Three-Wall Segment (TriSeg) Model Describing Mechanics and Hemodynamics of Ventricular Interaction

A mathematical model (TriSeg model) of ventricular mechanics incorporating mechanical interaction of the left and right ventricular free walls and the interventricular septum is presented. Global left and right ventricular pump mechanics were related to representative myofiber mechanics in the three ventricular walls, satisfying the principle of conservation of energy. The walls were mechanically coupled satisfying tensile force equilibrium in the junction. Wall sizes and masses were rendered by adaptation to normalize mechanical myofiber load to physiological standard levels. The TriSeg model was implemented in the previously published lumped closed-loop CircAdapt model of heart and circulation. Simulation results of cardiac mechanics and hemodynamics during normal ventricular loading, acute pulmonary hypertension, and chronic pulmonary hypertension (including load adaptation) agreed with clinical data as obtained in healthy volunteers and pulmonary hypertension patients. In chronic pulmonary hypertension, the model predicted right ventricular free wall hypertrophy, increased systolic pulmonary flow acceleration, and increased right ventricular isovolumic contraction and relaxation times. Furthermore, septal curvature decreased linearly with its transmural pressure difference. In conclusion, the TriSeg model enables realistic simulation of ventricular mechanics including interaction between left and right ventricular pump mechanics, dynamics of septal geometry, and myofiber mechanics in the three ventricular walls

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Not AvailableThis study assessed the vulnerability of 16 floodplain wetlands (beels) of the Lower Brahmaputra Valley, Assam, India, in relation to a range of natural and anthropogenic factors including climate change. The total water-spread area of the selected beels varied widely (8–50 ha), with 68.75% of the beels showing a reduction in water-spread area over the past 30 years. High levels of siltation and encroachment and detachment of marginal areas through the construction of roads were the major factors responsible for the reduction in the water-spread area of the beels. The reduction was observed to be in the range of over 33% in three beels (Raghunath Sora, Chulkani, and Dudua beel) to 83% in Bhoishpuri beel. In addition, one beel (Chulkani) experienced reduction in its deep pool area, which is an important wetland area that provides shelter to brood fishes during the dry season. Only 12.5% of the beels studied practiced enclosure (pen) culture for rearing fish. None practiced cage culture. Our study showed that only two beels (Bhoishpuri and Tariachora) were free from exotic fishes; the remaining surveyed beels reported exotic species such as, Cyprinus carpio (Common Carp), Ctenopharyngodon idella (Grass Carp), Hypophthalmichthys molitrix (Silver Carp), H. nobilis (Bighead Carp) and Piaractus brachypomus (Pacu). The prevalence of exotic fishes in the majority of the beels (due both to escape from nearby aquaculture ponds during floods and intentional stocking in certain beels) would have adversely affected the diversity of indigenous fishes in those wetlands. From discussion with the fishers, 50% of the beels surveyed experienced a reduction in the number of fish species from that recorded 10–20 years ago. In addition to climate change-related factors (e.g. abnormal rains, floods, or drought-like situations), other factors – both natural (e.g. hyper-nutrification) and anthropogenic (e.g. construction of roads, houses, and other structures) – also adversely affected the studied wetlands. To help cope with these factors and increase the adaptive capacity of fishers, four measures aimed at mitigation are suggested. These are: the practice of enclosure aquaculture in beels; the construction of floating macrophyte refuges (katal); deep pool refuges; and stock enhancement programmes with climate-resilient indigenous fishes.Not Availabl

Effect of extreme climatic events on fish seed production in Lower Brahamaputra Valley, Assam, India: Constraint analysis and adaptive strategies

Not AvailableThe climate of Brahmaputra valley (located in the North-eastern Indian state of Assam) witnesses considerable changes with sub-tropical rain-storm atmosphere and has four well-defined seasons (monsoon, post-monsoon, winter and pre-monsoon) in a year. The state is experiencing extreme climatic events like erratic rainfall patterns (causing abnormally high floods) and drought-like situations in recent years, which adversely affects fish seed production thereby affecting pond aquaculture and fisheries enhancements in open-waters of the region. The present paper describes the major constraints faced by fish seed producers of the region because of extreme climatic events (abnormally high floods and prolonged dry spells) based on field studies in 27 fish seed production farms (randomly selected) located in three districts of Lower Brahmaputra Valley Zone of Assam, India. Primary data on different aspects of constraints faced by the fish seed producers because of extreme climatic events were collected and analysed. Rank Based Quotient values were calculated, based on ranks given by the fish seed producers for each constraint to prioritize them. Dominant constraint related to abnormally high floods faced by the fish seed producers was ‘loss of brood stock’ (Rank based quotient = 99.1) whereas the least important constraint was ‘entry of weeds/macrophytes’ during floods (Rank Based Quotient = 25.5). Constraints related to drought-like situations ranged from the least important ones like ‘low milt production of male brood fishes’ that had the lowest value (12.5) to the over-arching constraint of ‘inadequate water depth in fish ponds’ during pre-monsoon and prolonged dry spells (Rank Based Quotient = 100.0). Adaptive strategies developed by fish seed producers of the study region to overcome the major constraints have been outlined in the paper. The need for developing improved risk management at macro-level through appropriate policy support to fish seed producers in the fish-deficit region and suggested policy support measures for ensuring sustainability are discussed.Not Availabl

Social media enables people-centric climate action in the hard-to-decarbonise building sector

