pappa y Konstantinos Eleftheriadis. "Combined organic and inorganic source apportionment on yearlong ToF-ACSM dataset at a suburban station in Athens". Atmospheric Measurement Techniques 15, n.º 16 (17 de agosto de 2022): 4675–92. http://dx.doi.org/10.5194/amt-15-4675-2022.
Texto completoResumen
Abstract. The current improvements in aerosol mass spectrometers in resolution and sensitivity, and the analytical tools for mass spectra deconvolution, have enabled the in-depth analysis of ambient organic aerosol (OA) properties. Although OA constitutes a major fraction of ambient aerosol, its properties are determined to a great extent by the mixing characteristics of both organic and inorganic components of ambient aerosol. This work applies a new methodology to a year-long ACSM dataset to assess the sources of organic and total non-refractory species in the Athens background aerosol and provides insights into the interactions between organic and inorganic species. The use of innovative tools for applying positive matrix factorization (PMF, rolling window) enables the study of the temporal variability of the contribution of these sources and seasonal changes in their composition. The mass spectra of both organic and inorganic aerosol were obtained by a time-of-flight aerosol mass spectrometer (ToF-ACSM) for PMF analysis. The results revealed five factors when organic aerosol was analysed separately. Three of them were primary OA factors: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA) and biomass burning organic aerosol (BBOA). The remaining two were secondary, less and more oxidized oxygenated organic aerosol (LO-OOA and MO-OOA respectively). The relative contributions of these factors were HOA 15 %, COA 18 %, BBOA 9 %, MO-OOA 34 % and LO-OOA 24 % (yearly averaged). When a combined organic and inorganic aerosol matrix was analysed, two additional factors were identified that were mainly composed of ammonium sulfate (83.5 %) and ammonium nitrate (73 %). Moreover, two secondary factors were resolved, containing both organics and inorganics and were named more (MOA) and less oxidized aerosol (LOA). The relative contributions on a yearly average of these factors were HOA 7 %, COA 9 %, BBOA 3 %, ammonium nitrate 3 %, ammonium sulfate 28 %, MOA 24 % and LOA 26 %.
8
Heikkinen, Liine, Mikko Äijälä, Kaspar R. Daellenbach, Gang Chen, Olga Garmash, Diego Aliaga, Frans Graeffe et al. "Eight years of sub-micrometre organic aerosol composition data from the boreal forest characterized using a machine-learning approach". Atmospheric Chemistry and Physics 21, n.º 13 (6 de julio de 2021): 10081–109. http://dx.doi.org/10.5194/acp-21-10081-2021.
Texto completoResumen
Abstract. The Station for Measuring Ecosystem–Atmosphere Relations (SMEAR) II, located within the boreal forest of Finland, is a unique station in the world due to the wide range of long-term measurements tracking the Earth–atmosphere interface. In this study, we characterize the composition of organic aerosol (OA) at SMEAR II by quantifying its driving constituents. We utilize a multi-year data set of OA mass spectra measured in situ with an Aerosol Chemical Speciation Monitor (ACSM) at the station. To our knowledge, this mass spectral time series is the longest of its kind published to date. Similarly to other previously reported efforts in OA source apportionment from multi-seasonal or multi-annual data sets, we approached the OA characterization challenge through positive matrix factorization (PMF) using a rolling window approach. However, the existing methods for extracting minor OA components were found to be insufficient for our rather remote site. To overcome this issue, we tested a new statistical analysis framework. This included unsupervised feature extraction and classification stages to explore a large number of unconstrained PMF runs conducted on the measured OA mass spectra. Anchored by these results, we finally constructed a relaxed chemical mass balance (CMB) run that resolved different OA components from our observations. The presented combination of statistical tools provided a data-driven analysis methodology, which in our case achieved robust solutions with minimal subjectivity. Following the extensive statistical analyses, we were able to divide the 2012–2019 SMEAR II OA data (mass concentration interquartile range (IQR): 0.7, 1.3, and 2.6 µg m−3) into three sub-categories – low-volatility oxygenated OA (LV-OOA), semi-volatile oxygenated OA (SV-OOA), and primary OA (POA) – proving that the tested methodology was able to provide results consistent with literature. LV-OOA was the most dominant OA type (organic mass fraction IQR: 49 %, 62 %, and 73 %). The seasonal cycle of LV-OOA was bimodal, with peaks both in summer and in February. We associated the wintertime LV-OOA with anthropogenic sources and assumed biogenic influence in LV-OOA formation in summer. Through a brief trajectory analysis, we estimated summertime natural LV-OOA formation of tens of ng m−3 h−1 over the boreal forest. SV-OOA was the second highest contributor to OA mass (organic mass fraction IQR: 19 %, 31 %, and 43 %). Due to SV-OOA's clear peak in summer, we estimate biogenic processes as the main drivers in its formation. Unlike for LV-OOA, the highest SV-OOA concentrations were detected in stable summertime nocturnal surface layers. Two nearby sawmills also played a significant role in SV-OOA production as also exemplified by previous studies at SMEAR II. POA, taken as a mix of two different OA types reported previously, hydrocarbon-like OA (HOA) and biomass burning OA (BBOA), made up a minimal OA mass fraction (IQR: 2 %, 6 %, and 13 %). Notably, the quantification of POA at SMEAR II using ACSM data was not possible following existing rolling PMF methodologies. Both POA organic mass fraction and mass concentration peaked in winter. Its appearance at SMEAR II was linked to strong southerly winds. Similar wind direction and speed dependence was not observed among other OA types. The high wind speeds probably enabled the POA transport to SMEAR II from faraway sources in a relatively fresh state. In the event of slower wind speeds, POA likely evaporated and/or aged into oxidized organic aerosol before detection. The POA organic mass fraction was significantly lower than reported by aerosol mass spectrometer (AMS) measurements 2 to 4 years prior to the ACSM measurements. While the co-located long-term measurements of black carbon supported the hypothesis of higher POA loadings prior to year 2012, it is also possible that short-term (POA) pollution plumes were averaged out due to the slow time resolution of the ACSM combined with the further 3 h data averaging needed to ensure good signal-to-noise ratios (SNRs). Despite the length of the ACSM data set, we did not focus on quantifying long-term trends of POA (nor other components) due to the high sensitivity of OA composition to meteorological anomalies, the occurrence of which is likely not normally distributed over the 8-year measurement period. Due to the unique and realistic seasonal cycles and meteorology dependences of the independent OA subtypes complemented by the reasonably low degree of unexplained OA variability, we believe that the presented data analysis approach performs well. Therefore, we hope that these results encourage also other researchers possessing several-year-long time series of similar data to tackle the data analysis via similar semi- or unsupervised machine-learning approaches. This way the presented method could be further optimized and its usability explored and evaluated also in other environments.
9
Atabakhsh, Samira, Laurent Poulain, Gang Chen, Francesco Canonaco, André S. H. Prévôt, Mira Pöhlker, Alfred Wiedensohler y Hartmut Herrmann. "A 1-year aerosol chemical speciation monitor (ACSM) source analysis of organic aerosol particle contributions from anthropogenic sources after long-range transport at the TROPOS research station Melpitz". Atmospheric Chemistry and Physics 23, n.º 12 (23 de junio de 2023): 6963–88. http://dx.doi.org/10.5194/acp-23-6963-2023.
Texto completoResumen
Abstract. Atmospheric aerosol particles are a complex combination of primary emitted sources (biogenic and anthropogenic) and secondary aerosol resulting from aging processes such as condensation, coagulation, and cloud processing. To better understand their sources, investigations have been focused on urban areas in the past, whereas rural-background stations are normally less impacted by surrounding anthropogenic sources. Therefore, they are predisposed for studying the impact of long-range transport of anthropogenic aerosols. Here, the chemical composition and organic aerosol (OA) sources of submicron aerosol particles measured by an aerosol chemical speciation monitor (ACSM) and a multi-angle absorption photometer (MAAP) were investigated at Melpitz from September 2016 to August 2017. The location of the station at the frontier between western and eastern Europe makes it the ideal place to investigate the impact of long-range transport over Europe. Indeed, the station is under the influence of less polluted air masses from westerly directions and more polluted continental air masses from eastern Europe. The OA dominated the submicron particle mass concentration and showed strong seasonal variability ranging from 39 % (in winter) to 58 % (in summer). It was followed by sulfate (15 % and 20 %) and nitrate (24 % and 11 %). The OA source identification was performed using the rolling positive matrix factorization (PMF) approach to account for the potential temporal changes in the source profile. It was possible to split OA into five factors with a distinct temporal variability and mass spectral signature. Three were associated with anthropogenic primary OA (POA) sources: hydrocarbon-like OA (HOA; 5.2 % of OA mass in winter and 6.8 % in summer), biomass burning OA (BBOA; 10.6 % and 6.1 %) and coal combustion OA (CCOA; 23 % and 8.7 %). Another two are secondary and processed oxygenated OA (OOA) sources: less oxidized OOA (LO-OOA; 28.4 % and 36.7 %) and more oxidized OOA (MO-OOA; 32.8 % and 41.8 %). Since equivalent black carbon (eBC) was clearly associated with the identified POA factors (sum of HOA, BBOA, and CCOA; R2= 0. 87), eBC's contribution to each of the POA factors was achieved using a multilinear regression model. Consequently, CCOA represented the main anthropogenic sources of carbonaceous aerosol (sum of OA and eBC) not only during winter (56 % of POA in winter) but also in summer (13 % of POA in summer), followed by BBOA (29 % and 69 % of POA in winter and summer, respectively) and HOA (15 % and 18 % of POA in winter and summer, respectively). A seasonal air mass cluster analysis was used to understand the geographical origins of the different aerosol types and showed that during both winter and summer time, PM1 (PM with an aerodynamic diameter smaller than 1 µm) air masses with eastern influence were always associated with the highest mass concentration and the highest coal combustion fraction. Since during wintertime CCOA is a combination of domestic heating and power plant emissions, the summer contribution of CCOA emphasizes the critical importance of coal power plant emissions to rural-background aerosols and its impact on air quality, through long-range transportation.
