scholarly journals Laser-induced fluorescence emission (LIFE) from Lake Fryxell (Antarctica) cryoconites

2010 ◽  
Vol 51 (56) ◽  
pp. 145-152 ◽  
Author(s):  
Birgit Sattler ◽  
Michael C. Storrie-Lombardi ◽  
Christine M. Foreman ◽  
Markus Tilg ◽  
Roland Psenner

AbstractLaser-induced fluorescence emission (LIFE) images were obtained in situ from a 27 cm long ice core at Lake Fryxell, Antarctica. The excitation was accomplished with a simple 532 nm green laser pen light, and the fluorescence images were captured with a small compact digital camera. The targets for the experiment were mm-scale cryoconite assemblages found in the ice covers of this perennially frozen Antarctic lake. The fluorescence response originates from photo-pigments in cyanobacteria-dominated cryoconite assemblages with phycoerythrin (PE) exhibiting the optimal target cross section. This inexpensive, low-mass, low-energy method avoids manipulation of the in situ habitat and individual target organisms and does not disturb the microbial community or the surrounding ice matrix. We establish the correlation between fluorescence intensity and PE concentration. We show that cryoconite fluorescence response does not appear to decrease with depth in the ice cover, in agreement with similar findings at Lake Untersee, a perennially ice-covered lake in Dronning Maud Land, Antarctica. Optical reflection and refraction events at the air/ice interface can complicate quantitative estimates of total pigment concentrations. Laser targeting of a single mm-scale cryoconite can result in multiple neighboring excitation events secondary to reflection and refraction phenomena in the multiple air/ice interface of the bubbles surrounding the primary target.

Author(s):  
Klemens Weisleitner ◽  
Lars Hunger ◽  
Christoph Kohstall ◽  
Albert Frisch ◽  
Michael C. Storrie-Lombardi ◽  
...  

2020 ◽  
Author(s):  
Pamela S. Rickly ◽  
Lu Xu ◽  
John D. Crounse ◽  
Paul O. Wennberg ◽  
Andrew W. Rollins

Abstract. This work describes improvements made to the in-situ laser induced fluorescence SO2 instrument as originally described in Rollins et al. (2016). We report measurements of the SO2 fluorescence emission spectrum. These measurements allow for the determination of the most appropriate bandpass filters to optimize the fluorescence signal while reducing the instrumental background. Because many aromatic species fluoresce in the same spectral region as SO2, fluorescence spectra were also measured for naphthalene and anisole to determine if ambient SO2 measurements may be biased in the presence of such species. In addition, the 216.9 nm laser linewidth was decreased in order to increase the online/offline signal ratio which in-turn increases the precision of the measurement. The effects of these improvements on the instrumental sensitivity were determined by analyzing the signal and background of the instrument using varying optical bandpass filter ranges and cell pressures and calculating the resulting limit of detection. As a result, we report an improvement to the instrumental sensitivity by as much as 50 %.


2019 ◽  
Author(s):  
Nikki Theofanopoulou ◽  
Katherine Isbister ◽  
Julian Edbrooke-Childs ◽  
Petr Slovák

BACKGROUND A common challenge within psychiatry and prevention science more broadly is the lack of effective, engaging, and scale-able mechanisms to deliver psycho-social interventions for children, especially beyond in-person therapeutic or school-based contexts. Although digital technology has the potential to address these issues, existing research on technology-enabled interventions for families remains limited. OBJECTIVE The aim of this pilot study was to examine the feasibility of in-situ deployments of a low-cost, bespoke prototype, which has been designed to support children’s in-the-moment emotion regulation efforts. This prototype instantiates a novel intervention model that aims to address the existing limitations by delivering the intervention through an interactive object (a ‘smart toy’) sent home with the child, without any prior training necessary for either the child or their carer. This pilot study examined (i) engagement and acceptability of the device in the homes during 1 week deployments; and (ii) qualitative indicators of emotion regulation effects, as reported by parents and children. METHODS In this qualitative study, ten families (altogether 11 children aged 6-10 years) were recruited from three under-privileged communities in the UK. The RA visited participants in their homes to give children the ‘smart toy’ and conduct a semi-structured interview with at least one parent from each family. Children were given the prototype, a discovery book, and a simple digital camera to keep at home for 7-8 days, after which we interviewed each child and their parent about their experience. Thematic analysis guided the identification and organisation of common themes and patterns across the dataset. In addition, the prototypes automatically logged every interaction with the toy throughout the week-long deployments. RESULTS Across all 10 families, parents and children reported that the ‘smart toy’ was incorporated into children’s emotion regulation practices and engaged with naturally in moments children wanted to relax or calm down. Data suggests that children interacted with the toy throughout the duration of the deployment, found the experience enjoyable, and all requested to keep the toy longer. Child emotional connection to the toy—caring for its ‘well-being’—appears to have driven this strong engagement. Parents reported satisfaction with and acceptability of the toy. CONCLUSIONS This is the first known study investigation of the use of object-enabled intervention delivery to support emotion regulation in-situ. The strong engagement and qualitative indications of effects are promising – children were able to use the prototype without any training and incorporated it into their emotion regulation practices during daily challenges. Future work is needed to extend this indicative data with efficacy studies examining the psychological efficacy of the proposed intervention. More broadly, our findings suggest the potential of a technology-enabled shift in how prevention interventions are designed and delivered: empowering children and parents through ‘child-led, situated interventions’, where participants learn through actionable support directly within family life, as opposed to didactic in-person workshops and a subsequent skills application.


