River dolphin distribution in regulated river systems: implications for dry‐season flow regimes in the Gangetic basin

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DISAGGREGATED ANALYSIS OF FISH SUPPLY,DEMAND, AND TRADE IN ASIA: BASELINE MODEL AND ESTIMATION STRATEGY

ABSTRACT

Quantitative modeling of fish supply, demand and trade is a useful tool for analyzing recent structural changes, such as the rapid development of aquaculture. Existing models are, however, limited by their use of highly aggregated fish categories and assumed (rather than estimated) elasticities. This paper outlines an estimation strategy and a multiproduct equilibrium model for disaggregated analysis of fish supply, demand, and trade. The model is composed of a producer, consumer and trade core, and is specified to accommodate special features of the fish sector. The estimation and modeling strategy also address common data problems, such as heterogeneity of fish types, diversity of production categories, and so forth. The model has been applied to nine major fish producers in developing Asia.     

Fish to 2030: The Role and Opportunity for Aquaculture

Seafood sector can contribute to the global food supply in an important way, and provide an important source of animal protein. Based on observed regional trends in seafood production and consumption and using a global, partial-equilibrium, multi-market model, this study investigates what the global seafood market may look like in 2030. The model projects that the total fish supply will increase from 154 million tons in 2011 to 186 million tons in 2030, with aquaculture entirely responsible for the increase. The fastest aquaculture growth is expected for tilapia and shrimp, while the largest expansion is expected in India, Latin America and Caribbean and Southeast Asia. Fast-growing seafood demand in China and elsewhere represents a critical opportunity for global fisheries and aquaculture to improve their management and achieve sustainable seafood economy.     

Stability via asynchrony in Drosophila metapopulations with low migration rates

Very few experimental studies have examined how migration rate affects metapopulation dynamics and stability. We studied the dynamics of replicate laboratory metapopulations of Drosophila under different migration rates. Low migration stabilized metapopulation dynamics, while promoting unstable subpopulation dynamics, by inducing asynchrony among neighboring subpopulations. High migration synchronized subpopulation dynamics, thereby destabilizing the metapopulations. Contrary to some theoretical predictions, increased migration did not affect average population size. Simulations based on a simple non-species-specific population growth model captured most features of the data, which suggests that our results are generalizable.     

Mental workload associated with operating an agricultural sprayer: an empirical approach

Agricultural spraying involves two major tasks: guiding a sprayer in response to a GPS navigation device, and simultaneous monitoring of rear-attached booms under various illumination and terrain difficulty levels. The aim of the present study was to investigate the effect of illumination, task difficulty, and task level on the mental workload of an individual operating an agricultural sprayer in response to a commercial GPS lightbar, and to explore the sensitivity of the NASA-TLX and SSWAT subjective rating scales in discriminating the subjective experienced workload under various task, illumination, and difficulty levels. Mental workload was measured using performance measures (lateral root mean square error and reaction time), physiological measures (0.1 Hz power of HRV, latency of the P300 component of event-related potential, and eye-glance behavior), and two subjective rating scales (NASA-TLX and SSWAT). Sixteen male university students participated in this experiment, and a fixed-base high-fidelity agricultural tractor simulator was used to create a simulated spraying task. All performance measures, the P300 latency, and subjective rating scales showed a common trend that mental workload increased with the change in illumination from day to night, with task difficulty from low to high, and with task type from single to dual. The 0.1 Hz power of HRV contradicted the performance measures. Eye-glance data showed that under night illumination, participants spent more time looking at the lightbar for guidance information. A similar trend was observed with the change in task type from single to dual. Both subjective rating scales showed a common trend of increasing mental workload with the change in illumination, difficulty, and task levels. However, the SSWAT scale was more sensitive than the NASA-TLX scale. With the change in illumination, difficulty, and task levels, participants spent more mental resources to meet the increased task demand; hence, the illumination, task difficulty, and task level affected the mental workload of an agricultural sprayer operator operating a sprayer in response to a GPS lightbar.     

Rapid fabrication and optimization of silk fibers supported and stabilized MnO<Subscript>2</Subscript> catalysts

We report on the in situ synthesis and stabilization of manganese dioxide (MnO₂) onto four different silk yarns (mulberry, tasar, muga and eri silks). A new ultrasound-assisted procedure was used to reduce permanganate (MnO₄ ^?) and yielded MnO₂ nanoparticles (NPs) on/in the different silk fibers. Using a factorial design we assessed the influence of the silk type, manganese precursor concentration, sonication time, and temperature. The results indicated no measurable effect of the process parameters on the silk structures, but significant correlation with the rate of degradation of methylene blue (MB) and the fraction of permanganate consumed. Further optimization of the factorial model identified the optimal process conditions for each silks: mulberry (150 min sonication, 20 mM permanganate), eri (360 min, 10 mM), tasar (150 min, 10 mM) and Muga (20 min, 10 mM). The operational stability (successive catalysis) of the optimum hybrids showed good performance over 5 cycles and most importantly reduced direct dye absorption relatively to dye oxidation. Overall, we found that all silks could template the formation and stabilization of different MnO₂ polymorphs and yielded catalytic instead of stoichiometric hybrid fibers.     

Seedborne infection ofAscochyta rabiei in chickpea and its transmission to aerial plant parts

Ascochyta blight of chickpea (Cicer arietinum L.), caused byAscochyta rabiei (Pass.) Labrousse, was found to be both externally as well as internally seedborne in nature, with the external infection being predominant. The pathogen was located primarily on or in the seed coat and in very few cases penetrated into the cotyledons and rarely, to the embryo. Seedling infection resulted from both externally as well as internally seedborne inoculum. The mode of fungal transmission from seed to the foliar plant parts was strictly non-systemic in nature.     

Seroprevalence of bluetongue and presence of viral antigen and type-specific neutralizing antibodies in goats in Tripura,a state at Indo-Bangladesh border of northeastern India

Tropical Animal Health and Production - Bluetongue (BT) is a notifiable multiple species transboundary viral disease of domestic and wild ruminants. Though the disease is enzootic in India, little...     

From production to consumption: a case study of tilapia marketing systems in Bangladesh

In spite of the long history of tilapia, introduced to Bangladesh in 1954, its culture has yet to become well established because of socioeconomic, technological, institutional, and marketing constraints. Nevertheless, a considerable number of farmers are involved in tilapia farming in the Mymensingh area of north-central Bangladesh. Almost all the tilapias produced are marketed internally for domestic consumption. The marketing chain from farmers to consumers encompasses primary, wholesale, and retail markets. Although the tilapia marketing system is traditional, it plays a vital role in connecting producers with consumers and thus contributes significantly in the value-adding process. Evidence from this study suggests that tilapia marketing could play a greater role in increasing food supply. However, sustainable development of tilapia marketing is essential, if tilapia is to become a more important component of food supplies in the country.