High-Precision Spectroscopy with Counter-Propagating Femtosecond Pulses

An experimental realization of high-precision direct frequency comb spectroscopy using counter-propagating femtosecond pulses on two-photon atomic transitions is presented. Doppler broadened background signal, hampering precision spectroscopy with ultrashort pulses, is effectively eliminated with a simple pulse shaping method. As a result, all four 5S-7S two-photon transitions in a rubidium vapor are determined with both statistical and systematic uncertainties below 10$^{-11}$, which is an order of magnitude better than previous experiments on these transitions.Comment: 5 pages, 4 figures. Accepted to PR

Concept for the measurement of vital parameters during the use of an infrared cabin to investigate physiological effects and to individualize the sauna session

Infrared sauna bathing has positive effects on body and mind. Quantifying these effects helps to make sauna use more efficient and safer and to increase the user-observed wellness effects. Currently, there are no practical solutions for a comprehensive and user-friendly monitoring of the physical impact of sauna bathing. This paper focuses on the concept development to investigate which measurement setups are suitable to record and evaluate changes in vital parameters. Based on prioritized vital parameters and requirements a pre-selection of devices in form of wearables is made, which is going to be examined in detail for their suitability. An investigation with ten test persons is planned, in which the wearables’ measurement accuracy and the user acceptance outside and inside the infrared cabin are quantified. The result is a concept for the test procedure and the evaluation of the wearables in order to integrate a suitable device into the overall system

Precision CMB constraints on eV-scale bosons coupled to neutrinos

The cosmic microwave background (CMB) has proven to be an invaluable tool for studying the properties and interactions of neutrinos, providing insight not only into the sum of neutrino masses but also the free streaming nature of neutrinos prior to recombination. The CMB is a particularly powerful probe of new eV-scale bosons interacting with neutrinos, as these particles can thermalize with neutrinos via the inverse decay process, $\nu\bar{\nu} \rightarrow X$, and suppress neutrino free streaming near recombination -- even for couplings as small as $\lambda_\nu \sim \mathcal{O}(10^{-13})$. Here, we revisit CMB constraints on such bosons, improving upon a number of approximations previously adopted in the literature and generalizing the constraints to a broader class of models. This includes scenarios in which the boson is either spin-$0$ or spin-$1$, the number of interacting neutrinos is either $N_{\rm int} = 1,2$ or $3$, and the case in which a primordial abundance of the species is present. We apply these bounds to well-motivated models, such as the singlet majoron model or a light $U(1)_{L_\mu-L_\tau}$ gauge boson, and find that they represent the leading constraints for masses $m_X\sim 1\, {\rm eV}$. Finally, we revisit the extent to which neutrino-philic bosons can ameliorate the Hubble tension, and find that recent improvements in the understanding of how such bosons damp neutrino free streaming reduces the previously found success of this proposal.Comment: 9 + 8 pages, 14 figures, added minor comment on Hubble tension, matches published versio

Spatial coherence control and analysis via micromirror-based mixed-state ptychography

Flexible and fast control of the phase and amplitude of coherent light, enabled by digital micromirror devices (DMDs) and spatial light modulators (SLMs), has been a driving force for recent advances in optical tweezers, nonlinear microscopy, and wavefront shaping. In contrast, engineering spatially partially coherent light remains widely elusive due to the lack of tools enabling a joint analysis and control sequence. Here, we report an approach to coherence engineering that combines a quasi-monochromatic, thermal source and a DMD together with a ptychographic scanning microscope. The reported method opens up new routes to low-cost coherence control, with applications in micromanipulation, nanophotonics, and quantitative phase contrast imaging

Acquisition of chemical recognition cues facilitates integration into ant societies

<p>Abstract</p> <p>Background</p> <p>Social insects maintain the integrity of their societies by discriminating between colony members and foreigners through cuticular hydrocarbon (CHC) signatures. Nevertheless, parasites frequently get access to social resources, for example through mimicry of host CHCs among other mechanisms. The origin of mimetic compounds, however, remains unknown in the majority of studies (biosynthesis vs. acquisition). Additionally, direct evidence is scarce that chemical mimicry is indeed beneficial to the parasites (e.g., by improving social acceptance).</p> <p>Results</p> <p>In the present study we demonstrated that the kleptoparasitic silverfish <it>Malayatelura ponerophila </it>most likely acquires CHCs directly from its host ant <it>Leptogenys distinguenda </it>by evaluating the transfer of a stable-isotope label from the cuticle of workers to the silverfish. In a second experiment, we prevented CHC pilfering by separating silverfish from their host for six or nine days. Chemical host resemblance as well as aggressive rejection behaviour by host ants was then quantified for unmanipulated and previously separated individuals. Separated individuals showed reduced chemical host resemblance and they received significantly more aggressive rejection behaviour than unmanipulated individuals.</p> <p>Conclusion</p> <p>Our study clarifies the mechanism of chemical mimicry in a social insect parasite in great detail. It shows empirically for the first time that social insect parasites are able to acquire CHCs from their host. Furthermore, it demonstrates that the accuracy of chemical mimicry can be crucial for social insect parasites by enhancing social acceptance and, thus, allowing successful exploitation. We discuss the results in the light of coevolutionary arms races between parasites and hosts.</p

High-density P300 enhancers control cell state transitions.

