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This paper presents a short review of some of the notable contributions by scientists from several parts of the world in furthering our understanding of the seafloor hydrothermal activity on the Indian Ocean ridges (IOR). Studies to date on the hydrothermal plumes and vents on the IOR and the marine sediments around the vents highlight the complex nature of hydrothermal activity on the Indian Ocean ridge system which is characterised by varying spreading rates, differences in the host rock system and perceptible variations in the chemical composition of the hydrothermal fluids. [ABSTRACT FROM AUTHOR]

Background: Management of bacterial wilt of tomato in Ralstonia solanacearum affected soils is a major issue in tomato cultivation in different agro-ecological regions in Kerala state which affects the production and productivity of the crop. To develop a suitable management protocol for this disease, the field experiments were conducted during 2019 and 2020 in a bacterial wilt-sick field at Kerala Agricultural University, Thrissur, Kerala, India. Methods: Twelve different treatments viz. soil application of bleaching powder, soil test based lime application, streptocycline root dip, drenching of copper hydroxide and copper oxychloride at different doses, seed treatment and seedling dip with Pseudomonas fluorescens, drenching of Pseudomonas fluorescens, planting grafted seedlings and different integrations and combinations of the above treatments were assessed for the management of bacterial wilt. Result: The majority of integrations were superior over individual treatments. The higher yield with less disease incidence was obtained from the integration of soil treatment of bleaching powder (15 kg/ha) + soil test based lime application + streptocycline (@ 2 g/10 L) root dip + drenching of copper oxychloride (@ 0.3%) and therefore, this integration protocol is recommended for management of bacterial wilt of tomato in wilt affected soils in Kerala state. [ABSTRACT FROM AUTHOR]

Palar Basin in India’s southeastern margin is an intracratonic rift basin characterized by a very steep continental slope (gradient, 3°–78°). Recently acquired high-resolution swath bathymetry data from the region documented various geomorphic features on the slope of the Palar Basin, and canyons are most prominent among them. Twenty submarine canyons, grouped as the Palar Canyon System (PCS), have been mapped and identified for the first time in this study. The geological element that controls PCS’s development presents a morphological framework for canyons developed in extremely steep continental slopes, which are rare on continental margins elsewhere. In contrast to many other submarine canyons, the short and low sinuosity canyons in the Palar Basin (1) traverse a large fault (escarpment) exposed up to 1300 m high, (2) erode into a relatively steep margin, and (3) create downstream features akin to the subaerial origin. Because of these unusual characteristics, the environment presents a wide range of possibilities to discuss the processes involved in their origin, evolution, the controlling factors, and sedimentary activity. The present-day PCS architecture implies that the early stages of canyon formation were shaped by bottom–up retrogressive landslides initiated from the disintegrative failures in the oversteepened slope. The evolution of PCS corresponds to the orientation and relative displacement of the fault escarpment, where the movement of the fault generates canyon activity in response to maintaining slope equilibrium. In addition to the fault movement, downward eroding gravity flows and failures along the flanks aid in the canyon shaping processes. For canyons truncated by a large fault, we propose an upslope/bottom–up model of canyon formation that initiates near the steep fault escarpment and incises downslope and propagates upslope to breach the shelf edge. PCS also comprises ellipsoidal depressions and asymmetric bedforms at the downstream reaches of the canyons, classified as “plunge pools” and “mega dunes,” respectively. Seven plunge pools (> 65 m deep) formed at the mouth of some of the canyons are interpreted to reflect the impact of confined high momentum gravity flows, whereas the wave train of mega dunes extending for 10 km opposite to the mouth of a canyon points to the activity of repeated hydraulic jumps in the region. [ABSTRACT FROM AUTHOR]

Newly acquired high resolution multibeam bathymetry data collected from Eastern Arabian Sea show the presence of two distinct, isolated seamounts (~27 km apart) in the flat Arabian Basin, west of Laccadive- Chagos Ridge. The seamount S1 with a relief of 1980 m from the adjacent seafloor has a linear ridgelike shape with NNE-SSW trend and is associated with craters and knolls near its base. Seamount S2 with a relief of 1830 m is conical in shape with steep slopes. Seismic characteristics imply that these two seamounts are extrusive volcanic features covered by thick pile of sediments along the flanks. The evolutionary history of the Arabian Basin and the tectonic fabric of the study area suggest that emplacement of the identified seamounts might be due to the Réunion hotspot volcanism. [ABSTRACT FROM AUTHOR]

The western continental margin of India and the adjacent deep ocean basins were formed by break-up and separation among India, Seychelles and Madagascar since the Late Cretaceous. The initial India-Madagascar separation and the subsequent India-Seychelles separation are believed to have been caused by the Marion hotspot at ~90 Ma and the Réunion hotspot at ~68.5 Ma, respectively. These geodynamic events resulted in the formation of several bathymetric highs that probably represent imprints of these volcanic events. In the present study these bathymetric high features were mapped comprehensively to understand their morphotectonic characteristics, using a fresh set of multibeam bathymetry, sea-surface gravity and magnetic anomalies, complemented by the available multichannel seismic reflection sections. A high-resolution bathymetric map of the southwestern continental margin of India and the adjoining deep offshore regions has been generated to decipher detailed morphological configuration and distribution of prominent undersea bathymetric features. We also carried out detailed morphometric analysis of these features to deduce the morphological parameters. A total of 33 individual bathymetric high features were identified and classified as seamounts, hills, knolls, guyots and plateaus based on the standardization of undersea feature names published by Intergovernmental Oceanographic Commission (IOC) and International Hydrographic Organization (IHO) in 2013. Multichannel seismic reflection, sea-surface gravity and magnetic data were used to describe the sub-seafloor configuration and qualitative interpretation of the geophysical signatures associated with the bathymetric highs. Interpretation of the multichannel seismic reflection sections suggest that some of these identified features are extrusive in nature, while others are intrusive. These features are associated with characteristic gravity highs superimposed over regional negative anomalies and complex negative and positive magnetic anomalies. The study results suggest that the genesis of the bathymetric highs mapped in the study area could be attributed to the hotspot volcanism, caused by the Marion or Réunion hotspots. We infer that the features in the southwestern continental margin of India closer to the Alleppey-Trivandrum Terrace Complex might have been created by the Marion hotspot volcanism, while those in the Laccadive Basin and eastern sector of the Laccadive Plateau might have been formed by Réunion hotspot volcanism. [ABSTRACT FROM AUTHOR]

