Atmospheric carbon dioxide and methane concentrations in the past and synchronisation of ice core records from both hemispheres based on methane results

In the central parts of the large polar ice sheets ice is formed by dry sintering of cold snow. The analyses of air extracted from bubbles of well dated ice samples from such locations, allow to determine the composition of the atmosphere at the time of ice formation. Of special interest are the two dominant greenhouse gases carbon dioxide and methane. The methane concentrations are very reproducible and represent the atmospheric concentration at the time of ice formation with a good accuracy. The records show unexpected variations of this concentration during the glacial epoch as well as during the Holocene. The concentration differences measured on ice cores from Greenland and Antarctica allow to determine concentration differences between the Northern and Southern Hemispheres. Ice core records show that the atmospheric CO_2 concentration has increased steadily from about 280 ppmv in 1750 to the present value of about 355 ppmv and that the large climatic change from the last glacial to the post glacial epoch was accompanied by a naturally caused increase of the atmospheric CO_2 concentration from about 200 ppmv to 280 ppmv. However, uncertainties about a possible CO_2 production in the ice make the investigation of smaller variations and accurate time lags between climatic changes and changes of the atmospheric CO_2 concentration especially in Greenland ice cores difficult. A synchronisation of ice core records from Greenland and Antarctica by methane results allows to compare CO_2 records from Antarctica with climatic records from Greenland

Intrapancreatic Accessory Spleen Misdiagnosed as a Nonsecreting Endocrine Tumor: Case Report and Review of the Literature

In a large series of nonselected autopsy investigations an accessory spleen was found in 10–30%. The second most common site is the pancreatic tail (17%). We report a case of intrapancreatic accessory spleen misdiagnosed as a nonsecreting neuroendocrine tumor of the pancreas. Nuclear scintigraphy may provide the definitive diagnosis of an intrapancreatic spleen and therefore prevent patients from unnecessary major surgery

Discussion of the reliability of CO2, CH4 and N2O records from polar ice cores (scientific paper)

Air in polar ice has about the same composition as atmospheric air at the time of ice formation. This allows to determine the composition, especially the concentration of greenhouse gases, in the past. However, the air composition in the ice can be slightly altered by chemical and biological processes in the ice. The reliability of long term trends can be determined by comparing records from different ice cores. For short duration details and time lags such comparisons are not possible due to uncertainties of the age scales of records from different cores. In this case very detailed records along sections of ice cores show whether the scatter of the results is larger than the theoretical expected one. A larger scatter is assumed to be caused by reactions between impurities in the ice which show generally short term variations. A low scatter of detailed high resolution records is therefore, a prerequisite for reliable records

Acromioclavicular joint cyst: nine cases of a pseudotumor of the shoulder

Objective: (1) To analyse the imaging appearances of nine patients with acromioclavicular joint cysts presenting as shoulder masses for tumor staging with operative, histopathological and joint aspiration findings. Design and patients: Retrospective review of imaging and correlation with clinical, operative and surgical notes. Images were reviewed by two musculoskeletal radiologists by consensus. Nine patients who presented clinically with a shoulder mass were evaluated by radiographs (n=9), ultrasound (n=1), conventional arthrography (n=3), MRI (n=6; with direct MR arthrography n=2, indirect MR arthrography n=4). Results: All patients had a focal mass superior to the AC joint, with a size ranging from 1.5cm to 6cm and a mean of 3.27cm. Correlation was available with surgery (n=7), histopathology (n=2) and cyst aspiration (n=2). Two patients were managed conservatively. Geyser sign was positive in all three arthrograms. All MRIs revealed extensive rotator cuff tears with a column of fluid extending from the glenohumeral joint through the rotator cuff tear into the acromioclavicular joint and acromioclavicular cyst. Chondrocalcinosis was seen in the acromioclavicular joint cyst (n=2) and in the glenohumeral joint (n=1). Aspirate in two patients contained calcium pyrophosphate dihydrate crystals. Conclusion: Acromioclavicular joint cysts may present as a tumor mass. They are associated with extensive rotator cuff tears and there is usually communication of the cyst with the joint space. This feature excludes a diagnosis of tumor. AC joint cysts may be associated with calcium pyrophosphate dihydrate deposition diseas

Localization in the quantum Hall regime

The localization properties of electron states in the quantum Hall regime are reviewed. The random Landau model, the random matrix model, the tight-binding Peierls model, and the network model of Chalker and Coddington are introduced. Descriptions in terms of equivalent tight-binding Hamiltonians, and the 2D Dirac model, are outlined. Evidences for the universal critical behavior of the localization length are summarized. A short review of the supersymmetric critical field theory is provided. The interplay between edge states and bulk localization properties is investigated. For a system with finite width and with short-range randomness, a sudden breakdown of the two-point conductance from $ne^{2}/h$ to 0 ($n$ integer) is predicted if the localization length exceeds the distance between the edges.Comment: 16 pages, to be published in Physica E, Proceedings of the Symposium "Quantum Hall Effect: Past, Present and Future

The Evolution of Invasiveness in Garden Ants

It is unclear why some species become successful invaders whilst others fail, and whether invasive success depends on pre-adaptations already present in the native range or on characters evolving de-novo after introduction. Ants are among the worst invasive pests, with Lasius neglectus and its rapid spread through Europe and Asia as the most recent example of a pest ant that may become a global problem. Here, we present the first integrated study on behavior, morphology, population genetics, chemical recognition and parasite load of L. neglectus and its non-invasive sister species L. turcicus. We find that L. neglectus expresses the same supercolonial syndrome as other invasive ants, a social system that is characterized by mating without dispersal and large networks of cooperating nests rather than smaller mutually hostile colonies. We conclude that the invasive success of L. neglectus relies on a combination of parasite-release following introduction and pre-adaptations in mating system, body-size, queen number and recognition efficiency that evolved long before introduction. Our results challenge the notion that supercolonial organization is an inevitable consequence of low genetic variation for chemical recognition cues in small invasive founder populations. We infer that low variation and limited volatility in cuticular hydrocarbon profiles already existed in the native range in combination with low dispersal and a highly viscous population structure. Human transport to relatively disturbed urban areas thus became the decisive factor to induce parasite release, a well established general promoter of invasiveness in non-social animals and plants, but understudied in invasive social insects

Mechanismen des Lufteinschlusses in natürlichem Eis

Natural ice is formed by freezing of water or by sintering of dry or wet snow. Each of these processes causes atmospheric air to be enclosed in ice as bubbles. The air amount and composition as well as the bubble sizes and density depend not only on the kind of process but also on several environmental conditions. The ice in the deepest layers of the Greenland and the Antarctic ice sheet was formed more than 100 000 years ago. In the bubbles of this ice, samples of atmospheric air from that time are preserved. The enclosure of air is discussed for each of the three processes. Of special interest are the parameters which control the amount and composition of the enclosed air. If the ice is formed by sintering of very cold dry snow, the air composition in the bubbles corresponds with good accuracy to the composition of atmospheric air

Die Zusammensetzung der Luft in natürlichem Eis

The air trapped in freshly formed ice gives information concerning the ice formation processes as well as concerning several environmental parameters at the time of ice formation. Air amount, air composition, and the size and form of bubbles may change with time. Possible processes responsible for such changes are discussed. In very cold ice air content and air composition remain almost unchanged. Samples of ancient atmospheric air are therefore very well preserved in cold ice. In temperate ice changes of the air amount and air composition depend on the intergranular water flow through the glacier. This waterflow can be estimated by measuring air amount and air composition in ice samples