Estimating the solar meridional circulation by normal mode decomposition

The objective of this article is to use Fourier-Hankel decomposition as suggested earlier by Braun & Fan (1998) to estimate the integrated horizontal meridional flow velocity as a function of mode penetration depth, and to find ways of potentially improve this technique. We use a time series of 43200 (30 days) consecutive full-disk Dopplergrams obtained by the MDI (Michelson Doppler Imager) instrument aboard the SOHO (Solar Heliospheric Observatory) spacecraft in April 1999. We find averaged meridional flow estimates of 15 m/s for modes with a penetration depth in the upper 20 Mm of the solar convection zone. This reproduces the results of the earlier investigations. Moreover we conclude that this method has the potential to become a new technique to measure the meridional circulation in the deep convection zone, if some improvements will be applied.Comment: 5 pages, 2 figures, HELAS workshop proceedings "Roadmap for European Local Helioseismology", Nice, 25-27 September 200

Development of the TanDEM-X Calibration Concept: Analysis of Systematic Errors

The TanDEM-X mission, result of the partnership between the German Aerospace Center (DLR) and Astrium GmbH, opens a new era in spaceborne radar remote sensing. The first bistatic satellite synthetic aperture radar mission is formed by flying the TanDEM-X and TerraSAR-X in a closely controlled helix formation. The primary mission goal is the derivation of a high-precision global digital elevation model (DEM) according to High-Resolution Terrain Information (HRTI) level 3 accuracy. The finite precision of the baseline knowledge and uncompensated radar instrument drifts introduce errors that may compromise the height accuracy requirements. By means of a DEM calibration, which uses absolute height references, and the information provided by adjacent interferogram overlaps, these height errors can be minimized. This paper summarizes the exhaustive studies of the nature of the residual-error sources that have been carried out during the development of the DEM calibration concept. Models for these errors are set up and simulations of the resulting DEM height error for different scenarios provide the basis for the development of a successful DEM calibration strategy for the TanDEM-X mission

THE HEMATOPOIETIC CYTOKINE GRANULOCYTE-MACROPHAGE COLONY STIMULATING FACTOR IS INVOLVED IN COGNITIVE PROCESSING

Granulocyte/macrophage colony stimulating factor (GM-CSF) is a growth factor originally discovered in the hematopoietic system. Recently presence of GM-CSF and its receptor (GM-CSFR) was reported on CNS neurons. Here we investigated whether this system is involved in cognition by evaluating learning and memory formation in GM-CSF deficient (GMko) mice. In a complementary approach, GM-CSF signalling was bidirectionally manipulated specifically in the adult hippocampus by adeno-associated virus (AAV) mediated GM-CSF receptor alpha (GM-CSFRalpha) overexpression or knock-down. In GMko mice, broad cognitive deficits were observed in all behavioural paradigms tested. Animals showed impairments in fear memory to conditioned cue, in spatial learning in an active place avoidance paradigm, and in spatial memory and re-learning flexibility in the Morris Water Maze. Additionally, knock-outs also showed diminished exploratory drive. The inferior cognitive performance was not due to secondary factors such as motor function, inherent anxiety, or pain threshold levels. Corroborating these data, spatial memory of AAV-injected mice in the MWM was enhanced or impaired dependent on GM-CSFR alpha overexpression or knock-down, respectively. GMko mice showed diminished overall dendritic length and branching complexity in the dentate gyrus (DG) and reductions in both dendritic spine density and the percentage of mature spines in the hippocampus. Despite these morphological alterations and the strong memory deficits, induction of long-term potentiation (LTP) was not impaired in the hippocampus of knock-out mice, providing an example for the complicated relationship of LTP and memory performance. Collectively, these results suggest that GM-CSF signalling plays a major and hitherto unrecognized role in neuronal structural plasticity relevant to learning and memory. This finding is of particular therapeutic relevance, as GM-CSF readily passes the intact blood-brain barrier

Multistatic SAR Imaging: First Results of a Four Phase Center Experiment with TerraSAR-X and TanDEM-X

Multichannel synthetic aperture radar (SAR) imaging offers the possibility to overcome the pulse repetition frequency (PRF) constraints inherent to single-channel SAR systems. The multichannel approach enables the acquisition of wide swathes with high azimuth resolution. Using a constellation or swarm of small satellites, a cost efficient, faulttolerant system can be envisaged. This paper describes the first results of a multistatic four phase center experiment conducted with TerraSAR-X and TanDEM-X. The experiment is intended to increase the know-how and demonstrate the capabilities for the design of future SAR systems. Key challenges are addressed, the experimental acquisition is described and an evaluation approach is presented. Finally, first results focusing on the azimuth ambiguity performance are shown

Multistatic SAR Imaging: Comparison of Simulation Results and Experimental Data

Synthetic aperture radar (SAR) systems in a multistatic configuration are a promising candidate for future Earth observation and reconnaissance radar systems. They overcome the sampling constraints inherent to single-channel SAR systems. Thus, a multistatic SAR system enables the acquisition of high-resolution images while maintaining wide-swath coverage. Employing several small satellites instead of a single large one, a cost-efficient system with graceful degradation characteristics can be envisaged. Additionally, such a constellation or swarm of sensors offers interferometric and tomographic capabilities, which a single-satellite system is not able to provide. This paper shows results of multistatic experiments obtained with TerraSAR-X and TanDEM-X and compares these results with theoretical simulations. The key parameters analyzed are the Doppler spectrum and the azimuth ambiguity suppression

Measurements of a Multi Feed Reflector Antenna for SAR Systems Based on Digital Beam Forming