The argument that biological systems are too "warm and wet" to support quantum effects is becoming increasingly antiquated as research in the field of quantum biology progresses. In fact, not only is it becoming apparent that quantum processes may regularly take place in biological systems, but these processes may underlie the mechanisms of consciousness and propel our models of conceptualizing the human brain into the next era of scientific understanding. The phenomena of consciousness have allured scientists and philosophers for thousands of years, while a precise technical understanding has remained elusive. If possible, developing this understanding will likely be one of humanity's greatest achievements. Knowing the fundamental processes that create conscious experience has far-reaching implications, from the potential birth of true artificial intelligence to a better understanding of mental health disorder etiologies and treatments. One major challenge in the mental health professions, and, ultimately, in empathy of any kind, is being able to see from and appreciate another person's unique, subjective experience. Discoveries in the field of consciousness could help bridge this gap. [ABSTRACT FROM AUTHOR]

In this letter we consider dipole-mediated correlations between DNA and enzymes in the context of their water environment. Such correlations emerge from electric dipole-dipole interactions between aromatic ring structures in DNA and in enzymes. We show that there are matching collective modes between DNA and enzyme dipole fields, and that a dynamic time-averaged polarization vanishes in the water dipole field only if either DNA, enzyme, or both are absent from the sample. This persistent field may serve as the electromagnetic image that, in popular colloquialisms about DNA biochemistry, allows enzymes to “scan” or “read” the double helix. Topologically nontrivial configurations in the coherent ground state requiring clamplike enzyme behavior on the DNA may stem, ultimately, from spontaneously broken gauge symmetries. [ABSTRACT FROM AUTHOR]

Oxidative stress is a pathological hallmark of neurodegenerative tauopathic disorders such as Alzheimer's disease and Parkinson's disease-related dementia, which are characterized by altered forms of the microtubule-associated protein (MAP) tau. MAP tau is a key protein in stabilizing the microtubule architecture that regulates neuron morphology and synaptic strength. When MAP tau is degraded in tauopathic disorders, neuron dysfunction results. The precise role of reactive oxygen species (ROS) in the tauopathic disease process, however, is poorly understood. Classically, mitochondrial dysfunction has been viewed as the major source of oxidative stress and has been shown to precede tau and amyloid pathology in various dementias, but the exact mechanisms are not clear. It is known that the production of ROS by mitochondria can result in ultraweak photon emission (UPE) within cells. While of low intensity, surrounding proteins within the cytosol can still absorb these energetic photons via aromatic amino acids (e.g., tryptophan and tyrosine). One likely absorber of these photons is the microtubule cytoskeleton, as it forms a vast network spanning neurons, is highly co-localized with mitochondria, and shows a high density of aromatic amino acids. Functional microtubule networks may traffic this ROS-generated endogenous photon energy for cellular signaling, or they may serve as dissipaters/conduits of such energy to protect the cell from potentially harmful effects. Experimentally, after in vitro exposure to exogenous photons, microtubules have been shown to reorient and reorganize in a dose-dependent manner with the greatest effect being observed around 280 nm, in the tryptophan and tyrosine absorption range. In this paper, recent modeling efforts based on ambient temperature experiment are presented, showing that tubulin polymers can feasibly absorb and channel these photoexcitations via resonance energy transfer, on the order of dendritic length scales and neuronal fine structure. Since microtubule networks are compromised in tauopathic diseases such as Alzheimer's and Parkinson's dementias, patients with these illnesses would be unable to support effective channeling of these photons for signaling or dissipation. Consequent emission surplus due to increased UPE production or decreased ability to absorb and transfer may lead to increased cellular oxidative damage, thus hastening the neurodegenerative process. [ABSTRACT FROM AUTHOR]

Multibeam echo-sounder (MBES), sub-bottom profiler, singlebeam tracks and public-domain bathymetry geophysical datasets were analyzed in a Geographic Information System (GIS) for accuracy assessment and further used to update the previous map (Curray et al. Mar Pet Geol 19: 1191-1223, ) of submarine channel-levee systems in the eastern Bengal Fan near the Andaman region. Comparative analysis of singlebeam with MBES indicated 2.8 % of root-mean-square difference in bathymetry, and could clearly bring out distinct submarine channel profiles. The channel map revealed that the previously named E6 [updated as E7(1a)] and E7 [updated as E7(1b)] channels emanate from the middle and lower Bengal Fan, respectively and merge together at 91.28°E, 10.64°N where they form a second order channel [E7(2)] that flows southward along the east of Ninety-east Ridge. Similarly, two first order channels [E6(1a) and E6(1b)] emanate from the lower Bengal Fan which merge together at 88.78°E, 06.92°N to form a second order channel [E6(2)] that flows along the west of Ninety-east Ridge towards the equator. This channel was previously thought to be linked to the middle Bengal Fan. High-resolution MBES tracks over the channel shows extensive meandering patterns with the channel gently deepening and widening towards south. Variations in the morphology and stratigraphy indicate that the E7 channel is characterized by a curvilinear course, with higher observed sinuosity wherever gradient decreases. [ABSTRACT FROM AUTHOR]

A sediment core recovered from the southeastern Arabian Sea off the Indian subcontinent was analysed to understand the distribution of major (Fe, K, Mg, Al, Ca and Sr) and trace elements (Mn, Ni, Cu and Co) as well as their environmental significance. According to the results, variation of Fe, K, Mg and Al during early Holocene period is reflective of the strengthened southwest monsoon and resulting fluvial input of terrigenous materials to the study region. The concentration profile of Ca, Sr and total organic carbon during late Holocene reveals increased productivity and coastal upwelling during recent periods. The profile of redox-sensitive metals indicates the role of terrigenous sources in the variation of these elements apart from the scavenging-releasing effects of Fe-Mnoxides/ hydroxides as well as decrease in oxygen level in sediment-water interface from early Holocene to late Holocene period. The study suggests that two factors are predominantly responsible for observed geochemical variations - terrigenous and biological contribution. [ABSTRACT FROM AUTHOR]

