Annual report 2006 // Institute of Radiochemistry

[no abstract available

Mykorrhiza im ökologischen Landbau

The mycorrhizal symbiosis plays a major role in plant nutrient acquisition, pathogen control and soil stabilisation in land use systems with a low input of external resources. The use of inocula of mycorrhizal fungi for the development of sustainable agricultural production systems in Europe is still scarce. Since it was found that even in organically managed soils and particularly in substrates mycorrhizas can be limited, a set of recently introduced commercial inocula and 10 pre-selected strains of mycorrhizal fungi were multiplied and screened under farm conditions. Poinsettia, Pelargonium, leak and strawberry were used as test plants, which were inoculated in the seeding or potting substrates. There was a strong interaction between mycorrhizal fungi strains and crop. Mycorrhiza effects were found to be most pronounced in early seedling stages and, therefore, this phase of development should be investigated more intensively applying a combination of selected mycorrhizal fungal strains

Spectral Boundary of Positive Random Potential in a Strong Magnetic Field

We consider the problem of randomly distributed positive delta-function scatterers in a strong magnetic field and study the behavior of density of states close to the spectral boundary at $E=\hbar\omega_{c}/2$ in both two and three dimensions. Starting from dimensionally reduced expression of Brezin et al. and using the semiclassical approximation we show that the density of states in the Lifshitz tail at small energies is proportio- nal to $e^{f-2}$ in two dimensions and to $\exp(-3.14f\ln(3.14f/\pi e)/ \sqrt(2me))$ in three dimensions, where $e$ is the energy and $f$ is the density of scatterers in natural units.Comment: 12 pages, LaTex, 5 figures available upon request, to appear in Phys. Rev.

Hall resistance in the hopping regime, a "Hall Insulator"?

The Hall conductivity and resistivity of strongly localized electrons at low temperatures and at small magnetic fields are obtained. It is found that the results depend on whether the conductivity or the resistivity tensors are averaged to obtain the macroscopic Hall resistivity. In the second case the Hall resistivity always {\it diverges} exponentially as the temperature tends to zero. But when the Hall resistivity is derived from the averaged conductivity, the resulting temperature dependence is sensitive to the disorder configuration. Then the Hall resistivity may approach a constant value as $T\to 0$. This is the Hall insulating behavior. It is argued that for strictly dc conditions, the transport quantity that should be averaged is the resistivity.Comment: Late

Electron-Electron Interactions and the Hall-Insulator

Using the Kubo formula, we show explicitly that a non-interacting electron system can not behave like a Hall-insulator, {\it ie.,} a DC resistivity matrix $\rho_{xx}\rightarrow\infty$ and $\rho_{xy}=$finite in the zero temperature limit, as has been observed recently in experiment. For a strongly interacting electron system in a magnetic field, we illustrate, by constructing a specific form of correlations between mobile and localized electrons, that the Hall resistivity can approximately equal to its classical value. A Hall-insulator is realized in this model when the density of mobile electrons becomes vanishingly small. It is shown that in non-interacting electron systems, the zero-temperature frequency-dependent conductacnce generally does not give the DC conductance.Comment: 11 pages, RevTeX3.

Molecular epidemiology of SARS-CoV-2: a regional to global perspective

Background After a year of the global SARS-CoV-2 pandemic, a highly dynamic genetic diversity is surfacing. Among nearly 1000 reported virus lineages, dominant lineages such as B.1.1.7 or B.1.351 attract media attention with questions regarding vaccine efficiency and transmission potential. In response to the pandemic, the Jena University Hospital began sequencing SARS-CoV-2 samples in Thuringia in early 2020.Methods Viral RNA was sequenced in tiled amplicons using Nanopore sequencing. Subsequently, bioinformatic workflows were used to process the generated data. As a genomic background, 9,642 representative SARS-CoV-2 genomes (1,917 of German origin) were extracted from more than 300.000 genomes.Results In a comprehensive bioinformatics analysis, we have set Thuringian isolates in the German, European and global context. In Thuringia, a largely rural German region without an international airport and a population density below the German average, we discovered many of the common “EU lineages”. German samples are scattered across eight major clades, and Thuringian samples occupy four of them.Conclusion The rapid emergence and spread of novel variants are of great concern as these lineages could transmit more efficiently, evade current vaccine efforts or undermine diagnostic test accuracy. To anticipate and mitigate these threats, a continuous molecular surveillance is essential.Key messagesBioinformatics analysis of 1,917, 4,251, and 3,474 SARS-CoV-2 genomes from Germany, the EU (except Germany), and non-EU, respectively, subsampled from more than 300,000 public genomes and placed in the context of Thuringian sequencesConstant antigenic drift for SARS-CoV-2 and no clear pattern or clustering is visible in Thuringia based on the current number of samplesCurrently over 100 described lineages are identified in Germany and only a subset (9) are detected in Thuringia so far, most likely due to genetic undersamplingFrom a national perspective, it is likely that high-frequency lineages, which are currently spreading throughout Europe, will eventually also reach ThuringiaSystematic and dense molecular surveillance via whole-genome sequencing is needed to detect concerning new lineages early, limit spread and adjust vaccines if necessaryCompeting Interest StatementThe authors have declared no competing interest.Funding StatementThe work is funded by the German Ministry of Education and Research (BMBF), grant number 01KX2021, and the Thuringian Region Government, grant number TZUZI82094.Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:not applicableAll necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesAll data is available on GISAID.Introduction Methods - Nanopore sequencing and genome reconstruction - Time tree creation Results - Most highly prevalent SARS-CoV-2 lineages in Germany detected in Thuringia - Genetic divergence and current lineage distribution Discussio

Influence of clinical and gait analysis experience on reliability of observational gait analysis (Edinburgh Gait Score Reliability)

AbstractObjectivesTreatment complexity of cerebral palsy (CP) patients imposes outcome evaluation studies, which may include objective technical analysis and more subjective functional evaluation. The Edinburgh Gait Score (EGS) was proposed as an additive or alternative when complex instrumented three-dimensional gait analysis is not available. Our purposes were to apply a translated EGS to standard video recordings of independent walking spastic diplegic CP patients, to evaluate its intraobserver and interobserver reliability with respect to gait analysis familiar and not familiar observers.MethodsTen standard video recordings acquired during routine clinical gait analysis were examined by eight observers gait analysis interpretation experienced or not, out of various specialities, two times with a two weeks interval. Kappa statistics and intraclass correlation coefficient were calculated.ResultsBetter reliability was observed for foot and knee scores than in proximal segments with significant differences between stance and swing phase. Significantly better results in gait analysis trained observers underlines the importance to either be used to clinical gait analysis interpretation, or to benefit of video analysis training before observational scoring.ConclusionVisual evaluation may be used for outcome studies to explore clinical changes in CP patients over time and may be associated to other validated evaluation tools

Tail States in a Superconductor with Magnetic Impurities

A field theoretic approach is developed to investigate the profile and spectrum of sub-gap states in a superconductor subject to a weak magnetic impurity potential. Such states are found to be associated with inhomogeneous supersymmetry broken instanton configurations of the action.Comment: 4 pages, 2 eps figure