Contributions of the immune system to the pathophysiology of traumatic brain injury - evidence by intravital microscopy

Traumatic brain injury (TBI) results in immediate brain damage that is caused by the mechanical impact and is non-reversible. This initiates a cascade of delayed processes which cause additional-secondary-brain damage. Among these secondary mechanisms, the inflammatory response is believed to play an important role, mediating actions that can have both protective and detrimental effects on the progression of secondary brain damage. Histological data generated extensive information; however, this is only a snapshot of processes that are, in fact, very dynamic. In contrast, in vivo microscopy provides detailed insight into the temporal and spatial patterns of cellular dynamics. In this review, we aim to summarize data which was generated by in vivo microscopy, specifically investigating the immune response following brain trauma, and its potential effects on secondary brain damage

Signal Dependent Non-Linearity Calibration of an Imaging Spectrometer

We show the signal dependent non-linearity calibration of a HySpex VNIR-1600 hyperspectral sensor using the light addition method. The method has the advantage that a wide spectral range can be calibrated simultaneously with high accuracy. We developed a new setup that uses two lamps, which are coupled into an integrating sphere. The setup can illuminate the whole field of view simultaneously. Additionally, we enhanced the method to allow a denser sampling of the calibration curve than conventionally possible. The results show non-linearities up to 15% dependent on the detector area. After correction, the remaining error is negligible

A privacy-preserving and power-efficient bicycle tracking scheme for theft mitigation

© 2016 IEEE. Bicycle theft is a big problem in places such as university towns, where bicycles offer one of the most costefficient and quick ways for students to move around. For example, 1,200 bicycles are stolen yearly in Göttingen, with more than 300,000 being reported as stolen in the whole of Germany during 2014. We present a power efficient architecture to track the locations of stolen bicycles using opportunistic communication with collection nodes placed in high traffic spots, that can be used to find stolen and lost bicycles. At the same time, the scheme is designed to prevent a loss of privacy for the owners of bicycles that have not been marked as stolen, while also reducing power usage during times where bicycles are under the control of their proper owners.We also show the feasibility of our approach using a simplified implementation using IRIS nodes, with a university campus serving as a testbed

LimnoVIS - A Robotic Surface Vehicle for Spectral Measurements in Inland Waters

Spectral measurements in aquatic remote sensing are usually carried out from ships, boats or stationary platforms. While the latter only covers a single location, mobile platforms can introduce significant errors due to unexpected movement (drift and rotation), reflection and shadowing effects from the ship’s hull, superstructures and the personnel conducting the measurements. To overcome these caveats, we developed the low-profile robotic platform LimnoVIS that can be operated autonomously or remotely controlled and is capable of keeping its position and orientation accurately through its omnidirectional maneuverability. The onboard measurement system comprises a VIS/NIR spectrometer (350-880 nm, 1 nm resolution) which is connected to four different optics via a fiber optical switch. This allows for rapid subsequent measurement of upwelling radiance above and under water, sky radiance and downwelling irradiance using reflectance standards or a cosine corrector, all by the same spectrometer. LimnoVIS carries also a profiler, which can be lowered by up to 30 m. It is equipped with a spectrometer and a tiltable diffusor for measuring benthic reflectance, LED and halogen lamps, a laser range finder, a camera, and sensors for temperature and pressure. Multiple onboard cameras with recording and live viewing capabilities are used for navigation, visual supervision and documentation of the measurements and for compiling shallow-water orthomosaics. Furthermore, LimnoVIS is equipped with a sonar for deriving bathymetry in the range of 0.5 to 30 m

Microvasospasms After Experimental Subarachnoid Hemorrhage Do Not Depend on Endothelin A Receptors

