scholarly journals A novel personal ventilation strategy to circumvent aerosol transmission

2021 ◽  
Author(s):  
Tomoaki Yoshida ◽  
Eiji Shibata ◽  
Natsuki Ishida ◽  
Tomoya Nakatani
Keyword(s):  
Air Flow ◽  
Published Data ◽  
Temporal And Spatial Distribution ◽  
Cooling Fan ◽  
Model Aerosol ◽  
Model Condition ◽  
Personal Ventilation ◽  
Temporal And Spatial ◽  
Personal Cooling ◽  
Indoor Spaces

Abstract In the pandemic of COVID-19, a rigorous lockdown or social distancing will mitigate transmission, but some alternative strategy is needed especially for mass-gathering events. Given that the main path of transmission is through droplets or aerosols, a swift removal of them immediately after exhalation, which may attain “personal air zoning”, would be more effective and feasible than whole room ventilations. In the present study, an artificial fog was employed as a model aerosol to be exhaled and readily visualized on movies and quantified on dust indicators. The temporal and spatial distribution of this model microdroplet amounts corresponded reasonably well with previously published data, where talking air flow was quantified as a negative staining, in that it predominates below the mouth height rather than horizontal, and that it travels forward over 1.5 m in 30 sec. Under this model condition, nearly 99% of exhaled microdroplets could be efficiently blown up beyond the bystanders’ head heights, when a minimal air flow (2.5 m/s) was applied, using a typical personal cooling fan just below the chin. This swift upward removal of microdroplets would prevent bystanders’ immediate inhalation and provide sufficient probation periods for safe exhaustion from indoor spaces.

scholarly journals Measurement of spatial and temporal fine sediment dynamics in a small river

2011 ◽  
Vol 8 (6) ◽  
pp. 11315-11355 ◽  
Author(s):  
Y. Schindler Wildhaber ◽  
C. Michel ◽  
P. Burkhardt-Holm ◽  
D. Baenninger ◽  
C. Alewell
Keyword(s):  
Spatial Distribution ◽  
Water Level ◽  
Low Cost ◽  
Spatial Dynamics ◽  
Fine Sediment ◽  
Sediment Dynamics ◽  
Published Data ◽  
Temporal And Spatial Distribution ◽  
Time Period ◽  
Temporal And Spatial

Abstract. Empirical measurements on fine sediment dynamics, infiltration and accumulation have been conducted worldwide, but it is difficult to compare the results because the applied methods differ widely. We compared established methods to capture temporal and spatial dynamics of suspended sediment (SS), fine sediment infiltration and accumulation and tested them for their suitability in small, canalized rivers of the Swiss Plateau. Suitability was assessed by data comparison, relation to hydrological data and in the context of previously published data. SS were assessed by optical backscatter (OBS) sensors and SS samplers. The former exhibit a better temporal resolution but were associated with calibration problems. Due to the relatively low cost and easy mounting of SS samplers, they can provide a higher spatial distribution in the cross section. This results in a better correlation between sediment infiltration and SS assessed by SS samplers than with OBS sensors. Sediment infiltration baskets and bedload traps were able to resolve the temporal and spatial distribution of fine sediment infiltration. Data obtained by both methods were positively correlated with water level and SS. In contrast, accumulation baskets can not assess the temporal behavior of fine sediment but the accumulation over a certain time period. Results indicate that less fine sediment accumulated in upwelling zones and within areas of higher mean water level due to scouring of fine sediment. Even though there was an increase of SS and sediment assessed with the bedload traps from up- to downstream, less fine sediment accumulated downstream. This is probably also due to more scouring downstream.

scholarly journals Measurement of spatial and temporal fine sediment dynamics in a small river

2012 ◽  
Vol 16 (5) ◽  
pp. 1501-1515 ◽  
Author(s):  
Y. Schindler Wildhaber ◽  
C. Michel ◽  
P. Burkhardt-Holm ◽  
D. Bänninger ◽  
C. Alewell
Keyword(s):  
Spatial Distribution ◽  
Water Level ◽  
Low Cost ◽  
Spatial Dynamics ◽  
Fine Sediment ◽  
Sediment Dynamics ◽  
Published Data ◽  
Temporal And Spatial Distribution ◽  
Temporal Behaviour ◽  
Temporal And Spatial

