Collinear order in a frustrated three-dimensional spin-12\frac12 antiferromagnet Li2_2CuW2_2O8_8

Magnetic frustration in three dimensions (3D) manifests itself in the spin-$\frac12$ insulator Li$_2$CuW$_2$O$_8$. Density-functional band-structure calculations reveal a peculiar spin lattice built of triangular planes with frustrated interplane couplings. The saturation field of 29 T contrasts with the susceptibility maximum at 8.5 K and a relatively low N\'eel temperature $T_N\simeq 3.9$ K. Magnetic order below $T_N$ is collinear with the propagation vector $(0,\frac12,0)$ and an ordered moment of 0.65(4) $\mu_B$ according to neutron diffraction data. This reduced ordered moment together with the low maximum of the magnetic specific heat ($C^{\max}/R\simeq 0.35$) pinpoint strong magnetic frustration in 3D. Collinear magnetic order suggests that quantum fluctuations play crucial role in this system, where a non-collinear spiral state would be stabilized classically.Comment: published version with supplemental material merged into the tex

Diversity of reef fishes in trap fishery at Keelakarai, Gulf of Mannar, south-east coast of India

The diversity of finfishes caught in traps at Keelakarai, Gulf of Mannar was assessed quantitatively and qualitatively for a period of six years from July 2006 to June 2012. Average landing during the period was 109 t per year with maximum of 137 t during 2008-09. Among the 98 species of reef fishes landed, Siganus canaliculatus dominated (28%), followed by Scarus ghobban (21%). During the first two years of the study, S. ghobban dominated over S. canaliculatus and later the trend reversed. Family-wise, maximum contribution was by Siganidae (36%) followed by Scaridae (21%). Seasonally, the major peak was recorded during post-monsoon of 2009. The Shannon index of diversity was maximum during 2007-08. Cluster analysis indicated the highest similarity in species composition between 2010-11 and 2011-12. SIMPER analysis identified 26 species as most significant in creating the observed pattern of similarity for 90% cut off contributions. Ellipse plot showed statistically significant deviation in fish diversity between years. Reef fish landings showed an increasing trend from 2006-07 to 2008-09, a decline afterwards and then almost steady condition prevailed during the last two years of the study which implies that there is no scope for further increase in landings by trap fishery at Keelakarai

Coral bleaching: causes, consequences and mitigation

The coral reefs are distributed in the tropical regions and cover less than one percent of the earth’s surface, but provide habitat for many species in the marine realm. The majority of reef building corals are found in tropical and subtropical waters and typically occur between 30° N and 30° S latitudes (Fig. 1). Coral reefs are greatly valued due for their beauty, biodiversity it encompasses and the products and services they provide to human society. The coral reefs are made of calcium carbonate secreted as skeletal material by the coral polyp. Coral polyps live in association with intracellular algae (zooxanthellae), which provide additional nutrition to the coral in its life processes. The association of coral polyp with zooxanthellae, restrict its distribution in waters up to the depth of 100 meters where sunlight would be available for the photosynthetic zooxanthellae. The worldwide of zooxanthellate corals in the different distribution eco-regions is a unique underwater ecosystem and provides annual net economic benefit around 30 billion dollars (Buddemeier et al., 2004 Pew Center on Global Climate Change, 44p). However, coral reefs are most vulnerable to Climate Change due to the stenothermic nature of coral polyps

Biofilm-stimulated epithelium modulates the inflammatory responses in co-cultured immune cells

The gingival epithelium is a physical and immunological barrier to the microbiota of the oral cavity, which interact through soluble mediators with the immune cells that patrol the tissue at the gingival epithelium. We sought to develop a three-dimensional gingivae-biofilm interface model using a commercially available gingival epithelium to study the tissue inflammatory response to oral biofilms associated with “health”, “gingivitis” and “periodontitis”. These biofilms were developed by sequential addition of microorganisms to mimic the formation of supra- and sub-gingival plaque in vivo. Secondly, to mimic the interactions between gingival epithelium and immune cells in vivo, we integrated peripheral blood mononuclear cells and CD14+ monocytes into our three-dimensional model and were able to assess the inflammatory response in the immune cells cultured with and without gingival epithelium. We describe a differential inflammatory response in immune cells cultured with epithelial tissue, and more so following incubation with epithelium stimulated by “gingivitis-associated” biofilm. These results suggest that gingival epithelium-derived soluble mediators may control the inflammatory status of immune cells in vitro, and therefore targeting of the epithelial response may offer novel therapies. This multi-cellular interface model, both of microbial and host origin, offers a robust in vitro platform to investigate host-pathogens at the epithelial surface

Animal hygiene and sustainable livestock production: impact of ground water contamination with arsenic

