Results 71 to 80 of about 1,523 (198)

The mechanisms in glucose metabolism of aging hippocampus

Ibrain, Volume 11, Issue 4, Page 457-475, Winter 2025.
Cognitive decline in elders stems from the irreversible loss and functional decline of neurons, with the hippocampus being particularly susceptible to age‐related neuronal deterioration. Glucose acts as the primary fuel for the brain, and a constant provision of glucose to the hippocampus is essential for memory and cognitive functions.
Rui He, Fuxing Zhao, Zhiyu Yang, Tingting Wang, Yaohui Zhang, Jinglan Quan, Gaohong Zhu   +6 more
wiley   +1 more source

Integer Ambiguity Resolution for Multi-GNSS and Multi-Signal Raw Phase Observations [PDF]

, 2020
The continuous modernisation of existing Global Navigation Satellite Systems (GNSS) and the development of new systems with a multitude of different carrier frequencies and a variety of signal modulations creates a true multi-GNSS and multi-signal ...
Reckeweg, Florian
core   +1 more source

Volcano‐Tectonic Crisis of Mayotte (2018–2022): A Deformation Model for Geodetic Applications

Journal of Geophysical Research: Solid Earth, Volume 130, Issue 10, October 2025.
Abstract Volcano‐tectonic unrest during the 2018–2022 crisis of Mayotte (Comoros archipelago) generated an island‐wide surface displacement reaching ∼ ${\sim} $20 cm, with a relative (internal) deformation of the island of ∼ ${\sim} $10 cm. Correcting for these displacements, which exceed the required accuracy of geodetic network reference coordinates,
Raphaël Grandin, Xavier Collilieux, Inès Pasquier, Olivier Jamet   +3 more
wiley   +1 more source

Influence of erosive drivers on the morphology of gullies in the Pampa biome, Southern Brazil

Earth Surface Processes and Landforms, Volume 50, Issue 12, 30 September 2025.
The gullies in the pampa biome of Southern Brazil have different forms and intensity of erosion, despite being spatially close and sometimes this difference is observed within the same gully. The type of soil and rock material proved to be the determining factor in differentiating the shape of the gullies studied, with significant differences in the ...
Lucas Krein Rademann, Romario Trentin, Luis Eduardo de Souza Robaina   +2 more
wiley   +1 more source

A Multi-Epoch Processing Strategy for PPP-RTK Users

, 2023
AbstractThe present contribution aims to address why the stochastic model of the PPP-RTK user-filter is misspecified, and how one can limit the precision-loss associated with user parameter solutions. By developing tools for measuring the stated precision-loss under existing formulations of the user’s Kalman filter, we propose an alternative ...
Khodabandeh, A, Teunissen, PJG, Psychas, D   +2 more
openaire   +2 more sources

Optimizing PPP Performance by Incorporating ZWD Constraints Derived From Data Assimilation

Earth and Space Science, Volume 12, Issue 8, August 2025.
Abstract One of the primary error sources limiting the performance of the Precise Point Positioning (PPP) technique is the atmospheric wet delay, caused by the presence of water vapor in the lower atmosphere. Accurately representing this parameter is crucial for improving the initialization and accuracy of satellite‐based positioning techniques ...
Masoud Dehvari, Saeed Farzaneh, Ehsan Forootan   +2 more
wiley   +1 more source

Towards PPP-RTK: Ambiguity resolution in real-time precise point positioning [PDF]

Advances in Space Research, 2011
Abstract Integer ambiguity resolution at a single station can be achieved by introducing predetermined uncalibrated phase delays (UPDs) into the float ambiguity estimates of precise point positioning (PPP). This integer resolution technique has the potential of leading to a PPP-RTK (real-time kinematic) model where PPP provides rapid convergence to a
Geng, J., Teferle, Felix Norman, Meng, X., Dodson, A. H.   +3 more
openaire   +2 more sources

Real‐Time Regional Ionosphere Modeling With RFR‐Net Over China

Space Weather, Volume 23, Issue 8, August 2025.
Abstract The mid‐to‐low‐latitude ionosphere, influenced by phenomena such as the Equatorial Ionization Anomaly, responds more sensitively to changes in solar activity, which negatively affect the transmission of various electromagnetic signals. Moreover, next‐generation technologies, particularly Precise Point Positioning‐Real‐Time Kinematic (PPP‐RTK),
Mengfei Sun, Tong Liu, Zonghua Ding, Jian Liu, Yanshi Huang, Kun Zhang, Shengliang Fang, Shizhong Li, Qinglei Kong, Bo Chen   +9 more
wiley   +1 more source

A 4D tomographic ionospheric model to support PPP-RTK

Journal of Geodesy, 2019
Successful implementation of integer ambiguity resolution enabled precise point positioning (aka PPP-RTK) algorithms is inextricably linked to the ability of a user to perform near real-time positioning by quickly and reliably resolving the integer carrier-phase ambiguities.
G. Olivares-Pulido, M. Terkildsen, K. Arsov, P. J. G. Teunissen, A. Khodabandeh, V. Janssen   +5 more
openaire   +4 more sources

Performance of PPP and PPP-RTK with new-generation GNSS constellations and signals

Satellite Navigation
The expansion of Global Navigation Satellite Systems (GNSS) and Regional Navigation Satellite Systems (RNSS), along with broadcasting of additional signals, offers more options for Precise Point Positioning (PPP). Utilizing a number of constellations and
Xiaohong Zhang, Yuhang Yang, Haochen Yang, Xiaodong Ren, Xiaojing Lin, Xuan Le, Xin Li   +6 more
doaj   +1 more source