10
SHINOHARA, T. y K. YOSHIDA. "PLF-13: Deformation Analysis of Surface Crack in Rolling and Wire Drawing(PLF-III: PLASTIC FORMING AND ADVANCED PRODUCTS)". Proceedings of the JSME Materials and Processing Conference (M&P) 2005 (2005): 39–40. http://dx.doi.org/10.1299/jsmeintmp.2005.39_6.
Texto completo
11
Zimmerman, B. J., J. W. Holt, J. C. Paulson, D. C. Anderson, M. Miyasaka, T. Tamatani, R. F. Todd, J. R. Rusche y D. N. Granger. "Molecular determinants of lipid mediator-induced leukocyte adherence and emigration in rat mesenteric venules". American Journal of Physiology-Heart and Circulatory Physiology 266, n.º 3 (1 de marzo de 1994): H847—H853. http://dx.doi.org/10.1152/ajpheart.1994.266.3.h847.
Texto completoResumen
The objective of this study was to identify the molecular determinants of leukocyte rolling, adherence, and emigration elicited in postcapillary venules by the lipid mediators leukotriene B4 (LTB4) or platelet-activating factor (PAF). Leukocyte-endothelial cell adhesion and shear rate were monitored in rat mesenteric venules during superfusion with either LTB4 or PAF in the presence or absence of monoclonal antibodies (MAbs) directed against either leukocyte (CD18, CD11b) or endothelial cell [intercellular adhesion molecule 1 (ICAM-1), E-selectin, P-selectin] adhesion glycoproteins. In untreated animals and in animals receiving a nonbinding control MAb, LTB4 and PAF increased the number of both adherent (8- and 4-fold, respectively) and emigrated (14- and 8-fold, respectively) leukocytes, while reducing leukocyte rolling velocity (36 and 33%, respectively). The LTB4- and PAF-induced leukocyte adherence and emigration were significantly attenuated by pretreatment with MAbs directed against CD18, CD11b, ICAM-1, and E-selectin, but not P-selectin. The reduction in leukocyte rolling velocity induced by LTB4 was not affected by any of the MAbs; however, both P- and E-selectin MAbs significantly attenuated the reduction in leukocyte rolling velocity elicited by PAF. The results of this study indicate that the leukocyte adherence and emigration induced by both LTB4 and PAF are mediated by CD11b/CD18 on leukocytes and by ICAM-1 and E-selectin on endothelial cells. The molecular determinant of leukocyte rolling appears to be mediator specific, with the selectins mediating the rolling elicited by PAF.
12
Gaboury, J. P., D. C. Anderson y P. Kubes. "Molecular mechanisms involved in superoxide-induced leukocyte-endothelial cell interactions in vivo". American Journal of Physiology-Heart and Circulatory Physiology 266, n.º 2 (1 de febrero de 1994): H637—H642. http://dx.doi.org/10.1152/ajpheart.1994.266.2.h637.
Texto completoResumen
Intravital microscopy was used to monitor leukocyte adherence, flux, rolling velocity, and number of rolling leukocytes (flux/velocity) in venules 25–40 microns in diameter. The superoxide-generating system, hypoxanthine and xanthine oxidase (HX/XO), was infused into the mesenteric circulation in untreated animals or in animals pretreated with either catalase (a hydrogen peroxide scavenger), WEB-2086 [a platelet-activating factor (PAF) receptor antagonist], or monoclonal antibodies directed against adhesion molecules CD18 (CL26) or P-selectin (PB1.3). HX/XO infusion caused a decrease in leukocyte rolling velocity and an increase in the number of rolling and adherent leukocytes. WEB-2086 prevented the increase in leukocyte adhesion and markedly increased leukocyte rolling velocity. PB1.3 abolished the HX/XO-associated rise in the flux of rolling leukocytes and proportionally decreased the number of adherent leukocytes. CL26 abolished HX/XO-induced leukocyte adhesion and also reduced the number of rolling leukocytes. In conclusion, P-selectin mediates the increased leukocyte flux induced by superoxide, whereas PAF and CD18 modulate leukocyte adhesion. PAF also reduces leukocyte rolling velocity, possibly as a result of CD18, but not P-selectin.
13
Hegyvári, Norbert y Gergely Wintsche. "The rolling polyhedra". Publicationes Mathematicae Debrecen 52, n.º 1-2 (1 de enero de 1998): 43–54. http://dx.doi.org/10.5486/pmd.1998.1741.
Texto completo
14
Macconi, D., M. Foppolo, S. Paris, M. Noris, S. Aiello, G. Remuzzi y A. Remuzzi. "PAF mediates neutrophil adhesion to thrombin or TNF-stimulated endothelial cells under shear stress". American Journal of Physiology-Cell Physiology 269, n.º 1 (1 de julio de 1995): C42—C47. http://dx.doi.org/10.1152/ajpcell.1995.269.1.c42.
Texto completoResumen
Platelet-activating factor (PAF) is known to modulate polymorphonuclear leukocyte (PMN) adhesion to endothelial cells cultured under static conditions and activated by thrombin. In contrast, there are no data on the role of PAF in PMN adhesion to cells exposed to flow conditions and activated by stimuli other than thrombin. Here we used the PAF receptor antagonist L-659,989 to evaluate PMN adhesion to human umbilical vein endothelial cells (HUVEC) in basal conditions or upon challenge with thrombin or tumor necrosis factor-alpha (TNF-alpha). Experiments were performed under dynamic flow using a parallel-plate flow chamber and a computer-based image analysis system. Rolling and adhesion of PMNs to endothelial cells significantly increased upon stimulation with thrombin. Thrombin-stimulated HUVEC also synthesized higher amounts of PAF than untreated cells. Pretreatment of PMNs with L-659,989 significantly reduced their rolling and adhesion to thrombin-activated HUVEC. Stimulation of HUVEC with TNF-alpha significantly increased the number of rolling and adherent PMNs as compared with untreated cells. Adhesion of PMNs to and migration across TNF-alpha-stimulated HUVEC were reduced by L-659,989, whereas cell rolling was unchanged. We conclude that PAF mediates leukocyte interaction under flow conditions with HUVEC activated by inflammatory stimuli.
15
Mayer, Konstantin, Martina Merfels, Marion Muhly-Reinholz, Stephanie Gokorsch, Simone Rosseau, Jürgen Lohmeyer, Nicole Schwarzer et al. "ω-3 Fatty acids suppress monocyte adhesion to human endothelial cells: role of endothelial PAF generation". American Journal of Physiology-Heart and Circulatory Physiology 283, n.º 2 (1 de agosto de 2002): H811—H818. http://dx.doi.org/10.1152/ajpheart.00235.2002.
Texto completoResumen
Monocyte-endothelium interaction is a fundamental process in many acute and chronic inflammatory diseases. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are fish oil-derived alternative (ω-3) precursor fatty acids implicated in the suppression of inflammatory events. We investigated their influence on rolling and adhesion of monocytes to human umbilical vein endothelial cells (HUVEC) under laminar flow conditions in vitro. Exposure of HUVEC to tumor necrosis factor (TNF-α) strongly increased 1) surface expression of intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), and E-selectin, 2) platelet-activating factor (PAF) synthesis as assessed by thrombin challenge, and 3) rate of rolling and adhesion of monocytes. Preincubation of HUVEC with EPA or DHA markedly suppressed PAF synthesis, monocyte rolling, and adherence, whereas expression of endothelial adhesion molecules was unchanged. Also, PAF receptor antagonists markedly suppressed the adhesion rate of monocytes, and EPA or DHA revealed no additional inhibitory capacity. In contrast, arachidonic acid partially reversed the effect of the antagonist. We conclude that ω-3 fatty acids suppress rolling and adherence of monocytes on activated endothelial cells in vitro by affecting endothelial PAF generation.
