Overfishing Trends and the Global Food Crisis

Fish are a vital source of nourishment, especially to people in the world's poorest nations. Widespread over?shing has led to a decline in catch globally; however, the links between over?shing and food security have not been well-understood. The authors of scientific article "Food security implications of globalmarine catch losses due to overfishing." assessed potential losses, globally and regionally, in ?sheries catch and revenue resulting from over?shing. They found a third to a half of commercial marine species had been over?shed during the past half-century, with billions in potential revenue lost. By placing country-level catch loss trends in the context of undernourishment levels in many of the world's poorest countries, the authors estimated that in 2000 the additional catch from sustainable ?shing could have helped 20 million people cover their food de?cit and avert undernourishment. This Pew Ocean Science Series report is a summary of the scientists' ?ndings

Study on selective laser sintering components with electrically conductive channels

Electrically conductive channe ls were created using conductive carbon cement (CCC) by a simple non-contact continuous deposition method on sintered DuraFormTM Polyamide parts. The deposition system consisted of a drive circuit, a Micro Inert Solenoid Valve (MIV), a nozzle head and two liquid material reservoirs. Effect of CCC/solvent ratio, speed of deposition head and sintering condition of the Polyamide base material on the electrical properties of the conductive channels were investigated. The paper will then go on to discuss how these results relate to potential applications of Selective Laser Sintering (SLS) components with electrical property.Mechanical Engineerin

Selective Laser Sintered CastForm™ Polystyrene with Controlled Porosity and Its Infiltration Characteristics by Red Wax

This paper focuses on the manufacture of polymer-based components with controlled porosity using selective laser sintering (SLS) and on their infiltration characteristics by red wax. CastFormTM Polystyrene (CF) samples with various densities were created by controlling the laser energy density. Wax was then infiltrated into the sintered specimens at around 638C to 648C. The microstructures of the sintered specimens were examined using scanning electron microscopy. The physical density was found to increase with increasing energy density and it reached a maximum at energy density of 0.11 J/mm2 . The infiltration rate and mass of infiltrant absorbed in a given time were found to increase with increasing porosity. However, none of the specimens could be fully infiltrated and about 10 – 20 % of porosity still remained regardless of energy density used for the sintering process. Finally, the potential applications of SLS parts with controlled porosity will be discussed.This paper describes a project funded by the Research Grants Council on ‘Functionally graded part fabrication based on the SLS process’.Mechanical Engineerin

Material Movement and Fusion Behavior of TrueForm and TrueForm/SiO2 during Selective Laser Sintering

Different material systems, TrueForm and TrueForm/SiO2 composites, were sintered under similar conditions. A microscope equipped with a CCD camera was utilized to examine the material movement near the laser beam. Powder movement of the blends was found to start at different ranges ahead of the line of scan. For TrueForm, the polymer particles were found to undergo fusion ahead of the laser beam and form a band, 0.5-0.7mm wide, which then moved as a single block towards the sintered area. The dry mixed TrueForm/SiO2 composites (dry blends) exhibited a short-range material movement in the form of small agglomerates. Meanwhile, the TrueForm/SiO2 composite powder prepared by melt extrusion (melt blend) showed a range of material movement between those of TrueForm and the dry blends. The discrepancy is believed to arise from changes in heat transfer properties and fusion behavior after blending. The surface temperature of the powder bed was monitored during sintering. Generally, the dry blends exhibited a higher surface temperature. Apparently, both the particle size of SiO2 and the blending method had an effect on the temperature and material movement, and hence on the final morphology of the sintered components.Mechanical Engineerin

A Structural Equation Model Examining the Cultural Relevance of Physical Self-Concept and Self-Esteem in Chinese Children

Objectives: The purposes of this study were to investigate: (1) whether three subscale scores (i.e.,body fat, appearance, and strength) and the global physical self-concept and global self-concept scores of the Physical Self-Description Questionnaire (PSDQ) are applicable to Chinese children; (2) whether there is a gender difference in these relationships; and (3) whether global physical self-concept acts as a mediator of global self-concept. Method: 320 Chinese children aged 7-12 years were recruited. The PSDQ was used to assess two global dimensions (global physical self-concept and global self-concept) and three specific dimensions (body fat, appearance, and strength) of self-worth. The children’s version of the silhouette matching task (SMT) was adopted from Marsh and Roche (1996) to measure children’s body perception. Results: The factor structure of the modified PSDQ model was applicable in young Chinese children, regardless of their gender. Results of structural equation model (SEM) indicated that the model was acceptable. The structural paths of the model and the mediating effect of global physical self-concept on global self-concept were discussed. Conclusion: The present study indicates that the physical self is an increasingly important correlate of self-esteem. It is particularly important relative to perceived self-presentation and social acceptance. Therefore, it is important to consider the impact of the physical self-concept on global self-concept from both cultural and worldwide perspectives

Ocean Science Series: Redistribution of Fish Catch by Climate Change

Global climate change is expected to affect marine fisheries productivity because of changes in water temperature, ocean currents and other ocean conditions. Marine fisheries are an important food source, and changes in the total amount or geographic distribution of fish available for catch could affect food security. Changes in marine food supply due to climate change, however, were previously unknown

Socio-economic Impacts—Fisheries

Fishers and scientists have known for over 100 years that the status of fish stocks can be greatly influenced by prevailing climatic conditions. Based on historical sea surface temperature data, the North Sea has been identified as one of 20 ‘hot spots’ of climate change globally and projections for the next 100 years suggest that the region will continue to warm. The consequences of this rapid temperature rise are already being seen in shifts in species distribution and variability in stock recruitment. This chapter reviews current evidence for climate change effects on fisheries in the North Sea—one of the most important fishing grounds in the world—as well as available projections for North Sea fisheries in the future. Discussion focuses on biological, operational and wider market concerns, as well as on possible economic consequences. It is clear that fish communities and the fisheries that target them will be very different in 50 or 100 years’ time and that management and governance will need to adapt accordingly

Recreational specialization and the marine-based conservation behaviour intention of recreational divers in Hong Kong

This study examined divers' recreational specialization, pro-environmental attitudes, and marine-based conservation behaviour intentions. A questionnaire-based data collection approach was used to survey 398 divers who visited popular diving sites in Hong Kong by employing structural equation modelling to determine the potential relationships among the proposed variables. The results showed a statistically positive relationship between divers' recreational specialization and their pro-environmental attitudes, along with a statistically valid relationship between divers' recreational specialization and their marine-based conservation behaviour intentions. However, divers' pro-environmental attitudes were not statistically significant with their marine-based conservation behaviour intentions; thus, the discrepancy regarding different research findings between the current and previous studies was further discussed. In particular, our findings confirmed that recreational specialization could be a reliable predictor of divers' pro-environmental attitudes and marine-based conservation behaviour intentions to fill the research gaps regarding scuba diving-based nature tourism in Hong Kong. Consequently, management implications and recommendations were presented in accordance with the development of marine environmental conservation and sustainable scuba diving tourism in Hong Kong