Ionospheric estimation is becoming more and more important for the new multifrequency positioning algorithms, since they can help to improve greatly the convergence time for acquiring a good ...positioning error. In this paper, an open source tool to estimate precise ionospheric estimates is presented, namely ESA UGI (Unified-GNSS-Ionosphere). The presentation is done jointly with a methodology to test ionospheric model using a modified NeQuick to generate synthetic data. The results with different option of the ESA UGI shows that it has a good performance below 1 TECU (Total Electron Content Units) in vTEC (vertical Total Electron Content) RMS (Root Mean Squared) for European networks, around 2 TECU in a well-covered African region and between 1 and 6 TECU globally with this synthetic data. It shows as well the capability of changing between different ionosphere models (voxel, multilayer and spherical harmonics) and configuration options. Finally, a test with uncombined PPP actual data is presented showing that instantaneous convergence below 30 cm in 3D RMS position error are achievable in a well sounded area in Europe.
Severe infectious diseases that require surgery after acupuncture therapy are quite rare. There are only a few cases of pyomyositis following acupuncture reported in the literature. This paper ...presents a case of cervical pyomyositis developed after such treatment.
A 36-year-old man presented with swelling and pain in the posterior cervical region as well as high fever and torticollis, after having received three sessions of acupuncture therapy during the preceding weeks aimed to treat his neck stiffness. Ultrasound guided fine needle aspiration (FNA) and contrast-enhanced Computed Tomography (CT) were performed, which showed a large abscess along the paraspinal muscles. The symptoms were resolved after surgical treatment and antibiotherapy.
Although highly infrequent, pyomyositis is a probable complication of acupuncture. In order to minimise the risk of complications, strict hygenic precautions and knowledge of the human anatomy are mandatory to decrease the rate of complications of acupuncture.
Dual frequency Global Positioning System (GPS) receivers provide integrated total electron content (TEC) along the ray path (slant TEC, affected by a bias). By inverting this observable, it is ...possible to obtain the vertical total electron content with some assumptions about the horizontal structure of the ionosphere.
The large number of permanent receivers distributed around the world provide enough information to obtain such TEC observables with high spatial and temporal resolutions. Nevertheless, the geometry (mainly vertical) of the ground GPS observations does not allow to solve the vertical structure of electron density of the ionosphere.
Mixing different kinds of complementary data in a tomographic context helps to overcome this problem. Several works have obtained successful results achieved by combining occultation and ground GPS data to estimate the local three-dimensional structure of ionospheric electron density. This paper proposes the use of just ground data to obtain similar or better results. To do this, the ground GPS data are mixed with vertical profiles of electron density derived from ionosonde data instead of GPS occultation observations.
In this paper, the complementarity between vertical profiles of electron density (estimated using the NeQuick model) and ground GPS data (from GPS IGS permanent network) are shown as well as the performance of the resulting combination.
Validation of the GPS TEC maps with TOPEX data Orús, R.; Hernández-Pajares, M.; Juan, J.M. ...
Advances in space research,
2003, 2003-1-00, 20030101, Volume:
31, Issue:
3
Journal Article
Peer reviewed
The existence of a worldwide IGS (International GPS Service) permanent network of dual frequency receivers, makes feasible the computation of Global Ionospheric Maps (GIM's) of vertical Total ...Electron Content (TEC). The GIM's computed by the IGS Associate Analisys Centers (IAAC's) are being computed in a daily basis since 1998. The comparison with other kinds of forecast GIM's (computed from the International Reference Ionosphere (IRI) model and the GPS broadcast model) show that the GPS GIM's provide better accuracy and are useful for different applications such as navigation and time transfer. In this context, the performance of both kind of models are presented in this work in order to determine the accuracy of the different Global Ionospheric Maps. This is done by comparing with the TOPEX data that provides an indepentent and precise vertical TEC determination over the oceans (at the level of few TECU) which provides a way of validating the GIM's.
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