Reappraising the theme of breeding systems in Echinococcus: is outcrossing a rare phenomenon?

Selfing has been considered the most common mode of reproduction in Echinococcus flatworms. However, population genetic studies on the asexual larval stage involving nuclear co-dominant markers have not always revealed significant heterozygote deficiencies - the expected outcome of a regularly and highly inbred population. In this study, we analysed the genetic structure of Echinococcus granulosus sensu lato populations from Southern Brazil during their adult (sexual) stage using 1 mitochondrial and 1 nuclear marker (cox 1 and mdh, respectively). We show that parasite genetic differentiation is largest among definitive hosts (domestic dogs) from different farms, suggesting that transmission is mostly maintained within a farm. Moreover, we show that heterozygote deficiencies are not significant, and we suggest that outbreeding is the most common mode of reproduction of the parasite in that regio

Eine neue In-vivo-Technik zur dreidimensionalen Analyse der Translation der Femurkondylen und der Menisken unter dem Einfluß antagonistischer Muskelkräfte

The aim of our study was to develop a 3-D MR-based technique for the analysis of meniscal and femoral translations during flexion of the knee, and under the influence of antagonistic muscle forces in healthy subjects. In an open MR system, 5 knees were examined at 30 degrees and 90 degrees flexion using a T1-weighted 3-D gradient echo sequence. A force of 30 Newtons, first in the extending and then in the flexing direction, was applied to the distal lower leg. After three-dimensional reconstruction, the minimal distances between the centre of the tibial plateau and the posterior edge of the menisci and femoral condyles were determined. At 30 degrees flexion, the minimum distance for the meniscus was larger medially than laterally (23.2 +/- 1.8 mm vs. 16.2 +/- 3.3 mm), and this also applied to the condyles (25.1 +/- 1.5 vs. 19.0 +/- 3.0 mm). During flexion to 90 degrees, a posterior translation of 0.5 +/- 0.2 mm was observed for the lateral, and of 3.4 +/- 1.2 mm for the medial, meniscus. The condyles demonstrated a different posterior translation (lateral 2.2 +/- 0.56 mm; medial 1.8 +/- 1.9 mm). No obvious differences were found between extension and flexion muscle activity for the different positions of the knee. In the present study, a new 3-D technique is presented for the analysis of the femoral and meniscal translation at various positions of the knee, and under muscle activity. The results suggest different translation for the menisci and condyles

SICANE: a Detector Array for the Measurement of Nuclear Recoil Quenching Factors using Monoenergetic Neutron Beam

SICANE is a neutron scattering multidetector facility for the determination of the quenching factor (ratio of the response to nuclear recoils and to electrons) of cryogenic detectors used in direct WIMP searches. Well collimated monoenergetic neutron beams are obtained with inverse (p,n) reactions. The facility is described, and results obtained for the quenching factors of scintillation in NaI(Tl) and of heat and ionization in Ge are presented.Comment: 30 pages, Latex, 11 figures. Submitted to NIM

Theoretical Directional and Modulated Rates for Direct SUSY Dark Matter Detection

Exotic dark matter together with the vacuum energy (cosmological constant) seem to dominate in the flat Universe. Thus direct dark matter detection is central to particle physics and cosmology. Supersymmetry provides a natural dark matter candidate, the lightest supersymmetric particle (LSP). Furthermore from the knowledge of the density and velocity distribution of the LSP, the quark substructure of the nucleon and the nuclear structure (form factor and/or spin response function), one is able to evaluate the event rate for LSP-nucleus elastic scattering. The thus obtained event rates are, however, very low. So it is imperative to exploit the two signatures of the reaction, namely the modulation effect, i.e. the dependence of the event rate on the Earth's motion, and the directional asymmetry, i.e. the dependence of the rate on the the relative angle between the direction of the recoiling nucleus and the sun's velocity. These two signatures are studied in this paper employing various velocity distributions and a supersymmetric model with universal boundary conditions at large tan(beta).Comment: 11 LATEX pages, 1 table and 4 ps figures included. Paper presented in DARK2002, Fourth Heidelberg International Conference on Dark Matter in Astro- and Particle Physics, Cape Town, South Africa, 4-9 February, 2002, to appear in the proceedings (to be published by Springer Verlag

