The Weddell Sea is susceptible to the ongoing climate change and experiences a reduction in an overall increase in the sea-ice extent (SIE). The nature of sea-ice in the Weddell Sea is largely ...associated with its geographical setup that determines the seasonal and decadal sea-ice variability. The study analysed long-term sea ice-ocean-atmosphere variability and trends (1979-2019) based on satellite and reanalysis measurements. The result shows the expansion of yearly SIE is 2.5 ± 3.5 × 103 km2 yr−1 with a significant increase in the austral summer (12.4 ± 4.6 × 103 km2 yr−1), whereas a decrease in the spring SIE (−4.8 ± 5.0 × 103 km2 yr−1) over the last four decades. Seasonal sea-ice concentration (SIC) variations in the Weddell Sea are associated with latitudinal thermal differences and westerlies intensification, culminating in the weakening or strengthening of the Weddell Gyre. The SIC recorded significant positive trends in the western and eastern parts of the Weddell Sea during the austral summer and autumn, respectively. These changes are consistent with the prevailing wind patterns and Weddell Gyre intensification in the respective seasons. During the austral winter and spring, significant negative SIC trends (north of 65° S) were recorded due to the easterlies intensification and weakening of the Weddell Gyre. While, the significant positive trends observed along the coast are linked with the easterlies intensification and sea-ice advection. Composite analysis reveals that the SIC variability is related to the sea surface temperature (SST) during austral summer and spring, whereas SST and net heat flux both regulate the SIC in the Weddell Sea during the austral winter and autumn. The positive Southern Annular Mode is associated with an increase in sea-ice during austral summer, while sea-ice decreases during the winter in the Weddell Sea. The present study reveals a strong relationship between the sea-ice variability and ocean-atmospheric forcings, but these relationships are not constant over time; therefore, continuous monitoring is required.
The 2023 Antarctic sea ice extent (SIE) maximum on 7 September was the lowest annual maximum in the satellite era (16.98 × 106 km2), with the largest contributions to the anomaly coming from the Ross ...(37.7%, −0.57 × 106 km2) and Weddell (32.9%, −0.49 × 106 km2) Seas. The SIE was low due to anomalously warm (>0.3°C) upper‐ocean temperatures combined with anomalously strong northerly winds impeding the ice advance during the fall and winter. Northerly winds of >12 ms−1 in the Weddell Sea occurred because of negative pressure anomalies over the Antarctic Peninsula, while those in the Ross Sea were associated with extreme blocking episodes off the Ross Ice Shelf. The Ross Sea experienced an unprecedented SIE decrease of −1.08 × 103 km2 d−1 from 1 June till the annual maximum. The passage of quasi‐stationary and explosive polar cyclones contributed to periods of southward ice‐edge shift in both sectors.
Plain Language Summary
Sea ice provides a vital habitat for life in the Southern Ocean, and plays an important role in the ocean circulation, the dynamics of the Earth's climate, the biogeochemical cycle, and the regional ecosystem. Climatologically, Antarctic sea ice expands northwards from the continent each autumn and winter. However, in 2023 an unprecedented slow ice expansion occurred in the Southern Ocean ahead of the annual maximum on 7 September of 16.98 × 106 km2, which was 1.46 × 106 km2 below the long‐term average. In fact, the area covered by ice remained at a record low level every day from 21 April 2023 until 11 November 2023. Our findings suggest that an impact of upper‐ocean warming and changes in winds, combined with heat and moisture fluxes, extreme winds and high ocean waves associated with polar cyclones (storms), contributed to these record low ice conditions. In particular, cyclones caused episodes of exceptional slow ice expansion or even retreat, leading to negative ice anomalies. For instance, the ice‐edge in the Weddell Sea was moved southwards quickly in a few days (up to 256 km southward) with an ice area loss of ∼2.3 × 105 km2, equivalent to the size of United Kingdom.
Key Points
The 2023 Antarctic sea ice extent maximum on 7 September (16.98 × 106 km2) was the lowest annual maximum in the satellite era
Anomalous upper‐ocean warming and strong northerly winds contributed to impeding the ice expansion in the Ross and Weddell Seas
Quasi‐stationary and explosive polar cyclones contributed to periods of southward ice‐edge shift in both sectors
The successful formation of composite parts without defects remains a challenging issue due to the complexity of the forming process. A better understanding of the factors that cause these flaws is ...necessary to optimize the operation. The present work investigates the in-plane shear behavior of out-of-autoclave carbon epoxy thermoset prepregs OOA and its effect on wrinkling using the picture frame test. The deformability of OOA at the real processing conditions helps to understand the applicability of such material for forming processes such as the double-diaphragm forming technique with aims to minimize overall manufacturing time and cost. Tests were performed at varying temperatures and displacement rates in order to determine their contribution to the fabric deformability. Digital image correlation was used to take sequential images at various stages of deformation and capture the onset of wrinkling. It was found that the processing temperature (resin viscosity), displacement rate, and layer counts (layer interactions) are the three most important parameters that influence the wrinkling. Presence of resin between the layers makes them interact with each other and therefore has an impact on the each layer shear angle. These parameters were then analyzed using the Taguchi and analysis of variance techniques to determine which factor has the most significant influence on the wrinkling.
