Effect of Stocking Density on the Growth, Survival, and Settlement of Sandfish Sea Cucumber (Holothuria scabra)

The US Affiliated Pacific Islands of Micronesia have several commercially important species of sea cucumbers in their water including the sandfish sea cucumbers, Holothuria scabra. Due to their commercial importance, they have been widely exploited and are in the danger of being extinct. The College of Micronesia Land Grant Program has undertaken the development of hatchery-based sandfish sea cucumber farming technology for local community based economic development, future commercialization, and restocking the depleted stocks in the wild. In this regard, an experiment was conducted to find out the effect of different stocking densities on the growth, survival, and settlement of sandfish sea cucumber larvae. Larvae were stocked at 1000, 500, 250, and 125 larvae in triplicates in 15 liter buckets. The experiment was run for 20 days at the end of which growth, survival, and settlement were tabulated for each treatment. After spawning, the larvae were obtained from the spawning of 45 broodstocks which were retrieved from the wild. The larval rearing was maintained in 15 liter buckets with four replication (15,000, 7,500, 3,750 and 1,875) larvae in three buckets for each treatment. The buckets subsequently changed water after two days and were fed with proportion of algae based on the stocking density. The settlement rate was counted after 5 days when introduced algamag plates. The results significantly show that the main factor affecting survival and growth is the stocking density and water environment. Therefore, the experiment should be continued to give evident results for which stocking density is more appropriate

The production and detoxification of a potent cytotoxin, nitric oxide, by pathogenic enteric bacteria

The nitrogen cycle is based on several redox reactions that are mainly accomplished by prokaryotic organisms, some archaea and a few eukaryotes, which use these reactions for assimilatory, dissimilatory or respiratory purposes. One group is the Enterobacteriaceae family of Gammaproteobacteria, which have their natural habitats in soil, marine environments or the intestines of humans and other warm-blooded animals. Some of the genera are pathogenic and usually associated with intestinal infections. Our body possesses several physical and chemical defence mechanisms to prevent pathogenic enteric bacteria from invading the gastrointestinal tract. One response of the innate immune system is to activate macrophages, which produce the potent cytotoxin nitric oxide (NO). However, some pathogens have evolved the ability to detoxify NO to less toxic compounds, such as the neuropharmacological agent and greenhouse gas nitrous oxide (N2O), which enables them to overcome the host's attack. The same mechanisms may be used by bacteria producing NO endogenously as a by-product of anaerobic nitrate respiration. In the present review, we provide a brief introduction into the NO detoxification mechanisms of two members of the Enterobacteriaceae family: Escherichia coli and Salmonella enterica serovar Typhimurium. These are discussed as comparative non-pathogenic and pathogenic model systems in order to investigate the importance of detoxifying NO and producing N2O for the pathogenicity of enteric bacteria

Synthesis and biological evaluation of sugars containing α,β-Unsaturated γ-Lactones

The stereocontrolled synthesis of new sugar derivatives carrying the α,β-unsaturated δ-lactone (butenolide) moiety is described. Sugar-fused or sugar-linked butenolides can be constructed by an efficient reaction sequence involving Wittig olefination of 3- or 5-keto sugars and intramolecular cyclization of the intermediate γ-hydroxy α,β-unsaturated esters. The antimicrobial activities of the products and that of a known sugar-derived pyranoid α,β-unsaturated δ-lactone were investigated against six pathogenic bacteria and six fungi. The pyranoid α,β-unsaturated δ-lactone 29 proved to be the most active compound in this series towards the plant pathogenic fungi Colletotrichum coffeanum (coffee berry disease) and Pyricularia oryzae (rice blast disease)

Violence, security and democracy: perverse interfaces and their implications for states and citizens in the global South