Abstract: An anomalous lateral bathymetric protrusion [Alleppey–Trivandrum Terrace Complex (ATTC)] in the form of two contiguous terrace-like features exists in the mid-continental slope off southwest coast of India. This bathymetric protrusion and a bathymetric notch in the Northern Madagascar Ridge (NMR) have been postulated as conjugate features related to India–Madagascar separation in Late Cretaceous. However, geoscientific studies aimed to understand the crustal structure and genesis of the ATTC or its postulated conjugate region are meagre and ambiguous. In this context, the present study, based on recently acquired as well existing bathymetry, gravity, magnetic and multi-channel seismic reflection data, was carried out to understand the morphotectonic architecture of the ATTC. The bathymetric data suggest an escarpment [Chain-Kairali Escarpment (CKE)] to demarcate the westward limit of the ATTC and another escarpment [Quilon Escarpment (QE)] to demarcate the boundary between the southerly, larger ‘Trivandrum Terrace (TT)’ and northerly, smaller Alleppey Terrace (AT). The multichannel seismic reflection data suggests a block-faulted basement and presence of a nearly N–S trending wide basement high in the central part of the Trivandrum Terrace. Forward modelling of gravity data constrained by seismic reflection information suggests that the crustal structure of the ATTC region is comparable to thinned continental crust. Forward modelling of prominent high amplitude magnetic anomalies suggest that the thinned continental crust of the ATTC region also contains volcanic bodies as intrusives/extrusives. The CKE is inferred to be a sheared continental margin segment along which the SE coast of Madagascar glided past India and the volcanic emplacements in the ATTC region perhaps relates to the Marion Hotspot volcanism. [Copyright &y& Elsevier]

We have done a time series analysis of daily average data of solar wind velocity, density and temperature at 1 AU measured by ACE spacecraft for a period of nine years. We have used the raw data without filtering to give a faithful representation of the nonlinear behaviour of the solar wind flow which is a novel one. The sensitivity of the results on filtering is highlighted. The attractor dimension is estimated for every parameter of the solar wind and it is found that they differ substantially. Hence a chaotic picture for the problem from different angles have been obtained. The calculated Kolmogorov entropies and Lyapunov exponents are positive showing evidences that the complex solar wind near the Earth is most likely a deterministic chaotic system. [ABSTRACT FROM AUTHOR]

The synthesis of “smart” tricomponent amphiphilic membranes containing poly(ethylene glycol) (PEG), polydimethylsiloxane (PDMS) and polypentamethylcyclopentasiloxane (PD5) domains is described. Contact angle hysteresis indicates that in air, the surfaces of such PEG/PD5/PDMS membranes are enriched by the hydrophobic components, PDMS and PD5, while in water, the surfaces are rich in the hydrophilic PEG. The oxygen permeability of a series of membranes with varying Mc,hydrophilic (Mn,PEG=4600, 10,000 and 20,000 g/mol) and varying PEG/PD5/PDMS compositions was studied. Oxygen permeability increased with the amount of PDMS in the membrane. The molecular weight cut-off (MWCO) ranges and permeability coefficients of insulin through a series of PEG/PD5/PDMS(=29/14/57) membranes with varying Mc,hydrophilic were determined. Insulin permeability is directly related to Mc,hydrophilic of the membrane. MWCO studies show that the membranes are semipermeable to, i.e., allow the transport of smaller proteins such as insulin (Mn=5733 g/mol, Rs=1.34 nm) and cytochrome c (Mn=12,400 g/mol, Rs=1.63 nm), but are barriers to larger proteins such as albumin (Mn=66,000 g/mol, Rs=3.62 nm). Implantation of representative membranes in rats showed them to be biocompatible. According to these studies, PEG/PD5/PDMS membranes may be suitable for biological applications, e.g., immunoisolation of cells. [Copyright &y& Elsevier]

Composite magnetic materials have the unique advantage of property modification for tailoring devices for various applications. Rubber ferrite composites (RFCs) prepared by incorporating ferrites in rubber matrixes have the advantage of easy mouldability and flexibility. RFCs containing various loadings of nickel zinc ferrite (NZF) (Ni1−xZnxFe2O4) in a natural rubber matrix have been prepared. The cure characteristics and the mechanical properties of these composites were evaluated. The effect of loading on the cure characteristics and tensile properties were also evaluated. It is found that the loading dependence on the cure time and mechanical properties exhibit an identical pattern. [Copyright &y& Elsevier]

We consider in a quantum field theory framework the effects of a classical magnetic field on the spin and orbital angular momentum (OAM) of a free electron. We derive formulae for the changes in the spin and OAM due to the introduction of a general classical background field. We consider then a constant magnetic field, in which case the relevant expressions of the effects become much simpler and conversions between spin and OAM become readily apparent. An estimate of the expectation values for a realistic electron state is also given. Our findings may be of interest to researchers in spintronics and the field of quantum biology, where electron spin has been implicated on macroscopic time and energy scales. [ABSTRACT FROM AUTHOR]

A letter to the editor related to the endophytic bacteria (EB) is presented.

