219 research outputs found
Increased Coprophagic Activity of the Beetle, Tenebrio molitor, on Feces Containing Eggs of the Tapeworm, Hymenolepis diminuta
When provided with fecal pellets from uninfected (control) rats and rats infected with the
tapeworm Hymenolepis diminuta, more fed and starved (72 h) female and starved male Tenebrio molitor
fed on fecal pellets from infected- than from control rats; compared to fecal pellets from controls rats, fed
males avoided the infective fecal pellets. Uninfective and infective fecal pellets had similar moisture
contents, so increased coprophagic activity was not due to differences in moisture content. Fed and
starved males and females were fed on fecal pellets containing tapeworm eggs and examined for
cysticercoids. Significantly greater numbers of starved beetles than fed beetles were infected with
cysticercoids, but the numbers of infected males and females within each treatment were not
significantly different. On the other hand, males contained significantly greater numbers of cysticercoids
than did females, and there was no significant difference between the numbers of cysticercoids recovered
from fed and starved beetles. The data support the hypothesis that the feeding behavior of T. molitor on
rat feces is altered by the presence of tapeworm eggs. The data demonstrated further that transmission
dynamics are affected by a complex interaction of the beetle's sex and nutritional status
A Summary of the asymptotic analysis for the EPRL amplitude
We review the basic steps in building the asymptotic analysis of the
Euclidean sector of new spin foam models using coherent states, for Immirzi
parameter less than one. We focus on conceptual issues and by so doing omit
peripheral proofs and the original discussion on spin structures.Comment: 8pages, Proceedings for Planck Scale 2009, talk given by Henrique
Gome
Open Database of Epileptic EEG with MRI and Postoperational Assessment of Foci—a Real World Verification for the EEG Inverse Solutions
This paper introduces a freely accessible database http://eeg.pl/epi, containing 23 datasets from patients diagnosed with and operated on for drug-resistant epilepsy. This was collected as part of the clinical routine at the Warsaw Memorial Child Hospital. Each record contains (1) pre-surgical electroencephalography (EEG) recording (10–20 system) with inter-ictal discharges marked separately by an expert, (2) a full set of magnetic resonance imaging (MRI) scans for calculations of the realistic forward models, (3) structural placement of the epileptogenic zone, recognized by electrocorticography (ECoG) and post-surgical results, plotted on pre-surgical MRI scans in transverse, sagittal and coronal projections, (4) brief clinical description of each case. The main goal of this project is evaluation of possible improvements of localization of epileptic foci from the surface EEG recordings. These datasets offer a unique possibility for evaluating different EEG inverse solutions. We present preliminary results from a subset of these cases, including comparison of different schemes for the EEG inverse solution and preprocessing. We report also a finding which relates to the selective parametrization of single waveforms by multivariate matching pursuit, which is used in the preprocessing for the inverse solutions. It seems to offer a possibility of tracing the spatial evolution of seizures in time
Correction to: GloPL,a Global Data Base on Pollen Limitation of Plant Reproduction (Scientific Data, (2018), 5, (180249), 10.1038/sdata.2018.249)
J. H. Burns was omitted in error from the author list of the original version of this Data Descriptor. This omission has now been corrected in both the HTML and PDF versions
EEG windowed statistical wavelet scoring for evaluation and discrimination of muscular artifacts
EEG recordings are usually corrupted by spurious extra-cerebral artifacts,
which should be rejected or cleaned up by the practitioner. Since manual
screening of human EEGs is inherently error prone and might induce
experimental bias, automatic artifact detection is an issue of importance.
Automatic artifact detection is the best guarantee for objective and clean results.
