Magnetic wire-based sensors for the micro-rheology of complex fluids

We propose a simple micro-rheology technique to evaluate the viscoelastic properties of complex fluids. The method is based on the use of magnetic wires of a few microns in length submitted to a rotational magnetic field. In this work, the method is implemented on a surfactant wormlike micellar solution that behaves as an ideal Maxwell fluid. With increasing frequency, the wires undergo a transition between a steady and a hindered rotation regime. The study shows that the average rotational velocity and the amplitudes of the oscillations obey scaling laws with well-defined exponents. From a comparison between model predictions and experiments, the rheological parameters of the fluid are determined.Comment: 14 pages 7 figures, accepted in Physical Review

Targeted trawl fishery for moontail bullseye, Priacanthus hamrur off Mangalore for surumi production

Moontail bullseye, Priacanthus hamrur has been forming a part of the trawl fishery off Mangalore, caught from a depth beyond 100 m ever since deepsea trawling started off the coast. This is not a preferred edible species in Karnataka and was not a species considered for targeted fishery

Unusual catch rates of cuttlefish in a multiday trawler

Cuttlefish is one of the commercially important group of cephalopods caught by multi-night trawlers along the coast of Karnataka. The catch rate of cuttlefish in multiday trawlers varies from <5 kg/haul during December-April period to 50-300 kg/haul during the peak fishing season in August- September

Observations on the landing of Odonus niger at Mangalore

The redtoothed triggerfish (Odonus niger) of the family Balistidae is a reef associated species landed by trawl nets operated along the Karnataka coast. This species forms dense aggregations in inshore waters and were not targeted till recently due to their poor market demand. The triggerfish shoals are intentionally avoided by the trawlers and the incidental catches are either discarded or brought ashore when there is available deck space for storage. Such small quantities landed are auctioned along with the miscellaneous fish groups. Some interest was evinced on this species by the fish meal traders due to limited availability of raw materials during the year 2008

Emerging small scale trap fishery for whelk, (Babylonia spirata) in Malpe, Southern Karnataka

Babylonia spirata is a commercially important edible gastropod found inhabiting the coastal waters with sandy bottom. Commonly known as whelks, they are landed as by-catch in shrimp trawlers in Kerala and Tamilnadu.There is an emerging fishery for whelks along the Malpe coast (13° 21’ N and 74°42’5” E) with the increase in export demand. Specially designed whelk traps are operated from traditional fishing crafts to collect whelks since January 2005

Gillnet and hook & line fishing off Mangalore

Fishing using gillnets and hooks and line have been in vogue along Mangalore coast since a long time. These fishing practices are very popular and found to be lucrative along coastal Karnataka. Fishing using gillnets and hooks and line has so far been operated only Mar. Fish. Infor. Serv., T&E Ser., No. 188, 2006 6 from canoes fitted with outboard engines (OBM). The fishermen fish for a day or night or at the most for 2-3 days. However, of late, mechanized crafts (inboard mechanized) operating gillnets as well as hooks and line land their catch at Mangalore Fisheries Harbour. The crafts used are large and comparable to the size of trawlers and purseseiners of Mangalore and have an endurance to stay out at sea for more than a month. As this kind of fishing activity is new to this area, the catch as well as gear details were studied and a brief account is given

High abundance of large sized rock cods (Epinephelus spp.) off Karnataka coast during the postmonsoon month of September

some of the multi-day units ventured into deeper waters (60-80 m) and obtained good catches of reef cods (Fig: 1) along with threadfin breams and cuttle fishes. Encouraged by this, more number of multi-day units were put into operation in September of the following year (1995) and got still better catches of reef cods

Tropical Dominating Sets in Vertex-Coloured Graphs

Given a vertex-coloured graph, a dominating set is said to be tropical if every colour of the graph appears at least once in the set. Here, we study minimum tropical dominating sets from structural and algorithmic points of view. First, we prove that the tropical dominating set problem is NP-complete even when restricted to a simple path. Then, we establish upper bounds related to various parameters of the graph such as minimum degree and number of edges. We also give upper bounds for random graphs. Last, we give approximability and inapproximability results for general and restricted classes of graphs, and establish a FPT algorithm for interval graphs.Comment: 19 pages, 4 figure

Pufferfish Lagocephalus inermis - an emerging fishery along Mangalore coast of Karnataka

L agocephalus inermis (Temminck & Schlegel, 1850) commonly known as smooth blaasop, belongs to the family Tetraodontidae and order Tetraodontiformes. This fish was considered as a menace by fishermen during the previous year (2006) as it caused damage to other species landed and the net