Sensors ◽  
2009 ◽  
Vol 9 (7) ◽  
pp. 5825-5843 ◽  
Author(s):  
Lonneke Goddijn-Murphy ◽  
Damien Dailloux ◽  
Martin White ◽  
Dave Bowers

1998 ◽  
Vol 25 (2) ◽  
pp. 189 ◽  
Author(s):  
A. Thiele ◽  
G.H. Krause ◽  
K. Winter

Photoinhibition of photosynthesis was studied in situ in leaves of several species of plants growing in natural treefall gaps of a tropical lowland forest (Barro Colorado Island, Panama). Leaves showed several features typical of sun-acclimation: relatively high pools of total carotenoids and xanthophyll cycle pigments and high ratios of chlorophyll a to b. During 1–2 h periods of exposure to direct mid-day sun, all leaves experienced substantial photoinhibition as indicated by a marked decline in the ratio of variable to maximum chlorophyll a fluorescence emission, FV/FM, detected after 10 min of dark adaptation. After return to shade, these ‘dark-adapted’ FV/FM ratios increased with biphasic kinetics, similar to previous findings under controlled conditions in the laboratory. A phase lasting about 1 h accounted for most of the recovery of FV/FM and was followed by a slow phase which proceeded until sunset. The decline in FV/FM during photoinhibition and the fast phase of recovery correlated closely with the amounts of zeaxanthin in the leaves. Given the small portion of the second recovery phase which has previously been attributed to turnover of the D1 protein in Photosystem II, high xanthophyll cycle activity in these gap leaves is probably responsible for the major part of photoinhibition, providing an efficient energy dissipation pathway during periods of high sunlight exposure.


2003 ◽  
Vol 37 (24) ◽  
pp. 5732-5738 ◽  
Author(s):  
Ezra C. Wood ◽  
Paul J. Wooldridge ◽  
Jens H. Freese ◽  
Tim Albrecht ◽  
Ronald C. Cohen

2020 ◽  
Vol 8 (1) ◽  
pp. 53
Author(s):  
Thomas Oh ◽  
Jittiwat Sermsripong ◽  
Barry W. Hicks

Studies reporting quantitation and imaging of chlorophyll in corals using visible fluorescent emission in the red near 680 nm can suffer from competing emission from other red-emitting pigments. Here, we report a novel method of selectively imaging chlorophyll distributions in coral in situ using only the near infrared (NIR) fluorescence emission from chlorophyll. Commercially available equipment was assembled that allowed the sequential imaging of visible, visible-fluorescent, and NIR-fluorescent pigments on the same corals. The relative distributions of chlorophyll and fluorescent proteins (GFPs) were examined in numerous corals in the Caribbean Sea, the Egyptian Red Sea, the Indonesian Dampier Strait, and the Florida Keys. Below 2 m depth, solar induced NIR chlorophyll fluorescence can be imaged in daylight without external lighting, thus, it is much easier to do than visible fluorescence imaging done at night. The distributions of chlorophyll and GFPs are unique in every species examined, and while there are some tissues where both fluorophores are co-resident, often tissues are selectively enriched in only one of these fluorescent pigments. Although laboratory studies have clearly shown that GFPs can be photo-protective, their inability to prevent large scale bleaching events in situ may be due to their limited tissue distribution.


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