5,382 research outputs found
A Taxonomic Study of Variation in Leptochloa Fascicularis (LAM.) Gray in the Central Great Plains
The morphology of Leptochloa fascicularis (Lam.) Gray (Poaceae) was studied in 25 locations in eastern and central Nebraska to determine if this grass was separable into two distinct taxa as suggested in several recent sources. Field collections were supplemented with herbarium specimens from other parts of the Central Great Plains. Glume and lemma lengths, the characters used in published keys, provided no separations useful in dividing the material into two species or varieties. However, individual local populations exhibited significant differences from each other in these characters. Such local differences appear to be reasonable given the high degree of inbreeding that appears to be prevalent at most locations
A taxonomic study of variation in Leptochloa fascicularis in the central Great Plains.
Morphology of Leptochloa fascicularls (Lam.) Gray (Poaceae) was studied in 25 locations in eastern and central Nebraska to determine if this grass was separable into two distinct taxa as suggested in several recent sources. Field collections were supplemented with herbarium samples from the University of Kansas. Glume and lemma lengths, the characters used in published keys, provided no separations useful in dividing the material into two species or varieties. However, individual local populations exhibited significant differences from each other in these characters. Such local differences appear to be reasonable given the high degree of inbreeding that is to be expected with cleistogamous reproduction such as that predominating at most of the more xeric field locations. Chasmogamy was confined to moist habitats
How distant? An experimental analysis of studentsâ COVID-19 exposure and physical distancing in university buildings
University buildings are significant closed built environments for COVID-19
spreading. As universities prepare to re-start in-class activities, students'
adherence to physical distancing requirements is a priority topic. While
physical distancing in classrooms can be easily managed, the movement of
students inside common spaces can pose higher risks due to individuals'
proximity. This paper provides an experimental analysis of unidirectional
student flow inside a case-study university building, by investigating
students' movements and grouping behaviour according to physical distancing
requirements. Results show general adherence with the minimum required physical
distancing guidance, but some spaces, such as corridors, pose higher exposure
than doorways. Their width, in combination with group behaviour, affects the
students' capacity to keep the recommended distance. Furthermore, students
report higher perceived vulnerability while moving along corridors.
Evidence-based results can support decision-makers in understanding
individuals' exposure in universities and researchers in developing behavioural
models in preparation of future outbreaks and pandemics.Comment: 22 pages, 5 figures, 1 table. Currently submitted to "International
Journal of Disaster Risk Reduction
How distant? An experimental analysis of studentsâ COVID-19 exposure and physical distancing in university buildings
Closed university buildings proved to be one of the main hot spots for virus transmission during pandemics. As shown during the COVID-19 pandemic, physical distancing is one of the most effective measures to limit such transmission. As universities prepare to manage in-class activities, studentsâ adherence to physical distancing requirements is a priority topic. Unfortunately, while physical distancing in classrooms can be easily managed, the movement of students inside common spaces can pose high risk of close proximity. This paper provides an experimental analysis of unidirectional student movement inside a case-study university building to investigate how physical distancing requirements impact student movement and grouping behaviour. Results show general adherence with the minimum required physical distancing guidance, but spaces such as corridors pose higher risk of exposure than doorways. Doorway width, in combination with group behaviour, affect the students' capacity to keep the recommended physical distance. Furthermore, questionnaire results show that students report higher perceived vulnerability while moving along corridors. Evidence-based results can support decision-makers in understanding individualsâ exposure to COVID-19 in universities and researchers in developing behavioural models in preparation of future outbreaks and pandemics
Fermion propagator for QED_3 in the IR domain
We evaluate the fermion propagator in parity-conserving QED_3 with N
flavours, in the context of an IR domain approximation. This provides results
which are non-perturbative in the loopwise expansion sense. We include
fermion-loop effects, and show that they are relevant to the chiral symmetry
breaking phenomenon, that can be understood in this context.Comment: 11 pages, LaTeX; typo corrected in Eq.3
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