Eastern Indian Research Articles

Sub‐centennial upper water column structure variability of the tropical Indian Ocean since the Last Glacial Maximum

ABSTRACTThe upper water column (UWC) is involved in the worldwide distribution of heat and nutrients. However, global warming is expected to alter the UWC structure due to temperature‐ and precipitation‐induced stratification. This impact of global warming is comparatively more pronounced in the Indian Ocean. Therefore, to understand the fate of the UWC structure in the future, it is important to comprehend its past variability in the Indian Ocean. To achieve this, we have reconstructed sub‐centennial scale variations in the UWC structure of the tropical central Indian Ocean by using the isotopic composition (δ18O and δ13C) of surface‐dwelling planktic foraminifera Globigerinoides ruber and subsurface‐dwelling Neogloboquadrina dutertrei. The difference in the isotopic composition of the surface‐ and subsurface‐dwelling species (Δδ18Or‐d and Δδ13Cr‐d) was used to understand the UWC structure variability in the tropical central Indian Ocean. We report a deeper mixed layer and thermocline during the last glacial period, followed by a shoaling of the thermocline during the glacial–interglacial transition. The thermocline also deepened during intense boreal summer monsoon events such as in the Bølling–Allerød and early Holocene. Our findings suggest that the tropical Indian Ocean UWC is influenced primarily by the intensity of the monsoon winds. From the comparison of our record with those of the eastern and western Indian Ocean, it is evident that a similar climatic forcing governed the central and eastern regions during the last glacial–interglacial period.

Epidermal Growth Factor Receptor (EGFR) and SMAD4 negatively correlated in the progression of gallbladder cancer in Eastern Indian patients

Background and introductionTwo and half percent of the Indian population suffer from gallbladder cancer (GBC). The primary factors that lead GBC are associated with mutation of several protooncogenes such as EGFR, ERBB2, Myc, and CCND1 along with dysregulation of several tumor suppressor genes such as SMAD4 and CDKN2A. Bacterial infection caused by S.typhi and H.pylori are also hypothesized to be potential factors driving GBC.AimsThis study aims to investigate the molecular mechanisms driving the progression of gallbladder adenocarcinoma in Eastern Indian patients. We specifically focussed on analyzing the mutational status of the KRAS gene, examining the amplification of the ERBB2/Her2-neu gene, and evaluating the expression patterns of six dysregulated genes (CCND1, MYC, EGFR, ERBB2/Her2-neu, CDKN2A, SMAD4). Additionally, we assessed the expression status of TGF-beta, the association between bacterial infections (S. Typhi and H. pylori) and GBC, and the impact of single nucleotide polymorphisms in ERBB2/Her2-neu and CCND1 genes within this population.MethodsSixty-seven samples from GBC-diagnosed patients, 26 other unrelated GBC samples for validation cohort, and 68 gallstone tissue samples were collected for this study. Genomic DNA from normal as well as tumor tissues were isolated, exon 2 and exon 3 of KRAS gene were amplified along, DNA sequenced and analyzed. KRAS codon 12 mutation was detected by allele specific PCR (ASPCR) method. Amplification of UreC A (coding for urease subunit α), VacA (coding for Vacuolating cytotoxin A) and CagA genes (coding for cytotoxin-associated gene A) in H.pylori were amplified using PCR. Similarly, FlicC (coding for flagellin gene C) in S.typhi was amplified using PCR. The ERBB2/Her2-neu SNP I655V, and CCND1 SNP A870G were analyzed using PCR followed by RFLP. Expression studies of CCND1, Myc, CDKN2A, ERBB2/Her2-neu, EGFR, and SMAD4 genes were measured in GBC tumor tissues by sybr green quantitative RT PCR.ResultsThe oncogenes (EGFR and ERBB2/Her2-neu) were statistically significantly overexpressed and the tumor suppressor gene (SMAD4) downregulated in our GBC tumor patient samples. The EGFR and SMAD4 genes were negatively correlated (r = -0.01) in GBC patients and the data is statistically significant and validated through IHC technique. A significant downregulation of TGF-beta had also been observed. Lower frequency (i.e. 11.5%) of KRAS mutation in GBC tumor was observed.ConclusionsEGFR and SMAD4 expression were found to be negatively correlated in GBC tissue samples. ERBB2 overexpression/amplification was observed in 30% of the GBC samples. We also found a low percentage of GBC samples to show KRAS codon 12 mutation in Indian GBC patient population, as had been previously documented in pancreatic cancers.