The southwestern continental margin of India reveals the presence of an anomalous bathymetric high feature located in the mid-continental slope region off Trivandrum. Based on the analysis of the available geophysical data and plate tectonic reconstruction, this feature was interpreted as a scar of India-Madagascar separation, with its conjugate identified on the Northern Madagascar Ridge. Although the conjugate nature of the Alleppey-Trivandrum Terrace Complex and the Northern Madagascar Ridge was postulated, this inference has not yet been evaluated by comparing their geophysical signatures and crustal structure. The present study is aimed to derive and compare the crustal configuration of these two features using an up-to-date compilation of the bathymetry, gravity and magnetic data, and by employing integrated forward modelling of gravity and magnetic anomalies. Our derived crustal models for the Alleppey-Trivandrum Terrace Complex and the Northern Madagascar Ridge suggest that both these features can be explained in terms of thinned continental crust intermingled with volcanic intrusives. The crustal thicknesses of the Northern Madagascar Ridge and Alleppey-Trivandrum Terrace Complex at their conjugate continent-ocean boundaries are ~ 17 km and both these features are associated with high amplitude magnetic anomalies whose genesis is attributed to the volcanism caused by the Marion hotspot activity. Therefore, based on our integrated interpretation of the geophysical data, we support the earlier interpretation on conjugate nature of the Northern Madagascar Ridge and the Alleppey-Trivandrum Terrace Complex that was proposed based on the fitting of shape and size of the bathymetric notch observed in the southeastern continental margin of Madagascar with a bathymetric protrusion observed in the southwestern continental margin of India in the India-Madagascar pre-drift scenario. These features remained as a single unit prior to ~ 88 Ma and subsequently got separated during the India-Madagascar breakup. [ABSTRACT FROM AUTHOR]

It is well-known that there is a close relationship between the supergranules, magnetic field and the Extreme-UltraViolet (EUV) network of the solar atmosphere. We have obtained the network characteristics from the imaging data from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) in the lines He ii 304 Å and C iv 1600 Å. The changes in the network index and contrast with reference to the sunspot cycle are examined for a duration of about 10 years from 2010 to 2020. The cross correlation between network properties and monthly sunspot number are obtained. For the He ii line, the network index and contrast show a negative correlation with the sunspot cycle. This negative correlation is probably related to the anomalous behaviour of the He lines, noticed earlier. The cross correlation of network properties with the sunspot number for the C iv line shows a general positive correlation, which is usually observed in chromospheric and transition region lines. A comparison of the characteristics of the two lines shows that the network index is more than double for the He line while the contrast is almost comparable. These findings can have significance in line emission mechanisms, flux transfer and solar irradiance. [ABSTRACT FROM AUTHOR]

Genome of Alcanivorax sp. IO_7, an alkane degrading deep-sea bacteria isolated from hydrothermally-influenced Southwest Indian Ridge was sequenced and analysed. Genomic data mining revealed gene clusters for degrading n -alkane and cycloalkanes, including biosurfactant production. The strain was shown to grow on hexadecane as its sole carbon source, supporting the findings of genomic analysis. Presence of cyclohexanone monooxygenase among genomic islands suggest that this strain may have used gene transfer to enhance its hydrocarbon degradation ability. Genes encoding for heavy metal resistance, multidrug resistance and multiple natural product biosynthesis crucial for survival in the hydrothermally influenced deep sea environment were detected. In our comparative genome analysis, it was evident that marine Alcanivorax strains contain a suite of enzymes for n -alkane and haloalkanoate degradation. Comparative genome and genomic synteny analysis provided insights into the physiological features and adaptation strategies of Alcanivorax sp. IO_7 in the deep-sea hydrothermal environment. • Genome sequence of alkane degrading Alcanivorax from hydrothermally-influenced SWIR. • Genomic islands indicate use of gene transfer to enhance hydrocarbon degradation. • Genes for heavy metal-, multidrug-resistance, multiple natural product biosynthesis. • Adaptation strategies of Alcanivorax sp. in the deep-sea hydrothermal environment. [ABSTRACT FROM AUTHOR]

The interest in deep-sea mineral resources has surged recently, driven by the increasing need for metals and the global push for sustainable, low-carbon energy sources under the 'blue economy' framework. The deepsea minerals include polymetallic nodules, cobalt-rich Fe-Mn crusts, and polymetallic sulphides, which contain high amounts of copper, nickel, cobalt and other valuable metals. These mineral deposits are often associated with unique and fragile ecosystems, which necessitates the development of mining technologies with minimal environmental impact. Here, we review the key deep-sea minerals, their resource potential, exploration aspects and the need for sustainable extraction, with a particular focus on India's exploration activities. [ABSTRACT FROM AUTHOR]

The Bengal Fan, the largest submarine fan in the world, spanning the whole Bay of Bengal resulted from the India-Asia collision event and subsequent Himalayan orogeny. It is a significant depositional feature formed by the major river systems: the Ganges and Brahmaputra. Previous studies revealed the occurrence of an extensive channel-levee system in the Bengal Fan through various marine geoscientific investigations. In the present study, we have successfully mapped a submarine channel-levee segment in the lower Bengal Fan using hull-mounted multibeam bathymetry data collected for the first time. In addition, we conducted a pioneering study of a submarine channel segment using an Autonomous Underwater Vehicle (AUV) within the identified channel. The identified channel, characterized by moderate sinuosity, maintains a smooth morphology throughout its course, with the channel incision increasing towards the lower course. The microbathymetric observations revealed fine-scale features such as mass wasting, sediment waves and scour/depressions indicating the direct interaction between turbidity currents and the channel floor. The newly identified channel is proposed to result from the channel bifurcation of the previously identified channel W6 described by Curray et al. (2003). This study showcases the importance of near-bottom observations in complex submarine channel-levee systems for a better understanding of the formation processes involved in such systems. [ABSTRACT FROM AUTHOR]

