Collisional decay of 87Rb Feshbach molecules at 1005.8 G

We present measurements of the loss-rate coefficients K_am and K_mm caused by inelastic atom-molecule and molecule-molecule collisions. A thermal cloud of atomic 87Rb is prepared in an optical dipole trap. A magnetic field is ramped across the Feshbach resonance at 1007.4 G. This associates atom pairs to molecules. A measurement of the molecule loss at 1005.8 G yields K_am=2 10^-10 cm^3/s. Additionally, the atoms can be removed with blast light. In this case, the measured molecule loss yields K_mm=3 10^-10 cm^3/s

Attosecond Streaking in the Water Window: A New Regime of Attosecond Pulse Characterization

We report on the first streaking measurement of water-window attosecond pulses generated via high harmonic generation, driven by sub-2-cycle, CEP-stable, 1850 nm laser pulses. Both the central photon energy and the energy bandwidth far exceed what has been demonstrated thus far, warranting the investigation of the attosecond streaking technique for the soft X-ray regime and the limits of the FROGCRAB retrieval algorithm under such conditions. We also discuss the problem of attochirp compensation and issues regarding much lower photo-ionization cross sections compared with the XUV in addition to the fact that several shells of target gases are accessed simultaneously. Based on our investigation, we caution that the vastly different conditions in the soft X-ray regime warrant a diligent examination of the fidelity of the measurement and the retrieval procedure.Comment: 14 Pages, 12 figure

A high-resolution 43-year atmospheric hindcast for South America generated with the MPI regional model

An evaluation of the present-day climate in South America simulated by the MPI atmospheric limited area model, REMO, is made. The model dataset was generated by dynamical downscaling from the ECMWF-ERA40 reanalysis and compared to in-situ observations. The model is able to reproduce the low-level summer monsoon circulation but it has some deficiencies in representing the South American Low-Level Jet structure. At upper levels, summer circulation features like the Bolivian High and the associated subtropical jet are well simulated by the model. Sea-level pressure fields are in general well represented by REMO. The model exhibits reasonable skill in representing the general features of the mean seasonal cycle of precipitation. Nevertheless, there is a systematic overestimation of precipitation in both tropical and subtropical regions. Differences between observed and modeled temperature are smaller than 1.5A degrees C over most of the continent, excepting during spring when those differences are quite large. Results also show that the dynamical downscaling performed using REMO introduces some enhancement of the global reanalysis especially in temperature at the tropical regions during the warm season and in precipitation in both the subtropics and extratropics. It is then concluded that REMO can be a useful tool for regional downscaling of global simulations of present and future climates

Bose-Einstein condensates in a double well: mean-field chaos and multi-particle entanglement

A recent publication [Phys. Rev. Lett. 100, 140408 (2008)] shows that there is a relation between mean-field chaos and multi-particle entanglement for BECs in a periodically shaken double well. 'Schrodinger-cat' like mesoscopic superpositions in phase-space occur for conditions for which the system displays mean-field chaos. In the present manuscript, more general highly-entangled states are investigated. Mean-field chaos accelerates the emergence of multi-particle entanglement; the boundaries of stable regions are particularly suited for entanglement generation.Comment: 5 Pages, 5 jpg-figures, to be published in the proceedings of the LPHYS0

Single-cell analysis of human B cell maturation predicts how antibody class switching shapes selection dynamics.

Protective humoral memory forms in secondary lymphoid organs where B cells undergo affinity maturation and differentiation into memory or plasma cells. Here, we provide a comprehensive roadmap of human B cell maturation with single-cell transcriptomics matched with bulk and single-cell antibody repertoires to define gene expression, antibody repertoires, and clonal sharing of B cell states at single-cell resolution, including memory B cell heterogeneity that reflects diverse functional and signaling states. We reconstruct gene expression dynamics during B cell activation to reveal a pre-germinal center state primed to undergo class switch recombination and dissect how antibody class-dependent gene expression in germinal center and memory B cells is linked with a distinct transcriptional wiring with potential to influence their fate and function. Our analyses reveal the dynamic cellular states that shape human B cell-mediated immunity and highlight how antibody isotype may play a role during their antibody-based selection. This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science Immunology on Science Immunology Vol. 6, Feb 2021, DOI: 10.1126/sciimmunol.abe6291

