On Rotation Distance of Rank Bounded Trees

Computing the rotation distance between two binary trees with $n$ internal nodes efficiently (in $poly(n)$ time) is a long standing open question in the study of height balancing in tree data structures. In this paper, we initiate the study of this problem bounding the rank of the trees given at the input (defined by Ehrenfeucht and Haussler (1989) in the context of decision trees). We define the rank-bounded rotation distance between two given binary trees $T_1$ and $T_2$ (with $n$ internal nodes) of rank at most $r$, denoted by $d_r(T_1,T_2)$, as the length of the shortest sequence of rotations that transforms $T_1$ to $T_2$ with the restriction that the intermediate trees must be of rank at most $r$. We show that the rotation distance problem reduces in polynomial time to the rank bounded rotation distance problem. This motivates the study of the problem in the combinatorial and algorithmic frontiers. Observing that trees with rank $1$ coincide exactly with skew trees (binary trees where every internal node has at least one leaf as a child), we show the following results in this frontier : We present an $O(n^2)$ time algorithm for computing $d_1(T_1,T_2)$. That is, when the given trees are skew trees (we call this variant as skew rotation distance problem) - where the intermediate trees are restricted to be skew as well. In particular, our techniques imply that for any two skew trees $d(T_1,T_2) \le n^2$. We show the following upper bound : for any two trees $T_1$ and $T_2$ of rank at most $r_1$ and $r_2$ respectively, we have that: $d_r(T_1,T_2) \le n^2 (1+(2n+1)(r_1+r_2-2))$ where $r = max\{r_1,r_2\}$. This bound is asymptotically tight for $r=1$. En route our proof of the above theorems, we associate binary trees to permutations and bivariate polynomials, and prove several characterizations in the case of skew trees.Comment: 25 pages, 2 figures, Abstract shortened to meet arxiv requirement

A note on cetacean distribution in the Indian EEZ and contiguous seas during 2003-07

Relatively little is known about the distribution of cetaceans in Indian seas due to lack of systematic surveys. For collecting data on species distribution, 35 opportunistic surveys were conducted onboard FORV Sagar Sampada between October 2003 and February 2007 in the Indian EEZ and contiguous seas. In 5,254 hours of sighting effort, a total of 473 cetacean records were made with 5,865 individuals. The occurrence of 10 species from three cetacean families was confirmed. The Indo-Pacific bottlenose dolphin was the most frequently sighted species, whereas the spinner dolphin was dominant in terms of abundance. Long-beaked common dolphins, Indo-Pacific hump-backed dolphin and sperm whales were also recorded at frequent intervals. Cetaceans were found to have a wide geographical distribution in the Indian EEZ and contiguous seas. High abundance and species richness were recorded in the Southeastern Arabian Sea and southern Sri Lankan waters. From the information collected during the present study, the platform of opportunity has proved to be a useful means for cetacean surve

Indian Efforts on the Inventorization of Marine Mammal Species for their Conservation and Management

The present study is the first attempt to use molecular tools for identification of marine mammals in India. The objective was to develop a database of genetic sequences for future marine mammal research in addition to confirming the species identity of cetaceans and dugongs using a molecular approach. Partial sequencing of mitochondrial DNA loci was carried out in accidentally caught/stranded specimens of Spinner dolphin (Stenella longirostris), Pantropical spotted dolphin/bridled dolphin (Stenella attenuata), Bottlenose dolphin (Tursiops aduncus), Long-beaked common dolphin (Delphinus capensis), Indopacific humpbacked dolphin (Sousa chinensis), Risso’s dolphin (Grampus griseus), Finless porpoise (Neophocaena phocaenoides), Sperm whale (Physeter macrocephalus), Blue whale (Balaenoptera musculus), Bryde’s whale (Balaenoptera edeni) and Dugong (Dugong dugon). Molecular identification of species was done by phylogenetic reconstruction of the sequences using portals GenBank and DNA Surveillance. Apart from ratifying their morphological identification, the analysis was able to distinguish specimens that otherwise, could not have been identified using conventional approaches. Phylogenetic analysis of the Sousa-Stenella-Tursiops-Delphinus group indicated more or less robust monophyly for all species in this complex, except Delphinus capensis. A sister-group relationship for Sperm whales and Baleen whales was evident, that would place the former closer to the latter than to any other group of toothed whales

Observations on incidental catch of cetaceans in three landing centres along the Indian coast

