Divergences in learning and memory among wild zebrafish: Do sex and body size play a role?

Given its diverse ecological distribution, zebrafish has great potential for investigations on the effect of habitat characteristics on cognition. Studies were conducted on four wild-caught zebrafish populations to understand the role of native habitat, sex, and body size in determining learning through a novel task associated with a food reward. The habitat variables, namely, the relative abundances of zebrafish and predatory fish and the substrate and vegetation diversity, were quantified during fish sampling. Fish were subjected to a novel task to find a food reward in a maze over successive training trials followed by a test for memory. Performances of subjects were based on time taken to find the food reward and number of mistakes made during trials, and tests for memory. The experiments revealed significant differences in learning rates and memory across populations. Males made significantly fewer mistakes than females only within two populations. No relationship between performance and body size was observed. The differences in learning and memory among wild zebrafish could be due to differences in predation, complexity, and stability of the native habitats. These findings suggest the possible role of multiple interacting factors in determining learning and memory among populations and point to a need for incorporating effects of several factors in future studies.     

Degree Switching Operations in Networks and Large Scale Systems Assignment Problems

In this paper an algorithm is presented for listing all output sets for a large sparse square matrix A arising in large scale systems applications using network theory and the degree switching operations. The algorithm exploits the zero nonzero structure of matrix A and uses optimum data structures and data manipulation methods. The method is shown to be useful in finding all optimum assignments in an n x n optimum assignment problem and generation of all digraphs that can be associated with an n x nsparse matrix. The problem of testing whether there exists a set of vertex disjoint cycles of specified lengths in a network is shown to be NP-complete.     

Optimum tearing in large scale systems and minimum feedback cutsets of a digraph

In this paper we consider the problem of finding a minimum number of nonzero elements of a given nxn matrix on removal of which the resulting matrix can be permuted to an nxn lower triangular matrix using summetric permutations on the rows and columns of the matrix. The problem is related to finding a minimum feedback cutset for the digraph of the matrix. A topological method for finding a minimum feedback cutset for a given digraph is presented. Possible extensions to our work are indicated.     

Think it over

This section of Resonanceis meant to raise thought-provoking, interesting, or just plain brainteasing questions every month, and discuss answers a few months later. Readers are welcome to send in suggestions for such questions, solutions to questions already posed, comments on the solutions discussed in the journal, etc. to ResonanceIndian Academy of Sciences, Bangalore 560 080, with “Think It Over” written on the cover or card to help us sort the correspondence. Due to limitations of space, it may not be possible to use all the material received. However, the coordinators of this section (currently R Nityananda and C S Yogananda) will try and select items which best illustrate various ideas and concepts, for inclusion in this section.     

Online Bullying among High-School Students in India

Six hundred and forty high-school students (Grades 7–12) from a large central government school in South India participated in this exploratory study of online bullying (cyberbullying) in India. Participants responded to the Survey on Social Use of Information and Communications Technology (SSUICT; Bhat and Ragan 2013). Findings indicated that approximately half the participants experienced online bullying in one or more roles described by Bhat et al. Education about Asia, 2(18), 36–39, (2013), with these being: initiating online bully, secondary online bully, bystander, or target of online bullying. Overall, engagement in online bullying tended to increase with grade level, and participation in the role of secondary online bully was the highest of the four roles for Grades 8–12. Male participants reported higher engagement in all four roles than female participants, and this difference was significant for the roles of initiating online bully, secondary online bully, and target of online bullying. Significant correlations were found between the four roles of online bullying. Recommendations for addressing the issue of online bullying in the Indian context are provided, along with limitations of the study and suggestions for future research.     

Jack St. Clair Kilby

The electronics Integrated Circuit (IC) chips have enabled us to create intelligence on silicon (Si). Hence the impact of electronics manufacturing cuts across the entire industrial ecosystem. The IC chip is arguably one of the most profound inventions of the last century. Since the invention of the semiconductor transistor towards the end of the year 1947, the entire electronic industry was struggling to deal with the tyranny of numbers ?? the difficult problem of manually assembling a large of number of transistors on a board to realize complex circuits. This is when Jack S. Kilby entered the stage in the year 1958. He was a hands-on engineer with a lot of imagination and intuition, but grounded to reality with a lot of practical experience. He proposed a revolutionary concept of creating all components of an electronic circuit, insitu, on a single semiconductor piece. He successfully implemented this idea on September 12, 1958, by realizing a phase shift oscillator on a small piece of germanium (Ge), the first ever electronics IC chip. The importance of this milestone in the modern history of science and technology is highlighted by the fact that Jack Kilby received the Nobel prize in Physics, in the year 2000. The story of Jack Kilby and his remarkable achievements are very inspiring for all ages.     

Identification of a Rare Hemoglobin Variant HbJ-Rajappen [alpha90 (FG2) Lys?→?Thr] Using Mass Spectrometry

Hemoglobin J-Rajappen (alpha)90 Lys → Thr is an alpha chain variant found in heterozygous state and presents normal hematological blood picture. Due to the ambiguity in results obtained while analyzing by HPLC and alkaline gel electrophoresis, we report this rare case of HbJ-Rajappen using non denaturing gel electrophoresis and matrix assisted laser desorption ionization mass spectrometry. Though HbJ-Rajappen has earlier been reported using different techniques, this is the first report being validated using mass spectrometry technique.     

Wigner’s semicircle law and free independence

Free probability theory is a mathematical generlization of classical probability theory. For free central limit theorem we get the semicircle law as the limit law. E P Wigner came across this probability distribution while studying random matrices.     

An Algorithm for finding optimum path in networks

In this paper we present an O(¦V·log¦V) algorithm for finding an optimum path between two nodes in an edge-sparse network using a new approach. The method exploits the data structure and a simple breadth-first search process.     

Serum PCT and its Relation to Body Weight Gain in Pulmonary Tuberculosis

The present study was aimed at assessing alterations in serum PCT in terms of its relation to body weight gain in pulmonary tuberculosis (PTB) patients undergoing treatment. Among patients (25–75 years) diagnosed with pulmonary tuberculosis, those that were new smear positive, showed sputum conversion at the end of 2 months and were declared clinically cured at the end of 6 months, were included in the study (n = 40). Serum procalcitonin was determined by BRAHMS PCT-Q kit. Patients were divided into two study groups—Group 1 (n = 21; serum PCT > 2 ng/ml at diagnosis), Group 2 (n = 19; serum PCT > 10 ng/ml at diagnosis). Body weights of all patients were obtained at three different time points, PTB-0 (at diagnosis), PTB-2 (after 2 months of intensive treatment) and PTB-6 (after 6 months of treatment). In both groups, mean body weights at PTB-2 and PTB-6 were significantly higher than those at PTB-0 and at PTB-6 were significantly higher than those at PTB-2. However, percentage body weight gain following 2 months of intensive treatment was higher in group 1 (4.05 % gain, p < 0.01) than in group 2 (2.75 % body weight gain, p < 0.05). Thus, the percentage gain in group 1 was tending more towards the desirable minimum gain of 5 % during intensive phase. Increase in serum PCT levels in pulmonary tuberculosis is inversely associated with body weight gain during treatment. Thus, PCT could play a role in regulation of body weight gain in anorectic conditions like tuberculosis.