Responsible shrimp farming in vietnam: call for promoting and strenthening community based management approaches

Shrimp farming has been developing fast in Vietnam recently and is facing a number of challenges. These include environmental and socio-economic impacts, volatile international markets and current anti-dumping issues. This paper provides and analytical overview of major problems faced by the industry in Vietnam based on a literature review and experience gained under the UNDP-funded project VIE/97/030 "Environmental management in coastal aquaculture". The dominant characteristic of shrimp farming is its small-scale nature, based mainly on individual households. Development of shrimp farming has occurred through unplanned expansion in terms of number of farms, households, farming area, and - more recently - farming intensification. Traditional practices met constraints in meeting product quality standards in domestic and foreign markets. Demonstration under the project revealed that community-based management is an important way to bring farmers together to adopt responsible farming practices, and improve standards for quality shrimp production. Factors contributing to success of the management approach include: (1) farming communities' willingness to cooperate and provide labour; (2) development of management plans reflecting the practical needs of and benefits for the community; (3) building the capacity of key members; (4) integrating community activities into the state management network. Shrimp farming is very important to Vietnam. For responsible development we recommend that the government should promote and strengthen community-based management approaches. A legal policy document for community-based shrimp farmer management should be developed in order to provide specific guidelines for and delegate rights to local authorities and farmers.Keywords: VIE/97/030 project, Aquaculture Economics and Management, Shrimp farming, Vietnam, Fisheries Economics, Community based management, Responsible developmentKeywords: VIE/97/030 project, Aquaculture Economics and Management, Shrimp farming, Vietnam, Fisheries Economics, Community based management, Responsible developmen

Ownership Characteristics of Heir Property in a Black Belt County: A Quantitative Approach

The existing literature identifies heir property, land held communally by heirs of someone who has died without a will, as a primary cause of land loss among African Americans and a major factor contributing to persistent poverty in the South’s demographically-defined Black Belt. Despite the importance of this form of property, little systematic research has been done to quantify the extent of heir property or the potential wealth tied up in clouded titles. This study documents the presence of more than 1,500 heir property parcels in one Alabama Black Belt county (Macon) and describes the methodological challenges involved in such research. Our analysis identified distinctive characteristics of and significant relationships between a set of key ownership variables (taxpayer location, size and value of land, structural improvements, and municipal incorporation). We argue the need to document the extent and consequences of heir property to spur action by legislators, Extension Systems across the region, and pro-bono attorneys, among others, to address the personal and economic costs associated with this form of insecure ownership

DẪN LIỆU BƯỚC ĐẦU VỀ TÍNH CHẤT ĐỊA LÝ ĐỘNG VẬT ỐC NƯỚC NGỌT NỘI ĐỊA TẠI THỪA THIÊN HUẾ

The survey and sampling were conducted in Thua Thien Hue Province from May 2018 to July 2020. Initial remarks are made on the zoogeography of inland freshwater snails in Thua Thien Hue. In which, species with Indian-Malaysian characteristics are dominant (8 species; 40%), followed by widespread species (6 species; 30%), species with Chinese characteristics are less diverse (4 species; 20%) and Vietnamese endemic species are the least diverse (2 species; 10%).Khảo sát và thu mẫu ốc nước ngọt nội địa tại Thừa Thiên Huế được tiến hành từ tháng 5/2018 - 7/2020. Kết quả đã đưa ra nhận xét bước đầu về địa lý động vật ốc ở nước ngọt nội địa tại Thừa Thiên Huế. Trong đó, yếu tố Ấn Độ - Mã Lai chiếm ưu thế (8 loài; chiếm 40%), kế tiếp là các loài phân bố rộng (6 loài; chiếm 30%), yếu tố Trung Hoa kém đa dạng (4 loài; chiếm 20%) và thấp nhất là thành phần đặc hữu cho Việt Nam (2 loài; chiếm 10%)

Hogwild! over Distributed Local Data Sets with Linearly Increasing Mini-Batch Sizes

Hogwild! implements asynchronous Stochastic Gradient Descent (SGD) where multiple threads in parallel access a common repository containing training data, perform SGD iterations and update shared state that represents a jointly learned (global) model. We consider big data analysis where training data is distributed among local data sets in a heterogeneous way -- and we wish to move SGD computations to local compute nodes where local data resides. The results of these local SGD computations are aggregated by a central "aggregator" which mimics Hogwild!. We show how local compute nodes can start choosing small mini-batch sizes which increase to larger ones in order to reduce communication cost (round interaction with the aggregator). We improve state-of-the-art literature and show $O(\sqrt{K}$) communication rounds for heterogeneous data for strongly convex problems, where $K$ is the total number of gradient computations across all local compute nodes. For our scheme, we prove a \textit{tight} and novel non-trivial convergence analysis for strongly convex problems for {\em heterogeneous} data which does not use the bounded gradient assumption as seen in many existing publications. The tightness is a consequence of our proofs for lower and upper bounds of the convergence rate, which show a constant factor difference. We show experimental results for plain convex and non-convex problems for biased (i.e., heterogeneous) and unbiased local data sets.Comment: arXiv admin note: substantial text overlap with arXiv:2007.09208 AISTATS 202