Pyrogenic PAHs Have Different Biogeochemical Fates in the Eastern Indian Ocean.

Understanding the fate of polycyclic aromatic hydrocarbons (PAHs) in the deep ocean is crucial for elucidating the biogeochemical cycle of organic carbon under anthropogenic influences. In this study, surface sediments were collected from the deep sea of the Eastern Indian Ocean (water depth: 2161-4545 m) and analyzed for 29 semivolatile organic compounds (SVOCs), including parent PAHs and their alkylated derivatives, as well as source biomarkers. The target SVOCs (∑29SVOCs: 23.0-183 ng/g, ∑16PAHs: 11.3-93.3 ng/g) were mainly from pyrogenic sources, namely coal combustion, traffic emissions, and wood burning. The contributions from wood burning and coal combustion exhibited distinct trends with increasing total organic carbon contents, suggesting different dominant biogeochemical behaviors. Major fractions of PAHs from wood burning can be biodegraded or photodegraded, leading to a depletion-dominated fate in the water column. Conversely, PAHs from coal combustion showed an accumulation-dominated fate via their sedimentation due to their persistence and hydrophobicity. This study highlights the distinct biogeochemical fates of PAHs from biomass or fossil fuel combustion in deep oceans and has implications for the marine cycle of refractory organic carbon under anthropogenic impacts.

Optimizing the Use of Flexible Retort Pouches for Production of Ready to Eat Cobia (Rachycentron canadum) Fish Chunks in Curry Medium

Cobia fish chunks in curry medium, a famous North Eastern Indian dish, was developed using Cobia (Rachycentron canadum) fish chunks prepared in a traditional culinary style. The present study was aimed to optimize F0 values for Cobia fish chunks in curry medium using flexible retortable pouches. The product underwent thermal processing at two distinct lethality levels and heat penetration rates, demonstrating equivalent cooling and heating lag effects. The fh values were 15 and 18.5 minutes for the product processed at F0 values of 9.29 and 8.42 minutes, respectively. The total process times were 39.79 and 38.80 minutes, respectively, for the F0 values of 8.42 and 9.29 minutes. Cook values for the processed product were 86.60 minutes for the F0 value of 8.42 minutes and 92.57 minutes for the F0 value of 9.29 minutes. Based on sensory characteristics, the product processed at an F0 value of 8.42 minutes was rated better over a storage period of 90 days.

Micro– and mesoplastic pollution in the surface water and nekton from the eastern Indian ocean: Spatiotemporal variation, correlation and risk assessment

The pollution of micro– and mesoplastic (MMP) in the Eastern Indian Ocean (EIO) remains poorly understood. The present study revealed that MMP abundance in nekton from EIO in 2022 (mean: 2.30 ± 0.39 items individual−1 and 1.81 ± 0.54 items g−1) was significantly higher than that in 2021 (mean: 1.60 ± 0.22 items individual−1 and 0.80 ± 0.13 items g−1). In contrast, MMP abundance in surface water varied insignificantly between 2021 (mean: 0.04 ± 0.01 items m−3) and 2022 (mean: 0.05 ± 0.02 items m−3). The rise in predominant polymers—polypropylene (PP), rayon (RA), and polyester (PES)—in nekton from 2021 to 2022 may suggest increased pollution from face masks and home textiles along coastal regions. Notable spatial variation in PP and RA between the northeastern and southeastern regions was observed only in nekton, suggesting they are better indicators of MMP spatiotemporal variation than surface water. Shadow driftfish ingested more MMPs than purpleback flying squid and mackerel scad, likely due to its deeper habitat. By simultaneously considering color, composition, and shape, integrated MMP analysis showed insignificant correlation between MMP pollution in surface water and nekton, suggesting that nekton may ingest MMPs through multiple pathways beyond surface water. Risk indices for surface water and nekton reached moderate to upper levels globally, emphasizing the need for continued monitoring in the EIO. Epoxy resin, rubber, and PP + acrylic were identified as the most hazardous polymers, providing a valuable basis for developing effective strategies to mitigate plastic pollution.

