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TEC

About: TEC is a research topic. Over the lifetime, 5119 publications have been published within this topic receiving 84696 citations.


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TL;DR: In this paper, the authors reported the global distribution of the TEC by analyzing more than 750,000 echoes of the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS).
Abstract: The Martian ionosphere's local total electron content (TEC) and the neutral atmosphere scale height can be derived from radar echoes reflected from the surface of the planet We report the global distribution of the TEC by analyzing more than 750,000 echoes of the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) This is the first direct measurement of the TEC of the Martian ionosphere The technique used in this paper is a novel 'transmission-mode' sounding of the ionosphere of Mars in contrast to the Active Ionospheric Sounding experiment (AIS) on MARSIS, which generally operates in the reflection mode This technique yields a global map of the TEC for the Martian ionosphere The radar transmits a wideband chirp signal that travels through the ionosphere before and after being reflected from the surface The received waves are attenuated, delayed and dispersed, depending on the electron density in the column directly below the spacecraft In the process of correcting the radar signal, we are able to estimate the TEC and its global distribution with an unprecedented resolution of about 01 deg in latitude (5 km footprint) The mapping of the relative geographical variations in the estimated nightside TEC data reveals an intricate web of high electron density regions that correspond to regions where crustal magnetic field lines are connected to the solar wind Our data demonstrates that these regions are generally but not exclusively associated with areas that have magnetic field lines perpendicular to the surface of Mars As a result, the global TEC map provides a high-resolution view of where the Martian crustal magnetic field is connected to the solar wind We also provide an estimate of the neutral atmospheric scale height near the ionospheric peak and observe temporal fluctuations in peak electron density related to solar activity

122 citations

Journal ArticleDOI
TL;DR: In this article, a new improved design portable asymmetrical solar still has been designed, fabricated and tested over six typical summer days (between 27/08/2014 and 07/09/2014) under the real climatic conditions of Semnan (35°33′N, 53°23′E), Iran.

121 citations

Journal ArticleDOI
TL;DR: In this article, a method for computing the TEC with a precision of about 2-3 TECU and to detect Travelling Ionospheric Disturbances using GPS measurements is presented.
Abstract: The paper outlines a method allowing to compute the TEC with a precision of about 2–3 TECU and to detect Travelling Ionospheric Disturbances using GPS measurements. We describe the solar cycle dependance of the TEC and TIDs. Since the beginning of 1998, we have observed a stronger ionospheric activity due to the increasing solar activity. This ionospheric activity is characterized by larger TEC values which are regularly reaching the level of 60 TECU and by a larger number of Travelling Ionospheric Disturbances. During the winter 1999–2000, the mean daily TEC was above 45 TECU; at solar minimum the mean daily TEC is ranging from 4 TECU to 12 TECU. In January 2000 (close to solar maximum) more than 1300 events due to TID’s were detected: it is 6.5 more than in January 1996 (at solar minimum).

121 citations

Journal ArticleDOI
TL;DR: It is elucidated that Tec family kinases participate in at least two stages of FcγR-mediated phagocytosis: activation of Mac-1 during ingestion, and after phagosome formation, during which Btk and Tec potentially have distinct roles.
Abstract: Tec family nonreceptor tyrosine kinases are expressed by hematopoietic cells, activate phospholipase C (PLC)γ, and regulate cytoskeletal rearrangement, yet their role in FcγR-induced signaling and phagocytosis remains unknown. We demonstrate in this study that Bruton’s tyrosine kinase (Btk) and Tec, the only Tec kinases expressed by RAW 264.7 cells, are activated throughout phagocytosis. Activated Btk and Tec kinase accumulate at an early stage at the base of phagocytic cups and inhibition of their activity by the specific inhibitor LFM-A13 or expression by small interfering RNA significantly inhibited FcγR-induced phagocytosis. Similarly, a significant role for these kinases in phagocytosis was found in primary macrophages. FcγR-induced activation of Mac-1, which is required for optimal phagocytosis, was markedly inhibited and our findings suggest that the roles of kinases Btk and Tec in Mac-1 activation account for their functions in the early stages of phagocytosis. Initial activation of PLCγ2, the predominant PLC isoform in RAW 264.7 cells, is dependent on Syk. In contrast, a late and prolonged activation of PLCγ2 was dependent on Btk and Tec. We found accumulation of diacylglycerol (DAG), a PLCγ product, in phagosome membranes, and activated Btk, but not Tec, colocalized with phagosomal DAG. Inhibition of Tec family kinase activity increased the level of DAG in phagosomes, suggesting a negative regulatory role for Btk. Tec, in contrast, clustered at sites near phagosome formation. In summary, we elucidated that Tec family kinases participate in at least two stages of FcγR-mediated phagocytosis: activation of Mac-1 during ingestion, and after phagosome formation, during which Btk and Tec potentially have distinct roles.

120 citations

Journal ArticleDOI
TL;DR: It is proposed that SOCS- 1/JAB/SSI-1/TIP3 is a novel type of negative regulator to a subset of protein-tyrosine kinases to obscure how Tec relays the signals from cell surface receptors to the nucleus.

120 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023303
2022578
2021284
2020321
2019293
2018272