6,524 research outputs found
Diabetic microangiopathy in Type 1 (insulin-dependent) diabetic patients after successful pancreatic and kidney or solitary kidney transplantation
To evaluate the beneficial effect of pancreatic grafting on peripheral microcirculation and long-term clinical outcome, we compared data of 28 Type 1 (insulin-dependent) diabetic patients either given a pancreatic and kidney graft simultaneously or given a solitary kidney graft (n=17). Peripheral microcirculation was estimated by transcutaneous oxygen pressure measurement (including reoxygenation potential after blood flow occlusion) and erythrocyte flow / velocity by a non-contact laser speckle method. All the measured parameters showed significant differences between diabetic and control subjects in the mean follow-up time of 49 (simultaneous pancreas and kidney transplantation) and 43 (solitary kidney transplantation) months. The data from patients after simultaneous pancreas and kidney transplantation revealed an improvement of transcutaneous oxygen pressure measurement (rise from 46±2 mm Hg to 63±3 mmHg), reoxygenation time (fall from 224±12s to 114±6s) and laser speckle measurement (rise from 4.2±1.7 to 5.6±1.8 relative units). The control group with solitary kidney transplantation did not show a positive evaluation. Data from patients after simultaneous pancreas and kidney transplantation revealed an improvement in transcutaneous oxygen pressure measurement, reoxygenation time and laser speckle measurement whereas the control group with solitary kidney transplantation did not show a positive evaluation. Improved microcirculation was more pronounced in patients with better microvascular preconditions. The results confirm that diabetic microangiopathy is positively influenced by pancreatic transplantation
Long-term results in pancreatic transplantation with special emphasis on the use of prolamine
Our pancreatic transplantation programme was initiated in 1979. Since then a total of 102 pancreas transplantations have been performed, blocking exocrine secretion using the duct occlusion technique with prolamine. Early non-immunological complications are frequent. The long-term results (9 years) in combined pancreas and kidney transplanted patients are satisfying: the survival rate for pancreas is 38% and 54% for kidney. Patient survival rate in this period is 85%. Beyond the first year post-transplant the exocrine activity disappears whereas the endocrine function remains well preserved
Aspects of the Mass Distribution of Interstellar Dust Grains in the Solar System from In-Situ Measurements
The in-situ detection of interstellar dust grains in the Solar System by the
dust instruments on-board the Ulysses and Galileo spacecraft as well as the
recent measurements of hyperbolic radar meteors give information on the
properties of the interstellar solid particle population in the solar vicinity.
Especially the distribution of grain masses is indicative of growth and
destruction mechanisms that govern the grain evolution in the interstellar
medium. The mass of an impacting dust grain is derived from its impact velocity
and the amount of plasma generated by the impact. Because the initial velocity
and the dynamics of interstellar particles in the Solar System are well known,
we use an approximated theoretical instead of the measured impact velocity to
derive the mass of interstellar grains from the Ulysses and Galileo in-situ
data. The revised mass distributions are steeper and thus contain less large
grains than the ones that use measured impact velocities, but large grains
still contribute significantly to the overall mass of the detected grains. The
flux of interstellar grains with masses is determined to
be . The comparison of radar data
with the extrapolation of the Ulysses and Galileo mass distribution indicates
that the very large () hyperbolic meteoroids detected by
the radar are not kinematically related to the interstellar dust population
detected by the spacecraft.Comment: 14 pages, 11 figures, to appear in JG
Mission design for LISA Pathfinder
Here we describe the mission design for SMART-2/LISA Pathfinder. The best
trade-off between the requirements of a low-disturbance environment and
communications distance is found to be a free-insertion Lissajous orbit around
the first co-linear Lagrange point of the Sun-Earth system L1, 1.5x 10^6 km
from Earth. In order to transfer SMART-2/LISA Pathfinder from a low Earth
orbit, where it will be placed by a small launcher, the spacecraft carries out
a number of apogee-raise manoeuvres, which ultimatively place it to a parabolic
escape trajectory towards L1. The challenges of the design of a small mission
are met, fulfilling the very demanding technology demonstration requirements
without creating excessive requirements on the launch system or the ground
segment.Comment: 7 pages, 6 figures, 5th International LISA Symposium, see
http://www.landisoft.de/Markus-Landgra
Potential of the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor for the monitoring of terrestrial chlorophyll fluorescence
Global monitoring of sun-induced chlorophyll fluorescence (SIF) is improving our knowledge about the photosynthetic functioning of terrestrial ecosystems. The feasibility of SIF retrievals from spaceborne atmospheric spectrometers has been demonstrated by a number of studies in the last years. In this work, we investigate the potential of the upcoming TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor satellite mission for SIF retrieval. TROPOMI will sample the 675–775 nm spectral window with a spectral resolution of 0.5 nm and a pixel size of 7 km × 7 km. We use an extensive set of simulated TROPOMI data in order to assess the uncertainty of single SIF retrievals and subsequent spatio-temporal composites. Our results illustrate the enormous improvement in SIF monitoring achievable with TROPOMI with respect to comparable spectrometers currently in-flight, such as the Global Ozone Monitoring Experiment-2 (GOME-2) instrument. We find that TROPOMI can reduce global uncertainties in SIF mapping by more than a factor of 2 with respect to GOME-2, which comes together with an approximately 5-fold improvement in spatial sampling. Finally, we discuss the potential of TROPOMI to map other important vegetation parameters at a global scale with moderate spatial resolution and short revisit time. Those include leaf photosynthetic pigments and proxies for canopy structure, which will complement SIF retrievals for a self-contained description of vegetation condition and functioning
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