How does violence affect the everyday lives of citizens in the global South? Researching this theme under the aegis of the Violence, Participation and Citizenship group of the Citizenship DRC coordinated by IDS, we generated some answers, but also more questions, which this paper starts to explore. Why have democratisation processes failed to fulfil expectations of violence reduction in the global South? How does violence affect democracy and vice versa? Why does security practice in much of the global South not build secure environments? When examined empirically from the perspectives of poor Southern citizens, the interfaces between violence, security and democracy – assumed in conventional state and democratisation theory to be positive or benign – are often, in fact, perverse. Empirically-based reflection on these questions leads us to two propositions, which the paper then explores through the use of secondary literature. In essence: Proposition 1: Violence interacts perversely with democratic institutions, eroding their legitimacy and effectiveness. Democracy fails to deliver its promise of replacing the violence with accommodation and compromise, and democratic process is compromised, with citizens reacting by withdrawing from public spaces, accepting the authority of non-state actors, or supporting hard-line responses. Proposition 2: Security provision is not making people feel more secure. State responses to rising violence can strengthen state and non-state security actors committed to reproducing violence, disproportionately affecting the poorest communities

Entrenchment or Enhancement: Could Climate Change Adaptation Help to Reduce Chronic Poverty?

In the context of climate change, the poorest people are commonly seen as having the least capacity to adapt. However, to date, there has been a limited examination of the dynamic and differentiated nature of poverty. Through bringing together both the chronic poverty and adaptation literature, this article presents a new pro-poor adaptation research agenda underpinned by a more nuanced understanding of poverty. Whilst recognising that poverty reduction efforts are threatened by climate change, this article investigates ways in which proactive adaptation could offer opportunities to create pathways out of chronic poverty through targeted vulnerability reduction and adaptation efforts

The AgMIP Coordinated Climate-Crop Modeling Project (C3MP): Methods and Protocols

Climate change is expected to alter a multitude of factors important to agricultural systems, including pests, diseases, weeds, extreme climate events, water resources, soil degradation, and socio-economic pressures. Changes to carbon dioxide concentration ([CO2]), temperature, andwater (CTW) will be the primary drivers of change in crop growth and agricultural systems. Therefore, establishing the CTW-change sensitivity of crop yields is an urgent research need and warrants diverse methods of investigation. Crop models provide a biophysical, process-based tool to investigate crop responses across varying environmental conditions and farm management techniques, and have been applied in climate impact assessment by using a variety of methods (White et al., 2011, and references therein). However, there is a significant amount of divergence between various crop models’ responses to CTW changes (R¨otter et al., 2011). While the application of a site-based crop model is relatively simple, the coordination of such agricultural impact assessments on larger scales requires consistent and timely contributions from a large number of crop modelers, each time a new global climate model (GCM) scenario or downscaling technique is created. A coordinated, global effort to rapidly examine CTW sensitivity across multiple crops, crop models, and sites is needed to aid model development and enhance the assessment of climate impacts (Deser et al., 2012)..

Implementation of Adaptive Digital Controllers on Programmable Logic Devices

Much has been made of the capabilities of FPGA's (Field Programmable Gate Arrays) in the hardware implementation of fast digital signal processing. Such capability also makes an FPGA a suitable platform for the digital implementation of closed loop controllers. Other researchers have implemented a variety of closed-loop digital controllers on FPGA's. Some of these controllers include the widely used proportional-integral-derivative (PID) controller, state space controllers, neural network and fuzzy logic based controllers. There are myriad advantages to utilizing an FPGA for discrete-time control functions which include the capability for reconfiguration when SRAM-based FPGA's are employed, fast parallel implementation of multiple control loops and implementations that can meet space level radiation tolerance requirements in a compact form-factor. Generally, a software implementation on a DSP (Digital Signal Processor) or microcontroller is used to implement digital controllers. At Marshall Space Flight Center, the Control Electronics Group has been studying adaptive discrete-time control of motor driven actuator systems using digital signal processor (DSP) devices. While small form factor, commercial DSP devices are now available with event capture, data conversion, pulse width modulated (PWM) outputs and communication peripherals, these devices are not currently available in designs and packages which meet space level radiation requirements. In general, very few DSP devices are produced that are designed to meet any level of radiation tolerance or hardness. The goal of this effort is to create a fully digital, flight ready controller design that utilizes an FPGA for implementation of signal conditioning for control feedback signals, generation of commands to the controlled system, and hardware insertion of adaptive control algorithm approaches. An alternative is required for compact implementation of such functionality to withstand the harsh environment encountered on spacecraft. Radiation tolerant FPGA's are a feasible option for reaching this goal