The present study quantifies the magnitude of Arctic sea-ice loss in the boreal summer (July–September), especially in September at different timescales (daily, monthly, annual and decadal). The ...investigation on the accelerated decline in the Arctic sea-ice was performed using different datasets of passive microwave satellite imagery and model reanalysis. Arctic sea-ice declined rapidly in the boreal summer (-10.2 ± 0.8 %decade−1) during 1979–2018, while, the highest decline in sea-ice extent (SIE) (i.e., 82,300 km2 yr−1/-12.8 ± 1.1 %decade−1) is reported in the month of September. Since late 1979, the SIE recorded the sixth-lowest decline during September 2018 (4.71 million km2). Incidentally, the records of twelve lowest extents in the satellite era occurred in the last twelve years. The loss of SIE and sea-ice concentration (SIC) are attributed to the impacts of land-ocean warming and the northward heat advection into the Arctic Ocean. This has resulted in considerable thinning of sea-ice thickness (SIT) and reduction in the multiyear ice (MYI) for summer 2018. Global and Arctic land-ocean temperatures have increased by ~0.78 °C and ~3.1 °C, respectively, over the past 40 years (1979–2018) while substantial warming rates have been identified in the Arctic Ocean (~3.5 °C in the last 40-year) relative to the Arctic land (~2.8 °C in the last 40-year). The prevailing ocean-atmospheric warming in the Arctic, the SIE, SIC and SIT have reduced, resulting in the decline of the sea-ice volume (SIV) at the rate of -3.0 ± 0.2 (1000 km3 decade−1). Further, it observed that the SIV in September 2018 was three times lower than September 1979. The present study demonstrates the linkages of sea-ice dynamics to ice drifting and accelerated melting due to persistent low pressure, high air-ocean temperatures, supplemented by the coupled ocean-atmospheric forcing.
Atmospheric science; Environmental science; Earth sciences; Natural hazards; Oceanography; Arctic sea-ice; Global temperature; Sea-ice thickness; Multiyear ice; Climate change
Objective
To report findings of pilot study using a novel point of care (POC) intraoperative parathyroid hormone (IOPTH) assay for parathyroid hormone (PTH) using whole blood during surgery for ...primary hyperparathyroidism (PHPT).
Methods
Patients undergoing surgery for primary hyperparathyroidism from March to November 2022 where intraoperative PTH assay was performed using the NBCL CONNECT IOPTH and the laboratory PTH assay were included (group 1). The biochemistry results were reviewed to determine concordance between NBCL and lab PTH values and diagnostic test parameters of the NBCL CONNECT assay. ‘In-theatre’ times were then compared with a historical cohort (group 2) where the lab-based IOPTH assay alone was used.
Results
Of the 141 paired samples in group I, correlation between NBCL and the lab assay was high (rho=0.82; p<0.001). PTH levels using the NBCL assay dropped satisfactorily (>50% of the basal or 0 min sample; whichever was lower – i.e. positive test) in 23 patients; giving a positive predictive value of 100%. Of the 9 patients that did not demonstrate a drop, two were true negative (negative predictive value of 22%) leading to cure after excision of another gland. Group 1 (150 mins) had a significantly shorter ‘in-theatre’ time compared to group 2 (167 mins) (p=0.007); despite much higher use of near infra-red autofluorescence (NIRAF) (72% vs 11.6% in group I and 2 respectively).
Conclusion
The NBCL CONNECT POC IOPTH assay gives comparable results to lab based PTH assays and can be performed without need for a centrifuge or qualified technicians. Surgeons, however, need to be aware of the potential for false-negative results.
Antarctic sea ice plays a vital role in global climate via its impact on ocean circulation, biological productivity and CO2 partitioning between the ocean and the atmosphere. However, very little is ...known about its past history, especially in the southwestern Indian sector of the Southern Ocean (SO). We here provide new quantitative records of winter sea-ice concentration (WSIC) and duration (WSID), sea-surface temperatures (SST) and productivity in sediment core SK 200/33 (55°S – 45°E) from the Permanently Open Ocean Zone over the last 156,000 years. The new records, combined with regional records, indicate that the hydrological structures migrated northward by a few degrees of latitude during all glacial periods with the Southern Antarctic Circumpolar Current Front reaching the core site, the Antarctic Polar Front located at ~46°S and the winter sea ice (WSI) probably extending to ~49°S. In contrast, hydrological fronts and WSI edge migrated poleward by a couple of degrees of latitude during the early Holocene and last interglacial. Comparison to SST and WSI records from different sectors of the SO suggests higher amplitude variations in WSI in the Atlantic sector as compared to the Indian and western Pacific sectors over the last glacial-interglacial cycle, which we attribute to the presence of the Weddell Gyre transporting far to the north the sea ice produced in the Weddell Sea. The new records also suggest a drop in productivity in the POOZ during glacial periods, probably related to greater WSI extent and reduced growing season.