16
Gaboury, JP y P. Kubes. "Reductions in physiologic shear rates lead to CD11/CD18-dependent, selectin-independent leukocyte rolling in vivo". Blood 83, n.º 2 (15 de enero de 1994): 345–50. http://dx.doi.org/10.1182/blood.v83.2.345.345.
Texto completoResumen
Abstract In this study, we tested the hypothesis that reducing shear rates in postcapillary venules causes CD18-dependent, selectin-independent leukocyte rolling. Intravital microscopy was used to assess shear rate- dependent leukocyte rolling in 25- to 40-microns rat mesenteric venules. Pretreatment of animals with 25 mg/kg fucoidin, a carbohydrate moiety that binds to and inhibits selectin function, essentially abolished the number of spontaneously rolling leukocytes. When shear rates were reduced by 50% (from 438 +/- 36 s-1 to 222 +/- 19 s-1) in the presence of fucoidin, leukocyte rolling increased fourfold, suggesting a selectin-independent mechanism of leukocyte rolling. Administration of CL26, an anti-CD18 antibody, prevented the leukocyte rolling associated with reduced shear rates. A second objective was to determine if the integrin-mediated leukocyte rolling at reduced shear rates would lead to firm adhesion of leukocytes in the presence of a chemotactic stimulus. Animals were pretreated with fucoidin and 100 nmol/L platelet-activating factor (PAF) was superfused over the mesentery. Fucoidin prevented leukocyte rolling and subsequent PAF- induced adhesion at normal shear rates; however, when shear rates were reduced by 50%, a significant CD18-dependent increase in leukocyte rolling (10-fold) and adhesion (5-fold) was noted within 15 minutes. These data raise the possibility that, at lower shear rates, as is the case in various inflammatory conditions, selectin-independent, CD18- dependent leukocyte rolling and subsequent adhesion can occur in postcapillary venules.
17
Gaboury, JP y P. Kubes. "Reductions in physiologic shear rates lead to CD11/CD18-dependent, selectin-independent leukocyte rolling in vivo". Blood 83, n.º 2 (15 de enero de 1994): 345–50. http://dx.doi.org/10.1182/blood.v83.2.345.bloodjournal832345.
Texto completoResumen
In this study, we tested the hypothesis that reducing shear rates in postcapillary venules causes CD18-dependent, selectin-independent leukocyte rolling. Intravital microscopy was used to assess shear rate- dependent leukocyte rolling in 25- to 40-microns rat mesenteric venules. Pretreatment of animals with 25 mg/kg fucoidin, a carbohydrate moiety that binds to and inhibits selectin function, essentially abolished the number of spontaneously rolling leukocytes. When shear rates were reduced by 50% (from 438 +/- 36 s-1 to 222 +/- 19 s-1) in the presence of fucoidin, leukocyte rolling increased fourfold, suggesting a selectin-independent mechanism of leukocyte rolling. Administration of CL26, an anti-CD18 antibody, prevented the leukocyte rolling associated with reduced shear rates. A second objective was to determine if the integrin-mediated leukocyte rolling at reduced shear rates would lead to firm adhesion of leukocytes in the presence of a chemotactic stimulus. Animals were pretreated with fucoidin and 100 nmol/L platelet-activating factor (PAF) was superfused over the mesentery. Fucoidin prevented leukocyte rolling and subsequent PAF- induced adhesion at normal shear rates; however, when shear rates were reduced by 50%, a significant CD18-dependent increase in leukocyte rolling (10-fold) and adhesion (5-fold) was noted within 15 minutes. These data raise the possibility that, at lower shear rates, as is the case in various inflammatory conditions, selectin-independent, CD18- dependent leukocyte rolling and subsequent adhesion can occur in postcapillary venules.
18
Petrousek, Patrik, Tibor Kvackaj, Róbert Kocisko, Jana Bidulska, Miloslav Luptak, Diego Manfredi, Marco Actis Grande y Róbert Bidulsky. "INFLUENCE OF CRYOROLLING ON PROPERTIES OF L-PBF 316L STAINLESS STEEL TESTED AT 298K AND 77K". Acta Metallurgica Slovaca 25, n.º 4 (18 de diciembre de 2019): 283. http://dx.doi.org/10.12776/ams.v25i4.1366.
Texto completoResumen
<p class="AMSmaintext">The goal of the present work is to evaluate mechanical properties and to analyse the microstructure of 316L stainless steel produced by Laser Powder Bed Fusion (L-PBF) follow by rolling with different thickness reduction under ambient and cryogenic conditions. The samples before rolling were heat treated. The static tensile test was realized at ambient and cryogenic (77K) conditions. The L-PBF powder metal production technology approved that is a key technology in the AM area, especially for metal powder materials. Mechanical properties tested at 298K and 77K shows that the application of various thermo-deformation rolling conditions increases of strength properties. Achieved mechanical properties are comparable to conventional bulk materials. The strength properties after the rolling under ambient and cryogenic conditions were significantly increased.<strong></strong></p>
19
Badics, Joe. "The Rolling Stone Archive". Charleston Advisor 25, n.º 1 (1 de julio de 2023): 33–35. http://dx.doi.org/10.5260/chara.25.1.05.
Texto completoResumen
From the first issue in 1967 to the most recent, the Rolling Stone Archive provides access to every article in every issue in PDF format. From its initial focus on popular and specifically rock music, it has expanded its coverage to Americana and popular culture over the years. Indexing is provided to all content, including the shortest news items, covers, and advertisements.
20
Rainger, G. E., A. C. Fisher y G. B. Nash. "Endothelial-borne platelet-activating factor and interleukin-8 rapidly immobilize rolling neutrophils". American Journal of Physiology-Heart and Circulatory Physiology 272, n.º 1 (1 de enero de 1997): H114—H122. http://dx.doi.org/10.1152/ajpheart.1997.272.1.h114.
Texto completoResumen
The kinetics of the response of integrins to activating signal(s) must be rapid to ensure that rolling neutrophils are localized at the sites of inflammation. From video records, we analyzed the adhesion of individual neutrophils in a flow-based in vitro model of endothelial hypoxia and reoxygenation. There were numerous rolling interactions between flowing neutrophils and P-selectin on human umbilical vein endothelial cells after hypoxia, but 90% lasted for < 1 s, with approximately 30% converted to stationary attachment via beta 2-integrin(s). Interleukin-8 (IL-8) and platelet-activating factor (PAF) were responsible for neutrophil activation in this model [G. E Rainger, A. Fisher, C. Shearman, and G. B. Nash. Am. J. Physiol. 269 (Heart Circ. Physiol. 38): H1398-H1406, 1995]. In the presence of a PAF-receptor antagonist, IL-8 acting alone induced conversion of rolling to stationary adhesion in as little as 80 ms after the initial attachment of a neutrophil, with a median response time of 240 ms. In the presence of a monoclonal antibody that neutralized IL-8 activity, PAF acting alone required a minimum duration of rolling of 560 ms to promote stationary adhesion, with a significantly longer median duration of 720 ms. In a reconstituted model, treatment of endothelial cells with hydrogen peroxide induced short-lived rolling of neutrophils supported by P-selectin. Exogenously added IL-8 and/or PAF bound to the endothelial surface and successfully induced the immobilization of neutrophils. Rapid and distinct kinetics of the conversion to stationary adhesion were observed again for IL-8 or PAF. Thus although endothelial-presented signals differed in their rate of action, neutrophils could be localized within one or two endothelial cell diameters of their initial adhesive contact point.
21
De Ceunynck, Karen E. P., Christian G. Peters, Sharjeel A. Chaudhry, Abhishek Jain, Sarah J. Higgins, Omozuanvbo Aisiku, Jennifer Fitch-Tewfik et al. "A Chemical APC Mimetic Protects Endothelium from Thromboinflammatory Injury". Blood 128, n.º 22 (2 de diciembre de 2016): 3835. http://dx.doi.org/10.1182/blood.v128.22.3835.3835.
