Coulomb crystallization of highly charged ions.

Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.

Collisional stability of a three-component degenerate fermi gas.

We report on the creation of a degenerate Fermi gas consisting of a balanced mixture of atoms in three different hyperfine states of 6Li. This new system consists of three distinguishable fermions with different and tunable interparticle scattering lengths a_{12}, a_{13}, and a_{23}. We are able to prepare samples containing 5x10;{4} atoms in each state at a temperature of about 215 nK, which corresponds to T/T_{F} approximately 0.37. We investigated the collisional stability of the gas for magnetic fields between 0 and 600 G and found a prominent loss feature at 130 G. From lifetime measurements, we determined three-body loss coefficients, which vary over nearly 3 orders of magnitude.

Content-based image retrieval in medical applications.

OBJECTIVES: To develop a general structure for semantic image analysis that is suitable for content-based image retrieval in medical applications and an architecture for its efficient implementation. METHODS: Stepwise content analysis of medical images results in six layers of information modeling incorporating medical expert knowledge (raw data layer, registered data layer, feature layer, scheme layer, object layer, knowledge layer). A reference database with 10,000 images categorized according to the image modality, orientation, body region, and biological system is used. By means of prototypes in each category, identification of objects and their geometrical or temporal relationships are handled in the object and the knowledge layer, respectively. A distributed system designed with only three core elements is implemented: (i) the central database holds program sources, processing scheme descriptions, images, features, and administrative information about the workstation cluster; (ii) the scheduler balances distributed computing; and (iii) the web server provides graphical user interfaces for data entry and retrieval, which can be easily adapted to a variety of applications for content-based image retrieval in medicine. RESULTS: Leaving-one-out experiments were distributed by the scheduler and controlled via corresponding job lists offering transparency regarding the viewpoints of a distributed system and the user. The proposed architecture is suitable for content-based image retrieval in medical applications. It improves current picture archiving and communication systems that still rely on alphanumerical descriptions, which are insufficient for image retrieval of high recall and precision.

[Automated image analysis of lateral roentgen images of the spine using anatomic models]. / Automatisierte Bilderkennung lateraler Röntgenaufnahmen der Wirbelsäule mit Form Modellen.

PURPOSE: Development of a software for fully automated image analysis of lateral lumbar spine X-rays. MATERIAL AND METHOD: Using the concept of active shape models, we developed a software that produces a form model of the lumbar spine from lateral lumbar spine radiographs and runs an automated image segmentation. This model is able to detect lumbar vertebrae automatically after the filtering of digitized X-ray images. The model was trained with 20 lateral lumbar spine radiographs with no pathological findings before we evaluated the software with 30 further X-ray images which were sorted by image quality ranging from one (best) to three (worst). There were 10 images for each quality. RESULTS: Image recognition strongly depended on image quality. In group one 52 and in group two 51 out of 60 vertebral bodies including the sacrum were recognized, but in group three only 18 vertebral bodies were properly identified. CONCLUSION: Fully automated and reliable recognition of vertebral bodies from lateral spine radiographs using the concept of active shape models is possible. The precision of this technique is limited by the superposition of different structures. Further improvements are necessary. Therefore standardized image quality and enlargement of the training data set are required.

Allergic cross-reactions between cat and pig serum albumin. Study at the protein and DNA levels.

After observing a patient allergic to cat dander and pork but devoid of other allergies, we prospectively screened patients known to be allergic to cat for a second sensitization to pork. After collecting the sera of 10 young patients found to contain specific IgE to cat dander and pork, we undertook this study to detect the possible cross-reactive allergen, define its molecular characteristics, and evaluate its clinical relevance. Through immunoblotting techniques, cat and porcine serum albumin were found to be jointly recognized molecules. These findings were further analyzed by specific anti-albumin IgE titrations and cross-inhibition experiments. Cat serum albumin cDNA was obtained from cat liver, and the corresponding amino acid sequence was deduced and compared to the known porcine and human serum albumin sequences. Inhibition experiments showed that the spectrum of IgE reactivity to cat serum albumin completely contained IgE reactivity to porcine serum albumin, suggesting that sensitization to cat was the primary event. In two cohorts of cat-allergic persons, the frequency of sensitization to cat serum albumin was found to lie between 14% and 23%. Sensitization to porcine albumin was found to lie between 3% and 10%. About 1/3 of these persons are likely to experience allergic symptoms in relation to pork consumption. Sensitization to cat serum albumin should be considered a useful marker of possible cross-sensitization not only to porcine serum albumin but also to other mammalian serum albumins.

