266 research outputs found

    A Large Along-Track Baseline Approach for Ground Moving Target Indication Using TanDEM-X

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    In the paper a new method for ground moving target indication (GMTI) using two satellites (i.e. the TerraSAR-X and the TanDEM-X satellite) together is presented. The along-track baseline between the satellites is chosen to be in the order of several kilometres, so that each satellite observes the same moving vehicles at different times in the order of one to several seconds. The proposed method allows the estimation of the ground velocity of the moving targets as well as the estimation of the broadside positions without the need of complex bistatic processing techniques

    Effects of glycation on blood protein interactions with nanomaterials: a biophysical and cytotoxicity study

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    When engineered nanoparticles (NPs) enter into a biological system, the proteins and biomolecules in the system adsorb to the NP surface to form a “protein corona” (PC). The PC greatly influences NP transformations, biological interactions, and cell response. Further complicating the development of NPs for biomedical applications, disease states alter the population of proteins and changes the biophysical features of individual proteins through posttranslational modifications. Here-in, we aim to understand how glycation of the PC, as in uncontrolled diabetes, alters the NP-PC interaction and toxicity by conducting biochemistry and cell toxicity experiments. We focus upon 40 and 80 nm citrate-coated silver nanoparticles and glycated and unmodified human serum albumin (HSA) as a model system. To investigate the impact of glycation on NP-PC interactions, we evaluate changes to NP size and surface charge, HSA secondary structure, and binding constants for the complex. Results indicate a stable system with no particle agglomeration or protein unfolding, an increase in surface charge, and dynamic binding. To investigate the impact of the PC and glycation on NP interactions with human cells, we investigate changes in proliferation of HepG2 cells with addition of the complex. Results indicate the protein corona increases the cytotoxicity of the NPs. Results will contribute to the body of research exploring how nanoparticles change when they enter human systems. In the long term this research will assist in developing NPs for medical applications, especially in a diabetic population

    Digital Beamforming and Traffic Monitoring Using the new FSAR System of DLR

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    In November 2006 the first X-band test flight of DLR’s new FSAR system has been performed successfully and in February 2007 the first flight campaign has been conducted for acquiring experimental multi-channel data of controlled ground moving targets. In the paper the performed experiments and the used setup of the FSAR X-band section are described and preliminary results in the field of ground moving target indication and digital beamforming are presented

    Impact of Road Vehicle Accelerations on SAR-GMTI Motion Parameter Estimation

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    In recent years many powerful techniques and algorithms have been developed to detect moving targets and estimate their motion parameters from single- or multi-channel SAR data. In case of single- and two-channel systems, most of the developed algorithms rely on analysis of the Doppler history. Nowadays it is known, that even small unconsidered across-track accelerations can bias the along-track velocity estimation. Since we want to monitor real and more complex traffic scenarios with a future traffic monitoring system like TRAMRAD, we must know which target accelerations we have to handle in reality. For this reason a common passenger car was equipped with an inertial measurement system and differential GPS to measure accelerations in all three dimensions during rush-hour traffic. In this paper the results of the acceleration measurements are presented and discussed. The standard deviations of the measured accelerations are in the order of 0.5 m/s2 for accelerations in driving direction and 0.6 m/s2 for radial accelerations. A theoretical analysis (which is verified by detailed simulations) of the Doppler slope shows also that at such high across-track accelerations a reliable estimation of the along-track velocity by means of a Doppler slope analysis without further information is unemployable in practice. Also oscillations of the car body along the vertical axis are investigated in this paper. From the field of vehicle dynamics it is known that the eigen frequencies of the car body are in the range from 0.7 to 2.0 Hz. Deflections in the order of one wavelength (X-band) or higher are possible at such frequencies. The simulation results for spaceborne SAR systems with integration times in the order of one second show that the shape and azimuth shift of the impulse response depend beside the oscillation frequency and the deflection also on the initial phase of the oscillation. However, at practical applications the main part of the energy could also be reflected by double bounce from the road surface. Thus, further investigations in the topic of vehicle oscillations by using real radar data are necessary. Finally, some basic ideas are presented which enable a reliable separation between along-track velocity and across-track acceleration. For example, the easiest way to separate both just mentioned motion parameters is the use of a road database, from which the information about the motion direction of the assigned vehicle can be extracted. Hence, the accuracy of along-track velocity estimation is mainly given by the accuracy of the estimated across-track velocity and the angle of the road section in relation to the flight path of the SAR platform

