An Efficient Block-based Image Compression And Quality-Wise Decompression Algorithm

In this paper, we propose a block-based lossy image compression algorithm that makes use of spatial redundancies of neighboring pixels in image data. Compression is achieved by replacing a block of pixels with their statistical mean. The algorithm helps in decompressing the image at different quality levels. Quality matrices constructed from the quantization table of the JPEG baseline algorithm are used to achieve different qualities of the reconstructed data. Experimental results show that the proposed method outperforms existing polynomial-based algorithms both in computation time and complexity

An image compression method based on Ramanujan Sums and measures of central dispersion

This paper introduces a simple lossy image compression method based on Ramanujan Sums cq(n) and the statistical measures of numerical data such as mean and standard deviation. The Ramanujan Sum cq(n) has been used in digital signal processing for a variety of applications nowadays. Some of them include the recently developed image kernels for edge detection, extraction of periodicity from signals, etc. The presented compression algorithm is an extension of the edge detection algorithm using an integer image kernel based on Ramanujan Sums. We propose a block-based compression algorithm that detects edges in the images using this image kernel and then compresses the image by storing kernel operation values, the mean and standard deviation for each block instead of pixel values. The proposed method has the advantage of low computational complexity and shows its ability in fast reconstruction and high compression that can be achieved for different block sizes

State based model of long-term potentiation and synaptic tagging and capture

Recent data indicate that plasticity protocols have not only synapse-specific but also more widespread effects. In particular, in synaptic tagging and capture (STC), tagged synapses can capture plasticity-related proteins, synthesized in response to strong stimulation of other synapses. This leads to long-lasting modification of only weakly stimulated synapses. Here we present a biophysical model of synaptic plasticity in the hippocampus that incorporates several key results from experiments on STC. The model specifies a set of physical states in which a synapse can exist, together with transition rates that are affected by high- and low-frequency stimulation protocols. In contrast to most standard plasticity models, the model exhibits both early- and late-phase LTP/D, de-potentiation, and STC. As such, it provides a useful starting point for further theoretical work on the role of STC in learning and memory

Effect of tropical monsoon on fishery abundance of Indian squid (Uroteuthis (Photololigo) duvaucelii)

Indian squid, Uroteuthis (Photololigo) duvaucelii (Loliginidae) constitute an important component of the inshore cephalopod fisheries along the eastern Arabian Sea. Local environmental variation plays an important role in species–environment interactions in neritic squids, which inhabit nearshore/coastal waters. Such ‘active’ and ‘passive’ responses of squids to environmental changes is crucial in understanding their relationships and influence on the biological processes, distribution and abundance of the fast-growing shortlived coastal loliginids. The empirical relationship between squid abundance and the variability in rainfall and sea surface temperature (SST) were explored in a tropical monsoon fishery. Monthly catch rates (catch per fishing hour) of squids in commercial trawl during 1987–2009 were used as the abundance index. Linear regression models with ARIMA errors were fitted with catch per unit hour time series as dependent variable and rainfall and SST as exogenous variables. While rainfall was observed to have a negative effect on squid abundance, the SST recorded a positive impact. ARIMA models provided satisfactory fit to observed data and forecast of 22 months. Given that the squid life-cycle is a function of their environment, this result is relevant in forecasting squid biomass for themanagement of tropical monsoon fisheries

Experimental validation of periodicity of increment formation in the Statolith of bigfin reef squid Sepioteuthis lessoniana (Cephalopoda: Lolignidae) from tropical Indian waters

Sepioteuthis lessoniana (Lesson, 1830) is a neritic squid that inhabits coral, rocky reefs, seaweed and seagrass beds of the IndoPacific region. Increment validation or the periodicity of increment formation in squid statolith is fundamental for age determination, longevity estimation and life history traits, hence it is critical for fishery management and species conservation. Although studies have established one-increment-per-day hypothesis in neritic squids, it has never been validated for tropical Indian Seas. Squids are the dominant component of fauna in the Indian waters, hence an investigation on the statolith increment formation was undertaken for S. lessoniana, as a representative of Loliginid squids

Genetic cataloguing of Octopus species from coastal waters of Kerala using molecular markers

