Regularization and Anomalies in Gauge Theory

Some of the basic issues related to the regularization and anomalies in gauge theory are reviewed, with particular emphasis on the recent development in lattice gauge theory. The generalized Pauli-Villars regularization is discussed from a view point of the covariant regularization of currents, and the construction of a regularized effective action in terms of covariant currents is compared with the lattice formulation of chiral Abelian theory.Comment: 14 pages. Talk given at NATO Advanced Research Workshop ``Lattice Fermions and Structure of the Vacuum'', October 5-9, 1999, at Dubna, Russia (To be published in the Proceedings

Gnathostomiasis nach Aufenthalt in Thailand.

During a 4-week holiday in Thailand a 13-year-old boy from Germany briefly fell ill with diarrhoea without blood-tinged stools and fever. 5 months later oedematous, reddish swellings occurred, at first on the right upper arm, later over the right side of the chest. Especially at night these swellings were associated with severe local and generalized itching. Bilaterally the axillary lymph-nodes were hard and slightly enlarged. There was a marked eosinophilia of 56%, the white count was 22,700/microliters and the serum level of IgE was raised to 1777 IU/ml. No worm eggs or larvae were found in the stool. Enzyme-linked immunosorbent assay, using larvae of Gnathostoma spinigerum as antigen, demonstrated antibodies against this nematode. Gnathostomiasis having been diagnosed treatment was started with albendazole (200 mg twice daily for 21 days), after which the boy was symptom free. After 2 months the eosinophilia had regressed to 10%, the white cell count was normal and the antibody titre had fallen

Fundusblutungen bei Malaria tropica

Ein 20jähriger Tourist mit Malaria tropica entwickelte bilaterale prä- und intraretinale Hämor-rhagien einschließlich einer Makulablutung mit reversiblem Visusverlust, der während des Rückfluges von Westafrika auftrat. Die Diagnose wurde durch die zunächst aufgesuchte Universitätsaugenklinik eingeleitet. Mögliche Pathomechanismen, okuläre Manifestationen bei Malaria und die zunehmenden Probleme mit importierter Malaria werden zusammenfassend dargestellt und besprochen.The case is presented of a 20-year-old tourist with mild falciparum malaria and bilateral preretinal and intraretinal hemorrhage, including a macular hemorrhage with reversible visual loss, which developed during his return flight from West Africa. The diagnosis was initiated by the university eye hospital originally consulted. Possible pathogenic mechanisms, ocular findings in malaria, and the increasing problems of imported malaria are summarized and reviewed

Dissolved N:P ratio changes in the eastern tropical North Atlantic: effect on phytoplankton growth and community structure

Previous bioassays conducted in the oligotrophic Atlantic Ocean identified availability of inorganic nitrogen (N) as the proximate limiting nutrient control of primary production, but additionally displayed a synergistic growth effect of combined N and phosphorus (P) addition. To classify conditions of nutrient limitation of coastal phytoplankton in the tropical ocean, we performed an 11 d nutrient-enrichment experiment with a natural phytoplankton community from shelf waters off northwest Africa in shipboard mesocosms. We used pigment and gene fingerprinting in combination with flow cytometry for classification and quantification of the taxon-specific photoautotrophic response to differences in nutrient supply. The developing primary bloom was dominated by diatoms and was significantly higher in the treatments receiving initial N addition. The combined supply of N and P did not induce a further increase in phytoplankton abundance compared to high N addition alone. A secondary bloom during the course of the experiment again displayed higher primary producer standing stock in the N-fertilized treatments. Bacterial abundance correlated positively with phytoplankton biomass. Dominance of the photoautotrophic assemblage by N-limited diatoms in conjunction with a probable absence of any P-limited phytoplankton species prevented an additive effect of combined N and P addition on total phytoplankton biomass. Furthermore, after nutrient exhaustion, dinitrogen (N-2)-fixing cyanobacteria succeeded the bloom-forming diatoms. Shelf waters in the tropical eastern Atlantic may thus support growth of diazotrophic cyanobacteria such as Trichodesmium sp. subsequent to upwelling pulses

Detection of viable Mycobacterium ulcerans in clinical samples by a novel combined 16S rRNA reverse transcriptase/IS2404 real-time qPCR assay.