Production and characterization of monoclonal antibodies directed against high and low molecular weight kininogens.

HMWK and LMWK were purified from human plasma by ion exchange and affinity chromatography and used to raise anti-kininogen monoclonal antibodies. The Ig class and affinity of these Mab's that are directed at the heavy chain of the kininogens, were determined. Plasma samples of two patients, one with acquired C1-inhibitor deficiency and angioedema and one with idiopathic angioedema were analized by immunoblotting with these Mab's. Both were found to have cleaved HMWK during clinical attacks.

A 6,000-year sedimentary molecular record of chemocline excursions in the Black Sea.

The Black Sea is the world's largest anoxic basin; it is also a contemporary analogue of the environment in which carbonaceous shales and petroleum source beds formed. Recently, Repeta et al. reported that anoxygenic photosynthesis may be an important component of carbon cycling in the present Black Sea, owing to a shoaling of the chemocline and consequent penetration of the photic zone by anaerobic waters in the past few decades. It has been suggested that this was due to an anthropogenic decrease in freshwater input to the Black Sea, although natural causes were not ruled out. Here we report the distributions of sequestered photosynthetic pigments in eight core samples of sediments from the Black Sea ranging in age from zero to 6,200 years before the present. Our results show that photosynthetic green sulphur bacteria (Chlorobiaceae [correction of Clorobiaceae]) have been active in the Black Sea for substantial periods of time in the past. This finding indicates that the penetration of the photic zone by anaerobic waters is not a recent phenomenon, and suggests that natural causes for shoaling of the chemocline are more likely than anthropogenic ones.

The combined application of organic sulphur and isotope geochemistry to assess multiple sources of palaeobiochemicals with identical carbon skeletons.

Five immature sediments from a Messinian evaporitic basin, representing one evaporitic cycle, were studied using molecular organic sulphur and isotope geochemistry. It is shown that a specific carbon skeleton which is present in different "modes of occurrence" ("free" hydrocarbon, alkylthiophene, alkylthiolane, alkyldithiane, alkylthiane, and sulphur-bound in macromolecules) may have different biosynthetic precursors which are possibly derived from different biota. It is demonstrated that the mode of occurrence and the carbon isotopic composition of a sedimentary lipid can be used to "reconstruct" its biochemical precursor. This novel approach of recognition of the suite of palaeobiochemicals present during the time of deposition allows for identification of the biological sources with an unprecedented specificity.

Recognition of paleobiochemicals by a combined molecular sulfur and isotope geochemical approach.

Study of organic matter in immature sediments from a Messinian evaporitic basin shows that consideration of structures, modes of occurrence, and carbon isotopic compositions of free and sulfur-bound carbon skeletons allow identification of biochemical precursors. Detailed information concerning biotic communities present during deposition of sediments can be retrieved in this way. Moreover, unprecedented biochemicals were recognized; these extend the horizon of biomarker geochemistry.

Fluorometric in vivo determination of Bacillus subtilis and phage 2C DNA.

The validity of in vivo fluorometric assays was ascertained for phage and bacterial DNA measurements. The following parameters were determined by this simple technique. The DNA content of dividing cells of Bacillus subtilis 168/2 was 2.65 times higher than in resting cells. Assuming that resting cells harbor 1 genomic equivalent, its Mr was estimated to be 4.4 x 10(9) Da. A polymerization rate during growth of 788,000 bp min-1/cell is accounted for by a multifork replication mechanism. Both phage and host DNA could be measured accurately during the lytic cycle. Phage 2C DNA synthesis proceeded at a linear rate of 5.2 genome equivalents min-1.

[Mucinosis follicularis. Histologic and electron microscopy studies]. / Mucinosis follicularis. Histologische und elektronenmikroskopische Untersuchungen.

We studied a case of idiopathic mucinosis follicularis which persisted for 7 months. Histologically, the strong pathological changes began within the sebaceous glands and secondarily occurred in other parts of the pilosebaceous unit. We could demonstrate by electron microscopy that all the follicular cells in this process were undifferentiated sebaceous cells. Therefore, we think that the pathogenesis of mucinosis follicularis originates from a disturbance in the differentiation process of sebaceous cells.