scholarly journals Review of "Seasonal timeline for snow-covered sea ice processes in Nunavik's Deception Bay from TerraSAR-X and time-lapse photography" by Dufour-Beauséjour et al.

2019 ◽  
Author(s):  
Anonymous
2019 ◽  
Author(s):  
Sophie Dufour-Beauséjour ◽  
Anna Wendleder ◽  
Yves Gauthier ◽  
Monique Bernier ◽  
Jimmy Poulin ◽  
...  

2020 ◽  
Vol 14 (5) ◽  
pp. 1595-1609 ◽  
Author(s):  
Sophie Dufour-Beauséjour ◽  
Anna Wendleder ◽  
Yves Gauthier ◽  
Monique Bernier ◽  
Jimmy Poulin ◽  
...  

Abstract. This article presents a case study for the combined use of TerraSAR-X and time-lapse photography time series in order to monitor seasonal sea ice processes in Nunavik's Deception Bay. This area is at the confluence of land use by local Inuit, ice-breaking transport by the mining industry, and climate change. Indeed, Inuit have reported greater interannual variability in seasonal sea ice conditions, including later freeze-up and earlier breakup. Time series covering 2015 to 2018 were acquired for each data source: TerraSAR-X images were acquired every 11 d, and photographs were acquired hourly during the day. We used the combination of the two time series to document spatiotemporal aspects of freeze-up and breakup processes. We also report new X-band backscattering values over newly formed sea ice types. The TerraSAR-X time series further show potential for melt and pond onset.


2019 ◽  
Author(s):  
Sophie Dufour-Beauséjour ◽  
Anna Wendleder ◽  
Yves Gauthier ◽  
Monique Bernier ◽  
Jimmy Poulin ◽  
...  

Abstract. Inuit have reported greater inter-annual variability in seasonal sea ice conditions. For Deception Bay (Nunavik), an area prized for seal and caribou hunting, an increase in solid precipitation and a shorter snow cover period is expected in the near future. In this context, and considering ice-breaking transport in the fjord by mining companies, we monitored sea ice in the area for three seasons of ice between 2015 and 2018. This article presents a case study for the combined use of TerraSAR- X and time-lapse photography time-series in order to monitor snow-covered sea ice seasonal processes. The X-band median backscattering is shown to reproduce the seasonal evolution expected from C-band data. Two different freeze-up and breakup processes are characterized. New X-band backscattering values from newly formed ice types are reported. The monitoring approach presented in this article has the potential to be applied in other remote locations, and processes outlined here may inform our understanding of other fjords or bays where ice-breakers transit.


1953 ◽  
Vol s3-94 (28) ◽  
pp. 369-379
Author(s):  
M. M. SWANN

1. Developing eggs of the sea-urchin Psammechinus miliaris were subjected to carbon monoxide inhibition, which was controlled by changing from green to white light. The behaviour of the eggs was recorded by time-lapse photography. 2. If inhibition is applied before the eggs enter mitosis, their first cleavage is delayed by a time which is roughly equal to the period of the inhibition. 3. If the inhibition is applied when the cells have already entered mitosis, they complete mitosis and cleave with little or no delay, but their second cleavage is delayed by a time which is roughly equal to the period of the inhibition. 4. It is suggested that the necessary energy for the second mitosis and cleavage is being stored up during the first mitosis and cleavage, and that this energy store operates like a reservoir which is continually being filled but siphons out when it is full. Once the energy has siphoned out, it carries mitosis and cleavage through, even though the reservoir is not filling up because of carbon monoxide inhibition.


1992 ◽  
Vol 38 (129) ◽  
pp. 257-265 ◽  
Author(s):  
W.D. Harrison ◽  
K.A. Echelmeyer ◽  
D.M. Cosgrove ◽  
C. F. Raymond

AbstractTwo practical problems in the use of time-lapse photography for the measurement of speed were encountered during the recent surge of West Fork Glacier in the central Alaska Range, Alaska, U.S.A. The first is severe rotational camera instability; we show how natural, unsurveyed features on the valley wall can be used to make the necessary corrections. The second problem is the computation of absolute speed when many different, unsurveyed glacier-surface features are used as targets. We give a method for connecting the data obtained from different targets, and for determining the scale using limited information obtained by surveying. Severe systematic errors can occur unless the angle between the axis of the lens and the direction of horizontal motion is determined.


2001 ◽  
Vol 12 (8) ◽  
pp. 2245-2256 ◽  
Author(s):  
Elena Smirnova ◽  
Lorena Griparic ◽  
Dixie-Lee Shurland ◽  
Alexander M. van der Bliek

Mutations in the human dynamin-related protein Drp1 cause mitochondria to form perinuclear clusters. We show here that these mitochondrial clusters consist of highly interconnected mitochondrial tubules. The increased connectivity between mitochondria indicates that the balance between mitochondrial division and fusion is shifted toward fusion. Such a shift is consistent with a block in mitochondrial division. Immunofluorescence and subcellular fractionation show that endogenous Drp1 is localized to mitochondria, which is also consistent with a role in mitochondrial division. A direct role in mitochondrial division is suggested by time-lapse photography of transfected cells, in which green fluorescent protein fused to Drp1 is concentrated in spots that mark actual mitochondrial division events. We find that purified human Drp1 can self-assemble into multimeric ring-like structures with dimensions similar to those of dynamin multimers. The structural and functional similarities between dynamin and Drp1 suggest that Drp1 wraps around the constriction points of dividing mitochondria, analogous to dynamin collars at the necks of budding vesicles. We conclude that Drp1 contributes to mitochondrial division in mammalian cells.


Sign in / Sign up

Export Citation Format

Share Document