Matter wave interferometry in microgravity

Quantensensoren auf Basis ultra-kalter Atome sind gegenwärtig auf dem Weg ihre klassischen Pendants als Messintrumente sowohl in Präzision als auch in Genauigkeit zu überholen, obwohl ihr Potential noch immer nicht vollständig ausgeschöpft ist. Die Anwendung von Quantensensortechnologie wie Materiewelleninterferometern im Weltraum wird ihre Sensitivität weiter steigen lassen, sodass sie potentiell die genauesten erdbasierten Systeme um mehrere Grössenordnungen übertreffen könnten. Mikrogravitationsplattformen wie Falltürme, Parabelflugzeuge und Höhenforschungsraketen stellen exzellente Testumgebungen für zukünftge atominterferometrische Experimente im Weltraum dar. Andererseits erfordert ihre Nutzung die Entwicklung von Schlüsseltechnologien, die hohe Standards in Bezug auf mechanische und thermische Robustheit, Autonomie, Miniaturisierung und Redundanz erfüllen müssen. In der vorliegenden Arbeit wurden erste Interferometrieexperimente mit degenerieten Quantengasen in Schwerelosigkeit im Rahmen des QUANTUS Projektes durchgeführt. In mehr als 250 Freifall-Experimenten am Bremer Fallturm konnte die Präparation, freie Entwicklung und Phasenkohärenz eines Rubidium Bose- Einstein Kondensates (BEC) auf makroskopischen Zeitskalen von bis zu 2 s untersucht werden. Dazu wurde ein BEC-Interferometer mittels Bragg-Strahlteilern in einen Atomchip-basierten Aufbau implementiert. In Kombination mit dem Verfahren der Delta-Kick Kühlung (DKC) konnte die Expansionsrate der Kondensate weiter reduziert werden, was zur Beobachtung von effektiven Temperaturen im Bereich von 1 nK führte. In einem Interferometer mit asymetrischer Mach-Zehnder Geometrie konnten Interferenzstreifen mit hohem Kontrast bis zu einer Verweildauer von 2T = 677 ms untersucht werden.State-of-the-art cold atomic quantum sensors are currently about to outpace their classical counterparts in precision and accuracy, but are still not exploiting their full potential. Utilizing quantum-enhanced sensor technology such as matter wave interferometers in the unique environment of microgravity will tremendously increase their sensitivity, ultimately outperforming the most accurate groundbased systems by several orders of magnitude. Microgravity platforms such as drop towers, zero-g airplanes and sounding rockets are excellent testbeds for advanced interferometry experiments with quantum gases in space. In return, they impose demanding requirements on the payload key technologies in terms of mechanical and thermal robustness, remote control, miniaturization and redundancy. In this work, first interferometry experiments with degenerate quantum gases in zero-g environment have been performed within the QUANTUS project. In more than 250 free fall experiments operated at the drop tower in Bremen, preparation, free evolution and phase coherence of a rubidium Bose-Einstein condensate (BEC) on macroscopic timescales of up to 2 s have been explored. To this end, a BEC interferometer using first-order Bragg diffraction was implemented in an atomchip based setup. Combined with delta-kick cooling (DKC) techniques to further slow down the expansion of the atomic cloud, effective temperatures of about 1 nK have been reached. With an asymmetrical Mach-Zehnder geometry, high-contrast interferometric fringes were observed up to a total time in the interferometer of 2T = 677 ms

Screening of retroviral cDNA libraries for factors involved in protein phosphorylation in signaling cascades

We report a novel approach that allows for the rapid identification of proteins mediating phosphorylation in signaling cascades after specific stimulation. As a proof of concept, we used the interferon- γ (IFN-γ)-induced phosphorylation of signal transducer and activator of transcription-1 (Stat1) in a human promonocytic cell line, which was previously shown to be deficient in this signaling pathway. By using retroviral cDNA expression libraries, transduced selector cells expressing single cDNAs were stimulated with IFN-γ, then fixed, permeabilized and stained intracellularly for phospho-Stat1 levels. Cells responding to the stimulation, which showed increased levels of phosphorylated Stat1, were enriched using fluorescence activated cell sorting (FACS). Genomic DNA was isolated from the enriched cell population and served as a template for cDNA amplification using PCR. After only one round of selection, a cDNA encoding the β-chain of the IFN-γ receptor (IFNGR2) was obtained and demonstrated to restore the selected phenotype. The approach now allows one to use phospho-events as reporters, alone or in tandem, for screening of signaling network states, overcoming a prior need to rely on the reporter genes that are often only indirect measures of phenotypes desired in a screen