Texto completoResumen
Abstract Stimulation of protease-activated receptor 1 (PAR1) on endothelium by activated protein C (APC) is protective in animal models of inflammation and APC has been used clinically in sepsis and wound healing. Clinical use of APC in sepsis, however, was terminated as it was compromised by APC's anticoagulant activity, which is associated with bleeding and limits its dosing in patients. We used a small molecule approach to circumvent this problem. With support from the Molecular Libraries Program, we screened 302,457 compounds to identify small molecules that modulated PAR1-mediated platelet activation. One class of PAR1-targeted compounds, which we termed parmodulins, was found to act at the cytosolic face of PAR1, at the G-protein binding sites. When evaluated in endothelial cell cultures,parmodulin 1 (PM1) and parmodulin 2 (PM2) inhibited apoptosis induced by thrombin, TNF-α, or staurosporine, in a manner similar to APC. PAR1 knockdown using siRNA abolished these protective effects demonstrating that parmodulins elicit a cytoprotective pathway by acting through PAR1. To assess the mechanism of action of parmodulin cytoprotection, we first evaluated proximal signaling mechanisms. Parmodulins stimulated phosphorylation of PI3-kinase and Akt in endothelium. Inhibition of Gβγ blocked parmodulin-induced phosphorylation of Akt, indicating that parmodulins act at the cytosolic face of PAR1 by releasing Gβγ. Transcriptional profiling of over 30,000 genes and specific evaluation of NF-kB transcriptional activation showed that exposure to PM2 blocked TNF-α-induced transcriptional activation. In addition to interfering with inflammatory signaling, parmodulins also stimulated the upregulation of cytoprotective proteins such as stanniocalcin-1. Since our premise was that parmodulins could achieve cytoprotective effects without anticoagulant effects, we compared dose curves of APC versus PM2 in both apoptosis assays and standard clotting assays. APC prolonged the aPTT at concentrations lower than those required to achieve cytoprotection of the endothelium. The low APC concentration used in our study was similar to plasma concentrations measured in clinical studies. Hence, these data were consistent with the fact that clinical bleeding was observed at doses of APC used for sepsis. In contrast, despite inhibiting apoptosis as effectively as APC, PM2 had no effect on plasma aPTT at any concentration. Nonetheless, PM2 was able to inhibit LPS- and TNF-α-induced thrombin generation and FXa activation on endothelium owing to its cytoprotective effect. PM2 also prevented TNF-α-induced accumulation of platelets on endothelium in bioengineered microvessels. These data demonstrate that PM2 can reduce inflammation-induced endothelial pro-thrombotic phenotype even without directly inhibiting coagulation factors. To assess the endothelial protective effects of PM2 in vivo we evaluated leukocyte rolling in cremaster venules of mice. Infusion of PM2 significantly reduced surgery-induced leukocyte rolling flux compared to vehicle-treated mice. As selectins are critically involved in leukocyte rolling we monitored soluble E-selectin levels in LPS-induced inflammation. Treatment of mice with PM2 significantly reduced the LPS-induced release of soluble E-selectin. Previously, we demonstrated that PM2 blocks platelet accumulation in a mouse laser injury model of thrombus formation. We here show that infusion of PM2 also significantly reduces fibrin accumulation to 25% of control (p<0.001) at the site of laser injury. Together our data show that PM2 exerts endothelial-mediated anti-inflammatory, anti-coagulant and anti-thrombotic effects in vitro and in vivo. These results demonstrate that modulating PAR1 at the cytosolic face could represent an alternative approach to APC in the treatment of thromboinflammatory disorders like sepsis. Disclosures No relevant conflicts of interest to declare.
22
Zareie, Mohammad, Anton A. van Lambalgen, Piet M. Ter Wee, Liesbeth H. P. Hekking, Eelco D. Keuning, Inge L. Schadee–Eestermans, Dirk Faict et al. "Better Preservation of the Peritoneum in Rats Exposed to Amino Acid-Based Peritoneal Dialysis Fluid". Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 25, n.º 1 (enero de 2005): 58–67. http://dx.doi.org/10.1177/089686080502500112.
Texto completoResumen
Background Glucose-containing peritoneal dialysis fluids (PDF) show impaired biocompatibility, which is related partly to their high glucose content, presence of glucose degradation products, low pH, and lactate buffer, or a combination of these factors. In a rat chronic peritoneal exposure model, we compared effects of an amino acid-based PDF (AA-PDF) with a glucose-containing PDF on the peritoneal microcirculation and morphology. Method Two groups of rats received 10 mL of either fluid daily for 5 weeks via peritoneal catheters connected to implanted subcutaneous mini vascular access ports. Leukocyte–endothelium interactions in the mesenteric venules were investigated by intravital microscopy. Quantification of angiogenesis and fibrosis and inspection of the mesothelial cell layer were performed by light and electron microscopy. Results Daily exposure to glucose-containing PDF resulted in a significant increase in the number of rolling leukocytes in mesenteric venules, whereas instillation of AA-PDF did not change the level of leukocyte rolling. Glucose-containing PDF evoked a significantly higher number of milky spots in the omentum, whereas this response was significantly reduced in animals exposed to the AA-PDF ( p < 0.02). Chronic instillation of glucose-containing PDF induced angiogenesis in various peritoneal tissues, accompanied by fibrosis in the mesentery and parietal peritoneum. Quantitative morphometric evaluation of omentum and mesentery showed a clear trend toward less angiogenesis after treatment with the AA-PDF compared to the glucose-containing PDF, which reached statistical significance in the parietal peritoneum ( p < 0.04). Instillation of AA-PDF resulted in approximately 50% reduction of fibrosis in the mesentery ( p < 0.04) and approximately 25% reduction in the parietal peritoneum ( p < 0.009) compared to glucose-containing PDF. Glucose-containing PDF damaged the mesothelial cell layer, whereas the mesothelium was intact after AA-PDF treatment, as evidenced by electron microscopy. Conclusion Our data in a rat chronic peritoneal exposure model clearly demonstrate reduced immune activation (evidenced by decreased number of rolling leukocytes and decreased induction of omental milky spots) and reduced neoangiogenesis, fibrosis, and mesothelial damage of the peritoneal membrane after treatment with AA-PDF compared to glucose-containing PDF.
23
Fry, Carol J. "Left-Handedness and Tongue-Rolling Ability". Perceptual and Motor Skills 67, n.º 1 (agosto de 1988): 168–70. http://dx.doi.org/10.2466/pms.1988.67.1.168.
Texto completoResumen
948 undergraduates at The Ohio State University were administered the 10-item Edinburgh Handedness Inventory and asked to indicate the extent to which they could turn up the sides of their tongues. Significantly fewer left-handers than right-handers (62.8% and 74.8%, respectively) reported being able to turn up either or both sides. Sex differences in tongue-rolling ability were also noted. Among the 403 men included in the final sample, 77.4% could roll their tongues, whereas only 69 7% of the 491 women could do so.
24
Gaboury, J. P., B. Johnston, X. F. Niu y P. Kubes. "Mechanisms underlying acute mast cell-induced leukocyte rolling and adhesion in vivo." Journal of Immunology 154, n.º 2 (15 de enero de 1995): 804–13. http://dx.doi.org/10.4049/jimmunol.154.2.804.
Texto completoResumen
Abstract It has been proposed that a primary detector mechanism for tissue infection or injury may be the mast cell that releases agents that recruit leukocytes to the appropriate site at risk. The objective of this study was to evaluate the early mechanisms involved in mast cell-induced leukocyte recruitment. We used intravital microscopy to visualize leukocyte-rolling flux and adhesion in single 25 to 40 microns venules in mesenteric preparations that were treated with the mast cell-degranulating agent, compound 48/80 (CMP 48/80). Superfusion of the rat mesentery with CMP 48/80 caused a dose-dependent rise in the number of rolling and adherent cells, events significantly reduced by: 1) mast cell stabilizers, ketotifen, or cromolyn, and 2) chronic treatment with CMP 48/80 to deplete mast cell constituents. The increase in leukocyte flux associated with CMP 48/80 was blocked by diphenhydramine (H1-receptor antagonist) and an anti-P-selectin Ab (PB1.3), but not by the 5-lipoxygenase inhibitor, MK 886. The reduction in the flux of rolling leukocytes translated into fewer adherent leukocytes with diphenhydramine or PB1.3. The CMP 48/80-induced rise in leukocyte adhesion, but not leukocyte flux, was reduced by the platelet-activating factor (PAF)-receptor antagonist (WEB 2086) and an anti-CD18 Ab (CL26). MK 886 did not prevent the increased leukocyte adhesion. In vitro data revealed that mast cell-derived PAF induced essentially all of the leukocyte adhesion to endothelium or protein-coated plastic. These data suggest that mast cell degranulation induces P-selectin-dependent leukocyte rolling and CD18-dependent leukocyte adhesion via histamine and PAF, respectively.
25
Ma, Fang, Liwei Zhan, Chengwei Li, Zhenghui Li y Tingjian Wang. "Self-Adaptive Fault Feature Extraction of Rolling Bearings Based on Enhancing Mode Characteristic of Complete Ensemble Empirical Mode Decomposition with Adaptive Noise". Symmetry 11, n.º 4 (10 de abril de 2019): 513. http://dx.doi.org/10.3390/sym11040513.
