The simultaneous use of ATVS and ATCM enables significant radiation dose reduction in abdominal and thoracic contrast-enhanced CT examinations compared with the use of ATCM alone.
In invasion ecology, potential impacts of aliens on native flora are still under debate. Our aim was to determine the pollinator mediated effects of both proximity and abundance of an alien species on the reproductive success of natives. We chose the highly invasive Impatiens glandulifera and two native species: Epilobium angustifolium and Aconitum napellus ssp. lusitanicum. These species share characteristics allowing for pollination interactions: similar biotopes, overlapping flowering periods and same main pollinators. The effects of abundance (5, 25 and 100 individuals) and proximity (0 and 15 m) of the alien on visitation rate, insect behaviour, pollen deposition and reproductive success of both natives were investigated during 2 flowering seasons. We used centred visitation rates as they can be directly interpreted as a positive or negative effect of the invasive.Both abundance and proximity of the alien increased bumblebee visitation rates to both natives. On the other hand, abundance of the exotic species had a slight negative effect on honeybee visits to natives while its proximity had no effect. The behaviour of bumblebees changed as visitors left significantly more often the native plants for I. glandulifera when its abundance increased. As a consequence of this “inconstancy”, bees deposited considerable quantities of alien pollen on native stigmas. Nevertheless, this interspecific pollen transfer did not decrease seed set in natives. Self-compatibility and high attractiveness of both native species probably alleviate the risk of altered pollinator services and reproductive success due to the invader in natural populations.
OBJECTIVEThe purpose of the present study was to prospectively quantify the normal
limits of brain perfusion using specific software in a group of asymptomatic
young volunteers submitted to single-photon emission tomography (SPECT) with
99mTc-ethyl cysteinate dimer (99mTc-ECD).METHODSWe used 15 MBq/kg of intravenous 99mTc-ECD in 30 healthy
volunteers submitted to brief neuropsychological tests and a clinical
questionnaire. These data were normalized relative to the cerebellum (Group
1) and to the brain cortex (Group 2). Statistical analysis was performed
with Student's t-test. The average radioactivity was 6.5 million
counts/study.RESULTSThe normalized (Group I) revealed an average value of 78.03%, with standard
deviation (SD) of 4.07. Two volunteers in this group had slightly greater
than two standard deviations from the mean. When we used (Group II), the
average value was 71.01%, with a SD of 4.66. We observed a difference
between groups of 9% (P<0.001).CONCLUSIONThe present study suggests normal cortical perfusional values for a group of
young asymptomatic volunteers, utilizing 99mTc-ECD. This allows
further quantification of neuro-SPECT data, specifically comparisons across
patient populations. Furthermore, this method represents a new tool that can
be used to further explore the field of neuroimaging, particularly
neuropsychiatry.
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