COP9 signalosome component JAB1/CSN5 is necessary for T cell signaling through LFA-1 and HIV-1 replication.

To determine critical host factors involved in HIV-1 replication, a dominant effector genetics approach was developed to reveal signaling pathways on which HIV-1 depends for replication. A large library of short peptide aptamers was expressed via retroviral delivery in T cells. Peptides that interfered with T cell activation-dependent processes that might support HIV-1 replication were identified. One of the selected peptides altered signaling, lead to a difference in T cell activation status, and inhibited HIV-1 replication. The target of the peptide was JAB1/CSN5, a component of the signalosome complex. JAB1 expression overcame the inhibition of HIV-1 replication in the presence of peptide and also promoted HIV-1 replication in activated primary CD4(+) T cells. This peptide blocked physiological release of JAB1 from the accessory T cell surface protein LFA-1, downstream AP-1 dependent events, NFAT activation, and HIV-1 replication. Thus, genetic selection for intracellular aptamer inhibitors of host cell processes proximal to signals at the immunological synapse of T cells can define unique mechanisms important to HIV-1 replication

Propionibacterium acnes Induces an IL-17 Response in Acne Vulgaris that Is Regulated by Vitamin A and Vitamin D.

Acne vulgaris is the most common skin disorder affecting millions of people worldwide and inflammation resulting from the immune response targeting Propionibacterium acnes has a significant role in its pathogenesis. In this study, we have demonstrated that P. acnes is a potent inducer of T helper 17 (Th17) and Th1, but not Th2 responses in human peripheral blood mononuclear cells (PBMCs). P. acnes stimulated expression of key Th17-related genes, including IL-17A, RORα, RORc, IL-17RA, and IL-17RC, and triggered IL-17 secretion from CD4(+), but not from CD8(+) T cells. Supernatants from P. acnes-stimulated PBMCs were sufficient to promote the differentiation of naive CD4(+)CD45RA T cells into Th17 cells. Furthermore, we found that the combination of IL-1β, IL-6, and transforming growth factor-β-neutralizing antibodies completely inhibited P. acnes-induced IL-17 production. Importantly, we showed that IL-17-expressing cells were present in skin biopsies from acne patients but not from normal donors. Finally, vitamin A (all-trans retinoic acid) and vitamin D (1,25-dihydroxyvitamin D3) inhibited P. acnes-induced Th17 differentiation. Together, our data demonstrate that IL-17 is induced by P. acnes and expressed in acne lesions and that both vitamin A and D could be effective tools to modulate Th17-mediated diseases such as acne

A compact and robust diode laser system for atom interferometry on a sounding rocket

We present a diode laser system optimized for laser cooling and atom interferometry with ultra-cold rubidium atoms aboard sounding rockets as an important milestone towards space-borne quantum sensors. Design, assembly and qualification of the system, combing micro-integrated distributed feedback (DFB) diode laser modules and free space optical bench technology is presented in the context of the MAIUS (Matter-wave Interferometry in Microgravity) mission. This laser system, with a volume of 21 liters and total mass of 27 kg, passed all qualification tests for operation on sounding rockets and is currently used in the integrated MAIUS flight system producing Bose-Einstein condensates and performing atom interferometry based on Bragg diffraction. The MAIUS payload is being prepared for launch in fall 2016. We further report on a reference laser system, comprising a rubidium stabilized DFB laser, which was operated successfully on the TEXUS 51 mission in April 2015. The system demonstrated a high level of technological maturity by remaining frequency stabilized throughout the mission including the rocket's boost phase