Texto completoResumen
Originally, a rolling bearing, as a key part in rotating machinery, is a cyclic symmetric structure. When a fault occurs, it disrupts the symmetry and influences the normal operation of the rolling bearing. To accurately identify faults of rolling bearing, a novel method is proposed, which is based enhancing the mode characteristics of complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN). It includes two parts: the first is the enhancing decomposition of CEEMDAN algorithm, and the second is the identified method of intrinsic information mode (IIM) of vibration signal. For the first part, the new mode functions (CIMFs) are obtained by combing the adjacent intrinsic mode functions (IMFs) and performing the corresponding Fast Fourier Transform (FFT) to strengthen difference feature among IMFs. Then, probability density function (PDF) is used to estimate FFT of each CIMF to obtain overall information of frequency component. Finally, the final intrinsic mode functions (FIMFs) are obtained by proposing identified method of adjacent PDF based on geometrical similarity (modified Hausdorff distance (MHD)). FIMFs indicate the minimum amount of mode information with physical meanings and avoid interference of spurious mode in original CEEMDAN decomposing. Subsequently, comprehensive evaluate index (Kurtosis and de-trended fluctuation analysis (DFA)) is proposed to identify IIM in FIMFs. Experiment results indicate that the proposed method demonstrates superior performance and can accurately extract characteristic frequencies of rolling bearing.
26
Kurtel, H., L. Liao, M. B. Grisham, P. Tso, T. Y. Aw, D. C. Anderson, M. Miyasaka y D. N. Granger. "Mechanisms of oxidized chylomicron-induced leukocyte-endothelial cell adhesion". American Journal of Physiology-Heart and Circulatory Physiology 268, n.º 6 (1 de junio de 1995): H2175—H2182. http://dx.doi.org/10.1152/ajpheart.1995.268.6.h2175.
Texto completoResumen
The objectives of this study were to determine whether oxidatively modified chylomicrons (oxCM) can elicit leukocyte-endothelial cell adhesion in the mesenteric microcirculation and to define the mechanisms underlying the oxCM-induced adhesive interactions. Oxidation of chylomicrons (CM) with the peroxyl radical generator 2,2'-azobis(2-amidinopropane)hydrochloride was associated with the formation of thiobarbituric acid-reactive substances and lipid hydroperoxides. Leukocyte rolling, adherence, and emigration as well as erythrocyte velocity were monitored in rat mesenteric venules infused with either native CM or oxCM. oxCM, but not native CM, increased the numbers of rolling, adherent, and emigrated leukocytes. The oxCM-induced leukocyte adherence was significantly blunted by pretreating the animals with either superoxide dismutase, a platelet-activating factor (PAF) receptor antagonist, or monoclonal antibodies (MAb) directed against either CD11/CD18 or intracellular adhesion molecule 1. A MAb against P-selectin reduced oxCM-induced leukocyte rolling but not adherence. These findings suggest that the increased plasma oxCM levels associated with ingestion of oxidized lipids may promote leukocyte adhesion through a mechanism that involves the superoxide anion, PAF, and adhesion receptors on leukocytes and endothelial cells.
27
Gaboury, J., R. C. Woodman, D. N. Granger, P. Reinhardt y P. Kubes. "Nitric oxide prevents leukocyte adherence: role of superoxide". American Journal of Physiology-Heart and Circulatory Physiology 265, n.º 3 (1 de septiembre de 1993): H862—H867. http://dx.doi.org/10.1152/ajpheart.1993.265.3.h862.
Texto completoResumen
The objective of this study was to determine whether the antiadhesive effects of NO for leukocytes are related to its ability to scavenge superoxide in vivo. Intravital microscopy was used to monitor leukocyte adherence and flux as well as velocity and number of rolling leukocytes in 25- to 40-microns venules. The superoxide-generating system, hypoxanthine and xanthine oxidase (HX-XO), was infused into the mesenteric circulation in untreated animals and in animals pretreated with either superoxide dismutase (SOD) or the NO donor, SIN 1. In another series of studies, the mesenteric preparation was superfused with either platelet-activating factor (PAF) or leukotriene B4 (LTB4) followed by the administration of either SIN 1 or SOD. HX-XO infusion caused a significant increase in the number of rolling and adherent leukocytes (responses that were entirely inhibited by SOD or SIN 1). SOD and SIN 1 both attenuated the PAF-induced but not the LTB4-induced leukocyte adherence. The observation that both SOD and SIN 1 inhibit leukocyte adhesion only under conditions associated with superoxide formation (HX-XO and PAF, but not LTB4) strongly suggests that the antiadhesion properties of NO are related to its ability to inactivate the superoxide anion.
28
Nourshargh, S., SW Larkin, A. Das y TJ Williams. "Interleukin-1-induced leukocyte extravasation across rat mesenteric microvessels is mediated by platelet-activating factor". Blood 85, n.º 9 (1 de mayo de 1995): 2553–58. http://dx.doi.org/10.1182/blood.v85.9.2553.bloodjournal8592553.
Texto completoResumen
Although our understanding of the molecular interactions that mediate the adhesion of leukocytes to venular endothelial cells has greatly expanded, very little is known about the mechanisms that mediate the passage of leukocytes across the vessel wall in vivo. The aim of the present study was to investigate the role of endogenously formed platelet-activating factor (PAF) in the process of leukocyte extravasation induced by interleukin-1 (IL-1). To determine at which stage of emigration PAF was involved, we studied the behavior of leukocytes within rat mesenteric microvessels by intravital microscopy. Rats were injected intraperitoneally with saline, recombinant rat IL-1 beta (IL-1 beta), or the peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) 4 hours before the exteriorization of the mesenteric tissue. In animals treated with IL-1 beta there was a significant increase in the number of rolling and adherent leukocytes within venules (20- to 40-micron diameter) and in the number of extravasated leukocytes in the tissue. Pretreatment of rats with the PAF receptor antagonist UK-74,505 had no effect on the leukocyte responses of rolling and adhesion, but significantly inhibited the migration of the leukocytes across the vessel wall induced by IL-1 beta (76% inhibition). A structurally unrelated PAF antagonist, WEB-2170, produced the same effect (64% inhibition). However, in contrast, UK-74,505 had no effect on the leukocyte extravasation induced by FMLP, indicating selectivity for the response elicited by certain mediators. These results provide the first line of direct evidence for the involvement of endogenously formed PAF in the process of leukocyte extravasation induced by IL-1 in vivo.
29
Ostrovsky, Lena, Alison J. King, Samantha Bond, Debra Mitchell, Diane E. Lorant, Guy A. Zimmerman, Robert Larsen, Xiao Fe Niu y Paul Kubes. "A Juxtacrine Mechanism for Neutrophil Adhesion on Platelets Involves Platelet-Activating Factor and a Selectin-Dependent Activation Process". Blood 91, n.º 8 (15 de abril de 1998): 3028–36. http://dx.doi.org/10.1182/blood.v91.8.3028.3028_3028_3036.
Texto completoResumen
The aim of this study was to identify the molecular mechanisms involved in neutrophil adhesion to immobilized platelets with particular focus on the possible existence of a juxtacrine system for neutrophil-platelet interactions. Platelets were immobilized onto collagen (type I)-coated coverslips that were placed in a flow chamber and neutrophils were perfused across these confluent monolayers at a shear stress of 1 to 4 dynes/cm2. Neutrophils rolled, and a significant proportion (25% to 50%) adhered to platelet monolayers. P-selectin was expressed in very large quantities on the surface of platelets and mediated all of the rolling, whereas the β2-integrin mediated firm adhesion. An activation mechanism for adhesion was necessary inasmuch as fixed neutrophils continued to roll on immobilized platelets, but did not adhere. Platelets adherent to collagen produced significant levels of platelet-activating factor (PAF). Accordingly, the firm adhesion of neutrophils to platelets was significantly inhibited by a PAF receptor antagonist (WEB 2086). Treatment of only the platelets with acetylhydrolase, which converts membrane-associated PAF to lyso-PAF, prevented 60% of the adhesion. These data suggest that PAF, on the surface of platelets, mediated a significant portion of the adhesive interaction. Addition of some selectin-binding carbohydrates (fucoidan or soluble SLEx analogs but not dextran sulfate) to the platelets caused rolling neutrophils to immediately adhere, an event that was not observed on histamine or thrombin-treated endothelium or P-selectin transfectants. These data support the view that a juxtacrine activation process exists on immobilized platelets for neutrophils. This process can be greatly enhanced on platelets and may involve a signaling mechanism through P-selectin.
30
Trinkaus, John. "Stop Sign Compliance: A Final Look". Perceptual and Motor Skills 85, n.º 1 (agosto de 1997): 217–18. http://dx.doi.org/10.2466/pms.1997.85.1.217.