Exploring the deep water mass turnovers in the Eastern Indian Ocean since the late Oligocene: Significance of ocean gateways and paleoclimate

Tectonically driven adjustments within ocean gateways and their impacts on deep water production, thermohaline circulation, and nutrient distribution are well constrained. With no deep water formation in the modern northern Indian Ocean, this study aims to reconstruct the possible source and pathways of deep circulation since the late Oligocene, altering the water mass properties at study sites in the eastern Indian Ocean. Our benthic foraminifera results suggest that tectonic gateways influenced the deep water masses in the eastern Indian Ocean. Significant changes in deep water masses at the studied sites commenced with a gradual reduction in corrosive deep water in the eastern equatorial Indian Ocean (EIO) due to the inflow of relatively warmer and less corrosive Tethyan Overflow Water (TOW) through the Tethyan Gateway in the late Oligocene (∼24 Ma). The EIO gradually became less corrosive from the late Oligocene to the middle Miocene (∼24 to 14 Ma). This turnover reflects the intrusion of southward-flowing TOW and a reduction in the Antarctic Bottom Water (AABW) between ∼24 and ∼ 14.5 Ma in the Indian Ocean. Hereafter, a significant switch in deep water mass was established, contemporaneous with the expansion of Antarctic ice sheets that led to the enhanced production of cold and corrosive AABW that replaced the warm and less corrosive TOW at ∼14 Ma. Furthermore, between ∼12 and 8 Ma the closure of the Tethys Seaway caused a significant hydrological reorganization, replacing the TOW with the Pacific Deep Water (PDW) and North Component Water (NCW). At ∼8 Ma, the contribution of the PDW diminished and AABW flow increased again after a reduction between 12 and 8 Ma, leading to a gradual increase in corrosive deep water. Since 8 Ma, a circulation pattern resembling the modern framework was established with the intrusion of the North Atlantic Deep Water into the CDW, and this pattern was developed by ∼5.7 Ma. Furthermore, the final closure of the Central American Seaway increased the formation of the NADW and its intrusion into the CDW after ∼3.2 Ma.

Remote Underwater Video Confirms the Presence of Dugongs (Dugong dugon) at Ashmore Reef Australian Marine Park in the Eastern Indian Ocean

Remote Underwater Video Confirms the Presence of Dugongs (Dugong dugon) at Ashmore Reef Australian Marine Park in the Eastern Indian Ocean

Optimal Atmospheric Heat Sources for the Interannual Variability of South Asian Summer Monsoon

AbstractUsing a Green's function‐like approach, this study identifies optimal atmospheric heat sources for the two leading modes of South Asian Summer Monsoon (SASM) interannual variability. Optimal heating for the first mode, characterized by a lower‐level anomalous anticyclone over northern Bay of Bengal (BOB), is distributed over the Arabian Sea and tropical eastern Indian Ocean (EIO)‐Maritime Continent, with cooling over the BOB‐western North Pacific. In contrast, heating over the tropical southwestern Indian Ocean and equatorial Atlantic, along with cooling over the tropical EIO‐western Pacific, optimally drives the second mode, featuring an anomalous anticyclone over central‐northern India. El Niño/Southern Oscillation indirectly influences SASM by triggering heat sources resembling these optimal patterns. Other sea surface temperatures (SSTs), like those over equatorial Atlantic, can also generate similar heating structures, causing corresponding SASM anomalies. This suggests that the impact of SST modes on SASM depends on the similarity of induced heat sources to optimal patterns.

