1,333 research outputs found
Plant Metabolomics Applications in the Brassicaceae: Added Value for Science and Industry
Crops from the family Brassicaceae represent a diverse and very interesting group of plants. In addition, their close relationship with the model plant, Arabidopsis thaliana, makes combined research on these species both scientifically valuable and of considerable commercial importance. In the post-genomics era, much effort is being placed on expanding our capacity to use advanced technologies such as proteomics and metabolomics, to broaden our knowledge of the molecular organization of plants and how genetic differences are translated into phenotypic ones. Metabolomics in particular is gaining much attention mainly due both to the comprehensiveness of the technology and also the potentially close relationship between biochemical composition (including human health-related phytochemicals) and phenotype. In this short review, a brief introduction to the main metabolomics technologies is given taking examples from research on the Brassicaceae for illustratio
Enhancement of deep epileptiform activity in the EEG via 3-D adaptive spatial filtering,
The detection of epileptiform discharges (EDâs) in the electroencephalogram (EEG) is an important component in the diagnosis of epilepsy. However, when the epileptogenic source is located deep in the brain, the EDâs at the scalp are often masked by more superficial, higher-amplitude EEG activity. A
noninvasive technique which uses an adaptive âbeamformerâ spatial filter has been investigated for the enhancement of signals from deep sources in the brain suspected of containing EDâs. A forward three-layer spherical model was used to relate a dipolar source to recorded signals to determine the beamformerâs spatial response constraints. The beamformer adapts, using the least-mean-squares (LMS) algorithm, to reduce signals from sources distant to some arbitrarily defined location in the brain. The beamformer produces three outputs, being the orthogonal components of the signal estimated to have arisen at or near the assumed location. Simulations were performed by using the same forward model
to superimpose realistic EDâs on normal EEG recordings. The simulations show the beamformerâs ability to enhance signals
emanating from deep foci by way of an enhancement ratio (ER), being the improvement in signal-to-noise ratio (SNR) to that observed at any of the scalp electrodes. The performance of the beamformer has been evaluated for 1) the number of scalp electrodes, 2) the recording montage, 3) dependence on the background
EEG, 4) dependence on magnitude, depth, and orientation of epileptogenic focus, and 5) sensitivity to inaccuracies in the estimated location of the focus. Results from the simulations show the beamformerâs performance
to be dependent on the number of electrodes and moderately sensitive to variations in the EEG background. Conversely, its performance appears to be largely independent of the amplitude and morphology of the ED. The dependence studies indicated that the beamformerâs performance was moderately dependent on eccentricity with the ER increasing as the dipolar source and the beamformer were moved from the center to the surface of the brain (1.51â2.26 for radial dipoles and 1.17â2.69 for tangential dipoles). The beamformer was also moderately dependent on variations in polar or azimuthal angle for radial and tangential dipoles. Higher ERâs tended to be seen for locations between electrode sites. The beamformer was more sensitive to inaccuracies in both polar and azimuthal location than depth of the dipolar source.
For polar locations, an ER > 1.0 was achieved when the beamformer was located within 25 of a radial dipole and 35 of a tangential dipole. Similarly, angular ranges of 37.5 and 45 , respectively, for inaccuracies in azimuthal locations. Preliminary results from real EEG records, comprising 12 definite or questionable
epileptiform events, from four patients, demonstrated the beamformerâs ability to enhance these events by a mean 100%
(52%â215%) for referential data and a mean 104% (50%â145%) for bipolar data
Spectroscopic Applications of the (p,pi-) Reaction
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
Proton Induced Pi- Production from 7-Li
This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit
Continuum Pion Production
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
Grassland biodiversity restoration increases resistance of carbon fluxes to drought
Evidence suggests that the restoration of plant diversity in grasslands not only brings benefits for biodiversity conservation, but also the delivery of ecosystem services. While biodiversity-function experiments show that greater plant diversity increases resistance of plant productivity to climate extremes, it is not known whether real-world management options for grassland restoration likewise stabilize ecosystem responses to extreme climate events. We used a long-term (23Â year) field experiment in northern England to test the hypothesis that management aimed at biodiversity restoration increases the resistance and recovery of ecosystem carbon (C) fluxes to short-term summer drought. This was tested by measuring plant, soil and microbial responses to a simulated drought in experimental grassland plots where fertilizer application and seed addition have been managed to enhance plant species diversity. The cessation of fertilizer application brought about small increases in plant species richness. Additionally, cessation of fertilizer application