Abstract A gravity core retrieved from the southern Bay of Bengal (BoB) was studied to determine the sources of sediments and factors controlling their distributions during the Late Quaternary. The parameters used for this study was sediment grain size, organic carbon, clay mineralogy and environmental magnetic properties. Radiocarbon ages of sediments indicate that the 3.06 m long sediment core covers a period since ~45 cal kyr B.P. The sediments deposited before ~14 cal kyr B.P. were clayey silt with higher magnetic susceptibility (MS) values (av: 26 × 10−8 m3 kg−1) and those deposited after ~14 cal kyr B.P. were sandy silt with lower MS values (avg: 13 × 10−8 m3 kg−1). The latter period (after ~14 cal kyr B.P.) indicated high energy turbidites from the Himalayan Rivers into the BoB due to the strengthening of summer monsoon and ice-melt in the Himalayas. Higher smectite and lower illite contents during the last glacial maximum (LGM) reflected low sediment supply from the Ganges-Brahmaputra River System (GBRS) and higher illite and lower smectite during ~14 cal kyr B.P. indicated increased sediment supply from GBRS during this interglacial period. The magnetic grain size of sediments deposited from ~15 cal kyr B.P. was more fine-grained at the start of the Bølling-Ållerød (B-A) event and coarse-grained during ~13 cal kyr B.P. (Younger Dryas event). Fine-grained magnetic minerals also showed a peak at ~11 cal kyr B.P. along with higher summer solar insolation. The down-core variations in sediment grain size, magnetic properties and clay minerals were interpreted in relation to the significant changes in sources of sediments in the BoB during different climatic events. The changing sediment supply in the BoB was due to the combined influence of ice-melt by increased solar insolation and intensification of summer monsoon over Himalaya. Increase of fine-grained magnetic minerals at ~15 cal kyr B.P. and coarser sediment fraction at ~14 cal kyr B.P. indicated time gap between intensification of summer monsoon and ice-melt over Himalaya, respectively. The trend of the magnetic grain size record seems to be modulated by orbital-scale variations in June insolation, which coincides with the summer monsoon variations also. These observed climatic variations are correlating well with the climate changes of the Northern Hemisphere during the Late Quaternary. Graphical abstract Unlabelled Image Highlights • Sediment grain size, clay mineralogy and rock magnetic properties distributions in a sediment core from the Bay of Bengal. • The sediments deposited before ~14 cal kyr B.P. are distinct from those deposited after ~14 cal kyr B.P. • The changing sediment supply was due to the strengthening of summer monsoon and ice melt in the Himalaya. • The smaller magnetic grain sizes during periods of strong summer monsoon are products of increased chemical weathering. [ABSTRACT FROM AUTHOR]

Eight African marigold (Tagetes erecta L.) genotypes (5 F1 hybrids, 2 varieties and 1 local collection) were evaluated for yield and resistance to bacterial wilt during June to September 2016 in a bacterial wilt sick plot at Agricultural Research Station, Mannuthy. F1 hybrids evaluated were Maria 91, Rupa, Sakura 031, Royal Orange and P-4. Along with the F1 hybrids, two varieties from IIHR viz., Arka Agni and Arka Bangara 2, and one local collection, M-1, were also included in the study. The genotypes showed wide variation with respect to plant characters, floral characters, yield and yield attributes as well as bacterial wilt incidence. The genotype'P-4' was found promising with good plant characters, high yield (1.036 kg/plant), and large sized flowers but was moderately susceptible to bacterial wilt. The local collection 'M-1' was found completely resistant to bacterial wilt but had low yield (0.234 kg/plant) and poor quality flowers, while the F1hybrid 'Sakura 031' was found highly susceptible with 100 per cent wilt incidence. [ABSTRACT FROM AUTHOR]

Diseases caused by viruses are a major problem in bitter gourd throughout India, causing considerable yield loss. Use of host plant resistance is the cheapest and effective disease management strategy. In the present investigation 50 genotypes of Momordica charantia var. muricata along with 3 susceptible check varieties viz., Preethi, Priyanka and Pusa purvi were screened against viral infections under natural epiphytotic conditions during the years 2016 and 2017. Both per cent disease severity (PDS) and area under disease progress curve (AUDPC) were calculated to assess and categorize the disease resistance in bitter gourd. They showed varying degrees of response against viral infection when categorized on 0-5 scale. Among 53 accessions evaluated, five were found resistant, nine moderately resistant, 25 moderately susceptible, 11 susceptible and two highly susceptible. None of the genotypes recorded immune response. The resistant genotypes can be utilized in breeding programme to evolve resistant varieties. [ABSTRACT FROM AUTHOR]

The stable continental margins, such as the Eastern continental margin of India, are an important archive of the past climates, sedimentation, and glacio-eustatic sea-level oscillations. This study uses high-resolution bathymetry data to report palaeoshorelines in the Visakhapatnam Bay basin at 90 m and 105 m water depths. The trend of the shorelines is continuous and very distinct and provides a valuable base map for the systematic collection of sediment samples to confirm the periods of sea-level rise, post the Last Glacial Maximum (LGM) in the Indian continental margin (LGM spans ca. 29–19 ka BP interval). The newly collected single-beam and multibeam echosounder data indicate that the linear trending features running parallel to the coast are palaeoshorelines representing different phases of the sea-level transgression. We believe that the palaeoshorelines at 90 m and 105 m are a result of a sluggish post-glacial sea-level transgression during the late Pleistocene. [ABSTRACT FROM AUTHOR]

The topographic fabric of the rift valley floor has been analyzed using the multibeam echosounder data obtained by the autonomous underwater vehicle (AUV) Abyss at two locations over a short segment of the slow-spreading Central Indian Ridge between 10°18′ and 10°57′S. The region is influenced by hydrothermal venting in the near vicinity. Two AUV dives D51 and D52 were performed over this segment at two locations that are 30 km apart and covered 5 km2 and 8 km2 seafloor area, respectively. The dive D51 covered the off-axis part of the rift valley floor in the middle part of the segment, and the dive D52 is located near to the non-transform discontinuity that covered the terminal part of an oceanic core complex (OCC). High-resolution seafloor topography as revealed by the AUV-mounted multibeam echosounder system brought out several micro-bathymetric fabric features such as a lava lake, a cratered volcano, an OCC, and the foot wall volcanic complex at the distal part of the OCC. The valley floor imaged in the D51 is marked by a lava flow encompassing an area of 1 km2 and a volcano in the NE corner. The volcano has a diameter of about 800 m with an elevation of about 200 m from the adjacent seafloor, and the partially mapped volcano crater has a relief of about 60 m. A prominent linear fissure running parallel to the ridge axis has been identified; this feature joins with the volcano. Analysis of AUV-mounted CTD data indicated three distinct temperature spikes ranging 0.009 to 0.013 °C in the region of dive D51. The observed temperature spikes appear to be related to the linear fissure on the seafloor and probably represent leaky venting of fluids from the fissure. With respect to the dive D52, the foot wall volcanic features associated with the OCC are prominent. The volcanic seafloor feature covered an area of 3.45 km2 and is conspicuous with rugged topographic fabric at the base of the OCC. These inferences and the morphotectonics of the rift valley floor as revealed by the AUV data suggest moderate hydrothermal venting in this segment of the slow-spreading Central Indian Ridge. [ABSTRACT FROM AUTHOR]