Background and Purpose-Perturbations in cerebral microcirculation (eg, microvasospasms) and reduced neurovascular communication determine outcome after subarachnoid hemorrhage (SAH). ET-1 (endothelin-1) and its receptors have been implicated in the pathophysiology of large artery spasms after SAH;however, their role in the development of microvascular dysfunction is currently unknown. Here, we investigated whether inhibiting ETA (endothelin A) receptors can reduce microvasospasms after experimentally induced SAH. Methods-SAH was induced in male C57BL/6 mice by filament perforation of the middle cerebral artery. Three hours after SAH, a cranial window was prepared and the pial and parenchymal cerebral microcirculation was measured in vivo using two-photon microscopy before, during, and after administration of the ETA receptor inhibitor clazosentan. In separate experiments, the effect of clazosentan treatment on neurological outcome was measured 3 days after SAH. Results: Clazosentan treatment had no effect on the number or severity of SAH-induced cerebral microvasospasms nor did it affect neurological outcome. Conclusions: Our results indicate that ETA receptors, which mediate large artery spasms after SAH, do not seem to play a role in the development of microarterial spasms, suggesting that posthemorrhagic spasms are mediated by distinct mechanisms in large and small cerebral vessels. Given that cerebral microvessel dysfunction is a key factor for outcome after SAH, further research into the mechanisms that underlie posthemorrhagic microvasospasms is urgently needed

In vivo temporal and spatial profile of leukocyte adhesion and migration after experimental traumatic brain injury in mice

Background: Leukocytes are believed to be involved in delayed cell death following traumatic brain injury (TBI). However, data demonstrating that blood-borne inflammatory cells are present in the injured brain prior to the onset of secondary brain damage have been inconclusive. We therefore investigated both the interaction between leukocytes and the cerebrovascular endothelium using in vivo imaging and the accumulation of leukocytes in the penumbra following experimentally induced TBI. Methods: Experimental TBI was induced in C57/Bl6 mice (n = 42) using the controlled cortical impact (CCI) injury model, and leukocyte-endothelium interactions (LEI) were quantified using both intravital fluorescence microscopy (IVM) of superficial vessels and 2-photon microscopy of cortical vessels for up to 14 h post-CCI. In a separate experimental group, leukocyte accumulation and secondary lesion expansion were analyzed in mice that were sacrificed 15 min, 2, 6, 12, 24, or 48 h after CCI (n = 48). Finally, leukocyte adhesion was blocked with anti-CD18 antibodies, and the effects on LEI and secondary lesion expansion were determined 16 (n = 12) and 24 h (n = 21), respectively, following TBI. Results: One hour after TBI leukocytes and leukocyte-platelet aggregates started to roll on the endothelium of pial venules, whereas no significant LEI were observed in pial arterioles or in sham-operated mice. With a delay of >4 h, leukocytes and aggregates did also firmly adhere to the venular endothelium. In deep cortical vessels (250 mu m) LEIs were much less pronounced. Transmigration of leukocytes into the brain parenchyma only became significant after the tissue became necrotic. Treatment with anti-CD18 antibodies reduced adhesion by 65\%; however, this treatment had no effect on secondary lesion expansion. Conclusions: LEI occurred primarily in pial venules, whereas little or no LEI occurred in arterioles or deep cortical vessels. Inhibiting LEI did not affect secondary lesion expansion. Importantly, the majority of migrating leukocytes entered the injured brain parenchyma only after the tissue became necrotic. Our results therefore suggest that neither intravascular leukocyte adhesion nor the migration of leukocytes into cerebral tissue play a significant role in the development of secondary lesion expansion following TBI

ProGIRH-DLR: Remote sensing of water quality in the Mantaro River basin through spaceborne and ground-based acquisition of multi- and hyperspectral data

Peru is amongst the most affected countries by climate change in the world, with severe consequences on the availability of water across the country. The GIZ funded project "Multisectoral management of water resources in the Mantaro River basin" (ProGIRH) aims to improve the integrated and climate-sensitive water resource management in the Mantaro River basin. Within this framework, an IMF Team supports the Peruvian national water authority (ANA) in establishing remote sensing methodologies as a complement to traditional sampling-based water analysis. With a permanent focus on capacity building of the regional partners, the Team combines multi- and hyperspectral satellite imagery with in-situ spectral data, in order to define the possibilities and technical requirements necessary to establish a self-dependent and locally managed long-term observation of water quality and availability