We present a new approach, based on the time–frequency shape of muscular
artifacts, to achieve reliable and automatic scoring. The impact of muscular
activity on the signal can be evaluated using this methodology by placing
emphasis on the analysis of EEG activity. The method is used to discriminate
evoked potentials from several types of recorded muscular artifacts—with a
sensitivity of 98.8% and a specificity of 92.2%. Automatic cleaning ofEEGdata
are then successfully realized using this method, combined with independent
component analysis. The outcome of the automatic cleaning is then compared
with the Slepian multitaper spectrum based technique introduced by Delorme
et al (2007 Neuroimage 34 1443–9)
A half-site multimeric enzyme achieves its cooperativity without conformational changes
Cooperativity is a feature many multimeric proteins use to control activity. Here we show that the bacterial heptose isomerase GmhA displays homotropic positive and negative cooperativity among its four protomers. Most similar proteins achieve this through conformational changes: GmhA instead employs a delicate network of hydrogen bonds, and couples pairs of active sites controlled by a unique water channel. This network apparently raises the Lewis acidity of the catalytic zinc, thus increasing the activity at one active site at the cost of preventing substrate from adopting a reactive conformation at the paired negatively cooperative site – a “half-site” behavior. Our study establishes the principle that multimeric enzymes can exploit this cooperativity without conformational changes to maximize their catalytic power and control. More broadly, this subtlety by which enzymes regulate functions could be used to explore new inhibitor design strategies
Revealing Historic Invasion Patterns and Potential Invasion Sites for Two Non-Native Plant Species
The historical spatio-temporal distribution of invasive species is rarely documented, hampering efforts to understand invasion dynamics, especially at regional scales. Reconstructing historical invasions through use of herbarium records combined with spatial trend analysis and modeling can elucidate spreading patterns and identify susceptible habitats before invasion occurs. Two perennial species were chosen to contrast historic and potential phytogeographies: Japanese knotweed (Polygonum cuspidatum), introduced intentionally across the US; and mugwort (Artemisia vulgaris), introduced largely accidentally to coastal areas. Spatial analysis revealed that early in the invasion, both species have a stochastic distribution across the contiguous US, but east of the 90th meridian, which approximates the Mississippi River, quickly spread to adjacent counties in subsequent decades. In contrast, in locations west of the 90th meridian, many populations never spread outside the founding county, probably a result of encountering unfavorable environmental conditions. Regression analysis using variables categorized as environmental or anthropogenic accounted for 24% (Japanese knotweed) and 30% (mugwort) of the variation in the current distribution of each species. Results show very few counties with high habitat suitability (≥80%) remain un-invaded (5 for Japanese knotweed and 6 for mugwort), suggesting these perennials are reaching the limits of large-scale expansion. Despite differences in initial introduction loci and pathways, Japanese knotweed and mugwort demonstrate similar historic patterns of spread and show declining rates of regional expansion. Invasion mitigation efforts should be concentrated on areas identified as highly susceptible that border invaded regions, as both species demonstrate secondary expansion from introduction loci
High dispersal ability is related to fast life-history strategies
1. Seed dispersal is an essential, yet often overlooked process in plant ecology and evolution, affecting adaptation capacity, population persistence and invasiveness. A species’ ability to disperse is expected to covary with other life‐history traits to form dispersal syndromes. Dispersal might be linked to the rate of life history, fecundity or generation time, depending on the relative selection pressures of bet‐hedging, kin competition or maintaining gene flow. However, the linkage between dispersal and plant life‐history strategies remains unknown because it is difficult to observe, quantify and manipulate the influence of dispersal over large spatiotemporal scales.
2. We integrate datasets describing plant vital rates, dispersal and functional traits to incorporate dispersal explicitly into the rich spectra of plant life‐history strategies. For 141 plant species, we estimated dispersal ability by predicting maximum dispersal distances using allometric relationships based on growth form, dispersal mode, terminal velocity and seed mass. We derived life‐history traits from matrix population models parameterized with field data from the COMPADRE Plant Matrix Database. We analysed the covariation in dispersal ability and life‐history traits using multivariate techniques.
3. We found that three main axes of variation described plant dispersal syndromes: the fast‐slow life‐history continuum, the dispersal strategy axis and the reproductive strategy axis. On the dispersal strategy axis, species’ dispersal abilities were positively correlated with aspects of fast life histories. Species with a high net reproductive rate, a long window of reproduction, low likelihood of escaping senescence and low shrinkage tendencies disperse their seeds further. The overall phylogenetic signal in our multidimensional analyses was low (Pagel's λ < 0.24), implying a high degree of taxonomic generality in our findings.
4. Synthesis. Dispersal has been largely neglected in comparative demographic studies, despite its pivotal importance for populations. Our explicit incorporation of dispersal in a comparative life‐history framework provides key insights to bridge the gap between dispersal ecology and life‐history traits. Species with fast life‐history strategies disperse their seeds further than slow‐living plants, suggesting that longer dispersal distances may allow these species to take advantage of habitats varying unpredictably in space and time as a bet‐hedging strategy
Identifying source populations for the reintroduction of the Eurasian beaver, Castor fiber L. 1758, into Britain: evidence from ancient DNA
The file attached is the Published/publisher’s pdf version of the article
- …