Mechanismen und Vorhersagbarkeit des nordatlantisch-europäischen Klimas

This study investigates the mechanisms of North Atlantic-European climate using atmosphere general circulation models (AGCMs). Experiments with the AGCM ECHAM4, in which the sea surface temperature (SST) forcing is restricted to either the Atlantic or the Indo-Pacific oceans, show that both oceanic regions have an influence on North Atlantic-European climate in winter. In the experiment with SST forcing restricted to the Indo-Pacific oceans the atmospheric response projects on the North Atlantic Oscillation (NAO), while in the experiment with SST forcing restricted to the Atlantic Ocean the atmospheric response projects on the East-Atlantic Pattern. A multi-model intercomparison study shows that the region with the dominant influence on North Atlantic-European winter climate varies between different AGCMs. The dominant forcing of the atmospheric variability in the North Atlantic-European region in ECHAM4 is from the tropical eastern Pacific. However, in three other AGCMs the dominant forcing of this mode is from the tropical North Atlantic region. The importance of North Atlantic SST for North Atlantic-European climate is shown in another multi-model intercomparison study. The idealized North Atlantic SST anomaly pattern for this experiment has the structure of a tripole, which is believed to have the strongest impact on North Atlantic climate. Agreements between the responses in the different AGCMs are found concerning the NAO, Eurasian temperatures, rainfall over America and Africa, and the Asian monsoon. The results suggest that the extratropical North Atlantic region response is associated with remote Caribbean and tropical Atlantic SST anomalies, and with local forcing. All of these results support the conclusion that the ocean has a significant influence on North Atlantic-European climate. In addition to the mechanisms, this study investigates the predictability of North Atlantic-European climate. A control integration and ensemble experiments with the coupled atmosphere-ocean general circulation model (AOGCM) ECHAM5/MPI-OM are analyzed to investigate the decadal climate predictability. The ensemble experiments are realized with slightly perturbed atmospheric but the same oceanic initial conditions. The results show that the North Atlantic thermohaline circulation (THC) and SST are potentially predictable on multidecadal timescales. Over the ocean the predictability of surface air temperature (SAT) is very similar to that of SST, and this signal proceeds into the lower troposphere. Over land there is little evidence of decadal predictability of SAT with classical predictability methods. However, the estimation of the potential predictability over the European continent with probabilistic methods, commonly used in seasonal and medium-range forecasting, exhibits some limited success on decadal timescales. A multi-model comparison study with five AOGCMs confirms the potential predictability of North Atlantic THC and SST, albeit with skill levels dependent on the AOGCM. In general, models with greater decadal THC variability have higher levels of potential predictability

Discontinuities in the late 1960's in different atmospheric data products

An analysis of the onset and spatial extent of discontinuities in the late 1960's in different atmospheric data products is performed. Discontinuities are found in both the NCEP/NCAR and ERA-40 reanalyses in various surface variables including sea level pressure (SLP) in both data sets over Africa, in the NCEP/NCAR reanalysis also over Asia and in the ERA-40 reanalysis also over South America, and precipitation in the NCEP/NCAR reanalysis over North Africa. Discontinuities are also found in 2 m air temperature in both reanalyses. The discontinuities in SLP extend into the lower troposphere. The main cause of these discontinuities appears to be missing or limited synoptic data prior to the late 1960's

Atlantic versus Indo-Pacific influence on Atlantic-European climate

The influence of the Atlantic and Indo-Pacific oceans on Atlantic-European climate is investigated by analyzing ensemble integrations with the atmospheric general circulation model ECHAM4 forced by anomalous sea surface temperature and sea ice conditions restricted to the Atlantic (AOGA) and Indo-Pacific (I+POGA) oceans. The forcing from both the Indo-Pacific and Atlantic oceans are important for the generation of the sea level pressure (SLP) variability in the Atlantic region in the boreal winter season. Over the North Atlantic the SLP response in the I+POGA experiment projects on the North Atlantic Oscillation, while it projects on the East Atlantic Pattern in the AOGA experiment. In both experiments (I+POGA and AOGA) a quadrupole-type 500 hPa height anomaly pattern is simulated which emerges from the tropical Pacific and Atlantic oceans, respectively. In boreal summer the influence of the Atlantic Ocean dominates the SLP response in the Atlantic region. The tropical North Atlantic is a key region in forcing the SLP response over the Caribbean Sea in this season

Advanced head and neck cancer: Long-term results of chemo-radiotherapy, complications and induction of second malignancies