Abstract. Empirical measurements on fine sediment dynamics and fine sediment infiltration and accumulation have been conducted worldwide, but it is difficult to compare the results because the applied methods differ widely. We compared common methods to capture temporal and spatial dynamics of suspended sediment (SS), fine sediment infiltration and accumulation and tested them for their suitability in a small, canalized river of the Swiss Plateau. Measurement suitability was assessed by data comparison, relation to hydrological data and in the context of previously published data. SS concentration and load were assessed by optical backscatter (OBS) sensors and SS samplers. The former exhibit a better temporal resolution, but were associated with calibration problems. Due to the relatively low cost and easy mounting of SS samplers, they can provide a higher spatial distribution in the river's cross section. The latter resulted in a better correlation between sediment infiltration and SS load assessed by SS samplers than SS concentrations measured with OBS sensors. Sediment infiltration baskets and bedload traps capture the temporal and spatial distribution of fine sediment infiltration. Data obtained by both methods were positively correlated with water level and SS. In contrast, accumulation baskets do not assess the temporal behaviour of fine sediment, but the net accumulation over a certain time period. Less fine sediment accumulated in upwelling zones and within areas of higher mean water level due to scouring of fine sediments. Even though SS and sediment infiltration assessed with the bedload traps increased from up- to downstream, less fine sediment accumulated downstream. This is probably also attributable to more scouring downstream.

scholarly journals Dog colour patterns explained by modular promoters of ancient canid origin

2021 ◽  
Author(s):  
Danika L. Bannasch ◽  
Christopher B. Kaelin ◽  
Anna Letko ◽  
Robert Loechel ◽  
Petra Hug ◽  
...  
Keyword(s):  
Colour Pattern ◽  
Hair Cycle ◽  
Temporal And Spatial Distribution ◽  
Multiple Alleles ◽  
Haplotype Combination ◽  
Regulatory Modules ◽  
Regulatory Module ◽  
Temporal And Spatial ◽  
Selection For ◽  
Colour Patterns

AbstractDistinctive colour patterns in dogs are an integral component of canine diversity. Colour pattern differences are thought to have arisen from mutation and artificial selection during and after domestication from wolves but important gaps remain in understanding how these patterns evolved and are genetically controlled. In other mammals, variation at the ASIP gene controls both the temporal and spatial distribution of yellow and black pigments. Here, we identify independent regulatory modules for ventral and hair cycle ASIP expression, and we characterize their action and evolutionary origin. Structural variants define multiple alleles for each regulatory module and are combined in different ways to explain five distinctive dog colour patterns. Phylogenetic analysis reveals that the haplotype combination for one of these patterns is shared with Arctic white wolves and that its hair cycle-specific module probably originated from an extinct canid that diverged from grey wolves more than 2 million years ago. Natural selection for a lighter coat during the Pleistocene provided the genetic framework for widespread colour variation in dogs and wolves.

scholarly journals Analysis of the Temporal and Spatial Characteristics of Material Cultural Heritage Driven by Big Data—Take Museum Relics as an Example

Information ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 153
Author(s):  
Penglong Li ◽  
Zuoqin Shi ◽  
Yi Ding ◽  
Ling Zhao ◽  
Zezhong Ma ◽  
...  
Keyword(s):  
Cultural Heritage ◽  
Life Cycles ◽  
Cultural Communication ◽  
Temporal And Spatial Distribution ◽  
State Administration ◽  
Cultural Relic ◽  
Temporal And Spatial ◽  
Temporal And Spatial Characteristics ◽  
And Migration ◽  
Cultural Relics

Museum cultural relics represent a special material cultural heritage, and modern interpretations of them are needed in current society. Based on the catalogue data of cultural relics published by the State Administration of Cultural Heritage, this paper analyzes the continuity and intermittentness of cultural relics in time series by using the method of continuity judgment of cultural relics, analyzes the aggregation and migration of cultural relics in space by using the method of spatial analysis, and then uses cosine similarity to explain the similarity distribution in space and time. The results show that the overall distribution of cultural relics exhibits the characteristics of class aggregation, dynasty aggregation and regional aggregation. From the perspective of a time scale, cultural relics have different “life cycles”, displaying continuity, intermittentness, and similarity. From the perspective of a spatial scale, the cultural relic distribution forms a small “cultural communication circle”, showing aggregation, migration, and similarity. The temporal and spatial distribution of cultural relics exhibited more similar characteristics among dynasties that were closer together than those that were far away.

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