Evaluating Tobacco Cessation Readiness in OPMD Patients Using the Transtheoretical Model in a tertiary care setting in Northeast India

Background: Oropharyngeal cancers pose significant global health challenges and addressing public awareness, early symptoms, and risk factors, alongside promoting tobacco cessation among individuals with potentially malignant oral disorders, is crucial for reducing the disease burden.Objective: Evaluating the degree of public knowledge of oral malignancy & OPMD, initial signs & risk factors amongst patients going to a dental college in North East India, as well as readiness to quit tobacco amongst OPMD patient.Methods: This cross-sectional investigation was undertaken at the Department of Public Health Dentistry, Tertiary care Hospital in Guwahati. 200 participants aged 15-65 years who consented were surveyed using a self-administered questionnaire. Collected data underwent thorough checks for completeness and accuracy. To determine the odd's ratio (OR) and to summarise the data, descriptive & inferential statistics were used. To test the relationship, data were dichotomised. Oral lesions present or absent; behavioural phases were divided into two categories: (preparation + action) & (precontemplation + contemplation). P < 0.05 was used as the statistical significance threshold.Results: Most participants were in the contemplation stage regarding tobacco's risks, neglecting other risk factors like alcohol & inadequate dental hygiene for oral malignancy/OPMD development.Conclusions: The lack of knowledge of oral malignancy & potentially malignant disorders (OPMDs) amongst North Eastern Indian communities, underscores the immediate demand for targeted education and health promotion campaigns. Emphasizing early symptom recognition, risk factors, and prevention measures, tailored to diverse communication preferences, is crucial.

A new species of Hoplostethus from Sumatra, eastern Indian Ocean, with comments on its most similar congeners (Trachichthyiformes: Trachichthyidae).

A new species of the roughy fish genus Hoplostethus, subgenus Leiogaster, is described based on three specimens collected from Sumatra, Indonesia. This species can be distinguished from its congeners by the following characteristics: gular region covered with ctenoid scales; pelvic-fin spine smooth on its anterior edge; head depth subequal or smaller than its length (37.2%-38.6% standard length [SL], or 94.7%-99.2% head length [HL]); pectoral-fin length 35.6%-37.8% SL, reaching beyond a vertical through anal-fin origin; abdominal scutes well developed, 12-16; pectoral-fin rays uniformly black, 17-19; gill rakers on the first arch 6-7 + 1 + 13-14 = 21; pre-dorsal scales 24-27; and pyloric caeca 32. A detailed description is provided along with comparisons with its congeners. Additionally, diagnostic characters of the congeners and literature records of Hoplostethus rubellopterus and Hoplostethus melanopus are discussed.

Structure, Propagation of the 10–25-Day and 30–60-Day Intraseasonal Oscillations and Their Role in Triggering the South China Sea Summer Monsoon Onset

Abstract The onset of the South China Sea (SCS) summer monsoon (SCSSM) is a complex process that involves multiscale variabilities, including the 10–25-day high-frequency intraseasonal oscillation (HISO) and the 30–60-day low-frequency intraseasonal oscillation (LISO) along with the seasonal variation. Using the reanalysis and satellite data during the period of 1979–2020, this study comprehensively investigates how the HISO and LISO trigger the SCSSM onset, which improves the understanding of the abrupt SCSSM onset from the point of intraseasonal view. It is clearly documented that in most years, the abrupt SCSSM onsets are triggered by the first branch of HISO and/or LISO propagating into the northern SCS along their distinctive pathways. The HISOs (LISO) originating from the northwestern Pacific Ocean (tropical eastern Indian Ocean) propagates westward (northeastward) toward central-to-northern SCS. The diagnosis based on the moist static energy (MSE) budget reveals the different governing mechanisms of HISO and LISO propagations. HISO’s westward propagation is favored by the zonal advection of the anomalous MSE by the mean easterly wind. In contrast, the surface turbulent heating by sea surface temperature (SST) is the dominant term for LISO’s northward propagation, followed by the meridional advection of the anomalous MSE by the mean southerly wind. Significance Statement This study provides the comprehensive intraseasonal view of the SCSSM onset, where the respective roles of 10–20-day HISO and 30–60-day LISO in triggering the SCSSM onset are identified and their propagating mechanisms are revealed. The prevailing easterlies in the northwestern Pacific and SST-induced turbulent heat flux in SCS are confirmed as the respective dominant processes governing their distinct propagations. These results improve the understanding of the SCSSM onset and hence have significant implication to the monitoring, simulation, and prediction of SCSSM.