Texto completoResumen
A concluding study to a number of informal enquiries conducted over the years, on drivers' compliance with stop signs in a residential community, suggests that this traffic control device is now largely ignored by motorists. During a 17-yr. period full stops declined from about 37% to 1% and rolling stops from approximately 34% to 2%.
31
Xiong, Qing, Weihua Zhang, Tianwei Lu, Guiming Mei y Shulin Liang. "A Fault Diagnosis Method for Rolling Bearings Based on Feature Fusion of Multifractal Detrended Fluctuation Analysis and Alpha Stable Distribution". Shock and Vibration 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/1232893.
Texto completoResumen
When rolling bearings fail, it is usually difficult to determine the degree of damage. To address this problem, a new fault diagnosis method was developed to perform feature extraction and intelligent classification of various fault position and damage degree of rolling bearing signals. Firstly, Multifractal Detrended Fluctuation Analysis (MFDFA) was used to compute five MFDFA features while five Alpha Stable Distribution (ASD) features were obtained by fitting the distribution to the vibration signals of each status and calculating the Probability Density Function (PDF). Secondly, Kernel Principle Component Analysis (KPCA) was used to achieve dimensionality reduction fusion of the combination of original features to gain the Kernel Principle Component Fusion Features (KPCFFs). Thirdly, the KPCFFs served as the input of Least Squares Support Vectors Machine (LSSVM) based on Particle Swarm Optimization (PSO) to assess rolling bearings’ fault position and damage severity. Finally, the effectiveness of the method was validated by bench test data. The results demonstrated that the developed method can achieve intelligent diagnosis of rolling bearings’ fault position and damage degree and can yield better diagnosis accuracy than single feature method or corresponding single feature fusion method.
32
Article, Editorial. "ENGINEERING CENTRE OF RUSSIAN RAILWAYS AND SIEMENS REMOTE ANALYSIS OF TECHNICAL CONDITION OF LASTOCHKA TRAINS". World of Transport and Transportation 15, n.º 1 (28 de febrero de 2017): 63. http://dx.doi.org/10.30932/1992-3252-2017-15-1-30.
Texto completoResumen
[For the English full text of the article please see the attached PDF-File (English version follows Russian version)].Russian Railways Russian Railways and Siemens have launched a unique processing and analysis centre to handle data received from the operation of rolling stock and railway infrastructure. Based on releases of press service of JSC.
33
Pisarenko, V. V. "INTERACTION OF A WHEEL WITH A RAIL DURING ROLLING". World of Transport and Transportation 16, n.º 1 (28 de febrero de 2018): 26–32. http://dx.doi.org/10.30932/1992-3252-2018-16-1-3.
Texto completoResumen
[For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version)].ABSTRACT The problem of uneven wear of a wheel set is considered by many scientists of the world, in the works related to car building. New software complexes for mathematical modeling are being created, and each follows its own theory of rolling stock dynamics. In this article the main provisions for deformation and wear of a wheel along the circle of rolling during car movement are considered. In this case, the elastic sliding model is described in more detail. During wheel rolling and in the presence of torque in the contact area, there is always a gripping area that is located at the entrance, and an area of slippage at the exit. It is proved that the coefficient of slippage is equal to deformation in the gripping area. Under certain kinematic and dynamic conditions, a stress distribution graph is plotted in the contact zone. On the basis of the theory of tangential stresses, a displacement formula is obtained, which is transformed into a new formula for the creep coefficient, which retains the physical meaning of the value found. Keywords: theory of rolling stock dynamics, wheel set, rail, creep coefficient, sliding, gripping, contact spot, wheel rolling, stress distribution.
34
Trinkaus, John. "Stop Sign Compliance: A Follow-up Look". Perceptual and Motor Skills 76, n.º 3_suppl (junio de 1993): 1218. http://dx.doi.org/10.2466/pms.1993.76.3c.1218.
Texto completoResumen
Analysis of 324 observations at a previously studied intersection showed a continuing decrease in full stops ( n = 13) with increased rolling ( n = 19) and no stops ( n = 292), suggesting change in meaning of beliefs.
35
Li, François-Xavier y Michel Laurent. "Occlusion Rate of Ball Texture as a Source of Velocity Information". Perceptual and Motor Skills 81, n.º 3 (diciembre de 1995): 871–80. http://dx.doi.org/10.2466/pms.1995.81.3.871.
Texto completoResumen
When a ball is rolling on the ground toward an observer, its elements of texture are successively occluded. The number of the elements of texture occluded per unit of time determines the occlusion rate. The aim of this study was to examine the role of the occlusion rate of ball texture and the velocity of the ball in the perception of the time remaining before the arrival. If the occlusion rate is used to perceive the time to arrival, then timing the initiation of movement should depend on occlusion rate. On the other hand, if the optical variable tau is exclusively used, then no variation is expected. 20 subjects were required to avoid balls rolling directly toward them. Three different ball textures and five ball velocities were used, leading to 10 different occlusion rates. The results showed that the timing of the initiation of the movement was not modified by variations of occlusion rate. However, the velocity of the avoidance movement increased with occlusion rate. The role of timing initiation and movement velocity in the control of the action are discussed, and it is suggested that occlusion rate is perceived and taken into account in the control of avoidance movements.
36
Asako, H., R. E. Wolf, D. N. Granger y R. J. Korthuis. "Phalloidin prevents leukocyte emigration induced by proinflammatory stimuli in rat mesentery". American Journal of Physiology-Heart and Circulatory Physiology 263, n.º 6 (1 de diciembre de 1992): H1637—H1642. http://dx.doi.org/10.1152/ajpheart.1992.263.6.h1637.
Texto completoResumen
The objective of this study was to determine whether phalloidin, a potent microfilament stabilizer, can modify inflammatory mediator-induced leukocyte adhesion and extravasation in postcapillary venules of the rat mesentery. To address this issue, the rat mesentery was prepared for in vivo microscopic observation. Venules with initial diameters ranging between 25 and 35 microns were selected for study. Erythrocyte velocity, vessel diameter, leukocyte rolling velocity, and the number of adherent (stationary for 30 s) and emigrated leukocytes were initially determined during superfusion of the mesentery with phosphate-buffered saline. After these variables were recorded during the control period, either 100 nM platelet-activating factor (PAF), 20 nM leukotriene B4 (LTB4), or 1 microM N-formyl-methionyl-leucyl-phenylalanine (FMLP) was added to the superfusate. Repeat measurements were obtained between 50 and 60 min after initial exposure to the inflammatory mediator. In some experiments, rats were given phalloidin (25 or 500 micrograms/kg iv) 30 min before superfusion with the inflammatory mediators. Superfusion of the mesentery with either PAF, LTB4, or FMLP enhanced leukocyte adherence and emigration and reduced leukocyte rolling velocity. Pretreatment with the low dose of phalloidin effectively prevented leukocyte emigration but had no effect on the increased leukocyte adherence elicited by the three inflammatory mediators. However, when administered at the higher dose, phalloidin prevented both leukocyte adherence and emigration. Neither dose of phalloidin altered the upregulation of neutrophil membrane CD11/CD18 glycoprotein adherence complex induced by PAF or LTB4. These results are consistent with the concept that PAF, LTB4, and FMLP increase leukocyte extravasation by a process that may involve alterations in the endothelial cell cytoskeleton.
37
TATARKANOV, Aslan Adal bievich, Islam Alexandrovich ALEXANDROV y Andrej Vladimirovich OLEJNIK. "EVALUATION OF THE CONTACT SURFACE PARAMETERS AT KNURLING FINNED HEAT-EXCHANGING SURFACE BY KNURLS AT RING BLANKS". Periódico Tchê Química 17, n.º 36 (20 de diciembre de 2020): 372–89. http://dx.doi.org/10.52571/ptq.v17.n36.2020.387_periodico36_pgs_372_389.pdf.
Texto completoResumen
Tubular parts with an external finned heat-exchanging surface are usually produced by the laborious method of cutting on lathes. Besides, there is a method for the high-performance manufacturing of fins by cold knurling with ring-cut knurls, which, compared with cutting, reduces labor intensity by two to six times with a significant increase in the operational properties of the product. The disadvantage of the cold knurling method with ring-cut knurls can be unwanted surface defects and deformations of the entire product. Obtaining finned surfaces on ring blanks with high surface quality during knurling requires accurate calculation of the ratio of longitudinal and transverse strains. The most important factors determining the ratio of longitudinal and transverse strains (rolling-out and rolling-off) are the length and width of the contact surface. The need for a quantitative assessment of the parameters of longitudinal and transverse strains determined the purpose of this manuscript. This study aimed to develop a methodology for calculating the contact surface of a knurl with a ring blank (pipe) when knurling with ring-cut knurls. The proposed method for calculating the knurl's contact surface with a tube when knurling with ring-cut knurls allows for estimating the recommended range of pipe sizes for knurling. Based on the dependencies mentioned in the manuscript, the limiting sizes for blank pipes were calculated to ensure high-quality finning. Experiments on cold rolling of ribbing on pipes with different lengths and diameter ratios were carried out, confirming the possibility of using the proposed methodology for calculating the knurl's contact surface with a pipe when knurling heat-exchanging finning with ring-cut knurls.
