Observations of Upper Mesosphere Temperatures on Venus and Evaluation of Mid-Infrared Detectors for the Tuneable Infrared Heterodyne Spectrometer (THIS)

Infrared heterodyne spectroscopy today is an inherent part in planetary atmosphere observations. It is based on the superposition of the observed signal to a local oscillator and provides highest possible spectral resolution. Non-thermal emission of CO2 in the upper mesosphere of Venus was discovered by the NASA Infrared Heterodyne Spectrometer (IRHS) in the 1970s and was repeatedly target of observations since then. In the course of this thesis, data of with IRHS, its successor HIPWAC and the Cologne Tuneable Heterodyne Infrared Spectrometer (THIS) was taken or analysed. From the measured line widths the kinetic temperature of the atmosphere at the emission altitude of around 115 km could be determined. Observed temperatures are generally higher than predicted by the Venus International Reference Atmosphere (VIRA). VIRA is a empirical model mainly based on data of the Pioneer Venus space mission and exhibits only a limited data set. Other ground-based observations as well as results from Venus Express confirm the warm atmosphere at similar altitudes. At the day side of Venus and at this specific altitude, infrared heterodyne spectroscopy is currently the only method to observe temperatures. Another result is the high variability of the observed atmosphere which is not expected by the VIRA model but which was also seen in earlier mm-wavelength observations. The obtained results also set new constraints for modern global circulation models. Improving those models will lead to a improved knowledge of planetary atmospheres. As all those models are based on the Earth atmosphere model, our observations might subsequently lead to a better understanding of the terrestrial climate as well. The second part of this thesis deals with the evaluation of possible detectors for THIS to expand the wavelength coverage to longer wavelengths. Many atomic and molecular lines could be targeted within the solar system and beyond. The main target will be cold molecular hydrogen in the interstellar medium which is of highest importance in astrophysical questions concerning star forming, dark matter and cosmology. For this reason first tests at 17 micrometer wavelength were done in the course of this work

Selective Large-Area Retinal Pigment Epithelial Removal by Microsecond Laser in Preparation for Cell Therapy

Purpose: Cell therapy is a promising treatment for retinal pigment epithelium (RPE)- associated eye diseases such as age-related macular degeneration. Herein, selective microsecond laser irradiation targeting RPE cells was used for minimally invasive, large- area RPE removal in preparation for delivery of retinal cell therapeutics. Methods: Ten rabbit eyes were exposed to laser pulses 8, 12, 16, and 20 μs in duration (wavelength, 532 nm; top-hat beam profile, 223 × 223 μm2). Post-irradiation retinal changes were assessed with fluorescein angiography (FA), indocyanine green angiogra- phy (ICGA), and optical coherence tomography (OCT). RPE viability was evaluated with an angiographic probit model. Following vitrectomy, a subretinal injection of balanced salt solution was performed over a lasered (maximum 13.6 mm2) and untreated control area. Bleb retinal detachment (bRD) morphology was then evaluated by intraoperative OCT. Results: Within 1 hour after irradiation, laser lesions showed FA and ICGA leakage. OCT revealed that large-area laser damagewas limited to the RPE. The angiographic median effective dose irradiation thresholds (ED50)were45μJ(90 mJ/cm2)at8μs,52μJ(104 mJ/cm2) at 12 μs, 59 μJ (118 mJ/cm2)at16μs,and71μJ(142mJ/cm2) at 20 μs. Subretinal injection over the lasered area resulted in a controlled, shallowbRD rise, whereas control blebs were convex in shape, with less predictable spread. Conclusions: Large-area, laser-based removal ofhost RPEwithout visible photoreceptor damage is possible and facilitates surgical retinal detachment. Translational Relevance: Selective microsecond laser-based, large-area RPE removal prior to retinal cell therapy may reduce iatrogenic trauma. Introductio

Nachhaltig studieren, arbeiten, leben in Reutlingen

Einige Ideen, Erfahrungen und Realitäten für die Studierenden und Bürger in Reutlingen. Zusammengestellt von 50 Studierenden 2020/21 und aus Beiträgen von 40 Institutionen und Unternehmen in und um Reutlingen. Ein Versuch, sehr konkret am Tatsächlichen zu erklären, was zu mehr Nachhaltigkeit führt, in Reutlingen. Dabei bleibt nicht aus, auch auf Schwachstellen hinzuweisen. Wenn Studierende und Bürger in den nächsten Jahren bewusst zu mehr Nachhaltigkeit bereit sind, so sind sie mit den Ideen und Realitäten in diesem Projekt auf einem guten Weg