In the last years, the Synthetic Aperture Radar (SAR) systems evolution migrates toward the use of multi-channel systems based on Digital Beam Forming (DBF) techniques [1]. This tendendy allows fulfilling stringent SAR requirements, providing high spatial resolution within a wide swath. Moreover, the combination of DBF techniques with parabolic reflector antennas merges both flexibility and high antenna gain ending up in a high versatile system [2]. One of the main parts in a Digital Beam Forming (DBF) Synthetic Aperture Radar system is constituted by the antenna. An accurate characterization of the antenna radiation pattern is of high interest for the calibration of the system which guarantees the performance and versatility of the DBF network. This paper describes the measurements of a multi- feed single offset reflector antenna designed in X-band. The antenna is part of an on ground multi-channel radar system used to demonstrate ind investigate DBF techniques at HR/DL

TanDEM-X Acquisition Planning and DEM Performance in the Third Year of Operation

TanDEM-X is a spaceborne SAR mission with the goal to derive a global Digital Elevation Model (DEM). The two incorporated satellites fly in a close formation with distances of around 500 m. These small baselines form a single pass bistatic interferometer for accurate DEM acquisitions. The final DEM product will enter a new level of detail and accuracy on a global scale. The absolute height error shall be less than 10 m in a 90% confidence interval at a pixel spacing of 12 m. The vertical height specification for the TanDEM-X mission foresees a 90% point-to-point error of 2 m (4 m) for areas with predominant terrain slopes smaller than 20% (greater than 20%) for a 1° by 1° cell. This presentation gives an overview about the planning and the actual status of the global DEM acquisition. This includes the acquisition plan after the first two years of operation, i. e. two global coverages, including the acquisitions of the Antarctica and difficult terrain. Also, the actual performance status in terms of absolute and relative height error and the narrow relation between the DEM acquisition planning and the performance evaluation is presented

Bistatic Experiment Using TerraSAR-X and DLR’s new F-SAR System

A bistatic X-band experiment was successfully performed early November 2007. TerraSAR-X was used as transmitter and DLR’s new airborne radar system F-SAR, which was programmed to acquire data in a quasi-continuous mode to avoid echo window synchronization issues, was used as bistatic receiver. Precise phase and time referencing between both systems, which is essential for obtaining high resolution SAR images, was derived during the bistatic processing. Hardware setup and performance analyses of the bistatic configuration are pre-sented together with first processing results that verify the predicted synchronization and imaging performance

An integrated architecture for shallow and deep processing

We present an architecture for the integration of shallow and deep NLP components which is aimed at flexible combination of different language technologies for a range of practical current and future applications. In particular, we describe the integration of a high-level HPSG parsing system with different high-performance shallow components, ranging from named entity recognition to chunk parsing and shallow clause recognition. The NLP components enrich a representation of natural language text with layers of new XML meta-information using a single shared data structure, called the text chart. We describe details of the integration methods, and show how information extraction and language checking applications for realworld German text benefit from a deep grammatical analysis

Prognostic Risk Factors in Randomized Clinical Trials of Face-to-Face and Internet-Based Psychotherapy for Depression

Importance Variables such as severe symptoms, comorbidity, and sociodemographic characteristics (eg, low educational attainment or unemployment) are associated with a poorer prognosis in adults treated for depressive symptoms. The exclusion of patients with a poor prognosis from RCTs is negatively associated with the generalizability of research findings. Objective To compare the prognostic risk factors (PRFs) in patient samples of RCTs of face-to-face therapy (FTF) and internet-based therapy (IBT) for depression. Data Sources PsycINFO, Cochrane CENTRAL, and reference lists of published meta-analyses were searched from January 1, 2000, to December 31, 2021.Study SelectionRCTs that compared FTF (individual or group therapy) and IBT (guided or self-guided interventions) against a control (waitlist or treatment as usual) in adults with symptoms of depression were included. Data Extraction and Synthesis Data were extracted by 2 independent observers. The Cochrane revised risk-of-bias tool was used to assess the risk of bias. The study was preregistered with OSF Registries and followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Main Outcomes and Measures The primary outcome was the standardized mean difference (Hedges g effect size) in depressive symptoms at treatment termination (assessed with standard patient self-report questionnaires), with a positive standardized mean difference indicating larger improvements in the intervention compared with those in the control group. Meta-regression analyses were adjusted for the type of control group. Three preregistered and 2 exploratory sensitivity analyses were conducted. A prognostic risk index (PROG) was created that calculated the sum of 12 predefined individual indicators, with scores ranging from 0 to 12 and higher scores indicating that a sample comprised patients with poorer prognoses. Results This systematic review and meta-regression analysis identified 105 eligible RCTs that comprised 18 363 patients. In total, 48 studies (46%) examined FTF, and 57 studies (54%) examined IBT. The PROG was significantly higher in the RCTs of FTF than in the RCTs of IBT (FTF: mean [SD], 3.55 [1.75]; median [IQR], 3.5 [2.0-4.5]; IBT: mean [SD], 2.27 [1.66]; median [IQR], 2.0 [1.0-3.5]; z = −3.68, P < .001; Hedges g = 0.75; 95% CI, 0.36-1.15). A random-effects meta-regression analysis found no association of the PROG with the effect size. Sensitivity analyses with outliers excluded and accounting for risk of bias or small-study effects yielded mixed results on the association between the PROG and effect size. Conclusions and Relevance The findings of this systematic review and meta-regression analysis suggest that samples of RCTs of FTF vs IBT differ with regard to PRFs. These findings have implications for the generalizability of the current evidence on IBT for depression. More RCTs of internet-based interventions with clinically representative samples are needed, and the reporting of PRFs must be improved