Spatiotemporal phase slip patterns for visual evoked potentials, covert object naming tasks, and insight moments extracted from 256 channel EEG recordings

Phase slips arise from state transitions of the coordinated activity of cortical neurons which can be extracted from the EEG data. The phase slip rates (PSRs) were studied from the high-density (256 channel) EEG data, sampled at 16.384 kHz, of five adult subjects during covert visual object naming tasks. Artifact-free data from 29 trials were averaged for each subject. The analysis was performed to look for phase slips in the theta (4-7 Hz), alpha (7-12 Hz), beta (12-30 Hz), and low gamma (30-49 Hz) bands. The phase was calculated with the Hilbert transform, then unwrapped and detrended to look for phase slip rates in a 1.0 ms wide stepping window with a step size of 0.06 ms. The spatiotemporal plots of the PSRs were made by using a montage layout of 256 equidistant electrode positions. The spatiotemporal profiles of EEG and PSRs during the stimulus and the first second of the post-stimulus period were examined in detail to study the visual evoked potentials and different stages of visual object recognition in the visual, language, and memory areas. It was found that the activity areas of PSRs were different as compared with EEG activity areas during the stimulus and post-stimulus periods. Different stages of the insight moments during the covert object naming tasks were examined from PSRs and it was found to be about 512 ± 21 ms for the 'Eureka' moment. Overall, these results indicate that information about the cortical phase transitions can be derived from the measured EEG data and can be used in a complementary fashion to study the cognitive behavior of the brain

Entorhinal grid-like codes for visual space during memory formation

Eye movements, such as saccades, allow us to gather information about the environment and, in this way, can shape memory. In non-human primates, saccades are associated with the activity of grid cells in the entorhinal cortex. Grid cells are essential for spatial navigation, but whether saccade-based grid-like signals play a role in human memory formation is currently unclear. Here, human participants undergo functional magnetic resonance imaging and continuous eye gaze monitoring while studying scene images. Recognition memory is probed immediately thereafter. Results reveal saccade-based grid-like codes in the left entorhinal cortex that are specific to later remembered trials during study, a finding that we replicate with an independent data set. The grid-related effects are time-locked to activation increases in the frontal eye fields. Unexpectedly, lower saccade-based grid-like codes are associated with better subsequent recognition memory performance. Our findings suggest an entorhinal map of visual space that is timed with neural activity in oculomotor regions, and negatively associated with subsequent memory. Grid-like codes, entorhinal cortex, saccades, frontal eye fields (FEF), memory, functional magnetic resonance imaging (fMRI

Shoulder rhythm in patients with impingement and in controls: Dynamic RSA during active and passive abduction

Background and purpose Impingement syndrome is probably the most common cause of shoulder pain. Abnormal abduction and proximal humeral translation are associated with this condition. We evaluated whether the relative distribution between glenohumeral and scapular-trunk motions (the scapulohumeral rhythm) and the speed of motion of the arm differed between patients with impingement and a control group without shoulder symptoms

Beyond ruminants: discussing opportunities for alternative pasture uses in New Zealand

peer-reviewedThe New Zealand government has set ambitious goals for primary sector growth and of zero net carbon emissions by 2050. This presents an opportunity and obligation to develop new ideas for grassland production systems to increase export value and generate new job opportunities, while reducing environmental impacts. The aim of this paper is to draw on recent research in Europe to investigate some of the alternative and complementary uses for pasture as a feedstock for a green biorefinery. A biorefinery is a facility, or a series of processes, that convert biomass into a spectrum of value-added products. For example, protein can be extracted mechanically from green biomass once harvested. The residual fibre fraction could be used as a low-nitrogen feed for ruminants to reduce urinary nitrogen, while the liquid protein fraction could be processed to make it suitable for mono-gastric or human consumption. Enzymes can promote protein extraction and controlled conversion of insoluble plant fibres and oligosaccharides to foster gut-health promoting prebiotic food ingredients. Anaerobic digestion of residues can then be used to create energy and soilimproving products. Research and demonstration of these approaches in practice, along with the results of feasibility studies, will be required to see which of these opportunities is a good fit for New Zealand pasture systems