Heat Generation During Ablation of Porcine Skin with Erbium:YAG Laser vs a Novel Picosecond Infrared Laser

Importance: Despite significant advances in surgery, most surgical tools remain basic. Lasers provide a means of precise surgical ablation, but their clinical use has remained limited because of undesired thermal, ionizing, or acoustic stress effects leading to tissue injury. A novel ultrafast, nonionizing, picosecond infrared laser (PIRL) system has recently been developed and is capable, in theory, of ablation with negligible thermal or acoustic stress effects.Objective: To measure and compare heat generation by means of thermography during ablation of ex vivo porcine skin by conventional microsecond-pulsed erbium:YAG (Er:YAG) laser and picosecond infrared laser (PIRL).Design and Setting: This study was conducted in an optics laboratory and used a pretest-posttest experimental design comparing 2 methods of laser ablation of tissue with each sample acting as its own control.Intervention: Ex vivo porcine skin was ablated in a 5-mm line pattern with both Er:YAG laser and PIRL at fluence levels marginally above ablation threshold (2 J/cm$^{2}$ and 0.6 J/cm$^{2}$, respectively).Main Outcomes and Measures: Peaks and maxima of skin temperature rises were determined using a thermography camera. Means of peak temperature rises were compared using the paired sample $\mathit{t}$ test. Ablation craters were assessed by means of digital microscopy.Results: Mean peak rise in skin surface temperature for the Er:YAG laser and PIRL was 15.0°C and 1.68°C, respectively (P < .001). Maximum peak rise in skin surface temperature was 18.85°C for the Er:YAG laser and 2.05°C for the PIRL. Ablation craters were confirmed on digital microscopy.Conclusions and Relevance Picosecond infrared laser ablation results in negligible heat generation, considerably less than Er:YAG laser ablation, which confirms the potential of this novel technology in minimizing undesirable thermal injury associated with lasers currently in clinical use

Ultrafast thin-disk multipass amplifier with 720 mJ operating at kilohertz repetition rate for applications in atmospheric research

We present an ultrafast thin-disk based multi pass amplifier operating at a wavelength of 1030 nm, designed for atmospheric research in the framework of the Laser Lightning Rod project. The CPA system delivers a pulse energy of 720 mJ and a pulse duration of 920 fs at a repetition rate of 1 kHz. The 240 mJ seed pulses generated by a regenerative amplifier are amplified to the final energy in a multipass amplifier via four industrial thin-disk laser heads. The beam quality factor remains ∼2.1 at the output. First results on horizontal long-range filament generation are presented

Second and third harmonic generation from simultaneous high peak- and high average-power thin disk laser

International audienceWe report Second Harmonic Generation (SHG) and Third Harmonic Generation (THG) energy conversion efficiencies up to 59% and 27%, respectively, for laser pulses simultaneously delivering high peak power in the sub-TW range and average powers in the sub-kW range. No damage or efficiency decrease is observed after more than 100 h operation time. The resulting high-energy visible and near-UV pulses are suitable for applications, such as lightning control, material analysis and machining, or OPCPA pumping

An angiogenic role for the human peptide antibiotic LL-37/hCAP-18

Antimicrobial peptides are effector molecules of the innate immune system and contribute to host defense and regulation of inflammation. The human cathelicidin antimicrobial peptide LL-37/hCAP-18 is expressed in leukocytes and epithelial cells and secreted into wound and airway surface fluid. Here we show that LL-37 induces angiogenesis mediated by formyl peptide receptor–like 1 expressed on endothelial cells. Application of LL-37 resulted in neovascularization in the chorioallantoic membrane assay and in a rabbit model of hind-limb ischemia. The peptide directly activates endothelial cells, resulting in increased proliferation and formation of vessel-like structures in cultivated endothelial cells. Decreased vascularization during wound repair in mice deficient for CRAMP, the murine homologue of LL-37/hCAP-18, shows that cathelicidin-mediated angiogenesis is important for cutaneous wound neovascularization in vivo. Taken together, these findings demonstrate that LL-37/hCAP-18 is a multifunctional antimicrobial peptide with a central role in innate immunity by linking host defense and inflammation with angiogenesis and arteriogenesis