There is a growing concern all over the world about contamination of ground water with Arsenic. One of the major repercussions of arsenic contamination is degradation of animal hygiene that ultimately affects sustainable livestock production. The reports suggest that concentration of Arsenic in ground water of twenty one countries is well above the guideline values. Use of such contaminated water for animal husbandry and livestock production compromises with the hygienic value of animal products. Therefore, there is an urgent need to develop low cost treatment technologies for reducing the level of arsenic in ground water to maintain the hygiene and sustainability of livestock production. Most of the traditional treatment technologies are costly and less effective in reducing arsenic concentration to safer limits. Therefore, during present study, an attempt was made to design a low-cost algal adsorbent based filtration unit consisting of polyurethane columns with entrapped algal adsorbents. The column was made of adsorbents of algal origin like agar-agar, alginic acid, calcium alginate and Spirulina platensis biomass entrapped in polyurethane foam matrix. The performance of the column was assessed in terms of removal efficiency and the quantity of metal sequestered in unit time interval. The results from the study the show that algal biosorbents and S. platensis biomass combination has a capacity to adsorbed arsenic from aqueous solution. The simple design, easy fabrication and no energy requirement for the operation of the filtration unit developed under the present study is suitable to rural areas where arsenic contamination of ground water is adversely affecting the animal hygiene and sustained livestock production

Marine Fisheries Policy Series-7; Conservation and sustainable use of sea cucumber resources in India suggestions and way forward

Sea cucumbers are prime seafood resources, harvested throughout the world for the preparation of a dried product ‘beche-de-mer’, besides other health products. However, in recent years, the wild population of sea cucumbers is on the decline due to the increasing market demand and the consequent over-harvest of resources. The global scenario of stock decline was witnessed in Indian waters too in the early 1980s, and as a regulatory measure, the Ministry of Environment, Forests & Climate Change (MoEF & CC), Government of India implemented a size regulation on the export of ‘beche-de-mer’ in 1982. As this regulation was not very effective, the Government imposed a blanket ban in the year 2001, and listed all species of holothurians under the Schedule I of the Indian Wildlife (Protection) Act, 1972, thereby putting an end to the sea cucumber fishery and trade from the country. In India, the fishery of sea cucumbers was restricted mainly to the Gulf of Mannar and Palk Bay, along the south-east coast and the moratorium imposed by the Government affected scores of coastal communities whose livelihood was dependent on the collection, processing and trade of sea cucumbers

Plankton Productivity in Lagoons of Agatti and Bangaram Atolls of Lakshadweep Archipelago, India

Phytoplankters and zooplankters function as important links in the food chain and form the food of a large number of organisms in the aquatic ecosystem. As plankters play an important role in the health of an aquatic ecosystem, the study on these resources in the productive aquatic ecosystems of Lakshadweep is significant. Earlier studies carried out earlier from Agatti and Bangaram are by Pratap et al. (1977), Achuthankutty et al. (1989) and Casanova & Nair (1999). No recent reports are available on plankters from Agatti and Bangaram. Hence, an attempt is made to study the qualitative and quantitative abundance of phytoplankters and zooplankters in the selected lagoons of Lakshadweep

Landings of juvenile Uroteuthis (Photololigo) singhalensis in Tuticorin Fishing Harbour

In Tuticorin Fishing Harbour about 200 trawlers operate daily from 5 am to 11 pm for single day fishing. Wooden and steel trawlers in three sizes, namely small boats (OAL 35-40 feet), medium boats (OAL 40-50 feet) and large boats (OAL up to 80 feet) operate from this harbour

Copepod Abundance and Diversity from Offshore Region of Tuticorin, South East Coast of India

A detailed study had been carried out on species abundance, biomass and composition of copepod in four different offshore stations namely, Station I: Vembar, II: Keelavaipar, III: Punnaikayal and IV: Thiruchendhur in Gulf of Mannar region from October 2011 to April 2012. A total of 56 copepod species belongs to 20 families under 4 orders have been encountered during the period. The percentage composition of different groups of copepod species was composed of Calanoida (35 numbers) 62.5%, Cyclopoida (4 numbers) 7.14%, Harpacticoida (8 numbers) 14.3% and Poecilostomatoida (9 numbers) 16.1%. The percentage of biomass composition of different groups of copepods during the study was in the order of Calanoida 38.99%, Harpacticoida 32.56%, Cyclopoida 15.22% and Poecilostomatoida 13.23%. In the case of species composition, Euterpina acutifrons (28.61%) was the most abundant species followed by Acrocalanus gracilis (17.68%), Corycaeus crassiusculus (12.33%), Oithona brevicornis (12.03%) and Temora turbinata (4.25%) were the other dominant species in observation. The copepod density in different stations were in the range of 8600–39900, 3900–64600, 3800–24800 and 5000–22500 numbers m-3 at station I, II, II and IV respectively. The lowest biomass of copepod was observed at station III and highest biomass was found at station II. The copepod species richness ranged from 0.48 to 2.72 and species diversity was in the range of 0.87 to 1.98 in the study areas. Species evenness was varied from 0.24 – 0.51 during the observation period

Incidence of kleptoparasitism on jelly fish Rhopilema hispidum from the Pamban coast of Palk Bay, Southeast coast of India

Incidence of kleptoparasitism on jelly fish Rhopilema hispidum from the Pamban coast of Palk Bay, Southeast coast of Indi