Record size black marlin, Makaira indica (Cuvier, 1832) landed at Bhimilipatnam, Andhra Pradesh

A gigantic black marlin, Makaira indica measuring 4.3 m in length and weighing around 450 kg was landed at Bhimilipatnam beach landing centre and brought to Visakhapatnam Fishing Harbour

Age, growth and population structure of the yellowfin tuna Thunnus albacares (Bonnaterre, 1788) exploited along the east coast of India

Lengths measurements of 6,758 yellowfin tuna (Thunnus albacares), landed by hook and line operators off eastern Indian coast were taken (20–185 cm FL) from 2003 to 2009. Age and growth were estimated using length based methods. The von Bertalanffy growth parameters estimated were L∝ = 197.42 cm, annual K= 0.30 and t0= -0.1157. Mortality estimates were M= 0.48 and Z= 0.71 and F= 0.23 with the exploitation ratio E= 0.32. Growth was rapid during the initial years when the annual growth increment was as high as 36.6 cm during the first year then which to as low as 3.3 cm in the tenth year. The fish attained a fork length of 56.2 cm at the end of one year. Size at maturity (87.5 cm) corresponded to an age of 1.7 years and the oldest individual in the sample was 9+ years (186 cm). The annual mean lengths varied from 80.6 cm to 115.3 cm with an average mean length of 101.9 cm. The fishery comprised of mostly adults with 64% comprising of fishes larger than size at first maturity

Feeding strategies and diet composition of yellowfin tuna Thunnus albacares (Bonnaterre, 1788) caught along Andhra Pradesh, east coast of India

The food of yellowfin tuna, Thunnus albacares caught by longlines off the east coast of India was studied in detail. Contents of 146 non-empty stomachs were analysed for the Index of relative importance (IRI) and prey specific abundance. T. albacares caught by the longline were found to be non-selective generalist feeders, foraging on micronektonic, pelagic or benthic organisms available in the epipelagic waters. Teleost fish, crabs, squids and shrimps were the major component of food items. Priacanthus hamrur was the most preyed upon fish with a high IRI (40.5%) followed by the swimming crab Charybdis smithii (23.9%), the squid Sthenoteuthis oualaniensis (15.5%) and prawn Solenocera hextii (10.3%). Being a large pelagic predator, it formed an important link in the food chain of the ocean system and also formed a good collector of the less exploited micronekton organisms of the deep scattering layer (DSL)

An Effective Deep Learning Based Multi-Class Classification of DoS and DDoS Attack Detection

In the past few years, cybersecurity is becoming very important due to the rise in internet users. The internet attacks such as Denial of service (DoS) and Distributed Denial of Service (DDoS) attacks severely harm a website or server and make them unavailable to other users. Network Monitoring and control systems have found it challenging to identify the many classes of DoS and DDoS attacks since each operates uniquely. Hence a powerful technique is required for attack detection. Traditional machine learning techniques are inefficient in handling extensive network data and cannot extract high-level features for attack detection. Therefore, an effective deep learning-based intrusion detection system is developed in this paper for DoS and DDoS attack classification. This model includes various phases and starts with the Deep Convolutional Generative Adversarial Networks (DCGAN) based technique to address the class imbalance issue in the dataset. Then a deep learning algorithm based on ResNet-50 extracts the critical features for each class in the dataset. After that, an optimized AlexNet-based classifier is implemented for detecting the attacks separately, and the essential parameters of the classifier are optimized using the Atom search optimization algorithm. The proposed approach was evaluated on benchmark datasets, CCIDS2019 and UNSW-NB15, using key classification metrics and achieved 99.37% accuracy for the UNSW-NB15 dataset and 99.33% for the CICIDS2019 dataset. The investigational results demonstrate that the suggested approach performs superior to other competitive techniques in identifying DoS and DDoS attacks

Induction of division and differentiation of somatic embryos in the leaf epidermis of Gaillardia picta

