Analysis of a Colonial Alphabet Book

This essay analyzes a non-canonical alphabet book written in the nineteenth century. The Colonial Alphabet For The Nursery was written for the child audience during the Victorian era. It associates a word with each letter of the alphabet, and the word is used in a sentence describing its corresponding illustration. This paper explains how the book portrays Great Britain as a world superpower by showing the other countries as poor and insignificant. Much of this alphabet book teaches children the various stereotypes about numerous ethnicities. This allows for them to grow up with misconceptions about diverse racial groups. This essay describes how the text encompasses the theme of nature to educate the child reader on the dominance of Britain

On the character degree graph of solvable groups

Let $G$ be a finite solvable group, and let $\Delta(G)$ denote the \emph{prime graph} built on the set of degrees of the irreducible complex characters of $G$. A fundamental result by P.P. P\'alfy asserts that the complement $\bar{\Delta}(G)$ of the graph $\Delta(G)$ does not contain any cycle of length $3$. In this paper we generalize P\'alfy's result, showing that $\bar{\Delta}(G)$ does not contain any cycle of odd length, whence it is a bipartite graph. As an immediate consequence, the set of vertices of $\Delta(G)$ can be covered by two subsets, each inducing a complete subgraph. The latter property yields in turn that if $n$ is the clique number of $\Delta(G)$, then $\Delta(G)$ has at most $2n$ vertices. This confirms a conjecture by Z. Akhlaghi and H.P. Tong-Viet, and provides some evidence for the famous \emph{$\rho$-$\sigma$ conjecture} by B. Huppert

Use of Selected Periphyton Species to Improve the Water Quality and Shrimp Postlarval Production

In marine shrimp larval rearing practices, a large amount of water has to be exchanged frequently in order to maintain good water quality. This procedure contributes to the eutrophication of aquatic environment due to flushing of nutrient-enriched waters from aquaculture facilities. Furthermore, the process of frequent water exchange will eventually result in lack of good water supply which can also increase the risk of diseases in the hatchery. To overcome eutrophication and the risk of diseases, an alternative eco-friendly method was investigated to decrease harmful compounds especially ammonia and nitrite by using periphyton grown on substrates. Different periphyton species (Oscillatoria, Navicula sp., Cymbella sp. and Amphora sp.) from marine shrimp culture ponds were isolated, purified and mass cultured in the laboratory and grown in Conway medium. The effects of salinity (0, 15, 20, 25, 30 and 35 ppt) on the growth of these genera under aboratory condition was determined. The highest (p<0.05) growth was achieved at 25-35 ppt salinity. Nutritional composition of different periphyton genera were analysed to determine their importance as shrimp feed. All periphyton genera contained high protein (Oscillatoria 42%, Cymbella 43%, Navicula 49% and Amphora 44% of dry wt.), lipid (Oscillatoria 20%, Cymbella 26%, Navicula 26% and Amphora 23% of dry wt.) and carbohydrates (Oscillatoria 24%, Cymbella 20%, Navicula 11% and Amphora 18% of dry wt.). The periphyton genera also contained of docosahexaenoic acid (DHA) (Navicula 2%, Cymbella 2%, and Amphora 3%, Oscillatoria 1% of total lipid) and ecosapentaenoic acid (EPA) (Amphora 15%, Cymbella 3%, Navicula 8% and Oscillatoria 1% of total lipid). Periphyton colonization using different substrates (bamboo, polyvinylchloride pipe, plastic sheet, fibrous scrubber and ceramic tile) in intensive shrimp culture ponds were studied for a period of 60 days. Nineteen periphyton genera dominated by the Chlorophyceae colonized the substrates during the first 15 days. Periphyton colonization on bamboo showed the highest biomass (p<0.05) amongst all the substrates used. Biomass of periphyton in terms of chlorophyll-a varied from 179 to 1137 μg m-2 with mean values of 1137 ± 0.6, 929 ± 0.6, 684 ± 1.2, 179 ± 0.6 and 658 ± 0.6 μg m-2 on bamboo, polyvinyl chloride (PVC) pipe, plastic sheet, fibrous scrubber and ceramic tile respectively on first 15 days. Effectiveness of different periphyton genera in reducing total ammonia nitrogen (TAN), nitrite nitrogen (NO2–N) and soluble reactive phosphorous (SRP) in hatchery tanks without shrimp postlarvae were studied for a period of 16 days. It was found that Oscillatoria significantly reduced (p<0.05) TAN (90%), SRP (83%) and NO2–N (91%) whereas diatom species decreased 60%, 74% and 78% of the same parameters respectively. In addition, Oscillatoria yielded the highest (p<0.05) biomass compared to other periphyton species. Results of this study showed that all the periphyton genera were able to significantly reduce TAN, SRP and NO2-N concentrations in larval rearing tanks. The use of periphyton coated substrate (periphyton grown on polyvinylchloride pipes) for improving water quality and survival of shrimp postlarvae in hatchery without water exchange was studied for a period of 16 days. Periphyton species significantly reduced (p<0.05) TAN in shrimp culture tanks as compared to the control (without periphyton coated substrate). Amongst the treatments, tanks with Oscillatoria had the lowest mean TAN (0.09 ± 0.00 mg L-1) compared to tanks with diatoms (3.77 ± 0.17 mg L-1) and the control (5.17 ± 0.08 mg L-1). Similarly, NO2–N (0.04 ± 0.00 mg L-1) and SRP (0.22 ± 0.00 mg L-1) concentrations were significantly (p<0.05) lower in the shrimp culture tanks with periphyton species than the control (4.13 ± 0.24 mg L-1). Shrimp cultured with periphyton coated substrate showed significantly higher survival (51% - 60%) than those without periphyton (37%). In addition, the shrimp postlarvae produced in this system showed high resistance to reverse salinity stress test (37% - 43%) compared to the control (26%). This study illustrated that beneficial Periphyton species could improve water quality, provide live feed and serve as refugium for the shrimp postlarvae

