Development of Collembolans after coversion towards organic farming

In Northern Germany, a diverse and complex experimental farm of the Federal Agricultural Research Centre (FAL) was set-up in 2001 covering all main aspects of organic farming. Previously, the 600 ha farm had been managed conventionally. Adjacent conventional farms were used as reference. The aim of this project was to study collembolans, microbial biomass and soil organic carbon in six organically farmed fields managed as a crop rotation of six different crops compared with an adjacent conventionally managed field. We hypothesised that the specific management in organic farming promotes soil biota. Soil samples were taken during the growing season in 2004. Collembolan abundances and microbial biomass were lower under organic management, but, generally, collembolan diversity was higher in organically farmed fields combined with a shifting in the dominance structure of the species. This result reveals that, even after three years, the soil biota is still changing with management conversion

Mixed cropping systems for control of weeds and pests in organic oilseed crops

Agricultural advantages of mixed cropping are gained from biological effects like light competition offering weed-suppressing capacities, or by diversification of plant covers to break development cycles of pests. These effects were measured in a two-year project on mixed cropping with organic oilseed crops. It was found that weeds can be efficiently suppressed in organic linseed (Linum usitatissivum) grown in combination with wheat (Triticum aestivum) or false flax (Camelina sativa). Linseed growth was, however, impaired. In organic pea production (Pisum sativum) also, growing the crop as a mixture with false flax led to a significant decrease of weed population. Either culture showed a balanced plant development. In winter rape (Brassica napus) there were suggestions that infestation by insect pests can be directly reduced in mixtures with cereals or legumes and that parasitoids of insect pests are supported

Contribution of organic farming to conserving and improving biodiversity in Germany avi-fauna as an example

Although it is the aim of organic farming to increase biodiversity, there is little information about the impact of organic farming on birds. From 2001 to 2003, the number of breeding birds was recorded annually on the organic experimental farm of the Institute of Organic Farming (600 ha), and on adjacent conventional and organic farms (60 ha and 40 ha) in Northern Germany. The number of skylark (Alauda arvensis) territories increased considerably after the conversion from conventional to organic farming on the premises of the Institute. Their number remained unvaried on the conventional farm. The highest density of skylark territories was found on the farm which has been under organic management for many years. The number of yellowhammer (Emberiza citronella) territories fluctuated largely in relation to the availability of field margin strips, both on conventional and organic land. During the breeding season aerial hunters (swallows and swifts) and raptors significantly preferred organic fields. Outside the breeding season, densities of raptors (in autumn and in winter), seed-eating birds (in autumn) and insect-eating birds (in autumn) were significantly higher on organic than on conventional fields

Comparative monolayer investigations of surface properties of negatively charged glycosphingolipids from vertebrates (gangliosides) and invertebrates (SGL-II, lipid IV).

The surface properties of four negatively charged glycosphingolipids from vertebrates, the sialo-glycosphingolipids (=gangliosides) GM1, GD1a, GT1b and a sulfo-glycosphingolipid (=sulfatide), and of the two negatively charged glycosphingolipids from lower invertebrates, the glucurono-glycosphingolipid Lipid IV and the aminophosphono-glycosphingo-lipid SGL-II were investigated in monolayers at the air/water interface. The molecular peculiarities under investigation were surface pressure (π) and surface potential (ΔV) which are described for Lipid IV and SGL-II for the first time. The surface pressure/area isotherms of all glycosphingolipids were typical of a liquid-expanded monolayer and, with the exception of SGL-II, exhibited a phase transition to a liquid-condensed state at surface pressures above 20 mN/m. The surface potential/molecular area data found for gangliosides in the closely packed state at π=30 mN/m (GM1: ΔV = −17 mV; GD1a: ΔV = −35 mV; GT1b: ΔV = −39 mV) showed only a slight influence of the additional number of negatively charged residues. For Lipid IV, the surface behavior was very similar to GM1 both possessing one negative group per molecule, whereas in SGL-II also the surface potential data (ΔV = −173 mV) were different compared with GD1a both possessing two negative groups per molecule. The addition of Ca2+ condensed the monolayers of all glycolipids and increased the potential in the direction to more positive values, but these findings were less effective in SGL-II films. On the basis of monolayer results presented here, in biological membranes of invertebrates especially Lipid IV might play a similar role as the ganglioside GM1 in vertebrate cells

Surface potentials and electric dipole moments of ganglioside and phospholipid bilayers: Contribution of the polar headgroup at the water/lipid interface.

Monolayers of different gangliosides (GM1, GD1a, GT1b, GMix), ceramide (Cer), sulfatide (Sulf), phospholipids (DOPC, DPPE, DPPS, DOPA), a quaternary ammonium salt (DOMA) and fatty acids (C16, C18, C20) were investigated at the air/water interface on pure water as well as on buffered subphases. Monolayers at the air/water interface consist of two interfaces: the water/lipid and the lipid/air interfaces. The normal components of the effective total dipole moments (Δμ), the effective local dipole moments (Δμα) and effective local surface potentials (ΔVα) of polar headgroups at the water/lipid interface have been calculated from surface potential (ΔV) and mean molecular area (A) measurements of close-packed monolayers. The contribution of the lipid/air interface was previously determined experimentally by partial dipole compensation approach (Vogel, V. and Möbius, D. (1988) Thin Solid Films 159, 73–81). The surface potentials (ΔV) of ganglioside monolayers are quite similar (e.g., GMI = −17 mV, GTib = −39 mV; at surface pressure π = 30 mN/m triethanolamine (TEA)/HCl buffer, pH 7.4, as subphase); this indicates that variations in molecular structure of gangliosides like the influence of the number of negative charges per ganglioside which lead to appreciate changes in the average molecular packing do not cause large changes in surface potential. The local surface potentials (ΔVα) reach to minus several hundred millivolts for nearly all compounds, but clear differences are shown between negatively charged phospholipids (e.g., DPPS = −296 mV at π = 30 mN/m) and glycolipids (e.g., GM1 = −413 mV), and within glycolipids at different surface pressures (e.g., GD1n: − 342 mV at π = 20 mN/m versus −453 mV at π = 30mN/m nly in gangliosides (except for GD1b) the total dipole moments (Δμ) are negative (−0.029 up to − 0.078 D) and directed to the water. Unlike DOPC (+0.069 D) and DOMA (+0.421 D), the local dipole moments (Δμα of all hydrated polar headgroups are negative (e.g., DPPS = −0.331 D; GM1 = −0.729 D) and directed from the monolayer (−) to the water (+). Under well-defined conditions investigated such data are helpful for a better understanding of the large functional role of gangliosides especially in determining the surface potential of biological membranes

