Vertikaler Wasser- und Nitrattransport in tiefere Bodenschichten süddeutscher Ackerstandorte

Vertical water and nitrate movement into deeper soil layers on fields located in the south of Germany In Southern Bavaria, selected fields from deep loess and sandy sediments were sampled to a depth of maximum 10 m every 4 months, in order to determine the basic processes of water and nitrate movement in the course of the year. The downward movement of water and nitrate followed the principle of piston flow only in the intermediate vadose zone of loess soils with a leaching distance amounting 0.8 m per year. On the other hand, an accelerated as well as a delayed transport was observed in the zone of evapotranspiration of loess soils and in the whole profile of sandy soils, not being in accordance with the simple simulation model FLOTRA based on the classic theories of transport (Darcy flow, convection-dispersion-equation). Preferential flow led to the leaching of nitrate from the top soil to the lower boundary of the evapotranspiration zone of loess soils in 2 m depth, in winter and spring. In sandy soils nitrate was leached to the groundwater table in 4–6 m depth after extensive rainfall.     

Axonal neuregulin-1 regulates myelin sheath thickness

In the nervous system of vertebrates, myelination is essential for rapid and accurate impulse conduction. Myelin thickness depends on axon fiber size. We use mutant and transgenic mouse lines to show that axonal Neuregulin-1 (Nrg1) signals information about axon size to Schwann cells. Reduced Nrg1 expression causes hypomyelination and reduced nerve conduction velocity. Neuronal overexpression of Nrg1 induces hypermyelination and demonstrates that Nrg1 type III is the responsible isoform. We suggest a model by which myelin-forming Schwann cells integrate axonal Nrg1 signals as a biochemical measure of axon size.     

Nitrite, an electron donor for anoxygenic photosynthesis

We report a previously unknown process in which anoxygenic phototrophic bacteria use nitrite as an electron donor for photosynthesis. We isolated a purple sulfur bacterium 98% identical to Thiocapsa species that stoichiometrically oxidizes nitrite to nitrate in the light. Growth and nitrate production strictly depended on both light and nitrite. This is the first known microbial mechanism for the stoichiometric oxidation of nitrite to nitrate in the absence of oxygen and the only known photosynthetic oxidation in the nitrogen cycle. This work demonstrates nitrite as the highest-potential electron donor for anoxygenic photosynthesis known so far.     

Stable carbon cycle-climate relationship during the Late Pleistocene

A record of atmospheric carbon dioxide (CO2) concentrations measured on the EPICA (European Project for Ice Coring in Antarctica) Dome Concordia ice core extends the Vostok CO2 record back to 650,000 years before the present (yr B.P.). Before 430,000 yr B.P., partial pressure of atmospheric CO2 lies within the range of 260 and 180 parts per million by volume. This range is almost 30% smaller than that of the last four glacial cycles; however, the apparent sensitivity between deuterium and CO2 remains stable throughout the six glacial cycles, suggesting that the relationship between CO2 and Antarctic climate remained rather constant over this interval.     

Dimensionality control of electronic phase transitions in nickel-oxide superlattices

The competition between collective quantum phases in materials with strongly correlated electrons depends sensitively on the dimensionality of the electron system, which is difficult to control by standard solid-state chemistry. We have fabricated superlattices of the paramagnetic metal lanthanum nickelate (LaNiO(3)) and the wide-gap insulator lanthanum aluminate (LaAlO(3)) with atomically precise layer sequences. We used optical ellipsometry and low-energy muon spin rotation to show that superlattices with LaNiO(3) as thin as two unit cells undergo a sequence of collective metal-insulator and antiferromagnetic transitions as a function of decreasing temperature, whereas samples with thicker LaNiO(3) layers remain metallic and paramagnetic at all temperatures. Metal-oxide superlattices thus allow control of the dimensionality and collective phase behavior of correlated-electron systems.     