Background: Chemo-radiotherapy is superior to radiotherapy alone in the treatment of advanced, inoperable head and neck cancer. The long-term treatment results, the induction of second malignant tumors, and other long-term toxicities are not well defined. Patients and Methods: 100 consecutive patients with advanced head and neck cancer who were treated at our center were studied. Treatment results, survival, the occurrence of late complications, and second malignant tumors (SMT) were investigated. 78 patients were treated with a protocol combining cisplatinum, 5-fluorouracil, folinic acid and hyper-fractionated irradiation. 22 patients were treated with other chemo-radiotherapy protocols. The relative risk of developing an SMT was compared with that within the normal population. Results: The cumulative total probability of survival was 51.1% at 2 years and 38.7% at 4 years. The probability of relapse-free survival was 39.9% at 2 years and 36.7% at 4 years. A total of 7 patients developed SMT (4 cases of lung cancer, 2 colon cancers, 1 skin cancer). After 6 years, a cumulative risk of SMT of 8.7% was observed. The relative risk of developing an SMT was significantly increased (4.45-fold in males) compared with a normal population. 13 of 38 evaluable patients (34.2%) had severe late complications like fibrosis of soft tissues, nerve lesions, or were dependent on tracheal cannulas. Conclusions: The treatment results and long-term prognoses in our population of unselected high-risk patients are unsatisfactory, but comparable to those from multicenter studies. About 35% of patients become long-term (> 4 years) survivors. SMT generally occur early, have a poor prognosis and, most likely, are not treatment-related. Approximately 30% of long-term survivors have severe, often incapacitating late effects. The treatment and - if possible - prevention of these late effects is important for the quality of life of patients who survived advanced head and neck cancer

Spontaneous bleeding in a patient with malignant lymphoma: A case of acquired hemophilia

Background: Acquired hemophilia is a rare condition which can be associated with lymphoproliferative disease. Case Report: Eleven yea rs after the diagnosis of immunocytoma had been made, a 72-year-old man developed a high-titer factor VIII inhibitor. At this time, the lymphoma was without significant progress and there was no paraprotein in the serum. Partial thromboplastin time (PTT) was 83 a, factor-VIII clotting activity was <1%, and inhibitor level was 50.4 Bethesda units. The patient presented with spontaneous hematomas in the skin and musculature of the extremities. Following combination chemotherapy with cyclophosphamide, vincristine and prednisolone (COP), there was a prompt disappearance of the inhibitor and normalization of coagulation; however, the patient developed serious infectious complications. When the inhibitor recurred he was treated with low-dose cyclophosphamide and prednisolone. This time there was a more delayed response, but the inhibitor disappeared again completely. Two months after cessation of therapy, there was again relapse. Conclusion: Causal relationship between lymphoma and acquired hemophilia remains speculative. At least in some cases of factor VIII inhibitors associated with malignant disease, immunosuppressive therapy may be sufficient to suppress the inhibitor

Expression of DC-SIGN and DC-SIGNR on human sinusoidal endothelium: a role for capturing hepatitis C virus particles.

Hepatic sinusoidal endothelial cells are unique among endothelial cells in their ability to internalize and process a diverse range of antigens. DC-SIGNR, a type 2 C-type lectin expressed on liver sinusoids, has been shown to bind with high affinity to hepatitis C virus (HCV) E2 glycoprotein. DC-SIGN is a closely related homologue reported to be expressed only on dendritic cells and a subset of macrophages and has similar binding affinity to HCV E2 glycoprotein. These receptors function as adhesion and antigen presentation molecules. We report distinct patterns of DC-SIGNR and DC-SIGN expression in human liver tissue and show for the first time that both C-type lectins are expressed on sinusoidal endothelial cells. We confirmed that these receptors are functional by demonstrating their ability to bind HCV E2 glycoproteins. Although these lectins on primary sinusoidal cells support HCV E2 binding, they are unable to support HCV entry. These data support a model where DC-SIGN and DC-SIGNR on sinusoidal endothelium provide a mechanism for high affinity binding of circulating HCV within the liver sinusoids allowing subsequent transfer of the virus to underlying hepatocytes, in a manner analogous to DC-SIGN presentation of human immunodeficiency virus on dendritic cells

Initializing decadal climate predictions with the GECCO oceanic synthesis

This study aims at improving the forecast skill of climate predictions through the use of ocean synthesis data for initial conditions of a coupled climate model. For this purpose, the coupled model of the Max Planck Institute (MPI) for Meteorology, which consists of the atmosphere model ECHAM5 and the MPI Ocean Model (MPI-OM), is initialized with oceanic synthesis fields available from the German contribution to Estimating the Circulation and Climate of the Ocean (GECCO) project. The use of an anomaly coupling scheme during the initialization avoids the main problems with drift in the climate predictions. Thus, the coupled model is continuously forced to follow the density anomalies of the GECCO synthesis over the period 1952-2001. Hindcast experiments are initialized from this experiment at constant intervals. The results show predictive skill through the initialization up to the decadal time scale, particularly over the North Atlantic. Viewed over the time scales analyzed here (annual, 5-yr, and 10-yr mean), greater skill for the North Atlantic sea surface temperature (SST) is obtained in the hindcast experiments than in either a damped persistence or trend forecast. The Atlantic meridional overturning circulation hindcast closely follows that of the GECCO oceanic synthesis. Hindcasts of global-mean temperature do not obtain greater skill than either damped persistence or a trend forecast, owing to the SST errors in the GECCO synthesis, outside the North Atlantic. An ensemble of forecast experiments is subsequently performed over the period 2002-11. North Atlantic SST from the forecast experiment agrees well with observations until the year 2007, and it is higher than if simulated without the oceanic initialization (averaged over the forecast period). The results confirm that both the initial and the boundary conditions must be accounted for in decadal climate predictions