The effects of a magnetic field on the energy and on the spin of free electrons are computed in the theoretical framework of quantum field theory. In the case of a static moderate field and with relatively slow electrons, the derived formulae are particularly simple. A comparison with the approaches of classical physics and of quantum mechanics shows essential differences and important analogies. The relevance to the magnetic effects of the initial polarization components of the electron states and the possible existence of special values of these quantities are discussed in the final conclusions, which might be useful to explain recent experiments on quasi-free electrons in chiral systems in biology. [ABSTRACT FROM AUTHOR]

Iron is a limiting nutrient in the marine biogeochemical cycle, and hydrothermal processes at mid-ocean ridges are well-known as one of its sources to the water column. However, a major portion of the hydrothermal iron is precipitated near the source and plays an essential role in oceanic elemental cycling. Here, we carried out a detailed study on the geochemical characteristics of Fe, using a sequential chemical extraction protocol, in a short sediment core collected from the eastern Southwest Indian Ridge (SWIR) to understand the iron association in individual mineral phases. Major and trace and rare-earth element concentrations, positive europium anomaly, and rare-earth fractionation show that the source components in the sediment core are composed of biogenic, local mafic, ultramafic, and hydrothermal origin. Solid-phase Fe speciation results indicate that >60% of Fe is associated with the Fe-oxides phase and indicate the hydrothermal plume particulates settled from the water column. A relatively low concentration of Fe associated with the pyrite and silicate (FeRes) phase suggests an erosion of sulphide and silicate minerals from the nearby vent field. The down-core variation reflects the transformation of primary ferrihydrite to more stable oxide mineral goethite/hematite and, to some extent, the formation of silicate minerals. [ABSTRACT FROM AUTHOR]

Analysis of high-resolution multibeam bathymetry, sub-bottom profiles, and multichannel seismic reflection data provides a novel understanding of a large-scale submarine landslide in the Cochin offshore region, southwestern continental margin of India. This massive submarine landslide is referred to name as the "Cochin slide". The Cochin slide exhibits a U-shaped slide scar with an average gradient of ~ 2°, which opens in the NNE-SSW trend in the lower slope and Laccadive Basin. The slide scar has a width of ~ 46 km and a total perimeter length of ~ 60 km, estimated with a volume of ~ 240 km3 excavated from this region. A non-sinuous channel with a length of ~ 36 km and having incisions varying from ~ 140 to 40 m from head to toe has developed within the slide scar. The submarine channel might have formed after the slide event facilitating channel incisions in the upper slope. The mass transport deposits associated with the slide have distributed over a wide area (~ 5700 sq. km.) in the lower slope and Laccadive Basin, with a maximum run-out length of ~ 138 km. The preconditioning factors or trigger mechanisms for the Cochin slide could not be precisely established yet. However, sedimentation during different geological times and the occurrence of weak layers might have contributed to the slope instability. The morphology of the Cochin slide, its correlation with the extensive faulting in the continental shelf-slope province, the presence of structural elements, and records of previous earthquakes suggest that the tectonic/geological processes strongly influence the triggering of the slide. [ABSTRACT FROM AUTHOR]

The sediment core (MGS11/02), collected from the lower boundary of the Bay of Bengal (BoB) oxygen minimum zone (890 m) is studied to understand the influences of summer monsoon variations on the terrigenous sediment influx and its relation to bioproductivity and early diagenetic changes in the southwest BoB during the Late Quaternary. The high content of terrigenous controlled metals increased, kaolinite/chlorite increased, and K/Rb decreased after 19 cal kyr BP, indicating a simultaneous increase in the terrigenous influx and intensity of chemical weathering during this period. The variations in summer monsoon and land influx observed in the core sediments are also reflected in the sources of organic matter. High values of δ13C observed at 40 to 19 cal kyr BP suggests higher influence of marine organic matter and/or presence of C 4 terrestrial plant. The negative shift of δ13C between 19 and 6 cal kyr BP could be the result of the change in terrestrial plant biomass to C 3 photosynthesis and increased marine organic matter. Rock magnetic properties and redox-sensitive metals distribution suggests the prevalence of reduced environment during 52 to 19 cal kyr BP and oxic condition during 19 cal kyr BP to present. The low sedimentation during glacial period allowed sufficient time for pyritization which resulted in the low magnetic signals during 52 to 20 cal kyr BP and led to reducing conditions in the sediment interval. The δ15N values in the core sediments are suggesting the absence of denitrification in the water column during last 52 cal kyr BP. Previous studies suggest that the BoB is a geochemical 'tipping point' because the slight changes in water column denitrification by anthropogenic or climatic impact can accelerate BoB nitrogen contribution to the global nitrogen budget. This study indicates the absence of water column denitrification signals during last 52 cal kyr BP even though drastic climatic changes happened in the BoB in the Late Quaternary. [Display omitted] • The study area experienced drastic climatic changes during the last ~52 cal kyr BP. • These climatic changes are reflected in the influx from land, bioproductivity and early diagenetic changes. • A simultaneous increase in the terrigenous influx and intensity of chemical weathering is observed after ~19 cal kyr BP. • The variations in summer monsoon and land influx are reflected in the sources of organic matter. • δ15N results indicate an absence of denitrification in the water column during the last 52 cal kyr BP. [ABSTRACT FROM AUTHOR]