Funder: Laudes FoundationFunder: Keynes FundFunder: Quadrature Climate FoundationFunder: UK Space Agency; doi: http://dx.doi.org/10.13039/100011690Funder: Resnick Sustainability Institute for Science, Energy and Sustainability, California Institute of Technology; doi: http://dx.doi.org/10.13039/100007287The building and construction sector accounts for around 39% of global carbon dioxide emissions and remains a hard-to-abate sector. We use a data-driven analysis of global high-level climate action on emissions reduction in the building sector using 256,717 English-language tweets across a 13-year time frame (2009–2021). Using natural language processing and network analysis, we show that public sentiments and emotions on social media are reactive to these climate policy actions. Between 2009–2012, discussions around green building-led emission reduction efforts were highly influential in shaping the online public perceptions of climate action. From 2013 to 2016, communication around low-carbon construction and energy efficiency significantly influenced the online narrative. More significant interactions on net-zero transition, climate tech, circular economy, mass timber housing and climate justice in 2017–2021 shaped the online climate action discourse. We find positive sentiments are more prominent and recurrent and comprise a larger share of the social media conversation. However, we also see a rise in negative sentiment by 30–40% following popular policy events like the IPCC report launches, the Paris Agreement and the EU Green Deal. With greater online engagement and information diffusion, social and environmental justice topics emerge in the online discourse. Continuing such shifts in online climate discourse is pivotal to a more just and people-centric transition in such hard-to-decarbonise sectors.RD acknowledges support from the Cambridge Zero and Quadrature Climate Foundation, Laudes Foundation, the Bill and Melinda Gates Foundation [OPP1144], Cambridge Judge Business School Small Grant (2020–21), the Keynes Fund 2021–22 [JHVH] and the Alan Turing Institute’s Postdoctoral Enrichment Award [G116750]. Caltech’s Resnick Sustainability Institute supports RMA’s work. RB’s work is supported by the UK Space Agency NSIP Award (2021–22)

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Not AvailableKeeping the importance and search for unconventional feed resources and/or standardizing their level of incorporation in mind, we incorporated dry-powdered water hyacinth (Eichhornia crassipes) meal in feeds and studied its effect on growth and digestibility in Labeo rohita fingerlings. Five feeds with 30 % crude protein level were formulated using Eichhornia meal (EM) at 0 (control), 5 (EMF1), 10 (EMF2), 15 (EMF3) or 20 % (EMF4) of the diet replacing rice bran by equal proportions. Three hundred fingerlings (7.40 ± 0.05 cm; 5.27 ± 0.12 g) were distributed into fifteen tanks (200 l capacity) and fed the experimental diets for 60 days. In the last 30 days, digestibility studies were conducted using 0.5 % chromic oxide as an external marker in feed. At 10 % inclusion of EM, the experimental fish showed the highest weight gain percent (WG%), specific growth rate (SGR), protein efficiency ratio and apparent net protein utilization with lowest feed conversion ratio. Whereas the growth performance at 15 % inclusion level was comparable with the control and further increase to 20 % level of EM showed reduced growth responses but the feed was fairly palatable to the fish. Lower digestibility was also observed in EMF4 group. It is concluded that EM can be included at 15 % level in the feed of L. rohita fingerlings without adversely affecting the growth, dry matter and nutrient digestibility. However, economic feasibility of this feedstuff needs to be analyzed to see whether the reduced cost of diets would compensate for the reduced performance of fish at higher inclusion levels.Not Availabl

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Not AvailableIndian minor carp Labeo bata fingerlings were reared in square shaped cages at different numbers to evaluate the effect of stocking density on growth, production and economics. Fifteen cages (5 × 5 × 2 m each) were installed in deeper areas (6–8 m) of Samaguri beel (a seasonally-flooded floodplain wetland) of Assam, India. The cages were stocked with L. bata (mean length 11.93 ± 0.20 cm; mean weight 13.05 ± 0.77 g) at five different stocking densities of 10 (SD10), 20 (SD20), 30 (SD30), 40 (SD40) and 50 (SD50) fingerlings m−3 in triplicates. Fish were fed with floating pellets containing 32% CP at 3–5% body weight twice-a-day for six months. Density-dependent growth was evident from the results as growth of fish decreased with increasing stocking densities; the specific growth rate of the fish at SD10, SD20, SD30, SD40 and SD50 were 1.03 ± 0.02, 0.88 ± 0.01, 0.84 ± 0.02, 0.67 ± 0.02 and 0.52 ± 0.01 with corresponding weight gain percent of 533.3 ± 13.41, 385.8 ± 10.73, 353.3 ± 14.17, 232.2 ± 8.08 and 155.9 ± 5.38, respectively. However, the highest net yield of fish was achieved at SD30 (50.8 kg cage−1), which was significantly higher than other stocking densities. Also, economic analysis demonstrated highest benefit-cost (B:C) ratio at 30 fish m−3 (1.44). Results indicated decreased fish yield at lower densities though the individual growth rate of fish was higher. On the other hand, fingerling stocking more than 30 fish m−3 was uneconomical because of lower individual growth rate. Hence, a stocking density of 30 fish m−3 could be considered as optimum for production of L. bata table fish in cages. The study generated new and critical information on species diversification in cage aquaculture for tropical floodplain wetlands.Not Availabl

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Not AvailableCatla (Catla catla) is a one of the most harvested Indian major carps and is widely cultured fish species in Indian subcontinent. In the present study, genetic variability between hatchery and wild stocks of Catla was surveyed using sequence data of mitochondrial DNA of partial 307 bp of cytochrome b region. A total of 174 Catla individuals were examined from three different river basins and hatcheries. Significant genetic heterogeneity was observed for the sequence data (FST = 0.308, p ≤ 0.001). However, analysis of molecular variance (AMOVA) resulted in insignificant genetic differentiation among the samples of three rivers and culture zones (FCT = −0.10, p = 0.44). The result suggested a significant genetic variation within different riverine system, low genetic differentiation among samples from river basins and a lack of genetic variation in hatchery populations.Not Availabl