326 research outputs found
Campylobacter spp., Enterococcus spp., Escherichia coli, Salmonella spp., Yersinia spp., and Cryptosporidium oocysts in semi-domesticated reindeer (Rangifer tarandus tarandus) in Northern Finland and Norway
The specific aim of this study was to assess the faecal shedding of zoonotic enteropathogens by semi-domesticated reindeer (Rangifer tarandus tarandus) to deduce the potential risk to human health through modern reindeer herding. In total, 2,243 faecal samples of reindeer from northern regions of Finland and Norway were examined for potentially enteropathogenic bacteria (Campylobacter species, Enterococcus species, Escherichia coli, Salmonella species and Yersinia species) and parasites (Cryptosporidium species) in accordance with standard procedures. Escherichia coli were isolated in 94.7%, Enterococcus species in 92.9%, Yersinia species in 4.8% of the samples and Campylobacter species in one sample only (0.04%). Analysis for virulence factors in E. coli and Yersinia species revealed no pathogenic strains. Neither Salmonella species nor Cryptosporidium oocysts were detected. The public health risk due to reindeer husbandry concerning zoonotic diseases included in this study has to be considered as very low at present but a putative epidemiological threat may arise when herding conditions are changed with respect to intensification and crowding
Luminescence tuning of MOFs via ligand to metal and metal to metal energy transfer by co-doping of 2∞[Gd2Cl6(bipy)3]*2bipy with europium and terbium
The series of anhydrous lanthanide chlorides LnCl3, Ln=Pr–Tb, and 4,4'-bipyridine (bipy) constitute isotypic MOFs of the formula 2∞[Ln2Cl6(bipy)3]*2bipy. The europium and terbium containing compounds both exhibit luminescence of the referring trivalent lanthanide ions, giving a red luminescence for Eu3+ and a green luminescence for Tb3+ triggered by an efficient antenna effect of the 4,4'-bipyridine linkers. Mixing of different lanthanides in one MOF structure was undertaken to investigate the potential of this MOF system for colour tuning of the luminescence. Based on the gadolinium containing compound, co-doping with different amounts of europium and terbium proves successful and yields solid solutions of the formula 2∞[Gd2-x-yEuxTbyCl6(bipy)3]*2bipy (1–8), 0≤x, y≤0.5. The series of MOFs exhibits the opportunity of tuning the emission colour in-between green and red. Depending on the atomic ratio Gd:Eu:Tb, the yellow region was covered for the first time for an oxygen/carboxylate-free MOF system. In addition to a ligand to metal energy transfer (LMET) from the lowest ligand-centered triplet state of 4,4'-bipyridine, a metal to metal energy transfer (MMET) between 4f-levels from Tb3+ to Eu3+ is as well vital for the emission colour. However, no involvement of Gd3+ in energy transfers is observed rendering it a suitable host lattice ion and connectivity centre for diluting the other two rare earth ions in the solid state. The materials retain their luminescence during activation of the MOFs for microporosity
Multi-Sensor Field Studies of Lightning and Implications for MTG-LI
Future geostationary satellite systems will offer a variety of improved observing capabilities which will be
extremely useful for many applications like numerical weather forecasting, nowcasting of severe weather,
climate research or hydrology. The planning for MTG (Meteosat Third Generation) includes an optical
lightning imager (LI) as part of the payload. One requirement for a proper interpretation of these optical
data is a better understanding of what components of a flash are to be seen from space and how these
observations relate to ground based radio frequency observations. Therefore, the objectives of the present
study concern the improvement of the understanding of the complex lightning process which then enables
a proper interpretation of the optical data.
For assessing the future performances and benefits of a geostationary lightning sensor this study takes
advantage of the comprehensive lightning data sets obtained from the recent CHUVA field experiment
performed in Brazil. (CHUVA - Cloud processes of tHe main precipitation systems in Brazil: A contribUtion
to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement)). During the rainy season
of 2011-2012 a large number of ground based lightning detection systems was set up in the Sao Paulo
area in Brazil. In the present study we look at the detailed radio frequency (RF) based observation from
LINET (Lightning detection network operated by DLR, nowcast and USP) and observing strokes in the
VLF/LF (very low and low frequency) range, the LMA (Lightning mapping array) from NASA observing RF
sources in the VHF (very high frequency) range and the TRMM-LIS (Tropical Rainfall Measuring
Mission-Lightning Imaging Sensor) optical space borne lightning imager. The LIS is used as a reference
instrument for the future MTG-LI sensor as well as for the corresponding GLM sensor (Geostationary
Lightning Mapper) on GOES-R. Thus it is possible to study the relations between the RF and optical
signals from lightning in detail and to assess the performance of the future geostationary observations from
a set of proxy satellite data generated from the ground based observations.