Climate change has been a key driver throughout human history and has frequently been associated with the rise and fall of civilizations. Holocene settlement changes or population displacements were almost always preceded by changes in climate. A high-resolution sedimentary record from the western Bay of Bengal offers insights to centennial-scale mid- to late-Holocene Indian summer monsoon (ISM) variability and its role in the decline of chalcolithic human settlements on India's Deccan Plateau. Increased erosion in the Indian peninsula during the mid- to late-Holocene, due to aridification and agricultural expansion, is evidenced by higher sedimentation, more magnetic mineral content, coarser magnetic grain size, and increased sand content. The results from mineral magnetic and textural analyses reveal centennial-scale abrupt weak ISM during the Bond events in the core monsoon zone of India. The Deccan Chalcolithic civilizations flourished between ∼4.0–3.0 ka BP owing to the favorable climatic conditions, but most of the settlements were deserted after ∼3.0 ka BP. We argue that the abrupt weakening of ISM during Bond event 2 (∼3.1–2.8 ka BP) caused this collapse of Deccan Chalcolithic. The results from this study together with the published records of number of settlements and summed radiocarbon dates suggest a climate-culture link in the Deccan Plateau. The weak ISM periods in this study are coherent with the records of total solar irradiance and the percentage of hematite-stained grains from the North Atlantic and suggest solar control on these abrupt climatic events. • A high-resolution record of mid – to late – Holocene Indian summer monsoon variability in the core monsoon zone of India. • A general weakening of the ISM and aridification of the Indian landmass is observed during mid – to late Holocene beginning around 5.0 ka BP. • Multiple abrupt weak ISM events of centennial – scale are seen in the mineral magnetic and textural parameters. • The results argue that the abrupt weakening of ISM during Bond event 2 (3.1–2.8 ka BP) caused this collapse of Deccan Chalcolithic civilizations. [ABSTRACT FROM AUTHOR]

The Southwest Indian Ridge (SWIR) is poorly understood in terms of local variability in hydrographical characteristics because of a relative lack of data. Furthermore, previous hydrographic studies in SWIR were restricted to the west of 60°E region. We present a new set of hydrographic data which were collected during a survey for the search of hydrothermal plume/activity in between Mt. Jourdanne and Rodrigues Triple Junction (RTJ) over SWIR. The primary goal of our study is to understand the segment-scale hydrography in and above the SWIR rift valley between 63°E to 69°E, with emphasis on water mass propagation and variability of their physical properties. CTD/Oxygen profiles were examined along a ~650 km distance of SWIR axial valley segments. The properties of Antarctic Bottom Water (AABW) were identified in the rift valley section which passes through deep sills from the Crozet basin. Along the ridge, the physical parameters especially at deep and bottom layer depths have observed gradients formed by the obstruction of flow at sills in the valley, along with a unidirectional density driven flow. • Topography blockage of bottom water movement. • Observed density driven unidirectional flow along the SWIR segments. • Presence of modified AABW in the study region. • Southward propagating NIDW observed west of RTJ. [ABSTRACT FROM AUTHOR]

Through experiments and theoretical analysis, we investigated the similarity of gas dis- charge in low-pressure Argon gaps between two plane-parallel electrodes. We found that the breakdown voltages depended not only on gap length and the product of gas pressure and gap length, but also on the aspect ratio of the gap, i.e. Ub = f(pd; d=r). When we considered similar discharge gaps, the radius r, gap length d and gas pressure p fulfiled the conditions of p1r1 = p2r2 and p1d1 = p2d2. In this situation the reduced field E/p was also constant. The voltage-current characteristic curves of similar gaps were approximately the same, which is a novel experimental result. Comparison of the discharge physical param- eters of the scaled-down gap and prototype gap shows that the proportional relations can be derived from the similarity law. Our experimental results provide some instructions on extrapolating two similar gaps and their discharge properties. Application of the similarity law is straightforward when we scale the discharges up or down if they are too small or large. [ABSTRACT FROM AUTHOR]

• The Integrated geophysical study establishes a clear geometric connection between the major shear zones of SGT and offshore structures of Cauvery basin. • Reactivation of the PCSS leading to moderate intraplate seismicity in the area. The Precambrian basement shear zones played a major role in developing offshore structures that are zones of weakness along the eastern continental margin of India. A compilation and analysis of various geophysical datasets, particularly magnetic, gravity, seismicity and seismic reflection data support a clear geometric connection between the shear zones and offshore structures. The presence of shear zones within the crystalline basement in the continental domain and oceanic domain is demarcated primarily by prominent magnetic lineation. We identified three major magnetic lineaments in the offshore Cauvery basin, which correspond to the Plaghat Cauvery shear system (PCSS) of Southern Granulite terrain (SGT). The faults interpreted in the seismic sections are correlated to the extension of PCSS and indicate the location of reactivation of the shear zones which give rise to considerable intraplate seismicity. The geophysical crustal model shows deep crustal-scale faults associated with the marine prolongation of PCSS. The shear zone extended structures in the offshore might have formed at the breakup stage at the onset of rifting and might be extending up to the continent-ocean transition zone (COTZ). The PCSS partly seems to accommodate the stress created by the northward push of Indian plate against the Asian plate. It is also possible that the shear zone might have extended to the nearby land mass that marks it as one of the principal component in Gondwana reconstruction. [ABSTRACT FROM AUTHOR]

The chromospheric network extended to the transition region as the solar EUV network disperses at the coronal level. The EUV emission lines from the transition region give information about different atmospheric heights. The network properties have been obtained from the daily spectroscopic data from the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO) in two lines He i 584.5 Å and O v 630 Å. The synoptic changes in the line intensity, skewness of intensity distribution, mean contrast and network index with respect to the sunspot cycle were studied for a period of 11 years from 1996 to 2006. We have obtained the cross correlation of the monthly average of these quantities with the monthly sunspot number. The mean intensity and skewness of the two lines generally show a positive correlation with the sunspot cycle. The network contrast and network index of the He i shows a definite negative correlation with the sunspot cycle. The negative correlations shown by the He i line are unexpected which could be due to its anomalous behaviour. There are differences in the behaviour of the two lines regarding the time lag with the sunspot cycle and the magnitude of the correlation which is always higher for the He i line. The results have implications to the studies of solar irradiance, magnetic flux transfer and solar atmospheric dynamics. [ABSTRACT FROM AUTHOR]