Strong coupling expansion for the Bose-Hubbard and the Jaynes-Cummings lattice model

A strong coupling expansion, based on the Kato-Bloch perturbation theory, which has recently been proposed by Eckardt et al. [Phys. Rev. B 79, 195131] and Teichmann et al. [Phys. Rev. B 79, 224515] is implemented in order to study various aspects of the Bose-Hubbard and the Jaynes-Cummings lattice model. The approach, which allows to generate numerically all diagrams up to a desired order in the interaction strength is generalized for disordered systems and for the Jaynes-Cummings lattice model. Results for the Bose-Hubbard and the Jaynes-Cummings lattice model will be presented and compared with results from VCA and DMRG. Our focus will be on the Mott insulator to superfluid transition.Comment: 29 pages, 21 figure

Projektabwicklung und Ergebnisse des Bund-Länder-1000-Dächer-Photovoltaik-Programmes in Sachsen

Im Report werden die im Rahmen des Bund-Länder-1000-Dächer-Photovoltaik-Programmes in Sachsen erzielten Ergebnisse dargestellt. Insgesamt wurden auf Dächern von Ein- und Zweifamilienhäusern in den Jahren 1992 - 1994 150 netzgekoppelte Anlagen mit einer Gesamtleistung von 523 kWp errichtet. Dabei kamen Module und Wechselrichter von jeweils acht verschiedenen europäischen Herstellern zum Einsatz. Die beteiligten Fachfirmen erwarben ein breites Know-how zur Auslegung und Installation der Anlagen sowie zur architektonischen und bautechnischen Einbindung der Photovoltaikgeneratoren auf Dächern von Einfamilienhäusern. Entsprechende Ergebnisse werden zusammenfassend vorgestellt. Die Ergebnisse des begleitenden Meßprogrammes werden im Detail diskutiert. Erstmals werden quantitative Zusammenhänge zwischen der solaren Energieproduktion und dem Eigenbedarf von Haushalten ermittelt. Der jährliche Elektroenergiebedarf von Haushalten kann durch dachmontierte PV-Anlagen unter mitteleuropäischen Bedingungen voll gedeckt werden. Die mögliche jährliche Energieproduktion einer Photovoltaikanlage in Sachsen beträgt 750 kWh/kWp, die weitere Minimierung der anlagenbedingten Verluste ist Gegenstand weiterführender Untersuchungen

RNA sequencing reveals two major classes of gene expression levels in metazoan cells

The expression level of a gene is often used as a proxy for determining whether the protein or RNA product is functional in a cell or tissue. Therefore, it is of fundamental importance to understand the global distribution of gene expression levels, and to be able to interpret it mechanistically and functionally. Here we use RNA sequencing of mouse Th2 cells, coupled with a range of other techniques, to show that all genes can be separated, based on their expression abundance, into two distinct groups: one group comprising of lowly expressed and putatively non-functional mRNAs, and the other of highly expressed mRNAs with active chromatin marks at their promoters

Case study for the assessment of the biogeophysical effects of a potential afforestation in Europe

BACKGROUND: A regional-scale sensitivity study has been carried out to investigate the climatic effects of forest cover change in Europe. Applying REMO (regional climate model of the Max Planck Institute for Meteorology), the projected temperature and precipitation tendencies have been analysed for summer, based on the results of the A2 IPCC-SRES emission scenario simulation. For the end of the 21st century it has been studied, whether the assumed forest cover increase could reduce the effects of the greenhouse gas concentration change. RESULTS: Based on the simulation results, biogeophysical effects of the hypothetic potential afforestation may lead to cooler and moister conditions during summer in most parts of the temperate zone. The largest relative effects of forest cover increase can be expected in northern Germany, Poland and Ukraine, which is 15-20% of the climate change signal for temperature and more than 50% for precipitation. In northern Germany and France, potential afforestation may enhance the effects of emission change, resulting in more severe heavy precipitation events. The probability of dry days and warm temperature extremes would decrease. CONCLUSIONS: Large contiguous forest blocks can have distinctive biogeophysical effect on the climate on regional and local scale. In certain regions of the temperate zone, climate change signal due to greenhouse gas emission can be reduced by afforestation due to the dominant evaporative cooling effect during summer. Results of this case study with a hypothetical land cover change can contribute to the assessment of the role of forests in adapting to climate change. Thus they can build an important basis of the future forest policy