In confirmation of previous studies, it was found that often a direct temporal coincidence of RF
signals (LINET strokes) and optical pulses (LIS groups) exists. The short baseline configuration
of LINET allowed to observe the strokes mapping the flash branches similar to LMA, but by
locating the limited number of strong cloud strokes rather than a large number of weak source
points from leader steps. An initial breakdown phase of vertically propagating sources can often
be found in LINET and LMA data. The higher level LINET and LMA signals have higher
probability to be optically detected. Lower level LINET and LMA signals are optically detected
from above in case of missing high level precipitation as inferred from radar observations
provided by USP. The new comprehensive data set allows for constructing proxy data for the
future geostationary lightning mappers
HD-EEG Based Classification of Motor-Imagery Related Activity in Patients With Spinal Cord Injury
Brain computer interfaces (BCIs) are thought to revolutionize rehabilitation after SCI, e.g., by controlling neuroprostheses, exoskeletons, functional electrical stimulation, or a combination of these components. However, most BCI research was performed in healthy volunteers and it is unknown whether these results can be translated to patients with spinal cord injury because of neuroplasticity. We sought to examine whether high-density EEG (HD-EEG) could improve the performance of motor-imagery classification in patients with SCI. We recorded HD-EEG with 256 channels in 22 healthy controls and 7 patients with 14 recordings (4 patients had more than one recording) in an event related design. Participants were instructed acoustically to either imagine, execute, or observe foot and hand movements, or to rest. We calculated Fast Fourier Transform (FFT) and full frequency directed transfer function (ffDTF) for each condition and classified conditions pairwise with support vector machines when using only 2 channels over the sensorimotor area, full 10-20 montage, high-density montage of the sensorimotor cortex, and full HD-montage. Classification accuracies were comparable between patients and controls, with an advantage for controls for classifications that involved the foot movement condition. Full montages led to better results for both groups (p < 0.001), and classification accuracies were higher for FFT than for ffDTF (p < 0.001), for which the feature vector might be too long. However, full-montage 10–20 montage was comparable to high-density configurations. Motor-imagery driven control of neuroprostheses or BCI systems may perform as well in patients as in healthy volunteers with adequate technical configuration. We suggest the use of a whole-head montage and analysis of a broad frequency range
Chaos in Axially Symmetric Potentials with Octupole Deformation
Classical and quantum mechanical results are reported for the single particle
motion in a harmonic oscillator potential which is characterized by a
quadrupole deformation and an additional octupole deformation. The chaotic
character of the motion is srongly dependent on the quadrupole deformation in
that for a prolate deformation virtually no chaos is discernible while for the
oblate case the motion shows strong chaos when the octupole term is turned on.Comment: 6 pages LaTex plus 4 figures available by contacting the authors
directly, published in PHYS.REV.LETT. 72(1994) 235
Testing mean differences among groups : multivariate and repeated measures analysis with minimal assumptions
To date, there is a lack of satisfactory inferential techniques for the analysis of multivariate data in factorial designs, when only minimal assumptions on the data can be made. Presently available methods are limited to very particular study designs or assume either multivariate normality or equal covariance matrices across groups, or they do not allow for an assessment of the interaction effects across within-subjects and between-subjects variables. We propose and methodologically validate a parametric bootstrap approach that does not suffer from any of the above limitations, and thus provides a rather general and comprehensive methodological route to inference for multivariate and repeated measures data. As an example application, we consider data from two different Alzheimers disease (AD) examination modalities that may be used for precise and early diagnosis, namely, single-photon emission computed tomography (SPECT) and electroencephalogram (EEG). These data violate the assumptions of classical multivariate methods, and indeed classical methods would not have yielded the same conclusions with regards to some of the factors involved.(VLID)250099
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