The ENSO-IOD effects on Yellowfin tuna (Thunnus albacares) in Eastern Indian Ocean - Off Coast Java

The ENSO-IOD effects on Yellowfin tuna (Thunnus albacares) in Eastern Indian Ocean - Off Coast Java

Uncovering the hidden architecture of the Rengali Province, eastern Indian shield using high-resolution aero-geophysics, ground-gravity, structure: Insights towards geology and tectonics

The Rengali Province is a shear zone bounded discrete domain of amalgamation among two Archean Cratons viz. the Singhbhum and Bastar cratons and a mobile belt namely Eastern Ghat Mobile belt. Based on geological evidences, it also displays an India-Antarctica connection in the past geological time-slice and supports supercontinental reconstruction. Although, the tectonothermal evolution of this province has been largely probed based on lithological, structural and metamorphic accounts, however, correlative geophysical-geology integration is absent. Hence, we analyze and interpret newly acquired high-resolution aero-geophysical data for the first time. The interpretations of high-resolution aero-geophysics, ground gravity and radiometric anomaly have been connected with geology to provide insights into tectonic evolution. Multi-scale geological-geophysical-structuralanalysis has been employed for understanding the subsurface architecture and contact relationship with the nearby cratons-mobile belt. Based on the aero-magnetic signature, three different zones have been delineated viz. northern, central and southern zones within the Rengali Province. The three zones are characterized by their distinct geophysical fabric and further are correlated with the geology. The gravity anomaly and modeling suggest the presence of a high-density body at mid-upper crustal depth (∼5–10 km). Three major shear zones, viz. the Barakot, Riamal and Kerajang delineate the bounding surfaces of the Rengali Province. However, the current geophysical signature indicate that the western part of the Kerajang Fault zone (KFZ) shares an inter-domain status between the Rengali Province and the Bastar Craton while the eastern part showcases an intra-domain character. Based on the complex series of magnetic fabric and anastomosing geophysical (particularly, magnetic) signature, the Rengali Province (RP) displays a classical signature of multiple accretionary histories supported by various episodic tectono-thermal activities at different time-slices.

Relation of low back pain with lumbosacral transitional vertebrae in Eastern Indian population

Relation of low back pain with lumbosacral transitional vertebrae in Eastern Indian population

Southeastern extension of Singhbhum Shear Zone, Eastern Indian Shield: A detailed appraisal

Trans-crustal, northerly dipping, arcuate Singhbhum Shear Zone (SSZ) constituting the interface of Proterozoic North Singhbhum Mobile Belt (NSMB) and Singhbhum Craton (SC) is established over a strike length of about ∼200 km from Baharagorato Chakradharpur in the west beyond which it bifurcates around the wedge shaped Chakradharpur granite. Based on geological mapping and meso to micro scale structural analysis, present work examines the SSZ’s southeastern extension beyond Baharagora, indicating its southward continuation for about 50 km to Dubukidihi within the NSMB lithopackage. Bangriposi Shear Zone (BSZ) which defines the terrane boundary between the SC and NSMB in this sector, splays towards north as Bangriposi West Shear Zone (BWSZ) and both transects the Dhanjori Basin longitudinally. BSZ and BWSZ are interpreted to be cogenetic with SSZ. NSMB in this area comprises of pelitic and psamopelitic rocks intruded by mafic–ultramafic magmatism and granitoids. Considering a north to south compression regime during accretion of NSMB with SC, the study area, which forms the interface between the craton and mobile belt, is at an acute to obtuse angle with the direction of overall stress field. It is marked by several high strain zones characterized by N-S shear band cleavages with moderate easterly dips, and northerly pitching stretching/mineral lineation. Consistent westerly vergent folds on mylonitic plane and orientation of stretching lineation indicates top to WSW movement in the shear zones. Tectonically interleaved mafic–ultramafic schist within the Romapahari granite are sites of copper mineralization with enhanced nickel concentration pointing towards future exploration sites for epigenetic copper, uranium mineralization which is so characteristic of SSZ.