A short term survey to quantify the number of marine mammals incidentally caught, and interviews to gain perceptions of local fishers towards issues of by-catch, were conducted. A total of 44 cetaceans were recorded as incidental catches at Chennai, Kakinada and Mangalore fishing harbours during 80 days of observation. Six species of dolphins and one species of porpoise were recorded. The spinner dolphin Stenella longirostris was the most frequently caught (38.6%), followed by the finless porpoise Neophocaena phocaenoides (31.8%). Gillnets and purse seines operated from motorised boats accounted for the entire by-catch. It is estimated that 9000–10,000 cetaceans are killed by gillnets every year along the Indian coast. The intricacies and possibilities of reducing cetacean kills by gillnets are discussed in the pape

Stomach contents of cetaceans incidentally caught along Mangalore and Chennai coasts of India

Abstract The stomachs of 32 individuals of seven cetacean species incidentally caught in gill net and purseseine fisheries along Mangalore and Chennai coasts (India) between 2004 and 2006 were examined. The whole stomach (fore-gut, mid-gut and hind-gut) was examined in all cases. Prey remains (666 prey items comprising six species of teleosts, one crustacean and one squid species) were found in the stomachs of eight individuals (the remaining 24 stomachs were found to be empty). All cetaceans were found to feed mostly on teleosts with wide range of trophic levels. Based on an index that included frequency of occurrence, percentage by number and by weight, the oil sardine Sardinella longiceps was the main prey in the sample. Cetaceans appear to favour both pelagic as well as demersal prey, possibly indicating surface and benthic feeding habits

Automatic modulation classification for cognitive radios using cumulants based on fractional lower order statistics

Automatic modulation classification (AMC) finds various applications in cognitive radios. This paper presents a method for the automatic classification using cumulants derived using fractional lower order statistics. The performance of the classifier is presented in the form of probability of correct classification under noisy and fading conditions. Unlike many of the conventional methods, the proposed method does not require a priori knowledge of signal parameters. The proposed method is also more robust to different noises. Simulation results show that the proposed method can achieve better classification accuracy when compared to conventional cumulant based AMC method, in various impulsive noise conditions. 1

Mitochondrial DNA sequencing of cetaceans and dugong from the Indian seas for their conservation and management

Understanding taxonomy is fundamental to conservation efforts of bioresources. The units on which conservation is based are determined largely by species designation. Ambiguous identification of species may lead to erroneous conclusions, which may be more serious than lack of understanding of the population structure and status; for example, conclusions such as loss of genetic variability(e.g., by unwitting extinction of a species).In cetaceans (whales,dolphins andporpoises), morphological features are subtle and difficult to compare because of the rarity of specimens or widespread distributions.Identifying the geographical variants of recognized species of cetaceans is more cumbersome using the conventional approaches and in this context molecular genetics can provide significant contributions to taxonomic understanding of inter and intra-specific variations for conservation and management purposes. Similarly, in dugong,a critically endangered marine mammal, in order to devise adequate conservation andmanagement strategies for the species of concern, it is essential to study the population genetic characteristics of the species throughout the range of its distribution. DNA sequence analysis has become a powerful tool for conservation

MalFake: A Multimodal Fake News Identification for Malayalam using Recurrent Neural Networks and VGG-16

The amount of news being consumed online has substantially expanded in recent years. Fake news has become increasingly common, especially in regional languages like Malayalam, due to the rapid publication and lack of editorial standards on some online sites. Fake news may have a terrible effect on society, causing people to make bad judgments, lose faith in authorities, and even engage in violent behavior. When we take into the context of India, there are many regional languages, and fake news is spreading in every language. Therefore, providing efficient techniques for identifying false information in regional tongues is crucial. Until now, little to no work has been done in Malayalam, extracting features from multiple modalities to classify fake news. Multimodal approaches are more accurate in detecting fake news, as features from multiple modalities are extracted to build the deep learning classification model. As far as we know, this is the first piece of work in Malayalam that uses multimodal deep learning to tackle false information. Models trained with more than one modality typically outperform models taught with only one modality. Our study in the Malayalam language utilizing multimodal deep learning is a significant step toward more effective misinformation detection and mitigation

The first sighting of Longman’s beaked whale, Indopacetus pacificus in the southern Bay of Bengal

Information on at-sea sightings of beaked wholes are rare from the Indian and Sri-Lankan waters because of the relative rarity of vessels working in deep oceans where these species are encountered. A recent survey onboard FORV ‘Sagar Sampada’ brought out the first confirmed sighting of live animals of Longman’s beaked whole. Indopacetus pacificus from the southern Bay of Bengal. The details of the sighting, illustrated with photographs are presented in this note