BACKGROUND: Transcriptional enhancers are frequently bound by a set of transcription factors that collaborate to activate lineage-specific gene expression. Recently, it was appreciated that a subset of enhancers comprise extended clusters dubbed stretch- or super-enhancers (SEs). These SEs are located near key cell identity genes, and enriched for non-coding genetic variations associated with disease. Previously, SEs have been defined as having the highest density of Med1, Brd4 or H3K27ac by ChIP-seq. The histone acetyltransferase P300 has been used as a marker of enhancers, but little is known about its binding to SEs. RESULTS: We establish that P300 marks a similar SE repertoire in embryonic stem cells as previously reported using Med1 and H3K27ac. We also exemplify a role for SEs in mouse T helper cell fate decision. Similarly, upon activation of macrophages by bacterial endotoxin, we found that many SE-associated genes encode inflammatory proteins that are strongly up-regulated. These SEs arise from small, low-density enhancers in unstimulated macrophages. We also identified expression quantitative trait loci (eQTL) in human monocytes that lie within such SEs. In macrophages and Th17 cells, inflammatory SEs can be perturbed either genetically or pharmacologically thus revealing new avenues to target inflammation. CONCLUSIONS: Our findings support the notion that P300-marked SEs can help identify key nodes of transcriptional control during cell fate decisions. The SE landscape changes drastically during cell differentiation and cell activation. As these processes are crucial in immune responses, SEs may be useful in revealing novel targets for treating inflammatory diseases

Acoustic Stimuli Can Improve and Impair Somatosensory Perception

The integration of stimuli from different sensory modalities forms the basis for human perception. While the relevant impact of visual stimuli on the perception of other sensory modalities is recognized, much less is known about the impact of auditory stimuli on general sensory processing. This study aims to investigate the effect of acoustic stimuli on the processing of somatosensory stimuli using real noise (i.e., unpleasant everyday noise, RN) and neutral white noise ( WN ). To this purpose, we studied 20 healthy human subjects between 20 and 29 years of age (mean: 24, SD: ±1.9 years sex ratio 1:1). Somatosensory perception was evaluated using mechanical detection threshold (MDT) of the skin on the back of the dominant hand. To investigate the underlying mechanisms in the brain, fMRI was performed while applying acoustic stimulation (RN and WN) and tactile stimulation of the dominant hand. Here we show that acoustic stimulation with noise alters the perception of touch on the skin. We found that the effect of RN and WN differed. RN leads to an improved tactile perception, whereas WN impaired tactile perception. These changes go along with significant differences in brain activity and connectivity. WN is associated with a significant increase in brain activity in multiple brain areas such as the auditory and somatosensory cortex, parietal association cortex, and the thalamus compared to RN . With tactile stimulation of the skin, the flow of information in these brain areas is altered. While with RN the information flow from the thalamus to the somatosensory cortex is prominent, the network activity pattern changes under WN revealing an increase in interaction between multiple networks. Unpleasant noise inhibits the multisensory integration and enables a more efficient unimodal perception in the somatosensory system, improving perception. Whether this is to be interpreted as a temporary increase in phasic alertness or by a stronger filter function of the thalamus with a preference for unimodal stimuli is still open for debate

TAS - touristisches Assistenzsystem für Urlaub, Freizeit- und Bildungsaktivitäten - ein InnoRegio-Projekt der TU Ilmenau

Um den gesellschaftlichen Anspruch der gleichberechtigten Teilhabe behinderter Menschen auch im touristischen Umfeld zu gewährleisten, wurde im Rahmen eines BMBF-geförderten Verbundprojektes ein Touristisches Assistenzsystem entwickelt. Die Basis dieses Systems sind individuell anpassbare moderne IT-Komponenten, die über verschiedene Kommunikationskanäle in permanenter Verbindung zu einer Datenbasis auf einem Serversystem stehen. Darauf sind notwendige Informationen über den Nutzer und die Region einschließlich vorhandener Bewegungshindernisse abgelegt. Für jeden Systemnutzer werden anhand seiner Anforderungen individuelle schaffbare Routen geplant und bei Veränderung der Situation auch aktualisiert und umgeplant. Das Serversystem ist als Leitstelle auch mit Leistungsanbietern verbunden, die eine schnelle und effektive Hilfe für die Betroffenen bei Notwendigkeit leisten können

Recent development in adsorption materials and heat exchangers for thermally driven heat pumps

Part of: Thermally driven heat pumps for heating and cooling. – Ed.: Annett Kühn – Berlin: Universitätsverlag der TU Berlin, 2013 ISBN 978-3-7983-2686-6 (print) ISBN 978-3-7983-2596-8 (online) urn:nbn:de:kobv:83-opus4-39458 [http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-39458]Adsorption chillers and heat pumps are a promising technology for the supply of heating and cooling, especially in the small scale range. Therefore, adsorption materials with a high load capacity and heat exchangers with effective heat and mass transfer ratios are required. To compare the characteristics of adsorption-refrigerant working pairs from different manufacturers a common measurement method is required. This paper gives a literature survey about the state of the art in adsorption material developments and proposes a common measurement procedure for adsorbents. Moreover the latest activities in heat exchanger developments for adsorption heat exchangers and evaporators are represented