Investigation of DFIG with Fault RideThrough Capability

Abstract--In this paper, the ability of doubly fed induction generators to provide voltage stability support in weak transmission networks is investigated. Specifically, the response of wind turbines to voltage dips at the point of common coupling and its effects on system stability are analyzed. A control strategy for the operation of the grid and rotor side converters is developed in order to support the grid voltage by injecting reactive power during and after grid fault events. The performance of the strategy is analyzed for different voltage dips at the point of common coupling of a wind farm and compared with the case when the converters do not provide any voltage support. Simulations are performed using a simplified model of the Chilean transmission network. This system is considered to be a good example of weak power system, because of its radial configuration

Deep sequencing reveals differential expression of microRNAs in favorable versus unfavorable neuroblastoma

Small non-coding RNAs, in particular microRNAs(miRNAs), regulate fine-tuning of gene expression and can act as oncogenes or tumor suppressor genes. Differential miRNA expression has been reported to be of functional relevance for tumor biology. Using next-generation sequencing, the unbiased and absolute quantification of the small RNA transcriptome is now feasible. Neuroblastoma(NB) is an embryonal tumor with highly variable clinical course. We analyzed the small RNA transcriptomes of five favorable and five unfavorable NBs using SOLiD next-generation sequencing, generating a total of >188 000 000 reads. MiRNA expression profiles obtained by deep sequencing correlated well with real-time PCR data. Cluster analysis differentiated between favorable and unfavorable NBs, and the miRNA transcriptomes of these two groups were significantly different. Oncogenic miRNAs of the miR17-92 cluster and the miR-181 family were overexpressed in unfavorable NBs. In contrast, the putative tumor suppressive microRNAs, miR-542-5p and miR-628, were expressed in favorable NBs and virtually absent in unfavorable NBs. In-depth sequence analysis revealed extensive post-transcriptional miRNA editing. Of 13 identified novel miRNAs, three were further analyzed, and expression could be confirmed in a cohort of 70 NBs

Efficient and accurate P-value computation for Position Weight Matrices

<p>Abstract</p> <p>Background</p> <p>Position Weight Matrices (PWMs) are probabilistic representations of signals in sequences. They are widely used to model approximate patterns in DNA or in protein sequences. The usage of PWMs needs as a prerequisite to knowing the statistical significance of a word according to its score. This is done by defining the P-value of a score, which is the probability that the background model can achieve a score larger than or equal to the observed value. This gives rise to the following problem: Given a P-value, find the corresponding score threshold. Existing methods rely on dynamic programming or probability generating functions. For many examples of PWMs, they fail to give accurate results in a reasonable amount of time.</p> <p>Results</p> <p>The contribution of this paper is two fold. First, we study the theoretical complexity of the problem, and we prove that it is NP-hard. Then, we describe a novel algorithm that solves the P-value problem efficiently. The main idea is to use a series of discretized score distributions that improves the final result step by step until some convergence criterion is met. Moreover, the algorithm is capable of calculating the exact P-value without any error, even for matrices with non-integer coefficient values. The same approach is also used to devise an accurate algorithm for the reverse problem: finding the P-value for a given score. Both methods are implemented in a software called TFM-PVALUE, that is freely available.</p> <p>Conclusion</p> <p>We have tested TFM-PVALUE on a large set of PWMs representing transcription factor binding sites. Experimental results show that it achieves better performance in terms of computational time and precision than existing tools.</p

Anthropology and GIS: Temporal and Spatial Distribution of the Philippine Negrito Groups

The Philippine negrito groups comprise a diverse group of populations speaking over 30 different languages, who are spread all over the archipelago, mostly in marginal areas of Luzon Island in the north, the central Visayas islands, and Mindanao in the south. They exhibit physical characteristics that are different from more than 100 Philippine ethnolinguistic groups that are categorized as non-negritos. Given their numbers, it is not surprising that Philippine negritos make up a major category in a number of general ethnographic maps produced since the nineteenth century. Reports from various ethnological surveys during this period, however, have further enriched our understanding regarding the extent and distribution of negrito populations. Using the data contained in these reports, it is possible to plot and create a map showing the historical locations and distribution of negrito groups. Using geographic information systems (GIS), the location and distribution of negrito groups at any given time can be overlaid on historical or current maps. In the present study, a GIS layer was compiled and extracted from the 2000 Philippine Census of population at the village level and overlaid on existing maps of the Philippines. The maps that were generated from this project will complement ongoing anthropological and genetic studies of negrito groups that inhabit different locations within the Philippine archipelago