38
Dimitrov, R. "ON THE IMPACT OF THE CHARACTERISTICS OF ROLLING STOCK ON SHUNTING RESISTANCE OF RAIL CIRCUITS". World of Transport and Transportation 16, n.º 5 (28 de octubre de 2018): 50–69. http://dx.doi.org/10.30932/1992-3252-2018-16-5-5.
Texto completoResumen
For the English full text of the article please see the attached PDF-File (English version follows Russian version).ABSTRACT The effect of a combination of rolling stock characteristics, including wheel set electrical resistance, axle/wheel load, vehicle speed, electrical resistance of «wheel-rail» contact, has been studied. The data of three reference vehicles - a biaxial rail car, a four-axle conventional and a four-axle high-speed locomotive were studied. Two approaches are used which are deterministic and probabilistic ones (Monte Carlo method). On their basis, the process of detecting static and dynamic shunts for three ranges of speeds of movement and two degrees of rail pollution with an insulating film is provided. Keywords: railway, rail circuit, track circuit, electrical resistance, static shunt, dynamic shunt, rolling stock.
39
Tarasov, D. E. "THE DEVELOPMENTS OF HYBRID ROAD-RAIL ROLLING STOCK IN RUSSIA". World of Transport and Transportation 15, n.º 2 (28 de abril de 2017): 74–80. http://dx.doi.org/10.30932/1992-3252-2017-15-2-7.
Texto completoResumen
[For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version)].ABSTRACT The article deals with the aspects of the development of hybrid road-rail rolling stock - automotive tractors of various purposes equipped with devices for movement along the railway track. Information is provided on the design features, single and serial models of machines built by the plants of the USSR and modern domestic enterprises. Depending on the specificity and type of hybrid road-rail equipment, the author identifies the current problems and directions of development of hybrid road-rail vehicles, the design and production of which are designed to become at least ordered, technological and standardized. Keywords: hybrid road-rail transport, rolling stock, road transport, rail transport, innovations.
40
Zinchenko, Mykhailo, Oleh Potap, Maria Rybalchenko y Ivan Manachyn. "Modernization of laboratory rolling mill 150 for the formation of students 'studies of automation object research". System technologies 3, n.º 134 (5 de abril de 2021): 87–98. http://dx.doi.org/10.34185/1562-9945-3-134-2021-10.
Texto completoResumen
Studying the operation of automated control systems using computers significantly re-duces the time, but does not give a complete picture of the system on a real object. Therefore, the use of real objects for the study of control systems in the educational process is appropriate and useful. The purpose of the study is to modernize the laboratory rolling mill 150, designed for rolling lead, tin and plasticine, and equip it with sensors and actuators. The manual pressure device of the rolling stand was replaced by an automated one, for which an worm gearbox was additionally installed, which allowed to increase the total gear ratio to 94.5. The thrust screws are moved from the AC motor, which is controlled by the DOP-103BQ operator panel and the MS-300 frequency converter with built-in PLC. As a displacement sensor used photopulse sensor PDF-3. The installed equipment and the developed software for the operator panel and the PLC provided high accuracy of in-stallation of pressure screws in the set position. Additionally, software was developed to measure the power parameters of the rolling process: the rolling force and the electrical parameters of the DC motor of the drive of the rolling stand. The software allows you to configure the board, ie select the type of board, the channels used to measure voltage signals, select measurement ranges, signal color on the graph, signal polling frequency, number of points to display on the graph, parameters of graph coordinate axes. In the process of measurement, the output of signals to the monitor screen is performed simultaneously. Before rolling, the measurement process is started using the keyboard or mouse and the change of parameters is displayed on the screen in real time. At the end of the rolling process, the measurement stops, and the graphs of parameter changes over time remain on the monitor screen, which allows you to quickly analyze the process. The measurement results can be saved in an Excel file and then the file can be viewed. The file stores: the time of measurement of parameters and the values of parameters those were measured. Measurement of power parameters and sizes of rolled products before and after rolling allowed to determine the stiffness of the stand and rolled metal, which is necessary to calculate the transmission coefficients of the automated tuning system of the rolling stand.
41
Zhao, Yao, Nan Liu, Yijun Wang y Kathleen T. Hickey. "A rolling-horizon pharmacokinetic pharmacodynamic model for warfarin inpatients in transient clinical states". Personalized Medicine 13, n.º 1 (enero de 2016): 21–32. http://dx.doi.org/10.2217/pme.15.41.
Texto completo
42
Mori, Naoharu, Yoshinori Horie, Mary E. Gerritsen y D. Neil Granger. "Ischemia-reperfusion induced microvascular responses in LDL-receptor −/− mice". American Journal of Physiology-Heart and Circulatory Physiology 276, n.º 5 (1 de mayo de 1999): H1647—H1654. http://dx.doi.org/10.1152/ajpheart.1999.276.5.h1647.
Texto completoResumen
The objective of this study was to determine whether the microvascular responses to ischemia and reperfusion (I/R) are altered in an animal model of atherosclerosis, the low-density lipoprotein-receptor knockout (LDLr −/−) mouse. Intravital video microscopy was used to monitor venular wall shear rate, leukocytes rolling velocity, the number of rolling, adherent and emigrated leukocytes, and albumin leakage in cremasteric postcapillary venules of wild-type (B6129) and LDLr −/− mice exposed to 60 min of ischemia and 60 min of reperfusion. The postcapillary venules of LDLr −/− mice exhibited two- to threefold larger increments in the number of adherent leukocytes and a more profound albumin leakage response to I/R than venules in wild-type mice. The exaggerated inflammatory responses noted in LDLr −/− mice placed on a normal diet were not exacerbated by a high-cholesterol diet. Treatment of LDLr −/− mice with either a platelet-activating factor (PAF) receptor antagonist (WEB-2086) or a monoclonal antibody (YN-1) against the endothelial cell adhesion molecule, intercellular adhesion molecule 1 (ICAM-1), markedly attenuated the I/R-induced leukocyte adherence and albumin leakage. These findings indicate that atherogenic mice are more vulnerable to the deleterious microvascular effects of I/R and that PAF-mediated, ICAM-1-dependent leukocyte adhesion contributes to this exaggerated response to I/R.
43
Borisov, Stanislav, Ekaterina Koltunova y Sergei Kladiev. "Traction asynchronous electric drive of mine electric locomotivesimulation model structure improvement". Journal of Mining Institute 247 (16 de marzo de 2021): 1–8. http://dx.doi.org/10.31897/pmi.2021.1.12.
Texto completoResumen
The article discusses the solution to the problem of underground railway transport slipping in dynamic modes, which occurs when there is a significant difference in the speeds of the driving and driven pairs of wheels. The state of the rail surfaces largely determines the coefficient of adhesion, therefore, using a mathematical model, the condition for the dependence of the magnitude of slipping and tractive effort is selected. For effective acceleration and deceleration of an electric locomotive, it is necessary to control the coefficient of adhesion at a certain level. A simulation model of rolling stock has been created, which for the first time takes into account a mechanical system with distributed parameters. In the structural diagram of the automatic control system of traction electric drives with frequency regulation, such factors as the volume of goods being moved, rolling friction, slope (rise) levels and the state of the rail track are taken into account. The simulation results show the features of the movement and stops of the freight train not only by the diagrams of speed and forces in the modes of acceleration-deceleration and uniform movement, but also the positions of the plungers and tractive forces on the couplings of the electric locomotive and all trolleys involved in the movement of goods. The practical application of the proposed method lies in the possibility of starting a heavily laden train from its place on the ascent section in conditions of insufficient adhesion coefficient with contaminated roads.
44
Batista, Nathália Vieira, Roberta Cristelli Fonseca, Denise Perez, Rafaela Vaz Sousa Pereira, Juliana de Lima Alves, Vanessa Pinho, Ana Maria Caetano Faria y Denise Carmona Cara. "Lack of Platelet-Activating Factor Receptor Attenuates Experimental Food Allergy but Not Its Metabolic Alterations regarding Adipokine Levels". BioMed Research International 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/8601359.