Breakdown voltage of a gas is the required voltage to start a discharge or electric arc through the gas. Paschen's law describes the characteristics of gas breakdown voltage between two electrodes. This law states that the Gas breakdown voltage(VB) depends only on the product of gas pressure (p) and gap length(d) between electrodes (VB=f(pd)). In this paper, the effect of electrode separation length(d) and electrode radius (r) on gas breakdown voltage is studied experimentally. A gas discharge system with a large gap length compared to electrode radius is used for the study. Paschen curves are plotted for different electrode separation lengths and electrode radii. It is observed that gas breakdown voltages deviates from Paschen's law and depend on the d/r ratio also in addition to the product of gap separation and pressure, i.e. VB=f(pd,d/r). This relation, already reported in the analyses of micro gap discharge and theoretical studies, is known as modified Paschen's law. In order to experimentally verify the modified Paschen's law in large discharge gaps, many experiments are conducted by varying both electrode separation and electrode radii but keeping the d/r ratio always same. It is observed that for different discharge system geometries, if d/r ratio is same, the break down voltages are same for same pd value. The Paschen's curves are also plotted for different experiments and it is observed that the curves overlap if d/r ratio is set same for all experiments. Thus, the work presented in this paper experimentally verify the modified Paschen's law. [ABSTRACT FROM AUTHOR]

Microtubules are biological protein polymers with critical and diverse functions. Their structures share some similarities with photosynthetic antenna complexes, particularly in the ordered arrangement of photoactive molecules with large transition dipole moments. As the role of photoexcitations in microtubules remains an open question, here we analyze tryptophan molecules, the amino acid building block of microtubules with the largest transition dipole strength. By taking their positions and dipole orientations from realistic models capable of reproducing tubulin experimental spectra, and using a Hamiltonian widely employed in quantum optics to describe light–matter interactions, we show that such molecules arranged in their native microtubule configuration exhibit a superradiant lowest exciton state, which represents an excitation fully extended on the chromophore lattice. We also show that such a superradiant state emerges due to supertransfer coupling between the lowest exciton states of smaller blocks of the microtubule. In the dynamics we find that the spreading of excitation is ballistic in the absence of external sources of disorder and strongly dependent on initial conditions. The velocity of photoexcitation spreading is shown to be enhanced by the supertransfer effect with respect to the velocity one would expect from the strength of the nearest-neighbor coupling between tryptophan molecules in the microtubule. Finally, such structures are shown to have an enhanced robustness to static disorder when compared to geometries that include only short-range interactions. These cooperative effects (superradiance and supertransfer) may induce ultra-efficient photoexcitation absorption and could enhance excitonic energy transfer in microtubules over long distances under physiological conditions. [ABSTRACT FROM AUTHOR]

Highlights • Rapid and broad estimation of bacterial taxonomy and physiology at SWIR. • Hydrothermal sediments at SWIR hosted a diverse microbial community. • Bacterial community in the deep-sea hydrothermal sediment degrade PAHs. • Bacterial community can act as ecological indicator of the metabolic sources. Abstract The Southwest Indian Ridge (SWIR) is one of the least explored mid-ocean ridges and contains a high frequency of hydrothermal vents. We examined the bacterial community structure and metabolic potential of surface sediments collected from a sea mount at 2681 m depth and a ridge-flank at 3776 m in SWIR. High throughput 16S rRNA amplicon sequencing combined with Community Level Physiological Profiling (CLPP) revealed that hydrothermal sediments hosted a diverse microbial community with significant difference in structure and function between seamount and ridge-flank. The ridge-flank community was primarily comprised of facultative chemoautotrophic members of Burkholderiales (43.0%) while copiotrophic members of Alteromonadales (56.9%) and Oceanospirillales (14.6%) were dominant in seamount sample. These results coincided with CLPP of microbial community with higher utilization of carbohydrates such as D-cellobiose, β-methyl-D-glucoside, glucose 1-phosophate and pyruvic acid methyl ester observed in seamount. Culture-dependent approach using array of nutrient media enabled the isolation of heterotrophic genera that exhibited ability to degrade refractory organic matter such as phenanthrene, anthracene, pyrene, fluorene and fluoranthene. These results indicate that bacterial community present in the deep-sea hydrothermal sediment can act as bioreactor for mineralization of refractory organic matter. Thus our study emphasize on the significance of polyphasic approach in comprehensive and rapid assessment of physiological and taxonomic characteristics of the deep seabed bacterial community and further suggested that the bacterial community can act as ecological indicators of the metabolic sources prevalent in the ridge environment. [ABSTRACT FROM AUTHOR]

The marine geophysical investigations carried out in the Eastern Arabian Sea revealed the presence of a bathymetric high feature, referred to as the Sagar Kanya Seamount. The preliminary morphology and geophysical characteristics of this feature were studied along a single transect by earlier researchers, however, a detailed geophysical mapping over the entire extent of this feature is still awaited. The present study aims for such a detailed investigation on the Sagar Kanya Seamount and its adjacent regions using newly acquired high-resolution multibeam bathymetry data, complemented with sea surface magnetic and gravity data. Bathymetric map reveals the presence of well-defined bathymetric high features constituting three seamounts connected with structural high/ridge-like features, together representing a large nearly elliptical bathymetric high complex surrounding a region of nearly flat seafloor, referred to as the Sagar Kanya Bathymetric High Complex (SKBHC). The overall morphology of this feature closely resembles with the shape of a submarine volcanic caldera. The gravity anomalies over this feature are mostly correlatable with topography; elliptical-shaped gravity highs are associated with bathymetric highs and gravity lows are associated with the enclosed flat seafloor. Some magnetic anomalies observed over the SKBHC are correlatable with the topographic highs, while others are observed over the flat seafloor. The magnetic anomalies are interpreted as features of post-caldera volcanism. In view of the proximity of this feature to the Réunion hotspot track, and the tectonic framework of the region, the genesis of the SKBHC is attributed to the Réunion hotspot volcanism. Unlabelled Image • Identified an elliptical bathymetric high complex southwest of the Laccadive Plateau • Reported morphology and geophysical characteristics of the bathymetric high complex • Interpreted the bathymetric high complex in terms of a giant volcanic caldera [ABSTRACT FROM AUTHOR]

The article presents the case of 55-year-old patient diagnosed with a rare intradural benign epitheloid schwannoma of the lumbar spine. Topics discussed include the patient's history of low back pain, histological sections of the patient's disorder and epithelioid schwannomas classified by the World Health Organization.