Biological approaches in management of nitrogenous compounds in aquaculture systems.

Aquaculture is the fastest growing food-producing sector accounting for almost 43% of the world's food fish. There is however a need to increase aquaculture production in the next two decades in order to satisfy the minimum protein requirement for human nutrition. There are many constraints that limit the maximum production in aquaculture systems such as water quality and adequate live feeds. With the development of modern aquaculture farming, extensive culture has given way to intensive culture systems. In intensive systems, cultured organisms are fed protein-rich formulated feeds. Uneaten feed along with metabolic wastes and other organic matters decompose resulting in an increase of toxic nitrogenous compounds causing deterioration of water quality which is toxic to cultured organisms. The discharge of a large amount of nutrient-rich wastes from these aquaculture systems, the majority of which are nitrogenous compounds, promotes eutrophication in water bodies. In general, an increase of nitrogenous compounds has adverse effects on the environment and on aquaculture production. The aim of this paper is to highlight some of the trends in biological management of nitrogenous substances in aquaculture systems

Effects of salinity on the growth and proximate compositon of selected tropical marine periphytic diatoms and cyanobacteria.

Marine periphytic cyanobacteria and diatoms have been examined as a potential source of feed supplement for rearing aquatic larvae in the aquaculture industry. Culture of the periphytic diatom Amphora sp., Navicula sp., Cymbella sp. and the cyanobacteria Oscillatoria sp. at different salinities showed significant changes in biomass and specific growth rates. Diatoms growth was significantly higher at 35 g L−1, while for cyanobacteria growth was better at 25 g L−1. Significantly higher levels of protein and lipid were found in diatoms at low salinities (15–25 g L−1) and an increase in carbohydrate at high salinities (30–35 g L−1). Conversely, cyanobacteria showed a significantly higher lipid content at 30–35 g L−1 compared with other salinity levels but no significant changes were observed in the protein and carbohydrate contents at different salinity levels. The present findings can be taken into consideration when culturing marine periphytic Amphora sp., Navicula sp., Cymbella sp. and Oscillatoria sp. to provide appropriate levels of protein, lipid and carbohydrate as feed supplement as well as for bioremediation in aquaculture