Epidemiology of canine glaucoma presented to University of Zurich from 1995 to 2009. Part 2: secondary glaucoma (217 cases)

Objective To investigate the epidemiology of canine secondary glaucomas in the cases presented to the University of Zurich, Vetsuisse Faculty (UZH) from 1995 to 2009 focusing on possible risk factors for developing secondary glaucoma in this population of dogs. Methods Information was obtained from the computer database of patients examined by members of the UZH Ophthalmology Service, between January 1995 and August 2009. Secondary glaucoma was diagnosed based on the presence of antecedent eye conditions. The data was evaluated for breed, gender, age at presentation, and for antecedent eye conditions known to cause glaucoma including anterior uveitis of unknown cause (AU), lens luxation (LL), intraocular surgery (SX), intraocular neoplasia (IN), unspecified trauma to the globe (T), ocular melanosis (OM), hypermature cataract (PY), hyphema (HY), and six other less frequent conditions. Results A total of 217 dogs were diagnosed with secondary glaucoma from 1995 to 2009. The age of the dogs with secondary glaucoma ranged between 88 days and 19 years (mean 7.7 ± 3.6 years). Data suggested a predisposition for secondary glaucoma in the Cairn Terrier and the Jack Russell Terrier breeds from 2004 to 2009. Common causes of secondary glaucoma from 1995 to 2009 were AU (23.0%), LL (22.6%), SX (13.4%), IN (10.6%), T (8.3%), OM and PY (both 6.9%) and HY (3.23%). Conclusion The report presents the epidemiology of secondary glaucomas presented to UZH from 1995 to 2009. Fourteen risk factors were recorded for secondary glaucoma. This is the first paper documenting OM in the Swiss Cairn Terrier dog population.     

Epidemiology of canine glaucoma presented to University of Zurich from 1995 to 2009. Part 1: Congenital and primary glaucoma (4 and 123 cases)

Objective To investigate the epidemiology of canine congenital and primary glaucoma in the cases presented to the University of Zurich, Vetsuisse Faculty (UZH) from 1995 to 2009. Methods Information was obtained from the computer database of patients examined by members of the UZH Ophthalmology Service, between January 1995 and August 2009. Congenital and primary glaucoma was diagnosed based on the age of onset, the lack of evidence of any antecedent eye conditions, and/or the presence and severity of iridocorneal angle defects. The data was evaluated for breed, gender and age at presentation. Results A total of 5984 dogs presented to the UZH Ophthalmology service between 1995 and 2009. Four dogs of different breed were diagnosed with congenital glaucoma and 123 dogs were diagnosed with primary glaucoma. For the primary glaucomas the overall male to female ratio (M:F) was 1:1.41 and the age of onset ranged from 0.12 to 18.3 years with a mean of 7.3 ± 3.6 years. Data suggested a predisposition for primary glaucoma in the Siberian Husky, Magyar Vizsla and Newfoundland from 2004 to 2009. Conclusion The report presents the epidemiology of canine congenital and primary glaucomas presented to the UZH from 1995 to 2009. A previous suspicion of predisposition for primary glaucoma in the Newfoundland dog (n = 6) and the Magyar Vizsla breed (n = 8) was confirmed.     

Natural and anthropogenic components of soil acidification

The following 8 theses are theoretically founded and experimentally quantified. 1. Rocks contain only bases and no acid precursors. Therefore, with the exception of sulfide containing rocks, soils cannot acidify as a result of atmospheric rock weathering. 2. A consumption of protons in rocks and soils results in a decrease of their acid neutralizing capacity (ANC) and can result in the buildup of a base neutralizing capacity (BNC). Strong soil acidification leads to the formation of stronger acids from weaker acids in the solid phase; this may be connected with a decrease in the BNC. 3. Weak acids (carbonic acid) lead in geological times to the depletion of bases without a larger accumulation of labile cation acids. Strong acids (HNO₃, organic acids, H₂SO₄) can lead within a few decades to soil acidification, i.e. to leaching of nutrient cations and the accumulation of labile cation acids. 4. The acid input caused by the natural emission of SO₂ and NO_x can be buffered by silicate weathering even in soils low in silicates. 5. The cause of soil impoverishment and soil acidification is a decoupling of the ion cycle in the ecosystem. 6. Acid deposition in forest ecosystems which persists over decades leads to soil acidification. 7. Formation and deposition of strong acids with conservative anions (SO₄, NO₃) shifts soil chemistry into the Al or Al/Fe buffer range up to great soil depth. In such soils eluvial conditions prevail throughout the solum and even in upper part of the C horizon: in connection with the decomposition of clay minerals, Al and eventually Fe are being eluviated. The present soil classification does not include this soil forming process. 8. In the long run, soil acidification by acid deposition results in the retraction of the root system of acid tolerant tree species from the mineral soil, and in water acidification.