Distribution Characteristics and Dynamics of Marine Hydrogen in the Eastern Indian Ocean

AbstractThe ocean serves as a significant contributor of atmospheric Hydrogen (H2) with indirect greenhouse effects. However, uncertainties persist regarding internal production and consumption processes of marine H2, as well as controlling factors. Our study examined the spatial distribution and source‐sink dynamics of marine H2 in the Eastern Indian Ocean. H2 concentrations in surface seawater exhibited a range of 2.95–21.96 nmol L−1. High concentrations of H2 were observed in the anoxic water in the Bay of Bengal. Rates of H2 photo‐production and microbial consumption in surface seawater ranged from 1.80 to 17.78 nmol L−1 h−1 and 1.02–9.18 nmol L−1 h−1, respectively. When considering the entire mixed layer, photo‐production contribute to approximately 31%–43% of the total H2 removal, with cyanobacteria potentially serving as another source in the mixed layer. Compared with the sea‐to‐air exchange, microbial consumption was the primary removal pathway of H2 in seawater.

Mental Foramen as a Guide to Establish Sexual Dimorphism among Eastern Indian Population: An Observational Cross-sectional Study on Dry Bones

Abstract Context: The study deals with a role of mental foramen in determining the sexual dimorphism of mandibles as well as generating the sufficient data for the dental surgeons regarding location and measurements of the same. Aims: The aim of the study was to determine the location of mental foramen with respect to the different bony points of mandible and the presence of accessory foramen, if any and to establish sexual dimorphism among mandibles in relation to mental foramen and assessing the role of mento-submental angle for the same. Settings and Design: An observational cross-sectional study was conducted at Medical Colleges of West Bengal. Materials and Methods: Two hundred and eighty dry mandibles were used. Digital images were captured with digital camera after placing the bones in anatomical position for suitable views. Measurements were taken with the help of ImageJ software. Statistical analysis was performed using the SPSS software. Statistical Analysis Used: Measures of central tendency were determined. Significance was tested using the Chi-square test or unpaired Student’s t test, as applicable. Results: Most of the mental foramina were in line with the second premolar tooth or between the first and second premolars. Distance from the alveolar margin and the diameters of foramen were statistically significant among the genders. Mento-submental angle was significantly lower in males as compared to females being <115° and >115°, respectively. The prevalence of accessory mental foramen was very low in both genders. Conclusions: Sexual dimorphism can be well established from the morphometry of mental foramen of mandibles in the Eastern Indian population.

Public-private-partnership needs under the National Tuberculosis Elimination Program in an Eastern Indian state

Public-private-partnership needs under the National Tuberculosis Elimination Program in an Eastern Indian state

The Longitudinal Antibiotic Susceptibility Pattern Among Gram-negative Bacteria Causing Neonatal Sepsis—From an Eastern Indian Tertiary Care Facility

The Longitudinal Antibiotic Susceptibility Pattern Among Gram-negative Bacteria Causing Neonatal Sepsis—From an Eastern Indian Tertiary Care Facility

Data-driven investigation on the boreal summer MJO predictability

The summer MJO exhibits different characteristics from its winter counterpart, particularly distinguished by propagation in both eastward and northward directions, which is relatively less understood. Here, we explore the primary sources of the summer MJO predictability using Machine Learning (ML) based on the long-term climate model simulation and its transfer learning with the observational data. Our ML-based summer MJO prediction model shows a correlation skill of 0.5 at about 24-day forecast lead time. By utilizing eXplainable Artificial Intelligence (XAI), we discern Precipitable Water (PW) and Surface Temperature (TS) as the most influential sources for the summer MJO predictability. We especially identify the roles of PW and TS in the eastern and northern Indian Ocean (EIO and NIO) regions on the propagation characteristics of the summer MJO through XAI-based sensitivity experiments. These results suggest that ML-based approaches are useful for identifying sources of predictability and their roles in climate phenomena.