•New quantitative records for the Antarctic Indian Sector over the last 156,000 years.•Winter sea-ice limit north of 50°S, APF at ~46°S and SACCF at ~55°S during glacial stages.•Ocean thermodynamics governed sea-ice dynamic.•Winds and ocean currents drove zonal sea-ice amplitude changes.•Contrasted paleoproductivity patterns across the Antarctic Polar Front.
Antarctica, the southernmost continent on Earth, is a harsh and remote place with an extreme climate. Despite its challenges, the continent has become a significant site for scientific research, ...particularly in the fields of earth sciences, glaciology, environmental science, atmospheric sciences, meteorology, palaeoclimatology, and biology. As a signatory to the Antarctic Treaty, India has actively pursued scientific research on the continent since 1981. The Indian Antarctic Program has conducted research, provided logistical support, and monitored environmental activities in Antarctica for over four decades. Science is a currency in Antarctica, and international collaboration is the route to progress. This article explores India's efforts, particularly those of the Ministry of Earth Sciences, Government of India, and the National Centre for Polar and Ocean Research, in fostering international collaboration in Antarctica.
Lignin biosynthesis enzymes form complexes for metabolic channelling during lignification and these enzymes also play an essential role in biotic and abiotic stress response. Cinnamyl alcohol ...dehydrogenase (CAD) is a vital enzyme that catalyses the reduction of aldehydes to alcohols, which is the final step in the lignin biosynthesis pathway. In the present study, we identified 49 CAD enzymes in five Bambusoideae species and analysed their phylogenetic relationships and conserved domains. Expression analysis of Moso bamboo
genes in several developmental tissues and stages revealed that among the
genes,
has the highest expression level and is expressed in many tissues and
,
,
and
were also expressed in most of the tissues studied. Co-expression analysis identified that the
positively correlates with most lignin biosynthesis enzymes, indicating that
might be the key enzyme involved in lignin biosynthesis. Further, more than 35% of the co-expressed genes with
were involved in biotic or abiotic stress responses. Abiotic stress transcriptomic data (SA, ABA, drought, and salt) analysis identified that
,
and
genes were highly upregulated, confirming their involvement in abiotic stress response. Through yeast two-hybrid analysis, we found that
,
and
form homo-dimers. Interestingly, BiFC and pull-down experiments identified that these enzymes form both homo- and hetero- dimers. These data suggest that
genes are involved in abiotic stress response and
might be a key lignin biosynthesis pathway enzyme. Moreover, this is the first report to show that three PheCAD enzymes form complexes and that the formation of PheCAD homo- and hetero- dimers might be tissue specific.
An objective of the study is to get new biogeographic information on the modern polycystine radiolarians from the high-latitude North Atlantic. The quantitative radiolarian dataset was compiled from ...publications and own micropaleontological counts from samples of the bottom surface sediments of the North Atlantic north of 40°N and Nordic Seas. Standard statistical treatment of micropaleontological data by factor analysis reveals five radiolarian assemblages which have their highest load at the specific temperature range in agreement with the oceanographic setting. An occurrence of radiolarian assemblages reflects extension and interaction of the warm North Atlantic and cold Polar/Arctic waters. Radiolarian distribution exhibits good correlation with the climatically averaged summer sea temperature on depth level of 200 m.
Historically, cannabis has been valued for its pain-relieving, anti-inflammatory, and calming properties. Ancient civilizations like the Egyptians, Greeks, and Chinese medicines recognized their ...therapeutic potential. The discovery of the endocannabinoid system, which interacts with cannabis phytoconstituents, has scientifically explained how cannabis affects the human immune system, including the central nervous system (CNS). This review explores the evolving world of cannabis-based treatments, spotlighting its diverse applications. By researching current research and clinical studies, we probe into how cannabinoids like Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) help to manage conditions ranging from chronic pain, persistent inflammation, cancer, inflammatory bowel disease, and neurological disorders to even viral diseases such as Human Immunodeficiency virus (HIV), SARS-CoV-2. and the emerging monkeypox. The long-term recreational use of cannabis can develop into cannabis use disorder (CUD), and therefore, understanding the factors contributing to the development and maintenance of cannabis addiction, including genetic predisposition, neurobiological mechanisms, and environmental influences, will be timely. Shedding light on the adverse impacts of CUD underscores the importance of early intervention, effective treatment approaches, and public health initiatives to address this complex issue in an evolving landscape of cannabis policies and perceptions.
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