Texto completoResumen
Platelet-activating factor (PAF) is known to be an important mediator of anaphylaxis. However, there is a lack of information in the literature about the role of PAF in food allergy. The aim of this work was to elucidate the participation of PAF during food allergy development and the consequent adipose tissue inflammation along with its alterations. Our data demonstrated that, both before oral challenge and after 7 days receiving ovalbumin (OVA) diet, OVA-sensitized mice lacking the PAF receptor (PAFR) showed a decreased level of anti-OVA IgE associated with attenuated allergic markers in comparison to wild type (WT) mice. Moreover, there was less body weight and adipose tissue loss in PAFR-deficient mice. However, some features of inflamed adipose tissue presented by sensitized PAFR-deficient and WT mice after oral challenge were similar, such as a higher rate of rolling leukocytes in this tissue and lower circulating levels of adipokines (resistin and adiponectin) in comparison to nonsensitized mice. Therefore, PAF signaling through PAFR is important for the allergic response to OVA but not for the adipokine alterations caused by this inflammatory process. Our work clarifies some effects of PAF during food allergy along with its role on the metabolic consequences of this inflammatory process.
45
Article, Editorial. "DIGITALISATION OF RAIL TRANSPORTATION". World of Transport and Transportation 15, n.º 2 (28 de abril de 2017): 81. http://dx.doi.org/10.30932/1992-3252-2017-15-2-28.
Texto completoResumen
[For the English full text of the article please see the attached PDF-File (English version follows Russian version)].On 15 March 2017, Russian Railways conducted a meeting with participants in the freight rail transportation market attended by top managers from freight owners, rolling stock operators, the wagon-repair complex and heads of industry associations, as well as representatives from Russia’s Ministry of Transport and Federal Antimonopoly Service. Based on releases of press service of JSC Russian Railways
46
Tran, P. T., P. S. Grigoriev y K. E. Suvorova. "CALCULATED DEPENDENCIES AND ESTIMATES OF FREQUENCIES AND VIBRATION MODES OF SHELLS OF RAIL TANK WAGONS". World of Transport and Transportation 16, n.º 5 (28 de octubre de 2018): 84–90. http://dx.doi.org/10.30932/1992-3252-2018-16-5-7.
Texto completoResumen
For the English full text of the article please see the attached PDF-File (English version follows Russian version).ABSTRACT The article gives the procedure for calculating the frequencies of natural oscillations of a shell of a railway tank wagons, taking into account its incomplete filling with liquid cargo. This task is relevant, since it is related to the conditions of safe operation of rolling stock. In this formulation, the solution of the problem is, of course, not done by the finished tracing paper. Including using the hypotheses of the absence of annular deformations of the shear of the shell of the tanks. The reliability of the calculated results is also confirmed by the experimental data obtained in time when testing eight-axis tanks. Keywords: rolling stock, tank car, rail tank wagon, tank oscillations, semimuscular theory of shells, natural frequencies, underfilling of liquid cargo.
47
Zarechkin, E. Yu. "NEW GUIDELINES OF BUSINESS ACTIVITIES OF THE JSC RUSSIAN RAILWAYS". World of Transport and Transportation 14, n.º 1 (28 de febrero de 2016): 99–109. http://dx.doi.org/10.30932/1992-3252-2016-14-1-33.
Texto completoResumen
[For the English full text of the article please see the attached PDF-File (English version follows Russian version)].The JSC Russian Railways has taken steps since first days of 2016 for attracting new passengers, and cargo shipments, improving available service for forwarding companies, developing ties with partners in joint ventures and foreign contractors, enhancing capacity of infrastructure, traction facilities and rolling stock. (According to news releases by Press service of the JSC Russian Railways, http://press.rzd.ru/news/public/ru http://eng.rzd.ru/newse/public/en)
48
Rosyaria, Arkha y Kholifatul Ummah. "Perbedaan antara Pemijatan Rolling Massage dan Counterpresure Massage pada Ibu Bersalin Kala I Fase Aktif terhadap Penurunan Skala Nyeri pada Persalinan Kala 1 Fase Aktif Di PMB Domingas S.ST, M.Kes Surabaya". Jurnal Kebidanan 12, n.º 2 (11 de octubre de 2022): 130–37. http://dx.doi.org/10.35874/jib.v12i2.1089.
Texto completoResumen
Nyeri persalinan merupakan kondisi fisiologis yang secara umum dialami oleh hampir semua ibu bersalin. Selama persalinan dan kelahiran pervaginam, nyeri disebabkan oleh kontraksi rahim.dilatasi serviks,dan distensi perinium.pada studi pendahuluan di PMB Domingas SST.M.Kes pada 14 ibu bersalin kala 1 fase aktif di dapatkan hasil 13 (92,85%) ibu bersalin merasakan nyeri pada saat persalinan. Penelitian ini bertujuan untuk mengetahui perbedaan antara pemijatan rolling massase dan counterpresure massase pada ibu bersalin kala I fase aktif terhadap penurunan skala nyeri pada persalinan kala I fase aktif. Tempat penelitian di laksanakan di PMB Domingas SST.M.kes. Selama 3-4 minggu. Penelitian menggunakan pendekatan Quesi eksperimental dengan two group desain post-test. Berdasarkan hasil uji chi square diperoleh nilai p value 0,05 jika p value < nilai α 0,05, maka H0 ditolak dan H1 diterima. Hal ini menunjukan adanya pengaruh massage counter pressure terhadap tingkat nyeri ibu bersalin primigravida kala I fase aktif. Hasil : Dari 7 ibu bersalin yang diberikan rolling massage didapatkan 3 ibu bersalin (42,85% dengan nyeri sedang, 3 ibu bersalin (42,85%) dengan nyeri ringan berat dan 1 ibu bersalin (14,2%) dengan nyeri sangat berat. Sedangkan 7 ibu bersalin yang diberikan counterpresure didapatkan 6 ibu bersalin (85,7%) dengan nyeri ringan dan 1 ibu bersalin (14,2%) dengan nyeri sedang. Kesimpulan : Hal ini menunjukan adanya pengaruh pemijatan rolling massage dan counterpressure terhadap tingkat nyeri ibu bersalin kala 1 fase aktif di PMB Domingas SST.M.Kes Surabaya.
49
Christensen, Jesper, Susan F. Cotmore y Peter Tattersall. "Minute Virus of Mice Initiator Protein NS1 and a Host KDWK Family Transcription Factor Must Form a Precise Ternary Complex with Origin DNA for Nicking To Occur". Journal of Virology 75, n.º 15 (1 de agosto de 2001): 7009–17. http://dx.doi.org/10.1128/jvi.75.15.7009-7017.2001.
Texto completoResumen
ABSTRACT Parvoviral rolling hairpin replication generates palindromic genomic concatemers whose junctions are resolved to give unit-length genomes by a process involving DNA replication initiated at origins derived from each viral telomere. The left-end origin of minute virus of mice (MVM), oriL, contains binding sites for the viral initiator nickase, NS1, and parvovirus initiation factor (PIF), a member of the emerging KDWK family of transcription factors. oriL is generated as an active form, oriLTC, and as an inactive form, oriLGAA, which contains a single additional nucleotide inserted between the NS1 and PIF sites. Here we examined the interactions on oriLTC which lead to activation of NS1 by PIF. The two subunits of PIF, p79 and p96, cooperatively bind two ACGT half-sites, which can be flexibly spaced. When coexpressed from recombinant baculoviruses, the PIF subunits preferentially form heterodimers which, in the presence of ATP, show cooperative binding with NS1 on oriL, but this interaction is preferentially enhanced on oriLTC compared to oriLGAA. Without ATP, NS1 is unable to bind stably to its cognate site, but PIF facilitates this interaction, rendering the NS1 binding site, but not the nick site, resistant to DNase I. Varying the spacing of the PIF half-sites shows that the distance between the NS1 binding site and the NS1-proximal half-site is critical for nickase activation, whereas the position of the distal half-site is unimportant. When expressed separately, both PIF subunits form homodimers that bind site specifically to oriL, but only complexes containing p79 activate the NS1 nickase function.
50
Nezevak, V. L. y A. P. Shatokhin. "FEATURES OF THE TRACTION LOAD FOR DETERMINING THE PARAMETERS OF THE ELECTRIC ENERGY STORAGE DEVICE". World of Transport and Transportation 16, n.º 2 (28 de abril de 2018): 84–94. http://dx.doi.org/10.30932/1992-3252-2018-16-2-8.
Texto completoResumen
For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version). The studies were carried out with the support of the Russian Foundation for Basic Research for Project No. 17-20-01148 ofi_m_ RZD/17. ABSTRACT Based on the data regarding operation of locomotives of the series 2ES6 and 2ES10, the averaged parameters of the electric power storage in the DC traction system on lines with heavy and long-distance trains have been identified. The modes of the storage devices are characterized by a shortterm nature. The average duration of their operation in the charging mode is approximately 100 s, and the volume of the returned energy by the electric rolling stock, which determines the energy capacity, averages 100 kW•h, with a maximum power of 7,1 MW. The processing of measurement results shows that the observed distributions of stresses and traction load of the substation are not subject to Gauss’s laws. Keywords: railway, traction power supply system, heavy traffic, traction load, energy efficiency, sectioning post, power storage, electric rolling stock, experiment.