reduced overall plant productivity and promoted hemi-parasitic plants at the expense of grasses and forbs. Resistance of CO 2 fluxes to drought, measured as ecosystem respiration, was greater in non-fertilized plots, as lower plant biomass reduced water demand, likely aided by proportionally more hemi-parasitic plants further reducing plant biomass. Additionally, legumes increased under drought, thereby contributing to overall resistance of plant productivity. Recovery of soil microbial C and nitrogen was more rapid after rewetting than soil microbial community composition, irrespective of restoration treatment, suggesting high resilience of soil microbial communities to drought. Synthesis and applications. This study shows that while grassland diversity restoration management increases the resistance of carbon fluxes to drought, it also reduces agricultural yields, revealing a trade-off for land managers. Furthermore legumes, promoted through long-term restoration treatments, can help to maintain plant community productivity under drought by increasing their biomass. As such, grassland management strategies not only have consequences for ecosystem processes, but also the capacity to withstand extreme weather events
Measurements of (p,pi Ì) Reactions Near Zero Degrees
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
Large Transverse Momenta in Statistical Models of High Energy Interactions
The creation of particles with large transverse momenta in high energy
hadronic collisions is a long standing problem. The transition from small-
(soft) to hard- parton scattering `high-pt' events is rather smooth. In this
paper we apply the non-extensive statistical framework to calculate transverse
momentum distributions of long lived hadrons created at energies from low
(sqrt(s)~10 GeV) to the highest energies available in collider experiments
(sqrt(s)~2000 GeV). Satisfactory agreement with the experimental data is
achieved. The systematic increase of the non-extensivity parameter with energy
found can be understood as phenomenological evidence for the increased role of
long range correlations in the hadronization process.
Predictions concerning the rise of average transverse momenta up to the
highest cosmic ray energies are also given and discussed.Comment: 20 pages, 10 figure
Nonstationary Stochastic Resonance in a Single Neuron-Like System
Stochastic resonance holds much promise for the detection of weak signals in
the presence of relatively loud noise. Following the discovery of nondynamical
and of aperiodic stochastic resonance, it was recently shown that the
phenomenon can manifest itself even in the presence of nonstationary signals.
This was found in a composite system of differentiated trigger mechanisms
mounted in parallel, which suggests that it could be realized in some
elementary neural networks or nonlinear electronic circuits. Here, we find that
even an individual trigger system may be able to detect weak nonstationary
signals using stochastic resonance. The very simple modification to the trigger
mechanism that makes this possible is reminiscent of some aspects of actual
neuron physics. Stochastic resonance may thus become relevant to more types of
biological or electronic systems injected with an ever broader class of
realistic signals.Comment: Plain Latex, 7 figure
Emergence of phlebotomine sandflies (Diptera: Psychodidade) in non-flooded forest floor in Central Amazon, Brazil: a modified emergence trap model
Information concerning the potential natural breeding sites of phlebotomine sandflies are of high epidemiological importance. However, few studies have been conducted on the subject. This is due especially to the difficulties in finding as well as extracting immature sandflies that develop in the soil and organic matter of the forest floor. In the present study, a modified emergence trap model was tested in order to find potential breeding sites. This model was tested in the Pitinga Village, situated in the Presidente Figueredo municipality, in the State of Amazonas. Twenty-seven individuals belonging to nine species (Lutzomyia umbratilis,L. monstruosa,L. ayrozai,L. anduzei,L. trichopyga,L. davisi,L. geniculata,L. georgii e L. saulensis.) were collected. Lutzomyia umbratilis showed the highest number of individuals (37.1%) of all species captured in the area. The phlebotomine productivity was estimated as 2.2 sandflies per 100 mÂČ/day. September showed the highest density of individuals, with a productivity of 5.8.InformaçÔes acerca de potenciais criadouros naturais de flebotomĂneos sempre foram de fundamental interesse epidemiolĂłgico. Contudo, sĂŁo poucas as informaçÔes advindas dos diversos estudos realizados atĂ© o momento. Isto se deve principalmente Ă s dificuldades de localização e extração dos imaturos que se desenvolvem no solo e matĂ©ria orgĂąnica do chĂŁo de florestas. No presente estudo o modelo modificado de armadilha de emergĂȘncia foi testado na Vila do Pitinga, municĂpio de Presidente Figueiredo, Estado do Amazonas, a fim de localizar potenciais criadouros naturais. Vinte e sete indivĂduos de nove espĂ©cies (Lutzomyia umbratilis,L. monstruosa,L. ayrozai,L. anduzei,L. trichopyga,L. davisi,L. geniculata,L. georgii e L. saulensis) foram coletados. Lutzomyia umbratilis foi a espĂ©cie com maior nĂșmero de indivĂduos, 10, representando 37,1% do total. A produção de flebotomĂneos foi estimada em 2,2 flebotomĂneos por 100 mÂČ por dia. Em setembro, mĂȘs com maior nĂșmero de indivĂduos, esta produção foi de 5,8
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