Octopuses are one of the commercially important fishery resource form the Indian coast and there is a targeted fishery for octopus in many fish landing centres in Kerala. There are lot of taxonomic ambiguities within the octopus species and the accurate identification of species is of prior importance in conserving such vulnerable species. With a view to identify and genetically catalogue the octopus species of Kerala coast, specimens were collected from different landing centres of the region. Molecular characterization was done with partial sequence information of mitochondrial gene Cytochrome C oxidase-I (COI) gene. Total 17 specimens of 7 species were collected from 4 locations and COI sequences were generated (650 bp). 7 species included viz, three ocellate octopus, belonging to the genus Amphioctopus; (Amphioctopus neglectus. A. marginatus and A. rex), two from genus Cistopus: (Cistopus Indicus and C. taiwanicus), one each from Octopus vulgaris and Callistoctopus macropus. Both genus of Cistopus and Amphioctopus showed the intra and inter specific distance ranging from 0.0-1.0 % and 7.0-21.0 %, respectively. Phylogenetic analysis using maximum likelihood approach revealed that all the genera of the family Octopodidae are monophyletic

Assessment of dimorphic growth of the cuttlefish Sepia pharaonis (Cephalopoda: Sepiidae) using cuttlebone markings from the south-eastern Arabian Sea

The pharaoh cuttlefish Sepia pharaonis Ehrenberg, 1831, is one of the most important species exploited along the Eastern Arabian Sea. A study on the relationships between dorsal mantle length (DML) and number of cuttlebone septa (or chambers) and between total body weight and number of cuttlebone septa were carried out in S. pharaonis collected from the south-eastern Arabian Sea. The cuttlefish samples were collected from Cochin Fisheries Harbour (133 males and 67 females). Dorsal mantle length-at-chamber count and weight-at-chamber count were statistically higher in males than in females. The available literature suggests that females of S. pharaonis are heavier than males while males are found to attain greater ultimate lengths throughout the lifecycle. Literature also suggests that the rate of cuttlebone septum formation is the same in both sexes of Sepia species, however in the present study, S. pharaonis males have slightly higher growth rates than females (Fig. 1 & 2). The study indicates that there is considerable scope to use cuttlebone chamber counts as a means of determining actual age of cuttlefishe

Size and weight relationships of the purpleback flying squid, Sthenoteuthis oualaniensis (Cephalopoda: Ommastrephidae), from Arabian Sea

The size and weight relationships and morphometrics of 390 individuals of the purpleback flying squid, Sthenoteuthis oualaniensis, collected from the tropical Arabian Sea were studied. The lengthweight relationship was W = 0. 0320 DML3.0972 for females, W = 0.0318 DML3.1288 for males, and W = 0.0382 DML3.0395 when sexes were combined indicating an isometric growth pattern. Most of the morphometric characters showed a high degree of correlation among the compared characters. The relationships between ten morphometric characters against the dorsal mantle length of both the sexes were analysed and it indicated a very high degree of correlation in females compared to males. Females in the samples were twice the size of males, indicating sexual dimorphism in body siz

Tag-Trigger-Consolidation: A Model of Early and Late Long-Term-Potentiation and Depression

Changes in synaptic efficacies need to be long-lasting in order to serve as a substrate for memory. Experimentally, synaptic plasticity exhibits phases covering the induction of long-term potentiation and depression (LTP/LTD) during the early phase of synaptic plasticity, the setting of synaptic tags, a trigger process for protein synthesis, and a slow transition leading to synaptic consolidation during the late phase of synaptic plasticity. We present a mathematical model that describes these different phases of synaptic plasticity. The model explains a large body of experimental data on synaptic tagging and capture, cross-tagging, and the late phases of LTP and LTD. Moreover, the model accounts for the dependence of LTP and LTD induction on voltage and presynaptic stimulation frequency. The stabilization of potentiated synapses during the transition from early to late LTP occurs by protein synthesis dynamics that are shared by groups of synapses. The functional consequence of this shared process is that previously stabilized patterns of strong or weak synapses onto the same postsynaptic neuron are well protected against later changes induced by LTP/LTD protocols at individual synapses