Detection of Viable <em>Mycobacterium ulcerans</em> in Clinical Samples by a Novel Combined 16S rRNA Reverse Transcriptase/IS<em>2404</em> Real-Time qPCR Assa

Lattice chiral symmetry, CP-violation and Majorana fermions

A brief summary of lattice fermions defined by the general Ginsparg-Wilson algebra is first given. It is then shown that those general class of fermion operators have a conflict with CP invariance in chiral gauge theory and with the definition of Majorana fermions in the presence of chiral-symmetric Yukawa couplings. The same conclusion holds for the domain-wall fermion also

Production of oceanic nitrous oxide by ammonia-oxidizing archaea

The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA) over their bacterial counterparts (AOB) in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O) that occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been reported to produce N2O. Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA) were detectable throughout the water column of the eastern tropical North Atlantic (ETNA) and eastern tropical South Pacific (ETSP) Oceans. Particularly in the ETNA, comparable patterns of abundance and expression of archaeal amoA genes and N2O co-occurred in the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved oxygen in the ocean

One-Flavour Hybrid Monte Carlo with Wilson Fermions

The Wilson fermion determinant can be written as product of the determinants of two hermitian positive definite matrices. This formulation allows to simulate non-degenerate quark flavors by means of the hybrid Monte Carlo algorithm. A major numerical difficulty is the occurrence of nested inversions. We construct a Uzawa iteration scheme which treats the nested system within one iterative process.Comment: 11 pages, to appear in proceedings of the workshop "Numerical Challenges in Lattice QCD", Springer Verla

Low oxygen eddies in the eastern tropical North Atlantic: Implications for N2O cycling

Nitrous oxide (N2O) is a climate relevant trace gas, and its production in the ocean generally increases under suboxic conditions. The Atlantic Ocean is well ventilated, and unlike the major oxygen minimum zones (OMZ) of the Pacific and Indian Oceans, dissolved oxygen and N2O concentrations in the Atlantic OMZ are relatively high and low, respectively. This study, however, demonstrates that recently discovered low oxygen eddies in the eastern tropical North Atlantic (ETNA) can produce N2O concentrations much higher (up to 115 nmol L−1) than those previously reported for the Atlantic Ocean, and which are within the range of the highest concentrations found in the open-ocean OMZs of the Pacific and Indian Oceans. N2O isotope and isotopomer signatures, as well as molecular genetic results, also point towards a major shift in the N2O cycling pathway in the core of the low oxygen eddy discussed here, and we report the first evidence for potential N2O cycling via the denitrification pathway in the open Atlantic Ocean. Finally, we consider the implications of low oxygen eddies for bulk, upper water column N2O at the regional scale, and point out the possible need for a reevaluation of how we view N2O cycling in the ETNA

N2 fixation in eddies of the eastern tropical South Pacific Ocean

Mesoscale eddies play a major role in controlling ocean biogeochemistry. By impacting nutrient availability and water column ventilation, they are of critical importance for oceanic primary production. In the eastern tropical South Pacific Ocean off Peru, where a large and persistent oxygen deficient zone is present, mesoscale processes have been reported to occur frequently. However, investigations on their biological activity are mostly based on model simulations, and direct measurements of carbon and dinitrogen (N2) fixation are scarce. We examined an open ocean cyclonic eddy and two anticyclonic mode water eddies: a coastal one and an open ocean one in the waters off Peru along a section at 16° S in austral summer 2012. Molecular data and bioassay incubations point towards a difference between the active diazotrophic communities present in the cyclonic eddy and the anticyclonic mode water eddies. In the cyclonic eddy, highest rates of N2 fixation were measured in surface waters but no N2 fixation signal was detected at intermediate water depths. In contrast, both anticyclonic mode water eddies showed pronounced maxima in N2 fixation below the euphotic zone as evidenced by rate measurements and geochemical data. N2 fixation and carbon (C) fixation were higher in the young coastal mode water eddy compared to the older offshore mode water eddy. A co-occurrence between N2 fixation and biogenic N2, an indicator for N loss, indicated a link between N loss and N2 fixation in the mode water eddies, which was not observed for the cyclonic eddy. The comparison of two consecutive surveys of the coastal mode water eddy in November and December 2012 revealed also a reduction of N2 and C fixation at intermediate depths along with a reduction in chlorophyll by half, mirroring an aging effect in this eddy. Our data indicate an important role for anticyclonic mode water eddies in stimulating N2 fixation and thus supplying N offshore