    Photodynamic therapy of prostate cancer by means of 5-aminolevulinic acid-induced protoporphyrin IX - In vivo experiments on the dunning rat tumor model

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    Objective: In order to expand the use of photodynamic therapy (PDT) in the treatment of prostate carcinoma (PCA), the aim of this study was to evaluate PDT by means of 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX ( PPIX) in an in vivo tumor model. Methods: The model used was the Dunning R3327 tumor. First of all, the pharmacokinetics and the localization of PPIX were obtained using fluorescence measurement techniques. Thereafter, PDT using 150 mg 5-ALA/kg b.w.i.v. was performed by homogenous irradiation of the photosensitized tumor (diode laser lambda = 633 nm). The tumors necrosis was determined histopathologically. Results: The kinetics of PPIX fluorescence revealed a maximum intensity in the tumor tissue within 3 and 4.5 h post-application of 5-ALA. At this time, specific PPIX fluorescence could be localized selectively in the tumor cells. The PDT-induced necrosis (n = 18) was determined to be 94 B 12% (range 60-100%), while the necrosis of the controls ( n = 12) differs significantly (p < 0.01), being less than 10%. Conclusion: These first in vivo results demonstrate the effective potential of 5-ALA-mediated PDT on PCA in an animal model. Copyright (C) 2004 S. Karger AG, Basel

    Hair cortisol concentrations in bovine neonates born to healthy and ill cows

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    The goal of this study was to investigate the hair cortisol concentration (HCC) in healthy and ill cows and their newborn calves. A total of 40 cows and their 42 newborn calves were divided into two groups: group 1 consisted of 19 clinically healthy cows and their 20 newborn calves, and group 2 comprised 21 cows that had had a chronic illness in the third trimester of gestation and their 22 newborn calves. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) system was used to measure the HCC in hair samples that were collected from the cows and calves on the day the calves were born. In both groups, the mean HCCs of the calves was significantly higher than that of the cows (group 1, 31,0 vs. 0,6 pg/mg; group 2, 19,4 vs. 0,8 pg/mg; P

    Handgrip Strength Values Depend on Tumor Entity and Predict 180-Day Mortality in Malnourished Cancer Patients.

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    BACKGROUND Cancer-related malnutrition is a prevalent condition associated with a loss of muscle mass and impaired functional status, leading to immunodeficiency, impaired quality of life and adverse clinical outcomes. Handgrip strength (HGS) is a practical measure to assess muscle strength in individual patients during clinical practice. However, HGS reference values refer to populations of healthy people, and population-specific values, such as those in the population of cancer patients, still need to be defined. METHODS Within a secondary analysis of a previous randomized controlled nutritional trial focusing on hospitalized cancer patients at risk for malnutrition, we investigated sex-specific HGS values stratified by age and tumor entity. Additionally, we examined the association between HGS and 180-day all-cause mortality. RESULTS We included data from 628 cancer patients, which were collected from eight hospitals in Switzerland. Depending on the age of patients, HGS varied among female patients from 7 kg to 26 kg and among male patients from 20.5 kg to 44 kg. An incremental decrease in handgrip strength by 10 kg resulted in a 50% increase in 180-day all-cause mortality (odds ratio 1.52 (95%CI 1.19 to 1.94), p = 0.001). CONCLUSION Our data provide evidence of the prognostic implications of HGS measurement in cancer patients and validate the prognostic value of handgrip strength in regard to long-term mortality. In addition, our results provide expected HGS values in the population of hospitalized malnourished cancer patients, which may allow better interpretation of values in individual patients
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