Shrimp farming in Vietnam : at the crossroads of sustainability

International audienceShrimp farming in Vietnam was remained underdeveloped, in spite of good potential in terms of natural resources and farming area, when some Asian producing countries were facing serious environmental, technical and social collapses, known as the boom and burst of shrimp culture development. Lacks of investment, capital, technology and knowledge have been the main restrictive factors to the development of shrimp culture in Vietnam. The Doi Moi policy and institutional changes generated important factors facilitating large scale development by giving greater access to production factors. But the development of shrimp farming in Vietnam also took place at a time when debates about shrimp farming had been evolving through the introduction of new tools, concepts and methods, particularly in relation to the environmental and social impacts of the activity. After more that ten years of full development, Vietnam has become one of the most important producers on the international scheme. But while it is difficult to say if this development has fully matured, its sustainability is much more questionable. Learning from failures in other countries, accessing to better management over the uncertainties of production combined with a gradual decrease in prices, Vietnam is at a crossroads, torn between the temptation of pursuing a risky development as a source of foreign currency, and the need to place aquaculture at the core of local development and poverty alleviation at lower risk. The paper reviews this issue at the light of several international projects focussing on shrimp farming sustainability in Asia and particularly in Vietnam

Experimental Design, Equilibrium Modeling and Kinetic Studies on the Adsorption of Methylene Blue by Adsorbent: Activated Carbon from Durian Shell Waste

For the first time, activated carbon from a durian shell (ACDS) activated by H2SO4 was successfully synthesized in the present study. The fabricated ACDS has a porous surface with a specific surface area of 348.0017 m2·g−1, average capillary volume of 0.153518 cm3·g−1, the average pore diameter of 4.3800 nm; ash level of 55.63%; humidity of 4.74%; density of 0.83 g·cm−3; an iodine index of 634 mg·g−1; and an isoelectric point of 6.03. Several factors affecting Methylene Blue (MB) adsorption capacity of ACDS activated carbon was investigated by the static adsorption method, revealing that the adsorption equilibrium was achieved after 90 min. The best adsorbent pH for MB is 7 and the mass/volume ratio is equal to 2.5 g·L−1. The MB adsorption process of ACDS activated carbon follows the Langmuir, Freundlich, Tempkin, and Elovich isotherm adsorption model, which has determined the maximum adsorption capacity for MB of ACDS as qmax = 57.47 mg·g−1. The MB adsorption process of ACDS follows the of pseudo-second-order adsorption kinetic equation. The Weber and Morris Internal Diffusion Model, the Hameed and Daud External Diffusion Model of liquids have been studied to see if the surface phase plays any role in the adsorption process. The results of thermodynamic calculation of the adsorption process show that the adsorption process is dominated by chemical adsorption and endothermic. The obtained results provide an insight for potential applications of ACDS in the treatment of water contaminated by dyes

Enhanced Photocatalytic Degradation of Rhodamine-B under Led Light Using CuZnAl Hydrotalcite Synthesized by Co-Precipitation Technique

The co-precipitation method was employed to synthesize a set of ZnAl hydrotalcite materials modified by Cu2+. The synthesized materials have a similar lamellar structure to that of hydrotalcite. The distance between layers is in the range of 7.73–8.56 Å. The network parameters a and c ranged from 3.058 to 3.074 Å and from 23.01 to 24.44, respectively. According to the IUPAC classification, the composites possess a mesoporous structure which belongs to class IV, type H 3. Particularly, the absorption edge shifts strongly to the visible light region when increasing the molar ratio of Cu2+ in the samples from 0 to 3.5. The photocatalytic activity of the synthetic materials was evaluated through the degradation efficiency of rhodamine-B (Rh-B) in the water and colorants in textile wastewater. The present study was the first to synthesize a material sample that contains a molar ratio of Cu2+ in the range of 2.5–3.5 and has high catalytic activities. They were able to degrade Rh-B at a high concentration (100 ppm) with a conversion rate of approximately 90% after 240 min of irradiation using a 30 W LED light. The catalytic activity of the composites depends on the molar ratio of modified Cu2+, the value of environmental pH, the H2O2 concentration and the irradiation time