Atmospheric Response to Ice-Age Conditions - Climatology near the Earth's Surface

We present a 6-year simulation of the ice age atmosphere using the T21 Atmospheric General Circulation Model (AGCM) of the European Centre for Medium-Range Weather Forecasts (ECMWF). The lower boundary conditions (18 kyr B.P.) were taken from CLIMAP Project Members (1981). The analysis is restricted to the surface climatology for two reasons: The surface fields are the test data derived from the geological record on land, and they define the upper boundary conditions for simulating the glacial ocean. Model results are shown for the mean annual surface fields of temperature, wind, and precipitation. In the global average the surface temperature was 4.7øC cooler compared to the present temperature. The wind strength increased in mid-latitudes and decreased in tropical trade wind regions. Precipitation did not change significantly in the global average; however, precipitation decreased over land and increased over the ocean. Most of the difference patterns between the present conditions and the ice age climate were statistically significant. The simulated surface climatology is roughly consistent with the paleogeological evidence and with numerical AGCM simulations of other authors. This suggests that presently available AGCMs, including the ECMWF model (T21), are able to describe climates far away from the present, although internal parameteriza- tions were tuned to present data sets

Temperature suppression of STM-induced desorption of hydrogen on Si(100) surfaces

The temperature dependence of hydrogen (H) desorption from Si(100) H-terminated surfaces by a scanning tunneling microscope (STM) is reported for negative sample bias. It is found that the STM induced H desorption rate ($R$) decreases several orders of magnitude when the substrate temperature is increased from 300 K to 610 K. This is most noticeable at a bias voltage of -7 V where $R$ decreases by a factor of ~200 for a temperature change of 80 K, whilst it only decreases by a factor of ~3 at -5 V upon the same temperature change. The experimental data can be explained by desorption due to vibrational heating by inelastic scattering via a hole resonance. This theory predicts a weak suppression of desorption with increasing temperature due to a decreasing vibrational lifetime, and a strong bias dependent suppression due to a temperature dependent lifetime of the hole resonance.Comment: 5 pages, RevTeX, epsf files. Accepted for surface science letter

Inverse energy cascade in three-dimensional isotropic turbulence

In turbulent flows kinetic energy is spread by nonlinear interactions over a broad range of scales. Energy transfer may proceed either toward small scales or in the reverse direction. The latter case is peculiar of two-dimensional (2D) flows. Interestingly, a reversal of the energy flux is observed also in three-dimensional (3D) geophysical flows under rotation and/or confined in thin layers. The question is whether this phenomenon is enforced solely by external anisotropic mechanisms or it is intimately embedded in the Navier-Stokes (NS) equations. Here we show that an inverse energy cascade occurs also in 3D isotropic flow. The flow is obtained from a suitable surgery of the NS equations, keeping only triadic interactions between sign-defined helical modes, preserving homogeneity and isotropy and breaking reflection invariance. Our findings highlight the role played by helicity in the energy transfer process and show that both 2D and 3D properties naturally coexist in all flows in nature.Comment: 4 pages, 4 figure

FAIR Practices in Europe

Institutions driving fundamental research at the cutting edge such as for example from the Max Planck Society (MPS) took steps to optimize data management and stewardship to be able to address new scientific questions. In this paper we selected three institutes from the MPS from the areas of humanities, environmental sciences and natural sciences as examples to indicate the efforts to integrate large amounts of data from collaborators worldwide to create a data space that is ready to be exploited to get new insights based on data intensive science methods. For this integration the typical challenges of fragmentation, bad quality and also social differences had to be overcome. In all three cases, well-managed repositories that are driven by the scientific needs and harmonization principles that have been agreed upon in the community were the core pillars. It is not surprising that these principles are very much aligned with what have now become the FAIR principles. The FAIR principles confirm the correctness of earlier decisions and their clear formulation identified the gaps which the projects need to address

HHV-6 in liver transplantation : A literature review

Human herpesvirus 6 (HHV-6A and HHV-6B) can cause primary infection or reactivate from latency in liver transplant recipients, which can result in a variety of clinical syndromes, including fever, hepatitis, encephalitis and higher rates of graft dysfunction as well as indirect effects including increased risks of mortality, CMV disease, hepatitis C progression and greater fibrosis scores. Although HHV-6 infection is currently diagnosed by quantifying viral DNA in plasma or blood, biopsy to demonstrate histopathological effects of HHV-6 remains the gold standard for diagnosis of end-organ disease. HHV-6 reactivation may be restricted to the infected organ with no evidence of active infection in the blood. HHV-6 infections in liver transplant patients are mostly asymptomatic, but clinically significant tissue-invasive infections have been treated successfully with ganciclovir, foscarnet or cidofovir. Inherited chromosomally integrated HHV-6 (ciHHV-6), in either the recipient or the donor organ, may create confusion about systemic HHV-6 infection. Recipients with inherited ciHHV-6 may have an increased risk of opportunistic infection and graft rejection. This article reviews the current scientific data on the clinical effects, risk factors, pathogenesis, diagnosis and treatment of HHV-6 infections in liver transplant recipients.Peer reviewe

17-jähriger Mann mit akuten Bauchschmerzen, Hämatochezie und Exanthem

Zusammenfassung: Ein 17-jähriger Patient stellte sich mit kolikartigen abdominellen Schmerzen und Diarrhö vor. Als weitere Symptome traten Petechien, Arthralgien und eine Hämatochezie auf. Sonographisch bestand eine auffällige Ileozökalregion. Endoskopisch fand sich eine Ileitis terminalis, und histologisch zeigte sich hier eine leukozytoklastische Vaskulitis mit IgA-Ablagerungen. Die Kasuistik zeigt exemplarisch die mehrzeitige klinische Manifestation der Purpura Schönlein-Henoch und deren Verlau

Rare human skin infection with Corynebacterium ulcerans: transmission by a domestic cat

Corynebacterium ulcerans is mainly known for its ability to cause animal infections. Some strains of C. ulcerans produce diphtheria toxin, which can cause life-threatening cardiopathies and neuropathies in humans. Human cutaneous C. ulcerans infection is a very rare disease that mimics classical cutaneous diphtheria. We present a very rare case of a C. ulcerans skin infection caused by a non-diphtheria toxin-producing strain of C. ulcerans that resolved after 3weeks of therapy with amoxicillin-clavulanate. A pet cat was the probable source of infection. The presence of C. ulcerans in the mouth of the cat was confirmed by 16S rRNA gene analysis and the API Coryne system. In cases of human infection with potentially toxigenic corynebacteria, it is important to determine the species and examine the isolate for diphtheria toxin production. If toxigenicity is present, diphtheria antitoxin should be administered immediately. Carriers and potential infectious sources of C. ulcerans include not only domestic livestock but also pet animals. For the primary prevention of disease caused by diphtheria toxin-producing corynebacteria, vaccination with diphtheria toxoid is recommende