Somatic embroys and subsequent plant regeneration were obtained from isolated leaf epidermis of Gaillardia picta. Abaxial and adaxial epidermal peels (monolayer) from 45 days old aseptic seedlings were isolated and segments measuring 5 mm × 3 mm were cultured on B5 basal medium supplemented with various growth regulators such as naphthaleneacetic acid or indolebutyric acid and benzylaminopurine or kinetin. Within 12 h of culture the epidermal cells showed receding of cytoplasm from the walls. After 48 h of incubation 3 or 4 localized zones, each consisting of 3-8 cells that accumulated cytoplasm and stained densely, were observed. Mitotic divisions occurred in these zones on day 3 of culture and localized masses of callus were observed in 95% of the cultures after 10 days. In another 5 days, the callus differentiated somatic embryos or roots, depending on the growth regulators and their concentration in the medium

Low Temperature Plasma Nitriding of Low Alloy Steel for the Enhancement of Hardness

The present concerns surface modification of low alloy CrMoV steel by following the route of plasma nitriding for the improvement of hardness. Plasma nitriding was performed at a low temperature of 450 oC. The maximum hardness at this lower temperature was found to be ∼1270 Hv after nitriding. At 550 oC though the hardness improvement near the surface region was similar but the core hardness was reduced. XRD studies revealed various nitrides of iron (γ′ (Fe4N) and ε (Fe2–3N)) with the ε nitride as the dominant phase. SEM analyses revealed the surface microstructure with almost no white layer. EDS point analyses shown the signature of N on the surface layer. It has been concluded in this study that the hardness of 90CrMoV8 steel can be improved significantly even at a low temperature of 450 oC without any of risk of the loss of core hardness

Low-temperature plasma nitriding of martensitic stainless steel

This study presents the plasma nitriding of Cr–Mo–V tool steel to protect it from environmental degradation. The steel samples after metallographic polishing were nitrided in the glow discharge plasma of N2 and H2 gas mixture (80:20). Nitriding was performed at two different temperatures, a lower temperature of 450 C and the higher temperature of 500 C. The potentiodynamic polarization tests in 3.5% NaCl electrolyte had shown the enhancement of corrosion resistance of steels after nitriding. X-ray diffraction (XRD) studies and scanning electron microscopic analysis coupled with energy dispersive spectroscopic analysis (SEM/EDS) was performed to understand the modification of surface microstructure. XRD analysis of the nitrided steels revealed the presence of γ′- and ε-nitrides of iron, which were responsible for the improvement of corrosion resistance

Effects of plasma nitriding on low alloy Cr-Mo-V steel

In this study the effects on resistance to corrosion of a low alloy steel after plasma nitriding has been reported. Nitriding was performed at a low temperature of 450 °C and also at 520 °C for the same duration of 10 h in the plasma of nitrogen and hydrogen (80:20) gas mixture. Sample holder was biased at -250 V and the working pressure was kept at around 500 Pa. After nitriding the steel samples along with the bare steel were exposed to X-ray diffraction (XRD) to understand the phase formation. For the assessment of corrosion resistance properties potentiodynamic polarization tests of the bare and plasma nitrided steels in 3.5% NaCl electrolyte were performed. Nitriding at 520 °C had shown the best corrosion resistance. However, broad passivation region had been shown after nitriding at 450 °C

Glow discharge plasma nitriding of low alloy steel

Present study concerns with the effect of plasma nitriding on hardness of low alloy steel. Plasma nitriding had been performed at elevated temperature of 500 C which improved the hardness to 1200 Hv. The case depth was found to be 80 mm. With the variation of time the case depth also varied. The plot of the square of the case depth vs. nitriding time and the corresponding line drawn by a linear regression and extrapolation passes almost through the origin. From the plot the nitrogen diffusion co-efficient calculated to be 2.23 10 13 m2/s. The structural and morphological studies have been made by following the X-ray diffraction (XRD) and scanning electron microscopic (SEM) and EDS analyses. XRD revealed the presence of a-Fe, c0 and e phases