Photoacoustics — A Novel Tool for the Study of Aquatic Photosynthesis

The photoacoustic method allows direct determination of the energy-storage efficiency of photosynthesis by relating the energy stored by it to the total light energy absorbed by the plant material (Canaani et al., 1988; Malkin & Cahen, 1979; Malkin et al., 1990). These authors applied the photoacoustic method to leaves in the gas phase, where brief pulses caused concomitant pulses of oxygen that caused a pressure transient detected by a microphone. This method is based on the conversion of absorbed light to heat. Depending on the efficiency of the photosynthetic system, a variable fraction of the absorbed light energy is stored, thereby affecting the heat evolved and the resulting photoacoustic signal. The higher the photosynthetic efficiency, the greater will be the difference between the stored energy with and without ongoing photosynthesis (Cha & Mauzerall, 1992). These authors collected microalgal cells onto a filter and studied them by an approach similar to that previously used with leaves. In both cases, the oxygen signal is combined with that of thermal expansion resulting from conversion of the fraction of the light energy in the pulse that is not stored by photochemistry

Spatio-temporal dynamics of the urban fringe landscapes

Study of the land-use/land cover (LULC) changes close to the boundary of the buildup area (urban fringe) provides deeper understanding of a land-use dynamics at different spatial and temporal scales. Few thoughts have given to the analysis of complicated spatial landscape at a fringe area. The aim of this paper is to resolve this bias by focusing on these interfaces. Results of this paper show that majority of new urban development appear inside the fringe area. Moreover, two different processes of urban dynamics- addition of small and emergence of large buildup patches- have been revealed

Photoacoustics: a novel application to the determination of photosynthetic efficiency in zooxanthellate hermatypes

We present here a novel application of photoacoustics to the monitoring and study of the physiological status of zooxanthellate corals. Until now, the method has only been applied in homogeneous phytoplankton cultures and field samples. Corals are among the world's most productive ecosystems because they host symbiotic dinoflagellates (zooxanthellae) that provide them with a large amount of photosynthates for their energy requirements. Coral reefs face unprecedented pressures on local, regional, and global scales due to climate change and anthropogenic disturbances. Responses to such stress are often a decrease in the photosynthetic efficiency of the symbiotic dinoflagellates, as well as bleaching, which involves the mass expulsion of these symbionts or loss of their pigments. Photosynthesis is a sensitive indicator of stress in plants and plays a central role in the nutrition of symbiotic invertebrates. Our aim was to examine the applicability of photoacoustics, developed by us for ecological work with phytoplankton, to the study of symbiotic dinoflagellates in situ. We have determined areal chlorophyll content and light energy storage efficiency with three zooxanthellate coelenterates, two corals and one hydrozoan, hosting symbiotic algae. We also present the effect of temperature elevation on the decrease in photosynthetic efficiency of the symbiotic coral Stylophora pistillata determined by photoacoustics. Our results demonstrate the potential, power, and convenience of photoacoustics in following bleaching-related changes in coral pigmentation, in the photosynthetic energy storage efficiency of corals, and in its usefulness in diagnosing its health in relation to environmental factors, in the example presented here, seawater warming

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)